Change heap dumps to use HEAP2 as the default

[hoyosjs]

This pull request simplifies and unifies the logic for memory region enumeration when generating heap dumps. It makes HEAP2 the default heap dump and deprecates old env vars that work around slow dumps. It assumes LocaderAllocators have all necessary data. This path does a few things better and is higher perf. It enumerates the following:

Enumerates
JitManager -> Code Heaps
SystemDomain -> GlobalLoaderAllocator (was missing before partially).
AppDomain -> LoaderAllocator
Assembly -> LoaderAllocator
Module -> LoaderAllocator
LoaderAllocator -> All Loader Heaps (also collecting collectible ones now).

It skips

• Objects living in the loader alloc: Module hashtables, ClassLoader explicit enumeration, EEClass MethodDescChunks, MethodTable DispatchMap.
• Thread AppDomain, Debugger Module info, Debugger MethodDesc info which have already been enumerated.

[Copilot]

Pull request overview

This PR changes CoreCLR heap-dump memory region enumeration to use the HEAP2 path by default, removing legacy/slow enumeration paths and createdump environment-variable workarounds.

Changes:

• Removes several legacy EnumMemoryRegions sub-enumerations that were skipped for HEAP2 and primarily supported the older heap-dump path.
• Forces heap dump generation through CLRDATA_ENUM_MEM_HEAP2 in DAC enumeration and createdump’s DAC-based region enumeration.
• Simplifies the “custom dump” enumeration worker to a single mini-style path.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/coreclr/vm/threads.cpp	Removes AppDomain enumeration from thread region enumeration for non-HEAP2 legacy paths.
src/coreclr/vm/methodtable.cpp	Drops DispatchMap explicit enumeration for legacy non-HEAP2 dump paths.
src/coreclr/vm/class.cpp	Removes explicit Module + MethodDescChunk enumeration for legacy non-HEAP2 dump paths.
src/coreclr/vm/ceeload.cpp	Removes extensive Module hashtable/type/member explicit enumeration for legacy non-HEAP2 dump paths; keeps HEAP2 loader allocator enumeration.
src/coreclr/vm/assembly.cpp	Removes legacy Assembly sub-enumerations; keeps HEAP2 loader allocator enumeration only.
src/coreclr/debug/ee/functioninfo.cpp	Removes legacy debugger module/methoddesc/sequence-map explicit enumeration for non-HEAP2 paths.
src/coreclr/debug/daccess/enummem.cpp	Makes heap dumps always run via HEAP2; simplifies Custom dump worker and removes HEAP handling in wrapper.
src/coreclr/debug/createdump/crashinfo.cpp	Removes env-var-based opt-out/compat behavior; always uses HEAP2 for DAC-based enumeration.

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[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Comments suppressed due to low confidence (1)

src/coreclr/debug/daccess/enummem.cpp:1951

• EnumMemoryRegionsWrapper() no longer handles CLRDATA_ENUM_MEM_HEAP even though it remains a public flag in clrdata.h. Passing CLRDATA_ENUM_MEM_HEAP will now hit the debug assert and (in retail) effectively do nothing while still returning S_OK. Consider mapping HEAP -> HEAP2 for backward compatibility, or returning a failing HRESULT (e.g., E_INVALIDARG) to avoid silent success.

        else if (flags == CLRDATA_ENUM_MEM_TRIAGE)
        {
            // triage micro-dump
            status = EnumMemoryRegionsWorkerMicroTriage(flags);
        }
        else if (flags == CLRDATA_ENUM_MEM_HEAP2)
        {
            status = EnumMemoryRegionsWorkerHeap(flags);
        }
        else
        {
            _ASSERTE(!"Bad flags passing to EnumMemoryRegionsWrapper!");
        }
    }