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

[Joshua Cao]

On Fri, 1 Mar 2024 05:41:14 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>>> One more concern I just had: do we have tests for the pre-existing Add/Sub reassociations?
>> 
>> Not that I know of. A bunch of reassociation was added in https://github.com/openjdk/jdk/commit/23ed3a9e91ac57295d274fefdf6c0a322b1e87b7, which does not have any tests.
>> 
>> I ran `make CONF=linux-x86_64-server-fastdebug test TEST=all TEST_VM_OPTS=-XX:-TieredCompilation` on my Linux machine. I have 4 failures in `SctpChannel` and 3 failures in `CAInterop.java`, but they also fail on master branch so they should not be caused by this patch. Hopefully this adds a little more confidence.
>
> @caojoshua 
> 
> I also ran our internal testing and it looks ok (only unrelated failures). But of course that is only on tests that we have, and if the other reassociations are not tested, then that helps little ;)
> 
>> Not that I know of. A bunch of reassociation was added in https://github.com/openjdk/jdk/commit/23ed3a9e91ac57295d274fefdf6c0a322b1e87b7, which does not have any tests.
> 
> Could you please add a result verification test per case of pre-existing reassociation? Otherwise I'm afraid it is hard to be sure you did not break those cases.

@eme64 I added a bunch of tests for add/sub reassociation. I made them IR tests since there are some cases where the IR matching is interesting. I added node matching to each for completeness. But I'd say more importantly they test correctness.

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PR Comment: https://git.openjdk.org/jdk/pull/17375#issuecomment-2011252099