Debugging NPE during CanonicalizerPhase

[Andreas Woess]

Hi Stefan,

Unfortunately, those are the tricky ones to debug. I'll investigate.
What's the simplest test that where this happens?

- andreas

On 07.08.2013 16:07, Stefan Marr wrote:
> Hi Andreas:
>
> On 07 Aug 2013, at 13:26, Andreas Woess <andreas.woess at jku.at> wrote:
>
>> You have this code in ContextualNode:
>>>          FrameSlot blockSelfSlot =
>>> ctx.getFrameDescriptor().findFrameSlot("self");
>>>
>> findFrameSlot will probably never return null here, but the compiler
>> cannot know this and creates one branch where the frameSlot is null and
>> one where it isn't -- in both branches it would call getObject. So a
>> simple workaround would be to explicitly check for a (non-)null result here.
>>
>> In any case, you should avoid findFrameSlot in compiled code and try to
>> resolve frame slots at compile time, if possible. Or, at least
>> specialize the access node after resolving the frame slot. In all
>> likelihood, the frame slot will be the same every time.
> Thanks! That was on the spot.
> I already made sure that I didn't use findFrameSlot in the non-local returns, but I missed this one.
>
> A one-line fix :)
> https://github.com/smarr/TruffleSOM/commit/2bb714220bdca36dc2166bc240ca7dfb957364cb
>
> Now it runs the benchmarks to completion :) nice. Thanks a lot!
>
> I guess, now it is time for me to investigate how to specialize nodes.
>
> A question that might be related to that: I noticed that methods have been repeatedly optimized and then invalidated.
> And by repeatedly I am talking about thousands of times, I actually had to bump up the compilation threshold to make the benchmarks complete in a reasonable amount of time. Any idea what that could be indicating? Typically the benchmarks with such behavior are rather tight loops, recursion, fibonacci etc.
>
> Thanks
> Stefan
>
> Example output:
>
> [truffle] optimized Method at 346ff652                                    |Nodes       4 |Time    46(  10+36  )ms |Nodes   347/ 1135 |CodeSize 4886
> [truffle] invalidated Method at 346ff652                                  |Alive     1ms |Inv# 1101                                     |Replace# 0
> [truffle] optimized Method at 346ff652                                    |Nodes       4 |Time    61(  15+46  )ms |Nodes   347/ 1135 |CodeSize 4886
> [truffle] invalidated Method at 346ff652                                  |Alive     0ms |Inv# 1102                                     |Replace# 0
> [truffle] optimized Method at 346ff652                                    |Nodes       4 |Time    45(  11+35  )ms |Nodes   347/ 1135 |CodeSize 4886
> [truffle] invalidated Method at 346ff652                                  |Alive     0ms |Inv# 1103                                     |Replace# 0
>
>