1 files changed, 109 insertions, 0 deletions
diff --git a/libcilkrts/runtime/spin_mutex.c b/libcilkrts/runtime/spin_mutex.c
new file mode 100644
index 00000000000..03908f26322
--- /dev/null
+++ b/libcilkrts/runtime/spin_mutex.c
@@ -0,0 +1,109 @@
+/* spin_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 "spin_mutex.h"
+#include "bug.h"
+#include "os.h"
+#include "stats.h"
+
+// TBD (11/30/12): We should be doing a conditional test-xchg instead
+// of an unconditional xchg operation for the spin mutex.
+
+/* 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
+
+
+spin_mutex* spin_mutex_create() 
+{
+    spin_mutex* mutex = (spin_mutex*)__cilkrts_malloc(sizeof(spin_mutex));
+    spin_mutex_init(mutex);
+    return mutex;
+}
+
+void spin_mutex_init(struct spin_mutex *m)
+{
+    // 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 spin_mutex_lock(struct spin_mutex *m)
+{
+    int count;
+    const int maxspin = 1000; /* SWAG */
+    if (!TRY_ACQUIRE(m)) {
+        count = 0;
+        do {
+            do {
+                __cilkrts_short_pause();
+                if (++count >= maxspin) {
+                    /* let the OS reschedule every once in a while */
+                    __cilkrts_yield();
+                    count = 0;
+                }
+            } while (m->lock != 0);
+        } while (!TRY_ACQUIRE(m));
+    }
+}
+
+int spin_mutex_trylock(struct spin_mutex *m)
+{
+    return TRY_ACQUIRE(m);
+}
+
+void spin_mutex_unlock(struct spin_mutex *m)
+{
+    RELEASE(m);
+}
+
+void spin_mutex_destroy(struct spin_mutex *m)
+{
+    __cilkrts_free(m);
+}
+
+/* End spin_mutex.c */