[Gllug] One more time...

[Richard Jones]

On Wed, Jun 11, 2003 at 02:24:26AM +0100, Pete Ryland wrote:
> On Wed, Jun 11, 2003 at 01:30:05AM +0100, Nix wrote:
> > Well, again, the latter is a failing of javac, not of the language.
> > Distinguishing between Java-the-language (impoverished, like most Algolic
> > languages), the JVM (a rather nice, if rather Java-specific, virtual
> > machine)
> 
> Hmm.. I have to question that the JVM is nice.  I would have thought that a
> 3AC machine would have been much better than a 0-address one.  Then
> machine-specific optimisation would be easier, amongst other minor benefits
> like slightly smaller code size.  I guess on the other side of the balance
> is the added complexity of the interpreter.

The JVM sucks up huge amounts of memory to perform the simplest tasks,
and doesn't cache the results of JIT compilation so takes many seconds
to start up (important in interactive Java programs like 'ant' - don't
believe what people tell you about interactive performance not being
essential).

> I haven't looked into native-code compilation of Java in about seven years
> (it was my thesis topic), and therefore I don't know how gcj does
> native-code compilation, but IIRC the late binding (that is, for those who
> don't know what I'm talking about, that a method call, for example, is
> referred to *by name* in calling code and only resolved when the call is
> actually made) basically kills any benefit you might get from compiling a
> class natively.

A bloke at Imperial College is working on this. Basically it involves
some very hairy stuff where you inline method calls, but are prepared
to "uninline" them (and consequently recompile large amounts of
dependent code) whenever you load a class into the JVM. Ugh!

Rich.

-- 
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