RFR: 8304144: G1: Remove unnecessary is_survivor check in G1ClearCardTableTask

[Albert Mingkun Yang]

On Tue, 14 Mar 2023 15:02:57 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Simple removing redundant check.
> 
> Test: tier1-6

"dirty" in "dirty_young_block" can be misleading. It's like "annotation" as it essentially calls `g1_mark_as_young`, which ensures writes to young-gen doesn't trigger the barrier slow path (e.g. `G1BarrierSet::write_ref_field_post`).

In other places, "dirty" has a reserved meaning that the heap mem range for a dirty card potentially contains an old-to-young pointer that must be scanned.

It's probably better to rename this method to sth less misleading in another PR.

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PR: https://git.openjdk.org/jdk/pull/13023