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[/] [openrisc/] [trunk/] [gnu-old/] [gcc-4.2.2/] [libgomp/] [config/] [linux/] [lock.c] - Blame information for rev 867

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/* Copyright (C) 2005 Free Software Foundation, Inc.
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   Contributed by Richard Henderson <rth@redhat.com>.
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   This file is part of the GNU OpenMP Library (libgomp).
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   Libgomp is free software; you can redistribute it and/or modify it
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   under the terms of the GNU Lesser General Public License as published by
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   the Free Software Foundation; either version 2.1 of the License, or
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   (at your option) any later version.
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   Libgomp is distributed in the hope that it will be useful, but WITHOUT ANY
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   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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   FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
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   more details.
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   You should have received a copy of the GNU Lesser General Public License
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   along with libgomp; see the file COPYING.LIB.  If not, write to the
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   Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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   MA 02110-1301, USA.  */
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/* As a special exception, if you link this library with other files, some
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   of which are compiled with GCC, to produce an executable, this library
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   does not by itself cause the resulting executable to be covered by the
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   GNU General Public License.  This exception does not however invalidate
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   any other reasons why the executable file might be covered by the GNU
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   General Public License.  */
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/* This is a Linux specific implementation of the public OpenMP locking
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   primitives.  This implementation uses atomic instructions and the futex
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   syscall.  */
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#include "libgomp.h"
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#include <string.h>
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#include <unistd.h>
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#include <sys/syscall.h>
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#include "futex.h"
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/* The internal gomp_mutex_t and the external non-recursive omp_lock_t
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   have the same form.  Re-use it.  */
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void
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omp_init_lock (omp_lock_t *lock)
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{
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  gomp_mutex_init (lock);
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}
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void
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omp_destroy_lock (omp_lock_t *lock)
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{
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  gomp_mutex_destroy (lock);
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}
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void
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omp_set_lock (omp_lock_t *lock)
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{
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  gomp_mutex_lock (lock);
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}
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void
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omp_unset_lock (omp_lock_t *lock)
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{
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  gomp_mutex_unlock (lock);
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}
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int
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omp_test_lock (omp_lock_t *lock)
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{
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  return __sync_bool_compare_and_swap (lock, 0, 1);
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}
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/* The external recursive omp_nest_lock_t form requires additional work.  */
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/* We need an integer to uniquely identify this thread.  Most generally
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   this is the thread's TID, which ideally we'd get this straight from
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   the TLS block where glibc keeps it.  Unfortunately, we can't get at
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   that directly.
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   If we don't support (or have disabled) TLS, one function call is as
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   good (or bad) as any other.  Use the syscall all the time.
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   On an ILP32 system (defined here as not LP64), we can make do with
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   any thread-local pointer.  Ideally we'd use the TLS base address,
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   since that requires the least amount of arithmetic, but that's not
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   always available directly.  Make do with the gomp_thread pointer
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   since it's handy.  */
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#if !defined (HAVE_TLS)
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static inline int gomp_tid (void)
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{
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  return syscall (SYS_gettid);
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}
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#elif !defined(__LP64__)
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static inline int gomp_tid (void)
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{
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  return (int) gomp_thread ();
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}
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#else
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static __thread int tid_cache;
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static inline int gomp_tid (void)
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{
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  int tid = tid_cache;
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  if (__builtin_expect (tid == 0, 0))
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    tid_cache = tid = syscall (SYS_gettid);
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  return tid;
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}
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#endif
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void
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omp_init_nest_lock (omp_nest_lock_t *lock)
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{
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  memset (lock, 0, sizeof (lock));
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}
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void
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omp_destroy_nest_lock (omp_nest_lock_t *lock)
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{
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}
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void
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omp_set_nest_lock (omp_nest_lock_t *lock)
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{
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  int otid, tid = gomp_tid ();
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  while (1)
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    {
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      otid = __sync_val_compare_and_swap (&lock->owner, 0, tid);
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      if (otid == 0)
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        {
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          lock->count = 1;
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          return;
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        }
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      if (otid == tid)
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        {
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          lock->count++;
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          return;
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        }
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      futex_wait (&lock->owner, otid);
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    }
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}
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void
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omp_unset_nest_lock (omp_nest_lock_t *lock)
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{
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  /* ??? Validate that we own the lock here.  */
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  if (--lock->count == 0)
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    {
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      __sync_lock_release (&lock->owner);
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      futex_wake (&lock->owner, 1);
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    }
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}
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int
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omp_test_nest_lock (omp_nest_lock_t *lock)
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{
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  int otid, tid = gomp_tid ();
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  otid = __sync_val_compare_and_swap (&lock->owner, 0, tid);
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  if (otid == 0)
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    {
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      lock->count = 1;
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      return 1;
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    }
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  if (otid == tid)
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    return ++lock->count;
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  return 0;
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}
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ialias (omp_init_lock)
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ialias (omp_init_nest_lock)
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ialias (omp_destroy_lock)
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ialias (omp_destroy_nest_lock)
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ialias (omp_set_lock)
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ialias (omp_set_nest_lock)
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ialias (omp_unset_lock)
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ialias (omp_unset_nest_lock)
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ialias (omp_test_lock)
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ialias (omp_test_nest_lock)

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