RFR: 8342095: Add autovectorizer support for subword vector casts [v11]

[Roberto Castañeda Lozano]

On Fri, 2 May 2025 08:57:20 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

> And then it seems that the 32x unrolling leads to some interesting use of registers. I think that the issue is that first all loads are done, and we don't have enough regular registers, so we start pushing to `xmm` registers. And later move them back to regular registers. That creates a very long loop, and that is not very efficient 😬

I don't know the code well but would expect `OptoRegScheduling` to mitigate this issue by producing a more register-pressure aware schedule. Do we know what is preventing that?

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

PR Comment: https://git.openjdk.org/jdk/pull/23413#issuecomment-2850187055