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Re: GCJ Native Proposal



Michael Koch wrote:
[...]

You are right, its not always a gain. Tom Tromey told me that he is
aware of one case where the native library is slower then interpreting
the jar.

Doing (c) and fixing JIT runtimes can be good, but it ist a hard work
too. The Kaffe people put much efforts into this. JIT works find on i386
but not at all on powerpc for them. Same mixture for all the other
Debian archs. When Kaffe supports the BC-ABI too this will be huge gain
after all as it is surely be faster then non-JITed bytecode. The idea is
make the code reuseable to other VMs can adopt it too.

We have now 3 possibilitiest:

1) compile all to native
2) compile a selected group of jars to native
3) dont compile to native at all and decide later

Are there any tests done in the past for the gain against jit or
interpretative mode ?

Otherwise I think some testcases would be very good here:

How much gain does it bring for architectures (like i386) - where
already a good jit implementation is available ?

How much gain does it bring for achitectures without a jit
implementation ?

If there is quite a gain for architectures without a jit atm and maybe its also a long way until they have one - it would be worth to provide something in my opinion. Especially as these arches (non i386) are the one which are left alone by the commercial vm implementors.

This way we could also give recommendations to the users later. E.g.
if you are on non-jit arch install the recommended -jbi (or whatever
name will be choosen) packages.

Wolfgang



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