macros.h revision af69d88d 
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(__GNUC__)
37#  define __builtin_expect(x, y) (x)
38#endif
39
40#ifndef likely
41#  ifdef __GNUC__
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#if __GNUC__ >= 4 && __GNUC_MINOR__ >= 5
67#define unreachable(str)    \
68do {                        \
69   assert(!str);            \
70   __builtin_unreachable(); \
71} while (0)
72#elif (defined(__clang__) && defined(__has_builtin))
73# if __has_builtin(__builtin_unreachable)
74#  define unreachable(str)  \
75do {                        \
76   assert(!str);            \
77   __builtin_unreachable(); \
78} while (0)
79# endif
80#endif
81
82#ifndef unreachable
83#define unreachable(str)
84#endif
85
86
87#if (__GNUC__ >= 3)
88#define PRINTFLIKE(f, a) __attribute__ ((format(__printf__, f, a)))
89#else
90#define PRINTFLIKE(f, a)
91#endif
92
93
94/* Used to optionally mark structures with misaligned elements or size as
95 * packed, to trade off performance for space.
96 */
97#if (__GNUC__ >= 3)
98#define PACKED __attribute__((__packed__))
99#else
100#define PACKED
101#endif
102
103
104#ifdef __cplusplus
105/**
106 * Macro function that evaluates to true if T is a trivially
107 * destructible type -- that is, if its (non-virtual) destructor
108 * performs no action and all member variables and base classes are
109 * trivially destructible themselves.
110 */
111#   if defined(__GNUC__)
112#      if ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 3)))
113#         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
114#      endif
115#   elif (defined(__clang__) && defined(__has_feature))
116#      if __has_feature(has_trivial_destructor)
117#         define HAS_TRIVIAL_DESTRUCTOR(T) __has_trivial_destructor(T)
118#      endif
119#   endif
120#   ifndef HAS_TRIVIAL_DESTRUCTOR
121       /* It's always safe (if inefficient) to assume that a
122        * destructor is non-trivial.
123        */
124#      define HAS_TRIVIAL_DESTRUCTOR(T) (false)
125#   endif
126#endif
127
128#endif /* UTIL_MACROS_H */
129