[DebugInfo] Support for DW_TAG_generic_subrange

This is needed to support fortran assumed rank arrays which
have runtime rank.

  Summary:
Fortran assumed rank arrays have dynamic rank. DWARF TAG
DW_TAG_generic_subrange is needed to support that.

  Testing:
unit test cases added (hand-written)
check llvm
check debug-info

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D89218

Author: alokkrsharma

llvm/include/llvm-c/DebugInfo.h

@@ -160,7 +160,8 @@ enum {
   LLVMDIMacroMetadataKind,
   LLVMDIMacroFileMetadataKind,
   LLVMDICommonBlockMetadataKind,
-  LLVMDIStringTypeMetadataKind
+  LLVMDIStringTypeMetadataKind,
+  LLVMDIGenericSubrangeMetadataKind
 };
 typedef unsigned LLVMMetadataKind;
 

llvm/include/llvm/Bitcode/LLVMBitCodes.h

@@ -341,7 +341,8 @@ enum MetadataCodes {
   METADATA_STRING_TYPE = 41,            // [distinct, name, size, align,...]
   // Codes 42 and 43 are reserved for support for Fortran array specific debug
   // info.
-  METADATA_COMMON_BLOCK = 44 // [distinct, scope, name, variable,...]
+  METADATA_COMMON_BLOCK = 44,    // [distinct, scope, name, variable,...]
+  METADATA_GENERIC_SUBRANGE = 45 // [distinct, count, lo, up, stride]
 };
 
 // The constants block (CONSTANTS_BLOCK_ID) describes emission for each

llvm/include/llvm/IR/DIBuilder.h

@@ -582,6 +582,12 @@ namespace llvm {
     DISubrange *getOrCreateSubrange(Metadata *Count, Metadata *LowerBound,
                                     Metadata *UpperBound, Metadata *Stride);
 
+    DIGenericSubrange *
+    getOrCreateGenericSubrange(DIGenericSubrange::BoundType Count,
+                               DIGenericSubrange::BoundType LowerBound,
+                               DIGenericSubrange::BoundType UpperBound,
+                               DIGenericSubrange::BoundType Stride);
+
     /// Create a new descriptor for the specified variable.
     /// \param Context     Variable scope.
     /// \param Name        Name of the variable.

llvm/include/llvm/IR/DebugInfoMetadata.h

@@ -201,6 +201,7 @@ class DINode : public MDNode {
     case DIObjCPropertyKind:
     case DIImportedEntityKind:
     case DIModuleKind:
+    case DIGenericSubrangeKind:
       return true;
     }
   }
@@ -351,6 +352,52 @@ class DISubrange : public DINode {
   }
 };
 
+class DIGenericSubrange : public DINode {
+  friend class LLVMContextImpl;
+  friend class MDNode;
+
+  DIGenericSubrange(LLVMContext &C, StorageType Storage,
+                    ArrayRef<Metadata *> Ops)
+      : DINode(C, DIGenericSubrangeKind, Storage,
+               dwarf::DW_TAG_generic_subrange, Ops) {}
+
+  ~DIGenericSubrange() = default;
+
+  static DIGenericSubrange *getImpl(LLVMContext &Context, Metadata *CountNode,
+                                    Metadata *LowerBound, Metadata *UpperBound,
+                                    Metadata *Stride, StorageType Storage,
+                                    bool ShouldCreate = true);
+
+  TempDIGenericSubrange cloneImpl() const {
+    return getTemporary(getContext(), getRawCountNode(), getRawLowerBound(),
+                        getRawUpperBound(), getRawStride());
+  }
+
+public:
+  DEFINE_MDNODE_GET(DIGenericSubrange,
+                    (Metadata * CountNode, Metadata *LowerBound,
+                     Metadata *UpperBound, Metadata *Stride),
+                    (CountNode, LowerBound, UpperBound, Stride))
+
+  TempDIGenericSubrange clone() const { return cloneImpl(); }
+
+  Metadata *getRawCountNode() const { return getOperand(0).get(); }
+  Metadata *getRawLowerBound() const { return getOperand(1).get(); }
+  Metadata *getRawUpperBound() const { return getOperand(2).get(); }
+  Metadata *getRawStride() const { return getOperand(3).get(); }
+
+  using BoundType = PointerUnion<DIVariable *, DIExpression *>;
+
+  BoundType getCount() const;
+  BoundType getLowerBound() const;
+  BoundType getUpperBound() const;
+  BoundType getStride() const;
+
+  static bool classof(const Metadata *MD) {
+    return MD->getMetadataID() == DIGenericSubrangeKind;
+  }
+};
+
 /// Enumeration value.
 ///
 /// TODO: Add a pointer to the context (DW_TAG_enumeration_type) once that no
@@ -2524,6 +2571,9 @@ class DIExpression : public MDNode {
   /// Determine whether this represents a standalone constant value.
   bool isConstant() const;
 
+  /// Determine whether this represents a standalone signed constant value.
+  bool isSignedConstant() const;
+
   using element_iterator = ArrayRef<uint64_t>::iterator;
 
   element_iterator elements_begin() const { return getElements().begin(); }

llvm/include/llvm/IR/Metadata.def

@@ -115,6 +115,7 @@ HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DIMacro)
 HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DIMacroFile)
 HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DICommonBlock)
 HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DIStringType)
+HANDLE_SPECIALIZED_MDNODE_LEAF_UNIQUABLE(DIGenericSubrange)
 
 #undef HANDLE_METADATA
 #undef HANDLE_METADATA_LEAF

llvm/lib/AsmParser/LLParser.cpp

@@ -4670,6 +4670,39 @@ bool LLParser::parseDISubrange(MDNode *&Result, bool IsDistinct) {
   return false;
 }
 
+/// parseDIGenericSubrange:
+///   ::= !DIGenericSubrange(lowerBound: !node1, upperBound: !node2, stride:
+///   !node3)
+bool LLParser::parseDIGenericSubrange(MDNode *&Result, bool IsDistinct) {
+#define VISIT_MD_FIELDS(OPTIONAL, REQUIRED)                                    \
+  OPTIONAL(count, MDSignedOrMDField, );                                        \
+  OPTIONAL(lowerBound, MDSignedOrMDField, );                                   \
+  OPTIONAL(upperBound, MDSignedOrMDField, );                                   \
+  OPTIONAL(stride, MDSignedOrMDField, );
+  PARSE_MD_FIELDS();
+#undef VISIT_MD_FIELDS
+
+  auto ConvToMetadata = [&](MDSignedOrMDField Bound) -> Metadata * {
+    if (Bound.isMDSignedField())
+      return DIExpression::get(
+          Context, {dwarf::DW_OP_consts,
+                    static_cast<uint64_t>(Bound.getMDSignedValue())});
+    if (Bound.isMDField())
+      return Bound.getMDFieldValue();
+    return nullptr;
+  };
+
+  Metadata *Count = ConvToMetadata(count);
+  Metadata *LowerBound = ConvToMetadata(lowerBound);
+  Metadata *UpperBound = ConvToMetadata(upperBound);
+  Metadata *Stride = ConvToMetadata(stride);
+
+  Result = GET_OR_DISTINCT(DIGenericSubrange,
+                           (Context, Count, LowerBound, UpperBound, Stride));
+
+  return false;
+}
+
 /// parseDIEnumerator:
 ///   ::= !DIEnumerator(value: 30, isUnsigned: true, name: "SomeKind")
 bool LLParser::parseDIEnumerator(MDNode *&Result, bool IsDistinct) {

llvm/lib/Bitcode/Reader/MetadataLoader.cpp

@@ -875,6 +875,7 @@ MetadataLoader::MetadataLoaderImpl::lazyLoadModuleMetadataBlock() {
       case bitc::METADATA_OBJC_PROPERTY:
       case bitc::METADATA_IMPORTED_ENTITY:
       case bitc::METADATA_GLOBAL_VAR_EXPR:
+      case bitc::METADATA_GENERIC_SUBRANGE:
         // We don't expect to see any of these, if we see one, give up on
         // lazy-loading and fallback.
         MDStringRef.clear();
@@ -1371,6 +1372,18 @@ Error MetadataLoader::MetadataLoaderImpl::parseOneMetadata(
     NextMetadataNo++;
     break;
   }
+  case bitc::METADATA_GENERIC_SUBRANGE: {
+    Metadata *Val = nullptr;
+    Val = GET_OR_DISTINCT(DIGenericSubrange,
+                          (Context, getMDOrNull(Record[1]),
+                           getMDOrNull(Record[2]), getMDOrNull(Record[3]),
+                           getMDOrNull(Record[4])));
+
+    MetadataList.assignValue(Val, NextMetadataNo);
+    IsDistinct = Record[0] & 1;
+    NextMetadataNo++;
+    break;
+  }
   case bitc::METADATA_ENUMERATOR: {
     if (Record.size() < 3)
       return error("Invalid record");

llvm/lib/Bitcode/Writer/BitcodeWriter.cpp

@@ -300,6 +300,9 @@ class ModuleBitcodeWriter : public ModuleBitcodeWriterBase {
                           SmallVectorImpl<uint64_t> &Record, unsigned &Abbrev);
   void writeDISubrange(const DISubrange *N, SmallVectorImpl<uint64_t> &Record,
                        unsigned Abbrev);
+  void writeDIGenericSubrange(const DIGenericSubrange *N,
+                              SmallVectorImpl<uint64_t> &Record,
+                              unsigned Abbrev);
   void writeDIEnumerator(const DIEnumerator *N,
                          SmallVectorImpl<uint64_t> &Record, unsigned Abbrev);
   void writeDIBasicType(const DIBasicType *N, SmallVectorImpl<uint64_t> &Record,
@@ -1553,6 +1556,19 @@ void ModuleBitcodeWriter::writeDISubrange(const DISubrange *N,
   Record.clear();
 }
 
+void ModuleBitcodeWriter::writeDIGenericSubrange(
+    const DIGenericSubrange *N, SmallVectorImpl<uint64_t> &Record,
+    unsigned Abbrev) {
+  Record.push_back((uint64_t)N->isDistinct());
+  Record.push_back(VE.getMetadataOrNullID(N->getRawCountNode()));
+  Record.push_back(VE.getMetadataOrNullID(N->getRawLowerBound()));
+  Record.push_back(VE.getMetadataOrNullID(N->getRawUpperBound()));
+  Record.push_back(VE.getMetadataOrNullID(N->getRawStride()));
+
+  Stream.EmitRecord(bitc::METADATA_GENERIC_SUBRANGE, Record, Abbrev);
+  Record.clear();
+}
+
 static void emitSignedInt64(SmallVectorImpl<uint64_t> &Vals, uint64_t V) {
   if ((int64_t)V >= 0)
     Vals.push_back(V << 1);

llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -812,6 +812,19 @@ static SmallVector<const DIVariable *, 2> dependencies(DbgVariable *Var) {
       if (auto ST = Subrange->getStride())
         if (auto *Dependency = ST.dyn_cast<DIVariable *>())
           Result.push_back(Dependency);
+    } else if (auto *GenericSubrange = dyn_cast<DIGenericSubrange>(El)) {
+      if (auto Count = GenericSubrange->getCount())
+        if (auto *Dependency = Count.dyn_cast<DIVariable *>())
+          Result.push_back(Dependency);
+      if (auto LB = GenericSubrange->getLowerBound())
+        if (auto *Dependency = LB.dyn_cast<DIVariable *>())
+          Result.push_back(Dependency);
+      if (auto UB = GenericSubrange->getUpperBound())
+        if (auto *Dependency = UB.dyn_cast<DIVariable *>())
+          Result.push_back(Dependency);
+      if (auto ST = GenericSubrange->getStride())
+        if (auto *Dependency = ST.dyn_cast<DIVariable *>())
+          Result.push_back(Dependency);
     }
   }
   return Result;

llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp

@@ -541,6 +541,10 @@ void DwarfExpression::addExpression(DIExpressionCursor &&ExprCursor,
       assert(!isRegisterLocation());
       emitConstu(Op->getArg(0));
       break;
+    case dwarf::DW_OP_consts:
+      assert(!isRegisterLocation());
+      emitSigned(Op->getArg(0));
+      break;
     case dwarf::DW_OP_LLVM_convert: {
       unsigned BitSize = Op->getArg(0);
       dwarf::TypeKind Encoding = static_cast<dwarf::TypeKind>(Op->getArg(1));

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -1357,7 +1357,7 @@ void DwarfUnit::constructSubrangeDIE(DIE &Buffer, const DISubrange *SR,
   if (auto *CI = SR->getCount().dyn_cast<ConstantInt*>())
     Count = CI->getSExtValue();
 
-  auto addBoundTypeEntry = [&](dwarf::Attribute Attr,
+  auto AddBoundTypeEntry = [&](dwarf::Attribute Attr,
                                DISubrange::BoundType Bound) -> void {
     if (auto *BV = Bound.dyn_cast<DIVariable *>()) {
       if (auto *VarDIE = getDIE(BV))
@@ -1375,17 +1375,53 @@ void DwarfUnit::constructSubrangeDIE(DIE &Buffer, const DISubrange *SR,
     }
   };
 
-  addBoundTypeEntry(dwarf::DW_AT_lower_bound, SR->getLowerBound());
+  AddBoundTypeEntry(dwarf::DW_AT_lower_bound, SR->getLowerBound());
 
   if (auto *CV = SR->getCount().dyn_cast<DIVariable*>()) {
     if (auto *CountVarDIE = getDIE(CV))
       addDIEEntry(DW_Subrange, dwarf::DW_AT_count, *CountVarDIE);
   } else if (Count != -1)
     addUInt(DW_Subrange, dwarf::DW_AT_count, None, Count);
 
-  addBoundTypeEntry(dwarf::DW_AT_upper_bound, SR->getUpperBound());
+  AddBoundTypeEntry(dwarf::DW_AT_upper_bound, SR->getUpperBound());
 
-  addBoundTypeEntry(dwarf::DW_AT_byte_stride, SR->getStride());
+  AddBoundTypeEntry(dwarf::DW_AT_byte_stride, SR->getStride());
+}
+
+void DwarfUnit::constructGenericSubrangeDIE(DIE &Buffer,
+                                            const DIGenericSubrange *GSR,
+                                            DIE *IndexTy) {
+  DIE &DwGenericSubrange =
+      createAndAddDIE(dwarf::DW_TAG_generic_subrange, Buffer);
+  addDIEEntry(DwGenericSubrange, dwarf::DW_AT_type, *IndexTy);
+
+  int64_t DefaultLowerBound = getDefaultLowerBound();
+
+  auto AddBoundTypeEntry = [&](dwarf::Attribute Attr,
+                               DIGenericSubrange::BoundType Bound) -> void {
+    if (auto *BV = Bound.dyn_cast<DIVariable *>()) {
+      if (auto *VarDIE = getDIE(BV))
+        addDIEEntry(DwGenericSubrange, Attr, *VarDIE);
+    } else if (auto *BE = Bound.dyn_cast<DIExpression *>()) {
+      if (BE->isSignedConstant()) {
+        if (Attr != dwarf::DW_AT_lower_bound || DefaultLowerBound == -1 ||
+            static_cast<int64_t>(BE->getElement(1)) != DefaultLowerBound)
+          addSInt(DwGenericSubrange, Attr, dwarf::DW_FORM_sdata,
+                  BE->getElement(1));
+      } else {
+        DIELoc *Loc = new (DIEValueAllocator) DIELoc;
+        DIEDwarfExpression DwarfExpr(*Asm, getCU(), *Loc);
+        DwarfExpr.setMemoryLocationKind();
+        DwarfExpr.addExpression(BE);
+        addBlock(DwGenericSubrange, Attr, DwarfExpr.finalize());
+      }
+    }
+  };
+
+  AddBoundTypeEntry(dwarf::DW_AT_lower_bound, GSR->getLowerBound());
+  AddBoundTypeEntry(dwarf::DW_AT_count, GSR->getCount());
+  AddBoundTypeEntry(dwarf::DW_AT_upper_bound, GSR->getUpperBound());
+  AddBoundTypeEntry(dwarf::DW_AT_byte_stride, GSR->getStride());
 }
 
 DIE *DwarfUnit::getIndexTyDie() {
@@ -1495,9 +1531,13 @@ void DwarfUnit::constructArrayTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
   DINodeArray Elements = CTy->getElements();
   for (unsigned i = 0, N = Elements.size(); i < N; ++i) {
     // FIXME: Should this really be such a loose cast?
-    if (auto *Element = dyn_cast_or_null<DINode>(Elements[i]))
+    if (auto *Element = dyn_cast_or_null<DINode>(Elements[i])) {
       if (Element->getTag() == dwarf::DW_TAG_subrange_type)
         constructSubrangeDIE(Buffer, cast<DISubrange>(Element), IdxTy);
+      else if (Element->getTag() == dwarf::DW_TAG_generic_subrange)
+        constructGenericSubrangeDIE(Buffer, cast<DIGenericSubrange>(Element),
+                                    IdxTy);
+    }
   }
 }
 

llvm/lib/CodeGen/AsmPrinter/DwarfUnit.h

@@ -301,6 +301,8 @@ class DwarfUnit : public DIEUnit {
   void constructTypeDIE(DIE &Buffer, const DIDerivedType *DTy);
   void constructTypeDIE(DIE &Buffer, const DISubroutineType *CTy);
   void constructSubrangeDIE(DIE &Buffer, const DISubrange *SR, DIE *IndexTy);
+  void constructGenericSubrangeDIE(DIE &Buffer, const DIGenericSubrange *SR,
+                                   DIE *IndexTy);
   void constructArrayTypeDIE(DIE &Buffer, const DICompositeType *CTy);
   void constructEnumTypeDIE(DIE &Buffer, const DICompositeType *CTy);
   DIE &constructMemberDIE(DIE &Buffer, const DIDerivedType *DT);

llvm/lib/IR/AsmWriter.cpp

@@ -1910,6 +1910,57 @@ static void writeDISubrange(raw_ostream &Out, const DISubrange *N,
   Out << ")";
 }
 
+static void writeDIGenericSubrange(raw_ostream &Out, const DIGenericSubrange *N,
+                                   TypePrinting *TypePrinter,
+                                   SlotTracker *Machine,
+                                   const Module *Context) {
+  Out << "!DIGenericSubrange(";
+  MDFieldPrinter Printer(Out, TypePrinter, Machine, Context);
+
+  auto IsConstant = [&](Metadata *Bound) -> bool {
+    if (auto *BE = dyn_cast_or_null<DIExpression>(Bound)) {
+      return BE->isSignedConstant();
+    }
+    return false;
+  };
+
+  auto GetConstant = [&](Metadata *Bound) -> int64_t {
+    assert(IsConstant(Bound) && "Expected constant");
+    auto *BE = dyn_cast_or_null<DIExpression>(Bound);
+    return static_cast<int64_t>(BE->getElement(1));
+  };
+
+  auto *Count = N->getRawCountNode();
+  if (IsConstant(Count))
+    Printer.printInt("count", GetConstant(Count),
+                     /* ShouldSkipZero */ false);
+  else
+    Printer.printMetadata("count", Count, /*ShouldSkipNull */ true);
+
+  auto *LBound = N->getRawLowerBound();
+  if (IsConstant(LBound))
+    Printer.printInt("lowerBound", GetConstant(LBound),
+                     /* ShouldSkipZero */ false);
+  else
+    Printer.printMetadata("lowerBound", LBound, /*ShouldSkipNull */ true);
+
+  auto *UBound = N->getRawUpperBound();
+  if (IsConstant(UBound))
+    Printer.printInt("upperBound", GetConstant(UBound),
+                     /* ShouldSkipZero */ false);
+  else
+    Printer.printMetadata("upperBound", UBound, /*ShouldSkipNull */ true);
+
+  auto *Stride = N->getRawStride();
+  if (IsConstant(Stride))
+    Printer.printInt("stride", GetConstant(Stride),
+                     /* ShouldSkipZero */ false);
+  else
+    Printer.printMetadata("stride", Stride, /*ShouldSkipNull */ true);
+
+  Out << ")";
+}
+
 static void writeDIEnumerator(raw_ostream &Out, const DIEnumerator *N,
                               TypePrinting *, SlotTracker *, const Module *) {
   Out << "!DIEnumerator(";