RFR: 8283094: Add Ideal transformation: x + (con - y) -> (x - y) + con

[Zhiqiang Zang]

On Mon, 14 Mar 2022 04:54:48 GMT, Quan Anh Mai <duke at openjdk.java.net> wrote:

> That is what I mean by saying that careless strength reduction restricts our ability to perform more efficient transformations. What I propose is we delay your mentioned transformation after idealisation has settled on the whole graph. Thanks.

Thank you. I was wondering if you mean other stage, for example `Identity` (afaik `Identity` is invoked after `Ideal`), by saying "after idealisation has settled on the whole graph"? I am not sure where I should move transformation.

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PR: https://git.openjdk.java.net/jdk/pull/7795