RFR: 8347273: C2: VerifyIterativeGVN for Ideal and Identity [v3]

[Emanuel Peter]

On Tue, 10 Jun 2025 08:46:04 GMT, Manuel Hässig <mhaessig at openjdk.org> wrote:

>> Emanuel Peter has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Update src/hotspot/share/opto/phaseX.cpp
>>    
>>    Co-authored-by: Manuel Hässig <manuel at haessig.org>
>>  - review suggestions, and handled a few more edge cases
>
> Thank you for working on this and diligently noting the exceptions. That is quite the todo list you discovered 😅. It is great to see more verification going in.
> 
> I noted some minor things, mostly in the comments. With or without those, this looks good to me.

@mhaessig Thanks for reviewing! Yes this was rather a lot of gruesome work actually 😅 But worth it I think 😊 

I applied you suggestions. And I found some more cases in tier4 and stress testing, so I handled those as well now.

> src/hotspot/share/opto/phaseX.cpp line 1803:
> 
>> 1801:   }
>> 1802:   tty->print_cr("The result after Ideal:");
>> 1803:   i->dump_bfs(1, nullptr, "");
> 
> Perhaps taking the tty lock might be appropriate, due to the amount of printing? Or do we know that nothing else is printing?

good idea!

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PR Comment: https://git.openjdk.org/jdk/pull/22970#issuecomment-2958370829
PR Review Comment: https://git.openjdk.org/jdk/pull/22970#discussion_r2137375811