libcall problem during new unroller merge

[Jan Hubicka]

> Hello,
> > > (insn 547 546 548 (nil) (set (reg:SI 238)
> > >         (reg:SI 0 eax)) -1 (nil)
> > >     (insn_list:REG_RETVAL 543 (expr_list:REG_EQUAL (expr_list (use (mem:BLK (scratch) [0 A8]))
> > >                 (expr_list (symbol_ref:SI ("strcmp"))
> > >                     (expr_list (mem/f:SI (symbol_ref:SI ("ix86_cpu_string")) [9 ix86_cpu_string+0 S4 A32])
> > >                         (expr_list (mem/s/u:SI (plus:SI (reg:SI 235)
> > >                                     (reg:SI 231)) [9 <variable>.name+0 S4 A32])
> > >                             (nil)))))
> > >             (nil))))
> 
> one question to this -- what does the expr_list inside REG_EQUAL mean?

It is just place holder - we don't have RTL construct to represent call
with arguments, so we present it as linked list of expression.  Function
is first, arguments follows
> >From the documentation I've got feeling that there should be rtl
> expression of value of libcall; is this some way to express that this
> is call to function with those arguments that is not documented?
> Anyway, it makes delete_trivially_dead_insns wrong, as it does not
> find register usage in this REG_EQUAL note.

THis looks like the problem.  Now I see, delte_trivially_dead_insns
ignores body of expr_list.
DOes this patch fix the problem?

Index: cse.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cse.c,v
retrieving revision 1.253
diff -c -3 -p -r1.253 cse.c
*** cse.c	28 Jan 2003 21:29:40 -0000	1.253
--- cse.c	7 Feb 2003 15:40:08 -0000
*************** count_reg_usage (x, counts, dest, incr)
*** 7461,7466 ****
--- 7461,7467 ----
       int incr;
  {
    enum rtx_code code;
+   rtx note;
    const char *fmt;
    int i, j;
  
*************** count_reg_usage (x, counts, dest, incr)
*** 7518,7533 ****
        /* Things used in a REG_EQUAL note aren't dead since loop may try to
  	 use them.  */
  
!       count_reg_usage (REG_NOTES (x), counts, NULL_RTX, incr);
        return;
  
-     case EXPR_LIST:
      case INSN_LIST:
!       if (REG_NOTE_KIND (x) == REG_EQUAL
! 	  || (REG_NOTE_KIND (x) != REG_NONNEG && GET_CODE (XEXP (x,0)) == USE))
! 	count_reg_usage (XEXP (x, 0), counts, NULL_RTX, incr);
!       count_reg_usage (XEXP (x, 1), counts, NULL_RTX, incr);
!       return;
  
      default:
        break;
--- 7519,7531 ----
        /* Things used in a REG_EQUAL note aren't dead since loop may try to
  	 use them.  */
  
!       note = find_reg_equal_equiv_note (x);
!       if (note)
!         count_reg_usage (XEXP (note, 0), counts, NULL_RTX, incr);
        return;
  
      case INSN_LIST:
!       abort ();
  
      default:
        break;