about non-compatible optimization (was: Re: patch to bring java vtables closer to g++ abi conformance)

Tom Tromey tromey@redhat.com
Thu Jan 24 09:03:00 GMT 2002


>>>>> "Tuomas" == Tuomas Leikola <tuomas.leikola@digia.com> writes:

Tuomas> this leads to another issue, is it planned that gcj would
Tuomas> support "closed world" optimizations?

As far as I know nobody is working on it.  I think it would be a
useful addition.

Tuomas> but compiler can "notice" many cases like this, like

Tuomas> Vector a = new Vector();
Tuomas> while (a.size() < 10)
Tuomas> {
Tuomas>     a.add("");
Tuomas> }
Tuomas> the dynamic invocations could be avoided.

Type-based optimizations like this are one thing I hope to get out of
the `ast' (tree-based optimization) work being done.  Another
optimization in this category is removing redundant cast checks.  I've
looked at the ast code a little, but I haven't done any hacking on it
yet :-(

Tom



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