RFR: 8323220: Reassociate loop invariants involved in Cmps and Add/Subs [v6]

[Joshua Cao]

On Wed, 7 Feb 2024 07:43:01 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> @eme64 can you take a look at the updates?
>
> @caojoshua I don't think you have added what I requested. Do you have any test that does the reassociation, and where you verify that the computed values are correct?

OK thanks I think I misread. I now have some correctness tests for tests with and without reassociation. 

We can't add correctness tests for tests with random inputs because we do not know how many iterations there will be. There are two tests with reassociation `equalsVariantSubInvarint(Int|Long)` that have a drastically different graph with the correctness change that messes up the IR matching, so I opted out of changes those as well.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17375#discussion_r1482540647