Re: i370 port

[Ulrich Weigand]

Paul Edwards wrote:

> int
> i370_branch_dest (branch)
>      rtx branch;
> {
>   rtx dest = SET_SRC (PATTERN (branch));
>   int dest_uid;
>   int dest_addr;
> 
>   /* first, compute the estimated address of the branch target */
>   if (GET_CODE (dest) == IF_THEN_ELSE)
>     dest = XEXP (dest, 1);
>   dest = XEXP (dest, 0);

This is set up only to handle direct branches of the form

  (set (pc) (label_ref ...))

and indirect branches of the form

  (set (pc) (if_then_else (...) (label_ref ...) (pc)))

but *not* indirect branches of the form

  (set (pc) (if_then_else (...) (pc) (label_ref ...)))

This latter form is accepted by the "negated conditional
jump instructions in the i370.md file, like so:

(define_insn ""
  [(set (pc)
        (if_then_else (eq (cc0)
                          (const_int 0))
                      (pc)
                      (label_ref (match_operand 0 "" ""))))
;   (clobber (reg:SI 14))
   ]
  ""
  "*
{
  check_label_emit ();
  mvs_check_page (0, 4, 0);
  if (i370_short_branch(insn) || mvs_check_label (CODE_LABEL_NUMBER 
(operands[0])))
    {


Therefore, the i370_branch_dest routine needs to handle
those as well.  Probably something along the following lines:

  if (GET_CODE (dest) == IF_THEN_ELSE)
    {
      if (GET_CODE (XEXP (dest, 1) == LABEL_REF)
        dest = XEXP (dest, 1);
      else
        dest = XEXP (dest, 2);
    }

  gcc_assert (GET_CODE (dest) == LABEL_REF);
  dest = XEXP (dest, 0);

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  ulrich.weig...@de.ibm.com