RFR: 8365570: C2 fails assert(false) failed: Unexpected node in SuperWord truncation: CastII [v2]

[Jasmine Karthikeyan]

On Tue, 16 Sep 2025 07:47:50 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> Jasmine Karthikeyan has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Update comment for constraint casts
>
> test/hotspot/jtreg/compiler/vectorization/TestSubwordTruncation.java line 431:
> 
>> 429:     }
>> 430: 
>> 431:     @Test(compLevel = CompLevel.C2)
> 
> Any particular reason you've chosen `C2` here and not let the IR framework handle it? (by default it's `ANY` which will compile at the highest available tier). I'm also wondering if this test would fail if someone ran the test with a build without C2.

Thanks for the comment! I used `CompLevel.C2` here to simulate an -Xcomp environment, since unfortunately I couldn't replicate the crash without it with the IR framework. I'll do some investigation to find a way to ensure that it won't fail without C2.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26827#discussion_r2366609927