git: openjdk/jdk: 8314329: AgeTable: add is_clear() & allocation spec, and relax assert to allow use of 0-index slot

[Y. Srinivas Ramakrishna]

Changeset: df370d72
Author:    Y. Srinivas Ramakrishna <ysr at openjdk.org>
Date:      2024-01-22 19:51:47 +0000
URL:       https://git.openjdk.org/jdk/commit/df370d725e5ae55a05479e8375bf665233ac3e44

8314329: AgeTable: add is_clear() & allocation spec, and relax assert to allow use of 0-index slot

AgeTable changes:
1. add CHeap allocation spec
2. add a non-product const is_clear() method to check if the age table has only zero entries
3. relax the assertion that the 0th index of the age table is never used, to allow use of that slot

Reviewed-by: wkemper, kdnilsen, ayang, shade

! src/hotspot/share/gc/shared/ageTable.cpp
! src/hotspot/share/gc/shared/ageTable.hpp