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))