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llvm-mirror/lib/Analysis/InstructionSimplify.cpp
Johannes Doerfert 86cba7bf5e [InstSimplify] Expose generic interface for replaced operand simplification 
Users, especially the Attributor, might replace multiple operands at
once. The actual implementation of simplifyWithOpReplaced is able to
handle that just fine, the interface was simply not allowing to replace
more than one operand at a time. This is exposing a more generic
interface without intended changes for existing code.

Differential Revision: https://reviews.llvm.org/D106189
2021-07-27 00:56:12 -05:00

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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/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.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/OverflowInstAnalysis.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 *SimplifySelectInst(Value *, Value *, 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".
// Folding select to and/or isn't poison-safe in general; impliesPoison
// checks whether folding it does not convert a well-defined value into
// poison.
if (match(FCmp, m_Zero()) && impliesPoison(TCmp, Cond))
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()) && impliesPoison(FCmp, Cond))
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()->isEntryBlock() && !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 - poison -> poison
// poison - X -> poison
if (isa<PoisonValue>(Op0) || isa<PoisonValue>(Op1))
return PoisonValue::get(Op0->getType());
// 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 * poison -> poison
if (isa<PoisonValue>(Op1))
return Op1;
// 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(Instruction::BinaryOps Opcode, Value *Op0,
Value *Op1, const SimplifyQuery &Q) {
bool IsDiv = (Opcode == Instruction::SDiv || Opcode == Instruction::UDiv);
bool IsSigned = (Opcode == Instruction::SDiv || Opcode == Instruction::SRem);
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);
}
}
// poison / X -> poison
// poison % X -> poison
if (isa<PoisonValue>(Op0))
return Op0;
// 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);
// If X * Y does not overflow, then:
// X * Y / Y -> X
// X * Y % Y -> 0
if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) {
auto *Mul = cast<OverflowingBinaryOperator>(Op0);
// The multiplication can't overflow if it is defined not to, or if
// X == A / Y for some A.
if ((IsSigned && Q.IIQ.hasNoSignedWrap(Mul)) ||
(!IsSigned && Q.IIQ.hasNoUnsignedWrap(Mul)) ||
(IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) ||
(!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1))))) {
return IsDiv ? X : Constant::getNullValue(Op0->getType());
}
}
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(Opcode, Op0, Op1, Q))
return V;
bool IsSigned = Opcode == Instruction::SDiv;
// (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(), 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(Opcode, Op0, Op1, 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;
// poison shift by X -> poison
if (isa<PoisonValue>(Op0))
return Op0;
// 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;
}
/// 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 & poison -> poison
if (isa<PoisonValue>(Op1))
return Op1;
// 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 (isCheckForZeroAndMulWithOverflow(Op0, Op1, true))
return Op1;
if (isCheckForZeroAndMulWithOverflow(Op1, Op0, true))
return Op0;
// A & (-A) = A if A is a power of two or zero.
if (match(Op0, m_Neg(m_Specific(Op1))) ||
match(Op1, m_Neg(m_Specific(Op0)))) {
if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
Q.DT))
return Op0;
if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI,
Q.DT))
return Op1;
}
// 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 | poison -> poison
if (isa<PoisonValue>(Op1))
return Op1;
// 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 (isCheckForZeroAndMulWithOverflow(Op0, Op1, false))
return Op1;
if (isCheckForZeroAndMulWithOverflow(Op1, Op0, false))
return Op0;
// 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.
// icmp poison, X -> poison
if (isa<PoisonValue>(RHS))
return PoisonValue::get(ITy);
// 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;
// TODO: Sink/common this with other potentially expensive calls that use
// ValueTracking? See comment below for isKnownNonEqual().
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));
if (LHS_CR.icmp(Pred, RHS_CR))
return ConstantInt::getTrue(RHS->getContext());
if (LHS_CR.icmp(CmpInst::getInversePredicate(Pred), RHS_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
// This is potentially expensive, and we have already computedKnownBits for
// compares with 0 above here, so only try this for a non-zero compare.
if (ICmpInst::isEquality(Pred) && !match(RHS, m_Zero()) &&
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, poison and fcmp pred poison, x
// fold to poison
if (isa<PoisonValue>(LHS) || isa<PoisonValue>(RHS))
return PoisonValue::get(RetTy);
// 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) {
assert(!Op->getType()->isVectorTy() && "This is not safe for vectors");
// 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; });
if (!AllowRefinement) {
// General InstSimplify functions may refine the result, e.g. by returning
// a constant for a potentially poison value. To avoid this, implement only
// a few non-refining but profitable transforms here.
if (auto *BO = dyn_cast<BinaryOperator>(I)) {
unsigned Opcode = BO->getOpcode();
// id op x -> x, x op id -> x
if (NewOps[0] == ConstantExpr::getBinOpIdentity(Opcode, I->getType()))
return NewOps[1];
if (NewOps[1] == ConstantExpr::getBinOpIdentity(Opcode, I->getType(),
/* RHS */ true))
return NewOps[0];
// x & x -> x, x | x -> x
if ((Opcode == Instruction::And || Opcode == Instruction::Or) &&
NewOps[0] == NewOps[1])
return NewOps[0];
}
if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) {
// getelementptr x, 0 -> x
if (NewOps.size() == 2 && match(NewOps[1], m_Zero()) &&
!GEP->isInBounds())
return NewOps[0];
}
} else 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));
if (isa<SelectInst>(I))
return PreventSelfSimplify(
SimplifySelectInst(NewOps[0], NewOps[1], NewOps[2], 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;
}
// 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 may be unsound, because it only catches some forms of
// refinement.
if (!AllowRefinement && canCreatePoison(cast<Operator>(I)))
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 a scalar 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.
// Note that the equivalence/replacement opportunity does not hold for vectors
// because each element of a vector select is chosen independently.
if (Pred == ICmpInst::ICMP_EQ && !CondVal->getType()->isVectorTy()) {
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 poison, X, Y -> poison
if (isa<PoisonValue>(CondC))
return PoisonValue::get(TrueVal->getType());
// select undef, X, Y -> X or Y
if (Q.isUndefValue(CondC))
return isa<Constant>(FalseVal) ? FalseVal : TrueVal;
// select true, X, Y --> X
// select false, X, Y --> Y
// For vectors, allow undef/poison elements in the condition to match the
// defined elements, so we can eliminate the select.
if (match(CondC, m_One()))
return TrueVal;
if (match(CondC, m_Zero()))
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 poison, we can fold to the other value.
// 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 ?, poison, X -> X
// select ?, undef, X -> X
if (isa<PoisonValue>(TrueVal) ||
(Q.isUndefValue(TrueVal) &&
isGuaranteedNotToBePoison(FalseVal, Q.AC, Q.CxtI, Q.DT)))
return FalseVal;
// select ?, X, poison -> X
// select ?, X, undef -> X
if (isa<PoisonValue>(FalseVal) ||
(Q.isUndefValue(FalseVal) &&
isGuaranteedNotToBePoison(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 (isa<PoisonValue>(TEltC) ||
(Q.isUndefValue(TEltC) && isGuaranteedNotToBePoison(FEltC)))
NewC.push_back(FEltC);
else if (isa<PoisonValue>(FEltC) ||
(Q.isUndefValue(FEltC) && isGuaranteedNotToBePoison(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);
for (Value *Op : Ops) {
// If one of the operands is a vector, the result type is a vector of
// pointers. All vector operands must have the same number of elements.
if (VectorType *VT = dyn_cast<VectorType>(Op->getType())) {
GEPTy = VectorType::get(GEPTy, VT->getElementCount());
break;
}
}
// 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) || any_of(Ops, [](const Value *V) {
return isa<ScalableVectorType>(V->getType());
});
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);
if (Q.isUndefValue(Vec))
return UndefValue::get(VecVTy->getElementType());
}
// 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());
// 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.
unsigned MinNumElts = VecVTy->getElementCount().getKnownMinValue();
if (isa<FixedVectorType>(VecVTy) && IdxC->getValue().uge(MinNumElts))
return PoisonValue::get(VecVTy->getElementType());
// Handle case where an element is extracted from a splat.
if (IdxC->getValue().ult(MinNumElts))
if (auto *Splat = getSplatValue(Vec))
return Splat;
if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue()))
return Elt;
} else {
// The index is not relevant if our vector is a splat.
if (Value *Splat = getSplatValue(Vec))
return Splat;
}
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, ArrayRef<Value *> IncomingValues,
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 : IncomingValues) {
// 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 poison/undef/NaN because the operation itself makes no
/// difference to the result.
static Constant *simplifyFPOp(ArrayRef<Value *> Ops, FastMathFlags FMF,
const SimplifyQuery &Q,
fp::ExceptionBehavior ExBehavior,
RoundingMode Rounding) {
// Poison is independent of anything else. It always propagates from an
// operand to a math result.
if (any_of(Ops, [](Value *V) { return match(V, m_Poison()); }))
return PoisonValue::get(Ops[0]->getType());
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 (isDefaultFPEnvironment(ExBehavior, Rounding)) {
if (IsUndef || IsNan)
return propagateNaN(cast<Constant>(V));
} else if (ExBehavior != fp::ebStrict) {
if (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,
fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
RoundingMode Rounding = RoundingMode::NearestTiesToEven) {
if (isDefaultFPEnvironment(ExBehavior, Rounding))
if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q))
return C;
if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding))
return C;
if (!isDefaultFPEnvironment(ExBehavior, Rounding))
return nullptr;
// 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,
fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
RoundingMode Rounding = RoundingMode::NearestTiesToEven) {
if (isDefaultFPEnvironment(ExBehavior, Rounding))
if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q))
return C;
if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding))
return C;
if (!isDefaultFPEnvironment(ExBehavior, Rounding))
return nullptr;
// 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,
fp::ExceptionBehavior ExBehavior,
RoundingMode Rounding) {
if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding))
return C;
if (!isDefaultFPEnvironment(ExBehavior, Rounding))
return nullptr;
// 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,
fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
RoundingMode Rounding = RoundingMode::NearestTiesToEven) {
if (isDefaultFPEnvironment(ExBehavior, Rounding))
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, ExBehavior, Rounding);
}
Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q,
fp::ExceptionBehavior ExBehavior,
RoundingMode Rounding) {
return ::SimplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
Rounding);
}
Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q,
fp::ExceptionBehavior ExBehavior,
RoundingMode Rounding) {
return ::SimplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
Rounding);
}
Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q,
fp::ExceptionBehavior ExBehavior,
RoundingMode Rounding) {
return ::SimplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
Rounding);
}
Value *llvm::SimplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q,
fp::ExceptionBehavior ExBehavior,
RoundingMode Rounding) {
return ::SimplifyFMAFMul(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
Rounding);
}
static Value *
SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q, unsigned,
fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
RoundingMode Rounding = RoundingMode::NearestTiesToEven) {
if (isDefaultFPEnvironment(ExBehavior, Rounding))
if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q))
return C;
if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding))
return C;
if (!isDefaultFPEnvironment(ExBehavior, Rounding))
return nullptr;
// 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,
fp::ExceptionBehavior ExBehavior,
RoundingMode Rounding) {
return ::SimplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
Rounding);
}
static Value *
SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF,
const SimplifyQuery &Q, unsigned,
fp::ExceptionBehavior ExBehavior = fp::ebIgnore,
RoundingMode Rounding = RoundingMode::NearestTiesToEven) {
if (isDefaultFPEnvironment(ExBehavior, Rounding))
if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q))
return C;
if (Constant *C = simplifyFPOp({Op0, Op1}, FMF, Q, ExBehavior, Rounding))
return C;
if (!isDefaultFPEnvironment(ExBehavior, Rounding))
return nullptr;
// 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,
fp::ExceptionBehavior ExBehavior,
RoundingMode Rounding) {
return ::SimplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit, ExBehavior,
Rounding);
}
//=== 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_Negative(), m_Value(X))))
return X;
if (match(Op0, m_AShr(m_Negative(), m_Value())))
return Constant::getNullValue(ReturnType);
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;
}
case Intrinsic::experimental_vector_extract: {
Type *ReturnType = F->getReturnType();
// (extract_vector (insert_vector _, X, 0), 0) -> X
unsigned IdxN = cast<ConstantInt>(Op1)->getZExtValue();
Value *X = nullptr;
if (match(Op0, m_Intrinsic<Intrinsic::experimental_vector_insert>(
m_Value(), m_Value(X), m_Zero())) &&
IdxN == 0 && X->getType() == ReturnType)
return X;
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::experimental_constrained_fma: {
Value *Op0 = Call->getArgOperand(0);
Value *Op1 = Call->getArgOperand(1);
Value *Op2 = Call->getArgOperand(2);
auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
if (Value *V = simplifyFPOp({Op0, Op1, Op2}, {}, Q,
FPI->getExceptionBehavior().getValue(),
FPI->getRoundingMode().getValue()))
return V;
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, fp::ebIgnore,
RoundingMode::NearestTiesToEven))
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;
}
case Intrinsic::experimental_vector_insert: {
Value *Vec = Call->getArgOperand(0);
Value *SubVec = Call->getArgOperand(1);
Value *Idx = Call->getArgOperand(2);
Type *ReturnType = F->getReturnType();
// (insert_vector Y, (extract_vector X, 0), 0) -> X
// where: Y is X, or Y is undef
unsigned IdxN = cast<ConstantInt>(Idx)->getZExtValue();
Value *X = nullptr;
if (match(SubVec, m_Intrinsic<Intrinsic::experimental_vector_extract>(
m_Value(X), m_Zero())) &&
(Q.isUndefValue(Vec) || Vec == X) && IdxN == 0 &&
X->getType() == ReturnType)
return X;
return nullptr;
}
case Intrinsic::experimental_constrained_fadd: {
auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
return SimplifyFAddInst(FPI->getArgOperand(0), FPI->getArgOperand(1),
FPI->getFastMathFlags(), Q,
FPI->getExceptionBehavior().getValue(),
FPI->getRoundingMode().getValue());
break;
}
case Intrinsic::experimental_constrained_fsub: {
auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
return SimplifyFSubInst(FPI->getArgOperand(0), FPI->getArgOperand(1),
FPI->getFastMathFlags(), Q,
FPI->getExceptionBehavior().getValue(),
FPI->getRoundingMode().getValue());
break;
}
case Intrinsic::experimental_constrained_fmul: {
auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
return SimplifyFMulInst(FPI->getArgOperand(0), FPI->getArgOperand(1),
FPI->getFastMathFlags(), Q,
FPI->getExceptionBehavior().getValue(),
FPI->getRoundingMode().getValue());
break;
}
case Intrinsic::experimental_constrained_fdiv: {
auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
return SimplifyFDivInst(FPI->getArgOperand(0), FPI->getArgOperand(1),
FPI->getFastMathFlags(), Q,
FPI->getExceptionBehavior().getValue(),
FPI->getRoundingMode().getValue());
break;
}
case Intrinsic::experimental_constrained_frem: {
auto *FPI = cast<ConstrainedFPIntrinsic>(Call);
return SimplifyFRemInst(FPI->getArgOperand(0), FPI->getArgOperand(1),
FPI->getFastMathFlags(), Q,
FPI->getExceptionBehavior().getValue(),
FPI->getRoundingMode().getValue());
break;
}
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);
}
static Constant *ConstructLoadOperandConstant(Value *Op) {
SmallVector<Value *, 4> Worklist;
// Invalid IR in unreachable code may contain self-referential values. Don't infinitely loop.
SmallPtrSet<Value *, 4> Visited;
Worklist.push_back(Op);
while (true) {
Value *CurOp = Worklist.back();
if (!Visited.insert(CurOp).second)
return nullptr;
if (isa<Constant>(CurOp))
break;
if (auto *BC = dyn_cast<BitCastOperator>(CurOp)) {
Worklist.push_back(BC->getOperand(0));
} else if (auto *GEP = dyn_cast<GEPOperator>(CurOp)) {
for (unsigned I = 1; I != GEP->getNumOperands(); ++I) {
if (!isa<Constant>(GEP->getOperand(I)))
return nullptr;
}
Worklist.push_back(GEP->getOperand(0));
} else if (auto *II = dyn_cast<IntrinsicInst>(CurOp)) {
if (II->isLaunderOrStripInvariantGroup())
Worklist.push_back(II->getOperand(0));
else
return nullptr;
} else {
return nullptr;
}
}
Constant *NewOp = cast<Constant>(Worklist.pop_back_val());
while (!Worklist.empty()) {
Value *CurOp = Worklist.pop_back_val();
if (isa<BitCastOperator>(CurOp)) {
NewOp = ConstantExpr::getBitCast(NewOp, CurOp->getType());
} else if (auto *GEP = dyn_cast<GEPOperator>(CurOp)) {
SmallVector<Constant *> Idxs;
Idxs.reserve(GEP->getNumOperands() - 1);
for (unsigned I = 1, E = GEP->getNumOperands(); I != E; ++I) {
Idxs.push_back(cast<Constant>(GEP->getOperand(I)));
}
NewOp = ConstantExpr::getGetElementPtr(GEP->getSourceElementType(), NewOp,
Idxs, GEP->isInBounds(),
GEP->getInRangeIndex());
} else {
assert(isa<IntrinsicInst>(CurOp) &&
cast<IntrinsicInst>(CurOp)->isLaunderOrStripInvariantGroup() &&
"expected invariant group intrinsic");
NewOp = ConstantExpr::getBitCast(NewOp, CurOp->getType());
}
}
return NewOp;
}
static Value *SimplifyLoadInst(LoadInst *LI, Value *PtrOp,
const SimplifyQuery &Q) {
if (LI->isVolatile())
return nullptr;
// Try to make the load operand a constant, specifically handle
// invariant.group intrinsics.
auto *PtrOpC = dyn_cast<Constant>(PtrOp);
if (!PtrOpC)
PtrOpC = ConstructLoadOperandConstant(PtrOp);
if (PtrOpC)
return ConstantFoldLoadFromConstPtr(PtrOpC, LI->getType(), Q.DL);
return nullptr;
}
/// See if we can compute a simplified version of this instruction.
/// If not, this returns null.
static Value *simplifyInstructionWithOperands(Instruction *I,
ArrayRef<Value *> NewOps,
const SimplifyQuery &SQ,
OptimizationRemarkEmitter *ORE) {
const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I);
Value *Result = nullptr;
switch (I->getOpcode()) {
default:
if (llvm::all_of(NewOps, [](Value *V) { return isa<Constant>(V); })) {
SmallVector<Constant *, 8> NewConstOps(NewOps.size());
transform(NewOps, NewConstOps.begin(),
[](Value *V) { return cast<Constant>(V); });
Result = ConstantFoldInstOperands(I, NewConstOps, Q.DL, Q.TLI);
}
break;
case Instruction::FNeg:
Result = SimplifyFNegInst(NewOps[0], I->getFastMathFlags(), Q);
break;
case Instruction::FAdd:
Result = SimplifyFAddInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q);
break;
case Instruction::Add:
Result = SimplifyAddInst(
NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)),
Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q);
break;
case Instruction::FSub:
Result = SimplifyFSubInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q);
break;
case Instruction::Sub:
Result = SimplifySubInst(
NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)),
Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q);
break;
case Instruction::FMul:
Result = SimplifyFMulInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q);
break;
case Instruction::Mul:
Result = SimplifyMulInst(NewOps[0], NewOps[1], Q);
break;
case Instruction::SDiv:
Result = SimplifySDivInst(NewOps[0], NewOps[1], Q);
break;
case Instruction::UDiv:
Result = SimplifyUDivInst(NewOps[0], NewOps[1], Q);
break;
case Instruction::FDiv:
Result = SimplifyFDivInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q);
break;
case Instruction::SRem:
Result = SimplifySRemInst(NewOps[0], NewOps[1], Q);
break;
case Instruction::URem:
Result = SimplifyURemInst(NewOps[0], NewOps[1], Q);
break;
case Instruction::FRem:
Result = SimplifyFRemInst(NewOps[0], NewOps[1], I->getFastMathFlags(), Q);
break;
case Instruction::Shl:
Result = SimplifyShlInst(
NewOps[0], NewOps[1], Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)),
Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q);
break;
case Instruction::LShr:
Result = SimplifyLShrInst(NewOps[0], NewOps[1],
Q.IIQ.isExact(cast<BinaryOperator>(I)), Q);
break;
case Instruction::AShr:
Result = SimplifyAShrInst(NewOps[0], NewOps[1],
Q.IIQ.isExact(cast<BinaryOperator>(I)), Q);
break;
case Instruction::And:
Result = SimplifyAndInst(NewOps[0], NewOps[1], Q);
break;
case Instruction::Or:
Result = SimplifyOrInst(NewOps[0], NewOps[1], Q);
break;
case Instruction::Xor:
Result = SimplifyXorInst(NewOps[0], NewOps[1], Q);
break;
case Instruction::ICmp:
Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), NewOps[0],
NewOps[1], Q);
break;
case Instruction::FCmp:
Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), NewOps[0],
NewOps[1], I->getFastMathFlags(), Q);
break;
case Instruction::Select:
Result = SimplifySelectInst(NewOps[0], NewOps[1], NewOps[2], Q);
break;
case Instruction::GetElementPtr: {
Result = SimplifyGEPInst(cast<GetElementPtrInst>(I)->getSourceElementType(),
NewOps, Q);
break;
}
case Instruction::InsertValue: {
InsertValueInst *IV = cast<InsertValueInst>(I);
Result = SimplifyInsertValueInst(NewOps[0], NewOps[1], IV->getIndices(), Q);
break;
}
case Instruction::InsertElement: {
Result = SimplifyInsertElementInst(NewOps[0], NewOps[1], NewOps[2], Q);
break;
}
case Instruction::ExtractValue: {
auto *EVI = cast<ExtractValueInst>(I);
Result = SimplifyExtractValueInst(NewOps[0], EVI->getIndices(), Q);
break;
}
case Instruction::ExtractElement: {
Result = SimplifyExtractElementInst(NewOps[0], NewOps[1], Q);
break;
}
case Instruction::ShuffleVector: {
auto *SVI = cast<ShuffleVectorInst>(I);
Result = SimplifyShuffleVectorInst(
NewOps[0], NewOps[1], SVI->getShuffleMask(), SVI->getType(), Q);
break;
}
case Instruction::PHI:
Result = SimplifyPHINode(cast<PHINode>(I), NewOps, Q);
break;
case Instruction::Call: {
// TODO: Use NewOps
Result = SimplifyCall(cast<CallInst>(I), Q);
break;
}
case Instruction::Freeze:
Result = llvm::SimplifyFreezeInst(NewOps[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(), NewOps[0], I->getType(), Q);
break;
case Instruction::Alloca:
// No simplifications for Alloca and it can't be constant folded.
Result = nullptr;
break;
case Instruction::Load:
Result = SimplifyLoadInst(cast<LoadInst>(I), NewOps[0], Q);
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;
}
Value *llvm::SimplifyInstructionWithOperands(Instruction *I,
ArrayRef<Value *> NewOps,
const SimplifyQuery &SQ,
OptimizationRemarkEmitter *ORE) {
assert(NewOps.size() == I->getNumOperands() &&
"Number of operands should match the instruction!");
return ::simplifyInstructionWithOperands(I, NewOps, SQ, ORE);
}
Value *llvm::SimplifyInstruction(Instruction *I, const SimplifyQuery &SQ,
OptimizationRemarkEmitter *ORE) {
SmallVector<Value *, 8> Ops(I->operands());
return ::simplifyInstructionWithOperands(I, Ops, SQ, ORE);
}
/// 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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