RFR: 8356328: Some C2 IR nodes miss size_of() function [v2]

[kuaiwei]

On Thu, 8 May 2025 12:16:45 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

>> I checked some nodes. `cmp/hash` are not always updated for new fields. It looks "nice to have". I have added `cmp/hash` for “EncodeISOArrayNode/ClearArrayNode/OpaqueMultiversioningNode" .
>
> Thanks for doing that but it's not only nice to have, right? GVN might otherwise incorrectly common two different nodes.

I found `OpaqueNode` can not have `cmp` and `hash`, it will fail some tests. I think these nodes can not be optimized by GVN.

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PR Review Comment: https://git.openjdk.org/jdk/pull/25081#discussion_r2080993730