Retro68/gcc/libcilkrts/runtime/worker_mutex.c
2014-09-21 19:33:12 +02:00

122 lines
4.1 KiB
C

/* worker_mutex.c -*-C-*-
*
*************************************************************************
*
* @copyright
* Copyright (C) 2009-2013, Intel Corporation
* All rights reserved.
*
* @copyright
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Intel Corporation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* @copyright
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
* WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
**************************************************************************/
#include "worker_mutex.h"
#include "bug.h"
#include "os.h"
#include "stats.h"
/* m->lock == 1 means that mutex M is locked */
#define TRY_ACQUIRE(m) (__cilkrts_xchg(&(m)->lock, 1) == 0)
/* ICC 11.1+ understands release semantics and generates an
ordinary store with a software memory barrier. */
#if __ICC >= 1110
#define RELEASE(m) __sync_lock_release(&(m)->lock)
#else
#define RELEASE(m) __cilkrts_xchg(&(m)->lock, 0)
#endif
void __cilkrts_mutex_init(struct mutex *m)
{
m->owner = 0;
// Use a simple assignment so Inspector doesn't bug us about the
// interlocked exchange doing a read of an uninitialized variable.
// By definition there can't be a race when we're initializing the
// lock...
m->lock = 0;
}
void __cilkrts_mutex_lock(__cilkrts_worker *w, struct mutex *m)
{
int count;
const int maxspin = 1000; /* SWAG */
NOTE_INTERVAL(w, INTERVAL_MUTEX_LOCK);
if (!TRY_ACQUIRE(m)) {
START_INTERVAL(w, INTERVAL_MUTEX_LOCK_SPINNING);
count = 0;
do {
do {
__cilkrts_short_pause();
if (++count >= maxspin) {
STOP_INTERVAL(w, INTERVAL_MUTEX_LOCK_SPINNING);
START_INTERVAL(w, INTERVAL_MUTEX_LOCK_YIELDING);
/* let the OS reschedule every once in a while */
__cilkrts_yield();
STOP_INTERVAL(w, INTERVAL_MUTEX_LOCK_YIELDING);
START_INTERVAL(w, INTERVAL_MUTEX_LOCK_SPINNING);
count = 0;
}
} while (m->lock != 0);
} while (!TRY_ACQUIRE(m));
STOP_INTERVAL(w, INTERVAL_MUTEX_LOCK_SPINNING);
}
CILK_ASSERT(m->owner == 0);
m->owner = w;
}
int __cilkrts_mutex_trylock(__cilkrts_worker *w, struct mutex *m)
{
NOTE_INTERVAL(w, INTERVAL_MUTEX_TRYLOCK);
if (TRY_ACQUIRE(m)) {
CILK_ASSERT(m->owner == 0);
m->owner = w;
return 1;
} else {
return 0;
}
}
void __cilkrts_mutex_unlock(__cilkrts_worker *w, struct mutex *m)
{
CILK_ASSERT(m->owner == w);
m->owner = 0;
RELEASE(m);
}
void __cilkrts_mutex_destroy(__cilkrts_worker *w, struct mutex *m)
{
(void)w; /* unused */
(void)m; /* unused */
}
/* End worker_mutex.c */