include/linux/compiler-gcc4.h

   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 #define __always_inline         inline __attribute__((always_inline))
  16
  17 /*
  18  * A trick to suppress uninitialized variable warning without generating any
  19  * code
  20  */
  21 #define uninitialized_var(x) x = x
  22
  23 #if __GNUC_MINOR__ >= 3
  24 /* Mark functions as cold. gcc will assume any path leading to a call
  25    to them will be unlikely.  This means a lot of manual unlikely()s
  26    are unnecessary now for any paths leading to the usual suspects
  27    like BUG(), printk(), panic() etc. [but let's keep them for now for
  28    older compilers]
  29
  30    Early snapshots of gcc 4.3 don't support this and we can't detect this
  31    in the preprocessor, but we can live with this because they're unreleased.
  32    Maketime probing would be overkill here.
  33
  34    gcc also has a __attribute__((__hot__)) to move hot functions into
  35    a special section, but I don't see any sense in this right now in
  36    the kernel context */
  37 #define __cold                  __attribute__((__cold__))
  38
  39
  40 #if __GNUC_MINOR__ >= 5
  41 /*
  42  * Mark a position in code as unreachable.  This can be used to
  43  * suppress control flow warnings after asm blocks that transfer
  44  * control elsewhere.
  45  *
  46  * Early snapshots of gcc 4.5 don't support this and we can't detect
  47  * this in the preprocessor, but we can live with this because they're
  48  * unreleased.  Really, we need to have autoconf for the kernel.
  49  */
  50 #define unreachable() __builtin_unreachable()
  51 #endif
  52
  53 #endif
  54
  55 #if __GNUC_MINOR__ > 0
  56 #define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
  57 #endif
  58 #if __GNUC_MINOR__ >= 4
  59 #define __compiletime_warning(message) __attribute__((warning(message)))
  60 #define __compiletime_error(message) __attribute__((error(message)))
  61 #endif