Index: lldb/trunk/lit/SymbolFile/DWARF/find-variable-file.cpp
===================================================================
--- lldb/trunk/lit/SymbolFile/DWARF/find-variable-file.cpp
+++ lldb/trunk/lit/SymbolFile/DWARF/find-variable-file.cpp
@@ -8,6 +8,16 @@
 // RUN: lldb-test symbols --file=find-variable-file-2.cpp --find=variable %t | \
 // RUN:   FileCheck --check-prefix=TWO %s
 
+// Run the same test with split-dwarf. This is interesting because the two
+// split compile units will have the same offset (0).
+// RUN: %clang -g -c -o %t-1.o --target=x86_64-pc-linux -gsplit-dwarf %s
+// RUN: %clang -g -c -o %t-2.o --target=x86_64-pc-linux -gsplit-dwarf %S/Inputs/find-variable-file-2.cpp
+// RUN: ld.lld %t-1.o %t-2.o -o %t
+// RUN: lldb-test symbols --file=find-variable-file.cpp --find=variable %t | \
+// RUN:   FileCheck --check-prefix=ONE %s
+// RUN: lldb-test symbols --file=find-variable-file-2.cpp --find=variable %t | \
+// RUN:   FileCheck --check-prefix=TWO %s
+
 // RUN: %clang -g -c -o %t-1.o --target=x86_64-pc-linux -mllvm -accel-tables=Dwarf %s
 // RUN: %clang -g -c -o %t-2.o --target=x86_64-pc-linux -mllvm -accel-tables=Dwarf %S/Inputs/find-variable-file-2.cpp
 // RUN: ld.lld %t-1.o %t-2.o -o %t
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/AppleDWARFIndex.h
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/AppleDWARFIndex.h
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/AppleDWARFIndex.h
@@ -42,7 +42,7 @@
   void GetTypes(ConstString name, DIEArray &offsets) override;
   void GetTypes(const DWARFDeclContext &context, DIEArray &offsets) override;
   void GetNamespaces(ConstString name, DIEArray &offsets) override;
-  void GetFunctions(ConstString name, DWARFDebugInfo &info,
+  void GetFunctions(ConstString name, SymbolFileDWARF &dwarf,
                     const CompilerDeclContext &parent_decl_ctx,
                     uint32_t name_type_mask,
                     std::vector<DWARFDIE> &dies) override;
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/AppleDWARFIndex.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/AppleDWARFIndex.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/AppleDWARFIndex.cpp
@@ -7,7 +7,6 @@
 //===----------------------------------------------------------------------===//
 
 #include "Plugins/SymbolFile/DWARF/AppleDWARFIndex.h"
-#include "Plugins/SymbolFile/DWARF/DWARFDebugInfo.h"
 #include "Plugins/SymbolFile/DWARF/DWARFDeclContext.h"
 #include "Plugins/SymbolFile/DWARF/DWARFUnit.h"
 #include "Plugins/SymbolFile/DWARF/LogChannelDWARF.h"
@@ -133,14 +132,14 @@
     m_apple_namespaces_up->FindByName(name.GetStringRef(), offsets);
 }
 
-void AppleDWARFIndex::GetFunctions(ConstString name, DWARFDebugInfo &info,
+void AppleDWARFIndex::GetFunctions(ConstString name, SymbolFileDWARF &dwarf,
                                    const CompilerDeclContext &parent_decl_ctx,
                                    uint32_t name_type_mask,
                                    std::vector<DWARFDIE> &dies) {
   DIEArray offsets;
   m_apple_names_up->FindByName(name.GetStringRef(), offsets);
   for (const DIERef &die_ref : offsets) {
-    ProcessFunctionDIE(name.GetStringRef(), die_ref, info, parent_decl_ctx,
+    ProcessFunctionDIE(name.GetStringRef(), die_ref, dwarf, parent_decl_ctx,
                        name_type_mask, dies);
   }
 }
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DIERef.h
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DIERef.h
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DIERef.h
@@ -12,42 +12,45 @@
 #include "lldb/Core/dwarf.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/Support/FormatProviders.h"
+#include <cassert>
 #include <vector>
 
 /// 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
+/// - dwo_num: identifies the dwo file in the Module. If this field is not set,
+///   the DIERef references the main file.
+/// - section: identifies the section of the debug info entry in the given file:
+///   debug_info or debug_types.
+/// - die_offset: The offset of the 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, 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() const { return static_cast<Section>(m_section); }
+  DIERef(llvm::Optional<uint32_t> dwo_num, Section section,
+         dw_offset_t die_offset)
+      : m_dwo_num(dwo_num.getValueOr(0)), m_dwo_num_valid(bool(dwo_num)),
+        m_section(section), m_die_offset(die_offset) {
+    assert(this->dwo_num() == dwo_num && "Dwo number out of range?");
+  }
 
-  llvm::Optional<dw_offset_t> unit_offset() const {
-    if (m_unit_offset != DW_INVALID_OFFSET)
-      return m_unit_offset;
+  llvm::Optional<uint32_t> dwo_num() const {
+    if (m_dwo_num_valid)
+      return m_dwo_num;
     return llvm::None;
   }
 
+  Section section() const { return static_cast<Section>(m_section); }
+
   dw_offset_t die_offset() const { return m_die_offset; }
 
 private:
-  unsigned m_section : 1;
-  dw_offset_t m_unit_offset;
+  uint32_t m_dwo_num : 30;
+  uint32_t m_dwo_num_valid : 1;
+  uint32_t m_section : 1;
   dw_offset_t m_die_offset;
 };
+static_assert(sizeof(DIERef) == 8, "");
 
 typedef std::vector<DIERef> DIEArray;
 
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DIERef.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DIERef.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DIERef.cpp
@@ -11,8 +11,8 @@
 
 void llvm::format_provider<DIERef>::format(const DIERef &ref, raw_ostream &OS,
                                            StringRef Style) {
+  if (ref.dwo_num())
+    OS << format_hex_no_prefix(*ref.dwo_num(), 8) << "/";
   OS << (ref.section() == DIERef::DebugInfo ? "INFO" : "TYPE");
-  if (ref.unit_offset())
-    OS << "/" << format_hex_no_prefix(*ref.unit_offset(), 8);
   OS << "/" << format_hex_no_prefix(ref.die_offset(), 8);
 }
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFBaseDIE.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFBaseDIE.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFBaseDIE.cpp
@@ -21,10 +21,8 @@
   if (!IsValid())
     return llvm::None;
 
-  dw_offset_t cu_offset = m_cu->GetOffset();
-  if (m_cu->GetBaseObjOffset() != DW_INVALID_OFFSET)
-    cu_offset = m_cu->GetBaseObjOffset();
-  return DIERef(m_cu->GetDebugSection(), cu_offset, m_die->GetOffset());
+  return DIERef(m_cu->GetSymbolFileDWARF().GetDwoNum(), m_cu->GetDebugSection(),
+                m_die->GetOffset());
 }
 
 dw_tag_t DWARFBaseDIE::Tag() const {
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDIE.cpp
@@ -151,9 +151,9 @@
         if (cu->ContainsDIEOffset(block_die->GetOffset()))
           return DWARFDIE(cu, block_die);
         else
-          return DWARFDIE(dwarf->DebugInfo()->GetUnit(
-                              DIERef(cu->GetDebugSection(), cu->GetOffset(),
-                                     block_die->GetOffset())),
+          return DWARFDIE(dwarf->DebugInfo()->GetUnit(DIERef(
+                              cu->GetSymbolFileDWARF().GetDwoNum(),
+                              cu->GetDebugSection(), block_die->GetOffset())),
                           block_die);
       }
     }
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDebugInfo.cpp
@@ -149,8 +149,6 @@
 }
 
 DWARFUnit *DWARFDebugInfo::GetUnit(const DIERef &die_ref) {
-  if (die_ref.unit_offset())
-    return GetUnitAtOffset(die_ref.section(), *die_ref.unit_offset());
   return GetUnitContainingDIEOffset(die_ref.section(), die_ref.die_offset());
 }
 
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFDebugInfoEntry.cpp
@@ -226,12 +226,6 @@
     DWARFRangeList &ranges, int &decl_file, int &decl_line, int &decl_column,
     int &call_file, int &call_line, int &call_column,
     DWARFExpression *frame_base) const {
-  SymbolFileDWARFDwo *dwo_symbol_file = cu->GetDwoSymbolFile();
-  if (dwo_symbol_file)
-    return GetDIENamesAndRanges(
-        dwo_symbol_file->GetCompileUnit(), name, mangled, ranges, decl_file,
-        decl_line, decl_column, call_file, call_line, call_column, frame_base);
-
   dw_addr_t lo_pc = LLDB_INVALID_ADDRESS;
   dw_addr_t hi_pc = LLDB_INVALID_ADDRESS;
   std::vector<DWARFDIE> dies;
@@ -611,16 +605,7 @@
     const DWARFUnit *cu, const dw_attr_t attr, DWARFFormValue &form_value,
     dw_offset_t *end_attr_offset_ptr,
     bool check_specification_or_abstract_origin) const {
-  SymbolFileDWARFDwo *dwo_symbol_file = cu->GetDwoSymbolFile();
-  if (dwo_symbol_file && m_tag != DW_TAG_compile_unit &&
-                         m_tag != DW_TAG_partial_unit)
-    return GetAttributeValue(dwo_symbol_file->GetCompileUnit(), attr,
-                             form_value, end_attr_offset_ptr,
-                             check_specification_or_abstract_origin);
-
-  auto abbrevDecl = GetAbbreviationDeclarationPtr(cu);
-
-  if (abbrevDecl) {
+  if (auto *abbrevDecl = GetAbbreviationDeclarationPtr(cu)) {
     uint32_t attr_idx = abbrevDecl->FindAttributeIndex(attr);
 
     if (attr_idx != DW_INVALID_INDEX) {
@@ -665,6 +650,10 @@
     }
   }
 
+  // If we're a unit DIE, also check the attributes of the dwo unit (if any).
+  if (GetParent())
+    return 0;
+  SymbolFileDWARFDwo *dwo_symbol_file = cu->GetDwoSymbolFile();
   if (!dwo_symbol_file)
     return 0;
 
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFIndex.h
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFIndex.h
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFIndex.h
@@ -13,7 +13,6 @@
 #include "Plugins/SymbolFile/DWARF/DWARFDIE.h"
 #include "Plugins/SymbolFile/DWARF/DWARFFormValue.h"
 
-class DWARFDebugInfo;
 class DWARFDeclContext;
 class DWARFDIE;
 
@@ -40,7 +39,7 @@
   virtual void GetTypes(ConstString name, DIEArray &offsets) = 0;
   virtual void GetTypes(const DWARFDeclContext &context, DIEArray &offsets) = 0;
   virtual void GetNamespaces(ConstString name, DIEArray &offsets) = 0;
-  virtual void GetFunctions(ConstString name, DWARFDebugInfo &info,
+  virtual void GetFunctions(ConstString name, SymbolFileDWARF &dwarf,
                             const CompilerDeclContext &parent_decl_ctx,
                             uint32_t name_type_mask,
                             std::vector<DWARFDIE> &dies) = 0;
@@ -58,7 +57,7 @@
   /// "parent_decl_ctx" and "name_type_mask", it is inserted into the "dies"
   /// vector.
   void ProcessFunctionDIE(llvm::StringRef name, DIERef ref,
-                          DWARFDebugInfo &info,
+                          SymbolFileDWARF &dwarf,
                           const CompilerDeclContext &parent_decl_ctx,
                           uint32_t name_type_mask, std::vector<DWARFDIE> &dies);
 };
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFIndex.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFIndex.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFIndex.cpp
@@ -7,10 +7,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "Plugins/SymbolFile/DWARF/DWARFIndex.h"
-#include "Plugins/SymbolFile/DWARF/DWARFDIE.h"
-#include "Plugins/SymbolFile/DWARF/DWARFDebugInfo.h"
-
 #include "Plugins/Language/ObjC/ObjCLanguage.h"
+#include "Plugins/SymbolFile/DWARF/DWARFDIE.h"
+#include "Plugins/SymbolFile/DWARF/SymbolFileDWARF.h"
 
 using namespace lldb_private;
 using namespace lldb;
@@ -18,11 +17,11 @@
 DWARFIndex::~DWARFIndex() = default;
 
 void DWARFIndex::ProcessFunctionDIE(llvm::StringRef name, DIERef ref,
-                                    DWARFDebugInfo &info,
+                                    SymbolFileDWARF &dwarf,
                                     const CompilerDeclContext &parent_decl_ctx,
                                     uint32_t name_type_mask,
                                     std::vector<DWARFDIE> &dies) {
-  DWARFDIE die = info.GetDIE(ref);
+  DWARFDIE die = dwarf.GetDIE(ref);
   if (!die) {
     ReportInvalidDIERef(ref, name);
     return;
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
@@ -148,7 +148,6 @@
   dw_addr_t GetStrOffsetsBase() const { return m_str_offsets_base; }
   void SetAddrBase(dw_addr_t addr_base);
   void SetRangesBase(dw_addr_t ranges_base);
-  void SetBaseObjOffset(dw_offset_t base_obj_offset);
   void SetStrOffsetsBase(dw_offset_t str_offsets_base);
   virtual void BuildAddressRangeTable(DWARFDebugAranges *debug_aranges) = 0;
 
@@ -166,6 +165,8 @@
 
   DWARFDIE GetDIE(dw_offset_t die_offset);
 
+  DWARFUnit &GetNonSkeletonUnit();
+
   static uint8_t GetAddressByteSize(const DWARFUnit *cu);
 
   static uint8_t GetDefaultAddressSize();
@@ -203,8 +204,6 @@
 
   SymbolFileDWARFDwo *GetDwoSymbolFile() const;
 
-  dw_offset_t GetBaseObjOffset() const;
-
   die_iterator_range dies() {
     ExtractDIEsIfNeeded();
     return die_iterator_range(m_die_array.begin(), m_die_array.end());
@@ -284,9 +283,6 @@
   llvm::Optional<lldb_private::FileSpec> m_file_spec;
   dw_addr_t m_addr_base = 0;   // Value of DW_AT_addr_base
   dw_addr_t m_ranges_base = 0; // Value of DW_AT_ranges_base
-  // If this is a dwo compile unit this is the offset of the base compile unit
-  // in the main object file
-  dw_offset_t m_base_obj_offset = DW_INVALID_OFFSET;
 
   /// Value of DW_AT_stmt_list.
   dw_offset_t m_line_table_offset = DW_INVALID_OFFSET;
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -363,7 +363,6 @@
   else if (gnu_ranges_base)
     dwo_cu->SetRangesBase(*gnu_ranges_base);
 
-  dwo_cu->SetBaseObjOffset(GetOffset());
   SetDwoStrOffsetsBase(dwo_cu);
 }
 
@@ -419,10 +418,6 @@
   m_ranges_base = ranges_base;
 }
 
-void DWARFUnit::SetBaseObjOffset(dw_offset_t base_obj_offset) {
-  m_base_obj_offset = base_obj_offset;
-}
-
 void DWARFUnit::SetStrOffsetsBase(dw_offset_t str_offsets_base) {
   m_str_offsets_base = str_offsets_base;
 }
@@ -480,6 +475,12 @@
   return DWARFDIE(); // Not found
 }
 
+DWARFUnit &DWARFUnit::GetNonSkeletonUnit() {
+  if (SymbolFileDWARFDwo *dwo = GetDwoSymbolFile())
+    return *dwo->GetCompileUnit();
+  return *this;
+}
+
 uint8_t DWARFUnit::GetAddressByteSize(const DWARFUnit *cu) {
   if (cu)
     return cu->GetAddressByteSize();
@@ -719,8 +720,6 @@
   return m_dwo_symbol_file.get();
 }
 
-dw_offset_t DWARFUnit::GetBaseObjOffset() const { return m_base_obj_offset; }
-
 const DWARFDebugAranges &DWARFUnit::GetFunctionAranges() {
   if (m_func_aranges_up == nullptr) {
     m_func_aranges_up.reset(new DWARFDebugAranges());
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.h
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.h
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.h
@@ -34,7 +34,7 @@
   void GetTypes(ConstString name, DIEArray &offsets) override;
   void GetTypes(const DWARFDeclContext &context, DIEArray &offsets) override;
   void GetNamespaces(ConstString name, DIEArray &offsets) override;
-  void GetFunctions(ConstString name, DWARFDebugInfo &info,
+  void GetFunctions(ConstString name, SymbolFileDWARF &dwarf,
                     const CompilerDeclContext &parent_decl_ctx,
                     uint32_t name_type_mask,
                     std::vector<DWARFDIE> &dies) override;
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.cpp
@@ -64,10 +64,11 @@
   // GetDwoSymbolFile to call this automatically because of mutual recursion
   // between this and DWARFDebugInfoEntry::GetAttributeValue.
   cu->ExtractUnitDIEIfNeeded();
-  uint64_t die_bias = cu->GetDwoSymbolFile() ? 0 : *cu_offset;
+  cu = &cu->GetNonSkeletonUnit();
 
   if (llvm::Optional<uint64_t> die_offset = entry.getDIEUnitOffset())
-    return DIERef(DIERef::Section::DebugInfo, *cu_offset, die_bias + *die_offset);
+    return DIERef(cu->GetSymbolFileDWARF().GetDwoNum(),
+                  DIERef::Section::DebugInfo, cu->GetOffset() + *die_offset);
 
   return llvm::None;
 }
@@ -165,8 +166,7 @@
     if (!ref)
       continue;
 
-    DWARFUnit *cu = m_debug_info.GetUnitAtOffset(DIERef::Section::DebugInfo,
-                                                 *ref->unit_offset());
+    DWARFUnit *cu = m_debug_info.GetUnit(*ref);
     if (!cu || !cu->Supports_DW_AT_APPLE_objc_complete_type()) {
       incomplete_types.push_back(*ref);
       continue;
@@ -222,12 +222,12 @@
 }
 
 void DebugNamesDWARFIndex::GetFunctions(
-    ConstString name, DWARFDebugInfo &info,
+    ConstString name, SymbolFileDWARF &dwarf,
     const CompilerDeclContext &parent_decl_ctx, uint32_t name_type_mask,
     std::vector<DWARFDIE> &dies) {
 
   std::vector<DWARFDIE> v;
-  m_fallback.GetFunctions(name, info, parent_decl_ctx, name_type_mask, v);
+  m_fallback.GetFunctions(name, dwarf, parent_decl_ctx, name_type_mask, v);
 
   for (const DebugNames::Entry &entry :
        m_debug_names_up->equal_range(name.GetStringRef())) {
@@ -236,7 +236,7 @@
       continue;
 
     if (llvm::Optional<DIERef> ref = ToDIERef(entry))
-      ProcessFunctionDIE(name.GetStringRef(), *ref, info, parent_decl_ctx,
+      ProcessFunctionDIE(name.GetStringRef(), *ref, dwarf, parent_decl_ctx,
                          name_type_mask, v);
   }
 
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/HashedNameToDIE.h
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/HashedNameToDIE.h
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/HashedNameToDIE.h
@@ -61,7 +61,7 @@
     DIEInfo(dw_offset_t o, dw_tag_t t, uint32_t f, uint32_t h);
 
     explicit operator DIERef() const {
-      return DIERef(DIERef::Section::DebugInfo, llvm::None, die_offset);
+      return DIERef(llvm::None, DIERef::Section::DebugInfo, die_offset);
     }
   };
 
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.h
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.h
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.h
@@ -13,6 +13,8 @@
 #include "Plugins/SymbolFile/DWARF/NameToDIE.h"
 #include "llvm/ADT/DenseSet.h"
 
+class DWARFDebugInfo;
+
 namespace lldb_private {
 class ManualDWARFIndex : public DWARFIndex {
 public:
@@ -26,14 +28,14 @@
   void GetGlobalVariables(ConstString basename, DIEArray &offsets) override;
   void GetGlobalVariables(const RegularExpression &regex,
                           DIEArray &offsets) override;
-  void GetGlobalVariables(const DWARFUnit &cu, DIEArray &offsets) override;
+  void GetGlobalVariables(const DWARFUnit &unit, DIEArray &offsets) override;
   void GetObjCMethods(ConstString class_name, DIEArray &offsets) override;
   void GetCompleteObjCClass(ConstString class_name, bool must_be_implementation,
                             DIEArray &offsets) override;
   void GetTypes(ConstString name, DIEArray &offsets) override;
   void GetTypes(const DWARFDeclContext &context, DIEArray &offsets) override;
   void GetNamespaces(ConstString name, DIEArray &offsets) override;
-  void GetFunctions(ConstString name, DWARFDebugInfo &info,
+  void GetFunctions(ConstString name, SymbolFileDWARF &dwarf,
                     const CompilerDeclContext &parent_decl_ctx,
                     uint32_t name_type_mask,
                     std::vector<DWARFDIE> &dies) override;
@@ -56,9 +58,9 @@
   void Index();
   void IndexUnit(DWARFUnit &unit, IndexSet &set);
 
-  static void
-  IndexUnitImpl(DWARFUnit &unit, const lldb::LanguageType cu_language,
-                const dw_offset_t cu_offset, IndexSet &set);
+  static void IndexUnitImpl(DWARFUnit &unit,
+                            const lldb::LanguageType cu_language,
+                            IndexSet &set);
 
   /// Non-null value means we haven't built the index yet.
   DWARFDebugInfo *m_debug_info;
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
@@ -102,18 +102,17 @@
 
   const LanguageType cu_language = unit.GetLanguageType();
 
-  IndexUnitImpl(unit, cu_language, unit.GetOffset(), set);
+  IndexUnitImpl(unit, cu_language, set);
 
   SymbolFileDWARFDwo *dwo_symbol_file = unit.GetDwoSymbolFile();
   if (dwo_symbol_file && dwo_symbol_file->GetCompileUnit()) {
-    IndexUnitImpl(*dwo_symbol_file->GetCompileUnit(), cu_language,
-                  unit.GetOffset(), set);
+    IndexUnitImpl(*dwo_symbol_file->GetCompileUnit(), cu_language, set);
   }
 }
 
-void ManualDWARFIndex::IndexUnitImpl(
-    DWARFUnit &unit, const LanguageType cu_language,
-    const dw_offset_t cu_offset, IndexSet &set) {
+void ManualDWARFIndex::IndexUnitImpl(DWARFUnit &unit,
+                                     const LanguageType cu_language,
+                                     IndexSet &set) {
   for (const DWARFDebugInfoEntry &die : unit.dies()) {
     const dw_tag_t tag = die.Tag();
 
@@ -243,7 +242,7 @@
       }
     }
 
-    DIERef ref(unit.GetDebugSection(), cu_offset, die.GetOffset());
+    DIERef ref = *DWARFDIE(&unit, &die).GetDIERef();
     switch (tag) {
     case DW_TAG_inlined_subroutine:
     case DW_TAG_subprogram:
@@ -358,10 +357,10 @@
   m_set.globals.Find(regex, offsets);
 }
 
-void ManualDWARFIndex::GetGlobalVariables(const DWARFUnit &cu,
+void ManualDWARFIndex::GetGlobalVariables(const DWARFUnit &unit,
                                           DIEArray &offsets) {
   Index();
-  m_set.globals.FindAllEntriesForCompileUnit(cu.GetOffset(), offsets);
+  m_set.globals.FindAllEntriesForUnit(unit, offsets);
 }
 
 void ManualDWARFIndex::GetObjCMethods(ConstString class_name,
@@ -393,7 +392,7 @@
   m_set.namespaces.Find(name, offsets);
 }
 
-void ManualDWARFIndex::GetFunctions(ConstString name, DWARFDebugInfo &info,
+void ManualDWARFIndex::GetFunctions(ConstString name, SymbolFileDWARF &dwarf,
                                     const CompilerDeclContext &parent_decl_ctx,
                                     uint32_t name_type_mask,
                                     std::vector<DWARFDIE> &dies) {
@@ -405,7 +404,7 @@
     m_set.function_methods.Find(name, offsets);
     m_set.function_fullnames.Find(name, offsets);
     for (const DIERef &die_ref: offsets) {
-      DWARFDIE die = info.GetDIE(die_ref);
+      DWARFDIE die = dwarf.GetDIE(die_ref);
       if (!die)
         continue;
       if (SymbolFileDWARF::DIEInDeclContext(&parent_decl_ctx, die))
@@ -416,7 +415,7 @@
     DIEArray offsets;
     m_set.function_basenames.Find(name, offsets);
     for (const DIERef &die_ref: offsets) {
-      DWARFDIE die = info.GetDIE(die_ref);
+      DWARFDIE die = dwarf.GetDIE(die_ref);
       if (!die)
         continue;
       if (SymbolFileDWARF::DIEInDeclContext(&parent_decl_ctx, die))
@@ -429,7 +428,7 @@
     DIEArray offsets;
     m_set.function_methods.Find(name, offsets);
     for (const DIERef &die_ref: offsets) {
-      if (DWARFDIE die = info.GetDIE(die_ref))
+      if (DWARFDIE die = dwarf.GetDIE(die_ref))
         dies.push_back(die);
     }
   }
@@ -439,7 +438,7 @@
     DIEArray offsets;
     m_set.function_selectors.Find(name, offsets);
     for (const DIERef &die_ref: offsets) {
-      if (DWARFDIE die = info.GetDIE(die_ref))
+      if (DWARFDIE die = dwarf.GetDIE(die_ref))
         dies.push_back(die);
     }
   }
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/NameToDIE.h
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/NameToDIE.h
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/NameToDIE.h
@@ -16,7 +16,7 @@
 #include "lldb/Core/dwarf.h"
 #include "lldb/lldb-defines.h"
 
-class SymbolFileDWARF;
+class DWARFUnit;
 
 class NameToDIE {
 public:
@@ -38,8 +38,8 @@
   size_t Find(const lldb_private::RegularExpression &regex,
               DIEArray &info_array) const;
 
-  size_t FindAllEntriesForCompileUnit(dw_offset_t cu_offset,
-                                      DIEArray &info_array) const;
+  size_t FindAllEntriesForUnit(const DWARFUnit &unit,
+                               DIEArray &info_array) const;
 
   void
   ForEach(std::function<bool(lldb_private::ConstString name,
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/NameToDIE.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/NameToDIE.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/NameToDIE.cpp
@@ -7,16 +7,13 @@
 //===----------------------------------------------------------------------===//
 
 #include "NameToDIE.h"
+#include "DWARFUnit.h"
 #include "lldb/Symbol/ObjectFile.h"
 #include "lldb/Utility/ConstString.h"
 #include "lldb/Utility/RegularExpression.h"
 #include "lldb/Utility/Stream.h"
 #include "lldb/Utility/StreamString.h"
 
-#include "DWARFDebugInfo.h"
-#include "DWARFDebugInfoEntry.h"
-#include "SymbolFileDWARF.h"
-
 using namespace lldb;
 using namespace lldb_private;
 
@@ -26,7 +23,6 @@
 }
 
 void NameToDIE::Insert(ConstString name, const DIERef &die_ref) {
-  assert(die_ref.unit_offset().hasValue());
   m_map.Append(name, die_ref);
 }
 
@@ -39,13 +35,16 @@
   return m_map.GetValues(regex, info_array);
 }
 
-size_t NameToDIE::FindAllEntriesForCompileUnit(dw_offset_t cu_offset,
-                                               DIEArray &info_array) const {
+size_t NameToDIE::FindAllEntriesForUnit(const DWARFUnit &unit,
+                                        DIEArray &info_array) const {
   const size_t initial_size = info_array.size();
   const uint32_t size = m_map.GetSize();
   for (uint32_t i = 0; i < size; ++i) {
     const DIERef &die_ref = m_map.GetValueAtIndexUnchecked(i);
-    if (cu_offset == *die_ref.unit_offset())
+    if (unit.GetSymbolFileDWARF().GetDwoNum() == die_ref.dwo_num() &&
+        unit.GetDebugSection() == die_ref.section() &&
+        unit.GetOffset() <= die_ref.die_offset() &&
+        die_ref.die_offset() < unit.GetNextUnitOffset())
       info_array.push_back(die_ref);
   }
   return info_array.size() - initial_size;
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -275,11 +275,7 @@
     return ref ? GetUID(*ref) : LLDB_INVALID_UID;
   }
 
-  lldb::user_id_t GetUID(const DIERef &ref) {
-    return GetID() | ref.die_offset() |
-           (lldb::user_id_t(ref.section() == DIERef::Section::DebugTypes)
-            << 63);
-  }
+  lldb::user_id_t GetUID(DIERef ref);
 
   virtual std::unique_ptr<SymbolFileDWARFDwo>
   GetDwoSymbolFileForCompileUnit(DWARFUnit &dwarf_cu,
@@ -290,6 +286,8 @@
   // the method returns a pointer to the base compile unit.
   virtual DWARFCompileUnit *GetBaseCompileUnit() { return nullptr; }
 
+  virtual llvm::Optional<uint32_t> GetDwoNum() { return llvm::None; }
+
   static bool
   DIEInDeclContext(const lldb_private::CompilerDeclContext *parent_decl_ctx,
                    const DWARFDIE &die);
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -1199,6 +1199,15 @@
       ast_parser->GetDeclForUIDFromDWARF(decl);
 }
 
+user_id_t SymbolFileDWARF::GetUID(DIERef ref) {
+  if (GetDebugMapSymfile())
+    return GetID() | ref.die_offset();
+
+  return user_id_t(GetDwoNum().getValueOr(0x7fffffff)) << 32 |
+         ref.die_offset() |
+         (lldb::user_id_t(ref.section() == DIERef::Section::DebugTypes) << 63);
+}
+
 llvm::Optional<SymbolFileDWARF::DecodedUID>
 SymbolFileDWARF::DecodeUID(lldb::user_id_t uid) {
   // This method can be called without going through the symbol vendor so we
@@ -1215,25 +1224,20 @@
     SymbolFileDWARF *dwarf = debug_map->GetSymbolFileByOSOIndex(
         debug_map->GetOSOIndexFromUserID(uid));
     return DecodedUID{
-        *dwarf,
-        {DIERef::Section::DebugInfo, DW_INVALID_OFFSET, dw_offset_t(uid)}};
+        *dwarf, {llvm::None, DIERef::Section::DebugInfo, dw_offset_t(uid)}};
   }
-  DIERef::Section section =
-      uid >> 63 ? DIERef::Section::DebugTypes : DIERef::Section::DebugInfo;
-  uint32_t dwarf_id = uid >> 32 & 0x7fffffff;
   dw_offset_t die_offset = uid;
-
   if (die_offset == DW_INVALID_OFFSET)
     return llvm::None;
 
-  SymbolFileDWARF *dwarf = this;
-  if (DebugInfo()) {
-    if (DWARFUnit *unit = DebugInfo()->GetUnitAtIndex(dwarf_id)) {
-      if (unit->GetDwoSymbolFile())
-        dwarf = unit->GetDwoSymbolFile();
-    }
-  }
-  return DecodedUID{*dwarf, {section, DW_INVALID_OFFSET, die_offset}};
+  DIERef::Section section =
+      uid >> 63 ? DIERef::Section::DebugTypes : DIERef::Section::DebugInfo;
+
+  llvm::Optional<uint32_t> dwo_num = uid >> 32 & 0x7fffffff;
+  if (*dwo_num == 0x7fffffff)
+    dwo_num = llvm::None;
+
+  return DecodedUID{*this, {dwo_num, section, die_offset}};
 }
 
 DWARFDIE
@@ -1493,6 +1497,14 @@
 
 DWARFDIE
 SymbolFileDWARF::GetDIE(const DIERef &die_ref) {
+  if (die_ref.dwo_num()) {
+    return DebugInfo()
+        ->GetUnitAtIndex(*die_ref.dwo_num())
+        ->GetDwoSymbolFile()
+        ->GetDIE(die_ref);
+  }
+
+
   DWARFDebugInfo *debug_info = DebugInfo();
   if (debug_info)
     return debug_info->GetDIE(die_ref);
@@ -2235,10 +2247,6 @@
 
   const uint32_t original_size = sc_list.GetSize();
 
-  DWARFDebugInfo *info = DebugInfo();
-  if (info == nullptr)
-    return 0;
-
   llvm::DenseSet<const DWARFDebugInfoEntry *> resolved_dies;
   DIEArray offsets;
   CompilerDeclContext empty_decl_ctx;
@@ -2246,7 +2254,7 @@
     parent_decl_ctx = &empty_decl_ctx;
 
   std::vector<DWARFDIE> dies;
-  m_index->GetFunctions(name, *info, *parent_decl_ctx, name_type_mask, dies);
+  m_index->GetFunctions(name, *this, *parent_decl_ctx, name_type_mask, dies);
   for (const DWARFDIE &die: dies) {
     if (resolved_dies.insert(die.GetDIE()).second)
       ResolveFunction(die, include_inlines, sc_list);
@@ -3081,7 +3089,8 @@
         sc.comp_unit->SetVariableList(variables);
 
         DIEArray die_offsets;
-        m_index->GetGlobalVariables(*dwarf_cu, die_offsets);
+        m_index->GetGlobalVariables(dwarf_cu->GetNonSkeletonUnit(),
+                                    die_offsets);
         const size_t num_matches = die_offsets.size();
         if (num_matches) {
           for (size_t i = 0; i < num_matches; ++i) {
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h
@@ -44,6 +44,8 @@
 
   DWARFCompileUnit *GetBaseCompileUnit() override { return &m_base_dwarf_cu; }
 
+  llvm::Optional<uint32_t> GetDwoNum() override { return GetID() >> 32; }
+
 protected:
   void LoadSectionData(lldb::SectionType sect_type,
                        lldb_private::DWARFDataExtractor &data) override;
Index: lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
===================================================================
--- lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
+++ lldb/trunk/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp
@@ -124,8 +124,7 @@
 
 DWARFDIE
 SymbolFileDWARFDwo::GetDIE(const DIERef &die_ref) {
-  lldbassert(!die_ref.unit_offset() ||
-             *die_ref.unit_offset() == m_base_dwarf_cu.GetOffset());
-  return DebugInfo()->GetDIEForDIEOffset(die_ref.section(),
-                                         die_ref.die_offset());
+  if (*die_ref.dwo_num() == GetDwoNum())
+    return DebugInfo()->GetDIE(die_ref);
+  return GetBaseSymbolFile().GetDIE(die_ref);
 }