RFR: 8324751: C2 SuperWord: Aliasing Analysis runtime check [v11]

[Emanuel Peter]

On Mon, 18 Aug 2025 14:42:28 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> I made the description more precise. The idea is that you can disable the speculative checks with `UseAutoVectorizationSpeculativeAliasingChecks`. If you have the speculative checks enabled, you still need to enable multiversioning and/or the auto vectorization predicate - otherwise that also disables the speculative checks.
>
> I ment, I don't see code for checking flags consistency for flags specified on command line. Consider next combination:
> 
>  % java -XX:+UseAutoVectorizationSpeculativeAliasingChecks -XX:-LoopMultiversioning -XX:-UseAutoVectorizationPredicate Test
> 
> What VM will do?

It would like to add speculative checks, but cannot because neither multiversioning nor predicate is available. Currently, there is no error, nor is there any logic that changes the value of the flag.

Would you like that to be an error?
The downside is that I would have to add special logic in some tests to avoid such errors/crashes, where I now randomly enable and disable these tests.

Or would you like me to check the values of the flags, and then possibly disable `UseAutoVectorizationSpeculativeAliasingChecks` automatically in the VM if neither multiversioning nor the predicate are available?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24278#discussion_r2284155578