| Issue |
173863
|
| Summary |
Clang trunk crashes with assertion failure when break appears inside GNU statement _expression_ used as switch condition
|
| Labels |
clang:frontend,
clang:codegen,
crash-on-valid,
extension:gnu
|
| Assignees |
|
| Reporter |
AbyssStaror
|
### Link for quick verification: https://godbolt.org/z/drWxdodGq
```c
#include <stdio.h>
int foo(int y) {
switch (1) {
case 1:
switch (({ if (y) {
break;
}
2; })) {
case 2:
return 0;
default:
return -1;
}
default:
return -2;
}
}
```
Go back to clang 2.9.
Clang trunk crashes during CodeGen with `Assertion '!BreakContinueStack.empty() && "break stmt not in a loop or switch!"'` failed
when a GNU statement _expression_ ((`{ ... }`)) containing a break statement is used as the controlling _expression_ of a switch.
The break is syntactically accepted and should target the enclosing switch, but during IR generation `EmitBreakStmt` is reached with an empty `BreakContinueStack`, indicating incorrect control-flow context handling for `StmtExpr` inside switch conditions.
## Stack dump
```console
clang++: /root/llvm-project/llvm/tools/clang/lib/CodeGen/CGStmt.cpp:1757: void clang::CodeGen::CodeGenFunction::EmitBreakStmt(const clang::BreakStmt&): Assertion `!BreakContinueStack.empty() && "break stmt not in a loop or switch!"' 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>:5:5: LLVM IR generation of declaration 'foo'
3. <source>:5:5: Generating code for declaration 'foo'
4. <source>:10:22: LLVM IR generation of compound statement ('{}')
5. <source>:10:31: LLVM IR generation of compound statement ('{}')
#0 0x0000000004301458 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4301458)
#1 0x00000000042fe884 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42fe884)
#2 0x0000000004243628 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
#3 0x000079e2a6042520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#4 0x000079e2a60969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
#5 0x000079e2a6042476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
#6 0x000079e2a60287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
#7 0x000079e2a602871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
#8 0x000079e2a6039e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#9 0x00000000047fd5f4 (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47fd5f4)
#10 0x0000000004814227 clang::CodeGen::CodeGenFunction::EmitSimpleStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4814227)
#11 0x000000000480b7d1 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x480b7d1)
#12 0x0000000004813dcb clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4813dcb)
#13 0x0000000004814368 clang::CodeGen::CodeGenFunction::EmitSimpleStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4814368)
#14 0x000000000480b7d1 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x480b7d1)
#15 0x0000000004813510 clang::CodeGen::CodeGenFunction::EmitIfStmt(clang::IfStmt const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4813510)
#16 0x000000000480b991 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x480b991)
#17 0x0000000004813dcb clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4813dcb)
#18 0x000000000481413d clang::CodeGen::CodeGenFunction::EmitCompoundStmt(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x481413d)
#19 0x00000000046cfccd (anonymous namespace)::ScalarExprEmitter::VisitStmtExpr(clang::StmtExpr const*) (.isra.0) CGExprScalar.cpp:0:0
#20 0x00000000046e03bf clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#21 0x00000000046e4d2c clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x46e4d2c)
#22 0x000000000480c396 clang::CodeGen::CodeGenFunction::EmitSwitchStmt(clang::SwitchStmt const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x480c396)
#23 0x000000000480bb51 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x480bb51)
#24 0x000000000480cdac clang::CodeGen::CodeGenFunction::EmitSwitchStmt(clang::SwitchStmt const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x480cdac)
#25 0x000000000480bb51 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x480bb51)
#26 0x0000000004813dcb clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4813dcb)
#27 0x000000000487be0e clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x487be0e)
#28 0x000000000488d264 clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x488d264)
#29 0x00000000048fb150 clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48fb150)
#30 0x00000000048f5df4 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48f5df4)
#31 0x00000000048f65d3 clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48f65d3)
#32 0x0000000004901b63 clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#33 0x0000000004c65379 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#34 0x0000000004c55ea4 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c55ea4)
#35 0x0000000006a1e374 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6a1e374)
#36 0x0000000004c62788 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c62788)
#37 0x0000000004f58e05 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4f58e05)
#38 0x0000000004ed909e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ed909e)
#39 0x000000000505318d clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x505318d)
#40 0x0000000000de63ec cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xde63ec)
#41 0x0000000000ddce3a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&, llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem>) driver.cpp:0:0
#42 0x0000000000ddcfbd 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
#43 0x0000000004cd4e59 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
#44 0x0000000004243ac4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4243ac4)
#45 0x0000000004cd546f 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
#46 0x0000000004c95f52 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c95f52)
#47 0x0000000004c96efe 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+++0x4c96efe)
#48 0x0000000004c9e355 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c9e355)
#49 0x0000000000de27e1 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xde27e1)
#50 0x0000000000c8d114 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8d114)
#51 0x000079e2a6029d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#52 0x000079e2a6029e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#53 0x0000000000ddc8d5 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xddc8d5)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134
```
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