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<div class="moz-cite-prefix">On 10/25/2017 12:10 PM, Evgeny
Astigeevich via llvm-dev wrote:<br>
</div>
<blockquote cite="mid:E77435FE-6FA6-4DF9-B495-2F8EEBE0E785@arm.com"
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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Hi
Chandler,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I
ran the LNT benchmarks and SPEC2k6.train on AArch64
Cortex-A57. I used revisions: Clang 316561, LLVM 316563.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Options:
-O3 -mcpu=cortex-a57 -fomit-frame-pointer
-fexperimental-new-pass-manager<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Regressions:
execution time increase<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">LNT<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/FreeBench/fourinarow/fourinarow
1018.58%</span></p>
</div>
</blockquote>
<br>
How real is this?<br>
<br>
-Hal<br>
<br>
<blockquote cite="mid:E77435FE-6FA6-4DF9-B495-2F8EEBE0E785@arm.com"
type="cite">
<div class="WordSection1">
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/Fhourstones/fhourstones
9.06%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/Ptrdist/yacr2/yacr2
7.23%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/Olden/perimeter/perimeter
6.87%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/MiBench/consumer-typeset/consumer-typeset
6.02%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/Trimaran/enc-pc1/enc-pc1
5.59%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/ASC_Sequoia/AMGmk/AMGmk
5.03%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">SPEC2k6<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">453.povray
17.11%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">482.sphinx3
3.44%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">444.namd
2.89%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Improvements:
execution time decrease<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">LNT<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/BitBench/uudecode/uudecode
-50.90%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">SingleSource/Benchmarks/Adobe-C++/loop_unroll
-27.75%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">SingleSource/Benchmarks/Misc/perlin
-21.35%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/Olden/em3d/em3d
-19.12%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/tramp3d-v4/tramp3d-v4
-8.58%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">SingleSource/Benchmarks/McGill/chomp
-6.33%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/sim/sim
-5.41%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Applications/ClamAV/clamscan
-3.11%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">MultiSource/Benchmarks/TSVC/Symbolics-dbl/Symbolics-dbl
-2.81%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">SPEC2k6<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">429.mcf
-5.18%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">473.astar
-2.65%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">400.perlbench
-1.90%<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">There
are also code sizes increases/decreases. The maximum
increase is 18.98%. The maximum decrease is 25.65%.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Evgeny
Astigeevich<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span
style="font-size:12.0pt;color:black">From: </span></b><span
style="font-size:12.0pt;color:black">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
Chandler Carruth via llvm-dev
<a class="moz-txt-link-rfc2396E" href="mailto:llvm-dev@lists.llvm.org"><llvm-dev@lists.llvm.org></a><br>
<b>Reply-To: </b>Chandler Carruth
<a class="moz-txt-link-rfc2396E" href="mailto:chandlerc@gmail.com"><chandlerc@gmail.com></a><br>
<b>Date: </b>Wednesday, 18 October 2017 at 07:51<br>
<b>To: </b>llvm-dev <a class="moz-txt-link-rfc2396E" href="mailto:llvm-dev@lists.llvm.org"><llvm-dev@lists.llvm.org></a><br>
<b>Subject: </b>[llvm-dev] RFC: Switching to the new pass
manager by default<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Greetings everyone! <o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">The new pass manager is getting
extremely close to the point where I'm not aware of any
significant outstanding work needed, and I'd like to see
what else would be needed to enable it by default. Here
are the current functionality I'm aware of outstanding:<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">1) Does not do non-trivial loop
unswitching. Majority of this is in
<a moz-do-not-send="true"
href="https://reviews.llvm.org/D34200">https://reviews.llvm.org/D34200</a> but
will need one or two small follow-ups.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">2) Currently, sanitizers don't work
correctly with it. Thanks to the work of others, the
missing infrastructure has been added and I'll send a
patch to wire this up this week.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">3) Missing support for 'optnone'. I've
been working on this, but the existing testing wasn't as
thorough as I wanted, so it is going slowly. I've got
about 1/4 of this implemented and should have patches this
week or next.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">4) Missing opt-bisect (or similar)
facility. This looks pretty trivial to add, but I've not
even started. If anyone is interested in it, go for it. We
might even be able to do something simpler using the
generic debug counters and get equivalent functionality.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">... that's it?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Optimization quality / run-time
performance:<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">- We've been using it at Google
extensively and are very happy with the optimization
quality. Benchmarks look *very* good here.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">- More data from other users would be
important.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">- You can try it out with
`-fexperimental-new-pass-manager` to Clang<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Compile-time performance:<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">- Sometimes *much* better due to cached
analyses.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">- Sometimes worse, typically due to
more / different inlining in turn running main pipeline
(GVN + InstCombine) more times or over more code.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">- Overall somewhat a wash, but the
increased compile times typically due to the optimizer
"trying" harder, so not too concerning on our end.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal">- Again, more feedback from other users
good: `-fexperimental-new-pass-manager` to Clang<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Once the four missing things land, I'll
also happily work on collecting some of the basics on the
test-suite and CTMark. But I suspect more "in the wild"
data would really be useful here given the significance of
the change.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Thoughts? What else (beyond the four
items above and feedback on run-time and compile-time)
would folks like to see?<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">Once this happens, I'll also be
preparing some batch, mechanical updates to the test suite
to primarily use the new pass manager. Also there is lots
of documentation updates that will be needed here.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">-Chandler<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">PS: I'll be sending a note to cfe-dev
as a "heads up" about this discussion as in some ways, the
default flip is mostly a Clang default flip. But hopefully
our doc updates will trigger this being "perceived" as the
default for other frontends, and I'll try to reach out to
other major frontends as well (Swift and Rust are on my
radar, and I've already started talking with Philip Reames
about their Falcon JIT).<o:p></o:p></p>
</div>
</div>
</div>
<br>
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<br>
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</pre>
</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory</pre>
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