Revert "[Clang,debuginfo] added vtt parameter in destructor DISubroutineType (#130674)"

This reverts commit 27c1aa9.

See comments on PR. After this change, Clang now asserts like this:

clang: ../llvm/include/llvm/IR/Metadata.h:1435: const MDOperand &llvm::MDNode::getOperand(unsigned int) const: Assertion `I < getNumOperands() && "Out of range"' failed.
...
 #8 0x000055f345c4e4cb clang::CodeGen::CGDebugInfo::getOrCreateInstanceMethodType()
 #9 0x000055f345c5ba4f clang::CodeGen::CGDebugInfo::EmitFunctionDecl()
 #10 0x000055f345b52519 clang::CodeGen::CodeGenModule::EmitExternalFunctionDeclaration()

This is due to pre-existing jankiness in the way BPF emits extra
declarations for debug info, but we should rollback and then fix forward.

Author: rnk

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -2018,17 +2018,8 @@ CGDebugInfo::getOrCreateMethodType(const CXXMethodDecl *Method,
   return getOrCreateInstanceMethodType(ThisType, Func, Unit);
 }
 
-llvm::DISubroutineType *CGDebugInfo::getOrCreateMethodTypeForDestructor(
-    const CXXMethodDecl *Method, llvm::DIFile *Unit, QualType FNType) {
-  const FunctionProtoType *Func = FNType->getAs<FunctionProtoType>();
-  // skip the first param since it is also this
-  return getOrCreateInstanceMethodType(Method->getThisType(), Func, Unit, true);
-}
-
-llvm::DISubroutineType *
-CGDebugInfo::getOrCreateInstanceMethodType(QualType ThisPtr,
-                                           const FunctionProtoType *Func,
-                                           llvm::DIFile *Unit, bool SkipFirst) {
+llvm::DISubroutineType *CGDebugInfo::getOrCreateInstanceMethodType(
+    QualType ThisPtr, const FunctionProtoType *Func, llvm::DIFile *Unit) {
   FunctionProtoType::ExtProtoInfo EPI = Func->getExtProtoInfo();
   Qualifiers &Qc = EPI.TypeQuals;
   Qc.removeConst();
@@ -2068,7 +2059,7 @@ CGDebugInfo::getOrCreateInstanceMethodType(QualType ThisPtr,
   }
 
   // Copy rest of the arguments.
-  for (unsigned i = (SkipFirst ? 2 : 1), e = Args.size(); i != e; ++i)
+  for (unsigned i = 1, e = Args.size(); i != e; ++i)
     Elts.push_back(Args[i]);
 
   // Attach FlagObjectPointer to the explicit "this" parameter.
@@ -4381,12 +4372,6 @@ llvm::DISubroutineType *CGDebugInfo::getOrCreateFunctionType(const Decl *D,
     // subprogram DIE will miss DW_AT_decl_file and DW_AT_decl_line fields.
     return DBuilder.createSubroutineType(DBuilder.getOrCreateTypeArray({}));
 
-  if (const auto *Method = dyn_cast<CXXDestructorDecl>(D)) {
-    // Read method type from 'FnType' because 'D.getType()' does not cover
-    // implicit arguments for destructors.
-    return getOrCreateMethodTypeForDestructor(Method, F, FnType);
-  }
-
   if (const auto *Method = dyn_cast<CXXMethodDecl>(D))
     return getOrCreateMethodType(Method, F);
 

clang/lib/CodeGen/CGDebugInfo.h

@@ -249,14 +249,9 @@ class CGDebugInfo {
   /// to get a method type which includes \c this pointer.
   llvm::DISubroutineType *getOrCreateMethodType(const CXXMethodDecl *Method,
                                                 llvm::DIFile *F);
-
-  llvm::DISubroutineType *
-  getOrCreateMethodTypeForDestructor(const CXXMethodDecl *Method,
-                                     llvm::DIFile *F, QualType FNType);
-
   llvm::DISubroutineType *
   getOrCreateInstanceMethodType(QualType ThisPtr, const FunctionProtoType *Func,
-                                llvm::DIFile *Unit, bool SkipFirst = false);
+                                llvm::DIFile *Unit);
   llvm::DISubroutineType *
   getOrCreateFunctionType(const Decl *D, QualType FnType, llvm::DIFile *F);
   /// \return debug info descriptor for vtable.

clang/lib/CodeGen/CodeGenModule.cpp

@@ -5837,15 +5837,24 @@ void CodeGenModule::EmitExternalVarDeclaration(const VarDecl *D) {
     }
 }
 
+static GlobalDecl getBaseVariantGlobalDecl(const FunctionDecl *FD) {
+  if (auto const *CD = dyn_cast<const CXXConstructorDecl>(FD))
+    return GlobalDecl(CD, CXXCtorType::Ctor_Base);
+  else if (auto const *DD = dyn_cast<const CXXDestructorDecl>(FD))
+    return GlobalDecl(DD, CXXDtorType::Dtor_Base);
+  return GlobalDecl(FD);
+}
+
 void CodeGenModule::EmitExternalFunctionDeclaration(const FunctionDecl *FD) {
   if (CGDebugInfo *DI = getModuleDebugInfo())
     if (getCodeGenOpts().hasReducedDebugInfo()) {
+      GlobalDecl GD = getBaseVariantGlobalDecl(FD);
       auto *Ty = getTypes().ConvertType(FD->getType());
-      StringRef MangledName = getMangledName(FD);
+      StringRef MangledName = getMangledName(GD);
       auto *Fn = cast<llvm::Function>(
-          GetOrCreateLLVMFunction(MangledName, Ty, FD, /* ForVTable */ false));
+          GetOrCreateLLVMFunction(MangledName, Ty, GD, /* ForVTable */ false));
       if (!Fn->getSubprogram())
-        DI->EmitFunctionDecl(FD, FD->getLocation(), FD->getType(), Fn);
+        DI->EmitFunctionDecl(GD, FD->getLocation(), FD->getType(), Fn);
     }
 }