RFR: 8277882: New subnode ideal optimization: converting "c0 - (x + c1)" into "(c0 - c1) - x" [v4]

[Dean Long]

On Tue, 30 Nov 2021 22:44:59 GMT, Zang, Zhiqiang <duke at openjdk.java.net> wrote:

>> Suggest two new optimizations that can be done in SubINode::Ideal.
>
> Zang, Zhiqiang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   add ok_to_convert to the condition.

Testing results for 5965a8cf70fec00355bf07315d9a450a24771ed2 look good.

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PR: https://git.openjdk.java.net/jdk/pull/6441