RFR: 8310190: C2 SuperWord: AlignVector is broken, generates misaligned packs [v58]

[Emanuel Peter]

On Thu, 4 Jan 2024 16:36:19 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> If you really want, then I can not touch `VectorizeDebugOption` at all, i.e. not activate `is_trace_align_vector` with that flag, but instead simply use `TraceSuperWord` (that might be a little verbose though).
>> 
>> I already have the CSR for [JDK-8315361](https://bugs.openjdk.org/browse/JDK-8315361), so that I can remove  `VectorizeDebugOption`. This has 2 effects:
>> 1. remove the product effect of `VectorizeDebugOption`, which is the same effect as enabling `VectorizeOption`.
>> 2. introduce a more general auto-vectorization tracing flag that allows more fine-grained control for debug printing.
>> 
>> My idea here was to simply add the alignment tracing to `VectorizeDebugOption`. But currently one cannot enable that tracing without having the side-effects that also `VectorizeOption` has. Hence, I already now remove that product-side effect.
>> 
>> @vnkozlov what do you think?
>
> I missed that in your long description ;^)
> I agree with your suggestion. The option was indeed strange: mixing prints with affects on code.

Ok, great, I will leave it then 👍

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PR Review Comment: https://git.openjdk.org/jdk/pull/14785#discussion_r1442607787