RFR: JDK-8265259: G1: Fix HeapRegion::block_is_obj for unloading class in full gc

[Stefan Johansson]

On Thu, 15 Apr 2021 12:07:47 GMT, Hamlin Li <mli at openjdk.org> wrote:

> In JDK-8262068, we have introduced an enhancement to skip compacting some heap regions.
> But the objs in these regions might have been dead, and their classes might have been unloaded, at this situation, we need following change to make sure we don't get into trouble when calls HeapRegion::block_is_obj(const HeapWord* p) and subsequent calls e.g. to get obj size.

Browsed the code a bit more, don't we need to change the condition here as well?
https://github.com/openjdk/jdk/blob/838c11fc0ea5f1118bd5a20d1849e67b4941ecff/src/hotspot/share/gc/g1/heapRegion.inline.hpp#L127

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PR: https://git.openjdk.java.net/jdk/pull/3514