| Issue |
173558
|
| Summary |
Crash in llvm::FixedVectorType::get: Assertion NumElts > 0 failed when using "k" constraint with a compound literal in inline assembly
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
AbyssStaror
|
### Link for quick verification: https://godbolt.org/z/PY7hq7G4G
```c
int main() {
int x = 5;
struct S { char c[16]; };
__asm__ __volatile__(
"movq %0, %1"
:
: "m"(x), "k"(&(struct S){})
:
);
}
```
Go back to `clang 19.1.0 (assertions)`. May relate to https://github.com/llvm/llvm-project/issues/171795.
During LLVM IR generation in `clang::CodeGen::CodeGenFunction::EmitAsmStmt`, the compiler attempts to map the input operand to a type compatible with the "k" constraint. It appears the logic incorrectly attempts to create a `FixedVectorType` with zero elements, triggering the assertion.
## Stack dump:
```console
clang++: /root/llvm-project/llvm/lib/IR/Type.cpp:803: static llvm::FixedVectorType* llvm::FixedVectorType::get(llvm::Type*, unsigned int): Assertion `NumElts > 0 && "#Elements of a VectorType must be greater than 0"' 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: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -g -o /app/output.s -mllvm --x86-asm-syntax=intel -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics <source>
1. <eof> parser at end of file
2. <source>:1:5: LLVM IR generation of declaration 'main'
3. <source>:1:5: Generating code for declaration 'main'
#0 0x00000000042ecc08 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42ecc08)
#1 0x00000000042ea034 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42ea034)
#2 0x000000000422edd8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
#3 0x00007238da842520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#4 0x00007238da8969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
#5 0x00007238da842476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
#6 0x00007238da8287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
#7 0x00007238da82871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
#8 0x00007238da839e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#9 0x0000000003c4f906 llvm::FixedVectorType::get(llvm::Type*, unsigned int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3c4f906)
#10 0x00000000047f28bc clang::CodeGen::CodeGenFunction::EmitAsmStmt(clang::AsmStmt const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47f28bc)
#11 0x00000000047f7361 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47f7361)
#12 0x00000000047ff5cb clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47ff5cb)
#13 0x000000000486760e clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x486760e)
#14 0x0000000004878a64 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4878a64)
#15 0x00000000048e6950 clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48e6950)
#16 0x00000000048e15f4 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48e15f4)
#17 0x00000000048e1dd3 clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48e1dd3)
#18 0x00000000048ed363 clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#19 0x0000000004c50b79 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#20 0x0000000004c416a4 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c416a4)
#21 0x0000000006a089f4 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a089f4)
#22 0x0000000004c4df88 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c4df88)
#23 0x0000000004f44885 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f44885)
#24 0x0000000004ec4b1e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ec4b1e)
#25 0x000000000503ec0d clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x503ec0d)
#26 0x0000000000de5b1c cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xde5b1c)
#27 0x0000000000ddc56a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>) driver.cpp:0:0
#28 0x0000000000ddc6ed int llvm::function_ref<int (llvm::SmallVectorImpl<char const*>&)>::callback_fn<clang_main(int, char**, llvm::ToolContext const&)::'lambda'(llvm::SmallVectorImpl<char const*>&)>(long, llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#29 0x0000000004cc08d9 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
#30 0x000000000422f274 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x422f274)
#31 0x0000000004cc0eef 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
#32 0x0000000004c819d2 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c819d2)
#33 0x0000000004c8297e clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c8297e)
#34 0x0000000004c89dd5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c89dd5)
#35 0x0000000000de1f11 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xde1f11)
#36 0x0000000000c8cf64 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8cf64)
#37 0x00007238da829d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#38 0x00007238da829e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#39 0x0000000000ddc005 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xddc005)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134
```
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