<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/75690>75690</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang-18 crash: Assertion `Reg >= X86::FP0 && Reg <= X86::FP6 && "Expected FP register!"' failed.
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

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

<pre>
    Clang-18 with -O -msse -mno-sse2 crashes on the test case.
Compiler explorer(assertion trunck): https://godbolt.org/z/6KKoKc6vW
```
$cat mutant.c
void a();
void b(__attribute__((__vector_size__(2 * sizeof(double)))) double c) {
  if (c[1])
    a();
}

$clang-18 -O -msse -mno-sse2 mutant.c
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: /usr/lib/llvm-18/bin/clang -cc1 -triple x86_64-pc-linux-gnu -emit-obj -dumpdir a- -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name mutant.c -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -target-feature +sse -target-feature -sse2 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/root/code/my_code/diff_coverage/combine_test/mutant_dir_gcc_testset -fcoverage-compilation-dir=/root/code/my_code/diff_coverage/combine_test/mutant_dir_gcc_testset -resource-dir /usr/lib/llvm-18/lib/clang/18 -internal-isystem /usr/lib/llvm-18/lib/clang/18/include -internal-isystem /usr/local/include -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O1 -ferror-limit 19 -fgnuc-version=4.2.1 -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/mutant-6f7d05.o -x c mutant.c
1. <eof> parser at end of file
2.      Code generation
3.      Running pass 'Function Pass Manager' on module 'mutant.c'.
4.      Running pass 'X86 FP Stackifier' on function '@b'
 #0 0x00007f19f92b1266 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xd2b266)
 #1 0x00007f19f92af170 llvm::sys::RunSignalHandlers() (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xd29170)
 #2 0x00007f19f92b1940 (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xd2b940)
 #3 0x00007f1a03d92980 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x12980)
 #4 0x00007f19fbe7524e (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0x38ef24e)
 #5 0x00007f19fbe73bbc (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0x38edbbc)
 #6 0x00007f19f9665552 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0x10df552)
 #7 0x00007f19f93f70df llvm::FPPassManager::runOnFunction(llvm::Function&) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xe710df)
 #8 0x00007f19f93fcdc3 llvm::FPPassManager::runOnModule(llvm::Module&) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xe76dc3)
 #9 0x00007f19f93f77d4 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/usr/lib/llvm-18/bin/../lib/libLLVM-18.so.1+0xe717d4)
#10 0x00007f1a01a9409f 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>>) (/usr/lib/llvm-18/bin/../lib/libclang-cpp.so.18+0x1ade09f)
#11 0x00007f1a01e2a5fe (/usr/lib/llvm-18/bin/../lib/libclang-cpp.so.18+0x1e745fe)
#12 0x00007f1a00a46866 clang::ParseAST(clang::Sema&, bool, bool) (/usr/lib/llvm-18/bin/../lib/libclang-cpp.so.18+0xa90866)
#13 0x00007f1a0289e645 clang::FrontendAction::Execute() (/usr/lib/llvm-18/bin/../lib/libclang-cpp.so.18+0x28e8645)
#14 0x00007f1a0281ccc4 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/usr/lib/llvm-18/bin/../lib/libclang-cpp.so.18+0x2866cc4)
#15 0x00007f1a029191c0 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/usr/lib/llvm-18/bin/../lib/libclang-cpp.so.18+0x29631c0)
#16 0x0000557ccd9d8837 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/usr/lib/llvm-18/bin/clang+0x13837)
#17 0x0000557ccd9d5905 (/usr/lib/llvm-18/bin/clang+0x10905)
#18 0x0000557ccd9d4a8e clang_main(int, char**, llvm::ToolContext const&) (/usr/lib/llvm-18/bin/clang+0xfa8e)
#19 0x0000557ccd9e2f32 main (/usr/lib/llvm-18/bin/clang+0x1df32)
#20 0x00007f19f7795c87 __libc_start_main /build/glibc-CVJwZb/glibc-2.27/csu/../csu/libc-start.c:344:0
#21 0x0000557ccd9d21ea _start (/usr/lib/llvm-18/bin/clang+0xd1ea)
clang-18: error: unable to execute command: Segmentation fault (core dumped)
clang-18: error: clang frontend command failed due to signal (use -v to see invocation)
Ubuntu clang version 18.0.0 (++20231018091808+48a53509e851-1~exp1~20231018091910.1571)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
clang-18: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-18: note: diagnostic msg: /tmp/mutant-4396df.c
clang-18: note: diagnostic msg: /tmp/mutant-4396df.sh
clang-18: note: diagnostic msg: 

********************
```
</pre>
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