llvm dev - Apr 2020 - [cfe-dev] State of NaCl in monorepo?

> On Apr 20, 2020, at 1:47 PM, James Y Knight via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> But the most recent NaCL toolchain release is based on LLVM 3.7 from 2015.
> 
> Unless you're planning to upgrade the NaCL toolchain to use a new
release based on LLVM devhead (which would seem a rather expensive thing to
attempt now, given the plan to desupport it in a year), I don't think
keeping the code in LLVM is actually useful for anyone at this point.
Right, I think this is the key issue.  If the community cannot use the code that
is in tree, there isn’t a strong reason for the community to maintain it.

-Chris
> 
> 
> On Mon, Apr 20, 2020 at 4:22 PM Derek Schuff via llvm-dev <llvm-dev at
lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> Hi Fangrui,
> As you noted we are working on helping our NaCl users transition to
WebAssembly and new web APIs that cover the functionality offered by NaCl. In
terms of actually turning down the platform features, we recently announced a
timeline at
https://blog.chromium.org/2020/01/moving-forward-from-chrome-apps.html
<https://blog.chromium.org/2020/01/moving-forward-from-chrome-apps.html>.
> 
> In terms of LLM, I would prefer to keep the support we have in the tree
until we complete the turndown as long as the support isn't unusually
onerous. Not all of our NaCl toolchain code is upstream, but we are actually
about to redo part of our current downstream code soon to improve Chromium's
C++ support until we complete the platform turndown. And of course we continue
to be available to support it upstream as needed, especially if there is some
particular problem you're looking to solve by removing this code.
> Feel free to contact me directly as well (aside from the usual channels
like this list of course) if you want more on NaCl or PNaCl.
> 
> 
> On Sat, Apr 18, 2020 at 10:25 PM Petr Hosek via llvm-dev <llvm-dev at
lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
> On Sat, Apr 18, 2020 at 7:43 PM Fangrui Song via cfe-dev <cfe-dev at
lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
> Hi all,
> 
> LLVM/Clang supports an OS called 'NaCl'
(llvm/include/llvm/ADT/Triple.h).
> It apparently hasn't had any development since 2015.
> 
> This page https://developer.chrome.com/native-client/migration
<https://developer.chrome.com/native-client/migration>
> mentions that NaCl is deprecated.
> 
> Is it still used? If not, I would propose that we remove it.
> I created a patch https://reviews.llvm.org/D78441
<https://reviews.llvm.org/D78441> which I think can
> delete 90% of the related code.
> 
> There are still a few references left (noticeably aligned bundling in
> MC)
https://sites.google.com/a/chromium.org/dev/nativeclient/pnacl/aligned-bundling-support-in-llvm
<https://sites.google.com/a/chromium.org/dev/nativeclient/pnacl/aligned-bundling-support-in-llvm>
> I will delete that as a follow-up.
> 
> AFAIK aligned bundling has other users (e.g. the author of
https://reviews.llvm.org/D19924 <https://reviews.llvm.org/D19924>
mentioned interested in using bundle locked groups for Hexagon) so its removal
should be probably treated as a separate proposal.
>  
> _______________________________________________
> cfe-dev mailing list
> cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>
> https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
<https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20200420/7f2b11ba/attachment.html>

> On Apr 20, 2020, at 4:32 PM, Chris Lattner via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> 
> 
>> On Apr 20, 2020, at 1:47 PM, James Y Knight via llvm-dev <llvm-dev
at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
>> 
>> But the most recent NaCL toolchain release is based on LLVM 3.7 from
2015.
>> 
>> Unless you're planning to upgrade the NaCL toolchain to use a new
release based on LLVM devhead (which would seem a rather expensive thing to
attempt now, given the plan to desupport it in a year), I don't think
keeping the code in LLVM is actually useful for anyone at this point.
> 
> Right, I think this is the key issue.  If the community cannot use the code
that is in tree, there isn’t a strong reason for the community to maintain it.
IIUC, Derek is saying that a build of Chrome uses the limited NaCl support, but
they plan to stop this on June 2021. It’s therefore usable in a limited manner,
and I don’t think there's much of a cost to the LLVM community if we leave
in until June 2021. Keeping it in likely makes his life easier because they
don’t need to maintain downstream patches while the turn NaCl down. I imagine
that Derek has already implicitly signed up for this maintenance, if ever is
required, as well as for the removal in June 2021.

I see ~zero cost, and upsides for Derek’s team, in keeping this for now.

> -Chris
> 
>> 
>> 
>> On Mon, Apr 20, 2020 at 4:22 PM Derek Schuff via llvm-dev <llvm-dev
at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
>> Hi Fangrui,
>> As you noted we are working on helping our NaCl users transition to
WebAssembly and new web APIs that cover the functionality offered by NaCl. In
terms of actually turning down the platform features, we recently announced a
timeline at
https://blog.chromium.org/2020/01/moving-forward-from-chrome-apps.html
<https://blog.chromium.org/2020/01/moving-forward-from-chrome-apps.html>.
>> 
>> In terms of LLM, I would prefer to keep the support we have in the tree
until we complete the turndown as long as the support isn't unusually
onerous. Not all of our NaCl toolchain code is upstream, but we are actually
about to redo part of our current downstream code soon to improve Chromium's
C++ support until we complete the platform turndown. And of course we continue
to be available to support it upstream as needed, especially if there is some
particular problem you're looking to solve by removing this code.
>> Feel free to contact me directly as well (aside from the usual channels
like this list of course) if you want more on NaCl or PNaCl.
>> 
>> 
>> On Sat, Apr 18, 2020 at 10:25 PM Petr Hosek via llvm-dev <llvm-dev
at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
>> On Sat, Apr 18, 2020 at 7:43 PM Fangrui Song via cfe-dev <cfe-dev at
lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
>> Hi all,
>> 
>> LLVM/Clang supports an OS called 'NaCl'
(llvm/include/llvm/ADT/Triple.h).
>> It apparently hasn't had any development since 2015.
>> 
>> This page https://developer.chrome.com/native-client/migration
<https://developer.chrome.com/native-client/migration>
>> mentions that NaCl is deprecated.
>> 
>> Is it still used? If not, I would propose that we remove it.
>> I created a patch https://reviews.llvm.org/D78441
<https://reviews.llvm.org/D78441> which I think can
>> delete 90% of the related code.
>> 
>> There are still a few references left (noticeably aligned bundling in
>> MC)
https://sites.google.com/a/chromium.org/dev/nativeclient/pnacl/aligned-bundling-support-in-llvm
<https://sites.google.com/a/chromium.org/dev/nativeclient/pnacl/aligned-bundling-support-in-llvm>
>> I will delete that as a follow-up.
>> 
>> AFAIK aligned bundling has other users (e.g. the author of
https://reviews.llvm.org/D19924 <https://reviews.llvm.org/D19924>
mentioned interested in using bundle locked groups for Hexagon) so its removal
should be probably treated as a separate proposal.
>>  
>> _______________________________________________
>> cfe-dev mailing list
>> cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
<https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
<https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> 
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20200420/fa1994e3/attachment.html>

>
>
> IIUC, Derek is saying that a build of Chrome uses the limited NaCl
> support, but they plan to stop this on June 2021. It’s therefore usable in
> a limited manner,
>
Yes, all the official Chrome builds use it, or will soon.

> and I don’t think there's much of a cost to the LLVM community if we
leave
> in until June 2021. Keeping it in likely makes his life easier because they
> don’t need to maintain downstream patches while the turn NaCl down. I
> imagine that Derek has already implicitly signed up for this maintenance,
> if ever is required, as well as for the removal in June 2021.
>
Yes, exactly.

>
> I see ~zero cost, and upsides for Derek’s team, in keeping this for now.
>
>
There are also some pieces that are specific to PNaCl (the portable subset)
rather than NaCl that we can remove right away if folks want that.
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20200421/8936db12/attachment.html>