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/IR/PassManager.h"
30#include "llvm/IR/ValueHandle.h"
31#include <utility>
32
33namespace llvm {
34
35class AAResults;
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 AAResults *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 *, std::pair<WeakVH, WeakTrackingVH>>
60 UnderlyingObjCPtrCache;
61
62 bool relatedCheck(const Value *A, const Value *B);
63 bool relatedSelect(const SelectInst *A, const Value *B);
64 bool relatedPHI(const PHINode *A, const Value *B);
65
66public:
67 ProvenanceAnalysis() = default;
68 ProvenanceAnalysis(const ProvenanceAnalysis &) = delete;
69 ProvenanceAnalysis &operator=(const ProvenanceAnalysis &) = delete;
70
71 void setAA(AAResults *aa) { AA = aa; }
72
73 AAResults *getAA() const { return AA; }
74
75 bool related(const Value *A, const Value *B);
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