expr.c (expand_expr, [...]): Do not call copy_to_reg with VOIDmode operand.

	* expr.c (expand_expr, case NE_EXPR): Do not call copy_to_reg with
	VOIDmode operand.  Add compile-time optimization for constant results.

From-SVN: r50734

gcc/ChangeLog

+2002-03-13  Ulrich Weigand  <uweigand@de.ibm.com>
+
+	* expr.c (expand_expr, case NE_EXPR): Do not call copy_to_reg with
+	VOIDmode operand.  Add compile-time optimization for constant results.
+
 2002-03-12  Jason Merrill  <jason@redhat.com>
 
 	* c-typeck.c (convert_for_assignment): Don't allow conversions

gcc/expr.c

@@ -7944,8 +7944,25 @@ expand_expr (exp, target, tmode, modifier)
 	  temp = expand_expr (TREE_OPERAND (exp, 0), original_target,
 			      VOIDmode, 0);
 
+	  /* If temp is constant, we can just compute the result.  */
+	  if (GET_CODE (temp) == CONST_INT)
+	    {
+	      if (INTVAL (temp) != 0)
+	        emit_move_insn (target, const1_rtx);
+	      else
+	        emit_move_insn (target, const0_rtx);
+
+	      return target;
+	    }
+
 	  if (temp != original_target)
-	    temp = copy_to_reg (temp);
+	    {
+	      enum machine_mode mode1 = GET_MODE (temp);
+	      if (mode1 == VOIDmode)
+		mode1 = tmode != VOIDmode ? tmode : mode;
+	      
+	      temp = copy_to_mode_reg (mode1, temp);
+	    }
 
 	  op1 = gen_label_rtx ();
 	  emit_cmp_and_jump_insns (temp, const0_rtx, EQ, NULL_RTX,