RFR: 8319872: AArch64: [vectorapi] Implementation of unsigned (zero extended) casts

[Andrew Haley]

On Wed, 15 Nov 2023 07:48:28 GMT, Eric Liu <eliu at openjdk.org> wrote:

> Vector API defines zero-extend operations [1], which are going to be intrinsified and generated to `VectorUCastNode` by C2. This patch adds backend implementation for `VectorUCastNode` on AArch64.
> 
> The micro benchmark shows significant performance improvement. In my test machine (SVE, 256-bit), the result is shown as below:
> 
> 
> 
>   Benchmark                     Before     After       Units   Gain
>   VectorZeroExtend.byte2Int     3168.251   243012.399  ops/ms  75.70
>   VectorZeroExtend.byte2Long    3212.201   216291.588  ops/ms  66.33
>   VectorZeroExtend.byte2Short   3391.968   182655.365  ops/ms  52.85
>   VectorZeroExtend.int2Long     1012.197    80448.553  ops/ms  78.48
>   VectorZeroExtend.short2Int    1812.471   153416.828  ops/ms  83.65
>   VectorZeroExtend.short2Long   1788.382   129794.814  ops/ms  71.58
> 
> 
> On other Neon systems, we can get similar performance boost as a result of intrinsification success.
> 
> Since `VectorUCastNode` only used in Vector API's zero extension currently, this patch also adds assertion on nodes' definitions to clarify their usages.
> 
> [TEST]
> compiler/vectorapi and jdk/incubator/vector passed on NEON and SVE machines.
> 
> [1] https://github.com/openjdk/jdk/blob/master/src/jdk.incubator.vector/share/classes/jdk/incubator/vector/VectorOperators.java#L726

src/hotspot/cpu/aarch64/aarch64_vector_ad.m4 line 2322:

> 2320:   ins_pipe(pipe_slow);
> 2321: %}
> 2322: 

The following hunk does not seem to be making good use of the macro processor.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16670#discussion_r1394363082