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

[Vladimir Kozlov]

On Mon, 18 Aug 2025 06:17:52 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> src/hotspot/share/opto/c2_globals.hpp line 370:
>> 
>>> 368:                                                                             \
>>> 369:   product(bool, UseAutoVectorizationSpeculativeAliasingChecks, true, DIAGNOSTIC, \
>>> 370:           "Use Multiversioning or Predicate to add aliasing runtime checks") \
>> 
>> This flag description implies that it should depend on `LoopMultiversioning` and `UseAutoVectorizationPredicate` flags settings but I did not find such checks.
>
> 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?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24278#discussion_r2282619724