MFC 261991:

Upgrade our copy of llvm/clang to 3.4 release.  This version supports
all of the features in the current working draft of the upcoming C++
standard, provisionally named C++1y.

The code generator's performance is greatly increased, and the loop
auto-vectorizer is now enabled at -Os and -O2 in addition to -O3.  The
PowerPC backend has made several major improvements to code generation
quality and compile time, and the X86, SPARC, ARM32, Aarch64 and SystemZ
backends have all seen major feature work.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.4/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.4/tools/clang/docs/ReleaseNotes.html>

MFC 262121 (by emaste):

Update lldb for clang/llvm 3.4 import

This commit largely restores the lldb source to the upstream r196259
snapshot with the addition of threaded inferior support and a few bug
fixes.

Specific upstream lldb revisions restored include:
   SVN      git
  181387  779e6ac
  181703  7bef4e2
  182099  b31044e
  182650  f2dcf35
  182683  0d91b80
  183862  15c1774
  183929  99447a6
  184177  0b2934b
  184948  4dc3761
  184954  007e7bc
  186990  eebd175

Sponsored by:	DARPA, AFRL

MFC 262186 (by emaste):

Fix mismerge in r262121

A break statement was lost in the merge.  The error had no functional
impact, but restore it to reduce the diff against upstream.

MFC 262303:

Pull in r197521 from upstream clang trunk (by rdivacky):

  Use the integrated assembler by default on FreeBSD/ppc and ppc64.

Requested by:	jhibbits

MFC 262611:

Pull in r196874 from upstream llvm trunk:

  Fix a crash that occurs when PWD is invalid.

  MCJIT needs to be able to run in hostile environments, even when PWD
  is invalid. There's no need to crash MCJIT in this case.

  The obvious fix is to simply leave MCContext's CompilationDir empty
  when PWD can't be determined. This way, MCJIT clients,
  and other clients that link with LLVM don't need a valid working directory.

  If we do want to guarantee valid CompilationDir, that should be done
  only for clients of getCompilationDir(). This is as simple as checking
  for an empty string.

  The only current use of getCompilationDir is EmitGenDwarfInfo, which
  won't conceivably run with an invalid working dir. However, in the
  purely hypothetically and untestable case that this happens, the
  AT_comp_dir will be omitted from the compilation_unit DIE.

This should help fix assertions occurring with ports-mgmt/tinderbox,
when it is using jails, and sometimes invalidates clang's current
working directory.

Reported by:	decke

MFC 262809:

Pull in r203007 from upstream clang trunk:

  Don't produce an alias between destructors with different calling conventions.

  Fixes pr19007.

(Please note that is an LLVM PR identifier, not a FreeBSD one.)

This should fix Firefox and/or libxul crashes (due to problems with
regparm/stdcall calling conventions) on i386.

Reported by:	multiple users on freebsd-current
PR:		bin/187103

MFC 263048:

Repair recognition of "CC" as an alias for the C++ compiler, since it
was silently broken by upstream for a Windows-specific use-case.

Apparently some versions of CMake still rely on this archaic feature...

Reported by:	rakuco

MFC 263049:

Garbage collect the old way of adding the libstdc++ include directories
in clang's InitHeaderSearch.cpp.  This has been superseded by David
Chisnall's commit in r255321.

Moreover, if libc++ is used, the libstdc++ include directories should
not be in the search path at all.  These directories are now only used
if you pass -stdlib=libstdc++.

1 files changed, 1016 insertions, 652 deletions

diff --git a/contrib/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/contrib/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 1e706cc..d1e1ad1 100644
--- a/contrib/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/contrib/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -14,6 +14,7 @@
 #define DEBUG_TYPE "dwarfdebug"
 #include "DwarfDebug.h"
 #include "DIE.h"
+#include "DIEHash.h"
 #include "DwarfAccelTable.h"
 #include "DwarfCompileUnit.h"
 #include "llvm/ADT/STLExtras.h"
@@ -34,8 +35,10 @@
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/Dwarf.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormattedStream.h"
+#include "llvm/Support/MD5.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Timer.h"
 #include "llvm/Support/ValueHandle.h"
@@ -46,61 +49,69 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 using namespace llvm;
 
-static cl::opt<bool> DisableDebugInfoPrinting("disable-debug-info-print",
-                                              cl::Hidden,
-     cl::desc("Disable debug info printing"));
+static cl::opt<bool>
+DisableDebugInfoPrinting("disable-debug-info-print", cl::Hidden,
+                         cl::desc("Disable debug info printing"));
 
-static cl::opt<bool> UnknownLocations("use-unknown-locations", cl::Hidden,
-     cl::desc("Make an absence of debug location information explicit."),
-     cl::init(false));
+static cl::opt<bool> UnknownLocations(
+    "use-unknown-locations", cl::Hidden,
+    cl::desc("Make an absence of debug location information explicit."),
+    cl::init(false));
 
-static cl::opt<bool> GenerateDwarfPubNamesSection("generate-dwarf-pubnames",
-     cl::Hidden, cl::init(false),
-     cl::desc("Generate DWARF pubnames section"));
+static cl::opt<bool>
+GenerateODRHash("generate-odr-hash", cl::Hidden,
+                cl::desc("Add an ODR hash to external type DIEs."),
+                cl::init(false));
 
-namespace {
-  enum DefaultOnOff {
-    Default, Enable, Disable
-  };
-}
-
-static cl::opt<DefaultOnOff> DwarfAccelTables("dwarf-accel-tables", cl::Hidden,
-     cl::desc("Output prototype dwarf accelerator tables."),
-     cl::values(
-                clEnumVal(Default, "Default for platform"),
-                clEnumVal(Enable, "Enabled"),
-                clEnumVal(Disable, "Disabled"),
-                clEnumValEnd),
-     cl::init(Default));
-
-static cl::opt<DefaultOnOff> DarwinGDBCompat("darwin-gdb-compat", cl::Hidden,
-     cl::desc("Compatibility with Darwin gdb."),
-     cl::values(
-                clEnumVal(Default, "Default for platform"),
-                clEnumVal(Enable, "Enabled"),
-                clEnumVal(Disable, "Disabled"),
-                clEnumValEnd),
-     cl::init(Default));
-
-static cl::opt<DefaultOnOff> SplitDwarf("split-dwarf", cl::Hidden,
-     cl::desc("Output prototype dwarf split debug info."),
-     cl::values(
-                clEnumVal(Default, "Default for platform"),
-                clEnumVal(Enable, "Enabled"),
-                clEnumVal(Disable, "Disabled"),
-                clEnumValEnd),
-     cl::init(Default));
+static cl::opt<bool>
+GenerateCUHash("generate-cu-hash", cl::Hidden,
+               cl::desc("Add the CU hash as the dwo_id."),
+               cl::init(false));
 
-namespace {
-  const char *DWARFGroupName = "DWARF Emission";
-  const char *DbgTimerName = "DWARF Debug Writer";
+static cl::opt<bool>
+GenerateGnuPubSections("generate-gnu-dwarf-pub-sections", cl::Hidden,
+                       cl::desc("Generate GNU-style pubnames and pubtypes"),
+                       cl::init(false));
 
-  struct CompareFirst {
-    template <typename T> bool operator()(const T &lhs, const T &rhs) const {
-      return lhs.first < rhs.first;
-    }
-  };
-} // end anonymous namespace
+namespace {
+enum DefaultOnOff {
+  Default,
+  Enable,
+  Disable
+};
+}
+
+static cl::opt<DefaultOnOff>
+DwarfAccelTables("dwarf-accel-tables", cl::Hidden,
+                 cl::desc("Output prototype dwarf accelerator tables."),
+                 cl::values(clEnumVal(Default, "Default for platform"),
+                            clEnumVal(Enable, "Enabled"),
+                            clEnumVal(Disable, "Disabled"), clEnumValEnd),
+                 cl::init(Default));
+
+static cl::opt<DefaultOnOff>
+SplitDwarf("split-dwarf", cl::Hidden,
+           cl::desc("Output prototype dwarf split debug info."),
+           cl::values(clEnumVal(Default, "Default for platform"),
+                      clEnumVal(Enable, "Enabled"),
+                      clEnumVal(Disable, "Disabled"), clEnumValEnd),
+           cl::init(Default));
+
+static cl::opt<DefaultOnOff>
+DwarfPubSections("generate-dwarf-pub-sections", cl::Hidden,
+                 cl::desc("Generate DWARF pubnames and pubtypes sections"),
+                 cl::values(clEnumVal(Default, "Default for platform"),
+                            clEnumVal(Enable, "Enabled"),
+                            clEnumVal(Disable, "Disabled"), clEnumValEnd),
+                 cl::init(Default));
+
+static cl::opt<unsigned>
+DwarfVersionNumber("dwarf-version", cl::Hidden,
+                   cl::desc("Generate DWARF for dwarf version."),
+                   cl::init(0));
+
+static const char *const DWARFGroupName = "DWARF Emission";
+static const char *const DbgTimerName = "DWARF Debug Writer";
 
 //===----------------------------------------------------------------------===//
 
@@ -110,6 +121,13 @@ static const unsigned InitAbbreviationsSetSize = 9; // log2(512)
 
 namespace llvm {
 
+/// resolve - Look in the DwarfDebug map for the MDNode that
+/// corresponds to the reference.
+template <typename T>
+T DbgVariable::resolve(DIRef<T> Ref) const {
+  return DD->resolve(Ref);
+}
+
 DIType DbgVariable::getType() const {
   DIType Ty = Var.getType();
   // FIXME: isBlockByrefVariable should be reformulated in terms of complex
@@ -140,21 +158,16 @@ DIType DbgVariable::getType() const {
        the pointers and __Block_byref_x_VarName struct to find the actual
        value of the variable.  The function addBlockByrefType does this.  */
     DIType subType = Ty;
-    unsigned tag = Ty.getTag();
-
-    if (tag == dwarf::DW_TAG_pointer_type) {
-      DIDerivedType DTy = DIDerivedType(Ty);
-      subType = DTy.getTypeDerivedFrom();
-    }
+    uint16_t tag = Ty.getTag();
 
-    DICompositeType blockStruct = DICompositeType(subType);
-    DIArray Elements = blockStruct.getTypeArray();
+    if (tag == dwarf::DW_TAG_pointer_type)
+      subType = resolve(DIDerivedType(Ty).getTypeDerivedFrom());
 
+    DIArray Elements = DICompositeType(subType).getTypeArray();
     for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
-      DIDescriptor Element = Elements.getElement(i);
-      DIDerivedType DT = DIDerivedType(Element);
+      DIDerivedType DT(Elements.getElement(i));
       if (getName() == DT.getName())
-        return (DT.getTypeDerivedFrom());
+        return (resolve(DT.getTypeDerivedFrom()));
     }
   }
   return Ty;
@@ -162,15 +175,23 @@ DIType DbgVariable::getType() const {
 
 } // end llvm namespace
 
+/// Return Dwarf Version by checking module flags.
+static unsigned getDwarfVersionFromModule(const Module *M) {
+  Value *Val = M->getModuleFlag("Dwarf Version");
+  if (!Val)
+    return dwarf::DWARF_VERSION;
+  return cast<ConstantInt>(Val)->getZExtValue();
+}
+
 DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   : Asm(A), MMI(Asm->MMI), FirstCU(0),
     AbbreviationsSet(InitAbbreviationsSetSize),
     SourceIdMap(DIEValueAllocator),
     PrevLabel(NULL), GlobalCUIndexCount(0),
-    InfoHolder(A, &AbbreviationsSet, &Abbreviations, "info_string",
+    InfoHolder(A, &AbbreviationsSet, Abbreviations, "info_string",
                DIEValueAllocator),
     SkeletonAbbrevSet(InitAbbreviationsSetSize),
-    SkeletonHolder(A, &SkeletonAbbrevSet, &SkeletonAbbrevs, "skel_string",
+    SkeletonHolder(A, &SkeletonAbbrevSet, SkeletonAbbrevs, "skel_string",
                    DIEValueAllocator) {
 
   DwarfInfoSectionSym = DwarfAbbrevSectionSym = 0;
@@ -180,37 +201,34 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   DwarfAbbrevDWOSectionSym = DwarfStrDWOSectionSym = 0;
   FunctionBeginSym = FunctionEndSym = 0;
 
-  // Turn on accelerator tables and older gdb compatibility
-  // for Darwin.
+  // Turn on accelerator tables for Darwin by default, pubnames by
+  // default for non-Darwin, and handle split dwarf.
   bool IsDarwin = Triple(A->getTargetTriple()).isOSDarwin();
-  if (DarwinGDBCompat == Default) {
-    if (IsDarwin)
-      IsDarwinGDBCompat = true;
-    else
-      IsDarwinGDBCompat = false;
-  } else
-    IsDarwinGDBCompat = DarwinGDBCompat == Enable ? true : false;
 
-  if (DwarfAccelTables == Default) {
-    if (IsDarwin)
-      HasDwarfAccelTables = true;
-    else
-      HasDwarfAccelTables = false;
-  } else
-    HasDwarfAccelTables = DwarfAccelTables == Enable ? true : false;
+  if (DwarfAccelTables == Default)
+    HasDwarfAccelTables = IsDarwin;
+  else
+    HasDwarfAccelTables = DwarfAccelTables == Enable;
 
   if (SplitDwarf == Default)
     HasSplitDwarf = false;
   else
-    HasSplitDwarf = SplitDwarf == Enable ? true : false;
+    HasSplitDwarf = SplitDwarf == Enable;
+
+  if (DwarfPubSections == Default)
+    HasDwarfPubSections = !IsDarwin;
+  else
+    HasDwarfPubSections = DwarfPubSections == Enable;
+
+  DwarfVersion = DwarfVersionNumber
+                     ? DwarfVersionNumber
+                     : getDwarfVersionFromModule(MMI->getModule());
 
   {
     NamedRegionTimer T(DbgTimerName, DWARFGroupName, TimePassesIsEnabled);
     beginModule();
   }
 }
-DwarfDebug::~DwarfDebug() {
-}
 
 // Switch to the specified MCSection and emit an assembler
 // temporary label to it if SymbolStem is specified.
@@ -247,48 +265,37 @@ unsigned DwarfUnits::getStringPoolIndex(StringRef Str) {
   return Entry.second;
 }
 
-unsigned DwarfUnits::getAddrPoolIndex(MCSymbol *Sym) {
-  std::pair<MCSymbol*, unsigned> &Entry = AddressPool[Sym];
-  if (Entry.first) return Entry.second;
+unsigned DwarfUnits::getAddrPoolIndex(const MCSymbol *Sym) {
+  return getAddrPoolIndex(MCSymbolRefExpr::Create(Sym, Asm->OutContext));
+}
 
-  Entry.second = NextAddrPoolNumber++;
-  Entry.first = Sym;
-  return Entry.second;
+unsigned DwarfUnits::getAddrPoolIndex(const MCExpr *Sym) {
+  std::pair<DenseMap<const MCExpr *, unsigned>::iterator, bool> P =
+      AddressPool.insert(std::make_pair(Sym, NextAddrPoolNumber));
+  if (P.second)
+    ++NextAddrPoolNumber;
+  return P.first->second;
 }
 
 // Define a unique number for the abbreviation.
 //
 void DwarfUnits::assignAbbrevNumber(DIEAbbrev &Abbrev) {
-  // Profile the node so that we can make it unique.
-  FoldingSetNodeID ID;
-  Abbrev.Profile(ID);
-
   // Check the set for priors.
   DIEAbbrev *InSet = AbbreviationsSet->GetOrInsertNode(&Abbrev);
 
   // If it's newly added.
   if (InSet == &Abbrev) {
     // Add to abbreviation list.
-    Abbreviations->push_back(&Abbrev);
+    Abbreviations.push_back(&Abbrev);
 
     // Assign the vector position + 1 as its number.
-    Abbrev.setNumber(Abbreviations->size());
+    Abbrev.setNumber(Abbreviations.size());
   } else {
     // Assign existing abbreviation number.
     Abbrev.setNumber(InSet->getNumber());
   }
 }
 
-// If special LLVM prefix that is used to inform the asm
-// printer to not emit usual symbol prefix before the symbol name is used then
-// return linkage name after skipping this special LLVM prefix.
-static StringRef getRealLinkageName(StringRef LinkageName) {
-  char One = '\1';
-  if (LinkageName.startswith(StringRef(&One, 1)))
-    return LinkageName.substr(1);
-  return LinkageName;
-}
-
 static bool isObjCClass(StringRef Name) {
   return Name.startswith("+") || Name.startswith("-");
 }
@@ -296,12 +303,7 @@ static bool isObjCClass(StringRef Name) {
 static bool hasObjCCategory(StringRef Name) {
   if (!isObjCClass(Name)) return false;
 
-  size_t pos = Name.find(')');
-  if (pos != std::string::npos) {
-    if (Name[pos+1] != ' ') return false;
-    return true;
-  }
-  return false;
+  return Name.find(") ") != StringRef::npos;
 }
 
 static void getObjCClassCategory(StringRef In, StringRef &Class,
@@ -321,11 +323,20 @@ static StringRef getObjCMethodName(StringRef In) {
   return In.slice(In.find(' ') + 1, In.find(']'));
 }
 
+// Helper for sorting sections into a stable output order.
+static bool SectionSort(const MCSection *A, const MCSection *B) {
+    std::string LA = (A ? A->getLabelBeginName() : "");
+    std::string LB = (B ? B->getLabelBeginName() : "");
+    return LA < LB;
+}
+
 // Add the various names to the Dwarf accelerator table names.
+// TODO: Determine whether or not we should add names for programs
+// that do not have a DW_AT_name or DW_AT_linkage_name field - this
+// is only slightly different than the lookup of non-standard ObjC names.
 static void addSubprogramNames(CompileUnit *TheCU, DISubprogram SP,
                                DIE* Die) {
   if (!SP.isDefinition()) return;
-
   TheCU->addAccelName(SP.getName(), Die);
 
   // If the linkage name is different than the name, go ahead and output
@@ -346,30 +357,34 @@ static void addSubprogramNames(CompileUnit *TheCU, DISubprogram SP,
   }
 }
 
+/// isSubprogramContext - Return true if Context is either a subprogram
+/// or another context nested inside a subprogram.
+bool DwarfDebug::isSubprogramContext(const MDNode *Context) {
+  if (!Context)
+    return false;
+  DIDescriptor D(Context);
+  if (D.isSubprogram())
+    return true;
+  if (D.isType())
+    return isSubprogramContext(resolve(DIType(Context).getContext()));
+  return false;
+}
+
 // Find DIE for the given subprogram and attach appropriate DW_AT_low_pc
 // and DW_AT_high_pc attributes. If there are global variables in this
 // scope then create and insert DIEs for these variables.
-DIE *DwarfDebug::updateSubprogramScopeDIE(CompileUnit *SPCU,
-                                          const MDNode *SPNode) {
-  DIE *SPDie = SPCU->getDIE(SPNode);
+DIE *DwarfDebug::updateSubprogramScopeDIE(CompileUnit *SPCU, DISubprogram SP) {
+  DIE *SPDie = SPCU->getDIE(SP);
 
   assert(SPDie && "Unable to find subprogram DIE!");
-  DISubprogram SP(SPNode);
 
   // If we're updating an abstract DIE, then we will be adding the children and
   // object pointer later on. But what we don't want to do is process the
   // concrete DIE twice.
-  DIE *AbsSPDIE = AbstractSPDies.lookup(SPNode);
-  if (AbsSPDIE) {
-    bool InSameCU = (AbsSPDIE->getCompileUnit() == SPCU->getCUDie());
+  if (DIE *AbsSPDIE = AbstractSPDies.lookup(SP)) {
     // Pick up abstract subprogram DIE.
-    SPDie = new DIE(dwarf::DW_TAG_subprogram);
-    // If AbsSPDIE belongs to a different CU, use DW_FORM_ref_addr instead of
-    // DW_FORM_ref4.
-    SPCU->addDIEEntry(SPDie, dwarf::DW_AT_abstract_origin,
-                      InSameCU ? dwarf::DW_FORM_ref4 : dwarf::DW_FORM_ref_addr,
-                      AbsSPDIE);
-    SPCU->addDie(SPDie);
+    SPDie = SPCU->createAndAddDIE(dwarf::DW_TAG_subprogram, *SPCU->getCUDie());
+    SPCU->addDIEEntry(SPDie, dwarf::DW_AT_abstract_origin, AbsSPDIE);
   } else {
     DISubprogram SPDecl = SP.getFunctionDeclaration();
     if (!SPDecl.isSubprogram()) {
@@ -378,32 +393,31 @@ DIE *DwarfDebug::updateSubprogramScopeDIE(CompileUnit *SPCU,
       // function then gdb prefers the definition at top level and but does not
       // expect specification DIE in parent function. So avoid creating
       // specification DIE for a function defined inside a function.
-      if (SP.isDefinition() && !SP.getContext().isCompileUnit() &&
-          !SP.getContext().isFile() &&
-          !isSubprogramContext(SP.getContext())) {
+      DIScope SPContext = resolve(SP.getContext());
+      if (SP.isDefinition() && !SPContext.isCompileUnit() &&
+          !SPContext.isFile() &&
+          !isSubprogramContext(SPContext)) {
         SPCU->addFlag(SPDie, dwarf::DW_AT_declaration);
 
         // Add arguments.
         DICompositeType SPTy = SP.getType();
         DIArray Args = SPTy.getTypeArray();
-        unsigned SPTag = SPTy.getTag();
+        uint16_t SPTag = SPTy.getTag();
         if (SPTag == dwarf::DW_TAG_subroutine_type)
           for (unsigned i = 1, N = Args.getNumElements(); i < N; ++i) {
-            DIE *Arg = new DIE(dwarf::DW_TAG_formal_parameter);
-            DIType ATy = DIType(Args.getElement(i));
+            DIE *Arg =
+                SPCU->createAndAddDIE(dwarf::DW_TAG_formal_parameter, *SPDie);
+            DIType ATy(Args.getElement(i));
             SPCU->addType(Arg, ATy);
             if (ATy.isArtificial())
               SPCU->addFlag(Arg, dwarf::DW_AT_artificial);
             if (ATy.isObjectPointer())
-              SPCU->addDIEEntry(SPDie, dwarf::DW_AT_object_pointer,
-                                dwarf::DW_FORM_ref4, Arg);
-            SPDie->addChild(Arg);
+              SPCU->addDIEEntry(SPDie, dwarf::DW_AT_object_pointer, Arg);
           }
         DIE *SPDeclDie = SPDie;
-        SPDie = new DIE(dwarf::DW_TAG_subprogram);
-        SPCU->addDIEEntry(SPDie, dwarf::DW_AT_specification,
-                          dwarf::DW_FORM_ref4, SPDeclDie);
-        SPCU->addDie(SPDie);
+        SPDie =
+            SPCU->createAndAddDIE(dwarf::DW_TAG_subprogram, *SPCU->getCUDie());
+        SPCU->addDIEEntry(SPDie, dwarf::DW_AT_specification, SPDeclDie);
       }
     }
   }
@@ -425,40 +439,64 @@ DIE *DwarfDebug::updateSubprogramScopeDIE(CompileUnit *SPCU,
   return SPDie;
 }
 
+/// Check whether we should create a DIE for the given Scope, return true
+/// if we don't create a DIE (the corresponding DIE is null).
+bool DwarfDebug::isLexicalScopeDIENull(LexicalScope *Scope) {
+  if (Scope->isAbstractScope())
+    return false;
+
+  // We don't create a DIE if there is no Range.
+  const SmallVectorImpl<InsnRange> &Ranges = Scope->getRanges();
+  if (Ranges.empty())
+    return true;
+
+  if (Ranges.size() > 1)
+    return false;
+
+  // We don't create a DIE if we have a single Range and the end label
+  // is null.
+  SmallVectorImpl<InsnRange>::const_iterator RI = Ranges.begin();
+  MCSymbol *End = getLabelAfterInsn(RI->second);
+  return !End;
+}
+
 // Construct new DW_TAG_lexical_block for this scope and attach
 // DW_AT_low_pc/DW_AT_high_pc labels.
 DIE *DwarfDebug::constructLexicalScopeDIE(CompileUnit *TheCU,
                                           LexicalScope *Scope) {
+  if (isLexicalScopeDIENull(Scope))
+    return 0;
+
   DIE *ScopeDIE = new DIE(dwarf::DW_TAG_lexical_block);
   if (Scope->isAbstractScope())
     return ScopeDIE;
 
-  const SmallVector<InsnRange, 4> &Ranges = Scope->getRanges();
-  if (Ranges.empty())
-    return 0;
-
-  SmallVector<InsnRange, 4>::const_iterator RI = Ranges.begin();
+  const SmallVectorImpl<InsnRange> &Ranges = Scope->getRanges();
+  // If we have multiple ranges, emit them into the range section.
   if (Ranges.size() > 1) {
     // .debug_range section has not been laid out yet. Emit offset in
     // .debug_range as a uint, size 4, for now. emitDIE will handle
     // DW_AT_ranges appropriately.
-    TheCU->addUInt(ScopeDIE, dwarf::DW_AT_ranges, dwarf::DW_FORM_data4,
-                   DebugRangeSymbols.size()
-                   * Asm->getDataLayout().getPointerSize());
-    for (SmallVector<InsnRange, 4>::const_iterator RI = Ranges.begin(),
+    TheCU->addSectionOffset(ScopeDIE, dwarf::DW_AT_ranges,
+                            DebugRangeSymbols.size() *
+                                Asm->getDataLayout().getPointerSize());
+    for (SmallVectorImpl<InsnRange>::const_iterator RI = Ranges.begin(),
          RE = Ranges.end(); RI != RE; ++RI) {
       DebugRangeSymbols.push_back(getLabelBeforeInsn(RI->first));
       DebugRangeSymbols.push_back(getLabelAfterInsn(RI->second));
     }
+
+    // Terminate the range list.
     DebugRangeSymbols.push_back(NULL);
     DebugRangeSymbols.push_back(NULL);
     return ScopeDIE;
   }
 
+  // Construct the address range for this DIE.
+  SmallVectorImpl<InsnRange>::const_iterator RI = Ranges.begin();
   MCSymbol *Start = getLabelBeforeInsn(RI->first);
   MCSymbol *End = getLabelAfterInsn(RI->second);
-
-  if (End == 0) return 0;
+  assert(End && "End label should not be null!");
 
   assert(Start->isDefined() && "Invalid starting label for an inlined scope!");
   assert(End->isDefined() && "Invalid end label for an inlined scope!");
@@ -473,7 +511,7 @@ DIE *DwarfDebug::constructLexicalScopeDIE(CompileUnit *TheCU,
 // represent this concrete inlined copy of the function.
 DIE *DwarfDebug::constructInlinedScopeDIE(CompileUnit *TheCU,
                                           LexicalScope *Scope) {
-  const SmallVector<InsnRange, 4> &Ranges = Scope->getRanges();
+  const SmallVectorImpl<InsnRange> &Ranges = Scope->getRanges();
   assert(Ranges.empty() == false &&
          "LexicalScope does not have instruction markers!");
 
@@ -487,30 +525,17 @@ DIE *DwarfDebug::constructInlinedScopeDIE(CompileUnit *TheCU,
     return NULL;
   }
 
-  SmallVector<InsnRange, 4>::const_iterator RI = Ranges.begin();
-  MCSymbol *StartLabel = getLabelBeforeInsn(RI->first);
-  MCSymbol *EndLabel = getLabelAfterInsn(RI->second);
-
-  if (StartLabel == 0 || EndLabel == 0) {
-    llvm_unreachable("Unexpected Start and End labels for an inlined scope!");
-  }
-  assert(StartLabel->isDefined() &&
-         "Invalid starting label for an inlined scope!");
-  assert(EndLabel->isDefined() &&
-         "Invalid end label for an inlined scope!");
-
   DIE *ScopeDIE = new DIE(dwarf::DW_TAG_inlined_subroutine);
-  TheCU->addDIEEntry(ScopeDIE, dwarf::DW_AT_abstract_origin,
-                     dwarf::DW_FORM_ref4, OriginDIE);
+  TheCU->addDIEEntry(ScopeDIE, dwarf::DW_AT_abstract_origin, OriginDIE);
 
   if (Ranges.size() > 1) {
     // .debug_range section has not been laid out yet. Emit offset in
     // .debug_range as a uint, size 4, for now. emitDIE will handle
     // DW_AT_ranges appropriately.
-    TheCU->addUInt(ScopeDIE, dwarf::DW_AT_ranges, dwarf::DW_FORM_data4,
-                   DebugRangeSymbols.size()
-                   * Asm->getDataLayout().getPointerSize());
-    for (SmallVector<InsnRange, 4>::const_iterator RI = Ranges.begin(),
+    TheCU->addSectionOffset(ScopeDIE, dwarf::DW_AT_ranges,
+                            DebugRangeSymbols.size() *
+                                Asm->getDataLayout().getPointerSize());
+    for (SmallVectorImpl<InsnRange>::const_iterator RI = Ranges.begin(),
          RE = Ranges.end(); RI != RE; ++RI) {
       DebugRangeSymbols.push_back(getLabelBeforeInsn(RI->first));
       DebugRangeSymbols.push_back(getLabelAfterInsn(RI->second));
@@ -518,31 +543,29 @@ DIE *DwarfDebug::constructInlinedScopeDIE(CompileUnit *TheCU,
     DebugRangeSymbols.push_back(NULL);
     DebugRangeSymbols.push_back(NULL);
   } else {
+    SmallVectorImpl<InsnRange>::const_iterator RI = Ranges.begin();
+    MCSymbol *StartLabel = getLabelBeforeInsn(RI->first);
+    MCSymbol *EndLabel = getLabelAfterInsn(RI->second);
+
+    if (StartLabel == 0 || EndLabel == 0)
+      llvm_unreachable("Unexpected Start and End labels for an inlined scope!");
+
+    assert(StartLabel->isDefined() &&
+           "Invalid starting label for an inlined scope!");
+    assert(EndLabel->isDefined() && "Invalid end label for an inlined scope!");
+
     TheCU->addLabelAddress(ScopeDIE, dwarf::DW_AT_low_pc, StartLabel);
     TheCU->addLabelAddress(ScopeDIE, dwarf::DW_AT_high_pc, EndLabel);
   }
 
   InlinedSubprogramDIEs.insert(OriginDIE);
 
-  // Track the start label for this inlined function.
-  //.debug_inlined section specification does not clearly state how
-  // to emit inlined scope that is split into multiple instruction ranges.
-  // For now, use first instruction range and emit low_pc/high_pc pair and
-  // corresponding .debug_inlined section entry for this pair.
-  DenseMap<const MDNode *, SmallVector<InlineInfoLabels, 4> >::iterator
-    I = InlineInfo.find(InlinedSP);
-
-  if (I == InlineInfo.end()) {
-    InlineInfo[InlinedSP].push_back(std::make_pair(StartLabel, ScopeDIE));
-    InlinedSPNodes.push_back(InlinedSP);
-  } else
-    I->second.push_back(std::make_pair(StartLabel, ScopeDIE));
-
+  // Add the call site information to the DIE.
   DILocation DL(Scope->getInlinedAt());
-  TheCU->addUInt(ScopeDIE, dwarf::DW_AT_call_file, 0,
+  TheCU->addUInt(ScopeDIE, dwarf::DW_AT_call_file, None,
                  getOrCreateSourceID(DL.getFilename(), DL.getDirectory(),
                                      TheCU->getUniqueID()));
-  TheCU->addUInt(ScopeDIE, dwarf::DW_AT_call_line, 0, DL.getLineNumber());
+  TheCU->addUInt(ScopeDIE, dwarf::DW_AT_call_line, None, DL.getLineNumber());
 
   // Add name to the name table, we do this here because we're guaranteed
   // to have concrete versions of our DW_TAG_inlined_subprogram nodes.
@@ -551,42 +574,49 @@ DIE *DwarfDebug::constructInlinedScopeDIE(CompileUnit *TheCU,
   return ScopeDIE;
 }
 
-// Construct a DIE for this scope.
-DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
-  if (!Scope || !Scope->getScopeNode())
-    return NULL;
-
-  DIScope DS(Scope->getScopeNode());
-  // Early return to avoid creating dangling variable|scope DIEs.
-  if (!Scope->getInlinedAt() && DS.isSubprogram() && Scope->isAbstractScope() &&
-      !TheCU->getDIE(DS))
-    return NULL;
-
-  SmallVector<DIE *, 8> Children;
-  DIE *ObjectPointer = NULL;
+DIE *DwarfDebug::createScopeChildrenDIE(CompileUnit *TheCU, LexicalScope *Scope,
+                                        SmallVectorImpl<DIE*> &Children) {
+    DIE *ObjectPointer = NULL;
 
   // Collect arguments for current function.
   if (LScopes.isCurrentFunctionScope(Scope))
     for (unsigned i = 0, N = CurrentFnArguments.size(); i < N; ++i)
       if (DbgVariable *ArgDV = CurrentFnArguments[i])
         if (DIE *Arg =
-            TheCU->constructVariableDIE(ArgDV, Scope->isAbstractScope())) {
+            TheCU->constructVariableDIE(*ArgDV, Scope->isAbstractScope())) {
           Children.push_back(Arg);
           if (ArgDV->isObjectPointer()) ObjectPointer = Arg;
         }
 
   // Collect lexical scope children first.
-  const SmallVector<DbgVariable *, 8> &Variables = ScopeVariables.lookup(Scope);
+  const SmallVectorImpl<DbgVariable *> &Variables =ScopeVariables.lookup(Scope);
   for (unsigned i = 0, N = Variables.size(); i < N; ++i)
     if (DIE *Variable =
-        TheCU->constructVariableDIE(Variables[i], Scope->isAbstractScope())) {
+        TheCU->constructVariableDIE(*Variables[i], Scope->isAbstractScope())) {
       Children.push_back(Variable);
       if (Variables[i]->isObjectPointer()) ObjectPointer = Variable;
     }
-  const SmallVector<LexicalScope *, 4> &Scopes = Scope->getChildren();
+  const SmallVectorImpl<LexicalScope *> &Scopes = Scope->getChildren();
   for (unsigned j = 0, M = Scopes.size(); j < M; ++j)
     if (DIE *Nested = constructScopeDIE(TheCU, Scopes[j]))
       Children.push_back(Nested);
+  return ObjectPointer;
+}
+
+// Construct a DIE for this scope.
+DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
+  if (!Scope || !Scope->getScopeNode())
+    return NULL;
+
+  DIScope DS(Scope->getScopeNode());
+
+  SmallVector<DIE *, 8> Children;
+  DIE *ObjectPointer = NULL;
+  bool ChildrenCreated = false;
+
+  // We try to create the scope DIE first, then the children DIEs. This will
+  // avoid creating un-used children then removing them later when we find out
+  // the scope DIE is null.
   DIE *ScopeDIE = NULL;
   if (Scope->getInlinedAt())
     ScopeDIE = constructInlinedScopeDIE(TheCU, Scope);
@@ -597,34 +627,49 @@ DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
       // Note down abstract DIE.
       if (ScopeDIE)
         AbstractSPDies.insert(std::make_pair(DS, ScopeDIE));
-    }
-    else
-      ScopeDIE = updateSubprogramScopeDIE(TheCU, DS);
-  }
-  else {
+    } else
+      ScopeDIE = updateSubprogramScopeDIE(TheCU, DISubprogram(DS));
+  } else {
+    // Early exit when we know the scope DIE is going to be null.
+    if (isLexicalScopeDIENull(Scope))
+      return NULL;
+
+    // We create children here when we know the scope DIE is not going to be
+    // null and the children will be added to the scope DIE.
+    ObjectPointer = createScopeChildrenDIE(TheCU, Scope, Children);
+    ChildrenCreated = true;
+
     // There is no need to emit empty lexical block DIE.
     std::pair<ImportedEntityMap::const_iterator,
               ImportedEntityMap::const_iterator> Range = std::equal_range(
         ScopesWithImportedEntities.begin(), ScopesWithImportedEntities.end(),
         std::pair<const MDNode *, const MDNode *>(DS, (const MDNode*)0),
-        CompareFirst());
+        less_first());
     if (Children.empty() && Range.first == Range.second)
       return NULL;
     ScopeDIE = constructLexicalScopeDIE(TheCU, Scope);
-    for (ImportedEntityMap::const_iterator i = Range.first; i != Range.second; ++i)
-      constructImportedModuleDIE(TheCU, i->second, ScopeDIE);
+    assert(ScopeDIE && "Scope DIE should not be null.");
+    for (ImportedEntityMap::const_iterator i = Range.first; i != Range.second;
+         ++i)
+      constructImportedEntityDIE(TheCU, i->second, ScopeDIE);
   }
 
-  if (!ScopeDIE) return NULL;
+  if (!ScopeDIE) {
+    assert(Children.empty() &&
+           "We create children only when the scope DIE is not null.");
+    return NULL;
+  }
+  if (!ChildrenCreated)
+    // We create children when the scope DIE is not null.
+    ObjectPointer = createScopeChildrenDIE(TheCU, Scope, Children);
 
   // Add children
-  for (SmallVector<DIE *, 8>::iterator I = Children.begin(),
+  for (SmallVectorImpl<DIE *>::iterator I = Children.begin(),
          E = Children.end(); I != E; ++I)
     ScopeDIE->addChild(*I);
 
   if (DS.isSubprogram() && ObjectPointer != NULL)
-    TheCU->addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer,
-                       dwarf::DW_FORM_ref4, ObjectPointer);
+    TheCU->addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, ObjectPointer);
 
   if (DS.isSubprogram())
     TheCU->addPubTypes(DISubprogram(DS));
@@ -640,8 +685,10 @@ unsigned DwarfDebug::getOrCreateSourceID(StringRef FileName,
                                          StringRef DirName, unsigned CUID) {
   // If we use .loc in assembly, we can't separate .file entries according to
   // compile units. Thus all files will belong to the default compile unit.
-  if (Asm->TM.hasMCUseLoc() &&
-      Asm->OutStreamer.getKind() == MCStreamer::SK_AsmStreamer)
+
+  // FIXME: add a better feature test than hasRawTextSupport. Even better,
+  // extend .file to support this.
+  if (Asm->TM.hasMCUseLoc() && Asm->OutStreamer.hasRawTextSupport())
     CUID = 0;
 
   // If FE did not provide a file name, then assume stdin.
@@ -676,14 +723,12 @@ unsigned DwarfDebug::getOrCreateSourceID(StringRef FileName,
 
 // Create new CompileUnit for the given metadata node with tag
 // DW_TAG_compile_unit.
-CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
-  DICompileUnit DIUnit(N);
+CompileUnit *DwarfDebug::constructCompileUnit(DICompileUnit DIUnit) {
   StringRef FN = DIUnit.getFilename();
   CompilationDir = DIUnit.getDirectory();
 
   DIE *Die = new DIE(dwarf::DW_TAG_compile_unit);
-  CompileUnit *NewCU = new CompileUnit(GlobalCUIndexCount++,
-                                       DIUnit.getLanguage(), Die, Asm,
+  CompileUnit *NewCU = new CompileUnit(GlobalCUIndexCount++, Die, DIUnit, Asm,
                                        this, &InfoHolder);
 
   FileIDCUMap[NewCU->getUniqueID()] = 0;
@@ -710,31 +755,56 @@ CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
 
   // Use a single line table if we are using .loc and generating assembly.
   bool UseTheFirstCU =
-    (Asm->TM.hasMCUseLoc() &&
-     Asm->OutStreamer.getKind() == MCStreamer::SK_AsmStreamer) ||
-    (NewCU->getUniqueID() == 0);
+      (Asm->TM.hasMCUseLoc() && Asm->OutStreamer.hasRawTextSupport()) ||
+      (NewCU->getUniqueID() == 0);
 
-  // DW_AT_stmt_list is a offset of line number information for this
-  // compile unit in debug_line section. For split dwarf this is
-  // left in the skeleton CU and so not included.
-  // The line table entries are not always emitted in assembly, so it
-  // is not okay to use line_table_start here.
   if (!useSplitDwarf()) {
+    // DW_AT_stmt_list is a offset of line number information for this
+    // compile unit in debug_line section. For split dwarf this is
+    // left in the skeleton CU and so not included.
+    // The line table entries are not always emitted in assembly, so it
+    // is not okay to use line_table_start here.
     if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
-      NewCU->addLabel(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4,
-                      UseTheFirstCU ?
-                      Asm->GetTempSymbol("section_line") : LineTableStartSym);
+      NewCU->addSectionLabel(
+          Die, dwarf::DW_AT_stmt_list,
+          UseTheFirstCU ? Asm->GetTempSymbol("section_line")
+                        : LineTableStartSym);
     else if (UseTheFirstCU)
-      NewCU->addUInt(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4, 0);
+      NewCU->addSectionOffset(Die, dwarf::DW_AT_stmt_list, 0);
     else
-      NewCU->addDelta(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4,
-                      LineTableStartSym, DwarfLineSectionSym);
+      NewCU->addSectionDelta(Die, dwarf::DW_AT_stmt_list,
+                             LineTableStartSym, DwarfLineSectionSym);
+
+    // If we're using split dwarf the compilation dir is going to be in the
+    // skeleton CU and so we don't need to duplicate it here.
+    if (!CompilationDir.empty())
+      NewCU->addString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
+
+    // Flags to let the linker know we have emitted new style pubnames. Only
+    // emit it here if we don't have a skeleton CU for split dwarf.
+    if (GenerateGnuPubSections) {
+      if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+        NewCU->addSectionLabel(
+            Die, dwarf::DW_AT_GNU_pubnames,
+            Asm->GetTempSymbol("gnu_pubnames", NewCU->getUniqueID()));
+      else
+        NewCU->addSectionDelta(
+            Die, dwarf::DW_AT_GNU_pubnames,
+            Asm->GetTempSymbol("gnu_pubnames", NewCU->getUniqueID()),
+            DwarfGnuPubNamesSectionSym);
+
+      if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+        NewCU->addSectionLabel(
+            Die, dwarf::DW_AT_GNU_pubtypes,
+            Asm->GetTempSymbol("gnu_pubtypes", NewCU->getUniqueID()));
+      else
+        NewCU->addSectionDelta(
+            Die, dwarf::DW_AT_GNU_pubtypes,
+            Asm->GetTempSymbol("gnu_pubtypes", NewCU->getUniqueID()),
+            DwarfGnuPubTypesSectionSym);
+    }
   }
 
-  // If we're using split dwarf the compilation dir is going to be in the
-  // skeleton CU and so we don't need to duplicate it here.
-  if (!useSplitDwarf() && !CompilationDir.empty())
-    NewCU->addString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
   if (DIUnit.isOptimized())
     NewCU->addFlag(Die, dwarf::DW_AT_APPLE_optimized);
 
@@ -751,13 +821,17 @@ CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
 
   InfoHolder.addUnit(NewCU);
 
-  CUMap.insert(std::make_pair(N, NewCU));
+  CUMap.insert(std::make_pair(DIUnit, NewCU));
+  CUDieMap.insert(std::make_pair(Die, NewCU));
   return NewCU;
 }
 
 // Construct subprogram DIE.
-void DwarfDebug::constructSubprogramDIE(CompileUnit *TheCU,
-                                        const MDNode *N) {
+void DwarfDebug::constructSubprogramDIE(CompileUnit *TheCU, const MDNode *N) {
+  // FIXME: We should only call this routine once, however, during LTO if a
+  // program is defined in multiple CUs we could end up calling it out of
+  // beginModule as we walk the CUs.
+
   CompileUnit *&CURef = SPMap[N];
   if (CURef)
     return;
@@ -771,49 +845,54 @@ void DwarfDebug::constructSubprogramDIE(CompileUnit *TheCU,
 
   DIE *SubprogramDie = TheCU->getOrCreateSubprogramDIE(SP);
 
-  // Add to map.
-  TheCU->insertDIE(N, SubprogramDie);
-
-  // Add to context owner.
-  TheCU->addToContextOwner(SubprogramDie, SP.getContext());
-
-  // Expose as global, if requested.
-  if (GenerateDwarfPubNamesSection)
-    TheCU->addGlobalName(SP.getName(), SubprogramDie);
+  // Expose as a global name.
+  TheCU->addGlobalName(SP.getName(), SubprogramDie, resolve(SP.getContext()));
 }
 
-void DwarfDebug::constructImportedModuleDIE(CompileUnit *TheCU,
+void DwarfDebug::constructImportedEntityDIE(CompileUnit *TheCU,
                                             const MDNode *N) {
-  DIImportedModule Module(N);
+  DIImportedEntity Module(N);
   if (!Module.Verify())
     return;
   if (DIE *D = TheCU->getOrCreateContextDIE(Module.getContext()))
-    constructImportedModuleDIE(TheCU, Module, D);
+    constructImportedEntityDIE(TheCU, Module, D);
 }
 
-void DwarfDebug::constructImportedModuleDIE(CompileUnit *TheCU, const MDNode *N,
+void DwarfDebug::constructImportedEntityDIE(CompileUnit *TheCU, const MDNode *N,
                                             DIE *Context) {
-  DIImportedModule Module(N);
+  DIImportedEntity Module(N);
   if (!Module.Verify())
     return;
-  return constructImportedModuleDIE(TheCU, Module, Context);
+  return constructImportedEntityDIE(TheCU, Module, Context);
 }
 
-void DwarfDebug::constructImportedModuleDIE(CompileUnit *TheCU,
-                                            const DIImportedModule &Module,
+void DwarfDebug::constructImportedEntityDIE(CompileUnit *TheCU,
+                                            const DIImportedEntity &Module,
                                             DIE *Context) {
   assert(Module.Verify() &&
          "Use one of the MDNode * overloads to handle invalid metadata");
   assert(Context && "Should always have a context for an imported_module");
-  DIE *IMDie = new DIE(dwarf::DW_TAG_imported_module);
+  DIE *IMDie = new DIE(Module.getTag());
   TheCU->insertDIE(Module, IMDie);
-  DIE *NSDie = TheCU->getOrCreateNameSpace(Module.getNameSpace());
+  DIE *EntityDie;
+  DIDescriptor Entity = Module.getEntity();
+  if (Entity.isNameSpace())
+    EntityDie = TheCU->getOrCreateNameSpace(DINameSpace(Entity));
+  else if (Entity.isSubprogram())
+    EntityDie = TheCU->getOrCreateSubprogramDIE(DISubprogram(Entity));
+  else if (Entity.isType())
+    EntityDie = TheCU->getOrCreateTypeDIE(DIType(Entity));
+  else
+    EntityDie = TheCU->getDIE(Entity);
   unsigned FileID = getOrCreateSourceID(Module.getContext().getFilename(),
                                         Module.getContext().getDirectory(),
                                         TheCU->getUniqueID());
-  TheCU->addUInt(IMDie, dwarf::DW_AT_decl_file, 0, FileID);
-  TheCU->addUInt(IMDie, dwarf::DW_AT_decl_line, 0, Module.getLineNumber());
-  TheCU->addDIEEntry(IMDie, dwarf::DW_AT_import, dwarf::DW_FORM_ref4, NSDie);
+  TheCU->addUInt(IMDie, dwarf::DW_AT_decl_file, None, FileID);
+  TheCU->addUInt(IMDie, dwarf::DW_AT_decl_line, None, Module.getLineNumber());
+  TheCU->addDIEEntry(IMDie, dwarf::DW_AT_import, EntityDie);
+  StringRef Name = Module.getName();
+  if (!Name.empty())
+    TheCU->addString(IMDie, dwarf::DW_AT_name, Name);
   Context->addChild(IMDie);
 }
 
@@ -831,6 +910,7 @@ void DwarfDebug::beginModule() {
   NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
   if (!CU_Nodes)
     return;
+  TypeIdentifierMap = generateDITypeIdentifierMap(CU_Nodes);
 
   // Emit initial sections so we can reference labels later.
   emitSectionLabels();
@@ -838,16 +918,16 @@ void DwarfDebug::beginModule() {
   for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
     DICompileUnit CUNode(CU_Nodes->getOperand(i));
     CompileUnit *CU = constructCompileUnit(CUNode);
-    DIArray ImportedModules = CUNode.getImportedModules();
-    for (unsigned i = 0, e = ImportedModules.getNumElements(); i != e; ++i)
+    DIArray ImportedEntities = CUNode.getImportedEntities();
+    for (unsigned i = 0, e = ImportedEntities.getNumElements(); i != e; ++i)
       ScopesWithImportedEntities.push_back(std::make_pair(
-          DIImportedModule(ImportedModules.getElement(i)).getContext(),
-          ImportedModules.getElement(i)));
+          DIImportedEntity(ImportedEntities.getElement(i)).getContext(),
+          ImportedEntities.getElement(i)));
     std::sort(ScopesWithImportedEntities.begin(),
-              ScopesWithImportedEntities.end(), CompareFirst());
+              ScopesWithImportedEntities.end(), less_first());
     DIArray GVs = CUNode.getGlobalVariables();
     for (unsigned i = 0, e = GVs.getNumElements(); i != e; ++i)
-      CU->createGlobalVariableDIE(GVs.getElement(i));
+      CU->createGlobalVariableDIE(DIGlobalVariable(GVs.getElement(i)));
     DIArray SPs = CUNode.getSubprograms();
     for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i)
       constructSubprogramDIE(CU, SPs.getElement(i));
@@ -859,24 +939,15 @@ void DwarfDebug::beginModule() {
       CU->getOrCreateTypeDIE(RetainedTypes.getElement(i));
     // Emit imported_modules last so that the relevant context is already
     // available.
-    for (unsigned i = 0, e = ImportedModules.getNumElements(); i != e; ++i)
-      constructImportedModuleDIE(CU, ImportedModules.getElement(i));
-    // If we're splitting the dwarf out now that we've got the entire
-    // CU then construct a skeleton CU based upon it.
-    if (useSplitDwarf()) {
-      // This should be a unique identifier when we want to build .dwp files.
-      CU->addUInt(CU->getCUDie(), dwarf::DW_AT_GNU_dwo_id,
-                  dwarf::DW_FORM_data8, 0);
-      // Now construct the skeleton CU associated.
-      constructSkeletonCU(CUNode);
-    }
+    for (unsigned i = 0, e = ImportedEntities.getNumElements(); i != e; ++i)
+      constructImportedEntityDIE(CU, ImportedEntities.getElement(i));
   }
 
   // Tell MMI that we have debug info.
   MMI->setDebugInfoAvailability(true);
 
   // Prime section data.
-  SectionMap.insert(Asm->getObjFileLowering().getTextSection());
+  SectionMap[Asm->getObjFileLowering().getTextSection()];
 }
 
 // Attach DW_AT_inline attribute with inlined subprogram DIEs.
@@ -885,21 +956,20 @@ void DwarfDebug::computeInlinedDIEs() {
   for (SmallPtrSet<DIE *, 4>::iterator AI = InlinedSubprogramDIEs.begin(),
          AE = InlinedSubprogramDIEs.end(); AI != AE; ++AI) {
     DIE *ISP = *AI;
-    FirstCU->addUInt(ISP, dwarf::DW_AT_inline, 0, dwarf::DW_INL_inlined);
+    FirstCU->addUInt(ISP, dwarf::DW_AT_inline, None, dwarf::DW_INL_inlined);
   }
   for (DenseMap<const MDNode *, DIE *>::iterator AI = AbstractSPDies.begin(),
          AE = AbstractSPDies.end(); AI != AE; ++AI) {
     DIE *ISP = AI->second;
     if (InlinedSubprogramDIEs.count(ISP))
       continue;
-    FirstCU->addUInt(ISP, dwarf::DW_AT_inline, 0, dwarf::DW_INL_inlined);
+    FirstCU->addUInt(ISP, dwarf::DW_AT_inline, None, dwarf::DW_INL_inlined);
   }
 }
 
 // Collect info for variables that were optimized out.
 void DwarfDebug::collectDeadVariables() {
   const Module *M = MMI->getModule();
-  DenseMap<const MDNode *, LexicalScope *> DeadFnScopeMap;
 
   if (NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu")) {
     for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
@@ -907,33 +977,70 @@ void DwarfDebug::collectDeadVariables() {
       DIArray Subprograms = TheCU.getSubprograms();
       for (unsigned i = 0, e = Subprograms.getNumElements(); i != e; ++i) {
         DISubprogram SP(Subprograms.getElement(i));
-        if (ProcessedSPNodes.count(SP) != 0) continue;
-        if (!SP.Verify()) continue;
-        if (!SP.isDefinition()) continue;
+        if (ProcessedSPNodes.count(SP) != 0)
+          continue;
+        if (!SP.isSubprogram())
+          continue;
+        if (!SP.isDefinition())
+          continue;
         DIArray Variables = SP.getVariables();
-        if (Variables.getNumElements() == 0) continue;
-
-        LexicalScope *Scope =
-          new LexicalScope(NULL, DIDescriptor(SP), NULL, false);
-        DeadFnScopeMap[SP] = Scope;
+        if (Variables.getNumElements() == 0)
+          continue;
 
         // Construct subprogram DIE and add variables DIEs.
         CompileUnit *SPCU = CUMap.lookup(TheCU);
         assert(SPCU && "Unable to find Compile Unit!");
+        // FIXME: See the comment in constructSubprogramDIE about duplicate
+        // subprogram DIEs.
         constructSubprogramDIE(SPCU, SP);
-        DIE *ScopeDIE = SPCU->getDIE(SP);
+        DIE *SPDIE = SPCU->getDIE(SP);
         for (unsigned vi = 0, ve = Variables.getNumElements(); vi != ve; ++vi) {
           DIVariable DV(Variables.getElement(vi));
-          if (!DV.Verify()) continue;
-          DbgVariable *NewVar = new DbgVariable(DV, NULL);
+          if (!DV.isVariable())
+            continue;
+          DbgVariable NewVar(DV, NULL, this);
           if (DIE *VariableDIE =
-              SPCU->constructVariableDIE(NewVar, Scope->isAbstractScope()))
-            ScopeDIE->addChild(VariableDIE);
+                  SPCU->constructVariableDIE(NewVar, false))
+            SPDIE->addChild(VariableDIE);
         }
       }
     }
   }
-  DeleteContainerSeconds(DeadFnScopeMap);
+}
+
+// Type Signature [7.27] and ODR Hash code.
+
+/// \brief Grabs the string in whichever attribute is passed in and returns
+/// a reference to it. Returns "" if the attribute doesn't exist.
+static StringRef getDIEStringAttr(DIE *Die, unsigned Attr) {
+  DIEValue *V = Die->findAttribute(Attr);
+
+  if (DIEString *S = dyn_cast_or_null<DIEString>(V))
+    return S->getString();
+
+  return StringRef("");
+}
+
+/// Return true if the current DIE is contained within an anonymous namespace.
+static bool isContainedInAnonNamespace(DIE *Die) {
+  DIE *Parent = Die->getParent();
+
+  while (Parent) {
+    if (Parent->getTag() == dwarf::DW_TAG_namespace &&
+        getDIEStringAttr(Parent, dwarf::DW_AT_name) == "")
+      return true;
+    Parent = Parent->getParent();
+  }
+
+  return false;
+}
+
+/// Test if the current CU language is C++ and that we have
+/// a named type that is not contained in an anonymous namespace.
+static bool shouldAddODRHash(CompileUnit *CU, DIE *Die) {
+  return CU->getLanguage() == dwarf::DW_LANG_C_plus_plus &&
+         getDIEStringAttr(Die, dwarf::DW_AT_name) != "" &&
+         !isContainedInAnonNamespace(Die);
 }
 
 void DwarfDebug::finalizeModuleInfo() {
@@ -943,31 +1050,102 @@ void DwarfDebug::finalizeModuleInfo() {
   // Attach DW_AT_inline attribute with inlined subprogram DIEs.
   computeInlinedDIEs();
 
-  // Emit DW_AT_containing_type attribute to connect types with their
-  // vtable holding type.
+  // Split out type units and conditionally add an ODR tag to the split
+  // out type.
+  // FIXME: Do type splitting.
+  for (unsigned i = 0, e = TypeUnits.size(); i != e; ++i) {
+    DIE *Die = TypeUnits[i];
+    DIEHash Hash;
+    // If we've requested ODR hashes and it's applicable for an ODR hash then
+    // add the ODR signature now.
+    // FIXME: This should be added onto the type unit, not the type, but this
+    // works as an intermediate stage.
+    if (GenerateODRHash && shouldAddODRHash(CUMap.begin()->second, Die))
+      CUMap.begin()->second->addUInt(Die, dwarf::DW_AT_GNU_odr_signature,
+                                     dwarf::DW_FORM_data8,
+                                     Hash.computeDIEODRSignature(*Die));
+  }
+
+  // Handle anything that needs to be done on a per-cu basis.
   for (DenseMap<const MDNode *, CompileUnit *>::iterator CUI = CUMap.begin(),
-         CUE = CUMap.end(); CUI != CUE; ++CUI) {
+                                                         CUE = CUMap.end();
+       CUI != CUE; ++CUI) {
     CompileUnit *TheCU = CUI->second;
+    // Emit DW_AT_containing_type attribute to connect types with their
+    // vtable holding type.
     TheCU->constructContainingTypeDIEs();
+
+    // If we're splitting the dwarf out now that we've got the entire
+    // CU then construct a skeleton CU based upon it.
+    if (useSplitDwarf()) {
+      uint64_t ID = 0;
+      if (GenerateCUHash) {
+        DIEHash CUHash;
+        ID = CUHash.computeCUSignature(*TheCU->getCUDie());
+      }
+      // This should be a unique identifier when we want to build .dwp files.
+      TheCU->addUInt(TheCU->getCUDie(), dwarf::DW_AT_GNU_dwo_id,
+                     dwarf::DW_FORM_data8, ID);
+      // Now construct the skeleton CU associated.
+      CompileUnit *SkCU = constructSkeletonCU(TheCU);
+      // This should be a unique identifier when we want to build .dwp files.
+      SkCU->addUInt(SkCU->getCUDie(), dwarf::DW_AT_GNU_dwo_id,
+                    dwarf::DW_FORM_data8, ID);
+    }
   }
 
-   // Compute DIE offsets and sizes.
+  // Compute DIE offsets and sizes.
   InfoHolder.computeSizeAndOffsets();
   if (useSplitDwarf())
     SkeletonHolder.computeSizeAndOffsets();
 }
 
 void DwarfDebug::endSections() {
-  // Standard sections final addresses.
-  Asm->OutStreamer.SwitchSection(Asm->getObjFileLowering().getTextSection());
-  Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("text_end"));
-  Asm->OutStreamer.SwitchSection(Asm->getObjFileLowering().getDataSection());
-  Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("data_end"));
+   // Filter labels by section.
+  for (size_t n = 0; n < ArangeLabels.size(); n++) {
+    const SymbolCU &SCU = ArangeLabels[n];
+    if (SCU.Sym->isInSection()) {
+      // Make a note of this symbol and it's section.
+      const MCSection *Section = &SCU.Sym->getSection();
+      if (!Section->getKind().isMetadata())
+        SectionMap[Section].push_back(SCU);
+    } else {
+      // Some symbols (e.g. common/bss on mach-o) can have no section but still
+      // appear in the output. This sucks as we rely on sections to build
+      // arange spans. We can do it without, but it's icky.
+      SectionMap[NULL].push_back(SCU);
+    }
+  }
 
-  // End text sections.
-  for (unsigned I = 0, E = SectionMap.size(); I != E; ++I) {
-    Asm->OutStreamer.SwitchSection(SectionMap[I]);
-    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("section_end", I+1));
+  // Build a list of sections used.
+  std::vector<const MCSection *> Sections;
+  for (SectionMapType::iterator it = SectionMap.begin(); it != SectionMap.end();
+       it++) {
+    const MCSection *Section = it->first;
+    Sections.push_back(Section);
+  }
+
+  // Sort the sections into order.
+  // This is only done to ensure consistent output order across different runs.
+  std::sort(Sections.begin(), Sections.end(), SectionSort);
+
+  // Add terminating symbols for each section.
+  for (unsigned ID=0;ID<Sections.size();ID++) {
+    const MCSection *Section = Sections[ID];
+    MCSymbol *Sym = NULL;
+
+    if (Section) {
+      // We can't call MCSection::getLabelEndName, as it's only safe to do so
+      // if we know the section name up-front. For user-created sections, the resulting
+      // label may not be valid to use as a label. (section names can use a greater
+      // set of characters on some systems)
+      Sym = Asm->GetTempSymbol("debug_end", ID);
+      Asm->OutStreamer.SwitchSection(Section);
+      Asm->OutStreamer.EmitLabel(Sym);
+    }
+
+    // Insert a final terminator.
+    SectionMap[Section].push_back(SymbolCU(NULL, Sym));
   }
 }
 
@@ -984,6 +1162,8 @@ void DwarfDebug::endModule() {
   finalizeModuleInfo();
 
   if (!useSplitDwarf()) {
+    emitDebugStr();
+
     // Emit all the DIEs into a debug info section.
     emitDebugInfo();
 
@@ -1002,15 +1182,12 @@ void DwarfDebug::endModule() {
     // Emit info into a debug macinfo section.
     emitDebugMacInfo();
 
-    // Emit inline info.
-    // TODO: When we don't need the option anymore we
-    // can remove all of the code that this section
-    // depends upon.
-    if (useDarwinGDBCompat())
-      emitDebugInlineInfo();
   } else {
     // TODO: Fill this in for separated debug sections and separate
     // out information into new sections.
+    emitDebugStr();
+    if (useSplitDwarf())
+      emitDebugStrDWO();
 
     // Emit the debug info section and compile units.
     emitDebugInfo();
@@ -1035,12 +1212,6 @@ void DwarfDebug::endModule() {
     // Emit DWO addresses.
     InfoHolder.emitAddresses(Asm->getObjFileLowering().getDwarfAddrSection());
 
-    // Emit inline info.
-    // TODO: When we don't need the option anymore we
-    // can remove all of the code that this section
-    // depends upon.
-    if (useDarwinGDBCompat())
-      emitDebugInlineInfo();
   }
 
   // Emit info into the dwarf accelerator table sections.
@@ -1051,20 +1222,11 @@ void DwarfDebug::endModule() {
     emitAccelTypes();
   }
 
-  // Emit info into a debug pubnames section, if requested.
-  if (GenerateDwarfPubNamesSection)
-    emitDebugPubnames();
-
-  // Emit info into a debug pubtypes section.
-  // TODO: When we don't need the option anymore we can
-  // remove all of the code that adds to the table.
-  if (useDarwinGDBCompat())
-    emitDebugPubTypes();
-
-  // Finally emit string information into a string table.
-  emitDebugStr();
-  if (useSplitDwarf())
-    emitDebugStrDWO();
+  // Emit the pubnames and pubtypes sections if requested.
+  if (HasDwarfPubSections) {
+    emitDebugPubNames(GenerateGnuPubSections);
+    emitDebugPubTypes(GenerateGnuPubSections);
+  }
 
   // clean up.
   SPMap.clear();
@@ -1072,7 +1234,7 @@ void DwarfDebug::endModule() {
          E = CUMap.end(); I != E; ++I)
     delete I->second;
 
-  for (SmallVector<CompileUnit *, 1>::iterator I = SkeletonCUs.begin(),
+  for (SmallVectorImpl<CompileUnit *>::iterator I = SkeletonCUs.begin(),
          E = SkeletonCUs.end(); I != E; ++I)
     delete *I;
 
@@ -1094,7 +1256,7 @@ DbgVariable *DwarfDebug::findAbstractVariable(DIVariable &DV,
   if (!Scope)
     return NULL;
 
-  AbsDbgVariable = new DbgVariable(Var, NULL);
+  AbsDbgVariable = new DbgVariable(Var, NULL, this);
   addScopeVariable(Scope, AbsDbgVariable);
   AbstractVariables[Var] = AbsDbgVariable;
   return AbsDbgVariable;
@@ -1143,7 +1305,7 @@ DwarfDebug::collectVariableInfoFromMMITable(const MachineFunction *MF,
       continue;
 
     DbgVariable *AbsDbgVariable = findAbstractVariable(DV, VP.second);
-    DbgVariable *RegVar = new DbgVariable(DV, AbsDbgVariable);
+    DbgVariable *RegVar = new DbgVariable(DV, AbsDbgVariable, this);
     RegVar->setFrameIndex(VP.first);
     if (!addCurrentFnArgument(MF, RegVar, Scope))
       addScopeVariable(Scope, RegVar);
@@ -1158,7 +1320,8 @@ static bool isDbgValueInDefinedReg(const MachineInstr *MI) {
   assert(MI->isDebugValue() && "Invalid DBG_VALUE machine instruction!");
   return MI->getNumOperands() == 3 &&
          MI->getOperand(0).isReg() && MI->getOperand(0).getReg() &&
-         MI->getOperand(1).isImm() && MI->getOperand(1).getImm() == 0;
+         (MI->getOperand(1).isImm() ||
+          (MI->getOperand(1).isReg() && MI->getOperand(1).getReg() == 0U));
 }
 
 // Get .debug_loc entry for the instruction range starting at MI.
@@ -1168,16 +1331,12 @@ static DotDebugLocEntry getDebugLocEntry(AsmPrinter *Asm,
                                          const MachineInstr *MI) {
   const MDNode *Var =  MI->getOperand(MI->getNumOperands() - 1).getMetadata();
 
-  if (MI->getNumOperands() != 3) {
-    MachineLocation MLoc = Asm->getDebugValueLocation(MI);
-    return DotDebugLocEntry(FLabel, SLabel, MLoc, Var);
-  }
-  if (MI->getOperand(0).isReg() && MI->getOperand(1).isImm()) {
+  assert(MI->getNumOperands() == 3);
+  if (MI->getOperand(0).isReg()) {
     MachineLocation MLoc;
-    // TODO: Currently an offset of 0 in a DBG_VALUE means
-    // we need to generate a direct register value.
-    // There is no way to specify an indirect value with offset 0.
-    if (MI->getOperand(1).getImm() == 0)
+    // If the second operand is an immediate, this is a
+    // register-indirect address.
+    if (!MI->getOperand(1).isImm())
       MLoc.set(MI->getOperand(0).getReg());
     else
       MLoc.set(MI->getOperand(0).getReg(), MI->getOperand(1).getImm());
@@ -1198,7 +1357,7 @@ void
 DwarfDebug::collectVariableInfo(const MachineFunction *MF,
                                 SmallPtrSet<const MDNode *, 16> &Processed) {
 
-  // collection info from MMI table.
+  // Grab the variable info that was squirreled away in the MMI side-table.
   collectVariableInfoFromMMITable(MF, Processed);
 
   for (SmallVectorImpl<const MDNode*>::const_iterator
@@ -1231,7 +1390,7 @@ DwarfDebug::collectVariableInfo(const MachineFunction *MF,
     Processed.insert(DV);
     assert(MInsn->isDebugValue() && "History must begin with debug value");
     DbgVariable *AbsVar = findAbstractVariable(DV, MInsn->getDebugLoc());
-    DbgVariable *RegVar = new DbgVariable(DV, AbsVar);
+    DbgVariable *RegVar = new DbgVariable(DV, AbsVar, this);
     if (!addCurrentFnArgument(MF, RegVar, Scope))
       addScopeVariable(Scope, RegVar);
     if (AbsVar)
@@ -1291,10 +1450,10 @@ DwarfDebug::collectVariableInfo(const MachineFunction *MF,
   DIArray Variables = DISubprogram(FnScope->getScopeNode()).getVariables();
   for (unsigned i = 0, e = Variables.getNumElements(); i != e; ++i) {
     DIVariable DV(Variables.getElement(i));
-    if (!DV || !DV.Verify() || !Processed.insert(DV))
+    if (!DV || !DV.isVariable() || !Processed.insert(DV))
       continue;
     if (LexicalScope *Scope = LScopes.findLexicalScope(DV.getContext()))
-      addScopeVariable(Scope, new DbgVariable(DV, NULL));
+      addScopeVariable(Scope, new DbgVariable(DV, NULL, this));
   }
 }
 
@@ -1388,19 +1547,19 @@ void DwarfDebug::identifyScopeMarkers() {
   while (!WorkList.empty()) {
     LexicalScope *S = WorkList.pop_back_val();
 
-    const SmallVector<LexicalScope *, 4> &Children = S->getChildren();
+    const SmallVectorImpl<LexicalScope *> &Children = S->getChildren();
     if (!Children.empty())
-      for (SmallVector<LexicalScope *, 4>::const_iterator SI = Children.begin(),
+      for (SmallVectorImpl<LexicalScope *>::const_iterator SI = Children.begin(),
              SE = Children.end(); SI != SE; ++SI)
         WorkList.push_back(*SI);
 
     if (S->isAbstractScope())
       continue;
 
-    const SmallVector<InsnRange, 4> &Ranges = S->getRanges();
+    const SmallVectorImpl<InsnRange> &Ranges = S->getRanges();
     if (Ranges.empty())
       continue;
-    for (SmallVector<InsnRange, 4>::const_iterator RI = Ranges.begin(),
+    for (SmallVectorImpl<InsnRange>::const_iterator RI = Ranges.begin(),
            RE = Ranges.end(); RI != RE; ++RI) {
       assert(RI->first && "InsnRange does not have first instruction!");
       assert(RI->second && "InsnRange does not have second instruction!");
@@ -1422,7 +1581,7 @@ static MDNode *getScopeNode(DebugLoc DL, const LLVMContext &Ctx) {
 static DebugLoc getFnDebugLoc(DebugLoc DL, const LLVMContext &Ctx) {
   const MDNode *Scope = getScopeNode(DL, Ctx);
   DISubprogram SP = getDISubprogram(Scope);
-  if (SP.Verify()) {
+  if (SP.isSubprogram()) {
     // Check for number of operands since the compatibility is
     // cheap here.
     if (SP->getNumOperands() > 19)
@@ -1437,36 +1596,45 @@ static DebugLoc getFnDebugLoc(DebugLoc DL, const LLVMContext &Ctx) {
 // Gather pre-function debug information.  Assumes being called immediately
 // after the function entry point has been emitted.
 void DwarfDebug::beginFunction(const MachineFunction *MF) {
-  if (!MMI->hasDebugInfo()) return;
+
+  // If there's no debug info for the function we're not going to do anything.
+  if (!MMI->hasDebugInfo())
+    return;
+
+  // Grab the lexical scopes for the function, if we don't have any of those
+  // then we're not going to be able to do anything.
   LScopes.initialize(*MF);
-  if (LScopes.empty()) return;
+  if (LScopes.empty())
+    return;
+
+  assert(UserVariables.empty() && DbgValues.empty() && "Maps weren't cleaned");
+
+  // Make sure that each lexical scope will have a begin/end label.
   identifyScopeMarkers();
 
   // Set DwarfCompileUnitID in MCContext to the Compile Unit this function
-  // belongs to.
+  // belongs to so that we add to the correct per-cu line table in the
+  // non-asm case.
   LexicalScope *FnScope = LScopes.getCurrentFunctionScope();
   CompileUnit *TheCU = SPMap.lookup(FnScope->getScopeNode());
   assert(TheCU && "Unable to find compile unit!");
-  if (Asm->TM.hasMCUseLoc() &&
-      Asm->OutStreamer.getKind() == MCStreamer::SK_AsmStreamer)
+  if (Asm->TM.hasMCUseLoc() && Asm->OutStreamer.hasRawTextSupport())
     // Use a single line table if we are using .loc and generating assembly.
     Asm->OutStreamer.getContext().setDwarfCompileUnitID(0);
   else
     Asm->OutStreamer.getContext().setDwarfCompileUnitID(TheCU->getUniqueID());
 
-  FunctionBeginSym = Asm->GetTempSymbol("func_begin",
-                                        Asm->getFunctionNumber());
+  // Emit a label for the function so that we have a beginning address.
+  FunctionBeginSym = Asm->GetTempSymbol("func_begin", Asm->getFunctionNumber());
   // Assumes in correct section after the entry point.
   Asm->OutStreamer.EmitLabel(FunctionBeginSym);
 
-  assert(UserVariables.empty() && DbgValues.empty() && "Maps weren't cleaned");
-
   const TargetRegisterInfo *TRI = Asm->TM.getRegisterInfo();
   // LiveUserVar - Map physreg numbers to the MDNode they contain.
-  std::vector<const MDNode*> LiveUserVar(TRI->getNumRegs());
+  std::vector<const MDNode *> LiveUserVar(TRI->getNumRegs());
 
-  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
-       I != E; ++I) {
+  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end(); I != E;
+       ++I) {
     bool AtBlockEntry = true;
     for (MachineBasicBlock::const_iterator II = I->begin(), IE = I->end();
          II != IE; ++II) {
@@ -1477,22 +1645,21 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
 
         // Keep track of user variables.
         const MDNode *Var =
-          MI->getOperand(MI->getNumOperands() - 1).getMetadata();
+            MI->getOperand(MI->getNumOperands() - 1).getMetadata();
 
         // Variable is in a register, we need to check for clobbers.
         if (isDbgValueInDefinedReg(MI))
           LiveUserVar[MI->getOperand(0).getReg()] = Var;
 
         // Check the history of this variable.
-        SmallVectorImpl<const MachineInstr*> &History = DbgValues[Var];
+        SmallVectorImpl<const MachineInstr *> &History = DbgValues[Var];
         if (History.empty()) {
           UserVariables.push_back(Var);
           // The first mention of a function argument gets the FunctionBeginSym
           // label, so arguments are visible when breaking at function entry.
           DIVariable DV(Var);
-          if (DV.Verify() && DV.getTag() == dwarf::DW_TAG_arg_variable &&
-              DISubprogram(getDISubprogram(DV.getContext()))
-                .describes(MF->getFunction()))
+          if (DV.isVariable() && DV.getTag() == dwarf::DW_TAG_arg_variable &&
+              getDISubprogram(DV.getContext()).describes(MF->getFunction()))
             LabelsBeforeInsn[MI] = FunctionBeginSym;
         } else {
           // We have seen this variable before. Try to coalesce DBG_VALUEs.
@@ -1502,8 +1669,8 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
             if (History.size() >= 2 &&
                 Prev->isIdenticalTo(History[History.size() - 2])) {
               DEBUG(dbgs() << "Coalescing identical DBG_VALUE entries:\n"
-                    << "\t" << *Prev
-                    << "\t" << *History[History.size() - 2] << "\n");
+                           << "\t" << *Prev << "\t"
+                           << *History[History.size() - 2] << "\n");
               History.pop_back();
             }
 
@@ -1514,17 +1681,15 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
               // Previous register assignment needs to terminate at the end of
               // its basic block.
               MachineBasicBlock::const_iterator LastMI =
-                PrevMBB->getLastNonDebugInstr();
+                  PrevMBB->getLastNonDebugInstr();
               if (LastMI == PrevMBB->end()) {
                 // Drop DBG_VALUE for empty range.
                 DEBUG(dbgs() << "Dropping DBG_VALUE for empty range:\n"
-                      << "\t" << *Prev << "\n");
+                             << "\t" << *Prev << "\n");
                 History.pop_back();
-              }
-              else {
+              } else if (llvm::next(PrevMBB) != PrevMBB->getParent()->end())
                 // Terminate after LastMI.
                 History.push_back(LastMI);
-              }
             }
           }
         }
@@ -1542,11 +1707,12 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
 
         // Check if the instruction clobbers any registers with debug vars.
         for (MachineInstr::const_mop_iterator MOI = MI->operands_begin(),
-               MOE = MI->operands_end(); MOI != MOE; ++MOI) {
+                                              MOE = MI->operands_end();
+             MOI != MOE; ++MOI) {
           if (!MOI->isReg() || !MOI->isDef() || !MOI->getReg())
             continue;
-          for (MCRegAliasIterator AI(MOI->getReg(), TRI, true);
-               AI.isValid(); ++AI) {
+          for (MCRegAliasIterator AI(MOI->getReg(), TRI, true); AI.isValid();
+               ++AI) {
             unsigned Reg = *AI;
             const MDNode *Var = LiveUserVar[Reg];
             if (!Var)
@@ -1558,7 +1724,7 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
             DbgValueHistoryMap::iterator HistI = DbgValues.find(Var);
             if (HistI == DbgValues.end())
               continue;
-            SmallVectorImpl<const MachineInstr*> &History = HistI->second;
+            SmallVectorImpl<const MachineInstr *> &History = HistI->second;
             if (History.empty())
               continue;
             const MachineInstr *Prev = History.back();
@@ -1580,7 +1746,7 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
 
   for (DbgValueHistoryMap::iterator I = DbgValues.begin(), E = DbgValues.end();
        I != E; ++I) {
-    SmallVectorImpl<const MachineInstr*> &History = I->second;
+    SmallVectorImpl<const MachineInstr *> &History = I->second;
     if (History.empty())
       continue;
 
@@ -1589,11 +1755,11 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
     if (Prev->isDebugValue() && isDbgValueInDefinedReg(Prev)) {
       const MachineBasicBlock *PrevMBB = Prev->getParent();
       MachineBasicBlock::const_iterator LastMI =
-        PrevMBB->getLastNonDebugInstr();
+          PrevMBB->getLastNonDebugInstr();
       if (LastMI == PrevMBB->end())
         // Drop DBG_VALUE for empty range.
         History.pop_back();
-      else {
+      else if (PrevMBB != &PrevMBB->getParent()->back()) {
         // Terminate after LastMI.
         History.push_back(LastMI);
       }
@@ -1613,45 +1779,43 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
 
   // Record beginning of function.
   if (!PrologEndLoc.isUnknown()) {
-    DebugLoc FnStartDL = getFnDebugLoc(PrologEndLoc,
-                                       MF->getFunction()->getContext());
-    recordSourceLine(FnStartDL.getLine(), FnStartDL.getCol(),
-                     FnStartDL.getScope(MF->getFunction()->getContext()),
-    // We'd like to list the prologue as "not statements" but GDB behaves
-    // poorly if we do that. Revisit this with caution/GDB (7.5+) testing.
-                     DWARF2_FLAG_IS_STMT);
+    DebugLoc FnStartDL =
+        getFnDebugLoc(PrologEndLoc, MF->getFunction()->getContext());
+    recordSourceLine(
+        FnStartDL.getLine(), FnStartDL.getCol(),
+        FnStartDL.getScope(MF->getFunction()->getContext()),
+        // We'd like to list the prologue as "not statements" but GDB behaves
+        // poorly if we do that. Revisit this with caution/GDB (7.5+) testing.
+        DWARF2_FLAG_IS_STMT);
   }
 }
 
 void DwarfDebug::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
   SmallVectorImpl<DbgVariable *> &Vars = ScopeVariables[LS];
   DIVariable DV = Var->getVariable();
-  if (DV.getTag() == dwarf::DW_TAG_arg_variable) {
-    DISubprogram Ctxt(DV.getContext());
-    DIArray Variables = Ctxt.getVariables();
-    // If the variable is a parameter (arg_variable) and this is an optimized
-    // build (the subprogram has a 'variables' list) make sure we keep the
-    // parameters in order. Otherwise we would produce an incorrect function
-    // type with parameters out of order if function parameters were used out of
-    // order or unused (see the call to addScopeVariable in endFunction where
-    // the remaining unused variables (including parameters) are added).
-    if (unsigned NumVariables = Variables.getNumElements()) {
-      // Keep the parameters at the start of the variables list. Search through
-      // current variable list (Vars) and the full function variable list in
-      // lock-step looking for this parameter in the full list to find the
-      // insertion point.
-      SmallVectorImpl<DbgVariable *>::iterator I = Vars.begin();
-      unsigned j = 0;
-      while (I != Vars.end() && j != NumVariables &&
-             Variables.getElement(j) != DV &&
-             (*I)->getVariable().getTag() == dwarf::DW_TAG_arg_variable) {
-        if (Variables.getElement(j) == (*I)->getVariable())
-          ++I;
-        ++j;
-      }
-      Vars.insert(I, Var);
-      return;
+  // Variables with positive arg numbers are parameters.
+  if (unsigned ArgNum = DV.getArgNumber()) {
+    // Keep all parameters in order at the start of the variable list to ensure
+    // function types are correct (no out-of-order parameters)
+    //
+    // This could be improved by only doing it for optimized builds (unoptimized
+    // builds have the right order to begin with), searching from the back (this
+    // would catch the unoptimized case quickly), or doing a binary search
+    // rather than linear search.
+    SmallVectorImpl<DbgVariable *>::iterator I = Vars.begin();
+    while (I != Vars.end()) {
+      unsigned CurNum = (*I)->getVariable().getArgNumber();
+      // A local (non-parameter) variable has been found, insert immediately
+      // before it.
+      if (CurNum == 0)
+        break;
+      // A later indexed parameter has been found, insert immediately before it.
+      if (CurNum > ArgNum)
+        break;
+      ++I;
     }
+    Vars.insert(I, Var);
+    return;
   }
 
   Vars.push_back(Var);
@@ -1681,12 +1845,12 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
   for (unsigned i = 0, e = AList.size(); i != e; ++i) {
     LexicalScope *AScope = AList[i];
     DISubprogram SP(AScope->getScopeNode());
-    if (SP.Verify()) {
+    if (SP.isSubprogram()) {
       // Collect info for variables that were optimized out.
       DIArray Variables = SP.getVariables();
       for (unsigned i = 0, e = Variables.getNumElements(); i != e; ++i) {
         DIVariable DV(Variables.getElement(i));
-        if (!DV || !DV.Verify() || !ProcessedVars.insert(DV))
+        if (!DV || !DV.isVariable() || !ProcessedVars.insert(DV))
           continue;
         // Check that DbgVariable for DV wasn't created earlier, when
         // findAbstractVariable() was called for inlined instance of DV.
@@ -1695,7 +1859,7 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
         if (AbstractVariables.lookup(CleanDV))
           continue;
         if (LexicalScope *Scope = LScopes.findAbstractScope(DV.getContext()))
-          addScopeVariable(Scope, new DbgVariable(DV, NULL));
+          addScopeVariable(Scope, new DbgVariable(DV, NULL, this));
       }
     }
     if (ProcessedSPNodes.count(AScope->getScopeNode()) == 0)
@@ -1707,11 +1871,8 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
   if (!MF->getTarget().Options.DisableFramePointerElim(*MF))
     TheCU->addFlag(CurFnDIE, dwarf::DW_AT_APPLE_omit_frame_ptr);
 
-  DebugFrames.push_back(FunctionDebugFrameInfo(Asm->getFunctionNumber(),
-                                               MMI->getFrameMoves()));
-
   // Clear debug info
-  for (DenseMap<LexicalScope *, SmallVector<DbgVariable *, 8> >::iterator
+  for (ScopeVariablesMap::iterator
          I = ScopeVariables.begin(), E = ScopeVariables.end(); I != E; ++I)
     DeleteContainerPointers(I->second);
   ScopeVariables.clear();
@@ -1767,7 +1928,8 @@ void DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, const MDNode *S,
 // Emit Methods
 //===----------------------------------------------------------------------===//
 
-// Compute the size and offset of a DIE.
+// Compute the size and offset of a DIE. The offset is relative to start of the
+// CU. It returns the offset after laying out the DIE.
 unsigned
 DwarfUnits::computeSizeAndOffset(DIE *Die, unsigned Offset) {
   // Get the children.
@@ -1778,7 +1940,7 @@ DwarfUnits::computeSizeAndOffset(DIE *Die, unsigned Offset) {
 
   // Get the abbreviation for this DIE.
   unsigned AbbrevNumber = Die->getAbbrevNumber();
-  const DIEAbbrev *Abbrev = Abbreviations->at(AbbrevNumber - 1);
+  const DIEAbbrev *Abbrev = Abbreviations[AbbrevNumber - 1];
 
   // Set DIE offset
   Die->setOffset(Offset);
@@ -1810,21 +1972,25 @@ DwarfUnits::computeSizeAndOffset(DIE *Die, unsigned Offset) {
   return Offset;
 }
 
-// Compute the size and offset of all the DIEs.
+// Compute the size and offset for each DIE.
 void DwarfUnits::computeSizeAndOffsets() {
-  // Offset from the beginning of debug info section.
-  unsigned AccuOffset = 0;
+  // Offset from the first CU in the debug info section is 0 initially.
+  unsigned SecOffset = 0;
+
+  // Iterate over each compile unit and set the size and offsets for each
+  // DIE within each compile unit. All offsets are CU relative.
   for (SmallVectorImpl<CompileUnit *>::iterator I = CUs.begin(),
          E = CUs.end(); I != E; ++I) {
-    (*I)->setDebugInfoOffset(AccuOffset);
-    unsigned Offset =
-      sizeof(int32_t) + // Length of Compilation Unit Info
-      sizeof(int16_t) + // DWARF version number
-      sizeof(int32_t) + // Offset Into Abbrev. Section
-      sizeof(int8_t);   // Pointer Size (in bytes)
+    (*I)->setDebugInfoOffset(SecOffset);
 
+    // CU-relative offset is reset to 0 here.
+    unsigned Offset = sizeof(int32_t) + // Length of Unit Info
+                      (*I)->getHeaderSize(); // Unit-specific headers
+
+    // EndOffset here is CU-relative, after laying out
+    // all of the CU DIE.
     unsigned EndOffset = computeSizeAndOffset((*I)->getCUDie(), Offset);
-    AccuOffset += EndOffset;
+    SecOffset += EndOffset;
   }
 }
 
@@ -1849,9 +2015,16 @@ void DwarfDebug::emitSectionLabels() {
   DwarfLineSectionSym =
     emitSectionSym(Asm, TLOF.getDwarfLineSection(), "section_line");
   emitSectionSym(Asm, TLOF.getDwarfLocSection());
-  if (GenerateDwarfPubNamesSection)
+  if (GenerateGnuPubSections) {
+    DwarfGnuPubNamesSectionSym =
+        emitSectionSym(Asm, TLOF.getDwarfGnuPubNamesSection());
+    DwarfGnuPubTypesSectionSym =
+        emitSectionSym(Asm, TLOF.getDwarfGnuPubTypesSection());
+  } else if (HasDwarfPubSections) {
     emitSectionSym(Asm, TLOF.getDwarfPubNamesSection());
-  emitSectionSym(Asm, TLOF.getDwarfPubTypesSection());
+    emitSectionSym(Asm, TLOF.getDwarfPubTypesSection());
+  }
+
   DwarfStrSectionSym =
     emitSectionSym(Asm, TLOF.getDwarfStrSection(), "info_string");
   if (useSplitDwarf()) {
@@ -1871,10 +2044,10 @@ void DwarfDebug::emitSectionLabels() {
 }
 
 // Recursively emits a debug information entry.
-void DwarfDebug::emitDIE(DIE *Die, std::vector<DIEAbbrev *> *Abbrevs) {
+void DwarfDebug::emitDIE(DIE *Die, ArrayRef<DIEAbbrev *> Abbrevs) {
   // Get the abbreviation for this DIE.
   unsigned AbbrevNumber = Die->getAbbrevNumber();
-  const DIEAbbrev *Abbrev = Abbrevs->at(AbbrevNumber - 1);
+  const DIEAbbrev *Abbrev = Abbrevs[AbbrevNumber - 1];
 
   // Emit the code (index) for the abbreviation.
   if (Asm->isVerbose())
@@ -1889,26 +2062,44 @@ void DwarfDebug::emitDIE(DIE *Die, std::vector<DIEAbbrev *> *Abbrevs) {
 
   // Emit the DIE attribute values.
   for (unsigned i = 0, N = Values.size(); i < N; ++i) {
-    unsigned Attr = AbbrevData[i].getAttribute();
-    unsigned Form = AbbrevData[i].getForm();
+    dwarf::Attribute Attr = AbbrevData[i].getAttribute();
+    dwarf::Form Form = AbbrevData[i].getForm();
     assert(Form && "Too many attributes for DIE (check abbreviation)");
 
     if (Asm->isVerbose())
       Asm->OutStreamer.AddComment(dwarf::AttributeString(Attr));
 
     switch (Attr) {
-    case dwarf::DW_AT_abstract_origin: {
+    case dwarf::DW_AT_abstract_origin:
+    case dwarf::DW_AT_type:
+    case dwarf::DW_AT_friend:
+    case dwarf::DW_AT_specification:
+    case dwarf::DW_AT_import:
+    case dwarf::DW_AT_containing_type: {
       DIEEntry *E = cast<DIEEntry>(Values[i]);
       DIE *Origin = E->getEntry();
       unsigned Addr = Origin->getOffset();
       if (Form == dwarf::DW_FORM_ref_addr) {
+        assert(!useSplitDwarf() && "TODO: dwo files can't have relocations.");
         // For DW_FORM_ref_addr, output the offset from beginning of debug info
         // section. Origin->getOffset() returns the offset from start of the
         // compile unit.
-        DwarfUnits &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
-        Addr += Holder.getCUOffset(Origin->getCompileUnit());
+        CompileUnit *CU = CUDieMap.lookup(Origin->getCompileUnit());
+        assert(CU && "CUDie should belong to a CU.");
+        Addr += CU->getDebugInfoOffset();
+        if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+          Asm->EmitLabelPlusOffset(DwarfInfoSectionSym, Addr,
+                                   DIEEntry::getRefAddrSize(Asm));
+        else
+          Asm->EmitLabelOffsetDifference(DwarfInfoSectionSym, Addr,
+                                         DwarfInfoSectionSym,
+                                         DIEEntry::getRefAddrSize(Asm));
+      } else {
+        // Make sure Origin belong to the same CU.
+        assert(Die->getCompileUnit() == Origin->getCompileUnit() &&
+               "The referenced DIE should belong to the same CU in ref4");
+        Asm->EmitInt32(Addr);
       }
-      Asm->EmitInt32(Addr);
       break;
     }
     case dwarf::DW_AT_ranges: {
@@ -1930,7 +2121,7 @@ void DwarfDebug::emitDIE(DIE *Die, std::vector<DIEAbbrev *> *Abbrevs) {
     case dwarf::DW_AT_location: {
       if (DIELabel *L = dyn_cast<DIELabel>(Values[i])) {
         if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
-          Asm->EmitLabelReference(L->getValue(), 4);
+          Asm->EmitSectionOffset(L->getValue(), DwarfDebugLocSectionSym);
         else
           Asm->EmitLabelDifference(L->getValue(), DwarfDebugLocSectionSym, 4);
       } else {
@@ -1984,20 +2175,10 @@ void DwarfUnits::emitUnits(DwarfDebug *DD,
                                     TheCU->getUniqueID()));
 
     // Emit size of content not including length itself
-    unsigned ContentSize = Die->getSize() +
-      sizeof(int16_t) + // DWARF version number
-      sizeof(int32_t) + // Offset Into Abbrev. Section
-      sizeof(int8_t);   // Pointer Size (in bytes)
+    Asm->OutStreamer.AddComment("Length of Unit");
+    Asm->EmitInt32(TheCU->getHeaderSize() + Die->getSize());
 
-    Asm->OutStreamer.AddComment("Length of Compilation Unit Info");
-    Asm->EmitInt32(ContentSize);
-    Asm->OutStreamer.AddComment("DWARF version number");
-    Asm->EmitInt16(dwarf::DWARF_VERSION);
-    Asm->OutStreamer.AddComment("Offset Into Abbrev. Section");
-    Asm->EmitSectionOffset(Asm->GetTempSymbol(ASection->getLabelBeginName()),
-                           ASectionSym);
-    Asm->OutStreamer.AddComment("Address Size (in bytes)");
-    Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
+    TheCU->emitHeader(ASection, ASectionSym);
 
     DD->emitDIE(Die, Abbreviations);
     Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol(USection->getLabelEndName(),
@@ -2005,19 +2186,6 @@ void DwarfUnits::emitUnits(DwarfDebug *DD,
   }
 }
 
-/// For a given compile unit DIE, returns offset from beginning of debug info.
-unsigned DwarfUnits::getCUOffset(DIE *Die) {
-  assert(Die->getTag() == dwarf::DW_TAG_compile_unit  &&
-         "Input DIE should be compile unit in getCUOffset.");
-  for (SmallVectorImpl<CompileUnit *>::iterator I = CUs.begin(),
-       E = CUs.end(); I != E; ++I) {
-    CompileUnit *TheCU = *I;
-    if (TheCU->getCUDie() == Die)
-      return TheCU->getDebugInfoOffset();
-  }
-  llvm_unreachable("The compile unit DIE should belong to CUs in DwarfUnits.");
-}
-
 // Emit the debug info section.
 void DwarfDebug::emitDebugInfo() {
   DwarfUnits &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
@@ -2091,7 +2259,7 @@ void DwarfDebug::emitEndOfLineMatrix(unsigned SectionEnd) {
 
 // Emit visible names into a hashed accelerator table section.
 void DwarfDebug::emitAccelNames() {
-  DwarfAccelTable AT(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
+  DwarfAccelTable AT(DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset,
                                            dwarf::DW_FORM_data4));
   for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
          E = CUMap.end(); I != E; ++I) {
@@ -2099,7 +2267,7 @@ void DwarfDebug::emitAccelNames() {
     const StringMap<std::vector<DIE*> > &Names = TheCU->getAccelNames();
     for (StringMap<std::vector<DIE*> >::const_iterator
            GI = Names.begin(), GE = Names.end(); GI != GE; ++GI) {
-      const char *Name = GI->getKeyData();
+      StringRef Name = GI->getKey();
       const std::vector<DIE *> &Entities = GI->second;
       for (std::vector<DIE *>::const_iterator DI = Entities.begin(),
              DE = Entities.end(); DI != DE; ++DI)
@@ -2120,7 +2288,7 @@ void DwarfDebug::emitAccelNames() {
 // Emit objective C classes and categories into a hashed accelerator table
 // section.
 void DwarfDebug::emitAccelObjC() {
-  DwarfAccelTable AT(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
+  DwarfAccelTable AT(DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset,
                                            dwarf::DW_FORM_data4));
   for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
          E = CUMap.end(); I != E; ++I) {
@@ -2128,7 +2296,7 @@ void DwarfDebug::emitAccelObjC() {
     const StringMap<std::vector<DIE*> > &Names = TheCU->getAccelObjC();
     for (StringMap<std::vector<DIE*> >::const_iterator
            GI = Names.begin(), GE = Names.end(); GI != GE; ++GI) {
-      const char *Name = GI->getKeyData();
+      StringRef Name = GI->getKey();
       const std::vector<DIE *> &Entities = GI->second;
       for (std::vector<DIE *>::const_iterator DI = Entities.begin(),
              DE = Entities.end(); DI != DE; ++DI)
@@ -2148,7 +2316,7 @@ void DwarfDebug::emitAccelObjC() {
 
 // Emit namespace dies into a hashed accelerator table.
 void DwarfDebug::emitAccelNamespaces() {
-  DwarfAccelTable AT(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
+  DwarfAccelTable AT(DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset,
                                            dwarf::DW_FORM_data4));
   for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
          E = CUMap.end(); I != E; ++I) {
@@ -2156,7 +2324,7 @@ void DwarfDebug::emitAccelNamespaces() {
     const StringMap<std::vector<DIE*> > &Names = TheCU->getAccelNamespace();
     for (StringMap<std::vector<DIE*> >::const_iterator
            GI = Names.begin(), GE = Names.end(); GI != GE; ++GI) {
-      const char *Name = GI->getKeyData();
+      StringRef Name = GI->getKey();
       const std::vector<DIE *> &Entities = GI->second;
       for (std::vector<DIE *>::const_iterator DI = Entities.begin(),
              DE = Entities.end(); DI != DE; ++DI)
@@ -2177,11 +2345,11 @@ void DwarfDebug::emitAccelNamespaces() {
 // Emit type dies into a hashed accelerator table.
 void DwarfDebug::emitAccelTypes() {
   std::vector<DwarfAccelTable::Atom> Atoms;
-  Atoms.push_back(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
+  Atoms.push_back(DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset,
                                         dwarf::DW_FORM_data4));
-  Atoms.push_back(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeTag,
+  Atoms.push_back(DwarfAccelTable::Atom(dwarf::DW_ATOM_die_tag,
                                         dwarf::DW_FORM_data2));
-  Atoms.push_back(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeTypeFlags,
+  Atoms.push_back(DwarfAccelTable::Atom(dwarf::DW_ATOM_type_flags,
                                         dwarf::DW_FORM_data1));
   DwarfAccelTable AT(Atoms);
   for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
@@ -2191,7 +2359,7 @@ void DwarfDebug::emitAccelTypes() {
       = TheCU->getAccelTypes();
     for (StringMap<std::vector<std::pair<DIE*, unsigned> > >::const_iterator
            GI = Names.begin(), GE = Names.end(); GI != GE; ++GI) {
-      const char *Name = GI->getKeyData();
+      StringRef Name = GI->getKey();
       const std::vector<std::pair<DIE *, unsigned> > &Entities = GI->second;
       for (std::vector<std::pair<DIE *, unsigned> >::const_iterator DI
              = Entities.begin(), DE = Entities.end(); DI !=DE; ++DI)
@@ -2209,23 +2377,85 @@ void DwarfDebug::emitAccelTypes() {
   AT.Emit(Asm, SectionBegin, &InfoHolder);
 }
 
-/// emitDebugPubnames - Emit visible names into a debug pubnames section.
+// Public name handling.
+// The format for the various pubnames:
+//
+// dwarf pubnames - offset/name pairs where the offset is the offset into the CU
+// for the DIE that is named.
+//
+// gnu pubnames - offset/index value/name tuples where the offset is the offset
+// into the CU and the index value is computed according to the type of value
+// for the DIE that is named.
+//
+// For type units the offset is the offset of the skeleton DIE. For split dwarf
+// it's the offset within the debug_info/debug_types dwo section, however, the
+// reference in the pubname header doesn't change.
+
+/// computeIndexValue - Compute the gdb index value for the DIE and CU.
+static dwarf::PubIndexEntryDescriptor computeIndexValue(CompileUnit *CU,
+                                                        DIE *Die) {
+  dwarf::GDBIndexEntryLinkage Linkage = dwarf::GIEL_STATIC;
+
+  // We could have a specification DIE that has our most of our knowledge,
+  // look for that now.
+  DIEValue *SpecVal = Die->findAttribute(dwarf::DW_AT_specification);
+  if (SpecVal) {
+    DIE *SpecDIE = cast<DIEEntry>(SpecVal)->getEntry();
+    if (SpecDIE->findAttribute(dwarf::DW_AT_external))
+      Linkage = dwarf::GIEL_EXTERNAL;
+  } else if (Die->findAttribute(dwarf::DW_AT_external))
+    Linkage = dwarf::GIEL_EXTERNAL;
+
+  switch (Die->getTag()) {
+  case dwarf::DW_TAG_class_type:
+  case dwarf::DW_TAG_structure_type:
+  case dwarf::DW_TAG_union_type:
+  case dwarf::DW_TAG_enumeration_type:
+    return dwarf::PubIndexEntryDescriptor(
+        dwarf::GIEK_TYPE, CU->getLanguage() != dwarf::DW_LANG_C_plus_plus
+                              ? dwarf::GIEL_STATIC
+                              : dwarf::GIEL_EXTERNAL);
+  case dwarf::DW_TAG_typedef:
+  case dwarf::DW_TAG_base_type:
+  case dwarf::DW_TAG_subrange_type:
+    return dwarf::PubIndexEntryDescriptor(dwarf::GIEK_TYPE, dwarf::GIEL_STATIC);
+  case dwarf::DW_TAG_namespace:
+    return dwarf::GIEK_TYPE;
+  case dwarf::DW_TAG_subprogram:
+    return dwarf::PubIndexEntryDescriptor(dwarf::GIEK_FUNCTION, Linkage);
+  case dwarf::DW_TAG_constant:
+  case dwarf::DW_TAG_variable:
+    return dwarf::PubIndexEntryDescriptor(dwarf::GIEK_VARIABLE, Linkage);
+  case dwarf::DW_TAG_enumerator:
+    return dwarf::PubIndexEntryDescriptor(dwarf::GIEK_VARIABLE,
+                                          dwarf::GIEL_STATIC);
+  default:
+    return dwarf::GIEK_NONE;
+  }
+}
+
+/// emitDebugPubNames - Emit visible names into a debug pubnames section.
 ///
-void DwarfDebug::emitDebugPubnames() {
+void DwarfDebug::emitDebugPubNames(bool GnuStyle) {
   const MCSection *ISec = Asm->getObjFileLowering().getDwarfInfoSection();
+  const MCSection *PSec =
+      GnuStyle ? Asm->getObjFileLowering().getDwarfGnuPubNamesSection()
+               : Asm->getObjFileLowering().getDwarfPubNamesSection();
 
   typedef DenseMap<const MDNode*, CompileUnit*> CUMapType;
   for (CUMapType::iterator I = CUMap.begin(), E = CUMap.end(); I != E; ++I) {
     CompileUnit *TheCU = I->second;
     unsigned ID = TheCU->getUniqueID();
 
-    if (TheCU->getGlobalNames().empty())
-      continue;
-
     // Start the dwarf pubnames section.
-    Asm->OutStreamer.SwitchSection(
-      Asm->getObjFileLowering().getDwarfPubNamesSection());
+    Asm->OutStreamer.SwitchSection(PSec);
+
+    // Emit a label so we can reference the beginning of this pubname section.
+    if (GnuStyle)
+      Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("gnu_pubnames",
+                                                    TheCU->getUniqueID()));
 
+    // Emit the header.
     Asm->OutStreamer.AddComment("Length of Public Names Info");
     Asm->EmitLabelDifference(Asm->GetTempSymbol("pubnames_end", ID),
                              Asm->GetTempSymbol("pubnames_begin", ID), 4);
@@ -2233,7 +2463,7 @@ void DwarfDebug::emitDebugPubnames() {
     Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("pubnames_begin", ID));
 
     Asm->OutStreamer.AddComment("DWARF Version");
-    Asm->EmitInt16(dwarf::DWARF_VERSION);
+    Asm->EmitInt16(dwarf::DW_PUBNAMES_VERSION);
 
     Asm->OutStreamer.AddComment("Offset of Compilation Unit Info");
     Asm->EmitSectionOffset(Asm->GetTempSymbol(ISec->getLabelBeginName(), ID),
@@ -2244,18 +2474,27 @@ void DwarfDebug::emitDebugPubnames() {
                              Asm->GetTempSymbol(ISec->getLabelBeginName(), ID),
                              4);
 
+    // Emit the pubnames for this compilation unit.
     const StringMap<DIE*> &Globals = TheCU->getGlobalNames();
     for (StringMap<DIE*>::const_iterator
            GI = Globals.begin(), GE = Globals.end(); GI != GE; ++GI) {
       const char *Name = GI->getKeyData();
-      const DIE *Entity = GI->second;
+      DIE *Entity = GI->second;
 
       Asm->OutStreamer.AddComment("DIE offset");
       Asm->EmitInt32(Entity->getOffset());
 
+      if (GnuStyle) {
+        dwarf::PubIndexEntryDescriptor Desc = computeIndexValue(TheCU, Entity);
+        Asm->OutStreamer.AddComment(
+            Twine("Kind: ") + dwarf::GDBIndexEntryKindString(Desc.Kind) + ", " +
+            dwarf::GDBIndexEntryLinkageString(Desc.Linkage));
+        Asm->EmitInt8(Desc.toBits());
+      }
+
       if (Asm->isVerbose())
         Asm->OutStreamer.AddComment("External Name");
-      Asm->OutStreamer.EmitBytes(StringRef(Name, strlen(Name)+1), 0);
+      Asm->OutStreamer.EmitBytes(StringRef(Name, GI->getKeyLength()+1));
     }
 
     Asm->OutStreamer.AddComment("End Mark");
@@ -2264,55 +2503,78 @@ void DwarfDebug::emitDebugPubnames() {
   }
 }
 
-void DwarfDebug::emitDebugPubTypes() {
+void DwarfDebug::emitDebugPubTypes(bool GnuStyle) {
+  const MCSection *ISec = Asm->getObjFileLowering().getDwarfInfoSection();
+  const MCSection *PSec =
+      GnuStyle ? Asm->getObjFileLowering().getDwarfGnuPubTypesSection()
+               : Asm->getObjFileLowering().getDwarfPubTypesSection();
+
   for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
-         E = CUMap.end(); I != E; ++I) {
+                                                         E = CUMap.end();
+       I != E; ++I) {
     CompileUnit *TheCU = I->second;
     // Start the dwarf pubtypes section.
-    Asm->OutStreamer.SwitchSection(
-      Asm->getObjFileLowering().getDwarfPubTypesSection());
+    Asm->OutStreamer.SwitchSection(PSec);
+
+    // Emit a label so we can reference the beginning of this pubtype section.
+    if (GnuStyle)
+      Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("gnu_pubtypes",
+                                                    TheCU->getUniqueID()));
+
+    // Emit the header.
     Asm->OutStreamer.AddComment("Length of Public Types Info");
     Asm->EmitLabelDifference(
-      Asm->GetTempSymbol("pubtypes_end", TheCU->getUniqueID()),
-      Asm->GetTempSymbol("pubtypes_begin", TheCU->getUniqueID()), 4);
+        Asm->GetTempSymbol("pubtypes_end", TheCU->getUniqueID()),
+        Asm->GetTempSymbol("pubtypes_begin", TheCU->getUniqueID()), 4);
 
-    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("pubtypes_begin",
-                                                  TheCU->getUniqueID()));
+    Asm->OutStreamer.EmitLabel(
+        Asm->GetTempSymbol("pubtypes_begin", TheCU->getUniqueID()));
 
-    if (Asm->isVerbose()) Asm->OutStreamer.AddComment("DWARF Version");
-    Asm->EmitInt16(dwarf::DWARF_VERSION);
+    if (Asm->isVerbose())
+      Asm->OutStreamer.AddComment("DWARF Version");
+    Asm->EmitInt16(dwarf::DW_PUBTYPES_VERSION);
 
     Asm->OutStreamer.AddComment("Offset of Compilation Unit Info");
-    const MCSection *ISec = Asm->getObjFileLowering().getDwarfInfoSection();
-    Asm->EmitSectionOffset(Asm->GetTempSymbol(ISec->getLabelBeginName(),
-                                              TheCU->getUniqueID()),
-                           DwarfInfoSectionSym);
+    Asm->EmitSectionOffset(
+        Asm->GetTempSymbol(ISec->getLabelBeginName(), TheCU->getUniqueID()),
+        DwarfInfoSectionSym);
 
     Asm->OutStreamer.AddComment("Compilation Unit Length");
-    Asm->EmitLabelDifference(Asm->GetTempSymbol(ISec->getLabelEndName(),
-                                                TheCU->getUniqueID()),
-                             Asm->GetTempSymbol(ISec->getLabelBeginName(),
-                                                TheCU->getUniqueID()),
-                             4);
-
-    const StringMap<DIE*> &Globals = TheCU->getGlobalTypes();
-    for (StringMap<DIE*>::const_iterator
-           GI = Globals.begin(), GE = Globals.end(); GI != GE; ++GI) {
+    Asm->EmitLabelDifference(
+        Asm->GetTempSymbol(ISec->getLabelEndName(), TheCU->getUniqueID()),
+        Asm->GetTempSymbol(ISec->getLabelBeginName(), TheCU->getUniqueID()), 4);
+
+    // Emit the pubtypes.
+    const StringMap<DIE *> &Globals = TheCU->getGlobalTypes();
+    for (StringMap<DIE *>::const_iterator GI = Globals.begin(),
+                                          GE = Globals.end();
+         GI != GE; ++GI) {
       const char *Name = GI->getKeyData();
       DIE *Entity = GI->second;
 
-      if (Asm->isVerbose()) Asm->OutStreamer.AddComment("DIE offset");
+      if (Asm->isVerbose())
+        Asm->OutStreamer.AddComment("DIE offset");
       Asm->EmitInt32(Entity->getOffset());
 
-      if (Asm->isVerbose()) Asm->OutStreamer.AddComment("External Name");
+      if (GnuStyle) {
+        dwarf::PubIndexEntryDescriptor Desc = computeIndexValue(TheCU, Entity);
+        Asm->OutStreamer.AddComment(
+            Twine("Kind: ") + dwarf::GDBIndexEntryKindString(Desc.Kind) + ", " +
+            dwarf::GDBIndexEntryLinkageString(Desc.Linkage));
+        Asm->EmitInt8(Desc.toBits());
+      }
+
+      if (Asm->isVerbose())
+        Asm->OutStreamer.AddComment("External Name");
+
       // Emit the name with a terminating null byte.
-      Asm->OutStreamer.EmitBytes(StringRef(Name, GI->getKeyLength()+1));
+      Asm->OutStreamer.EmitBytes(StringRef(Name, GI->getKeyLength() + 1));
     }
 
     Asm->OutStreamer.AddComment("End Mark");
     Asm->EmitInt32(0);
-    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("pubtypes_end",
-                                                  TheCU->getUniqueID()));
+    Asm->OutStreamer.EmitLabel(
+        Asm->GetTempSymbol("pubtypes_end", TheCU->getUniqueID()));
   }
 }
 
@@ -2367,24 +2629,18 @@ void DwarfUnits::emitAddresses(const MCSection *AddrSection) {
   // Start the dwarf addr section.
   Asm->OutStreamer.SwitchSection(AddrSection);
 
-  // Get all of the string pool entries and put them in an array by their ID so
-  // we can sort them.
-  SmallVector<std::pair<unsigned,
-                        std::pair<MCSymbol*, unsigned>* >, 64> Entries;
+  // Order the address pool entries by ID
+  SmallVector<const MCExpr *, 64> Entries(AddressPool.size());
 
-  for (DenseMap<MCSymbol*, std::pair<MCSymbol*, unsigned> >::iterator
-         I = AddressPool.begin(), E = AddressPool.end();
+  for (DenseMap<const MCExpr *, unsigned>::iterator I = AddressPool.begin(),
+                                                    E = AddressPool.end();
        I != E; ++I)
-    Entries.push_back(std::make_pair(I->second.second, &(I->second)));
-
-  array_pod_sort(Entries.begin(), Entries.end());
+    Entries[I->second] = I->first;
 
   for (unsigned i = 0, e = Entries.size(); i != e; ++i) {
-    // Emit a label for reference from debug information entries.
-    MCSymbol *Sym = Entries[i].second->first;
-    if (Sym)
-      Asm->EmitLabelReference(Entries[i].second->first,
-                              Asm->getDataLayout().getPointerSize());
+    // Emit an expression for reference from debug information entries.
+    if (const MCExpr *Expr = Entries[i])
+      Asm->OutStreamer.EmitValue(Expr, Asm->getDataLayout().getPointerSize());
     else
       Asm->OutStreamer.EmitIntValue(0, Asm->getDataLayout().getPointerSize());
   }
@@ -2397,7 +2653,7 @@ void DwarfDebug::emitDebugStr() {
   Holder.emitStrings(Asm->getObjFileLowering().getDwarfStrSection());
 }
 
-// Emit visible names into a debug loc section.
+// Emit locations into the debug loc section.
 void DwarfDebug::emitDebugLoc() {
   if (DotDebugLocEntries.empty())
     return;
@@ -2426,9 +2682,9 @@ void DwarfDebug::emitDebugLoc() {
       Asm->OutStreamer.EmitIntValue(0, Size);
       Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("debug_loc", index));
     } else {
-      Asm->OutStreamer.EmitSymbolValue(Entry.Begin, Size);
-      Asm->OutStreamer.EmitSymbolValue(Entry.End, Size);
-      DIVariable DV(Entry.Variable);
+      Asm->OutStreamer.EmitSymbolValue(Entry.getBeginSym(), Size);
+      Asm->OutStreamer.EmitSymbolValue(Entry.getEndSym(), Size);
+      DIVariable DV(Entry.getVariable());
       Asm->OutStreamer.AddComment("Loc expr size");
       MCSymbol *begin = Asm->OutStreamer.getContext().CreateTempSymbol();
       MCSymbol *end = Asm->OutStreamer.getContext().CreateTempSymbol();
@@ -2448,17 +2704,18 @@ void DwarfDebug::emitDebugLoc() {
           Asm->EmitULEB128(Entry.getInt());
         }
       } else if (Entry.isLocation()) {
+        MachineLocation Loc = Entry.getLoc();
         if (!DV.hasComplexAddress())
           // Regular entry.
-          Asm->EmitDwarfRegOp(Entry.Loc);
+          Asm->EmitDwarfRegOp(Loc, DV.isIndirect());
         else {
           // Complex address entry.
           unsigned N = DV.getNumAddrElements();
           unsigned i = 0;
           if (N >= 2 && DV.getAddrElement(0) == DIBuilder::OpPlus) {
-            if (Entry.Loc.getOffset()) {
+            if (Loc.getOffset()) {
               i = 2;
-              Asm->EmitDwarfRegOp(Entry.Loc);
+              Asm->EmitDwarfRegOp(Loc, DV.isIndirect());
               Asm->OutStreamer.AddComment("DW_OP_deref");
               Asm->EmitInt8(dwarf::DW_OP_deref);
               Asm->OutStreamer.AddComment("DW_OP_plus_uconst");
@@ -2467,12 +2724,12 @@ void DwarfDebug::emitDebugLoc() {
             } else {
               // If first address element is OpPlus then emit
               // DW_OP_breg + Offset instead of DW_OP_reg + Offset.
-              MachineLocation Loc(Entry.Loc.getReg(), DV.getAddrElement(1));
-              Asm->EmitDwarfRegOp(Loc);
+              MachineLocation TLoc(Loc.getReg(), DV.getAddrElement(1));
+              Asm->EmitDwarfRegOp(TLoc, DV.isIndirect());
               i = 2;
             }
           } else {
-            Asm->EmitDwarfRegOp(Entry.Loc);
+            Asm->EmitDwarfRegOp(Loc, DV.isIndirect());
           }
 
           // Emit remaining complex address elements.
@@ -2482,7 +2739,7 @@ void DwarfDebug::emitDebugLoc() {
               Asm->EmitInt8(dwarf::DW_OP_plus_uconst);
               Asm->EmitULEB128(DV.getAddrElement(++i));
             } else if (Element == DIBuilder::OpDeref) {
-              if (!Entry.Loc.isReg())
+              if (!Loc.isReg())
                 Asm->EmitInt8(dwarf::DW_OP_deref);
             } else
               llvm_unreachable("unknown Opcode found in complex address");
@@ -2496,18 +2753,178 @@ void DwarfDebug::emitDebugLoc() {
   }
 }
 
-// Emit visible names into a debug aranges section.
+struct SymbolCUSorter {
+  SymbolCUSorter(const MCStreamer &s) : Streamer(s) {}
+  const MCStreamer &Streamer;
+
+  bool operator() (const SymbolCU &A, const SymbolCU &B) {
+    unsigned IA = A.Sym ? Streamer.GetSymbolOrder(A.Sym) : 0;
+    unsigned IB = B.Sym ? Streamer.GetSymbolOrder(B.Sym) : 0;
+
+    // Symbols with no order assigned should be placed at the end.
+    // (e.g. section end labels)
+    if (IA == 0)
+      IA = (unsigned)(-1);
+    if (IB == 0)
+      IB = (unsigned)(-1);
+    return IA < IB;
+  }
+};
+
+static bool CUSort(const CompileUnit *A, const CompileUnit *B) {
+    return (A->getUniqueID() < B->getUniqueID());
+}
+
+struct ArangeSpan {
+  const MCSymbol *Start, *End;
+};
+
+// Emit a debug aranges section, containing a CU lookup for any
+// address we can tie back to a CU.
 void DwarfDebug::emitDebugARanges() {
   // Start the dwarf aranges section.
-  Asm->OutStreamer.SwitchSection(
-                          Asm->getObjFileLowering().getDwarfARangesSection());
+  Asm->OutStreamer
+      .SwitchSection(Asm->getObjFileLowering().getDwarfARangesSection());
+
+  typedef DenseMap<CompileUnit *, std::vector<ArangeSpan> > SpansType;
+
+  SpansType Spans;
+
+  // Build a list of sections used.
+  std::vector<const MCSection *> Sections;
+  for (SectionMapType::iterator it = SectionMap.begin(); it != SectionMap.end();
+       it++) {
+    const MCSection *Section = it->first;
+    Sections.push_back(Section);
+  }
+
+  // Sort the sections into order.
+  // This is only done to ensure consistent output order across different runs.
+  std::sort(Sections.begin(), Sections.end(), SectionSort);
+
+  // Build a set of address spans, sorted by CU.
+  for (size_t SecIdx=0;SecIdx<Sections.size();SecIdx++) {
+    const MCSection *Section = Sections[SecIdx];
+    SmallVector<SymbolCU, 8> &List = SectionMap[Section];
+    if (List.size() < 2)
+      continue;
+
+    // Sort the symbols by offset within the section.
+    SymbolCUSorter sorter(Asm->OutStreamer);
+    std::sort(List.begin(), List.end(), sorter);
+
+    // If we have no section (e.g. common), just write out
+    // individual spans for each symbol.
+    if (Section == NULL) {
+      for (size_t n = 0; n < List.size(); n++) {
+        const SymbolCU &Cur = List[n];
+
+        ArangeSpan Span;
+        Span.Start = Cur.Sym;
+        Span.End = NULL;
+        if (Cur.CU)
+          Spans[Cur.CU].push_back(Span);
+      }
+    } else {
+      // Build spans between each label.
+      const MCSymbol *StartSym = List[0].Sym;
+      for (size_t n = 1; n < List.size(); n++) {
+        const SymbolCU &Prev = List[n - 1];
+        const SymbolCU &Cur = List[n];
+
+        // Try and build the longest span we can within the same CU.
+        if (Cur.CU != Prev.CU) {
+          ArangeSpan Span;
+          Span.Start = StartSym;
+          Span.End = Cur.Sym;
+          Spans[Prev.CU].push_back(Span);
+          StartSym = Cur.Sym;
+        }
+      }
+    }
+  }
+
+  const MCSection *ISec = Asm->getObjFileLowering().getDwarfInfoSection();
+  unsigned PtrSize = Asm->getDataLayout().getPointerSize();
+
+  // Build a list of CUs used.
+  std::vector<CompileUnit *> CUs;
+  for (SpansType::iterator it = Spans.begin(); it != Spans.end(); it++) {
+    CompileUnit *CU = it->first;
+    CUs.push_back(CU);
+  }
+
+  // Sort the CU list (again, to ensure consistent output order).
+  std::sort(CUs.begin(), CUs.end(), CUSort);
+
+  // Emit an arange table for each CU we used.
+  for (size_t CUIdx=0;CUIdx<CUs.size();CUIdx++) {
+    CompileUnit *CU = CUs[CUIdx];
+    std::vector<ArangeSpan> &List = Spans[CU];
+
+    // Emit size of content not including length itself.
+    unsigned ContentSize
+        = sizeof(int16_t) // DWARF ARange version number
+        + sizeof(int32_t) // Offset of CU in the .debug_info section
+        + sizeof(int8_t)  // Pointer Size (in bytes)
+        + sizeof(int8_t); // Segment Size (in bytes)
+
+    unsigned TupleSize = PtrSize * 2;
+
+    // 7.20 in the Dwarf specs requires the table to be aligned to a tuple.
+    unsigned Padding = 0;
+    while (((sizeof(int32_t) + ContentSize + Padding) % TupleSize) != 0)
+      Padding++;
+
+    ContentSize += Padding;
+    ContentSize += (List.size() + 1) * TupleSize;
+
+    // For each compile unit, write the list of spans it covers.
+    Asm->OutStreamer.AddComment("Length of ARange Set");
+    Asm->EmitInt32(ContentSize);
+    Asm->OutStreamer.AddComment("DWARF Arange version number");
+    Asm->EmitInt16(dwarf::DW_ARANGES_VERSION);
+    Asm->OutStreamer.AddComment("Offset Into Debug Info Section");
+    Asm->EmitSectionOffset(
+        Asm->GetTempSymbol(ISec->getLabelBeginName(), CU->getUniqueID()),
+        DwarfInfoSectionSym);
+    Asm->OutStreamer.AddComment("Address Size (in bytes)");
+    Asm->EmitInt8(PtrSize);
+    Asm->OutStreamer.AddComment("Segment Size (in bytes)");
+    Asm->EmitInt8(0);
+
+    for (unsigned n = 0; n < Padding; n++)
+      Asm->EmitInt8(0xff);
+
+    for (unsigned n = 0; n < List.size(); n++) {
+      const ArangeSpan &Span = List[n];
+      Asm->EmitLabelReference(Span.Start, PtrSize);
+
+      // Calculate the size as being from the span start to it's end.
+      if (Span.End) {
+        Asm->EmitLabelDifference(Span.End, Span.Start, PtrSize);
+      } else {
+        // For symbols without an end marker (e.g. common), we
+        // write a single arange entry containing just that one symbol.
+        uint64_t Size = SymSize[Span.Start];
+        if (Size == 0)
+          Size = 1;
+
+        Asm->OutStreamer.EmitIntValue(Size, PtrSize);
+      }
+    }
+
+    Asm->OutStreamer.AddComment("ARange terminator");
+    Asm->OutStreamer.EmitIntValue(0, PtrSize);
+    Asm->OutStreamer.EmitIntValue(0, PtrSize);
+  }
 }
 
 // Emit visible names into a debug ranges section.
 void DwarfDebug::emitDebugRanges() {
   // Start the dwarf ranges section.
-  Asm->OutStreamer.SwitchSection(
-    Asm->getObjFileLowering().getDwarfRangesSection());
+  Asm->OutStreamer
+      .SwitchSection(Asm->getObjFileLowering().getDwarfRangesSection());
   unsigned char Size = Asm->getDataLayout().getPointerSize();
   for (SmallVectorImpl<const MCSymbol *>::iterator
          I = DebugRangeSymbols.begin(), E = DebugRangeSymbols.end();
@@ -2528,113 +2945,27 @@ void DwarfDebug::emitDebugMacInfo() {
   }
 }
 
-// Emit inline info using following format.
-// Section Header:
-// 1. length of section
-// 2. Dwarf version number
-// 3. address size.
-//
-// Entries (one "entry" for each function that was inlined):
-//
-// 1. offset into __debug_str section for MIPS linkage name, if exists;
-//   otherwise offset into __debug_str for regular function name.
-// 2. offset into __debug_str section for regular function name.
-// 3. an unsigned LEB128 number indicating the number of distinct inlining
-// instances for the function.
-//
-// The rest of the entry consists of a {die_offset, low_pc} pair for each
-// inlined instance; the die_offset points to the inlined_subroutine die in the
-// __debug_info section, and the low_pc is the starting address for the
-// inlining instance.
-void DwarfDebug::emitDebugInlineInfo() {
-  if (!Asm->MAI->doesDwarfUseInlineInfoSection())
-    return;
-
-  if (!FirstCU)
-    return;
-
-  Asm->OutStreamer.SwitchSection(
-                        Asm->getObjFileLowering().getDwarfDebugInlineSection());
-
-  Asm->OutStreamer.AddComment("Length of Debug Inlined Information Entry");
-  Asm->EmitLabelDifference(Asm->GetTempSymbol("debug_inlined_end", 1),
-                           Asm->GetTempSymbol("debug_inlined_begin", 1), 4);
-
-  Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("debug_inlined_begin", 1));
-
-  Asm->OutStreamer.AddComment("Dwarf Version");
-  Asm->EmitInt16(dwarf::DWARF_VERSION);
-  Asm->OutStreamer.AddComment("Address Size (in bytes)");
-  Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
-
-  for (SmallVectorImpl<const MDNode *>::iterator I = InlinedSPNodes.begin(),
-         E = InlinedSPNodes.end(); I != E; ++I) {
-
-    const MDNode *Node = *I;
-    DenseMap<const MDNode *, SmallVector<InlineInfoLabels, 4> >::iterator II
-      = InlineInfo.find(Node);
-    SmallVectorImpl<InlineInfoLabels> &Labels = II->second;
-    DISubprogram SP(Node);
-    StringRef LName = SP.getLinkageName();
-    StringRef Name = SP.getName();
-
-    Asm->OutStreamer.AddComment("MIPS linkage name");
-    if (LName.empty())
-      Asm->EmitSectionOffset(InfoHolder.getStringPoolEntry(Name),
-                             DwarfStrSectionSym);
-    else
-      Asm->EmitSectionOffset(InfoHolder
-                             .getStringPoolEntry(getRealLinkageName(LName)),
-                             DwarfStrSectionSym);
-
-    Asm->OutStreamer.AddComment("Function name");
-    Asm->EmitSectionOffset(InfoHolder.getStringPoolEntry(Name),
-                           DwarfStrSectionSym);
-    Asm->EmitULEB128(Labels.size(), "Inline count");
-
-    for (SmallVectorImpl<InlineInfoLabels>::iterator LI = Labels.begin(),
-           LE = Labels.end(); LI != LE; ++LI) {
-      if (Asm->isVerbose()) Asm->OutStreamer.AddComment("DIE offset");
-      Asm->EmitInt32(LI->second->getOffset());
-
-      if (Asm->isVerbose()) Asm->OutStreamer.AddComment("low_pc");
-      Asm->OutStreamer.EmitSymbolValue(LI->first,
-                                       Asm->getDataLayout().getPointerSize());
-    }
-  }
-
-  Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("debug_inlined_end", 1));
-}
-
 // DWARF5 Experimental Separate Dwarf emitters.
 
 // This DIE has the following attributes: DW_AT_comp_dir, DW_AT_stmt_list,
 // DW_AT_low_pc, DW_AT_high_pc, DW_AT_ranges, DW_AT_dwo_name, DW_AT_dwo_id,
-// DW_AT_ranges_base, DW_AT_addr_base. If DW_AT_ranges is present,
-// DW_AT_low_pc and DW_AT_high_pc are not used, and vice versa.
-CompileUnit *DwarfDebug::constructSkeletonCU(const MDNode *N) {
-  DICompileUnit DIUnit(N);
-  CompilationDir = DIUnit.getDirectory();
+// DW_AT_ranges_base, DW_AT_addr_base.
+CompileUnit *DwarfDebug::constructSkeletonCU(const CompileUnit *CU) {
 
   DIE *Die = new DIE(dwarf::DW_TAG_compile_unit);
-  CompileUnit *NewCU = new CompileUnit(GlobalCUIndexCount++,
-                                       DIUnit.getLanguage(), Die, Asm,
-                                       this, &SkeletonHolder);
+  CompileUnit *NewCU = new CompileUnit(CU->getUniqueID(), Die, CU->getNode(),
+                                       Asm, this, &SkeletonHolder);
 
   NewCU->addLocalString(Die, dwarf::DW_AT_GNU_dwo_name,
-                        DIUnit.getSplitDebugFilename());
-
-  // This should be a unique identifier when we want to build .dwp files.
-  NewCU->addUInt(Die, dwarf::DW_AT_GNU_dwo_id, dwarf::DW_FORM_data8, 0);
+                        CU->getNode().getSplitDebugFilename());
 
   // Relocate to the beginning of the addr_base section, else 0 for the
   // beginning of the one for this compile unit.
   if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
-    NewCU->addLabel(Die, dwarf::DW_AT_GNU_addr_base, dwarf::DW_FORM_sec_offset,
-                    DwarfAddrSectionSym);
+    NewCU->addSectionLabel(Die, dwarf::DW_AT_GNU_addr_base,
+                           DwarfAddrSectionSym);
   else
-    NewCU->addUInt(Die, dwarf::DW_AT_GNU_addr_base,
-                   dwarf::DW_FORM_sec_offset, 0);
+    NewCU->addSectionOffset(Die, dwarf::DW_AT_GNU_addr_base, 0);
 
   // 2.17.1 requires that we use DW_AT_low_pc for a single entry point
   // into an entity. We're using 0, or a NULL label for this.
@@ -2644,14 +2975,47 @@ CompileUnit *DwarfDebug::constructSkeletonCU(const MDNode *N) {
   // compile unit in debug_line section.
   // FIXME: Should handle multiple compile units.
   if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
-    NewCU->addLabel(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_sec_offset,
-                    DwarfLineSectionSym);
+    NewCU->addSectionLabel(Die, dwarf::DW_AT_stmt_list,
+                           DwarfLineSectionSym);
   else
-    NewCU->addUInt(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_sec_offset, 0);
+    NewCU->addSectionOffset(Die, dwarf::DW_AT_stmt_list, 0);
 
   if (!CompilationDir.empty())
     NewCU->addLocalString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
 
+  // Flags to let the linker know we have emitted new style pubnames.
+  if (GenerateGnuPubSections) {
+    if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+      NewCU->addSectionLabel(
+          Die, dwarf::DW_AT_GNU_pubnames,
+          Asm->GetTempSymbol("gnu_pubnames", NewCU->getUniqueID()));
+    else
+      NewCU->addSectionDelta(
+          Die, dwarf::DW_AT_GNU_pubnames,
+          Asm->GetTempSymbol("gnu_pubnames", NewCU->getUniqueID()),
+          DwarfGnuPubNamesSectionSym);
+
+    if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+      NewCU->addSectionLabel(
+          Die, dwarf::DW_AT_GNU_pubtypes,
+          Asm->GetTempSymbol("gnu_pubtypes", NewCU->getUniqueID()));
+    else
+      NewCU->addSectionDelta(
+          Die, dwarf::DW_AT_GNU_pubtypes,
+          Asm->GetTempSymbol("gnu_pubtypes", NewCU->getUniqueID()),
+          DwarfGnuPubTypesSectionSym);
+  }
+
+  // Flag if we've emitted any ranges and their location for the compile unit.
+  if (DebugRangeSymbols.size()) {
+    if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+      NewCU->addSectionLabel(Die, dwarf::DW_AT_GNU_ranges_base,
+                             DwarfDebugRangeSectionSym);
+    else
+      NewCU->addUInt(Die, dwarf::DW_AT_GNU_ranges_base, dwarf::DW_FORM_data4,
+                     0);
+  }
+
   SkeletonHolder.addUnit(NewCU);
   SkeletonCUs.push_back(NewCU);