tree-ssa-math-opts.c (convert_mult_to_widen): Check actual precision against gimple constraints.

2012-03-07  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-math-opts.c (convert_mult_to_widen): Check actual
	precision against gimple constraints.

From-SVN: r185026

gcc/ChangeLog

+2012-03-07  Richard Guenther  <rguenther@suse.de>
+
+	* tree-ssa-math-opts.c (convert_mult_to_widen): Check actual
+	precision against gimple constraints.
+
 2012-03-06  Richard Sandiford  <rdsandiford@googlemail.com>
 
 	PR middle-end/52372

gcc/tree-ssa-math-opts.c

@@ -2158,6 +2158,8 @@ convert_mult_to_widen (gimple stmt, gimple_stmt_iterator *gsi)
   /* Ensure that the inputs to the handler are in the correct precison
      for the opcode.  This will be the full mode size.  */
   actual_precision = GET_MODE_PRECISION (actual_mode);
+  if (2 * actual_precision > TYPE_PRECISION (type))
+    return false;
   if (actual_precision != TYPE_PRECISION (type1)
       || from_unsigned1 != TYPE_UNSIGNED (type1))
     {