urcu/arch/generic: Use atomic builtins if configured
[urcu.git] / include / urcu / compiler.h
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1// SPDX-FileCopyrightText: 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
2//
3// SPDX-License-Identifier: LGPL-2.1-or-later
4
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5#ifndef _URCU_COMPILER_H
6#define _URCU_COMPILER_H
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7
8/*
af02d47e 9 * Compiler definitions.
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10 */
11
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12#include <stddef.h> /* for offsetof */
13
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14#if defined __cplusplus
15# include <type_traits> /* for std::remove_cv */
16#endif
17
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18#include <urcu/config.h>
19
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20#define caa_likely(x) __builtin_expect(!!(x), 1)
21#define caa_unlikely(x) __builtin_expect(!!(x), 0)
2dc5fa0f 22
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23#ifdef CONFIG_RCU_USE_ATOMIC_BUILTINS
24# define cmm_barrier() __atomic_signal_fence(__ATOMIC_SEQ_CST)
25#else
26# define cmm_barrier() __asm__ __volatile__ ("" : : : "memory")
27#endif
2dc5fa0f 28
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29/*
30 * Instruct the compiler to perform only a single access to a variable
31 * (prohibits merging and refetching). The compiler is also forbidden to reorder
6cf3827c 32 * successive instances of CMM_ACCESS_ONCE(), but only when the compiler is aware of
af02d47e 33 * particular ordering. Compiler ordering can be ensured, for example, by
6cf3827c 34 * putting two CMM_ACCESS_ONCE() in separate C statements.
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35 *
36 * This macro does absolutely -nothing- to prevent the CPU from reordering,
37 * merging, or refetching absolutely anything at any time. Its main intended
38 * use is to mediate communication between process-level code and irq/NMI
39 * handlers, all running on the same CPU.
40 */
e51500ed 41#define CMM_ACCESS_ONCE(x) (*(__volatile__ __typeof__(x) *)&(x))
af02d47e 42
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43#ifndef caa_max
44#define caa_max(a,b) ((a)>(b)?(a):(b))
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45#endif
46
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47#ifndef caa_min
48#define caa_min(a,b) ((a)<(b)?(a):(b))
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49#endif
50
1b27a772 51#if defined(__SIZEOF_LONG__)
06f22bdb 52#define CAA_BITS_PER_LONG (__SIZEOF_LONG__ * 8)
1b27a772 53#elif defined(_LP64)
06f22bdb 54#define CAA_BITS_PER_LONG 64
1b27a772 55#else
06f22bdb 56#define CAA_BITS_PER_LONG 32
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57#endif
58
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59/*
60 * caa_container_of - Get the address of an object containing a field.
61 *
62 * @ptr: pointer to the field.
63 * @type: type of the object.
64 * @member: name of the field within the object.
65 */
66#define caa_container_of(ptr, type, member) \
1b85da85 67 __extension__ \
453629a9 68 ({ \
bdffa73a 69 const __typeof__(((type *) NULL)->member) * __ptr = (ptr); \
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70 (type *)((char *)__ptr - offsetof(type, member)); \
71 })
72
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73/*
74 * caa_container_of_check_null - Get the address of an object containing a field.
75 *
76 * @ptr: pointer to the field.
77 * @type: type of the object.
78 * @member: name of the field within the object.
79 *
80 * Return the address of the object containing the field. Return NULL if
81 * @ptr is NULL.
82 */
83#define caa_container_of_check_null(ptr, type, member) \
84 __extension__ \
85 ({ \
86 const __typeof__(((type *) NULL)->member) * __ptr = (ptr); \
87 (__ptr) ? (type *)((char *)__ptr - offsetof(type, member)) : NULL; \
88 })
89
78bec10c 90#define CAA_BUILD_BUG_ON_ZERO(cond) (sizeof(struct { int:-!!(cond); }))
9f59b220 91#define CAA_BUILD_BUG_ON(cond) ((void)CAA_BUILD_BUG_ON_ZERO(cond))
78bec10c 92
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93/*
94 * __rcu is an annotation that documents RCU pointer accesses that need
95 * to be protected by a read-side critical section. Eventually, a static
96 * checker will be able to use this annotation to detect incorrect RCU
97 * usage.
98 */
99#define __rcu
100
4501f284 101#ifdef __cplusplus
06326a94 102#define URCU_FORCE_CAST(_type, arg) (reinterpret_cast<std::remove_cv<_type>::type>(arg))
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103#else
104#define URCU_FORCE_CAST(type, arg) ((type) (arg))
105#endif
106
4b5f005b 107#define caa_is_signed_type(type) ((type) -1 < (type) 0)
e56d99bf 108
4b5f005b 109/*
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110 * Cast to unsigned long, sign-extending if @v is signed.
111 * Note: casting to a larger type or to same type size keeps the sign of
112 * the expression being cast (see C99 6.3.1.3).
4b5f005b 113 */
e4749953 114#define caa_cast_long_keep_sign(v) ((unsigned long) (v))
e56d99bf 115
706d1165 116#if defined (__GNUC__) \
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117 && ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 5) \
118 || __GNUC__ >= 5)
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119#define CDS_DEPRECATED(msg) \
120 __attribute__((deprecated(msg)))
121#else
122#define CDS_DEPRECATED(msg) \
123 __attribute__((deprecated))
124#endif
125
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126#define CAA_ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
127
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128/*
129 * URCU_GCC_VERSION is used to blacklist specific GCC versions with known
130 * bugs, clang also defines these macros to an equivalent GCC version it
131 * claims to support, so exclude it.
132 */
133#if defined(__GNUC__) && !defined(__clang__)
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134# define URCU_GCC_VERSION (__GNUC__ * 10000 \
135 + __GNUC_MINOR__ * 100 \
136 + __GNUC_PATCHLEVEL__)
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137#endif
138
ec4e58a3 139#endif /* _URCU_COMPILER_H */
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