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| <div class="doc_title"> |
| Open LLVM Projects |
| </div> |
| |
| <ul> |
| <li><a href="#what">What is this?</a></li> |
| <li><a href="#improving">Improving the current system</a> |
| <ol> |
| <li><a href="#glibc">Port glibc to LLVM</a></li> |
| <li><a href="#NightlyTest">Improving the Nightly Tester</a></li> |
| <li><a href="#programs">Compile programs with the LLVM Compiler</a></li> |
| <li><a href="#llvm_ir">Extend the LLVM intermediate representation</a></li> |
| <li><a href="#misc_imp">Miscellaneous Improvements</a></li> |
| </ol></li> |
| |
| <li><a href="#new">Adding new capabilities to LLVM</a> |
| <ol> |
| <li><a href="#pointeranalysis">Pointer and Alias Analysis</a></li> |
| <li><a href="#profileguided">Profile Guided Optimization</a></li> |
| <li><a href="#xforms">New Transformations and Analyses</a></li> |
| <li><a href="#x86be">X86 Back-end Improvements</a></li> |
| <li><a href="#misc_new">Miscellaneous Additions</a></li> |
| </ol></li> |
| </ul> |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="what">What is this?</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>This document is meant to be a sort of "big TODO list" for LLVM. Each |
| project in this document is something that would be useful for LLVM to have, and |
| would also be a great way to get familiar with the system. Some of these |
| projects are small and self-contained, which may be implemented in a couple of |
| days, others are larger. Several of these projects may lead to interesting |
| research projects in their own right. In any case, we welcome all |
| contributions.</p> |
| |
| <p>If you are thinking about tackling one of these projects, please send a mail |
| to the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM |
| Developer's</a> mailing list, so that we know the project is being worked on. |
| Additionally this is a good way to get more information about a specific project |
| or to suggest other projects to add to this page. Another good place to look |
| for ideas is the <a href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug |
| tracker</a>.</p> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="improving">Improving the current system</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>Improvements to the current infrastructure are always very welcome and tend |
| to be fairly straight-forward to implement. Here are some of the key areas that |
| can use improvement...</p> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="glibc">Port glibc to LLVM</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>It would be very useful to <a |
| href="http://www.gnu.org/software/libc/porting.html">port</a> <a |
| href="http://www.gnu.org/software/glibc/">glibc</a> to LLVM. This would allow a |
| variety of interprocedural algorithms to be much more effective in the face of |
| library calls. The most important pieces to port are things like the string |
| library and the <tt>stdio</tt> related functions... low-level system calls like |
| '<tt>read</tt>' should stay unimplemented in LLVM.</p> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="NightlyTest">Improving the Nightly Tester</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>The <a href="/testresults/">Nightly Tester</a> is a simple perl script |
| (located in <tt>utils/NightlyTest.pl</tt>) which runs every night to generate a |
| daily report. It could use the following improvements:</p> |
| |
| <ol> |
| <li>Regression tests - We should run the regression tests in addition to the |
| program tests...</li> |
| </ol> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="programs">Compile programs with the LLVM Compiler</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>We are always looking for new testcases and benchmarks for use with LLVM. In |
| particular, it is useful to try compiling your favorite C source code with LLVM. |
| If it doesn't compile, try to figure out why or report it to the <a |
| href="http://mail.cs.uiuc.edu/pipermail/llvmbugs/">llvm-bugs</a> list. If you |
| get the program to compile, it would be extremely useful to convert the build |
| system to be compatible with the LLVM Programs testsuite so that we can check it |
| into CVS and the automated tester can use it to track progress of the |
| compiler.</p> |
| |
| <p>When testing a code, try running it with a variety of optimizations, and with |
| all the back-ends: CBE, llc, and lli.</p> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="llvm_ir">Extend the LLVM intermediate representation</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ol> |
| |
| <li>Add a new conditional move instruction: <tt>X = select bool Cond, Y, |
| Z</tt></li> |
| |
| <li>Add support for platform-independent prefetch support. The GCC <a |
| href="http://gcc.gnu.org/projects/prefetch.html">prefetch project</a> page |
| has a good survey of the prefetching capabilities of a variety of modern |
| processors.</li> |
| |
| </ol> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="misc_imp">Miscellaneous Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ol> |
| <li>Someone needs to look into getting the <tt>ranlib</tt> tool to index LLVM |
| bytecode files, so that linking in .a files is not hideously slow. They |
| would also then have to implement the reader for this index in |
| <tt>gccld</tt>.</li> |
| |
| <li>Rework the PassManager to be more flexible</li> |
| |
| <li>Some transformations and analyses only work on reducible flow graphs. It |
| would be nice to have a transformation which could be "required" by these passes |
| which makes irreducible graphs reducible. This can easily be accomplished |
| through code duplication. See <a |
| href="http://citeseer.nj.nec.com/janssen97making.html">Making Graphs Reducible |
| with Controlled Node Splitting</a> and perhaps <a |
| href="http://doi.acm.org/10.1145/262004.262005">Nesting of Reducible and |
| Irreducible Loops</a>.</li> |
| |
| </ol> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| <div class="doc_section"> |
| <a name="new">Adding new capabilities to LLVM</a> |
| </div> |
| <!-- *********************************************************************** --> |
| |
| <div class="doc_text"> |
| |
| <p>Sometimes creating new things is more fun that improving existing things. |
| These projects tend to be more involved and perhaps require more work, but can |
| also be very rewarding.</p> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="pointeranalysis">Pointer and Alias Analysis</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>We have a <a href="AliasAnalysis.html">strong base for development</a> of |
| both pointer analysis based optimizations as well as pointer analyses |
| themselves. It seems natural to want to take advantage of this...</p> |
| |
| <ol> |
| <li>Implement a flow-sensitive context-sensitive alias analysis algorithm<br> |
| - Pick one of the somewhat efficient algorithms, but strive for maximum |
| precision</li> |
| |
| <li>Implement a flow-sensitive context-insensitive alias analysis algorithm<br> |
| - Just an efficient local algorithm perhaps?</li> |
| |
| <li>Implement an interface to update analyses in response to common code motion |
| transformations</li> |
| |
| <li>Implement alias-analysis-based optimizations: |
| <ul> |
| <li>Dead store elimination</li> |
| <li>...</li> |
| </ul></li> |
| </ol> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="profileguided">Profile Guided Optimization</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <p>We are getting to the point where we really need a unified infrastructure for |
| profile guided optimizations. It would be wonderful to be able to write profile |
| guided transformations which can be performed either at static compile time |
| (compile time or offline optimization time) or at runtime in a JIT type setup. |
| The LLVM transformation itself shouldn't need to know how it is being used.</p> |
| |
| <p>Ideas for profile guided transformations:</p> |
| |
| <ol> |
| <li>Superblock formation (with many optimizations)</li> |
| <li>Loop unrolling/peeling</li> |
| <li>Profile directed inlining</li> |
| <li>Code layout</li> |
| <li>...</li> |
| </ol> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="xforms">New Transformations and Analyses</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ol> |
| <li>Implement a Dependence Analysis Infrastructure<br> |
| - Design some way to represent and query dep analysis</li> |
| <li>Implement a strength reduction pass</li> |
| <li>Value range propagation pass</li> |
| <li>Implement an unswitching pass</li> |
| <li>Write a loop unroller, with a simple heuristic for when to unroll</li> |
| </ol> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_section"> |
| <a name="x86be">X86 Back-end Improvements</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ol> |
| <li>Implement a global register allocator</li> |
| <li>Implement a better instruction selector</li> |
| <li>Implement support for the "switch" instruction without requiring the |
| lower-switches pass.</li> |
| </ol> |
| |
| </div> |
| |
| <!-- ======================================================================= --> |
| <div class="doc_subsection"> |
| <a name="misc_new">Miscellaneous Additions</a> |
| </div> |
| |
| <div class="doc_text"> |
| |
| <ol> |
| <li>Write a new frontend for some language (Java? OCaml? Forth?)</li> |
| <li>Write a new backend for a target (IA64? MIPS? MMIX?)</li> |
| </ol> |
| |
| </div> |
| |
| <!-- *********************************************************************** --> |
| |
| <hr> |
| <div class="doc_footer"> |
| <address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address> |
| <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a> |
| <br> |
| Last modified: $Date$ |
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