mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-11-24 11:42:57 +01:00
327 lines
11 KiB
HTML
327 lines
11 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
|
|
"http://www.w3.org/TR/html4/strict.dtd">
|
|
<html>
|
|
<head>
|
|
<title>Open LLVM Projects</title>
|
|
<link rel="stylesheet" href="llvm.css" type="text/css">
|
|
</head>
|
|
<body>
|
|
|
|
<div class="doc_title">
|
|
Open LLVM Projects
|
|
</div>
|
|
|
|
<ul>
|
|
<li><a href="#what">What is this?</a></li>
|
|
<li><a href="#improving">Improving the current system</a>
|
|
<ol>
|
|
<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="#misc_imp">Miscellaneous Improvements</a></li>
|
|
</ol></li>
|
|
|
|
<li><a href="#new">Adding new capabilities to LLVM</a>
|
|
<ol>
|
|
<li><a href="#pointeranalysis">Pointer and Alias Analysis</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_section">
|
|
<a name="what">What is this?</a>
|
|
</div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>This document is meant to be a sort of "big TODO list" for LLVM. Each
|
|
project in this document is something that would be useful for LLVM to have, and
|
|
would also be a great way to get familiar with the system. Some of these
|
|
projects are small and self-contained, which may be implemented in a couple of
|
|
days, others are larger. Several of these projects may lead to interesting
|
|
research projects in their own right. In any case, we welcome all
|
|
contributions.</p>
|
|
|
|
<p>If you are thinking about tackling one of these projects, please send a mail
|
|
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>
|
|
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section">
|
|
<a name="improving">Improving the current system</a>
|
|
</div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>Improvements to the current infrastructure are always very welcome and tend
|
|
to be fairly straight-forward to implement. Here are some of the key areas that
|
|
can use improvement...</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="glibc">Port glibc to LLVM</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>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="NightlyTest">Improving the Nightly Tester</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>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="programs">Compile programs with the LLVM Compiler</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>We are always looking for new testcases and benchmarks for use with LLVM. In
|
|
particular, it is useful to try compiling your favorite C source code with LLVM.
|
|
If it doesn't compile, try to figure out why or report it to the <a
|
|
href="http://mail.cs.uiuc.edu/pipermail/llvmbugs/">llvm-bugs</a> list. If you
|
|
get the program to compile, it would be extremely useful to convert the build
|
|
system to be compatible with the LLVM Programs testsuite so that we can check it
|
|
into CVS and the automated tester can use it to track progress of the
|
|
compiler.</p>
|
|
|
|
<p>When testing a code, try running it with a variety of optimizations, and with
|
|
all the back-ends: CBE, llc, and lli.</p>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="llvm_ir">Extend the LLVM intermediate representation</a>
|
|
</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
|
|
processors.</li>
|
|
|
|
</ol>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="misc_imp">Miscellaneous Improvements</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ol>
|
|
<li>Someone needs to look into getting the <tt>ranlib</tt> tool to index LLVM
|
|
bytecode files, so that linking in .a files is not hideously slow. They
|
|
would also then have to implement the reader for this index in
|
|
<tt>gccld</tt>.</li>
|
|
|
|
<li>Rework the PassManager to be more flexible</li>
|
|
|
|
<li>Some transformations and analyses only work on reducible flow graphs. It
|
|
would be nice to have a transformation which could be "required" by these passes
|
|
which makes irreducible graphs reducible. This can easily be accomplished
|
|
through code duplication. See <a
|
|
href="http://citeseer.nj.nec.com/janssen97making.html">Making Graphs Reducible
|
|
with Controlled Node Splitting</a> and perhaps <a
|
|
href="http://doi.acm.org/10.1145/262004.262005">Nesting of Reducible and
|
|
Irreducible Loops</a>.</li>
|
|
|
|
</ol>
|
|
|
|
</div>
|
|
|
|
<!-- *********************************************************************** -->
|
|
<div class="doc_section">
|
|
<a name="new">Adding new capabilities to LLVM</a>
|
|
</div>
|
|
<!-- *********************************************************************** -->
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>Sometimes creating new things is more fun that 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="pointeranalysis">Pointer and Alias Analysis</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>We have a <a href="AliasAnalysis.html">strong base for development</a> of
|
|
both pointer analysis based optimizations as well as pointer analyses
|
|
themselves. It seems natural to want to take advantage of this...</p>
|
|
|
|
<ol>
|
|
<li>Implement a flow-sensitive context-sensitive alias analysis algorithm<br>
|
|
- Pick one of the somewhat efficient algorithms, but strive for maximum
|
|
precision</li>
|
|
|
|
<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>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="profileguided">Profile Guided Optimization</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<p>We now have a unified infrastructure for writing profile-guided
|
|
transformations, which will work either at offline-compile-time or in the JIT,
|
|
but we don't have many transformations. We would welcome new profile-guided
|
|
transformations as well as improvements to the current profiling system.
|
|
</p>
|
|
|
|
<p>Ideas for profile guided transformations:</p>
|
|
|
|
<ol>
|
|
<li>Superblock formation (with many optimizations)</li>
|
|
<li>Loop unrolling/peeling</li>
|
|
<li>Profile directed inlining</li>
|
|
<li>Code layout</li>
|
|
<li>...</li>
|
|
</ol>
|
|
|
|
<p>Improvements to the existing support:</p>
|
|
|
|
<ol>
|
|
<li>The current block and edge profiling code that gets inserted is very simple
|
|
and inefficient. Through the use of control-dependence information, many fewer
|
|
counters could be inserted into the code. Also, if the execution count of a
|
|
loop is known to be a compile-time or runtime constant, all of the counters in
|
|
the loop could be avoided.</li>
|
|
|
|
<li>You could implement one of the "static profiling" algorithms which analyze a
|
|
piece of code an make educated guesses about the relative execution frequencies
|
|
of various parts of the code.</li>
|
|
|
|
<li>You could add path profiling support, or adapt the existing LLVM path
|
|
profiling code to work with the generic profiling interfaces.</li>
|
|
</ol>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<a name="xforms">New Transformations and Analyses</a>
|
|
</div>
|
|
|
|
<div class="doc_text">
|
|
|
|
<ol>
|
|
<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_section">
|
|
<a name="x86be">X86 Back-end Improvements</a>
|
|
</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>
|
|
</ol>
|
|
|
|
</div>
|
|
|
|
<!-- ======================================================================= -->
|
|
<div class="doc_subsection">
|
|
<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>Write a new backend for a target (IA64? MIPS? MMIX?)</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>
|
|
Last modified: $Date$
|
|
</div>
|
|
|
|
</body>
|
|
</html>
|