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/* Single thread optimization, Linux version.
Copyright (C) 2019-2021 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 _SINGLE_THREAD_H
#define _SINGLE_THREAD_H
/* The default way to check if the process is single thread is by using the
pthread_t 'multiple_threads' field. However, for some architectures it is
faster to either use an extra field on TCB or global variables (the TCB
field is also used on x86 for some single-thread atomic optimizations).
The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single thread
check to use global variables instead of the pthread_t field. */
#ifndef __ASSEMBLER__
extern int __libc_multiple_threads;
libc_hidden_proto (__libc_multiple_threads)
#endif
#if !defined SINGLE_THREAD_BY_GLOBAL || IS_IN (rtld)
# define SINGLE_THREAD_P \
(THREAD_GETMEM (THREAD_SELF, header.multiple_threads) == 0)
#else
# define SINGLE_THREAD_P (__libc_multiple_threads == 0)
#endif
#define RTLD_SINGLE_THREAD_P SINGLE_THREAD_P
#endif /* _SINGLE_THREAD_H */
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