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/* elide.h: Generic lock elision support for powerpc.
Copyright (C) 2015 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_PPC_H
# define ELIDE_PPC_H
#ifdef ENABLE_LOCK_ELISION
# include <htm.h>
# include <elision-conf.h>
/* Returns true if the lock defined by is_lock_free as elided.
ADAPT_COUNT is a pointer to per-lock state variable. */
static inline bool
__elide_lock (uint8_t *adapt_count, int is_lock_free)
{
if (*adapt_count > 0)
{
(*adapt_count)--;
return false;
}
for (int i = __elision_aconf.try_tbegin; i > 0; i--)
{
if (__builtin_tbegin (0))
{
if (is_lock_free)
return true;
/* Lock was busy. */
__builtin_tabort (_ABORT_LOCK_BUSY);
}
else
{
/* A persistent failure indicates that a retry will probably
result in another failure. Use normal locking now and
for the next couple of calls. */
if (_TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ()))
{
if (__elision_aconf.skip_lock_internal_abort > 0)
*adapt_count = __elision_aconf.skip_lock_internal_abort;
break;
}
/* Same logic as above, but for a number of temporary failures in a
a row. */
else if (__elision_aconf.skip_lock_out_of_tbegin_retries > 0
&& __elision_aconf.try_tbegin > 0)
*adapt_count = __elision_aconf.skip_lock_out_of_tbegin_retries;
}
}
return false;
}
# define ELIDE_LOCK(adapt_count, is_lock_free) \
__elide_lock (&(adapt_count), is_lock_free)
static inline bool
__elide_trylock (uint8_t *adapt_count, int is_lock_free, int write)
{
if (__elision_aconf.try_tbegin > 0)
{
if (write)
__builtin_tabort (_ABORT_NESTED_TRYLOCK);
return __elide_lock (adapt_count, is_lock_free);
}
return false;
}
# define ELIDE_TRYLOCK(adapt_count, is_lock_free, write) \
__elide_trylock (&(adapt_count), is_lock_free, write)
static inline bool
__elide_unlock (int is_lock_free)
{
if (is_lock_free)
{
__builtin_tend (0);
return true;
}
return false;
}
# define ELIDE_UNLOCK(is_lock_free) \
__elide_unlock (is_lock_free)
# else
# define ELIDE_LOCK(adapt_count, is_lock_free) 0
# define ELIDE_TRYLOCK(adapt_count, is_lock_free, write) 0
# define ELIDE_UNLOCK(is_lock_free) 0
#endif /* ENABLE_LOCK_ELISION */
#endif
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