1 files changed, 56 insertions, 0 deletions
diff --git a/ports/sysdeps/tile/nptl/pthread_spin_lock.c b/ports/sysdeps/tile/nptl/pthread_spin_lock.c
new file mode 100644
index 0000000000..18716f44c9
--- /dev/null
+++ b/ports/sysdeps/tile/nptl/pthread_spin_lock.c
@@ -0,0 +1,56 @@
+/* Copyright (C) 2011 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
+
+   The GNU C Library 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.
+
+   The GNU C Library 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 the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include "pthreadP.h"
+#include <arch/spr_def.h>
+#include <atomic.h>
+
+/* Bound point for bounded exponential backoff */
+#define BACKOFF_MAX 2048
+
+/* Initial cycle delay for exponential backoff */
+#define BACKOFF_START 32
+
+#ifdef __tilegx__
+/* Use cmpexch() after the initial fast-path exch to avoid
+   invalidating the cache line of the lock holder.  */
+# define TNS(p) atomic_exchange_acq((p), 1)
+# define CMPTNS(p) atomic_compare_and_exchange_val_acq((p), 1, 0)
+#else
+# define TNS(p) __insn_tns(p)
+# define CMPTNS(p) __insn_tns(p)
+# define SPR_CYCLE SPR_CYCLE_LOW   /* The low 32 bits are sufficient. */
+#endif
+
+int
+pthread_spin_lock (pthread_spinlock_t *lock)
+{
+  if (__builtin_expect (TNS (lock) != 0, 0))
+    {
+      unsigned int backoff = BACKOFF_START;
+      while (CMPTNS (lock) != 0)
+        {
+          unsigned int start = __insn_mfspr (SPR_CYCLE);
+          while (__insn_mfspr (SPR_CYCLE) - start < backoff)
+            ;
+          if (backoff < BACKOFF_MAX)
+            backoff *= 2;
+        }
+    }
+  return 0;
+}