[vectorIntrinsics] RFR: 8274569: X86 backend related incorrectness issues in legacy store mask patterns

[Sandhya Viswanathan]

On Thu, 30 Sep 2021 19:34:43 GMT, Jatin Bhateja <jbhateja at openjdk.org> wrote:

> - Issue was seen while unit testing changes for masking related optimizations on vectorIntrinsics branch.
> 
> - Following patterns result into incorrect store mask computation, even though contextually store-mask is followed by StoreVector which does takes care of various vector sizes. But C2 does emit VectorStoreMask in IR to populate a byte vector. 
> 
>   - instruct storeMask2B
>   - instruct storeMask4B
>   - instruct storeMask8B
>   - instruct storeMask8B_avx
> 
> - Replicate with immI operand is correctly taking care of shorter vector lengths thus it can be fall back case for following pattern with immediate -1 argument. 
>   - instruct ReplI_M1
>   
> Patch also adds a test case which exhaustively coves load/store vector masks operations for different SPECIES.

Marked as reviewed by sviswanathan (Committer).

The patch looks good to me.

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PR: https://git.openjdk.java.net/panama-vector/pull/139