[vectorIntrinsics] RFR: 8283413: Add C2 mid-end and x86 back-end implementation for bit REVERSE and REVERSE_BYTES operation [v6]

[Jatin Bhateja]

On Thu, 7 Apr 2022 17:57:44 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

>> src/hotspot/share/opto/vectornode.hpp line 1703:
>> 
>>> 1701: 
>>> 1702:   virtual int Opcode() const;
>>> 1703: };
>> 
>> Just a little tip: Can we add Identify for BYTE type, that is ReverseBytesV(x) ->x.
>
> Thanks @theRealELiu ,  its handled on the lines of Revers transformation during final graph reshaping.

FTR, Reverse[bytes] related transforms are special since they cannot be done locally in associated Identity routines since corresponding IR  nodes may be succeeded by blends which are generated after creation of Reverse[bytes] IR, thus GVN related routines for both blend and Reverse[bytes] IR may not be able to handle this transform,  strict pattern match based transform during final graph re-shaping looks promising here.

-------------

PR: https://git.openjdk.java.net/panama-vector/pull/182