Revert "Guard unused llvm-libunwind symbols to avoid duplicates on Android"

[MichalStrehovsky]

Resolves #128866.

Reverts #128667

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[Copilot]

Pull request overview

This PR reverts #128667, which had guarded unused llvm-libunwind symbols with a new _LIBUNWIND_NATIVEAOT define to avoid duplicate symbol conflicts on Android (NDK r29). The revert restores the prior approach of using _LIBUNWIND_DISABLE_ZERO_COST_APIS=1 to disable the _Unwind_XXX style APIs.

Changes:

• Revert the _LIBUNWIND_NATIVEAOT guards in the vendored llvm-libunwind sources (libunwind.cpp, Unwind-EHABI.cpp) and drop the corresponding patch entry from llvm-libunwind-version.txt.
• Restore -D_LIBUNWIND_DISABLE_ZERO_COST_APIS=1 (in place of -D_LIBUNWIND_NATIVEAOT=1) in src/coreclr/nativeaot/Runtime/CMakeLists.txt.
• Remove the UnwindHelpers::FindUnwindSections wrapper and call libunwind::LocalAddressSpace::sThisAddressSpace.findUnwindSections directly from UnixNativeCodeManager.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/native/external/llvm-libunwind/src/Unwind-EHABI.cpp	Remove _LIBUNWIND_NATIVEAOT guard around EHABI C++ exception dispatch functions.
src/native/external/llvm-libunwind/src/libunwind.cpp	Remove _LIBUNWIND_NATIVEAOT guard around the public unw_* API block.
src/native/external/llvm-libunwind-version.txt	Drop the reverted commit reference from the applied-patches list.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.h	Remove now-unused FindUnwindSections declaration.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cpp	Remove FindUnwindSections wrapper implementation.
src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cpp	Restore direct call into LocalAddressSpace::sThisAddressSpace.findUnwindSections.
src/coreclr/nativeaot/Runtime/CMakeLists.txt	Replace _LIBUNWIND_NATIVEAOT define with _LIBUNWIND_DISABLE_ZERO_COST_APIS.

[github-actions]

Note

This review was generated by Copilot.

🤖 Copilot Code Review — PR #128883

Holistic Assessment

Motivation: Justified. PR #128667 introduced _LIBUNWIND_NATIVEAOT guards that broke HardwareIntrinsics_General tests on Linux ARM NativeAOT (#128866). A revert is the correct response to a regression in outerloop CI.

Approach: Clean revert restoring the previous _LIBUNWIND_DISABLE_ZERO_COST_APIS approach. The change also correctly reverts the UnwindHelpers::FindUnwindSections wrapper back to direct LocalAddressSpace::sThisAddressSpace.findUnwindSections() usage, and removes the patch reference from llvm-libunwind-version.txt.

Summary: ✅ LGTM. This is a straightforward, complete revert of a commit that caused a regression. All 7 changed files correspond exactly to the inverse of PR #128667. The original Android NDK r29 symbol conflict issue will need to be re-addressed in a follow-up with a different approach that doesn't break ARM unwinding.

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Detailed Findings

✅ Correctness — Revert is complete and accurate

All changes in PR #128667 are fully reverted:

• CMakeLists.txt: _LIBUNWIND_NATIVEAOT → _LIBUNWIND_DISABLE_ZERO_COST_APIS (the original define)
• UnixNativeCodeManager.cpp: Restores direct LocalAddressSpace::sThisAddressSpace.findUnwindSections() call
• UnwindHelpers.cpp/h: Removes the FindUnwindSections wrapper added in Guard unused llvm-libunwind symbols to avoid duplicates on Android #128667
• libunwind.cpp and Unwind-EHABI.cpp: Removes _LIBUNWIND_NATIVEAOT guards
• llvm-libunwind-version.txt: Removes the patch reference

No partial revert or leftover artifacts detected.

✅ Risk Assessment — Low risk

Reverting to a known-good state that was stable before #128667. The only risk is re-exposing the Android NDK r29 symbol conflict, which is a pre-existing issue that needs a different fix approach.

Generated by Code Review for issue #128883 · ● 1.6M · ◷