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List:       openjdk-graal-dev
Subject:    Debugging NPE during CanonicalizerPhase
From:       Stefan Marr <java () stefan-marr ! de>
Date:       2013-07-24 16:16:44
Message-ID: 291DC66B-3E46-4B44-BBD6-A7B3DEA828D3 () stefan-marr ! de
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Hi:

I am trying to debug an NPE I get while running TruffleSOM on top of Graal.

Would be great if someone could give me a hint, how to debug it.

For a bit of context, I got the latest Graal code checked out and compiled for \
debugging. The invocation looks like this:
  /mx.sh -d --debug --vm server vm -G:+DumpOnError \
-Xbootclasspath/a:../som/build/classes som.vm.Universe -cp ../TruffleSOM/Smalltalk \
../TruffleSOM/Examples/Benchmarks/Loop.som

With a connected Eclipse, I was able to figure out that a FrameGetNode has a value \
for `slot` that is a ConstantNode with the value null (i.e. \
slot.asConstant().isNull() == true).

Now I am a bit stuck, because it looks like the FrameGetNode is never actually \
instantiated with such a ConstantNode object for the slot field, so I assume, it is \
changed somewhere later. However, I have no clue where that might happen.

What also confuses me is that there is no setter for the slot field, and ConstantNode \
as well as Constant look rather immutable to me.

I have the feeling I am missing something rather basic here.
Any hints would be highly appreciated.

Thanks
Stefan


-- 
Stefan Marr
Software Languages Lab
Vrije Universiteit Brussel
Pleinlaan 2 / B-1050 Brussels / Belgium
http://soft.vub.ac.be/~smarr
Phone: +32 2 629 2974
Fax:   +32 2 629 3525


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