Debug Info: define a DIRef template.

Specialize the constructors for DIRef<DIScope> and DIRef<DIType> to make sure
the Value is indeed a scope ref and a type ref.

Use DIScopeRef for DIScope::getContext and DIType::getContext and use DITypeRef
for getContainingType and getClassType.

DIScope::generateRef now returns a DIScopeRef instead of a "Value *" for
readability and type safety.

llvm-svn: 190418

3 files changed, 23 insertions, 28 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 7db6df0e19a..608ce6a5688 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2644,8 +2644,3 @@ void DwarfDebug::emitDebugStrDWO() {
   InfoHolder.emitStrings(Asm->getObjFileLowering().getDwarfStrDWOSection(),
                          OffSec, StrSym);
 }
-
-/// Find the MDNode for the given scope reference.
-DIScope DwarfDebug::resolve(DIScopeRef SRef) const {
-  return SRef.resolve(TypeIdentifierMap);
-}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index e026c668135..6c13b9ec6f9 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -684,7 +684,10 @@ public:
   unsigned getDwarfVersion() const { return DwarfVersion; }
 
   /// Find the MDNode for the given scope reference.
-  DIScope resolve(DIScopeRef SRef) const;
+  template <typename T>
+  T resolve(DIRef<T> Ref) const {
+    return Ref.resolve(TypeIdentifierMap);
+  }
 
   /// isSubprogramContext - Return true if Context is either a subprogram
   /// or another context nested inside a subprogram.
diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index 51c9e58b2d7..87984a09759 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -725,13 +725,13 @@ void DICompositeType::addMember(DIDescriptor D) {
 
 /// Generate a reference to this DIType. Uses the type identifier instead
 /// of the actual MDNode if possible, to help type uniquing.
-Value *DIScope::generateRef() {
+DIScopeRef DIScope::generateRef() {
   if (!isCompositeType())
-    return *this;
+    return DIScopeRef(*this);
   DICompositeType DTy(DbgNode);
   if (!DTy.getIdentifier())
-    return *this;
-  return DTy.getIdentifier();
+    return DIScopeRef(*this);
+  return DIScopeRef(DTy.getIdentifier());
 }
 
 /// \brief Set the containing type.
@@ -1432,26 +1432,14 @@ void DIVariable::printExtendedName(raw_ostream &OS) const {
   }
 }
 
-DIScopeRef::DIScopeRef(const Value *V) : Val(V) {
+/// Specialize constructor to make sure it has the correct type.
+template <>
+DIRef<DIScope>::DIRef(const Value *V) : Val(V) {
   assert(isScopeRef(V) && "DIScopeRef should be a MDString or MDNode");
 }
-
-/// Given a DITypeIdentifierMap, tries to find the corresponding
-/// DIScope for a DIScopeRef.
-DIScope DIScopeRef::resolve(const DITypeIdentifierMap &Map) const {
-  if (!Val)
-    return DIScope();
-
-  if (const MDNode *MD = dyn_cast<MDNode>(Val))
-    return DIScope(MD);
-
-  const MDString *MS = cast<MDString>(Val);
-  // Find the corresponding MDNode.
-  DITypeIdentifierMap::const_iterator Iter = Map.find(MS);
-  assert(Iter != Map.end() && "Identifier not in the type map?");
-  assert(DIType(Iter->second).isType() &&
-         "MDNode in DITypeIdentifierMap should be a DIType.");
-  return DIScope(Iter->second);
+template <>
+DIRef<DIType>::DIRef(const Value *V) : Val(V) {
+  assert(isTypeRef(V) && "DITypeRef should be a MDString or MDNode");
 }
 
 /// Specialize getFieldAs to handle fields that are references to DIScopes.
@@ -1459,3 +1447,12 @@ template <>
 DIScopeRef DIDescriptor::getFieldAs<DIScopeRef>(unsigned Elt) const {
   return DIScopeRef(getField(DbgNode, Elt));
 }
+/// Specialize getFieldAs to handle fields that are references to DITypes.
+template <>
+DITypeRef DIDescriptor::getFieldAs<DITypeRef>(unsigned Elt) const {
+  return DITypeRef(getField(DbgNode, Elt));
+}
+
+DIScopeRef DIType::getContext() const {
+  return getFieldAs<DIScopeRef>(2);
+}