[lldb] Add a setting to allow Swift AST context instantiations

lldb/include/lldb/Core/ModuleList.h

@@ -95,6 +95,7 @@ class ModuleListProperties : public Properties {
 
   AutoBool GetSwiftEnableCxxInterop() const;
   AutoBool GetSwiftEnableFullDwarfDebugging() const;
+  bool GetSwiftEnableASTContext() const;
   // END SWIFT
 
   FileSpec GetClangModulesCachePath() const;

lldb/source/Core/CoreProperties.td

@@ -64,6 +64,10 @@ let Definition = "modulelist" in {
     DefaultEnumValue<"llvm::to_underlying(AutoBool::Auto)">,
     EnumValues<"OptionEnumValues(g_enable_full_dwarf_debugging)">,
     Desc<"Read full debug information from DWARF for Swift debugging. By default LLDB will use DWARF debug information if it cannot use reflection metadata.">;
+  def SwiftEnableASTContext: Property<"swift-enable-ast-context", "Boolean">,
+    Global,
+    DefaultTrue,
+    Desc<"Enable instantiating Swift AST contexts.">;
 // END SWIFT
   def SymLinkPaths: Property<"debug-info-symlink-paths", "FileSpecList">,
     Global,

lldb/source/Core/ModuleList.cpp

@@ -274,6 +274,12 @@ AutoBool ModuleListProperties::GetSwiftEnableFullDwarfDebugging() const {
       idx, static_cast<AutoBool>(
                g_modulelist_properties[idx].default_uint_value));
 }
+
+bool ModuleListProperties::GetSwiftEnableASTContext() const {
+  const uint32_t idx = ePropertySwiftEnableASTContext;
+  return GetPropertyAtIndexAs<bool>(
+      idx, g_modulelist_properties[idx].default_uint_value != 0);
+}
 // END SWIFT
 
 FileSpec ModuleListProperties::GetLLDBIndexCachePath() const {

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

@@ -976,6 +976,10 @@ SwiftASTContext::SwiftASTContext(std::string description,
     : TypeSystemSwift(), m_typeref_typesystem(&typeref_typesystem),
       m_compiler_invocation_ap(new swift::CompilerInvocation()),
       m_diagnostic_consumer_ap(new StoringDiagnosticConsumer(*this)) {
+  assert(
+      ModuleList::GetGlobalModuleListProperties().GetSwiftEnableASTContext() &&
+      "Swift AST context instantiation is disabled!");
+
   m_description = description;
 
   // Set the clang modules cache path.
@@ -1884,6 +1888,10 @@ SwiftASTContext::CreateInstance(lldb::LanguageType language, Module &module,
   if (!SwiftASTContextSupportsLanguage(language))
     return lldb::TypeSystemSP();
 
+  if (!ModuleList::GetGlobalModuleListProperties()
+           .GetSwiftEnableASTContext())
+    return lldb::TypeSystemSP();
+
   std::string m_description;
   {
     llvm::raw_string_ostream ss(m_description);
@@ -2359,6 +2367,10 @@ lldb::TypeSystemSP SwiftASTContext::CreateInstance(
   if (!SwiftASTContextSupportsLanguage(language))
     return lldb::TypeSystemSP();
 
+  if (!ModuleList::GetGlobalModuleListProperties()
+           .GetSwiftEnableASTContext())
+    return lldb::TypeSystemSP();
+
   LLDB_SCOPED_TIMER();
   std::string m_description = "SwiftASTContextForExpressions";
   std::vector<swift::PluginSearchOption> plugin_search_options;
@@ -2650,6 +2662,10 @@ lldb::TypeSystemSP SwiftASTContext::CreateInstance(
     TypeSystemSwiftTypeRefForExpressions &typeref_typesystem) {
   LLDB_SCOPED_TIMER();
 
+  if (!ModuleList::GetGlobalModuleListProperties()
+           .GetSwiftEnableASTContext())
+    return lldb::TypeSystemSP();
+
   CompileUnit *cu = sc.comp_unit;
   StringRef swift_module_name = TypeSystemSwiftTypeRef::GetSwiftModuleFor(&sc);
   std::string m_description;