329 lines
14 KiB
C
329 lines
14 KiB
C
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//===-- InstructionSimplify.h - Fold instrs into simpler forms --*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares routines for folding instructions into simpler forms
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// that do not require creating new instructions. This does constant folding
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// ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
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// returning a constant ("and i32 %x, 0" -> "0") or an already existing value
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// ("and i32 %x, %x" -> "%x"). If the simplification is also an instruction
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// then it dominates the original instruction.
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//
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// These routines implicitly resolve undef uses. The easiest way to be safe when
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// using these routines to obtain simplified values for existing instructions is
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// to always replace all uses of the instructions with the resulting simplified
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// values. This will prevent other code from seeing the same undef uses and
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// resolving them to different values.
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//
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// These routines are designed to tolerate moderately incomplete IR, such as
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// instructions that are not connected to basic blocks yet. However, they do
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// require that all the IR that they encounter be valid. In particular, they
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// require that all non-constant values be defined in the same function, and the
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// same call context of that function (and not split between caller and callee
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// contexts of a directly recursive call, for example).
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//
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// Additionally, these routines can't simplify to the instructions that are not
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// def-reachable, meaning we can't just scan the basic block for instructions
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// to simplify to.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
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#define LLVM_ANALYSIS_INSTRUCTIONSIMPLIFY_H
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#include "llvm/IR/Instruction.h"
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#include "llvm/IR/Operator.h"
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namespace llvm {
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template <typename T, typename... TArgs> class AnalysisManager;
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template <class T> class ArrayRef;
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class AssumptionCache;
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class BinaryOperator;
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class CallBase;
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class DataLayout;
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class DominatorTree;
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class Function;
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struct LoopStandardAnalysisResults;
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class MDNode;
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class OptimizationRemarkEmitter;
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class Pass;
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template <class T, unsigned n> class SmallSetVector;
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class TargetLibraryInfo;
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class Type;
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class Value;
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/// InstrInfoQuery provides an interface to query additional information for
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/// instructions like metadata or keywords like nsw, which provides conservative
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/// results if the users specified it is safe to use.
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struct InstrInfoQuery {
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InstrInfoQuery(bool UMD) : UseInstrInfo(UMD) {}
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InstrInfoQuery() : UseInstrInfo(true) {}
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bool UseInstrInfo = true;
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MDNode *getMetadata(const Instruction *I, unsigned KindID) const {
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if (UseInstrInfo)
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return I->getMetadata(KindID);
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return nullptr;
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}
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template <class InstT> bool hasNoUnsignedWrap(const InstT *Op) const {
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if (UseInstrInfo)
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return Op->hasNoUnsignedWrap();
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return false;
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}
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template <class InstT> bool hasNoSignedWrap(const InstT *Op) const {
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if (UseInstrInfo)
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return Op->hasNoSignedWrap();
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return false;
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}
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bool isExact(const BinaryOperator *Op) const {
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if (UseInstrInfo && isa<PossiblyExactOperator>(Op))
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return cast<PossiblyExactOperator>(Op)->isExact();
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return false;
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}
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};
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struct SimplifyQuery {
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const DataLayout &DL;
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const TargetLibraryInfo *TLI = nullptr;
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const DominatorTree *DT = nullptr;
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AssumptionCache *AC = nullptr;
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const Instruction *CxtI = nullptr;
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// Wrapper to query additional information for instructions like metadata or
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// keywords like nsw, which provides conservative results if those cannot
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// be safely used.
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const InstrInfoQuery IIQ;
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/// Controls whether simplifications are allowed to constrain the range of
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/// possible values for uses of undef. If it is false, simplifications are not
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/// allowed to assume a particular value for a use of undef for example.
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bool CanUseUndef = true;
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SimplifyQuery(const DataLayout &DL, const Instruction *CXTI = nullptr)
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: DL(DL), CxtI(CXTI) {}
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SimplifyQuery(const DataLayout &DL, const TargetLibraryInfo *TLI,
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const DominatorTree *DT = nullptr,
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AssumptionCache *AC = nullptr,
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const Instruction *CXTI = nullptr, bool UseInstrInfo = true,
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bool CanUseUndef = true)
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: DL(DL), TLI(TLI), DT(DT), AC(AC), CxtI(CXTI), IIQ(UseInstrInfo),
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CanUseUndef(CanUseUndef) {}
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SimplifyQuery getWithInstruction(Instruction *I) const {
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SimplifyQuery Copy(*this);
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Copy.CxtI = I;
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return Copy;
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}
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SimplifyQuery getWithoutUndef() const {
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SimplifyQuery Copy(*this);
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Copy.CanUseUndef = false;
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return Copy;
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}
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/// If CanUseUndef is true, returns whether \p V is undef.
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/// Otherwise always return false.
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bool isUndefValue(Value *V) const {
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if (!CanUseUndef)
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return false;
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return isa<UndefValue>(V);
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}
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};
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// NOTE: the explicit multiple argument versions of these functions are
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// deprecated.
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// Please use the SimplifyQuery versions in new code.
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/// Given operand for an FNeg, fold the result or return null.
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Value *SimplifyFNegInst(Value *Op, FastMathFlags FMF,
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const SimplifyQuery &Q);
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/// Given operands for an Add, fold the result or return null.
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Value *SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
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const SimplifyQuery &Q);
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/// Given operands for a Sub, fold the result or return null.
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Value *SimplifySubInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
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const SimplifyQuery &Q);
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/// Given operands for an FAdd, fold the result or return null.
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Value *SimplifyFAddInst(Value *LHS, Value *RHS, FastMathFlags FMF,
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const SimplifyQuery &Q);
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/// Given operands for an FSub, fold the result or return null.
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Value *SimplifyFSubInst(Value *LHS, Value *RHS, FastMathFlags FMF,
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const SimplifyQuery &Q);
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/// Given operands for an FMul, fold the result or return null.
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Value *SimplifyFMulInst(Value *LHS, Value *RHS, FastMathFlags FMF,
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const SimplifyQuery &Q);
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/// Given operands for the multiplication of a FMA, fold the result or return
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/// null. In contrast to SimplifyFMulInst, this function will not perform
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/// simplifications whose unrounded results differ when rounded to the argument
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/// type.
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Value *SimplifyFMAFMul(Value *LHS, Value *RHS, FastMathFlags FMF,
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const SimplifyQuery &Q);
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/// Given operands for a Mul, fold the result or return null.
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Value *SimplifyMulInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
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/// Given operands for an SDiv, fold the result or return null.
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Value *SimplifySDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
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/// Given operands for a UDiv, fold the result or return null.
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Value *SimplifyUDivInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
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/// Given operands for an FDiv, fold the result or return null.
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Value *SimplifyFDivInst(Value *LHS, Value *RHS, FastMathFlags FMF,
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const SimplifyQuery &Q);
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/// Given operands for an SRem, fold the result or return null.
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Value *SimplifySRemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
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/// Given operands for a URem, fold the result or return null.
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Value *SimplifyURemInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
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/// Given operands for an FRem, fold the result or return null.
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Value *SimplifyFRemInst(Value *LHS, Value *RHS, FastMathFlags FMF,
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const SimplifyQuery &Q);
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/// Given operands for a Shl, fold the result or return null.
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Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
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const SimplifyQuery &Q);
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/// Given operands for a LShr, fold the result or return null.
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Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
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const SimplifyQuery &Q);
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/// Given operands for a AShr, fold the result or return nulll.
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Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
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const SimplifyQuery &Q);
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/// Given operands for an And, fold the result or return null.
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Value *SimplifyAndInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
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/// Given operands for an Or, fold the result or return null.
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Value *SimplifyOrInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
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/// Given operands for an Xor, fold the result or return null.
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Value *SimplifyXorInst(Value *LHS, Value *RHS, const SimplifyQuery &Q);
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/// Given operands for an ICmpInst, fold the result or return null.
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Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
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const SimplifyQuery &Q);
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/// Given operands for an FCmpInst, fold the result or return null.
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Value *SimplifyFCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
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FastMathFlags FMF, const SimplifyQuery &Q);
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/// Given operands for a SelectInst, fold the result or return null.
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Value *SimplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
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const SimplifyQuery &Q);
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/// Given operands for a GetElementPtrInst, fold the result or return null.
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Value *SimplifyGEPInst(Type *SrcTy, ArrayRef<Value *> Ops,
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const SimplifyQuery &Q);
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/// Given operands for an InsertValueInst, fold the result or return null.
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Value *SimplifyInsertValueInst(Value *Agg, Value *Val, ArrayRef<unsigned> Idxs,
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const SimplifyQuery &Q);
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/// Given operands for an InsertElement, fold the result or return null.
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Value *SimplifyInsertElementInst(Value *Vec, Value *Elt, Value *Idx,
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const SimplifyQuery &Q);
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/// Given operands for an ExtractValueInst, fold the result or return null.
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Value *SimplifyExtractValueInst(Value *Agg, ArrayRef<unsigned> Idxs,
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const SimplifyQuery &Q);
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/// Given operands for an ExtractElementInst, fold the result or return null.
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Value *SimplifyExtractElementInst(Value *Vec, Value *Idx,
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const SimplifyQuery &Q);
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/// Given operands for a CastInst, fold the result or return null.
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Value *SimplifyCastInst(unsigned CastOpc, Value *Op, Type *Ty,
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const SimplifyQuery &Q);
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/// Given operands for a ShuffleVectorInst, fold the result or return null.
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/// See class ShuffleVectorInst for a description of the mask representation.
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Value *SimplifyShuffleVectorInst(Value *Op0, Value *Op1, ArrayRef<int> Mask,
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Type *RetTy, const SimplifyQuery &Q);
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//=== Helper functions for higher up the class hierarchy.
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/// Given operands for a CmpInst, fold the result or return null.
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Value *SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
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const SimplifyQuery &Q);
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/// Given operand for a UnaryOperator, fold the result or return null.
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Value *SimplifyUnOp(unsigned Opcode, Value *Op, const SimplifyQuery &Q);
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/// Given operand for a UnaryOperator, fold the result or return null.
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/// Try to use FastMathFlags when folding the result.
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Value *SimplifyUnOp(unsigned Opcode, Value *Op, FastMathFlags FMF,
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const SimplifyQuery &Q);
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/// Given operands for a BinaryOperator, fold the result or return null.
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Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
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const SimplifyQuery &Q);
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/// Given operands for a BinaryOperator, fold the result or return null.
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/// Try to use FastMathFlags when folding the result.
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Value *SimplifyBinOp(unsigned Opcode, Value *LHS, Value *RHS,
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FastMathFlags FMF, const SimplifyQuery &Q);
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/// Given a callsite, fold the result or return null.
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Value *SimplifyCall(CallBase *Call, const SimplifyQuery &Q);
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/// Given an operand for a Freeze, see if we can fold the result.
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/// If not, this returns null.
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Value *SimplifyFreezeInst(Value *Op, const SimplifyQuery &Q);
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/// See if we can compute a simplified version of this instruction. If not,
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/// return null.
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Value *SimplifyInstruction(Instruction *I, const SimplifyQuery &Q,
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OptimizationRemarkEmitter *ORE = nullptr);
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/// See if V simplifies when its operand Op is replaced with RepOp. If not,
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/// return null.
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/// AllowRefinement specifies whether the simplification can be a refinement,
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/// or whether it needs to be strictly identical.
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Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
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const SimplifyQuery &Q, bool AllowRefinement);
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/// Replace all uses of 'I' with 'SimpleV' and simplify the uses recursively.
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///
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/// This first performs a normal RAUW of I with SimpleV. It then recursively
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/// attempts to simplify those users updated by the operation. The 'I'
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/// instruction must not be equal to the simplified value 'SimpleV'.
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/// If UnsimplifiedUsers is provided, instructions that could not be simplified
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/// are added to it.
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///
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/// The function returns true if any simplifications were performed.
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bool replaceAndRecursivelySimplify(
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Instruction *I, Value *SimpleV, const TargetLibraryInfo *TLI = nullptr,
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const DominatorTree *DT = nullptr, AssumptionCache *AC = nullptr,
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SmallSetVector<Instruction *, 8> *UnsimplifiedUsers = nullptr);
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// These helper functions return a SimplifyQuery structure that contains as
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// many of the optional analysis we use as are currently valid. This is the
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// strongly preferred way of constructing SimplifyQuery in passes.
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const SimplifyQuery getBestSimplifyQuery(Pass &, Function &);
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template <class T, class... TArgs>
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const SimplifyQuery getBestSimplifyQuery(AnalysisManager<T, TArgs...> &,
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Function &);
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const SimplifyQuery getBestSimplifyQuery(LoopStandardAnalysisResults &,
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const DataLayout &);
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} // end namespace llvm
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#endif
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