On Wed, Aug 28, 2024 at 6:34 AM Andrew Pinski <quic_apin...@quicinc.com> wrote:
>
> While working on PR 114224, I found it would be useful to dump the
> different costs of the expansion to make easier to understand why one
> was chosen over the other.
>
> Bootstrapped and tested on x86_64-linux-gnu.
> Build and tested for aarch64-linux-gnu.
>
> gcc/ChangeLog:
>
> * internal-fn.cc (expand_POPCOUNT): Dump the costs for
> the two choices.
> ---
> gcc/internal-fn.cc | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/gcc/internal-fn.cc b/gcc/internal-fn.cc
> index 89da13b38ce..91210976a0a 100644
> --- a/gcc/internal-fn.cc
> +++ b/gcc/internal-fn.cc
> @@ -5351,6 +5351,14 @@ expand_POPCOUNT (internal_fn fn, gcall *stmt)
> unsigned popcount_cost = (seq_cost (popcount_insns, speed_p)
> + seq_cost (popcount_cmp_insns, speed_p));
> unsigned cmp_cost = seq_cost (cmp_insns, speed_p);
> +
> + if (dump_file && (dump_flags & TDF_DETAILS))
> + {
> + fprintf(dump_file, "popcount == 1, cost\n");
> + fprintf(dump_file, "popcount: %u\n", popcount_cost);
> + fprintf(dump_file, "cmp: %u\n\n", cmp_cost);
Can you make this more brief in a single line, like
choice for popcount == 1: popcount cost: %u; cmp cost: %u\n
?
OK with that change.
> + }
> +
> if (popcount_cost <= cmp_cost)
> emit_insn (popcount_insns);
> else
> --
> 2.43.0
>
