RFR: 8287289: Gather/Scatter with Index Vector [v3]

[Xiaohong Gong]

On Tue, 11 Apr 2023 04:20:08 GMT, Quan Anh Mai <qamai at openjdk.org> wrote:

>> src/hotspot/share/opto/vectornode.hpp line 893:
>> 
>>> 891:     : GatherNode(c, mem, adr, at, vt, indices, scale) {
>>> 892:     assert(indices->bottom_type()->is_vect()->element_basic_type() == T_LONG, "");
>>> 893:   }
>> 
>> We can also get the index type info from the index vector. So is it possible that we use a single node for the gather op, and do the different codegen in ad files based on the index element type? The same to the scatter op.
>
> I'm not sure that all architectures will support 32-bit indices and 64-bit indices similarly. So I think split them make it easier querying for backend support. In x86 a 64-bit index gather support depends on the vector length while 32-bit one depends on the vector length in byte.

OK. Make sense to me. And an alternative way is to adding another matcher method to finish the check. But the change sames also complex. So maybe we could rename the node to `LoadGatherIndexINode/LoadGatherIndexLNode` ?

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PR Review Comment: https://git.openjdk.org/panama-vector/pull/213#discussion_r1162405914