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_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H
26#define LLVM_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H
27
28#include "llvm/ADT/DenseMap.h"
29
30namespace llvm {
31  class Value;
32  class AliasAnalysis;
33  class PHINode;
34  class SelectInst;
35}
36
37namespace llvm {
38namespace objcarc {
39
40/// \brief This is similar to BasicAliasAnalysis, and it uses many of the same
41/// techniques, except it uses special ObjC-specific reasoning about pointer
42/// relationships.
43///
44/// In this context ``Provenance'' is defined as the history of an object's
45/// ownership. Thus ``Provenance Analysis'' is defined by using the notion of
46/// an ``independent provenance source'' of a pointer to determine whether or
47/// not two pointers have the same provenance source and thus could
48/// potentially be related.
49class ProvenanceAnalysis {
50  AliasAnalysis *AA;
51
52  typedef std::pair<const Value *, const Value *> ValuePairTy;
53  typedef DenseMap<ValuePairTy, bool> CachedResultsTy;
54  CachedResultsTy CachedResults;
55
56  bool relatedCheck(const Value *A, const Value *B);
57  bool relatedSelect(const SelectInst *A, const Value *B);
58  bool relatedPHI(const PHINode *A, const Value *B);
59
60  void operator=(const ProvenanceAnalysis &) LLVM_DELETED_FUNCTION;
61  ProvenanceAnalysis(const ProvenanceAnalysis &) LLVM_DELETED_FUNCTION;
62
63public:
64  ProvenanceAnalysis() {}
65
66  void setAA(AliasAnalysis *aa) { AA = aa; }
67
68  AliasAnalysis *getAA() const { return AA; }
69
70  bool related(const Value *A, const Value *B);
71
72  void clear() {
73    CachedResults.clear();
74  }
75};
76
77} // end namespace objcarc
78} // end namespace llvm
79
80#endif // LLVM_TRANSFORMS_OBJCARC_PROVENANCEANALYSIS_H
81