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 /// * 1600: Microsoft Visual Studio 2010 / 10.0
51 /// * 1700: Microsoft Visual Studio 2012 / 11.0
52 /// * 1800: Microsoft Visual Studio 2013 / 12.0
54 #define LLVM_MSC_PREREQ(version) (_MSC_VER >= (version))
56 #define LLVM_MSC_PREREQ(version) 0
59 /// \brief Does the compiler support r-value reference *this?
61 /// Sadly, this is separate from just r-value reference support because GCC
62 /// implemented everything but this thus far. No release of GCC yet has support
63 /// for this feature so it is enabled with Clang only.
64 /// FIXME: This should change to a version check when GCC grows support for it.
65 #if __has_feature(cxx_rvalue_references)
66 #define LLVM_HAS_RVALUE_REFERENCE_THIS 1
68 #define LLVM_HAS_RVALUE_REFERENCE_THIS 0
71 /// \macro LLVM_HAS_CXX11_TYPETRAITS
72 /// \brief Does the compiler have the C++11 type traits.
74 /// #include <type_traits>
77 /// * {true,false}_type
78 /// * is_constructible
80 #define LLVM_HAS_CXX11_TYPETRAITS 1
82 /// \macro LLVM_HAS_CXX11_STDLIB
83 /// \brief Does the compiler have the C++11 standard library.
85 /// Implies LLVM_HAS_RVALUE_REFERENCES, LLVM_HAS_CXX11_TYPETRAITS
86 #define LLVM_HAS_CXX11_STDLIB 1
88 /// \macro LLVM_HAS_VARIADIC_TEMPLATES
89 /// \brief Does this compiler support variadic templates.
91 /// Implies LLVM_HAS_RVALUE_REFERENCES and the existence of std::forward.
92 #if __has_feature(cxx_variadic_templates) || LLVM_MSC_PREREQ(1800)
93 # define LLVM_HAS_VARIADIC_TEMPLATES 1
95 # define LLVM_HAS_VARIADIC_TEMPLATES 0
98 /// llvm_move - Expands to ::std::move. This is a hold-over from when we did
99 /// not support R-value references.
100 #define llvm_move(value) (::std::move(value))
102 /// Expands to '&' if r-value references are supported.
104 /// This can be used to provide l-value/r-value overrides of member functions.
105 /// The r-value override should be guarded by LLVM_HAS_RVALUE_REFERENCE_THIS
106 #if LLVM_HAS_RVALUE_REFERENCE_THIS
107 #define LLVM_LVALUE_FUNCTION &
109 #define LLVM_LVALUE_FUNCTION
112 /// LLVM_DELETED_FUNCTION - Expands to = delete if the compiler supports it.
113 /// Use to mark functions as uncallable. Member functions with this should
114 /// be declared private so that some behavior is kept in C++03 mode.
118 /// DontCopy(const DontCopy&) LLVM_DELETED_FUNCTION;
119 /// DontCopy &operator =(const DontCopy&) LLVM_DELETED_FUNCTION;
123 #if __has_feature(cxx_deleted_functions) || \
124 defined(__GXX_EXPERIMENTAL_CXX0X__) || LLVM_MSC_PREREQ(1800)
125 #define LLVM_DELETED_FUNCTION = delete
127 #define LLVM_DELETED_FUNCTION
130 /// LLVM_FINAL - Expands to 'final' if the compiler supports it.
131 /// Use to mark classes or virtual methods as final.
132 #if __has_feature(cxx_override_control) || \
133 (defined(__GXX_EXPERIMENTAL_CXX0X__) && __GNUC_PREREQ(4, 7)) || \
134 LLVM_MSC_PREREQ(1700)
135 #define LLVM_FINAL final
140 /// LLVM_OVERRIDE - Expands to 'override' if the compiler supports it.
141 /// Use to mark virtual methods as overriding a base class method.
142 #if __has_feature(cxx_override_control) || \
143 (defined(__GXX_EXPERIMENTAL_CXX0X__) && __GNUC_PREREQ(4, 7)) || \
144 LLVM_MSC_PREREQ(1700)
145 #define LLVM_OVERRIDE override
147 #define LLVM_OVERRIDE
150 #if __has_feature(cxx_constexpr) || defined(__GXX_EXPERIMENTAL_CXX0X__)
151 # define LLVM_CONSTEXPR constexpr
153 # define LLVM_CONSTEXPR
156 /// LLVM_LIBRARY_VISIBILITY - If a class marked with this attribute is linked
157 /// into a shared library, then the class should be private to the library and
158 /// not accessible from outside it. Can also be used to mark variables and
159 /// functions, making them private to any shared library they are linked into.
160 /// On PE/COFF targets, library visibility is the default, so this isn't needed.
161 #if (__has_attribute(visibility) || __GNUC_PREREQ(4, 0)) && \
162 !defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32)
163 #define LLVM_LIBRARY_VISIBILITY __attribute__ ((visibility("hidden")))
165 #define LLVM_LIBRARY_VISIBILITY
168 #if __has_attribute(used) || __GNUC_PREREQ(3, 1)
169 #define LLVM_ATTRIBUTE_USED __attribute__((__used__))
171 #define LLVM_ATTRIBUTE_USED
174 #if __has_attribute(warn_unused_result) || __GNUC_PREREQ(3, 4)
175 #define LLVM_ATTRIBUTE_UNUSED_RESULT __attribute__((__warn_unused_result__))
177 #define LLVM_ATTRIBUTE_UNUSED_RESULT
180 // Some compilers warn about unused functions. When a function is sometimes
181 // used or not depending on build settings (e.g. a function only called from
182 // within "assert"), this attribute can be used to suppress such warnings.
184 // However, it shouldn't be used for unused *variables*, as those have a much
185 // more portable solution:
186 // (void)unused_var_name;
187 // Prefer cast-to-void wherever it is sufficient.
188 #if __has_attribute(unused) || __GNUC_PREREQ(3, 1)
189 #define LLVM_ATTRIBUTE_UNUSED __attribute__((__unused__))
191 #define LLVM_ATTRIBUTE_UNUSED
194 // FIXME: Provide this for PE/COFF targets.
195 #if (__has_attribute(weak) || __GNUC_PREREQ(4, 0)) && \
196 (!defined(__MINGW32__) && !defined(__CYGWIN__) && !defined(LLVM_ON_WIN32))
197 #define LLVM_ATTRIBUTE_WEAK __attribute__((__weak__))
199 #define LLVM_ATTRIBUTE_WEAK
202 // Prior to clang 3.2, clang did not accept any spelling of
203 // __has_attribute(const), so assume it is supported.
204 #if defined(__clang__) || defined(__GNUC__)
205 // aka 'CONST' but following LLVM Conventions.
206 #define LLVM_READNONE __attribute__((__const__))
208 #define LLVM_READNONE
211 #if __has_attribute(pure) || defined(__GNUC__)
212 // aka 'PURE' but following LLVM Conventions.
213 #define LLVM_READONLY __attribute__((__pure__))
215 #define LLVM_READONLY
218 #if __has_builtin(__builtin_expect) || __GNUC_PREREQ(4, 0)
219 #define LLVM_LIKELY(EXPR) __builtin_expect((bool)(EXPR), true)
220 #define LLVM_UNLIKELY(EXPR) __builtin_expect((bool)(EXPR), false)
222 #define LLVM_LIKELY(EXPR) (EXPR)
223 #define LLVM_UNLIKELY(EXPR) (EXPR)
226 // C++ doesn't support 'extern template' of template specializations. GCC does,
227 // but requires __extension__ before it. In the header, use this:
228 // EXTERN_TEMPLATE_INSTANTIATION(class foo<bar>);
229 // in the .cpp file, use this:
230 // TEMPLATE_INSTANTIATION(class foo<bar>);
232 #define EXTERN_TEMPLATE_INSTANTIATION(X) __extension__ extern template X
233 #define TEMPLATE_INSTANTIATION(X) template X
235 #define EXTERN_TEMPLATE_INSTANTIATION(X)
236 #define TEMPLATE_INSTANTIATION(X)
239 /// LLVM_ATTRIBUTE_NOINLINE - On compilers where we have a directive to do so,
240 /// mark a method "not for inlining".
241 #if __has_attribute(noinline) || __GNUC_PREREQ(3, 4)
242 #define LLVM_ATTRIBUTE_NOINLINE __attribute__((noinline))
243 #elif defined(_MSC_VER)
244 #define LLVM_ATTRIBUTE_NOINLINE __declspec(noinline)
246 #define LLVM_ATTRIBUTE_NOINLINE
249 /// LLVM_ATTRIBUTE_ALWAYS_INLINE - On compilers where we have a directive to do
250 /// so, mark a method "always inline" because it is performance sensitive. GCC
251 /// 3.4 supported this but is buggy in various cases and produces unimplemented
252 /// errors, just use it in GCC 4.0 and later.
253 #if __has_attribute(always_inline) || __GNUC_PREREQ(4, 0)
254 #define LLVM_ATTRIBUTE_ALWAYS_INLINE inline __attribute__((always_inline))
255 #elif defined(_MSC_VER)
256 #define LLVM_ATTRIBUTE_ALWAYS_INLINE __forceinline
258 #define LLVM_ATTRIBUTE_ALWAYS_INLINE
262 #define LLVM_ATTRIBUTE_NORETURN __attribute__((noreturn))
263 #elif defined(_MSC_VER)
264 #define LLVM_ATTRIBUTE_NORETURN __declspec(noreturn)
266 #define LLVM_ATTRIBUTE_NORETURN
269 /// LLVM_EXTENSION - Support compilers where we have a keyword to suppress
270 /// pedantic diagnostics.
272 #define LLVM_EXTENSION __extension__
274 #define LLVM_EXTENSION
277 // LLVM_ATTRIBUTE_DEPRECATED(decl, "message")
278 #if __has_feature(attribute_deprecated_with_message)
279 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
280 decl __attribute__((deprecated(message)))
281 #elif defined(__GNUC__)
282 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
283 decl __attribute__((deprecated))
284 #elif defined(_MSC_VER)
285 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
286 __declspec(deprecated(message)) decl
288 # define LLVM_ATTRIBUTE_DEPRECATED(decl, message) \
292 /// LLVM_BUILTIN_UNREACHABLE - On compilers which support it, expands
293 /// to an expression which states that it is undefined behavior for the
294 /// compiler to reach this point. Otherwise is not defined.
295 #if __has_builtin(__builtin_unreachable) || __GNUC_PREREQ(4, 5)
296 # define LLVM_BUILTIN_UNREACHABLE __builtin_unreachable()
297 #elif defined(_MSC_VER)
298 # define LLVM_BUILTIN_UNREACHABLE __assume(false)
301 /// LLVM_BUILTIN_TRAP - On compilers which support it, expands to an expression
302 /// which causes the program to exit abnormally.
303 #if __has_builtin(__builtin_trap) || __GNUC_PREREQ(4, 3)
304 # define LLVM_BUILTIN_TRAP __builtin_trap()
306 # define LLVM_BUILTIN_TRAP *(volatile int*)0x11 = 0
309 /// \macro LLVM_ASSUME_ALIGNED
310 /// \brief Returns a pointer with an assumed alignment.
311 #if __has_builtin(__builtin_assume_aligned) && __GNUC_PREREQ(4, 7)
312 # define LLVM_ASSUME_ALIGNED(p, a) __builtin_assume_aligned(p, a)
313 #elif defined(LLVM_BUILTIN_UNREACHABLE)
314 // As of today, clang does not support __builtin_assume_aligned.
315 # define LLVM_ASSUME_ALIGNED(p, a) \
316 (((uintptr_t(p) % (a)) == 0) ? (p) : (LLVM_BUILTIN_UNREACHABLE, (p)))
318 # define LLVM_ASSUME_ALIGNED(p, a) (p)
321 /// \macro LLVM_FUNCTION_NAME
322 /// \brief Expands to __func__ on compilers which support it. Otherwise,
323 /// expands to a compiler-dependent replacement.
324 #if defined(_MSC_VER)
325 # define LLVM_FUNCTION_NAME __FUNCTION__
327 # define LLVM_FUNCTION_NAME __func__
330 /// \macro LLVM_MEMORY_SANITIZER_BUILD
331 /// \brief Whether LLVM itself is built with MemorySanitizer instrumentation.
332 #if __has_feature(memory_sanitizer)
333 # define LLVM_MEMORY_SANITIZER_BUILD 1
334 # include <sanitizer/msan_interface.h>
336 # define LLVM_MEMORY_SANITIZER_BUILD 0
337 # define __msan_allocated_memory(p, size)
338 # define __msan_unpoison(p, size)
341 /// \macro LLVM_ADDRESS_SANITIZER_BUILD
342 /// \brief Whether LLVM itself is built with AddressSanitizer instrumentation.
343 #if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
344 # define LLVM_ADDRESS_SANITIZER_BUILD 1
346 # define LLVM_ADDRESS_SANITIZER_BUILD 0
349 /// \macro LLVM_IS_UNALIGNED_ACCESS_FAST
350 /// \brief Is unaligned memory access fast on the host machine.
352 /// Don't specialize on alignment for platforms where unaligned memory accesses
353 /// generates the same code as aligned memory accesses for common types.
354 #if defined(_M_AMD64) || defined(_M_IX86) || defined(__amd64) || \
355 defined(__amd64__) || defined(__x86_64) || defined(__x86_64__) || \
356 defined(_X86_) || defined(__i386) || defined(__i386__)
357 # define LLVM_IS_UNALIGNED_ACCESS_FAST 1
359 # define LLVM_IS_UNALIGNED_ACCESS_FAST 0
362 /// \macro LLVM_EXPLICIT
363 /// \brief Expands to explicit on compilers which support explicit conversion
364 /// operators. Otherwise expands to nothing.
365 #if __has_feature(cxx_explicit_conversions) || \
366 defined(__GXX_EXPERIMENTAL_CXX0X__) || LLVM_MSC_PREREQ(1800)
367 #define LLVM_EXPLICIT explicit
369 #define LLVM_EXPLICIT
372 /// \macro LLVM_STATIC_ASSERT
373 /// \brief Expands to C/C++'s static_assert on compilers which support it.
374 #if __has_feature(cxx_static_assert) || \
375 defined(__GXX_EXPERIMENTAL_CXX0X__) || LLVM_MSC_PREREQ(1600)
376 # define LLVM_STATIC_ASSERT(expr, msg) static_assert(expr, msg)
377 #elif __has_feature(c_static_assert)
378 # define LLVM_STATIC_ASSERT(expr, msg) _Static_assert(expr, msg)
379 #elif __has_extension(c_static_assert)
380 # define LLVM_STATIC_ASSERT(expr, msg) LLVM_EXTENSION _Static_assert(expr, msg)
382 # define LLVM_STATIC_ASSERT(expr, msg)
385 /// \macro LLVM_ENUM_INT_TYPE
386 /// \brief Expands to colon followed by the given integral type on compilers
387 /// which support C++11 strong enums. This can be used to make enums unsigned
389 #if __has_feature(cxx_strong_enums) || LLVM_MSC_PREREQ(1600)
390 # define LLVM_ENUM_INT_TYPE(intty) : intty
392 # define LLVM_ENUM_INT_TYPE(intty)
395 /// \brief Does the compiler support C++11 semantics for strongly typed forward
397 #if __has_feature(cxx_strong_enums) || LLVM_MSC_PREREQ(1700)
398 #define LLVM_HAS_STRONG_ENUMS 1
400 #define LLVM_HAS_STRONG_ENUMS 0
403 /// \brief Does the compiler support generalized initializers (using braced
404 /// lists and std::initializer_list). While clang may claim it supports general
405 /// initializers, if we're using MSVC's headers, we might not have a usable
406 /// std::initializer list type from the STL. Disable this for now.
407 #if __has_feature(cxx_generalized_initializers) && !defined(_MSC_VER)
408 #define LLVM_HAS_INITIALIZER_LISTS 1
410 #define LLVM_HAS_INITIALIZER_LISTS 0
413 /// \brief Mark debug helper function definitions like dump() that should not be
414 /// stripped from debug builds.
415 // FIXME: Move this to a private config.h as it's not usable in public headers.
416 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
417 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE LLVM_ATTRIBUTE_USED
419 #define LLVM_DUMP_METHOD LLVM_ATTRIBUTE_NOINLINE