Re: [PATCH] target/108738 - optimize bit operations in STV

[Uros Bizjak <ubizjak@gmail.com>]

On Thu, Feb 9, 2023 at 3:25 PM Richard Biener via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> The following does low-hanging optimizations, combining bitmap
> test and set and removing redundant operations.
>
> This shaves off half of the testcase compile time.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, OK?
>
> Thanks,
> Richard.
>
>         PR target/108738
>         * config/i386/i386-features.cc (scalar_chain::add_to_queue):
>         Combine bitmap test and set.
>         (scalar_chain::add_insn): Likewise.
>         (scalar_chain::analyze_register_chain): Remove redundant
>         attempt to add to queue and instead strengthen assert.
>         Sink common attempts to mark the def dual-mode.
>         (scalar_chain::add_to_queue): Remove redundant insn bitmap
>         check.

LGTM.

Thanks,
Uros.

> ---
>  gcc/config/i386/i386-features.cc | 18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc
> index 9bd6d8677bb..eff91301009 100644
> --- a/gcc/config/i386/i386-features.cc
> +++ b/gcc/config/i386/i386-features.cc
> @@ -314,14 +314,12 @@ scalar_chain::~scalar_chain ()
>  void
>  scalar_chain::add_to_queue (unsigned insn_uid)
>  {
> -  if (bitmap_bit_p (insns, insn_uid)
> -      || bitmap_bit_p (queue, insn_uid))
> +  if (!bitmap_set_bit (queue, insn_uid))
>      return;
>
>    if (dump_file)
>      fprintf (dump_file, "  Adding insn %d into chain's #%d queue\n",
>              insn_uid, chain_id);
> -  bitmap_set_bit (queue, insn_uid);
>  }
>
>  /* For DImode conversion, mark register defined by DEF as requiring
> @@ -362,10 +360,9 @@ void
>  scalar_chain::analyze_register_chain (bitmap candidates, df_ref ref)
>  {
>    df_link *chain;
> +  bool mark_def = false;
>
> -  gcc_assert (bitmap_bit_p (insns, DF_REF_INSN_UID (ref))
> -             || bitmap_bit_p (candidates, DF_REF_INSN_UID (ref)));
> -  add_to_queue (DF_REF_INSN_UID (ref));
> +  gcc_checking_assert (bitmap_bit_p (insns, DF_REF_INSN_UID (ref)));
>
>    for (chain = DF_REF_CHAIN (ref); chain; chain = chain->next)
>      {
> @@ -398,9 +395,12 @@ scalar_chain::analyze_register_chain (bitmap candidates, df_ref ref)
>           if (dump_file)
>             fprintf (dump_file, "  r%d use in insn %d isn't convertible\n",
>                      DF_REF_REGNO (chain->ref), uid);
> -         mark_dual_mode_def (ref);
> +         mark_def = true;
>         }
>      }
> +
> +  if (mark_def)
> +    mark_dual_mode_def (ref);
>  }
>
>  /* Add instruction into a chain.  */
> @@ -408,14 +408,12 @@ scalar_chain::analyze_register_chain (bitmap candidates, df_ref ref)
>  void
>  scalar_chain::add_insn (bitmap candidates, unsigned int insn_uid)
>  {
> -  if (bitmap_bit_p (insns, insn_uid))
> +  if (!bitmap_set_bit (insns, insn_uid))
>      return;
>
>    if (dump_file)
>      fprintf (dump_file, "  Adding insn %d to chain #%d\n", insn_uid, chain_id);
>
> -  bitmap_set_bit (insns, insn_uid);
> -
>    rtx_insn *insn = DF_INSN_UID_GET (insn_uid)->insn;
>    rtx def_set = single_set (insn);
>    if (def_set && REG_P (SET_DEST (def_set))
> --
> 2.35.3