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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>
135<li>Add support for platform independant prefetch support. The GCC <a
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>
150<li>Improve the efficiency of the bytecode loader/writer, allow streaming lazy
151 loading of functions from the bytecode (for use by the JIT, for example)<br>
152<li>Rework the PassManager
153<li>Do not encode zero intializers for large arrays into the bytecode
154
155<li>Some transformations and analyses only work on reducible flow graphs. It
156would be nice to have a transformation which could be "required" by these passes
157which makes irreducible graphs reducible. This can easily be accomplished
158through code duplication. See <a
159href="http://citeseer.nj.nec.com/janssen97making.html">Making Graphs Reducible
160with Controlled Node Splitting</a> and perhaps <a
161href="http://doi.acm.org/10.1145/262004.262005">Nesting of Reducible and
162Irreducible Loops</a>.
163</ol>
164
165
166<!-- *********************************************************************** -->
167</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
168<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
169<a name="new">Adding new capabilities to LLVM
170</b></font></td></tr></table><ul>
171<!-- *********************************************************************** -->
172
173Sometimes creating new things is more fun that improving existing things. These
174projects tend to be more involved and perhaps require more work, but can also be
175very rewarding.<p>
176
177<!-- ======================================================================= -->
178</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
179<tr><td>&nbsp;</td><td width=100%>&nbsp;
180<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
181<a name="pointeranalysis">Pointer and Alias Analysis
182</b></font></td></tr></table><ul>
183
184We have a strong base for development of both pointer analysis based
185optimizations as well as pointer analyses themselves. It seems natural to want
186to take advantage of this...<p>
187
188<ol>
189<li>Implement a flow-sensitive context-sensitive alias analysis algorithm<br>
190 - Pick one of the somewhat efficient algorithms, but strive for maximum
191 precision
192<li>Implement a flow-sensitive context-insensitive alias anlaysis algorithm<br>
193 - Just an efficient local algorithm perhaps?
194
195<li>Implement an interface to update analyses in response to common code motion
196 transformations
197<li>Implement alias analysis based optimizations:
198 <ul>
199 <li>Dead store elimination
200 <li>Location invariant Code Motion (LcICM)
201 <li>Store+Reload or "store forwarding" elimination:<p>
202 Change:
203 <pre>
204 store int X, int* P
205 Y = load int* P</pre>
206 into:
207 <pre>
208 store int X, int *P
209 Y = X</pre>
210 <li>Register promotion (move loads and stores out of loop bodies, for example)
211 </ul>
212</ol>
213
214<!-- ======================================================================= -->
215</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
216<tr><td>&nbsp;</td><td width=100%>&nbsp;
217<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
218<a name="profileguided">Profile Guided Optimization
219</b></font></td></tr></table><ul>
220
221We are getting to the point where we really need a unified infrastructure for
222profile guided optimizations. It would be wonderful to be able to write profile
223guided transformations which can be performed either at static compile time
224(compile time or offline optimization time) or at runtime in a JIT type setup.
225The LLVM transformation itself shouldn't need to know how it is being used.<p>
226
227Ideas for profile guided transformations:<p>
228
229<ol>
230<li>Superblock formation (with many optimizations)
231<li>Loop unrolling/peeling
232<li>Profile directed inlining
233<li>Code layout
234<li>...
235</ol><p>
236
237
238<!-- ======================================================================= -->
239</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
240<tr><td>&nbsp;</td><td width=100%>&nbsp;
241<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
242<a name="xforms">New Transformations and Analyses
243</b></font></td></tr></table><ul>
244
245<ol>
246<li>Implement a Dependence Analysis Infrastructure<br>
247 - Design some way to represent and query dep analysis
248<li>Implement a faster Dominator Set Construction Algorithm<br>
249 - A linear time or nearly so algorithm
250<li>Implement a strength reduction pass
251<li>Value range propagation pass
252<li>Implement a tail recursion elimination pass
253<li>Implement an unswitching pass
254</ol>
255
256<!-- ======================================================================= -->
257</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
258<tr><td>&nbsp;</td><td width=100%>&nbsp;
259<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
260<a name="x86be">X86 Back-end Improvements
261</b></font></td></tr></table><ul>
262
263<ol>
264<li>Implement a global register allocator
265<li>Implement a better instruction selector
266<li>Implement a static compiler in addition to the JIT (easy project)
267</ol>
268
269<!-- ======================================================================= -->
270</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
271<tr><td>&nbsp;</td><td width=100%>&nbsp;
272<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
273<a name="misc_new">Miscellaneous Additions
274</b></font></td></tr></table><ul>
275
276<ol>
277<li>Write a new frontend for some language (Java? OCaml? Forth?)
278<li>Write a new backend for a target (IA64? MIPS? MMIX?)
279</ol>
280
281
282<!-- *********************************************************************** -->
283</ul>
284<!-- *********************************************************************** -->
285
286<hr><font size-1>
287<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
288<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
289<!-- hhmts start -->
Chris Lattner1b360042003-02-07 19:25:35 +0000[diff] [blame^]290Last modified: Fri Feb 7 13:24:26 CST 2003
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame]291<!-- hhmts end -->
292</font></body></html>