[lldb] Add count for errors of DWO files in statistics and combine DWO file count functions (#155023)

## Summary
A new `totalDwoErrorCount` counter is available in statistics when
calling `statistics dump` to track the number of DWO errors.
Additionally, this PR refactors the DWO file statistics by consolidating
the existing functionality for counting loaded and total DWO files
together with the number of DWO errors into a single function that
returns a new DWOStats struct.

1. A new struct, `DWOStats` is created to hold the number of loaded DWO
files, the total number of DWO files and the number of DWO errors.
2. Replaced the previous `GetDwoFileCounts` function for loaded and
total DWO file counts with a single `GetDwoStats()` function returning
the struct `DWOStats`. An override is implemented for `SymbolFileDWARF`
that computes the new DWO error count alongside existing counts in one
pass. If the status of a DWO CU is `Fail`, which means there is error
happened during the loading process, we increment the DWO error counter.
_Note: The newly created function `GetDwoStats` will only be called when
we try to get statistics. Other codepaths will not be affected._
3. In Statistics, we sum up the total number of DWO file loading errors.
This is done by getting `DWOStats` for each symbol file and adding up
the results for each module, then adding to the total count among all
modules.
4. In Statistics, we also updated call sites to use the new combined
function and struct for loaded and total DWO file counts. As it is
possible for one module to have several symbol files, the DWO file
counts in a module's stats are updated to be calculated by adding up the
counts from all symbol files.

## Expected Behavior

- When binaries are compiled with split-dwarf and separate DWO files,
`totalDwoLoadErrorCount` would be the number of dwo files with error
occurs during the loading process, 0 if no error occurs during a loading
process.

- When not using split-dwarf, we expect `totalDwoLoadErrorCount` to be 0
since there no DWO file loading errors would be caused.

- `totalLoadedDwoFileCount` and `totalDwoFileCount` should be correctly
calculated after refactoring and updating.

## Testing
### Manual Testing
We created some files to simulate the possible DWO errors manually and
observed the results generated by statistics dump.
For example, if we delete one of the DWO files generated after
compiling, we would get:
```
(lldb) statistics dump
{
  ...
  "totalDwoLoadErrorCount": 1,
  ...
}
```
We also checked the time cost of `statistics dump` w/o the modification
to make sure no significant time cost increase imported.

### Unit test
Added two unit tests that build with new "dwo_error_foo.cpp" and
"dwo_error_main.cpp" files. For tests with flags -gsplit-dwarf, this
generates 2 DWO files.
In one of the tests, we delete both DWO files and check the result to
see if it reflects the number of DWO files with errors correctly. In
another test we update one of the files but loading the outdated .dwo
file of it, expecting it increments the error count by 1.
To run the test:
```
$ bin/lldb-dotest -p TestStats.py ~/local/llvm-project/lldb/test/API/commands/statistics/basic/ -G "dwo"
----------------------------------------------------------------------
Ran 27 tests in 2.680s

OK (skipped=21)

$ bin/lldb-dotest -p TestStats.py ~/local/llvm-project/lldb/test/API/commands/statistics/basic/
----------------------------------------------------------------------
Ran 27 tests in 370.131s

OK (skipped=3)
```

Author: zw3917

lldb/include/lldb/Symbol/SymbolFile.h

@@ -488,13 +488,16 @@ class SymbolFile : public PluginInterface {
     return false;
   };
 
-  /// Get number of loaded/parsed DWO files. This is emitted in "statistics
-  /// dump"
+  /// Retrieves statistics about DWO files associated with this symbol file.
+  /// This function returns a DWOStats struct containing:
+  ///   - The number of successfully loaded/parsed DWO files.
+  ///   - The total number of DWO files encountered.
+  ///   - The number of DWO CUs that failed to load due to errors.
+  /// If this symbol file does not support DWO files, all counts will be zero.
   ///
   /// \returns
-  ///     A pair containing (loaded_dwo_count, total_dwo_count). If this
-  ///     symbol file doesn't support DWO files, both counts will be 0.
-  virtual std::pair<uint32_t, uint32_t> GetDwoFileCounts() { return {0, 0}; }
+  ///   A DWOStats struct with loaded, total, and error counts for DWO files.
+  virtual DWOStats GetDwoStats() { return {}; }
 
   virtual lldb::TypeSP
   MakeType(lldb::user_id_t uid, ConstString name,

lldb/include/lldb/Target/Statistics.h

@@ -123,6 +123,19 @@ struct StatsSuccessFail {
   uint32_t failures = 0;
 };
 
+/// Holds statistics about DWO (Debug With Object) files.
+struct DWOStats {
+  uint32_t loaded_dwo_file_count = 0;
+  uint32_t dwo_file_count = 0;
+  uint32_t dwo_error_count = 0;
+
+  DWOStats operator+(const DWOStats &rhs) const {
+    return DWOStats{loaded_dwo_file_count + rhs.loaded_dwo_file_count,
+                    dwo_file_count + rhs.dwo_file_count,
+                    dwo_error_count + rhs.dwo_error_count};
+  }
+};
+
 /// A class that represents statistics for a since lldb_private::Module.
 struct ModuleStats {
   llvm::json::Value ToJSON() const;
@@ -153,8 +166,7 @@ struct ModuleStats {
   bool symtab_stripped = false;
   bool debug_info_had_variable_errors = false;
   bool debug_info_had_incomplete_types = false;
-  uint32_t dwo_file_count = 0;
-  uint32_t loaded_dwo_file_count = 0;
+  DWOStats dwo_stats;
 };
 
 struct ConstStringStats {

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

@@ -4502,9 +4502,8 @@ void SymbolFileDWARF::GetCompileOptions(
   }
 }
 
-std::pair<uint32_t, uint32_t> SymbolFileDWARF::GetDwoFileCounts() {
-  uint32_t total_dwo_count = 0;
-  uint32_t loaded_dwo_count = 0;
+DWOStats SymbolFileDWARF::GetDwoStats() {
+  DWOStats stats;
 
   DWARFDebugInfo &info = DebugInfo();
   const size_t num_cus = info.GetNumUnits();
@@ -4517,16 +4516,21 @@ std::pair<uint32_t, uint32_t> SymbolFileDWARF::GetDwoFileCounts() {
     if (!dwarf_cu->GetDWOId().has_value())
       continue;
 
-    total_dwo_count++;
+    stats.dwo_file_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++;
+      stats.loaded_dwo_file_count++;
     }
+
+    // Check if this unit has a DWO load error, false by default.
+    const Status &dwo_error = dwarf_cu->GetDwoError();
+    if (dwo_error.Fail())
+      stats.dwo_error_count++;
   }
 
-  return {loaded_dwo_count, total_dwo_count};
+  return stats;
 }

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

@@ -283,10 +283,11 @@ class SymbolFileDWARF : public SymbolFileCommon {
   bool GetSeparateDebugInfo(StructuredData::Dictionary &d, bool errors_only,
                             bool load_all_debug_info = false) 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;
+  /// Gets statistics about dwo files associated with this symbol file.
+  /// For split-dwarf files, this reports the counts for successfully loaded DWO
+  /// CUs, total DWO CUs, and the number of DWO CUs with loading errors.
+  /// For non-split-dwarf files, this reports 0 for all.
+  DWOStats GetDwoStats() override;
 
   DWARFContext &GetDWARFContext() { return m_context; }
 

lldb/source/Target/Statistics.cpp

@@ -73,8 +73,9 @@ 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);
+  module.try_emplace("dwoFileCount", dwo_stats.dwo_file_count);
+  module.try_emplace("loadedDwoFileCount", dwo_stats.loaded_dwo_file_count);
+  module.try_emplace("dwoErrorCount", dwo_stats.dwo_error_count);
 
   if (!symbol_locator_time.map.empty()) {
     json::Object obj;
@@ -324,8 +325,7 @@ 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;
+  DWOStats total_dwo_stats;
   for (size_t image_idx = 0; image_idx < num_modules; ++image_idx) {
     Module *module = target != nullptr
                          ? target->GetImages().GetModuleAtIndex(image_idx).get()
@@ -357,10 +357,9 @@ 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;
+      DWOStats current_dwo_stats = sym_file->GetDwoStats();
+      module_stat.dwo_stats = module_stat.dwo_stats + current_dwo_stats;
+      total_dwo_stats = total_dwo_stats + current_dwo_stats;
       module_stat.debug_info_index_loaded_from_cache =
           sym_file->GetDebugInfoIndexWasLoadedFromCache();
       if (module_stat.debug_info_index_loaded_from_cache)
@@ -435,8 +434,9 @@ 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},
+      {"totalLoadedDwoFileCount", total_dwo_stats.loaded_dwo_file_count},
+      {"totalDwoFileCount", total_dwo_stats.dwo_file_count},
+      {"totalDwoErrorCount", total_dwo_stats.dwo_error_count},
   };
 
   if (include_targets) {

lldb/test/API/commands/statistics/basic/TestStats.py

@@ -1,6 +1,8 @@
+import glob
 import json
 import os
 import re
+import shutil
 
 import lldb
 from lldbsuite.test.decorators import *
@@ -179,6 +181,7 @@ def test_default_no_run(self):
             "totalDebugInfoParseTime",
             "totalDwoFileCount",
             "totalLoadedDwoFileCount",
+            "totalDwoErrorCount",
         ]
         self.verify_keys(debug_stats, '"debug_stats"', debug_stat_keys, None)
         if self.getPlatform() != "windows":
@@ -291,6 +294,7 @@ def test_default_with_run(self):
             "totalDebugInfoParseTime",
             "totalDwoFileCount",
             "totalLoadedDwoFileCount",
+            "totalDwoErrorCount",
         ]
         self.verify_keys(debug_stats, '"debug_stats"', debug_stat_keys, None)
         stats = debug_stats["targets"][0]
@@ -331,6 +335,7 @@ def test_memory(self):
             "totalDebugInfoByteSize",
             "totalDwoFileCount",
             "totalLoadedDwoFileCount",
+            "totalDwoErrorCount",
         ]
         self.verify_keys(debug_stats, '"debug_stats"', debug_stat_keys, None)
 
@@ -385,6 +390,7 @@ def test_modules(self):
             "totalDebugInfoByteSize",
             "totalDwoFileCount",
             "totalLoadedDwoFileCount",
+            "totalDwoErrorCount",
         ]
         self.verify_keys(debug_stats, '"debug_stats"', debug_stat_keys, None)
         stats = debug_stats["targets"][0]
@@ -407,6 +413,7 @@ def test_modules(self):
             "symbolTableSavedToCache",
             "dwoFileCount",
             "loadedDwoFileCount",
+            "dwoErrorCount",
             "triple",
             "uuid",
         ]
@@ -497,6 +504,7 @@ def test_breakpoints(self):
             "totalDebugInfoByteSize",
             "totalDwoFileCount",
             "totalLoadedDwoFileCount",
+            "totalDwoErrorCount",
         ]
         self.verify_keys(debug_stats, '"debug_stats"', debug_stat_keys, None)
         target_stats = debug_stats["targets"][0]
@@ -655,6 +663,113 @@ def test_dwp_dwo_file_count(self):
         self.assertEqual(debug_stats["totalDwoFileCount"], 2)
         self.assertEqual(debug_stats["totalLoadedDwoFileCount"], 2)
 
+    @add_test_categories(["dwo"])
+    def test_dwo_missing_error_stats(self):
+        """
+        Test that DWO missing errors are reported correctly in statistics.
+        This test:
+        1) Builds a program with split DWARF (.dwo files)
+        2) Delete all two .dwo files
+        3) Verify that 2 DWO errors are reported in statistics
+        """
+        da = {
+            "CXX_SOURCES": "dwo_error_main.cpp dwo_error_foo.cpp",
+            "EXE": self.getBuildArtifact("a.out"),
+        }
+        # -gsplit-dwarf creates separate .dwo files,
+        # Expected output: dwo_error_main.dwo (contains main) and dwo_error_foo.dwo (contains foo struct/function)
+        self.build(dictionary=da, debug_info="dwo")
+        self.addTearDownCleanup(dictionary=da)
+        exe = self.getBuildArtifact("a.out")
+
+        # Remove the two .dwo files to trigger a DWO load error
+        dwo_files = glob.glob(self.getBuildArtifact("*.dwo"))
+        for dwo_file in dwo_files:
+            os.rename(dwo_file, dwo_file + ".bak")
+
+        target = self.createTestTarget(file_path=exe)
+        debug_stats = self.get_stats()
+
+        # Check DWO load error statistics are reported
+        self.assertIn("totalDwoErrorCount", debug_stats)
+        self.assertEqual(debug_stats["totalDwoErrorCount"], 2)
+
+        # Since there's only one module, module stats should have the same count as total count
+        self.assertIn("dwoErrorCount", debug_stats["modules"][0])
+        self.assertEqual(debug_stats["modules"][0]["dwoErrorCount"], 2)
+
+        # Restore the original .dwo file
+        for dwo_file in dwo_files:
+            os.rename(dwo_file + ".bak", dwo_file)
+
+    @add_test_categories(["dwo"])
+    def test_dwo_id_mismatch_error_stats(self):
+        """
+        Test that DWO ID mismatch errors are reported correctly in statistics.
+        This test:
+        1) Builds a program with split DWARF (.dwo files)
+        2) Change one of the source file content and rebuild
+        3) Replace the new .dwo file with the original one to create a DWO ID mismatch
+        4) Verifies that a DWO error is reported in statistics
+        5) Restores the original source file
+        """
+        da = {
+            "CXX_SOURCES": "dwo_error_main.cpp dwo_error_foo.cpp",
+            "EXE": self.getBuildArtifact("a.out"),
+        }
+        # -gsplit-dwarf creates separate .dwo files,
+        # Expected output: dwo_error_main.dwo (contains main) and dwo_error_foo.dwo (contains foo struct/function)
+        self.build(dictionary=da, debug_info="dwo")
+        self.addTearDownCleanup(dictionary=da)
+        exe = self.getBuildArtifact("a.out")
+
+        # Find and make a backup of the original .dwo file
+        dwo_files = glob.glob(self.getBuildArtifact("*.dwo"))
+
+        original_dwo_file = dwo_files[1]
+        original_dwo_backup = original_dwo_file + ".bak"
+        shutil.copy2(original_dwo_file, original_dwo_backup)
+
+        target = self.createTestTarget(file_path=exe)
+        initial_stats = self.get_stats()
+        self.assertIn("totalDwoErrorCount", initial_stats)
+        self.assertEqual(initial_stats["totalDwoErrorCount"], 0)
+        self.dbg.DeleteTarget(target)
+
+        # Get the original file size before modification
+        source_file_path = self.getSourcePath("dwo_error_foo.cpp")
+        original_size = os.path.getsize(source_file_path)
+
+        try:
+            # Modify the source code  and rebuild
+            with open(source_file_path, "a") as f:
+                f.write("\n void additional_foo(){}\n")
+
+            # Rebuild and replace the new .dwo file with the original one
+            self.build(dictionary=da, debug_info="dwo")
+            shutil.copy2(original_dwo_backup, original_dwo_file)
+
+            # Create a new target and run to a breakpoint to force DWO file loading
+            target = self.createTestTarget(file_path=exe)
+            debug_stats = self.get_stats()
+
+            # Check that DWO load error statistics are reported
+            self.assertIn("totalDwoErrorCount", debug_stats)
+            self.assertEqual(debug_stats["totalDwoErrorCount"], 1)
+
+            # Since there's only one module, module stats should have the same count as total count
+            self.assertIn("dwoErrorCount", debug_stats["modules"][0])
+            self.assertEqual(debug_stats["modules"][0]["dwoErrorCount"], 1)
+
+        finally:
+            # Remove the appended content
+            with open(source_file_path, "a") as f:
+                f.truncate(original_size)
+
+            # Restore the original .dwo file
+            if os.path.exists(original_dwo_backup):
+                os.unlink(original_dwo_backup)
+
     @skipUnlessDarwin
     @no_debug_info_test
     def test_dsym_binary_has_symfile_in_stats(self):

lldb/test/API/commands/statistics/basic/dwo_error_foo.cpp

@@ -0,0 +1,10 @@
+struct foo {
+  int x;
+  bool y;
+};
+
+void dwo_error_foo() {
+  foo f;
+  f.x = 1;
+  f.y = true;
+}

lldb/test/API/commands/statistics/basic/dwo_error_main.cpp

@@ -0,0 +1,5 @@
+void dwo_error_foo();
+int main() {
+  dwo_error_foo();
+  return 0;
+}