Debugger: Handle DW_AT_signature.

- Per DWARF4's specification, if a type's complete definition is
  contained in a .debug_types unit, it should be referenced via the
  DW_AT_signature attribute. 4.8 now actually does this rather than
  setting e.g. DW_AT_attribute_origin to a signature ref, and
  consequently we weren't finding said reference any more.

Gets .debug_types section support working again.

src/apps/debugger/dwarf/DebugInfoEntries.cpp

@@ -314,6 +314,7 @@ DIEDeclaredType::DIEDeclaredType()
 	:
 	fDescription(NULL),
 	fAbstractOrigin(NULL),
+	fSignatureType(NULL),
 	fAccessibility(0),
 	fDeclaration(false)
 {
@@ -334,6 +335,13 @@ DIEDeclaredType::AbstractOrigin() const
 }
 
 
+DebugInfoEntry*
+DIEDeclaredType::SignatureType() const
+{
+	return fSignatureType;
+}
+
+
 bool
 DIEDeclaredType::IsDeclaration() const
 {
@@ -377,6 +385,15 @@ DIEDeclaredType::AddAttribute_abstract_origin(uint16 attributeName,
 }
 
 
+status_t
+DIEDeclaredType::AddAttribute_signature(uint16 attributeName,
+	const AttributeValue& value)
+{
+	fSignatureType = value.reference;
+	return B_OK;
+}
+
+
 DeclarationLocation*
 DIEDeclaredType::GetDeclarationLocation()
 {

src/apps/debugger/dwarf/DebugInfoEntries.h

@@ -281,6 +281,8 @@ public:
 	virtual	const char*			Description() const;
 	virtual	DebugInfoEntry*		AbstractOrigin() const;
 
+	virtual DebugInfoEntry*		SignatureType() const;
+
 	virtual	bool				IsDeclaration() const;
 
 	virtual	status_t			AddAttribute_accessibility(uint16 attributeName,
@@ -296,6 +298,8 @@ public:
 									uint16 attributeName,
 									const AttributeValue& value);
 										// TODO: !interface
+	virtual	status_t			AddAttribute_signature(uint16 attributeName,
+									const AttributeValue& value);
 
 // TODO:
 // DW_AT_visibility			// !interface
@@ -307,6 +311,7 @@ protected:
 			const char*			fDescription;
 			DeclarationLocation	fDeclarationLocation;
 			DebugInfoEntry*		fAbstractOrigin;
+			DebugInfoEntry*		fSignatureType;
 			uint8				fAccessibility;
 			bool				fDeclaration;
 };

src/apps/debugger/dwarf/DebugInfoEntry.cpp

@@ -1,6 +1,6 @@
 /*
  * Copyright 2009, Ingo Weinhold, ingo_weinhold@gmx.de.
- * Copyright 2013, Rene Gollent, rene@gollent.com.
+ * Copyright 2013-2014, Rene Gollent, rene@gollent.com.
  * Distributed under the terms of the MIT License.
  */
 
@@ -95,6 +95,13 @@ DebugInfoEntry::AbstractOrigin() const
 }
 
 
+DebugInfoEntry*
+DebugInfoEntry::SignatureType() const
+{
+	return NULL;
+}
+
+
 LocationDescription*
 DebugInfoEntry::GetLocationDescription()
 {

src/apps/debugger/dwarf/DebugInfoEntry.h

@@ -1,6 +1,6 @@
 /*
  * Copyright 2009, Ingo Weinhold, ingo_weinhold@gmx.de.
- * Copyright 2013, Rene Gollent, rene@gollent.com.
+ * Copyright 2013-2014, Rene Gollent, rene@gollent.com.
  * Distributed under the terms of the MIT License.
  */
 #ifndef DEBUG_INFO_ENTRY_H
@@ -61,6 +61,7 @@ public:
 	virtual	const char*			Description() const;
 	virtual	DebugInfoEntry*		Specification() const;
 	virtual	DebugInfoEntry*		AbstractOrigin() const;
+	virtual	DebugInfoEntry*		SignatureType() const;
 	virtual	LocationDescription* GetLocationDescription();
 
 			bool				GetDeclarationFile(uint32& _file) const;

src/apps/debugger/dwarf/DwarfUtils.h

@@ -1,6 +1,6 @@
 /*
  * Copyright 2009, Ingo Weinhold, ingo_weinhold@gmx.de.
- * Copyright 2013, Rene Gollent, rene@gollent.com.
+ * Copyright 2013-2014, Rene Gollent, rene@gollent.com.
  * Distributed under the terms of the MIT License.
  */
 #ifndef DWARF_UTILS_H
@@ -61,6 +61,14 @@ DwarfUtils::GetDIEByPredicate(EntryType* entry, const Predicate& predicate)
 			return entry;
 	}
 
+	// try the type unit signature
+	if (EntryType* signature = dynamic_cast<EntryType*>(
+			entry->SignatureType())) {
+		entry = signature;
+		if (predicate(entry))
+			return entry;
+	}
+
 	return NULL;
 }