| /* Single-thread optimization definitions. Linux version. |
| Copyright (C) 2017-2018 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) |
