[llvm] [DwarfDebug] Track abstract entities in DwarfUnit separately (PR #152680)

[David Blaikie via llvm-commits]

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@@ -53,6 +53,137 @@ struct RangeSpanList {
   SmallVector<RangeSpan, 2> Ranges;
 };
 
+/// Tracks abstract and concrete DIEs for debug info entities of a certain type.
+template <typename DINodeT, typename DbgEntityT> class DINodeInfoHolder {
+public:
+  using AbstractMapT = DenseMap<const DINodeT *, DIE *>;
+  using ConcreteMapT =
+      DenseMap<const DINodeT *, SmallDenseMap<const DbgEntityT *, DIE *, 2>>;
+
+private:
+  AbstractMapT AbstractMap;
+  ConcreteMapT ConcreteMap;
+
+public:
+  void insertAbstractDIE(const DINodeT *N, DIE *D) {
+    auto [_, Inserted] = AbstractMap.try_emplace(N, D);
+    assert(Inserted && "Duplicate abstract DIE for debug info node");
+  }
+
+  void insertConcreteDIE(const DINodeT *N, const DbgEntityT *E, DIE *D) {
+    auto [_, Inserted] = ConcreteMap[N].try_emplace(E, D);
+    assert(Inserted && "Duplicate concrete DIE for debug info node");
+  }
+
+  void insertDIE(const DINodeT *N, const DbgEntityT *E, DIE *D, bool Abstract) {
+    if (Abstract)
+      insertAbstractDIE(N, D);
+    else
+      insertConcreteDIE(N, E, D);
+  }
+
+  DIE *getAbstractDIE(const DINodeT *N) const { return AbstractMap.lookup(N); }
+
+  std::optional<
+      std::reference_wrapper<const typename ConcreteMapT::mapped_type>>
+  getConcreteDIEs(const DINodeT *N) const {
+    if (auto I = ConcreteMap.find(N); I != ConcreteMap.end())
+      return std::make_optional(std::ref(I->second));
+    return std::nullopt;
+  }
+
+  DIE *getConcreteDIE(const DINodeT *N, const DbgEntityT *E) const {
+    if (auto I = getConcreteDIEs(N))
+      return I->get().lookup(E);
+    return nullptr;
+  }
+
+  DIE *getAnyConcreteDIE(const DINodeT *N) const {
+    if (auto I = getConcreteDIEs(N))
+      return I->get().empty() ? nullptr : I->get().begin()->second;
+    return nullptr;
+  }
+
+  /// Returns abstract DIE for the entity.
+  /// If no abstract DIE was created, returns any concrete DIE for the entity.
+  DIE *getDIE(const DINodeT *N) const {
+    if (DIE *D = getAbstractDIE(N))
+      return D;
+
----------------
dwblaikie wrote:

Extra blank line could be removed to make this consistent with similar code above?

https://github.com/llvm/llvm-project/pull/152680