384 lines
9.7 KiB
HTML
384 lines
9.7 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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<!-- Material used from: HTML 4.01 specs: http://www.w3.org/TR/html401/ -->
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<html>
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<head> <META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>Polly - Todo</title>
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<link type="text/css" rel="stylesheet" href="menu.css">
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<link type="text/css" rel="stylesheet" href="content.css">
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</head>
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<body>
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<!--#include virtual="menu.html.incl"-->
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<div id="content">
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<h3> Setup infrastructure at LLVM </h3>
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<p>We are currently moving to the LLVM infrastructure
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</p>
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<table class="wikitable" cellpadding="2">
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<tbody><tr>
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<th>Task
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</th><th> Status
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</th><th>Owner
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</th></tr>
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<tr>
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<th align="left"> Move to LLVM SVN
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</th><td class="done" align="center"> done</br>
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<a
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href="http://llvm.org/svn/llvm-project/polly"
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>http://llvm.org/svn/llvm-project/polly</a>
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</td><td> Tobias
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</td></tr>
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<tr>
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<th align="left"> Git mirror
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</th><td class="done" align="center"> done<br />
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git://llvm.org/git/polly.git
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</td><td> Tobias
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</td></tr>
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<tr>
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<th align="left"> Commit mails
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</th><td class="done" align="center"> done <br />
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llvm-commits@cs.uiuc.edu
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</td><td> Tobias
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</td></tr>
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<tr>
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<th align="left"> LLVM Bugzilla category
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</th><td class="done" align="center"> done <br />
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<a href="http://llvm.org/bugs/enter_bug.cgi?product=Projects">LLVM Bugzilla</a>
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<br />
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(Product is 'Projects', Component is 'Polly')
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</td><td> Tobias
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<tr>
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<th align="left"> Website
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</th><td class="inprogress" align="center"> in progress
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<br />
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<a href="http://polly.grosser.es">http://polly.grosser.es</a>,
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later maybe polly.llvm.org
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</td><td> Tobias
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</td></tr>
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<tr>
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<th align="left">Buildbot that runs 'make polly-test'
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</th><td class="done" align="center">
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done<br />
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<a
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href="http://google1.osuosl.org:8011/console">http://google1.osuosl.org:8011/console</a>
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<td> Tobias,<br />Raghesh,<br /> Andreas
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</td></tr>
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<tr>
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<th align="left"> Nightly performance/coverage tests<br /> (with the llvm
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test-suite)
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</th><td align="center">
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</th><td> Andreas
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</td></tr>
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</th><td>
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</td></tr>
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</tbody></table>
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<h3> Phase 2 </h3>
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<p>The second phase of Polly can build on a robust, but very limited framework.
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In this phase work on removing limitations and extending the framework is
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planned. Also we plan the first very simple transformations. Furthermore the
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build system will be improved to simplify deployment.
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</p>
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<table class="wikitable" cellpadding="2">
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<tbody><tr>
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<th colspan="3" style="background: none repeat scroll 0% 0% rgb(239, 239,
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239);"> Frontend
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</th></tr>
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<tr>
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<th width="400px"> Task
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</th><th width="150px"> Status
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</th><th>Owner
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</th></tr>
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<tr>
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<th align="left"> Support for casts in expressions
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</th><td>
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</td><td>
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</td><td>
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</td></tr>
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<tr>
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<th align="left"> Support multi dimensional arrays.
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</th><td align="center"> planning
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</td><td> Tobias
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</td></tr>
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<tr>
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<th align="left"> Alias sets
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</th></tr>
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<tr>
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<th colspan="4" style="background: none repeat scroll 0% 0% rgb(239, 239,
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239);"> Middle end
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</th></tr>
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<tr>
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<th width="400px"> Task
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</th><th width="80px"> Status
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</th><th>Owner
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</th></tr>
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<tr>
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<th align="left"> Implement ISL dependency analysis pass
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</th><td class="done" align="center"> working
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</td><td> Tobias
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</td></tr>
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<tr>
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<th align="left"> Connect pocc/pluto
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</th><td class="done" align="center"> working
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</td><td> Tobias
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</td></tr>
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<tr>
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<th align="left"> Finish OpenSCoP support
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</th><td class="open">Blocked (waiting for OpenSCoP)
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</td><td>
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</td><td>
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</td></tr>
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<tr>
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<th align="left"> Add SCoPLib 0.2 support to connect pocc
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</th><td class="done" align="center">done
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</td><td> Tobias
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</td></tr>
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<tr>
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<th align="left"> Write simple loop blocking
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</th><td>
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</td><td>
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</td><td>
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</td></tr>
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<tr>
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<th colspan="4" style="background: none repeat scroll 0% 0% rgb(239, 239,
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239);"> Backend
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</th></tr>
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<tr>
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<th width="400px"> Task
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</th><th width="80px"> Status
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</th><th>Owner
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</th></tr>
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<tr>
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<th align="left"> Code generation for non 64bit targets
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</th><td>
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</td><td>
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</td><td>
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</td></tr>
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<tr>
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<th align="left"> Add write support for data access functions
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</th><td class="open">Still open
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</td><td>
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</td><td>
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</td></tr>
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<tr>
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<th align="left"> Create vector loops
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</th><td class="inprogress">70% done
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</td><td>Tobias
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</td></tr>
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<tr>
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<th align="left">Create OpenMP
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loops
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</th><td class="inprogress">90% done
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</td><td> Raghesh & Tobias
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</td></tr>
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<tr>
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<th colspan="4" style="background: none repeat scroll 0% 0% rgb(239, 239,
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239);"> General tasks
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</th></tr>
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<tr>
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<th width="300px"> Task
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</th><th width="80px"> Status
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</th><th>Owner
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</th></tr>
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<tr>
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<th align="left"> Commit RegionPass patch upstream
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</th><td class="done" align="center"> done
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</td><td> Tobias
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</td></tr>
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<tr>
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<th align="left"> Build against an installed LLVM
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</th><td class="inprogress"> Partial (cmake build without tests)
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</td><td> ether
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</td></tr>
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<tr>
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<th align="left"> Setup buildbot regression testers using LNT
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</th><td class="open">Still open
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</td><td>
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</td><td>
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</td></tr>
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</tbody></table>
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<h3>Phase 1 - Get something
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working (Finished October 2010)</span></h3>
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<p>The first iteration of this project aims to create a minimal working version
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of this framework, that is capable to transform an LLVM-IR program to the
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polyhedral model
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and back to LLVM-IR without applying any transformations.
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</p>
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<table class="wikitable" cellpadding="2">
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<tbody><tr>
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<th colspan="4" style="background: none repeat scroll 0% 0% rgb(239, 239,
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239);"> Frontend
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</th></tr>
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<tr>
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<th width="300px"> Task
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</th><th width="150px"> Status
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</th><th>Owner
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</th></tr>
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<tr>
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<th align="left"> Region detection
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</td><td class="done"> Working + Committed upstream
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</td><td>Ether
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</td></tr>
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<tr>
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<th align="left"> Access Functions
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</td><td class="done"> Working
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</td><td>John + Ether
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</td></tr>
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<tr>
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<th align="left"> Alias sets
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</td><td class="open"> Still open
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</td></tr>
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<tr>
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<th align="left"> Scalar evolution to affine expression
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</td><td class="done"> Done
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</td><td>
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Ether
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</td></tr>
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<tr>
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<th align="left"> SCoP extraction
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</td><td class="done"> Working
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</td><td>Tobias + Ether
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</td></tr>
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<tr>
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<th align="left"> SCoPs to polyhedral model
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</td><td class="done"> Working
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</td><td>Tobias + Ether
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</td></tr>
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<tr>
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<th colspan="4" style="background: none repeat scroll 0% 0% rgb(239, 239,
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239);"> Middle end
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</th></tr>
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<tr>
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<th width="300px"> Task
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</th><th width="80px"> Status
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</th><th>Owner
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</th></tr>
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<tr>
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<th align="left"> Define polyhedral description
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</td><td class="done"> Working
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</td><td>Tobias
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</td></tr>
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<tr>
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<th align="left"> Import/Export using current openscop version
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</td><td class="done"> Working
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</td><td>Tobias
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</td></tr>
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<tr>
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<th colspan="4" style="background: none repeat scroll 0% 0% rgb(239, 239,
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239);"> Backend
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</th></tr>
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<tr>
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<th width="300px"> Task
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</th><th width="80px"> Status
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</th><th>Owner
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</th></tr>
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<tr>
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<th align="left"> Create LLVM-IR using CLooG
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</td><td class="done"> Working
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</td><td> Tobias
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</td></tr>
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<tr>
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<th colspan="4" style="background: none repeat scroll 0% 0% rgb(239, 239,
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239);"> General tasks
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</th></tr>
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<tr>
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<th width="300px"> Task
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</th><th width="80px"> Status
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</th><th>Owner
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</th></tr>
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<tr>
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<th align="left"> Setup git repositories
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</td><td class="done"> Done
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</td><td> Tobias
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</td></tr>
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<tr>
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<th align="left"> Add CLooG/isl to build system
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</td><td class="done"> Works on Unix
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</td><td> Tobias
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</td></tr></tbody></table>
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<h3>Further projects </h3>
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<p>There are several great projects related to polly that can already be started
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or are possible in the near future. </p>
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<h4>Extend the post dominance analysis for infinite loops (small)</h4>
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<p>At the moment the post dominance analysis cannot handle infinite loops. All
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basic blocks in the CFG that do not return are - at the moment - not part of the
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post dominance tree.
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However by adding some virtual edges, they could be added to the post dominator
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tree. Where to add the edges needs some research.
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</p><p>This is a small project, that is is well defined. As it is directly in
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LLVM it can be easily committed upstream. It is useful for polly, as the
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RegionInfo pass will be able to detect regions in parts of the CFG that never
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return.
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</p><p><i>A good starter to get into LLVM</i>
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</p>
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<h4>Vectorization </h4>
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<p>It is planned to use Polly to support vectorization in LLVM.
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</p><p>The basic idea is to use Polly and the polyhedral tools to transform code
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such that the innermost loops can be executed in parallel. Afterwards during
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code generation in LLVM the loops will be created using vector instructions.
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</p><p>To start we plan to use <a href="http://pluto-compiler.sf.net"
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class="external text" title="http://pluto-compiler.sf.net"
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rel="nofollow">Pluto</a> to transform the loop nests. Pluto can generate vector
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parallel code and annotate the vector parallel loops. Some impressive results
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were shown on code that was afterwards vectorized by the icc enforcing
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vectorization. We believe LLVM can do even better, as it can interact directly
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with the polyhedral information.
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</p><p>As an example simple matrix multiplication:
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</p>
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<pre>
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for(i=0; i<M; i++)
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for(j=0; j<N; j++)
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for(k=0; k<K; k++)
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C[i][j] = beta*C[i][j] + alpha*A[i][k] * B[k][j];
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</pre>
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<p>After plutos transformations with added tiling and
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vectorization hints:
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</p>
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<pre>
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if ((K >= 1) && (M >= 1) && (N >= 1))
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for (t1=0;t1<=floord(M-1,32);t1++)
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for (t2=0;t2<=floord(N-1,32);t2++)
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for (t3=0;t3<=floord(K-1,32);t3++)
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for (t4=32*t1;t4<=min(M-1,32*t1+31);t4++)
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for (t5=32*t3;t5<=min(K-1,32*t3+31);t5++) {
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lbv=32*t2;
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ubv=min(N-1,32*t2+31);
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#pragma ivdep
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#pragma vector always
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for (t6=lbv; t6<=ubv; t6++)
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C[t4][t6]=beta*C[t4][t6]+alpha*A[t4][t5]*B[t5][t6];;
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}
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</pre>
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<p>In this example the innermost loop is parallel without any dependencies. </p>
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</div>
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</body>
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</html>
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