From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 97624C624DB for ; Sat, 5 Sep 2026 13:26:18 +0000 (UTC) Subject: Re: [PATCH 00/11] clang/llvm: Upgrade to 23.1.0 To: openembedded-core@lists.openembedded.org From: "Dora, Sunil Kumar" X-Originating-Location: Bengaluru, Karnataka, IN (106.51.216.172) X-Originating-Platform: Windows Chrome 151 User-Agent: GROUPS.IO Web Poster MIME-Version: 1.0 Date: Sat, 05 Sep 2026 06:26:09 -0700 References: <20260830125853.1139807-1-sunilkumar.dora@windriver.com> <964.1788497355893282310@lists.openembedded.org> In-Reply-To: <964.1788497355893282310@lists.openembedded.org> Message-ID: <135420.1788614769564017900@lists.openembedded.org> Content-Type: multipart/alternative; boundary="a7d8zy3PpE21NHAowBHj" List-Id: X-Webhook-Received: from 45-33-107-173.ip.linodeusercontent.com [45.33.107.173] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Sat, 05 Sep 2026 13:26:18 -0000 X-Groupsio-URL: https://lists.openembedded.org/g/openembedded-core/message/245148 --a7d8zy3PpE21NHAowBHj Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Fri, Sep 4, 2026 at 10:19 AM, Dora, Sunil Kumar wrote: >=20 > I am reducing a testcase and will report it to llvm, will post the link > here. > If a fix lands I will request a release/23.x backport. Hi Khem, I bisected llvm between 22.1.8 and 23.1.0. The problem comes from the new D= FAJumpThreading pass which is on by default in clang 23. The full file takes more than 90 minute= s where clang 22 needs about 2 seconds. I reported it upstream with a reduced testcase: https://github.com/llvm/llvm-project/issues/221391 There is also a better workaround than the -disable-lsr I posted earlier. T= urning off just the new pass keeps LSR and behaves the same as clang 22: CFLAGS:append:toolchain-clang =3D " -mllvm -enable-dfa-jump-thread=3Dfalse" I sent this as v2 of your dovecot patch on openembedded-devel. Once the llv= m fix lands I will ask for a release/23.x backport, then we can drop the workaround. Thanks, Sunil Dora --a7d8zy3PpE21NHAowBHj Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable
On Fri, Sep 4, 2026 at 10:19 AM, Dora, Sunil Kumar wrote:
I am reducing a testcase and will report it to llvm, will post = the link here.
If a fix lands I will request a release/23.x backport.=
Hi Khem,

I bisected llvm between 22.1.8 and 23.1.0. The problem = comes from the new DFAJumpThreading pass
which is on by default in cl= ang 23. The full file takes more than 90 minutes where clang 22 needs about=
2 seconds.

I reported it upstream with a reduced testcase= :
https://github.com/llvm/llvm-project/issues/221391

There = is also a better workaround than the -disable-lsr I posted earlier. Turning= off just the new pass keeps
LSR and behaves the same as clang 22:
CFLAGS:append:toolchain-clang =3D " -mllvm -enable-dfa-jump-thread= =3Dfalse"

I sent this as v2 of your dovecot patch on openembedde= d-devel. Once the llvm fix lands I will ask for a
release/23.x backpo= rt, then we can drop the workaround.

Thanks,
Sunil Dora

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