RFR: 8327387: G1: Refactor region liveness processing after completion of concurrent marking

[Kalebe Szlachta]

On Tue, 5 Mar 2024 17:23:11 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> The diff is not quite easy to follow. Instead, I'd recommend to read the new code directly, and the entry-point (and the gist) is in `G1OnRegionClosure::do_heap_region`.
> 
> While running BigRamTester, h2, and specjbb2015-fixed, a slight reduction in subphase time (approximately 0.01ms) was observed. However, it's important to note that these subphases are already quite brief in baseline.
> 
> Test: tier1-6

Marked as reviewed by kalebers at github.com (no known OpenJDK username).

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PR Review: https://git.openjdk.org/jdk/pull/18127#pullrequestreview-1918988269