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(gcj-300.info)Code Generation

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Code Generation
===============

   In addition to the many `gcc' options controlling code generation,
`gcj' has several options specific to itself.

`--main=CLASSNAME'
     This option is used when linking to specify the name of the class
     whose `main' method should be invoked when the resulting
     executable is run.  (1)

`-DNAME[=VALUE]'
     This option can only be used with `--main'.  It defines a system
     property named NAME with value VALUE.  If VALUE is not specified
     then it defaults to the empty string.  These system properties are
     initialized at the program's startup and can be retrieved at
     runtime using the `java.lang.System.getProperty' method.

`-C'
     This option is used to tell `gcj' to generate bytecode (`.class'
     files) rather than object code.

`-d DIRECTORY'
     When used with `-C', this causes all generated `.class' files to
     be put in the appropriate subdirectory of DIRECTORY.  By default
     they will be put in subdirectories of the current working
     directory.

`-fno-bounds-check'
     By default, `gcj' generates code which checks the bounds of all
     array indexing operations.  With this option, these checks are
     omitted.  Note that this can result in unpredictable behavior if
     the code in question actually does violate array bounds
     constraints.

`-fjni'
     With `gcj' there are two options for writing native methods: CNI
     and JNI.  By default `gcj' assumes you are using CNI.  If you are
     compiling a class with native methods, and these methods are
     implemented using JNI, then you must use `-fjni'.  This option
     causes `gcj' to generate stubs which will invoke the underlying JNI
     methods.

   ---------- Footnotes ----------

   (1) The linker by default looks for a global function named `main'.
Since Java does not have global functions, and a collection of Java
classes may have more than one class with a `main' method, you need to
let the linker know which of those `main' methods it should invoke when
starting the application.