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Diffstat (limited to 'sysdeps/x86/elide.h')
| -rw-r--r-- | sysdeps/x86/elide.h | 119 |
1 files changed, 0 insertions, 119 deletions
diff --git a/sysdeps/x86/elide.h b/sysdeps/x86/elide.h deleted file mode 100644 index 53de41836e..0000000000 --- a/sysdeps/x86/elide.h +++ /dev/null @@ -1,119 +0,0 @@ -/* elide.h: Generic lock elision support. - Copyright (C) 2014-2017 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/>. */ -#ifndef ELIDE_H -#define ELIDE_H 1 - -#include <hle.h> -#include <elision-conf.h> -#include <atomic.h> - - -/* Adapt elision with ADAPT_COUNT and STATUS and decide retries. */ - -static inline bool -elision_adapt(signed char *adapt_count, unsigned int status) -{ - if (status & _XABORT_RETRY) - return false; - if ((status & _XABORT_EXPLICIT) - && _XABORT_CODE (status) == _ABORT_LOCK_BUSY) - { - /* Right now we skip here. Better would be to wait a bit - and retry. This likely needs some spinning. Be careful - to avoid writing the lock. - Using relaxed MO and separate atomic accesses is sufficient because - adapt_count is just a hint. */ - if (atomic_load_relaxed (adapt_count) != __elision_aconf.skip_lock_busy) - atomic_store_relaxed (adapt_count, __elision_aconf.skip_lock_busy); - } - /* Internal abort. There is no chance for retry. - Use the normal locking and next time use lock. - Be careful to avoid writing to the lock. See above for MO. */ - else if (atomic_load_relaxed (adapt_count) - != __elision_aconf.skip_lock_internal_abort) - atomic_store_relaxed (adapt_count, - __elision_aconf.skip_lock_internal_abort); - return true; -} - -/* is_lock_free must be executed inside the transaction */ - -/* Returns true if lock defined by IS_LOCK_FREE was elided. - ADAPT_COUNT is a per-lock state variable; it must be accessed atomically - to avoid data races but is just a hint, so using relaxed MO and separate - atomic loads and stores instead of atomic read-modify-write operations is - sufficient. */ - -#define ELIDE_LOCK(adapt_count, is_lock_free) \ - ({ \ - int ret = 0; \ - \ - if (atomic_load_relaxed (&(adapt_count)) <= 0) \ - { \ - for (int i = __elision_aconf.retry_try_xbegin; i > 0; i--) \ - { \ - unsigned int status; \ - if ((status = _xbegin ()) == _XBEGIN_STARTED) \ - { \ - if (is_lock_free) \ - { \ - ret = 1; \ - break; \ - } \ - _xabort (_ABORT_LOCK_BUSY); \ - } \ - if (!elision_adapt (&(adapt_count), status)) \ - break; \ - } \ - } \ - else \ - atomic_store_relaxed (&(adapt_count), \ - atomic_load_relaxed (&(adapt_count)) - 1); \ - ret; \ - }) - -/* Returns true if lock defined by IS_LOCK_FREE was try-elided. - ADAPT_COUNT is a per-lock state variable. */ - -#define ELIDE_TRYLOCK(adapt_count, is_lock_free, write) ({ \ - int ret = 0; \ - if (__elision_aconf.retry_try_xbegin > 0) \ - { \ - if (write) \ - _xabort (_ABORT_NESTED_TRYLOCK); \ - ret = ELIDE_LOCK (adapt_count, is_lock_free); \ - } \ - ret; \ - }) - -/* Returns true if lock defined by IS_LOCK_FREE was elided. The call - to _xend crashes if the application incorrectly tries to unlock a - lock which has not been locked. */ - -#define ELIDE_UNLOCK(is_lock_free) \ - ({ \ - int ret = 0; \ - if (is_lock_free) \ - { \ - _xend (); \ - ret = 1; \ - } \ - ret; \ - }) - -#endif |