[llvm] [BOLT][DWARF] Fix parent chain in debug_names entries with forward declaration. (PR #93865)

[Davide Italiano via llvm-commits]

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@@ -461,32 +461,42 @@ getUnitForOffset(DIEBuilder &Builder, DWARFContext &DWCtx,
   return nullptr;
 }
 
-uint32_t DIEBuilder::finalizeDIEs(
-    DWARFUnit &CU, DIE &Die,
-    std::vector<std::optional<BOLTDWARF5AccelTableData *>> &Parents,
-    uint32_t &CurOffset) {
+uint32_t
+DIEBuilder::finalizeDIEs(DWARFUnit &CU, DIE &Die,
+                         std::optional<BOLTDWARF5AccelTableData *> Parent,
+                         uint32_t NumberParentsInChain, uint32_t &CurOffset) {
   getState().DWARFDieAddressesParsed.erase(Die.getOffset());
   uint32_t CurSize = 0;
   Die.setOffset(CurOffset);
   std::optional<BOLTDWARF5AccelTableData *> NameEntry =
       DebugNamesTable.addAccelTableEntry(
           CU, Die, SkeletonCU ? SkeletonCU->getDWOId() : std::nullopt,
-          Parents.back());
+          NumberParentsInChain, Parent);
   // It is possible that an indexed debugging information entry has a parent
   // that is not indexed (for example, if its parent does not have a name
   // attribute). In such a case, a parent attribute may point to a nameless
   // index entry (that is, one that cannot be reached from any entry in the name
   // table), or it may point to the nearest ancestor that does have an index
   // entry.
+  // Although as discussed in https://github.com/llvm/llvm-project/pull/91808
+  // skipping entry is not very useful. So this follows clang where children of
+  // forward declaration won't have DW_IDX_parent.
+
+  // If Parent is nullopt and NumberParentsInChain is not zero, then forward
+  // declaration was encountered in this DF traversal. Propogating nullopt for
----------------
dcci wrote:

propogating -> propagating.

https://github.com/llvm/llvm-project/pull/93865