Minor simplify_rtx improvement

[law@redhat.com]

Canonicalizing commutative expressions can result in more recognizable
patterns after simplification.

Bootstrapped on ia32-linux and PA32-hpux.

	* simplify-rtx.c (simplify_rtx): Canonicalize commutative expressions
	by putting complex operands first and constants second.

Index: simplify-rtx.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/simplify-rtx.c,v
retrieving revision 1.61
diff -c -3 -p -r1.61 simplify-rtx.c
*** simplify-rtx.c	2001/06/12 15:25:16	1.61
--- simplify-rtx.c	2001/06/27 23:49:51
*************** simplify_rtx (x)
*** 2520,2527 ****
      case '1':
        return simplify_unary_operation (code, mode,
  				       XEXP (x, 0), GET_MODE (XEXP (x, 0)));
-     case '2':
      case 'c':
        return simplify_binary_operation (code, mode, XEXP (x, 0), XEXP (x, 
1));
  
      case '3':
--- 2520,2545 ----
      case '1':
        return simplify_unary_operation (code, mode,
  				       XEXP (x, 0), GET_MODE (XEXP (x, 0)));
      case 'c':
+       /* Put complex operands first and constants second if commutative.  */
+       if (GET_RTX_CLASS (code) == 'c'
+ 	  && ((CONSTANT_P (XEXP (x, 0)) && GET_CODE (XEXP (x, 1)) != CONST_INT)
+ 	      || (GET_RTX_CLASS (GET_CODE (XEXP (x, 0))) == 'o'
+ 		  && GET_RTX_CLASS (GET_CODE (XEXP (x, 1))) != 'o')
+ 	      || (GET_CODE (XEXP (x, 0)) == SUBREG
+ 		  && GET_RTX_CLASS (GET_CODE (SUBREG_REG (XEXP (x, 0)))) == 'o'
+ 		  && GET_RTX_CLASS (GET_CODE (XEXP (x, 1))) != 'o')))
+ 	{
+ 	  rtx tem;
+ 
+ 	  tem = XEXP (x, 0);
+ 	  XEXP (x, 0) = XEXP (x, 1);
+ 	  XEXP (x, 1) = tem;
+ 	  return simplify_binary_operation (code, mode,
+ 					    XEXP (x, 0), XEXP (x, 1));
+ 	}
+ 
+     case '2':
        return simplify_binary_operation (code, mode, XEXP (x, 0), XEXP (x, 
1));
  
      case '3':