fix loop unrolling

[Jan Hubicka]

> On Tue, Jan 22, 2002 at 12:04:34PM +0100, Jan Hubicka wrote:
> > It consists of addition of two thinks fetched directly from insn chain,
> > so they should be nonmemory_operand already.
> > 
> > Would be that ok with adding copy_rtx everywhere?
> 
> If we don't have memories, then we don't need copy_rtx anywhere.
OK, I see that the final_value comes from rtx stream and we still can
theoretically have memories if something nasty happends to prevent invariant
code motion from being active - it has cost scheme to prevent action in some
cases.

Is this variant OK?

Thu Jan 24 21:33:40 CET 2002  Jan Hubicka  <jh@suse.cz>
	* unroll.c (unroll_loop): Lower final_value to nonmemory operand;
	avoid it's copies.
*** /home/hubicka/egcs2/egcs/gcc/unroll.c	Tue Jan 15 00:58:20 2002
--- unroll.c	Thu Jan 24 21:33:25 2002
*************** unroll_loop (loop, insn_count, strength_
*** 930,935 ****
--- 930,948 ----
  
  	  start_sequence ();
  
+ 	  /* Final value may have form of (PLUS val1 const1_rtx).  We need
+ 	     to convert it into general operand, so compute the real value.  */
+ 
+ 	  if (GET_CODE (final_value) == PLUS)
+ 	    {
+ 	      final_value = expand_simple_binop (mode, PLUS,
+ 						 copy_rtx (XEXP (final_value, 0)),
+ 						 copy_rtx (XEXP (final_value, 1)),
+ 						 NULL_RTX, 0, OPTAB_LIB_WIDEN);
+ 	    }
+ 	  if (!nonmemory_operand (final_value, VOIDmode))
+ 	    final_value = force_reg (mode, copy_rtx (final_value));
+ 
  	  /* Calculate the difference between the final and initial values.
  	     Final value may be a (plus (reg x) (const_int 1)) rtx.
  	     Let the following cse pass simplify this if initial value is
*************** unroll_loop (loop, insn_count, strength_
*** 949,955 ****
  	     so we can pretend that the overflow value is 0/~0.  */
  
  	  if (cc == NE || less_p != neg_inc)
! 	    diff = expand_simple_binop (mode, MINUS, copy_rtx (final_value),
  					copy_rtx (initial_value), NULL_RTX, 0,
  					OPTAB_LIB_WIDEN);
  	  else
--- 962,968 ----
  	     so we can pretend that the overflow value is 0/~0.  */
  
  	  if (cc == NE || less_p != neg_inc)
! 	    diff = expand_simple_binop (mode, MINUS, final_value,
  					copy_rtx (initial_value), NULL_RTX, 0,
  					OPTAB_LIB_WIDEN);
  	  else