Convert UpdateExternalModuleListIfNeeded to use early exits.

Author: adrian-prantl

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

@@ -1618,72 +1618,72 @@ void SymbolFileDWARF::UpdateExternalModuleListIfNeeded() {
 
   DWARFDebugInfo *debug_info = DebugInfo();
 
+  // Follow DWO skeleton unit breadcrumbs.
   const uint32_t num_compile_units = GetNumCompileUnits();
   for (uint32_t cu_idx = 0; cu_idx < num_compile_units; ++cu_idx) {
     DWARFUnit *dwarf_cu = debug_info->GetUnitAtIndex(cu_idx);
-
     const DWARFBaseDIE die = dwarf_cu->GetUnitDIEOnly();
-    if (die && !die.HasChildren()) {
-      const char *name = die.GetAttributeValueAsString(DW_AT_name, nullptr);
-
-      if (name) {
-        ConstString const_name(name);
-        if (m_external_type_modules.find(const_name) ==
-            m_external_type_modules.end()) {
-          ModuleSP module_sp;
-          const char *dwo_path =
-              die.GetAttributeValueAsString(DW_AT_GNU_dwo_name, nullptr);
-          if (dwo_path) {
-            ModuleSpec dwo_module_spec;
-            dwo_module_spec.GetFileSpec().SetFile(dwo_path,
-                                                  FileSpec::Style::native);
-            if (dwo_module_spec.GetFileSpec().IsRelative()) {
-              const char *comp_dir =
-                  die.GetAttributeValueAsString(DW_AT_comp_dir, nullptr);
-              if (comp_dir) {
-                dwo_module_spec.GetFileSpec().SetFile(comp_dir,
-                                                      FileSpec::Style::native);
-                FileSystem::Instance().Resolve(dwo_module_spec.GetFileSpec());
-                dwo_module_spec.GetFileSpec().AppendPathComponent(dwo_path);
-              }
-            }
-            dwo_module_spec.GetArchitecture() =
-                m_objfile_sp->GetModule()->GetArchitecture();
-
-            // When LLDB loads "external" modules it looks at the presence of
-            // DW_AT_GNU_dwo_name. However, when the already created module
-            // (corresponding to .dwo itself) is being processed, it will see
-            // the presence of DW_AT_GNU_dwo_name (which contains the name of
-            // dwo file) and will try to call ModuleList::GetSharedModule
-            // again. In some cases (i.e. for empty files) Clang 4.0 generates
-            // a *.dwo file which has DW_AT_GNU_dwo_name, but no
-            // DW_AT_comp_dir. In this case the method
-            // ModuleList::GetSharedModule will fail and the warning will be
-            // printed. However, as one can notice in this case we don't
-            // actually need to try to load the already loaded module
-            // (corresponding to .dwo) so we simply skip it.
-            if (m_objfile_sp->GetFileSpec().GetFileNameExtension() == ".dwo" &&
-                llvm::StringRef(m_objfile_sp->GetFileSpec().GetPath())
-                    .endswith(dwo_module_spec.GetFileSpec().GetPath())) {
-              continue;
-            }
+    if (!die || die.HasChildren())
+      continue;
 
-            Status error = ModuleList::GetSharedModule(
-                dwo_module_spec, module_sp, nullptr, nullptr, nullptr);
-            if (!module_sp) {
-              GetObjectFile()->GetModule()->ReportWarning(
-                  "0x%8.8x: unable to locate module needed for external types: "
-                  "%s\nerror: %s\nDebugging will be degraded due to missing "
-                  "types. Rebuilding your project will regenerate the needed "
-                  "module files.",
-                  die.GetOffset(),
-                  dwo_module_spec.GetFileSpec().GetPath().c_str(),
-                  error.AsCString("unknown error"));
-            }
-          }
-          m_external_type_modules[const_name] = module_sp;
+    const char *name = die.GetAttributeValueAsString(DW_AT_name, nullptr);
+    if (!name)
+      continue;
+
+    ConstString const_name(name);
+    ModuleSP &module_sp = m_external_type_modules[const_name];
+    if (module_sp)
+      continue;
+
+    const char *dwo_path =
+        die.GetAttributeValueAsString(DW_AT_GNU_dwo_name, nullptr);
+    if (!dwo_path)
+      dwo_path = die.GetAttributeValueAsString(DW_AT_dwo_name, nullptr);
+    if (dwo_path) {
+      ModuleSpec dwo_module_spec;
+      dwo_module_spec.GetFileSpec().SetFile(dwo_path, FileSpec::Style::native);
+      if (dwo_module_spec.GetFileSpec().IsRelative()) {
+        const char *comp_dir =
+            die.GetAttributeValueAsString(DW_AT_comp_dir, nullptr);
+        if (comp_dir) {
+          dwo_module_spec.GetFileSpec().SetFile(comp_dir,
+                                                FileSpec::Style::native);
+          FileSystem::Instance().Resolve(dwo_module_spec.GetFileSpec());
+          dwo_module_spec.GetFileSpec().AppendPathComponent(dwo_path);
         }
       }
+      dwo_module_spec.GetArchitecture() =
+          m_objfile_sp->GetModule()->GetArchitecture();
+
+      // When LLDB loads "external" modules it looks at the presence
+      // of DW_AT_dwo_name. However, when the already created module
+      // (corresponding to .dwo itself) is being processed, it will
+      // see the presence of DW_AT_dwo_name (which contains the name
+      // of dwo file) and will try to call ModuleList::GetSharedModule
+      // again. In some cases (i.e., for empty files) Clang 4.0
+      // generates a *.dwo file which has DW_AT_dwo_name, but no
+      // DW_AT_comp_dir. In this case the method
+      // ModuleList::GetSharedModule will fail and the warning will be
+      // printed. However, as one can notice in this case we don't
+      // actually need to try to load the already loaded module
+      // (corresponding to .dwo) so we simply skip it.
+      if (m_objfile_sp->GetFileSpec().GetFileNameExtension() == ".dwo" &&
+          llvm::StringRef(m_objfile_sp->GetFileSpec().GetPath())
+              .endswith(dwo_module_spec.GetFileSpec().GetPath())) {
+        continue;
+      }
+
+      Status error = ModuleList::GetSharedModule(dwo_module_spec, module_sp,
+                                                 nullptr, nullptr, nullptr);
+      if (!module_sp) {
+        GetObjectFile()->GetModule()->ReportWarning(
+            "0x%8.8x: unable to locate module needed for external types: "
+            "%s\nerror: %s\nDebugging will be degraded due to missing "
+            "types. Rebuilding your project will regenerate the needed "
+            "module files.",
+            die.GetOffset(), dwo_module_spec.GetFileSpec().GetPath().c_str(),
+            error.AsCString("unknown error"));
+      }
     }
   }
 }