RFR: 8366444: Add support for add/mul reduction operations for Float16 [v2]

[Marc Chevalier]

On Thu, 18 Dec 2025 10:12:20 GMT, Bhavana Kilambi <bkilambi at openjdk.org> wrote:

>> src/hotspot/share/opto/vectornode.hpp line 328:
>> 
>>> 326:     ReductionNode(ctrl, in1, in2), _requires_strict_order(requires_strict_order) {}
>>> 327: 
>>> 328:   virtual int Opcode() const;
>> 
>> Build is failing on Mac because of `-Winconsistent-missing-override`: since you specified `override` on `bottom_type` and `ideal_reg`, you need to put `override` everywhere it applies. That means `Opcode` `requires_strict_order`, `hash`, `cmp` and `size_of`. And same in `MulReductionVHFNode`.
>
> Done thanks. Could you please take another look?

Running some tests. I'll take a look.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27526#discussion_r2630429246