LLVM 19.0.0git
Reassociate.h
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1//===- Reassociate.h - Reassociate binary expressions -----------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This pass reassociates commutative expressions in an order that is designed
10// to promote better constant propagation, GCSE, LICM, PRE, etc.
11//
12// For example: 4 + (x + 5) -> x + (4 + 5)
13//
14// In the implementation of this algorithm, constants are assigned rank = 0,
15// function arguments are rank = 1, and other values are assigned ranks
16// corresponding to the reverse post order traversal of current function
17// (starting at 2), which effectively gives values in deep loops higher rank
18// than values not in loops.
19//
20//===----------------------------------------------------------------------===//
21
22#ifndef LLVM_TRANSFORMS_SCALAR_REASSOCIATE_H
23#define LLVM_TRANSFORMS_SCALAR_REASSOCIATE_H
24
25#include "llvm/ADT/DenseMap.h"
27#include "llvm/ADT/SetVector.h"
28#include "llvm/IR/PassManager.h"
29#include "llvm/IR/ValueHandle.h"
30#include <deque>
31
32namespace llvm {
33
34class APInt;
35class BasicBlock;
36class BinaryOperator;
37class Function;
38class Instruction;
39class IRBuilderBase;
40class Value;
41
42/// A private "module" namespace for types and utilities used by Reassociate.
43/// These are implementation details and should not be used by clients.
44namespace reassociate {
45
46struct ValueEntry {
47 unsigned Rank;
49
50 ValueEntry(unsigned R, Value *O) : Rank(R), Op(O) {}
51};
52
53inline bool operator<(const ValueEntry &LHS, const ValueEntry &RHS) {
54 return LHS.Rank > RHS.Rank; // Sort so that highest rank goes to start.
55}
56
57/// Utility class representing a base and exponent pair which form one
58/// factor of some product.
59struct Factor {
61 unsigned Power;
62
63 Factor(Value *Base, unsigned Power) : Base(Base), Power(Power) {}
64};
65
66class XorOpnd;
67
68} // end namespace reassociate
69
70/// Reassociate commutative expressions.
71class ReassociatePass : public PassInfoMixin<ReassociatePass> {
72public:
73 using OrderedSet =
74 SetVector<AssertingVH<Instruction>, std::deque<AssertingVH<Instruction>>>;
75
76protected:
80
81 // Arbitrary, but prevents quadratic behavior.
82 static const unsigned GlobalReassociateLimit = 10;
83 static const unsigned NumBinaryOps =
84 Instruction::BinaryOpsEnd - Instruction::BinaryOpsBegin;
85
86 struct PairMapValue {
89 unsigned Score;
90 bool isValid() const { return Value1 && Value2; }
91 };
93
95
96public:
98
99private:
100 void BuildRankMap(Function &F, ReversePostOrderTraversal<Function *> &RPOT);
101 unsigned getRank(Value *V);
102 void canonicalizeOperands(Instruction *I);
103 void ReassociateExpression(BinaryOperator *I);
104 void RewriteExprTree(BinaryOperator *I,
106 bool HasNUW);
107 Value *OptimizeExpression(BinaryOperator *I,
109 Value *OptimizeAdd(Instruction *I,
111 Value *OptimizeXor(Instruction *I,
113 bool CombineXorOpnd(Instruction *I, reassociate::XorOpnd *Opnd1,
114 APInt &ConstOpnd, Value *&Res);
115 bool CombineXorOpnd(Instruction *I, reassociate::XorOpnd *Opnd1,
116 reassociate::XorOpnd *Opnd2, APInt &ConstOpnd,
117 Value *&Res);
118 Value *buildMinimalMultiplyDAG(IRBuilderBase &Builder,
120 Value *OptimizeMul(BinaryOperator *I,
122 Value *RemoveFactorFromExpression(Value *V, Value *Factor);
123 void EraseInst(Instruction *I);
124 void RecursivelyEraseDeadInsts(Instruction *I, OrderedSet &Insts);
125 void OptimizeInst(Instruction *I);
126 Instruction *canonicalizeNegFPConstantsForOp(Instruction *I, Instruction *Op,
127 Value *OtherOp);
128 Instruction *canonicalizeNegFPConstants(Instruction *I);
129 void BuildPairMap(ReversePostOrderTraversal<Function *> &RPOT);
130};
131
132} // end namespace llvm
133
134#endif // LLVM_TRANSFORMS_SCALAR_REASSOCIATE_H
This file defines the DenseMap class.
#define F(x, y, z)
Definition: MD5.cpp:55
#define I(x, y, z)
Definition: MD5.cpp:58
nary reassociate
This header defines various interfaces for pass management in LLVM.
This file builds on the ADT/GraphTraits.h file to build a generic graph post order iterator.
This file implements a set that has insertion order iteration characteristics.
Value * RHS
Value * LHS
Class for arbitrary precision integers.
Definition: APInt.h:76
A container for analyses that lazily runs them and caches their results.
Definition: PassManager.h:348
This class represents an Operation in the Expression.
Common base class shared among various IRBuilders.
Definition: IRBuilder.h:94
A set of analyses that are preserved following a run of a transformation pass.
Definition: Analysis.h:109
Reassociate commutative expressions.
Definition: Reassociate.h:71
DenseMap< BasicBlock *, unsigned > RankMap
Definition: Reassociate.h:77
DenseMap< AssertingVH< Value >, unsigned > ValueRankMap
Definition: Reassociate.h:78
static const unsigned GlobalReassociateLimit
Definition: Reassociate.h:82
OrderedSet RedoInsts
Definition: Reassociate.h:79
PreservedAnalyses run(Function &F, FunctionAnalysisManager &)
static const unsigned NumBinaryOps
Definition: Reassociate.h:83
DenseMap< std::pair< Value *, Value * >, PairMapValue > PairMap[NumBinaryOps]
Definition: Reassociate.h:92
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: SmallVector.h:586
LLVM Value Representation.
Definition: Value.h:74
A nullable Value handle that is nullable.
Definition: ValueHandle.h:144
Utility class representing a non-constant Xor-operand.
@ BasicBlock
Various leaf nodes.
Definition: ISDOpcodes.h:71
bool operator<(const ValueEntry &LHS, const ValueEntry &RHS)
Definition: Reassociate.h:53
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
A CRTP mix-in to automatically provide informational APIs needed for passes.
Definition: PassManager.h:91
Utility class representing a base and exponent pair which form one factor of some product.
Definition: Reassociate.h:59
Factor(Value *Base, unsigned Power)
Definition: Reassociate.h:63
ValueEntry(unsigned R, Value *O)
Definition: Reassociate.h:50