RFR: 8324890: C2 SuperWord: refactor out VLoop, make unrolling_analysis static, remove init/reset mechanism [v8]

[Emanuel Peter]

On Thu, 8 Feb 2024 18:33:03 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Emanuel Peter has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 18 commits:
>> 
>>  - manual merge
>>  - Merge branch 'master' into JDK-8324890
>>  - add VSharedData class
>>  - manual merge
>>  - timing code from JDK-8325159
>>  - handle AutoVectorizeStatus::TriedAndFailed outside autovectorize
>>  - Merge branch 'master' into JDK-8324890
>>  - _vtrace is moved to VLoop
>>  - comment update
>>  - cosmetics
>>  - ... and 8 more: https://git.openjdk.org/jdk/compare/b02599d2...dcade5f3
>
> src/hotspot/share/opto/vectorization.hpp line 156:
> 
>> 154:   GrowableArray<int>& node_idx_to_loop_body_idx() {
>> 155:     // Since this is a shared resource, we clear before every individual use.
>> 156:     _node_idx_to_loop_body_idx.clear();
> 
> I think it should be explicit `VSharedData::clear()` method called in `auto_vectorize()`. Otherwise much later someone will have hard time to find place where the space is cleared.

@vnkozlov done.

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PR Review Comment: https://git.openjdk.org/jdk/pull/17624#discussion_r1483887728