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__) \
27 || (defined(_MSC_VER) && _MSC_VER >= 1600))
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_DELETED_FUNCTION - Expands to = delete if the compiler supports it.
42 /// Use to mark functions as uncallable. Member functions with this should
43 /// be declared private so that some behavior is kept in C++03 mode.
47 /// DontCopy(const DontCopy&) LLVM_DELETED_FUNCTION;
48 /// DontCopy &operator =(const DontCopy&) LLVM_DELETED_FUNCTION;
52 #if (__has_feature(cxx_deleted_functions) \
53 || defined(__GXX_EXPERIMENTAL_CXX0X__))
54 // No version of MSVC currently supports this.
55 #define LLVM_DELETED_FUNCTION = delete
57 #define LLVM_DELETED_FUNCTION
60 /// LLVM_FINAL - Expands to 'final' if the compiler supports it.
61 /// Use to mark classes or virtual methods as final.
62 #if (__has_feature(cxx_override_control))
63 #define LLVM_FINAL final
68 /// LLVM_OVERRIDE - Expands to 'override' if the compiler supports it.
69 /// Use to mark virtual methods as overriding a base class method.
70 #if (__has_feature(cxx_override_control))
71 #define LLVM_OVERRIDE override
76 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked
77 /// into a shared library, then the class should be private to the library and
78 /// not accessible from outside it. Can also be used to mark variables and
79 /// functions, making them private to any shared library they are linked into.
80 #if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
81 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
83 #define LLVM_LIBRARY_VISIBILITY
86 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
87 #define LLVM_ATTRIBUTE_USED __attribute__((__used__))
89 #define LLVM_ATTRIBUTE_USED
92 // Some compilers warn about unused functions. When a function is sometimes
93 // used or not depending on build settings (e.g. a function only called from
94 // within "assert"), this attribute can be used to suppress such warnings.
96 // However, it shouldn't be used for unused *variables*, as those have a much
97 // more portable solution:
98 // (void)unused_var_name;
99 // Prefer cast-to-void wherever it is sufficient.
100 #if (__GNUC__ >= 4 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 1))
101 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
103 #define LLVM_ATTRIBUTE_UNUSED
106 #if (__GNUC__ >= 4) && !defined(__MINGW32__) && !defined(__CYGWIN__)
107 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
109 #define LLVM_ATTRIBUTE_WEAK
112 #ifdef __GNUC__ // aka 'CONST' but following LLVM Conventions.
113 #define LLVM_READNONE __attribute__((__const__))
115 #define LLVM_READNONE
118 #ifdef __GNUC__ // aka 'PURE' but following LLVM Conventions.
119 #define LLVM_READONLY __attribute__((__pure__))
121 #define LLVM_READONLY
125 #define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true)
126 #define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false)
128 #define LLVM_LIKELY(EXPR) (EXPR)
129 #define LLVM_UNLIKELY(EXPR) (EXPR)
133 // C++ doesn't support 'extern template' of template specializations. GCC does,
134 // but requires __extension__ before it. In the header, use this:
135 // EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>);
136 // in the .cpp file, use this:
137 // TEMPLATE_INSTANTIATION(class foo<bar>);
139 #define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X
140 #define TEMPLATE_INSTANTIATION(X) template X
142 #define EXTERN_TEMPLATE_INSTANTIATION(X)
143 #define TEMPLATE_INSTANTIATION(X)
146 // LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
147 // mark a method "not for inlining".
148 #if (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
149 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
150 #elif defined(_MSC_VER)
151 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
153 #define LLVM_ATTRIBUTE_NOINLINE
156 // LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do
157 // so, mark a method "always inline" because it is performance sensitive. GCC
158 // 3.4 supported this but is buggy in various cases and produces unimplemented
159 // errors, just use it in GCC 4.0 and later.
161 #define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline))
162 #elif defined(_MSC_VER)
163 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
165 #define LLVM_ATTRIBUTE_ALWAYS_INLINE
170 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn))
171 #elif defined(_MSC_VER)
172 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn)
174 #define LLVM_ATTRIBUTE_NORETURN
177 // LLVM_EXTENSION - Support compilers where we have a keyword to suppress
178 // pedantic diagnostics.
180 #define LLVM_EXTENSION __extension__
182 #define LLVM_EXTENSION
185 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message")
186 #if __has_feature(attribute_deprecated_with_message)
187 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
188 decl __attribute__((deprecated(message)))
189 #elif defined(__GNUC__)
190 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
191 decl __attribute__((deprecated))
192 #elif defined(_MSC_VER)
193 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
194 __declspec(deprecated(message)) decl
196 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
200 // LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
201 // to an expression which states that it is undefined behavior for the
202 // compiler to reach this point. Otherwise is not defined.
203 #if defined(__clang__) || (__GNUC__ > 4) \
204 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
205 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
208 // LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression
209 // which causes the program to exit abnormally.
210 #if defined(__clang__) || (__GNUC__ > 4) \
211 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)
212 # define LLVM_BUILTIN_TRAP __builtin_trap()
214 # define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0