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//===- InstCombineInternal.h - InstCombine pass internals -------*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
/// \file
/// This file provides internal interfaces used to implement the InstCombine.
#include "llvm/ADT/ArrayRef.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/TargetFolder.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Argument.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstVisitor.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Use.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/InstCombine/InstCombineWorklist.h"
#include "llvm/Transforms/Utils/Local.h"
#include <cassert>
#include <cstdint>
#define DEBUG_TYPE "instcombine"
namespace llvm {
class APInt;
class AssumptionCache;
class CallSite;
class DataLayout;
class DominatorTree;
class GEPOperator;
class GlobalVariable;
class LoopInfo;
class OptimizationRemarkEmitter;
class TargetLibraryInfo;
class User;
/// Assign a complexity or rank value to LLVM Values. This is used to reduce
/// the amount of pattern matching needed for compares and commutative
/// instructions. For example, if we have:
/// icmp ugt X, Constant
/// or
/// xor (add X, Constant), cast Z
/// We do not have to consider the commuted variants of these patterns because
/// canonicalization based on complexity guarantees the above ordering.
/// This routine maps IR values to various complexity ranks:
/// 0 -> undef
/// 1 -> Constants
/// 2 -> Other non-instructions
/// 3 -> Arguments
/// 4 -> Cast and (f)neg/not instructions
/// 5 -> Other instructions
static inline unsigned getComplexity(Value *V) {
if (isa<Instruction>(V)) {
if (isa<CastInst>(V) || BinaryOperator::isNeg(V) ||
BinaryOperator::isFNeg(V) || BinaryOperator::isNot(V))
return 4;
return 5;
if (isa<Argument>(V))
return 3;
return isa<Constant>(V) ? (isa<UndefValue>(V) ? 0 : 1) : 2;
/// Predicate canonicalization reduces the number of patterns that need to be
/// matched by other transforms. For example, we may swap the operands of a
/// conditional branch or select to create a compare with a canonical (inverted)
/// predicate which is then more likely to be matched with other values.
static inline bool isCanonicalPredicate(CmpInst::Predicate Pred) {
switch (Pred) {
case CmpInst::ICMP_NE:
case CmpInst::ICMP_ULE:
case CmpInst::ICMP_SLE:
case CmpInst::ICMP_UGE:
case CmpInst::ICMP_SGE:
// TODO: There are 16 FCMP predicates. Should others be (not) canonical?
case CmpInst::FCMP_ONE:
case CmpInst::FCMP_OLE:
case CmpInst::FCMP_OGE:
return false;
return true;
/// Return the source operand of a potentially bitcasted value while optionally
/// checking if it has one use. If there is no bitcast or the one use check is
/// not met, return the input value itself.
static inline Value *peekThroughBitcast(Value *V, bool OneUseOnly = false) {
if (auto *BitCast = dyn_cast<BitCastInst>(V))
if (!OneUseOnly || BitCast->hasOneUse())
return BitCast->getOperand(0);
// V is not a bitcast or V has more than one use and OneUseOnly is true.
return V;
/// \brief Add one to a Constant
static inline Constant *AddOne(Constant *C) {
return ConstantExpr::getAdd(C, ConstantInt::get(C->getType(), 1));
/// \brief Subtract one from a Constant
static inline Constant *SubOne(Constant *C) {
return ConstantExpr::getSub(C, ConstantInt::get(C->getType(), 1));
/// \brief Return true if the specified value is free to invert (apply ~ to).
/// This happens in cases where the ~ can be eliminated. If WillInvertAllUses
/// is true, work under the assumption that the caller intends to remove all
/// uses of V and only keep uses of ~V.
static inline bool IsFreeToInvert(Value *V, bool WillInvertAllUses) {
// ~(~(X)) -> X.
if (BinaryOperator::isNot(V))
return true;
// Constants can be considered to be not'ed values.
if (isa<ConstantInt>(V))
return true;
// A vector of constant integers can be inverted easily.
if (V->getType()->isVectorTy() && isa<Constant>(V)) {
unsigned NumElts = V->getType()->getVectorNumElements();
for (unsigned i = 0; i != NumElts; ++i) {
Constant *Elt = cast<Constant>(V)->getAggregateElement(i);
if (!Elt)
return false;
if (isa<UndefValue>(Elt))
if (!isa<ConstantInt>(Elt))
return false;
return true;
// Compares can be inverted if all of their uses are being modified to use the
// ~V.
if (isa<CmpInst>(V))
return WillInvertAllUses;
// If `V` is of the form `A + Constant` then `-1 - V` can be folded into `(-1
// - Constant) - A` if we are willing to invert all of the uses.
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V))
if (BO->getOpcode() == Instruction::Add ||
BO->getOpcode() == Instruction::Sub)
if (isa<Constant>(BO->getOperand(0)) || isa<Constant>(BO->getOperand(1)))
return WillInvertAllUses;
return false;
/// \brief Specific patterns of overflow check idioms that we match.
enum OverflowCheckFlavor {
/// \brief Returns the OverflowCheckFlavor corresponding to a overflow_with_op
/// intrinsic.
static inline OverflowCheckFlavor
IntrinsicIDToOverflowCheckFlavor(unsigned ID) {
switch (ID) {
case Intrinsic::uadd_with_overflow:
case Intrinsic::sadd_with_overflow:
case Intrinsic::usub_with_overflow:
case Intrinsic::ssub_with_overflow:
case Intrinsic::umul_with_overflow:
case Intrinsic::smul_with_overflow:
/// \brief The core instruction combiner logic.
/// This class provides both the logic to recursively visit instructions and
/// combine them.
: public InstVisitor<InstCombiner, Instruction *> {
// FIXME: These members shouldn't be public.
/// \brief A worklist of the instructions that need to be simplified.
InstCombineWorklist &Worklist;
/// \brief An IRBuilder that automatically inserts new instructions into the
/// worklist.
using BuilderTy = IRBuilder<TargetFolder, IRBuilderCallbackInserter>;
BuilderTy &Builder;
// Mode in which we are running the combiner.
const bool MinimizeSize;
/// Enable combines that trigger rarely but are costly in compiletime.
const bool ExpensiveCombines;
AliasAnalysis *AA;
// Required analyses.
AssumptionCache &AC;
TargetLibraryInfo &TLI;
DominatorTree &DT;
const DataLayout &DL;
const SimplifyQuery SQ;
OptimizationRemarkEmitter &ORE;
// Optional analyses. When non-null, these can both be used to do better
// combining and will be updated to reflect any changes.
LoopInfo *LI;
bool MadeIRChange = false;
InstCombiner(InstCombineWorklist &Worklist, BuilderTy &Builder,
bool MinimizeSize, bool ExpensiveCombines, AliasAnalysis *AA,
AssumptionCache &AC, TargetLibraryInfo &TLI, DominatorTree &DT,
OptimizationRemarkEmitter &ORE, const DataLayout &DL,
LoopInfo *LI)
: Worklist(Worklist), Builder(Builder), MinimizeSize(MinimizeSize),
ExpensiveCombines(ExpensiveCombines), AA(AA), AC(AC), TLI(TLI), DT(DT),
DL(DL), SQ(DL, &TLI, &DT, &AC), ORE(ORE), LI(LI) {}
/// \brief Run the combiner over the entire worklist until it is empty.
/// \returns true if the IR is changed.
bool run();
AssumptionCache &getAssumptionCache() const { return AC; }
const DataLayout &getDataLayout() const { return DL; }
DominatorTree &getDominatorTree() const { return DT; }
LoopInfo *getLoopInfo() const { return LI; }
TargetLibraryInfo &getTargetLibraryInfo() const { return TLI; }
// Visitation implementation - Implement instruction combining for different
// instruction types. The semantics are as follows:
// Return Value:
// null - No change was made
// I - Change was made, I is still valid, I may be dead though
// otherwise - Change was made, replace I with returned instruction
Instruction *visitAdd(BinaryOperator &I);
Instruction *visitFAdd(BinaryOperator &I);
Value *OptimizePointerDifference(Value *LHS, Value *RHS, Type *Ty);
Instruction *visitSub(BinaryOperator &I);
Instruction *visitFSub(BinaryOperator &I);
Instruction *visitMul(BinaryOperator &I);
Value *foldFMulConst(Instruction *FMulOrDiv, Constant *C,
Instruction *InsertBefore);
Instruction *visitFMul(BinaryOperator &I);
Instruction *visitURem(BinaryOperator &I);
Instruction *visitSRem(BinaryOperator &I);
Instruction *visitFRem(BinaryOperator &I);
bool simplifyDivRemOfSelectWithZeroOp(BinaryOperator &I);
Instruction *commonRemTransforms(BinaryOperator &I);
Instruction *commonIRemTransforms(BinaryOperator &I);
Instruction *commonDivTransforms(BinaryOperator &I);
Instruction *commonIDivTransforms(BinaryOperator &I);
Instruction *visitUDiv(BinaryOperator &I);
Instruction *visitSDiv(BinaryOperator &I);
Instruction *visitFDiv(BinaryOperator &I);
Value *simplifyRangeCheck(ICmpInst *Cmp0, ICmpInst *Cmp1, bool Inverted);
Instruction *visitAnd(BinaryOperator &I);
Instruction *visitOr(BinaryOperator &I);
Instruction *visitXor(BinaryOperator &I);
Instruction *visitShl(BinaryOperator &I);
Instruction *visitAShr(BinaryOperator &I);
Instruction *visitLShr(BinaryOperator &I);
Instruction *commonShiftTransforms(BinaryOperator &I);
Instruction *visitFCmpInst(FCmpInst &I);
Instruction *visitICmpInst(ICmpInst &I);
Instruction *FoldShiftByConstant(Value *Op0, Constant *Op1,
BinaryOperator &I);
Instruction *commonCastTransforms(CastInst &CI);
Instruction *commonPointerCastTransforms(CastInst &CI);
Instruction *visitTrunc(TruncInst &CI);
Instruction *visitZExt(ZExtInst &CI);
Instruction *visitSExt(SExtInst &CI);
Instruction *visitFPTrunc(FPTruncInst &CI);
Instruction *visitFPExt(CastInst &CI);
Instruction *visitFPToUI(FPToUIInst &FI);
Instruction *visitFPToSI(FPToSIInst &FI);
Instruction *visitUIToFP(CastInst &CI);
Instruction *visitSIToFP(CastInst &CI);
Instruction *visitPtrToInt(PtrToIntInst &CI);
Instruction *visitIntToPtr(IntToPtrInst &CI);
Instruction *visitBitCast(BitCastInst &CI);
Instruction *visitAddrSpaceCast(AddrSpaceCastInst &CI);
Instruction *FoldItoFPtoI(Instruction &FI);
Instruction *visitSelectInst(SelectInst &SI);
Instruction *visitCallInst(CallInst &CI);
Instruction *visitInvokeInst(InvokeInst &II);
Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
Instruction *visitPHINode(PHINode &PN);
Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
Instruction *visitAllocaInst(AllocaInst &AI);
Instruction *visitAllocSite(Instruction &FI);
Instruction *visitFree(CallInst &FI);
Instruction *visitLoadInst(LoadInst &LI);
Instruction *visitStoreInst(StoreInst &SI);
Instruction *visitBranchInst(BranchInst &BI);
Instruction *visitFenceInst(FenceInst &FI);
Instruction *visitSwitchInst(SwitchInst &SI);
Instruction *visitReturnInst(ReturnInst &RI);
Instruction *visitInsertValueInst(InsertValueInst &IV);
Instruction *visitInsertElementInst(InsertElementInst &IE);
Instruction *visitExtractElementInst(ExtractElementInst &EI);
Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
Instruction *visitExtractValueInst(ExtractValueInst &EV);
Instruction *visitLandingPadInst(LandingPadInst &LI);
Instruction *visitVAStartInst(VAStartInst &I);
Instruction *visitVACopyInst(VACopyInst &I);
/// Specify what to return for unhandled instructions.
Instruction *visitInstruction(Instruction &I) { return nullptr; }
/// True when DB dominates all uses of DI except UI.
/// UI must be in the same block as DI.
/// The routine checks that the DI parent and DB are different.
bool dominatesAllUses(const Instruction *DI, const Instruction *UI,
const BasicBlock *DB) const;
/// Try to replace select with select operand SIOpd in SI-ICmp sequence.
bool replacedSelectWithOperand(SelectInst *SI, const ICmpInst *Icmp,
const unsigned SIOpd);
/// Try to replace instruction \p I with value \p V which are pointers
/// in different address space.
/// \return true if successful.
bool replacePointer(Instruction &I, Value *V);
bool shouldChangeType(unsigned FromBitWidth, unsigned ToBitWidth) const;
bool shouldChangeType(Type *From, Type *To) const;
Value *dyn_castNegVal(Value *V) const;
Value *dyn_castFNegVal(Value *V, bool NoSignedZero = false) const;
Type *FindElementAtOffset(PointerType *PtrTy, int64_t Offset,
SmallVectorImpl<Value *> &NewIndices);
/// Classify whether a cast is worth optimizing.
/// This is a helper to decide whether the simplification of
/// logic(cast(A), cast(B)) to cast(logic(A, B)) should be performed.
/// \param CI The cast we are interested in.
/// \return true if this cast actually results in any code being generated and
/// if it cannot already be eliminated by some other transformation.
bool shouldOptimizeCast(CastInst *CI);
/// \brief Try to optimize a sequence of instructions checking if an operation
/// on LHS and RHS overflows.
/// If this overflow check is done via one of the overflow check intrinsics,
/// then CtxI has to be the call instruction calling that intrinsic. If this
/// overflow check is done by arithmetic followed by a compare, then CtxI has
/// to be the arithmetic instruction.
/// If a simplification is possible, stores the simplified result of the
/// operation in OperationResult and result of the overflow check in
/// OverflowResult, and return true. If no simplification is possible,
/// returns false.
bool OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS, Value *RHS,
Instruction &CtxI, Value *&OperationResult,
Constant *&OverflowResult);
Instruction *visitCallSite(CallSite CS);
Instruction *tryOptimizeCall(CallInst *CI);
bool transformConstExprCastCall(CallSite CS);
Instruction *transformCallThroughTrampoline(CallSite CS,
IntrinsicInst *Tramp);
/// Transform (zext icmp) to bitwise / integer operations in order to
/// eliminate it.
/// \param ICI The icmp of the (zext icmp) pair we are interested in.
/// \parem CI The zext of the (zext icmp) pair we are interested in.
/// \param DoTransform Pass false to just test whether the given (zext icmp)
/// would be transformed. Pass true to actually perform the transformation.
/// \return null if the transformation cannot be performed. If the
/// transformation can be performed the new instruction that replaces the
/// (zext icmp) pair will be returned (if \p DoTransform is false the
/// unmodified \p ICI will be returned in this case).
Instruction *transformZExtICmp(ICmpInst *ICI, ZExtInst &CI,
bool DoTransform = true);
Instruction *transformSExtICmp(ICmpInst *ICI, Instruction &CI);
bool willNotOverflowSignedAdd(const Value *LHS, const Value *RHS,
const Instruction &CxtI) const {
return computeOverflowForSignedAdd(LHS, RHS, &CxtI) ==
bool willNotOverflowUnsignedAdd(const Value *LHS, const Value *RHS,
const Instruction &CxtI) const {
return computeOverflowForUnsignedAdd(LHS, RHS, &CxtI) ==
bool willNotOverflowSignedSub(const Value *LHS, const Value *RHS,
const Instruction &CxtI) const;
bool willNotOverflowUnsignedSub(const Value *LHS, const Value *RHS,
const Instruction &CxtI) const;
bool willNotOverflowSignedMul(const Value *LHS, const Value *RHS,
const Instruction &CxtI) const;
bool willNotOverflowUnsignedMul(const Value *LHS, const Value *RHS,
const Instruction &CxtI) const {
return computeOverflowForUnsignedMul(LHS, RHS, &CxtI) ==
Value *EmitGEPOffset(User *GEP);
Instruction *scalarizePHI(ExtractElementInst &EI, PHINode *PN);
Value *EvaluateInDifferentElementOrder(Value *V, ArrayRef<int> Mask);
Instruction *foldCastedBitwiseLogic(BinaryOperator &I);
Instruction *narrowBinOp(TruncInst &Trunc);
Instruction *narrowRotate(TruncInst &Trunc);
Instruction *optimizeBitCastFromPhi(CastInst &CI, PHINode *PN);
/// Determine if a pair of casts can be replaced by a single cast.
/// \param CI1 The first of a pair of casts.
/// \param CI2 The second of a pair of casts.
/// \return 0 if the cast pair cannot be eliminated, otherwise returns an
/// Instruction::CastOps value for a cast that can replace the pair, casting
/// CI1->getSrcTy() to CI2->getDstTy().
/// \see CastInst::isEliminableCastPair
Instruction::CastOps isEliminableCastPair(const CastInst *CI1,
const CastInst *CI2);
Value *foldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction &CxtI);
Value *foldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS, Instruction &CxtI);
Value *foldXorOfICmps(ICmpInst *LHS, ICmpInst *RHS);
/// Optimize (fcmp)&(fcmp) or (fcmp)|(fcmp).
/// NOTE: Unlike most of instcombine, this returns a Value which should
/// already be inserted into the function.
Value *foldLogicOfFCmps(FCmpInst *LHS, FCmpInst *RHS, bool IsAnd);
Value *foldAndOrOfICmpsOfAndWithPow2(ICmpInst *LHS, ICmpInst *RHS,
bool JoinedByAnd, Instruction &CxtI);
/// \brief Inserts an instruction \p New before instruction \p Old
/// Also adds the new instruction to the worklist and returns \p New so that
/// it is suitable for use as the return from the visitation patterns.
Instruction *InsertNewInstBefore(Instruction *New, Instruction &Old) {
assert(New && !New->getParent() &&
"New instruction already inserted into a basic block!");
BasicBlock *BB = Old.getParent();
BB->getInstList().insert(Old.getIterator(), New); // Insert inst
return New;
/// \brief Same as InsertNewInstBefore, but also sets the debug loc.
Instruction *InsertNewInstWith(Instruction *New, Instruction &Old) {
return InsertNewInstBefore(New, Old);
/// \brief A combiner-aware RAUW-like routine.
/// This method is to be used when an instruction is found to be dead,
/// replaceable with another preexisting expression. Here we add all uses of
/// I to the worklist, replace all uses of I with the new value, then return
/// I, so that the inst combiner will know that I was modified.
Instruction *replaceInstUsesWith(Instruction &I, Value *V) {
// If there are no uses to replace, then we return nullptr to indicate that
// no changes were made to the program.
if (I.use_empty()) return nullptr;
Worklist.AddUsersToWorkList(I); // Add all modified instrs to worklist.
// If we are replacing the instruction with itself, this must be in a
// segment of unreachable code, so just clobber the instruction.
if (&I == V)
V = UndefValue::get(I.getType());
DEBUG(dbgs() << "IC: Replacing " << I << "\n"
<< " with " << *V << '\n');
return &I;
/// Creates a result tuple for an overflow intrinsic \p II with a given
/// \p Result and a constant \p Overflow value.
Instruction *CreateOverflowTuple(IntrinsicInst *II, Value *Result,
Constant *Overflow) {
Constant *V[] = {UndefValue::get(Result->getType()), Overflow};
StructType *ST = cast<StructType>(II->getType());
Constant *Struct = ConstantStruct::get(ST, V);
return InsertValueInst::Create(Struct, Result, 0);
/// \brief Combiner aware instruction erasure.
/// When dealing with an instruction that has side effects or produces a void
/// value, we can't rely on DCE to delete the instruction. Instead, visit
/// methods should return the value returned by this function.
Instruction *eraseInstFromFunction(Instruction &I) {
DEBUG(dbgs() << "IC: ERASE " << I << '\n');
assert(I.use_empty() && "Cannot erase instruction that is used!");
// Make sure that we reprocess all operands now that we reduced their
// use counts.
if (I.getNumOperands() < 8) {
for (Use &Operand : I.operands())
if (auto *Inst = dyn_cast<Instruction>(Operand))
MadeIRChange = true;
return nullptr; // Don't do anything with FI
void computeKnownBits(const Value *V, KnownBits &Known,
unsigned Depth, const Instruction *CxtI) const {
llvm::computeKnownBits(V, Known, DL, Depth, &AC, CxtI, &DT);
KnownBits computeKnownBits(const Value *V, unsigned Depth,
const Instruction *CxtI) const {
return llvm::computeKnownBits(V, DL, Depth, &AC, CxtI, &DT);
bool isKnownToBeAPowerOfTwo(const Value *V, bool OrZero = false,
unsigned Depth = 0,
const Instruction *CxtI = nullptr) {
return llvm::isKnownToBeAPowerOfTwo(V, DL, OrZero, Depth, &AC, CxtI, &DT);
bool MaskedValueIsZero(const Value *V, const APInt &Mask, unsigned Depth = 0,
const Instruction *CxtI = nullptr) const {
return llvm::MaskedValueIsZero(V, Mask, DL, Depth, &AC, CxtI, &DT);
unsigned ComputeNumSignBits(const Value *Op, unsigned Depth = 0,
const Instruction *CxtI = nullptr) const {
return llvm::ComputeNumSignBits(Op, DL, Depth, &AC, CxtI, &DT);
OverflowResult computeOverflowForUnsignedMul(const Value *LHS,
const Value *RHS,
const Instruction *CxtI) const {
return llvm::computeOverflowForUnsignedMul(LHS, RHS, DL, &AC, CxtI, &DT);
OverflowResult computeOverflowForUnsignedAdd(const Value *LHS,
const Value *RHS,
const Instruction *CxtI) const {
return llvm::computeOverflowForUnsignedAdd(LHS, RHS, DL, &AC, CxtI, &DT);
OverflowResult computeOverflowForSignedAdd(const Value *LHS,
const Value *RHS,
const Instruction *CxtI) const {
return llvm::computeOverflowForSignedAdd(LHS, RHS, DL, &AC, CxtI, &DT);
/// Maximum size of array considered when transforming.
uint64_t MaxArraySizeForCombine;
/// \brief Performs a few simplifications for operators which are associative
/// or commutative.
bool SimplifyAssociativeOrCommutative(BinaryOperator &I);
/// \brief Tries to simplify binary operations which some other binary
/// operation distributes over.
/// It does this by either by factorizing out common terms (eg "(A*B)+(A*C)"
/// -> "A*(B+C)") or expanding out if this results in simplifications (eg: "A
/// & (B | C) -> (A&B) | (A&C)" if this is a win). Returns the simplified
/// value, or null if it didn't simplify.
Value *SimplifyUsingDistributiveLaws(BinaryOperator &I);
// Binary Op helper for select operations where the expression can be
// efficiently reorganized.
Value *SimplifySelectsFeedingBinaryOp(BinaryOperator &I, Value *LHS,
Value *RHS);
/// This tries to simplify binary operations by factorizing out common terms
/// (e. g. "(A*B)+(A*C)" -> "A*(B+C)").
Value *tryFactorization(BinaryOperator &, Instruction::BinaryOps, Value *,
Value *, Value *, Value *);
/// Match a select chain which produces one of three values based on whether
/// the LHS is less than, equal to, or greater than RHS respectively.
/// Return true if we matched a three way compare idiom. The LHS, RHS, Less,
/// Equal and Greater values are saved in the matching process and returned to
/// the caller.
bool matchThreeWayIntCompare(SelectInst *SI, Value *&LHS, Value *&RHS,
ConstantInt *&Less, ConstantInt *&Equal,
ConstantInt *&Greater);
/// \brief Attempts to replace V with a simpler value based on the demanded
/// bits.
Value *SimplifyDemandedUseBits(Value *V, APInt DemandedMask, KnownBits &Known,
unsigned Depth, Instruction *CxtI);
bool SimplifyDemandedBits(Instruction *I, unsigned Op,
const APInt &DemandedMask, KnownBits &Known,
unsigned Depth = 0);
/// Helper routine of SimplifyDemandedUseBits. It computes KnownZero/KnownOne
/// bits. It also tries to handle simplifications that can be done based on
/// DemandedMask, but without modifying the Instruction.
Value *SimplifyMultipleUseDemandedBits(Instruction *I,
const APInt &DemandedMask,
KnownBits &Known,
unsigned Depth, Instruction *CxtI);
/// Helper routine of SimplifyDemandedUseBits. It tries to simplify demanded
/// bit for "r1 = shr x, c1; r2 = shl r1, c2" instruction sequence.
Value *simplifyShrShlDemandedBits(
Instruction *Shr, const APInt &ShrOp1, Instruction *Shl,
const APInt &ShlOp1, const APInt &DemandedMask, KnownBits &Known);
/// \brief Tries to simplify operands to an integer instruction based on its
/// demanded bits.
bool SimplifyDemandedInstructionBits(Instruction &Inst);
Value *SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
APInt &UndefElts, unsigned Depth = 0);
Value *SimplifyVectorOp(BinaryOperator &Inst);
/// Given a binary operator, cast instruction, or select which has a PHI node
/// as operand #0, see if we can fold the instruction into the PHI (which is
/// only possible if all operands to the PHI are constants).
Instruction *foldOpIntoPhi(Instruction &I, PHINode *PN);
/// Given an instruction with a select as one operand and a constant as the
/// other operand, try to fold the binary operator into the select arguments.
/// This also works for Cast instructions, which obviously do not have a
/// second operand.
Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI);
/// This is a convenience wrapper function for the above two functions.
Instruction *foldOpWithConstantIntoOperand(BinaryOperator &I);
Instruction *foldAddWithConstant(BinaryOperator &Add);
/// \brief Try to rotate an operation below a PHI node, using PHI nodes for
/// its operands.
Instruction *FoldPHIArgOpIntoPHI(PHINode &PN);
Instruction *FoldPHIArgBinOpIntoPHI(PHINode &PN);
Instruction *FoldPHIArgGEPIntoPHI(PHINode &PN);
Instruction *FoldPHIArgLoadIntoPHI(PHINode &PN);
Instruction *FoldPHIArgZextsIntoPHI(PHINode &PN);
/// If an integer typed PHI has only one use which is an IntToPtr operation,
/// replace the PHI with an existing pointer typed PHI if it exists. Otherwise
/// insert a new pointer typed PHI and replace the original one.
Instruction *FoldIntegerTypedPHI(PHINode &PN);
/// Helper function for FoldPHIArgXIntoPHI() to set debug location for the
/// folded operation.
void PHIArgMergedDebugLoc(Instruction *Inst, PHINode &PN);
Instruction *foldGEPICmp(GEPOperator *GEPLHS, Value *RHS,
ICmpInst::Predicate Cond, Instruction &I);
Instruction *foldAllocaCmp(ICmpInst &ICI, const AllocaInst *Alloca,
const Value *Other);
Instruction *foldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP,
GlobalVariable *GV, CmpInst &ICI,
ConstantInt *AndCst = nullptr);
Instruction *foldFCmpIntToFPConst(FCmpInst &I, Instruction *LHSI,
Constant *RHSC);
Instruction *foldICmpAddOpConst(Value *X, ConstantInt *CI,
ICmpInst::Predicate Pred);
Instruction *foldICmpWithCastAndCast(ICmpInst &ICI);
Instruction *foldICmpUsingKnownBits(ICmpInst &Cmp);
Instruction *foldICmpWithConstant(ICmpInst &Cmp);
Instruction *foldICmpInstWithConstant(ICmpInst &Cmp);
Instruction *foldICmpInstWithConstantNotInt(ICmpInst &Cmp);
Instruction *foldICmpBinOp(ICmpInst &Cmp);
Instruction *foldICmpEquality(ICmpInst &Cmp);
Instruction *foldICmpWithZero(ICmpInst &Cmp);
Instruction *foldICmpSelectConstant(ICmpInst &Cmp, SelectInst *Select,
ConstantInt *C);
Instruction *foldICmpTruncConstant(ICmpInst &Cmp, TruncInst *Trunc,
const APInt &C);
Instruction *foldICmpAndConstant(ICmpInst &Cmp, BinaryOperator *And,
const APInt &C);
Instruction *foldICmpXorConstant(ICmpInst &Cmp, BinaryOperator *Xor,
const APInt &C);
Instruction *foldICmpOrConstant(ICmpInst &Cmp, BinaryOperator *Or,
const APInt &C);
Instruction *foldICmpMulConstant(ICmpInst &Cmp, BinaryOperator *Mul,
const APInt &C);
Instruction *foldICmpShlConstant(ICmpInst &Cmp, BinaryOperator *Shl,
const APInt &C);
Instruction *foldICmpShrConstant(ICmpInst &Cmp, BinaryOperator *Shr,
const APInt &C);
Instruction *foldICmpUDivConstant(ICmpInst &Cmp, BinaryOperator *UDiv,
const APInt &C);
Instruction *foldICmpDivConstant(ICmpInst &Cmp, BinaryOperator *Div,
const APInt &C);
Instruction *foldICmpSubConstant(ICmpInst &Cmp, BinaryOperator *Sub,
const APInt &C);
Instruction *foldICmpAddConstant(ICmpInst &Cmp, BinaryOperator *Add,
const APInt &C);
Instruction *foldICmpAndConstConst(ICmpInst &Cmp, BinaryOperator *And,
const APInt &C1);
Instruction *foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And,
const APInt &C1, const APInt &C2);
Instruction *foldICmpShrConstConst(ICmpInst &I, Value *ShAmt, const APInt &C1,
const APInt &C2);
Instruction *foldICmpShlConstConst(ICmpInst &I, Value *ShAmt, const APInt &C1,
const APInt &C2);
Instruction *foldICmpBinOpEqualityWithConstant(ICmpInst &Cmp,
BinaryOperator *BO,
const APInt &C);
Instruction *foldICmpIntrinsicWithConstant(ICmpInst &ICI, const APInt &C);
// Helpers of visitSelectInst().
Instruction *foldSelectExtConst(SelectInst &Sel);
Instruction *foldSelectOpOp(SelectInst &SI, Instruction *TI, Instruction *FI);
Instruction *foldSelectIntoOp(SelectInst &SI, Value *, Value *);
Instruction *foldSPFofSPF(Instruction *Inner, SelectPatternFlavor SPF1,
Value *A, Value *B, Instruction &Outer,
SelectPatternFlavor SPF2, Value *C);
Instruction *foldSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
Instruction *OptAndOp(BinaryOperator *Op, ConstantInt *OpRHS,
ConstantInt *AndRHS, BinaryOperator &TheAnd);
Value *insertRangeTest(Value *V, const APInt &Lo, const APInt &Hi,
bool isSigned, bool Inside);
Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
Instruction *MatchBSwap(BinaryOperator &I);
bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
Instruction *SimplifyElementUnorderedAtomicMemCpy(AtomicMemCpyInst *AMI);
Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
Instruction *SimplifyMemSet(MemSetInst *MI);
Value *EvaluateInDifferentType(Value *V, Type *Ty, bool isSigned);
/// \brief Returns a value X such that Val = X * Scale, or null if none.
/// If the multiplication is known not to overflow then NoSignedWrap is set.
Value *Descale(Value *Val, APInt Scale, bool &NoSignedWrap);
} // end namespace llvm