Overly dramatic error when trying to use wrong mcmodel with aarch64 targets.

[qookei]

Bugzilla Link	46772
Version	10.0
OS	Linux
Attachments	empty-8d13f1.sh
CC	@qookei,@zygoloid

Extended Description

When compiling any bit of code (even an empty file) with for example "-target aarch64-none-elf" or any other aarch64 target, if "-mcmodel=kernel" is specified, the compiler prints an overly dramatic fatal error with a stack trace, and a plea to submit a bug report.

Sample output (no, there actually is no stack trace printed in this case for whatever reason):
$ touch empty.cpp
$ clang++ -target aarch64-none-elf -mcmodel=kernel empty.cpp
fatal error: error in backend: Only small, tiny and large code models are allowed on AArch64
clang-10: error: clang frontend command failed with exit code 70 (use -v to see invocation)
clang version 10.0.0
Target: aarch64-none-unknown-elf
Thread model: posix
InstalledDir: /usr/bin
clang-10: note: diagnostic msg: PLEASE submit a bug report to and include the crash backtrace, preprocessed source, and associated run script.
clang-10: note: diagnostic msg:

---

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-10: note: diagnostic msg: /tmp/empty-8d13f1.cpp
clang-10: note: diagnostic msg: /tmp/empty-8d13f1.sh
clang-10: note: diagnostic msg:

---

$

Attached is the empty-8d13f1.sh file; following is the empty-8d13f1.cpp contents:

1 ""

1 "empty.cpp"

[Endilll]

-mcmodel=kernel is not accepted since Clang 16: https://godbolt.org/z/Gn54nxPET
But does it count as a fix?
Clang 15 crash:

fatal error: error in backend: Only small, tiny and large code models are allowed on AArch64

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: /opt/compiler-explorer/clang-assertions-15.0.0/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-12.2.0 -fcolor-diagnostics -fno-crash-diagnostics -mcmodel=kernel -target aarch64-none-elf <source>
1.	<eof> parser at end of file
 #0 0x0000561c9db1dfd4 PrintStackTraceSignalHandler(void*) Signals.cpp:0:0
 #1 0x0000561c9db1bd1c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x3e78d1c)
 #2 0x0000561c9da533c3 llvm::CrashRecoveryContext::HandleExit(int) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x3db03c3)
 #3 0x0000561c9db137d2 llvm::sys::Process::Exit(int, bool) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x3e707d2)
 #4 0x0000561c9b07b790 LLVMErrorHandler(void*, char const*, bool) cc1_main.cpp:0:0
 #5 0x0000561c9da5b77a llvm::report_fatal_error(llvm::Twine const&, bool) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x3db877a)
 #6 0x0000561c9da5b90e (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x3db890e)
 #7 0x0000561c9b0bd2f9 llvm::AArch64TargetMachine::AArch64TargetMachine(llvm::Target const&, llvm::Triple const&, llvm::StringRef, llvm::StringRef, llvm::TargetOptions const&, llvm::Optional<llvm::Reloc::Model>, llvm::Optional<llvm::CodeModel::Model>, llvm::CodeGenOpt::Level, bool, bool) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x141a2f9)
 #8 0x0000561c9b0bd3a0 llvm::RegisterTargetMachine<llvm::AArch64leTargetMachine>::Allocator(llvm::Target const&, llvm::Triple const&, llvm::StringRef, llvm::StringRef, llvm::TargetOptions const&, llvm::Optional<llvm::Reloc::Model>, llvm::Optional<llvm::CodeModel::Model>, llvm::CodeGenOpt::Level, bool) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x141a3a0)
 #9 0x0000561c9deda90c (anonymous namespace)::EmitAssemblyHelper::CreateTargetMachine(bool) BackendUtil.cpp:0:0
#10 0x0000561c9dee108d clang::EmitBackendOutput(clang::DiagnosticsEngine&, clang::HeaderSearchOptions const&, clang::CodeGenOptions const&, clang::TargetOptions const&, clang::LangOptions const&, llvm::StringRef, llvm::Module*, clang::BackendAction, std::unique_ptr<llvm::raw_pwrite_stream, std::default_delete<llvm::raw_pwrite_stream>>) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x423e08d)
#11 0x0000561c9edde7db clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x513b7db)
#12 0x0000561ca0076779 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x63d3779)
#13 0x0000561c9eddd1b8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x513a1b8)
#14 0x0000561c9e67ff19 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x49dcf19)
#15 0x0000561c9e609dde clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x4966dde)
#16 0x0000561c9e75f7d3 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x4abc7d3)
#17 0x0000561c9b07c9e0 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x13d99e0)
#18 0x0000561c9b075a98 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#19 0x0000561c9e479539 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#20 0x0000561c9da5328c llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x3db028c)
#21 0x0000561c9e479c4f clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#22 0x0000561c9e443c39 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x47a0c39)
#23 0x0000561c9e44475d clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x47a175d)
#24 0x0000561c9e44e7fc clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x47ab7fc)
#25 0x0000561c9b07ad43 clang_main(int, char**) (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x13d7d43)
#26 0x00007fadba581083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#27 0x0000561c9b07568e _start (/opt/compiler-explorer/clang-assertions-15.0.0/bin/clang+++0x13d268e)
clang-15: error: clang frontend command failed with exit code 70 (use -v to see invocation)

[llvmbot]

@llvm/issue-subscribers-backend-aarch64

[c-rhodes]

as per previous comment, this no longer crashes and now fails gracefully. This can be closed.