Initial checkin of GCC 4.9.0 from trunk (r208799).

Change-Id: I48a3c08bb98542aa215912a75f03c0890e497dba

1 files changed, 83 insertions, 0 deletions

diff --git a/gcc-4.9/libgomp/config/linux/sem.c b/gcc-4.9/libgomp/config/linux/sem.c
new file mode 100644
index 000000000..328ba898d
--- /dev/null
+++ b/gcc-4.9/libgomp/config/linux/sem.c
@@ -0,0 +1,83 @@
+/* Copyright (C) 2005-2014 Free Software Foundation, Inc.
+   Contributed by Richard Henderson <rth@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 semaphore synchronization
+   mechanism for libgomp.  This type is private to the library.  This 
+   implementation uses atomic instructions and the futex syscall.  */
+
+#include "wait.h"
+
+void
+gomp_sem_wait_slow (gomp_sem_t *sem, int count)
+{
+  /* First loop spins a while.  */
+  while (count == 0)
+    if (do_spin (sem, 0)
+	/* Spin timeout, nothing changed.  Set waiting flag.  */
+	&& __atomic_compare_exchange_n (sem, &count, SEM_WAIT, false,
+					MEMMODEL_ACQUIRE, MEMMODEL_RELAXED))
+      {
+	futex_wait (sem, SEM_WAIT);
+	count = *sem;
+	break;
+      }
+  /* Something changed.  If it wasn't the wait flag, we're good to go.  */
+    else if (__builtin_expect (((count = *sem) & SEM_WAIT) == 0 && count != 0,
+			       1))
+      {
+	if (__atomic_compare_exchange_n (sem, &count, count - SEM_INC, false,
+					 MEMMODEL_ACQUIRE, MEMMODEL_RELAXED))
+	  return;
+      }
+
+  /* Second loop waits until semaphore is posted.  We always exit this
+     loop with wait flag set, so next post will awaken a thread.  */
+  while (1)
+    {
+      unsigned int wake = count & ~SEM_WAIT;
+      int newval = SEM_WAIT;
+
+      if (wake != 0)
+	newval |= wake - SEM_INC;
+      if (__atomic_compare_exchange_n (sem, &count, newval, false,
+				       MEMMODEL_ACQUIRE, MEMMODEL_RELAXED))
+	{
+	  if (wake != 0)
+	    {
+	      /* If we can wake more threads, do so now.  */
+	      if (wake > SEM_INC)
+		gomp_sem_post_slow (sem);
+	      break;
+	    }
+	  do_wait (sem, SEM_WAIT);
+	  count = *sem;
+	}
+    }
+}
+
+void
+gomp_sem_post_slow (gomp_sem_t *sem)
+{
+  futex_wake (sem, 1);
+}