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llvm-mirror/lib/Analysis/InstructionSimplify.cpp
Nikita Popov befc0b53a8 [InstSimplify] Clean up SimplifyReplacedWithOp implementation (NFCI) 
Replace Op with RepOp up-front, and then always work with the new
operands, rather than checking for replacement in various places.
2021-03-21 15:30:30 +01:00

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//===- InstructionSimplify.cpp - Fold instruction operands ----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// 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/AssumptionCache.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/CmpInstAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/LoopAnalysisManager.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/InstrTypes.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/KnownBits.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");
static Value *SimplifyAndInst(Value *, Value *, const SimplifyQuery &, unsigned);
static Value *simplifyUnOp(unsigned, Value *, const SimplifyQuery &, unsigned);
static Value *simplifyFPUnOp(unsigned, Value *, const FastMathFlags &,
const SimplifyQuery &, unsigned);
static Value *SimplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &,
unsigned);
static Value *SimplifyBinOp(unsigned, Value *, Value *, const FastMathFlags &,
const SimplifyQuery &, unsigned);
static Value *SimplifyCmpInst(unsigned, Value *, Value *, const SimplifyQuery &,
unsigned);
static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const SimplifyQuery &Q, unsigned MaxRecurse);
static Value *SimplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned);
static Value *SimplifyXorInst(Value *, Value *, const SimplifyQuery &, unsigned);
static Value *SimplifyCastInst(unsigned, Value *, Type *,
const SimplifyQuery &, unsigned);
static Value *SimplifyGEPInst(Type *, ArrayRef<Value *>, const SimplifyQuery &,
unsigned);
static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal,
Value *FalseVal) {
BinaryOperator::BinaryOps BinOpCode;
if (auto *BO = dyn_cast<BinaryOperator>(Cond))
BinOpCode = BO->getOpcode();
else
return nullptr;
CmpInst::Predicate ExpectedPred, Pred1, Pred2;
if (BinOpCode == BinaryOperator::Or) {
ExpectedPred = ICmpInst::ICMP_NE;
} else if (BinOpCode == BinaryOperator::And) {
ExpectedPred = ICmpInst::ICMP_EQ;
} else
return nullptr;
// %A = icmp eq %TV, %FV
// %B = icmp eq %X, %Y (and one of these is a select operand)
// %C = and %A, %B
// %D = select %C, %TV, %FV
// -->
// %FV
// %A = icmp ne %TV, %FV
// %B = icmp ne %X, %Y (and one of these is a select operand)
// %C = or %A, %B
// %D = select %C, %TV, %FV
// -->
// %TV
Value *X, *Y;
if (!match(Cond, m_c_BinOp(m_c_ICmp(Pred1, m_Specific(TrueVal),
m_Specific(FalseVal)),
m_ICmp(Pred2, m_Value(X), m_Value(Y)))) ||
Pred1 != Pred2 || Pred1 != ExpectedPred)
return nullptr;
if (X == TrueVal || X == FalseVal || Y == TrueVal || Y == FalseVal)
return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal;
return nullptr;
}
/// For a boolean type or a vector of boolean type, return false or a vector
/// with every element false.
static Constant *getFalse(Type *Ty) {
return ConstantInt::getFalse(Ty);
}
/// For a boolean type or a vector of boolean type, return true or a vector
/// with every element true.
static Constant *getTrue(Type *Ty) {
return ConstantInt::getTrue(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;
}
/// Simplify comparison with true or false branch of select:
/// %sel = select i1 %cond, i32 %tv, i32 %fv
/// %cmp = icmp sle i32 %sel, %rhs
/// Compose new comparison by substituting %sel with either %tv or %fv
/// and see if it simplifies.
static Value *simplifyCmpSelCase(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, Value *Cond,
const SimplifyQuery &Q, unsigned MaxRecurse,
Constant *TrueOrFalse) {
Value *SimplifiedCmp = SimplifyCmpInst(Pred, LHS, RHS, Q, MaxRecurse);
if (SimplifiedCmp == Cond) {
// %cmp simplified to the select condition (%cond).
return TrueOrFalse;
} else if (!SimplifiedCmp && isSameCompare(Cond, Pred, LHS, RHS)) {
// It didn't simplify. However, if composed comparison is equivalent
// to the select condition (%cond) then we can replace it.
return TrueOrFalse;
}
return SimplifiedCmp;
}
/// Simplify comparison with true branch of select
static Value *simplifyCmpSelTrueCase(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, Value *Cond,
const SimplifyQuery &Q,
unsigned MaxRecurse) {
return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse,
getTrue(Cond->getType()));
}
/// Simplify comparison with false branch of select
static Value *simplifyCmpSelFalseCase(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, Value *Cond,
const SimplifyQuery &Q,
unsigned MaxRecurse) {
return simplifyCmpSelCase(Pred, LHS, RHS, Cond, Q, MaxRecurse,
getFalse(Cond->getType()));
}
/// We know comparison with both branches of select can be simplified, but they
/// are not equal. This routine handles some logical simplifications.
static Value *handleOtherCmpSelSimplifications(Value *TCmp, Value *FCmp,
Value *Cond,
const SimplifyQuery &Q,
unsigned MaxRecurse) {
// 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;
}
/// 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->getFunction())
return false;
// If we have a DominatorTree then do a precise test.
if (DT)
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->getFunction()->getEntryBlock() &&
!isa<InvokeInst>(I) && !isa<CallBrInst>(I))
return true;
return false;
}
/// Try to simplify a binary operator of form "V op OtherOp" where V is
/// "(B0 opex B1)" by distributing 'op' across 'opex' as
/// "(B0 op OtherOp) opex (B1 op OtherOp)".
static Value *expandBinOp(Instruction::BinaryOps Opcode, Value *V,
Value *OtherOp, Instruction::BinaryOps OpcodeToExpand,
const SimplifyQuery &Q, unsigned MaxRecurse) {
auto *B = dyn_cast<BinaryOperator>(V);
if (!B || B->getOpcode() != OpcodeToExpand)
return nullptr;
Value *B0 = B->getOperand(0), *B1 = B->getOperand(1);
Value *L = SimplifyBinOp(Opcode, B0, OtherOp, Q.getWithoutUndef(),
MaxRecurse);
if (!L)
return nullptr;
Value *R = SimplifyBinOp(Opcode, B1, OtherOp, Q.getWithoutUndef(),
MaxRecurse);
if (!R)
return nullptr;
// Does the expanded pair of binops simplify to the existing binop?
if ((L == B0 && R == B1) ||
(Instruction::isCommutative(OpcodeToExpand) && L == B1 && R == B0)) {
++NumExpand;
return B;
}
// Otherwise, return "L op' R" if it simplifies.
Value *S = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse);
if (!S)
return nullptr;
++NumExpand;
return S;
}
/// Try to simplify binops of form "A op (B op' C)" or the commuted variant by
/// distributing op over op'.
static Value *expandCommutativeBinOp(Instruction::BinaryOps Opcode,
Value *L, Value *R,
Instruction::BinaryOps OpcodeToExpand,
const SimplifyQuery &Q,
unsigned MaxRecurse) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return nullptr;
if (Value *V = expandBinOp(Opcode, L, R, OpcodeToExpand, Q, MaxRecurse))
return V;
if (Value *V = expandBinOp(Opcode, R, L, OpcodeToExpand, Q, MaxRecurse))
return V;
return nullptr;
}
/// Generic simplifications for associative binary operations.
/// Returns the simpler value, or null if none was found.
static Value *SimplifyAssociativeBinOp(Instruction::BinaryOps Opcode,
Value *LHS, Value *RHS,
const SimplifyQuery &Q,
unsigned MaxRecurse) {
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(Instruction::BinaryOps Opcode, Value *LHS,
Value *RHS, const SimplifyQuery &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 && Q.isUndefValue(TV))
return FV;
if (FV && Q.isUndefValue(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() == unsigned(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.
/// For example, if we have:
/// %tmp = select i1 %cmp, i32 1, i32 2
/// %cmp1 = icmp sle i32 %tmp, 3
/// We can simplify %cmp1 to true, because both branches of select are
/// less than 3. We compose new comparison by substituting %tmp with both
/// branches of select and see if it can be simplified.
static Value *ThreadCmpOverSelect(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const SimplifyQuery &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 = simplifyCmpSelTrueCase(Pred, TV, RHS, Cond, Q, MaxRecurse);
if (!TCmp)
return nullptr;
// Does "cmp FV, RHS" simplify?
Value *FCmp = simplifyCmpSelFalseCase(Pred, FV, RHS, Cond, Q, MaxRecurse);
if (!FCmp)
return nullptr;
// 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 handleOtherCmpSelSimplifications(TCmp, FCmp, Cond, Q, MaxRecurse);
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(Instruction::BinaryOps Opcode, Value *LHS,
Value *RHS, const SimplifyQuery &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 SimplifyQuery &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 (unsigned u = 0, e = PI->getNumIncomingValues(); u < e; ++u) {
Value *Incoming = PI->getIncomingValue(u);
Instruction *InTI = PI->getIncomingBlock(u)->getTerminator();
// If the incoming value is the phi node itself, it can safely be skipped.
if (Incoming == PI) continue;
// Change the context instruction to the "edge" that flows into the phi.
// This is important because that is where incoming is actually "evaluated"
// even though it is used later somewhere else.
Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q.getWithInstruction(InTI),
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;
}
static Constant *foldOrCommuteConstant(Instruction::BinaryOps Opcode,
Value *&Op0, Value *&Op1,
const SimplifyQuery &Q) {
if (auto *CLHS = dyn_cast<Constant>(Op0)) {
if (auto *CRHS = dyn_cast<Constant>(Op1))
return ConstantFoldBinaryOpOperands(Opcode, CLHS, CRHS, Q.DL);
// Canonicalize the constant to the RHS if this is a commutative operation.
if (Instruction::isCommutative(Opcode))
std::swap(Op0, Op1);
}
return nullptr;
}
/// 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 SimplifyQuery &Q, unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Instruction::Add, Op0, Op1, Q))
return C;
// X + undef -> undef
if (Q.isUndefValue(Op1))
return Op1;
// X + 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// If two operands are negative, return 0.
if (isKnownNegation(Op0, Op1))
return Constant::getNullValue(Op0->getType());
// 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
Type *Ty = Op0->getType();
if (match(Op0, m_Not(m_Specific(Op1))) ||
match(Op1, m_Not(m_Specific(Op0))))
return Constant::getAllOnesValue(Ty);
// add nsw/nuw (xor Y, signmask), signmask --> Y
// The no-wrapping add guarantees that the top bit will be set by the add.
// Therefore, the xor must be clearing the already set sign bit of Y.
if ((IsNSW || IsNUW) && match(Op1, m_SignMask()) &&
match(Op0, m_Xor(m_Value(Y), m_SignMask())))
return Y;
// add nuw %x, -1 -> -1, because %x can only be 0.
if (IsNUW && match(Op1, m_AllOnes()))
return Op1; // Which is -1.
/// i1 add -> xor.
if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(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 SimplifyQuery &Query) {
return ::SimplifyAddInst(Op0, Op1, IsNSW, IsNUW, Query, RecursionLimit);
}
/// 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()->isPtrOrPtrVectorTy());
Type *IntIdxTy = DL.getIndexType(V->getType())->getScalarType();
APInt Offset = APInt::getNullValue(IntIdxTy->getIntegerBitWidth());
V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds);
// As that strip may trace through `addrspacecast`, need to sext or trunc
// the offset calculated.
IntIdxTy = DL.getIndexType(V->getType())->getScalarType();
Offset = Offset.sextOrTrunc(IntIdxTy->getIntegerBitWidth());
Constant *OffsetIntPtr = ConstantInt::get(IntIdxTy, Offset);
if (VectorType *VecTy = dyn_cast<VectorType>(V->getType()))
return ConstantVector::getSplat(VecTy->getElementCount(), OffsetIntPtr);
return OffsetIntPtr;
}
/// 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 SimplifyQuery &Q, unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q))
return C;
// X - undef -> undef
// undef - X -> undef
if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1))
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());
// Is this a negation?
if (match(Op0, m_Zero())) {
// 0 - X -> 0 if the sub is NUW.
if (isNUW)
return Constant::getNullValue(Op0->getType());
KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (Known.Zero.isMaxSignedValue()) {
// Op1 is either 0 or the minimum signed value. If the sub is NSW, then
// Op1 must be 0 because negating the minimum signed value is undefined.
if (isNSW)
return Constant::getNullValue(Op0->getType());
// 0 - X -> X if X is 0 or the minimum signed value.
return Op1;
}
}
// (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 = SimplifyCastInst(Instruction::Trunc, 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()->isIntOrIntVectorTy(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 SimplifyQuery &Q) {
return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit);
}
/// 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 SimplifyQuery &Q,
unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q))
return C;
// X * undef -> 0
// X * 0 -> 0
if (Q.isUndefValue(Op1) || match(Op1, m_Zero()))
return Constant::getNullValue(Op0->getType());
// X * 1 -> X
if (match(Op1, m_One()))
return Op0;
// (X / Y) * Y -> X if the division is exact.
Value *X = nullptr;
if (Q.IIQ.UseInstrInfo &&
(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()->isIntOrIntVectorTy(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 = expandCommutativeBinOp(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::SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
return ::SimplifyMulInst(Op0, Op1, Q, RecursionLimit);
}
/// Check for common or similar folds of integer division or integer remainder.
/// This applies to all 4 opcodes (sdiv/udiv/srem/urem).
static Value *simplifyDivRem(Value *Op0, Value *Op1, bool IsDiv,
const SimplifyQuery &Q) {
Type *Ty = Op0->getType();
// X / undef -> poison
// X % undef -> poison
if (Q.isUndefValue(Op1))
return PoisonValue::get(Ty);
// X / 0 -> poison
// X % 0 -> poison
// We don't need to preserve faults!
if (match(Op1, m_Zero()))
return PoisonValue::get(Ty);
// If any element of a constant divisor fixed width vector is zero or undef
// the behavior is undefined and we can fold the whole op to poison.
auto *Op1C = dyn_cast<Constant>(Op1);
auto *VTy = dyn_cast<FixedVectorType>(Ty);
if (Op1C && VTy) {
unsigned NumElts = VTy->getNumElements();
for (unsigned i = 0; i != NumElts; ++i) {
Constant *Elt = Op1C->getAggregateElement(i);
if (Elt && (Elt->isNullValue() || Q.isUndefValue(Elt)))
return PoisonValue::get(Ty);
}
}
// undef / X -> 0
// undef % X -> 0
if (Q.isUndefValue(Op0))
return Constant::getNullValue(Ty);
// 0 / X -> 0
// 0 % X -> 0
if (match(Op0, m_Zero()))
return Constant::getNullValue(Op0->getType());
// X / X -> 1
// X % X -> 0
if (Op0 == Op1)
return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty);
// X / 1 -> X
// X % 1 -> 0
// If this is a boolean op (single-bit element type), we can't have
// division-by-zero or remainder-by-zero, so assume the divisor is 1.
// Similarly, if we're zero-extending a boolean divisor, then assume it's a 1.
Value *X;
if (match(Op1, m_One()) || Ty->isIntOrIntVectorTy(1) ||
(match(Op1, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)))
return IsDiv ? Op0 : Constant::getNullValue(Ty);
return nullptr;
}
/// Given a predicate and two operands, return true if the comparison is true.
/// This is a helper for div/rem simplification where we return some other value
/// when we can prove a relationship between the operands.
static bool isICmpTrue(ICmpInst::Predicate Pred, Value *LHS, Value *RHS,
const SimplifyQuery &Q, unsigned MaxRecurse) {
Value *V = SimplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse);
Constant *C = dyn_cast_or_null<Constant>(V);
return (C && C->isAllOnesValue());
}
/// Return true if we can simplify X / Y to 0. Remainder can adapt that answer
/// to simplify X % Y to X.
static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q,
unsigned MaxRecurse, bool IsSigned) {
// Recursion is always used, so bail out at once if we already hit the limit.
if (!MaxRecurse--)
return false;
if (IsSigned) {
// |X| / |Y| --> 0
//
// We require that 1 operand is a simple constant. That could be extended to
// 2 variables if we computed the sign bit for each.
//
// Make sure that a constant is not the minimum signed value because taking
// the abs() of that is undefined.
Type *Ty = X->getType();
const APInt *C;
if (match(X, m_APInt(C)) && !C->isMinSignedValue()) {
// Is the variable divisor magnitude always greater than the constant
// dividend magnitude?
// |Y| > |C| --> Y < -abs(C) or Y > abs(C)
Constant *PosDividendC = ConstantInt::get(Ty, C->abs());
Constant *NegDividendC = ConstantInt::get(Ty, -C->abs());
if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) ||
isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse))
return true;
}
if (match(Y, m_APInt(C))) {
// Special-case: we can't take the abs() of a minimum signed value. If
// that's the divisor, then all we have to do is prove that the dividend
// is also not the minimum signed value.
if (C->isMinSignedValue())
return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse);
// Is the variable dividend magnitude always less than the constant
// divisor magnitude?
// |X| < |C| --> X > -abs(C) and X < abs(C)
Constant *PosDivisorC = ConstantInt::get(Ty, C->abs());
Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs());
if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) &&
isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse))
return true;
}
return false;
}
// IsSigned == false.
// Is the dividend unsigned less than the divisor?
return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse);
}
/// These are simplifications common to SDiv and UDiv.
static Value *simplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
const SimplifyQuery &Q, unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
return C;
if (Value *V = simplifyDivRem(Op0, Op1, true, Q))
return V;
bool IsSigned = Opcode == Instruction::SDiv;
// (X * Y) / Y -> X if the multiplication does not overflow.
Value *X;
if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) {
auto *Mul = cast<OverflowingBinaryOperator>(Op0);
// If the Mul does not overflow, then we are good to go.
if ((IsSigned && Q.IIQ.hasNoSignedWrap(Mul)) ||
(!IsSigned && Q.IIQ.hasNoUnsignedWrap(Mul)))
return X;
// If X has the form X = A / Y, then X * Y cannot overflow.
if ((IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) ||
(!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1)))))
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;
(void)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;
if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned))
return Constant::getNullValue(Op0->getType());
return nullptr;
}
/// These are simplifications common to SRem and URem.
static Value *simplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
const SimplifyQuery &Q, unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
return C;
if (Value *V = simplifyDivRem(Op0, Op1, false, Q))
return V;
// (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;
// (X << Y) % X -> 0
if (Q.IIQ.UseInstrInfo &&
((Opcode == Instruction::SRem &&
match(Op0, m_NSWShl(m_Specific(Op1), m_Value()))) ||
(Opcode == Instruction::URem &&
match(Op0, m_NUWShl(m_Specific(Op1), m_Value())))))
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;
// If X / Y == 0, then X % Y == X.
if (isDivZero(Op0, Op1, Q, MaxRecurse, Opcode == Instruction::SRem))
return Op0;
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 SimplifyQuery &Q,
unsigned MaxRecurse) {
// If two operands are negated and no signed overflow, return -1.
if (isKnownNegation(Op0, Op1, /*NeedNSW=*/true))
return Constant::getAllOnesValue(Op0->getType());
return simplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse);
}
Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
return ::SimplifySDivInst(Op0, Op1, Q, 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 SimplifyQuery &Q,
unsigned MaxRecurse) {
return simplifyDiv(Instruction::UDiv, Op0, Op1, Q, MaxRecurse);
}
Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
return ::SimplifyUDivInst(Op0, Op1, Q, RecursionLimit);
}
/// 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 SimplifyQuery &Q,
unsigned MaxRecurse) {
// If the divisor is 0, the result is undefined, so assume the divisor is -1.
// srem Op0, (sext i1 X) --> srem Op0, -1 --> 0
Value *X;
if (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))
return ConstantInt::getNullValue(Op0->getType());
// If the two operands are negated, return 0.
if (isKnownNegation(Op0, Op1))
return ConstantInt::getNullValue(Op0->getType());
return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse);
}
Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
return ::SimplifySRemInst(Op0, Op1, Q, 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 SimplifyQuery &Q,
unsigned MaxRecurse) {
return simplifyRem(Instruction::URem, Op0, Op1, Q, MaxRecurse);
}
Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
return ::SimplifyURemInst(Op0, Op1, Q, RecursionLimit);
}
/// Returns true if a shift by \c Amount always yields poison.
static bool isPoisonShift(Value *Amount, const SimplifyQuery &Q) {
Constant *C = dyn_cast<Constant>(Amount);
if (!C)
return false;
// X shift by undef -> poison because it may shift by the bitwidth.
if (Q.isUndefValue(C))
return true;
// Shifting by the bitwidth or more is undefined.
if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
if (CI->getValue().uge(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 = cast<FixedVectorType>(C->getType())->getNumElements();
I != E; ++I)
if (!isPoisonShift(C->getAggregateElement(I), Q))
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(Instruction::BinaryOps Opcode, Value *Op0,
Value *Op1, bool IsNSW, const SimplifyQuery &Q,
unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q))
return C;
// 0 shift by X -> 0
if (match(Op0, m_Zero()))
return Constant::getNullValue(Op0->getType());
// X shift by 0 -> X
// Shift-by-sign-extended bool must be shift-by-0 because shift-by-all-ones
// would be poison.
Value *X;
if (match(Op1, m_Zero()) ||
(match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1)))
return Op0;
// Fold undefined shifts.
if (isPoisonShift(Op1, Q))
return PoisonValue::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.
KnownBits KnownAmt = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (KnownAmt.getMinValue().uge(KnownAmt.getBitWidth()))
return PoisonValue::get(Op0->getType());
// If all valid bits in the shift amount are known zero, the first operand is
// unchanged.
unsigned NumValidShiftBits = Log2_32_Ceil(KnownAmt.getBitWidth());
if (KnownAmt.countMinTrailingZeros() >= NumValidShiftBits)
return Op0;
// Check for nsw shl leading to a poison value.
if (IsNSW) {
assert(Opcode == Instruction::Shl && "Expected shl for nsw instruction");
KnownBits KnownVal = computeKnownBits(Op0, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
KnownBits KnownShl = KnownBits::shl(KnownVal, KnownAmt);
if (KnownVal.Zero.isSignBitSet())
KnownShl.Zero.setSignBit();
if (KnownVal.One.isSignBitSet())
KnownShl.One.setSignBit();
if (KnownShl.hasConflict())
return PoisonValue::get(Op0->getType());
}
return nullptr;
}
/// Given operands for an Shl, LShr or AShr, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyRightShift(Instruction::BinaryOps Opcode, Value *Op0,
Value *Op1, bool isExact, const SimplifyQuery &Q,
unsigned MaxRecurse) {
if (Value *V =
SimplifyShift(Opcode, Op0, Op1, /*IsNSW*/ false, 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 (Q.isUndefValue(Op0))
return isExact ? Op0 : Constant::getNullValue(Op0->getType());
// The low bit cannot be shifted out of an exact shift if it is set.
if (isExact) {
KnownBits Op0Known = computeKnownBits(Op0, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
if (Op0Known.One[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 SimplifyQuery &Q, unsigned MaxRecurse) {
if (Value *V =
SimplifyShift(Instruction::Shl, Op0, Op1, isNSW, Q, MaxRecurse))
return V;
// undef << X -> 0
// undef << X -> undef if (if it's NSW/NUW)
if (Q.isUndefValue(Op0))
return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType());
// (X >> A) << A -> X
Value *X;
if (Q.IIQ.UseInstrInfo &&
match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
return X;
// shl nuw i8 C, %x -> C iff C has sign bit set.
if (isNUW && match(Op0, m_Negative()))
return Op0;
// NOTE: could use computeKnownBits() / LazyValueInfo,
// but the cost-benefit analysis suggests it isn't worth it.
return nullptr;
}
Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
const SimplifyQuery &Q) {
return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, Q, 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 SimplifyQuery &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;
// ((X << A) | Y) >> A -> X if effective width of Y is not larger than A.
// We can return X as we do in the above case since OR alters no bits in X.
// SimplifyDemandedBits in InstCombine can do more general optimization for
// bit manipulation. This pattern aims to provide opportunities for other
// optimizers by supporting a simple but common case in InstSimplify.
Value *Y;
const APInt *ShRAmt, *ShLAmt;
if (match(Op1, m_APInt(ShRAmt)) &&
match(Op0, m_c_Or(m_NUWShl(m_Value(X), m_APInt(ShLAmt)), m_Value(Y))) &&
*ShRAmt == *ShLAmt) {
const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
const unsigned Width = Op0->getType()->getScalarSizeInBits();
const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros();
if (ShRAmt->uge(EffWidthY))
return X;
}
return nullptr;
}
Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
const SimplifyQuery &Q) {
return ::SimplifyLShrInst(Op0, Op1, isExact, Q, 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 SimplifyQuery &Q, unsigned MaxRecurse) {
if (Value *V = SimplifyRightShift(Instruction::AShr, Op0, Op1, isExact, Q,
MaxRecurse))
return V;
// all ones >>a X -> -1
// Do not return Op0 because it may contain undef elements if it's a vector.
if (match(Op0, m_AllOnes()))
return Constant::getAllOnesValue(Op0->getType());
// (X << A) >> A -> X
Value *X;
if (Q.IIQ.UseInstrInfo && 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 SimplifyQuery &Q) {
return ::SimplifyAShrInst(Op0, Op1, isExact, Q, RecursionLimit);
}
/// Commuted variants are assumed to be handled by calling this function again
/// with the parameters swapped.
static Value *simplifyUnsignedRangeCheck(ICmpInst *ZeroICmp,
ICmpInst *UnsignedICmp, bool IsAnd,
const SimplifyQuery &Q) {
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;
Value *A, *B;
// Y = (A - B);
if (match(Y, m_Sub(m_Value(A), m_Value(B)))) {
if (match(UnsignedICmp,
m_c_ICmp(UnsignedPred, m_Specific(A), m_Specific(B))) &&
ICmpInst::isUnsigned(UnsignedPred)) {
// A >=/<= B || (A - B) != 0 <--> true
if ((UnsignedPred == ICmpInst::ICMP_UGE ||
UnsignedPred == ICmpInst::ICMP_ULE) &&
EqPred == ICmpInst::ICMP_NE && !IsAnd)
return ConstantInt::getTrue(UnsignedICmp->getType());
// A </> B && (A - B) == 0 <--> false
if ((UnsignedPred == ICmpInst::ICMP_ULT ||
UnsignedPred == ICmpInst::ICMP_UGT) &&
EqPred == ICmpInst::ICMP_EQ && IsAnd)
return ConstantInt::getFalse(UnsignedICmp->getType());
// A </> B && (A - B) != 0 <--> A </> B
// A </> B || (A - B) != 0 <--> (A - B) != 0
if (EqPred == ICmpInst::ICMP_NE && (UnsignedPred == ICmpInst::ICMP_ULT ||
UnsignedPred == ICmpInst::ICMP_UGT))
return IsAnd ? UnsignedICmp : ZeroICmp;
// A <=/>= B && (A - B) == 0 <--> (A - B) == 0
// A <=/>= B || (A - B) == 0 <--> A <=/>= B
if (EqPred == ICmpInst::ICMP_EQ && (UnsignedPred == ICmpInst::ICMP_ULE ||
UnsignedPred == ICmpInst::ICMP_UGE))
return IsAnd ? ZeroICmp : UnsignedICmp;
}
// Given Y = (A - B)
// Y >= A && Y != 0 --> Y >= A iff B != 0
// Y < A || Y == 0 --> Y < A iff B != 0
if (match(UnsignedICmp,
m_c_ICmp(UnsignedPred, m_Specific(Y), m_Specific(A)))) {
if (UnsignedPred == ICmpInst::ICMP_UGE && IsAnd &&
EqPred == ICmpInst::ICMP_NE &&
isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
return UnsignedICmp;
if (UnsignedPred == ICmpInst::ICMP_ULT && !IsAnd &&
EqPred == ICmpInst::ICMP_EQ &&
isKnownNonZero(B, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
return UnsignedICmp;
}
}
if (match(UnsignedICmp, m_ICmp(UnsignedPred, m_Value(X), m_Specific(Y))) &&
ICmpInst::isUnsigned(UnsignedPred))
;
else if (match(UnsignedICmp,
m_ICmp(UnsignedPred, m_Specific(Y), m_Value(X))) &&
ICmpInst::isUnsigned(UnsignedPred))
UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred);
else
return nullptr;
// X > Y && Y == 0 --> Y == 0 iff X != 0
// X > Y || Y == 0 --> X > Y iff X != 0
if (UnsignedPred == ICmpInst::ICMP_UGT && EqPred == ICmpInst::ICMP_EQ &&
isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
return IsAnd ? ZeroICmp : UnsignedICmp;
// X <= Y && Y != 0 --> X <= Y iff X != 0
// X <= Y || Y != 0 --> Y != 0 iff X != 0
if (UnsignedPred == ICmpInst::ICMP_ULE && EqPred == ICmpInst::ICMP_NE &&
isKnownNonZero(X, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT))
return IsAnd ? UnsignedICmp : ZeroICmp;
// The transforms below here are expected to be handled more generally with
// simplifyAndOrOfICmpsWithLimitConst() or in InstCombine's
// foldAndOrOfICmpsWithConstEq(). If we are looking to trim optimizer overlap,
// these are candidates for removal.
// 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 --> Y == 0
// X >= Y || Y == 0 --> X >= Y
if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_EQ)
return IsAnd ? ZeroICmp : UnsignedICmp;
// X < Y && Y == 0 --> false
if (UnsignedPred == ICmpInst::ICMP_ULT && EqPred == ICmpInst::ICMP_EQ &&
IsAnd)
return getFalse(UnsignedICmp->getType());
// X >= Y || Y != 0 --> true
if (UnsignedPred == ICmpInst::ICMP_UGE && EqPred == ICmpInst::ICMP_NE &&
!IsAnd)
return getTrue(UnsignedICmp->getType());
return nullptr;
}
/// Commuted variants are assumed to be handled by calling this function again
/// with the parameters swapped.
static Value *simplifyAndOfICmpsWithSameOperands(ICmpInst *Op0, ICmpInst *Op1) {
ICmpInst::Predicate Pred0, Pred1;
Value *A ,*B;
if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) ||
!match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B))))
return nullptr;
// We have (icmp Pred0, A, B) & (icmp Pred1, A, B).
// If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we
// can eliminate Op1 from this 'and'.
if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1))
return Op0;
// Check for any combination of predicates that are guaranteed to be disjoint.
if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
(Pred0 == ICmpInst::ICMP_EQ && ICmpInst::isFalseWhenEqual(Pred1)) ||
(Pred0 == ICmpInst::ICMP_SLT && Pred1 == ICmpInst::ICMP_SGT) ||
(Pred0 == ICmpInst::ICMP_ULT && Pred1 == ICmpInst::ICMP_UGT))
return getFalse(Op0->getType());
return nullptr;
}
/// Commuted variants are assumed to be handled by calling this function again
/// with the parameters swapped.
static Value *simplifyOrOfICmpsWithSameOperands(ICmpInst *Op0, ICmpInst *Op1) {
ICmpInst::Predicate Pred0, Pred1;
Value *A ,*B;
if (!match(Op0, m_ICmp(Pred0, m_Value(A), m_Value(B))) ||
!match(Op1, m_ICmp(Pred1, m_Specific(A), m_Specific(B))))
return nullptr;
// We have (icmp Pred0, A, B) | (icmp Pred1, A, B).
// If Op1 is always implied true by Op0, then Op0 is a subset of Op1, and we
// can eliminate Op0 from this 'or'.
if (ICmpInst::isImpliedTrueByMatchingCmp(Pred0, Pred1))
return Op1;
// Check for any combination of predicates that cover the entire range of
// possibilities.
if ((Pred0 == ICmpInst::getInversePredicate(Pred1)) ||
(Pred0 == ICmpInst::ICMP_NE && ICmpInst::isTrueWhenEqual(Pred1)) ||
(Pred0 == ICmpInst::ICMP_SLE && Pred1 == ICmpInst::ICMP_SGE) ||
(Pred0 == ICmpInst::ICMP_ULE && Pred1 == ICmpInst::ICMP_UGE))
return getTrue(Op0->getType());
return nullptr;
}
/// Test if a pair of compares with a shared operand and 2 constants has an
/// empty set intersection, full set union, or if one compare is a superset of
/// the other.
static Value *simplifyAndOrOfICmpsWithConstants(ICmpInst *Cmp0, ICmpInst *Cmp1,
bool IsAnd) {
// Look for this pattern: {and/or} (icmp X, C0), (icmp X, C1)).
if (Cmp0->getOperand(0) != Cmp1->getOperand(0))
return nullptr;
const APInt *C0, *C1;
if (!match(Cmp0->getOperand(1), m_APInt(C0)) ||
!match(Cmp1->getOperand(1), m_APInt(C1)))
return nullptr;
auto Range0 = ConstantRange::makeExactICmpRegion(Cmp0->getPredicate(), *C0);
auto Range1 = ConstantRange::makeExactICmpRegion(Cmp1->getPredicate(), *C1);
// For and-of-compares, check if the intersection is empty:
// (icmp X, C0) && (icmp X, C1) --> empty set --> false
if (IsAnd && Range0.intersectWith(Range1).isEmptySet())
return getFalse(Cmp0->getType());
// For or-of-compares, check if the union is full:
// (icmp X, C0) || (icmp X, C1) --> full set --> true
if (!IsAnd && Range0.unionWith(Range1).isFullSet())
return getTrue(Cmp0->getType());
// Is one range a superset of the other?
// If this is and-of-compares, take the smaller set:
// (icmp sgt X, 4) && (icmp sgt X, 42) --> icmp sgt X, 42
// If this is or-of-compares, take the larger set:
// (icmp sgt X, 4) || (icmp sgt X, 42) --> icmp sgt X, 4
if (Range0.contains(Range1))
return IsAnd ? Cmp1 : Cmp0;
if (Range1.contains(Range0))
return IsAnd ? Cmp0 : Cmp1;
return nullptr;
}
static Value *simplifyAndOrOfICmpsWithZero(ICmpInst *Cmp0, ICmpInst *Cmp1,
bool IsAnd) {
ICmpInst::Predicate P0 = Cmp0->getPredicate(), P1 = Cmp1->getPredicate();
if (!match(Cmp0->getOperand(1), m_Zero()) ||
!match(Cmp1->getOperand(1), m_Zero()) || P0 != P1)
return nullptr;
if ((IsAnd && P0 != ICmpInst::ICMP_NE) || (!IsAnd && P1 != ICmpInst::ICMP_EQ))
return nullptr;
// We have either "(X == 0 || Y == 0)" or "(X != 0 && Y != 0)".
Value *X = Cmp0->getOperand(0);
Value *Y = Cmp1->getOperand(0);
// If one of the compares is a masked version of a (not) null check, then
// that compare implies the other, so we eliminate the other. Optionally, look
// through a pointer-to-int cast to match a null check of a pointer type.
// (X == 0) || (([ptrtoint] X & ?) == 0) --> ([ptrtoint] X & ?) == 0
// (X == 0) || ((? & [ptrtoint] X) == 0) --> (? & [ptrtoint] X) == 0
// (X != 0) && (([ptrtoint] X & ?) != 0) --> ([ptrtoint] X & ?) != 0
// (X != 0) && ((? & [ptrtoint] X) != 0) --> (? & [ptrtoint] X) != 0
if (match(Y, m_c_And(m_Specific(X), m_Value())) ||
match(Y, m_c_And(m_PtrToInt(m_Specific(X)), m_Value())))
return Cmp1;
// (([ptrtoint] Y & ?) == 0) || (Y == 0) --> ([ptrtoint] Y & ?) == 0
// ((? & [ptrtoint] Y) == 0) || (Y == 0) --> (? & [ptrtoint] Y) == 0
// (([ptrtoint] Y & ?) != 0) && (Y != 0) --> ([ptrtoint] Y & ?) != 0
// ((? & [ptrtoint] Y) != 0) && (Y != 0) --> (? & [ptrtoint] Y) != 0
if (match(X, m_c_And(m_Specific(Y), m_Value())) ||
match(X, m_c_And(m_PtrToInt(m_Specific(Y)), m_Value())))
return Cmp0;
return nullptr;
}
static Value *simplifyAndOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1,
const InstrInfoQuery &IIQ) {
// (icmp (add V, C0), C1) & (icmp V, C0)
ICmpInst::Predicate Pred0, Pred1;
const APInt *C0, *C1;
Value *V;
if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
return nullptr;
if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
return nullptr;
auto *AddInst = cast<OverflowingBinaryOperator>(Op0->getOperand(0));
if (AddInst->getOperand(1) != Op1->getOperand(1))
return nullptr;
Type *ITy = Op0->getType();
bool isNSW = IIQ.hasNoSignedWrap(AddInst);
bool isNUW = IIQ.hasNoUnsignedWrap(AddInst);
const APInt Delta = *C1 - *C0;
if (C0->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 (C0->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;
}
/// Try to eliminate compares with signed or unsigned min/max constants.
static Value *simplifyAndOrOfICmpsWithLimitConst(ICmpInst *Cmp0, ICmpInst *Cmp1,
bool IsAnd) {
// Canonicalize an equality compare as Cmp0.
if (Cmp1->isEquality())
std::swap(Cmp0, Cmp1);
if (!Cmp0->isEquality())
return nullptr;
// The non-equality compare must include a common operand (X). Canonicalize
// the common operand as operand 0 (the predicate is swapped if the common
// operand was operand 1).
ICmpInst::Predicate Pred0 = Cmp0->getPredicate();
Value *X = Cmp0->getOperand(0);
ICmpInst::Predicate Pred1;
bool HasNotOp = match(Cmp1, m_c_ICmp(Pred1, m_Not(m_Specific(X)), m_Value()));
if (!HasNotOp && !match(Cmp1, m_c_ICmp(Pred1, m_Specific(X), m_Value())))
return nullptr;
if (ICmpInst::isEquality(Pred1))
return nullptr;
// The equality compare must be against a constant. Flip bits if we matched
// a bitwise not. Convert a null pointer constant to an integer zero value.
APInt MinMaxC;
const APInt *C;
if (match(Cmp0->getOperand(1), m_APInt(C)))
MinMaxC = HasNotOp ? ~*C : *C;
else if (isa<ConstantPointerNull>(Cmp0->getOperand(1)))
MinMaxC = APInt::getNullValue(8);
else
return nullptr;
// DeMorganize if this is 'or': P0 || P1 --> !P0 && !P1.
if (!IsAnd) {
Pred0 = ICmpInst::getInversePredicate(Pred0);
Pred1 = ICmpInst::getInversePredicate(Pred1);
}
// Normalize to unsigned compare and unsigned min/max value.
// Example for 8-bit: -128 + 128 -> 0; 127 + 128 -> 255
if (ICmpInst::isSigned(Pred1)) {
Pred1 = ICmpInst::getUnsignedPredicate(Pred1);
MinMaxC += APInt::getSignedMinValue(MinMaxC.getBitWidth());
}
// (X != MAX) && (X < Y) --> X < Y
// (X == MAX) || (X >= Y) --> X >= Y
if (MinMaxC.isMaxValue())
if (Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_ULT)
return Cmp1;
// (X != MIN) && (X > Y) --> X > Y
// (X == MIN) || (X <= Y) --> X <= Y
if (MinMaxC.isMinValue())
if (Pred0 == ICmpInst::ICMP_NE && Pred1 == ICmpInst::ICMP_UGT)
return Cmp1;
return nullptr;
}
static Value *simplifyAndOfICmps(ICmpInst *Op0, ICmpInst *Op1,
const SimplifyQuery &Q) {
if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/true, Q))
return X;
if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/true, Q))
return X;
if (Value *X = simplifyAndOfICmpsWithSameOperands(Op0, Op1))
return X;
if (Value *X = simplifyAndOfICmpsWithSameOperands(Op1, Op0))
return X;
if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, true))
return X;
if (Value *X = simplifyAndOrOfICmpsWithLimitConst(Op0, Op1, true))
return X;
if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, true))
return X;
if (Value *X = simplifyAndOfICmpsWithAdd(Op0, Op1, Q.IIQ))
return X;
if (Value *X = simplifyAndOfICmpsWithAdd(Op1, Op0, Q.IIQ))
return X;
return nullptr;
}
static Value *simplifyOrOfICmpsWithAdd(ICmpInst *Op0, ICmpInst *Op1,
const InstrInfoQuery &IIQ) {
// (icmp (add V, C0), C1) | (icmp V, C0)
ICmpInst::Predicate Pred0, Pred1;
const APInt *C0, *C1;
Value *V;
if (!match(Op0, m_ICmp(Pred0, m_Add(m_Value(V), m_APInt(C0)), m_APInt(C1))))
return nullptr;
if (!match(Op1, m_ICmp(Pred1, m_Specific(V), m_Value())))
return nullptr;
auto *AddInst = cast<BinaryOperator>(Op0->getOperand(0));
if (AddInst->getOperand(1) != Op1->getOperand(1))
return nullptr;
Type *ITy = Op0->getType();
bool isNSW = IIQ.hasNoSignedWrap(AddInst);
bool isNUW = IIQ.hasNoUnsignedWrap(AddInst);
const APInt Delta = *C1 - *C0;
if (C0->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 (C0->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;
}
static Value *simplifyOrOfICmps(ICmpInst *Op0, ICmpInst *Op1,
const SimplifyQuery &Q) {
if (Value *X = simplifyUnsignedRangeCheck(Op0, Op1, /*IsAnd=*/false, Q))
return X;
if (Value *X = simplifyUnsignedRangeCheck(Op1, Op0, /*IsAnd=*/false, Q))
return X;
if (Value *X = simplifyOrOfICmpsWithSameOperands(Op0, Op1))
return X;
if (Value *X = simplifyOrOfICmpsWithSameOperands(Op1, Op0))
return X;
if (Value *X = simplifyAndOrOfICmpsWithConstants(Op0, Op1, false))
return X;
if (Value *X = simplifyAndOrOfICmpsWithLimitConst(Op0, Op1, false))
return X;
if (Value *X = simplifyAndOrOfICmpsWithZero(Op0, Op1, false))
return X;
if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1, Q.IIQ))
return X;
if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0, Q.IIQ))
return X;
return nullptr;
}
static Value *simplifyAndOrOfFCmps(const TargetLibraryInfo *TLI,
FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) {
Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1);
Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1);
if (LHS0->getType() != RHS0->getType())
return nullptr;
FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate();
if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) ||
(PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) {
// (fcmp ord NNAN, X) & (fcmp ord X, Y) --> fcmp ord X, Y
// (fcmp ord NNAN, X) & (fcmp ord Y, X) --> fcmp ord Y, X
// (fcmp ord X, NNAN) & (fcmp ord X, Y) --> fcmp ord X, Y
// (fcmp ord X, NNAN) & (fcmp ord Y, X) --> fcmp ord Y, X
// (fcmp uno NNAN, X) | (fcmp uno X, Y) --> fcmp uno X, Y
// (fcmp uno NNAN, X) | (fcmp uno Y, X) --> fcmp uno Y, X
// (fcmp uno X, NNAN) | (fcmp uno X, Y) --> fcmp uno X, Y
// (fcmp uno X, NNAN) | (fcmp uno Y, X) --> fcmp uno Y, X
if ((isKnownNeverNaN(LHS0, TLI) && (LHS1 == RHS0 || LHS1 == RHS1)) ||
(isKnownNeverNaN(LHS1, TLI) && (LHS0 == RHS0 || LHS0 == RHS1)))
return RHS;
// (fcmp ord X, Y) & (fcmp ord NNAN, X) --> fcmp ord X, Y
// (fcmp ord Y, X) & (fcmp ord NNAN, X) --> fcmp ord Y, X
// (fcmp ord X, Y) & (fcmp ord X, NNAN) --> fcmp ord X, Y
// (fcmp ord Y, X) & (fcmp ord X, NNAN) --> fcmp ord Y, X
// (fcmp uno X, Y) | (fcmp uno NNAN, X) --> fcmp uno X, Y
// (fcmp uno Y, X) | (fcmp uno NNAN, X) --> fcmp uno Y, X
// (fcmp uno X, Y) | (fcmp uno X, NNAN) --> fcmp uno X, Y
// (fcmp uno Y, X) | (fcmp uno X, NNAN) --> fcmp uno Y, X
if ((isKnownNeverNaN(RHS0, TLI) && (RHS1 == LHS0 || RHS1 == LHS1)) ||
(isKnownNeverNaN(RHS1, TLI) && (RHS0 == LHS0 || RHS0 == LHS1)))
return LHS;
}
return nullptr;
}
static Value *simplifyAndOrOfCmps(const SimplifyQuery &Q,
Value *Op0, Value *Op1, bool IsAnd) {
// Look through casts of the 'and' operands to find compares.
auto *Cast0 = dyn_cast<CastInst>(Op0);
auto *Cast1 = dyn_cast<CastInst>(Op1);
if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() &&
Cast0->getSrcTy() == Cast1->getSrcTy()) {
Op0 = Cast0->getOperand(0);
Op1 = Cast1->getOperand(0);
}
Value *V = nullptr;
auto *ICmp0 = dyn_cast<ICmpInst>(Op0);
auto *ICmp1 = dyn_cast<ICmpInst>(Op1);
if (ICmp0 && ICmp1)
V = IsAnd ? simplifyAndOfICmps(ICmp0, ICmp1, Q)
: simplifyOrOfICmps(ICmp0, ICmp1, Q);
auto *FCmp0 = dyn_cast<FCmpInst>(Op0);
auto *FCmp1 = dyn_cast<FCmpInst>(Op1);
if (FCmp0 && FCmp1)
V = simplifyAndOrOfFCmps(Q.TLI, FCmp0, FCmp1, IsAnd);
if (!V)
return nullptr;
if (!Cast0)
return V;
// If we looked through casts, we can only handle a constant simplification
// because we are not allowed to create a cast instruction here.
if (auto *C = dyn_cast<Constant>(V))
return ConstantExpr::getCast(Cast0->getOpcode(), C, Cast0->getType());
return nullptr;
}
/// Check that the Op1 is in expected form, i.e.:
/// %Agg = tail call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %???)
/// %Op1 = extractvalue { i4, i1 } %Agg, 1
static bool omitCheckForZeroBeforeMulWithOverflowInternal(Value *Op1,
Value *X) {
auto *Extract = dyn_cast<ExtractValueInst>(Op1);
// We should only be extracting the overflow bit.
if (!Extract || !Extract->getIndices().equals(1))
return false;
Value *Agg = Extract->getAggregateOperand();
// This should be a multiplication-with-overflow intrinsic.
if (!match(Agg, m_CombineOr(m_Intrinsic<Intrinsic::umul_with_overflow>(),
m_Intrinsic<Intrinsic::smul_with_overflow>())))
return false;
// One of its multipliers should be the value we checked for zero before.
if (!match(Agg, m_CombineOr(m_Argument<0>(m_Specific(X)),
m_Argument<1>(m_Specific(X)))))
return false;
return true;
}
/// The @llvm.[us]mul.with.overflow intrinsic could have been folded from some
/// other form of check, e.g. one that was using division; it may have been
/// guarded against division-by-zero. We can drop that check now.
/// Look for:
/// %Op0 = icmp ne i4 %X, 0
/// %Agg = tail call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %???)
/// %Op1 = extractvalue { i4, i1 } %Agg, 1
/// %??? = and i1 %Op0, %Op1
/// We can just return %Op1
static Value *omitCheckForZeroBeforeMulWithOverflow(Value *Op0, Value *Op1) {
ICmpInst::Predicate Pred;
Value *X;
if (!match(Op0, m_ICmp(Pred, m_Value(X), m_Zero())) ||
Pred != ICmpInst::Predicate::ICMP_NE)
return nullptr;
// Is Op1 in expected form?
if (!omitCheckForZeroBeforeMulWithOverflowInternal(Op1, X))
return nullptr;
// Can omit 'and', and just return the overflow bit.
return Op1;
}
/// The @llvm.[us]mul.with.overflow intrinsic could have been folded from some
/// other form of check, e.g. one that was using division; it may have been
/// guarded against division-by-zero. We can drop that check now.
/// Look for:
/// %Op0 = icmp eq i4 %X, 0
/// %Agg = tail call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %???)
/// %Op1 = extractvalue { i4, i1 } %Agg, 1
/// %NotOp1 = xor i1 %Op1, true
/// %or = or i1 %Op0, %NotOp1
/// We can just return %NotOp1
static Value *omitCheckForZeroBeforeInvertedMulWithOverflow(Value *Op0,
Value *NotOp1) {
ICmpInst::Predicate Pred;
Value *X;
if (!match(Op0, m_ICmp(Pred, m_Value(X), m_Zero())) ||
Pred != ICmpInst::Predicate::ICMP_EQ)
return nullptr;
// We expect the other hand of an 'or' to be a 'not'.
Value *Op1;
if (!match(NotOp1, m_Not(m_Value(Op1))))
return nullptr;
// Is Op1 in expected form?
if (!omitCheckForZeroBeforeMulWithOverflowInternal(Op1, X))
return nullptr;
// Can omit 'and', and just return the inverted overflow bit.
return NotOp1;
}
/// Given a bitwise logic op, check if the operands are add/sub with a common
/// source value and inverted constant (identity: C - X -> ~(X + ~C)).
static Value *simplifyLogicOfAddSub(Value *Op0, Value *Op1,
Instruction::BinaryOps Opcode) {
assert(Op0->getType() == Op1->getType() && "Mismatched binop types");
assert(BinaryOperator::isBitwiseLogicOp(Opcode) && "Expected logic op");
Value *X;
Constant *C1, *C2;
if ((match(Op0, m_Add(m_Value(X), m_Constant(C1))) &&
match(Op1, m_Sub(m_Constant(C2), m_Specific(X)))) ||
(match(Op1, m_Add(m_Value(X), m_Constant(C1))) &&
match(Op0, m_Sub(m_Constant(C2), m_Specific(X))))) {
if (ConstantExpr::getNot(C1) == C2) {
// (X + C) & (~C - X) --> (X + C) & ~(X + C) --> 0
// (X + C) | (~C - X) --> (X + C) | ~(X + C) --> -1
// (X + C) ^ (~C - X) --> (X + C) ^ ~(X + C) --> -1
Type *Ty = Op0->getType();
return Opcode == Instruction::And ? ConstantInt::getNullValue(Ty)
: ConstantInt::getAllOnesValue(Ty);
}
}
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 SimplifyQuery &Q,
unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q))
return C;
// X & undef -> 0
if (Q.isUndefValue(Op1))
return Constant::getNullValue(Op0->getType());
// X & X = X
if (Op0 == Op1)
return Op0;
// X & 0 = 0
if (match(Op1, m_Zero()))
return Constant::getNullValue(Op0->getType());
// 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
if (match(Op0, m_c_Or(m_Specific(Op1), m_Value())))
return Op1;
// A & (A | ?) = A
if (match(Op1, m_c_Or(m_Specific(Op0), m_Value())))
return Op0;
if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::And))
return V;
// A mask that only clears known zeros of a shifted value is a no-op.
Value *X;
const APInt *Mask;
const APInt *ShAmt;
if (match(Op1, m_APInt(Mask))) {
// If all bits in the inverted and shifted mask are clear:
// and (shl X, ShAmt), Mask --> shl X, ShAmt
if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) &&
(~(*Mask)).lshr(*ShAmt).isNullValue())
return Op0;
// If all bits in the inverted and shifted mask are clear:
// and (lshr X, ShAmt), Mask --> lshr X, ShAmt
if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) &&
(~(*Mask)).shl(*ShAmt).isNullValue())
return Op0;
}
// If we have a multiplication overflow check that is being 'and'ed with a
// check that one of the multipliers is not zero, we can omit the 'and', and
// only keep the overflow check.
if (Value *V = omitCheckForZeroBeforeMulWithOverflow(Op0, Op1))
return V;
if (Value *V = omitCheckForZeroBeforeMulWithOverflow(Op1, Op0))
return V;
// 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;
}
// This is a similar pattern used for checking if a value is a power-of-2:
// (A - 1) & A --> 0 (if A is a power-of-2 or 0)
// A & (A - 1) --> 0 (if A is a power-of-2 or 0)
if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) &&
isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT))
return Constant::getNullValue(Op1->getType());
if (match(Op1, m_Add(m_Specific(Op0), m_AllOnes())) &&
isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT))
return Constant::getNullValue(Op0->getType());
if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, true))
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 = expandCommutativeBinOp(Instruction::And, Op0, Op1,
Instruction::Or, Q, MaxRecurse))
return V;
// And distributes over Xor. Try some generic simplifications based on this.
if (Value *V = expandCommutativeBinOp(Instruction::And, Op0, Op1,
Instruction::Xor, Q, MaxRecurse))
return V;
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) {
if (Op0->getType()->isIntOrIntVectorTy(1)) {
// A & (A && B) -> A && B
if (match(Op1, m_Select(m_Specific(Op0), m_Value(), m_Zero())))
return Op1;
else if (match(Op0, m_Select(m_Specific(Op1), m_Value(), m_Zero())))
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 (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;
// Assuming the effective width of Y is not larger than A, i.e. all bits
// from X and Y are disjoint in (X << A) | Y,
// if the mask of this AND op covers all bits of X or Y, while it covers
// no bits from the other, we can bypass this AND op. E.g.,
// ((X << A) | Y) & Mask -> Y,
// if Mask = ((1 << effective_width_of(Y)) - 1)
// ((X << A) | Y) & Mask -> X << A,
// if Mask = ((1 << effective_width_of(X)) - 1) << A
// SimplifyDemandedBits in InstCombine can optimize the general case.
// This pattern aims to help other passes for a common case.
Value *Y, *XShifted;
if (match(Op1, m_APInt(Mask)) &&
match(Op0, m_c_Or(m_CombineAnd(m_NUWShl(m_Value(X), m_APInt(ShAmt)),
m_Value(XShifted)),
m_Value(Y)))) {
const unsigned Width = Op0->getType()->getScalarSizeInBits();
const unsigned ShftCnt = ShAmt->getLimitedValue(Width);
const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros();
if (EffWidthY <= ShftCnt) {
const KnownBits XKnown = computeKnownBits(X, Q.DL, 0, Q.AC, Q.CxtI,
Q.DT);
const unsigned EffWidthX = Width - XKnown.countMinLeadingZeros();
const APInt EffBitsY = APInt::getLowBitsSet(Width, EffWidthY);
const APInt EffBitsX = APInt::getLowBitsSet(Width, EffWidthX) << ShftCnt;
// If the mask is extracting all bits from X or Y as is, we can skip
// this AND op.
if (EffBitsY.isSubsetOf(*Mask) && !EffBitsX.intersects(*Mask))
return Y;
if (EffBitsX.isSubsetOf(*Mask) && !EffBitsY.intersects(*Mask))
return XShifted;
}
}
return nullptr;
}
Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) {
return ::SimplifyAndInst(Op0, Op1, Q, RecursionLimit);
}
/// 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 SimplifyQuery &Q,
unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q))
return C;
// X | undef -> -1
// X | -1 = -1
// Do not return Op1 because it may contain undef elements if it's a vector.
if (Q.isUndefValue(Op1) || match(Op1, m_AllOnes()))
return Constant::getAllOnesValue(Op0->getType());
// X | X = X
// X | 0 = X
if (Op0 == Op1 || match(Op1, m_Zero()))
return Op0;
// 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
if (match(Op0, m_c_And(m_Specific(Op1), m_Value())))
return Op1;
// A | (A & ?) = A
if (match(Op1, m_c_And(m_Specific(Op0), m_Value())))
return Op0;
// ~(A & ?) | A = -1
if (match(Op0, m_Not(m_c_And(m_Specific(Op1), m_Value()))))
return Constant::getAllOnesValue(Op1->getType());
// A | ~(A & ?) = -1
if (match(Op1, m_Not(m_c_And(m_Specific(Op0), m_Value()))))
return Constant::getAllOnesValue(Op0->getType());
if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Or))
return V;
Value *A, *B, *NotA;
// (A & ~B) | (A ^ B) -> (A ^ B)
// (~B & A) | (A ^ B) -> (A ^ B)
// (A & ~B) | (B ^ A) -> (B ^ A)
// (~B & A) | (B ^ A) -> (B ^ A)
if (match(Op1, m_Xor(m_Value(A), m_Value(B))) &&
(match(Op0, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
match(Op0, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
return Op1;
// Commute the 'or' operands.
// (A ^ B) | (A & ~B) -> (A ^ B)
// (A ^ B) | (~B & A) -> (A ^ B)
// (B ^ A) | (A & ~B) -> (B ^ A)
// (B ^ A) | (~B & A) -> (B ^ A)
if (match(Op0, m_Xor(m_Value(A), m_Value(B))) &&
(match(Op1, m_c_And(m_Specific(A), m_Not(m_Specific(B)))) ||
match(Op1, m_c_And(m_Not(m_Specific(A)), m_Specific(B)))))
return Op0;
// (A & B) | (~A ^ B) -> (~A ^ B)
// (B & A) | (~A ^ B) -> (~A ^ B)
// (A & B) | (B ^ ~A) -> (B ^ ~A)
// (B & A) | (B ^ ~A) -> (B ^ ~A)
if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
(match(Op1, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) ||
match(Op1, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
return Op1;
// Commute the 'or' operands.
// (~A ^ B) | (A & B) -> (~A ^ B)
// (~A ^ B) | (B & A) -> (~A ^ B)
// (B ^ ~A) | (A & B) -> (B ^ ~A)
// (B ^ ~A) | (B & A) -> (B ^ ~A)
if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
(match(Op0, m_c_Xor(m_Specific(A), m_Not(m_Specific(B)))) ||
match(Op0, m_c_Xor(m_Not(m_Specific(A)), m_Specific(B)))))
return Op0;
// (~A & B) | ~(A | B) --> ~A
// (~A & B) | ~(B | A) --> ~A
// (B & ~A) | ~(A | B) --> ~A
// (B & ~A) | ~(B | A) --> ~A
if (match(Op0, m_c_And(m_CombineAnd(m_Value(NotA), m_Not(m_Value(A))),
m_Value(B))) &&
match(Op1, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
return NotA;
// Commute the 'or' operands.
// ~(A | B) | (~A & B) --> ~A
// ~(B | A) | (~A & B) --> ~A
// ~(A | B) | (B & ~A) --> ~A
// ~(B | A) | (B & ~A) --> ~A
if (match(Op1, m_c_And(m_CombineAnd(m_Value(NotA), m_Not(m_Value(A))),
m_Value(B))) &&
match(Op0, m_Not(m_c_Or(m_Specific(A), m_Specific(B)))))
return NotA;
if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, false))
return V;
// If we have a multiplication overflow check that is being 'and'ed with a
// check that one of the multipliers is not zero, we can omit the 'and', and
// only keep the overflow check.
if (Value *V = omitCheckForZeroBeforeInvertedMulWithOverflow(Op0, Op1))
return V;
if (Value *V = omitCheckForZeroBeforeInvertedMulWithOverflow(Op1, Op0))
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 = expandCommutativeBinOp(Instruction::Or, Op0, Op1,
Instruction::And, Q, MaxRecurse))
return V;
if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) {
if (Op0->getType()->isIntOrIntVectorTy(1)) {
// A | (A || B) -> A || B
if (match(Op1, m_Select(m_Specific(Op0), m_One(), m_Value())))
return Op1;
else if (match(Op0, m_Select(m_Specific(Op1), m_One(), m_Value())))
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 (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q,
MaxRecurse))
return V;
}
// (A & C1)|(B & C2)
const APInt *C1, *C2;
if (match(Op0, m_And(m_Value(A), m_APInt(C1))) &&
match(Op1, m_And(m_Value(B), m_APInt(C2)))) {
if (*C1 == ~*C2) {
// (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 *N;
if (C2->isMask() && // C2 == 0+1+
match(A, m_c_Add(m_Specific(B), m_Value(N)))) {
// Add commutes, try both ways.
if (MaskedValueIsZero(N, *C2, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return A;
}
// Or commutes, try both ways.
if (C1->isMask() &&
match(B, m_c_Add(m_Specific(A), m_Value(N)))) {
// Add commutes, try both ways.
if (MaskedValueIsZero(N, *C1, 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 SimplifyQuery &Q) {
return ::SimplifyOrInst(Op0, Op1, Q, 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 SimplifyQuery &Q,
unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Instruction::Xor, Op0, Op1, Q))
return C;
// A ^ undef -> undef
if (Q.isUndefValue(Op1))
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());
if (Value *V = simplifyLogicOfAddSub(Op0, Op1, Instruction::Xor))
return V;
// 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 SimplifyQuery &Q) {
return ::SimplifyXorInst(Op0, Op1, Q, 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(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
const SimplifyQuery &Q) {
const DataLayout &DL = Q.DL;
const TargetLibraryInfo *TLI = Q.TLI;
const DominatorTree *DT = Q.DT;
const Instruction *CxtI = Q.CxtI;
const InstrInfoQuery &IIQ = Q.IIQ;
// 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 (isa<ConstantPointerNull>(RHS) && ICmpInst::isEquality(Pred) &&
llvm::isKnownNonZero(LHS, DL, 0, nullptr, nullptr, nullptr,
IIQ.UseInstrInfo))
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;
ObjectSizeOpts Opts;
Opts.NullIsUnknownSize =
NullPointerIsDefined(cast<AllocaInst>(LHS)->getFunction());
if (LHSOffsetCI && RHSOffsetCI &&
getObjectSize(LHS, LHSSize, DL, TLI, Opts) &&
getObjectSize(RHS, RHSSize, DL, TLI, Opts)) {
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<const Value *, 8> LHSUObjs, RHSUObjs;
getUnderlyingObjects(LHS, LHSUObjs);
getUnderlyingObjects(RHS, RHSUObjs);
// Is the set of underlying objects all noalias calls?
auto IsNAC = [](ArrayRef<const Value *> Objects) {
return all_of(Objects, 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 = [](ArrayRef<const Value *> Objects) {
return all_of(Objects, [](const 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->hasGlobalUnnamedAddr()) &&
!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::isKnownNonZero(RHS, DL, 0, nullptr, CxtI, DT))
MI = LHS;
else if (isAllocLikeFn(RHS, TLI) &&
llvm::isKnownNonZero(LHS, DL, 0, nullptr, CxtI, DT))
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;
}
/// Fold an icmp when its operands have i1 scalar type.
static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const SimplifyQuery &Q) {
Type *ITy = GetCompareTy(LHS); // The return type.
Type *OpTy = LHS->getType(); // The operand type.
if (!OpTy->isIntOrIntVectorTy(1))
return nullptr;
// A boolean compared to true/false can be simplified in 14 out of the 20
// (10 predicates * 2 constants) possible combinations. Cases not handled here
// require a 'not' of the LHS, so those must be transformed in InstCombine.
if (match(RHS, m_Zero())) {
switch (Pred) {
case CmpInst::ICMP_NE: // X != 0 -> X
case CmpInst::ICMP_UGT: // X >u 0 -> X
case CmpInst::ICMP_SLT: // X <s 0 -> X
return LHS;
case CmpInst::ICMP_ULT: // X <u 0 -> false
case CmpInst::ICMP_SGT: // X >s 0 -> false
return getFalse(ITy);
case CmpInst::ICMP_UGE: // X >=u 0 -> true
case CmpInst::ICMP_SLE: // X <=s 0 -> true
return getTrue(ITy);
default: break;
}
} else if (match(RHS, m_One())) {
switch (Pred) {
case CmpInst::ICMP_EQ: // X == 1 -> X
case CmpInst::ICMP_UGE: // X >=u 1 -> X
case CmpInst::ICMP_SLE: // X <=s -1 -> X
return LHS;
case CmpInst::ICMP_UGT: // X >u 1 -> false
case CmpInst::ICMP_SLT: // X <s -1 -> false
return getFalse(ITy);
case CmpInst::ICMP_ULE: // X <=u 1 -> true
case CmpInst::ICMP_SGE: // X >=s -1 -> true
return getTrue(ITy);
default: break;
}
}
switch (Pred) {
default:
break;
case ICmpInst::ICMP_UGE:
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_ULE:
if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
return getTrue(ITy);
break;
}
return nullptr;
}
/// Try hard to fold icmp with zero RHS because this is a common case.
static Value *simplifyICmpWithZero(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const SimplifyQuery &Q) {
if (!match(RHS, m_Zero()))
return nullptr;
Type *ITy = GetCompareTy(LHS); // The return type.
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, Q.IIQ.UseInstrInfo))
return getFalse(ITy);
break;
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_UGT:
if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo))
return getTrue(ITy);
break;
case ICmpInst::ICMP_SLT: {
KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (LHSKnown.isNegative())
return getTrue(ITy);
if (LHSKnown.isNonNegative())
return getFalse(ITy);
break;
}
case ICmpInst::ICMP_SLE: {
KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (LHSKnown.isNegative())
return getTrue(ITy);
if (LHSKnown.isNonNegative() &&
isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getFalse(ITy);
break;
}
case ICmpInst::ICMP_SGE: {
KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (LHSKnown.isNegative())
return getFalse(ITy);
if (LHSKnown.isNonNegative())
return getTrue(ITy);
break;
}
case ICmpInst::ICMP_SGT: {
KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (LHSKnown.isNegative())
return getFalse(ITy);
if (LHSKnown.isNonNegative() &&
isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getTrue(ITy);
break;
}
}
return nullptr;
}
static Value *simplifyICmpWithConstant(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const InstrInfoQuery &IIQ) {
Type *ITy = GetCompareTy(RHS); // The return type.
Value *X;
// Sign-bit checks can be optimized to true/false after unsigned
// floating-point casts:
// icmp slt (bitcast (uitofp X)), 0 --> false
// icmp sgt (bitcast (uitofp X)), -1 --> true
if (match(LHS, m_BitCast(m_UIToFP(m_Value(X))))) {
if (Pred == ICmpInst::ICMP_SLT && match(RHS, m_Zero()))
return ConstantInt::getFalse(ITy);
if (Pred == ICmpInst::ICMP_SGT && match(RHS, m_AllOnes()))
return ConstantInt::getTrue(ITy);
}
const APInt *C;
if (!match(RHS, m_APIntAllowUndef(C)))
return nullptr;
// Rule out tautological comparisons (eg., ult 0 or uge 0).
ConstantRange RHS_CR = ConstantRange::makeExactICmpRegion(Pred, *C);
if (RHS_CR.isEmptySet())
return ConstantInt::getFalse(ITy);
if (RHS_CR.isFullSet())
return ConstantInt::getTrue(ITy);
ConstantRange LHS_CR = computeConstantRange(LHS, IIQ.UseInstrInfo);
if (!LHS_CR.isFullSet()) {
if (RHS_CR.contains(LHS_CR))
return ConstantInt::getTrue(ITy);
if (RHS_CR.inverse().contains(LHS_CR))
return ConstantInt::getFalse(ITy);
}
// (mul nuw/nsw X, MulC) != C --> true (if C is not a multiple of MulC)
// (mul nuw/nsw X, MulC) == C --> false (if C is not a multiple of MulC)
const APInt *MulC;
if (ICmpInst::isEquality(Pred) &&
((match(LHS, m_NUWMul(m_Value(), m_APIntAllowUndef(MulC))) &&
*MulC != 0 && C->urem(*MulC) != 0) ||
(match(LHS, m_NSWMul(m_Value(), m_APIntAllowUndef(MulC))) &&
*MulC != 0 && C->srem(*MulC) != 0)))
return ConstantInt::get(ITy, Pred == ICmpInst::ICMP_NE);
return nullptr;
}
static Value *simplifyICmpWithBinOpOnLHS(
CmpInst::Predicate Pred, BinaryOperator *LBO, Value *RHS,
const SimplifyQuery &Q, unsigned MaxRecurse) {
Type *ITy = GetCompareTy(RHS); // The return type.
Value *Y = nullptr;
// icmp pred (or X, Y), X
if (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) {
KnownBits RHSKnown = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (RHSKnown.isNonNegative() && YKnown.isNegative())
return Pred == ICmpInst::ICMP_SLT ? getTrue(ITy) : getFalse(ITy);
if (RHSKnown.isNegative() || YKnown.isNonNegative())
return Pred == ICmpInst::ICMP_SLT ? getFalse(ITy) : getTrue(ITy);
}
}
// icmp pred (and X, Y), X
if (match(LBO, m_c_And(m_Value(), m_Specific(RHS)))) {
if (Pred == ICmpInst::ICMP_UGT)
return getFalse(ITy);
if (Pred == ICmpInst::ICMP_ULE)
return getTrue(ITy);
}
// icmp pred (urem X, Y), Y
if (match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
switch (Pred) {
default:
break;
case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE: {
KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (!Known.isNonNegative())
break;
LLVM_FALLTHROUGH;
}
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
return getFalse(ITy);
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_SLE: {
KnownBits Known = computeKnownBits(RHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT);
if (!Known.isNonNegative())
break;
LLVM_FALLTHROUGH;
}
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_ULE:
return getTrue(ITy);
}
}
// icmp pred (urem X, Y), X
if (match(LBO, m_URem(m_Specific(RHS), m_Value()))) {
if (Pred == ICmpInst::ICMP_ULE)
return getTrue(ITy);
if (Pred == ICmpInst::ICMP_UGT)
return getFalse(ITy);
}
// x >> y <=u x
// x udiv y <=u x.
if (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);
}
// (x*C1)/C2 <= x for C1 <= C2.
// This holds even if the multiplication overflows: Assume that x != 0 and
// arithmetic is modulo M. For overflow to occur we must have C1 >= M/x and
// thus C2 >= M/x. It follows that (x*C1)/C2 <= (M-1)/C2 <= ((M-1)*x)/M < x.
//
// Additionally, either the multiplication and division might be represented
// as shifts:
// (x*C1)>>C2 <= x for C1 < 2**C2.
// (x<<C1)/C2 <= x for 2**C1 < C2.
const APInt *C1, *C2;
if ((match(LBO, m_UDiv(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) &&
C1->ule(*C2)) ||
(match(LBO, m_LShr(m_Mul(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) &&
C1->ule(APInt(C2->getBitWidth(), 1) << *C2)) ||
(match(LBO, m_UDiv(m_Shl(m_Specific(RHS), m_APInt(C1)), m_APInt(C2))) &&
(APInt(C1->getBitWidth(), 1) << *C1).ule(*C2))) {
if (Pred == ICmpInst::ICMP_UGT)
return getFalse(ITy);
if (Pred == ICmpInst::ICMP_ULE)
return getTrue(ITy);
}
return nullptr;
}
// If only one of the icmp's operands has NSW flags, try to prove that:
//
// icmp slt (x + C1), (x +nsw C2)
//
// is equivalent to:
//
// icmp slt C1, C2
//
// which is true if x + C2 has the NSW flags set and:
// *) C1 < C2 && C1 >= 0, or
// *) C2 < C1 && C1 <= 0.
//
static bool trySimplifyICmpWithAdds(CmpInst::Predicate Pred, Value *LHS,
Value *RHS) {
// TODO: only support icmp slt for now.
if (Pred != CmpInst::ICMP_SLT)
return false;
// Canonicalize nsw add as RHS.
if (!match(RHS, m_NSWAdd(m_Value(), m_Value())))
std::swap(LHS, RHS);
if (!match(RHS, m_NSWAdd(m_Value(), m_Value())))
return false;
Value *X;
const APInt *C1, *C2;
if (!match(LHS, m_c_Add(m_Value(X), m_APInt(C1))) ||
!match(RHS, m_c_Add(m_Specific(X), m_APInt(C2))))
return false;
return (C1->slt(*C2) && C1->isNonNegative()) ||
(C2->slt(*C1) && C1->isNonPositive());
}
/// TODO: A large part of this logic is duplicated in InstCombine's
/// foldICmpBinOp(). We should be able to share that and avoid the code
/// duplication.
static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const SimplifyQuery &Q,
unsigned MaxRecurse) {
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) &&
Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO))) ||
(CmpInst::isSigned(Pred) &&
Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)));
}
if (RBO && RBO->getOpcode() == Instruction::Add) {
C = RBO->getOperand(0);
D = RBO->getOperand(1);
NoRHSWrapProblem =
ICmpInst::isEquality(Pred) ||
(CmpInst::isUnsigned(Pred) &&
Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(RBO))) ||
(CmpInst::isSigned(Pred) &&
Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(RBO)));
}
// 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.
bool CanSimplify = (NoLHSWrapProblem && NoRHSWrapProblem) ||
trySimplifyICmpWithAdds(Pred, LHS, RHS);
if (A && C && (A == C || A == D || B == C || B == D) && CanSimplify) {
// 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;
}
}
if (LBO)
if (Value *V = simplifyICmpWithBinOpOnLHS(Pred, LBO, RHS, Q, MaxRecurse))
return V;
if (RBO)
if (Value *V = simplifyICmpWithBinOpOnLHS(
ICmpInst::getSwappedPredicate(Pred), RBO, LHS, Q, MaxRecurse))
return V;
// 0 - (zext X) pred C
if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) {
const APInt *C;
if (match(RHS, m_APInt(C))) {
if (C->isStrictlyPositive()) {
if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_NE)
return ConstantInt::getTrue(GetCompareTy(RHS));
if (Pred == ICmpInst::ICMP_SGE || Pred == ICmpInst::ICMP_EQ)
return ConstantInt::getFalse(GetCompareTy(RHS));
}
if (C->isNonNegative()) {
if (Pred == ICmpInst::ICMP_SLE)
return ConstantInt::getTrue(GetCompareTy(RHS));
if (Pred == ICmpInst::ICMP_SGT)
return ConstantInt::getFalse(GetCompareTy(RHS));
}
}
}
// If C2 is a power-of-2 and C is not:
// (C2 << X) == C --> false
// (C2 << X) != C --> true
const APInt *C;
if (match(LHS, m_Shl(m_Power2(), m_Value())) &&
match(RHS, m_APIntAllowUndef(C)) && !C->isPowerOf2()) {
// C2 << X can equal zero in some circumstances.
// This simplification might be unsafe if C 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.
// - C2 is one.
// - C isn't zero.
if (Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)) ||
Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO)) ||
match(LHS, m_Shl(m_One(), m_Value())) || !C->isNullValue()) {
if (Pred == ICmpInst::ICMP_EQ)
return ConstantInt::getFalse(GetCompareTy(RHS));
if (Pred == ICmpInst::ICMP_NE)
return ConstantInt::getTrue(GetCompareTy(RHS));
}
}
// TODO: This is overly constrained. LHS can be any power-of-2.
// (1 << X) >u 0x8000 --> false
// (1 << X) <=u 0x8000 --> true
if (match(LHS, m_Shl(m_One(), m_Value())) && match(RHS, m_SignMask())) {
if (Pred == ICmpInst::ICMP_UGT)
return ConstantInt::getFalse(GetCompareTy(RHS));
if (Pred == ICmpInst::ICMP_ULE)
return ConstantInt::getTrue(GetCompareTy(RHS));
}
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) || !Q.IIQ.isExact(LBO) ||
!Q.IIQ.isExact(RBO))
break;
if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
RBO->getOperand(0), Q, MaxRecurse - 1))
return V;
break;
case Instruction::SDiv:
if (!ICmpInst::isEquality(Pred) || !Q.IIQ.isExact(LBO) ||
!Q.IIQ.isExact(RBO))
break;
if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
RBO->getOperand(0), Q, MaxRecurse - 1))
return V;
break;
case Instruction::AShr:
if (!Q.IIQ.isExact(LBO) || !Q.IIQ.isExact(RBO))
break;
if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
RBO->getOperand(0), Q, MaxRecurse - 1))
return V;
break;
case Instruction::Shl: {
bool NUW = Q.IIQ.hasNoUnsignedWrap(LBO) && Q.IIQ.hasNoUnsignedWrap(RBO);
bool NSW = Q.IIQ.hasNoSignedWrap(LBO) && Q.IIQ.hasNoSignedWrap(RBO);
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;
}
}
}
return nullptr;
}
/// Simplify integer comparisons where at least one operand of the compare
/// matches an integer min/max idiom.
static Value *simplifyICmpWithMinMax(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const SimplifyQuery &Q,
unsigned MaxRecurse) {
Type *ITy = GetCompareTy(LHS); // The return type.
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:
return getTrue(ITy);
case CmpInst::ICMP_ULT:
return getFalse(ITy);
}
}
// Comparing 1 each of min/max with a common operand?
// Canonicalize min operand to RHS.
if (match(LHS, m_UMin(m_Value(), m_Value())) ||
match(LHS, m_SMin(m_Value(), m_Value()))) {
std::swap(LHS, RHS);
Pred = ICmpInst::getSwappedPredicate(Pred);
}
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)) {
// smax(A, B) >=s smin(A, D) --> true
if (Pred == CmpInst::ICMP_SGE)
return getTrue(ITy);
// smax(A, B) <s smin(A, D) --> false
if (Pred == CmpInst::ICMP_SLT)
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)) {
// umax(A, B) >=u umin(A, D) --> true
if (Pred == CmpInst::ICMP_UGE)
return getTrue(ITy);
// umax(A, B) <u umin(A, D) --> false
if (Pred == CmpInst::ICMP_ULT)
return getFalse(ITy);
}
return nullptr;
}
static Value *simplifyICmpWithDominatingAssume(CmpInst::Predicate Predicate,
Value *LHS, Value *RHS,
const SimplifyQuery &Q) {
// Gracefully handle instructions that have not been inserted yet.
if (!Q.AC || !Q.CxtI || !Q.CxtI->getParent())
return nullptr;
for (Value *AssumeBaseOp : {LHS, RHS}) {
for (auto &AssumeVH : Q.AC->assumptionsFor(AssumeBaseOp)) {
if (!AssumeVH)
continue;
CallInst *Assume = cast<CallInst>(AssumeVH);
if (Optional<bool> Imp =
isImpliedCondition(Assume->getArgOperand(0), Predicate, LHS, RHS,
Q.DL))
if (isValidAssumeForContext(Assume, Q.CxtI, Q.DT))
return ConstantInt::get(GetCompareTy(LHS), *Imp);
}
}
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 SimplifyQuery &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);
}
assert(!isa<UndefValue>(LHS) && "Unexpected icmp undef,%X");
Type *ITy = GetCompareTy(LHS); // The return type.
// For EQ and NE, we can always pick a value for the undef to make the
// predicate pass or fail, so we can return undef.
// Matches behavior in llvm::ConstantFoldCompareInstruction.
if (Q.isUndefValue(RHS) && ICmpInst::isEquality(Pred))
return UndefValue::get(ITy);
// icmp X, X -> true/false
// icmp X, undef -> true/false because undef could be X.
if (LHS == RHS || Q.isUndefValue(RHS))
return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q))
return V;
if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q))
return V;
if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q.IIQ))
return V;
// If both operands have range metadata, use the metadata
// to simplify the comparison.
if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) {
auto RHS_Instr = cast<Instruction>(RHS);
auto LHS_Instr = cast<Instruction>(LHS);
if (Q.IIQ.getMetadata(RHS_Instr, LLVMContext::MD_range) &&
Q.IIQ.getMetadata(LHS_Instr, 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;
}
// Fold (zext X) ule (sext X), (zext X) sge (sext X) to true.
else if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
if (SrcOp == RI->getOperand(0)) {
if (Pred == ICmpInst::ICMP_ULE || Pred == ICmpInst::ICMP_SGE)
return ConstantInt::getTrue(ITy);
if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SLT)
return ConstantInt::getFalse(ITy);
}
}
// 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;
}
// Fold (sext X) uge (zext X), (sext X) sle (zext X) to true.
else if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
if (SrcOp == RI->getOperand(0)) {
if (Pred == ICmpInst::ICMP_UGE || Pred == ICmpInst::ICMP_SLE)
return ConstantInt::getTrue(ITy);
if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SGT)
return ConstantInt::getFalse(ITy);
}
}
// 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 (ICmpInst::isEquality(Pred) &&
isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) {
return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy);
}
if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse))
return V;
if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse))
return V;
if (Value *V = simplifyICmpWithDominatingAssume(Pred, LHS, RHS, Q))
return V;
// 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(Pred, LHS, RHS, Q))
return C;
if (auto *CLHS = dyn_cast<PtrToIntOperator>(LHS))
if (auto *CRHS = dyn_cast<PtrToIntOperator>(RHS))
if (Q.DL.getTypeSizeInBits(CLHS->getPointerOperandType()) ==
Q.DL.getTypeSizeInBits(CLHS->getType()) &&
Q.DL.getTypeSizeInBits(CRHS->getPointerOperandType()) ==
Q.DL.getTypeSizeInBits(CRHS->getType()))
if (auto *C = computePointerICmp(Pred, CLHS->getPointerOperand(),
CRHS->getPointerOperand(), Q))
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->indices());
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);
Constant *NewICmp = ConstantExpr::getICmp(Pred, NewLHS, NewRHS);
return ConstantFoldConstant(NewICmp, Q.DL);
}
}
}
// 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 SimplifyQuery &Q) {
return ::SimplifyICmpInst(Predicate, LHS, RHS, Q, 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 SimplifyQuery &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.
Type *RetTy = GetCompareTy(LHS);
if (Pred == FCmpInst::FCMP_FALSE)
return getFalse(RetTy);
if (Pred == FCmpInst::FCMP_TRUE)
return getTrue(RetTy);
// Fold (un)ordered comparison if we can determine there are no NaNs.
if (Pred == FCmpInst::FCMP_UNO || Pred == FCmpInst::FCMP_ORD)
if (FMF.noNaNs() ||
(isKnownNeverNaN(LHS, Q.TLI) && isKnownNeverNaN(RHS, Q.TLI)))
return ConstantInt::get(RetTy, Pred == FCmpInst::FCMP_ORD);
// NaN is unordered; NaN is not ordered.
assert((FCmpInst::isOrdered(Pred) || FCmpInst::isUnordered(Pred)) &&
"Comparison must be either ordered or unordered");
if (match(RHS, m_NaN()))
return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred));
// fcmp pred x, undef and fcmp pred undef, x
// fold to true if unordered, false if ordered
if (Q.isUndefValue(LHS) || Q.isUndefValue(RHS)) {
// Choosing NaN for the undef will always make unordered comparison succeed
// and ordered comparison fail.
return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred));
}
// fcmp x,x -> true/false. Not all compares are foldable.
if (LHS == RHS) {
if (CmpInst::isTrueWhenEqual(Pred))
return getTrue(RetTy);
if (CmpInst::isFalseWhenEqual(Pred))
return getFalse(RetTy);
}
// Handle fcmp with constant RHS.
// TODO: Use match with a specific FP value, so these work with vectors with
// undef lanes.
const APFloat *C;
if (match(RHS, m_APFloat(C))) {
// Check whether the constant is an infinity.
if (C->isInfinity()) {
if (C->isNegative()) {
switch (Pred) {
case FCmpInst::FCMP_OLT:
// No value is ordered and less than negative infinity.
return getFalse(RetTy);
case FCmpInst::FCMP_UGE:
// All values are unordered with or at least negative infinity.
return getTrue(RetTy);
default:
break;
}
} else {
switch (Pred) {
case FCmpInst::FCMP_OGT:
// No value is ordered and greater than infinity.
return getFalse(RetTy);
case FCmpInst::FCMP_ULE:
// All values are unordered with and at most infinity.
return getTrue(RetTy);
default:
break;
}
}
// LHS == Inf
if (Pred == FCmpInst::FCMP_OEQ && isKnownNeverInfinity(LHS, Q.TLI))
return getFalse(RetTy);
// LHS != Inf
if (Pred == FCmpInst::FCMP_UNE && isKnownNeverInfinity(LHS, Q.TLI))
return getTrue(RetTy);
// LHS == Inf || LHS == NaN
if (Pred == FCmpInst::FCMP_UEQ && isKnownNeverInfinity(LHS, Q.TLI) &&
isKnownNeverNaN(LHS, Q.TLI))
return getFalse(RetTy);
// LHS != Inf && LHS != NaN
if (Pred == FCmpInst::FCMP_ONE && isKnownNeverInfinity(LHS, Q.TLI) &&
isKnownNeverNaN(LHS, Q.TLI))
return getTrue(RetTy);
}
if (C->isNegative() && !C->isNegZero()) {
assert(!C->isNaN() && "Unexpected NaN constant!");
// TODO: We can catch more cases by using a range check rather than
// relying on CannotBeOrderedLessThanZero.
switch (Pred) {
case FCmpInst::FCMP_UGE:
case FCmpInst::FCMP_UGT:
case FCmpInst::FCMP_UNE:
// (X >= 0) implies (X > C) when (C < 0)
if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
return getTrue(RetTy);
break;
case FCmpInst::FCMP_OEQ:
case FCmpInst::FCMP_OLE:
case FCmpInst::FCMP_OLT:
// (X >= 0) implies !(X < C) when (C < 0)
if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
return getFalse(RetTy);
break;
default:
break;
}
}
// Check comparison of [minnum/maxnum with constant] with other constant.
const APFloat *C2;
if ((match(LHS, m_Intrinsic<Intrinsic::minnum>(m_Value(), m_APFloat(C2))) &&
*C2 < *C) ||
(match(LHS, m_Intrinsic<Intrinsic::maxnum>(m_Value(), m_APFloat(C2))) &&
*C2 > *C)) {
bool IsMaxNum =
cast<IntrinsicInst>(LHS)->getIntrinsicID() == Intrinsic::maxnum;
// The ordered relationship and minnum/maxnum guarantee that we do not
// have NaN constants, so ordered/unordered preds are handled the same.
switch (Pred) {
case FCmpInst::FCMP_OEQ: case FCmpInst::FCMP_UEQ:
// minnum(X, LesserC) == C --> false
// maxnum(X, GreaterC) == C --> false
return getFalse(RetTy);
case FCmpInst::FCMP_ONE: case FCmpInst::FCMP_UNE:
// minnum(X, LesserC) != C --> true
// maxnum(X, GreaterC) != C --> true
return getTrue(RetTy);
case FCmpInst::FCMP_OGE: case FCmpInst::FCMP_UGE:
case FCmpInst::FCMP_OGT: case FCmpInst::FCMP_UGT:
// minnum(X, LesserC) >= C --> false
// minnum(X, LesserC) > C --> false
// maxnum(X, GreaterC) >= C --> true
// maxnum(X, GreaterC) > C --> true
return ConstantInt::get(RetTy, IsMaxNum);
case FCmpInst::FCMP_OLE: case FCmpInst::FCMP_ULE:
case FCmpInst::FCMP_OLT: case FCmpInst::FCMP_ULT:
// minnum(X, LesserC) <= C --> true
// minnum(X, LesserC) < C --> true
// maxnum(X, GreaterC) <= C --> false
// maxnum(X, GreaterC) < C --> false
return ConstantInt::get(RetTy, !IsMaxNum);
default:
// TRUE/FALSE/ORD/UNO should be handled before this.
llvm_unreachable("Unexpected fcmp predicate");
}
}
}
if (match(RHS, m_AnyZeroFP())) {
switch (Pred) {
case FCmpInst::FCMP_OGE:
case FCmpInst::FCMP_ULT:
// Positive or zero X >= 0.0 --> true
// Positive or zero X < 0.0 --> false
if ((FMF.noNaNs() || isKnownNeverNaN(LHS, Q.TLI)) &&
CannotBeOrderedLessThanZero(LHS, Q.TLI))
return Pred == FCmpInst::FCMP_OGE ? getTrue(RetTy) : getFalse(RetTy);
break;
case FCmpInst::FCMP_UGE:
case FCmpInst::FCMP_OLT:
// Positive or zero or nan X >= 0.0 --> true
// Positive or zero or nan X < 0.0 --> false
if (CannotBeOrderedLessThanZero(LHS, Q.TLI))
return Pred == FCmpInst::FCMP_UGE ? getTrue(RetTy) : getFalse(RetTy);
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 SimplifyQuery &Q) {
return ::SimplifyFCmpInst(Predicate, LHS, RHS, FMF, Q, RecursionLimit);
}
static Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
const SimplifyQuery &Q,
bool AllowRefinement,
unsigned MaxRecurse) {
// Trivial replacement.
if (V == Op)
return RepOp;
// We cannot replace a constant, and shouldn't even try.
if (isa<Constant>(Op))
return nullptr;
auto *I = dyn_cast<Instruction>(V);
if (!I || !is_contained(I->operands(), Op))
return nullptr;
// Replace Op with RepOp in instruction operands.
SmallVector<Value *, 8> NewOps(I->getNumOperands());
transform(I->operands(), NewOps.begin(),
[&](Value *V) { return V == Op ? RepOp : V; });
// 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 (which will
// be done in InstCombine).
// TODO: This is unsound, because it only catches some forms of refinement.
if (!AllowRefinement && canCreatePoison(cast<Operator>(I)))
return nullptr;
if (MaxRecurse) {
// The simplification queries below may return the original value. Consider:
// %div = udiv i32 %arg, %arg2
// %mul = mul nsw i32 %div, %arg2
// %cmp = icmp eq i32 %mul, %arg
// %sel = select i1 %cmp, i32 %div, i32 undef
// Replacing %arg by %mul, %div becomes "udiv i32 %mul, %arg2", which
// simplifies back to %arg. This can only happen because %mul does not
// dominate %div. To ensure a consistent return value contract, we make sure
// that this case returns nullptr as well.
auto PreventSelfSimplify = [V](Value *Simplified) {
return Simplified != V ? Simplified : nullptr;
};
if (auto *B = dyn_cast<BinaryOperator>(I))
return PreventSelfSimplify(SimplifyBinOp(B->getOpcode(), NewOps[0],
NewOps[1], Q, MaxRecurse - 1));
if (CmpInst *C = dyn_cast<CmpInst>(I))
return PreventSelfSimplify(SimplifyCmpInst(C->getPredicate(), NewOps[0],
NewOps[1], Q, MaxRecurse - 1));
if (auto *GEP = dyn_cast<GetElementPtrInst>(I))
return PreventSelfSimplify(SimplifyGEPInst(GEP->getSourceElementType(),
NewOps, 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.
SmallVector<Constant *, 8> ConstOps;
for (Value *NewOp : NewOps) {
if (Constant *ConstOp = dyn_cast<Constant>(NewOp))
ConstOps.push_back(ConstOp);
else
return nullptr;
}
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);
}
Value *llvm::SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
const SimplifyQuery &Q,
bool AllowRefinement) {
return ::SimplifyWithOpReplaced(V, Op, RepOp, Q, AllowRefinement,
RecursionLimit);
}
/// Try to simplify a select instruction when its condition operand is an
/// integer comparison where one operand of the compare is a constant.
static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X,
const APInt *Y, bool TrueWhenUnset) {
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;
}
return nullptr;
}
/// An alternative way to test if a bit is set or not uses sgt/slt instead of
/// eq/ne.
static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS,
ICmpInst::Predicate Pred,
Value *TrueVal, Value *FalseVal) {
Value *X;
APInt Mask;
if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask))
return nullptr;
return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask,
Pred == ICmpInst::ICMP_EQ);
}
/// Try to simplify a select instruction when its condition operand is an
/// integer comparison.
static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
Value *FalseVal, const SimplifyQuery &Q,
unsigned MaxRecurse) {
ICmpInst::Predicate Pred;
Value *CmpLHS, *CmpRHS;
if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
return nullptr;
// Canonicalize ne to eq predicate.
if (Pred == ICmpInst::ICMP_NE) {
Pred = ICmpInst::ICMP_EQ;
std::swap(TrueVal, FalseVal);
}
if (Pred == ICmpInst::ICMP_EQ && match(CmpRHS, m_Zero())) {
Value *X;
const APInt *Y;
if (match(CmpLHS, m_And(m_Value(X), m_APInt(Y))))
if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y,
/*TrueWhenUnset=*/true))
return V;
// Test for a bogus zero-shift-guard-op around funnel-shift or rotate.
Value *ShAmt;
auto isFsh = m_CombineOr(m_FShl(m_Value(X), m_Value(), m_Value(ShAmt)),
m_FShr(m_Value(), m_Value(X), m_Value(ShAmt)));
// (ShAmt == 0) ? fshl(X, *, ShAmt) : X --> X
// (ShAmt == 0) ? fshr(*, X, ShAmt) : X --> X
if (match(TrueVal, isFsh) && FalseVal == X && CmpLHS == ShAmt)
return X;
// Test for a zero-shift-guard-op around rotates. These are used to
// avoid UB from oversized shifts in raw IR rotate patterns, but the
// intrinsics do not have that problem.
// We do not allow this transform for the general funnel shift case because
// that would not preserve the poison safety of the original code.
auto isRotate =
m_CombineOr(m_FShl(m_Value(X), m_Deferred(X), m_Value(ShAmt)),
m_FShr(m_Value(X), m_Deferred(X), m_Value(ShAmt)));
// (ShAmt == 0) ? X : fshl(X, X, ShAmt) --> fshl(X, X, ShAmt)
// (ShAmt == 0) ? X : fshr(X, X, ShAmt) --> fshr(X, X, ShAmt)
if (match(FalseVal, isRotate) && TrueVal == X && CmpLHS == ShAmt &&
Pred == ICmpInst::ICMP_EQ)
return FalseVal;
// X == 0 ? abs(X) : -abs(X) --> -abs(X)
// X == 0 ? -abs(X) : abs(X) --> abs(X)
if (match(TrueVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))) &&
match(FalseVal, m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))))
return FalseVal;
if (match(TrueVal,
m_Neg(m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS)))) &&
match(FalseVal, m_Intrinsic<Intrinsic::abs>(m_Specific(CmpLHS))))
return FalseVal;
}
// Check for other compares that behave like bit test.
if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred,
TrueVal, FalseVal))
return V;
// 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,
/* AllowRefinement */ false, MaxRecurse) ==
TrueVal ||
SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q,
/* AllowRefinement */ false, MaxRecurse) ==
TrueVal)
return FalseVal;
if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q,
/* AllowRefinement */ true, MaxRecurse) ==
FalseVal ||
SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q,
/* AllowRefinement */ true, MaxRecurse) ==
FalseVal)
return FalseVal;
}
return nullptr;
}
/// Try to simplify a select instruction when its condition operand is a
/// floating-point comparison.
static Value *simplifySelectWithFCmp(Value *Cond, Value *T, Value *F,
const SimplifyQuery &Q) {
FCmpInst::Predicate Pred;
if (!match(Cond, m_FCmp(Pred, m_Specific(T), m_Specific(F))) &&
!match(Cond, m_FCmp(Pred, m_Specific(F), m_Specific(T))))
return nullptr;
// This transform is safe if we do not have (do not care about) -0.0 or if
// at least one operand is known to not be -0.0. Otherwise, the select can
// change the sign of a zero operand.
bool HasNoSignedZeros = Q.CxtI && isa<FPMathOperator>(Q.CxtI) &&
Q.CxtI->hasNoSignedZeros();
const APFloat *C;
if (HasNoSignedZeros || (match(T, m_APFloat(C)) && C->isNonZero()) ||
(match(F, m_APFloat(C)) && C->isNonZero())) {
// (T == F) ? T : F --> F
// (F == T) ? T : F --> F
if (Pred == FCmpInst::FCMP_OEQ)
return F;
// (T != F) ? T : F --> T
// (F != T) ? T : F --> T
if (Pred == FCmpInst::FCMP_UNE)
return T;
}
return nullptr;
}
/// Given operands for a SelectInst, see if we can fold the result.
/// If not, this returns null.
static Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
const SimplifyQuery &Q, unsigned MaxRecurse) {
if (auto *CondC = dyn_cast<Constant>(Cond)) {
if (auto *TrueC = dyn_cast<Constant>(TrueVal))
if (auto *FalseC = dyn_cast<Constant>(FalseVal))
return ConstantFoldSelectInstruction(CondC, TrueC, FalseC);
// select undef, X, Y -> X or Y
if (Q.isUndefValue(CondC))
return isa<Constant>(FalseVal) ? FalseVal : TrueVal;
// TODO: Vector constants with undef elements don't simplify.
// select true, X, Y -> X
if (CondC->isAllOnesValue())
return TrueVal;
// select false, X, Y -> Y
if (CondC->isNullValue())
return FalseVal;
}
// select i1 Cond, i1 true, i1 false --> i1 Cond
assert(Cond->getType()->isIntOrIntVectorTy(1) &&
"Select must have bool or bool vector condition");
assert(TrueVal->getType() == FalseVal->getType() &&
"Select must have same types for true/false ops");
if (Cond->getType() == TrueVal->getType() &&
match(TrueVal, m_One()) && match(FalseVal, m_ZeroInt()))
return Cond;
// select ?, X, X -> X
if (TrueVal == FalseVal)
return TrueVal;
// If the true or false value is undef, we can fold to the other value as
// long as the other value isn't poison.
// select ?, undef, X -> X
if (Q.isUndefValue(TrueVal) &&
isGuaranteedNotToBeUndefOrPoison(FalseVal, Q.AC, Q.CxtI, Q.DT))
return FalseVal;
// select ?, X, undef -> X
if (Q.isUndefValue(FalseVal) &&
isGuaranteedNotToBeUndefOrPoison(TrueVal, Q.AC, Q.CxtI, Q.DT))
return TrueVal;
// Deal with partial undef vector constants: select ?, VecC, VecC' --> VecC''
Constant *TrueC, *FalseC;
if (isa<FixedVectorType>(TrueVal->getType()) &&
match(TrueVal, m_Constant(TrueC)) &&
match(FalseVal, m_Constant(FalseC))) {
unsigned NumElts =
cast<FixedVectorType>(TrueC->getType())->getNumElements();
SmallVector<Constant *, 16> NewC;
for (unsigned i = 0; i != NumElts; ++i) {
// Bail out on incomplete vector constants.
Constant *TEltC = TrueC->getAggregateElement(i);
Constant *FEltC = FalseC->getAggregateElement(i);
if (!TEltC || !FEltC)
break;
// If the elements match (undef or not), that value is the result. If only
// one element is undef, choose the defined element as the safe result.
if (TEltC == FEltC)
NewC.push_back(TEltC);
else if (Q.isUndefValue(TEltC) &&
isGuaranteedNotToBeUndefOrPoison(FEltC))
NewC.push_back(FEltC);
else if (Q.isUndefValue(FEltC) &&
isGuaranteedNotToBeUndefOrPoison(TEltC))
NewC.push_back(TEltC);
else
break;
}
if (NewC.size() == NumElts)
return ConstantVector::get(NewC);
}
if (Value *V =
simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse))
return V;
if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal, Q))
return V;
if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal))
return V;
Optional<bool> Imp = isImpliedByDomCondition(Cond, Q.CxtI, Q.DL);
if (Imp)
return *Imp ? TrueVal : FalseVal;
return nullptr;
}
Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
const SimplifyQuery &Q) {
return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Q, 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 SimplifyQuery &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->getElementCount());
else if (VectorType *VT = dyn_cast<VectorType>(Ops[1]->getType()))
GEPTy = VectorType::get(GEPTy, VT->getElementCount());
// getelementptr poison, idx -> poison
// getelementptr baseptr, poison -> poison
if (any_of(Ops, [](const auto *V) { return isa<PoisonValue>(V); }))
return PoisonValue::get(GEPTy);
if (Q.isUndefValue(Ops[0]))
return UndefValue::get(GEPTy);
bool IsScalableVec = isa<ScalableVectorType>(SrcTy);
if (Ops.size() == 2) {
// getelementptr P, 0 -> P.
if (match(Ops[1], m_Zero()) && Ops[0]->getType() == GEPTy)
return Ops[0];
Type *Ty = SrcTy;
if (!IsScalableVec && 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 && Ops[0]->getType() == GEPTy)
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 CanSimplify = [GEPTy, &P, V = Ops[0]]() -> bool {
return P->getType() == GEPTy &&
getUnderlyingObject(P) == getUnderlyingObject(V);
};
// getelementptr V, (sub P, V) -> P if P points to a type of size 1.
if (TyAllocSize == 1 &&
match(Ops[1], m_Sub(m_PtrToInt(m_Value(P)),
m_PtrToInt(m_Specific(Ops[0])))) &&
CanSimplify())
return P;
// getelementptr V, (ashr (sub P, V), C) -> P if P points to a type of
// size 1 << C.
if (match(Ops[1], m_AShr(m_Sub(m_PtrToInt(m_Value(P)),
m_PtrToInt(m_Specific(Ops[0]))),
m_ConstantInt(C))) &&
TyAllocSize == 1ULL << C && CanSimplify())
return P;
// getelementptr V, (sdiv (sub P, V), C) -> P if P points to a type of
// size C.
if (match(Ops[1], m_SDiv(m_Sub(m_PtrToInt(m_Value(P)),
m_PtrToInt(m_Specific(Ops[0]))),
m_SpecificInt(TyAllocSize))) &&
CanSimplify())
return P;
}
}
}
if (!IsScalableVec && Q.DL.getTypeAllocSize(LastType) == 1 &&
all_of(Ops.slice(1).drop_back(1),
[](Value *Idx) { return match(Idx, m_Zero()); })) {
unsigned IdxWidth =
Q.DL.getIndexSizeInBits(Ops[0]->getType()->getPointerAddressSpace());
if (Q.DL.getTypeSizeInBits(Ops.back()->getType()) == IdxWidth) {
APInt BasePtrOffset(IdxWidth, 0);
Value *StrippedBasePtr =
Ops[0]->stripAndAccumulateInBoundsConstantOffsets(Q.DL,
BasePtrOffset);
// Avoid creating inttoptr of zero here: While LLVMs treatment of
// inttoptr is generally conservative, this particular case is folded to
// a null pointer, which will have incorrect provenance.
// gep (gep V, C), (sub 0, V) -> C
if (match(Ops.back(),
m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr)))) &&
!BasePtrOffset.isNullValue()) {
auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset);
return ConstantExpr::getIntToPtr(CI, GEPTy);
}
// gep (gep V, C), (xor V, -1) -> C-1
if (match(Ops.back(),
m_Xor(m_PtrToInt(m_Specific(StrippedBasePtr)), m_AllOnes())) &&
!BasePtrOffset.isOneValue()) {
auto *CI = ConstantInt::get(GEPTy->getContext(), BasePtrOffset - 1);
return ConstantExpr::getIntToPtr(CI, GEPTy);
}
}
}
// Check to see if this is constant foldable.
if (!all_of(Ops, [](Value *V) { return isa<Constant>(V); }))
return nullptr;
auto *CE = ConstantExpr::getGetElementPtr(SrcTy, cast<Constant>(Ops[0]),
Ops.slice(1));
return ConstantFoldConstant(CE, Q.DL);
}
Value *llvm::SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
const SimplifyQuery &Q) {
return ::SimplifyGEPInst(SrcTy, Ops, Q, 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 SimplifyQuery &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 (Q.isUndefValue(Val))
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 (Q.isUndefValue(Agg))
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 SimplifyQuery &Q) {
return ::SimplifyInsertValueInst(Agg, Val, Idxs, Q, RecursionLimit);
}
Value *llvm::SimplifyInsertElementInst(Value *Vec, Value *Val, Value *Idx,
const SimplifyQuery &Q) {
// Try to constant fold.
auto *VecC = dyn_cast<Constant>(Vec);
auto *ValC = dyn_cast<Constant>(Val);
auto *IdxC = dyn_cast<Constant>(Idx);
if (VecC && ValC && IdxC)
return ConstantExpr::getInsertElement(VecC, ValC, IdxC);
// For fixed-length vector, fold into poison if index is out of bounds.
if (auto *CI = dyn_cast<ConstantInt>(Idx)) {
if (isa<FixedVectorType>(Vec->getType()) &&
CI->uge(cast<FixedVectorType>(Vec->getType())->getNumElements()))
return PoisonValue::get(Vec->getType());
}
// If index is undef, it might be out of bounds (see above case)
if (Q.isUndefValue(Idx))
return PoisonValue::get(Vec->getType());
// If the scalar is poison, or it is undef and there is no risk of
// propagating poison from the vector value, simplify to the vector value.
if (isa<PoisonValue>(Val) ||
(Q.isUndefValue(Val) && isGuaranteedNotToBePoison(Vec)))
return Vec;
// If we are extracting a value from a vector, then inserting it into the same
// place, that's the input vector:
// insertelt Vec, (extractelt Vec, Idx), Idx --> Vec
if (match(Val, m_ExtractElt(m_Specific(Vec), m_Specific(Idx))))
return Vec;
return nullptr;
}
/// 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 SimplifyQuery &, 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 SimplifyQuery &Q) {
return ::SimplifyExtractValueInst(Agg, Idxs, Q, 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 SimplifyQuery &Q, unsigned) {
auto *VecVTy = cast<VectorType>(Vec->getType());
if (auto *CVec = dyn_cast<Constant>(Vec)) {
if (auto *CIdx = dyn_cast<Constant>(Idx))
return ConstantExpr::getExtractElement(CVec, CIdx);
// The index is not relevant if our vector is a splat.
if (auto *Splat = CVec->getSplatValue())
return Splat;
if (Q.isUndefValue(Vec))
return UndefValue::get(VecVTy->getElementType());
}
// 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)) {
// For fixed-length vector, fold into undef if index is out of bounds.
if (isa<FixedVectorType>(VecVTy) &&
IdxC->getValue().uge(cast<FixedVectorType>(VecVTy)->getNumElements()))
return PoisonValue::get(VecVTy->getElementType());
if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue()))
return Elt;
}
// An undef extract index can be arbitrarily chosen to be an out-of-range
// index value, which would result in the instruction being poison.
if (Q.isUndefValue(Idx))
return PoisonValue::get(VecVTy->getElementType());
return nullptr;
}
Value *llvm::SimplifyExtractElementInst(Value *Vec, Value *Idx,
const SimplifyQuery &Q) {
return ::SimplifyExtractElementInst(Vec, Idx, Q, RecursionLimit);
}
/// See if we can fold the given phi. If not, returns null.
static Value *SimplifyPHINode(PHINode *PN, const SimplifyQuery &Q) {
// WARNING: no matter how worthwhile it may seem, we can not perform PHI CSE
// here, because the PHI we may succeed simplifying to was not
// def-reachable from the original PHI!
// 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 (Q.isUndefValue(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 *SimplifyCastInst(unsigned CastOpc, Value *Op,
Type *Ty, const SimplifyQuery &Q, unsigned MaxRecurse) {
if (auto *C = dyn_cast<Constant>(Op))
return ConstantFoldCastOperand(CastOpc, C, Ty, Q.DL);
if (auto *CI = dyn_cast<CastInst>(Op)) {
auto *Src = CI->getOperand(0);
Type *SrcTy = Src->getType();
Type *MidTy = CI->getType();
Type *DstTy = Ty;
if (Src->getType() == Ty) {
auto FirstOp = static_cast<Instruction::CastOps>(CI->getOpcode());
auto SecondOp = static_cast<Instruction::CastOps>(CastOpc);
Type *SrcIntPtrTy =
SrcTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(SrcTy) : nullptr;
Type *MidIntPtrTy =
MidTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(MidTy) : nullptr;
Type *DstIntPtrTy =
DstTy->isPtrOrPtrVectorTy() ? Q.DL.getIntPtrType(DstTy) : nullptr;
if (CastInst::isEliminableCastPair(FirstOp, SecondOp, SrcTy, MidTy, DstTy,
SrcIntPtrTy, MidIntPtrTy,
DstIntPtrTy) == Instruction::BitCast)
return Src;
}
}
// bitcast x -> x
if (CastOpc == Instruction::BitCast)
if (Op->getType() == Ty)
return Op;
return nullptr;
}
Value *llvm::SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
const SimplifyQuery &Q) {
return ::SimplifyCastInst(CastOpc, Op, Ty, Q, RecursionLimit);
}
/// For the given destination element of a shuffle, peek through shuffles to
/// match a root vector source operand that contains that element in the same
/// vector lane (ie, the same mask index), so we can eliminate the shuffle(s).
static Value *foldIdentityShuffles(int DestElt, Value *Op0, Value *Op1,
int MaskVal, Value *RootVec,
unsigned MaxRecurse) {
if (!MaxRecurse--)
return nullptr;
// Bail out if any mask value is undefined. That kind of shuffle may be
// simplified further based on demanded bits or other folds.
if (MaskVal == -1)
return nullptr;
// The mask value chooses which source operand we need to look at next.
int InVecNumElts = cast<FixedVectorType>(Op0->getType())->getNumElements();
int RootElt = MaskVal;
Value *SourceOp = Op0;
if (MaskVal >= InVecNumElts) {
RootElt = MaskVal - InVecNumElts;
SourceOp = Op1;
}
// If the source operand is a shuffle itself, look through it to find the
// matching root vector.
if (auto *SourceShuf = dyn_cast<ShuffleVectorInst>(SourceOp)) {
return foldIdentityShuffles(
DestElt, SourceShuf->getOperand(0), SourceShuf->getOperand(1),
SourceShuf->getMaskValue(RootElt), RootVec, MaxRecurse);
}
// TODO: Look through bitcasts? What if the bitcast changes the vector element
// size?
// The source operand is not a shuffle. Initialize the root vector value for
// this shuffle if that has not been done yet.
if (!RootVec)
RootVec = SourceOp;
// Give up as soon as a source operand does not match the existing root value.
if (RootVec != SourceOp)
return nullptr;
// The element must be coming from the same lane in the source vector
// (although it may have crossed lanes in intermediate shuffles).
if (RootElt != DestElt)
return nullptr;
return RootVec;
}
static Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1,
ArrayRef<int> Mask, Type *RetTy,
const SimplifyQuery &Q,
unsigned MaxRecurse) {
if (all_of(Mask, [](int Elem) { return Elem == UndefMaskElem; }))
return UndefValue::get(RetTy);
auto *InVecTy = cast<VectorType>(Op0->getType());
unsigned MaskNumElts = Mask.size();
ElementCount InVecEltCount = InVecTy->getElementCount();
bool Scalable = InVecEltCount.isScalable();
SmallVector<int, 32> Indices;
Indices.assign(Mask.begin(), Mask.end());
// Canonicalization: If mask does not select elements from an input vector,
// replace that input vector with poison.
if (!Scalable) {
bool MaskSelects0 = false, MaskSelects1 = false;
unsigned InVecNumElts = InVecEltCount.getKnownMinValue();
for (unsigned i = 0; i != MaskNumElts; ++i) {
if (Indices[i] == -1)
continue;
if ((unsigned)Indices[i] < InVecNumElts)
MaskSelects0 = true;
else
MaskSelects1 = true;
}
if (!MaskSelects0)
Op0 = PoisonValue::get(InVecTy);
if (!MaskSelects1)
Op1 = PoisonValue::get(InVecTy);
}
auto *Op0Const = dyn_cast<Constant>(Op0);
auto *Op1Const = dyn_cast<Constant>(Op1);
// If all operands are constant, constant fold the shuffle. This
// transformation depends on the value of the mask which is not known at
// compile time for scalable vectors
if (Op0Const && Op1Const)
return ConstantExpr::getShuffleVector(Op0Const, Op1Const, Mask);
// Canonicalization: if only one input vector is constant, it shall be the
// second one. This transformation depends on the value of the mask which
// is not known at compile time for scalable vectors
if (!Scalable && Op0Const && !Op1Const) {
std::swap(Op0, Op1);
ShuffleVectorInst::commuteShuffleMask(Indices,
InVecEltCount.getKnownMinValue());
}
// A splat of an inserted scalar constant becomes a vector constant:
// shuf (inselt ?, C, IndexC), undef, <IndexC, IndexC...> --> <C, C...>
// NOTE: We may have commuted above, so analyze the updated Indices, not the
// original mask constant.
// NOTE: This transformation depends on the value of the mask which is not
// known at compile time for scalable vectors
Constant *C;
ConstantInt *IndexC;
if (!Scalable && match(Op0, m_InsertElt(m_Value(), m_Constant(C),
m_ConstantInt(IndexC)))) {
// Match a splat shuffle mask of the insert index allowing undef elements.
int InsertIndex = IndexC->getZExtValue();
if (all_of(Indices, [InsertIndex](int MaskElt) {
return MaskElt == InsertIndex || MaskElt == -1;
})) {
assert(isa<UndefValue>(Op1) && "Expected undef operand 1 for splat");
// Shuffle mask undefs become undefined constant result elements.
SmallVector<Constant *, 16> VecC(MaskNumElts, C);
for (unsigned i = 0; i != MaskNumElts; ++i)
if (Indices[i] == -1)
VecC[i] = UndefValue::get(C->getType());
return ConstantVector::get(VecC);
}
}
// A shuffle of a splat is always the splat itself. Legal if the shuffle's
// value type is same as the input vectors' type.
if (auto *OpShuf = dyn_cast<ShuffleVectorInst>(Op0))
if (Q.isUndefValue(Op1) && RetTy == InVecTy &&
is_splat(OpShuf->getShuffleMask()))
return Op0;
// All remaining transformation depend on the value of the mask, which is
// not known at compile time for scalable vectors.
if (Scalable)
return nullptr;
// Don't fold a shuffle with undef mask elements. This may get folded in a
// better way using demanded bits or other analysis.
// TODO: Should we allow this?
if (is_contained(Indices, -1))
return nullptr;
// Check if every element of this shuffle can be mapped back to the
// corresponding element of a single root vector. If so, we don't need this
// shuffle. This handles simple identity shuffles as well as chains of
// shuffles that may widen/narrow and/or move elements across lanes and back.
Value *RootVec = nullptr;
for (unsigned i = 0; i != MaskNumElts; ++i) {
// Note that recursion is limited for each vector element, so if any element
// exceeds the limit, this will fail to simplify.
RootVec =
foldIdentityShuffles(i, Op0, Op1, Indices[i], RootVec, MaxRecurse);
// We can't replace a widening/narrowing shuffle with one of its operands.
if (!RootVec || RootVec->getType() != RetTy)
return nullptr;
}
return RootVec;
}
/// Given operands for a ShuffleVectorInst, fold the result or return null.
Value *llvm::SimplifyShuffleVectorInst(Value *Op0, Value *Op1,
ArrayRef<int> Mask, Type *RetTy,
const SimplifyQuery &Q) {
return ::SimplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit);
}
static Constant *foldConstant(Instruction::UnaryOps Opcode,
Value *&Op, const SimplifyQuery &Q) {
if (auto *C = dyn_cast<Constant>(Op))
return ConstantFoldUnaryOpOperand(Opcode, C, Q.DL);
return nullptr;
}
/// Given the operand for an FNeg, see if we can fold the result. If not, this
/// returns null.
static Value *simplifyFNegInst(Value *Op, FastMathFlags FMF,
const SimplifyQuery &Q, unsigned MaxRecurse) {
if (Constant *C = foldConstant(Instruction::FNeg, Op, Q))
return C;
Value *X;
// fneg (fneg X) ==> X
if (match(Op, m_FNeg(m_Value(X))))
return X;
return nullptr;
}
Value *llvm::SimplifyFNegInst(Value *Op, FastMathFlags FMF,
const SimplifyQuery &Q) {
return ::simplifyFNegInst(Op, FMF, Q, RecursionLimit);
}
static Constant *propagateNaN(Constant *In) {
// If the input is a vector with undef elements, just return a default NaN.
if (!In->isNaN())
return ConstantFP::getNaN(In->getType());
// Propagate the existing NaN constant when possible.
// TODO: Should we quiet a signaling NaN?
return In;
}
/// Perform folds that are common to any floating-point operation. This implies
/// transforms based on undef/NaN because the operation itself makes no
/// difference to the result.
static Constant *simplifyFPOp(ArrayRef<Value *> Ops,
FastMathFlags FMF,
const SimplifyQuery &Q) {
for (Value *V : Ops) {
bool IsNan = match(V, m_NaN());
bool IsInf = match(V, m_Inf());
bool IsUndef = Q.isUndefValue(V);
// If this operation has 'nnan' or 'ninf' and at least 1 disallowed operand
// (an undef operand can be chosen to be Nan/Inf), then the result of
// this operation is poison.
if (FMF.noNaNs() && (IsNan || IsUndef))
return PoisonValue::get(V->getType());
if (FMF.noInfs() && (IsInf || IsUndef))
return PoisonValue::get(V->getType());
if (IsUndef || IsNan)
return propagateNaN(cast<Constant>(V));
}
return nullptr;
}
/// 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 SimplifyQuery &Q, unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q))
return C;
if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q))
return C;
// fadd X, -0 ==> X
if (match(Op1, m_NegZeroFP()))
return Op0;
// fadd X, 0 ==> X, when we know X is not -0
if (match(Op1, m_PosZeroFP()) &&
(FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
return Op0;
// With nnan: -X + X --> 0.0 (and commuted variant)
// We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN.
// Negative zeros are allowed because we always end up with positive zero:
// X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0
// X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0
// X = 0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0
// X = 0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0
if (FMF.noNaNs()) {
if (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) ||
match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0))))
return ConstantFP::getNullValue(Op0->getType());
if (match(Op0, m_FNeg(m_Specific(Op1))) ||
match(Op1, m_FNeg(m_Specific(Op0))))
return ConstantFP::getNullValue(Op0->getType());
}
// (X - Y) + Y --> X
// Y + (X - Y) --> X
Value *X;
if (FMF.noSignedZeros() && FMF.allowReassoc() &&
(match(Op0, m_FSub(m_Value(X), m_Specific(Op1))) ||
match(Op1, m_FSub(m_Value(X), m_Specific(Op0)))))
return X;
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 SimplifyQuery &Q, unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q))
return C;
if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q))
return C;
// fsub X, +0 ==> X
if (match(Op1, m_PosZeroFP()))
return Op0;
// fsub X, -0 ==> X, when we know X is not -0
if (match(Op1, m_NegZeroFP()) &&
(FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI)))
return Op0;
// fsub -0.0, (fsub -0.0, X) ==> X
// fsub -0.0, (fneg X) ==> X
Value *X;
if (match(Op0, m_NegZeroFP()) &&
match(Op1, m_FNeg(m_Value(X))))
return X;
// fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored.
// fsub 0.0, (fneg X) ==> X if signed zeros are ignored.
if (FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()) &&
(match(Op1, m_FSub(m_AnyZeroFP(), m_Value(X))) ||
match(Op1, m_FNeg(m_Value(X)))))
return X;
// fsub nnan x, x ==> 0.0
if (FMF.noNaNs() && Op0 == Op1)
return Constant::getNullValue(Op0->getType());
// Y - (Y - X) --> X
// (X + Y) - Y --> X
if (FMF.noSignedZeros() && FMF.allowReassoc() &&
(match(Op1, m_FSub(m_Specific(Op0), m_Value(X))) ||
match(Op0, m_c_FAdd(m_Specific(Op1), m_Value(X)))))
return X;
return nullptr;
}
static Value *SimplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q, unsigned MaxRecurse) {
if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q))
return C;
// fmul X, 1.0 ==> X
if (match(Op1, m_FPOne()))
return Op0;
// fmul 1.0, X ==> X
if (match(Op0, m_FPOne()))
return Op1;
// fmul nnan nsz X, 0 ==> 0
if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZeroFP()))
return ConstantFP::getNullValue(Op0->getType());
// fmul nnan nsz 0, X ==> 0
if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()))
return ConstantFP::getNullValue(Op1->getType());
// sqrt(X) * sqrt(X) --> X, if we can:
// 1. Remove the intermediate rounding (reassociate).
// 2. Ignore non-zero negative numbers because sqrt would produce NAN.
// 3. Ignore -0.0 because sqrt(-0.0) == -0.0, but -0.0 * -0.0 == 0.0.
Value *X;
if (Op0 == Op1 && match(Op0, m_Intrinsic<Intrinsic::sqrt>(m_Value(X))) &&
FMF.allowReassoc() && FMF.noNaNs() && FMF.noSignedZeros())
return X;
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 SimplifyQuery &Q, unsigned MaxRecurse) {
if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q))
return C;
// Now apply simplifications that do not require rounding.
return SimplifyFMAFMul(Op0, Op1, FMF, Q, MaxRecurse);
}
Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q) {
return ::SimplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit);
}
Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q) {
return ::SimplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit);
}
Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q) {
return ::SimplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit);
}
Value *llvm::SimplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q) {
return ::SimplifyFMAFMul(Op0, Op1, FMF, Q, RecursionLimit);
}
static Value *SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q, unsigned) {
if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q))
return C;
if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q))
return C;
// X / 1.0 -> X
if (match(Op1, m_FPOne()))
return Op0;
// 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_AnyZeroFP()))
return ConstantFP::getNullValue(Op0->getType());
if (FMF.noNaNs()) {
// X / X -> 1.0 is legal when NaNs are ignored.
// We can ignore infinities because INF/INF is NaN.
if (Op0 == Op1)
return ConstantFP::get(Op0->getType(), 1.0);
// (X * Y) / Y --> X if we can reassociate to the above form.
Value *X;
if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1))))
return X;
// -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 (match(Op0, m_FNegNSZ(m_Specific(Op1))) ||
match(Op1, m_FNegNSZ(m_Specific(Op0))))
return ConstantFP::get(Op0->getType(), -1.0);
}
return nullptr;
}
Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q) {
return ::SimplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit);
}
static Value *SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q, unsigned) {
if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q))
return C;
if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q))
return C;
// Unlike fdiv, the result of frem always matches the sign of the dividend.
// The constant match may include undef elements in a vector, so return a full
// zero constant as the result.
if (FMF.noNaNs()) {
// +0 % X -> 0
if (match(Op0, m_PosZeroFP()))
return ConstantFP::getNullValue(Op0->getType());
// -0 % X -> -0
if (match(Op0, m_NegZeroFP()))
return ConstantFP::getNegativeZero(Op0->getType());
}
return nullptr;
}
Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q) {
return ::SimplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit);
}
//=== Helper functions for higher up the class hierarchy.
/// Given the operand for a UnaryOperator, see if we can fold the result.
/// If not, this returns null.
static Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q,
unsigned MaxRecurse) {
switch (Opcode) {
case Instruction::FNeg:
return simplifyFNegInst(Op, FastMathFlags(), Q, MaxRecurse);
default:
llvm_unreachable("Unexpected opcode");
}
}
/// Given the operand for a UnaryOperator, see if we can fold the result.
/// If not, this returns null.
/// Try to use FastMathFlags when folding the result.
static Value *simplifyFPUnOp(unsigned Opcode, Value *Op,
const FastMathFlags &FMF,
const SimplifyQuery &Q, unsigned MaxRecurse) {
switch (Opcode) {
case Instruction::FNeg:
return simplifyFNegInst(Op, FMF, Q, MaxRecurse);
default:
return simplifyUnOp(Opcode, Op, Q, MaxRecurse);
}
}
Value *llvm::SimplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q) {
return ::simplifyUnOp(Opcode, Op, Q, RecursionLimit);
}
Value *llvm::SimplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF,
const SimplifyQuery &Q) {
return ::simplifyFPUnOp(Opcode, Op, FMF, Q, RecursionLimit);
}
/// 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 SimplifyQuery &Q, unsigned MaxRecurse) {
switch (Opcode) {
case Instruction::Add:
return SimplifyAddInst(LHS, RHS, false, false, Q, MaxRecurse);
case Instruction::Sub:
return SimplifySubInst(LHS, RHS, false, false, Q, MaxRecurse);
case Instruction::Mul:
return SimplifyMulInst(LHS, RHS, Q, MaxRecurse);
case Instruction::SDiv:
return SimplifySDivInst(LHS, RHS, Q, MaxRecurse);
case Instruction::UDiv:
return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse);
case Instruction::SRem:
return SimplifySRemInst(LHS, RHS, Q, MaxRecurse);
case Instruction::URem:
return SimplifyURemInst(LHS, RHS, Q, MaxRecurse);
case Instruction::Shl:
return SimplifyShlInst(LHS, RHS, false, false, Q, MaxRecurse);
case Instruction::LShr:
return SimplifyLShrInst(LHS, RHS, false, Q, MaxRecurse);
case Instruction::AShr:
return SimplifyAShrInst(LHS, RHS, 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);
case Instruction::FAdd:
return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
case Instruction::FSub:
return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
case Instruction::FMul:
return SimplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
case Instruction::FDiv:
return SimplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
case Instruction::FRem:
return SimplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse);
default:
llvm_unreachable("Unexpected opcode");
}
}
/// Given operands for a BinaryOperator, see if we can fold the result.
/// If not, this returns null.
/// Try to use FastMathFlags when folding the result.
static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const FastMathFlags &FMF, const SimplifyQuery &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);
case Instruction::FDiv:
return SimplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse);
default:
return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse);
}
}
Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
const SimplifyQuery &Q) {
return ::SimplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit);
}
Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
FastMathFlags FMF, const SimplifyQuery &Q) {
return ::SimplifyBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit);
}
/// Given operands for a CmpInst, see if we can fold the result.
static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const SimplifyQuery &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 SimplifyQuery &Q) {
return ::SimplifyCmpInst(Predicate, LHS, RHS, Q, 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:
case Intrinsic::roundeven:
case Intrinsic::canonicalize:
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);
}
static Value *simplifyUnaryIntrinsic(Function *F, Value *Op0,
const SimplifyQuery &Q) {
// Idempotent functions return the same result when called repeatedly.
Intrinsic::ID IID = F->getIntrinsicID();
if (IsIdempotent(IID))
if (auto *II = dyn_cast<IntrinsicInst>(Op0))
if (II->getIntrinsicID() == IID)
return II;
Value *X;
switch (IID) {
case Intrinsic::fabs:
if (SignBitMustBeZero(Op0, Q.TLI)) return Op0;
break;
case Intrinsic::bswap:
// bswap(bswap(x)) -> x
if (match(Op0, m_BSwap(m_Value(X)))) return X;
break;
case Intrinsic::bitreverse:
// bitreverse(bitreverse(x)) -> x
if (match(Op0, m_BitReverse(m_Value(X)))) return X;
break;
case Intrinsic::ctpop: {
// If everything but the lowest bit is zero, that bit is the pop-count. Ex:
// ctpop(and X, 1) --> and X, 1
unsigned BitWidth = Op0->getType()->getScalarSizeInBits();
if (MaskedValueIsZero(Op0, APInt::getHighBitsSet(BitWidth, BitWidth - 1),
Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return Op0;
break;
}
case Intrinsic::exp:
// exp(log(x)) -> x
if (Q.CxtI->hasAllowReassoc() &&
match(Op0, m_Intrinsic<Intrinsic::log>(m_Value(X)))) return X;
break;
case Intrinsic::exp2:
// exp2(log2(x)) -> x
if (Q.CxtI->hasAllowReassoc() &&
match(Op0, m_Intrinsic<Intrinsic::log2>(m_Value(X)))) return X;
break;
case Intrinsic::log:
// log(exp(x)) -> x
if (Q.CxtI->hasAllowReassoc() &&
match(Op0, m_Intrinsic<Intrinsic::exp>(m_Value(X)))) return X;
break;
case Intrinsic::log2:
// log2(exp2(x)) -> x
if (Q.CxtI->hasAllowReassoc() &&
(match(Op0, m_Intrinsic<Intrinsic::exp2>(m_Value(X))) ||
match(Op0, m_Intrinsic<Intrinsic::pow>(m_SpecificFP(2.0),
m_Value(X))))) return X;
break;
case Intrinsic::log10:
// log10(pow(10.0, x)) -> x
if (Q.CxtI->hasAllowReassoc() &&
match(Op0, m_Intrinsic<Intrinsic::pow>(m_SpecificFP(10.0),
m_Value(X)))) return X;
break;
case Intrinsic::floor:
case Intrinsic::trunc:
case Intrinsic::ceil:
case Intrinsic::round:
case Intrinsic::roundeven:
case Intrinsic::nearbyint:
case Intrinsic::rint: {
// floor (sitofp x) -> sitofp x
// floor (uitofp x) -> uitofp x
//
// Converting from int always results in a finite integral number or
// infinity. For either of those inputs, these rounding functions always
// return the same value, so the rounding can be eliminated.
if (match(Op0, m_SIToFP(m_Value())) || match(Op0, m_UIToFP(m_Value())))
return Op0;
break;
}
case Intrinsic::experimental_vector_reverse:
// experimental.vector.reverse(experimental.vector.reverse(x)) -> x
if (match(Op0,
m_Intrinsic<Intrinsic::experimental_vector_reverse>(m_Value(X))))
return X;
break;
default:
break;
}
return nullptr;
}
static APInt getMaxMinLimit(Intrinsic::ID IID, unsigned BitWidth) {
switch (IID) {
case Intrinsic::smax: return APInt::getSignedMaxValue(BitWidth);
case Intrinsic::smin: return APInt::getSignedMinValue(BitWidth);
case Intrinsic::umax: return APInt::getMaxValue(BitWidth);
case Intrinsic::umin: return APInt::getMinValue(BitWidth);
default: llvm_unreachable("Unexpected intrinsic");
}
}
static ICmpInst::Predicate getMaxMinPredicate(Intrinsic::ID IID) {
switch (IID) {
case Intrinsic::smax: return ICmpInst::ICMP_SGE;
case Intrinsic::smin: return ICmpInst::ICMP_SLE;
case Intrinsic::umax: return ICmpInst::ICMP_UGE;
case Intrinsic::umin: return ICmpInst::ICMP_ULE;
default: llvm_unreachable("Unexpected intrinsic");
}
}
/// Given a min/max intrinsic, see if it can be removed based on having an
/// operand that is another min/max intrinsic with shared operand(s). The caller
/// is expected to swap the operand arguments to handle commutation.
static Value *foldMinMaxSharedOp(Intrinsic::ID IID, Value *Op0, Value *Op1) {
Value *X, *Y;
if (!match(Op0, m_MaxOrMin(m_Value(X), m_Value(Y))))
return nullptr;
auto *MM0 = dyn_cast<IntrinsicInst>(Op0);
if (!MM0)
return nullptr;
Intrinsic::ID IID0 = MM0->getIntrinsicID();
if (Op1 == X || Op1 == Y ||
match(Op1, m_c_MaxOrMin(m_Specific(X), m_Specific(Y)))) {
// max (max X, Y), X --> max X, Y
if (IID0 == IID)
return MM0;
// max (min X, Y), X --> X
if (IID0 == getInverseMinMaxIntrinsic(IID))
return Op1;
}
return nullptr;
}
static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1,
const SimplifyQuery &Q) {
Intrinsic::ID IID = F->getIntrinsicID();
Type *ReturnType = F->getReturnType();
unsigned BitWidth = ReturnType->getScalarSizeInBits();
switch (IID) {
case Intrinsic::abs:
// abs(abs(x)) -> abs(x). We don't need to worry about the nsw arg here.
// It is always ok to pick the earlier abs. We'll just lose nsw if its only
// on the outer abs.
if (match(Op0, m_Intrinsic<Intrinsic::abs>(m_Value(), m_Value())))
return Op0;
break;
case Intrinsic::cttz: {
Value *X;
if (match(Op0, m_Shl(m_One(), m_Value(X))))
return X;
break;
}
case Intrinsic::ctlz: {
Value *X;
if (match(Op0, m_LShr(m_SignMask(), m_Value(X))))
return X;
break;
}
case Intrinsic::smax:
case Intrinsic::smin:
case Intrinsic::umax:
case Intrinsic::umin: {
// If the arguments are the same, this is a no-op.
if (Op0 == Op1)
return Op0;
// Canonicalize constant operand as Op1.
if (isa<Constant>(Op0))
std::swap(Op0, Op1);
// Assume undef is the limit value.
if (Q.isUndefValue(Op1))
return ConstantInt::get(ReturnType, getMaxMinLimit(IID, BitWidth));
const APInt *C;
if (match(Op1, m_APIntAllowUndef(C))) {
// Clamp to limit value. For example:
// umax(i8 %x, i8 255) --> 255
if (*C == getMaxMinLimit(IID, BitWidth))
return ConstantInt::get(ReturnType, *C);
// If the constant op is the opposite of the limit value, the other must
// be larger/smaller or equal. For example:
// umin(i8 %x, i8 255) --> %x
if (*C == getMaxMinLimit(getInverseMinMaxIntrinsic(IID), BitWidth))
return Op0;
// Remove nested call if constant operands allow it. Example:
// max (max X, 7), 5 -> max X, 7
auto *MinMax0 = dyn_cast<IntrinsicInst>(Op0);
if (MinMax0 && MinMax0->getIntrinsicID() == IID) {
// TODO: loosen undef/splat restrictions for vector constants.
Value *M00 = MinMax0->getOperand(0), *M01 = MinMax0->getOperand(1);
const APInt *InnerC;
if ((match(M00, m_APInt(InnerC)) || match(M01, m_APInt(InnerC))) &&
((IID == Intrinsic::smax && InnerC->sge(*C)) ||
(IID == Intrinsic::smin && InnerC->sle(*C)) ||
(IID == Intrinsic::umax && InnerC->uge(*C)) ||
(IID == Intrinsic::umin && InnerC->ule(*C))))
return Op0;
}
}
if (Value *V = foldMinMaxSharedOp(IID, Op0, Op1))
return V;
if (Value *V = foldMinMaxSharedOp(IID, Op1, Op0))
return V;
ICmpInst::Predicate Pred = getMaxMinPredicate(IID);
if (isICmpTrue(Pred, Op0, Op1, Q.getWithoutUndef(), RecursionLimit))
return Op0;
if (isICmpTrue(Pred, Op1, Op0, Q.getWithoutUndef(), RecursionLimit))
return Op1;
if (Optional<bool> Imp =
isImpliedByDomCondition(Pred, Op0, Op1, Q.CxtI, Q.DL))
return *Imp ? Op0 : Op1;
if (Optional<bool> Imp =
isImpliedByDomCondition(Pred, Op1, Op0, Q.CxtI, Q.DL))
return *Imp ? Op1 : Op0;
break;
}
case Intrinsic::usub_with_overflow:
case Intrinsic::ssub_with_overflow:
// X - X -> { 0, false }
// X - undef -> { 0, false }
// undef - X -> { 0, false }
if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1))
return Constant::getNullValue(ReturnType);
break;
case Intrinsic::uadd_with_overflow:
case Intrinsic::sadd_with_overflow:
// X + undef -> { -1, false }
// undef + x -> { -1, false }
if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1)) {
return ConstantStruct::get(
cast<StructType>(ReturnType),
{Constant::getAllOnesValue(ReturnType->getStructElementType(0)),
Constant::getNullValue(ReturnType->getStructElementType(1))});
}
break;
case Intrinsic::umul_with_overflow:
case Intrinsic::smul_with_overflow:
// 0 * X -> { 0, false }
// X * 0 -> { 0, false }
if (match(Op0, m_Zero()) || match(Op1, m_Zero()))
return Constant::getNullValue(ReturnType);
// undef * X -> { 0, false }
// X * undef -> { 0, false }
if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1))
return Constant::getNullValue(ReturnType);
break;
case Intrinsic::uadd_sat:
// sat(MAX + X) -> MAX
// sat(X + MAX) -> MAX
if (match(Op0, m_AllOnes()) || match(Op1, m_AllOnes()))
return Constant::getAllOnesValue(ReturnType);
LLVM_FALLTHROUGH;
case Intrinsic::sadd_sat:
// sat(X + undef) -> -1
// sat(undef + X) -> -1
// For unsigned: Assume undef is MAX, thus we saturate to MAX (-1).
// For signed: Assume undef is ~X, in which case X + ~X = -1.
if (Q.isUndefValue(Op0) || Q.isUndefValue(Op1))
return Constant::getAllOnesValue(ReturnType);
// X + 0 -> X
if (match(Op1, m_Zero()))
return Op0;
// 0 + X -> X
if (match(Op0, m_Zero()))
return Op1;
break;
case Intrinsic::usub_sat:
// sat(0 - X) -> 0, sat(X - MAX) -> 0
if (match(Op0, m_Zero()) || match(Op1, m_AllOnes()))
return Constant::getNullValue(ReturnType);
LLVM_FALLTHROUGH;
case Intrinsic::ssub_sat:
// X - X -> 0, X - undef -> 0, undef - X -> 0
if (Op0 == Op1 || Q.isUndefValue(Op0) || Q.isUndefValue(Op1))
return Constant::getNullValue(ReturnType);
// X - 0 -> X
if (match(Op1, m_Zero()))
return Op0;
break;
case Intrinsic::load_relative:
if (auto *C0 = dyn_cast<Constant>(Op0))
if (auto *C1 = dyn_cast<Constant>(Op1))
return SimplifyRelativeLoad(C0, C1, Q.DL);
break;
case Intrinsic::powi:
if (auto *Power = dyn_cast<ConstantInt>(Op1)) {
// powi(x, 0) -> 1.0
if (Power->isZero())
return ConstantFP::get(Op0->getType(), 1.0);
// powi(x, 1) -> x
if (Power->isOne())
return Op0;
}
break;
case Intrinsic::copysign:
// copysign X, X --> X
if (Op0 == Op1)
return Op0;
// copysign -X, X --> X
// copysign X, -X --> -X
if (match(Op0, m_FNeg(m_Specific(Op1))) ||
match(Op1, m_FNeg(m_Specific(Op0))))
return Op1;
break;
case Intrinsic::maxnum:
case Intrinsic::minnum:
case Intrinsic::maximum:
case Intrinsic::minimum: {
// If the arguments are the same, this is a no-op.
if (Op0 == Op1) return Op0;
// Canonicalize constant operand as Op1.
if (isa<Constant>(Op0))
std::swap(Op0, Op1);
// If an argument is undef, return the other argument.
if (Q.isUndefValue(Op1))
return Op0;
bool PropagateNaN = IID == Intrinsic::minimum || IID == Intrinsic::maximum;
bool IsMin = IID == Intrinsic::minimum || IID == Intrinsic::minnum;
// minnum(X, nan) -> X
// maxnum(X, nan) -> X
// minimum(X, nan) -> nan
// maximum(X, nan) -> nan
if (match(Op1, m_NaN()))
return PropagateNaN ? propagateNaN(cast<Constant>(Op1)) : Op0;
// In the following folds, inf can be replaced with the largest finite
// float, if the ninf flag is set.
const APFloat *C;
if (match(Op1, m_APFloat(C)) &&
(C->isInfinity() || (Q.CxtI->hasNoInfs() && C->isLargest()))) {
// minnum(X, -inf) -> -inf
// maxnum(X, +inf) -> +inf
// minimum(X, -inf) -> -inf if nnan
// maximum(X, +inf) -> +inf if nnan
if (C->isNegative() == IsMin && (!PropagateNaN || Q.CxtI->hasNoNaNs()))
return ConstantFP::get(ReturnType, *C);
// minnum(X, +inf) -> X if nnan
// maxnum(X, -inf) -> X if nnan
// minimum(X, +inf) -> X
// maximum(X, -inf) -> X
if (C->isNegative() != IsMin && (PropagateNaN || Q.CxtI->hasNoNaNs()))
return Op0;
}
// Min/max of the same operation with common operand:
// m(m(X, Y)), X --> m(X, Y) (4 commuted variants)
if (auto *M0 = dyn_cast<IntrinsicInst>(Op0))
if (M0->getIntrinsicID() == IID &&
(M0->getOperand(0) == Op1 || M0->getOperand(1) == Op1))
return Op0;
if (auto *M1 = dyn_cast<IntrinsicInst>(Op1))
if (M1->getIntrinsicID() == IID &&
(M1->getOperand(0) == Op0 || M1->getOperand(1) == Op0))
return Op1;
break;
}
default:
break;
}
return nullptr;
}
static Value *simplifyIntrinsic(CallBase *Call, const SimplifyQuery &Q) {
// Intrinsics with no operands have some kind of side effect. Don't simplify.
unsigned NumOperands = Call->getNumArgOperands();
if (!NumOperands)
return nullptr;
Function *F = cast<Function>(Call->getCalledFunction());
Intrinsic::ID IID = F->getIntrinsicID();
if (NumOperands == 1)
return simplifyUnaryIntrinsic(F, Call->getArgOperand(0), Q);
if (NumOperands == 2)
return simplifyBinaryIntrinsic(F, Call->getArgOperand(0),
Call->getArgOperand(1), Q);
// Handle intrinsics with 3 or more arguments.
switch (IID) {
case Intrinsic::masked_load:
case Intrinsic::masked_gather: {
Value *MaskArg = Call->getArgOperand(2);
Value *PassthruArg = Call->getArgOperand(3);
// If the mask is all zeros or undef, the "passthru" argument is the result.
if (maskIsAllZeroOrUndef(MaskArg))
return PassthruArg;
return nullptr;
}
case Intrinsic::fshl:
case Intrinsic::fshr: {
Value *Op0 = Call->getArgOperand(0), *Op1 = Call->getArgOperand(1),
*ShAmtArg = Call->getArgOperand(2);
// If both operands are undef, the result is undef.
if (Q.isUndefValue(Op0) && Q.isUndefValue(Op1))
return UndefValue::get(F->getReturnType());
// If shift amount is undef, assume it is zero.
if (Q.isUndefValue(ShAmtArg))
return Call->getArgOperand(IID == Intrinsic::fshl ? 0 : 1);
const APInt *ShAmtC;
if (match(ShAmtArg, m_APInt(ShAmtC))) {
// If there's effectively no shift, return the 1st arg or 2nd arg.
APInt BitWidth = APInt(ShAmtC->getBitWidth(), ShAmtC->getBitWidth());
if (ShAmtC->urem(BitWidth).isNullValue())
return Call->getArgOperand(IID == Intrinsic::fshl ? 0 : 1);
}
return nullptr;
}
case Intrinsic::fma:
case Intrinsic::fmuladd: {
Value *Op0 = Call->getArgOperand(0);
Value *Op1 = Call->getArgOperand(1);
Value *Op2 = Call->getArgOperand(2);
if (Value *V = simplifyFPOp({ Op0, Op1, Op2 }, {}, Q))
return V;
return nullptr;
}
case Intrinsic::smul_fix:
case Intrinsic::smul_fix_sat: {
Value *Op0 = Call->getArgOperand(0);
Value *Op1 = Call->getArgOperand(1);
Value *Op2 = Call->getArgOperand(2);
Type *ReturnType = F->getReturnType();
// Canonicalize constant operand as Op1 (ConstantFolding handles the case
// when both Op0 and Op1 are constant so we do not care about that special
// case here).
if (isa<Constant>(Op0))
std::swap(Op0, Op1);
// X * 0 -> 0
if (match(Op1, m_Zero()))
return Constant::getNullValue(ReturnType);
// X * undef -> 0
if (Q.isUndefValue(Op1))
return Constant::getNullValue(ReturnType);
// X * (1 << Scale) -> X
APInt ScaledOne =
APInt::getOneBitSet(ReturnType->getScalarSizeInBits(),
cast<ConstantInt>(Op2)->getZExtValue());
if (ScaledOne.isNonNegative() && match(Op1, m_SpecificInt(ScaledOne)))
return Op0;
return nullptr;
}
default:
return nullptr;
}
}
static Value *tryConstantFoldCall(CallBase *Call, const SimplifyQuery &Q) {
auto *F = dyn_cast<Function>(Call->getCalledOperand());
if (!F || !canConstantFoldCallTo(Call, F))
return nullptr;
SmallVector<Constant *, 4> ConstantArgs;
unsigned NumArgs = Call->getNumArgOperands();
ConstantArgs.reserve(NumArgs);
for (auto &Arg : Call->args()) {
Constant *C = dyn_cast<Constant>(&Arg);
if (!C) {
if (isa<MetadataAsValue>(Arg.get()))
continue;
return nullptr;
}
ConstantArgs.push_back(C);
}
return ConstantFoldCall(Call, F, ConstantArgs, Q.TLI);
}
Value *llvm::SimplifyCall(CallBase *Call, const SimplifyQuery &Q) {
// musttail calls can only be simplified if they are also DCEd.
// As we can't guarantee this here, don't simplify them.
if (Call->isMustTailCall())
return nullptr;
// call undef -> poison
// call null -> poison
Value *Callee = Call->getCalledOperand();
if (isa<UndefValue>(Callee) || isa<ConstantPointerNull>(Callee))
return PoisonValue::get(Call->getType());
if (Value *V = tryConstantFoldCall(Call, Q))
return V;
auto *F = dyn_cast<Function>(Callee);
if (F && F->isIntrinsic())
if (Value *Ret = simplifyIntrinsic(Call, Q))
return Ret;
return nullptr;
}
/// Given operands for a Freeze, see if we can fold the result.
static Value *SimplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) {
// Use a utility function defined in ValueTracking.
if (llvm::isGuaranteedNotToBeUndefOrPoison(Op0, Q.AC, Q.CxtI, Q.DT))
return Op0;
// We have room for improvement.
return nullptr;
}
Value *llvm::SimplifyFreezeInst(Value *Op0, const SimplifyQuery &Q) {
return ::SimplifyFreezeInst(Op0, Q);
}
/// See if we can compute a simplified version of this instruction.
/// If not, this returns null.
Value *llvm::SimplifyInstruction(Instruction *I, const SimplifyQuery &SQ,
OptimizationRemarkEmitter *ORE) {
const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I);
Value *Result;
switch (I->getOpcode()) {
default:
Result = ConstantFoldInstruction(I, Q.DL, Q.TLI);
break;
case Instruction::FNeg:
Result = SimplifyFNegInst(I->getOperand(0), I->getFastMathFlags(), Q);
break;
case Instruction::FAdd:
Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), Q);
break;
case Instruction::Add:
Result =
SimplifyAddInst(I->getOperand(0), I->getOperand(1),
Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)),
Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q);
break;
case Instruction::FSub:
Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), Q);
break;
case Instruction::Sub:
Result =
SimplifySubInst(I->getOperand(0), I->getOperand(1),
Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)),
Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q);
break;
case Instruction::FMul:
Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), Q);
break;
case Instruction::Mul:
Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), Q);
break;
case Instruction::SDiv:
Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), Q);
break;
case Instruction::UDiv:
Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), Q);
break;
case Instruction::FDiv:
Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), Q);
break;
case Instruction::SRem:
Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), Q);
break;
case Instruction::URem:
Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), Q);
break;
case Instruction::FRem:
Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1),
I->getFastMathFlags(), Q);
break;
case Instruction::Shl:
Result =
SimplifyShlInst(I->getOperand(0), I->getOperand(1),
Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)),
Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q);
break;
case Instruction::LShr:
Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
Q.IIQ.isExact(cast<BinaryOperator>(I)), Q);
break;
case Instruction::AShr:
Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
Q.IIQ.isExact(cast<BinaryOperator>(I)), Q);
break;
case Instruction::And:
Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), Q);
break;
case Instruction::Or:
Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), Q);
break;
case Instruction::Xor:
Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), Q);
break;
case Instruction::ICmp:
Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), Q);
break;
case Instruction::FCmp:
Result =
SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), I->getOperand(0),
I->getOperand(1), I->getFastMathFlags(), Q);
break;
case Instruction::Select:
Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
I->getOperand(2), Q);
break;
case Instruction::GetElementPtr: {
SmallVector<Value *, 8> Ops(I->operands());
Result = SimplifyGEPInst(cast<GetElementPtrInst>(I)->getSourceElementType(),
Ops, Q);
break;
}
case Instruction::InsertValue: {
InsertValueInst *IV = cast<InsertValueInst>(I);
Result = SimplifyInsertValueInst(IV->getAggregateOperand(),
IV->getInsertedValueOperand(),
IV->getIndices(), Q);
break;
}
case Instruction::InsertElement: {
auto *IE = cast<InsertElementInst>(I);
Result = SimplifyInsertElementInst(IE->getOperand(0), IE->getOperand(1),
IE->getOperand(2), Q);
break;
}
case Instruction::ExtractValue: {
auto *EVI = cast<ExtractValueInst>(I);
Result = SimplifyExtractValueInst(EVI->getAggregateOperand(),
EVI->getIndices(), Q);
break;
}
case Instruction::ExtractElement: {
auto *EEI = cast<ExtractElementInst>(I);
Result = SimplifyExtractElementInst(EEI->getVectorOperand(),
EEI->getIndexOperand(), Q);
break;
}
case Instruction::ShuffleVector: {
auto *SVI = cast<ShuffleVectorInst>(I);
Result =
SimplifyShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1),
SVI->getShuffleMask(), SVI->getType(), Q);
break;
}
case Instruction::PHI:
Result = SimplifyPHINode(cast<PHINode>(I), Q);
break;
case Instruction::Call: {
Result = SimplifyCall(cast<CallInst>(I), Q);
break;
}
case Instruction::Freeze:
Result = SimplifyFreezeInst(I->getOperand(0), Q);
break;
#define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc:
#include "llvm/IR/Instruction.def"
#undef HANDLE_CAST_INST
Result =
SimplifyCastInst(I->getOpcode(), I->getOperand(0), I->getType(), Q);
break;
case Instruction::Alloca:
// No simplifications for Alloca and it can't be constant folded.
Result = nullptr;
break;
}
/// 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;
}
/// 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. Recursively visited users which could not be
/// simplified themselves are to the optional UnsimplifiedUsers set for
/// further processing by the caller.
///
/// 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,
SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr) {
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->isEHPad() && !I->isTerminator() &&
!I->mayHaveSideEffects())
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) {
if (UnsimplifiedUsers)
UnsimplifiedUsers->insert(I);
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->isEHPad() && !I->isTerminator() &&
!I->mayHaveSideEffects())
I->eraseFromParent();
}
return Simplified;
}
bool llvm::replaceAndRecursivelySimplify(
Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI,
const DominatorTree *DT, AssumptionCache *AC,
SmallSetVector<Instruction *, 8> *UnsimplifiedUsers) {
assert(I != SimpleV && "replaceAndRecursivelySimplify(X,X) is not valid!");
assert(SimpleV && "Must provide a simplified value.");
return replaceAndRecursivelySimplifyImpl(I, SimpleV, TLI, DT, AC,
UnsimplifiedUsers);
}
namespace llvm {
const SimplifyQuery getBestSimplifyQuery(Pass &P, Function &F) {
auto *DTWP = P.getAnalysisIfAvailable<DominatorTreeWrapperPass>();
auto *DT = DTWP ? &DTWP->getDomTree() : nullptr;
auto *TLIWP = P.getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
auto *TLI = TLIWP ? &TLIWP->getTLI(F) : nullptr;
auto *ACWP = P.getAnalysisIfAvailable<AssumptionCacheTracker>();
auto *AC = ACWP ? &ACWP->getAssumptionCache(F) : nullptr;
return {F.getParent()->getDataLayout(), TLI, DT, AC};
}
const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &AR,
const DataLayout &DL) {
return {DL, &AR.TLI, &AR.DT, &AR.AC};
}
template <class T, class... TArgs>
const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &AM,
Function &F) {
auto *DT = AM.template getCachedResult<DominatorTreeAnalysis>(F);
auto *TLI = AM.template getCachedResult<TargetLibraryAnalysis>(F);
auto *AC = AM.template getCachedResult<AssumptionAnalysis>(F);
return {F.getParent()->getDataLayout(), TLI, DT, AC};
}
template const SimplifyQuery getBestSimplifyQuery(AnalysisManager<Function> &,
Function &);
}
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