https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69274
--- Comment #12 from Richard Biener <rguenth at gcc dot gnu.org> ---
Key assembly difference seems to be extra reg-reg copies around a loop. But
maybe
perf lies to me (the description cites fsettle as the real offender but perf
points me to inl1130). As I can reproduce the isssue even w/o
-fschedule-insns2
I doubted the issue was scheduling related (but I didn't try if
-fschedule-insns fixed things).
Both loops are rather large though (and vectorized).
perf for me shows (reproducible)
Samples: 2M of event 'cycles', Event count (approx.): 2251122016217
31.85% gromacs_base.am gromacs_base.amd64-m64-gcc42-nn [.] inl1130_
24.64% gromacs_peak.am gromacs_peak.amd64-m64-gcc42-nn [.] inl1130_
6.46% gromacs_base.am gromacs_base.amd64-m64-gcc42-nn [.]
search_neighbour
6.39% gromacs_peak.am gromacs_peak.amd64-m64-gcc42-nn [.]
search_neighbour
1.70% gromacs_base.am gromacs_base.amd64-m64-gcc42-nn [.] inl1100_
1.69% gromacs_peak.am gromacs_peak.amd64-m64-gcc42-nn [.] inl1100_
0.96% gromacs_base.am gromacs_base.amd64-m64-gcc42-nn [.] inl1000_
0.96% gromacs_peak.am gromacs_peak.amd64-m64-gcc42-nn [.] inl1000_
0.86% gromacs_base.am gromacs_base.amd64-m64-gcc42-nn [.] inl0100_
0.85% gromacs_peak.am gromacs_peak.amd64-m64-gcc42-nn [.] inl0100_
0.75% gromacs_base.am gromacs_base.amd64-m64-gcc42-nn [.] inl1120_
0.70% gromacs_peak.am gromacs_peak.amd64-m64-gcc42-nn [.] fsettle_
0.68% gromacs_base.am gromacs_base.amd64-m64-gcc42-nn [.] fsettle_
0.65% gromacs_peak.am gromacs_peak.amd64-m64-gcc42-nn [.] inl1120_
0.61% gromacs_base.am gromacs_base.amd64-m64-gcc42-nn [.] update
0.61% gromacs_peak.am gromacs_peak.amd64-m64-gcc42-nn [.] update
thus not fsettle but the attached.
BASE separated:
Samples: 1M of event 'cycles', Event count (approx.): 1045723281935,
DSO: gromac
68.56% gromacs_base.am [.] inl1130_
13.92% gromacs_base.am [.] search_neighbours
3.65% gromacs_base.am [.] inl1100_
2.07% gromacs_base.am [.] inl1000_
1.84% gromacs_base.am [.] inl0100_
1.61% gromacs_base.am [.] inl1120_
1.47% gromacs_base.am [.] fsettle_
PEAK separated:
Samples: 1M of event 'cycles', Event count (approx.): 879799417599, DSO:
gromacs
63.05% gromacs_peak.am [.] inl1130_
16.35% gromacs_peak.am [.] search_neighbours
4.33% gromacs_peak.am [.] inl1100_
2.45% gromacs_peak.am [.] inl1000_
2.18% gromacs_peak.am [.] inl0100_
1.79% gromacs_peak.am [.] fsettle_
1.66% gromacs_peak.am [.] inl1120_
1.56% gromacs_peak.am [.] update
1.56% gromacs_peak.am [.] put_in_list.constprop.14
