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
19 # define __has_feature(x) 0
22 /// LLVM_HAS_RVALUE_REFERENCES - Does the compiler provide r-value references?
23 /// This implies that <utility> provides the one-argument std::move; it
24 /// does not imply the existence of any other C++ library features.
25 #if (__has_feature(cxx_rvalue_references) \
26 || defined(__GXX_EXPERIMENTAL_CXX0X__) \
28 #define LLVM_USE_RVALUE_REFERENCES 1
30 #define LLVM_USE_RVALUE_REFERENCES 0
33 /// llvm_move - Expands to ::std::move if the compiler supports
34 /// r-value references; otherwise, expands to the argument.
35 #if LLVM_USE_RVALUE_REFERENCES
36 #define llvm_move(value) (::std::move(value))
38 #define llvm_move(value) (value)
41 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked
42 /// into a shared library, then the class should be private to the library and
43 /// not accessible from outside it. Can also be used to mark variables and
44 /// functions, making them private to any shared library they are linked into.
45 #if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
46 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
48 #define LLVM_LIBRARY_VISIBILITY
51 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
52 #define LLVM_ATTRIBUTE_USED __attribute__((__used__))
54 #define LLVM_ATTRIBUTE_USED
57 // Some compilers warn about unused functions. When a function is sometimes
58 // used or not depending on build settings (e.g. a function only called from
59 // within "assert"), this attribute can be used to suppress such warnings.
61 // However, it shouldn't be used for unused *variables*, as those have a much
62 // more portable solution:
63 // (void)unused_var_name;
64 // Prefer cast-to-void wherever it is sufficient.
65 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
66 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
68 #define LLVM_ATTRIBUTE_UNUSED
71 #if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
72 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
74 #define LLVM_ATTRIBUTE_WEAK
77 #ifdef __GNUC__ // aka 'CONST' but following LLVM Conventions.
78 #define LLVM_READNONE __attribute__((__const__))
83 #ifdef __GNUC__ // aka 'PURE' but following LLVM Conventions.
84 #define LLVM_READONLY __attribute__((__pure__))
90 #define BUILTIN_EXPECT(EXPR, VALUE) __builtin_expect((EXPR), (VALUE))
92 #define BUILTIN_EXPECT(EXPR, VALUE) (EXPR)
96 // C++ doesn't support 'extern template' of template specializations. GCC does,
97 // but requires __extension__ before it. In the header, use this:
98 // EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>);
99 // in the .cpp file, use this:
100 // TEMPLATE_INSTANTIATION(class foo<bar>);
102 #define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X
103 #define TEMPLATE_INSTANTIATION(X) template X
105 #define EXTERN_TEMPLATE_INSTANTIATION(X)
106 #define TEMPLATE_INSTANTIATION(X)
109 // LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
110 // mark a method "not for inlining".
111 #if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
112 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
113 #elif defined(_MSC_VER)
114 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
116 #define LLVM_ATTRIBUTE_NOINLINE
119 // LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do
120 // so, mark a method "always inline" because it is performance sensitive. GCC
121 // 3.4 supported this but is buggy in various cases and produces unimplemented
122 // errors, just use it in GCC 4.0 and later.
124 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __attribute__((always_inline))
125 #elif defined(_MSC_VER)
126 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
128 #define LLVM_ATTRIBUTE_ALWAYS_INLINE
133 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn))
134 #elif defined(_MSC_VER)
135 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn)
137 #define LLVM_ATTRIBUTE_NORETURN
140 // LLVM_EXTENSION - Support compilers where we have a keyword to suppress
141 // pedantic diagnostics.
143 #define LLVM_EXTENSION __extension__
145 #define LLVM_EXTENSION
148 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message")
149 #if __has_feature(attribute_deprecated_with_message)
150 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
151 decl __attribute__((deprecated(message)))
152 #elif defined(__GNUC__)
153 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
154 decl __attribute__((deprecated))
155 #elif defined(_MSC_VER)
156 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
157 __declspec(deprecated(message)) decl
159 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
163 // LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
164 // to an expression which states that it is undefined behavior for the
165 // compiler to reach this point. Otherwise is not defined.
166 #if defined(__clang__) || (__GNUC__ > 4) \
167 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
168 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()