[DebugInfo] Add DILabel metadata and intrinsic llvm.dbg.label.

In order to set breakpoints on labels and list source code around
labels, we need collect debug information for labels, i.e., label
name, the function label belong, line number in the file, and the
address label located. In order to keep these information in LLVM
IR and to allow backend to generate debug information correctly.
We create a new kind of metadata for labels, DILabel. The format
of DILabel is

!DILabel(scope: !1, name: "foo", file: !2, line: 3)

We hope to keep debug information as much as possible even the
code is optimized. So, we create a new kind of intrinsic for label
metadata to avoid the metadata is eliminated with basic block.
The intrinsic will keep existing if we keep it from optimized out.
The format of the intrinsic is

llvm.dbg.label(metadata !1)

It has only one argument, that is the DILabel metadata. The
intrinsic will follow the label immediately. Backend could get the
label metadata through the intrinsic's parameter.

We also create DIBuilder API for labels to be used by Frontend.
Frontend could use createLabel() to allocate DILabel objects, and use
insertLabel() to insert llvm.dbg.label intrinsic in LLVM IR.

Differential Revision: https://reviews.llvm.org/D45024

Patch by Hsiangkai Wang.

llvm-svn: 331841

llvm/.gitattributes

@@ -1,6 +1,11 @@
 # binary files
 test/Object/Inputs/*.a-* binary
-test/tools/dsymutil/Inputs/* binary
+test/tools/dsymutil/Inputs/*.o binary
+test/tools/dsymutil/Inputs/*.a binary
+test/tools/dsymutil/Inputs/*.i386 binary
+test/tools/dsymutil/Inputs/*.x86_64 binary
+test/tools/dsymutil/Inputs/*.armv7m binary
+test/tools/dsymutil/Inputs/*.dylib binary
 test/tools/llvm-ar/Inputs/*.lib binary
 test/tools/llvm-objdump/Inputs/*.a binary
 test/tools/llvm-rc/Inputs/* binary

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -155,6 +155,7 @@ class TargetTransformInfoImplBase {
     case Intrinsic::sideeffect:
     case Intrinsic::dbg_declare:
     case Intrinsic::dbg_value:
+    case Intrinsic::dbg_label:
     case Intrinsic::invariant_start:
     case Intrinsic::invariant_end:
     case Intrinsic::lifetime_start:

llvm/include/llvm/Bitcode/LLVMBitCodes.h

@@ -310,6 +310,7 @@ enum MetadataCodes {
   METADATA_GLOBAL_VAR_EXPR = 37,        // [distinct, var, expr]
   METADATA_INDEX_OFFSET = 38,           // [offset]
   METADATA_INDEX = 39,                  // [bitpos]
+  METADATA_LABEL = 40,                  // [distinct, scope, name, file, line]
 };
 
 // The constants block (CONSTANTS_BLOCK_ID) describes emission for each

llvm/include/llvm/IR/DIBuilder.h

@@ -46,6 +46,7 @@ namespace llvm {
     DICompileUnit *CUNode;   ///< The one compile unit created by this DIBuiler.
     Function *DeclareFn;     ///< llvm.dbg.declare
     Function *ValueFn;       ///< llvm.dbg.value
+    Function *LabelFn;       ///< llvm.dbg.label
 
     SmallVector<Metadata *, 4> AllEnumTypes;
     /// Track the RetainTypes, since they can be updated later on.
@@ -69,6 +70,9 @@ namespace llvm {
     /// copy.
     DenseMap<MDNode *, SmallVector<TrackingMDNodeRef, 1>> PreservedVariables;
 
+    /// Each subprogram's preserved labels.
+    DenseMap<MDNode *, SmallVector<TrackingMDNodeRef, 1>> PreservedLabels;
+
     /// Create a temporary.
     ///
     /// Create an \a temporary node and track it in \a UnresolvedNodes.
@@ -79,6 +83,10 @@ namespace llvm {
                                DIExpression *Expr, const DILocation *DL,
                                BasicBlock *InsertBB, Instruction *InsertBefore);
 
+    /// Internal helper for insertLabel.
+    Instruction *insertLabel(DILabel *LabelInfo, const DILocation *DL,
+                             BasicBlock *InsertBB, Instruction *InsertBefore);
+
     /// Internal helper for insertDbgValueIntrinsic.
     Instruction *
     insertDbgValueIntrinsic(llvm::Value *Val, DILocalVariable *VarInfo,
@@ -591,6 +599,14 @@ namespace llvm {
                        DINode::DIFlags Flags = DINode::FlagZero,
                        uint32_t AlignInBits = 0);
 
+    /// Create a new descriptor for an label.
+    ///
+    /// \c Scope must be a \a DILocalScope, and thus its scope chain eventually
+    /// leads to a \a DISubprogram.
+    DILabel *
+    createLabel(DIScope *Scope, StringRef Name, DIFile *File, unsigned LineNo,
+                bool AlwaysPreserve = false);
+
     /// Create a new descriptor for a parameter variable.
     ///
     /// \c Scope must be a \a DILocalScope, and thus its scope chain eventually
@@ -782,6 +798,20 @@ namespace llvm {
                                DIExpression *Expr, const DILocation *DL,
                                Instruction *InsertBefore);
 
+    /// Insert a new llvm.dbg.label intrinsic call.
+    /// \param LabelInfo    Label's debug info descriptor.
+    /// \param DL           Debug info location.
+    /// \param InsertBefore Location for the new intrinsic.
+    Instruction *insertLabel(DILabel *LabelInfo, const DILocation *DL,
+                             Instruction *InsertBefore);
+
+    /// Insert a new llvm.dbg.label intrinsic call.
+    /// \param LabelInfo    Label's debug info descriptor.
+    /// \param DL           Debug info location.
+    /// \param InsertAtEnd Location for the new intrinsic.
+    Instruction *insertLabel(DILabel *LabelInfo, const DILocation *DL,
+                             BasicBlock *InsertAtEnd);
+
     /// Insert a new llvm.dbg.value intrinsic call.
     /// \param Val          llvm::Value of the variable
     /// \param VarInfo      Variable's debug info descriptor.

llvm/include/llvm/IR/DebugInfoMetadata.h

@@ -232,6 +232,7 @@ class DINode : public MDNode {
     case DITemplateValueParameterKind:
     case DIGlobalVariableKind:
     case DILocalVariableKind:
+    case DILabelKind:
     case DIObjCPropertyKind:
     case DIImportedEntityKind:
     case DIModuleKind:
@@ -1609,13 +1610,13 @@ class DISubprogram : public DILocalScope {
           unsigned VirtualIndex, int ThisAdjustment, DIFlags Flags,
           bool IsOptimized, DICompileUnit *Unit,
           DITemplateParameterArray TemplateParams, DISubprogram *Declaration,
-          DILocalVariableArray Variables, DITypeArray ThrownTypes,
+          DINodeArray RetainedNodes, DITypeArray ThrownTypes,
           StorageType Storage, bool ShouldCreate = true) {
     return getImpl(Context, Scope, getCanonicalMDString(Context, Name),
                    getCanonicalMDString(Context, LinkageName), File, Line, Type,
                    IsLocalToUnit, IsDefinition, ScopeLine, ContainingType,
                    Virtuality, VirtualIndex, ThisAdjustment, Flags, IsOptimized,
-                   Unit, TemplateParams.get(), Declaration, Variables.get(),
+                   Unit, TemplateParams.get(), Declaration, RetainedNodes.get(),
                    ThrownTypes.get(), Storage, ShouldCreate);
   }
   static DISubprogram *
@@ -1624,7 +1625,7 @@ class DISubprogram : public DILocalScope {
           bool IsLocalToUnit, bool IsDefinition, unsigned ScopeLine,
           Metadata *ContainingType, unsigned Virtuality, unsigned VirtualIndex,
           int ThisAdjustment, DIFlags Flags, bool IsOptimized, Metadata *Unit,
-          Metadata *TemplateParams, Metadata *Declaration, Metadata *Variables,
+          Metadata *TemplateParams, Metadata *Declaration, Metadata *RetainedNodes,
           Metadata *ThrownTypes, StorageType Storage, bool ShouldCreate = true);
 
   TempDISubprogram cloneImpl() const {
@@ -1633,7 +1634,7 @@ class DISubprogram : public DILocalScope {
                         isDefinition(), getScopeLine(), getContainingType(),
                         getVirtuality(), getVirtualIndex(), getThisAdjustment(),
                         getFlags(), isOptimized(), getUnit(),
-                        getTemplateParams(), getDeclaration(), getVariables(),
+                        getTemplateParams(), getDeclaration(), getRetainedNodes(),
                         getThrownTypes());
   }
 
@@ -1647,24 +1648,24 @@ class DISubprogram : public DILocalScope {
                      bool IsOptimized, DICompileUnit *Unit,
                      DITemplateParameterArray TemplateParams = nullptr,
                      DISubprogram *Declaration = nullptr,
-                     DILocalVariableArray Variables = nullptr,
+                     DINodeArray RetainedNodes = nullptr,
                      DITypeArray ThrownTypes = nullptr),
                     (Scope, Name, LinkageName, File, Line, Type, IsLocalToUnit,
                      IsDefinition, ScopeLine, ContainingType, Virtuality,
                      VirtualIndex, ThisAdjustment, Flags, IsOptimized, Unit,
-                     TemplateParams, Declaration, Variables, ThrownTypes))
+                     TemplateParams, Declaration, RetainedNodes, ThrownTypes))
   DEFINE_MDNODE_GET(
       DISubprogram,
       (Metadata * Scope, MDString *Name, MDString *LinkageName, Metadata *File,
        unsigned Line, Metadata *Type, bool IsLocalToUnit, bool IsDefinition,
        unsigned ScopeLine, Metadata *ContainingType, unsigned Virtuality,
        unsigned VirtualIndex, int ThisAdjustment, DIFlags Flags,
        bool IsOptimized, Metadata *Unit, Metadata *TemplateParams = nullptr,
-       Metadata *Declaration = nullptr, Metadata *Variables = nullptr,
+       Metadata *Declaration = nullptr, Metadata *RetainedNodes = nullptr,
        Metadata *ThrownTypes = nullptr),
       (Scope, Name, LinkageName, File, Line, Type, IsLocalToUnit, IsDefinition,
        ScopeLine, ContainingType, Virtuality, VirtualIndex, ThisAdjustment,
-       Flags, IsOptimized, Unit, TemplateParams, Declaration, Variables,
+       Flags, IsOptimized, Unit, TemplateParams, Declaration, RetainedNodes,
        ThrownTypes))
 
   TempDISubprogram clone() const { return cloneImpl(); }
@@ -1738,8 +1739,8 @@ class DISubprogram : public DILocalScope {
   DISubprogram *getDeclaration() const {
     return cast_or_null<DISubprogram>(getRawDeclaration());
   }
-  DILocalVariableArray getVariables() const {
-    return cast_or_null<MDTuple>(getRawVariables());
+  DINodeArray getRetainedNodes() const {
+    return cast_or_null<MDTuple>(getRawRetainedNodes());
   }
   DITypeArray getThrownTypes() const {
     return cast_or_null<MDTuple>(getRawThrownTypes());
@@ -1751,7 +1752,7 @@ class DISubprogram : public DILocalScope {
   Metadata *getRawType() const { return getOperand(4); }
   Metadata *getRawUnit() const { return getOperand(5); }
   Metadata *getRawDeclaration() const { return getOperand(6); }
-  Metadata *getRawVariables() const { return getOperand(7); }
+  Metadata *getRawRetainedNodes() const { return getOperand(7); }
   Metadata *getRawContainingType() const {
     return getNumOperands() > 8 ? getOperandAs<Metadata>(8) : nullptr;
   }
@@ -2607,6 +2608,76 @@ class DILocalVariable : public DIVariable {
   }
 };
 
+/// Label.
+///
+class DILabel : public DINode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  unsigned Line;
+
+  DILabel(LLVMContext &C, StorageType Storage, unsigned Line,
+          ArrayRef<Metadata *> Ops)
+      : DINode(C, DILabelKind, Storage, dwarf::DW_TAG_label, Ops), Line(Line) {}
+  ~DILabel() = default;
+
+  static DILabel *getImpl(LLVMContext &Context, DIScope *Scope,
+                          StringRef Name, DIFile *File, unsigned Line,
+                          StorageType Storage,
+                          bool ShouldCreate = true) {
+    return getImpl(Context, Scope, getCanonicalMDString(Context, Name), File,
+                   Line, Storage, ShouldCreate);
+  }
+  static DILabel *getImpl(LLVMContext &Context, Metadata *Scope,
+                          MDString *Name, Metadata *File, unsigned Line,
+                          StorageType Storage,
+                          bool ShouldCreate = true);
+
+  TempDILabel cloneImpl() const {
+    return getTemporary(getContext(), getScope(), getName(), getFile(),
+                        getLine());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DILabel,
+                    (DILocalScope * Scope, StringRef Name, DIFile *File,
+                     unsigned Line),
+                    (Scope, Name, File, Line))
+  DEFINE_MDNODE_GET(DILabel,
+                    (Metadata * Scope, MDString *Name, Metadata *File,
+                     unsigned Line),
+                    (Scope, Name, File, Line))
+
+  TempDILabel clone() const { return cloneImpl(); }
+
+  /// Get the local scope for this label.
+  ///
+  /// Labels must be defined in a local scope.
+  DILocalScope *getScope() const {
+    return cast_or_null<DILocalScope>(getRawScope());
+  }
+  unsigned getLine() const { return Line; }
+  StringRef getName() const { return getStringOperand(1); }
+  DIFile *getFile() const { return cast_or_null<DIFile>(getRawFile()); }
+
+  Metadata *getRawScope() const { return getOperand(0); }
+  MDString *getRawName() const { return getOperandAs<MDString>(1); }
+  Metadata *getRawFile() const { return getOperand(2); }
+
+  /// Check that a location is valid for this label.
+  ///
+  /// Check that \c DL exists, is in the same subprogram, and has the same
+  /// inlined-at location as \c this.  (Otherwise, it's not a valid attachment
+  /// to a \a DbgInfoIntrinsic.)
+  bool isValidLocationForIntrinsic(const DILocation *DL) const {
+    return DL && getScope()->getSubprogram() == DL->getScope()->getSubprogram();
+  }
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DILabelKind;
+  }
+};
+
 class DIObjCProperty : public DINode {
   friend class LLVMContextImpl;
   friend class MDNode;

llvm/include/llvm/IR/InstVisitor.h

@@ -213,6 +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 visitDbgInfoIntrinsic(DbgInfoIntrinsic &I) { DELEGATE(IntrinsicInst); }
   RetTy visitMemSetInst(MemSetInst &I)            { DELEGATE(MemIntrinsic); }
   RetTy visitMemCpyInst(MemCpyInst &I)            { DELEGATE(MemTransferInst); }
@@ -272,6 +273,7 @@ class InstVisitor {
       default:                     DELEGATE(IntrinsicInst);
       case Intrinsic::dbg_declare: DELEGATE(DbgDeclareInst);
       case Intrinsic::dbg_value:   DELEGATE(DbgValueInst);
+      case Intrinsic::dbg_label:   DELEGATE(DbgLabelInst);
       case Intrinsic::memcpy:      DELEGATE(MemCpyInst);
       case Intrinsic::memmove:     DELEGATE(MemMoveInst);
       case Intrinsic::memset:      DELEGATE(MemSetInst);

llvm/include/llvm/IR/IntrinsicInst.h

@@ -100,6 +100,7 @@ namespace llvm {
       case Intrinsic::dbg_declare:
       case Intrinsic::dbg_value:
       case Intrinsic::dbg_addr:
+      case Intrinsic::dbg_label:
         return true;
       default: return false;
       }
@@ -159,6 +160,32 @@ namespace llvm {
     /// @}
   };
 
+  /// This represents the llvm.dbg.label instruction.
+  class DbgLabelInst : public DbgInfoIntrinsic {
+  public:
+    DILabel *getLabel() const {
+      return cast<DILabel>(getRawVariable());
+    }
+
+    Metadata *getRawVariable() const {
+      return cast<MetadataAsValue>(getArgOperand(0))->getMetadata();
+    }
+
+    Metadata *getRawExpression() const {
+      return nullptr;
+    }
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    /// @{
+    static bool classof(const IntrinsicInst *I) {
+      return I->getIntrinsicID() == Intrinsic::dbg_label;
+    }
+    static bool classof(const Value *V) {
+      return isa<IntrinsicInst>(V) && classof(cast<IntrinsicInst>(V));
+    }
+    /// @}
+  };
+
   /// This is the common base class for constrained floating point intrinsics.
   class ConstrainedFPIntrinsic : public IntrinsicInst {
   public:

llvm/include/llvm/IR/Intrinsics.td

@@ -599,6 +599,8 @@ let IntrProperties = [IntrNoMem, IntrSpeculatable] in {
                                        [llvm_metadata_ty,
                                         llvm_metadata_ty,
                                         llvm_metadata_ty]>;
+  def int_dbg_label        : Intrinsic<[],
+                                       [llvm_metadata_ty]>;
 }
 
 //===------------------ Exception Handling Intrinsics----------------------===//

llvm/include/llvm/IR/Metadata.def

@@ -108,6 +108,7 @@ HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DITemplateValueParameter)
 HANDLE_SPECIALIZED_MDNODE_BRANCH(DIVariable)
 HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DIGlobalVariable)
 HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DILocalVariable)
+HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DILabel)
 HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DIObjCProperty)
 HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DIImportedEntity)
 HANDLE_SPECIALIZED_MDNODE_BRANCH(DIMacroNode)

llvm/lib/Analysis/ObjCARCInstKind.cpp

@@ -209,6 +209,7 @@ static bool isInertIntrinsic(unsigned ID) {
   // Don't let dbg info affect our results.
   case Intrinsic::dbg_declare:
   case Intrinsic::dbg_value:
+  case Intrinsic::dbg_label:
     // Short cut: Some intrinsics obviously don't use ObjC pointers.
     return true;
   default:

llvm/lib/Analysis/ValueTracking.cpp

@@ -501,6 +501,7 @@ bool llvm::isAssumeLikeIntrinsic(const Instruction *I) {
       case Intrinsic::sideeffect:
       case Intrinsic::dbg_declare:
       case Intrinsic::dbg_value:
+      case Intrinsic::dbg_label:
       case Intrinsic::invariant_start:
       case Intrinsic::invariant_end:
       case Intrinsic::lifetime_start: