Initialization of static data in Java

Thu Nov 19 15:12:00 GMT 1998

> The example I was illustrating was a `private static final byte' array.

This is not necessarily read-only. You basically have to verify
that no method modifies any element, and that the array is not
passed to any method (which might modify it). This is not difficult,
of course. And a side benefit is that you don't have to actually
create/manage a Java object - because all references are known,
you can treat it as a C array (without the Java array header).
If you cannot do this, or the array is non-private, or the
array is non-static, you have to allocate it dynamically, but it
still wins to initialize the array from a static read-only buffer,
using memcpy (as you mention).
> Currently, if you give gcj that java/lang/Character.class
> file, it runs out of virtual memory trying to optimize all the table
> initialization. 

Well, since we can't use Sun's classes.zip class for legal reasons,
and don't want to for technical reasons, I don't think it really
matter - for this specific class. Still, we do want to handle
large arrays - however, handling Java source well is the first
priority. We'll get to it, but i don't know when. (These arrays
used to be handled even worse. However, I put in some hooks so
that at least we don't emit useless code for bounds checking
in these cases. That makes running out of virtual memory less
likely, but it is still handled inefficienty by gcc.)
	--Per Bothner
Cygnus Solutions bothner@cygnus.com http://www.cygnus.com/~bothner