1 files changed, 95 insertions, 0 deletions
diff --git a/libc/nptl/sysdeps/unix/sysv/linux/x86/elision-lock.c b/libc/nptl/sysdeps/unix/sysv/linux/x86/elision-lock.c
new file mode 100644
index 000000000..de16f1b02
--- /dev/null
+++ b/libc/nptl/sysdeps/unix/sysv/linux/x86/elision-lock.c
@@ -0,0 +1,95 @@
+/* elision-lock.c: Elided pthread mutex lock.
+   Copyright (C) 2011-2013 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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 <pthread.h>
+#include "pthreadP.h"
+#include "lowlevellock.h"
+#include "hle.h"
+#include <elision-conf.h>
+
+#if !defined(LLL_LOCK) && !defined(EXTRAARG)
+/* Make sure the configuration code is always linked in for static
+   libraries.  */
+#include "elision-conf.c"
+#endif
+
+#ifndef EXTRAARG
+#define EXTRAARG
+#endif
+#ifndef LLL_LOCK
+#define LLL_LOCK(a,b) lll_lock(a,b), 0
+#endif
+
+#define aconf __elision_aconf
+
+/* Adaptive lock using transactions.
+   By default the lock region is run as a transaction, and when it
+   aborts or the lock is busy the lock adapts itself.  */
+
+int
+__lll_lock_elision (int *futex, short *adapt_count, EXTRAARG int private)
+{
+  if (*adapt_count <= 0)
+    {
+      unsigned status;
+      int try_xbegin;
+
+      for (try_xbegin = aconf.retry_try_xbegin;
+	   try_xbegin > 0;
+	   try_xbegin--)
+	{
+	  if ((status = _xbegin()) == _XBEGIN_STARTED)
+	    {
+	      if (*futex == 0)
+		return 0;
+
+	      /* Lock was busy. Fall back to normal locking.
+		 Could also _xend here but xabort with 0xff code
+		 is more visible in the profiler.  */
+	      _xabort (_ABORT_LOCK_BUSY);
+	    }
+
+	  if (!(status & _XABORT_RETRY))
+	    {
+	      if ((status & _XABORT_EXPLICIT)
+			&& _XABORT_CODE (status) == _ABORT_LOCK_BUSY)
+	        {
+		  /* Right now we skip here. Better would be to wait a bit
+		     and retry. This likely needs some spinning.  */
+		  if (*adapt_count != aconf.skip_lock_busy)
+		    *adapt_count = aconf.skip_lock_busy;
+		}
+	      /* Internal abort. There is no chance for retry.
+		 Use the normal locking and next time use lock.
+		 Be careful to avoid writing to the lock.  */
+	      else if (*adapt_count != aconf.skip_lock_internal_abort)
+		*adapt_count = aconf.skip_lock_internal_abort;
+	      break;
+	    }
+	}
+    }
+  else
+    {
+      /* Use a normal lock until the threshold counter runs out.
+	 Lost updates possible.  */
+      (*adapt_count)--;
+    }
+
+  /* Use a normal lock here.  */
+  return LLL_LOCK ((*futex), private);
+}