1//===- ProvenanceAnalysis.h - ObjC ARC Optimization -------------*- C++ -*-===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 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#include "llvm/IR/ValueHandle.h" 31#include <utility> 32 33namespace llvm { 34 35class DataLayout; 36class PHINode; 37class SelectInst; 38class Value; 39 40namespace objcarc { 41 42/// This is similar to BasicAliasAnalysis, and it uses many of the same 43/// techniques, except it uses special ObjC-specific reasoning about pointer 44/// relationships. 45/// 46/// In this context ``Provenance'' is defined as the history of an object's 47/// ownership. Thus ``Provenance Analysis'' is defined by using the notion of 48/// an ``independent provenance source'' of a pointer to determine whether or 49/// not two pointers have the same provenance source and thus could 50/// potentially be related. 51class ProvenanceAnalysis { 52 AliasAnalysis *AA; 53 54 using ValuePairTy = std::pair<const Value *, const Value *>; 55 using CachedResultsTy = DenseMap<ValuePairTy, bool>; 56 57 CachedResultsTy CachedResults; 58 59 DenseMap<const Value *, WeakTrackingVH> UnderlyingObjCPtrCache; 60 61 bool relatedCheck(const Value *A, const Value *B, const DataLayout &DL); 62 bool relatedSelect(const SelectInst *A, const Value *B); 63 bool relatedPHI(const PHINode *A, const Value *B); 64 65public: 66 ProvenanceAnalysis() = default; 67 ProvenanceAnalysis(const ProvenanceAnalysis &) = delete; 68 ProvenanceAnalysis &operator=(const ProvenanceAnalysis &) = delete; 69 70 void setAA(AliasAnalysis *aa) { AA = aa; } 71 72 AliasAnalysis *getAA() const { return AA; } 73 74 bool related(const Value *A, const Value *B, const DataLayout &DL); 75 76 void clear() { 77 CachedResults.clear(); 78 UnderlyingObjCPtrCache.clear(); 79 } 80}; 81 82} // end namespace objcarc 83 84} // end namespace llvm 85 86#endif // LLVM_LIB_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H 87