RFR: 8346664: C2: Optimize mask check with constant offset [v24]

[Emanuel Peter]

On Fri, 14 Feb 2025 07:19:47 GMT, Matthias Ernst <duke at openjdk.org> wrote:

>> Matthias Ernst has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   incorporate @eme64's comment suggestions
>
> I like it, thanks a lot for finishing that up! Incorporated and pushed your version.
> 
> I was _trying_ to avoid a `%` operator and argue with "congruence", e.g. if a and b `equiv` mod m, then a & mask = b & mask, but did not succeed at it :-)

@mernst-github Glad you like it 😊 

I ran testing one more time, since the VM code changed slightly since last time, I think. If @merykitty doesn't disagree we can hopefully integrate after the weekend :)

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PR Comment: https://git.openjdk.org/jdk/pull/22856#issuecomment-2658652671