include/llvm/Analysis/ObjCARCAliasAnalysis.h

   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<ObjCARCAAResult> {
  38   friend AAResultBase<ObjCARCAAResult>;
  39
  40   const DataLayout &DL;
  41
  42 public:
  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.
  69 class ObjCARCAA : public AnalysisInfoMixin<ObjCARCAA> {
  70   friend AnalysisInfoMixin<ObjCARCAA>;
  71   static AnalysisKey Key;
  72
  73 public:
  74   typedef ObjCARCAAResult Result;
  75
  76   ObjCARCAAResult run(Function &F, FunctionAnalysisManager &AM);
  77 };
  78
  79 /// Legacy wrapper pass to provide the ObjCARCAAResult object.
  80 class ObjCARCAAWrapperPass : public ImmutablePass {
  81   std::unique_ptr<ObjCARCAAResult> Result;
  82
  83 public:
  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