1 //===--- Visibility.h - Visibility enumeration and utilities ----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// \brief Defines the clang::Visibility enumeration and various utility
14 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_BASIC_VISIBILITY_H
16 #define LLVM_CLANG_BASIC_VISIBILITY_H
18 #include "clang/Basic/Linkage.h"
22 /// \brief Describes the different kinds of visibility that a declaration
25 /// Visibility determines how a declaration interacts with the dynamic
26 /// linker. It may also affect whether the symbol can be found by runtime
27 /// symbol lookup APIs.
29 /// Visibility is not described in any language standard and
30 /// (nonetheless) sometimes has odd behavior. Not all platforms
31 /// support all visibility kinds.
33 /// Objects with "hidden" visibility are not seen by the dynamic
37 /// Objects with "protected" visibility are seen by the dynamic
38 /// linker but always dynamically resolve to an object within this
42 /// Objects with "default" visibility are seen by the dynamic linker
43 /// and act like normal objects.
47 inline Visibility minVisibility(Visibility L, Visibility R) {
53 uint8_t visibility_ : 2;
54 uint8_t explicit_ : 1;
56 void setVisibility(Visibility V, bool E) { visibility_ = V; explicit_ = E; }
58 LinkageInfo() : linkage_(ExternalLinkage), visibility_(DefaultVisibility),
60 LinkageInfo(Linkage L, Visibility V, bool E)
61 : linkage_(L), visibility_(V), explicit_(E) {
62 assert(getLinkage() == L && getVisibility() == V &&
63 isVisibilityExplicit() == E && "Enum truncated!");
66 static LinkageInfo external() {
69 static LinkageInfo internal() {
70 return LinkageInfo(InternalLinkage, DefaultVisibility, false);
72 static LinkageInfo uniqueExternal() {
73 return LinkageInfo(UniqueExternalLinkage, DefaultVisibility, false);
75 static LinkageInfo none() {
76 return LinkageInfo(NoLinkage, DefaultVisibility, false);
79 Linkage getLinkage() const { return (Linkage)linkage_; }
80 Visibility getVisibility() const { return (Visibility)visibility_; }
81 bool isVisibilityExplicit() const { return explicit_; }
83 void setLinkage(Linkage L) { linkage_ = L; }
85 void mergeLinkage(Linkage L) {
86 setLinkage(minLinkage(getLinkage(), L));
88 void mergeLinkage(LinkageInfo other) {
89 mergeLinkage(other.getLinkage());
92 /// Merge in the visibility 'newVis'.
93 void mergeVisibility(Visibility newVis, bool newExplicit) {
94 Visibility oldVis = getVisibility();
96 // Never increase visibility.
100 // If the new visibility is the same as the old and the new
101 // visibility isn't explicit, we have nothing to add.
102 if (oldVis == newVis && !newExplicit)
105 // Otherwise, we're either decreasing visibility or making our
106 // existing visibility explicit.
107 setVisibility(newVis, newExplicit);
109 void mergeVisibility(LinkageInfo other) {
110 mergeVisibility(other.getVisibility(), other.isVisibilityExplicit());
113 /// Merge both linkage and visibility.
114 void merge(LinkageInfo other) {
116 mergeVisibility(other);
119 /// Merge linkage and conditionally merge visibility.
120 void mergeMaybeWithVisibility(LinkageInfo other, bool withVis) {
122 if (withVis) mergeVisibility(other);
127 #endif // LLVM_CLANG_BASIC_VISIBILITY_H