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 /// \brief 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: ObjCARCAAResult(const DataLayout & DL)44 explicit ObjCARCAAResult(const DataLayout &DL) : AAResultBase(), DL(DL) {} ObjCARCAAResult(ObjCARCAAResult && Arg)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. invalidate(Function &,const PreservedAnalyses &)51 bool invalidate(Function &, const PreservedAnalyses &) { return false; } 52 53 AliasResult alias(const MemoryLocation &LocA, const MemoryLocation &LocB); 54 bool pointsToConstantMemory(const MemoryLocation &Loc, bool OrLocal); 55 56 using AAResultBase::getModRefBehavior; 57 FunctionModRefBehavior getModRefBehavior(const Function *F); 58 59 using AAResultBase::getModRefInfo; 60 ModRefInfo getModRefInfo(ImmutableCallSite CS, const MemoryLocation &Loc); 61 }; 62 63 /// Analysis pass providing a never-invalidated alias analysis result. 64 class ObjCARCAA : public AnalysisInfoMixin<ObjCARCAA> { 65 friend AnalysisInfoMixin<ObjCARCAA>; 66 static char PassID; 67 68 public: 69 typedef ObjCARCAAResult Result; 70 71 ObjCARCAAResult run(Function &F, AnalysisManager<Function> &AM); 72 }; 73 74 /// Legacy wrapper pass to provide the ObjCARCAAResult object. 75 class ObjCARCAAWrapperPass : public ImmutablePass { 76 std::unique_ptr<ObjCARCAAResult> Result; 77 78 public: 79 static char ID; 80 81 ObjCARCAAWrapperPass(); 82 getResult()83 ObjCARCAAResult &getResult() { return *Result; } getResult()84 const ObjCARCAAResult &getResult() const { return *Result; } 85 86 bool doInitialization(Module &M) override; 87 bool doFinalization(Module &M) override; 88 void getAnalysisUsage(AnalysisUsage &AU) const override; 89 }; 90 91 } // namespace objcarc 92 } // namespace llvm 93 94 #endif 95