[DebugInfo] Prepare DIBuilder for labels.

[HsiangKai]

Summary

Implement createLabel() to allocate DILabel objects.
Implement insertLabel() to insert llvm.dbg.label intrinsic function in LLVM IR.

Clang could use DIBuilder::createLabel() to allocate DILabel, then pass the object
to DIBuilder::insertLabel() to insert llvm.dbg.label intrinsic function in LLVM IR.

include/llvm/IR/DIBuilder.h

namespace llvm {
 
   class DIBuilder {
     Module &M;
     LLVMContext &VMContext;
 
     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.
     SmallVector<TrackingMDNodeRef, 4> AllRetainTypes;
     SmallVector<Metadata *, 4> AllSubprograms;
     SmallVector<Metadata *, 4> AllGVs;
     SmallVector<TrackingMDNodeRef, 4> AllImportedModules;
     /// Map Macro parent (which can be DIMacroFile or nullptr) to a list of
class DIBuilder {
     /// Create an \a temporary node and track it in \a UnresolvedNodes.
     void trackIfUnresolved(MDNode *N);
 
     /// Internal helper for insertDeclare.
     Instruction *insertDeclare(llvm::Value *Storage, DILocalVariable *VarInfo,
                                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,
                             DIExpression *Expr, const DILocation *DL,
                             BasicBlock *InsertBB, Instruction *InsertBefore);
 
   public:
     /// Construct a builder for a module.
public:
     /// If \c AlwaysPreserve, this variable will be referenced from its
     /// containing subprogram, and will survive some optimizations.
     DILocalVariable *
     createAutoVariable(DIScope *Scope, StringRef Name, DIFile *File,
                        unsigned LineNo, DIType *Ty, bool AlwaysPreserve = false,
                        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);
+
     /// Create a new descriptor for a parameter variable.
     ///
     /// \c Scope must be a \a DILocalScope, and thus its scope chain eventually
     /// leads to a \a DISubprogram.
     ///
     /// \c ArgNo is the index (starting from \c 1) of this variable in the
     /// subprogram parameters.  \c ArgNo should not conflict with other
     /// parameters of the same subprogram.
public:
     /// \param VarInfo      Variable's debug info descriptor.
     /// \param Expr         A complex location expression.
     /// \param DL           Debug info location.
     /// \param InsertBefore Location for the new intrinsic.
     Instruction *insertDeclare(llvm::Value *Storage, DILocalVariable *VarInfo,
                                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.
     /// \param Expr         A complex location expression.
     /// \param DL           Debug info location.
     /// \param InsertAtEnd Location for the new intrinsic.
     Instruction *insertDbgValueIntrinsic(llvm::Value *Val,
                                          DILocalVariable *VarInfo,

lib/IR/DIBuilder.cpp

 
 cl::opt<bool>
     UseDbgAddr("use-dbg-addr",
                llvm::cl::desc("Use llvm.dbg.addr for all local variables"),
                cl::init(false), cl::Hidden);
 
 DIBuilder::DIBuilder(Module &m, bool AllowUnresolvedNodes, DICompileUnit *CU)
   : M(m), VMContext(M.getContext()), CUNode(CU),
-      DeclareFn(nullptr), ValueFn(nullptr),
+      DeclareFn(nullptr), ValueFn(nullptr), LabelFn(nullptr),
       AllowUnresolvedNodes(AllowUnresolvedNodes) {}
 
 void DIBuilder::trackIfUnresolved(MDNode *N) {
   if (!N)
     return;
   if (N->isResolved())
     return;
 
DILocalVariable *DIBuilder::createParameterVariable(
     DIScope *Scope, StringRef Name, unsigned ArgNo, DIFile *File,
     unsigned LineNo, DIType *Ty, bool AlwaysPreserve, DINode::DIFlags Flags) {
   assert(ArgNo && "Expected non-zero argument number for parameter");
   return createLocalVariable(VMContext, PreservedVariables, Scope, Name, ArgNo,
                              File, LineNo, Ty, AlwaysPreserve, Flags,
                              /* AlignInBits */0);
 }
 
+DILabel *DIBuilder::createLabel(DIScope *Scope, StringRef Name, DIFile *File,
+                                unsigned LineNo) {
+  DIScope *Context = getNonCompileUnitScope(Scope);
+
+  auto *Node =
+      DILabel::get(VMContext, cast_or_null<DILocalScope>(Context), Name,
+                   File, LineNo);
+  return Node;
+}
+
 DIExpression *DIBuilder::createExpression(ArrayRef<uint64_t> Addr) {
   return DIExpression::get(VMContext, Addr);
 }
 
 DIExpression *DIBuilder::createExpression(ArrayRef<int64_t> Signed) {
   // TODO: Remove the callers of this signed version and delete.
   SmallVector<uint64_t, 8> Addr(Signed.begin(), Signed.end());
   return createExpression(Addr);
Instruction *DIBuilder::insertDeclare(Value *Storage, DILocalVariable *VarInfo,
                                       DIExpression *Expr, const DILocation *DL,
                                       BasicBlock *InsertAtEnd) {
   // If this block already has a terminator then insert this intrinsic before
   // the terminator. Otherwise, put it at the end of the block.
   Instruction *InsertBefore = InsertAtEnd->getTerminator();
   return insertDeclare(Storage, VarInfo, Expr, DL, InsertAtEnd, InsertBefore);
 }
 
+Instruction *DIBuilder::insertLabel(DILabel *LabelInfo, const DILocation *DL,
+                                    Instruction *InsertBefore) {
+  return insertLabel(
+      LabelInfo, DL, InsertBefore ? InsertBefore->getParent() : nullptr,
+      InsertBefore);
+}
+
+Instruction *DIBuilder::insertLabel(DILabel *LabelInfo, const DILocation *DL,
+                                    BasicBlock *InsertAtEnd) {
+  return insertLabel(LabelInfo, DL, InsertAtEnd, nullptr);
+}
+
 Instruction *DIBuilder::insertDbgValueIntrinsic(Value *V,
                                                 DILocalVariable *VarInfo,
                                                 DIExpression *Expr,
                                                 const DILocation *DL,
                                                 Instruction *InsertBefore) {
   return insertDbgValueIntrinsic(
       V, VarInfo, Expr, DL, InsertBefore ? InsertBefore->getParent() : nullptr,
       InsertBefore);
Instruction *DIBuilder::insertDbgValueIntrinsic(
   Value *Args[] = {getDbgIntrinsicValueImpl(VMContext, V),
                    MetadataAsValue::get(VMContext, VarInfo),
                    MetadataAsValue::get(VMContext, Expr)};
 
   IRBuilder<> B = getIRBForDbgInsertion(DL, InsertBB, InsertBefore);
   return B.CreateCall(ValueFn, Args);
 }
 
+Instruction *DIBuilder::insertLabel(
+    DILabel *LabelInfo, const DILocation *DL,
+    BasicBlock *InsertBB, Instruction *InsertBefore) {
+  assert(LabelInfo && "empty or invalid DILabel* passed to dbg.label");
+  assert(DL && "Expected debug loc");
+  assert(DL->getScope()->getSubprogram() ==
+             LabelInfo->getScope()->getSubprogram() &&
+         "Expected matching subprograms");
+  if (!LabelFn)
+    LabelFn = Intrinsic::getDeclaration(&M, Intrinsic::dbg_label);
+
+  trackIfUnresolved(LabelInfo);
+  Value *Args[] = {MetadataAsValue::get(VMContext, LabelInfo)};
+
+  IRBuilder<> B = getIRBForDbgInsertion(DL, InsertBB, InsertBefore);
+  return B.CreateCall(LabelFn, Args);
+}
+
 void DIBuilder::replaceVTableHolder(DICompositeType *&T,
                                     DIType *VTableHolder) {
   {
     TypedTrackingMDRef<DICompositeType> N(T);
     N->replaceVTableHolder(VTableHolder);
     T = N.get();
   }