2 * Copyright 2017 Facebook, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
22 #include <type_traits>
24 #include <folly/portability/Config.h>
26 #include <folly/CPortability.h>
28 // Unaligned loads and stores
30 #if FOLLY_HAVE_UNALIGNED_ACCESS
31 constexpr bool kHasUnalignedAccess = true;
33 constexpr bool kHasUnalignedAccess = false;
36 namespace portability_detail {
38 template <typename I, I A, I B>
39 using integral_max = std::integral_constant<I, (A < B) ? B : A>;
41 template <typename I, I A, I... Bs>
42 struct integral_sequence_max
43 : integral_max<I, A, integral_sequence_max<I, Bs...>::value> {};
45 template <typename I, I A>
46 struct integral_sequence_max<I, A> : std::integral_constant<I, A> {};
48 template <typename... Ts>
49 using max_alignment = integral_sequence_max<size_t, alignof(Ts)...>;
51 using max_basic_alignment = max_alignment<
68 constexpr size_t max_align_v = portability_detail::max_basic_alignment::value;
70 // max_align_t is a type which is aligned at least as strictly as the
71 // most-aligned basic type (see the specification of std::max_align_t). This
72 // implementation exists because 32-bit iOS platforms have a broken
73 // std::max_align_t (see below).
75 // You should refer to this as `::folly::max_align_t` in portable code, even if
76 // you have `using namespace folly;` because C11 defines a global namespace
77 // `max_align_t` type.
79 // To be certain, we consider every non-void fundamental type specified by the
80 // standard. On most platforms `long double` would be enough, but iOS 32-bit
81 // has an 8-byte aligned `double` and `long long int` and a 4-byte aligned
84 // So far we've covered locals and other non-allocated storage, but we also need
85 // confidence that allocated storage from `malloc`, `new`, etc will also be
86 // suitable for objects with this alignment reuirement.
88 // Apple document that their implementation of malloc will issue 16-byte
89 // granularity chunks for small allocations (large allocations are page-size
90 // granularity and page-aligned). We think that allocated storage will be
91 // suitable for these objects based on the following assumptions:
93 // 1. 16-byte granularity also means 16-byte aligned.
94 // 2. `new` and other allocators follow the `malloc` rules.
96 // We also have some anecdotal evidence: we don't see lots of misaligned-storage
97 // crashes on 32-bit iOS apps that use `double`.
99 // Apple's allocation reference: http://bit.ly/malloc-small
100 struct alignas(max_align_v) max_align_t {};
104 // compiler specific attribute translation
105 // msvc should come first, so if clang is in msvc mode it gets the right defines
107 #if defined(__clang__) || defined(__GNUC__)
108 # define FOLLY_ALIGNED(size) __attribute__((__aligned__(size)))
109 #elif defined(_MSC_VER)
110 # define FOLLY_ALIGNED(size) __declspec(align(size))
112 # error Cannot define FOLLY_ALIGNED on this platform
114 #define FOLLY_ALIGNED_MAX FOLLY_ALIGNED(::folly::max_align_v)
116 // NOTE: this will only do checking in msvc with versions that support /analyze
118 # ifdef _USE_ATTRIBUTES_FOR_SAL
119 # undef _USE_ATTRIBUTES_FOR_SAL
122 # define _USE_ATTRIBUTES_FOR_SAL 1
123 # include <sal.h> // @manual
124 # define FOLLY_PRINTF_FORMAT _Printf_format_string_
125 # define FOLLY_PRINTF_FORMAT_ATTR(format_param, dots_param) /**/
127 # define FOLLY_PRINTF_FORMAT /**/
128 # define FOLLY_PRINTF_FORMAT_ATTR(format_param, dots_param) \
129 __attribute__((__format__(__printf__, format_param, dots_param)))
133 #if defined(__clang__) || defined(__GNUC__)
134 # define FOLLY_DEPRECATED(msg) __attribute__((__deprecated__(msg)))
135 #elif defined(_MSC_VER)
136 # define FOLLY_DEPRECATED(msg) __declspec(deprecated(msg))
138 # define FOLLY_DEPRECATED(msg)
141 // warn unused result
142 #if defined(__has_cpp_attribute)
143 #if __has_cpp_attribute(nodiscard)
144 #define FOLLY_NODISCARD [[nodiscard]]
147 #if !defined FOLLY_NODISCARD
148 #if defined(_MSC_VER) && (_MSC_VER >= 1700)
149 #define FOLLY_NODISCARD _Check_return_
150 #elif defined(__clang__) || defined(__GNUC__)
151 #define FOLLY_NODISCARD __attribute__((__warn_unused_result__))
153 #define FOLLY_NODISCARD
159 # define FOLLY_TARGET_ATTRIBUTE(target)
161 # define FOLLY_TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))
164 // detection for 64 bit
165 #if defined(__x86_64__) || defined(_M_X64)
171 #if defined(__aarch64__)
172 # define FOLLY_AARCH64 1
174 # define FOLLY_AARCH64 0
177 #if defined (__powerpc64__)
178 # define FOLLY_PPC64 1
180 # define FOLLY_PPC64 0
184 constexpr bool kIsArchAmd64 = FOLLY_X64 == 1;
185 constexpr bool kIsArchAArch64 = FOLLY_AARCH64 == 1;
186 constexpr bool kIsArchPPC64 = FOLLY_PPC64 == 1;
191 #if FOLLY_SANITIZE_ADDRESS
192 constexpr bool kIsSanitizeAddress = true;
194 constexpr bool kIsSanitizeAddress = false;
197 #if FOLLY_SANITIZE_THREAD
198 constexpr bool kIsSanitizeThread = true;
200 constexpr bool kIsSanitizeThread = false;
204 // packing is very ugly in msvc
206 # define FOLLY_PACK_ATTR /**/
207 # define FOLLY_PACK_PUSH __pragma(pack(push, 1))
208 # define FOLLY_PACK_POP __pragma(pack(pop))
209 #elif defined(__clang__) || defined(__GNUC__)
210 # define FOLLY_PACK_ATTR __attribute__((__packed__))
211 # define FOLLY_PACK_PUSH /**/
212 # define FOLLY_PACK_POP /**/
214 # define FOLLY_PACK_ATTR /**/
215 # define FOLLY_PACK_PUSH /**/
216 # define FOLLY_PACK_POP /**/
219 // Generalize warning push/pop.
220 #if defined(_MSC_VER)
221 # define FOLLY_PUSH_WARNING __pragma(warning(push))
222 # define FOLLY_POP_WARNING __pragma(warning(pop))
223 // Disable the GCC warnings.
224 # define FOLLY_GCC_DISABLE_WARNING(warningName)
225 # define FOLLY_MSVC_DISABLE_WARNING(warningNumber) __pragma(warning(disable: warningNumber))
226 #elif defined(__clang__) || defined(__GNUC__)
227 # define FOLLY_PUSH_WARNING _Pragma("GCC diagnostic push")
228 # define FOLLY_POP_WARNING _Pragma("GCC diagnostic pop")
229 # define FOLLY_GCC_DISABLE_WARNING_INTERNAL2(warningName) #warningName
230 # define FOLLY_GCC_DISABLE_WARNING(warningName) \
232 FOLLY_GCC_DISABLE_WARNING_INTERNAL2(GCC diagnostic ignored warningName))
233 // Disable the MSVC warnings.
234 # define FOLLY_MSVC_DISABLE_WARNING(warningNumber)
236 # define FOLLY_PUSH_WARNING
237 # define FOLLY_POP_WARNING
238 # define FOLLY_GCC_DISABLE_WARNING(warningName)
239 # define FOLLY_MSVC_DISABLE_WARNING(warningNumber)
242 #ifdef FOLLY_HAVE_SHADOW_LOCAL_WARNINGS
243 #define FOLLY_GCC_DISABLE_NEW_SHADOW_WARNINGS \
244 FOLLY_GCC_DISABLE_WARNING("-Wshadow-compatible-local") \
245 FOLLY_GCC_DISABLE_WARNING("-Wshadow-local")
247 #define FOLLY_GCC_DISABLE_NEW_SHADOW_WARNINGS /* empty */
250 /* Platform specific TLS support
251 * gcc implements __thread
252 * msvc implements __declspec(thread)
253 * the semantics are the same
254 * (but remember __thread has different semantics when using emutls (ex. apple))
256 #if defined(_MSC_VER)
257 # define FOLLY_TLS __declspec(thread)
258 #elif defined(__GNUC__) || defined(__clang__)
259 # define FOLLY_TLS __thread
261 # error cannot define platform specific thread local storage
268 // It turns out that GNU libstdc++ and LLVM libc++ differ on how they implement
269 // the 'std' namespace; the latter uses inline namespaces. Wrap this decision
270 // up in a macro to make forward-declarations easier.
272 #include <__config> // @manual
273 #define FOLLY_NAMESPACE_STD_BEGIN _LIBCPP_BEGIN_NAMESPACE_STD
274 #define FOLLY_NAMESPACE_STD_END _LIBCPP_END_NAMESPACE_STD
276 #define FOLLY_NAMESPACE_STD_BEGIN namespace std {
277 #define FOLLY_NAMESPACE_STD_END }
280 // If the new c++ ABI is used, __cxx11 inline namespace needs to be added to
281 // some types, e.g. std::list.
282 #if _GLIBCXX_USE_CXX11_ABI
283 #define FOLLY_GLIBCXX_NAMESPACE_CXX11_BEGIN \
284 inline _GLIBCXX_BEGIN_NAMESPACE_CXX11
285 # define FOLLY_GLIBCXX_NAMESPACE_CXX11_END _GLIBCXX_END_NAMESPACE_CXX11
287 # define FOLLY_GLIBCXX_NAMESPACE_CXX11_BEGIN
288 # define FOLLY_GLIBCXX_NAMESPACE_CXX11_END
291 // MSVC specific defines
292 // mainly for posix compat
294 #include <folly/portability/SysTypes.h>
296 // compiler specific to compiler specific
298 # define __PRETTY_FUNCTION__ __FUNCSIG__
300 // Hide a GCC specific thing that breaks MSVC if left alone.
301 # define __extension__
303 // We have compiler support for the newest of the new, but
304 // MSVC doesn't tell us that.
312 constexpr auto kIsDebug = false;
314 constexpr auto kIsDebug = true;
321 // It's MSVC, so we just have to guess ... and allow an override
322 #ifdef FOLLY_ENDIAN_BE
323 constexpr auto kIsLittleEndian = false;
325 constexpr auto kIsLittleEndian = true;
328 constexpr auto kIsLittleEndian = __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__;
330 constexpr auto kIsBigEndian = !kIsLittleEndian;
334 # if defined(__SSE4_2__)
336 # define FOLLY_SSE_MINOR 2
337 # elif defined(__SSE4_1__)
339 # define FOLLY_SSE_MINOR 1
340 # elif defined(__SSE4__)
342 # define FOLLY_SSE_MINOR 0
343 # elif defined(__SSE3__)
345 # define FOLLY_SSE_MINOR 0
346 # elif defined(__SSE2__)
348 # define FOLLY_SSE_MINOR 0
349 # elif defined(__SSE__)
351 # define FOLLY_SSE_MINOR 0
354 # define FOLLY_SSE_MINOR 0
358 #define FOLLY_SSE_PREREQ(major, minor) \
359 (FOLLY_SSE > major || FOLLY_SSE == major && FOLLY_SSE_MINOR >= minor)
361 #if FOLLY_UNUSUAL_GFLAGS_NAMESPACE
362 namespace FOLLY_GFLAGS_NAMESPACE { }
364 using namespace FOLLY_GFLAGS_NAMESPACE;
365 } // namespace gflags
368 // for TARGET_OS_IPHONE
370 #include <TargetConditionals.h> // @manual
373 // RTTI may not be enabled for this compilation unit.
374 #if defined(__GXX_RTTI) || defined(__cpp_rtti) || \
375 (defined(_MSC_VER) && defined(_CPPRTTI))
376 # define FOLLY_HAS_RTTI 1
379 #if defined(__APPLE__) || defined(_MSC_VER)
380 #define FOLLY_STATIC_CTOR_PRIORITY_MAX
382 // 101 is the highest priority allowed by the init_priority attribute.
383 // This priority is already used by JEMalloc and other memory allocators so
384 // we will take the next one.
385 #define FOLLY_STATIC_CTOR_PRIORITY_MAX __attribute__((__init_priority__(102)))
391 constexpr auto kIsObjC = true;
393 constexpr auto kIsObjC = false;
396 #if defined(__linux__) && !FOLLY_MOBILE
397 constexpr auto kIsLinux = true;
399 constexpr auto kIsLinux = false;
403 constexpr auto kIsWindows = true;
404 constexpr auto kMscVer = _MSC_VER;
406 constexpr auto kIsWindows = false;
407 constexpr auto kMscVer = 0;
411 // Define FOLLY_USE_CPP14_CONSTEXPR to be true if the compiler's C++14
412 // constexpr support is "good enough".
413 #ifndef FOLLY_USE_CPP14_CONSTEXPR
414 #if defined(__clang__)
415 #define FOLLY_USE_CPP14_CONSTEXPR __cplusplus >= 201300L
416 #elif defined(__GNUC__)
417 #define FOLLY_USE_CPP14_CONSTEXPR __cplusplus >= 201304L
419 #define FOLLY_USE_CPP14_CONSTEXPR 0 // MSVC?
423 #if FOLLY_USE_CPP14_CONSTEXPR
424 #define FOLLY_CPP14_CONSTEXPR constexpr
426 #define FOLLY_CPP14_CONSTEXPR inline
429 #if __cpp_coroutines >= 201703L || (_MSC_VER && _RESUMABLE_FUNCTIONS_SUPPORTED)
430 #define FOLLY_HAS_COROUTINES 1