re PR tree-optimization/15991 (phi nodes with identical arguments still remain at t50.tailc)

	PR tree-optimization/15991
	* tree-cfg.c (tree_block_label): Export.
	* tree-flow-inline.h (bsi_after_labels): New function.
	* tree-flow.h (bsi_after_labels, tree_block_label): Declare.
	* tree-ssa.c (propagate_into_addr): New function.
	(replace_immediate_uses): Handle propagation of pointer constants.
	(raise_value): Do not restrict propagation of pointer constants.
	* tree-ssanames.c (duplicate_ssa_name): New function.
	* tree.h (duplicate_ssa_name): Declare.

From-SVN: r83297

1 files changed, 47 insertions, 0 deletions

diff --git a/gcc/tree-flow-inline.h b/gcc/tree-flow-inline.h
index 4fe44ef..c47ba09 100644
--- a/gcc/tree-flow-inline.h
+++ b/gcc/tree-flow-inline.h
@@ -629,6 +629,53 @@ bsi_start (basic_block bb)
   return bsi;
 }
 
+/* Return a block statement iterator that points to the last label in
+   block BB.  */
+
+static inline block_stmt_iterator
+bsi_after_labels (basic_block bb)
+{
+  block_stmt_iterator bsi;
+  tree_stmt_iterator next;
+
+  bsi.bb = bb;
+
+  if (!bb->stmt_list)
+    {
+#ifdef ENABLE_CHECKING
+      if (bb->index >= 0)
+	abort ();
+#endif
+      bsi.tsi.ptr = NULL;
+      bsi.tsi.container = NULL;
+      return bsi;
+    }
+
+  bsi.tsi = tsi_start (bb->stmt_list);
+  if (tsi_end_p (bsi.tsi))
+    return bsi;
+
+  /* Ensure that there are some labels.  The rationale is that we want
+     to insert after the bsi that is returned, and these insertions should
+     be placed at the start of the basic block.  This would not work if the
+     first statement was not label; rather fail here than enable the user
+     proceed in wrong way.  */
+  if (TREE_CODE (tsi_stmt (bsi.tsi)) != LABEL_EXPR)
+    abort ();
+
+  next = bsi.tsi;
+  tsi_next (&next);
+
+  while (!tsi_end_p (next)
+	 && TREE_CODE (tsi_stmt (next)) == LABEL_EXPR)
+    {
+      bsi.tsi = next;
+      tsi_next (&next);
+    }
+
+  return bsi;
+}
+
 /* Return a block statement iterator that points to the end of basic
    block BB.  */
 static inline block_stmt_iterator