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FFmpeg/libavutil/attributes.h
Martin Storsjö f637046d31 libavutil: Always use some GCC style attributes on clang
Clang normally disguises as GCC (defining __GNUC__), and thus get
all the normal GCC specific attributes.

Clang can also work as a drop-in replacement for MSVC, and in these
cases, it doesn't define __GNUC__, but defines _MSC_VER instead.

Even in these setups, it still supports the GCC style attributes,
thus use them, especially where there isn't any MSVC specific
version, or where the MSVC specific version doesn't work on clang
(for DECLARE_ASM_CONST).

Signed-off-by: Martin Storsjö <martin@martin.st>
2016-07-21 12:52:19 +03:00

127 lines
3.3 KiB
C

/*
* copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* Macro definitions for various function/variable attributes
*/
#ifndef AVUTIL_ATTRIBUTES_H
#define AVUTIL_ATTRIBUTES_H
#ifdef __GNUC__
# define AV_GCC_VERSION_AT_LEAST(x,y) (__GNUC__ > x || __GNUC__ == x && __GNUC_MINOR__ >= y)
#else
# define AV_GCC_VERSION_AT_LEAST(x,y) 0
#endif
#if AV_GCC_VERSION_AT_LEAST(3,1)
# define av_always_inline __attribute__((always_inline)) inline
#elif defined(_MSC_VER)
# define av_always_inline __forceinline
#else
# define av_always_inline inline
#endif
#if AV_GCC_VERSION_AT_LEAST(3,1)
# define av_noinline __attribute__((noinline))
#elif defined(_MSC_VER)
# define av_noinline __declspec(noinline)
#else
# define av_noinline
#endif
#if AV_GCC_VERSION_AT_LEAST(3,1)
# define av_pure __attribute__((pure))
#else
# define av_pure
#endif
#if AV_GCC_VERSION_AT_LEAST(2,6)
# define av_const __attribute__((const))
#else
# define av_const
#endif
#if AV_GCC_VERSION_AT_LEAST(4,3)
# define av_cold __attribute__((cold))
#else
# define av_cold
#endif
#if AV_GCC_VERSION_AT_LEAST(4,1) && !defined(__llvm__)
# define av_flatten __attribute__((flatten))
#else
# define av_flatten
#endif
#if AV_GCC_VERSION_AT_LEAST(3,1)
# define attribute_deprecated __attribute__((deprecated))
#elif defined(_MSC_VER)
# define attribute_deprecated __declspec(deprecated)
#else
# define attribute_deprecated
#endif
#if defined(__GNUC__) || defined(__clang__)
# define av_unused __attribute__((unused))
#else
# define av_unused
#endif
/**
* Mark a variable as used and prevent the compiler from optimizing it
* away. This is useful for variables accessed only from inline
* assembler without the compiler being aware.
*/
#if AV_GCC_VERSION_AT_LEAST(3,1) || defined(__clang__)
# define av_used __attribute__((used))
#else
# define av_used
#endif
#if AV_GCC_VERSION_AT_LEAST(3,3)
# define av_alias __attribute__((may_alias))
#else
# define av_alias
#endif
#if defined(__GNUC__) && !defined(__ICC)
# define av_uninit(x) x=x
#else
# define av_uninit(x) x
#endif
#ifdef __GNUC__
# define av_builtin_constant_p __builtin_constant_p
# define av_printf_format(fmtpos, attrpos) __attribute__((__format__(__printf__, fmtpos, attrpos)))
#else
# define av_builtin_constant_p(x) 0
# define av_printf_format(fmtpos, attrpos)
#endif
#if AV_GCC_VERSION_AT_LEAST(2,5)
# define av_noreturn __attribute__((noreturn))
#else
# define av_noreturn
#endif
#endif /* AVUTIL_ATTRIBUTES_H */