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| <a href="http://llvm.org/">LLVM Home</a> | |
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| <a href="http://llvm.org/devmtg/">August 1, 2008 - LLVM/Clang Developer Meeting</a> | |
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| <h1>Open VMKit Projects</h1> | |
| <p>Here are a few tasks that are available for newcomers to work on, depending | |
| on what your interests are. This list is provided to generate ideas, it is not | |
| intended to be comprehensive. Please ask on llvm-dev for more specifics. </p> | |
| <ul> | |
| <li><b>Port MMTk to LLVM</b>: | |
| MMTk is JikesRVM's Garbage Collection framework (http://jikesrvm.org) and | |
| contains a number of GC implementations that should be independent of the VM. | |
| MMTk is written in Java, so it is not straightforward to link it with LLVM. | |
| Fortunately, VMKit recently started support of an ahead of time compiler for | |
| Java and should be able to compile MMTk to a .ll file and link with C/C++ | |
| projects. | |
| </li> | |
| <li><b>Support copying collectors in VMKit</b>: | |
| VMKit currently has support for conservative GCs (Boehm and Mmap2) which do not | |
| cooperate with the compiler and thus do not know if a value in the stack is a | |
| pointer or not. If we want to support copying collectors we need to use LLVM's | |
| API on garbage collection (http://llvm.org/docs/GarbageCollection.html) and | |
| modify VMKit's codebase to track uses of GC objects.</li> | |
| <li><b>Port VMKit's JVM to Harmony or OpenJDK</b>: | |
| VMKit currently uses GNU Classpath for the standard Java classes. Interfacing | |
| with another library such as Apache Harmony (http://harmony.apache.org) or | |
| Sun's OpenJDK (http://openjdk.java.net) may help improving support for latest | |
| benchmarks (http://www.spec.org/jvm2008).</li> | |
| </ul> | |
| <p> | |
| On the LLVM side, here are a few interesting projects that would help VMKit: | |
| </p> | |
| <ul> | |
| <li><b>Adaptive Optimization System</b>: | |
| Being able to adaptively optimize JIT-compiled code would dramastically help | |
| the startup time of VMKit. All the non-adaptive bits are already there in LLVM: | |
| baseline compiler (with the -fast command line and the simple register | |
| allocator), optimized compiler (with the linear scan register allocator), and | |
| a full set of optimizations changeable at runtime. What's left is a system that | |
| dynamically lookup the hotness of methods and re-compile with optimizations the | |
| methods that are often executed. | |
| </li> | |
| <li><b>Type-based alias-analysis</b>: | |
| Safe languages such as ones supported by VMKit (Java, C#) benefit a lot from | |
| a type based alias analysis. LLVM currently lacks full support of this feature | |
| for safe languages. | |
| </li> | |
| <li><b>Misceallenous Java-related optimizations</b>: | |
| Removal of array bounds checks, null pointer checks, devirtualization, | |
| inlining, etc. | |
| </li> | |
| </ul> | |
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