RFR: 8323220: Reassociate loop invariants involved in Cmps and Add/Subs [v5]

[Emanuel Peter]

On Thu, 1 Feb 2024 00:14:47 GMT, Joshua Cao <duke at openjdk.org> wrote:

>> Tests pass, thanks for the updates.
>> I left a few optional comments.
>> 
>> One requiest I would still like to see:
>> You could improve the tests, by returning a value that indicates when the loop was exited, i.e. `return i`. In the future, I intend to verify the return values from test methods, and then we would have additional coverage for free ;)
>> 
>> @caojoshua Update: you can actually already do result verification, with the `@check` method. Can you please add that?
>
> failure is due to mac infra issues and not related to test. @eme64 do the @check's look ok?

@caojoshua sorry, I hope this is not too annoying. I think you are doing good work. We will get there :)

About the add/sub matching fragility: do you know where the other add/sub are coming from? I wonder if there is anything that we could improve in the IR framework to help with that in the future.

I hope that in the future we can drop the `@Check` methods completely, see https://bugs.openjdk.org/browse/JDK-8310533
But that will take a while, since we also plan to refactor the IR framework a little.

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PR Comment: https://git.openjdk.org/jdk/pull/17375#issuecomment-1935392432