https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104762
Bug ID: 104762
Summary: x86_64 538.imagick_r 8%-28% regressions after
r12-7319-g90d693bdc9d718
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: jamborm at gcc dot gnu.org
CC: rguenth at gcc dot gnu.org
Blocks: 26163
Target Milestone: ---
Host: x86_64-linux
Target: x86_64-linux
Around 22nd of February 2022, SPEC 2017 538.imagick_r regressed on all
x86_64 systems used by our periodic benchmarker. I have bisected the
zen3 -Ofast -march=native -flto case to revision
r12-7319-g90d693bdc9d718 but I think most if not all of the
regressions are caused by this:
commit 90d693bdc9d71841f51d68826ffa5bd685d7f0bc
Author: Richard Biener <rguent...@suse.de>
Date: Fri Feb 18 14:32:14 2022 +0100
target/99881 - x86 vector cost of CTOR from integer regs
This uses the now passed SLP node to the vectorizer costing hook
to adjust vector construction costs for the cost of moving an
integer component from a GPR to a vector register when that's
required for building a vector from components. A cruical difference
here is whether the component is loaded from memory or extracted
from a vector register as in those cases no intermediate GPR is involved.
The pr99881.c testcase can be Un-XFAILed with this patch, the
pr91446.c testcase now produces scalar code which looks superior
to me so I've adjusted it as well.
List of (selected) regressions with links to LNT graphs:
zen2 -O2 regressed by 26%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=297.507.0
zen2 -O2 -flto regressed by 26% too:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=296.507.0
zen2 -Ofast -march=native by 28%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=295.507.0
zen2 -Ofast -march=native -flto by 23:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=287.507.0
zen3 -O2 by 8%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=470.507.0
zen3 -O2 -march=native by 18%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=472.507.0
zen3 -Ofast -march=native by 17%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=471.507.0
zen3 -Ofast -march=native -flto by 10%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=475.507.0
kabylake -O2 by 9%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=226.507.0
(though this one looks suspiciously noisy)
kabylake -O2 -march=native by 16%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=28.507.0
kabylake -Ofast -march=native by 22%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=32.507.0
kabylake -Ofast -march=native -flto by 15%:
https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=11.507.0
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=26163
[Bug 26163] [meta-bug] missed optimization in SPEC (2k17, 2k and 2k6 and 95)
