clang  7.0.0svn
Visibility.h
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1 //===--- Visibility.h - Visibility enumeration and utilities ----*- 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 ///
10 /// \file
11 /// \brief Defines the clang::Visibility enumeration and various utility
12 /// functions.
13 ///
14 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_BASIC_VISIBILITY_H
16 #define LLVM_CLANG_BASIC_VISIBILITY_H
17 
18 #include "clang/Basic/Linkage.h"
19 #include <cassert>
20 
21 namespace clang {
22 
23 /// \brief Describes the different kinds of visibility that a declaration
24 /// may have.
25 ///
26 /// Visibility determines how a declaration interacts with the dynamic
27 /// linker. It may also affect whether the symbol can be found by runtime
28 /// symbol lookup APIs.
29 ///
30 /// Visibility is not described in any language standard and
31 /// (nonetheless) sometimes has odd behavior. Not all platforms
32 /// support all visibility kinds.
33 enum Visibility {
34  /// Objects with "hidden" visibility are not seen by the dynamic
35  /// linker.
37 
38  /// Objects with "protected" visibility are seen by the dynamic
39  /// linker but always dynamically resolve to an object within this
40  /// shared object.
42 
43  /// Objects with "default" visibility are seen by the dynamic linker
44  /// and act like normal objects.
46 };
47 
49  return L < R ? L : R;
50 }
51 
52 class LinkageInfo {
53  uint8_t linkage_ : 3;
54  uint8_t visibility_ : 2;
55  uint8_t explicit_ : 1;
56 
57  void setVisibility(Visibility V, bool E) { visibility_ = V; explicit_ = E; }
58 public:
59  LinkageInfo() : linkage_(ExternalLinkage), visibility_(DefaultVisibility),
60  explicit_(false) {}
62  : linkage_(L), visibility_(V), explicit_(E) {
63  assert(getLinkage() == L && getVisibility() == V &&
64  isVisibilityExplicit() == E && "Enum truncated!");
65  }
66 
67  static LinkageInfo external() {
68  return LinkageInfo();
69  }
70  static LinkageInfo internal() {
72  }
75  }
76  static LinkageInfo none() {
77  return LinkageInfo(NoLinkage, DefaultVisibility, false);
78  }
81  }
82 
83  Linkage getLinkage() const { return (Linkage)linkage_; }
84  Visibility getVisibility() const { return (Visibility)visibility_; }
85  bool isVisibilityExplicit() const { return explicit_; }
86 
87  void setLinkage(Linkage L) { linkage_ = L; }
88 
91  }
92  void mergeLinkage(LinkageInfo other) {
93  mergeLinkage(other.getLinkage());
94  }
95 
97  Linkage ThisL = getLinkage();
98  if (!isExternallyVisible(L)) {
99  if (ThisL == VisibleNoLinkage)
100  ThisL = NoLinkage;
101  else if (ThisL == ExternalLinkage)
102  ThisL = UniqueExternalLinkage;
103  }
104  setLinkage(ThisL);
105  }
108  }
109 
110  /// Merge in the visibility 'newVis'.
111  void mergeVisibility(Visibility newVis, bool newExplicit) {
112  Visibility oldVis = getVisibility();
113 
114  // Never increase visibility.
115  if (oldVis < newVis)
116  return;
117 
118  // If the new visibility is the same as the old and the new
119  // visibility isn't explicit, we have nothing to add.
120  if (oldVis == newVis && !newExplicit)
121  return;
122 
123  // Otherwise, we're either decreasing visibility or making our
124  // existing visibility explicit.
125  setVisibility(newVis, newExplicit);
126  }
129  }
130 
131  /// Merge both linkage and visibility.
132  void merge(LinkageInfo other) {
133  mergeLinkage(other);
134  mergeVisibility(other);
135  }
136 
137  /// Merge linkage and conditionally merge visibility.
138  void mergeMaybeWithVisibility(LinkageInfo other, bool withVis) {
139  mergeLinkage(other);
140  if (withVis) mergeVisibility(other);
141  }
142 };
143 }
144 
145 #endif // LLVM_CLANG_BASIC_VISIBILITY_H
void setLinkage(Linkage L)
Definition: Visibility.h:87
External linkage, which indicates that the entity can be referred to from other translation units...
Definition: Linkage.h:60
No linkage, which means that the entity is unique and can only be referred to from within its scope...
Definition: Linkage.h:27
Objects with "hidden" visibility are not seen by the dynamic linker.
Definition: Visibility.h:36
void mergeVisibility(Visibility newVis, bool newExplicit)
Merge in the visibility &#39;newVis&#39;.
Definition: Visibility.h:111
Visibility getVisibility() const
Definition: Visibility.h:84
Visibility minVisibility(Visibility L, Visibility R)
Definition: Visibility.h:48
Linkage
Describes the different kinds of linkage (C++ [basic.link], C99 6.2.2) that an entity may have...
Definition: Linkage.h:24
Objects with "default" visibility are seen by the dynamic linker and act like normal objects...
Definition: Visibility.h:45
Visibility
Describes the different kinds of visibility that a declaration may have.
Definition: Visibility.h:33
LinkageInfo(Linkage L, Visibility V, bool E)
Definition: Visibility.h:61
Defines the Linkage enumeration and various utility functions.
void mergeExternalVisibility(Linkage L)
Definition: Visibility.h:96
Linkage getLinkage() const
Definition: Visibility.h:83
Objects with "protected" visibility are seen by the dynamic linker but always dynamically resolve to ...
Definition: Visibility.h:41
bool isExternallyVisible(Linkage L)
Definition: Linkage.h:86
static LinkageInfo visible_none()
Definition: Visibility.h:79
static LinkageInfo external()
Definition: Visibility.h:67
#define false
Definition: stdbool.h:33
Linkage minLinkage(Linkage L1, Linkage L2)
Compute the minimum linkage given two linkages.
Definition: Linkage.h:115
Dataflow Directional Tag Classes.
External linkage within a unique namespace.
Definition: Linkage.h:41
void mergeExternalVisibility(LinkageInfo Other)
Definition: Visibility.h:106
void mergeVisibility(LinkageInfo other)
Definition: Visibility.h:127
bool isVisibilityExplicit() const
Definition: Visibility.h:85
void mergeLinkage(Linkage L)
Definition: Visibility.h:89
void mergeLinkage(LinkageInfo other)
Definition: Visibility.h:92
Internal linkage, which indicates that the entity can be referred to from within the translation unit...
Definition: Linkage.h:32
void merge(LinkageInfo other)
Merge both linkage and visibility.
Definition: Visibility.h:132
No linkage according to the standard, but is visible from other translation units because of types de...
Definition: Linkage.h:45
void mergeMaybeWithVisibility(LinkageInfo other, bool withVis)
Merge linkage and conditionally merge visibility.
Definition: Visibility.h:138
static LinkageInfo none()
Definition: Visibility.h:76
static LinkageInfo uniqueExternal()
Definition: Visibility.h:73