[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/opto/mulnode.hpp line 396:

> 394: class CompressBitsNode : public Node {
> 395: public:
> 396:   CompressBitsNode( Node *in1, Node *in2 ) : Node(0,in1,in2) {}

Style: the spaces are not needed after `"("` and before `")"`. And spaces are needed between the arguments. And `"*"` is better to be next close to the type. So suggest to modify as:
`CompressBitsNode(Node* in1, Node* in2) : Node(0, in1, in2) {}`

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

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