expr.c (expand_assignment): Optimize away no-op moves where the source and…

expr.c (expand_assignment): Optimize away no-op moves where the source and destination are equal and have...


	* expr.c (expand_assignment): Optimize away no-op moves where the
	source and destination are equal and have no side-effects.

From-SVN: r113009

gcc/ChangeLog

+2006-04-17  Roger Sayle  <roger@eyesopen.com>
+
+	* expr.c (expand_assignment): Optimize away no-op moves where the
+	source and destination are equal and have no side-effects.
+
 2006-04-17  Richard Guenther  <rguenther@suse.de>
 
 	PR target/26826

gcc/expr.c

@@ -3988,13 +3988,16 @@ expand_assignment (tree to, tree from)
   rtx result;
 
   /* Don't crash if the lhs of the assignment was erroneous.  */
-
   if (TREE_CODE (to) == ERROR_MARK)
     {
       result = expand_normal (from);
       return;
     }
 
+  /* Optimize away no-op moves without side-effects.  */
+  if (operand_equal_p (to, from, 0))
+    return;
+
   /* Assignment of a structure component needs special treatment
      if the structure component's rtx is not simply a MEM.
      Assignment of an array element at a constant index, and assignment of