Fix cDAC server GC free region enumeration

[max-charlamb]

Server GC stores free_regions as an inline array within each GC heap. The cDAC model currently treats this field as a pointer, causing the first list's num_free_regions value to be interpreted as an address. This can produce invalid reads such as 0x2b when enumerating server GC free regions.

This changes GCHeapSVR.FreeRegions to use FieldAddress and adds unit coverage for the server GC inline free-region array across all target architectures.

Tests:

• Microsoft.Diagnostics.DataContractReader.Tests: 3,098 passed

Note

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Pull request overview

Fixes server GC free-region enumeration in cDAC by treating GCHeapSVR.FreeRegions as an inline array (address-of field) rather than a pointer value, preventing invalid reads during enumeration.

Changes:

• Switch GCHeapSVR.FreeRegions from [Field] to [FieldAddress] so the contract uses the field’s address.
• Add a unit test covering server heap inline FreeRegions enumeration across standard architectures.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/native/managed/cdac/tests/UnitTests/GCMemoryRegionTests.cs	Adds coverage for enumerating server GC inline free-region arrays via mocked heap layout.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/GC/GCHeapSVR.cs	Updates FreeRegions to use [FieldAddress] so enumeration uses the inline array base address.