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390437fc6d
llvm/lib/VMCore/ConstantFold.cpp
Reid Spencer 390437fc6d Rewrite ConstantFoldCastInstruction so that it doesn't use any of the 
ConstRules. Remove the casting rules from ConstRules and subclasses. This
cleans up ConstantFolding significantly. Passes all tests.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32671 91177308-0d34-0410-b5e6-96231b3b80d8
2006-12-19 03:15:47 +00:00

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//===- ConstantFolding.cpp - LLVM constant folder -------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements folding of constants for LLVM. This implements the
// (internal) ConstantFolding.h interface, which is used by the
// ConstantExpr::get* methods to automatically fold constants when possible.
//
// The current constant folding implementation is implemented in two pieces: the
// template-based folder for simple primitive constants like ConstantInt, and
// the special case hackery that we use to symbolically evaluate expressions
// that use ConstantExprs.
//
//===----------------------------------------------------------------------===//
#include "ConstantFolding.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/MathExtras.h"
#include <limits>
using namespace llvm;
namespace {
struct VISIBILITY_HIDDEN ConstRules {
ConstRules() {}
virtual ~ConstRules() {}
// Binary Operators...
virtual Constant *add(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *sub(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *mul(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *urem(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *srem(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *frem(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *udiv(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *sdiv(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *fdiv(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *op_and(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *op_or (const Constant *V1, const Constant *V2) const = 0;
virtual Constant *op_xor(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *shl(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *lshr(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *ashr(const Constant *V1, const Constant *V2) const = 0;
virtual Constant *lessthan(const Constant *V1, const Constant *V2) const =0;
virtual Constant *equalto(const Constant *V1, const Constant *V2) const = 0;
// ConstRules::get - Return an instance of ConstRules for the specified
// constant operands.
//
static ConstRules &get(const Constant *V1, const Constant *V2);
private:
ConstRules(const ConstRules &); // Do not implement
ConstRules &operator=(const ConstRules &); // Do not implement
};
}
//===----------------------------------------------------------------------===//
// TemplateRules Class
//===----------------------------------------------------------------------===//
//
// TemplateRules - Implement a subclass of ConstRules that provides all
// operations as noops. All other rules classes inherit from this class so
// that if functionality is needed in the future, it can simply be added here
// and to ConstRules without changing anything else...
//
// This class also provides subclasses with typesafe implementations of methods
// so that don't have to do type casting.
//
namespace {
template<class ArgType, class SubClassName>
class VISIBILITY_HIDDEN TemplateRules : public ConstRules {
//===--------------------------------------------------------------------===//
// Redirecting functions that cast to the appropriate types
//===--------------------------------------------------------------------===//
virtual Constant *add(const Constant *V1, const Constant *V2) const {
return SubClassName::Add((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *sub(const Constant *V1, const Constant *V2) const {
return SubClassName::Sub((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *mul(const Constant *V1, const Constant *V2) const {
return SubClassName::Mul((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *udiv(const Constant *V1, const Constant *V2) const {
return SubClassName::UDiv((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *sdiv(const Constant *V1, const Constant *V2) const {
return SubClassName::SDiv((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *fdiv(const Constant *V1, const Constant *V2) const {
return SubClassName::FDiv((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *urem(const Constant *V1, const Constant *V2) const {
return SubClassName::URem((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *srem(const Constant *V1, const Constant *V2) const {
return SubClassName::SRem((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *frem(const Constant *V1, const Constant *V2) const {
return SubClassName::FRem((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *op_and(const Constant *V1, const Constant *V2) const {
return SubClassName::And((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *op_or(const Constant *V1, const Constant *V2) const {
return SubClassName::Or((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *op_xor(const Constant *V1, const Constant *V2) const {
return SubClassName::Xor((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *shl(const Constant *V1, const Constant *V2) const {
return SubClassName::Shl((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *lshr(const Constant *V1, const Constant *V2) const {
return SubClassName::LShr((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *ashr(const Constant *V1, const Constant *V2) const {
return SubClassName::AShr((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *lessthan(const Constant *V1, const Constant *V2) const {
return SubClassName::LessThan((const ArgType *)V1, (const ArgType *)V2);
}
virtual Constant *equalto(const Constant *V1, const Constant *V2) const {
return SubClassName::EqualTo((const ArgType *)V1, (const ArgType *)V2);
}
//===--------------------------------------------------------------------===//
// Default "noop" implementations
//===--------------------------------------------------------------------===//
static Constant *Add (const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *Sub (const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *Mul (const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *SDiv(const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *UDiv(const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *FDiv(const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *URem(const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *SRem(const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *FRem(const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *And (const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *Or (const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *Xor (const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *Shl (const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *LShr(const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *AShr(const ArgType *V1, const ArgType *V2) { return 0; }
static Constant *LessThan(const ArgType *V1, const ArgType *V2) {
return 0;
}
static Constant *EqualTo(const ArgType *V1, const ArgType *V2) {
return 0;
}
public:
virtual ~TemplateRules() {}
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// EmptyRules Class
//===----------------------------------------------------------------------===//
//
// EmptyRules provides a concrete base class of ConstRules that does nothing
//
namespace {
struct VISIBILITY_HIDDEN EmptyRules
: public TemplateRules<Constant, EmptyRules> {
static Constant *EqualTo(const Constant *V1, const Constant *V2) {
if (V1 == V2) return ConstantBool::getTrue();
return 0;
}
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// BoolRules Class
//===----------------------------------------------------------------------===//
//
// BoolRules provides a concrete base class of ConstRules for the 'bool' type.
//
namespace {
struct VISIBILITY_HIDDEN BoolRules
: public TemplateRules<ConstantBool, BoolRules> {
static Constant *LessThan(const ConstantBool *V1, const ConstantBool *V2) {
return ConstantBool::get(V1->getValue() < V2->getValue());
}
static Constant *EqualTo(const Constant *V1, const Constant *V2) {
return ConstantBool::get(V1 == V2);
}
static Constant *And(const ConstantBool *V1, const ConstantBool *V2) {
return ConstantBool::get(V1->getValue() & V2->getValue());
}
static Constant *Or(const ConstantBool *V1, const ConstantBool *V2) {
return ConstantBool::get(V1->getValue() | V2->getValue());
}
static Constant *Xor(const ConstantBool *V1, const ConstantBool *V2) {
return ConstantBool::get(V1->getValue() ^ V2->getValue());
}
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// NullPointerRules Class
//===----------------------------------------------------------------------===//
//
// NullPointerRules provides a concrete base class of ConstRules for null
// pointers.
//
namespace {
struct VISIBILITY_HIDDEN NullPointerRules
: public TemplateRules<ConstantPointerNull, NullPointerRules> {
static Constant *EqualTo(const Constant *V1, const Constant *V2) {
return ConstantBool::getTrue(); // Null pointers are always equal
}
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// ConstantPackedRules Class
//===----------------------------------------------------------------------===//
/// DoVectorOp - Given two packed constants and a function pointer, apply the
/// function pointer to each element pair, producing a new ConstantPacked
/// constant.
static Constant *EvalVectorOp(const ConstantPacked *V1,
const ConstantPacked *V2,
Constant *(*FP)(Constant*, Constant*)) {
std::vector<Constant*> Res;
for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i)
Res.push_back(FP(const_cast<Constant*>(V1->getOperand(i)),
const_cast<Constant*>(V2->getOperand(i))));
return ConstantPacked::get(Res);
}
/// PackedTypeRules provides a concrete base class of ConstRules for
/// ConstantPacked operands.
///
namespace {
struct VISIBILITY_HIDDEN ConstantPackedRules
: public TemplateRules<ConstantPacked, ConstantPackedRules> {
static Constant *Add(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getAdd);
}
static Constant *Sub(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getSub);
}
static Constant *Mul(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getMul);
}
static Constant *UDiv(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getUDiv);
}
static Constant *SDiv(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getSDiv);
}
static Constant *FDiv(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getFDiv);
}
static Constant *URem(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getURem);
}
static Constant *SRem(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getSRem);
}
static Constant *FRem(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getFRem);
}
static Constant *And(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getAnd);
}
static Constant *Or (const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getOr);
}
static Constant *Xor(const ConstantPacked *V1, const ConstantPacked *V2) {
return EvalVectorOp(V1, V2, ConstantExpr::getXor);
}
static Constant *LessThan(const ConstantPacked *V1, const ConstantPacked *V2){
return 0;
}
static Constant *EqualTo(const ConstantPacked *V1, const ConstantPacked *V2) {
for (unsigned i = 0, e = V1->getNumOperands(); i != e; ++i) {
Constant *C =
ConstantExpr::getSetEQ(const_cast<Constant*>(V1->getOperand(i)),
const_cast<Constant*>(V2->getOperand(i)));
if (ConstantBool *CB = dyn_cast<ConstantBool>(C))
return CB;
}
// Otherwise, could not decide from any element pairs.
return 0;
}
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// GeneralPackedRules Class
//===----------------------------------------------------------------------===//
/// GeneralPackedRules provides a concrete base class of ConstRules for
/// PackedType operands, where both operands are not ConstantPacked. The usual
/// cause for this is that one operand is a ConstantAggregateZero.
///
namespace {
struct VISIBILITY_HIDDEN GeneralPackedRules
: public TemplateRules<Constant, GeneralPackedRules> {
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// DirectIntRules Class
//===----------------------------------------------------------------------===//
//
// DirectIntRules provides implementations of functions that are valid on
// integer types, but not all types in general.
//
namespace {
template <class BuiltinType, Type **Ty>
struct VISIBILITY_HIDDEN DirectIntRules
: public TemplateRules<ConstantInt, DirectIntRules<BuiltinType, Ty> > {
static Constant *Add(const ConstantInt *V1, const ConstantInt *V2) {
BuiltinType R = (BuiltinType)V1->getZExtValue() +
(BuiltinType)V2->getZExtValue();
return ConstantInt::get(*Ty, R);
}
static Constant *Sub(const ConstantInt *V1, const ConstantInt *V2) {
BuiltinType R = (BuiltinType)V1->getZExtValue() -
(BuiltinType)V2->getZExtValue();
return ConstantInt::get(*Ty, R);
}
static Constant *Mul(const ConstantInt *V1, const ConstantInt *V2) {
BuiltinType R = (BuiltinType)V1->getZExtValue() *
(BuiltinType)V2->getZExtValue();
return ConstantInt::get(*Ty, R);
}
static Constant *LessThan(const ConstantInt *V1, const ConstantInt *V2) {
bool R = (BuiltinType)V1->getZExtValue() < (BuiltinType)V2->getZExtValue();
return ConstantBool::get(R);
}
static Constant *EqualTo(const ConstantInt *V1, const ConstantInt *V2) {
bool R = (BuiltinType)V1->getZExtValue() == (BuiltinType)V2->getZExtValue();
return ConstantBool::get(R);
}
static Constant *UDiv(const ConstantInt *V1, const ConstantInt *V2) {
if (V2->isNullValue()) // X / 0
return 0;
BuiltinType R = (BuiltinType)(V1->getZExtValue() / V2->getZExtValue());
return ConstantInt::get(*Ty, R);
}
static Constant *SDiv(const ConstantInt *V1, const ConstantInt *V2) {
if (V2->isNullValue()) // X / 0
return 0;
if (V2->isAllOnesValue() && // MIN_INT / -1
(BuiltinType)V1->getSExtValue() == -(BuiltinType)V1->getSExtValue())
return 0;
BuiltinType R = (BuiltinType)(V1->getSExtValue() / V2->getSExtValue());
return ConstantInt::get(*Ty, R);
}
static Constant *URem(const ConstantInt *V1,
const ConstantInt *V2) {
if (V2->isNullValue()) return 0; // X / 0
BuiltinType R = (BuiltinType)(V1->getZExtValue() % V2->getZExtValue());
return ConstantInt::get(*Ty, R);
}
static Constant *SRem(const ConstantInt *V1,
const ConstantInt *V2) {
if (V2->isNullValue()) return 0; // X % 0
if (V2->isAllOnesValue() && // MIN_INT % -1
(BuiltinType)V1->getSExtValue() == -(BuiltinType)V1->getSExtValue())
return 0;
BuiltinType R = (BuiltinType)(V1->getSExtValue() % V2->getSExtValue());
return ConstantInt::get(*Ty, R);
}
static Constant *And(const ConstantInt *V1, const ConstantInt *V2) {
BuiltinType R =
(BuiltinType)V1->getZExtValue() & (BuiltinType)V2->getZExtValue();
return ConstantInt::get(*Ty, R);
}
static Constant *Or(const ConstantInt *V1, const ConstantInt *V2) {
BuiltinType R =
(BuiltinType)V1->getZExtValue() | (BuiltinType)V2->getZExtValue();
return ConstantInt::get(*Ty, R);
}
static Constant *Xor(const ConstantInt *V1, const ConstantInt *V2) {
BuiltinType R =
(BuiltinType)V1->getZExtValue() ^ (BuiltinType)V2->getZExtValue();
return ConstantInt::get(*Ty, R);
}
static Constant *Shl(const ConstantInt *V1, const ConstantInt *V2) {
BuiltinType R =
(BuiltinType)V1->getZExtValue() << (BuiltinType)V2->getZExtValue();
return ConstantInt::get(*Ty, R);
}
static Constant *LShr(const ConstantInt *V1, const ConstantInt *V2) {
BuiltinType R = BuiltinType(V1->getZExtValue() >> V2->getZExtValue());
return ConstantInt::get(*Ty, R);
}
static Constant *AShr(const ConstantInt *V1, const ConstantInt *V2) {
BuiltinType R = BuiltinType(V1->getSExtValue() >> V2->getZExtValue());
return ConstantInt::get(*Ty, R);
}
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// DirectFPRules Class
//===----------------------------------------------------------------------===//
//
/// DirectFPRules provides implementations of functions that are valid on
/// floating point types, but not all types in general.
///
namespace {
template <class BuiltinType, Type **Ty>
struct VISIBILITY_HIDDEN DirectFPRules
: public TemplateRules<ConstantFP, DirectFPRules<BuiltinType, Ty> > {
static Constant *Add(const ConstantFP *V1, const ConstantFP *V2) {
BuiltinType R = (BuiltinType)V1->getValue() +
(BuiltinType)V2->getValue();
return ConstantFP::get(*Ty, R);
}
static Constant *Sub(const ConstantFP *V1, const ConstantFP *V2) {
BuiltinType R = (BuiltinType)V1->getValue() - (BuiltinType)V2->getValue();
return ConstantFP::get(*Ty, R);
}
static Constant *Mul(const ConstantFP *V1, const ConstantFP *V2) {
BuiltinType R = (BuiltinType)V1->getValue() * (BuiltinType)V2->getValue();
return ConstantFP::get(*Ty, R);
}
static Constant *LessThan(const ConstantFP *V1, const ConstantFP *V2) {
bool R = (BuiltinType)V1->getValue() < (BuiltinType)V2->getValue();
return ConstantBool::get(R);
}
static Constant *EqualTo(const ConstantFP *V1, const ConstantFP *V2) {
bool R = (BuiltinType)V1->getValue() == (BuiltinType)V2->getValue();
return ConstantBool::get(R);
}
static Constant *FRem(const ConstantFP *V1, const ConstantFP *V2) {
if (V2->isNullValue()) return 0;
BuiltinType Result = std::fmod((BuiltinType)V1->getValue(),
(BuiltinType)V2->getValue());
return ConstantFP::get(*Ty, Result);
}
static Constant *FDiv(const ConstantFP *V1, const ConstantFP *V2) {
BuiltinType inf = std::numeric_limits<BuiltinType>::infinity();
if (V2->isExactlyValue(0.0)) return ConstantFP::get(*Ty, inf);
if (V2->isExactlyValue(-0.0)) return ConstantFP::get(*Ty, -inf);
BuiltinType R = (BuiltinType)V1->getValue() / (BuiltinType)V2->getValue();
return ConstantFP::get(*Ty, R);
}
};
} // end anonymous namespace
static ManagedStatic<EmptyRules> EmptyR;
static ManagedStatic<BoolRules> BoolR;
static ManagedStatic<NullPointerRules> NullPointerR;
static ManagedStatic<ConstantPackedRules> ConstantPackedR;
static ManagedStatic<GeneralPackedRules> GeneralPackedR;
static ManagedStatic<DirectIntRules<signed char , &Type::SByteTy> > SByteR;
static ManagedStatic<DirectIntRules<unsigned char , &Type::UByteTy> > UByteR;
static ManagedStatic<DirectIntRules<signed short , &Type::ShortTy> > ShortR;
static ManagedStatic<DirectIntRules<unsigned short, &Type::UShortTy> > UShortR;
static ManagedStatic<DirectIntRules<signed int , &Type::IntTy> > IntR;
static ManagedStatic<DirectIntRules<unsigned int , &Type::UIntTy> > UIntR;
static ManagedStatic<DirectIntRules<int64_t , &Type::LongTy> > LongR;
static ManagedStatic<DirectIntRules<uint64_t , &Type::ULongTy> > ULongR;
static ManagedStatic<DirectFPRules <float , &Type::FloatTy> > FloatR;
static ManagedStatic<DirectFPRules <double , &Type::DoubleTy> > DoubleR;
/// ConstRules::get - This method returns the constant rules implementation that
/// implements the semantics of the two specified constants.
ConstRules &ConstRules::get(const Constant *V1, const Constant *V2) {
if (isa<ConstantExpr>(V1) || isa<ConstantExpr>(V2) ||
isa<GlobalValue>(V1) || isa<GlobalValue>(V2) ||
isa<UndefValue>(V1) || isa<UndefValue>(V2))
return *EmptyR;
switch (V1->getType()->getTypeID()) {
default: assert(0 && "Unknown value type for constant folding!");
case Type::BoolTyID: return *BoolR;
case Type::PointerTyID: return *NullPointerR;
case Type::SByteTyID: return *SByteR;
case Type::UByteTyID: return *UByteR;
case Type::ShortTyID: return *ShortR;
case Type::UShortTyID: return *UShortR;
case Type::IntTyID: return *IntR;
case Type::UIntTyID: return *UIntR;
case Type::LongTyID: return *LongR;
case Type::ULongTyID: return *ULongR;
case Type::FloatTyID: return *FloatR;
case Type::DoubleTyID: return *DoubleR;
case Type::PackedTyID:
if (isa<ConstantPacked>(V1) && isa<ConstantPacked>(V2))
return *ConstantPackedR;
return *GeneralPackedR; // Constant folding rules for ConstantAggregateZero.
}
}
//===----------------------------------------------------------------------===//
// ConstantFold*Instruction Implementations
//===----------------------------------------------------------------------===//
/// CastConstantPacked - Convert the specified ConstantPacked node to the
/// specified packed type. At this point, we know that the elements of the
/// input packed constant are all simple integer or FP values.
static Constant *CastConstantPacked(ConstantPacked *CP,
const PackedType *DstTy) {
unsigned SrcNumElts = CP->getType()->getNumElements();
unsigned DstNumElts = DstTy->getNumElements();
const Type *SrcEltTy = CP->getType()->getElementType();
const Type *DstEltTy = DstTy->getElementType();
// If both vectors have the same number of elements (thus, the elements
// are the same size), perform the conversion now.
if (SrcNumElts == DstNumElts) {
std::vector<Constant*> Result;
// If the src and dest elements are both integers, or both floats, we can
// just BitCast each element because the elements are the same size.
if ((SrcEltTy->isIntegral() && DstEltTy->isIntegral()) ||
(SrcEltTy->isFloatingPoint() && DstEltTy->isFloatingPoint())) {
for (unsigned i = 0; i != SrcNumElts; ++i)
Result.push_back(
ConstantExpr::getBitCast(CP->getOperand(i), DstEltTy));
return ConstantPacked::get(Result);
}
// If this is an int-to-fp cast ..
if (SrcEltTy->isIntegral()) {
// Ensure that it is int-to-fp cast
assert(DstEltTy->isFloatingPoint());
if (DstEltTy->getTypeID() == Type::DoubleTyID) {
for (unsigned i = 0; i != SrcNumElts; ++i) {
double V =
BitsToDouble(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
Result.push_back(ConstantFP::get(Type::DoubleTy, V));
}
return ConstantPacked::get(Result);
}
assert(DstEltTy == Type::FloatTy && "Unknown fp type!");
for (unsigned i = 0; i != SrcNumElts; ++i) {
float V =
BitsToFloat(cast<ConstantInt>(CP->getOperand(i))->getZExtValue());
Result.push_back(ConstantFP::get(Type::FloatTy, V));
}
return ConstantPacked::get(Result);
}
// Otherwise, this is an fp-to-int cast.
assert(SrcEltTy->isFloatingPoint() && DstEltTy->isIntegral());
if (SrcEltTy->getTypeID() == Type::DoubleTyID) {
for (unsigned i = 0; i != SrcNumElts; ++i) {
uint64_t V =
DoubleToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
Constant *C = ConstantInt::get(Type::ULongTy, V);
Result.push_back(ConstantExpr::getBitCast(C, DstEltTy ));
}
return ConstantPacked::get(Result);
}
assert(SrcEltTy->getTypeID() == Type::FloatTyID);
for (unsigned i = 0; i != SrcNumElts; ++i) {
uint32_t V = FloatToBits(cast<ConstantFP>(CP->getOperand(i))->getValue());
Constant *C = ConstantInt::get(Type::UIntTy, V);
Result.push_back(ConstantExpr::getBitCast(C, DstEltTy));
}
return ConstantPacked::get(Result);
}
// Otherwise, this is a cast that changes element count and size. Handle
// casts which shrink the elements here.
// FIXME: We need to know endianness to do this!
return 0;
}
/// This function determines which opcode to use to fold two constant cast
/// expressions together. It uses CastInst::isEliminableCastPair to determine
/// the opcode. Consequently its just a wrapper around that function.
/// @Determine if it is valid to fold a cast of a cast
static unsigned
foldConstantCastPair(
unsigned opc, ///< opcode of the second cast constant expression
const ConstantExpr*Op, ///< the first cast constant expression
const Type *DstTy ///< desintation type of the first cast
) {
assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
assert(CastInst::isCast(opc) && "Invalid cast opcode");
// The the types and opcodes for the two Cast constant expressions
const Type *SrcTy = Op->getOperand(0)->getType();
const Type *MidTy = Op->getType();
Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
Instruction::CastOps secondOp = Instruction::CastOps(opc);
// Let CastInst::isEliminableCastPair do the heavy lifting.
return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
Type::ULongTy);
}
Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
const Type *DestTy) {
const Type *SrcTy = V->getType();
if (isa<UndefValue>(V))
return UndefValue::get(DestTy);
// If the cast operand is a constant expression, there's a few things we can
// do to try to simplify it.
if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->isCast()) {
// Try hard to fold cast of cast because they are often eliminable.
if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy);
} else if (CE->getOpcode() == Instruction::GetElementPtr) {
// If all of the indexes in the GEP are null values, there is no pointer
// adjustment going on. We might as well cast the source pointer.
bool isAllNull = true;
for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
if (!CE->getOperand(i)->isNullValue()) {
isAllNull = false;
break;
}
if (isAllNull)
// This is casting one pointer type to another, always BitCast
return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy);
}
}
// We actually have to do a cast now. Perform the cast according to the
// opcode specified.
switch (opc) {
case Instruction::FPTrunc:
case Instruction::FPExt:
return ConstantFP::get(DestTy, cast<ConstantFP>(V)->getValue());
case Instruction::FPToUI: {
double dVal = cast<ConstantFP>(V)->getValue();
uint64_t iVal = (uint64_t) dVal;
return ConstantIntegral::get(DestTy, iVal);
}
case Instruction::FPToSI: {
double dVal = cast<ConstantFP>(V)->getValue();
int64_t iVal = (int64_t) dVal;
return ConstantIntegral::get(DestTy, iVal);
}
case Instruction::IntToPtr: //always treated as unsigned
if (V->isNullValue()) // Is it a FP or Integral null value?
return ConstantPointerNull::get(cast<PointerType>(DestTy));
return 0; // Other pointer types cannot be casted
case Instruction::PtrToInt: // always treated as unsigned
if (V->isNullValue())
return ConstantIntegral::get(DestTy, 0);
return 0; // Other pointer types cannot be casted
case Instruction::UIToFP: {
// First, extract the unsigned integer value
uint64_t Val;
if (isa<ConstantInt>(V))
Val = cast<ConstantIntegral>(V)->getZExtValue();
else if (const ConstantBool *CB = dyn_cast<ConstantBool>(V))
Val = CB->getValue() ? 1 : 0;
// Now generate the equivalent floating point value
double dVal = (double) Val;
return ConstantFP::get(DestTy, dVal);
}
case Instruction::SIToFP: {
// First, extract the signed integer value
int64_t Val;
if (isa<ConstantInt>(V))
Val = cast<ConstantIntegral>(V)->getSExtValue();
else if (const ConstantBool *CB = dyn_cast<ConstantBool>(V))
Val = CB->getValue() ? -1 : 0;
// Now generate the equivalent floating point value
double dVal = (double) Val;
return ConstantFP::get(DestTy, dVal);
}
case Instruction::ZExt:
// Handle trunc directly here if it is a ConstantIntegral.
if (isa<ConstantInt>(V))
return ConstantInt::get(DestTy, cast<ConstantInt>(V)->getZExtValue());
else if (const ConstantBool *CB = dyn_cast<ConstantBool>(V))
return ConstantInt::get(DestTy, CB->getValue() ? 1 : 0);
return 0;
case Instruction::SExt:
// A SExt always produces a signed value so we need to cast the value
// now before we try to cast it to the destiniation type.
if (isa<ConstantInt>(V))
return ConstantInt::get(DestTy, cast<ConstantInt>(V)->getSExtValue());
else if (const ConstantBool *CB = dyn_cast<ConstantBool>(V))
return ConstantInt::get(DestTy, CB->getValue() ? -1 : 0);
return 0;
case Instruction::Trunc:
// We just handle trunc directly here. The code below doesn't work for
// trunc to bool.
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V))
return ConstantIntegral::get(DestTy, CI->getZExtValue());
return 0;
case Instruction::BitCast:
if (SrcTy == DestTy)
return (Constant*)V; // no-op cast
// Check to see if we are casting a pointer to an aggregate to a pointer to
// the first element. If so, return the appropriate GEP instruction.
if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy)) {
std::vector<Value*> IdxList;
IdxList.push_back(Constant::getNullValue(Type::IntTy));
const Type *ElTy = PTy->getElementType();
while (ElTy != DPTy->getElementType()) {
if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
if (STy->getNumElements() == 0) break;
ElTy = STy->getElementType(0);
IdxList.push_back(Constant::getNullValue(Type::UIntTy));
} else if (const SequentialType *STy =
dyn_cast<SequentialType>(ElTy)) {
if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
ElTy = STy->getElementType();
IdxList.push_back(IdxList[0]);
} else {
break;
}
}
if (ElTy == DPTy->getElementType())
return ConstantExpr::getGetElementPtr(
const_cast<Constant*>(V),IdxList);
}
// Handle casts from one packed constant to another. We know that the src
// and dest type have the same size (otherwise its an illegal cast).
if (const PackedType *DestPTy = dyn_cast<PackedType>(DestTy)) {
if (const PackedType *SrcTy = dyn_cast<PackedType>(V->getType())) {
assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
"Not cast between same sized vectors!");
// First, check for null and undef
if (isa<ConstantAggregateZero>(V))
return Constant::getNullValue(DestTy);
if (isa<UndefValue>(V))
return UndefValue::get(DestTy);
if (const ConstantPacked *CP = dyn_cast<ConstantPacked>(V)) {
// This is a cast from a ConstantPacked of one type to a
// ConstantPacked of another type. Check to see if all elements of
// the input are simple.
bool AllSimpleConstants = true;
for (unsigned i = 0, e = CP->getNumOperands(); i != e; ++i) {
if (!isa<ConstantInt>(CP->getOperand(i)) &&
!isa<ConstantFP>(CP->getOperand(i))) {
AllSimpleConstants = false;
break;
}
}
// If all of the elements are simple constants, we can fold this.
if (AllSimpleConstants)
return CastConstantPacked(const_cast<ConstantPacked*>(CP), DestPTy);
}
}
}
// Finally, implement bitcast folding now. The code below doesn't handle
// bitcast right.
if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
return ConstantPointerNull::get(cast<PointerType>(DestTy));
// Handle integral constant input.
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
// Integral -> Integral, must be changing sign.
if (DestTy->isIntegral())
return ConstantInt::get(DestTy, CI->getZExtValue());
if (DestTy->isFloatingPoint()) {
if (DestTy == Type::FloatTy)
return ConstantFP::get(DestTy, BitsToFloat(CI->getZExtValue()));
assert(DestTy == Type::DoubleTy && "Unknown FP type!");
return ConstantFP::get(DestTy, BitsToDouble(CI->getZExtValue()));
}
// Otherwise, can't fold this (packed?)
return 0;
}
// Handle ConstantFP input.
if (const ConstantFP *FP = dyn_cast<ConstantFP>(V)) {
// FP -> Integral.
if (DestTy->isIntegral()) {
if (DestTy == Type::IntTy || DestTy == Type::UIntTy)
return ConstantInt::get(DestTy, FloatToBits(FP->getValue()));
assert((DestTy == Type::LongTy || DestTy == Type::ULongTy)
&& "Incorrect integer type for bitcast!");
return ConstantInt::get(DestTy, DoubleToBits(FP->getValue()));
}
}
return 0;
default:
assert(!"Invalid CE CastInst opcode");
break;
}
assert(0 && "Failed to cast constant expression");
return 0;
}
Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
const Constant *V1,
const Constant *V2) {
if (const ConstantBool *CB = dyn_cast<ConstantBool>(Cond))
return const_cast<Constant*>(CB->getValue() ? V1 : V2);
if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
if (V1 == V2) return const_cast<Constant*>(V1);
return 0;
}
Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
const Constant *Idx) {
if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
return UndefValue::get(cast<PackedType>(Val->getType())->getElementType());
if (Val->isNullValue()) // ee(zero, x) -> zero
return Constant::getNullValue(
cast<PackedType>(Val->getType())->getElementType());
if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
return const_cast<Constant*>(CVal->getOperand(CIdx->getZExtValue()));
} else if (isa<UndefValue>(Idx)) {
// ee({w,x,y,z}, undef) -> w (an arbitrary value).
return const_cast<Constant*>(CVal->getOperand(0));
}
}
return 0;
}
Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
const Constant *Elt,
const Constant *Idx) {
const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
if (!CIdx) return 0;
uint64_t idxVal = CIdx->getZExtValue();
if (isa<UndefValue>(Val)) {
// Insertion of scalar constant into packed undef
// Optimize away insertion of undef
if (isa<UndefValue>(Elt))
return const_cast<Constant*>(Val);
// Otherwise break the aggregate undef into multiple undefs and do
// the insertion
unsigned numOps =
cast<PackedType>(Val->getType())->getNumElements();
std::vector<Constant*> Ops;
Ops.reserve(numOps);
for (unsigned i = 0; i < numOps; ++i) {
const Constant *Op =
(i == idxVal) ? Elt : UndefValue::get(Elt->getType());
Ops.push_back(const_cast<Constant*>(Op));
}
return ConstantPacked::get(Ops);
}
if (isa<ConstantAggregateZero>(Val)) {
// Insertion of scalar constant into packed aggregate zero
// Optimize away insertion of zero
if (Elt->isNullValue())
return const_cast<Constant*>(Val);
// Otherwise break the aggregate zero into multiple zeros and do
// the insertion
unsigned numOps =
cast<PackedType>(Val->getType())->getNumElements();
std::vector<Constant*> Ops;
Ops.reserve(numOps);
for (unsigned i = 0; i < numOps; ++i) {
const Constant *Op =
(i == idxVal) ? Elt : Constant::getNullValue(Elt->getType());
Ops.push_back(const_cast<Constant*>(Op));
}
return ConstantPacked::get(Ops);
}
if (const ConstantPacked *CVal = dyn_cast<ConstantPacked>(Val)) {
// Insertion of scalar constant into packed constant
std::vector<Constant*> Ops;
Ops.reserve(CVal->getNumOperands());
for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
const Constant *Op =
(i == idxVal) ? Elt : cast<Constant>(CVal->getOperand(i));
Ops.push_back(const_cast<Constant*>(Op));
}
return ConstantPacked::get(Ops);
}
return 0;
}
Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
const Constant *V2,
const Constant *Mask) {
// TODO:
return 0;
}
/// isZeroSizedType - This type is zero sized if its an array or structure of
/// zero sized types. The only leaf zero sized type is an empty structure.
static bool isMaybeZeroSizedType(const Type *Ty) {
if (isa<OpaqueType>(Ty)) return true; // Can't say.
if (const StructType *STy = dyn_cast<StructType>(Ty)) {
// If all of elements have zero size, this does too.
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
return true;
} else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
return isMaybeZeroSizedType(ATy->getElementType());
}
return false;
}
/// IdxCompare - Compare the two constants as though they were getelementptr
/// indices. This allows coersion of the types to be the same thing.
///
/// If the two constants are the "same" (after coersion), return 0. If the
/// first is less than the second, return -1, if the second is less than the
/// first, return 1. If the constants are not integral, return -2.
///
static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
if (C1 == C2) return 0;
// Ok, we found a different index. Are either of the operands ConstantExprs?
// If so, we can't do anything with them.
if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
return -2; // don't know!
// Ok, we have two differing integer indices. Sign extend them to be the same
// type. Long is always big enough, so we use it.
if (C1->getType() != Type::LongTy && C1->getType() != Type::ULongTy)
C1 = ConstantExpr::getSExt(C1, Type::LongTy);
else
C1 = ConstantExpr::getBitCast(C1, Type::LongTy);
if (C2->getType() != Type::LongTy && C1->getType() != Type::ULongTy)
C2 = ConstantExpr::getSExt(C2, Type::LongTy);
else
C2 = ConstantExpr::getBitCast(C2, Type::LongTy);
if (C1 == C2) return 0; // Are they just differing types?
// If the type being indexed over is really just a zero sized type, there is
// no pointer difference being made here.
if (isMaybeZeroSizedType(ElTy))
return -2; // dunno.
// If they are really different, now that they are the same type, then we
// found a difference!
if (cast<ConstantInt>(C1)->getSExtValue() <
cast<ConstantInt>(C2)->getSExtValue())
return -1;
else
return 1;
}
/// evaluateRelation - This function determines if there is anything we can
/// decide about the two constants provided. This doesn't need to handle simple
/// things like integer comparisons, but should instead handle ConstantExprs
/// and GlobalValues. If we can determine that the two constants have a
/// particular relation to each other, we should return the corresponding SetCC
/// code, otherwise return Instruction::BinaryOpsEnd.
///
/// To simplify this code we canonicalize the relation so that the first
/// operand is always the most "complex" of the two. We consider simple
/// constants (like ConstantInt) to be the simplest, followed by
/// GlobalValues, followed by ConstantExpr's (the most complex).
///
static Instruction::BinaryOps evaluateRelation(Constant *V1, Constant *V2) {
assert(V1->getType() == V2->getType() &&
"Cannot compare different types of values!");
if (V1 == V2) return Instruction::SetEQ;
if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
// We distilled this down to a simple case, use the standard constant
// folder.
ConstantBool *R = dyn_cast<ConstantBool>(ConstantExpr::getSetEQ(V1, V2));
if (R && R->getValue()) return Instruction::SetEQ;
R = dyn_cast<ConstantBool>(ConstantExpr::getSetLT(V1, V2));
if (R && R->getValue()) return Instruction::SetLT;
R = dyn_cast<ConstantBool>(ConstantExpr::getSetGT(V1, V2));
if (R && R->getValue()) return Instruction::SetGT;
// If we couldn't figure it out, bail.
return Instruction::BinaryOpsEnd;
}
// If the first operand is simple, swap operands.
Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
if (SwappedRelation != Instruction::BinaryOpsEnd)
return SetCondInst::getSwappedCondition(SwappedRelation);
} else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
if (isa<ConstantExpr>(V2)) { // Swap as necessary.
Instruction::BinaryOps SwappedRelation = evaluateRelation(V2, V1);
if (SwappedRelation != Instruction::BinaryOpsEnd)
return SetCondInst::getSwappedCondition(SwappedRelation);
else
return Instruction::BinaryOpsEnd;
}
// Now we know that the RHS is a GlobalValue or simple constant,
// which (since the types must match) means that it's a ConstantPointerNull.
if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
return Instruction::SetNE;
} else {
// GlobalVals can never be null.
assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
if (!CPR1->hasExternalWeakLinkage())
return Instruction::SetNE;
}
} else {
// Ok, the LHS is known to be a constantexpr. The RHS can be any of a
// constantexpr, a CPR, or a simple constant.
ConstantExpr *CE1 = cast<ConstantExpr>(V1);
Constant *CE1Op0 = CE1->getOperand(0);
switch (CE1->getOpcode()) {
case Instruction::Trunc:
case Instruction::FPTrunc:
case Instruction::FPExt:
case Instruction::FPToUI:
case Instruction::FPToSI:
break; // We don't do anything with floating point.
case Instruction::ZExt:
case Instruction::SExt:
case Instruction::UIToFP:
case Instruction::SIToFP:
case Instruction::PtrToInt:
case Instruction::IntToPtr:
case Instruction::BitCast:
// If the cast is not actually changing bits, and the second operand is a
// null pointer, do the comparison with the pre-casted value.
if (V2->isNullValue() &&
(isa<PointerType>(CE1->getType()) || CE1->getType()->isIntegral()))
return evaluateRelation(CE1Op0,
Constant::getNullValue(CE1Op0->getType()));
// If the dest type is a pointer type, and the RHS is a constantexpr cast
// from the same type as the src of the LHS, evaluate the inputs. This is
// important for things like "seteq (cast 4 to int*), (cast 5 to int*)",
// which happens a lot in compilers with tagged integers.
if (ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
if (isa<PointerType>(CE1->getType()) && CE2->isCast() &&
CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
CE1->getOperand(0)->getType()->isIntegral()) {
return evaluateRelation(CE1->getOperand(0), CE2->getOperand(0));
}
break;
case Instruction::GetElementPtr:
// Ok, since this is a getelementptr, we know that the constant has a
// pointer type. Check the various cases.
if (isa<ConstantPointerNull>(V2)) {
// If we are comparing a GEP to a null pointer, check to see if the base
// of the GEP equals the null pointer.
if (GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
if (GV->hasExternalWeakLinkage())
// Weak linkage GVals could be zero or not. We're comparing that
// to null pointer so its greater-or-equal
return Instruction::SetGE;
else
// If its not weak linkage, the GVal must have a non-zero address
// so the result is greater-than
return Instruction::SetGT;
} else if (isa<ConstantPointerNull>(CE1Op0)) {
// If we are indexing from a null pointer, check to see if we have any
// non-zero indices.
for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
if (!CE1->getOperand(i)->isNullValue())
// Offsetting from null, must not be equal.
return Instruction::SetGT;
// Only zero indexes from null, must still be zero.
return Instruction::SetEQ;
}
// Otherwise, we can't really say if the first operand is null or not.
} else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
if (isa<ConstantPointerNull>(CE1Op0)) {
if (CPR2->hasExternalWeakLinkage())
// Weak linkage GVals could be zero or not. We're comparing it to
// a null pointer, so its less-or-equal
return Instruction::SetLE;
else
// If its not weak linkage, the GVal must have a non-zero address
// so the result is less-than
return Instruction::SetLT;
} else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
if (CPR1 == CPR2) {
// If this is a getelementptr of the same global, then it must be
// different. Because the types must match, the getelementptr could
// only have at most one index, and because we fold getelementptr's
// with a single zero index, it must be nonzero.
assert(CE1->getNumOperands() == 2 &&
!CE1->getOperand(1)->isNullValue() &&
"Suprising getelementptr!");
return Instruction::SetGT;
} else {
// If they are different globals, we don't know what the value is,
// but they can't be equal.
return Instruction::SetNE;
}
}
} else {
const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
const Constant *CE2Op0 = CE2->getOperand(0);
// There are MANY other foldings that we could perform here. They will
// probably be added on demand, as they seem needed.
switch (CE2->getOpcode()) {
default: break;
case Instruction::GetElementPtr:
// By far the most common case to handle is when the base pointers are
// obviously to the same or different globals.
if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
return Instruction::SetNE;
// Ok, we know that both getelementptr instructions are based on the
// same global. From this, we can precisely determine the relative
// ordering of the resultant pointers.
unsigned i = 1;
// Compare all of the operands the GEP's have in common.
gep_type_iterator GTI = gep_type_begin(CE1);
for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
++i, ++GTI)
switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
GTI.getIndexedType())) {
case -1: return Instruction::SetLT;
case 1: return Instruction::SetGT;
case -2: return Instruction::BinaryOpsEnd;
}
// Ok, we ran out of things they have in common. If any leftovers
// are non-zero then we have a difference, otherwise we are equal.
for (; i < CE1->getNumOperands(); ++i)
if (!CE1->getOperand(i)->isNullValue())
if (isa<ConstantIntegral>(CE1->getOperand(i)))
return Instruction::SetGT;
else
return Instruction::BinaryOpsEnd; // Might be equal.
for (; i < CE2->getNumOperands(); ++i)
if (!CE2->getOperand(i)->isNullValue())
if (isa<ConstantIntegral>(CE2->getOperand(i)))
return Instruction::SetLT;
else
return Instruction::BinaryOpsEnd; // Might be equal.
return Instruction::SetEQ;
}
}
}
default:
break;
}
}
return Instruction::BinaryOpsEnd;
}
Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
const Constant *V1,
const Constant *V2) {
Constant *C = 0;
switch (Opcode) {
default: break;
case Instruction::Add: C = ConstRules::get(V1, V2).add(V1, V2); break;
case Instruction::Sub: C = ConstRules::get(V1, V2).sub(V1, V2); break;
case Instruction::Mul: C = ConstRules::get(V1, V2).mul(V1, V2); break;
case Instruction::UDiv: C = ConstRules::get(V1, V2).udiv(V1, V2); break;
case Instruction::SDiv: C = ConstRules::get(V1, V2).sdiv(V1, V2); break;
case Instruction::FDiv: C = ConstRules::get(V1, V2).fdiv(V1, V2); break;
case Instruction::URem: C = ConstRules::get(V1, V2).urem(V1, V2); break;
case Instruction::SRem: C = ConstRules::get(V1, V2).srem(V1, V2); break;
case Instruction::FRem: C = ConstRules::get(V1, V2).frem(V1, V2); break;
case Instruction::And: C = ConstRules::get(V1, V2).op_and(V1, V2); break;
case Instruction::Or: C = ConstRules::get(V1, V2).op_or (V1, V2); break;
case Instruction::Xor: C = ConstRules::get(V1, V2).op_xor(V1, V2); break;
case Instruction::Shl: C = ConstRules::get(V1, V2).shl(V1, V2); break;
case Instruction::LShr: C = ConstRules::get(V1, V2).lshr(V1, V2); break;
case Instruction::AShr: C = ConstRules::get(V1, V2).ashr(V1, V2); break;
case Instruction::SetEQ:
// SetEQ(null,GV) -> false
if (V1->isNullValue()) {
if (const GlobalValue *GV = dyn_cast<GlobalValue>(V2))
if (!GV->hasExternalWeakLinkage())
return ConstantBool::getFalse();
// SetEQ(GV,null) -> false
} else if (V2->isNullValue()) {
if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1))
if (!GV->hasExternalWeakLinkage())
return ConstantBool::getFalse();
}
C = ConstRules::get(V1, V2).equalto(V1, V2);
break;
case Instruction::SetLT: C = ConstRules::get(V1, V2).lessthan(V1, V2);break;
case Instruction::SetGT: C = ConstRules::get(V1, V2).lessthan(V2, V1);break;
case Instruction::SetNE:
// SetNE(null,GV) -> true
if (V1->isNullValue()) {
if (const GlobalValue *GV = dyn_cast<GlobalValue>(V2))
if (!GV->hasExternalWeakLinkage())
return ConstantBool::getTrue();
// SetNE(GV,null) -> true
} else if (V2->isNullValue()) {
if (const GlobalValue *GV = dyn_cast<GlobalValue>(V1))
if (!GV->hasExternalWeakLinkage())
return ConstantBool::getTrue();
}
// V1 != V2 === !(V1 == V2)
C = ConstRules::get(V1, V2).equalto(V1, V2);
if (C) return ConstantExpr::getNot(C);
break;
case Instruction::SetLE: // V1 <= V2 === !(V2 < V1)
C = ConstRules::get(V1, V2).lessthan(V2, V1);
if (C) return ConstantExpr::getNot(C);
break;
case Instruction::SetGE: // V1 >= V2 === !(V1 < V2)
C = ConstRules::get(V1, V2).lessthan(V1, V2);
if (C) return ConstantExpr::getNot(C);
break;
}
// If we successfully folded the expression, return it now.
if (C) return C;
if (SetCondInst::isComparison(Opcode)) {
if (isa<UndefValue>(V1) || isa<UndefValue>(V2))
return UndefValue::get(Type::BoolTy);
switch (evaluateRelation(const_cast<Constant*>(V1),
const_cast<Constant*>(V2))) {
default: assert(0 && "Unknown relational!");
case Instruction::BinaryOpsEnd:
break; // Couldn't determine anything about these constants.
case Instruction::SetEQ: // We know the constants are equal!
// If we know the constants are equal, we can decide the result of this
// computation precisely.
return ConstantBool::get(Opcode == Instruction::SetEQ ||
Opcode == Instruction::SetLE ||
Opcode == Instruction::SetGE);
case Instruction::SetLT:
// If we know that V1 < V2, we can decide the result of this computation
// precisely.
return ConstantBool::get(Opcode == Instruction::SetLT ||
Opcode == Instruction::SetNE ||
Opcode == Instruction::SetLE);
case Instruction::SetGT:
// If we know that V1 > V2, we can decide the result of this computation
// precisely.
return ConstantBool::get(Opcode == Instruction::SetGT ||
Opcode == Instruction::SetNE ||
Opcode == Instruction::SetGE);
case Instruction::SetLE:
// If we know that V1 <= V2, we can only partially decide this relation.
if (Opcode == Instruction::SetGT) return ConstantBool::getFalse();
if (Opcode == Instruction::SetLT) return ConstantBool::getTrue();
break;
case Instruction::SetGE:
// If we know that V1 >= V2, we can only partially decide this relation.
if (Opcode == Instruction::SetLT) return ConstantBool::getFalse();
if (Opcode == Instruction::SetGT) return ConstantBool::getTrue();
break;
case Instruction::SetNE:
// If we know that V1 != V2, we can only partially decide this relation.
if (Opcode == Instruction::SetEQ) return ConstantBool::getFalse();
if (Opcode == Instruction::SetNE) return ConstantBool::getTrue();
break;
}
}
if (isa<UndefValue>(V1) || isa<UndefValue>(V2)) {
switch (Opcode) {
case Instruction::Add:
case Instruction::Sub:
case Instruction::Xor:
return UndefValue::get(V1->getType());
case Instruction::Mul:
case Instruction::And:
return Constant::getNullValue(V1->getType());
case Instruction::UDiv:
case Instruction::SDiv:
case Instruction::FDiv:
case Instruction::URem:
case Instruction::SRem:
case Instruction::FRem:
if (!isa<UndefValue>(V2)) // undef / X -> 0
return Constant::getNullValue(V1->getType());
return const_cast<Constant*>(V2); // X / undef -> undef
case Instruction::Or: // X | undef -> -1
return ConstantInt::getAllOnesValue(V1->getType());
case Instruction::LShr:
if (isa<UndefValue>(V2) && isa<UndefValue>(V1))
return const_cast<Constant*>(V1); // undef lshr undef -> undef
return Constant::getNullValue(V1->getType()); // X lshr undef -> 0
// undef lshr X -> 0
case Instruction::AShr:
if (!isa<UndefValue>(V2))
return const_cast<Constant*>(V1); // undef ashr X --> undef
else if (isa<UndefValue>(V1))
return const_cast<Constant*>(V1); // undef ashr undef -> undef
else
return const_cast<Constant*>(V1); // X ashr undef --> X
case Instruction::Shl:
// undef << X -> 0 or X << undef -> 0
return Constant::getNullValue(V1->getType());
}
}
if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(V1)) {
if (isa<ConstantExpr>(V2)) {
// There are many possible foldings we could do here. We should probably
// at least fold add of a pointer with an integer into the appropriate
// getelementptr. This will improve alias analysis a bit.
} else {
// Just implement a couple of simple identities.
switch (Opcode) {
case Instruction::Add:
if (V2->isNullValue()) return const_cast<Constant*>(V1); // X + 0 == X
break;
case Instruction::Sub:
if (V2->isNullValue()) return const_cast<Constant*>(V1); // X - 0 == X
break;
case Instruction::Mul:
if (V2->isNullValue()) return const_cast<Constant*>(V2); // X * 0 == 0
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
if (CI->getZExtValue() == 1)
return const_cast<Constant*>(V1); // X * 1 == X
break;
case Instruction::UDiv:
case Instruction::SDiv:
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
if (CI->getZExtValue() == 1)
return const_cast<Constant*>(V1); // X / 1 == X
break;
case Instruction::URem:
case Instruction::SRem:
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
if (CI->getZExtValue() == 1)
return Constant::getNullValue(CI->getType()); // X % 1 == 0
break;
case Instruction::And:
if (cast<ConstantIntegral>(V2)->isAllOnesValue())
return const_cast<Constant*>(V1); // X & -1 == X
if (V2->isNullValue()) return const_cast<Constant*>(V2); // X & 0 == 0
if (CE1->isCast() && isa<GlobalValue>(CE1->getOperand(0))) {
GlobalValue *CPR = cast<GlobalValue>(CE1->getOperand(0));
// Functions are at least 4-byte aligned. If and'ing the address of a
// function with a constant < 4, fold it to zero.
if (const ConstantInt *CI = dyn_cast<ConstantInt>(V2))
if (CI->getZExtValue() < 4 && isa<Function>(CPR))
return Constant::getNullValue(CI->getType());
}
break;
case Instruction::Or:
if (V2->isNullValue()) return const_cast<Constant*>(V1); // X | 0 == X
if (cast<ConstantIntegral>(V2)->isAllOnesValue())
return const_cast<Constant*>(V2); // X | -1 == -1
break;
case Instruction::Xor:
if (V2->isNullValue()) return const_cast<Constant*>(V1); // X ^ 0 == X
break;
}
}
} else if (isa<ConstantExpr>(V2)) {
// If V2 is a constant expr and V1 isn't, flop them around and fold the
// other way if possible.
switch (Opcode) {
case Instruction::Add:
case Instruction::Mul:
case Instruction::And:
case Instruction::Or:
case Instruction::Xor:
case Instruction::SetEQ:
case Instruction::SetNE:
// No change of opcode required.
return ConstantFoldBinaryInstruction(Opcode, V2, V1);
case Instruction::SetLT:
case Instruction::SetGT:
case Instruction::SetLE:
case Instruction::SetGE:
// Change the opcode as necessary to swap the operands.
Opcode = SetCondInst::getSwappedCondition((Instruction::BinaryOps)Opcode);
return ConstantFoldBinaryInstruction(Opcode, V2, V1);
case Instruction::Shl:
case Instruction::LShr:
case Instruction::AShr:
case Instruction::Sub:
case Instruction::SDiv:
case Instruction::UDiv:
case Instruction::FDiv:
case Instruction::URem:
case Instruction::SRem:
case Instruction::FRem:
default: // These instructions cannot be flopped around.
break;
}
}
return 0;
}
Constant *llvm::ConstantFoldCompare(
unsigned opcode, Constant *C1, Constant *C2, unsigned short predicate)
{
// Place holder for future folding of ICmp and FCmp instructions
return 0;
}
Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
const std::vector<Value*> &IdxList) {
if (IdxList.size() == 0 ||
(IdxList.size() == 1 && cast<Constant>(IdxList[0])->isNullValue()))
return const_cast<Constant*>(C);
if (isa<UndefValue>(C)) {
const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
true);
assert(Ty != 0 && "Invalid indices for GEP!");
return UndefValue::get(PointerType::get(Ty));
}
Constant *Idx0 = cast<Constant>(IdxList[0]);
if (C->isNullValue()) {
bool isNull = true;
for (unsigned i = 0, e = IdxList.size(); i != e; ++i)
if (!cast<Constant>(IdxList[i])->isNullValue()) {
isNull = false;
break;
}
if (isNull) {
const Type *Ty = GetElementPtrInst::getIndexedType(C->getType(), IdxList,
true);
assert(Ty != 0 && "Invalid indices for GEP!");
return ConstantPointerNull::get(PointerType::get(Ty));
}
if (IdxList.size() == 1) {
const Type *ElTy = cast<PointerType>(C->getType())->getElementType();
if (uint32_t ElSize = ElTy->getPrimitiveSize()) {
// gep null, C is equal to C*sizeof(nullty). If nullty is a known llvm
// type, we can statically fold this.
Constant *R = ConstantInt::get(Type::UIntTy, ElSize);
// We know R is unsigned, Idx0 is signed because it must be an index
// through a sequential type (gep pointer operand) which is always
// signed.
R = ConstantExpr::getSExtOrBitCast(R, Idx0->getType());
R = ConstantExpr::getMul(R, Idx0); // signed multiply
// R is a signed integer, C is the GEP pointer so -> IntToPtr
return ConstantExpr::getIntToPtr(R, C->getType());
}
}
}
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
// Combine Indices - If the source pointer to this getelementptr instruction
// is a getelementptr instruction, combine the indices of the two
// getelementptr instructions into a single instruction.
//
if (CE->getOpcode() == Instruction::GetElementPtr) {
const Type *LastTy = 0;
for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
I != E; ++I)
LastTy = *I;
if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
std::vector<Value*> NewIndices;
NewIndices.reserve(IdxList.size() + CE->getNumOperands());
for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
NewIndices.push_back(CE->getOperand(i));
// Add the last index of the source with the first index of the new GEP.
// Make sure to handle the case when they are actually different types.
Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
// Otherwise it must be an array.
if (!Idx0->isNullValue()) {
const Type *IdxTy = Combined->getType();
if (IdxTy != Idx0->getType()) {
Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::LongTy);
Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
Type::LongTy);
Combined = ConstantExpr::get(Instruction::Add, C1, C2);
} else {
Combined =
ConstantExpr::get(Instruction::Add, Idx0, Combined);
}
}
NewIndices.push_back(Combined);
NewIndices.insert(NewIndices.end(), IdxList.begin()+1, IdxList.end());
return ConstantExpr::getGetElementPtr(CE->getOperand(0), NewIndices);
}
}
// Implement folding of:
// int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
// long 0, long 0)
// To: int* getelementptr ([3 x int]* %X, long 0, long 0)
//
if (CE->isCast() && IdxList.size() > 1 && Idx0->isNullValue())
if (const PointerType *SPT =
dyn_cast<PointerType>(CE->getOperand(0)->getType()))
if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
if (const ArrayType *CAT =
dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
if (CAT->getElementType() == SAT->getElementType())
return ConstantExpr::getGetElementPtr(
(Constant*)CE->getOperand(0), IdxList);
}
return 0;
}
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