On Thu, 10 Sep 2026, Aldy Hernandez wrote:
> There are two insn counts now. Rename this one to say what it is, the
> path's insns less the branch we get to remove. This keeps it distinct
> from path_stats::n_insns, the running total.
But why does m_net_insns have to be a class member rather than
a local variable in
back_threader_profitability::possibly_profitable_path_p?
It gets overridden each time it is called?
> gcc/ChangeLog:
>
> * tree-ssa-threadbackward.cc (back_threader_profitability):
> Rename m_n_insns to m_net_insns.
> (back_threader_profitability::possibly_profitable_path_p):
> Adjust.
> (back_threader_profitability::profitable_path_p): Adjust.
> ---
> gcc/tree-ssa-threadbackward.cc | 24 ++++++++++++------------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/gcc/tree-ssa-threadbackward.cc b/gcc/tree-ssa-threadbackward.cc
> index 03a7e1db50c..dd53c99db96 100644
> --- a/gcc/tree-ssa-threadbackward.cc
> +++ b/gcc/tree-ssa-threadbackward.cc
> @@ -86,7 +86,7 @@ private:
> };
> path_stats m_stats;
> // Number of insns on the path, less the branch we get to remove.
> - int m_n_insns;
> + int m_net_insns;
> // One entry per push. These are the stats as they stood before that push,
> // and the insns of the block. Basically the entry pushed for m_path[i]
> // accounts m_path[i - 1].
> @@ -762,12 +762,12 @@ back_threader_profitability::possibly_profitable_path_p
> /* We are going to remove the control statement at the end of the
> last block in the threading path. So don't count it against our
> statement count. */
> - m_n_insns = m_stats.n_insns - m_exit_jump_benefit;
> + m_net_insns = m_stats.n_insns - m_exit_jump_benefit;
>
> if (dump_file && (dump_flags & TDF_DETAILS))
> fprintf (dump_file, "\n Control statement insns: %i\n"
> " Overall: %i insns\n",
> - m_exit_jump_benefit, m_n_insns);
> + m_exit_jump_benefit, m_net_insns);
>
> /* Threading is profitable if the path duplicated is hot but also
> in a case we separate cold path from hot path and permit optimization
> @@ -775,7 +775,7 @@ back_threader_profitability::possibly_profitable_path_p
> as in PR 78407 this leads to noticeable improvements. */
> if (m_speed_p)
> {
> - if (m_n_insns >= param_max_fsm_thread_path_insns)
> + if (m_net_insns >= param_max_fsm_thread_path_insns)
> {
> if (dump_file && (dump_flags & TDF_DETAILS))
> fprintf (dump_file, " FAIL: Jump-thread path not considered: "
> @@ -793,12 +793,12 @@ back_threader_profitability::possibly_profitable_path_p
> return false;
> }
> }
> - else if (m_n_insns > 1)
> + else if (m_net_insns > 1)
> {
> if (dump_file && (dump_flags & TDF_DETAILS))
> fprintf (dump_file, " FAIL: Jump-thread path not considered: "
> "duplication of %i insns is needed and optimizing for size.\n",
> - m_n_insns);
> + m_net_insns);
> return false;
> }
>
> @@ -811,7 +811,7 @@ back_threader_profitability::possibly_profitable_path_p
> if ((!m_threaded_multiway_branch
> || !loop->latch
> || loop->latch->index == EXIT_BLOCK)
> - && (m_n_insns * param_fsm_scale_path_stmts
> + && (m_net_insns * param_fsm_scale_path_stmts
> >= param_max_jump_thread_duplication_stmts))
> {
> if (dump_file && (dump_flags & TDF_DETAILS))
> @@ -822,7 +822,7 @@ back_threader_profitability::possibly_profitable_path_p
> }
> *large_non_fsm = (!(m_stats.threaded_through_latch
> && m_threaded_multiway_branch)
> - && (m_n_insns * param_fsm_scale_path_stmts
> + && (m_net_insns * param_fsm_scale_path_stmts
> >= param_max_jump_thread_duplication_stmts));
>
> if (dump_file && (dump_flags & TDF_DETAILS))
> @@ -878,12 +878,12 @@ back_threader_profitability::profitable_path_p (const
> vec<basic_block> &m_path,
> return false;
> }
> }
> - else if (m_n_insns > 1)
> + else if (m_net_insns > 1)
> {
> if (dump_file && (dump_flags & TDF_DETAILS))
> fprintf (dump_file, " FAIL: Jump-thread path not considered: "
> "duplication of %i insns is needed and optimizing for size.\n",
> - m_n_insns);
> + m_net_insns);
> return false;
> }
>
> @@ -896,7 +896,7 @@ back_threader_profitability::profitable_path_p (const
> vec<basic_block> &m_path,
> if (!m_threaded_multiway_branch
> && *creates_irreducible_loop
> && (!(cfun->curr_properties & PROP_loop_opts_done)
> - || (m_n_insns * param_fsm_scale_path_stmts
> + || (m_net_insns * param_fsm_scale_path_stmts
> >= param_max_jump_thread_duplication_stmts)))
> {
> if (dump_file && (dump_flags & TDF_DETAILS))
> @@ -912,7 +912,7 @@ back_threader_profitability::profitable_path_p (const
> vec<basic_block> &m_path,
> case, drastically reduce the number of statements we are allowed
> to copy. */
> if (!(m_stats.threaded_through_latch && m_threaded_multiway_branch)
> - && (m_n_insns * param_fsm_scale_path_stmts
> + && (m_net_insns * param_fsm_scale_path_stmts
> >= param_max_jump_thread_duplication_stmts))
> {
> if (dump_file && (dump_flags & TDF_DETAILS))
>
--
Richard Biener <[email protected]>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Jochen Jaser, Andrew McDonald, Abhinav Puri; (HRB 36809, AG Nuernberg)
