2012-08-02 Richard Guenther <rguenther@suse.de>

	PR tree-optimization/50672
	Revert
	2012-08-01  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-tail-merge.c (release_last_vdef): Remove.
	(replace_block_by): Adjust.

	* g++.dg/torture/pr50672.C: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@190070 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 32 insertions, 0 deletions

diff --git a/gcc/tree-ssa-tail-merge.c b/gcc/tree-ssa-tail-merge.c
index ab37336d0c4..a2d4633e993 100644
--- a/gcc/tree-ssa-tail-merge.c
+++ b/gcc/tree-ssa-tail-merge.c
@@ -812,6 +812,37 @@ same_succ_flush_bbs (bitmap bbs)
     same_succ_flush_bb (BASIC_BLOCK (i));
 }
 
+/* Release the last vdef in BB, either normal or phi result.  */
+
+static void
+release_last_vdef (basic_block bb)
+{
+  gimple_stmt_iterator i;
+
+  for (i = gsi_last_bb (bb); !gsi_end_p (i); gsi_prev_nondebug (&i))
+    {
+      gimple stmt = gsi_stmt (i);
+      if (gimple_vdef (stmt) == NULL_TREE)
+	continue;
+
+      mark_virtual_operand_for_renaming (gimple_vdef (stmt));
+      return;
+    }
+
+  for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i))
+    {
+      gimple phi = gsi_stmt (i);
+      tree res = gimple_phi_result (phi);
+
+      if (is_gimple_reg (res))
+	continue;
+
+      mark_virtual_phi_result_for_renaming (phi);
+      return;
+    }
+  
+}
+
 /* For deleted_bb_preds, find bbs with same successors.  */
 
 static void
@@ -1446,6 +1477,7 @@ replace_block_by (basic_block bb1, basic_block bb2)
   bb1->frequency = 0;
 
   /* Do updates that use bb1, before deleting bb1.  */
+  release_last_vdef (bb1);
   same_succ_flush_bb (bb1);
 
   delete_basic_block (bb1);