[llvm] [BOLT][DWARF] Add support for transitive DW_AT_name/DW_AT_linkage_name resolution for DW_AT_name/DW_AT_linkage_name. (PR #119493)

[Davide Italiano via llvm-commits]

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@@ -359,24 +339,97 @@ DWARF5AcceleratorTable::addAccelTableEntry(
                   << ".\n";
         return std::nullopt;
       }
-      EntryDie = Iter->second;
-    } else {
-      const DIEEntry &DIEENtry = Value.getDIEEntry();
-      EntryDie = &DIEENtry.getEntry();
+      return Iter->second;
     }
-
-    addEntry(EntryDie->findAttribute(dwarf::Attribute::DW_AT_linkage_name));
-    return addEntry(EntryDie->findAttribute(dwarf::Attribute::DW_AT_name));
+    const DIEEntry &DIEENtry = Value.getDIEEntry();
+    return {{&Unit, &DIEENtry.getEntry()}};
   };
 
-  if (std::optional<BOLTDWARF5AccelTableData *> Entry =
-          processReferencedDie(dwarf::Attribute::DW_AT_abstract_origin))
+  DIEValue AttrValLinkageName;
+  DIEValue AttrValName = Die.findAttribute(dwarf::Attribute::DW_AT_name);
+  DWARFUnit *RefUnit = &Unit;
+  const DIE *RefDieUsed = &Die;
+  // It is possible to have DW_TAG_subprogram only with  DW_AT_linkage_name that
+  // DW_AT_abstract_origin/DW_AT_specification point to.
+  while (!AttrValName) {
+    std::optional<std::pair<DWARFUnit *, const DIE *>> RefDUDie =
+        getReferenceDie(Value, RefDieUsed);
+    if (!RefDUDie)
+      break;
+    RefUnit = RefDUDie->first;
+    const DIE &RefDie = *RefDUDie->second;
+    RefDieUsed = &RefDie;
+    if (!AttrValLinkageName)
+      AttrValLinkageName =
+          RefDie.findAttribute(dwarf::Attribute::DW_AT_linkage_name);
+    AttrValName = RefDie.findAttribute(dwarf::Attribute::DW_AT_name);
+    Value = RefDie.findAttribute(dwarf::Attribute::DW_AT_abstract_origin);
+    if (!Value)
+      Value = RefDie.findAttribute(dwarf::Attribute::DW_AT_specification);
+  }
+  addEntry(Unit, Die, DWOID, Parent,
+           getName(*RefUnit, DWOID, NameToUse, AttrValLinkageName),
+           NumberParentsInChain);
+  return addEntry(Unit, Die, DWOID, Parent,
+                  getName(*RefUnit, DWOID, NameToUse, AttrValName),
+                  NumberParentsInChain);
+}
+
+std::optional<BOLTDWARF5AccelTableData *>
+DWARF5AcceleratorTable::addAccelTableEntry(
+    DWARFUnit &Unit, const DIE &Die, const std::optional<uint64_t> &DWOID,
+    const uint32_t NumberParentsInChain,
+    std::optional<BOLTDWARF5AccelTableData *> &Parent) {
+  if (Unit.getVersion() < 5 || !NeedToCreate)
+    return std::nullopt;
+  std::string NameToUse = "";
+
+  if (!canProcess(Unit, Die, NameToUse, false))
+    return std::nullopt;
+
+  // Addes a Unit to either CU, LocalTU or ForeignTU list the first time we
+  // encounter it.
+  // Invoking it here so that we don't add Units that don't have any entries.
+  if (&Unit != CurrentUnit) {
+    CurrentUnit = &Unit;
+    addUnit(Unit, DWOID);
+  }
+
+  // Minor optimization not to add entry twice for DW_TAG_namespace if it has no
+  // DW_AT_name.
+  std::optional<BOLTDWARF5AccelTableData *> LinkageEntry = std::nullopt;
+  DIEValue NameVal = Die.findAttribute(dwarf::Attribute::DW_AT_name);
+  DIEValue LinkageNameVal =
+      Die.findAttribute(dwarf::Attribute::DW_AT_linkage_name);
+  if (!(Die.getTag() == dwarf::DW_TAG_namespace && !NameVal))
+    LinkageEntry = addEntry(Unit, Die, DWOID, Parent,
+                            getName(Unit, DWOID, NameToUse, LinkageNameVal),
+                            NumberParentsInChain);
+
+  std::optional<BOLTDWARF5AccelTableData *> NameEntry =
+      addEntry(Unit, Die, DWOID, Parent,
+               getName(Unit, DWOID, NameToUse, NameVal), NumberParentsInChain);
+  if (NameEntry)
+    return NameEntry;
+
+  // The DIE doesn't have DW_AT_name or DW_AT_linkage_name, so we need to see if
+  // we can follow other attributes to find them. For the purposes of
+  // determining whether a debugging information entry has a particular
----------------
dcci wrote:

debugging -> debug.

https://github.com/llvm/llvm-project/pull/119493