Support float16 on ARM CPUs with native float16 support

[FlippFuzz]

From SYSTRAN/faster-whisper#65

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Some CPUs such as ARM Neoverse-N1 (Oracle Cloud free tier) support FP16 computation.
It would be nice to have this feature because there could be up to a 2x speedup in computation speed compared to float32.

I'm just creating the enhancement request and understand that there might not be a focus on this because it only applies to a small subset of CPUs.

[ephemer]

FWIW Apple Silicon CPUs also support FP16 so that adds some more potential consumers here

[nlgtuankiet]

I would love to use faster-whisper instead of whisper.cpp but the lack of FP16 on CPU is kind of the deal breaker for me.
For now, with faster-whisper I have to choose between speed (int8) and accuracy (float32), FP16 is the missing balance point.
Consider that ARM CPUs are very popular nowadays (mobile phone, Apple M series, cloud providers)
I think this is a good idea to consider on fp16 support.
Do you have any thoughts about this @guillaumekln

[bil-ash]

Not just arm and apple silicon, latest intel and AMD CPUs (I am using an AMD one) also support float16. Would be very nice if int8_int16 inference is supported on the CPUs which support float16.