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- /* Single-thread optimization definitions. Linux version.
- Copyright (C) 2017-2019 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
- <http://www.gnu.org/licenses/>. */
- #include <sysdep.h>
- #include <tls.h>
- #include <nptl/pthreadP.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 varibles
- (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. */
- #ifdef SINGLE_THREAD_BY_GLOBAL
- # if IS_IN (libc)
- extern int __libc_multiple_threads;
- # define SINGLE_THREAD_P \
- __glibc_likely (__libc_multiple_threads == 0)
- # elif IS_IN (libpthread)
- extern int __pthread_multiple_threads;
- # define SINGLE_THREAD_P \
- __glibc_likely (__pthread_multiple_threads == 0)
- # elif IS_IN (librt)
- # define SINGLE_THREAD_P \
- __glibc_likely (THREAD_GETMEM (THREAD_SELF, \
- header.multiple_threads) == 0)
- # else
- /* For rtld, et cetera. */
- # define SINGLE_THREAD_P (1)
- # endif
- #else /* SINGLE_THREAD_BY_GLOBAL */
- # if IS_IN (libc) || IS_IN (libpthread) || IS_IN (librt)
- # define SINGLE_THREAD_P \
- __glibc_likely (THREAD_GETMEM (THREAD_SELF, \
- header.multiple_threads) == 0)
- # else
- /* For rtld, et cetera. */
- # define SINGLE_THREAD_P (1)
- # endif
- #endif /* SINGLE_THREAD_BY_GLOBAL */
- #define RTLD_SINGLE_THREAD_P \
- __glibc_likely (THREAD_GETMEM (THREAD_SELF, \
- header.multiple_threads) == 0)
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