1303231Sdim//===- Reassociate.h - Reassociate binary expressions -----------*- C++ -*-===// 2303231Sdim// 3353358Sdim// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4353358Sdim// See https://llvm.org/LICENSE.txt for license information. 5353358Sdim// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6303231Sdim// 7303231Sdim//===----------------------------------------------------------------------===// 8303231Sdim// 9303231Sdim// This pass reassociates commutative expressions in an order that is designed 10303231Sdim// to promote better constant propagation, GCSE, LICM, PRE, etc. 11303231Sdim// 12303231Sdim// For example: 4 + (x + 5) -> x + (4 + 5) 13303231Sdim// 14303231Sdim// In the implementation of this algorithm, constants are assigned rank = 0, 15303231Sdim// function arguments are rank = 1, and other values are assigned ranks 16303231Sdim// corresponding to the reverse post order traversal of current function 17303231Sdim// (starting at 2), which effectively gives values in deep loops higher rank 18303231Sdim// than values not in loops. 19303231Sdim// 20303231Sdim//===----------------------------------------------------------------------===// 21303231Sdim 22303231Sdim#ifndef LLVM_TRANSFORMS_SCALAR_REASSOCIATE_H 23303231Sdim#define LLVM_TRANSFORMS_SCALAR_REASSOCIATE_H 24303231Sdim 25327952Sdim#include "llvm/ADT/DenseMap.h" 26303231Sdim#include "llvm/ADT/PostOrderIterator.h" 27303231Sdim#include "llvm/ADT/SetVector.h" 28303231Sdim#include "llvm/IR/IRBuilder.h" 29303231Sdim#include "llvm/IR/PassManager.h" 30327952Sdim#include "llvm/IR/ValueHandle.h" 31341825Sdim#include <deque> 32303231Sdim 33303231Sdimnamespace llvm { 34303231Sdim 35327952Sdimclass APInt; 36327952Sdimclass BasicBlock; 37327952Sdimclass BinaryOperator; 38327952Sdimclass Function; 39327952Sdimclass Instruction; 40327952Sdimclass Value; 41327952Sdim 42303231Sdim/// A private "module" namespace for types and utilities used by Reassociate. 43303231Sdim/// These are implementation details and should not be used by clients. 44303231Sdimnamespace reassociate { 45327952Sdim 46303231Sdimstruct ValueEntry { 47303231Sdim unsigned Rank; 48303231Sdim Value *Op; 49327952Sdim 50303231Sdim ValueEntry(unsigned R, Value *O) : Rank(R), Op(O) {} 51303231Sdim}; 52327952Sdim 53303231Sdiminline bool operator<(const ValueEntry &LHS, const ValueEntry &RHS) { 54303231Sdim return LHS.Rank > RHS.Rank; // Sort so that highest rank goes to start. 55303231Sdim} 56303231Sdim 57341825Sdim/// Utility class representing a base and exponent pair which form one 58303231Sdim/// factor of some product. 59303231Sdimstruct Factor { 60303231Sdim Value *Base; 61303231Sdim unsigned Power; 62327952Sdim 63303231Sdim Factor(Value *Base, unsigned Power) : Base(Base), Power(Power) {} 64303231Sdim}; 65303231Sdim 66303231Sdimclass XorOpnd; 67303231Sdim 68327952Sdim} // end namespace reassociate 69327952Sdim 70303231Sdim/// Reassociate commutative expressions. 71303231Sdimclass ReassociatePass : public PassInfoMixin<ReassociatePass> { 72341825Sdimpublic: 73341825Sdim using OrderedSet = 74341825Sdim SetVector<AssertingVH<Instruction>, std::deque<AssertingVH<Instruction>>>; 75341825Sdim 76341825Sdimprotected: 77303231Sdim DenseMap<BasicBlock *, unsigned> RankMap; 78303231Sdim DenseMap<AssertingVH<Value>, unsigned> ValueRankMap; 79341825Sdim OrderedSet RedoInsts; 80327952Sdim 81327952Sdim // Arbitrary, but prevents quadratic behavior. 82327952Sdim static const unsigned GlobalReassociateLimit = 10; 83327952Sdim static const unsigned NumBinaryOps = 84327952Sdim Instruction::BinaryOpsEnd - Instruction::BinaryOpsBegin; 85327952Sdim 86353358Sdim struct PairMapValue { 87353358Sdim WeakVH Value1; 88353358Sdim WeakVH Value2; 89353358Sdim unsigned Score; 90353358Sdim bool isValid() const { return Value1 && Value2; } 91353358Sdim }; 92353358Sdim DenseMap<std::pair<Value *, Value *>, PairMapValue> PairMap[NumBinaryOps]; 93353358Sdim 94303231Sdim bool MadeChange; 95303231Sdim 96303231Sdimpublic: 97303231Sdim PreservedAnalyses run(Function &F, FunctionAnalysisManager &); 98303231Sdim 99303231Sdimprivate: 100314564Sdim void BuildRankMap(Function &F, ReversePostOrderTraversal<Function *> &RPOT); 101303231Sdim unsigned getRank(Value *V); 102303231Sdim void canonicalizeOperands(Instruction *I); 103303231Sdim void ReassociateExpression(BinaryOperator *I); 104303231Sdim void RewriteExprTree(BinaryOperator *I, 105303231Sdim SmallVectorImpl<reassociate::ValueEntry> &Ops); 106303231Sdim Value *OptimizeExpression(BinaryOperator *I, 107303231Sdim SmallVectorImpl<reassociate::ValueEntry> &Ops); 108303231Sdim Value *OptimizeAdd(Instruction *I, 109303231Sdim SmallVectorImpl<reassociate::ValueEntry> &Ops); 110303231Sdim Value *OptimizeXor(Instruction *I, 111303231Sdim SmallVectorImpl<reassociate::ValueEntry> &Ops); 112303231Sdim bool CombineXorOpnd(Instruction *I, reassociate::XorOpnd *Opnd1, 113303231Sdim APInt &ConstOpnd, Value *&Res); 114303231Sdim bool CombineXorOpnd(Instruction *I, reassociate::XorOpnd *Opnd1, 115303231Sdim reassociate::XorOpnd *Opnd2, APInt &ConstOpnd, 116303231Sdim Value *&Res); 117303231Sdim Value *buildMinimalMultiplyDAG(IRBuilder<> &Builder, 118303231Sdim SmallVectorImpl<reassociate::Factor> &Factors); 119303231Sdim Value *OptimizeMul(BinaryOperator *I, 120303231Sdim SmallVectorImpl<reassociate::ValueEntry> &Ops); 121303231Sdim Value *RemoveFactorFromExpression(Value *V, Value *Factor); 122303231Sdim void EraseInst(Instruction *I); 123341825Sdim void RecursivelyEraseDeadInsts(Instruction *I, OrderedSet &Insts); 124303231Sdim void OptimizeInst(Instruction *I); 125360784Sdim Instruction *canonicalizeNegFPConstantsForOp(Instruction *I, Instruction *Op, 126360784Sdim Value *OtherOp); 127360784Sdim Instruction *canonicalizeNegFPConstants(Instruction *I); 128327952Sdim void BuildPairMap(ReversePostOrderTraversal<Function *> &RPOT); 129303231Sdim}; 130303231Sdim 131327952Sdim} // end namespace llvm 132327952Sdim 133303231Sdim#endif // LLVM_TRANSFORMS_SCALAR_REASSOCIATE_H 134