RFR: 8264352: AArch64: Optimize vector "not/andNot" for NEON and SVE

Andrew Haley aph at openjdk.java.net
Wed Apr 7 08:34:26 UTC 2021

On Wed, 7 Apr 2021 05:53:46 GMT, Xiaohong Gong <xgong at openjdk.org> wrote:

> Since the vector bitwise `"andNot"` is implemented with `"v1.and(v2.xor(-1))"`, the generated codes with SVE look like:
>   mov z16.b, #-1
>   eor z17.d, z20.d, z16.d
>   and z18.d, z18.d, z17.d
> This could be improved with a single instruction:
>   bic z16.d, z16.d, z18.d
> Similarly, the following optimization for NEON is also needed:
>   not v21.16b, v21.16b
>   and v21.16b, v21.16b, v18.16b  ==>  bic v21.16b, v18.16b, v21.16b
> This patch also adds the following optimization to vector` "not"` for SVE which has already been added for NEON:
>   mov z16.b, #-1
>   eor z17.d, z20.d, z16.d     ==>   not z17.d, p7/m, z20.d
> The performance can improve about `16% ~ 36%` with NEON for the `"AND_NOT"` benchmark [1].
> [1] https://github.com/openjdk/panama-vector/blob/vectorIntrinsics/test/jdk/jdk/incubator/vector/benchmark/src/main/java/benchmark/jdk/incubator/vector/ByteMaxVector.java#L343
> Tested tier1 and jdk:tier3.

Looks OK. Is there any test code for this is mainline?


PR: https://git.openjdk.java.net/jdk/pull/3370

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