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 #include "llvm/Config/llvm-config.h"
21 # define __has_feature(x) 0
24 #ifndef __has_extension
25 # define __has_extension(x) 0
28 #ifndef __has_attribute
29 # define __has_attribute(x) 0
33 # define __has_builtin(x) 0
36 /// \macro __GNUC_PREREQ
37 /// \brief Defines __GNUC_PREREQ if glibc's features.h isn't available.
39 # if defined(__GNUC__) && defined(__GNUC_MINOR__)
40 # define __GNUC_PREREQ(maj, min) \
41 ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
43 # define __GNUC_PREREQ(maj, min) 0
47 /// \macro LLVM_MSC_PREREQ
48 /// \brief Is the compiler MSVC of at least the specified version?
49 /// The common \param version values to check for are:
50 /// * 1700: Microsoft Visual Studio 2012 / 11.0
51 /// * 1800: Microsoft Visual Studio 2013 / 12.0
53 #define LLVM_MSC_PREREQ(version) (_MSC_VER >= (version))
55 // We require at least MSVC 2012.
56 #if !LLVM_MSC_PREREQ(1700)
57 #error LLVM requires at least MSVC 2012.
61 #define LLVM_MSC_PREREQ(version) 0
65 #define LLVM_NOEXCEPT noexcept
70 /// \brief Does the compiler support r-value reference *this?
72 /// Sadly, this is separate from just r-value reference support because GCC
73 /// implemented everything but this thus far. No release of GCC yet has support
74 /// for this feature so it is enabled with Clang only.
75 /// FIXME: This should change to a version check when GCC grows support for it.
76 #if __has_feature(cxx_rvalue_references)
77 #define LLVM_HAS_RVALUE_REFERENCE_THIS 1
79 #define LLVM_HAS_RVALUE_REFERENCE_THIS 0
82 /// \macro LLVM_HAS_VARIADIC_TEMPLATES
83 /// \brief Does this compiler support variadic templates.
85 /// Implies LLVM_HAS_RVALUE_REFERENCES and the existence of std::forward.
86 #if __has_feature(cxx_variadic_templates) || LLVM_MSC_PREREQ(1800)
87 # define LLVM_HAS_VARIADIC_TEMPLATES 1
89 # define LLVM_HAS_VARIADIC_TEMPLATES 0
92 /// Expands to '&' if r-value references are supported.
94 /// This can be used to provide l-value/r-value overrides of member functions.
95 /// The r-value override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS
96 #if LLVM_HAS_RVALUE_REFERENCE_THIS
97 #define LLVM_LVALUE_FUNCTION &
99 #define LLVM_LVALUE_FUNCTION
102 /// LLVM_DELETED_FUNCTION - Expands to = delete if the compiler supports it.
103 /// Use to mark functions as uncallable. Member functions with this should
104 /// be declared private so that some behavior is kept in C++03 mode.
108 /// DontCopy(const DontCopy&) LLVM_DELETED_FUNCTION;
109 /// DontCopy &operator =(const DontCopy&) LLVM_DELETED_FUNCTION;
113 #if __has_feature(cxx_deleted_functions) || \
114 defined(__GXX_EXPERIMENTAL_CXX0X__) || LLVM_MSC_PREREQ(1800)
115 #define LLVM_DELETED_FUNCTION = delete
117 #define LLVM_DELETED_FUNCTION
120 #if __has_feature(cxx_constexpr) || defined(__GXX_EXPERIMENTAL_CXX0X__)
121 # define LLVM_CONSTEXPR constexpr
123 # define LLVM_CONSTEXPR
126 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked
127 /// into a shared library, then the class should be private to the library and
128 /// not accessible from outside it. Can also be used to mark variables and
129 /// functions, making them private to any shared library they are linked into.
130 /// On PE/COFF targets, library visibility is the default, so this isn't needed.
131 #if (__has_attribute(visibility) || __GNUC_PREREQ(4, 0)) && \
132 !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32)
133 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
135 #define LLVM_LIBRARY_VISIBILITY
138 #if __has_attribute(used) || __GNUC_PREREQ(3, 1)
139 #define LLVM_ATTRIBUTE_USED __attribute__((__used__))
141 #define LLVM_ATTRIBUTE_USED
144 #if __has_attribute(warn_unused_result) || __GNUC_PREREQ(3, 4)
145 #define LLVM_ATTRIBUTE_UNUSED_RESULT __attribute__((__warn_unused_result__))
147 #define LLVM_ATTRIBUTE_UNUSED_RESULT
150 // Some compilers warn about unused functions. When a function is sometimes
151 // used or not depending on build settings (e.g. a function only called from
152 // within "assert"), this attribute can be used to suppress such warnings.
154 // However, it shouldn't be used for unused *variables*, as those have a much
155 // more portable solution:
156 // (void)unused_var_name;
157 // Prefer cast-to-void wherever it is sufficient.
158 #if __has_attribute(unused) || __GNUC_PREREQ(3, 1)
159 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
161 #define LLVM_ATTRIBUTE_UNUSED
164 // FIXME: Provide this for PE/COFF targets.
165 #if (__has_attribute(weak) || __GNUC_PREREQ(4, 0)) && \
166 (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32))
167 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
169 #define LLVM_ATTRIBUTE_WEAK
172 // Prior to clang 3.2, clang did not accept any spelling of
173 // __has_attribute(const), so assume it is supported.
174 #if defined(__clang__) || defined(__GNUC__)
175 // aka 'CONST' but following LLVM Conventions.
176 #define LLVM_READNONE __attribute__((__const__))
178 #define LLVM_READNONE
181 #if __has_attribute(pure) || defined(__GNUC__)
182 // aka 'PURE' but following LLVM Conventions.
183 #define LLVM_READONLY __attribute__((__pure__))
185 #define LLVM_READONLY
188 #if __has_builtin(__builtin_expect) || __GNUC_PREREQ(4, 0)
189 #define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true)
190 #define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false)
192 #define LLVM_LIKELY(EXPR) (EXPR)
193 #define LLVM_UNLIKELY(EXPR) (EXPR)
196 // C++ doesn't support 'extern template' of template specializations. GCC does,
197 // but requires __extension__ before it. In the header, use this:
198 // EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>);
199 // in the .cpp file, use this:
200 // TEMPLATE_INSTANTIATION(class foo<bar>);
202 #define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X
203 #define TEMPLATE_INSTANTIATION(X) template X
205 #define EXTERN_TEMPLATE_INSTANTIATION(X)
206 #define TEMPLATE_INSTANTIATION(X)
209 /// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
210 /// mark a method "not for inlining".
211 #if __has_attribute(noinline) || __GNUC_PREREQ(3, 4)
212 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
213 #elif defined(_MSC_VER)
214 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
216 #define LLVM_ATTRIBUTE_NOINLINE
219 /// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do
220 /// so, mark a method "always inline" because it is performance sensitive. GCC
221 /// 3.4 supported this but is buggy in various cases and produces unimplemented
222 /// errors, just use it in GCC 4.0 and later.
223 #if __has_attribute(always_inline) || __GNUC_PREREQ(4, 0)
224 #define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline))
225 #elif defined(_MSC_VER)
226 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
228 #define LLVM_ATTRIBUTE_ALWAYS_INLINE
232 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn))
233 #elif defined(_MSC_VER)
234 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn)
236 #define LLVM_ATTRIBUTE_NORETURN
239 /// LLVM_EXTENSION - Support compilers where we have a keyword to suppress
240 /// pedantic diagnostics.
242 #define LLVM_EXTENSION __extension__
244 #define LLVM_EXTENSION
247 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message")
248 #if __has_feature(attribute_deprecated_with_message)
249 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
250 decl __attribute__((deprecated(message)))
251 #elif defined(__GNUC__)
252 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
253 decl __attribute__((deprecated))
254 #elif defined(_MSC_VER)
255 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
256 __declspec(deprecated(message)) decl
258 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
262 /// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
263 /// to an expression which states that it is undefined behavior for the
264 /// compiler to reach this point. Otherwise is not defined.
265 #if __has_builtin(__builtin_unreachable) || __GNUC_PREREQ(4, 5)
266 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
267 #elif defined(_MSC_VER)
268 # define LLVM_BUILTIN_UNREACHABLE __assume(false)
271 /// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression
272 /// which causes the program to exit abnormally.
273 #if __has_builtin(__builtin_trap) || __GNUC_PREREQ(4, 3)
274 # define LLVM_BUILTIN_TRAP __builtin_trap()
276 # define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0
279 /// \macro LLVM_ASSUME_ALIGNED
280 /// \brief Returns a pointer with an assumed alignment.
281 #if __has_builtin(__builtin_assume_aligned) && __GNUC_PREREQ(4, 7)
282 # define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a)
283 #elif defined(LLVM_BUILTIN_UNREACHABLE)
284 // As of today, clang does not support __builtin_assume_aligned.
285 # define LLVM_ASSUME_ALIGNED(p, a) \
286 (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p)))
288 # define LLVM_ASSUME_ALIGNED(p, a) (p)
291 /// \macro LLVM_FUNCTION_NAME
292 /// \brief Expands to __func__ on compilers which support it. Otherwise,
293 /// expands to a compiler-dependent replacement.
294 #if defined(_MSC_VER)
295 # define LLVM_FUNCTION_NAME __FUNCTION__
297 # define LLVM_FUNCTION_NAME __func__
300 /// \macro LLVM_MEMORY_SANITIZER_BUILD
301 /// \brief Whether LLVM itself is built with MemorySanitizer instrumentation.
302 #if __has_feature(memory_sanitizer)
303 # define LLVM_MEMORY_SANITIZER_BUILD 1
304 # include <sanitizer/msan_interface.h>
306 # define LLVM_MEMORY_SANITIZER_BUILD 0
307 # define __msan_allocated_memory(p, size)
308 # define __msan_unpoison(p, size)
311 /// \macro LLVM_ADDRESS_SANITIZER_BUILD
312 /// \brief Whether LLVM itself is built with AddressSanitizer instrumentation.
313 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
314 # define LLVM_ADDRESS_SANITIZER_BUILD 1
316 # define LLVM_ADDRESS_SANITIZER_BUILD 0
319 /// \macro LLVM_IS_UNALIGNED_ACCESS_FAST
320 /// \brief Is unaligned memory access fast on the host machine.
322 /// Don't specialize on alignment for platforms where unaligned memory accesses
323 /// generates the same code as aligned memory accesses for common types.
324 #if defined(_M_AMD64) || defined(_M_IX86) || defined(__amd64) || \
325 defined(__amd64__) || defined(__x86_64) || defined(__x86_64__) || \
326 defined(_X86_) || defined(__i386) || defined(__i386__)
327 # define LLVM_IS_UNALIGNED_ACCESS_FAST 1
329 # define LLVM_IS_UNALIGNED_ACCESS_FAST 0
332 /// \macro LLVM_EXPLICIT
333 /// \brief Expands to explicit on compilers which support explicit conversion
334 /// operators. Otherwise expands to nothing.
335 #if __has_feature(cxx_explicit_conversions) || \
336 defined(__GXX_EXPERIMENTAL_CXX0X__) || LLVM_MSC_PREREQ(1800)
337 #define LLVM_EXPLICIT explicit
339 #define LLVM_EXPLICIT
342 /// \brief Does the compiler support generalized initializers (using braced
343 /// lists and std::initializer_list). While clang may claim it supports general
344 /// initializers, if we're using MSVC's headers, we might not have a usable
345 /// std::initializer list type from the STL. Disable this for now.
346 #if __has_feature(cxx_generalized_initializers) && !defined(_MSC_VER)
347 #define LLVM_HAS_INITIALIZER_LISTS 1
349 #define LLVM_HAS_INITIALIZER_LISTS 0
352 /// \brief Mark debug helper function definitions like dump() that should not be
353 /// stripped from debug builds.
354 // FIXME: Move this to a private config.h as it's not usable in public headers.
355 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
356 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED
358 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE