RFR: 8375536: PPC64: Implement special MachNodes for floating point CMove [v5]

[Richard Reingruber]

On Fri, 30 Jan 2026 14:10:46 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

> That was also wrong, but an additional problem was the wrong handling of NaN: C2 requires unordered to get treated like less

The requirement is to implement `op1 cond op2 ? src1 : src2`. For NaN this means the result has to be `src2` except for `!=`.
And that's it, isn't it?

It might have helped to implement `op1 < op2` as `op2 > op1` using xscmpgtdp. The chosen implementation is also good.

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PR Comment: https://git.openjdk.org/jdk/pull/29281#issuecomment-3824201312