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llvm/lib/Analysis/InstructionSimplify.cpp
Sanjay Patel f59206d480 [InstSimplify] use computeKnownBits on shift amount operands 
Do simplifications common to all shift instructions based on the amount shifted:
1. If the shift amount is known larger than the bitwidth, the result is undefined.
2. If the valid bits of the shift amount are all known to be 0, it's a shift by zero, so the shift operand is the result.

Note that we could generalize the shift-by-zero transform into a shift-by-constant if all of the valid bits in the shift
amount are known, but that would have to be done in InstCombine rather than here because it would mean we need to create
a new shift instruction.

Differential Revision: http://reviews.llvm.org/D19874



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269114 91177308-0d34-0410-b5e6-96231b3b80d8
2016-05-10 20:46:54 +00:00

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//===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements routines for folding instructions into simpler forms
// that do not require creating new instructions. This does constant folding
// ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
// returning a constant ("and i32 %x, 0" -> "0") or an already existing value
// ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been
// simplified: This is usually true and assuming it simplifies the logic (if
// they have not been simplified then results are correct but maybe suboptimal).
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/ValueHandle.h"
#include <algorithm>
using namespace llvm;
using namespace llvm::PatternMatch;
#define DEBUG_TYPE "instsimplify"
enum { RecursionLimit = 3 };
STATISTIC(NumExpand, "Number of expansions");
STATISTIC(NumReassoc, "Number of reassociations");
namespace {
struct Query {
const DataLayout &DL;
const TargetLibraryInfo *TLI;
const DominatorTree *DT;
AssumptionCache *AC;
const Instruction *CxtI;
Query(const DataLayout &DL, const TargetLibraryInfo *tli,
const DominatorTree *dt, AssumptionCache *ac = nullptr,
const Instruction *cxti = nullptr)
: DL(DL), TLI(tli), DT(dt), AC(ac), CxtI(cxti) {}
};
} // end anonymous namespace
static Value *SimplifyAndInst(Value *, Value *, const Query &, unsigned);
static Value *SimplifyBinOp(unsigned, Value *, Value *, const Query &,
unsigned);
static Value *SimplifyFPBinOp(unsigned, Value *, Value *, const FastMathFlags &,
const Query &, unsigned);
static Value *SimplifyCmpInst(unsigned, Value *, Value *, const Query &,
unsigned);
static Value *SimplifyOrInst(Value *, Value *, const Query &, unsigned);
static Value *SimplifyXorInst(Value *, Value *, const Query &, unsigned);
static Value *SimplifyTruncInst(Value *, Type *, const Query &, unsigned);
/// For a boolean type, or a vector of boolean type, return false, or
/// a vector with every element false, as appropriate for the type.
static Constant *getFalse(Type *Ty) {
assert(Ty->getScalarType()->isIntegerTy(1) &&
"Expected i1 type or a vector of i1!");
return Constant::getNullValue(Ty);
}
/// For a boolean type, or a vector of boolean type, return true, or
/// a vector with every element true, as appropriate for the type.
static Constant *getTrue(Type *Ty) {
assert(Ty->getScalarType()->isIntegerTy(1) &&
"Expected i1 type or a vector of i1!");
return Constant::getAllOnesValue(Ty);
}
/// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"?
static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS,
Value *RHS) {
CmpInst *Cmp = dyn_cast<CmpInst>(V);
if (!Cmp)
return false;
CmpInst::Predicate CPred = Cmp->getPredicate();
Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1);
if (CPred == Pred && CLHS == LHS && CRHS == RHS)
return true;
return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS &&
CRHS == LHS;
}
/// Does the given value dominate the specified phi node?
static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
Instruction *I = dyn_cast<Instruction>(V);
if (!I)
// Arguments and constants dominate all instructions.
return true;
// If we are processing instructions (and/or basic blocks) that have not been
// fully added to a function, the parent nodes may still be null. Simply
// return the conservative answer in these cases.
if (!I->getParent() || !P->getParent() || !I->getParent()->getParent())
return false;
// If we have a DominatorTree then do a precise test.
if (DT) {
if (!DT->isReachableFromEntry(P->getParent()))
return true;
if (!DT->isReachableFromEntry(I->getParent()))
return false;
return DT->dominates(I, P);
}
// Otherwise, if the instruction is in the entry block and is not an invoke,
// then it obviously dominates all phi nodes.
if (I->getParent() == &I->getParent()->getParent()->getEntryBlock() &&
!isa<InvokeInst>(I))
return true;
return false;
}
/// Simplify "A op (B op' C)" by distributing op over op', turning it into
/// "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
/// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
/// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
/// Returns the simplified value, or null if no simplification was performed.
static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
unsigned OpcToExpand, const Query &Q,
unsigned MaxRecurse) {
Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return nullptr;
// Check whether the expression has the form "(A op' B) op C".
if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
if (Op0->getOpcode() == OpcodeToExpand) {
// It does! Try turning it into "(A op C) op' (B op C)".
Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
// Do "A op C" and "B op C" both simplify?
if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse))
if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
// They do! Return "L op' R" if it simplifies or is already available.
// If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
&& L == B && R == A)) {
++NumExpand;
return LHS;
}
// Otherwise return "L op' R" if it simplifies.
if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
++NumExpand;
return V;
}
}
}
// Check whether the expression has the form "A op (B op' C)".
if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
if (Op1->getOpcode() == OpcodeToExpand) {
// It does! Try turning it into "(A op B) op' (A op C)".
Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
// Do "A op B" and "A op C" both simplify?
if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse))
if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) {
// They do! Return "L op' R" if it simplifies or is already available.
// If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
&& L == C && R == B)) {
++NumExpand;
return RHS;
}
// Otherwise return "L op' R" if it simplifies.
if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) {
++NumExpand;
return V;
}
}
}
return nullptr;
}
/// Generic simplifications for associative binary operations.
/// Returns the simpler value, or null if none was found.
static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
const Query &Q, unsigned MaxRecurse) {
Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return nullptr;
BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
// Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
if (Op0 && Op0->getOpcode() == Opcode) {
Value *A = Op0->getOperand(0);
Value *B = Op0->getOperand(1);
Value *C = RHS;
// Does "B op C" simplify?
if (Value *V = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) {
// It does! Return "A op V" if it simplifies or is already available.
// If V equals B then "A op V" is just the LHS.
if (V == B) return LHS;
// Otherwise return "A op V" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, A, V, Q, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
// Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
if (Op1 && Op1->getOpcode() == Opcode) {
Value *A = LHS;
Value *B = Op1->getOperand(0);
Value *C = Op1->getOperand(1);
// Does "A op B" simplify?
if (Value *V = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) {
// It does! Return "V op C" if it simplifies or is already available.
// If V equals B then "V op C" is just the RHS.
if (V == B) return RHS;
// Otherwise return "V op C" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, V, C, Q, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
// The remaining transforms require commutativity as well as associativity.
if (!Instruction::isCommutative(Opcode))
return nullptr;
// Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
if (Op0 && Op0->getOpcode() == Opcode) {
Value *A = Op0->getOperand(0);
Value *B = Op0->getOperand(1);
Value *C = RHS;
// Does "C op A" simplify?
if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
// It does! Return "V op B" if it simplifies or is already available.
// If V equals A then "V op B" is just the LHS.
if (V == A) return LHS;
// Otherwise return "V op B" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, V, B, Q, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
// Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
if (Op1 && Op1->getOpcode() == Opcode) {
Value *A = LHS;
Value *B = Op1->getOperand(0);
Value *C = Op1->getOperand(1);
// Does "C op A" simplify?
if (Value *V = SimplifyBinOp(Opcode, C, A, Q, MaxRecurse)) {
// It does! Return "B op V" if it simplifies or is already available.
// If V equals C then "B op V" is just the RHS.
if (V == C) return RHS;
// Otherwise return "B op V" if it simplifies.
if (Value *W = SimplifyBinOp(Opcode, B, V, Q, MaxRecurse)) {
++NumReassoc;
return W;
}
}
}
return nullptr;
}
/// In the case of a binary operation with a select instruction as an operand,
/// try to simplify the binop by seeing whether evaluating it on both branches
/// of the select results in the same value. Returns the common value if so,
/// otherwise returns null.
static Value *ThreadBinOpOverSelect(unsigned Opcode, Value *LHS, Value *RHS,
const Query &Q, unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return nullptr;
SelectInst *SI;
if (isa<SelectInst>(LHS)) {
SI = cast<SelectInst>(LHS);
} else {
assert(isa<SelectInst>(RHS) && "No select instruction operand!");
SI = cast<SelectInst>(RHS);
}
// Evaluate the BinOp on the true and false branches of the select.
Value *TV;
Value *FV;
if (SI == LHS) {
TV = SimplifyBinOp(Opcode, SI->getTrueValue(), RHS, Q, MaxRecurse);
FV = SimplifyBinOp(Opcode, SI->getFalseValue(), RHS, Q, MaxRecurse);
} else {
TV = SimplifyBinOp(Opcode, LHS, SI->getTrueValue(), Q, MaxRecurse);
FV = SimplifyBinOp(Opcode, LHS, SI->getFalseValue(), Q, MaxRecurse);
}
// If they simplified to the same value, then return the common value.
// If they both failed to simplify then return null.
if (TV == FV)
return TV;
// If one branch simplified to undef, return the other one.
if (TV && isa<UndefValue>(TV))
return FV;
if (FV && isa<UndefValue>(FV))
return TV;
// If applying the operation did not change the true and false select values,
// then the result of the binop is the select itself.
if (TV == SI->getTrueValue() && FV == SI->getFalseValue())
return SI;
// If one branch simplified and the other did not, and the simplified
// value is equal to the unsimplified one, return the simplified value.
// For example, select (cond, X, X & Z) & Z -> X & Z.
if ((FV && !TV) || (TV && !FV)) {
// Check that the simplified value has the form "X op Y" where "op" is the
// same as the original operation.
Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV);
if (Simplified && Simplified->getOpcode() == Opcode) {
// The value that didn't simplify is "UnsimplifiedLHS op UnsimplifiedRHS".
// We already know that "op" is the same as for the simplified value. See
// if the operands match too. If so, return the simplified value.
Value *UnsimplifiedBranch = FV ? SI->getTrueValue() : SI->getFalseValue();
Value *UnsimplifiedLHS = SI == LHS ? UnsimplifiedBranch : LHS;
Value *UnsimplifiedRHS = SI == LHS ? RHS : UnsimplifiedBranch;
if (Simplified->getOperand(0) == UnsimplifiedLHS &&
Simplified->getOperand(1) == UnsimplifiedRHS)
return Simplified;
if (Simplified->isCommutative() &&
Simplified->getOperand(1) == UnsimplifiedLHS &&
Simplified->getOperand(0) == UnsimplifiedRHS)
return Simplified;
}
}
return nullptr;
}
/// In the case of a comparison with a select instruction, try to simplify the
/// comparison by seeing whether both branches of the select result in the same
/// value. Returns the common value if so, otherwise returns null.
static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const Query &Q,
unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return nullptr;
// Make sure the select is on the LHS.
if (!isa<SelectInst>(LHS)) {
std::swap(LHS, RHS);
Pred = CmpInst::getSwappedPredicate(Pred);
}
assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
SelectInst *SI = cast<SelectInst>(LHS);
Value *Cond = SI->getCondition();
Value *TV = SI->getTrueValue();
Value *FV = SI->getFalseValue();
// Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
// Does "cmp TV, RHS" simplify?
Value *TCmp = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse);
if (TCmp == Cond) {
// It not only simplified, it simplified to the select condition. Replace
// it with 'true'.
TCmp = getTrue(Cond->getType());
} else if (!TCmp) {
// It didn't simplify. However if "cmp TV, RHS" is equal to the select
// condition then we can replace it with 'true'. Otherwise give up.
if (!isSameCompare(Cond, Pred, TV, RHS))
return nullptr;
TCmp = getTrue(Cond->getType());
}
// Does "cmp FV, RHS" simplify?
Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse);
if (FCmp == Cond) {
// It not only simplified, it simplified to the select condition. Replace
// it with 'false'.
FCmp = getFalse(Cond->getType());
} else if (!FCmp) {
// It didn't simplify. However if "cmp FV, RHS" is equal to the select
// condition then we can replace it with 'false'. Otherwise give up.
if (!isSameCompare(Cond, Pred, FV, RHS))
return nullptr;
FCmp = getFalse(Cond->getType());
}
// If both sides simplified to the same value, then use it as the result of
// the original comparison.
if (TCmp == FCmp)
return TCmp;
// The remaining cases only make sense if the select condition has the same
// type as the result of the comparison, so bail out if this is not so.
if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy())
return nullptr;
// If the false value simplified to false, then the result of the compare
// is equal to "Cond && TCmp". This also catches the case when the false
// value simplified to false and the true value to true, returning "Cond".
if (match(FCmp, m_Zero()))
if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse))
return V;
// If the true value simplified to true, then the result of the compare
// is equal to "Cond || FCmp".
if (match(TCmp, m_One()))
if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse))
return V;
// Finally, if the false value simplified to true and the true value to
// false, then the result of the compare is equal to "!Cond".
if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
if (Value *V =
SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
Q, MaxRecurse))
return V;
return nullptr;
}
/// In the case of a binary operation with an operand that is a PHI instruction,
/// try to simplify the binop by seeing whether evaluating it on the incoming
/// phi values yields the same result for every value. If so returns the common
/// value, otherwise returns null.
static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
const Query &Q, unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return nullptr;
PHINode *PI;
if (isa<PHINode>(LHS)) {
PI = cast<PHINode>(LHS);
// Bail out if RHS and the phi may be mutually interdependent due to a loop.
if (!ValueDominatesPHI(RHS, PI, Q.DT))
return nullptr;
} else {
assert(isa<PHINode>(RHS) && "No PHI instruction operand!");
PI = cast<PHINode>(RHS);
// Bail out if LHS and the phi may be mutually interdependent due to a loop.
if (!ValueDominatesPHI(LHS, PI, Q.DT))
return nullptr;
}
// Evaluate the BinOp on the incoming phi values.
Value *CommonValue = nullptr;
for (Value *Incoming : PI->incoming_values()) {
// If the incoming value is the phi node itself, it can safely be skipped.
if (Incoming == PI) continue;
Value *V = PI == LHS ?
SimplifyBinOp(Opcode, Incoming, RHS, Q, MaxRecurse) :
SimplifyBinOp(Opcode, LHS, Incoming, Q, MaxRecurse);
// If the operation failed to simplify, or simplified to a different value
// to previously, then give up.
if (!V || (CommonValue && V != CommonValue))
return nullptr;
CommonValue = V;
}
return CommonValue;
}
/// In the case of a comparison with a PHI instruction, try to simplify the
/// comparison by seeing whether comparing with all of the incoming phi values
/// yields the same result every time. If so returns the common result,
/// otherwise returns null.
static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
const Query &Q, unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return nullptr;
// Make sure the phi is on the LHS.
if (!isa<PHINode>(LHS)) {
std::swap(LHS, RHS);
Pred = CmpInst::getSwappedPredicate(Pred);
}
assert(isa<PHINode>(LHS) && "Not comparing with a phi instruction!");
PHINode *PI = cast<PHINode>(LHS);
// Bail out if RHS and the phi may be mutually interdependent due to a loop.
if (!ValueDominatesPHI(RHS, PI, Q.DT))
return nullptr;
// Evaluate the BinOp on the incoming phi values.
Value *CommonValue = nullptr;
for (Value *Incoming : PI->incoming_values()) {
// If the incoming value is the phi node itself, it can safely be skipped.
if (Incoming == PI) continue;
Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse);
// If the operation failed to simplify, or simplified to a different value
// to previously, then give up.
if (!V || (CommonValue && V != CommonValue))
return nullptr;
CommonValue = V;
}
return CommonValue;
}
/// Given operands for an Add, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const Query &Q, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Instruction::Add, CLHS, CRHS, Q.DL);
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X + undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// X + 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// X + (Y - X) -> Y
// (Y - X) + X -> Y
// Eg: X + -X -> 0
Value *Y = nullptr;
if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
return Y;
// X + ~X -> -1 since ~X = -X-1
if (match(Op0, m_Not(m_Specific(Op1))) ||
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getAllOnesValue(Op0->getType());
/// i1 add -> xor.
if (MaxRecurse && Op0->getType()->isIntegerTy(1))
if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
return V;
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, Q,
MaxRecurse))
return V;
// Threading Add over selects and phi nodes is pointless, so don't bother.
// Threading over the select in "A + select(cond, B, C)" means evaluating
// "A+B" and "A+C" and seeing if they are equal; but they are equal if and
// only if B and C are equal. If B and C are equal then (since we assume
// that operands have already been simplified) "select(cond, B, C)" should
// have been simplified to the common value of B and C already. Analysing
// "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
// for threading over phi nodes.
return nullptr;
}
Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const DataLayout &DL, const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// \brief Compute the base pointer and cumulative constant offsets for V.
///
/// This strips all constant offsets off of V, leaving it the base pointer, and
/// accumulates the total constant offset applied in the returned constant. It
/// returns 0 if V is not a pointer, and returns the constant '0' if there are
/// no constant offsets applied.
///
/// This is very similar to GetPointerBaseWithConstantOffset except it doesn't
/// follow non-inbounds geps. This allows it to remain usable for icmp ult/etc.
/// folding.
static Constant *stripAndComputeConstantOffsets(const DataLayout &DL, Value *&V,
bool AllowNonInbounds = false) {
assert(V->getType()->getScalarType()->isPointerTy());
Type *IntPtrTy = DL.getIntPtrType(V->getType())->getScalarType();
APInt Offset = APInt::getNullValue(IntPtrTy->getIntegerBitWidth());
// Even though we don't look through PHI nodes, we could be called on an
// instruction in an unreachable block, which may be on a cycle.
SmallPtrSet<Value *, 4> Visited;
Visited.insert(V);
do {
if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
if ((!AllowNonInbounds && !GEP->isInBounds()) ||
!GEP->accumulateConstantOffset(DL, Offset))
break;
V = GEP->getPointerOperand();
} else if (Operator::getOpcode(V) == Instruction::BitCast) {
V = cast<Operator>(V)->getOperand(0);
} else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
if (GA->isInterposable())
break;
V = GA->getAliasee();
} else {
break;
}
assert(V->getType()->getScalarType()->isPointerTy() &&
"Unexpected operand type!");
} while (Visited.insert(V).second);
Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset);
if (V->getType()->isVectorTy())
return ConstantVector::getSplat(V->getType()->getVectorNumElements(),
OffsetIntPtr);
return OffsetIntPtr;
}
/// \brief Compute the constant difference between two pointer values.
/// If the difference is not a constant, returns zero.
static Constant *computePointerDifference(const DataLayout &DL, Value *LHS,
Value *RHS) {
Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
// If LHS and RHS are not related via constant offsets to the same base
// value, there is nothing we can do here.
if (LHS != RHS)
return nullptr;
// Otherwise, the difference of LHS - RHS can be computed as:
// LHS - RHS
// = (LHSOffset + Base) - (RHSOffset + Base)
// = LHSOffset - RHSOffset
return ConstantExpr::getSub(LHSOffset, RHSOffset);
}
/// Given operands for a Sub, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const Query &Q, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0))
if (Constant *CRHS = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Instruction::Sub, CLHS, CRHS, Q.DL);
// X - undef -> undef
// undef - X -> undef
if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
return UndefValue::get(Op0->getType());
// X - 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// X - X -> 0
if (Op0 == Op1)
return Constant::getNullValue(Op0->getType());
// 0 - X -> 0 if the sub is NUW.
if (isNUW && match(Op0, m_Zero()))
return Op0;
// (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
// For example, (X + Y) - Y -> X; (Y + X) - Y -> X
Value *X = nullptr, *Y = nullptr, *Z = Op1;
if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
// See if "V === Y - Z" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1))
// It does! Now see if "X + V" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
// See if "V === X - Z" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
// It does! Now see if "Y + V" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
}
// X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
// For example, X - (X + 1) -> -1
X = Op0;
if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
// See if "V === X - Y" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
// It does! Now see if "V - Z" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
// See if "V === X - Z" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1))
// It does! Now see if "V - Y" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
}
// Z - (X - Y) -> (Z - X) + Y if everything simplifies.
// For example, X - (X - Y) -> Y.
Z = Op0;
if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
// See if "V === Z - X" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1))
// It does! Now see if "V + Y" simplifies.
if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) {
// It does, we successfully reassociated!
++NumReassoc;
return W;
}
// trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies.
if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) &&
match(Op1, m_Trunc(m_Value(Y))))
if (X->getType() == Y->getType())
// See if "V === X - Y" simplifies.
if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1))
// It does! Now see if "trunc V" simplifies.
if (Value *W = SimplifyTruncInst(V, Op0->getType(), Q, MaxRecurse-1))
// It does, return the simplified "trunc V".
return W;
// Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
if (match(Op0, m_PtrToInt(m_Value(X))) &&
match(Op1, m_PtrToInt(m_Value(Y))))
if (Constant *Result = computePointerDifference(Q.DL, X, Y))
return ConstantExpr::getIntegerCast(Result, Op0->getType(), true);
// i1 sub -> xor.
if (MaxRecurse && Op0->getType()->isIntegerTy(1))
if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1))
return V;
// Threading Sub over selects and phi nodes is pointless, so don't bother.
// Threading over the select in "A - select(cond, B, C)" means evaluating
// "A-B" and "A-C" and seeing if they are equal; but they are equal if and
// only if B and C are equal. If B and C are equal then (since we assume
// that operands have already been simplified) "select(cond, B, C)" should
// have been simplified to the common value of B and C already. Analysing
// "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
// for threading over phi nodes.
return nullptr;
}
Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const DataLayout &DL, const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for an FAdd, see if we can fold the result. If not, this
/// returns null.
static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const Query &Q, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Instruction::FAdd, CLHS, CRHS, Q.DL);
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// fadd X, -0 ==> X
if (match(Op1, m_NegZero()))
return Op0;
// fadd X, 0 ==> X, when we know X is not -0
if (match(Op1, m_Zero()) &&
(FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
return Op0;
// fadd [nnan ninf] X, (fsub [nnan ninf] 0, X) ==> 0
// where nnan and ninf have to occur at least once somewhere in this
// expression
Value *SubOp = nullptr;
if (match(Op1, m_FSub(m_AnyZero(), m_Specific(Op0))))
SubOp = Op1;
else if (match(Op0, m_FSub(m_AnyZero(), m_Specific(Op1))))
SubOp = Op0;
if (SubOp) {
Instruction *FSub = cast<Instruction>(SubOp);
if ((FMF.noNaNs() || FSub->hasNoNaNs()) &&
(FMF.noInfs() || FSub->hasNoInfs()))
return Constant::getNullValue(Op0->getType());
}
return nullptr;
}
/// Given operands for an FSub, see if we can fold the result. If not, this
/// returns null.
static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const Query &Q, unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Instruction::FSub, CLHS, CRHS, Q.DL);
}
// fsub X, 0 ==> X
if (match(Op1, m_Zero()))
return Op0;
// fsub X, -0 ==> X, when we know X is not -0
if (match(Op1, m_NegZero()) &&
(FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
return Op0;
// fsub -0.0, (fsub -0.0, X) ==> X
Value *X;
if (match(Op0, m_NegZero()) && match(Op1, m_FSub(m_NegZero(), m_Value(X))))
return X;
// fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored.
if (FMF.noSignedZeros() && match(Op0, m_AnyZero()) &&
match(Op1, m_FSub(m_AnyZero(), m_Value(X))))
return X;
// fsub nnan x, x ==> 0.0
if (FMF.noNaNs() && Op0 == Op1)
return Constant::getNullValue(Op0->getType());
return nullptr;
}
/// Given the operands for an FMul, see if we can fold the result
static Value *SimplifyFMulInst(Value *Op0, Value *Op1,
FastMathFlags FMF,
const Query &Q,
unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Instruction::FMul, CLHS, CRHS, Q.DL);
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// fmul X, 1.0 ==> X
if (match(Op1, m_FPOne()))
return Op0;
// fmul nnan nsz X, 0 ==> 0
if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZero()))
return Op1;
return nullptr;
}
/// Given operands for a Mul, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyMulInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Instruction::Mul, CLHS, CRHS, Q.DL);
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X * undef -> 0
if (match(Op1, m_Undef()))
return Constant::getNullValue(Op0->getType());
// X * 0 -> 0
if (match(Op1, m_Zero()))
return Op1;
// X * 1 -> X
if (match(Op1, m_One()))
return Op0;
// (X / Y) * Y -> X if the division is exact.
Value *X = nullptr;
if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
return X;
// i1 mul -> and.
if (MaxRecurse && Op0->getType()->isIntegerTy(1))
if (Value *V = SimplifyAndInst(Op0, Op1, Q, MaxRecurse-1))
return V;
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, Q,
MaxRecurse))
return V;
// Mul distributes over Add. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
Q, MaxRecurse))
return V;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q,
MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q,
MaxRecurse))
return V;
return nullptr;
}
Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyFAddInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyFSubInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyFMulInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyMulInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for an SDiv or UDiv, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
const Query &Q, unsigned MaxRecurse) {
if (Constant *C0 = dyn_cast<Constant>(Op0))
if (Constant *C1 = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Opcode, C0, C1, Q.DL);
bool isSigned = Opcode == Instruction::SDiv;
// X / undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// X / 0 -> undef, we don't need to preserve faults!
if (match(Op1, m_Zero()))
return UndefValue::get(Op1->getType());
// undef / X -> 0
if (match(Op0, m_Undef()))
return Constant::getNullValue(Op0->getType());
// 0 / X -> 0, we don't need to preserve faults!
if (match(Op0, m_Zero()))
return Op0;
// X / 1 -> X
if (match(Op1, m_One()))
return Op0;
if (Op0->getType()->isIntegerTy(1))
// It can't be division by zero, hence it must be division by one.
return Op0;
// X / X -> 1
if (Op0 == Op1)
return ConstantInt::get(Op0->getType(), 1);
// (X * Y) / Y -> X if the multiplication does not overflow.
Value *X = nullptr, *Y = nullptr;
if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
OverflowingBinaryOperator *Mul = cast<OverflowingBinaryOperator>(Op0);
// If the Mul knows it does not overflow, then we are good to go.
if ((isSigned && Mul->hasNoSignedWrap()) ||
(!isSigned && Mul->hasNoUnsignedWrap()))
return X;
// If X has the form X = A / Y then X * Y cannot overflow.
if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
return X;
}
// (X rem Y) / Y -> 0
if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
(!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
return Constant::getNullValue(Op0->getType());
// (X /u C1) /u C2 -> 0 if C1 * C2 overflow
ConstantInt *C1, *C2;
if (!isSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) &&
match(Op1, m_ConstantInt(C2))) {
bool Overflow;
C1->getValue().umul_ov(C2->getValue(), Overflow);
if (Overflow)
return Constant::getNullValue(Op0->getType());
}
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
return V;
return nullptr;
}
/// Given operands for an SDiv, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifySDivInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse))
return V;
return nullptr;
}
Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifySDivInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for a UDiv, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse))
return V;
return nullptr;
}
Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyUDivInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
static Value *SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const Query &Q, unsigned) {
// undef / X -> undef (the undef could be a snan).
if (match(Op0, m_Undef()))
return Op0;
// X / undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// 0 / X -> 0
// Requires that NaNs are off (X could be zero) and signed zeroes are
// ignored (X could be positive or negative, so the output sign is unknown).
if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero()))
return Op0;
if (FMF.noNaNs()) {
// X / X -> 1.0 is legal when NaNs are ignored.
if (Op0 == Op1)
return ConstantFP::get(Op0->getType(), 1.0);
// -X / X -> -1.0 and
// X / -X -> -1.0 are legal when NaNs are ignored.
// We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored.
if ((BinaryOperator::isFNeg(Op0, /*IgnoreZeroSign=*/true) &&
BinaryOperator::getFNegArgument(Op0) == Op1) ||
(BinaryOperator::isFNeg(Op1, /*IgnoreZeroSign=*/true) &&
BinaryOperator::getFNegArgument(Op1) == Op0))
return ConstantFP::get(Op0->getType(), -1.0);
}
return nullptr;
}
Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyFDivInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for an SRem or URem, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
const Query &Q, unsigned MaxRecurse) {
if (Constant *C0 = dyn_cast<Constant>(Op0))
if (Constant *C1 = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Opcode, C0, C1, Q.DL);
// X % undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// undef % X -> 0
if (match(Op0, m_Undef()))
return Constant::getNullValue(Op0->getType());
// 0 % X -> 0, we don't need to preserve faults!
if (match(Op0, m_Zero()))
return Op0;
// X % 0 -> undef, we don't need to preserve faults!
if (match(Op1, m_Zero()))
return UndefValue::get(Op0->getType());
// X % 1 -> 0
if (match(Op1, m_One()))
return Constant::getNullValue(Op0->getType());
if (Op0->getType()->isIntegerTy(1))
// It can't be remainder by zero, hence it must be remainder by one.
return Constant::getNullValue(Op0->getType());
// X % X -> 0
if (Op0 == Op1)
return Constant::getNullValue(Op0->getType());
// (X % Y) % Y -> X % Y
if ((Opcode == Instruction::SRem &&
match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
(Opcode == Instruction::URem &&
match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
return Op0;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
return V;
return nullptr;
}
/// Given operands for an SRem, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifySRemInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse))
return V;
return nullptr;
}
Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifySRemInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for a URem, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyURemInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse))
return V;
return nullptr;
}
Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyURemInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
static Value *SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const Query &, unsigned) {
// undef % X -> undef (the undef could be a snan).
if (match(Op0, m_Undef()))
return Op0;
// X % undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// 0 % X -> 0
// Requires that NaNs are off (X could be zero) and signed zeroes are
// ignored (X could be positive or negative, so the output sign is unknown).
if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero()))
return Op0;
return nullptr;
}
Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyFRemInst(Op0, Op1, FMF, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Returns true if a shift by \c Amount always yields undef.
static bool isUndefShift(Value *Amount) {
Constant *C = dyn_cast<Constant>(Amount);
if (!C)
return false;
// X shift by undef -> undef because it may shift by the bitwidth.
if (isa<UndefValue>(C))
return true;
// Shifting by the bitwidth or more is undefined.
if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
if (CI->getValue().getLimitedValue() >=
CI->getType()->getScalarSizeInBits())
return true;
// If all lanes of a vector shift are undefined the whole shift is.
if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) {
for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; ++I)
if (!isUndefShift(C->getAggregateElement(I)))
return false;
return true;
}
return false;
}
/// Given operands for an Shl, LShr or AShr, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
const Query &Q, unsigned MaxRecurse) {
if (Constant *C0 = dyn_cast<Constant>(Op0))
if (Constant *C1 = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Opcode, C0, C1, Q.DL);
// 0 shift by X -> 0
if (match(Op0, m_Zero()))
return Op0;
// X shift by 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// Fold undefined shifts.
if (isUndefShift(Op1))
return UndefValue::get(Op0->getType());
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse))
return V;
// If any bits in the shift amount make that value greater than or equal to
// the number of bits in the type, the shift is undefined.
unsigned BitWidth = Op1->getType()->getScalarSizeInBits();
APInt KnownZero(BitWidth, 0);
APInt KnownOne(BitWidth, 0);
computeKnownBits(Op1, KnownZero, KnownOne, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (KnownOne.getLimitedValue() >= BitWidth)
return UndefValue::get(Op0->getType());
// If all valid bits in the shift amount are known zero, the first operand is
// unchanged.
unsigned NumValidShiftBits = Log2_32_Ceil(BitWidth);
APInt ShiftAmountMask = APInt::getLowBitsSet(BitWidth, NumValidShiftBits);
if ((KnownZero & ShiftAmountMask) == ShiftAmountMask)
return Op0;
return nullptr;
}
/// \brief Given operands for an Shl, LShr or AShr, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyRightShift(unsigned Opcode, Value *Op0, Value *Op1,
bool isExact, const Query &Q,
unsigned MaxRecurse) {
if (Value *V = SimplifyShift(Opcode, Op0, Op1, Q, MaxRecurse))
return V;
// X >> X -> 0
if (Op0 == Op1)
return Constant::getNullValue(Op0->getType());
// undef >> X -> 0
// undef >> X -> undef (if it's exact)
if (match(Op0, m_Undef()))
return isExact ? Op0 : Constant::getNullValue(Op0->getType());
// The low bit cannot be shifted out of an exact shift if it is set.
if (isExact) {
unsigned BitWidth = Op0->getType()->getScalarSizeInBits();
APInt Op0KnownZero(BitWidth, 0);
APInt Op0KnownOne(BitWidth, 0);
computeKnownBits(Op0, Op0KnownZero, Op0KnownOne, Q.DL, /*Depth=*/0, Q.AC,
Q.CxtI, Q.DT);
if (Op0KnownOne[0])
return Op0;
}
return nullptr;
}
/// Given operands for an Shl, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const Query &Q, unsigned MaxRecurse) {
if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, Q, MaxRecurse))
return V;
// undef << X -> 0
// undef << X -> undef if (if it's NSW/NUW)
if (match(Op0, m_Undef()))
return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType());
// (X >> A) << A -> X
Value *X;
if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
return X;
return nullptr;
}
Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const DataLayout &DL, const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for an LShr, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
const Query &Q, unsigned MaxRecurse) {
if (Value *V = SimplifyRightShift(Instruction::LShr, Op0, Op1, isExact, Q,
MaxRecurse))
return V;
// (X << A) >> A -> X
Value *X;
if (match(Op0, m_NUWShl(m_Value(X), m_Specific(Op1))))
return X;
return nullptr;
}
Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyLShrInst(Op0, Op1, isExact, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for an AShr, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
const Query &Q, unsigned MaxRecurse) {
if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q,
MaxRecurse))
return V;
// all ones >>a X -> all ones
if (match(Op0, m_AllOnes()))
return Op0;
// (X << A) >> A -> X
Value *X;
if (match(Op0, m_NSWShl(m_Value(X), m_Specific(Op1))))
return X;
// Arithmetic shifting an all-sign-bit value is a no-op.
unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (NumSignBits == Op0->getType()->getScalarSizeInBits())
return Op0;
return nullptr;
}
Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyAShrInst(Op0, Op1, isExact, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp,
ICmpInst *UnsignedICmp, bool IsAnd) {
Value *X, *Y;
ICmpInst::Predicate EqPred;
if (!match(ZeroICmp, m_ICmp(EqPred, m_Value(Y), m_Zero())) ||
!ICmpInst::isEquality(EqPred))
return nullptr;
ICmpInst::Predicate UnsignedPred;
if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) &&
ICmpInst::isUnsigned(UnsignedPred))
;
else if (match(UnsignedICmp,
m_ICmp(UnsignedPred, m_Value(Y), m_Specific(X))) &&
ICmpInst::isUnsigned(UnsignedPred))
UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
else
return nullptr;
// X < Y && Y != 0 --> X < Y
// X < Y || Y != 0 --> Y != 0
if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_NE)
return IsAnd ? UnsignedICmp : ZeroICmp;
// X >= Y || Y != 0 --> true
// X >= Y || Y == 0 --> X >= Y
if (UnsignedPred == ICmpInst::ICMP_UGE && !IsAnd) {
if (EqPred == ICmpInst::ICMP_NE)
return getTrue(UnsignedICmp->getType());
return UnsignedICmp;
}
// X < Y && Y == 0 --> false
if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ &&
IsAnd)
return getFalse(UnsignedICmp->getType());
return nullptr;
}
/// Simplify (and (icmp ...) (icmp ...)) to true when we can tell that the range
/// of possible values cannot be satisfied.
static Value *SimplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
ICmpInst::Predicate Pred0, Pred1;
ConstantInt *CI1, *CI2;
Value *V;
if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true))
return X;
if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_ConstantInt(CI1)),
m_ConstantInt(CI2))))
return nullptr;
if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Specific(CI1))))
return nullptr;
Type *ITy = Op0->getType();
auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
bool isNSW = AddInst->hasNoSignedWrap();
bool isNUW = AddInst->hasNoUnsignedWrap();
const APInt &CI1V = CI1->getValue();
const APInt &CI2V = CI2->getValue();
const APInt Delta = CI2V - CI1V;
if (CI1V.isStrictlyPositive()) {
if (Delta == 2) {
if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_SGT)
return getFalse(ITy);
if (Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT && isNSW)
return getFalse(ITy);
}
if (Delta == 1) {
if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_SGT)
return getFalse(ITy);
if (Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGT && isNSW)
return getFalse(ITy);
}
}
if (CI1V.getBoolValue() && isNUW) {
if (Delta == 2)
if (Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT)
return getFalse(ITy);
if (Delta == 1)
if (Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGT)
return getFalse(ITy);
}
return nullptr;
}
/// Given operands for an And, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyAndInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Instruction::And, CLHS, CRHS, Q.DL);
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X & undef -> 0
if (match(Op1, m_Undef()))
return Constant::getNullValue(Op0->getType());
// X & X = X
if (Op0 == Op1)
return Op0;
// X & 0 = 0
if (match(Op1, m_Zero()))
return Op1;
// X & -1 = X
if (match(Op1, m_AllOnes()))
return Op0;
// A & ~A = ~A & A = 0
if (match(Op0, m_Not(m_Specific(Op1))) ||
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getNullValue(Op0->getType());
// (A | ?) & A = A
Value *A = nullptr, *B = nullptr;
if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
(A == Op1 || B == Op1))
return Op1;
// A & (A | ?) = A
if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
(A == Op0 || B == Op0))
return Op0;
// A & (-A) = A if A is a power of two or zero.
if (match(Op0, m_Neg(m_Specific(Op1))) ||
match(Op1, m_Neg(m_Specific(Op0)))) {
if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
Q.DT))
return Op0;
if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
Q.DT))
return Op1;
}
if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
if (Value *V = SimplifyAndOfICmps(ICILHS, ICIRHS))
return V;
if (Value *V = SimplifyAndOfICmps(ICIRHS, ICILHS))
return V;
}
}
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q,
MaxRecurse))
return V;
// And distributes over Or. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
Q, MaxRecurse))
return V;
// And distributes over Xor. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
Q, MaxRecurse))
return V;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q,
MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q,
MaxRecurse))
return V;
return nullptr;
}
Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyAndInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Simplify (or (icmp ...) (icmp ...)) to true when we can tell that the union
/// contains all possible values.
static Value *SimplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1) {
ICmpInst::Predicate Pred0, Pred1;
ConstantInt *CI1, *CI2;
Value *V;
if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false))
return X;
if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_ConstantInt(CI1)),
m_ConstantInt(CI2))))
return nullptr;
if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Specific(CI1))))
return nullptr;
Type *ITy = Op0->getType();
auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
bool isNSW = AddInst->hasNoSignedWrap();
bool isNUW = AddInst->hasNoUnsignedWrap();
const APInt &CI1V = CI1->getValue();
const APInt &CI2V = CI2->getValue();
const APInt Delta = CI2V - CI1V;
if (CI1V.isStrictlyPositive()) {
if (Delta == 2) {
if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_SLE)
return getTrue(ITy);
if (Pred0 == ICmpInst::ICMP_SGE && Pred1 == ICmpInst::ICMP_SLE && isNSW)
return getTrue(ITy);
}
if (Delta == 1) {
if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_SLE)
return getTrue(ITy);
if (Pred0 == ICmpInst::ICMP_SGT && Pred1 == ICmpInst::ICMP_SLE && isNSW)
return getTrue(ITy);
}
}
if (CI1V.getBoolValue() && isNUW) {
if (Delta == 2)
if (Pred0 == ICmpInst::ICMP_UGE && Pred1 == ICmpInst::ICMP_ULE)
return getTrue(ITy);
if (Delta == 1)
if (Pred0 == ICmpInst::ICMP_UGT && Pred1 == ICmpInst::ICMP_ULE)
return getTrue(ITy);
}
return nullptr;
}
/// Given operands for an Or, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyOrInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Instruction::Or, CLHS, CRHS, Q.DL);
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// X | undef -> -1
if (match(Op1, m_Undef()))
return Constant::getAllOnesValue(Op0->getType());
// X | X = X
if (Op0 == Op1)
return Op0;
// X | 0 = X
if (match(Op1, m_Zero()))
return Op0;
// X | -1 = -1
if (match(Op1, m_AllOnes()))
return Op1;
// A | ~A = ~A | A = -1
if (match(Op0, m_Not(m_Specific(Op1))) ||
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getAllOnesValue(Op0->getType());
// (A & ?) | A = A
Value *A = nullptr, *B = nullptr;
if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
(A == Op1 || B == Op1))
return Op1;
// A | (A & ?) = A
if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
(A == Op0 || B == Op0))
return Op0;
// ~(A & ?) | A = -1
if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
(A == Op1 || B == Op1))
return Constant::getAllOnesValue(Op1->getType());
// A | ~(A & ?) = -1
if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
(A == Op0 || B == Op0))
return Constant::getAllOnesValue(Op0->getType());
if (auto *ICILHS = dyn_cast<ICmpInst>(Op0)) {
if (auto *ICIRHS = dyn_cast<ICmpInst>(Op1)) {
if (Value *V = SimplifyOrOfICmps(ICILHS, ICIRHS))
return V;
if (Value *V = SimplifyOrOfICmps(ICIRHS, ICILHS))
return V;
}
}
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q,
MaxRecurse))
return V;
// Or distributes over And. Try some generic simplifications based on this.
if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q,
MaxRecurse))
return V;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
MaxRecurse))
return V;
// (A & C)|(B & D)
Value *C = nullptr, *D = nullptr;
if (match(Op0, m_And(m_Value(A), m_Value(C))) &&
match(Op1, m_And(m_Value(B), m_Value(D)))) {
ConstantInt *C1 = dyn_cast<ConstantInt>(C);
ConstantInt *C2 = dyn_cast<ConstantInt>(D);
if (C1 && C2 && (C1->getValue() == ~C2->getValue())) {
// (A & C1)|(B & C2)
// If we have: ((V + N) & C1) | (V & C2)
// .. and C2 = ~C1 and C2 is 0+1+ and (N & C2) == 0
// replace with V+N.
Value *V1, *V2;
if ((C2->getValue() & (C2->getValue() + 1)) == 0 && // C2 == 0+1+
match(A, m_Add(m_Value(V1), m_Value(V2)))) {
// Add commutes, try both ways.
if (V1 == B &&
MaskedValueIsZero(V2, C2->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return A;
if (V2 == B &&
MaskedValueIsZero(V1, C2->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return A;
}
// Or commutes, try both ways.
if ((C1->getValue() & (C1->getValue() + 1)) == 0 &&
match(B, m_Add(m_Value(V1), m_Value(V2)))) {
// Add commutes, try both ways.
if (V1 == A &&
MaskedValueIsZero(V2, C1->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return B;
if (V2 == A &&
MaskedValueIsZero(V1, C1->getValue(), Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return B;
}
}
}
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, Q, MaxRecurse))
return V;
return nullptr;
}
Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyOrInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for a Xor, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyXorInst(Value *Op0, Value *Op1, const Query &Q,
unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Instruction::Xor, CLHS, CRHS, Q.DL);
// Canonicalize the constant to the RHS.
std::swap(Op0, Op1);
}
// A ^ undef -> undef
if (match(Op1, m_Undef()))
return Op1;
// A ^ 0 = A
if (match(Op1, m_Zero()))
return Op0;
// A ^ A = 0
if (Op0 == Op1)
return Constant::getNullValue(Op0->getType());
// A ^ ~A = ~A ^ A = -1
if (match(Op0, m_Not(m_Specific(Op1))) ||
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getAllOnesValue(Op0->getType());
// Try some generic simplifications for associative operations.
if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q,
MaxRecurse))
return V;
// Threading Xor over selects and phi nodes is pointless, so don't bother.
// Threading over the select in "A ^ select(cond, B, C)" means evaluating
// "A^B" and "A^C" and seeing if they are equal; but they are equal if and
// only if B and C are equal. If B and C are equal then (since we assume
// that operands have already been simplified) "select(cond, B, C)" should
// have been simplified to the common value of B and C already. Analysing
// "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
// for threading over phi nodes.
return nullptr;
}
Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyXorInst(Op0, Op1, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
static Type *GetCompareTy(Value *Op) {
return CmpInst::makeCmpResultType(Op->getType());
}
/// Rummage around inside V looking for something equivalent to the comparison
/// "LHS Pred RHS". Return such a value if found, otherwise return null.
/// Helper function for analyzing max/min idioms.
static Value *ExtractEquivalentCondition(Value *V, CmpInst::Predicate Pred,
Value *LHS, Value *RHS) {
SelectInst *SI = dyn_cast<SelectInst>(V);
if (!SI)
return nullptr;
CmpInst *Cmp = dyn_cast<CmpInst>(SI->getCondition());
if (!Cmp)
return nullptr;
Value *CmpLHS = Cmp->getOperand(0), *CmpRHS = Cmp->getOperand(1);
if (Pred == Cmp->getPredicate() && LHS == CmpLHS && RHS == CmpRHS)
return Cmp;
if (Pred == CmpInst::getSwappedPredicate(Cmp->getPredicate()) &&
LHS == CmpRHS && RHS == CmpLHS)
return Cmp;
return nullptr;
}
// A significant optimization not implemented here is assuming that alloca
// addresses are not equal to incoming argument values. They don't *alias*,
// as we say, but that doesn't mean they aren't equal, so we take a
// conservative approach.
//
// This is inspired in part by C++11 5.10p1:
// "Two pointers of the same type compare equal if and only if they are both
// null, both point to the same function, or both represent the same
// address."
//
// This is pretty permissive.
//
// It's also partly due to C11 6.5.9p6:
// "Two pointers compare equal if and only if both are null pointers, both are
// pointers to the same object (including a pointer to an object and a
// subobject at its beginning) or function, both are pointers to one past the
// last element of the same array object, or one is a pointer to one past the
// end of one array object and the other is a pointer to the start of a
// different array object that happens to immediately follow the first array
// object in the address space.)
//
// C11's version is more restrictive, however there's no reason why an argument
// couldn't be a one-past-the-end value for a stack object in the caller and be
// equal to the beginning of a stack object in the callee.
//
// If the C and C++ standards are ever made sufficiently restrictive in this
// area, it may be possible to update LLVM's semantics accordingly and reinstate
// this optimization.
static Constant *
computePointerICmp(const DataLayout &DL, const TargetLibraryInfo *TLI,
const DominatorTree *DT, CmpInst::Predicate Pred,
const Instruction *CxtI, Value *LHS, Value *RHS) {
// First, skip past any trivial no-ops.
LHS = LHS->stripPointerCasts();
RHS = RHS->stripPointerCasts();
// A non-null pointer is not equal to a null pointer.
if (llvm::isKnownNonNull(LHS, TLI) && isa<ConstantPointerNull>(RHS) &&
(Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE))
return ConstantInt::get(GetCompareTy(LHS),
!CmpInst::isTrueWhenEqual(Pred));
// We can only fold certain predicates on pointer comparisons.
switch (Pred) {
default:
return nullptr;
// Equality comaprisons are easy to fold.
case CmpInst::ICMP_EQ:
case CmpInst::ICMP_NE:
break;
// We can only handle unsigned relational comparisons because 'inbounds' on
// a GEP only protects against unsigned wrapping.
case CmpInst::ICMP_UGT:
case CmpInst::ICMP_UGE:
case CmpInst::ICMP_ULT:
case CmpInst::ICMP_ULE:
// However, we have to switch them to their signed variants to handle
// negative indices from the base pointer.
Pred = ICmpInst::getSignedPredicate(Pred);
break;
}
// Strip off any constant offsets so that we can reason about them.
// It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets
// here and compare base addresses like AliasAnalysis does, however there are
// numerous hazards. AliasAnalysis and its utilities rely on special rules
// governing loads and stores which don't apply to icmps. Also, AliasAnalysis
// doesn't need to guarantee pointer inequality when it says NoAlias.
Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS);
Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS);
// If LHS and RHS are related via constant offsets to the same base
// value, we can replace it with an icmp which just compares the offsets.
if (LHS == RHS)
return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset);
// Various optimizations for (in)equality comparisons.
if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) {
// Different non-empty allocations that exist at the same time have
// different addresses (if the program can tell). Global variables always
// exist, so they always exist during the lifetime of each other and all
// allocas. Two different allocas usually have different addresses...
//
// However, if there's an @llvm.stackrestore dynamically in between two
// allocas, they may have the same address. It's tempting to reduce the
// scope of the problem by only looking at *static* allocas here. That would
// cover the majority of allocas while significantly reducing the likelihood
// of having an @llvm.stackrestore pop up in the middle. However, it's not
// actually impossible for an @llvm.stackrestore to pop up in the middle of
// an entry block. Also, if we have a block that's not attached to a
// function, we can't tell if it's "static" under the current definition.
// Theoretically, this problem could be fixed by creating a new kind of
// instruction kind specifically for static allocas. Such a new instruction
// could be required to be at the top of the entry block, thus preventing it
// from being subject to a @llvm.stackrestore. Instcombine could even
// convert regular allocas into these special allocas. It'd be nifty.
// However, until then, this problem remains open.
//
// So, we'll assume that two non-empty allocas have different addresses
// for now.
//
// With all that, if the offsets are within the bounds of their allocations
// (and not one-past-the-end! so we can't use inbounds!), and their
// allocations aren't the same, the pointers are not equal.
//
// Note that it's not necessary to check for LHS being a global variable
// address, due to canonicalization and constant folding.
if (isa<AllocaInst>(LHS) &&
(isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) {
ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset);
ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset);
uint64_t LHSSize, RHSSize;
if (LHSOffsetCI && RHSOffsetCI &&
getObjectSize(LHS, LHSSize, DL, TLI) &&
getObjectSize(RHS, RHSSize, DL, TLI)) {
const APInt &LHSOffsetValue = LHSOffsetCI->getValue();
const APInt &RHSOffsetValue = RHSOffsetCI->getValue();
if (!LHSOffsetValue.isNegative() &&
!RHSOffsetValue.isNegative() &&
LHSOffsetValue.ult(LHSSize) &&
RHSOffsetValue.ult(RHSSize)) {
return ConstantInt::get(GetCompareTy(LHS),
!CmpInst::isTrueWhenEqual(Pred));
}
}
// Repeat the above check but this time without depending on DataLayout
// or being able to compute a precise size.
if (!cast<PointerType>(LHS->getType())->isEmptyTy() &&
!cast<PointerType>(RHS->getType())->isEmptyTy() &&
LHSOffset->isNullValue() &&
RHSOffset->isNullValue())
return ConstantInt::get(GetCompareTy(LHS),
!CmpInst::isTrueWhenEqual(Pred));
}
// Even if an non-inbounds GEP occurs along the path we can still optimize
// equality comparisons concerning the result. We avoid walking the whole
// chain again by starting where the last calls to
// stripAndComputeConstantOffsets left off and accumulate the offsets.
Constant *LHSNoBound = stripAndComputeConstantOffsets(DL, LHS, true);
Constant *RHSNoBound = stripAndComputeConstantOffsets(DL, RHS, true);
if (LHS == RHS)
return ConstantExpr::getICmp(Pred,
ConstantExpr::getAdd(LHSOffset, LHSNoBound),
ConstantExpr::getAdd(RHSOffset, RHSNoBound));
// If one side of the equality comparison must come from a noalias call
// (meaning a system memory allocation function), and the other side must
// come from a pointer that cannot overlap with dynamically-allocated
// memory within the lifetime of the current function (allocas, byval
// arguments, globals), then determine the comparison result here.
SmallVector<Value *, 8> LHSUObjs, RHSUObjs;
GetUnderlyingObjects(LHS, LHSUObjs, DL);
GetUnderlyingObjects(RHS, RHSUObjs, DL);
// Is the set of underlying objects all noalias calls?
auto IsNAC = [](SmallVectorImpl<Value *> &Objects) {
return std::all_of(Objects.begin(), Objects.end(), isNoAliasCall);
};
// Is the set of underlying objects all things which must be disjoint from
// noalias calls. For allocas, we consider only static ones (dynamic
// allocas might be transformed into calls to malloc not simultaneously
// live with the compared-to allocation). For globals, we exclude symbols
// that might be resolve lazily to symbols in another dynamically-loaded
// library (and, thus, could be malloc'ed by the implementation).
auto IsAllocDisjoint = [](SmallVectorImpl<Value *> &Objects) {
return std::all_of(Objects.begin(), Objects.end(), [](Value *V) {
if (const AllocaInst *AI = dyn_cast<AllocaInst>(V))
return AI->getParent() && AI->getFunction() && AI->isStaticAlloca();
if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
return (GV->hasLocalLinkage() || GV->hasHiddenVisibility() ||
GV->hasProtectedVisibility() || GV->hasUnnamedAddr()) &&
!GV->isThreadLocal();
if (const Argument *A = dyn_cast<Argument>(V))
return A->hasByValAttr();
return false;
});
};
if ((IsNAC(LHSUObjs) && IsAllocDisjoint(RHSUObjs)) ||
(IsNAC(RHSUObjs) && IsAllocDisjoint(LHSUObjs)))
return ConstantInt::get(GetCompareTy(LHS),
!CmpInst::isTrueWhenEqual(Pred));
// Fold comparisons for non-escaping pointer even if the allocation call
// cannot be elided. We cannot fold malloc comparison to null. Also, the
// dynamic allocation call could be either of the operands.
Value *MI = nullptr;
if (isAllocLikeFn(LHS, TLI) && llvm::isKnownNonNullAt(RHS, CxtI, DT, TLI))
MI = LHS;
else if (isAllocLikeFn(RHS, TLI) &&
llvm::isKnownNonNullAt(LHS, CxtI, DT, TLI))
MI = RHS;
// FIXME: We should also fold the compare when the pointer escapes, but the
// compare dominates the pointer escape
if (MI && !PointerMayBeCaptured(MI, true, true))
return ConstantInt::get(GetCompareTy(LHS),
CmpInst::isFalseWhenEqual(Pred));
}
// Otherwise, fail.
return nullptr;
}
/// Given operands for an ICmpInst, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const Query &Q, unsigned MaxRecurse) {
CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!");
if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
if (Constant *CRHS = dyn_cast<Constant>(RHS))
return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
// If we have a constant, make sure it is on the RHS.
std::swap(LHS, RHS);
Pred = CmpInst::getSwappedPredicate(Pred);
}
Type *ITy = GetCompareTy(LHS); // The return type.
Type *OpTy = LHS->getType(); // The operand type.
// icmp X, X -> true/false
// X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
// because X could be 0.
if (LHS == RHS || isa<UndefValue>(RHS))
return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
// Special case logic when the operands have i1 type.
if (OpTy->getScalarType()->isIntegerTy(1)) {
switch (Pred) {
default: break;
case ICmpInst::ICMP_EQ:
// X == 1 -> X
if (match(RHS, m_One()))
return LHS;
break;
case ICmpInst::ICMP_NE:
// X != 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_UGT:
// X >u 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_UGE: {
// X >=u 1 -> X
if (match(RHS, m_One()))
return LHS;
if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false))
return getTrue(ITy);
break;
}
case ICmpInst::ICMP_SGE: {
/// For signed comparison, the values for an i1 are 0 and -1
/// respectively. This maps into a truth table of:
/// LHS | RHS | LHS >=s RHS | LHS implies RHS
/// 0 | 0 | 1 (0 >= 0) | 1
/// 0 | 1 | 1 (0 >= -1) | 1
/// 1 | 0 | 0 (-1 >= 0) | 0
/// 1 | 1 | 1 (-1 >= -1) | 1
if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
return getTrue(ITy);
break;
}
case ICmpInst::ICMP_SLT:
// X <s 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_SLE:
// X <=s -1 -> X
if (match(RHS, m_One()))
return LHS;
break;
case ICmpInst::ICMP_ULE: {
if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
return getTrue(ITy);
break;
}
}
}
// If we are comparing with zero then try hard since this is a common case.
if (match(RHS, m_Zero())) {
bool LHSKnownNonNegative, LHSKnownNegative;
switch (Pred) {
default: llvm_unreachable("Unknown ICmp predicate!");
case ICmpInst::ICMP_ULT:
return getFalse(ITy);
case ICmpInst::ICMP_UGE:
return getTrue(ITy);
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_ULE:
if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getFalse(ITy);
break;
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_UGT:
if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getTrue(ITy);
break;
case ICmpInst::ICMP_SLT:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getTrue(ITy);
if (LHSKnownNonNegative)
return getFalse(ITy);
break;
case ICmpInst::ICMP_SLE:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getTrue(ITy);
if (LHSKnownNonNegative &&
isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getFalse(ITy);
break;
case ICmpInst::ICMP_SGE:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getFalse(ITy);
if (LHSKnownNonNegative)
return getTrue(ITy);
break;
case ICmpInst::ICMP_SGT:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getFalse(ITy);
if (LHSKnownNonNegative &&
isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getTrue(ITy);
break;
}
}
// See if we are doing a comparison with a constant integer.
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
// Rule out tautological comparisons (eg., ult 0 or uge 0).
ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
if (RHS_CR.isEmptySet())
return ConstantInt::getFalse(CI->getContext());
if (RHS_CR.isFullSet())
return ConstantInt::getTrue(CI->getContext());
// Many binary operators with constant RHS have easy to compute constant
// range. Use them to check whether the comparison is a tautology.
unsigned Width = CI->getBitWidth();
APInt Lower = APInt(Width, 0);
APInt Upper = APInt(Width, 0);
ConstantInt *CI2;
if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
// 'urem x, CI2' produces [0, CI2).
Upper = CI2->getValue();
} else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
// 'srem x, CI2' produces (-|CI2|, |CI2|).
Upper = CI2->getValue().abs();
Lower = (-Upper) + 1;
} else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
// 'udiv CI2, x' produces [0, CI2].
Upper = CI2->getValue() + 1;
} else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
// 'udiv x, CI2' produces [0, UINT_MAX / CI2].
APInt NegOne = APInt::getAllOnesValue(Width);
if (!CI2->isZero())
Upper = NegOne.udiv(CI2->getValue()) + 1;
} else if (match(LHS, m_SDiv(m_ConstantInt(CI2), m_Value()))) {
if (CI2->isMinSignedValue()) {
// 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2].
Lower = CI2->getValue();
Upper = Lower.lshr(1) + 1;
} else {
// 'sdiv CI2, x' produces [-|CI2|, |CI2|].
Upper = CI2->getValue().abs() + 1;
Lower = (-Upper) + 1;
}
} else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
APInt IntMin = APInt::getSignedMinValue(Width);
APInt IntMax = APInt::getSignedMaxValue(Width);
APInt Val = CI2->getValue();
if (Val.isAllOnesValue()) {
// 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX]
// where CI2 != -1 and CI2 != 0 and CI2 != 1
Lower = IntMin + 1;
Upper = IntMax + 1;
} else if (Val.countLeadingZeros() < Width - 1) {
// 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]
// where CI2 != -1 and CI2 != 0 and CI2 != 1
Lower = IntMin.sdiv(Val);
Upper = IntMax.sdiv(Val);
if (Lower.sgt(Upper))
std::swap(Lower, Upper);
Upper = Upper + 1;
assert(Upper != Lower && "Upper part of range has wrapped!");
}
} else if (match(LHS, m_NUWShl(m_ConstantInt(CI2), m_Value()))) {
// 'shl nuw CI2, x' produces [CI2, CI2 << CLZ(CI2)]
Lower = CI2->getValue();
Upper = Lower.shl(Lower.countLeadingZeros()) + 1;
} else if (match(LHS, m_NSWShl(m_ConstantInt(CI2), m_Value()))) {
if (CI2->isNegative()) {
// 'shl nsw CI2, x' produces [CI2 << CLO(CI2)-1, CI2]
unsigned ShiftAmount = CI2->getValue().countLeadingOnes() - 1;
Lower = CI2->getValue().shl(ShiftAmount);
Upper = CI2->getValue() + 1;
} else {
// 'shl nsw CI2, x' produces [CI2, CI2 << CLZ(CI2)-1]
unsigned ShiftAmount = CI2->getValue().countLeadingZeros() - 1;
Lower = CI2->getValue();
Upper = CI2->getValue().shl(ShiftAmount) + 1;
}
} else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
// 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
APInt NegOne = APInt::getAllOnesValue(Width);
if (CI2->getValue().ult(Width))
Upper = NegOne.lshr(CI2->getValue()) + 1;
} else if (match(LHS, m_LShr(m_ConstantInt(CI2), m_Value()))) {
// 'lshr CI2, x' produces [CI2 >> (Width-1), CI2].
unsigned ShiftAmount = Width - 1;
if (!CI2->isZero() && cast<BinaryOperator>(LHS)->isExact())
ShiftAmount = CI2->getValue().countTrailingZeros();
Lower = CI2->getValue().lshr(ShiftAmount);
Upper = CI2->getValue() + 1;
} else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
// 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
APInt IntMin = APInt::getSignedMinValue(Width);
APInt IntMax = APInt::getSignedMaxValue(Width);
if (CI2->getValue().ult(Width)) {
Lower = IntMin.ashr(CI2->getValue());
Upper = IntMax.ashr(CI2->getValue()) + 1;
}
} else if (match(LHS, m_AShr(m_ConstantInt(CI2), m_Value()))) {
unsigned ShiftAmount = Width - 1;
if (!CI2->isZero() && cast<BinaryOperator>(LHS)->isExact())
ShiftAmount = CI2->getValue().countTrailingZeros();
if (CI2->isNegative()) {
// 'ashr CI2, x' produces [CI2, CI2 >> (Width-1)]
Lower = CI2->getValue();
Upper = CI2->getValue().ashr(ShiftAmount) + 1;
} else {
// 'ashr CI2, x' produces [CI2 >> (Width-1), CI2]
Lower = CI2->getValue().ashr(ShiftAmount);
Upper = CI2->getValue() + 1;
}
} else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
// 'or x, CI2' produces [CI2, UINT_MAX].
Lower = CI2->getValue();
} else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
// 'and x, CI2' produces [0, CI2].
Upper = CI2->getValue() + 1;
} else if (match(LHS, m_NUWAdd(m_Value(), m_ConstantInt(CI2)))) {
// 'add nuw x, CI2' produces [CI2, UINT_MAX].
Lower = CI2->getValue();
}
ConstantRange LHS_CR = Lower != Upper ? ConstantRange(Lower, Upper)
: ConstantRange(Width, true);
if (auto *I = dyn_cast<Instruction>(LHS))
if (auto *Ranges = I->getMetadata(LLVMContext::MD_range))
LHS_CR = LHS_CR.intersectWith(getConstantRangeFromMetadata(*Ranges));
if (!LHS_CR.isFullSet()) {
if (RHS_CR.contains(LHS_CR))
return ConstantInt::getTrue(RHS->getContext());
if (RHS_CR.inverse().contains(LHS_CR))
return ConstantInt::getFalse(RHS->getContext());
}
}
// If both operands have range metadata, use the metadata
// to simplify the comparison.
if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) {
auto RHS_Instr = dyn_cast<Instruction>(RHS);
auto LHS_Instr = dyn_cast<Instruction>(LHS);
if (RHS_Instr->getMetadata(LLVMContext::MD_range) &&
LHS_Instr->getMetadata(LLVMContext::MD_range)) {
auto RHS_CR = getConstantRangeFromMetadata(
*RHS_Instr->getMetadata(LLVMContext::MD_range));
auto LHS_CR = getConstantRangeFromMetadata(
*LHS_Instr->getMetadata(LLVMContext::MD_range));
auto Satisfied_CR = ConstantRange::makeSatisfyingICmpRegion(Pred, RHS_CR);
if (Satisfied_CR.contains(LHS_CR))
return ConstantInt::getTrue(RHS->getContext());
auto InversedSatisfied_CR = ConstantRange::makeSatisfyingICmpRegion(
CmpInst::getInversePredicate(Pred), RHS_CR);
if (InversedSatisfied_CR.contains(LHS_CR))
return ConstantInt::getFalse(RHS->getContext());
}
}
// Compare of cast, for example (zext X) != 0 -> X != 0
if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
Instruction *LI = cast<CastInst>(LHS);
Value *SrcOp = LI->getOperand(0);
Type *SrcTy = SrcOp->getType();
Type *DstTy = LI->getType();
// Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
// if the integer type is the same size as the pointer type.
if (MaxRecurse && isa<PtrToIntInst>(LI) &&
Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) {
if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
// Transfer the cast to the constant.
if (Value *V = SimplifyICmpInst(Pred, SrcOp,
ConstantExpr::getIntToPtr(RHSC, SrcTy),
Q, MaxRecurse-1))
return V;
} else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
if (RI->getOperand(0)->getType() == SrcTy)
// Compare without the cast.
if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
Q, MaxRecurse-1))
return V;
}
}
if (isa<ZExtInst>(LHS)) {
// Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
// same type.
if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
// Compare X and Y. Note that signed predicates become unsigned.
if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
SrcOp, RI->getOperand(0), Q,
MaxRecurse-1))
return V;
}
// Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
// too. If not, then try to deduce the result of the comparison.
else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
// Compute the constant that would happen if we truncated to SrcTy then
// reextended to DstTy.
Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
// If the re-extended constant didn't change then this is effectively
// also a case of comparing two zero-extended values.
if (RExt == CI && MaxRecurse)
if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
SrcOp, Trunc, Q, MaxRecurse-1))
return V;
// Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
// there. Use this to work out the result of the comparison.
if (RExt != CI) {
switch (Pred) {
default: llvm_unreachable("Unknown ICmp predicate!");
// LHS <u RHS.
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
return ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
return ConstantInt::getTrue(CI->getContext());
// LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
// is non-negative then LHS <s RHS.
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
return CI->getValue().isNegative() ?
ConstantInt::getTrue(CI->getContext()) :
ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
return CI->getValue().isNegative() ?
ConstantInt::getFalse(CI->getContext()) :
ConstantInt::getTrue(CI->getContext());
}
}
}
}
if (isa<SExtInst>(LHS)) {
// Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
// same type.
if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
// Compare X and Y. Note that the predicate does not change.
if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
Q, MaxRecurse-1))
return V;
}
// Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
// too. If not, then try to deduce the result of the comparison.
else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
// Compute the constant that would happen if we truncated to SrcTy then
// reextended to DstTy.
Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
// If the re-extended constant didn't change then this is effectively
// also a case of comparing two sign-extended values.
if (RExt == CI && MaxRecurse)
if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1))
return V;
// Otherwise the upper bits of LHS are all equal, while RHS has varying
// bits there. Use this to work out the result of the comparison.
if (RExt != CI) {
switch (Pred) {
default: llvm_unreachable("Unknown ICmp predicate!");
case ICmpInst::ICMP_EQ:
return ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_NE:
return ConstantInt::getTrue(CI->getContext());
// If RHS is non-negative then LHS <s RHS. If RHS is negative then
// LHS >s RHS.
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
return CI->getValue().isNegative() ?
ConstantInt::getTrue(CI->getContext()) :
ConstantInt::getFalse(CI->getContext());
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
return CI->getValue().isNegative() ?
ConstantInt::getFalse(CI->getContext()) :
ConstantInt::getTrue(CI->getContext());
// If LHS is non-negative then LHS <u RHS. If LHS is negative then
// LHS >u RHS.
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
// Comparison is true iff the LHS <s 0.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
Constant::getNullValue(SrcTy),
Q, MaxRecurse-1))
return V;
break;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
// Comparison is true iff the LHS >=s 0.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
Constant::getNullValue(SrcTy),
Q, MaxRecurse-1))
return V;
break;
}
}
}
}
}
// icmp eq|ne X, Y -> false|true if X != Y
if ((Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE) &&
isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT)) {
LLVMContext &Ctx = LHS->getType()->getContext();
return Pred == ICmpInst::ICMP_NE ?
ConstantInt::getTrue(Ctx) : ConstantInt::getFalse(Ctx);
}
// Special logic for binary operators.
BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
if (MaxRecurse && (LBO || RBO)) {
// Analyze the case when either LHS or RHS is an add instruction.
Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
// LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
if (LBO && LBO->getOpcode() == Instruction::Add) {
A = LBO->getOperand(0); B = LBO->getOperand(1);
NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
(CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
(CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
}
if (RBO && RBO->getOpcode() == Instruction::Add) {
C = RBO->getOperand(0); D = RBO->getOperand(1);
NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
(CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
(CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
}
// icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
if ((A == RHS || B == RHS) && NoLHSWrapProblem)
if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
Constant::getNullValue(RHS->getType()),
Q, MaxRecurse-1))
return V;
// icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
if ((C == LHS || D == LHS) && NoRHSWrapProblem)
if (Value *V = SimplifyICmpInst(Pred,
Constant::getNullValue(LHS->getType()),
C == LHS ? D : C, Q, MaxRecurse-1))
return V;
// icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
if (A && C && (A == C || A == D || B == C || B == D) &&
NoLHSWrapProblem && NoRHSWrapProblem) {
// Determine Y and Z in the form icmp (X+Y), (X+Z).
Value *Y, *Z;
if (A == C) {
// C + B == C + D -> B == D
Y = B;
Z = D;
} else if (A == D) {
// D + B == C + D -> B == C
Y = B;
Z = C;
} else if (B == C) {
// A + C == C + D -> A == D
Y = A;
Z = D;
} else {
assert(B == D);
// A + D == C + D -> A == C
Y = A;
Z = C;
}
if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse-1))
return V;
}
}
{
Value *Y = nullptr;
// icmp pred (or X, Y), X
if (LBO && match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) {
if (Pred == ICmpInst::ICMP_ULT)
return getFalse(ITy);
if (Pred == ICmpInst::ICMP_UGE)
return getTrue(ITy);
if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) {
bool RHSKnownNonNegative, RHSKnownNegative;
bool YKnownNonNegative, YKnownNegative;
ComputeSignBit(RHS, RHSKnownNonNegative, RHSKnownNegative, Q.DL, 0,
Q.AC, Q.CxtI, Q.DT);
ComputeSignBit(Y, YKnownNonNegative, YKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (RHSKnownNonNegative && YKnownNegative)
return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy);
if (RHSKnownNegative || YKnownNonNegative)
return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy);
}
}
// icmp pred X, (or X, Y)
if (RBO && match(RBO, m_c_Or(m_Value(Y), m_Specific(LHS)))) {
if (Pred == ICmpInst::ICMP_ULE)
return getTrue(ITy);
if (Pred == ICmpInst::ICMP_UGT)
return getFalse(ITy);
if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLE) {
bool LHSKnownNonNegative, LHSKnownNegative;
bool YKnownNonNegative, YKnownNegative;
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0,
Q.AC, Q.CxtI, Q.DT);
ComputeSignBit(Y, YKnownNonNegative, YKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNonNegative && YKnownNegative)
return Pred == ICmpInst::ICMP_SGT ? getTrue(ITy) : getFalse(ITy);
if (LHSKnownNegative || YKnownNonNegative)
return Pred == ICmpInst::ICMP_SGT ? getFalse(ITy) : getTrue(ITy);
}
}
}
// icmp pred (and X, Y), X
if (LBO && match(LBO, m_CombineOr(m_And(m_Value(), m_Specific(RHS)),
m_And(m_Specific(RHS), m_Value())))) {
if (Pred == ICmpInst::ICMP_UGT)
return getFalse(ITy);
if (Pred == ICmpInst::ICMP_ULE)
return getTrue(ITy);
}
// icmp pred X, (and X, Y)
if (RBO && match(RBO, m_CombineOr(m_And(m_Value(), m_Specific(LHS)),
m_And(m_Specific(LHS), m_Value())))) {
if (Pred == ICmpInst::ICMP_UGE)
return getTrue(ITy);
if (Pred == ICmpInst::ICMP_ULT)
return getFalse(ITy);
}
// 0 - (zext X) pred C
if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) {
if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) {
if (RHSC->getValue().isStrictlyPositive()) {
if (Pred == ICmpInst::ICMP_SLT)
return ConstantInt::getTrue(RHSC->getContext());
if (Pred == ICmpInst::ICMP_SGE)
return ConstantInt::getFalse(RHSC->getContext());
if (Pred == ICmpInst::ICMP_EQ)
return ConstantInt::getFalse(RHSC->getContext());
if (Pred == ICmpInst::ICMP_NE)
return ConstantInt::getTrue(RHSC->getContext());
}
if (RHSC->getValue().isNonNegative()) {
if (Pred == ICmpInst::ICMP_SLE)
return ConstantInt::getTrue(RHSC->getContext());
if (Pred == ICmpInst::ICMP_SGT)
return ConstantInt::getFalse(RHSC->getContext());
}
}
}
// icmp pred (urem X, Y), Y
if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
bool KnownNonNegative, KnownNegative;
switch (Pred) {
default:
break;
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (!KnownNonNegative)
break;
// fall-through
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
return getFalse(ITy);
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
ComputeSignBit(RHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (!KnownNonNegative)
break;
// fall-through
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
return getTrue(ITy);
}
}
// icmp pred X, (urem Y, X)
if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
bool KnownNonNegative, KnownNegative;
switch (Pred) {
default:
break;
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (!KnownNonNegative)
break;
// fall-through
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
return getTrue(ITy);
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE:
ComputeSignBit(LHS, KnownNonNegative, KnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (!KnownNonNegative)
break;
// fall-through
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
return getFalse(ITy);
}
}
// x >> y <=u x
// x udiv y <=u x.
if (LBO && (match(LBO, m_LShr(m_Specific(RHS), m_Value())) ||
match(LBO, m_UDiv(m_Specific(RHS), m_Value())))) {
// icmp pred (X op Y), X
if (Pred == ICmpInst::ICMP_UGT)
return getFalse(ITy);
if (Pred == ICmpInst::ICMP_ULE)
return getTrue(ITy);
}
// handle:
// CI2 << X == CI
// CI2 << X != CI
//
// where CI2 is a power of 2 and CI isn't
if (auto *CI = dyn_cast<ConstantInt>(RHS)) {
const APInt *CI2Val, *CIVal = &CI->getValue();
if (LBO && match(LBO, m_Shl(m_APInt(CI2Val), m_Value())) &&
CI2Val->isPowerOf2()) {
if (!CIVal->isPowerOf2()) {
// CI2 << X can equal zero in some circumstances,
// this simplification is unsafe if CI is zero.
//
// We know it is safe if:
// - The shift is nsw, we can't shift out the one bit.
// - The shift is nuw, we can't shift out the one bit.
// - CI2 is one
// - CI isn't zero
if (LBO->hasNoSignedWrap() || LBO->hasNoUnsignedWrap() ||
*CI2Val == 1 || !CI->isZero()) {
if (Pred == ICmpInst::ICMP_EQ)
return ConstantInt::getFalse(RHS->getContext());
if (Pred == ICmpInst::ICMP_NE)
return ConstantInt::getTrue(RHS->getContext());
}
}
if (CIVal->isSignBit() && *CI2Val == 1) {
if (Pred == ICmpInst::ICMP_UGT)
return ConstantInt::getFalse(RHS->getContext());
if (Pred == ICmpInst::ICMP_ULE)
return ConstantInt::getTrue(RHS->getContext());
}
}
}
if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
LBO->getOperand(1) == RBO->getOperand(1)) {
switch (LBO->getOpcode()) {
default: break;
case Instruction::UDiv:
case Instruction::LShr:
if (ICmpInst::isSigned(Pred))
break;
// fall-through
case Instruction::SDiv:
case Instruction::AShr:
if (!LBO->isExact() || !RBO->isExact())
break;
if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
RBO->getOperand(0), Q, MaxRecurse-1))
return V;
break;
case Instruction::Shl: {
bool NUW = LBO->hasNoUnsignedWrap() && RBO->hasNoUnsignedWrap();
bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
if (!NUW && !NSW)
break;
if (!NSW && ICmpInst::isSigned(Pred))
break;
if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
RBO->getOperand(0), Q, MaxRecurse-1))
return V;
break;
}
}
}
// Simplify comparisons involving max/min.
Value *A, *B;
CmpInst::Predicate P = CmpInst::BAD_ICMP_PREDICATE;
CmpInst::Predicate EqP; // Chosen so that "A == max/min(A,B)" iff "A EqP B".
// Signed variants on "max(a,b)>=a -> true".
if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
if (A != RHS) std::swap(A, B); // smax(A, B) pred A.
EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
// We analyze this as smax(A, B) pred A.
P = Pred;
} else if (match(RHS, m_SMax(m_Value(A), m_Value(B))) &&
(A == LHS || B == LHS)) {
if (A != LHS) std::swap(A, B); // A pred smax(A, B).
EqP = CmpInst::ICMP_SGE; // "A == smax(A, B)" iff "A sge B".
// We analyze this as smax(A, B) swapped-pred A.
P = CmpInst::getSwappedPredicate(Pred);
} else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
(A == RHS || B == RHS)) {
if (A != RHS) std::swap(A, B); // smin(A, B) pred A.
EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
// We analyze this as smax(-A, -B) swapped-pred -A.
// Note that we do not need to actually form -A or -B thanks to EqP.
P = CmpInst::getSwappedPredicate(Pred);
} else if (match(RHS, m_SMin(m_Value(A), m_Value(B))) &&
(A == LHS || B == LHS)) {
if (A != LHS) std::swap(A, B); // A pred smin(A, B).
EqP = CmpInst::ICMP_SLE; // "A == smin(A, B)" iff "A sle B".
// We analyze this as smax(-A, -B) pred -A.
// Note that we do not need to actually form -A or -B thanks to EqP.
P = Pred;
}
if (P != CmpInst::BAD_ICMP_PREDICATE) {
// Cases correspond to "max(A, B) p A".
switch (P) {
default:
break;
case CmpInst::ICMP_EQ:
case CmpInst::ICMP_SLE:
// Equivalent to "A EqP B". This may be the same as the condition tested
// in the max/min; if so, we can just return that.
if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
return V;
if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
return V;
// Otherwise, see if "A EqP B" simplifies.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
return V;
break;
case CmpInst::ICMP_NE:
case CmpInst::ICMP_SGT: {
CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
// Equivalent to "A InvEqP B". This may be the same as the condition
// tested in the max/min; if so, we can just return that.
if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
return V;
if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
return V;
// Otherwise, see if "A InvEqP B" simplifies.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
return V;
break;
}
case CmpInst::ICMP_SGE:
// Always true.
return getTrue(ITy);
case CmpInst::ICMP_SLT:
// Always false.
return getFalse(ITy);
}
}
// Unsigned variants on "max(a,b)>=a -> true".
P = CmpInst::BAD_ICMP_PREDICATE;
if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && (A == RHS || B == RHS)) {
if (A != RHS) std::swap(A, B); // umax(A, B) pred A.
EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
// We analyze this as umax(A, B) pred A.
P = Pred;
} else if (match(RHS, m_UMax(m_Value(A), m_Value(B))) &&
(A == LHS || B == LHS)) {
if (A != LHS) std::swap(A, B); // A pred umax(A, B).
EqP = CmpInst::ICMP_UGE; // "A == umax(A, B)" iff "A uge B".
// We analyze this as umax(A, B) swapped-pred A.
P = CmpInst::getSwappedPredicate(Pred);
} else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
(A == RHS || B == RHS)) {
if (A != RHS) std::swap(A, B); // umin(A, B) pred A.
EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
// We analyze this as umax(-A, -B) swapped-pred -A.
// Note that we do not need to actually form -A or -B thanks to EqP.
P = CmpInst::getSwappedPredicate(Pred);
} else if (match(RHS, m_UMin(m_Value(A), m_Value(B))) &&
(A == LHS || B == LHS)) {
if (A != LHS) std::swap(A, B); // A pred umin(A, B).
EqP = CmpInst::ICMP_ULE; // "A == umin(A, B)" iff "A ule B".
// We analyze this as umax(-A, -B) pred -A.
// Note that we do not need to actually form -A or -B thanks to EqP.
P = Pred;
}
if (P != CmpInst::BAD_ICMP_PREDICATE) {
// Cases correspond to "max(A, B) p A".
switch (P) {
default:
break;
case CmpInst::ICMP_EQ:
case CmpInst::ICMP_ULE:
// Equivalent to "A EqP B". This may be the same as the condition tested
// in the max/min; if so, we can just return that.
if (Value *V = ExtractEquivalentCondition(LHS, EqP, A, B))
return V;
if (Value *V = ExtractEquivalentCondition(RHS, EqP, A, B))
return V;
// Otherwise, see if "A EqP B" simplifies.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(EqP, A, B, Q, MaxRecurse-1))
return V;
break;
case CmpInst::ICMP_NE:
case CmpInst::ICMP_UGT: {
CmpInst::Predicate InvEqP = CmpInst::getInversePredicate(EqP);
// Equivalent to "A InvEqP B". This may be the same as the condition
// tested in the max/min; if so, we can just return that.
if (Value *V = ExtractEquivalentCondition(LHS, InvEqP, A, B))
return V;
if (Value *V = ExtractEquivalentCondition(RHS, InvEqP, A, B))
return V;
// Otherwise, see if "A InvEqP B" simplifies.
if (MaxRecurse)
if (Value *V = SimplifyICmpInst(InvEqP, A, B, Q, MaxRecurse-1))
return V;
break;
}
case CmpInst::ICMP_UGE:
// Always true.
return getTrue(ITy);
case CmpInst::ICMP_ULT:
// Always false.
return getFalse(ITy);
}
}
// Variants on "max(x,y) >= min(x,z)".
Value *C, *D;
if (match(LHS, m_SMax(m_Value(A), m_Value(B))) &&
match(RHS, m_SMin(m_Value(C), m_Value(D))) &&
(A == C || A == D || B == C || B == D)) {
// max(x, ?) pred min(x, ?).
if (Pred == CmpInst::ICMP_SGE)
// Always true.
return getTrue(ITy);
if (Pred == CmpInst::ICMP_SLT)
// Always false.
return getFalse(ITy);
} else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) &&
match(RHS, m_SMax(m_Value(C), m_Value(D))) &&
(A == C || A == D || B == C || B == D)) {
// min(x, ?) pred max(x, ?).
if (Pred == CmpInst::ICMP_SLE)
// Always true.
return getTrue(ITy);
if (Pred == CmpInst::ICMP_SGT)
// Always false.
return getFalse(ITy);
} else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) &&
match(RHS, m_UMin(m_Value(C), m_Value(D))) &&
(A == C || A == D || B == C || B == D)) {
// max(x, ?) pred min(x, ?).
if (Pred == CmpInst::ICMP_UGE)
// Always true.
return getTrue(ITy);
if (Pred == CmpInst::ICMP_ULT)
// Always false.
return getFalse(ITy);
} else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) &&
match(RHS, m_UMax(m_Value(C), m_Value(D))) &&
(A == C || A == D || B == C || B == D)) {
// min(x, ?) pred max(x, ?).
if (Pred == CmpInst::ICMP_ULE)
// Always true.
return getTrue(ITy);
if (Pred == CmpInst::ICMP_UGT)
// Always false.
return getFalse(ITy);
}
// Simplify comparisons of related pointers using a powerful, recursive
// GEP-walk when we have target data available..
if (LHS->getType()->isPointerTy())
if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.CxtI, LHS, RHS))
return C;
if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) {
if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) {
if (GLHS->getPointerOperand() == GRHS->getPointerOperand() &&
GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() &&
(ICmpInst::isEquality(Pred) ||
(GLHS->isInBounds() && GRHS->isInBounds() &&
Pred == ICmpInst::getSignedPredicate(Pred)))) {
// The bases are equal and the indices are constant. Build a constant
// expression GEP with the same indices and a null base pointer to see
// what constant folding can make out of it.
Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType());
SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end());
Constant *NewLHS = ConstantExpr::getGetElementPtr(
GLHS->getSourceElementType(), Null, IndicesLHS);
SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end());
Constant *NewRHS = ConstantExpr::getGetElementPtr(
GLHS->getSourceElementType(), Null, IndicesRHS);
return ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
}
}
}
// If a bit is known to be zero for A and known to be one for B,
// then A and B cannot be equal.
if (ICmpInst::isEquality(Pred)) {
if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
uint32_t BitWidth = CI->getBitWidth();
APInt LHSKnownZero(BitWidth, 0);
APInt LHSKnownOne(BitWidth, 0);
computeKnownBits(LHS, LHSKnownZero, LHSKnownOne, Q.DL, /*Depth=*/0, Q.AC,
Q.CxtI, Q.DT);
const APInt &RHSVal = CI->getValue();
if (((LHSKnownZero & RHSVal) != 0) || ((LHSKnownOne & ~RHSVal) != 0))
return Pred == ICmpInst::ICMP_EQ
? ConstantInt::getFalse(CI->getContext())
: ConstantInt::getTrue(CI->getContext());
}
}
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
return V;
// If the comparison is with the result of a phi instruction, check whether
// doing the compare with each incoming phi value yields a common result.
if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
return V;
return nullptr;
}
Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyICmpInst(Predicate, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for an FCmpInst, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
FastMathFlags FMF, const Query &Q,
unsigned MaxRecurse) {
CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate;
assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!");
if (Constant *CLHS = dyn_cast<Constant>(LHS)) {
if (Constant *CRHS = dyn_cast<Constant>(RHS))
return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI);
// If we have a constant, make sure it is on the RHS.
std::swap(LHS, RHS);
Pred = CmpInst::getSwappedPredicate(Pred);
}
// Fold trivial predicates.
if (Pred == FCmpInst::FCMP_FALSE)
return ConstantInt::get(GetCompareTy(LHS), 0);
if (Pred == FCmpInst::FCMP_TRUE)
return ConstantInt::get(GetCompareTy(LHS), 1);
// UNO/ORD predicates can be trivially folded if NaNs are ignored.
if (FMF.noNaNs()) {
if (Pred == FCmpInst::FCMP_UNO)
return ConstantInt::get(GetCompareTy(LHS), 0);
if (Pred == FCmpInst::FCMP_ORD)
return ConstantInt::get(GetCompareTy(LHS), 1);
}
// fcmp pred x, undef and fcmp pred undef, x
// fold to true if unordered, false if ordered
if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS)) {
// Choosing NaN for the undef will always make unordered comparison succeed
// and ordered comparison fail.
return ConstantInt::get(GetCompareTy(LHS), CmpInst::isUnordered(Pred));
}
// fcmp x,x -> true/false. Not all compares are foldable.
if (LHS == RHS) {
if (CmpInst::isTrueWhenEqual(Pred))
return ConstantInt::get(GetCompareTy(LHS), 1);
if (CmpInst::isFalseWhenEqual(Pred))
return ConstantInt::get(GetCompareTy(LHS), 0);
}
// Handle fcmp with constant RHS
const ConstantFP *CFP = nullptr;
if (const auto *RHSC = dyn_cast<Constant>(RHS)) {
if (RHS->getType()->isVectorTy())
CFP = dyn_cast_or_null<ConstantFP>(RHSC->getSplatValue());
else
CFP = dyn_cast<ConstantFP>(RHSC);
}
if (CFP) {
// If the constant is a nan, see if we can fold the comparison based on it.
if (CFP->getValueAPF().isNaN()) {
if (FCmpInst::isOrdered(Pred)) // True "if ordered and foo"
return ConstantInt::getFalse(CFP->getContext());
assert(FCmpInst::isUnordered(Pred) &&
"Comparison must be either ordered or unordered!");
// True if unordered.
return ConstantInt::get(GetCompareTy(LHS), 1);
}
// Check whether the constant is an infinity.
if (CFP->getValueAPF().isInfinity()) {
if (CFP->getValueAPF().isNegative()) {
switch (Pred) {
case FCmpInst::FCMP_OLT:
// No value is ordered and less than negative infinity.
return ConstantInt::get(GetCompareTy(LHS), 0);
case FCmpInst::FCMP_UGE:
// All values are unordered with or at least negative infinity.
return ConstantInt::get(GetCompareTy(LHS), 1);
default:
break;
}
} else {
switch (Pred) {
case FCmpInst::FCMP_OGT:
// No value is ordered and greater than infinity.
return ConstantInt::get(GetCompareTy(LHS), 0);
case FCmpInst::FCMP_ULE:
// All values are unordered with and at most infinity.
return ConstantInt::get(GetCompareTy(LHS), 1);
default:
break;
}
}
}
if (CFP->getValueAPF().isZero()) {
switch (Pred) {
case FCmpInst::FCMP_UGE:
if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
return ConstantInt::get(GetCompareTy(LHS), 1);
break;
case FCmpInst::FCMP_OLT:
// X < 0
if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
return ConstantInt::get(GetCompareTy(LHS), 0);
break;
default:
break;
}
}
}
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse))
return V;
// If the comparison is with the result of a phi instruction, check whether
// doing the compare with each incoming phi value yields a common result.
if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse))
return V;
return nullptr;
}
Value *llvm::SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
FastMathFlags FMF, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyFCmpInst(Predicate, LHS, RHS, FMF,
Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
}
/// See if V simplifies when its operand Op is replaced with RepOp.
static const Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
const Query &Q,
unsigned MaxRecurse) {
// Trivial replacement.
if (V == Op)
return RepOp;
auto *I = dyn_cast<Instruction>(V);
if (!I)
return nullptr;
// If this is a binary operator, try to simplify it with the replaced op.
if (auto *B = dyn_cast<BinaryOperator>(I)) {
// Consider:
// %cmp = icmp eq i32 %x, 2147483647
// %add = add nsw i32 %x, 1
// %sel = select i1 %cmp, i32 -2147483648, i32 %add
//
// We can't replace %sel with %add unless we strip away the flags.
if (isa<OverflowingBinaryOperator>(B))
if (B->hasNoSignedWrap() || B->hasNoUnsignedWrap())
return nullptr;
if (isa<PossiblyExactOperator>(B))
if (B->isExact())
return nullptr;
if (MaxRecurse) {
if (B->getOperand(0) == Op)
return SimplifyBinOp(B->getOpcode(), RepOp, B->getOperand(1), Q,
MaxRecurse - 1);
if (B->getOperand(1) == Op)
return SimplifyBinOp(B->getOpcode(), B->getOperand(0), RepOp, Q,
MaxRecurse - 1);
}
}
// Same for CmpInsts.
if (CmpInst *C = dyn_cast<CmpInst>(I)) {
if (MaxRecurse) {
if (C->getOperand(0) == Op)
return SimplifyCmpInst(C->getPredicate(), RepOp, C->getOperand(1), Q,
MaxRecurse - 1);
if (C->getOperand(1) == Op)
return SimplifyCmpInst(C->getPredicate(), C->getOperand(0), RepOp, Q,
MaxRecurse - 1);
}
}
// TODO: We could hand off more cases to instsimplify here.
// If all operands are constant after substituting Op for RepOp then we can
// constant fold the instruction.
if (Constant *CRepOp = dyn_cast<Constant>(RepOp)) {
// Build a list of all constant operands.
SmallVector<Constant *, 8> ConstOps;
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
if (I->getOperand(i) == Op)
ConstOps.push_back(CRepOp);
else if (Constant *COp = dyn_cast<Constant>(I->getOperand(i)))
ConstOps.push_back(COp);
else
break;
}
// All operands were constants, fold it.
if (ConstOps.size() == I->getNumOperands()) {
if (CmpInst *C = dyn_cast<CmpInst>(I))
return ConstantFoldCompareInstOperands(C->getPredicate(), ConstOps[0],
ConstOps[1], Q.DL, Q.TLI);
if (LoadInst *LI = dyn_cast<LoadInst>(I))
if (!LI->isVolatile())
return ConstantFoldLoadFromConstPtr(ConstOps[0], LI->getType(), Q.DL);
return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI);
}
}
return nullptr;
}
/// Given operands for a SelectInst, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifySelectInst(Value *CondVal, Value *TrueVal,
Value *FalseVal, const Query &Q,
unsigned MaxRecurse) {
// select true, X, Y -> X
// select false, X, Y -> Y
if (Constant *CB = dyn_cast<Constant>(CondVal)) {
if (CB->isAllOnesValue())
return TrueVal;
if (CB->isNullValue())
return FalseVal;
}
// select C, X, X -> X
if (TrueVal == FalseVal)
return TrueVal;
if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
if (isa<Constant>(TrueVal))
return TrueVal;
return FalseVal;
}
if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
return FalseVal;
if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
return TrueVal;
if (const auto *ICI = dyn_cast<ICmpInst>(CondVal)) {
unsigned BitWidth = Q.DL.getTypeSizeInBits(TrueVal->getType());
ICmpInst::Predicate Pred = ICI->getPredicate();
Value *CmpLHS = ICI->getOperand(0);
Value *CmpRHS = ICI->getOperand(1);
APInt MinSignedValue = APInt::getSignBit(BitWidth);
Value *X;
const APInt *Y;
bool TrueWhenUnset;
bool IsBitTest = false;
if (ICmpInst::isEquality(Pred) &&
match(CmpLHS, m_And(m_Value(X), m_APInt(Y))) &&
match(CmpRHS, m_Zero())) {
IsBitTest = true;
TrueWhenUnset = Pred == ICmpInst::ICMP_EQ;
} else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) {
X = CmpLHS;
Y = &MinSignedValue;
IsBitTest = true;
TrueWhenUnset = false;
} else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) {
X = CmpLHS;
Y = &MinSignedValue;
IsBitTest = true;
TrueWhenUnset = true;
}
if (IsBitTest) {
const APInt *C;
// (X & Y) == 0 ? X & ~Y : X --> X
// (X & Y) != 0 ? X & ~Y : X --> X & ~Y
if (FalseVal == X && match(TrueVal, m_And(m_Specific(X), m_APInt(C))) &&
*Y == ~*C)
return TrueWhenUnset ? FalseVal : TrueVal;
// (X & Y) == 0 ? X : X & ~Y --> X & ~Y
// (X & Y) != 0 ? X : X & ~Y --> X
if (TrueVal == X && match(FalseVal, m_And(m_Specific(X), m_APInt(C))) &&
*Y == ~*C)
return TrueWhenUnset ? FalseVal : TrueVal;
if (Y->isPowerOf2()) {
// (X & Y) == 0 ? X | Y : X --> X | Y
// (X & Y) != 0 ? X | Y : X --> X
if (FalseVal == X && match(TrueVal, m_Or(m_Specific(X), m_APInt(C))) &&
*Y == *C)
return TrueWhenUnset ? TrueVal : FalseVal;
// (X & Y) == 0 ? X : X | Y --> X
// (X & Y) != 0 ? X : X | Y --> X | Y
if (TrueVal == X && match(FalseVal, m_Or(m_Specific(X), m_APInt(C))) &&
*Y == *C)
return TrueWhenUnset ? TrueVal : FalseVal;
}
}
if (ICI->hasOneUse()) {
const APInt *C;
if (match(CmpRHS, m_APInt(C))) {
// X < MIN ? T : F --> F
if (Pred == ICmpInst::ICMP_SLT && C->isMinSignedValue())
return FalseVal;
// X < MIN ? T : F --> F
if (Pred == ICmpInst::ICMP_ULT && C->isMinValue())
return FalseVal;
// X > MAX ? T : F --> F
if (Pred == ICmpInst::ICMP_SGT && C->isMaxSignedValue())
return FalseVal;
// X > MAX ? T : F --> F
if (Pred == ICmpInst::ICMP_UGT && C->isMaxValue())
return FalseVal;
}
}
// If we have an equality comparison then we know the value in one of the
// arms of the select. See if substituting this value into the arm and
// simplifying the result yields the same value as the other arm.
if (Pred == ICmpInst::ICMP_EQ) {
if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
TrueVal ||
SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
TrueVal)
return FalseVal;
if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
FalseVal ||
SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
FalseVal)
return FalseVal;
} else if (Pred == ICmpInst::ICMP_NE) {
if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
FalseVal ||
SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
FalseVal)
return TrueVal;
if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) ==
TrueVal ||
SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) ==
TrueVal)
return TrueVal;
}
}
return nullptr;
}
Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifySelectInst(Cond, TrueVal, FalseVal,
Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
}
/// Given operands for an GetElementPtrInst, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
const Query &Q, unsigned) {
// The type of the GEP pointer operand.
unsigned AS =
cast<PointerType>(Ops[0]->getType()->getScalarType())->getAddressSpace();
// getelementptr P -> P.
if (Ops.size() == 1)
return Ops[0];
// Compute the (pointer) type returned by the GEP instruction.
Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1));
Type *GEPTy = PointerType::get(LastType, AS);
if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType()))
GEPTy = VectorType::get(GEPTy, VT->getNumElements());
if (isa<UndefValue>(Ops[0]))
return UndefValue::get(GEPTy);
if (Ops.size() == 2) {
// getelementptr P, 0 -> P.
if (match(Ops[1], m_Zero()))
return Ops[0];
Type *Ty = SrcTy;
if (Ty->isSized()) {
Value *P;
uint64_t C;
uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty);
// getelementptr P, N -> P if P points to a type of zero size.
if (TyAllocSize == 0)
return Ops[0];
// The following transforms are only safe if the ptrtoint cast
// doesn't truncate the pointers.
if (Ops[1]->getType()->getScalarSizeInBits() ==
Q.DL.getPointerSizeInBits(AS)) {
auto PtrToIntOrZero = [GEPTy](Value *P) -> Value * {
if (match(P, m_Zero()))
return Constant::getNullValue(GEPTy);
Value *Temp;
if (match(P, m_PtrToInt(m_Value(Temp))))
if (Temp->getType() == GEPTy)
return Temp;
return nullptr;
};
// getelementptr V, (sub P, V) -> P if P points to a type of size 1.
if (TyAllocSize == 1 &&
match(Ops[1], m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0])))))
if (Value *R = PtrToIntOrZero(P))
return R;
// getelementptr V, (ashr (sub P, V), C) -> Q
// if P points to a type of size 1 << C.
if (match(Ops[1],
m_AShr(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
m_ConstantInt(C))) &&
TyAllocSize == 1ULL << C)
if (Value *R = PtrToIntOrZero(P))
return R;
// getelementptr V, (sdiv (sub P, V), C) -> Q
// if P points to a type of size C.
if (match(Ops[1],
m_SDiv(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))),
m_SpecificInt(TyAllocSize))))
if (Value *R = PtrToIntOrZero(P))
return R;
}
}
}
// Check to see if this is constant foldable.
for (unsigned i = 0, e = Ops.size(); i != e; ++i)
if (!isa<Constant>(Ops[i]))
return nullptr;
return ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ops[0]),
Ops.slice(1));
}
Value *llvm::SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyGEPInst(SrcTy, Ops,
Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
}
/// Given operands for an InsertValueInst, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyInsertValueInst(Value *Agg, Value *Val,
ArrayRef<unsigned> Idxs, const Query &Q,
unsigned) {
if (Constant *CAgg = dyn_cast<Constant>(Agg))
if (Constant *CVal = dyn_cast<Constant>(Val))
return ConstantFoldInsertValueInstruction(CAgg, CVal, Idxs);
// insertvalue x, undef, n -> x
if (match(Val, m_Undef()))
return Agg;
// insertvalue x, (extractvalue y, n), n
if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val))
if (EV->getAggregateOperand()->getType() == Agg->getType() &&
EV->getIndices() == Idxs) {
// insertvalue undef, (extractvalue y, n), n -> y
if (match(Agg, m_Undef()))
return EV->getAggregateOperand();
// insertvalue y, (extractvalue y, n), n -> y
if (Agg == EV->getAggregateOperand())
return Agg;
}
return nullptr;
}
Value *llvm::SimplifyInsertValueInst(
Value *Agg, Value *Val, ArrayRef<unsigned> Idxs, const DataLayout &DL,
const TargetLibraryInfo *TLI, const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyInsertValueInst(Agg, Val, Idxs, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for an ExtractValueInst, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs,
const Query &, unsigned) {
if (auto *CAgg = dyn_cast<Constant>(Agg))
return ConstantFoldExtractValueInstruction(CAgg, Idxs);
// extractvalue x, (insertvalue y, elt, n), n -> elt
unsigned NumIdxs = Idxs.size();
for (auto *IVI = dyn_cast<InsertValueInst>(Agg); IVI != nullptr;
IVI = dyn_cast<InsertValueInst>(IVI->getAggregateOperand())) {
ArrayRef<unsigned> InsertValueIdxs = IVI->getIndices();
unsigned NumInsertValueIdxs = InsertValueIdxs.size();
unsigned NumCommonIdxs = std::min(NumInsertValueIdxs, NumIdxs);
if (InsertValueIdxs.slice(0, NumCommonIdxs) ==
Idxs.slice(0, NumCommonIdxs)) {
if (NumIdxs == NumInsertValueIdxs)
return IVI->getInsertedValueOperand();
break;
}
}
return nullptr;
}
Value *llvm::SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT,
AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyExtractValueInst(Agg, Idxs, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for an ExtractElementInst, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyExtractElementInst(Value *Vec, Value *Idx, const Query &,
unsigned) {
if (auto *CVec = dyn_cast<Constant>(Vec)) {
if (auto *CIdx = dyn_cast<Constant>(Idx))
return ConstantFoldExtractElementInstruction(CVec, CIdx);
// The index is not relevant if our vector is a splat.
if (auto *Splat = CVec->getSplatValue())
return Splat;
if (isa<UndefValue>(Vec))
return UndefValue::get(Vec->getType()->getVectorElementType());
}
// If extracting a specified index from the vector, see if we can recursively
// find a previously computed scalar that was inserted into the vector.
if (auto *IdxC = dyn_cast<ConstantInt>(Idx))
if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue()))
return Elt;
return nullptr;
}
Value *llvm::SimplifyExtractElementInst(
Value *Vec, Value *Idx, const DataLayout &DL, const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC, const Instruction *CxtI) {
return ::SimplifyExtractElementInst(Vec, Idx, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// See if we can fold the given phi. If not, returns null.
static Value *SimplifyPHINode(PHINode *PN, const Query &Q) {
// If all of the PHI's incoming values are the same then replace the PHI node
// with the common value.
Value *CommonValue = nullptr;
bool HasUndefInput = false;
for (Value *Incoming : PN->incoming_values()) {
// If the incoming value is the phi node itself, it can safely be skipped.
if (Incoming == PN) continue;
if (isa<UndefValue>(Incoming)) {
// Remember that we saw an undef value, but otherwise ignore them.
HasUndefInput = true;
continue;
}
if (CommonValue && Incoming != CommonValue)
return nullptr; // Not the same, bail out.
CommonValue = Incoming;
}
// If CommonValue is null then all of the incoming values were either undef or
// equal to the phi node itself.
if (!CommonValue)
return UndefValue::get(PN->getType());
// If we have a PHI node like phi(X, undef, X), where X is defined by some
// instruction, we cannot return X as the result of the PHI node unless it
// dominates the PHI block.
if (HasUndefInput)
return ValueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr;
return CommonValue;
}
static Value *SimplifyTruncInst(Value *Op, Type *Ty, const Query &Q, unsigned) {
if (Constant *C = dyn_cast<Constant>(Op))
return ConstantFoldCastOperand(Instruction::Trunc, C, Ty, Q.DL);
return nullptr;
}
Value *llvm::SimplifyTruncInst(Value *Op, Type *Ty, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyTruncInst(Op, Ty, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
//=== Helper functions for higher up the class hierarchy.
/// Given operands for a BinaryOperator, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const Query &Q, unsigned MaxRecurse) {
switch (Opcode) {
case Instruction::Add:
return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
Q, MaxRecurse);
case Instruction::FAdd:
return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
case Instruction::Sub:
return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
Q, MaxRecurse);
case Instruction::FSub:
return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
case Instruction::Mul: return SimplifyMulInst (LHS, RHS, Q, MaxRecurse);
case Instruction::FMul:
return SimplifyFMulInst (LHS, RHS, FastMathFlags(), Q, MaxRecurse);
case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
case Instruction::FDiv:
return SimplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
case Instruction::SRem: return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
case Instruction::URem: return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
case Instruction::FRem:
return SimplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
case Instruction::Shl:
return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
Q, MaxRecurse);
case Instruction::LShr:
return SimplifyLShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
case Instruction::AShr:
return SimplifyAShrInst(LHS, RHS, /*isExact*/false, Q, MaxRecurse);
case Instruction::And: return SimplifyAndInst(LHS, RHS, Q, MaxRecurse);
case Instruction::Or: return SimplifyOrInst (LHS, RHS, Q, MaxRecurse);
case Instruction::Xor: return SimplifyXorInst(LHS, RHS, Q, MaxRecurse);
default:
if (Constant *CLHS = dyn_cast<Constant>(LHS))
if (Constant *CRHS = dyn_cast<Constant>(RHS))
return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL);
// If the operation is associative, try some generic simplifications.
if (Instruction::isAssociative(Opcode))
if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, Q, MaxRecurse))
return V;
// If the operation is with the result of a select instruction check whether
// operating on either branch of the select always yields the same value.
if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, Q, MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, Q, MaxRecurse))
return V;
return nullptr;
}
}
/// Given operands for a BinaryOperator, see if we can fold the result.
/// If not, this returns null.
/// In contrast to SimplifyBinOp, try to use FastMathFlag when folding the
/// result. In case we don't need FastMathFlags, simply fall to SimplifyBinOp.
static Value *SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const FastMathFlags &FMF, const Query &Q,
unsigned MaxRecurse) {
switch (Opcode) {
case Instruction::FAdd:
return SimplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse);
case Instruction::FSub:
return SimplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse);
case Instruction::FMul:
return SimplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse);
default:
return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse);
}
}
Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const DataLayout &DL, const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyBinOp(Opcode, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
Value *llvm::SimplifyFPBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const FastMathFlags &FMF, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyFPBinOp(Opcode, LHS, RHS, FMF, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
/// Given operands for a CmpInst, see if we can fold the result.
static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const Query &Q, unsigned MaxRecurse) {
if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate))
return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse);
return SimplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse);
}
Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const DataLayout &DL, const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyCmpInst(Predicate, LHS, RHS, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
static bool IsIdempotent(Intrinsic::ID ID) {
switch (ID) {
default: return false;
// Unary idempotent: f(f(x)) = f(x)
case Intrinsic::fabs:
case Intrinsic::floor:
case Intrinsic::ceil:
case Intrinsic::trunc:
case Intrinsic::rint:
case Intrinsic::nearbyint:
case Intrinsic::round:
return true;
}
}
static Value *SimplifyRelativeLoad(Constant *Ptr, Constant *Offset,
const DataLayout &DL) {
GlobalValue *PtrSym;
APInt PtrOffset;
if (!IsConstantOffsetFromGlobal(Ptr, PtrSym, PtrOffset, DL))
return nullptr;
Type *Int8PtrTy = Type::getInt8PtrTy(Ptr->getContext());
Type *Int32Ty = Type::getInt32Ty(Ptr->getContext());
Type *Int32PtrTy = Int32Ty->getPointerTo();
Type *Int64Ty = Type::getInt64Ty(Ptr->getContext());
auto *OffsetConstInt = dyn_cast<ConstantInt>(Offset);
if (!OffsetConstInt || OffsetConstInt->getType()->getBitWidth() > 64)
return nullptr;
uint64_t OffsetInt = OffsetConstInt->getSExtValue();
if (OffsetInt % 4 != 0)
return nullptr;
Constant *C = ConstantExpr::getGetElementPtr(
Int32Ty, ConstantExpr::getBitCast(Ptr, Int32PtrTy),
ConstantInt::get(Int64Ty, OffsetInt / 4));
Constant *Loaded = ConstantFoldLoadFromConstPtr(C, Int32Ty, DL);
if (!Loaded)
return nullptr;
auto *LoadedCE = dyn_cast<ConstantExpr>(Loaded);
if (!LoadedCE)
return nullptr;
if (LoadedCE->getOpcode() == Instruction::Trunc) {
LoadedCE = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
if (!LoadedCE)
return nullptr;
}
if (LoadedCE->getOpcode() != Instruction::Sub)
return nullptr;
auto *LoadedLHS = dyn_cast<ConstantExpr>(LoadedCE->getOperand(0));
if (!LoadedLHS || LoadedLHS->getOpcode() != Instruction::PtrToInt)
return nullptr;
auto *LoadedLHSPtr = LoadedLHS->getOperand(0);
Constant *LoadedRHS = LoadedCE->getOperand(1);
GlobalValue *LoadedRHSSym;
APInt LoadedRHSOffset;
if (!IsConstantOffsetFromGlobal(LoadedRHS, LoadedRHSSym, LoadedRHSOffset,
DL) ||
PtrSym != LoadedRHSSym || PtrOffset != LoadedRHSOffset)
return nullptr;
return ConstantExpr::getBitCast(LoadedLHSPtr, Int8PtrTy);
}
template <typename IterTy>
static Value *SimplifyIntrinsic(Function *F, IterTy ArgBegin, IterTy ArgEnd,
const Query &Q, unsigned MaxRecurse) {
Intrinsic::ID IID = F->getIntrinsicID();
unsigned NumOperands = std::distance(ArgBegin, ArgEnd);
Type *ReturnType = F->getReturnType();
// Binary Ops
if (NumOperands == 2) {
Value *LHS = *ArgBegin;
Value *RHS = *(ArgBegin + 1);
if (IID == Intrinsic::usub_with_overflow ||
IID == Intrinsic::ssub_with_overflow) {
// X - X -> { 0, false }
if (LHS == RHS)
return Constant::getNullValue(ReturnType);
// X - undef -> undef
// undef - X -> undef
if (isa<UndefValue>(LHS) || isa<UndefValue>(RHS))
return UndefValue::get(ReturnType);
}
if (IID == Intrinsic::uadd_with_overflow ||
IID == Intrinsic::sadd_with_overflow) {
// X + undef -> undef
if (isa<UndefValue>(RHS))
return UndefValue::get(ReturnType);
}
if (IID == Intrinsic::umul_with_overflow ||
IID == Intrinsic::smul_with_overflow) {
// X * 0 -> { 0, false }
if (match(RHS, m_Zero()))
return Constant::getNullValue(ReturnType);
// X * undef -> { 0, false }
if (match(RHS, m_Undef()))
return Constant::getNullValue(ReturnType);
}
if (IID == Intrinsic::load_relative && isa<Constant>(LHS) &&
isa<Constant>(RHS))
return SimplifyRelativeLoad(cast<Constant>(LHS), cast<Constant>(RHS),
Q.DL);
}
// Perform idempotent optimizations
if (!IsIdempotent(IID))
return nullptr;
// Unary Ops
if (NumOperands == 1)
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin))
if (II->getIntrinsicID() == IID)
return II;
return nullptr;
}
template <typename IterTy>
static Value *SimplifyCall(Value *V, IterTy ArgBegin, IterTy ArgEnd,
const Query &Q, unsigned MaxRecurse) {
Type *Ty = V->getType();
if (PointerType *PTy = dyn_cast<PointerType>(Ty))
Ty = PTy->getElementType();
FunctionType *FTy = cast<FunctionType>(Ty);
// call undef -> undef
if (isa<UndefValue>(V))
return UndefValue::get(FTy->getReturnType());
Function *F = dyn_cast<Function>(V);
if (!F)
return nullptr;
if (F->isIntrinsic())
if (Value *Ret = SimplifyIntrinsic(F, ArgBegin, ArgEnd, Q, MaxRecurse))
return Ret;
if (!canConstantFoldCallTo(F))
return nullptr;
SmallVector<Constant *, 4> ConstantArgs;
ConstantArgs.reserve(ArgEnd - ArgBegin);
for (IterTy I = ArgBegin, E = ArgEnd; I != E; ++I) {
Constant *C = dyn_cast<Constant>(*I);
if (!C)
return nullptr;
ConstantArgs.push_back(C);
}
return ConstantFoldCall(F, ConstantArgs, Q.TLI);
}
Value *llvm::SimplifyCall(Value *V, User::op_iterator ArgBegin,
User::op_iterator ArgEnd, const DataLayout &DL,
const TargetLibraryInfo *TLI, const DominatorTree *DT,
AssumptionCache *AC, const Instruction *CxtI) {
return ::SimplifyCall(V, ArgBegin, ArgEnd, Query(DL, TLI, DT, AC, CxtI),
RecursionLimit);
}
Value *llvm::SimplifyCall(Value *V, ArrayRef<Value *> Args,
const DataLayout &DL, const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
const Instruction *CxtI) {
return ::SimplifyCall(V, Args.begin(), Args.end(),
Query(DL, TLI, DT, AC, CxtI), RecursionLimit);
}
/// See if we can compute a simplified version of this instruction.
/// If not, this returns null.
Value *llvm::SimplifyInstruction(Instruction *I, const DataLayout &DL,
const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC) {
Value *Result;
switch (I->getOpcode()) {
default:
Result = ConstantFoldInstruction(I, DL, TLI);
break;
case Instruction::FAdd:
Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), DL, TLI, DT, AC, I);
break;
case Instruction::Add:
Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(), DL,
TLI, DT, AC, I);
break;
case Instruction::FSub:
Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), DL, TLI, DT, AC, I);
break;
case Instruction::Sub:
Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(), DL,
TLI, DT, AC, I);
break;
case Instruction::FMul:
Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), DL, TLI, DT, AC, I);
break;
case Instruction::Mul:
Result =
SimplifyMulInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
break;
case Instruction::SDiv:
Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
AC, I);
break;
case Instruction::UDiv:
Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
AC, I);
break;
case Instruction::FDiv:
Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), DL, TLI, DT, AC, I);
break;
case Instruction::SRem:
Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
AC, I);
break;
case Instruction::URem:
Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT,
AC, I);
break;
case Instruction::FRem:
Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), DL, TLI, DT, AC, I);
break;
case Instruction::Shl:
Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(), DL,
TLI, DT, AC, I);
break;
case Instruction::LShr:
Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->isExact(), DL, TLI, DT,
AC, I);
break;
case Instruction::AShr:
Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->isExact(), DL, TLI, DT,
AC, I);
break;
case Instruction::And:
Result =
SimplifyAndInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
break;
case Instruction::Or:
Result =
SimplifyOrInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
break;
case Instruction::Xor:
Result =
SimplifyXorInst(I->getOperand(0), I->getOperand(1), DL, TLI, DT, AC, I);
break;
case Instruction::ICmp:
Result =
SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), I->getOperand(0),
I->getOperand(1), DL, TLI, DT, AC, I);
break;
case Instruction::FCmp:
Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), DL, TLI, DT, AC, I);
break;
case Instruction::Select:
Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
I->getOperand(2), DL, TLI, DT, AC, I);
break;
case Instruction::GetElementPtr: {
SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
Result = SimplifyGEPInst(cast<GetElementPtrInst>(I)->getSourceElementType(),
Ops, DL, TLI, DT, AC, I);
break;
}
case Instruction::InsertValue: {
InsertValueInst *IV = cast<InsertValueInst>(I);
Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
IV->getInsertedValueOperand(),
IV->getIndices(), DL, TLI, DT, AC, I);
break;
}
case Instruction::ExtractValue: {
auto *EVI = cast<ExtractValueInst>(I);
Result = SimplifyExtractValueInst(EVI->getAggregateOperand(),
EVI->getIndices(), DL, TLI, DT, AC, I);
break;
}
case Instruction::ExtractElement: {
auto *EEI = cast<ExtractElementInst>(I);
Result = SimplifyExtractElementInst(
EEI->getVectorOperand(), EEI->getIndexOperand(), DL, TLI, DT, AC, I);
break;
}
case Instruction::PHI:
Result = SimplifyPHINode(cast<PHINode>(I), Query(DL, TLI, DT, AC, I));
break;
case Instruction::Call: {
CallSite CS(cast<CallInst>(I));
Result = SimplifyCall(CS.getCalledValue(), CS.arg_begin(), CS.arg_end(), DL,
TLI, DT, AC, I);
break;
}
case Instruction::Trunc:
Result =
SimplifyTruncInst(I->getOperand(0), I->getType(), DL, TLI, DT, AC, I);
break;
}
// In general, it is possible for computeKnownBits to determine all bits in a
// value even when the operands are not all constants.
if (!Result && I->getType()->isIntegerTy()) {
unsigned BitWidth = I->getType()->getScalarSizeInBits();
APInt KnownZero(BitWidth, 0);
APInt KnownOne(BitWidth, 0);
computeKnownBits(I, KnownZero, KnownOne, DL, /*Depth*/0, AC, I, DT);
if ((KnownZero | KnownOne).isAllOnesValue())
Result = ConstantInt::get(I->getContext(), KnownOne);
}
/// If called on unreachable code, the above logic may report that the
/// instruction simplified to itself. Make life easier for users by
/// detecting that case here, returning a safe value instead.
return Result == I ? UndefValue::get(I->getType()) : Result;
}
/// \brief Implementation of recursive simplification through an instruction's
/// uses.
///
/// This is the common implementation of the recursive simplification routines.
/// If we have a pre-simplified value in 'SimpleV', that is forcibly used to
/// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of
/// instructions to process and attempt to simplify it using
/// InstructionSimplify.
///
/// This routine returns 'true' only when *it* simplifies something. The passed
/// in simplified value does not count toward this.
static bool replaceAndRecursivelySimplifyImpl(Instruction *I, Value *SimpleV,
const TargetLibraryInfo *TLI,
const DominatorTree *DT,
AssumptionCache *AC) {
bool Simplified = false;
SmallSetVector<Instruction *, 8> Worklist;
const DataLayout &DL = I->getModule()->getDataLayout();
// If we have an explicit value to collapse to, do that round of the
// simplification loop by hand initially.
if (SimpleV) {
for (User *U : I->users())
if (U != I)
Worklist.insert(cast<Instruction>(U));
// Replace the instruction with its simplified value.
I->replaceAllUsesWith(SimpleV);
// Gracefully handle edge cases where the instruction is not wired into any
// parent block.
if (I->getParent())
I->eraseFromParent();
} else {
Worklist.insert(I);
}
// Note that we must test the size on each iteration, the worklist can grow.
for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
I = Worklist[Idx];
// See if this instruction simplifies.
SimpleV = SimplifyInstruction(I, DL, TLI, DT, AC);
if (!SimpleV)
continue;
Simplified = true;
// Stash away all the uses of the old instruction so we can check them for
// recursive simplifications after a RAUW. This is cheaper than checking all
// uses of To on the recursive step in most cases.
for (User *U : I->users())
Worklist.insert(cast<Instruction>(U));
// Replace the instruction with its simplified value.
I->replaceAllUsesWith(SimpleV);
// Gracefully handle edge cases where the instruction is not wired into any
// parent block.
if (I->getParent())
I->eraseFromParent();
}
return Simplified;
}
bool llvm::recursivelySimplifyInstruction(Instruction *I,
const TargetLibraryInfo *TLI,
const DominatorTree *DT,
AssumptionCache *AC) {
return replaceAndRecursivelySimplifyImpl(I, nullptr, TLI, DT, AC);
}
bool llvm::replaceAndRecursivelySimplify(Instruction *I, Value *SimpleV,
const TargetLibraryInfo *TLI,
const DominatorTree *DT,
AssumptionCache *AC) {
assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
assert(SimpleV && "Must provide a simplified value.");
return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC);
}
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