Update aosp/master LLVM for rebase to r222494.

Change-Id: Ic787f5e0124df789bd26f3f24680f45e678eef2d
diff --git a/lib/CodeGen/AsmPrinter/ARMException.cpp b/lib/CodeGen/AsmPrinter/ARMException.cpp
index 251f5ef..66c6c63 100644
--- a/lib/CodeGen/AsmPrinter/ARMException.cpp
+++ b/lib/CodeGen/AsmPrinter/ARMException.cpp
@@ -108,7 +108,7 @@
 }
 
 void ARMException::emitTypeInfos(unsigned TTypeEncoding) {
-  const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
+  const std::vector<const GlobalValue *> &TypeInfos = MMI->getTypeInfos();
   const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
 
   bool VerboseAsm = Asm->OutStreamer.isVerboseAsm();
@@ -121,9 +121,9 @@
     Entry = TypeInfos.size();
   }
 
-  for (std::vector<const GlobalVariable *>::const_reverse_iterator
+  for (std::vector<const GlobalValue *>::const_reverse_iterator
          I = TypeInfos.rbegin(), E = TypeInfos.rend(); I != E; ++I) {
-    const GlobalVariable *GV = *I;
+    const GlobalValue *GV = *I;
     if (VerboseAsm)
       Asm->OutStreamer.AddComment("TypeInfo " + Twine(Entry--));
     Asm->EmitTTypeReference(GV, TTypeEncoding);
diff --git a/lib/CodeGen/AsmPrinter/AddressPool.h b/lib/CodeGen/AsmPrinter/AddressPool.h
index 42757d7..802e050 100644
--- a/lib/CodeGen/AsmPrinter/AddressPool.h
+++ b/lib/CodeGen/AsmPrinter/AddressPool.h
@@ -7,8 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_ADDRESSPOOL_H__
-#define CODEGEN_ASMPRINTER_ADDRESSPOOL_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_ADDRESSPOOL_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_ADDRESSPOOL_H
 
 #include "llvm/ADT/DenseMap.h"
 
diff --git a/lib/CodeGen/AsmPrinter/Android.mk b/lib/CodeGen/AsmPrinter/Android.mk
index 083cc0d..cb8e96a 100644
--- a/lib/CodeGen/AsmPrinter/Android.mk
+++ b/lib/CodeGen/AsmPrinter/Android.mk
@@ -11,6 +11,7 @@
   DIEHash.cpp \
   DwarfAccelTable.cpp \
   DwarfCFIException.cpp \
+  DwarfCompileUnit.cpp \
   DwarfDebug.cpp \
   DwarfFile.cpp \
   DwarfStringPool.cpp \
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index f80fdea..8a32713 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -14,11 +14,13 @@
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "DwarfDebug.h"
 #include "DwarfException.h"
+#include "Win64Exception.h"
 #include "WinCodeViewLineTables.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Analysis/JumpInstrTableInfo.h"
+#include "llvm/CodeGen/Analysis.h"
 #include "llvm/CodeGen/GCMetadataPrinter.h"
 #include "llvm/CodeGen/MachineConstantPool.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
@@ -49,7 +51,6 @@
 #include "llvm/Target/TargetLoweringObjectFile.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
-#include "llvm/Transforms/Utils/GlobalStatus.h"
 using namespace llvm;
 
 #define DEBUG_TYPE "asm-printer"
@@ -98,11 +99,10 @@
 }
 
 AsmPrinter::AsmPrinter(TargetMachine &tm, MCStreamer &Streamer)
-  : MachineFunctionPass(ID),
-    TM(tm), MAI(tm.getMCAsmInfo()), MII(tm.getInstrInfo()),
-    OutContext(Streamer.getContext()),
-    OutStreamer(Streamer),
-    LastMI(nullptr), LastFn(0), Counter(~0U), SetCounter(0) {
+    : MachineFunctionPass(ID), TM(tm), MAI(tm.getMCAsmInfo()),
+      MII(tm.getSubtargetImpl()->getInstrInfo()),
+      OutContext(Streamer.getContext()), OutStreamer(Streamer), LastMI(nullptr),
+      LastFn(0), Counter(~0U), SetCounter(0) {
   DD = nullptr; MMI = nullptr; LI = nullptr; MF = nullptr;
   CurrentFnSym = CurrentFnSymForSize = nullptr;
   GCMetadataPrinters = nullptr;
@@ -129,12 +129,12 @@
 }
 
 const TargetLoweringObjectFile &AsmPrinter::getObjFileLowering() const {
-  return TM.getTargetLowering()->getObjFileLowering();
+  return TM.getSubtargetImpl()->getTargetLowering()->getObjFileLowering();
 }
 
 /// getDataLayout - Return information about data layout.
 const DataLayout &AsmPrinter::getDataLayout() const {
-  return *TM.getDataLayout();
+  return *TM.getSubtargetImpl()->getDataLayout();
 }
 
 const MCSubtargetInfo &AsmPrinter::getSubtargetInfo() const {
@@ -173,9 +173,9 @@
   const_cast<TargetLoweringObjectFile&>(getObjFileLowering())
     .Initialize(OutContext, TM);
 
-  OutStreamer.InitSections();
+  OutStreamer.InitSections(false);
 
-  Mang = new Mangler(TM.getDataLayout());
+  Mang = new Mangler(TM.getSubtargetImpl()->getDataLayout());
 
   // Emit the version-min deplyment target directive if needed.
   //
@@ -222,14 +222,12 @@
   }
 
   if (MAI->doesSupportDebugInformation()) {
-    if (Triple(TM.getTargetTriple()).isKnownWindowsMSVCEnvironment()) {
+    if (Triple(TM.getTargetTriple()).isKnownWindowsMSVCEnvironment())
       Handlers.push_back(HandlerInfo(new WinCodeViewLineTables(this),
                                      DbgTimerName,
                                      CodeViewLineTablesGroupName));
-    } else {
-      DD = new DwarfDebug(this, &M);
-      Handlers.push_back(HandlerInfo(DD, DbgTimerName, DWARFGroupName));
-    }
+    DD = new DwarfDebug(this, &M);
+    Handlers.push_back(HandlerInfo(DD, DbgTimerName, DWARFGroupName));
   }
 
   EHStreamer *ES = nullptr;
@@ -243,8 +241,13 @@
   case ExceptionHandling::ARM:
     ES = new ARMException(this);
     break;
-  case ExceptionHandling::WinEH:
-    ES = new Win64Exception(this);
+  case ExceptionHandling::ItaniumWinEH:
+    switch (MAI->getWinEHEncodingType()) {
+    default: llvm_unreachable("unsupported unwinding information encoding");
+    case WinEH::EncodingType::Itanium:
+      ES = new Win64Exception(this);
+      break;
+    }
     break;
   }
   if (ES)
@@ -253,33 +256,10 @@
 }
 
 static bool canBeHidden(const GlobalValue *GV, const MCAsmInfo &MAI) {
-  GlobalValue::LinkageTypes Linkage = GV->getLinkage();
-  if (Linkage != GlobalValue::LinkOnceODRLinkage)
-    return false;
-
   if (!MAI.hasWeakDefCanBeHiddenDirective())
     return false;
 
-  if (GV->hasUnnamedAddr())
-    return true;
-
-  // This is only used for MachO, so right now it doesn't really matter how
-  // we handle alias. Revisit this once the MachO linker implements aliases.
-  if (isa<GlobalAlias>(GV))
-    return false;
-
-  // If it is a non constant variable, it needs to be uniqued across shared
-  // objects.
-  if (const GlobalVariable *Var = dyn_cast<GlobalVariable>(GV)) {
-    if (!Var->isConstant())
-      return false;
-  }
-
-  GlobalStatus GS;
-  if (!GlobalStatus::analyzeGlobal(GV, GS) && !GS.IsCompared)
-    return true;
-
-  return false;
+  return canBeOmittedFromSymbolTable(GV);
 }
 
 void AsmPrinter::EmitLinkage(const GlobalValue *GV, MCSymbol *GVSym) const {
@@ -361,7 +341,7 @@
 
   SectionKind GVKind = TargetLoweringObjectFile::getKindForGlobal(GV, TM);
 
-  const DataLayout *DL = TM.getDataLayout();
+  const DataLayout *DL = TM.getSubtargetImpl()->getDataLayout();
   uint64_t Size = DL->getTypeAllocSize(GV->getType()->getElementType());
 
   // If the alignment is specified, we *must* obey it.  Overaligning a global
@@ -578,20 +558,24 @@
   // We assume a single instruction only has a spill or reload, not
   // both.
   const MachineMemOperand *MMO;
-  if (TM.getInstrInfo()->isLoadFromStackSlotPostFE(&MI, FI)) {
+  if (TM.getSubtargetImpl()->getInstrInfo()->isLoadFromStackSlotPostFE(&MI,
+                                                                       FI)) {
     if (FrameInfo->isSpillSlotObjectIndex(FI)) {
       MMO = *MI.memoperands_begin();
       CommentOS << MMO->getSize() << "-byte Reload\n";
     }
-  } else if (TM.getInstrInfo()->hasLoadFromStackSlot(&MI, MMO, FI)) {
+  } else if (TM.getSubtargetImpl()->getInstrInfo()->hasLoadFromStackSlot(
+                 &MI, MMO, FI)) {
     if (FrameInfo->isSpillSlotObjectIndex(FI))
       CommentOS << MMO->getSize() << "-byte Folded Reload\n";
-  } else if (TM.getInstrInfo()->isStoreToStackSlotPostFE(&MI, FI)) {
+  } else if (TM.getSubtargetImpl()->getInstrInfo()->isStoreToStackSlotPostFE(
+                 &MI, FI)) {
     if (FrameInfo->isSpillSlotObjectIndex(FI)) {
       MMO = *MI.memoperands_begin();
       CommentOS << MMO->getSize() << "-byte Spill\n";
     }
-  } else if (TM.getInstrInfo()->hasStoreToStackSlot(&MI, MMO, FI)) {
+  } else if (TM.getSubtargetImpl()->getInstrInfo()->hasStoreToStackSlot(
+                 &MI, MMO, FI)) {
     if (FrameInfo->isSpillSlotObjectIndex(FI))
       CommentOS << MMO->getSize() << "-byte Folded Spill\n";
   }
@@ -605,8 +589,9 @@
 /// that is an implicit def.
 void AsmPrinter::emitImplicitDef(const MachineInstr *MI) const {
   unsigned RegNo = MI->getOperand(0).getReg();
-  OutStreamer.AddComment(Twine("implicit-def: ") +
-                         TM.getRegisterInfo()->getName(RegNo));
+  OutStreamer.AddComment(
+      Twine("implicit-def: ") +
+      TM.getSubtargetImpl()->getRegisterInfo()->getName(RegNo));
   OutStreamer.AddBlankLine();
 }
 
@@ -616,7 +601,7 @@
     const MachineOperand &Op = MI->getOperand(i);
     assert(Op.isReg() && "KILL instruction must have only register operands");
     Str += ' ';
-    Str += AP.TM.getRegisterInfo()->getName(Op.getReg());
+    Str += AP.TM.getSubtargetImpl()->getRegisterInfo()->getName(Op.getReg());
     Str += (Op.isDef() ? "<def>" : "<kill>");
   }
   AP.OutStreamer.AddComment(Str);
@@ -627,21 +612,27 @@
 /// of DBG_VALUE, returning true if it was able to do so.  A false return
 /// means the target will need to handle MI in EmitInstruction.
 static bool emitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP) {
-  // This code handles only the 3-operand target-independent form.
-  if (MI->getNumOperands() != 3)
+  // This code handles only the 4-operand target-independent form.
+  if (MI->getNumOperands() != 4)
     return false;
 
   SmallString<128> Str;
   raw_svector_ostream OS(Str);
   OS << "DEBUG_VALUE: ";
 
-  DIVariable V(MI->getOperand(2).getMetadata());
+  DIVariable V = MI->getDebugVariable();
   if (V.getContext().isSubprogram()) {
     StringRef Name = DISubprogram(V.getContext()).getDisplayName();
     if (!Name.empty())
       OS << Name << ":";
   }
-  OS << V.getName() << " <- ";
+  OS << V.getName();
+
+  DIExpression Expr = MI->getDebugExpression();
+  if (Expr.isVariablePiece())
+    OS << " [piece offset=" << Expr.getPieceOffset()
+       << " size=" << Expr.getPieceSize() << "]";
+  OS << " <- ";
 
   // The second operand is only an offset if it's an immediate.
   bool Deref = MI->getOperand(0).isReg() && MI->getOperand(1).isImm();
@@ -672,7 +663,8 @@
       Reg = MI->getOperand(0).getReg();
     } else {
       assert(MI->getOperand(0).isFI() && "Unknown operand type");
-      const TargetFrameLowering *TFI = AP.TM.getFrameLowering();
+      const TargetFrameLowering *TFI =
+          AP.TM.getSubtargetImpl()->getFrameLowering();
       Offset += TFI->getFrameIndexReference(*AP.MF,
                                             MI->getOperand(0).getIndex(), Reg);
       Deref = true;
@@ -686,7 +678,7 @@
     }
     if (Deref)
       OS << '[';
-    OS << AP.TM.getRegisterInfo()->getName(Reg);
+    OS << AP.TM.getSubtargetImpl()->getRegisterInfo()->getName(Reg);
   }
 
   if (Deref)
@@ -709,8 +701,8 @@
 }
 
 bool AsmPrinter::needsSEHMoves() {
-  return MAI->getExceptionHandlingType() == ExceptionHandling::WinEH &&
-    MF->getFunction()->needsUnwindTableEntry();
+  return MAI->getExceptionHandlingType() == ExceptionHandling::ItaniumWinEH &&
+         MF->getFunction()->needsUnwindTableEntry();
 }
 
 void AsmPrinter::emitCFIInstruction(const MachineInstr &MI) {
@@ -722,9 +714,6 @@
   if (needsCFIMoves() == CFI_M_None)
     return;
 
-  if (MMI->getCompactUnwindEncoding() != 0)
-    OutStreamer.EmitCompactUnwindEncoding(MMI->getCompactUnwindEncoding());
-
   const MachineModuleInfo &MMI = MF->getMMI();
   const std::vector<MCCFIInstruction> &Instrs = MMI.getFrameInstructions();
   unsigned CFIIndex = MI.getOperand(0).getCFIIndex();
@@ -742,12 +731,10 @@
 
   // Print out code for the function.
   bool HasAnyRealCode = false;
-  const MachineInstr *LastMI = nullptr;
   for (auto &MBB : *MF) {
     // Print a label for the basic block.
     EmitBasicBlockStart(MBB);
     for (auto &MI : MBB) {
-      LastMI = &MI;
 
       // Print the assembly for the instruction.
       if (!MI.isPosition() && !MI.isImplicitDef() && !MI.isKill() &&
@@ -804,26 +791,22 @@
         }
       }
     }
-  }
 
-  // If the last instruction was a prolog label, then we have a situation where
-  // we emitted a prolog but no function body. This results in the ending prolog
-  // label equaling the end of function label and an invalid "row" in the
-  // FDE. We need to emit a noop in this situation so that the FDE's rows are
-  // valid.
-  bool RequiresNoop = LastMI && LastMI->isCFIInstruction();
+    EmitBasicBlockEnd(MBB);
+  }
 
   // If the function is empty and the object file uses .subsections_via_symbols,
   // then we need to emit *something* to the function body to prevent the
   // labels from collapsing together.  Just emit a noop.
-  if ((MAI->hasSubsectionsViaSymbols() && !HasAnyRealCode) || RequiresNoop) {
+  if ((MAI->hasSubsectionsViaSymbols() && !HasAnyRealCode)) {
     MCInst Noop;
-    TM.getInstrInfo()->getNoopForMachoTarget(Noop);
-    if (Noop.getOpcode()) {
-      OutStreamer.AddComment("avoids zero-length function");
+    TM.getSubtargetImpl()->getInstrInfo()->getNoopForMachoTarget(Noop);
+    OutStreamer.AddComment("avoids zero-length function");
+
+    // Targets can opt-out of emitting the noop here by leaving the opcode
+    // unspecified.
+    if (Noop.getOpcode())
       OutStreamer.EmitInstruction(Noop, getSubtargetInfo());
-    } else  // Target not mc-ized yet.
-      OutStreamer.EmitRawText(StringRef("\tnop\n"));
   }
 
   const Function *F = MF->getFunction();
@@ -895,17 +878,18 @@
     unsigned Arch = Triple(getTargetTriple()).getArch();
     bool IsThumb = (Arch == Triple::thumb || Arch == Triple::thumbeb);
     MCInst TrapInst;
-    TM.getInstrInfo()->getTrap(TrapInst);
+    TM.getSubtargetImpl()->getInstrInfo()->getTrap(TrapInst);
+    unsigned LogAlignment = llvm::Log2_64(JITI->entryByteAlignment());
+
+    // Emit the right section for these functions.
+    OutStreamer.SwitchSection(OutContext.getObjectFileInfo()->getTextSection());
     for (const auto &KV : JITI->getTables()) {
       uint64_t Count = 0;
       for (const auto &FunPair : KV.second) {
         // Emit the function labels to make this be a function entry point.
         MCSymbol *FunSym =
           OutContext.GetOrCreateSymbol(FunPair.second->getName());
-        OutStreamer.EmitSymbolAttribute(FunSym, MCSA_Global);
-        // FIXME: JumpTableInstrInfo should store information about the required
-        // alignment of table entries and the size of the padding instruction.
-        EmitAlignment(3);
+        EmitAlignment(LogAlignment);
         if (IsThumb)
           OutStreamer.EmitThumbFunc(FunSym);
         if (MAI->hasDotTypeDotSizeDirective())
@@ -920,16 +904,16 @@
         const MCSymbolRefExpr *TargetSymRef =
           MCSymbolRefExpr::Create(TargetSymbol, MCSymbolRefExpr::VK_PLT,
                                   OutContext);
-        TM.getInstrInfo()->getUnconditionalBranch(JumpToFun, TargetSymRef);
+        TM.getSubtargetImpl()->getInstrInfo()->getUnconditionalBranch(
+            JumpToFun, TargetSymRef);
         OutStreamer.EmitInstruction(JumpToFun, getSubtargetInfo());
         ++Count;
       }
 
       // Emit enough padding instructions to fill up to the next power of two.
-      // This assumes that the trap instruction takes 8 bytes or fewer.
       uint64_t Remaining = NextPowerOf2(Count) - Count;
       for (uint64_t C = 0; C < Remaining; ++C) {
-        EmitAlignment(3);
+        EmitAlignment(LogAlignment);
         OutStreamer.EmitInstruction(TrapInst, getSubtargetInfo());
       }
 
@@ -976,24 +960,21 @@
     }
   }
 
-  if (MAI->hasSetDirective()) {
-    OutStreamer.AddBlankLine();
-    for (const auto &Alias : M.aliases()) {
-      MCSymbol *Name = getSymbol(&Alias);
+  OutStreamer.AddBlankLine();
+  for (const auto &Alias : M.aliases()) {
+    MCSymbol *Name = getSymbol(&Alias);
 
-      if (Alias.hasExternalLinkage() || !MAI->getWeakRefDirective())
-        OutStreamer.EmitSymbolAttribute(Name, MCSA_Global);
-      else if (Alias.hasWeakLinkage() || Alias.hasLinkOnceLinkage())
-        OutStreamer.EmitSymbolAttribute(Name, MCSA_WeakReference);
-      else
-        assert(Alias.hasLocalLinkage() && "Invalid alias linkage");
+    if (Alias.hasExternalLinkage() || !MAI->getWeakRefDirective())
+      OutStreamer.EmitSymbolAttribute(Name, MCSA_Global);
+    else if (Alias.hasWeakLinkage() || Alias.hasLinkOnceLinkage())
+      OutStreamer.EmitSymbolAttribute(Name, MCSA_WeakReference);
+    else
+      assert(Alias.hasLocalLinkage() && "Invalid alias linkage");
 
-      EmitVisibility(Name, Alias.getVisibility());
+    EmitVisibility(Name, Alias.getVisibility());
 
-      // Emit the directives as assignments aka .set:
-      OutStreamer.EmitAssignment(Name,
-                                 lowerConstant(Alias.getAliasee(), *this));
-    }
+    // Emit the directives as assignments aka .set:
+    OutStreamer.EmitAssignment(Name, lowerConstant(Alias.getAliasee(), *this));
   }
 
   GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
@@ -1062,23 +1043,14 @@
     const MachineConstantPoolEntry &CPE = CP[i];
     unsigned Align = CPE.getAlignment();
 
-    SectionKind Kind;
-    switch (CPE.getRelocationInfo()) {
-    default: llvm_unreachable("Unknown section kind");
-    case 2: Kind = SectionKind::getReadOnlyWithRel(); break;
-    case 1:
-      Kind = SectionKind::getReadOnlyWithRelLocal();
-      break;
-    case 0:
-    switch (TM.getDataLayout()->getTypeAllocSize(CPE.getType())) {
-    case 4:  Kind = SectionKind::getMergeableConst4(); break;
-    case 8:  Kind = SectionKind::getMergeableConst8(); break;
-    case 16: Kind = SectionKind::getMergeableConst16();break;
-    default: Kind = SectionKind::getMergeableConst(); break;
-    }
-    }
+    SectionKind Kind =
+        CPE.getSectionKind(TM.getSubtargetImpl()->getDataLayout());
 
-    const MCSection *S = getObjFileLowering().getSectionForConstant(Kind);
+    const Constant *C = nullptr;
+    if (!CPE.isMachineConstantPoolEntry())
+      C = CPE.Val.ConstVal;
+
+    const MCSection *S = getObjFileLowering().getSectionForConstant(Kind, C);
 
     // The number of sections are small, just do a linear search from the
     // last section to the first.
@@ -1101,13 +1073,22 @@
   }
 
   // Now print stuff into the calculated sections.
+  const MCSection *CurSection = nullptr;
+  unsigned Offset = 0;
   for (unsigned i = 0, e = CPSections.size(); i != e; ++i) {
-    OutStreamer.SwitchSection(CPSections[i].S);
-    EmitAlignment(Log2_32(CPSections[i].Alignment));
-
-    unsigned Offset = 0;
     for (unsigned j = 0, ee = CPSections[i].CPEs.size(); j != ee; ++j) {
       unsigned CPI = CPSections[i].CPEs[j];
+      MCSymbol *Sym = GetCPISymbol(CPI);
+      if (!Sym->isUndefined())
+        continue;
+
+      if (CurSection != CPSections[i].S) {
+        OutStreamer.SwitchSection(CPSections[i].S);
+        EmitAlignment(Log2_32(CPSections[i].Alignment));
+        CurSection = CPSections[i].S;
+        Offset = 0;
+      }
+
       MachineConstantPoolEntry CPE = CP[CPI];
 
       // Emit inter-object padding for alignment.
@@ -1116,9 +1097,10 @@
       OutStreamer.EmitZeros(NewOffset - Offset);
 
       Type *Ty = CPE.getType();
-      Offset = NewOffset + TM.getDataLayout()->getTypeAllocSize(Ty);
-      OutStreamer.EmitLabel(GetCPISymbol(CPI));
+      Offset = NewOffset +
+               TM.getSubtargetImpl()->getDataLayout()->getTypeAllocSize(Ty);
 
+      OutStreamer.EmitLabel(Sym);
       if (CPE.isMachineConstantPoolEntry())
         EmitMachineConstantPoolValue(CPE.Val.MachineCPVal);
       else
@@ -1131,7 +1113,7 @@
 /// by the current function to the current output stream.
 ///
 void AsmPrinter::EmitJumpTableInfo() {
-  const DataLayout *DL = MF->getTarget().getDataLayout();
+  const DataLayout *DL = MF->getSubtarget().getDataLayout();
   const MachineJumpTableInfo *MJTI = MF->getJumpTableInfo();
   if (!MJTI) return;
   if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_Inline) return;
@@ -1156,12 +1138,14 @@
   } else {
     // Otherwise, drop it in the readonly section.
     const MCSection *ReadOnlySection =
-      getObjFileLowering().getSectionForConstant(SectionKind::getReadOnly());
+        getObjFileLowering().getSectionForConstant(SectionKind::getReadOnly(),
+                                                   /*C=*/nullptr);
     OutStreamer.SwitchSection(ReadOnlySection);
     JTInDiffSection = true;
   }
 
-  EmitAlignment(Log2_32(MJTI->getEntryAlignment(*TM.getDataLayout())));
+  EmitAlignment(Log2_32(
+      MJTI->getEntryAlignment(*TM.getSubtargetImpl()->getDataLayout())));
 
   // Jump tables in code sections are marked with a data_region directive
   // where that's supported.
@@ -1174,17 +1158,17 @@
     // If this jump table was deleted, ignore it.
     if (JTBBs.empty()) continue;
 
-    // For the EK_LabelDifference32 entry, if the target supports .set, emit a
-    // .set directive for each unique entry.  This reduces the number of
-    // relocations the assembler will generate for the jump table.
+    // For the EK_LabelDifference32 entry, if using .set avoids a relocation,
+    /// emit a .set directive for each unique entry.
     if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32 &&
-        MAI->hasSetDirective()) {
+        MAI->doesSetDirectiveSuppressesReloc()) {
       SmallPtrSet<const MachineBasicBlock*, 16> EmittedSets;
-      const TargetLowering *TLI = TM.getTargetLowering();
+      const TargetLowering *TLI = TM.getSubtargetImpl()->getTargetLowering();
       const MCExpr *Base = TLI->getPICJumpTableRelocBaseExpr(MF,JTI,OutContext);
       for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii) {
         const MachineBasicBlock *MBB = JTBBs[ii];
-        if (!EmittedSets.insert(MBB)) continue;
+        if (!EmittedSets.insert(MBB).second)
+          continue;
 
         // .set LJTSet, LBB32-base
         const MCExpr *LHS =
@@ -1223,8 +1207,9 @@
   case MachineJumpTableInfo::EK_Inline:
     llvm_unreachable("Cannot emit EK_Inline jump table entry");
   case MachineJumpTableInfo::EK_Custom32:
-    Value = TM.getTargetLowering()->LowerCustomJumpTableEntry(MJTI, MBB, UID,
-                                                              OutContext);
+    Value =
+        TM.getSubtargetImpl()->getTargetLowering()->LowerCustomJumpTableEntry(
+            MJTI, MBB, UID, OutContext);
     break;
   case MachineJumpTableInfo::EK_BlockAddress:
     // EK_BlockAddress - Each entry is a plain address of block, e.g.:
@@ -1250,34 +1235,30 @@
   }
 
   case MachineJumpTableInfo::EK_LabelDifference32: {
-    // EK_LabelDifference32 - Each entry is the address of the block minus
-    // the address of the jump table.  This is used for PIC jump tables where
-    // gprel32 is not supported.  e.g.:
+    // Each entry is the address of the block minus the address of the jump
+    // table. This is used for PIC jump tables where gprel32 is not supported.
+    // e.g.:
     //      .word LBB123 - LJTI1_2
-    // If the .set directive is supported, this is emitted as:
+    // If the .set directive avoids relocations, this is emitted as:
     //      .set L4_5_set_123, LBB123 - LJTI1_2
     //      .word L4_5_set_123
-
-    // If we have emitted set directives for the jump table entries, print
-    // them rather than the entries themselves.  If we're emitting PIC, then
-    // emit the table entries as differences between two text section labels.
-    if (MAI->hasSetDirective()) {
-      // If we used .set, reference the .set's symbol.
+    if (MAI->doesSetDirectiveSuppressesReloc()) {
       Value = MCSymbolRefExpr::Create(GetJTSetSymbol(UID, MBB->getNumber()),
                                       OutContext);
       break;
     }
-    // Otherwise, use the difference as the jump table entry.
     Value = MCSymbolRefExpr::Create(MBB->getSymbol(), OutContext);
-    const MCExpr *JTI = MCSymbolRefExpr::Create(GetJTISymbol(UID), OutContext);
-    Value = MCBinaryExpr::CreateSub(Value, JTI, OutContext);
+    const TargetLowering *TLI = TM.getSubtargetImpl()->getTargetLowering();
+    const MCExpr *Base = TLI->getPICJumpTableRelocBaseExpr(MF, UID, OutContext);
+    Value = MCBinaryExpr::CreateSub(Value, Base, OutContext);
     break;
   }
   }
 
   assert(Value && "Unknown entry kind!");
 
-  unsigned EntrySize = MJTI->getEntrySize(*TM.getDataLayout());
+  unsigned EntrySize =
+      MJTI->getEntrySize(*TM.getSubtargetImpl()->getDataLayout());
   OutStreamer.EmitValue(Value, EntrySize);
 }
 
@@ -1387,7 +1368,7 @@
   }
 
   // Emit the function pointers in the target-specific order
-  const DataLayout *DL = TM.getDataLayout();
+  const DataLayout *DL = TM.getSubtargetImpl()->getDataLayout();
   unsigned Align = Log2_32(DL->getPointerPrefAlignment());
   std::stable_sort(Structors.begin(), Structors.end(),
                    [](const Structor &L,
@@ -1450,9 +1431,9 @@
   OutStreamer.EmitIntValue(Value, 4);
 }
 
-/// EmitLabelDifference - Emit something like ".long Hi-Lo" where the size
-/// in bytes of the directive is specified by Size and Hi/Lo specify the
-/// labels.  This implicitly uses .set if it is available.
+/// Emit something like ".long Hi-Lo" where the size in bytes of the directive
+/// is specified by Size and Hi/Lo specify the labels. This implicitly uses
+/// .set if it avoids relocations.
 void AsmPrinter::EmitLabelDifference(const MCSymbol *Hi, const MCSymbol *Lo,
                                      unsigned Size) const {
   // Get the Hi-Lo expression.
@@ -1461,7 +1442,7 @@
                             MCSymbolRefExpr::Create(Lo, OutContext),
                             OutContext);
 
-  if (!MAI->hasSetDirective()) {
+  if (!MAI->doesSetDirectiveSuppressesReloc()) {
     OutStreamer.EmitValue(Diff, Size);
     return;
   }
@@ -1472,36 +1453,6 @@
   OutStreamer.EmitSymbolValue(SetLabel, Size);
 }
 
-/// EmitLabelOffsetDifference - Emit something like ".long Hi+Offset-Lo"
-/// where the size in bytes of the directive is specified by Size and Hi/Lo
-/// specify the labels.  This implicitly uses .set if it is available.
-void AsmPrinter::EmitLabelOffsetDifference(const MCSymbol *Hi, uint64_t Offset,
-                                           const MCSymbol *Lo,
-                                           unsigned Size) const {
-
-  // Emit Hi+Offset - Lo
-  // Get the Hi+Offset expression.
-  const MCExpr *Plus =
-    MCBinaryExpr::CreateAdd(MCSymbolRefExpr::Create(Hi, OutContext),
-                            MCConstantExpr::Create(Offset, OutContext),
-                            OutContext);
-
-  // Get the Hi+Offset-Lo expression.
-  const MCExpr *Diff =
-    MCBinaryExpr::CreateSub(Plus,
-                            MCSymbolRefExpr::Create(Lo, OutContext),
-                            OutContext);
-
-  if (!MAI->hasSetDirective())
-    OutStreamer.EmitValue(Diff, Size);
-  else {
-    // Otherwise, emit with .set (aka assignment).
-    MCSymbol *SetLabel = GetTempSymbol("set", SetCounter++);
-    OutStreamer.EmitAssignment(SetLabel, Diff);
-    OutStreamer.EmitSymbolValue(SetLabel, Size);
-  }
-}
-
 /// EmitLabelPlusOffset - Emit something like ".long Label+Offset"
 /// where the size in bytes of the directive is specified by Size and Label
 /// specifies the label.  This implicitly uses .set if it is available.
@@ -1531,7 +1482,9 @@
 // if required for correctness.
 //
 void AsmPrinter::EmitAlignment(unsigned NumBits, const GlobalObject *GV) const {
-  if (GV) NumBits = getGVAlignmentLog2(GV, *TM.getDataLayout(), NumBits);
+  if (GV)
+    NumBits = getGVAlignmentLog2(GV, *TM.getSubtargetImpl()->getDataLayout(),
+                                 NumBits);
 
   if (NumBits == 0) return;   // 1-byte aligned: no need to emit alignment.
 
@@ -1577,8 +1530,8 @@
     // If the code isn't optimized, there may be outstanding folding
     // opportunities. Attempt to fold the expression using DataLayout as a
     // last resort before giving up.
-    if (Constant *C =
-          ConstantFoldConstantExpression(CE, AP.TM.getDataLayout()))
+    if (Constant *C = ConstantFoldConstantExpression(
+            CE, AP.TM.getSubtargetImpl()->getDataLayout()))
       if (C != CE)
         return lowerConstant(C, AP);
 
@@ -1592,7 +1545,7 @@
       report_fatal_error(OS.str());
     }
   case Instruction::GetElementPtr: {
-    const DataLayout &DL = *AP.TM.getDataLayout();
+    const DataLayout &DL = *AP.TM.getSubtargetImpl()->getDataLayout();
     // Generate a symbolic expression for the byte address
     APInt OffsetAI(DL.getPointerTypeSizeInBits(CE->getType()), 0);
     cast<GEPOperator>(CE)->accumulateConstantOffset(DL, OffsetAI);
@@ -1616,7 +1569,7 @@
     return lowerConstant(CE->getOperand(0), AP);
 
   case Instruction::IntToPtr: {
-    const DataLayout &DL = *AP.TM.getDataLayout();
+    const DataLayout &DL = *AP.TM.getSubtargetImpl()->getDataLayout();
     // Handle casts to pointers by changing them into casts to the appropriate
     // integer type.  This promotes constant folding and simplifies this code.
     Constant *Op = CE->getOperand(0);
@@ -1626,7 +1579,7 @@
   }
 
   case Instruction::PtrToInt: {
-    const DataLayout &DL = *AP.TM.getDataLayout();
+    const DataLayout &DL = *AP.TM.getSubtargetImpl()->getDataLayout();
     // Support only foldable casts to/from pointers that can be eliminated by
     // changing the pointer to the appropriately sized integer type.
     Constant *Op = CE->getOperand(0);
@@ -1699,7 +1652,8 @@
   if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
     if (CI->getBitWidth() > 64) return -1;
 
-    uint64_t Size = TM.getDataLayout()->getTypeAllocSize(V->getType());
+    uint64_t Size =
+        TM.getSubtargetImpl()->getDataLayout()->getTypeAllocSize(V->getType());
     uint64_t Value = CI->getZExtValue();
 
     // Make sure the constant is at least 8 bits long and has a power
@@ -1743,7 +1697,9 @@
   // See if we can aggregate this into a .fill, if so, emit it as such.
   int Value = isRepeatedByteSequence(CDS, AP.TM);
   if (Value != -1) {
-    uint64_t Bytes = AP.TM.getDataLayout()->getTypeAllocSize(CDS->getType());
+    uint64_t Bytes =
+        AP.TM.getSubtargetImpl()->getDataLayout()->getTypeAllocSize(
+            CDS->getType());
     // Don't emit a 1-byte object as a .fill.
     if (Bytes > 1)
       return AP.OutStreamer.EmitFill(Bytes, Value);
@@ -1793,7 +1749,7 @@
     }
   }
 
-  const DataLayout &DL = *AP.TM.getDataLayout();
+  const DataLayout &DL = *AP.TM.getSubtargetImpl()->getDataLayout();
   unsigned Size = DL.getTypeAllocSize(CDS->getType());
   unsigned EmittedSize = DL.getTypeAllocSize(CDS->getType()->getElementType()) *
                         CDS->getNumElements();
@@ -1808,7 +1764,9 @@
   int Value = isRepeatedByteSequence(CA, AP.TM);
 
   if (Value != -1) {
-    uint64_t Bytes = AP.TM.getDataLayout()->getTypeAllocSize(CA->getType());
+    uint64_t Bytes =
+        AP.TM.getSubtargetImpl()->getDataLayout()->getTypeAllocSize(
+            CA->getType());
     AP.OutStreamer.EmitFill(Bytes, Value);
   }
   else {
@@ -1821,7 +1779,7 @@
   for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
     emitGlobalConstantImpl(CV->getOperand(i), AP);
 
-  const DataLayout &DL = *AP.TM.getDataLayout();
+  const DataLayout &DL = *AP.TM.getSubtargetImpl()->getDataLayout();
   unsigned Size = DL.getTypeAllocSize(CV->getType());
   unsigned EmittedSize = DL.getTypeAllocSize(CV->getType()->getElementType()) *
                          CV->getType()->getNumElements();
@@ -1831,7 +1789,7 @@
 
 static void emitGlobalConstantStruct(const ConstantStruct *CS, AsmPrinter &AP) {
   // Print the fields in successive locations. Pad to align if needed!
-  const DataLayout *DL = AP.TM.getDataLayout();
+  const DataLayout *DL = AP.TM.getSubtargetImpl()->getDataLayout();
   unsigned Size = DL->getTypeAllocSize(CS->getType());
   const StructLayout *Layout = DL->getStructLayout(CS->getType());
   uint64_t SizeSoFar = 0;
@@ -1881,7 +1839,7 @@
 
   // PPC's long double has odd notions of endianness compared to how LLVM
   // handles it: p[0] goes first for *big* endian on PPC.
-  if (AP.TM.getDataLayout()->isBigEndian() &&
+  if (AP.TM.getSubtargetImpl()->getDataLayout()->isBigEndian() &&
       !CFP->getType()->isPPC_FP128Ty()) {
     int Chunk = API.getNumWords() - 1;
 
@@ -1900,13 +1858,13 @@
   }
 
   // Emit the tail padding for the long double.
-  const DataLayout &DL = *AP.TM.getDataLayout();
+  const DataLayout &DL = *AP.TM.getSubtargetImpl()->getDataLayout();
   AP.OutStreamer.EmitZeros(DL.getTypeAllocSize(CFP->getType()) -
                            DL.getTypeStoreSize(CFP->getType()));
 }
 
 static void emitGlobalConstantLargeInt(const ConstantInt *CI, AsmPrinter &AP) {
-  const DataLayout *DL = AP.TM.getDataLayout();
+  const DataLayout *DL = AP.TM.getSubtargetImpl()->getDataLayout();
   unsigned BitWidth = CI->getBitWidth();
 
   // Copy the value as we may massage the layout for constants whose bit width
@@ -1952,7 +1910,8 @@
     // Emit the extra bits after the 64-bits chunks.
 
     // Emit a directive that fills the expected size.
-    uint64_t Size = AP.TM.getDataLayout()->getTypeAllocSize(CI->getType());
+    uint64_t Size = AP.TM.getSubtargetImpl()->getDataLayout()->getTypeAllocSize(
+        CI->getType());
     Size -= (BitWidth / 64) * 8;
     assert(Size && Size * 8 >= ExtraBitsSize &&
            (ExtraBits & (((uint64_t)-1) >> (64 - ExtraBitsSize)))
@@ -1962,7 +1921,7 @@
 }
 
 static void emitGlobalConstantImpl(const Constant *CV, AsmPrinter &AP) {
-  const DataLayout *DL = AP.TM.getDataLayout();
+  const DataLayout *DL = AP.TM.getSubtargetImpl()->getDataLayout();
   uint64_t Size = DL->getTypeAllocSize(CV->getType());
   if (isa<ConstantAggregateZero>(CV) || isa<UndefValue>(CV))
     return AP.OutStreamer.EmitZeros(Size);
@@ -2027,7 +1986,8 @@
 
 /// EmitGlobalConstant - Print a general LLVM constant to the .s file.
 void AsmPrinter::EmitGlobalConstant(const Constant *CV) {
-  uint64_t Size = TM.getDataLayout()->getTypeAllocSize(CV->getType());
+  uint64_t Size =
+      TM.getSubtargetImpl()->getDataLayout()->getTypeAllocSize(CV->getType());
   if (Size)
     emitGlobalConstantImpl(CV, *this);
   else if (MAI->hasSubsectionsViaSymbols()) {
@@ -2056,7 +2016,7 @@
 /// GetTempSymbol - Return the MCSymbol corresponding to the assembler
 /// temporary label with the specified stem and unique ID.
 MCSymbol *AsmPrinter::GetTempSymbol(Twine Name, unsigned ID) const {
-  const DataLayout *DL = TM.getDataLayout();
+  const DataLayout *DL = TM.getSubtargetImpl()->getDataLayout();
   return OutContext.GetOrCreateSymbol(Twine(DL->getPrivateGlobalPrefix()) +
                                       Name + Twine(ID));
 }
@@ -2064,7 +2024,7 @@
 /// GetTempSymbol - Return an assembler temporary label with the specified
 /// stem.
 MCSymbol *AsmPrinter::GetTempSymbol(Twine Name) const {
-  const DataLayout *DL = TM.getDataLayout();
+  const DataLayout *DL = TM.getSubtargetImpl()->getDataLayout();
   return OutContext.GetOrCreateSymbol(Twine(DL->getPrivateGlobalPrefix())+
                                       Name);
 }
@@ -2080,7 +2040,7 @@
 
 /// GetCPISymbol - Return the symbol for the specified constant pool entry.
 MCSymbol *AsmPrinter::GetCPISymbol(unsigned CPID) const {
-  const DataLayout *DL = TM.getDataLayout();
+  const DataLayout *DL = TM.getSubtargetImpl()->getDataLayout();
   return OutContext.GetOrCreateSymbol
     (Twine(DL->getPrivateGlobalPrefix()) + "CPI" + Twine(getFunctionNumber())
      + "_" + Twine(CPID));
@@ -2094,7 +2054,7 @@
 /// GetJTSetSymbol - Return the symbol for the specified jump table .set
 /// FIXME: privatize to AsmPrinter.
 MCSymbol *AsmPrinter::GetJTSetSymbol(unsigned UID, unsigned MBBID) const {
-  const DataLayout *DL = TM.getDataLayout();
+  const DataLayout *DL = TM.getSubtargetImpl()->getDataLayout();
   return OutContext.GetOrCreateSymbol
   (Twine(DL->getPrivateGlobalPrefix()) + Twine(getFunctionNumber()) + "_" +
    Twine(UID) + "_set_" + Twine(MBBID));
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp b/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
index 02cd12b..05f6a68 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
@@ -27,6 +27,7 @@
 #include "llvm/Target/TargetLoweringObjectFile.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
 using namespace llvm;
 
 #define DEBUG_TYPE "asm-printer"
@@ -130,7 +131,7 @@
   default:
     llvm_unreachable("Invalid encoded value.");
   case dwarf::DW_EH_PE_absptr:
-    return TM.getDataLayout()->getPointerSize();
+    return TM.getSubtargetImpl()->getDataLayout()->getPointerSize();
   case dwarf::DW_EH_PE_udata2:
     return 2;
   case dwarf::DW_EH_PE_udata4:
@@ -214,13 +215,10 @@
     Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref");
 }
 
-/// Emit a dwarf register operation for describing
-/// - a small value occupying only part of a register or
-/// - a small register representing only part of a value.
-static void emitDwarfOpPiece(ByteStreamer &Streamer, unsigned SizeInBits,
-                             unsigned OffsetInBits) {
-  assert(SizeInBits > 0 && "zero-sized piece");
-  unsigned SizeOfByte = 8;
+void AsmPrinter::EmitDwarfOpPiece(ByteStreamer &Streamer, unsigned SizeInBits,
+                                  unsigned OffsetInBits) const {
+  assert(SizeInBits > 0 && "piece has size zero");
+  const unsigned SizeOfByte = 8;
   if (OffsetInBits > 0 || SizeInBits % SizeOfByte) {
     Streamer.EmitInt8(dwarf::DW_OP_bit_piece, "DW_OP_bit_piece");
     Streamer.EmitULEB128(SizeInBits, Twine(SizeInBits));
@@ -249,13 +247,13 @@
                                      unsigned PieceSizeInBits,
                                      unsigned PieceOffsetInBits) const {
   assert(MLoc.isReg() && "MLoc must be a register");
-  const TargetRegisterInfo *TRI = TM.getRegisterInfo();
+  const TargetRegisterInfo *TRI = TM.getSubtargetImpl()->getRegisterInfo();
   int Reg = TRI->getDwarfRegNum(MLoc.getReg(), false);
 
   // If this is a valid register number, emit it.
   if (Reg >= 0) {
     emitDwarfRegOp(Streamer, Reg);
-    emitDwarfOpPiece(Streamer, PieceSizeInBits, PieceOffsetInBits);
+    EmitDwarfOpPiece(Streamer, PieceSizeInBits, PieceOffsetInBits);
     return;
   }
 
@@ -266,19 +264,19 @@
     if (Reg >= 0) {
       unsigned Idx = TRI->getSubRegIndex(*SR, MLoc.getReg());
       unsigned Size = TRI->getSubRegIdxSize(Idx);
-      unsigned Offset = TRI->getSubRegIdxOffset(Idx);
+      unsigned RegOffset = TRI->getSubRegIdxOffset(Idx);
       OutStreamer.AddComment("super-register");
       emitDwarfRegOp(Streamer, Reg);
-      if (PieceOffsetInBits == Offset) {
-        emitDwarfOpPiece(Streamer, Size, Offset);
+      if (PieceOffsetInBits == RegOffset) {
+        EmitDwarfOpPiece(Streamer, Size, RegOffset);
       } else {
         // If this is part of a variable in a sub-register at a
         // non-zero offset, we need to manually shift the value into
         // place, since the DW_OP_piece describes the part of the
         // variable, not the position of the subregister.
-        emitDwarfOpPiece(Streamer, Size, PieceOffsetInBits);
-        if (Offset)
-          emitDwarfOpShr(Streamer, Offset);
+        if (RegOffset)
+          emitDwarfOpShr(Streamer, RegOffset);
+        EmitDwarfOpPiece(Streamer, Size, PieceOffsetInBits);
       }
       return;
     }
@@ -312,7 +310,7 @@
     if (Reg >= 0 && Intersection.any()) {
       OutStreamer.AddComment("sub-register");
       emitDwarfRegOp(Streamer, Reg);
-      emitDwarfOpPiece(Streamer, Size, Offset == CurPos ? 0 : Offset);
+      EmitDwarfOpPiece(Streamer, Size, Offset == CurPos ? 0 : Offset);
       CurPos = Offset + Size;
 
       // Mark it as emitted.
@@ -331,7 +329,7 @@
 void AsmPrinter::EmitDwarfRegOp(ByteStreamer &Streamer,
                                 const MachineLocation &MLoc,
                                 bool Indirect) const {
-  const TargetRegisterInfo *TRI = TM.getRegisterInfo();
+  const TargetRegisterInfo *TRI = TM.getSubtargetImpl()->getRegisterInfo();
   int Reg = TRI->getDwarfRegNum(MLoc.getReg(), false);
   if (Reg < 0) {
     // We assume that pointers are always in an addressable register.
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinterHandler.h b/lib/CodeGen/AsmPrinter/AsmPrinterHandler.h
index 2825367..31867dd 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinterHandler.h
+++ b/lib/CodeGen/AsmPrinter/AsmPrinterHandler.h
@@ -12,8 +12,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_ASMPRINTERHANDLER_H__
-#define CODEGEN_ASMPRINTER_ASMPRINTERHANDLER_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_ASMPRINTERHANDLER_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_ASMPRINTERHANDLER_H
 
 #include "llvm/Support/DataTypes.h"
 
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp b/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
index 46ee0c8..cca5f22 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp
@@ -33,6 +33,7 @@
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
 using namespace llvm;
 
@@ -110,14 +111,14 @@
     HasDiagHandler = true;
   }
 
-  MemoryBuffer *Buffer;
+  std::unique_ptr<MemoryBuffer> Buffer;
   if (isNullTerminated)
     Buffer = MemoryBuffer::getMemBuffer(Str, "<inline asm>");
   else
     Buffer = MemoryBuffer::getMemBufferCopy(Str, "<inline asm>");
 
   // Tell SrcMgr about this buffer, it takes ownership of the buffer.
-  SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
+  SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
 
   std::unique_ptr<MCAsmParser> Parser(
       createMCAsmParser(SrcMgr, OutContext, OutStreamer, *MAI));
@@ -146,6 +147,10 @@
                        " we don't have an asm parser for this target\n");
   Parser->setAssemblerDialect(Dialect);
   Parser->setTargetParser(*TAP.get());
+  if (MF) {
+    const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
+    TAP->SetFrameRegister(TRI->getFrameRegister(*MF));
+  }
 
   // Don't implicitly switch to the text section before the asm.
   int Res = Parser->Run(/*NoInitialTextSection*/ true,
@@ -500,7 +505,7 @@
 /// for their own strange codes.
 void AsmPrinter::PrintSpecial(const MachineInstr *MI, raw_ostream &OS,
                               const char *Code) const {
-  const DataLayout *DL = TM.getDataLayout();
+  const DataLayout *DL = TM.getSubtargetImpl()->getDataLayout();
   if (!strcmp(Code, "private")) {
     OS << DL->getPrivateGlobalPrefix();
   } else if (!strcmp(Code, "comment")) {
diff --git a/lib/CodeGen/AsmPrinter/ByteStreamer.h b/lib/CodeGen/AsmPrinter/ByteStreamer.h
index 6c01d65..0cc8353 100644
--- a/lib/CodeGen/AsmPrinter/ByteStreamer.h
+++ b/lib/CodeGen/AsmPrinter/ByteStreamer.h
@@ -12,8 +12,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_CODEGEN_BYTESTREAMER_H
-#define LLVM_CODEGEN_BYTESTREAMER_H
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_BYTESTREAMER_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_BYTESTREAMER_H
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/CodeGen/AsmPrinter.h"
diff --git a/lib/CodeGen/AsmPrinter/CMakeLists.txt b/lib/CodeGen/AsmPrinter/CMakeLists.txt
index f555f21..e6b7d64 100644
--- a/lib/CodeGen/AsmPrinter/CMakeLists.txt
+++ b/lib/CodeGen/AsmPrinter/CMakeLists.txt
@@ -9,6 +9,7 @@
   DIEHash.cpp
   DwarfAccelTable.cpp
   DwarfCFIException.cpp
+  DwarfCompileUnit.cpp
   DwarfDebug.cpp
   DwarfFile.cpp
   DwarfStringPool.cpp
diff --git a/lib/CodeGen/AsmPrinter/DIE.cpp b/lib/CodeGen/AsmPrinter/DIE.cpp
index c3dcd9c..50ea369 100644
--- a/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -12,12 +12,15 @@
 //===----------------------------------------------------------------------===//
 
 #include "DIE.h"
+
+#include "DwarfCompileUnit.h"
 #include "DwarfDebug.h"
 #include "DwarfUnit.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Support/Debug.h"
@@ -370,6 +373,29 @@
 // DIEEntry Implementation
 //===----------------------------------------------------------------------===//
 
+/// Emit something like ".long Hi+Offset-Lo" where the size in bytes of the
+/// directive is specified by Size and Hi/Lo specify the labels.
+static void emitLabelOffsetDifference(MCStreamer &Streamer, const MCSymbol *Hi,
+                                      uint64_t Offset, const MCSymbol *Lo,
+                                      unsigned Size) {
+  MCContext &Context = Streamer.getContext();
+
+  // Emit Hi+Offset - Lo
+  // Get the Hi+Offset expression.
+  const MCExpr *Plus =
+      MCBinaryExpr::CreateAdd(MCSymbolRefExpr::Create(Hi, Context),
+                              MCConstantExpr::Create(Offset, Context), Context);
+
+  // Get the Hi+Offset-Lo expression.
+  const MCExpr *Diff = MCBinaryExpr::CreateSub(
+      Plus, MCSymbolRefExpr::Create(Lo, Context), Context);
+
+  // Otherwise, emit with .set (aka assignment).
+  MCSymbol *SetLabel = Context.CreateTempSymbol();
+  Streamer.EmitAssignment(SetLabel, Diff);
+  Streamer.EmitSymbolValue(SetLabel, Size);
+}
+
 /// EmitValue - Emit debug information entry offset.
 ///
 void DIEEntry::EmitValue(AsmPrinter *AP, dwarf::Form Form) const {
@@ -388,9 +414,9 @@
       AP->EmitLabelPlusOffset(CU->getSectionSym(), Addr,
                               DIEEntry::getRefAddrSize(AP));
     else
-      AP->EmitLabelOffsetDifference(CU->getSectionSym(), Addr,
-                                    CU->getSectionSym(),
-                                    DIEEntry::getRefAddrSize(AP));
+      emitLabelOffsetDifference(AP->OutStreamer, CU->getSectionSym(), Addr,
+                                CU->getSectionSym(),
+                                DIEEntry::getRefAddrSize(AP));
   } else
     AP->EmitInt32(Entry.getOffset());
 }
diff --git a/lib/CodeGen/AsmPrinter/DIE.h b/lib/CodeGen/AsmPrinter/DIE.h
index ef05f17..e310aef 100644
--- a/lib/CodeGen/AsmPrinter/DIE.h
+++ b/lib/CodeGen/AsmPrinter/DIE.h
@@ -11,8 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_DIE_H__
-#define CODEGEN_ASMPRINTER_DIE_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DIE_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DIE_H
 
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/SmallVector.h"
@@ -381,10 +381,10 @@
 ///
 class DIEString : public DIEValue {
   const DIEValue *Access;
-  const StringRef Str;
+  StringRef Str;
 
 public:
-  DIEString(const DIEValue *Acc, const StringRef S)
+  DIEString(const DIEValue *Acc, StringRef S)
       : DIEValue(isString), Access(Acc), Str(S) {}
 
   /// getString - Grab the string out of the object.
diff --git a/lib/CodeGen/AsmPrinter/DIEHash.cpp b/lib/CodeGen/AsmPrinter/DIEHash.cpp
index c2fad59..b2a3ba8 100644
--- a/lib/CodeGen/AsmPrinter/DIEHash.cpp
+++ b/lib/CodeGen/AsmPrinter/DIEHash.cpp
@@ -261,7 +261,7 @@
     return;
   }
 
-  // otherwise, b) use the letter 'T' as a the marker, ...
+  // otherwise, b) use the letter 'T' as the marker, ...
   addULEB128('T');
 
   addULEB128(Attribute);
diff --git a/lib/CodeGen/AsmPrinter/DIEHash.h b/lib/CodeGen/AsmPrinter/DIEHash.h
index 175d660..872aa0e 100644
--- a/lib/CodeGen/AsmPrinter/DIEHash.h
+++ b/lib/CodeGen/AsmPrinter/DIEHash.h
@@ -11,8 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_DIEHASH_H__
-#define CODEGEN_ASMPRINTER_DIEHASH_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DIEHASH_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DIEHASH_H
 
 #include "DIE.h"
 #include "llvm/ADT/DenseMap.h"
diff --git a/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp b/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
index a66d08e..0c2a5e5 100644
--- a/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
+++ b/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp
@@ -8,25 +8,25 @@
 //===----------------------------------------------------------------------===//
 
 #include "DbgValueHistoryCalculator.h"
+#include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
 #include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include <algorithm>
 #include <map>
-#include <set>
+using namespace llvm;
 
 #define DEBUG_TYPE "dwarfdebug"
 
-namespace llvm {
-
 // \brief If @MI is a DBG_VALUE with debug value described by a
 // defined register, returns the number of this register.
 // In the other case, returns 0.
 static unsigned isDescribedByReg(const MachineInstr &MI) {
   assert(MI.isDebugValue());
-  assert(MI.getNumOperands() == 3);
+  assert(MI.getNumOperands() == 4);
   // If location of variable is described using a register (directly or
   // indirecltly), this register is always a first operand.
   return MI.getOperand(0).isReg() ? MI.getOperand(0).getReg() : 0;
@@ -36,7 +36,7 @@
                                          const MachineInstr &MI) {
   // Instruction range should start with a DBG_VALUE instruction for the
   // variable.
-  assert(MI.isDebugValue() && MI.getDebugVariable() == Var);
+  assert(MI.isDebugValue() && "not a DBG_VALUE");
   auto &Ranges = VarInstrRanges[Var];
   if (!Ranges.empty() && Ranges.back().second == nullptr &&
       Ranges.back().first->isIdenticalTo(&MI)) {
@@ -96,6 +96,19 @@
   VarSet.push_back(Var);
 }
 
+// \brief Terminate the location range for variables described by register at
+// @I by inserting @ClobberingInstr to their history.
+static void clobberRegisterUses(RegDescribedVarsMap &RegVars,
+                                RegDescribedVarsMap::iterator I,
+                                DbgValueHistoryMap &HistMap,
+                                const MachineInstr &ClobberingInstr) {
+  // Iterate over all variables described by this register and add this
+  // instruction to their history, clobbering it.
+  for (const auto &Var : I->second)
+    HistMap.endInstrRange(Var, ClobberingInstr);
+  RegVars.erase(I);
+}
+
 // \brief Terminate the location range for variables described by register
 // @RegNo by inserting @ClobberingInstr to their history.
 static void clobberRegisterUses(RegDescribedVarsMap &RegVars, unsigned RegNo,
@@ -104,22 +117,26 @@
   const auto &I = RegVars.find(RegNo);
   if (I == RegVars.end())
     return;
-  // Iterate over all variables described by this register and add this
-  // instruction to their history, clobbering it.
-  for (const auto &Var : I->second)
-    HistMap.endInstrRange(Var, ClobberingInstr);
-  RegVars.erase(I);
+  clobberRegisterUses(RegVars, I, HistMap, ClobberingInstr);
 }
 
-// \brief Collect all registers clobbered by @MI and insert them to @Regs.
-static void collectClobberedRegisters(const MachineInstr &MI,
+// \brief Collect all registers clobbered by @MI and apply the functor
+// @Func to their RegNo.
+// @Func should be a functor with a void(unsigned) signature. We're
+// not using std::function here for performance reasons. It has a
+// small but measurable impact. By using a functor instead of a
+// std::set& here, we can avoid the overhead of constructing
+// temporaries in calculateDbgValueHistory, which has a significant
+// performance impact.
+template<typename Callable>
+static void applyToClobberedRegisters(const MachineInstr &MI,
                                       const TargetRegisterInfo *TRI,
-                                      std::set<unsigned> &Regs) {
+                                      Callable Func) {
   for (const MachineOperand &MO : MI.operands()) {
     if (!MO.isReg() || !MO.isDef() || !MO.getReg())
       continue;
     for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid(); ++AI)
-      Regs.insert(*AI);
+      Func(*AI);
   }
 }
 
@@ -133,11 +150,12 @@
   // as the return instruction.
   DebugLoc LastLoc = LastMI->getDebugLoc();
   auto Res = LastMI;
-  for (MachineBasicBlock::const_reverse_iterator I(std::next(LastMI)); I != MBB.rend();
-       ++I) {
+  for (MachineBasicBlock::const_reverse_iterator I(std::next(LastMI)),
+       E = MBB.rend();
+       I != E; ++I) {
     if (I->getDebugLoc() != LastLoc)
       return Res;
-    Res = std::prev(I.base());
+    Res = &*I;
   }
   // If all instructions have the same debug location, assume whole MBB is
   // an epilogue.
@@ -145,25 +163,26 @@
 }
 
 // \brief Collect registers that are modified in the function body (their
-// contents is changed only in the prologue and epilogue).
+// contents is changed outside of the prologue and epilogue).
 static void collectChangingRegs(const MachineFunction *MF,
                                 const TargetRegisterInfo *TRI,
-                                std::set<unsigned> &Regs) {
+                                BitVector &Regs) {
   for (const auto &MBB : *MF) {
     auto FirstEpilogueInst = getFirstEpilogueInst(MBB);
-    bool IsInEpilogue = false;
+
     for (const auto &MI : MBB) {
-      IsInEpilogue |= &MI == FirstEpilogueInst;
-      if (!MI.getFlag(MachineInstr::FrameSetup) && !IsInEpilogue)
-        collectClobberedRegisters(MI, TRI, Regs);
+      if (&MI == FirstEpilogueInst)
+        break;
+      if (!MI.getFlag(MachineInstr::FrameSetup))
+        applyToClobberedRegisters(MI, TRI, [&](unsigned r) { Regs.set(r); });
     }
   }
 }
 
-void calculateDbgValueHistory(const MachineFunction *MF,
-                              const TargetRegisterInfo *TRI,
-                              DbgValueHistoryMap &Result) {
-  std::set<unsigned> ChangingRegs;
+void llvm::calculateDbgValueHistory(const MachineFunction *MF,
+                                    const TargetRegisterInfo *TRI,
+                                    DbgValueHistoryMap &Result) {
+  BitVector ChangingRegs(TRI->getNumRegs());
   collectChangingRegs(MF, TRI, ChangingRegs);
 
   RegDescribedVarsMap RegVars;
@@ -172,17 +191,18 @@
       if (!MI.isDebugValue()) {
         // Not a DBG_VALUE instruction. It may clobber registers which describe
         // some variables.
-        std::set<unsigned> MIClobberedRegs;
-        collectClobberedRegisters(MI, TRI, MIClobberedRegs);
-        for (unsigned RegNo : MIClobberedRegs) {
-          if (ChangingRegs.count(RegNo))
+        applyToClobberedRegisters(MI, TRI, [&](unsigned RegNo) {
+          if (ChangingRegs.test(RegNo))
             clobberRegisterUses(RegVars, RegNo, Result, MI);
-        }
+        });
         continue;
       }
 
       assert(MI.getNumOperands() > 1 && "Invalid DBG_VALUE instruction!");
-      const MDNode *Var = MI.getDebugVariable();
+      // Use the base variable (without any DW_OP_piece expressions)
+      // as index into History. The full variables including the
+      // piece expressions are attached to the MI.
+      DIVariable Var = MI.getDebugVariable();
 
       if (unsigned PrevReg = Result.getRegisterForVar(Var))
         dropRegDescribedVar(RegVars, PrevReg, Var);
@@ -196,11 +216,12 @@
     // Make sure locations for register-described variables are valid only
     // until the end of the basic block (unless it's the last basic block, in
     // which case let their liveness run off to the end of the function).
-    if (!MBB.empty() &&  &MBB != &MF->back()) {
-      for (unsigned RegNo : ChangingRegs)
-        clobberRegisterUses(RegVars, RegNo, Result, MBB.back());
+    if (!MBB.empty() && &MBB != &MF->back()) {
+      for (auto I = RegVars.begin(), E = RegVars.end(); I != E;) {
+        auto CurElem = I++; // CurElem can be erased below.
+        if (ChangingRegs.test(CurElem->first))
+          clobberRegisterUses(RegVars, CurElem, Result, MBB.back());
+      }
     }
   }
 }
-
-}
diff --git a/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h b/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h
index b9177f0..4b62007 100644
--- a/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h
+++ b/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h
@@ -7,8 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_DBGVALUEHISTORYCALCULATOR_H_
-#define CODEGEN_ASMPRINTER_DBGVALUEHISTORYCALCULATOR_H_
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DBGVALUEHISTORYCALCULATOR_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DBGVALUEHISTORYCALCULATOR_H
 
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/SmallVector.h"
@@ -28,9 +28,11 @@
   // range. If end is not specified, location is valid until the start
   // instruction of the next instruction range, or until the end of the
   // function.
+public:
   typedef std::pair<const MachineInstr *, const MachineInstr *> InstrRange;
   typedef SmallVector<InstrRange, 4> InstrRanges;
   typedef MapVector<const MDNode *, InstrRanges> InstrRangesMap;
+private:
   InstrRangesMap VarInstrRanges;
 
 public:
diff --git a/lib/CodeGen/AsmPrinter/DebugLocEntry.h b/lib/CodeGen/AsmPrinter/DebugLocEntry.h
index 3beb799..6cca985 100644
--- a/lib/CodeGen/AsmPrinter/DebugLocEntry.h
+++ b/lib/CodeGen/AsmPrinter/DebugLocEntry.h
@@ -7,14 +7,14 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H__
-#define CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H
 #include "llvm/IR/Constants.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/MC/MachineLocation.h"
 #include "llvm/MC/MCSymbol.h"
 
 namespace llvm {
-class DwarfCompileUnit;
 class MDNode;
 /// \brief This struct describes location entries emitted in the .debug_loc
 /// section.
@@ -26,25 +26,30 @@
 public:
   /// A single location or constant.
   struct Value {
-    Value(const MDNode *Var, int64_t i)
-      : Variable(Var), EntryKind(E_Integer) {
+    Value(const MDNode *Var, const MDNode *Expr, int64_t i)
+        : Variable(Var), Expression(Expr), EntryKind(E_Integer) {
       Constant.Int = i;
     }
-    Value(const MDNode *Var, const ConstantFP *CFP)
-      : Variable(Var), EntryKind(E_ConstantFP) {
+    Value(const MDNode *Var, const MDNode *Expr, const ConstantFP *CFP)
+        : Variable(Var), Expression(Expr), EntryKind(E_ConstantFP) {
       Constant.CFP = CFP;
     }
-    Value(const MDNode *Var, const ConstantInt *CIP)
-      : Variable(Var), EntryKind(E_ConstantInt) {
+    Value(const MDNode *Var, const MDNode *Expr, const ConstantInt *CIP)
+        : Variable(Var), Expression(Expr), EntryKind(E_ConstantInt) {
       Constant.CIP = CIP;
     }
-    Value(const MDNode *Var, MachineLocation Loc)
-      : Variable(Var), EntryKind(E_Location), Loc(Loc) {
+    Value(const MDNode *Var, const MDNode *Expr, MachineLocation Loc)
+        : Variable(Var), Expression(Expr), EntryKind(E_Location), Loc(Loc) {
+      assert(DIVariable(Var).Verify());
+      assert(DIExpression(Expr).Verify());
     }
 
     // The variable to which this location entry corresponds.
     const MDNode *Variable;
 
+    // Any complex address location expression for this Value.
+    const MDNode *Expression;
+
     // Type of entry that this represents.
     enum EntryType { E_Location, E_Integer, E_ConstantFP, E_ConstantInt };
     enum EntryType EntryKind;
@@ -59,23 +64,6 @@
     // Or a location in the machine frame.
     MachineLocation Loc;
 
-    bool operator==(const Value &other) const {
-      if (EntryKind != other.EntryKind)
-        return false;
-
-      switch (EntryKind) {
-      case E_Location:
-        return Loc == other.Loc;
-      case E_Integer:
-        return Constant.Int == other.Constant.Int;
-      case E_ConstantFP:
-        return Constant.CFP == other.Constant.CFP;
-      case E_ConstantInt:
-        return Constant.CIP == other.Constant.CIP;
-      }
-      llvm_unreachable("unhandled EntryKind");
-    }
-
     bool isLocation() const { return EntryKind == E_Location; }
     bool isInt() const { return EntryKind == E_Integer; }
     bool isConstantFP() const { return EntryKind == E_ConstantFP; }
@@ -84,40 +72,114 @@
     const ConstantFP *getConstantFP() const { return Constant.CFP; }
     const ConstantInt *getConstantInt() const { return Constant.CIP; }
     MachineLocation getLoc() const { return Loc; }
-    const MDNode *getVariable() const { return Variable; }
+    const MDNode *getVariableNode() const { return Variable; }
+    DIVariable getVariable() const { return DIVariable(Variable); }
+    bool isVariablePiece() const { return getExpression().isVariablePiece(); }
+    DIExpression getExpression() const { return DIExpression(Expression); }
+    friend bool operator==(const Value &, const Value &);
+    friend bool operator<(const Value &, const Value &);
   };
+
 private:
-  /// A list of locations/constants belonging to this entry.
+  /// A nonempty list of locations/constants belonging to this entry,
+  /// sorted by offset.
   SmallVector<Value, 1> Values;
 
-  /// The compile unit that this location entry is referenced by.
-  const DwarfCompileUnit *Unit;
-
 public:
-  DebugLocEntry() : Begin(nullptr), End(nullptr), Unit(nullptr) {}
-  DebugLocEntry(const MCSymbol *B, const MCSymbol *E,
-                Value Val, const DwarfCompileUnit *U)
-      : Begin(B), End(E), Unit(U) {
+  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, Value Val)
+      : Begin(B), End(E) {
     Values.push_back(std::move(Val));
   }
 
+  /// \brief If this and Next are describing different pieces of the same
+  // variable, merge them by appending Next's values to the current
+  // list of values.
+  // Return true if the merge was successful.
+  bool MergeValues(const DebugLocEntry &Next) {
+    if (Begin == Next.Begin) {
+      DIExpression Expr(Values[0].Expression);
+      DIVariable Var(Values[0].Variable);
+      DIExpression NextExpr(Next.Values[0].Expression);
+      DIVariable NextVar(Next.Values[0].Variable);
+      if (Var == NextVar && Expr.isVariablePiece() &&
+          NextExpr.isVariablePiece()) {
+        addValues(Next.Values);
+        End = Next.End;
+        return true;
+      }
+    }
+    return false;
+  }
+
   /// \brief Attempt to merge this DebugLocEntry with Next and return
   /// true if the merge was successful. Entries can be merged if they
   /// share the same Loc/Constant and if Next immediately follows this
   /// Entry.
-  bool Merge(const DebugLocEntry &Next) {
+  bool MergeRanges(const DebugLocEntry &Next) {
+    // If this and Next are describing the same variable, merge them.
     if ((End == Next.Begin && Values == Next.Values)) {
       End = Next.End;
       return true;
     }
     return false;
   }
+
   const MCSymbol *getBeginSym() const { return Begin; }
   const MCSymbol *getEndSym() const { return End; }
-  const DwarfCompileUnit *getCU() const { return Unit; }
-  const ArrayRef<Value> getValues() const { return Values; }
-  void addValue(Value Val) { Values.push_back(Val); }
+  ArrayRef<Value> getValues() const { return Values; }
+  void addValues(ArrayRef<DebugLocEntry::Value> Vals) {
+    Values.append(Vals.begin(), Vals.end());
+    sortUniqueValues();
+    assert(std::all_of(Values.begin(), Values.end(), [](DebugLocEntry::Value V){
+          return V.isVariablePiece();
+        }) && "value must be a piece");
+  }
+
+  // Sort the pieces by offset.
+  // Remove any duplicate entries by dropping all but the first.
+  void sortUniqueValues() {
+    std::sort(Values.begin(), Values.end());
+    Values.erase(std::unique(Values.begin(), Values.end(),
+                             [](const Value &A, const Value &B) {
+                   return A.getVariable() == B.getVariable() &&
+                          A.getExpression() == B.getExpression();
+                 }),
+                 Values.end());
+  }
 };
 
+/// Compare two Values for equality.
+inline bool operator==(const DebugLocEntry::Value &A,
+                       const DebugLocEntry::Value &B) {
+  if (A.EntryKind != B.EntryKind)
+    return false;
+
+  if (A.Expression != B.Expression)
+    return false;
+
+  if (A.Variable != B.Variable)
+    return false;
+
+  switch (A.EntryKind) {
+  case DebugLocEntry::Value::E_Location:
+    return A.Loc == B.Loc;
+  case DebugLocEntry::Value::E_Integer:
+    return A.Constant.Int == B.Constant.Int;
+  case DebugLocEntry::Value::E_ConstantFP:
+    return A.Constant.CFP == B.Constant.CFP;
+  case DebugLocEntry::Value::E_ConstantInt:
+    return A.Constant.CIP == B.Constant.CIP;
+  }
+  llvm_unreachable("unhandled EntryKind");
 }
+
+/// Compare two pieces based on their offset.
+inline bool operator<(const DebugLocEntry::Value &A,
+                      const DebugLocEntry::Value &B) {
+  return A.getExpression().getPieceOffset() <
+         B.getExpression().getPieceOffset();
+}
+
+}
+
 #endif
diff --git a/lib/CodeGen/AsmPrinter/DebugLocList.h b/lib/CodeGen/AsmPrinter/DebugLocList.h
index 7a51c7b..2a4f58f 100644
--- a/lib/CodeGen/AsmPrinter/DebugLocList.h
+++ b/lib/CodeGen/AsmPrinter/DebugLocList.h
@@ -7,16 +7,18 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_DEBUGLOCLIST_H__
-#define CODEGEN_ASMPRINTER_DEBUGLOCLIST_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCLIST_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCLIST_H
 
-#include "llvm/MC/MCSymbol.h"
 #include "llvm/ADT/SmallVector.h"
 #include "DebugLocEntry.h"
 
 namespace llvm {
+class DwarfCompileUnit;
+class MCSymbol;
 struct DebugLocList {
   MCSymbol *Label;
+  DwarfCompileUnit *CU;
   SmallVector<DebugLocEntry, 4> List;
 };
 }
diff --git a/lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp b/lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp
index e9527c4..7e87566 100644
--- a/lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp
@@ -13,6 +13,7 @@
 
 #include "DwarfAccelTable.h"
 #include "DIE.h"
+#include "DwarfCompileUnit.h"
 #include "DwarfDebug.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Twine.h"
@@ -174,7 +175,8 @@
 // Walk through the buckets and emit the full data for each element in
 // the bucket. For the string case emit the dies and the various offsets.
 // Terminate each HashData bucket with 0.
-void DwarfAccelTable::EmitData(AsmPrinter *Asm, DwarfFile *D) {
+void DwarfAccelTable::EmitData(AsmPrinter *Asm, DwarfDebug *D,
+                               MCSymbol *StrSym) {
   uint64_t PrevHash = UINT64_MAX;
   for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
     for (HashList::const_iterator HI = Buckets[i].begin(),
@@ -183,13 +185,14 @@
       // Remember to emit the label for our offset.
       Asm->OutStreamer.EmitLabel((*HI)->Sym);
       Asm->OutStreamer.AddComment((*HI)->Str);
-      Asm->EmitSectionOffset((*HI)->Data.StrSym,
-                             D->getStringPool().getSectionSymbol());
+      Asm->EmitSectionOffset((*HI)->Data.StrSym, StrSym);
       Asm->OutStreamer.AddComment("Num DIEs");
       Asm->EmitInt32((*HI)->Data.Values.size());
       for (HashDataContents *HD : (*HI)->Data.Values) {
         // Emit the DIE offset
-        Asm->EmitInt32(HD->Die->getOffset());
+        DwarfCompileUnit *CU = D->lookupUnit(HD->Die->getUnit());
+        assert(CU && "Accelerated DIE should belong to a CU.");
+        Asm->EmitInt32(HD->Die->getOffset() + CU->getDebugInfoOffset());
         // If we have multiple Atoms emit that info too.
         // FIXME: A bit of a hack, we either emit only one atom or all info.
         if (HeaderData.Atoms.size() > 1) {
@@ -206,7 +209,8 @@
 }
 
 // Emit the entire data structure to the output file.
-void DwarfAccelTable::Emit(AsmPrinter *Asm, MCSymbol *SecBegin, DwarfFile *D) {
+void DwarfAccelTable::Emit(AsmPrinter *Asm, MCSymbol *SecBegin, DwarfDebug *D,
+                           MCSymbol *StrSym) {
   // Emit the header.
   EmitHeader(Asm);
 
@@ -220,7 +224,7 @@
   EmitOffsets(Asm, SecBegin);
 
   // Emit the hash data.
-  EmitData(Asm, D);
+  EmitData(Asm, D, StrSym);
 }
 
 #ifndef NDEBUG
diff --git a/lib/CodeGen/AsmPrinter/DwarfAccelTable.h b/lib/CodeGen/AsmPrinter/DwarfAccelTable.h
index a3cc95f..3cdf678 100644
--- a/lib/CodeGen/AsmPrinter/DwarfAccelTable.h
+++ b/lib/CodeGen/AsmPrinter/DwarfAccelTable.h
@@ -11,8 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_DWARFACCELTABLE_H__
-#define CODEGEN_ASMPRINTER_DWARFACCELTABLE_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFACCELTABLE_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFACCELTABLE_H
 
 #include "DIE.h"
 #include "llvm/ADT/ArrayRef.h"
@@ -62,7 +62,7 @@
 namespace llvm {
 
 class AsmPrinter;
-class DwarfFile;
+class DwarfDebug;
 
 class DwarfAccelTable {
 
@@ -140,7 +140,7 @@
 private:
   struct TableHeaderData {
     uint32_t die_offset_base;
-    SmallVector<Atom, 1> Atoms;
+    SmallVector<Atom, 3> Atoms;
 
     TableHeaderData(ArrayRef<Atom> AtomList, uint32_t offset = 0)
         : die_offset_base(offset), Atoms(AtomList.begin(), AtomList.end()) {}
@@ -223,7 +223,7 @@
   void EmitBuckets(AsmPrinter *);
   void EmitHashes(AsmPrinter *);
   void EmitOffsets(AsmPrinter *, MCSymbol *);
-  void EmitData(AsmPrinter *, DwarfFile *D);
+  void EmitData(AsmPrinter *, DwarfDebug *D, MCSymbol *StrSym);
 
   // Allocator for HashData and HashDataContents.
   BumpPtrAllocator Allocator;
@@ -248,7 +248,7 @@
   void AddName(StringRef Name, MCSymbol *StrSym, const DIE *Die,
                char Flags = 0);
   void FinalizeTable(AsmPrinter *, StringRef);
-  void Emit(AsmPrinter *, MCSymbol *, DwarfFile *);
+  void Emit(AsmPrinter *, MCSymbol *, DwarfDebug *, MCSymbol *StrSym);
 #ifndef NDEBUG
   void print(raw_ostream &O);
   void dump() { print(dbgs()); }
diff --git a/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp b/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
index 74215aa..0dc52da 100644
--- a/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
@@ -51,7 +51,7 @@
   if (moveTypeModule == AsmPrinter::CFI_M_Debug)
     Asm->OutStreamer.EmitCFISections(false, true);
 
-  if (!Asm->MAI->isExceptionHandlingDwarf())
+  if (!Asm->MAI->usesItaniumLSDAForExceptions())
     return;
 
   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
new file mode 100644
index 0000000..2f1b0e5
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -0,0 +1,862 @@
+#include "DwarfCompileUnit.h"
+
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/GlobalValue.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/Target/TargetFrameLowering.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+
+namespace llvm {
+
+DwarfCompileUnit::DwarfCompileUnit(unsigned UID, DICompileUnit Node,
+                                   AsmPrinter *A, DwarfDebug *DW,
+                                   DwarfFile *DWU)
+    : DwarfUnit(UID, dwarf::DW_TAG_compile_unit, Node, A, DW, DWU),
+      Skeleton(nullptr), LabelBegin(nullptr), BaseAddress(nullptr) {
+  insertDIE(Node, &getUnitDie());
+}
+
+/// addLabelAddress - Add a dwarf label attribute data and value using
+/// DW_FORM_addr or DW_FORM_GNU_addr_index.
+///
+void DwarfCompileUnit::addLabelAddress(DIE &Die, dwarf::Attribute Attribute,
+                                       const MCSymbol *Label) {
+
+  // Don't use the address pool in non-fission or in the skeleton unit itself.
+  // FIXME: Once GDB supports this, it's probably worthwhile using the address
+  // pool from the skeleton - maybe even in non-fission (possibly fewer
+  // relocations by sharing them in the pool, but we have other ideas about how
+  // to reduce the number of relocations as well/instead).
+  if (!DD->useSplitDwarf() || !Skeleton)
+    return addLocalLabelAddress(Die, Attribute, Label);
+
+  if (Label)
+    DD->addArangeLabel(SymbolCU(this, Label));
+
+  unsigned idx = DD->getAddressPool().getIndex(Label);
+  DIEValue *Value = new (DIEValueAllocator) DIEInteger(idx);
+  Die.addValue(Attribute, dwarf::DW_FORM_GNU_addr_index, Value);
+}
+
+void DwarfCompileUnit::addLocalLabelAddress(DIE &Die,
+                                            dwarf::Attribute Attribute,
+                                            const MCSymbol *Label) {
+  if (Label)
+    DD->addArangeLabel(SymbolCU(this, Label));
+
+  Die.addValue(Attribute, dwarf::DW_FORM_addr,
+               Label ? (DIEValue *)new (DIEValueAllocator) DIELabel(Label)
+                     : new (DIEValueAllocator) DIEInteger(0));
+}
+
+unsigned DwarfCompileUnit::getOrCreateSourceID(StringRef FileName,
+                                               StringRef DirName) {
+  // If we print assembly, we can't separate .file entries according to
+  // compile units. Thus all files will belong to the default compile unit.
+
+  // FIXME: add a better feature test than hasRawTextSupport. Even better,
+  // extend .file to support this.
+  return Asm->OutStreamer.EmitDwarfFileDirective(
+      0, DirName, FileName,
+      Asm->OutStreamer.hasRawTextSupport() ? 0 : getUniqueID());
+}
+
+// Return const expression if value is a GEP to access merged global
+// constant. e.g.
+// i8* getelementptr ({ i8, i8, i8, i8 }* @_MergedGlobals, i32 0, i32 0)
+static const ConstantExpr *getMergedGlobalExpr(const Value *V) {
+  const ConstantExpr *CE = dyn_cast_or_null<ConstantExpr>(V);
+  if (!CE || CE->getNumOperands() != 3 ||
+      CE->getOpcode() != Instruction::GetElementPtr)
+    return nullptr;
+
+  // First operand points to a global struct.
+  Value *Ptr = CE->getOperand(0);
+  if (!isa<GlobalValue>(Ptr) ||
+      !isa<StructType>(cast<PointerType>(Ptr->getType())->getElementType()))
+    return nullptr;
+
+  // Second operand is zero.
+  const ConstantInt *CI = dyn_cast_or_null<ConstantInt>(CE->getOperand(1));
+  if (!CI || !CI->isZero())
+    return nullptr;
+
+  // Third operand is offset.
+  if (!isa<ConstantInt>(CE->getOperand(2)))
+    return nullptr;
+
+  return CE;
+}
+
+/// getOrCreateGlobalVariableDIE - get or create global variable DIE.
+DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(DIGlobalVariable GV) {
+  // Check for pre-existence.
+  if (DIE *Die = getDIE(GV))
+    return Die;
+
+  assert(GV.isGlobalVariable());
+
+  DIScope GVContext = DD->resolve(GV.getContext());
+  DIType GTy = DD->resolve(GV.getType());
+
+  // Construct the context before querying for the existence of the DIE in
+  // case such construction creates the DIE.
+  DIE *ContextDIE = getOrCreateContextDIE(GVContext);
+
+  // Add to map.
+  DIE *VariableDIE = &createAndAddDIE(GV.getTag(), *ContextDIE, GV);
+  DIScope DeclContext;
+
+  if (DIDerivedType SDMDecl = GV.getStaticDataMemberDeclaration()) {
+    DeclContext = resolve(SDMDecl.getContext());
+    assert(SDMDecl.isStaticMember() && "Expected static member decl");
+    assert(GV.isDefinition());
+    // We need the declaration DIE that is in the static member's class.
+    DIE *VariableSpecDIE = getOrCreateStaticMemberDIE(SDMDecl);
+    addDIEEntry(*VariableDIE, dwarf::DW_AT_specification, *VariableSpecDIE);
+  } else {
+    DeclContext = resolve(GV.getContext());
+    // Add name and type.
+    addString(*VariableDIE, dwarf::DW_AT_name, GV.getDisplayName());
+    addType(*VariableDIE, GTy);
+
+    // Add scoping info.
+    if (!GV.isLocalToUnit())
+      addFlag(*VariableDIE, dwarf::DW_AT_external);
+
+    // Add line number info.
+    addSourceLine(*VariableDIE, GV);
+  }
+
+  if (!GV.isDefinition())
+    addFlag(*VariableDIE, dwarf::DW_AT_declaration);
+
+  // Add location.
+  bool addToAccelTable = false;
+  bool isGlobalVariable = GV.getGlobal() != nullptr;
+  if (isGlobalVariable) {
+    addToAccelTable = true;
+    DIELoc *Loc = new (DIEValueAllocator) DIELoc();
+    const MCSymbol *Sym = Asm->getSymbol(GV.getGlobal());
+    if (GV.getGlobal()->isThreadLocal()) {
+      // FIXME: Make this work with -gsplit-dwarf.
+      unsigned PointerSize = Asm->getDataLayout().getPointerSize();
+      assert((PointerSize == 4 || PointerSize == 8) &&
+             "Add support for other sizes if necessary");
+      // Based on GCC's support for TLS:
+      if (!DD->useSplitDwarf()) {
+        // 1) Start with a constNu of the appropriate pointer size
+        addUInt(*Loc, dwarf::DW_FORM_data1,
+                PointerSize == 4 ? dwarf::DW_OP_const4u : dwarf::DW_OP_const8u);
+        // 2) containing the (relocated) offset of the TLS variable
+        //    within the module's TLS block.
+        addExpr(*Loc, dwarf::DW_FORM_udata,
+                Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym));
+      } else {
+        addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_const_index);
+        addUInt(*Loc, dwarf::DW_FORM_udata,
+                DD->getAddressPool().getIndex(Sym, /* TLS */ true));
+      }
+      // 3) followed by a custom OP to make the debugger do a TLS lookup.
+      addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_push_tls_address);
+    } else {
+      DD->addArangeLabel(SymbolCU(this, Sym));
+      addOpAddress(*Loc, Sym);
+    }
+
+    addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
+    // Add the linkage name.
+    StringRef LinkageName = GV.getLinkageName();
+    if (!LinkageName.empty())
+      // From DWARF4: DIEs to which DW_AT_linkage_name may apply include:
+      // TAG_common_block, TAG_constant, TAG_entry_point, TAG_subprogram and
+      // TAG_variable.
+      addString(*VariableDIE,
+                DD->getDwarfVersion() >= 4 ? dwarf::DW_AT_linkage_name
+                                           : dwarf::DW_AT_MIPS_linkage_name,
+                GlobalValue::getRealLinkageName(LinkageName));
+  } else if (const ConstantInt *CI =
+                 dyn_cast_or_null<ConstantInt>(GV.getConstant())) {
+    addConstantValue(*VariableDIE, CI, GTy);
+  } else if (const ConstantExpr *CE = getMergedGlobalExpr(GV.getConstant())) {
+    addToAccelTable = true;
+    // GV is a merged global.
+    DIELoc *Loc = new (DIEValueAllocator) DIELoc();
+    Value *Ptr = CE->getOperand(0);
+    MCSymbol *Sym = Asm->getSymbol(cast<GlobalValue>(Ptr));
+    DD->addArangeLabel(SymbolCU(this, Sym));
+    addOpAddress(*Loc, Sym);
+    addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
+    SmallVector<Value *, 3> Idx(CE->op_begin() + 1, CE->op_end());
+    addUInt(*Loc, dwarf::DW_FORM_udata,
+            Asm->getDataLayout().getIndexedOffset(Ptr->getType(), Idx));
+    addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_plus);
+    addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
+  }
+
+  if (addToAccelTable) {
+    DD->addAccelName(GV.getName(), *VariableDIE);
+
+    // If the linkage name is different than the name, go ahead and output
+    // that as well into the name table.
+    if (GV.getLinkageName() != "" && GV.getName() != GV.getLinkageName())
+      DD->addAccelName(GV.getLinkageName(), *VariableDIE);
+  }
+
+  addGlobalName(GV.getName(), *VariableDIE, DeclContext);
+  return VariableDIE;
+}
+
+void DwarfCompileUnit::addRange(RangeSpan Range) {
+  bool SameAsPrevCU = this == DD->getPrevCU();
+  DD->setPrevCU(this);
+  // If we have no current ranges just add the range and return, otherwise,
+  // check the current section and CU against the previous section and CU we
+  // emitted into and the subprogram was contained within. If these are the
+  // same then extend our current range, otherwise add this as a new range.
+  if (CURanges.empty() || !SameAsPrevCU ||
+      (&CURanges.back().getEnd()->getSection() !=
+       &Range.getEnd()->getSection())) {
+    CURanges.push_back(Range);
+    return;
+  }
+
+  CURanges.back().setEnd(Range.getEnd());
+}
+
+void DwarfCompileUnit::addSectionLabel(DIE &Die, dwarf::Attribute Attribute,
+                                       const MCSymbol *Label,
+                                       const MCSymbol *Sec) {
+  if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+    addLabel(Die, Attribute,
+             DD->getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
+                                        : dwarf::DW_FORM_data4,
+             Label);
+  else
+    addSectionDelta(Die, Attribute, Label, Sec);
+}
+
+void DwarfCompileUnit::initStmtList(MCSymbol *DwarfLineSectionSym) {
+  // Define start line table label for each Compile Unit.
+  MCSymbol *LineTableStartSym =
+      Asm->OutStreamer.getDwarfLineTableSymbol(getUniqueID());
+
+  stmtListIndex = UnitDie.getValues().size();
+
+  // 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.
+  addSectionLabel(UnitDie, dwarf::DW_AT_stmt_list, LineTableStartSym,
+                  DwarfLineSectionSym);
+}
+
+void DwarfCompileUnit::applyStmtList(DIE &D) {
+  D.addValue(dwarf::DW_AT_stmt_list,
+             UnitDie.getAbbrev().getData()[stmtListIndex].getForm(),
+             UnitDie.getValues()[stmtListIndex]);
+}
+
+void DwarfCompileUnit::attachLowHighPC(DIE &D, const MCSymbol *Begin,
+                                       const MCSymbol *End) {
+  assert(Begin && "Begin label should not be null!");
+  assert(End && "End label should not be null!");
+  assert(Begin->isDefined() && "Invalid starting label");
+  assert(End->isDefined() && "Invalid end label");
+
+  addLabelAddress(D, dwarf::DW_AT_low_pc, Begin);
+  if (DD->getDwarfVersion() < 4)
+    addLabelAddress(D, dwarf::DW_AT_high_pc, End);
+  else
+    addLabelDelta(D, dwarf::DW_AT_high_pc, End, Begin);
+}
+
+// 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 &DwarfCompileUnit::updateSubprogramScopeDIE(DISubprogram SP) {
+  DIE *SPDie = getOrCreateSubprogramDIE(SP, includeMinimalInlineScopes());
+
+  attachLowHighPC(*SPDie, DD->getFunctionBeginSym(), DD->getFunctionEndSym());
+  if (!DD->getCurrentFunction()->getTarget().Options.DisableFramePointerElim(
+          *DD->getCurrentFunction()))
+    addFlag(*SPDie, dwarf::DW_AT_APPLE_omit_frame_ptr);
+
+  // Only include DW_AT_frame_base in full debug info
+  if (!includeMinimalInlineScopes()) {
+    const TargetRegisterInfo *RI =
+        Asm->TM.getSubtargetImpl()->getRegisterInfo();
+    MachineLocation Location(RI->getFrameRegister(*Asm->MF));
+    addAddress(*SPDie, dwarf::DW_AT_frame_base, Location);
+  }
+
+  // Add name to the name table, we do this here because we're guaranteed
+  // to have concrete versions of our DW_TAG_subprogram nodes.
+  DD->addSubprogramNames(SP, *SPDie);
+
+  return *SPDie;
+}
+
+// Construct a DIE for this scope.
+void DwarfCompileUnit::constructScopeDIE(
+    LexicalScope *Scope, SmallVectorImpl<std::unique_ptr<DIE>> &FinalChildren) {
+  if (!Scope || !Scope->getScopeNode())
+    return;
+
+  DIScope DS(Scope->getScopeNode());
+
+  assert((Scope->getInlinedAt() || !DS.isSubprogram()) &&
+         "Only handle inlined subprograms here, use "
+         "constructSubprogramScopeDIE for non-inlined "
+         "subprograms");
+
+  SmallVector<std::unique_ptr<DIE>, 8> Children;
+
+  // 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.
+  std::unique_ptr<DIE> ScopeDIE;
+  if (Scope->getParent() && DS.isSubprogram()) {
+    ScopeDIE = constructInlinedScopeDIE(Scope);
+    if (!ScopeDIE)
+      return;
+    // We create children when the scope DIE is not null.
+    createScopeChildrenDIE(Scope, Children);
+  } else {
+    // Early exit when we know the scope DIE is going to be null.
+    if (DD->isLexicalScopeDIENull(Scope))
+      return;
+
+    unsigned ChildScopeCount;
+
+    // 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.
+    createScopeChildrenDIE(Scope, Children, &ChildScopeCount);
+
+    // Skip imported directives in gmlt-like data.
+    if (!includeMinimalInlineScopes()) {
+      // There is no need to emit empty lexical block DIE.
+      for (const auto &E : DD->findImportedEntitiesForScope(DS))
+        Children.push_back(
+            constructImportedEntityDIE(DIImportedEntity(E.second)));
+    }
+
+    // If there are only other scopes as children, put them directly in the
+    // parent instead, as this scope would serve no purpose.
+    if (Children.size() == ChildScopeCount) {
+      FinalChildren.insert(FinalChildren.end(),
+                           std::make_move_iterator(Children.begin()),
+                           std::make_move_iterator(Children.end()));
+      return;
+    }
+    ScopeDIE = constructLexicalScopeDIE(Scope);
+    assert(ScopeDIE && "Scope DIE should not be null.");
+  }
+
+  // Add children
+  for (auto &I : Children)
+    ScopeDIE->addChild(std::move(I));
+
+  FinalChildren.push_back(std::move(ScopeDIE));
+}
+
+void DwarfCompileUnit::addSectionDelta(DIE &Die, dwarf::Attribute Attribute,
+                                       const MCSymbol *Hi, const MCSymbol *Lo) {
+  DIEValue *Value = new (DIEValueAllocator) DIEDelta(Hi, Lo);
+  Die.addValue(Attribute, DD->getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
+                                                     : dwarf::DW_FORM_data4,
+               Value);
+}
+
+void DwarfCompileUnit::addScopeRangeList(DIE &ScopeDIE,
+                                         SmallVector<RangeSpan, 2> Range) {
+  // Emit offset in .debug_range as a relocatable label. emitDIE will handle
+  // emitting it appropriately.
+  auto *RangeSectionSym = DD->getRangeSectionSym();
+
+  RangeSpanList List(
+      Asm->GetTempSymbol("debug_ranges", DD->getNextRangeNumber()),
+      std::move(Range));
+
+  // Under fission, ranges are specified by constant offsets relative to the
+  // CU's DW_AT_GNU_ranges_base.
+  if (isDwoUnit())
+    addSectionDelta(ScopeDIE, dwarf::DW_AT_ranges, List.getSym(),
+                    RangeSectionSym);
+  else
+    addSectionLabel(ScopeDIE, dwarf::DW_AT_ranges, List.getSym(),
+                    RangeSectionSym);
+
+  // Add the range list to the set of ranges to be emitted.
+  (Skeleton ? Skeleton : this)->CURangeLists.push_back(std::move(List));
+}
+
+void DwarfCompileUnit::attachRangesOrLowHighPC(
+    DIE &Die, SmallVector<RangeSpan, 2> Ranges) {
+  if (Ranges.size() == 1) {
+    const auto &single = Ranges.front();
+    attachLowHighPC(Die, single.getStart(), single.getEnd());
+  } else
+    addScopeRangeList(Die, std::move(Ranges));
+}
+
+void DwarfCompileUnit::attachRangesOrLowHighPC(
+    DIE &Die, const SmallVectorImpl<InsnRange> &Ranges) {
+  SmallVector<RangeSpan, 2> List;
+  List.reserve(Ranges.size());
+  for (const InsnRange &R : Ranges)
+    List.push_back(RangeSpan(DD->getLabelBeforeInsn(R.first),
+                             DD->getLabelAfterInsn(R.second)));
+  attachRangesOrLowHighPC(Die, std::move(List));
+}
+
+// This scope represents inlined body of a function. Construct DIE to
+// represent this concrete inlined copy of the function.
+std::unique_ptr<DIE>
+DwarfCompileUnit::constructInlinedScopeDIE(LexicalScope *Scope) {
+  assert(Scope->getScopeNode());
+  DIScope DS(Scope->getScopeNode());
+  DISubprogram InlinedSP = getDISubprogram(DS);
+  // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
+  // was inlined from another compile unit.
+  DIE *OriginDIE = DU->getAbstractSPDies()[InlinedSP];
+  assert(OriginDIE && "Unable to find original DIE for an inlined subprogram.");
+
+  auto ScopeDIE = make_unique<DIE>(dwarf::DW_TAG_inlined_subroutine);
+  addDIEEntry(*ScopeDIE, dwarf::DW_AT_abstract_origin, *OriginDIE);
+
+  attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());
+
+  // Add the call site information to the DIE.
+  DILocation DL(Scope->getInlinedAt());
+  addUInt(*ScopeDIE, dwarf::DW_AT_call_file, None,
+          getOrCreateSourceID(DL.getFilename(), DL.getDirectory()));
+  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.
+  DD->addSubprogramNames(InlinedSP, *ScopeDIE);
+
+  return ScopeDIE;
+}
+
+// Construct new DW_TAG_lexical_block for this scope and attach
+// DW_AT_low_pc/DW_AT_high_pc labels.
+std::unique_ptr<DIE>
+DwarfCompileUnit::constructLexicalScopeDIE(LexicalScope *Scope) {
+  if (DD->isLexicalScopeDIENull(Scope))
+    return nullptr;
+
+  auto ScopeDIE = make_unique<DIE>(dwarf::DW_TAG_lexical_block);
+  if (Scope->isAbstractScope())
+    return ScopeDIE;
+
+  attachRangesOrLowHighPC(*ScopeDIE, Scope->getRanges());
+
+  return ScopeDIE;
+}
+
+/// constructVariableDIE - Construct a DIE for the given DbgVariable.
+std::unique_ptr<DIE> DwarfCompileUnit::constructVariableDIE(DbgVariable &DV,
+                                                            bool Abstract) {
+  auto D = constructVariableDIEImpl(DV, Abstract);
+  DV.setDIE(*D);
+  return D;
+}
+
+std::unique_ptr<DIE>
+DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
+                                           bool Abstract) {
+  // Define variable debug information entry.
+  auto VariableDie = make_unique<DIE>(DV.getTag());
+
+  if (Abstract) {
+    applyVariableAttributes(DV, *VariableDie);
+    return VariableDie;
+  }
+
+  // Add variable address.
+
+  unsigned Offset = DV.getDotDebugLocOffset();
+  if (Offset != ~0U) {
+    addLocationList(*VariableDie, dwarf::DW_AT_location, Offset);
+    return VariableDie;
+  }
+
+  // Check if variable is described by a DBG_VALUE instruction.
+  if (const MachineInstr *DVInsn = DV.getMInsn()) {
+    assert(DVInsn->getNumOperands() == 4);
+    if (DVInsn->getOperand(0).isReg()) {
+      const MachineOperand RegOp = DVInsn->getOperand(0);
+      // If the second operand is an immediate, this is an indirect value.
+      if (DVInsn->getOperand(1).isImm()) {
+        MachineLocation Location(RegOp.getReg(),
+                                 DVInsn->getOperand(1).getImm());
+        addVariableAddress(DV, *VariableDie, Location);
+      } else if (RegOp.getReg())
+        addVariableAddress(DV, *VariableDie, MachineLocation(RegOp.getReg()));
+    } else if (DVInsn->getOperand(0).isImm())
+      addConstantValue(*VariableDie, DVInsn->getOperand(0), DV.getType());
+    else if (DVInsn->getOperand(0).isFPImm())
+      addConstantFPValue(*VariableDie, DVInsn->getOperand(0));
+    else if (DVInsn->getOperand(0).isCImm())
+      addConstantValue(*VariableDie, DVInsn->getOperand(0).getCImm(),
+                       DV.getType());
+
+    return VariableDie;
+  }
+
+  // .. else use frame index.
+  int FI = DV.getFrameIndex();
+  if (FI != ~0) {
+    unsigned FrameReg = 0;
+    const TargetFrameLowering *TFI =
+        Asm->TM.getSubtargetImpl()->getFrameLowering();
+    int Offset = TFI->getFrameIndexReference(*Asm->MF, FI, FrameReg);
+    MachineLocation Location(FrameReg, Offset);
+    addVariableAddress(DV, *VariableDie, Location);
+  }
+
+  return VariableDie;
+}
+
+std::unique_ptr<DIE> DwarfCompileUnit::constructVariableDIE(
+    DbgVariable &DV, const LexicalScope &Scope, DIE *&ObjectPointer) {
+  auto Var = constructVariableDIE(DV, Scope.isAbstractScope());
+  if (DV.isObjectPointer())
+    ObjectPointer = Var.get();
+  return Var;
+}
+
+DIE *DwarfCompileUnit::createScopeChildrenDIE(
+    LexicalScope *Scope, SmallVectorImpl<std::unique_ptr<DIE>> &Children,
+    unsigned *ChildScopeCount) {
+  DIE *ObjectPointer = nullptr;
+
+  for (DbgVariable *DV : DU->getScopeVariables().lookup(Scope))
+    Children.push_back(constructVariableDIE(*DV, *Scope, ObjectPointer));
+
+  unsigned ChildCountWithoutScopes = Children.size();
+
+  for (LexicalScope *LS : Scope->getChildren())
+    constructScopeDIE(LS, Children);
+
+  if (ChildScopeCount)
+    *ChildScopeCount = Children.size() - ChildCountWithoutScopes;
+
+  return ObjectPointer;
+}
+
+void DwarfCompileUnit::constructSubprogramScopeDIE(LexicalScope *Scope) {
+  assert(Scope && Scope->getScopeNode());
+  assert(!Scope->getInlinedAt());
+  assert(!Scope->isAbstractScope());
+  DISubprogram Sub(Scope->getScopeNode());
+
+  assert(Sub.isSubprogram());
+
+  DD->getProcessedSPNodes().insert(Sub);
+
+  DIE &ScopeDIE = updateSubprogramScopeDIE(Sub);
+
+  // If this is a variadic function, add an unspecified parameter.
+  DITypeArray FnArgs = Sub.getType().getTypeArray();
+
+  // Collect lexical scope children first.
+  // ObjectPointer might be a local (non-argument) local variable if it's a
+  // block's synthetic this pointer.
+  if (DIE *ObjectPointer = createAndAddScopeChildren(Scope, ScopeDIE))
+    addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, *ObjectPointer);
+
+  // If we have a single element of null, it is a function that returns void.
+  // If we have more than one elements and the last one is null, it is a
+  // variadic function.
+  if (FnArgs.getNumElements() > 1 &&
+      !FnArgs.getElement(FnArgs.getNumElements() - 1) &&
+      !includeMinimalInlineScopes())
+    ScopeDIE.addChild(make_unique<DIE>(dwarf::DW_TAG_unspecified_parameters));
+}
+
+DIE *DwarfCompileUnit::createAndAddScopeChildren(LexicalScope *Scope,
+                                                 DIE &ScopeDIE) {
+  // We create children when the scope DIE is not null.
+  SmallVector<std::unique_ptr<DIE>, 8> Children;
+  DIE *ObjectPointer = createScopeChildrenDIE(Scope, Children);
+
+  // Add children
+  for (auto &I : Children)
+    ScopeDIE.addChild(std::move(I));
+
+  return ObjectPointer;
+}
+
+void
+DwarfCompileUnit::constructAbstractSubprogramScopeDIE(LexicalScope *Scope) {
+  DIE *&AbsDef = DU->getAbstractSPDies()[Scope->getScopeNode()];
+  if (AbsDef)
+    return;
+
+  DISubprogram SP(Scope->getScopeNode());
+
+  DIE *ContextDIE;
+
+  if (includeMinimalInlineScopes())
+    ContextDIE = &getUnitDie();
+  // Some of this is duplicated from DwarfUnit::getOrCreateSubprogramDIE, with
+  // the important distinction that the DIDescriptor is not associated with the
+  // DIE (since the DIDescriptor will be associated with the concrete DIE, if
+  // any). It could be refactored to some common utility function.
+  else if (DISubprogram SPDecl = SP.getFunctionDeclaration()) {
+    ContextDIE = &getUnitDie();
+    getOrCreateSubprogramDIE(SPDecl);
+  } else
+    ContextDIE = getOrCreateContextDIE(resolve(SP.getContext()));
+
+  // Passing null as the associated DIDescriptor because the abstract definition
+  // shouldn't be found by lookup.
+  AbsDef =
+      &createAndAddDIE(dwarf::DW_TAG_subprogram, *ContextDIE, DIDescriptor());
+  applySubprogramAttributesToDefinition(SP, *AbsDef);
+
+  if (!includeMinimalInlineScopes())
+    addUInt(*AbsDef, dwarf::DW_AT_inline, None, dwarf::DW_INL_inlined);
+  if (DIE *ObjectPointer = createAndAddScopeChildren(Scope, *AbsDef))
+    addDIEEntry(*AbsDef, dwarf::DW_AT_object_pointer, *ObjectPointer);
+}
+
+std::unique_ptr<DIE>
+DwarfCompileUnit::constructImportedEntityDIE(const DIImportedEntity &Module) {
+  assert(Module.Verify() &&
+         "Use one of the MDNode * overloads to handle invalid metadata");
+  std::unique_ptr<DIE> IMDie = make_unique<DIE>((dwarf::Tag)Module.getTag());
+  insertDIE(Module, IMDie.get());
+  DIE *EntityDie;
+  DIDescriptor Entity = resolve(Module.getEntity());
+  if (Entity.isNameSpace())
+    EntityDie = getOrCreateNameSpace(DINameSpace(Entity));
+  else if (Entity.isSubprogram())
+    EntityDie = getOrCreateSubprogramDIE(DISubprogram(Entity));
+  else if (Entity.isType())
+    EntityDie = getOrCreateTypeDIE(DIType(Entity));
+  else if (Entity.isGlobalVariable())
+    EntityDie = getOrCreateGlobalVariableDIE(DIGlobalVariable(Entity));
+  else
+    EntityDie = getDIE(Entity);
+  assert(EntityDie);
+  addSourceLine(*IMDie, Module.getLineNumber(),
+                Module.getContext().getFilename(),
+                Module.getContext().getDirectory());
+  addDIEEntry(*IMDie, dwarf::DW_AT_import, *EntityDie);
+  StringRef Name = Module.getName();
+  if (!Name.empty())
+    addString(*IMDie, dwarf::DW_AT_name, Name);
+
+  return IMDie;
+}
+
+void DwarfCompileUnit::finishSubprogramDefinition(DISubprogram SP) {
+  DIE *D = getDIE(SP);
+  if (DIE *AbsSPDIE = DU->getAbstractSPDies().lookup(SP)) {
+    if (D)
+      // If this subprogram has an abstract definition, reference that
+      addDIEEntry(*D, dwarf::DW_AT_abstract_origin, *AbsSPDIE);
+  } else {
+    if (!D && !includeMinimalInlineScopes())
+      // Lazily construct the subprogram if we didn't see either concrete or
+      // inlined versions during codegen. (except in -gmlt ^ where we want
+      // to omit these entirely)
+      D = getOrCreateSubprogramDIE(SP);
+    if (D)
+      // And attach the attributes
+      applySubprogramAttributesToDefinition(SP, *D);
+  }
+}
+void DwarfCompileUnit::collectDeadVariables(DISubprogram SP) {
+  assert(SP.isSubprogram() && "CU's subprogram list contains a non-subprogram");
+  assert(SP.isDefinition() &&
+         "CU's subprogram list contains a subprogram declaration");
+  DIArray Variables = SP.getVariables();
+  if (Variables.getNumElements() == 0)
+    return;
+
+  DIE *SPDIE = DU->getAbstractSPDies().lookup(SP);
+  if (!SPDIE)
+    SPDIE = getDIE(SP);
+  assert(SPDIE);
+  for (unsigned vi = 0, ve = Variables.getNumElements(); vi != ve; ++vi) {
+    DIVariable DV(Variables.getElement(vi));
+    assert(DV.isVariable());
+    DbgVariable NewVar(DV, DIExpression(nullptr), DD);
+    auto VariableDie = constructVariableDIE(NewVar);
+    applyVariableAttributes(NewVar, *VariableDie);
+    SPDIE->addChild(std::move(VariableDie));
+  }
+}
+
+void DwarfCompileUnit::emitHeader(const MCSymbol *ASectionSym) const {
+  // Don't bother labeling the .dwo unit, as its offset isn't used.
+  if (!Skeleton)
+    Asm->OutStreamer.EmitLabel(LabelBegin);
+
+  DwarfUnit::emitHeader(ASectionSym);
+}
+
+/// addGlobalName - Add a new global name to the compile unit.
+void DwarfCompileUnit::addGlobalName(StringRef Name, DIE &Die,
+                                     DIScope Context) {
+  if (includeMinimalInlineScopes())
+    return;
+  std::string FullName = getParentContextString(Context) + Name.str();
+  GlobalNames[FullName] = &Die;
+}
+
+/// Add a new global type to the unit.
+void DwarfCompileUnit::addGlobalType(DIType Ty, const DIE &Die,
+                                     DIScope Context) {
+  if (includeMinimalInlineScopes())
+    return;
+  std::string FullName = getParentContextString(Context) + Ty.getName().str();
+  GlobalTypes[FullName] = &Die;
+}
+
+/// addVariableAddress - Add DW_AT_location attribute for a
+/// DbgVariable based on provided MachineLocation.
+void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
+                                          MachineLocation Location) {
+  if (DV.variableHasComplexAddress())
+    addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
+  else if (DV.isBlockByrefVariable())
+    addBlockByrefAddress(DV, Die, dwarf::DW_AT_location, Location);
+  else
+    addAddress(Die, dwarf::DW_AT_location, Location,
+               DV.getVariable().isIndirect());
+}
+
+/// Add an address attribute to a die based on the location provided.
+void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
+                                  const MachineLocation &Location,
+                                  bool Indirect) {
+  DIELoc *Loc = new (DIEValueAllocator) DIELoc();
+
+  if (Location.isReg() && !Indirect)
+    addRegisterOpPiece(*Loc, Location.getReg());
+  else {
+    addRegisterOffset(*Loc, Location.getReg(), Location.getOffset());
+    if (Indirect && !Location.isReg()) {
+      addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
+    }
+  }
+
+  // Now attach the location information to the DIE.
+  addBlock(Die, Attribute, Loc);
+}
+
+/// Start with the address based on the location provided, and generate the
+/// DWARF information necessary to find the actual variable given the extra
+/// address information encoded in the DbgVariable, starting from the starting
+/// location.  Add the DWARF information to the die.
+void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
+                                         dwarf::Attribute Attribute,
+                                         const MachineLocation &Location) {
+  DIELoc *Loc = new (DIEValueAllocator) DIELoc();
+  unsigned N = DV.getNumAddrElements();
+  unsigned i = 0;
+  if (Location.isReg()) {
+    if (N >= 2 && DV.getAddrElement(0) == dwarf::DW_OP_plus) {
+      assert(!DV.getVariable().isIndirect() &&
+             "double indirection not handled");
+      // If first address element is OpPlus then emit
+      // DW_OP_breg + Offset instead of DW_OP_reg + Offset.
+      addRegisterOffset(*Loc, Location.getReg(), DV.getAddrElement(1));
+      i = 2;
+    } else if (N >= 2 && DV.getAddrElement(0) == dwarf::DW_OP_deref) {
+      assert(!DV.getVariable().isIndirect() &&
+             "double indirection not handled");
+      addRegisterOpPiece(*Loc, Location.getReg(),
+                         DV.getExpression().getPieceSize(),
+                         DV.getExpression().getPieceOffset());
+      i = 3;
+    } else
+      addRegisterOpPiece(*Loc, Location.getReg());
+  } else
+    addRegisterOffset(*Loc, Location.getReg(), Location.getOffset());
+
+  for (; i < N; ++i) {
+    uint64_t Element = DV.getAddrElement(i);
+    if (Element == dwarf::DW_OP_plus) {
+      addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_plus_uconst);
+      addUInt(*Loc, dwarf::DW_FORM_udata, DV.getAddrElement(++i));
+
+    } else if (Element == dwarf::DW_OP_deref) {
+      if (!Location.isReg())
+        addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
+
+    } else if (Element == dwarf::DW_OP_piece) {
+      const unsigned SizeOfByte = 8;
+      unsigned PieceOffsetInBits = DV.getAddrElement(++i) * SizeOfByte;
+      unsigned PieceSizeInBits = DV.getAddrElement(++i) * SizeOfByte;
+      // Emit DW_OP_bit_piece Size Offset.
+      assert(PieceSizeInBits > 0 && "piece has zero size");
+      addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_bit_piece);
+      addUInt(*Loc, dwarf::DW_FORM_udata, PieceSizeInBits);
+      addUInt(*Loc, dwarf::DW_FORM_udata, PieceOffsetInBits);
+    } else
+      llvm_unreachable("unknown DIBuilder Opcode");
+  }
+
+  // Now attach the location information to the DIE.
+  addBlock(Die, Attribute, Loc);
+}
+
+/// Add a Dwarf loclistptr attribute data and value.
+void DwarfCompileUnit::addLocationList(DIE &Die, dwarf::Attribute Attribute,
+                                       unsigned Index) {
+  DIEValue *Value = new (DIEValueAllocator) DIELocList(Index);
+  dwarf::Form Form = DD->getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
+                                                : dwarf::DW_FORM_data4;
+  Die.addValue(Attribute, Form, Value);
+}
+
+void DwarfCompileUnit::applyVariableAttributes(const DbgVariable &Var,
+                                               DIE &VariableDie) {
+  StringRef Name = Var.getName();
+  if (!Name.empty())
+    addString(VariableDie, dwarf::DW_AT_name, Name);
+  addSourceLine(VariableDie, Var.getVariable());
+  addType(VariableDie, Var.getType());
+  if (Var.isArtificial())
+    addFlag(VariableDie, dwarf::DW_AT_artificial);
+}
+
+/// Add a Dwarf expression attribute data and value.
+void DwarfCompileUnit::addExpr(DIELoc &Die, dwarf::Form Form,
+                               const MCExpr *Expr) {
+  DIEValue *Value = new (DIEValueAllocator) DIEExpr(Expr);
+  Die.addValue((dwarf::Attribute)0, Form, Value);
+}
+
+void DwarfCompileUnit::applySubprogramAttributesToDefinition(DISubprogram SP,
+                                                             DIE &SPDie) {
+  DISubprogram SPDecl = SP.getFunctionDeclaration();
+  DIScope Context = resolve(SPDecl ? SPDecl.getContext() : SP.getContext());
+  applySubprogramAttributes(SP, SPDie, includeMinimalInlineScopes());
+  addGlobalName(SP.getName(), SPDie, Context);
+}
+
+bool DwarfCompileUnit::isDwoUnit() const {
+  return DD->useSplitDwarf() && Skeleton;
+}
+
+bool DwarfCompileUnit::includeMinimalInlineScopes() const {
+  return getCUNode().getEmissionKind() == DIBuilder::LineTablesOnly ||
+         (DD->useSplitDwarf() && !Skeleton);
+}
+} // end llvm namespace
diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
new file mode 100644
index 0000000..e521f39
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -0,0 +1,250 @@
+//===-- llvm/CodeGen/DwarfCompileUnit.h - Dwarf Compile Unit ---*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing dwarf compile unit.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
+
+#include "DwarfUnit.h"
+#include "llvm/Support/Dwarf.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/IR/DebugInfo.h"
+
+namespace llvm {
+
+class AsmPrinter;
+class DIE;
+class DwarfDebug;
+class DwarfFile;
+class MCSymbol;
+class LexicalScope;
+
+class DwarfCompileUnit : public DwarfUnit {
+  /// The attribute index of DW_AT_stmt_list in the compile unit DIE, avoiding
+  /// the need to search for it in applyStmtList.
+  unsigned stmtListIndex;
+
+  /// Skeleton unit associated with this unit.
+  DwarfCompileUnit *Skeleton;
+
+  /// A label at the start of the non-dwo section related to this unit.
+  MCSymbol *SectionSym;
+
+  /// The start of the unit within its section.
+  MCSymbol *LabelBegin;
+
+  /// GlobalNames - A map of globally visible named entities for this unit.
+  StringMap<const DIE *> GlobalNames;
+
+  /// GlobalTypes - A map of globally visible types for this unit.
+  StringMap<const DIE *> GlobalTypes;
+
+  // List of range lists for a given compile unit, separate from the ranges for
+  // the CU itself.
+  SmallVector<RangeSpanList, 1> CURangeLists;
+
+  // List of ranges for a given compile unit.
+  SmallVector<RangeSpan, 2> CURanges;
+
+  // The base address of this unit, if any. Used for relative references in
+  // ranges/locs.
+  const MCSymbol *BaseAddress;
+
+  /// \brief Construct a DIE for the given DbgVariable without initializing the
+  /// DbgVariable's DIE reference.
+  std::unique_ptr<DIE> constructVariableDIEImpl(const DbgVariable &DV,
+                                                bool Abstract);
+
+  bool isDwoUnit() const override;
+
+  bool includeMinimalInlineScopes() const;
+
+public:
+  DwarfCompileUnit(unsigned UID, DICompileUnit Node, AsmPrinter *A,
+                   DwarfDebug *DW, DwarfFile *DWU);
+
+  DwarfCompileUnit *getSkeleton() const {
+    return Skeleton;
+  }
+
+  void initStmtList(MCSymbol *DwarfLineSectionSym);
+
+  /// Apply the DW_AT_stmt_list from this compile unit to the specified DIE.
+  void applyStmtList(DIE &D);
+
+  /// getOrCreateGlobalVariableDIE - get or create global variable DIE.
+  DIE *getOrCreateGlobalVariableDIE(DIGlobalVariable GV);
+
+  /// addLabelAddress - Add a dwarf label attribute data and value using
+  /// either DW_FORM_addr or DW_FORM_GNU_addr_index.
+  void addLabelAddress(DIE &Die, dwarf::Attribute Attribute,
+                       const MCSymbol *Label);
+
+  /// addLocalLabelAddress - Add a dwarf label attribute data and value using
+  /// DW_FORM_addr only.
+  void addLocalLabelAddress(DIE &Die, dwarf::Attribute Attribute,
+                            const MCSymbol *Label);
+
+  /// addSectionDelta - Add a label delta attribute data and value.
+  void addSectionDelta(DIE &Die, dwarf::Attribute Attribute, const MCSymbol *Hi,
+                       const MCSymbol *Lo);
+
+  DwarfCompileUnit &getCU() override { return *this; }
+
+  unsigned getOrCreateSourceID(StringRef FileName, StringRef DirName) override;
+
+  /// addRange - Add an address range to the list of ranges for this unit.
+  void addRange(RangeSpan Range);
+
+  void attachLowHighPC(DIE &D, const MCSymbol *Begin, const MCSymbol *End);
+
+  /// addSectionLabel - Add a Dwarf section label attribute data and value.
+  ///
+  void addSectionLabel(DIE &Die, dwarf::Attribute Attribute,
+                       const MCSymbol *Label, const MCSymbol *Sec);
+
+  /// \brief 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 &updateSubprogramScopeDIE(DISubprogram SP);
+
+  void constructScopeDIE(LexicalScope *Scope,
+                         SmallVectorImpl<std::unique_ptr<DIE>> &FinalChildren);
+
+  /// \brief A helper function to construct a RangeSpanList for a given
+  /// lexical scope.
+  void addScopeRangeList(DIE &ScopeDIE, SmallVector<RangeSpan, 2> Range);
+
+  void attachRangesOrLowHighPC(DIE &D, SmallVector<RangeSpan, 2> Ranges);
+
+  void attachRangesOrLowHighPC(DIE &D,
+                               const SmallVectorImpl<InsnRange> &Ranges);
+  /// \brief This scope represents inlined body of a function. Construct
+  /// DIE to represent this concrete inlined copy of the function.
+  std::unique_ptr<DIE> constructInlinedScopeDIE(LexicalScope *Scope);
+
+  /// \brief Construct new DW_TAG_lexical_block for this scope and
+  /// attach DW_AT_low_pc/DW_AT_high_pc labels.
+  std::unique_ptr<DIE> constructLexicalScopeDIE(LexicalScope *Scope);
+
+  /// constructVariableDIE - Construct a DIE for the given DbgVariable.
+  std::unique_ptr<DIE> constructVariableDIE(DbgVariable &DV,
+                                            bool Abstract = false);
+
+  std::unique_ptr<DIE> constructVariableDIE(DbgVariable &DV,
+                                            const LexicalScope &Scope,
+                                            DIE *&ObjectPointer);
+
+  /// A helper function to create children of a Scope DIE.
+  DIE *createScopeChildrenDIE(LexicalScope *Scope,
+                              SmallVectorImpl<std::unique_ptr<DIE>> &Children,
+                              unsigned *ChildScopeCount = nullptr);
+
+  /// \brief Construct a DIE for this subprogram scope.
+  void constructSubprogramScopeDIE(LexicalScope *Scope);
+
+  DIE *createAndAddScopeChildren(LexicalScope *Scope, DIE &ScopeDIE);
+
+  void constructAbstractSubprogramScopeDIE(LexicalScope *Scope);
+
+  /// \brief Construct import_module DIE.
+  std::unique_ptr<DIE>
+  constructImportedEntityDIE(const DIImportedEntity &Module);
+
+  void finishSubprogramDefinition(DISubprogram SP);
+
+  void collectDeadVariables(DISubprogram SP);
+
+  /// Set the skeleton unit associated with this unit.
+  void setSkeleton(DwarfCompileUnit &Skel) { Skeleton = &Skel; }
+
+  MCSymbol *getSectionSym() const {
+    assert(Section);
+    return SectionSym;
+  }
+
+  /// Pass in the SectionSym even though we could recreate it in every compile
+  /// unit (type units will have actually distinct symbols once they're in
+  /// comdat sections).
+  void initSection(const MCSection *Section, MCSymbol *SectionSym) {
+    DwarfUnit::initSection(Section);
+    this->SectionSym = SectionSym;
+
+    // Don't bother labeling the .dwo unit, as its offset isn't used.
+    if (!Skeleton)
+      LabelBegin =
+          Asm->GetTempSymbol(Section->getLabelBeginName(), getUniqueID());
+  }
+
+  unsigned getLength() {
+    return sizeof(uint32_t) + // Length field
+        getHeaderSize() + UnitDie.getSize();
+  }
+
+  void emitHeader(const MCSymbol *ASectionSym) const override;
+
+  MCSymbol *getLabelBegin() const {
+    assert(Section);
+    return LabelBegin;
+  }
+
+  /// Add a new global name to the compile unit.
+  void addGlobalName(StringRef Name, DIE &Die, DIScope Context) override;
+
+  /// Add a new global type to the compile unit.
+  void addGlobalType(DIType Ty, const DIE &Die, DIScope Context) override;
+
+  const StringMap<const DIE *> &getGlobalNames() const { return GlobalNames; }
+  const StringMap<const DIE *> &getGlobalTypes() const { return GlobalTypes; }
+
+  /// Add DW_AT_location attribute for a DbgVariable based on provided
+  /// MachineLocation.
+  void addVariableAddress(const DbgVariable &DV, DIE &Die,
+                          MachineLocation Location);
+  /// Add an address attribute to a die based on the location provided.
+  void addAddress(DIE &Die, dwarf::Attribute Attribute,
+                  const MachineLocation &Location, bool Indirect = false);
+
+  /// Start with the address based on the location provided, and generate the
+  /// DWARF information necessary to find the actual variable (navigating the
+  /// extra location information encoded in the type) based on the starting
+  /// location.  Add the DWARF information to the die.
+  void addComplexAddress(const DbgVariable &DV, DIE &Die,
+                         dwarf::Attribute Attribute,
+                         const MachineLocation &Location);
+
+  /// Add a Dwarf loclistptr attribute data and value.
+  void addLocationList(DIE &Die, dwarf::Attribute Attribute, unsigned Index);
+  void applyVariableAttributes(const DbgVariable &Var, DIE &VariableDie);
+
+  /// Add a Dwarf expression attribute data and value.
+  void addExpr(DIELoc &Die, dwarf::Form Form, const MCExpr *Expr);
+
+  void applySubprogramAttributesToDefinition(DISubprogram SP, DIE &SPDie);
+
+  /// getRangeLists - Get the vector of range lists.
+  const SmallVectorImpl<RangeSpanList> &getRangeLists() const {
+    return (Skeleton ? Skeleton : this)->CURangeLists;
+  }
+
+  /// getRanges - Get the list of ranges for this unit.
+  const SmallVectorImpl<RangeSpan> &getRanges() const { return CURanges; }
+  SmallVector<RangeSpan, 2> takeRanges() { return std::move(CURanges); }
+
+  void setBaseAddress(const MCSymbol *Base) { BaseAddress = Base; }
+  const MCSymbol *getBaseAddress() const { return BaseAddress; }
+};
+
+} // end llvm namespace
+
+#endif
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 77860c0..230ea46 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -11,8 +11,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "ByteStreamer.h"
 #include "DwarfDebug.h"
+
+#include "ByteStreamer.h"
+#include "DwarfCompileUnit.h"
 #include "DIE.h"
 #include "DIEHash.h"
 #include "DwarfUnit.h"
@@ -36,6 +38,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Dwarf.h"
+#include "llvm/Support/Endian.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Support/LEB128.h"
@@ -47,6 +50,7 @@
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
 using namespace llvm;
 
 #define DEBUG_TYPE "dwarfdebug"
@@ -149,7 +153,7 @@
     if (tag == dwarf::DW_TAG_pointer_type)
       subType = resolve(DIDerivedType(Ty).getTypeDerivedFrom());
 
-    DIArray Elements = DICompositeType(subType).getTypeArray();
+    DIArray Elements = DICompositeType(subType).getElements();
     for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
       DIDerivedType DT(Elements.getElement(i));
       if (getName() == DT.getName())
@@ -165,10 +169,11 @@
     DwarfAccelTable::Atom(dwarf::DW_ATOM_type_flags, dwarf::DW_FORM_data1)};
 
 DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
-    : Asm(A), MMI(Asm->MMI), FirstCU(nullptr), PrevLabel(nullptr),
-      GlobalRangeCount(0), InfoHolder(A, "info_string", DIEValueAllocator),
+    : Asm(A), MMI(Asm->MMI), PrevLabel(nullptr), GlobalRangeCount(0),
+      InfoHolder(A, *this, "info_string", DIEValueAllocator),
       UsedNonDefaultText(false),
-      SkeletonHolder(A, "skel_string", DIEValueAllocator),
+      SkeletonHolder(A, *this, "skel_string", DIEValueAllocator),
+      IsDarwin(Triple(A->getTargetTriple()).isOSDarwin()),
       AccelNames(DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset,
                                        dwarf::DW_FORM_data4)),
       AccelObjC(DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset,
@@ -188,8 +193,6 @@
 
   // 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 (DwarfAccelTables == Default)
     HasDwarfAccelTables = IsDarwin;
   else
@@ -308,26 +311,6 @@
   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(DwarfCompileUnit &SPCU,
-                                          DISubprogram SP) {
-  DIE *SPDie = SPCU.getOrCreateSubprogramDIE(SP);
-
-  attachLowHighPC(SPCU, *SPDie, FunctionBeginSym, FunctionEndSym);
-
-  const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
-  MachineLocation Location(RI->getFrameRegister(*Asm->MF));
-  SPCU.addAddress(*SPDie, dwarf::DW_AT_frame_base, Location);
-
-  // Add name to the name table, we do this here because we're guaranteed
-  // to have concrete versions of our DW_TAG_subprogram nodes.
-  addSubprogramNames(SP, *SPDie);
-
-  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) {
@@ -344,271 +327,30 @@
 
   // 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;
+  return !getLabelAfterInsn(Ranges.front().second);
 }
 
-static void addSectionLabel(AsmPrinter &Asm, DwarfUnit &U, DIE &D,
-                            dwarf::Attribute A, const MCSymbol *L,
-                            const MCSymbol *Sec) {
-  if (Asm.MAI->doesDwarfUseRelocationsAcrossSections())
-    U.addSectionLabel(D, A, L);
-  else
-    U.addSectionDelta(D, A, L, Sec);
+template <typename Func> void forBothCUs(DwarfCompileUnit &CU, Func F) {
+  F(CU);
+  if (auto *SkelCU = CU.getSkeleton())
+    F(*SkelCU);
 }
 
-void DwarfDebug::addScopeRangeList(DwarfCompileUnit &TheCU, DIE &ScopeDIE,
-                                   const SmallVectorImpl<InsnRange> &Range) {
-  // Emit offset in .debug_range as a relocatable label. emitDIE will handle
-  // emitting it appropriately.
-  MCSymbol *RangeSym = Asm->GetTempSymbol("debug_ranges", GlobalRangeCount++);
-
-  // Under fission, ranges are specified by constant offsets relative to the
-  // CU's DW_AT_GNU_ranges_base.
-  if (useSplitDwarf())
-    TheCU.addSectionDelta(ScopeDIE, dwarf::DW_AT_ranges, RangeSym,
-                          DwarfDebugRangeSectionSym);
-  else
-    addSectionLabel(*Asm, TheCU, ScopeDIE, dwarf::DW_AT_ranges, RangeSym,
-                    DwarfDebugRangeSectionSym);
-
-  RangeSpanList List(RangeSym);
-  for (const InsnRange &R : Range) {
-    RangeSpan Span(getLabelBeforeInsn(R.first), getLabelAfterInsn(R.second));
-    List.addRange(std::move(Span));
-  }
-
-  // Add the range list to the set of ranges to be emitted.
-  TheCU.addRangeList(std::move(List));
-}
-
-void DwarfDebug::attachRangesOrLowHighPC(DwarfCompileUnit &TheCU, DIE &Die,
-                                    const SmallVectorImpl<InsnRange> &Ranges) {
-  assert(!Ranges.empty());
-  if (Ranges.size() == 1)
-    attachLowHighPC(TheCU, Die, getLabelBeforeInsn(Ranges.front().first),
-                    getLabelAfterInsn(Ranges.front().second));
-  else
-    addScopeRangeList(TheCU, Die, Ranges);
-}
-
-// Construct new DW_TAG_lexical_block for this scope and attach
-// DW_AT_low_pc/DW_AT_high_pc labels.
-std::unique_ptr<DIE>
-DwarfDebug::constructLexicalScopeDIE(DwarfCompileUnit &TheCU,
-                                     LexicalScope *Scope) {
-  if (isLexicalScopeDIENull(Scope))
-    return nullptr;
-
-  auto ScopeDIE = make_unique<DIE>(dwarf::DW_TAG_lexical_block);
-  if (Scope->isAbstractScope())
-    return ScopeDIE;
-
-  attachRangesOrLowHighPC(TheCU, *ScopeDIE, Scope->getRanges());
-
-  return ScopeDIE;
-}
-
-// This scope represents inlined body of a function. Construct DIE to
-// represent this concrete inlined copy of the function.
-std::unique_ptr<DIE>
-DwarfDebug::constructInlinedScopeDIE(DwarfCompileUnit &TheCU,
-                                     LexicalScope *Scope) {
-  assert(Scope->getScopeNode());
-  DIScope DS(Scope->getScopeNode());
-  DISubprogram InlinedSP = getDISubprogram(DS);
-  // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
-  // was inlined from another compile unit.
-  DIE *OriginDIE = AbstractSPDies[InlinedSP];
-  assert(OriginDIE && "Unable to find original DIE for an inlined subprogram.");
-
-  auto ScopeDIE = make_unique<DIE>(dwarf::DW_TAG_inlined_subroutine);
-  TheCU.addDIEEntry(*ScopeDIE, dwarf::DW_AT_abstract_origin, *OriginDIE);
-
-  attachRangesOrLowHighPC(TheCU, *ScopeDIE, Scope->getRanges());
-
-  InlinedSubprogramDIEs.insert(OriginDIE);
-
-  // Add the call site information to the DIE.
-  DILocation DL(Scope->getInlinedAt());
-  TheCU.addUInt(*ScopeDIE, dwarf::DW_AT_call_file, None,
-                TheCU.getOrCreateSourceID(DL.getFilename(), DL.getDirectory()));
-  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.
-  addSubprogramNames(InlinedSP, *ScopeDIE);
-
-  return ScopeDIE;
-}
-
-static std::unique_ptr<DIE> constructVariableDIE(DwarfCompileUnit &TheCU,
-                                                 DbgVariable &DV,
-                                                 const LexicalScope &Scope,
-                                                 DIE *&ObjectPointer) {
-  auto Var = TheCU.constructVariableDIE(DV, Scope.isAbstractScope());
-  if (DV.isObjectPointer())
-    ObjectPointer = Var.get();
-  return Var;
-}
-
-DIE *DwarfDebug::createScopeChildrenDIE(
-    DwarfCompileUnit &TheCU, LexicalScope *Scope,
-    SmallVectorImpl<std::unique_ptr<DIE>> &Children) {
-  DIE *ObjectPointer = nullptr;
-
-  // Collect arguments for current function.
-  if (LScopes.isCurrentFunctionScope(Scope)) {
-    for (DbgVariable *ArgDV : CurrentFnArguments)
-      if (ArgDV)
-        Children.push_back(
-            constructVariableDIE(TheCU, *ArgDV, *Scope, ObjectPointer));
-
-    // If this is a variadic function, add an unspecified parameter.
-    DISubprogram SP(Scope->getScopeNode());
-    DIArray FnArgs = SP.getType().getTypeArray();
-    if (FnArgs.getElement(FnArgs.getNumElements() - 1)
-            .isUnspecifiedParameter()) {
-      Children.push_back(
-          make_unique<DIE>(dwarf::DW_TAG_unspecified_parameters));
-    }
-  }
-
-  // Collect lexical scope children first.
-  for (DbgVariable *DV : ScopeVariables.lookup(Scope))
-    Children.push_back(constructVariableDIE(TheCU, *DV, *Scope, ObjectPointer));
-
-  for (LexicalScope *LS : Scope->getChildren())
-    if (std::unique_ptr<DIE> Nested = constructScopeDIE(TheCU, LS))
-      Children.push_back(std::move(Nested));
-  return ObjectPointer;
-}
-
-void DwarfDebug::createAndAddScopeChildren(DwarfCompileUnit &TheCU,
-                                           LexicalScope *Scope, DIE &ScopeDIE) {
-  // We create children when the scope DIE is not null.
-  SmallVector<std::unique_ptr<DIE>, 8> Children;
-  if (DIE *ObjectPointer = createScopeChildrenDIE(TheCU, Scope, Children))
-    TheCU.addDIEEntry(ScopeDIE, dwarf::DW_AT_object_pointer, *ObjectPointer);
-
-  // Add children
-  for (auto &I : Children)
-    ScopeDIE.addChild(std::move(I));
-}
-
-void DwarfDebug::constructAbstractSubprogramScopeDIE(DwarfCompileUnit &TheCU,
-                                                     LexicalScope *Scope) {
+void DwarfDebug::constructAbstractSubprogramScopeDIE(LexicalScope *Scope) {
   assert(Scope && Scope->getScopeNode());
   assert(Scope->isAbstractScope());
   assert(!Scope->getInlinedAt());
 
-  DISubprogram SP(Scope->getScopeNode());
+  const MDNode *SP = Scope->getScopeNode();
 
   ProcessedSPNodes.insert(SP);
 
-  DIE *&AbsDef = AbstractSPDies[SP];
-  if (AbsDef)
-    return;
-
   // Find the subprogram's DwarfCompileUnit in the SPMap in case the subprogram
   // was inlined from another compile unit.
-  DwarfCompileUnit &SPCU = *SPMap[SP];
-  DIE *ContextDIE;
-
-  // Some of this is duplicated from DwarfUnit::getOrCreateSubprogramDIE, with
-  // the important distinction that the DIDescriptor is not associated with the
-  // DIE (since the DIDescriptor will be associated with the concrete DIE, if
-  // any). It could be refactored to some common utility function.
-  if (DISubprogram SPDecl = SP.getFunctionDeclaration()) {
-    ContextDIE = &SPCU.getUnitDie();
-    SPCU.getOrCreateSubprogramDIE(SPDecl);
-  } else
-    ContextDIE = SPCU.getOrCreateContextDIE(resolve(SP.getContext()));
-
-  // Passing null as the associated DIDescriptor because the abstract definition
-  // shouldn't be found by lookup.
-  AbsDef = &SPCU.createAndAddDIE(dwarf::DW_TAG_subprogram, *ContextDIE,
-                                 DIDescriptor());
-  SPCU.applySubprogramAttributesToDefinition(SP, *AbsDef);
-
-  SPCU.addUInt(*AbsDef, dwarf::DW_AT_inline, None, dwarf::DW_INL_inlined);
-  createAndAddScopeChildren(SPCU, Scope, *AbsDef);
-}
-
-DIE &DwarfDebug::constructSubprogramScopeDIE(DwarfCompileUnit &TheCU,
-                                             LexicalScope *Scope) {
-  assert(Scope && Scope->getScopeNode());
-  assert(!Scope->getInlinedAt());
-  assert(!Scope->isAbstractScope());
-  DISubprogram Sub(Scope->getScopeNode());
-
-  assert(Sub.isSubprogram());
-
-  ProcessedSPNodes.insert(Sub);
-
-  DIE &ScopeDIE = updateSubprogramScopeDIE(TheCU, Sub);
-
-  createAndAddScopeChildren(TheCU, Scope, ScopeDIE);
-
-  return ScopeDIE;
-}
-
-// Construct a DIE for this scope.
-std::unique_ptr<DIE> DwarfDebug::constructScopeDIE(DwarfCompileUnit &TheCU,
-                                                   LexicalScope *Scope) {
-  if (!Scope || !Scope->getScopeNode())
-    return nullptr;
-
-  DIScope DS(Scope->getScopeNode());
-
-  assert((Scope->getInlinedAt() || !DS.isSubprogram()) &&
-         "Only handle inlined subprograms here, use "
-         "constructSubprogramScopeDIE for non-inlined "
-         "subprograms");
-
-  SmallVector<std::unique_ptr<DIE>, 8> Children;
-
-  // 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.
-  std::unique_ptr<DIE> ScopeDIE;
-  if (Scope->getParent() && DS.isSubprogram()) {
-    ScopeDIE = constructInlinedScopeDIE(TheCU, Scope);
-    if (!ScopeDIE)
-      return nullptr;
-    // We create children when the scope DIE is not null.
-    createScopeChildrenDIE(TheCU, Scope, Children);
-  } else {
-    // Early exit when we know the scope DIE is going to be null.
-    if (isLexicalScopeDIENull(Scope))
-      return nullptr;
-
-    // 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.
-    createScopeChildrenDIE(TheCU, Scope, Children);
-
-    // 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, nullptr),
-                         less_first());
-    if (Children.empty() && Range.first == Range.second)
-      return nullptr;
-    ScopeDIE = constructLexicalScopeDIE(TheCU, Scope);
-    assert(ScopeDIE && "Scope DIE should not be null.");
-    for (ImportedEntityMap::const_iterator i = Range.first; i != Range.second;
-         ++i)
-      constructImportedEntityDIE(TheCU, i->second, *ScopeDIE);
-  }
-
-  // Add children
-  for (auto &I : Children)
-    ScopeDIE->addChild(std::move(I));
-
-  return ScopeDIE;
+  auto &CU = SPMap[SP];
+  forBothCUs(*CU, [&](DwarfCompileUnit &CU) {
+    CU.constructAbstractSubprogramScopeDIE(Scope);
+  });
 }
 
 void DwarfDebug::addGnuPubAttributes(DwarfUnit &U, DIE &D) const {
@@ -629,6 +371,8 @@
   DwarfCompileUnit &NewCU = *OwnedUnit;
   DIE &Die = NewCU.getUnitDie();
   InfoHolder.addUnit(std::move(OwnedUnit));
+  if (useSplitDwarf())
+    NewCU.setSkeleton(constructSkeletonCU(NewCU));
 
   // LTO with assembly output shares a single line table amongst multiple CUs.
   // To avoid the compilation directory being ambiguous, let the line table
@@ -665,14 +409,10 @@
     NewCU.addUInt(Die, dwarf::DW_AT_APPLE_major_runtime_vers,
                   dwarf::DW_FORM_data1, RVer);
 
-  if (!FirstCU)
-    FirstCU = &NewCU;
-
-  if (useSplitDwarf()) {
+  if (useSplitDwarf())
     NewCU.initSection(Asm->getObjFileLowering().getDwarfInfoDWOSection(),
                       DwarfInfoDWOSectionSym);
-    NewCU.setSkeleton(constructSkeletonCU(NewCU));
-  } else
+  else
     NewCU.initSection(Asm->getObjFileLowering().getDwarfInfoSection(),
                       DwarfInfoSectionSym);
 
@@ -681,44 +421,12 @@
   return NewCU;
 }
 
-void DwarfDebug::constructImportedEntityDIE(DwarfCompileUnit &TheCU,
-                                            const MDNode *N) {
+void DwarfDebug::constructAndAddImportedEntityDIE(DwarfCompileUnit &TheCU,
+                                                  const MDNode *N) {
   DIImportedEntity Module(N);
   assert(Module.Verify());
   if (DIE *D = TheCU.getOrCreateContextDIE(Module.getContext()))
-    constructImportedEntityDIE(TheCU, Module, *D);
-}
-
-void DwarfDebug::constructImportedEntityDIE(DwarfCompileUnit &TheCU,
-                                            const MDNode *N, DIE &Context) {
-  DIImportedEntity Module(N);
-  assert(Module.Verify());
-  return constructImportedEntityDIE(TheCU, Module, Context);
-}
-
-void DwarfDebug::constructImportedEntityDIE(DwarfCompileUnit &TheCU,
-                                            const DIImportedEntity &Module,
-                                            DIE &Context) {
-  assert(Module.Verify() &&
-         "Use one of the MDNode * overloads to handle invalid metadata");
-  DIE &IMDie = TheCU.createAndAddDIE(Module.getTag(), Context, Module);
-  DIE *EntityDie;
-  DIDescriptor Entity = resolve(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);
-  TheCU.addSourceLine(IMDie, Module.getLineNumber(),
-                      Module.getContext().getFilename(),
-                      Module.getContext().getDirectory());
-  TheCU.addDIEEntry(IMDie, dwarf::DW_AT_import, *EntityDie);
-  StringRef Name = Module.getName();
-  if (!Name.empty())
-    TheCU.addString(IMDie, dwarf::DW_AT_name, Name);
+    D->addChild(TheCU.constructImportedEntityDIE(Module));
 }
 
 // Emit all Dwarf sections that should come prior to the content. Create
@@ -732,8 +440,6 @@
 
   FunctionDIs = makeSubprogramMap(*M);
 
-  // If module has named metadata anchors then use them, otherwise scan the
-  // module using debug info finder to collect debug info.
   NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
   if (!CU_Nodes)
     return;
@@ -756,13 +462,18 @@
               ScopesWithImportedEntities.end(), less_first());
     DIArray GVs = CUNode.getGlobalVariables();
     for (unsigned i = 0, e = GVs.getNumElements(); i != e; ++i)
-      CU.createGlobalVariableDIE(DIGlobalVariable(GVs.getElement(i)));
+      CU.getOrCreateGlobalVariableDIE(DIGlobalVariable(GVs.getElement(i)));
     DIArray SPs = CUNode.getSubprograms();
     for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i)
       SPMap.insert(std::make_pair(SPs.getElement(i), &CU));
     DIArray EnumTypes = CUNode.getEnumTypes();
-    for (unsigned i = 0, e = EnumTypes.getNumElements(); i != e; ++i)
-      CU.getOrCreateTypeDIE(EnumTypes.getElement(i));
+    for (unsigned i = 0, e = EnumTypes.getNumElements(); i != e; ++i) {
+      DIType Ty(EnumTypes.getElement(i));
+      // The enum types array by design contains pointers to
+      // MDNodes rather than DIRefs. Unique them here.
+      DIType UniqueTy(resolve(Ty.getRef()));
+      CU.getOrCreateTypeDIE(UniqueTy);
+    }
     DIArray RetainedTypes = CUNode.getRetainedTypes();
     for (unsigned i = 0, e = RetainedTypes.getNumElements(); i != e; ++i) {
       DIType Ty(RetainedTypes.getElement(i));
@@ -774,7 +485,7 @@
     // Emit imported_modules last so that the relevant context is already
     // available.
     for (unsigned i = 0, e = ImportedEntities.getNumElements(); i != e; ++i)
-      constructImportedEntityDIE(CU, ImportedEntities.getElement(i));
+      constructAndAddImportedEntityDIE(CU, ImportedEntities.getElement(i));
   }
 
   // Tell MMI that we have debug info.
@@ -787,9 +498,7 @@
 void DwarfDebug::finishVariableDefinitions() {
   for (const auto &Var : ConcreteVariables) {
     DIE *VariableDie = Var->getDIE();
-    // FIXME: There shouldn't be any variables without DIEs.
-    if (!VariableDie)
-      continue;
+    assert(VariableDie);
     // FIXME: Consider the time-space tradeoff of just storing the unit pointer
     // in the ConcreteVariables list, rather than looking it up again here.
     // DIE::getUnit isn't simple - it walks parent pointers, etc.
@@ -805,36 +514,10 @@
 }
 
 void DwarfDebug::finishSubprogramDefinitions() {
-  const Module *M = MMI->getModule();
-
-  NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu");
-  for (MDNode *N : CU_Nodes->operands()) {
-    DICompileUnit TheCU(N);
-    // Construct subprogram DIE and add variables DIEs.
-    DwarfCompileUnit *SPCU =
-        static_cast<DwarfCompileUnit *>(CUMap.lookup(TheCU));
-    DIArray Subprograms = TheCU.getSubprograms();
-    for (unsigned i = 0, e = Subprograms.getNumElements(); i != e; ++i) {
-      DISubprogram SP(Subprograms.getElement(i));
-      // Perhaps the subprogram is in another CU (such as due to comdat
-      // folding, etc), in which case ignore it here.
-      if (SPMap[SP] != SPCU)
-        continue;
-      DIE *D = SPCU->getDIE(SP);
-      if (DIE *AbsSPDIE = AbstractSPDies.lookup(SP)) {
-        if (D)
-          // If this subprogram has an abstract definition, reference that
-          SPCU->addDIEEntry(*D, dwarf::DW_AT_abstract_origin, *AbsSPDIE);
-      } else {
-        if (!D)
-          // Lazily construct the subprogram if we didn't see either concrete or
-          // inlined versions during codegen.
-          D = SPCU->getOrCreateSubprogramDIE(SP);
-        // And attach the attributes
-        SPCU->applySubprogramAttributesToDefinition(SP, *D);
-      }
-    }
-  }
+  for (const auto &P : SPMap)
+    forBothCUs(*P.second, [&](DwarfCompileUnit &CU) {
+      CU.finishSubprogramDefinition(DISubprogram(P.first));
+    });
 }
 
 
@@ -854,26 +537,7 @@
         DISubprogram SP(Subprograms.getElement(i));
         if (ProcessedSPNodes.count(SP) != 0)
           continue;
-        assert(SP.isSubprogram() &&
-               "CU's subprogram list contains a non-subprogram");
-        assert(SP.isDefinition() &&
-               "CU's subprogram list contains a subprogram declaration");
-        DIArray Variables = SP.getVariables();
-        if (Variables.getNumElements() == 0)
-          continue;
-
-        DIE *SPDIE = AbstractSPDies.lookup(SP);
-        if (!SPDIE)
-          SPDIE = SPCU->getDIE(SP);
-        assert(SPDIE);
-        for (unsigned vi = 0, ve = Variables.getNumElements(); vi != ve; ++vi) {
-          DIVariable DV(Variables.getElement(vi));
-          assert(DV.isVariable());
-          DbgVariable NewVar(DV, this);
-          auto VariableDie = SPCU->constructVariableDIE(NewVar);
-          SPCU->applyVariableAttributes(NewVar, *VariableDie);
-          SPDIE->addChild(std::move(VariableDie));
-        }
+        SPCU->collectDeadVariables(SP);
       }
     }
   }
@@ -889,66 +553,52 @@
 
   // Handle anything that needs to be done on a per-unit basis after
   // all other generation.
-  for (const auto &TheU : getUnits()) {
+  for (const auto &P : CUMap) {
+    auto &TheCU = *P.second;
     // Emit DW_AT_containing_type attribute to connect types with their
     // vtable holding type.
-    TheU->constructContainingTypeDIEs();
+    TheCU.constructContainingTypeDIEs();
 
     // Add CU specific attributes if we need to add any.
-    if (TheU->getUnitDie().getTag() == dwarf::DW_TAG_compile_unit) {
-      // If we're splitting the dwarf out now that we've got the entire
-      // CU then add the dwo id to it.
-      DwarfCompileUnit *SkCU =
-          static_cast<DwarfCompileUnit *>(TheU->getSkeleton());
-      if (useSplitDwarf()) {
-        // Emit a unique identifier for this CU.
-        uint64_t ID = DIEHash(Asm).computeCUSignature(TheU->getUnitDie());
-        TheU->addUInt(TheU->getUnitDie(), dwarf::DW_AT_GNU_dwo_id,
-                      dwarf::DW_FORM_data8, ID);
-        SkCU->addUInt(SkCU->getUnitDie(), dwarf::DW_AT_GNU_dwo_id,
-                      dwarf::DW_FORM_data8, ID);
+    // If we're splitting the dwarf out now that we've got the entire
+    // CU then add the dwo id to it.
+    auto *SkCU = TheCU.getSkeleton();
+    if (useSplitDwarf()) {
+      // Emit a unique identifier for this CU.
+      uint64_t ID = DIEHash(Asm).computeCUSignature(TheCU.getUnitDie());
+      TheCU.addUInt(TheCU.getUnitDie(), dwarf::DW_AT_GNU_dwo_id,
+                    dwarf::DW_FORM_data8, ID);
+      SkCU->addUInt(SkCU->getUnitDie(), dwarf::DW_AT_GNU_dwo_id,
+                    dwarf::DW_FORM_data8, ID);
 
-        // We don't keep track of which addresses are used in which CU so this
-        // is a bit pessimistic under LTO.
-        if (!AddrPool.isEmpty())
-          addSectionLabel(*Asm, *SkCU, SkCU->getUnitDie(),
-                          dwarf::DW_AT_GNU_addr_base, DwarfAddrSectionSym,
-                          DwarfAddrSectionSym);
-        if (!TheU->getRangeLists().empty())
-          addSectionLabel(*Asm, *SkCU, SkCU->getUnitDie(),
-                          dwarf::DW_AT_GNU_ranges_base,
-                          DwarfDebugRangeSectionSym, DwarfDebugRangeSectionSym);
-      }
+      // We don't keep track of which addresses are used in which CU so this
+      // is a bit pessimistic under LTO.
+      if (!AddrPool.isEmpty())
+        SkCU->addSectionLabel(SkCU->getUnitDie(), dwarf::DW_AT_GNU_addr_base,
+                              DwarfAddrSectionSym, DwarfAddrSectionSym);
+      if (!SkCU->getRangeLists().empty())
+        SkCU->addSectionLabel(SkCU->getUnitDie(), dwarf::DW_AT_GNU_ranges_base,
+                              DwarfDebugRangeSectionSym,
+                              DwarfDebugRangeSectionSym);
+    }
 
-      // If we have code split among multiple sections or non-contiguous
-      // ranges of code then emit a DW_AT_ranges attribute on the unit that will
-      // remain in the .o file, otherwise add a DW_AT_low_pc.
-      // FIXME: We should use ranges allow reordering of code ala
-      // .subsections_via_symbols in mach-o. This would mean turning on
-      // ranges for all subprogram DIEs for mach-o.
-      DwarfCompileUnit &U =
-          SkCU ? *SkCU : static_cast<DwarfCompileUnit &>(*TheU);
-      unsigned NumRanges = TheU->getRanges().size();
-      if (NumRanges) {
-        if (NumRanges > 1) {
-          addSectionLabel(*Asm, U, U.getUnitDie(), dwarf::DW_AT_ranges,
-                          Asm->GetTempSymbol("cu_ranges", U.getUniqueID()),
-                          DwarfDebugRangeSectionSym);
-
-          // A DW_AT_low_pc attribute may also be specified in combination with
-          // DW_AT_ranges to specify the default base address for use in
-          // location lists (see Section 2.6.2) and range lists (see Section
-          // 2.17.3).
-          U.addUInt(U.getUnitDie(), dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
-                    0);
-        } else {
-          RangeSpan &Range = TheU->getRanges().back();
-          U.addLocalLabelAddress(U.getUnitDie(), dwarf::DW_AT_low_pc,
-                                 Range.getStart());
-          U.addLabelDelta(U.getUnitDie(), dwarf::DW_AT_high_pc, Range.getEnd(),
-                          Range.getStart());
-        }
-      }
+    // If we have code split among multiple sections or non-contiguous
+    // ranges of code then emit a DW_AT_ranges attribute on the unit that will
+    // remain in the .o file, otherwise add a DW_AT_low_pc.
+    // FIXME: We should use ranges allow reordering of code ala
+    // .subsections_via_symbols in mach-o. This would mean turning on
+    // ranges for all subprogram DIEs for mach-o.
+    DwarfCompileUnit &U = SkCU ? *SkCU : TheCU;
+    if (unsigned NumRanges = TheCU.getRanges().size()) {
+      if (NumRanges > 1)
+        // A DW_AT_low_pc attribute may also be specified in combination with
+        // DW_AT_ranges to specify the default base address for use in
+        // location lists (see Section 2.6.2) and range lists (see Section
+        // 2.17.3).
+        U.addUInt(U.getUnitDie(), dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr, 0);
+      else
+        TheCU.setBaseAddress(TheCU.getRanges().front().getStart());
+      U.attachRangesOrLowHighPC(U.getUnitDie(), TheCU.takeRanges());
     }
   }
 
@@ -1010,7 +660,10 @@
   assert(CurFn == nullptr);
   assert(CurMI == nullptr);
 
-  if (!FirstCU)
+  // If we aren't actually generating debug info (check beginModule -
+  // conditionalized on !DisableDebugInfoPrinting and the presence of the
+  // llvm.dbg.cu metadata node)
+  if (!DwarfInfoSectionSym)
     return;
 
   // End any existing sections.
@@ -1064,9 +717,6 @@
   // clean up.
   SPMap.clear();
   AbstractVariables.clear();
-
-  // Reset these for the next Module if we have one.
-  FirstCU = nullptr;
 }
 
 // Find abstract variable, if any, associated with Var.
@@ -1092,8 +742,8 @@
 
 void DwarfDebug::createAbstractVariable(const DIVariable &Var,
                                         LexicalScope *Scope) {
-  auto AbsDbgVariable = make_unique<DbgVariable>(Var, this);
-  addScopeVariable(Scope, AbsDbgVariable.get());
+  auto AbsDbgVariable = make_unique<DbgVariable>(Var, DIExpression(), this);
+  InfoHolder.addScopeVariable(Scope, AbsDbgVariable.get());
   AbstractVariables[Var] = std::move(AbsDbgVariable);
 }
 
@@ -1117,55 +767,35 @@
     createAbstractVariable(Cleansed, Scope);
 }
 
-// If Var is a current function argument then add it to CurrentFnArguments list.
-bool DwarfDebug::addCurrentFnArgument(DbgVariable *Var, LexicalScope *Scope) {
-  if (!LScopes.isCurrentFunctionScope(Scope))
-    return false;
-  DIVariable DV = Var->getVariable();
-  if (DV.getTag() != dwarf::DW_TAG_arg_variable)
-    return false;
-  unsigned ArgNo = DV.getArgNumber();
-  if (ArgNo == 0)
-    return false;
-
-  size_t Size = CurrentFnArguments.size();
-  if (Size == 0)
-    CurrentFnArguments.resize(CurFn->getFunction()->arg_size());
-  // llvm::Function argument size is not good indicator of how many
-  // arguments does the function have at source level.
-  if (ArgNo > Size)
-    CurrentFnArguments.resize(ArgNo * 2);
-  CurrentFnArguments[ArgNo - 1] = Var;
-  return true;
-}
-
 // Collect variable information from side table maintained by MMI.
 void DwarfDebug::collectVariableInfoFromMMITable(
-    SmallPtrSet<const MDNode *, 16> &Processed) {
+    SmallPtrSetImpl<const MDNode *> &Processed) {
   for (const auto &VI : MMI->getVariableDbgInfo()) {
     if (!VI.Var)
       continue;
     Processed.insert(VI.Var);
-    DIVariable DV(VI.Var);
     LexicalScope *Scope = LScopes.findLexicalScope(VI.Loc);
 
     // If variable scope is not found then skip this variable.
     if (!Scope)
       continue;
 
+    DIVariable DV(VI.Var);
+    DIExpression Expr(VI.Expr);
     ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode());
-    ConcreteVariables.push_back(make_unique<DbgVariable>(DV, this));
+    ConcreteVariables.push_back(make_unique<DbgVariable>(DV, Expr, this));
     DbgVariable *RegVar = ConcreteVariables.back().get();
     RegVar->setFrameIndex(VI.Slot);
-    addScopeVariable(Scope, RegVar);
+    InfoHolder.addScopeVariable(Scope, RegVar);
   }
 }
 
 // Get .debug_loc entry for the instruction range starting at MI.
 static DebugLocEntry::Value getDebugLocValue(const MachineInstr *MI) {
+  const MDNode *Expr = MI->getDebugExpression();
   const MDNode *Var = MI->getDebugVariable();
 
-  assert(MI->getNumOperands() == 3);
+  assert(MI->getNumOperands() == 4);
   if (MI->getOperand(0).isReg()) {
     MachineLocation MLoc;
     // If the second operand is an immediate, this is a
@@ -1174,24 +804,138 @@
       MLoc.set(MI->getOperand(0).getReg());
     else
       MLoc.set(MI->getOperand(0).getReg(), MI->getOperand(1).getImm());
-    return DebugLocEntry::Value(Var, MLoc);
+    return DebugLocEntry::Value(Var, Expr, MLoc);
   }
   if (MI->getOperand(0).isImm())
-    return DebugLocEntry::Value(Var, MI->getOperand(0).getImm());
+    return DebugLocEntry::Value(Var, Expr, MI->getOperand(0).getImm());
   if (MI->getOperand(0).isFPImm())
-    return DebugLocEntry::Value(Var, MI->getOperand(0).getFPImm());
+    return DebugLocEntry::Value(Var, Expr, MI->getOperand(0).getFPImm());
   if (MI->getOperand(0).isCImm())
-    return DebugLocEntry::Value(Var, MI->getOperand(0).getCImm());
+    return DebugLocEntry::Value(Var, Expr, MI->getOperand(0).getCImm());
 
-  llvm_unreachable("Unexpected 3 operand DBG_VALUE instruction!");
+  llvm_unreachable("Unexpected 4-operand DBG_VALUE instruction!");
 }
 
+/// Determine whether two variable pieces overlap.
+static bool piecesOverlap(DIExpression P1, DIExpression P2) {
+  if (!P1.isVariablePiece() || !P2.isVariablePiece())
+    return true;
+  unsigned l1 = P1.getPieceOffset();
+  unsigned l2 = P2.getPieceOffset();
+  unsigned r1 = l1 + P1.getPieceSize();
+  unsigned r2 = l2 + P2.getPieceSize();
+  // True where [l1,r1[ and [r1,r2[ overlap.
+  return (l1 < r2) && (l2 < r1);
+}
+
+/// Build the location list for all DBG_VALUEs in the function that
+/// describe the same variable.  If the ranges of several independent
+/// pieces of the same variable overlap partially, split them up and
+/// combine the ranges. The resulting DebugLocEntries are will have
+/// strict monotonically increasing begin addresses and will never
+/// overlap.
+//
+// Input:
+//
+//   Ranges History [var, loc, piece ofs size]
+// 0 |      [x, (reg0, piece 0, 32)]
+// 1 | |    [x, (reg1, piece 32, 32)] <- IsPieceOfPrevEntry
+// 2 | |    ...
+// 3   |    [clobber reg0]
+// 4        [x, (mem, piece 0, 64)] <- overlapping with both previous pieces of x.
+//
+// Output:
+//
+// [0-1]    [x, (reg0, piece  0, 32)]
+// [1-3]    [x, (reg0, piece  0, 32), (reg1, piece 32, 32)]
+// [3-4]    [x, (reg1, piece 32, 32)]
+// [4- ]    [x, (mem,  piece  0, 64)]
+void
+DwarfDebug::buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
+                              const DbgValueHistoryMap::InstrRanges &Ranges) {
+  SmallVector<DebugLocEntry::Value, 4> OpenRanges;
+
+  for (auto I = Ranges.begin(), E = Ranges.end(); I != E; ++I) {
+    const MachineInstr *Begin = I->first;
+    const MachineInstr *End = I->second;
+    assert(Begin->isDebugValue() && "Invalid History entry");
+
+    // Check if a variable is inaccessible in this range.
+    if (Begin->getNumOperands() > 1 &&
+        Begin->getOperand(0).isReg() && !Begin->getOperand(0).getReg()) {
+      OpenRanges.clear();
+      continue;
+    }
+
+    // If this piece overlaps with any open ranges, truncate them.
+    DIExpression DIExpr = Begin->getDebugExpression();
+    auto Last = std::remove_if(OpenRanges.begin(), OpenRanges.end(),
+                               [&](DebugLocEntry::Value R) {
+      return piecesOverlap(DIExpr, R.getExpression());
+    });
+    OpenRanges.erase(Last, OpenRanges.end());
+
+    const MCSymbol *StartLabel = getLabelBeforeInsn(Begin);
+    assert(StartLabel && "Forgot label before DBG_VALUE starting a range!");
+
+    const MCSymbol *EndLabel;
+    if (End != nullptr)
+      EndLabel = getLabelAfterInsn(End);
+    else if (std::next(I) == Ranges.end())
+      EndLabel = FunctionEndSym;
+    else
+      EndLabel = getLabelBeforeInsn(std::next(I)->first);
+    assert(EndLabel && "Forgot label after instruction ending a range!");
+
+    DEBUG(dbgs() << "DotDebugLoc: " << *Begin << "\n");
+
+    auto Value = getDebugLocValue(Begin);
+    DebugLocEntry Loc(StartLabel, EndLabel, Value);
+    bool couldMerge = false;
+
+    // If this is a piece, it may belong to the current DebugLocEntry.
+    if (DIExpr.isVariablePiece()) {
+      // Add this value to the list of open ranges.
+      OpenRanges.push_back(Value);
+
+      // Attempt to add the piece to the last entry.
+      if (!DebugLoc.empty())
+        if (DebugLoc.back().MergeValues(Loc))
+          couldMerge = true;
+    }
+
+    if (!couldMerge) {
+      // Need to add a new DebugLocEntry. Add all values from still
+      // valid non-overlapping pieces.
+      if (OpenRanges.size())
+        Loc.addValues(OpenRanges);
+
+      DebugLoc.push_back(std::move(Loc));
+    }
+
+    // Attempt to coalesce the ranges of two otherwise identical
+    // DebugLocEntries.
+    auto CurEntry = DebugLoc.rbegin();
+    auto PrevEntry = std::next(CurEntry);
+    if (PrevEntry != DebugLoc.rend() && PrevEntry->MergeRanges(*CurEntry))
+      DebugLoc.pop_back();
+
+    DEBUG({
+      dbgs() << CurEntry->getValues().size() << " Values:\n";
+      for (auto Value : CurEntry->getValues()) {
+        Value.getVariable()->dump();
+        Value.getExpression()->dump();
+      }
+      dbgs() << "-----\n";
+    });
+  }
+}
+
+
 // Find variables for each lexical scope.
 void
-DwarfDebug::collectVariableInfo(SmallPtrSet<const MDNode *, 16> &Processed) {
-  LexicalScope *FnScope = LScopes.getCurrentFunctionScope();
-  DwarfCompileUnit *TheCU = SPMap.lookup(FnScope->getScopeNode());
-
+DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU, DISubprogram SP,
+                                SmallPtrSetImpl<const MDNode *> &Processed) {
   // Grab the variable info that was squirreled away in the MMI side-table.
   collectVariableInfoFromMMITable(Processed);
 
@@ -1206,10 +950,7 @@
       continue;
 
     LexicalScope *Scope = nullptr;
-    if (DV.getTag() == dwarf::DW_TAG_arg_variable &&
-        DISubprogram(DV.getContext()).describes(CurFn->getFunction()))
-      Scope = LScopes.getCurrentFunctionScope();
-    else if (MDNode *IA = DV.getInlinedAt()) {
+    if (MDNode *IA = DV.getInlinedAt()) {
       DebugLoc DL = DebugLoc::getFromDILocation(IA);
       Scope = LScopes.findInlinedScope(DebugLoc::get(
           DL.getLine(), DL.getCol(), DV.getContext(), IA));
@@ -1225,7 +966,7 @@
     ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode());
     ConcreteVariables.push_back(make_unique<DbgVariable>(MInsn, this));
     DbgVariable *RegVar = ConcreteVariables.back().get();
-    addScopeVariable(Scope, RegVar);
+    InfoHolder.addScopeVariable(Scope, RegVar);
 
     // Check if the first DBG_VALUE is valid for the rest of the function.
     if (Ranges.size() == 1 && Ranges.front().second == nullptr)
@@ -1236,53 +977,26 @@
 
     DotDebugLocEntries.resize(DotDebugLocEntries.size() + 1);
     DebugLocList &LocList = DotDebugLocEntries.back();
+    LocList.CU = &TheCU;
     LocList.Label =
         Asm->GetTempSymbol("debug_loc", DotDebugLocEntries.size() - 1);
-    SmallVector<DebugLocEntry, 4> &DebugLoc = LocList.List;
-    for (auto I = Ranges.begin(), E = Ranges.end(); I != E; ++I) {
-      const MachineInstr *Begin = I->first;
-      const MachineInstr *End = I->second;
-      assert(Begin->isDebugValue() && "Invalid History entry");
 
-      // Check if a variable is unaccessible in this range.
-      if (Begin->getNumOperands() > 1 && Begin->getOperand(0).isReg() &&
-          !Begin->getOperand(0).getReg())
-        continue;
-      DEBUG(dbgs() << "DotDebugLoc Pair:\n" << "\t" << *Begin);
-      if (End != nullptr)
-        DEBUG(dbgs() << "\t" << *End);
-      else
-        DEBUG(dbgs() << "\tNULL\n");
-
-      const MCSymbol *StartLabel = getLabelBeforeInsn(Begin);
-      assert(StartLabel && "Forgot label before DBG_VALUE starting a range!");
-
-      const MCSymbol *EndLabel;
-      if (End != nullptr)
-        EndLabel = getLabelAfterInsn(End);
-      else if (std::next(I) == Ranges.end())
-        EndLabel = FunctionEndSym;
-      else
-        EndLabel = getLabelBeforeInsn(std::next(I)->first);
-      assert(EndLabel && "Forgot label after instruction ending a range!");
-
-      DebugLocEntry Loc(StartLabel, EndLabel, getDebugLocValue(Begin), TheCU);
-      if (DebugLoc.empty() || !DebugLoc.back().Merge(Loc))
-        DebugLoc.push_back(std::move(Loc));
-    }
+    // Build the location list for this variable.
+    buildLocationList(LocList.List, Ranges);
   }
 
   // Collect info for variables that were optimized out.
-  DIArray Variables = DISubprogram(FnScope->getScopeNode()).getVariables();
+  DIArray Variables = SP.getVariables();
   for (unsigned i = 0, e = Variables.getNumElements(); i != e; ++i) {
     DIVariable DV(Variables.getElement(i));
     assert(DV.isVariable());
-    if (!Processed.insert(DV))
+    if (!Processed.insert(DV).second)
       continue;
     if (LexicalScope *Scope = LScopes.findLexicalScope(DV.getContext())) {
       ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode());
-      ConcreteVariables.push_back(make_unique<DbgVariable>(DV, this));
-      addScopeVariable(Scope, ConcreteVariables.back().get());
+      DIExpression NoExpr;
+      ConcreteVariables.push_back(make_unique<DbgVariable>(DV, NoExpr, this));
+      InfoHolder.addScopeVariable(Scope, ConcreteVariables.back().get());
     }
   }
 }
@@ -1458,7 +1172,8 @@
   Asm->OutStreamer.EmitLabel(FunctionBeginSym);
 
   // Calculate history for local variables.
-  calculateDbgValueHistory(MF, Asm->TM.getRegisterInfo(), DbgValues);
+  calculateDbgValueHistory(MF, Asm->TM.getSubtargetImpl()->getRegisterInfo(),
+                           DbgValues);
 
   // Request labels for the full history.
   for (const auto &I : DbgValues) {
@@ -1468,10 +1183,24 @@
 
     // The first mention of a function argument gets the FunctionBeginSym
     // label, so arguments are visible when breaking at function entry.
-    DIVariable DV(I.first);
-    if (DV.isVariable() && DV.getTag() == dwarf::DW_TAG_arg_variable &&
-        getDISubprogram(DV.getContext()).describes(MF->getFunction()))
+    DIVariable DIVar(Ranges.front().first->getDebugVariable());
+    if (DIVar.isVariable() && DIVar.getTag() == dwarf::DW_TAG_arg_variable &&
+        getDISubprogram(DIVar.getContext()).describes(MF->getFunction())) {
       LabelsBeforeInsn[Ranges.front().first] = FunctionBeginSym;
+      if (Ranges.front().first->getDebugExpression().isVariablePiece()) {
+        // Mark all non-overlapping initial pieces.
+        for (auto I = Ranges.begin(); I != Ranges.end(); ++I) {
+          DIExpression Piece = I->first->getDebugExpression();
+          if (std::all_of(Ranges.begin(), I,
+                          [&](DbgValueHistoryMap::InstrRange Pred) {
+                return !piecesOverlap(Piece, Pred.first->getDebugExpression());
+              }))
+            LabelsBeforeInsn[I->first] = FunctionBeginSym;
+          else
+            break;
+        }
+      }
+    }
 
     for (const auto &Range : Ranges) {
       requestLabelBeforeInsn(Range.first);
@@ -1497,56 +1226,16 @@
   }
 }
 
-void DwarfDebug::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
-  if (addCurrentFnArgument(Var, LS))
-    return;
-  SmallVectorImpl<DbgVariable *> &Vars = ScopeVariables[LS];
-  DIVariable DV = Var->getVariable();
-  // 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);
-}
-
 // Gather and emit post-function debug information.
 void DwarfDebug::endFunction(const MachineFunction *MF) {
-  // Every beginFunction(MF) call should be followed by an endFunction(MF) call,
-  // though the beginFunction may not be called at all.
-  // We should handle both cases.
-  if (!CurFn)
-    CurFn = MF;
-  else
-    assert(CurFn == MF);
-  assert(CurFn != nullptr);
+  assert(CurFn == MF &&
+      "endFunction should be called with the same function as beginFunction");
 
   if (!MMI->hasDebugInfo() || LScopes.empty() ||
       !FunctionDIs.count(MF->getFunction())) {
     // If we don't have a lexical scope for this function then there will
     // be a hole in the range information. Keep note of this by setting the
     // previously used section to nullptr.
-    PrevSection = nullptr;
     PrevCU = nullptr;
     CurFn = nullptr;
     return;
@@ -1560,45 +1249,63 @@
   // Set DwarfDwarfCompileUnitID in MCContext to default value.
   Asm->OutStreamer.getContext().setDwarfCompileUnitID(0);
 
-  SmallPtrSet<const MDNode *, 16> ProcessedVars;
-  collectVariableInfo(ProcessedVars);
-
   LexicalScope *FnScope = LScopes.getCurrentFunctionScope();
-  DwarfCompileUnit &TheCU = *SPMap.lookup(FnScope->getScopeNode());
+  DISubprogram SP(FnScope->getScopeNode());
+  DwarfCompileUnit &TheCU = *SPMap.lookup(SP);
 
+  SmallPtrSet<const MDNode *, 16> ProcessedVars;
+  collectVariableInfo(TheCU, SP, ProcessedVars);
+
+  // Add the range of this function to the list of ranges for the CU.
+  TheCU.addRange(RangeSpan(FunctionBeginSym, FunctionEndSym));
+
+  // Under -gmlt, skip building the subprogram if there are no inlined
+  // subroutines inside it.
+  if (TheCU.getCUNode().getEmissionKind() == DIBuilder::LineTablesOnly &&
+      LScopes.getAbstractScopesList().empty() && !IsDarwin) {
+    assert(InfoHolder.getScopeVariables().empty());
+    assert(DbgValues.empty());
+    // FIXME: This wouldn't be true in LTO with a -g (with inlining) CU followed
+    // by a -gmlt CU. Add a test and remove this assertion.
+    assert(AbstractVariables.empty());
+    LabelsBeforeInsn.clear();
+    LabelsAfterInsn.clear();
+    PrevLabel = nullptr;
+    CurFn = nullptr;
+    return;
+  }
+
+#ifndef NDEBUG
+  size_t NumAbstractScopes = LScopes.getAbstractScopesList().size();
+#endif
   // Construct abstract scopes.
   for (LexicalScope *AScope : LScopes.getAbstractScopesList()) {
     DISubprogram SP(AScope->getScopeNode());
-    if (!SP.isSubprogram())
-      continue;
+    assert(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));
       assert(DV && DV.isVariable());
-      if (!ProcessedVars.insert(DV))
+      if (!ProcessedVars.insert(DV).second)
         continue;
       ensureAbstractVariableIsCreated(DV, DV.getContext());
+      assert(LScopes.getAbstractScopesList().size() == NumAbstractScopes
+             && "ensureAbstractVariableIsCreated inserted abstract scopes");
     }
-    constructAbstractSubprogramScopeDIE(TheCU, AScope);
+    constructAbstractSubprogramScopeDIE(AScope);
   }
 
-  DIE &CurFnDIE = constructSubprogramScopeDIE(TheCU, FnScope);
-  if (!CurFn->getTarget().Options.DisableFramePointerElim(*CurFn))
-    TheCU.addFlag(CurFnDIE, dwarf::DW_AT_APPLE_omit_frame_ptr);
-
-  // Add the range of this function to the list of ranges for the CU.
-  RangeSpan Span(FunctionBeginSym, FunctionEndSym);
-  TheCU.addRange(std::move(Span));
-  PrevSection = Asm->getCurrentSection();
-  PrevCU = &TheCU;
+  TheCU.constructSubprogramScopeDIE(FnScope);
+  if (auto *SkelCU = TheCU.getSkeleton())
+    if (!LScopes.getAbstractScopesList().empty())
+      SkelCU->constructSubprogramScopeDIE(FnScope);
 
   // Clear debug info
   // Ownership of DbgVariables is a bit subtle - ScopeVariables owns all the
   // DbgVariables except those that are also in AbstractVariables (since they
   // can be used cross-function)
-  ScopeVariables.clear();
-  CurrentFnArguments.clear();
+  InfoHolder.getScopeVariables().clear();
   DbgValues.clear();
   LabelsBeforeInsn.clear();
   LabelsAfterInsn.clear();
@@ -1618,8 +1325,8 @@
     assert(Scope.isScope());
     Fn = Scope.getFilename();
     Dir = Scope.getDirectory();
-    if (Scope.isLexicalBlock())
-      Discriminator = DILexicalBlock(S).getDiscriminator();
+    if (Scope.isLexicalBlockFile())
+      Discriminator = DILexicalBlockFile(S).getDiscriminator();
 
     unsigned CUID = Asm->OutStreamer.getContext().getDwarfCompileUnitID();
     Src = static_cast<DwarfCompileUnit &>(*InfoHolder.getUnits()[CUID])
@@ -1640,9 +1347,12 @@
   // Dwarf sections base addresses.
   DwarfInfoSectionSym =
       emitSectionSym(Asm, TLOF.getDwarfInfoSection(), "section_info");
-  if (useSplitDwarf())
+  if (useSplitDwarf()) {
     DwarfInfoDWOSectionSym =
         emitSectionSym(Asm, TLOF.getDwarfInfoDWOSection(), "section_info_dwo");
+    DwarfTypesDWOSectionSym =
+        emitSectionSym(Asm, TLOF.getDwarfTypesDWOSection(), "section_types_dwo");
+  }
   DwarfAbbrevSectionSym =
       emitSectionSym(Asm, TLOF.getDwarfAbbrevSection(), "section_abbrev");
   if (useSplitDwarf())
@@ -1726,7 +1436,7 @@
 void DwarfDebug::emitDebugInfo() {
   DwarfFile &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
 
-  Holder.emitUnits(this, DwarfAbbrevSectionSym);
+  Holder.emitUnits(DwarfAbbrevSectionSym);
 }
 
 // Emit the abbreviation section.
@@ -1760,54 +1470,41 @@
   Asm->EmitInt8(1);
 }
 
-// Emit visible names into a hashed accelerator table section.
-void DwarfDebug::emitAccelNames() {
-  AccelNames.FinalizeTable(Asm, "Names");
-  Asm->OutStreamer.SwitchSection(
-      Asm->getObjFileLowering().getDwarfAccelNamesSection());
-  MCSymbol *SectionBegin = Asm->GetTempSymbol("names_begin");
+void DwarfDebug::emitAccel(DwarfAccelTable &Accel, const MCSection *Section,
+                           StringRef TableName, StringRef SymName) {
+  Accel.FinalizeTable(Asm, TableName);
+  Asm->OutStreamer.SwitchSection(Section);
+  auto *SectionBegin = Asm->GetTempSymbol(SymName);
   Asm->OutStreamer.EmitLabel(SectionBegin);
 
   // Emit the full data.
-  AccelNames.Emit(Asm, SectionBegin, &InfoHolder);
+  Accel.Emit(Asm, SectionBegin, this, DwarfStrSectionSym);
+}
+
+// Emit visible names into a hashed accelerator table section.
+void DwarfDebug::emitAccelNames() {
+  emitAccel(AccelNames, Asm->getObjFileLowering().getDwarfAccelNamesSection(),
+            "Names", "names_begin");
 }
 
 // Emit objective C classes and categories into a hashed accelerator table
 // section.
 void DwarfDebug::emitAccelObjC() {
-  AccelObjC.FinalizeTable(Asm, "ObjC");
-  Asm->OutStreamer.SwitchSection(
-      Asm->getObjFileLowering().getDwarfAccelObjCSection());
-  MCSymbol *SectionBegin = Asm->GetTempSymbol("objc_begin");
-  Asm->OutStreamer.EmitLabel(SectionBegin);
-
-  // Emit the full data.
-  AccelObjC.Emit(Asm, SectionBegin, &InfoHolder);
+  emitAccel(AccelObjC, Asm->getObjFileLowering().getDwarfAccelObjCSection(),
+            "ObjC", "objc_begin");
 }
 
 // Emit namespace dies into a hashed accelerator table.
 void DwarfDebug::emitAccelNamespaces() {
-  AccelNamespace.FinalizeTable(Asm, "namespac");
-  Asm->OutStreamer.SwitchSection(
-      Asm->getObjFileLowering().getDwarfAccelNamespaceSection());
-  MCSymbol *SectionBegin = Asm->GetTempSymbol("namespac_begin");
-  Asm->OutStreamer.EmitLabel(SectionBegin);
-
-  // Emit the full data.
-  AccelNamespace.Emit(Asm, SectionBegin, &InfoHolder);
+  emitAccel(AccelNamespace,
+            Asm->getObjFileLowering().getDwarfAccelNamespaceSection(),
+            "namespac", "namespac_begin");
 }
 
 // Emit type dies into a hashed accelerator table.
 void DwarfDebug::emitAccelTypes() {
-
-  AccelTypes.FinalizeTable(Asm, "types");
-  Asm->OutStreamer.SwitchSection(
-      Asm->getObjFileLowering().getDwarfAccelTypesSection());
-  MCSymbol *SectionBegin = Asm->GetTempSymbol("types_begin");
-  Asm->OutStreamer.EmitLabel(SectionBegin);
-
-  // Emit the full data.
-  AccelTypes.Emit(Asm, SectionBegin, &InfoHolder);
+  emitAccel(AccelTypes, Asm->getObjFileLowering().getDwarfAccelTypesSection(),
+            "types", "types_begin");
 }
 
 // Public name handling.
@@ -1874,12 +1571,13 @@
       GnuStyle ? Asm->getObjFileLowering().getDwarfGnuPubNamesSection()
                : Asm->getObjFileLowering().getDwarfPubNamesSection();
 
-  emitDebugPubSection(GnuStyle, PSec, "Names", &DwarfUnit::getGlobalNames);
+  emitDebugPubSection(GnuStyle, PSec, "Names",
+                      &DwarfCompileUnit::getGlobalNames);
 }
 
 void DwarfDebug::emitDebugPubSection(
     bool GnuStyle, const MCSection *PSec, StringRef Name,
-    const StringMap<const DIE *> &(DwarfUnit::*Accessor)() const) {
+    const StringMap<const DIE *> &(DwarfCompileUnit::*Accessor)() const) {
   for (const auto &NU : CUMap) {
     DwarfCompileUnit *TheU = NU.second;
 
@@ -1888,7 +1586,7 @@
     if (Globals.empty())
       continue;
 
-    if (auto Skeleton = static_cast<DwarfCompileUnit *>(TheU->getSkeleton()))
+    if (auto *Skeleton = TheU->getSkeleton())
       TheU = Skeleton;
     unsigned ID = TheU->getUniqueID();
 
@@ -1910,7 +1608,7 @@
     Asm->EmitSectionOffset(TheU->getLabelBegin(), TheU->getSectionSym());
 
     Asm->OutStreamer.AddComment("Compilation Unit Length");
-    Asm->EmitLabelDifference(TheU->getLabelEnd(), TheU->getLabelBegin(), 4);
+    Asm->EmitInt32(TheU->getLength());
 
     // Emit the pubnames for this compilation unit.
     for (const auto &GI : Globals) {
@@ -1943,7 +1641,8 @@
       GnuStyle ? Asm->getObjFileLowering().getDwarfGnuPubTypesSection()
                : Asm->getObjFileLowering().getDwarfPubTypesSection();
 
-  emitDebugPubSection(GnuStyle, PSec, "Types", &DwarfUnit::getGlobalTypes);
+  emitDebugPubSection(GnuStyle, PSec, "Types",
+                      &DwarfCompileUnit::getGlobalTypes);
 }
 
 // Emit visible names into a debug str section.
@@ -1952,12 +1651,67 @@
   Holder.emitStrings(Asm->getObjFileLowering().getDwarfStrSection());
 }
 
+/// Emits an optimal (=sorted) sequence of DW_OP_pieces.
+void DwarfDebug::emitLocPieces(ByteStreamer &Streamer,
+                               const DITypeIdentifierMap &Map,
+                               ArrayRef<DebugLocEntry::Value> Values) {
+  assert(std::all_of(Values.begin(), Values.end(), [](DebugLocEntry::Value P) {
+        return P.isVariablePiece();
+      }) && "all values are expected to be pieces");
+  assert(std::is_sorted(Values.begin(), Values.end()) &&
+         "pieces are expected to be sorted");
+
+  unsigned Offset = 0;
+  for (auto Piece : Values) {
+    DIExpression Expr = Piece.getExpression();
+    unsigned PieceOffset = Expr.getPieceOffset();
+    unsigned PieceSize = Expr.getPieceSize();
+    assert(Offset <= PieceOffset && "overlapping or duplicate pieces");
+    if (Offset < PieceOffset) {
+      // The DWARF spec seriously mandates pieces with no locations for gaps.
+      Asm->EmitDwarfOpPiece(Streamer, (PieceOffset-Offset)*8);
+      Offset += PieceOffset-Offset;
+    }
+
+    Offset += PieceSize;
+
+    const unsigned SizeOfByte = 8;
+#ifndef NDEBUG
+    DIVariable Var = Piece.getVariable();
+    assert(!Var.isIndirect() && "indirect address for piece");
+    unsigned VarSize = Var.getSizeInBits(Map);
+    assert(PieceSize+PieceOffset <= VarSize/SizeOfByte
+           && "piece is larger than or outside of variable");
+    assert(PieceSize*SizeOfByte != VarSize
+           && "piece covers entire variable");
+#endif
+    if (Piece.isLocation() && Piece.getLoc().isReg())
+      Asm->EmitDwarfRegOpPiece(Streamer,
+                               Piece.getLoc(),
+                               PieceSize*SizeOfByte);
+    else {
+      emitDebugLocValue(Streamer, Piece);
+      Asm->EmitDwarfOpPiece(Streamer, PieceSize*SizeOfByte);
+    }
+  }
+}
+
+
 void DwarfDebug::emitDebugLocEntry(ByteStreamer &Streamer,
                                    const DebugLocEntry &Entry) {
-  assert(Entry.getValues().size() == 1 &&
-         "multi-value entries are not supported yet.");
   const DebugLocEntry::Value Value = Entry.getValues()[0];
-  DIVariable DV(Value.getVariable());
+  if (Value.isVariablePiece())
+    // Emit all pieces that belong to the same variable and range.
+    return emitLocPieces(Streamer, TypeIdentifierMap, Entry.getValues());
+
+  assert(Entry.getValues().size() == 1 && "only pieces may have >1 value");
+  emitDebugLocValue(Streamer, Value);
+}
+
+void DwarfDebug::emitDebugLocValue(ByteStreamer &Streamer,
+                                   const DebugLocEntry::Value &Value) {
+  DIVariable DV = Value.getVariable();
+  // Regular entry.
   if (Value.isInt()) {
     DIBasicType BTy(resolve(DV.getType()));
     if (BTy.Verify() && (BTy.getEncoding() == dwarf::DW_ATE_signed ||
@@ -1970,24 +1724,25 @@
     }
   } else if (Value.isLocation()) {
     MachineLocation Loc = Value.getLoc();
-    if (!DV.hasComplexAddress())
+    DIExpression Expr = Value.getExpression();
+    if (!Expr)
       // Regular entry.
       Asm->EmitDwarfRegOp(Streamer, Loc, DV.isIndirect());
     else {
       // Complex address entry.
-      unsigned N = DV.getNumAddrElements();
+      unsigned N = Expr.getNumElements();
       unsigned i = 0;
-      if (N >= 2 && DV.getAddrElement(0) == DIBuilder::OpPlus) {
+      if (N >= 2 && Expr.getElement(0) == dwarf::DW_OP_plus) {
         if (Loc.getOffset()) {
           i = 2;
           Asm->EmitDwarfRegOp(Streamer, Loc, DV.isIndirect());
           Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref");
           Streamer.EmitInt8(dwarf::DW_OP_plus_uconst, "DW_OP_plus_uconst");
-          Streamer.EmitSLEB128(DV.getAddrElement(1));
+          Streamer.EmitSLEB128(Expr.getElement(1));
         } else {
           // If first address element is OpPlus then emit
           // DW_OP_breg + Offset instead of DW_OP_reg + Offset.
-          MachineLocation TLoc(Loc.getReg(), DV.getAddrElement(1));
+          MachineLocation TLoc(Loc.getReg(), Expr.getElement(1));
           Asm->EmitDwarfRegOp(Streamer, TLoc, DV.isIndirect());
           i = 2;
         }
@@ -1997,13 +1752,16 @@
 
       // Emit remaining complex address elements.
       for (; i < N; ++i) {
-        uint64_t Element = DV.getAddrElement(i);
-        if (Element == DIBuilder::OpPlus) {
+        uint64_t Element = Expr.getElement(i);
+        if (Element == dwarf::DW_OP_plus) {
           Streamer.EmitInt8(dwarf::DW_OP_plus_uconst, "DW_OP_plus_uconst");
-          Streamer.EmitULEB128(DV.getAddrElement(++i));
-        } else if (Element == DIBuilder::OpDeref) {
+          Streamer.EmitULEB128(Expr.getElement(++i));
+        } else if (Element == dwarf::DW_OP_deref) {
           if (!Loc.isReg())
             Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref");
+        } else if (Element == dwarf::DW_OP_piece) {
+          i += 3;
+          // handled in emitDebugLocEntry.
         } else
           llvm_unreachable("unknown Opcode found in complex address");
       }
@@ -2035,14 +1793,12 @@
   unsigned char Size = Asm->getDataLayout().getPointerSize();
   for (const auto &DebugLoc : DotDebugLocEntries) {
     Asm->OutStreamer.EmitLabel(DebugLoc.Label);
+    const DwarfCompileUnit *CU = DebugLoc.CU;
     for (const auto &Entry : DebugLoc.List) {
       // Set up the range. This range is relative to the entry point of the
       // compile unit. This is a hard coded 0 for low_pc when we're emitting
       // ranges, or the DW_AT_low_pc on the compile unit otherwise.
-      const DwarfCompileUnit *CU = Entry.getCU();
-      if (CU->getRanges().size() == 1) {
-        // Grab the begin symbol from the first range as our base.
-        const MCSymbol *Base = CU->getRanges()[0].getStart();
+      if (auto *Base = CU->getBaseAddress()) {
         Asm->EmitLabelDifference(Entry.getBeginSym(), Base, Size);
         Asm->EmitLabelDifference(Entry.getEndSym(), Base, Size);
       } else {
@@ -2172,6 +1928,10 @@
   for (DwarfCompileUnit *CU : CUs) {
     std::vector<ArangeSpan> &List = Spans[CU];
 
+    // Describe the skeleton CU's offset and length, not the dwo file's.
+    if (auto *Skel = CU->getSkeleton())
+      CU = Skel;
+
     // Emit size of content not including length itself.
     unsigned ContentSize =
         sizeof(int16_t) + // DWARF ARange version number
@@ -2194,7 +1954,7 @@
     Asm->OutStreamer.AddComment("DWARF Arange version number");
     Asm->EmitInt16(dwarf::DW_ARANGES_VERSION);
     Asm->OutStreamer.AddComment("Offset Into Debug Info Section");
-    Asm->EmitSectionOffset(CU->getLocalLabelBegin(), CU->getLocalSectionSym());
+    Asm->EmitSectionOffset(CU->getLabelBegin(), CU->getSectionSym());
     Asm->OutStreamer.AddComment("Address Size (in bytes)");
     Asm->EmitInt8(PtrSize);
     Asm->OutStreamer.AddComment("Segment Size (in bytes)");
@@ -2238,6 +1998,9 @@
   for (const auto &I : CUMap) {
     DwarfCompileUnit *TheCU = I.second;
 
+    if (auto *Skel = TheCU->getSkeleton())
+      TheCU = Skel;
+
     // Iterate over the misc ranges for the compile units in the module.
     for (const RangeSpanList &List : TheCU->getRangeLists()) {
       // Emit our symbol so we can find the beginning of the range.
@@ -2248,9 +2011,7 @@
         const MCSymbol *End = Range.getEnd();
         assert(Begin && "Range without a begin symbol?");
         assert(End && "Range without an end symbol?");
-        if (TheCU->getRanges().size() == 1) {
-          // Grab the begin symbol from the first range as our base.
-          const MCSymbol *Base = TheCU->getRanges()[0].getStart();
+        if (auto *Base = TheCU->getBaseAddress()) {
           Asm->EmitLabelDifference(Begin, Base, Size);
           Asm->EmitLabelDifference(End, Base, Size);
         } else {
@@ -2263,23 +2024,6 @@
       Asm->OutStreamer.EmitIntValue(0, Size);
       Asm->OutStreamer.EmitIntValue(0, Size);
     }
-
-    // Now emit a range for the CU itself.
-    if (TheCU->getRanges().size() > 1) {
-      Asm->OutStreamer.EmitLabel(
-          Asm->GetTempSymbol("cu_ranges", TheCU->getUniqueID()));
-      for (const RangeSpan &Range : TheCU->getRanges()) {
-        const MCSymbol *Begin = Range.getStart();
-        const MCSymbol *End = Range.getEnd();
-        assert(Begin && "Range without a begin symbol?");
-        assert(End && "Range without an end symbol?");
-        Asm->OutStreamer.EmitSymbolValue(Begin, Size);
-        Asm->OutStreamer.EmitSymbolValue(End, Size);
-      }
-      // And terminate the list with two 0 values.
-      Asm->OutStreamer.EmitIntValue(0, Size);
-      Asm->OutStreamer.EmitIntValue(0, Size);
-    }
   }
 }
 
@@ -2287,11 +2031,11 @@
 
 void DwarfDebug::initSkeletonUnit(const DwarfUnit &U, DIE &Die,
                                   std::unique_ptr<DwarfUnit> NewU) {
-  NewU->addLocalString(Die, dwarf::DW_AT_GNU_dwo_name,
-                       U.getCUNode().getSplitDebugFilename());
+  NewU->addString(Die, dwarf::DW_AT_GNU_dwo_name,
+                  U.getCUNode().getSplitDebugFilename());
 
   if (!CompilationDir.empty())
-    NewU->addLocalString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
+    NewU->addString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
 
   addGnuPubAttributes(*NewU, Die);
 
@@ -2316,31 +2060,13 @@
   return NewCU;
 }
 
-// This DIE has the following attributes: DW_AT_comp_dir, DW_AT_dwo_name,
-// DW_AT_addr_base.
-DwarfTypeUnit &DwarfDebug::constructSkeletonTU(DwarfTypeUnit &TU) {
-  DwarfCompileUnit &CU = static_cast<DwarfCompileUnit &>(
-      *SkeletonHolder.getUnits()[TU.getCU().getUniqueID()]);
-
-  auto OwnedUnit = make_unique<DwarfTypeUnit>(TU.getUniqueID(), CU, Asm, this,
-                                              &SkeletonHolder);
-  DwarfTypeUnit &NewTU = *OwnedUnit;
-  NewTU.setTypeSignature(TU.getTypeSignature());
-  NewTU.setType(nullptr);
-  NewTU.initSection(
-      Asm->getObjFileLowering().getDwarfTypesSection(TU.getTypeSignature()));
-
-  initSkeletonUnit(TU, NewTU.getUnitDie(), std::move(OwnedUnit));
-  return NewTU;
-}
-
 // Emit the .debug_info.dwo section for separated dwarf. This contains the
 // compile units that would normally be in debug_info.
 void DwarfDebug::emitDebugInfoDWO() {
   assert(useSplitDwarf() && "No split dwarf debug info?");
   // Don't pass an abbrev symbol, using a constant zero instead so as not to
   // emit relocations into the dwo file.
-  InfoHolder.emitUnits(this, /* AbbrevSymbol */ nullptr);
+  InfoHolder.emitUnits(/* AbbrevSymbol */ nullptr);
 }
 
 // Emit the .debug_abbrev.dwo section for separated dwarf. This contains the
@@ -2364,9 +2090,8 @@
   assert(useSplitDwarf() && "No split dwarf?");
   const MCSection *OffSec =
       Asm->getObjFileLowering().getDwarfStrOffDWOSection();
-  const MCSymbol *StrSym = DwarfStrSectionSym;
   InfoHolder.emitStrings(Asm->getObjFileLowering().getDwarfStrDWOSection(),
-                         OffSec, StrSym);
+                         OffSec);
 }
 
 MCDwarfDwoLineTable *DwarfDebug::getDwoLineTable(const DwarfCompileUnit &CU) {
@@ -2406,9 +2131,9 @@
   bool TopLevelType = TypeUnitsUnderConstruction.empty();
   AddrPool.resetUsedFlag();
 
-  auto OwnedUnit =
-      make_unique<DwarfTypeUnit>(InfoHolder.getUnits().size(), CU, Asm, this,
-                                 &InfoHolder, getDwoLineTable(CU));
+  auto OwnedUnit = make_unique<DwarfTypeUnit>(
+      InfoHolder.getUnits().size() + TypeUnitsUnderConstruction.size(), CU, Asm,
+      this, &InfoHolder, getDwoLineTable(CU));
   DwarfTypeUnit &NewTU = *OwnedUnit;
   DIE &UnitDie = NewTU.getUnitDie();
   TU = &NewTU;
@@ -2421,15 +2146,13 @@
   uint64_t Signature = makeTypeSignature(Identifier);
   NewTU.setTypeSignature(Signature);
 
-  if (!useSplitDwarf())
+  if (useSplitDwarf())
+    NewTU.initSection(Asm->getObjFileLowering().getDwarfTypesDWOSection());
+  else {
     CU.applyStmtList(UnitDie);
-
-  // FIXME: Skip using COMDAT groups for type units in the .dwo file once tools
-  // such as DWP ( http://gcc.gnu.org/wiki/DebugFissionDWP ) can cope with it.
-  NewTU.initSection(
-      useSplitDwarf()
-          ? Asm->getObjFileLowering().getDwarfTypesDWOSection(Signature)
-          : Asm->getObjFileLowering().getDwarfTypesSection(Signature));
+    NewTU.initSection(
+        Asm->getObjFileLowering().getDwarfTypesSection(Signature));
+  }
 
   NewTU.setType(NewTU.createTypeDIE(CTy));
 
@@ -2457,29 +2180,12 @@
 
     // If the type wasn't dependent on fission addresses, finish adding the type
     // and all its dependent types.
-    for (auto &TU : TypeUnitsToAdd) {
-      if (useSplitDwarf())
-        TU.first->setSkeleton(constructSkeletonTU(*TU.first));
+    for (auto &TU : TypeUnitsToAdd)
       InfoHolder.addUnit(std::move(TU.first));
-    }
   }
   CU.addDIETypeSignature(RefDie, NewTU);
 }
 
-void DwarfDebug::attachLowHighPC(DwarfCompileUnit &Unit, DIE &D,
-                                 MCSymbol *Begin, MCSymbol *End) {
-  assert(Begin && "Begin label should not be null!");
-  assert(End && "End label should not be null!");
-  assert(Begin->isDefined() && "Invalid starting label");
-  assert(End->isDefined() && "Invalid end label");
-
-  Unit.addLabelAddress(D, dwarf::DW_AT_low_pc, Begin);
-  if (DwarfVersion < 4)
-    Unit.addLabelAddress(D, dwarf::DW_AT_high_pc, End);
-  else
-    Unit.addLabelDelta(D, dwarf::DW_AT_high_pc, End, Begin);
-}
-
 // Accelerator table mutators - add each name along with its companion
 // DIE to the proper table while ensuring that the name that we're going
 // to reference is in the string table. We do this since the names we
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index ffe4843..48c2809 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -11,8 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_DWARFDEBUG_H__
-#define CODEGEN_ASMPRINTER_DWARFDEBUG_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFDEBUG_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFDEBUG_H
 
 #include "DwarfFile.h"
 #include "AsmPrinterHandler.h"
@@ -70,6 +70,7 @@
 /// \brief This class is used to track local variable information.
 class DbgVariable {
   DIVariable Var;             // Variable Descriptor.
+  DIExpression Expr;          // Complex address location expression.
   DIE *TheDIE;                // Variable DIE.
   unsigned DotDebugLocOffset; // Offset in DotDebugLocEntries.
   const MachineInstr *MInsn;  // DBG_VALUE instruction of the variable.
@@ -78,18 +79,22 @@
 
 public:
   /// Construct a DbgVariable from a DIVariable.
-  DbgVariable(DIVariable V, DwarfDebug *DD)
-      : Var(V), TheDIE(nullptr), DotDebugLocOffset(~0U), MInsn(nullptr),
-        FrameIndex(~0), DD(DD) {}
+  DbgVariable(DIVariable V, DIExpression E, DwarfDebug *DD)
+      : Var(V), Expr(E), TheDIE(nullptr), DotDebugLocOffset(~0U),
+        MInsn(nullptr), FrameIndex(~0), DD(DD) {
+    assert(Var.Verify() && Expr.Verify());
+  }
 
   /// Construct a DbgVariable from a DEBUG_VALUE.
   /// AbstractVar may be NULL.
   DbgVariable(const MachineInstr *DbgValue, DwarfDebug *DD)
-      : Var(DbgValue->getDebugVariable()), TheDIE(nullptr),
-        DotDebugLocOffset(~0U), MInsn(DbgValue), FrameIndex(~0), DD(DD) {}
+      : Var(DbgValue->getDebugVariable()), Expr(DbgValue->getDebugExpression()),
+        TheDIE(nullptr), DotDebugLocOffset(~0U), MInsn(DbgValue),
+        FrameIndex(~0), DD(DD) {}
 
   // Accessors.
   DIVariable getVariable() const { return Var; }
+  DIExpression getExpression() const { return Expr; }
   void setDIE(DIE &D) { TheDIE = &D; }
   DIE *getDIE() const { return TheDIE; }
   void setDotDebugLocOffset(unsigned O) { DotDebugLocOffset = O; }
@@ -124,14 +129,14 @@
 
   bool variableHasComplexAddress() const {
     assert(Var.isVariable() && "Invalid complex DbgVariable!");
-    return Var.hasComplexAddress();
+    return Expr.getNumElements() > 0;
   }
   bool isBlockByrefVariable() const;
   unsigned getNumAddrElements() const {
     assert(Var.isVariable() && "Invalid complex DbgVariable!");
-    return Var.getNumAddrElements();
+    return Expr.getNumElements();
   }
-  uint64_t getAddrElement(unsigned i) const { return Var.getAddrElement(i); }
+  uint64_t getAddrElement(unsigned i) const { return Expr.getElement(i); }
   DIType getType() const;
 
 private:
@@ -159,26 +164,15 @@
   // All DIEValues are allocated through this allocator.
   BumpPtrAllocator DIEValueAllocator;
 
-  // Handle to the compile unit used for the inline extension handling,
-  // this is just so that the DIEValue allocator has a place to store
-  // the particular elements.
-  // FIXME: Store these off of DwarfDebug instead?
-  DwarfCompileUnit *FirstCU;
-
   // Maps MDNode with its corresponding DwarfCompileUnit.
   MapVector<const MDNode *, DwarfCompileUnit *> CUMap;
 
   // Maps subprogram MDNode with its corresponding DwarfCompileUnit.
-  DenseMap<const MDNode *, DwarfCompileUnit *> SPMap;
+  MapVector<const MDNode *, DwarfCompileUnit *> SPMap;
 
   // Maps a CU DIE with its corresponding DwarfCompileUnit.
   DenseMap<const DIE *, DwarfCompileUnit *> CUDieMap;
 
-  /// Maps MDNodes for type system with the corresponding DIEs. These DIEs can
-  /// be shared across CUs, that is why we keep the map here instead
-  /// of in DwarfCompileUnit.
-  DenseMap<const MDNode *, DIE *> MDTypeNodeToDieMap;
-
   // List of all labels used in aranges generation.
   std::vector<SymbolCU> ArangeLabels;
 
@@ -189,19 +183,8 @@
   typedef DenseMap<const MCSection *, SmallVector<SymbolCU, 8> > SectionMapType;
   SectionMapType SectionMap;
 
-  // List of arguments for current function.
-  SmallVector<DbgVariable *, 8> CurrentFnArguments;
-
   LexicalScopes LScopes;
 
-  // Collection of abstract subprogram DIEs.
-  DenseMap<const MDNode *, DIE *> AbstractSPDies;
-
-  // Collection of dbg variables of a scope.
-  typedef DenseMap<LexicalScope *, SmallVector<DbgVariable *, 8> >
-  ScopeVariablesMap;
-  ScopeVariablesMap ScopeVariables;
-
   // Collection of abstract variables.
   DenseMap<const MDNode *, std::unique_ptr<DbgVariable>> AbstractVariables;
   SmallVector<std::unique_ptr<DbgVariable>, 64> ConcreteVariables;
@@ -210,10 +193,6 @@
   // can refer to them in spite of insertions into this list.
   SmallVector<DebugLocList, 4> DotDebugLocEntries;
 
-  // Collection of subprogram DIEs that are marked (at the end of the module)
-  // as DW_AT_inline.
-  SmallPtrSet<DIE *, 4> InlinedSubprogramDIEs;
-
   // This is a collection of subprogram MDNodes that are processed to
   // create DIEs.
   SmallPtrSet<const MDNode *, 16> ProcessedSPNodes;
@@ -243,10 +222,6 @@
   // If nonnull, stores the current machine instruction we're processing.
   const MachineInstr *CurMI;
 
-  // If nonnull, stores the section that the previous function was allocated to
-  // emitting.
-  const MCSection *PrevSection;
-
   // If nonnull, stores the CU in which the previous subprogram was contained.
   const DwarfCompileUnit *PrevCU;
 
@@ -258,6 +233,7 @@
   MCSymbol *DwarfDebugLocSectionSym, *DwarfLineSectionSym, *DwarfAddrSectionSym;
   MCSymbol *FunctionBeginSym, *FunctionEndSym;
   MCSymbol *DwarfInfoDWOSectionSym, *DwarfAbbrevDWOSectionSym;
+  MCSymbol *DwarfTypesDWOSectionSym;
   MCSymbol *DwarfStrDWOSectionSym;
   MCSymbol *DwarfGnuPubNamesSectionSym, *DwarfGnuPubTypesSectionSym;
 
@@ -322,6 +298,7 @@
 
   // True iff there are multiple CUs in this module.
   bool SingleCU;
+  bool IsDarwin;
 
   AddressPool AddrPool;
 
@@ -334,8 +311,6 @@
 
   MCDwarfDwoLineTable *getDwoLineTable(const DwarfCompileUnit &);
 
-  void addScopeVariable(LexicalScope *LS, DbgVariable *Var);
-
   const SmallVectorImpl<std::unique_ptr<DwarfUnit>> &getUnits() {
     return InfoHolder.getUnits();
   }
@@ -350,45 +325,8 @@
   void ensureAbstractVariableIsCreatedIfScoped(const DIVariable &Var,
                                                const MDNode *Scope);
 
-  /// \brief 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 &updateSubprogramScopeDIE(DwarfCompileUnit &SPCU, DISubprogram SP);
-
-  /// \brief A helper function to check whether the DIE for a given Scope is
-  /// going to be null.
-  bool isLexicalScopeDIENull(LexicalScope *Scope);
-
-  /// \brief A helper function to construct a RangeSpanList for a given
-  /// lexical scope.
-  void addScopeRangeList(DwarfCompileUnit &TheCU, DIE &ScopeDIE,
-                         const SmallVectorImpl<InsnRange> &Range);
-
-  /// \brief Construct new DW_TAG_lexical_block for this scope and
-  /// attach DW_AT_low_pc/DW_AT_high_pc labels.
-  std::unique_ptr<DIE> constructLexicalScopeDIE(DwarfCompileUnit &TheCU,
-                                                LexicalScope *Scope);
-
-  /// \brief This scope represents inlined body of a function. Construct
-  /// DIE to represent this concrete inlined copy of the function.
-  std::unique_ptr<DIE> constructInlinedScopeDIE(DwarfCompileUnit &TheCU,
-                                                LexicalScope *Scope);
-
-  /// \brief Construct a DIE for this scope.
-  std::unique_ptr<DIE> constructScopeDIE(DwarfCompileUnit &TheCU,
-                                         LexicalScope *Scope);
-  void createAndAddScopeChildren(DwarfCompileUnit &TheCU, LexicalScope *Scope,
-                                 DIE &ScopeDIE);
   /// \brief Construct a DIE for this abstract scope.
-  void constructAbstractSubprogramScopeDIE(DwarfCompileUnit &TheCU,
-                                           LexicalScope *Scope);
-  /// \brief Construct a DIE for this subprogram scope.
-  DIE &constructSubprogramScopeDIE(DwarfCompileUnit &TheCU,
-                                   LexicalScope *Scope);
-  /// A helper function to create children of a Scope DIE.
-  DIE *createScopeChildrenDIE(DwarfCompileUnit &TheCU, LexicalScope *Scope,
-                              SmallVectorImpl<std::unique_ptr<DIE>> &Children);
+  void constructAbstractSubprogramScopeDIE(LexicalScope *Scope);
 
   /// \brief Emit initial Dwarf sections with a label at the start of each one.
   void emitSectionLabels();
@@ -424,6 +362,10 @@
   /// the line matrix.
   void emitEndOfLineMatrix(unsigned SectionEnd);
 
+  /// \brief Emit a specified accelerator table.
+  void emitAccel(DwarfAccelTable &Accel, const MCSection *Section,
+                 StringRef TableName, StringRef SymName);
+
   /// \brief Emit visible names into a hashed accelerator table section.
   void emitAccelNames();
 
@@ -449,10 +391,9 @@
   /// index.
   void emitDebugPubTypes(bool GnuStyle = false);
 
-  void
-  emitDebugPubSection(bool GnuStyle, const MCSection *PSec, StringRef Name,
-                      const StringMap<const DIE *> &(DwarfUnit::*Accessor)()
-                      const);
+  void emitDebugPubSection(
+      bool GnuStyle, const MCSection *PSec, StringRef Name,
+      const StringMap<const DIE *> &(DwarfCompileUnit::*Accessor)() const);
 
   /// \brief Emit visible names into a debug str section.
   void emitDebugStr();
@@ -507,15 +448,8 @@
   DwarfCompileUnit &constructDwarfCompileUnit(DICompileUnit DIUnit);
 
   /// \brief Construct imported_module or imported_declaration DIE.
-  void constructImportedEntityDIE(DwarfCompileUnit &TheCU, const MDNode *N);
-
-  /// \brief Construct import_module DIE.
-  void constructImportedEntityDIE(DwarfCompileUnit &TheCU, const MDNode *N,
-                                  DIE &Context);
-
-  /// \brief Construct import_module DIE.
-  void constructImportedEntityDIE(DwarfCompileUnit &TheCU,
-                                  const DIImportedEntity &Module, DIE &Context);
+  void constructAndAddImportedEntityDIE(DwarfCompileUnit &TheCU,
+                                        const MDNode *N);
 
   /// \brief Register a source line with debug info. Returns the unique
   /// label that was emitted and which provides correspondence to the
@@ -527,38 +461,29 @@
   /// ending of a scope.
   void identifyScopeMarkers();
 
-  /// \brief If Var is an current function argument that add it in
-  /// CurrentFnArguments list.
-  bool addCurrentFnArgument(DbgVariable *Var, LexicalScope *Scope);
-
   /// \brief Populate LexicalScope entries with variables' info.
-  void collectVariableInfo(SmallPtrSet<const MDNode *, 16> &ProcessedVars);
+  void collectVariableInfo(DwarfCompileUnit &TheCU, DISubprogram SP,
+                           SmallPtrSetImpl<const MDNode *> &ProcessedVars);
+
+  /// \brief Build the location list for all DBG_VALUEs in the
+  /// function that describe the same variable.
+  void buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
+                         const DbgValueHistoryMap::InstrRanges &Ranges);
 
   /// \brief Collect variable information from the side table maintained
   /// by MMI.
-  void collectVariableInfoFromMMITable(SmallPtrSet<const MDNode *, 16> &P);
+  void collectVariableInfoFromMMITable(SmallPtrSetImpl<const MDNode *> &P);
 
   /// \brief Ensure that a label will be emitted before MI.
   void requestLabelBeforeInsn(const MachineInstr *MI) {
     LabelsBeforeInsn.insert(std::make_pair(MI, nullptr));
   }
 
-  /// \brief Return Label preceding the instruction.
-  MCSymbol *getLabelBeforeInsn(const MachineInstr *MI);
-
   /// \brief Ensure that a label will be emitted after MI.
   void requestLabelAfterInsn(const MachineInstr *MI) {
     LabelsAfterInsn.insert(std::make_pair(MI, nullptr));
   }
 
-  /// \brief Return Label immediately following the instruction.
-  MCSymbol *getLabelAfterInsn(const MachineInstr *MI);
-
-  void attachRangesOrLowHighPC(DwarfCompileUnit &Unit, DIE &D,
-                               const SmallVectorImpl<InsnRange> &Ranges);
-  void attachLowHighPC(DwarfCompileUnit &Unit, DIE &D, MCSymbol *Begin,
-                       MCSymbol *End);
-
 public:
   //===--------------------------------------------------------------------===//
   // Main entry points.
@@ -567,13 +492,6 @@
 
   ~DwarfDebug() override;
 
-  void insertDIE(const MDNode *TypeMD, DIE *Die) {
-    MDTypeNodeToDieMap.insert(std::make_pair(TypeMD, Die));
-  }
-  DIE *getDIE(const MDNode *TypeMD) {
-    return MDTypeNodeToDieMap.lookup(TypeMD);
-  }
-
   /// \brief Emit all Dwarf sections that should come prior to the
   /// content.
   void beginModule();
@@ -626,11 +544,15 @@
   /// Returns the section symbol for the .debug_loc section.
   MCSymbol *getDebugLocSym() const { return DwarfDebugLocSectionSym; }
 
-  /// Returns the previous section that was emitted into.
-  const MCSection *getPrevSection() const { return PrevSection; }
+  /// Returns the section symbol for the .debug_str section.
+  MCSymbol *getDebugStrSym() const { return DwarfStrSectionSym; }
+
+  /// Returns the section symbol for the .debug_ranges section.
+  MCSymbol *getRangeSectionSym() const { return DwarfDebugRangeSectionSym; }
 
   /// Returns the previous CU that was being updated
   const DwarfCompileUnit *getPrevCU() const { return PrevCU; }
+  void setPrevCU(const DwarfCompileUnit *PrevCU) { this->PrevCU = PrevCU; }
 
   /// Returns the entries for the .debug_loc section.
   const SmallVectorImpl<DebugLocList> &
@@ -641,6 +563,13 @@
   /// \brief Emit an entry for the debug loc section. This can be used to
   /// handle an entry that's going to be emitted into the debug loc section.
   void emitDebugLocEntry(ByteStreamer &Streamer, const DebugLocEntry &Entry);
+  /// \brief emit a single value for the debug loc section.
+  void emitDebugLocValue(ByteStreamer &Streamer,
+                         const DebugLocEntry::Value &Value);
+  /// Emits an optimal (=sorted) sequence of DW_OP_pieces.
+  void emitLocPieces(ByteStreamer &Streamer,
+                     const DITypeIdentifierMap &Map,
+                     ArrayRef<DebugLocEntry::Value> Values);
 
   /// Emit the location for a debug loc entry, including the size header.
   void emitDebugLocEntryLocation(const DebugLocEntry &Entry);
@@ -674,6 +603,40 @@
   void addAccelNamespace(StringRef Name, const DIE &Die);
 
   void addAccelType(StringRef Name, const DIE &Die, char Flags);
+
+  const MachineFunction *getCurrentFunction() const { return CurFn; }
+  const MCSymbol *getFunctionBeginSym() const { return FunctionBeginSym; }
+  const MCSymbol *getFunctionEndSym() const { return FunctionEndSym; }
+
+  iterator_range<ImportedEntityMap::const_iterator>
+  findImportedEntitiesForScope(const MDNode *Scope) const {
+    return make_range(std::equal_range(
+        ScopesWithImportedEntities.begin(), ScopesWithImportedEntities.end(),
+        std::pair<const MDNode *, const MDNode *>(Scope, nullptr),
+        less_first()));
+  }
+
+  /// \brief A helper function to check whether the DIE for a given Scope is
+  /// going to be null.
+  bool isLexicalScopeDIENull(LexicalScope *Scope);
+
+  /// \brief Return Label preceding the instruction.
+  MCSymbol *getLabelBeforeInsn(const MachineInstr *MI);
+
+  /// \brief Return Label immediately following the instruction.
+  MCSymbol *getLabelAfterInsn(const MachineInstr *MI);
+
+  // FIXME: Consider rolling ranges up into DwarfDebug since we use a single
+  // range_base anyway, so there's no need to keep them as separate per-CU range
+  // lists. (though one day we might end up with a range.dwo section, in which
+  // case it'd go to DwarfFile)
+  unsigned getNextRangeNumber() { return GlobalRangeCount++; }
+
+  // FIXME: Sink these functions down into DwarfFile/Dwarf*Unit.
+
+  SmallPtrSet<const MDNode *, 16> &getProcessedSPNodes() {
+    return ProcessedSPNodes;
+  }
 };
 } // End of namespace llvm
 
diff --git a/lib/CodeGen/AsmPrinter/DwarfException.h b/lib/CodeGen/AsmPrinter/DwarfException.h
index 0440fce..e8867c0 100644
--- a/lib/CodeGen/AsmPrinter/DwarfException.h
+++ b/lib/CodeGen/AsmPrinter/DwarfException.h
@@ -11,8 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_CODEGEN_ASMPRINTER_DWARFEXCEPTION_H
-#define LLVM_CODEGEN_ASMPRINTER_DWARFEXCEPTION_H
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFEXCEPTION_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFEXCEPTION_H
 
 #include "EHStreamer.h"
 #include "llvm/CodeGen/AsmPrinter.h"
@@ -81,39 +81,6 @@
   /// endFunction - Gather and emit post-function exception information.
   void endFunction(const MachineFunction *) override;
 };
-
-class Win64Exception : public EHStreamer {
-  /// shouldEmitPersonality - Per-function flag to indicate if personality
-  /// info should be emitted.
-  bool shouldEmitPersonality;
-
-  /// shouldEmitLSDA - Per-function flag to indicate if the LSDA
-  /// should be emitted.
-  bool shouldEmitLSDA;
-
-  /// shouldEmitMoves - Per-function flag to indicate if frame moves info
-  /// should be emitted.
-  bool shouldEmitMoves;
-
-public:
-  //===--------------------------------------------------------------------===//
-  // Main entry points.
-  //
-  Win64Exception(AsmPrinter *A);
-  virtual ~Win64Exception();
-
-  /// endModule - Emit all exception information that should come after the
-  /// content.
-  void endModule() override;
-
-  /// beginFunction - Gather pre-function exception information.  Assumes being
-  /// emitted immediately after the function entry point.
-  void beginFunction(const MachineFunction *MF) override;
-
-  /// endFunction - Gather and emit post-function exception information.
-  void endFunction(const MachineFunction *) override;
-};
-
 } // End of namespace llvm
 
 #endif
diff --git a/lib/CodeGen/AsmPrinter/DwarfFile.cpp b/lib/CodeGen/AsmPrinter/DwarfFile.cpp
index 737ee54..50180ea 100644
--- a/lib/CodeGen/AsmPrinter/DwarfFile.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfFile.cpp
@@ -18,8 +18,9 @@
 #include "llvm/Target/TargetLoweringObjectFile.h"
 
 namespace llvm {
-DwarfFile::DwarfFile(AsmPrinter *AP, StringRef Pref, BumpPtrAllocator &DA)
-    : Asm(AP), StrPool(DA, *Asm, Pref) {}
+DwarfFile::DwarfFile(AsmPrinter *AP, DwarfDebug &DD, StringRef Pref,
+                     BumpPtrAllocator &DA)
+    : Asm(AP), DD(DD), StrPool(DA, *Asm, Pref) {}
 
 DwarfFile::~DwarfFile() {}
 
@@ -48,25 +49,18 @@
 
 // Emit the various dwarf units to the unit section USection with
 // the abbreviations going into ASection.
-void DwarfFile::emitUnits(DwarfDebug *DD, const MCSymbol *ASectionSym) {
+void DwarfFile::emitUnits(const MCSymbol *ASectionSym) {
   for (const auto &TheU : CUs) {
     DIE &Die = TheU->getUnitDie();
     const MCSection *USection = TheU->getSection();
     Asm->OutStreamer.SwitchSection(USection);
 
-    // Emit the compile units header.
-    Asm->OutStreamer.EmitLabel(TheU->getLabelBegin());
-
-    // Emit size of content not including length itself
-    Asm->OutStreamer.AddComment("Length of Unit");
-    Asm->EmitInt32(TheU->getHeaderSize() + Die.getSize());
-
     TheU->emitHeader(ASectionSym);
 
-    DD->emitDIE(Die);
-    Asm->OutStreamer.EmitLabel(TheU->getLabelEnd());
+    DD.emitDIE(Die);
   }
 }
+
 // Compute the size and offset for each DIE.
 void DwarfFile::computeSizeAndOffsets() {
   // Offset from the first CU in the debug info section is 0 initially.
@@ -149,8 +143,44 @@
 
 // Emit strings into a string section.
 void DwarfFile::emitStrings(const MCSection *StrSection,
-                            const MCSection *OffsetSection,
-                            const MCSymbol *StrSecSym) {
-  StrPool.emit(*Asm, StrSection, OffsetSection, StrSecSym);
+                            const MCSection *OffsetSection) {
+  StrPool.emit(*Asm, StrSection, OffsetSection);
+}
+
+void DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
+  SmallVectorImpl<DbgVariable *> &Vars = ScopeVariables[LS];
+  DIVariable DV = Var->getVariable();
+  // 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.
+    auto 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;
+      // FIXME: There are still some cases where two inlined functions are
+      // conflated together (two calls to the same function at the same
+      // location (eg: via a macro, or without column info, etc)) and then
+      // their arguments are conflated as well.
+      assert((LS->getParent() || CurNum != ArgNum) &&
+             "Duplicate argument for top level (non-inlined) function");
+      ++I;
+    }
+    Vars.insert(I, Var);
+    return;
+  }
+
+  Vars.push_back(Var);
 }
 }
diff --git a/lib/CodeGen/AsmPrinter/DwarfFile.h b/lib/CodeGen/AsmPrinter/DwarfFile.h
index 3985eb2..9d64bfc 100644
--- a/lib/CodeGen/AsmPrinter/DwarfFile.h
+++ b/lib/CodeGen/AsmPrinter/DwarfFile.h
@@ -7,8 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_DWARFFILE_H__
-#define CODEGEN_ASMPRINTER_DWARFFILE_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFFILE_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFFILE_H
 
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/FoldingSet.h"
@@ -24,10 +24,13 @@
 
 namespace llvm {
 class AsmPrinter;
+class DbgVariable;
 class DwarfUnit;
 class DIEAbbrev;
 class MCSymbol;
 class DIE;
+class DISubprogram;
+class LexicalScope;
 class StringRef;
 class DwarfDebug;
 class MCSection;
@@ -35,6 +38,8 @@
   // Target of Dwarf emission, used for sizing of abbreviations.
   AsmPrinter *Asm;
 
+  DwarfDebug &DD;
+
   // Used to uniquely define abbreviations.
   FoldingSet<DIEAbbrev> AbbreviationsSet;
 
@@ -46,8 +51,20 @@
 
   DwarfStringPool StrPool;
 
+  // Collection of dbg variables of a scope.
+  DenseMap<LexicalScope *, SmallVector<DbgVariable *, 8>> ScopeVariables;
+
+  // Collection of abstract subprogram DIEs.
+  DenseMap<const MDNode *, DIE *> AbstractSPDies;
+
+  /// Maps MDNodes for type system with the corresponding DIEs. These DIEs can
+  /// be shared across CUs, that is why we keep the map here instead
+  /// of in DwarfCompileUnit.
+  DenseMap<const MDNode *, DIE *> MDTypeNodeToDieMap;
+
 public:
-  DwarfFile(AsmPrinter *AP, StringRef Pref, BumpPtrAllocator &DA);
+  DwarfFile(AsmPrinter *AP, DwarfDebug &DD, StringRef Pref,
+            BumpPtrAllocator &DA);
 
   ~DwarfFile();
 
@@ -67,18 +84,34 @@
 
   /// \brief Emit all of the units to the section listed with the given
   /// abbreviation section.
-  void emitUnits(DwarfDebug *DD, const MCSymbol *ASectionSym);
+  void emitUnits(const MCSymbol *ASectionSym);
 
   /// \brief Emit a set of abbreviations to the specific section.
   void emitAbbrevs(const MCSection *);
 
   /// \brief Emit all of the strings to the section given.
   void emitStrings(const MCSection *StrSection,
-                   const MCSection *OffsetSection = nullptr,
-                   const MCSymbol *StrSecSym = nullptr);
+                   const MCSection *OffsetSection = nullptr);
 
   /// \brief Returns the string pool.
   DwarfStringPool &getStringPool() { return StrPool; }
+
+  void addScopeVariable(LexicalScope *LS, DbgVariable *Var);
+
+  DenseMap<LexicalScope *, SmallVector<DbgVariable *, 8>> &getScopeVariables() {
+    return ScopeVariables;
+  }
+
+  DenseMap<const MDNode *, DIE *> &getAbstractSPDies() {
+    return AbstractSPDies;
+  }
+
+  void insertDIE(const MDNode *TypeMD, DIE *Die) {
+    MDTypeNodeToDieMap.insert(std::make_pair(TypeMD, Die));
+  }
+  DIE *getDIE(const MDNode *TypeMD) {
+    return MDTypeNodeToDieMap.lookup(TypeMD);
+  }
 };
 }
 #endif
diff --git a/lib/CodeGen/AsmPrinter/DwarfStringPool.cpp b/lib/CodeGen/AsmPrinter/DwarfStringPool.cpp
index 72cab60..d76b66c 100644
--- a/lib/CodeGen/AsmPrinter/DwarfStringPool.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfStringPool.cpp
@@ -12,14 +12,11 @@
 
 using namespace llvm;
 
-MCSymbol *DwarfStringPool::getSectionSymbol() { return SectionSymbol; }
-
 static std::pair<MCSymbol *, unsigned> &
 getEntry(AsmPrinter &Asm,
          StringMap<std::pair<MCSymbol *, unsigned>, BumpPtrAllocator &> &Pool,
          StringRef Prefix, StringRef Str) {
-  std::pair<MCSymbol *, unsigned> &Entry =
-      Pool.GetOrCreateValue(Str).getValue();
+  std::pair<MCSymbol *, unsigned> &Entry = Pool[Str];
   if (!Entry.first) {
     Entry.second = Pool.size() - 1;
     Entry.first = Asm.GetTempSymbol(Prefix, Entry.second);
@@ -36,8 +33,7 @@
 }
 
 void DwarfStringPool::emit(AsmPrinter &Asm, const MCSection *StrSection,
-                           const MCSection *OffsetSection,
-                           const MCSymbol *StrSecSym) {
+                           const MCSection *OffsetSection) {
   if (Pool.empty())
     return;
 
diff --git a/lib/CodeGen/AsmPrinter/DwarfStringPool.h b/lib/CodeGen/AsmPrinter/DwarfStringPool.h
index c1615fb..ab32c1b 100644
--- a/lib/CodeGen/AsmPrinter/DwarfStringPool.h
+++ b/lib/CodeGen/AsmPrinter/DwarfStringPool.h
@@ -7,8 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_STRINGPOOL_H__
-#define CODEGEN_ASMPRINTER_STRINGPOOL_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFSTRINGPOOL_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFSTRINGPOOL_H
 
 #include "llvm/ADT/StringMap.h"
 #include "llvm/CodeGen/AsmPrinter.h"
@@ -28,18 +28,13 @@
 class DwarfStringPool {
   StringMap<std::pair<MCSymbol *, unsigned>, BumpPtrAllocator &> Pool;
   StringRef Prefix;
-  MCSymbol *SectionSymbol;
 
 public:
   DwarfStringPool(BumpPtrAllocator &A, AsmPrinter &Asm, StringRef Prefix)
-      : Pool(A), Prefix(Prefix), SectionSymbol(Asm.GetTempSymbol(Prefix)) {}
+      : Pool(A), Prefix(Prefix) {}
 
   void emit(AsmPrinter &Asm, const MCSection *StrSection,
-            const MCSection *OffsetSection = nullptr,
-            const MCSymbol *StrSecSym = nullptr);
-
-  /// \brief Returns the entry into the start of the pool.
-  MCSymbol *getSectionSymbol();
+            const MCSection *OffsetSection = nullptr);
 
   /// \brief Returns an entry into the string pool with the given
   /// string text.
diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index 9538bee..919d9d2 100644
--- a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -12,7 +12,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "DwarfUnit.h"
+
 #include "DwarfAccelTable.h"
+#include "DwarfCompileUnit.h"
 #include "DwarfDebug.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/IR/Constants.h"
@@ -30,6 +32,7 @@
 #include "llvm/Target/TargetLoweringObjectFile.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
 
 using namespace llvm;
 
@@ -44,20 +47,12 @@
 DwarfUnit::DwarfUnit(unsigned UID, dwarf::Tag UnitTag, DICompileUnit Node,
                      AsmPrinter *A, DwarfDebug *DW, DwarfFile *DWU)
     : UniqueID(UID), CUNode(Node), UnitDie(UnitTag), DebugInfoOffset(0), Asm(A),
-      DD(DW), DU(DWU), IndexTyDie(nullptr), Section(nullptr),
-      Skeleton(nullptr) {
+      DD(DW), DU(DWU), IndexTyDie(nullptr), Section(nullptr) {
   assert(UnitTag == dwarf::DW_TAG_compile_unit ||
          UnitTag == dwarf::DW_TAG_type_unit);
   DIEIntegerOne = new (DIEValueAllocator) DIEInteger(1);
 }
 
-DwarfCompileUnit::DwarfCompileUnit(unsigned UID, DICompileUnit Node,
-                                   AsmPrinter *A, DwarfDebug *DW,
-                                   DwarfFile *DWU)
-    : DwarfUnit(UID, dwarf::DW_TAG_compile_unit, Node, A, DW, DWU) {
-  insertDIE(Node, &getUnitDie());
-}
-
 DwarfTypeUnit::DwarfTypeUnit(unsigned UID, DwarfCompileUnit &CU, AsmPrinter *A,
                              DwarfDebug *DW, DwarfFile *DWU,
                              MCDwarfDwoLineTable *SplitLineTable)
@@ -146,7 +141,7 @@
 /// will be kept in DwarfDebug for shareable DIEs.
 DIE *DwarfUnit::getDIE(DIDescriptor D) const {
   if (isShareableAcrossCUs(D))
-    return DD->getDIE(D);
+    return DU->getDIE(D);
   return MDNodeToDieMap.lookup(D);
 }
 
@@ -155,7 +150,7 @@
 /// will be kept in DwarfDebug for shareable DIEs.
 void DwarfUnit::insertDIE(DIDescriptor Desc, DIE *D) {
   if (isShareableAcrossCUs(Desc)) {
-    DD->insertDIE(Desc, D);
+    DU->insertDIE(Desc, D);
     return;
   }
   MDNodeToDieMap.insert(std::make_pair(Desc, D));
@@ -206,10 +201,14 @@
 /// table.
 void DwarfUnit::addString(DIE &Die, dwarf::Attribute Attribute,
                           StringRef String) {
-
-  if (!DD->useSplitDwarf())
+  if (!isDwoUnit())
     return addLocalString(Die, Attribute, String);
 
+  addIndexedString(Die, Attribute, String);
+}
+
+void DwarfUnit::addIndexedString(DIE &Die, dwarf::Attribute Attribute,
+                                 StringRef String) {
   unsigned idx = DU->getStringPool().getIndex(*Asm, String);
   DIEValue *Value = new (DIEValueAllocator) DIEInteger(idx);
   DIEValue *Str = new (DIEValueAllocator) DIEString(Value, String);
@@ -224,31 +223,12 @@
   DIEValue *Value;
   if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
     Value = new (DIEValueAllocator) DIELabel(Symb);
-  else {
-    MCSymbol *StringPool = DU->getStringPool().getSectionSymbol();
-    Value = new (DIEValueAllocator) DIEDelta(Symb, StringPool);
-  }
+  else
+    Value = new (DIEValueAllocator) DIEDelta(Symb, DD->getDebugStrSym());
   DIEValue *Str = new (DIEValueAllocator) DIEString(Value, String);
   Die.addValue(Attribute, dwarf::DW_FORM_strp, Str);
 }
 
-/// addExpr - Add a Dwarf expression attribute data and value.
-///
-void DwarfUnit::addExpr(DIELoc &Die, dwarf::Form Form, const MCExpr *Expr) {
-  DIEValue *Value = new (DIEValueAllocator) DIEExpr(Expr);
-  Die.addValue((dwarf::Attribute)0, Form, Value);
-}
-
-/// addLocationList - Add a Dwarf loclistptr attribute data and value.
-///
-void DwarfUnit::addLocationList(DIE &Die, dwarf::Attribute Attribute,
-                                unsigned Index) {
-  DIEValue *Value = new (DIEValueAllocator) DIELocList(Index);
-  dwarf::Form Form = DD->getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
-                                                : dwarf::DW_FORM_data4;
-  Die.addValue(Attribute, Form, Value);
-}
-
 /// addLabel - Add a Dwarf label attribute data and value.
 ///
 void DwarfUnit::addLabel(DIE &Die, dwarf::Attribute Attribute, dwarf::Form Form,
@@ -261,16 +241,6 @@
   addLabel(Die, (dwarf::Attribute)0, Form, Label);
 }
 
-/// addSectionLabel - Add a Dwarf section label attribute data and value.
-///
-void DwarfUnit::addSectionLabel(DIE &Die, dwarf::Attribute Attribute,
-                                const MCSymbol *Label) {
-  if (DD->getDwarfVersion() >= 4)
-    addLabel(Die, Attribute, dwarf::DW_FORM_sec_offset, Label);
-  else
-    addLabel(Die, Attribute, dwarf::DW_FORM_data4, Label);
-}
-
 /// addSectionOffset - Add an offset into a section attribute data and value.
 ///
 void DwarfUnit::addSectionOffset(DIE &Die, dwarf::Attribute Attribute,
@@ -281,45 +251,6 @@
     addUInt(Die, Attribute, dwarf::DW_FORM_data4, Integer);
 }
 
-/// addLabelAddress - Add a dwarf label attribute data and value using
-/// DW_FORM_addr or DW_FORM_GNU_addr_index.
-///
-void DwarfCompileUnit::addLabelAddress(DIE &Die, dwarf::Attribute Attribute,
-                                       const MCSymbol *Label) {
-
-  if (!DD->useSplitDwarf())
-    return addLocalLabelAddress(Die, Attribute, Label);
-
-  if (Label)
-    DD->addArangeLabel(SymbolCU(this, Label));
-
-  unsigned idx = DD->getAddressPool().getIndex(Label);
-  DIEValue *Value = new (DIEValueAllocator) DIEInteger(idx);
-  Die.addValue(Attribute, dwarf::DW_FORM_GNU_addr_index, Value);
-}
-
-void DwarfCompileUnit::addLocalLabelAddress(DIE &Die,
-                                            dwarf::Attribute Attribute,
-                                            const MCSymbol *Label) {
-  if (Label)
-    DD->addArangeLabel(SymbolCU(this, Label));
-
-  Die.addValue(Attribute, dwarf::DW_FORM_addr,
-               Label ? (DIEValue *)new (DIEValueAllocator) DIELabel(Label)
-                     : new (DIEValueAllocator) DIEInteger(0));
-}
-
-unsigned DwarfCompileUnit::getOrCreateSourceID(StringRef FileName, StringRef DirName) {
-  // If we print assembly, we can't separate .file entries according to
-  // compile units. Thus all files will belong to the default compile unit.
-
-  // FIXME: add a better feature test than hasRawTextSupport. Even better,
-  // extend .file to support this.
-  return Asm->OutStreamer.EmitDwarfFileDirective(
-      0, DirName, FileName,
-      Asm->OutStreamer.hasRawTextSupport() ? 0 : getUniqueID());
-}
-
 unsigned DwarfTypeUnit::getOrCreateSourceID(StringRef FileName, StringRef DirName) {
   return SplitLineTable ? SplitLineTable->getFile(DirName, FileName)
                         : getCU().getOrCreateSourceID(FileName, DirName);
@@ -339,16 +270,6 @@
   }
 }
 
-/// addSectionDelta - Add a section label delta attribute data and value.
-///
-void DwarfUnit::addSectionDelta(DIE &Die, dwarf::Attribute Attribute,
-                                const MCSymbol *Hi, const MCSymbol *Lo) {
-  DIEValue *Value = new (DIEValueAllocator) DIEDelta(Hi, Lo);
-  Die.addValue(Attribute, DD->getDwarfVersion() >= 4 ? dwarf::DW_FORM_sec_offset
-                                                     : dwarf::DW_FORM_data4,
-               Value);
-}
-
 void DwarfUnit::addLabelDelta(DIE &Die, dwarf::Attribute Attribute,
                               const MCSymbol *Hi, const MCSymbol *Lo) {
   DIEValue *Value = new (DIEValueAllocator) DIEDelta(Hi, Lo);
@@ -477,22 +398,12 @@
   addSourceLine(Die, NS.getLineNumber(), NS.getFilename(), NS.getDirectory());
 }
 
-/// addVariableAddress - Add DW_AT_location attribute for a
-/// DbgVariable based on provided MachineLocation.
-void DwarfUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
-                                   MachineLocation Location) {
-  if (DV.variableHasComplexAddress())
-    addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
-  else if (DV.isBlockByrefVariable())
-    addBlockByrefAddress(DV, Die, dwarf::DW_AT_location, Location);
-  else
-    addAddress(Die, dwarf::DW_AT_location, Location,
-               DV.getVariable().isIndirect());
-}
-
 /// addRegisterOp - Add register operand.
-void DwarfUnit::addRegisterOp(DIELoc &TheDie, unsigned Reg) {
-  const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
+// FIXME: Ideally, this would share the implementation with
+// AsmPrinter::EmitDwarfRegOpPiece.
+void DwarfUnit::addRegisterOpPiece(DIELoc &TheDie, unsigned Reg,
+                                   unsigned SizeInBits, unsigned OffsetInBits) {
+  const TargetRegisterInfo *RI = Asm->TM.getSubtargetImpl()->getRegisterInfo();
   int DWReg = RI->getDwarfRegNum(Reg, false);
   bool isSubRegister = DWReg < 0;
 
@@ -511,7 +422,7 @@
     return;
   }
 
-  // Emit register
+  // Emit register.
   if (DWReg < 32)
     addUInt(TheDie, dwarf::DW_FORM_data1, dwarf::DW_OP_reg0 + DWReg);
   else {
@@ -519,18 +430,34 @@
     addUInt(TheDie, dwarf::DW_FORM_udata, DWReg);
   }
 
-  // Emit Mask
-  if (isSubRegister) {
-    unsigned Size = RI->getSubRegIdxSize(Idx);
-    unsigned Offset = RI->getSubRegIdxOffset(Idx);
-    if (Offset > 0) {
+  // Emit mask.
+  bool isPiece = SizeInBits > 0;
+  if (isSubRegister || isPiece) {
+    const unsigned SizeOfByte = 8;
+    unsigned RegSizeInBits = RI->getSubRegIdxSize(Idx);
+    unsigned RegOffsetInBits = RI->getSubRegIdxOffset(Idx);
+    unsigned PieceSizeInBits = std::max(SizeInBits, RegSizeInBits);
+    unsigned PieceOffsetInBits = OffsetInBits ? OffsetInBits : RegOffsetInBits;
+    assert(RegSizeInBits >= SizeInBits && "register smaller than value");
+
+    if (RegOffsetInBits != PieceOffsetInBits) {
+      // Manually shift the value into place, since the DW_OP_piece
+      // describes the part of the variable, not the position of the
+      // subregister.
+      addUInt(TheDie, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
+      addUInt(TheDie, dwarf::DW_FORM_data1, RegOffsetInBits);
+      addUInt(TheDie, dwarf::DW_FORM_data1, dwarf::DW_OP_shr);
+    }
+
+    if (PieceOffsetInBits > 0 || PieceSizeInBits % SizeOfByte) {
+      assert(PieceSizeInBits > 0 && "piece has zero size");
       addUInt(TheDie, dwarf::DW_FORM_data1, dwarf::DW_OP_bit_piece);
-      addUInt(TheDie, dwarf::DW_FORM_data1, Size);
-      addUInt(TheDie, dwarf::DW_FORM_data1, Offset);
-    } else {
-      unsigned ByteSize = Size / 8; // Assuming 8 bits per byte.
+      addUInt(TheDie, dwarf::DW_FORM_data1, PieceSizeInBits);
+      addUInt(TheDie, dwarf::DW_FORM_data1, PieceOffsetInBits);
+     } else {
+      assert(PieceSizeInBits > 0 && "piece has zero size");
       addUInt(TheDie, dwarf::DW_FORM_data1, dwarf::DW_OP_piece);
-      addUInt(TheDie, dwarf::DW_FORM_data1, ByteSize);
+      addUInt(TheDie, dwarf::DW_FORM_data1, PieceSizeInBits/SizeOfByte);
     }
   }
 }
@@ -538,9 +465,9 @@
 /// addRegisterOffset - Add register offset.
 void DwarfUnit::addRegisterOffset(DIELoc &TheDie, unsigned Reg,
                                   int64_t Offset) {
-  const TargetRegisterInfo *RI = Asm->TM.getRegisterInfo();
+  const TargetRegisterInfo *RI = Asm->TM.getSubtargetImpl()->getRegisterInfo();
   unsigned DWReg = RI->getDwarfRegNum(Reg, false);
-  const TargetRegisterInfo *TRI = Asm->TM.getRegisterInfo();
+  const TargetRegisterInfo *TRI = Asm->TM.getSubtargetImpl()->getRegisterInfo();
   if (Reg == TRI->getFrameRegister(*Asm->MF))
     // If variable offset is based in frame register then use fbreg.
     addUInt(TheDie, dwarf::DW_FORM_data1, dwarf::DW_OP_fbreg);
@@ -553,63 +480,6 @@
   addSInt(TheDie, dwarf::DW_FORM_sdata, Offset);
 }
 
-/// addAddress - Add an address attribute to a die based on the location
-/// provided.
-void DwarfUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
-                           const MachineLocation &Location, bool Indirect) {
-  DIELoc *Loc = new (DIEValueAllocator) DIELoc();
-
-  if (Location.isReg() && !Indirect)
-    addRegisterOp(*Loc, Location.getReg());
-  else {
-    addRegisterOffset(*Loc, Location.getReg(), Location.getOffset());
-    if (Indirect && !Location.isReg()) {
-      addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
-    }
-  }
-
-  // Now attach the location information to the DIE.
-  addBlock(Die, Attribute, Loc);
-}
-
-/// addComplexAddress - Start with the address based on the location provided,
-/// and generate the DWARF information necessary to find the actual variable
-/// given the extra address information encoded in the DbgVariable, starting
-/// from the starting location.  Add the DWARF information to the die.
-///
-void DwarfUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
-                                  dwarf::Attribute Attribute,
-                                  const MachineLocation &Location) {
-  DIELoc *Loc = new (DIEValueAllocator) DIELoc();
-  unsigned N = DV.getNumAddrElements();
-  unsigned i = 0;
-  if (Location.isReg()) {
-    if (N >= 2 && DV.getAddrElement(0) == DIBuilder::OpPlus) {
-      // If first address element is OpPlus then emit
-      // DW_OP_breg + Offset instead of DW_OP_reg + Offset.
-      addRegisterOffset(*Loc, Location.getReg(), DV.getAddrElement(1));
-      i = 2;
-    } else
-      addRegisterOp(*Loc, Location.getReg());
-  } else
-    addRegisterOffset(*Loc, Location.getReg(), Location.getOffset());
-
-  for (; i < N; ++i) {
-    uint64_t Element = DV.getAddrElement(i);
-    if (Element == DIBuilder::OpPlus) {
-      addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_plus_uconst);
-      addUInt(*Loc, dwarf::DW_FORM_udata, DV.getAddrElement(++i));
-    } else if (Element == DIBuilder::OpDeref) {
-      if (!Location.isReg())
-        addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_deref);
-    } else
-      llvm_unreachable("unknown DIBuilder Opcode");
-  }
-
-  // Now attach the location information to the DIE.
-  addBlock(Die, Attribute, Loc);
-}
-
 /* Byref variables, in Blocks, are declared by the programmer as "SomeType
    VarName;", but the compiler creates a __Block_byref_x_VarName struct, and
    gives the variable VarName either the struct, or a pointer to the struct, as
@@ -690,7 +560,7 @@
 
   // Find the __forwarding field and the variable field in the __Block_byref
   // struct.
-  DIArray Fields = blockStruct.getTypeArray();
+  DIArray Fields = blockStruct.getElements();
   DIDerivedType varField;
   DIDerivedType forwardingField;
 
@@ -712,7 +582,7 @@
   DIELoc *Loc = new (DIEValueAllocator) DIELoc();
 
   if (Location.isReg())
-    addRegisterOp(*Loc, Location.getReg());
+    addRegisterOpPiece(*Loc, Location.getReg());
   else
     addRegisterOffset(*Loc, Location.getReg(), Location.getOffset());
 
@@ -1002,11 +872,9 @@
     unsigned Flags = IsImplementation ? dwarf::DW_FLAG_type_implementation : 0;
     DD->addAccelType(Ty.getName(), TyDIE, Flags);
 
-    if ((!Context || Context.isCompileUnit() || Context.isFile() ||
-         Context.isNameSpace()) &&
-        getCUNode().getEmissionKind() != DIBuilder::LineTablesOnly)
-      GlobalTypes[getParentContextString(Context) + Ty.getName().str()] =
-          &TyDIE;
+    if (!Context || Context.isCompileUnit() || Context.isFile() ||
+        Context.isNameSpace())
+      addGlobalType(Ty, TyDIE, Context);
   }
 }
 
@@ -1031,14 +899,6 @@
   addDIEEntry(Entity, Attribute, Entry);
 }
 
-/// addGlobalName - Add a new global name to the compile unit.
-void DwarfUnit::addGlobalName(StringRef Name, DIE &Die, DIScope Context) {
-  if (getCUNode().getEmissionKind() == DIBuilder::LineTablesOnly)
-    return;
-  std::string FullName = getParentContextString(Context) + Name.str();
-  GlobalNames[FullName] = &Die;
-}
-
 /// getParentContextString - Walks the metadata parent chain in a language
 /// specific manner (using the compile unit language) and returns
 /// it as a string. This is done at the metadata level because DIEs may
@@ -1129,16 +989,16 @@
 }
 
 /// constructSubprogramArguments - Construct function argument DIEs.
-void DwarfUnit::constructSubprogramArguments(DIE &Buffer, DIArray Args) {
+void DwarfUnit::constructSubprogramArguments(DIE &Buffer, DITypeArray Args) {
   for (unsigned i = 1, N = Args.getNumElements(); i < N; ++i) {
-    DIDescriptor Ty = Args.getElement(i);
-    if (Ty.isUnspecifiedParameter()) {
+    DIType Ty = resolve(Args.getElement(i));
+    if (!Ty) {
       assert(i == N-1 && "Unspecified parameter must be the last argument");
       createAndAddDIE(dwarf::DW_TAG_unspecified_parameters, Buffer);
     } else {
       DIE &Arg = createAndAddDIE(dwarf::DW_TAG_formal_parameter, Buffer);
-      addType(Arg, DIType(Ty));
-      if (DIType(Ty).isArtificial())
+      addType(Arg, Ty);
+      if (Ty.isArtificial())
         addFlag(Arg, dwarf::DW_AT_artificial);
     }
   }
@@ -1161,14 +1021,14 @@
     break;
   case dwarf::DW_TAG_subroutine_type: {
     // Add return type. A void return won't have a type.
-    DIArray Elements = CTy.getTypeArray();
-    DIType RTy(Elements.getElement(0));
+    DITypeArray Elements = DISubroutineType(CTy).getTypeArray();
+    DIType RTy(resolve(Elements.getElement(0)));
     if (RTy)
       addType(Buffer, RTy);
 
     bool isPrototyped = true;
     if (Elements.getNumElements() == 2 &&
-        Elements.getElement(1).isUnspecifiedParameter())
+        !Elements.getElement(1))
       isPrototyped = false;
 
     constructSubprogramArguments(Buffer, Elements);
@@ -1191,7 +1051,7 @@
   case dwarf::DW_TAG_union_type:
   case dwarf::DW_TAG_class_type: {
     // Add elements to structure type.
-    DIArray Elements = CTy.getTypeArray();
+    DIArray Elements = CTy.getElements();
     for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
       DIDescriptor Element = Elements.getElement(i);
       if (Element.isSubprogram())
@@ -1373,20 +1233,23 @@
 }
 
 /// getOrCreateSubprogramDIE - Create new DIE using SP.
-DIE *DwarfUnit::getOrCreateSubprogramDIE(DISubprogram SP) {
+DIE *DwarfUnit::getOrCreateSubprogramDIE(DISubprogram SP, bool Minimal) {
   // Construct the context before querying for the existence of the DIE in case
   // such construction creates the DIE (as is the case for member function
   // declarations).
-  DIE *ContextDIE = getOrCreateContextDIE(resolve(SP.getContext()));
+  DIE *ContextDIE =
+      Minimal ? &getUnitDie() : getOrCreateContextDIE(resolve(SP.getContext()));
 
   if (DIE *SPDie = getDIE(SP))
     return SPDie;
 
   if (DISubprogram SPDecl = SP.getFunctionDeclaration()) {
-    // Add subprogram definitions to the CU die directly.
-    ContextDIE = &getUnitDie();
-    // Build the decl now to ensure it precedes the definition.
-    getOrCreateSubprogramDIE(SPDecl);
+    if (!Minimal) {
+      // Add subprogram definitions to the CU die directly.
+      ContextDIE = &getUnitDie();
+      // Build the decl now to ensure it precedes the definition.
+      getOrCreateSubprogramDIE(SPDecl);
+    }
   }
 
   // DW_TAG_inlined_subroutine may refer to this DIE.
@@ -1401,14 +1264,8 @@
   return &SPDie;
 }
 
-void DwarfUnit::applySubprogramAttributesToDefinition(DISubprogram SP, DIE &SPDie) {
-  DISubprogram SPDecl = SP.getFunctionDeclaration();
-  DIScope Context = resolve(SPDecl ? SPDecl.getContext() : SP.getContext());
-  applySubprogramAttributes(SP, SPDie);
-  addGlobalName(SP.getName(), SPDie, Context);
-}
-
-void DwarfUnit::applySubprogramAttributes(DISubprogram SP, DIE &SPDie) {
+bool DwarfUnit::applySubprogramDefinitionAttributes(DISubprogram SP,
+                                                    DIE &SPDie) {
   DIE *DeclDie = nullptr;
   StringRef DeclLinkageName;
   if (DISubprogram SPDecl = SP.getFunctionDeclaration()) {
@@ -1431,17 +1288,29 @@
     addString(SPDie, dwarf::DW_AT_MIPS_linkage_name,
               GlobalValue::getRealLinkageName(LinkageName));
 
-  if (DeclDie) {
-    // Refer to the function declaration where all the other attributes will be
-    // found.
-    addDIEEntry(SPDie, dwarf::DW_AT_specification, *DeclDie);
-    return;
-  }
+  if (!DeclDie)
+    return false;
+
+  // Refer to the function declaration where all the other attributes will be
+  // found.
+  addDIEEntry(SPDie, dwarf::DW_AT_specification, *DeclDie);
+  return true;
+}
+
+void DwarfUnit::applySubprogramAttributes(DISubprogram SP, DIE &SPDie,
+                                          bool Minimal) {
+  if (!Minimal)
+    if (applySubprogramDefinitionAttributes(SP, SPDie))
+      return;
 
   // Constructors and operators for anonymous aggregates do not have names.
   if (!SP.getName().empty())
     addString(SPDie, dwarf::DW_AT_name, SP.getName());
 
+  // Skip the rest of the attributes under -gmlt to save space.
+  if (Minimal)
+    return;
+
   addSourceLine(SPDie, SP);
 
   // Add the prototype if we have a prototype and we have a C like
@@ -1452,15 +1321,15 @@
        Language == dwarf::DW_LANG_ObjC))
     addFlag(SPDie, dwarf::DW_AT_prototyped);
 
-  DICompositeType SPTy = SP.getType();
+  DISubroutineType SPTy = SP.getType();
   assert(SPTy.getTag() == dwarf::DW_TAG_subroutine_type &&
          "the type of a subprogram should be a subroutine");
 
-  DIArray Args = SPTy.getTypeArray();
+  DITypeArray Args = SPTy.getTypeArray();
   // Add a return type. If this is a type like a C/C++ void type we don't add a
   // return type.
-  if (Args.getElement(0))
-    addType(SPDie, DIType(Args.getElement(0)));
+  if (resolve(Args.getElement(0)))
+    addType(SPDie, DIType(resolve(Args.getElement(0))));
 
   unsigned VK = SP.getVirtuality();
   if (VK) {
@@ -1506,7 +1375,7 @@
   else if (SP.isPrivate())
     addUInt(SPDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_data1,
             dwarf::DW_ACCESS_private);
-  else
+  else if (SP.isPublic())
     addUInt(SPDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_data1,
             dwarf::DW_ACCESS_public);
 
@@ -1514,184 +1383,6 @@
     addFlag(SPDie, dwarf::DW_AT_explicit);
 }
 
-void DwarfUnit::applyVariableAttributes(const DbgVariable &Var,
-                                        DIE &VariableDie) {
-  StringRef Name = Var.getName();
-  if (!Name.empty())
-    addString(VariableDie, dwarf::DW_AT_name, Name);
-  addSourceLine(VariableDie, Var.getVariable());
-  addType(VariableDie, Var.getType());
-  if (Var.isArtificial())
-    addFlag(VariableDie, dwarf::DW_AT_artificial);
-}
-
-// Return const expression if value is a GEP to access merged global
-// constant. e.g.
-// i8* getelementptr ({ i8, i8, i8, i8 }* @_MergedGlobals, i32 0, i32 0)
-static const ConstantExpr *getMergedGlobalExpr(const Value *V) {
-  const ConstantExpr *CE = dyn_cast_or_null<ConstantExpr>(V);
-  if (!CE || CE->getNumOperands() != 3 ||
-      CE->getOpcode() != Instruction::GetElementPtr)
-    return nullptr;
-
-  // First operand points to a global struct.
-  Value *Ptr = CE->getOperand(0);
-  if (!isa<GlobalValue>(Ptr) ||
-      !isa<StructType>(cast<PointerType>(Ptr->getType())->getElementType()))
-    return nullptr;
-
-  // Second operand is zero.
-  const ConstantInt *CI = dyn_cast_or_null<ConstantInt>(CE->getOperand(1));
-  if (!CI || !CI->isZero())
-    return nullptr;
-
-  // Third operand is offset.
-  if (!isa<ConstantInt>(CE->getOperand(2)))
-    return nullptr;
-
-  return CE;
-}
-
-/// createGlobalVariableDIE - create global variable DIE.
-void DwarfCompileUnit::createGlobalVariableDIE(DIGlobalVariable GV) {
-  // Check for pre-existence.
-  if (getDIE(GV))
-    return;
-
-  assert(GV.isGlobalVariable());
-
-  DIScope GVContext = GV.getContext();
-  DIType GTy = DD->resolve(GV.getType());
-
-  // If this is a static data member definition, some attributes belong
-  // to the declaration DIE.
-  DIE *VariableDIE = nullptr;
-  bool IsStaticMember = false;
-  DIDerivedType SDMDecl = GV.getStaticDataMemberDeclaration();
-  if (SDMDecl.Verify()) {
-    assert(SDMDecl.isStaticMember() && "Expected static member decl");
-    // We need the declaration DIE that is in the static member's class.
-    VariableDIE = getOrCreateStaticMemberDIE(SDMDecl);
-    IsStaticMember = true;
-  }
-
-  // If this is not a static data member definition, create the variable
-  // DIE and add the initial set of attributes to it.
-  if (!VariableDIE) {
-    // Construct the context before querying for the existence of the DIE in
-    // case such construction creates the DIE.
-    DIE *ContextDIE = getOrCreateContextDIE(GVContext);
-
-    // Add to map.
-    VariableDIE = &createAndAddDIE(GV.getTag(), *ContextDIE, GV);
-
-    // Add name and type.
-    addString(*VariableDIE, dwarf::DW_AT_name, GV.getDisplayName());
-    addType(*VariableDIE, GTy);
-
-    // Add scoping info.
-    if (!GV.isLocalToUnit())
-      addFlag(*VariableDIE, dwarf::DW_AT_external);
-
-    // Add line number info.
-    addSourceLine(*VariableDIE, GV);
-  }
-
-  // Add location.
-  bool addToAccelTable = false;
-  DIE *VariableSpecDIE = nullptr;
-  bool isGlobalVariable = GV.getGlobal() != nullptr;
-  if (isGlobalVariable) {
-    addToAccelTable = true;
-    DIELoc *Loc = new (DIEValueAllocator) DIELoc();
-    const MCSymbol *Sym = Asm->getSymbol(GV.getGlobal());
-    if (GV.getGlobal()->isThreadLocal()) {
-      // FIXME: Make this work with -gsplit-dwarf.
-      unsigned PointerSize = Asm->getDataLayout().getPointerSize();
-      assert((PointerSize == 4 || PointerSize == 8) &&
-             "Add support for other sizes if necessary");
-      // Based on GCC's support for TLS:
-      if (!DD->useSplitDwarf()) {
-        // 1) Start with a constNu of the appropriate pointer size
-        addUInt(*Loc, dwarf::DW_FORM_data1,
-                PointerSize == 4 ? dwarf::DW_OP_const4u : dwarf::DW_OP_const8u);
-        // 2) containing the (relocated) offset of the TLS variable
-        //    within the module's TLS block.
-        addExpr(*Loc, dwarf::DW_FORM_udata,
-                Asm->getObjFileLowering().getDebugThreadLocalSymbol(Sym));
-      } else {
-        addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_const_index);
-        addUInt(*Loc, dwarf::DW_FORM_udata,
-                DD->getAddressPool().getIndex(Sym, /* TLS */ true));
-      }
-      // 3) followed by a custom OP to make the debugger do a TLS lookup.
-      addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_GNU_push_tls_address);
-    } else {
-      DD->addArangeLabel(SymbolCU(this, Sym));
-      addOpAddress(*Loc, Sym);
-    }
-    // Do not create specification DIE if context is either compile unit
-    // or a subprogram.
-    if (GVContext && GV.isDefinition() && !GVContext.isCompileUnit() &&
-        !GVContext.isFile() && !DD->isSubprogramContext(GVContext)) {
-      // Create specification DIE.
-      VariableSpecDIE = &createAndAddDIE(dwarf::DW_TAG_variable, UnitDie);
-      addDIEEntry(*VariableSpecDIE, dwarf::DW_AT_specification, *VariableDIE);
-      addBlock(*VariableSpecDIE, dwarf::DW_AT_location, Loc);
-      // A static member's declaration is already flagged as such.
-      if (!SDMDecl.Verify())
-        addFlag(*VariableDIE, dwarf::DW_AT_declaration);
-    } else {
-      addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
-    }
-    // Add the linkage name.
-    StringRef LinkageName = GV.getLinkageName();
-    if (!LinkageName.empty())
-      // From DWARF4: DIEs to which DW_AT_linkage_name may apply include:
-      // TAG_common_block, TAG_constant, TAG_entry_point, TAG_subprogram and
-      // TAG_variable.
-      addString(IsStaticMember && VariableSpecDIE ? *VariableSpecDIE
-                                                  : *VariableDIE,
-                DD->getDwarfVersion() >= 4 ? dwarf::DW_AT_linkage_name
-                                           : dwarf::DW_AT_MIPS_linkage_name,
-                GlobalValue::getRealLinkageName(LinkageName));
-  } else if (const ConstantInt *CI =
-                 dyn_cast_or_null<ConstantInt>(GV.getConstant())) {
-    // AT_const_value was added when the static member was created. To avoid
-    // emitting AT_const_value multiple times, we only add AT_const_value when
-    // it is not a static member.
-    if (!IsStaticMember)
-      addConstantValue(*VariableDIE, CI, GTy);
-  } else if (const ConstantExpr *CE = getMergedGlobalExpr(GV->getOperand(11))) {
-    addToAccelTable = true;
-    // GV is a merged global.
-    DIELoc *Loc = new (DIEValueAllocator) DIELoc();
-    Value *Ptr = CE->getOperand(0);
-    MCSymbol *Sym = Asm->getSymbol(cast<GlobalValue>(Ptr));
-    DD->addArangeLabel(SymbolCU(this, Sym));
-    addOpAddress(*Loc, Sym);
-    addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
-    SmallVector<Value *, 3> Idx(CE->op_begin() + 1, CE->op_end());
-    addUInt(*Loc, dwarf::DW_FORM_udata,
-            Asm->getDataLayout().getIndexedOffset(Ptr->getType(), Idx));
-    addUInt(*Loc, dwarf::DW_FORM_data1, dwarf::DW_OP_plus);
-    addBlock(*VariableDIE, dwarf::DW_AT_location, Loc);
-  }
-
-  if (addToAccelTable) {
-    DIE &AddrDIE = VariableSpecDIE ? *VariableSpecDIE : *VariableDIE;
-    DD->addAccelName(GV.getName(), AddrDIE);
-
-    // If the linkage name is different than the name, go ahead and output
-    // that as well into the name table.
-    if (GV.getLinkageName() != "" && GV.getName() != GV.getLinkageName())
-      DD->addAccelName(GV.getLinkageName(), AddrDIE);
-  }
-
-  addGlobalName(GV.getName(), VariableSpecDIE ? *VariableSpecDIE : *VariableDIE,
-                GV.getContext());
-}
-
 /// constructSubrangeDIE - Construct subrange DIE from DISubrange.
 void DwarfUnit::constructSubrangeDIE(DIE &Buffer, DISubrange SR, DIE *IndexTy) {
   DIE &DW_Subrange = createAndAddDIE(dwarf::DW_TAG_subrange_type, Buffer);
@@ -1700,9 +1391,7 @@
   // The LowerBound value defines the lower bounds which is typically zero for
   // C/C++. The Count value is the number of elements.  Values are 64 bit. If
   // Count == -1 then the array is unbounded and we do not emit
-  // DW_AT_lower_bound and DW_AT_upper_bound attributes. If LowerBound == 0 and
-  // Count == 0, then the array has zero elements in which case we do not emit
-  // an upper bound.
+  // DW_AT_lower_bound and DW_AT_count attributes.
   int64_t LowerBound = SR.getLo();
   int64_t DefaultLowerBound = getDefaultLowerBound();
   int64_t Count = SR.getCount();
@@ -1710,11 +1399,22 @@
   if (DefaultLowerBound == -1 || LowerBound != DefaultLowerBound)
     addUInt(DW_Subrange, dwarf::DW_AT_lower_bound, None, LowerBound);
 
-  if (Count != -1 && Count != 0)
+  if (Count != -1)
     // FIXME: An unbounded array should reference the expression that defines
     // the array.
-    addUInt(DW_Subrange, dwarf::DW_AT_upper_bound, None,
-            LowerBound + Count - 1);
+    addUInt(DW_Subrange, dwarf::DW_AT_count, None, Count);
+}
+
+DIE *DwarfUnit::getIndexTyDie() {
+  if (IndexTyDie)
+    return IndexTyDie;
+  // Construct an integer type to use for indexes.
+  IndexTyDie = &createAndAddDIE(dwarf::DW_TAG_base_type, UnitDie);
+  addString(*IndexTyDie, dwarf::DW_AT_name, "sizetype");
+  addUInt(*IndexTyDie, dwarf::DW_AT_byte_size, None, sizeof(int64_t));
+  addUInt(*IndexTyDie, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1,
+          dwarf::DW_ATE_unsigned);
+  return IndexTyDie;
 }
 
 /// constructArrayTypeDIE - Construct array type DIE from DICompositeType.
@@ -1729,18 +1429,9 @@
   // FIXME: This type should be passed down from the front end
   // as different languages may have different sizes for indexes.
   DIE *IdxTy = getIndexTyDie();
-  if (!IdxTy) {
-    // Construct an integer type to use for indexes.
-    IdxTy = &createAndAddDIE(dwarf::DW_TAG_base_type, UnitDie);
-    addString(*IdxTy, dwarf::DW_AT_name, "sizetype");
-    addUInt(*IdxTy, dwarf::DW_AT_byte_size, None, sizeof(int64_t));
-    addUInt(*IdxTy, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1,
-            dwarf::DW_ATE_unsigned);
-    setIndexTyDie(IdxTy);
-  }
 
   // Add subranges to array type.
-  DIArray Elements = CTy.getTypeArray();
+  DIArray Elements = CTy.getElements();
   for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
     DIDescriptor Element = Elements.getElement(i);
     if (Element.getTag() == dwarf::DW_TAG_subrange_type)
@@ -1750,7 +1441,7 @@
 
 /// constructEnumTypeDIE - Construct an enum type DIE from DICompositeType.
 void DwarfUnit::constructEnumTypeDIE(DIE &Buffer, DICompositeType CTy) {
-  DIArray Elements = CTy.getTypeArray();
+  DIArray Elements = CTy.getElements();
 
   // Add enumerators to enumeration type.
   for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
@@ -1788,68 +1479,6 @@
   }
 }
 
-/// constructVariableDIE - Construct a DIE for the given DbgVariable.
-std::unique_ptr<DIE> DwarfUnit::constructVariableDIE(DbgVariable &DV,
-                                                     bool Abstract) {
-  auto D = constructVariableDIEImpl(DV, Abstract);
-  DV.setDIE(*D);
-  return D;
-}
-
-std::unique_ptr<DIE> DwarfUnit::constructVariableDIEImpl(const DbgVariable &DV,
-                                                         bool Abstract) {
-  // Define variable debug information entry.
-  auto VariableDie = make_unique<DIE>(DV.getTag());
-
-  if (Abstract) {
-    applyVariableAttributes(DV, *VariableDie);
-    return VariableDie;
-  }
-
-  // Add variable address.
-
-  unsigned Offset = DV.getDotDebugLocOffset();
-  if (Offset != ~0U) {
-    addLocationList(*VariableDie, dwarf::DW_AT_location, Offset);
-    return VariableDie;
-  }
-
-  // Check if variable is described by a DBG_VALUE instruction.
-  if (const MachineInstr *DVInsn = DV.getMInsn()) {
-    assert(DVInsn->getNumOperands() == 3);
-    if (DVInsn->getOperand(0).isReg()) {
-      const MachineOperand RegOp = DVInsn->getOperand(0);
-      // If the second operand is an immediate, this is an indirect value.
-      if (DVInsn->getOperand(1).isImm()) {
-        MachineLocation Location(RegOp.getReg(),
-                                 DVInsn->getOperand(1).getImm());
-        addVariableAddress(DV, *VariableDie, Location);
-      } else if (RegOp.getReg())
-        addVariableAddress(DV, *VariableDie, MachineLocation(RegOp.getReg()));
-    } else if (DVInsn->getOperand(0).isImm())
-      addConstantValue(*VariableDie, DVInsn->getOperand(0), DV.getType());
-    else if (DVInsn->getOperand(0).isFPImm())
-      addConstantFPValue(*VariableDie, DVInsn->getOperand(0));
-    else if (DVInsn->getOperand(0).isCImm())
-      addConstantValue(*VariableDie, DVInsn->getOperand(0).getCImm(),
-                       DV.getType());
-
-    return VariableDie;
-  }
-
-  // .. else use frame index.
-  int FI = DV.getFrameIndex();
-  if (FI != ~0) {
-    unsigned FrameReg = 0;
-    const TargetFrameLowering *TFI = Asm->TM.getFrameLowering();
-    int Offset = TFI->getFrameIndexReference(*Asm->MF, FI, FrameReg);
-    MachineLocation Location(FrameReg, Offset);
-    addVariableAddress(DV, *VariableDie, Location);
-  }
-
-  return VariableDie;
-}
-
 /// constructMemberDIE - Construct member DIE from DIDerivedType.
 void DwarfUnit::constructMemberDIE(DIE &Buffer, DIDerivedType DT) {
   DIE &MemberDie = createAndAddDIE(DT.getTag(), Buffer);
@@ -1922,7 +1551,7 @@
     addUInt(MemberDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_data1,
             dwarf::DW_ACCESS_private);
   // Otherwise C++ member and base classes are considered public.
-  else
+  else if (DT.isPublic())
     addUInt(MemberDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_data1,
             dwarf::DW_ACCESS_public);
   if (DT.isVirtual())
@@ -1971,7 +1600,7 @@
   else if (DT.isPrivate())
     addUInt(StaticMemberDIE, dwarf::DW_AT_accessibility, dwarf::DW_FORM_data1,
             dwarf::DW_ACCESS_private);
-  else
+  else if (DT.isPublic())
     addUInt(StaticMemberDIE, dwarf::DW_AT_accessibility, dwarf::DW_FORM_data1,
             dwarf::DW_ACCESS_public);
 
@@ -1984,6 +1613,10 @@
 }
 
 void DwarfUnit::emitHeader(const MCSymbol *ASectionSym) const {
+  // Emit size of content not including length itself
+  Asm->OutStreamer.AddComment("Length of Unit");
+  Asm->EmitInt32(getHeaderSize() + UnitDie.getSize());
+
   Asm->OutStreamer.AddComment("DWARF version number");
   Asm->EmitInt16(DD->getDwarfVersion());
   Asm->OutStreamer.AddComment("Offset Into Abbrev. Section");
@@ -1999,50 +1632,9 @@
   Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
 }
 
-void DwarfUnit::addRange(RangeSpan Range) {
-  // Only add a range for this unit if we're emitting full debug.
-  if (getCUNode().getEmissionKind() == DIBuilder::FullDebug) {
-    // If we have no current ranges just add the range and return, otherwise,
-    // check the current section and CU against the previous section and CU we
-    // emitted into and the subprogram was contained within. If these are the
-    // same then extend our current range, otherwise add this as a new range.
-    if (CURanges.size() == 0 ||
-        this != DD->getPrevCU() ||
-        Asm->getCurrentSection() != DD->getPrevSection()) {
-      CURanges.push_back(Range);
-      return;
-    }
-
-    assert(&(CURanges.back().getEnd()->getSection()) ==
-               &(Range.getEnd()->getSection()) &&
-           "We can only append to a range in the same section!");
-    CURanges.back().setEnd(Range.getEnd());
-  }
-}
-
-void DwarfCompileUnit::initStmtList(MCSymbol *DwarfLineSectionSym) {
-  // Define start line table label for each Compile Unit.
-  MCSymbol *LineTableStartSym =
-      Asm->OutStreamer.getDwarfLineTableSymbol(getUniqueID());
-
-  stmtListIndex = UnitDie.getValues().size();
-
-  // 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())
-    addSectionLabel(UnitDie, dwarf::DW_AT_stmt_list, LineTableStartSym);
-  else
-    addSectionDelta(UnitDie, dwarf::DW_AT_stmt_list, LineTableStartSym,
-                    DwarfLineSectionSym);
-}
-
-void DwarfCompileUnit::applyStmtList(DIE &D) {
-  D.addValue(dwarf::DW_AT_stmt_list,
-             UnitDie.getAbbrev().getData()[stmtListIndex].getForm(),
-             UnitDie.getValues()[stmtListIndex]);
+void DwarfUnit::initSection(const MCSection *Section) {
+  assert(!this->Section);
+  this->Section = Section;
 }
 
 void DwarfTypeUnit::emitHeader(const MCSymbol *ASectionSym) const {
@@ -2055,16 +1647,8 @@
                                 sizeof(Ty->getOffset()));
 }
 
-void DwarfTypeUnit::initSection(const MCSection *Section) {
-  assert(!this->Section);
-  this->Section = Section;
-  // Since each type unit is contained in its own COMDAT section, the begin
-  // label and the section label are the same. Using the begin label emission in
-  // DwarfDebug to emit the section label as well is slightly subtle/sneaky, but
-  // the only other alternative of lazily constructing start-of-section labels
-  // and storing a mapping in DwarfDebug (or AsmPrinter).
-  this->SectionSym = this->LabelBegin =
-      Asm->GetTempSymbol(Section->getLabelBeginName(), getUniqueID());
-  this->LabelEnd =
-      Asm->GetTempSymbol(Section->getLabelEndName(), getUniqueID());
+bool DwarfTypeUnit::isDwoUnit() const {
+  // Since there are no skeleton type units, all type units are dwo type units
+  // when split DWARF is being used.
+  return DD->useSplitDwarf();
 }
diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.h b/lib/CodeGen/AsmPrinter/DwarfUnit.h
index b7b83b2..f40c937 100644
--- a/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -11,8 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
-#define CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFUNIT_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFUNIT_H
 
 #include "DIE.h"
 #include "DwarfDebug.h"
@@ -55,7 +55,8 @@
   SmallVector<RangeSpan, 2> Ranges;
 
 public:
-  RangeSpanList(MCSymbol *Sym) : RangeSym(Sym) {}
+  RangeSpanList(MCSymbol *Sym, SmallVector<RangeSpan, 2> Ranges)
+      : RangeSym(Sym), Ranges(std::move(Ranges)) {}
   MCSymbol *getSym() const { return RangeSym; }
   const SmallVectorImpl<RangeSpan> &getRanges() const { return Ranges; }
   void addRange(RangeSpan Range) { Ranges.push_back(Range); }
@@ -96,12 +97,6 @@
   /// descriptors to debug information entries using a DIEEntry proxy.
   DenseMap<const MDNode *, DIEEntry *> MDNodeToDIEEntryMap;
 
-  /// GlobalNames - A map of globally visible named entities for this unit.
-  StringMap<const DIE *> GlobalNames;
-
-  /// GlobalTypes - A map of globally visible types for this unit.
-  StringMap<const DIE *> GlobalTypes;
-
   /// DIEBlocks - A list of all the DIEBlocks in use.
   std::vector<DIEBlock *> DIEBlocks;
   
@@ -113,13 +108,6 @@
   /// corresponds to the MDNode mapped with the subprogram DIE.
   DenseMap<DIE *, const MDNode *> ContainingTypeMap;
 
-  // List of ranges for a given compile unit.
-  SmallVector<RangeSpan, 1> CURanges;
-
-  // List of range lists for a given compile unit, separate from the ranges for
-  // the CU itself.
-  SmallVector<RangeSpanList, 1> CURangeLists;
-
   // DIEValueAllocator - All DIEValues are allocated through this allocator.
   BumpPtrAllocator DIEValueAllocator;
 
@@ -129,86 +117,31 @@
   /// The section this unit will be emitted in.
   const MCSection *Section;
 
-  /// A label at the start of the non-dwo section related to this unit.
-  MCSymbol *SectionSym;
-
-  /// The start of the unit within its section.
-  MCSymbol *LabelBegin;
-
-  /// The end of the unit within its section.
-  MCSymbol *LabelEnd;
-
-  /// Skeleton unit associated with this unit.
-  DwarfUnit *Skeleton;
-
   DwarfUnit(unsigned UID, dwarf::Tag, DICompileUnit CU, AsmPrinter *A,
             DwarfDebug *DW, DwarfFile *DWU);
 
+  void initSection(const MCSection *Section);
+
+  /// Add a string attribute data and value.
+  void addLocalString(DIE &Die, dwarf::Attribute Attribute, StringRef Str);
+
+  void addIndexedString(DIE &Die, dwarf::Attribute Attribute, StringRef Str);
+
+  bool applySubprogramDefinitionAttributes(DISubprogram SP, DIE &SPDie);
+
 public:
   virtual ~DwarfUnit();
 
-  /// Set the skeleton unit associated with this unit.
-  void setSkeleton(DwarfUnit &Skel) { Skeleton = &Skel; }
-
-  /// Get the skeleton unit associated with this unit.
-  DwarfUnit *getSkeleton() const { return Skeleton; }
-
-  /// Pass in the SectionSym even though we could recreate it in every compile
-  /// unit (type units will have actually distinct symbols once they're in
-  /// comdat sections).
-  void initSection(const MCSection *Section, MCSymbol *SectionSym) {
-    assert(!this->Section);
-    this->Section = Section;
-    this->SectionSym = SectionSym;
-    this->LabelBegin =
-        Asm->GetTempSymbol(Section->getLabelBeginName(), getUniqueID());
-    this->LabelEnd =
-        Asm->GetTempSymbol(Section->getLabelEndName(), getUniqueID());
-  }
-
   const MCSection *getSection() const {
     assert(Section);
     return Section;
   }
 
-  /// If there's a skeleton then return the section symbol for the skeleton
-  /// unit, otherwise return the section symbol for this unit.
-  MCSymbol *getLocalSectionSym() const {
-    if (Skeleton)
-      return Skeleton->getSectionSym();
-    return getSectionSym();
-  }
-
-  MCSymbol *getSectionSym() const {
-    assert(Section);
-    return SectionSym;
-  }
-
-  /// If there's a skeleton then return the begin label for the skeleton unit,
-  /// otherwise return the local label for this unit.
-  MCSymbol *getLocalLabelBegin() const {
-    if (Skeleton)
-      return Skeleton->getLabelBegin();
-    return getLabelBegin();
-  }
-
-  MCSymbol *getLabelBegin() const {
-    assert(Section);
-    return LabelBegin;
-  }
-
-  MCSymbol *getLabelEnd() const {
-    assert(Section);
-    return LabelEnd;
-  }
-
   // Accessors.
   unsigned getUniqueID() const { return UniqueID; }
   uint16_t getLanguage() const { return CUNode.getLanguage(); }
   DICompileUnit getCUNode() const { return CUNode; }
   DIE &getUnitDie() { return UnitDie; }
-  const StringMap<const DIE *> &getGlobalNames() const { return GlobalNames; }
-  const StringMap<const DIE *> &getGlobalTypes() const { return GlobalTypes; }
 
   unsigned getDebugInfoOffset() const { return DebugInfoOffset; }
   void setDebugInfoOffset(unsigned DbgInfoOff) { DebugInfoOffset = DbgInfoOff; }
@@ -216,29 +149,15 @@
   /// hasContent - Return true if this compile unit has something to write out.
   bool hasContent() const { return !UnitDie.getChildren().empty(); }
 
-  /// addRange - Add an address range to the list of ranges for this unit.
-  void addRange(RangeSpan Range);
-
-  /// getRanges - Get the list of ranges for this unit.
-  const SmallVectorImpl<RangeSpan> &getRanges() const { return CURanges; }
-  SmallVectorImpl<RangeSpan> &getRanges() { return CURanges; }
-
-  /// addRangeList - Add an address range list to the list of range lists.
-  void addRangeList(RangeSpanList Ranges) { CURangeLists.push_back(Ranges); }
-
-  /// getRangeLists - Get the vector of range lists.
-  const SmallVectorImpl<RangeSpanList> &getRangeLists() const {
-    return CURangeLists;
-  }
-  SmallVectorImpl<RangeSpanList> &getRangeLists() { return CURangeLists; }
-
   /// getParentContextString - Get a string containing the language specific
   /// context for a global name.
   std::string getParentContextString(DIScope Context) const;
 
-  /// addGlobalName - Add a new global entity to the compile unit.
-  ///
-  void addGlobalName(StringRef Name, DIE &Die, DIScope Context);
+  /// Add a new global name to the compile unit.
+  virtual void addGlobalName(StringRef Name, DIE &Die, DIScope Context) {}
+
+  /// Add a new global type to the compile unit.
+  virtual void addGlobalType(DIType Ty, const DIE &Die, DIScope Context) {}
 
   /// addAccelNamespace - Add a new name to the namespace accelerator table.
   void addAccelNamespace(StringRef Name, const DIE &Die);
@@ -275,14 +194,7 @@
   void addSInt(DIELoc &Die, Optional<dwarf::Form> Form, int64_t Integer);
 
   /// addString - Add a string attribute data and value.
-  void addString(DIE &Die, dwarf::Attribute Attribute, const StringRef Str);
-
-  /// addLocalString - Add a string attribute data and value.
-  void addLocalString(DIE &Die, dwarf::Attribute Attribute,
-                      const StringRef Str);
-
-  /// addExpr - Add a Dwarf expression attribute data and value.
-  void addExpr(DIELoc &Die, dwarf::Form Form, const MCExpr *Expr);
+  void addString(DIE &Die, dwarf::Attribute Attribute, StringRef Str);
 
   /// addLabel - Add a Dwarf label attribute data and value.
   void addLabel(DIE &Die, dwarf::Attribute Attribute, dwarf::Form Form,
@@ -290,14 +202,6 @@
 
   void addLabel(DIELoc &Die, dwarf::Form Form, const MCSymbol *Label);
 
-  /// addLocationList - Add a Dwarf loclistptr attribute data and value.
-  void addLocationList(DIE &Die, dwarf::Attribute Attribute, unsigned Index);
-
-  /// addSectionLabel - Add a Dwarf section label attribute data and value.
-  ///
-  void addSectionLabel(DIE &Die, dwarf::Attribute Attribute,
-                       const MCSymbol *Label);
-
   /// addSectionOffset - Add an offset into a section attribute data and value.
   ///
   void addSectionOffset(DIE &Die, dwarf::Attribute Attribute, uint64_t Integer);
@@ -306,10 +210,6 @@
   /// form given and an op of either DW_FORM_addr or DW_FORM_GNU_addr_index.
   void addOpAddress(DIELoc &Die, const MCSymbol *Label);
 
-  /// addSectionDelta - Add a label delta attribute data and value.
-  void addSectionDelta(DIE &Die, dwarf::Attribute Attribute, const MCSymbol *Hi,
-                       const MCSymbol *Lo);
-
   /// addLabelDelta - Add a label delta attribute data and value.
   void addLabelDelta(DIE &Die, dwarf::Attribute Attribute, const MCSymbol *Hi,
                      const MCSymbol *Lo);
@@ -339,11 +239,6 @@
   void addSourceLine(DIE &Die, DINameSpace NS);
   void addSourceLine(DIE &Die, DIObjCProperty Ty);
 
-  /// addAddress - Add an address attribute to a die based on the location
-  /// provided.
-  void addAddress(DIE &Die, dwarf::Attribute Attribute,
-                  const MachineLocation &Location, bool Indirect = false);
-
   /// addConstantValue - Add constant value entry in variable DIE.
   void addConstantValue(DIE &Die, const MachineOperand &MO, DIType Ty);
   void addConstantValue(DIE &Die, const ConstantInt *CI, DIType Ty);
@@ -359,19 +254,12 @@
   void addTemplateParams(DIE &Buffer, DIArray TParams);
 
   /// addRegisterOp - Add register operand.
-  void addRegisterOp(DIELoc &TheDie, unsigned Reg);
+  void addRegisterOpPiece(DIELoc &TheDie, unsigned Reg,
+                          unsigned SizeInBits = 0, unsigned OffsetInBits = 0);
 
   /// addRegisterOffset - Add register offset.
   void addRegisterOffset(DIELoc &TheDie, unsigned Reg, int64_t Offset);
 
-  /// addComplexAddress - Start with the address based on the location provided,
-  /// and generate the DWARF information necessary to find the actual variable
-  /// (navigating the extra location information encoded in the type) based on
-  /// the starting location.  Add the DWARF information to the die.
-  void addComplexAddress(const DbgVariable &DV, DIE &Die,
-                         dwarf::Attribute Attribute,
-                         const MachineLocation &Location);
-
   // FIXME: Should be reformulated in terms of addComplexAddress.
   /// addBlockByrefAddress - Start with the address based on the location
   /// provided, and generate the DWARF information necessary to find the
@@ -382,11 +270,6 @@
                             dwarf::Attribute Attribute,
                             const MachineLocation &Location);
 
-  /// addVariableAddress - Add DW_AT_location attribute for a
-  /// DbgVariable based on provided MachineLocation.
-  void addVariableAddress(const DbgVariable &DV, DIE &Die,
-                          MachineLocation Location);
-
   /// addType - Add a new type attribute to the specified entity. This takes
   /// and attribute parameter because DW_AT_friend attributes are also
   /// type references.
@@ -397,11 +280,10 @@
   DIE *getOrCreateNameSpace(DINameSpace NS);
 
   /// getOrCreateSubprogramDIE - Create new DIE using SP.
-  DIE *getOrCreateSubprogramDIE(DISubprogram SP);
+  DIE *getOrCreateSubprogramDIE(DISubprogram SP, bool Minimal = false);
 
-  void applySubprogramAttributes(DISubprogram SP, DIE &SPDie);
-  void applySubprogramAttributesToDefinition(DISubprogram SP, DIE &SPDie);
-  void applyVariableAttributes(const DbgVariable &Var, DIE &VariableDie);
+  void applySubprogramAttributes(DISubprogram SP, DIE &SPDie,
+                                 bool Minimal = false);
 
   /// getOrCreateTypeDIE - Find existing DIE or create new DIE for the
   /// given DIType.
@@ -417,12 +299,8 @@
   /// vtables.
   void constructContainingTypeDIEs();
 
-  /// constructVariableDIE - Construct a DIE for the given DbgVariable.
-  std::unique_ptr<DIE> constructVariableDIE(DbgVariable &DV,
-                                            bool Abstract = false);
-
   /// constructSubprogramArguments - Construct function argument DIEs.
-  void constructSubprogramArguments(DIE &Buffer, DIArray Args);
+  void constructSubprogramArguments(DIE &Buffer, DITypeArray Args);
 
   /// Create a DIE with the given Tag, add the DIE to its parent, and
   /// call insertDIE if MD is not null.
@@ -453,12 +331,13 @@
   /// none currently exists, create a new ID and insert it in the line table.
   virtual unsigned getOrCreateSourceID(StringRef File, StringRef Directory) = 0;
 
-private:
-  /// \brief Construct a DIE for the given DbgVariable without initializing the
-  /// DbgVariable's DIE reference.
-  std::unique_ptr<DIE> constructVariableDIEImpl(const DbgVariable &DV,
-                                                bool Abstract);
+  /// resolve - Look in the DwarfDebug map for the MDNode that
+  /// corresponds to the reference.
+  template <typename T> T resolve(DIRef<T> Ref) const {
+    return DD->resolve(Ref);
+  }
 
+private:
   /// constructTypeDIE - Construct basic type die from DIBasicType.
   void constructTypeDIE(DIE &Buffer, DIBasicType BTy);
 
@@ -503,7 +382,7 @@
   }
 
   // getIndexTyDie - Get an anonymous type for index type.
-  DIE *getIndexTyDie() { return IndexTyDie; }
+  DIE *getIndexTyDie();
 
   // setIndexTyDie - Set D as anonymous type for index which can be reused
   // later.
@@ -513,56 +392,22 @@
   /// information entry.
   DIEEntry *createDIEEntry(DIE &Entry);
 
-  /// resolve - Look in the DwarfDebug map for the MDNode that
-  /// corresponds to the reference.
-  template <typename T> T resolve(DIRef<T> Ref) const {
-    return DD->resolve(Ref);
-  }
-
   /// If this is a named finished type then include it in the list of types for
   /// the accelerator tables.
   void updateAcceleratorTables(DIScope Context, DIType Ty, const DIE &TyDIE);
-};
 
-class DwarfCompileUnit : public DwarfUnit {
-  /// The attribute index of DW_AT_stmt_list in the compile unit DIE, avoiding
-  /// the need to search for it in applyStmtList.
-  unsigned stmtListIndex;
-
-public:
-  DwarfCompileUnit(unsigned UID, DICompileUnit Node, AsmPrinter *A,
-                   DwarfDebug *DW, DwarfFile *DWU);
-
-  void initStmtList(MCSymbol *DwarfLineSectionSym);
-
-  /// Apply the DW_AT_stmt_list from this compile unit to the specified DIE.
-  void applyStmtList(DIE &D);
-
-  /// createGlobalVariableDIE - create global variable DIE.
-  void createGlobalVariableDIE(DIGlobalVariable GV);
-
-  /// addLabelAddress - Add a dwarf label attribute data and value using
-  /// either DW_FORM_addr or DW_FORM_GNU_addr_index.
-  void addLabelAddress(DIE &Die, dwarf::Attribute Attribute,
-                       const MCSymbol *Label);
-
-  /// addLocalLabelAddress - Add a dwarf label attribute data and value using
-  /// DW_FORM_addr only.
-  void addLocalLabelAddress(DIE &Die, dwarf::Attribute Attribute,
-                            const MCSymbol *Label);
-
-  DwarfCompileUnit &getCU() override { return *this; }
-
-  unsigned getOrCreateSourceID(StringRef FileName, StringRef DirName) override;
+  virtual bool isDwoUnit() const = 0;
 };
 
 class DwarfTypeUnit : public DwarfUnit {
-private:
   uint64_t TypeSignature;
   const DIE *Ty;
   DwarfCompileUnit &CU;
   MCDwarfDwoLineTable *SplitLineTable;
 
+  unsigned getOrCreateSourceID(StringRef File, StringRef Directory) override;
+  bool isDwoUnit() const override;
+
 public:
   DwarfTypeUnit(unsigned UID, DwarfCompileUnit &CU, AsmPrinter *A,
                 DwarfDebug *DW, DwarfFile *DWU,
@@ -578,11 +423,8 @@
     return DwarfUnit::getHeaderSize() + sizeof(uint64_t) + // Type Signature
            sizeof(uint32_t);                               // Type DIE Offset
   }
-  void initSection(const MCSection *Section);
+  using DwarfUnit::initSection;
   DwarfCompileUnit &getCU() override { return CU; }
-
-protected:
-  unsigned getOrCreateSourceID(StringRef File, StringRef Directory) override;
 };
 } // end llvm namespace
 #endif
diff --git a/lib/CodeGen/AsmPrinter/EHStreamer.cpp b/lib/CodeGen/AsmPrinter/EHStreamer.cpp
index 73f62bf..2bbffb3 100644
--- a/lib/CodeGen/AsmPrinter/EHStreamer.cpp
+++ b/lib/CodeGen/AsmPrinter/EHStreamer.cpp
@@ -237,7 +237,7 @@
       // instruction between the previous try-range and this one may throw,
       // create a call-site entry with no landing pad for the region between the
       // try-ranges.
-      if (SawPotentiallyThrowing && Asm->MAI->isExceptionHandlingDwarf()) {
+      if (SawPotentiallyThrowing && Asm->MAI->usesItaniumLSDAForExceptions()) {
         CallSiteEntry Site = { LastLabel, BeginLabel, nullptr, 0 };
         CallSites.push_back(Site);
         PreviousIsInvoke = false;
@@ -259,7 +259,7 @@
         };
 
         // Try to merge with the previous call-site. SJLJ doesn't do this
-        if (PreviousIsInvoke && Asm->MAI->isExceptionHandlingDwarf()) {
+        if (PreviousIsInvoke && Asm->MAI->usesItaniumLSDAForExceptions()) {
           CallSiteEntry &Prev = CallSites.back();
           if (Site.PadLabel == Prev.PadLabel && Site.Action == Prev.Action) {
             // Extend the range of the previous entry.
@@ -269,7 +269,7 @@
         }
 
         // Otherwise, create a new call-site.
-        if (Asm->MAI->isExceptionHandlingDwarf())
+        if (Asm->MAI->usesItaniumLSDAForExceptions())
           CallSites.push_back(Site);
         else {
           // SjLj EH must maintain the call sites in the order assigned
@@ -287,7 +287,7 @@
   // If some instruction between the previous try-range and the end of the
   // function may throw, create a call-site entry with no landing pad for the
   // region following the try-range.
-  if (SawPotentiallyThrowing && Asm->MAI->isExceptionHandlingDwarf()) {
+  if (SawPotentiallyThrowing && Asm->MAI->usesItaniumLSDAForExceptions()) {
     CallSiteEntry Site = { LastLabel, nullptr, nullptr, 0 };
     CallSites.push_back(Site);
   }
@@ -314,7 +314,7 @@
 ///  3. Type ID table contains references to all the C++ typeinfo for all
 ///     catches in the function.  This tables is reverse indexed base 1.
 void EHStreamer::emitExceptionTable() {
-  const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
+  const std::vector<const GlobalValue *> &TypeInfos = MMI->getTypeInfos();
   const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
   const std::vector<LandingPadInfo> &PadInfos = MMI->getLandingPads();
 
@@ -520,7 +520,7 @@
     }
   } else {
     // DWARF Exception handling
-    assert(Asm->MAI->isExceptionHandlingDwarf());
+    assert(Asm->MAI->usesItaniumLSDAForExceptions());
 
     // The call-site table is a list of all call sites that may throw an
     // exception (including C++ 'throw' statements) in the procedure
@@ -649,7 +649,7 @@
 }
 
 void EHStreamer::emitTypeInfos(unsigned TTypeEncoding) {
-  const std::vector<const GlobalVariable *> &TypeInfos = MMI->getTypeInfos();
+  const std::vector<const GlobalValue *> &TypeInfos = MMI->getTypeInfos();
   const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
 
   bool VerboseAsm = Asm->OutStreamer.isVerboseAsm();
@@ -662,9 +662,9 @@
     Entry = TypeInfos.size();
   }
 
-  for (std::vector<const GlobalVariable *>::const_reverse_iterator
+  for (std::vector<const GlobalValue *>::const_reverse_iterator
          I = TypeInfos.rbegin(), E = TypeInfos.rend(); I != E; ++I) {
-    const GlobalVariable *GV = *I;
+    const GlobalValue *GV = *I;
     if (VerboseAsm)
       Asm->OutStreamer.AddComment("TypeInfo " + Twine(Entry--));
     Asm->EmitTTypeReference(GV, TTypeEncoding);
diff --git a/lib/CodeGen/AsmPrinter/EHStreamer.h b/lib/CodeGen/AsmPrinter/EHStreamer.h
index 2b6ba78..7e9549d 100644
--- a/lib/CodeGen/AsmPrinter/EHStreamer.h
+++ b/lib/CodeGen/AsmPrinter/EHStreamer.h
@@ -11,8 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_CODEGEN_ASMPRINTER_EHSTREAMER_H
-#define LLVM_CODEGEN_ASMPRINTER_EHSTREAMER_H
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_EHSTREAMER_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_EHSTREAMER_H
 
 #include "AsmPrinterHandler.h"
 #include "llvm/ADT/DenseMap.h"
diff --git a/lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp b/lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp
index bfcbe6b..5bda5a9 100644
--- a/lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp
@@ -28,6 +28,7 @@
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Target/TargetLoweringObjectFile.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
 
 using namespace llvm;
 
@@ -50,7 +51,8 @@
 
 void ErlangGCPrinter::finishAssembly(AsmPrinter &AP) {
   MCStreamer &OS = AP.OutStreamer;
-  unsigned IntPtrSize = AP.TM.getDataLayout()->getPointerSize();
+  unsigned IntPtrSize =
+      AP.TM.getSubtargetImpl()->getDataLayout()->getPointerSize();
 
   // Put this in a custom .note section.
   AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getContext()
diff --git a/lib/CodeGen/AsmPrinter/OcamlGCPrinter.cpp b/lib/CodeGen/AsmPrinter/OcamlGCPrinter.cpp
index 5a9ecd7..6480d048 100644
--- a/lib/CodeGen/AsmPrinter/OcamlGCPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/OcamlGCPrinter.cpp
@@ -26,6 +26,7 @@
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Target/TargetLoweringObjectFile.h"
 #include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
 #include <cctype>
 using namespace llvm;
 
@@ -91,7 +92,8 @@
 /// either condition is detected in a function which uses the GC.
 ///
 void OcamlGCMetadataPrinter::finishAssembly(AsmPrinter &AP) {
-  unsigned IntPtrSize = AP.TM.getDataLayout()->getPointerSize();
+  unsigned IntPtrSize =
+      AP.TM.getSubtargetImpl()->getDataLayout()->getPointerSize();
 
   AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getTextSection());
   EmitCamlGlobal(getModule(), AP, "code_end");
diff --git a/lib/CodeGen/AsmPrinter/Win64Exception.cpp b/lib/CodeGen/AsmPrinter/Win64Exception.cpp
index 81285d5..0f0ad75 100644
--- a/lib/CodeGen/AsmPrinter/Win64Exception.cpp
+++ b/lib/CodeGen/AsmPrinter/Win64Exception.cpp
@@ -11,7 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "DwarfException.h"
+#include "Win64Exception.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/Twine.h"
diff --git a/lib/CodeGen/AsmPrinter/Win64Exception.h b/lib/CodeGen/AsmPrinter/Win64Exception.h
new file mode 100644
index 0000000..538e132
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/Win64Exception.h
@@ -0,0 +1,52 @@
+//===-- Win64Exception.h - Windows Exception Handling ----------*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing windows exception info into asm files.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_WIN64EXCEPTION_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_WIN64EXCEPTION_H
+
+#include "EHStreamer.h"
+
+namespace llvm {
+class MachineFunction;
+
+class Win64Exception : public EHStreamer {
+  /// Per-function flag to indicate if personality info should be emitted.
+  bool shouldEmitPersonality;
+
+  /// Per-function flag to indicate if the LSDA should be emitted.
+  bool shouldEmitLSDA;
+
+  /// Per-function flag to indicate if frame moves info should be emitted.
+  bool shouldEmitMoves;
+
+public:
+  //===--------------------------------------------------------------------===//
+  // Main entry points.
+  //
+  Win64Exception(AsmPrinter *A);
+  virtual ~Win64Exception();
+
+  /// Emit all exception information that should come after the content.
+  void endModule() override;
+
+  /// Gather pre-function exception information.  Assumes being emitted
+  /// immediately after the function entry point.
+  void beginFunction(const MachineFunction *MF) override;
+
+  /// Gather and emit post-function exception information.
+  void endFunction(const MachineFunction *) override;
+};
+}
+
+#endif
+
diff --git a/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp b/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
index 6a5c431..b5e0929 100644
--- a/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
+++ b/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
@@ -116,15 +116,67 @@
   Asm = AP;
 }
 
+void WinCodeViewLineTables::endModule() {
+  if (FnDebugInfo.empty())
+    return;
+
+  assert(Asm != nullptr);
+  Asm->OutStreamer.SwitchSection(
+      Asm->getObjFileLowering().getCOFFDebugSymbolsSection());
+  Asm->EmitInt32(COFF::DEBUG_SECTION_MAGIC);
+
+  // The COFF .debug$S section consists of several subsections, each starting
+  // with a 4-byte control code (e.g. 0xF1, 0xF2, etc) and then a 4-byte length
+  // of the payload followed by the payload itself.  The subsections are 4-byte
+  // aligned.
+
+  // Emit per-function debug information.  This code is extracted into a
+  // separate function for readability.
+  for (size_t I = 0, E = VisitedFunctions.size(); I != E; ++I)
+    emitDebugInfoForFunction(VisitedFunctions[I]);
+
+  // This subsection holds a file index to offset in string table table.
+  Asm->OutStreamer.AddComment("File index to string table offset subsection");
+  Asm->EmitInt32(COFF::DEBUG_INDEX_SUBSECTION);
+  size_t NumFilenames = FileNameRegistry.Infos.size();
+  Asm->EmitInt32(8 * NumFilenames);
+  for (size_t I = 0, E = FileNameRegistry.Filenames.size(); I != E; ++I) {
+    StringRef Filename = FileNameRegistry.Filenames[I];
+    // For each unique filename, just write its offset in the string table.
+    Asm->EmitInt32(FileNameRegistry.Infos[Filename].StartOffset);
+    // The function name offset is not followed by any additional data.
+    Asm->EmitInt32(0);
+  }
+
+  // This subsection holds the string table.
+  Asm->OutStreamer.AddComment("String table");
+  Asm->EmitInt32(COFF::DEBUG_STRING_TABLE_SUBSECTION);
+  Asm->EmitInt32(FileNameRegistry.LastOffset);
+  // The payload starts with a null character.
+  Asm->EmitInt8(0);
+
+  for (size_t I = 0, E = FileNameRegistry.Filenames.size(); I != E; ++I) {
+    // Just emit unique filenames one by one, separated by a null character.
+    Asm->OutStreamer.EmitBytes(FileNameRegistry.Filenames[I]);
+    Asm->EmitInt8(0);
+  }
+
+  // No more subsections. Fill with zeros to align the end of the section by 4.
+  Asm->OutStreamer.EmitFill((-FileNameRegistry.LastOffset) % 4, 0);
+
+  clear();
+}
+
 static void EmitLabelDiff(MCStreamer &Streamer,
-                          const MCSymbol *From, const MCSymbol *To) {
+                          const MCSymbol *From, const MCSymbol *To,
+                          unsigned int Size = 4) {
   MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
   MCContext &Context = Streamer.getContext();
   const MCExpr *FromRef = MCSymbolRefExpr::Create(From, Variant, Context),
                *ToRef   = MCSymbolRefExpr::Create(To, Variant, Context);
   const MCExpr *AddrDelta =
       MCBinaryExpr::Create(MCBinaryExpr::Sub, ToRef, FromRef, Context);
-  Streamer.EmitValue(AddrDelta, 4);
+  Streamer.EmitValue(AddrDelta, Size);
 }
 
 void WinCodeViewLineTables::emitDebugInfoForFunction(const Function *GV) {
@@ -138,6 +190,51 @@
     return;
   assert(FI.End && "Don't know where the function ends?");
 
+  StringRef FuncName = getDISubprogram(GV).getDisplayName(),
+            GVName = GV->getName();
+  // FIXME Clang currently sets DisplayName to "bar" for a C++
+  // "namespace_foo::bar" function, see PR21528.  Luckily, dbghelp.dll is trying
+  // to demangle display names anyways, so let's just put a mangled name into
+  // the symbols subsection until Clang gives us what we need.
+  if (GVName.startswith("\01?"))
+    FuncName = GVName.substr(1);
+  // Emit a symbol subsection, required by VS2012+ to find function boundaries.
+  MCSymbol *SymbolsBegin = Asm->MMI->getContext().CreateTempSymbol(),
+           *SymbolsEnd = Asm->MMI->getContext().CreateTempSymbol();
+  Asm->OutStreamer.AddComment("Symbol subsection for " + Twine(FuncName));
+  Asm->EmitInt32(COFF::DEBUG_SYMBOL_SUBSECTION);
+  EmitLabelDiff(Asm->OutStreamer, SymbolsBegin, SymbolsEnd);
+  Asm->OutStreamer.EmitLabel(SymbolsBegin);
+  {
+    MCSymbol *ProcSegmentBegin = Asm->MMI->getContext().CreateTempSymbol(),
+             *ProcSegmentEnd = Asm->MMI->getContext().CreateTempSymbol();
+    EmitLabelDiff(Asm->OutStreamer, ProcSegmentBegin, ProcSegmentEnd, 2);
+    Asm->OutStreamer.EmitLabel(ProcSegmentBegin);
+
+    Asm->EmitInt16(COFF::DEBUG_SYMBOL_TYPE_PROC_START);
+    // Some bytes of this segment don't seem to be required for basic debugging,
+    // so just fill them with zeroes.
+    Asm->OutStreamer.EmitFill(12, 0);
+    // This is the important bit that tells the debugger where the function
+    // code is located and what's its size:
+    EmitLabelDiff(Asm->OutStreamer, Fn, FI.End);
+    Asm->OutStreamer.EmitFill(12, 0);
+    Asm->OutStreamer.EmitCOFFSecRel32(Fn);
+    Asm->OutStreamer.EmitCOFFSectionIndex(Fn);
+    Asm->EmitInt8(0);
+    // Emit the function display name as a null-terminated string.
+    Asm->OutStreamer.EmitBytes(FuncName);
+    Asm->EmitInt8(0);
+    Asm->OutStreamer.EmitLabel(ProcSegmentEnd);
+
+    // We're done with this function.
+    Asm->EmitInt16(0x0002);
+    Asm->EmitInt16(COFF::DEBUG_SYMBOL_TYPE_PROC_END);
+  }
+  Asm->OutStreamer.EmitLabel(SymbolsEnd);
+  // Every subsection must be aligned to a 4-byte boundary.
+  Asm->OutStreamer.EmitFill((-FuncName.size()) % 4, 0);
+
   // PCs/Instructions are grouped into segments sharing the same filename.
   // Pre-calculate the lengths (in instructions) of these segments and store
   // them in a map for convenience.  Each index in the map is the sequential
@@ -154,18 +251,19 @@
   }
   FilenameSegmentLengths[LastSegmentEnd] = FI.Instrs.size() - LastSegmentEnd;
 
-  // Emit the control code of the subsection followed by the payload size.
-  Asm->OutStreamer.AddComment(
-      "Linetable subsection for " + Twine(Fn->getName()));
+  // Emit a line table subsection, requred to do PC-to-file:line lookup.
+  Asm->OutStreamer.AddComment("Line table subsection for " + Twine(FuncName));
   Asm->EmitInt32(COFF::DEBUG_LINE_TABLE_SUBSECTION);
-  MCSymbol *SubsectionBegin = Asm->MMI->getContext().CreateTempSymbol(),
-           *SubsectionEnd = Asm->MMI->getContext().CreateTempSymbol();
-  EmitLabelDiff(Asm->OutStreamer, SubsectionBegin, SubsectionEnd);
-  Asm->OutStreamer.EmitLabel(SubsectionBegin);
+  MCSymbol *LineTableBegin = Asm->MMI->getContext().CreateTempSymbol(),
+           *LineTableEnd = Asm->MMI->getContext().CreateTempSymbol();
+  EmitLabelDiff(Asm->OutStreamer, LineTableBegin, LineTableEnd);
+  Asm->OutStreamer.EmitLabel(LineTableBegin);
 
   // Identify the function this subsection is for.
   Asm->OutStreamer.EmitCOFFSecRel32(Fn);
   Asm->OutStreamer.EmitCOFFSectionIndex(Fn);
+  // Insert padding after a 16-bit section index.
+  Asm->EmitInt16(0);
 
   // Length of the function's code, in bytes.
   EmitLabelDiff(Asm->OutStreamer, Fn, FI.End);
@@ -209,56 +307,7 @@
 
   if (FileSegmentEnd)
     Asm->OutStreamer.EmitLabel(FileSegmentEnd);
-  Asm->OutStreamer.EmitLabel(SubsectionEnd);
-}
-
-void WinCodeViewLineTables::endModule() {
-  if (FnDebugInfo.empty())
-    return;
-
-  assert(Asm != nullptr);
-  Asm->OutStreamer.SwitchSection(
-      Asm->getObjFileLowering().getCOFFDebugSymbolsSection());
-  Asm->EmitInt32(COFF::DEBUG_SECTION_MAGIC);
-
-  // The COFF .debug$S section consists of several subsections, each starting
-  // with a 4-byte control code (e.g. 0xF1, 0xF2, etc) and then a 4-byte length
-  // of the payload followed by the payload itself.  The subsections are 4-byte
-  // aligned.
-
-  for (size_t I = 0, E = VisitedFunctions.size(); I != E; ++I)
-    emitDebugInfoForFunction(VisitedFunctions[I]);
-
-  // This subsection holds a file index to offset in string table table.
-  Asm->OutStreamer.AddComment("File index to string table offset subsection");
-  Asm->EmitInt32(COFF::DEBUG_INDEX_SUBSECTION);
-  size_t NumFilenames = FileNameRegistry.Infos.size();
-  Asm->EmitInt32(8 * NumFilenames);
-  for (size_t I = 0, E = FileNameRegistry.Filenames.size(); I != E; ++I) {
-    StringRef Filename = FileNameRegistry.Filenames[I];
-    // For each unique filename, just write it's offset in the string table.
-    Asm->EmitInt32(FileNameRegistry.Infos[Filename].StartOffset);
-    // The function name offset is not followed by any additional data.
-    Asm->EmitInt32(0);
-  }
-
-  // This subsection holds the string table.
-  Asm->OutStreamer.AddComment("String table");
-  Asm->EmitInt32(COFF::DEBUG_STRING_TABLE_SUBSECTION);
-  Asm->EmitInt32(FileNameRegistry.LastOffset);
-  // The payload starts with a null character.
-  Asm->EmitInt8(0);
-
-  for (size_t I = 0, E = FileNameRegistry.Filenames.size(); I != E; ++I) {
-    // Just emit unique filenames one by one, separated by a null character.
-    Asm->OutStreamer.EmitBytes(FileNameRegistry.Filenames[I]);
-    Asm->EmitInt8(0);
-  }
-
-  // No more subsections. Fill with zeros to align the end of the section by 4.
-  Asm->OutStreamer.EmitFill((-FileNameRegistry.LastOffset) % 4, 0);
-
-  clear();
+  Asm->OutStreamer.EmitLabel(LineTableEnd);
 }
 
 void WinCodeViewLineTables::beginFunction(const MachineFunction *MF) {
diff --git a/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h b/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h
index 0734d97..8492eac 100644
--- a/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h
+++ b/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.h
@@ -11,8 +11,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef CODEGEN_ASMPRINTER_WINCODEVIEWLINETABLES_H__
-#define CODEGEN_ASMPRINTER_WINCODEVIEWLINETABLES_H__
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_WINCODEVIEWLINETABLES_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_WINCODEVIEWLINETABLES_H
 
 #include "AsmPrinterHandler.h"
 #include "llvm/ADT/DenseMap.h"