[lldb] [llvm] Add support for using foreign type units in .debug_names. (PR #87740)

[Alex Langford via llvm-commits]

================
@@ -1726,44 +1725,59 @@ lldb::ModuleSP SymbolFileDWARF::GetExternalModule(ConstString name) {
   return pos->second;
 }
 
-DWARFDIE
-SymbolFileDWARF::GetDIE(const DIERef &die_ref) {
-  // This method can be called without going through the symbol vendor so we
-  // need to lock the module.
-  std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
-
-  SymbolFileDWARF *symbol_file = nullptr;
-
+SymbolFileDWARF *SymbolFileDWARF::GetDIERefSymbolFile(const DIERef &die_ref) {
   // Anytime we get a "lldb::user_id_t" from an lldb_private::SymbolFile API we
   // must make sure we use the correct DWARF file when resolving things. On
   // MacOSX, when using SymbolFileDWARFDebugMap, we will use multiple
   // SymbolFileDWARF classes, one for each .o file. We can often end up with
   // references to other DWARF objects and we must be ready to receive a
   // "lldb::user_id_t" that specifies a DIE from another SymbolFileDWARF
   // instance.
+
   std::optional<uint32_t> file_index = die_ref.file_index();
+
+  // If the file index matches, then we have the right SymbolFileDWARF already.
+  // This will work for both .dwo file and DWARF in .o files for mac. Also if
+  // both the file indexes are invalid, then we have a match.
+  if (GetFileIndex() == file_index)
+    return this;
+
+  // If we are currently in a .dwo file and our file index doesn't match we need
+  // to let the base symbol file handle this.
+  SymbolFileDWARFDwo *dwo = llvm::dyn_cast_or_null<SymbolFileDWARFDwo>(this);
+  if (dwo)
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bulbazord wrote:

nit: Merge these two lines

https://github.com/llvm/llvm-project/pull/87740