<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/54412>54412</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang crash during codefen of thunk function types
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang:codegen,
            crash
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          omjavaid
      </td>
    </tr>
</table>

<pre>
    Clang code generation fails with an assertion failure in CodeGen/CGVTables.cpp
This came up while building pytorch using clang-cl on Windows Arm64 platform but it is also reproducible using tot clang-cl on Ubuntu 18.04/x86_64. Seems like there was an effort to fix https://reviews.llvm.org/D100388

Crash report below:

clang-cl: /home/omair/work/lldb/lldb-dev/llvm-project/clang/lib/CodeGen/CGVTables.cpp:533: llvm::Constant *clang::CodeGen::CodeGenVTables::maybeEmitThunk(clang::GlobalDecl, const clang::ThunkInfo &, bool): Assertion `OldThunkFn->isDeclaration() && "Shouldn't replace non-declaration"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: ./host-linux/bin/clang-cl -cc1 -triple aarch64-pc-windows-msvc19.14.0 -emit-obj -mincremental-linker-compatible --mrelax-relocations -disable-free -main-file-name conv.cpp -mrelocation-model static -mframe-pointer=none -relaxed-aliasing -fmath-errno -fno-rounding-math -mconstructor-aliases -target-cpu generic -target-feature +neon -target-abi aapcs -fallow-half-arguments-and-returns -D_MT -D_DLL --dependent-lib=msvcrt --dependent-lib=oldnames --show-includes -sys-header-deps -stack-protector 2 -fcxx-exceptions -fexceptions -fexternc-nounwind -fdiagnostics-format msvc -ffunction-sections -fcoverage-compilation-dir=C:\\kg\\python_test\\github_packages\\pytorch\\build -D ADD_BREAKPAD_SIGNAL_HANDLER -D AT_PER_OPERATOR_HEADERS -D CPUINFO_SUPPORTED_PLATFORM=0 -D FMT_HEADER_ONLY=1 -D MINIZ_DISABLE_ZIP_READER_CRC32_CHECKS -D ONNXIFI_ENABLE_EXT=1 -D ONNX_ML=1 -D ONNX_NAMESPACE=onnx_torch -D USE_EXTERNAL_MZCRC -D WIN32_LEAN_AND_MEAN -D _CRT_SECURE_NO_DEPRECATE=1 -D torch_cpu_EXPORTS -D WIN32 -D _WINDOWS -D NDEBUG -D USE_KINETO -D LIBKINETO_NOCUPTI -D SYMBOLICATE_MOBILE_DEBUG_HANDLE -D EDGE_PROFILER_USE_KINETO -D NDEBUG -D NDEBUG -D USE_GCC_GET_CPUID -D TH_HAVE_THREAD -D NOMINMAX -D CAFFE2_BUILD_MAIN_LIB -D ONNX_BUILD_MAIN_LIB -O2 -Wno-deprecated-declarations -w -fdeprecated-macro -fdebug-compilation-dir=C:\\kg\\python_test\\github_packages\\pytorch\\build -ferror-limit 19 -fno-use-cxa-atexit -fms-extensions -fms-compatibility -fms-compatibility-version=19.14 -std=c++14 -fdelayed-template-parsing -finline-functions -vectorize-loops -vectorize-slp -faddrsig -x c++ conv-9e476c.cpp
1.      <eof> parser at end of file
2.      Per-file LLVM IR generation
 #0 0x000000000608d293 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (./host-linux/bin/clang-cl+0x608d293)
 #1 0x000000000608b02e llvm::sys::RunSignalHandlers() (./host-linux/bin/clang-cl+0x608b02e)
 #2 0x000000000608d61f SignalHandler(int) Signals.cpp:0:0
 #3 0x00007f3d86f0a980 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x12980)
 #4 0x00007f3d859b3e87 raise /build/glibc-uZu3wS/glibc-2.27/signal/../sysdeps/unix/sysv/linux/raise.c:51:0
 #5 0x00007f3d859b57f1 abort /build/glibc-uZu3wS/glibc-2.27/stdlib/abort.c:81:0
 #6 0x00007f3d859a53fa __assert_fail_base /build/glibc-uZu3wS/glibc-2.27/assert/assert.c:89:0
 #7 0x00007f3d859a5472 (/lib/x86_64-linux-gnu/libc.so.6+0x30472)
 #8 0x00000000064d81a8 clang::CodeGen::CodeGenVTables::maybeEmitThunk(clang::GlobalDecl, clang::ThunkInfo const&, bool) (./host-linux/bin/clang-cl+0x64d81a8)
 #9 0x00000000064d8967 clang::CodeGen::CodeGenVTables::addVTableComponent(clang::CodeGen::ConstantArrayBuilder&, clang::VTableLayout const&, unsigned int, llvm::Constant*, unsigned int&, unsigned int, bool) (./host-linux/bin/clang-cl+0x64d8967)
#10 0x00000000064d93e7 clang::CodeGen::CodeGenVTables::createVTableInitializer(clang::CodeGen::ConstantStructBuilder&, clang::VTableLayout const&, llvm::Constant*, bool) (./host-linux/bin/clang-cl+0x64d93e7)
#11 0x0000000006848491 (anonymous namespace)::MicrosoftCXXABI::emitVTableDefinitions(clang::CodeGen::CodeGenVTables&, clang::CXXRecordDecl const*) MicrosoftCXXABI.cpp:0:0
#12 0x00000000064dac39 clang::CodeGen::CodeGenModule::EmitDeferredVTables() (./host-linux/bin/clang-cl+0x64dac39)
#13 0x0000000006379ebf clang::CodeGen::CodeGenModule::EmitDeferred() (./host-linux/bin/clang-cl+0x6379ebf)
#14 0x00000000063782e9 clang::CodeGen::CodeGenModule::Release() (./host-linux/bin/clang-cl+0x63782e9)
#15 0x0000000006bd0074 (anonymo
us namespace)::CodeGeneratorImpl::HandleTranslationUnit(clang::ASTContext&) ModuleBuilder.cpp:0:0
#16 0x0000000006bcd519 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) CodeGenAction.cpp:0:0
#17 0x0000000007d0a594 clang::ParseAST(clang::Sema&, bool, bool) (./host-linux/bin/clang-cl+0x7d0a594)
#18 0x0000000006b01a60 clang::FrontendAction::Execute() (./host-linux/bin/clang-cl+0x6b01a60)
#19 0x0000000006a7812f clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (./host-linux/bin/clang-cl+0x6a7812f)
#20 0x0000000006bc72e3 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (./host-linux/bin/clang-cl+0x6bc72e3)
#21 0x0000000003c500b0 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (./host-linux/bin/clang-cl+0x3c500b0)
#22 0x0000000003c4da20 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#23 0x0000000003c4d70c main (./host-linux/bin/clang-cl+0x3c4d70c)
#24 0x00007f3d85996c87 __libc_start_main /build/glibc-uZu3wS/glibc-2.27/csu/../csu/libc-start.c:344:0
#25 0x0000000003c4a74a _start (./host-linux/bin/clang-cl+0x3c4a74a)
Aborted (core dumped)

[conv-9e476c.zip](https://github.com/llvm/llvm-project/files/8283393/conv-9e476c.zip)
</pre>
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