[lworld+fp16] RFR: 8341414: Add support for FP16 conversion routines [v2]

[Bhavana Kilambi]

On Thu, 31 Oct 2024 13:50:40 GMT, Bhavana Kilambi <bkilambi at openjdk.org> wrote:

>> This patch adds intrinsic support for FP16 conversion routines to int/long/double and also the aarch64 backend support. This patch implements both scalar and vector versions for these conversions.
>> 
>> Performance numbers on aarch64 machine with SVE support :
>> 
>> 
>> Benchmark                         (vectorDim)   Gain
>> Float16OpsBenchmark.fp16ToDouble  1024          18.23
>> Float16OpsBenchmark.fp16ToInt     1024          1.93
>> Float16OpsBenchmark.fp16ToLong    1024          3.95
>> 
>> 
>> The Gain column is the ratio between thrpt of this patch and the thrpt with the intrinsics disabled (which generates FP32 arithmetic).
>
> Bhavana Kilambi has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Remove intrinsification of conversion methods in Float16

Hi Jatin, I have added support for float16 to int and long. Apologies for missing the conversion to `short`. Will add that. This patch adds support for fp16 -> double as well. fp16->float is already taken care of.

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PR Comment: https://git.openjdk.org/valhalla/pull/1283#issuecomment-2459867101