diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/x86/force-elision.h')
| -rw-r--r-- | sysdeps/unix/sysv/linux/x86/force-elision.h | 62 |
1 files changed, 0 insertions, 62 deletions
diff --git a/sysdeps/unix/sysv/linux/x86/force-elision.h b/sysdeps/unix/sysv/linux/x86/force-elision.h deleted file mode 100644 index 3c0a0e0ac5..0000000000 --- a/sysdeps/unix/sysv/linux/x86/force-elision.h +++ /dev/null @@ -1,62 +0,0 @@ -/* force-elision.h: Automatic enabling of elision for mutexes - Copyright (C) 2013-2021 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/>. */ - -/* Automatically enable elision for existing user lock kinds. */ -#define FORCE_ELISION(m, s) \ - if (__pthread_force_elision) \ - { \ - /* See concurrency notes regarding __kind in \ - struct __pthread_mutex_s in \ - sysdeps/nptl/bits/thread-shared-types.h. \ - \ - There are the following cases for the kind of a mutex \ - (The mask PTHREAD_MUTEX_ELISION_FLAGS_NP covers the flags \ - PTHREAD_MUTEX_ELISION_NP and PTHREAD_MUTEX_NO_ELISION_NP where \ - only one of both flags can be set): \ - - both flags are not set: \ - This is the first lock operation for this mutex. Enable \ - elision as it is not enabled so far. \ - Note: It can happen that multiple threads are calling e.g. \ - pthread_mutex_lock at the same time as the first lock \ - operation for this mutex. Then elision is enabled for this \ - mutex by multiple threads. Storing with relaxed MO is enough \ - as all threads will store the same new value for the kind of \ - the mutex. But we have to ensure that we always use the \ - elision path regardless if this thread has enabled elision or \ - another one. \ - \ - - PTHREAD_MUTEX_ELISION_NP flag is set: \ - Elision was already enabled for this mutex by a previous lock \ - operation. See case above. Just use the elision path. \ - \ - - PTHREAD_MUTEX_NO_ELISION_NP flag is set: \ - Elision was explicitly disabled by pthread_mutexattr_settype. \ - Do not use the elision path. \ - Note: The flag PTHREAD_MUTEX_NO_ELISION_NP will never be \ - changed after mutex initialization. */ \ - int mutex_kind = atomic_load_relaxed (&((m)->__data.__kind)); \ - if ((mutex_kind & PTHREAD_MUTEX_ELISION_FLAGS_NP) == 0) \ - { \ - mutex_kind |= PTHREAD_MUTEX_ELISION_NP; \ - atomic_store_relaxed (&((m)->__data.__kind), mutex_kind); \ - } \ - if ((mutex_kind & PTHREAD_MUTEX_ELISION_NP) != 0) \ - { \ - s; \ - } \ - } |