RFR: 8346664: C2: Optimize mask check with constant offset [v17]

[Matthias Ernst]

On Wed, 5 Feb 2025 08:15:42 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> I would leave any details about `addition` to the use of this function, and any discussion how we find the trailing zeros to `AndIL_min_trailing_zeros`. Otherwise it's a little confusing.
>> 
>> It's nice to have examples, and give the reader an intuition of what you are doing in the logic below.
>
> Feel free to tweak the description further ;)

> I would leave any details about addition to the use of this function

I don't think that works well, since the very definition of "what is a zero" is defined in terms of being a neutral element in an addition. So I do think that discussion needs to be here and not in the caller. The caller just reduces the addition.

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PR Review Comment: https://git.openjdk.org/jdk/pull/22856#discussion_r1943676182