[DebugInfo] Generate DWARF debug information for labels.

There are two forms for label debug information in DWARF format.

1. Labels in a non-inlined function:

DW_TAG_label
  DW_AT_name
  DW_AT_decl_file
  DW_AT_decl_line
  DW_AT_low_pc

2. Labels in an inlined function:

DW_TAG_label
  DW_AT_abstract_origin
  DW_AT_low_pc

We will collect label information from DBG_LABEL. Before every DBG_LABEL,
we will generate a temporary symbol to denote the location of the label.
The symbol could be used to get DW_AT_low_pc afterwards. So, we create a
mapping between 'inlined label' and DBG_LABEL MachineInstr in DebugHandlerBase.
The DBG_LABEL in the mapping is used to query the symbol before it.

The AbstractLabels in DwarfCompileUnit is used to process labels in inlined
functions.

We also keep a mapping between scope and labels in DwarfFile to help to
generate correct tree structure of DIEs.

It also generates label debug information under global isel.

Differential Revision: https://reviews.llvm.org/D45556

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338390 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h

@@ -208,6 +208,10 @@ public:
                                          const MDNode *Variable,
                                          const MDNode *Expr);
 
+  /// Build and insert a DBG_LABEL instructions specifying that \p Label is
+  /// given. Convert "llvm.dbg.label Label" to "DBG_LABEL Label".
+  MachineInstrBuilder buildDbgLabel(const MDNode *Label);
+
   /// Build and insert \p Res = G_FRAME_INDEX \p Idx
   ///
   /// G_FRAME_INDEX materializes the address of an alloca value or other

lib/CodeGen/AsmPrinter/CMakeLists.txt

@@ -5,7 +5,7 @@ add_llvm_library(LLVMAsmPrinter
   AsmPrinter.cpp
   AsmPrinterDwarf.cpp
   AsmPrinterInlineAsm.cpp
-  DbgValueHistoryCalculator.cpp
+  DbgEntityHistoryCalculator.cpp
   DebugHandlerBase.cpp
   DebugLocStream.cpp
   DIE.cpp

lib/CodeGen/AsmPrinter/CodeViewDebug.h

@@ -14,7 +14,7 @@
 #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_CODEVIEWDEBUG_H
 #define LLVM_LIB_CODEGEN_ASMPRINTER_CODEVIEWDEBUG_H
 
-#include "DbgValueHistoryCalculator.h"
+#include "DbgEntityHistoryCalculator.h"
 #include "DebugHandlerBase.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"

lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp → lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp

@@ -1,4 +1,4 @@
-//===- llvm/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp --------------===//
+//===- llvm/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp -------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -7,7 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "DbgValueHistoryCalculator.h"
+#include "DbgEntityHistoryCalculator.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallVector.h"
@@ -78,11 +78,17 @@ unsigned DbgValueHistoryMap::getRegisterForVar(InlinedVariable Var) const {
   return isDescribedByReg(*Ranges.back().first);
 }
 
+void DbgLabelInstrMap::addInstr(InlinedLabel Label, const MachineInstr &MI) {
+  assert(MI.isDebugLabel() && "not a DBG_LABEL");
+  LabelInstr[Label] = &MI;
+}
+
 namespace {
 
 // Maps physreg numbers to the variables they describe.
 using InlinedVariable = DbgValueHistoryMap::InlinedVariable;
 using RegDescribedVarsMap = std::map<unsigned, SmallVector<InlinedVariable, 1>>;
+using InlinedLabel = DbgLabelInstrMap::InlinedLabel;
 
 } // end anonymous namespace
 
@@ -187,9 +193,10 @@ static void collectChangingRegs(const MachineFunction *MF,
   }
 }
 
-void llvm::calculateDbgValueHistory(const MachineFunction *MF,
-                                    const TargetRegisterInfo *TRI,
-                                    DbgValueHistoryMap &Result) {
+void llvm::calculateDbgEntityHistory(const MachineFunction *MF,
+                                     const TargetRegisterInfo *TRI,
+                                     DbgValueHistoryMap &DbgValues,
+                                     DbgLabelInstrMap &DbgLabels) {
   BitVector ChangingRegs(TRI->getNumRegs());
   collectChangingRegs(MF, TRI, ChangingRegs);
 
@@ -210,14 +217,14 @@ void llvm::calculateDbgValueHistory(const MachineFunction *MF,
             // If this is a virtual register, only clobber it since it doesn't
             // have aliases.
             if (TRI->isVirtualRegister(MO.getReg()))
-              clobberRegisterUses(RegVars, MO.getReg(), Result, MI);
+              clobberRegisterUses(RegVars, MO.getReg(), DbgValues, MI);
             // If this is a register def operand, it may end a debug value
             // range.
             else {
               for (MCRegAliasIterator AI(MO.getReg(), TRI, true); AI.isValid();
                    ++AI)
                 if (ChangingRegs.test(*AI))
-                  clobberRegisterUses(RegVars, *AI, Result, MI);
+                  clobberRegisterUses(RegVars, *AI, DbgValues, MI);
             }
           } else if (MO.isRegMask()) {
             // If this is a register mask operand, clobber all debug values in
@@ -226,7 +233,7 @@ void llvm::calculateDbgValueHistory(const MachineFunction *MF,
               // Don't consider SP to be clobbered by register masks.
               if (unsigned(I) != SP && TRI->isPhysicalRegister(I) &&
                   MO.clobbersPhysReg(I)) {
-                clobberRegisterUses(RegVars, I, Result, MI);
+                clobberRegisterUses(RegVars, I, DbgValues, MI);
               }
             }
           }
@@ -234,26 +241,34 @@ void llvm::calculateDbgValueHistory(const MachineFunction *MF,
         continue;
       }
 
-      // Skip DBG_LABEL instructions.
-      if (MI.isDebugLabel())
-        continue;
-
-      assert(MI.getNumOperands() > 1 && "Invalid DBG_VALUE instruction!");
-      // Use the base variable (without any DW_OP_piece expressions)
-      // as index into History. The full variables including the
-      // piece expressions are attached to the MI.
-      const DILocalVariable *RawVar = MI.getDebugVariable();
-      assert(RawVar->isValidLocationForIntrinsic(MI.getDebugLoc()) &&
-             "Expected inlined-at fields to agree");
-      InlinedVariable Var(RawVar, MI.getDebugLoc()->getInlinedAt());
-
-      if (unsigned PrevReg = Result.getRegisterForVar(Var))
-        dropRegDescribedVar(RegVars, PrevReg, Var);
-
-      Result.startInstrRange(Var, MI);
-
-      if (unsigned NewReg = isDescribedByReg(MI))
-        addRegDescribedVar(RegVars, NewReg, Var);
+      if (MI.isDebugValue()) {
+        assert(MI.getNumOperands() > 1 && "Invalid DBG_VALUE instruction!");
+        // Use the base variable (without any DW_OP_piece expressions)
+        // as index into History. The full variables including the
+        // piece expressions are attached to the MI.
+        const DILocalVariable *RawVar = MI.getDebugVariable();
+        assert(RawVar->isValidLocationForIntrinsic(MI.getDebugLoc()) &&
+               "Expected inlined-at fields to agree");
+        InlinedVariable Var(RawVar, MI.getDebugLoc()->getInlinedAt());
+
+        if (unsigned PrevReg = DbgValues.getRegisterForVar(Var))
+          dropRegDescribedVar(RegVars, PrevReg, Var);
+
+        DbgValues.startInstrRange(Var, MI);
+
+        if (unsigned NewReg = isDescribedByReg(MI))
+          addRegDescribedVar(RegVars, NewReg, Var);
+      } else if (MI.isDebugLabel()) {
+        assert(MI.getNumOperands() == 1 && "Invalid DBG_LABEL instruction!");
+        const DILabel *RawLabel = MI.getDebugLabel();
+        assert(RawLabel->isValidLocationForIntrinsic(MI.getDebugLoc()) &&
+            "Expected inlined-at fields to agree");
+        // When collecting debug information for labels, there is no MCSymbol
+        // generated for it. So, we keep MachineInstr in DbgLabels in order
+        // to query MCSymbol afterward.
+        InlinedLabel L(RawLabel, MI.getDebugLoc()->getInlinedAt());
+        DbgLabels.addInstr(L, MI);
+      }
     }
 
     // Make sure locations for register-described variables are valid only
@@ -264,7 +279,7 @@ void llvm::calculateDbgValueHistory(const MachineFunction *MF,
         auto CurElem = I++; // CurElem can be erased below.
         if (TRI->isVirtualRegister(CurElem->first) ||
             ChangingRegs.test(CurElem->first))
-          clobberRegisterUses(RegVars, CurElem, Result, MBB.back());
+          clobberRegisterUses(RegVars, CurElem, DbgValues, MBB.back());
       }
     }
   }

lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h → lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.h

@@ -1,4 +1,4 @@
-//===- llvm/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h ------*- C++ -*-===//
+//===- llvm/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.h -----*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -58,9 +58,30 @@ public:
 #endif
 };
 
-void calculateDbgValueHistory(const MachineFunction *MF,
-                              const TargetRegisterInfo *TRI,
-                              DbgValueHistoryMap &Result);
+/// For each inlined instance of a source-level label, keep the corresponding
+/// DBG_LABEL instruction. The DBG_LABEL instruction could be used to generate
+/// a temporary (assembler) label before it.
+class DbgLabelInstrMap {
+public:
+  using InlinedLabel = std::pair<const DILabel *, const DILocation *>;
+  using InstrMap = MapVector<InlinedLabel, const MachineInstr *>;
+
+private:
+  InstrMap LabelInstr;
+
+public:
+  void  addInstr(InlinedLabel Label, const MachineInstr &MI);
+
+  bool empty() const { return LabelInstr.empty(); }
+  void clear() { LabelInstr.clear(); }
+  InstrMap::const_iterator begin() const { return LabelInstr.begin(); }
+  InstrMap::const_iterator end() const { return LabelInstr.end(); }
+};
+
+void calculateDbgEntityHistory(const MachineFunction *MF,
+                               const TargetRegisterInfo *TRI,
+                               DbgValueHistoryMap &DbgValues,
+                               DbgLabelInstrMap &DbgLabels);
 
 } // end namespace llvm
 

lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp

@@ -190,8 +190,9 @@ void DebugHandlerBase::beginFunction(const MachineFunction *MF) {
 
   // Calculate history for local variables.
   assert(DbgValues.empty() && "DbgValues map wasn't cleaned!");
-  calculateDbgValueHistory(MF, Asm->MF->getSubtarget().getRegisterInfo(),
-                           DbgValues);
+  assert(DbgLabels.empty() && "DbgLabels map wasn't cleaned!");
+  calculateDbgEntityHistory(MF, Asm->MF->getSubtarget().getRegisterInfo(),
+                            DbgValues, DbgLabels);
   LLVM_DEBUG(DbgValues.dump());
 
   // Request labels for the full history.
@@ -229,6 +230,12 @@ void DebugHandlerBase::beginFunction(const MachineFunction *MF) {
     }
   }
 
+  // Ensure there is a symbol before DBG_LABEL.
+  for (const auto &I : DbgLabels) {
+    const MachineInstr *MI = I.second;
+    requestLabelBeforeInsn(MI);
+  }
+
   PrevInstLoc = DebugLoc();
   PrevLabel = Asm->getFunctionBegin();
   beginFunctionImpl(MF);
@@ -296,6 +303,7 @@ void DebugHandlerBase::endFunction(const MachineFunction *MF) {
   if (hasDebugInfo(MMI, MF))
     endFunctionImpl(MF);
   DbgValues.clear();
+  DbgLabels.clear();
   LabelsBeforeInsn.clear();
   LabelsAfterInsn.clear();
 }

lib/CodeGen/AsmPrinter/DebugHandlerBase.h

@@ -16,7 +16,7 @@
 #define LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGHANDLERBASE_H
 
 #include "AsmPrinterHandler.h"
-#include "DbgValueHistoryCalculator.h"
+#include "DbgEntityHistoryCalculator.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/CodeGen/LexicalScopes.h"
 #include "llvm/CodeGen/MachineInstr.h"
@@ -82,6 +82,9 @@ protected:
   /// variable.  Variables are listed in order of appearance.
   DbgValueHistoryMap DbgValues;
 
+  /// Mapping of inlined labels and DBG_LABEL machine instruction.
+  DbgLabelInstrMap DbgLabels;
+
   /// Maps instruction with label emitted before instruction.
   /// FIXME: Make this private from DwarfDebug, we have the necessary accessors
   /// for it.

lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -506,6 +506,18 @@ DIE *DwarfCompileUnit::constructVariableDIE(DbgVariable &DV, bool Abstract) {
   return D;
 }
 
+DIE *DwarfCompileUnit::constructLabelDIE(DbgLabel &DL,
+                                         const LexicalScope &Scope) {
+  auto LabelDie = DIE::get(DIEValueAllocator, DL.getTag());
+  insertDIE(DL.getLabel(), LabelDie);
+  DL.setDIE(*LabelDie);
+
+  if (Scope.isAbstractScope())
+    applyLabelAttributes(DL, *LabelDie);
+
+  return LabelDie;
+}
+
 DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
                                                 bool Abstract) {
   // Define variable debug information entry.
@@ -699,6 +711,9 @@ DIE *DwarfCompileUnit::createScopeChildrenDIE(LexicalScope *Scope,
   if (HasNonScopeChildren)
     *HasNonScopeChildren = !Children.empty();
 
+  for (DbgLabel *DL : DU->getScopeLabels().lookup(Scope))
+    Children.push_back(constructLabelDIE(*DL, *Scope));
+
   for (LexicalScope *LS : Scope->getChildren())
     constructScopeDIE(LS, Children);
 
@@ -824,40 +839,52 @@ void DwarfCompileUnit::finishSubprogramDefinition(const DISubprogram *SP) {
   }
 }
 
-void DwarfCompileUnit::finishVariableDefinition(const DbgVariable &Var) {
-  DbgVariable *AbsVar = getExistingAbstractVariable(
-      InlinedVariable(Var.getVariable(), Var.getInlinedAt()));
-  auto *VariableDie = Var.getDIE();
-  if (AbsVar && AbsVar->getDIE()) {
-    addDIEEntry(*VariableDie, dwarf::DW_AT_abstract_origin,
-                      *AbsVar->getDIE());
-  } else
-    applyVariableAttributes(Var, *VariableDie);
-}
+void DwarfCompileUnit::finishEntityDefinition(const DbgEntity *Entity) {
+  DbgEntity *AbsEntity = getExistingAbstractEntity(Entity->getEntity());
+
+  auto *Die = Entity->getDIE();
+  /// Label may be used to generate DW_AT_low_pc, so put it outside
+  /// if/else block.
+  const DbgLabel *Label = nullptr;
+  if (AbsEntity && AbsEntity->getDIE()) {
+    addDIEEntry(*Die, dwarf::DW_AT_abstract_origin, *AbsEntity->getDIE());
+    Label = dyn_cast<const DbgLabel>(Entity);
+  } else {
+    if (const DbgVariable *Var = dyn_cast<const DbgVariable>(Entity))
+      applyVariableAttributes(*Var, *Die);
+    else if ((Label = dyn_cast<const DbgLabel>(Entity)))
+      applyLabelAttributes(*Label, *Die);
+    else
+      llvm_unreachable("DbgEntity must be DbgVariable or DbgLabel.");
+  }
 
-DbgVariable *DwarfCompileUnit::getExistingAbstractVariable(InlinedVariable IV) {
-  const DILocalVariable *Cleansed;
-  return getExistingAbstractVariable(IV, Cleansed);
+  if (Label) {
+    const MCSymbol *Sym = Label->getSymbol();
+    addLabelAddress(*Die, dwarf::DW_AT_low_pc, Sym);
+  }
 }
 
-// Find abstract variable, if any, associated with Var.
-DbgVariable *DwarfCompileUnit::getExistingAbstractVariable(
-    InlinedVariable IV, const DILocalVariable *&Cleansed) {
-  // More then one inlined variable corresponds to one abstract variable.
-  Cleansed = IV.first;
-  auto &AbstractVariables = getAbstractVariables();
-  auto I = AbstractVariables.find(Cleansed);
-  if (I != AbstractVariables.end())
+DbgEntity *DwarfCompileUnit::getExistingAbstractEntity(const DINode *Node) {
+  auto &AbstractEntities = getAbstractEntities();
+  auto I = AbstractEntities.find(Node);
+  if (I != AbstractEntities.end())
     return I->second.get();
   return nullptr;
 }
 
-void DwarfCompileUnit::createAbstractVariable(const DILocalVariable *Var,
-                                        LexicalScope *Scope) {
+void DwarfCompileUnit::createAbstractEntity(const DINode *Node,
+                                            LexicalScope *Scope) {
   assert(Scope && Scope->isAbstractScope());
-  auto AbsDbgVariable = llvm::make_unique<DbgVariable>(Var, /* IA */ nullptr);
-  DU->addScopeVariable(Scope, AbsDbgVariable.get());
-  getAbstractVariables()[Var] = std::move(AbsDbgVariable);
+  auto &Entity = getAbstractEntities()[Node];
+  if (isa<const DILocalVariable>(Node)) {
+    Entity = llvm::make_unique<DbgVariable>(
+                        cast<const DILocalVariable>(Node), nullptr /* IA */);;
+    DU->addScopeVariable(Scope, cast<DbgVariable>(Entity.get()));
+  } else if (isa<const DILabel>(Node)) {
+    Entity = llvm::make_unique<DbgLabel>(
+                        cast<const DILabel>(Node), nullptr /* IA */);
+    DU->addScopeLabel(Scope, cast<DbgLabel>(Entity.get()));
+  }
 }
 
 void DwarfCompileUnit::emitHeader(bool UseOffsets) {
@@ -1012,6 +1039,15 @@ void DwarfCompileUnit::applyVariableAttributes(const DbgVariable &Var,
     addFlag(VariableDie, dwarf::DW_AT_artificial);
 }
 
+void DwarfCompileUnit::applyLabelAttributes(const DbgLabel &Label,
+                                            DIE &LabelDie) {
+  StringRef Name = Label.getName();
+  if (!Name.empty())
+    addString(LabelDie, dwarf::DW_AT_name, Name);
+  const auto *DILabel = Label.getLabel();
+  addSourceLine(LabelDie, DILabel);
+}
+
 /// Add a Dwarf expression attribute data and value.
 void DwarfCompileUnit::addExpr(DIELoc &Die, dwarf::Form Form,
                                const MCExpr *Expr) {

lib/CodeGen/AsmPrinter/DwarfCompileUnit.h

@@ -14,7 +14,7 @@
 #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
 #define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFCOMPILEUNIT_H
 
-#include "DbgValueHistoryCalculator.h"
+#include "DbgEntityHistoryCalculator.h"
 #include "DwarfDebug.h"
 #include "DwarfUnit.h"
 #include "llvm/ADT/ArrayRef.h"
@@ -81,7 +81,7 @@ class DwarfCompileUnit final : public DwarfUnit {
   const MCSymbol *BaseAddress = nullptr;
 
   DenseMap<const MDNode *, DIE *> AbstractSPDies;
-  DenseMap<const MDNode *, std::unique_ptr<DbgVariable>> AbstractVariables;
+  DenseMap<const DINode *, std::unique_ptr<DbgEntity>> AbstractEntities;
 
   /// DWO ID for correlating skeleton and split units.
   uint64_t DWOId = 0;
@@ -98,10 +98,10 @@ class DwarfCompileUnit final : public DwarfUnit {
     return DU->getAbstractSPDies();
   }
 
-  DenseMap<const MDNode *, std::unique_ptr<DbgVariable>> &getAbstractVariables() {
+  DenseMap<const DINode *, std::unique_ptr<DbgEntity>> &getAbstractEntities() {
     if (isDwoUnit() && !DD->shareAcrossDWOCUs())
-      return AbstractVariables;
-    return DU->getAbstractVariables();
+      return AbstractEntities;
+    return DU->getAbstractEntities();
   }
 
 public:
@@ -194,6 +194,9 @@ public:
   DIE *constructVariableDIE(DbgVariable &DV, const LexicalScope &Scope,
                             DIE *&ObjectPointer);
 
+  /// Construct a DIE for the given DbgLabel.
+  DIE *constructLabelDIE(DbgLabel &DL, const LexicalScope &Scope);
+
   /// A helper function to create children of a Scope DIE.
   DIE *createScopeChildrenDIE(LexicalScope *Scope,
                               SmallVectorImpl<DIE *> &Children,
@@ -210,14 +213,12 @@ public:
   DIE *constructImportedEntityDIE(const DIImportedEntity *Module);
 
   void finishSubprogramDefinition(const DISubprogram *SP);
-  void finishVariableDefinition(const DbgVariable &Var);
+  void finishEntityDefinition(const DbgEntity *Entity);
 
   /// Find abstract variable associated with Var.
   using InlinedVariable = DbgValueHistoryMap::InlinedVariable;
-  DbgVariable *getExistingAbstractVariable(InlinedVariable IV,
-                                           const DILocalVariable *&Cleansed);
-  DbgVariable *getExistingAbstractVariable(InlinedVariable IV);
-  void createAbstractVariable(const DILocalVariable *Var, LexicalScope *Scope);
+  DbgEntity *getExistingAbstractEntity(const DINode *Node);
+  void createAbstractEntity(const DINode *Node, LexicalScope *Scope);
 
   /// Set the skeleton unit associated with this unit.
   void setSkeleton(DwarfCompileUnit &Skel) { Skeleton = &Skel; }
@@ -288,6 +289,8 @@ public:
   void applySubprogramAttributesToDefinition(const DISubprogram *SP,
                                              DIE &SPDie);
 
+  void applyLabelAttributes(const DbgLabel &Label, DIE &LabelDie);
+
   /// getRangeLists - Get the vector of range lists.
   const SmallVectorImpl<RangeSpanList> &getRangeLists() const {
     return (Skeleton ? Skeleton : this)->CURangeLists;

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -188,12 +188,12 @@ bool DebugLocDwarfExpression::isFrameRegister(const TargetRegisterInfo &TRI,
 }
 
 bool DbgVariable::isBlockByrefVariable() const {
-  assert(Var && "Invalid complex DbgVariable!");
-  return Var->getType().resolve()->isBlockByrefStruct();
+  assert(getVariable() && "Invalid complex DbgVariable!");
+  return getVariable()->getType().resolve()->isBlockByrefStruct();
 }
 
 const DIType *DbgVariable::getType() const {
-  DIType *Ty = Var->getType().resolve();
+  DIType *Ty = getVariable()->getType().resolve();
   // FIXME: isBlockByrefVariable should be reformulated in terms of complex
   // addresses instead.
   if (Ty->isBlockByrefStruct()) {
@@ -258,8 +258,8 @@ ArrayRef<DbgVariable::FrameIndexExpr> DbgVariable::getFrameIndexExprs() const {
 void DbgVariable::addMMIEntry(const DbgVariable &V) {
   assert(DebugLocListIndex == ~0U && !MInsn && "not an MMI entry");
   assert(V.DebugLocListIndex == ~0U && !V.MInsn && "not an MMI entry");
-  assert(V.Var == Var && "conflicting variable");
-  assert(V.IA == IA && "conflicting inlined-at location");
+  assert(V.getVariable() == getVariable() && "conflicting variable");
+  assert(V.getInlinedAt() == getInlinedAt() && "conflicting inlined-at location");
 
   assert(!FrameIndexExprs.empty() && "Expected an MMI entry");
   assert(!V.FrameIndexExprs.empty() && "Expected an MMI entry");
@@ -726,16 +726,16 @@ void DwarfDebug::beginModule() {
   }
 }
 
-void DwarfDebug::finishVariableDefinitions() {
-  for (const auto &Var : ConcreteVariables) {
-    DIE *VariableDie = Var->getDIE();
-    assert(VariableDie);
+void DwarfDebug::finishEntityDefinitions() {
+  for (const auto &Entity : ConcreteEntities) {
+    DIE *Die = Entity->getDIE();
+    assert(Die);
     // FIXME: Consider the time-space tradeoff of just storing the unit pointer
-    // in the ConcreteVariables list, rather than looking it up again here.
+    // in the ConcreteEntities list, rather than looking it up again here.
     // DIE::getUnit isn't simple - it walks parent pointers, etc.
-    DwarfCompileUnit *Unit = CUDieMap.lookup(VariableDie->getUnitDie());
+    DwarfCompileUnit *Unit = CUDieMap.lookup(Die->getUnitDie());
     assert(Unit);
-    Unit->finishVariableDefinition(*Var);
+    Unit->finishEntityDefinition(Entity.get());
   }
 }
 
@@ -753,7 +753,7 @@ void DwarfDebug::finalizeModuleInfo() {
 
   finishSubprogramDefinitions();
 
-  finishVariableDefinitions();
+  finishEntityDefinitions();
 
   // Include the DWO file name in the hash if there's more than one CU.
   // This handles ThinLTO's situation where imported CUs may very easily be
@@ -914,25 +914,24 @@ void DwarfDebug::endModule() {
   // FIXME: AbstractVariables.clear();
 }
 
-void DwarfDebug::ensureAbstractVariableIsCreated(DwarfCompileUnit &CU, InlinedVariable IV,
-                                                 const MDNode *ScopeNode) {
-  const DILocalVariable *Cleansed = nullptr;
-  if (CU.getExistingAbstractVariable(IV, Cleansed))
+void DwarfDebug::ensureAbstractEntityIsCreated(DwarfCompileUnit &CU,
+                                               const DINode *Node,
+                                               const MDNode *ScopeNode) {
+  if (CU.getExistingAbstractEntity(Node))
     return;
 
-  CU.createAbstractVariable(Cleansed, LScopes.getOrCreateAbstractScope(
+  CU.createAbstractEntity(Node, LScopes.getOrCreateAbstractScope(
                                        cast<DILocalScope>(ScopeNode)));
 }
 
-void DwarfDebug::ensureAbstractVariableIsCreatedIfScoped(DwarfCompileUnit &CU,
-    InlinedVariable IV, const MDNode *ScopeNode) {
-  const DILocalVariable *Cleansed = nullptr;
-  if (CU.getExistingAbstractVariable(IV, Cleansed))
+void DwarfDebug::ensureAbstractEntityIsCreatedIfScoped(DwarfCompileUnit &CU,
+    const DINode *Node, const MDNode *ScopeNode) {
+  if (CU.getExistingAbstractEntity(Node))
     return;
 
   if (LexicalScope *Scope =
           LScopes.findAbstractScope(cast_or_null<DILocalScope>(ScopeNode)))
-    CU.createAbstractVariable(Cleansed, Scope);
+    CU.createAbstractEntity(Node, Scope);
 }
 
 // Collect variable information from side table maintained by MF.
@@ -953,14 +952,14 @@ void DwarfDebug::collectVariableInfoFromMFTable(
     if (!Scope)
       continue;
 
-    ensureAbstractVariableIsCreatedIfScoped(TheCU, Var, Scope->getScopeNode());
+    ensureAbstractEntityIsCreatedIfScoped(TheCU, Var.first, Scope->getScopeNode());
     auto RegVar = llvm::make_unique<DbgVariable>(Var.first, Var.second);
     RegVar->initializeMMI(VI.Expr, VI.Slot);
     if (DbgVariable *DbgVar = MFVars.lookup(Var))
       DbgVar->addMMIEntry(*RegVar);
     else if (InfoHolder.addScopeVariable(Scope, RegVar.get())) {
       MFVars.insert({Var, RegVar.get()});
-      ConcreteVariables.push_back(std::move(RegVar));
+      ConcreteEntities.push_back(std::move(RegVar));
     }
   }
 }
@@ -1125,14 +1124,26 @@ DwarfDebug::buildLocationList(SmallVectorImpl<DebugLocEntry> &DebugLoc,
   }
 }
 
-DbgVariable *DwarfDebug::createConcreteVariable(DwarfCompileUnit &TheCU,
-                                                LexicalScope &Scope,
-                                                InlinedVariable IV) {
-  ensureAbstractVariableIsCreatedIfScoped(TheCU, IV, Scope.getScopeNode());
-  ConcreteVariables.push_back(
-      llvm::make_unique<DbgVariable>(IV.first, IV.second));
-  InfoHolder.addScopeVariable(&Scope, ConcreteVariables.back().get());
-  return ConcreteVariables.back().get();
+DbgEntity *DwarfDebug::createConcreteEntity(DwarfCompileUnit &TheCU,
+                                            LexicalScope &Scope,
+                                            const DINode *Node,
+                                            const DILocation *Location,
+                                            const MCSymbol *Sym) {
+  ensureAbstractEntityIsCreatedIfScoped(TheCU, Node, Scope.getScopeNode());
+  if (isa<const DILocalVariable>(Node)) {
+    ConcreteEntities.push_back(
+        llvm::make_unique<DbgVariable>(cast<const DILocalVariable>(Node),
+                                       Location));
+    InfoHolder.addScopeVariable(&Scope,
+        cast<DbgVariable>(ConcreteEntities.back().get()));
+  } else if (isa<const DILabel>(Node)) {
+    ConcreteEntities.push_back(
+        llvm::make_unique<DbgLabel>(cast<const DILabel>(Node),
+                                    Location, Sym));
+    InfoHolder.addScopeLabel(&Scope,
+        cast<DbgLabel>(ConcreteEntities.back().get()));
+  }
+  return ConcreteEntities.back().get();
 }
 
 /// Determine whether a *singular* DBG_VALUE is valid for the entirety of its
@@ -1194,9 +1205,9 @@ static bool validThroughout(LexicalScopes &LScopes,
 }
 
 // Find variables for each lexical scope.
-void DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU,
-                                     const DISubprogram *SP,
-                                     DenseSet<InlinedVariable> &Processed) {
+void DwarfDebug::collectEntityInfo(DwarfCompileUnit &TheCU,
+                                   const DISubprogram *SP,
+                                   DenseSet<InlinedVariable> &Processed) {
   // Grab the variable info that was squirreled away in the MMI side-table.
   collectVariableInfoFromMFTable(TheCU, Processed);
 
@@ -1220,7 +1231,8 @@ void DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU,
       continue;
 
     Processed.insert(IV);
-    DbgVariable *RegVar = createConcreteVariable(TheCU, *Scope, IV);
+    DbgVariable *RegVar = cast<DbgVariable>(createConcreteEntity(TheCU,
+                                            *Scope, IV.first, IV.second));
 
     const MachineInstr *MInsn = Ranges.front().first;
     assert(MInsn->isDebugValue() && "History must begin with debug value");
@@ -1253,13 +1265,44 @@ void DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU,
       Entry.finalize(*Asm, List, BT);
   }
 
-  // Collect info for variables that were optimized out.
+  // For each InlinedLabel collected from DBG_LABEL instructions, convert to
+  // DWARF-related DbgLabel.
+  for (const auto &I : DbgLabels) {
+    InlinedLabel IL = I.first;
+    const MachineInstr *MI = I.second;
+    if (MI == nullptr)
+      continue;
+
+    LexicalScope *Scope = nullptr;
+    // Get inlined DILocation if it is inlined label.
+    if (const DILocation *IA = IL.second)
+      Scope = LScopes.findInlinedScope(IL.first->getScope(), IA);
+    else
+      Scope = LScopes.findLexicalScope(IL.first->getScope());
+    // If label scope is not found then skip this label.
+    if (!Scope)
+      continue;
+
+    /// At this point, the temporary label is created.
+    /// Save the temporary label to DbgLabel entity to get the
+    /// actually address when generating Dwarf DIE.
+    MCSymbol *Sym = getLabelBeforeInsn(MI);
+    createConcreteEntity(TheCU, *Scope, IL.first, IL.second, Sym);
+  }
+
+  // Collect info for variables/labels that were optimized out.
   for (const DINode *DN : SP->getRetainedNodes()) {
+    LexicalScope *Scope = nullptr;
     if (auto *DV = dyn_cast<DILocalVariable>(DN)) {
-      if (Processed.insert(InlinedVariable(DV, nullptr)).second)
-        if (LexicalScope *Scope = LScopes.findLexicalScope(DV->getScope()))
-          createConcreteVariable(TheCU, *Scope, InlinedVariable(DV, nullptr));
+      if (!Processed.insert(InlinedVariable(DV, nullptr)).second)
+        continue;
+      Scope = LScopes.findLexicalScope(DV->getScope());
+    } else if (auto *DL = dyn_cast<DILabel>(DN)) {
+      Scope = LScopes.findLexicalScope(DL->getScope());
     }
+
+    if (Scope)
+      createConcreteEntity(TheCU, *Scope, DN, nullptr);
   }
 }
 
@@ -1417,7 +1460,7 @@ void DwarfDebug::endFunctionImpl(const MachineFunction *MF) {
   DwarfCompileUnit &TheCU = *CUMap.lookup(SP->getUnit());
 
   DenseSet<InlinedVariable> ProcessedVars;
-  collectVariableInfo(TheCU, SP, ProcessedVars);
+  collectEntityInfo(TheCU, SP, ProcessedVars);
 
   // Add the range of this function to the list of ranges for the CU.
   TheCU.addRange(RangeSpan(Asm->getFunctionBegin(), Asm->getFunctionEnd()));
@@ -1445,10 +1488,11 @@ void DwarfDebug::endFunctionImpl(const MachineFunction *MF) {
         // Collect info for variables that were optimized out.
         if (!ProcessedVars.insert(InlinedVariable(DV, nullptr)).second)
           continue;
-        ensureAbstractVariableIsCreated(TheCU, InlinedVariable(DV, nullptr),
-                                        DV->getScope());
+        ensureAbstractEntityIsCreated(TheCU, DV, DV->getScope());
         assert(LScopes.getAbstractScopesList().size() == NumAbstractScopes
-               && "ensureAbstractVariableIsCreated inserted abstract scopes");
+               && "ensureAbstractEntityIsCreated inserted abstract scopes");
+      } else if (auto *DL = dyn_cast<DILabel>(DN)) {
+        ensureAbstractEntityIsCreated(TheCU, DL, DL->getScope());
       }
     }
     constructAbstractSubprogramScopeDIE(TheCU, AScope);
@@ -1466,6 +1510,7 @@ void DwarfDebug::endFunctionImpl(const MachineFunction *MF) {
   // DbgVariables except those that are also in AbstractVariables (since they
   // can be used cross-function)
   InfoHolder.getScopeVariables().clear();
+  InfoHolder.getScopeLabels().clear();
   PrevLabel = nullptr;
   CurFn = nullptr;
 }

lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -15,7 +15,7 @@
 #define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFDEBUG_H
 
 #include "AddressPool.h"
-#include "DbgValueHistoryCalculator.h"
+#include "DbgEntityHistoryCalculator.h"
 #include "DebugHandlerBase.h"
 #include "DebugLocStream.h"
 #include "DwarfFile.h"
@@ -61,6 +61,46 @@ class MCSymbol;
 class MDNode;
 class Module;
 
+//===----------------------------------------------------------------------===//
+/// This class is defined as the common parent of DbgVariable and DbgLabel
+/// such that it could levarage polymorphism to extract common code for
+/// DbgVariable and DbgLabel.
+class DbgEntity {
+  const DINode *Entity;
+  const DILocation *InlinedAt;
+  DIE *TheDIE = nullptr;
+  unsigned SubclassID;
+
+public:
+  enum DbgEntityKind {
+    DbgVariableKind,
+    DbgLabelKind
+  };
+
+  DbgEntity(const DINode *N, const DILocation *IA, unsigned ID)
+    : Entity(N), InlinedAt(IA), SubclassID(ID) {}
+
+  /// Accessors.
+  /// @{
+  const DINode *getEntity() const { return Entity; }
+  const DILocation *getInlinedAt() const { return InlinedAt; }
+  DIE *getDIE() const { return TheDIE; }
+  unsigned getDbgEntityID() const { return SubclassID; }
+  /// @}
+
+  void setDIE(DIE &D) { TheDIE = &D; }
+
+  static bool classof(const DbgEntity *N) {
+    switch (N->getDbgEntityID()) {
+    default:
+      return false;
+    case DbgVariableKind:
+    case DbgLabelKind:
+      return true;
+    }
+  }
+};
+
 //===----------------------------------------------------------------------===//
 /// This class is used to track local variable information.
 ///
@@ -73,10 +113,7 @@ class Module;
 /// single instruction use \a MInsn and (optionally) a single entry of \a Expr.
 ///
 /// Variables that have been optimized out use none of these fields.
-class DbgVariable {
-  const DILocalVariable *Var;                /// Variable Descriptor.
-  const DILocation *IA;                      /// Inlined at location.
-  DIE *TheDIE = nullptr;                     /// Variable DIE.
+class DbgVariable : public DbgEntity {
   unsigned DebugLocListIndex = ~0u;          /// Offset in DebugLocs.
   const MachineInstr *MInsn = nullptr;       /// DBG_VALUE instruction.
 
@@ -93,7 +130,7 @@ public:
   /// Creates a variable without any DW_AT_location.  Call \a initializeMMI()
   /// for MMI entries, or \a initializeDbgValue() for DBG_VALUE instructions.
   DbgVariable(const DILocalVariable *V, const DILocation *IA)
-      : Var(V), IA(IA) {}
+      : DbgEntity(V, IA, DbgVariableKind) {}
 
   /// Initialize from the MMI table.
   void initializeMMI(const DIExpression *E, int FI) {
@@ -111,8 +148,9 @@ public:
     assert(FrameIndexExprs.empty() && "Already initialized?");
     assert(!MInsn && "Already initialized?");
 
-    assert(Var == DbgValue->getDebugVariable() && "Wrong variable");
-    assert(IA == DbgValue->getDebugLoc()->getInlinedAt() && "Wrong inlined-at");
+    assert(getVariable() == DbgValue->getDebugVariable() && "Wrong variable");
+    assert(getInlinedAt() == DbgValue->getDebugLoc()->getInlinedAt() &&
+           "Wrong inlined-at");
 
     MInsn = DbgValue;
     if (auto *E = DbgValue->getDebugExpression())
@@ -121,19 +159,18 @@ public:
   }
 
   // Accessors.
-  const DILocalVariable *getVariable() const { return Var; }
-  const DILocation *getInlinedAt() const { return IA; }
+  const DILocalVariable *getVariable() const {
+    return cast<DILocalVariable>(getEntity());
+  }
 
   const DIExpression *getSingleExpression() const {
     assert(MInsn && FrameIndexExprs.size() <= 1);
     return FrameIndexExprs.size() ? FrameIndexExprs[0].Expr : nullptr;
   }
 
-  void setDIE(DIE &D) { TheDIE = &D; }
-  DIE *getDIE() const { return TheDIE; }
   void setDebugLocListIndex(unsigned O) { DebugLocListIndex = O; }
   unsigned getDebugLocListIndex() const { return DebugLocListIndex; }
-  StringRef getName() const { return Var->getName(); }
+  StringRef getName() const { return getVariable()->getName(); }
   const MachineInstr *getMInsn() const { return MInsn; }
   /// Get the FI entries, sorted by fragment offset.
   ArrayRef<FrameIndexExpr> getFrameIndexExprs() const;
@@ -143,7 +180,7 @@ public:
   // Translate tag to proper Dwarf tag.
   dwarf::Tag getTag() const {
     // FIXME: Why don't we just infer this tag and store it all along?
-    if (Var->isParameter())
+    if (getVariable()->isParameter())
       return dwarf::DW_TAG_formal_parameter;
 
     return dwarf::DW_TAG_variable;
@@ -151,7 +188,7 @@ public:
 
   /// Return true if DbgVariable is artificial.
   bool isArtificial() const {
-    if (Var->isArtificial())
+    if (getVariable()->isArtificial())
       return true;
     if (getType()->isArtificial())
       return true;
@@ -159,7 +196,7 @@ public:
   }
 
   bool isObjectPointer() const {
-    if (Var->isObjectPointer())
+    if (getVariable()->isObjectPointer())
       return true;
     if (getType()->isObjectPointer())
       return true;
@@ -178,6 +215,45 @@ public:
   bool isBlockByrefVariable() const;
   const DIType *getType() const;
 
+  static bool classof(const DbgEntity *N) {
+    return N->getDbgEntityID() == DbgVariableKind;
+  }
+
+private:
+  template <typename T> T *resolve(TypedDINodeRef<T> Ref) const {
+    return Ref.resolve();
+  }
+};
+
+//===----------------------------------------------------------------------===//
+/// This class is used to track label information.
+///
+/// Labels are collected from \c DBG_LABEL instructions.
+class DbgLabel : public DbgEntity {
+  const MCSymbol *Sym;                  /// Symbol before DBG_LABEL instruction.
+
+public:
+  /// We need MCSymbol information to generate DW_AT_low_pc.
+  DbgLabel(const DILabel *L, const DILocation *IA, const MCSymbol *Sym = nullptr)
+      : DbgEntity(L, IA, DbgLabelKind), Sym(Sym) {}
+
+  /// Accessors.
+  /// @{
+  const DILabel *getLabel() const { return cast<DILabel>(getEntity()); }
+  const MCSymbol *getSymbol() const { return Sym; }
+
+  StringRef getName() const { return getLabel()->getName(); }
+  /// @}
+
+  /// Translate tag to proper Dwarf tag.
+  dwarf::Tag getTag() const {
+    return dwarf::DW_TAG_label;
+  }
+
+  static bool classof(const DbgEntity *N) {
+    return N->getDbgEntityID() == DbgLabelKind;
+  }
+
 private:
   template <typename T> T *resolve(TypedDINodeRef<T> Ref) const {
     return Ref.resolve();
@@ -217,8 +293,8 @@ class DwarfDebug : public DebugHandlerBase {
   /// Size of each symbol emitted (for those symbols that have a specific size).
   DenseMap<const MCSymbol *, uint64_t> SymSize;
 
-  /// Collection of abstract variables.
-  SmallVector<std::unique_ptr<DbgVariable>, 64> ConcreteVariables;
+  /// Collection of abstract variables/labels.
+  SmallVector<std::unique_ptr<DbgEntity>, 64> ConcreteEntities;
 
   /// Collection of DebugLocEntry. Stored in a linked list so that DIELocLists
   /// can refer to them in spite of insertions into this list.
@@ -333,14 +409,20 @@ class DwarfDebug : public DebugHandlerBase {
   }
 
   using InlinedVariable = DbgValueHistoryMap::InlinedVariable;
+  using InlinedLabel = DbgLabelInstrMap::InlinedLabel;
 
-  void ensureAbstractVariableIsCreated(DwarfCompileUnit &CU, InlinedVariable IV,
-                                       const MDNode *Scope);
-  void ensureAbstractVariableIsCreatedIfScoped(DwarfCompileUnit &CU, InlinedVariable IV,
-                                               const MDNode *Scope);
+  void ensureAbstractEntityIsCreated(DwarfCompileUnit &CU,
+                                     const DINode *Node,
+                                     const MDNode *Scope);
+  void ensureAbstractEntityIsCreatedIfScoped(DwarfCompileUnit &CU,
+                                             const DINode *Node,
+                                             const MDNode *Scope);
 
-  DbgVariable *createConcreteVariable(DwarfCompileUnit &TheCU,
-                                      LexicalScope &Scope, InlinedVariable IV);
+  DbgEntity *createConcreteEntity(DwarfCompileUnit &TheCU,
+                                  LexicalScope &Scope,
+                                  const DINode *Node,
+                                  const DILocation *Location,
+                                  const MCSymbol *Sym = nullptr);
 
   /// Construct a DIE for this abstract scope.
   void constructAbstractSubprogramScopeDIE(DwarfCompileUnit &SrcCU, LexicalScope *Scope);
@@ -349,7 +431,7 @@ class DwarfDebug : public DebugHandlerBase {
   void addAccelNameImpl(AccelTable<DataT> &AppleAccel, StringRef Name,
                         const DIE &Die);
 
-  void finishVariableDefinitions();
+  void finishEntityDefinitions();
 
   void finishSubprogramDefinitions();
 
@@ -466,8 +548,8 @@ class DwarfDebug : public DebugHandlerBase {
                         unsigned Flags);
 
   /// Populate LexicalScope entries with variables' info.
-  void collectVariableInfo(DwarfCompileUnit &TheCU, const DISubprogram *SP,
-                           DenseSet<InlinedVariable> &ProcessedVars);
+  void collectEntityInfo(DwarfCompileUnit &TheCU, const DISubprogram *SP,
+                         DenseSet<InlinedVariable> &ProcessedVars);
 
   /// Build the location list for all DBG_VALUEs in the
   /// function that describe the same variable.

lib/CodeGen/AsmPrinter/DwarfFile.cpp

@@ -98,3 +98,8 @@ bool DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
   }
   return true;
 }
+
+void DwarfFile::addScopeLabel(LexicalScope *LS, DbgLabel *Label) {
+  SmallVectorImpl<DbgLabel *> &Labels = ScopeLabels[LS];
+  Labels.push_back(Label);
+}

lib/CodeGen/AsmPrinter/DwarfFile.h

@@ -24,7 +24,9 @@
 namespace llvm {
 
 class AsmPrinter;
+class DbgEntity;
 class DbgVariable;
+class DbgLabel;
 class DwarfCompileUnit;
 class DwarfUnit;
 class LexicalScope;
@@ -62,9 +64,13 @@ class DwarfFile {
   /// Collection of DbgVariables of each lexical scope.
   DenseMap<LexicalScope *, ScopeVars> ScopeVariables;
 
+  /// Collection of DbgLabels of each lexical scope.
+  using LabelList = SmallVector<DbgLabel *, 4>;
+  DenseMap<LexicalScope *, LabelList> ScopeLabels;
+
   // Collection of abstract subprogram DIEs.
   DenseMap<const MDNode *, DIE *> AbstractSPDies;
-  DenseMap<const MDNode *, std::unique_ptr<DbgVariable>> AbstractVariables;
+  DenseMap<const DINode *, std::unique_ptr<DbgEntity>> AbstractEntities;
 
   /// Maps MDNodes for type system with the corresponding DIEs. These DIEs can
   /// be shared across CUs, that is why we keep the map here instead
@@ -122,16 +128,22 @@ public:
   /// \returns false if the variable was merged with a previous one.
   bool addScopeVariable(LexicalScope *LS, DbgVariable *Var);
 
+  void addScopeLabel(LexicalScope *LS, DbgLabel *Label);
+
   DenseMap<LexicalScope *, ScopeVars> &getScopeVariables() {
     return ScopeVariables;
   }
 
+  DenseMap<LexicalScope *, LabelList> &getScopeLabels() {
+    return ScopeLabels;
+  }
+
   DenseMap<const MDNode *, DIE *> &getAbstractSPDies() {
     return AbstractSPDies;
   }
 
-  DenseMap<const MDNode *, std::unique_ptr<DbgVariable>> &getAbstractVariables() {
-    return AbstractVariables;
+  DenseMap<const DINode *, std::unique_ptr<DbgEntity>> &getAbstractEntities() {
+    return AbstractEntities;
   }
 
   void insertDIE(const MDNode *TypeMD, DIE *Die) {

lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -401,6 +401,12 @@ void DwarfUnit::addSourceLine(DIE &Die, const DISubprogram *SP) {
   addSourceLine(Die, SP->getLine(), SP->getFile());
 }
 
+void DwarfUnit::addSourceLine(DIE &Die, const DILabel *L) {
+  assert(L);
+
+  addSourceLine(Die, L->getLine(), L->getFile());
+}
+
 void DwarfUnit::addSourceLine(DIE &Die, const DIType *Ty) {
   assert(Ty);
 

lib/CodeGen/AsmPrinter/DwarfUnit.h

@@ -213,6 +213,7 @@ public:
   void addSourceLine(DIE &Die, const DILocalVariable *V);
   void addSourceLine(DIE &Die, const DIGlobalVariable *G);
   void addSourceLine(DIE &Die, const DISubprogram *SP);
+  void addSourceLine(DIE &Die, const DILabel *L);
   void addSourceLine(DIE &Die, const DIType *Ty);
   void addSourceLine(DIE &Die, const DIObjCProperty *Ty);
 

lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -766,6 +766,17 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
                                      DI.getVariable(), DI.getExpression());
     return true;
   }
+  case Intrinsic::dbg_label: {
+    const DbgLabelInst &DI = cast<DbgLabelInst>(CI);
+    assert(DI.getLabel() && "Missing label");
+
+    assert(DI.getLabel()->isValidLocationForIntrinsic(
+               MIRBuilder.getDebugLoc()) &&
+           "Expected inlined-at fields to agree");
+
+    MIRBuilder.buildDbgLabel(DI.getLabel());
+    return true;
+  }
   case Intrinsic::vaend:
     // No target I know of cares about va_end. Certainly no in-tree target
     // does. Simplest intrinsic ever!

lib/CodeGen/GlobalISel/MachineIRBuilder.cpp

@@ -149,6 +149,15 @@ MachineInstrBuilder MachineIRBuilderBase::buildConstDbgValue(
   return MIB.addImm(0).addMetadata(Variable).addMetadata(Expr);
 }
 
+MachineInstrBuilder MachineIRBuilderBase::buildDbgLabel(const MDNode *Label) {
+  assert(isa<DILabel>(Label) && "not a label");
+  assert(cast<DILabel>(Label)->isValidLocationForIntrinsic(State.DL) &&
+         "Expected inlined-at fields to agree");
+  auto MIB = buildInstr(TargetOpcode::DBG_LABEL);
+
+  return MIB.addMetadata(Label);
+}
+
 MachineInstrBuilder MachineIRBuilderBase::buildFrameIndex(unsigned Res,
                                                           int Idx) {
   assert(getMRI()->getType(Res).isPointer() && "invalid operand type");

test/DebugInfo/Generic/debug-label-inline.ll

@@ -0,0 +1,50 @@
+; RUN: llc -O2 -filetype=obj -o - %s | llvm-dwarfdump -v - | FileCheck %s
+;
+; CHECK: .debug_info contents:
+; CHECK: [[LABEL_ORIGIN:0x[0-9a-zA-Z]+]]:{{ *}}DW_TAG_label
+; CHECK-NEXT: DW_AT_name [DW_FORM_strp] {{.*}}"top"
+; CHECK-NEXT: DW_AT_decl_file [DW_FORM_data1] {{.*}}debug-label-inline.c
+; CHECK-NEXT: DW_AT_decl_line [DW_FORM_data1] {{.*}}8
+; CHECK: DW_TAG_label
+; CHECK-NEXT: DW_AT_abstract_origin [DW_FORM_ref4] {{.*}}{[[LABEL_ORIGIN]]} "top"
+; CHECK-NEXT: DW_AT_low_pc [DW_FORM_addr] {{.*}}{{0x[0-9a-f]+}}
+
+source_filename = "debug-label-inline.c"
+
+@ga = external local_unnamed_addr global i32, align 4
+@gb = external local_unnamed_addr global i32, align 4
+
+define i32 @f2() local_unnamed_addr #0 !dbg !4 {
+entry:
+  %0 = load i32, i32* @ga, align 4, !dbg !1
+  %1 = load i32, i32* @gb, align 4, !dbg !1
+  call void @llvm.dbg.label(metadata !15), !dbg !17
+  %add.i = add nsw i32 %1, %0, !dbg !18
+  ret i32 %add.i, !dbg !1
+}
+
+declare void @llvm.dbg.label(metadata)
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+attributes #0 = { nounwind readonly }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !6, isOptimized: true, emissionKind: FullDebug, enums: !2)
+!1 = !DILocation(line: 18, scope: !4)
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = distinct !DISubprogram(name: "f2", scope: !6, file: !6, line: 15, type: !7, isLocal: false, isDefinition: true, scopeLine: 15, isOptimized: true, unit: !0, retainedNodes: !2)
+!6 = !DIFile(filename: "debug-label-inline.c", directory: "./")
+!7 = !DISubroutineType(types: !8)
+!8 = !{!10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = distinct !DISubprogram(name: "f1", scope: !6, file: !6, line: 5, type: !12, isLocal: false, isDefinition: true, scopeLine: 5, isOptimized: true, unit: !0, retainedNodes: !14)
+!12 = !DISubroutineType(types: !13)
+!13 = !{!10, !10, !10}
+!14 = !{!15}
+!15 = !DILabel(scope: !11, name: "top", file: !6, line: 8)
+!16 = distinct !DILocation(line: 18, scope: !4)
+!17 = !DILocation(line: 8, scope: !11, inlinedAt: !16)
+!18 = !DILocation(line: 9, scope: !11, inlinedAt: !16)

test/DebugInfo/Generic/debug-label.ll

@@ -0,0 +1,76 @@
+; RUN: llc -fast-isel=false -O0 -filetype=obj -o - %s | llvm-dwarfdump -v - | FileCheck %s
+;
+; CHECK: .debug_info contents:
+; CHECK: DW_TAG_label
+; CHECK-NEXT: DW_AT_name [DW_FORM_strp] {{.*}}"top"
+; CHECK-NEXT: DW_AT_decl_file [DW_FORM_data1] {{.*}}debug-label.c
+; CHECK-NEXT: DW_AT_decl_line [DW_FORM_data1] {{.*}}4
+; CHECK-NEXT: DW_AT_low_pc [DW_FORM_addr] {{.*}}{{0x[0-9a-f]+}}
+; CHECK: DW_TAG_label
+; CHECK-NEXT: DW_AT_name [DW_FORM_strp] {{.*}}"done"
+; CHECK-NEXT: DW_AT_decl_file [DW_FORM_data1] {{.*}}debug-label.c
+; CHECK-NEXT: DW_AT_decl_line [DW_FORM_data1] {{.*}}7
+; CHECK-NEXT: DW_AT_low_pc [DW_FORM_addr] {{.*}}{{0x[0-9a-f]+}}
+;
+; RUN: llc -fast-isel=false -O0 -o - %s | FileCheck %s -check-prefix=ASM
+;
+; ASM: [[TOP_LOW_PC:[.0-9a-zA-Z]+]]:{{[[:space:]].*}}DEBUG_LABEL: foo:top
+; ASM: [[DONE_LOW_PC:[.0-9a-zA-Z]+]]:{{[[:space:]].*}}DEBUG_LABEL: foo:done
+; ASM-LABEL: .debug_str
+; ASM: [[TOP_LABEL:[.0-9a-zA-Z]+]]:{{[[:space:]].*}}"top"
+; ASM: [[DONE_LABEL:[.0-9a-zA-Z]+]]:{{[[:space:]].*}}"done"
+; ASM-LABEL: .debug_info
+; ASM: DW_TAG_label
+; ASM-NEXT: [[TOP_LABEL]] # DW_AT_name
+; ASM-NEXT: 1 # DW_AT_decl_file
+; ASM-NEXT: 4 # DW_AT_decl_line
+; ASM-NEXT: [[TOP_LOW_PC]] # DW_AT_low_pc
+; ASM: DW_TAG_label
+; ASM-NEXT: [[DONE_LABEL]] # DW_AT_name
+; ASM-NEXT: 1 # DW_AT_decl_file
+; ASM-NEXT: 7 # DW_AT_decl_line
+; ASM-NEXT: [[DONE_LOW_PC]] # DW_AT_low_pc
+
+source_filename = "debug-label.c"
+
+define dso_local i32 @foo(i32 %a, i32 %b) !dbg !6 {
+entry:
+  %a.addr = alloca i32, align 4
+  %b.addr = alloca i32, align 4
+  %sum = alloca i32, align 4
+  store i32 %a, i32* %a.addr, align 4
+  store i32 %b, i32* %b.addr, align 4
+  br label %top
+
+top:
+  call void @llvm.dbg.label(metadata !10), !dbg !11
+  %0 = load i32, i32* %a.addr, align 4
+  %1 = load i32, i32* %b.addr, align 4
+  %add = add nsw i32 %0, %1
+  store i32 %add, i32* %sum, align 4
+  br label %done
+
+done:
+  call void @llvm.dbg.label(metadata !12), !dbg !13
+  %2 = load i32, i32* %sum, align 4
+  ret i32 %2, !dbg !14
+}
+
+declare void @llvm.dbg.label(metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: false, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "debug-label.c", directory: "./")
+!2 = !{}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 2, isOptimized: false, unit: !0, retainedNodes: !2)
+!7 = !DISubroutineType(types: !8)
+!8 = !{!9, !9, !9}
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !DILabel(scope: !6, name: "top", file: !1, line: 4)
+!11 = !DILocation(line: 4, column: 1, scope: !6)
+!12 = !DILabel(scope: !6, name: "done", file: !1, line: 7)
+!13 = !DILocation(line: 7, column: 1, scope: !6)
+!14 = !DILocation(line: 8, column: 3, scope: !6)