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3<html>
4<head>
5 <title>Open LLVM Projects</title>
6 <link rel="stylesheet" href="llvm.css" type="text/css">
7</head>
8<body>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]9
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]10<div class="doc_title">
11 Open LLVM Projects
12</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]13
14<ul>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]15 <li><a href="#what">What is this?</a></li>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]16 <li><a href="#improving">Improving the current system</a>
17 <ol>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]18 <li><a href="#glibc">Port glibc to LLVM</a></li>
19 <li><a href="#NightlyTest">Improving the Nightly Tester</a></li>
20 <li><a href="#programs">Compile programs with the LLVM Compiler</a></li>
21 <li><a href="#llvm_ir">Extend the LLVM intermediate representation</a></li>
22 <li><a href="#misc_imp">Miscellaneous Improvements</a></li>
23 </ol></li>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]24
25 <li><a href="#new">Adding new capabilities to LLVM</a>
26 <ol>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]27 <li><a href="#pointeranalysis">Pointer and Alias Analysis</a></li>
28 <li><a href="#profileguided">Profile Guided Optimization</a></li>
29 <li><a href="#xforms">New Transformations and Analyses</a></li>
30 <li><a href="#x86be">X86 Back-end Improvements</a></li>
31 <li><a href="#misc_new">Miscellaneous Additions</a></li>
32 </ol></li>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]33</ul>
34
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]35<!-- *********************************************************************** -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]36<div class="doc_section">
37 <a name="what">What is this?</a>
38</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]39<!-- *********************************************************************** -->
40
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]41<div class="doc_text">
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]42
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]43<p>This document is meant to be a sort of "big TODO list" for LLVM. Each
44project in this document is something that would be useful for LLVM to have, and
45would also be a great way to get familiar with the system. Some of these
46projects are small and self-contained, which may be implemented in a couple of
47days, others are larger. Several of these projects may lead to interesting
48research projects in their own right. In any case, we welcome all
49contributions.</p>
50
51<p>If you are thinking about tackling one of these projects, please send a mail
52to the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]53Developer's</a> mailing list, so that we know the project is being worked on.
54Additionally this is a good way to get more information about a specific project
Alkis Evlogimenos45ff0272004-03-11 02:50:35 +0000[diff] [blame]55or to suggest other projects to add to this page.
56</p>
57
Misha Brukman836db502004-05-12 18:57:54 +0000[diff] [blame]58<p>The projects in this page are open-ended. More specific projects are
59filed as unassigned enhancements in the <a href="http://llvm.cs.uiuc.edu/bugs/">
Chris Lattner9f57b182004-05-23 20:29:35 +0000[diff] [blame^]60LLVM bug tracker</a>. See the <a href="http://llvm.cs.uiuc.edu/bugs/buglist.cgi?keywords_type=allwords&amp;keywords=&amp;bug_status=NEW&amp;bug_status=ASSIGNED&amp;bug_status=REOPENED&amp;bug_severity=enhancement&amp;emailassigned_to1=1&amp;emailtype1=substring&amp;email1=unassigned">list of currently outstanding issues</a> if you wish to help improve LLVM.</p>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]61
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]62</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]63
64<!-- *********************************************************************** -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]65<div class="doc_section">
66 <a name="improving">Improving the current system</a>
67</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]68<!-- *********************************************************************** -->
69
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]70<div class="doc_text">
71
72<p>Improvements to the current infrastructure are always very welcome and tend
73to be fairly straight-forward to implement. Here are some of the key areas that
74can use improvement...</p>
75
76</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]77
78<!-- ======================================================================= -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]79<div class="doc_subsection">
80 <a name="glibc">Port glibc to LLVM</a>
81</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]82
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]83<div class="doc_text">
84
85<p>It would be very useful to <a
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]86href="http://www.gnu.org/software/libc/porting.html">port</a> <a
87href="http://www.gnu.org/software/glibc/">glibc</a> to LLVM. This would allow a
88variety of interprocedural algorithms to be much more effective in the face of
89library calls. The most important pieces to port are things like the string
90library and the <tt>stdio</tt> related functions... low-level system calls like
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]91'<tt>read</tt>' should stay unimplemented in LLVM.</p>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]92
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]93</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]94
95<!-- ======================================================================= -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]96<div class="doc_subsection">
97 <a name="NightlyTest">Improving the Nightly Tester</a>
98</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]99
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]100<div class="doc_text">
101
102<p>The <a href="/testresults/">Nightly Tester</a> is a simple perl script
103(located in <tt>utils/NightlyTest.pl</tt>) which runs every night to generate a
104daily report. It could use the following improvements:</p>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]105
106<ol>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]107<li>Regression tests - We should run the regression tests in addition to the
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]108 program tests...</li>
109</ol>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]110
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]111</div>
Chris Lattner1b360042003-02-07 19:25:35 +0000[diff] [blame]112
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]113<!-- ======================================================================= -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]114<div class="doc_subsection">
115 <a name="programs">Compile programs with the LLVM Compiler</a>
116</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]117
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]118<div class="doc_text">
119
120<p>We are always looking for new testcases and benchmarks for use with LLVM. In
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]121particular, it is useful to try compiling your favorite C source code with LLVM.
122If it doesn't compile, try to figure out why or report it to the <a
123href="http://mail.cs.uiuc.edu/pipermail/llvmbugs/">llvm-bugs</a> list. If you
124get the program to compile, it would be extremely useful to convert the build
125system to be compatible with the LLVM Programs testsuite so that we can check it
Chris Lattner1b360042003-02-07 19:25:35 +0000[diff] [blame]126into CVS and the automated tester can use it to track progress of the
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]127compiler.</p>
Chris Lattner1b360042003-02-07 19:25:35 +0000[diff] [blame]128
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]129<p>When testing a code, try running it with a variety of optimizations, and with
130all the back-ends: CBE, llc, and lli.</p>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]131
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]132</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]133
134<!-- ======================================================================= -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]135<div class="doc_subsection">
136 <a name="llvm_ir">Extend the LLVM intermediate representation</a>
137</div>
138
139<div class="doc_text">
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]140
141<ol>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]142<li>Add support for platform-independent prefetch support. The GCC <a
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]143 href="http://gcc.gnu.org/projects/prefetch.html">prefetch project</a> page
144 has a good survey of the prefetching capabilities of a variety of modern
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]145 processors.</li>
146
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]147</ol>
148
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]149</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]150
151<!-- ======================================================================= -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]152<div class="doc_subsection">
153 <a name="misc_imp">Miscellaneous Improvements</a>
154</div>
155
156<div class="doc_text">
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]157
158<ol>
Chris Lattner8bde96f2003-05-06 20:47:11 +0000[diff] [blame]159<li>Someone needs to look into getting the <tt>ranlib</tt> tool to index LLVM
160 bytecode files, so that linking in .a files is not hideously slow. They
161 would also then have to implement the reader for this index in
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]162 <tt>gccld</tt>.</li>
Chris Lattner8bde96f2003-05-06 20:47:11 +0000[diff] [blame]163
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]164<li>Rework the PassManager to be more flexible</li>
165
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]166<li>Some transformations and analyses only work on reducible flow graphs. It
167would be nice to have a transformation which could be "required" by these passes
168which makes irreducible graphs reducible. This can easily be accomplished
169through code duplication. See <a
170href="http://citeseer.nj.nec.com/janssen97making.html">Making Graphs Reducible
171with Controlled Node Splitting</a> and perhaps <a
172href="http://doi.acm.org/10.1145/262004.262005">Nesting of Reducible and
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]173Irreducible Loops</a>.</li>
174
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]175</ol>
176
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]177</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]178
179<!-- *********************************************************************** -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]180<div class="doc_section">
181 <a name="new">Adding new capabilities to LLVM</a>
182</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]183<!-- *********************************************************************** -->
184
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]185<div class="doc_text">
186
Brian Gaeke2d261352004-04-07 15:31:23 +0000[diff] [blame]187<p>Sometimes creating new things is more fun than improving existing things.
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]188These projects tend to be more involved and perhaps require more work, but can
189also be very rewarding.</p>
190
191</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]192
193<!-- ======================================================================= -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]194<div class="doc_subsection">
195 <a name="pointeranalysis">Pointer and Alias Analysis</a>
196</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]197
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]198<div class="doc_text">
199
200<p>We have a <a href="AliasAnalysis.html">strong base for development</a> of
201both pointer analysis based optimizations as well as pointer analyses
202themselves. It seems natural to want to take advantage of this...</p>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]203
204<ol>
205<li>Implement a flow-sensitive context-sensitive alias analysis algorithm<br>
206 - Pick one of the somewhat efficient algorithms, but strive for maximum
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]207 precision</li>
208
Chris Lattnerf56703b2003-06-25 14:31:06 +0000[diff] [blame]209<li>Implement a flow-sensitive context-insensitive alias analysis algorithm<br>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]210 - Just an efficient local algorithm perhaps?</li>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]211
212<li>Implement an interface to update analyses in response to common code motion
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]213 transformations</li>
214
215<li>Implement alias-analysis-based optimizations:
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]216 <ul>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]217 <li>Dead store elimination</li>
218 <li>...</li>
219 </ul></li>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]220</ol>
221
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]222</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]223
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]224<!-- ======================================================================= -->
225<div class="doc_subsection">
226 <a name="profileguided">Profile Guided Optimization</a>
227</div>
228
229<div class="doc_text">
230
Chris Lattnera5422e42004-03-08 22:29:35 +0000[diff] [blame]231<p>We now have a unified infrastructure for writing profile-guided
232transformations, which will work either at offline-compile-time or in the JIT,
233but we don't have many transformations. We would welcome new profile-guided
234transformations as well as improvements to the current profiling system.
235</p>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]236
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]237<p>Ideas for profile guided transformations:</p>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]238
239<ol>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]240<li>Superblock formation (with many optimizations)</li>
241<li>Loop unrolling/peeling</li>
242<li>Profile directed inlining</li>
243<li>Code layout</li>
244<li>...</li>
245</ol>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]246
Chris Lattnera5422e42004-03-08 22:29:35 +0000[diff] [blame]247<p>Improvements to the existing support:</p>
248
249<ol>
250<li>The current block and edge profiling code that gets inserted is very simple
251and inefficient. Through the use of control-dependence information, many fewer
252counters could be inserted into the code. Also, if the execution count of a
253loop is known to be a compile-time or runtime constant, all of the counters in
254the loop could be avoided.</li>
255
256<li>You could implement one of the "static profiling" algorithms which analyze a
257piece of code an make educated guesses about the relative execution frequencies
258of various parts of the code.</li>
259
260<li>You could add path profiling support, or adapt the existing LLVM path
261profiling code to work with the generic profiling interfaces.</li>
262</ol>
263
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]264</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]265
266<!-- ======================================================================= -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]267<div class="doc_subsection">
268 <a name="xforms">New Transformations and Analyses</a>
269</div>
270
271<div class="doc_text">
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]272
273<ol>
274<li>Implement a Dependence Analysis Infrastructure<br>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]275 - Design some way to represent and query dep analysis</li>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]276<li>Implement a strength reduction pass</li>
277<li>Value range propagation pass</li>
278<li>Implement an unswitching pass</li>
279<li>Write a loop unroller, with a simple heuristic for when to unroll</li>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]280</ol>
281
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]282</div>
283
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]284<!-- ======================================================================= -->
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]285<div class="doc_section">
286 <a name="x86be">X86 Back-end Improvements</a>
287</div>
288
289<div class="doc_text">
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]290
291<ol>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]292<li>Implement a better instruction selector</li>
Chris Lattner99df25f2003-04-28 03:42:31 +0000[diff] [blame]293<li>Implement support for the "switch" instruction without requiring the
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]294 lower-switches pass.</li>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]295</ol>
296
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]297</div>
298
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]299<!-- ======================================================================= -->
Misha Brukman3497ae92004-03-11 21:26:29 +0000[diff] [blame]300<div class="doc_section">
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]301 <a name="misc_new">Miscellaneous Additions</a>
302</div>
303
304<div class="doc_text">
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]305
306<ol>
Brian Gaeke2d261352004-04-07 15:31:23 +0000[diff] [blame]307<li>Port the <A HREF="http://www-sop.inria.fr/mimosa/fp/Bigloo/">Bigloo</A>
308Scheme compiler, from Manuel Serrano at INRIA Sophia-Antipolis, to
309output LLVM bytecode. It seems that it can already output .NET
310bytecode, JVM bytecode, and C, so LLVM would ostensibly be another good
311candidate.</li>
312<li>Write a new frontend for some other language (Java? OCaml? Forth?)</li>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]313<li>Write a new backend for a target (IA64? MIPS? MMIX?)</li>
Misha Brukmandec8cfb2004-04-16 16:55:30 +0000[diff] [blame]314<li>Write a disassembler for machine code that would use TableGen to output
315<tt>MachineInstr</tt>s for transformations, optimizations, etc.</li>
Brian Gaekea2245a32004-03-10 19:15:50 +0000[diff] [blame]316<li>Random test vector generator: Use a C grammar to generate random C code;
317run it through llvm-gcc, then run a random set of passes on it using opt.
318Try to crash opt. When opt crashes, use bugpoint to reduce the test case and
319mail the result to yourself. Repeat ad infinitum.</li>
Misha Brukman1a49bc82004-03-10 19:22:29 +0000[diff] [blame]320<li>Design a simple, recognizable logo.</li>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]321</ol>
322
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]323</div>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]324
325<!-- *********************************************************************** -->
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]326
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]327<hr>
Misha Brukman836db502004-05-12 18:57:54 +0000[diff] [blame]328<address>
329 <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
330 src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
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333
334 <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
335 <a href="http://llvm.cs.uiuc.edu">LLVM Compiler Infrastructure</a><br>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]336 Last modified: $Date$
Misha Brukman836db502004-05-12 18:57:54 +0000[diff] [blame]337</address>
Misha Brukman076438b2003-11-14 17:34:38 +0000[diff] [blame]338
339</body>
340</html>