From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id E1DD43858D32; Sun, 28 Jan 2024 17:26:24 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E1DD43858D32 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1706462784; bh=wm28kL4vM6qRljXZj+CEk/KiR6oAu7iEdQ9ojkxzTwU=; h=From:To:Subject:Date:From; b=DnwBbJKslKhPw+POQlDGSaen0RvkOU4XL5gyRuEgTlDVbecB95vTFXxzd/0C8V0Tn anjm3qNRPfsXzGYIYX4djPfooE+Gni5u3yeWZEQ7r7K0J6N8bNkahDkAZStE6Jn9Mi FT/gW+y54nX9/W1zN0RQ+eGbsUh4LY2DgRwspvXo= From: "jamborm at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/113641] New: 510.parest_r with PGO at O2 slower than GCC 12 (7% on Zen 3&2, 4% on CascadeLake) since r13-4272-g8caf155a3d6e23 Date: Sun, 28 Jan 2024 17:26:24 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Version: 14.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: jamborm at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status bug_severity priority component assigned_to reporter blocked target_milestone cf_gcchost cf_gcctarget Message-ID: 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=3D113641 Bug ID: 113641 Summary: 510.parest_r with PGO at O2 slower than GCC 12 (7% on Zen 3&2, 4% on CascadeLake) since r13-4272-g8caf155a3d6e23 Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: jamborm at gcc dot gnu.org Blocks: 26163 Target Milestone: --- Host: x86_64-linux-gnu Target: x86_64-linux-gnu During the development of GCC 13, 510.parest_r run-time regressed on x86_64 when built with profile guided optimization and just plain O2 and master th= an when using GCC12. The difference is not big but fairly clear cut, about 7.= 6% on Zen3: https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=3D740.457.0&plot.1= =3D892.457.0&plot.2=3D694.457.0& and about 7.2% on Zen2: https://lnt.opensuse.org/db_default/v4/SPEC/graph?plot.0=3D777.457.0&plot.1= =3D932.457.0&plot.2=3D687.457.0& The graphs above show use of both LTO and PGO but LTO is not necessary. I was able to bisect the regression to commit r13-4272-g8caf155a3d6e23 (i38= 6: Only enable small loop unrolling in backend [PR 107692]). parest_r is also about 4% slower when compiled with this revision than with the previous one= on Intel CascadeLake. Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D26163 [Bug 26163] [meta-bug] missed optimization in SPEC (2k17, 2k and 2k6 and 95= )=