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<p><font size="-1">I run the release tests in an Ubuntu VM that I
prepare by building and installing the most recent clang-llvm
version. I also install a fair number of Ubuntu distribution
packages that seemed to be required for building all of the LLVM
distribution from when I was looking at that over a year back.
The used portion of the VM after the clang-llvm build, those two
projects only, that contains the object files is close to 23GB.<br>
</font></p>
<p><font size="-1">Seems like an easy way to put this together would
be to tar the VM and provide it for download. 23GB is certainly
large but some popular video games obtained by download are
larger.</font></p>
<p><font size="-1">Decide what you want and I can build the VM with
the clang projects and upload that.<br>
</font></p>
<p><font size="-1">Neil Nelson</font><br>
</p>
<div class="moz-cite-prefix">On 4/16/21 3:57 AM, via llvm-dev wrote:<br>
</div>
<blockquote type="cite"
cite="mid:AS8P193MB168578D00BCFD41BF1039A32844C9@AS8P193MB1685.EURP193.PROD.OUTLOOK.COM">
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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">A few points:<o:p></o:p></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph"
style="margin-left:0cm;mso-list:l2 level1 lfo4">This doesn't
need to be an official LLVM distribution, it can just be a
thing that is exists in good faith that you can download if
you want but comes with no guarantees of any kind. A
colleague who I was speaking to partially likened it to how
people use Homebrew and install packages compiled by
“someone”. Package managers do implement additional hash
checks, etc. but are not very different from what I am
suggesting.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0cm;mso-list:l2 level1 lfo4">We can leave
it up to the user to make sure that they have the same
version of Clang, Cmake, etc. as the buildbot that compiled
the code (the buildbots can store this information in a text
file and give it to the users). Like I said this would be a
thing that exists with no guarantees of any kind. My idea is
to just give people the resources that they need in order to
contribute to LLVM and cannot get without spending money.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0cm;mso-list:l2 level1 lfo4">While I do
have access to SN-DBS, I’m not talking about myself
personally here. People cannot be expected to have access to
distributed build systems. Most university students for
example will have thin and light ultrabooks that are easy to
carry to lectures and most definitely won’t be able to
compile LLVM from scratch.<o:p></o:p></li>
</ul>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal">Nabeel<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="mso-fareast-language:EN-GB" lang="EN-US">From:</span></b><span
style="mso-fareast-language:EN-GB" lang="EN-US"> Philip
Reames <a class="moz-txt-link-rfc2396E" href="mailto:listmail@philipreames.com"><listmail@philipreames.com></a>
<br>
<b>Sent:</b> 14 April 2021 23:39<br>
<b>To:</b> Alexandre Ganea
<a class="moz-txt-link-rfc2396E" href="mailto:alexandre.ganea@ubisoft.com"><alexandre.ganea@ubisoft.com></a>; Omer, Nabeel
<a class="moz-txt-link-rfc2396E" href="mailto:Nabeel.Omer@sony.com"><Nabeel.Omer@sony.com></a><br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a><br>
<b>Subject:</b> Re: [llvm-dev] Consider making build
directories of the buildbots available<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p>One bit of warning, build trees tend to have relative paths
baked in. From experience, trying to copy an llvm build tree
from one location to another tends to not work well.<o:p></o:p></p>
<p>The best workaround I've seen for this type of thing is to
use docker (or your container format of choice) to construct a
"build image" with the full source and build trees, then
update the source and trigger an (incremental) build.<o:p></o:p></p>
<p>After that's out of the way, you run into two major problems
quickly.<o:p></o:p></p>
<p>1) Such build images tend to be gigantic. (50+gb) Bandwidth
costs, storage costs, and download times add up *quickly*.
<br>
2) Their value as incremental build sources tend to age very
quickly. If you look at the commits to llvm, core headers get
changed shocking often. As such, if you're trying to follow
ToT you quickly end up doing what is effectively a clean build
anyways. The only workflow which "somewhat works" is to
develop against some recent snapshot, then rebase only at the
very last and pay the cost of a full build.<o:p></o:p></p>
<p>I've played enough with ideas like this in the past to
recommend you not go down this path.<o:p></o:p></p>
<p>An alternate approach I recommend - and use personally - is
to do all builds on an AWS instance. With some basic
scripting (<a
href="https://github.com/preames/llvm-aws-builder"
moz-do-not-send="true">here's mine</a>), you can do fast
builds for a couple of dollars a day. I've been working this
was for about 6 months, and have found it dramatically easier
than all the options I played with before.
<o:p></o:p></p>
<p>Philip<o:p></o:p></p>
<div>
<p class="MsoNormal">On 4/14/21 1:53 PM, Alexandre Ganea via
llvm-dev wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal">That’s an interesting idea. There are
several issues to consider:<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<ol style="margin-top:0cm" type="1" start="1">
<li class="MsoListParagraph"
style="margin-left:0cm;mso-list:l1 level1 lfo3">The build
needs to be deterministic, if we want to share .OBJ files
among LLVM developers. In essence, that means fully
implementing [1]. I’m not sure how much of the LLVM
codebase supports that.<br>
Just the toolchain part is challenging to implement. We
would need to ensure all users are using precisely the
same compiler, the same linker, same cmake, same platform
SDKs, etc. in order to expect good cache hits.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0cm;mso-list:l1 level1 lfo3">There’s
the security consideration. If anyone is to pull on the
cached .OBJ files, you need to “trust” these .OBJ files in
the first place. That means maybe restraining the list of
cache “publishers” to the LLVM github group, and signing
the .OBJs with a private key or something along those
lines.<o:p></o:p></li>
<li class="MsoListParagraph"
style="margin-left:0cm;mso-list:l1 level1 lfo3">There’s a
file size consideration. My build folder for only { llvm,
clang, lld } is about 40 GB. When using the ThinLTO cache,
that goes over 100 GB. Still, build artefacts compress
quite well (3:1 at least), and you’d probably pay the
network price only once, then cache hits would be
incremental.<o:p></o:p></li>
</ol>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I think the same idea could apply for
distributing the compilation. It’d be interesting to have a
public LLVM distributed compilation service. But how can we
trust it? Even if we only compile on “trusted” machines,
there’s still a risk of attack. That’s probably why these
caching/remote compilation systems are only used inside an
organization, which can guarantee trust (somehow). Since
you’re at Sony, perhaps you have access to a internal SN-DBS
pool? [2]<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">[1] <a
href="https://blog.llvm.org/2019/11/deterministic-builds-with-clang-and-lld.html"
moz-do-not-send="true">
https://blog.llvm.org/2019/11/deterministic-builds-with-clang-and-lld.html</a><o:p></o:p></p>
<p class="MsoNormal">[2] <a
href="https://www.snsystems.com/tech-blog/2014/01/06/building-with-the-network/"
moz-do-not-send="true">
<span lang="EN-CA">https://www.snsystems.com/tech-blog/2014/01/06/building-with-the-network/</span></a><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="mso-fareast-language:EN-CA" lang="FR">De :</span></b><span
style="mso-fareast-language:EN-CA" lang="FR"> llvm-dev
</span><a href="mailto:llvm-dev-bounces@lists.llvm.org"
moz-do-not-send="true"><span
style="mso-fareast-language:EN-CA" lang="FR"><llvm-dev-bounces@lists.llvm.org></span></a><span
style="mso-fareast-language:EN-CA">
<b><span lang="FR">De la part de</span></b><span
lang="FR"> via llvm-dev<br>
<b>Envoyé :</b> April 14, 2021 3:31 PM<br>
<b>À :</b> </span></span><a
href="mailto:llvm-dev@lists.llvm.org"
moz-do-not-send="true"><span
style="mso-fareast-language:EN-CA" lang="FR">llvm-dev@lists.llvm.org</span></a><span
style="mso-fareast-language:EN-CA" lang="FR"><br>
<b>Objet :</b> Re: [llvm-dev] Consider making build
directories of the buildbots available</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Ah, apologies, I think I wasn’t clear. I
am talking about making object files available in this
manner so that people can download them and compile just
their changes without having to compile all of LLVM, thus
reducing the barrier to entry. As far as I am aware, the
releases on Github do not contain object files.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Nabeel Omer<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="mso-fareast-language:EN-GB" lang="EN-US">From:</span></b><span
style="mso-fareast-language:EN-GB" lang="EN-US">
llvm-dev <</span><a
href="mailto:llvm-dev-bounces@lists.llvm.org"
moz-do-not-send="true"><span
style="mso-fareast-language:EN-GB" lang="EN-US">llvm-dev-bounces@lists.llvm.org</span></a><span
style="mso-fareast-language:EN-GB" lang="EN-US">>
<b>On Behalf Of </b>Neil Nelson via llvm-dev<br>
<b>Sent:</b> 14 April 2021 20:05<br>
<b>To:</b> </span><a
href="mailto:llvm-dev@lists.llvm.org"
moz-do-not-send="true"><span
style="mso-fareast-language:EN-GB" lang="EN-US">llvm-dev@lists.llvm.org</span></a><span
style="mso-fareast-language:EN-GB" lang="EN-US"><br>
<b>Subject:</b> Re: [llvm-dev] Consider making build
directories of the buildbots available</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<p><span style="font-size:10.0pt">Perhaps these pages may
help.</span><o:p></o:p></p>
<p><a href="https://github.com/llvm/llvm-project/releases"
moz-do-not-send="true"><span style="font-size:10.0pt">https://github.com/llvm/llvm-project/releases</span></a><o:p></o:p></p>
<p><a
href="https://github.com/llvm/llvm-project/releases/tag/llvmorg-12.0.0-rc5"
moz-do-not-send="true"><span style="font-size:10.0pt">https://github.com/llvm/llvm-project/releases/tag/llvmorg-12.0.0-rc5</span></a><o:p></o:p></p>
<p><span style="font-size:10.0pt">Neil Nelson</span><o:p></o:p></p>
<div>
<p class="MsoNormal"><span style="font-size:10.0pt">On
4/14/21 12:53 PM, via llvm-dev wrote:</span><o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal">Hi LLVM devs,<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">As you are already aware, performing a
clean build of LLVM requires considerable computing
resources. This presents a barrier to entry for people who
do not have access to large computers. Since the
<span lang="EN-US">buildbots already regularly compile the
LLVM codebase, making tarballs of their build
directories available on a public facing server will
dramatically reduce the barrier to entry. Is this
something that the community is willing to consider?</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US">Thanks,</span><o:p></o:p></p>
<p class="MsoNormal"><span lang="EN-US">Nabeel Omer</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span
style="mso-fareast-language:EN-GB"> </span><o:p></o:p></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>LLVM Developers mailing list<o:p></o:p></pre>
<pre><a href="mailto:llvm-dev@lists.llvm.org" moz-do-not-send="true">llvm-dev@lists.llvm.org</a><o:p></o:p></pre>
<pre><a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev" moz-do-not-send="true">https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a><o:p></o:p></pre>
</blockquote>
<p class="MsoNormal"><span style="mso-fareast-language:EN-GB"><br>
<br>
<o:p></o:p></span></p>
<pre>_______________________________________________<o:p></o:p></pre>
<pre>LLVM Developers mailing list<o:p></o:p></pre>
<pre><a href="mailto:llvm-dev@lists.llvm.org" moz-do-not-send="true">llvm-dev@lists.llvm.org</a><o:p></o:p></pre>
<pre><a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev" moz-do-not-send="true">https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev</a><o:p></o:p></pre>
</blockquote>
</div>
<br>
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<pre class="moz-quote-pre" wrap="">_______________________________________________
LLVM Developers mailing list
<a class="moz-txt-link-abbreviated" href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>
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