[vectorIntrinsics] RFR: 8283598: [vectorapi] Add new vector operation for compress bits

[Xiaohong Gong]

On Thu, 24 Mar 2022 06:31:31 GMT, Smita Kamath <svkamath at openjdk.org> wrote:

> Hi,
> 
> I've added support for new vector operations for compressing bits of integral vector types(Byte/Short/Integer/Long).
> The implementation is based on Compress or Generalized Extract mentioned in Hackers Delight by Henry S. Warren, Jr.
> The implementation does the following: given a mask and the number to be compressed, the bits of the number corresponding to the set mask bit are selected and compressed. 
> 
> Currently, this PR addresses only Java changes for compress bits operation. I've also updated the test framework.
> Do review and share feedback.

src/hotspot/share/prims/vectorSupport.cpp line 538:

> 536:         case T_INT:
> 537:         case T_LONG: return Op_CompressBits;
> 538:         default: fatal("COMPRESS_BITS: %s", type2name(bt));

The identity issue "three spaces before `"case"`". Seems the above bitcount and reverse have the same issue. So please fix them together. Thanks!

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PR: https://git.openjdk.java.net/panama-vector/pull/184