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[Bug ipa/84149] New: [8 Regression] SPEC CPU2017 505.mcf/605.mcf ~10% performance regression with r256888
- From: "alexander.nesterovskiy at intel dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 31 Jan 2018 13:55:47 +0000
- Subject: [Bug ipa/84149] New: [8 Regression] SPEC CPU2017 505.mcf/605.mcf ~10% performance regression with r256888
- Auto-submitted: auto-generated
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84149
Bug ID: 84149
Summary: [8 Regression] SPEC CPU2017 505.mcf/605.mcf ~10%
performance regression with r256888
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: alexander.nesterovskiy at intel dot com
CC: marxin at gcc dot gnu.org
Target Milestone: ---
Minimal options to reproduce regression (x86, 64-bit):
-O3 -flto
The reason behind the regression is that since r256888 a cost_compare function
is not inlined into spec_qsort.
These two functions are in different source files.
I've managed to force cost_compare to be inlined by creating in the same source
file a copy of spec_qsort function with explicit calls of cost_compare.
This reverted performance to r256887 level.