This is the mutex part. Depends on
http://gcc.gnu.org/ml/gcc-patches/2011-11/msg02454.html for MEMMODEL_*
values.
* config/linux/mutex.h: Use atomic rather than sync builtins.
* config/linux/mutex.c: Likewise. Comment. Use -1 for waiting state.
* config/linux/omp-lock.h: Comment fix.
* config/linux/arm/mutex.h: Delete.
* config/linux/powerpc/mutex.h: Delete.
* config/linux/ia64/mutex.h: Delete.
* config/linux/mips/mutex.h: Delete.
Index: libgomp/config/linux/mutex.h
===================================================================
--- libgomp/config/linux/mutex.h (revision 181718)
+++ libgomp/config/linux/mutex.h (working copy)
@@ -33,39 +33,35 @@ typedef int gomp_mutex_t;
#define GOMP_MUTEX_INIT_0 1
-static inline void gomp_mutex_init (gomp_mutex_t *mutex)
+extern void gomp_mutex_lock_slow (gomp_mutex_t *mutex, int);
+extern void gomp_mutex_unlock_slow (gomp_mutex_t *mutex);
+
+static inline void
+gomp_mutex_init (gomp_mutex_t *mutex)
{
*mutex = 0;
}
-extern void gomp_mutex_lock_slow (gomp_mutex_t *mutex, int);
-static inline void gomp_mutex_lock (gomp_mutex_t *mutex)
+static inline void
+gomp_mutex_destroy (gomp_mutex_t *mutex)
{
- int oldval = __sync_val_compare_and_swap (mutex, 0, 1);
- if (__builtin_expect (oldval, 0))
- gomp_mutex_lock_slow (mutex, oldval);
}
-extern void gomp_mutex_unlock_slow (gomp_mutex_t *mutex);
-static inline void gomp_mutex_unlock (gomp_mutex_t *mutex)
+static inline void
+gomp_mutex_lock (gomp_mutex_t *mutex)
{
- /* Warning: By definition __sync_lock_test_and_set() does not have
- proper memory barrier semantics for a mutex unlock operation.
- However, this default implementation is written assuming that it
- does, which is true for some targets.
-
- Targets that require additional memory barriers before
- __sync_lock_test_and_set to achieve the release semantics of
- mutex unlock, are encouraged to include
- "config/linux/ia64/mutex.h" in a target specific mutex.h instead
- of using this file. */
- int val = __sync_lock_test_and_set (mutex, 0);
- if (__builtin_expect (val > 1, 0))
- gomp_mutex_unlock_slow (mutex);
+ int oldval = 0;
+ __atomic_compare_exchange_4 (mutex, &oldval, 1, false,
+ MEMMODEL_ACQUIRE, MEMMODEL_RELAXED);
+ if (__builtin_expect (oldval != 0, 0))
+ gomp_mutex_lock_slow (mutex, oldval);
}
-static inline void gomp_mutex_destroy (gomp_mutex_t *mutex)
+static inline void
+gomp_mutex_unlock (gomp_mutex_t *mutex)
{
+ int wait = __atomic_exchange_4 (mutex, 0, MEMMODEL_RELEASE);
+ if (__builtin_expect (wait < 0, 0))
+ gomp_mutex_unlock_slow (mutex);
}
-
#endif /* GOMP_MUTEX_H */
Index: libgomp/config/linux/mutex.c
===================================================================
--- libgomp/config/linux/mutex.c (revision 181718)
+++ libgomp/config/linux/mutex.c (working copy)
@@ -34,25 +34,33 @@ long int gomp_futex_wait = FUTEX_WAIT |
void
gomp_mutex_lock_slow (gomp_mutex_t *mutex, int oldval)
{
+ /* First loop spins a while. */
while (oldval == 1)
{
if (do_spin (mutex, 1))
{
- oldval = __sync_lock_test_and_set (mutex, 2);
+ /* Spin timeout, nothing changed. Set waiting flag. */
+ oldval = __atomic_exchange_4 (mutex, -1, MEMMODEL_ACQUIRE);
if (oldval == 0)
return;
- futex_wait (mutex, 2);
+ futex_wait (mutex, -1);
break;
}
else
{
- oldval = __sync_val_compare_and_swap (mutex, 0, 1);
+ /* Something changed. If now unlocked, we're good to go. */
+ oldval = 0;
+ __atomic_compare_exchange_4 (mutex, &oldval, 1, false,
+ MEMMODEL_ACQUIRE, MEMMODEL_RELAXED);
if (oldval == 0)
return;
}
}
- while ((oldval = __sync_lock_test_and_set (mutex, 2)))
- do_wait (mutex, 2);
+
+ /* Second loop waits until mutex is unlocked. We always exit this
+ loop with wait flag set, so next unlock will awaken a thread. */
+ while ((oldval = __atomic_exchange_4 (mutex, -1, MEMMODEL_ACQUIRE)))
+ do_wait (mutex, -1);
}
void
Index: libgomp/config/linux/omp-lock.h
===================================================================
--- libgomp/config/linux/omp-lock.h (revision 181718)
+++ libgomp/config/linux/omp-lock.h (working copy)
@@ -3,8 +3,8 @@
structures without polluting the namespace.
When using the Linux futex primitive, non-recursive locks require
- only one int. Recursive locks require we identify the owning task
- and so require one int and a pointer. */
+ one int. Recursive locks require we identify the owning task
+ and so require in addition one int and a pointer. */
typedef int omp_lock_t;
typedef struct { int lock, count; void *owner; } omp_nest_lock_t;
Index: libgomp/config/linux/arm/mutex.h
===================================================================
--- libgomp/config/linux/arm/mutex.h (revision 181718)
+++ libgomp/config/linux/arm/mutex.h (working copy)
@@ -1,28 +0,0 @@
-/* Copyright (C) 2010 Free Software Foundation, Inc.
- Contributed by ARM Ltd.
-
- This file is part of the GNU OpenMP Library (libgomp).
-
- Libgomp is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3, or (at your option)
- any later version.
-
- Libgomp 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 General Public License for
- more details.
-
- Under Section 7 of GPL version 3, you are granted additional
- permissions described in the GCC Runtime Library Exception, version
- 3.1, as published by the Free Software Foundation.
-
- You should have received a copy of the GNU General Public License and
- a copy of the GCC Runtime Library Exception along with this program;
- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
- <http://www.gnu.org/licenses/>. */
-
-/* ARM needs the same correct usage of __sync_synchronize and
- __sync_lock_test_and_set as ia64. So we just use its mutex.h. */
-
-#include "config/linux/ia64/mutex.h"
Index: libgomp/config/linux/powerpc/mutex.h
===================================================================
--- libgomp/config/linux/powerpc/mutex.h (revision 181718)
+++ libgomp/config/linux/powerpc/mutex.h (working copy)
@@ -1,2 +0,0 @@
-/* On PowerPC __sync_lock_test_and_set isn't a full barrier. */
-#include "config/linux/ia64/mutex.h"
Index: libgomp/config/linux/ia64/mutex.h
===================================================================
--- libgomp/config/linux/ia64/mutex.h (revision 181718)
+++ libgomp/config/linux/ia64/mutex.h (working copy)
@@ -1,66 +0,0 @@
-/* Copyright (C) 2005, 2008, 2009, 2011 Free Software Foundation, Inc.
- Contributed by Richard Henderson <r...@redhat.com>.
-
- This file is part of the GNU OpenMP Library (libgomp).
-
- Libgomp is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3, or (at your option)
- any later version.
-
- Libgomp 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 General Public License for
- more details.
-
- Under Section 7 of GPL version 3, you are granted additional
- permissions described in the GCC Runtime Library Exception, version
- 3.1, as published by the Free Software Foundation.
-
- You should have received a copy of the GNU General Public License and
- a copy of the GCC Runtime Library Exception along with this program;
- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
- <http://www.gnu.org/licenses/>. */
-
-/* This is a Linux specific implementation of a mutex synchronization
- mechanism for libgomp. This type is private to the library. This
- implementation uses atomic instructions and the futex syscall. */
-
-#ifndef GOMP_MUTEX_H
-#define GOMP_MUTEX_H 1
-
-typedef int gomp_mutex_t;
-
-#define GOMP_MUTEX_INIT_0 1
-
-static inline void gomp_mutex_init (gomp_mutex_t *mutex)
-{
- *mutex = 0;
-}
-
-extern void gomp_mutex_lock_slow (gomp_mutex_t *mutex, int);
-static inline void gomp_mutex_lock (gomp_mutex_t *mutex)
-{
- int oldval = __sync_val_compare_and_swap (mutex, 0, 1);
- if (__builtin_expect (oldval, 0))
- gomp_mutex_lock_slow (mutex, oldval);
-}
-
-extern void gomp_mutex_unlock_slow (gomp_mutex_t *mutex);
-
-/* IA64 needs a __sync_synchronize call before __sync_lock_test_and_set
- because __sync_lock_test_and_set is not a full memory fence. */
-static inline void gomp_mutex_unlock (gomp_mutex_t *mutex)
-{
- int val;
- __sync_synchronize ();
- val = __sync_lock_test_and_set (mutex, 0);
- if (__builtin_expect (val > 1, 0))
- gomp_mutex_unlock_slow (mutex);
-}
-
-static inline void gomp_mutex_destroy (gomp_mutex_t *mutex)
-{
-}
-
-#endif /* GOMP_MUTEX_H */
Index: libgomp/config/linux/mips/mutex.h
===================================================================
--- libgomp/config/linux/mips/mutex.h (revision 181718)
+++ libgomp/config/linux/mips/mutex.h (working copy)
@@ -1,27 +0,0 @@
-/* Copyright (C) 2009 Free Software Foundation, Inc.
-
- This file is part of the GNU OpenMP Library (libgomp).
-
- Libgomp is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3, or (at your option)
- any later version.
-
- Libgomp 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 General Public License for
- more details.
-
- Under Section 7 of GPL version 3, you are granted additional
- permissions described in the GCC Runtime Library Exception, version
- 3.1, as published by the Free Software Foundation.
-
- You should have received a copy of the GNU General Public License and
- a copy of the GCC Runtime Library Exception along with this program;
- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
- <http://www.gnu.org/licenses/>. */
-
-/* MIPS needs the same correct usage of __sync_synchronize and
- __sync_lock_test_and_set as ia64. So we just use its mutex.h. */
-
-#include "config/linux/ia64/mutex.h"
--
Alan Modra
Australia Development Lab, IBM
