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       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             : 
      29             : namespace llvm {
      30             : namespace 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.
      38             : class ObjCARCAAResult : public AAResultBase<ObjCARCAAResult> {
      39             :   friend AAResultBase<ObjCARCAAResult>;
      40             : 
      41             :   const DataLayout &DL;
      42             : 
      43             : public:
      44          33 :   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.
      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             : /// Legacy wrapper pass to provide the ObjCARCAAResult object.
      78             : class ObjCARCAAWrapperPass : public ImmutablePass {
      79             :   std::unique_ptr<ObjCARCAAResult> Result;
      80             : 
      81             : public:
      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