[kaffe] Bug Report: accessing array doesn't throw NullPointerException under MIPS

Kevin D. Kissell kevink at mips.com
Thu Mar 6 08:34:01 PST 2003

> Correct, the intrp engine works fine (albiet *SO* much slower).
> The test are now passing.
> Kevin, since you seem to implicated as being the MIPS assembly guru, is 
> there any way that I can assist with the JIT3 engine fixed?

Maybe.  See below.

> Since our application is running on an embedded (300 Mhz, 30 MB RAM) 
> system my gut feeling would be that we would get a better mix of 
> performance/memory with JIT.  Is there anything definitive for kaffe?

Even broken, the kaffe JIT on MIPS is good for a factor of *20*
performance on Embedded Caffeinemark (which is admittedly a
pretty broken benchmark that is insanely favorable to JITs). 
I don't know what's "definitive".  I have a little time to look at
the problem just now, so maybe I can advance things.  It's hard
to see what's really going on, but most (but not all) of the JIT
failures are on regression tests that failed similarly on the Intrp
builds up until I fixed the argument passing logic at the native
method invocation interface.  The JIT code which does the same
thing is similar (and similarly convoluted), but my attempts at
finding and fixing the "same" bug were not initially successful.
So I'm rolling up my sleeves, starting from a clean CVS update,
and seeing what I can find.  If you (or anyone else) have any interest 
or experience in figuring out what's wrong from a "top down",
starting from the regression test and identifying the specific failure
mode, that would be really helpful.  Already, you've provided 
a small test case for a new failure mode.  ;o)


            Kevin K.

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