1 //===--- Linkage.h - Linkage 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 Linkage enumeration and various utility functions. 12 /// 13 //===----------------------------------------------------------------------===// 14 #ifndef LLVM_CLANG_BASIC_LINKAGE_H 15 #define LLVM_CLANG_BASIC_LINKAGE_H 16 17 namespace clang { 18 19 /// \brief Describes the different kinds of linkage 20 /// (C++ [basic.link], C99 6.2.2) that an entity may have. 21 enum Linkage { 22 /// \brief No linkage, which means that the entity is unique and 23 /// can only be referred to from within its scope. 24 NoLinkage = 0, 25 26 /// \brief Internal linkage, which indicates that the entity can 27 /// be referred to from within the translation unit (but not other 28 /// translation units). 29 InternalLinkage, 30 31 /// \brief External linkage within a unique namespace. 32 /// 33 /// From the language perspective, these entities have external 34 /// linkage. However, since they reside in an anonymous namespace, 35 /// their names are unique to this translation unit, which is 36 /// equivalent to having internal linkage from the code-generation 37 /// point of view. 38 UniqueExternalLinkage, 39 40 /// \brief No linkage according to the standard, but is visible from other 41 /// translation units because of types defined in a inline function. 42 VisibleNoLinkage, 43 44 /// \brief External linkage, which indicates that the entity can 45 /// be referred to from other translation units. 46 ExternalLinkage 47 }; 48 49 /// \brief Describes the different kinds of language linkage 50 /// (C++ [dcl.link]) that an entity may have. 51 enum LanguageLinkage { 52 CLanguageLinkage, 53 CXXLanguageLinkage, 54 NoLanguageLinkage 55 }; 56 57 /// \brief A more specific kind of linkage than enum Linkage. 58 /// 59 /// This is relevant to CodeGen and AST file reading. 60 enum GVALinkage { 61 GVA_Internal, 62 GVA_C99Inline, 63 GVA_CXXInline, 64 GVA_StrongExternal, 65 GVA_TemplateInstantiation, 66 GVA_ExplicitTemplateInstantiation 67 }; 68 69 inline bool isExternallyVisible(Linkage L) { 70 return L == ExternalLinkage || L == VisibleNoLinkage; 71 } 72 73 inline Linkage getFormalLinkage(Linkage L) { 74 if (L == UniqueExternalLinkage) 75 return ExternalLinkage; 76 if (L == VisibleNoLinkage) 77 return NoLinkage; 78 return L; 79 } 80 81 inline bool isExternalFormalLinkage(Linkage L) { 82 return getFormalLinkage(L) == ExternalLinkage; 83 } 84 85 /// \brief Compute the minimum linkage given two linkages. 86 /// 87 /// The linkage can be interpreted as a pair formed by the formal linkage and 88 /// a boolean for external visibility. This is just what getFormalLinkage and 89 /// isExternallyVisible return. We want the minimum of both components. The 90 /// Linkage enum is defined in an order that makes this simple, we just need 91 /// special cases for when VisibleNoLinkage would lose the visible bit and 92 /// become NoLinkage. 93 inline Linkage minLinkage(Linkage L1, Linkage L2) { 94 if (L2 == VisibleNoLinkage) 95 std::swap(L1, L2); 96 if (L1 == VisibleNoLinkage) { 97 if (L2 == InternalLinkage) 98 return NoLinkage; 99 if (L2 == UniqueExternalLinkage) 100 return NoLinkage; 101 } 102 return L1 < L2 ? L1 : L2; 103 } 104 105 } // end namespace clang 106 107 #endif // LLVM_CLANG_BASIC_LINKAGE_H 108
