Portability.h

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/*
 * Copyright 2011-present Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <cstddef>

#include <folly/CPortability.h>
#include <folly/portability/Config.h>

// Unaligned loads and stores
namespace folly {
#if FOLLY_HAVE_UNALIGNED_ACCESS
constexpr bool kHasUnalignedAccess = true;
#else
constexpr bool kHasUnalignedAccess = false;
#endif
} // namespace folly

// compiler specific attribute translation
// msvc should come first, so if clang is in msvc mode it gets the right defines

// NOTE: this will only do checking in msvc with versions that support /analyze
#if _MSC_VER
#ifdef _USE_ATTRIBUTES_FOR_SAL
#undef _USE_ATTRIBUTES_FOR_SAL
#endif
/* nolint */
#define _USE_ATTRIBUTES_FOR_SAL 1
#include <sal.h> // @manual
#define FOLLY_PRINTF_FORMAT _Printf_format_string_
#define FOLLY_PRINTF_FORMAT_ATTR(format_param, dots_param) 
#else
#define FOLLY_PRINTF_FORMAT 
#define FOLLY_PRINTF_FORMAT_ATTR(format_param, dots_param) \
  __attribute__((__format__(__printf__, format_param, dots_param)))
#endif

// warn unused result
#if defined(__has_cpp_attribute)
#if __has_cpp_attribute(nodiscard)
#define FOLLY_NODISCARD [[nodiscard]]
#endif
#endif
#if !defined FOLLY_NODISCARD
#if defined(_MSC_VER) && (_MSC_VER >= 1700)
#define FOLLY_NODISCARD _Check_return_
#elif defined(__clang__) || defined(__GNUC__)
#define FOLLY_NODISCARD __attribute__((__warn_unused_result__))
#else
#define FOLLY_NODISCARD
#endif
#endif

// target
#ifdef _MSC_VER
#define FOLLY_TARGET_ATTRIBUTE(target)
#else
#define FOLLY_TARGET_ATTRIBUTE(target) __attribute__((__target__(target)))
#endif

// detection for 64 bit
#if defined(__x86_64__) || defined(_M_X64)
#define FOLLY_X64 1
#else
#define FOLLY_X64 0
#endif

#if defined(__arm__)
#define FOLLY_ARM 1
#else
#define FOLLY_ARM 0
#endif

#if defined(__aarch64__)
#define FOLLY_AARCH64 1
#else
#define FOLLY_AARCH64 0
#endif

#if defined(__powerpc64__)
#define FOLLY_PPC64 1
#else
#define FOLLY_PPC64 0
#endif

namespace folly {
constexpr bool kIsArchArm = FOLLY_ARM == 1;
constexpr bool kIsArchAmd64 = FOLLY_X64 == 1;
constexpr bool kIsArchAArch64 = FOLLY_AARCH64 == 1;
constexpr bool kIsArchPPC64 = FOLLY_PPC64 == 1;
} // namespace folly

namespace folly {

#if FOLLY_ASAN_ENABLED
constexpr bool kIsSanitizeAddress = true;
#else
constexpr bool kIsSanitizeAddress = false;
#endif

#if FOLLY_SANITIZE_THREAD
constexpr bool kIsSanitizeThread = true;
#else
constexpr bool kIsSanitizeThread = false;
#endif

#if FOLLY_SANITIZE
constexpr bool kIsSanitize = true;
#else
constexpr bool kIsSanitize = false;
#endif
} // namespace folly

// packing is very ugly in msvc
#ifdef _MSC_VER
#define FOLLY_PACK_ATTR 
#define FOLLY_PACK_PUSH __pragma(pack(push, 1))
#define FOLLY_PACK_POP __pragma(pack(pop))
#elif defined(__clang__) || defined(__GNUC__)
#define FOLLY_PACK_ATTR __attribute__((__packed__))
#define FOLLY_PACK_PUSH 
#define FOLLY_PACK_POP 
#else
#define FOLLY_PACK_ATTR 
#define FOLLY_PACK_PUSH 
#define FOLLY_PACK_POP 
#endif

// Generalize warning push/pop.
#if defined(_MSC_VER)
#define FOLLY_PUSH_WARNING __pragma(warning(push))
#define FOLLY_POP_WARNING __pragma(warning(pop))
// Disable the GCC warnings.
#define FOLLY_GNU_DISABLE_WARNING(warningName)
#define FOLLY_GCC_DISABLE_WARNING(warningName)
#define FOLLY_CLANG_DISABLE_WARNING(warningName)
#define FOLLY_MSVC_DISABLE_WARNING(warningNumber) \
  __pragma(warning(disable : warningNumber))
#elif defined(__GNUC__)
// Clang & GCC
#define FOLLY_PUSH_WARNING _Pragma("GCC diagnostic push")
#define FOLLY_POP_WARNING _Pragma("GCC diagnostic pop")
#define FOLLY_GNU_DISABLE_WARNING_INTERNAL2(warningName) #warningName
#define FOLLY_GNU_DISABLE_WARNING(warningName) \
  _Pragma(                                     \
      FOLLY_GNU_DISABLE_WARNING_INTERNAL2(GCC diagnostic ignored warningName))
#ifdef __clang__
#define FOLLY_CLANG_DISABLE_WARNING(warningName) \
  FOLLY_GNU_DISABLE_WARNING(warningName)
#define FOLLY_GCC_DISABLE_WARNING(warningName)
#else
#define FOLLY_CLANG_DISABLE_WARNING(warningName)
#define FOLLY_GCC_DISABLE_WARNING(warningName) \
  FOLLY_GNU_DISABLE_WARNING(warningName)
#endif
#define FOLLY_MSVC_DISABLE_WARNING(warningNumber)
#else
#define FOLLY_PUSH_WARNING
#define FOLLY_POP_WARNING
#define FOLLY_GNU_DISABLE_WARNING(warningName)
#define FOLLY_GCC_DISABLE_WARNING(warningName)
#define FOLLY_CLANG_DISABLE_WARNING(warningName)
#define FOLLY_MSVC_DISABLE_WARNING(warningNumber)
#endif

#ifdef FOLLY_HAVE_SHADOW_LOCAL_WARNINGS
#define FOLLY_GCC_DISABLE_NEW_SHADOW_WARNINGS            \
  FOLLY_GNU_DISABLE_WARNING("-Wshadow-compatible-local") \
  FOLLY_GNU_DISABLE_WARNING("-Wshadow-local")            \
  FOLLY_GNU_DISABLE_WARNING("-Wshadow")
#else
#define FOLLY_GCC_DISABLE_NEW_SHADOW_WARNINGS /* empty */
#endif

// Globally disable -Wshadow for gcc < 5.
#if __GNUC__ == 4 && !__clang__
FOLLY_GCC_DISABLE_NEW_SHADOW_WARNINGS
#endif

/* Platform specific TLS support
 * gcc implements __thread
 * msvc implements __declspec(thread)
 * the semantics are the same
 * (but remember __thread has different semantics when using emutls (ex. apple))
 */
#if defined(_MSC_VER)
#define FOLLY_TLS __declspec(thread)
#elif defined(__GNUC__) || defined(__clang__)
#define FOLLY_TLS __thread
#else
#error cannot define platform specific thread local storage
#endif

#if FOLLY_MOBILE
#undef FOLLY_TLS
#endif

// It turns out that GNU libstdc++ and LLVM libc++ differ on how they implement
// the 'std' namespace; the latter uses inline namespaces. Wrap this decision
// up in a macro to make forward-declarations easier.
#if FOLLY_USE_LIBCPP
#include <__config> // @manual
#define FOLLY_NAMESPACE_STD_BEGIN _LIBCPP_BEGIN_NAMESPACE_STD
#define FOLLY_NAMESPACE_STD_END _LIBCPP_END_NAMESPACE_STD
#else
#define FOLLY_NAMESPACE_STD_BEGIN namespace std {
#define FOLLY_NAMESPACE_STD_END }
#endif

// If the new c++ ABI is used, __cxx11 inline namespace needs to be added to
// some types, e.g. std::list.
#if _GLIBCXX_USE_CXX11_ABI
#define FOLLY_GLIBCXX_NAMESPACE_CXX11_BEGIN \
  inline _GLIBCXX_BEGIN_NAMESPACE_CXX11
#define FOLLY_GLIBCXX_NAMESPACE_CXX11_END _GLIBCXX_END_NAMESPACE_CXX11
#else
#define FOLLY_GLIBCXX_NAMESPACE_CXX11_BEGIN
#define FOLLY_GLIBCXX_NAMESPACE_CXX11_END
#endif

// MSVC specific defines
// mainly for posix compat
#ifdef _MSC_VER
#include <folly/portability/SysTypes.h>

// compiler specific to compiler specific
// nolint
#define __PRETTY_FUNCTION__ __FUNCSIG__

// Hide a GCC specific thing that breaks MSVC if left alone.
#define __extension__

// We have compiler support for the newest of the new, but
// MSVC doesn't tell us that.
#define __SSE4_2__ 1

#endif

// Debug
namespace folly {
#ifdef NDEBUG
constexpr auto kIsDebug = false;
#else
constexpr auto kIsDebug = true;
#endif
} // namespace folly

// Endianness
namespace folly {
#ifdef _MSC_VER
// It's MSVC, so we just have to guess ... and allow an override
#ifdef FOLLY_ENDIAN_BE
constexpr auto kIsLittleEndian = false;
#else
constexpr auto kIsLittleEndian = true;
#endif
#else
constexpr auto kIsLittleEndian = __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__;
#endif
constexpr auto kIsBigEndian = !kIsLittleEndian;
} // namespace folly

#ifndef FOLLY_SSE
#if defined(__SSE4_2__)
#define FOLLY_SSE 4
#define FOLLY_SSE_MINOR 2
#elif defined(__SSE4_1__)
#define FOLLY_SSE 4
#define FOLLY_SSE_MINOR 1
#elif defined(__SSE4__)
#define FOLLY_SSE 4
#define FOLLY_SSE_MINOR 0
#elif defined(__SSE3__)
#define FOLLY_SSE 3
#define FOLLY_SSE_MINOR 0
#elif defined(__SSE2__)
#define FOLLY_SSE 2
#define FOLLY_SSE_MINOR 0
#elif defined(__SSE__)
#define FOLLY_SSE 1
#define FOLLY_SSE_MINOR 0
#else
#define FOLLY_SSE 0
#define FOLLY_SSE_MINOR 0
#endif
#endif

#define FOLLY_SSE_PREREQ(major, minor) \
  (FOLLY_SSE > major || FOLLY_SSE == major && FOLLY_SSE_MINOR >= minor)

#ifndef FOLLY_NEON
#if defined(__ARM_NEON) || defined(__ARM_NEON__)
#define FOLLY_NEON 1
#endif
#endif

#if FOLLY_UNUSUAL_GFLAGS_NAMESPACE
namespace FOLLY_GFLAGS_NAMESPACE {}
namespace gflags {
using namespace FOLLY_GFLAGS_NAMESPACE;
} // namespace gflags
#endif

// for TARGET_OS_IPHONE
#ifdef __APPLE__
#include <TargetConditionals.h> // @manual
#endif

// RTTI may not be enabled for this compilation unit.
#if defined(__GXX_RTTI) || defined(__cpp_rtti) || \
    (defined(_MSC_VER) && defined(_CPPRTTI))
#define FOLLY_HAS_RTTI 1
#endif

#if defined(__APPLE__) || defined(_MSC_VER)
#define FOLLY_STATIC_CTOR_PRIORITY_MAX
#else
// 101 is the highest priority allowed by the init_priority attribute.
// This priority is already used by JEMalloc and other memory allocators so
// we will take the next one.
#define FOLLY_STATIC_CTOR_PRIORITY_MAX __attribute__((__init_priority__(102)))
#endif

namespace folly {

#if __OBJC__
constexpr auto kIsObjC = true;
#else
constexpr auto kIsObjC = false;
#endif

#if FOLLY_MOBILE
constexpr auto kIsMobile = true;
#else
constexpr auto kIsMobile = false;
#endif

#if defined(__linux__) && !FOLLY_MOBILE
constexpr auto kIsLinux = true;
#else
constexpr auto kIsLinux = false;
#endif

#if defined(_WIN32)
constexpr auto kIsWindows = true;
#else
constexpr auto kIsWindows = false;
#endif

#if __GLIBCXX__
constexpr auto kIsGlibcxx = true;
#else
constexpr auto kIsGlibcxx = false;
#endif

#if _LIBCPP_VERSION
constexpr auto kIsLibcpp = true;
#else
constexpr auto kIsLibcpp = false;
#endif

#if FOLLY_USE_LIBSTDCPP
constexpr auto kIsLibstdcpp = true;
#else
constexpr auto kIsLibstdcpp = false;
#endif

#if _MSC_VER
constexpr auto kMscVer = _MSC_VER;
#else
constexpr auto kMscVer = 0;
#endif

#if FOLLY_MICROSOFT_ABI_VER
constexpr auto kMicrosoftAbiVer = FOLLY_MICROSOFT_ABI_VER;
#else
constexpr auto kMicrosoftAbiVer = 0;
#endif

// cpplib is an implementation of the standard library, and is the one typically
// used with the msvc compiler
#if _CPPLIB_VER
constexpr auto kCpplibVer = _CPPLIB_VER;
#else
constexpr auto kCpplibVer = 0;
#endif
} // namespace folly

// Define FOLLY_USE_CPP14_CONSTEXPR to be true if the compiler's C++14
// constexpr support is "good enough".
#ifndef FOLLY_USE_CPP14_CONSTEXPR
#if defined(__clang__)
#define FOLLY_USE_CPP14_CONSTEXPR __cplusplus >= 201300L
#elif defined(__GNUC__)
#define FOLLY_USE_CPP14_CONSTEXPR __cplusplus >= 201304L
#else
#define FOLLY_USE_CPP14_CONSTEXPR 0 // MSVC?
#endif
#endif

#if FOLLY_USE_CPP14_CONSTEXPR
#define FOLLY_CPP14_CONSTEXPR constexpr
#else
#define FOLLY_CPP14_CONSTEXPR inline
#endif

//  MSVC does not permit:
//
//    extern int const num;
//    constexpr int const num = 3;
//
//  Instead:
//
//    extern int const num;
//    FOLLY_STORAGE_CONSTEXPR int const num = 3;
//
//  True for MSVC 2015 and MSVC 2017.
#if _MSC_VER
#define FOLLY_STORAGE_CONSTEXPR
#define FOLLY_STORAGE_CPP14_CONSTEXPR
#else
#if __ICC
#define FOLLY_STORAGE_CONSTEXPR
#else
#define FOLLY_STORAGE_CONSTEXPR constexpr
#endif
#if FOLLY_USE_CPP14_CONSTEXPR
#define FOLLY_STORAGE_CPP14_CONSTEXPR constexpr
#else
#define FOLLY_STORAGE_CPP14_CONSTEXPR
#endif
#endif

#if __cpp_coroutines >= 201703L && __has_include(<experimental/coroutine>)
#define FOLLY_HAS_COROUTINES 1
#elif _MSC_VER && _RESUMABLE_FUNCTIONS_SUPPORTED
#define FOLLY_HAS_COROUTINES 1
#endif

// MSVC 2017.5 && C++17
#if __cpp_noexcept_function_type >= 201510 || \
    (_MSC_FULL_VER >= 191225816 && _MSVC_LANG > 201402)
#define FOLLY_HAVE_NOEXCEPT_FUNCTION_TYPE 1
#endif

// Define FOLLY_HAS_EXCEPTIONS
#if __cpp_exceptions >= 199711 || FOLLY_HAS_FEATURE(cxx_exceptions)
#define FOLLY_HAS_EXCEPTIONS 1
#elif __GNUC__
#if __EXCEPTIONS
#define FOLLY_HAS_EXCEPTIONS 1
#else // __EXCEPTIONS
#define FOLLY_HAS_EXCEPTIONS 0
#endif // __EXCEPTIONS
#elif FOLLY_MICROSOFT_ABI_VER
#if _CPPUNWIND
#define FOLLY_HAS_EXCEPTIONS 1
#else // _CPPUNWIND
#define FOLLY_HAS_EXCEPTIONS 0
#endif // _CPPUNWIND
#else
#define FOLLY_HAS_EXCEPTIONS 1 // default assumption for unknown platforms
#endif

// feature test __cpp_lib_string_view is defined in <string>, which is
// too heavy to include here.  MSVC __has_include support arrived later
// than string_view, so we need an alternate case for it.
#ifdef __has_include
#if __has_include(<string_view>) && __cplusplus >= 201703L
#define FOLLY_HAS_STRING_VIEW 1
#else
#define FOLLY_HAS_STRING_VIEW 0
#endif
#else // __has_include
#if _MSC_VER >= 1910 && (_MSVC_LANG > 201402 || __cplusplus > 201402)
#define FOLLY_HAS_STRING_VIEW 1
#else
#define FOLLY_HAS_STRING_VIEW 0
#endif
#endif // __has_include