Missing CIRGen for CXXDefaultArgExpr

[ljtodo]

Maybe the implicit construct semantics of C++ are not supported, and ClangIR may not properly parse implicitly called constructors, causing problems in handling default parameters or lvalue operations called by implicit constructors.

https://godbolt.org/

C++ source:

#include <iostream> 
#include <fstream> 
#include <cstring> 
#include <map> 
#include <math.h> 
using namespace std;

size_t pictureDataSize = 0; 
void *pictureHostData; 
void *pictureDeviceData;

void ReadPictureTotHost(const char *picturePath) 
{
  string fileName = picturePath; 
  ifstream binFile(fileName, ifstream::binary); 
  binFile.seekg(0, binFile.end); 
  pictureDataSize = binFile.tellg(); 
  binFile.seekg(0, binFile.beg); 
  binFile.read((char*)pictureHostData, pictureDataSize); 
  binFile.close();
}

the output:

clang version 20.0.0git (https://github.com/llvm/clangir.git b414f2b7d8b8b97b626d5b0b2bf448a3f61d39ff)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/compiler-explorer/clang-clangir-trunk-20241108/bin
Build config: +assertions
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/10
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/11
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
 (in-process)
 "/opt/compiler-explorer/clang-clangir-trunk-20241108/bin/clang-20" -cc1 -triple x86_64-unknown-linux-gnu -S -disable-free -clear-ast-before-backend -main-file-name example.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -fno-verbose-asm -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debug-info-kind=constructor -dwarf-version=4 -debugger-tuning=gdb -fdebug-compilation-dir=/app -v -fcoverage-compilation-dir=/app -resource-dir /opt/compiler-explorer/clang-clangir-trunk-20241108/lib/clang/20 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/x86_64-linux-gnu/c++/11 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/backward -internal-isystem /opt/compiler-explorer/clang-clangir-trunk-20241108/lib/clang/20/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -ferror-limit 19 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -fcolor-diagnostics -fclangir -emit-cir -mllvm --x86-asm-syntax=intel -mmlir --mlir-print-ir-before-all -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /app/output.s -x c++ <source>
clang -cc1 version 20.0.0git based upon LLVM 20.0.0git default target x86_64-unknown-linux-gnu
ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11
 /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/x86_64-linux-gnu/c++/11
 /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/backward
 /opt/compiler-explorer/clang-clangir-trunk-20241108/lib/clang/20/include
 /usr/local/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
loc("<source>":14:21): error: l-value not implemented for 'CXXDefaultArgExpr'
clang++: /root/llvm-project/clang/lib/CIR/CodeGen/CIRGenExpr.cpp:2548: cir::LValue cir::CIRGenFunction::buildLValue(const clang::Expr*): Assertion `0 && "not implemented"' 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-clangir-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -fno-verbose-asm -S -Xclang -fclangir -fcolor-diagnostics -fno-crash-diagnostics -Xclang -emit-cir -v -mmlir --mlir-print-ir-before-all <source>
1.	<eof> parser at end of file
2.	<source>:12:6: LLVM IR generation of declaration 'ReadPictureTotHost'
 #0 0x0000000002bd8cf8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x2bd8cf8)
 #1 0x0000000002bd69fc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x2bd69fc)
 #2 0x0000000002b2c508 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x000077bb98442520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x000077bb984969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x000077bb98442476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x000077bb984287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x000077bb9842871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x000077bb98439e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x00000000042ac60d cir::CIRGenFunction::buildLValue(clang::Expr const*) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x42ac60d)
#10 0x00000000042ae33b cir::CIRGenFunction::buildReferenceBindingToExpr(clang::Expr const*) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x42ae33b)
#11 0x00000000042797ed cir::CIRGenFunction::buildCallArg(cir::CallArgList&, clang::Expr const*, clang::QualType) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x42797ed)
#12 0x0000000004279f26 cir::CIRGenFunction::buildCallArgs(cir::CallArgList&, cir::CIRGenFunction::PrototypeWrapper, llvm::iterator_range<clang::Stmt::CastIterator<clang::Expr, clang::Expr const* const, clang::Stmt const* const>>, cir::CIRGenFunction::AbstractCallee, unsigned int, cir::CIRGenFunction::EvaluationOrder) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x4279f26)
#13 0x0000000004365b2f cir::CIRGenFunction::buildCXXConstructorCall(clang::CXXConstructorDecl const*, clang::CXXCtorType, bool, bool, cir::AggValueSlot, clang::CXXConstructExpr const*) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x4365b2f)
#14 0x00000000042e1cee cir::CIRGenFunction::buildCXXConstructExpr(clang::CXXConstructExpr const*, cir::AggValueSlot) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x42e1cee)
#15 0x00000000042ce59e (anonymous namespace)::AggExprEmitter::VisitCXXConstructExpr(clang::CXXConstructExpr const*) CIRGenExprAgg.cpp:0:0
#16 0x00000000042d7688 (anonymous namespace)::AggExprEmitter::VisitCastExpr(clang::CastExpr*) CIRGenExprAgg.cpp:0:0
#17 0x00000000042dabb8 (anonymous namespace)::AggExprEmitter::VisitExprWithCleanups(clang::ExprWithCleanups*) CIRGenExprAgg.cpp:0:0
#18 0x00000000042d3774 cir::CIRGenFunction::buildAggExpr(clang::Expr const*, cir::AggValueSlot) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x42d3774)
#19 0x0000000004289afe cir::CIRGenFunction::buildExprAsInit(clang::Expr const*, clang::ValueDecl const*, cir::LValue, bool) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x4289afe)
#20 0x000000000428df79 cir::CIRGenFunction::buildAutoVarInit(cir::CIRGenFunction::AutoVarEmission const&) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x428df79)
#21 0x00000000042940af cir::CIRGenFunction::buildVarDecl(clang::VarDecl const&) (.part.0) CIRGenDecl.cpp:0:0
#22 0x000000000429457e cir::CIRGenFunction::buildDecl(clang::Decl const&) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x429457e)
#23 0x000000000431ccbf cir::CIRGenFunction::buildDeclStmt(clang::DeclStmt const&) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x431ccbf)
#24 0x0000000004322edf cir::CIRGenFunction::buildStmt(clang::Stmt const*, bool, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x4322edf)
#25 0x00000000043257f7 cir::CIRGenFunction::buildCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, cir::AggValueSlot) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x43257f7)
#26 0x00000000042ff9c0 cir::CIRGenFunction::buildFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x42ff9c0)
#27 0x000000000430b7a5 cir::CIRGenFunction::generateCode(clang::GlobalDecl, mlir::cir::FuncOp, cir::CIRGenFunctionInfo const&) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x430b7a5)
#28 0x0000000004252652 cir::CIRGenModule::buildGlobalFunctionDefinition(clang::GlobalDecl, mlir::Operation*) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x4252652)
#29 0x0000000004253d27 cir::CIRGenModule::buildGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x4253d27)
#30 0x0000000004254346 cir::CIRGenModule::buildTopLevelDecl(clang::Decl*) (.part.0) CIRGenModule.cpp:0:0
#31 0x00000000042385d9 cir::CIRGenerator::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x42385d9)
#32 0x000000000411caaf cir::CIRGenConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x411caaf)
#33 0x000000000658b184 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x658b184)
#34 0x000000000411ed48 cir::CIRGenAction::ExecuteAction() (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x411ed48)
#35 0x00000000037f9819 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x37f9819)
#36 0x00000000037765be clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x37765be)
#37 0x00000000038df9bc clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x38df9bc)
#38 0x0000000001090e1f cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x1090e1f)
#39 0x0000000001088cfa ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#40 0x000000000357f599 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
#41 0x0000000002b2c9b4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x2b2c9b4)
#42 0x000000000357fb8f 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
#43 0x0000000003545d1d clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x3545d1d)
#44 0x0000000003546e0d clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x3546e0d)
#45 0x000000000354e2b5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x354e2b5)
#46 0x000000000108de39 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x108de39)
#47 0x0000000000fa17f4 main (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0xfa17f4)
#48 0x000077bb98429d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#49 0x000077bb98429e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#50 0x00000000010887ae _start (/opt/compiler-explorer/clang-clangir-trunk/bin/clang+++0x10887ae)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

[ljtodo]

Do you have this problem?

[bcardosolopes]

Looks like we need to implement CIRGen for CXXDefaultArgExpr

[ljtodo]

Looks like we need to implement CIRGen for CXXDefaultArgExpr

Thank you for your busy schedule to respond the question. Here are my recent thoughts and hope to help solve the problem.
According to the error information, an error occurs when Clang performs AST analysis on the line string fileName = picturePath;.
I'm guessing whether Clang may have a problem handling default parameters or lvalue operations called by implicit constructors.
So is it possible that these are the reasons:

1. may not properly enable modern C++ standards (such as C++ 11 or later)
2. Unimplemented AST operation: CXXDefaultArgExpr
3. Problems with memory allocation operations: The code also involves memory operations such as aclrtMallocHost and binFile.read. These calls may raise a check on pointer operations:

• Does Clang properly support conversions between char* types and std::string?
• Is the binary file operation flow handled correctly in the AST analysis?

[ghehg]

@ljtodo Thank you for reporting the issue! To be clear, I don't think its Clang front end's problem. From crash stackframe, it shows its a problem generating ClangIR for DefaultArgExpr AST. ClangIR is an IR (MLIR dialect) that is under development, it wouldn't be a surprise that some AST structs fail to generate ClangIR (a.k.a CIR).
The traditional Clang compiler (without -fclangir option) would directly translate AST into LLVMIR, then target code. It should compile your sample code without problem.

[ljtodo]

Thanks！