Re: i370 port

["Paul Edwards" <mutazilah at gmail dot com>]

> I have a theory that if both displacements in the S-type (ie register plus
> displacement) address are non-zero, that something fails.  So the
> next thing I will do is see if I can detect just that situation, and stop
> it going into the CLC.

I now have that detection in place, and done a self-compile, and all
is looking great.  No idea if that is producing a technically correct
compiler or not though (ie whether my workaround correctly
bypasses all circumstances).

So that leaves 2 more workarounds which I would like to reverse
out.  I'll spend some time on them next.

BFN.  Paul.




;
; cmpmemsi instruction pattern(s).
;

(define_expand "cmpmemsi"
 [(set (match_operand:SI 0 "general_operand" "")
  (compare (match_operand:BLK 1 "general_operand" "")
    (match_operand:BLK 2 "general_operand" "")))
    (use (match_operand:SI 3 "general_operand" ""))
    (use (match_operand:SI 4 "" ""))]
  ""
  "
{
 rtx op1, op2;
 int iv1 = 0;
 int iv2 = 0;

 op1 = XEXP (operands[1], 0);
 if (GET_CODE (op1) == REG
     || (GET_CODE (op1) == PLUS && GET_CODE (XEXP (op1, 0)) == REG
  && GET_CODE (XEXP (op1, 1)) == CONST_INT
  && (unsigned) (iv1 = INTVAL (XEXP (op1, 1))) < 4096))
   {
     op1 = operands[1];
   }
 else
   {
     op1 = gen_rtx_MEM (BLKmode, copy_to_mode_reg (SImode, op1));
   }

 op2 = XEXP (operands[2], 0);
 if (GET_CODE (op2) == REG
     || (GET_CODE (op2) == PLUS && GET_CODE (XEXP (op2, 0)) == REG
  && GET_CODE (XEXP (op2, 1)) == CONST_INT
  && (unsigned) (iv2 = INTVAL (XEXP (op2, 1))) < 4096))
   {
     op2 = operands[2];
   }
 else
   {
     op2 = gen_rtx_MEM (BLKmode, copy_to_mode_reg (SImode, op2));
   }

 /* one circumstance has been found where this short comparison
    causes an internal error. Could be related to the fact that
    both displacements were non-zero, which is unusual. So check
    for that */
 if (((iv1 == 0) || (iv2 == 0)) &&
     GET_CODE (operands[3]) == CONST_INT && INTVAL (operands[3]) < 256)
   {
     emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2,
 gen_rtx_SET (VOIDmode, operands[0],
  gen_rtx_COMPARE (SImode, op1, op2)), /* was VOIDmode */
 gen_rtx_USE (VOIDmode, operands[3]))));
   }
 else
   {
       /* implementation suggested by  Richard Henderson <rth@cygnus.com> 
*/
       rtx reg1 = gen_reg_rtx (DImode);
       rtx reg2 = gen_reg_rtx (DImode);
       rtx result = operands[0];
       rtx mem1 = operands[1];
       rtx mem2 = operands[2];
       rtx len = operands[3];
       if (!CONSTANT_P (len))
         len = force_reg (SImode, len);

       /* Load up the address+length pairs.  */
       emit_insn (gen_rtx_CLOBBER (VOIDmode, reg1));
       emit_move_insn (gen_rtx_SUBREG (SImode, reg1, 0),
                       force_operand (XEXP (mem1, 0), NULL_RTX));
       emit_move_insn (gen_rtx_SUBREG (SImode, reg1, GET_MODE_SIZE 
(SImode)), len);

       emit_insn (gen_rtx_CLOBBER (VOIDmode, reg2));
       emit_move_insn (gen_rtx_SUBREG (SImode, reg2, 0),
                       force_operand (XEXP (mem2, 0), NULL_RTX));
       emit_move_insn (gen_rtx_SUBREG (SImode, reg2, GET_MODE_SIZE 
(SImode)), len);

       /* Compare! */
       emit_insn (gen_cmpmemsi_1 (result, reg1, reg2));
   }
 DONE;
}")

; Compare a block that is less than 256 bytes in length.

(define_insn ""
 [(set (match_operand:SI 0 "register_operand" "=d")
(compare:SI (match_operand:BLK 1 "s_operand" "m")
  (match_operand:BLK 2 "s_operand" "m")))
  (use (match_operand:QI 3 "immediate_operand" "I"))]
 "((unsigned) INTVAL (operands[3]) < 256)"
 "*
{
 check_label_emit ();
 mvs_check_page (0, 22, 0);
 return \"CLC %O1(%c3,%R1),%2\;BH *+12\;BL *+6\;SLR %0,%0\;LNR %0,%0\";
}"
  [(set_attr "length" "22")]
)

; Compare a block that is larger than 255 bytes in length.
;        (mem:BLK (subreg:SI (match_operand:DI 1 "register_operand" "+d") 
0))
;        (mem:BLK (subreg:SI (match_operand:DI 2 "register_operand" "+d") 
0))))

(define_insn "cmpmemsi_1"
 [(set (match_operand:SI 0 "register_operand" "+d")
       (compare:SI
       (mem:BLK (match_operand:DI 1 "register_operand" "+d") )
       (mem:BLK (match_operand:DI 2 "register_operand" "+d") )))
  (use (match_dup 1))
  (use (match_dup 2))
  (clobber (match_dup 1))
  (clobber (match_dup 2))]
 ""
 "*
{
 check_label_emit ();
 mvs_check_page (0, 18, 0);
 return \"LA %0,1(0,0)\;CLCL %1,%2\;BH *+12\;BL *+6\;SLR %0,%0\;LNR 
%0,%0\";
}"
  [(set_attr "length" "18")]
)