RFR: 8343745: Only update Last Value Assertion Predicates in Loop Unrolling [v2]

[Christian Hagedorn]

On Mon, 11 Nov 2024 06:26:28 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> (Note: This is a dependent PR on https://github.com/openjdk/jdk/pull/21944 which is fully reviewed but I'd prefer to integrate it on Monday and run again some testing over the weekend)
>> 
>> This is a follow-up feature to https://github.com/openjdk/jdk/pull/21944 which updated Loop Unrolling to use a new predicate visitor and enables this patch.
>> 
>> In Loop Unrolling, we only update the stride and not the init value of a loop. Thus, we actually only require to update the Last Value Assertion Predicates because the Init Value Assertion Predicates do not use `OpaqueLoopStride`. So, we also would not be required to kill the old Init Value Initialized Assertion Predicates. This patch implements that improvement.
>> 
>> To make this work, we need to query the associated `AssertionPredicateType` of an Assertion Predicate which is stored in the `If/RangeCheckNode` (I guess it's okay to have this additional node field in product). This was guarded by `NOT_PRODUCT` before. For this patch, I make this information available in product builds and use it to implement this feature.
>> 
>> Thanks,
>> Christian
>
> Christian Hagedorn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase.

Thanks Vladimir for your review!

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PR Comment: https://git.openjdk.org/jdk/pull/21969#issuecomment-2467340652