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<p>All code requires maintenance. Additional users of existing API
tends to limit their evolution. If there is not a community
around a particular portion of code, that code is purely a drag on
the project and community as a whole. We have a strong
expectation that contributors "pay their way" in maintenance
costs. At a minimum, new code must be net neutral from the
communities perspective. This is a fairly high bar to clear in
practice. <br>
</p>
<p><br>
</p>
<p>(All of the above is generic and not specific to this particular
proposal, but does address the specific question below.)</p>
<p><br>
</p>
<br>
<div class="moz-cite-prefix">On 03/08/2018 04:30 AM, Neil Hickey via
llvm-dev wrote:<br>
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<div style="color: rgb(0, 0, 0);">Thanks for your feedback
Philip. Could you perhaps explain what the downsides to LLVM
are of accepting this as a subproject as I can't really see
any myself.
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<p style="margin-top:0; margin-bottom:0">Neil<br>
</p>
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<div id="x_divRplyFwdMsg" dir="ltr"><font
style="font-size:11pt" face="Calibri, sans-serif"
color="#000000"><b>From:</b> llvm-dev
<a class="moz-txt-link-rfc2396E" href="mailto:llvm-dev-bounces@lists.llvm.org"><llvm-dev-bounces@lists.llvm.org></a> on behalf of
Philip Reames via llvm-dev
<a class="moz-txt-link-rfc2396E" href="mailto:llvm-dev@lists.llvm.org"><llvm-dev@lists.llvm.org></a><br>
<b>Sent:</b> 06 March 2018 23:07:54<br>
<b>To:</b> Anastasia Stulova; Chris Lattner<br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>; nd; Tomeu Vizoso<br>
<b>Subject:</b> Re: [llvm-dev] SPIRV-LLVM as an external
tool</font>
<div> </div>
</div>
<div style="background-color:#FFFFFF">
<p>I've only been skimming the discussion thread so far,
but so far, I see no strong reason for this to be a LLVM
subproject in it's current form. I would recommend
pursing a standalone open source project, building a
community around the common development, and then return
to this proposal once there is an existing community
around an existing codebase. Until that time, I see
lots of downside for LLVM in accepting this project and
little benefit.
<br>
</p>
<p><br>
</p>
<p>Philip<br>
</p>
<br>
<div class="x_x_moz-cite-prefix">On 03/06/2018 10:54 AM,
Anastasia Stulova via llvm-dev wrote:<br>
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<p style="margin-top:0; margin-bottom:0">Hi Chris,</p>
<p style="margin-top:0; margin-bottom:0"><br>
</p>
<p style="margin-top:0; margin-bottom:0">The main
benefit for LLVM to include SPIRV support directly
is to increase the number of users and developers in
the area of heterogeneous computing, e.g. GPUs,
FPGAs, DSPs.
<br>
</p>
<p style="margin-top:0; margin-bottom:0"><br>
</p>
<p style="margin-top:0; margin-bottom:0">We want to
increase the number of such devices that LLVM
natively supports by adding compilation to SPIRV due
to the shortage of proprietary backends in upstream
LLVM.<br>
</p>
<br>
Just to clarify we are currently suggesting to
integrate the converter as a subproject of LLVM,
similar to Clang or libclc, to reduce the overhead for
the overall community in maintaining it and running
tests.
<p style="margin-top:0; margin-bottom:0"><br>
</p>
<p style="margin-top:0; margin-bottom:0">One more
thing to be mentioned, the latest OpenCL standards
evolve towards off-line compilation from OpenCL C++
to SPIRV. So having SPIRV generation directly in
LLVM would allow us to deliver fully complete and
compliant OpenCL C++ support, without using any
external tools. See discussion with Tom earlier.<span></span></p>
<p style="margin-top:0; margin-bottom:0"><br>
</p>
<p style="margin-top:0; margin-bottom:0">Thanks!</p>
<p style="margin-top:0; margin-bottom:0">Anastasia<br>
</p>
<br>
<br>
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<div id="x_x_divRplyFwdMsg" dir="ltr"><font
style="font-size:11pt" face="Calibri,
sans-serif" color="#000000"><b>From:</b> Chris
Lattner
<a class="x_x_moz-txt-link-rfc2396E"
href="mailto:clattner@nondot.org"
moz-do-not-send="true"><clattner@nondot.org></a><br>
<b>Sent:</b> 01 March 2018 01:52<br>
<b>To:</b> <a
class="x_x_moz-txt-link-abbreviated"
href="mailto:tstellar@redhat.com"
moz-do-not-send="true">
tstellar@redhat.com</a><br>
<b>Cc:</b> Anastasia Stulova; Tomeu Vizoso; <a
class="x_x_moz-txt-link-abbreviated"
href="mailto:llvm-dev@lists.llvm.org"
moz-do-not-send="true">
llvm-dev@lists.llvm.org</a>; nd<br>
<b>Subject:</b> Re: [llvm-dev] SPIRV-LLVM as an
external tool</font>
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<div class="x_x_BodyFragment"><font size="2"><span
style="font-size:11pt">
<div class="x_x_PlainText">On Feb 27, 2018, at
10:25 AM, Tom Stellard via llvm-dev
<a class="x_x_moz-txt-link-rfc2396E"
href="mailto:llvm-dev@lists.llvm.org"
moz-do-not-send="true"><llvm-dev@lists.llvm.org></a>
wrote:<br>
> On 02/27/2018 05:07 AM, Anastasia
Stulova wrote:<br>
>>> SPIR-V does not have to be a
part of LLVM for you to do this. You can
add<br>
>>> the SPIR-V target to clang and
then define a SPIR-V toolchain (i.e.
clang/Driver/Toolchains)<br>
>>> that uses the external tool to
translate LLVM IR to SPIR-V.<br>
>> <br>
>> <br>
>> Ok. I guess if Clang community
accepts this way, it would be better to set
up the SPIRV converter as a tool of LLVM.<br>
>> <br>
>> So the question is are there any
downsides of this? Or would anyone object if
we add the converter to the LLVM project as
an optional tool? We would of course take
care of configuring and maintaining it
ourselves.<br>
> <br>
> There is no requirement that the tool
needs to be an official part of the LLVM<br>
> project to implement to use it this
way For example, the cuda toolchain<br>
> in clang relies on a few proprietary
tools from NVIDIA.<br>
> <br>
> I think too much emphasis is being
placed on having this tool be part of the<br>
> LLVM project.<br>
<br>
Agreed. Why is it good for LLVM to include
this tool?<br>
<br>
If there was a strong rationale for doing
so, it would probably make sense to be a new
subproject of some sort rather than included
in the main llvm repo (not sure if that is
what was being proposed).<br>
<br>
-Chris<br>
<br>
<br>
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