RFR: 8364202: CDS without G1 gives build error in slowdebug, asserts in fastdebug

[Calvin Cheung]

On Tue, 29 Jul 2025 06:14:46 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> This patch fixes two problems:
> 
> - when building without INCLUDE_CDS_JAVA_HEAP (disabling G1 at configure, or building 32-bit), we get a linker error in slowdebug.
> - when running with CDS, but without INCLUDE_CDS_JAVA_HEAP, we initialize CompressedKlassPointers via the "lenient" route where we allow optimized encoding base choice. This can lead to zero-based encoding, in which case we should not attempt to setup a protection zone at the start of the encoding range.

Looks good.
I did some sanity testing (tiers 1 - 3, and zero build). No failures.

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Marked as reviewed by ccheung (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26523#pullrequestreview-3069192720