RFR: 8283091: Support type conversion between different data sizes in SLP [v3]

[Jie Fu]

On Fri, 8 Apr 2022 06:55:27 GMT, Fei Gao <fgao at openjdk.org> wrote:

> costing more than scalar instructions, as we know that there are only two elements for VectorCastD2I on 128-bit NEON machine.

So shall we disable `vcvt2Dto2I` for NEON?

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

PR: https://git.openjdk.java.net/jdk/pull/7806