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 GCC_VERSION >= 40100 &&  GCC_VERSION <= 40101
   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 GCC_VERSION >= 40100
  17# define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
  18#endif
  19
  20#if GCC_VERSION >= 40300
  21/* Mark functions as cold. gcc will assume any path leading to a call
  22   to them will be unlikely.  This means a lot of manual unlikely()s
  23   are unnecessary now for any paths leading to the usual suspects
  24   like BUG(), printk(), panic() etc. [but let's keep them for now for
  25   older compilers]
  26
  27   Early snapshots of gcc 4.3 don't support this and we can't detect this
  28   in the preprocessor, but we can live with this because they're unreleased.
  29   Maketime probing would be overkill here.
  30
  31   gcc also has a __attribute__((__hot__)) to move hot functions into
  32   a special section, but I don't see any sense in this right now in
  33   the kernel context */
  34#define __cold                  __attribute__((__cold__))
  35
  36#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
  37
  38#ifndef __CHECKER__
  39# define __compiletime_warning(message) __attribute__((warning(message)))
  40# define __compiletime_error(message) __attribute__((error(message)))
  41#endif /* __CHECKER__ */
  42#endif /* GCC_VERSION >= 40300 */
  43
  44#if GCC_VERSION >= 40500
  45/*
  46 * Mark a position in code as unreachable.  This can be used to
  47 * suppress control flow warnings after asm blocks that transfer
  48 * control elsewhere.
  49 *
  50 * Early snapshots of gcc 4.5 don't support this and we can't detect
  51 * this in the preprocessor, but we can live with this because they're
  52 * unreleased.  Really, we need to have autoconf for the kernel.
  53 */
  54#define unreachable() __builtin_unreachable()
  55
  56/* Mark a function definition as prohibited from being cloned. */
  57#define __noclone       __attribute__((__noclone__))
  58
  59#endif /* GCC_VERSION >= 40500 */
  60
  61#if GCC_VERSION >= 40600
  62/*
  63 * Tell the optimizer that something else uses this function or variable.
  64 */
  65#define __visible __attribute__((externally_visible))
  66#endif
  67
  68
  69#ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
  70#if GCC_VERSION >= 40400
  71#define __HAVE_BUILTIN_BSWAP32__
  72#define __HAVE_BUILTIN_BSWAP64__
  73#endif
  74#if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600)
  75#define __HAVE_BUILTIN_BSWAP16__
  76#endif
  77#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
  78
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