Debug Info: Use identifier to reference DIType in base type field of

ptr_to_member.

We introduce a new class DITypeRef that represents a reference to a DIType.
It wraps around a Value*, which can be either an identifier in MDString
or an actual MDNode. The class has a helper function "resolve" that
finds the actual MDNode for a given DITypeRef.

We specialize getFieldAs to return a field that is a reference to a
DIType. To correctly access the base type field of ptr_to_member,
getClassType now calls getFieldAs<DITypeRef> to return a DITypeRef.

Also add a typedef for DITypeIdentifierMap and a helper
generateDITypeIdentifierMap in DebugInfo.h. In DwarfDebug.cpp, we keep
a DITypeIdentifierMap and call generateDITypeIdentifierMap to actually
populate the map.

Verifier is updated accordingly.

llvm-svn: 190081

3 files changed, 14 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 4c95e140969..6db54d2fafb 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -905,7 +905,7 @@ void CompileUnit::constructTypeDIE(DIE &Buffer, DIDerivedType DTy) {
 
   if (Tag == dwarf::DW_TAG_ptr_to_member_type)
       addDIEEntry(&Buffer, dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4,
-                  getOrCreateTypeDIE(DTy.getClassType()));
+                  getOrCreateTypeDIE(DD->resolve(DTy.getClassType())));
   // Add source line info if available and TyDesc is not a forward declaration.
   if (!DTy.isForwardDecl())
     addSourceLine(&Buffer, DTy);
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index f97ddcb5a84..57ad489970d 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -823,6 +823,7 @@ void DwarfDebug::beginModule() {
   NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
   if (!CU_Nodes)
     return;
+  TypeIdentifierMap = generateDITypeIdentifierMap(CU_Nodes);
 
   // Emit initial sections so we can reference labels later.
   emitSectionLabels();
@@ -2631,3 +2632,8 @@ void DwarfDebug::emitDebugStrDWO() {
   InfoHolder.emitStrings(Asm->getObjFileLowering().getDwarfStrDWOSection(),
                          OffSec, StrSym);
 }
+
+/// Find the MDNode for the given type reference.
+MDNode *DwarfDebug::resolve(DITypeRef TRef) const {
+  return TRef.resolve(TypeIdentifierMap);
+}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 97a454ac9da..0258fdc3dbb 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -450,6 +450,9 @@ class DwarfDebug {
   // Holder for the skeleton information.
   DwarfUnits SkeletonHolder;
 
+  // Maps from a type identifier to the actual MDNode.
+  DITypeIdentifierMap TypeIdentifierMap;
+
 private:
 
   void addScopeVariable(LexicalScope *LS, DbgVariable *Var);
@@ -679,6 +682,10 @@ public:
 
   /// Returns the Dwarf Version.
   unsigned getDwarfVersion() const { return DwarfVersion; }
+
+  /// Find the MDNode for the given type reference.
+  MDNode *resolve(DITypeRef TRef) const;
+
 };
 } // End of namespace llvm