ObjCARCAliasAnalysis.h revision 341825 
1//===- ObjCARCAliasAnalysis.h - ObjC ARC Alias Analysis ---------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9/// \file
10/// This file declares a simple ARC-aware AliasAnalysis using special knowledge
11/// of Objective C to enhance other optimization passes which rely on the Alias
12/// Analysis infrastructure.
13///
14/// WARNING: This file knows about certain library functions. It recognizes them
15/// by name, and hardwires knowledge of their semantics.
16///
17/// WARNING: This file knows about how certain Objective-C library functions are
18/// used. Naive LLVM IR transformations which would otherwise be
19/// behavior-preserving may break these assumptions.
20///
21//===----------------------------------------------------------------------===//
22
23#ifndef LLVM_ANALYSIS_OBJCARCALIASANALYSIS_H
24#define LLVM_ANALYSIS_OBJCARCALIASANALYSIS_H
25
26#include "llvm/Analysis/AliasAnalysis.h"
27#include "llvm/Pass.h"
28
29namespace llvm {
30namespace objcarc {
31
32/// This is a simple alias analysis implementation that uses knowledge
33/// of ARC constructs to answer queries.
34///
35/// TODO: This class could be generalized to know about other ObjC-specific
36/// tricks. Such as knowing that ivars in the non-fragile ABI are non-aliasing
37/// even though their offsets are dynamic.
38class ObjCARCAAResult : public AAResultBase<ObjCARCAAResult> {
39  friend AAResultBase<ObjCARCAAResult>;
40
41  const DataLayout &DL;
42
43public:
44  explicit ObjCARCAAResult(const DataLayout &DL) : AAResultBase(), DL(DL) {}
45  ObjCARCAAResult(ObjCARCAAResult &&Arg)
46      : AAResultBase(std::move(Arg)), DL(Arg.DL) {}
47
48  /// Handle invalidation events from the new pass manager.
49  ///
50  /// By definition, this result is stateless and so remains valid.
51  bool invalidate(Function &, const PreservedAnalyses &,
52                  FunctionAnalysisManager::Invalidator &) {
53    return false;
54  }
55
56  AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB);
57  bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal);
58
59  using AAResultBase::getModRefBehavior;
60  FunctionModRefBehavior getModRefBehavior(const Function *F);
61
62  using AAResultBase::getModRefInfo;
63  ModRefInfo getModRefInfo(ImmutableCallSite CS, const MemoryLocation &Loc);
64};
65
66/// Analysis pass providing a never-invalidated alias analysis result.
67class ObjCARCAA : public AnalysisInfoMixin<ObjCARCAA> {
68  friend AnalysisInfoMixin<ObjCARCAA>;
69  static AnalysisKey Key;
70
71public:
72  typedef ObjCARCAAResult Result;
73
74  ObjCARCAAResult run(Function &F, FunctionAnalysisManager &AM);
75};
76
77/// Legacy wrapper pass to provide the ObjCARCAAResult object.
78class ObjCARCAAWrapperPass : public ImmutablePass {
79  std::unique_ptr<ObjCARCAAResult> Result;
80
81public:
82  static char ID;
83
84  ObjCARCAAWrapperPass();
85
86  ObjCARCAAResult &getResult() { return *Result; }
87  const ObjCARCAAResult &getResult() const { return *Result; }
88
89  bool doInitialization(Module &M) override;
90  bool doFinalization(Module &M) override;
91  void getAnalysisUsage(AnalysisUsage &AU) const override;
92};
93
94} // namespace objcarc
95} // namespace llvm
96
97#endif
98