Merge commit '7dfcb84fc16b3bf6b2379713b53090757f0a45f9'

Conflicts:
	docs/LangRef.rst
	include/llvm/CodeGen/CallingConvLower.h
	include/llvm/IRReader/IRReader.h
	include/llvm/Target/TargetMachine.h
	lib/CodeGen/CallingConvLower.cpp
	lib/IRReader/IRReader.cpp
	lib/IRReader/LLVMBuild.txt
	lib/IRReader/Makefile
	lib/LLVMBuild.txt
	lib/Makefile
	lib/Support/MemoryBuffer.cpp
	lib/Support/Unix/PathV2.inc
	lib/Target/ARM/ARMBaseInstrInfo.cpp
	lib/Target/ARM/ARMISelLowering.cpp
	lib/Target/ARM/ARMInstrInfo.td
	lib/Target/ARM/ARMSubtarget.cpp
	lib/Target/ARM/ARMTargetMachine.cpp
	lib/Target/Mips/CMakeLists.txt
	lib/Target/Mips/MipsDelaySlotFiller.cpp
	lib/Target/Mips/MipsISelLowering.cpp
	lib/Target/Mips/MipsInstrInfo.td
	lib/Target/Mips/MipsSubtarget.cpp
	lib/Target/Mips/MipsSubtarget.h
	lib/Target/X86/X86FastISel.cpp
	lib/Target/X86/X86ISelDAGToDAG.cpp
	lib/Target/X86/X86ISelLowering.cpp
	lib/Target/X86/X86InstrControl.td
	lib/Target/X86/X86InstrFormats.td
	lib/Transforms/IPO/ExtractGV.cpp
	lib/Transforms/InstCombine/InstCombineCompares.cpp
	lib/Transforms/Utils/SimplifyLibCalls.cpp
	test/CodeGen/X86/fast-isel-divrem.ll
	test/MC/ARM/data-in-code.ll
	tools/Makefile
	tools/llvm-extract/llvm-extract.cpp
	tools/llvm-link/CMakeLists.txt
	tools/opt/CMakeLists.txt
	tools/opt/LLVMBuild.txt
	tools/opt/Makefile
	tools/opt/opt.cpp

10 files changed, 423 insertions, 236 deletions

diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 0f381c6d0c..c73071e12b 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -133,9 +133,13 @@ const DataLayout &AsmPrinter::getDataLayout() const {
   return *TM.getDataLayout();
 }
 
+StringRef AsmPrinter::getTargetTriple() const {
+  return TM.getTargetTriple();
+}
+
 /// getCurrentSection() - Return the current section we are emitting to.
 const MCSection *AsmPrinter::getCurrentSection() const {
-  return OutStreamer.getCurrentSection();
+  return OutStreamer.getCurrentSection().first;
 }
 
 
@@ -834,7 +838,7 @@ void AsmPrinter::EmitDwarfRegOp(const MachineLocation &MLoc) const {
   // caller might be in the middle of an dwarf expression. We should
   // probably assert that Reg >= 0 once debug info generation is more mature.
 
-  if (int Offset =  MLoc.getOffset()) {
+  if (MLoc.isIndirect()) {
     if (Reg < 32) {
       OutStreamer.AddComment(
         dwarf::OperationEncodingString(dwarf::DW_OP_breg0 + Reg));
@@ -845,7 +849,7 @@ void AsmPrinter::EmitDwarfRegOp(const MachineLocation &MLoc) const {
       OutStreamer.AddComment(Twine(Reg));
       EmitULEB128(Reg);
     }
-    EmitSLEB128(Offset);
+    EmitSLEB128(MLoc.getOffset());
   } else {
     if (Reg < 32) {
       OutStreamer.AddComment(
@@ -1256,7 +1260,7 @@ void AsmPrinter::EmitJumpTableEntry(const MachineJumpTableInfo *MJTI,
 bool AsmPrinter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
   if (GV->getName() == "llvm.used") {
     if (MAI->hasNoDeadStrip())    // No need to emit this at all.
-      EmitLLVMUsedList(GV->getInitializer());
+      EmitLLVMUsedList(cast<ConstantArray>(GV->getInitializer()));
     return true;
   }
 
@@ -1299,11 +1303,8 @@ bool AsmPrinter::EmitSpecialLLVMGlobal(const GlobalVariable *GV) {
 /// EmitLLVMUsedList - For targets that define a MAI::UsedDirective, mark each
 /// global in the specified llvm.used list for which emitUsedDirectiveFor
 /// is true, as being used with this directive.
-void AsmPrinter::EmitLLVMUsedList(const Constant *List) {
+void AsmPrinter::EmitLLVMUsedList(const ConstantArray *InitList) {
   // Should be an array of 'i8*'.
-  const ConstantArray *InitList = dyn_cast<ConstantArray>(List);
-  if (InitList == 0) return;
-
   for (unsigned i = 0, e = InitList->getNumOperands(); i != e; ++i) {
     const GlobalValue *GV =
       dyn_cast<GlobalValue>(InitList->getOperand(i)->stripPointerCasts());
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp b/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
index 156acace55..31e42d47cf 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp
@@ -141,7 +141,7 @@ void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
 void AsmPrinter::EmitSectionOffset(const MCSymbol *Label,
                                    const MCSymbol *SectionLabel) const {
   // On COFF targets, we have to emit the special .secrel32 directive.
-  if (MAI->getDwarfSectionOffsetDirective()) {
+  if (MAI->needsDwarfSectionOffsetDirective()) {
     OutStreamer.EmitCOFFSecRel32(Label);
     return;
   }
diff --git a/lib/CodeGen/AsmPrinter/CMakeLists.txt b/lib/CodeGen/AsmPrinter/CMakeLists.txt
index 58fe2ed9d3..8d15c069c6 100644
--- a/lib/CodeGen/AsmPrinter/CMakeLists.txt
+++ b/lib/CodeGen/AsmPrinter/CMakeLists.txt
@@ -9,6 +9,7 @@ add_llvm_library(LLVMAsmPrinter
   DwarfCompileUnit.cpp
   DwarfDebug.cpp
   DwarfException.cpp
+  ErlangGCPrinter.cpp
   OcamlGCPrinter.cpp
   Win64Exception.cpp
   )
diff --git a/lib/CodeGen/AsmPrinter/DIE.cpp b/lib/CodeGen/AsmPrinter/DIE.cpp
index 4ded2818ed..673867ada1 100644
--- a/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -112,9 +112,20 @@ DIE::~DIE() {
     delete Children[i];
 }
 
+/// Climb up the parent chain to get the compile unit DIE to which this DIE
+/// belongs.
+DIE *DIE::getCompileUnit() const {
+  DIE *p = getParent();
+  while (p) {
+    if (p->getTag() == dwarf::DW_TAG_compile_unit)
+      return p;
+    p = p->getParent();
+  }
+  llvm_unreachable("We should not have orphaned DIEs.");
+}
+
 #ifndef NDEBUG
-void DIE::print(raw_ostream &O, unsigned IncIndent) {
-  IndentCount += IncIndent;
+void DIE::print(raw_ostream &O, unsigned IndentCount) const {
   const std::string Indent(IndentCount, ' ');
   bool isBlock = Abbrev.getTag() == 0;
 
@@ -133,7 +144,7 @@ void DIE::print(raw_ostream &O, unsigned IncIndent) {
     O << "Size: " << Size << "\n";
   }
 
-  const SmallVector<DIEAbbrevData, 8> &Data = Abbrev.getData();
+  const SmallVectorImpl<DIEAbbrevData> &Data = Abbrev.getData();
 
   IndentCount += 2;
   for (unsigned i = 0, N = Data.size(); i < N; ++i) {
@@ -153,11 +164,10 @@ void DIE::print(raw_ostream &O, unsigned IncIndent) {
   IndentCount -= 2;
 
   for (unsigned j = 0, M = Children.size(); j < M; ++j) {
-    Children[j]->print(O, 4);
+    Children[j]->print(O, IndentCount+4);
   }
 
   if (!isBlock) O << "\n";
-  IndentCount -= IncIndent;
 }
 
 void DIE::dump() {
@@ -313,7 +323,7 @@ void DIEEntry::print(raw_ostream &O) {
 ///
 unsigned DIEBlock::ComputeSize(AsmPrinter *AP) {
   if (!Size) {
-    const SmallVector<DIEAbbrevData, 8> &AbbrevData = Abbrev.getData();
+    const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
     for (unsigned i = 0, N = Values.size(); i < N; ++i)
       Size += Values[i]->SizeOf(AP, AbbrevData[i].getForm());
   }
@@ -332,7 +342,7 @@ void DIEBlock::EmitValue(AsmPrinter *Asm, unsigned Form) const {
   case dwarf::DW_FORM_block:  Asm->EmitULEB128(Size); break;
   }
 
-  const SmallVector<DIEAbbrevData, 8> &AbbrevData = Abbrev.getData();
+  const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
   for (unsigned i = 0, N = Values.size(); i < N; ++i)
     Values[i]->EmitValue(Asm, AbbrevData[i].getForm());
 }
diff --git a/lib/CodeGen/AsmPrinter/DIE.h b/lib/CodeGen/AsmPrinter/DIE.h
index 35d7959ac1..3c06001686 100644
--- a/lib/CodeGen/AsmPrinter/DIE.h
+++ b/lib/CodeGen/AsmPrinter/DIE.h
@@ -66,7 +66,7 @@ namespace llvm {
 
     /// Data - Raw data bytes for abbreviation.
     ///
-    SmallVector<DIEAbbrevData, 8> Data;
+    SmallVector<DIEAbbrevData, 12> Data;
 
   public:
     DIEAbbrev(uint16_t T, uint16_t C) : Tag(T), ChildrenFlag(C), Data() {}
@@ -75,7 +75,7 @@ namespace llvm {
     uint16_t getTag() const { return Tag; }
     unsigned getNumber() const { return Number; }
     uint16_t getChildrenFlag() const { return ChildrenFlag; }
-    const SmallVector<DIEAbbrevData, 8> &getData() const { return Data; }
+    const SmallVectorImpl<DIEAbbrevData> &getData() const { return Data; }
     void setTag(uint16_t T) { Tag = T; }
     void setChildrenFlag(uint16_t CF) { ChildrenFlag = CF; }
     void setNumber(unsigned N) { Number = N; }
@@ -108,7 +108,7 @@ namespace llvm {
 
   //===--------------------------------------------------------------------===//
   /// DIE - A structured debug information entry.  Has an abbreviation which
-  /// describes it's organization.
+  /// describes its organization.
   class DIEValue;
 
   class DIE {
@@ -133,14 +133,13 @@ namespace llvm {
 
     /// Attribute values.
     ///
-    SmallVector<DIEValue*, 32> Values;
+    SmallVector<DIEValue*, 12> Values;
 
     // Private data for print()
     mutable unsigned IndentCount;
   public:
     explicit DIE(unsigned Tag)
-      : Offset(0), Size(0), Abbrev(Tag, dwarf::DW_CHILDREN_no), Parent(0),
-        IndentCount(0) {}
+      : Offset(0), Size(0), Abbrev(Tag, dwarf::DW_CHILDREN_no), Parent(0) {}
     virtual ~DIE();
 
     // Accessors.
@@ -150,8 +149,11 @@ namespace llvm {
     unsigned getOffset() const { return Offset; }
     unsigned getSize() const { return Size; }
     const std::vector<DIE *> &getChildren() const { return Children; }
-    const SmallVector<DIEValue*, 32> &getValues() const { return Values; }
+    const SmallVectorImpl<DIEValue*> &getValues() const { return Values; }
     DIE *getParent() const { return Parent; }
+    /// Climb up the parent chain to get the compile unit DIE this DIE belongs
+    /// to.
+    DIE *getCompileUnit() const;
     void setTag(unsigned Tag) { Abbrev.setTag(Tag); }
     void setOffset(unsigned O) { Offset = O; }
     void setSize(unsigned S) { Size = S; }
@@ -176,7 +178,7 @@ namespace llvm {
     }
 
 #ifndef NDEBUG
-    void print(raw_ostream &O, unsigned IncIndent = 0);
+    void print(raw_ostream &O, unsigned IndentCount = 0) const;
     void dump();
 #endif
   };
@@ -232,9 +234,10 @@ namespace llvm {
     ///
     static unsigned BestForm(bool IsSigned, uint64_t Int) {
       if (IsSigned) {
-        if ((char)Int == (signed)Int)   return dwarf::DW_FORM_data1;
-        if ((short)Int == (signed)Int)  return dwarf::DW_FORM_data2;
-        if ((int)Int == (signed)Int)    return dwarf::DW_FORM_data4;
+        const int64_t SignedInt = Int;
+        if ((char)Int == SignedInt)     return dwarf::DW_FORM_data1;
+        if ((short)Int == SignedInt)    return dwarf::DW_FORM_data2;
+        if ((int)Int == SignedInt)      return dwarf::DW_FORM_data4;
       } else {
         if ((unsigned char)Int == Int)  return dwarf::DW_FORM_data1;
         if ((unsigned short)Int == Int) return dwarf::DW_FORM_data2;
diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index d9f6b5eb0a..89abcffd93 100644
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -35,7 +35,7 @@ using namespace llvm;
 CompileUnit::CompileUnit(unsigned UID, unsigned L, DIE *D, AsmPrinter *A,
                          DwarfDebug *DW, DwarfUnits *DWU)
   : UniqueID(UID), Language(L), CUDie(D), Asm(A), DD(DW), DU(DWU),
-    IndexTyDie(0) {
+    IndexTyDie(0), DebugInfoOffset(0) {
   DIEIntegerOne = new (DIEValueAllocator) DIEInteger(1);
 }
 
@@ -241,7 +241,8 @@ void CompileUnit::addSourceLine(DIE *Die, DIVariable V) {
   if (Line == 0)
     return;
   unsigned FileID = DD->getOrCreateSourceID(V.getContext().getFilename(),
-                                            V.getContext().getDirectory());
+                                            V.getContext().getDirectory(),
+                                            getUniqueID());
   assert(FileID && "Invalid file id");
   addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
   addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
@@ -257,7 +258,8 @@ void CompileUnit::addSourceLine(DIE *Die, DIGlobalVariable G) {
   unsigned Line = G.getLineNumber();
   if (Line == 0)
     return;
-  unsigned FileID = DD->getOrCreateSourceID(G.getFilename(), G.getDirectory());
+  unsigned FileID = DD->getOrCreateSourceID(G.getFilename(), G.getDirectory(),
+                                            getUniqueID());
   assert(FileID && "Invalid file id");
   addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
   addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
@@ -276,7 +278,7 @@ void CompileUnit::addSourceLine(DIE *Die, DISubprogram SP) {
     return;
 
   unsigned FileID = DD->getOrCreateSourceID(SP.getFilename(),
-                                            SP.getDirectory());
+                                            SP.getDirectory(), getUniqueID());
   assert(FileID && "Invalid file id");
   addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
   addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
@@ -293,7 +295,7 @@ void CompileUnit::addSourceLine(DIE *Die, DIType Ty) {
   if (Line == 0)
     return;
   unsigned FileID = DD->getOrCreateSourceID(Ty.getFilename(),
-                                            Ty.getDirectory());
+                                            Ty.getDirectory(), getUniqueID());
   assert(FileID && "Invalid file id");
   addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
   addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
@@ -311,7 +313,7 @@ void CompileUnit::addSourceLine(DIE *Die, DIObjCProperty Ty) {
     return;
   DIFile File = Ty.getFile();
   unsigned FileID = DD->getOrCreateSourceID(File.getFilename(),
-                                            File.getDirectory());
+                                            File.getDirectory(), getUniqueID());
   assert(FileID && "Invalid file id");
   addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
   addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
@@ -329,7 +331,8 @@ void CompileUnit::addSourceLine(DIE *Die, DINameSpace NS) {
     return;
   StringRef FN = NS.getFilename();
 
-  unsigned FileID = DD->getOrCreateSourceID(FN, NS.getDirectory());
+  unsigned FileID = DD->getOrCreateSourceID(FN, NS.getDirectory(),
+                                            getUniqueID());
   assert(FileID && "Invalid file id");
   addUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
   addUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
@@ -682,7 +685,7 @@ bool CompileUnit::addConstantValue(DIE *Die, const APInt &Val,
   return true;
 }
 
-/// addTemplateParams - Add template parameters in buffer.
+/// addTemplateParams - Add template parameters into buffer.
 void CompileUnit::addTemplateParams(DIE &Buffer, DIArray TParams) {
   // Add template parameters.
   for (unsigned i = 0, e = TParams.getNumElements(); i != e; ++i) {
@@ -704,7 +707,7 @@ DIE *CompileUnit::getOrCreateContextDIE(DIDescriptor Context) {
     return getOrCreateNameSpace(DINameSpace(Context));
   else if (Context.isSubprogram())
     return getOrCreateSubprogramDIE(DISubprogram(Context));
-  else 
+  else
     return getDIE(Context);
 }
 
@@ -1363,7 +1366,7 @@ void CompileUnit::createGlobalVariableDIE(const MDNode *N) {
     }
   } else if (const ConstantInt *CI =
              dyn_cast_or_null<ConstantInt>(GV.getConstant())) {
-    // AT_const_value was added when the static memeber was created. To avoid
+    // 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)
@@ -1669,33 +1672,6 @@ DIE *CompileUnit::createMemberDIE(DIDerivedType DT) {
   if (DT.isArtificial())
     addFlag(MemberDie, dwarf::DW_AT_artificial);
 
-  // This is only for backward compatibility.
-  StringRef PropertyName = DT.getObjCPropertyName();
-  if (!PropertyName.empty()) {
-    addString(MemberDie, dwarf::DW_AT_APPLE_property_name, PropertyName);
-    StringRef GetterName = DT.getObjCPropertyGetterName();
-    if (!GetterName.empty())
-      addString(MemberDie, dwarf::DW_AT_APPLE_property_getter, GetterName);
-    StringRef SetterName = DT.getObjCPropertySetterName();
-    if (!SetterName.empty())
-      addString(MemberDie, dwarf::DW_AT_APPLE_property_setter, SetterName);
-    unsigned PropertyAttributes = 0;
-    if (DT.isReadOnlyObjCProperty())
-      PropertyAttributes |= dwarf::DW_APPLE_PROPERTY_readonly;
-    if (DT.isReadWriteObjCProperty())
-      PropertyAttributes |= dwarf::DW_APPLE_PROPERTY_readwrite;
-    if (DT.isAssignObjCProperty())
-      PropertyAttributes |= dwarf::DW_APPLE_PROPERTY_assign;
-    if (DT.isRetainObjCProperty())
-      PropertyAttributes |= dwarf::DW_APPLE_PROPERTY_retain;
-    if (DT.isCopyObjCProperty())
-      PropertyAttributes |= dwarf::DW_APPLE_PROPERTY_copy;
-    if (DT.isNonAtomicObjCProperty())
-      PropertyAttributes |= dwarf::DW_APPLE_PROPERTY_nonatomic;
-    if (PropertyAttributes)
-      addUInt(MemberDie, dwarf::DW_AT_APPLE_property_attribute, 0,
-              PropertyAttributes);
-  }
   return MemberDie;
 }
 
diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
index 77bf6a9e50..8f08c63e64 100644
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -87,13 +87,13 @@ class CompileUnit {
   /// corresponds to the MDNode mapped with the subprogram DIE.
   DenseMap<DIE *, const MDNode *> ContainingTypeMap;
 
+  /// Offset of the CUDie from beginning of debug info section.
+  unsigned DebugInfoOffset;
+
   /// getLowerBoundDefault - Return the default lower bound for an array. If the
   /// DWARF version doesn't handle the language, return -1.
   int64_t getDefaultLowerBound() const;
 
-  /// getOrCreateContextDIE - Get context owner's DIE.
-  DIE *getOrCreateContextDIE(DIDescriptor Context);
-
 public:
   CompileUnit(unsigned UID, unsigned L, DIE *D, AsmPrinter *A, DwarfDebug *DW,
               DwarfUnits *);
@@ -103,6 +103,7 @@ public:
   unsigned getUniqueID()            const { return UniqueID; }
   unsigned getLanguage()            const { return Language; }
   DIE* getCUDie()                   const { return CUDie.get(); }
+  unsigned getDebugInfoOffset()     const { return DebugInfoOffset; }
   const StringMap<DIE*> &getGlobalNames() const { return GlobalNames; }
   const StringMap<DIE*> &getGlobalTypes() const { return GlobalTypes; }
 
@@ -120,6 +121,7 @@ public:
     return AccelTypes;
   }
 
+  void setDebugInfoOffset(unsigned DbgInfoOff) { DebugInfoOffset = DbgInfoOff; }
   /// hasContent - Return true if this compile unit has something to write out.
   ///
   bool hasContent() const { return !CUDie->getChildren().empty(); }
@@ -367,6 +369,9 @@ public:
   /// createStaticMemberDIE - Create new static data member DIE.
   DIE *createStaticMemberDIE(DIDerivedType DT);
 
+  /// getOrCreateContextDIE - Get context owner's DIE.
+  DIE *getOrCreateContextDIE(DIDescriptor Context);
+
 private:
 
   // DIEValueAllocator - All DIEValues are allocated through this allocator.
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 87659ef667..73bba6989f 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -55,7 +55,7 @@ static cl::opt<bool> UnknownLocations("use-unknown-locations", cl::Hidden,
      cl::init(false));
 
 static cl::opt<bool> GenerateDwarfPubNamesSection("generate-dwarf-pubnames",
-     cl::Hidden, cl::ZeroOrMore, cl::init(false),
+     cl::Hidden, cl::init(false),
      cl::desc("Generate DWARF pubnames section"));
 
 namespace {
@@ -94,6 +94,12 @@ static cl::opt<DefaultOnOff> SplitDwarf("split-dwarf", cl::Hidden,
 namespace {
   const char *DWARFGroupName = "DWARF Emission";
   const char *DbgTimerName = "DWARF Debug Writer";
+
+  struct CompareFirst {
+    template <typename T> bool operator()(const T &lhs, const T &rhs) const {
+      return lhs.first < rhs.first;
+    }
+  };
 } // end anonymous namespace
 
 //===----------------------------------------------------------------------===//
@@ -170,12 +176,13 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   DwarfInfoSectionSym = DwarfAbbrevSectionSym = 0;
   DwarfStrSectionSym = TextSectionSym = 0;
   DwarfDebugRangeSectionSym = DwarfDebugLocSectionSym = DwarfLineSectionSym = 0;
+  DwarfAddrSectionSym = 0;
   DwarfAbbrevDWOSectionSym = DwarfStrDWOSectionSym = 0;
   FunctionBeginSym = FunctionEndSym = 0;
 
   // Turn on accelerator tables and older gdb compatibility
   // for Darwin.
-  bool IsDarwin = Triple(M->getTargetTriple()).isOSDarwin();
+  bool IsDarwin = Triple(A->getTargetTriple()).isOSDarwin();
   if (DarwinGDBCompat == Default) {
     if (IsDarwin)
       IsDarwinGDBCompat = true;
@@ -352,11 +359,16 @@ DIE *DwarfDebug::updateSubprogramScopeDIE(CompileUnit *SPCU,
   // If we're updating an abstract DIE, then we will be adding the children and
   // object pointer later on. But what we don't want to do is process the
   // concrete DIE twice.
-  if (DIE *AbsSPDIE = AbstractSPDies.lookup(SPNode)) {
+  DIE *AbsSPDIE = AbstractSPDies.lookup(SPNode);
+  if (AbsSPDIE) {
+    bool InSameCU = (AbsSPDIE->getCompileUnit() == SPCU->getCUDie());
     // Pick up abstract subprogram DIE.
     SPDie = new DIE(dwarf::DW_TAG_subprogram);
+    // If AbsSPDIE belongs to a different CU, use DW_FORM_ref_addr instead of
+    // DW_FORM_ref4.
     SPCU->addDIEEntry(SPDie, dwarf::DW_AT_abstract_origin,
-                      dwarf::DW_FORM_ref4, AbsSPDIE);
+                      InSameCU ? dwarf::DW_FORM_ref4 : dwarf::DW_FORM_ref_addr,
+                      AbsSPDIE);
     SPCU->addDie(SPDie);
   } else {
     DISubprogram SPDecl = SP.getFunctionDeclaration();
@@ -528,7 +540,8 @@ DIE *DwarfDebug::constructInlinedScopeDIE(CompileUnit *TheCU,
 
   DILocation DL(Scope->getInlinedAt());
   TheCU->addUInt(ScopeDIE, dwarf::DW_AT_call_file, 0,
-                 getOrCreateSourceID(DL.getFilename(), DL.getDirectory()));
+                 getOrCreateSourceID(DL.getFilename(), DL.getDirectory(),
+                                     TheCU->getUniqueID()));
   TheCU->addUInt(ScopeDIE, dwarf::DW_AT_call_line, 0, DL.getLineNumber());
 
   // Add name to the name table, we do this here because we're guaranteed
@@ -590,9 +603,16 @@ DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
   }
   else {
     // There is no need to emit empty lexical block DIE.
-    if (Children.empty())
+    std::pair<ImportedEntityMap::const_iterator,
+              ImportedEntityMap::const_iterator> Range = std::equal_range(
+        ScopesWithImportedEntities.begin(), ScopesWithImportedEntities.end(),
+        std::pair<const MDNode *, const MDNode *>(DS, (const MDNode*)0),
+        CompareFirst());
+    if (Children.empty() && Range.first == Range.second)
       return NULL;
     ScopeDIE = constructLexicalScopeDIE(TheCU, Scope);
+    for (ImportedEntityMap::const_iterator i = Range.first; i != Range.second; ++i)
+      constructImportedModuleDIE(TheCU, i->second, ScopeDIE);
   }
 
   if (!ScopeDIE) return NULL;
@@ -617,19 +637,28 @@ DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
 // SourceIds map. This can update DirectoryNames and SourceFileNames maps
 // as well.
 unsigned DwarfDebug::getOrCreateSourceID(StringRef FileName,
-                                         StringRef DirName) {
+                                         StringRef DirName, unsigned CUID) {
+  // If we use .loc in assembly, we can't separate .file entries according to
+  // compile units. Thus all files will belong to the default compile unit.
+  if (Asm->TM.hasMCUseLoc() &&
+      Asm->OutStreamer.getKind() == MCStreamer::SK_AsmStreamer)
+    CUID = 0;
+
   // If FE did not provide a file name, then assume stdin.
   if (FileName.empty())
-    return getOrCreateSourceID("<stdin>", StringRef());
+    return getOrCreateSourceID("<stdin>", StringRef(), CUID);
 
   // TODO: this might not belong here. See if we can factor this better.
   if (DirName == CompilationDir)
     DirName = "";
 
-  unsigned SrcId = SourceIdMap.size()+1;
+  // FileIDCUMap stores the current ID for the given compile unit.
+  unsigned SrcId = FileIDCUMap[CUID] + 1;
 
-  // We look up the file/dir pair by concatenating them with a zero byte.
+  // We look up the CUID/file/dir by concatenating them with a zero byte.
   SmallString<128> NamePair;
+  NamePair += utostr(CUID);
+  NamePair += '\0';
   NamePair += DirName;
   NamePair += '\0'; // Zero bytes are not allowed in paths.
   NamePair += FileName;
@@ -638,8 +667,9 @@ unsigned DwarfDebug::getOrCreateSourceID(StringRef FileName,
   if (Ent.getValue() != SrcId)
     return Ent.getValue();
 
+  FileIDCUMap[CUID] = SrcId;
   // Print out a .file directive to specify files for .loc directives.
-  Asm->OutStreamer.EmitDwarfFileDirective(SrcId, DirName, FileName);
+  Asm->OutStreamer.EmitDwarfFileDirective(SrcId, DirName, FileName, CUID);
 
   return SrcId;
 }
@@ -650,21 +680,27 @@ CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
   DICompileUnit DIUnit(N);
   StringRef FN = DIUnit.getFilename();
   CompilationDir = DIUnit.getDirectory();
-  // Call this to emit a .file directive if it wasn't emitted for the source
-  // file this CU comes from yet.
-  getOrCreateSourceID(FN, CompilationDir);
 
   DIE *Die = new DIE(dwarf::DW_TAG_compile_unit);
   CompileUnit *NewCU = new CompileUnit(GlobalCUIndexCount++,
                                        DIUnit.getLanguage(), Die, Asm,
                                        this, &InfoHolder);
+
+  FileIDCUMap[NewCU->getUniqueID()] = 0;
+  // Call this to emit a .file directive if it wasn't emitted for the source
+  // file this CU comes from yet.
+  getOrCreateSourceID(FN, CompilationDir, NewCU->getUniqueID());
+
   NewCU->addString(Die, dwarf::DW_AT_producer, DIUnit.getProducer());
   NewCU->addUInt(Die, dwarf::DW_AT_language, dwarf::DW_FORM_data2,
                  DIUnit.getLanguage());
   NewCU->addString(Die, dwarf::DW_AT_name, FN);
+
   // 2.17.1 requires that we use DW_AT_low_pc for a single entry point
-  // into an entity. We're using 0 (or a NULL label) for this.
-  NewCU->addLabelAddress(Die, dwarf::DW_AT_low_pc, NULL);
+  // into an entity. We're using 0 (or a NULL label) for this. For
+  // split dwarf it's in the skeleton CU so omit it here.
+  if (!useSplitDwarf())
+    NewCU->addLabelAddress(Die, dwarf::DW_AT_low_pc, NULL);
 
   // Define start line table label for each Compile Unit.
   MCSymbol *LineTableStartSym = Asm->GetTempSymbol("line_table_start",
@@ -672,21 +708,32 @@ CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
   Asm->OutStreamer.getContext().setMCLineTableSymbol(LineTableStartSym,
                                                      NewCU->getUniqueID());
 
+  // Use a single line table if we are using .loc and generating assembly.
+  bool UseTheFirstCU =
+    (Asm->TM.hasMCUseLoc() &&
+     Asm->OutStreamer.getKind() == MCStreamer::SK_AsmStreamer) ||
+    (NewCU->getUniqueID() == 0);
+
   // DW_AT_stmt_list is a offset of line number information for this
-  // compile unit in debug_line section.
+  // compile unit in debug_line section. For split dwarf this is
+  // left in the skeleton CU and so not included.
   // The line table entries are not always emitted in assembly, so it
   // is not okay to use line_table_start here.
-  if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
-    NewCU->addLabel(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4,
-                    NewCU->getUniqueID() == 0 ?
-                    Asm->GetTempSymbol("section_line") : LineTableStartSym);
-  else if (NewCU->getUniqueID() == 0)
-    NewCU->addUInt(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4, 0);
-  else
-    NewCU->addDelta(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4,
-                    LineTableStartSym, DwarfLineSectionSym);
+  if (!useSplitDwarf()) {
+    if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+      NewCU->addLabel(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4,
+                      UseTheFirstCU ?
+                      Asm->GetTempSymbol("section_line") : LineTableStartSym);
+    else if (UseTheFirstCU)
+      NewCU->addUInt(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4, 0);
+    else
+      NewCU->addDelta(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4,
+                      LineTableStartSym, DwarfLineSectionSym);
+  }
 
-  if (!CompilationDir.empty())
+  // If we're using split dwarf the compilation dir is going to be in the
+  // skeleton CU and so we don't need to duplicate it here.
+  if (!useSplitDwarf() && !CompilationDir.empty())
     NewCU->addString(Die, dwarf::DW_AT_comp_dir, CompilationDir);
   if (DIUnit.isOptimized())
     NewCU->addFlag(Die, dwarf::DW_AT_APPLE_optimized);
@@ -702,13 +749,6 @@ CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
   if (!FirstCU)
     FirstCU = NewCU;
 
-  if (useSplitDwarf()) {
-    // This should be a unique identifier when we want to build .dwp files.
-    NewCU->addUInt(Die, dwarf::DW_AT_GNU_dwo_id, dwarf::DW_FORM_data8, 0);
-    // Now construct the skeleton CU associated.
-    constructSkeletonCU(N);
-  }
-
   InfoHolder.addUnit(NewCU);
 
   CUMap.insert(std::make_pair(N, NewCU));
@@ -742,80 +782,39 @@ void DwarfDebug::constructSubprogramDIE(CompileUnit *TheCU,
     TheCU->addGlobalName(SP.getName(), SubprogramDie);
 }
 
-// Collect debug info from named mdnodes such as llvm.dbg.enum and llvm.dbg.ty.
-void DwarfDebug::collectInfoFromNamedMDNodes(const Module *M) {
-  if (NamedMDNode *NMD = M->getNamedMetadata("llvm.dbg.sp"))
-    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
-      const MDNode *N = NMD->getOperand(i);
-      if (CompileUnit *CU = CUMap.lookup(DISubprogram(N).getCompileUnit()))
-        constructSubprogramDIE(CU, N);
-    }
-
-  if (NamedMDNode *NMD = M->getNamedMetadata("llvm.dbg.gv"))
-    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
-      const MDNode *N = NMD->getOperand(i);
-      if (CompileUnit *CU = CUMap.lookup(DIGlobalVariable(N).getCompileUnit()))
-        CU->createGlobalVariableDIE(N);
-    }
-
-  if (NamedMDNode *NMD = M->getNamedMetadata("llvm.dbg.enum"))
-    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
-      DIType Ty(NMD->getOperand(i));
-      if (CompileUnit *CU = CUMap.lookup(Ty.getCompileUnit()))
-        CU->getOrCreateTypeDIE(Ty);
-    }
-
-  if (NamedMDNode *NMD = M->getNamedMetadata("llvm.dbg.ty"))
-    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
-      DIType Ty(NMD->getOperand(i));
-      if (CompileUnit *CU = CUMap.lookup(Ty.getCompileUnit()))
-        CU->getOrCreateTypeDIE(Ty);
-    }
+void DwarfDebug::constructImportedModuleDIE(CompileUnit *TheCU,
+                                            const MDNode *N) {
+  DIImportedModule Module(N);
+  if (!Module.Verify())
+    return;
+  if (DIE *D = TheCU->getOrCreateContextDIE(Module.getContext()))
+    constructImportedModuleDIE(TheCU, Module, D);
 }
 
-// Collect debug info using DebugInfoFinder.
-// FIXME - Remove this when dragonegg switches to DIBuilder.
-bool DwarfDebug::collectLegacyDebugInfo(const Module *M) {
-  DebugInfoFinder DbgFinder;
-  DbgFinder.processModule(*M);
-
-  bool HasDebugInfo = false;
-  // Scan all the compile-units to see if there are any marked as the main
-  // unit. If not, we do not generate debug info.
-  for (DebugInfoFinder::iterator I = DbgFinder.compile_unit_begin(),
-         E = DbgFinder.compile_unit_end(); I != E; ++I) {
-    if (DICompileUnit(*I).isMain()) {
-      HasDebugInfo = true;
-      break;
-    }
-  }
-  if (!HasDebugInfo) return false;
-
-  // Emit initial sections so we can refer to them later.
-  emitSectionLabels();
-
-  // Create all the compile unit DIEs.
-  for (DebugInfoFinder::iterator I = DbgFinder.compile_unit_begin(),
-         E = DbgFinder.compile_unit_end(); I != E; ++I)
-    constructCompileUnit(*I);
-
-  // Create DIEs for each global variable.
-  for (DebugInfoFinder::iterator I = DbgFinder.global_variable_begin(),
-         E = DbgFinder.global_variable_end(); I != E; ++I) {
-    const MDNode *N = *I;
-    if (CompileUnit *CU = CUMap.lookup(DIGlobalVariable(N).getCompileUnit()))
-      CU->createGlobalVariableDIE(N);
-  }
-
-  // Create DIEs for each subprogram.
-  for (DebugInfoFinder::iterator I = DbgFinder.subprogram_begin(),
-         E = DbgFinder.subprogram_end(); I != E; ++I) {
-    const MDNode *N = *I;
-    if (CompileUnit *CU = CUMap.lookup(DISubprogram(N).getCompileUnit()))
-      constructSubprogramDIE(CU, N);
-  }
-
-  return HasDebugInfo;
+void DwarfDebug::constructImportedModuleDIE(CompileUnit *TheCU, const MDNode *N,
+                                            DIE *Context) {
+  DIImportedModule Module(N);
+  if (!Module.Verify())
+    return;
+  return constructImportedModuleDIE(TheCU, Module, Context);
+}
+
+void DwarfDebug::constructImportedModuleDIE(CompileUnit *TheCU,
+                                            const DIImportedModule &Module,
+                                            DIE *Context) {
+  assert(Module.Verify() &&
+         "Use one of the MDNode * overloads to handle invalid metadata");
+  assert(Context && "Should always have a context for an imported_module");
+  DIE *IMDie = new DIE(dwarf::DW_TAG_imported_module);
+  TheCU->insertDIE(Module, IMDie);
+  DIE *NSDie = TheCU->getOrCreateNameSpace(Module.getNameSpace());
+  unsigned FileID = getOrCreateSourceID(Module.getContext().getFilename(),
+                                        Module.getContext().getDirectory(),
+                                        TheCU->getUniqueID());
+  TheCU->addUInt(IMDie, dwarf::DW_AT_decl_file, 0, FileID);
+  TheCU->addUInt(IMDie, dwarf::DW_AT_decl_line, 0, Module.getLineNumber());
+  TheCU->addDIEEntry(IMDie, dwarf::DW_AT_import, dwarf::DW_FORM_ref4, NSDie);
+  Context->addChild(IMDie);
 }
 
 // Emit all Dwarf sections that should come prior to the content. Create
@@ -830,30 +829,48 @@ void DwarfDebug::beginModule() {
   // 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) {
-    // Emit initial sections so we can reference labels later.
-    emitSectionLabels();
-
-    for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
-      DICompileUnit CUNode(CU_Nodes->getOperand(i));
-      CompileUnit *CU = constructCompileUnit(CUNode);
-      DIArray GVs = CUNode.getGlobalVariables();
-      for (unsigned i = 0, e = GVs.getNumElements(); i != e; ++i)
-        CU->createGlobalVariableDIE(GVs.getElement(i));
-      DIArray SPs = CUNode.getSubprograms();
-      for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i)
-        constructSubprogramDIE(CU, SPs.getElement(i));
-      DIArray EnumTypes = CUNode.getEnumTypes();
-      for (unsigned i = 0, e = EnumTypes.getNumElements(); i != e; ++i)
-        CU->getOrCreateTypeDIE(EnumTypes.getElement(i));
-      DIArray RetainedTypes = CUNode.getRetainedTypes();
-      for (unsigned i = 0, e = RetainedTypes.getNumElements(); i != e; ++i)
-        CU->getOrCreateTypeDIE(RetainedTypes.getElement(i));
-    }
-  } else if (!collectLegacyDebugInfo(M))
+  if (!CU_Nodes)
     return;
 
-  collectInfoFromNamedMDNodes(M);
+  // Emit initial sections so we can reference labels later.
+  emitSectionLabels();
+
+  for (unsigned i = 0, e = CU_Nodes->getNumOperands(); i != e; ++i) {
+    DICompileUnit CUNode(CU_Nodes->getOperand(i));
+    CompileUnit *CU = constructCompileUnit(CUNode);
+    DIArray ImportedModules = CUNode.getImportedModules();
+    for (unsigned i = 0, e = ImportedModules.getNumElements(); i != e; ++i)
+      ScopesWithImportedEntities.push_back(std::make_pair(
+          DIImportedModule(ImportedModules.getElement(i)).getContext(),
+          ImportedModules.getElement(i)));
+    std::sort(ScopesWithImportedEntities.begin(),
+              ScopesWithImportedEntities.end(), CompareFirst());
+    DIArray GVs = CUNode.getGlobalVariables();
+    for (unsigned i = 0, e = GVs.getNumElements(); i != e; ++i)
+      CU->createGlobalVariableDIE(GVs.getElement(i));
+    DIArray SPs = CUNode.getSubprograms();
+    for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i)
+      constructSubprogramDIE(CU, SPs.getElement(i));
+    DIArray EnumTypes = CUNode.getEnumTypes();
+    for (unsigned i = 0, e = EnumTypes.getNumElements(); i != e; ++i)
+      CU->getOrCreateTypeDIE(EnumTypes.getElement(i));
+    DIArray RetainedTypes = CUNode.getRetainedTypes();
+    for (unsigned i = 0, e = RetainedTypes.getNumElements(); i != e; ++i)
+      CU->getOrCreateTypeDIE(RetainedTypes.getElement(i));
+    // Emit imported_modules last so that the relevant context is already
+    // available.
+    for (unsigned i = 0, e = ImportedModules.getNumElements(); i != e; ++i)
+      constructImportedModuleDIE(CU, ImportedModules.getElement(i));
+    // If we're splitting the dwarf out now that we've got the entire
+    // CU then construct a skeleton CU based upon it.
+    if (useSplitDwarf()) {
+      // This should be a unique identifier when we want to build .dwp files.
+      CU->addUInt(CU->getCUDie(), dwarf::DW_AT_GNU_dwo_id,
+                  dwarf::DW_FORM_data8, 0);
+      // Now construct the skeleton CU associated.
+      constructSkeletonCU(CUNode);
+    }
+  }
 
   // Tell MMI that we have debug info.
   MMI->setDebugInfoAvailability(true);
@@ -1157,7 +1174,13 @@ static DotDebugLocEntry getDebugLocEntry(AsmPrinter *Asm,
   }
   if (MI->getOperand(0).isReg() && MI->getOperand(1).isImm()) {
     MachineLocation MLoc;
-    MLoc.set(MI->getOperand(0).getReg(), MI->getOperand(1).getImm());
+    // TODO: Currently an offset of 0 in a DBG_VALUE means
+    // we need to generate a direct register value.
+    // There is no way to specify an indirect value with offset 0.
+    if (MI->getOperand(1).getImm() == 0)
+      MLoc.set(MI->getOperand(0).getReg());
+    else
+      MLoc.set(MI->getOperand(0).getReg(), MI->getOperand(1).getImm());
     return DotDebugLocEntry(FLabel, SLabel, MLoc, Var);
   }
   if (MI->getOperand(0).isImm())
@@ -1197,16 +1220,10 @@ DwarfDebug::collectVariableInfo(const MachineFunction *MF,
     if (DV.getTag() == dwarf::DW_TAG_arg_variable &&
         DISubprogram(DV.getContext()).describes(MF->getFunction()))
       Scope = LScopes.getCurrentFunctionScope();
-    else {
-      if (DV.getVersion() <= LLVMDebugVersion9)
-        Scope = LScopes.findLexicalScope(MInsn->getDebugLoc());
-      else {
-        if (MDNode *IA = DV.getInlinedAt())
-          Scope = LScopes.findInlinedScope(DebugLoc::getFromDILocation(IA));
-        else
-          Scope = LScopes.findLexicalScope(cast<MDNode>(DV->getOperand(1)));
-      }
-    }
+    else if (MDNode *IA = DV.getInlinedAt())
+      Scope = LScopes.findInlinedScope(DebugLoc::getFromDILocation(IA));
+    else
+      Scope = LScopes.findLexicalScope(cast<MDNode>(DV->getOperand(1)));
     // If variable scope is not found then skip this variable.
     if (!Scope)
       continue;
@@ -1430,7 +1447,12 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
   LexicalScope *FnScope = LScopes.getCurrentFunctionScope();
   CompileUnit *TheCU = SPMap.lookup(FnScope->getScopeNode());
   assert(TheCU && "Unable to find compile unit!");
-  Asm->OutStreamer.getContext().setDwarfCompileUnitID(TheCU->getUniqueID());
+  if (Asm->TM.hasMCUseLoc() &&
+      Asm->OutStreamer.getKind() == MCStreamer::SK_AsmStreamer)
+    // Use a single line table if we are using .loc and generating assembly.
+    Asm->OutStreamer.getContext().setDwarfCompileUnitID(0);
+  else
+    Asm->OutStreamer.getContext().setDwarfCompileUnitID(TheCU->getUniqueID());
 
   FunctionBeginSym = Asm->GetTempSymbol("func_begin",
                                         Asm->getFunctionNumber());
@@ -1707,7 +1729,8 @@ void DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, const MDNode *S,
     } else
       llvm_unreachable("Unexpected scope info");
 
-    Src = getOrCreateSourceID(Fn, Dir);
+    Src = getOrCreateSourceID(Fn, Dir,
+            Asm->OutStreamer.getContext().getDwarfCompileUnitID());
   }
   Asm->OutStreamer.EmitDwarfLocDirective(Src, Line, Col, Flags, 0, 0, Fn);
 }
@@ -1735,8 +1758,8 @@ DwarfUnits::computeSizeAndOffset(DIE *Die, unsigned Offset) {
   // Start the size with the size of abbreviation code.
   Offset += MCAsmInfo::getULEB128Size(AbbrevNumber);
 
-  const SmallVector<DIEValue*, 32> &Values = Die->getValues();
-  const SmallVector<DIEAbbrevData, 8> &AbbrevData = Abbrev->getData();
+  const SmallVectorImpl<DIEValue*> &Values = Die->getValues();
+  const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev->getData();
 
   // Size the DIE attribute values.
   for (unsigned i = 0, N = Values.size(); i < N; ++i)
@@ -1761,15 +1784,19 @@ DwarfUnits::computeSizeAndOffset(DIE *Die, unsigned Offset) {
 
 // Compute the size and offset of all the DIEs.
 void DwarfUnits::computeSizeAndOffsets() {
-  for (SmallVector<CompileUnit *, 1>::iterator I = CUs.begin(),
+  // Offset from the beginning of debug info section.
+  unsigned AccuOffset = 0;
+  for (SmallVectorImpl<CompileUnit *>::iterator I = CUs.begin(),
          E = CUs.end(); I != E; ++I) {
+    (*I)->setDebugInfoOffset(AccuOffset);
     unsigned Offset =
       sizeof(int32_t) + // Length of Compilation Unit Info
       sizeof(int16_t) + // DWARF version number
       sizeof(int32_t) + // Offset Into Abbrev. Section
       sizeof(int8_t);   // Pointer Size (in bytes)
 
-    computeSizeAndOffset((*I)->getCUDie(), Offset);
+    unsigned EndOffset = computeSizeAndOffset((*I)->getCUDie(), Offset);
+    AccuOffset += EndOffset;
   }
 }
 
@@ -1799,9 +1826,12 @@ void DwarfDebug::emitSectionLabels() {
   emitSectionSym(Asm, TLOF.getDwarfPubTypesSection());
   DwarfStrSectionSym =
     emitSectionSym(Asm, TLOF.getDwarfStrSection(), "info_string");
-  if (useSplitDwarf())
+  if (useSplitDwarf()) {
     DwarfStrDWOSectionSym =
       emitSectionSym(Asm, TLOF.getDwarfStrDWOSection(), "skel_string");
+    DwarfAddrSectionSym =
+      emitSectionSym(Asm, TLOF.getDwarfAddrSection(), "addr_sec");
+  }
   DwarfDebugRangeSectionSym = emitSectionSym(Asm, TLOF.getDwarfRangesSection(),
                                              "debug_range");
 
@@ -1826,8 +1856,8 @@ void DwarfDebug::emitDIE(DIE *Die, std::vector<DIEAbbrev *> *Abbrevs) {
                                 dwarf::TagString(Abbrev->getTag()));
   Asm->EmitULEB128(AbbrevNumber);
 
-  const SmallVector<DIEValue*, 32> &Values = Die->getValues();
-  const SmallVector<DIEAbbrevData, 8> &AbbrevData = Abbrev->getData();
+  const SmallVectorImpl<DIEValue*> &Values = Die->getValues();
+  const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev->getData();
 
   // Emit the DIE attribute values.
   for (unsigned i = 0, N = Values.size(); i < N; ++i) {
@@ -1843,6 +1873,13 @@ void DwarfDebug::emitDIE(DIE *Die, std::vector<DIEAbbrev *> *Abbrevs) {
       DIEEntry *E = cast<DIEEntry>(Values[i]);
       DIE *Origin = E->getEntry();
       unsigned Addr = Origin->getOffset();
+      if (Form == dwarf::DW_FORM_ref_addr) {
+        // For DW_FORM_ref_addr, output the offset from beginning of debug info
+        // section. Origin->getOffset() returns the offset from start of the
+        // compile unit.
+        DwarfUnits &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
+        Addr += Holder.getCUOffset(Origin->getCompileUnit());
+      }
       Asm->EmitInt32(Addr);
       break;
     }
@@ -1908,7 +1945,7 @@ void DwarfUnits::emitUnits(DwarfDebug *DD,
                            const MCSection *ASection,
                            const MCSymbol *ASectionSym) {
   Asm->OutStreamer.SwitchSection(USection);
-  for (SmallVector<CompileUnit *, 1>::iterator I = CUs.begin(),
+  for (SmallVectorImpl<CompileUnit *>::iterator I = CUs.begin(),
          E = CUs.end(); I != E; ++I) {
     CompileUnit *TheCU = *I;
     DIE *Die = TheCU->getCUDie();
@@ -1940,6 +1977,19 @@ void DwarfUnits::emitUnits(DwarfDebug *DD,
   }
 }
 
+/// For a given compile unit DIE, returns offset from beginning of debug info.
+unsigned DwarfUnits::getCUOffset(DIE *Die) {
+  assert(Die->getTag() == dwarf::DW_TAG_compile_unit  &&
+         "Input DIE should be compile unit in getCUOffset.");
+  for (SmallVectorImpl<CompileUnit *>::iterator I = CUs.begin(),
+       E = CUs.end(); I != E; ++I) {
+    CompileUnit *TheCU = *I;
+    if (TheCU->getCUDie() == Die)
+      return TheCU->getDebugInfoOffset();
+  }
+  llvm_unreachable("The compile unit DIE should belong to CUs in DwarfUnits.");
+}
+
 // Emit the debug info section.
 void DwarfDebug::emitDebugInfo() {
   DwarfUnits &Holder = useSplitDwarf() ? SkeletonHolder : InfoHolder;
@@ -2324,7 +2374,7 @@ void DwarfDebug::emitDebugLoc() {
   if (DotDebugLocEntries.empty())
     return;
 
-  for (SmallVector<DotDebugLocEntry, 4>::iterator
+  for (SmallVectorImpl<DotDebugLocEntry>::iterator
          I = DotDebugLocEntries.begin(), E = DotDebugLocEntries.end();
        I != E; ++I) {
     DotDebugLocEntry &Entry = *I;
@@ -2338,7 +2388,7 @@ void DwarfDebug::emitDebugLoc() {
   unsigned char Size = Asm->getDataLayout().getPointerSize();
   Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("debug_loc", 0));
   unsigned index = 1;
-  for (SmallVector<DotDebugLocEntry, 4>::iterator
+  for (SmallVectorImpl<DotDebugLocEntry>::iterator
          I = DotDebugLocEntries.begin(), E = DotDebugLocEntries.end();
        I != E; ++I, ++index) {
     DotDebugLocEntry &Entry = *I;
@@ -2431,7 +2481,7 @@ void DwarfDebug::emitDebugRanges() {
   Asm->OutStreamer.SwitchSection(
     Asm->getObjFileLowering().getDwarfRangesSection());
   unsigned char Size = Asm->getDataLayout().getPointerSize();
-  for (SmallVector<const MCSymbol *, 8>::iterator
+  for (SmallVectorImpl<const MCSymbol *>::iterator
          I = DebugRangeSymbols.begin(), E = DebugRangeSymbols.end();
        I != E; ++I) {
     if (*I)
@@ -2489,13 +2539,13 @@ void DwarfDebug::emitDebugInlineInfo() {
   Asm->OutStreamer.AddComment("Address Size (in bytes)");
   Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
 
-  for (SmallVector<const MDNode *, 4>::iterator I = InlinedSPNodes.begin(),
+  for (SmallVectorImpl<const MDNode *>::iterator I = InlinedSPNodes.begin(),
          E = InlinedSPNodes.end(); I != E; ++I) {
 
     const MDNode *Node = *I;
     DenseMap<const MDNode *, SmallVector<InlineInfoLabels, 4> >::iterator II
       = InlineInfo.find(Node);
-    SmallVector<InlineInfoLabels, 4> &Labels = II->second;
+    SmallVectorImpl<InlineInfoLabels> &Labels = II->second;
     DISubprogram SP(Node);
     StringRef LName = SP.getLinkageName();
     StringRef Name = SP.getName();
@@ -2514,7 +2564,7 @@ void DwarfDebug::emitDebugInlineInfo() {
                            DwarfStrSectionSym);
     Asm->EmitULEB128(Labels.size(), "Inline count");
 
-    for (SmallVector<InlineInfoLabels, 4>::iterator LI = Labels.begin(),
+    for (SmallVectorImpl<InlineInfoLabels>::iterator LI = Labels.begin(),
            LE = Labels.end(); LI != LE; ++LI) {
       if (Asm->isVerbose()) Asm->OutStreamer.AddComment("DIE offset");
       Asm->EmitInt32(LI->second->getOffset());
@@ -2549,9 +2599,14 @@ CompileUnit *DwarfDebug::constructSkeletonCU(const MDNode *N) {
   // This should be a unique identifier when we want to build .dwp files.
   NewCU->addUInt(Die, dwarf::DW_AT_GNU_dwo_id, dwarf::DW_FORM_data8, 0);
 
-  // FIXME: The addr base should be relative for each compile unit, however,
-  // this one is going to be 0 anyhow.
-  NewCU->addUInt(Die, dwarf::DW_AT_GNU_addr_base, dwarf::DW_FORM_sec_offset, 0);
+  // Relocate to the beginning of the addr_base section, else 0 for the
+  // beginning of the one for this compile unit.
+  if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
+    NewCU->addLabel(Die, dwarf::DW_AT_GNU_addr_base, dwarf::DW_FORM_sec_offset,
+                    DwarfAddrSectionSym);
+  else
+    NewCU->addUInt(Die, dwarf::DW_AT_GNU_addr_base,
+                   dwarf::DW_FORM_sec_offset, 0);
 
   // 2.17.1 requires that we use DW_AT_low_pc for a single entry point
   // into an entity. We're using 0, or a NULL label for this.
@@ -2559,6 +2614,7 @@ CompileUnit *DwarfDebug::constructSkeletonCU(const MDNode *N) {
 
   // DW_AT_stmt_list is a offset of line number information for this
   // compile unit in debug_line section.
+  // FIXME: Should handle multiple compile units.
   if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
     NewCU->addLabel(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_sec_offset,
                     DwarfLineSectionSym);
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 7b56815040..24f758dda9 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -274,6 +274,10 @@ public:
 
   /// \brief Returns the address pool.
   AddrPool *getAddrPool() { return &AddressPool; }
+
+  /// \brief for a given compile unit DIE, returns offset from beginning of
+  /// debug info.
+  unsigned getCUOffset(DIE *Die);
 };
 
 /// \brief Collects and handles dwarf debug information.
@@ -305,7 +309,9 @@ class DwarfDebug {
   // A list of all the unique abbreviations in use.
   std::vector<DIEAbbrev *> Abbreviations;
 
-  // Source id map, i.e. pair of source filename and directory,
+  // Stores the current file ID for a given compile unit.
+  DenseMap <unsigned, unsigned> FileIDCUMap;
+  // Source id map, i.e. CUID, source filename and directory,
   // separated by a zero byte, mapped to a unique id.
   StringMap<unsigned, BumpPtrAllocator&> SourceIdMap;
 
@@ -386,7 +392,7 @@ class DwarfDebug {
   // section offsets and are created by EmitSectionLabels.
   MCSymbol *DwarfInfoSectionSym, *DwarfAbbrevSectionSym;
   MCSymbol *DwarfStrSectionSym, *TextSectionSym, *DwarfDebugRangeSectionSym;
-  MCSymbol *DwarfDebugLocSectionSym, *DwarfLineSectionSym;
+  MCSymbol *DwarfDebugLocSectionSym, *DwarfLineSectionSym, *DwarfAddrSectionSym;
   MCSymbol *FunctionBeginSym, *FunctionEndSym;
   MCSymbol *DwarfAbbrevDWOSectionSym, *DwarfStrDWOSectionSym;
 
@@ -427,6 +433,10 @@ class DwarfDebug {
   // Holder for the skeleton information.
   DwarfUnits SkeletonHolder;
 
+  typedef SmallVector<std::pair<const MDNode *, const MDNode *>, 32>
+    ImportedEntityMap;
+  ImportedEntityMap ScopesWithImportedEntities;
+
 private:
 
   void addScopeVariable(LexicalScope *LS, DbgVariable *Var);
@@ -549,6 +559,18 @@ private:
   /// \brief Construct subprogram DIE.
   void constructSubprogramDIE(CompileUnit *TheCU, const MDNode *N);
 
+  /// \brief Construct import_module DIE.
+  void constructImportedModuleDIE(CompileUnit *TheCU, const MDNode *N);
+
+  /// \brief Construct import_module DIE.
+  void constructImportedModuleDIE(CompileUnit *TheCU, const MDNode *N,
+                                  DIE *Context);
+
+  /// \brief Construct import_module DIE.
+  void constructImportedModuleDIE(CompileUnit *TheCU,
+                                  const DIImportedModule &Module,
+                                  DIE *Context);
+
   /// \brief Register a source line with debug info. Returns the unique
   /// label that was emitted and which provides correspondence to the
   /// source line list.
@@ -596,14 +618,6 @@ public:
   DwarfDebug(AsmPrinter *A, Module *M);
   ~DwarfDebug();
 
-  /// \brief Collect debug info from named mdnodes such as llvm.dbg.enum
-  /// and llvm.dbg.ty
-  void collectInfoFromNamedMDNodes(const Module *M);
-
-  /// \brief Collect debug info using DebugInfoFinder.
-  /// FIXME - Remove this when DragonEgg switches to DIBuilder.
-  bool collectLegacyDebugInfo(const Module *M);
-
   /// \brief Emit all Dwarf sections that should come prior to the
   /// content.
   void beginModule();
@@ -626,7 +640,8 @@ public:
   /// \brief Look up the source id with the given directory and source file
   /// names. If none currently exists, create a new id and insert it in the
   /// SourceIds map.
-  unsigned getOrCreateSourceID(StringRef DirName, StringRef FullName);
+  unsigned getOrCreateSourceID(StringRef DirName, StringRef FullName,
+                               unsigned CUID);
 
   /// \brief Recursively Emits a debug information entry.
   void emitDIE(DIE *Die, std::vector<DIEAbbrev *> *Abbrevs);
diff --git a/lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp b/lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp
new file mode 100644
index 0000000000..a8fb66dcf1
--- /dev/null
+++ b/lib/CodeGen/AsmPrinter/ErlangGCPrinter.cpp
@@ -0,0 +1,120 @@
+//===-- ErlangGCPrinter.cpp - Erlang/OTP frametable emitter -----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the compiler plugin that is used in order to emit
+// garbage collection information in a convenient layout for parsing and
+// loading in the Erlang/OTP runtime.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/GCs.h"
+#include "llvm/CodeGen/GCMetadataPrinter.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Metadata.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCSectionELF.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/Target/TargetMachine.h"
+
+using namespace llvm;
+
+namespace {
+
+  class ErlangGCPrinter : public GCMetadataPrinter {
+  public:
+    void beginAssembly(AsmPrinter &AP);
+    void finishAssembly(AsmPrinter &AP);
+  };
+
+}
+
+static GCMetadataPrinterRegistry::Add<ErlangGCPrinter>
+X("erlang", "erlang-compatible garbage collector");
+
+void llvm::linkErlangGCPrinter() { }
+
+void ErlangGCPrinter::beginAssembly(AsmPrinter &AP) { }
+
+void ErlangGCPrinter::finishAssembly(AsmPrinter &AP) {
+  MCStreamer &OS = AP.OutStreamer;
+  unsigned IntPtrSize = AP.TM.getDataLayout()->getPointerSize();
+
+  // Put this in a custom .note section.
+  AP.OutStreamer.SwitchSection(AP.getObjFileLowering().getContext()
+    .getELFSection(".note.gc", ELF::SHT_PROGBITS, 0,
+                   SectionKind::getDataRel()));
+
+  // For each function...
+  for (iterator FI = begin(), FE = end(); FI != FE; ++FI) {
+    GCFunctionInfo &MD = **FI;
+
+    /** A compact GC layout. Emit this data structure:
+     *
+     * struct {
+     *   int16_t PointCount;
+     *   void *SafePointAddress[PointCount];
+     *   int16_t StackFrameSize; (in words)
+     *   int16_t StackArity;
+     *   int16_t LiveCount;
+     *   int16_t LiveOffsets[LiveCount];
+     * } __gcmap_<FUNCTIONNAME>;
+     **/
+
+    // Align to address width.
+    AP.EmitAlignment(IntPtrSize == 4 ? 2 : 3);
+
+    // Emit PointCount.
+    OS.AddComment("safe point count");
+    AP.EmitInt16(MD.size());
+
+    // And each safe point...
+    for (GCFunctionInfo::iterator PI = MD.begin(), PE = MD.end(); PI != PE;
+         ++PI) {
+      // Emit the address of the safe point.
+      OS.AddComment("safe point address");
+      MCSymbol *Label = PI->Label;
+      AP.EmitLabelPlusOffset(Label/*Hi*/, 0/*Offset*/, 4/*Size*/);
+    }
+
+    // Stack information never change in safe points! Only print info from the
+    // first call-site.
+    GCFunctionInfo::iterator PI = MD.begin();
+
+    // Emit the stack frame size.
+    OS.AddComment("stack frame size (in words)");
+    AP.EmitInt16(MD.getFrameSize() / IntPtrSize);
+
+    // Emit stack arity, i.e. the number of stacked arguments.
+    unsigned RegisteredArgs = IntPtrSize == 4 ? 5 : 6;
+    unsigned StackArity = MD.getFunction().arg_size() > RegisteredArgs ?
+                          MD.getFunction().arg_size() - RegisteredArgs : 0;
+    OS.AddComment("stack arity");
+    AP.EmitInt16(StackArity);
+
+    // Emit the number of live roots in the function.
+    OS.AddComment("live root count");
+    AP.EmitInt16(MD.live_size(PI));
+
+    // And for each live root...
+    for (GCFunctionInfo::live_iterator LI = MD.live_begin(PI),
+                                       LE = MD.live_end(PI);
+                                       LI != LE; ++LI) {
+      // Emit live root's offset within the stack frame.
+      OS.AddComment("stack index (offset / wordsize)");
+      AP.EmitInt16(LI->StackOffset / IntPtrSize);
+    }
+  }
+}