RFR: 8338126 : C2 SuperWord: VectorCastF2HF / vcvtps2ph produces wrong results for vector length 2 [v2]

[Jatin Bhateja]

On Wed, 16 Oct 2024 01:36:49 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> src/hotspot/cpu/x86/x86.ad line 3679:
>> 
>>> 3677: 
>>> 3678: instruct vconvF2HF_mem_reg(memory mem, vec src) %{
>>> 3679:   predicate(Matcher::vector_length_in_bytes(n->in(3)->in(1)) >= 16);
>> 
>> You can add an eligant prediction check like following instead of accesing bare inputs.
>> 
>> n->as_StoreVector()->memory_size() >= 16.
>
> We have used bare inputs at many places in the ad file in the predicate.

I think its ok to use safe cast if its available atleast for newly added code.

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PR Review Comment: https://git.openjdk.org/jdk/pull/21480#discussion_r1802223433