1 files changed, 76 insertions, 0 deletions
diff --git a/libitm/config/generic/tls.cc b/libitm/config/generic/tls.cc
new file mode 100644
index 00000000000..3e82cff0902
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+++ b/libitm/config/generic/tls.cc
@@ -0,0 +1,76 @@
+/* Copyright (C) 2010, 2011 Free Software Foundation, Inc.
+   Contributed by Richard Henderson <rth@redhat.com>.
+
+   This file is part of the GNU Transactional Memory Library (libitm).
+
+   Libitm 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 of the License, or
+   (at your option) any later version.
+
+   Libitm 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/>.  */
+
+#include "libitm_i.h"
+
+namespace GTM HIDDEN {
+
+// Filter out any updates that overlap the libitm stack, as defined by
+// TOP (entry point to library) and BOT (below current function).  This
+// definition should be fine for all stack-grows-down architectures.
+
+gtm_cacheline_mask __attribute__((noinline))
+gtm_mask_stack(gtm_cacheline *line, gtm_cacheline_mask mask)
+{
+  void *top = gtm_thr()->jb.cfa;
+  void *bot = __builtin_dwarf_cfa();
+
+  // We must have come through an entry point that set TOP.
+  assert (top != NULL);
+
+  if (line + 1 < bot)
+    {
+      // Since we don't have the REAL stack boundaries for this thread,
+      // we cannot know if this is a dead write to a stack address below
+      // the current function or if it is write to another VMA.  In either
+      // case allowing the write should not affect correctness.
+    }
+  else if (line >= top)
+    {
+      // A valid write to an address in an outer stack frame, or a write
+      // to another VMA.
+    }
+  else
+    {
+      uintptr_t diff = (uintptr_t)top - (uintptr_t)line;
+      if (diff >= CACHELINE_SIZE)
+	{
+	  // The write is either fully within the proscribed area, or the tail
+	  // of the cacheline overlaps the proscribed area.  Assume that all
+	  // stacks are at least cacheline aligned and declare the head of the
+	  // cacheline dead.
+	  mask = 0;
+	}
+      else
+	{
+	  // The head of the cacheline is within the proscribed area, but the
+	  // tail of the cacheline is live.  Eliminate the dead writes.
+	  mask &= (gtm_cacheline_mask)-1 << diff;
+	}
+    }
+
+  return mask;
+}
+
+} // namespace GTM