Re: [PATCH] aarch64: add 'AARCH64_EXTRA_TUNE_FULLY_PIPELINED_FMA'

[Richard Sandiford]

Di Zhao OS <diz...@os.amperecomputing.com> writes:
> This patch adds a new tuning option 'AARCH64_EXTRA_TUNE_FULLY_PIPELINED_FMA',
> to consider fully pipelined FMAs in reassociation. Also, set this option
> by default for Ampere CPUs.
>
> Tested on aarch64-unknown-linux-gnu. Is this OK for trunk?
>
> Thanks,
> Di Zhao
>
> gcc/ChangeLog:
>
>       * config/aarch64/aarch64-tuning-flags.def (AARCH64_EXTRA_TUNING_OPTION):
>       New tuning option AARCH64_EXTRA_TUNE_FULLY_PIPELINED_FMA.
>       * config/aarch64/aarch64.cc (aarch64_override_options_internal): Set
>       param_fully_pipelined_fma according to tuning option.
>       * config/aarch64/tuning_models/ampere1.h: Add
>       AARCH64_EXTRA_TUNE_FULLY_PIPELINED_FMA to tune_flags.
>       * config/aarch64/tuning_models/ampere1a.h: Likewise.
>       * config/aarch64/tuning_models/ampere1b.h: Likewise.
>
> ---
>  gcc/config/aarch64/aarch64-tuning-flags.def | 2 ++
>  gcc/config/aarch64/aarch64.cc               | 6 ++++++
>  gcc/config/aarch64/tuning_models/ampere1.h  | 3 ++-
>  gcc/config/aarch64/tuning_models/ampere1a.h | 3 ++-
>  gcc/config/aarch64/tuning_models/ampere1b.h | 3 ++-
>  5 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/config/aarch64/aarch64-tuning-flags.def 
> b/gcc/config/aarch64/aarch64-tuning-flags.def
> index f28a73839a6..256f17bad60 100644
> --- a/gcc/config/aarch64/aarch64-tuning-flags.def
> +++ b/gcc/config/aarch64/aarch64-tuning-flags.def
> @@ -49,4 +49,6 @@ AARCH64_EXTRA_TUNING_OPTION ("matched_vector_throughput", 
> MATCHED_VECTOR_THROUGH
>  
>  AARCH64_EXTRA_TUNING_OPTION ("avoid_cross_loop_fma", AVOID_CROSS_LOOP_FMA)
>  
> +AARCH64_EXTRA_TUNING_OPTION ("fully_pipelined_FMA", FULLY_PIPELINED_FMA)

Could you change this to all-lowercase, i.e. fully_pipelined_fma,
for consistency with avoid_cross_loop_fma above?

> +
>  #undef AARCH64_EXTRA_TUNING_OPTION
> diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
> index f9850320f61..1b3b288cdf9 100644
> --- a/gcc/config/aarch64/aarch64.cc
> +++ b/gcc/config/aarch64/aarch64.cc
> @@ -18289,6 +18289,12 @@ aarch64_override_options_internal (struct 
> gcc_options *opts)
>      SET_OPTION_IF_UNSET (opts, &global_options_set, param_avoid_fma_max_bits,
>                        512);
>  
> +  /* Consider fully pipelined FMA in reassociation.  */
> +  if (aarch64_tune_params.extra_tuning_flags
> +      & AARCH64_EXTRA_TUNE_FULLY_PIPELINED_FMA)
> +    SET_OPTION_IF_UNSET (opts, &global_options_set, 
> param_fully_pipelined_fma,
> +                      1);
> +
>    aarch64_override_options_after_change_1 (opts);
>  }
>  
> diff --git a/gcc/config/aarch64/tuning_models/ampere1.h 
> b/gcc/config/aarch64/tuning_models/ampere1.h
> index a144e8f94b3..d63788528a7 100644
> --- a/gcc/config/aarch64/tuning_models/ampere1.h
> +++ b/gcc/config/aarch64/tuning_models/ampere1.h
> @@ -104,7 +104,8 @@ static const struct tune_params ampere1_tunings =
>    2, /* min_div_recip_mul_df.  */
>    0, /* max_case_values.  */
>    tune_params::AUTOPREFETCHER_WEAK,  /* autoprefetcher_model.  */
> -  (AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA), /* tune_flags.  */
> +  (AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA |
> +   AARCH64_EXTRA_TUNE_FULLY_PIPELINED_FMA),  /* tune_flags.  */

Formatting nit, but GCC style is to put the "|" at the start of the
following line:

  (AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA
   | AARCH64_EXTRA_TUNE_FULLY_PIPELINED_FMA),   /* tune_flags.  */

Same for the others.

OK with those changes, thanks.

Richard

>    &ampere1_prefetch_tune,
>    AARCH64_LDP_STP_POLICY_ALIGNED,   /* ldp_policy_model.  */
>    AARCH64_LDP_STP_POLICY_ALIGNED    /* stp_policy_model.  */
> diff --git a/gcc/config/aarch64/tuning_models/ampere1a.h 
> b/gcc/config/aarch64/tuning_models/ampere1a.h
> index f688ed08a79..63506e1d1c6 100644
> --- a/gcc/config/aarch64/tuning_models/ampere1a.h
> +++ b/gcc/config/aarch64/tuning_models/ampere1a.h
> @@ -56,7 +56,8 @@ static const struct tune_params ampere1a_tunings =
>    2, /* min_div_recip_mul_df.  */
>    0, /* max_case_values.  */
>    tune_params::AUTOPREFETCHER_WEAK,  /* autoprefetcher_model.  */
> -  (AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA), /* tune_flags.  */
> +  (AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA |
> +   AARCH64_EXTRA_TUNE_FULLY_PIPELINED_FMA),  /* tune_flags.  */
>    &ampere1_prefetch_tune,
>    AARCH64_LDP_STP_POLICY_ALIGNED,   /* ldp_policy_model.  */
>    AARCH64_LDP_STP_POLICY_ALIGNED    /* stp_policy_model.  */
> diff --git a/gcc/config/aarch64/tuning_models/ampere1b.h 
> b/gcc/config/aarch64/tuning_models/ampere1b.h
> index a98b6a980f7..7894e730174 100644
> --- a/gcc/config/aarch64/tuning_models/ampere1b.h
> +++ b/gcc/config/aarch64/tuning_models/ampere1b.h
> @@ -106,7 +106,8 @@ static const struct tune_params ampere1b_tunings =
>    0, /* max_case_values.  */
>    tune_params::AUTOPREFETCHER_STRONG,        /* autoprefetcher_model.  */
>    (AARCH64_EXTRA_TUNE_CHEAP_SHIFT_EXTEND |
> -   AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA), /* tune_flags.  */
> +   AARCH64_EXTRA_TUNE_AVOID_CROSS_LOOP_FMA |
> +   AARCH64_EXTRA_TUNE_FULLY_PIPELINED_FMA),  /* tune_flags.  */
>    &ampere1b_prefetch_tune,
>    AARCH64_LDP_STP_POLICY_ALIGNED,   /* ldp_policy_model.  */
>    AARCH64_LDP_STP_POLICY_ALIGNED    /* stp_policy_model.  */