RFR: 8351655: Optimize ObjectMonitor::unlink_after_acquire()

[Coleen Phillimore]

On Mon, 17 Mar 2025 13:11:58 GMT, Fredrik Bredberg <fbredberg at openjdk.org> wrote:

> This PR implements an optimization of `ObjectMonitor::unlink_after_acquire()`. If it's possible it only converts the first part (the singly linked part) of the `entry_list` into a doubly linked list and leave the _entry_list_tail pointer untouched. 
> 
> It has passed tier1-tier8 tests.

This looks really good.

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Marked as reviewed by coleenp (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24078#pullrequestreview-2699698452