[Release-testers] [lldb-dev] [3.8 Release] Release status

Hal Finkel via Release-testers release-testers at lists.llvm.org
Fri Feb 19 09:15:27 PST 2016

----- Original Message -----
> From: "Renato Golin" <renato.golin at linaro.org>
> To: "Hans Wennborg" <hans at chromium.org>
> Cc: "llvm-dev" <llvm-dev at lists.llvm.org>, "cfe-dev" <cfe-dev at lists.llvm.org>, "LLDB Dev" <lldb-dev at lists.llvm.org>,
> "openmp-dev (openmp-dev at lists.llvm.org)" <openmp-dev at lists.llvm.org>, release-testers at lists.llvm.org, "Cong Hou"
> <congh at google.com>, "Davide Italiano" <davide at freebsd.org>, "Quentin Colombet" <qcolombet at apple.com>, "Hal Finkel"
> <hfinkel at anl.gov>, "Chandler Carruth" <chandlerc at google.com>, "JF Bastien" <jfb at google.com>, "Nemanja Ivanovic"
> <nemanja.i.ibm at gmail.com>, "Matthias Braun" <matze at braunis.de>
> Sent: Friday, February 19, 2016 9:33:16 AM
> Subject: Re: [lldb-dev] [3.8 Release] Release status
> On 19 February 2016 at 00:22, Hans Wennborg via lldb-dev
> <lldb-dev at lists.llvm.org> wrote:
> > - PR26600: Loop vectorization creates an unsafe out-of-bounds load
> >   There's a patch out: http://reviews.llvm.org/D17332
> >   But no comments yet.. Hal?
> This looks like a serious bug but Hal's idea is still unproven.

I feel your statement misrepresents my review of the patch. What I said in the review was:

[from review]
How complicated would it be, instead of bailing out when we have a group without the last member, to peel off the last vector iteration instead (i.e. jump to the scalar tail loop one vector-loop iteration "early")?

It seems like that would be a better solution (although, if you agree, but it seems too complicated to implement for the release branch, I'm fine with taking this (and pulling it into the release branch), and then implementing the better solution in trunk only).
[end from review]

What we have now is one easy fix, and I simply asked if we could get a much better easy fix in short order (i.e. for 3.8.0). Regardless, I feel I was quite clear in the review that this fix is otherwise fine, and we definitely need something for 3.8.0. It is a serious bug.

Thanks again,

> I
> think we should land the patch as it is, since it disables the bad
> behaviour, and think about a fix later. Depending on how complex the
> fix is, we might not even merge it into 3.8.x later on, but we need
> the fix in 3.8.0.
> > - ARM: fix VFP asm constraints: http://reviews.llvm.org/D17349
> >   It's not a regression, but I'll take it if it lands real soon.
> No brainer. Accepted on trunk by compnerd, I'll merge into release_38
> shortly.
> cheers,
> --renato

Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory

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