Gitiles
Code Review Sign In
gerrit-public.fairphone.software / fp2-dev / platform / external / llvm / b71310982a1782f435e3836c8b9bdc489d4135e2 / . / docs / OpenProjects.html
blob: b79c0aae92e18ae97abe03360d1aeaf43702c1f3 [file] [log] [blame]
Chris Lattnerb7131092003-02-06 19:39:21 +0000[diff] [blame^]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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
101<!-- ======================================================================= -->
102</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
103<tr><td>&nbsp;</td><td width=100%>&nbsp;
104<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
105<a name="programs">Compile programs with the LLVM Compiler
106</b></font></td></tr></table><ul>
107
108We are always looking for new testcases and benchmarks for use with LLVM. In
109particular, it is useful to try compiling your favorite C source code with LLVM.
110If it doesn't compile, try to figure out why or report it to the <a
111href="http://mail.cs.uiuc.edu/pipermail/llvmbugs/">llvm-bugs</a> list. If you
112get the program to compile, it would be extremely useful to convert the build
113system to be compatible with the LLVM Programs testsuite so that we can check it
114into CVS and the automated tester can use it to track progress of the compiler.
115
116
117<!-- ======================================================================= -->
118</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
119<tr><td>&nbsp;</td><td width=100%>&nbsp;
120<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
121<a name="llvm_ir">Extend the LLVM intermediate representation
122</b></font></td></tr></table><ul>
123
124<ol>
125<li>Transform <tt>setjmp</tt> and <tt>longjmp</tt> calls to use the LLVM
126 <tt>invoke</tt> mechanism.
127<li>Add support for a volatile attribute on loads and stores
128<li>Support for variable argument functions
129<li>Add a new conditional move instruction: <tt>X = select bool Cond, Y, Z</tt>
130<li>Add support for platform independant prefetch support. The GCC <a
131 href="http://gcc.gnu.org/projects/prefetch.html">prefetch project</a> page
132 has a good survey of the prefetching capabilities of a variety of modern
133 processors.
134</ol>
135
136
137<!-- ======================================================================= -->
138</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
139<tr><td>&nbsp;</td><td width=100%>&nbsp;
140<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
141<a name="misc_imp">Miscellaneous Improvements
142</b></font></td></tr></table><ul>
143
144<ol>
145<li>Improve the efficiency of the bytecode loader/writer, allow streaming lazy
146 loading of functions from the bytecode (for use by the JIT, for example)<br>
147<li>Rework the PassManager
148<li>Do not encode zero intializers for large arrays into the bytecode
149
150<li>Some transformations and analyses only work on reducible flow graphs. It
151would be nice to have a transformation which could be "required" by these passes
152which makes irreducible graphs reducible. This can easily be accomplished
153through code duplication. See <a
154href="http://citeseer.nj.nec.com/janssen97making.html">Making Graphs Reducible
155with Controlled Node Splitting</a> and perhaps <a
156href="http://doi.acm.org/10.1145/262004.262005">Nesting of Reducible and
157Irreducible Loops</a>.
158</ol>
159
160
161<!-- *********************************************************************** -->
162</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
163<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
164<a name="new">Adding new capabilities to LLVM
165</b></font></td></tr></table><ul>
166<!-- *********************************************************************** -->
167
168Sometimes creating new things is more fun that improving existing things. These
169projects tend to be more involved and perhaps require more work, but can also be
170very rewarding.<p>
171
172<!-- ======================================================================= -->
173</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
174<tr><td>&nbsp;</td><td width=100%>&nbsp;
175<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
176<a name="pointeranalysis">Pointer and Alias Analysis
177</b></font></td></tr></table><ul>
178
179We have a strong base for development of both pointer analysis based
180optimizations as well as pointer analyses themselves. It seems natural to want
181to take advantage of this...<p>
182
183<ol>
184<li>Implement a flow-sensitive context-sensitive alias analysis algorithm<br>
185 - Pick one of the somewhat efficient algorithms, but strive for maximum
186 precision
187<li>Implement a flow-sensitive context-insensitive alias anlaysis algorithm<br>
188 - Just an efficient local algorithm perhaps?
189
190<li>Implement an interface to update analyses in response to common code motion
191 transformations
192<li>Implement alias analysis based optimizations:
193 <ul>
194 <li>Dead store elimination
195 <li>Location invariant Code Motion (LcICM)
196 <li>Store+Reload or "store forwarding" elimination:<p>
197 Change:
198 <pre>
199 store int X, int* P
200 Y = load int* P</pre>
201 into:
202 <pre>
203 store int X, int *P
204 Y = X</pre>
205 <li>Register promotion (move loads and stores out of loop bodies, for example)
206 </ul>
207</ol>
208
209<!-- ======================================================================= -->
210</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
211<tr><td>&nbsp;</td><td width=100%>&nbsp;
212<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
213<a name="profileguided">Profile Guided Optimization
214</b></font></td></tr></table><ul>
215
216We are getting to the point where we really need a unified infrastructure for
217profile guided optimizations. It would be wonderful to be able to write profile
218guided transformations which can be performed either at static compile time
219(compile time or offline optimization time) or at runtime in a JIT type setup.
220The LLVM transformation itself shouldn't need to know how it is being used.<p>
221
222Ideas for profile guided transformations:<p>
223
224<ol>
225<li>Superblock formation (with many optimizations)
226<li>Loop unrolling/peeling
227<li>Profile directed inlining
228<li>Code layout
229<li>...
230</ol><p>
231
232
233<!-- ======================================================================= -->
234</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
235<tr><td>&nbsp;</td><td width=100%>&nbsp;
236<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
237<a name="xforms">New Transformations and Analyses
238</b></font></td></tr></table><ul>
239
240<ol>
241<li>Implement a Dependence Analysis Infrastructure<br>
242 - Design some way to represent and query dep analysis
243<li>Implement a faster Dominator Set Construction Algorithm<br>
244 - A linear time or nearly so algorithm
245<li>Implement a strength reduction pass
246<li>Value range propagation pass
247<li>Implement a tail recursion elimination pass
248<li>Implement an unswitching pass
249</ol>
250
251<!-- ======================================================================= -->
252</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
253<tr><td>&nbsp;</td><td width=100%>&nbsp;
254<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
255<a name="x86be">X86 Back-end Improvements
256</b></font></td></tr></table><ul>
257
258<ol>
259<li>Implement a global register allocator
260<li>Implement a better instruction selector
261<li>Implement a static compiler in addition to the JIT (easy project)
262</ol>
263
264<!-- ======================================================================= -->
265</ul><table width="50%" bgcolor="#441188" border=0 cellpadding=4 cellspacing=0>
266<tr><td>&nbsp;</td><td width=100%>&nbsp;
267<font color="#EEEEFF" size=+1 face="Georgia,Palatino"><b>
268<a name="misc_new">Miscellaneous Additions
269</b></font></td></tr></table><ul>
270
271<ol>
272<li>Write a new frontend for some language (Java? OCaml? Forth?)
273<li>Write a new backend for a target (IA64? MIPS? MMIX?)
274</ol>
275
276
277<!-- *********************************************************************** -->
278</ul>
279<!-- *********************************************************************** -->
280
281<hr><font size-1>
282<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
283<!-- Created: Tue Aug 6 15:00:33 CDT 2002 -->
284<!-- hhmts start -->
285Last modified: Thu Feb 6 13:38:41 CST 2003
286<!-- hhmts end -->
287</font></body></html>