[release/10.0] Fix missing call to write barrier in static constructors of ref structs#125613
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janvorli wants to merge 1 commit intodotnet:release/10.0from
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[release/10.0] Fix missing call to write barrier in static constructors of ref structs#125613janvorli wants to merge 1 commit intodotnet:release/10.0from
janvorli wants to merge 1 commit intodotnet:release/10.0from
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…rs of ref structs The JIT was incorrectly handling initialization of static fields of ref structs. It was not adding call to JIT_ByRefWriteBarrier when setting these fields even though these statics live in GC heap. This issue was introduced in .NET 10 in dotnet#111733 This change fixes it and adds a regression test that causes fatal error when run with DOTNET_HeapVerify=1.
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Pull request overview
This PR fixes a CoreCLR JIT importer annotation bug where stores to static fields declared on byref-like (ref struct) types could be incorrectly treated as targeting a non-heap location, which can suppress required write barriers and lead to GC heap corruption.
Changes:
- Update importer logic to only mark “field owner is byref-like ⇒ target not on heap” for non-static fields.
- Clarify the comment to reflect the corrected condition (byref-like owner and non-static).
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EgorBo
approved these changes
Mar 16, 2026
This was referenced Mar 16, 2026
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This change fixes it and adds a regression test that causes fatal error when run with DOTNET_HeapVerify=1.
Backport of #125418 to release/10.0
Customer Impact
A customer has reported intermittent crashes in their application after migrating to .NET 10. Analysis has revealed GC heap corruption where a reference field of an object was pointing to a stale address of another object.
The JIT was incorrectly handling initialization of static fields of ref structs. It was not adding call to JIT_ByRefWriteBarrier when setting these fields even though these statics live in GC heap.
Regression
Testing
CI tests, local manual directed test provided by the customer
Risk
Low, the change just adds write barrier call for static fields of ref structs that were missing.