Reland "[lldb] Add count for number of DWO files loaded in statistics #144424" (#145572)

This relands changes in #144424 for adding a count of DWO files
parsed/loaded and the total number of DWO files.

The previous PR was reverted in #145494 due to the newly added unit
tests failing on Windows and MacOS CIs since these platforms don't
support DWO. This change add an additional
`@add_test_categories(["dwo"])` to the new tests to
[skip](cd46354dbd/lldb/packages/Python/lldbsuite/test/test_categories.py (L56))
these tests on Windows/MacOS.

Original PR: #144424

### Testing
Ran unit tests
```
$ bin/lldb-dotest -p TestStats.py llvm-project/lldb/test/API/commands/statistics/basic/
----------------------------------------------------------------------
Ran 24 tests in 211.391s

OK (skipped=3)
```

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp

@@ -4420,3 +4420,32 @@ void SymbolFileDWARF::GetCompileOptions(
     args.insert({comp_unit, Args(flags)});
   }
 }
+
+std::pair<uint32_t, uint32_t> SymbolFileDWARF::GetDwoFileCounts() {
+  uint32_t total_dwo_count = 0;
+  uint32_t loaded_dwo_count = 0;
+
+  DWARFDebugInfo &info = DebugInfo();
+  const size_t num_cus = info.GetNumUnits();
+  for (size_t cu_idx = 0; cu_idx < num_cus; cu_idx++) {
+    DWARFUnit *dwarf_cu = info.GetUnitAtIndex(cu_idx);
+    if (dwarf_cu == nullptr)
+      continue;
+
+    // Check if this is a DWO unit by checking if it has a DWO ID.
+    if (!dwarf_cu->GetDWOId().has_value())
+      continue;
+
+    total_dwo_count++;
+
+    // If we have a DWO symbol file, that means we were able to successfully
+    // load it.
+    SymbolFile *dwo_symfile =
+        dwarf_cu->GetDwoSymbolFile(/*load_all_debug_info=*/false);
+    if (dwo_symfile) {
+      loaded_dwo_count++;
+    }
+  }
+
+  return {loaded_dwo_count, total_dwo_count};
+}

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h

@@ -282,6 +282,11 @@ public:
   bool GetSeparateDebugInfo(StructuredData::Dictionary &d,
                             bool errors_only) override;
 
+  // Gets a pair of loaded and total dwo file counts.
+  // For split-dwarf files, this reports the counts for successfully loaded DWO
+  // CUs and total DWO CUs. For non-split-dwarf files, this reports 0 for both.
+  std::pair<uint32_t, uint32_t> GetDwoFileCounts() override;
+
   DWARFContext &GetDWARFContext() { return m_context; }
 
   const std::shared_ptr<SymbolFileDWARFDwo> &GetDwpSymbolFile();

lldb/source/Target/Statistics.cpp

@@ -73,6 +73,8 @@ json::Value ModuleStats::ToJSON() const {
                      debug_info_had_incomplete_types);
   module.try_emplace("symbolTableStripped", symtab_stripped);
   module.try_emplace("symbolTableSymbolCount", symtab_symbol_count);
+  module.try_emplace("dwoFileCount", dwo_file_count);
+  module.try_emplace("loadedDwoFileCount", loaded_dwo_file_count);
 
   if (!symbol_locator_time.map.empty()) {
     json::Object obj;
@@ -86,7 +88,7 @@ json::Value ModuleStats::ToJSON() const {
 
   if (!symfile_modules.empty()) {
     json::Array symfile_ids;
-    for (const auto symfile_id: symfile_modules)
+    for (const auto symfile_id : symfile_modules)
       symfile_ids.emplace_back(symfile_id);
     module.try_emplace("symbolFileModuleIdentifiers", std::move(symfile_ids));
   }
@@ -322,6 +324,8 @@ llvm::json::Value DebuggerStats::ReportStatistics(
   uint32_t num_modules_with_incomplete_types = 0;
   uint32_t num_stripped_modules = 0;
   uint32_t symtab_symbol_count = 0;
+  uint32_t total_loaded_dwo_file_count = 0;
+  uint32_t total_dwo_file_count = 0;
   for (size_t image_idx = 0; image_idx < num_modules; ++image_idx) {
     Module *module = target != nullptr
                          ? target->GetImages().GetModuleAtIndex(image_idx).get()
@@ -353,6 +357,10 @@ llvm::json::Value DebuggerStats::ReportStatistics(
         for (const auto &symbol_module : symbol_modules.Modules())
           module_stat.symfile_modules.push_back((intptr_t)symbol_module.get());
       }
+      std::tie(module_stat.loaded_dwo_file_count, module_stat.dwo_file_count) =
+          sym_file->GetDwoFileCounts();
+      total_dwo_file_count += module_stat.dwo_file_count;
+      total_loaded_dwo_file_count += module_stat.loaded_dwo_file_count;
       module_stat.debug_info_index_loaded_from_cache =
           sym_file->GetDebugInfoIndexWasLoadedFromCache();
       if (module_stat.debug_info_index_loaded_from_cache)
@@ -427,6 +435,8 @@ llvm::json::Value DebuggerStats::ReportStatistics(
       {"totalDebugInfoEnabled", num_debug_info_enabled_modules},
       {"totalSymbolTableStripped", num_stripped_modules},
       {"totalSymbolTableSymbolCount", symtab_symbol_count},
+      {"totalLoadedDwoFileCount", total_loaded_dwo_file_count},
+      {"totalDwoFileCount", total_dwo_file_count},
   };
 
   if (include_targets) {