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| <html><head><title>Open LLVM Projects</title></head> |
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| <center><h1><font size=7>Open LLVM Projects</font></h1></center> |
| |
| <ul> |
| <li><a href="#what">What is this?</a> |
| <li><a href="#improving">Improving the current system</a> |
| <ol> |
| <li><a href="#glibc">Port glibc to LLVM</a> |
| <li><a href="#NightlyTest">Improving the Nightly Tester</a> |
| <li><a href="#programs">Compile programs with the LLVM Compiler</a> |
| <li><a href="#llvm_ir">Extend the LLVM intermediate representation</a> |
| <li><a href="#misc_imp">Miscellaneous Improvements</a> |
| </ol> |
| |
| <li><a href="#new">Adding new capabilities to LLVM</a> |
| <ol> |
| <li><a href="#pointeranalysis">Pointer and Alias Analysis</a> |
| <li><a href="#profileguided">Profile Guided Optimization</a> |
| <li><a href="#xforms">New Transformations and Analyses</a> |
| <li><a href="#x86be">X86 Back-end Improvements</a> |
| <li><a href="#misc_new">Miscellaneous Additions</a> |
| </ol> |
| </ul> |
| |
| <br><br> |
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| <table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0> |
| <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b> |
| <a name="what">What is this? |
| </b></font></td></tr></table><ul> |
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| |
| 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> |
| |
| 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.<p> |
| |
| |
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| </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0> |
| <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b> |
| <a name="improving">Improving the current system |
| </b></font></td></tr></table><ul> |
| <!-- *********************************************************************** --> |
| |
| 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> |
| |
| <!-- ======================================================================= --> |
| </ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> |
| <tr><td> </td><td width=100%> |
| <font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b> |
| <a name="glibc">Port glibc to LLVM |
| </b></font></td></tr></table><ul> |
| |
| 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> |
| |
| |
| <!-- ======================================================================= --> |
| </ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> |
| <tr><td> </td><td width=100%> |
| <font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b> |
| <a name="NightlyTest">Improving the Nightly Tester |
| </b></font></td></tr></table><ul> |
| |
| The <a href="/testresults/">Nightly Tester</a> is a simple perl script (located |
| in utils/NightlyTest.pl) which runs every night to generate a daily report. It |
| could use the following improvements:<p> |
| |
| <ol> |
| <li>Olden timings - Time the compilation and execution times for the Olden |
| benchmark suite, keeping track of these values over time. |
| |
| <li>Graphs - It would be great to have gnuplot graphs to keep track of how the |
| tree is changing over time. We already gather a several statistics, it |
| just necessary to add the script-fu to gnuplotize it. |
| |
| <li>Regression tests - We should run the regression tests in addition to the |
| program tests... |
| </ol><p> |
| |
| |
| <!-- ======================================================================= --> |
| </ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> |
| <tr><td> </td><td width=100%> |
| <font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b> |
| <a name="programs">Compile programs with the LLVM Compiler |
| </b></font></td></tr></table><ul> |
| |
| 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> |
| |
| When testing a code, try running it with a variety of optimizations, and with |
| all the back-ends: CBE, llc, and lli.<p> |
| |
| |
| <!-- ======================================================================= --> |
| </ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> |
| <tr><td> </td><td width=100%> |
| <font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b> |
| <a name="llvm_ir">Extend the LLVM intermediate representation |
| </b></font></td></tr></table><ul> |
| |
| <ol> |
| <li>Add a new conditional move instruction: <tt>X = select bool Cond, Y, Z</tt> |
| <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. |
| </ol> |
| |
| |
| <!-- ======================================================================= --> |
| </ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> |
| <tr><td> </td><td width=100%> |
| <font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b> |
| <a name="misc_imp">Miscellaneous Improvements |
| </b></font></td></tr></table><ul> |
| |
| <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>.<br> |
| |
| <li>Improve the efficiency of the bytecode loader/writer<br> |
| <li>Extend the FunctionPassManager to use a ModuleProvider to stream functions |
| in on demand. This would improve the efficiency of the JIT. |
| <li>Rework the PassManager to be more flexible |
| <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>. |
| </ol> |
| |
| |
| <!-- *********************************************************************** --> |
| </ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0> |
| <tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b> |
| <a name="new">Adding new capabilities to LLVM |
| </b></font></td></tr></table><ul> |
| <!-- *********************************************************************** --> |
| |
| 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> |
| |
| <!-- ======================================================================= --> |
| </ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> |
| <tr><td> </td><td width=100%> |
| <font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b> |
| <a name="pointeranalysis">Pointer and Alias Analysis |
| </b></font></td></tr></table><ul> |
| |
| 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>Implement a flow-sensitive context-insensitive alias analysis algorithm<br> |
| - Just an efficient local algorithm perhaps? |
| |
| <li>Implement an interface to update analyses in response to common code motion |
| transformations |
| <li>Implement alias analysis based optimizations: |
| <ul> |
| <li>Dead store elimination |
| </ul> |
| </ol> |
| |
| <!-- ======================================================================= --> |
| </ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> |
| <tr><td> </td><td width=100%> |
| <font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b> |
| <a name="profileguided">Profile Guided Optimization |
| </b></font></td></tr></table><ul> |
| |
| 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> |
| |
| Ideas for profile guided transformations:<p> |
| |
| <ol> |
| <li>Superblock formation (with many optimizations) |
| <li>Loop unrolling/peeling |
| <li>Profile directed inlining |
| <li>Code layout |
| <li>... |
| </ol><p> |
| |
| |
| <!-- ======================================================================= --> |
| </ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> |
| <tr><td> </td><td width=100%> |
| <font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b> |
| <a name="xforms">New Transformations and Analyses |
| </b></font></td></tr></table><ul> |
| |
| <ol> |
| <li>Implement a Dependence Analysis Infrastructure<br> |
| - Design some way to represent and query dep analysis |
| <li>Implement a faster Dominator Set Construction Algorithm<br> |
| - A linear time or nearly so algorithm |
| <li>Implement a strength reduction pass |
| <li>Value range propagation pass |
| <li>Implement an unswitching pass |
| <li>Write a loop unroller, with a simple heuristic for when to unroll |
| </ol> |
| |
| <!-- ======================================================================= --> |
| </ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> |
| <tr><td> </td><td width=100%> |
| <font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b> |
| <a name="x86be">X86 Back-end Improvements |
| </b></font></td></tr></table><ul> |
| |
| <ol> |
| <li>Implement a global register allocator |
| <li>Implement a better instruction selector |
| <li>Implement support for the "switch" instruction without requiring the |
| lower-switches pass. |
| </ol> |
| |
| <!-- ======================================================================= --> |
| </ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0> |
| <tr><td> </td><td width=100%> |
| <font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b> |
| <a name="misc_new">Miscellaneous Additions |
| </b></font></td></tr></table><ul> |
| |
| <ol> |
| <li>Write a new frontend for some language (Java? OCaml? Forth?) |
| <li>Write a new backend for a target (IA64? MIPS? MMIX?) |
| </ol> |
| |
| |
| <!-- *********************************************************************** --> |
| </ul> |
| <!-- *********************************************************************** --> |
| |
| <hr><font size-1> |
| <address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address> |
| <a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a> |
| <br> |
| <!-- Created: Tue Aug 6 15:00:33 CDT 2002 --> |
| <!-- hhmts start --> |
| Last modified: Wed Oct 1 16:48:54 CDT 2003 |
| <!-- hhmts end --> |
| </font></body></html> |
