X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=docs%2FOpenProjects.html;h=ebf28abb728f0f5b174b300fd3218f9b7a33cbe7;hb=4573f1b8cf61890c25f85952221d243e05e5474f;hp=574f4d34d3813bdddc962dff720dd8e7d8e6aaa3;hpb=5560c9d49ccae132cabf1155f18aa0480dce3eda;p=oota-llvm.git diff --git a/docs/OpenProjects.html b/docs/OpenProjects.html index 574f4d34d38..ebf28abb728 100644 --- a/docs/OpenProjects.html +++ b/docs/OpenProjects.html @@ -1,159 +1,172 @@ - -Open LLVM Projects - - -

Open LLVM Projects

+ + + + Open LLVM Projects + + + + +

+ Open LLVM Projects +

What is this? +
What is this?
Improving the current system
+
Implementing Code Cleanup bugs
Port glibc to LLVM
Compile programs with the LLVM Compiler
Extend the LLVM intermediate representation
Miscellaneous Improvements
Adding new capabilities to LLVM
+
Implementing new feature PRs
Pointer and Alias Analysis
Profile Guided Optimization
New Transformations and Analyses
X86 Back-end Improvements
Miscellaneous Additions

-

+

Written by the LLVM Team

+ - -

-What is this? -

+ What is this? +

+ +

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.

-If you are thinking about tackling one of these projects, please send a mail to -the LLVM +

If you are thinking about tackling one of these projects, please send a mail +to the LLVM Developer's 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.

+or to suggest other projects to add to this page. +

The projects in this page are open-ended. More specific projects are +filed as unassigned enhancements in the +LLVM bug tracker. See the list of currently outstanding issues if you wish to help improve LLVM.

+ +

-Improving the current system -

+ Improving the current system +

- -

- -Port glibc to LLVM -

port

glibc

stdio

read

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...

- -Improving the Nightly Tester -

+ Implementing Code Cleanup bugs +

Nightly Tester

Olden timings - Time the compilation and execution times for the Olden - benchmark suite, keeping track of these values over time. +
+The LLVM bug tracker occasionally +has "code-cleanup" bugs filed in it. Taking one of these and fixing it is a good +way to get your feet wet in the LLVM code and discover how some of its components +work. +
+ +

+ Port glibc to LLVM +

Graphs - It would be great to have gnuplot graphs to keep track of how the - tree is changing over time. We already gather a several statistics, it - just necessary to add the script-fu to gnuplotize it. +
-
Regression tests - We should run the regression tests in addition to the - program tests... -
+
It would be very useful to port glibc 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 stdio related functions... low-level system calls like +'read' should stay unimplemented in LLVM.
+ -

- -Compile programs with the LLVM Compiler -

+ Compile programs with the LLVM Compiler +

+ +

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 llvm-bugs 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.

+compiler.

-When testing a code, try running it with a variety of optimizations, and with -all the back-ends: CBE, llc, and lli.

When testing a code, try running it with a variety of optimizations, and with +all the back-ends: CBE, llc, and lli.

- -Extend the LLVM intermediate representation -

+ Extend the LLVM intermediate representation +

Transform setjmp and longjmp calls to use the LLVM - invoke mechanism. -
Add support for a volatile attribute on loads and stores -
Add a new conditional move instruction: X = select bool Cond, Y, Z -
Add support for platform independent prefetch support. The GCC Add support for platform-independent prefetch support. The GCC prefetch project page has a good survey of the prefetching capabilities of a variety of modern - processors. + processors.

- -Miscellaneous Improvements -

+ Miscellaneous Improvements +

Someone needs to look into getting the ranlib 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 - gccld.
+ gccld.
Rework the PassManager to be more flexible
Improve the efficiency of the bytecode loader/writer, allow streaming lazy - loading of functions from the bytecode (for use by the JIT, for example)
-
Rework the PassManager to be more flexible
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 @@ -161,125 +174,182 @@ through code duplication. See Making Graphs Reducible with Controlled Node Splitting and perhaps Nesting of Reducible and -Irreducible Loops. +Irreducible Loops.

-Adding new capabilities to LLVM -

+ Adding new capabilities to LLVM +

+ +

Sometimes creating new things is more fun than improving existing things. +These projects tend to be more involved and perhaps require more work, but can +also be very rewarding.

+ +

- -Pointer and Alias Analysis -

+ Implementing new feature PRs +

strong base for development

+ +

Many ideas for feature requests are stored in LLVM bugzilla. Just search for bugs with a "new-feature" keyword.

+ +

+ Pointer and Alias Analysis +

+ +

We have a strong base for development of +both pointer analysis based optimizations as well as pointer analyses +themselves. It seems natural to want to take advantage of this...

Implement a flow-sensitive context-sensitive alias analysis algorithm
- Pick one of the somewhat efficient algorithms, but strive for maximum - precision + precision
Implement a flow-sensitive context-insensitive alias analysis algorithm
- - Just an efficient local algorithm perhaps? + - Just an efficient local algorithm perhaps?
Implement an interface to update analyses in response to common code motion - transformations -
Implement alias analysis based optimizations: +
Implement alias-analysis-based optimizations:
- Dead store elimination -
+
Dead store elimination
...

+ + - -

- -Profile Guided Optimization -

+ Profile Guided Optimization +

-We are getting to the point where we really need a unified infrastructure for -profile guided optimizations. It would be wonderful to be able to write profile -guided transformations which can be performed either at static compile time -(compile time or offline optimization time) or at runtime in a JIT type setup. -The LLVM transformation itself shouldn't need to know how it is being used.

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. +

-Ideas for profile guided transformations:

Ideas for profile guided transformations:

Superblock formation (with many optimizations) -
Loop unrolling/peeling -
Profile directed inlining -
Code layout -
... -

Superblock formation (with many optimizations)

Loop unrolling/peeling

Profile directed inlining

Code layout

...

+ +

Improvements to the existing support:

+ +

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.
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.
You could add path profiling support, or adapt the existing LLVM path +profiling code to work with the generic profiling interfaces.

+ +

- -New Transformations and Analyses -

+ New Transformations and Analyses +

Implement a Dependence Analysis Infrastructure
- - Design some way to represent and query dep analysis -
Implement a faster Dominator Set Construction Algorithm
- - A linear time or nearly so algorithm -
Implement a strength reduction pass -
Value range propagation pass -
Implement a tail recursion elimination pass -
Implement an unswitching pass -
Write a loop unroller, with a simple heuristic for when to unroll + - Design some way to represent and query dep analysis
Implement a strength reduction pass
Value range propagation pass

- -X86 Back-end Improvements -

+ X86 Back-end Improvements +

Implement a global register allocator -
Implement a better instruction selector +
Implement a better instruction selector
Implement support for the "switch" instruction without requiring the - lower-switches pass. + lower-switches pass.
Implement interprocedural register allocation. The CallGraphSCCPass can be + used to implement a bottom-up analysis that will determine the *actual* + registers clobbered by a function. Use the pass to fine tune register usage + in callers based on *actual* registers used by the callee.

- -Miscellaneous Additions -

+ Miscellaneous Additions +

Write a new frontend for some language (Java? OCaml? Forth?) -
Write a new backend for a target (IA64? MIPS? MMIX?) +
Port the Bigloo +Scheme compiler, from Manuel Serrano at INRIA Sophia-Antipolis, to +output LLVM bytecode. It seems that it can already output .NET +bytecode, JVM bytecode, and C, so LLVM would ostensibly be another good +candidate.
Write a new frontend for some other language (Java? OCaml? Forth?)
Write a new backend for a target (IA64? MIPS? MMIX?)
Write a disassembler for machine code that would use TableGen to output +MachineInstrs for transformations, optimizations, etc.
Random test vector generator: Use a C grammar to generate random C code; +run it through llvm-gcc, then run a random set of passes on it using opt. +Try to crash opt. When opt crashes, use bugpoint to reduce the test case and +mail the result to yourself. Repeat ad infinitum.
Design a simple, recognizable logo.

- -

Chris Lattner

- - -Last modified: Wed Aug 6 10:40:05 CDT 2003 - - +

+ + Chris Lattner
+ LLVM Compiler Infrastructure
+ Last modified: $Date$ +

+ + +