This demo illustrates the issue

$ cat > test.c <<EOF

struct QCryptoAkCipher {
    void (*free)(struct QCryptoAkCipher *akcipher);
};

void qcrypto_akcipher_free(struct QCryptoAkCipher *akcipher);
void qcrypto_akcipher_free(struct QCryptoAkCipher *akcipher)
{
    akcipher->free(akcipher);
}
EOF

$ clang -c  -o test  test.c -fzero-call-used-regs=all -O2
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: clang -c -o test /test.c -fzero-call-used-regs=all -O2
1.	<eof> parser at end of file
2.	Code generation
3.	Running pass 'Function Pass Manager' on module '/test.c'.
4.	Running pass 'Prologue/Epilogue Insertion & Frame Finalization' on function '@qcrypto_akcipher_free'
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  libLLVM-17.so      0x00007fb947feeb7a llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 58
1  libLLVM-17.so      0x00007fb947fec534 llvm::sys::RunSignalHandlers() + 84
2  libLLVM-17.so      0x00007fb947f23d14
3  libc.so.6          0x00007fb947351db0
4  libLLVM-17.so      0x00007fb94855cf9f
5  libLLVM-17.so      0x00007fb9484288cc llvm::MachineFunctionPass::runOnFunction(llvm::Function&) + 828
6  libLLVM-17.so      0x00007fb948165575 llvm::FPPassManager::runOnFunction(llvm::Function&) + 1285
7  libLLVM-17.so      0x00007fb94816c2e3 llvm::FPPassManager::runOnModule(llvm::Module&) + 51
8  libLLVM-17.so      0x00007fb948165c2d llvm::legacy::PassManagerImpl::run(llvm::Module&) + 1085
9  libclang-cpp.so.17 0x00007fb94f7f6825 clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::StringRef, llvm::Module*, clang::BackendAction, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>) + 3445
10 libclang-cpp.so.17 0x00007fb94fbf3048
11 libclang-cpp.so.17 0x00007fb94e59f526 clang::ParseAST(clang::Sema&, bool, bool) + 598
12 libclang-cpp.so.17 0x00007fb9507b5c86 clang::FrontendAction::Execute() + 102
13 libclang-cpp.so.17 0x00007fb950722e40 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 752
14 libclang-cpp.so.17 0x00007fb9508366d4 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 580
15 clang              0x0000000000412911 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) + 4097
16 clang              0x000000000040fd25
17 libclang-cpp.so.17 0x00007fb95035cbfd
18 libLLVM-17.so      0x00007fb947f23a54 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) + 148
19 libclang-cpp.so.17 0x00007fb95035c627 clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const + 375
20 libclang-cpp.so.17 0x00007fb950322fee clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const + 878
21 libclang-cpp.so.17 0x00007fb950323257 clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const + 167
22 libclang-cpp.so.17 0x00007fb9503405da clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) + 474
23 clang              0x000000000040f568 clang_main(int, char**, llvm::ToolContext const&) + 11752
24 clang              0x000000000041c036 main + 54
25 libc.so.6          0x00007fb94733ceb0
26 libc.so.6          0x00007fb94733cf60 __libc_start_main + 128
27 clang              0x000000000040c425 _start + 37
clang: error: clang frontend command failed with exit code 139 (use -v to see invocation)
clang version 17.0.6 (CentOS 17.0.6-5.el9)
Target: x86_64-redhat-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
clang: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang: note: diagnostic msg: /tmp/test-28f292.c
clang: note: diagnostic msg: /tmp/test-28f292.sh
clang: note: diagnostic msg: 

********************


Does not crash with -O0
Does not crash on non-x86 architecture
Does not crash on Fedora 38 with clang 16

This impacts ability to build QEMU (git master) with clang which now enables -fzero-call-used-regs by default

Reproducible: Always