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

[Emanuel Peter]

On Tue, 10 Jun 2025 09:42:50 GMT, Christian Hagedorn <chagedorn 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
>
> src/hotspot/share/opto/c2_globals.hpp line 686:
> 
>> 684:           "            C: verify Node::Ideal did not miss opportunities"    \
>> 685:           "            D: verify Node::Identity did not miss opportunities" \
>> 686:           "A, B, C, and D in 0=off; 1=on")                                  \
> 
> Why don't you use ABCD? It seems strange/unexpected to reverse the alphabetical order.

It would allow us to extend it further with a most significant bit of `E`, so that the order is `EDCBA`. If I do it in alphabetical order, then I would have to rename them. What do you think?

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PR Review Comment: https://git.openjdk.org/jdk/pull/22970#discussion_r2137655858