Calling a generator function returns a generator object

src/objects-debug.cc

 // Copyright 2012 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 121 matching lines @@
     case CODE_TYPE:
       Code::cast(this)->CodeVerify();
       break;
     case ODDBALL_TYPE:
       Oddball::cast(this)->OddballVerify();
       break;
     case JS_OBJECT_TYPE:
     case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
       JSObject::cast(this)->JSObjectVerify();
       break;
+    case JS_GENERATOR_OBJECT_TYPE:
+      JSGeneratorObject::cast(this)->JSGeneratorObjectVerify();
+      break;
     case JS_MODULE_TYPE:
       JSModule::cast(this)->JSModuleVerify();
       break;
     case JS_VALUE_TYPE:
       JSValue::cast(this)->JSValueVerify();
       break;
     case JS_DATE_TYPE:
       JSDate::cast(this)->JSDateVerify();
       break;
     case JS_FUNCTION_TYPE:
@@ skipping 245 matching lines @@
       double value = get_scalar(i);
       CHECK(!isnan(value) ||
              (BitCast<uint64_t>(value) ==
               BitCast<uint64_t>(canonical_not_the_hole_nan_as_double())) ||
              ((BitCast<uint64_t>(value) & Double::kSignMask) != 0));
     }
   }
 }
 
 
+void JSGeneratorObject::JSGeneratorObjectVerify() {
+  // In an expression like "new g()", there can be a point where a generator
+  // object is allocated but its fields are all undefined, as it hasn't yet been
+  // initialized by the generator.  Hence these weak checks.
+  VerifyObjectField(kFunctionOffset);
+  VerifyObjectField(kContextOffset);
+  VerifyObjectField(kOperandStackOffset);
+  VerifyObjectField(kContinuationOffset);
+}
+
+
 void JSModule::JSModuleVerify() {
   VerifyObjectField(kContextOffset);
   VerifyObjectField(kScopeInfoOffset);
   CHECK(context()->IsUndefined() ||
         Context::cast(context())->IsModuleContext());
 }
 
 
 void JSValue::JSValueVerify() {
   Object* v = value();
@@ skipping 654 matching lines @@
   for (int i = 0; i < number_of_transitions(); ++i) {
     if (!CheckOneBackPointer(current_map, GetTarget(i))) return false;
   }
   return true;
 }
 
 
 #endif  // DEBUG
 
 } }  // namespace v8::internal