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Guard unused llvm-libunwind symbols to avoid duplicates on Android - #128667

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sbomer:libunwind-ifdef
May 29, 2026
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Guard unused llvm-libunwind symbols to avoid duplicates on Android#128667
jkotas merged 2 commits into
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sbomer:libunwind-ifdef

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NativeAOT uses llvm-libunwind's internal C++ classes directly
(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)
and does not call the public unw_* C API. These symbols conflict with
platform libunwind on Android NDK r29.

Add a _LIBUNWIND_NATIVEAOT define that guards out the public API
symbols NativeAOT does not use:

  • libunwind.cpp: all unw_* functions, unw_local_addr_space, and
    the LocalAddressSpace::sThisAddressSpace singleton
  • AddressSpace.hpp: sThisAddressSpace static member declaration
  • Unwind-EHABI.cpp: the C++ exception dispatch functions are also
    guarded because they depend on the now-guarded unw_* functions
    and would cause undefined symbol errors on ARM32

Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()
accessor instead of the now-guarded sThisAddressSpace singleton. This
delegates to the existing file-local LocalAddressSpace instance in
UnwindHelpers.cpp

Fixes#121172

CopilotAI review requested due to automatic review settings May 27, 2026 21:31
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Pull request overview

This PR updates the NativeAOT build of the vendored llvm-libunwind to avoid duplicate symbol conflicts (notably on Android NDK r29) by compiling out libunwind’s public unw_* entrypoints and related exception-dispatch code that NativeAOT doesn’t use, and by routing NativeAOT’s unwind-section discovery through a runtime-owned helper instead of libunwind’s LocalAddressSpace::sThisAddressSpace singleton.

Changes:

  • Add _LIBUNWIND_NATIVEAOT and use it to guard out unw_* APIs (and the LocalAddressSpace::sThisAddressSpace singleton) in libunwind.cpp, plus dependent EHABI exception-dispatch exports in Unwind-EHABI.cpp.
  • Introduce UnwindHelpers::FindUnwindSections() and switch UnixNativeCodeManager to use it (avoiding the now-guarded sThisAddressSpace).
  • Record the patch application in llvm-libunwind-version.txt and enable the new define in the NativeAOT runtime CMake configuration.
Show a summary per file
FileDescription
src/native/external/llvm-libunwind/src/Unwind-EHABI.cppGuards EHABI exception-dispatch exports when _LIBUNWIND_NATIVEAOT is set to avoid references to removed __unw_* APIs.
src/native/external/llvm-libunwind/src/libunwind.cppGuards the public unw_* API surface and the LocalAddressSpace::sThisAddressSpace singleton under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind/src/AddressSpace.hppGuards the LocalAddressSpace::sThisAddressSpace static member declaration under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind-version.txtNotes the applied commit associated with this local patch.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.hDeclares the new UnwindHelpers::FindUnwindSections accessor.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cppImplements FindUnwindSections by delegating to the existing file-scope _addressSpace.
src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cppReplaces use of LocalAddressSpace::sThisAddressSpace.findUnwindSections with UnwindHelpers::FindUnwindSections.
src/coreclr/nativeaot/Runtime/CMakeLists.txtDefines _LIBUNWIND_NATIVEAOT=1 for Unix NativeAOT builds to enable the guarding behavior.

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  • Files reviewed: 8/8 changed files
  • Comments generated: 0

@am11

am11 commented May 27, 2026

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If it's a negative if !defined(_LIBUNWIND_NATIVEAOT) check everywhere, we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.

jkotas
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Comment threadsrc/native/external/llvm-libunwind/src/AddressSpace.hpp Outdated
Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
@jkotas

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we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.

Deleting the code creates more conflicts during updates. We won't be able to upstream the deletion either. I think ifdefing is better.

jkotas
jkotas reviewed May 27, 2026
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Comment threadsrc/native/external/llvm-libunwind-version.txt Outdated
This was referenced May 28, 2026
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Comment threadsrc/native/external/llvm-libunwind/src/Unwind-EHABI.cpp Outdated
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Comment threadsrc/coreclr/nativeaot/Runtime/CMakeLists.txt Outdated
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sbomerand others added 2 commits May 28, 2026 16:55
@sbomer@jkotas
Guard unused llvm-libunwind symbols to avoid duplicates on Android
fde4a5b
NativeAOT uses llvm-libunwind's internal C++ classes directly
(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)
and does not call the public unw_* C API. These symbols conflict with
platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API
symbols NativeAOT does not use:
- libunwind.cpp: wrap the entire file (except debug logging) in
#if !defined(_LIBUNWIND_NATIVEAOT) as a purely additive patch,
making it resilient to upstream llvm-libunwind updates
- Unwind-EHABI.cpp: the C++ exception dispatch functions are also
guarded because they depend on the now-guarded unw_* functions
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()
accessor instead of the now-guarded sThisAddressSpace singleton. This
delegates to the existing file-local LocalAddressSpace instance in
UnwindHelpers.cpp.
Co-authored-by: Jan Kotas <jkotas@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sbomer
Update llvm-libunwind-version.txt
1004d9f
Reference fde4a5b (Guard unused llvm-libunwind symbols).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@build-analysisbuild-analysisBot mentioned this pull request May 29, 2026
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@sbomer

sbomer commented May 29, 2026

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@jkotas can you please help merge this without squashing?

@jkotas
jkotas merged commit ad724f5 into dotnet:mainMay 29, 2026
164 of 171 checks passed
@sbomer
sbomer deleted the libunwind-ifdef branch May 29, 2026 16:58
@dotnet-maestrodotnet-maestroBot mentioned this pull request May 30, 2026
Merged
@dotnet-milestone-botdotnet-milestone-botBot added this to the 11.0-preview6 milestone May 30, 2026
@MichalStrehovskyMichalStrehovsky mentioned this pull request Jun 1, 2026
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CopilotAI mentioned this pull request Jun 1, 2026
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CopilotAI added a commit that referenced this pull request Jun 1, 2026
@MichalStrehovsky
Fix ARM32 SIGSEGV: narrow _LIBUNWIND_NATIVEAOT guard in Unwind-EHABI.cpp
5697904
Split the single #if !defined(_LIBUNWIND_NATIVEAOT) guard into two blocks
so that _Unwind_VRS_Get, _Unwind_VRS_Get_Internal, _Unwind_VRS_Set,
_Unwind_VRS_Pop, and ValueAsBitPattern are compiled into the NativeAOT
build. These helpers are called by _Unwind_VRS_Interpret which is the
ARM32 EHABI managed-frame unwinding path in NativeAOT.
PR #128667 accidentally included them inside the guard, causing the
linker to resolve them against libgcc_s.so.1 instead of the in-tree
implementations that understand the NativeAOT ArmUnwindCursor shim,
resulting in SIGSEGV during ARM32 stack unwinding.
The genuinely-unused C++ exception dispatch functions (__aeabi_unwind_cpp_pr*,
unwind_phase1/2, _Unwind_RaiseException, _Unwind_ForcedUnwind, etc.) that
depend on __unw_step and other libunwind.cpp public API remain guarded.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
CopilotAI added a commit that referenced this pull request Jun 1, 2026
@MichalStrehovsky
Fix ARM32 NativeAOT SIGSEGV: keep VRS helpers and __unw_*_reg outside…
1cd1620
… _LIBUNWIND_NATIVEAOT guard
PR #128667 accidentally excluded _Unwind_VRS_Get/Set/Pop (and their
__unw_get/set_reg/__unw_save_vfp_as_X dependencies) from the NativeAOT
build while leaving _Unwind_VRS_Interpret (their caller) in place.
The linker resolved the exported VRS symbols from libgcc_s.so.1 which
treats ArmUnwindCursor* as a real libgcc context → SIGSEGV on ARM32.
Unwind-EHABI.cpp: Split single NATIVEAOT guard into two blocks so
ValueAsBitPattern and _Unwind_VRS_Set/Get_Internal/Get/Pop sit between
the two guards (always compiled).
libunwind.cpp: Split single NATIVEAOT guard into smaller inner guards
keeping __unw_get_reg, __unw_set_reg, __unw_get_fpreg, __unw_set_fpreg,
__unw_save_vfp_as_X unconditional so they are compiled for NativeAOT.
The singleton, __unw_init_local, __unw_step, __unw_resume, DWARF/FDE
functions, and Apple dynamic sections remain behind the guard.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
@MichalStrehovsky

MichalStrehovsky commented Jun 1, 2026

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This broke uwinding on arm32. The failure mode is a rather mysterious sigsegv, but pulling down a binary from a failed test run and running nm -D seems to indicate we're linking dynamically against some of GCC's libunwind (@GCC_3.5):

007ca06c D DotNetRuntimeDebugHeader@@V1.0
w _ITM_deregisterTMCloneTable
w _ITM_registerTMCloneTable
U _Unwind_VRS_Get@GCC_3.5
U _Unwind_VRS_Pop@GCC_3.5
U _Unwind_VRS_Set@GCC_3.5
U __aeabi_unwind_cpp_pr0@GCC_3.5
U __aeabi_unwind_cpp_pr1@GCC_3.5
U __aeabi_unwind_cpp_pr2@GCC_3.5
U __clock_gettime64@GLIBC_2.34
U __clock_nanosleep_time64@GLIBC_2.34
U __cxa_atexit@GLIBC_2.4
w __cxa_finalize@GLIBC_2.4
U __errno_location@GLIBC_2.4
U __fcntl_time64@GLIBC_2.34
U __fstat64_time64@GLIBC_2.34
U __getdelim@GLIBC_2.4
... redacted for brevity

Copilot is trying to do something at #128830.

@tannergoodingtannergooding mentioned this pull request Jun 1, 2026
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@MichalStrehovskyMichalStrehovsky mentioned this pull request Jun 2, 2026
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MichalStrehovsky added a commit that referenced this pull request Jun 2, 2026
@MichalStrehovsky
Revert "Guard unused llvm-libunwind symbols to avoid duplicates on An…
c7d8935
…droid" (#128883)
Resolves#128866.
Reverts #128667
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Status: Done

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[NAOT][android] Application linking breaks with NDK r29 because of duplicated libunwind symbols

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function addCopyButtons() {
document.querySelectorAll('pre code').forEach(function(codeBlock) {
if (codeBlock.parentElement.hasAttribute('data-copy-added')) return;
codeBlock.parentElement.setAttribute('data-copy-added', 'true');
var btn = document.createElement('button');
btn.textContent = 'Copy';
btn.style.cssText = 'position:absolute;top:4px;right:4px;padding:2px 8px;font-size:11px;background:#4ecdc4;border:none;border-radius:4px;color:#1a1a2e;cursor:pointer;opacity:0.7;transition:opacity 0.2s;';
btn.onmouseover = function() { this.style.opacity = '1'; };
btn.onmouseout = function() { this.style.opacity = '0.7'; };
btn.onclick = function() {
navigator.clipboard.writeText(codeBlock.textContent).then(function() {
btn.textContent = 'Copied!';
setTimeout(function() { btn.textContent = 'Copy'; }, 1500);
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codeBlock.parentElement.style.position = 'relative';
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var observer = new MutationObserver(addCopyButtons);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
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try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '
Guard unused llvm-libunwind symbols to avoid duplicates on Android by sbomer · Pull Request #128667 · dotnet/runtime · GitHub
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Guard unused llvm-libunwind symbols to avoid duplicates on Android - #128667
Merged
jkotas merged 2 commits into
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sbomer:libunwind-ifdef
May 29, 2026
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Guard unused llvm-libunwind symbols to avoid duplicates on Android#128667
jkotas merged 2 commits into
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sbomer:libunwind-ifdef
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@sbomersbomer
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May 27, 2026•

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NativeAOT uses llvm-libunwind's internal C++ classes directly

(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)

and does not call the public unw_* C API. These symbols conflict with

platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API

symbols NativeAOT does not use:
  • libunwind.cpp: all unw_* functions, unw_local_addr_space, and
    
the LocalAddressSpace::sThisAddressSpace singleton
  • AddressSpace.hpp: sThisAddressSpace static member declaration
  • Unwind-EHABI.cpp: the C++ exception dispatch functions are also
    
guarded because they depend on the now-guarded unw_* functions
    
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()

accessor instead of the now-guarded sThisAddressSpace singleton. This

delegates to the existing file-local LocalAddressSpace instance in

UnwindHelpers.cpp
Fixes#121172
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Pull request overview
This PR updates the NativeAOT build of the vendored llvm-libunwind to avoid duplicate symbol conflicts (notably on Android NDK r29) by compiling out libunwind’s public unw_* entrypoints and related exception-dispatch code that NativeAOT doesn’t use, and by routing NativeAOT’s unwind-section discovery through a runtime-owned helper instead of libunwind’s LocalAddressSpace::sThisAddressSpace singleton.
Changes:
  • Add _LIBUNWIND_NATIVEAOT and use it to guard out unw_* APIs (and the LocalAddressSpace::sThisAddressSpace singleton) in libunwind.cpp, plus dependent EHABI exception-dispatch exports in Unwind-EHABI.cpp.
  • Introduce UnwindHelpers::FindUnwindSections() and switch UnixNativeCodeManager to use it (avoiding the now-guarded sThisAddressSpace).
  • Record the patch application in llvm-libunwind-version.txt and enable the new define in the NativeAOT runtime CMake configuration.
Show a summary per file
FileDescription
src/native/external/llvm-libunwind/src/Unwind-EHABI.cppGuards EHABI exception-dispatch exports when _LIBUNWIND_NATIVEAOT is set to avoid references to removed __unw_* APIs.
src/native/external/llvm-libunwind/src/libunwind.cppGuards the public unw_* API surface and the LocalAddressSpace::sThisAddressSpace singleton under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind/src/AddressSpace.hppGuards the LocalAddressSpace::sThisAddressSpace static member declaration under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind-version.txtNotes the applied commit associated with this local patch.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.hDeclares the new UnwindHelpers::FindUnwindSections accessor.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cppImplements FindUnwindSections by delegating to the existing file-scope _addressSpace.
src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cppReplaces use of LocalAddressSpace::sThisAddressSpace.findUnwindSections with UnwindHelpers::FindUnwindSections.
src/coreclr/nativeaot/Runtime/CMakeLists.txtDefines _LIBUNWIND_NATIVEAOT=1 for Unix NativeAOT builds to enable the guarding behavior.
Copilot's findings
  • Files reviewed: 8/8 changed files
  • Comments generated: 0
@am11
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May 27, 2026

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If it's a negative if !defined(_LIBUNWIND_NATIVEAOT) check everywhere, we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
jkotas
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May 27, 2026
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Comment threadsrc/native/external/llvm-libunwind/src/AddressSpace.hpp
Outdated

Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
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we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
Deleting the code creates more conflicts during updates. We won't be able to upstream the deletion either. I think ifdefing is better.
jkotas
jkotas
reviewed
May 27, 2026
View reviewed changes
Comment threadsrc/native/external/llvm-libunwind-version.txt
Outdated


This was referenced May 28, 2026

Open


Open


This was referenced May 28, 2026

Open


Open

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Comment threadsrc/native/external/llvm-libunwind/src/Unwind-EHABI.cpp
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Comment threadsrc/coreclr/nativeaot/Runtime/CMakeLists.txt
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Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.
sbomerand others
added 2 commits
May 28, 2026 16:55
@sbomer@jkotas
Guard unused llvm-libunwind symbols to avoid duplicates on Android
fde4a5b
NativeAOT uses llvm-libunwind's internal C++ classes directly
(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)
and does not call the public unw_* C API. These symbols conflict with
platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API
symbols NativeAOT does not use:
- libunwind.cpp: wrap the entire file (except debug logging) in
#if !defined(_LIBUNWIND_NATIVEAOT) as a purely additive patch,
making it resilient to upstream llvm-libunwind updates
- Unwind-EHABI.cpp: the C++ exception dispatch functions are also
guarded because they depend on the now-guarded unw_* functions
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()
accessor instead of the now-guarded sThisAddressSpace singleton. This
delegates to the existing file-local LocalAddressSpace instance in
UnwindHelpers.cpp.
Co-authored-by: Jan Kotas <jkotas@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sbomer
Update llvm-libunwind-version.txt
1004d9f
Reference fde4a5b (Guard unused llvm-libunwind symbols).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@jkotas can you please help merge this without squashing?
@jkotas
jkotas
merged commit ad724f5
into
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164 of 171 checks passed

@sbomer
sbomer
deleted the

libunwind-ifdef

branch
May 29, 2026 16:58
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Jun 1, 2026
@MichalStrehovsky
Fix ARM32 SIGSEGV: narrow _LIBUNWIND_NATIVEAOT guard in Unwind-EHABI.cpp
5697904
Split the single #if !defined(_LIBUNWIND_NATIVEAOT) guard into two blocks
so that _Unwind_VRS_Get, _Unwind_VRS_Get_Internal, _Unwind_VRS_Set,
_Unwind_VRS_Pop, and ValueAsBitPattern are compiled into the NativeAOT
build. These helpers are called by _Unwind_VRS_Interpret which is the
ARM32 EHABI managed-frame unwinding path in NativeAOT.
PR #128667 accidentally included them inside the guard, causing the
linker to resolve them against libgcc_s.so.1 instead of the in-tree
implementations that understand the NativeAOT ArmUnwindCursor shim,
resulting in SIGSEGV during ARM32 stack unwinding.
The genuinely-unused C++ exception dispatch functions (__aeabi_unwind_cpp_pr*,
unwind_phase1/2, _Unwind_RaiseException, _Unwind_ForcedUnwind, etc.) that
depend on __unw_step and other libunwind.cpp public API remain guarded.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
CopilotAI
added a commit
that referenced
this pull request
Jun 1, 2026
@MichalStrehovsky
Fix ARM32 NativeAOT SIGSEGV: keep VRS helpers and __unw_*_reg outside…
1cd1620
… _LIBUNWIND_NATIVEAOT guard
PR #128667 accidentally excluded _Unwind_VRS_Get/Set/Pop (and their
__unw_get/set_reg/__unw_save_vfp_as_X dependencies) from the NativeAOT
build while leaving _Unwind_VRS_Interpret (their caller) in place.
The linker resolved the exported VRS symbols from libgcc_s.so.1 which
treats ArmUnwindCursor* as a real libgcc context → SIGSEGV on ARM32.
Unwind-EHABI.cpp: Split single NATIVEAOT guard into two blocks so
ValueAsBitPattern and _Unwind_VRS_Set/Get_Internal/Get/Pop sit between
the two guards (always compiled).
libunwind.cpp: Split single NATIVEAOT guard into smaller inner guards
keeping __unw_get_reg, __unw_set_reg, __unw_get_fpreg, __unw_set_fpreg,
__unw_save_vfp_as_X unconditional so they are compiled for NativeAOT.
The singleton, __unw_init_local, __unw_step, __unw_resume, DWARF/FDE
functions, and Apple dynamic sections remain behind the guard.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
@MichalStrehovsky
MichalStrehovsky
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Jun 1, 2026

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This broke uwinding on arm32. The failure mode is a rather mysterious sigsegv, but pulling down a binary from a failed test run and running nm -D seems to indicate we're linking dynamically against some of GCC's libunwind (@GCC_3.5):
007ca06c D DotNetRuntimeDebugHeader@@V1.0
w _ITM_deregisterTMCloneTable
w _ITM_registerTMCloneTable
U _Unwind_VRS_Get@GCC_3.5
U _Unwind_VRS_Pop@GCC_3.5
U _Unwind_VRS_Set@GCC_3.5
U __aeabi_unwind_cpp_pr0@GCC_3.5
U __aeabi_unwind_cpp_pr1@GCC_3.5
U __aeabi_unwind_cpp_pr2@GCC_3.5
U __clock_gettime64@GLIBC_2.34
U __clock_nanosleep_time64@GLIBC_2.34
U __cxa_atexit@GLIBC_2.4
w __cxa_finalize@GLIBC_2.4
U __errno_location@GLIBC_2.4
U __fcntl_time64@GLIBC_2.34
U __fstat64_time64@GLIBC_2.34
U __getdelim@GLIBC_2.4
... redacted for brevity

Copilot is trying to do something at #128830.
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Revert "Guard unused llvm-libunwind symbols to avoid duplicates on An…
c7d8935
…droid" (#128883)
Resolves#128866.
Reverts #128667
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[NAOT][android] Application linking breaks with NDK r29 because of duplicated libunwind symbols


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Guard unused llvm-libunwind symbols to avoid duplicates on Android by sbomer · Pull Request #128667 · dotnet/runtime · GitHub
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Guard unused llvm-libunwind symbols to avoid duplicates on Android - #128667
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sbomer:libunwind-ifdef
May 29, 2026
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Guard unused llvm-libunwind symbols to avoid duplicates on Android#128667
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sbomer:libunwind-ifdef
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NativeAOT uses llvm-libunwind's internal C++ classes directly

(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)

and does not call the public unw_* C API. These symbols conflict with

platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API

symbols NativeAOT does not use:
  • libunwind.cpp: all unw_* functions, unw_local_addr_space, and
    
the LocalAddressSpace::sThisAddressSpace singleton
  • AddressSpace.hpp: sThisAddressSpace static member declaration
  • Unwind-EHABI.cpp: the C++ exception dispatch functions are also
    
guarded because they depend on the now-guarded unw_* functions
    
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()

accessor instead of the now-guarded sThisAddressSpace singleton. This

delegates to the existing file-local LocalAddressSpace instance in

UnwindHelpers.cpp
Fixes#121172
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Pull request overview
This PR updates the NativeAOT build of the vendored llvm-libunwind to avoid duplicate symbol conflicts (notably on Android NDK r29) by compiling out libunwind’s public unw_* entrypoints and related exception-dispatch code that NativeAOT doesn’t use, and by routing NativeAOT’s unwind-section discovery through a runtime-owned helper instead of libunwind’s LocalAddressSpace::sThisAddressSpace singleton.
Changes:
  • Add _LIBUNWIND_NATIVEAOT and use it to guard out unw_* APIs (and the LocalAddressSpace::sThisAddressSpace singleton) in libunwind.cpp, plus dependent EHABI exception-dispatch exports in Unwind-EHABI.cpp.
  • Introduce UnwindHelpers::FindUnwindSections() and switch UnixNativeCodeManager to use it (avoiding the now-guarded sThisAddressSpace).
  • Record the patch application in llvm-libunwind-version.txt and enable the new define in the NativeAOT runtime CMake configuration.
Show a summary per file
FileDescription
src/native/external/llvm-libunwind/src/Unwind-EHABI.cppGuards EHABI exception-dispatch exports when _LIBUNWIND_NATIVEAOT is set to avoid references to removed __unw_* APIs.
src/native/external/llvm-libunwind/src/libunwind.cppGuards the public unw_* API surface and the LocalAddressSpace::sThisAddressSpace singleton under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind/src/AddressSpace.hppGuards the LocalAddressSpace::sThisAddressSpace static member declaration under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind-version.txtNotes the applied commit associated with this local patch.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.hDeclares the new UnwindHelpers::FindUnwindSections accessor.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cppImplements FindUnwindSections by delegating to the existing file-scope _addressSpace.
src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cppReplaces use of LocalAddressSpace::sThisAddressSpace.findUnwindSections with UnwindHelpers::FindUnwindSections.
src/coreclr/nativeaot/Runtime/CMakeLists.txtDefines _LIBUNWIND_NATIVEAOT=1 for Unix NativeAOT builds to enable the guarding behavior.
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  • Comments generated: 0
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If it's a negative if !defined(_LIBUNWIND_NATIVEAOT) check everywhere, we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
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Comment threadsrc/native/external/llvm-libunwind/src/AddressSpace.hpp
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Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
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we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
Deleting the code creates more conflicts during updates. We won't be able to upstream the deletion either. I think ifdefing is better.
jkotas
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Comment threadsrc/native/external/llvm-libunwind-version.txt
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This was referenced May 28, 2026

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sbomerand others
added 2 commits
May 28, 2026 16:55
@sbomer@jkotas
Guard unused llvm-libunwind symbols to avoid duplicates on Android
fde4a5b
NativeAOT uses llvm-libunwind's internal C++ classes directly
(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)
and does not call the public unw_* C API. These symbols conflict with
platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API
symbols NativeAOT does not use:
- libunwind.cpp: wrap the entire file (except debug logging) in
#if !defined(_LIBUNWIND_NATIVEAOT) as a purely additive patch,
making it resilient to upstream llvm-libunwind updates
- Unwind-EHABI.cpp: the C++ exception dispatch functions are also
guarded because they depend on the now-guarded unw_* functions
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()
accessor instead of the now-guarded sThisAddressSpace singleton. This
delegates to the existing file-local LocalAddressSpace instance in
UnwindHelpers.cpp.
Co-authored-by: Jan Kotas <jkotas@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sbomer
Update llvm-libunwind-version.txt
1004d9f
Reference fde4a5b (Guard unused llvm-libunwind symbols).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@jkotas can you please help merge this without squashing?
@jkotas
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deleted the

libunwind-ifdef

branch
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@MichalStrehovsky
Fix ARM32 SIGSEGV: narrow _LIBUNWIND_NATIVEAOT guard in Unwind-EHABI.cpp
5697904
Split the single #if !defined(_LIBUNWIND_NATIVEAOT) guard into two blocks
so that _Unwind_VRS_Get, _Unwind_VRS_Get_Internal, _Unwind_VRS_Set,
_Unwind_VRS_Pop, and ValueAsBitPattern are compiled into the NativeAOT
build. These helpers are called by _Unwind_VRS_Interpret which is the
ARM32 EHABI managed-frame unwinding path in NativeAOT.
PR #128667 accidentally included them inside the guard, causing the
linker to resolve them against libgcc_s.so.1 instead of the in-tree
implementations that understand the NativeAOT ArmUnwindCursor shim,
resulting in SIGSEGV during ARM32 stack unwinding.
The genuinely-unused C++ exception dispatch functions (__aeabi_unwind_cpp_pr*,
unwind_phase1/2, _Unwind_RaiseException, _Unwind_ForcedUnwind, etc.) that
depend on __unw_step and other libunwind.cpp public API remain guarded.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
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Fix ARM32 NativeAOT SIGSEGV: keep VRS helpers and __unw_*_reg outside…
1cd1620
… _LIBUNWIND_NATIVEAOT guard
PR #128667 accidentally excluded _Unwind_VRS_Get/Set/Pop (and their
__unw_get/set_reg/__unw_save_vfp_as_X dependencies) from the NativeAOT
build while leaving _Unwind_VRS_Interpret (their caller) in place.
The linker resolved the exported VRS symbols from libgcc_s.so.1 which
treats ArmUnwindCursor* as a real libgcc context → SIGSEGV on ARM32.
Unwind-EHABI.cpp: Split single NATIVEAOT guard into two blocks so
ValueAsBitPattern and _Unwind_VRS_Set/Get_Internal/Get/Pop sit between
the two guards (always compiled).
libunwind.cpp: Split single NATIVEAOT guard into smaller inner guards
keeping __unw_get_reg, __unw_set_reg, __unw_get_fpreg, __unw_set_fpreg,
__unw_save_vfp_as_X unconditional so they are compiled for NativeAOT.
The singleton, __unw_init_local, __unw_step, __unw_resume, DWARF/FDE
functions, and Apple dynamic sections remain behind the guard.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
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This broke uwinding on arm32. The failure mode is a rather mysterious sigsegv, but pulling down a binary from a failed test run and running nm -D seems to indicate we're linking dynamically against some of GCC's libunwind (@GCC_3.5):
007ca06c D DotNetRuntimeDebugHeader@@V1.0
w _ITM_deregisterTMCloneTable
w _ITM_registerTMCloneTable
U _Unwind_VRS_Get@GCC_3.5
U _Unwind_VRS_Pop@GCC_3.5
U _Unwind_VRS_Set@GCC_3.5
U __aeabi_unwind_cpp_pr0@GCC_3.5
U __aeabi_unwind_cpp_pr1@GCC_3.5
U __aeabi_unwind_cpp_pr2@GCC_3.5
U __clock_gettime64@GLIBC_2.34
U __clock_nanosleep_time64@GLIBC_2.34
U __cxa_atexit@GLIBC_2.4
w __cxa_finalize@GLIBC_2.4
U __errno_location@GLIBC_2.4
U __fcntl_time64@GLIBC_2.34
U __fstat64_time64@GLIBC_2.34
U __getdelim@GLIBC_2.4
... redacted for brevity

Copilot is trying to do something at #128830.
@tannergoodingtannergooding
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@MichalStrehovsky
Revert "Guard unused llvm-libunwind symbols to avoid duplicates on An…
c7d8935
…droid" (#128883)
Resolves#128866.
Reverts #128667
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[NAOT][android] Application linking breaks with NDK r29 because of duplicated libunwind symbols


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Guard unused llvm-libunwind symbols to avoid duplicates on Android by sbomer · Pull Request #128667 · dotnet/runtime · GitHub
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Guard unused llvm-libunwind symbols to avoid duplicates on Android - #128667
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May 29, 2026
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Guard unused llvm-libunwind symbols to avoid duplicates on Android#128667
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NativeAOT uses llvm-libunwind's internal C++ classes directly

(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)

and does not call the public unw_* C API. These symbols conflict with

platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API

symbols NativeAOT does not use:
  • libunwind.cpp: all unw_* functions, unw_local_addr_space, and
    
the LocalAddressSpace::sThisAddressSpace singleton
  • AddressSpace.hpp: sThisAddressSpace static member declaration
  • Unwind-EHABI.cpp: the C++ exception dispatch functions are also
    
guarded because they depend on the now-guarded unw_* functions
    
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()

accessor instead of the now-guarded sThisAddressSpace singleton. This

delegates to the existing file-local LocalAddressSpace instance in

UnwindHelpers.cpp
Fixes#121172
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Pull request overview
This PR updates the NativeAOT build of the vendored llvm-libunwind to avoid duplicate symbol conflicts (notably on Android NDK r29) by compiling out libunwind’s public unw_* entrypoints and related exception-dispatch code that NativeAOT doesn’t use, and by routing NativeAOT’s unwind-section discovery through a runtime-owned helper instead of libunwind’s LocalAddressSpace::sThisAddressSpace singleton.
Changes:
  • Add _LIBUNWIND_NATIVEAOT and use it to guard out unw_* APIs (and the LocalAddressSpace::sThisAddressSpace singleton) in libunwind.cpp, plus dependent EHABI exception-dispatch exports in Unwind-EHABI.cpp.
  • Introduce UnwindHelpers::FindUnwindSections() and switch UnixNativeCodeManager to use it (avoiding the now-guarded sThisAddressSpace).
  • Record the patch application in llvm-libunwind-version.txt and enable the new define in the NativeAOT runtime CMake configuration.
Show a summary per file
FileDescription
src/native/external/llvm-libunwind/src/Unwind-EHABI.cppGuards EHABI exception-dispatch exports when _LIBUNWIND_NATIVEAOT is set to avoid references to removed __unw_* APIs.
src/native/external/llvm-libunwind/src/libunwind.cppGuards the public unw_* API surface and the LocalAddressSpace::sThisAddressSpace singleton under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind/src/AddressSpace.hppGuards the LocalAddressSpace::sThisAddressSpace static member declaration under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind-version.txtNotes the applied commit associated with this local patch.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.hDeclares the new UnwindHelpers::FindUnwindSections accessor.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cppImplements FindUnwindSections by delegating to the existing file-scope _addressSpace.
src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cppReplaces use of LocalAddressSpace::sThisAddressSpace.findUnwindSections with UnwindHelpers::FindUnwindSections.
src/coreclr/nativeaot/Runtime/CMakeLists.txtDefines _LIBUNWIND_NATIVEAOT=1 for Unix NativeAOT builds to enable the guarding behavior.
Copilot's findings
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  • Comments generated: 0
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If it's a negative if !defined(_LIBUNWIND_NATIVEAOT) check everywhere, we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
jkotas
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Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
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we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
Deleting the code creates more conflicts during updates. We won't be able to upstream the deletion either. I think ifdefing is better.
jkotas
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sbomerand others
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Guard unused llvm-libunwind symbols to avoid duplicates on Android
fde4a5b
NativeAOT uses llvm-libunwind's internal C++ classes directly
(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)
and does not call the public unw_* C API. These symbols conflict with
platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API
symbols NativeAOT does not use:
- libunwind.cpp: wrap the entire file (except debug logging) in
#if !defined(_LIBUNWIND_NATIVEAOT) as a purely additive patch,
making it resilient to upstream llvm-libunwind updates
- Unwind-EHABI.cpp: the C++ exception dispatch functions are also
guarded because they depend on the now-guarded unw_* functions
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()
accessor instead of the now-guarded sThisAddressSpace singleton. This
delegates to the existing file-local LocalAddressSpace instance in
UnwindHelpers.cpp.
Co-authored-by: Jan Kotas <jkotas@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sbomer
Update llvm-libunwind-version.txt
1004d9f
Reference fde4a5b (Guard unused llvm-libunwind symbols).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@jkotas can you please help merge this without squashing?
@jkotas
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merged commit ad724f5
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dotnet:mainMay 29, 2026

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@sbomer
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deleted the

libunwind-ifdef

branch
May 29, 2026 16:58
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added this to the 11.0-preview6 milestone
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@MichalStrehovskyMichalStrehovsky
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@MichalStrehovsky
Fix ARM32 SIGSEGV: narrow _LIBUNWIND_NATIVEAOT guard in Unwind-EHABI.cpp
5697904
Split the single #if !defined(_LIBUNWIND_NATIVEAOT) guard into two blocks
so that _Unwind_VRS_Get, _Unwind_VRS_Get_Internal, _Unwind_VRS_Set,
_Unwind_VRS_Pop, and ValueAsBitPattern are compiled into the NativeAOT
build. These helpers are called by _Unwind_VRS_Interpret which is the
ARM32 EHABI managed-frame unwinding path in NativeAOT.
PR #128667 accidentally included them inside the guard, causing the
linker to resolve them against libgcc_s.so.1 instead of the in-tree
implementations that understand the NativeAOT ArmUnwindCursor shim,
resulting in SIGSEGV during ARM32 stack unwinding.
The genuinely-unused C++ exception dispatch functions (__aeabi_unwind_cpp_pr*,
unwind_phase1/2, _Unwind_RaiseException, _Unwind_ForcedUnwind, etc.) that
depend on __unw_step and other libunwind.cpp public API remain guarded.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
CopilotAI
added a commit
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@MichalStrehovsky
Fix ARM32 NativeAOT SIGSEGV: keep VRS helpers and __unw_*_reg outside…
1cd1620
… _LIBUNWIND_NATIVEAOT guard
PR #128667 accidentally excluded _Unwind_VRS_Get/Set/Pop (and their
__unw_get/set_reg/__unw_save_vfp_as_X dependencies) from the NativeAOT
build while leaving _Unwind_VRS_Interpret (their caller) in place.
The linker resolved the exported VRS symbols from libgcc_s.so.1 which
treats ArmUnwindCursor* as a real libgcc context → SIGSEGV on ARM32.
Unwind-EHABI.cpp: Split single NATIVEAOT guard into two blocks so
ValueAsBitPattern and _Unwind_VRS_Set/Get_Internal/Get/Pop sit between
the two guards (always compiled).
libunwind.cpp: Split single NATIVEAOT guard into smaller inner guards
keeping __unw_get_reg, __unw_set_reg, __unw_get_fpreg, __unw_set_fpreg,
__unw_save_vfp_as_X unconditional so they are compiled for NativeAOT.
The singleton, __unw_init_local, __unw_step, __unw_resume, DWARF/FDE
functions, and Apple dynamic sections remain behind the guard.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
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This broke uwinding on arm32. The failure mode is a rather mysterious sigsegv, but pulling down a binary from a failed test run and running nm -D seems to indicate we're linking dynamically against some of GCC's libunwind (@GCC_3.5):
007ca06c D DotNetRuntimeDebugHeader@@V1.0
w _ITM_deregisterTMCloneTable
w _ITM_registerTMCloneTable
U _Unwind_VRS_Get@GCC_3.5
U _Unwind_VRS_Pop@GCC_3.5
U _Unwind_VRS_Set@GCC_3.5
U __aeabi_unwind_cpp_pr0@GCC_3.5
U __aeabi_unwind_cpp_pr1@GCC_3.5
U __aeabi_unwind_cpp_pr2@GCC_3.5
U __clock_gettime64@GLIBC_2.34
U __clock_nanosleep_time64@GLIBC_2.34
U __cxa_atexit@GLIBC_2.4
w __cxa_finalize@GLIBC_2.4
U __errno_location@GLIBC_2.4
U __fcntl_time64@GLIBC_2.34
U __fstat64_time64@GLIBC_2.34
U __getdelim@GLIBC_2.4
... redacted for brevity

Copilot is trying to do something at #128830.
@tannergoodingtannergooding
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@MichalStrehovsky
Revert "Guard unused llvm-libunwind symbols to avoid duplicates on An…
c7d8935
…droid" (#128883)
Resolves#128866.
Reverts #128667
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[NAOT][android] Application linking breaks with NDK r29 because of duplicated libunwind symbols


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@sbomer@am11@jkotas@MichalStrehovsky

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Guard unused llvm-libunwind symbols to avoid duplicates on Android by sbomer · Pull Request #128667 · dotnet/runtime · GitHub
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Guard unused llvm-libunwind symbols to avoid duplicates on Android - #128667
Merged
jkotas merged 2 commits into
dotnet:mainfrom 
sbomer:libunwind-ifdef
May 29, 2026
Merged
Guard unused llvm-libunwind symbols to avoid duplicates on Android#128667
jkotas merged 2 commits into
dotnet:mainfrom 
sbomer:libunwind-ifdef
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NativeAOT uses llvm-libunwind's internal C++ classes directly

(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)

and does not call the public unw_* C API. These symbols conflict with

platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API

symbols NativeAOT does not use:
  • libunwind.cpp: all unw_* functions, unw_local_addr_space, and
    
the LocalAddressSpace::sThisAddressSpace singleton
  • AddressSpace.hpp: sThisAddressSpace static member declaration
  • Unwind-EHABI.cpp: the C++ exception dispatch functions are also
    
guarded because they depend on the now-guarded unw_* functions
    
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()

accessor instead of the now-guarded sThisAddressSpace singleton. This

delegates to the existing file-local LocalAddressSpace instance in

UnwindHelpers.cpp
Fixes#121172
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Pull request overview
This PR updates the NativeAOT build of the vendored llvm-libunwind to avoid duplicate symbol conflicts (notably on Android NDK r29) by compiling out libunwind’s public unw_* entrypoints and related exception-dispatch code that NativeAOT doesn’t use, and by routing NativeAOT’s unwind-section discovery through a runtime-owned helper instead of libunwind’s LocalAddressSpace::sThisAddressSpace singleton.
Changes:
  • Add _LIBUNWIND_NATIVEAOT and use it to guard out unw_* APIs (and the LocalAddressSpace::sThisAddressSpace singleton) in libunwind.cpp, plus dependent EHABI exception-dispatch exports in Unwind-EHABI.cpp.
  • Introduce UnwindHelpers::FindUnwindSections() and switch UnixNativeCodeManager to use it (avoiding the now-guarded sThisAddressSpace).
  • Record the patch application in llvm-libunwind-version.txt and enable the new define in the NativeAOT runtime CMake configuration.
Show a summary per file
FileDescription
src/native/external/llvm-libunwind/src/Unwind-EHABI.cppGuards EHABI exception-dispatch exports when _LIBUNWIND_NATIVEAOT is set to avoid references to removed __unw_* APIs.
src/native/external/llvm-libunwind/src/libunwind.cppGuards the public unw_* API surface and the LocalAddressSpace::sThisAddressSpace singleton under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind/src/AddressSpace.hppGuards the LocalAddressSpace::sThisAddressSpace static member declaration under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind-version.txtNotes the applied commit associated with this local patch.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.hDeclares the new UnwindHelpers::FindUnwindSections accessor.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cppImplements FindUnwindSections by delegating to the existing file-scope _addressSpace.
src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cppReplaces use of LocalAddressSpace::sThisAddressSpace.findUnwindSections with UnwindHelpers::FindUnwindSections.
src/coreclr/nativeaot/Runtime/CMakeLists.txtDefines _LIBUNWIND_NATIVEAOT=1 for Unix NativeAOT builds to enable the guarding behavior.
Copilot's findings
  • Files reviewed: 8/8 changed files
  • Comments generated: 0
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If it's a negative if !defined(_LIBUNWIND_NATIVEAOT) check everywhere, we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
jkotas
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Comment threadsrc/native/external/llvm-libunwind/src/AddressSpace.hpp
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Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
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we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
Deleting the code creates more conflicts during updates. We won't be able to upstream the deletion either. I think ifdefing is better.
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Comment threadsrc/native/external/llvm-libunwind-version.txt
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This was referenced May 28, 2026

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Comment threadsrc/native/external/llvm-libunwind/src/Unwind-EHABI.cpp
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Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.
sbomerand others
added 2 commits
May 28, 2026 16:55
@sbomer@jkotas
Guard unused llvm-libunwind symbols to avoid duplicates on Android
fde4a5b
NativeAOT uses llvm-libunwind's internal C++ classes directly
(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)
and does not call the public unw_* C API. These symbols conflict with
platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API
symbols NativeAOT does not use:
- libunwind.cpp: wrap the entire file (except debug logging) in
#if !defined(_LIBUNWIND_NATIVEAOT) as a purely additive patch,
making it resilient to upstream llvm-libunwind updates
- Unwind-EHABI.cpp: the C++ exception dispatch functions are also
guarded because they depend on the now-guarded unw_* functions
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()
accessor instead of the now-guarded sThisAddressSpace singleton. This
delegates to the existing file-local LocalAddressSpace instance in
UnwindHelpers.cpp.
Co-authored-by: Jan Kotas <jkotas@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sbomer
Update llvm-libunwind-version.txt
1004d9f
Reference fde4a5b (Guard unused llvm-libunwind symbols).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@jkotas can you please help merge this without squashing?
@jkotas
jkotas
merged commit ad724f5
into
dotnet:mainMay 29, 2026

164 of 171 checks passed

@sbomer
sbomer
deleted the

libunwind-ifdef

branch
May 29, 2026 16:58
@dotnet-maestrodotnet-maestroBot
mentioned this pull request
May 30, 2026
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added this to the 11.0-preview6 milestone
May 30, 2026
@MichalStrehovskyMichalStrehovsky
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@MichalStrehovsky
Fix ARM32 SIGSEGV: narrow _LIBUNWIND_NATIVEAOT guard in Unwind-EHABI.cpp
5697904
Split the single #if !defined(_LIBUNWIND_NATIVEAOT) guard into two blocks
so that _Unwind_VRS_Get, _Unwind_VRS_Get_Internal, _Unwind_VRS_Set,
_Unwind_VRS_Pop, and ValueAsBitPattern are compiled into the NativeAOT
build. These helpers are called by _Unwind_VRS_Interpret which is the
ARM32 EHABI managed-frame unwinding path in NativeAOT.
PR #128667 accidentally included them inside the guard, causing the
linker to resolve them against libgcc_s.so.1 instead of the in-tree
implementations that understand the NativeAOT ArmUnwindCursor shim,
resulting in SIGSEGV during ARM32 stack unwinding.
The genuinely-unused C++ exception dispatch functions (__aeabi_unwind_cpp_pr*,
unwind_phase1/2, _Unwind_RaiseException, _Unwind_ForcedUnwind, etc.) that
depend on __unw_step and other libunwind.cpp public API remain guarded.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
CopilotAI
added a commit
that referenced
this pull request
Jun 1, 2026
@MichalStrehovsky
Fix ARM32 NativeAOT SIGSEGV: keep VRS helpers and __unw_*_reg outside…
1cd1620
… _LIBUNWIND_NATIVEAOT guard
PR #128667 accidentally excluded _Unwind_VRS_Get/Set/Pop (and their
__unw_get/set_reg/__unw_save_vfp_as_X dependencies) from the NativeAOT
build while leaving _Unwind_VRS_Interpret (their caller) in place.
The linker resolved the exported VRS symbols from libgcc_s.so.1 which
treats ArmUnwindCursor* as a real libgcc context → SIGSEGV on ARM32.
Unwind-EHABI.cpp: Split single NATIVEAOT guard into two blocks so
ValueAsBitPattern and _Unwind_VRS_Set/Get_Internal/Get/Pop sit between
the two guards (always compiled).
libunwind.cpp: Split single NATIVEAOT guard into smaller inner guards
keeping __unw_get_reg, __unw_set_reg, __unw_get_fpreg, __unw_set_fpreg,
__unw_save_vfp_as_X unconditional so they are compiled for NativeAOT.
The singleton, __unw_init_local, __unw_step, __unw_resume, DWARF/FDE
functions, and Apple dynamic sections remain behind the guard.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
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This broke uwinding on arm32. The failure mode is a rather mysterious sigsegv, but pulling down a binary from a failed test run and running nm -D seems to indicate we're linking dynamically against some of GCC's libunwind (@GCC_3.5):
007ca06c D DotNetRuntimeDebugHeader@@V1.0
w _ITM_deregisterTMCloneTable
w _ITM_registerTMCloneTable
U _Unwind_VRS_Get@GCC_3.5
U _Unwind_VRS_Pop@GCC_3.5
U _Unwind_VRS_Set@GCC_3.5
U __aeabi_unwind_cpp_pr0@GCC_3.5
U __aeabi_unwind_cpp_pr1@GCC_3.5
U __aeabi_unwind_cpp_pr2@GCC_3.5
U __clock_gettime64@GLIBC_2.34
U __clock_nanosleep_time64@GLIBC_2.34
U __cxa_atexit@GLIBC_2.4
w __cxa_finalize@GLIBC_2.4
U __errno_location@GLIBC_2.4
U __fcntl_time64@GLIBC_2.34
U __fstat64_time64@GLIBC_2.34
U __getdelim@GLIBC_2.4
... redacted for brevity

Copilot is trying to do something at #128830.
@tannergoodingtannergooding
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Jun 2, 2026
@MichalStrehovsky
Revert "Guard unused llvm-libunwind symbols to avoid duplicates on An…
c7d8935
…droid" (#128883)
Resolves#128866.
Reverts #128667
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Status: Done


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Successfully merging this pull request may close these issues.

[NAOT][android] Application linking breaks with NDK r29 because of duplicated libunwind symbols


5 participants

@sbomer@am11@jkotas@MichalStrehovsky

, 'i');
if (__m === '*' || __re.test(location.href)) {
// Auto-enable theater mode on YouTube
(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
}
}
// Try immediately
tryTheater();
// Try after navigation (SPA)
var lastUrl = location.href;
setInterval(function() {
if (location.href !== lastUrl) {
lastUrl = location.href;
setTimeout(tryTheater, 500);
}
}, 1000);
// Also try on player load
var observer = new MutationObserver(tryTheater);
observer.observe(document.body, { childList: true, subtree: true });
})();
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Guard unused llvm-libunwind symbols to avoid duplicates on Android by sbomer · Pull Request #128667 · dotnet/runtime · GitHub
Skip to content
Guard unused llvm-libunwind symbols to avoid duplicates on Android - #128667
Merged
jkotas merged 2 commits into
dotnet:mainfrom 
sbomer:libunwind-ifdef
May 29, 2026
Merged
Guard unused llvm-libunwind symbols to avoid duplicates on Android#128667
jkotas merged 2 commits into
dotnet:mainfrom 
sbomer:libunwind-ifdef
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@sbomer
@sbomersbomer
commented
May 27, 2026•

edited

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NativeAOT uses llvm-libunwind's internal C++ classes directly

(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)

and does not call the public unw_* C API. These symbols conflict with

platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API

symbols NativeAOT does not use:
  • libunwind.cpp: all unw_* functions, unw_local_addr_space, and
    
the LocalAddressSpace::sThisAddressSpace singleton
  • AddressSpace.hpp: sThisAddressSpace static member declaration
  • Unwind-EHABI.cpp: the C++ exception dispatch functions are also
    
guarded because they depend on the now-guarded unw_* functions
    
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()

accessor instead of the now-guarded sThisAddressSpace singleton. This

delegates to the existing file-local LocalAddressSpace instance in

UnwindHelpers.cpp
Fixes#121172
CopilotAI
review requested due to automatic review settings
May 27, 2026 21:31
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Pull request overview
This PR updates the NativeAOT build of the vendored llvm-libunwind to avoid duplicate symbol conflicts (notably on Android NDK r29) by compiling out libunwind’s public unw_* entrypoints and related exception-dispatch code that NativeAOT doesn’t use, and by routing NativeAOT’s unwind-section discovery through a runtime-owned helper instead of libunwind’s LocalAddressSpace::sThisAddressSpace singleton.
Changes:
  • Add _LIBUNWIND_NATIVEAOT and use it to guard out unw_* APIs (and the LocalAddressSpace::sThisAddressSpace singleton) in libunwind.cpp, plus dependent EHABI exception-dispatch exports in Unwind-EHABI.cpp.
  • Introduce UnwindHelpers::FindUnwindSections() and switch UnixNativeCodeManager to use it (avoiding the now-guarded sThisAddressSpace).
  • Record the patch application in llvm-libunwind-version.txt and enable the new define in the NativeAOT runtime CMake configuration.
Show a summary per file
FileDescription
src/native/external/llvm-libunwind/src/Unwind-EHABI.cppGuards EHABI exception-dispatch exports when _LIBUNWIND_NATIVEAOT is set to avoid references to removed __unw_* APIs.
src/native/external/llvm-libunwind/src/libunwind.cppGuards the public unw_* API surface and the LocalAddressSpace::sThisAddressSpace singleton under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind/src/AddressSpace.hppGuards the LocalAddressSpace::sThisAddressSpace static member declaration under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind-version.txtNotes the applied commit associated with this local patch.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.hDeclares the new UnwindHelpers::FindUnwindSections accessor.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cppImplements FindUnwindSections by delegating to the existing file-scope _addressSpace.
src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cppReplaces use of LocalAddressSpace::sThisAddressSpace.findUnwindSections with UnwindHelpers::FindUnwindSections.
src/coreclr/nativeaot/Runtime/CMakeLists.txtDefines _LIBUNWIND_NATIVEAOT=1 for Unix NativeAOT builds to enable the guarding behavior.
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  • Files reviewed: 8/8 changed files
  • Comments generated: 0
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If it's a negative if !defined(_LIBUNWIND_NATIVEAOT) check everywhere, we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
jkotas
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Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
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we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
Deleting the code creates more conflicts during updates. We won't be able to upstream the deletion either. I think ifdefing is better.
jkotas
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Comment threadsrc/native/external/llvm-libunwind-version.txt
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Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.
sbomerand others
added 2 commits
May 28, 2026 16:55
@sbomer@jkotas
Guard unused llvm-libunwind symbols to avoid duplicates on Android
fde4a5b
NativeAOT uses llvm-libunwind's internal C++ classes directly
(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)
and does not call the public unw_* C API. These symbols conflict with
platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API
symbols NativeAOT does not use:
- libunwind.cpp: wrap the entire file (except debug logging) in
#if !defined(_LIBUNWIND_NATIVEAOT) as a purely additive patch,
making it resilient to upstream llvm-libunwind updates
- Unwind-EHABI.cpp: the C++ exception dispatch functions are also
guarded because they depend on the now-guarded unw_* functions
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()
accessor instead of the now-guarded sThisAddressSpace singleton. This
delegates to the existing file-local LocalAddressSpace instance in
UnwindHelpers.cpp.
Co-authored-by: Jan Kotas <jkotas@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sbomer
Update llvm-libunwind-version.txt
1004d9f
Reference fde4a5b (Guard unused llvm-libunwind symbols).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@jkotas can you please help merge this without squashing?
@jkotas
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merged commit ad724f5
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libunwind-ifdef

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@MichalStrehovsky
Fix ARM32 SIGSEGV: narrow _LIBUNWIND_NATIVEAOT guard in Unwind-EHABI.cpp
5697904
Split the single #if !defined(_LIBUNWIND_NATIVEAOT) guard into two blocks
so that _Unwind_VRS_Get, _Unwind_VRS_Get_Internal, _Unwind_VRS_Set,
_Unwind_VRS_Pop, and ValueAsBitPattern are compiled into the NativeAOT
build. These helpers are called by _Unwind_VRS_Interpret which is the
ARM32 EHABI managed-frame unwinding path in NativeAOT.
PR #128667 accidentally included them inside the guard, causing the
linker to resolve them against libgcc_s.so.1 instead of the in-tree
implementations that understand the NativeAOT ArmUnwindCursor shim,
resulting in SIGSEGV during ARM32 stack unwinding.
The genuinely-unused C++ exception dispatch functions (__aeabi_unwind_cpp_pr*,
unwind_phase1/2, _Unwind_RaiseException, _Unwind_ForcedUnwind, etc.) that
depend on __unw_step and other libunwind.cpp public API remain guarded.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
CopilotAI
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@MichalStrehovsky
Fix ARM32 NativeAOT SIGSEGV: keep VRS helpers and __unw_*_reg outside…
1cd1620
… _LIBUNWIND_NATIVEAOT guard
PR #128667 accidentally excluded _Unwind_VRS_Get/Set/Pop (and their
__unw_get/set_reg/__unw_save_vfp_as_X dependencies) from the NativeAOT
build while leaving _Unwind_VRS_Interpret (their caller) in place.
The linker resolved the exported VRS symbols from libgcc_s.so.1 which
treats ArmUnwindCursor* as a real libgcc context → SIGSEGV on ARM32.
Unwind-EHABI.cpp: Split single NATIVEAOT guard into two blocks so
ValueAsBitPattern and _Unwind_VRS_Set/Get_Internal/Get/Pop sit between
the two guards (always compiled).
libunwind.cpp: Split single NATIVEAOT guard into smaller inner guards
keeping __unw_get_reg, __unw_set_reg, __unw_get_fpreg, __unw_set_fpreg,
__unw_save_vfp_as_X unconditional so they are compiled for NativeAOT.
The singleton, __unw_init_local, __unw_step, __unw_resume, DWARF/FDE
functions, and Apple dynamic sections remain behind the guard.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
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This broke uwinding on arm32. The failure mode is a rather mysterious sigsegv, but pulling down a binary from a failed test run and running nm -D seems to indicate we're linking dynamically against some of GCC's libunwind (@GCC_3.5):
007ca06c D DotNetRuntimeDebugHeader@@V1.0
w _ITM_deregisterTMCloneTable
w _ITM_registerTMCloneTable
U _Unwind_VRS_Get@GCC_3.5
U _Unwind_VRS_Pop@GCC_3.5
U _Unwind_VRS_Set@GCC_3.5
U __aeabi_unwind_cpp_pr0@GCC_3.5
U __aeabi_unwind_cpp_pr1@GCC_3.5
U __aeabi_unwind_cpp_pr2@GCC_3.5
U __clock_gettime64@GLIBC_2.34
U __clock_nanosleep_time64@GLIBC_2.34
U __cxa_atexit@GLIBC_2.4
w __cxa_finalize@GLIBC_2.4
U __errno_location@GLIBC_2.4
U __fcntl_time64@GLIBC_2.34
U __fstat64_time64@GLIBC_2.34
U __getdelim@GLIBC_2.4
... redacted for brevity

Copilot is trying to do something at #128830.
@tannergoodingtannergooding
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@MichalStrehovsky
Revert "Guard unused llvm-libunwind symbols to avoid duplicates on An…
c7d8935
…droid" (#128883)
Resolves#128866.
Reverts #128667
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[NAOT][android] Application linking breaks with NDK r29 because of duplicated libunwind symbols


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// Remove or un-stick sticky/fixed headers that block content
(function() {
function unstick() {
document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) {
if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {
el.style.position = 'static';
el.style.top = 'auto';
el.style.zIndex = 'auto';
}
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}
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observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });
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})();
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '
Guard unused llvm-libunwind symbols to avoid duplicates on Android by sbomer · Pull Request #128667 · dotnet/runtime · GitHub
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Guard unused llvm-libunwind symbols to avoid duplicates on Android - #128667
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Guard unused llvm-libunwind symbols to avoid duplicates on Android#128667
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sbomer:libunwind-ifdef
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NativeAOT uses llvm-libunwind's internal C++ classes directly

(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)

and does not call the public unw_* C API. These symbols conflict with

platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API

symbols NativeAOT does not use:
  • libunwind.cpp: all unw_* functions, unw_local_addr_space, and
    
the LocalAddressSpace::sThisAddressSpace singleton
  • AddressSpace.hpp: sThisAddressSpace static member declaration
  • Unwind-EHABI.cpp: the C++ exception dispatch functions are also
    
guarded because they depend on the now-guarded unw_* functions
    
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()

accessor instead of the now-guarded sThisAddressSpace singleton. This

delegates to the existing file-local LocalAddressSpace instance in

UnwindHelpers.cpp
Fixes#121172
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Pull request overview
This PR updates the NativeAOT build of the vendored llvm-libunwind to avoid duplicate symbol conflicts (notably on Android NDK r29) by compiling out libunwind’s public unw_* entrypoints and related exception-dispatch code that NativeAOT doesn’t use, and by routing NativeAOT’s unwind-section discovery through a runtime-owned helper instead of libunwind’s LocalAddressSpace::sThisAddressSpace singleton.
Changes:
  • Add _LIBUNWIND_NATIVEAOT and use it to guard out unw_* APIs (and the LocalAddressSpace::sThisAddressSpace singleton) in libunwind.cpp, plus dependent EHABI exception-dispatch exports in Unwind-EHABI.cpp.
  • Introduce UnwindHelpers::FindUnwindSections() and switch UnixNativeCodeManager to use it (avoiding the now-guarded sThisAddressSpace).
  • Record the patch application in llvm-libunwind-version.txt and enable the new define in the NativeAOT runtime CMake configuration.
Show a summary per file
FileDescription
src/native/external/llvm-libunwind/src/Unwind-EHABI.cppGuards EHABI exception-dispatch exports when _LIBUNWIND_NATIVEAOT is set to avoid references to removed __unw_* APIs.
src/native/external/llvm-libunwind/src/libunwind.cppGuards the public unw_* API surface and the LocalAddressSpace::sThisAddressSpace singleton under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind/src/AddressSpace.hppGuards the LocalAddressSpace::sThisAddressSpace static member declaration under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind-version.txtNotes the applied commit associated with this local patch.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.hDeclares the new UnwindHelpers::FindUnwindSections accessor.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cppImplements FindUnwindSections by delegating to the existing file-scope _addressSpace.
src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cppReplaces use of LocalAddressSpace::sThisAddressSpace.findUnwindSections with UnwindHelpers::FindUnwindSections.
src/coreclr/nativeaot/Runtime/CMakeLists.txtDefines _LIBUNWIND_NATIVEAOT=1 for Unix NativeAOT builds to enable the guarding behavior.
Copilot's findings
  • Files reviewed: 8/8 changed files
  • Comments generated: 0
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If it's a negative if !defined(_LIBUNWIND_NATIVEAOT) check everywhere, we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
jkotas
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Comment threadsrc/native/external/llvm-libunwind/src/AddressSpace.hpp
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Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
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we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
Deleting the code creates more conflicts during updates. We won't be able to upstream the deletion either. I think ifdefing is better.
jkotas
jkotas
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May 27, 2026
View reviewed changes
Comment threadsrc/native/external/llvm-libunwind-version.txt
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This was referenced May 28, 2026

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Open


This was referenced May 28, 2026

Open


Open

jkotas
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Comment threadsrc/native/external/llvm-libunwind/src/Unwind-EHABI.cpp
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Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.
sbomerand others
added 2 commits
May 28, 2026 16:55
@sbomer@jkotas
Guard unused llvm-libunwind symbols to avoid duplicates on Android
fde4a5b
NativeAOT uses llvm-libunwind's internal C++ classes directly
(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)
and does not call the public unw_* C API. These symbols conflict with
platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API
symbols NativeAOT does not use:
- libunwind.cpp: wrap the entire file (except debug logging) in
#if !defined(_LIBUNWIND_NATIVEAOT) as a purely additive patch,
making it resilient to upstream llvm-libunwind updates
- Unwind-EHABI.cpp: the C++ exception dispatch functions are also
guarded because they depend on the now-guarded unw_* functions
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()
accessor instead of the now-guarded sThisAddressSpace singleton. This
delegates to the existing file-local LocalAddressSpace instance in
UnwindHelpers.cpp.
Co-authored-by: Jan Kotas <jkotas@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sbomer
Update llvm-libunwind-version.txt
1004d9f
Reference fde4a5b (Guard unused llvm-libunwind symbols).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@jkotas can you please help merge this without squashing?
@jkotas
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merged commit ad724f5
into
dotnet:mainMay 29, 2026

164 of 171 checks passed

@sbomer
sbomer
deleted the

libunwind-ifdef

branch
May 29, 2026 16:58
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added this to the 11.0-preview6 milestone
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@MichalStrehovsky
Fix ARM32 SIGSEGV: narrow _LIBUNWIND_NATIVEAOT guard in Unwind-EHABI.cpp
5697904
Split the single #if !defined(_LIBUNWIND_NATIVEAOT) guard into two blocks
so that _Unwind_VRS_Get, _Unwind_VRS_Get_Internal, _Unwind_VRS_Set,
_Unwind_VRS_Pop, and ValueAsBitPattern are compiled into the NativeAOT
build. These helpers are called by _Unwind_VRS_Interpret which is the
ARM32 EHABI managed-frame unwinding path in NativeAOT.
PR #128667 accidentally included them inside the guard, causing the
linker to resolve them against libgcc_s.so.1 instead of the in-tree
implementations that understand the NativeAOT ArmUnwindCursor shim,
resulting in SIGSEGV during ARM32 stack unwinding.
The genuinely-unused C++ exception dispatch functions (__aeabi_unwind_cpp_pr*,
unwind_phase1/2, _Unwind_RaiseException, _Unwind_ForcedUnwind, etc.) that
depend on __unw_step and other libunwind.cpp public API remain guarded.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
CopilotAI
added a commit
that referenced
this pull request
Jun 1, 2026
@MichalStrehovsky
Fix ARM32 NativeAOT SIGSEGV: keep VRS helpers and __unw_*_reg outside…
1cd1620
… _LIBUNWIND_NATIVEAOT guard
PR #128667 accidentally excluded _Unwind_VRS_Get/Set/Pop (and their
__unw_get/set_reg/__unw_save_vfp_as_X dependencies) from the NativeAOT
build while leaving _Unwind_VRS_Interpret (their caller) in place.
The linker resolved the exported VRS symbols from libgcc_s.so.1 which
treats ArmUnwindCursor* as a real libgcc context → SIGSEGV on ARM32.
Unwind-EHABI.cpp: Split single NATIVEAOT guard into two blocks so
ValueAsBitPattern and _Unwind_VRS_Set/Get_Internal/Get/Pop sit between
the two guards (always compiled).
libunwind.cpp: Split single NATIVEAOT guard into smaller inner guards
keeping __unw_get_reg, __unw_set_reg, __unw_get_fpreg, __unw_set_fpreg,
__unw_save_vfp_as_X unconditional so they are compiled for NativeAOT.
The singleton, __unw_init_local, __unw_step, __unw_resume, DWARF/FDE
functions, and Apple dynamic sections remain behind the guard.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
@MichalStrehovsky
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This broke uwinding on arm32. The failure mode is a rather mysterious sigsegv, but pulling down a binary from a failed test run and running nm -D seems to indicate we're linking dynamically against some of GCC's libunwind (@GCC_3.5):
007ca06c D DotNetRuntimeDebugHeader@@V1.0
w _ITM_deregisterTMCloneTable
w _ITM_registerTMCloneTable
U _Unwind_VRS_Get@GCC_3.5
U _Unwind_VRS_Pop@GCC_3.5
U _Unwind_VRS_Set@GCC_3.5
U __aeabi_unwind_cpp_pr0@GCC_3.5
U __aeabi_unwind_cpp_pr1@GCC_3.5
U __aeabi_unwind_cpp_pr2@GCC_3.5
U __clock_gettime64@GLIBC_2.34
U __clock_nanosleep_time64@GLIBC_2.34
U __cxa_atexit@GLIBC_2.4
w __cxa_finalize@GLIBC_2.4
U __errno_location@GLIBC_2.4
U __fcntl_time64@GLIBC_2.34
U __fstat64_time64@GLIBC_2.34
U __getdelim@GLIBC_2.4
... redacted for brevity

Copilot is trying to do something at #128830.
@tannergoodingtannergooding
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Jun 2, 2026
@MichalStrehovsky
Revert "Guard unused llvm-libunwind symbols to avoid duplicates on An…
c7d8935
…droid" (#128883)
Resolves#128866.
Reverts #128667
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[NAOT][android] Application linking breaks with NDK r29 because of duplicated libunwind symbols


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filter: invert(1) hue-rotate(180deg) !important;
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Guard unused llvm-libunwind symbols to avoid duplicates on Android by sbomer · Pull Request #128667 · dotnet/runtime · GitHub
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Guard unused llvm-libunwind symbols to avoid duplicates on Android - #128667
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sbomer:libunwind-ifdef
May 29, 2026
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Guard unused llvm-libunwind symbols to avoid duplicates on Android#128667
jkotas merged 2 commits into
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sbomer:libunwind-ifdef
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NativeAOT uses llvm-libunwind's internal C++ classes directly

(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)

and does not call the public unw_* C API. These symbols conflict with

platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API

symbols NativeAOT does not use:
  • libunwind.cpp: all unw_* functions, unw_local_addr_space, and
    
the LocalAddressSpace::sThisAddressSpace singleton
  • AddressSpace.hpp: sThisAddressSpace static member declaration
  • Unwind-EHABI.cpp: the C++ exception dispatch functions are also
    
guarded because they depend on the now-guarded unw_* functions
    
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()

accessor instead of the now-guarded sThisAddressSpace singleton. This

delegates to the existing file-local LocalAddressSpace instance in

UnwindHelpers.cpp
Fixes#121172
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Pull request overview
This PR updates the NativeAOT build of the vendored llvm-libunwind to avoid duplicate symbol conflicts (notably on Android NDK r29) by compiling out libunwind’s public unw_* entrypoints and related exception-dispatch code that NativeAOT doesn’t use, and by routing NativeAOT’s unwind-section discovery through a runtime-owned helper instead of libunwind’s LocalAddressSpace::sThisAddressSpace singleton.
Changes:
  • Add _LIBUNWIND_NATIVEAOT and use it to guard out unw_* APIs (and the LocalAddressSpace::sThisAddressSpace singleton) in libunwind.cpp, plus dependent EHABI exception-dispatch exports in Unwind-EHABI.cpp.
  • Introduce UnwindHelpers::FindUnwindSections() and switch UnixNativeCodeManager to use it (avoiding the now-guarded sThisAddressSpace).
  • Record the patch application in llvm-libunwind-version.txt and enable the new define in the NativeAOT runtime CMake configuration.
Show a summary per file
FileDescription
src/native/external/llvm-libunwind/src/Unwind-EHABI.cppGuards EHABI exception-dispatch exports when _LIBUNWIND_NATIVEAOT is set to avoid references to removed __unw_* APIs.
src/native/external/llvm-libunwind/src/libunwind.cppGuards the public unw_* API surface and the LocalAddressSpace::sThisAddressSpace singleton under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind/src/AddressSpace.hppGuards the LocalAddressSpace::sThisAddressSpace static member declaration under _LIBUNWIND_NATIVEAOT.
src/native/external/llvm-libunwind-version.txtNotes the applied commit associated with this local patch.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.hDeclares the new UnwindHelpers::FindUnwindSections accessor.
src/coreclr/nativeaot/Runtime/unix/UnwindHelpers.cppImplements FindUnwindSections by delegating to the existing file-scope _addressSpace.
src/coreclr/nativeaot/Runtime/unix/UnixNativeCodeManager.cppReplaces use of LocalAddressSpace::sThisAddressSpace.findUnwindSections with UnwindHelpers::FindUnwindSections.
src/coreclr/nativeaot/Runtime/CMakeLists.txtDefines _LIBUNWIND_NATIVEAOT=1 for Unix NativeAOT builds to enable the guarding behavior.
Copilot's findings
  • Files reviewed: 8/8 changed files
  • Comments generated: 0
@am11
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If it's a negative if !defined(_LIBUNWIND_NATIVEAOT) check everywhere, we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
jkotas
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Comment threadsrc/native/external/llvm-libunwind/src/AddressSpace.hpp
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Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
Comment threadsrc/native/external/llvm-libunwind/src/libunwind.cpp
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we can just delete the code it skips. The idea of this local copy is we apply the patches and keep track of them for possible upstream.
Deleting the code creates more conflicts during updates. We won't be able to upstream the deletion either. I think ifdefing is better.
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Comment threadsrc/native/external/llvm-libunwind/src/Unwind-EHABI.cpp
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Copilot encountered an error and was unable to review this pull request. You can try again by re-requesting a review.
sbomerand others
added 2 commits
May 28, 2026 16:55
@sbomer@jkotas
Guard unused llvm-libunwind symbols to avoid duplicates on Android
fde4a5b
NativeAOT uses llvm-libunwind's internal C++ classes directly
(DwarfInstructions, CompactUnwinder, UnwindCursor, LocalAddressSpace)
and does not call the public unw_* C API. These symbols conflict with
platform libunwind on Android NDK r29.
Add a _LIBUNWIND_NATIVEAOT define that guards out the public API
symbols NativeAOT does not use:
- libunwind.cpp: wrap the entire file (except debug logging) in
#if !defined(_LIBUNWIND_NATIVEAOT) as a purely additive patch,
making it resilient to upstream llvm-libunwind updates
- Unwind-EHABI.cpp: the C++ exception dispatch functions are also
guarded because they depend on the now-guarded unw_* functions
and would cause undefined symbol errors on ARM32
Switch UnixNativeCodeManager to use a new UnwindHelpers::FindUnwindSections()
accessor instead of the now-guarded sThisAddressSpace singleton. This
delegates to the existing file-local LocalAddressSpace instance in
UnwindHelpers.cpp.
Co-authored-by: Jan Kotas <jkotas@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
@sbomer
Update llvm-libunwind-version.txt
1004d9f
Reference fde4a5b (Guard unused llvm-libunwind symbols).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@jkotas can you please help merge this without squashing?
@jkotas
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merged commit ad724f5
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@sbomer
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deleted the

libunwind-ifdef

branch
May 29, 2026 16:58
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@MichalStrehovsky
Fix ARM32 SIGSEGV: narrow _LIBUNWIND_NATIVEAOT guard in Unwind-EHABI.cpp
5697904
Split the single #if !defined(_LIBUNWIND_NATIVEAOT) guard into two blocks
so that _Unwind_VRS_Get, _Unwind_VRS_Get_Internal, _Unwind_VRS_Set,
_Unwind_VRS_Pop, and ValueAsBitPattern are compiled into the NativeAOT
build. These helpers are called by _Unwind_VRS_Interpret which is the
ARM32 EHABI managed-frame unwinding path in NativeAOT.
PR #128667 accidentally included them inside the guard, causing the
linker to resolve them against libgcc_s.so.1 instead of the in-tree
implementations that understand the NativeAOT ArmUnwindCursor shim,
resulting in SIGSEGV during ARM32 stack unwinding.
The genuinely-unused C++ exception dispatch functions (__aeabi_unwind_cpp_pr*,
unwind_phase1/2, _Unwind_RaiseException, _Unwind_ForcedUnwind, etc.) that
depend on __unw_step and other libunwind.cpp public API remain guarded.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
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Fix ARM32 NativeAOT SIGSEGV: keep VRS helpers and __unw_*_reg outside…
1cd1620
… _LIBUNWIND_NATIVEAOT guard
PR #128667 accidentally excluded _Unwind_VRS_Get/Set/Pop (and their
__unw_get/set_reg/__unw_save_vfp_as_X dependencies) from the NativeAOT
build while leaving _Unwind_VRS_Interpret (their caller) in place.
The linker resolved the exported VRS symbols from libgcc_s.so.1 which
treats ArmUnwindCursor* as a real libgcc context → SIGSEGV on ARM32.
Unwind-EHABI.cpp: Split single NATIVEAOT guard into two blocks so
ValueAsBitPattern and _Unwind_VRS_Set/Get_Internal/Get/Pop sit between
the two guards (always compiled).
libunwind.cpp: Split single NATIVEAOT guard into smaller inner guards
keeping __unw_get_reg, __unw_set_reg, __unw_get_fpreg, __unw_set_fpreg,
__unw_save_vfp_as_X unconditional so they are compiled for NativeAOT.
The singleton, __unw_init_local, __unw_step, __unw_resume, DWARF/FDE
functions, and Apple dynamic sections remain behind the guard.
Co-authored-by: MichalStrehovsky <13110571+MichalStrehovsky@users.noreply.github.com>
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This broke uwinding on arm32. The failure mode is a rather mysterious sigsegv, but pulling down a binary from a failed test run and running nm -D seems to indicate we're linking dynamically against some of GCC's libunwind (@GCC_3.5):
007ca06c D DotNetRuntimeDebugHeader@@V1.0
w _ITM_deregisterTMCloneTable
w _ITM_registerTMCloneTable
U _Unwind_VRS_Get@GCC_3.5
U _Unwind_VRS_Pop@GCC_3.5
U _Unwind_VRS_Set@GCC_3.5
U __aeabi_unwind_cpp_pr0@GCC_3.5
U __aeabi_unwind_cpp_pr1@GCC_3.5
U __aeabi_unwind_cpp_pr2@GCC_3.5
U __clock_gettime64@GLIBC_2.34
U __clock_nanosleep_time64@GLIBC_2.34
U __cxa_atexit@GLIBC_2.4
w __cxa_finalize@GLIBC_2.4
U __errno_location@GLIBC_2.4
U __fcntl_time64@GLIBC_2.34
U __fstat64_time64@GLIBC_2.34
U __getdelim@GLIBC_2.4
... redacted for brevity

Copilot is trying to do something at #128830.
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@MichalStrehovsky
Revert "Guard unused llvm-libunwind symbols to avoid duplicates on An…
c7d8935
…droid" (#128883)
Resolves#128866.
Reverts #128667
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@jkotasjkotasjkotas approved these changes
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Successfully merging this pull request may close these issues.

[NAOT][android] Application linking breaks with NDK r29 because of duplicated libunwind symbols


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