Silicon Graphics, Inc.

Translation to MIPS Code

This JDK release includes support for translating Java bytecode to MIPS machine code and running it instead of the bytecode in order to improve Java runtime performance.

The -jit (Just In Time) option causes java, the Java interpreter, and appletviewer, the Java applet viewer, to do this translation on the code for each class when it is loaded, and then subsequently to use the MIPS code.

The translation to MIPS code is very fast, but if you want to avoid the penalty of doing this translation each time you run your code using java or appletviewer, you can translate the code for a class ahead of time using javat. For any Java .class file, running javat with the name of the class file as an argument will produce a new version of that file which contains MIPS code in addition to the original Java bytecode. Then you can run java or appletviewer with the -tran option to load and use this pre-translated code for all classes that have it. The Java class libraries in /usr/java/classes have already been pre-translated.

For both -jit and -tran there are opposite options that turn off these features, which are -nojit and -notran, respectively. The default is currently -nojit -notran.

Using the -jit and -tran options together causes pre-translated code to be read in from .class files where possible, and causes code in other classes to be translated at load time. You should use both options for maximum performance.

Since class files that are loaded from locations not given in the CLASSPATH environment variable are considered "untrusted", no MIPS code is loaded from them, so the -jit option must be used for their best performance. Under normal operation, this includes all applet code.

MIPS code execution is not available:

Also, support for generating and running MIPS code has not yet been integrated with the SGI version of Netscape, so MIPS code execution is not yet available when running your applets in Netscape.


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