"Type punning" some aarch64 SVE via pointers causes an internal compiler error

[pinskia]

Take:

#include <arm_sve.h>

svint8_t f(svuint8x4_t s) {
	return *reinterpret_cast<svint8_t*>(&s);
}

Will cause an internal compile error:

fatal error: error in backend: Invalid size request on a scalable vector.
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-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -S -target aarch64-linux-gnu --gcc-toolchain=/opt/compiler-explorer/arm64/gcc-12.2.0/aarch64-unknown-linux-gnu --sysroot=/opt/compiler-explorer/arm64/gcc-12.2.0/aarch64-unknown-linux-gnu/aarch64-unknown-linux-gnu/sysroot -fcolor-diagnostics -fno-crash-diagnostics -march=armv9-a+sve2 -O1 <source>
1.	<eof> parser at end of file
2.	Code generation
3.	Running pass 'Function Pass Manager' on module '<source>'.
4.	Running pass 'AArch64 Instruction Selection' on function '@_Z1f11svuint8x4_t'
 #0 0x0000000003624838 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3624838)
 #1 0x0000000003622984 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3622984)
 #2 0x0000000003570323 llvm::CrashRecoveryContext::HandleExit(int) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3570323)
 #3 0x000000000361a36e llvm::sys::Process::Exit(int, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x361a36e)
 #4 0x0000000000c22476 (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc22476)
 #5 0x0000000003579373 llvm::report_fatal_error(llvm::Twine const&, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3579373)
 #6 0x00000000035794d8 (/opt/compiler-explorer/clang-trunk/bin/clang+++0x35794d8)
 #7 0x00000000035c8a4d (/opt/compiler-explorer/clang-trunk/bin/clang+++0x35c8a4d)
 #8 0x00000000035c8a6c llvm::TypeSize::operator unsigned long() const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x35c8a6c)
 #9 0x000000000465b796 llvm::SelectionDAGBuilder::EmitFuncArgumentDbgValue(llvm::Value const*, llvm::DILocalVariable*, llvm::DIExpression*, llvm::DILocation*, llvm::SelectionDAGBuilder::FuncArgumentDbgValueKind, llvm::SDValue const&)::'lambda0'(llvm::ArrayRef<std::pair<unsigned int, llvm::TypeSize>>)::operator()(llvm::ArrayRef<std::pair<unsigned int, llvm::TypeSize>>) const SelectionDAGBuilder.cpp:0:0
#10 0x0000000004674246 llvm::SelectionDAGBuilder::EmitFuncArgumentDbgValue(llvm::Value const*, llvm::DILocalVariable*, llvm::DIExpression*, llvm::DILocation*, llvm::SelectionDAGBuilder::FuncArgumentDbgValueKind, llvm::SDValue const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4674246)
#11 0x00000000046750e1 llvm::SelectionDAGBuilder::handleDebugValue(llvm::ArrayRef<llvm::Value const*>, llvm::DILocalVariable*, llvm::DIExpression*, llvm::DebugLoc, unsigned int, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x46750e1)
#12 0x0000000004679567 llvm::SelectionDAGBuilder::visitDbgInfo(llvm::Instruction const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4679567)
#13 0x00000000046b48d9 llvm::SelectionDAGBuilder::visit(llvm::Instruction const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x46b48d9)
#14 0x000000000472dd16 llvm::SelectionDAGISel::SelectBasicBlock(llvm::ilist_iterator_w_bits<llvm::ilist_detail::node_options<llvm::Instruction, false, false, void, true>, false, true>, llvm::ilist_iterator_w_bits<llvm::ilist_detail::node_options<llvm::Instruction, false, false, void, true>, false, true>, bool&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x472dd16)
#15 0x000000000472f348 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x472f348)
#16 0x0000000004731b29 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (.part.0) SelectionDAGISel.cpp:0:0
#17 0x0000000002ab83b0 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0
#18 0x0000000002fe9a52 llvm::FPPassManager::runOnFunction(llvm::Function&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x2fe9a52)
#19 0x0000000002fe9bd1 llvm::FPPassManager::runOnModule(llvm::Module&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x2fe9bd1)
#20 0x0000000002feb7f0 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x2feb7f0)
#21 0x0000000003892149 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>>, clang::BackendConsumer*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3892149)
#22 0x0000000003e6cfb1 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3e6cfb1)
#23 0x0000000005cf7719 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5cf7719)
#24 0x0000000003e6c415 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3e6c415)
#25 0x0000000004100a51 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4100a51)
#26 0x000000000407d00b clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x407d00b)
#27 0x00000000041e2c33 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x41e2c33)
#28 0x0000000000c242a6 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc242a6)
#29 0x0000000000c1cbdd ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#30 0x0000000003eb39f9 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#31 0x0000000003570223 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3570223)
#32 0x0000000003eb3c19 clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#33 0x0000000003e7b9f7 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3e7b9f7)
#34 0x0000000003e7c3ad clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3e7c3ad)
#35 0x0000000003e8610c clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3e8610c)
#36 0x0000000000c21521 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc21521)
#37 0x0000000000b18064 main (/opt/compiler-explorer/clang-trunk/bin/clang+++0xb18064)

[llvmbot]

@llvm/issue-subscribers-backend-aarch64

Author: Andrew Pinski (pinskia)

Take: ``` #include <arm_sve.h>

svint8_t f(svuint8x4_t s) {
return reinterpret_cast<svint8_t>(&s);
}

Will cause an internal compile error:

fatal error: error in backend: Invalid size request on a scalable vector.
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-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -S -target aarch64-linux-gnu --gcc-toolchain=/opt/compiler-explorer/arm64/gcc-12.2.0/aarch64-unknown-linux-gnu --sysroot=/opt/compiler-explorer/arm64/gcc-12.2.0/aarch64-unknown-linux-gnu/aarch64-unknown-linux-gnu/sysroot -fcolor-diagnostics -fno-crash-diagnostics -march=armv9-a+sve2 -O1 <source>

1. <eof> parser at end of file
2. Code generation
3. Running pass 'Function Pass Manager' on module '<source>'.
4. Running pass 'AArch64 Instruction Selection' on function '@_Z1f11svuint8x4_t'
   #0 0x0000000003624838 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3624838)
   #1 0x0000000003622984 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3622984)
   #2 0x0000000003570323 llvm::CrashRecoveryContext::HandleExit(int) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3570323)
   #3 0x000000000361a36e llvm::sys::Process::Exit(int, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x361a36e)
   #4 0x0000000000c22476 (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc22476)
   #5 0x0000000003579373 llvm::report_fatal_error(llvm::Twine const&, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3579373)
   #6 0x00000000035794d8 (/opt/compiler-explorer/clang-trunk/bin/clang+++0x35794d8)
   #7 0x00000000035c8a4d (/opt/compiler-explorer/clang-trunk/bin/clang+++0x35c8a4d)
   #8 0x00000000035c8a6c llvm::TypeSize::operator unsigned long() const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x35c8a6c)
   #9 0x000000000465b796 llvm::SelectionDAGBuilder::EmitFuncArgumentDbgValue(llvm::Value const*, llvm::DILocalVariable*, llvm::DIExpression*, llvm::DILocation*, llvm::SelectionDAGBuilder::FuncArgumentDbgValueKind, llvm::SDValue const&)::'lambda0'(llvm::ArrayRef<std::pair<unsigned int, llvm::TypeSize>>)::operator()(llvm::ArrayRef<std::pair<unsigned int, llvm::TypeSize>>) const SelectionDAGBuilder.cpp:0:0
   #10 0x0000000004674246 llvm::SelectionDAGBuilder::EmitFuncArgumentDbgValue(llvm::Value const*, llvm::DILocalVariable*, llvm::DIExpression*, llvm::DILocation*, llvm::SelectionDAGBuilder::FuncArgumentDbgValueKind, llvm::SDValue const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4674246)
   #11 0x00000000046750e1 llvm::SelectionDAGBuilder::handleDebugValue(llvm::ArrayRef<llvm::Value const*>, llvm::DILocalVariable*, llvm::DIExpression*, llvm::DebugLoc, unsigned int, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x46750e1)
   #12 0x0000000004679567 llvm::SelectionDAGBuilder::visitDbgInfo(llvm::Instruction const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4679567)
   #13 0x00000000046b48d9 llvm::SelectionDAGBuilder::visit(llvm::Instruction const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x46b48d9)
   #14 0x000000000472dd16 llvm::SelectionDAGISel::SelectBasicBlock(llvm::ilist_iterator_w_bits<llvm::ilist_detail::node_options<llvm::Instruction, false, false, void, true>, false, true>, llvm::ilist_iterator_w_bits<llvm::ilist_detail::node_options<llvm::Instruction, false, false, void, true>, false, true>, bool&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x472dd16)
   #15 0x000000000472f348 llvm::SelectionDAGISel::SelectAllBasicBlocks(llvm::Function const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x472f348)
   #16 0x0000000004731b29 llvm::SelectionDAGISel::runOnMachineFunction(llvm::MachineFunction&) (.part.0) SelectionDAGISel.cpp:0:0
   #17 0x0000000002ab83b0 llvm::MachineFunctionPass::runOnFunction(llvm::Function&) (.part.0) MachineFunctionPass.cpp:0:0
   #18 0x0000000002fe9a52 llvm::FPPassManager::runOnFunction(llvm::Function&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x2fe9a52)
   #19 0x0000000002fe9bd1 llvm::FPPassManager::runOnModule(llvm::Module&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x2fe9bd1)
   #20 0x0000000002feb7f0 llvm::legacy::PassManagerImpl::run(llvm::Module&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x2feb7f0)
   #21 0x0000000003892149 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>>, clang::BackendConsumer*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3892149)
   #22 0x0000000003e6cfb1 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3e6cfb1)
   #23 0x0000000005cf7719 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5cf7719)
   #24 0x0000000003e6c415 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3e6c415)
   #25 0x0000000004100a51 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4100a51)
   #26 0x000000000407d00b clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x407d00b)
   #27 0x00000000041e2c33 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x41e2c33)
   #28 0x0000000000c242a6 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc242a6)
   #29 0x0000000000c1cbdd ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
   #30 0x0000000003eb39f9 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>, bool) const::'lambda'()>(long) Job.cpp:0:0
   #31 0x0000000003570223 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3570223)
   #32 0x0000000003eb3c19 clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>, bool) const (.part.0) Job.cpp:0:0
   #33 0x0000000003e7b9f7 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3e7b9f7)
   #34 0x0000000003e7c3ad clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3e7c3ad)
   #35 0x0000000003e8610c clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3e8610c)
   #36 0x0000000000c21521 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc21521)
   #37 0x0000000000b18064 main (/opt/compiler-explorer/clang-trunk/bin/clang+++0xb18064)

</details>

[davemgreen]

I believe this happens for passing any x4 type: https://godbolt.org/z/Y9PbYdWso

[vhscampos]

This happens in the debug info producer at the part where it processes function arguments. It tries to query the argument's size, but fails as the argument is of an SVE type. SVE types are sizeless according to the ACLE.