include/urcu/compiler.h

   1 #ifndef _URCU_COMPILER_H
   2 #define _URCU_COMPILER_H
   3
   4 /*
   5  * compiler.h
   6  *
   7  * Compiler definitions.
   8  *
   9  * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * Permission is hereby granted, free of charge, to any person obtaining a copy
  12  * of this software and associated documentation files (the "Software"), to deal
  13  * in the Software without restriction, including without limitation the rights
  14  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  15  * copies of the Software, and to permit persons to whom the Software is
  16  * furnished to do so, subject to the following conditions:
  17  *
  18  * The above copyright notice and this permission notice shall be included in
  19  * all copies or substantial portions of the Software.
  20  */
  21
  22 #include <stddef.h>     /* for offsetof */
  23
  24 #if defined __cplusplus
  25 # include <type_traits> /* for std::remove_cv */
  26 #endif
  27
  28 #define caa_likely(x)   __builtin_expect(!!(x), 1)
  29 #define caa_unlikely(x) __builtin_expect(!!(x), 0)
  30
  31 #define cmm_barrier()   __asm__ __volatile__ ("" : : : "memory")
  32
  33 /*
  34  * Instruct the compiler to perform only a single access to a variable
  35  * (prohibits merging and refetching). The compiler is also forbidden to reorder
  36  * successive instances of CMM_ACCESS_ONCE(), but only when the compiler is aware of
  37  * particular ordering. Compiler ordering can be ensured, for example, by
  38  * putting two CMM_ACCESS_ONCE() in separate C statements.
  39  *
  40  * This macro does absolutely -nothing- to prevent the CPU from reordering,
  41  * merging, or refetching absolutely anything at any time.  Its main intended
  42  * use is to mediate communication between process-level code and irq/NMI
  43  * handlers, all running on the same CPU.
  44  */
  45 #define CMM_ACCESS_ONCE(x)      (*(__volatile__  __typeof__(x) *)&(x))
  46
  47 #ifndef caa_max
  48 #define caa_max(a,b) ((a)>(b)?(a):(b))
  49 #endif
  50
  51 #ifndef caa_min
  52 #define caa_min(a,b) ((a)<(b)?(a):(b))
  53 #endif
  54
  55 #if defined(__SIZEOF_LONG__)
  56 #define CAA_BITS_PER_LONG       (__SIZEOF_LONG__ * 8)
  57 #elif defined(_LP64)
  58 #define CAA_BITS_PER_LONG       64
  59 #else
  60 #define CAA_BITS_PER_LONG       32
  61 #endif
  62
  63 /*
  64  * caa_container_of - Get the address of an object containing a field.
  65  *
  66  * @ptr: pointer to the field.
  67  * @type: type of the object.
  68  * @member: name of the field within the object.
  69  */
  70 #define caa_container_of(ptr, type, member)                             \
  71         __extension__                                                   \
  72         ({                                                              \
  73                 const __typeof__(((type *) NULL)->member) * __ptr = (ptr); \
  74                 (type *)((char *)__ptr - offsetof(type, member));       \
  75         })
  76
  77 /*
  78  * caa_container_of_check_null - Get the address of an object containing a field.
  79  *
  80  * @ptr: pointer to the field.
  81  * @type: type of the object.
  82  * @member: name of the field within the object.
  83  *
  84  * Return the address of the object containing the field. Return NULL if
  85  * @ptr is NULL.
  86  */
  87 #define caa_container_of_check_null(ptr, type, member)                  \
  88         __extension__                                                   \
  89         ({                                                              \
  90                 const __typeof__(((type *) NULL)->member) * __ptr = (ptr); \
  91                 (__ptr) ? (type *)((char *)__ptr - offsetof(type, member)) : NULL; \
  92         })
  93
  94 #define CAA_BUILD_BUG_ON_ZERO(cond) (sizeof(struct { int:-!!(cond); }))
  95 #define CAA_BUILD_BUG_ON(cond) ((void)CAA_BUILD_BUG_ON_ZERO(cond))
  96
  97 /*
  98  * __rcu is an annotation that documents RCU pointer accesses that need
  99  * to be protected by a read-side critical section. Eventually, a static
 100  * checker will be able to use this annotation to detect incorrect RCU
 101  * usage.
 102  */
 103 #define __rcu
 104
 105 #ifdef __cplusplus
 106 #define URCU_FORCE_CAST(_type, arg)     (reinterpret_cast<std::remove_cv<_type>::type>(arg))
 107 #else
 108 #define URCU_FORCE_CAST(type, arg)      ((type) (arg))
 109 #endif
 110
 111 #define caa_is_signed_type(type)        ((type) -1 < (type) 0)
 112
 113 /*
 114  * Cast to unsigned long, sign-extending if @v is signed.
 115  * Note: casting to a larger type or to same type size keeps the sign of
 116  * the expression being cast (see C99 6.3.1.3).
 117  */
 118 #define caa_cast_long_keep_sign(v)      ((unsigned long) (v))
 119
 120 #if defined (__GNUC__) \
 121         && ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 5)    \
 122                 || __GNUC__ >= 5)
 123 #define CDS_DEPRECATED(msg)     \
 124         __attribute__((deprecated(msg)))
 125 #else
 126 #define CDS_DEPRECATED(msg)     \
 127         __attribute__((deprecated))
 128 #endif
 129
 130 #define CAA_ARRAY_SIZE(x)       (sizeof(x) / sizeof((x)[0]))
 131
 132 /*
 133  * URCU_GCC_VERSION is used to blacklist specific GCC versions with known
 134  * bugs, clang also defines these macros to an equivalent GCC version it
 135  * claims to support, so exclude it.
 136  */
 137 #if defined(__GNUC__) && !defined(__clang__)
 138 # define URCU_GCC_VERSION       (__GNUC__ * 10000 \
 139                                 + __GNUC_MINOR__ * 100 \
 140                                 + __GNUC_PATCHLEVEL__)
 141 #endif
 142
 143 #endif /* _URCU_COMPILER_H */