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