[vectorIntrinsics+mask] RFR: 8269282: Add masking support for vector gather_load/scatter_store

[Xiaohong Gong]

On Fri, 25 Jun 2021 04:11:53 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

> This patch adds the masking support for masked vector gather load and scatter store, including:
>   1) The Vector API java implementation and hotspot intrinsics changes:
>     - Add masking information to the `loadWithMap/storeWithMap` intrinsics.
>     - Both masked and non-masked gather_load/scatter_store call the same intrinsics. The mask value and class are set to `"null"` for non-masked operations.
>   2) The C2 compiler changes:
>     - Add two new IRs for the masked gather_load/scatter_store. The new masked IR will be generated for masked operation if the platform supports the predicate feature and the backend has implemented it.  Otherwise, the compiler will go back to the default java implementation.

Hi @PaulSandoz , could you please take a look at the JAVA side of this PR? Thanks so much!

@iwanowww @jatin-bhateja , could you please take a look at the compiler side of this PR? Thanks so much!

Thanks,
Xiaohong

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PR: https://git.openjdk.java.net/panama-vector/pull/95