1 //===-- llvm/Support/Compiler.h - Compiler abstraction support --*- 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 //===----------------------------------------------------------------------===//
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.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_SUPPORT_COMPILER_H
16 #define LLVM_SUPPORT_COMPILER_H
18 // The VISIBILITY_HIDDEN macro, used for marking classes with the GCC-specific
19 // visibility("hidden") attribute.
20 #if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
21 #define VISIBILITY_HIDDEN __attribute__ ((visibility("hidden")))
23 #define VISIBILITY_HIDDEN
26 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
27 #define ATTRIBUTE_USED __attribute__((__used__))
29 #define ATTRIBUTE_USED
32 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
33 #define ATTRIBUTE_UNUSED __attribute__((__unused__))
35 #define ATTRIBUTE_UNUSED
38 #ifdef __GNUC__ // aka 'ATTRIBUTE_CONST' but following LLVM Conventions.
39 #define ATTRIBUTE_READNONE __attribute__((__const__))
41 #define ATTRIBUTE_READNONE
44 #ifdef __GNUC__ // aka 'ATTRIBUTE_PURE' but following LLVM Conventions.
45 #define ATTRIBUTE_READONLY __attribute__((__pure__))
47 #define ATTRIBUTE_READONLY
51 #define BUILTIN_EXPECT(EXPR, VALUE) __builtin_expect((EXPR), (VALUE))
53 #define BUILTIN_EXPECT(EXPR, VALUE) (EXPR)
56 // C++ doesn't support 'extern template' of template specializations. GCC does,
57 // but requires __extension__ before it. In the header, use this:
58 // EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>);
59 // in the .cpp file, use this:
60 // TEMPLATE_INSTANTIATION(class foo<bar>);
62 #define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X
63 #define TEMPLATE_INSTANTIATION(X) template X
65 #define EXTERN_TEMPLATE_INSTANTIATION(X)
66 #define TEMPLATE_INSTANTIATION(X)
69 // DISABLE_INLINE - On compilers where we have a directive to do so, mark a
70 // method "not for inlining".
71 #if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
72 #define DISABLE_INLINE __attribute__((noinline))
73 #elif defined(_MSC_VER)
74 #define DISABLE_INLINE __declspec(noinline)
76 #define DISABLE_INLINE
79 // ALWAYS_INLINE - On compilers where we have a directive to do so, mark a
80 // method "always inline" because it is performance sensitive.
81 #if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
82 #define ALWAYS_INLINE __attribute__((always_inline))
84 // TODO: No idea how to do this with MSVC.
90 #define NORETURN __attribute__((noreturn))
91 #elif defined(_MSC_VER)
92 #define NORETURN __declspec(noreturn)