RFR: 8279651: [vectorapi] Implement the missing intrinsics for casting from integrals on x64 [v8]

[Vladimir Ivanov]

On Tue, 18 Jan 2022 15:54:31 GMT, Vladimir Ivanov <vlivanov at openjdk.org> wrote:

>> Good idea, do you know how to properly save the state of a `xmm` register? Currently I can only see using x86_32 approach which does not need to touch the `xmm` registers.
>
> Another option is to pass vector value in register (use vector calling conventions in the stub, e.g. `xmm0`; take a look at `CallLeafVector` used for SVML stubs). It would require fixed location for the vector argument. You can achieve that with additional temporary operand (`rxmm0 tmp`).

BTW I don't fully understand why you need a special case for x86-32. Considering you rely on x87, I assume your intention is to support pre-SSE2 hardware, but vector casts already require AVX. Why can't you share the implementation with x86-64?

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PR: https://git.openjdk.java.net/jdk/pull/7002