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Hi Dibyendu,<br>
<br>
All I have at this point is llvm test-suite. I also have access to
SPEC'06, which may be helpful as well. My hope is that the
applications in those benchmarks are complex enough to put enough
pressure on cfl-aa.<br>
<br>
That being said, I'm not an expert in performance testing, and I am
open to suggestions on this topic.<br>
<br>
<div class="moz-cite-prefix">On 05/12/2016 11:53 PM, Das, Dibyendu
wrote:<br>
</div>
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<div class="WordSection1">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi
Jia-<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">What
apps/benchmarks do you plan to use to test the performance
of cfl-aa ?<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">-Dibyendu<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif">
llvm-dev [<a class="moz-txt-link-freetext" href="mailto:llvm-dev-bounces@lists.llvm.org">mailto:llvm-dev-bounces@lists.llvm.org</a>]
<b>On Behalf Of </b>George Burgess IV via llvm-dev<br>
<b>Sent:</b> Thursday, May 12, 2016 11:16 PM<br>
<b>To:</b> James Molloy <a class="moz-txt-link-rfc2396E" href="mailto:james@jamesmolloy.co.uk"><james@jamesmolloy.co.uk></a><br>
<b>Cc:</b> llvm-dev <a class="moz-txt-link-rfc2396E" href="mailto:llvm-dev@lists.llvm.org"><llvm-dev@lists.llvm.org></a>; Jia
Chen <a class="moz-txt-link-rfc2396E" href="mailto:jchen@cs.utexas.edu"><jchen@cs.utexas.edu></a><br>
<b>Subject:</b> Re: [llvm-dev] [GSoC 2016] Introduction
& Feedback - Better Alias Analysis<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">> <span style="font-size:9.5pt">What's
the magic rune to enable cfl-aa?</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">We have two magical opt flags:
-use-cfl-aa and -use-cfl-aa-in-codegen :)<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">IIRC, both of them should cause CFLAA
to be enabled as a last resort.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">On Thu, May 12, 2016 at 12:38 AM,
Daniel Berlin <<a moz-do-not-send="true"
href="mailto:dberlin@dberlin.org" target="_blank">dberlin@dberlin.org</a>>
wrote:<o:p></o:p></p>
<blockquote style="border:none;border-left:solid #CCCCCC
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6.0pt;margin-left:4.8pt;margin-right:0in">
<div>
<p class="MsoNormal">(Just to note: the other issue i
remember with CFL-AA is that it currently causes
performance loss. This is quite common when you
increase precision, because things move/change
things they couldn't before, and often do so without
the natural bounds imprecision provided before :P)<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
<div>
<div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">On Thu, May 12, 2016 at
12:29 AM, James Molloy via llvm-dev <<a
moz-do-not-send="true"
href="mailto:llvm-dev@lists.llvm.org"
target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a></a>>
wrote:<o:p></o:p></p>
<blockquote style="border:none;border-left:solid
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6.0pt;margin-left:4.8pt;margin-right:0in">
<div>
<p class="MsoNormal">Yep, same. What's the
magic rune to enable cfl-aa?<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">James<o:p></o:p></p>
</div>
</div>
<div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<div>
<p class="MsoNormal">On Thu, 12 May
2016 at 05:58 Philip Reames via
llvm-dev <<a
moz-do-not-send="true"
href="mailto:llvm-dev@lists.llvm.org"
target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a></a>>
wrote:<o:p></o:p></p>
</div>
<blockquote
style="border:none;border-left:solid
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<div>
<div>
<p class="MsoNormal">On 05/11/2016
05:16 PM, George Burgess IV via
llvm-dev wrote:<o:p></o:p></p>
</div>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<p class="MsoNormal">> <span
style="font-size:9.5pt">After
applying the patch on
r267335 and bootstrap
LLVM/clang with cfl-aa
enabled on its own as well
as behind basic-aa on an
x86 machine, I ran
test-suite with lit and
saw no failed test cases</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:9.5pt">Woohoo!
This is great news. :D</span><o:p></o:p></p>
</div>
</div>
</blockquote>
</div>
<div>
<p class="MsoNormal">Awesome!<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><br>
<br>
<o:p></o:p></p>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><span
style="font-size:9.5pt">I'm
not sure how closely
everyone is reading the
intro emails, so we may
get more help if we also
send a slightly more
targeted "Hey, CFLAA isn't
obviously broken anymore.
Please help us find any
other problems/please
report performance numbers
to us," email. Whether we
do that this very second,
or when GSoC actually
starts, is up to you.</span><o:p></o:p></p>
</div>
</div>
</blockquote>
</div>
<div>
<p class="MsoNormal">Once this lands
in tree, I'll do a run on our
codebase to see if I see anything
obvious. I suspect others can do
the same.<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><br>
<br>
Philip<o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><br>
<br>
<o:p></o:p></p>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">On Wed,
May 11, 2016 at 3:02 PM,
Jia Chen via llvm-dev <<a
moz-do-not-send="true"
href="mailto:llvm-dev@lists.llvm.org"
target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a></a>>
wrote:<o:p></o:p></p>
<blockquote
style="border:none;border-left:solid
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0in 0in
6.0pt;margin-left:4.8pt;margin-right:0in">
<div>
<p class="MsoNormal">Dear
LLVM community,<br>
<br>
I am a GSoC student
this year working on
the project of
improving alias
analysis in LLVM.<br>
<br>
The proposal initially
came from a discussion
I had with various
devs on the mailing
list some time ago
[1]. The general goal
of this project is to
make alias analysis
(in particular,
cfl-aa) "better", and
to be more concrete
here is a list of
objectives I had in
mind:<br>
<br>
- Evaluating the
current state of
cfl-aa, and fix all
known bugs. <br>
- Improving the
precision of cfl-aa.
Although flow
sensitivity may not be
very helpful for LLVM
in its current form,
field sensitivity
should be something
important and I'll
definitely try to add
it to cfl-aa. Given
the complexity LLVM's
memory model has, my
guess is that I may
need to spend most of
my summer on this
task.<br>
- Improving the
performance of cfl-aa.
(It is fairly
efficient in its
current form, IMO.
Further performance
tuning may be needed
if more features such
as field sensitivity
were added.)<br>
- Understanding how
various clients
interacts with cfl-aa,
and exploring various
ways to minimize
precision/performance
losses caused by the
interaction.<br>
- If time permits,
maybe I can look at
scev-aa and try to
bring it back to the
compilation pipeline.<br>
<br>
I know these
objectives are not as
clear cut as other
GSoC projects people
used to have, and it
is hard to come up
with a clear schedule
as well as a success
metric. Nevertheless
even if my
contributions may seem
fragmented and
incremental, I felt
that as long as the
work is useful to the
community, it is going
to be the most
valuable summer I've
ever had as a student.<br>
<br>
** Current Status **<br>
<br>
I've submitted a
simple patch last week
(D19776) to fix a
subtle bug in cfl-aa.
After applying the
patch on r267335 and
bootstrap LLVM/clang
with cfl-aa enabled on
its own as well as
behind basic-aa on an
x86 machine, I ran
test-suite with lit
and saw no failed test
cases. I didn't time
the tests in any
rigorous way, but it
didn't look like
cfl-aa add very
noticable performance
overhead. It may be a
good time, I think, to
call for people's help
to test cfl-aa on
their internal
codebase. If
everything goes well,
we should be able to
safely turn on cfl-aa
by default soon.<br>
<br>
Let me conclude this
introduction by saying
thank you for
accepting my proposal,
and in particular I
want to thank my
mentors George and Hal
for the providing me
with so much support
and guidance. Please
let me know if you
have any comments or
suggestions.<br>
<br>
[1] <a
moz-do-not-send="true"
href="http://lists.llvm.org/pipermail/llvm-dev/2016-March/096851.html"
target="_blank">
<a class="moz-txt-link-freetext" href="http://lists.llvm.org/pipermail/llvm-dev/2016-March/096851.html">http://lists.llvm.org/pipermail/llvm-dev/2016-March/096851.html</a></a><span
style="color:#888888"><br>
<br>
<o:p></o:p></span></p>
<pre><span style="color:#888888">-- <o:p></o:p></span></pre>
<pre><span style="color:#888888">Best Regards,<o:p></o:p></span></pre>
<pre><span style="color:#888888"><o:p> </o:p></span></pre>
<pre><span style="color:#888888">--<o:p></o:p></span></pre>
<pre><span style="color:#888888">Jia Chen<o:p></o:p></span></pre>
<pre><span style="color:#888888">Department of Computer Science<o:p></o:p></span></pre>
<pre><span style="color:#888888">University of Texas at Austin<o:p></o:p></span></pre>
<pre><span style="color:#888888"><a moz-do-not-send="true" href="mailto:jchen@cs.utexas.edu" target="_blank">jchen@cs.utexas.edu</a><o:p></o:p></span></pre>
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<pre class="moz-signature" cols="72">--
Best Regards,
--
Jia Chen
Department of Computer Science
University of Texas at Austin
<a class="moz-txt-link-abbreviated" href="mailto:jchen@cs.utexas.edu">jchen@cs.utexas.edu</a></pre>
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