Use the BitField class for Code::Flags.

src/compiler.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 31 matching lines @@
 class CompilationInfo BASE_EMBEDDED {
  public:
   explicit CompilationInfo(Handle<Script> script);
   explicit CompilationInfo(Handle<SharedFunctionInfo> shared_info);
   explicit CompilationInfo(Handle<JSFunction> closure);
 
   Isolate* isolate() {
     ASSERT(Isolate::Current() == isolate_);
     return isolate_;
   }
-  bool is_lazy() const { return (flags_ & IsLazy::mask()) != 0; }
-  bool is_eval() const { return (flags_ & IsEval::mask()) != 0; }
-  bool is_global() const { return (flags_ & IsGlobal::mask()) != 0; }
-  bool is_strict_mode() const { return (flags_ & IsStrictMode::mask()) != 0; }
-  bool is_in_loop() const { return (flags_ & IsInLoop::mask()) != 0; }
+  bool is_lazy() const { return IsLazy::decode(flags_); }
+  bool is_eval() const { return IsEval::decode(flags_); }
+  bool is_global() const { return IsGlobal::decode(flags_); }
+  bool is_strict_mode() const { return IsStrictMode::decode(flags_); }
+  bool is_in_loop() const { return IsInLoop::decode(flags_); }
   FunctionLiteral* function() const { return function_; }
   Scope* scope() const { return scope_; }
   Handle<Code> code() const { return code_; }
   Handle<JSFunction> closure() const { return closure_; }
   Handle<SharedFunctionInfo> shared_info() const { return shared_info_; }
   Handle<Script> script() const { return script_; }
   v8::Extension* extension() const { return extension_; }
   ScriptDataImpl* pre_parse_data() const { return pre_parse_data_; }
   Handle<Context> calling_context() const { return calling_context_; }
   int osr_ast_id() const { return osr_ast_id_; }
@@ skipping 231 matching lines @@
 
   static void RecordFunctionCompilation(Logger::LogEventsAndTags tag,
                                         CompilationInfo* info,
                                         Handle<SharedFunctionInfo> shared);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_COMPILER_H_