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Simplify frozen object heap allocation - #135956
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MichalStrehovsky merged 3 commits intoOct 20, 2026
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WASM has no page protection or separate reserve/commit operations, so the Unix mmap(PROT_NONE)/mprotect implementation fails when reflection needs a frozen segment. Use aligned, zeroed native allocations with matching free, and make commit a no-op. Select the WASM partial implementation in NativeAOT CoreLib while leaving the Unix implementation unchanged elsewhere. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: a6f3a617-acae-4f4f-95d3-20b2a0bac43c
MichalStrehovsky
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Tagging subscribers to 'arch-wasm': @lewing, @pavelsavara |
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Tagging subscribers to this area: @agocke, @dotnet/ilc-contrib |
jkotas
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Oct 16, 2026
This was referenced Oct 16, 2026
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Use ordinary zeroed native allocations across platforms and start frozen segments at 4 KB. Remove virtual-memory bookkeeping, platform partials, copied assertion comments, and the unused MProtect interop declaration. Exercise segment growth and compacting GC in the reflection smoke test. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 6dc84b16-c9f8-4272-be81-c459f49f6429
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🟡 Changes recommended
The allocator rewrite changes desktop memory policy beyond the stated WASM-only scope without desktop validation.
1 open issue
What changed in this PR
Enables NativeAOT frozen-object allocation on WASM by replacing platform-specific virtual memory operations with shared zero-initialized native allocations.
Changes:
- Reworks segment allocation and removes reserve/commit helpers.
- Removes obsolete project entries and managed
MProtectinterop. - Adds reflection checks for dynamically created array types across forced garbage collection.
| File | Description |
|---|---|
| src/tests/nativeaot/SmokeTests/Reflection/Reflection.cs | Adds runtime-type identity and rank checks. |
| src/libraries/Common/src/Interop/Unix/System.Native/Interop.MProtect.cs | Removes managed protection interop. |
| src/coreclr/nativeaot/System.Private.CoreLib/src/System.Private.CoreLib.csproj | Removes platform allocator includes. |
| src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/FrozenObjectHeapManager.Windows.cs | Removes Windows virtual-memory helpers. |
| src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/FrozenObjectHeapManager.Unix.cs | Removes Unix virtual-memory helpers. |
| src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/FrozenObjectHeapManager.cs | Uses shared zeroed allocations with smaller initial segments. |
Review effort: Balanced
MichalStrehovsky
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jkotas
reviewed
Oct 19, 2026
Let NativeMemory.AllocZeroed propagate allocation failures instead of retrying with a smaller frozen segment. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: 6dc84b16-c9f8-4272-be81-c459f49f6429
jkotas
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Oct 19, 2026
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/ba-g timeout on wasm |
This was referenced Oct 20, 2026
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The use of this is more rare than on CoreCLR VM. The implementation can be simpler.