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| Rev | Author | Line No. | Line |
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| 14 | pmbaty | 1 | //===--- Visibility.h - Visibility enumeration and utilities ----*- C++ -*-===// |
| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | /// |
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| 9 | /// \file |
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| 10 | /// Defines the clang::Visibility enumeration and various utility |
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| 11 | /// functions. |
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| 12 | /// |
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| 13 | //===----------------------------------------------------------------------===// |
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| 14 | #ifndef LLVM_CLANG_BASIC_VISIBILITY_H |
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| 15 | #define LLVM_CLANG_BASIC_VISIBILITY_H |
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| 16 | |||
| 17 | #include "clang/Basic/Linkage.h" |
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| 18 | #include <cassert> |
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| 19 | #include <cstdint> |
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| 20 | |||
| 21 | namespace clang { |
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| 22 | |||
| 23 | /// Describes the different kinds of visibility that a declaration |
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| 24 | /// may have. |
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| 25 | /// |
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| 26 | /// Visibility determines how a declaration interacts with the dynamic |
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| 27 | /// linker. It may also affect whether the symbol can be found by runtime |
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| 28 | /// symbol lookup APIs. |
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| 29 | /// |
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| 30 | /// Visibility is not described in any language standard and |
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| 31 | /// (nonetheless) sometimes has odd behavior. Not all platforms |
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| 32 | /// support all visibility kinds. |
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| 33 | enum Visibility { |
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| 34 | /// Objects with "hidden" visibility are not seen by the dynamic |
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| 35 | /// linker. |
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| 36 | HiddenVisibility, |
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| 37 | |||
| 38 | /// Objects with "protected" visibility are seen by the dynamic |
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| 39 | /// linker but always dynamically resolve to an object within this |
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| 40 | /// shared object. |
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| 41 | ProtectedVisibility, |
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| 42 | |||
| 43 | /// Objects with "default" visibility are seen by the dynamic linker |
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| 44 | /// and act like normal objects. |
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| 45 | DefaultVisibility |
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| 46 | }; |
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| 47 | |||
| 48 | inline Visibility minVisibility(Visibility L, Visibility R) { |
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| 49 | return L < R ? L : R; |
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| 50 | } |
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| 51 | |||
| 52 | class LinkageInfo { |
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| 53 | uint8_t linkage_ : 3; |
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| 54 | uint8_t visibility_ : 2; |
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| 55 | uint8_t explicit_ : 1; |
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| 56 | |||
| 57 | void setVisibility(Visibility V, bool E) { visibility_ = V; explicit_ = E; } |
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| 58 | public: |
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| 59 | LinkageInfo() : linkage_(ExternalLinkage), visibility_(DefaultVisibility), |
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| 60 | explicit_(false) {} |
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| 61 | LinkageInfo(Linkage L, Visibility V, bool E) |
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| 62 | : linkage_(L), visibility_(V), explicit_(E) { |
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| 63 | assert(getLinkage() == L && getVisibility() == V && |
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| 64 | isVisibilityExplicit() == E && "Enum truncated!"); |
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| 65 | } |
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| 66 | |||
| 67 | static LinkageInfo external() { |
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| 68 | return LinkageInfo(); |
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| 69 | } |
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| 70 | static LinkageInfo internal() { |
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| 71 | return LinkageInfo(InternalLinkage, DefaultVisibility, false); |
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| 72 | } |
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| 73 | static LinkageInfo uniqueExternal() { |
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| 74 | return LinkageInfo(UniqueExternalLinkage, DefaultVisibility, false); |
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| 75 | } |
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| 76 | static LinkageInfo none() { |
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| 77 | return LinkageInfo(NoLinkage, DefaultVisibility, false); |
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| 78 | } |
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| 79 | static LinkageInfo visible_none() { |
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| 80 | return LinkageInfo(VisibleNoLinkage, DefaultVisibility, false); |
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| 81 | } |
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| 82 | |||
| 83 | Linkage getLinkage() const { return (Linkage)linkage_; } |
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| 84 | Visibility getVisibility() const { return (Visibility)visibility_; } |
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| 85 | bool isVisibilityExplicit() const { return explicit_; } |
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| 86 | |||
| 87 | void setLinkage(Linkage L) { linkage_ = L; } |
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| 88 | |||
| 89 | void mergeLinkage(Linkage L) { |
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| 90 | setLinkage(minLinkage(getLinkage(), L)); |
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| 91 | } |
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| 92 | void mergeLinkage(LinkageInfo other) { |
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| 93 | mergeLinkage(other.getLinkage()); |
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| 94 | } |
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| 95 | |||
| 96 | void mergeExternalVisibility(Linkage L) { |
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| 97 | Linkage ThisL = getLinkage(); |
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| 98 | if (!isExternallyVisible(L)) { |
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| 99 | if (ThisL == VisibleNoLinkage) |
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| 100 | ThisL = NoLinkage; |
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| 101 | else if (ThisL == ExternalLinkage) |
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| 102 | ThisL = UniqueExternalLinkage; |
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| 103 | } |
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| 104 | setLinkage(ThisL); |
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| 105 | } |
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| 106 | void mergeExternalVisibility(LinkageInfo Other) { |
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| 107 | mergeExternalVisibility(Other.getLinkage()); |
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| 108 | } |
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| 109 | |||
| 110 | /// Merge in the visibility 'newVis'. |
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| 111 | void mergeVisibility(Visibility newVis, bool newExplicit) { |
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| 112 | Visibility oldVis = getVisibility(); |
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| 113 | |||
| 114 | // Never increase visibility. |
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| 115 | if (oldVis < newVis) |
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| 116 | return; |
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| 117 | |||
| 118 | // If the new visibility is the same as the old and the new |
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| 119 | // visibility isn't explicit, we have nothing to add. |
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| 120 | if (oldVis == newVis && !newExplicit) |
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| 121 | return; |
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| 122 | |||
| 123 | // Otherwise, we're either decreasing visibility or making our |
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| 124 | // existing visibility explicit. |
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| 125 | setVisibility(newVis, newExplicit); |
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| 126 | } |
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| 127 | void mergeVisibility(LinkageInfo other) { |
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| 128 | mergeVisibility(other.getVisibility(), other.isVisibilityExplicit()); |
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| 129 | } |
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| 130 | |||
| 131 | /// Merge both linkage and visibility. |
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| 132 | void merge(LinkageInfo other) { |
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| 133 | mergeLinkage(other); |
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| 134 | mergeVisibility(other); |
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| 135 | } |
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| 136 | |||
| 137 | /// Merge linkage and conditionally merge visibility. |
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| 138 | void mergeMaybeWithVisibility(LinkageInfo other, bool withVis) { |
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| 139 | mergeLinkage(other); |
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| 140 | if (withVis) mergeVisibility(other); |
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| 141 | } |
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| 142 | }; |
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| 143 | } |
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| 144 | |||
| 145 | #endif // LLVM_CLANG_BASIC_VISIBILITY_H |