JIT: Fix async analysis filter dataflow - #132027
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…tion The data flow used for default-value analysis and preserved-value analysis did not properly account for predecessors of filter handlers. Switch to `BlockPredsWithEH` which models all exceptional flow faithfully. Fix dotnet#132015 Fix dotnet#132016 Fix dotnet#132017
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch |
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Pull request overview
This PR updates CoreCLR JIT async default/preserved-value dataflow to account for exceptional predecessors of handler blocks (via BlockPredsWithEH), and adds new async regression tests covering filtered/nested EH cases related to issues #132015/#132016/#132017.
Changes:
- Update
MutationDataFlowCallback::MergeHandlerin async analysis to merge usingBlockPredsWithEHrather than iterating the contiguous try block range. - Clear the
BlockPredsWithEHpredecessor cache before running async analyses to avoid using stale memoized results. - Add three new xUnit-based async regression tests (with minimal per-test csproj files) for the reported scenarios.
Reviewed changes
Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| src/coreclr/jit/asyncanalysis.cpp | Switch handler-merge predecessor enumeration to BlockPredsWithEH for more faithful exceptional-flow modeling. |
| src/coreclr/jit/async.cpp | Clear m_blockToEHPreds cache before async analyses that rely on BlockPredsWithEH. |
| src/tests/async/regression/132015.csproj | Add new regression test project for #132015. |
| src/tests/async/regression/132015.cs | Add regression tests validating value visibility across async suspension with filters/finally. |
| src/tests/async/regression/132016.csproj | Add new regression test project for #132016. |
| src/tests/async/regression/132016.cs | Add regression test for nested catch/filter behavior across async suspension. |
| src/tests/async/regression/132017.csproj | Add new regression test project for #132017. |
| src/tests/async/regression/132017.cs | Add regression test for catch-filter + nested catch starting an un-awaited task. |
jakobbotsch
marked this pull request as ready for review
August 10, 2026 10:34
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Azure Pipelines: Successfully started running 5 pipeline(s). 11 pipeline(s) were filtered out due to trigger conditions. There may be pipelines that require an authorized user to comment /azp run to run. |
jakobbotsch
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Aug 10, 2026
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cc @dotnet/jit-contrib PTAL @AndyAyersMS Diffs, few regressions where the optimization no longer kicks in. |
This was referenced Aug 10, 2026
AndyAyersMS
approved these changes
Aug 10, 2026
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Thanks @jakobbotsch - been waiting for this one for a long time. |
jtschuster
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Aug 11, 2026
The data flow used for default-value analysis and preserved-value analysis did not properly account for predecessors of filter handlers. Switch to `BlockPredsWithEH` which models all exceptional flow faithfully.
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The data flow used for default-value analysis and preserved-value analysis did not properly account for predecessors of filter handlers. Switch to
BlockPredsWithEHwhich models all exceptional flow faithfully.Fix #132015
Fix #132016
Fix #132017