On Wed, Jan 19, 2022 at 6:12 PM HAO CHEN GUI <[email protected]> wrote:
>
>
>
> On 19/1/2022 下午 3:52, Andrew Pinski wrote:
> > On Tue, Jan 18, 2022 at 11:13 PM HAO CHEN GUI via Gcc-patches
> > <[email protected]> wrote:
> >>
> >> Hi,
> >> This patch adds a combine pattern for "CA minus one". As CA only has two
> >> values (0 or 1), we could convert following pattern
> >> (sign_extend:DI (plus:SI (reg:SI 98 ca)
> >> (const_int -1 [0xffffffffffffffff]))))
> >> to
> >> (plus:DI (reg:DI 98 ca)
> >> (const_int -1 [0xffffffffffffffff])))
> >> With this patch, it eliminates one unnecessary sign extend. Also in
> >> rs6000,
> >> regclass of CA register is set to NO_REGS. So CA is not in hard register
> >> set
> >> and it can't match register_operand. The patch changes it to any_operand.
> >>
> >> Bootstrapped and tested on powerpc64-linux BE and LE with no
> >> regressions.
> >> Is this okay for trunk? Any recommendations? Thanks a lot.
> >>
> >> ChangeLog
> >> 2022-01-19 Haochen Gui <[email protected]>
> >>
> >> gcc/
> >> * config/rs6000/predicates.md (ca_operand): Match any_operand as CA
> >> register is not in hard register set.
> >> * config/rs6000/rs6000.md (extenddi_ca_minus_one): Define.
> >>
> >> gcc/testsuite/
> >> * gcc.target/powerpc/pr95737.c: New.
> >>
> >>
> >> patch.diff
> >> diff --git a/gcc/config/rs6000/predicates.md
> >> b/gcc/config/rs6000/predicates.md
> >> index c65dfb91f3d..cd2ae1dc8e0 100644
> >> --- a/gcc/config/rs6000/predicates.md
> >> +++ b/gcc/config/rs6000/predicates.md
> >> @@ -188,7 +188,7 @@ (define_predicate "vlogical_operand"
> >>
> >> ;; Return 1 if op is the carry register.
> >> (define_predicate "ca_operand"
> >> - (match_operand 0 "register_operand")
> >> + (match_operand 0 "any_operand")
> >> {
> >> if (SUBREG_P (op))
> >> op = SUBREG_REG (op);
> >> diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
> >> index 6ecb0bd6142..f1b09aad3b5 100644
> >> --- a/gcc/config/rs6000/rs6000.md
> >> +++ b/gcc/config/rs6000/rs6000.md
> >> @@ -2358,6 +2358,21 @@ (define_insn "subf<mode>3_carry_in_xx"
> >> "subfe %0,%0,%0"
> >> [(set_attr "type" "add")])
> >>
> >> +(define_insn_and_split "*extenddi_ca_minus_one"
> >> + [(set (match_operand:DI 0 "gpc_reg_operand")
> >> + (sign_extend:DI (plus:SI (match_operand:SI 1 "ca_operand")
> >> + (const_int -1))))]
> >> + ""
> >> + "#"
> >> + ""
> >> + [(parallel [(set (match_dup 0)
> >> + (plus:DI (match_dup 2)
> >> + (const_int -1)))
> >> + (clobber (match_dup 2))])]
> >> +{
> >> + operands[2] = copy_rtx (operands[1]);
> >> + PUT_MODE (operands[2], DImode);
> >> +})
> >
> > There are a few things missing I think for this to be correct.
> > I think it should be:
> > (define_insn_and_split "*extenddi_ca_minus_one"
> > [(set (match_operand:DI 0 "gpc_reg_operand" "=r")
> > (sign_extend:DI (plus:SI (reg:SI CA_REGNO)
> > (const_int -1))))]
> > ""
> > "#"
> > "&& reload_completed"
> > [(parallel [(set (match_dup 0)
> > (plus:DI (reg:DI CA_REGNO)
> > (const_int -1)))
> > (clobber (reg:DI CA_REGNO))])]
> > {})
> >
> > There is no reason to change ca_operand either since
> > subf<mode>3_carry_in_xx already hard codes the CA_REGNO too; you can
> Yes, we can directly use CA_REGNO. It makes the pattern compact.
> But why it needs reload_completed? Could you explain it?
Actually you are right, there is no reason for the reload_completed any more.
It was definitely needed before when you were doing PUT_MODE as I
didn't trust how ca_operand would have caught only the CA_REGNO
register.
Thanks,
Andrew
>
> Thanks.
> Gui Haochen
>
> > just use it directly like above.
> >
> > Sorry for the incorrect whitespace formatting though.
> >
> > Thanks,
> > Andrew Pinski
> >
> >>
> >> (define_insn "@neg<mode>2"
> >> [(set (match_operand:GPR 0 "gpc_reg_operand" "=r")
> >> diff --git a/gcc/testsuite/gcc.target/powerpc/pr95737.c
> >> b/gcc/testsuite/gcc.target/powerpc/pr95737.c
> >> new file mode 100644
> >> index 00000000000..94320f23423
> >> --- /dev/null
> >> +++ b/gcc/testsuite/gcc.target/powerpc/pr95737.c
> >> @@ -0,0 +1,10 @@
> >> +/* PR target/95737 */
> >> +/* { dg-do compile { target lp64 } } */
> >> +/* { dg-options "-O2 -mdejagnu-cpu=power8" } */
> >> +/* { dg-final { scan-assembler-not {\mextsw\M} } } */
> >> +
> >> +
> >> +unsigned long long negativeLessThan (unsigned long long a, unsigned long
> >> long b)
> >> +{
> >> + return -(a < b);
> >> +}
