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glibc/sysdeps/generic/malloc-machine.h
Adhemerval Zanella 70ee250fb8 atomic: Consolidate atomic_full_barrier implementation
All ABIs save for sparcv9 and s390 defines it to __sync_synchronize,
which can be mapped to __atomic_thread_fence (__ATOMIC_SEQ_CST).

For Sparc, it uses a stricter #StoreStore|#LoadStore|#StoreLoad|#LoadLoad
instead of the #StoreLoad generated by __sync_synchronize.

For s390x, it defaults to a memory barrier where __sync_synchronize
emits a 'bcr 15,0' (which the manual describes as pipeline synchronization).

The barrier is used only in one place (pthread_mutex_setprioceiling),
and using a stricter barrier for s390 is ok performance-wise.

Co-authored-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>
2025-11-04 04:14:01 -03:00

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1.3 KiB
C

/* Basic platform-independent macro definitions for mutexes,
thread-specific data and parameters for malloc.
Copyright (C) 2003-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _GENERIC_MALLOC_MACHINE_H
#define _GENERIC_MALLOC_MACHINE_H
#include <atomic.h>
#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 DEFAULT_TOP_PAD
# define DEFAULT_TOP_PAD 131072
#endif
#endif /* !defined(_GENERIC_MALLOC_MACHINE_H) */