Re: [PATCH 1/8] [APX NF]: Support APX NF add

[Uros Bizjak <ubizjak@gmail.com>]

On Wed, May 15, 2024 at 9:43 AM Kong, Lingling <lingling.kong@intel.com> wrote:
>
> From: Hongyu Wang <hongyu.wang@intel.com>
>
> APX NF(no flags) feature implements suppresses the update of status flags for arithmetic operations.
>
> For NF add, it is not clear whether NF add can be faster than lea. If so, the pattern needs to be adjusted to prefer LEA generation.
>
> gcc/ChangeLog:
>
>         * config/i386/i386-opts.h (enum apx_features): Add nf
>         enumeration.
>         * config/i386/i386.h (TARGET_APX_NF): New.
>         * config/i386/i386.md (*add<mode>_1_nf): New define_insn.
>         * config/i386/i386.opt: Add apx_nf enumeration.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/i386/apx-ndd.c: Fixed test.
>         * gcc.target/i386/apx-nf.c: New test.
>
> Co-authored-by: Lingling Kong <lingling.kong@intel.com>
>
> Bootstrapped and regtested on x86_64-linux-gnu. And Supported SPEC 2017 run normally on Intel software development emulator.
> Ok for trunk?
>
> ---
>  gcc/config/i386/i386-opts.h             |  3 +-
>  gcc/config/i386/i386.h                  |  1 +
>  gcc/config/i386/i386.md                 | 42 +++++++++++++++++++++++++
>  gcc/config/i386/i386.opt                |  3 ++
>  gcc/testsuite/gcc.target/i386/apx-ndd.c |  2 +-
>  gcc/testsuite/gcc.target/i386/apx-nf.c  |  6 ++++
>  6 files changed, 55 insertions(+), 2 deletions(-)  create mode 100644 gcc/testsuite/gcc.target/i386/apx-nf.c
>
> diff --git a/gcc/config/i386/i386-opts.h b/gcc/config/i386/i386-opts.h index ef2825803b3..60176ce609f 100644
> --- a/gcc/config/i386/i386-opts.h
> +++ b/gcc/config/i386/i386-opts.h
> @@ -140,7 +140,8 @@ enum apx_features {
>    apx_push2pop2 = 1 << 1,
>    apx_ndd = 1 << 2,
>    apx_ppx = 1 << 3,
> -  apx_all = apx_egpr | apx_push2pop2 | apx_ndd | apx_ppx,
> +  apx_nf = 1<< 4,
> +  apx_all = apx_egpr | apx_push2pop2 | apx_ndd | apx_ppx | apx_nf,
>  };
>
>  #endif
> diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h index 529edff93a4..f20ae4726da 100644
> --- a/gcc/config/i386/i386.h
> +++ b/gcc/config/i386/i386.h
> @@ -55,6 +55,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see  #define TARGET_APX_PUSH2POP2 (ix86_apx_features & apx_push2pop2)  #define TARGET_APX_NDD (ix86_apx_features & apx_ndd)  #define TARGET_APX_PPX (ix86_apx_features & apx_ppx)
> +#define TARGET_APX_NF (ix86_apx_features & apx_nf)
>
>  #include "config/vxworks-dummy.h"
>
> diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md index 764bfe20ff2..4a9e35c4990 100644
> --- a/gcc/config/i386/i386.md
> +++ b/gcc/config/i386/i386.md
> @@ -6233,6 +6233,48 @@
>      }
>  })
>
>
> +;; NF instructions.
> +
> +(define_insn "*add<mode>_1_nf"
> +  [(set (match_operand:SWI 0 "nonimmediate_operand" "=rm,rje,r,r,r,r,r,r")
> +       (plus:SWI
> +         (match_operand:SWI 1 "nonimmediate_operand" "%0,0,0,r,r,rje,jM,r")
> +         (match_operand:SWI 2 "x86_64_general_operand"
> +"r,e,BM,0,le,r,e,BM")))]
> +  "TARGET_APX_NF &&
> +   ix86_binary_operator_ok (PLUS, <MODE>mode, operands,
> +                           TARGET_APX_NDD)"

I wonder if we can use "define_subst" to conditionally add flags
clobber for !TARGET_APX_NF targets. Even the example for "Define
Subst" uses the insn w/ and w/o the clobber, so I think it is worth
considering this approach.

Uros.