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

[Emanuel Peter]

On Mon, 18 Aug 2025 06:13:08 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> src/hotspot/share/opto/loopUnswitch.cpp line 569:
>> 
>>> 567:   // optimizations. That means the slow_loop should still be correct, but
>>> 568:   // a bit slower, as there is no unrolling etc.
>>> 569:   if (!LoopMultiversioningOptimizeSlowLoop) {
>> 
>> Do we really need this in product?  Your benchmarks results shows that we need to optimize slow loop. I can bet nobody will use this flag in real word.
>
> It is a DIAGNOSTIC flag, which allowed me to demonstrate the performance in a JMH benchmark. You asked for that benchmark back when I first introduced multiversioning with https://github.com/openjdk/jdk/pull/22016 . I'm also fine removing the flag completely now. Or just making it develop. What do you think is best?

It is now used in the JMH benchmark, I'd have to remove it there too:
https://github.com/openjdk/jdk/pull/24278/files#diff-93288fabe20d76b9df3fb5601e4d8600a46f438fe4b9c4ef92d702fdffa1c8c9R225-R230

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PR Review Comment: https://git.openjdk.org/jdk/pull/24278#discussion_r2281574475