RFR: 8360192: C2: Make the type of count leading/trailing zero nodes more precise [v10]

[Qizheng Xing]

On Tue, 19 Aug 2025 14:00:37 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Qizheng Xing has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Remove redundant `@require` in IR test
>
> test/hotspot/jtreg/compiler/c2/gvn/TestCountBitsRange.java line 164:
> 
>> 162:         return Long.numberOfTrailingZeros(l) / 8;
>> 163:     }
>> 164: }
> 
> Nice examples! Could you please add a short description to most of them, explaining what you are testing with each? It would help me as a reviewer to see if you cover enough cases.
> 
> I'm also missing some cases where you have non-trivial input ranges. And then verification that the output range is correct.
> 
> You could look at this example:
> https://github.com/openjdk/jdk/pull/25254/files#diff-0e3d89ac8cf0548b69d9bdb0859380bc31de0a772fa7ff211f446a4a5abd4197R220-R248

Added comments for unit tests and random ranges tests like the example.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25928#discussion_r2335744000