re PR tree-optimization/87889 (CPU2000 177.mesa failed to build)

2018-11-06  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/87889
	* tree-vect-loop-manip.c (slpeel_duplicate_current_defs_from_edges):
	Do nothing if old and new arg are the same

	* gcc.dg/pr87894.c: New testcase.

From-SVN: r265833

gcc/ChangeLog

+2018-11-06  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/87889
+	* tree-vect-loop-manip.c (slpeel_duplicate_current_defs_from_edges):
+	Do nothing if old and new arg are the same
+
 2018-11-06  Andreas Krebbel  <krebbel@linux.ibm.com>
 
 	PR target/87723

gcc/testsuite/ChangeLog

+2018-11-06  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/87889
+	* gcc.dg/pr87894.c: New testcase.
+
 2018-11-06  Andreas Krebbel  <krebbel@linux.ibm.com>
 
 	PR target/87723

gcc/testsuite/gcc.dg/pr87894.c

+/* { dg-do compile } */
+/* { dg-options "-Ofast" } */
+
+int a, b, c, d;
+double e;
+
+void f(double g[][1])
+{
+  for (;;)
+    {
+      double h;
+      for (; b < c; b++)
+	{
+	  if (b >= 0)
+	    ;
+	  else if (d)
+	    h = 2.0;
+	  else
+	    h = 0.0;
+	  if (e)
+	    g[a][b] = 0.0;
+	  g[a][b] = h;
+	}
+    }
+}
+

gcc/tree-vect-loop-manip.c

@@ -977,7 +977,8 @@ slpeel_duplicate_current_defs_from_edges (edge from, edge to)
 	}
       if (TREE_CODE (from_arg) != SSA_NAME)
 	gcc_assert (operand_equal_p (from_arg, to_arg, 0));
-      else if (TREE_CODE (to_arg) == SSA_NAME)
+      else if (TREE_CODE (to_arg) == SSA_NAME
+	       && from_arg != to_arg)
 	{
 	  if (get_current_def (to_arg) == NULL_TREE)
 	    {