LLVM  10.0.0svn
ProvenanceAnalysis.h
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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"
30 #include "llvm/IR/ValueHandle.h"
31 #include <utility>
32 
33 namespace llvm {
34 
35 class DataLayout;
36 class PHINode;
37 class SelectInst;
38 class Value;
39 
40 namespace 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.
52  AliasAnalysis *AA;
53 
54  using ValuePairTy = std::pair<const Value *, const Value *>;
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 
65 public:
66  ProvenanceAnalysis() = default;
67  ProvenanceAnalysis(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
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:111
This class represents lattice values for constants.
Definition: AllocatorList.h:23
This class represents the LLVM &#39;select&#39; instruction.
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
bool related(const Value *A, const Value *B, const DataLayout &DL)
LLVM Value Representation.
Definition: Value.h:74
ProvenanceAnalysis & operator=(const ProvenanceAnalysis &)=delete
This is similar to BasicAliasAnalysis, and it uses many of the same techniques, except it uses specia...