Re: adding movz to machine description

["Petar Bajic" <petar dot bajic at micronasnit dot com>]

I finally made it work, these rules will successfully emit both movz and 
movn instructions.
Thank you for help.

(define_insn "movsicc_movz"
 [(set (match_operand:SI 0 "register_operand" "=d")
  (if_then_else:SI (eq (match_operand:SI 1 "register_operand" 
"d")(const_int 0))
   (match_operand:SI 2 "register_operand" "d")
   (match_dup 0) ))]
 ""
 "movz\\t%0,%2,%1"
 [(set_attr "type" "condmove")
  (set_attr "mode" "SI")])

(define_insn "movsicc_movn"
 [(set (match_operand:SI 0 "register_operand" "=d")
  (if_then_else:SI (ne (match_operand:SI 1 "register_operand" 
"d")(const_int 0))
   (match_operand:SI 2 "register_operand" "d")
   (match_dup 0) ))]
 ""
 "movn\\t%0,%2,%1"
 [(set_attr "type" "condmove")
  (set_attr "mode" "SI")])



(define_expand "movsicc"
   [(set (match_operand:SI 0 "register_operand" "=d")
    (if_then_else:SI
      (match_operator 1 "comparison_operator" [(match_operand:SI 4 
"register_operand" "d") (const_int 0)])
       (match_operand:SI 2 "register_operand" "d")
(match_operand:SI 3 "register_operand" "d") ))]
 ""
 "
{
if (operands[2] != operands[0])
{
emit_insn (gen_movsi (operands[0], operands[3]));
if (GET_CODE(operands[1]) == EQ)
{
   dlx_emit_cond_move_z(operands[0], operands[2], operands[3]);
   DONE;
  }
  else if (GET_CODE(operands[1]) == NE)
  {
   dlx_emit_cond_move_n(operands[0], operands[2], operands[3]);
   DONE;
  }
  else
   FAIL;
}
else
{
if (GET_CODE(operands[1]) == NE)
{
   dlx_emit_cond_move_z(operands[0], operands[3], operands[3]);
   DONE;
  }
  else if (GET_CODE(operands[1]) == EQ)
  {
   dlx_emit_cond_move_n(operands[0], operands[3], operands[3]);
   DONE;
  }
  else
   FAIL;
}
}")


(define_insn "movsicc_internal"
 [(set (match_operand:SI 0 "register_operand" "=j,j,j,j,j")
 (if_then_else:SI
 (match_operator 1 "comparison_operator" [(match_operand:SI 4 
"register_operand" "k,k,k,k,k") (const_int 0)])
 (match_operand:SI 2 "register_operand" "d,i,d,I,d")
 (match_operand:SI 3 "register_operand" "d,d,i,d,I")))]
 "(GET_CODE(operands[1]) == EQ)"
 "movz\\t%0,%2,%4\\n\\tmovn\\t%0,%3,%4"
 [(set_attr "type" "condmove")
  (set_attr "length" "2")
  (set_attr "mode" "SI")])


And in dlx.c functions dlx_emit_cond_move_n and dlx_emit_cond_move_z look 
like this:

int

dlx_emit_cond_move_z (rtx dest, rtx src1, rtx src2)

{

dlx_compare_op0 = force_reg(SImode, dlx_compare_op0);

emit_insn(gen_movsicc_movz(dest, dlx_compare_op0, src1));

}

int

dlx_emit_cond_move_n (rtx dest, rtx src1, rtx src2)

{

dlx_compare_op0 = force_reg(SImode, dlx_compare_op0);

emit_insn(gen_movsicc_movn(dest, dlx_compare_op0, src1));

}

best regards,
Petar Bajic

----- Original Message ----- 
From: "Ian Lance Taylor" <iant@google.com>
To: "Petar Bajic" <petar.bajic@micronasnit.com>
Cc: <gcc-help@gcc.gnu.org>
Sent: Tuesday, July 25, 2006 3:39 PM
Subject: Re: adding movz to machine description


> "Petar Bajic" <petar.bajic@micronasnit.com> writes:
>
> > > It may be correct for the pattern to not be matched with expand.  It's
> > > OK if the if-conversion pass picks it up, which seems to be what is
> > > happening for you.
> > >
> > > If the generated code you are getting is wrong, then problem is likely
> > > in the define_insn patterns somewhere.  They don't correct represent
> > > what the instruction does, or they don't correctly implement it.
> > >
> > > Ian
> >
> > After some modifications, I managed to make gcc use my define_expand -
> > I see it in debug.11.ce1 and following files, but then it disapears in
> > debug.17.combine, and in the end it does not appear in asm code. How
> > to find out what kills it? :)
>
> That means that the combine pass has replaced it with something else
> which is equivalent which the combine pass thought would be cheaper.
> Look at the generated RTL to see what it turned into.  If the
> resulting code is less efficient to run, then you need to adjust your
> costs (the TARGET_RTX_COSTS hook).
>
> Ian