Re: [PATCH] genopinit: Split init_all_optabs [PR113575]

[Richard Biener <richard.guenther@gmail.com>]

On Fri, Jan 26, 2024 at 9:17 AM Robin Dapp <rdapp.gcc@gmail.com> wrote:
>
> Hi,
>
> init_all_optabs initializes > 10000 patterns for riscv targets.  This
> leads to pathological situations in dataflow analysis (which can occur
> with many adjacent stores).
> To alleviate this this patch makes genopinit split the init_all_optabs
> function into several init_optabs_xx functions that each initialize 1000
> patterns.
>
> With this change insn-opinit.cc's compilation time is reduced from 4+
> minutes to 1:30 and memory consumption decreases from 1.2G to 630M.
>
> Bootstrapped and regtested on x86 and aarch64 (where we do split) and
> on power10 (where we don't).  Regtested on riscv.

OK.

Thanks,
Richard.

> Regards
>  Robin
>
> gcc/ChangeLog:
>
>         PR other/113575
>
>         * genopinit.cc (main): Split init_all_optabs into functions
>         of 1000 patterns each.
> ---
>  gcc/genopinit.cc | 43 ++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 38 insertions(+), 5 deletions(-)
>
> diff --git a/gcc/genopinit.cc b/gcc/genopinit.cc
> index 88ccafa5b2c..d8682b2a9ad 100644
> --- a/gcc/genopinit.cc
> +++ b/gcc/genopinit.cc
> @@ -367,11 +367,44 @@ main (int argc, const char **argv)
>      fprintf (s_file, "  { %#08x, CODE_FOR_%s },\n", p->sort_num, p->name);
>    fprintf (s_file, "};\n\n");
>
> -  fprintf (s_file, "void\ninit_all_optabs (struct target_optabs *optabs)\n{\n");
> -  fprintf (s_file, "  bool *ena = optabs->pat_enable;\n");
> -  for (i = 0; patterns.iterate (i, &p); ++i)
> -    fprintf (s_file, "  ena[%u] = HAVE_%s;\n", i, p->name);
> -  fprintf (s_file, "}\n\n");
> +  /* Some targets like riscv have a large number of patterns.  In order to
> +     prevent pathological situations in dataflow analysis split the init
> +     function into separate ones that initialize 1000 patterns each.  */
> +
> +  const int patterns_per_function = 1000;
> +
> +  if (patterns.length () > patterns_per_function)
> +    {
> +      unsigned num_init_functions
> +       = patterns.length () / patterns_per_function + 1;
> +      for (i = 0; i < num_init_functions; i++)
> +       {
> +         fprintf (s_file, "static void\ninit_optabs_%02d "
> +                  "(struct target_optabs *optabs)\n{\n", i);
> +         fprintf (s_file, "  bool *ena = optabs->pat_enable;\n");
> +         unsigned start = i * patterns_per_function;
> +         unsigned end = MIN (patterns.length (),
> +                             (i + 1) * patterns_per_function);
> +         for (j = start; j < end; ++j)
> +           fprintf (s_file, "  ena[%u] = HAVE_%s;\n", j, patterns[j].name);
> +         fprintf (s_file, "}\n\n");
> +       }
> +
> +      fprintf (s_file, "void\ninit_all_optabs "
> +              "(struct target_optabs *optabs)\n{\n");
> +      for (i = 0; i < num_init_functions; ++i)
> +       fprintf (s_file, "  init_optabs_%02d (optabs);\n", i);
> +      fprintf (s_file, "}\n\n");
> +    }
> +  else
> +    {
> +      fprintf (s_file, "void\ninit_all_optabs "
> +              "(struct target_optabs *optabs)\n{\n");
> +      fprintf (s_file, "  bool *ena = optabs->pat_enable;\n");
> +      for (i = 0; patterns.iterate (i, &p); ++i)
> +       fprintf (s_file, "  ena[%u] = HAVE_%s;\n", i, p->name);
> +      fprintf (s_file, "}\n\n");
> +    }
>
>    fprintf (s_file,
>            "/* Returns TRUE if the target supports any of the partial vector\n"
> --
> 2.43.0