1 //===- ProvenanceAnalysis.h - ObjC ARC Optimization ---*- 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 /// 11 /// This file declares a special form of Alias Analysis called ``Provenance 12 /// Analysis''. The word ``provenance'' refers to the history of the ownership 13 /// of an object. Thus ``Provenance Analysis'' is an analysis which attempts to 14 /// use various techniques to determine if locally 15 /// 16 /// WARNING: This file knows about certain library functions. It recognizes them 17 /// by name, and hardwires knowledge of their semantics. 18 /// 19 /// WARNING: This file knows about how certain Objective-C library functions are 20 /// used. Naive LLVM IR transformations which would otherwise be 21 /// behavior-preserving may break these assumptions. 22 /// 23 //===----------------------------------------------------------------------===// 24 25 #ifndef LLVM_LIB_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H 26 #define LLVM_LIB_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H 27 28 #include "llvm/ADT/DenseMap.h" 29 #include "llvm/Analysis/AliasAnalysis.h" 30 31 namespace llvm { 32 class Value; 33 class DataLayout; 34 class PHINode; 35 class SelectInst; 36 } 37 38 namespace llvm { 39 namespace objcarc { 40 41 /// \brief This is similar to BasicAliasAnalysis, and it uses many of the same 42 /// techniques, except it uses special ObjC-specific reasoning about pointer 43 /// relationships. 44 /// 45 /// In this context ``Provenance'' is defined as the history of an object's 46 /// ownership. Thus ``Provenance Analysis'' is defined by using the notion of 47 /// an ``independent provenance source'' of a pointer to determine whether or 48 /// not two pointers have the same provenance source and thus could 49 /// potentially be related. 50 class ProvenanceAnalysis { 51 AliasAnalysis *AA; 52 53 typedef std::pair<const Value *, const Value *> ValuePairTy; 54 typedef DenseMap<ValuePairTy, bool> CachedResultsTy; 55 CachedResultsTy CachedResults; 56 57 bool relatedCheck(const Value *A, const Value *B, const DataLayout &DL); 58 bool relatedSelect(const SelectInst *A, const Value *B); 59 bool relatedPHI(const PHINode *A, const Value *B); 60 61 void operator=(const ProvenanceAnalysis &) = delete; 62 ProvenanceAnalysis(const ProvenanceAnalysis &) = delete; 63 64 public: 65 ProvenanceAnalysis() {} 66 67 void setAA(AliasAnalysis *aa) { AA = aa; } 68 69 AliasAnalysis *getAA() const { return AA; } 70 71 bool related(const Value *A, const Value *B, const DataLayout &DL); 72 73 void clear() { 74 CachedResults.clear(); 75 } 76 }; 77 78 } // end namespace objcarc 79 } // end namespace llvm 80 81 #endif 82
