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-<center><h1><font size=7>Open LLVM Projects</font></h1></center>
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+ <link rel="stylesheet" href="llvm.css" type="text/css">
+</head>
+<body>
+
+<div class="doc_title">
+ Open LLVM Projects
+</div>
<ul>
- <li><a href="#what">What is this?</a>
+ <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><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="#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="#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><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>
+ <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="#x86be">X86 Back-end Improvements</a></li>
+ <li><a href="#misc_new">Miscellaneous Additions</a></li>
+ </ol></li>
</ul>
-<br><br>
+<div class="doc_author">
+ <p>Written by the <a href="http://llvm.cs.uiuc.edu/">LLVM Team</a></p>
+</div>
+
<!-- *********************************************************************** -->
-<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>
+<div class="doc_section">
+ <a name="what">What is this?</a>
+</div>
<!-- *********************************************************************** -->
-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>
+<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>
-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
+<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>
+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>
<!-- *********************************************************************** -->
-</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>
+<div class="doc_section">
+ <a name="improving">Improving the current system</a>
+</div>
<!-- *********************************************************************** -->
-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 class="doc_text">
-<!-- ======================================================================= -->
-</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>
+<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>
<!-- ======================================================================= -->
-</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>
+<div class="doc_subsection">
+ <a name="code-cleanups">Implementing Code Cleanup bugs</a>
+</div>
-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>
+<div class="doc_text">
-<ol>
-<li>Olden timings - Time the compilation and execution times for the Olden
- benchmark suite, keeping track of these values over time.
+<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="doc_subsection">
+ <a name="glibc">Port glibc to LLVM</a>
+</div>
-<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 neccesary to add the script-fu to gnuplotize it.
+<div class="doc_text">
-<li>Regression tests - We should run the regression tests in addition to the
- program tests...
-</ol><p>
+<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>
<!-- ======================================================================= -->
-</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>
+<div class="doc_subsection">
+ <a name="programs">Compile programs with the LLVM Compiler</a>
+</div>
-We are always looking for new testcases and benchmarks for use with LLVM. In
+<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>
+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>
+<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>
<!-- ======================================================================= -->
-</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>
+<div class="doc_subsection">
+ <a name="llvm_ir">Extend the LLVM intermediate representation</a>
+</div>
+
+<div class="doc_text">
<ol>
-<li>Transform <tt>setjmp</tt> and <tt>longjmp</tt> calls to use the LLVM
- <tt>invoke</tt> mechanism.
-<li>Add support for a volatile attribute on loads and stores
-<li>Support for variable argument functions
-<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
+<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.
+ processors.</li>
+
</ol>
+</div>
<!-- ======================================================================= -->
-</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>
+<div class="doc_subsection">
+ <a name="misc_imp">Miscellaneous Improvements</a>
+</div>
+
+<div class="doc_text">
<ol>
-<li>Improve the efficiency of the bytecode loader/writer, allow streaming lazy
- loading of functions from the bytecode (for use by the JIT, for example)<br>
-<li>Rework the PassManager
-<li>Do not encode zero intializers for large arrays into the bytecode
+<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
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>.
+Irreducible Loops</a>.</li>
+
</ol>
+</div>
<!-- *********************************************************************** -->
-</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>
+<div class="doc_section">
+ <a name="new">Adding new capabilities to LLVM</a>
+</div>
<!-- *********************************************************************** -->
-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 class="doc_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>
+
<!-- ======================================================================= -->
-</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>
+<div class="doc_subsection">
+ <a name="newfeaturebugs">Implementing new feature PRs</a>
+</div>
-We have a strong base for development of both pointer analysis based
-optimizations as well as pointer analyses themselves. It seems natural to want
-to take advantage of this...<p>
+<div class="doc_text">
+
+<p>Many ideas for feature requests are stored in LLVM bugzilla. Just <a href="http://llvm.org/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="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>Implement a flow-sensitive context-insensitive alias anlaysis algorithm<br>
- - Just an efficient local algorithm perhaps?
+ precision</li>
-<li>Implement an interface to update analyses in response to common code motion
- transformations
-<li>Implement alias analysis based optimizations:
+<li>Implement a flow-sensitive context-insensitive alias analysis algorithm<br>
+ - Just an efficient local algorithm perhaps?</li>
+
+<li>Implement alias-analysis-based optimizations:
<ul>
- <li>Dead store elimination
- <li>Store+Reload or "store forwarding" elimination:<p>
- Change:
- <pre>
- store int X, int* P
- Y = load int* P</pre>
- into:
- <pre>
- store int X, int *P
- Y = X</pre>
- </ul>
+ <li>Dead store elimination</li>
+ <li>...</li>
+ </ul></li>
</ol>
+</div>
+
<!-- ======================================================================= -->
-</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>
+<div class="doc_subsection">
+ <a name="profileguided">Profile Guided Optimization</a>
+</div>
+
+<div class="doc_text">
-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>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>
-Ideas for profile guided transformations:<p>
+<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>
+<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>
<!-- ======================================================================= -->
-</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>
+<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>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 a tail recursion elimination pass
-<li>Implement an unswitching pass
+ - 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>
+
<!-- ======================================================================= -->
-</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>
+<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>Implement a better instruction selector
-<li>Implement a static compiler in addition to the JIT (easy project)
+<li>Implement a better instruction selector</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>
</ol>
+</div>
+
<!-- ======================================================================= -->
-</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>
+<div class="doc_section">
+ <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>Write a new backend for a target (IA64? MIPS? MMIX?)
+<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 new backend for a target (IA64? MIPS? MMIX?)</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>
<!-- *********************************************************************** -->
-</ul>
-<!-- *********************************************************************** -->
-<hr><font size-1>
-<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
-<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
-<!-- hhmts start -->
-Last modified: Wed Feb 26 10:37:31 CST 2003
-<!-- hhmts end -->
-</font></body></html>
+<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
+ src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
+
+ <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
+ <a href="http://llvm.cs.uiuc.edu">LLVM Compiler Infrastructure</a><br>
+ Last modified: $Date$
+</address>
+
+</body>
+</html>