[llvm] [AsmPrinter][DebugNames] Implement DW_IDX_parent entries (PR #77457)

[Jonas Devlieghere via llvm-commits]

================
@@ -282,19 +299,45 @@ class DWARF5AccelTableData : public AccelTableData {
     assert(isNormalized() && "Accessing DIE Offset before normalizing.");
     return std::get<uint64_t>(OffsetVal);
   }
+
+  OffsetAndUnitID getDieOffsetAndUnitID() const {
+    return {getDieOffset(), UnitID};
+  }
+
   unsigned getDieTag() const { return DieTag; }
   unsigned getUnitID() const { return UnitID; }
   bool isTU() const { return IsTU; }
   void normalizeDIEToOffset() {
     assert(!isNormalized() && "Accessing offset after normalizing.");
-    OffsetVal = std::get<const DIE *>(OffsetVal)->getOffset();
+    const DIE *Entry = std::get<const DIE *>(OffsetVal);
+    ParentOffset = getDefiningParentDieOffset(*Entry);
+    OffsetVal = Entry->getOffset();
   }
   bool isNormalized() const {
     return std::holds_alternative<uint64_t>(OffsetVal);
   }
 
+  std::optional<uint64_t> getParentDieOffset() const {
+    auto OffsetAndId = getParentDieOffsetAndUnitID();
+    if (!OffsetAndId)
+      return {};
+    return OffsetAndId->offset();
----------------
JDevlieghere wrote:

Save one line? ;-) 
```
if (auto OffsetAndId = getParentDieOffsetAndUnitID()) 
  return OffsetAndId->offset();
return {};
```

https://github.com/llvm/llvm-project/pull/77457