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llvm-capstone/clang/lib/AST/ExprConstant.cpp
Daniel Jasper ffdee09350 Revert r301822 (and dependent r301825), which tried to improve the 
handling of constexprs with unknown bounds.

This triggers a corner case of the language where it's not yet clear
whether this should be an error:

  struct A {
    static void *const a[];
    static void *const b[];
  };
  constexpr void *A::a[] = {&b[0]};
  constexpr void *A::b[] = {&a[0]};

When discovering the initializer for A::a, the bounds of A::b aren't known yet.
It is unclear whether warning about errors should be deferred until the end of
the translation unit, possibly resolving errors that can be resolved. In
practice, the compiler can know the bounds of all arrays in this example.

Credits for reproducers and explanation go to Richard Smith. Richard, please
add more info in case my explanation is wrong.

llvm-svn: 301963
2017-05-02 19:21:42 +00:00

10735 lines
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//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Expr constant evaluator.
//
// Constant expression evaluation produces four main results:
//
// * A success/failure flag indicating whether constant folding was successful.
// This is the 'bool' return value used by most of the code in this file. A
// 'false' return value indicates that constant folding has failed, and any
// appropriate diagnostic has already been produced.
//
// * An evaluated result, valid only if constant folding has not failed.
//
// * A flag indicating if evaluation encountered (unevaluated) side-effects.
// These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1),
// where it is possible to determine the evaluated result regardless.
//
// * A set of notes indicating why the evaluation was not a constant expression
// (under the C++11 / C++1y rules only, at the moment), or, if folding failed
// too, why the expression could not be folded.
//
// If we are checking for a potential constant expression, failure to constant
// fold a potential constant sub-expression will be indicated by a 'false'
// return value (the expression could not be folded) and no diagnostic (the
// expression is not necessarily non-constant).
//
//===----------------------------------------------------------------------===//
#include "clang/AST/APValue.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTDiagnostic.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/Expr.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/AST/TypeLoc.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/Support/raw_ostream.h"
#include <cstring>
#include <functional>
using namespace clang;
using llvm::APSInt;
using llvm::APFloat;
static bool IsGlobalLValue(APValue::LValueBase B);
namespace {
struct LValue;
struct CallStackFrame;
struct EvalInfo;
static QualType getType(APValue::LValueBase B) {
if (!B) return QualType();
if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>())
return D->getType();
const Expr *Base = B.get<const Expr*>();
// For a materialized temporary, the type of the temporary we materialized
// may not be the type of the expression.
if (const MaterializeTemporaryExpr *MTE =
dyn_cast<MaterializeTemporaryExpr>(Base)) {
SmallVector<const Expr *, 2> CommaLHSs;
SmallVector<SubobjectAdjustment, 2> Adjustments;
const Expr *Temp = MTE->GetTemporaryExpr();
const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs,
Adjustments);
// Keep any cv-qualifiers from the reference if we generated a temporary
// for it directly. Otherwise use the type after adjustment.
if (!Adjustments.empty())
return Inner->getType();
}
return Base->getType();
}
/// Get an LValue path entry, which is known to not be an array index, as a
/// field or base class.
static
APValue::BaseOrMemberType getAsBaseOrMember(APValue::LValuePathEntry E) {
APValue::BaseOrMemberType Value;
Value.setFromOpaqueValue(E.BaseOrMember);
return Value;
}
/// Get an LValue path entry, which is known to not be an array index, as a
/// field declaration.
static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
return dyn_cast<FieldDecl>(getAsBaseOrMember(E).getPointer());
}
/// Get an LValue path entry, which is known to not be an array index, as a
/// base class declaration.
static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
return dyn_cast<CXXRecordDecl>(getAsBaseOrMember(E).getPointer());
}
/// Determine whether this LValue path entry for a base class names a virtual
/// base class.
static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
return getAsBaseOrMember(E).getInt();
}
/// Given a CallExpr, try to get the alloc_size attribute. May return null.
static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
const FunctionDecl *Callee = CE->getDirectCallee();
return Callee ? Callee->getAttr<AllocSizeAttr>() : nullptr;
}
/// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
/// This will look through a single cast.
///
/// Returns null if we couldn't unwrap a function with alloc_size.
static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
if (!E->getType()->isPointerType())
return nullptr;
E = E->IgnoreParens();
// If we're doing a variable assignment from e.g. malloc(N), there will
// probably be a cast of some kind. Ignore it.
if (const auto *Cast = dyn_cast<CastExpr>(E))
E = Cast->getSubExpr()->IgnoreParens();
if (const auto *CE = dyn_cast<CallExpr>(E))
return getAllocSizeAttr(CE) ? CE : nullptr;
return nullptr;
}
/// Determines whether or not the given Base contains a call to a function
/// with the alloc_size attribute.
static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
const auto *E = Base.dyn_cast<const Expr *>();
return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
}
/// Determines if an LValue with the given LValueBase will have an unsized
/// array in its designator.
/// Find the path length and type of the most-derived subobject in the given
/// path, and find the size of the containing array, if any.
static unsigned
findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
ArrayRef<APValue::LValuePathEntry> Path,
uint64_t &ArraySize, QualType &Type, bool &IsArray) {
// This only accepts LValueBases from APValues, and APValues don't support
// arrays that lack size info.
assert(!isBaseAnAllocSizeCall(Base) &&
"Unsized arrays shouldn't appear here");
unsigned MostDerivedLength = 0;
Type = getType(Base);
for (unsigned I = 0, N = Path.size(); I != N; ++I) {
if (Type->isArrayType()) {
const ConstantArrayType *CAT =
cast<ConstantArrayType>(Ctx.getAsArrayType(Type));
Type = CAT->getElementType();
ArraySize = CAT->getSize().getZExtValue();
MostDerivedLength = I + 1;
IsArray = true;
} else if (Type->isAnyComplexType()) {
const ComplexType *CT = Type->castAs<ComplexType>();
Type = CT->getElementType();
ArraySize = 2;
MostDerivedLength = I + 1;
IsArray = true;
} else if (const FieldDecl *FD = getAsField(Path[I])) {
Type = FD->getType();
ArraySize = 0;
MostDerivedLength = I + 1;
IsArray = false;
} else {
// Path[I] describes a base class.
ArraySize = 0;
IsArray = false;
}
}
return MostDerivedLength;
}
// The order of this enum is important for diagnostics.
enum CheckSubobjectKind {
CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex,
CSK_This, CSK_Real, CSK_Imag
};
/// A path from a glvalue to a subobject of that glvalue.
struct SubobjectDesignator {
/// True if the subobject was named in a manner not supported by C++11. Such
/// lvalues can still be folded, but they are not core constant expressions
/// and we cannot perform lvalue-to-rvalue conversions on them.
unsigned Invalid : 1;
/// Is this a pointer one past the end of an object?
unsigned IsOnePastTheEnd : 1;
/// Indicator of whether the first entry is an unsized array.
unsigned FirstEntryIsAnUnsizedArray : 1;
/// Indicator of whether the most-derived object is an array element.
unsigned MostDerivedIsArrayElement : 1;
/// The length of the path to the most-derived object of which this is a
/// subobject.
unsigned MostDerivedPathLength : 28;
/// The size of the array of which the most-derived object is an element.
/// This will always be 0 if the most-derived object is not an array
/// element. 0 is not an indicator of whether or not the most-derived object
/// is an array, however, because 0-length arrays are allowed.
///
/// If the current array is an unsized array, the value of this is
/// undefined.
uint64_t MostDerivedArraySize;
/// The type of the most derived object referred to by this address.
QualType MostDerivedType;
typedef APValue::LValuePathEntry PathEntry;
/// The entries on the path from the glvalue to the designated subobject.
SmallVector<PathEntry, 8> Entries;
SubobjectDesignator() : Invalid(true) {}
explicit SubobjectDesignator(QualType T)
: Invalid(false), IsOnePastTheEnd(false),
FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
MostDerivedPathLength(0), MostDerivedArraySize(0),
MostDerivedType(T) {}
SubobjectDesignator(ASTContext &Ctx, const APValue &V)
: Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
MostDerivedPathLength(0), MostDerivedArraySize(0) {
assert(V.isLValue() && "Non-LValue used to make an LValue designator?");
if (!Invalid) {
IsOnePastTheEnd = V.isLValueOnePastTheEnd();
ArrayRef<PathEntry> VEntries = V.getLValuePath();
Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
if (V.getLValueBase()) {
bool IsArray = false;
MostDerivedPathLength = findMostDerivedSubobject(
Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
MostDerivedType, IsArray);
MostDerivedIsArrayElement = IsArray;
}
}
}
void setInvalid() {
Invalid = true;
Entries.clear();
}
/// Determine whether the most derived subobject is an array without a
/// known bound.
bool isMostDerivedAnUnsizedArray() const {
assert(!Invalid && "Calling this makes no sense on invalid designators");
return Entries.size() == 1 && FirstEntryIsAnUnsizedArray;
}
/// Determine what the most derived array's size is. Results in an assertion
/// failure if the most derived array lacks a size.
uint64_t getMostDerivedArraySize() const {
assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size");
return MostDerivedArraySize;
}
/// Determine whether this is a one-past-the-end pointer.
bool isOnePastTheEnd() const {
assert(!Invalid);
if (IsOnePastTheEnd)
return true;
if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement &&
Entries[MostDerivedPathLength - 1].ArrayIndex == MostDerivedArraySize)
return true;
return false;
}
/// Check that this refers to a valid subobject.
bool isValidSubobject() const {
if (Invalid)
return false;
return !isOnePastTheEnd();
}
/// Check that this refers to a valid subobject, and if not, produce a
/// relevant diagnostic and set the designator as invalid.
bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);
/// Update this designator to refer to the first element within this array.
void addArrayUnchecked(const ConstantArrayType *CAT) {
PathEntry Entry;
Entry.ArrayIndex = 0;
Entries.push_back(Entry);
// This is a most-derived object.
MostDerivedType = CAT->getElementType();
MostDerivedIsArrayElement = true;
MostDerivedArraySize = CAT->getSize().getZExtValue();
MostDerivedPathLength = Entries.size();
}
/// Update this designator to refer to the first element within the array of
/// elements of type T. This is an array of unknown size.
void addUnsizedArrayUnchecked(QualType ElemTy) {
PathEntry Entry;
Entry.ArrayIndex = 0;
Entries.push_back(Entry);
MostDerivedType = ElemTy;
MostDerivedIsArrayElement = true;
// The value in MostDerivedArraySize is undefined in this case. So, set it
// to an arbitrary value that's likely to loudly break things if it's
// used.
MostDerivedArraySize = std::numeric_limits<uint64_t>::max() / 2;
MostDerivedPathLength = Entries.size();
}
/// Update this designator to refer to the given base or member of this
/// object.
void addDeclUnchecked(const Decl *D, bool Virtual = false) {
PathEntry Entry;
APValue::BaseOrMemberType Value(D, Virtual);
Entry.BaseOrMember = Value.getOpaqueValue();
Entries.push_back(Entry);
// If this isn't a base class, it's a new most-derived object.
if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
MostDerivedType = FD->getType();
MostDerivedIsArrayElement = false;
MostDerivedArraySize = 0;
MostDerivedPathLength = Entries.size();
}
}
/// Update this designator to refer to the given complex component.
void addComplexUnchecked(QualType EltTy, bool Imag) {
PathEntry Entry;
Entry.ArrayIndex = Imag;
Entries.push_back(Entry);
// This is technically a most-derived object, though in practice this
// is unlikely to matter.
MostDerivedType = EltTy;
MostDerivedIsArrayElement = true;
MostDerivedArraySize = 2;
MostDerivedPathLength = Entries.size();
}
void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
const APSInt &N);
/// Add N to the address of this subobject.
void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
if (Invalid || !N) return;
uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
if (isMostDerivedAnUnsizedArray()) {
// Can't verify -- trust that the user is doing the right thing (or if
// not, trust that the caller will catch the bad behavior).
// FIXME: Should we reject if this overflows, at least?
Entries.back().ArrayIndex += TruncatedN;
return;
}
// [expr.add]p4: For the purposes of these operators, a pointer to a
// nonarray object behaves the same as a pointer to the first element of
// an array of length one with the type of the object as its element type.
bool IsArray = MostDerivedPathLength == Entries.size() &&
MostDerivedIsArrayElement;
uint64_t ArrayIndex =
IsArray ? Entries.back().ArrayIndex : (uint64_t)IsOnePastTheEnd;
uint64_t ArraySize =
IsArray ? getMostDerivedArraySize() : (uint64_t)1;
if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) {
// Calculate the actual index in a wide enough type, so we can include
// it in the note.
N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65));
(llvm::APInt&)N += ArrayIndex;
assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index");
diagnosePointerArithmetic(Info, E, N);
setInvalid();
return;
}
ArrayIndex += TruncatedN;
assert(ArrayIndex <= ArraySize &&
"bounds check succeeded for out-of-bounds index");
if (IsArray)
Entries.back().ArrayIndex = ArrayIndex;
else
IsOnePastTheEnd = (ArrayIndex != 0);
}
};
/// A stack frame in the constexpr call stack.
struct CallStackFrame {
EvalInfo &Info;
/// Parent - The caller of this stack frame.
CallStackFrame *Caller;
/// Callee - The function which was called.
const FunctionDecl *Callee;
/// This - The binding for the this pointer in this call, if any.
const LValue *This;
/// Arguments - Parameter bindings for this function call, indexed by
/// parameters' function scope indices.
APValue *Arguments;
// Note that we intentionally use std::map here so that references to
// values are stable.
typedef std::map<const void*, APValue> MapTy;
typedef MapTy::const_iterator temp_iterator;
/// Temporaries - Temporary lvalues materialized within this stack frame.
MapTy Temporaries;
/// CallLoc - The location of the call expression for this call.
SourceLocation CallLoc;
/// Index - The call index of this call.
unsigned Index;
// FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
// on the overall stack usage of deeply-recursing constexpr evaluataions.
// (We should cache this map rather than recomputing it repeatedly.)
// But let's try this and see how it goes; we can look into caching the map
// as a later change.
/// LambdaCaptureFields - Mapping from captured variables/this to
/// corresponding data members in the closure class.
llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields;
FieldDecl *LambdaThisCaptureField;
CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
const FunctionDecl *Callee, const LValue *This,
APValue *Arguments);
~CallStackFrame();
APValue *getTemporary(const void *Key) {
MapTy::iterator I = Temporaries.find(Key);
return I == Temporaries.end() ? nullptr : &I->second;
}
APValue &createTemporary(const void *Key, bool IsLifetimeExtended);
};
/// Temporarily override 'this'.
class ThisOverrideRAII {
public:
ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
: Frame(Frame), OldThis(Frame.This) {
if (Enable)
Frame.This = NewThis;
}
~ThisOverrideRAII() {
Frame.This = OldThis;
}
private:
CallStackFrame &Frame;
const LValue *OldThis;
};
/// A partial diagnostic which we might know in advance that we are not going
/// to emit.
class OptionalDiagnostic {
PartialDiagnostic *Diag;
public:
explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr)
: Diag(Diag) {}
template<typename T>
OptionalDiagnostic &operator<<(const T &v) {
if (Diag)
*Diag << v;
return *this;
}
OptionalDiagnostic &operator<<(const APSInt &I) {
if (Diag) {
SmallVector<char, 32> Buffer;
I.toString(Buffer);
*Diag << StringRef(Buffer.data(), Buffer.size());
}
return *this;
}
OptionalDiagnostic &operator<<(const APFloat &F) {
if (Diag) {
// FIXME: Force the precision of the source value down so we don't
// print digits which are usually useless (we don't really care here if
// we truncate a digit by accident in edge cases). Ideally,
// APFloat::toString would automatically print the shortest
// representation which rounds to the correct value, but it's a bit
// tricky to implement.
unsigned precision =
llvm::APFloat::semanticsPrecision(F.getSemantics());
precision = (precision * 59 + 195) / 196;
SmallVector<char, 32> Buffer;
F.toString(Buffer, precision);
*Diag << StringRef(Buffer.data(), Buffer.size());
}
return *this;
}
};
/// A cleanup, and a flag indicating whether it is lifetime-extended.
class Cleanup {
llvm::PointerIntPair<APValue*, 1, bool> Value;
public:
Cleanup(APValue *Val, bool IsLifetimeExtended)
: Value(Val, IsLifetimeExtended) {}
bool isLifetimeExtended() const { return Value.getInt(); }
void endLifetime() {
*Value.getPointer() = APValue();
}
};
/// EvalInfo - This is a private struct used by the evaluator to capture
/// information about a subexpression as it is folded. It retains information
/// about the AST context, but also maintains information about the folded
/// expression.
///
/// If an expression could be evaluated, it is still possible it is not a C
/// "integer constant expression" or constant expression. If not, this struct
/// captures information about how and why not.
///
/// One bit of information passed *into* the request for constant folding
/// indicates whether the subexpression is "evaluated" or not according to C
/// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
/// evaluate the expression regardless of what the RHS is, but C only allows
/// certain things in certain situations.
struct LLVM_ALIGNAS(/*alignof(uint64_t)*/ 8) EvalInfo {
ASTContext &Ctx;
/// EvalStatus - Contains information about the evaluation.
Expr::EvalStatus &EvalStatus;
/// CurrentCall - The top of the constexpr call stack.
CallStackFrame *CurrentCall;
/// CallStackDepth - The number of calls in the call stack right now.
unsigned CallStackDepth;
/// NextCallIndex - The next call index to assign.
unsigned NextCallIndex;
/// StepsLeft - The remaining number of evaluation steps we're permitted
/// to perform. This is essentially a limit for the number of statements
/// we will evaluate.
unsigned StepsLeft;
/// BottomFrame - The frame in which evaluation started. This must be
/// initialized after CurrentCall and CallStackDepth.
CallStackFrame BottomFrame;
/// A stack of values whose lifetimes end at the end of some surrounding
/// evaluation frame.
llvm::SmallVector<Cleanup, 16> CleanupStack;
/// EvaluatingDecl - This is the declaration whose initializer is being
/// evaluated, if any.
APValue::LValueBase EvaluatingDecl;
/// EvaluatingDeclValue - This is the value being constructed for the
/// declaration whose initializer is being evaluated, if any.
APValue *EvaluatingDeclValue;
/// The current array initialization index, if we're performing array
/// initialization.
uint64_t ArrayInitIndex = -1;
/// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
/// notes attached to it will also be stored, otherwise they will not be.
bool HasActiveDiagnostic;
/// \brief Have we emitted a diagnostic explaining why we couldn't constant
/// fold (not just why it's not strictly a constant expression)?
bool HasFoldFailureDiagnostic;
/// \brief Whether or not we're currently speculatively evaluating.
bool IsSpeculativelyEvaluating;
enum EvaluationMode {
/// Evaluate as a constant expression. Stop if we find that the expression
/// is not a constant expression.
EM_ConstantExpression,
/// Evaluate as a potential constant expression. Keep going if we hit a
/// construct that we can't evaluate yet (because we don't yet know the
/// value of something) but stop if we hit something that could never be
/// a constant expression.
EM_PotentialConstantExpression,
/// Fold the expression to a constant. Stop if we hit a side-effect that
/// we can't model.
EM_ConstantFold,
/// Evaluate the expression looking for integer overflow and similar
/// issues. Don't worry about side-effects, and try to visit all
/// subexpressions.
EM_EvaluateForOverflow,
/// Evaluate in any way we know how. Don't worry about side-effects that
/// can't be modeled.
EM_IgnoreSideEffects,
/// Evaluate as a constant expression. Stop if we find that the expression
/// is not a constant expression. Some expressions can be retried in the
/// optimizer if we don't constant fold them here, but in an unevaluated
/// context we try to fold them immediately since the optimizer never
/// gets a chance to look at it.
EM_ConstantExpressionUnevaluated,
/// Evaluate as a potential constant expression. Keep going if we hit a
/// construct that we can't evaluate yet (because we don't yet know the
/// value of something) but stop if we hit something that could never be
/// a constant expression. Some expressions can be retried in the
/// optimizer if we don't constant fold them here, but in an unevaluated
/// context we try to fold them immediately since the optimizer never
/// gets a chance to look at it.
EM_PotentialConstantExpressionUnevaluated,
/// Evaluate as a constant expression. In certain scenarios, if:
/// - we find a MemberExpr with a base that can't be evaluated, or
/// - we find a variable initialized with a call to a function that has
/// the alloc_size attribute on it
/// then we may consider evaluation to have succeeded.
///
/// In either case, the LValue returned shall have an invalid base; in the
/// former, the base will be the invalid MemberExpr, in the latter, the
/// base will be either the alloc_size CallExpr or a CastExpr wrapping
/// said CallExpr.
EM_OffsetFold,
} EvalMode;
/// Are we checking whether the expression is a potential constant
/// expression?
bool checkingPotentialConstantExpression() const {
return EvalMode == EM_PotentialConstantExpression ||
EvalMode == EM_PotentialConstantExpressionUnevaluated;
}
/// Are we checking an expression for overflow?
// FIXME: We should check for any kind of undefined or suspicious behavior
// in such constructs, not just overflow.
bool checkingForOverflow() { return EvalMode == EM_EvaluateForOverflow; }
EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
: Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
CallStackDepth(0), NextCallIndex(1),
StepsLeft(getLangOpts().ConstexprStepLimit),
BottomFrame(*this, SourceLocation(), nullptr, nullptr, nullptr),
EvaluatingDecl((const ValueDecl *)nullptr),
EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
HasFoldFailureDiagnostic(false), IsSpeculativelyEvaluating(false),
EvalMode(Mode) {}
void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) {
EvaluatingDecl = Base;
EvaluatingDeclValue = &Value;
}
const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); }
bool CheckCallLimit(SourceLocation Loc) {
// Don't perform any constexpr calls (other than the call we're checking)
// when checking a potential constant expression.
if (checkingPotentialConstantExpression() && CallStackDepth > 1)
return false;
if (NextCallIndex == 0) {
// NextCallIndex has wrapped around.
FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
return false;
}
if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
return true;
FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
<< getLangOpts().ConstexprCallDepth;
return false;
}
CallStackFrame *getCallFrame(unsigned CallIndex) {
assert(CallIndex && "no call index in getCallFrame");
// We will eventually hit BottomFrame, which has Index 1, so Frame can't
// be null in this loop.
CallStackFrame *Frame = CurrentCall;
while (Frame->Index > CallIndex)
Frame = Frame->Caller;
return (Frame->Index == CallIndex) ? Frame : nullptr;
}
bool nextStep(const Stmt *S) {
if (!StepsLeft) {
FFDiag(S->getLocStart(), diag::note_constexpr_step_limit_exceeded);
return false;
}
--StepsLeft;
return true;
}
private:
/// Add a diagnostic to the diagnostics list.
PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) {
PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator());
EvalStatus.Diag->push_back(std::make_pair(Loc, PD));
return EvalStatus.Diag->back().second;
}
/// Add notes containing a call stack to the current point of evaluation.
void addCallStack(unsigned Limit);
private:
OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId,
unsigned ExtraNotes, bool IsCCEDiag) {
if (EvalStatus.Diag) {
// If we have a prior diagnostic, it will be noting that the expression
// isn't a constant expression. This diagnostic is more important,
// unless we require this evaluation to produce a constant expression.
//
// FIXME: We might want to show both diagnostics to the user in
// EM_ConstantFold mode.
if (!EvalStatus.Diag->empty()) {
switch (EvalMode) {
case EM_ConstantFold:
case EM_IgnoreSideEffects:
case EM_EvaluateForOverflow:
if (!HasFoldFailureDiagnostic)
break;
// We've already failed to fold something. Keep that diagnostic.
case EM_ConstantExpression:
case EM_PotentialConstantExpression:
case EM_ConstantExpressionUnevaluated:
case EM_PotentialConstantExpressionUnevaluated:
case EM_OffsetFold:
HasActiveDiagnostic = false;
return OptionalDiagnostic();
}
}
unsigned CallStackNotes = CallStackDepth - 1;
unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit();
if (Limit)
CallStackNotes = std::min(CallStackNotes, Limit + 1);
if (checkingPotentialConstantExpression())
CallStackNotes = 0;
HasActiveDiagnostic = true;
HasFoldFailureDiagnostic = !IsCCEDiag;
EvalStatus.Diag->clear();
EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes);
addDiag(Loc, DiagId);
if (!checkingPotentialConstantExpression())
addCallStack(Limit);
return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second);
}
HasActiveDiagnostic = false;
return OptionalDiagnostic();
}
public:
// Diagnose that the evaluation could not be folded (FF => FoldFailure)
OptionalDiagnostic
FFDiag(SourceLocation Loc,
diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr,
unsigned ExtraNotes = 0) {
return Diag(Loc, DiagId, ExtraNotes, false);
}
OptionalDiagnostic FFDiag(const Expr *E, diag::kind DiagId
= diag::note_invalid_subexpr_in_const_expr,
unsigned ExtraNotes = 0) {
if (EvalStatus.Diag)
return Diag(E->getExprLoc(), DiagId, ExtraNotes, /*IsCCEDiag*/false);
HasActiveDiagnostic = false;
return OptionalDiagnostic();
}
/// Diagnose that the evaluation does not produce a C++11 core constant
/// expression.
///
/// FIXME: Stop evaluating if we're in EM_ConstantExpression or
/// EM_PotentialConstantExpression mode and we produce one of these.
OptionalDiagnostic CCEDiag(SourceLocation Loc, diag::kind DiagId
= diag::note_invalid_subexpr_in_const_expr,
unsigned ExtraNotes = 0) {
// Don't override a previous diagnostic. Don't bother collecting
// diagnostics if we're evaluating for overflow.
if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) {
HasActiveDiagnostic = false;
return OptionalDiagnostic();
}
return Diag(Loc, DiagId, ExtraNotes, true);
}
OptionalDiagnostic CCEDiag(const Expr *E, diag::kind DiagId
= diag::note_invalid_subexpr_in_const_expr,
unsigned ExtraNotes = 0) {
return CCEDiag(E->getExprLoc(), DiagId, ExtraNotes);
}
/// Add a note to a prior diagnostic.
OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) {
if (!HasActiveDiagnostic)
return OptionalDiagnostic();
return OptionalDiagnostic(&addDiag(Loc, DiagId));
}
/// Add a stack of notes to a prior diagnostic.
void addNotes(ArrayRef<PartialDiagnosticAt> Diags) {
if (HasActiveDiagnostic) {
EvalStatus.Diag->insert(EvalStatus.Diag->end(),
Diags.begin(), Diags.end());
}
}
/// Should we continue evaluation after encountering a side-effect that we
/// couldn't model?
bool keepEvaluatingAfterSideEffect() {
switch (EvalMode) {
case EM_PotentialConstantExpression:
case EM_PotentialConstantExpressionUnevaluated:
case EM_EvaluateForOverflow:
case EM_IgnoreSideEffects:
return true;
case EM_ConstantExpression:
case EM_ConstantExpressionUnevaluated:
case EM_ConstantFold:
case EM_OffsetFold:
return false;
}
llvm_unreachable("Missed EvalMode case");
}
/// Note that we have had a side-effect, and determine whether we should
/// keep evaluating.
bool noteSideEffect() {
EvalStatus.HasSideEffects = true;
return keepEvaluatingAfterSideEffect();
}
/// Should we continue evaluation after encountering undefined behavior?
bool keepEvaluatingAfterUndefinedBehavior() {
switch (EvalMode) {
case EM_EvaluateForOverflow:
case EM_IgnoreSideEffects:
case EM_ConstantFold:
case EM_OffsetFold:
return true;
case EM_PotentialConstantExpression:
case EM_PotentialConstantExpressionUnevaluated:
case EM_ConstantExpression:
case EM_ConstantExpressionUnevaluated:
return false;
}
llvm_unreachable("Missed EvalMode case");
}
/// Note that we hit something that was technically undefined behavior, but
/// that we can evaluate past it (such as signed overflow or floating-point
/// division by zero.)
bool noteUndefinedBehavior() {
EvalStatus.HasUndefinedBehavior = true;
return keepEvaluatingAfterUndefinedBehavior();
}
/// Should we continue evaluation as much as possible after encountering a
/// construct which can't be reduced to a value?
bool keepEvaluatingAfterFailure() {
if (!StepsLeft)
return false;
switch (EvalMode) {
case EM_PotentialConstantExpression:
case EM_PotentialConstantExpressionUnevaluated:
case EM_EvaluateForOverflow:
return true;
case EM_ConstantExpression:
case EM_ConstantExpressionUnevaluated:
case EM_ConstantFold:
case EM_IgnoreSideEffects:
case EM_OffsetFold:
return false;
}
llvm_unreachable("Missed EvalMode case");
}
/// Notes that we failed to evaluate an expression that other expressions
/// directly depend on, and determine if we should keep evaluating. This
/// should only be called if we actually intend to keep evaluating.
///
/// Call noteSideEffect() instead if we may be able to ignore the value that
/// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
///
/// (Foo(), 1) // use noteSideEffect
/// (Foo() || true) // use noteSideEffect
/// Foo() + 1 // use noteFailure
LLVM_NODISCARD bool noteFailure() {
// Failure when evaluating some expression often means there is some
// subexpression whose evaluation was skipped. Therefore, (because we
// don't track whether we skipped an expression when unwinding after an
// evaluation failure) every evaluation failure that bubbles up from a
// subexpression implies that a side-effect has potentially happened. We
// skip setting the HasSideEffects flag to true until we decide to
// continue evaluating after that point, which happens here.
bool KeepGoing = keepEvaluatingAfterFailure();
EvalStatus.HasSideEffects |= KeepGoing;
return KeepGoing;
}
class ArrayInitLoopIndex {
EvalInfo &Info;
uint64_t OuterIndex;
public:
ArrayInitLoopIndex(EvalInfo &Info)
: Info(Info), OuterIndex(Info.ArrayInitIndex) {
Info.ArrayInitIndex = 0;
}
~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
operator uint64_t&() { return Info.ArrayInitIndex; }
};
};
/// Object used to treat all foldable expressions as constant expressions.
struct FoldConstant {
EvalInfo &Info;
bool Enabled;
bool HadNoPriorDiags;
EvalInfo::EvaluationMode OldMode;
explicit FoldConstant(EvalInfo &Info, bool Enabled)
: Info(Info),
Enabled(Enabled),
HadNoPriorDiags(Info.EvalStatus.Diag &&
Info.EvalStatus.Diag->empty() &&
!Info.EvalStatus.HasSideEffects),
OldMode(Info.EvalMode) {
if (Enabled &&
(Info.EvalMode == EvalInfo::EM_ConstantExpression ||
Info.EvalMode == EvalInfo::EM_ConstantExpressionUnevaluated))
Info.EvalMode = EvalInfo::EM_ConstantFold;
}
void keepDiagnostics() { Enabled = false; }
~FoldConstant() {
if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
!Info.EvalStatus.HasSideEffects)
Info.EvalStatus.Diag->clear();
Info.EvalMode = OldMode;
}
};
/// RAII object used to treat the current evaluation as the correct pointer
/// offset fold for the current EvalMode
struct FoldOffsetRAII {
EvalInfo &Info;
EvalInfo::EvaluationMode OldMode;
explicit FoldOffsetRAII(EvalInfo &Info)
: Info(Info), OldMode(Info.EvalMode) {
if (!Info.checkingPotentialConstantExpression())
Info.EvalMode = EvalInfo::EM_OffsetFold;
}
~FoldOffsetRAII() { Info.EvalMode = OldMode; }
};
/// RAII object used to optionally suppress diagnostics and side-effects from
/// a speculative evaluation.
class SpeculativeEvaluationRAII {
/// Pair of EvalInfo, and a bit that stores whether or not we were
/// speculatively evaluating when we created this RAII.
llvm::PointerIntPair<EvalInfo *, 1, bool> InfoAndOldSpecEval;
Expr::EvalStatus Old;
void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
InfoAndOldSpecEval = Other.InfoAndOldSpecEval;
Old = Other.Old;
Other.InfoAndOldSpecEval.setPointer(nullptr);
}
void maybeRestoreState() {
EvalInfo *Info = InfoAndOldSpecEval.getPointer();
if (!Info)
return;
Info->EvalStatus = Old;
Info->IsSpeculativelyEvaluating = InfoAndOldSpecEval.getInt();
}
public:
SpeculativeEvaluationRAII() = default;
SpeculativeEvaluationRAII(
EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
: InfoAndOldSpecEval(&Info, Info.IsSpeculativelyEvaluating),
Old(Info.EvalStatus) {
Info.EvalStatus.Diag = NewDiag;
Info.IsSpeculativelyEvaluating = true;
}
SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
moveFromAndCancel(std::move(Other));
}
SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
maybeRestoreState();
moveFromAndCancel(std::move(Other));
return *this;
}
~SpeculativeEvaluationRAII() { maybeRestoreState(); }
};
/// RAII object wrapping a full-expression or block scope, and handling
/// the ending of the lifetime of temporaries created within it.
template<bool IsFullExpression>
class ScopeRAII {
EvalInfo &Info;
unsigned OldStackSize;
public:
ScopeRAII(EvalInfo &Info)
: Info(Info), OldStackSize(Info.CleanupStack.size()) {}
~ScopeRAII() {
// Body moved to a static method to encourage the compiler to inline away
// instances of this class.
cleanup(Info, OldStackSize);
}
private:
static void cleanup(EvalInfo &Info, unsigned OldStackSize) {
unsigned NewEnd = OldStackSize;
for (unsigned I = OldStackSize, N = Info.CleanupStack.size();
I != N; ++I) {
if (IsFullExpression && Info.CleanupStack[I].isLifetimeExtended()) {
// Full-expression cleanup of a lifetime-extended temporary: nothing
// to do, just move this cleanup to the right place in the stack.
std::swap(Info.CleanupStack[I], Info.CleanupStack[NewEnd]);
++NewEnd;
} else {
// End the lifetime of the object.
Info.CleanupStack[I].endLifetime();
}
}
Info.CleanupStack.erase(Info.CleanupStack.begin() + NewEnd,
Info.CleanupStack.end());
}
};
typedef ScopeRAII<false> BlockScopeRAII;
typedef ScopeRAII<true> FullExpressionRAII;
}
bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
CheckSubobjectKind CSK) {
if (Invalid)
return false;
if (isOnePastTheEnd()) {
Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
<< CSK;
setInvalid();
return false;
}
return true;
}
void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
const Expr *E,
const APSInt &N) {
// If we're complaining, we must be able to statically determine the size of
// the most derived array.
if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
Info.CCEDiag(E, diag::note_constexpr_array_index)
<< N << /*array*/ 0
<< static_cast<unsigned>(getMostDerivedArraySize());
else
Info.CCEDiag(E, diag::note_constexpr_array_index)
<< N << /*non-array*/ 1;
setInvalid();
}
CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
const FunctionDecl *Callee, const LValue *This,
APValue *Arguments)
: Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
Arguments(Arguments), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
Info.CurrentCall = this;
++Info.CallStackDepth;
}
CallStackFrame::~CallStackFrame() {
assert(Info.CurrentCall == this && "calls retired out of order");
--Info.CallStackDepth;
Info.CurrentCall = Caller;
}
APValue &CallStackFrame::createTemporary(const void *Key,
bool IsLifetimeExtended) {
APValue &Result = Temporaries[Key];
assert(Result.isUninit() && "temporary created multiple times");
Info.CleanupStack.push_back(Cleanup(&Result, IsLifetimeExtended));
return Result;
}
static void describeCall(CallStackFrame *Frame, raw_ostream &Out);
void EvalInfo::addCallStack(unsigned Limit) {
// Determine which calls to skip, if any.
unsigned ActiveCalls = CallStackDepth - 1;
unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart;
if (Limit && Limit < ActiveCalls) {
SkipStart = Limit / 2 + Limit % 2;
SkipEnd = ActiveCalls - Limit / 2;
}
// Walk the call stack and add the diagnostics.
unsigned CallIdx = 0;
for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame;
Frame = Frame->Caller, ++CallIdx) {
// Skip this call?
if (CallIdx >= SkipStart && CallIdx < SkipEnd) {
if (CallIdx == SkipStart) {
// Note that we're skipping calls.
addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed)
<< unsigned(ActiveCalls - Limit);
}
continue;
}
// Use a different note for an inheriting constructor, because from the
// user's perspective it's not really a function at all.
if (auto *CD = dyn_cast_or_null<CXXConstructorDecl>(Frame->Callee)) {
if (CD->isInheritingConstructor()) {
addDiag(Frame->CallLoc, diag::note_constexpr_inherited_ctor_call_here)
<< CD->getParent();
continue;
}
}
SmallVector<char, 128> Buffer;
llvm::raw_svector_ostream Out(Buffer);
describeCall(Frame, Out);
addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str();
}
}
namespace {
struct ComplexValue {
private:
bool IsInt;
public:
APSInt IntReal, IntImag;
APFloat FloatReal, FloatImag;
ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
void makeComplexFloat() { IsInt = false; }
bool isComplexFloat() const { return !IsInt; }
APFloat &getComplexFloatReal() { return FloatReal; }
APFloat &getComplexFloatImag() { return FloatImag; }
void makeComplexInt() { IsInt = true; }
bool isComplexInt() const { return IsInt; }
APSInt &getComplexIntReal() { return IntReal; }
APSInt &getComplexIntImag() { return IntImag; }
void moveInto(APValue &v) const {
if (isComplexFloat())
v = APValue(FloatReal, FloatImag);
else
v = APValue(IntReal, IntImag);
}
void setFrom(const APValue &v) {
assert(v.isComplexFloat() || v.isComplexInt());
if (v.isComplexFloat()) {
makeComplexFloat();
FloatReal = v.getComplexFloatReal();
FloatImag = v.getComplexFloatImag();
} else {
makeComplexInt();
IntReal = v.getComplexIntReal();
IntImag = v.getComplexIntImag();
}
}
};
struct LValue {
APValue::LValueBase Base;
CharUnits Offset;
unsigned InvalidBase : 1;
unsigned CallIndex : 31;
SubobjectDesignator Designator;
bool IsNullPtr;
const APValue::LValueBase getLValueBase() const { return Base; }
CharUnits &getLValueOffset() { return Offset; }
const CharUnits &getLValueOffset() const { return Offset; }
unsigned getLValueCallIndex() const { return CallIndex; }
SubobjectDesignator &getLValueDesignator() { return Designator; }
const SubobjectDesignator &getLValueDesignator() const { return Designator;}
bool isNullPointer() const { return IsNullPtr;}
void moveInto(APValue &V) const {
if (Designator.Invalid)
V = APValue(Base, Offset, APValue::NoLValuePath(), CallIndex,
IsNullPtr);
else {
assert(!InvalidBase && "APValues can't handle invalid LValue bases");
assert(!Designator.FirstEntryIsAnUnsizedArray &&
"Unsized array with a valid base?");
V = APValue(Base, Offset, Designator.Entries,
Designator.IsOnePastTheEnd, CallIndex, IsNullPtr);
}
}
void setFrom(ASTContext &Ctx, const APValue &V) {
assert(V.isLValue() && "Setting LValue from a non-LValue?");
Base = V.getLValueBase();
Offset = V.getLValueOffset();
InvalidBase = false;
CallIndex = V.getLValueCallIndex();
Designator = SubobjectDesignator(Ctx, V);
IsNullPtr = V.isNullPointer();
}
void set(APValue::LValueBase B, unsigned I = 0, bool BInvalid = false,
bool IsNullPtr_ = false, uint64_t Offset_ = 0) {
#ifndef NDEBUG
// We only allow a few types of invalid bases. Enforce that here.
if (BInvalid) {
const auto *E = B.get<const Expr *>();
assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
"Unexpected type of invalid base");
}
#endif
Base = B;
Offset = CharUnits::fromQuantity(Offset_);
InvalidBase = BInvalid;
CallIndex = I;
Designator = SubobjectDesignator(getType(B));
IsNullPtr = IsNullPtr_;
}
void setInvalid(APValue::LValueBase B, unsigned I = 0) {
set(B, I, true);
}
// Check that this LValue is not based on a null pointer. If it is, produce
// a diagnostic and mark the designator as invalid.
bool checkNullPointer(EvalInfo &Info, const Expr *E,
CheckSubobjectKind CSK) {
if (Designator.Invalid)
return false;
if (IsNullPtr) {
Info.CCEDiag(E, diag::note_constexpr_null_subobject)
<< CSK;
Designator.setInvalid();
return false;
}
return true;
}
// Check this LValue refers to an object. If not, set the designator to be
// invalid and emit a diagnostic.
bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
Designator.checkSubobject(Info, E, CSK);
}
void addDecl(EvalInfo &Info, const Expr *E,
const Decl *D, bool Virtual = false) {
if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
Designator.addDeclUnchecked(D, Virtual);
}
void addUnsizedArray(EvalInfo &Info, QualType ElemTy) {
assert(Designator.Entries.empty() && getType(Base)->isPointerType());
assert(isBaseAnAllocSizeCall(Base) &&
"Only alloc_size bases can have unsized arrays");
Designator.FirstEntryIsAnUnsizedArray = true;
Designator.addUnsizedArrayUnchecked(ElemTy);
}
void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
if (checkSubobject(Info, E, CSK_ArrayToPointer))
Designator.addArrayUnchecked(CAT);
}
void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
Designator.addComplexUnchecked(EltTy, Imag);
}
void clearIsNullPointer() {
IsNullPtr = false;
}
void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
const APSInt &Index, CharUnits ElementSize) {
// An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
// but we're not required to diagnose it and it's valid in C++.)
if (!Index)
return;
// Compute the new offset in the appropriate width, wrapping at 64 bits.
// FIXME: When compiling for a 32-bit target, we should use 32-bit
// offsets.
uint64_t Offset64 = Offset.getQuantity();
uint64_t ElemSize64 = ElementSize.getQuantity();
uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
if (checkNullPointer(Info, E, CSK_ArrayIndex))
Designator.adjustIndex(Info, E, Index);
clearIsNullPointer();
}
void adjustOffset(CharUnits N) {
Offset += N;
if (N.getQuantity())
clearIsNullPointer();
}
};
struct MemberPtr {
MemberPtr() {}
explicit MemberPtr(const ValueDecl *Decl) :
DeclAndIsDerivedMember(Decl, false), Path() {}
/// The member or (direct or indirect) field referred to by this member
/// pointer, or 0 if this is a null member pointer.
const ValueDecl *getDecl() const {
return DeclAndIsDerivedMember.getPointer();
}
/// Is this actually a member of some type derived from the relevant class?
bool isDerivedMember() const {
return DeclAndIsDerivedMember.getInt();
}
/// Get the class which the declaration actually lives in.
const CXXRecordDecl *getContainingRecord() const {
return cast<CXXRecordDecl>(
DeclAndIsDerivedMember.getPointer()->getDeclContext());
}
void moveInto(APValue &V) const {
V = APValue(getDecl(), isDerivedMember(), Path);
}
void setFrom(const APValue &V) {
assert(V.isMemberPointer());
DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
Path.clear();
ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
Path.insert(Path.end(), P.begin(), P.end());
}
/// DeclAndIsDerivedMember - The member declaration, and a flag indicating
/// whether the member is a member of some class derived from the class type
/// of the member pointer.
llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
/// Path - The path of base/derived classes from the member declaration's
/// class (exclusive) to the class type of the member pointer (inclusive).
SmallVector<const CXXRecordDecl*, 4> Path;
/// Perform a cast towards the class of the Decl (either up or down the
/// hierarchy).
bool castBack(const CXXRecordDecl *Class) {
assert(!Path.empty());
const CXXRecordDecl *Expected;
if (Path.size() >= 2)
Expected = Path[Path.size() - 2];
else
Expected = getContainingRecord();
if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
// C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
// if B does not contain the original member and is not a base or
// derived class of the class containing the original member, the result
// of the cast is undefined.
// C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
// (D::*). We consider that to be a language defect.
return false;
}
Path.pop_back();
return true;
}
/// Perform a base-to-derived member pointer cast.
bool castToDerived(const CXXRecordDecl *Derived) {
if (!getDecl())
return true;
if (!isDerivedMember()) {
Path.push_back(Derived);
return true;
}
if (!castBack(Derived))
return false;
if (Path.empty())
DeclAndIsDerivedMember.setInt(false);
return true;
}
/// Perform a derived-to-base member pointer cast.
bool castToBase(const CXXRecordDecl *Base) {
if (!getDecl())
return true;
if (Path.empty())
DeclAndIsDerivedMember.setInt(true);
if (isDerivedMember()) {
Path.push_back(Base);
return true;
}
return castBack(Base);
}
};
/// Compare two member pointers, which are assumed to be of the same type.
static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
if (!LHS.getDecl() || !RHS.getDecl())
return !LHS.getDecl() && !RHS.getDecl();
if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
return false;
return LHS.Path == RHS.Path;
}
}
static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
const LValue &This, const Expr *E,
bool AllowNonLiteralTypes = false);
static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
bool InvalidBaseOK = false);
static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
bool InvalidBaseOK = false);
static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
EvalInfo &Info);
static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
EvalInfo &Info);
static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
EvalInfo &Info);
static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
//===----------------------------------------------------------------------===//
// Misc utilities
//===----------------------------------------------------------------------===//
/// Negate an APSInt in place, converting it to a signed form if necessary, and
/// preserving its value (by extending by up to one bit as needed).
static void negateAsSigned(APSInt &Int) {
if (Int.isUnsigned() || Int.isMinSignedValue()) {
Int = Int.extend(Int.getBitWidth() + 1);
Int.setIsSigned(true);
}
Int = -Int;
}
/// Produce a string describing the given constexpr call.
static void describeCall(CallStackFrame *Frame, raw_ostream &Out) {
unsigned ArgIndex = 0;
bool IsMemberCall = isa<CXXMethodDecl>(Frame->Callee) &&
!isa<CXXConstructorDecl>(Frame->Callee) &&
cast<CXXMethodDecl>(Frame->Callee)->isInstance();
if (!IsMemberCall)
Out << *Frame->Callee << '(';
if (Frame->This && IsMemberCall) {
APValue Val;
Frame->This->moveInto(Val);
Val.printPretty(Out, Frame->Info.Ctx,
Frame->This->Designator.MostDerivedType);
// FIXME: Add parens around Val if needed.
Out << "->" << *Frame->Callee << '(';
IsMemberCall = false;
}
for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(),
E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) {
if (ArgIndex > (unsigned)IsMemberCall)
Out << ", ";
const ParmVarDecl *Param = *I;
const APValue &Arg = Frame->Arguments[ArgIndex];
Arg.printPretty(Out, Frame->Info.Ctx, Param->getType());
if (ArgIndex == 0 && IsMemberCall)
Out << "->" << *Frame->Callee << '(';
}
Out << ')';
}
/// Evaluate an expression to see if it had side-effects, and discard its
/// result.
/// \return \c true if the caller should keep evaluating.
static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
APValue Scratch;
if (!Evaluate(Scratch, Info, E))
// We don't need the value, but we might have skipped a side effect here.
return Info.noteSideEffect();
return true;
}
/// Should this call expression be treated as a string literal?
static bool IsStringLiteralCall(const CallExpr *E) {
unsigned Builtin = E->getBuiltinCallee();
return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
Builtin == Builtin::BI__builtin___NSStringMakeConstantString);
}
static bool IsGlobalLValue(APValue::LValueBase B) {
// C++11 [expr.const]p3 An address constant expression is a prvalue core
// constant expression of pointer type that evaluates to...
// ... a null pointer value, or a prvalue core constant expression of type
// std::nullptr_t.
if (!B) return true;
if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
// ... the address of an object with static storage duration,
if (const VarDecl *VD = dyn_cast<VarDecl>(D))
return VD->hasGlobalStorage();
// ... the address of a function,
return isa<FunctionDecl>(D);
}
const Expr *E = B.get<const Expr*>();
switch (E->getStmtClass()) {
default:
return false;
case Expr::CompoundLiteralExprClass: {
const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
return CLE->isFileScope() && CLE->isLValue();
}
case Expr::MaterializeTemporaryExprClass:
// A materialized temporary might have been lifetime-extended to static
// storage duration.
return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
// A string literal has static storage duration.
case Expr::StringLiteralClass:
case Expr::PredefinedExprClass:
case Expr::ObjCStringLiteralClass:
case Expr::ObjCEncodeExprClass:
case Expr::CXXTypeidExprClass:
case Expr::CXXUuidofExprClass:
return true;
case Expr::CallExprClass:
return IsStringLiteralCall(cast<CallExpr>(E));
// For GCC compatibility, &&label has static storage duration.
case Expr::AddrLabelExprClass:
return true;
// A Block literal expression may be used as the initialization value for
// Block variables at global or local static scope.
case Expr::BlockExprClass:
return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
case Expr::ImplicitValueInitExprClass:
// FIXME:
// We can never form an lvalue with an implicit value initialization as its
// base through expression evaluation, so these only appear in one case: the
// implicit variable declaration we invent when checking whether a constexpr
// constructor can produce a constant expression. We must assume that such
// an expression might be a global lvalue.
return true;
}
}
static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
assert(Base && "no location for a null lvalue");
const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
if (VD)
Info.Note(VD->getLocation(), diag::note_declared_at);
else
Info.Note(Base.get<const Expr*>()->getExprLoc(),
diag::note_constexpr_temporary_here);
}
/// Check that this reference or pointer core constant expression is a valid
/// value for an address or reference constant expression. Return true if we
/// can fold this expression, whether or not it's a constant expression.
static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
QualType Type, const LValue &LVal) {
bool IsReferenceType = Type->isReferenceType();
APValue::LValueBase Base = LVal.getLValueBase();
const SubobjectDesignator &Designator = LVal.getLValueDesignator();
// Check that the object is a global. Note that the fake 'this' object we
// manufacture when checking potential constant expressions is conservatively
// assumed to be global here.
if (!IsGlobalLValue(Base)) {
if (Info.getLangOpts().CPlusPlus11) {
const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
<< IsReferenceType << !Designator.Entries.empty()
<< !!VD << VD;
NoteLValueLocation(Info, Base);
} else {
Info.FFDiag(Loc);
}
// Don't allow references to temporaries to escape.
return false;
}
assert((Info.checkingPotentialConstantExpression() ||
LVal.getLValueCallIndex() == 0) &&
"have call index for global lvalue");
if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) {
if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) {
// Check if this is a thread-local variable.
if (Var->getTLSKind())
return false;
// A dllimport variable never acts like a constant.
if (Var->hasAttr<DLLImportAttr>())
return false;
}
if (const auto *FD = dyn_cast<const FunctionDecl>(VD)) {
// __declspec(dllimport) must be handled very carefully:
// We must never initialize an expression with the thunk in C++.
// Doing otherwise would allow the same id-expression to yield
// different addresses for the same function in different translation
// units. However, this means that we must dynamically initialize the
// expression with the contents of the import address table at runtime.
//
// The C language has no notion of ODR; furthermore, it has no notion of
// dynamic initialization. This means that we are permitted to
// perform initialization with the address of the thunk.
if (Info.getLangOpts().CPlusPlus && FD->hasAttr<DLLImportAttr>())
return false;
}
}
// Allow address constant expressions to be past-the-end pointers. This is
// an extension: the standard requires them to point to an object.
if (!IsReferenceType)
return true;
// A reference constant expression must refer to an object.
if (!Base) {
// FIXME: diagnostic
Info.CCEDiag(Loc);
return true;
}
// Does this refer one past the end of some object?
if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
<< !Designator.Entries.empty() << !!VD << VD;
NoteLValueLocation(Info, Base);
}
return true;
}
/// Check that this core constant expression is of literal type, and if not,
/// produce an appropriate diagnostic.
static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
const LValue *This = nullptr) {
if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx))
return true;
// C++1y: A constant initializer for an object o [...] may also invoke
// constexpr constructors for o and its subobjects even if those objects
// are of non-literal class types.
//
// C++11 missed this detail for aggregates, so classes like this:
// struct foo_t { union { int i; volatile int j; } u; };
// are not (obviously) initializable like so:
// __attribute__((__require_constant_initialization__))
// static const foo_t x = {{0}};
// because "i" is a subobject with non-literal initialization (due to the
// volatile member of the union). See:
// http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
// Therefore, we use the C++1y behavior.
if (This && Info.EvaluatingDecl == This->getLValueBase())
return true;
// Prvalue constant expressions must be of literal types.
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(E, diag::note_constexpr_nonliteral)
<< E->getType();
else
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
/// Check that this core constant expression value is a valid value for a
/// constant expression. If not, report an appropriate diagnostic. Does not
/// check that the expression is of literal type.
static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc,
QualType Type, const APValue &Value) {
if (Value.isUninit()) {
Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
<< true << Type;
return false;
}
// We allow _Atomic(T) to be initialized from anything that T can be
// initialized from.
if (const AtomicType *AT = Type->getAs<AtomicType>())
Type = AT->getValueType();
// Core issue 1454: For a literal constant expression of array or class type,
// each subobject of its value shall have been initialized by a constant
// expression.
if (Value.isArray()) {
QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
if (!CheckConstantExpression(Info, DiagLoc, EltTy,
Value.getArrayInitializedElt(I)))
return false;
}
if (!Value.hasArrayFiller())
return true;
return CheckConstantExpression(Info, DiagLoc, EltTy,
Value.getArrayFiller());
}
if (Value.isUnion() && Value.getUnionField()) {
return CheckConstantExpression(Info, DiagLoc,
Value.getUnionField()->getType(),
Value.getUnionValue());
}
if (Value.isStruct()) {
RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
unsigned BaseIndex = 0;
for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(),
End = CD->bases_end(); I != End; ++I, ++BaseIndex) {
if (!CheckConstantExpression(Info, DiagLoc, I->getType(),
Value.getStructBase(BaseIndex)))
return false;
}
}
for (const auto *I : RD->fields()) {
if (!CheckConstantExpression(Info, DiagLoc, I->getType(),
Value.getStructField(I->getFieldIndex())))
return false;
}
}
if (Value.isLValue()) {
LValue LVal;
LVal.setFrom(Info.Ctx, Value);
return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal);
}
// Everything else is fine.
return true;
}
static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
return LVal.Base.dyn_cast<const ValueDecl*>();
}
static bool IsLiteralLValue(const LValue &Value) {
if (Value.CallIndex)
return false;
const Expr *E = Value.Base.dyn_cast<const Expr*>();
return E && !isa<MaterializeTemporaryExpr>(E);
}
static bool IsWeakLValue(const LValue &Value) {
const ValueDecl *Decl = GetLValueBaseDecl(Value);
return Decl && Decl->isWeak();
}
static bool isZeroSized(const LValue &Value) {
const ValueDecl *Decl = GetLValueBaseDecl(Value);
if (Decl && isa<VarDecl>(Decl)) {
QualType Ty = Decl->getType();
if (Ty->isArrayType())
return Ty->isIncompleteType() ||
Decl->getASTContext().getTypeSize(Ty) == 0;
}
return false;
}
static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
// A null base expression indicates a null pointer. These are always
// evaluatable, and they are false unless the offset is zero.
if (!Value.getLValueBase()) {
Result = !Value.getLValueOffset().isZero();
return true;
}
// We have a non-null base. These are generally known to be true, but if it's
// a weak declaration it can be null at runtime.
Result = true;
const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
return !Decl || !Decl->isWeak();
}
static bool HandleConversionToBool(const APValue &Val, bool &Result) {
switch (Val.getKind()) {
case APValue::Uninitialized:
return false;
case APValue::Int:
Result = Val.getInt().getBoolValue();
return true;
case APValue::Float:
Result = !Val.getFloat().isZero();
return true;
case APValue::ComplexInt:
Result = Val.getComplexIntReal().getBoolValue() ||
Val.getComplexIntImag().getBoolValue();
return true;
case APValue::ComplexFloat:
Result = !Val.getComplexFloatReal().isZero() ||
!Val.getComplexFloatImag().isZero();
return true;
case APValue::LValue:
return EvalPointerValueAsBool(Val, Result);
case APValue::MemberPointer:
Result = Val.getMemberPointerDecl();
return true;
case APValue::Vector:
case APValue::Array:
case APValue::Struct:
case APValue::Union:
case APValue::AddrLabelDiff:
return false;
}
llvm_unreachable("unknown APValue kind");
}
static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
EvalInfo &Info) {
assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition");
APValue Val;
if (!Evaluate(Val, Info, E))
return false;
return HandleConversionToBool(Val, Result);
}
template<typename T>
static bool HandleOverflow(EvalInfo &Info, const Expr *E,
const T &SrcValue, QualType DestType) {
Info.CCEDiag(E, diag::note_constexpr_overflow)
<< SrcValue << DestType;
return Info.noteUndefinedBehavior();
}
static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
QualType SrcType, const APFloat &Value,
QualType DestType, APSInt &Result) {
unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
// Determine whether we are converting to unsigned or signed.
bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
Result = APSInt(DestWidth, !DestSigned);
bool ignored;
if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
& APFloat::opInvalidOp)
return HandleOverflow(Info, E, Value, DestType);
return true;
}
static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
QualType SrcType, QualType DestType,
APFloat &Result) {
APFloat Value = Result;
bool ignored;
if (Result.convert(Info.Ctx.getFloatTypeSemantics(DestType),
APFloat::rmNearestTiesToEven, &ignored)
& APFloat::opOverflow)
return HandleOverflow(Info, E, Value, DestType);
return true;
}
static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
QualType DestType, QualType SrcType,
const APSInt &Value) {
unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
APSInt Result = Value;
// Figure out if this is a truncate, extend or noop cast.
// If the input is signed, do a sign extend, noop, or truncate.
Result = Result.extOrTrunc(DestWidth);
Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
return Result;
}
static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
QualType SrcType, const APSInt &Value,
QualType DestType, APFloat &Result) {
Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
if (Result.convertFromAPInt(Value, Value.isSigned(),
APFloat::rmNearestTiesToEven)
& APFloat::opOverflow)
return HandleOverflow(Info, E, Value, DestType);
return true;
}
static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
APValue &Value, const FieldDecl *FD) {
assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield");
if (!Value.isInt()) {
// Trying to store a pointer-cast-to-integer into a bitfield.
// FIXME: In this case, we should provide the diagnostic for casting
// a pointer to an integer.
assert(Value.isLValue() && "integral value neither int nor lvalue?");
Info.FFDiag(E);
return false;
}
APSInt &Int = Value.getInt();
unsigned OldBitWidth = Int.getBitWidth();
unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
if (NewBitWidth < OldBitWidth)
Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
return true;
}
static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
llvm::APInt &Res) {
APValue SVal;
if (!Evaluate(SVal, Info, E))
return false;
if (SVal.isInt()) {
Res = SVal.getInt();
return true;
}
if (SVal.isFloat()) {
Res = SVal.getFloat().bitcastToAPInt();
return true;
}
if (SVal.isVector()) {
QualType VecTy = E->getType();
unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
Res = llvm::APInt::getNullValue(VecSize);
for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
APValue &Elt = SVal.getVectorElt(i);
llvm::APInt EltAsInt;
if (Elt.isInt()) {
EltAsInt = Elt.getInt();
} else if (Elt.isFloat()) {
EltAsInt = Elt.getFloat().bitcastToAPInt();
} else {
// Don't try to handle vectors of anything other than int or float
// (not sure if it's possible to hit this case).
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
unsigned BaseEltSize = EltAsInt.getBitWidth();
if (BigEndian)
Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
else
Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
}
return true;
}
// Give up if the input isn't an int, float, or vector. For example, we
// reject "(v4i16)(intptr_t)&a".
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
/// Perform the given integer operation, which is known to need at most BitWidth
/// bits, and check for overflow in the original type (if that type was not an
/// unsigned type).
template<typename Operation>
static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
const APSInt &LHS, const APSInt &RHS,
unsigned BitWidth, Operation Op,
APSInt &Result) {
if (LHS.isUnsigned()) {
Result = Op(LHS, RHS);
return true;
}
APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
Result = Value.trunc(LHS.getBitWidth());
if (Result.extend(BitWidth) != Value) {
if (Info.checkingForOverflow())
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_integer_constant_overflow)
<< Result.toString(10) << E->getType();
else
return HandleOverflow(Info, E, Value, E->getType());
}
return true;
}
/// Perform the given binary integer operation.
static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
BinaryOperatorKind Opcode, APSInt RHS,
APSInt &Result) {
switch (Opcode) {
default:
Info.FFDiag(E);
return false;
case BO_Mul:
return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
std::multiplies<APSInt>(), Result);
case BO_Add:
return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
std::plus<APSInt>(), Result);
case BO_Sub:
return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
std::minus<APSInt>(), Result);
case BO_And: Result = LHS & RHS; return true;
case BO_Xor: Result = LHS ^ RHS; return true;
case BO_Or: Result = LHS | RHS; return true;
case BO_Div:
case BO_Rem:
if (RHS == 0) {
Info.FFDiag(E, diag::note_expr_divide_by_zero);
return false;
}
Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
// Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
// this operation and gives the two's complement result.
if (RHS.isNegative() && RHS.isAllOnesValue() &&
LHS.isSigned() && LHS.isMinSignedValue())
return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1),
E->getType());
return true;
case BO_Shl: {
if (Info.getLangOpts().OpenCL)
// OpenCL 6.3j: shift values are effectively % word size of LHS.
RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
static_cast<uint64_t>(LHS.getBitWidth() - 1)),
RHS.isUnsigned());
else if (RHS.isSigned() && RHS.isNegative()) {
// During constant-folding, a negative shift is an opposite shift. Such
// a shift is not a constant expression.
Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
RHS = -RHS;
goto shift_right;
}
shift_left:
// C++11 [expr.shift]p1: Shift width must be less than the bit width of
// the shifted type.
unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
if (SA != RHS) {
Info.CCEDiag(E, diag::note_constexpr_large_shift)
<< RHS << E->getType() << LHS.getBitWidth();
} else if (LHS.isSigned()) {
// C++11 [expr.shift]p2: A signed left shift must have a non-negative
// operand, and must not overflow the corresponding unsigned type.
if (LHS.isNegative())
Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
else if (LHS.countLeadingZeros() < SA)
Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
}
Result = LHS << SA;
return true;
}
case BO_Shr: {
if (Info.getLangOpts().OpenCL)
// OpenCL 6.3j: shift values are effectively % word size of LHS.
RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
static_cast<uint64_t>(LHS.getBitWidth() - 1)),
RHS.isUnsigned());
else if (RHS.isSigned() && RHS.isNegative()) {
// During constant-folding, a negative shift is an opposite shift. Such a
// shift is not a constant expression.
Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
RHS = -RHS;
goto shift_left;
}
shift_right:
// C++11 [expr.shift]p1: Shift width must be less than the bit width of the
// shifted type.
unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
if (SA != RHS)
Info.CCEDiag(E, diag::note_constexpr_large_shift)
<< RHS << E->getType() << LHS.getBitWidth();
Result = LHS >> SA;
return true;
}
case BO_LT: Result = LHS < RHS; return true;
case BO_GT: Result = LHS > RHS; return true;
case BO_LE: Result = LHS <= RHS; return true;
case BO_GE: Result = LHS >= RHS; return true;
case BO_EQ: Result = LHS == RHS; return true;
case BO_NE: Result = LHS != RHS; return true;
}
}
/// Perform the given binary floating-point operation, in-place, on LHS.
static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E,
APFloat &LHS, BinaryOperatorKind Opcode,
const APFloat &RHS) {
switch (Opcode) {
default:
Info.FFDiag(E);
return false;
case BO_Mul:
LHS.multiply(RHS, APFloat::rmNearestTiesToEven);
break;
case BO_Add:
LHS.add(RHS, APFloat::rmNearestTiesToEven);
break;
case BO_Sub:
LHS.subtract(RHS, APFloat::rmNearestTiesToEven);
break;
case BO_Div:
LHS.divide(RHS, APFloat::rmNearestTiesToEven);
break;
}
if (LHS.isInfinity() || LHS.isNaN()) {
Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
return Info.noteUndefinedBehavior();
}
return true;
}
/// Cast an lvalue referring to a base subobject to a derived class, by
/// truncating the lvalue's path to the given length.
static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
const RecordDecl *TruncatedType,
unsigned TruncatedElements) {
SubobjectDesignator &D = Result.Designator;
// Check we actually point to a derived class object.
if (TruncatedElements == D.Entries.size())
return true;
assert(TruncatedElements >= D.MostDerivedPathLength &&
"not casting to a derived class");
if (!Result.checkSubobject(Info, E, CSK_Derived))
return false;
// Truncate the path to the subobject, and remove any derived-to-base offsets.
const RecordDecl *RD = TruncatedType;
for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
if (isVirtualBaseClass(D.Entries[I]))
Result.Offset -= Layout.getVBaseClassOffset(Base);
else
Result.Offset -= Layout.getBaseClassOffset(Base);
RD = Base;
}
D.Entries.resize(TruncatedElements);
return true;
}
static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
const CXXRecordDecl *Derived,
const CXXRecordDecl *Base,
const ASTRecordLayout *RL = nullptr) {
if (!RL) {
if (Derived->isInvalidDecl()) return false;
RL = &Info.Ctx.getASTRecordLayout(Derived);
}
Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
Obj.addDecl(Info, E, Base, /*Virtual*/ false);
return true;
}
static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
const CXXRecordDecl *DerivedDecl,
const CXXBaseSpecifier *Base) {
const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
if (!Base->isVirtual())
return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
SubobjectDesignator &D = Obj.Designator;
if (D.Invalid)
return false;
// Extract most-derived object and corresponding type.
DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
return false;
// Find the virtual base class.
if (DerivedDecl->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
return true;
}
static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
QualType Type, LValue &Result) {
for (CastExpr::path_const_iterator PathI = E->path_begin(),
PathE = E->path_end();
PathI != PathE; ++PathI) {
if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
*PathI))
return false;
Type = (*PathI)->getType();
}
return true;
}
/// Update LVal to refer to the given field, which must be a member of the type
/// currently described by LVal.
static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
const FieldDecl *FD,
const ASTRecordLayout *RL = nullptr) {
if (!RL) {
if (FD->getParent()->isInvalidDecl()) return false;
RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
}
unsigned I = FD->getFieldIndex();
LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
LVal.addDecl(Info, E, FD);
return true;
}
/// Update LVal to refer to the given indirect field.
static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
LValue &LVal,
const IndirectFieldDecl *IFD) {
for (const auto *C : IFD->chain())
if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
return false;
return true;
}
/// Get the size of the given type in char units.
static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
QualType Type, CharUnits &Size) {
// sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
// extension.
if (Type->isVoidType() || Type->isFunctionType()) {
Size = CharUnits::One();
return true;
}
if (Type->isDependentType()) {
Info.FFDiag(Loc);
return false;
}
if (!Type->isConstantSizeType()) {
// sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
// FIXME: Better diagnostic.
Info.FFDiag(Loc);
return false;
}
Size = Info.Ctx.getTypeSizeInChars(Type);
return true;
}
/// Update a pointer value to model pointer arithmetic.
/// \param Info - Information about the ongoing evaluation.
/// \param E - The expression being evaluated, for diagnostic purposes.
/// \param LVal - The pointer value to be updated.
/// \param EltTy - The pointee type represented by LVal.
/// \param Adjustment - The adjustment, in objects of type EltTy, to add.
static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
LValue &LVal, QualType EltTy,
APSInt Adjustment) {
CharUnits SizeOfPointee;
if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
return false;
LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
return true;
}
static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
LValue &LVal, QualType EltTy,
int64_t Adjustment) {
return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
APSInt::get(Adjustment));
}
/// Update an lvalue to refer to a component of a complex number.
/// \param Info - Information about the ongoing evaluation.
/// \param LVal - The lvalue to be updated.
/// \param EltTy - The complex number's component type.
/// \param Imag - False for the real component, true for the imaginary.
static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
LValue &LVal, QualType EltTy,
bool Imag) {
if (Imag) {
CharUnits SizeOfComponent;
if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
return false;
LVal.Offset += SizeOfComponent;
}
LVal.addComplex(Info, E, EltTy, Imag);
return true;
}
static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv,
QualType Type, const LValue &LVal,
APValue &RVal);
/// Try to evaluate the initializer for a variable declaration.
///
/// \param Info Information about the ongoing evaluation.
/// \param E An expression to be used when printing diagnostics.
/// \param VD The variable whose initializer should be obtained.
/// \param Frame The frame in which the variable was created. Must be null
/// if this variable is not local to the evaluation.
/// \param Result Filled in with a pointer to the value of the variable.
static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
const VarDecl *VD, CallStackFrame *Frame,
APValue *&Result) {
// If this is a parameter to an active constexpr function call, perform
// argument substitution.
if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) {
// Assume arguments of a potential constant expression are unknown
// constant expressions.
if (Info.checkingPotentialConstantExpression())
return false;
if (!Frame || !Frame->Arguments) {
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
Result = &Frame->Arguments[PVD->getFunctionScopeIndex()];
return true;
}
// If this is a local variable, dig out its value.
if (Frame) {
Result = Frame->getTemporary(VD);
if (!Result) {
// Assume variables referenced within a lambda's call operator that were
// not declared within the call operator are captures and during checking
// of a potential constant expression, assume they are unknown constant
// expressions.
assert(isLambdaCallOperator(Frame->Callee) &&
(VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&
"missing value for local variable");
if (Info.checkingPotentialConstantExpression())
return false;
// FIXME: implement capture evaluation during constant expr evaluation.
Info.FFDiag(E->getLocStart(),
diag::note_unimplemented_constexpr_lambda_feature_ast)
<< "captures not currently allowed";
return false;
}
return true;
}
// Dig out the initializer, and use the declaration which it's attached to.
const Expr *Init = VD->getAnyInitializer(VD);
if (!Init || Init->isValueDependent()) {
// If we're checking a potential constant expression, the variable could be
// initialized later.
if (!Info.checkingPotentialConstantExpression())
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
// If we're currently evaluating the initializer of this declaration, use that
// in-flight value.
if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) {
Result = Info.EvaluatingDeclValue;
return true;
}
// Never evaluate the initializer of a weak variable. We can't be sure that
// this is the definition which will be used.
if (VD->isWeak()) {
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
// Check that we can fold the initializer. In C++, we will have already done
// this in the cases where it matters for conformance.
SmallVector<PartialDiagnosticAt, 8> Notes;
if (!VD->evaluateValue(Notes)) {
Info.FFDiag(E, diag::note_constexpr_var_init_non_constant,
Notes.size() + 1) << VD;
Info.Note(VD->getLocation(), diag::note_declared_at);
Info.addNotes(Notes);
return false;
} else if (!VD->checkInitIsICE()) {
Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant,
Notes.size() + 1) << VD;
Info.Note(VD->getLocation(), diag::note_declared_at);
Info.addNotes(Notes);
}
Result = VD->getEvaluatedValue();
return true;
}
static bool IsConstNonVolatile(QualType T) {
Qualifiers Quals = T.getQualifiers();
return Quals.hasConst() && !Quals.hasVolatile();
}
/// Get the base index of the given base class within an APValue representing
/// the given derived class.
static unsigned getBaseIndex(const CXXRecordDecl *Derived,
const CXXRecordDecl *Base) {
Base = Base->getCanonicalDecl();
unsigned Index = 0;
for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
E = Derived->bases_end(); I != E; ++I, ++Index) {
if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
return Index;
}
llvm_unreachable("base class missing from derived class's bases list");
}
/// Extract the value of a character from a string literal.
static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
uint64_t Index) {
// FIXME: Support MakeStringConstant
if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
std::string Str;
Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
assert(Index <= Str.size() && "Index too large");
return APSInt::getUnsigned(Str.c_str()[Index]);
}
if (auto PE = dyn_cast<PredefinedExpr>(Lit))
Lit = PE->getFunctionName();
const StringLiteral *S = cast<StringLiteral>(Lit);
const ConstantArrayType *CAT =
Info.Ctx.getAsConstantArrayType(S->getType());
assert(CAT && "string literal isn't an array");
QualType CharType = CAT->getElementType();
assert(CharType->isIntegerType() && "unexpected character type");
APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
CharType->isUnsignedIntegerType());
if (Index < S->getLength())
Value = S->getCodeUnit(Index);
return Value;
}
// Expand a string literal into an array of characters.
static void expandStringLiteral(EvalInfo &Info, const Expr *Lit,
APValue &Result) {
const StringLiteral *S = cast<StringLiteral>(Lit);
const ConstantArrayType *CAT =
Info.Ctx.getAsConstantArrayType(S->getType());
assert(CAT && "string literal isn't an array");
QualType CharType = CAT->getElementType();
assert(CharType->isIntegerType() && "unexpected character type");
unsigned Elts = CAT->getSize().getZExtValue();
Result = APValue(APValue::UninitArray(),
std::min(S->getLength(), Elts), Elts);
APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
CharType->isUnsignedIntegerType());
if (Result.hasArrayFiller())
Result.getArrayFiller() = APValue(Value);
for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
Value = S->getCodeUnit(I);
Result.getArrayInitializedElt(I) = APValue(Value);
}
}
// Expand an array so that it has more than Index filled elements.
static void expandArray(APValue &Array, unsigned Index) {
unsigned Size = Array.getArraySize();
assert(Index < Size);
// Always at least double the number of elements for which we store a value.
unsigned OldElts = Array.getArrayInitializedElts();
unsigned NewElts = std::max(Index+1, OldElts * 2);
NewElts = std::min(Size, std::max(NewElts, 8u));
// Copy the data across.
APValue NewValue(APValue::UninitArray(), NewElts, Size);
for (unsigned I = 0; I != OldElts; ++I)
NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
for (unsigned I = OldElts; I != NewElts; ++I)
NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
if (NewValue.hasArrayFiller())
NewValue.getArrayFiller() = Array.getArrayFiller();
Array.swap(NewValue);
}
/// Determine whether a type would actually be read by an lvalue-to-rvalue
/// conversion. If it's of class type, we may assume that the copy operation
/// is trivial. Note that this is never true for a union type with fields
/// (because the copy always "reads" the active member) and always true for
/// a non-class type.
static bool isReadByLvalueToRvalueConversion(QualType T) {
CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
if (!RD || (RD->isUnion() && !RD->field_empty()))
return true;
if (RD->isEmpty())
return false;
for (auto *Field : RD->fields())
if (isReadByLvalueToRvalueConversion(Field->getType()))
return true;
for (auto &BaseSpec : RD->bases())
if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
return true;
return false;
}
/// Diagnose an attempt to read from any unreadable field within the specified
/// type, which might be a class type.
static bool diagnoseUnreadableFields(EvalInfo &Info, const Expr *E,
QualType T) {
CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
if (!RD)
return false;
if (!RD->hasMutableFields())
return false;
for (auto *Field : RD->fields()) {
// If we're actually going to read this field in some way, then it can't
// be mutable. If we're in a union, then assigning to a mutable field
// (even an empty one) can change the active member, so that's not OK.
// FIXME: Add core issue number for the union case.
if (Field->isMutable() &&
(RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) << Field;
Info.Note(Field->getLocation(), diag::note_declared_at);
return true;
}
if (diagnoseUnreadableFields(Info, E, Field->getType()))
return true;
}
for (auto &BaseSpec : RD->bases())
if (diagnoseUnreadableFields(Info, E, BaseSpec.getType()))
return true;
// All mutable fields were empty, and thus not actually read.
return false;
}
/// Kinds of access we can perform on an object, for diagnostics.
enum AccessKinds {
AK_Read,
AK_Assign,
AK_Increment,
AK_Decrement
};
namespace {
/// A handle to a complete object (an object that is not a subobject of
/// another object).
struct CompleteObject {
/// The value of the complete object.
APValue *Value;
/// The type of the complete object.
QualType Type;
CompleteObject() : Value(nullptr) {}
CompleteObject(APValue *Value, QualType Type)
: Value(Value), Type(Type) {
assert(Value && "missing value for complete object");
}
explicit operator bool() const { return Value; }
};
} // end anonymous namespace
/// Find the designated sub-object of an rvalue.
template<typename SubobjectHandler>
typename SubobjectHandler::result_type
findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
const SubobjectDesignator &Sub, SubobjectHandler &handler) {
if (Sub.Invalid)
// A diagnostic will have already been produced.
return handler.failed();
if (Sub.isOnePastTheEnd()) {
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(E, diag::note_constexpr_access_past_end)
<< handler.AccessKind;
else
Info.FFDiag(E);
return handler.failed();
}
APValue *O = Obj.Value;
QualType ObjType = Obj.Type;
const FieldDecl *LastField = nullptr;
// Walk the designator's path to find the subobject.
for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
if (O->isUninit()) {
if (!Info.checkingPotentialConstantExpression())
Info.FFDiag(E, diag::note_constexpr_access_uninit) << handler.AccessKind;
return handler.failed();
}
if (I == N) {
// If we are reading an object of class type, there may still be more
// things we need to check: if there are any mutable subobjects, we
// cannot perform this read. (This only happens when performing a trivial
// copy or assignment.)
if (ObjType->isRecordType() && handler.AccessKind == AK_Read &&
diagnoseUnreadableFields(Info, E, ObjType))
return handler.failed();
if (!handler.found(*O, ObjType))
return false;
// If we modified a bit-field, truncate it to the right width.
if (handler.AccessKind != AK_Read &&
LastField && LastField->isBitField() &&
!truncateBitfieldValue(Info, E, *O, LastField))
return false;
return true;
}
LastField = nullptr;
if (ObjType->isArrayType()) {
// Next subobject is an array element.
const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
assert(CAT && "vla in literal type?");
uint64_t Index = Sub.Entries[I].ArrayIndex;
if (CAT->getSize().ule(Index)) {
// Note, it should not be possible to form a pointer with a valid
// designator which points more than one past the end of the array.
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(E, diag::note_constexpr_access_past_end)
<< handler.AccessKind;
else
Info.FFDiag(E);
return handler.failed();
}
ObjType = CAT->getElementType();
// An array object is represented as either an Array APValue or as an
// LValue which refers to a string literal.
if (O->isLValue()) {
assert(I == N - 1 && "extracting subobject of character?");
assert(!O->hasLValuePath() || O->getLValuePath().empty());
if (handler.AccessKind != AK_Read)
expandStringLiteral(Info, O->getLValueBase().get<const Expr *>(),
*O);
else
return handler.foundString(*O, ObjType, Index);
}
if (O->getArrayInitializedElts() > Index)
O = &O->getArrayInitializedElt(Index);
else if (handler.AccessKind != AK_Read) {
expandArray(*O, Index);
O = &O->getArrayInitializedElt(Index);
} else
O = &O->getArrayFiller();
} else if (ObjType->isAnyComplexType()) {
// Next subobject is a complex number.
uint64_t Index = Sub.Entries[I].ArrayIndex;
if (Index > 1) {
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(E, diag::note_constexpr_access_past_end)
<< handler.AccessKind;
else
Info.FFDiag(E);
return handler.failed();
}
bool WasConstQualified = ObjType.isConstQualified();
ObjType = ObjType->castAs<ComplexType>()->getElementType();
if (WasConstQualified)
ObjType.addConst();
assert(I == N - 1 && "extracting subobject of scalar?");
if (O->isComplexInt()) {
return handler.found(Index ? O->getComplexIntImag()
: O->getComplexIntReal(), ObjType);
} else {
assert(O->isComplexFloat());
return handler.found(Index ? O->getComplexFloatImag()
: O->getComplexFloatReal(), ObjType);
}
} else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
if (Field->isMutable() && handler.AccessKind == AK_Read) {
Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1)
<< Field;
Info.Note(Field->getLocation(), diag::note_declared_at);
return handler.failed();
}
// Next subobject is a class, struct or union field.
RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
if (RD->isUnion()) {
const FieldDecl *UnionField = O->getUnionField();
if (!UnionField ||
UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
<< handler.AccessKind << Field << !UnionField << UnionField;
return handler.failed();
}
O = &O->getUnionValue();
} else
O = &O->getStructField(Field->getFieldIndex());
bool WasConstQualified = ObjType.isConstQualified();
ObjType = Field->getType();
if (WasConstQualified && !Field->isMutable())
ObjType.addConst();
if (ObjType.isVolatileQualified()) {
if (Info.getLangOpts().CPlusPlus) {
// FIXME: Include a description of the path to the volatile subobject.
Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
<< handler.AccessKind << 2 << Field;
Info.Note(Field->getLocation(), diag::note_declared_at);
} else {
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
}
return handler.failed();
}
LastField = Field;
} else {
// Next subobject is a base class.
const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
O = &O->getStructBase(getBaseIndex(Derived, Base));
bool WasConstQualified = ObjType.isConstQualified();
ObjType = Info.Ctx.getRecordType(Base);
if (WasConstQualified)
ObjType.addConst();
}
}
}
namespace {
struct ExtractSubobjectHandler {
EvalInfo &Info;
APValue &Result;
static const AccessKinds AccessKind = AK_Read;
typedef bool result_type;
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) {
Result = Subobj;
return true;
}
bool found(APSInt &Value, QualType SubobjType) {
Result = APValue(Value);
return true;
}
bool found(APFloat &Value, QualType SubobjType) {
Result = APValue(Value);
return true;
}
bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
Result = APValue(extractStringLiteralCharacter(
Info, Subobj.getLValueBase().get<const Expr *>(), Character));
return true;
}
};
} // end anonymous namespace
const AccessKinds ExtractSubobjectHandler::AccessKind;
/// Extract the designated sub-object of an rvalue.
static bool extractSubobject(EvalInfo &Info, const Expr *E,
const CompleteObject &Obj,
const SubobjectDesignator &Sub,
APValue &Result) {
ExtractSubobjectHandler Handler = { Info, Result };
return findSubobject(Info, E, Obj, Sub, Handler);
}
namespace {
struct ModifySubobjectHandler {
EvalInfo &Info;
APValue &NewVal;
const Expr *E;
typedef bool result_type;
static const AccessKinds AccessKind = AK_Assign;
bool checkConst(QualType QT) {
// Assigning to a const object has undefined behavior.
if (QT.isConstQualified()) {
Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
return false;
}
return true;
}
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
// We've been given ownership of NewVal, so just swap it in.
Subobj.swap(NewVal);
return true;
}
bool found(APSInt &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
if (!NewVal.isInt()) {
// Maybe trying to write a cast pointer value into a complex?
Info.FFDiag(E);
return false;
}
Value = NewVal.getInt();
return true;
}
bool found(APFloat &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
Value = NewVal.getFloat();
return true;
}
bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
llvm_unreachable("shouldn't encounter string elements with ExpandArrays");
}
};
} // end anonymous namespace
const AccessKinds ModifySubobjectHandler::AccessKind;
/// Update the designated sub-object of an rvalue to the given value.
static bool modifySubobject(EvalInfo &Info, const Expr *E,
const CompleteObject &Obj,
const SubobjectDesignator &Sub,
APValue &NewVal) {
ModifySubobjectHandler Handler = { Info, NewVal, E };
return findSubobject(Info, E, Obj, Sub, Handler);
}
/// Find the position where two subobject designators diverge, or equivalently
/// the length of the common initial subsequence.
static unsigned FindDesignatorMismatch(QualType ObjType,
const SubobjectDesignator &A,
const SubobjectDesignator &B,
bool &WasArrayIndex) {
unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
for (/**/; I != N; ++I) {
if (!ObjType.isNull() &&
(ObjType->isArrayType() || ObjType->isAnyComplexType())) {
// Next subobject is an array element.
if (A.Entries[I].ArrayIndex != B.Entries[I].ArrayIndex) {
WasArrayIndex = true;
return I;
}
if (ObjType->isAnyComplexType())
ObjType = ObjType->castAs<ComplexType>()->getElementType();
else
ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
} else {
if (A.Entries[I].BaseOrMember != B.Entries[I].BaseOrMember) {
WasArrayIndex = false;
return I;
}
if (const FieldDecl *FD = getAsField(A.Entries[I]))
// Next subobject is a field.
ObjType = FD->getType();
else
// Next subobject is a base class.
ObjType = QualType();
}
}
WasArrayIndex = false;
return I;
}
/// Determine whether the given subobject designators refer to elements of the
/// same array object.
static bool AreElementsOfSameArray(QualType ObjType,
const SubobjectDesignator &A,
const SubobjectDesignator &B) {
if (A.Entries.size() != B.Entries.size())
return false;
bool IsArray = A.MostDerivedIsArrayElement;
if (IsArray && A.MostDerivedPathLength != A.Entries.size())
// A is a subobject of the array element.
return false;
// If A (and B) designates an array element, the last entry will be the array
// index. That doesn't have to match. Otherwise, we're in the 'implicit array
// of length 1' case, and the entire path must match.
bool WasArrayIndex;
unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
return CommonLength >= A.Entries.size() - IsArray;
}
/// Find the complete object to which an LValue refers.
static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
AccessKinds AK, const LValue &LVal,
QualType LValType) {
if (!LVal.Base) {
Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
return CompleteObject();
}
CallStackFrame *Frame = nullptr;
if (LVal.CallIndex) {
Frame = Info.getCallFrame(LVal.CallIndex);
if (!Frame) {
Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
<< AK << LVal.Base.is<const ValueDecl*>();
NoteLValueLocation(Info, LVal.Base);
return CompleteObject();
}
}
// C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
// is not a constant expression (even if the object is non-volatile). We also
// apply this rule to C++98, in order to conform to the expected 'volatile'
// semantics.
if (LValType.isVolatileQualified()) {
if (Info.getLangOpts().CPlusPlus)
Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
<< AK << LValType;
else
Info.FFDiag(E);
return CompleteObject();
}
// Compute value storage location and type of base object.
APValue *BaseVal = nullptr;
QualType BaseType = getType(LVal.Base);
if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) {
// In C++98, const, non-volatile integers initialized with ICEs are ICEs.
// In C++11, constexpr, non-volatile variables initialized with constant
// expressions are constant expressions too. Inside constexpr functions,
// parameters are constant expressions even if they're non-const.
// In C++1y, objects local to a constant expression (those with a Frame) are
// both readable and writable inside constant expressions.
// In C, such things can also be folded, although they are not ICEs.
const VarDecl *VD = dyn_cast<VarDecl>(D);
if (VD) {
if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
VD = VDef;
}
if (!VD || VD->isInvalidDecl()) {
Info.FFDiag(E);
return CompleteObject();
}
// Accesses of volatile-qualified objects are not allowed.
if (BaseType.isVolatileQualified()) {
if (Info.getLangOpts().CPlusPlus) {
Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
<< AK << 1 << VD;
Info.Note(VD->getLocation(), diag::note_declared_at);
} else {
Info.FFDiag(E);
}
return CompleteObject();
}
// Unless we're looking at a local variable or argument in a constexpr call,
// the variable we're reading must be const.
if (!Frame) {
if (Info.getLangOpts().CPlusPlus14 &&
VD == Info.EvaluatingDecl.dyn_cast<const ValueDecl *>()) {
// OK, we can read and modify an object if we're in the process of
// evaluating its initializer, because its lifetime began in this
// evaluation.
} else if (AK != AK_Read) {
// All the remaining cases only permit reading.
Info.FFDiag(E, diag::note_constexpr_modify_global);
return CompleteObject();
} else if (VD->isConstexpr()) {
// OK, we can read this variable.
} else if (BaseType->isIntegralOrEnumerationType()) {
// In OpenCL if a variable is in constant address space it is a const value.
if (!(BaseType.isConstQualified() ||
(Info.getLangOpts().OpenCL &&
BaseType.getAddressSpace() == LangAS::opencl_constant))) {
if (Info.getLangOpts().CPlusPlus) {
Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
Info.Note(VD->getLocation(), diag::note_declared_at);
} else {
Info.FFDiag(E);
}
return CompleteObject();
}
} else if (BaseType->isFloatingType() && BaseType.isConstQualified()) {
// We support folding of const floating-point types, in order to make
// static const data members of such types (supported as an extension)
// more useful.
if (Info.getLangOpts().CPlusPlus11) {
Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
Info.Note(VD->getLocation(), diag::note_declared_at);
} else {
Info.CCEDiag(E);
}
} else if (BaseType.isConstQualified() && VD->hasDefinition(Info.Ctx)) {
Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr) << VD;
// Keep evaluating to see what we can do.
} else {
// FIXME: Allow folding of values of any literal type in all languages.
if (Info.checkingPotentialConstantExpression() &&
VD->getType().isConstQualified() && !VD->hasDefinition(Info.Ctx)) {
// The definition of this variable could be constexpr. We can't
// access it right now, but may be able to in future.
} else if (Info.getLangOpts().CPlusPlus11) {
Info.FFDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD;
Info.Note(VD->getLocation(), diag::note_declared_at);
} else {
Info.FFDiag(E);
}
return CompleteObject();
}
}
if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal))
return CompleteObject();
} else {
const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
if (!Frame) {
if (const MaterializeTemporaryExpr *MTE =
dyn_cast<MaterializeTemporaryExpr>(Base)) {
assert(MTE->getStorageDuration() == SD_Static &&
"should have a frame for a non-global materialized temporary");
// Per C++1y [expr.const]p2:
// an lvalue-to-rvalue conversion [is not allowed unless it applies to]
// - a [...] glvalue of integral or enumeration type that refers to
// a non-volatile const object [...]
// [...]
// - a [...] glvalue of literal type that refers to a non-volatile
// object whose lifetime began within the evaluation of e.
//
// C++11 misses the 'began within the evaluation of e' check and
// instead allows all temporaries, including things like:
// int &&r = 1;
// int x = ++r;
// constexpr int k = r;
// Therefore we use the C++1y rules in C++11 too.
const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>();
const ValueDecl *ED = MTE->getExtendingDecl();
if (!(BaseType.isConstQualified() &&
BaseType->isIntegralOrEnumerationType()) &&
!(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) {
Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
return CompleteObject();
}
BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false);
assert(BaseVal && "got reference to unevaluated temporary");
} else {
Info.FFDiag(E);
return CompleteObject();
}
} else {
BaseVal = Frame->getTemporary(Base);
assert(BaseVal && "missing value for temporary");
}
// Volatile temporary objects cannot be accessed in constant expressions.
if (BaseType.isVolatileQualified()) {
if (Info.getLangOpts().CPlusPlus) {
Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
<< AK << 0;
Info.Note(Base->getExprLoc(), diag::note_constexpr_temporary_here);
} else {
Info.FFDiag(E);
}
return CompleteObject();
}
}
// During the construction of an object, it is not yet 'const'.
// FIXME: We don't set up EvaluatingDecl for local variables or temporaries,
// and this doesn't do quite the right thing for const subobjects of the
// object under construction.
if (LVal.getLValueBase() == Info.EvaluatingDecl) {
BaseType = Info.Ctx.getCanonicalType(BaseType);
BaseType.removeLocalConst();
}
// In C++1y, we can't safely access any mutable state when we might be
// evaluating after an unmodeled side effect.
//
// FIXME: Not all local state is mutable. Allow local constant subobjects
// to be read here (but take care with 'mutable' fields).
if ((Frame && Info.getLangOpts().CPlusPlus14 &&
Info.EvalStatus.HasSideEffects) ||
(AK != AK_Read && Info.IsSpeculativelyEvaluating))
return CompleteObject();
return CompleteObject(BaseVal, BaseType);
}
/// \brief Perform an lvalue-to-rvalue conversion on the given glvalue. This
/// can also be used for 'lvalue-to-lvalue' conversions for looking up the
/// glvalue referred to by an entity of reference type.
///
/// \param Info - Information about the ongoing evaluation.
/// \param Conv - The expression for which we are performing the conversion.
/// Used for diagnostics.
/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
/// case of a non-class type).
/// \param LVal - The glvalue on which we are attempting to perform this action.
/// \param RVal - The produced value will be placed here.
static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv,
QualType Type,
const LValue &LVal, APValue &RVal) {
if (LVal.Designator.Invalid)
return false;
// Check for special cases where there is no existing APValue to look at.
const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
if (Base && !LVal.CallIndex && !Type.isVolatileQualified()) {
if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
// In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
// initializer until now for such expressions. Such an expression can't be
// an ICE in C, so this only matters for fold.
if (Type.isVolatileQualified()) {
Info.FFDiag(Conv);
return false;
}
APValue Lit;
if (!Evaluate(Lit, Info, CLE->getInitializer()))
return false;
CompleteObject LitObj(&Lit, Base->getType());
return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal);
} else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
// We represent a string literal array as an lvalue pointing at the
// corresponding expression, rather than building an array of chars.
// FIXME: Support ObjCEncodeExpr, MakeStringConstant
APValue Str(Base, CharUnits::Zero(), APValue::NoLValuePath(), 0);
CompleteObject StrObj(&Str, Base->getType());
return extractSubobject(Info, Conv, StrObj, LVal.Designator, RVal);
}
}
CompleteObject Obj = findCompleteObject(Info, Conv, AK_Read, LVal, Type);
return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal);
}
/// Perform an assignment of Val to LVal. Takes ownership of Val.
static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
QualType LValType, APValue &Val) {
if (LVal.Designator.Invalid)
return false;
if (!Info.getLangOpts().CPlusPlus14) {
Info.FFDiag(E);
return false;
}
CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
}
static bool isOverflowingIntegerType(ASTContext &Ctx, QualType T) {
return T->isSignedIntegerType() &&
Ctx.getIntWidth(T) >= Ctx.getIntWidth(Ctx.IntTy);
}
namespace {
struct CompoundAssignSubobjectHandler {
EvalInfo &Info;
const Expr *E;
QualType PromotedLHSType;
BinaryOperatorKind Opcode;
const APValue &RHS;
static const AccessKinds AccessKind = AK_Assign;
typedef bool result_type;
bool checkConst(QualType QT) {
// Assigning to a const object has undefined behavior.
if (QT.isConstQualified()) {
Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
return false;
}
return true;
}
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) {
switch (Subobj.getKind()) {
case APValue::Int:
return found(Subobj.getInt(), SubobjType);
case APValue::Float:
return found(Subobj.getFloat(), SubobjType);
case APValue::ComplexInt:
case APValue::ComplexFloat:
// FIXME: Implement complex compound assignment.
Info.FFDiag(E);
return false;
case APValue::LValue:
return foundPointer(Subobj, SubobjType);
default:
// FIXME: can this happen?
Info.FFDiag(E);
return false;
}
}
bool found(APSInt &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
if (!SubobjType->isIntegerType() || !RHS.isInt()) {
// We don't support compound assignment on integer-cast-to-pointer
// values.
Info.FFDiag(E);
return false;
}
APSInt LHS = HandleIntToIntCast(Info, E, PromotedLHSType,
SubobjType, Value);
if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
return false;
Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
return true;
}
bool found(APFloat &Value, QualType SubobjType) {
return checkConst(SubobjType) &&
HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
Value) &&
handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
}
bool foundPointer(APValue &Subobj, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
QualType PointeeType;
if (const PointerType *PT = SubobjType->getAs<PointerType>())
PointeeType = PT->getPointeeType();
if (PointeeType.isNull() || !RHS.isInt() ||
(Opcode != BO_Add && Opcode != BO_Sub)) {
Info.FFDiag(E);
return false;
}
APSInt Offset = RHS.getInt();
if (Opcode == BO_Sub)
negateAsSigned(Offset);
LValue LVal;
LVal.setFrom(Info.Ctx, Subobj);
if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
return false;
LVal.moveInto(Subobj);
return true;
}
bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
llvm_unreachable("shouldn't encounter string elements here");
}
};
} // end anonymous namespace
const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
/// Perform a compound assignment of LVal <op>= RVal.
static bool handleCompoundAssignment(
EvalInfo &Info, const Expr *E,
const LValue &LVal, QualType LValType, QualType PromotedLValType,
BinaryOperatorKind Opcode, const APValue &RVal) {
if (LVal.Designator.Invalid)
return false;
if (!Info.getLangOpts().CPlusPlus14) {
Info.FFDiag(E);
return false;
}
CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
RVal };
return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
}
namespace {
struct IncDecSubobjectHandler {
EvalInfo &Info;
const Expr *E;
AccessKinds AccessKind;
APValue *Old;
typedef bool result_type;
bool checkConst(QualType QT) {
// Assigning to a const object has undefined behavior.
if (QT.isConstQualified()) {
Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
return false;
}
return true;
}
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) {
// Stash the old value. Also clear Old, so we don't clobber it later
// if we're post-incrementing a complex.
if (Old) {
*Old = Subobj;
Old = nullptr;
}
switch (Subobj.getKind()) {
case APValue::Int:
return found(Subobj.getInt(), SubobjType);
case APValue::Float:
return found(Subobj.getFloat(), SubobjType);
case APValue::ComplexInt:
return found(Subobj.getComplexIntReal(),
SubobjType->castAs<ComplexType>()->getElementType()
.withCVRQualifiers(SubobjType.getCVRQualifiers()));
case APValue::ComplexFloat:
return found(Subobj.getComplexFloatReal(),
SubobjType->castAs<ComplexType>()->getElementType()
.withCVRQualifiers(SubobjType.getCVRQualifiers()));
case APValue::LValue:
return foundPointer(Subobj, SubobjType);
default:
// FIXME: can this happen?
Info.FFDiag(E);
return false;
}
}
bool found(APSInt &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
if (!SubobjType->isIntegerType()) {
// We don't support increment / decrement on integer-cast-to-pointer
// values.
Info.FFDiag(E);
return false;
}
if (Old) *Old = APValue(Value);
// bool arithmetic promotes to int, and the conversion back to bool
// doesn't reduce mod 2^n, so special-case it.
if (SubobjType->isBooleanType()) {
if (AccessKind == AK_Increment)
Value = 1;
else
Value = !Value;
return true;
}
bool WasNegative = Value.isNegative();
if (AccessKind == AK_Increment) {
++Value;
if (!WasNegative && Value.isNegative() &&
isOverflowingIntegerType(Info.Ctx, SubobjType)) {
APSInt ActualValue(Value, /*IsUnsigned*/true);
return HandleOverflow(Info, E, ActualValue, SubobjType);
}
} else {
--Value;
if (WasNegative && !Value.isNegative() &&
isOverflowingIntegerType(Info.Ctx, SubobjType)) {
unsigned BitWidth = Value.getBitWidth();
APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
ActualValue.setBit(BitWidth);
return HandleOverflow(Info, E, ActualValue, SubobjType);
}
}
return true;
}
bool found(APFloat &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
if (Old) *Old = APValue(Value);
APFloat One(Value.getSemantics(), 1);
if (AccessKind == AK_Increment)
Value.add(One, APFloat::rmNearestTiesToEven);
else
Value.subtract(One, APFloat::rmNearestTiesToEven);
return true;
}
bool foundPointer(APValue &Subobj, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
QualType PointeeType;
if (const PointerType *PT = SubobjType->getAs<PointerType>())
PointeeType = PT->getPointeeType();
else {
Info.FFDiag(E);
return false;
}
LValue LVal;
LVal.setFrom(Info.Ctx, Subobj);
if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
AccessKind == AK_Increment ? 1 : -1))
return false;
LVal.moveInto(Subobj);
return true;
}
bool foundString(APValue &Subobj, QualType SubobjType, uint64_t Character) {
llvm_unreachable("shouldn't encounter string elements here");
}
};
} // end anonymous namespace
/// Perform an increment or decrement on LVal.
static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
QualType LValType, bool IsIncrement, APValue *Old) {
if (LVal.Designator.Invalid)
return false;
if (!Info.getLangOpts().CPlusPlus14) {
Info.FFDiag(E);
return false;
}
AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
IncDecSubobjectHandler Handler = { Info, E, AK, Old };
return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
}
/// Build an lvalue for the object argument of a member function call.
static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
LValue &This) {
if (Object->getType()->isPointerType())
return EvaluatePointer(Object, This, Info);
if (Object->isGLValue())
return EvaluateLValue(Object, This, Info);
if (Object->getType()->isLiteralType(Info.Ctx))
return EvaluateTemporary(Object, This, Info);
Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
return false;
}
/// HandleMemberPointerAccess - Evaluate a member access operation and build an
/// lvalue referring to the result.
///
/// \param Info - Information about the ongoing evaluation.
/// \param LV - An lvalue referring to the base of the member pointer.
/// \param RHS - The member pointer expression.
/// \param IncludeMember - Specifies whether the member itself is included in
/// the resulting LValue subobject designator. This is not possible when
/// creating a bound member function.
/// \return The field or method declaration to which the member pointer refers,
/// or 0 if evaluation fails.
static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
QualType LVType,
LValue &LV,
const Expr *RHS,
bool IncludeMember = true) {
MemberPtr MemPtr;
if (!EvaluateMemberPointer(RHS, MemPtr, Info))
return nullptr;
// C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
// member value, the behavior is undefined.
if (!MemPtr.getDecl()) {
// FIXME: Specific diagnostic.
Info.FFDiag(RHS);
return nullptr;
}
if (MemPtr.isDerivedMember()) {
// This is a member of some derived class. Truncate LV appropriately.
// The end of the derived-to-base path for the base object must match the
// derived-to-base path for the member pointer.
if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
LV.Designator.Entries.size()) {
Info.FFDiag(RHS);
return nullptr;
}
unsigned PathLengthToMember =
LV.Designator.Entries.size() - MemPtr.Path.size();
for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
const CXXRecordDecl *LVDecl = getAsBaseClass(
LV.Designator.Entries[PathLengthToMember + I]);
const CXXRecordDecl *MPDecl = MemPtr.Path[I];
if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
Info.FFDiag(RHS);
return nullptr;
}
}
// Truncate the lvalue to the appropriate derived class.
if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
PathLengthToMember))
return nullptr;
} else if (!MemPtr.Path.empty()) {
// Extend the LValue path with the member pointer's path.
LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
MemPtr.Path.size() + IncludeMember);
// Walk down to the appropriate base class.
if (const PointerType *PT = LVType->getAs<PointerType>())
LVType = PT->getPointeeType();
const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
assert(RD && "member pointer access on non-class-type expression");
// The first class in the path is that of the lvalue.
for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
return nullptr;
RD = Base;
}
// Finally cast to the class containing the member.
if (!HandleLValueDirectBase(Info, RHS, LV, RD,
MemPtr.getContainingRecord()))
return nullptr;
}
// Add the member. Note that we cannot build bound member functions here.
if (IncludeMember) {
if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
if (!HandleLValueMember(Info, RHS, LV, FD))
return nullptr;
} else if (const IndirectFieldDecl *IFD =
dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
return nullptr;
} else {
llvm_unreachable("can't construct reference to bound member function");
}
}
return MemPtr.getDecl();
}
static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
const BinaryOperator *BO,
LValue &LV,
bool IncludeMember = true) {
assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI);
if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
if (Info.noteFailure()) {
MemberPtr MemPtr;
EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
}
return nullptr;
}
return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
BO->getRHS(), IncludeMember);
}
/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
/// the provided lvalue, which currently refers to the base object.
static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
LValue &Result) {
SubobjectDesignator &D = Result.Designator;
if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
return false;
QualType TargetQT = E->getType();
if (const PointerType *PT = TargetQT->getAs<PointerType>())
TargetQT = PT->getPointeeType();
// Check this cast lands within the final derived-to-base subobject path.
if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
<< D.MostDerivedType << TargetQT;
return false;
}
// Check the type of the final cast. We don't need to check the path,
// since a cast can only be formed if the path is unique.
unsigned NewEntriesSize = D.Entries.size() - E->path_size();
const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
const CXXRecordDecl *FinalType;
if (NewEntriesSize == D.MostDerivedPathLength)
FinalType = D.MostDerivedType->getAsCXXRecordDecl();
else
FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
<< D.MostDerivedType << TargetQT;
return false;
}
// Truncate the lvalue to the appropriate derived class.
return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
}
namespace {
enum EvalStmtResult {
/// Evaluation failed.
ESR_Failed,
/// Hit a 'return' statement.
ESR_Returned,
/// Evaluation succeeded.
ESR_Succeeded,
/// Hit a 'continue' statement.
ESR_Continue,
/// Hit a 'break' statement.
ESR_Break,
/// Still scanning for 'case' or 'default' statement.
ESR_CaseNotFound
};
}
static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
// We don't need to evaluate the initializer for a static local.
if (!VD->hasLocalStorage())
return true;
LValue Result;
Result.set(VD, Info.CurrentCall->Index);
APValue &Val = Info.CurrentCall->createTemporary(VD, true);
const Expr *InitE = VD->getInit();
if (!InitE) {
Info.FFDiag(VD->getLocStart(), diag::note_constexpr_uninitialized)
<< false << VD->getType();
Val = APValue();
return false;
}
if (InitE->isValueDependent())
return false;
if (!EvaluateInPlace(Val, Info, Result, InitE)) {
// Wipe out any partially-computed value, to allow tracking that this
// evaluation failed.
Val = APValue();
return false;
}
return true;
}
static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
bool OK = true;
if (const VarDecl *VD = dyn_cast<VarDecl>(D))
OK &= EvaluateVarDecl(Info, VD);
if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
for (auto *BD : DD->bindings())
if (auto *VD = BD->getHoldingVar())
OK &= EvaluateDecl(Info, VD);
return OK;
}
/// Evaluate a condition (either a variable declaration or an expression).
static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
const Expr *Cond, bool &Result) {
FullExpressionRAII Scope(Info);
if (CondDecl && !EvaluateDecl(Info, CondDecl))
return false;
return EvaluateAsBooleanCondition(Cond, Result, Info);
}
namespace {
/// \brief A location where the result (returned value) of evaluating a
/// statement should be stored.
struct StmtResult {
/// The APValue that should be filled in with the returned value.
APValue &Value;
/// The location containing the result, if any (used to support RVO).
const LValue *Slot;
};
}
static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
const Stmt *S,
const SwitchCase *SC = nullptr);
/// Evaluate the body of a loop, and translate the result as appropriate.
static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
const Stmt *Body,
const SwitchCase *Case = nullptr) {
BlockScopeRAII Scope(Info);
switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case)) {
case ESR_Break:
return ESR_Succeeded;
case ESR_Succeeded:
case ESR_Continue:
return ESR_Continue;
case ESR_Failed:
case ESR_Returned:
case ESR_CaseNotFound:
return ESR;
}
llvm_unreachable("Invalid EvalStmtResult!");
}
/// Evaluate a switch statement.
static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
const SwitchStmt *SS) {
BlockScopeRAII Scope(Info);
// Evaluate the switch condition.
APSInt Value;
{
FullExpressionRAII Scope(Info);
if (const Stmt *Init = SS->getInit()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
if (ESR != ESR_Succeeded)
return ESR;
}
if (SS->getConditionVariable() &&
!EvaluateDecl(Info, SS->getConditionVariable()))
return ESR_Failed;
if (!EvaluateInteger(SS->getCond(), Value, Info))
return ESR_Failed;
}
// Find the switch case corresponding to the value of the condition.
// FIXME: Cache this lookup.
const SwitchCase *Found = nullptr;
for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
SC = SC->getNextSwitchCase()) {
if (isa<DefaultStmt>(SC)) {
Found = SC;
continue;
}
const CaseStmt *CS = cast<CaseStmt>(SC);
APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
: LHS;
if (LHS <= Value && Value <= RHS) {
Found = SC;
break;
}
}
if (!Found)
return ESR_Succeeded;
// Search the switch body for the switch case and evaluate it from there.
switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found)) {
case ESR_Break:
return ESR_Succeeded;
case ESR_Succeeded:
case ESR_Continue:
case ESR_Failed:
case ESR_Returned:
return ESR;
case ESR_CaseNotFound:
// This can only happen if the switch case is nested within a statement
// expression. We have no intention of supporting that.
Info.FFDiag(Found->getLocStart(), diag::note_constexpr_stmt_expr_unsupported);
return ESR_Failed;
}
llvm_unreachable("Invalid EvalStmtResult!");
}
// Evaluate a statement.
static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
const Stmt *S, const SwitchCase *Case) {
if (!Info.nextStep(S))
return ESR_Failed;
// If we're hunting down a 'case' or 'default' label, recurse through
// substatements until we hit the label.
if (Case) {
// FIXME: We don't start the lifetime of objects whose initialization we
// jump over. However, such objects must be of class type with a trivial
// default constructor that initialize all subobjects, so must be empty,
// so this almost never matters.
switch (S->getStmtClass()) {
case Stmt::CompoundStmtClass:
// FIXME: Precompute which substatement of a compound statement we
// would jump to, and go straight there rather than performing a
// linear scan each time.
case Stmt::LabelStmtClass:
case Stmt::AttributedStmtClass:
case Stmt::DoStmtClass:
break;
case Stmt::CaseStmtClass:
case Stmt::DefaultStmtClass:
if (Case == S)
Case = nullptr;
break;
case Stmt::IfStmtClass: {
// FIXME: Precompute which side of an 'if' we would jump to, and go
// straight there rather than scanning both sides.
const IfStmt *IS = cast<IfStmt>(S);
// Wrap the evaluation in a block scope, in case it's a DeclStmt
// preceded by our switch label.
BlockScopeRAII Scope(Info);
EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
if (ESR != ESR_CaseNotFound || !IS->getElse())
return ESR;
return EvaluateStmt(Result, Info, IS->getElse(), Case);
}
case Stmt::WhileStmtClass: {
EvalStmtResult ESR =
EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
if (ESR != ESR_Continue)
return ESR;
break;
}
case Stmt::ForStmtClass: {
const ForStmt *FS = cast<ForStmt>(S);
EvalStmtResult ESR =
EvaluateLoopBody(Result, Info, FS->getBody(), Case);
if (ESR != ESR_Continue)
return ESR;
if (FS->getInc()) {
FullExpressionRAII IncScope(Info);
if (!EvaluateIgnoredValue(Info, FS->getInc()))
return ESR_Failed;
}
break;
}
case Stmt::DeclStmtClass:
// FIXME: If the variable has initialization that can't be jumped over,
// bail out of any immediately-surrounding compound-statement too.
default:
return ESR_CaseNotFound;
}
}
switch (S->getStmtClass()) {
default:
if (const Expr *E = dyn_cast<Expr>(S)) {
// Don't bother evaluating beyond an expression-statement which couldn't
// be evaluated.
FullExpressionRAII Scope(Info);
if (!EvaluateIgnoredValue(Info, E))
return ESR_Failed;
return ESR_Succeeded;
}
Info.FFDiag(S->getLocStart());
return ESR_Failed;
case Stmt::NullStmtClass:
return ESR_Succeeded;
case Stmt::DeclStmtClass: {
const DeclStmt *DS = cast<DeclStmt>(S);
for (const auto *DclIt : DS->decls()) {
// Each declaration initialization is its own full-expression.
// FIXME: This isn't quite right; if we're performing aggregate
// initialization, each braced subexpression is its own full-expression.
FullExpressionRAII Scope(Info);
if (!EvaluateDecl(Info, DclIt) && !Info.noteFailure())
return ESR_Failed;
}
return ESR_Succeeded;
}
case Stmt::ReturnStmtClass: {
const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
FullExpressionRAII Scope(Info);
if (RetExpr &&
!(Result.Slot
? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
: Evaluate(Result.Value, Info, RetExpr)))
return ESR_Failed;
return ESR_Returned;
}
case Stmt::CompoundStmtClass: {
BlockScopeRAII Scope(Info);
const CompoundStmt *CS = cast<CompoundStmt>(S);
for (const auto *BI : CS->body()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
if (ESR == ESR_Succeeded)
Case = nullptr;
else if (ESR != ESR_CaseNotFound)
return ESR;
}
return Case ? ESR_CaseNotFound : ESR_Succeeded;
}
case Stmt::IfStmtClass: {
const IfStmt *IS = cast<IfStmt>(S);
// Evaluate the condition, as either a var decl or as an expression.
BlockScopeRAII Scope(Info);
if (const Stmt *Init = IS->getInit()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
if (ESR != ESR_Succeeded)
return ESR;
}
bool Cond;
if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond))
return ESR_Failed;
if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
if (ESR != ESR_Succeeded)
return ESR;
}
return ESR_Succeeded;
}
case Stmt::WhileStmtClass: {
const WhileStmt *WS = cast<WhileStmt>(S);
while (true) {
BlockScopeRAII Scope(Info);
bool Continue;
if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
Continue))
return ESR_Failed;
if (!Continue)
break;
EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
if (ESR != ESR_Continue)
return ESR;
}
return ESR_Succeeded;
}
case Stmt::DoStmtClass: {
const DoStmt *DS = cast<DoStmt>(S);
bool Continue;
do {
EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
if (ESR != ESR_Continue)
return ESR;
Case = nullptr;
FullExpressionRAII CondScope(Info);
if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info))
return ESR_Failed;
} while (Continue);
return ESR_Succeeded;
}
case Stmt::ForStmtClass: {
const ForStmt *FS = cast<ForStmt>(S);
BlockScopeRAII Scope(Info);
if (FS->getInit()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
if (ESR != ESR_Succeeded)
return ESR;
}
while (true) {
BlockScopeRAII Scope(Info);
bool Continue = true;
if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
FS->getCond(), Continue))
return ESR_Failed;
if (!Continue)
break;
EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
if (ESR != ESR_Continue)
return ESR;
if (FS->getInc()) {
FullExpressionRAII IncScope(Info);
if (!EvaluateIgnoredValue(Info, FS->getInc()))
return ESR_Failed;
}
}
return ESR_Succeeded;
}
case Stmt::CXXForRangeStmtClass: {
const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
BlockScopeRAII Scope(Info);
// Initialize the __range variable.
EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
if (ESR != ESR_Succeeded)
return ESR;
// Create the __begin and __end iterators.
ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
if (ESR != ESR_Succeeded)
return ESR;
ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
if (ESR != ESR_Succeeded)
return ESR;
while (true) {
// Condition: __begin != __end.
{
bool Continue = true;
FullExpressionRAII CondExpr(Info);
if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
return ESR_Failed;
if (!Continue)
break;
}
// User's variable declaration, initialized by *__begin.
BlockScopeRAII InnerScope(Info);
ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
if (ESR != ESR_Succeeded)
return ESR;
// Loop body.
ESR = EvaluateLoopBody(Result, Info, FS->getBody());
if (ESR != ESR_Continue)
return ESR;
// Increment: ++__begin
if (!EvaluateIgnoredValue(Info, FS->getInc()))
return ESR_Failed;
}
return ESR_Succeeded;
}
case Stmt::SwitchStmtClass:
return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
case Stmt::ContinueStmtClass:
return ESR_Continue;
case Stmt::BreakStmtClass:
return ESR_Break;
case Stmt::LabelStmtClass:
return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
case Stmt::AttributedStmtClass:
// As a general principle, C++11 attributes can be ignored without
// any semantic impact.
return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
Case);
case Stmt::CaseStmtClass:
case Stmt::DefaultStmtClass:
return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
}
}
/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
/// default constructor. If so, we'll fold it whether or not it's marked as
/// constexpr. If it is marked as constexpr, we will never implicitly define it,
/// so we need special handling.
static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
const CXXConstructorDecl *CD,
bool IsValueInitialization) {
if (!CD->isTrivial() || !CD->isDefaultConstructor())
return false;
// Value-initialization does not call a trivial default constructor, so such a
// call is a core constant expression whether or not the constructor is
// constexpr.
if (!CD->isConstexpr() && !IsValueInitialization) {
if (Info.getLangOpts().CPlusPlus11) {
// FIXME: If DiagDecl is an implicitly-declared special member function,
// we should be much more explicit about why it's not constexpr.
Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
<< /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
Info.Note(CD->getLocation(), diag::note_declared_at);
} else {
Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
}
}
return true;
}
/// CheckConstexprFunction - Check that a function can be called in a constant
/// expression.
static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
const FunctionDecl *Declaration,
const FunctionDecl *Definition,
const Stmt *Body) {
// Potential constant expressions can contain calls to declared, but not yet
// defined, constexpr functions.
if (Info.checkingPotentialConstantExpression() && !Definition &&
Declaration->isConstexpr())
return false;
// Bail out with no diagnostic if the function declaration itself is invalid.
// We will have produced a relevant diagnostic while parsing it.
if (Declaration->isInvalidDecl())
return false;
// Can we evaluate this function call?
if (Definition && Definition->isConstexpr() &&
!Definition->isInvalidDecl() && Body)
return true;
if (Info.getLangOpts().CPlusPlus11) {
const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
// If this function is not constexpr because it is an inherited
// non-constexpr constructor, diagnose that directly.
auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
if (CD && CD->isInheritingConstructor()) {
auto *Inherited = CD->getInheritedConstructor().getConstructor();
if (!Inherited->isConstexpr())
DiagDecl = CD = Inherited;
}
// FIXME: If DiagDecl is an implicitly-declared special member function
// or an inheriting constructor, we should be much more explicit about why
// it's not constexpr.
if (CD && CD->isInheritingConstructor())
Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
<< CD->getInheritedConstructor().getConstructor()->getParent();
else
Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
<< DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
} else {
Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
}
return false;
}
/// Determine if a class has any fields that might need to be copied by a
/// trivial copy or move operation.
static bool hasFields(const CXXRecordDecl *RD) {
if (!RD || RD->isEmpty())
return false;
for (auto *FD : RD->fields()) {
if (FD->isUnnamedBitfield())
continue;
return true;
}
for (auto &Base : RD->bases())
if (hasFields(Base.getType()->getAsCXXRecordDecl()))
return true;
return false;
}
namespace {
typedef SmallVector<APValue, 8> ArgVector;
}
/// EvaluateArgs - Evaluate the arguments to a function call.
static bool EvaluateArgs(ArrayRef<const Expr*> Args, ArgVector &ArgValues,
EvalInfo &Info) {
bool Success = true;
for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
I != E; ++I) {
if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) {
// If we're checking for a potential constant expression, evaluate all
// initializers even if some of them fail.
if (!Info.noteFailure())
return false;
Success = false;
}
}
return Success;
}
/// Evaluate a function call.
static bool HandleFunctionCall(SourceLocation CallLoc,
const FunctionDecl *Callee, const LValue *This,
ArrayRef<const Expr*> Args, const Stmt *Body,
EvalInfo &Info, APValue &Result,
const LValue *ResultSlot) {
ArgVector ArgValues(Args.size());
if (!EvaluateArgs(Args, ArgValues, Info))
return false;
if (!Info.CheckCallLimit(CallLoc))
return false;
CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data());
// For a trivial copy or move assignment, perform an APValue copy. This is
// essential for unions, where the operations performed by the assignment
// operator cannot be represented as statements.
//
// Skip this for non-union classes with no fields; in that case, the defaulted
// copy/move does not actually read the object.
const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee);
if (MD && MD->isDefaulted() &&
(MD->getParent()->isUnion() ||
(MD->isTrivial() && hasFields(MD->getParent())))) {
assert(This &&
(MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()));
LValue RHS;
RHS.setFrom(Info.Ctx, ArgValues[0]);
APValue RHSValue;
if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(),
RHS, RHSValue))
return false;
if (!handleAssignment(Info, Args[0], *This, MD->getThisType(Info.Ctx),
RHSValue))
return false;
This->moveInto(Result);
return true;
} else if (MD && isLambdaCallOperator(MD)) {
// We're in a lambda; determine the lambda capture field maps.
MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields,
Frame.LambdaThisCaptureField);
}
StmtResult Ret = {Result, ResultSlot};
EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body);
if (ESR == ESR_Succeeded) {
if (Callee->getReturnType()->isVoidType())
return true;
Info.FFDiag(Callee->getLocEnd(), diag::note_constexpr_no_return);
}
return ESR == ESR_Returned;
}
/// Evaluate a constructor call.
static bool HandleConstructorCall(const Expr *E, const LValue &This,
APValue *ArgValues,
const CXXConstructorDecl *Definition,
EvalInfo &Info, APValue &Result) {
SourceLocation CallLoc = E->getExprLoc();
if (!Info.CheckCallLimit(CallLoc))
return false;
const CXXRecordDecl *RD = Definition->getParent();
if (RD->getNumVBases()) {
Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
return false;
}
CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues);
// FIXME: Creating an APValue just to hold a nonexistent return value is
// wasteful.
APValue RetVal;
StmtResult Ret = {RetVal, nullptr};
// If it's a delegating constructor, delegate.
if (Definition->isDelegatingConstructor()) {
CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
{
FullExpressionRAII InitScope(Info);
if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()))
return false;
}
return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
}
// For a trivial copy or move constructor, perform an APValue copy. This is
// essential for unions (or classes with anonymous union members), where the
// operations performed by the constructor cannot be represented by
// ctor-initializers.
//
// Skip this for empty non-union classes; we should not perform an
// lvalue-to-rvalue conversion on them because their copy constructor does not
// actually read them.
if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() &&
(Definition->getParent()->isUnion() ||
(Definition->isTrivial() && hasFields(Definition->getParent())))) {
LValue RHS;
RHS.setFrom(Info.Ctx, ArgValues[0]);
return handleLValueToRValueConversion(
Info, E, Definition->getParamDecl(0)->getType().getNonReferenceType(),
RHS, Result);
}
// Reserve space for the struct members.
if (!RD->isUnion() && Result.isUninit())
Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
std::distance(RD->field_begin(), RD->field_end()));
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
// A scope for temporaries lifetime-extended by reference members.
BlockScopeRAII LifetimeExtendedScope(Info);
bool Success = true;
unsigned BasesSeen = 0;
#ifndef NDEBUG
CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin();
#endif
for (const auto *I : Definition->inits()) {
LValue Subobject = This;
APValue *Value = &Result;
// Determine the subobject to initialize.
FieldDecl *FD = nullptr;
if (I->isBaseInitializer()) {
QualType BaseType(I->getBaseClass(), 0);
#ifndef NDEBUG
// Non-virtual base classes are initialized in the order in the class
// definition. We have already checked for virtual base classes.
assert(!BaseIt->isVirtual() && "virtual base for literal type");
assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
"base class initializers not in expected order");
++BaseIt;
#endif
if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD,
BaseType->getAsCXXRecordDecl(), &Layout))
return false;
Value = &Result.getStructBase(BasesSeen++);
} else if ((FD = I->getMember())) {
if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout))
return false;
if (RD->isUnion()) {
Result = APValue(FD);
Value = &Result.getUnionValue();
} else {
Value = &Result.getStructField(FD->getFieldIndex());
}
} else if (IndirectFieldDecl *IFD = I->getIndirectMember()) {
// Walk the indirect field decl's chain to find the object to initialize,
// and make sure we've initialized every step along it.
for (auto *C : IFD->chain()) {
FD = cast<FieldDecl>(C);
CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent());
// Switch the union field if it differs. This happens if we had
// preceding zero-initialization, and we're now initializing a union
// subobject other than the first.
// FIXME: In this case, the values of the other subobjects are
// specified, since zero-initialization sets all padding bits to zero.
if (Value->isUninit() ||
(Value->isUnion() && Value->getUnionField() != FD)) {
if (CD->isUnion())
*Value = APValue(FD);
else
*Value = APValue(APValue::UninitStruct(), CD->getNumBases(),
std::distance(CD->field_begin(), CD->field_end()));
}
if (!HandleLValueMember(Info, I->getInit(), Subobject, FD))
return false;
if (CD->isUnion())
Value = &Value->getUnionValue();
else
Value = &Value->getStructField(FD->getFieldIndex());
}
} else {
llvm_unreachable("unknown base initializer kind");
}
FullExpressionRAII InitScope(Info);
if (!EvaluateInPlace(*Value, Info, Subobject, I->getInit()) ||
(FD && FD->isBitField() && !truncateBitfieldValue(Info, I->getInit(),
*Value, FD))) {
// If we're checking for a potential constant expression, evaluate all
// initializers even if some of them fail.
if (!Info.noteFailure())
return false;
Success = false;
}
}
return Success &&
EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
}
static bool HandleConstructorCall(const Expr *E, const LValue &This,
ArrayRef<const Expr*> Args,
const CXXConstructorDecl *Definition,
EvalInfo &Info, APValue &Result) {
ArgVector ArgValues(Args.size());
if (!EvaluateArgs(Args, ArgValues, Info))
return false;
return HandleConstructorCall(E, This, ArgValues.data(), Definition,
Info, Result);
}
//===----------------------------------------------------------------------===//
// Generic Evaluation
//===----------------------------------------------------------------------===//
namespace {
template <class Derived>
class ExprEvaluatorBase
: public ConstStmtVisitor<Derived, bool> {
private:
Derived &getDerived() { return static_cast<Derived&>(*this); }
bool DerivedSuccess(const APValue &V, const Expr *E) {
return getDerived().Success(V, E);
}
bool DerivedZeroInitialization(const Expr *E) {
return getDerived().ZeroInitialization(E);
}
// Check whether a conditional operator with a non-constant condition is a
// potential constant expression. If neither arm is a potential constant
// expression, then the conditional operator is not either.
template<typename ConditionalOperator>
void CheckPotentialConstantConditional(const ConditionalOperator *E) {
assert(Info.checkingPotentialConstantExpression());
// Speculatively evaluate both arms.
SmallVector<PartialDiagnosticAt, 8> Diag;
{
SpeculativeEvaluationRAII Speculate(Info, &Diag);
StmtVisitorTy::Visit(E->getFalseExpr());
if (Diag.empty())
return;
}
{
SpeculativeEvaluationRAII Speculate(Info, &Diag);
Diag.clear();
StmtVisitorTy::Visit(E->getTrueExpr());
if (Diag.empty())
return;
}
Error(E, diag::note_constexpr_conditional_never_const);
}
template<typename ConditionalOperator>
bool HandleConditionalOperator(const ConditionalOperator *E) {
bool BoolResult;
if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) {
if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) {
CheckPotentialConstantConditional(E);
return false;
}
if (Info.noteFailure()) {
StmtVisitorTy::Visit(E->getTrueExpr());
StmtVisitorTy::Visit(E->getFalseExpr());
}
return false;
}
Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
return StmtVisitorTy::Visit(EvalExpr);
}
protected:
EvalInfo &Info;
typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy;
typedef ExprEvaluatorBase ExprEvaluatorBaseTy;
OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
return Info.CCEDiag(E, D);
}
bool ZeroInitialization(const Expr *E) { return Error(E); }
public:
ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {}
EvalInfo &getEvalInfo() { return Info; }
/// Report an evaluation error. This should only be called when an error is
/// first discovered. When propagating an error, just return false.
bool Error(const Expr *E, diag::kind D) {
Info.FFDiag(E, D);
return false;
}
bool Error(const Expr *E) {
return Error(E, diag::note_invalid_subexpr_in_const_expr);
}
bool VisitStmt(const Stmt *) {
llvm_unreachable("Expression evaluator should not be called on stmts");
}
bool VisitExpr(const Expr *E) {
return Error(E);
}
bool VisitParenExpr(const ParenExpr *E)
{ return StmtVisitorTy::Visit(E->getSubExpr()); }
bool VisitUnaryExtension(const UnaryOperator *E)
{ return StmtVisitorTy::Visit(E->getSubExpr()); }
bool VisitUnaryPlus(const UnaryOperator *E)
{ return StmtVisitorTy::Visit(E->getSubExpr()); }
bool VisitChooseExpr(const ChooseExpr *E)
{ return StmtVisitorTy::Visit(E->getChosenSubExpr()); }
bool VisitGenericSelectionExpr(const GenericSelectionExpr *E)
{ return StmtVisitorTy::Visit(E->getResultExpr()); }
bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E)
{ return StmtVisitorTy::Visit(E->getReplacement()); }
bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E)
{ return StmtVisitorTy::Visit(E->getExpr()); }
bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) {
// The initializer may not have been parsed yet, or might be erroneous.
if (!E->getExpr())
return Error(E);
return StmtVisitorTy::Visit(E->getExpr());
}
// We cannot create any objects for which cleanups are required, so there is
// nothing to do here; all cleanups must come from unevaluated subexpressions.
bool VisitExprWithCleanups(const ExprWithCleanups *E)
{ return StmtVisitorTy::Visit(E->getSubExpr()); }
bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) {
CCEDiag(E, diag::note_constexpr_invalid_cast) << 0;
return static_cast<Derived*>(this)->VisitCastExpr(E);
}
bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) {
CCEDiag(E, diag::note_constexpr_invalid_cast) << 1;
return static_cast<Derived*>(this)->VisitCastExpr(E);
}
bool VisitBinaryOperator(const BinaryOperator *E) {
switch (E->getOpcode()) {
default:
return Error(E);
case BO_Comma:
VisitIgnoredValue(E->getLHS());
return StmtVisitorTy::Visit(E->getRHS());
case BO_PtrMemD:
case BO_PtrMemI: {
LValue Obj;
if (!HandleMemberPointerAccess(Info, E, Obj))
return false;
APValue Result;
if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result))
return false;
return DerivedSuccess(Result, E);
}
}
}
bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) {
// Evaluate and cache the common expression. We treat it as a temporary,
// even though it's not quite the same thing.
if (!Evaluate(Info.CurrentCall->createTemporary(E->getOpaqueValue(), false),
Info, E->getCommon()))
return false;
return HandleConditionalOperator(E);
}
bool VisitConditionalOperator(const ConditionalOperator *E) {
bool IsBcpCall = false;
// If the condition (ignoring parens) is a __builtin_constant_p call,
// the result is a constant expression if it can be folded without
// side-effects. This is an important GNU extension. See GCC PR38377
// for discussion.
if (const CallExpr *CallCE =
dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts()))
if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
IsBcpCall = true;
// Always assume __builtin_constant_p(...) ? ... : ... is a potential
// constant expression; we can't check whether it's potentially foldable.
if (Info.checkingPotentialConstantExpression() && IsBcpCall)
return false;
FoldConstant Fold(Info, IsBcpCall);
if (!HandleConditionalOperator(E)) {
Fold.keepDiagnostics();
return false;
}
return true;
}
bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) {
if (APValue *Value = Info.CurrentCall->getTemporary(E))
return DerivedSuccess(*Value, E);
const Expr *Source = E->getSourceExpr();
if (!Source)
return Error(E);
if (Source == E) { // sanity checking.
assert(0 && "OpaqueValueExpr recursively refers to itself");
return Error(E);
}
return StmtVisitorTy::Visit(Source);
}
bool VisitCallExpr(const CallExpr *E) {
APValue Result;
if (!handleCallExpr(E, Result, nullptr))
return false;
return DerivedSuccess(Result, E);
}
bool handleCallExpr(const CallExpr *E, APValue &Result,
const LValue *ResultSlot) {
const Expr *Callee = E->getCallee()->IgnoreParens();
QualType CalleeType = Callee->getType();
const FunctionDecl *FD = nullptr;
LValue *This = nullptr, ThisVal;
auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
bool HasQualifier = false;
// Extract function decl and 'this' pointer from the callee.
if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) {
const ValueDecl *Member = nullptr;
if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) {
// Explicit bound member calls, such as x.f() or p->g();
if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal))
return false;
Member = ME->getMemberDecl();
This = &ThisVal;
HasQualifier = ME->hasQualifier();
} else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) {
// Indirect bound member calls ('.*' or '->*').
Member = HandleMemberPointerAccess(Info, BE, ThisVal, false);
if (!Member) return false;
This = &ThisVal;
} else
return Error(Callee);
FD = dyn_cast<FunctionDecl>(Member);
if (!FD)
return Error(Callee);
} else if (CalleeType->isFunctionPointerType()) {
LValue Call;
if (!EvaluatePointer(Callee, Call, Info))
return false;
if (!Call.getLValueOffset().isZero())
return Error(Callee);
FD = dyn_cast_or_null<FunctionDecl>(
Call.getLValueBase().dyn_cast<const ValueDecl*>());
if (!FD)
return Error(Callee);
// Don't call function pointers which have been cast to some other type.
// Per DR (no number yet), the caller and callee can differ in noexcept.
if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
CalleeType->getPointeeType(), FD->getType())) {
return Error(E);
}
// Overloaded operator calls to member functions are represented as normal
// calls with '*this' as the first argument.
const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
if (MD && !MD->isStatic()) {
// FIXME: When selecting an implicit conversion for an overloaded
// operator delete, we sometimes try to evaluate calls to conversion
// operators without a 'this' parameter!
if (Args.empty())
return Error(E);
if (!EvaluateObjectArgument(Info, Args[0], ThisVal))
return false;
This = &ThisVal;
Args = Args.slice(1);
} else if (MD && MD->isLambdaStaticInvoker()) {
// Map the static invoker for the lambda back to the call operator.
// Conveniently, we don't have to slice out the 'this' argument (as is
// being done for the non-static case), since a static member function
// doesn't have an implicit argument passed in.
const CXXRecordDecl *ClosureClass = MD->getParent();
assert(
ClosureClass->captures_begin() == ClosureClass->captures_end() &&
"Number of captures must be zero for conversion to function-ptr");
const CXXMethodDecl *LambdaCallOp =
ClosureClass->getLambdaCallOperator();
// Set 'FD', the function that will be called below, to the call
// operator. If the closure object represents a generic lambda, find
// the corresponding specialization of the call operator.
if (ClosureClass->isGenericLambda()) {
assert(MD->isFunctionTemplateSpecialization() &&
"A generic lambda's static-invoker function must be a "
"template specialization");
const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
FunctionTemplateDecl *CallOpTemplate =
LambdaCallOp->getDescribedFunctionTemplate();
void *InsertPos = nullptr;
FunctionDecl *CorrespondingCallOpSpecialization =
CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
assert(CorrespondingCallOpSpecialization &&
"We must always have a function call operator specialization "
"that corresponds to our static invoker specialization");
FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
} else
FD = LambdaCallOp;
}
} else
return Error(E);
if (This && !This->checkSubobject(Info, E, CSK_This))
return false;
// DR1358 allows virtual constexpr functions in some cases. Don't allow
// calls to such functions in constant expressions.
if (This && !HasQualifier &&
isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isVirtual())
return Error(E, diag::note_constexpr_virtual_call);
const FunctionDecl *Definition = nullptr;
Stmt *Body = FD->getBody(Definition);
if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) ||
!HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, Info,
Result, ResultSlot))
return false;
return true;
}
bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
return StmtVisitorTy::Visit(E->getInitializer());
}
bool VisitInitListExpr(const InitListExpr *E) {
if (E->getNumInits() == 0)
return DerivedZeroInitialization(E);
if (E->getNumInits() == 1)
return StmtVisitorTy::Visit(E->getInit(0));
return Error(E);
}
bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
return DerivedZeroInitialization(E);
}
bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) {
return DerivedZeroInitialization(E);
}
bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) {
return DerivedZeroInitialization(E);
}
/// A member expression where the object is a prvalue is itself a prvalue.
bool VisitMemberExpr(const MemberExpr *E) {
assert(!E->isArrow() && "missing call to bound member function?");
APValue Val;
if (!Evaluate(Val, Info, E->getBase()))
return false;
QualType BaseTy = E->getBase()->getType();
const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
if (!FD) return Error(E);
assert(!FD->getType()->isReferenceType() && "prvalue reference?");
assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
FD->getParent()->getCanonicalDecl() && "record / field mismatch");
CompleteObject Obj(&Val, BaseTy);
SubobjectDesignator Designator(BaseTy);
Designator.addDeclUnchecked(FD);
APValue Result;
return extractSubobject(Info, E, Obj, Designator, Result) &&
DerivedSuccess(Result, E);
}
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
break;
case CK_AtomicToNonAtomic: {
APValue AtomicVal;
// This does not need to be done in place even for class/array types:
// atomic-to-non-atomic conversion implies copying the object
// representation.
if (!Evaluate(AtomicVal, Info, E->getSubExpr()))
return false;
return DerivedSuccess(AtomicVal, E);
}
case CK_NoOp:
case CK_UserDefinedConversion:
return StmtVisitorTy::Visit(E->getSubExpr());
case CK_LValueToRValue: {
LValue LVal;
if (!EvaluateLValue(E->getSubExpr(), LVal, Info))
return false;
APValue RVal;
// Note, we use the subexpression's type in order to retain cv-qualifiers.
if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
LVal, RVal))
return false;
return DerivedSuccess(RVal, E);
}
}
return Error(E);
}
bool VisitUnaryPostInc(const UnaryOperator *UO) {
return VisitUnaryPostIncDec(UO);
}
bool VisitUnaryPostDec(const UnaryOperator *UO) {
return VisitUnaryPostIncDec(UO);
}
bool VisitUnaryPostIncDec(const UnaryOperator *UO) {
if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
return Error(UO);
LValue LVal;
if (!EvaluateLValue(UO->getSubExpr(), LVal, Info))
return false;
APValue RVal;
if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(),
UO->isIncrementOp(), &RVal))
return false;
return DerivedSuccess(RVal, UO);
}
bool VisitStmtExpr(const StmtExpr *E) {
// We will have checked the full-expressions inside the statement expression
// when they were completed, and don't need to check them again now.
if (Info.checkingForOverflow())
return Error(E);
BlockScopeRAII Scope(Info);
const CompoundStmt *CS = E->getSubStmt();
if (CS->body_empty())
return true;
for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
BE = CS->body_end();
/**/; ++BI) {
if (BI + 1 == BE) {
const Expr *FinalExpr = dyn_cast<Expr>(*BI);
if (!FinalExpr) {
Info.FFDiag((*BI)->getLocStart(),
diag::note_constexpr_stmt_expr_unsupported);
return false;
}
return this->Visit(FinalExpr);
}
APValue ReturnValue;
StmtResult Result = { ReturnValue, nullptr };
EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI);
if (ESR != ESR_Succeeded) {
// FIXME: If the statement-expression terminated due to 'return',
// 'break', or 'continue', it would be nice to propagate that to
// the outer statement evaluation rather than bailing out.
if (ESR != ESR_Failed)
Info.FFDiag((*BI)->getLocStart(),
diag::note_constexpr_stmt_expr_unsupported);
return false;
}
}
llvm_unreachable("Return from function from the loop above.");
}
/// Visit a value which is evaluated, but whose value is ignored.
void VisitIgnoredValue(const Expr *E) {
EvaluateIgnoredValue(Info, E);
}
/// Potentially visit a MemberExpr's base expression.
void VisitIgnoredBaseExpression(const Expr *E) {
// While MSVC doesn't evaluate the base expression, it does diagnose the
// presence of side-effecting behavior.
if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx))
return;
VisitIgnoredValue(E);
}
};
}
//===----------------------------------------------------------------------===//
// Common base class for lvalue and temporary evaluation.
//===----------------------------------------------------------------------===//
namespace {
template<class Derived>
class LValueExprEvaluatorBase
: public ExprEvaluatorBase<Derived> {
protected:
LValue &Result;
bool InvalidBaseOK;
typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy;
typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy;
bool Success(APValue::LValueBase B) {
Result.set(B);
return true;
}
bool evaluatePointer(const Expr *E, LValue &Result) {
return EvaluatePointer(E, Result, this->Info, InvalidBaseOK);
}
public:
LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK)
: ExprEvaluatorBaseTy(Info), Result(Result),
InvalidBaseOK(InvalidBaseOK) {}
bool Success(const APValue &V, const Expr *E) {
Result.setFrom(this->Info.Ctx, V);
return true;
}
bool VisitMemberExpr(const MemberExpr *E) {
// Handle non-static data members.
QualType BaseTy;
bool EvalOK;
if (E->isArrow()) {
EvalOK = evaluatePointer(E->getBase(), Result);
BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType();
} else if (E->getBase()->isRValue()) {
assert(E->getBase()->getType()->isRecordType());
EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info);
BaseTy = E->getBase()->getType();
} else {
EvalOK = this->Visit(E->getBase());
BaseTy = E->getBase()->getType();
}
if (!EvalOK) {
if (!InvalidBaseOK)
return false;
Result.setInvalid(E);
return true;
}
const ValueDecl *MD = E->getMemberDecl();
if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) {
assert(BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() ==
FD->getParent()->getCanonicalDecl() && "record / field mismatch");
(void)BaseTy;
if (!HandleLValueMember(this->Info, E, Result, FD))
return false;
} else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) {
if (!HandleLValueIndirectMember(this->Info, E, Result, IFD))
return false;
} else
return this->Error(E);
if (MD->getType()->isReferenceType()) {
APValue RefValue;
if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result,
RefValue))
return false;
return Success(RefValue, E);
}
return true;
}
bool VisitBinaryOperator(const BinaryOperator *E) {
switch (E->getOpcode()) {
default:
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
case BO_PtrMemD:
case BO_PtrMemI:
return HandleMemberPointerAccess(this->Info, E, Result);
}
}
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase:
if (!this->Visit(E->getSubExpr()))
return false;
// Now figure out the necessary offset to add to the base LV to get from
// the derived class to the base class.
return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(),
Result);
}
}
};
}
//===----------------------------------------------------------------------===//
// LValue Evaluation
//
// This is used for evaluating lvalues (in C and C++), xvalues (in C++11),
// function designators (in C), decl references to void objects (in C), and
// temporaries (if building with -Wno-address-of-temporary).
//
// LValue evaluation produces values comprising a base expression of one of the
// following types:
// - Declarations
// * VarDecl
// * FunctionDecl
// - Literals
// * CompoundLiteralExpr in C (and in global scope in C++)
// * StringLiteral
// * CXXTypeidExpr
// * PredefinedExpr
// * ObjCStringLiteralExpr
// * ObjCEncodeExpr
// * AddrLabelExpr
// * BlockExpr
// * CallExpr for a MakeStringConstant builtin
// - Locals and temporaries
// * MaterializeTemporaryExpr
// * Any Expr, with a CallIndex indicating the function in which the temporary
// was evaluated, for cases where the MaterializeTemporaryExpr is missing
// from the AST (FIXME).
// * A MaterializeTemporaryExpr that has static storage duration, with no
// CallIndex, for a lifetime-extended temporary.
// plus an offset in bytes.
//===----------------------------------------------------------------------===//
namespace {
class LValueExprEvaluator
: public LValueExprEvaluatorBase<LValueExprEvaluator> {
public:
LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) :
LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {}
bool VisitVarDecl(const Expr *E, const VarDecl *VD);
bool VisitUnaryPreIncDec(const UnaryOperator *UO);
bool VisitDeclRefExpr(const DeclRefExpr *E);
bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); }
bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E);
bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
bool VisitMemberExpr(const MemberExpr *E);
bool VisitStringLiteral(const StringLiteral *E) { return Success(E); }
bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); }
bool VisitCXXTypeidExpr(const CXXTypeidExpr *E);
bool VisitCXXUuidofExpr(const CXXUuidofExpr *E);
bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E);
bool VisitUnaryDeref(const UnaryOperator *E);
bool VisitUnaryReal(const UnaryOperator *E);
bool VisitUnaryImag(const UnaryOperator *E);
bool VisitUnaryPreInc(const UnaryOperator *UO) {
return VisitUnaryPreIncDec(UO);
}
bool VisitUnaryPreDec(const UnaryOperator *UO) {
return VisitUnaryPreIncDec(UO);
}
bool VisitBinAssign(const BinaryOperator *BO);
bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO);
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_LValueBitCast:
this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
if (!Visit(E->getSubExpr()))
return false;
Result.Designator.setInvalid();
return true;
case CK_BaseToDerived:
if (!Visit(E->getSubExpr()))
return false;
return HandleBaseToDerivedCast(Info, E, Result);
}
}
};
} // end anonymous namespace
/// Evaluate an expression as an lvalue. This can be legitimately called on
/// expressions which are not glvalues, in three cases:
/// * function designators in C, and
/// * "extern void" objects
/// * @selector() expressions in Objective-C
static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
bool InvalidBaseOK) {
assert(E->isGLValue() || E->getType()->isFunctionType() ||
E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E));
return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
}
bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl()))
return Success(FD);
if (const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl()))
return VisitVarDecl(E, VD);
if (const BindingDecl *BD = dyn_cast<BindingDecl>(E->getDecl()))
return Visit(BD->getBinding());
return Error(E);
}
bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
// If we are within a lambda's call operator, check whether the 'VD' referred
// to within 'E' actually represents a lambda-capture that maps to a
// data-member/field within the closure object, and if so, evaluate to the
// field or what the field refers to.
if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee)) {
if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) {
if (Info.checkingPotentialConstantExpression())
return false;
// Start with 'Result' referring to the complete closure object...
Result = *Info.CurrentCall->This;
// ... then update it to refer to the field of the closure object
// that represents the capture.
if (!HandleLValueMember(Info, E, Result, FD))
return false;
// And if the field is of reference type, update 'Result' to refer to what
// the field refers to.
if (FD->getType()->isReferenceType()) {
APValue RVal;
if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result,
RVal))
return false;
Result.setFrom(Info.Ctx, RVal);
}
return true;
}
}
CallStackFrame *Frame = nullptr;
if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) {
// Only if a local variable was declared in the function currently being
// evaluated, do we expect to be able to find its value in the current
// frame. (Otherwise it was likely declared in an enclosing context and
// could either have a valid evaluatable value (for e.g. a constexpr
// variable) or be ill-formed (and trigger an appropriate evaluation
// diagnostic)).
if (Info.CurrentCall->Callee &&
Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
Frame = Info.CurrentCall;
}
}
if (!VD->getType()->isReferenceType()) {
if (Frame) {
Result.set(VD, Frame->Index);
return true;
}
return Success(VD);
}
APValue *V;
if (!evaluateVarDeclInit(Info, E, VD, Frame, V))
return false;
if (V->isUninit()) {
if (!Info.checkingPotentialConstantExpression())
Info.FFDiag(E, diag::note_constexpr_use_uninit_reference);
return false;
}
return Success(*V, E);
}
bool LValueExprEvaluator::VisitMaterializeTemporaryExpr(
const MaterializeTemporaryExpr *E) {
// Walk through the expression to find the materialized temporary itself.
SmallVector<const Expr *, 2> CommaLHSs;
SmallVector<SubobjectAdjustment, 2> Adjustments;
const Expr *Inner = E->GetTemporaryExpr()->
skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
// If we passed any comma operators, evaluate their LHSs.
for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I)
if (!EvaluateIgnoredValue(Info, CommaLHSs[I]))
return false;
// A materialized temporary with static storage duration can appear within the
// result of a constant expression evaluation, so we need to preserve its
// value for use outside this evaluation.
APValue *Value;
if (E->getStorageDuration() == SD_Static) {
Value = Info.Ctx.getMaterializedTemporaryValue(E, true);
*Value = APValue();
Result.set(E);
} else {
Value = &Info.CurrentCall->
createTemporary(E, E->getStorageDuration() == SD_Automatic);
Result.set(E, Info.CurrentCall->Index);
}
QualType Type = Inner->getType();
// Materialize the temporary itself.
if (!EvaluateInPlace(*Value, Info, Result, Inner) ||
(E->getStorageDuration() == SD_Static &&
!CheckConstantExpression(Info, E->getExprLoc(), Type, *Value))) {
*Value = APValue();
return false;
}
// Adjust our lvalue to refer to the desired subobject.
for (unsigned I = Adjustments.size(); I != 0; /**/) {
--I;
switch (Adjustments[I].Kind) {
case SubobjectAdjustment::DerivedToBaseAdjustment:
if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath,
Type, Result))
return false;
Type = Adjustments[I].DerivedToBase.BasePath->getType();
break;
case SubobjectAdjustment::FieldAdjustment:
if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field))
return false;
Type = Adjustments[I].Field->getType();
break;
case SubobjectAdjustment::MemberPointerAdjustment:
if (!HandleMemberPointerAccess(this->Info, Type, Result,
Adjustments[I].Ptr.RHS))
return false;
Type = Adjustments[I].Ptr.MPT->getPointeeType();
break;
}
}
return true;
}
bool
LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&
"lvalue compound literal in c++?");
// Defer visiting the literal until the lvalue-to-rvalue conversion. We can
// only see this when folding in C, so there's no standard to follow here.
return Success(E);
}
bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
if (!E->isPotentiallyEvaluated())
return Success(E);
Info.FFDiag(E, diag::note_constexpr_typeid_polymorphic)
<< E->getExprOperand()->getType()
<< E->getExprOperand()->getSourceRange();
return false;
}
bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) {
return Success(E);
}
bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
// Handle static data members.
if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) {
VisitIgnoredBaseExpression(E->getBase());
return VisitVarDecl(E, VD);
}
// Handle static member functions.
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) {
if (MD->isStatic()) {
VisitIgnoredBaseExpression(E->getBase());
return Success(MD);
}
}
// Handle non-static data members.
return LValueExprEvaluatorBaseTy::VisitMemberExpr(E);
}
bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
// FIXME: Deal with vectors as array subscript bases.
if (E->getBase()->getType()->isVectorType())
return Error(E);
bool Success = true;
if (!evaluatePointer(E->getBase(), Result)) {
if (!Info.noteFailure())
return false;
Success = false;
}
APSInt Index;
if (!EvaluateInteger(E->getIdx(), Index, Info))
return false;
return Success &&
HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index);
}
bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) {
return evaluatePointer(E->getSubExpr(), Result);
}
bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
if (!Visit(E->getSubExpr()))
return false;
// __real is a no-op on scalar lvalues.
if (E->getSubExpr()->getType()->isAnyComplexType())
HandleLValueComplexElement(Info, E, Result, E->getType(), false);
return true;
}
bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
assert(E->getSubExpr()->getType()->isAnyComplexType() &&
"lvalue __imag__ on scalar?");
if (!Visit(E->getSubExpr()))
return false;
HandleLValueComplexElement(Info, E, Result, E->getType(), true);
return true;
}
bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) {
if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
return Error(UO);
if (!this->Visit(UO->getSubExpr()))
return false;
return handleIncDec(
this->Info, UO, Result, UO->getSubExpr()->getType(),
UO->isIncrementOp(), nullptr);
}
bool LValueExprEvaluator::VisitCompoundAssignOperator(
const CompoundAssignOperator *CAO) {
if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
return Error(CAO);
APValue RHS;
// The overall lvalue result is the result of evaluating the LHS.
if (!this->Visit(CAO->getLHS())) {
if (Info.noteFailure())
Evaluate(RHS, this->Info, CAO->getRHS());
return false;
}
if (!Evaluate(RHS, this->Info, CAO->getRHS()))
return false;
return handleCompoundAssignment(
this->Info, CAO,
Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(),
CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS);
}
bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) {
if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
return Error(E);
APValue NewVal;
if (!this->Visit(E->getLHS())) {
if (Info.noteFailure())
Evaluate(NewVal, this->Info, E->getRHS());
return false;
}
if (!Evaluate(NewVal, this->Info, E->getRHS()))
return false;
return handleAssignment(this->Info, E, Result, E->getLHS()->getType(),
NewVal);
}
//===----------------------------------------------------------------------===//
// Pointer Evaluation
//===----------------------------------------------------------------------===//
/// \brief Attempts to compute the number of bytes available at the pointer
/// returned by a function with the alloc_size attribute. Returns true if we
/// were successful. Places an unsigned number into `Result`.
///
/// This expects the given CallExpr to be a call to a function with an
/// alloc_size attribute.
static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
const CallExpr *Call,
llvm::APInt &Result) {
const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call);
// alloc_size args are 1-indexed, 0 means not present.
assert(AllocSize && AllocSize->getElemSizeParam() != 0);
unsigned SizeArgNo = AllocSize->getElemSizeParam() - 1;
unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType());
if (Call->getNumArgs() <= SizeArgNo)
return false;
auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) {
if (!E->EvaluateAsInt(Into, Ctx, Expr::SE_AllowSideEffects))
return false;
if (Into.isNegative() || !Into.isIntN(BitsInSizeT))
return false;
Into = Into.zextOrSelf(BitsInSizeT);
return true;
};
APSInt SizeOfElem;
if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem))
return false;
if (!AllocSize->getNumElemsParam()) {
Result = std::move(SizeOfElem);
return true;
}
APSInt NumberOfElems;
// Argument numbers start at 1
unsigned NumArgNo = AllocSize->getNumElemsParam() - 1;
if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems))
return false;
bool Overflow;
llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow);
if (Overflow)
return false;
Result = std::move(BytesAvailable);
return true;
}
/// \brief Convenience function. LVal's base must be a call to an alloc_size
/// function.
static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
const LValue &LVal,
llvm::APInt &Result) {
assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
"Can't get the size of a non alloc_size function");
const auto *Base = LVal.getLValueBase().get<const Expr *>();
const CallExpr *CE = tryUnwrapAllocSizeCall(Base);
return getBytesReturnedByAllocSizeCall(Ctx, CE, Result);
}
/// \brief Attempts to evaluate the given LValueBase as the result of a call to
/// a function with the alloc_size attribute. If it was possible to do so, this
/// function will return true, make Result's Base point to said function call,
/// and mark Result's Base as invalid.
static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base,
LValue &Result) {
if (Base.isNull())
return false;
// Because we do no form of static analysis, we only support const variables.
//
// Additionally, we can't support parameters, nor can we support static
// variables (in the latter case, use-before-assign isn't UB; in the former,
// we have no clue what they'll be assigned to).
const auto *VD =
dyn_cast_or_null<VarDecl>(Base.dyn_cast<const ValueDecl *>());
if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified())
return false;
const Expr *Init = VD->getAnyInitializer();
if (!Init)
return false;
const Expr *E = Init->IgnoreParens();
if (!tryUnwrapAllocSizeCall(E))
return false;
// Store E instead of E unwrapped so that the type of the LValue's base is
// what the user wanted.
Result.setInvalid(E);
QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType();
Result.addUnsizedArray(Info, Pointee);
return true;
}
namespace {
class PointerExprEvaluator
: public ExprEvaluatorBase<PointerExprEvaluator> {
LValue &Result;
bool InvalidBaseOK;
bool Success(const Expr *E) {
Result.set(E);
return true;
}
bool evaluateLValue(const Expr *E, LValue &Result) {
return EvaluateLValue(E, Result, Info, InvalidBaseOK);
}
bool evaluatePointer(const Expr *E, LValue &Result) {
return EvaluatePointer(E, Result, Info, InvalidBaseOK);
}
bool visitNonBuiltinCallExpr(const CallExpr *E);
public:
PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK)
: ExprEvaluatorBaseTy(info), Result(Result),
InvalidBaseOK(InvalidBaseOK) {}
bool Success(const APValue &V, const Expr *E) {
Result.setFrom(Info.Ctx, V);
return true;
}
bool ZeroInitialization(const Expr *E) {
auto Offset = Info.Ctx.getTargetNullPointerValue(E->getType());
Result.set((Expr*)nullptr, 0, false, true, Offset);
return true;
}
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitCastExpr(const CastExpr* E);
bool VisitUnaryAddrOf(const UnaryOperator *E);
bool VisitObjCStringLiteral(const ObjCStringLiteral *E)
{ return Success(E); }
bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
if (Info.noteFailure())
EvaluateIgnoredValue(Info, E->getSubExpr());
return Error(E);
}
bool VisitAddrLabelExpr(const AddrLabelExpr *E)
{ return Success(E); }
bool VisitCallExpr(const CallExpr *E);
bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
bool VisitBlockExpr(const BlockExpr *E) {
if (!E->getBlockDecl()->hasCaptures())
return Success(E);
return Error(E);
}
bool VisitCXXThisExpr(const CXXThisExpr *E) {
// Can't look at 'this' when checking a potential constant expression.
if (Info.checkingPotentialConstantExpression())
return false;
if (!Info.CurrentCall->This) {
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit();
else
Info.FFDiag(E);
return false;
}
Result = *Info.CurrentCall->This;
// If we are inside a lambda's call operator, the 'this' expression refers
// to the enclosing '*this' object (either by value or reference) which is
// either copied into the closure object's field that represents the '*this'
// or refers to '*this'.
if (isLambdaCallOperator(Info.CurrentCall->Callee)) {
// Update 'Result' to refer to the data member/field of the closure object
// that represents the '*this' capture.
if (!HandleLValueMember(Info, E, Result,
Info.CurrentCall->LambdaThisCaptureField))
return false;
// If we captured '*this' by reference, replace the field with its referent.
if (Info.CurrentCall->LambdaThisCaptureField->getType()
->isPointerType()) {
APValue RVal;
if (!handleLValueToRValueConversion(Info, E, E->getType(), Result,
RVal))
return false;
Result.setFrom(Info.Ctx, RVal);
}
}
return true;
}
// FIXME: Missing: @protocol, @selector
};
} // end anonymous namespace
static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info,
bool InvalidBaseOK) {
assert(E->isRValue() && E->getType()->hasPointerRepresentation());
return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
}
bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->getOpcode() != BO_Add &&
E->getOpcode() != BO_Sub)
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
const Expr *PExp = E->getLHS();
const Expr *IExp = E->getRHS();
if (IExp->getType()->isPointerType())
std::swap(PExp, IExp);
bool EvalPtrOK = evaluatePointer(PExp, Result);
if (!EvalPtrOK && !Info.noteFailure())
return false;
llvm::APSInt Offset;
if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK)
return false;
if (E->getOpcode() == BO_Sub)
negateAsSigned(Offset);
QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType();
return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset);
}
bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
return evaluateLValue(E->getSubExpr(), Result);
}
bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
const Expr* SubExpr = E->getSubExpr();
switch (E->getCastKind()) {
default:
break;
case CK_BitCast:
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:
case CK_AddressSpaceConversion:
if (!Visit(SubExpr))
return false;
// Bitcasts to cv void* are static_casts, not reinterpret_casts, so are
// permitted in constant expressions in C++11. Bitcasts from cv void* are
// also static_casts, but we disallow them as a resolution to DR1312.
if (!E->getType()->isVoidPointerType()) {
Result.Designator.setInvalid();
if (SubExpr->getType()->isVoidPointerType())
CCEDiag(E, diag::note_constexpr_invalid_cast)
<< 3 << SubExpr->getType();
else
CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
}
if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr)
ZeroInitialization(E);
return true;
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase:
if (!evaluatePointer(E->getSubExpr(), Result))
return false;
if (!Result.Base && Result.Offset.isZero())
return true;
// Now figure out the necessary offset to add to the base LV to get from
// the derived class to the base class.
return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()->
castAs<PointerType>()->getPointeeType(),
Result);
case CK_BaseToDerived:
if (!Visit(E->getSubExpr()))
return false;
if (!Result.Base && Result.Offset.isZero())
return true;
return HandleBaseToDerivedCast(Info, E, Result);
case CK_NullToPointer:
VisitIgnoredValue(E->getSubExpr());
return ZeroInitialization(E);
case CK_IntegralToPointer: {
CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
APValue Value;
if (!EvaluateIntegerOrLValue(SubExpr, Value, Info))
break;
if (Value.isInt()) {
unsigned Size = Info.Ctx.getTypeSize(E->getType());
uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue();
Result.Base = (Expr*)nullptr;
Result.InvalidBase = false;
Result.Offset = CharUnits::fromQuantity(N);
Result.CallIndex = 0;
Result.Designator.setInvalid();
Result.IsNullPtr = false;
return true;
} else {
// Cast is of an lvalue, no need to change value.
Result.setFrom(Info.Ctx, Value);
return true;
}
}
case CK_ArrayToPointerDecay:
if (SubExpr->isGLValue()) {
if (!evaluateLValue(SubExpr, Result))
return false;
} else {
Result.set(SubExpr, Info.CurrentCall->Index);
if (!EvaluateInPlace(Info.CurrentCall->createTemporary(SubExpr, false),
Info, Result, SubExpr))
return false;
}
// The result is a pointer to the first element of the array.
if (const ConstantArrayType *CAT
= Info.Ctx.getAsConstantArrayType(SubExpr->getType()))
Result.addArray(Info, E, CAT);
else
Result.Designator.setInvalid();
return true;
case CK_FunctionToPointerDecay:
return evaluateLValue(SubExpr, Result);
case CK_LValueToRValue: {
LValue LVal;
if (!evaluateLValue(E->getSubExpr(), LVal))
return false;
APValue RVal;
// Note, we use the subexpression's type in order to retain cv-qualifiers.
if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
LVal, RVal))
return InvalidBaseOK &&
evaluateLValueAsAllocSize(Info, LVal.Base, Result);
return Success(RVal, E);
}
}
return ExprEvaluatorBaseTy::VisitCastExpr(E);
}
static CharUnits GetAlignOfType(EvalInfo &Info, QualType T) {
// C++ [expr.alignof]p3:
// When alignof is applied to a reference type, the result is the
// alignment of the referenced type.
if (const ReferenceType *Ref = T->getAs<ReferenceType>())
T = Ref->getPointeeType();
// __alignof is defined to return the preferred alignment.
if (T.getQualifiers().hasUnaligned())
return CharUnits::One();
return Info.Ctx.toCharUnitsFromBits(
Info.Ctx.getPreferredTypeAlign(T.getTypePtr()));
}
static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E) {
E = E->IgnoreParens();
// The kinds of expressions that we have special-case logic here for
// should be kept up to date with the special checks for those
// expressions in Sema.
// alignof decl is always accepted, even if it doesn't make sense: we default
// to 1 in those cases.
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
return Info.Ctx.getDeclAlign(DRE->getDecl(),
/*RefAsPointee*/true);
if (const MemberExpr *ME = dyn_cast<MemberExpr>(E))
return Info.Ctx.getDeclAlign(ME->getMemberDecl(),
/*RefAsPointee*/true);
return GetAlignOfType(Info, E->getType());
}
// To be clear: this happily visits unsupported builtins. Better name welcomed.
bool PointerExprEvaluator::visitNonBuiltinCallExpr(const CallExpr *E) {
if (ExprEvaluatorBaseTy::VisitCallExpr(E))
return true;
if (!(InvalidBaseOK && getAllocSizeAttr(E)))
return false;
Result.setInvalid(E);
QualType PointeeTy = E->getType()->castAs<PointerType>()->getPointeeType();
Result.addUnsizedArray(Info, PointeeTy);
return true;
}
bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) {
if (IsStringLiteralCall(E))
return Success(E);
if (unsigned BuiltinOp = E->getBuiltinCallee())
return VisitBuiltinCallExpr(E, BuiltinOp);
return visitNonBuiltinCallExpr(E);
}
bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
unsigned BuiltinOp) {
switch (BuiltinOp) {
case Builtin::BI__builtin_addressof:
return evaluateLValue(E->getArg(0), Result);
case Builtin::BI__builtin_assume_aligned: {
// We need to be very careful here because: if the pointer does not have the
// asserted alignment, then the behavior is undefined, and undefined
// behavior is non-constant.
if (!evaluatePointer(E->getArg(0), Result))
return false;
LValue OffsetResult(Result);
APSInt Alignment;
if (!EvaluateInteger(E->getArg(1), Alignment, Info))
return false;
CharUnits Align = CharUnits::fromQuantity(Alignment.getZExtValue());
if (E->getNumArgs() > 2) {
APSInt Offset;
if (!EvaluateInteger(E->getArg(2), Offset, Info))
return false;
int64_t AdditionalOffset = -Offset.getZExtValue();
OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset);
}
// If there is a base object, then it must have the correct alignment.
if (OffsetResult.Base) {
CharUnits BaseAlignment;
if (const ValueDecl *VD =
OffsetResult.Base.dyn_cast<const ValueDecl*>()) {
BaseAlignment = Info.Ctx.getDeclAlign(VD);
} else {
BaseAlignment =
GetAlignOfExpr(Info, OffsetResult.Base.get<const Expr*>());
}
if (BaseAlignment < Align) {
Result.Designator.setInvalid();
// FIXME: Add support to Diagnostic for long / long long.
CCEDiag(E->getArg(0),
diag::note_constexpr_baa_insufficient_alignment) << 0
<< (unsigned)BaseAlignment.getQuantity()
<< (unsigned)Align.getQuantity();
return false;
}
}
// The offset must also have the correct alignment.
if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) {
Result.Designator.setInvalid();
(OffsetResult.Base
? CCEDiag(E->getArg(0),
diag::note_constexpr_baa_insufficient_alignment) << 1
: CCEDiag(E->getArg(0),
diag::note_constexpr_baa_value_insufficient_alignment))
<< (int)OffsetResult.Offset.getQuantity()
<< (unsigned)Align.getQuantity();
return false;
}
return true;
}
case Builtin::BIstrchr:
case Builtin::BIwcschr:
case Builtin::BImemchr:
case Builtin::BIwmemchr:
if (Info.getLangOpts().CPlusPlus11)
Info.CCEDiag(E, diag::note_constexpr_invalid_function)
<< /*isConstexpr*/0 << /*isConstructor*/0
<< (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
else
Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
// Fall through.
case Builtin::BI__builtin_strchr:
case Builtin::BI__builtin_wcschr:
case Builtin::BI__builtin_memchr:
case Builtin::BI__builtin_char_memchr:
case Builtin::BI__builtin_wmemchr: {
if (!Visit(E->getArg(0)))
return false;
APSInt Desired;
if (!EvaluateInteger(E->getArg(1), Desired, Info))
return false;
uint64_t MaxLength = uint64_t(-1);
if (BuiltinOp != Builtin::BIstrchr &&
BuiltinOp != Builtin::BIwcschr &&
BuiltinOp != Builtin::BI__builtin_strchr &&
BuiltinOp != Builtin::BI__builtin_wcschr) {
APSInt N;
if (!EvaluateInteger(E->getArg(2), N, Info))
return false;
MaxLength = N.getExtValue();
}
QualType CharTy = E->getArg(0)->getType()->getPointeeType();
// Figure out what value we're actually looking for (after converting to
// the corresponding unsigned type if necessary).
uint64_t DesiredVal;
bool StopAtNull = false;
switch (BuiltinOp) {
case Builtin::BIstrchr:
case Builtin::BI__builtin_strchr:
// strchr compares directly to the passed integer, and therefore
// always fails if given an int that is not a char.
if (!APSInt::isSameValue(HandleIntToIntCast(Info, E, CharTy,
E->getArg(1)->getType(),
Desired),
Desired))
return ZeroInitialization(E);
StopAtNull = true;
// Fall through.
case Builtin::BImemchr:
case Builtin::BI__builtin_memchr:
case Builtin::BI__builtin_char_memchr:
// memchr compares by converting both sides to unsigned char. That's also
// correct for strchr if we get this far (to cope with plain char being
// unsigned in the strchr case).
DesiredVal = Desired.trunc(Info.Ctx.getCharWidth()).getZExtValue();
break;
case Builtin::BIwcschr:
case Builtin::BI__builtin_wcschr:
StopAtNull = true;
// Fall through.
case Builtin::BIwmemchr:
case Builtin::BI__builtin_wmemchr:
// wcschr and wmemchr are given a wchar_t to look for. Just use it.
DesiredVal = Desired.getZExtValue();
break;
}
for (; MaxLength; --MaxLength) {
APValue Char;
if (!handleLValueToRValueConversion(Info, E, CharTy, Result, Char) ||
!Char.isInt())
return false;
if (Char.getInt().getZExtValue() == DesiredVal)
return true;
if (StopAtNull && !Char.getInt())
break;
if (!HandleLValueArrayAdjustment(Info, E, Result, CharTy, 1))
return false;
}
// Not found: return nullptr.
return ZeroInitialization(E);
}
default:
return visitNonBuiltinCallExpr(E);
}
}
//===----------------------------------------------------------------------===//
// Member Pointer Evaluation
//===----------------------------------------------------------------------===//
namespace {
class MemberPointerExprEvaluator
: public ExprEvaluatorBase<MemberPointerExprEvaluator> {
MemberPtr &Result;
bool Success(const ValueDecl *D) {
Result = MemberPtr(D);
return true;
}
public:
MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result)
: ExprEvaluatorBaseTy(Info), Result(Result) {}
bool Success(const APValue &V, const Expr *E) {
Result.setFrom(V);
return true;
}
bool ZeroInitialization(const Expr *E) {
return Success((const ValueDecl*)nullptr);
}
bool VisitCastExpr(const CastExpr *E);
bool VisitUnaryAddrOf(const UnaryOperator *E);
};
} // end anonymous namespace
static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isMemberPointerType());
return MemberPointerExprEvaluator(Info, Result).Visit(E);
}
bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_NullToMemberPointer:
VisitIgnoredValue(E->getSubExpr());
return ZeroInitialization(E);
case CK_BaseToDerivedMemberPointer: {
if (!Visit(E->getSubExpr()))
return false;
if (E->path_empty())
return true;
// Base-to-derived member pointer casts store the path in derived-to-base
// order, so iterate backwards. The CXXBaseSpecifier also provides us with
// the wrong end of the derived->base arc, so stagger the path by one class.
typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter;
for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin());
PathI != PathE; ++PathI) {
assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl();
if (!Result.castToDerived(Derived))
return Error(E);
}
const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass();
if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl()))
return Error(E);
return true;
}
case CK_DerivedToBaseMemberPointer:
if (!Visit(E->getSubExpr()))
return false;
for (CastExpr::path_const_iterator PathI = E->path_begin(),
PathE = E->path_end(); PathI != PathE; ++PathI) {
assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
if (!Result.castToBase(Base))
return Error(E);
}
return true;
}
}
bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
// C++11 [expr.unary.op]p3 has very strict rules on how the address of a
// member can be formed.
return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl());
}
//===----------------------------------------------------------------------===//
// Record Evaluation
//===----------------------------------------------------------------------===//
namespace {
class RecordExprEvaluator
: public ExprEvaluatorBase<RecordExprEvaluator> {
const LValue &This;
APValue &Result;
public:
RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result)
: ExprEvaluatorBaseTy(info), This(This), Result(Result) {}
bool Success(const APValue &V, const Expr *E) {
Result = V;
return true;
}
bool ZeroInitialization(const Expr *E) {
return ZeroInitialization(E, E->getType());
}
bool ZeroInitialization(const Expr *E, QualType T);
bool VisitCallExpr(const CallExpr *E) {
return handleCallExpr(E, Result, &This);
}
bool VisitCastExpr(const CastExpr *E);
bool VisitInitListExpr(const InitListExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
return VisitCXXConstructExpr(E, E->getType());
}
bool VisitLambdaExpr(const LambdaExpr *E);
bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T);
bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E);
};
}
/// Perform zero-initialization on an object of non-union class type.
/// C++11 [dcl.init]p5:
/// To zero-initialize an object or reference of type T means:
/// [...]
/// -- if T is a (possibly cv-qualified) non-union class type,
/// each non-static data member and each base-class subobject is
/// zero-initialized
static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E,
const RecordDecl *RD,
const LValue &This, APValue &Result) {
assert(!RD->isUnion() && "Expected non-union class type");
const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD);
Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0,
std::distance(RD->field_begin(), RD->field_end()));
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
if (CD) {
unsigned Index = 0;
for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(),
End = CD->bases_end(); I != End; ++I, ++Index) {
const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl();
LValue Subobject = This;
if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout))
return false;
if (!HandleClassZeroInitialization(Info, E, Base, Subobject,
Result.getStructBase(Index)))
return false;
}
}
for (const auto *I : RD->fields()) {
// -- if T is a reference type, no initialization is performed.
if (I->getType()->isReferenceType())
continue;
LValue Subobject = This;
if (!HandleLValueMember(Info, E, Subobject, I, &Layout))
return false;
ImplicitValueInitExpr VIE(I->getType());
if (!EvaluateInPlace(
Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE))
return false;
}
return true;
}
bool RecordExprEvaluator::ZeroInitialization(const Expr *E, QualType T) {
const RecordDecl *RD = T->castAs<RecordType>()->getDecl();
if (RD->isInvalidDecl()) return false;
if (RD->isUnion()) {
// C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the
// object's first non-static named data member is zero-initialized
RecordDecl::field_iterator I = RD->field_begin();
if (I == RD->field_end()) {
Result = APValue((const FieldDecl*)nullptr);
return true;
}
LValue Subobject = This;
if (!HandleLValueMember(Info, E, Subobject, *I))
return false;
Result = APValue(*I);
ImplicitValueInitExpr VIE(I->getType());
return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE);
}
if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) {
Info.FFDiag(E, diag::note_constexpr_virtual_base) << RD;
return false;
}
return HandleClassZeroInitialization(Info, E, RD, This, Result);
}
bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_ConstructorConversion:
return Visit(E->getSubExpr());
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase: {
APValue DerivedObject;
if (!Evaluate(DerivedObject, Info, E->getSubExpr()))
return false;
if (!DerivedObject.isStruct())
return Error(E->getSubExpr());
// Derived-to-base rvalue conversion: just slice off the derived part.
APValue *Value = &DerivedObject;
const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl();
for (CastExpr::path_const_iterator PathI = E->path_begin(),
PathE = E->path_end(); PathI != PathE; ++PathI) {
assert(!(*PathI)->isVirtual() && "record rvalue with virtual base");
const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
Value = &Value->getStructBase(getBaseIndex(RD, Base));
RD = Base;
}
Result = *Value;
return true;
}
}
}
bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
if (E->isTransparent())
return Visit(E->getInit(0));
const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl();
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
if (RD->isUnion()) {
const FieldDecl *Field = E->getInitializedFieldInUnion();
Result = APValue(Field);
if (!Field)
return true;
// If the initializer list for a union does not contain any elements, the
// first element of the union is value-initialized.
// FIXME: The element should be initialized from an initializer list.
// Is this difference ever observable for initializer lists which
// we don't build?
ImplicitValueInitExpr VIE(Field->getType());
const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE;
LValue Subobject = This;
if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout))
return false;
// Temporarily override This, in case there's a CXXDefaultInitExpr in here.
ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
isa<CXXDefaultInitExpr>(InitExpr));
return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr);
}
auto *CXXRD = dyn_cast<CXXRecordDecl>(RD);
if (Result.isUninit())
Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0,
std::distance(RD->field_begin(), RD->field_end()));
unsigned ElementNo = 0;
bool Success = true;
// Initialize base classes.
if (CXXRD) {
for (const auto &Base : CXXRD->bases()) {
assert(ElementNo < E->getNumInits() && "missing init for base class");
const Expr *Init = E->getInit(ElementNo);
LValue Subobject = This;
if (!HandleLValueBase(Info, Init, Subobject, CXXRD, &Base))
return false;
APValue &FieldVal = Result.getStructBase(ElementNo);
if (!EvaluateInPlace(FieldVal, Info, Subobject, Init)) {
if (!Info.noteFailure())
return false;
Success = false;
}
++ElementNo;
}
}
// Initialize members.
for (const auto *Field : RD->fields()) {
// Anonymous bit-fields are not considered members of the class for
// purposes of aggregate initialization.
if (Field->isUnnamedBitfield())
continue;
LValue Subobject = This;
bool HaveInit = ElementNo < E->getNumInits();
// FIXME: Diagnostics here should point to the end of the initializer
// list, not the start.
if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E,
Subobject, Field, &Layout))
return false;
// Perform an implicit value-initialization for members beyond the end of
// the initializer list.
ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType());
const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE;
if (Init->isValueDependent()) {
Success = false;
continue;
}
// Temporarily override This, in case there's a CXXDefaultInitExpr in here.
ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
isa<CXXDefaultInitExpr>(Init));
APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) ||
(Field->isBitField() && !truncateBitfieldValue(Info, Init,
FieldVal, Field))) {
if (!Info.noteFailure())
return false;
Success = false;
}
}
return Success;
}
bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
QualType T) {
// Note that E's type is not necessarily the type of our class here; we might
// be initializing an array element instead.
const CXXConstructorDecl *FD = E->getConstructor();
if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false;
bool ZeroInit = E->requiresZeroInitialization();
if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) {
// If we've already performed zero-initialization, we're already done.
if (!Result.isUninit())
return true;
// We can get here in two different ways:
// 1) We're performing value-initialization, and should zero-initialize
// the object, or
// 2) We're performing default-initialization of an object with a trivial
// constexpr default constructor, in which case we should start the
// lifetimes of all the base subobjects (there can be no data member
// subobjects in this case) per [basic.life]p1.
// Either way, ZeroInitialization is appropriate.
return ZeroInitialization(E, T);
}
const FunctionDecl *Definition = nullptr;
auto Body = FD->getBody(Definition);
if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
return false;
// Avoid materializing a temporary for an elidable copy/move constructor.
if (E->isElidable() && !ZeroInit)
if (const MaterializeTemporaryExpr *ME
= dyn_cast<MaterializeTemporaryExpr>(E->getArg(0)))
return Visit(ME->GetTemporaryExpr());
if (ZeroInit && !ZeroInitialization(E, T))
return false;
auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
return HandleConstructorCall(E, This, Args,
cast<CXXConstructorDecl>(Definition), Info,
Result);
}
bool RecordExprEvaluator::VisitCXXInheritedCtorInitExpr(
const CXXInheritedCtorInitExpr *E) {
if (!Info.CurrentCall) {
assert(Info.checkingPotentialConstantExpression());
return false;
}
const CXXConstructorDecl *FD = E->getConstructor();
if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl())
return false;
const FunctionDecl *Definition = nullptr;
auto Body = FD->getBody(Definition);
if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
return false;
return HandleConstructorCall(E, This, Info.CurrentCall->Arguments,
cast<CXXConstructorDecl>(Definition), Info,
Result);
}
bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
const CXXStdInitializerListExpr *E) {
const ConstantArrayType *ArrayType =
Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
LValue Array;
if (!EvaluateLValue(E->getSubExpr(), Array, Info))
return false;
// Get a pointer to the first element of the array.
Array.addArray(Info, E, ArrayType);
// FIXME: Perform the checks on the field types in SemaInit.
RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
RecordDecl::field_iterator Field = Record->field_begin();
if (Field == Record->field_end())
return Error(E);
// Start pointer.
if (!Field->getType()->isPointerType() ||
!Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
ArrayType->getElementType()))
return Error(E);
// FIXME: What if the initializer_list type has base classes, etc?
Result = APValue(APValue::UninitStruct(), 0, 2);
Array.moveInto(Result.getStructField(0));
if (++Field == Record->field_end())
return Error(E);
if (Field->getType()->isPointerType() &&
Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
ArrayType->getElementType())) {
// End pointer.
if (!HandleLValueArrayAdjustment(Info, E, Array,
ArrayType->getElementType(),
ArrayType->getSize().getZExtValue()))
return false;
Array.moveInto(Result.getStructField(1));
} else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType()))
// Length.
Result.getStructField(1) = APValue(APSInt(ArrayType->getSize()));
else
return Error(E);
if (++Field != Record->field_end())
return Error(E);
return true;
}
bool RecordExprEvaluator::VisitLambdaExpr(const LambdaExpr *E) {
const CXXRecordDecl *ClosureClass = E->getLambdaClass();
if (ClosureClass->isInvalidDecl()) return false;
if (Info.checkingPotentialConstantExpression()) return true;
const size_t NumFields =
std::distance(ClosureClass->field_begin(), ClosureClass->field_end());
assert(NumFields == (size_t)std::distance(E->capture_init_begin(),
E->capture_init_end()) &&
"The number of lambda capture initializers should equal the number of "
"fields within the closure type");
Result = APValue(APValue::UninitStruct(), /*NumBases*/0, NumFields);
// Iterate through all the lambda's closure object's fields and initialize
// them.
auto *CaptureInitIt = E->capture_init_begin();
const LambdaCapture *CaptureIt = ClosureClass->captures_begin();
bool Success = true;
for (const auto *Field : ClosureClass->fields()) {
assert(CaptureInitIt != E->capture_init_end());
// Get the initializer for this field
Expr *const CurFieldInit = *CaptureInitIt++;
// If there is no initializer, either this is a VLA or an error has
// occurred.
if (!CurFieldInit)
return Error(E);
APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
if (!EvaluateInPlace(FieldVal, Info, This, CurFieldInit)) {
if (!Info.keepEvaluatingAfterFailure())
return false;
Success = false;
}
++CaptureIt;
}
return Success;
}
static bool EvaluateRecord(const Expr *E, const LValue &This,
APValue &Result, EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isRecordType() &&
"can't evaluate expression as a record rvalue");
return RecordExprEvaluator(Info, This, Result).Visit(E);
}
//===----------------------------------------------------------------------===//
// Temporary Evaluation
//
// Temporaries are represented in the AST as rvalues, but generally behave like
// lvalues. The full-object of which the temporary is a subobject is implicitly
// materialized so that a reference can bind to it.
//===----------------------------------------------------------------------===//
namespace {
class TemporaryExprEvaluator
: public LValueExprEvaluatorBase<TemporaryExprEvaluator> {
public:
TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) :
LValueExprEvaluatorBaseTy(Info, Result, false) {}
/// Visit an expression which constructs the value of this temporary.
bool VisitConstructExpr(const Expr *E) {
Result.set(E, Info.CurrentCall->Index);
return EvaluateInPlace(Info.CurrentCall->createTemporary(E, false),
Info, Result, E);
}
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_ConstructorConversion:
return VisitConstructExpr(E->getSubExpr());
}
}
bool VisitInitListExpr(const InitListExpr *E) {
return VisitConstructExpr(E);
}
bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
return VisitConstructExpr(E);
}
bool VisitCallExpr(const CallExpr *E) {
return VisitConstructExpr(E);
}
bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) {
return VisitConstructExpr(E);
}
bool VisitLambdaExpr(const LambdaExpr *E) {
return VisitConstructExpr(E);
}
};
} // end anonymous namespace
/// Evaluate an expression of record type as a temporary.
static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isRecordType());
return TemporaryExprEvaluator(Info, Result).Visit(E);
}
//===----------------------------------------------------------------------===//
// Vector Evaluation
//===----------------------------------------------------------------------===//
namespace {
class VectorExprEvaluator
: public ExprEvaluatorBase<VectorExprEvaluator> {
APValue &Result;
public:
VectorExprEvaluator(EvalInfo &info, APValue &Result)
: ExprEvaluatorBaseTy(info), Result(Result) {}
bool Success(ArrayRef<APValue> V, const Expr *E) {
assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements());
// FIXME: remove this APValue copy.
Result = APValue(V.data(), V.size());
return true;
}
bool Success(const APValue &V, const Expr *E) {
assert(V.isVector());
Result = V;
return true;
}
bool ZeroInitialization(const Expr *E);
bool VisitUnaryReal(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
bool VisitCastExpr(const CastExpr* E);
bool VisitInitListExpr(const InitListExpr *E);
bool VisitUnaryImag(const UnaryOperator *E);
// FIXME: Missing: unary -, unary ~, binary add/sub/mul/div,
// binary comparisons, binary and/or/xor,
// shufflevector, ExtVectorElementExpr
};
} // end anonymous namespace
static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue");
return VectorExprEvaluator(Info, Result).Visit(E);
}
bool VectorExprEvaluator::VisitCastExpr(const CastExpr *E) {
const VectorType *VTy = E->getType()->castAs<VectorType>();
unsigned NElts = VTy->getNumElements();
const Expr *SE = E->getSubExpr();
QualType SETy = SE->getType();
switch (E->getCastKind()) {
case CK_VectorSplat: {
APValue Val = APValue();
if (SETy->isIntegerType()) {
APSInt IntResult;
if (!EvaluateInteger(SE, IntResult, Info))
return false;
Val = APValue(std::move(IntResult));
} else if (SETy->isRealFloatingType()) {
APFloat FloatResult(0.0);
if (!EvaluateFloat(SE, FloatResult, Info))
return false;
Val = APValue(std::move(FloatResult));
} else {
return Error(E);
}
// Splat and create vector APValue.
SmallVector<APValue, 4> Elts(NElts, Val);
return Success(Elts, E);
}
case CK_BitCast: {
// Evaluate the operand into an APInt we can extract from.
llvm::APInt SValInt;
if (!EvalAndBitcastToAPInt(Info, SE, SValInt))
return false;
// Extract the elements
QualType EltTy = VTy->getElementType();
unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
SmallVector<APValue, 4> Elts;
if (EltTy->isRealFloatingType()) {
const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy);
unsigned FloatEltSize = EltSize;
if (&Sem == &APFloat::x87DoubleExtended())
FloatEltSize = 80;
for (unsigned i = 0; i < NElts; i++) {
llvm::APInt Elt;
if (BigEndian)
Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize);
else
Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize);
Elts.push_back(APValue(APFloat(Sem, Elt)));
}
} else if (EltTy->isIntegerType()) {
for (unsigned i = 0; i < NElts; i++) {
llvm::APInt Elt;
if (BigEndian)
Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize);
else
Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize);
Elts.push_back(APValue(APSInt(Elt, EltTy->isSignedIntegerType())));
}
} else {
return Error(E);
}
return Success(Elts, E);
}
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
}
}
bool
VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
const VectorType *VT = E->getType()->castAs<VectorType>();
unsigned NumInits = E->getNumInits();
unsigned NumElements = VT->getNumElements();
QualType EltTy = VT->getElementType();
SmallVector<APValue, 4> Elements;
// The number of initializers can be less than the number of
// vector elements. For OpenCL, this can be due to nested vector
// initialization. For GCC compatibility, missing trailing elements
// should be initialized with zeroes.
unsigned CountInits = 0, CountElts = 0;
while (CountElts < NumElements) {
// Handle nested vector initialization.
if (CountInits < NumInits
&& E->getInit(CountInits)->getType()->isVectorType()) {
APValue v;
if (!EvaluateVector(E->getInit(CountInits), v, Info))
return Error(E);
unsigned vlen = v.getVectorLength();
for (unsigned j = 0; j < vlen; j++)
Elements.push_back(v.getVectorElt(j));
CountElts += vlen;
} else if (EltTy->isIntegerType()) {
llvm::APSInt sInt(32);
if (CountInits < NumInits) {
if (!EvaluateInteger(E->getInit(CountInits), sInt, Info))
return false;
} else // trailing integer zero.
sInt = Info.Ctx.MakeIntValue(0, EltTy);
Elements.push_back(APValue(sInt));
CountElts++;
} else {
llvm::APFloat f(0.0);
if (CountInits < NumInits) {
if (!EvaluateFloat(E->getInit(CountInits), f, Info))
return false;
} else // trailing float zero.
f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy));
Elements.push_back(APValue(f));
CountElts++;
}
CountInits++;
}
return Success(Elements, E);
}
bool
VectorExprEvaluator::ZeroInitialization(const Expr *E) {
const VectorType *VT = E->getType()->getAs<VectorType>();
QualType EltTy = VT->getElementType();
APValue ZeroElement;
if (EltTy->isIntegerType())
ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy));
else
ZeroElement =
APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)));
SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement);
return Success(Elements, E);
}
bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
VisitIgnoredValue(E->getSubExpr());
return ZeroInitialization(E);
}
//===----------------------------------------------------------------------===//
// Array Evaluation
//===----------------------------------------------------------------------===//
namespace {
class ArrayExprEvaluator
: public ExprEvaluatorBase<ArrayExprEvaluator> {
const LValue &This;
APValue &Result;
public:
ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result)
: ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
bool Success(const APValue &V, const Expr *E) {
assert((V.isArray() || V.isLValue()) &&
"expected array or string literal");
Result = V;
return true;
}
bool ZeroInitialization(const Expr *E) {
const ConstantArrayType *CAT =
Info.Ctx.getAsConstantArrayType(E->getType());
if (!CAT)
return Error(E);
Result = APValue(APValue::UninitArray(), 0,
CAT->getSize().getZExtValue());
if (!Result.hasArrayFiller()) return true;
// Zero-initialize all elements.
LValue Subobject = This;
Subobject.addArray(Info, E, CAT);
ImplicitValueInitExpr VIE(CAT->getElementType());
return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE);
}
bool VisitCallExpr(const CallExpr *E) {
return handleCallExpr(E, Result, &This);
}
bool VisitInitListExpr(const InitListExpr *E);
bool VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E,
const LValue &Subobject,
APValue *Value, QualType Type);
};
} // end anonymous namespace
static bool EvaluateArray(const Expr *E, const LValue &This,
APValue &Result, EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isArrayType() && "not an array rvalue");
return ArrayExprEvaluator(Info, This, Result).Visit(E);
}
bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType());
if (!CAT)
return Error(E);
// C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...]
// an appropriately-typed string literal enclosed in braces.
if (E->isStringLiteralInit()) {
LValue LV;
if (!EvaluateLValue(E->getInit(0), LV, Info))
return false;
APValue Val;
LV.moveInto(Val);
return Success(Val, E);
}
bool Success = true;
assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) &&
"zero-initialized array shouldn't have any initialized elts");
APValue Filler;
if (Result.isArray() && Result.hasArrayFiller())
Filler = Result.getArrayFiller();
unsigned NumEltsToInit = E->getNumInits();
unsigned NumElts = CAT->getSize().getZExtValue();
const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : nullptr;
// If the initializer might depend on the array index, run it for each
// array element. For now, just whitelist non-class value-initialization.
if (NumEltsToInit != NumElts && !isa<ImplicitValueInitExpr>(FillerExpr))
NumEltsToInit = NumElts;
Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts);
// If the array was previously zero-initialized, preserve the
// zero-initialized values.
if (!Filler.isUninit()) {
for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I)
Result.getArrayInitializedElt(I) = Filler;
if (Result.hasArrayFiller())
Result.getArrayFiller() = Filler;
}
LValue Subobject = This;
Subobject.addArray(Info, E, CAT);
for (unsigned Index = 0; Index != NumEltsToInit; ++Index) {
const Expr *Init =
Index < E->getNumInits() ? E->getInit(Index) : FillerExpr;
if (!EvaluateInPlace(Result.getArrayInitializedElt(Index),
Info, Subobject, Init) ||
!HandleLValueArrayAdjustment(Info, Init, Subobject,
CAT->getElementType(), 1)) {
if (!Info.noteFailure())
return false;
Success = false;
}
}
if (!Result.hasArrayFiller())
return Success;
// If we get here, we have a trivial filler, which we can just evaluate
// once and splat over the rest of the array elements.
assert(FillerExpr && "no array filler for incomplete init list");
return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject,
FillerExpr) && Success;
}
bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) {
if (E->getCommonExpr() &&
!Evaluate(Info.CurrentCall->createTemporary(E->getCommonExpr(), false),
Info, E->getCommonExpr()->getSourceExpr()))
return false;
auto *CAT = cast<ConstantArrayType>(E->getType()->castAsArrayTypeUnsafe());
uint64_t Elements = CAT->getSize().getZExtValue();
Result = APValue(APValue::UninitArray(), Elements, Elements);
LValue Subobject = This;
Subobject.addArray(Info, E, CAT);
bool Success = true;
for (EvalInfo::ArrayInitLoopIndex Index(Info); Index != Elements; ++Index) {
if (!EvaluateInPlace(Result.getArrayInitializedElt(Index),
Info, Subobject, E->getSubExpr()) ||
!HandleLValueArrayAdjustment(Info, E, Subobject,
CAT->getElementType(), 1)) {
if (!Info.noteFailure())
return false;
Success = false;
}
}
return Success;
}
bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) {
return VisitCXXConstructExpr(E, This, &Result, E->getType());
}
bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
const LValue &Subobject,
APValue *Value,
QualType Type) {
bool HadZeroInit = !Value->isUninit();
if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) {
unsigned N = CAT->getSize().getZExtValue();
// Preserve the array filler if we had prior zero-initialization.
APValue Filler =
HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller()
: APValue();
*Value = APValue(APValue::UninitArray(), N, N);
if (HadZeroInit)
for (unsigned I = 0; I != N; ++I)
Value->getArrayInitializedElt(I) = Filler;
// Initialize the elements.
LValue ArrayElt = Subobject;
ArrayElt.addArray(Info, E, CAT);
for (unsigned I = 0; I != N; ++I)
if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I),
CAT->getElementType()) ||
!HandleLValueArrayAdjustment(Info, E, ArrayElt,
CAT->getElementType(), 1))
return false;
return true;
}
if (!Type->isRecordType())
return Error(E);
return RecordExprEvaluator(Info, Subobject, *Value)
.VisitCXXConstructExpr(E, Type);
}
//===----------------------------------------------------------------------===//
// Integer Evaluation
//
// As a GNU extension, we support casting pointers to sufficiently-wide integer
// types and back in constant folding. Integer values are thus represented
// either as an integer-valued APValue, or as an lvalue-valued APValue.
//===----------------------------------------------------------------------===//
namespace {
class IntExprEvaluator
: public ExprEvaluatorBase<IntExprEvaluator> {
APValue &Result;
public:
IntExprEvaluator(EvalInfo &info, APValue &result)
: ExprEvaluatorBaseTy(info), Result(result) {}
bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) {
assert(E->getType()->isIntegralOrEnumerationType() &&
"Invalid evaluation result.");
assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() &&
"Invalid evaluation result.");
assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
"Invalid evaluation result.");
Result = APValue(SI);
return true;
}
bool Success(const llvm::APSInt &SI, const Expr *E) {
return Success(SI, E, Result);
}
bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) {
assert(E->getType()->isIntegralOrEnumerationType() &&
"Invalid evaluation result.");
assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
"Invalid evaluation result.");
Result = APValue(APSInt(I));
Result.getInt().setIsUnsigned(
E->getType()->isUnsignedIntegerOrEnumerationType());
return true;
}
bool Success(const llvm::APInt &I, const Expr *E) {
return Success(I, E, Result);
}
bool Success(uint64_t Value, const Expr *E, APValue &Result) {
assert(E->getType()->isIntegralOrEnumerationType() &&
"Invalid evaluation result.");
Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType()));
return true;
}
bool Success(uint64_t Value, const Expr *E) {
return Success(Value, E, Result);
}
bool Success(CharUnits Size, const Expr *E) {
return Success(Size.getQuantity(), E);
}
bool Success(const APValue &V, const Expr *E) {
if (V.isLValue() || V.isAddrLabelDiff()) {
Result = V;
return true;
}
return Success(V.getInt(), E);
}
bool ZeroInitialization(const Expr *E) { return Success(0, E); }
//===--------------------------------------------------------------------===//
// Visitor Methods
//===--------------------------------------------------------------------===//
bool VisitIntegerLiteral(const IntegerLiteral *E) {
return Success(E->getValue(), E);
}
bool VisitCharacterLiteral(const CharacterLiteral *E) {
return Success(E->getValue(), E);
}
bool CheckReferencedDecl(const Expr *E, const Decl *D);
bool VisitDeclRefExpr(const DeclRefExpr *E) {
if (CheckReferencedDecl(E, E->getDecl()))
return true;
return ExprEvaluatorBaseTy::VisitDeclRefExpr(E);
}
bool VisitMemberExpr(const MemberExpr *E) {
if (CheckReferencedDecl(E, E->getMemberDecl())) {
VisitIgnoredBaseExpression(E->getBase());
return true;
}
return ExprEvaluatorBaseTy::VisitMemberExpr(E);
}
bool VisitCallExpr(const CallExpr *E);
bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitOffsetOfExpr(const OffsetOfExpr *E);
bool VisitUnaryOperator(const UnaryOperator *E);
bool VisitCastExpr(const CastExpr* E);
bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E);
bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
return Success(E->getValue(), E);
}
bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) {
return Success(E->getValue(), E);
}
bool VisitArrayInitIndexExpr(const ArrayInitIndexExpr *E) {
if (Info.ArrayInitIndex == uint64_t(-1)) {
// We were asked to evaluate this subexpression independent of the
// enclosing ArrayInitLoopExpr. We can't do that.
Info.FFDiag(E);
return false;
}
return Success(Info.ArrayInitIndex, E);
}
// Note, GNU defines __null as an integer, not a pointer.
bool VisitGNUNullExpr(const GNUNullExpr *E) {
return ZeroInitialization(E);
}
bool VisitTypeTraitExpr(const TypeTraitExpr *E) {
return Success(E->getValue(), E);
}
bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) {
return Success(E->getValue(), E);
}
bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) {
return Success(E->getValue(), E);
}
bool VisitUnaryReal(const UnaryOperator *E);
bool VisitUnaryImag(const UnaryOperator *E);
bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E);
bool VisitSizeOfPackExpr(const SizeOfPackExpr *E);
// FIXME: Missing: array subscript of vector, member of vector
};
} // end anonymous namespace
/// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and
/// produce either the integer value or a pointer.
///
/// GCC has a heinous extension which folds casts between pointer types and
/// pointer-sized integral types. We support this by allowing the evaluation of
/// an integer rvalue to produce a pointer (represented as an lvalue) instead.
/// Some simple arithmetic on such values is supported (they are treated much
/// like char*).
static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType());
return IntExprEvaluator(Info, Result).Visit(E);
}
static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) {
APValue Val;
if (!EvaluateIntegerOrLValue(E, Val, Info))
return false;
if (!Val.isInt()) {
// FIXME: It would be better to produce the diagnostic for casting
// a pointer to an integer.
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
Result = Val.getInt();
return true;
}
/// Check whether the given declaration can be directly converted to an integral
/// rvalue. If not, no diagnostic is produced; there are other things we can
/// try.
bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) {
// Enums are integer constant exprs.
if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) {
// Check for signedness/width mismatches between E type and ECD value.
bool SameSign = (ECD->getInitVal().isSigned()
== E->getType()->isSignedIntegerOrEnumerationType());
bool SameWidth = (ECD->getInitVal().getBitWidth()
== Info.Ctx.getIntWidth(E->getType()));
if (SameSign && SameWidth)
return Success(ECD->getInitVal(), E);
else {
// Get rid of mismatch (otherwise Success assertions will fail)
// by computing a new value matching the type of E.
llvm::APSInt Val = ECD->getInitVal();
if (!SameSign)
Val.setIsSigned(!ECD->getInitVal().isSigned());
if (!SameWidth)
Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType()));
return Success(Val, E);
}
}
return false;
}
/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
/// as GCC.
static int EvaluateBuiltinClassifyType(const CallExpr *E,
const LangOptions &LangOpts) {
// The following enum mimics the values returned by GCC.
// FIXME: Does GCC differ between lvalue and rvalue references here?
enum gcc_type_class {
no_type_class = -1,
void_type_class, integer_type_class, char_type_class,
enumeral_type_class, boolean_type_class,
pointer_type_class, reference_type_class, offset_type_class,
real_type_class, complex_type_class,
function_type_class, method_type_class,
record_type_class, union_type_class,
array_type_class, string_type_class,
lang_type_class
};
// If no argument was supplied, default to "no_type_class". This isn't
// ideal, however it is what gcc does.
if (E->getNumArgs() == 0)
return no_type_class;
QualType CanTy = E->getArg(0)->getType().getCanonicalType();
const BuiltinType *BT = dyn_cast<BuiltinType>(CanTy);
switch (CanTy->getTypeClass()) {
#define TYPE(ID, BASE)
#define DEPENDENT_TYPE(ID, BASE) case Type::ID:
#define NON_CANONICAL_TYPE(ID, BASE) case Type::ID:
#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(ID, BASE) case Type::ID:
#include "clang/AST/TypeNodes.def"
llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type");
case Type::Builtin:
switch (BT->getKind()) {
#define BUILTIN_TYPE(ID, SINGLETON_ID)
#define SIGNED_TYPE(ID, SINGLETON_ID) case BuiltinType::ID: return integer_type_class;
#define FLOATING_TYPE(ID, SINGLETON_ID) case BuiltinType::ID: return real_type_class;
#define PLACEHOLDER_TYPE(ID, SINGLETON_ID) case BuiltinType::ID: break;
#include "clang/AST/BuiltinTypes.def"
case BuiltinType::Void:
return void_type_class;
case BuiltinType::Bool:
return boolean_type_class;
case BuiltinType::Char_U: // gcc doesn't appear to use char_type_class
case BuiltinType::UChar:
case BuiltinType::UShort:
case BuiltinType::UInt:
case BuiltinType::ULong:
case BuiltinType::ULongLong:
case BuiltinType::UInt128:
return integer_type_class;
case BuiltinType::NullPtr:
return pointer_type_class;
case BuiltinType::WChar_U:
case BuiltinType::Char16:
case BuiltinType::Char32:
case BuiltinType::ObjCId:
case BuiltinType::ObjCClass:
case BuiltinType::ObjCSel:
#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
case BuiltinType::Id:
#include "clang/Basic/OpenCLImageTypes.def"
case BuiltinType::OCLSampler:
case BuiltinType::OCLEvent:
case BuiltinType::OCLClkEvent:
case BuiltinType::OCLQueue:
case BuiltinType::OCLReserveID:
case BuiltinType::Dependent:
llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type");
};
case Type::Enum:
return LangOpts.CPlusPlus ? enumeral_type_class : integer_type_class;
break;
case Type::Pointer:
return pointer_type_class;
break;
case Type::MemberPointer:
if (CanTy->isMemberDataPointerType())
return offset_type_class;
else {
// We expect member pointers to be either data or function pointers,
// nothing else.
assert(CanTy->isMemberFunctionPointerType());
return method_type_class;
}
case Type::Complex:
return complex_type_class;
case Type::FunctionNoProto:
case Type::FunctionProto:
return LangOpts.CPlusPlus ? function_type_class : pointer_type_class;
case Type::Record:
if (const RecordType *RT = CanTy->getAs<RecordType>()) {
switch (RT->getDecl()->getTagKind()) {
case TagTypeKind::TTK_Struct:
case TagTypeKind::TTK_Class:
case TagTypeKind::TTK_Interface:
return record_type_class;
case TagTypeKind::TTK_Enum:
return LangOpts.CPlusPlus ? enumeral_type_class : integer_type_class;
case TagTypeKind::TTK_Union:
return union_type_class;
}
}
llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type");
case Type::ConstantArray:
case Type::VariableArray:
case Type::IncompleteArray:
return LangOpts.CPlusPlus ? array_type_class : pointer_type_class;
case Type::BlockPointer:
case Type::LValueReference:
case Type::RValueReference:
case Type::Vector:
case Type::ExtVector:
case Type::Auto:
case Type::DeducedTemplateSpecialization:
case Type::ObjCObject:
case Type::ObjCInterface:
case Type::ObjCObjectPointer:
case Type::Pipe:
case Type::Atomic:
llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type");
}
llvm_unreachable("CallExpr::isBuiltinClassifyType(): unimplemented type");
}
/// EvaluateBuiltinConstantPForLValue - Determine the result of
/// __builtin_constant_p when applied to the given lvalue.
///
/// An lvalue is only "constant" if it is a pointer or reference to the first
/// character of a string literal.
template<typename LValue>
static bool EvaluateBuiltinConstantPForLValue(const LValue &LV) {
const Expr *E = LV.getLValueBase().template dyn_cast<const Expr*>();
return E && isa<StringLiteral>(E) && LV.getLValueOffset().isZero();
}
/// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to
/// GCC as we can manage.
static bool EvaluateBuiltinConstantP(ASTContext &Ctx, const Expr *Arg) {
QualType ArgType = Arg->getType();
// __builtin_constant_p always has one operand. The rules which gcc follows
// are not precisely documented, but are as follows:
//
// - If the operand is of integral, floating, complex or enumeration type,
// and can be folded to a known value of that type, it returns 1.
// - If the operand and can be folded to a pointer to the first character
// of a string literal (or such a pointer cast to an integral type), it
// returns 1.
//
// Otherwise, it returns 0.
//
// FIXME: GCC also intends to return 1 for literals of aggregate types, but
// its support for this does not currently work.
if (ArgType->isIntegralOrEnumerationType()) {
Expr::EvalResult Result;
if (!Arg->EvaluateAsRValue(Result, Ctx) || Result.HasSideEffects)
return false;
APValue &V = Result.Val;
if (V.getKind() == APValue::Int)
return true;
if (V.getKind() == APValue::LValue)
return EvaluateBuiltinConstantPForLValue(V);
} else if (ArgType->isFloatingType() || ArgType->isAnyComplexType()) {
return Arg->isEvaluatable(Ctx);
} else if (ArgType->isPointerType() || Arg->isGLValue()) {
LValue LV;
Expr::EvalStatus Status;
EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
if ((Arg->isGLValue() ? EvaluateLValue(Arg, LV, Info)
: EvaluatePointer(Arg, LV, Info)) &&
!Status.HasSideEffects)
return EvaluateBuiltinConstantPForLValue(LV);
}
// Anything else isn't considered to be sufficiently constant.
return false;
}
/// Retrieves the "underlying object type" of the given expression,
/// as used by __builtin_object_size.
static QualType getObjectType(APValue::LValueBase B) {
if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
if (const VarDecl *VD = dyn_cast<VarDecl>(D))
return VD->getType();
} else if (const Expr *E = B.get<const Expr*>()) {
if (isa<CompoundLiteralExpr>(E))
return E->getType();
}
return QualType();
}
/// A more selective version of E->IgnoreParenCasts for
/// tryEvaluateBuiltinObjectSize. This ignores some casts/parens that serve only
/// to change the type of E.
/// Ex. For E = `(short*)((char*)(&foo))`, returns `&foo`
///
/// Always returns an RValue with a pointer representation.
static const Expr *ignorePointerCastsAndParens(const Expr *E) {
assert(E->isRValue() && E->getType()->hasPointerRepresentation());
auto *NoParens = E->IgnoreParens();
auto *Cast = dyn_cast<CastExpr>(NoParens);
if (Cast == nullptr)
return NoParens;
// We only conservatively allow a few kinds of casts, because this code is
// inherently a simple solution that seeks to support the common case.
auto CastKind = Cast->getCastKind();
if (CastKind != CK_NoOp && CastKind != CK_BitCast &&
CastKind != CK_AddressSpaceConversion)
return NoParens;
auto *SubExpr = Cast->getSubExpr();
if (!SubExpr->getType()->hasPointerRepresentation() || !SubExpr->isRValue())
return NoParens;
return ignorePointerCastsAndParens(SubExpr);
}
/// Checks to see if the given LValue's Designator is at the end of the LValue's
/// record layout. e.g.
/// struct { struct { int a, b; } fst, snd; } obj;
/// obj.fst // no
/// obj.snd // yes
/// obj.fst.a // no
/// obj.fst.b // no
/// obj.snd.a // no
/// obj.snd.b // yes
///
/// Please note: this function is specialized for how __builtin_object_size
/// views "objects".
///
/// If this encounters an invalid RecordDecl, it will always return true.
static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
assert(!LVal.Designator.Invalid);
auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD, bool &Invalid) {
const RecordDecl *Parent = FD->getParent();
Invalid = Parent->isInvalidDecl();
if (Invalid || Parent->isUnion())
return true;
const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Parent);
return FD->getFieldIndex() + 1 == Layout.getFieldCount();
};
auto &Base = LVal.getLValueBase();
if (auto *ME = dyn_cast_or_null<MemberExpr>(Base.dyn_cast<const Expr *>())) {
if (auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
bool Invalid;
if (!IsLastOrInvalidFieldDecl(FD, Invalid))
return Invalid;
} else if (auto *IFD = dyn_cast<IndirectFieldDecl>(ME->getMemberDecl())) {
for (auto *FD : IFD->chain()) {
bool Invalid;
if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(FD), Invalid))
return Invalid;
}
}
}
unsigned I = 0;
QualType BaseType = getType(Base);
if (LVal.Designator.FirstEntryIsAnUnsizedArray) {
assert(isBaseAnAllocSizeCall(Base) &&
"Unsized array in non-alloc_size call?");
// If this is an alloc_size base, we should ignore the initial array index
++I;
BaseType = BaseType->castAs<PointerType>()->getPointeeType();
}
for (unsigned E = LVal.Designator.Entries.size(); I != E; ++I) {
const auto &Entry = LVal.Designator.Entries[I];
if (BaseType->isArrayType()) {
// Because __builtin_object_size treats arrays as objects, we can ignore
// the index iff this is the last array in the Designator.
if (I + 1 == E)
return true;
const auto *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(BaseType));
uint64_t Index = Entry.ArrayIndex;
if (Index + 1 != CAT->getSize())
return false;
BaseType = CAT->getElementType();
} else if (BaseType->isAnyComplexType()) {
const auto *CT = BaseType->castAs<ComplexType>();
uint64_t Index = Entry.ArrayIndex;
if (Index != 1)
return false;
BaseType = CT->getElementType();
} else if (auto *FD = getAsField(Entry)) {
bool Invalid;
if (!IsLastOrInvalidFieldDecl(FD, Invalid))
return Invalid;
BaseType = FD->getType();
} else {
assert(getAsBaseClass(Entry) && "Expecting cast to a base class");
return false;
}
}
return true;
}
/// Tests to see if the LValue has a user-specified designator (that isn't
/// necessarily valid). Note that this always returns 'true' if the LValue has
/// an unsized array as its first designator entry, because there's currently no
/// way to tell if the user typed *foo or foo[0].
static bool refersToCompleteObject(const LValue &LVal) {
if (LVal.Designator.Invalid)
return false;
if (!LVal.Designator.Entries.empty())
return LVal.Designator.isMostDerivedAnUnsizedArray();
if (!LVal.InvalidBase)
return true;
// If `E` is a MemberExpr, then the first part of the designator is hiding in
// the LValueBase.
const auto *E = LVal.Base.dyn_cast<const Expr *>();
return !E || !isa<MemberExpr>(E);
}
/// Attempts to detect a user writing into a piece of memory that's impossible
/// to figure out the size of by just using types.
static bool isUserWritingOffTheEnd(const ASTContext &Ctx, const LValue &LVal) {
const SubobjectDesignator &Designator = LVal.Designator;
// Notes:
// - Users can only write off of the end when we have an invalid base. Invalid
// bases imply we don't know where the memory came from.
// - We used to be a bit more aggressive here; we'd only be conservative if
// the array at the end was flexible, or if it had 0 or 1 elements. This
// broke some common standard library extensions (PR30346), but was
// otherwise seemingly fine. It may be useful to reintroduce this behavior
// with some sort of whitelist. OTOH, it seems that GCC is always
// conservative with the last element in structs (if it's an array), so our
// current behavior is more compatible than a whitelisting approach would
// be.
return LVal.InvalidBase &&
Designator.Entries.size() == Designator.MostDerivedPathLength &&
Designator.MostDerivedIsArrayElement &&
isDesignatorAtObjectEnd(Ctx, LVal);
}
/// Converts the given APInt to CharUnits, assuming the APInt is unsigned.
/// Fails if the conversion would cause loss of precision.
static bool convertUnsignedAPIntToCharUnits(const llvm::APInt &Int,
CharUnits &Result) {
auto CharUnitsMax = std::numeric_limits<CharUnits::QuantityType>::max();
if (Int.ugt(CharUnitsMax))
return false;
Result = CharUnits::fromQuantity(Int.getZExtValue());
return true;
}
/// Helper for tryEvaluateBuiltinObjectSize -- Given an LValue, this will
/// determine how many bytes exist from the beginning of the object to either
/// the end of the current subobject, or the end of the object itself, depending
/// on what the LValue looks like + the value of Type.
///
/// If this returns false, the value of Result is undefined.
static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc,
unsigned Type, const LValue &LVal,
CharUnits &EndOffset) {
bool DetermineForCompleteObject = refersToCompleteObject(LVal);
auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) {
if (Ty.isNull() || Ty->isIncompleteType() || Ty->isFunctionType())
return false;
return HandleSizeof(Info, ExprLoc, Ty, Result);
};
// We want to evaluate the size of the entire object. This is a valid fallback
// for when Type=1 and the designator is invalid, because we're asked for an
// upper-bound.
if (!(Type & 1) || LVal.Designator.Invalid || DetermineForCompleteObject) {
// Type=3 wants a lower bound, so we can't fall back to this.
if (Type == 3 && !DetermineForCompleteObject)
return false;
llvm::APInt APEndOffset;
if (isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset))
return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset);
if (LVal.InvalidBase)
return false;
QualType BaseTy = getObjectType(LVal.getLValueBase());
return CheckedHandleSizeof(BaseTy, EndOffset);
}
// We want to evaluate the size of a subobject.
const SubobjectDesignator &Designator = LVal.Designator;
// The following is a moderately common idiom in C:
//
// struct Foo { int a; char c[1]; };
// struct Foo *F = (struct Foo *)malloc(sizeof(struct Foo) + strlen(Bar));
// strcpy(&F->c[0], Bar);
//
// In order to not break too much legacy code, we need to support it.
if (isUserWritingOffTheEnd(Info.Ctx, LVal)) {
// If we can resolve this to an alloc_size call, we can hand that back,
// because we know for certain how many bytes there are to write to.
llvm::APInt APEndOffset;
if (isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset))
return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset);
// If we cannot determine the size of the initial allocation, then we can't
// given an accurate upper-bound. However, we are still able to give
// conservative lower-bounds for Type=3.
if (Type == 1)
return false;
}
CharUnits BytesPerElem;
if (!CheckedHandleSizeof(Designator.MostDerivedType, BytesPerElem))
return false;
// According to the GCC documentation, we want the size of the subobject
// denoted by the pointer. But that's not quite right -- what we actually
// want is the size of the immediately-enclosing array, if there is one.
int64_t ElemsRemaining;
if (Designator.MostDerivedIsArrayElement &&
Designator.Entries.size() == Designator.MostDerivedPathLength) {
uint64_t ArraySize = Designator.getMostDerivedArraySize();
uint64_t ArrayIndex = Designator.Entries.back().ArrayIndex;
ElemsRemaining = ArraySize <= ArrayIndex ? 0 : ArraySize - ArrayIndex;
} else {
ElemsRemaining = Designator.isOnePastTheEnd() ? 0 : 1;
}
EndOffset = LVal.getLValueOffset() + BytesPerElem * ElemsRemaining;
return true;
}
/// \brief Tries to evaluate the __builtin_object_size for @p E. If successful,
/// returns true and stores the result in @p Size.
///
/// If @p WasError is non-null, this will report whether the failure to evaluate
/// is to be treated as an Error in IntExprEvaluator.
static bool tryEvaluateBuiltinObjectSize(const Expr *E, unsigned Type,
EvalInfo &Info, uint64_t &Size) {
// Determine the denoted object.
LValue LVal;
{
// The operand of __builtin_object_size is never evaluated for side-effects.
// If there are any, but we can determine the pointed-to object anyway, then
// ignore the side-effects.
SpeculativeEvaluationRAII SpeculativeEval(Info);
FoldOffsetRAII Fold(Info);
if (E->isGLValue()) {
// It's possible for us to be given GLValues if we're called via
// Expr::tryEvaluateObjectSize.
APValue RVal;
if (!EvaluateAsRValue(Info, E, RVal))
return false;
LVal.setFrom(Info.Ctx, RVal);
} else if (!EvaluatePointer(ignorePointerCastsAndParens(E), LVal, Info,
/*InvalidBaseOK=*/true))
return false;
}
// If we point to before the start of the object, there are no accessible
// bytes.
if (LVal.getLValueOffset().isNegative()) {
Size = 0;
return true;
}
CharUnits EndOffset;
if (!determineEndOffset(Info, E->getExprLoc(), Type, LVal, EndOffset))
return false;
// If we've fallen outside of the end offset, just pretend there's nothing to
// write to/read from.
if (EndOffset <= LVal.getLValueOffset())
Size = 0;
else
Size = (EndOffset - LVal.getLValueOffset()).getQuantity();
return true;
}
bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
if (unsigned BuiltinOp = E->getBuiltinCallee())
return VisitBuiltinCallExpr(E, BuiltinOp);
return ExprEvaluatorBaseTy::VisitCallExpr(E);
}
bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
unsigned BuiltinOp) {
switch (unsigned BuiltinOp = E->getBuiltinCallee()) {
default:
return ExprEvaluatorBaseTy::VisitCallExpr(E);
case Builtin::BI__builtin_object_size: {
// The type was checked when we built the expression.
unsigned Type =
E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
assert(Type <= 3 && "unexpected type");
uint64_t Size;
if (tryEvaluateBuiltinObjectSize(E->getArg(0), Type, Info, Size))
return Success(Size, E);
if (E->getArg(0)->HasSideEffects(Info.Ctx))
return Success((Type & 2) ? 0 : -1, E);
// Expression had no side effects, but we couldn't statically determine the
// size of the referenced object.
switch (Info.EvalMode) {
case EvalInfo::EM_ConstantExpression:
case EvalInfo::EM_PotentialConstantExpression:
case EvalInfo::EM_ConstantFold:
case EvalInfo::EM_EvaluateForOverflow:
case EvalInfo::EM_IgnoreSideEffects:
case EvalInfo::EM_OffsetFold:
// Leave it to IR generation.
return Error(E);
case EvalInfo::EM_ConstantExpressionUnevaluated:
case EvalInfo::EM_PotentialConstantExpressionUnevaluated:
// Reduce it to a constant now.
return Success((Type & 2) ? 0 : -1, E);
}
llvm_unreachable("unexpected EvalMode");
}
case Builtin::BI__builtin_bswap16:
case Builtin::BI__builtin_bswap32:
case Builtin::BI__builtin_bswap64: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
return Success(Val.byteSwap(), E);
}
case Builtin::BI__builtin_classify_type:
return Success(EvaluateBuiltinClassifyType(E, Info.getLangOpts()), E);
// FIXME: BI__builtin_clrsb
// FIXME: BI__builtin_clrsbl
// FIXME: BI__builtin_clrsbll
case Builtin::BI__builtin_clz:
case Builtin::BI__builtin_clzl:
case Builtin::BI__builtin_clzll:
case Builtin::BI__builtin_clzs: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
if (!Val)
return Error(E);
return Success(Val.countLeadingZeros(), E);
}
case Builtin::BI__builtin_constant_p:
return Success(EvaluateBuiltinConstantP(Info.Ctx, E->getArg(0)), E);
case Builtin::BI__builtin_ctz:
case Builtin::BI__builtin_ctzl:
case Builtin::BI__builtin_ctzll:
case Builtin::BI__builtin_ctzs: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
if (!Val)
return Error(E);
return Success(Val.countTrailingZeros(), E);
}
case Builtin::BI__builtin_eh_return_data_regno: {
int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand);
return Success(Operand, E);
}
case Builtin::BI__builtin_expect:
return Visit(E->getArg(0));
case Builtin::BI__builtin_ffs:
case Builtin::BI__builtin_ffsl:
case Builtin::BI__builtin_ffsll: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
unsigned N = Val.countTrailingZeros();
return Success(N == Val.getBitWidth() ? 0 : N + 1, E);
}
case Builtin::BI__builtin_fpclassify: {
APFloat Val(0.0);
if (!EvaluateFloat(E->getArg(5), Val, Info))
return false;
unsigned Arg;
switch (Val.getCategory()) {
case APFloat::fcNaN: Arg = 0; break;
case APFloat::fcInfinity: Arg = 1; break;
case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break;
case APFloat::fcZero: Arg = 4; break;
}
return Visit(E->getArg(Arg));
}
case Builtin::BI__builtin_isinf_sign: {
APFloat Val(0.0);
return EvaluateFloat(E->getArg(0), Val, Info) &&
Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E);
}
case Builtin::BI__builtin_isinf: {
APFloat Val(0.0);
return EvaluateFloat(E->getArg(0), Val, Info) &&
Success(Val.isInfinity() ? 1 : 0, E);
}
case Builtin::BI__builtin_isfinite: {
APFloat Val(0.0);
return EvaluateFloat(E->getArg(0), Val, Info) &&
Success(Val.isFinite() ? 1 : 0, E);
}
case Builtin::BI__builtin_isnan: {
APFloat Val(0.0);
return EvaluateFloat(E->getArg(0), Val, Info) &&
Success(Val.isNaN() ? 1 : 0, E);
}
case Builtin::BI__builtin_isnormal: {
APFloat Val(0.0);
return EvaluateFloat(E->getArg(0), Val, Info) &&
Success(Val.isNormal() ? 1 : 0, E);
}
case Builtin::BI__builtin_parity:
case Builtin::BI__builtin_parityl:
case Builtin::BI__builtin_parityll: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
return Success(Val.countPopulation() % 2, E);
}
case Builtin::BI__builtin_popcount:
case Builtin::BI__builtin_popcountl:
case Builtin::BI__builtin_popcountll: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
return Success(Val.countPopulation(), E);
}
case Builtin::BIstrlen:
case Builtin::BIwcslen:
// A call to strlen is not a constant expression.
if (Info.getLangOpts().CPlusPlus11)
Info.CCEDiag(E, diag::note_constexpr_invalid_function)
<< /*isConstexpr*/0 << /*isConstructor*/0
<< (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
else
Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
// Fall through.
case Builtin::BI__builtin_strlen:
case Builtin::BI__builtin_wcslen: {
// As an extension, we support __builtin_strlen() as a constant expression,
// and support folding strlen() to a constant.
LValue String;
if (!EvaluatePointer(E->getArg(0), String, Info))
return false;
QualType CharTy = E->getArg(0)->getType()->getPointeeType();
// Fast path: if it's a string literal, search the string value.
if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>(
String.getLValueBase().dyn_cast<const Expr *>())) {
// The string literal may have embedded null characters. Find the first
// one and truncate there.
StringRef Str = S->getBytes();
int64_t Off = String.Offset.getQuantity();
if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() &&
S->getCharByteWidth() == 1 &&
// FIXME: Add fast-path for wchar_t too.
Info.Ctx.hasSameUnqualifiedType(CharTy, Info.Ctx.CharTy)) {
Str = Str.substr(Off);
StringRef::size_type Pos = Str.find(0);
if (Pos != StringRef::npos)
Str = Str.substr(0, Pos);
return Success(Str.size(), E);
}
// Fall through to slow path to issue appropriate diagnostic.
}
// Slow path: scan the bytes of the string looking for the terminating 0.
for (uint64_t Strlen = 0; /**/; ++Strlen) {
APValue Char;
if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) ||
!Char.isInt())
return false;
if (!Char.getInt())
return Success(Strlen, E);
if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1))
return false;
}
}
case Builtin::BIstrcmp:
case Builtin::BIwcscmp:
case Builtin::BIstrncmp:
case Builtin::BIwcsncmp:
case Builtin::BImemcmp:
case Builtin::BIwmemcmp:
// A call to strlen is not a constant expression.
if (Info.getLangOpts().CPlusPlus11)
Info.CCEDiag(E, diag::note_constexpr_invalid_function)
<< /*isConstexpr*/0 << /*isConstructor*/0
<< (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
else
Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
// Fall through.
case Builtin::BI__builtin_strcmp:
case Builtin::BI__builtin_wcscmp:
case Builtin::BI__builtin_strncmp:
case Builtin::BI__builtin_wcsncmp:
case Builtin::BI__builtin_memcmp:
case Builtin::BI__builtin_wmemcmp: {
LValue String1, String2;
if (!EvaluatePointer(E->getArg(0), String1, Info) ||
!EvaluatePointer(E->getArg(1), String2, Info))
return false;
QualType CharTy = E->getArg(0)->getType()->getPointeeType();
uint64_t MaxLength = uint64_t(-1);
if (BuiltinOp != Builtin::BIstrcmp &&
BuiltinOp != Builtin::BIwcscmp &&
BuiltinOp != Builtin::BI__builtin_strcmp &&
BuiltinOp != Builtin::BI__builtin_wcscmp) {
APSInt N;
if (!EvaluateInteger(E->getArg(2), N, Info))
return false;
MaxLength = N.getExtValue();
}
bool StopAtNull = (BuiltinOp != Builtin::BImemcmp &&
BuiltinOp != Builtin::BIwmemcmp &&
BuiltinOp != Builtin::BI__builtin_memcmp &&
BuiltinOp != Builtin::BI__builtin_wmemcmp);
for (; MaxLength; --MaxLength) {
APValue Char1, Char2;
if (!handleLValueToRValueConversion(Info, E, CharTy, String1, Char1) ||
!handleLValueToRValueConversion(Info, E, CharTy, String2, Char2) ||
!Char1.isInt() || !Char2.isInt())
return false;
if (Char1.getInt() != Char2.getInt())
return Success(Char1.getInt() < Char2.getInt() ? -1 : 1, E);
if (StopAtNull && !Char1.getInt())
return Success(0, E);
assert(!(StopAtNull && !Char2.getInt()));
if (!HandleLValueArrayAdjustment(Info, E, String1, CharTy, 1) ||
!HandleLValueArrayAdjustment(Info, E, String2, CharTy, 1))
return false;
}
// We hit the strncmp / memcmp limit.
return Success(0, E);
}
case Builtin::BI__atomic_always_lock_free:
case Builtin::BI__atomic_is_lock_free:
case Builtin::BI__c11_atomic_is_lock_free: {
APSInt SizeVal;
if (!EvaluateInteger(E->getArg(0), SizeVal, Info))
return false;
// For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power
// of two less than the maximum inline atomic width, we know it is
// lock-free. If the size isn't a power of two, or greater than the
// maximum alignment where we promote atomics, we know it is not lock-free
// (at least not in the sense of atomic_is_lock_free). Otherwise,
// the answer can only be determined at runtime; for example, 16-byte
// atomics have lock-free implementations on some, but not all,
// x86-64 processors.
// Check power-of-two.
CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue());
if (Size.isPowerOfTwo()) {
// Check against inlining width.
unsigned InlineWidthBits =
Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth();
if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) {
if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free ||
Size == CharUnits::One() ||
E->getArg(1)->isNullPointerConstant(Info.Ctx,
Expr::NPC_NeverValueDependent))
// OK, we will inline appropriately-aligned operations of this size,
// and _Atomic(T) is appropriately-aligned.
return Success(1, E);
QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()->
castAs<PointerType>()->getPointeeType();
if (!PointeeType->isIncompleteType() &&
Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) {
// OK, we will inline operations on this object.
return Success(1, E);
}
}
}
return BuiltinOp == Builtin::BI__atomic_always_lock_free ?
Success(0, E) : Error(E);
}
}
}
static bool HasSameBase(const LValue &A, const LValue &B) {
if (!A.getLValueBase())
return !B.getLValueBase();
if (!B.getLValueBase())
return false;
if (A.getLValueBase().getOpaqueValue() !=
B.getLValueBase().getOpaqueValue()) {
const Decl *ADecl = GetLValueBaseDecl(A);
if (!ADecl)
return false;
const Decl *BDecl = GetLValueBaseDecl(B);
if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl())
return false;
}
return IsGlobalLValue(A.getLValueBase()) ||
A.getLValueCallIndex() == B.getLValueCallIndex();
}
/// \brief Determine whether this is a pointer past the end of the complete
/// object referred to by the lvalue.
static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx,
const LValue &LV) {
// A null pointer can be viewed as being "past the end" but we don't
// choose to look at it that way here.
if (!LV.getLValueBase())
return false;
// If the designator is valid and refers to a subobject, we're not pointing
// past the end.
if (!LV.getLValueDesignator().Invalid &&
!LV.getLValueDesignator().isOnePastTheEnd())
return false;
// A pointer to an incomplete type might be past-the-end if the type's size is
// zero. We cannot tell because the type is incomplete.
QualType Ty = getType(LV.getLValueBase());
if (Ty->isIncompleteType())
return true;
// We're a past-the-end pointer if we point to the byte after the object,
// no matter what our type or path is.
auto Size = Ctx.getTypeSizeInChars(Ty);
return LV.getLValueOffset() == Size;
}
namespace {
/// \brief Data recursive integer evaluator of certain binary operators.
///
/// We use a data recursive algorithm for binary operators so that we are able
/// to handle extreme cases of chained binary operators without causing stack
/// overflow.
class DataRecursiveIntBinOpEvaluator {
struct EvalResult {
APValue Val;
bool Failed;
EvalResult() : Failed(false) { }
void swap(EvalResult &RHS) {
Val.swap(RHS.Val);
Failed = RHS.Failed;
RHS.Failed = false;
}
};
struct Job {
const Expr *E;
EvalResult LHSResult; // meaningful only for binary operator expression.
enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind;
Job() = default;
Job(Job &&) = default;
void startSpeculativeEval(EvalInfo &Info) {
SpecEvalRAII = SpeculativeEvaluationRAII(Info);
}
private:
SpeculativeEvaluationRAII SpecEvalRAII;
};
SmallVector<Job, 16> Queue;
IntExprEvaluator &IntEval;
EvalInfo &Info;
APValue &FinalResult;
public:
DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result)
: IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { }
/// \brief True if \param E is a binary operator that we are going to handle
/// data recursively.
/// We handle binary operators that are comma, logical, or that have operands
/// with integral or enumeration type.
static bool shouldEnqueue(const BinaryOperator *E) {
return E->getOpcode() == BO_Comma ||
E->isLogicalOp() ||
(E->isRValue() &&
E->getType()->isIntegralOrEnumerationType() &&
E->getLHS()->getType()->isIntegralOrEnumerationType() &&
E->getRHS()->getType()->isIntegralOrEnumerationType());
}
bool Traverse(const BinaryOperator *E) {
enqueue(E);
EvalResult PrevResult;
while (!Queue.empty())
process(PrevResult);
if (PrevResult.Failed) return false;
FinalResult.swap(PrevResult.Val);
return true;
}
private:
bool Success(uint64_t Value, const Expr *E, APValue &Result) {
return IntEval.Success(Value, E, Result);
}
bool Success(const APSInt &Value, const Expr *E, APValue &Result) {
return IntEval.Success(Value, E, Result);
}
bool Error(const Expr *E) {
return IntEval.Error(E);
}
bool Error(const Expr *E, diag::kind D) {
return IntEval.Error(E, D);
}
OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
return Info.CCEDiag(E, D);
}
// \brief Returns true if visiting the RHS is necessary, false otherwise.
bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
bool &SuppressRHSDiags);
bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
const BinaryOperator *E, APValue &Result);
void EvaluateExpr(const Expr *E, EvalResult &Result) {
Result.Failed = !Evaluate(Result.Val, Info, E);
if (Result.Failed)
Result.Val = APValue();
}
void process(EvalResult &Result);
void enqueue(const Expr *E) {
E = E->IgnoreParens();
Queue.resize(Queue.size()+1);
Queue.back().E = E;
Queue.back().Kind = Job::AnyExprKind;
}
};
}
bool DataRecursiveIntBinOpEvaluator::
VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
bool &SuppressRHSDiags) {
if (E->getOpcode() == BO_Comma) {
// Ignore LHS but note if we could not evaluate it.
if (LHSResult.Failed)
return Info.noteSideEffect();
return true;
}
if (E->isLogicalOp()) {
bool LHSAsBool;
if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) {
// We were able to evaluate the LHS, see if we can get away with not
// evaluating the RHS: 0 && X -> 0, 1 || X -> 1
if (LHSAsBool == (E->getOpcode() == BO_LOr)) {
Success(LHSAsBool, E, LHSResult.Val);
return false; // Ignore RHS
}
} else {
LHSResult.Failed = true;
// Since we weren't able to evaluate the left hand side, it
// might have had side effects.
if (!Info.noteSideEffect())
return false;
// We can't evaluate the LHS; however, sometimes the result
// is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
// Don't ignore RHS and suppress diagnostics from this arm.
SuppressRHSDiags = true;
}
return true;
}
assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
E->getRHS()->getType()->isIntegralOrEnumerationType());
if (LHSResult.Failed && !Info.noteFailure())
return false; // Ignore RHS;
return true;
}
static void addOrSubLValueAsInteger(APValue &LVal, const APSInt &Index,
bool IsSub) {
// Compute the new offset in the appropriate width, wrapping at 64 bits.
// FIXME: When compiling for a 32-bit target, we should use 32-bit
// offsets.
assert(!LVal.hasLValuePath() && "have designator for integer lvalue");
CharUnits &Offset = LVal.getLValueOffset();
uint64_t Offset64 = Offset.getQuantity();
uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
Offset = CharUnits::fromQuantity(IsSub ? Offset64 - Index64
: Offset64 + Index64);
}
bool DataRecursiveIntBinOpEvaluator::
VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
const BinaryOperator *E, APValue &Result) {
if (E->getOpcode() == BO_Comma) {
if (RHSResult.Failed)
return false;
Result = RHSResult.Val;
return true;
}
if (E->isLogicalOp()) {
bool lhsResult, rhsResult;
bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult);
bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult);
if (LHSIsOK) {
if (RHSIsOK) {
if (E->getOpcode() == BO_LOr)
return Success(lhsResult || rhsResult, E, Result);
else
return Success(lhsResult && rhsResult, E, Result);
}
} else {
if (RHSIsOK) {
// We can't evaluate the LHS; however, sometimes the result
// is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
if (rhsResult == (E->getOpcode() == BO_LOr))
return Success(rhsResult, E, Result);
}
}
return false;
}
assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
E->getRHS()->getType()->isIntegralOrEnumerationType());
if (LHSResult.Failed || RHSResult.Failed)
return false;
const APValue &LHSVal = LHSResult.Val;
const APValue &RHSVal = RHSResult.Val;
// Handle cases like (unsigned long)&a + 4.
if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) {
Result = LHSVal;
addOrSubLValueAsInteger(Result, RHSVal.getInt(), E->getOpcode() == BO_Sub);
return true;
}
// Handle cases like 4 + (unsigned long)&a
if (E->getOpcode() == BO_Add &&
RHSVal.isLValue() && LHSVal.isInt()) {
Result = RHSVal;
addOrSubLValueAsInteger(Result, LHSVal.getInt(), /*IsSub*/false);
return true;
}
if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) {
// Handle (intptr_t)&&A - (intptr_t)&&B.
if (!LHSVal.getLValueOffset().isZero() ||
!RHSVal.getLValueOffset().isZero())
return false;
const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>();
const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>();
if (!LHSExpr || !RHSExpr)
return false;
const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr);
const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr);
if (!LHSAddrExpr || !RHSAddrExpr)
return false;
// Make sure both labels come from the same function.
if (LHSAddrExpr->getLabel()->getDeclContext() !=
RHSAddrExpr->getLabel()->getDeclContext())
return false;
Result = APValue(LHSAddrExpr, RHSAddrExpr);
return true;
}
// All the remaining cases expect both operands to be an integer
if (!LHSVal.isInt() || !RHSVal.isInt())
return Error(E);
// Set up the width and signedness manually, in case it can't be deduced
// from the operation we're performing.
// FIXME: Don't do this in the cases where we can deduce it.
APSInt Value(Info.Ctx.getIntWidth(E->getType()),
E->getType()->isUnsignedIntegerOrEnumerationType());
if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(),
RHSVal.getInt(), Value))
return false;
return Success(Value, E, Result);
}
void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) {
Job &job = Queue.back();
switch (job.Kind) {
case Job::AnyExprKind: {
if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) {
if (shouldEnqueue(Bop)) {
job.Kind = Job::BinOpKind;
enqueue(Bop->getLHS());
return;
}
}
EvaluateExpr(job.E, Result);
Queue.pop_back();
return;
}
case Job::BinOpKind: {
const BinaryOperator *Bop = cast<BinaryOperator>(job.E);
bool SuppressRHSDiags = false;
if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) {
Queue.pop_back();
return;
}
if (SuppressRHSDiags)
job.startSpeculativeEval(Info);
job.LHSResult.swap(Result);
job.Kind = Job::BinOpVisitedLHSKind;
enqueue(Bop->getRHS());
return;
}
case Job::BinOpVisitedLHSKind: {
const BinaryOperator *Bop = cast<BinaryOperator>(job.E);
EvalResult RHS;
RHS.swap(Result);
Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val);
Queue.pop_back();
return;
}
}
llvm_unreachable("Invalid Job::Kind!");
}
namespace {
/// Used when we determine that we should fail, but can keep evaluating prior to
/// noting that we had a failure.
class DelayedNoteFailureRAII {
EvalInfo &Info;
bool NoteFailure;
public:
DelayedNoteFailureRAII(EvalInfo &Info, bool NoteFailure = true)
: Info(Info), NoteFailure(NoteFailure) {}
~DelayedNoteFailureRAII() {
if (NoteFailure) {
bool ContinueAfterFailure = Info.noteFailure();
(void)ContinueAfterFailure;
assert(ContinueAfterFailure &&
"Shouldn't have kept evaluating on failure.");
}
}
};
}
bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
// We don't call noteFailure immediately because the assignment happens after
// we evaluate LHS and RHS.
if (!Info.keepEvaluatingAfterFailure() && E->isAssignmentOp())
return Error(E);
DelayedNoteFailureRAII MaybeNoteFailureLater(Info, E->isAssignmentOp());
if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E))
return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E);
QualType LHSTy = E->getLHS()->getType();
QualType RHSTy = E->getRHS()->getType();
if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) {
ComplexValue LHS, RHS;
bool LHSOK;
if (E->isAssignmentOp()) {
LValue LV;
EvaluateLValue(E->getLHS(), LV, Info);
LHSOK = false;
} else if (LHSTy->isRealFloatingType()) {
LHSOK = EvaluateFloat(E->getLHS(), LHS.FloatReal, Info);
if (LHSOK) {
LHS.makeComplexFloat();
LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics());
}
} else {
LHSOK = EvaluateComplex(E->getLHS(), LHS, Info);
}
if (!LHSOK && !Info.noteFailure())
return false;
if (E->getRHS()->getType()->isRealFloatingType()) {
if (!EvaluateFloat(E->getRHS(), RHS.FloatReal, Info) || !LHSOK)
return false;
RHS.makeComplexFloat();
RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics());
} else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK)
return false;
if (LHS.isComplexFloat()) {
APFloat::cmpResult CR_r =
LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal());
APFloat::cmpResult CR_i =
LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag());
if (E->getOpcode() == BO_EQ)
return Success((CR_r == APFloat::cmpEqual &&
CR_i == APFloat::cmpEqual), E);
else {
assert(E->getOpcode() == BO_NE &&
"Invalid complex comparison.");
return Success(((CR_r == APFloat::cmpGreaterThan ||
CR_r == APFloat::cmpLessThan ||
CR_r == APFloat::cmpUnordered) ||
(CR_i == APFloat::cmpGreaterThan ||
CR_i == APFloat::cmpLessThan ||
CR_i == APFloat::cmpUnordered)), E);
}
} else {
if (E->getOpcode() == BO_EQ)
return Success((LHS.getComplexIntReal() == RHS.getComplexIntReal() &&
LHS.getComplexIntImag() == RHS.getComplexIntImag()), E);
else {
assert(E->getOpcode() == BO_NE &&
"Invalid compex comparison.");
return Success((LHS.getComplexIntReal() != RHS.getComplexIntReal() ||
LHS.getComplexIntImag() != RHS.getComplexIntImag()), E);
}
}
}
if (LHSTy->isRealFloatingType() &&
RHSTy->isRealFloatingType()) {
APFloat RHS(0.0), LHS(0.0);
bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info);
if (!LHSOK && !Info.noteFailure())
return false;
if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK)
return false;
APFloat::cmpResult CR = LHS.compare(RHS);
switch (E->getOpcode()) {
default:
llvm_unreachable("Invalid binary operator!");
case BO_LT:
return Success(CR == APFloat::cmpLessThan, E);
case BO_GT:
return Success(CR == APFloat::cmpGreaterThan, E);
case BO_LE:
return Success(CR == APFloat::cmpLessThan || CR == APFloat::cmpEqual, E);
case BO_GE:
return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpEqual,
E);
case BO_EQ:
return Success(CR == APFloat::cmpEqual, E);
case BO_NE:
return Success(CR == APFloat::cmpGreaterThan
|| CR == APFloat::cmpLessThan
|| CR == APFloat::cmpUnordered, E);
}
}
if (LHSTy->isPointerType() && RHSTy->isPointerType()) {
if (E->getOpcode() == BO_Sub || E->isComparisonOp()) {
LValue LHSValue, RHSValue;
bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info);
if (!LHSOK && !Info.noteFailure())
return false;
if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK)
return false;
// Reject differing bases from the normal codepath; we special-case
// comparisons to null.
if (!HasSameBase(LHSValue, RHSValue)) {
if (E->getOpcode() == BO_Sub) {
// Handle &&A - &&B.
if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero())
return Error(E);
const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr*>();
const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr*>();
if (!LHSExpr || !RHSExpr)
return Error(E);
const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr);
const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr);
if (!LHSAddrExpr || !RHSAddrExpr)
return Error(E);
// Make sure both labels come from the same function.
if (LHSAddrExpr->getLabel()->getDeclContext() !=
RHSAddrExpr->getLabel()->getDeclContext())
return Error(E);
return Success(APValue(LHSAddrExpr, RHSAddrExpr), E);
}
// Inequalities and subtractions between unrelated pointers have
// unspecified or undefined behavior.
if (!E->isEqualityOp())
return Error(E);
// A constant address may compare equal to the address of a symbol.
// The one exception is that address of an object cannot compare equal
// to a null pointer constant.
if ((!LHSValue.Base && !LHSValue.Offset.isZero()) ||
(!RHSValue.Base && !RHSValue.Offset.isZero()))
return Error(E);
// It's implementation-defined whether distinct literals will have
// distinct addresses. In clang, the result of such a comparison is
// unspecified, so it is not a constant expression. However, we do know
// that the address of a literal will be non-null.
if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) &&
LHSValue.Base && RHSValue.Base)
return Error(E);
// We can't tell whether weak symbols will end up pointing to the same
// object.
if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue))
return Error(E);
// We can't compare the address of the start of one object with the
// past-the-end address of another object, per C++ DR1652.
if ((LHSValue.Base && LHSValue.Offset.isZero() &&
isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue)) ||
(RHSValue.Base && RHSValue.Offset.isZero() &&
isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue)))
return Error(E);
// We can't tell whether an object is at the same address as another
// zero sized object.
if ((RHSValue.Base && isZeroSized(LHSValue)) ||
(LHSValue.Base && isZeroSized(RHSValue)))
return Error(E);
// Pointers with different bases cannot represent the same object.
// (Note that clang defaults to -fmerge-all-constants, which can
// lead to inconsistent results for comparisons involving the address
// of a constant; this generally doesn't matter in practice.)
return Success(E->getOpcode() == BO_NE, E);
}
const CharUnits &LHSOffset = LHSValue.getLValueOffset();
const CharUnits &RHSOffset = RHSValue.getLValueOffset();
SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
if (E->getOpcode() == BO_Sub) {
// C++11 [expr.add]p6:
// Unless both pointers point to elements of the same array object, or
// one past the last element of the array object, the behavior is
// undefined.
if (!LHSDesignator.Invalid && !RHSDesignator.Invalid &&
!AreElementsOfSameArray(getType(LHSValue.Base),
LHSDesignator, RHSDesignator))
CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array);
QualType Type = E->getLHS()->getType();
QualType ElementType = Type->getAs<PointerType>()->getPointeeType();
CharUnits ElementSize;
if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize))
return false;
// As an extension, a type may have zero size (empty struct or union in
// C, array of zero length). Pointer subtraction in such cases has
// undefined behavior, so is not constant.
if (ElementSize.isZero()) {
Info.FFDiag(E, diag::note_constexpr_pointer_subtraction_zero_size)
<< ElementType;
return false;
}
// FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime,
// and produce incorrect results when it overflows. Such behavior
// appears to be non-conforming, but is common, so perhaps we should
// assume the standard intended for such cases to be undefined behavior
// and check for them.
// Compute (LHSOffset - RHSOffset) / Size carefully, checking for
// overflow in the final conversion to ptrdiff_t.
APSInt LHS(
llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false);
APSInt RHS(
llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false);
APSInt ElemSize(
llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true), false);
APSInt TrueResult = (LHS - RHS) / ElemSize;
APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType()));
if (Result.extend(65) != TrueResult &&
!HandleOverflow(Info, E, TrueResult, E->getType()))
return false;
return Success(Result, E);
}
// C++11 [expr.rel]p3:
// Pointers to void (after pointer conversions) can be compared, with a
// result defined as follows: If both pointers represent the same
// address or are both the null pointer value, the result is true if the
// operator is <= or >= and false otherwise; otherwise the result is
// unspecified.
// We interpret this as applying to pointers to *cv* void.
if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset &&
E->isRelationalOp())
CCEDiag(E, diag::note_constexpr_void_comparison);
// C++11 [expr.rel]p2:
// - If two pointers point to non-static data members of the same object,
// or to subobjects or array elements fo such members, recursively, the
// pointer to the later declared member compares greater provided the
// two members have the same access control and provided their class is
// not a union.
// [...]
// - Otherwise pointer comparisons are unspecified.
if (!LHSDesignator.Invalid && !RHSDesignator.Invalid &&
E->isRelationalOp()) {
bool WasArrayIndex;
unsigned Mismatch =
FindDesignatorMismatch(getType(LHSValue.Base), LHSDesignator,
RHSDesignator, WasArrayIndex);
// At the point where the designators diverge, the comparison has a
// specified value if:
// - we are comparing array indices
// - we are comparing fields of a union, or fields with the same access
// Otherwise, the result is unspecified and thus the comparison is not a
// constant expression.
if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() &&
Mismatch < RHSDesignator.Entries.size()) {
const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]);
const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]);
if (!LF && !RF)
CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes);
else if (!LF)
CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
<< getAsBaseClass(LHSDesignator.Entries[Mismatch])
<< RF->getParent() << RF;
else if (!RF)
CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
<< getAsBaseClass(RHSDesignator.Entries[Mismatch])
<< LF->getParent() << LF;
else if (!LF->getParent()->isUnion() &&
LF->getAccess() != RF->getAccess())
CCEDiag(E, diag::note_constexpr_pointer_comparison_differing_access)
<< LF << LF->getAccess() << RF << RF->getAccess()
<< LF->getParent();
}
}
// The comparison here must be unsigned, and performed with the same
// width as the pointer.
unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy);
uint64_t CompareLHS = LHSOffset.getQuantity();
uint64_t CompareRHS = RHSOffset.getQuantity();
assert(PtrSize <= 64 && "Unexpected pointer width");
uint64_t Mask = ~0ULL >> (64 - PtrSize);
CompareLHS &= Mask;
CompareRHS &= Mask;
// If there is a base and this is a relational operator, we can only
// compare pointers within the object in question; otherwise, the result
// depends on where the object is located in memory.
if (!LHSValue.Base.isNull() && E->isRelationalOp()) {
QualType BaseTy = getType(LHSValue.Base);
if (BaseTy->isIncompleteType())
return Error(E);
CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy);
uint64_t OffsetLimit = Size.getQuantity();
if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit)
return Error(E);
}
switch (E->getOpcode()) {
default: llvm_unreachable("missing comparison operator");
case BO_LT: return Success(CompareLHS < CompareRHS, E);
case BO_GT: return Success(CompareLHS > CompareRHS, E);
case BO_LE: return Success(CompareLHS <= CompareRHS, E);
case BO_GE: return Success(CompareLHS >= CompareRHS, E);
case BO_EQ: return Success(CompareLHS == CompareRHS, E);
case BO_NE: return Success(CompareLHS != CompareRHS, E);
}
}
}
if (LHSTy->isMemberPointerType()) {
assert(E->isEqualityOp() && "unexpected member pointer operation");
assert(RHSTy->isMemberPointerType() && "invalid comparison");
MemberPtr LHSValue, RHSValue;
bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info);
if (!LHSOK && !Info.noteFailure())
return false;
if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK)
return false;
// C++11 [expr.eq]p2:
// If both operands are null, they compare equal. Otherwise if only one is
// null, they compare unequal.
if (!LHSValue.getDecl() || !RHSValue.getDecl()) {
bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl();
return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E);
}
// Otherwise if either is a pointer to a virtual member function, the
// result is unspecified.
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl()))
if (MD->isVirtual())
CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl()))
if (MD->isVirtual())
CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
// Otherwise they compare equal if and only if they would refer to the
// same member of the same most derived object or the same subobject if
// they were dereferenced with a hypothetical object of the associated
// class type.
bool Equal = LHSValue == RHSValue;
return Success(E->getOpcode() == BO_EQ ? Equal : !Equal, E);
}
if (LHSTy->isNullPtrType()) {
assert(E->isComparisonOp() && "unexpected nullptr operation");
assert(RHSTy->isNullPtrType() && "missing pointer conversion");
// C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t
// are compared, the result is true of the operator is <=, >= or ==, and
// false otherwise.
BinaryOperator::Opcode Opcode = E->getOpcode();
return Success(Opcode == BO_EQ || Opcode == BO_LE || Opcode == BO_GE, E);
}
assert((!LHSTy->isIntegralOrEnumerationType() ||
!RHSTy->isIntegralOrEnumerationType()) &&
"DataRecursiveIntBinOpEvaluator should have handled integral types");
// We can't continue from here for non-integral types.
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
}
/// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with
/// a result as the expression's type.
bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr(
const UnaryExprOrTypeTraitExpr *E) {
switch(E->getKind()) {
case UETT_AlignOf: {
if (E->isArgumentType())
return Success(GetAlignOfType(Info, E->getArgumentType()), E);
else
return Success(GetAlignOfExpr(Info, E->getArgumentExpr()), E);
}
case UETT_VecStep: {
QualType Ty = E->getTypeOfArgument();
if (Ty->isVectorType()) {
unsigned n = Ty->castAs<VectorType>()->getNumElements();
// The vec_step built-in functions that take a 3-component
// vector return 4. (OpenCL 1.1 spec 6.11.12)
if (n == 3)
n = 4;
return Success(n, E);
} else
return Success(1, E);
}
case UETT_SizeOf: {
QualType SrcTy = E->getTypeOfArgument();
// C++ [expr.sizeof]p2: "When applied to a reference or a reference type,
// the result is the size of the referenced type."
if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>())
SrcTy = Ref->getPointeeType();
CharUnits Sizeof;
if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof))
return false;
return Success(Sizeof, E);
}
case UETT_OpenMPRequiredSimdAlign:
assert(E->isArgumentType());
return Success(
Info.Ctx.toCharUnitsFromBits(
Info.Ctx.getOpenMPDefaultSimdAlign(E->getArgumentType()))
.getQuantity(),
E);
}
llvm_unreachable("unknown expr/type trait");
}
bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) {
CharUnits Result;
unsigned n = OOE->getNumComponents();
if (n == 0)
return Error(OOE);
QualType CurrentType = OOE->getTypeSourceInfo()->getType();
for (unsigned i = 0; i != n; ++i) {
OffsetOfNode ON = OOE->getComponent(i);
switch (ON.getKind()) {
case OffsetOfNode::Array: {
const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex());
APSInt IdxResult;
if (!EvaluateInteger(Idx, IdxResult, Info))
return false;
const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType);
if (!AT)
return Error(OOE);
CurrentType = AT->getElementType();
CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType);
Result += IdxResult.getSExtValue() * ElementSize;
break;
}
case OffsetOfNode::Field: {
FieldDecl *MemberDecl = ON.getField();
const RecordType *RT = CurrentType->getAs<RecordType>();
if (!RT)
return Error(OOE);
RecordDecl *RD = RT->getDecl();
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
unsigned i = MemberDecl->getFieldIndex();
assert(i < RL.getFieldCount() && "offsetof field in wrong type");
Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i));
CurrentType = MemberDecl->getType().getNonReferenceType();
break;
}
case OffsetOfNode::Identifier:
llvm_unreachable("dependent __builtin_offsetof");
case OffsetOfNode::Base: {
CXXBaseSpecifier *BaseSpec = ON.getBase();
if (BaseSpec->isVirtual())
return Error(OOE);
// Find the layout of the class whose base we are looking into.
const RecordType *RT = CurrentType->getAs<RecordType>();
if (!RT)
return Error(OOE);
RecordDecl *RD = RT->getDecl();
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
// Find the base class itself.
CurrentType = BaseSpec->getType();
const RecordType *BaseRT = CurrentType->getAs<RecordType>();
if (!BaseRT)
return Error(OOE);
// Add the offset to the base.
Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl()));
break;
}
}
}
return Success(Result, OOE);
}
bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
switch (E->getOpcode()) {
default:
// Address, indirect, pre/post inc/dec, etc are not valid constant exprs.
// See C99 6.6p3.
return Error(E);
case UO_Extension:
// FIXME: Should extension allow i-c-e extension expressions in its scope?
// If so, we could clear the diagnostic ID.
return Visit(E->getSubExpr());
case UO_Plus:
// The result is just the value.
return Visit(E->getSubExpr());
case UO_Minus: {
if (!Visit(E->getSubExpr()))
return false;
if (!Result.isInt()) return Error(E);
const APSInt &Value = Result.getInt();
if (Value.isSigned() && Value.isMinSignedValue() &&
!HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1),
E->getType()))
return false;
return Success(-Value, E);
}
case UO_Not: {
if (!Visit(E->getSubExpr()))
return false;
if (!Result.isInt()) return Error(E);
return Success(~Result.getInt(), E);
}
case UO_LNot: {
bool bres;
if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
return false;
return Success(!bres, E);
}
}
}
/// HandleCast - This is used to evaluate implicit or explicit casts where the
/// result type is integer.
bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
const Expr *SubExpr = E->getSubExpr();
QualType DestType = E->getType();
QualType SrcType = SubExpr->getType();
switch (E->getCastKind()) {
case CK_BaseToDerived:
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase:
case CK_Dynamic:
case CK_ToUnion:
case CK_ArrayToPointerDecay:
case CK_FunctionToPointerDecay:
case CK_NullToPointer:
case CK_NullToMemberPointer:
case CK_BaseToDerivedMemberPointer:
case CK_DerivedToBaseMemberPointer:
case CK_ReinterpretMemberPointer:
case CK_ConstructorConversion:
case CK_IntegralToPointer:
case CK_ToVoid:
case CK_VectorSplat:
case CK_IntegralToFloating:
case CK_FloatingCast:
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:
case CK_ObjCObjectLValueCast:
case CK_FloatingRealToComplex:
case CK_FloatingComplexToReal:
case CK_FloatingComplexCast:
case CK_FloatingComplexToIntegralComplex:
case CK_IntegralRealToComplex:
case CK_IntegralComplexCast:
case CK_IntegralComplexToFloatingComplex:
case CK_BuiltinFnToFnPtr:
case CK_ZeroToOCLEvent:
case CK_ZeroToOCLQueue:
case CK_NonAtomicToAtomic:
case CK_AddressSpaceConversion:
case CK_IntToOCLSampler:
llvm_unreachable("invalid cast kind for integral value");
case CK_BitCast:
case CK_Dependent:
case CK_LValueBitCast:
case CK_ARCProduceObject:
case CK_ARCConsumeObject:
case CK_ARCReclaimReturnedObject:
case CK_ARCExtendBlockObject:
case CK_CopyAndAutoreleaseBlockObject:
return Error(E);
case CK_UserDefinedConversion:
case CK_LValueToRValue:
case CK_AtomicToNonAtomic:
case CK_NoOp:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_MemberPointerToBoolean:
case CK_PointerToBoolean:
case CK_IntegralToBoolean:
case CK_FloatingToBoolean:
case CK_BooleanToSignedIntegral:
case CK_FloatingComplexToBoolean:
case CK_IntegralComplexToBoolean: {
bool BoolResult;
if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info))
return false;
uint64_t IntResult = BoolResult;
if (BoolResult && E->getCastKind() == CK_BooleanToSignedIntegral)
IntResult = (uint64_t)-1;
return Success(IntResult, E);
}
case CK_IntegralCast: {
if (!Visit(SubExpr))
return false;
if (!Result.isInt()) {
// Allow casts of address-of-label differences if they are no-ops
// or narrowing. (The narrowing case isn't actually guaranteed to
// be constant-evaluatable except in some narrow cases which are hard
// to detect here. We let it through on the assumption the user knows
// what they are doing.)
if (Result.isAddrLabelDiff())
return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType);
// Only allow casts of lvalues if they are lossless.
return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType);
}
return Success(HandleIntToIntCast(Info, E, DestType, SrcType,
Result.getInt()), E);
}
case CK_PointerToIntegral: {
CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
LValue LV;
if (!EvaluatePointer(SubExpr, LV, Info))
return false;
if (LV.getLValueBase()) {
// Only allow based lvalue casts if they are lossless.
// FIXME: Allow a larger integer size than the pointer size, and allow
// narrowing back down to pointer width in subsequent integral casts.
// FIXME: Check integer type's active bits, not its type size.
if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType))
return Error(E);
LV.Designator.setInvalid();
LV.moveInto(Result);
return true;
}
uint64_t V;
if (LV.isNullPointer())
V = Info.Ctx.getTargetNullPointerValue(SrcType);
else
V = LV.getLValueOffset().getQuantity();
APSInt AsInt = Info.Ctx.MakeIntValue(V, SrcType);
return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E);
}
case CK_IntegralComplexToReal: {
ComplexValue C;
if (!EvaluateComplex(SubExpr, C, Info))
return false;
return Success(C.getComplexIntReal(), E);
}
case CK_FloatingToIntegral: {
APFloat F(0.0);
if (!EvaluateFloat(SubExpr, F, Info))
return false;
APSInt Value;
if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value))
return false;
return Success(Value, E);
}
}
llvm_unreachable("unknown cast resulting in integral value");
}
bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isAnyComplexType()) {
ComplexValue LV;
if (!EvaluateComplex(E->getSubExpr(), LV, Info))
return false;
if (!LV.isComplexInt())
return Error(E);
return Success(LV.getComplexIntReal(), E);
}
return Visit(E->getSubExpr());
}
bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isComplexIntegerType()) {
ComplexValue LV;
if (!EvaluateComplex(E->getSubExpr(), LV, Info))
return false;
if (!LV.isComplexInt())
return Error(E);
return Success(LV.getComplexIntImag(), E);
}
VisitIgnoredValue(E->getSubExpr());
return Success(0, E);
}
bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) {
return Success(E->getPackLength(), E);
}
bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) {
return Success(E->getValue(), E);
}
//===----------------------------------------------------------------------===//
// Float Evaluation
//===----------------------------------------------------------------------===//
namespace {
class FloatExprEvaluator
: public ExprEvaluatorBase<FloatExprEvaluator> {
APFloat &Result;
public:
FloatExprEvaluator(EvalInfo &info, APFloat &result)
: ExprEvaluatorBaseTy(info), Result(result) {}
bool Success(const APValue &V, const Expr *e) {
Result = V.getFloat();
return true;
}
bool ZeroInitialization(const Expr *E) {
Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType()));
return true;
}
bool VisitCallExpr(const CallExpr *E);
bool VisitUnaryOperator(const UnaryOperator *E);
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitFloatingLiteral(const FloatingLiteral *E);
bool VisitCastExpr(const CastExpr *E);
bool VisitUnaryReal(const UnaryOperator *E);
bool VisitUnaryImag(const UnaryOperator *E);
// FIXME: Missing: array subscript of vector, member of vector
};
} // end anonymous namespace
static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isRealFloatingType());
return FloatExprEvaluator(Info, Result).Visit(E);
}
static bool TryEvaluateBuiltinNaN(const ASTContext &Context,
QualType ResultTy,
const Expr *Arg,
bool SNaN,
llvm::APFloat &Result) {
const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts());
if (!S) return false;
const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy);
llvm::APInt fill;
// Treat empty strings as if they were zero.
if (S->getString().empty())
fill = llvm::APInt(32, 0);
else if (S->getString().getAsInteger(0, fill))
return false;
if (Context.getTargetInfo().isNan2008()) {
if (SNaN)
Result = llvm::APFloat::getSNaN(Sem, false, &fill);
else
Result = llvm::APFloat::getQNaN(Sem, false, &fill);
} else {
// Prior to IEEE 754-2008, architectures were allowed to choose whether
// the first bit of their significand was set for qNaN or sNaN. MIPS chose
// a different encoding to what became a standard in 2008, and for pre-
// 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as
// sNaN. This is now known as "legacy NaN" encoding.
if (SNaN)
Result = llvm::APFloat::getQNaN(Sem, false, &fill);
else
Result = llvm::APFloat::getSNaN(Sem, false, &fill);
}
return true;
}
bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
switch (E->getBuiltinCallee()) {
default:
return ExprEvaluatorBaseTy::VisitCallExpr(E);
case Builtin::BI__builtin_huge_val:
case Builtin::BI__builtin_huge_valf:
case Builtin::BI__builtin_huge_vall:
case Builtin::BI__builtin_inf:
case Builtin::BI__builtin_inff:
case Builtin::BI__builtin_infl: {
const llvm::fltSemantics &Sem =
Info.Ctx.getFloatTypeSemantics(E->getType());
Result = llvm::APFloat::getInf(Sem);
return true;
}
case Builtin::BI__builtin_nans:
case Builtin::BI__builtin_nansf:
case Builtin::BI__builtin_nansl:
if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
true, Result))
return Error(E);
return true;
case Builtin::BI__builtin_nan:
case Builtin::BI__builtin_nanf:
case Builtin::BI__builtin_nanl:
// If this is __builtin_nan() turn this into a nan, otherwise we
// can't constant fold it.
if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
false, Result))
return Error(E);
return true;
case Builtin::BI__builtin_fabs:
case Builtin::BI__builtin_fabsf:
case Builtin::BI__builtin_fabsl:
if (!EvaluateFloat(E->getArg(0), Result, Info))
return false;
if (Result.isNegative())
Result.changeSign();
return true;
// FIXME: Builtin::BI__builtin_powi
// FIXME: Builtin::BI__builtin_powif
// FIXME: Builtin::BI__builtin_powil
case Builtin::BI__builtin_copysign:
case Builtin::BI__builtin_copysignf:
case Builtin::BI__builtin_copysignl: {
APFloat RHS(0.);
if (!EvaluateFloat(E->getArg(0), Result, Info) ||
!EvaluateFloat(E->getArg(1), RHS, Info))
return false;
Result.copySign(RHS);
return true;
}
}
}
bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isAnyComplexType()) {
ComplexValue CV;
if (!EvaluateComplex(E->getSubExpr(), CV, Info))
return false;
Result = CV.FloatReal;
return true;
}
return Visit(E->getSubExpr());
}
bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isAnyComplexType()) {
ComplexValue CV;
if (!EvaluateComplex(E->getSubExpr(), CV, Info))
return false;
Result = CV.FloatImag;
return true;
}
VisitIgnoredValue(E->getSubExpr());
const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType());
Result = llvm::APFloat::getZero(Sem);
return true;
}
bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
switch (E->getOpcode()) {
default: return Error(E);
case UO_Plus:
return EvaluateFloat(E->getSubExpr(), Result, Info);
case UO_Minus:
if (!EvaluateFloat(E->getSubExpr(), Result, Info))
return false;
Result.changeSign();
return true;
}
}
bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
APFloat RHS(0.0);
bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info);
if (!LHSOK && !Info.noteFailure())
return false;
return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK &&
handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS);
}
bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) {
Result = E->getValue();
return true;
}
bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) {
const Expr* SubExpr = E->getSubExpr();
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_IntegralToFloating: {
APSInt IntResult;
return EvaluateInteger(SubExpr, IntResult, Info) &&
HandleIntToFloatCast(Info, E, SubExpr->getType(), IntResult,
E->getType(), Result);
}
case CK_FloatingCast: {
if (!Visit(SubExpr))
return false;
return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(),
Result);
}
case CK_FloatingComplexToReal: {
ComplexValue V;
if (!EvaluateComplex(SubExpr, V, Info))
return false;
Result = V.getComplexFloatReal();
return true;
}
}
}
//===----------------------------------------------------------------------===//
// Complex Evaluation (for float and integer)
//===----------------------------------------------------------------------===//
namespace {
class ComplexExprEvaluator
: public ExprEvaluatorBase<ComplexExprEvaluator> {
ComplexValue &Result;
public:
ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result)
: ExprEvaluatorBaseTy(info), Result(Result) {}
bool Success(const APValue &V, const Expr *e) {
Result.setFrom(V);
return true;
}
bool ZeroInitialization(const Expr *E);
//===--------------------------------------------------------------------===//
// Visitor Methods
//===--------------------------------------------------------------------===//
bool VisitImaginaryLiteral(const ImaginaryLiteral *E);
bool VisitCastExpr(const CastExpr *E);
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitUnaryOperator(const UnaryOperator *E);
bool VisitInitListExpr(const InitListExpr *E);
};
} // end anonymous namespace
static bool EvaluateComplex(const Expr *E, ComplexValue &Result,
EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isAnyComplexType());
return ComplexExprEvaluator(Info, Result).Visit(E);
}
bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) {
QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType();
if (ElemTy->isRealFloatingType()) {
Result.makeComplexFloat();
APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy));
Result.FloatReal = Zero;
Result.FloatImag = Zero;
} else {
Result.makeComplexInt();
APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy);
Result.IntReal = Zero;
Result.IntImag = Zero;
}
return true;
}
bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) {
const Expr* SubExpr = E->getSubExpr();
if (SubExpr->getType()->isRealFloatingType()) {
Result.makeComplexFloat();
APFloat &Imag = Result.FloatImag;
if (!EvaluateFloat(SubExpr, Imag, Info))
return false;
Result.FloatReal = APFloat(Imag.getSemantics());
return true;
} else {
assert(SubExpr->getType()->isIntegerType() &&
"Unexpected imaginary literal.");
Result.makeComplexInt();
APSInt &Imag = Result.IntImag;
if (!EvaluateInteger(SubExpr, Imag, Info))
return false;
Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned());
return true;
}
}
bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
case CK_BitCast:
case CK_BaseToDerived:
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase:
case CK_Dynamic:
case CK_ToUnion:
case CK_ArrayToPointerDecay:
case CK_FunctionToPointerDecay:
case CK_NullToPointer:
case CK_NullToMemberPointer:
case CK_BaseToDerivedMemberPointer:
case CK_DerivedToBaseMemberPointer:
case CK_MemberPointerToBoolean:
case CK_ReinterpretMemberPointer:
case CK_ConstructorConversion:
case CK_IntegralToPointer:
case CK_PointerToIntegral:
case CK_PointerToBoolean:
case CK_ToVoid:
case CK_VectorSplat:
case CK_IntegralCast:
case CK_BooleanToSignedIntegral:
case CK_IntegralToBoolean:
case CK_IntegralToFloating:
case CK_FloatingToIntegral:
case CK_FloatingToBoolean:
case CK_FloatingCast:
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:
case CK_ObjCObjectLValueCast:
case CK_FloatingComplexToReal:
case CK_FloatingComplexToBoolean:
case CK_IntegralComplexToReal:
case CK_IntegralComplexToBoolean:
case CK_ARCProduceObject:
case CK_ARCConsumeObject:
case CK_ARCReclaimReturnedObject:
case CK_ARCExtendBlockObject:
case CK_CopyAndAutoreleaseBlockObject:
case CK_BuiltinFnToFnPtr:
case CK_ZeroToOCLEvent:
case CK_ZeroToOCLQueue:
case CK_NonAtomicToAtomic:
case CK_AddressSpaceConversion:
case CK_IntToOCLSampler:
llvm_unreachable("invalid cast kind for complex value");
case CK_LValueToRValue:
case CK_AtomicToNonAtomic:
case CK_NoOp:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_Dependent:
case CK_LValueBitCast:
case CK_UserDefinedConversion:
return Error(E);
case CK_FloatingRealToComplex: {
APFloat &Real = Result.FloatReal;
if (!EvaluateFloat(E->getSubExpr(), Real, Info))
return false;
Result.makeComplexFloat();
Result.FloatImag = APFloat(Real.getSemantics());
return true;
}
case CK_FloatingComplexCast: {
if (!Visit(E->getSubExpr()))
return false;
QualType To = E->getType()->getAs<ComplexType>()->getElementType();
QualType From
= E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType();
return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) &&
HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag);
}
case CK_FloatingComplexToIntegralComplex: {
if (!Visit(E->getSubExpr()))
return false;
QualType To = E->getType()->getAs<ComplexType>()->getElementType();
QualType From
= E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType();
Result.makeComplexInt();
return HandleFloatToIntCast(Info, E, From, Result.FloatReal,
To, Result.IntReal) &&
HandleFloatToIntCast(Info, E, From, Result.FloatImag,
To, Result.IntImag);
}
case CK_IntegralRealToComplex: {
APSInt &Real = Result.IntReal;
if (!EvaluateInteger(E->getSubExpr(), Real, Info))
return false;
Result.makeComplexInt();
Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned());
return true;
}
case CK_IntegralComplexCast: {
if (!Visit(E->getSubExpr()))
return false;
QualType To = E->getType()->getAs<ComplexType>()->getElementType();
QualType From
= E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType();
Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal);
Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag);
return true;
}
case CK_IntegralComplexToFloatingComplex: {
if (!Visit(E->getSubExpr()))
return false;
QualType To = E->getType()->castAs<ComplexType>()->getElementType();
QualType From
= E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
Result.makeComplexFloat();
return HandleIntToFloatCast(Info, E, From, Result.IntReal,
To, Result.FloatReal) &&
HandleIntToFloatCast(Info, E, From, Result.IntImag,
To, Result.FloatImag);
}
}
llvm_unreachable("unknown cast resulting in complex value");
}
bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
// Track whether the LHS or RHS is real at the type system level. When this is
// the case we can simplify our evaluation strategy.
bool LHSReal = false, RHSReal = false;
bool LHSOK;
if (E->getLHS()->getType()->isRealFloatingType()) {
LHSReal = true;
APFloat &Real = Result.FloatReal;
LHSOK = EvaluateFloat(E->getLHS(), Real, Info);
if (LHSOK) {
Result.makeComplexFloat();
Result.FloatImag = APFloat(Real.getSemantics());
}
} else {
LHSOK = Visit(E->getLHS());
}
if (!LHSOK && !Info.noteFailure())
return false;
ComplexValue RHS;
if (E->getRHS()->getType()->isRealFloatingType()) {
RHSReal = true;
APFloat &Real = RHS.FloatReal;
if (!EvaluateFloat(E->getRHS(), Real, Info) || !LHSOK)
return false;
RHS.makeComplexFloat();
RHS.FloatImag = APFloat(Real.getSemantics());
} else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK)
return false;
assert(!(LHSReal && RHSReal) &&
"Cannot have both operands of a complex operation be real.");
switch (E->getOpcode()) {
default: return Error(E);
case BO_Add:
if (Result.isComplexFloat()) {
Result.getComplexFloatReal().add(RHS.getComplexFloatReal(),
APFloat::rmNearestTiesToEven);
if (LHSReal)
Result.getComplexFloatImag() = RHS.getComplexFloatImag();
else if (!RHSReal)
Result.getComplexFloatImag().add(RHS.getComplexFloatImag(),
APFloat::rmNearestTiesToEven);
} else {
Result.getComplexIntReal() += RHS.getComplexIntReal();
Result.getComplexIntImag() += RHS.getComplexIntImag();
}
break;
case BO_Sub:
if (Result.isComplexFloat()) {
Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(),
APFloat::rmNearestTiesToEven);
if (LHSReal) {
Result.getComplexFloatImag() = RHS.getComplexFloatImag();
Result.getComplexFloatImag().changeSign();
} else if (!RHSReal) {
Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(),
APFloat::rmNearestTiesToEven);
}
} else {
Result.getComplexIntReal() -= RHS.getComplexIntReal();
Result.getComplexIntImag() -= RHS.getComplexIntImag();
}
break;
case BO_Mul:
if (Result.isComplexFloat()) {
// This is an implementation of complex multiplication according to the
// constraints laid out in C11 Annex G. The implemantion uses the
// following naming scheme:
// (a + ib) * (c + id)
ComplexValue LHS = Result;
APFloat &A = LHS.getComplexFloatReal();
APFloat &B = LHS.getComplexFloatImag();
APFloat &C = RHS.getComplexFloatReal();
APFloat &D = RHS.getComplexFloatImag();
APFloat &ResR = Result.getComplexFloatReal();
APFloat &ResI = Result.getComplexFloatImag();
if (LHSReal) {
assert(!RHSReal && "Cannot have two real operands for a complex op!");
ResR = A * C;
ResI = A * D;
} else if (RHSReal) {
ResR = C * A;
ResI = C * B;
} else {
// In the fully general case, we need to handle NaNs and infinities
// robustly.
APFloat AC = A * C;
APFloat BD = B * D;
APFloat AD = A * D;
APFloat BC = B * C;
ResR = AC - BD;
ResI = AD + BC;
if (ResR.isNaN() && ResI.isNaN()) {
bool Recalc = false;
if (A.isInfinity() || B.isInfinity()) {
A = APFloat::copySign(
APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A);
B = APFloat::copySign(
APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B);
if (C.isNaN())
C = APFloat::copySign(APFloat(C.getSemantics()), C);
if (D.isNaN())
D = APFloat::copySign(APFloat(D.getSemantics()), D);
Recalc = true;
}
if (C.isInfinity() || D.isInfinity()) {
C = APFloat::copySign(
APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C);
D = APFloat::copySign(
APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D);
if (A.isNaN())
A = APFloat::copySign(APFloat(A.getSemantics()), A);
if (B.isNaN())
B = APFloat::copySign(APFloat(B.getSemantics()), B);
Recalc = true;
}
if (!Recalc && (AC.isInfinity() || BD.isInfinity() ||
AD.isInfinity() || BC.isInfinity())) {
if (A.isNaN())
A = APFloat::copySign(APFloat(A.getSemantics()), A);
if (B.isNaN())
B = APFloat::copySign(APFloat(B.getSemantics()), B);
if (C.isNaN())
C = APFloat::copySign(APFloat(C.getSemantics()), C);
if (D.isNaN())
D = APFloat::copySign(APFloat(D.getSemantics()), D);
Recalc = true;
}
if (Recalc) {
ResR = APFloat::getInf(A.getSemantics()) * (A * C - B * D);
ResI = APFloat::getInf(A.getSemantics()) * (A * D + B * C);
}
}
}
} else {
ComplexValue LHS = Result;
Result.getComplexIntReal() =
(LHS.getComplexIntReal() * RHS.getComplexIntReal() -
LHS.getComplexIntImag() * RHS.getComplexIntImag());
Result.getComplexIntImag() =
(LHS.getComplexIntReal() * RHS.getComplexIntImag() +
LHS.getComplexIntImag() * RHS.getComplexIntReal());
}
break;
case BO_Div:
if (Result.isComplexFloat()) {
// This is an implementation of complex division according to the
// constraints laid out in C11 Annex G. The implemantion uses the
// following naming scheme:
// (a + ib) / (c + id)
ComplexValue LHS = Result;
APFloat &A = LHS.getComplexFloatReal();
APFloat &B = LHS.getComplexFloatImag();
APFloat &C = RHS.getComplexFloatReal();
APFloat &D = RHS.getComplexFloatImag();
APFloat &ResR = Result.getComplexFloatReal();
APFloat &ResI = Result.getComplexFloatImag();
if (RHSReal) {
ResR = A / C;
ResI = B / C;
} else {
if (LHSReal) {
// No real optimizations we can do here, stub out with zero.
B = APFloat::getZero(A.getSemantics());
}
int DenomLogB = 0;
APFloat MaxCD = maxnum(abs(C), abs(D));
if (MaxCD.isFinite()) {
DenomLogB = ilogb(MaxCD);
C = scalbn(C, -DenomLogB, APFloat::rmNearestTiesToEven);
D = scalbn(D, -DenomLogB, APFloat::rmNearestTiesToEven);
}
APFloat Denom = C * C + D * D;
ResR = scalbn((A * C + B * D) / Denom, -DenomLogB,
APFloat::rmNearestTiesToEven);
ResI = scalbn((B * C - A * D) / Denom, -DenomLogB,
APFloat::rmNearestTiesToEven);
if (ResR.isNaN() && ResI.isNaN()) {
if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) {
ResR = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * A;
ResI = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * B;
} else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() &&
D.isFinite()) {
A = APFloat::copySign(
APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A);
B = APFloat::copySign(
APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B);
ResR = APFloat::getInf(ResR.getSemantics()) * (A * C + B * D);
ResI = APFloat::getInf(ResI.getSemantics()) * (B * C - A * D);
} else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) {
C = APFloat::copySign(
APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C);
D = APFloat::copySign(
APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D);
ResR = APFloat::getZero(ResR.getSemantics()) * (A * C + B * D);
ResI = APFloat::getZero(ResI.getSemantics()) * (B * C - A * D);
}
}
}
} else {
if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0)
return Error(E, diag::note_expr_divide_by_zero);
ComplexValue LHS = Result;
APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() +
RHS.getComplexIntImag() * RHS.getComplexIntImag();
Result.getComplexIntReal() =
(LHS.getComplexIntReal() * RHS.getComplexIntReal() +
LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den;
Result.getComplexIntImag() =
(LHS.getComplexIntImag() * RHS.getComplexIntReal() -
LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den;
}
break;
}
return true;
}
bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
// Get the operand value into 'Result'.
if (!Visit(E->getSubExpr()))
return false;
switch (E->getOpcode()) {
default:
return Error(E);
case UO_Extension:
return true;
case UO_Plus:
// The result is always just the subexpr.
return true;
case UO_Minus:
if (Result.isComplexFloat()) {
Result.getComplexFloatReal().changeSign();
Result.getComplexFloatImag().changeSign();
}
else {
Result.getComplexIntReal() = -Result.getComplexIntReal();
Result.getComplexIntImag() = -Result.getComplexIntImag();
}
return true;
case UO_Not:
if (Result.isComplexFloat())
Result.getComplexFloatImag().changeSign();
else
Result.getComplexIntImag() = -Result.getComplexIntImag();
return true;
}
}
bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
if (E->getNumInits() == 2) {
if (E->getType()->isComplexType()) {
Result.makeComplexFloat();
if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info))
return false;
if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info))
return false;
} else {
Result.makeComplexInt();
if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info))
return false;
if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info))
return false;
}
return true;
}
return ExprEvaluatorBaseTy::VisitInitListExpr(E);
}
//===----------------------------------------------------------------------===//
// Atomic expression evaluation, essentially just handling the NonAtomicToAtomic
// implicit conversion.
//===----------------------------------------------------------------------===//
namespace {
class AtomicExprEvaluator :
public ExprEvaluatorBase<AtomicExprEvaluator> {
const LValue *This;
APValue &Result;
public:
AtomicExprEvaluator(EvalInfo &Info, const LValue *This, APValue &Result)
: ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
bool Success(const APValue &V, const Expr *E) {
Result = V;
return true;
}
bool ZeroInitialization(const Expr *E) {
ImplicitValueInitExpr VIE(
E->getType()->castAs<AtomicType>()->getValueType());
// For atomic-qualified class (and array) types in C++, initialize the
// _Atomic-wrapped subobject directly, in-place.
return This ? EvaluateInPlace(Result, Info, *This, &VIE)
: Evaluate(Result, Info, &VIE);
}
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_NonAtomicToAtomic:
return This ? EvaluateInPlace(Result, Info, *This, E->getSubExpr())
: Evaluate(Result, Info, E->getSubExpr());
}
}
};
} // end anonymous namespace
static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isAtomicType());
return AtomicExprEvaluator(Info, This, Result).Visit(E);
}
//===----------------------------------------------------------------------===//
// Void expression evaluation, primarily for a cast to void on the LHS of a
// comma operator
//===----------------------------------------------------------------------===//
namespace {
class VoidExprEvaluator
: public ExprEvaluatorBase<VoidExprEvaluator> {
public:
VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {}
bool Success(const APValue &V, const Expr *e) { return true; }
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_ToVoid:
VisitIgnoredValue(E->getSubExpr());
return true;
}
}
bool VisitCallExpr(const CallExpr *E) {
switch (E->getBuiltinCallee()) {
default:
return ExprEvaluatorBaseTy::VisitCallExpr(E);
case Builtin::BI__assume:
case Builtin::BI__builtin_assume:
// The argument is not evaluated!
return true;
}
}
};
} // end anonymous namespace
static bool EvaluateVoid(const Expr *E, EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isVoidType());
return VoidExprEvaluator(Info).Visit(E);
}
//===----------------------------------------------------------------------===//
// Top level Expr::EvaluateAsRValue method.
//===----------------------------------------------------------------------===//
static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
// In C, function designators are not lvalues, but we evaluate them as if they
// are.
QualType T = E->getType();
if (E->isGLValue() || T->isFunctionType()) {
LValue LV;
if (!EvaluateLValue(E, LV, Info))
return false;
LV.moveInto(Result);
} else if (T->isVectorType()) {
if (!EvaluateVector(E, Result, Info))
return false;
} else if (T->isIntegralOrEnumerationType()) {
if (!IntExprEvaluator(Info, Result).Visit(E))
return false;
} else if (T->hasPointerRepresentation()) {
LValue LV;
if (!EvaluatePointer(E, LV, Info))
return false;
LV.moveInto(Result);
} else if (T->isRealFloatingType()) {
llvm::APFloat F(0.0);
if (!EvaluateFloat(E, F, Info))
return false;
Result = APValue(F);
} else if (T->isAnyComplexType()) {
ComplexValue C;
if (!EvaluateComplex(E, C, Info))
return false;
C.moveInto(Result);
} else if (T->isMemberPointerType()) {
MemberPtr P;
if (!EvaluateMemberPointer(E, P, Info))
return false;
P.moveInto(Result);
return true;
} else if (T->isArrayType()) {
LValue LV;
LV.set(E, Info.CurrentCall->Index);
APValue &Value = Info.CurrentCall->createTemporary(E, false);
if (!EvaluateArray(E, LV, Value, Info))
return false;
Result = Value;
} else if (T->isRecordType()) {
LValue LV;
LV.set(E, Info.CurrentCall->Index);
APValue &Value = Info.CurrentCall->createTemporary(E, false);
if (!EvaluateRecord(E, LV, Value, Info))
return false;
Result = Value;
} else if (T->isVoidType()) {
if (!Info.getLangOpts().CPlusPlus11)
Info.CCEDiag(E, diag::note_constexpr_nonliteral)
<< E->getType();
if (!EvaluateVoid(E, Info))
return false;
} else if (T->isAtomicType()) {
QualType Unqual = T.getAtomicUnqualifiedType();
if (Unqual->isArrayType() || Unqual->isRecordType()) {
LValue LV;
LV.set(E, Info.CurrentCall->Index);
APValue &Value = Info.CurrentCall->createTemporary(E, false);
if (!EvaluateAtomic(E, &LV, Value, Info))
return false;
} else {
if (!EvaluateAtomic(E, nullptr, Result, Info))
return false;
}
} else if (Info.getLangOpts().CPlusPlus11) {
Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType();
return false;
} else {
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
return true;
}
/// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some
/// cases, the in-place evaluation is essential, since later initializers for
/// an object can indirectly refer to subobjects which were initialized earlier.
static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This,
const Expr *E, bool AllowNonLiteralTypes) {
assert(!E->isValueDependent());
if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This))
return false;
if (E->isRValue()) {
// Evaluate arrays and record types in-place, so that later initializers can
// refer to earlier-initialized members of the object.
QualType T = E->getType();
if (T->isArrayType())
return EvaluateArray(E, This, Result, Info);
else if (T->isRecordType())
return EvaluateRecord(E, This, Result, Info);
else if (T->isAtomicType()) {
QualType Unqual = T.getAtomicUnqualifiedType();
if (Unqual->isArrayType() || Unqual->isRecordType())
return EvaluateAtomic(E, &This, Result, Info);
}
}
// For any other type, in-place evaluation is unimportant.
return Evaluate(Result, Info, E);
}
/// EvaluateAsRValue - Try to evaluate this expression, performing an implicit
/// lvalue-to-rvalue cast if it is an lvalue.
static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) {
if (E->getType().isNull())
return false;
if (!CheckLiteralType(Info, E))
return false;
if (!::Evaluate(Result, Info, E))
return false;
if (E->isGLValue()) {
LValue LV;
LV.setFrom(Info.Ctx, Result);
if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
return false;
}
// Check this core constant expression is a constant expression.
return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result);
}
static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result,
const ASTContext &Ctx, bool &IsConst,
bool IsCheckingForOverflow) {
// Fast-path evaluations of integer literals, since we sometimes see files
// containing vast quantities of these.
if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) {
Result.Val = APValue(APSInt(L->getValue(),
L->getType()->isUnsignedIntegerType()));
IsConst = true;
return true;
}
// This case should be rare, but we need to check it before we check on
// the type below.
if (Exp->getType().isNull()) {
IsConst = false;
return true;
}
// FIXME: Evaluating values of large array and record types can cause
// performance problems. Only do so in C++11 for now.
if (Exp->isRValue() && (Exp->getType()->isArrayType() ||
Exp->getType()->isRecordType()) &&
!Ctx.getLangOpts().CPlusPlus11 && !IsCheckingForOverflow) {
IsConst = false;
return true;
}
return false;
}
/// EvaluateAsRValue - Return true if this is a constant which we can fold using
/// any crazy technique (that has nothing to do with language standards) that
/// we want to. If this function returns true, it returns the folded constant
/// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion
/// will be applied to the result.
bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx) const {
bool IsConst;
if (FastEvaluateAsRValue(this, Result, Ctx, IsConst, false))
return IsConst;
EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
return ::EvaluateAsRValue(Info, this, Result.Val);
}
bool Expr::EvaluateAsBooleanCondition(bool &Result,
const ASTContext &Ctx) const {
EvalResult Scratch;
return EvaluateAsRValue(Scratch, Ctx) &&
HandleConversionToBool(Scratch.Val, Result);
}
static bool hasUnacceptableSideEffect(Expr::EvalStatus &Result,
Expr::SideEffectsKind SEK) {
return (SEK < Expr::SE_AllowSideEffects && Result.HasSideEffects) ||
(SEK < Expr::SE_AllowUndefinedBehavior && Result.HasUndefinedBehavior);
}
bool Expr::EvaluateAsInt(APSInt &Result, const ASTContext &Ctx,
SideEffectsKind AllowSideEffects) const {
if (!getType()->isIntegralOrEnumerationType())
return false;
EvalResult ExprResult;
if (!EvaluateAsRValue(ExprResult, Ctx) || !ExprResult.Val.isInt() ||
hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
return false;
Result = ExprResult.Val.getInt();
return true;
}
bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx,
SideEffectsKind AllowSideEffects) const {
if (!getType()->isRealFloatingType())
return false;
EvalResult ExprResult;
if (!EvaluateAsRValue(ExprResult, Ctx) || !ExprResult.Val.isFloat() ||
hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
return false;
Result = ExprResult.Val.getFloat();
return true;
}
bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx) const {
EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold);
LValue LV;
if (!EvaluateLValue(this, LV, Info) || Result.HasSideEffects ||
!CheckLValueConstantExpression(Info, getExprLoc(),
Ctx.getLValueReferenceType(getType()), LV))
return false;
LV.moveInto(Result.Val);
return true;
}
bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx,
const VarDecl *VD,
SmallVectorImpl<PartialDiagnosticAt> &Notes) const {
// FIXME: Evaluating initializers for large array and record types can cause
// performance problems. Only do so in C++11 for now.
if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) &&
!Ctx.getLangOpts().CPlusPlus11)
return false;
Expr::EvalStatus EStatus;
EStatus.Diag = &Notes;
EvalInfo InitInfo(Ctx, EStatus, VD->isConstexpr()
? EvalInfo::EM_ConstantExpression
: EvalInfo::EM_ConstantFold);
InitInfo.setEvaluatingDecl(VD, Value);
LValue LVal;
LVal.set(VD);
// C++11 [basic.start.init]p2:
// Variables with static storage duration or thread storage duration shall be
// zero-initialized before any other initialization takes place.
// This behavior is not present in C.
if (Ctx.getLangOpts().CPlusPlus && !VD->hasLocalStorage() &&
!VD->getType()->isReferenceType()) {
ImplicitValueInitExpr VIE(VD->getType());
if (!EvaluateInPlace(Value, InitInfo, LVal, &VIE,
/*AllowNonLiteralTypes=*/true))
return false;
}
if (!EvaluateInPlace(Value, InitInfo, LVal, this,
/*AllowNonLiteralTypes=*/true) ||
EStatus.HasSideEffects)
return false;
return CheckConstantExpression(InitInfo, VD->getLocation(), VD->getType(),
Value);
}
/// isEvaluatable - Call EvaluateAsRValue to see if this expression can be
/// constant folded, but discard the result.
bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const {
EvalResult Result;
return EvaluateAsRValue(Result, Ctx) &&
!hasUnacceptableSideEffect(Result, SEK);
}
APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx,
SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
EvalResult EvalResult;
EvalResult.Diag = Diag;
bool Result = EvaluateAsRValue(EvalResult, Ctx);
(void)Result;
assert(Result && "Could not evaluate expression");
assert(EvalResult.Val.isInt() && "Expression did not evaluate to integer");
return EvalResult.Val.getInt();
}
void Expr::EvaluateForOverflow(const ASTContext &Ctx) const {
bool IsConst;
EvalResult EvalResult;
if (!FastEvaluateAsRValue(this, EvalResult, Ctx, IsConst, true)) {
EvalInfo Info(Ctx, EvalResult, EvalInfo::EM_EvaluateForOverflow);
(void)::EvaluateAsRValue(Info, this, EvalResult.Val);
}
}
bool Expr::EvalResult::isGlobalLValue() const {
assert(Val.isLValue());
return IsGlobalLValue(Val.getLValueBase());
}
/// isIntegerConstantExpr - this recursive routine will test if an expression is
/// an integer constant expression.
/// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero,
/// comma, etc
// CheckICE - This function does the fundamental ICE checking: the returned
// ICEDiag contains an ICEKind indicating whether the expression is an ICE,
// and a (possibly null) SourceLocation indicating the location of the problem.
//
// Note that to reduce code duplication, this helper does no evaluation
// itself; the caller checks whether the expression is evaluatable, and
// in the rare cases where CheckICE actually cares about the evaluated
// value, it calls into Evaluate.
namespace {
enum ICEKind {
/// This expression is an ICE.
IK_ICE,
/// This expression is not an ICE, but if it isn't evaluated, it's
/// a legal subexpression for an ICE. This return value is used to handle
/// the comma operator in C99 mode, and non-constant subexpressions.
IK_ICEIfUnevaluated,
/// This expression is not an ICE, and is not a legal subexpression for one.
IK_NotICE
};
struct ICEDiag {
ICEKind Kind;
SourceLocation Loc;
ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {}
};
}
static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); }
static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; }
static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) {
Expr::EvalResult EVResult;
if (!E->EvaluateAsRValue(EVResult, Ctx) || EVResult.HasSideEffects ||
!EVResult.Val.isInt())
return ICEDiag(IK_NotICE, E->getLocStart());
return NoDiag();
}
static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
assert(!E->isValueDependent() && "Should not see value dependent exprs!");
if (!E->getType()->isIntegralOrEnumerationType())
return ICEDiag(IK_NotICE, E->getLocStart());
switch (E->getStmtClass()) {
#define ABSTRACT_STMT(Node)
#define STMT(Node, Base) case Expr::Node##Class:
#define EXPR(Node, Base)
#include "clang/AST/StmtNodes.inc"
case Expr::PredefinedExprClass:
case Expr::FloatingLiteralClass:
case Expr::ImaginaryLiteralClass:
case Expr::StringLiteralClass:
case Expr::ArraySubscriptExprClass:
case Expr::OMPArraySectionExprClass:
case Expr::MemberExprClass:
case Expr::CompoundAssignOperatorClass:
case Expr::CompoundLiteralExprClass:
case Expr::ExtVectorElementExprClass:
case Expr::DesignatedInitExprClass:
case Expr::ArrayInitLoopExprClass:
case Expr::ArrayInitIndexExprClass:
case Expr::NoInitExprClass:
case Expr::DesignatedInitUpdateExprClass:
case Expr::ImplicitValueInitExprClass:
case Expr::ParenListExprClass:
case Expr::VAArgExprClass:
case Expr::AddrLabelExprClass:
case Expr::StmtExprClass:
case Expr::CXXMemberCallExprClass:
case Expr::CUDAKernelCallExprClass:
case Expr::CXXDynamicCastExprClass:
case Expr::CXXTypeidExprClass:
case Expr::CXXUuidofExprClass:
case Expr::MSPropertyRefExprClass:
case Expr::MSPropertySubscriptExprClass:
case Expr::CXXNullPtrLiteralExprClass:
case Expr::UserDefinedLiteralClass:
case Expr::CXXThisExprClass:
case Expr::CXXThrowExprClass:
case Expr::CXXNewExprClass:
case Expr::CXXDeleteExprClass:
case Expr::CXXPseudoDestructorExprClass:
case Expr::UnresolvedLookupExprClass:
case Expr::TypoExprClass:
case Expr::DependentScopeDeclRefExprClass:
case Expr::CXXConstructExprClass:
case Expr::CXXInheritedCtorInitExprClass:
case Expr::CXXStdInitializerListExprClass:
case Expr::CXXBindTemporaryExprClass:
case Expr::ExprWithCleanupsClass:
case Expr::CXXTemporaryObjectExprClass:
case Expr::CXXUnresolvedConstructExprClass:
case Expr::CXXDependentScopeMemberExprClass:
case Expr::UnresolvedMemberExprClass:
case Expr::ObjCStringLiteralClass:
case Expr::ObjCBoxedExprClass:
case Expr::ObjCArrayLiteralClass:
case Expr::ObjCDictionaryLiteralClass:
case Expr::ObjCEncodeExprClass:
case Expr::ObjCMessageExprClass:
case Expr::ObjCSelectorExprClass:
case Expr::ObjCProtocolExprClass:
case Expr::ObjCIvarRefExprClass:
case Expr::ObjCPropertyRefExprClass:
case Expr::ObjCSubscriptRefExprClass:
case Expr::ObjCIsaExprClass:
case Expr::ObjCAvailabilityCheckExprClass:
case Expr::ShuffleVectorExprClass:
case Expr::ConvertVectorExprClass:
case Expr::BlockExprClass:
case Expr::NoStmtClass:
case Expr::OpaqueValueExprClass:
case Expr::PackExpansionExprClass:
case Expr::SubstNonTypeTemplateParmPackExprClass:
case Expr::FunctionParmPackExprClass:
case Expr::AsTypeExprClass:
case Expr::ObjCIndirectCopyRestoreExprClass:
case Expr::MaterializeTemporaryExprClass:
case Expr::PseudoObjectExprClass:
case Expr::AtomicExprClass:
case Expr::LambdaExprClass:
case Expr::CXXFoldExprClass:
case Expr::CoawaitExprClass:
case Expr::DependentCoawaitExprClass:
case Expr::CoyieldExprClass:
return ICEDiag(IK_NotICE, E->getLocStart());
case Expr::InitListExprClass: {
// C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the
// form "T x = { a };" is equivalent to "T x = a;".
// Unless we're initializing a reference, T is a scalar as it is known to be
// of integral or enumeration type.
if (E->isRValue())
if (cast<InitListExpr>(E)->getNumInits() == 1)
return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx);
return ICEDiag(IK_NotICE, E->getLocStart());
}
case Expr::SizeOfPackExprClass:
case Expr::GNUNullExprClass:
// GCC considers the GNU __null value to be an integral constant expression.
return NoDiag();
case Expr::SubstNonTypeTemplateParmExprClass:
return
CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx);
case Expr::ParenExprClass:
return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx);
case Expr::GenericSelectionExprClass:
return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx);
case Expr::IntegerLiteralClass:
case Expr::CharacterLiteralClass:
case Expr::ObjCBoolLiteralExprClass:
case Expr::CXXBoolLiteralExprClass:
case Expr::CXXScalarValueInitExprClass:
case Expr::TypeTraitExprClass:
case Expr::ArrayTypeTraitExprClass:
case Expr::ExpressionTraitExprClass:
case Expr::CXXNoexceptExprClass:
return NoDiag();
case Expr::CallExprClass:
case Expr::CXXOperatorCallExprClass: {
// C99 6.6/3 allows function calls within unevaluated subexpressions of
// constant expressions, but they can never be ICEs because an ICE cannot
// contain an operand of (pointer to) function type.
const CallExpr *CE = cast<CallExpr>(E);
if (CE->getBuiltinCallee())
return CheckEvalInICE(E, Ctx);
return ICEDiag(IK_NotICE, E->getLocStart());
}
case Expr::DeclRefExprClass: {
if (isa<EnumConstantDecl>(cast<DeclRefExpr>(E)->getDecl()))
return NoDiag();
const ValueDecl *D = dyn_cast<ValueDecl>(cast<DeclRefExpr>(E)->getDecl());
if (Ctx.getLangOpts().CPlusPlus &&
D && IsConstNonVolatile(D->getType())) {
// Parameter variables are never constants. Without this check,
// getAnyInitializer() can find a default argument, which leads
// to chaos.
if (isa<ParmVarDecl>(D))
return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation());
// C++ 7.1.5.1p2
// A variable of non-volatile const-qualified integral or enumeration
// type initialized by an ICE can be used in ICEs.
if (const VarDecl *Dcl = dyn_cast<VarDecl>(D)) {
if (!Dcl->getType()->isIntegralOrEnumerationType())
return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation());
const VarDecl *VD;
// Look for a declaration of this variable that has an initializer, and
// check whether it is an ICE.
if (Dcl->getAnyInitializer(VD) && VD->checkInitIsICE())
return NoDiag();
else
return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation());
}
}
return ICEDiag(IK_NotICE, E->getLocStart());
}
case Expr::UnaryOperatorClass: {
const UnaryOperator *Exp = cast<UnaryOperator>(E);
switch (Exp->getOpcode()) {
case UO_PostInc:
case UO_PostDec:
case UO_PreInc:
case UO_PreDec:
case UO_AddrOf:
case UO_Deref:
case UO_Coawait:
// C99 6.6/3 allows increment and decrement within unevaluated
// subexpressions of constant expressions, but they can never be ICEs
// because an ICE cannot contain an lvalue operand.
return ICEDiag(IK_NotICE, E->getLocStart());
case UO_Extension:
case UO_LNot:
case UO_Plus:
case UO_Minus:
case UO_Not:
case UO_Real:
case UO_Imag:
return CheckICE(Exp->getSubExpr(), Ctx);
}
// OffsetOf falls through here.
}
case Expr::OffsetOfExprClass: {
// Note that per C99, offsetof must be an ICE. And AFAIK, using
// EvaluateAsRValue matches the proposed gcc behavior for cases like
// "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect
// compliance: we should warn earlier for offsetof expressions with
// array subscripts that aren't ICEs, and if the array subscripts
// are ICEs, the value of the offsetof must be an integer constant.
return CheckEvalInICE(E, Ctx);
}
case Expr::UnaryExprOrTypeTraitExprClass: {
const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E);
if ((Exp->getKind() == UETT_SizeOf) &&
Exp->getTypeOfArgument()->isVariableArrayType())
return ICEDiag(IK_NotICE, E->getLocStart());
return NoDiag();
}
case Expr::BinaryOperatorClass: {
const BinaryOperator *Exp = cast<BinaryOperator>(E);
switch (Exp->getOpcode()) {
case BO_PtrMemD:
case BO_PtrMemI:
case BO_Assign:
case BO_MulAssign:
case BO_DivAssign:
case BO_RemAssign:
case BO_AddAssign:
case BO_SubAssign:
case BO_ShlAssign:
case BO_ShrAssign:
case BO_AndAssign:
case BO_XorAssign:
case BO_OrAssign:
// C99 6.6/3 allows assignments within unevaluated subexpressions of
// constant expressions, but they can never be ICEs because an ICE cannot
// contain an lvalue operand.
return ICEDiag(IK_NotICE, E->getLocStart());
case BO_Mul:
case BO_Div:
case BO_Rem:
case BO_Add:
case BO_Sub:
case BO_Shl:
case BO_Shr:
case BO_LT:
case BO_GT:
case BO_LE:
case BO_GE:
case BO_EQ:
case BO_NE:
case BO_And:
case BO_Xor:
case BO_Or:
case BO_Comma: {
ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx);
ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx);
if (Exp->getOpcode() == BO_Div ||
Exp->getOpcode() == BO_Rem) {
// EvaluateAsRValue gives an error for undefined Div/Rem, so make sure
// we don't evaluate one.
if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) {
llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx);
if (REval == 0)
return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart());
if (REval.isSigned() && REval.isAllOnesValue()) {
llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx);
if (LEval.isMinSignedValue())
return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart());
}
}
}
if (Exp->getOpcode() == BO_Comma) {
if (Ctx.getLangOpts().C99) {
// C99 6.6p3 introduces a strange edge case: comma can be in an ICE
// if it isn't evaluated.
if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE)
return ICEDiag(IK_ICEIfUnevaluated, E->getLocStart());
} else {
// In both C89 and C++, commas in ICEs are illegal.
return ICEDiag(IK_NotICE, E->getLocStart());
}
}
return Worst(LHSResult, RHSResult);
}
case BO_LAnd:
case BO_LOr: {
ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx);
ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx);
if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) {
// Rare case where the RHS has a comma "side-effect"; we need
// to actually check the condition to see whether the side
// with the comma is evaluated.
if ((Exp->getOpcode() == BO_LAnd) !=
(Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0))
return RHSResult;
return NoDiag();
}
return Worst(LHSResult, RHSResult);
}
}
}
case Expr::ImplicitCastExprClass:
case Expr::CStyleCastExprClass:
case Expr::CXXFunctionalCastExprClass:
case Expr::CXXStaticCastExprClass:
case Expr::CXXReinterpretCastExprClass:
case Expr::CXXConstCastExprClass:
case Expr::ObjCBridgedCastExprClass: {
const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr();
if (isa<ExplicitCastExpr>(E)) {
if (const FloatingLiteral *FL
= dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) {
unsigned DestWidth = Ctx.getIntWidth(E->getType());
bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType();
APSInt IgnoredVal(DestWidth, !DestSigned);
bool Ignored;
// If the value does not fit in the destination type, the behavior is
// undefined, so we are not required to treat it as a constant
// expression.
if (FL->getValue().convertToInteger(IgnoredVal,
llvm::APFloat::rmTowardZero,
&Ignored) & APFloat::opInvalidOp)
return ICEDiag(IK_NotICE, E->getLocStart());
return NoDiag();
}
}
switch (cast<CastExpr>(E)->getCastKind()) {
case CK_LValueToRValue:
case CK_AtomicToNonAtomic:
case CK_NonAtomicToAtomic:
case CK_NoOp:
case CK_IntegralToBoolean:
case CK_IntegralCast:
return CheckICE(SubExpr, Ctx);
default:
return ICEDiag(IK_NotICE, E->getLocStart());
}
}
case Expr::BinaryConditionalOperatorClass: {
const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E);
ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx);
if (CommonResult.Kind == IK_NotICE) return CommonResult;
ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx);
if (FalseResult.Kind == IK_NotICE) return FalseResult;
if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult;
if (FalseResult.Kind == IK_ICEIfUnevaluated &&
Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag();
return FalseResult;
}
case Expr::ConditionalOperatorClass: {
const ConditionalOperator *Exp = cast<ConditionalOperator>(E);
// If the condition (ignoring parens) is a __builtin_constant_p call,
// then only the true side is actually considered in an integer constant
// expression, and it is fully evaluated. This is an important GNU
// extension. See GCC PR38377 for discussion.
if (const CallExpr *CallCE
= dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts()))
if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
return CheckEvalInICE(E, Ctx);
ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx);
if (CondResult.Kind == IK_NotICE)
return CondResult;
ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx);
ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx);
if (TrueResult.Kind == IK_NotICE)
return TrueResult;
if (FalseResult.Kind == IK_NotICE)
return FalseResult;
if (CondResult.Kind == IK_ICEIfUnevaluated)
return CondResult;
if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE)
return NoDiag();
// Rare case where the diagnostics depend on which side is evaluated
// Note that if we get here, CondResult is 0, and at least one of
// TrueResult and FalseResult is non-zero.
if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0)
return FalseResult;
return TrueResult;
}
case Expr::CXXDefaultArgExprClass:
return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx);
case Expr::CXXDefaultInitExprClass:
return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx);
case Expr::ChooseExprClass: {
return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx);
}
}
llvm_unreachable("Invalid StmtClass!");
}
/// Evaluate an expression as a C++11 integral constant expression.
static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx,
const Expr *E,
llvm::APSInt *Value,
SourceLocation *Loc) {
if (!E->getType()->isIntegralOrEnumerationType()) {
if (Loc) *Loc = E->getExprLoc();
return false;
}
APValue Result;
if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc))
return false;
if (!Result.isInt()) {
if (Loc) *Loc = E->getExprLoc();
return false;
}
if (Value) *Value = Result.getInt();
return true;
}
bool Expr::isIntegerConstantExpr(const ASTContext &Ctx,
SourceLocation *Loc) const {
if (Ctx.getLangOpts().CPlusPlus11)
return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc);
ICEDiag D = CheckICE(this, Ctx);
if (D.Kind != IK_ICE) {
if (Loc) *Loc = D.Loc;
return false;
}
return true;
}
bool Expr::isIntegerConstantExpr(llvm::APSInt &Value, const ASTContext &Ctx,
SourceLocation *Loc, bool isEvaluated) const {
if (Ctx.getLangOpts().CPlusPlus11)
return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc);
if (!isIntegerConstantExpr(Ctx, Loc))
return false;
// The only possible side-effects here are due to UB discovered in the
// evaluation (for instance, INT_MAX + 1). In such a case, we are still
// required to treat the expression as an ICE, so we produce the folded
// value.
if (!EvaluateAsInt(Value, Ctx, SE_AllowSideEffects))
llvm_unreachable("ICE cannot be evaluated!");
return true;
}
bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const {
return CheckICE(this, Ctx).Kind == IK_ICE;
}
bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result,
SourceLocation *Loc) const {
// We support this checking in C++98 mode in order to diagnose compatibility
// issues.
assert(Ctx.getLangOpts().CPlusPlus);
// Build evaluation settings.
Expr::EvalStatus Status;
SmallVector<PartialDiagnosticAt, 8> Diags;
Status.Diag = &Diags;
EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
APValue Scratch;
bool IsConstExpr = ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch);
if (!Diags.empty()) {
IsConstExpr = false;
if (Loc) *Loc = Diags[0].first;
} else if (!IsConstExpr) {
// FIXME: This shouldn't happen.
if (Loc) *Loc = getExprLoc();
}
return IsConstExpr;
}
bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
const FunctionDecl *Callee,
ArrayRef<const Expr*> Args,
const Expr *This) const {
Expr::EvalStatus Status;
EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated);
LValue ThisVal;
const LValue *ThisPtr = nullptr;
if (This) {
#ifndef NDEBUG
auto *MD = dyn_cast<CXXMethodDecl>(Callee);
assert(MD && "Don't provide `this` for non-methods.");
assert(!MD->isStatic() && "Don't provide `this` for static methods.");
#endif
if (EvaluateObjectArgument(Info, This, ThisVal))
ThisPtr = &ThisVal;
if (Info.EvalStatus.HasSideEffects)
return false;
}
ArgVector ArgValues(Args.size());
for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
I != E; ++I) {
if ((*I)->isValueDependent() ||
!Evaluate(ArgValues[I - Args.begin()], Info, *I))
// If evaluation fails, throw away the argument entirely.
ArgValues[I - Args.begin()] = APValue();
if (Info.EvalStatus.HasSideEffects)
return false;
}
// Build fake call to Callee.
CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr,
ArgValues.data());
return Evaluate(Value, Info, this) && !Info.EvalStatus.HasSideEffects;
}
bool Expr::isPotentialConstantExpr(const FunctionDecl *FD,
SmallVectorImpl<
PartialDiagnosticAt> &Diags) {
// FIXME: It would be useful to check constexpr function templates, but at the
// moment the constant expression evaluator cannot cope with the non-rigorous
// ASTs which we build for dependent expressions.
if (FD->isDependentContext())
return true;
Expr::EvalStatus Status;
Status.Diag = &Diags;
EvalInfo Info(FD->getASTContext(), Status,
EvalInfo::EM_PotentialConstantExpression);
const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr;
// Fabricate an arbitrary expression on the stack and pretend that it
// is a temporary being used as the 'this' pointer.
LValue This;
ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy);
This.set(&VIE, Info.CurrentCall->Index);
ArrayRef<const Expr*> Args;
APValue Scratch;
if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) {
// Evaluate the call as a constant initializer, to allow the construction
// of objects of non-literal types.
Info.setEvaluatingDecl(This.getLValueBase(), Scratch);
HandleConstructorCall(&VIE, This, Args, CD, Info, Scratch);
} else {
SourceLocation Loc = FD->getLocation();
HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr,
Args, FD->getBody(), Info, Scratch, nullptr);
}
return Diags.empty();
}
bool Expr::isPotentialConstantExprUnevaluated(Expr *E,
const FunctionDecl *FD,
SmallVectorImpl<
PartialDiagnosticAt> &Diags) {
Expr::EvalStatus Status;
Status.Diag = &Diags;
EvalInfo Info(FD->getASTContext(), Status,
EvalInfo::EM_PotentialConstantExpressionUnevaluated);
// Fabricate a call stack frame to give the arguments a plausible cover story.
ArrayRef<const Expr*> Args;
ArgVector ArgValues(0);
bool Success = EvaluateArgs(Args, ArgValues, Info);
(void)Success;
assert(Success &&
"Failed to set up arguments for potential constant evaluation");
CallStackFrame Frame(Info, SourceLocation(), FD, nullptr, ArgValues.data());
APValue ResultScratch;
Evaluate(ResultScratch, Info, E);
return Diags.empty();
}
bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx,
unsigned Type) const {
if (!getType()->isPointerType())
return false;
Expr::EvalStatus Status;
EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
return tryEvaluateBuiltinObjectSize(this, Type, Info, Result);
}
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