Debugging NPE during CanonicalizerPhase

[Stefan Marr]

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


-- 
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