RFR: 8367341: C2: apply KnownBits and unsigned bounds to And / Or operations [v3]

[Emanuel Peter]

On Wed, 15 Oct 2025 16:15:05 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> Hi,
>> 
>> This PR improves the implementation of `AndNode/OrNode/XorNode::Value` by taking advantages of the additional information in `TypeInt`. The implementation is pretty straightforward. A clever trick is that by analyzing the negative and positive ranges of a `TypeInt` separately, we have better info for the leading bits. I also implement gtest unit tests to verify the correctness and monotonicity of the inference functions.
>> 
>> Please take a look and leave your reviews, thanks a lot.
>
> Quan Anh Mai has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - remove std::hash
>  - remove unordered_map, add some comments for all_instances_size

Nice, that looks better already. Just looked over the diff, now going to look at the whole patch again.

test/hotspot/gtest/opto/test_rangeinference.cpp line 285:

> 283:       // Quick helper for the tediousness below
> 284:       auto f = [](auto x, auto y) {
> 285:         return x < y ? RBTreeOrdering::LT : RBTreeOrdering::GT;

Suggestion:

        assert(x != y, "we only handle lt and gt cases");
        return x < y ? RBTreeOrdering::LT : RBTreeOrdering::GT;

Would that be correct?

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PR Review: https://git.openjdk.org/jdk/pull/27618#pullrequestreview-3387858662
PR Review Comment: https://git.openjdk.org/jdk/pull/27618#discussion_r2468878934