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  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. /*
  15.  * This macro obfuscates arithmetic on a variable address so that gcc
  16.  * shouldn't recognize the original var, and make assumptions about it.
  17.  *
  18.  * This is needed because the C standard makes it undefined to do
  19.  * pointer arithmetic on "objects" outside their boundaries and the
  20.  * gcc optimizers assume this is the case. In particular they
  21.  * assume such arithmetic does not wrap.
  22.  *
  23.  * A miscompilation has been observed because of this on PPC.
  24.  * To work around it we hide the relationship of the pointer and the object
  25.  * using this macro.
  26.  *
  27.  * Versions of the ppc64 compiler before 4.1 had a bug where use of
  28.  * RELOC_HIDE could trash r30. The bug can be worked around by changing
  29.  * the inline assembly constraint from =g to =r, in this particular
  30.  * case either is valid.
  31.  */
  32. #define RELOC_HIDE(ptr, off)                                    \
  33.   ({ unsigned long __ptr;                                       \
  34.     __asm__ ("" : "=r"(__ptr) : "0"(ptr));              \
  35.     (typeof(ptr)) (__ptr + (off)); })
  36.  
  37. /* &a[0] degrades to a pointer: a different type from an array */
  38. #define __must_be_array(a) \
  39.   BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(typeof(a), typeof(&a[0])))
  40.  
  41. /*
  42.  * Force always-inline if the user requests it so via the .config,
  43.  * or if gcc is too old:
  44.  */
  45. #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
  46.     !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
  47. # define inline         inline          __attribute__((always_inline))
  48. # define __inline__     __inline__      __attribute__((always_inline))
  49. # define __inline       __inline        __attribute__((always_inline))
  50. #endif
  51.  
  52. #define __deprecated                    __attribute__((deprecated))
  53. #define __packed                        __attribute__((packed))
  54. #define __weak                          __attribute__((weak))
  55.  
  56. /*
  57.  * it doesn't make sense on ARM (currently the only user of __naked) to trace
  58.  * naked functions because then mcount is called without stack and frame pointer
  59.  * being set up and there is no chance to restore the lr register to the value
  60.  * before mcount was called.
  61.  */
  62. #define __naked                         __attribute__((naked)) notrace
  63.  
  64. #define __noreturn                      __attribute__((noreturn))
  65.  
  66. /*
  67.  * From the GCC manual:
  68.  *
  69.  * Many functions have no effects except the return value and their
  70.  * return value depends only on the parameters and/or global
  71.  * variables.  Such a function can be subject to common subexpression
  72.  * elimination and loop optimization just as an arithmetic operator
  73.  * would be.
  74.  * [...]
  75.  */
  76. #define __pure                          __attribute__((pure))
  77. #define __aligned(x)                    __attribute__((aligned(x)))
  78. #define __printf(a,b)                   __attribute__((format(printf,a,b)))
  79. #define  noinline                       __attribute__((noinline))
  80. #define __attribute_const__             __attribute__((__const__))
  81. #define __maybe_unused                  __attribute__((unused))
  82. #define __always_unused                 __attribute__((unused))
  83.  
  84. #define __gcc_header(x) #x
  85. #define _gcc_header(x) __gcc_header(linux/compiler-gcc##x.h)
  86. #define gcc_header(x) _gcc_header(x)
  87. #include gcc_header(__GNUC__)
  88.