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<div class="moz-cite-prefix">On 12/21/2016 01:11 PM, Sean Silva via
llvm-dev wrote:<br>
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cite="mid:CAHnXoan9hhyGJ7f=3sPc8fJTDGOnzi_73yNSHDHaRnp71OxLbQ@mail.gmail.com"
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<div class="gmail_quote">On Wed, Dec 21, 2016 at 8:07 AM,
Davide Italiano via llvm-dev <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex"><span class="gmail-">On
Mon, Dec 19, 2016 at 4:24 PM, Mikhail Zolotukhin<br>
<<a moz-do-not-send="true"
href="mailto:mzolotukhin@apple.com">mzolotukhin@apple.com</a>>
wrote:<br>
> Hi Davide,<br>
><br>
> Thanks for the analysis, it's really interesting!
And I'm really glad that we now put more and more
attention at the compile time!<br>
><br>
> Just recently I've been looking into historical
compile time data as well, and have had similar
conclusions. The regressions you've found are probably
caused by:<br>
> 1) r289813 and r289855 - new matchers in
InstCombine<br>
> 2) r286814 and r288024 - changes in Inlining cost
model<br>
><br>
<br>
</span>Haven't looked at 2) yet, but I can confirm for 1).
Sanjay/Ehsan, can<br>
you please explain what's the motivation behind the new<br>
transformations you introduced? I'm tempted to ask a
revert, but I'd<br>
like to understand the motivations first.<br>
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<div>Both r289813 and r289855 add a very small amount of
matching (it seems?) compared to the rest of the size of
instcombine. How is it that these checks are causing such
a disproportionate slowdown compared to the rest of
instcombine? (by "I can confirm for 1)" I assume you mean
these two patches have a pretty significant impact on
compile time; not "0.1%" each)</div>
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<br>
<a class="moz-txt-link-freetext" href="https://llvm.org/bugs/show_bug.cgi?id=31449">https://llvm.org/bugs/show_bug.cgi?id=31449</a> - it seems that r289813
also is causing a miscompile.<br>
<br>
-Hal<br>
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<div>-- Sean Silva</div>
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<div class="gmail-HOEnZb">
<div class="gmail-h5"><br>
--<br>
Davide<br>
<br>
"There are no solved problems; there are only problems
that are more<br>
or less solved" -- Henri Poincare<br>
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<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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