RFR: 8375653: C2: CmpUNode::sub is not monotonic [v4]

[Emanuel Peter]

On Thu, 22 Jan 2026 14:26:18 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Quan Anh Mai has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - Missing patterns
>>  - Add IR tests, fix correctness tests
>
> test/hotspot/jtreg/compiler/c2/gvn/CmpUNodeValueTests.java line 86:
> 
>> 84: 
>> 85:     @Test
>> 86:     @IR(applyIfPlatformOr = {"x64", "true", "aarch64", "true"}, failOn = {IRNode.CMP_U, IRNode.CALL})
> 
> Just as a "control test", can you add a comparison that does not fold away, and so we should find the nodes?
> Otherwise, the risk is that we do `failOn` for the wrong nodes and don't notice.

Below, it may be more helpful to annotate the tests with what you expect the test folds to: `LT`, `GE`, `NE`, ... It would also make it easier to quickly spot if we have covered all cases.

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PR Review Comment: https://git.openjdk.org/jdk/pull/29308#discussion_r2717141764