https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87528
Bug ID: 87528
Summary: Popcount changes caused 531.deepsjeng_r run-time
regression on Skylake
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: jamborm at gcc dot gnu.org
Target Milestone: ---
According to my repeated measurements, r262486 and r262864 caused ~14%
regression (roughly 7% and 7% each) in run-time of SPEC 2017
531.deepsjeng_r, with generic tuning (only), both at -O2 and -Ofast,
on an Intel Skylake machine (Intel Xeon Platinum 8164 CPU).
Martin Liška could not reproduce this on his Kabylake machine, so I'd
be very grateful if someone else could attempt to reproduce this.
Having said that, I really can reproduce the regression very reliably.
