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
64 /// \brief Does the compiler support r-value reference *this?
66 /// Sadly, this is separate from just r-value reference support because GCC
67 /// implemented everything but this thus far. No release of GCC yet has support
68 /// for this feature so it is enabled with Clang only.
69 /// FIXME: This should change to a version check when GCC grows support for it.
70 #if __has_feature(cxx_rvalue_references)
71 #define LLVM_HAS_RVALUE_REFERENCE_THIS 1
73 #define LLVM_HAS_RVALUE_REFERENCE_THIS 0
76 /// \macro LLVM_HAS_VARIADIC_TEMPLATES
77 /// \brief Does this compiler support variadic templates.
79 /// Implies LLVM_HAS_RVALUE_REFERENCES and the existence of std::forward.
80 #if __has_feature(cxx_variadic_templates) || LLVM_MSC_PREREQ(1800)
81 # define LLVM_HAS_VARIADIC_TEMPLATES 1
83 # define LLVM_HAS_VARIADIC_TEMPLATES 0
86 /// Expands to '&' if r-value references are supported.
88 /// This can be used to provide l-value/r-value overrides of member functions.
89 /// The r-value override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS
90 #if LLVM_HAS_RVALUE_REFERENCE_THIS
91 #define LLVM_LVALUE_FUNCTION &
93 #define LLVM_LVALUE_FUNCTION
96 /// LLVM_DELETED_FUNCTION - Expands to = delete if the compiler supports it.
97 /// Use to mark functions as uncallable. Member functions with this should
98 /// be declared private so that some behavior is kept in C++03 mode.
102 /// DontCopy(const DontCopy&) LLVM_DELETED_FUNCTION;
103 /// DontCopy &operator =(const DontCopy&) LLVM_DELETED_FUNCTION;
107 #if __has_feature(cxx_deleted_functions) || LLVM_MSC_PREREQ(1800)
108 #define LLVM_DELETED_FUNCTION = delete
110 #define LLVM_DELETED_FUNCTION
113 #if __has_feature(cxx_constexpr)
114 # define LLVM_CONSTEXPR constexpr
116 # define LLVM_CONSTEXPR
119 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked
120 /// into a shared library, then the class should be private to the library and
121 /// not accessible from outside it. Can also be used to mark variables and
122 /// functions, making them private to any shared library they are linked into.
123 /// On PE/COFF targets, library visibility is the default, so this isn't needed.
124 #if (__has_attribute(visibility) || __GNUC_PREREQ(4, 0)) && \
125 !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32)
126 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
128 #define LLVM_LIBRARY_VISIBILITY
131 #if __has_attribute(used) || __GNUC_PREREQ(3, 1)
132 #define LLVM_ATTRIBUTE_USED __attribute__((__used__))
134 #define LLVM_ATTRIBUTE_USED
137 #if __has_attribute(warn_unused_result) || __GNUC_PREREQ(3, 4)
138 #define LLVM_ATTRIBUTE_UNUSED_RESULT __attribute__((__warn_unused_result__))
140 #define LLVM_ATTRIBUTE_UNUSED_RESULT
143 // Some compilers warn about unused functions. When a function is sometimes
144 // used or not depending on build settings (e.g. a function only called from
145 // within "assert"), this attribute can be used to suppress such warnings.
147 // However, it shouldn't be used for unused *variables*, as those have a much
148 // more portable solution:
149 // (void)unused_var_name;
150 // Prefer cast-to-void wherever it is sufficient.
151 #if __has_attribute(unused) || __GNUC_PREREQ(3, 1)
152 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
154 #define LLVM_ATTRIBUTE_UNUSED
157 // FIXME: Provide this for PE/COFF targets.
158 #if (__has_attribute(weak) || __GNUC_PREREQ(4, 0)) && \
159 (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32))
160 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
162 #define LLVM_ATTRIBUTE_WEAK
165 // Prior to clang 3.2, clang did not accept any spelling of
166 // __has_attribute(const), so assume it is supported.
167 #if defined(__clang__) || defined(__GNUC__)
168 // aka 'CONST' but following LLVM Conventions.
169 #define LLVM_READNONE __attribute__((__const__))
171 #define LLVM_READNONE
174 #if __has_attribute(pure) || defined(__GNUC__)
175 // aka 'PURE' but following LLVM Conventions.
176 #define LLVM_READONLY __attribute__((__pure__))
178 #define LLVM_READONLY
181 #if __has_builtin(__builtin_expect) || __GNUC_PREREQ(4, 0)
182 #define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true)
183 #define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false)
185 #define LLVM_LIKELY(EXPR) (EXPR)
186 #define LLVM_UNLIKELY(EXPR) (EXPR)
189 // C++ doesn't support 'extern template' of template specializations. GCC does,
190 // but requires __extension__ before it. In the header, use this:
191 // EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>);
192 // in the .cpp file, use this:
193 // TEMPLATE_INSTANTIATION(class foo<bar>);
195 #define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X
196 #define TEMPLATE_INSTANTIATION(X) template X
198 #define EXTERN_TEMPLATE_INSTANTIATION(X)
199 #define TEMPLATE_INSTANTIATION(X)
202 /// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
203 /// mark a method "not for inlining".
204 #if __has_attribute(noinline) || __GNUC_PREREQ(3, 4)
205 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
206 #elif defined(_MSC_VER)
207 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
209 #define LLVM_ATTRIBUTE_NOINLINE
212 /// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do
213 /// so, mark a method "always inline" because it is performance sensitive. GCC
214 /// 3.4 supported this but is buggy in various cases and produces unimplemented
215 /// errors, just use it in GCC 4.0 and later.
216 #if __has_attribute(always_inline) || __GNUC_PREREQ(4, 0)
217 #define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline))
218 #elif defined(_MSC_VER)
219 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
221 #define LLVM_ATTRIBUTE_ALWAYS_INLINE
225 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn))
226 #elif defined(_MSC_VER)
227 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn)
229 #define LLVM_ATTRIBUTE_NORETURN
232 /// LLVM_EXTENSION - Support compilers where we have a keyword to suppress
233 /// pedantic diagnostics.
235 #define LLVM_EXTENSION __extension__
237 #define LLVM_EXTENSION
240 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message")
241 #if __has_feature(attribute_deprecated_with_message)
242 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
243 decl __attribute__((deprecated(message)))
244 #elif defined(__GNUC__)
245 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
246 decl __attribute__((deprecated))
247 #elif defined(_MSC_VER)
248 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
249 __declspec(deprecated(message)) decl
251 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
255 /// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
256 /// to an expression which states that it is undefined behavior for the
257 /// compiler to reach this point. Otherwise is not defined.
258 #if __has_builtin(__builtin_unreachable) || __GNUC_PREREQ(4, 5)
259 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
260 #elif defined(_MSC_VER)
261 # define LLVM_BUILTIN_UNREACHABLE __assume(false)
264 /// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression
265 /// which causes the program to exit abnormally.
266 #if __has_builtin(__builtin_trap) || __GNUC_PREREQ(4, 3)
267 # define LLVM_BUILTIN_TRAP __builtin_trap()
269 # define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0
272 /// \macro LLVM_ASSUME_ALIGNED
273 /// \brief Returns a pointer with an assumed alignment.
274 #if __has_builtin(__builtin_assume_aligned) && __GNUC_PREREQ(4, 7)
275 # define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a)
276 #elif defined(LLVM_BUILTIN_UNREACHABLE)
277 // As of today, clang does not support __builtin_assume_aligned.
278 # define LLVM_ASSUME_ALIGNED(p, a) \
279 (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p)))
281 # define LLVM_ASSUME_ALIGNED(p, a) (p)
284 /// \macro LLVM_FUNCTION_NAME
285 /// \brief Expands to __func__ on compilers which support it. Otherwise,
286 /// expands to a compiler-dependent replacement.
287 #if defined(_MSC_VER)
288 # define LLVM_FUNCTION_NAME __FUNCTION__
290 # define LLVM_FUNCTION_NAME __func__
293 /// \macro LLVM_MEMORY_SANITIZER_BUILD
294 /// \brief Whether LLVM itself is built with MemorySanitizer instrumentation.
295 #if __has_feature(memory_sanitizer)
296 # define LLVM_MEMORY_SANITIZER_BUILD 1
297 # include <sanitizer/msan_interface.h>
299 # define LLVM_MEMORY_SANITIZER_BUILD 0
300 # define __msan_allocated_memory(p, size)
301 # define __msan_unpoison(p, size)
304 /// \macro LLVM_ADDRESS_SANITIZER_BUILD
305 /// \brief Whether LLVM itself is built with AddressSanitizer instrumentation.
306 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
307 # define LLVM_ADDRESS_SANITIZER_BUILD 1
309 # define LLVM_ADDRESS_SANITIZER_BUILD 0
312 /// \macro LLVM_IS_UNALIGNED_ACCESS_FAST
313 /// \brief Is unaligned memory access fast on the host machine.
315 /// Don't specialize on alignment for platforms where unaligned memory accesses
316 /// generates the same code as aligned memory accesses for common types.
317 #if defined(_M_AMD64) || defined(_M_IX86) || defined(__amd64) || \
318 defined(__amd64__) || defined(__x86_64) || defined(__x86_64__) || \
319 defined(_X86_) || defined(__i386) || defined(__i386__)
320 # define LLVM_IS_UNALIGNED_ACCESS_FAST 1
322 # define LLVM_IS_UNALIGNED_ACCESS_FAST 0
325 /// \macro LLVM_EXPLICIT
326 /// \brief Expands to explicit on compilers which support explicit conversion
327 /// operators. Otherwise expands to nothing.
328 #if __has_feature(cxx_explicit_conversions) || LLVM_MSC_PREREQ(1800)
329 #define LLVM_EXPLICIT explicit
331 #define LLVM_EXPLICIT
334 /// \brief Does the compiler support generalized initializers (using braced
335 /// lists and std::initializer_list). While clang may claim it supports general
336 /// initializers, if we're using MSVC's headers, we might not have a usable
337 /// std::initializer list type from the STL. Disable this for now.
338 #if __has_feature(cxx_generalized_initializers) && !defined(_MSC_VER)
339 #define LLVM_HAS_INITIALIZER_LISTS 1
341 #define LLVM_HAS_INITIALIZER_LISTS 0
344 /// \brief Mark debug helper function definitions like dump() that should not be
345 /// stripped from debug builds.
346 // FIXME: Move this to a private config.h as it's not usable in public headers.
347 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
348 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED
350 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE