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Avoid tagged shared dynamic-interface vtable entries on WASM - #135957
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MichalStrehovsky merged 1 commit intoOct 16, 2026
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Emit null sealed-vtable entries for unsupported shared IDynamicInterfaceCastable implementations. WASM function-pointer relocation addends identify funclets and cannot encode the instantiating-thunk flag. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Copilot-Session: a6f3a617-acae-4f4f-95d3-20b2a0bac43c
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Tagging subscribers to 'arch-wasm': @lewing, @pavelsavara |
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jkotas
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Oct 16, 2026
This was referenced Oct 16, 2026
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/ba-g widespread mutex failures; this change is not exercised by CI |
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Summary
Avoid emitting unsupported tagged shared
IDynamicInterfaceCastablemethod pointers in NativeAOT WASM sealed vtables.The instantiating-thunk flag is encoded as a function-pointer relocation addend. WASM function pointers are table indices, and the object writer interprets nonzero function addends as funclet ordinals. The flag therefore becomes a reference to a nonexistent funclet and crashes compilation.
Emit null entries for shared dynamic-interface implementations on WASM, with a TODO marking the unsupported scenario. Other sealed-vtable entries and non-WASM targets are unchanged.
This is deliberately a compile-time bringup fix, not runtime support for shared dynamic-interface dispatch. Real support needs a signature-correct way to supply the generic context; changing the pointer encoding alone is insufficient.
Validation
On the combined local NativeAOT WASI bringup tree, including other unmerged enablement:
.\build.cmd clr.tools -rc Checked -lc Release -os wasi -arch wasmpassed.This branch contains only this cherry-picked commit from
main; it was not built independently. Unsupported shared dynamic-interface dispatch itself was not executed.Note
This PR description was generated by GitHub Copilot.