RFR: 8296157: Rename FileMapInfo::space_at() to region_at()

[Ioi Lam]

On Tue, 1 Nov 2022 21:39:31 GMT, Matias Saavedra Silva <matsaave at openjdk.org> wrote:

> Most of the CDS code refers to a memory blocks inside a CDS file as "regions", represented by the type FileMapRegion. The method FileRegion* space_at() has been renamed to region_at() and all instances of its use have been replaced. Verified with tier 1-4 tests.

Looks good. There's more to change:

- in cds.h, change `_space` to `_regions`, and increment`CURRENT_CDS_ARCHIVE_VERSION` by 1.
- in src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/memory/FileMapInfo.java:
  -  `_space[0]` -> `_regions[0]`, 
  - `spaceField` -> `regions_0Field`
  - `space_0` -> `regions_0`, etc
  - This change is tested by test/hotspot/jtreg/serviceability/sa/ClhsdbCDSCore.java
- You will also see a bunch of C++ compilation errors to tell you what else need to be changed.

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PR: https://git.openjdk.org/jdk/pull/10937