Re: JIT optimization framework (was: Re: [Sablevm-user] bug report...)

[Andrew P. <apu...@ac...>]

"Etienne M. Gagnon" wrote:

> Have you looked at the "Soot" framework
> (http://www.sable.mcgill.ca/soot/)?  It does already provide more than
> this, including most analyses you need.  It's internal representation is
> "stackless" 3-address codes, with "typed" local variables.  We have
> already a few papers about this.  It might be a good starting point.
> Currently, Soot statically analyses whole applications with no dynamic
> class loading, but you could probably adapt it to dynamic code.

Thanks!

And now I guess I know where the name "SableVM" comes from...

> Assuming SableVM already executes the bytecodes (while you are
> optimizing them on another thread), this should have already been done,
> so you shouldn't care about verification in the JIT.

That's true. 

> As I said in an earlier message, I do not think that JIT compiling every
> method is a good way to go.  Ideally, you want the optimizer to pick
> frequently executed code, then take the time to crunch this as best as
> it can. 

I agree. It is the VM's choice when to invoke the JIT anyway. It is
free to compile information wrt. method invocation and invoke the JIT
only when a particular method meets some selection criteria -- such as
a high invocation count, code length, or advance knowledge of
performance "importance". It's an integration detail, albiet a big
one.


Andrew Purtell
from home -- apu...@ac...