Reland "[codeview] Reference types in type parent scopes"

Summary:
Original description (https://reviews.llvm/org/D69924)
Without this change, when a nested tag type of any kind (enum, class,
struct, union) is used as a variable type, it is emitted without
emitting the parent type. In CodeView, parent types point to their inner
types, and inner types do not point back to their parents. We already
walk over all of the parent scopes to build the fully qualified name.
This change simply requests their type indices as we go along to enusre
they are all emitted.

Now, while walking over the parent scopes, add the types to
DeferredCompleteTypes, since they might already be in the process of
being emitted.

Fixes PR43905

Reviewers: rnk, amccarth

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78249

1 files changed, 21 insertions, 13 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index ca349cb..7c2673a 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -310,12 +310,19 @@ static StringRef getPrettyScopeName(const DIScope *Scope) {
   return StringRef();
 }
 
-static const DISubprogram *getQualifiedNameComponents(
+const DISubprogram *CodeViewDebug::collectParentScopeNames(
     const DIScope *Scope, SmallVectorImpl<StringRef> &QualifiedNameComponents) {
   const DISubprogram *ClosestSubprogram = nullptr;
   while (Scope != nullptr) {
     if (ClosestSubprogram == nullptr)
       ClosestSubprogram = dyn_cast<DISubprogram>(Scope);
+
+    // If a type appears in a scope chain, make sure it gets emitted. The
+    // frontend will be responsible for deciding if this should be a forward
+    // declaration or a complete type.
+    if (const auto *Ty = dyn_cast<DICompositeType>(Scope))
+      DeferredCompleteTypes.push_back(Ty);
+
     StringRef ScopeName = getPrettyScopeName(Scope);
     if (!ScopeName.empty())
       QualifiedNameComponents.push_back(ScopeName);
@@ -324,7 +331,7 @@ static const DISubprogram *getQualifiedNameComponents(
   return ClosestSubprogram;
 }
 
-static std::string getQualifiedName(ArrayRef<StringRef> QualifiedNameComponents,
+static std::string formatNestedName(ArrayRef<StringRef> QualifiedNameComponents,
                                     StringRef TypeName) {
   std::string FullyQualifiedName;
   for (StringRef QualifiedNameComponent :
@@ -336,10 +343,16 @@ static std::string getQualifiedName(ArrayRef<StringRef> QualifiedNameComponents,
   return FullyQualifiedName;
 }
 
-static std::string getFullyQualifiedName(const DIScope *Scope, StringRef Name) {
+std::string CodeViewDebug::getFullyQualifiedName(const DIScope *Scope,
+                                                 StringRef Name) {
   SmallVector<StringRef, 5> QualifiedNameComponents;
-  getQualifiedNameComponents(Scope, QualifiedNameComponents);
-  return getQualifiedName(QualifiedNameComponents, Name);
+  collectParentScopeNames(Scope, QualifiedNameComponents);
+  return formatNestedName(QualifiedNameComponents, Name);
+}
+
+std::string CodeViewDebug::getFullyQualifiedName(const DIScope *Ty) {
+  const DIScope *Scope = Ty->getScope();
+  return getFullyQualifiedName(Scope, getPrettyScopeName(Ty));
 }
 
 struct CodeViewDebug::TypeLoweringScope {
@@ -354,11 +367,6 @@ struct CodeViewDebug::TypeLoweringScope {
   CodeViewDebug &CVD;
 };
 
-static std::string getFullyQualifiedName(const DIScope *Ty) {
-  const DIScope *Scope = Ty->getScope();
-  return getFullyQualifiedName(Scope, getPrettyScopeName(Ty));
-}
-
 TypeIndex CodeViewDebug::getScopeIndex(const DIScope *Scope) {
   // No scope means global scope and that uses the zero index.
   if (!Scope || isa<DIFile>(Scope))
@@ -1477,12 +1485,12 @@ void CodeViewDebug::addToUDTs(const DIType *Ty) {
   if (!shouldEmitUdt(Ty))
     return;
 
-  SmallVector<StringRef, 5> QualifiedNameComponents;
+  SmallVector<StringRef, 5> ParentScopeNames;
   const DISubprogram *ClosestSubprogram =
-      getQualifiedNameComponents(Ty->getScope(), QualifiedNameComponents);
+      collectParentScopeNames(Ty->getScope(), ParentScopeNames);
 
   std::string FullyQualifiedName =
-      getQualifiedName(QualifiedNameComponents, getPrettyScopeName(Ty));
+      formatNestedName(ParentScopeNames, getPrettyScopeName(Ty));
 
   if (ClosestSubprogram == nullptr) {
     GlobalUDTs.emplace_back(std::move(FullyQualifiedName), Ty);