Debugging NPE during CanonicalizerPhase

[Thomas Wuerthinger]

Stefan,

Can you upload the IGV graph that is produced by the -G:+DumpOnError flag? You should have "./mx.sh igv" running in parallel and then export the graph as an XML file. Also, what is your stack trace?

Thanks, thomas

On Jul 24, 2013, at 9:16 AM, Stefan Marr <java at stefan-marr.de> wrote:

> 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
>