[lldb] Speed up check if C++ interop and embedded are enabled

Previously, we were parsing every compile unit to look up the flags that
indicate whether the current compile unit had C++ interop and/or embedded
Swift enabled. Change that to parse only the compile unit we're
interested in.

rdar://153198051

Author: augusto2112

lldb/include/lldb/Symbol/SymbolFile.h

@@ -387,6 +387,15 @@ class SymbolFile : public PluginInterface {
   /// for this module have been changed.
   virtual void SectionFileAddressesChanged() = 0;
 
+  /// Looks for the compile option specified by \p option, and sets \p value to
+  /// it's value. For example, for a flag such as -foo=bar, looking up \p option
+  /// "-foo" will set \p value to "bar". For a standalone flag such as -baz, \p
+  /// value will be empty.
+  ///
+  /// If \p cu is set, only that compile unit is searched. Otherwise, every
+  /// compile unit is searched until the option is found or failure.
+  ///
+  /// Returns true if the option is found.
   virtual bool GetCompileOption(const char *option, std::string &value,
                                 CompileUnit *cu = nullptr) {
     value.clear();

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

@@ -3253,6 +3253,36 @@ SymbolFileDWARF::FindDefinitionDIE(const DWARFDIE &die) {
   return result;
 }
 
+namespace {
+const char *GetFlags(const char *option, DWARFUnit *dwarf_cu) {
+  if (!dwarf_cu)
+    return nullptr;
+
+  const DWARFBaseDIE die = dwarf_cu->GetUnitDIEOnly();
+  if (!die)
+    return nullptr;
+
+  const char *flags = die.GetAttributeValueAsString(DW_AT_APPLE_flags, NULL);
+  if (!flags)
+    return nullptr;
+
+  if (strstr(flags, option))
+    return flags;
+
+  return nullptr;
+}
+bool FindOptionInDWARFCU(const char *option, DWARFUnit *dwarf_cu,
+                         std::string value) {
+  const char *flags = GetFlags(option, dwarf_cu);
+  if (!flags)
+    return false;
+
+  Args compiler_args(flags);
+  OptionParsing::GetOptionValueAsString(compiler_args, option, value);
+  return true;
+}
+} // namespace
+
 bool SymbolFileDWARF::GetCompileOption(const char *option, std::string &value,
                                        CompileUnit *cu) {
   value.clear();
@@ -3262,52 +3292,19 @@ bool SymbolFileDWARF::GetCompileOption(const char *option, std::string &value,
   const uint32_t num_compile_units = GetNumCompileUnits();
 
   if (cu) {
-    auto *dwarf_cu =
-        llvm::dyn_cast_or_null<DWARFCompileUnit>(GetDWARFCompileUnit(cu));
-
-    if (dwarf_cu) {
+    if (auto *dwarf_cu =
+            llvm::dyn_cast_or_null<DWARFCompileUnit>(GetDWARFCompileUnit(cu))) {
       // GetDWARFCompileUnit() only looks up by CU#. Make sure that
       // this is actually the correct SymbolFile by converting it
       // back to a CompileUnit.
       if (GetCompUnitForDWARFCompUnit(*dwarf_cu) != cu)
         return false;
-
-      const DWARFBaseDIE die = dwarf_cu->GetUnitDIEOnly();
-      if (die) {
-        const char *flags =
-            die.GetAttributeValueAsString(DW_AT_APPLE_flags, NULL);
-
-        if (flags) {
-          if (strstr(flags, option)) {
-            Args compiler_args(flags);
-
-            return OptionParsing::GetOptionValueAsString(compiler_args,
-                                                         option, value);
-          }
-        }
-      }
+      return FindOptionInDWARFCU(option, dwarf_cu, value);
     }
   } else {
-    for (uint32_t cu_idx = 0; cu_idx < num_compile_units; ++cu_idx) {
-      DWARFUnit *dwarf_cu = debug_info.GetUnitAtIndex(cu_idx);
-
-      if (dwarf_cu) {
-        const DWARFBaseDIE die = dwarf_cu->GetUnitDIEOnly();
-        if (die) {
-          const char *flags =
-              die.GetAttributeValueAsString(DW_AT_APPLE_flags, NULL);
-
-          if (flags) {
-            if (strstr(flags, option)) {
-              Args compiler_args(flags);
-
-              return OptionParsing::GetOptionValueAsString(compiler_args,
-                                                           option, value);
-            }
-          }
-        }
-      }
-    }
+    for (uint32_t cu_idx = 0; cu_idx < num_compile_units; ++cu_idx)
+      if (DWARFUnit *dwarf_cu = debug_info.GetUnitAtIndex(cu_idx))
+        return FindOptionInDWARFCU(option, dwarf_cu, value);
   }
 
   return false;

lldb/source/Plugins/TypeSystem/Swift/TypeSystemSwift.cpp

@@ -16,6 +16,7 @@
 #include "Plugins/LanguageRuntime/Swift/SwiftLanguageRuntime.h"
 #include "lldb/Core/PluginManager.h"
 #include "lldb/Symbol/CompileUnit.h"
+#include "lldb/Utility/LLDBLog.h"
 #include <lldb/lldb-enumerations.h>
 #include <llvm/ADT/StringRef.h>
 
@@ -74,7 +75,7 @@ void TypeSystemSwift::Terminate() {
 
 bool TypeSystemSwift::CheckFlagInCU(CompileUnit *cu, const char *flag) {
   AutoBool interop_enabled =
-    ModuleList::GetGlobalModuleListProperties().GetSwiftEnableCxxInterop();
+      ModuleList::GetGlobalModuleListProperties().GetSwiftEnableCxxInterop();
   switch (interop_enabled) {
   case AutoBool::True:
     return true;
@@ -90,17 +91,18 @@ bool TypeSystemSwift::CheckFlagInCU(CompileUnit *cu, const char *flag) {
     if (!sym_file)
       return false;
     auto options = sym_file->GetCompileOptions();
-    for (auto &[unit, args] : options) {
-      if (unit.get() == cu) {
-        if (cu->GetLanguage() == eLanguageTypeSwift)
-          for (const char *arg : args.GetArgumentArrayRef())
-            if (strcmp(arg, flag) == 0)
-              return true;
-        return false;
-      }
+    std::string value;
+    if (sym_file->GetCompileOption(flag, value, cu)) {
+      LLDB_LOGV(GetLog(LLDBLog::Types),
+                "[CheckFlagInCU] Found flag {0} in CU: {1}", flag,
+                cu->GetPrimaryFile().GetFilename().AsCString());
+      return true;
     }
   }
   }
+  LLDB_LOGV(GetLog(LLDBLog::Types),
+            "[CheckFlagInCU] Did not find flag {0} in CU: {1}", flag,
+            cu->GetPrimaryFile().GetFilename().AsCString());
   return false;
 }
 

lldb/test/API/lang/swift/cxx_interop/forward/expressions/TestSwiftForwardInteropExpressions.py

@@ -15,13 +15,14 @@ def setup(self, bkpt_str):
              self, bkpt_str, lldb.SBFileSpec('main.swift'))
          return thread
 
-    @skipIf(bugnumber='rdar://152745034')
     @skipIfLinux # rdar://106871422"
     @skipIf(setting=('symbols.use-swift-clangimporter', 'false')) # rdar://106871275
     @swiftTest
     def test(self):
         self.setup('Break here')
 
+        types_log = self.getBuildArtifact('types.log')
+        self.expect("log enable lldb types -v -f "+ types_log)
         # Check that we can call free functions.
         self.expect('expr returnsInt()', substrs=['Int32', '42'])
 
@@ -54,6 +55,9 @@ def test(self):
         # Check that po prints the fields of a base class
         self.expect('po cxxClass', substrs=['CxxClass', 'a : 100', 'b : 101'])
 
+        self.filecheck('platform shell cat "%s"' % types_log, __file__)
+        # CHECK: [CheckFlagInCU] Found flag -enable-experimental-cxx-interop in CU:
+
     @expectedFailureAll(bugnumber="rdar://106216567")
     @swiftTest
     def test_po_subclass(self):

lldb/test/API/lang/swift/embedded/expr/TestSwiftEmbeddedExpression.py

@@ -14,4 +14,10 @@ def test(self):
             self, "break here", lldb.SBFileSpec("main.swift")
         )
 
+        types_log = self.getBuildArtifact('types.log')
+        self.expect("log enable lldb types -v -f "+ types_log)
+
         self.expect("expr a.foo()", substrs=["(Int)", " = 16"])
+
+        self.filecheck('platform shell cat "%s"' % types_log, __file__)
+        # CHECK: [CheckFlagInCU] Found flag -enable-embedded-swift in CU: