include/linux/compiler.h

   1 #ifndef __LINUX_COMPILER_H
   2 #define __LINUX_COMPILER_H
   3
   4 #ifndef __ASSEMBLY__
   5
   6 #ifdef __CHECKER__
   7 # define __user         __attribute__((noderef, address_space(1)))
   8 # define __kernel       /* default address space */
   9 # define __safe         __attribute__((safe))
  10 # define __force        __attribute__((force))
  11 # define __nocast       __attribute__((nocast))
  12 # define __iomem        __attribute__((noderef, address_space(2)))
  13 # define __acquires(x)  __attribute__((context(x,0,1)))
  14 # define __releases(x)  __attribute__((context(x,1,0)))
  15 # define __acquire(x)   __context__(x,1)
  16 # define __release(x)   __context__(x,-1)
  17 # define __cond_lock(x,c)       ((c) ? ({ __acquire(x); 1; }) : 0)
  18 extern void __chk_user_ptr(const void __user *);
  19 extern void __chk_io_ptr(const void __iomem *);
  20 #else
  21 # define __user
  22 # define __kernel
  23 # define __safe
  24 # define __force
  25 # define __nocast
  26 # define __iomem
  27 # define __chk_user_ptr(x) (void)0
  28 # define __chk_io_ptr(x) (void)0
  29 # define __builtin_warning(x, y...) (1)
  30 # define __acquires(x)
  31 # define __releases(x)
  32 # define __acquire(x) (void)0
  33 # define __release(x) (void)0
  34 # define __cond_lock(x,c) (c)
  35 #endif
  36
  37 #ifdef __KERNEL__
  38
  39 #if __GNUC__ > 4
  40 #error no compiler-gcc.h file for this gcc version
  41 #elif __GNUC__ == 4
  42 # include <linux/compiler-gcc4.h>
  43 #elif __GNUC__ == 3 && __GNUC_MINOR__ >= 2
  44 # include <linux/compiler-gcc3.h>
  45 #else
  46 # error Sorry, your compiler is too old/not recognized.
  47 #endif
  48
  49 /* Intel compiler defines __GNUC__. So we will overwrite implementations
  50  * coming from above header files here
  51  */
  52 #ifdef __INTEL_COMPILER
  53 # include <linux/compiler-intel.h>
  54 #endif
  55
  56 /*
  57  * Generic compiler-dependent macros required for kernel
  58  * build go below this comment. Actual compiler/compiler version
  59  * specific implementations come from the above header files
  60  */
  61
  62 #define likely(x)       __builtin_expect(!!(x), 1)
  63 #define unlikely(x)     __builtin_expect(!!(x), 0)
  64
  65 /* Optimization barrier */
  66 #ifndef barrier
  67 # define barrier() __memory_barrier()
  68 #endif
  69
  70 #ifndef RELOC_HIDE
  71 # define RELOC_HIDE(ptr, off)                                   \
  72   ({ unsigned long __ptr;                                       \
  73      __ptr = (unsigned long) (ptr);                             \
  74     (typeof(ptr)) (__ptr + (off)); })
  75 #endif
  76
  77 #endif /* __KERNEL__ */
  78
  79 #endif /* __ASSEMBLY__ */
  80
  81 #ifdef __KERNEL__
  82 /*
  83  * Allow us to mark functions as 'deprecated' and have gcc emit a nice
  84  * warning for each use, in hopes of speeding the functions removal.
  85  * Usage is:
  86  *              int __deprecated foo(void)
  87  */
  88 #ifndef __deprecated
  89 # define __deprecated           /* unimplemented */
  90 #endif
  91
  92 #ifdef MODULE
  93 #define __deprecated_for_modules __deprecated
  94 #else
  95 #define __deprecated_for_modules
  96 #endif
  97
  98 #ifndef __must_check
  99 #define __must_check
 100 #endif
 101
 102 #ifndef CONFIG_ENABLE_MUST_CHECK
 103 #undef __must_check
 104 #define __must_check
 105 #endif
 106
 107 /*
 108  * Allow us to avoid 'defined but not used' warnings on functions and data,
 109  * as well as force them to be emitted to the assembly file.
 110  *
 111  * As of gcc 3.4, static functions that are not marked with attribute((used))
 112  * may be elided from the assembly file.  As of gcc 3.4, static data not so
 113  * marked will not be elided, but this may change in a future gcc version.
 114  *
 115  * NOTE: Because distributions shipped with a backported unit-at-a-time
 116  * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 117  * for gcc >=3.3 instead of 3.4.
 118  *
 119  * In prior versions of gcc, such functions and data would be emitted, but
 120  * would be warned about except with attribute((unused)).
 121  *
 122  * Mark functions that are referenced only in inline assembly as __used so
 123  * the code is emitted even though it appears to be unreferenced.
 124  */
 125 #ifndef __attribute_used__
 126 # define __attribute_used__     /* deprecated */
 127 #endif
 128
 129 #ifndef __used
 130 # define __used                 /* unimplemented */
 131 #endif
 132
 133 #ifndef __maybe_unused
 134 # define __maybe_unused         /* unimplemented */
 135 #endif
 136
 137 /*
 138  * From the GCC manual:
 139  *
 140  * Many functions have no effects except the return value and their
 141  * return value depends only on the parameters and/or global
 142  * variables.  Such a function can be subject to common subexpression
 143  * elimination and loop optimization just as an arithmetic operator
 144  * would be.
 145  * [...]
 146  */
 147 #ifndef __attribute_pure__
 148 # define __attribute_pure__     /* unimplemented */
 149 #endif
 150
 151 #ifndef noinline
 152 #define noinline
 153 #endif
 154
 155 #ifndef __always_inline
 156 #define __always_inline inline
 157 #endif
 158
 159 #endif /* __KERNEL__ */
 160
 161 /*
 162  * From the GCC manual:
 163  *
 164  * Many functions do not examine any values except their arguments,
 165  * and have no effects except the return value.  Basically this is
 166  * just slightly more strict class than the `pure' attribute above,
 167  * since function is not allowed to read global memory.
 168  *
 169  * Note that a function that has pointer arguments and examines the
 170  * data pointed to must _not_ be declared `const'.  Likewise, a
 171  * function that calls a non-`const' function usually must not be
 172  * `const'.  It does not make sense for a `const' function to return
 173  * `void'.
 174  */
 175 #ifndef __attribute_const__
 176 # define __attribute_const__    /* unimplemented */
 177 #endif
 178
 179 #endif /* __LINUX_COMPILER_H */