1 //===-- llvm/Support/Compiler.h - Compiler abstraction support --*- 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 // This file defines several macros, based on the current compiler. This allows 11 // use of compiler-specific features in a way that remains portable. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_SUPPORT_COMPILER_H 16 #define LLVM_SUPPORT_COMPILER_H 17 18 #ifndef __has_feature 19 # define __has_feature(x) 0 20 #endif 21 22 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked 23 /// into a shared library, then the class should be private to the library and 24 /// not accessible from outside it. Can also be used to mark variables and 25 /// functions, making them private to any shared library they are linked into. 26 #if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__) 27 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden"))) 28 #else 29 #define LLVM_LIBRARY_VISIBILITY 30 #endif 31 32 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)) 33 #define LLVM_ATTRIBUTE_USED __attribute__((__used__)) 34 #else 35 #define LLVM_ATTRIBUTE_USED 36 #endif 37 38 // Some compilers warn about unused functions. When a function is sometimes 39 // used or not depending on build settings (e.g. a function only called from 40 // within "assert"), this attribute can be used to suppress such warnings. 41 // 42 // However, it shouldn't be used for unused *variables*, as those have a much 43 // more portable solution: 44 // (void)unused_var_name; 45 // Prefer cast-to-void wherever it is sufficient. 46 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1)) 47 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__)) 48 #else 49 #define LLVM_ATTRIBUTE_UNUSED 50 #endif 51 52 #if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__) 53 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__)) 54 #else 55 #define LLVM_ATTRIBUTE_WEAK 56 #endif 57 58 #ifdef __GNUC__ // aka 'CONST' but following LLVM Conventions. 59 #define LLVM_READNONE __attribute__((__const__)) 60 #else 61 #define LLVM_READNONE 62 #endif 63 64 #ifdef __GNUC__ // aka 'PURE' but following LLVM Conventions. 65 #define LLVM_READONLY __attribute__((__pure__)) 66 #else 67 #define LLVM_READONLY 68 #endif 69 70 #if (__GNUC__ >= 4) 71 #define BUILTIN_EXPECT(EXPR, VALUE) __builtin_expect((EXPR), (VALUE)) 72 #else 73 #define BUILTIN_EXPECT(EXPR, VALUE) (EXPR) 74 #endif 75 76 77 // C++ doesn't support 'extern template' of template specializations. GCC does, 78 // but requires __extension__ before it. In the header, use this: 79 // EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>); 80 // in the .cpp file, use this: 81 // TEMPLATE_INSTANTIATION(class foo<bar>); 82 #ifdef __GNUC__ 83 #define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X 84 #define TEMPLATE_INSTANTIATION(X) template X 85 #else 86 #define EXTERN_TEMPLATE_INSTANTIATION(X) 87 #define TEMPLATE_INSTANTIATION(X) 88 #endif 89 90 // LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so, 91 // mark a method "not for inlining". 92 #if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)) 93 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline)) 94 #elif defined(_MSC_VER) 95 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline) 96 #else 97 #define LLVM_ATTRIBUTE_NOINLINE 98 #endif 99 100 // LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do 101 // so, mark a method "always inline" because it is performance sensitive. GCC 102 // 3.4 supported this but is buggy in various cases and produces unimplemented 103 // errors, just use it in GCC 4.0 and later. 104 #if __GNUC__ > 3 105 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __attribute__((always_inline)) 106 #elif defined(_MSC_VER) 107 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline 108 #else 109 #define LLVM_ATTRIBUTE_ALWAYS_INLINE 110 #endif 111 112 113 #ifdef __GNUC__ 114 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn)) 115 #elif defined(_MSC_VER) 116 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn) 117 #else 118 #define LLVM_ATTRIBUTE_NORETURN 119 #endif 120 121 // LLVM_EXTENSION - Support compilers where we have a keyword to suppress 122 // pedantic diagnostics. 123 #ifdef __GNUC__ 124 #define LLVM_EXTENSION __extension__ 125 #else 126 #define LLVM_EXTENSION 127 #endif 128 129 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message") 130 #if __has_feature(attribute_deprecated_with_message) 131 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 132 decl __attribute__((deprecated(message))) 133 #elif defined(__GNUC__) 134 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 135 decl __attribute__((deprecated)) 136 #elif defined(_MSC_VER) 137 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 138 __declspec(deprecated(message)) decl 139 #else 140 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \ 141 decl 142 #endif 143 144 // LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands 145 // to an expression which states that it is undefined behavior for the 146 // compiler to reach this point. Otherwise is not defined. 147 #if defined(__clang__) || (__GNUC__ > 4) \ 148 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5) 149 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable() 150 #endif 151 152 #endif 153
