On Tue, Jan 18, 2022 at 11:13 PM HAO CHEN GUI via Gcc-patches
<gcc-patches@gcc.gnu.org> 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 <guih...@linux.ibm.com>
>
> 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
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);
> +}
