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 // 10 /// \file 11 /// 12 /// This file declares a special form of Alias Analysis called ``Provenance 13 /// Analysis''. The word ``provenance'' refers to the history of the ownership 14 /// of an object. Thus ``Provenance Analysis'' is an analysis which attempts to 15 /// use various techniques to determine if locally 16 /// 17 /// WARNING: This file knows about certain library functions. It recognizes them 18 /// by name, and hardwires knowledge of their semantics. 19 /// 20 /// WARNING: This file knows about how certain Objective-C library functions are 21 /// used. Naive LLVM IR transformations which would otherwise be 22 /// behavior-preserving may break these assumptions. 23 // 24 //===----------------------------------------------------------------------===// 25 26 #ifndef LLVM_LIB_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H 27 #define LLVM_LIB_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H 28 29 #include "llvm/ADT/DenseMap.h" 30 #include "llvm/Analysis/AliasAnalysis.h" 31 #include "llvm/IR/ValueHandle.h" 32 #include <utility> 33 34 namespace llvm { 35 36 class DataLayout; 37 class PHINode; 38 class SelectInst; 39 class Value; 40 41 namespace objcarc { 42 43 /// This is similar to BasicAliasAnalysis, and it uses many of the same 44 /// techniques, except it uses special ObjC-specific reasoning about pointer 45 /// relationships. 46 /// 47 /// In this context ``Provenance'' is defined as the history of an object's 48 /// ownership. Thus ``Provenance Analysis'' is defined by using the notion of 49 /// an ``independent provenance source'' of a pointer to determine whether or 50 /// not two pointers have the same provenance source and thus could 51 /// potentially be related. 52 class ProvenanceAnalysis { 53 AliasAnalysis *AA; 54 55 using ValuePairTy = std::pair<const Value *, const Value *>; 56 using CachedResultsTy = DenseMap<ValuePairTy, bool>; 57 58 CachedResultsTy CachedResults; 59 60 DenseMap<const Value *, WeakTrackingVH> UnderlyingObjCPtrCache; 61 62 bool relatedCheck(const Value *A, const Value *B, const DataLayout &DL); 63 bool relatedSelect(const SelectInst *A, const Value *B); 64 bool relatedPHI(const PHINode *A, const Value *B); 65 66 public: 67 ProvenanceAnalysis() = default; 68 ProvenanceAnalysis(const ProvenanceAnalysis &) = delete; 69 ProvenanceAnalysis &operator=(const ProvenanceAnalysis &) = delete; 70 71 void setAA(AliasAnalysis *aa) { AA = aa; } 72 73 AliasAnalysis *getAA() const { return AA; } 74 75 bool related(const Value *A, const Value *B, const DataLayout &DL); 76 77 void clear() { 78 CachedResults.clear(); 79 UnderlyingObjCPtrCache.clear(); 80 } 81 }; 82 83 } // end namespace objcarc 84 85 } // end namespace llvm 86 87 #endif // LLVM_LIB_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H 88
