RFR: 8326139: C2 SuperWord: split packs (match use/def packs, implemented, mutual independence) [v2]

[Emanuel Peter]

On Tue, 27 Feb 2024 17:24:07 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Yes, currently it only seems to handle positive `1`.
>> 
>> Relevant line in `SuperWord::vector_opd`, the only place where the `PopulateIndexNode` is created:
>> `Node* vn = new PopulateIndexNode(iv(), igvn().intcon(1), vt);`
>> 
>> The verification code is at the beginning of `SuperWord::is_vector_use`:
>> `offset_t->get_con() != (jint) i` -> we expect `populate_index->at(i) = (iv + i)`
>> 
>> That is a limitation we can surely remove in a future RFE.
>
> I finally got what this function for :^)  Looks reasonable.

Let me know if you have a better idea to make it more clear then ;)

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PR Review Comment: https://git.openjdk.org/jdk/pull/17848#discussion_r1504674785