Metadata: Add typed array-like wrapper for MDTuple

Add `MDTupleTypedArrayWrapper`, a wrapper around `MDTuple` that adapts
it to look like an array and cast its operands to the given type.  This
is designed to be a replacement for `DITypedArray<>`, which is in the
`DIDescriptor` hierarchy.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234183 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/DebugInfoMetadata.h

@@ -607,7 +607,7 @@ public:
     return cast_or_null<MDTuple>(getRawElements());
   }
   Metadata *getVTableHolder() const { return getRawVTableHolder(); }
-  MDTuple *getTemplateParams() const {
+  MDTemplateParameterArray getTemplateParams() const {
     return cast_or_null<MDTuple>(getRawTemplateParams());
   }
   StringRef getIdentifier() const { return getStringOperand(7); }
@@ -636,7 +636,7 @@ public:
   void replaceVTableHolder(Metadata *VTableHolder) {
     replaceOperandWith(5, VTableHolder);
   }
-  void replaceTemplateParams(MDTuple *TemplateParams) {
+  void replaceTemplateParams(MDTemplateParameterArray TemplateParams) {
     replaceOperandWith(6, TemplateParams);
   }
   /// @}
@@ -844,19 +844,19 @@ public:
   StringRef getProducer() const { return getStringOperand(1); }
   StringRef getFlags() const { return getStringOperand(2); }
   StringRef getSplitDebugFilename() const { return getStringOperand(3); }
-  MDTuple *getEnumTypes() const {
+  MDCompositeTypeArray getEnumTypes() const {
     return cast_or_null<MDTuple>(getRawEnumTypes());
   }
-  MDTuple *getRetainedTypes() const {
+  MDTypeArray getRetainedTypes() const {
     return cast_or_null<MDTuple>(getRawRetainedTypes());
   }
-  MDTuple *getSubprograms() const {
+  MDSubprogramArray getSubprograms() const {
     return cast_or_null<MDTuple>(getRawSubprograms());
   }
-  MDTuple *getGlobalVariables() const {
+  MDGlobalVariableArray getGlobalVariables() const {
     return cast_or_null<MDTuple>(getRawGlobalVariables());
   }
-  MDTuple *getImportedEntities() const {
+  MDImportedEntityArray getImportedEntities() const {
     return cast_or_null<MDTuple>(getRawImportedEntities());
   }
 
@@ -1103,13 +1103,13 @@ public:
   ConstantAsMetadata *getFunction() const {
     return cast_or_null<ConstantAsMetadata>(getRawFunction());
   }
-  MDTuple *getTemplateParams() const {
+  MDTemplateParameterArray getTemplateParams() const {
     return cast_or_null<MDTuple>(getRawTemplateParams());
   }
   MDSubprogram *getDeclaration() const {
     return cast_or_null<MDSubprogram>(getRawDeclaration());
   }
-  MDTuple *getVariables() const {
+  MDLocalVariableArray getVariables() const {
     return cast_or_null<MDTuple>(getRawVariables());
   }
 

include/llvm/IR/Metadata.h

@@ -1033,6 +1033,56 @@ void TempMDNodeDeleter::operator()(MDNode *Node) const {
   MDNode::deleteTemporary(Node);
 }
 
+/// \brief Typed iterator through MDNode operands.
+///
+/// An iterator that transforms an \a MDNode::iterator into an iterator over a
+/// particular Metadata subclass.
+template <class T>
+class TypedMDOperandIterator
+    : std::iterator<std::input_iterator_tag, T *, std::ptrdiff_t, void, T *> {
+  MDNode::op_iterator I;
+
+public:
+  explicit TypedMDOperandIterator(MDNode::op_iterator I) : I(I) {}
+  T *operator*() const { return cast_or_null<T>(*I); }
+  TypedMDOperandIterator &operator++() {
+    ++I;
+    return *this;
+  }
+  TypedMDOperandIterator operator++(int) {
+    TypedMDOperandIterator Temp(*this);
+    ++I;
+    return Temp;
+  }
+  bool operator==(const TypedMDOperandIterator &X) const { return I == X.I; }
+  bool operator!=(const TypedMDOperandIterator &X) const { return I != X.I; }
+};
+
+/// \brief Typed, array-like tuple of metadata.
+///
+/// This is a wrapper for \a MDTuple that makes it act like an array holding a
+/// particular type of metadata.
+template <class T> class MDTupleTypedArrayWrapper {
+  const MDTuple *N = nullptr;
+
+public:
+  MDTupleTypedArrayWrapper(const MDTuple *N) : N(N) {}
+  operator MDTuple *() const { return const_cast<MDTuple *>(N); }
+  MDTuple *operator->() const { return const_cast<MDTuple *>(N); }
+  MDTuple &operator*() const { return *const_cast<MDTuple *>(N); }
+
+  unsigned size() const { return N->getNumOperands(); }
+  T *operator[](unsigned I) const { return cast_or_null<T>(N->getOperand(I)); }
+
+  typedef TypedMDOperandIterator<T> iterator;
+  iterator begin() const { return iterator(N->op_begin()); }
+  iterator end() const { return iterator(N->op_end()); }
+};
+
+#define HANDLE_METADATA(CLASS)                                                 \
+  typedef MDTupleTypedArrayWrapper<CLASS> CLASS##Array;
+#include "llvm/IR/Metadata.def"
+
 //===----------------------------------------------------------------------===//
 /// \brief A tuple of MDNodes.
 ///

lib/IR/Verifier.cpp

@@ -3401,8 +3401,8 @@ void Verifier::verifyTypeRefs() {
 
   // Visit all the compile units again to check the type references.
   for (auto *CU : CUs->operands())
-    if (auto *Ts = cast<MDCompileUnit>(CU)->getRetainedTypes())
-      for (auto &Op : Ts->operands())
+    if (auto Ts = cast<MDCompileUnit>(CU)->getRetainedTypes())
+      for (MDType *Op : Ts)
         if (auto *T = dyn_cast<MDCompositeType>(Op))
           TypeRefs.erase(T->getRawIdentifier());
   if (TypeRefs.empty())