From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 6141D3858292; Fri, 4 Nov 2022 17:26:27 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6141D3858292 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1667582787; bh=iHG02W+oAWxnT3xN5nMORmPqZK1xHk6EMrEoPp7FQZM=; h=From:To:Subject:Date:In-Reply-To:References:From; b=B1kaI9R1wLarMPPj1jAi2RWNj+waYBESJwqTMIStoqWF0piiAISrhw2ref6llJiLV TL0yJC5Rp6F4cEPznXK2vFvq4c16QvZl7i+5z+AVNQ34pqd9kMZuyP+X3dONeGwai8 w1rnqjyc6GU6k+HuTvjYKkhNYz7ypUu7yR6lo93c= From: "wilco at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/107413] Perf loss ~14% on 519.lbm_r SPEC cpu2017 benchmark with r8-7132-gb5b33e113434be Date: Fri, 04 Nov 2022 17:26:26 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 13.0 X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: wilco at gcc dot gnu.org X-Bugzilla-Status: ASSIGNED X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: wilco at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: everconfirmed cf_reconfirmed_on bug_status assigned_to Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 List-Id: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107413 Wilco changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Last reconfirmed| |2022-11-04 Status|UNCONFIRMED |ASSIGNED Assignee|unassigned at gcc dot gnu.org |wilco at gcc dot gn= u.org --- Comment #10 from Wilco --- (In reply to Rama Malladi from comment #9) > (In reply to Rama Malladi from comment #8) > > (In reply to Wilco from comment #7) > > > The revert results in about 0.5% loss on Neoverse N1, so it looks lik= e the > > > reassociation pass is still splitting FMAs into separate MUL and ADD = (which > > > is bad for narrow cores). > >=20 > > Thank you for checking on N1. Did you happen to check on V1 too to repr= oduce > > the perf results I had? Any other experiments/ tests I can do to help on > > this filing? Thanks again for the debug/ fix. >=20 > I ran SPEC cpu2017 fprate 1-copy benchmark built with the patch reverted = and > using option 'neoverse-n1' on the Graviton 3 processor (which has support > for SVE). The performance was up by 0.4%, primary contributor being > 519.lbm_r which was up 13%. I'm seeing about 1.5% gain on Neoverse V1 and 0.5% loss on Neoverse N1. I'll post a patch that allows per-CPU settings for FMA reassociation, so you'll = get good performance with -mcpu=3Dnative. However reassociation really needs to= be taught about the existence of FMAs.=