Debugging NPE during CanonicalizerPhase

[Stefan Marr]

Hi Andreas:

On 07 Aug 2013, at 00:58, Andreas Woess <andreas.woess at jku.at> wrote:

> Looks like a frame slot field in one of your nodes was null at compile
> time and read as a constant value. I'll have a look at your code tomorrow.

That could well be.
Are you suggesting that the frame slots should be initialize with a language value?

During execution there shouldn't be any reads of uninitalized values, but with the compilation it might be.

Thanks
Stefan


> 
> We'll add better checks soon.
> 
> - andreas
> 
> On 07.08.2013 00:35, Stefan Marr wrote:
>> Hi Thomas:
>> 
>> On 06 Aug 2013, at 08:56, Thomas Wuerthinger <thomas.wuerthinger at oracle.com> wrote:
>> 
>>> 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?
>> Well, I would like to, but the NPE getting into the way…
>> 
>> Here the two stack traces, once with and once without igv:
>> 
>> http://soft.vub.ac.be/~smarr/downloads/truffle/error-with-igv.txt
>> http://soft.vub.ac.be/~smarr/downloads/truffle/error-without-igv.txt
>> 
>> That's the result with the very latest code from today.
>> Invocation looks like this:
>> ./mx.sh --vm server --debug build debug && ./mx.sh --debug --vm server vm -G:+DumpOnError -Xbootclasspath/a:../som/build/classes som.vm.Universe -cp ../som/Smalltalk ../som/Examples/Benchmarks/Loop.som
>> 
>> So far, I was only able to confirm that the null constant object really appears only in the CanonicalizerPhase.
>> I added checks on the whole graph for everything that happens before the pass.
>> 
>> One question Michael had, and that I investigate is whether there was anything related to TruffleSOM, and I think, the first null constant that was a problem was actually not directly related to my code. But I haven't had the chance to investigate further yet.
>> 
>> Thanks
>> Stefan
>> 
>> PS: TruffleSOM can be build and tested like this:
>> 
>>  $ git clone https://github.com/smarr/TruffleSOM.git som
>>  $ cd som
>>  $ ant test
>> 
> 

-- 
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