[llvm-commits] CVS: llvm-www/OpenProjects.html
Chris Lattner
lattner at cs.uiuc.edu
Fri Jan 7 10:55:44 PST 2005
Changes in directory llvm-www:
OpenProjects.html added (r1.1)
---
Log message:
New open projects doc, largely the same as docs/OpenProjects.html, but
cleaned up and converted to www_* instead of doc_*.
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Diffs of the changes: (+379 -0)
Index: llvm-www/OpenProjects.html
diff -c /dev/null llvm-www/OpenProjects.html:1.1
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+ <!--#include virtual="header.incl" -->
+
+ <div class="www_sectiontitle">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="#code-cleanups">Implementing Code Cleanup bugs</a></li>
+ <li><a href="#glibc">Port glibc to LLVM</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="#benchmark">Benchmark the LLVM compiler</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="#newfeaturebugs">Implementing new feature PRs</a></li>
+ <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="#codegen">Code Generator Improvements</a></li>
+ <li><a href="#misc_new">Miscellaneous Additions</a></li>
+ </ol></li>
+ </ul>
+
+ <div class="doc_author">
+ <p>Written by the <a href="http://llvm.cs.uiuc.edu/">LLVM Team</a></p>
+ </div>
+
+
+ <!-- *********************************************************************** -->
+ <div class="www_sectiontitle">
+ <a name="what">What is this?</a>
+ </div>
+ <!-- *********************************************************************** -->
+
+ <div class="www_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.
+ </p>
+
+ <p>The projects in this page are open-ended. More specific projects are
+ filed as unassigned enhancements in the <a href="http://llvm.cs.uiuc.edu/bugs/">
+ LLVM bug tracker</a>. See the <a href="http://llvm.cs.uiuc.edu/bugs/buglist.cgi?keywords_type=allwords&keywords=&bug_status=NEW&bug_status=ASSIGNED&bug_status=REOPENED&bug_severity=enhancement&emailassigned_to1=1&emailtype1=substring&email1=unassigned">list of currently outstanding issues</a> if you wish to help improve LLVM.</p>
+
+ </div>
+
+ <!-- *********************************************************************** -->
+ <div class="www_sectiontitle">
+ <a name="improving">Improving the current system</a>
+ </div>
+ <!-- *********************************************************************** -->
+
+ <div class="www_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="www_subsubsection">
+ <a name="code-cleanups">Implementing Code Cleanup bugs</a>
+ </div>
+
+ <div class="www_text">
+
+ <p>
+ The <a href="http://llvm.cs.uiuc.edu/bugs/">LLVM bug tracker</a> occasionally
+ has <a
+ href="http://llvm.cs.uiuc.edu/bugs/buglist.cgi?short_desc_type=allwordssubstr&short_desc=&long_desc_type=allwordssubstr&long_desc=&bug_file_loc_type=allwordssubstr&bug_file_loc=&status_whiteboard_type=allwordssubstr&status_whiteboard=&keywords_type=allwords&keywords=code-cleanup&bug_status=NEW&bug_status=ASSIGNED&bug_status=REOPENED&emailassigned_to1=1&emailtype1=substring&email1=&emailassigned_to2=1&emailreporter2=1&emailcc2=1&emailtype2=substring&email2=&bugidtype=include&bug_id=&votes=&changedin=&chfieldfrom=&chfieldto=Now&chfieldvalue=&cmdtype=doit&order=Bug+Number&field0-0-0=noop&type0-0-0=noop&value0-0-0=">"code-cleanup" bugs</a> filed in it. Taking one of these and fixing it is a good
+ way to get your feet wet in the LLVM code and discover how some of its components
+ work.
+ </p>
+
+ </div>
+
+ <!-- ======================================================================= -->
+ <div class="www_subsubsection">
+ <a name="glibc">Port glibc to LLVM</a>
+ </div>
+
+ <div class="www_text">
+
+ <p>It would be very useful to <a
+ href="http://www.gnu.org/software/libc/manual/html_node/Porting.html">port</a> <a
+ href="http://www.gnu.org/software/libc/">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="www_subsubsection">
+ <a name="programs">Compile programs with the LLVM Compiler</a>
+ </div>
+
+ <div class="www_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="www_subsubsection">
+ <a name="llvm_ir">Extend the LLVM intermediate representation</a>
+ </div>
+
+ <div class="www_text">
+
+ <ol>
+ <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="www_subsubsection">
+ <a name="benchmark">Benchmark the LLVM compiler</a>
+ </div>
+
+ <div class="www_text">
+
+ <p>Find benchmarks either using our <a
+ href="http://llvm.cs.uiuc.edu/testresults/">test results</a> or on your own,
+ where LLVM code generators do not produce optimal code or simply where another
+ compiler produces better code. Try to minimize the test case that demonstrates
+ the issue. Then, either <a href="http://llvm.cs.uiuc.edu/bugs/">submit a
+ bug</a> with your testcase and the code that LLVM produces vs. the code that it
+ <em>should</em> produce, or even better, see if you can improve the code
+ generator and submit a patch. The basic idea is that it's generally quite easy
+ for us to fix performance problems if we know about them, but we generally don't
+ have the resources to go finding out why performance is bad.</p>
+
+ </div>
+
+ <!-- ======================================================================= -->
+ <div class="www_subsubsection">
+ <a name="misc_imp">Miscellaneous Improvements</a>
+ </div>
+
+ <div class="www_text">
+
+ <ol>
+ <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="www_sectiontitle">
+ <a name="new">Adding new capabilities to LLVM</a>
+ </div>
+ <!-- *********************************************************************** -->
+
+ <div class="www_text">
+
+ <p>Sometimes creating new things is more fun than 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="www_subsubsection">
+ <a name="newfeaturebugs">Implementing new feature PRs</a>
+ </div>
+
+ <div class="www_text">
+
+ <p>Many ideas for feature requests are stored in LLVM bugzilla. Just <a
+ href="http://llvm.cs.uiuc.edu/bugs/buglist.cgi?short_desc_type=allwordssubstr&short_desc=&long_desc_type=allwordssubstr&long_desc=&bug_file_loc_type=allwordssubstr&bug_file_loc=&status_whiteboard_type=allwordssubstr&status_whiteboard=&keywords_type=allwords&keywords=new-feature&bug_status=UNCONFIRMED&bug_status=NEW&bug_status=ASSIGNED&bug_status=REOPENED&emailassigned_to1=1&emailtype1=substring&email1=&emailassigned_to2=1&emailreporter2=1&emailcc2=1&emailtype2=substring&email2=&bugidtype=include&bug_id=&votes=&changedin=&chfieldfrom=&chfieldto=Now&chfieldvalue=&cmdtype=doit&namedcmd=All+PRs&newqueryname=&order=Bug+Number&field0-0-0=noop&type0-0-0=noop&value0-0-0=">search for bugs with a "new-feature" keyword</a>.</p>
+
+ </div>
+
+ <!-- ======================================================================= -->
+ <div class="www_subsubsection">
+ <a name="pointeranalysis">Pointer and Alias Analysis</a>
+ </div>
+
+ <div class="www_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 new alias-analysis-based optimizations.</li>
+ </ol>
+
+ </div>
+
+ <!-- ======================================================================= -->
+ <div class="www_subsubsection">
+ <a name="profileguided">Profile-Guided Optimization</a>
+ </div>
+
+ <div class="www_text">
+
+ <p>We now have a unified infrastructure for writing profile-guided
+ transformations, which will work either at offline-compile-time or in the JIT,
+ but we don't have many transformations. We would welcome new profile-guided
+ transformations as well as improvements to the current profiling system.
+ </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>
+
+ <p>Improvements to the existing support:</p>
+
+ <ol>
+ <li>The current block and edge profiling code that gets inserted is very simple
+ and inefficient. Through the use of control-dependence information, many fewer
+ counters could be inserted into the code. Also, if the execution count of a
+ loop is known to be a compile-time or runtime constant, all of the counters in
+ the loop could be avoided.</li>
+
+ <li>You could implement one of the "static profiling" algorithms which analyze a
+ piece of code an make educated guesses about the relative execution frequencies
+ of various parts of the code.</li>
+
+ <li>You could add path profiling support, or adapt the existing LLVM path
+ profiling code to work with the generic profiling interfaces.</li>
+ </ol>
+
+ </div>
+
+ <!-- ======================================================================= -->
+ <div class="www_subsubsection">
+ <a name="xforms">New Transformations and Analyses</a>
+ </div>
+
+ <div class="www_text">
+
+ <ol>
+ <li>Implement <a href="http://www.cs.purdue.edu/homes/vandrutj/">GVN-PRE</a>, a
+ powerful and simple Partial Redundancy Elimination algorithm for SSA form</li>
+ <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>
+ </ol>
+
+ </div>
+
+ <!-- ======================================================================= -->
+ <div class="www_sectiontitle">
+ <a name="codegen">Code Generator Improvements</a>
+ </div>
+
+ <div class="www_text">
+
+ <ol>
+ <li>Improve the instruction selectors.</li>
+ <li>Implement support for the "switch" instruction without requiring the
+ lower-switches pass.</li>
+ <li>Implement interprocedural register allocation. The CallGraphSCCPass can be
+ used to implement a bottom-up analysis that will determine the *actual*
+ registers clobbered by a function. Use the pass to fine tune register usage
+ in callers based on *actual* registers used by the callee.</li>
+ <li>Write a new backend for a target (IA64? MIPS? MMIX?)</li>
+ <li>Improve the usefulness and utility of the Skeleton target backend:
+ <ul>
+ <li>Convert the non-functional Skeleton target to become an abstract machine
+ target (choose some simple instructions, a register set, etc). This will
+ become a much more useful example of a backend since it would be a simple
+ but <em>functional</em> backend. Examples of such architectures include MIX,
+ MMIX, <a
+ href="http://www.cs.cinvestav.mx/SC/prof_personal/adiaz/vhdl/DLX/">DLX</a>,
+ or come up with your own!</li>
+ <li>Use the new Skeleton backend in the Interpreter: compile LLVM to Skeleton
+ target, and then interpret that code instead of LLVM. Performance win would
+ be the primary goal, as the number of registers would be a small constant
+ instead of unbounded, for example.</li>
+ </ul></li>
+ </ol>
+
+ </div>
+
+ <!-- ======================================================================= -->
+ <div class="www_sectiontitle">
+ <a name="misc_new">Miscellaneous Additions</a>
+ </div>
+
+ <div class="www_text">
+
+ <ol>
+ <li>Port the <a href="http://www-sop.inria.fr/mimosa/fp/Bigloo/">Bigloo</A>
+ Scheme compiler, from Manuel Serrano at INRIA Sophia-Antipolis, to
+ output LLVM bytecode. It seems that it can already output .NET
+ bytecode, JVM bytecode, and C, so LLVM would ostensibly be another good
+ candidate.</li>
+ <li>Write a new frontend for C/C++ <b>in</b> C++, giving us the ability to
+ directly use LLVM C++ classes from within a compiler rather than use
+ C-based wrapper functions a la llvm-gcc. One possible starting point is the <a
+ href="http://www.parashift.com/c++-faq-lite/compiler-dependencies.html#faq-37.11">C++
+ yacc grammar by Ed Willink</a>.</li>
+ <li>Write a new frontend for some other language (Java? OCaml? Forth?)</li>
+ <li>Write a disassembler for machine code that would use TableGen to output
+ <tt>MachineInstr</tt>s for transformations, optimizations, etc.</li>
+ <li>Random test vector generator: Use a C grammar to generate random C code;
+ run it through llvm-gcc, then run a random set of passes on it using opt.
+ Try to crash opt. When opt crashes, use bugpoint to reduce the test case and
+ mail the result to yourself. Repeat ad infinitum.</li>
+ <li>Design a simple, recognizable logo.</li>
+ </ol>
+
+ </div>
+
+ <!-- *********************************************************************** -->
+
+ <hr>
+ <address>
+ <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
+ src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
+ <a href="http://validator.w3.org/check/referer"><img
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+
+ <a href="http://llvm.cs.uiuc.edu">LLVM Compiler Infrastructure</a><br>
+ Last modified: $Date: 2005/01/07 18:55:28 $
+ </address>
+
+ <!--#include virtual="footer.incl" -->
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