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Re: Patch for PR libgomp/37938, IA64 specific.
On Thu, Nov 06, 2008 at 01:09:44PM -0800, H.J. Lu wrote:
> According to ia64 psABI, ia64 _sync_bool_compare_and_swap should
> have full barrier. __sync_lock_test_and_set has acquire barrier.
Ok, then we have just one problematic __sync_lock_test_and_set
in whole libgomp.
Would the following (untested) patch cure it? Or we can use
__sync_synchronize (); val = __sync_lock_test_and_set (mutex, 0);
if we don't mind mf + xchg4.acq.
--- libgomp/config/linux/ia64/mutex.h.jj 2008-11-06 22:19:11.000000000 +0100
+++ libgomp/config/linux/ia64/mutex.h 2008-11-06 22:22:11.000000000 +0100
@@ -0,0 +1,66 @@
+/* Copyright (C) 2005, 2008 Free Software Foundation, Inc.
+ Contributed by Richard Henderson <email@example.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 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.
+ 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 Lesser General Public License for
+ more details.
+ You should have received a copy of the GNU Lesser General Public License
+ along with libgomp; see the file COPYING.LIB. If not, write to the
+ Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ MA 02110-1301, USA. */
+/* As a special exception, if you link this library with other files, some
+ of which are compiled with GCC, to produce an executable, this library
+ does not by itself cause the resulting executable to be covered by the
+ GNU General Public License. This exception does not however invalidate
+ any other reasons why the executable file might be covered by the GNU
+ General Public License. */
+/* 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. */
+#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);
+static inline void gomp_mutex_lock (gomp_mutex_t *mutex)
+ if (!__sync_bool_compare_and_swap (mutex, 0, 1))
+ gomp_mutex_lock_slow (mutex);
+extern void gomp_mutex_unlock_slow (gomp_mutex_t *mutex);
+static inline void gomp_mutex_unlock (gomp_mutex_t *mutex)
+ /* On ia64, __sync_lock_test_and_set has acquire semantics,
+ while release semantics is needed for gomp_mutex_unlock. */
+ int val;
+ __asm__ __volatile__ ("xchg4.rel %0 = [%1], r0;;"
+ : "=r" (val) : "r" (mutex) : "memory");
+ 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 */