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 #include "c99_compat.h"
  30
  31 /* Compute the size of an array */
  32 #ifndef ARRAY_SIZE
  33 #  define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
  34 #endif
  35
  36 /* For compatibility with Clang's __has_builtin() */
  37 #ifndef __has_builtin
  38 #  define __has_builtin(x) 0
  39 #endif
  40
  41 /**
  42  * __builtin_expect macros
  43  */
  44 #if !defined(HAVE___BUILTIN_EXPECT)
  45 #  define __builtin_expect(x, y) (x)
  46 #endif
  47
  48 #ifndef likely
  49 #  ifdef HAVE___BUILTIN_EXPECT
  50 #    define likely(x)   __builtin_expect(!!(x), 1)
  51 #    define unlikely(x) __builtin_expect(!!(x), 0)
  52 #  else
  53 #    define likely(x)   (x)
  54 #    define unlikely(x) (x)
  55 #  endif
  56 #endif
  57
  58
  59 /**
  60  * Static (compile-time) assertion.
  61  * Basically, use COND to dimension an array.  If COND is false/zero the
  62  * array size will be -1 and we'll get a compilation error.
  63  */
  64 #define STATIC_ASSERT(COND) \
  65    do { \
  66       (void) sizeof(char [1 - 2*!(COND)]); \
  67    } while (0)
  68
  69
  70 /**
  71  * Unreachable macro. Useful for suppressing "control reaches end of non-void
  72  * function" warnings.
  73  */
  74 #ifdef HAVE___BUILTIN_UNREACHABLE
  75 #define unreachable(str)    \
  76 do {                        \
  77    assert(!str);            \
  78    __builtin_unreachable(); \
  79 } while (0)
  80 #elif defined (_MSC_VER)
  81 #define unreachable(str)    \
  82 do {                        \
  83    assert(!str);            \
  84    __assume(0);             \
  85 } while (0)
  86 #else
  87 #define unreachable(str) assert(!str)
  88 #endif
  89
  90 /**
  91  * Assume macro. Useful for expressing our assumptions to the compiler,
  92  * typically for purposes of silencing warnings.
  93  */
  94 #if __has_builtin(__builtin_assume)
  95 #define assume(expr)       \
  96 do {                       \
  97    assert(expr);           \
  98    __builtin_assume(expr); \
  99 } while (0)
 100 #elif defined HAVE___BUILTIN_UNREACHABLE
 101 #define assume(expr) ((expr) ? ((void) 0) \
 102                              : (assert(!"assumption failed"), \
 103                                 __builtin_unreachable()))
 104 #elif defined (_MSC_VER)
 105 #define assume(expr) __assume(expr)
 106 #else
 107 #define assume(expr) assert(expr)
 108 #endif
 109
 110 /* Attribute const is used for functions that have no effects other than their
 111  * return value, and only rely on the argument values to compute the return
 112  * value.  As a result, calls to it can be CSEed.  Note that using memory
 113  * pointed to by the arguments is not allowed for const functions.
 114  */
 115 #ifdef HAVE_FUNC_ATTRIBUTE_CONST
 116 #define ATTRIBUTE_CONST __attribute__((__const__))
 117 #else
 118 #define ATTRIBUTE_CONST
 119 #endif
 120
 121 #ifdef HAVE_FUNC_ATTRIBUTE_FLATTEN
 122 #define FLATTEN __attribute__((__flatten__))
 123 #else
 124 #define FLATTEN
 125 #endif
 126
 127 #ifdef HAVE_FUNC_ATTRIBUTE_FORMAT
 128 #define PRINTFLIKE(f, a) __attribute__ ((format(__printf__, f, a)))
 129 #else
 130 #define PRINTFLIKE(f, a)
 131 #endif
 132
 133 #ifdef HAVE_FUNC_ATTRIBUTE_MALLOC
 134 #define MALLOCLIKE __attribute__((__malloc__))
 135 #else
 136 #define MALLOCLIKE
 137 #endif
 138
 139 /* Used to optionally mark structures with misaligned elements or size as
 140  * packed, to trade off performance for space.
 141  */
 142 #ifdef HAVE_FUNC_ATTRIBUTE_PACKED
 143 #define PACKED __attribute__((__packed__))
 144 #else
 145 #define PACKED
 146 #endif
 147
 148 /* Attribute pure is used for functions that have no effects other than their
 149  * return value.  As a result, calls to it can be dead code eliminated.
 150  */
 151 #ifdef HAVE_FUNC_ATTRIBUTE_PURE
 152 #define ATTRIBUTE_PURE __attribute__((__pure__))
 153 #else
 154 #define ATTRIBUTE_PURE
 155 #endif
 156
 157 #ifdef __cplusplus
 158 /**
 159  * Macro function that evaluates to true if T is a trivially
 160  * destructible type -- that is, if its (non-virtual) destructor
 161  * performs no action and all member variables and base classes are
 162  * trivially destructible themselves.
 163  */
 164 #   if defined(__GNUC__)
 165 #      if ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)))
 166 #         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
 167 #      endif
 168 #   elif (defined(__clang__) && defined(__has_feature))
 169 #      if __has_feature(has_trivial_destructor)
 170 #         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
 171 #      endif
 172 #   endif
 173 #   ifndef HAS_TRIVIAL_DESTRUCTOR
 174        /* It's always safe (if inefficient) to assume that a
 175         * destructor is non-trivial.
 176         */
 177 #      define HAS_TRIVIAL_DESTRUCTOR(T) (false)
 178 #   endif
 179 #endif
 180
 181 /**
 182  * PUBLIC/USED macros
 183  *
 184  * If we build the library with gcc's -fvisibility=hidden flag, we'll
 185  * use the PUBLIC macro to mark functions that are to be exported.
 186  *
 187  * We also need to define a USED attribute, so the optimizer doesn't
 188  * inline a static function that we later use in an alias. - ajax
 189  */
 190 #ifndef PUBLIC
 191 #  if defined(__GNUC__)
 192 #    define PUBLIC __attribute__((visibility("default")))
 193 #    define USED __attribute__((used))
 194 #  elif defined(_MSC_VER)
 195 #    define PUBLIC __declspec(dllexport)
 196 #    define USED
 197 #  else
 198 #    define PUBLIC
 199 #    define USED
 200 #  endif
 201 #endif
 202
 203 #ifdef HAVE_FUNC_ATTRIBUTE_UNUSED
 204 #define UNUSED __attribute__((unused))
 205 #else
 206 #define UNUSED
 207 #endif
 208
 209 #define MAYBE_UNUSED UNUSED
 210
 211 #ifdef HAVE_FUNC_ATTRIBUTE_WARN_UNUSED_RESULT
 212 #define MUST_CHECK __attribute__((warn_unused_result))
 213 #else
 214 #define MUST_CHECK
 215 #endif
 216
 217 /** Compute ceiling of integer quotient of A divided by B. */
 218 #define DIV_ROUND_UP( A, B )  ( (A) % (B) == 0 ? (A)/(B) : (A)/(B)+1 )
 219
 220 #endif /* UTIL_MACROS_H */