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 #include <assert.h>
  28
  29 /* Compute the size of an array */
  30 #ifndef ARRAY_SIZE
  31 #  define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
  32 #endif
  33
  34 /* For compatibility with Clang's __has_builtin() */
  35 #ifndef __has_builtin
  36 #  define __has_builtin(x) 0
  37 #endif
  38
  39 /**
  40  * __builtin_expect macros
  41  */
  42 #if !defined(HAVE___BUILTIN_EXPECT)
  43 #  define __builtin_expect(x, y) (x)
  44 #endif
  45
  46 #ifndef likely
  47 #  ifdef HAVE___BUILTIN_EXPECT
  48 #    define likely(x)   __builtin_expect(!!(x), 1)
  49 #    define unlikely(x) __builtin_expect(!!(x), 0)
  50 #  else
  51 #    define likely(x)   (x)
  52 #    define unlikely(x) (x)
  53 #  endif
  54 #endif
  55
  56
  57 /**
  58  * Static (compile-time) assertion.
  59  * Basically, use COND to dimension an array.  If COND is false/zero the
  60  * array size will be -1 and we'll get a compilation error.
  61  */
  62 #define STATIC_ASSERT(COND) \
  63    do { \
  64       (void) sizeof(char [1 - 2*!(COND)]); \
  65    } while (0)
  66
  67
  68 /**
  69  * Unreachable macro. Useful for suppressing "control reaches end of non-void
  70  * function" warnings.
  71  */
  72 #ifdef HAVE___BUILTIN_UNREACHABLE
  73 #define unreachable(str)    \
  74 do {                        \
  75    assert(!str);            \
  76    __builtin_unreachable(); \
  77 } while (0)
  78 #elif defined (_MSC_VER)
  79 #define unreachable(str)    \
  80 do {                        \
  81    assert(!str);            \
  82    __assume(0);             \
  83 } while (0)
  84 #else
  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 defined (_MSC_VER)
 103 #define assume(expr) __assume(expr)
 104 #else
 105 #define assume(expr) assert(expr)
 106 #endif
 107
 108 /* Attribute const is used for functions that have no effects other than their
 109  * return value, and only rely on the argument values to compute the return
 110  * value.  As a result, calls to it can be CSEed.  Note that using memory
 111  * pointed to by the arguments is not allowed for const functions.
 112  */
 113 #ifdef HAVE_FUNC_ATTRIBUTE_CONST
 114 #define ATTRIBUTE_CONST __attribute__((__const__))
 115 #else
 116 #define ATTRIBUTE_CONST
 117 #endif
 118
 119 #ifdef HAVE_FUNC_ATTRIBUTE_FLATTEN
 120 #define FLATTEN __attribute__((__flatten__))
 121 #else
 122 #define FLATTEN
 123 #endif
 124
 125 #ifdef HAVE_FUNC_ATTRIBUTE_FORMAT
 126 #define PRINTFLIKE(f, a) __attribute__ ((format(__printf__, f, a)))
 127 #else
 128 #define PRINTFLIKE(f, a)
 129 #endif
 130
 131 #ifdef HAVE_FUNC_ATTRIBUTE_MALLOC
 132 #define MALLOCLIKE __attribute__((__malloc__))
 133 #else
 134 #define MALLOCLIKE
 135 #endif
 136
 137 /* Used to optionally mark structures with misaligned elements or size as
 138  * packed, to trade off performance for space.
 139  */
 140 #ifdef HAVE_FUNC_ATTRIBUTE_PACKED
 141 #define PACKED __attribute__((__packed__))
 142 #else
 143 #define PACKED
 144 #endif
 145
 146 /* Attribute pure is used for functions that have no effects other than their
 147  * return value.  As a result, calls to it can be dead code eliminated.
 148  */
 149 #ifdef HAVE_FUNC_ATTRIBUTE_PURE
 150 #define ATTRIBUTE_PURE __attribute__((__pure__))
 151 #else
 152 #define ATTRIBUTE_PURE
 153 #endif
 154
 155 #ifdef __cplusplus
 156 /**
 157  * Macro function that evaluates to true if T is a trivially
 158  * destructible type -- that is, if its (non-virtual) destructor
 159  * performs no action and all member variables and base classes are
 160  * trivially destructible themselves.
 161  */
 162 #   if defined(__GNUC__)
 163 #      if ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)))
 164 #         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
 165 #      endif
 166 #   elif (defined(__clang__) && defined(__has_feature))
 167 #      if __has_feature(has_trivial_destructor)
 168 #         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
 169 #      endif
 170 #   endif
 171 #   ifndef HAS_TRIVIAL_DESTRUCTOR
 172        /* It's always safe (if inefficient) to assume that a
 173         * destructor is non-trivial.
 174         */
 175 #      define HAS_TRIVIAL_DESTRUCTOR(T) (false)
 176 #   endif
 177 #endif
 178
 179 /**
 180  * PUBLIC/USED macros
 181  *
 182  * If we build the library with gcc's -fvisibility=hidden flag, we'll
 183  * use the PUBLIC macro to mark functions that are to be exported.
 184  *
 185  * We also need to define a USED attribute, so the optimizer doesn't
 186  * inline a static function that we later use in an alias. - ajax
 187  */
 188 #ifndef PUBLIC
 189 #  if defined(__GNUC__) || (defined(__SUNPRO_C) && (__SUNPRO_C >= 0x590))
 190 #    define PUBLIC __attribute__((visibility("default")))
 191 #    define USED __attribute__((used))
 192 #  elif defined(_MSC_VER)
 193 #    define PUBLIC __declspec(dllexport)
 194 #    define USED
 195 #  else
 196 #    define PUBLIC
 197 #    define USED
 198 #  endif
 199 #endif
 200
 201 #ifdef HAVE_FUNC_ATTRIBUTE_UNUSED
 202 #define UNUSED __attribute__((unused))
 203 #else
 204 #define UNUSED
 205 #endif
 206
 207 #ifdef HAVE_FUNC_ATTRIBUTE_WARN_UNUSED_RESULT
 208 #define MUST_CHECK __attribute__((warn_unused_result))
 209 #else
 210 #define MUST_CHECK
 211 #endif
 212
 213 /** Compute ceiling of integer quotient of A divided by B. */
 214 #define DIV_ROUND_UP( A, B )  ( (A) % (B) == 0 ? (A)/(B) : (A)/(B)+1 )
 215
 216 #endif /* UTIL_MACROS_H */