On Fri, 28 Feb 2003, Dalibor Topic wrote: > hi Chris, > > --- Chris Gray <[EMAIL PROTECTED]> wrote: > > [...] SFAIK the only > > legitimate inlining a > > bytecode compiler can do is for static final > > constants. > > I doubt even that is safe, as > http://java.sun.com/j2se/1.4/docs/api/java/awt/event/MouseEvent.html#MOUSE_LAST > this field surely changed between the java releases > when they introduced mouse wheel support ;)
Nonetheless, javac certainly used to do that, and I'm pretty sure it still does. (I could swear that the JLS actually specifies this behaviour, but I'm darned if I can find the words now.) Notoriously this causes applications to fail if the library they are run against uses different values for the static finals - this used to be a major problem for independent implementations, as Sun didn't publish the values they were using. It's still a snare for the unwary. > In my opinion, the safest place to do constant > inlining is in a class loader, when you know that > which specific implementation you're going to 'link' > to. Method inlining is possible during class loading > as well, but would probably require a good heuristic > to avoid a huge increase in code size. Yes, that's right: the logical place to do this would be in the phase we call "referencing", or maybe a bit later in a verifying/bytecode rewriting phase if one exists. In the latter case one could encode the actual value directly into the instruction, by-passing the constant pool entirely. > I intend to experiment with that in kaffe, but I'm too > busy merging stuff in to do much development at the > moment ;) Know the feeling. ;> It's got me thinking too though - I might at least instrument Wonka to find out what the size distribution of static methods is. If there are a lot of one-liners or empty(!) methods then there may be some low-hanging fruit to be had ... Cheers -- Chris Gray VM Architect, ACUNIA _______________________________________________ Classpath mailing list [EMAIL PROTECTED] http://mail.gnu.org/mailman/listinfo/classpath
