LXR linux/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)
  18extern void __chk_user_ptr(const volatile void __user *);
  19extern void __chk_io_ptr(const volatile 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#ifdef __GNUC__
  40#include <linux/compiler-gcc.h>
  41#endif
  42
  43#define notrace __attribute__((no_instrument_function))
  44
  45/* Intel compiler defines __GNUC__. So we will overwrite implementations
  46 * coming from above header files here
  47 */
  48#ifdef __INTEL_COMPILER
  49# include <linux/compiler-intel.h>
  50#endif
  51
  52/*
  53 * Generic compiler-dependent macros required for kernel
  54 * build go below this comment. Actual compiler/compiler version
  55 * specific implementations come from the above header files
  56 */
  57
  58struct ftrace_branch_data {
  59        const char *func;
  60        const char *file;
  61        unsigned line;
  62        union {
  63                struct {
  64                        unsigned long correct;
  65                        unsigned long incorrect;
  66                };
  67                struct {
  68                        unsigned long miss;
  69                        unsigned long hit;
  70                };
  71        };
  72};
  73
  74/*
  75 * Note: DISABLE_BRANCH_PROFILING can be used by special lowlevel code
  76 * to disable branch tracing on a per file basis.
  77 */
  78#if defined(CONFIG_TRACE_BRANCH_PROFILING) && !defined(DISABLE_BRANCH_PROFILING)
  79void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
  80
  81#define likely_notrace(x)       __builtin_expect(!!(x), 1)
  82#define unlikely_notrace(x)     __builtin_expect(!!(x), 0)
  83
  84#define __branch_check__(x, expect) ({                                  \
  85                        int ______r;                                    \
  86                        static struct ftrace_branch_data                \
  87                                __attribute__((__aligned__(4)))         \
  88                                __attribute__((section("_ftrace_annotated_branch"))) \
  89                                ______f = {                             \
  90                                .func = __func__,                       \
  91                                .file = __FILE__,                       \
  92                                .line = __LINE__,                       \
  93                        };                                              \
  94                        ______r = likely_notrace(x);                    \
  95                        ftrace_likely_update(&______f, ______r, expect); \
  96                        ______r;                                        \
  97                })
  98
  99/*
 100 * Using __builtin_constant_p(x) to ignore cases where the return
 101 * value is always the same.  This idea is taken from a similar patch
 102 * written by Daniel Walker.
 103 */
 104# ifndef likely
 105#  define likely(x)     (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 1))
 106# endif
 107# ifndef unlikely
 108#  define unlikely(x)   (__builtin_constant_p(x) ? !!(x) : __branch_check__(x, 0))
 109# endif
 110
 111#ifdef CONFIG_PROFILE_ALL_BRANCHES
 112/*
 113 * "Define 'is'", Bill Clinton
 114 * "Define 'if'", Steven Rostedt
 115 */
 116#define if(cond) if (__builtin_constant_p((cond)) ? !!(cond) :          \
 117        ({                                                              \
 118                int ______r;                                            \
 119                static struct ftrace_branch_data                        \
 120                        __attribute__((__aligned__(4)))                 \
 121                        __attribute__((section("_ftrace_branch")))      \
 122                        ______f = {                                     \
 123                                .func = __func__,                       \
 124                                .file = __FILE__,                       \
 125                                .line = __LINE__,                       \
 126                        };                                              \
 127                ______r = !!(cond);                                     \
 128                if (______r)                                            \
 129                        ______f.hit++;                                  \
 130                else                                                    \
 131                        ______f.miss++;                                 \
 132                ______r;                                                \
 133        }))
 134#endif /* CONFIG_PROFILE_ALL_BRANCHES */
 135
 136#else
 137# define likely(x)      __builtin_expect(!!(x), 1)
 138# define unlikely(x)    __builtin_expect(!!(x), 0)
 139#endif
 140
 141/* Optimization barrier */
 142#ifndef barrier
 143# define barrier() __memory_barrier()
 144#endif
 145
 146#ifndef RELOC_HIDE
 147# define RELOC_HIDE(ptr, off)                                   \
 148  ({ unsigned long __ptr;                                       \
 149     __ptr = (unsigned long) (ptr);                             \
 150    (typeof(ptr)) (__ptr + (off)); })
 151#endif
 152
 153#endif /* __KERNEL__ */
 154
 155#endif /* __ASSEMBLY__ */
 156
 157#ifdef __KERNEL__
 158/*
 159 * Allow us to mark functions as 'deprecated' and have gcc emit a nice
 160 * warning for each use, in hopes of speeding the functions removal.
 161 * Usage is:
 162 *              int __deprecated foo(void)
 163 */
 164#ifndef __deprecated
 165# define __deprecated           /* unimplemented */
 166#endif
 167
 168#ifdef MODULE
 169#define __deprecated_for_modules __deprecated
 170#else
 171#define __deprecated_for_modules
 172#endif
 173
 174#ifndef __must_check
 175#define __must_check
 176#endif
 177
 178#ifndef CONFIG_ENABLE_MUST_CHECK
 179#undef __must_check
 180#define __must_check
 181#endif
 182#ifndef CONFIG_ENABLE_WARN_DEPRECATED
 183#undef __deprecated
 184#undef __deprecated_for_modules
 185#define __deprecated
 186#define __deprecated_for_modules
 187#endif
 188
 189/*
 190 * Allow us to avoid 'defined but not used' warnings on functions and data,
 191 * as well as force them to be emitted to the assembly file.
 192 *
 193 * As of gcc 3.4, static functions that are not marked with attribute((used))
 194 * may be elided from the assembly file.  As of gcc 3.4, static data not so
 195 * marked will not be elided, but this may change in a future gcc version.
 196 *
 197 * NOTE: Because distributions shipped with a backported unit-at-a-time
 198 * compiler in gcc 3.3, we must define __used to be __attribute__((used))
 199 * for gcc >=3.3 instead of 3.4.
 200 *
 201 * In prior versions of gcc, such functions and data would be emitted, but
 202 * would be warned about except with attribute((unused)).
 203 *
 204 * Mark functions that are referenced only in inline assembly as __used so
 205 * the code is emitted even though it appears to be unreferenced.
 206 */
 207#ifndef __used
 208# define __used                 /* unimplemented */
 209#endif
 210
 211#ifndef __maybe_unused
 212# define __maybe_unused         /* unimplemented */
 213#endif
 214
 215#ifndef noinline
 216#define noinline
 217#endif
 218
 219/*
 220 * Rather then using noinline to prevent stack consumption, use
 221 * noinline_for_stack instead.  For documentaiton reasons.
 222 */
 223#define noinline_for_stack noinline
 224
 225#ifndef __always_inline
 226#define __always_inline inline
 227#endif
 228
 229#endif /* __KERNEL__ */
 230
 231/*
 232 * From the GCC manual:
 233 *
 234 * Many functions do not examine any values except their arguments,
 235 * and have no effects except the return value.  Basically this is
 236 * just slightly more strict class than the `pure' attribute above,
 237 * since function is not allowed to read global memory.
 238 *
 239 * Note that a function that has pointer arguments and examines the
 240 * data pointed to must _not_ be declared `const'.  Likewise, a
 241 * function that calls a non-`const' function usually must not be
 242 * `const'.  It does not make sense for a `const' function to return
 243 * `void'.
 244 */
 245#ifndef __attribute_const__
 246# define __attribute_const__    /* unimplemented */
 247#endif
 248
 249/*
 250 * Tell gcc if a function is cold. The compiler will assume any path
 251 * directly leading to the call is unlikely.
 252 */
 253
 254#ifndef __cold
 255#define __cold
 256#endif
 257
 258/* Simple shorthand for a section definition */
 259#ifndef __section
 260# define __section(S) __attribute__ ((__section__(#S)))
 261#endif
 262
 263/*
 264 * Prevent the compiler from merging or refetching accesses.  The compiler
 265 * is also forbidden from reordering successive instances of ACCESS_ONCE(),
 266 * but only when the compiler is aware of some particular ordering.  One way
 267 * to make the compiler aware of ordering is to put the two invocations of
 268 * ACCESS_ONCE() in different C statements.
 269 *
 270 * This macro does absolutely -nothing- to prevent the CPU from reordering,
 271 * merging, or refetching absolutely anything at any time.  Its main intended
 272 * use is to mediate communication between process-level code and irq/NMI
 273 * handlers, all running on the same CPU.
 274 */
 275#define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
 276
 277#endif /* __LINUX_COMPILER_H */
 278