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Diffstat (limited to 'llvm/lib/Analysis/InstructionSimplify.cpp')
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 5518 |
1 files changed, 5518 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp new file mode 100644 index 0000000000000..cb8987721700b --- /dev/null +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -0,0 +1,5518 @@ +//===- InstructionSimplify.cpp - Fold instruction operands ----------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file implements routines for folding instructions into simpler forms +// that do not require creating new instructions. This does constant folding +// ("add i32 1, 1" -> "2") but can also handle non-constant operands, either +// returning a constant ("and i32 %x, 0" -> "0") or an already existing value +// ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been +// simplified: This is usually true and assuming it simplifies the logic (if +// they have not been simplified then results are correct but maybe suboptimal). +// +//===----------------------------------------------------------------------===// + +#include "llvm/Analysis/InstructionSimplify.h" +#include "llvm/ADT/SetVector.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/Analysis/AssumptionCache.h" +#include "llvm/Analysis/CaptureTracking.h" +#include "llvm/Analysis/CmpInstAnalysis.h" +#include "llvm/Analysis/ConstantFolding.h" +#include "llvm/Analysis/LoopAnalysisManager.h" +#include "llvm/Analysis/MemoryBuiltins.h" +#include "llvm/Analysis/ValueTracking.h" +#include "llvm/Analysis/VectorUtils.h" +#include "llvm/IR/ConstantRange.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/Dominators.h" +#include "llvm/IR/GetElementPtrTypeIterator.h" +#include "llvm/IR/GlobalAlias.h" +#include "llvm/IR/InstrTypes.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/Operator.h" +#include "llvm/IR/PatternMatch.h" +#include "llvm/IR/ValueHandle.h" +#include "llvm/Support/KnownBits.h" +#include <algorithm> +using namespace llvm; +using namespace llvm::PatternMatch; + +#define DEBUG_TYPE "instsimplify" + +enum { RecursionLimit = 3 }; + +STATISTIC(NumExpand, "Number of expansions"); +STATISTIC(NumReassoc, "Number of reassociations"); + +static Value *SimplifyAndInst(Value *, Value *, const SimplifyQuery &, unsigned); +static Value *simplifyUnOp(unsigned, Value *, const SimplifyQuery &, unsigned); +static Value *simplifyFPUnOp(unsigned, Value *, const FastMathFlags &, + const SimplifyQuery &, unsigned); +static Value *SimplifyBinOp(unsigned, Value *, Value *, const SimplifyQuery &, + unsigned); +static Value *SimplifyBinOp(unsigned, Value *, Value *, const FastMathFlags &, + const SimplifyQuery &, unsigned); +static Value *SimplifyCmpInst(unsigned, Value *, Value *, const SimplifyQuery &, + unsigned); +static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const SimplifyQuery &Q, unsigned MaxRecurse); +static Value *SimplifyOrInst(Value *, Value *, const SimplifyQuery &, unsigned); +static Value *SimplifyXorInst(Value *, Value *, const SimplifyQuery &, unsigned); +static Value *SimplifyCastInst(unsigned, Value *, Type *, + const SimplifyQuery &, unsigned); +static Value *SimplifyGEPInst(Type *, ArrayRef<Value *>, const SimplifyQuery &, + unsigned); + +static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal, + Value *FalseVal) { + BinaryOperator::BinaryOps BinOpCode; + if (auto *BO = dyn_cast<BinaryOperator>(Cond)) + BinOpCode = BO->getOpcode(); + else + return nullptr; + + CmpInst::Predicate ExpectedPred, Pred1, Pred2; + if (BinOpCode == BinaryOperator::Or) { + ExpectedPred = ICmpInst::ICMP_NE; + } else if (BinOpCode == BinaryOperator::And) { + ExpectedPred = ICmpInst::ICMP_EQ; + } else + return nullptr; + + // %A = icmp eq %TV, %FV + // %B = icmp eq %X, %Y (and one of these is a select operand) + // %C = and %A, %B + // %D = select %C, %TV, %FV + // --> + // %FV + + // %A = icmp ne %TV, %FV + // %B = icmp ne %X, %Y (and one of these is a select operand) + // %C = or %A, %B + // %D = select %C, %TV, %FV + // --> + // %TV + Value *X, *Y; + if (!match(Cond, m_c_BinOp(m_c_ICmp(Pred1, m_Specific(TrueVal), + m_Specific(FalseVal)), + m_ICmp(Pred2, m_Value(X), m_Value(Y)))) || + Pred1 != Pred2 || Pred1 != ExpectedPred) + return nullptr; + + if (X == TrueVal || X == FalseVal || Y == TrueVal || Y == FalseVal) + return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal; + + return nullptr; +} + +/// For a boolean type or a vector of boolean type, return false or a vector +/// with every element false. +static Constant *getFalse(Type *Ty) { + return ConstantInt::getFalse(Ty); +} + +/// For a boolean type or a vector of boolean type, return true or a vector +/// with every element true. +static Constant *getTrue(Type *Ty) { + return ConstantInt::getTrue(Ty); +} + +/// isSameCompare - Is V equivalent to the comparison "LHS Pred RHS"? +static bool isSameCompare(Value *V, CmpInst::Predicate Pred, Value *LHS, + Value *RHS) { + CmpInst *Cmp = dyn_cast<CmpInst>(V); + if (!Cmp) + return false; + CmpInst::Predicate CPred = Cmp->getPredicate(); + Value *CLHS = Cmp->getOperand(0), *CRHS = Cmp->getOperand(1); + if (CPred == Pred && CLHS == LHS && CRHS == RHS) + return true; + return CPred == CmpInst::getSwappedPredicate(Pred) && CLHS == RHS && + CRHS == LHS; +} + +/// Does the given value dominate the specified phi node? +static bool valueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) { + Instruction *I = dyn_cast<Instruction>(V); + if (!I) + // Arguments and constants dominate all instructions. + return true; + + // If we are processing instructions (and/or basic blocks) that have not been + // fully added to a function, the parent nodes may still be null. Simply + // return the conservative answer in these cases. + if (!I->getParent() || !P->getParent() || !I->getFunction()) + return false; + + // If we have a DominatorTree then do a precise test. + if (DT) + return DT->dominates(I, P); + + // Otherwise, if the instruction is in the entry block and is not an invoke, + // then it obviously dominates all phi nodes. + if (I->getParent() == &I->getFunction()->getEntryBlock() && + !isa<InvokeInst>(I)) + return true; + + return false; +} + +/// Simplify "A op (B op' C)" by distributing op over op', turning it into +/// "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is +/// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS. +/// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)". +/// Returns the simplified value, or null if no simplification was performed. +static Value *ExpandBinOp(Instruction::BinaryOps Opcode, Value *LHS, Value *RHS, + 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; + + // Check whether the expression has the form "(A op' B) op C". + if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS)) + if (Op0->getOpcode() == OpcodeToExpand) { + // It does! Try turning it into "(A op C) op' (B op C)". + Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS; + // Do "A op C" and "B op C" both simplify? + if (Value *L = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) + if (Value *R = SimplifyBinOp(Opcode, B, C, Q, MaxRecurse)) { + // They do! Return "L op' R" if it simplifies or is already available. + // If "L op' R" equals "A op' B" then "L op' R" is just the LHS. + if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand) + && L == B && R == A)) { + ++NumExpand; + return LHS; + } + // Otherwise return "L op' R" if it simplifies. + if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) { + ++NumExpand; + return V; + } + } + } + + // Check whether the expression has the form "A op (B op' C)". + if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS)) + if (Op1->getOpcode() == OpcodeToExpand) { + // It does! Try turning it into "(A op B) op' (A op C)". + Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1); + // Do "A op B" and "A op C" both simplify? + if (Value *L = SimplifyBinOp(Opcode, A, B, Q, MaxRecurse)) + if (Value *R = SimplifyBinOp(Opcode, A, C, Q, MaxRecurse)) { + // They do! Return "L op' R" if it simplifies or is already available. + // If "L op' R" equals "B op' C" then "L op' R" is just the RHS. + if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand) + && L == C && R == B)) { + ++NumExpand; + return RHS; + } + // Otherwise return "L op' R" if it simplifies. + if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, Q, MaxRecurse)) { + ++NumExpand; + return V; + } + } + } + + return nullptr; +} + +/// Generic simplifications for associative binary operations. +/// Returns the simpler value, or null if none was found. +static Value *SimplifyAssociativeBinOp(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 && isa<UndefValue>(TV)) + return FV; + if (FV && isa<UndefValue>(FV)) + return TV; + + // If applying the operation did not change the true and false select values, + // then the result of the binop is the select itself. + if (TV == SI->getTrueValue() && FV == SI->getFalseValue()) + return SI; + + // If one branch simplified and the other did not, and the simplified + // value is equal to the unsimplified one, return the simplified value. + // For example, select (cond, X, X & Z) & Z -> X & Z. + if ((FV && !TV) || (TV && !FV)) { + // Check that the simplified value has the form "X op Y" where "op" is the + // same as the original operation. + Instruction *Simplified = dyn_cast<Instruction>(FV ? FV : TV); + if (Simplified && Simplified->getOpcode() == 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. +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 = SimplifyCmpInst(Pred, TV, RHS, Q, MaxRecurse); + if (TCmp == Cond) { + // It not only simplified, it simplified to the select condition. Replace + // it with 'true'. + TCmp = getTrue(Cond->getType()); + } else if (!TCmp) { + // It didn't simplify. However if "cmp TV, RHS" is equal to the select + // condition then we can replace it with 'true'. Otherwise give up. + if (!isSameCompare(Cond, Pred, TV, RHS)) + return nullptr; + TCmp = getTrue(Cond->getType()); + } + + // Does "cmp FV, RHS" simplify? + Value *FCmp = SimplifyCmpInst(Pred, FV, RHS, Q, MaxRecurse); + if (FCmp == Cond) { + // It not only simplified, it simplified to the select condition. Replace + // it with 'false'. + FCmp = getFalse(Cond->getType()); + } else if (!FCmp) { + // It didn't simplify. However if "cmp FV, RHS" is equal to the select + // condition then we can replace it with 'false'. Otherwise give up. + if (!isSameCompare(Cond, Pred, FV, RHS)) + return nullptr; + FCmp = getFalse(Cond->getType()); + } + + // If both sides simplified to the same value, then use it as the result of + // the original comparison. + if (TCmp == FCmp) + return TCmp; + + // The remaining cases only make sense if the select condition has the same + // type as the result of the comparison, so bail out if this is not so. + if (Cond->getType()->isVectorTy() != RHS->getType()->isVectorTy()) + return nullptr; + // If the false value simplified to false, then the result of the compare + // is equal to "Cond && TCmp". This also catches the case when the false + // value simplified to false and the true value to true, returning "Cond". + if (match(FCmp, m_Zero())) + if (Value *V = SimplifyAndInst(Cond, TCmp, Q, MaxRecurse)) + return V; + // If the true value simplified to true, then the result of the compare + // is equal to "Cond || FCmp". + if (match(TCmp, m_One())) + if (Value *V = SimplifyOrInst(Cond, FCmp, Q, MaxRecurse)) + return V; + // Finally, if the false value simplified to true and the true value to + // false, then the result of the compare is equal to "!Cond". + if (match(FCmp, m_One()) && match(TCmp, m_Zero())) + if (Value *V = + SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()), + Q, MaxRecurse)) + return V; + + return nullptr; +} + +/// In the case of a binary operation with an operand that is a PHI instruction, +/// try to simplify the binop by seeing whether evaluating it on the incoming +/// phi values yields the same result for every value. If so returns the common +/// value, otherwise returns null. +static Value *ThreadBinOpOverPHI(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 (Value *Incoming : PI->incoming_values()) { + // If the incoming value is the phi node itself, it can safely be skipped. + if (Incoming == PI) continue; + Value *V = SimplifyCmpInst(Pred, Incoming, RHS, Q, MaxRecurse); + // If the operation failed to simplify, or simplified to a different value + // to previously, then give up. + if (!V || (CommonValue && V != CommonValue)) + return nullptr; + CommonValue = V; + } + + return CommonValue; +} + +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 (match(Op1, m_Undef())) + 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 *IntPtrTy = DL.getIntPtrType(V->getType())->getScalarType(); + APInt Offset = APInt::getNullValue(IntPtrTy->getIntegerBitWidth()); + + V = V->stripAndAccumulateConstantOffsets(DL, Offset, AllowNonInbounds); + // As that strip may trace through `addrspacecast`, need to sext or trunc + // the offset calculated. + IntPtrTy = DL.getIntPtrType(V->getType())->getScalarType(); + Offset = Offset.sextOrTrunc(IntPtrTy->getIntegerBitWidth()); + + Constant *OffsetIntPtr = ConstantInt::get(IntPtrTy, Offset); + if (V->getType()->isVectorTy()) + return ConstantVector::getSplat(V->getType()->getVectorNumElements(), + OffsetIntPtr); + return OffsetIntPtr; +} + +/// Compute the constant difference between two pointer values. +/// If the difference is not a constant, returns zero. +static Constant *computePointerDifference(const DataLayout &DL, Value *LHS, + Value *RHS) { + Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS); + Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS); + + // If LHS and RHS are not related via constant offsets to the same base + // value, there is nothing we can do here. + if (LHS != RHS) + return nullptr; + + // Otherwise, the difference of LHS - RHS can be computed as: + // LHS - RHS + // = (LHSOffset + Base) - (RHSOffset + Base) + // = LHSOffset - RHSOffset + return ConstantExpr::getSub(LHSOffset, RHSOffset); +} + +/// Given operands for a Sub, see if we can fold the result. +/// If not, this returns null. +static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, + const SimplifyQuery &Q, unsigned MaxRecurse) { + if (Constant *C = foldOrCommuteConstant(Instruction::Sub, Op0, Op1, Q)) + return C; + + // X - undef -> undef + // undef - X -> undef + if (match(Op0, m_Undef()) || match(Op1, m_Undef())) + return UndefValue::get(Op0->getType()); + + // X - 0 -> X + if (match(Op1, m_Zero())) + return Op0; + + // X - X -> 0 + if (Op0 == Op1) + return Constant::getNullValue(Op0->getType()); + + // Is this a negation? + if (match(Op0, m_Zero())) { + // 0 - X -> 0 if the sub is NUW. + if (isNUW) + return Constant::getNullValue(Op0->getType()); + + KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); + if (Known.Zero.isMaxSignedValue()) { + // Op1 is either 0 or the minimum signed value. If the sub is NSW, then + // Op1 must be 0 because negating the minimum signed value is undefined. + if (isNSW) + return Constant::getNullValue(Op0->getType()); + + // 0 - X -> X if X is 0 or the minimum signed value. + return Op1; + } + } + + // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies. + // For example, (X + Y) - Y -> X; (Y + X) - Y -> X + Value *X = nullptr, *Y = nullptr, *Z = Op1; + if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z + // See if "V === Y - Z" simplifies. + if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, Q, MaxRecurse-1)) + // It does! Now see if "X + V" simplifies. + if (Value *W = SimplifyBinOp(Instruction::Add, X, V, Q, MaxRecurse-1)) { + // It does, we successfully reassociated! + ++NumReassoc; + return W; + } + // See if "V === X - Z" simplifies. + if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) + // It does! Now see if "Y + V" simplifies. + if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, Q, MaxRecurse-1)) { + // It does, we successfully reassociated! + ++NumReassoc; + return W; + } + } + + // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies. + // For example, X - (X + 1) -> -1 + X = Op0; + if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z) + // See if "V === X - Y" simplifies. + if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) + // It does! Now see if "V - Z" simplifies. + if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, Q, MaxRecurse-1)) { + // It does, we successfully reassociated! + ++NumReassoc; + return W; + } + // See if "V === X - Z" simplifies. + if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, Q, MaxRecurse-1)) + // It does! Now see if "V - Y" simplifies. + if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, Q, MaxRecurse-1)) { + // It does, we successfully reassociated! + ++NumReassoc; + return W; + } + } + + // Z - (X - Y) -> (Z - X) + Y if everything simplifies. + // For example, X - (X - Y) -> Y. + Z = Op0; + if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y) + // See if "V === Z - X" simplifies. + if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, Q, MaxRecurse-1)) + // It does! Now see if "V + Y" simplifies. + if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, Q, MaxRecurse-1)) { + // It does, we successfully reassociated! + ++NumReassoc; + return W; + } + + // trunc(X) - trunc(Y) -> trunc(X - Y) if everything simplifies. + if (MaxRecurse && match(Op0, m_Trunc(m_Value(X))) && + match(Op1, m_Trunc(m_Value(Y)))) + if (X->getType() == Y->getType()) + // See if "V === X - Y" simplifies. + if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, Q, MaxRecurse-1)) + // It does! Now see if "trunc V" simplifies. + if (Value *W = SimplifyCastInst(Instruction::Trunc, V, Op0->getType(), + Q, MaxRecurse - 1)) + // It does, return the simplified "trunc V". + return W; + + // Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...). + if (match(Op0, m_PtrToInt(m_Value(X))) && + match(Op1, m_PtrToInt(m_Value(Y)))) + if (Constant *Result = computePointerDifference(Q.DL, X, Y)) + return ConstantExpr::getIntegerCast(Result, Op0->getType(), true); + + // i1 sub -> xor. + if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1)) + if (Value *V = SimplifyXorInst(Op0, Op1, Q, MaxRecurse-1)) + return V; + + // Threading Sub over selects and phi nodes is pointless, so don't bother. + // Threading over the select in "A - select(cond, B, C)" means evaluating + // "A-B" and "A-C" and seeing if they are equal; but they are equal if and + // only if B and C are equal. If B and C are equal then (since we assume + // that operands have already been simplified) "select(cond, B, C)" should + // have been simplified to the common value of B and C already. Analysing + // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly + // for threading over phi nodes. + + return nullptr; +} + +Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW, + const SimplifyQuery &Q) { + return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, Q, RecursionLimit); +} + +/// Given operands for a Mul, see if we can fold the result. +/// If not, this returns null. +static Value *SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, + unsigned MaxRecurse) { + if (Constant *C = foldOrCommuteConstant(Instruction::Mul, Op0, Op1, Q)) + return C; + + // X * undef -> 0 + // X * 0 -> 0 + if (match(Op1, m_CombineOr(m_Undef(), 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 = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add, + Q, MaxRecurse)) + return V; + + // If the operation is with the result of a select instruction, check whether + // operating on either branch of the select always yields the same value. + if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) + if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, Q, + MaxRecurse)) + return V; + + // If the operation is with the result of a phi instruction, check whether + // operating on all incoming values of the phi always yields the same value. + if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) + if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, Q, + MaxRecurse)) + return V; + + return nullptr; +} + +Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { + return ::SimplifyMulInst(Op0, Op1, Q, RecursionLimit); +} + +/// Check for common or similar folds of integer division or integer remainder. +/// This applies to all 4 opcodes (sdiv/udiv/srem/urem). +static Value *simplifyDivRem(Value *Op0, Value *Op1, bool IsDiv) { + Type *Ty = Op0->getType(); + + // X / undef -> undef + // X % undef -> undef + if (match(Op1, m_Undef())) + return Op1; + + // X / 0 -> undef + // X % 0 -> undef + // We don't need to preserve faults! + if (match(Op1, m_Zero())) + return UndefValue::get(Ty); + + // If any element of a constant divisor vector is zero or undef, the whole op + // is undef. + auto *Op1C = dyn_cast<Constant>(Op1); + if (Op1C && Ty->isVectorTy()) { + unsigned NumElts = Ty->getVectorNumElements(); + for (unsigned i = 0; i != NumElts; ++i) { + Constant *Elt = Op1C->getAggregateElement(i); + if (Elt && (Elt->isNullValue() || isa<UndefValue>(Elt))) + return UndefValue::get(Ty); + } + } + + // undef / X -> 0 + // undef % X -> 0 + if (match(Op0, m_Undef())) + return Constant::getNullValue(Ty); + + // 0 / X -> 0 + // 0 % X -> 0 + if (match(Op0, m_Zero())) + return Constant::getNullValue(Op0->getType()); + + // X / X -> 1 + // X % X -> 0 + if (Op0 == Op1) + return IsDiv ? ConstantInt::get(Ty, 1) : Constant::getNullValue(Ty); + + // X / 1 -> X + // X % 1 -> 0 + // If this is a boolean op (single-bit element type), we can't have + // division-by-zero or remainder-by-zero, so assume the divisor is 1. + // Similarly, if we're zero-extending a boolean divisor, then assume it's a 1. + Value *X; + if (match(Op1, m_One()) || Ty->isIntOrIntVectorTy(1) || + (match(Op1, m_ZExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))) + return IsDiv ? Op0 : Constant::getNullValue(Ty); + + return nullptr; +} + +/// Given a predicate and two operands, return true if the comparison is true. +/// This is a helper for div/rem simplification where we return some other value +/// when we can prove a relationship between the operands. +static bool isICmpTrue(ICmpInst::Predicate Pred, Value *LHS, Value *RHS, + const SimplifyQuery &Q, unsigned MaxRecurse) { + Value *V = SimplifyICmpInst(Pred, LHS, RHS, Q, MaxRecurse); + Constant *C = dyn_cast_or_null<Constant>(V); + return (C && C->isAllOnesValue()); +} + +/// Return true if we can simplify X / Y to 0. Remainder can adapt that answer +/// to simplify X % Y to X. +static bool isDivZero(Value *X, Value *Y, const SimplifyQuery &Q, + unsigned MaxRecurse, bool IsSigned) { + // Recursion is always used, so bail out at once if we already hit the limit. + if (!MaxRecurse--) + return false; + + if (IsSigned) { + // |X| / |Y| --> 0 + // + // We require that 1 operand is a simple constant. That could be extended to + // 2 variables if we computed the sign bit for each. + // + // Make sure that a constant is not the minimum signed value because taking + // the abs() of that is undefined. + Type *Ty = X->getType(); + const APInt *C; + if (match(X, m_APInt(C)) && !C->isMinSignedValue()) { + // Is the variable divisor magnitude always greater than the constant + // dividend magnitude? + // |Y| > |C| --> Y < -abs(C) or Y > abs(C) + Constant *PosDividendC = ConstantInt::get(Ty, C->abs()); + Constant *NegDividendC = ConstantInt::get(Ty, -C->abs()); + if (isICmpTrue(CmpInst::ICMP_SLT, Y, NegDividendC, Q, MaxRecurse) || + isICmpTrue(CmpInst::ICMP_SGT, Y, PosDividendC, Q, MaxRecurse)) + return true; + } + if (match(Y, m_APInt(C))) { + // Special-case: we can't take the abs() of a minimum signed value. If + // that's the divisor, then all we have to do is prove that the dividend + // is also not the minimum signed value. + if (C->isMinSignedValue()) + return isICmpTrue(CmpInst::ICMP_NE, X, Y, Q, MaxRecurse); + + // Is the variable dividend magnitude always less than the constant + // divisor magnitude? + // |X| < |C| --> X > -abs(C) and X < abs(C) + Constant *PosDivisorC = ConstantInt::get(Ty, C->abs()); + Constant *NegDivisorC = ConstantInt::get(Ty, -C->abs()); + if (isICmpTrue(CmpInst::ICMP_SGT, X, NegDivisorC, Q, MaxRecurse) && + isICmpTrue(CmpInst::ICMP_SLT, X, PosDivisorC, Q, MaxRecurse)) + return true; + } + return false; + } + + // IsSigned == false. + // Is the dividend unsigned less than the divisor? + return isICmpTrue(ICmpInst::ICMP_ULT, X, Y, Q, MaxRecurse); +} + +/// These are simplifications common to SDiv and UDiv. +static Value *simplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, + const SimplifyQuery &Q, unsigned MaxRecurse) { + if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) + return C; + + if (Value *V = simplifyDivRem(Op0, Op1, true)) + return V; + + bool IsSigned = Opcode == Instruction::SDiv; + + // (X * Y) / Y -> X if the multiplication does not overflow. + Value *X; + if (match(Op0, m_c_Mul(m_Value(X), m_Specific(Op1)))) { + auto *Mul = cast<OverflowingBinaryOperator>(Op0); + // If the Mul does not overflow, then we are good to go. + if ((IsSigned && Q.IIQ.hasNoSignedWrap(Mul)) || + (!IsSigned && Q.IIQ.hasNoUnsignedWrap(Mul))) + return X; + // If X has the form X = A / Y, then X * Y cannot overflow. + if ((IsSigned && match(X, m_SDiv(m_Value(), m_Specific(Op1)))) || + (!IsSigned && match(X, m_UDiv(m_Value(), m_Specific(Op1))))) + return X; + } + + // (X rem Y) / Y -> 0 + if ((IsSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) || + (!IsSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1))))) + return Constant::getNullValue(Op0->getType()); + + // (X /u C1) /u C2 -> 0 if C1 * C2 overflow + ConstantInt *C1, *C2; + if (!IsSigned && match(Op0, m_UDiv(m_Value(X), m_ConstantInt(C1))) && + match(Op1, m_ConstantInt(C2))) { + bool Overflow; + (void)C1->getValue().umul_ov(C2->getValue(), Overflow); + if (Overflow) + return Constant::getNullValue(Op0->getType()); + } + + // If the operation is with the result of a select instruction, check whether + // operating on either branch of the select always yields the same value. + if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) + if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) + return V; + + // If the operation is with the result of a phi instruction, check whether + // operating on all incoming values of the phi always yields the same value. + if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) + if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) + return V; + + if (isDivZero(Op0, Op1, Q, MaxRecurse, IsSigned)) + return Constant::getNullValue(Op0->getType()); + + return nullptr; +} + +/// These are simplifications common to SRem and URem. +static Value *simplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1, + const SimplifyQuery &Q, unsigned MaxRecurse) { + if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) + return C; + + if (Value *V = simplifyDivRem(Op0, Op1, false)) + 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 undef. +static bool isUndefShift(Value *Amount) { + Constant *C = dyn_cast<Constant>(Amount); + if (!C) + return false; + + // X shift by undef -> undef because it may shift by the bitwidth. + if (isa<UndefValue>(C)) + return true; + + // Shifting by the bitwidth or more is undefined. + if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) + if (CI->getValue().getLimitedValue() >= + CI->getType()->getScalarSizeInBits()) + return true; + + // If all lanes of a vector shift are undefined the whole shift is. + if (isa<ConstantVector>(C) || isa<ConstantDataVector>(C)) { + for (unsigned I = 0, E = C->getType()->getVectorNumElements(); I != E; ++I) + if (!isUndefShift(C->getAggregateElement(I))) + return false; + return true; + } + + return false; +} + +/// Given operands for an Shl, LShr or AShr, see if we can fold the result. +/// If not, this returns null. +static Value *SimplifyShift(Instruction::BinaryOps Opcode, Value *Op0, + Value *Op1, const SimplifyQuery &Q, unsigned MaxRecurse) { + if (Constant *C = foldOrCommuteConstant(Opcode, Op0, Op1, Q)) + return C; + + // 0 shift by X -> 0 + if (match(Op0, m_Zero())) + return Constant::getNullValue(Op0->getType()); + + // X shift by 0 -> X + // Shift-by-sign-extended bool must be shift-by-0 because shift-by-all-ones + // would be poison. + Value *X; + if (match(Op1, m_Zero()) || + (match(Op1, m_SExt(m_Value(X))) && X->getType()->isIntOrIntVectorTy(1))) + return Op0; + + // Fold undefined shifts. + if (isUndefShift(Op1)) + return UndefValue::get(Op0->getType()); + + // If the operation is with the result of a select instruction, check whether + // operating on either branch of the select always yields the same value. + if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) + if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, Q, MaxRecurse)) + return V; + + // If the operation is with the result of a phi instruction, check whether + // operating on all incoming values of the phi always yields the same value. + if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) + if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, Q, MaxRecurse)) + return V; + + // If any bits in the shift amount make that value greater than or equal to + // the number of bits in the type, the shift is undefined. + KnownBits Known = computeKnownBits(Op1, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); + if (Known.One.getLimitedValue() >= Known.getBitWidth()) + return UndefValue::get(Op0->getType()); + + // If all valid bits in the shift amount are known zero, the first operand is + // unchanged. + unsigned NumValidShiftBits = Log2_32_Ceil(Known.getBitWidth()); + if (Known.countMinTrailingZeros() >= NumValidShiftBits) + return Op0; + + 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, Q, MaxRecurse)) + return V; + + // X >> X -> 0 + if (Op0 == Op1) + return Constant::getNullValue(Op0->getType()); + + // undef >> X -> 0 + // undef >> X -> undef (if it's exact) + if (match(Op0, m_Undef())) + return isExact ? Op0 : Constant::getNullValue(Op0->getType()); + + // The low bit cannot be shifted out of an exact shift if it is set. + if (isExact) { + 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, Q, MaxRecurse)) + return V; + + // undef << X -> 0 + // undef << X -> undef if (if it's NSW/NUW) + if (match(Op0, m_Undef())) + return isNSW || isNUW ? Op0 : Constant::getNullValue(Op0->getType()); + + // (X >> A) << A -> X + Value *X; + if (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)) { + if (UnsignedICmp->getOperand(0) != A) + UnsignedPred = ICmpInst::getSwappedPredicate(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 (UnsignedICmp->getOperand(0) != Y) + UnsignedPred = ICmpInst::getSwappedPredicate(UnsignedPred); + + 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 --> 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 --> 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; + + // 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 --> 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 --> 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; +} + +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 = 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 = simplifyAndOrOfICmpsWithZero(Op0, Op1, false)) + return X; + + if (Value *X = simplifyOrOfICmpsWithAdd(Op0, Op1, Q.IIQ)) + return X; + if (Value *X = simplifyOrOfICmpsWithAdd(Op1, Op0, Q.IIQ)) + return X; + + return nullptr; +} + +static Value *simplifyAndOrOfFCmps(const TargetLibraryInfo *TLI, + FCmpInst *LHS, FCmpInst *RHS, bool IsAnd) { + Value *LHS0 = LHS->getOperand(0), *LHS1 = LHS->getOperand(1); + Value *RHS0 = RHS->getOperand(0), *RHS1 = RHS->getOperand(1); + if (LHS0->getType() != RHS0->getType()) + return nullptr; + + FCmpInst::Predicate PredL = LHS->getPredicate(), PredR = RHS->getPredicate(); + if ((PredL == FCmpInst::FCMP_ORD && PredR == FCmpInst::FCMP_ORD && IsAnd) || + (PredL == FCmpInst::FCMP_UNO && PredR == FCmpInst::FCMP_UNO && !IsAnd)) { + // (fcmp ord NNAN, X) & (fcmp ord X, Y) --> fcmp ord X, Y + // (fcmp ord NNAN, X) & (fcmp ord Y, X) --> fcmp ord Y, X + // (fcmp ord X, NNAN) & (fcmp ord X, Y) --> fcmp ord X, Y + // (fcmp ord X, NNAN) & (fcmp ord Y, X) --> fcmp ord Y, X + // (fcmp uno NNAN, X) | (fcmp uno X, Y) --> fcmp uno X, Y + // (fcmp uno NNAN, X) | (fcmp uno Y, X) --> fcmp uno Y, X + // (fcmp uno X, NNAN) | (fcmp uno X, Y) --> fcmp uno X, Y + // (fcmp uno X, NNAN) | (fcmp uno Y, X) --> fcmp uno Y, X + if ((isKnownNeverNaN(LHS0, TLI) && (LHS1 == RHS0 || LHS1 == RHS1)) || + (isKnownNeverNaN(LHS1, TLI) && (LHS0 == RHS0 || LHS0 == RHS1))) + return RHS; + + // (fcmp ord X, Y) & (fcmp ord NNAN, X) --> fcmp ord X, Y + // (fcmp ord Y, X) & (fcmp ord NNAN, X) --> fcmp ord Y, X + // (fcmp ord X, Y) & (fcmp ord X, NNAN) --> fcmp ord X, Y + // (fcmp ord Y, X) & (fcmp ord X, NNAN) --> fcmp ord Y, X + // (fcmp uno X, Y) | (fcmp uno NNAN, X) --> fcmp uno X, Y + // (fcmp uno Y, X) | (fcmp uno NNAN, X) --> fcmp uno Y, X + // (fcmp uno X, Y) | (fcmp uno X, NNAN) --> fcmp uno X, Y + // (fcmp uno Y, X) | (fcmp uno X, NNAN) --> fcmp uno Y, X + if ((isKnownNeverNaN(RHS0, TLI) && (RHS1 == LHS0 || RHS1 == LHS1)) || + (isKnownNeverNaN(RHS1, TLI) && (RHS0 == LHS0 || RHS0 == LHS1))) + return LHS; + } + + return nullptr; +} + +static Value *simplifyAndOrOfCmps(const SimplifyQuery &Q, + Value *Op0, Value *Op1, bool IsAnd) { + // Look through casts of the 'and' operands to find compares. + auto *Cast0 = dyn_cast<CastInst>(Op0); + auto *Cast1 = dyn_cast<CastInst>(Op1); + if (Cast0 && Cast1 && Cast0->getOpcode() == Cast1->getOpcode() && + Cast0->getSrcTy() == Cast1->getSrcTy()) { + Op0 = Cast0->getOperand(0); + Op1 = Cast1->getOperand(0); + } + + Value *V = nullptr; + auto *ICmp0 = dyn_cast<ICmpInst>(Op0); + auto *ICmp1 = dyn_cast<ICmpInst>(Op1); + if (ICmp0 && ICmp1) + V = IsAnd ? simplifyAndOfICmps(ICmp0, ICmp1, Q) + : simplifyOrOfICmps(ICmp0, ICmp1, Q); + + auto *FCmp0 = dyn_cast<FCmpInst>(Op0); + auto *FCmp1 = dyn_cast<FCmpInst>(Op1); + if (FCmp0 && FCmp1) + V = simplifyAndOrOfFCmps(Q.TLI, FCmp0, FCmp1, IsAnd); + + if (!V) + return nullptr; + if (!Cast0) + return V; + + // If we looked through casts, we can only handle a constant simplification + // because we are not allowed to create a cast instruction here. + if (auto *C = dyn_cast<Constant>(V)) + return ConstantExpr::getCast(Cast0->getOpcode(), C, Cast0->getType()); + + return nullptr; +} + +/// Check that the Op1 is in expected form, i.e.: +/// %Agg = tail call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %???) +/// %Op1 = extractvalue { i4, i1 } %Agg, 1 +static bool omitCheckForZeroBeforeMulWithOverflowInternal(Value *Op1, + Value *X) { + auto *Extract = dyn_cast<ExtractValueInst>(Op1); + // We should only be extracting the overflow bit. + if (!Extract || !Extract->getIndices().equals(1)) + return false; + Value *Agg = Extract->getAggregateOperand(); + // This should be a multiplication-with-overflow intrinsic. + if (!match(Agg, m_CombineOr(m_Intrinsic<Intrinsic::umul_with_overflow>(), + m_Intrinsic<Intrinsic::smul_with_overflow>()))) + return false; + // One of its multipliers should be the value we checked for zero before. + if (!match(Agg, m_CombineOr(m_Argument<0>(m_Specific(X)), + m_Argument<1>(m_Specific(X))))) + return false; + return true; +} + +/// The @llvm.[us]mul.with.overflow intrinsic could have been folded from some +/// other form of check, e.g. one that was using division; it may have been +/// guarded against division-by-zero. We can drop that check now. +/// Look for: +/// %Op0 = icmp ne i4 %X, 0 +/// %Agg = tail call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %???) +/// %Op1 = extractvalue { i4, i1 } %Agg, 1 +/// %??? = and i1 %Op0, %Op1 +/// We can just return %Op1 +static Value *omitCheckForZeroBeforeMulWithOverflow(Value *Op0, Value *Op1) { + ICmpInst::Predicate Pred; + Value *X; + if (!match(Op0, m_ICmp(Pred, m_Value(X), m_Zero())) || + Pred != ICmpInst::Predicate::ICMP_NE) + return nullptr; + // Is Op1 in expected form? + if (!omitCheckForZeroBeforeMulWithOverflowInternal(Op1, X)) + return nullptr; + // Can omit 'and', and just return the overflow bit. + return Op1; +} + +/// The @llvm.[us]mul.with.overflow intrinsic could have been folded from some +/// other form of check, e.g. one that was using division; it may have been +/// guarded against division-by-zero. We can drop that check now. +/// Look for: +/// %Op0 = icmp eq i4 %X, 0 +/// %Agg = tail call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %???) +/// %Op1 = extractvalue { i4, i1 } %Agg, 1 +/// %NotOp1 = xor i1 %Op1, true +/// %or = or i1 %Op0, %NotOp1 +/// We can just return %NotOp1 +static Value *omitCheckForZeroBeforeInvertedMulWithOverflow(Value *Op0, + Value *NotOp1) { + ICmpInst::Predicate Pred; + Value *X; + if (!match(Op0, m_ICmp(Pred, m_Value(X), m_Zero())) || + Pred != ICmpInst::Predicate::ICMP_EQ) + return nullptr; + // We expect the other hand of an 'or' to be a 'not'. + Value *Op1; + if (!match(NotOp1, m_Not(m_Value(Op1)))) + return nullptr; + // Is Op1 in expected form? + if (!omitCheckForZeroBeforeMulWithOverflowInternal(Op1, X)) + return nullptr; + // Can omit 'and', and just return the inverted overflow bit. + return NotOp1; +} + +/// Given operands for an And, see if we can fold the result. +/// If not, this returns null. +static Value *SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, + unsigned MaxRecurse) { + if (Constant *C = foldOrCommuteConstant(Instruction::And, Op0, Op1, Q)) + return C; + + // X & undef -> 0 + if (match(Op1, m_Undef())) + return Constant::getNullValue(Op0->getType()); + + // X & X = X + if (Op0 == Op1) + return Op0; + + // X & 0 = 0 + if (match(Op1, m_Zero())) + return 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; + + // A mask that only clears known zeros of a shifted value is a no-op. + Value *X; + const APInt *Mask; + const APInt *ShAmt; + if (match(Op1, m_APInt(Mask))) { + // If all bits in the inverted and shifted mask are clear: + // and (shl X, ShAmt), Mask --> shl X, ShAmt + if (match(Op0, m_Shl(m_Value(X), m_APInt(ShAmt))) && + (~(*Mask)).lshr(*ShAmt).isNullValue()) + return Op0; + + // If all bits in the inverted and shifted mask are clear: + // and (lshr X, ShAmt), Mask --> lshr X, ShAmt + if (match(Op0, m_LShr(m_Value(X), m_APInt(ShAmt))) && + (~(*Mask)).shl(*ShAmt).isNullValue()) + return Op0; + } + + // If we have a multiplication overflow check that is being 'and'ed with a + // check that one of the multipliers is not zero, we can omit the 'and', and + // only keep the overflow check. + if (Value *V = omitCheckForZeroBeforeMulWithOverflow(Op0, Op1)) + return V; + if (Value *V = omitCheckForZeroBeforeMulWithOverflow(Op1, Op0)) + return V; + + // A & (-A) = A if A is a power of two or zero. + if (match(Op0, m_Neg(m_Specific(Op1))) || + match(Op1, m_Neg(m_Specific(Op0)))) { + if (isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, + Q.DT)) + return Op0; + if (isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, + Q.DT)) + return Op1; + } + + // This is a similar pattern used for checking if a value is a power-of-2: + // (A - 1) & A --> 0 (if A is a power-of-2 or 0) + // A & (A - 1) --> 0 (if A is a power-of-2 or 0) + if (match(Op0, m_Add(m_Specific(Op1), m_AllOnes())) && + isKnownToBeAPowerOfTwo(Op1, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) + return Constant::getNullValue(Op1->getType()); + if (match(Op1, m_Add(m_Specific(Op0), m_AllOnes())) && + isKnownToBeAPowerOfTwo(Op0, Q.DL, /*OrZero*/ true, 0, Q.AC, Q.CxtI, Q.DT)) + return Constant::getNullValue(Op0->getType()); + + if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, true)) + return V; + + // Try some generic simplifications for associative operations. + if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, Q, + MaxRecurse)) + return V; + + // And distributes over Or. Try some generic simplifications based on this. + if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or, + Q, MaxRecurse)) + return V; + + // And distributes over Xor. Try some generic simplifications based on this. + if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor, + Q, MaxRecurse)) + return V; + + // If the operation is with the result of a select instruction, check whether + // operating on either branch of the select always yields the same value. + if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) + if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, Q, + MaxRecurse)) + return V; + + // If the operation is with the result of a phi instruction, check whether + // operating on all incoming values of the phi always yields the same value. + if (isa<PHINode>(Op0) || isa<PHINode>(Op1)) + if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, Q, + MaxRecurse)) + return V; + + // Assuming the effective width of Y is not larger than A, i.e. all bits + // from X and Y are disjoint in (X << A) | Y, + // if the mask of this AND op covers all bits of X or Y, while it covers + // no bits from the other, we can bypass this AND op. E.g., + // ((X << A) | Y) & Mask -> Y, + // if Mask = ((1 << effective_width_of(Y)) - 1) + // ((X << A) | Y) & Mask -> X << A, + // if Mask = ((1 << effective_width_of(X)) - 1) << A + // SimplifyDemandedBits in InstCombine can optimize the general case. + // This pattern aims to help other passes for a common case. + Value *Y, *XShifted; + if (match(Op1, m_APInt(Mask)) && + match(Op0, m_c_Or(m_CombineAnd(m_NUWShl(m_Value(X), m_APInt(ShAmt)), + m_Value(XShifted)), + m_Value(Y)))) { + const unsigned Width = Op0->getType()->getScalarSizeInBits(); + const unsigned ShftCnt = ShAmt->getLimitedValue(Width); + const KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); + const unsigned EffWidthY = Width - YKnown.countMinLeadingZeros(); + if (EffWidthY <= ShftCnt) { + const KnownBits XKnown = computeKnownBits(X, Q.DL, 0, Q.AC, Q.CxtI, + Q.DT); + const unsigned EffWidthX = Width - XKnown.countMinLeadingZeros(); + const APInt EffBitsY = APInt::getLowBitsSet(Width, EffWidthY); + const APInt EffBitsX = APInt::getLowBitsSet(Width, EffWidthX) << ShftCnt; + // If the mask is extracting all bits from X or Y as is, we can skip + // this AND op. + if (EffBitsY.isSubsetOf(*Mask) && !EffBitsX.intersects(*Mask)) + return Y; + if (EffBitsX.isSubsetOf(*Mask) && !EffBitsY.intersects(*Mask)) + return XShifted; + } + } + + return nullptr; +} + +Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const SimplifyQuery &Q) { + return ::SimplifyAndInst(Op0, Op1, Q, RecursionLimit); +} + +/// Given operands for an Or, see if we can fold the result. +/// If not, this returns null. +static Value *SimplifyOrInst(Value *Op0, Value *Op1, const SimplifyQuery &Q, + unsigned MaxRecurse) { + if (Constant *C = foldOrCommuteConstant(Instruction::Or, Op0, Op1, Q)) + return C; + + // X | undef -> -1 + // X | -1 = -1 + // Do not return Op1 because it may contain undef elements if it's a vector. + if (match(Op1, m_Undef()) || 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(Op1), m_Value())))) + return Constant::getAllOnesValue(Op0->getType()); + + Value *A, *B; + // (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; + + // (~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; + + if (Value *V = simplifyAndOrOfCmps(Q, Op0, Op1, false)) + return V; + + // If we have a multiplication overflow check that is being 'and'ed with a + // check that one of the multipliers is not zero, we can omit the 'and', and + // only keep the overflow check. + if (Value *V = omitCheckForZeroBeforeInvertedMulWithOverflow(Op0, Op1)) + return V; + if (Value *V = omitCheckForZeroBeforeInvertedMulWithOverflow(Op1, Op0)) + return V; + + // Try some generic simplifications for associative operations. + if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, Q, + MaxRecurse)) + return V; + + // Or distributes over And. Try some generic simplifications based on this. + if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And, Q, + MaxRecurse)) + return V; + + // If the operation is with the result of a select instruction, check whether + // operating on either branch of the select always yields the same value. + if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)) + if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, Q, + MaxRecurse)) + return V; + + // (A & 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 (match(Op1, m_Undef())) + return Op1; + + // A ^ 0 = A + if (match(Op1, m_Zero())) + return Op0; + + // A ^ A = 0 + if (Op0 == Op1) + return Constant::getNullValue(Op0->getType()); + + // A ^ ~A = ~A ^ A = -1 + if (match(Op0, m_Not(m_Specific(Op1))) || + match(Op1, m_Not(m_Specific(Op0)))) + return Constant::getAllOnesValue(Op0->getType()); + + // Try some generic simplifications for associative operations. + if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, Q, + MaxRecurse)) + return V; + + // Threading Xor over selects and phi nodes is pointless, so don't bother. + // Threading over the select in "A ^ select(cond, B, C)" means evaluating + // "A^B" and "A^C" and seeing if they are equal; but they are equal if and + // only if B and C are equal. If B and C are equal then (since we assume + // that operands have already been simplified) "select(cond, B, C)" should + // have been simplified to the common value of B and C already. Analysing + // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly + // for threading over phi nodes. + + return nullptr; +} + +Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const 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(const DataLayout &DL, const TargetLibraryInfo *TLI, + const DominatorTree *DT, CmpInst::Predicate Pred, + AssumptionCache *AC, const Instruction *CxtI, + const InstrInfoQuery &IIQ, Value *LHS, Value *RHS) { + // First, skip past any trivial no-ops. + LHS = LHS->stripPointerCasts(); + RHS = RHS->stripPointerCasts(); + + // A non-null pointer is not equal to a null pointer. + if (llvm::isKnownNonZero(LHS, DL, 0, nullptr, nullptr, nullptr, + IIQ.UseInstrInfo) && + isa<ConstantPointerNull>(RHS) && + (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE)) + return ConstantInt::get(GetCompareTy(LHS), + !CmpInst::isTrueWhenEqual(Pred)); + + // We can only fold certain predicates on pointer comparisons. + switch (Pred) { + default: + return nullptr; + + // Equality comaprisons are easy to fold. + case CmpInst::ICMP_EQ: + case CmpInst::ICMP_NE: + break; + + // We can only handle unsigned relational comparisons because 'inbounds' on + // a GEP only protects against unsigned wrapping. + case CmpInst::ICMP_UGT: + case CmpInst::ICMP_UGE: + case CmpInst::ICMP_ULT: + case CmpInst::ICMP_ULE: + // However, we have to switch them to their signed variants to handle + // negative indices from the base pointer. + Pred = ICmpInst::getSignedPredicate(Pred); + break; + } + + // Strip off any constant offsets so that we can reason about them. + // It's tempting to use getUnderlyingObject or even just stripInBoundsOffsets + // here and compare base addresses like AliasAnalysis does, however there are + // numerous hazards. AliasAnalysis and its utilities rely on special rules + // governing loads and stores which don't apply to icmps. Also, AliasAnalysis + // doesn't need to guarantee pointer inequality when it says NoAlias. + Constant *LHSOffset = stripAndComputeConstantOffsets(DL, LHS); + Constant *RHSOffset = stripAndComputeConstantOffsets(DL, RHS); + + // If LHS and RHS are related via constant offsets to the same base + // value, we can replace it with an icmp which just compares the offsets. + if (LHS == RHS) + return ConstantExpr::getICmp(Pred, LHSOffset, RHSOffset); + + // Various optimizations for (in)equality comparisons. + if (Pred == CmpInst::ICMP_EQ || Pred == CmpInst::ICMP_NE) { + // Different non-empty allocations that exist at the same time have + // different addresses (if the program can tell). Global variables always + // exist, so they always exist during the lifetime of each other and all + // allocas. Two different allocas usually have different addresses... + // + // However, if there's an @llvm.stackrestore dynamically in between two + // allocas, they may have the same address. It's tempting to reduce the + // scope of the problem by only looking at *static* allocas here. That would + // cover the majority of allocas while significantly reducing the likelihood + // of having an @llvm.stackrestore pop up in the middle. However, it's not + // actually impossible for an @llvm.stackrestore to pop up in the middle of + // an entry block. Also, if we have a block that's not attached to a + // function, we can't tell if it's "static" under the current definition. + // Theoretically, this problem could be fixed by creating a new kind of + // instruction kind specifically for static allocas. Such a new instruction + // could be required to be at the top of the entry block, thus preventing it + // from being subject to a @llvm.stackrestore. Instcombine could even + // convert regular allocas into these special allocas. It'd be nifty. + // However, until then, this problem remains open. + // + // So, we'll assume that two non-empty allocas have different addresses + // for now. + // + // With all that, if the offsets are within the bounds of their allocations + // (and not one-past-the-end! so we can't use inbounds!), and their + // allocations aren't the same, the pointers are not equal. + // + // Note that it's not necessary to check for LHS being a global variable + // address, due to canonicalization and constant folding. + if (isa<AllocaInst>(LHS) && + (isa<AllocaInst>(RHS) || isa<GlobalVariable>(RHS))) { + ConstantInt *LHSOffsetCI = dyn_cast<ConstantInt>(LHSOffset); + ConstantInt *RHSOffsetCI = dyn_cast<ConstantInt>(RHSOffset); + uint64_t LHSSize, RHSSize; + 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, DL); + GetUnderlyingObjects(RHS, RHSUObjs, DL); + + // 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_APInt(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); + } + + return nullptr; +} + +/// 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) { + Type *ITy = GetCompareTy(LHS); // The return type. + + 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. + if (A && C && (A == C || A == D || B == C || B == D) && NoLHSWrapProblem && + NoRHSWrapProblem) { + // Determine Y and Z in the form icmp (X+Y), (X+Z). + Value *Y, *Z; + if (A == C) { + // C + B == C + D -> B == D + Y = B; + Z = D; + } else if (A == D) { + // D + B == C + D -> B == C + Y = B; + Z = C; + } else if (B == C) { + // A + C == C + D -> A == D + Y = A; + Z = D; + } else { + assert(B == D); + // A + D == C + D -> A == C + Y = A; + Z = C; + } + if (Value *V = SimplifyICmpInst(Pred, Y, Z, Q, MaxRecurse - 1)) + return V; + } + } + + { + Value *Y = nullptr; + // icmp pred (or X, Y), X + if (LBO && match(LBO, m_c_Or(m_Value(Y), m_Specific(RHS)))) { + if (Pred == ICmpInst::ICMP_ULT) + return getFalse(ITy); + if (Pred == ICmpInst::ICMP_UGE) + return getTrue(ITy); + + if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGE) { + 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 X, (or X, Y) + if (RBO && match(RBO, m_c_Or(m_Value(Y), m_Specific(LHS)))) { + if (Pred == ICmpInst::ICMP_ULE) + return getTrue(ITy); + if (Pred == ICmpInst::ICMP_UGT) + return getFalse(ITy); + + if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SLE) { + KnownBits LHSKnown = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); + KnownBits YKnown = computeKnownBits(Y, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); + if (LHSKnown.isNonNegative() && YKnown.isNegative()) + return Pred == ICmpInst::ICMP_SGT ? getTrue(ITy) : getFalse(ITy); + if (LHSKnown.isNegative() || YKnown.isNonNegative()) + return Pred == ICmpInst::ICMP_SGT ? getFalse(ITy) : getTrue(ITy); + } + } + } + + // icmp pred (and X, Y), X + if (LBO && 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 X, (and X, Y) + if (RBO && match(RBO, m_c_And(m_Value(), m_Specific(LHS)))) { + if (Pred == ICmpInst::ICMP_UGE) + return getTrue(ITy); + if (Pred == ICmpInst::ICMP_ULT) + return getFalse(ITy); + } + + // 0 - (zext X) pred C + if (!CmpInst::isUnsigned(Pred) && match(LHS, m_Neg(m_ZExt(m_Value())))) { + if (ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS)) { + if (RHSC->getValue().isStrictlyPositive()) { + if (Pred == ICmpInst::ICMP_SLT) + return ConstantInt::getTrue(RHSC->getContext()); + if (Pred == ICmpInst::ICMP_SGE) + return ConstantInt::getFalse(RHSC->getContext()); + if (Pred == ICmpInst::ICMP_EQ) + return ConstantInt::getFalse(RHSC->getContext()); + if (Pred == ICmpInst::ICMP_NE) + return ConstantInt::getTrue(RHSC->getContext()); + } + if (RHSC->getValue().isNonNegative()) { + if (Pred == ICmpInst::ICMP_SLE) + return ConstantInt::getTrue(RHSC->getContext()); + if (Pred == ICmpInst::ICMP_SGT) + return ConstantInt::getFalse(RHSC->getContext()); + } + } + } + + // icmp pred (urem X, Y), Y + if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) { + 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 X, (urem Y, X) + if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) { + switch (Pred) { + default: + break; + case ICmpInst::ICMP_SGT: + case ICmpInst::ICMP_SGE: { + KnownBits Known = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); + if (!Known.isNonNegative()) + break; + LLVM_FALLTHROUGH; + } + case ICmpInst::ICMP_NE: + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_UGE: + return getTrue(ITy); + case ICmpInst::ICMP_SLT: + case ICmpInst::ICMP_SLE: { + KnownBits Known = computeKnownBits(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT); + if (!Known.isNonNegative()) + break; + LLVM_FALLTHROUGH; + } + case ICmpInst::ICMP_EQ: + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_ULE: + return getFalse(ITy); + } + } + + // x >> y <=u x + // x udiv y <=u x. + if (LBO && (match(LBO, m_LShr(m_Specific(RHS), m_Value())) || + match(LBO, m_UDiv(m_Specific(RHS), m_Value())))) { + // icmp pred (X op Y), X + if (Pred == ICmpInst::ICMP_UGT) + return getFalse(ITy); + if (Pred == ICmpInst::ICMP_ULE) + return getTrue(ITy); + } + + // x >=u x >> y + // x >=u x udiv y. + if (RBO && (match(RBO, m_LShr(m_Specific(LHS), m_Value())) || + match(RBO, m_UDiv(m_Specific(LHS), m_Value())))) { + // icmp pred X, (X op Y) + if (Pred == ICmpInst::ICMP_ULT) + return getFalse(ITy); + if (Pred == ICmpInst::ICMP_UGE) + return getTrue(ITy); + } + + // handle: + // CI2 << X == CI + // CI2 << X != CI + // + // where CI2 is a power of 2 and CI isn't + if (auto *CI = dyn_cast<ConstantInt>(RHS)) { + const APInt *CI2Val, *CIVal = &CI->getValue(); + if (LBO && match(LBO, m_Shl(m_APInt(CI2Val), m_Value())) && + CI2Val->isPowerOf2()) { + if (!CIVal->isPowerOf2()) { + // CI2 << X can equal zero in some circumstances, + // this simplification is unsafe if CI is zero. + // + // We know it is safe if: + // - The shift is nsw, we can't shift out the one bit. + // - The shift is nuw, we can't shift out the one bit. + // - CI2 is one + // - CI isn't zero + if (Q.IIQ.hasNoSignedWrap(cast<OverflowingBinaryOperator>(LBO)) || + Q.IIQ.hasNoUnsignedWrap(cast<OverflowingBinaryOperator>(LBO)) || + CI2Val->isOneValue() || !CI->isZero()) { + if (Pred == ICmpInst::ICMP_EQ) + return ConstantInt::getFalse(RHS->getContext()); + if (Pred == ICmpInst::ICMP_NE) + return ConstantInt::getTrue(RHS->getContext()); + } + } + if (CIVal->isSignMask() && CI2Val->isOneValue()) { + if (Pred == ICmpInst::ICMP_UGT) + return ConstantInt::getFalse(RHS->getContext()); + if (Pred == ICmpInst::ICMP_ULE) + return ConstantInt::getTrue(RHS->getContext()); + } + } + } + + if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() && + LBO->getOperand(1) == RBO->getOperand(1)) { + switch (LBO->getOpcode()) { + default: + break; + case Instruction::UDiv: + case Instruction::LShr: + if (ICmpInst::isSigned(Pred) || !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: + // Always true. + return getTrue(ITy); + case CmpInst::ICMP_ULT: + // Always false. + return getFalse(ITy); + } + } + + // Variants on "max(x,y) >= min(x,z)". + Value *C, *D; + if (match(LHS, m_SMax(m_Value(A), m_Value(B))) && + match(RHS, m_SMin(m_Value(C), m_Value(D))) && + (A == C || A == D || B == C || B == D)) { + // max(x, ?) pred min(x, ?). + if (Pred == CmpInst::ICMP_SGE) + // Always true. + return getTrue(ITy); + if (Pred == CmpInst::ICMP_SLT) + // Always false. + return getFalse(ITy); + } else if (match(LHS, m_SMin(m_Value(A), m_Value(B))) && + match(RHS, m_SMax(m_Value(C), m_Value(D))) && + (A == C || A == D || B == C || B == D)) { + // min(x, ?) pred max(x, ?). + if (Pred == CmpInst::ICMP_SLE) + // Always true. + return getTrue(ITy); + if (Pred == CmpInst::ICMP_SGT) + // Always false. + return getFalse(ITy); + } else if (match(LHS, m_UMax(m_Value(A), m_Value(B))) && + match(RHS, m_UMin(m_Value(C), m_Value(D))) && + (A == C || A == D || B == C || B == D)) { + // max(x, ?) pred min(x, ?). + if (Pred == CmpInst::ICMP_UGE) + // Always true. + return getTrue(ITy); + if (Pred == CmpInst::ICMP_ULT) + // Always false. + return getFalse(ITy); + } else if (match(LHS, m_UMin(m_Value(A), m_Value(B))) && + match(RHS, m_UMax(m_Value(C), m_Value(D))) && + (A == C || A == D || B == C || B == D)) { + // min(x, ?) pred max(x, ?). + if (Pred == CmpInst::ICMP_ULE) + // Always true. + return getTrue(ITy); + if (Pred == CmpInst::ICMP_UGT) + // Always false. + return getFalse(ITy); + } + + return nullptr; +} + +/// Given operands for an ICmpInst, see if we can fold the result. +/// If not, this returns null. +static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const SimplifyQuery &Q, unsigned MaxRecurse) { + CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; + assert(CmpInst::isIntPredicate(Pred) && "Not an integer compare!"); + + if (Constant *CLHS = dyn_cast<Constant>(LHS)) { + if (Constant *CRHS = dyn_cast<Constant>(RHS)) + return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI); + + // If we have a constant, make sure it is on the RHS. + std::swap(LHS, RHS); + Pred = CmpInst::getSwappedPredicate(Pred); + } + assert(!isa<UndefValue>(LHS) && "Unexpected icmp undef,%X"); + + Type *ITy = GetCompareTy(LHS); // The return type. + + // For EQ and NE, we can always pick a value for the undef to make the + // predicate pass or fail, so we can return undef. + // Matches behavior in llvm::ConstantFoldCompareInstruction. + if (isa<UndefValue>(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 || isa<UndefValue>(RHS)) + return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); + + if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q)) + return V; + + if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q)) + return V; + + if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS, Q.IIQ)) + return V; + + // If both operands have range metadata, use the metadata + // to simplify the comparison. + if (isa<Instruction>(RHS) && isa<Instruction>(LHS)) { + auto RHS_Instr = cast<Instruction>(RHS); + auto LHS_Instr = cast<Instruction>(LHS); + + if (Q.IIQ.getMetadata(RHS_Instr, LLVMContext::MD_range) && + Q.IIQ.getMetadata(LHS_Instr, LLVMContext::MD_range)) { + auto RHS_CR = getConstantRangeFromMetadata( + *RHS_Instr->getMetadata(LLVMContext::MD_range)); + auto LHS_CR = getConstantRangeFromMetadata( + *LHS_Instr->getMetadata(LLVMContext::MD_range)); + + auto Satisfied_CR = ConstantRange::makeSatisfyingICmpRegion(Pred, RHS_CR); + if (Satisfied_CR.contains(LHS_CR)) + return ConstantInt::getTrue(RHS->getContext()); + + auto InversedSatisfied_CR = ConstantRange::makeSatisfyingICmpRegion( + CmpInst::getInversePredicate(Pred), RHS_CR); + if (InversedSatisfied_CR.contains(LHS_CR)) + return ConstantInt::getFalse(RHS->getContext()); + } + } + + // Compare of cast, for example (zext X) != 0 -> X != 0 + if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) { + Instruction *LI = cast<CastInst>(LHS); + Value *SrcOp = LI->getOperand(0); + Type *SrcTy = SrcOp->getType(); + Type *DstTy = LI->getType(); + + // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input + // if the integer type is the same size as the pointer type. + if (MaxRecurse && isa<PtrToIntInst>(LI) && + Q.DL.getTypeSizeInBits(SrcTy) == DstTy->getPrimitiveSizeInBits()) { + if (Constant *RHSC = dyn_cast<Constant>(RHS)) { + // Transfer the cast to the constant. + if (Value *V = SimplifyICmpInst(Pred, SrcOp, + ConstantExpr::getIntToPtr(RHSC, SrcTy), + Q, MaxRecurse-1)) + return V; + } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) { + if (RI->getOperand(0)->getType() == SrcTy) + // Compare without the cast. + if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), + Q, MaxRecurse-1)) + return V; + } + } + + if (isa<ZExtInst>(LHS)) { + // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the + // same type. + if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) { + if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) + // Compare X and Y. Note that signed predicates become unsigned. + if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), + SrcOp, RI->getOperand(0), Q, + MaxRecurse-1)) + return V; + } + // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended + // too. If not, then try to deduce the result of the comparison. + else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { + // Compute the constant that would happen if we truncated to SrcTy then + // reextended to DstTy. + Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); + Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy); + + // If the re-extended constant didn't change then this is effectively + // also a case of comparing two zero-extended values. + if (RExt == CI && MaxRecurse) + if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred), + SrcOp, Trunc, Q, MaxRecurse-1)) + return V; + + // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit + // there. Use this to work out the result of the comparison. + if (RExt != CI) { + switch (Pred) { + default: llvm_unreachable("Unknown ICmp predicate!"); + // LHS <u RHS. + case ICmpInst::ICMP_EQ: + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_UGE: + return ConstantInt::getFalse(CI->getContext()); + + case ICmpInst::ICMP_NE: + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_ULE: + return ConstantInt::getTrue(CI->getContext()); + + // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS + // is non-negative then LHS <s RHS. + case ICmpInst::ICMP_SGT: + case ICmpInst::ICMP_SGE: + return CI->getValue().isNegative() ? + ConstantInt::getTrue(CI->getContext()) : + ConstantInt::getFalse(CI->getContext()); + + case ICmpInst::ICMP_SLT: + case ICmpInst::ICMP_SLE: + return CI->getValue().isNegative() ? + ConstantInt::getFalse(CI->getContext()) : + ConstantInt::getTrue(CI->getContext()); + } + } + } + } + + if (isa<SExtInst>(LHS)) { + // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the + // same type. + if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) { + if (MaxRecurse && SrcTy == RI->getOperand(0)->getType()) + // Compare X and Y. Note that the predicate does not change. + if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0), + Q, MaxRecurse-1)) + return V; + } + // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended + // too. If not, then try to deduce the result of the comparison. + else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) { + // Compute the constant that would happen if we truncated to SrcTy then + // reextended to DstTy. + Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy); + Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy); + + // If the re-extended constant didn't change then this is effectively + // also a case of comparing two sign-extended values. + if (RExt == CI && MaxRecurse) + if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, Q, MaxRecurse-1)) + return V; + + // Otherwise the upper bits of LHS are all equal, while RHS has varying + // bits there. Use this to work out the result of the comparison. + if (RExt != CI) { + switch (Pred) { + default: llvm_unreachable("Unknown ICmp predicate!"); + case ICmpInst::ICMP_EQ: + return ConstantInt::getFalse(CI->getContext()); + case ICmpInst::ICMP_NE: + return ConstantInt::getTrue(CI->getContext()); + + // If RHS is non-negative then LHS <s RHS. If RHS is negative then + // LHS >s RHS. + case ICmpInst::ICMP_SGT: + case ICmpInst::ICMP_SGE: + return CI->getValue().isNegative() ? + ConstantInt::getTrue(CI->getContext()) : + ConstantInt::getFalse(CI->getContext()); + case ICmpInst::ICMP_SLT: + case ICmpInst::ICMP_SLE: + return CI->getValue().isNegative() ? + ConstantInt::getFalse(CI->getContext()) : + ConstantInt::getTrue(CI->getContext()); + + // If LHS is non-negative then LHS <u RHS. If LHS is negative then + // LHS >u RHS. + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_UGE: + // Comparison is true iff the LHS <s 0. + if (MaxRecurse) + if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp, + Constant::getNullValue(SrcTy), + Q, MaxRecurse-1)) + return V; + break; + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_ULE: + // Comparison is true iff the LHS >=s 0. + if (MaxRecurse) + if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp, + Constant::getNullValue(SrcTy), + Q, MaxRecurse-1)) + return V; + break; + } + } + } + } + } + + // icmp eq|ne X, Y -> false|true if X != Y + if (ICmpInst::isEquality(Pred) && + isKnownNonEqual(LHS, RHS, Q.DL, Q.AC, Q.CxtI, Q.DT, Q.IIQ.UseInstrInfo)) { + return Pred == ICmpInst::ICMP_NE ? getTrue(ITy) : getFalse(ITy); + } + + if (Value *V = simplifyICmpWithBinOp(Pred, LHS, RHS, Q, MaxRecurse)) + return V; + + if (Value *V = simplifyICmpWithMinMax(Pred, LHS, RHS, Q, MaxRecurse)) + return V; + + // Simplify comparisons of related pointers using a powerful, recursive + // GEP-walk when we have target data available.. + if (LHS->getType()->isPointerTy()) + if (auto *C = computePointerICmp(Q.DL, Q.TLI, Q.DT, Pred, Q.AC, Q.CxtI, + Q.IIQ, LHS, RHS)) + 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(Q.DL, Q.TLI, Q.DT, Pred, Q.AC, Q.CxtI, + Q.IIQ, CLHS->getPointerOperand(), + CRHS->getPointerOperand())) + return C; + + if (GetElementPtrInst *GLHS = dyn_cast<GetElementPtrInst>(LHS)) { + if (GEPOperator *GRHS = dyn_cast<GEPOperator>(RHS)) { + if (GLHS->getPointerOperand() == GRHS->getPointerOperand() && + GLHS->hasAllConstantIndices() && GRHS->hasAllConstantIndices() && + (ICmpInst::isEquality(Pred) || + (GLHS->isInBounds() && GRHS->isInBounds() && + Pred == ICmpInst::getSignedPredicate(Pred)))) { + // The bases are equal and the indices are constant. Build a constant + // expression GEP with the same indices and a null base pointer to see + // what constant folding can make out of it. + Constant *Null = Constant::getNullValue(GLHS->getPointerOperandType()); + SmallVector<Value *, 4> IndicesLHS(GLHS->idx_begin(), GLHS->idx_end()); + Constant *NewLHS = ConstantExpr::getGetElementPtr( + GLHS->getSourceElementType(), Null, IndicesLHS); + + SmallVector<Value *, 4> IndicesRHS(GRHS->idx_begin(), GRHS->idx_end()); + Constant *NewRHS = ConstantExpr::getGetElementPtr( + GLHS->getSourceElementType(), Null, IndicesRHS); + return ConstantExpr::getICmp(Pred, NewLHS, NewRHS); + } + } + } + + // If the comparison is with the result of a select instruction, check whether + // comparing with either branch of the select always yields the same value. + if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)) + if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, Q, MaxRecurse)) + return V; + + // If the comparison is with the result of a phi instruction, check whether + // doing the compare with each incoming phi value yields a common result. + if (isa<PHINode>(LHS) || isa<PHINode>(RHS)) + if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, Q, MaxRecurse)) + return V; + + return nullptr; +} + +Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const SimplifyQuery &Q) { + return ::SimplifyICmpInst(Predicate, LHS, RHS, Q, RecursionLimit); +} + +/// Given operands for an FCmpInst, see if we can fold the result. +/// If not, this returns null. +static Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS, + FastMathFlags FMF, const SimplifyQuery &Q, + unsigned MaxRecurse) { + CmpInst::Predicate Pred = (CmpInst::Predicate)Predicate; + assert(CmpInst::isFPPredicate(Pred) && "Not an FP compare!"); + + if (Constant *CLHS = dyn_cast<Constant>(LHS)) { + if (Constant *CRHS = dyn_cast<Constant>(RHS)) + return ConstantFoldCompareInstOperands(Pred, CLHS, CRHS, Q.DL, Q.TLI); + + // If we have a constant, make sure it is on the RHS. + std::swap(LHS, RHS); + Pred = CmpInst::getSwappedPredicate(Pred); + } + + // Fold trivial predicates. + Type *RetTy = GetCompareTy(LHS); + if (Pred == FCmpInst::FCMP_FALSE) + return getFalse(RetTy); + if (Pred == FCmpInst::FCMP_TRUE) + return getTrue(RetTy); + + // Fold (un)ordered comparison if we can determine there are no NaNs. + if (Pred == FCmpInst::FCMP_UNO || Pred == FCmpInst::FCMP_ORD) + if (FMF.noNaNs() || + (isKnownNeverNaN(LHS, Q.TLI) && isKnownNeverNaN(RHS, Q.TLI))) + return ConstantInt::get(RetTy, Pred == FCmpInst::FCMP_ORD); + + // NaN is unordered; NaN is not ordered. + assert((FCmpInst::isOrdered(Pred) || FCmpInst::isUnordered(Pred)) && + "Comparison must be either ordered or unordered"); + if (match(RHS, m_NaN())) + return ConstantInt::get(RetTy, CmpInst::isUnordered(Pred)); + + // fcmp pred x, undef and fcmp pred undef, x + // fold to true if unordered, false if ordered + if (isa<UndefValue>(LHS) || isa<UndefValue>(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; + } + } + } + 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->compare(*C) == APFloat::cmpLessThan) || + (match(LHS, m_Intrinsic<Intrinsic::maxnum>(m_Value(), m_APFloat(C2))) && + C2->compare(*C) == APFloat::cmpGreaterThan)) { + 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); +} + +/// See if V simplifies when its operand Op is replaced with RepOp. +static const Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, + const SimplifyQuery &Q, + unsigned MaxRecurse) { + // Trivial replacement. + if (V == Op) + return RepOp; + + // We cannot replace a constant, and shouldn't even try. + if (isa<Constant>(Op)) + return nullptr; + + auto *I = dyn_cast<Instruction>(V); + if (!I) + return nullptr; + + // If this is a binary operator, try to simplify it with the replaced op. + if (auto *B = dyn_cast<BinaryOperator>(I)) { + // Consider: + // %cmp = icmp eq i32 %x, 2147483647 + // %add = add nsw i32 %x, 1 + // %sel = select i1 %cmp, i32 -2147483648, i32 %add + // + // We can't replace %sel with %add unless we strip away the flags. + // TODO: This is an unusual limitation because better analysis results in + // worse simplification. InstCombine can do this fold more generally + // by dropping the flags. Remove this fold to save compile-time? + if (isa<OverflowingBinaryOperator>(B)) + if (Q.IIQ.hasNoSignedWrap(B) || Q.IIQ.hasNoUnsignedWrap(B)) + return nullptr; + if (isa<PossiblyExactOperator>(B) && Q.IIQ.isExact(B)) + return nullptr; + + if (MaxRecurse) { + if (B->getOperand(0) == Op) + return SimplifyBinOp(B->getOpcode(), RepOp, B->getOperand(1), Q, + MaxRecurse - 1); + if (B->getOperand(1) == Op) + return SimplifyBinOp(B->getOpcode(), B->getOperand(0), RepOp, Q, + MaxRecurse - 1); + } + } + + // Same for CmpInsts. + if (CmpInst *C = dyn_cast<CmpInst>(I)) { + if (MaxRecurse) { + if (C->getOperand(0) == Op) + return SimplifyCmpInst(C->getPredicate(), RepOp, C->getOperand(1), Q, + MaxRecurse - 1); + if (C->getOperand(1) == Op) + return SimplifyCmpInst(C->getPredicate(), C->getOperand(0), RepOp, Q, + MaxRecurse - 1); + } + } + + // Same for GEPs. + if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) { + if (MaxRecurse) { + SmallVector<Value *, 8> NewOps(GEP->getNumOperands()); + transform(GEP->operands(), NewOps.begin(), + [&](Value *V) { return V == Op ? RepOp : V; }); + return SimplifyGEPInst(GEP->getSourceElementType(), NewOps, Q, + MaxRecurse - 1); + } + } + + // TODO: We could hand off more cases to instsimplify here. + + // If all operands are constant after substituting Op for RepOp then we can + // constant fold the instruction. + if (Constant *CRepOp = dyn_cast<Constant>(RepOp)) { + // Build a list of all constant operands. + SmallVector<Constant *, 8> ConstOps; + for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) { + if (I->getOperand(i) == Op) + ConstOps.push_back(CRepOp); + else if (Constant *COp = dyn_cast<Constant>(I->getOperand(i))) + ConstOps.push_back(COp); + else + break; + } + + // All operands were constants, fold it. + if (ConstOps.size() == I->getNumOperands()) { + if (CmpInst *C = dyn_cast<CmpInst>(I)) + return ConstantFoldCompareInstOperands(C->getPredicate(), ConstOps[0], + ConstOps[1], Q.DL, Q.TLI); + + if (LoadInst *LI = dyn_cast<LoadInst>(I)) + if (!LI->isVolatile()) + return ConstantFoldLoadFromConstPtr(ConstOps[0], LI->getType(), Q.DL); + + return ConstantFoldInstOperands(I, ConstOps, Q.DL, Q.TLI); + } + } + + return nullptr; +} + +/// 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; + + if (ICmpInst::isEquality(Pred) && 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, + Pred == ICmpInst::ICMP_EQ)) + return V; + + // Test for a bogus zero-shift-guard-op around funnel-shift or rotate. + Value *ShAmt; + auto isFsh = m_CombineOr(m_Intrinsic<Intrinsic::fshl>(m_Value(X), m_Value(), + m_Value(ShAmt)), + m_Intrinsic<Intrinsic::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 && + Pred == ICmpInst::ICMP_EQ) + return X; + // (ShAmt != 0) ? X : fshl(X, *, ShAmt) --> X + // (ShAmt != 0) ? X : fshr(*, X, ShAmt) --> X + if (match(FalseVal, isFsh) && TrueVal == X && CmpLHS == ShAmt && + Pred == ICmpInst::ICMP_NE) + 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_Intrinsic<Intrinsic::fshl>(m_Value(X), + m_Deferred(X), + m_Value(ShAmt)), + m_Intrinsic<Intrinsic::fshr>(m_Value(X), + m_Deferred(X), + m_Value(ShAmt))); + // (ShAmt != 0) ? fshl(X, X, ShAmt) : X --> fshl(X, X, ShAmt) + // (ShAmt != 0) ? fshr(X, X, ShAmt) : X --> fshr(X, X, ShAmt) + if (match(TrueVal, isRotate) && FalseVal == X && CmpLHS == ShAmt && + Pred == ICmpInst::ICMP_NE) + return TrueVal; + // (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; + } + + // Check for other compares that behave like bit test. + if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred, + TrueVal, FalseVal)) + return V; + + // If we have an equality comparison, then we know the value in one of the + // arms of the select. See if substituting this value into the arm and + // simplifying the result yields the same value as the other arm. + if (Pred == ICmpInst::ICMP_EQ) { + if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) == + TrueVal || + SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) == + TrueVal) + return FalseVal; + if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) == + FalseVal || + SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) == + FalseVal) + return FalseVal; + } else if (Pred == ICmpInst::ICMP_NE) { + if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q, MaxRecurse) == + FalseVal || + SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q, MaxRecurse) == + FalseVal) + return TrueVal; + if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q, MaxRecurse) == + TrueVal || + SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q, MaxRecurse) == + TrueVal) + return TrueVal; + } + + return nullptr; +} + +/// Try to simplify a select instruction when its condition operand is a +/// floating-point comparison. +static Value *simplifySelectWithFCmp(Value *Cond, Value *T, Value *F) { + 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; + + // TODO: The transform may not be valid with -0.0. An incomplete way of + // testing for that possibility is to check if at least one operand is a + // non-zero constant. + const APFloat *C; + if ((match(T, m_APFloat(C)) && C->isNonZero()) || + (match(F, m_APFloat(C)) && C->isNonZero())) { + // (T == F) ? T : F --> F + // (F == T) ? T : F --> F + if (Pred == FCmpInst::FCMP_OEQ) + return F; + + // (T != F) ? T : F --> T + // (F != T) ? T : F --> T + if (Pred == FCmpInst::FCMP_UNE) + return T; + } + + return nullptr; +} + +/// Given operands for a SelectInst, see if we can fold the result. +/// If not, this returns null. +static Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, + const SimplifyQuery &Q, unsigned MaxRecurse) { + if (auto *CondC = dyn_cast<Constant>(Cond)) { + if (auto *TrueC = dyn_cast<Constant>(TrueVal)) + if (auto *FalseC = dyn_cast<Constant>(FalseVal)) + return ConstantFoldSelectInstruction(CondC, TrueC, FalseC); + + // select undef, X, Y -> X or Y + if (isa<UndefValue>(CondC)) + return isa<Constant>(FalseVal) ? FalseVal : TrueVal; + + // TODO: Vector constants with undef elements don't simplify. + + // select true, X, Y -> X + if (CondC->isAllOnesValue()) + return TrueVal; + // select false, X, Y -> Y + if (CondC->isNullValue()) + return FalseVal; + } + + // select ?, X, X -> X + if (TrueVal == FalseVal) + return TrueVal; + + if (isa<UndefValue>(TrueVal)) // select ?, undef, X -> X + return FalseVal; + if (isa<UndefValue>(FalseVal)) // select ?, X, undef -> X + return TrueVal; + + if (Value *V = + simplifySelectWithICmpCond(Cond, TrueVal, FalseVal, Q, MaxRecurse)) + return V; + + if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal)) + return V; + + if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal)) + return V; + + Optional<bool> Imp = isImpliedByDomCondition(Cond, Q.CxtI, Q.DL); + if (Imp) + return *Imp ? TrueVal : FalseVal; + + return nullptr; +} + +Value *llvm::SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal, + const SimplifyQuery &Q) { + return ::SimplifySelectInst(Cond, TrueVal, FalseVal, Q, RecursionLimit); +} + +/// Given operands for an GetElementPtrInst, see if we can fold the result. +/// If not, this returns null. +static Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops, + const SimplifyQuery &Q, unsigned) { + // The type of the GEP pointer operand. + unsigned AS = + cast<PointerType>(Ops[0]->getType()->getScalarType())->getAddressSpace(); + + // getelementptr P -> P. + if (Ops.size() == 1) + return Ops[0]; + + // Compute the (pointer) type returned by the GEP instruction. + Type *LastType = GetElementPtrInst::getIndexedType(SrcTy, Ops.slice(1)); + Type *GEPTy = PointerType::get(LastType, AS); + if (VectorType *VT = dyn_cast<VectorType>(Ops[0]->getType())) + GEPTy = VectorType::get(GEPTy, VT->getNumElements()); + else if (VectorType *VT = dyn_cast<VectorType>(Ops[1]->getType())) + GEPTy = VectorType::get(GEPTy, VT->getNumElements()); + + if (isa<UndefValue>(Ops[0])) + return UndefValue::get(GEPTy); + + if (Ops.size() == 2) { + // getelementptr P, 0 -> P. + if (match(Ops[1], m_Zero()) && Ops[0]->getType() == GEPTy) + return Ops[0]; + + Type *Ty = SrcTy; + if (Ty->isSized()) { + Value *P; + uint64_t C; + uint64_t TyAllocSize = Q.DL.getTypeAllocSize(Ty); + // getelementptr P, N -> P if P points to a type of zero size. + if (TyAllocSize == 0 && 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.getIndexSizeInBits(AS)) { + auto PtrToIntOrZero = [GEPTy](Value *P) -> Value * { + if (match(P, m_Zero())) + return Constant::getNullValue(GEPTy); + Value *Temp; + if (match(P, m_PtrToInt(m_Value(Temp)))) + if (Temp->getType() == GEPTy) + return Temp; + return nullptr; + }; + + // getelementptr V, (sub P, V) -> P if P points to a type of size 1. + if (TyAllocSize == 1 && + match(Ops[1], m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))))) + if (Value *R = PtrToIntOrZero(P)) + return R; + + // getelementptr V, (ashr (sub P, V), C) -> Q + // if P points to a type of size 1 << C. + if (match(Ops[1], + m_AShr(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))), + m_ConstantInt(C))) && + TyAllocSize == 1ULL << C) + if (Value *R = PtrToIntOrZero(P)) + return R; + + // getelementptr V, (sdiv (sub P, V), C) -> Q + // if P points to a type of size C. + if (match(Ops[1], + m_SDiv(m_Sub(m_Value(P), m_PtrToInt(m_Specific(Ops[0]))), + m_SpecificInt(TyAllocSize)))) + if (Value *R = PtrToIntOrZero(P)) + return R; + } + } + } + + if (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); + + // gep (gep V, C), (sub 0, V) -> C + if (match(Ops.back(), + m_Sub(m_Zero(), m_PtrToInt(m_Specific(StrippedBasePtr))))) { + 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()))) { + 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)); + if (auto *CEFolded = ConstantFoldConstant(CE, Q.DL)) + return CEFolded; + return CE; +} + +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 (match(Val, m_Undef())) + return Agg; + + // insertvalue x, (extractvalue y, n), n + if (ExtractValueInst *EV = dyn_cast<ExtractValueInst>(Val)) + if (EV->getAggregateOperand()->getType() == Agg->getType() && + EV->getIndices() == Idxs) { + // insertvalue undef, (extractvalue y, n), n -> y + if (match(Agg, m_Undef())) + return EV->getAggregateOperand(); + + // insertvalue y, (extractvalue y, n), n -> y + if (Agg == EV->getAggregateOperand()) + return Agg; + } + + return nullptr; +} + +Value *llvm::SimplifyInsertValueInst(Value *Agg, Value *Val, + ArrayRef<unsigned> Idxs, + const 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 ConstantFoldInsertElementInstruction(VecC, ValC, IdxC); + + // Fold into undef if index is out of bounds. + if (auto *CI = dyn_cast<ConstantInt>(Idx)) { + uint64_t NumElements = cast<VectorType>(Vec->getType())->getNumElements(); + if (CI->uge(NumElements)) + return UndefValue::get(Vec->getType()); + } + + // If index is undef, it might be out of bounds (see above case) + if (isa<UndefValue>(Idx)) + return UndefValue::get(Vec->getType()); + + // Inserting an undef scalar? Assume it is the same value as the existing + // vector element. + if (isa<UndefValue>(Val)) + 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_ExtractElement(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 &, + unsigned) { + if (auto *CVec = dyn_cast<Constant>(Vec)) { + if (auto *CIdx = dyn_cast<Constant>(Idx)) + return ConstantFoldExtractElementInstruction(CVec, CIdx); + + // The index is not relevant if our vector is a splat. + if (auto *Splat = CVec->getSplatValue()) + return Splat; + + if (isa<UndefValue>(Vec)) + return UndefValue::get(Vec->getType()->getVectorElementType()); + } + + // If extracting a specified index from the vector, see if we can recursively + // find a previously computed scalar that was inserted into the vector. + if (auto *IdxC = dyn_cast<ConstantInt>(Idx)) { + if (IdxC->getValue().uge(Vec->getType()->getVectorNumElements())) + // definitely out of bounds, thus undefined result + return UndefValue::get(Vec->getType()->getVectorElementType()); + if (Value *Elt = findScalarElement(Vec, IdxC->getZExtValue())) + return Elt; + } + + // An undef extract index can be arbitrarily chosen to be an out-of-range + // index value, which would result in the instruction being undef. + if (isa<UndefValue>(Idx)) + return UndefValue::get(Vec->getType()->getVectorElementType()); + + return nullptr; +} + +Value *llvm::SimplifyExtractElementInst(Value *Vec, Value *Idx, + const SimplifyQuery &Q) { + return ::SimplifyExtractElementInst(Vec, Idx, Q, RecursionLimit); +} + +/// See if we can fold the given phi. If not, returns null. +static Value *SimplifyPHINode(PHINode *PN, const SimplifyQuery &Q) { + // If all of the PHI's incoming values are the same then replace the PHI node + // with the common value. + Value *CommonValue = nullptr; + bool HasUndefInput = false; + for (Value *Incoming : PN->incoming_values()) { + // If the incoming value is the phi node itself, it can safely be skipped. + if (Incoming == PN) continue; + if (isa<UndefValue>(Incoming)) { + // Remember that we saw an undef value, but otherwise ignore them. + HasUndefInput = true; + continue; + } + if (CommonValue && Incoming != CommonValue) + return nullptr; // Not the same, bail out. + CommonValue = Incoming; + } + + // If CommonValue is null then all of the incoming values were either undef or + // equal to the phi node itself. + if (!CommonValue) + return UndefValue::get(PN->getType()); + + // If we have a PHI node like phi(X, undef, X), where X is defined by some + // instruction, we cannot return X as the result of the PHI node unless it + // dominates the PHI block. + if (HasUndefInput) + return valueDominatesPHI(CommonValue, PN, Q.DT) ? CommonValue : nullptr; + + return CommonValue; +} + +static Value *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 = Op0->getType()->getVectorNumElements(); + 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, Constant *Mask, + Type *RetTy, const SimplifyQuery &Q, + unsigned MaxRecurse) { + if (isa<UndefValue>(Mask)) + return UndefValue::get(RetTy); + + Type *InVecTy = Op0->getType(); + unsigned MaskNumElts = Mask->getType()->getVectorNumElements(); + unsigned InVecNumElts = InVecTy->getVectorNumElements(); + + SmallVector<int, 32> Indices; + ShuffleVectorInst::getShuffleMask(Mask, Indices); + assert(MaskNumElts == Indices.size() && + "Size of Indices not same as number of mask elements?"); + + // Canonicalization: If mask does not select elements from an input vector, + // replace that input vector with undef. + bool MaskSelects0 = false, MaskSelects1 = false; + 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 = UndefValue::get(InVecTy); + if (!MaskSelects1) + Op1 = UndefValue::get(InVecTy); + + auto *Op0Const = dyn_cast<Constant>(Op0); + auto *Op1Const = dyn_cast<Constant>(Op1); + + // If all operands are constant, constant fold the shuffle. + if (Op0Const && Op1Const) + return ConstantFoldShuffleVectorInstruction(Op0Const, Op1Const, Mask); + + // Canonicalization: if only one input vector is constant, it shall be the + // second one. + if (Op0Const && !Op1Const) { + std::swap(Op0, Op1); + ShuffleVectorInst::commuteShuffleMask(Indices, InVecNumElts); + } + + // 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 (isa<UndefValue>(Op1) && RetTy == InVecTy && + OpShuf->getMask()->getSplatValue()) + return Op0; + + // 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 (find(Indices, -1) != Indices.end()) + 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, Constant *Mask, + Type *RetTy, const SimplifyQuery &Q) { + return ::SimplifyShuffleVectorInst(Op0, Op1, Mask, RetTy, Q, RecursionLimit); +} + +static Constant *foldConstant(Instruction::UnaryOps Opcode, + Value *&Op, const SimplifyQuery &Q) { + if (auto *C = dyn_cast<Constant>(Op)) + return ConstantFoldUnaryOpOperand(Opcode, C, Q.DL); + return nullptr; +} + +/// Given the operand for an FNeg, see if we can fold the result. If not, this +/// returns null. +static Value *simplifyFNegInst(Value *Op, FastMathFlags FMF, + const SimplifyQuery &Q, unsigned MaxRecurse) { + if (Constant *C = foldConstant(Instruction::FNeg, Op, Q)) + return C; + + Value *X; + // fneg (fneg X) ==> X + if (match(Op, m_FNeg(m_Value(X)))) + return X; + + return nullptr; +} + +Value *llvm::SimplifyFNegInst(Value *Op, FastMathFlags FMF, + const SimplifyQuery &Q) { + return ::simplifyFNegInst(Op, FMF, Q, RecursionLimit); +} + +static Constant *propagateNaN(Constant *In) { + // If the input is a vector with undef elements, just return a default NaN. + if (!In->isNaN()) + return ConstantFP::getNaN(In->getType()); + + // Propagate the existing NaN constant when possible. + // TODO: Should we quiet a signaling NaN? + return In; +} + +/// Perform folds that are common to any floating-point operation. This implies +/// transforms based on undef/NaN because the operation itself makes no +/// difference to the result. +static Constant *simplifyFPOp(ArrayRef<Value *> Ops) { + if (any_of(Ops, [](Value *V) { return isa<UndefValue>(V); })) + return ConstantFP::getNaN(Ops[0]->getType()); + + for (Value *V : Ops) + if (match(V, m_NaN())) + return propagateNaN(cast<Constant>(V)); + + return nullptr; +} + +/// Given operands for an FAdd, see if we can fold the result. If not, this +/// returns null. +static Value *SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q, unsigned MaxRecurse) { + if (Constant *C = foldOrCommuteConstant(Instruction::FAdd, Op0, Op1, Q)) + return C; + + if (Constant *C = simplifyFPOp({Op0, Op1})) + return C; + + // fadd X, -0 ==> X + if (match(Op1, m_NegZeroFP())) + return Op0; + + // fadd X, 0 ==> X, when we know X is not -0 + if (match(Op1, m_PosZeroFP()) && + (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI))) + return Op0; + + // With nnan: -X + X --> 0.0 (and commuted variant) + // We don't have to explicitly exclude infinities (ninf): INF + -INF == NaN. + // Negative zeros are allowed because we always end up with positive zero: + // X = -0.0: (-0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 + // X = -0.0: ( 0.0 - (-0.0)) + (-0.0) == ( 0.0) + (-0.0) == 0.0 + // X = 0.0: (-0.0 - ( 0.0)) + ( 0.0) == (-0.0) + ( 0.0) == 0.0 + // X = 0.0: ( 0.0 - ( 0.0)) + ( 0.0) == ( 0.0) + ( 0.0) == 0.0 + if (FMF.noNaNs()) { + if (match(Op0, m_FSub(m_AnyZeroFP(), m_Specific(Op1))) || + match(Op1, m_FSub(m_AnyZeroFP(), m_Specific(Op0)))) + return ConstantFP::getNullValue(Op0->getType()); + + if (match(Op0, m_FNeg(m_Specific(Op1))) || + match(Op1, m_FNeg(m_Specific(Op0)))) + return ConstantFP::getNullValue(Op0->getType()); + } + + // (X - Y) + Y --> X + // Y + (X - Y) --> X + Value *X; + if (FMF.noSignedZeros() && FMF.allowReassoc() && + (match(Op0, m_FSub(m_Value(X), m_Specific(Op1))) || + match(Op1, m_FSub(m_Value(X), m_Specific(Op0))))) + return X; + + return nullptr; +} + +/// Given operands for an FSub, see if we can fold the result. If not, this +/// returns null. +static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q, unsigned MaxRecurse) { + if (Constant *C = foldOrCommuteConstant(Instruction::FSub, Op0, Op1, Q)) + return C; + + if (Constant *C = simplifyFPOp({Op0, Op1})) + return C; + + // fsub X, +0 ==> X + if (match(Op1, m_PosZeroFP())) + return Op0; + + // fsub X, -0 ==> X, when we know X is not -0 + if (match(Op1, m_NegZeroFP()) && + (FMF.noSignedZeros() || CannotBeNegativeZero(Op0, Q.TLI))) + return Op0; + + // fsub -0.0, (fsub -0.0, X) ==> X + // fsub -0.0, (fneg X) ==> X + Value *X; + if (match(Op0, m_NegZeroFP()) && + match(Op1, m_FNeg(m_Value(X)))) + return X; + + // fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored. + // fsub 0.0, (fneg X) ==> X if signed zeros are ignored. + if (FMF.noSignedZeros() && match(Op0, m_AnyZeroFP()) && + (match(Op1, m_FSub(m_AnyZeroFP(), m_Value(X))) || + match(Op1, m_FNeg(m_Value(X))))) + return X; + + // fsub nnan x, x ==> 0.0 + if (FMF.noNaNs() && Op0 == Op1) + return Constant::getNullValue(Op0->getType()); + + // Y - (Y - X) --> X + // (X + Y) - Y --> X + if (FMF.noSignedZeros() && FMF.allowReassoc() && + (match(Op1, m_FSub(m_Specific(Op0), m_Value(X))) || + match(Op0, m_c_FAdd(m_Specific(Op1), m_Value(X))))) + return X; + + return nullptr; +} + +static Value *SimplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q, unsigned MaxRecurse) { + if (Constant *C = simplifyFPOp({Op0, Op1})) + return C; + + // fmul X, 1.0 ==> X + if (match(Op1, m_FPOne())) + return Op0; + + // fmul 1.0, X ==> X + if (match(Op0, m_FPOne())) + return Op1; + + // fmul nnan nsz X, 0 ==> 0 + if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op1, m_AnyZeroFP())) + return ConstantFP::getNullValue(Op0->getType()); + + // fmul nnan nsz 0, X ==> 0 + if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP())) + return ConstantFP::getNullValue(Op1->getType()); + + // sqrt(X) * sqrt(X) --> X, if we can: + // 1. Remove the intermediate rounding (reassociate). + // 2. Ignore non-zero negative numbers because sqrt would produce NAN. + // 3. Ignore -0.0 because sqrt(-0.0) == -0.0, but -0.0 * -0.0 == 0.0. + Value *X; + if (Op0 == Op1 && match(Op0, m_Intrinsic<Intrinsic::sqrt>(m_Value(X))) && + FMF.allowReassoc() && FMF.noNaNs() && FMF.noSignedZeros()) + return X; + + return nullptr; +} + +/// Given the operands for an FMul, see if we can fold the result +static Value *SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q, unsigned MaxRecurse) { + if (Constant *C = foldOrCommuteConstant(Instruction::FMul, Op0, Op1, Q)) + return C; + + // Now apply simplifications that do not require rounding. + return SimplifyFMAFMul(Op0, Op1, FMF, Q, MaxRecurse); +} + +Value *llvm::SimplifyFAddInst(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q) { + return ::SimplifyFAddInst(Op0, Op1, FMF, Q, RecursionLimit); +} + + +Value *llvm::SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q) { + return ::SimplifyFSubInst(Op0, Op1, FMF, Q, RecursionLimit); +} + +Value *llvm::SimplifyFMulInst(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q) { + return ::SimplifyFMulInst(Op0, Op1, FMF, Q, RecursionLimit); +} + +Value *llvm::SimplifyFMAFMul(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q) { + return ::SimplifyFMAFMul(Op0, Op1, FMF, Q, RecursionLimit); +} + +static Value *SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q, unsigned) { + if (Constant *C = foldOrCommuteConstant(Instruction::FDiv, Op0, Op1, Q)) + return C; + + if (Constant *C = simplifyFPOp({Op0, Op1})) + return C; + + // X / 1.0 -> X + if (match(Op1, m_FPOne())) + return Op0; + + // 0 / X -> 0 + // Requires that NaNs are off (X could be zero) and signed zeroes are + // ignored (X could be positive or negative, so the output sign is unknown). + if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZeroFP())) + return ConstantFP::getNullValue(Op0->getType()); + + if (FMF.noNaNs()) { + // X / X -> 1.0 is legal when NaNs are ignored. + // We can ignore infinities because INF/INF is NaN. + if (Op0 == Op1) + return ConstantFP::get(Op0->getType(), 1.0); + + // (X * Y) / Y --> X if we can reassociate to the above form. + Value *X; + if (FMF.allowReassoc() && match(Op0, m_c_FMul(m_Value(X), m_Specific(Op1)))) + return X; + + // -X / X -> -1.0 and + // X / -X -> -1.0 are legal when NaNs are ignored. + // We can ignore signed zeros because +-0.0/+-0.0 is NaN and ignored. + if (match(Op0, m_FNegNSZ(m_Specific(Op1))) || + match(Op1, m_FNegNSZ(m_Specific(Op0)))) + return ConstantFP::get(Op0->getType(), -1.0); + } + + return nullptr; +} + +Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q) { + return ::SimplifyFDivInst(Op0, Op1, FMF, Q, RecursionLimit); +} + +static Value *SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q, unsigned) { + if (Constant *C = foldOrCommuteConstant(Instruction::FRem, Op0, Op1, Q)) + return C; + + if (Constant *C = simplifyFPOp({Op0, Op1})) + return C; + + // Unlike fdiv, the result of frem always matches the sign of the dividend. + // The constant match may include undef elements in a vector, so return a full + // zero constant as the result. + if (FMF.noNaNs()) { + // +0 % X -> 0 + if (match(Op0, m_PosZeroFP())) + return ConstantFP::getNullValue(Op0->getType()); + // -0 % X -> -0 + if (match(Op0, m_NegZeroFP())) + return ConstantFP::getNegativeZero(Op0->getType()); + } + + return nullptr; +} + +Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, + const SimplifyQuery &Q) { + return ::SimplifyFRemInst(Op0, Op1, FMF, Q, RecursionLimit); +} + +//=== Helper functions for higher up the class hierarchy. + +/// Given the operand for a UnaryOperator, see if we can fold the result. +/// If not, this returns null. +static Value *simplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q, + unsigned MaxRecurse) { + switch (Opcode) { + case Instruction::FNeg: + return simplifyFNegInst(Op, FastMathFlags(), Q, MaxRecurse); + default: + llvm_unreachable("Unexpected opcode"); + } +} + +/// Given the operand for a UnaryOperator, see if we can fold the result. +/// If not, this returns null. +/// Try to use FastMathFlags when folding the result. +static Value *simplifyFPUnOp(unsigned Opcode, Value *Op, + const FastMathFlags &FMF, + const SimplifyQuery &Q, unsigned MaxRecurse) { + switch (Opcode) { + case Instruction::FNeg: + return simplifyFNegInst(Op, FMF, Q, MaxRecurse); + default: + return simplifyUnOp(Opcode, Op, Q, MaxRecurse); + } +} + +Value *llvm::SimplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q) { + return ::simplifyUnOp(Opcode, Op, Q, RecursionLimit); +} + +Value *llvm::SimplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF, + const SimplifyQuery &Q) { + return ::simplifyFPUnOp(Opcode, Op, FMF, Q, RecursionLimit); +} + +/// Given operands for a BinaryOperator, see if we can fold the result. +/// If not, this returns null. +static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, + const SimplifyQuery &Q, unsigned MaxRecurse) { + switch (Opcode) { + case Instruction::Add: + return SimplifyAddInst(LHS, RHS, false, false, Q, MaxRecurse); + case Instruction::Sub: + return SimplifySubInst(LHS, RHS, false, false, Q, MaxRecurse); + case Instruction::Mul: + return SimplifyMulInst(LHS, RHS, Q, MaxRecurse); + case Instruction::SDiv: + return SimplifySDivInst(LHS, RHS, Q, MaxRecurse); + case Instruction::UDiv: + return SimplifyUDivInst(LHS, RHS, Q, MaxRecurse); + case Instruction::SRem: + return SimplifySRemInst(LHS, RHS, Q, MaxRecurse); + case Instruction::URem: + return SimplifyURemInst(LHS, RHS, Q, MaxRecurse); + case Instruction::Shl: + return SimplifyShlInst(LHS, RHS, false, false, Q, MaxRecurse); + case Instruction::LShr: + return SimplifyLShrInst(LHS, RHS, false, Q, MaxRecurse); + case Instruction::AShr: + return SimplifyAShrInst(LHS, RHS, false, Q, MaxRecurse); + case Instruction::And: + return SimplifyAndInst(LHS, RHS, Q, MaxRecurse); + case Instruction::Or: + return SimplifyOrInst(LHS, RHS, Q, MaxRecurse); + case Instruction::Xor: + return SimplifyXorInst(LHS, RHS, Q, MaxRecurse); + case Instruction::FAdd: + return SimplifyFAddInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); + case Instruction::FSub: + return SimplifyFSubInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); + case Instruction::FMul: + return SimplifyFMulInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); + case Instruction::FDiv: + return SimplifyFDivInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); + case Instruction::FRem: + return SimplifyFRemInst(LHS, RHS, FastMathFlags(), Q, MaxRecurse); + default: + llvm_unreachable("Unexpected opcode"); + } +} + +/// Given operands for a BinaryOperator, see if we can fold the result. +/// If not, this returns null. +/// Try to use FastMathFlags when folding the result. +static Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, + const FastMathFlags &FMF, const SimplifyQuery &Q, + unsigned MaxRecurse) { + switch (Opcode) { + case Instruction::FAdd: + return SimplifyFAddInst(LHS, RHS, FMF, Q, MaxRecurse); + case Instruction::FSub: + return SimplifyFSubInst(LHS, RHS, FMF, Q, MaxRecurse); + case Instruction::FMul: + return SimplifyFMulInst(LHS, RHS, FMF, Q, MaxRecurse); + case Instruction::FDiv: + return SimplifyFDivInst(LHS, RHS, FMF, Q, MaxRecurse); + default: + return SimplifyBinOp(Opcode, LHS, RHS, Q, MaxRecurse); + } +} + +Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, + const SimplifyQuery &Q) { + return ::SimplifyBinOp(Opcode, LHS, RHS, Q, RecursionLimit); +} + +Value *llvm::SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS, + FastMathFlags FMF, const SimplifyQuery &Q) { + return ::SimplifyBinOp(Opcode, LHS, RHS, FMF, Q, RecursionLimit); +} + +/// Given operands for a CmpInst, see if we can fold the result. +static Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const SimplifyQuery &Q, unsigned MaxRecurse) { + if (CmpInst::isIntPredicate((CmpInst::Predicate)Predicate)) + return SimplifyICmpInst(Predicate, LHS, RHS, Q, MaxRecurse); + return SimplifyFCmpInst(Predicate, LHS, RHS, FastMathFlags(), Q, MaxRecurse); +} + +Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS, + const SimplifyQuery &Q) { + return ::SimplifyCmpInst(Predicate, LHS, RHS, Q, RecursionLimit); +} + +static bool IsIdempotent(Intrinsic::ID ID) { + switch (ID) { + default: return false; + + // Unary idempotent: f(f(x)) = f(x) + case Intrinsic::fabs: + case Intrinsic::floor: + case Intrinsic::ceil: + case Intrinsic::trunc: + case Intrinsic::rint: + case Intrinsic::nearbyint: + case Intrinsic::round: + case Intrinsic::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::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::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; + } + default: + break; + } + + return nullptr; +} + +static Value *simplifyBinaryIntrinsic(Function *F, Value *Op0, Value *Op1, + const SimplifyQuery &Q) { + Intrinsic::ID IID = F->getIntrinsicID(); + Type *ReturnType = F->getReturnType(); + switch (IID) { + case Intrinsic::usub_with_overflow: + case Intrinsic::ssub_with_overflow: + // X - X -> { 0, false } + if (Op0 == Op1) + return Constant::getNullValue(ReturnType); + LLVM_FALLTHROUGH; + case Intrinsic::uadd_with_overflow: + case Intrinsic::sadd_with_overflow: + // X - undef -> { undef, false } + // undef - X -> { undef, false } + // X + undef -> { undef, false } + // undef + x -> { undef, false } + if (isa<UndefValue>(Op0) || isa<UndefValue>(Op1)) { + return ConstantStruct::get( + cast<StructType>(ReturnType), + {UndefValue::get(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 (match(Op0, m_Undef()) || match(Op1, m_Undef())) + 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 (match(Op0, m_Undef()) || match(Op1, m_Undef())) + 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 || match(Op0, m_Undef()) || match(Op1, m_Undef())) + 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::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; + + // If one argument is undef, return the other argument. + if (match(Op0, m_Undef())) + return Op1; + if (match(Op1, m_Undef())) + return Op0; + + // If one argument is NaN, return other or NaN appropriately. + bool PropagateNaN = IID == Intrinsic::minimum || IID == Intrinsic::maximum; + if (match(Op0, m_NaN())) + return PropagateNaN ? Op0 : Op1; + if (match(Op1, m_NaN())) + return PropagateNaN ? Op1 : 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; + + // min(X, -Inf) --> -Inf (and commuted variant) + // max(X, +Inf) --> +Inf (and commuted variant) + bool UseNegInf = IID == Intrinsic::minnum || IID == Intrinsic::minimum; + const APFloat *C; + if ((match(Op0, m_APFloat(C)) && C->isInfinity() && + C->isNegative() == UseNegInf) || + (match(Op1, m_APFloat(C)) && C->isInfinity() && + C->isNegative() == UseNegInf)) + return ConstantFP::getInfinity(ReturnType, UseNegInf); + + // TODO: minnum(nnan x, inf) -> x + // TODO: minnum(nnan ninf x, flt_max) -> x + // TODO: maxnum(nnan x, -inf) -> x + // TODO: maxnum(nnan ninf x, -flt_max) -> 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 (match(Op0, m_Undef()) && match(Op1, m_Undef())) + return UndefValue::get(F->getReturnType()); + + // If shift amount is undef, assume it is zero. + if (match(ShAmtArg, m_Undef())) + return Call->getArgOperand(IID == Intrinsic::fshl ? 0 : 1); + + const APInt *ShAmtC; + if (match(ShAmtArg, m_APInt(ShAmtC))) { + // If there's effectively no shift, return the 1st arg or 2nd arg. + APInt BitWidth = APInt(ShAmtC->getBitWidth(), ShAmtC->getBitWidth()); + if (ShAmtC->urem(BitWidth).isNullValue()) + return Call->getArgOperand(IID == Intrinsic::fshl ? 0 : 1); + } + return nullptr; + } + case Intrinsic::fma: + case Intrinsic::fmuladd: { + Value *Op0 = Call->getArgOperand(0); + Value *Op1 = Call->getArgOperand(1); + Value *Op2 = Call->getArgOperand(2); + if (Value *V = simplifyFPOp({ Op0, Op1, Op2 })) + return V; + return nullptr; + } + default: + return nullptr; + } +} + +Value *llvm::SimplifyCall(CallBase *Call, const SimplifyQuery &Q) { + Value *Callee = Call->getCalledValue(); + + // call undef -> undef + // call null -> undef + if (isa<UndefValue>(Callee) || isa<ConstantPointerNull>(Callee)) + return UndefValue::get(Call->getType()); + + Function *F = dyn_cast<Function>(Callee); + if (!F) + return nullptr; + + if (F->isIntrinsic()) + if (Value *Ret = simplifyIntrinsic(Call, Q)) + return Ret; + + if (!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) + return nullptr; + ConstantArgs.push_back(C); + } + + return ConstantFoldCall(Call, F, ConstantArgs, Q.TLI); +} + +/// See if we can compute a simplified version of this instruction. +/// If not, this returns null. + +Value *llvm::SimplifyInstruction(Instruction *I, const SimplifyQuery &SQ, + OptimizationRemarkEmitter *ORE) { + const SimplifyQuery Q = SQ.CxtI ? SQ : SQ.getWithInstruction(I); + Value *Result; + + switch (I->getOpcode()) { + default: + Result = ConstantFoldInstruction(I, Q.DL, Q.TLI); + break; + case Instruction::FNeg: + Result = SimplifyFNegInst(I->getOperand(0), I->getFastMathFlags(), Q); + break; + case Instruction::FAdd: + Result = SimplifyFAddInst(I->getOperand(0), I->getOperand(1), + I->getFastMathFlags(), Q); + break; + case Instruction::Add: + Result = + SimplifyAddInst(I->getOperand(0), I->getOperand(1), + Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), + Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q); + break; + case Instruction::FSub: + Result = SimplifyFSubInst(I->getOperand(0), I->getOperand(1), + I->getFastMathFlags(), Q); + break; + case Instruction::Sub: + Result = + SimplifySubInst(I->getOperand(0), I->getOperand(1), + Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), + Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q); + break; + case Instruction::FMul: + Result = SimplifyFMulInst(I->getOperand(0), I->getOperand(1), + I->getFastMathFlags(), Q); + break; + case Instruction::Mul: + Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), Q); + break; + case Instruction::SDiv: + Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), Q); + break; + case Instruction::UDiv: + Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), Q); + break; + case Instruction::FDiv: + Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), + I->getFastMathFlags(), Q); + break; + case Instruction::SRem: + Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), Q); + break; + case Instruction::URem: + Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), Q); + break; + case Instruction::FRem: + Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), + I->getFastMathFlags(), Q); + break; + case Instruction::Shl: + Result = + SimplifyShlInst(I->getOperand(0), I->getOperand(1), + Q.IIQ.hasNoSignedWrap(cast<BinaryOperator>(I)), + Q.IIQ.hasNoUnsignedWrap(cast<BinaryOperator>(I)), Q); + break; + case Instruction::LShr: + Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1), + Q.IIQ.isExact(cast<BinaryOperator>(I)), Q); + break; + case Instruction::AShr: + Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1), + Q.IIQ.isExact(cast<BinaryOperator>(I)), Q); + break; + case Instruction::And: + Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), Q); + break; + case Instruction::Or: + Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), Q); + break; + case Instruction::Xor: + Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), Q); + break; + case Instruction::ICmp: + Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(), + I->getOperand(0), I->getOperand(1), Q); + break; + case Instruction::FCmp: + Result = + SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(), I->getOperand(0), + I->getOperand(1), I->getFastMathFlags(), Q); + break; + case Instruction::Select: + Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1), + I->getOperand(2), Q); + break; + case Instruction::GetElementPtr: { + SmallVector<Value *, 8> Ops(I->op_begin(), I->op_end()); + Result = SimplifyGEPInst(cast<GetElementPtrInst>(I)->getSourceElementType(), + Ops, Q); + break; + } + case Instruction::InsertValue: { + InsertValueInst *IV = cast<InsertValueInst>(I); + Result = SimplifyInsertValueInst(IV->getAggregateOperand(), + IV->getInsertedValueOperand(), + IV->getIndices(), Q); + break; + } + case Instruction::InsertElement: { + auto *IE = cast<InsertElementInst>(I); + Result = SimplifyInsertElementInst(IE->getOperand(0), IE->getOperand(1), + IE->getOperand(2), Q); + break; + } + case Instruction::ExtractValue: { + auto *EVI = cast<ExtractValueInst>(I); + Result = SimplifyExtractValueInst(EVI->getAggregateOperand(), + EVI->getIndices(), Q); + break; + } + case Instruction::ExtractElement: { + auto *EEI = cast<ExtractElementInst>(I); + Result = SimplifyExtractElementInst(EEI->getVectorOperand(), + EEI->getIndexOperand(), Q); + break; + } + case Instruction::ShuffleVector: { + auto *SVI = cast<ShuffleVectorInst>(I); + Result = SimplifyShuffleVectorInst(SVI->getOperand(0), SVI->getOperand(1), + SVI->getMask(), SVI->getType(), Q); + break; + } + case Instruction::PHI: + Result = SimplifyPHINode(cast<PHINode>(I), Q); + break; + case Instruction::Call: { + Result = SimplifyCall(cast<CallInst>(I), Q); + break; + } +#define HANDLE_CAST_INST(num, opc, clas) case Instruction::opc: +#include "llvm/IR/Instruction.def" +#undef HANDLE_CAST_INST + Result = + SimplifyCastInst(I->getOpcode(), I->getOperand(0), I->getType(), Q); + break; + case Instruction::Alloca: + // No simplifications for Alloca and it can't be constant folded. + Result = nullptr; + break; + } + + // In general, it is possible for computeKnownBits to determine all bits in a + // value even when the operands are not all constants. + if (!Result && I->getType()->isIntOrIntVectorTy()) { + KnownBits Known = computeKnownBits(I, Q.DL, /*Depth*/ 0, Q.AC, I, Q.DT, ORE); + if (Known.isConstant()) + Result = ConstantInt::get(I->getType(), Known.getConstant()); + } + + /// If called on unreachable code, the above logic may report that the + /// instruction simplified to itself. Make life easier for users by + /// detecting that case here, returning a safe value instead. + return Result == I ? UndefValue::get(I->getType()) : Result; +} + +/// Implementation of recursive simplification through an instruction's +/// uses. +/// +/// This is the common implementation of the recursive simplification routines. +/// If we have a pre-simplified value in 'SimpleV', that is forcibly used to +/// replace the instruction 'I'. Otherwise, we simply add 'I' to the list of +/// instructions to process and attempt to simplify it using +/// InstructionSimplify. Recursively visited users which could not be +/// simplified themselves are to the optional UnsimplifiedUsers set for +/// further processing by the caller. +/// +/// This routine returns 'true' only when *it* simplifies something. The passed +/// in simplified value does not count toward this. +static bool replaceAndRecursivelySimplifyImpl( + Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI, + const DominatorTree *DT, AssumptionCache *AC, + SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr) { + bool Simplified = false; + SmallSetVector<Instruction *, 8> Worklist; + const DataLayout &DL = I->getModule()->getDataLayout(); + + // If we have an explicit value to collapse to, do that round of the + // simplification loop by hand initially. + if (SimpleV) { + for (User *U : I->users()) + if (U != I) + Worklist.insert(cast<Instruction>(U)); + + // Replace the instruction with its simplified value. + I->replaceAllUsesWith(SimpleV); + + // Gracefully handle edge cases where the instruction is not wired into any + // parent block. + if (I->getParent() && !I->isEHPad() && !I->isTerminator() && + !I->mayHaveSideEffects()) + I->eraseFromParent(); + } else { + Worklist.insert(I); + } + + // Note that we must test the size on each iteration, the worklist can grow. + for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) { + I = Worklist[Idx]; + + // See if this instruction simplifies. + SimpleV = SimplifyInstruction(I, {DL, TLI, DT, AC}); + if (!SimpleV) { + if (UnsimplifiedUsers) + UnsimplifiedUsers->insert(I); + continue; + } + + Simplified = true; + + // Stash away all the uses of the old instruction so we can check them for + // recursive simplifications after a RAUW. This is cheaper than checking all + // uses of To on the recursive step in most cases. + for (User *U : I->users()) + Worklist.insert(cast<Instruction>(U)); + + // Replace the instruction with its simplified value. + I->replaceAllUsesWith(SimpleV); + + // Gracefully handle edge cases where the instruction is not wired into any + // parent block. + if (I->getParent() && !I->isEHPad() && !I->isTerminator() && + !I->mayHaveSideEffects()) + I->eraseFromParent(); + } + return Simplified; +} + +bool llvm::recursivelySimplifyInstruction(Instruction *I, + const TargetLibraryInfo *TLI, + const DominatorTree *DT, + AssumptionCache *AC) { + return replaceAndRecursivelySimplifyImpl(I, nullptr, TLI, DT, AC, nullptr); +} + +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 &); +} |