RFR: 8365205: C2: Optimize popcount value computation using knownbits [v3]

[Hannes Greule]

On Wed, 10 Sep 2025 14:22:10 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Oh, maybe I missed those "complete logic sweeping tests". Can you please point me to them?
>
> testPopCountElisionInt1 and testPopCountElisionLong1 check for absence of PopCount IR nodes.

I think Or and And nodes aren't updated to make use if KnownBits themselves (that generally makes testing based on KnownBits a bit difficult).

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PR Review Comment: https://git.openjdk.org/jdk/pull/27075#discussion_r2336959670