[vectorIntrinsics] RFR: 8283709: Add x86 back-end implementation for bit BIT_COUNT operation [v3]

[Jatin Bhateja]

On Mon, 28 Mar 2022 02:45:13 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

>> src/hotspot/cpu/x86/c2_MacroAssembler_x86.cpp line 4537:
>> 
>>> 4535:     ShouldNotReachHere();
>>> 4536:   }
>>> 4537:   if (rbt == T_INT) {
>> 
>> So the SLP and the VectorAPI uses the same `PopCountVL` with different basic type?
>
> Is it possible to separate this cast for SLP and always uses "T_LONG' as the basic type for `PopCountVL` ?

We can have type homogeneity for PopCountVL across VectorAPI and SLP once we start auto-vectorizing ConvL2I  operation.

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PR: https://git.openjdk.java.net/panama-vector/pull/185