src/util/macros.h

   1 /*
   2  * Copyright © 2014 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  */
  23
  24 #ifndef UTIL_MACROS_H
  25 #define UTIL_MACROS_H
  26
  27 /* Compute the size of an array */
  28 #ifndef ARRAY_SIZE
  29 #  define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
  30 #endif
  31
  32
  33 /**
  34  * __builtin_expect macros
  35  */
  36 #if !defined(HAVE___BUILTIN_EXPECT)
  37 #  define __builtin_expect(x, y) (x)
  38 #endif
  39
  40 #ifndef likely
  41 #  ifdef HAVE___BUILTIN_EXPECT
  42 #    define likely(x)   __builtin_expect(!!(x), 1)
  43 #    define unlikely(x) __builtin_expect(!!(x), 0)
  44 #  else
  45 #    define likely(x)   (x)
  46 #    define unlikely(x) (x)
  47 #  endif
  48 #endif
  49
  50
  51 /**
  52  * Static (compile-time) assertion.
  53  * Basically, use COND to dimension an array.  If COND is false/zero the
  54  * array size will be -1 and we'll get a compilation error.
  55  */
  56 #define STATIC_ASSERT(COND) \
  57    do { \
  58       (void) sizeof(char [1 - 2*!(COND)]); \
  59    } while (0)
  60
  61
  62 /**
  63  * Unreachable macro. Useful for suppressing "control reaches end of non-void
  64  * function" warnings.
  65  */
  66 #ifdef HAVE___BUILTIN_UNREACHABLE
  67 #define unreachable(str)    \
  68 do {                        \
  69    assert(!str);            \
  70    __builtin_unreachable(); \
  71 } while (0)
  72 #elif _MSC_VER >= 1200
  73 #define unreachable(str)    \
  74 do {                        \
  75    assert(!str);            \
  76    __assume(0);             \
  77 } while (0)
  78 #endif
  79
  80 #ifndef unreachable
  81 #define unreachable(str)
  82 #endif
  83
  84 /**
  85  * Assume macro. Useful for expressing our assumptions to the compiler,
  86  * typically for purposes of silencing warnings.
  87  */
  88 #ifdef HAVE___BUILTIN_UNREACHABLE
  89 #define assume(expr) ((expr) ? ((void) 0) \
  90                              : (assert(!"assumption failed"), \
  91                                 __builtin_unreachable()))
  92 #elif _MSC_VER >= 1200
  93 #define assume(expr) __assume(expr)
  94 #else
  95 #define assume(expr) assert(expr)
  96 #endif
  97
  98 #ifdef HAVE_FUNC_ATTRIBUTE_FLATTEN
  99 #define FLATTEN __attribute__((__flatten__))
 100 #else
 101 #define FLATTEN
 102 #endif
 103
 104 #ifdef HAVE_FUNC_ATTRIBUTE_FORMAT
 105 #define PRINTFLIKE(f, a) __attribute__ ((format(__printf__, f, a)))
 106 #else
 107 #define PRINTFLIKE(f, a)
 108 #endif
 109
 110 #ifdef HAVE_FUNC_ATTRIBUTE_MALLOC
 111 #define MALLOCLIKE __attribute__((__malloc__))
 112 #else
 113 #define MALLOCLIKE
 114 #endif
 115
 116 /* Used to optionally mark structures with misaligned elements or size as
 117  * packed, to trade off performance for space.
 118  */
 119 #ifdef HAVE_FUNC_ATTRIBUTE_PACKED
 120 #define PACKED __attribute__((__packed__))
 121 #else
 122 #define PACKED
 123 #endif
 124
 125 #ifdef __cplusplus
 126 /**
 127  * Macro function that evaluates to true if T is a trivially
 128  * destructible type -- that is, if its (non-virtual) destructor
 129  * performs no action and all member variables and base classes are
 130  * trivially destructible themselves.
 131  */
 132 #   if defined(__GNUC__)
 133 #      if ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)))
 134 #         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
 135 #      endif
 136 #   elif (defined(__clang__) && defined(__has_feature))
 137 #      if __has_feature(has_trivial_destructor)
 138 #         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
 139 #      endif
 140 #   endif
 141 #   ifndef HAS_TRIVIAL_DESTRUCTOR
 142        /* It's always safe (if inefficient) to assume that a
 143         * destructor is non-trivial.
 144         */
 145 #      define HAS_TRIVIAL_DESTRUCTOR(T) (false)
 146 #   endif
 147 #endif
 148
 149 #endif /* UTIL_MACROS_H */