1//===- ObjCARCAliasAnalysis.h - ObjC ARC Alias Analysis ---------*- 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/// \file
9/// This file declares a simple ARC-aware AliasAnalysis using special knowledge
10/// of Objective C to enhance other optimization passes which rely on the Alias
11/// Analysis infrastructure.
12///
13/// WARNING: This file knows about certain library functions. It recognizes them
14/// by name, and hardwires knowledge of their semantics.
15///
16/// WARNING: This file knows about how certain Objective-C library functions are
17/// used. Naive LLVM IR transformations which would otherwise be
18/// behavior-preserving may break these assumptions.
19///
20//===----------------------------------------------------------------------===//
21
22#ifndef LLVM_ANALYSIS_OBJCARCALIASANALYSIS_H
23#define LLVM_ANALYSIS_OBJCARCALIASANALYSIS_H
24
25#include "llvm/Analysis/AliasAnalysis.h"
26#include "llvm/Pass.h"
27
28namespace llvm {
29namespace objcarc {
30
31/// This is a simple alias analysis implementation that uses knowledge
32/// of ARC constructs to answer queries.
33///
34/// TODO: This class could be generalized to know about other ObjC-specific
35/// tricks. Such as knowing that ivars in the non-fragile ABI are non-aliasing
36/// even though their offsets are dynamic.
37class ObjCARCAAResult : public AAResultBase<ObjCARCAAResult> {
38  friend AAResultBase<ObjCARCAAResult>;
39
40  const DataLayout &DL;
41
42public:
43  explicit ObjCARCAAResult(const DataLayout &DL) : AAResultBase(), DL(DL) {}
44  ObjCARCAAResult(ObjCARCAAResult &&Arg)
45      : AAResultBase(std::move(Arg)), DL(Arg.DL) {}
46
47  /// Handle invalidation events from the new pass manager.
48  ///
49  /// By definition, this result is stateless and so remains valid.
50  bool invalidate(Function &, const PreservedAnalyses &,
51                  FunctionAnalysisManager::Invalidator &) {
52    return false;
53  }
54
55  AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
56                    AAQueryInfo &AAQI);
57  bool pointsToConstantMemory(const MemoryLocation &Loc, AAQueryInfo &AAQI,
58                              bool OrLocal);
59
60  using AAResultBase::getModRefBehavior;
61  FunctionModRefBehavior getModRefBehavior(const Function *F);
62
63  using AAResultBase::getModRefInfo;
64  ModRefInfo getModRefInfo(const CallBase *Call, const MemoryLocation &Loc,
65                           AAQueryInfo &AAQI);
66};
67
68/// Analysis pass providing a never-invalidated alias analysis result.
69class ObjCARCAA : public AnalysisInfoMixin<ObjCARCAA> {
70  friend AnalysisInfoMixin<ObjCARCAA>;
71  static AnalysisKey Key;
72
73public:
74  typedef ObjCARCAAResult Result;
75
76  ObjCARCAAResult run(Function &F, FunctionAnalysisManager &AM);
77};
78
79/// Legacy wrapper pass to provide the ObjCARCAAResult object.
80class ObjCARCAAWrapperPass : public ImmutablePass {
81  std::unique_ptr<ObjCARCAAResult> Result;
82
83public:
84  static char ID;
85
86  ObjCARCAAWrapperPass();
87
88  ObjCARCAAResult &getResult() { return *Result; }
89  const ObjCARCAAResult &getResult() const { return *Result; }
90
91  bool doInitialization(Module &M) override;
92  bool doFinalization(Module &M) override;
93  void getAnalysisUsage(AnalysisUsage &AU) const override;
94};
95
96} // namespace objcarc
97} // namespace llvm
98
99#endif
100