[lworld] RFR: 8373701: [lworld] Revert Use Objects.equals in HashMap and ConcurrentHashmap

[Chen Liang]

On Mon, 15 Dec 2025 19:14:20 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

> Revert the use of Objects.equals to the previous explicit `==` check for identity and conditional call to .equals. The use of Objects.equals (without identity) caused classes with poorly written .equals methods to work incorrectly with HashMap and ConcurrentHashMap.
> 
> This reverts commit c8d4a247861052aa6ed43125bcbe49995326938f.

As discussed with John Rose and others. I guess the goal is to represent == as some sort of C2 macro node, so if an `equals` invocation` tests `==` it can be coalesced with the caller ==.

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Marked as reviewed by liach (Committer).

PR Review: https://git.openjdk.org/valhalla/pull/1800#pullrequestreview-3583422475