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

[Jasmine Karthikeyan]

On Sat, 6 Dec 2025 20:24:28 GMT, Jasmine Karthikeyan <jkarthikeyan at openjdk.org> wrote:

>> @jaskarth Thanks for looking into it!
>> 
>> I would still add the fix, just in case. And I think the test as well, even if it does not reproduce any more.
>> 
>> I was wondering: before the merge, when the test still reproduced:
>> If you removed the `@Warmup(0)` and `CompLevel.C2`, and instead just do `framework.addFlags` with `-Xcomp`, would that reproduce too? If so, you could have a framework run with and one without Xcomp,  the one with Xcomp also should have a compileonly. What do you think?
>> 
>> Or we just push the patch as is, to be sure this is done and integrated. What do you think @chhagedorn ?
>
> Yep, I can replicate the crash on the old commit with `TestFramework.runWithFlags("-Xcomp", "-XX:CompileCommand=compileonly,*TestSubwordTruncation::*");` instead of `@Warmup(0)`. I think this would also be a good option, as it would let you get coverage with Xcomp on the other tests as well.

I've pushed a commit that changes the Warmup(0) to the second test run.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26827#discussion_r2666621951