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 /* For compatibility with Clang's __has_builtin() */
  33 #ifndef __has_builtin
  34 #  define __has_builtin(x) 0
  35 #endif
  36
  37 /**
  38  * __builtin_expect macros
  39  */
  40 #if !defined(HAVE___BUILTIN_EXPECT)
  41 #  define __builtin_expect(x, y) (x)
  42 #endif
  43
  44 #ifndef likely
  45 #  ifdef HAVE___BUILTIN_EXPECT
  46 #    define likely(x)   __builtin_expect(!!(x), 1)
  47 #    define unlikely(x) __builtin_expect(!!(x), 0)
  48 #  else
  49 #    define likely(x)   (x)
  50 #    define unlikely(x) (x)
  51 #  endif
  52 #endif
  53
  54
  55 /**
  56  * Static (compile-time) assertion.
  57  * Basically, use COND to dimension an array.  If COND is false/zero the
  58  * array size will be -1 and we'll get a compilation error.
  59  */
  60 #define STATIC_ASSERT(COND) \
  61    do { \
  62       (void) sizeof(char [1 - 2*!(COND)]); \
  63    } while (0)
  64
  65
  66 /**
  67  * Unreachable macro. Useful for suppressing "control reaches end of non-void
  68  * function" warnings.
  69  */
  70 #ifdef HAVE___BUILTIN_UNREACHABLE
  71 #define unreachable(str)    \
  72 do {                        \
  73    assert(!str);            \
  74    __builtin_unreachable(); \
  75 } while (0)
  76 #elif _MSC_VER >= 1200
  77 #define unreachable(str)    \
  78 do {                        \
  79    assert(!str);            \
  80    __assume(0);             \
  81 } while (0)
  82 #endif
  83
  84 #ifndef unreachable
  85 #define unreachable(str) assert(!str)
  86 #endif
  87
  88 /**
  89  * Assume macro. Useful for expressing our assumptions to the compiler,
  90  * typically for purposes of silencing warnings.
  91  */
  92 #if __has_builtin(__builtin_assume)
  93 #define assume(expr)       \
  94 do {                       \
  95    assert(expr);           \
  96    __builtin_assume(expr); \
  97 } while (0)
  98 #elif defined HAVE___BUILTIN_UNREACHABLE
  99 #define assume(expr) ((expr) ? ((void) 0) \
 100                              : (assert(!"assumption failed"), \
 101                                 __builtin_unreachable()))
 102 #elif _MSC_VER >= 1200
 103 #define assume(expr) __assume(expr)
 104 #else
 105 #define assume(expr) assert(expr)
 106 #endif
 107
 108 #ifdef HAVE_FUNC_ATTRIBUTE_FLATTEN
 109 #define FLATTEN __attribute__((__flatten__))
 110 #else
 111 #define FLATTEN
 112 #endif
 113
 114 #ifdef HAVE_FUNC_ATTRIBUTE_FORMAT
 115 #define PRINTFLIKE(f, a) __attribute__ ((format(__printf__, f, a)))
 116 #else
 117 #define PRINTFLIKE(f, a)
 118 #endif
 119
 120 #ifdef HAVE_FUNC_ATTRIBUTE_MALLOC
 121 #define MALLOCLIKE __attribute__((__malloc__))
 122 #else
 123 #define MALLOCLIKE
 124 #endif
 125
 126 /* Used to optionally mark structures with misaligned elements or size as
 127  * packed, to trade off performance for space.
 128  */
 129 #ifdef HAVE_FUNC_ATTRIBUTE_PACKED
 130 #define PACKED __attribute__((__packed__))
 131 #else
 132 #define PACKED
 133 #endif
 134
 135 #ifdef __cplusplus
 136 /**
 137  * Macro function that evaluates to true if T is a trivially
 138  * destructible type -- that is, if its (non-virtual) destructor
 139  * performs no action and all member variables and base classes are
 140  * trivially destructible themselves.
 141  */
 142 #   if defined(__GNUC__)
 143 #      if ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)))
 144 #         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
 145 #      endif
 146 #   elif (defined(__clang__) && defined(__has_feature))
 147 #      if __has_feature(has_trivial_destructor)
 148 #         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
 149 #      endif
 150 #   endif
 151 #   ifndef HAS_TRIVIAL_DESTRUCTOR
 152        /* It's always safe (if inefficient) to assume that a
 153         * destructor is non-trivial.
 154         */
 155 #      define HAS_TRIVIAL_DESTRUCTOR(T) (false)
 156 #   endif
 157 #endif
 158
 159 #endif /* UTIL_MACROS_H */