On Fri, Nov 22, 2019 at 06:32:08PM -0600, Segher Boessenkool wrote:
> On Thu, Nov 14, 2019 at 05:44:42PM -0500, Michael Meissner wrote:
> > This patch generates PADDI to add 34-bit immediate constants on the 'future'
> > system, and prevents such adds from being split.
>
> I don't see that last part? Is that a remnant of a previous version of
> the patch?
This falls out of the add_operand change.
The add splitter is:
;; Split an add that we can't do in one insn into two insns, each of which
;; does one 16-bit part. This is used by combine. Note that the low-order
;; add should be last in case the result gets used in an address.
(define_split
[(set (match_operand:GPR 0 "gpc_reg_operand")
(plus:GPR (match_operand:GPR 1 "gpc_reg_operand")
(match_operand:GPR 2 "non_add_cint_operand")))]
""
[(set (match_dup 0) (plus:GPR (match_dup 1) (match_dup 3)))
(set (match_dup 0) (plus:GPR (match_dup 0) (match_dup 4)))]
{
HOST_WIDE_INT val = INTVAL (operands[2]);
HOST_WIDE_INT low = ((val & 0xffff) ^ 0x8000) - 0x8000;
HOST_WIDE_INT rest = trunc_int_for_mode (val - low, <MODE>mode);
operands[4] = GEN_INT (low);
if (<MODE>mode == SImode || satisfies_constraint_L (GEN_INT (rest)))
operands[3] = GEN_INT (rest);
else if (can_create_pseudo_p ())
{
operands[3] = gen_reg_rtx (DImode);
emit_move_insn (operands[3], operands[2]);
emit_insn (gen_adddi3 (operands[0], operands[1], operands[3]));
DONE;
}
else
FAIL;
})
Since non_add_cint_operand is defined as:
(define_predicate "non_add_cint_operand"
(and (match_code "const_int")
(not (match_operand 0 "add_operand"))))
It follows that if add_operand now allows a 34-bit constant when -mcpu=future,
that non_add_cint_operand will return 0, and the add will not be split.
> > * config/rs6000/predicates.md (add_operand): Add support for
> > PADDI.
>
> More directly: Allow constants that satisfy eI.
Ok.
> > * config/rs6000/rs6000.md (add<mode>3): Add support for PADDI.
>
> (add<mode>3 for GPR): etc.
>
> We have six things all called add<mode>3 (VI2, DDTD, SDI, SFDF, IEEE128,
> VEC_F). Erm.
>
> Wait, this is called *add<mode>3, not add<mode>3.
Yeah, I usually add the iterator part to identify which one was changed.
>
> Okay for trunk with that fixed. Thanks,
>
>
> Segher
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meiss...@linux.ibm.com, phone: +1 (978) 899-4797
