1 files changed, 38 insertions, 6 deletions

diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DIERef.h b/lldb/source/Plugins/SymbolFile/DWARF/DIERef.h
index e7843da404a..476539bf840 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DIERef.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DIERef.h
@@ -10,19 +10,51 @@
 #define SymbolFileDWARF_DIERef_h_
 
 #include "lldb/Core/dwarf.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/Support/FormatProviders.h"
 #include <vector>
 
-struct DIERef {
+/// Identifies a DWARF debug info entry within a given Module. It contains three
+/// "coordinates":
+/// - section: identifies the section of the debug info entry: debug_info or
+///   debug_types
+/// - unit_offset: the offset of the unit containing the debug info entry. For
+///   regular (unsplit) units, this field is optional, as the die_offset is
+///   enough to uniquely identify the containing unit. For split units, this
+///   field must contain the offset of the skeleton unit in the main object
+///   file.
+/// - die_offset: The offset of te debug info entry as an absolute offset from
+///   the beginning of the section specified in the section field.
+class DIERef {
+public:
   enum Section : uint8_t { DebugInfo, DebugTypes };
 
-  DIERef(Section s, dw_offset_t c, dw_offset_t d)
-      : section(s), cu_offset(c), die_offset(d) {}
+  DIERef(Section s, llvm::Optional<dw_offset_t> u, dw_offset_t d)
+      : m_section(s), m_unit_offset(u.getValueOr(DW_INVALID_OFFSET)),
+        m_die_offset(d) {}
 
-  Section section;
-  dw_offset_t cu_offset;
-  dw_offset_t die_offset;
+  Section section() const { return static_cast<Section>(m_section); }
+
+  llvm::Optional<dw_offset_t> unit_offset() const {
+    if (m_unit_offset != DW_INVALID_OFFSET)
+      return m_unit_offset;
+    return llvm::None;
+  }
+
+  dw_offset_t die_offset() const { return m_die_offset; }
+
+private:
+  unsigned m_section : 1;
+  dw_offset_t m_unit_offset;
+  dw_offset_t m_die_offset;
 };
 
 typedef std::vector<DIERef> DIEArray;
 
+namespace llvm {
+template<> struct format_provider<DIERef> {
+  static void format(const DIERef &ref, raw_ostream &OS, StringRef Style);
+};
+} // namespace llvm
+
 #endif // SymbolFileDWARF_DIERef_h_