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 <math.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 _MSC_VER >= 1200
  79 #define unreachable(str)    \
  80 do {                        \
  81    assert(!str);            \
  82    __assume(0);             \
  83 } while (0)
  84 #endif
  85
  86 #ifndef unreachable
  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 _MSC_VER >= 1200
 105 #define assume(expr) __assume(expr)
 106 #else
 107 #define assume(expr) assert(expr)
 108 #endif
 109
 110 #ifdef HAVE_FUNC_ATTRIBUTE_FLATTEN
 111 #define FLATTEN __attribute__((__flatten__))
 112 #else
 113 #define FLATTEN
 114 #endif
 115
 116 #ifdef HAVE_FUNC_ATTRIBUTE_FORMAT
 117 #define PRINTFLIKE(f, a) __attribute__ ((format(__printf__, f, a)))
 118 #else
 119 #define PRINTFLIKE(f, a)
 120 #endif
 121
 122 #ifdef HAVE_FUNC_ATTRIBUTE_MALLOC
 123 #define MALLOCLIKE __attribute__((__malloc__))
 124 #else
 125 #define MALLOCLIKE
 126 #endif
 127
 128 /* Used to optionally mark structures with misaligned elements or size as
 129  * packed, to trade off performance for space.
 130  */
 131 #ifdef HAVE_FUNC_ATTRIBUTE_PACKED
 132 #define PACKED __attribute__((__packed__))
 133 #else
 134 #define PACKED
 135 #endif
 136
 137 #ifdef __cplusplus
 138 /**
 139  * Macro function that evaluates to true if T is a trivially
 140  * destructible type -- that is, if its (non-virtual) destructor
 141  * performs no action and all member variables and base classes are
 142  * trivially destructible themselves.
 143  */
 144 #   if defined(__GNUC__)
 145 #      if ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)))
 146 #         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
 147 #      endif
 148 #   elif (defined(__clang__) && defined(__has_feature))
 149 #      if __has_feature(has_trivial_destructor)
 150 #         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
 151 #      endif
 152 #   endif
 153 #   ifndef HAS_TRIVIAL_DESTRUCTOR
 154        /* It's always safe (if inefficient) to assume that a
 155         * destructor is non-trivial.
 156         */
 157 #      define HAS_TRIVIAL_DESTRUCTOR(T) (false)
 158 #   endif
 159 #endif
 160
 161 /* The fallbacks below don't work correctly in C++ and properly detecting
 162  * FP_NORMAL in C++ is hard.  Since we don't use fpclassify in any C++ code
 163  * at the moment, we can just predicate this whole thing by not being in
 164  * C++ and we shoudld be ok.  If we ever want to use fpclassify in a C++
 165  * file, we will have to revisit this.
 166  */
 167 #ifndef __cplusplus
 168
 169 #ifdef FP_NORMAL
 170 /* ISO C99 says that fpclassify is a macro.  Assume that any implementation
 171  * of fpclassify, whether it's in a C99 compiler or not, will be a macro.
 172  */
 173 #elif defined(_MSC_VER)
 174 /* Not required on VS2013 and above. */
 175 /* Oddly, the fpclassify() function doesn't exist in such a form
 176  * on MSVC.  This is an implementation using slightly different
 177  * lower-level Windows functions.
 178  */
 179 #include <float.h>
 180
 181 static inline enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}
 182 fpclassify(double x)
 183 {
 184     switch(_fpclass(x)) {
 185         case _FPCLASS_SNAN: /* signaling NaN */
 186         case _FPCLASS_QNAN: /* quiet NaN */
 187             return FP_NAN;
 188         case _FPCLASS_NINF: /* negative infinity */
 189         case _FPCLASS_PINF: /* positive infinity */
 190             return FP_INFINITE;
 191         case _FPCLASS_NN:   /* negative normal */
 192         case _FPCLASS_PN:   /* positive normal */
 193             return FP_NORMAL;
 194         case _FPCLASS_ND:   /* negative denormalized */
 195         case _FPCLASS_PD:   /* positive denormalized */
 196             return FP_SUBNORMAL;
 197         case _FPCLASS_NZ:   /* negative zero */
 198         case _FPCLASS_PZ:   /* positive zero */
 199             return FP_ZERO;
 200         default:
 201             /* Should never get here; but if we do, this will guarantee
 202              * that the pattern is not treated like a number.
 203              */
 204             return FP_NAN;
 205     }
 206 }
 207
 208 #else
 209
 210 static inline enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}
 211 fpclassify(double x)
 212 {
 213    /* XXX do something better someday */
 214    return FP_NORMAL;
 215 }
 216
 217 #endif
 218
 219 #endif /* __cplusplus */
 220
 221 #endif /* UTIL_MACROS_H */