linux/include/linux/compiler-gcc4.h
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   1#ifndef __LINUX_COMPILER_H
   2#error "Please don't include <linux/compiler-gcc4.h> directly, include <linux/compiler.h> instead."
   3#endif
   4
   5/* GCC 4.1.[01] miscompiles __weak */
   6#ifdef __KERNEL__
   7# if __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ <= 1
   8#  error Your version of gcc miscompiles the __weak directive
   9# endif
  10#endif
  11
  12#define __used                  __attribute__((__used__))
  13#define __must_check            __attribute__((warn_unused_result))
  14#define __compiler_offsetof(a,b) __builtin_offsetof(a,b)
  15
  16#if __GNUC_MINOR__ >= 3
  17/* Mark functions as cold. gcc will assume any path leading to a call
  18   to them will be unlikely.  This means a lot of manual unlikely()s
  19   are unnecessary now for any paths leading to the usual suspects
  20   like BUG(), printk(), panic() etc. [but let's keep them for now for
  21   older compilers]
  22
  23   Early snapshots of gcc 4.3 don't support this and we can't detect this
  24   in the preprocessor, but we can live with this because they're unreleased.
  25   Maketime probing would be overkill here.
  26
  27   gcc also has a __attribute__((__hot__)) to move hot functions into
  28   a special section, but I don't see any sense in this right now in
  29   the kernel context */
  30#define __cold                  __attribute__((__cold__))
  31
  32#define __linktime_error(message) __attribute__((__error__(message)))
  33
  34#if __GNUC_MINOR__ >= 5
  35/*
  36 * Mark a position in code as unreachable.  This can be used to
  37 * suppress control flow warnings after asm blocks that transfer
  38 * control elsewhere.
  39 *
  40 * Early snapshots of gcc 4.5 don't support this and we can't detect
  41 * this in the preprocessor, but we can live with this because they're
  42 * unreleased.  Really, we need to have autoconf for the kernel.
  43 */
  44#define unreachable() __builtin_unreachable()
  45
  46/* Mark a function definition as prohibited from being cloned. */
  47#define __noclone       __attribute__((__noclone__))
  48
  49#endif
  50#endif
  51
  52#if __GNUC_MINOR__ >= 6
  53/*
  54 * Tell the optimizer that something else uses this function or variable.
  55 */
  56#define __visible __attribute__((externally_visible))
  57#endif
  58
  59#if __GNUC_MINOR__ > 0
  60#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
  61#endif
  62#if __GNUC_MINOR__ >= 4 && !defined(__CHECKER__)
  63#define __compiletime_warning(message) __attribute__((warning(message)))
  64#define __compiletime_error(message) __attribute__((error(message)))
  65#endif
  66
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