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

[Quan Anh Mai]

On Thu, 22 Jan 2026 12:09:24 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> 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).

`Xbatch` works fine, so I changed to `Xbatch`. Running without any flags can also trigger the failure. I keep both run configurations. What do you think?

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PR Review Comment: https://git.openjdk.org/jdk/pull/29308#discussion_r2716971527