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 31namespace llvm { 32 class Value; 33 class DataLayout; 34 class PHINode; 35 class SelectInst; 36} 37 38namespace llvm { 39namespace 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. 50class 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 64public: 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