Merge commit '1ad9253c9d34ccbce3e7e4ea5d87c266cbf93410'

deplib features commented out due to removal upstream;
will add back as a localmod

Conflicts:
	include/llvm/ADT/Triple.h
	include/llvm/MC/MCAssembler.h
	include/llvm/Target/TargetFrameLowering.h
	lib/CodeGen/AsmPrinter/DwarfDebug.cpp
	lib/CodeGen/AsmPrinter/DwarfDebug.h
	lib/CodeGen/BranchFolding.cpp
	lib/LLVMBuild.txt
	lib/Linker/LinkArchives.cpp
	lib/MC/MCAssembler.cpp
	lib/MC/MCELFStreamer.cpp
	lib/Makefile
	lib/Target/ARM/ARMExpandPseudoInsts.cpp
	lib/Target/ARM/ARMFrameLowering.cpp
	lib/Target/ARM/ARMISelLowering.cpp
	lib/Target/ARM/ARMSubtarget.h
	lib/Target/ARM/ARMTargetObjectFile.cpp
	lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
	lib/Target/Mips/MipsInstrFPU.td
	lib/Target/Mips/MipsInstrInfo.td
	lib/Target/X86/X86CodeEmitter.cpp
	lib/Target/X86/X86Subtarget.h
	lib/VMCore/Module.cpp
	test/MC/MachO/ARM/nop-armv4-padding.s
	tools/Makefile
	tools/llc/llc.cpp
	tools/lto/LTOModule.cpp
	tools/lto/lto.cpp

1 files changed, 328 insertions, 254 deletions

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 1a9deb6641..ad18024559 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -16,34 +16,34 @@
 #include "DIE.h"
 #include "DwarfAccelTable.h"
 #include "DwarfCompileUnit.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/Constants.h"
-#include "llvm/DebugInfo.h"
 #include "llvm/DIBuilder.h"
-#include "llvm/Module.h"
+#include "llvm/DataLayout.h"
+#include "llvm/DebugInfo.h"
 #include "llvm/Instructions.h"
-#include "llvm/CodeGen/MachineFunction.h"
-#include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCSection.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbol.h"
-#include "llvm/DataLayout.h"
-#include "llvm/Target/TargetFrameLowering.h"
-#include "llvm/Target/TargetLoweringObjectFile.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetRegisterInfo.h"
-#include "llvm/Target/TargetOptions.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/StringExtras.h"
-#include "llvm/ADT/Triple.h"
+#include "llvm/Module.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/ValueHandle.h"
 #include "llvm/Support/FormattedStream.h"
-#include "llvm/Support/Timer.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/Timer.h"
+#include "llvm/Support/ValueHandle.h"
+#include "llvm/Target/TargetFrameLowering.h"
+#include "llvm/Target/TargetLoweringObjectFile.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Target/TargetRegisterInfo.h"
 using namespace llvm;
 
 static cl::opt<bool> DisableDebugInfoPrinting("disable-debug-info-print",
@@ -78,8 +78,8 @@ static cl::opt<DefaultOnOff> DarwinGDBCompat("darwin-gdb-compat", cl::Hidden,
                 clEnumValEnd),
      cl::init(Default));
 
-static cl::opt<DefaultOnOff> DwarfFission("dwarf-fission", cl::Hidden,
-     cl::desc("Output prototype dwarf fission."),
+static cl::opt<DefaultOnOff> SplitDwarf("split-dwarf", cl::Hidden,
+     cl::desc("Output prototype dwarf split debug info."),
      cl::values(
                 clEnumVal(Default, "Default for platform"),
                 clEnumVal(Enable, "Enabled"),
@@ -94,8 +94,8 @@ namespace {
 
 //===----------------------------------------------------------------------===//
 
-/// Configuration values for initial hash set sizes (log2).
-///
+// Configuration values for initial hash set sizes (log2).
+//
 static const unsigned InitAbbreviationsSetSize = 9; // log2(512)
 
 namespace llvm {
@@ -156,7 +156,9 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   : Asm(A), MMI(Asm->MMI), FirstCU(0),
     AbbreviationsSet(InitAbbreviationsSetSize),
     SourceIdMap(DIEValueAllocator), StringPool(DIEValueAllocator),
-    PrevLabel(NULL) {
+    PrevLabel(NULL), GlobalCUIndexCount(0),
+    InfoHolder(A, &AbbreviationsSet, &Abbreviations),
+    SkeletonCU(0), SkeletonHolder(A, &AbbreviationsSet, &Abbreviations) {
   NextStringPoolNumber = 0;
 
   DwarfInfoSectionSym = DwarfAbbrevSectionSym = 0;
@@ -183,10 +185,10 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
   } else
     HasDwarfAccelTables = DwarfAccelTables == Enable ? true : false;
 
-  if (DwarfFission == Default)
-    HasDwarfFission = false;
+  if (SplitDwarf == Default)
+    HasSplitDwarf = false;
   else
-    HasDwarfFission = DwarfFission == Enable ? true : false;
+    HasSplitDwarf = SplitDwarf == Enable ? true : false;
 
   {
     NamedRegionTimer T(DbgTimerName, DWARFGroupName, TimePassesIsEnabled);
@@ -196,8 +198,8 @@ DwarfDebug::DwarfDebug(AsmPrinter *A, Module *M)
 DwarfDebug::~DwarfDebug() {
 }
 
-/// emitSectionSym - Switch to the specified MCSection and emit an assembler
-/// temporary label to it if SymbolStem is specified.
+// Switch to the specified MCSection and emit an assembler
+// temporary label to it if SymbolStem is specified.
 static MCSymbol *emitSectionSym(AsmPrinter *Asm, const MCSection *Section,
                                 const char *SymbolStem = 0) {
   Asm->OutStreamer.SwitchSection(Section);
@@ -220,32 +222,32 @@ MCSymbol *DwarfDebug::getStringPoolEntry(StringRef Str) {
   return Entry.first = Asm->GetTempSymbol("string", Entry.second);
 }
 
-/// assignAbbrevNumber - Define a unique number for the abbreviation.
-///
-void DwarfDebug::assignAbbrevNumber(DIEAbbrev &Abbrev) {
+// Define a unique number for the abbreviation.
+//
+void DwarfUnits::assignAbbrevNumber(DIEAbbrev &Abbrev) {
   // Profile the node so that we can make it unique.
   FoldingSetNodeID ID;
   Abbrev.Profile(ID);
 
   // Check the set for priors.
-  DIEAbbrev *InSet = AbbreviationsSet.GetOrInsertNode(&Abbrev);
+  DIEAbbrev *InSet = AbbreviationsSet->GetOrInsertNode(&Abbrev);
 
   // If it's newly added.
   if (InSet == &Abbrev) {
     // Add to abbreviation list.
-    Abbreviations.push_back(&Abbrev);
+    Abbreviations->push_back(&Abbrev);
 
     // Assign the vector position + 1 as its number.
-    Abbrev.setNumber(Abbreviations.size());
+    Abbrev.setNumber(Abbreviations->size());
   } else {
     // Assign existing abbreviation number.
     Abbrev.setNumber(InSet->getNumber());
   }
 }
 
-/// getRealLinkageName - If special LLVM prefix that is used to inform the asm
-/// printer to not emit usual symbol prefix before the symbol name is used then
-/// return linkage name after skipping this special LLVM prefix.
+// If special LLVM prefix that is used to inform the asm
+// printer to not emit usual symbol prefix before the symbol name is used then
+// return linkage name after skipping this special LLVM prefix.
 static StringRef getRealLinkageName(StringRef LinkageName) {
   char One = '\1';
   if (LinkageName.startswith(StringRef(&One, 1)))
@@ -310,10 +312,9 @@ static void addSubprogramNames(CompileUnit *TheCU, DISubprogram SP,
   }
 }
 
-/// updateSubprogramScopeDIE - 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.
+// Find DIE for the given subprogram and attach appropriate DW_AT_low_pc
+// and DW_AT_high_pc attributes. If there are global variables in this
+// scope then create and insert DIEs for these variables.
 DIE *DwarfDebug::updateSubprogramScopeDIE(CompileUnit *SPCU,
                                           const MDNode *SPNode) {
   DIE *SPDie = SPCU->getDIE(SPNode);
@@ -383,8 +384,8 @@ DIE *DwarfDebug::updateSubprogramScopeDIE(CompileUnit *SPCU,
   return SPDie;
 }
 
-/// constructLexicalScope - Construct new DW_TAG_lexical_block
-/// for this scope and attach DW_AT_low_pc/DW_AT_high_pc labels.
+// Construct new DW_TAG_lexical_block for this scope and attach
+// DW_AT_low_pc/DW_AT_high_pc labels.
 DIE *DwarfDebug::constructLexicalScopeDIE(CompileUnit *TheCU,
                                           LexicalScope *Scope) {
   DIE *ScopeDIE = new DIE(dwarf::DW_TAG_lexical_block);
@@ -427,9 +428,8 @@ DIE *DwarfDebug::constructLexicalScopeDIE(CompileUnit *TheCU,
   return ScopeDIE;
 }
 
-/// constructInlinedScopeDIE - This scope represents inlined body of
-/// a function. Construct DIE to represent this concrete inlined copy
-/// of the function.
+// This scope represents inlined body of a function. Construct DIE to
+// represent this concrete inlined copy of the function.
 DIE *DwarfDebug::constructInlinedScopeDIE(CompileUnit *TheCU,
                                           LexicalScope *Scope) {
   const SmallVector<InsnRange, 4> &Ranges = Scope->getRanges();
@@ -511,7 +511,7 @@ DIE *DwarfDebug::constructInlinedScopeDIE(CompileUnit *TheCU,
   return ScopeDIE;
 }
 
-/// constructScopeDIE - Construct a DIE for this scope.
+// Construct a DIE for this scope.
 DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
   if (!Scope || !Scope->getScopeNode())
     return NULL;
@@ -580,13 +580,12 @@ DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
   return ScopeDIE;
 }
 
-/// getOrCreateSourceID - 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. This can update DirectoryNames and SourceFileNames
-/// maps as well.
+// 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. This can update DirectoryNames and SourceFileNames maps
+// as well.
 unsigned DwarfDebug::getOrCreateSourceID(StringRef FileName,
-                                         StringRef DirName,
-                                         StringRef Extra) { // @LOCALMOD
+                                         StringRef DirName) {
   // If FE did not provide a file name, then assume stdin.
   if (FileName.empty())
     return getOrCreateSourceID("<stdin>", StringRef());
@@ -602,9 +601,6 @@ unsigned DwarfDebug::getOrCreateSourceID(StringRef FileName,
   NamePair += DirName;
   NamePair += '\0'; // Zero bytes are not allowed in paths.
   NamePair += FileName;
-  // @LOCALMOD
-  NamePair += '\0'; // Zero bytes are not allowed in paths.
-  NamePair += Extra;
 
   StringMapEntry<unsigned> &Ent = SourceIdMap.GetOrCreateValue(NamePair, SrcId);
   if (Ent.getValue() != SrcId)
@@ -616,47 +612,18 @@ unsigned DwarfDebug::getOrCreateSourceID(StringRef FileName,
   return SrcId;
 }
 
-// @LOCALMOD-BEGIN
-// A special version of GetOrCreateSourceID for CompileUnits.
-// It is possible that with bitcode linking, we end up with distinct
-// compile units based on the same source file.
-// E.g., compile foo.c with -DMACRO1 to foo1.bc, then compile
-// foo.c again with -DMACRO2 to foo2.bc and link.
-// We use additional information to form a unique ID in that case.
-unsigned DwarfDebug::getOrCreateCompileUnitID(StringRef Filename,
-                                              StringRef Dirname,
-                                              const MDNode *N) {
-  std::string DIUnitStr;
-  raw_string_ostream ostr(DIUnitStr);
-
-  // Using information from the compile unit (N)'s getEnumTypes(),
-  // getRetainedTypes(), getSubprograms(), getGlobalVariables()
-  // could be pretty expensive.
-  // Cheat and use the MDNode's address as an additional identifying factor.
-  // constructCompileUnit() is only called once per compile unit.
-  ostr << static_cast<const void*>(N);
-  return getOrCreateSourceID(Filename, Dirname, ostr.str());
-}
-// @LOCALMOD-END
-
-/// constructCompileUnit - Create new CompileUnit for the given
-/// metadata node with tag DW_TAG_compile_unit.
+// Create new CompileUnit for the given metadata node with tag DW_TAG_compile_unit.
 CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
   DICompileUnit DIUnit(N);
   StringRef FN = DIUnit.getFilename();
   CompilationDir = DIUnit.getDirectory();
-  // @LOCALMOD-BEGIN
-  unsigned ID;
-  if (Triple(Asm->TM.getTargetTriple()).isOSNaCl()) {
-    ID = getOrCreateCompileUnitID(FN, CompilationDir, N);
-  } else {
-    ID = getOrCreateSourceID(FN, CompilationDir);
-  }
-  // @LOCALMOD-END
+  // 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(ID, DIUnit.getLanguage(), Die,
-                                       Asm, this);
+  CompileUnit *NewCU = new CompileUnit(GlobalCUIndexCount++,
+                                       DIUnit.getLanguage(), Die, Asm, this);
   NewCU->addString(Die, dwarf::DW_AT_producer, DIUnit.getProducer());
   NewCU->addUInt(Die, dwarf::DW_AT_language, dwarf::DW_FORM_data2,
                  DIUnit.getLanguage());
@@ -687,11 +654,16 @@ CompileUnit *DwarfDebug::constructCompileUnit(const MDNode *N) {
 
   if (!FirstCU)
     FirstCU = NewCU;
+  if (useSplitDwarf() && !SkeletonCU)
+    SkeletonCU = constructSkeletonCU(N);
+
+  InfoHolder.addUnit(NewCU);
+
   CUMap.insert(std::make_pair(N, NewCU));
   return NewCU;
 }
 
-/// construct SubprogramDIE - Construct subprogram DIE.
+// Construct subprogram DIE.
 void DwarfDebug::constructSubprogramDIE(CompileUnit *TheCU,
                                         const MDNode *N) {
   CompileUnit *&CURef = SPMap[N];
@@ -716,8 +688,7 @@ void DwarfDebug::constructSubprogramDIE(CompileUnit *TheCU,
   return;
 }
 
-/// collectInfoFromNamedMDNodes - Collect debug info from named mdnodes such
-/// as llvm.dbg.enum and llvm.dbg.ty
+// 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) {
@@ -748,8 +719,8 @@ void DwarfDebug::collectInfoFromNamedMDNodes(const Module *M) {
     }
 }
 
-/// collectLegacyDebugInfo - Collect debug info using DebugInfoFinder.
-/// FIXME - Remove this when dragon-egg and llvm-gcc switch to DIBuilder.
+// Collect debug info using DebugInfoFinder.
+// FIXME - Remove this when dragonegg switches to DIBuilder.
 bool DwarfDebug::collectLegacyDebugInfo(const Module *M) {
   DebugInfoFinder DbgFinder;
   DbgFinder.processModule(*M);
@@ -770,6 +741,7 @@ bool DwarfDebug::collectLegacyDebugInfo(const Module *M) {
   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) {
@@ -789,9 +761,9 @@ bool DwarfDebug::collectLegacyDebugInfo(const Module *M) {
   return HasDebugInfo;
 }
 
-/// beginModule - Emit all Dwarf sections that should come prior to the
-/// content. Create global DIEs and emit initial debug info sections.
-/// This is invoked by the target AsmPrinter.
+// Emit all Dwarf sections that should come prior to the content. Create
+// global DIEs and emit initial debug info sections. This is invoked by
+// the target AsmPrinter.
 void DwarfDebug::beginModule() {
   if (DisableDebugInfoPrinting)
     return;
@@ -834,12 +806,12 @@ void DwarfDebug::beginModule() {
 void DwarfDebug::computeInlinedDIEs() {
   // Attach DW_AT_inline attribute with inlined subprogram DIEs.
   for (SmallPtrSet<DIE *, 4>::iterator AI = InlinedSubprogramDIEs.begin(),
-	 AE = InlinedSubprogramDIEs.end(); AI != AE; ++AI) {
+         AE = InlinedSubprogramDIEs.end(); AI != AE; ++AI) {
     DIE *ISP = *AI;
     FirstCU->addUInt(ISP, dwarf::DW_AT_inline, 0, dwarf::DW_INL_inlined);
   }
   for (DenseMap<const MDNode *, DIE *>::iterator AI = AbstractSPDies.begin(),
-	 AE = AbstractSPDies.end(); AI != AE; ++AI) {
+         AE = AbstractSPDies.end(); AI != AE; ++AI) {
     DIE *ISP = AI->second;
     if (InlinedSubprogramDIEs.count(ISP))
       continue;
@@ -857,30 +829,30 @@ void DwarfDebug::collectDeadVariables() {
       DICompileUnit TheCU(CU_Nodes->getOperand(i));
       DIArray Subprograms = TheCU.getSubprograms();
       for (unsigned i = 0, e = Subprograms.getNumElements(); i != e; ++i) {
-	DISubprogram SP(Subprograms.getElement(i));
-	if (ProcessedSPNodes.count(SP) != 0) continue;
-	if (!SP.Verify()) continue;
-	if (!SP.isDefinition()) continue;
-	DIArray Variables = SP.getVariables();
-	if (Variables.getNumElements() == 0) continue;
-
-	LexicalScope *Scope =
-	  new LexicalScope(NULL, DIDescriptor(SP), NULL, false);
-	DeadFnScopeMap[SP] = Scope;
-
-	// Construct subprogram DIE and add variables DIEs.
-	CompileUnit *SPCU = CUMap.lookup(TheCU);
-	assert(SPCU && "Unable to find Compile Unit!");
-	constructSubprogramDIE(SPCU, SP);
-	DIE *ScopeDIE = SPCU->getDIE(SP);
-	for (unsigned vi = 0, ve = Variables.getNumElements(); vi != ve; ++vi) {
-	  DIVariable DV(Variables.getElement(vi));
-	  if (!DV.Verify()) continue;
-	  DbgVariable *NewVar = new DbgVariable(DV, NULL);
-	  if (DIE *VariableDIE =
-	      SPCU->constructVariableDIE(NewVar, Scope->isAbstractScope()))
-	    ScopeDIE->addChild(VariableDIE);
-	}
+        DISubprogram SP(Subprograms.getElement(i));
+        if (ProcessedSPNodes.count(SP) != 0) continue;
+        if (!SP.Verify()) continue;
+        if (!SP.isDefinition()) continue;
+        DIArray Variables = SP.getVariables();
+        if (Variables.getNumElements() == 0) continue;
+
+        LexicalScope *Scope =
+          new LexicalScope(NULL, DIDescriptor(SP), NULL, false);
+        DeadFnScopeMap[SP] = Scope;
+
+        // Construct subprogram DIE and add variables DIEs.
+        CompileUnit *SPCU = CUMap.lookup(TheCU);
+        assert(SPCU && "Unable to find Compile Unit!");
+        constructSubprogramDIE(SPCU, SP);
+        DIE *ScopeDIE = SPCU->getDIE(SP);
+        for (unsigned vi = 0, ve = Variables.getNumElements(); vi != ve; ++vi) {
+          DIVariable DV(Variables.getElement(vi));
+          if (!DV.Verify()) continue;
+          DbgVariable *NewVar = new DbgVariable(DV, NULL);
+          if (DIE *VariableDIE =
+              SPCU->constructVariableDIE(NewVar, Scope->isAbstractScope()))
+            ScopeDIE->addChild(VariableDIE);
+        }
       }
     }
   }
@@ -897,13 +869,15 @@ void DwarfDebug::finalizeModuleInfo() {
   // Emit DW_AT_containing_type attribute to connect types with their
   // vtable holding type.
   for (DenseMap<const MDNode *, CompileUnit *>::iterator CUI = CUMap.begin(),
-	 CUE = CUMap.end(); CUI != CUE; ++CUI) {
+         CUE = CUMap.end(); CUI != CUE; ++CUI) {
     CompileUnit *TheCU = CUI->second;
     TheCU->constructContainingTypeDIEs();
   }
 
    // Compute DIE offsets and sizes.
-  computeSizeAndOffsets();
+  InfoHolder.computeSizeAndOffsets();
+  if (useSplitDwarf())
+    SkeletonHolder.computeSizeAndOffsets();
 }
 
 void DwarfDebug::endSections() {
@@ -920,8 +894,7 @@ void DwarfDebug::endSections() {
   }
 }
 
-/// endModule - Emit all Dwarf sections that should come after the content.
-///
+// Emit all Dwarf sections that should come after the content.
 void DwarfDebug::endModule() {
 
   if (!FirstCU) return;
@@ -936,11 +909,61 @@ void DwarfDebug::endModule() {
   // Emit initial sections.
   emitSectionLabels();
 
-  // Emit all the DIEs into a debug info section
-  emitDebugInfo();
+  if (!useSplitDwarf()) {
+    // Emit all the DIEs into a debug info section.
+    emitDebugInfo();
+
+    // Corresponding abbreviations into a abbrev section.
+    emitAbbreviations();
+
+    // Emit info into a debug loc section.
+    emitDebugLoc();
+
+    // Emit info into a debug aranges section.
+    emitDebugARanges();
+
+    // Emit info into a debug ranges section.
+    emitDebugRanges();
 
-  // Corresponding abbreviations into a abbrev section.
-  emitAbbreviations();
+    // Emit info into a debug macinfo section.
+    emitDebugMacInfo();
+
+    // Emit inline info.
+    // TODO: When we don't need the option anymore we
+    // can remove all of the code that this section
+    // depends upon.
+    if (useDarwinGDBCompat())
+      emitDebugInlineInfo();
+  } else {
+    // TODO: Fill this in for Fission sections and separate
+    // out information into new sections.
+
+    // Emit the debug info section and compile units.
+    emitDebugInfo();
+    emitDebugInfoDWO();
+
+    // Corresponding abbreviations into a abbrev section.
+    emitAbbreviations();
+
+    // Emit info into a debug loc section.
+    emitDebugLoc();
+
+    // Emit info into a debug aranges section.
+    emitDebugARanges();
+
+    // Emit info into a debug ranges section.
+    emitDebugRanges();
+
+    // Emit info into a debug macinfo section.
+    emitDebugMacInfo();
+
+    // Emit inline info.
+    // TODO: When we don't need the option anymore we
+    // can remove all of the code that this section
+    // depends upon.
+    if (useDarwinGDBCompat())
+      emitDebugInlineInfo();
+  }
 
   // Emit info into the dwarf accelerator table sections.
   if (useDwarfAccelTables()) {
@@ -956,26 +979,7 @@ void DwarfDebug::endModule() {
   if (useDarwinGDBCompat())
     emitDebugPubTypes();
 
-  // Emit info into a debug loc section.
-  emitDebugLoc();
-
-  // Emit info into a debug aranges section.
-  emitDebugARanges();
-
-  // Emit info into a debug ranges section.
-  emitDebugRanges();
-
-  // Emit info into a debug macinfo section.
-  emitDebugMacInfo();
-
-  // Emit inline info.
-  // TODO: When we don't need the option anymore we
-  // can remove all of the code that this section
-  // depends upon.
-  if (useDarwinGDBCompat())
-    emitDebugInlineInfo();
-
-  // Emit info into a debug str section.
+  // Finally emit string information into a string table.
   emitDebugStr();
 
   // clean up.
@@ -983,10 +987,15 @@ void DwarfDebug::endModule() {
   for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
          E = CUMap.end(); I != E; ++I)
     delete I->second;
-  FirstCU = NULL;  // Reset for the next Module, if any.
+
+  delete SkeletonCU;
+
+  // Reset these for the next Module if we have one.
+  FirstCU = NULL;
+  SkeletonCU = NULL;
 }
 
-/// findAbstractVariable - Find abstract variable, if any, associated with Var.
+// Find abstract variable, if any, associated with Var.
 DbgVariable *DwarfDebug::findAbstractVariable(DIVariable &DV,
                                               DebugLoc ScopeLoc) {
   LLVMContext &Ctx = DV->getContext();
@@ -1006,8 +1015,7 @@ DbgVariable *DwarfDebug::findAbstractVariable(DIVariable &DV,
   return AbsDbgVariable;
 }
 
-/// addCurrentFnArgument - If Var is a current function argument then add
-/// it to CurrentFnArguments list.
+// If Var is a current function argument then add it to CurrentFnArguments list.
 bool DwarfDebug::addCurrentFnArgument(const MachineFunction *MF,
                                       DbgVariable *Var, LexicalScope *Scope) {
   if (!LScopes.isCurrentFunctionScope(Scope))
@@ -1030,8 +1038,7 @@ bool DwarfDebug::addCurrentFnArgument(const MachineFunction *MF,
   return true;
 }
 
-/// collectVariableInfoFromMMITable - Collect variable information from
-/// side table maintained by MMI.
+// Collect variable information from side table maintained by MMI.
 void
 DwarfDebug::collectVariableInfoFromMMITable(const MachineFunction *MF,
                                    SmallPtrSet<const MDNode *, 16> &Processed) {
@@ -1060,8 +1067,8 @@ DwarfDebug::collectVariableInfoFromMMITable(const MachineFunction *MF,
   }
 }
 
-/// isDbgValueInDefinedReg - Return true if debug value, encoded by
-/// DBG_VALUE instruction, is in a defined reg.
+// Return true if debug value, encoded by DBG_VALUE instruction, is in a
+// defined reg.
 static bool isDbgValueInDefinedReg(const MachineInstr *MI) {
   assert(MI->isDebugValue() && "Invalid DBG_VALUE machine instruction!");
   return MI->getNumOperands() == 3 &&
@@ -1069,8 +1076,7 @@ static bool isDbgValueInDefinedReg(const MachineInstr *MI) {
          MI->getOperand(1).isImm() && MI->getOperand(1).getImm() == 0;
 }
 
-/// getDebugLocEntry - Get .debug_loc entry for the instruction range starting
-/// at MI.
+// Get .debug_loc entry for the instruction range starting at MI.
 static DotDebugLocEntry getDebugLocEntry(AsmPrinter *Asm,
                                          const MCSymbol *FLabel,
                                          const MCSymbol *SLabel,
@@ -1096,12 +1102,12 @@ static DotDebugLocEntry getDebugLocEntry(AsmPrinter *Asm,
   llvm_unreachable("Unexpected 3 operand DBG_VALUE instruction!");
 }
 
-/// collectVariableInfo - Find variables for each lexical scope.
+// Find variables for each lexical scope.
 void
 DwarfDebug::collectVariableInfo(const MachineFunction *MF,
                                 SmallPtrSet<const MDNode *, 16> &Processed) {
 
-  /// collection info from MMI table.
+  // collection info from MMI table.
   collectVariableInfoFromMMITable(MF, Processed);
 
   for (SmallVectorImpl<const MDNode*>::const_iterator
@@ -1207,19 +1213,19 @@ DwarfDebug::collectVariableInfo(const MachineFunction *MF,
   }
 }
 
-/// getLabelBeforeInsn - Return Label preceding the instruction.
+// Return Label preceding the instruction.
 const MCSymbol *DwarfDebug::getLabelBeforeInsn(const MachineInstr *MI) {
   MCSymbol *Label = LabelsBeforeInsn.lookup(MI);
   assert(Label && "Didn't insert label before instruction");
   return Label;
 }
 
-/// getLabelAfterInsn - Return Label immediately following the instruction.
+// Return Label immediately following the instruction.
 const MCSymbol *DwarfDebug::getLabelAfterInsn(const MachineInstr *MI) {
   return LabelsAfterInsn.lookup(MI);
 }
 
-/// beginInstruction - Process beginning of an instruction.
+// Process beginning of an instruction.
 void DwarfDebug::beginInstruction(const MachineInstr *MI) {
   // Check if source location changes, but ignore DBG_VALUE locations.
   if (!MI->isDebugValue()) {
@@ -1261,7 +1267,7 @@ void DwarfDebug::beginInstruction(const MachineInstr *MI) {
   I->second = PrevLabel;
 }
 
-/// endInstruction - Process end of an instruction.
+// Process end of an instruction.
 void DwarfDebug::endInstruction(const MachineInstr *MI) {
   // Don't create a new label after DBG_VALUE instructions.
   // They don't generate code.
@@ -1287,11 +1293,10 @@ void DwarfDebug::endInstruction(const MachineInstr *MI) {
   I->second = PrevLabel;
 }
 
-/// identifyScopeMarkers() -
-/// Each LexicalScope has first instruction and last instruction to mark
-/// beginning and end of a scope respectively. Create an inverse map that list
-/// scopes starts (and ends) with an instruction. One instruction may start (or
-/// end) multiple scopes. Ignore scopes that are not reachable.
+// Each LexicalScope has first instruction and last instruction to mark
+// beginning and end of a scope respectively. Create an inverse map that list
+// scopes starts (and ends) with an instruction. One instruction may start (or
+// end) multiple scopes. Ignore scopes that are not reachable.
 void DwarfDebug::identifyScopeMarkers() {
   SmallVector<LexicalScope *, 4> WorkList;
   WorkList.push_back(LScopes.getCurrentFunctionScope());
@@ -1320,15 +1325,15 @@ void DwarfDebug::identifyScopeMarkers() {
   }
 }
 
-/// getScopeNode - Get MDNode for DebugLoc's scope.
+// Get MDNode for DebugLoc's scope.
 static MDNode *getScopeNode(DebugLoc DL, const LLVMContext &Ctx) {
   if (MDNode *InlinedAt = DL.getInlinedAt(Ctx))
     return getScopeNode(DebugLoc::getFromDILocation(InlinedAt), Ctx);
   return DL.getScope(Ctx);
 }
 
-/// getFnDebugLoc - Walk up the scope chain of given debug loc and find
-/// line number info for the function.
+// Walk up the scope chain of given debug loc and find line number info
+// for the function.
 static DebugLoc getFnDebugLoc(DebugLoc DL, const LLVMContext &Ctx) {
   const MDNode *Scope = getScopeNode(DL, Ctx);
   DISubprogram SP = getDISubprogram(Scope);
@@ -1344,8 +1349,8 @@ static DebugLoc getFnDebugLoc(DebugLoc DL, const LLVMContext &Ctx) {
   return DebugLoc();
 }
 
-/// beginFunction - Gather pre-function debug information.  Assumes being
-/// emitted immediately after the function entry point.
+// Gather pre-function debug information.  Assumes being called immediately
+// after the function entry point has been emitted.
 void DwarfDebug::beginFunction(const MachineFunction *MF) {
   if (!MMI->hasDebugInfo()) return;
   LScopes.initialize(*MF);
@@ -1360,7 +1365,7 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
   assert(UserVariables.empty() && DbgValues.empty() && "Maps weren't cleaned");
 
   const TargetRegisterInfo *TRI = Asm->TM.getRegisterInfo();
-  /// LiveUserVar - Map physreg numbers to the MDNode they contain.
+  // LiveUserVar - Map physreg numbers to the MDNode they contain.
   std::vector<const MDNode*> LiveUserVar(TRI->getNumRegs());
 
   for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
@@ -1515,7 +1520,9 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
                                        MF->getFunction()->getContext());
     recordSourceLine(FnStartDL.getLine(), FnStartDL.getCol(),
                      FnStartDL.getScope(MF->getFunction()->getContext()),
-                     0);
+    // We'd like to list the prologue as "not statements" but GDB behaves
+    // poorly if we do that. Revisit this with caution/GDB (7.5+) testing.
+                     DWARF2_FLAG_IS_STMT);
   }
 }
 
@@ -1525,8 +1532,7 @@ void DwarfDebug::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
 //  Vars.push_back(Var);
 }
 
-/// endFunction - Gather and emit post-function debug information.
-///
+// Gather and emit post-function debug information.
 void DwarfDebug::endFunction(const MachineFunction *MF) {
   if (!MMI->hasDebugInfo() || LScopes.empty()) return;
 
@@ -1591,9 +1597,8 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
   PrevLabel = NULL;
 }
 
-/// recordSourceLine - Register a source line with debug info. Returns the
-/// unique label that was emitted and which provides correspondence to
-/// the source line list.
+// Register a source line with debug info. Returns the  unique label that was
+// emitted and which provides correspondence to the source line list.
 void DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, const MDNode *S,
                                   unsigned Flags) {
   StringRef Fn;
@@ -1634,10 +1639,9 @@ void DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, const MDNode *S,
 // Emit Methods
 //===----------------------------------------------------------------------===//
 
-/// computeSizeAndOffset - Compute the size and offset of a DIE.
-///
+// Compute the size and offset of a DIE.
 unsigned
-DwarfDebug::computeSizeAndOffset(DIE *Die, unsigned Offset) {
+DwarfUnits::computeSizeAndOffset(DIE *Die, unsigned Offset) {
   // Get the children.
   const std::vector<DIE *> &Children = Die->getChildren();
 
@@ -1646,7 +1650,7 @@ DwarfDebug::computeSizeAndOffset(DIE *Die, unsigned Offset) {
 
   // Get the abbreviation for this DIE.
   unsigned AbbrevNumber = Die->getAbbrevNumber();
-  const DIEAbbrev *Abbrev = Abbreviations[AbbrevNumber - 1];
+  const DIEAbbrev *Abbrev = Abbreviations->at(AbbrevNumber - 1);
 
   // Set DIE offset
   Die->setOffset(Offset);
@@ -1678,23 +1682,21 @@ DwarfDebug::computeSizeAndOffset(DIE *Die, unsigned Offset) {
   return Offset;
 }
 
-/// computeSizeAndOffsets - Compute the size and offset of all the DIEs.
-///
-void DwarfDebug::computeSizeAndOffsets() {
-  for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
-         E = CUMap.end(); I != E; ++I) {
-    // Compute size of compile unit header.
+// Compute the size and offset of all the DIEs.
+void DwarfUnits::computeSizeAndOffsets() {
+  for (SmallVector<CompileUnit *, 1>::iterator I = CUs.begin(),
+         E = CUs.end(); I != E; ++I) {
     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->second->getCUDie(), Offset);
+
+    computeSizeAndOffset((*I)->getCUDie(), Offset);
   }
 }
 
-/// emitSectionLabels - Emit initial Dwarf sections with a label at
-/// the start of each one.
+// Emit initial Dwarf sections with a label at the start of each one.
 void DwarfDebug::emitSectionLabels() {
   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
 
@@ -1723,8 +1725,7 @@ void DwarfDebug::emitSectionLabels() {
   emitSectionSym(Asm, TLOF.getDataSection());
 }
 
-/// emitDIE - Recursively emits a debug information entry.
-///
+// Recursively emits a debug information entry.
 void DwarfDebug::emitDIE(DIE *Die) {
   // Get the abbreviation for this DIE.
   unsigned AbbrevNumber = Die->getAbbrevNumber();
@@ -1813,12 +1814,8 @@ void DwarfDebug::emitDIE(DIE *Die) {
   }
 }
 
-/// emitDebugInfo - Emit the debug info section.
-///
-void DwarfDebug::emitDebugInfo() {
-  // Start debug info section.
-  Asm->OutStreamer.SwitchSection(
-                            Asm->getObjFileLowering().getDwarfInfoSection());
+void DwarfDebug::emitCompileUnits(const MCSection *Section) {
+  Asm->OutStreamer.SwitchSection(Section);
   for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
          E = CUMap.end(); I != E; ++I) {
     CompileUnit *TheCU = I->second;
@@ -1826,7 +1823,7 @@ void DwarfDebug::emitDebugInfo() {
 
     // Emit the compile units header.
     Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("info_begin",
-                                                  TheCU->getID()));
+                                                  TheCU->getUniqueID()));
 
     // Emit size of content not including length itself
     unsigned ContentSize = Die->getSize() +
@@ -1845,12 +1842,20 @@ void DwarfDebug::emitDebugInfo() {
     Asm->EmitInt8(Asm->getDataLayout().getPointerSize());
 
     emitDIE(Die);
-    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("info_end", TheCU->getID()));
+    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("info_end",
+                                                  TheCU->getUniqueID()));
   }
 }
 
-/// emitAbbreviations - Emit the abbreviation section.
-///
+// Emit the debug info section.
+void DwarfDebug::emitDebugInfo() {
+  if (!useSplitDwarf())
+    emitCompileUnits(Asm->getObjFileLowering().getDwarfInfoSection());
+  else
+    emitSkeletonCU(Asm->getObjFileLowering().getDwarfInfoSection());
+}
+
+// Emit the abbreviation section.
 void DwarfDebug::emitAbbreviations() {
   // Check to see if it is worth the effort.
   if (!Abbreviations.empty()) {
@@ -1879,9 +1884,7 @@ void DwarfDebug::emitAbbreviations() {
   }
 }
 
-/// emitEndOfLineMatrix - Emit the last address of the section and the end of
-/// the line matrix.
-///
+// Emit the last address of the section and the end of the line matrix.
 void DwarfDebug::emitEndOfLineMatrix(unsigned SectionEnd) {
   // Define last address of section.
   Asm->OutStreamer.AddComment("Extended Op");
@@ -1905,8 +1908,7 @@ void DwarfDebug::emitEndOfLineMatrix(unsigned SectionEnd) {
   Asm->EmitInt8(1);
 }
 
-/// emitAccelNames - Emit visible names into a hashed accelerator table
-/// section.
+// Emit visible names into a hashed accelerator table section.
 void DwarfDebug::emitAccelNames() {
   DwarfAccelTable AT(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
                                            dwarf::DW_FORM_data4));
@@ -1934,8 +1936,7 @@ void DwarfDebug::emitAccelNames() {
   AT.Emit(Asm, SectionBegin, this);
 }
 
-/// emitAccelObjC - Emit objective C classes and categories into a hashed
-/// accelerator table section.
+// Emit objective C classes and categories into a hashed accelerator table section.
 void DwarfDebug::emitAccelObjC() {
   DwarfAccelTable AT(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
                                            dwarf::DW_FORM_data4));
@@ -1963,8 +1964,7 @@ void DwarfDebug::emitAccelObjC() {
   AT.Emit(Asm, SectionBegin, this);
 }
 
-/// emitAccelNamespace - Emit namespace dies into a hashed accelerator
-/// table.
+// Emit namespace dies into a hashed accelerator table.
 void DwarfDebug::emitAccelNamespaces() {
   DwarfAccelTable AT(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
                                            dwarf::DW_FORM_data4));
@@ -1992,7 +1992,7 @@ void DwarfDebug::emitAccelNamespaces() {
   AT.Emit(Asm, SectionBegin, this);
 }
 
-/// emitAccelTypes() - Emit type dies into a hashed accelerator table.
+// Emit type dies into a hashed accelerator table.
 void DwarfDebug::emitAccelTypes() {
   std::vector<DwarfAccelTable::Atom> Atoms;
   Atoms.push_back(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
@@ -2036,22 +2036,25 @@ void DwarfDebug::emitDebugPubTypes() {
       Asm->getObjFileLowering().getDwarfPubTypesSection());
     Asm->OutStreamer.AddComment("Length of Public Types Info");
     Asm->EmitLabelDifference(
-      Asm->GetTempSymb