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linux-next/include/linux/compiler-gcc4.h
Linus Torvalds ae3e462828 Merge branch 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild
Pull kbuild changes from Michal Marek:
 "The main part of kbuild for v3.7 contains:
   - Fix for scripts/Makefile.modpost to not choke on a '.ko' substring
     in the build directory path
   - Two warning fixes (modpost and main Makefile)
   - __compiletime_error works also with gcc 4.3
   - make tar{gz,bz2,xz}-pkg uses default compression settings instead
     of saving as many bytes as possible (this should actually be in the
     misc branch, I don't know why I applied it here)."

* 'kbuild' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild:
  compiler-gcc4.h: correct verion check for __compiletime_error
  modpost: Permit .GCC.command.line sections
  Kbuild: use normal compression settings for tar*-pkg
  scripts/Makefile.modpost: error in finding modules from .mod files.
  kbuild: Remove useless warning while appending KCFLAGS
2012-10-12 10:27:27 +09:00

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C

#ifndef __LINUX_COMPILER_H
#error "Please don't include <linux/compiler-gcc4.h> directly, include <linux/compiler.h> instead."
#endif
/* GCC 4.1.[01] miscompiles __weak */
#ifdef __KERNEL__
# if __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ <= 1
# error Your version of gcc miscompiles the __weak directive
# endif
#endif
#define __used __attribute__((__used__))
#define __must_check __attribute__((warn_unused_result))
#define __compiler_offsetof(a,b) __builtin_offsetof(a,b)
#if __GNUC_MINOR__ >= 3
/* Mark functions as cold. gcc will assume any path leading to a call
to them will be unlikely. This means a lot of manual unlikely()s
are unnecessary now for any paths leading to the usual suspects
like BUG(), printk(), panic() etc. [but let's keep them for now for
older compilers]
Early snapshots of gcc 4.3 don't support this and we can't detect this
in the preprocessor, but we can live with this because they're unreleased.
Maketime probing would be overkill here.
gcc also has a __attribute__((__hot__)) to move hot functions into
a special section, but I don't see any sense in this right now in
the kernel context */
#define __cold __attribute__((__cold__))
#define __linktime_error(message) __attribute__((__error__(message)))
#if __GNUC_MINOR__ >= 5
/*
* Mark a position in code as unreachable. This can be used to
* suppress control flow warnings after asm blocks that transfer
* control elsewhere.
*
* Early snapshots of gcc 4.5 don't support this and we can't detect
* this in the preprocessor, but we can live with this because they're
* unreleased. Really, we need to have autoconf for the kernel.
*/
#define unreachable() __builtin_unreachable()
/* Mark a function definition as prohibited from being cloned. */
#define __noclone __attribute__((__noclone__))
#endif
#endif
#if __GNUC_MINOR__ >= 6
/*
* Tell the optimizer that something else uses this function or variable.
*/
#define __visible __attribute__((externally_visible))
#endif
#if __GNUC_MINOR__ > 0
#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
#endif
#if __GNUC_MINOR__ >= 3 && !defined(__CHECKER__)
#define __compiletime_warning(message) __attribute__((warning(message)))
#define __compiletime_error(message) __attribute__((error(message)))
#endif