[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.

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

Patch by Hsiangkai Wang.

llvm-svn: 337799

Author: ShivaChen

llvm/include/llvm/IR/InstVisitor.h

@@ -213,7 +213,7 @@ class InstVisitor {
   // Handle the special instrinsic instruction classes.
   RetTy visitDbgDeclareInst(DbgDeclareInst &I)    { DELEGATE(DbgInfoIntrinsic);}
   RetTy visitDbgValueInst(DbgValueInst &I)        { DELEGATE(DbgInfoIntrinsic);}
-  RetTy visitDbgLabelInst(DbgLabelInst &I)        { DELEGATE(DbgInfoIntrinsic);}
+  RetTy visitDbgLabelInst(DbgLabelInst &I)        { DELEGATE(IntrinsicInst);}
   RetTy visitDbgInfoIntrinsic(DbgInfoIntrinsic &I) { DELEGATE(IntrinsicInst); }
   RetTy visitMemSetInst(MemSetInst &I)            { DELEGATE(MemIntrinsic); }
   RetTy visitMemCpyInst(MemCpyInst &I)            { DELEGATE(MemTransferInst); }

llvm/include/llvm/IR/IntrinsicInst.h

@@ -104,7 +104,6 @@ namespace llvm {
       case Intrinsic::dbg_declare:
       case Intrinsic::dbg_value:
       case Intrinsic::dbg_addr:
-      case Intrinsic::dbg_label:
         return true;
       default: return false;
       }
@@ -165,7 +164,7 @@ namespace llvm {
   };
 
   /// This represents the llvm.dbg.label instruction.
-  class DbgLabelInst : public DbgInfoIntrinsic {
+  class DbgLabelInst : public IntrinsicInst {
   public:
     DILabel *getLabel() const {
       return cast<DILabel>(getRawVariable());

llvm/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

llvm/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"

llvm/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp renamed to llvm/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
@@ -226,34 +233,42 @@ 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);
               }
             }
           }
         }
         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());
       }
     }
   }

llvm/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.h renamed to llvm/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 @@ class DbgValueHistoryMap {
 #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
 

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();
 }

llvm/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 @@ class DebugHandlerBase : public AsmPrinterHandler {
   /// 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.

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -502,6 +502,18 @@ 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.
@@ -692,6 +704,9 @@ 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);
 
@@ -817,40 +832,52 @@ 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());
 
-DbgVariable *DwarfCompileUnit::getExistingAbstractVariable(InlinedVariable IV) {
-  const DILocalVariable *Cleansed;
-  return getExistingAbstractVariable(IV, Cleansed);
+  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.");
+  }
+
+  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) {
@@ -1005,6 +1032,15 @@ 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) {