2 * Copyright 2014 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.
17 #ifndef FOLLY_PORTABILITY_H_
18 #define FOLLY_PORTABILITY_H_
20 #ifndef FOLLY_NO_CONFIG
21 #include "folly-config.h"
24 #if FOLLY_HAVE_FEATURES_H
28 #include "CPortability.h"
30 #if FOLLY_HAVE_SCHED_H
32 #ifndef FOLLY_HAVE_PTHREAD_YIELD
33 #define pthread_yield sched_yield
38 // MaxAlign: max_align_t isn't supported by gcc
40 struct MaxAlign { char c; } __attribute__((aligned));
42 # error Cannot define MaxAlign on this platform
45 // compiler specific attribute translation
46 // msvc should come first, so if clang is in msvc mode it gets the right defines
50 # define FOLLY_NORETURN __declspec(noreturn)
51 #elif defined(__clang__) || defined(__GNUC__)
52 # define FOLLY_NORETURN __attribute__((noreturn))
54 # define FOLLY_NORETURN
59 # define FOLLY_NOINLINE __declspec(noinline)
60 #elif defined(__clang__) || defined(__GNUC__)
61 # define FOLLY_NOINLINE __attribute__((noinline))
63 # define FOLLY_NOINLINE
68 # define FOLLY_ALWAYS_INLINE __forceinline
69 #elif defined(__clang__) || defined(__GNUC__)
70 # define FOLLY_ALWAYS_INLINE inline __attribute__((always_inline))
72 # define FOLLY_ALWAYS_INLINE
75 // detection for 64 bit
76 #if defined(__x86_64__) || defined(_M_X64)
82 // packing is very ugly in msvc
84 # define FOLLY_PACK_ATTR /**/
85 # define FOLLY_PACK_PUSH __pragma(pack(push, 1))
86 # define FOLLY_PACK_POP __pragma(pack(pop))
87 #elif defined(__clang__) || defined(__GNUC__)
88 # define FOLLY_PACK_ATTR __attribute__((packed))
89 # define FOLLY_PACK_PUSH /**/
90 # define FOLLY_PACK_POP /**/
92 # define FOLLY_PACK_ATTR /**/
93 # define FOLLY_PACK_PUSH /**/
94 # define FOLLY_PACK_POP /**/
97 // portable version check
99 # if defined __GNUC__ && defined __GNUC_MINOR__
100 # define __GNUC_PREREQ(maj, min) ((__GNUC__ << 16) + __GNUC_MINOR__ >= \
101 ((maj) << 16) + (min))
103 # define __GNUC_PREREQ(maj, min) 0
108 /* Define macro wrappers for C++11's "final" and "override" keywords, which
109 * are supported in gcc 4.7 but not gcc 4.6. */
110 #if !defined(FOLLY_FINAL) && !defined(FOLLY_OVERRIDE)
111 # if defined(__clang__) || __GNUC_PREREQ(4, 7)
112 # define FOLLY_FINAL final
113 # define FOLLY_OVERRIDE override
115 # define FOLLY_FINAL /**/
116 # define FOLLY_OVERRIDE /**/
120 /* Platform specific TLS support
121 * gcc implements __thread
122 * msvc implements __declspec(thread)
123 * the semantics are the same (but remember __thread is broken on apple)
125 #if defined(_MSC_VER)
126 # define FOLLY_TLS __declspec(thread)
127 #elif defined(__GNUC__) || defined(__clang__)
128 # define FOLLY_TLS __thread
130 # error cannot define platform specific thread local storage
133 // Define to 1 if you have the `preadv' and `pwritev' functions, respectively
134 #if !defined(FOLLY_HAVE_PREADV) && !defined(FOLLY_HAVE_PWRITEV)
135 # if defined(__GLIBC_PREREQ)
136 # if __GLIBC_PREREQ(2, 10)
137 # define FOLLY_HAVE_PREADV 1
138 # define FOLLY_HAVE_PWRITEV 1
143 // It turns out that GNU libstdc++ and LLVM libc++ differ on how they implement
144 // the 'std' namespace; the latter uses inline namepsaces. Wrap this decision
145 // up in a macro to make forward-declarations easier.
147 #define FOLLY_NAMESPACE_STD_BEGIN _LIBCPP_BEGIN_NAMESPACE_STD
148 #define FOLLY_NAMESPACE_STD_END _LIBCPP_END_NAMESPACE_STD
150 #define FOLLY_NAMESPACE_STD_BEGIN namespace std {
151 #define FOLLY_NAMESPACE_STD_END }
154 // Some platforms lack clock_gettime(2) and clock_getres(2). Inject our own
155 // versions of these into the global namespace.
156 #if FOLLY_HAVE_CLOCK_GETTIME
159 #include "folly/detail/Clock.h"
162 // Provide our own std::__throw_* wrappers for platforms that don't have them
163 #if FOLLY_HAVE_BITS_FUNCTEXCEPT_H
164 #include <bits/functexcept.h>
166 #include "folly/detail/FunctionalExcept.h"
169 #if defined(__cplusplus)
170 // Unfortunately, boost::has_trivial_copy<T> is broken in libc++ due to its
171 // usage of __has_trivial_copy(), so we can't use it as a
172 // least-common-denominator for C++11 implementations that don't support
173 // std::is_trivially_copyable<T>.
175 // http://stackoverflow.com/questions/12754886/has-trivial-copy-behaves-differently-in-clang-and-gcc-whos-right
177 // As a result, use std::is_trivially_copyable() where it exists, and fall back
178 // to Boost otherwise.
179 #if FOLLY_HAVE_STD__IS_TRIVIALLY_COPYABLE
180 #include <type_traits>
181 #define FOLLY_IS_TRIVIALLY_COPYABLE(T) \
182 (std::is_trivially_copyable<T>::value)
184 #include <boost/type_traits.hpp>
185 #define FOLLY_IS_TRIVIALLY_COPYABLE(T) \
186 (boost::has_trivial_copy<T>::value && \
187 boost::has_trivial_destructor<T>::value)
189 #endif // __cplusplus
191 #endif // FOLLY_PORTABILITY_H_