<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="#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="#target">Target backend improvements</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="#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_author">
+ <p>Written by the <a href="http://llvm.cs.uiuc.edu/">LLVM Team</a></p>
+</div>
+
+
<!-- *********************************************************************** -->
<div class="doc_section">
<a name="what">What is this?</a>
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>
+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="doc_subsection">
- <a name="glibc">Port glibc to LLVM</a>
+ <a name="code-cleanups">Implementing Code Cleanup bugs</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>
+<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="NightlyTest">Improving the Nightly Tester</a>
+ <a name="glibc">Port glibc to LLVM</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>
+<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="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
</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection">
+ <a name="target">Target backend improvements</a>
+</div>
+
+<div class="doc_text">
+
+<ol>
+ <li>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.</li>
+</ol>
+
+</div>
+
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="misc_imp">Miscellaneous Improvements</a>
<div class="doc_text">
-<p>Sometimes creating new things is more fun that improving existing things.
+<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="doc_subsection">
+ <a name="newfeaturebugs">Implementing new feature PRs</a>
+</div>
+
+<div class="doc_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="doc_subsection">
<a name="pointeranalysis">Pointer and Alias Analysis</a>
<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 class="doc_subsection">
- <a name="profileguided">Profile Guided Optimization</a>
+ <a name="profileguided">Profile-Guided Optimization</a>
</div>
<div class="doc_text">
transformations as well as improvements to the current profiling system.
</p>
-<p>Ideas for profile guided transformations:</p>
+<p>Ideas for profile-guided transformations:</p>
<ol>
<li>Superblock formation (with many optimizations)</li>
<div class="doc_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>
-<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_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>
+<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>
<!-- ======================================================================= -->
-<div class="doc_subsection">
+<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>
+<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>
+<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>
<!-- *********************************************************************** -->
<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>
+<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>
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+</address>
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