Gently ping for this :)
Hi Richard, Is it OK to adopt the ccmp change? Or did you know who can
help to review this part?
Thanks.
Hongyu Wang <wwwhhhyyy...@gmail.com> 于2024年5月15日周三 16:25写道：
>
> CC'd Richard for ccmp part as previously it is added only for aarch64.
> The original logic will not interrupted since if
> aarch64_gen_ccmp_first succeeded, aarch64_gen_ccmp_next will also
> success, the cmp/fcmp and ccmp/fccmp supports all GPI/GPF, and the
> prepare_operand will fixup the input that cmp supports but ccmp not,
> so ret/ret2 will all be valid when comparing cost.
> Thanks in advance.
>
> Hongyu Wang <hongyu.w...@intel.com> 于2024年5月15日周三 16:22写道：
> >
> > For general ccmp scenario, the tree sequence is like
> >
> > _1 = (a < b)
> > _2 = (c < d)
> > _3 = _1 & _2
> >
> > current ccmp expanding will try to swap compare order for _1 and _2,
> > compare the cost/cost2 between compare _1 and _2 first, then return the
> > sequence with lower cost.
> >
> > For x86 ccmp, we don't support FP compare as ccmp operand, but we
> > support fp comi + int ccmp sequence. With current cost comparison
> > model, the fp comi + int ccmp can never be generated since it doesn't
> > check whether expand_ccmp_next returns available result and the rtl
> > cost for the empty ccmp sequence is always smaller.
> >
> > Check the expand_ccmp_next result ret and ret2, returns the valid one
> > before cost comparison.
> >
> > gcc/ChangeLog:
> >
> > * ccmp.cc (expand_ccmp_expr_1): Check ret and ret2 of
> > expand_ccmp_next, returns the valid one first before
> > comparing cost.
> > ---
> > gcc/ccmp.cc | 12 +++++++++++-
> > 1 file changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/gcc/ccmp.cc b/gcc/ccmp.cc
> > index 7cb525addf4..4b424220068 100644
> > --- a/gcc/ccmp.cc
> > +++ b/gcc/ccmp.cc
> > @@ -247,7 +247,17 @@ expand_ccmp_expr_1 (gimple *g, rtx_insn **prep_seq,
> > rtx_insn **gen_seq)
> > cost2 = seq_cost (prep_seq_2, speed_p);
> > cost2 += seq_cost (gen_seq_2, speed_p);
> > }
> > - if (cost2 < cost1)
> > +
> > + /* For x86 target the ccmp does not support fp operands, but
> > + have fcomi insn that can produce eflags and then do int
> > + ccmp. So if one of the op is fp compare, ret1 or ret2 can
> > + fail, and the cost of the corresponding empty seq will
> > + always be smaller, then the NULL sequence will be returned.
> > + Add check for ret and ret2, returns the available one if
> > + the other is NULL. */
> > + if ((!ret && ret2)
> > + || (!(ret && !ret2)
> > + && cost2 < cost1))
> > {
> > *prep_seq = prep_seq_2;
> > *gen_seq = gen_seq_2;
> > --
> > 2.31.1
> >
