RFR: 8375653: C2: CmpUNode::sub is not monotonic [v3]

[Christian Hagedorn]

On Thu, 22 Jan 2026 12:04:24 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> Quan Anh Mai has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Test Long::compareUnsigned
>
> test/hotspot/jtreg/compiler/ccp/TestCmpUMonotonicity.java line 29:
> 
>> 27:  * @bug 8375653
>> 28:  * @summary Test that CmpUNode::sub conforms monotonicity
>> 29:  * @run main/othervm -Xcomp -XX:CompileCommand=compileonly,${test.main.class}::test ${test.main.class}
> 
> Was hard to spot but this will not compile anything since we match on `test` instead of `test*`:
> 
> Suggestion:
> 
>  * @run main/othervm -Xcomp -XX:CompileCommand=compileonly,${test.main.class}::test* ${test.main.class}

Can you also add a run without `Xcomp`? Is it required or would it also work with `Xbatch`? The reason I'm asking is because we use 20000 iterations below in the loop in `main()` (maybe we can also run with fewer iterations to trigger the issue).

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PR Review Comment: https://git.openjdk.org/jdk/pull/29308#discussion_r2716641069