JIT: Disallow partial compilation of runtime async functions#125267
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jakobbotsch wants to merge 1 commit intodotnet:mainfrom
Open
JIT: Disallow partial compilation of runtime async functions#125267jakobbotsch wants to merge 1 commit intodotnet:mainfrom
jakobbotsch wants to merge 1 commit intodotnet:mainfrom
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Partial compilation removes the IR of the blocks being partially compiled. That makes the liveness computed by runtime async inaccurate, meaning that we will fail to capture variables needed after the OSR transition. We could make this work by keeping the uses inside `TransformPartialCompilation`, for example adding them as arguments to `CORINFO_HELP_PATCHPOINT_FORCED`. If we ever decide to enable partial compilation by default that seems like a better solution.
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Pull request overview
This PR prevents Tier0 partial compilation from being applied to runtime async methods, because partial compilation can drop IR from deferred blocks and make runtime-async liveness analysis inaccurate across OSR transitions.
Changes:
- Split Tier0 OSR enablement vs partial compilation enablement into separate booleans (
enableOSR,enablePartialCompilation). - Disallow marking partial compilation patchpoints when
compIsAsync()is true.
jakobbotsch
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You could also go back to assuming everything is live? |
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Yes, that would work too. I suppose it is a question of what is best for throughput overall. But it would require some more special casing in the async transformation than the change here. |
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cc @dotnet/jit-contrib PTAL @AndyAyersMS |
AndyAyersMS
approved these changes
Mar 6, 2026
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Partial compilation removes the IR of the blocks being partially compiled. That makes the liveness computed by runtime async inaccurate, meaning that we will fail to capture variables needed after the OSR transition.
We could make this work by keeping the uses inside
TransformPartialCompilation, for example adding them as arguments toCORINFO_HELP_PATCHPOINT_FORCED. If we ever decide to enable partial compilation by default that seems like a better solution.Fix #125247