1 //===- MemCpyOptimizer.h - memcpy optimization ------------------*- 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 performs various transformations related to eliminating memcpy
10 // calls, or transforming sets of stores into memset's.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_TRANSFORMS_SCALAR_MEMCPYOPTIMIZER_H
15 #define LLVM_TRANSFORMS_SCALAR_MEMCPYOPTIMIZER_H
16 
17 #include "llvm/IR/BasicBlock.h"
18 #include "llvm/IR/PassManager.h"
19 
20 namespace llvm {
21 
22 class AAResults;
23 class AllocaInst;
24 class BatchAAResults;
25 class AssumptionCache;
26 class CallBase;
27 class CallInst;
28 class DominatorTree;
29 class Function;
30 class Instruction;
31 class LoadInst;
32 class MemCpyInst;
33 class MemMoveInst;
34 class MemorySSA;
35 class MemorySSAUpdater;
36 class MemSetInst;
37 class PostDominatorTree;
38 class StoreInst;
39 class TargetLibraryInfo;
40 class Value;
41 
42 class MemCpyOptPass : public PassInfoMixin<MemCpyOptPass> {
43   TargetLibraryInfo *TLI = nullptr;
44   AAResults *AA = nullptr;
45   AssumptionCache *AC = nullptr;
46   DominatorTree *DT = nullptr;
47   PostDominatorTree *PDT = nullptr;
48   MemorySSA *MSSA = nullptr;
49   MemorySSAUpdater *MSSAU = nullptr;
50 
51 public:
52   MemCpyOptPass() = default;
53 
54   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
55 
56   // Glue for the old PM.
57   bool runImpl(Function &F, TargetLibraryInfo *TLI, AAResults *AA,
58                AssumptionCache *AC, DominatorTree *DT, PostDominatorTree *PDT,
59                MemorySSA *MSSA);
60 
61 private:
62   // Helper functions
63   bool processStore(StoreInst *SI, BasicBlock::iterator &BBI);
64   bool processStoreOfLoad(StoreInst *SI, LoadInst *LI, const DataLayout &DL,
65                           BasicBlock::iterator &BBI);
66   bool processMemSet(MemSetInst *SI, BasicBlock::iterator &BBI);
67   bool processMemCpy(MemCpyInst *M, BasicBlock::iterator &BBI);
68   bool processMemMove(MemMoveInst *M);
69   bool performCallSlotOptzn(Instruction *cpyLoad, Instruction *cpyStore,
70                             Value *cpyDst, Value *cpySrc, TypeSize cpyLen,
71                             Align cpyAlign, BatchAAResults &BAA,
72                             std::function<CallInst *()> GetC);
73   bool processMemCpyMemCpyDependence(MemCpyInst *M, MemCpyInst *MDep,
74                                      BatchAAResults &BAA);
75   bool processMemSetMemCpyDependence(MemCpyInst *MemCpy, MemSetInst *MemSet,
76                                      BatchAAResults &BAA);
77   bool performMemCpyToMemSetOptzn(MemCpyInst *MemCpy, MemSetInst *MemSet,
78                                   BatchAAResults &BAA);
79   bool processByValArgument(CallBase &CB, unsigned ArgNo);
80   bool processImmutArgument(CallBase &CB, unsigned ArgNo);
81   Instruction *tryMergingIntoMemset(Instruction *I, Value *StartPtr,
82                                     Value *ByteVal);
83   bool moveUp(StoreInst *SI, Instruction *P, const LoadInst *LI);
84   bool performStackMoveOptzn(Instruction *Load, Instruction *Store,
85                              AllocaInst *DestAlloca, AllocaInst *SrcAlloca,
86                              TypeSize Size, BatchAAResults &BAA);
87 
88   void eraseInstruction(Instruction *I);
89   bool iterateOnFunction(Function &F);
90 };
91 
92 } // end namespace llvm
93 
94 #endif // LLVM_TRANSFORMS_SCALAR_MEMCPYOPTIMIZER_H
95