[kaffe] debugging JITted methods
robilad at kaffe.org
Mon Mar 15 06:59:02 PST 2004
kaffe at jbbrown9.mailshell.com wrote:
> I am using Kaffe for a research project in school where I am adding a
> bytecode to some .class files. It's a new bytecode and I'm trying to
> make the changes to the JIT to account for the new bytecode, but coming
> across some trouble.
> I started out making changes to the interpreter. Mostly, it involved
> copying/pasting INVOKESTATIC in kaffe.def and adding a couple asm(...)
> statements. But, it turns out I need to use the JIT, which is not so
> straightforward. I've been working on it some and think I have an idea
> of how I need to do things differently, but debugging is going to be
> tough. As a rudimentary way of debugging, I have been trying to find a
> way to dump the JITted method so I could look at that, but haven't been
> able to find a good way to do that.
See the xdebugging support (FAQ.xdebugging) for a way to generate
debugging information in jitted code siutable for gdb.
You can take a look at the emitted code from the jitter by configuring
and building kaffe with --enable-debug and using kaffe -vmdebug JIT to
run your classes.
> I expect implementing the new code could be done really cleanly (and
> quickly) by someone who really understands how the JIT is implemented.
> I'm just having a tough time figuring that out.
See FAQ.jit3 for a nice overview of how jit3 works.
> If you can help me out some, I'd really appreciate it. If I get it all
> figured out, I'd be willing to write up some documentation on how I did
> what I'm working on so if/when other people try to do something similar
> they could suffer a little less than me.
That would be very welcome!
> About my environment:
> My PC is intel/linux
> Kaffe is compiled to alpha/digital unix
> I'm running the JVM on an alpha simulator on the intel machine
> This makes debugging much tougher because if I run gdb I'm debugging the
> simulator, not kaffe. I might be able to run gdb on the simulator, but
> I'd like to avoid trying to set that up unless absolutely necessary. It
> took me long enough to get kaffe running on it.
Out of curiosity: There is an alpha simulator for intel macines? Is it
If you want access to real Alpha hardware, check out HP-Compaq's
TestDrive project. You can sign up for online access to alpha-linux,
alpha-osf (and so on ..) hardware.
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