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 
28 namespace llvm {
29 namespace 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.
37 class ObjCARCAAResult : public AAResultBase {
38   const DataLayout &DL;
39 
40 public:
ObjCARCAAResult(const DataLayout & DL)41   explicit ObjCARCAAResult(const DataLayout &DL) : DL(DL) {}
ObjCARCAAResult(ObjCARCAAResult && Arg)42   ObjCARCAAResult(ObjCARCAAResult &&Arg)
43       : AAResultBase(std::move(Arg)), DL(Arg.DL) {}
44 
45   /// Handle invalidation events from the new pass manager.
46   ///
47   /// By definition, this result is stateless and so remains valid.
invalidate(Function &,const PreservedAnalyses &,FunctionAnalysisManager::Invalidator &)48   bool invalidate(Function &, const PreservedAnalyses &,
49                   FunctionAnalysisManager::Invalidator &) {
50     return false;
51   }
52 
53   AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB,
54                     AAQueryInfo &AAQI, const Instruction *CtxI);
55   ModRefInfo getModRefInfoMask(const MemoryLocation &Loc, AAQueryInfo &AAQI,
56                                bool IgnoreLocals);
57 
58   using AAResultBase::getMemoryEffects;
59   MemoryEffects getMemoryEffects(const Function *F);
60 
61   using AAResultBase::getModRefInfo;
62   ModRefInfo getModRefInfo(const CallBase *Call, const MemoryLocation &Loc,
63                            AAQueryInfo &AAQI);
64 };
65 
66 /// Analysis pass providing a never-invalidated alias analysis result.
67 class ObjCARCAA : public AnalysisInfoMixin<ObjCARCAA> {
68   friend AnalysisInfoMixin<ObjCARCAA>;
69   static AnalysisKey Key;
70 
71 public:
72   typedef ObjCARCAAResult Result;
73 
74   ObjCARCAAResult run(Function &F, FunctionAnalysisManager &AM);
75 };
76 
77 } // namespace objcarc
78 } // namespace llvm
79 
80 #endif
81