r188642 - Revert "Revert "DebugInfo: Omit debug info for dynamic classes in TUs that do not have the vtable for that class""

[Adrian Prantl]

Hi David,

This patch adds several blocks of code without any explanatory comments, which makes it hard to understand what’s going on. Would you mind commenting a bit on what you are doing here?

I’m thinking particularly of
> 
> --- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Sun Aug 18 12:59:12 2013
> @@ -644,8 +644,24 @@ llvm::DIDescriptor CGDebugInfo::createCo
> 
>   if (const RecordDecl *RD = dyn_cast<RecordDecl>(Context)) {
>     if (!RD->isDependentType()) {
> -      llvm::DIType Ty = getOrCreateLimitedType(
> -          CGM.getContext().getRecordType(RD)->castAs<RecordType>(), getOrCreateMainFile());
> +      llvm::DICompositeType T(getTypeOrNull(CGM.getContext().getRecordType(RD)));
> +      llvm::DICompositeType Ty(getOrCreateLimitedType(
> +          CGM.getContext().getRecordType(RD)->castAs<RecordType>(),
> +          getOrCreateMainFile()));
> +      if (!Ty.getTypeArray().getNumElements()) {
> +        if (T) {
> +          llvm::DIArray PrevMem = T.getTypeArray();
> +          unsigned NumElements = PrevMem.getNumElements();
> +          if (NumElements == 1 && !PrevMem.getElement(0))
> +            NumElements = 0;
> +          SmallVector<llvm::Value *, 16> EltTys;
> +          EltTys.reserve(NumElements);
> +          for (unsigned i = 0; i != NumElements; ++i)
> +            EltTys.push_back(PrevMem.getElement(i));
> +          llvm::DIArray Elements = DBuilder.getOrCreateArray(EltTys);
> +          Ty.setTypeArray(Elements);
> +        }
> +      }
>       return llvm::DIDescriptor(Ty);
>     }
>   }
> @@ -865,7 +881,7 @@ CollectRecordLambdaFields(const CXXRecor
>   }
> }

and

> -/// getStaticDataMemberDeclaration - If D is an out-of-class definition of
> -/// a static data member of a class, find its corresponding in-class
> -/// declaration.
> -llvm::DIDerivedType CGDebugInfo::getStaticDataMemberDeclaration(const VarDecl *D) {
> -  if (D->isStaticDataMember()) {
> -    llvm::DenseMap<const Decl *, llvm::WeakVH>::iterator
> -      MI = StaticDataMemberCache.find(D->getCanonicalDecl());
> -    if (MI != StaticDataMemberCache.end())
> -      // Verify the info still exists.
> -      if (llvm::Value *V = MI->second)
> -        return llvm::DIDerivedType(cast<llvm::MDNode>(V));
> +/// If D is an out-of-class definition of a static data member of a class, find
> +/// its corresponding in-class declaration.
> +llvm::DIDerivedType
> +CGDebugInfo::getOrCreateStaticDataMemberDeclarationOrNull(const VarDecl *D) {
> +  if (!D->isStaticDataMember())
> +    return llvm::DIDerivedType();
> +  llvm::DenseMap<const Decl *, llvm::WeakVH>::iterator MI =
> +      StaticDataMemberCache.find(D->getCanonicalDecl());
> +  if (MI != StaticDataMemberCache.end()) {
> +    assert(MI->second && "Static data member declaration should still exist");
> +    return llvm::DIDerivedType(cast<llvm::MDNode>(MI->second));
> +  }
> +  llvm::DICompositeType Ctxt(
> +      getContextDescriptor(cast<Decl>(D->getDeclContext())));
> +  llvm::DIDerivedType T = CreateRecordStaticField(D, Ctxt);
> +  Ctxt.addMember(T);
> +  return T;
> +}
> +
> +llvm::DIDerivedType
> +CGDebugInfo::getOrCreateStaticDataMemberDeclaration(const VarDecl *D,
> +                                            llvm::DICompositeType Ctxt) {
> +  llvm::DenseMap<const Decl *, llvm::WeakVH>::iterator MI =
> +      StaticDataMemberCache.find(D->getCanonicalDecl());
> +  if (MI != StaticDataMemberCache.end()) {
> +    assert(MI->second && "Static data member declaration should still exist");
> +    return llvm::DIDerivedType(cast<llvm::MDNode>(MI->second));
>   }
> -  return llvm::DIDerivedType();
> +  return CreateRecordStaticField(D, Ctxt);
> }


and

> @@ -3108,7 +3163,7 @@ void CGDebugInfo::EmitGlobalVariable(con
>     return;
>   llvm::DIGlobalVariable GV = DBuilder.createStaticVariable(
>       Unit, Name, Name, Unit, getLineNumber(VD->getLocation()), Ty, true, Init,
> -      getStaticDataMemberDeclaration(cast<VarDecl>(VD)));
> +      getOrCreateStaticDataMemberDeclarationOrNull(cast<VarDecl>(VD)));
>   DeclCache.insert(std::make_pair(VD->getCanonicalDecl(), llvm::WeakVH(GV)));
> }

thanks,
Adrian