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

[Tobias Hartmann]

On Fri, 11 Oct 2024 23:27:35 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

> When Float.floatToFloat16 is vectorized using a 2-element vector width due to dependencies, we incorrectly generate a 4-element vcvtps2ph with memory as destination storing 8 bytes instead of desired 4 bytes.  This issue is fixed in this PR by limiting the memory version of match rule to 4-element vector and above.
> Also a regression test case is added accordingly.
> 
> Best Regards,
> Sandhya

That looks good to me. @eme64 should have a look as well.

I submitted testing and will report back once it passed.

-------------

Marked as reviewed by thartmann (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/21480#pullrequestreview-2366448884