New optimization and interface for either automatically or manually vectorizing Java programs with SSE instructions

The patch file "javavect.patch" for DRLVM provides new features for vectorizing Java programs either automatically or manually. The work consists of four parts:

1) IR extension for vector types and operators (middle-end);
2) vector instruction (SSE) description and code generation (back-end);
3) optimization pass of automatic vectorization for loops (middle-end);
4) Java vector interface (JVI, see below) translator for manually writing vectorized Java programs with JVI (front-end).

Parts 1) and 2) provides the basic facility for internally representing vectorized code and generating SSE instructions. Based on that, part 3) provides an automatic approach and part 4) provides a manual approach for vectorizing Java programs.

The patch file "jvi.patch" for vmmagic provides a Java class library for programmers to write vectorized Java program explicitly. It contains 6 classes representing the types of vectors of 8-, 16-, 32- and 64-bit integers, and 32- and 64-bit floating point numbers. Each class contains appropriate methods representing supported vector operators on that type. The JVI class references and method callings in a Java program are translated into appropriate internal vector IR by the extended front-end, i.e. the work of part 4).

The Java source file "jvi_basic.java" provides a simple test suite for JVI, covering all implemented JVI operations. It can also be used as examples of the usage of JVI.

• • • • Hardware requirement ****

X86 or X86_64 with SSE4.2 instruction set

• • • • Usage of automatic vectorization ****

The patch file contains two new configuration files: server_autovect.emconf and server_static_autovect.emconf, which are copied from server.emconf and servre_static.emconf, and inserted "autovect" optimization pass into their optimization paths. To try automatic vectorization, only need to add one of the following arguments: "-Xem:server_autovect" or "-Xem:server_static_autovect" to run the VM.

• • • • Usage of JVI ****

Write programs with JVI (see jvi_basic.java), compile them and run them with the argument "-Xem:server_static" (This is must because the JVI code cannot be executed without being translated into the vector IR by Jitrino's optimizing compiler).

• • • • Performance improvement ****

The performance of two computation intensive workloads (LU and FFT) is improved by 30% to 100%.

• • • • Testing of the patch based on the Harmony revision 935818 (2010-04-20) ****

Automatic vectorization testing with SPECjvm2008:

• Argument: -Xem:server_static_autovect
• On 64-bit linux machine: All workloads except crypto.aes, derby and xml.transform have passed.
• On 32-bit linux machine: All workloads except derby have passed.
• All the above failed workloads also fail when autovect is disabled (-Xem:server_static), meaning that the failures are caused by bugs of the original code base.

• Argument: -Xem:server_autovect
• On both 64-bit and 32-bit linux machines: All workloads except xml.transform and serial have passed.
• All the above failed workloads also fail when autovect is disabled (-Xem:server), meaning that the failures are caused by bugs of the original code base.

JVI-based vectorization testing with jvi_basic.java:

• Argument: -Xem:server_static
• On both 64-bit and 32-bit linux machines: all test cases have passed.