[Vm-dev] stack vm questions

Jecel Assumpcao Jr jecel at merlintec.com
Thu May 14 00:05:56 UTC 2009


> [JIT code uses call which pushes PC first]

Ok, so this can't be helped.

> So while one could I don't see that its worth-while.  Even if one did
> keep the arguments and temporaries together one would still have the
> stack contents separate from the arguments and temporaries and
> temporary access bytecodes can still access those so arguably one
> would still have to check the index against the temp count.

Really? I wouldn't expect the compiler to ever generate such bytecodes
and so wasn't too worried if the VM did the wrong thing in this

> In the JIT the flag is a bit in the method reference's LSBs and is set for free
> on frame build.

That sounds like a neat trick. Are the stack formats for the interpreted
stack vm and the jit a little diffeent?

Thanks for the explanations. I haven't figured out how to do this in
hardware in a reasonable way and so might have to go with a different

-- Jecel

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