https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100393
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Samples: 847K of event 'cycles:u', Event count (approx.): 839745061761
Overhead Samples Command Shared Object Symbol
95.05% 804298 cc1 cc1 [.]
tree_switch_conversion::jump_table_cluster::can_be_handled
1.69% 14493 cc1 cc1 [.]
tree_switch_conversion::cluster::get_range
0.86% 7291 cc1 cc1 [.]
optimize_function_for_size_p
looks like there's obvious quadraticness here when doing the summing:
bool
jump_table_cluster::can_be_handled (const vec<cluster *> &clusters,
unsigned start, unsigned end)
{
..
for (unsigned i = start; i <= end; i++)
{
simple_cluster *sc = static_cast<simple_cluster *> (clusters[i]);
comparison_count += sc->m_range_p ? 2 : 1;
}
and we're almost trying all possible clusters in
jump_table_cluster::find_jump_tables
Now, there's the possibility of doing a quick guess before doing this
loop, once via using (end - start) and once via using 2 * (end - start).
Only if the first can be handled and the second not we have to compute.
Martin?
