Index: lib/DebugInfo/DWARFContext.h
===================================================================
--- lib/DebugInfo/DWARFContext.h
+++ lib/DebugInfo/DWARFContext.h
@@ -81,61 +81,61 @@
   /// Get compile units in this context.
   cu_iterator_range compile_units() {
     parseCompileUnits();
-    return cu_iterator_range(CUs.begin(), CUs.end());
+    return CUs.Units();
   }
 
   /// Get type units in this context.
   tu_iterator_range type_units() {
     parseTypeUnits();
-    return tu_iterator_range(TUs.begin(), TUs.end());
+    return TUs.Units();
   }
 
   /// Get compile units in the DWO context.
   cu_iterator_range dwo_compile_units() {
     parseDWOCompileUnits();
-    return cu_iterator_range(DWOCUs.begin(), DWOCUs.end());
+    return DWOCUs.Units();
   }
 
   /// Get type units in the DWO context.
   tu_iterator_range dwo_type_units() {
     parseDWOTypeUnits();
-    return tu_iterator_range(DWOTUs.begin(), DWOTUs.end());
+    return DWOTUs.Units();
   }
 
   /// Get the number of compile units in this context.
   unsigned getNumCompileUnits() {
     parseCompileUnits();
-    return CUs.size();
+    return CUs.getNumUnits();
   }
 
   /// Get the number of compile units in this context.
   unsigned getNumTypeUnits() {
     parseTypeUnits();
-    return TUs.size();
+    return TUs.getNumUnits();
   }
 
   /// Get the number of compile units in the DWO context.
   unsigned getNumDWOCompileUnits() {
     parseDWOCompileUnits();
-    return DWOCUs.size();
+    return DWOCUs.getNumUnits();
   }
 
   /// Get the number of compile units in the DWO context.
   unsigned getNumDWOTypeUnits() {
     parseDWOTypeUnits();
-    return DWOTUs.size();
+    return DWOTUs.getNumUnits();
   }
 
   /// Get the compile unit at the specified index for this compile unit.
   DWARFCompileUnit *getCompileUnitAtIndex(unsigned index) {
     parseCompileUnits();
-    return CUs[index].get();
+    return CUs.getUnitAtIndex(index);
   }
 
   /// Get the compile unit at the specified index for the DWO compile units.
   DWARFCompileUnit *getDWOCompileUnitAtIndex(unsigned index) {
     parseDWOCompileUnits();
-    return DWOCUs[index].get();
+    return DWOCUs.getUnitAtIndex(index);
   }
 
   /// Get a pointer to the parsed DebugAbbrev object.
Index: lib/DebugInfo/DWARFContext.cpp
===================================================================
--- lib/DebugInfo/DWARFContext.cpp
+++ lib/DebugInfo/DWARFContext.cpp
@@ -247,7 +247,7 @@
   Loc.reset(new DWARFDebugLoc(getLocSection().Relocs));
   // assume all compile units have the same address byte size
   if (getNumCompileUnits())
-    Loc->parse(LocData, getCompileUnitAtIndex(0)->getAddressByteSize());
+    Loc->parse(LocData, CUs.getUnitAtIndex(0)->getAddressByteSize());
   return Loc.get();
 }
 
@@ -312,7 +312,7 @@
 }
 
 void DWARFContext::parseCompileUnits() {
-  if (!CUs.empty())
+  if (CUs.getNumUnits() != 0)
     return;
   uint32_t offset = 0;
   const DataExtractor &DIData = DataExtractor(getInfoSection().Data,
@@ -325,13 +325,13 @@
     if (!CU->extract(DIData, &offset)) {
       break;
     }
-    CUs.push_back(std::move(CU));
-    offset = CUs.back()->getNextUnitOffset();
+    offset = CU->getNextUnitOffset();
+    CUs.addUnit(std::move(CU));
   }
 }
 
 void DWARFContext::parseTypeUnits() {
-  if (!TUs.empty())
+  if (TUs.getNumUnits() != 0)
     return;
   for (const auto &I : getTypesSections()) {
     uint32_t offset = 0;
@@ -344,14 +344,14 @@
            &I.second.Relocs, isLittleEndian(), TUs));
       if (!TU->extract(DIData, &offset))
         break;
-      TUs.push_back(std::move(TU));
-      offset = TUs.back()->getNextUnitOffset();
+      offset = TU->getNextUnitOffset();
+      TUs.addUnit(std::move(TU));
     }
   }
 }
 
 void DWARFContext::parseDWOCompileUnits() {
-  if (!DWOCUs.empty())
+  if (DWOCUs.getNumUnits() != 0)
     return;
   uint32_t offset = 0;
   const DataExtractor &DIData =
@@ -364,13 +364,13 @@
     if (!DWOCU->extract(DIData, &offset)) {
       break;
     }
-    DWOCUs.push_back(std::move(DWOCU));
-    offset = DWOCUs.back()->getNextUnitOffset();
+    offset = DWOCU->getNextUnitOffset();
+    DWOCUs.addUnit(std::move(DWOCU));
   }
 }
 
 void DWARFContext::parseDWOTypeUnits() {
-  if (!DWOTUs.empty())
+  if (DWOTUs.getNumUnits() != 0)
     return;
   for (const auto &I : getTypesDWOSections()) {
     uint32_t offset = 0;
@@ -383,8 +383,8 @@
           &I.second.Relocs, isLittleEndian(), DWOTUs));
       if (!TU->extract(DIData, &offset))
         break;
-      DWOTUs.push_back(std::move(TU));
-      offset = DWOTUs.back()->getNextUnitOffset();
+      offset = TU->getNextUnitOffset();
+      DWOTUs.addUnit(std::move(TU));
     }
   }
 }
Index: lib/DebugInfo/DWARFUnit.h
===================================================================
--- lib/DebugInfo/DWARFUnit.h
+++ lib/DebugInfo/DWARFUnit.h
@@ -65,6 +65,22 @@
   typedef typename UnitVector::iterator iterator;
   typedef llvm::iterator_range<typename UnitVector::iterator> iterator_range;
 
+  iterator_range Units() {
+    return iterator_range(this->begin(), this->end());
+  }
+
+  unsigned getNumUnits() const {
+    return this->size();
+  }
+
+  UnitType *getUnitAtIndex(unsigned Index) {
+    return Index < this->size() ? (*this)[Index].get() : nullptr;
+  }
+
+  void addUnit(std::unique_ptr<UnitType> &&Unit) {
+    this->push_back(std::move(Unit));
+  }
+
   UnitType *getUnitForOffset(uint32_t Offset) const {
     auto *CU = std::lower_bound(this->begin(), this->end(), Offset,
                                 UnitOffsetComparator());