File: /Users/paulross/dev/linux/linux-3.13/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 && GCC_VERSION < 40600
      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:  * GCC 'asm goto' miscompiles certain code sequences:
      70:  *
      71:  *   http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58670
      72:  *
      73:  * Work it around via a compiler barrier quirk suggested by Jakub Jelinek.
      74:  * Fixed in GCC 4.8.2 and later versions.
      75:  *
      76:  * (asm goto is automatically volatile - the naming reflects this.)
      77:  */
      78: #if GCC_VERSION <= 40801
      79: # define asm_volatile_goto(x...)    do { asm goto(x); asm (""); } while (0)
      80: #else
      81: # define asm_volatile_goto(x...)    do { asm goto(x); } while (0)
      82: #endif
      83: 
      84: #ifdef CONFIG_ARCH_USE_BUILTIN_BSWAP
      85: #if GCC_VERSION >= 40400
      86: #define __HAVE_BUILTIN_BSWAP32__
      87: #define __HAVE_BUILTIN_BSWAP64__
      88: #endif
      89: #if GCC_VERSION >= 40800 || (defined(__powerpc__) && GCC_VERSION >= 40600)
      90: #define __HAVE_BUILTIN_BSWAP16__
      91: #endif
      92: #endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
      93: