[vectorIntrinsics] RFR: 8285281: [x86] Add C2 mid-end and back-end implementation for COMPRESS_BITS and EXPAND_BITS operations [v3]

[Xiaohong Gong]

On Tue, 26 Apr 2022 10:46:59 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> Summary of changes:
>> - Patch intrinsifies following newly added Java SE APIs
>>    1.  Integer.compress  
>>    2.  Integer.expand
>>    3.  Long.compress
>>    4.  Long.expand
>> - Adds C2 IR nodes and corresponding ideal transformations for new operations.
>> - Inline expansion of  new vector operations COMPRESS_BITS and  EXPAND_BITS are performed using their scalar counterparts and lane insertion/extraction operations.
>> - Performance of JIT sequence generated using above approach vs directly vectorizing scalar algorithm using existing vector APIs is within in +/-%10 range depending on the width of the operation, since X86 offers direct instructions PEXT/PDEP for parallel bit extraction and deposition operations hence performance of scalar loop is always superior to corresponding vector  operations.
>> - Adds an  IR framework based test to validate newly introduced IR transformations.
>> 
>> Kindly review and share your feedback.
>> 
>> Best Regards,
>> Jatin
>
> Jatin Bhateja has updated the pull request incrementally with one additional commit since the last revision:
> 
>   8285281: Review comments resolved.

Please don't forget to add the new added vector ops like `CompressBitsV` and `ExpandBitsV` to function https://github.com/openjdk/jdk/blob/master/src/hotspot/share/adlc/formssel.cpp#L4208. Or the vector type info might be missing by matcher as expected. Thanks!

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PR: https://git.openjdk.java.net/panama-vector/pull/195