https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82220
Bug ID: 82220
Summary: [8 Regression] SPEC CPU2006 482.sphinx3 ~10%
performance regression with trunk@250416
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: alexander.nesterovskiy at intel dot com
Target Milestone: ---
Calculation of a min_profitable_iters threshold was changed in r250416
In 482.sphinx3 a wrong path is chosen in a hottest loop which leads to ~45%
performance drop for a particular loop and ~10% performance drop for a whole
test.
According to perf report:
---
Overhead Samples Symbol
trunk@250416 (and up-to-date trunk@252756)
36.91% --> 527019 vector_gautbl_eval_logs3
28.03% 400316 mgau_eval
8.90% 127071 subvq_mgau_shortlist
trunk@250415
31.72% 402114 mgau_eval
29.36% --> 372126 vector_gautbl_eval_logs3
9.85% 124815 subvq_mgau_shortlist
---
Compiled with: "-Ofast -funroll-loops -march=core-avx2 -mfpmath=sse"
