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[cDAC] Fix ARM unwind implementation - #132183
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Co-authored-by: Copilot <[email protected]> Copilot-Session: 11b73ad8-c726-42c3-bc38-a8360c68b4de
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August 11, 2026 23:32
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Pull request overview
This PR fixes ARM (32-bit) unwind handling in cDAC’s ARMUnwinder so that compact unwind epilog processing restores the caller’s return address correctly, and adds a focused unit test to prevent regressions.
Changes:
- Adjust ARM compact unwind epilog register-mask handling so
Ret==0is treated as poppingPC(and therefore correctly restores the caller context). - Fix
ComputeScopeSizeiteration to avoid reading past the end of the unwind-code stream when searching for end markers. - Add a unit test that reproduces the compact-epilog scenario and asserts restored registers/PC/SP and unwind flags.
Show a summary per file
| File | Description |
|---|---|
| src/native/managed/cdac/tests/UnitTests/StackWalkTests.cs | Adds a regression unit test covering ARM compact unwind epilog restoring caller context. |
| src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/Context/ARM/ARMUnwinder.cs | Fixes compact epilog LR/PC mask handling for Ret==0 and makes unwind-scope size computation safe at buffer boundaries. |
Review details
- Files reviewed: 2/2 changed files
- Comments generated: 0
- Review effort level: Lite
hoyosjs
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Aug 11, 2026
hoyosjs
approved these changes
Aug 11, 2026
max-charlamb
approved these changes
Aug 11, 2026
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Found this auditing the unwind code for discrepancies.