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2<html><head><title>Open LLVM Projects</title></head>
3
4<body bgcolor=white>
5<center><h1><font size=7>Open LLVM Projects</font></h1></center>
6
7<ul>
8 <li><a href="#what">What is this?</a>
9 <li><a href="#improving">Improving the current system</a>
10 <ol>
11 <li><a href="#glibc">Port glibc to LLVM</a>
12 <li><a href="#NightlyTest">Improving the Nightly Tester</a>
13 <li><a href="#programs">Compile programs with the LLVM Compiler</a>
14 <li><a href="#llvm_ir">Extend the LLVM intermediate representation</a>
15 <li><a href="#misc_imp">Miscellaneous Improvements</a>
16 </ol>
17
18 <li><a href="#new">Adding new capabilities to LLVM</a>
19 <ol>
20 <li><a href="#pointeranalysis">Pointer and Alias Analysis</a>
21 <li><a href="#profileguided">Profile Guided Optimization</a>
22 <li><a href="#xforms">New Transformations and Analyses</a>
23 <li><a href="#x86be">X86 Back-end Improvements</a>
24 <li><a href="#misc_new">Miscellaneous Additions</a>
25 </ol>
26</ul>
27
28<br><br>
29
30<!-- *********************************************************************** -->
31<table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
32<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
33<a name="what">What is this?
34</b></font></td></tr></table><ul>
35<!-- *********************************************************************** -->
36
37This document is meant to be a sort of "big TODO list" for LLVM. Each project
38in this document is something that would be useful for LLVM to have, and would
39also be a great way to get familiar with the system. Some of these projects are
40small and self-contained, which may be implemented in a couple of days, others
41are larger. Several of these projects may lead to interesting research projects
42in their own right. In any case, we welcome all contributions.<p>
43
44If you are thinking about tackling one of these projects, please send a mail to
45the <a href="http://mail.cs.uiuc.edu/mailman/listinfo/llvmdev">LLVM
46Developer's</a> mailing list, so that we know the project is being worked on.
47Additionally this is a good way to get more information about a specific project
48or to suggest other projects to add to this page.<p>
49
50
51<!-- *********************************************************************** -->
52</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
53<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
54<a name="improving">Improving the current system
55</b></font></td></tr></table><ul>
56<!-- *********************************************************************** -->
57
58Improvements to the current infrastructure are always very welcome and tend to
59be fairly straight-forward to implement. Here are some of the key areas that
60can use improvement...<p>
61
62<!-- ======================================================================= -->
63</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
64<tr><td>&nbsp;</td><td width=100%>&nbsp;
65<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
66<a name="glibc">Port glibc to LLVM
67</b></font></td></tr></table><ul>
68
69It would be very useful to <a
70href="http://www.gnu.org/software/libc/porting.html">port</a> <a
71href="http://www.gnu.org/software/glibc/">glibc</a> to LLVM. This would allow a
72variety of interprocedural algorithms to be much more effective in the face of
73library calls. The most important pieces to port are things like the string
74library and the <tt>stdio</tt> related functions... low-level system calls like
75'<tt>read</tt>' should stay unimplemented in LLVM.<p>
76
77
78<!-- ======================================================================= -->
79</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
80<tr><td>&nbsp;</td><td width=100%>&nbsp;
81<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
82<a name="NightlyTest">Improving the Nightly Tester
83</b></font></td></tr></table><ul>
84
85The <a href="/testresults/">Nightly Tester</a> is a simple perl script (located
86in utils/NightlyTest.pl) which runs every night to generate a daily report. It
87could use the following improvements:<p>
88
89<ol>
90<li>Olden timings - Time the compilation and execution times for the Olden
91 benchmark suite, keeping track of these values over time.
92
93<li>Graphs - It would be great to have gnuplot graphs to keep track of how the
94 tree is changing over time. We already gather a several statistics, it
95 just neccesary to add the script-fu to gnuplotize it.
96
97<li>Regression tests - We should run the regression tests in addition to the
98 program tests...
99</ol><p>
100
Chris Lattner1b360042003-02-07 19:25:35 +0000[diff] [blame]101
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]102<!-- ======================================================================= -->
103</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
104<tr><td>&nbsp;</td><td width=100%>&nbsp;
105<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
106<a name="programs">Compile programs with the LLVM Compiler
107</b></font></td></tr></table><ul>
108
109We are always looking for new testcases and benchmarks for use with LLVM. In
110particular, it is useful to try compiling your favorite C source code with LLVM.
111If it doesn't compile, try to figure out why or report it to the <a
112href="http://mail.cs.uiuc.edu/pipermail/llvmbugs/">llvm-bugs</a> list. If you
113get the program to compile, it would be extremely useful to convert the build
114system to be compatible with the LLVM Programs testsuite so that we can check it
Chris Lattner1b360042003-02-07 19:25:35 +0000[diff] [blame]115into CVS and the automated tester can use it to track progress of the
116compiler.<p>
117
118When testing a code, try running it with a variety of optimizations, and with
119all the back-ends: CBE, llc, and lli.<p>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]120
121
122<!-- ======================================================================= -->
123</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
124<tr><td>&nbsp;</td><td width=100%>&nbsp;
125<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
126<a name="llvm_ir">Extend the LLVM intermediate representation
127</b></font></td></tr></table><ul>
128
129<ol>
130<li>Transform <tt>setjmp</tt> and <tt>longjmp</tt> calls to use the LLVM
131 <tt>invoke</tt> mechanism.
132<li>Add support for a volatile attribute on loads and stores
133<li>Support for variable argument functions
134<li>Add a new conditional move instruction: <tt>X = select bool Cond, Y, Z</tt>
Misha Brukman3d87b422003-03-08 23:59:05 +0000[diff] [blame]135<li>Add support for platform independent prefetch support. The GCC <a
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]136 href="http://gcc.gnu.org/projects/prefetch.html">prefetch project</a> page
137 has a good survey of the prefetching capabilities of a variety of modern
138 processors.
139</ol>
140
141
142<!-- ======================================================================= -->
143</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
144<tr><td>&nbsp;</td><td width=100%>&nbsp;
145<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
146<a name="misc_imp">Miscellaneous Improvements
147</b></font></td></tr></table><ul>
148
149<ol>
Chris Lattner8bde96f2003-05-06 20:47:11 +0000[diff] [blame^]150<li>Someone needs to look into getting the <tt>ranlib</tt> tool to index LLVM
151 bytecode files, so that linking in .a files is not hideously slow. They
152 would also then have to implement the reader for this index in
153 <tt>gccld</tt>.<br>
154
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]155<li>Improve the efficiency of the bytecode loader/writer, allow streaming lazy
156 loading of functions from the bytecode (for use by the JIT, for example)<br>
Chris Lattner99df25f2003-04-28 03:42:31 +0000[diff] [blame]157<li>Rework the PassManager to be more flexible
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]158<li>Some transformations and analyses only work on reducible flow graphs. It
159would be nice to have a transformation which could be "required" by these passes
160which makes irreducible graphs reducible. This can easily be accomplished
161through code duplication. See <a
162href="http://citeseer.nj.nec.com/janssen97making.html">Making Graphs Reducible
163with Controlled Node Splitting</a> and perhaps <a
164href="http://doi.acm.org/10.1145/262004.262005">Nesting of Reducible and
165Irreducible Loops</a>.
166</ol>
167
168
169<!-- *********************************************************************** -->
170</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
171<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
172<a name="new">Adding new capabilities to LLVM
173</b></font></td></tr></table><ul>
174<!-- *********************************************************************** -->
175
176Sometimes creating new things is more fun that improving existing things. These
177projects tend to be more involved and perhaps require more work, but can also be
178very rewarding.<p>
179
180<!-- ======================================================================= -->
181</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
182<tr><td>&nbsp;</td><td width=100%>&nbsp;
183<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
184<a name="pointeranalysis">Pointer and Alias Analysis
185</b></font></td></tr></table><ul>
186
187We have a strong base for development of both pointer analysis based
188optimizations as well as pointer analyses themselves. It seems natural to want
189to take advantage of this...<p>
190
191<ol>
192<li>Implement a flow-sensitive context-sensitive alias analysis algorithm<br>
193 - Pick one of the somewhat efficient algorithms, but strive for maximum
194 precision
195<li>Implement a flow-sensitive context-insensitive alias anlaysis algorithm<br>
196 - Just an efficient local algorithm perhaps?
197
198<li>Implement an interface to update analyses in response to common code motion
199 transformations
200<li>Implement alias analysis based optimizations:
201 <ul>
202 <li>Dead store elimination
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]203 <li>Store+Reload or "store forwarding" elimination:<p>
204 Change:
205 <pre>
206 store int X, int* P
207 Y = load int* P</pre>
208 into:
209 <pre>
210 store int X, int *P
211 Y = X</pre>
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]212 </ul>
213</ol>
214
215<!-- ======================================================================= -->
216</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
217<tr><td>&nbsp;</td><td width=100%>&nbsp;
218<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
219<a name="profileguided">Profile Guided Optimization
220</b></font></td></tr></table><ul>
221
222We are getting to the point where we really need a unified infrastructure for
223profile guided optimizations. It would be wonderful to be able to write profile
224guided transformations which can be performed either at static compile time
225(compile time or offline optimization time) or at runtime in a JIT type setup.
226The LLVM transformation itself shouldn't need to know how it is being used.<p>
227
228Ideas for profile guided transformations:<p>
229
230<ol>
231<li>Superblock formation (with many optimizations)
232<li>Loop unrolling/peeling
233<li>Profile directed inlining
234<li>Code layout
235<li>...
236</ol><p>
237
238
239<!-- ======================================================================= -->
240</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
241<tr><td>&nbsp;</td><td width=100%>&nbsp;
242<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
243<a name="xforms">New Transformations and Analyses
244</b></font></td></tr></table><ul>
245
246<ol>
247<li>Implement a Dependence Analysis Infrastructure<br>
248 - Design some way to represent and query dep analysis
249<li>Implement a faster Dominator Set Construction Algorithm<br>
250 - A linear time or nearly so algorithm
251<li>Implement a strength reduction pass
252<li>Value range propagation pass
253<li>Implement a tail recursion elimination pass
254<li>Implement an unswitching pass
255</ol>
256
257<!-- ======================================================================= -->
258</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
259<tr><td>&nbsp;</td><td width=100%>&nbsp;
260<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
261<a name="x86be">X86 Back-end Improvements
262</b></font></td></tr></table><ul>
263
264<ol>
265<li>Implement a global register allocator
266<li>Implement a better instruction selector
267<li>Implement a static compiler in addition to the JIT (easy project)
Chris Lattner99df25f2003-04-28 03:42:31 +0000[diff] [blame]268<li>Implement support for the "switch" instruction without requiring the
269 lower-switches pass.
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]270</ol>
271
272<!-- ======================================================================= -->
273</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
274<tr><td>&nbsp;</td><td width=100%>&nbsp;
275<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
276<a name="misc_new">Miscellaneous Additions
277</b></font></td></tr></table><ul>
278
279<ol>
280<li>Write a new frontend for some language (Java? OCaml? Forth?)
281<li>Write a new backend for a target (IA64? MIPS? MMIX?)
282</ol>
283
284
285<!-- *********************************************************************** -->
286</ul>
287<!-- *********************************************************************** -->
288
289<hr><font size-1>
290<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
291<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
292<!-- hhmts start -->
Chris Lattner8bde96f2003-05-06 20:47:11 +0000[diff] [blame^]293Last modified: Tue May 6 15:46:48 CDT 2003
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]294<!-- hhmts end -->
295</font></body></html>