https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86685
Bug ID: 86685
Summary: [8/9 Regression] 436.cactusADM regression on aarch64
Product: gcc
Version: unknown
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: ktkachov at gcc dot gnu.org
CC: rsandifo at gcc dot gnu.org
Target Milestone: ---
For GCC 8 since r254378 we use SCHED_PRESSURE_MODEL in aarch64 during
scheduling. This gives an improvement in SPEC2017 but we have noticed it
regresses 436.cactusADM from SPEC2006 significantly. On a Cortex-A72 we see a
10% regression from that change.
The vector loop in the hot function bench_staggeredleapfrog2_ contains
significantly more stack spills. I appreciate the goal of that scheduling model
isn't necessarily to minimise stack spills, but it should do a better job at
keeping them under reasonable control
Given that SCHED_PRESSURE_MODEL works quite well for us in other cases it would
be good to fix it going haywire here to get the performance back up.
