X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FIR%2FAsmWriter.cpp;h=ae0beba730b3d9ad97405478c3bae50a778b9777;hb=50b75d5804fe530a5985d25e0e19dffb166dfcc4;hp=14467137aae4d3491292184bc1b54f6192e4dab7;hpb=2d21b25393a461fbf8ab824889a6c56e1dd0b1cb;p=oota-llvm.git

diff --git a/lib/IR/AsmWriter.cpp b/lib/IR/AsmWriter.cpp
index 14467137aae..ae0beba730b 100644
--- a/lib/IR/AsmWriter.cpp
+++ b/lib/IR/AsmWriter.cpp
@@ -14,9 +14,9 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "AsmWriter.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/IR/AssemblyAnnotationWriter.h"
@@ -32,12 +32,14 @@
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/TypeFinder.h"
+#include "llvm/IR/UseListOrder.h"
 #include "llvm/IR/ValueSymbolTable.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Dwarf.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cctype>
 using namespace llvm;
@@ -49,6 +51,218 @@ AssemblyAnnotationWriter::~AssemblyAnnotationWriter() {}
 // Helper Functions
 //===----------------------------------------------------------------------===//
 
+namespace {
+struct OrderMap {
+  DenseMap<const Value *, std::pair<unsigned, bool>> IDs;
+
+  unsigned size() const { return IDs.size(); }
+  std::pair<unsigned, bool> &operator[](const Value *V) { return IDs[V]; }
+  std::pair<unsigned, bool> lookup(const Value *V) const {
+    return IDs.lookup(V);
+  }
+  void index(const Value *V) {
+    // Explicitly sequence get-size and insert-value operations to avoid UB.
+    unsigned ID = IDs.size() + 1;
+    IDs[V].first = ID;
+  }
+};
+}
+
+static void orderValue(const Value *V, OrderMap &OM) {
+  if (OM.lookup(V).first)
+    return;
+
+  if (const Constant *C = dyn_cast<Constant>(V))
+    if (C->getNumOperands() && !isa<GlobalValue>(C))
+      for (const Value *Op : C->operands())
+        if (!isa<BasicBlock>(Op) && !isa<GlobalValue>(Op))
+          orderValue(Op, OM);
+
+  // Note: we cannot cache this lookup above, since inserting into the map
+  // changes the map's size, and thus affects the other IDs.
+  OM.index(V);
+}
+
+static OrderMap orderModule(const Module *M) {
+  // This needs to match the order used by ValueEnumerator::ValueEnumerator()
+  // and ValueEnumerator::incorporateFunction().
+  OrderMap OM;
+
+  for (const GlobalVariable &G : M->globals()) {
+    if (G.hasInitializer())
+      if (!isa<GlobalValue>(G.getInitializer()))
+        orderValue(G.getInitializer(), OM);
+    orderValue(&G, OM);
+  }
+  for (const GlobalAlias &A : M->aliases()) {
+    if (!isa<GlobalValue>(A.getAliasee()))
+      orderValue(A.getAliasee(), OM);
+    orderValue(&A, OM);
+  }
+  for (const Function &F : *M) {
+    if (F.hasPrefixData())
+      if (!isa<GlobalValue>(F.getPrefixData()))
+        orderValue(F.getPrefixData(), OM);
+
+    if (F.hasPrologueData())
+      if (!isa<GlobalValue>(F.getPrologueData()))
+        orderValue(F.getPrologueData(), OM);
+
+    orderValue(&F, OM);
+
+    if (F.isDeclaration())
+      continue;
+
+    for (const Argument &A : F.args())
+      orderValue(&A, OM);
+    for (const BasicBlock &BB : F) {
+      orderValue(&BB, OM);
+      for (const Instruction &I : BB) {
+        for (const Value *Op : I.operands())
+          if ((isa<Constant>(*Op) && !isa<GlobalValue>(*Op)) ||
+              isa<InlineAsm>(*Op))
+            orderValue(Op, OM);
+        orderValue(&I, OM);
+      }
+    }
+  }
+  return OM;
+}
+
+static void predictValueUseListOrderImpl(const Value *V, const Function *F,
+                                         unsigned ID, const OrderMap &OM,
+                                         UseListOrderStack &Stack) {
+  // Predict use-list order for this one.
+  typedef std::pair<const Use *, unsigned> Entry;
+  SmallVector<Entry, 64> List;
+  for (const Use &U : V->uses())
+    // Check if this user will be serialized.
+    if (OM.lookup(U.getUser()).first)
+      List.push_back(std::make_pair(&U, List.size()));
+
+  if (List.size() < 2)
+    // We may have lost some users.
+    return;
+
+  bool GetsReversed =
+      !isa<GlobalVariable>(V) && !isa<Function>(V) && !isa<BasicBlock>(V);
+  if (auto *BA = dyn_cast<BlockAddress>(V))
+    ID = OM.lookup(BA->getBasicBlock()).first;
+  std::sort(List.begin(), List.end(), [&](const Entry &L, const Entry &R) {
+    const Use *LU = L.first;
+    const Use *RU = R.first;
+    if (LU == RU)
+      return false;
+
+    auto LID = OM.lookup(LU->getUser()).first;
+    auto RID = OM.lookup(RU->getUser()).first;
+
+    // If ID is 4, then expect: 7 6 5 1 2 3.
+    if (LID < RID) {
+      if (GetsReversed)
+        if (RID <= ID)
+          return true;
+      return false;
+    }
+    if (RID < LID) {
+      if (GetsReversed)
+        if (LID <= ID)
+          return false;
+      return true;
+    }
+
+    // LID and RID are equal, so we have different operands of the same user.
+    // Assume operands are added in order for all instructions.
+    if (GetsReversed)
+      if (LID <= ID)
+        return LU->getOperandNo() < RU->getOperandNo();
+    return LU->getOperandNo() > RU->getOperandNo();
+  });
+
+  if (std::is_sorted(
+          List.begin(), List.end(),
+          [](const Entry &L, const Entry &R) { return L.second < R.second; }))
+    // Order is already correct.
+    return;
+
+  // Store the shuffle.
+  Stack.emplace_back(V, F, List.size());
+  assert(List.size() == Stack.back().Shuffle.size() && "Wrong size");
+  for (size_t I = 0, E = List.size(); I != E; ++I)
+    Stack.back().Shuffle[I] = List[I].second;
+}
+
+static void predictValueUseListOrder(const Value *V, const Function *F,
+                                     OrderMap &OM, UseListOrderStack &Stack) {
+  auto &IDPair = OM[V];
+  assert(IDPair.first && "Unmapped value");
+  if (IDPair.second)
+    // Already predicted.
+    return;
+
+  // Do the actual prediction.
+  IDPair.second = true;
+  if (!V->use_empty() && std::next(V->use_begin()) != V->use_end())
+    predictValueUseListOrderImpl(V, F, IDPair.first, OM, Stack);
+
+  // Recursive descent into constants.
+  if (const Constant *C = dyn_cast<Constant>(V))
+    if (C->getNumOperands()) // Visit GlobalValues.
+      for (const Value *Op : C->operands())
+        if (isa<Constant>(Op)) // Visit GlobalValues.
+          predictValueUseListOrder(Op, F, OM, Stack);
+}
+
+static UseListOrderStack predictUseListOrder(const Module *M) {
+  OrderMap OM = orderModule(M);
+
+  // Use-list orders need to be serialized after all the users have been added
+  // to a value, or else the shuffles will be incomplete.  Store them per
+  // function in a stack.
+  //
+  // Aside from function order, the order of values doesn't matter much here.
+  UseListOrderStack Stack;
+
+  // We want to visit the functions backward now so we can list function-local
+  // constants in the last Function they're used in.  Module-level constants
+  // have already been visited above.
+  for (auto I = M->rbegin(), E = M->rend(); I != E; ++I) {
+    const Function &F = *I;
+    if (F.isDeclaration())
+      continue;
+    for (const BasicBlock &BB : F)
+      predictValueUseListOrder(&BB, &F, OM, Stack);
+    for (const Argument &A : F.args())
+      predictValueUseListOrder(&A, &F, OM, Stack);
+    for (const BasicBlock &BB : F)
+      for (const Instruction &I : BB)
+        for (const Value *Op : I.operands())
+          if (isa<Constant>(*Op) || isa<InlineAsm>(*Op)) // Visit GlobalValues.
+            predictValueUseListOrder(Op, &F, OM, Stack);
+    for (const BasicBlock &BB : F)
+      for (const Instruction &I : BB)
+        predictValueUseListOrder(&I, &F, OM, Stack);
+  }
+
+  // Visit globals last.
+  for (const GlobalVariable &G : M->globals())
+    predictValueUseListOrder(&G, nullptr, OM, Stack);
+  for (const Function &F : *M)
+    predictValueUseListOrder(&F, nullptr, OM, Stack);
+  for (const GlobalAlias &A : M->aliases())
+    predictValueUseListOrder(&A, nullptr, OM, Stack);
+  for (const GlobalVariable &G : M->globals())
+    if (G.hasInitializer())
+      predictValueUseListOrder(G.getInitializer(), nullptr, OM, Stack);
+  for (const GlobalAlias &A : M->aliases())
+    predictValueUseListOrder(A.getAliasee(), nullptr, OM, Stack);
+  for (const Function &F : *M)
+    if (F.hasPrefixData())
+      predictValueUseListOrder(F.getPrefixData(), nullptr, OM, Stack);
+
+  return Stack;
+}
+
 static const Module *getModuleFromVal(const Value *V) {
   if (const Argument *MA = dyn_cast<Argument>(V))
     return MA->getParent() ? MA->getParent()->getParent() : nullptr;
@@ -63,6 +277,15 @@ static const Module *getModuleFromVal(const Value *V) {
 
   if (const GlobalValue *GV = dyn_cast<GlobalValue>(V))
     return GV->getParent();
+
+  if (const auto *MAV = dyn_cast<MetadataAsValue>(V)) {
+    for (const User *U : MAV->users())
+      if (isa<Instruction>(U))
+        if (const Module *M = getModuleFromVal(U))
+          return M;
+    return nullptr;
+  }
+
   return nullptr;
 }
 
@@ -75,9 +298,11 @@ static void PrintCallingConv(unsigned cc, raw_ostream &Out) {
   case CallingConv::AnyReg:        Out << "anyregcc"; break;
   case CallingConv::PreserveMost:  Out << "preserve_mostcc"; break;
   case CallingConv::PreserveAll:   Out << "preserve_allcc"; break;
+  case CallingConv::GHC:           Out << "ghccc"; break;
   case CallingConv::X86_StdCall:   Out << "x86_stdcallcc"; break;
   case CallingConv::X86_FastCall:  Out << "x86_fastcallcc"; break;
   case CallingConv::X86_ThisCall:  Out << "x86_thiscallcc"; break;
+  case CallingConv::X86_VectorCall:Out << "x86_vectorcallcc"; break;
   case CallingConv::Intel_OCL_BI:  Out << "intel_ocl_bicc"; break;
   case CallingConv::ARM_APCS:      Out << "arm_apcscc"; break;
   case CallingConv::ARM_AAPCS:     Out << "arm_aapcscc"; break;
@@ -106,6 +331,7 @@ static void PrintEscapedString(StringRef Name, raw_ostream &Out) {
 
 enum PrefixType {
   GlobalPrefix,
+  ComdatPrefix,
   LabelPrefix,
   LocalPrefix,
   NoPrefix
@@ -119,6 +345,7 @@ static void PrintLLVMName(raw_ostream &OS, StringRef Name, PrefixType Prefix) {
   switch (Prefix) {
   case NoPrefix: break;
   case GlobalPrefix: OS << '@'; break;
+  case ComdatPrefix: OS << '$'; break;
   case LabelPrefix:  break;
   case LocalPrefix:  OS << '%'; break;
   }
@@ -162,7 +389,29 @@ static void PrintLLVMName(raw_ostream &OS, const Value *V) {
 }
 
 
-namespace llvm {
+namespace {
+class TypePrinting {
+  TypePrinting(const TypePrinting &) = delete;
+  void operator=(const TypePrinting&) = delete;
+public:
+
+  /// NamedTypes - The named types that are used by the current module.
+  TypeFinder NamedTypes;
+
+  /// NumberedTypes - The numbered types, along with their value.
+  DenseMap<StructType*, unsigned> NumberedTypes;
+
+
+  TypePrinting() {}
+  ~TypePrinting() {}
+
+  void incorporateTypes(const Module &M);
+
+  void print(Type *Ty, raw_ostream &OS);
+
+  void printStructBody(StructType *Ty, raw_ostream &OS);
+};
+} // namespace
 
 void TypePrinting::incorporateTypes(const Module &M) {
   NamedTypes.run(M, false);
@@ -292,6 +541,7 @@ void TypePrinting::printStructBody(StructType *STy, raw_ostream &OS) {
     OS << '>';
 }
 
+namespace {
 //===----------------------------------------------------------------------===//
 // SlotTracker Class: Enumerate slot numbers for unnamed values
 //===----------------------------------------------------------------------===//
@@ -309,6 +559,7 @@ private:
   /// TheFunction - The function for which we are holding slot numbers.
   const Function* TheFunction;
   bool FunctionProcessed;
+  bool ShouldInitializeAllMetadata;
 
   /// mMap - The slot map for the module level data.
   ValueMap mMap;
@@ -326,10 +577,20 @@ private:
   DenseMap<AttributeSet, unsigned> asMap;
   unsigned asNext;
 public:
-  /// Construct from a module
-  explicit SlotTracker(const Module *M);
+  /// Construct from a module.
+  ///
+  /// If \c ShouldInitializeAllMetadata, initializes all metadata in all
+  /// functions, giving correct numbering for metadata referenced only from
+  /// within a function (even if no functions have been initialized).
+  explicit SlotTracker(const Module *M,
+                       bool ShouldInitializeAllMetadata = false);
   /// Construct from a function, starting out in incorp state.
-  explicit SlotTracker(const Function *F);
+  ///
+  /// If \c ShouldInitializeAllMetadata, initializes all metadata in all
+  /// functions, giving correct numbering for metadata referenced only from
+  /// within a function (even if no functions have been initialized).
+  explicit SlotTracker(const Function *F,
+                       bool ShouldInitializeAllMetadata = false);
 
   /// Return the slot number of the specified value in it's type
   /// plane.  If something is not in the SlotTracker, return -1.
@@ -345,6 +606,8 @@ public:
     FunctionProcessed = false;
   }
 
+  const Function *getFunction() const { return TheFunction; }
+
   /// After calling incorporateFunction, use this method to remove the
   /// most recently incorporated function from the SlotTracker. This
   /// will reset the state of the machine back to just the module contents.
@@ -388,11 +651,18 @@ private:
   /// Add all of the functions arguments, basic blocks, and instructions.
   void processFunction();
 
-  SlotTracker(const SlotTracker &) LLVM_DELETED_FUNCTION;
-  void operator=(const SlotTracker &) LLVM_DELETED_FUNCTION;
+  /// Add all of the metadata from a function.
+  void processFunctionMetadata(const Function &F);
+
+  /// Add all of the metadata from an instruction.
+  void processInstructionMetadata(const Instruction &I);
+
+  SlotTracker(const SlotTracker &) = delete;
+  void operator=(const SlotTracker &) = delete;
 };
+} // namespace
 
-SlotTracker *createSlotTracker(const Module *M) {
+static SlotTracker *createSlotTracker(const Module *M) {
   return new SlotTracker(M);
 }
 
@@ -416,13 +686,6 @@ static SlotTracker *createSlotTracker(const Value *V) {
   if (const Function *Func = dyn_cast<Function>(V))
     return new SlotTracker(Func);
 
-  if (const MDNode *MD = dyn_cast<MDNode>(V)) {
-    if (!MD->isFunctionLocal())
-      return new SlotTracker(MD->getFunction());
-
-    return new SlotTracker((Function *)nullptr);
-  }
-
   return nullptr;
 }
 
@@ -434,17 +697,18 @@ static SlotTracker *createSlotTracker(const Value *V) {
 
 // Module level constructor. Causes the contents of the Module (sans functions)
 // to be added to the slot table.
-SlotTracker::SlotTracker(const Module *M)
-  : TheModule(M), TheFunction(nullptr), FunctionProcessed(false),
-    mNext(0), fNext(0),  mdnNext(0), asNext(0) {
-}
+SlotTracker::SlotTracker(const Module *M, bool ShouldInitializeAllMetadata)
+    : TheModule(M), TheFunction(nullptr), FunctionProcessed(false),
+      ShouldInitializeAllMetadata(ShouldInitializeAllMetadata), mNext(0),
+      fNext(0), mdnNext(0), asNext(0) {}
 
 // Function level constructor. Causes the contents of the Module and the one
 // function provided to be added to the slot table.
-SlotTracker::SlotTracker(const Function *F)
-  : TheModule(F ? F->getParent() : nullptr), TheFunction(F),
-    FunctionProcessed(false), mNext(0), fNext(0), mdnNext(0), asNext(0) {
-}
+SlotTracker::SlotTracker(const Function *F, bool ShouldInitializeAllMetadata)
+    : TheModule(F ? F->getParent() : nullptr), TheFunction(F),
+      FunctionProcessed(false),
+      ShouldInitializeAllMetadata(ShouldInitializeAllMetadata), mNext(0),
+      fNext(0), mdnNext(0), asNext(0) {}
 
 inline void SlotTracker::initialize() {
   if (TheModule) {
@@ -483,6 +747,9 @@ void SlotTracker::processModule() {
       // Add all the unnamed functions to the table.
       CreateModuleSlot(I);
 
+    if (ShouldInitializeAllMetadata)
+      processFunctionMetadata(*I);
+
     // Add all the function attributes to the table.
     // FIXME: Add attributes of other objects?
     AttributeSet FnAttrs = I->getAttributes().getFnAttributes();
@@ -506,45 +773,30 @@ void SlotTracker::processFunction() {
 
   ST_DEBUG("Inserting Instructions:\n");
 
-  SmallVector<std::pair<unsigned, MDNode*>, 4> MDForInst;
-
   // Add all of the basic blocks and instructions with no names.
-  for (Function::const_iterator BB = TheFunction->begin(),
-       E = TheFunction->end(); BB != E; ++BB) {
-    if (!BB->hasName())
-      CreateFunctionSlot(BB);
-
-    for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E;
-         ++I) {
-      if (!I->getType()->isVoidTy() && !I->hasName())
-        CreateFunctionSlot(I);
-
-      // Intrinsics can directly use metadata.  We allow direct calls to any
-      // llvm.foo function here, because the target may not be linked into the
-      // optimizer.
-      if (const CallInst *CI = dyn_cast<CallInst>(I)) {
-        if (Function *F = CI->getCalledFunction())
-          if (F->isIntrinsic())
-            for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
-              if (MDNode *N = dyn_cast_or_null<MDNode>(I->getOperand(i)))
-                CreateMetadataSlot(N);
+  for (auto &BB : *TheFunction) {
+    if (!BB.hasName())
+      CreateFunctionSlot(&BB);
+
+    for (auto &I : BB) {
+      if (!I.getType()->isVoidTy() && !I.hasName())
+        CreateFunctionSlot(&I);
 
+      processInstructionMetadata(I);
+
+      // We allow direct calls to any llvm.foo function here, because the
+      // target may not be linked into the optimizer.
+      if (const CallInst *CI = dyn_cast<CallInst>(&I)) {
         // Add all the call attributes to the table.
         AttributeSet Attrs = CI->getAttributes().getFnAttributes();
         if (Attrs.hasAttributes(AttributeSet::FunctionIndex))
           CreateAttributeSetSlot(Attrs);
-      } else if (const InvokeInst *II = dyn_cast<InvokeInst>(I)) {
+      } else if (const InvokeInst *II = dyn_cast<InvokeInst>(&I)) {
         // Add all the call attributes to the table.
         AttributeSet Attrs = II->getAttributes().getFnAttributes();
         if (Attrs.hasAttributes(AttributeSet::FunctionIndex))
           CreateAttributeSetSlot(Attrs);
       }
-
-      // Process metadata attached with this instruction.
-      I->getAllMetadata(MDForInst);
-      for (unsigned i = 0, e = MDForInst.size(); i != e; ++i)
-        CreateMetadataSlot(MDForInst[i].second);
-      MDForInst.clear();
     }
   }
 
@@ -553,6 +805,29 @@ void SlotTracker::processFunction() {
   ST_DEBUG("end processFunction!\n");
 }
 
+void SlotTracker::processFunctionMetadata(const Function &F) {
+  for (auto &BB : F)
+    for (auto &I : BB)
+      processInstructionMetadata(I);
+}
+
+void SlotTracker::processInstructionMetadata(const Instruction &I) {
+  // Process metadata used directly by intrinsics.
+  if (const CallInst *CI = dyn_cast<CallInst>(&I))
+    if (Function *F = CI->getCalledFunction())
+      if (F->isIntrinsic())
+        for (auto &Op : I.operands())
+          if (auto *V = dyn_cast_or_null<MetadataAsValue>(Op))
+            if (MDNode *N = dyn_cast<MDNode>(V->getMetadata()))
+              CreateMetadataSlot(N);
+
+  // Process metadata attached to this instruction.
+  SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
+  I.getAllMetadata(MDs);
+  for (auto &MD : MDs)
+    CreateMetadataSlot(MD.second);
+}
+
 /// Clean up after incorporating a function. This is the only way to get out of
 /// the function incorporation state that affects get*Slot/Create*Slot. Function
 /// incorporation state is indicated by TheFunction != 0.
@@ -638,16 +913,10 @@ void SlotTracker::CreateFunctionSlot(const Value *V) {
 void SlotTracker::CreateMetadataSlot(const MDNode *N) {
   assert(N && "Can't insert a null Value into SlotTracker!");
 
-  // Don't insert if N is a function-local metadata, these are always printed
-  // inline.
-  if (!N->isFunctionLocal()) {
-    mdn_iterator I = mdnMap.find(N);
-    if (I != mdnMap.end())
-      return;
-
-    unsigned DestSlot = mdnNext++;
-    mdnMap[N] = DestSlot;
-  }
+  unsigned DestSlot = mdnNext;
+  if (!mdnMap.insert(std::make_pair(N, DestSlot)).second)
+    return;
+  ++mdnNext;
 
   // Recursively add any MDNodes referenced by operands.
   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
@@ -676,6 +945,11 @@ static void WriteAsOperandInternal(raw_ostream &Out, const Value *V,
                                    SlotTracker *Machine,
                                    const Module *Context);
 
+static void WriteAsOperandInternal(raw_ostream &Out, const Metadata *MD,
+                                   TypePrinting *TypePrinter,
+                                   SlotTracker *Machine, const Module *Context,
+                                   bool FromValue = false);
+
 static const char *getPredicateText(unsigned predicate) {
   const char * pred = "unknown";
   switch (predicate) {
@@ -801,7 +1075,7 @@ static void WriteConstantInternal(raw_ostream &Out, const Constant *CV,
              (StrVal[1] >= '0' && StrVal[1] <= '9'))) {
           // Reparse stringized version!
           if (APFloat(APFloat::IEEEdouble, StrVal).convertToDouble() == Val) {
-            Out << StrVal.str();
+            Out << StrVal;
             return;
           }
         }
@@ -1014,6 +1288,14 @@ static void WriteConstantInternal(raw_ostream &Out, const Constant *CV,
       Out << ' ' << getPredicateText(CE->getPredicate());
     Out << " (";
 
+    if (const GEPOperator *GEP = dyn_cast<GEPOperator>(CE)) {
+      TypePrinter.print(
+          cast<PointerType>(GEP->getPointerOperandType()->getScalarType())
+              ->getElementType(),
+          Out);
+      Out << ", ";
+    }
+
     for (User::const_op_iterator OI=CE->op_begin(); OI != CE->op_end(); ++OI) {
       TypePrinter.print((*OI)->getType(), Out);
       Out << ' ';
@@ -1040,20 +1322,21 @@ static void WriteConstantInternal(raw_ostream &Out, const Constant *CV,
   Out << "<placeholder or erroneous Constant>";
 }
 
-static void WriteMDNodeBodyInternal(raw_ostream &Out, const MDNode *Node,
-                                    TypePrinting *TypePrinter,
-                                    SlotTracker *Machine,
-                                    const Module *Context) {
+static void writeMDTuple(raw_ostream &Out, const MDTuple *Node,
+                         TypePrinting *TypePrinter, SlotTracker *Machine,
+                         const Module *Context) {
   Out << "!{";
   for (unsigned mi = 0, me = Node->getNumOperands(); mi != me; ++mi) {
-    const Value *V = Node->getOperand(mi);
-    if (!V)
+    const Metadata *MD = Node->getOperand(mi);
+    if (!MD)
       Out << "null";
-    else {
+    else if (auto *MDV = dyn_cast<ValueAsMetadata>(MD)) {
+      Value *V = MDV->getValue();
       TypePrinter->print(V->getType(), Out);
       Out << ' ';
-      WriteAsOperandInternal(Out, Node->getOperand(mi),
-                             TypePrinter, Machine, Context);
+      WriteAsOperandInternal(Out, V, TypePrinter, Machine, Context);
+    } else {
+      WriteAsOperandInternal(Out, MD, TypePrinter, Machine, Context);
     }
     if (mi + 1 != me)
       Out << ", ";
@@ -1062,6 +1345,481 @@ static void WriteMDNodeBodyInternal(raw_ostream &Out, const MDNode *Node,
   Out << "}";
 }
 
+namespace {
+struct FieldSeparator {
+  bool Skip;
+  const char *Sep;
+  FieldSeparator(const char *Sep = ", ") : Skip(true), Sep(Sep) {}
+};
+raw_ostream &operator<<(raw_ostream &OS, FieldSeparator &FS) {
+  if (FS.Skip) {
+    FS.Skip = false;
+    return OS;
+  }
+  return OS << FS.Sep;
+}
+struct MDFieldPrinter {
+  raw_ostream &Out;
+  FieldSeparator FS;
+  TypePrinting *TypePrinter;
+  SlotTracker *Machine;
+  const Module *Context;
+
+  explicit MDFieldPrinter(raw_ostream &Out)
+      : Out(Out), TypePrinter(nullptr), Machine(nullptr), Context(nullptr) {}
+  MDFieldPrinter(raw_ostream &Out, TypePrinting *TypePrinter,
+                 SlotTracker *Machine, const Module *Context)
+      : Out(Out), TypePrinter(TypePrinter), Machine(Machine), Context(Context) {
+  }
+  void printTag(const DebugNode *N);
+  void printString(StringRef Name, StringRef Value,
+                   bool ShouldSkipEmpty = true);
+  void printMetadata(StringRef Name, const Metadata *MD,
+                     bool ShouldSkipNull = true);
+  template <class IntTy>
+  void printInt(StringRef Name, IntTy Int, bool ShouldSkipZero = true);
+  void printBool(StringRef Name, bool Value);
+  void printDIFlags(StringRef Name, unsigned Flags);
+  template <class IntTy, class Stringifier>
+  void printDwarfEnum(StringRef Name, IntTy Value, Stringifier toString,
+                      bool ShouldSkipZero = true);
+};
+} // end namespace
+
+void MDFieldPrinter::printTag(const DebugNode *N) {
+  Out << FS << "tag: ";
+  if (const char *Tag = dwarf::TagString(N->getTag()))
+    Out << Tag;
+  else
+    Out << N->getTag();
+}
+
+void MDFieldPrinter::printString(StringRef Name, StringRef Value,
+                                 bool ShouldSkipEmpty) {
+  if (ShouldSkipEmpty && Value.empty())
+    return;
+
+  Out << FS << Name << ": \"";
+  PrintEscapedString(Value, Out);
+  Out << "\"";
+}
+
+static void writeMetadataAsOperand(raw_ostream &Out, const Metadata *MD,
+                                   TypePrinting *TypePrinter,
+                                   SlotTracker *Machine,
+                                   const Module *Context) {
+  if (!MD) {
+    Out << "null";
+    return;
+  }
+  WriteAsOperandInternal(Out, MD, TypePrinter, Machine, Context);
+}
+
+void MDFieldPrinter::printMetadata(StringRef Name, const Metadata *MD,
+                                   bool ShouldSkipNull) {
+  if (ShouldSkipNull && !MD)
+    return;
+
+  Out << FS << Name << ": ";
+  writeMetadataAsOperand(Out, MD, TypePrinter, Machine, Context);
+}
+
+template <class IntTy>
+void MDFieldPrinter::printInt(StringRef Name, IntTy Int, bool ShouldSkipZero) {
+  if (ShouldSkipZero && !Int)
+    return;
+
+  Out << FS << Name << ": " << Int;
+}
+
+void MDFieldPrinter::printBool(StringRef Name, bool Value) {
+  Out << FS << Name << ": " << (Value ? "true" : "false");
+}
+
+void MDFieldPrinter::printDIFlags(StringRef Name, unsigned Flags) {
+  if (!Flags)
+    return;
+
+  Out << FS << Name << ": ";
+
+  SmallVector<unsigned, 8> SplitFlags;
+  unsigned Extra = DIDescriptor::splitFlags(Flags, SplitFlags);
+
+  FieldSeparator FlagsFS(" | ");
+  for (unsigned F : SplitFlags) {
+    const char *StringF = DIDescriptor::getFlagString(F);
+    assert(StringF && "Expected valid flag");
+    Out << FlagsFS << StringF;
+  }
+  if (Extra || SplitFlags.empty())
+    Out << FlagsFS << Extra;
+}
+
+template <class IntTy, class Stringifier>
+void MDFieldPrinter::printDwarfEnum(StringRef Name, IntTy Value,
+                                    Stringifier toString, bool ShouldSkipZero) {
+  if (!Value)
+    return;
+
+  Out << FS << Name << ": ";
+  if (const char *S = toString(Value))
+    Out << S;
+  else
+    Out << Value;
+}
+
+static void writeGenericDebugNode(raw_ostream &Out, const GenericDebugNode *N,
+                                  TypePrinting *TypePrinter,
+                                  SlotTracker *Machine, const Module *Context) {
+  Out << "!GenericDebugNode(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printTag(N);
+  Printer.printString("header", N->getHeader());
+  if (N->getNumDwarfOperands()) {
+    Out << Printer.FS << "operands: {";
+    FieldSeparator IFS;
+    for (auto &I : N->dwarf_operands()) {
+      Out << IFS;
+      writeMetadataAsOperand(Out, I, TypePrinter, Machine, Context);
+    }
+    Out << "}";
+  }
+  Out << ")";
+}
+
+static void writeMDLocation(raw_ostream &Out, const MDLocation *DL,
+                            TypePrinting *TypePrinter, SlotTracker *Machine,
+                            const Module *Context) {
+  Out << "!MDLocation(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  // Always output the line, since 0 is a relevant and important value for it.
+  Printer.printInt("line", DL->getLine(), /* ShouldSkipZero */ false);
+  Printer.printInt("column", DL->getColumn());
+  Printer.printMetadata("scope", DL->getRawScope(), /* ShouldSkipNull */ false);
+  Printer.printMetadata("inlinedAt", DL->getRawInlinedAt());
+  Out << ")";
+}
+
+static void writeMDSubrange(raw_ostream &Out, const MDSubrange *N,
+                            TypePrinting *, SlotTracker *, const Module *) {
+  Out << "!MDSubrange(";
+  MDFieldPrinter Printer(Out);
+  Printer.printInt("count", N->getCount(), /* ShouldSkipZero */ false);
+  Printer.printInt("lowerBound", N->getLo());
+  Out << ")";
+}
+
+static void writeMDEnumerator(raw_ostream &Out, const MDEnumerator *N,
+                              TypePrinting *, SlotTracker *, const Module *) {
+  Out << "!MDEnumerator(";
+  MDFieldPrinter Printer(Out);
+  Printer.printString("name", N->getName(), /* ShouldSkipEmpty */ false);
+  Printer.printInt("value", N->getValue(), /* ShouldSkipZero */ false);
+  Out << ")";
+}
+
+static void writeMDBasicType(raw_ostream &Out, const MDBasicType *N,
+                             TypePrinting *, SlotTracker *, const Module *) {
+  Out << "!MDBasicType(";
+  MDFieldPrinter Printer(Out);
+  if (N->getTag() != dwarf::DW_TAG_base_type)
+    Printer.printTag(N);
+  Printer.printString("name", N->getName());
+  Printer.printInt("size", N->getSizeInBits());
+  Printer.printInt("align", N->getAlignInBits());
+  Printer.printDwarfEnum("encoding", N->getEncoding(),
+                         dwarf::AttributeEncodingString);
+  Out << ")";
+}
+
+static void writeMDDerivedType(raw_ostream &Out, const MDDerivedType *N,
+                               TypePrinting *TypePrinter, SlotTracker *Machine,
+                               const Module *Context) {
+  Out << "!MDDerivedType(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printTag(N);
+  Printer.printString("name", N->getName());
+  Printer.printMetadata("scope", N->getScope());
+  Printer.printMetadata("file", N->getFile());
+  Printer.printInt("line", N->getLine());
+  Printer.printMetadata("baseType", N->getBaseType(),
+                        /* ShouldSkipNull */ false);
+  Printer.printInt("size", N->getSizeInBits());
+  Printer.printInt("align", N->getAlignInBits());
+  Printer.printInt("offset", N->getOffsetInBits());
+  Printer.printDIFlags("flags", N->getFlags());
+  Printer.printMetadata("extraData", N->getExtraData());
+  Out << ")";
+}
+
+static void writeMDCompositeType(raw_ostream &Out, const MDCompositeType *N,
+                                 TypePrinting *TypePrinter,
+                                 SlotTracker *Machine, const Module *Context) {
+  Out << "!MDCompositeType(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printTag(N);
+  Printer.printString("name", N->getName());
+  Printer.printMetadata("scope", N->getScope());
+  Printer.printMetadata("file", N->getFile());
+  Printer.printInt("line", N->getLine());
+  Printer.printMetadata("baseType", N->getBaseType());
+  Printer.printInt("size", N->getSizeInBits());
+  Printer.printInt("align", N->getAlignInBits());
+  Printer.printInt("offset", N->getOffsetInBits());
+  Printer.printDIFlags("flags", N->getFlags());
+  Printer.printMetadata("elements", N->getElements());
+  Printer.printDwarfEnum("runtimeLang", N->getRuntimeLang(),
+                         dwarf::LanguageString);
+  Printer.printMetadata("vtableHolder", N->getVTableHolder());
+  Printer.printMetadata("templateParams", N->getTemplateParams());
+  Printer.printString("identifier", N->getIdentifier());
+  Out << ")";
+}
+
+static void writeMDSubroutineType(raw_ostream &Out, const MDSubroutineType *N,
+                                  TypePrinting *TypePrinter,
+                                  SlotTracker *Machine, const Module *Context) {
+  Out << "!MDSubroutineType(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printDIFlags("flags", N->getFlags());
+  Printer.printMetadata("types", N->getTypeArray(), /* ShouldSkipNull */ false);
+  Out << ")";
+}
+
+static void writeMDFile(raw_ostream &Out, const MDFile *N, TypePrinting *,
+                        SlotTracker *, const Module *) {
+  Out << "!MDFile(";
+  MDFieldPrinter Printer(Out);
+  Printer.printString("filename", N->getFilename(),
+                      /* ShouldSkipEmpty */ false);
+  Printer.printString("directory", N->getDirectory(),
+                      /* ShouldSkipEmpty */ false);
+  Out << ")";
+}
+
+static void writeMDCompileUnit(raw_ostream &Out, const MDCompileUnit *N,
+                               TypePrinting *TypePrinter, SlotTracker *Machine,
+                               const Module *Context) {
+  Out << "!MDCompileUnit(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printDwarfEnum("language", N->getSourceLanguage(),
+                         dwarf::LanguageString, /* ShouldSkipZero */ false);
+  Printer.printMetadata("file", N->getFile(), /* ShouldSkipNull */ false);
+  Printer.printString("producer", N->getProducer());
+  Printer.printBool("isOptimized", N->isOptimized());
+  Printer.printString("flags", N->getFlags());
+  Printer.printInt("runtimeVersion", N->getRuntimeVersion(),
+                   /* ShouldSkipZero */ false);
+  Printer.printString("splitDebugFilename", N->getSplitDebugFilename());
+  Printer.printInt("emissionKind", N->getEmissionKind(),
+                   /* ShouldSkipZero */ false);
+  Printer.printMetadata("enums", N->getEnumTypes());
+  Printer.printMetadata("retainedTypes", N->getRetainedTypes());
+  Printer.printMetadata("subprograms", N->getSubprograms());
+  Printer.printMetadata("globals", N->getGlobalVariables());
+  Printer.printMetadata("imports", N->getImportedEntities());
+  Out << ")";
+}
+
+static void writeMDSubprogram(raw_ostream &Out, const MDSubprogram *N,
+                              TypePrinting *TypePrinter, SlotTracker *Machine,
+                              const Module *Context) {
+  Out << "!MDSubprogram(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printString("name", N->getName());
+  Printer.printString("linkageName", N->getLinkageName());
+  Printer.printMetadata("scope", N->getScope(), /* ShouldSkipNull */ false);
+  Printer.printMetadata("file", N->getFile());
+  Printer.printInt("line", N->getLine());
+  Printer.printMetadata("type", N->getType());
+  Printer.printBool("isLocal", N->isLocalToUnit());
+  Printer.printBool("isDefinition", N->isDefinition());
+  Printer.printInt("scopeLine", N->getScopeLine());
+  Printer.printMetadata("containingType", N->getContainingType());
+  Printer.printDwarfEnum("virtuality", N->getVirtuality(),
+                         dwarf::VirtualityString);
+  Printer.printInt("virtualIndex", N->getVirtualIndex());
+  Printer.printDIFlags("flags", N->getFlags());
+  Printer.printBool("isOptimized", N->isOptimized());
+  Printer.printMetadata("function", N->getFunction());
+  Printer.printMetadata("templateParams", N->getTemplateParams());
+  Printer.printMetadata("declaration", N->getDeclaration());
+  Printer.printMetadata("variables", N->getVariables());
+  Out << ")";
+}
+
+static void writeMDLexicalBlock(raw_ostream &Out, const MDLexicalBlock *N,
+                              TypePrinting *TypePrinter, SlotTracker *Machine,
+                              const Module *Context) {
+  Out << "!MDLexicalBlock(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printMetadata("scope", N->getScope(), /* ShouldSkipNull */ false);
+  Printer.printMetadata("file", N->getFile());
+  Printer.printInt("line", N->getLine());
+  Printer.printInt("column", N->getColumn());
+  Out << ")";
+}
+
+static void writeMDLexicalBlockFile(raw_ostream &Out,
+                                    const MDLexicalBlockFile *N,
+                                    TypePrinting *TypePrinter,
+                                    SlotTracker *Machine,
+                                    const Module *Context) {
+  Out << "!MDLexicalBlockFile(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printMetadata("scope", N->getScope(), /* ShouldSkipNull */ false);
+  Printer.printMetadata("file", N->getFile());
+  Printer.printInt("discriminator", N->getDiscriminator(),
+                   /* ShouldSkipZero */ false);
+  Out << ")";
+}
+
+static void writeMDNamespace(raw_ostream &Out, const MDNamespace *N,
+                             TypePrinting *TypePrinter, SlotTracker *Machine,
+                             const Module *Context) {
+  Out << "!MDNamespace(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printString("name", N->getName());
+  Printer.printMetadata("scope", N->getScope(), /* ShouldSkipNull */ false);
+  Printer.printMetadata("file", N->getFile());
+  Printer.printInt("line", N->getLine());
+  Out << ")";
+}
+
+static void writeMDTemplateTypeParameter(raw_ostream &Out,
+                                         const MDTemplateTypeParameter *N,
+                                         TypePrinting *TypePrinter,
+                                         SlotTracker *Machine,
+                                         const Module *Context) {
+  Out << "!MDTemplateTypeParameter(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printString("name", N->getName());
+  Printer.printMetadata("type", N->getType(), /* ShouldSkipNull */ false);
+  Out << ")";
+}
+
+static void writeMDTemplateValueParameter(raw_ostream &Out,
+                                          const MDTemplateValueParameter *N,
+                                          TypePrinting *TypePrinter,
+                                          SlotTracker *Machine,
+                                          const Module *Context) {
+  Out << "!MDTemplateValueParameter(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  if (N->getTag() != dwarf::DW_TAG_template_value_parameter)
+    Printer.printTag(N);
+  Printer.printString("name", N->getName());
+  Printer.printMetadata("type", N->getType());
+  Printer.printMetadata("value", N->getValue(), /* ShouldSkipNull */ false);
+  Out << ")";
+}
+
+static void writeMDGlobalVariable(raw_ostream &Out, const MDGlobalVariable *N,
+                                  TypePrinting *TypePrinter,
+                                  SlotTracker *Machine, const Module *Context) {
+  Out << "!MDGlobalVariable(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printString("name", N->getName());
+  Printer.printString("linkageName", N->getLinkageName());
+  Printer.printMetadata("scope", N->getScope(), /* ShouldSkipNull */ false);
+  Printer.printMetadata("file", N->getFile());
+  Printer.printInt("line", N->getLine());
+  Printer.printMetadata("type", N->getType());
+  Printer.printBool("isLocal", N->isLocalToUnit());
+  Printer.printBool("isDefinition", N->isDefinition());
+  Printer.printMetadata("variable", N->getVariable());
+  Printer.printMetadata("declaration", N->getStaticDataMemberDeclaration());
+  Out << ")";
+}
+
+static void writeMDLocalVariable(raw_ostream &Out, const MDLocalVariable *N,
+                                 TypePrinting *TypePrinter,
+                                 SlotTracker *Machine, const Module *Context) {
+  Out << "!MDLocalVariable(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printTag(N);
+  Printer.printString("name", N->getName());
+  Printer.printInt("arg", N->getArg(),
+                   /* ShouldSkipZero */
+                   N->getTag() == dwarf::DW_TAG_auto_variable);
+  Printer.printMetadata("scope", N->getScope(), /* ShouldSkipNull */ false);
+  Printer.printMetadata("file", N->getFile());
+  Printer.printInt("line", N->getLine());
+  Printer.printMetadata("type", N->getType());
+  Printer.printDIFlags("flags", N->getFlags());
+  Printer.printMetadata("inlinedAt", N->getInlinedAt());
+  Out << ")";
+}
+
+static void writeMDExpression(raw_ostream &Out, const MDExpression *N,
+                              TypePrinting *TypePrinter, SlotTracker *Machine,
+                              const Module *Context) {
+  Out << "!MDExpression(";
+  FieldSeparator FS;
+  if (N->isValid()) {
+    for (auto I = N->expr_op_begin(), E = N->expr_op_end(); I != E; ++I) {
+      const char *OpStr = dwarf::OperationEncodingString(I->getOp());
+      assert(OpStr && "Expected valid opcode");
+
+      Out << FS << OpStr;
+      for (unsigned A = 0, AE = I->getNumArgs(); A != AE; ++A)
+        Out << FS << I->getArg(A);
+    }
+  } else {
+    for (const auto &I : N->getElements())
+      Out << FS << I;
+  }
+  Out << ")";
+}
+
+static void writeMDObjCProperty(raw_ostream &Out, const MDObjCProperty *N,
+                                TypePrinting *TypePrinter, SlotTracker *Machine,
+                                const Module *Context) {
+  Out << "!MDObjCProperty(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printString("name", N->getName());
+  Printer.printMetadata("file", N->getFile());
+  Printer.printInt("line", N->getLine());
+  Printer.printString("setter", N->getSetterName());
+  Printer.printString("getter", N->getGetterName());
+  Printer.printInt("attributes", N->getAttributes());
+  Printer.printMetadata("type", N->getType());
+  Out << ")";
+}
+
+static void writeMDImportedEntity(raw_ostream &Out, const MDImportedEntity *N,
+                                  TypePrinting *TypePrinter,
+                                  SlotTracker *Machine, const Module *Context) {
+  Out << "!MDImportedEntity(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+  Printer.printTag(N);
+  Printer.printString("name", N->getName());
+  Printer.printMetadata("scope", N->getScope(), /* ShouldSkipNull */ false);
+  Printer.printMetadata("entity", N->getEntity());
+  Printer.printInt("line", N->getLine());
+  Out << ")";
+}
+
+
+static void WriteMDNodeBodyInternal(raw_ostream &Out, const MDNode *Node,
+                                    TypePrinting *TypePrinter,
+                                    SlotTracker *Machine,
+                                    const Module *Context) {
+  if (Node->isDistinct())
+    Out << "distinct ";
+  else if (Node->isTemporary())
+    Out << "<temporary!> "; // Handle broken code.
+
+  switch (Node->getMetadataID()) {
+  default:
+    llvm_unreachable("Expected uniquable MDNode");
+#define HANDLE_MDNODE_LEAF(CLASS)                                              \
+  case Metadata::CLASS##Kind:                                                  \
+    write##CLASS(Out, cast<CLASS>(Node), TypePrinter, Machine, Context);       \
+    break;
+#include "llvm/IR/Metadata.def"
+  }
+}
+
 // Full implementation of printing a Value as an operand with support for
 // TypePrinting, etc.
 static void WriteAsOperandInternal(raw_ostream &Out, const Value *V,
@@ -1097,31 +1855,9 @@ static void WriteAsOperandInternal(raw_ostream &Out, const Value *V,
     return;
   }
 
-  if (const MDNode *N = dyn_cast<MDNode>(V)) {
-    if (N->isFunctionLocal()) {
-      // Print metadata inline, not via slot reference number.
-      WriteMDNodeBodyInternal(Out, N, TypePrinter, Machine, Context);
-      return;
-    }
-
-    if (!Machine) {
-      if (N->isFunctionLocal())
-        Machine = new SlotTracker(N->getFunction());
-      else
-        Machine = new SlotTracker(Context);
-    }
-    int Slot = Machine->getMetadataSlot(N);
-    if (Slot == -1)
-      Out << "<badref>";
-    else
-      Out << '!' << Slot;
-    return;
-  }
-
-  if (const MDString *MDS = dyn_cast<MDString>(V)) {
-    Out << "!\"";
-    PrintEscapedString(MDS->getString(), Out);
-    Out << '"';
+  if (auto *MD = dyn_cast<MetadataAsValue>(V)) {
+    WriteAsOperandInternal(Out, MD->getMetadata(), TypePrinter, Machine,
+                           Context, /* FromValue */ true);
     return;
   }
 
@@ -1164,9 +1900,108 @@ static void WriteAsOperandInternal(raw_ostream &Out, const Value *V,
     Out << "<badref>";
 }
 
+static void WriteAsOperandInternal(raw_ostream &Out, const Metadata *MD,
+                                   TypePrinting *TypePrinter,
+                                   SlotTracker *Machine, const Module *Context,
+                                   bool FromValue) {
+  if (const MDNode *N = dyn_cast<MDNode>(MD)) {
+    if (!Machine)
+      Machine = new SlotTracker(Context);
+    int Slot = Machine->getMetadataSlot(N);
+    if (Slot == -1)
+      // Give the pointer value instead of "badref", since this comes up all
+      // the time when debugging.
+      Out << "<" << N << ">";
+    else
+      Out << '!' << Slot;
+    return;
+  }
+
+  if (const MDString *MDS = dyn_cast<MDString>(MD)) {
+    Out << "!\"";
+    PrintEscapedString(MDS->getString(), Out);
+    Out << '"';
+    return;
+  }
+
+  auto *V = cast<ValueAsMetadata>(MD);
+  assert(TypePrinter && "TypePrinter required for metadata values");
+  assert((FromValue || !isa<LocalAsMetadata>(V)) &&
+         "Unexpected function-local metadata outside of value argument");
+
+  TypePrinter->print(V->getValue()->getType(), Out);
+  Out << ' ';
+  WriteAsOperandInternal(Out, V->getValue(), TypePrinter, Machine, Context);
+}
+
+namespace {
+class AssemblyWriter {
+  formatted_raw_ostream &Out;
+  const Module *TheModule;
+  std::unique_ptr<SlotTracker> ModuleSlotTracker;
+  SlotTracker &Machine;
+  TypePrinting TypePrinter;
+  AssemblyAnnotationWriter *AnnotationWriter;
+  SetVector<const Comdat *> Comdats;
+  UseListOrderStack UseListOrders;
+
+public:
+  /// Construct an AssemblyWriter with an external SlotTracker
+  AssemblyWriter(formatted_raw_ostream &o, SlotTracker &Mac,
+                 const Module *M, AssemblyAnnotationWriter *AAW);
+
+  /// Construct an AssemblyWriter with an internally allocated SlotTracker
+  AssemblyWriter(formatted_raw_ostream &o, const Module *M,
+                 AssemblyAnnotationWriter *AAW);
+
+  void printMDNodeBody(const MDNode *MD);
+  void printNamedMDNode(const NamedMDNode *NMD);
+
+  void printModule(const Module *M);
+
+  void writeOperand(const Value *Op, bool PrintType);
+  void writeParamOperand(const Value *Operand, AttributeSet Attrs,unsigned Idx);
+  void writeAtomic(AtomicOrdering Ordering, SynchronizationScope SynchScope);
+  void writeAtomicCmpXchg(AtomicOrdering SuccessOrdering,
+                          AtomicOrdering FailureOrdering,
+                          SynchronizationScope SynchScope);
+
+  void writeAllMDNodes();
+  void writeMDNode(unsigned Slot, const MDNode *Node);
+  void writeAllAttributeGroups();
+
+  void printTypeIdentities();
+  void printGlobal(const GlobalVariable *GV);
+  void printAlias(const GlobalAlias *GV);
+  void printComdat(const Comdat *C);
+  void printFunction(const Function *F);
+  void printArgument(const Argument *FA, AttributeSet Attrs, unsigned Idx);
+  void printBasicBlock(const BasicBlock *BB);
+  void printInstructionLine(const Instruction &I);
+  void printInstruction(const Instruction &I);
+
+  void printUseListOrder(const UseListOrder &Order);
+  void printUseLists(const Function *F);
+
+private:
+  void init();
+
+  // printInfoComment - Print a little comment after the instruction indicating
+  // which slot it occupies.
+  void printInfoComment(const Value &V);
+};
+} // namespace
+
 void AssemblyWriter::init() {
-  if (TheModule)
-    TypePrinter.incorporateTypes(*TheModule);
+  if (!TheModule)
+    return;
+  TypePrinter.incorporateTypes(*TheModule);
+  for (const Function &F : *TheModule)
+    if (const Comdat *C = F.getComdat())
+      Comdats.insert(C);
+  for (const GlobalVariable &GV : TheModule->globals())
+    if (const Comdat *C = GV.getComdat())
+      Comdats.insert(C);
 }
 
 
@@ -1184,8 +2019,6 @@ AssemblyWriter::AssemblyWriter(formatted_raw_ostream &o, const Module *M,
   init();
 }
 
-AssemblyWriter::~AssemblyWriter() { }
-
 void AssemblyWriter::writeOperand(const Value *Operand, bool PrintType) {
   if (!Operand) {
     Out << "<null operand!>";
@@ -1270,6 +2103,9 @@ void AssemblyWriter::writeParamOperand(const Value *Operand,
 void AssemblyWriter::printModule(const Module *M) {
   Machine.initialize();
 
+  if (shouldPreserveAssemblyUseListOrder())
+    UseListOrders = predictUseListOrder(M);
+
   if (!M->getModuleIdentifier().empty() &&
       // Don't print the ID if it will start a new line (which would
       // require a comment char before it).
@@ -1308,6 +2144,15 @@ void AssemblyWriter::printModule(const Module *M) {
 
   printTypeIdentities();
 
+  // Output all comdats.
+  if (!Comdats.empty())
+    Out << '\n';
+  for (const Comdat *C : Comdats) {
+    printComdat(C);
+    if (C != Comdats.back())
+      Out << '\n';
+  }
+
   // Output all globals.
   if (!M->global_empty()) Out << '\n';
   for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
@@ -1321,9 +2166,13 @@ void AssemblyWriter::printModule(const Module *M) {
        I != E; ++I)
     printAlias(I);
 
+  // Output global use-lists.
+  printUseLists(nullptr);
+
   // Output all of the functions.
   for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I)
     printFunction(I);
+  assert(UseListOrders.empty() && "All use-lists should have been consumed");
 
   // Output all attribute groups.
   if (!Machine.as_empty()) {
@@ -1437,6 +2286,24 @@ static void PrintThreadLocalModel(GlobalVariable::ThreadLocalMode TLM,
   }
 }
 
+static void maybePrintComdat(formatted_raw_ostream &Out,
+                             const GlobalObject &GO) {
+  const Comdat *C = GO.getComdat();
+  if (!C)
+    return;
+
+  if (isa<GlobalVariable>(GO))
+    Out << ',';
+  Out << " comdat";
+
+  if (GO.getName() == C->getName())
+    return;
+
+  Out << '(';
+  PrintLLVMName(Out, C->getName(), ComdatPrefix);
+  Out << ')';
+}
+
 void AssemblyWriter::printGlobal(const GlobalVariable *GV) {
   if (GV->isMaterializable())
     Out << "; Materializable\n";
@@ -1451,10 +2318,11 @@ void AssemblyWriter::printGlobal(const GlobalVariable *GV) {
   PrintVisibility(GV->getVisibility(), Out);
   PrintDLLStorageClass(GV->getDLLStorageClass(), Out);
   PrintThreadLocalModel(GV->getThreadLocalMode(), Out);
+  if (GV->hasUnnamedAddr())
+    Out << "unnamed_addr ";
 
   if (unsigned AddressSpace = GV->getType()->getAddressSpace())
     Out << "addrspace(" << AddressSpace << ") ";
-  if (GV->hasUnnamedAddr()) Out << "unnamed_addr ";
   if (GV->isExternallyInitialized()) Out << "externally_initialized ";
   Out << (GV->isConstant() ? "constant " : "global ");
   TypePrinter.print(GV->getType()->getElementType(), Out);
@@ -1469,6 +2337,7 @@ void AssemblyWriter::printGlobal(const GlobalVariable *GV) {
     PrintEscapedString(GV->getSection(), Out);
     Out << '"';
   }
+  maybePrintComdat(Out, *GV);
   if (GV->getAlignment())
     Out << ", align " << GV->getAlignment();
 
@@ -1486,14 +2355,15 @@ void AssemblyWriter::printAlias(const GlobalAlias *GA) {
     PrintLLVMName(Out, GA);
     Out << " = ";
   }
+  PrintLinkage(GA->getLinkage(), Out);
   PrintVisibility(GA->getVisibility(), Out);
   PrintDLLStorageClass(GA->getDLLStorageClass(), Out);
   PrintThreadLocalModel(GA->getThreadLocalMode(), Out);
+  if (GA->hasUnnamedAddr())
+    Out << "unnamed_addr ";
 
   Out << "alias ";
 
-  PrintLinkage(GA->getLinkage(), Out);
-
   const Constant *Aliasee = GA->getAliasee();
 
   if (!Aliasee) {
@@ -1507,6 +2377,10 @@ void AssemblyWriter::printAlias(const GlobalAlias *GA) {
   Out << '\n';
 }
 
+void AssemblyWriter::printComdat(const Comdat *C) {
+  C->print(Out);
+}
+
 void AssemblyWriter::printTypeIdentities() {
   if (TypePrinter.NumberedTypes.empty() &&
       TypePrinter.NamedTypes.empty())
@@ -1644,6 +2518,7 @@ void AssemblyWriter::printFunction(const Function *F) {
     PrintEscapedString(F->getSection(), Out);
     Out << '"';
   }
+  maybePrintComdat(Out, *F);
   if (F->getAlignment())
     Out << " align " << F->getAlignment();
   if (F->hasGC())
@@ -1652,6 +2527,11 @@ void AssemblyWriter::printFunction(const Function *F) {
     Out << " prefix ";
     writeOperand(F->getPrefixData(), true);
   }
+  if (F->hasPrologueData()) {
+    Out << " prologue ";
+    writeOperand(F->getPrologueData(), true);
+  }
+
   if (F->isDeclaration()) {
     Out << '\n';
   } else {
@@ -1660,6 +2540,9 @@ void AssemblyWriter::printFunction(const Function *F) {
     for (Function::const_iterator I = F->begin(), E = F->end(); I != E; ++I)
       printBasicBlock(I);
 
+    // Output the function's use-lists.
+    printUseLists(F);
+
     Out << "}\n";
   }
 
@@ -1783,6 +2666,9 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
       (isa<StoreInst>(I) && cast<StoreInst>(I).isAtomic()))
     Out << " atomic";
 
+  if (isa<AtomicCmpXchgInst>(I) && cast<AtomicCmpXchgInst>(I).isWeak())
+    Out << " weak";
+
   // If this is a volatile operation, print out the volatile marker.
   if ((isa<LoadInst>(I)  && cast<LoadInst>(I).isVolatile()) ||
       (isa<StoreInst>(I) && cast<StoreInst>(I).isVolatile()) ||
@@ -1920,6 +2806,14 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
         Out << ", ";
       writeParamOperand(CI->getArgOperand(op), PAL, op + 1);
     }
+
+    // Emit an ellipsis if this is a musttail call in a vararg function.  This
+    // is only to aid readability, musttail calls forward varargs by default.
+    if (CI->isMustTailCall() && CI->getParent() &&
+        CI->getParent()->getParent() &&
+        CI->getParent()->getParent()->isVarArg())
+      Out << ", ...";
+
     Out << ')';
     if (PAL.hasAttributes(AttributeSet::FunctionIndex))
       Out << " #" << Machine.getAttributeGroupSlot(PAL.getFnAttributes());
@@ -1974,7 +2868,13 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
     if (AI->isUsedWithInAlloca())
       Out << "inalloca ";
     TypePrinter.print(AI->getAllocatedType(), Out);
-    if (!AI->getArraySize() || AI->isArrayAllocation()) {
+
+    // Explicitly write the array size if the code is broken, if it's an array
+    // allocation, or if the type is not canonical for scalar allocations.  The
+    // latter case prevents the type from mutating when round-tripping through
+    // assembly.
+    if (!AI->getArraySize() || AI->isArrayAllocation() ||
+        !AI->getArraySize()->getType()->isIntegerTy(32)) {
       Out << ", ";
       writeOperand(AI->getArraySize(), true);
     }
@@ -1996,6 +2896,15 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
     Out << ", ";
     TypePrinter.print(I.getType(), Out);
   } else if (Operand) {   // Print the normal way.
+    if (const auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {
+      Out << ' ';
+      TypePrinter.print(GEP->getSourceElementType(), Out);
+      Out << ',';
+    } else if (const auto *LI = dyn_cast<LoadInst>(&I)) {
+      Out << ' ';
+      TypePrinter.print(LI->getType(), Out);
+      Out << ',';
+    }
 
     // PrintAllTypes - Instructions who have operands of all the same type
     // omit the type from all but the first operand.  If the instruction has
@@ -2052,7 +2961,7 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
   }
 
   // Print Metadata info.
-  SmallVector<std::pair<unsigned, MDNode*>, 4> InstMD;
+  SmallVector<std::pair<unsigned, MDNode *>, 4> InstMD;
   I.getAllMetadata(InstMD);
   if (!InstMD.empty()) {
     SmallVector<StringRef, 8> MDNames;
@@ -2072,32 +2981,10 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
   printInfoComment(I);
 }
 
-static void WriteMDNodeComment(const MDNode *Node,
-                               formatted_raw_ostream &Out) {
-  if (Node->getNumOperands() < 1)
-    return;
-
-  Value *Op = Node->getOperand(0);
-  if (!Op || !isa<ConstantInt>(Op) || cast<ConstantInt>(Op)->getBitWidth() < 32)
-    return;
-
-  DIDescriptor Desc(Node);
-  if (!Desc.Verify())
-    return;
-
-  unsigned Tag = Desc.getTag();
-  Out.PadToColumn(50);
-  if (dwarf::TagString(Tag)) {
-    Out << "; ";
-    Desc.print(Out);
-  } else if (Tag == dwarf::DW_TAG_user_base) {
-    Out << "; [ DW_TAG_user_base ]";
-  }
-}
-
 void AssemblyWriter::writeMDNode(unsigned Slot, const MDNode *Node) {
-  Out << '!' << Slot << " = metadata ";
+  Out << '!' << Slot << " = ";
   printMDNodeBody(Node);
+  Out << "\n";
 }
 
 void AssemblyWriter::writeAllMDNodes() {
@@ -2114,8 +3001,6 @@ void AssemblyWriter::writeAllMDNodes() {
 
 void AssemblyWriter::printMDNodeBody(const MDNode *Node) {
   WriteMDNodeBodyInternal(Out, Node, &TypePrinter, &Machine, TheModule);
-  WriteMDNodeComment(Node, Out);
-  Out << "\n";
 }
 
 void AssemblyWriter::writeAllAttributeGroups() {
@@ -2132,7 +3017,44 @@ void AssemblyWriter::writeAllAttributeGroups() {
         << I->first.getAsString(AttributeSet::FunctionIndex, true) << " }\n";
 }
 
-} // namespace llvm
+void AssemblyWriter::printUseListOrder(const UseListOrder &Order) {
+  bool IsInFunction = Machine.getFunction();
+  if (IsInFunction)
+    Out << "  ";
+
+  Out << "uselistorder";
+  if (const BasicBlock *BB =
+          IsInFunction ? nullptr : dyn_cast<BasicBlock>(Order.V)) {
+    Out << "_bb ";
+    writeOperand(BB->getParent(), false);
+    Out << ", ";
+    writeOperand(BB, false);
+  } else {
+    Out << " ";
+    writeOperand(Order.V, true);
+  }
+  Out << ", { ";
+
+  assert(Order.Shuffle.size() >= 2 && "Shuffle too small");
+  Out << Order.Shuffle[0];
+  for (unsigned I = 1, E = Order.Shuffle.size(); I != E; ++I)
+    Out << ", " << Order.Shuffle[I];
+  Out << " }\n";
+}
+
+void AssemblyWriter::printUseLists(const Function *F) {
+  auto hasMore =
+      [&]() { return !UseListOrders.empty() && UseListOrders.back().F == F; };
+  if (!hasMore())
+    // Nothing to do.
+    return;
+
+  Out << "\n; uselistorder directives\n";
+  while (hasMore()) {
+    printUseListOrder(UseListOrders.back());
+    UseListOrders.pop_back();
+  }
+}
 
 //===----------------------------------------------------------------------===//
 //                       External Interface declarations
@@ -2152,11 +3074,32 @@ void NamedMDNode::print(raw_ostream &ROS) const {
   W.printNamedMDNode(this);
 }
 
-void Type::print(raw_ostream &OS) const {
-  if (!this) {
-    OS << "<null Type>";
-    return;
+void Comdat::print(raw_ostream &ROS) const {
+  PrintLLVMName(ROS, getName(), ComdatPrefix);
+  ROS << " = comdat ";
+
+  switch (getSelectionKind()) {
+  case Comdat::Any:
+    ROS << "any";
+    break;
+  case Comdat::ExactMatch:
+    ROS << "exactmatch";
+    break;
+  case Comdat::Largest:
+    ROS << "largest";
+    break;
+  case Comdat::NoDuplicates:
+    ROS << "noduplicates";
+    break;
+  case Comdat::SameSize:
+    ROS << "samesize";
+    break;
   }
+
+  ROS << '\n';
+}
+
+void Type::print(raw_ostream &OS) const {
   TypePrinting TP;
   TP.print(const_cast<Type*>(this), OS);
 
@@ -2168,15 +3111,24 @@ void Type::print(raw_ostream &OS) const {
     }
 }
 
+static bool isReferencingMDNode(const Instruction &I) {
+  if (const auto *CI = dyn_cast<CallInst>(&I))
+    if (Function *F = CI->getCalledFunction())
+      if (F->isIntrinsic())
+        for (auto &Op : I.operands())
+          if (auto *V = dyn_cast_or_null<MetadataAsValue>(Op))
+            if (isa<MDNode>(V->getMetadata()))
+              return true;
+  return false;
+}
+
 void Value::print(raw_ostream &ROS) const {
-  if (!this) {
-    ROS << "printing a <null> value\n";
-    return;
-  }
   formatted_raw_ostream OS(ROS);
   if (const Instruction *I = dyn_cast<Instruction>(this)) {
     const Function *F = I->getParent() ? I->getParent()->getParent() : nullptr;
-    SlotTracker SlotTable(F);
+    SlotTracker SlotTable(
+        F,
+        /* ShouldInitializeAllMetadata */ isReferencingMDNode(*I));
     AssemblyWriter W(OS, SlotTable, getModuleFromVal(I), nullptr);
     W.printInstruction(*I);
   } else if (const BasicBlock *BB = dyn_cast<BasicBlock>(this)) {
@@ -2184,7 +3136,8 @@ void Value::print(raw_ostream &ROS) const {
     AssemblyWriter W(OS, SlotTable, getModuleFromVal(BB), nullptr);
     W.printBasicBlock(BB);
   } else if (const GlobalValue *GV = dyn_cast<GlobalValue>(this)) {
-    SlotTracker SlotTable(GV->getParent());
+    SlotTracker SlotTable(GV->getParent(),
+                          /* ShouldInitializeAllMetadata */ isa<Function>(GV));
     AssemblyWriter W(OS, SlotTable, GV->getParent(), nullptr);
     if (const GlobalVariable *V = dyn_cast<GlobalVariable>(GV))
       W.printGlobal(V);
@@ -2192,18 +3145,14 @@ void Value::print(raw_ostream &ROS) const {
       W.printFunction(F);
     else
       W.printAlias(cast<GlobalAlias>(GV));
-  } else if (const MDNode *N = dyn_cast<MDNode>(this)) {
-    const Function *F = N->getFunction();
-    SlotTracker SlotTable(F);
-    AssemblyWriter W(OS, SlotTable, F ? F->getParent() : nullptr, nullptr);
-    W.printMDNodeBody(N);
+  } else if (const MetadataAsValue *V = dyn_cast<MetadataAsValue>(this)) {
+    V->getMetadata()->print(ROS, getModuleFromVal(V));
   } else if (const Constant *C = dyn_cast<Constant>(this)) {
     TypePrinting TypePrinter;
     TypePrinter.print(C->getType(), OS);
     OS << ' ';
     WriteConstantInternal(OS, C, TypePrinter, nullptr, nullptr);
-  } else if (isa<InlineAsm>(this) || isa<MDString>(this) ||
-             isa<Argument>(this)) {
+  } else if (isa<InlineAsm>(this) || isa<Argument>(this)) {
     this->printAsOperand(OS);
   } else {
     llvm_unreachable("Unknown value to print out!");
@@ -2213,9 +3162,9 @@ void Value::print(raw_ostream &ROS) const {
 void Value::printAsOperand(raw_ostream &O, bool PrintType, const Module *M) const {
   // Fast path: Don't construct and populate a TypePrinting object if we
   // won't be needing any types printed.
-  if (!PrintType &&
-      ((!isa<Constant>(this) && !isa<MDNode>(this)) ||
-       hasName() || isa<GlobalValue>(this))) {
+  bool IsMetadata = isa<MetadataAsValue>(this);
+  if (!PrintType && ((!isa<Constant>(this) && !IsMetadata) || hasName() ||
+                     isa<GlobalValue>(this))) {
     WriteAsOperandInternal(O, this, nullptr, nullptr, M);
     return;
   }
@@ -2231,17 +3180,62 @@ void Value::printAsOperand(raw_ostream &O, bool PrintType, const Module *M) cons
     O << ' ';
   }
 
-  WriteAsOperandInternal(O, this, &TypePrinter, nullptr, M);
+  SlotTracker Machine(M, /* ShouldInitializeAllMetadata */ IsMetadata);
+  WriteAsOperandInternal(O, this, &TypePrinter, &Machine, M);
+}
+
+static void printMetadataImpl(raw_ostream &ROS, const Metadata &MD,
+                              const Module *M, bool OnlyAsOperand) {
+  formatted_raw_ostream OS(ROS);
+
+  auto *N = dyn_cast<MDNode>(&MD);
+  TypePrinting TypePrinter;
+  SlotTracker Machine(M, /* ShouldInitializeAllMetadata */ N);
+  if (M)
+    TypePrinter.incorporateTypes(*M);
+
+  WriteAsOperandInternal(OS, &MD, &TypePrinter, &Machine, M,
+                         /* FromValue */ true);
+  if (OnlyAsOperand || !N)
+    return;
+
+  OS << " = ";
+  WriteMDNodeBodyInternal(OS, N, &TypePrinter, &Machine, M);
+}
+
+void Metadata::printAsOperand(raw_ostream &OS, const Module *M) const {
+  printMetadataImpl(OS, *this, M, /* OnlyAsOperand */ true);
+}
+
+void Metadata::print(raw_ostream &OS, const Module *M) const {
+  printMetadataImpl(OS, *this, M, /* OnlyAsOperand */ false);
 }
 
 // Value::dump - allow easy printing of Values from the debugger.
+LLVM_DUMP_METHOD
 void Value::dump() const { print(dbgs()); dbgs() << '\n'; }
 
 // Type::dump - allow easy printing of Types from the debugger.
-void Type::dump() const { print(dbgs()); }
+LLVM_DUMP_METHOD
+void Type::dump() const { print(dbgs()); dbgs() << '\n'; }
 
 // Module::dump() - Allow printing of Modules from the debugger.
+LLVM_DUMP_METHOD
 void Module::dump() const { print(dbgs(), nullptr); }
 
+// \brief Allow printing of Comdats from the debugger.
+LLVM_DUMP_METHOD
+void Comdat::dump() const { print(dbgs()); }
+
 // NamedMDNode::dump() - Allow printing of NamedMDNodes from the debugger.
+LLVM_DUMP_METHOD
 void NamedMDNode::dump() const { print(dbgs()); }
+
+LLVM_DUMP_METHOD
+void Metadata::dump() const { dump(nullptr); }
+
+LLVM_DUMP_METHOD
+void Metadata::dump(const Module *M) const {
+  print(dbgs(), M);
+  dbgs() << '\n';
+}