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12d2dd7060
This patch optimizes the generic spinlock code. The type pthread_spinlock_t is a typedef to volatile int on all archs. Passing a volatile pointer to the atomic macros which are not mapped to the C11 atomic builtins can lead to extra stores and loads to stack if such a macro creates a temporary variable by using "__typeof (*(mem)) tmp;". Thus, those macros which are used by spinlock code - atomic_exchange_acquire, atomic_load_relaxed, atomic_compare_exchange_weak - have to be adjusted. According to the comment from Szabolcs Nagy, the type of a cast expression is unqualified (see http://www.open-std.org/jtc1/sc22/wg14/www/docs/dr_423.htm): __typeof ((__typeof (*(mem)) *(mem)) tmp; Thus from spinlock perspective the variable tmp is of type int instead of type volatile int. This patch adjusts those macros in include/atomic.h. With this construct GCC >= 5 omits the extra stores and loads. The atomic macros are replaced by the C11 like atomic macros and thus the code is aligned to it. The pthread_spin_unlock implementation is now using release memory order instead of sequentially consistent memory order. The issue with passed volatile int pointers applies to the C11 like atomic macros as well as the ones used before. I've added a glibc_likely hint to the first atomic exchange in pthread_spin_lock in order to return immediately to the caller if the lock is free. Without the hint, there is an additional jump if the lock is free. I've added the atomic_spin_nop macro within the loop of plain reads. The plain reads are also realized by C11 like atomic_load_relaxed macro. The new define ATOMIC_EXCHANGE_USES_CAS determines if the first try to acquire the spinlock in pthread_spin_lock or pthread_spin_trylock is an exchange or a CAS. This is defined in atomic-machine.h for all architectures. The define SPIN_LOCK_READS_BETWEEN_CMPXCHG is now removed. There is no technical reason for throwing in a CAS every now and then, and so far we have no evidence that it can improve performance. If that would be the case, we have to adjust other spin-waiting loops elsewhere, too! Using a CAS loop without plain reads is not a good idea on many targets and wasn't used by one. Thus there is now no option to do so. Architectures are now using the generic spinlock automatically if they do not provide an own implementation. Thus the pthread_spin_lock.c files in sysdeps folder are deleted. ChangeLog: * NEWS: Mention new spinlock implementation. * include/atomic.h: (__atomic_val_bysize): Cast type to omit volatile qualifier. (atomic_exchange_acq): Likewise. (atomic_load_relaxed): Likewise. (ATOMIC_EXCHANGE_USES_CAS): Check definition. * nptl/pthread_spin_init.c (pthread_spin_init): Use atomic_store_relaxed. * nptl/pthread_spin_lock.c (pthread_spin_lock): Use C11-like atomic macros. * nptl/pthread_spin_trylock.c (pthread_spin_trylock): Likewise. * nptl/pthread_spin_unlock.c (pthread_spin_unlock): Use atomic_store_release. * sysdeps/aarch64/nptl/pthread_spin_lock.c: Delete File. * sysdeps/arm/nptl/pthread_spin_lock.c: Likewise. * sysdeps/hppa/nptl/pthread_spin_lock.c: Likewise. * sysdeps/m68k/nptl/pthread_spin_lock.c: Likewise. * sysdeps/microblaze/nptl/pthread_spin_lock.c: Likewise. * sysdeps/mips/nptl/pthread_spin_lock.c: Likewise. * sysdeps/nios2/nptl/pthread_spin_lock.c: Likewise. * sysdeps/aarch64/atomic-machine.h (ATOMIC_EXCHANGE_USES_CAS): Define. * sysdeps/alpha/atomic-machine.h: Likewise. * sysdeps/arm/atomic-machine.h: Likewise. * sysdeps/i386/atomic-machine.h: Likewise. * sysdeps/ia64/atomic-machine.h: Likewise. * sysdeps/m68k/coldfire/atomic-machine.h: Likewise. * sysdeps/m68k/m680x0/m68020/atomic-machine.h: Likewise. * sysdeps/microblaze/atomic-machine.h: Likewise. * sysdeps/mips/atomic-machine.h: Likewise. * sysdeps/powerpc/powerpc32/atomic-machine.h: Likewise. * sysdeps/powerpc/powerpc64/atomic-machine.h: Likewise. * sysdeps/s390/atomic-machine.h: Likewise. * sysdeps/sparc/sparc32/atomic-machine.h: Likewise. * sysdeps/sparc/sparc32/sparcv9/atomic-machine.h: Likewise. * sysdeps/sparc/sparc64/atomic-machine.h: Likewise. * sysdeps/tile/tilegx/atomic-machine.h: Likewise. * sysdeps/tile/tilepro/atomic-machine.h: Likewise. * sysdeps/unix/sysv/linux/hppa/atomic-machine.h: Likewise. * sysdeps/unix/sysv/linux/m68k/coldfire/atomic-machine.h: Likewise. * sysdeps/unix/sysv/linux/nios2/atomic-machine.h: Likewise. * sysdeps/unix/sysv/linux/sh/atomic-machine.h: Likewise. * sysdeps/x86_64/atomic-machine.h: Likewise.
830 lines
29 KiB
C
830 lines
29 KiB
C
/* Internal macros for atomic operations for GNU C Library.
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Copyright (C) 2002-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _ATOMIC_H
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#define _ATOMIC_H 1
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/* This header defines three types of macros:
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- atomic arithmetic and logic operation on memory. They all
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have the prefix "atomic_".
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- conditionally atomic operations of the same kinds. These
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always behave identical but can be faster when atomicity
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is not really needed since only one thread has access to
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the memory location. In that case the code is slower in
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the multi-thread case. The interfaces have the prefix
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"catomic_".
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- support functions like barriers. They also have the prefix
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"atomic_".
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Architectures must provide a few lowlevel macros (the compare
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and exchange definitions). All others are optional. They
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should only be provided if the architecture has specific
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support for the operation.
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As <atomic.h> macros are usually heavily nested and often use local
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variables to make sure side-effects are evaluated properly, use for
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macro local variables a per-macro unique prefix. This file uses
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__atgN_ prefix where N is different in each macro. */
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#include <stdlib.h>
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#include <atomic-machine.h>
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/* Wrapper macros to call pre_NN_post (mem, ...) where NN is the
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bit width of *MEM. The calling macro puts parens around MEM
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and following args. */
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#define __atomic_val_bysize(pre, post, mem, ...) \
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({ \
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__typeof ((__typeof (*(mem))) *(mem)) __atg1_result; \
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if (sizeof (*mem) == 1) \
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__atg1_result = pre##_8_##post (mem, __VA_ARGS__); \
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else if (sizeof (*mem) == 2) \
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__atg1_result = pre##_16_##post (mem, __VA_ARGS__); \
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else if (sizeof (*mem) == 4) \
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__atg1_result = pre##_32_##post (mem, __VA_ARGS__); \
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else if (sizeof (*mem) == 8) \
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__atg1_result = pre##_64_##post (mem, __VA_ARGS__); \
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else \
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abort (); \
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__atg1_result; \
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})
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#define __atomic_bool_bysize(pre, post, mem, ...) \
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({ \
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int __atg2_result; \
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if (sizeof (*mem) == 1) \
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__atg2_result = pre##_8_##post (mem, __VA_ARGS__); \
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else if (sizeof (*mem) == 2) \
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__atg2_result = pre##_16_##post (mem, __VA_ARGS__); \
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else if (sizeof (*mem) == 4) \
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__atg2_result = pre##_32_##post (mem, __VA_ARGS__); \
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else if (sizeof (*mem) == 8) \
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__atg2_result = pre##_64_##post (mem, __VA_ARGS__); \
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else \
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abort (); \
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__atg2_result; \
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})
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/* Atomically store NEWVAL in *MEM if *MEM is equal to OLDVAL.
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Return the old *MEM value. */
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#if !defined atomic_compare_and_exchange_val_acq \
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&& defined __arch_compare_and_exchange_val_32_acq
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# define atomic_compare_and_exchange_val_acq(mem, newval, oldval) \
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__atomic_val_bysize (__arch_compare_and_exchange_val,acq, \
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mem, newval, oldval)
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#endif
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#ifndef catomic_compare_and_exchange_val_acq
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# ifdef __arch_c_compare_and_exchange_val_32_acq
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# define catomic_compare_and_exchange_val_acq(mem, newval, oldval) \
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__atomic_val_bysize (__arch_c_compare_and_exchange_val,acq, \
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mem, newval, oldval)
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# else
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# define catomic_compare_and_exchange_val_acq(mem, newval, oldval) \
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atomic_compare_and_exchange_val_acq (mem, newval, oldval)
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# endif
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#endif
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#ifndef catomic_compare_and_exchange_val_rel
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# ifndef atomic_compare_and_exchange_val_rel
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# define catomic_compare_and_exchange_val_rel(mem, newval, oldval) \
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catomic_compare_and_exchange_val_acq (mem, newval, oldval)
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# else
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# define catomic_compare_and_exchange_val_rel(mem, newval, oldval) \
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atomic_compare_and_exchange_val_rel (mem, newval, oldval)
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# endif
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#endif
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#ifndef atomic_compare_and_exchange_val_rel
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# define atomic_compare_and_exchange_val_rel(mem, newval, oldval) \
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atomic_compare_and_exchange_val_acq (mem, newval, oldval)
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#endif
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/* Atomically store NEWVAL in *MEM if *MEM is equal to OLDVAL.
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Return zero if *MEM was changed or non-zero if no exchange happened. */
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#ifndef atomic_compare_and_exchange_bool_acq
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# ifdef __arch_compare_and_exchange_bool_32_acq
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# define atomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
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__atomic_bool_bysize (__arch_compare_and_exchange_bool,acq, \
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mem, newval, oldval)
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# else
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# define atomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
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({ /* Cannot use __oldval here, because macros later in this file might \
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call this macro with __oldval argument. */ \
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__typeof (oldval) __atg3_old = (oldval); \
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atomic_compare_and_exchange_val_acq (mem, newval, __atg3_old) \
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!= __atg3_old; \
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})
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# endif
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#endif
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#ifndef catomic_compare_and_exchange_bool_acq
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# ifdef __arch_c_compare_and_exchange_bool_32_acq
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# define catomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
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__atomic_bool_bysize (__arch_c_compare_and_exchange_bool,acq, \
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mem, newval, oldval)
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# else
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# define catomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
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({ /* Cannot use __oldval here, because macros later in this file might \
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call this macro with __oldval argument. */ \
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__typeof (oldval) __atg4_old = (oldval); \
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catomic_compare_and_exchange_val_acq (mem, newval, __atg4_old) \
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!= __atg4_old; \
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})
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# endif
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#endif
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/* Store NEWVALUE in *MEM and return the old value. */
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#ifndef atomic_exchange_acq
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# define atomic_exchange_acq(mem, newvalue) \
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({ __typeof ((__typeof (*(mem))) *(mem)) __atg5_oldval; \
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__typeof (mem) __atg5_memp = (mem); \
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__typeof ((__typeof (*(mem))) *(mem)) __atg5_value = (newvalue); \
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\
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do \
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__atg5_oldval = *__atg5_memp; \
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while (__builtin_expect \
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(atomic_compare_and_exchange_bool_acq (__atg5_memp, __atg5_value, \
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__atg5_oldval), 0)); \
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\
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__atg5_oldval; })
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#endif
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#ifndef atomic_exchange_rel
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# define atomic_exchange_rel(mem, newvalue) atomic_exchange_acq (mem, newvalue)
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#endif
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/* Add VALUE to *MEM and return the old value of *MEM. */
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#ifndef atomic_exchange_and_add_acq
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# ifdef atomic_exchange_and_add
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# define atomic_exchange_and_add_acq(mem, value) \
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atomic_exchange_and_add (mem, value)
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# else
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# define atomic_exchange_and_add_acq(mem, value) \
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({ __typeof (*(mem)) __atg6_oldval; \
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__typeof (mem) __atg6_memp = (mem); \
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__typeof (*(mem)) __atg6_value = (value); \
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\
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do \
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__atg6_oldval = *__atg6_memp; \
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while (__builtin_expect \
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(atomic_compare_and_exchange_bool_acq (__atg6_memp, \
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__atg6_oldval \
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+ __atg6_value, \
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__atg6_oldval), 0)); \
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\
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__atg6_oldval; })
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# endif
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#endif
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#ifndef atomic_exchange_and_add_rel
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# define atomic_exchange_and_add_rel(mem, value) \
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atomic_exchange_and_add_acq(mem, value)
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#endif
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#ifndef atomic_exchange_and_add
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# define atomic_exchange_and_add(mem, value) \
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atomic_exchange_and_add_acq(mem, value)
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#endif
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#ifndef catomic_exchange_and_add
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# define catomic_exchange_and_add(mem, value) \
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({ __typeof (*(mem)) __atg7_oldv; \
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__typeof (mem) __atg7_memp = (mem); \
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__typeof (*(mem)) __atg7_value = (value); \
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\
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do \
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__atg7_oldv = *__atg7_memp; \
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while (__builtin_expect \
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(catomic_compare_and_exchange_bool_acq (__atg7_memp, \
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__atg7_oldv \
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+ __atg7_value, \
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__atg7_oldv), 0)); \
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\
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__atg7_oldv; })
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#endif
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#ifndef atomic_max
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# define atomic_max(mem, value) \
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do { \
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__typeof (*(mem)) __atg8_oldval; \
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__typeof (mem) __atg8_memp = (mem); \
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__typeof (*(mem)) __atg8_value = (value); \
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do { \
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__atg8_oldval = *__atg8_memp; \
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if (__atg8_oldval >= __atg8_value) \
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break; \
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} while (__builtin_expect \
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(atomic_compare_and_exchange_bool_acq (__atg8_memp, __atg8_value,\
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__atg8_oldval), 0)); \
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} while (0)
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#endif
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#ifndef catomic_max
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# define catomic_max(mem, value) \
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do { \
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__typeof (*(mem)) __atg9_oldv; \
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__typeof (mem) __atg9_memp = (mem); \
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__typeof (*(mem)) __atg9_value = (value); \
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do { \
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__atg9_oldv = *__atg9_memp; \
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if (__atg9_oldv >= __atg9_value) \
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break; \
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} while (__builtin_expect \
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(catomic_compare_and_exchange_bool_acq (__atg9_memp, \
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__atg9_value, \
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__atg9_oldv), 0)); \
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} while (0)
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#endif
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#ifndef atomic_min
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# define atomic_min(mem, value) \
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do { \
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__typeof (*(mem)) __atg10_oldval; \
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__typeof (mem) __atg10_memp = (mem); \
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__typeof (*(mem)) __atg10_value = (value); \
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do { \
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__atg10_oldval = *__atg10_memp; \
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if (__atg10_oldval <= __atg10_value) \
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break; \
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} while (__builtin_expect \
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(atomic_compare_and_exchange_bool_acq (__atg10_memp, \
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__atg10_value, \
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__atg10_oldval), 0)); \
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} while (0)
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#endif
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#ifndef atomic_add
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# define atomic_add(mem, value) (void) atomic_exchange_and_add ((mem), (value))
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#endif
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#ifndef catomic_add
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# define catomic_add(mem, value) \
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(void) catomic_exchange_and_add ((mem), (value))
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#endif
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#ifndef atomic_increment
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# define atomic_increment(mem) atomic_add ((mem), 1)
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#endif
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#ifndef catomic_increment
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# define catomic_increment(mem) catomic_add ((mem), 1)
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#endif
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#ifndef atomic_increment_val
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# define atomic_increment_val(mem) (atomic_exchange_and_add ((mem), 1) + 1)
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#endif
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#ifndef catomic_increment_val
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# define catomic_increment_val(mem) (catomic_exchange_and_add ((mem), 1) + 1)
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#endif
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/* Add one to *MEM and return true iff it's now zero. */
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#ifndef atomic_increment_and_test
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# define atomic_increment_and_test(mem) \
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(atomic_exchange_and_add ((mem), 1) + 1 == 0)
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#endif
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#ifndef atomic_decrement
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# define atomic_decrement(mem) atomic_add ((mem), -1)
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#endif
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#ifndef catomic_decrement
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# define catomic_decrement(mem) catomic_add ((mem), -1)
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#endif
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#ifndef atomic_decrement_val
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# define atomic_decrement_val(mem) (atomic_exchange_and_add ((mem), -1) - 1)
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#endif
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#ifndef catomic_decrement_val
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# define catomic_decrement_val(mem) (catomic_exchange_and_add ((mem), -1) - 1)
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#endif
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/* Subtract 1 from *MEM and return true iff it's now zero. */
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#ifndef atomic_decrement_and_test
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# define atomic_decrement_and_test(mem) \
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(atomic_exchange_and_add ((mem), -1) == 1)
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#endif
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/* Decrement *MEM if it is > 0, and return the old value. */
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#ifndef atomic_decrement_if_positive
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# define atomic_decrement_if_positive(mem) \
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({ __typeof (*(mem)) __atg11_oldval; \
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__typeof (mem) __atg11_memp = (mem); \
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\
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do \
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{ \
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__atg11_oldval = *__atg11_memp; \
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if (__glibc_unlikely (__atg11_oldval <= 0)) \
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break; \
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} \
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while (__builtin_expect \
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(atomic_compare_and_exchange_bool_acq (__atg11_memp, \
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__atg11_oldval - 1, \
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__atg11_oldval), 0)); \
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__atg11_oldval; })
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#endif
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#ifndef atomic_add_negative
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# define atomic_add_negative(mem, value) \
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({ __typeof (value) __atg12_value = (value); \
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atomic_exchange_and_add (mem, __atg12_value) < -__atg12_value; })
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#endif
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#ifndef atomic_add_zero
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# define atomic_add_zero(mem, value) \
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({ __typeof (value) __atg13_value = (value); \
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atomic_exchange_and_add (mem, __atg13_value) == -__atg13_value; })
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#endif
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#ifndef atomic_bit_set
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# define atomic_bit_set(mem, bit) \
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(void) atomic_bit_test_set(mem, bit)
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#endif
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#ifndef atomic_bit_test_set
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# define atomic_bit_test_set(mem, bit) \
|
|
({ __typeof (*(mem)) __atg14_old; \
|
|
__typeof (mem) __atg14_memp = (mem); \
|
|
__typeof (*(mem)) __atg14_mask = ((__typeof (*(mem))) 1 << (bit)); \
|
|
\
|
|
do \
|
|
__atg14_old = (*__atg14_memp); \
|
|
while (__builtin_expect \
|
|
(atomic_compare_and_exchange_bool_acq (__atg14_memp, \
|
|
__atg14_old | __atg14_mask,\
|
|
__atg14_old), 0)); \
|
|
\
|
|
__atg14_old & __atg14_mask; })
|
|
#endif
|
|
|
|
/* Atomically *mem &= mask. */
|
|
#ifndef atomic_and
|
|
# define atomic_and(mem, mask) \
|
|
do { \
|
|
__typeof (*(mem)) __atg15_old; \
|
|
__typeof (mem) __atg15_memp = (mem); \
|
|
__typeof (*(mem)) __atg15_mask = (mask); \
|
|
\
|
|
do \
|
|
__atg15_old = (*__atg15_memp); \
|
|
while (__builtin_expect \
|
|
(atomic_compare_and_exchange_bool_acq (__atg15_memp, \
|
|
__atg15_old & __atg15_mask, \
|
|
__atg15_old), 0)); \
|
|
} while (0)
|
|
#endif
|
|
|
|
#ifndef catomic_and
|
|
# define catomic_and(mem, mask) \
|
|
do { \
|
|
__typeof (*(mem)) __atg20_old; \
|
|
__typeof (mem) __atg20_memp = (mem); \
|
|
__typeof (*(mem)) __atg20_mask = (mask); \
|
|
\
|
|
do \
|
|
__atg20_old = (*__atg20_memp); \
|
|
while (__builtin_expect \
|
|
(catomic_compare_and_exchange_bool_acq (__atg20_memp, \
|
|
__atg20_old & __atg20_mask,\
|
|
__atg20_old), 0)); \
|
|
} while (0)
|
|
#endif
|
|
|
|
/* Atomically *mem &= mask and return the old value of *mem. */
|
|
#ifndef atomic_and_val
|
|
# define atomic_and_val(mem, mask) \
|
|
({ __typeof (*(mem)) __atg16_old; \
|
|
__typeof (mem) __atg16_memp = (mem); \
|
|
__typeof (*(mem)) __atg16_mask = (mask); \
|
|
\
|
|
do \
|
|
__atg16_old = (*__atg16_memp); \
|
|
while (__builtin_expect \
|
|
(atomic_compare_and_exchange_bool_acq (__atg16_memp, \
|
|
__atg16_old & __atg16_mask,\
|
|
__atg16_old), 0)); \
|
|
\
|
|
__atg16_old; })
|
|
#endif
|
|
|
|
/* Atomically *mem |= mask and return the old value of *mem. */
|
|
#ifndef atomic_or
|
|
# define atomic_or(mem, mask) \
|
|
do { \
|
|
__typeof (*(mem)) __atg17_old; \
|
|
__typeof (mem) __atg17_memp = (mem); \
|
|
__typeof (*(mem)) __atg17_mask = (mask); \
|
|
\
|
|
do \
|
|
__atg17_old = (*__atg17_memp); \
|
|
while (__builtin_expect \
|
|
(atomic_compare_and_exchange_bool_acq (__atg17_memp, \
|
|
__atg17_old | __atg17_mask, \
|
|
__atg17_old), 0)); \
|
|
} while (0)
|
|
#endif
|
|
|
|
#ifndef catomic_or
|
|
# define catomic_or(mem, mask) \
|
|
do { \
|
|
__typeof (*(mem)) __atg18_old; \
|
|
__typeof (mem) __atg18_memp = (mem); \
|
|
__typeof (*(mem)) __atg18_mask = (mask); \
|
|
\
|
|
do \
|
|
__atg18_old = (*__atg18_memp); \
|
|
while (__builtin_expect \
|
|
(catomic_compare_and_exchange_bool_acq (__atg18_memp, \
|
|
__atg18_old | __atg18_mask,\
|
|
__atg18_old), 0)); \
|
|
} while (0)
|
|
#endif
|
|
|
|
/* Atomically *mem |= mask and return the old value of *mem. */
|
|
#ifndef atomic_or_val
|
|
# define atomic_or_val(mem, mask) \
|
|
({ __typeof (*(mem)) __atg19_old; \
|
|
__typeof (mem) __atg19_memp = (mem); \
|
|
__typeof (*(mem)) __atg19_mask = (mask); \
|
|
\
|
|
do \
|
|
__atg19_old = (*__atg19_memp); \
|
|
while (__builtin_expect \
|
|
(atomic_compare_and_exchange_bool_acq (__atg19_memp, \
|
|
__atg19_old | __atg19_mask,\
|
|
__atg19_old), 0)); \
|
|
\
|
|
__atg19_old; })
|
|
#endif
|
|
|
|
#ifndef atomic_full_barrier
|
|
# define atomic_full_barrier() __asm ("" ::: "memory")
|
|
#endif
|
|
|
|
|
|
#ifndef atomic_read_barrier
|
|
# define atomic_read_barrier() atomic_full_barrier ()
|
|
#endif
|
|
|
|
|
|
#ifndef atomic_write_barrier
|
|
# define atomic_write_barrier() atomic_full_barrier ()
|
|
#endif
|
|
|
|
|
|
#ifndef atomic_forced_read
|
|
# define atomic_forced_read(x) \
|
|
({ __typeof (x) __x; __asm ("" : "=r" (__x) : "0" (x)); __x; })
|
|
#endif
|
|
|
|
/* This is equal to 1 iff the architecture supports 64b atomic operations. */
|
|
#ifndef __HAVE_64B_ATOMICS
|
|
#error Unable to determine if 64-bit atomics are present.
|
|
#endif
|
|
|
|
/* The following functions are a subset of the atomic operations provided by
|
|
C11. Usually, a function named atomic_OP_MO(args) is equivalent to C11's
|
|
atomic_OP_explicit(args, memory_order_MO); exceptions noted below. */
|
|
|
|
/* Each arch can request to use compiler built-ins for C11 atomics. If it
|
|
does, all atomics will be based on these. */
|
|
#if USE_ATOMIC_COMPILER_BUILTINS
|
|
|
|
/* We require 32b atomic operations; some archs also support 64b atomic
|
|
operations. */
|
|
void __atomic_link_error (void);
|
|
# if __HAVE_64B_ATOMICS == 1
|
|
# define __atomic_check_size(mem) \
|
|
if ((sizeof (*mem) != 4) && (sizeof (*mem) != 8)) \
|
|
__atomic_link_error ();
|
|
# else
|
|
# define __atomic_check_size(mem) \
|
|
if (sizeof (*mem) != 4) \
|
|
__atomic_link_error ();
|
|
# endif
|
|
/* We additionally provide 8b and 16b atomic loads and stores; we do not yet
|
|
need other atomic operations of such sizes, and restricting the support to
|
|
loads and stores makes this easier for archs that do not have native
|
|
support for atomic operations to less-than-word-sized data. */
|
|
# if __HAVE_64B_ATOMICS == 1
|
|
# define __atomic_check_size_ls(mem) \
|
|
if ((sizeof (*mem) != 1) && (sizeof (*mem) != 2) && (sizeof (*mem) != 4) \
|
|
&& (sizeof (*mem) != 8)) \
|
|
__atomic_link_error ();
|
|
# else
|
|
# define __atomic_check_size_ls(mem) \
|
|
if ((sizeof (*mem) != 1) && (sizeof (*mem) != 2) && sizeof (*mem) != 4) \
|
|
__atomic_link_error ();
|
|
# endif
|
|
|
|
# define atomic_thread_fence_acquire() \
|
|
__atomic_thread_fence (__ATOMIC_ACQUIRE)
|
|
# define atomic_thread_fence_release() \
|
|
__atomic_thread_fence (__ATOMIC_RELEASE)
|
|
# define atomic_thread_fence_seq_cst() \
|
|
__atomic_thread_fence (__ATOMIC_SEQ_CST)
|
|
|
|
# define atomic_load_relaxed(mem) \
|
|
({ __atomic_check_size_ls((mem)); \
|
|
__atomic_load_n ((mem), __ATOMIC_RELAXED); })
|
|
# define atomic_load_acquire(mem) \
|
|
({ __atomic_check_size_ls((mem)); \
|
|
__atomic_load_n ((mem), __ATOMIC_ACQUIRE); })
|
|
|
|
# define atomic_store_relaxed(mem, val) \
|
|
do { \
|
|
__atomic_check_size_ls((mem)); \
|
|
__atomic_store_n ((mem), (val), __ATOMIC_RELAXED); \
|
|
} while (0)
|
|
# define atomic_store_release(mem, val) \
|
|
do { \
|
|
__atomic_check_size_ls((mem)); \
|
|
__atomic_store_n ((mem), (val), __ATOMIC_RELEASE); \
|
|
} while (0)
|
|
|
|
/* On failure, this CAS has memory_order_relaxed semantics. */
|
|
# define atomic_compare_exchange_weak_relaxed(mem, expected, desired) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_compare_exchange_n ((mem), (expected), (desired), 1, \
|
|
__ATOMIC_RELAXED, __ATOMIC_RELAXED); })
|
|
# define atomic_compare_exchange_weak_acquire(mem, expected, desired) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_compare_exchange_n ((mem), (expected), (desired), 1, \
|
|
__ATOMIC_ACQUIRE, __ATOMIC_RELAXED); })
|
|
# define atomic_compare_exchange_weak_release(mem, expected, desired) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_compare_exchange_n ((mem), (expected), (desired), 1, \
|
|
__ATOMIC_RELEASE, __ATOMIC_RELAXED); })
|
|
|
|
# define atomic_exchange_relaxed(mem, desired) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_exchange_n ((mem), (desired), __ATOMIC_RELAXED); })
|
|
# define atomic_exchange_acquire(mem, desired) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_exchange_n ((mem), (desired), __ATOMIC_ACQUIRE); })
|
|
# define atomic_exchange_release(mem, desired) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_exchange_n ((mem), (desired), __ATOMIC_RELEASE); })
|
|
|
|
# define atomic_fetch_add_relaxed(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_add ((mem), (operand), __ATOMIC_RELAXED); })
|
|
# define atomic_fetch_add_acquire(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_add ((mem), (operand), __ATOMIC_ACQUIRE); })
|
|
# define atomic_fetch_add_release(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_add ((mem), (operand), __ATOMIC_RELEASE); })
|
|
# define atomic_fetch_add_acq_rel(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_add ((mem), (operand), __ATOMIC_ACQ_REL); })
|
|
|
|
# define atomic_fetch_and_relaxed(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_and ((mem), (operand), __ATOMIC_RELAXED); })
|
|
# define atomic_fetch_and_acquire(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_and ((mem), (operand), __ATOMIC_ACQUIRE); })
|
|
# define atomic_fetch_and_release(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_and ((mem), (operand), __ATOMIC_RELEASE); })
|
|
|
|
# define atomic_fetch_or_relaxed(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_or ((mem), (operand), __ATOMIC_RELAXED); })
|
|
# define atomic_fetch_or_acquire(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_or ((mem), (operand), __ATOMIC_ACQUIRE); })
|
|
# define atomic_fetch_or_release(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_or ((mem), (operand), __ATOMIC_RELEASE); })
|
|
|
|
# define atomic_fetch_xor_release(mem, operand) \
|
|
({ __atomic_check_size((mem)); \
|
|
__atomic_fetch_xor ((mem), (operand), __ATOMIC_RELEASE); })
|
|
|
|
#else /* !USE_ATOMIC_COMPILER_BUILTINS */
|
|
|
|
/* By default, we assume that read, write, and full barriers are equivalent
|
|
to acquire, release, and seq_cst barriers. Archs for which this does not
|
|
hold have to provide custom definitions of the fences. */
|
|
# ifndef atomic_thread_fence_acquire
|
|
# define atomic_thread_fence_acquire() atomic_read_barrier ()
|
|
# endif
|
|
# ifndef atomic_thread_fence_release
|
|
# define atomic_thread_fence_release() atomic_write_barrier ()
|
|
# endif
|
|
# ifndef atomic_thread_fence_seq_cst
|
|
# define atomic_thread_fence_seq_cst() atomic_full_barrier ()
|
|
# endif
|
|
|
|
# ifndef atomic_load_relaxed
|
|
# define atomic_load_relaxed(mem) \
|
|
({ __typeof ((__typeof (*(mem))) *(mem)) __atg100_val; \
|
|
__asm ("" : "=r" (__atg100_val) : "0" (*(mem))); \
|
|
__atg100_val; })
|
|
# endif
|
|
# ifndef atomic_load_acquire
|
|
# define atomic_load_acquire(mem) \
|
|
({ __typeof (*(mem)) __atg101_val = atomic_load_relaxed (mem); \
|
|
atomic_thread_fence_acquire (); \
|
|
__atg101_val; })
|
|
# endif
|
|
|
|
# ifndef atomic_store_relaxed
|
|
/* XXX Use inline asm here? */
|
|
# define atomic_store_relaxed(mem, val) do { *(mem) = (val); } while (0)
|
|
# endif
|
|
# ifndef atomic_store_release
|
|
# define atomic_store_release(mem, val) \
|
|
do { \
|
|
atomic_thread_fence_release (); \
|
|
atomic_store_relaxed ((mem), (val)); \
|
|
} while (0)
|
|
# endif
|
|
|
|
/* On failure, this CAS has memory_order_relaxed semantics. */
|
|
/* XXX This potentially has one branch more than necessary, but archs
|
|
currently do not define a CAS that returns both the previous value and
|
|
the success flag. */
|
|
# ifndef atomic_compare_exchange_weak_acquire
|
|
# define atomic_compare_exchange_weak_acquire(mem, expected, desired) \
|
|
({ typeof (*(expected)) __atg102_expected = *(expected); \
|
|
*(expected) = \
|
|
atomic_compare_and_exchange_val_acq ((mem), (desired), *(expected)); \
|
|
*(expected) == __atg102_expected; })
|
|
# endif
|
|
# ifndef atomic_compare_exchange_weak_relaxed
|
|
/* XXX Fall back to CAS with acquire MO because archs do not define a weaker
|
|
CAS. */
|
|
# define atomic_compare_exchange_weak_relaxed(mem, expected, desired) \
|
|
atomic_compare_exchange_weak_acquire ((mem), (expected), (desired))
|
|
# endif
|
|
# ifndef atomic_compare_exchange_weak_release
|
|
# define atomic_compare_exchange_weak_release(mem, expected, desired) \
|
|
({ typeof (*(expected)) __atg103_expected = *(expected); \
|
|
*(expected) = \
|
|
atomic_compare_and_exchange_val_rel ((mem), (desired), *(expected)); \
|
|
*(expected) == __atg103_expected; })
|
|
# endif
|
|
|
|
/* XXX Fall back to acquire MO because archs do not define a weaker
|
|
atomic_exchange. */
|
|
# ifndef atomic_exchange_relaxed
|
|
# define atomic_exchange_relaxed(mem, val) \
|
|
atomic_exchange_acq ((mem), (val))
|
|
# endif
|
|
# ifndef atomic_exchange_acquire
|
|
# define atomic_exchange_acquire(mem, val) \
|
|
atomic_exchange_acq ((mem), (val))
|
|
# endif
|
|
# ifndef atomic_exchange_release
|
|
# define atomic_exchange_release(mem, val) \
|
|
atomic_exchange_rel ((mem), (val))
|
|
# endif
|
|
|
|
# ifndef atomic_fetch_add_acquire
|
|
# define atomic_fetch_add_acquire(mem, operand) \
|
|
atomic_exchange_and_add_acq ((mem), (operand))
|
|
# endif
|
|
# ifndef atomic_fetch_add_relaxed
|
|
/* XXX Fall back to acquire MO because the MO semantics of
|
|
atomic_exchange_and_add are not documented; the generic version falls back
|
|
to atomic_exchange_and_add_acq if atomic_exchange_and_add is not defined,
|
|
and vice versa. */
|
|
# define atomic_fetch_add_relaxed(mem, operand) \
|
|
atomic_fetch_add_acquire ((mem), (operand))
|
|
# endif
|
|
# ifndef atomic_fetch_add_release
|
|
# define atomic_fetch_add_release(mem, operand) \
|
|
atomic_exchange_and_add_rel ((mem), (operand))
|
|
# endif
|
|
# ifndef atomic_fetch_add_acq_rel
|
|
# define atomic_fetch_add_acq_rel(mem, operand) \
|
|
({ atomic_thread_fence_release (); \
|
|
atomic_exchange_and_add_acq ((mem), (operand)); })
|
|
# endif
|
|
|
|
/* XXX Fall back to acquire MO because archs do not define a weaker
|
|
atomic_and_val. */
|
|
# ifndef atomic_fetch_and_relaxed
|
|
# define atomic_fetch_and_relaxed(mem, operand) \
|
|
atomic_fetch_and_acquire ((mem), (operand))
|
|
# endif
|
|
/* XXX The default for atomic_and_val has acquire semantics, but this is not
|
|
documented. */
|
|
# ifndef atomic_fetch_and_acquire
|
|
# define atomic_fetch_and_acquire(mem, operand) \
|
|
atomic_and_val ((mem), (operand))
|
|
# endif
|
|
# ifndef atomic_fetch_and_release
|
|
/* XXX This unnecessarily has acquire MO. */
|
|
# define atomic_fetch_and_release(mem, operand) \
|
|
({ atomic_thread_fence_release (); \
|
|
atomic_and_val ((mem), (operand)); })
|
|
# endif
|
|
|
|
/* XXX The default for atomic_or_val has acquire semantics, but this is not
|
|
documented. */
|
|
# ifndef atomic_fetch_or_acquire
|
|
# define atomic_fetch_or_acquire(mem, operand) \
|
|
atomic_or_val ((mem), (operand))
|
|
# endif
|
|
/* XXX Fall back to acquire MO because archs do not define a weaker
|
|
atomic_or_val. */
|
|
# ifndef atomic_fetch_or_relaxed
|
|
# define atomic_fetch_or_relaxed(mem, operand) \
|
|
atomic_fetch_or_acquire ((mem), (operand))
|
|
# endif
|
|
/* XXX Contains an unnecessary acquire MO because archs do not define a weaker
|
|
atomic_or_val. */
|
|
# ifndef atomic_fetch_or_release
|
|
# define atomic_fetch_or_release(mem, operand) \
|
|
({ atomic_thread_fence_release (); \
|
|
atomic_fetch_or_acquire ((mem), (operand)); })
|
|
# endif
|
|
|
|
# ifndef atomic_fetch_xor_release
|
|
/* Failing the atomic_compare_exchange_weak_release reloads the value in
|
|
__atg104_expected, so we need only do the XOR again and retry. */
|
|
# define atomic_fetch_xor_release(mem, operand) \
|
|
({ __typeof (mem) __atg104_memp = (mem); \
|
|
__typeof (*(mem)) __atg104_expected = (*__atg104_memp); \
|
|
__typeof (*(mem)) __atg104_desired; \
|
|
__typeof (*(mem)) __atg104_op = (operand); \
|
|
\
|
|
do \
|
|
__atg104_desired = __atg104_expected ^ __atg104_op; \
|
|
while (__glibc_unlikely \
|
|
(atomic_compare_exchange_weak_release ( \
|
|
__atg104_memp, &__atg104_expected, __atg104_desired) \
|
|
== 0)); \
|
|
__atg104_expected; })
|
|
#endif
|
|
|
|
#endif /* !USE_ATOMIC_COMPILER_BUILTINS */
|
|
|
|
/* This operation does not affect synchronization semantics but can be used
|
|
in the body of a spin loop to potentially improve its efficiency. */
|
|
#ifndef atomic_spin_nop
|
|
# define atomic_spin_nop() do { /* nothing */ } while (0)
|
|
#endif
|
|
|
|
/* ATOMIC_EXCHANGE_USES_CAS is non-zero if atomic_exchange operations
|
|
are implemented based on a CAS loop; otherwise, this is zero and we assume
|
|
that the atomic_exchange operations could provide better performance
|
|
than a CAS loop. */
|
|
#ifndef ATOMIC_EXCHANGE_USES_CAS
|
|
# error ATOMIC_EXCHANGE_USES_CAS has to be defined.
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#endif
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#endif /* atomic.h */
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