From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id 485C7388E81A; Tue, 23 Feb 2021 17:59:43 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 485C7388E81A
From: "jamborm at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/99083] Big run-time regressions of 519.lbm_r with LTO
Date: Tue, 23 Feb 2021 17:59:43 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: missed-optimization, ra
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jamborm at gcc dot gnu.org
X-Bugzilla-Status: RESOLVED
X-Bugzilla-Resolution: FIXED
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 11.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-99083-4-5YsBBVHuAz@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-99083-4@http.gcc.gnu.org/bugzilla/>
References: <bug-99083-4@http.gcc.gnu.org/bugzilla/>
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
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Tue, 23 Feb 2021 17:59:43 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99083

--- Comment #12 from Martin Jambor <jamborm at gcc dot gnu.org> ---
For the record, I have benchmarked the patches from comment #4 and comment =
#10
on top of commit 6b1633378b7 (for which I already have unpatched benchmark
results) and the regression of 519.lbm_r compiled with -O2 LTO dropped from=
 62%
to 8%.=20=20

The -Ofast -march=3Dnative -flto vs. non-LTO regression also dropped from 8=
% to
about 5% (GCC 10 also has non-LTO 2.5% faster than LTO, but at least both t=
imes
improved vs. GCC 10).

The only notable regression brought about the patch was 538.imagick_r when
compiled at -Ofast -march=3Dnative without LTO, which was 6% slower with the
patch.

All of the measurements were done on a Zen2 machine.

Thank you for reverting the patch, now we need to look for LNT to pick up t=
he
changes.=