LXR linux/include/linux/compiler-gcc.h

   1#ifndef __LINUX_COMPILER_H
   2#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
   3#endif
   4
   5/*
   6 * Common definitions for all gcc versions go here.
   7 */
   8
   9
  10/* Optimization barrier */
  11/* The "volatile" is due to gcc bugs */
  12#define barrier() __asm__ __volatile__("": : :"memory")
  13
  14/* This macro obfuscates arithmetic on a variable address so that gcc
  15   shouldn't recognize the original var, and make assumptions about it */
  16/*
  17 * Versions of the ppc64 compiler before 4.1 had a bug where use of
  18 * RELOC_HIDE could trash r30. The bug can be worked around by changing
  19 * the inline assembly constraint from =g to =r, in this particular
  20 * case either is valid.
  21 */
  22#define RELOC_HIDE(ptr, off)                                    \
  23  ({ unsigned long __ptr;                                       \
  24    __asm__ ("" : "=r"(__ptr) : "0"(ptr));              \
  25    (typeof(ptr)) (__ptr + (off)); })
  26
  27/* &a[0] degrades to a pointer: a different type from an array */
  28#define __must_be_array(a) \
  29  BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(typeof(a), typeof(&a[0])))
  30
  31/*
  32 * Force always-inline if the user requests it so via the .config,
  33 * or if gcc is too old:
  34 */
  35#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
  36    !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
  37# define inline         inline          __attribute__((always_inline))
  38# define __inline__     __inline__      __attribute__((always_inline))
  39# define __inline       __inline        __attribute__((always_inline))
  40#endif
  41
  42#define __deprecated                    __attribute__((deprecated))
  43#define __packed                        __attribute__((packed))
  44#define __weak                          __attribute__((weak))
  45#define __naked                         __attribute__((naked))
  46#define __noreturn                      __attribute__((noreturn))
  47
  48/*
  49 * From the GCC manual:
  50 *
  51 * Many functions have no effects except the return value and their
  52 * return value depends only on the parameters and/or global
  53 * variables.  Such a function can be subject to common subexpression
  54 * elimination and loop optimization just as an arithmetic operator
  55 * would be.
  56 * [...]
  57 */
  58#define __pure                          __attribute__((pure))
  59#define __aligned(x)                    __attribute__((aligned(x)))
  60#define __printf(a,b)                   __attribute__((format(printf,a,b)))
  61#define  noinline                       __attribute__((noinline))
  62#define __attribute_const__             __attribute__((__const__))
  63#define __maybe_unused                  __attribute__((unused))
  64