re PR debug/49496 (-fcompare-debug failure (length) with -O -ftree-vectorize)

	PR debug/49496
	* tree-vect-patterns.c (vect_recog_widen_mult_pattern): Ignore debug
	uses.

	* gcc.dg/pr49496.c: New test.

From-SVN: r175314

gcc/ChangeLog

+2011-06-22  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/49496
+	* tree-vect-patterns.c (vect_recog_widen_mult_pattern): Ignore debug
+	uses.
+
 2011-06-22  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/49493

gcc/testsuite/ChangeLog

+2011-06-22  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/49496
+	* gcc.dg/pr49496.c: New test.
+
 2011-06-22  Janis Johnson  <janisjo@codesourcery.com>
 
 	* gcc.target/arm/scd42-3.c: Allow -march-xscale; skip if -mcpu

gcc/testsuite/gcc.dg/pr49496.c

+/* PR debug/49496 */
+/* { dg-do compile } */
+/* { dg-options "-O3 -fcompare-debug" } */
+
+unsigned short u[8], s1[8], s2[8];
+
+void bar (unsigned short *);
+
+void
+foo (void)
+{
+  unsigned short e[8];
+  int i;
+  for (i = 0; i < 8; i++)
+    {
+      int tmp = s1[i] * s2[i];
+      e[i] = (tmp & 0xffff0000) >> 16;
+    }
+  bar (e);
+}

gcc/tree-vect-patterns.c

 /* Analysis Utilities for Loop Vectorization.
-   Copyright (C) 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
+   Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011
+   Free Software Foundation, Inc.
    Contributed by Dorit Nuzman <dorit@il.ibm.com>
 
 This file is part of GCC.
@@ -557,6 +558,8 @@ vect_recog_widen_mult_pattern (VEC (gimple, heap) **stmts,
 
       FOR_EACH_IMM_USE_FAST (use_p, imm_iter, lhs)
         {
+	  if (is_gimple_debug (USE_STMT (use_p)))
+	    continue;
           use_stmt = USE_STMT (use_p);
           nuses++;
         }