Debugger: DwarfFile: Fix DWARF4 signature handling.

Depending on how the type unit was actually set up hierarchically,
we sometimes ended up with the unit set to the wrong actual type
object. Instead, we now simply let the unit parse, and then look up
the entry by the offset specified in the header after all is said
and done. Fixes class/struct objects sometimes winding up resolving
to one of their members instead.

Some problems still remain with resolving variable values for such
types though, needs further investigation.

src/apps/debugger/dwarf/DebugInfoEntries.cpp

@@ -2549,16 +2549,6 @@ DIETypeUnit::Tag() const
 }
 
 
-status_t
-DIETypeUnit::AddChild(DebugInfoEntry* child)
-{
-	if (child->IsType())
-		fType = dynamic_cast<DIEType*>(child);
-
-	return B_OK;
-}
-
-
 status_t
 DIETypeUnit::AddAttribute_language(uint16 attributeName,
 	const AttributeValue& value)

src/apps/debugger/dwarf/DebugInfoEntries.h

@@ -1614,16 +1614,11 @@ public:
 
 			uint16				Language() const	{ return fLanguage; }
 
-	virtual	status_t			AddChild(DebugInfoEntry* child);
-
 	virtual	status_t			AddAttribute_language(uint16 attributeName,
 									const AttributeValue& value);
-	inline	DIEType*			GetType() const { return fType; }
-
 
 private:
 			uint16				fLanguage;
-			DIEType*			fType;
 };
 
 

src/apps/debugger/dwarf/DwarfFile.cpp

@@ -1142,6 +1142,13 @@ DwarfFile::_ParseTypeUnit(TypeUnit* unit)
 	}
 
 	unit->SetUnitEntry(unitEntry);
+	DebugInfoEntry* typeEntry = unit->EntryForOffset(unit->TypeOffset());
+	if (typeEntry == NULL) {
+		WARNING("No type found for type unit %p at specified offset %"
+			B_PRId64 ".\n", unit, unit->TypeOffset());
+		return B_BAD_DATA;
+	}
+	unit->SetTypeEntry(typeEntry);
 
 	TRACE_DIE_ONLY(
 		TRACE_DIE("remaining bytes in unit: %" B_PRIdOFF "\n",
@@ -2591,6 +2598,7 @@ DwarfFile::_ResolveReference(BaseUnit* unit, uint64 offset,
 		}
 		case dwarf_reference_type_signature:
 		{
+			TRACE_DIE("Resolving signature %#" B_PRIx64 "\n", offset);
 			TypeUnitTableEntry* entry = fTypeUnits.Lookup(offset);
 			if (entry != NULL && entry->unit != NULL)
 				return entry->unit->TypeEntry();

src/apps/debugger/dwarf/TypeUnit.cpp

@@ -16,6 +16,7 @@ TypeUnit::TypeUnit(off_t headerOffset, off_t contentOffset,
 	BaseUnit(headerOffset, contentOffset, totalSize, abbreviationOffset,
 		addressSize, isDwarf64),
 	fUnitEntry(NULL),
+	fTypeEntry(NULL),
 	fSignature(signature),
 	fTypeOffset(typeOffset)
 {
@@ -37,10 +38,14 @@ TypeUnit::SetUnitEntry(DIETypeUnit* entry)
 DebugInfoEntry*
 TypeUnit::TypeEntry() const
 {
-	if (fUnitEntry != NULL)
-		return fUnitEntry->GetType();
+	return fTypeEntry;
+}
 
-	return NULL;
+
+void
+TypeUnit::SetTypeEntry(DebugInfoEntry* entry)
+{
+	fTypeEntry = entry;
 }
 
 

src/apps/debugger/dwarf/TypeUnit.h

@@ -36,11 +36,13 @@ public:
 			void				SetUnitEntry(DIETypeUnit* entry);
 
 			DebugInfoEntry*		TypeEntry() const;
+			void				SetTypeEntry(DebugInfoEntry* entry);
 
 	virtual	dwarf_unit_kind		Kind() const;
 
 private:
 			DIETypeUnit*		fUnitEntry;
+			DebugInfoEntry*		fTypeEntry;
 			uint64				fSignature;
 			off_t				fTypeOffset;
 };