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

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.

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> wrote:
> On Sat, Apr 18, 2020 at 7:43 PM Fangrui Song via cfe-dev <
> 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
>> 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 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
>> I will delete that as a follow-up.
>>
>
> AFAIK aligned bundling has other users (e.g. the author of
> 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
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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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.


On Mon, Apr 20, 2020 at 4:22 PM Derek Schuff via llvm-dev <
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.
>
> 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> wrote:
>
>> On Sat, Apr 18, 2020 at 7:43 PM Fangrui Song via cfe-dev <
>> 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
>>> 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 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
>>> I will delete that as a follow-up.
>>>
>>
>> AFAIK aligned bundling has other users (e.g. the author of
>> 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
>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>
>> _______________________________________________
>> LLVM Developers mailing list
>> 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
>
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We do not plan to do a full NaCl toolchain release. Instead there is a
smaller component that's only used as part of the Chrome build (which
builds a sandboxed runtime component from code in the Chromium codebase),
which only needs to support a subset of the codegen functionality. The
amount of NaCl code upstream is not actually that large; but it is largely
parts that are harder to keep out-of-tree patches for.

On Mon, Apr 20, 2020 at 1:48 PM James Y Knight <jyknight at google.com>
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.
>
>
> On Mon, Apr 20, 2020 at 4:22 PM Derek Schuff via llvm-dev <
> 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.
>>
>> 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> wrote:
>>
>>> On Sat, Apr 18, 2020 at 7:43 PM Fangrui Song via cfe-dev <
>>> 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
>>>> 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 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
>>>> I will delete that as a follow-up.
>>>>
>>>
>>> AFAIK aligned bundling has other users (e.g. the author of
>>> 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
>>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev
>>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> 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
>>
>
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> 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
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