Add support for adding an external and a tagged pointer

src/hydrogen-instructions.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/base/bits.h"
 #include "src/double.h"
 #include "src/elements.h"
 #include "src/factory.h"
@@ skipping 1414 matching lines @@
   }
   // Optimize double negation, a common pattern used for ToInt32(x).
   HValue* arg;
   if (MatchDoubleNegation(this, &arg) && !arg->CheckFlag(kUint32)) {
     return arg;
   }
   return this;
 }
 
 
+// static
+HInstruction* HAdd::New(Isolate* isolate, Zone* zone, HValue* context,
+                        HValue* left, HValue* right, Strength strength,
+                        ExternalAddType external_add_type) {
+  // For everything else, you should use the other factory method without
+  // ExternalAddType.
+  DCHECK_EQ(external_add_type, AddOfExternalAndTagged);
+  return new (zone) HAdd(context, left, right, strength, external_add_type);
+}
+
+
 Representation HAdd::RepresentationFromInputs() {
   Representation left_rep = left()->representation();
   if (left_rep.IsExternal()) {
     return Representation::External();
   }
   return HArithmeticBinaryOperation::RepresentationFromInputs();
 }
 
 
 Representation HAdd::RequiredInputRepresentation(int index) {
   if (index == 2) {
     Representation left_rep = left()->representation();
     if (left_rep.IsExternal()) {
-      return Representation::Integer32();
+      if (external_add_type_ == AddOfExternalAndTagged) {
+        return Representation::Tagged();
+      } else {
+        return Representation::Integer32();
+      }
     }
   }
   return HArithmeticBinaryOperation::RequiredInputRepresentation(index);
 }
 
 
 static bool IsIdentityOperation(HValue* arg1, HValue* arg2, int32_t identity) {
   return arg1->representation().IsSpecialization() &&
     arg2->EqualsInteger32Constant(identity);
 }
@@ skipping 3268 matching lines @@
     case HObjectAccess::kExternalMemory:
       os << "[external-memory]";
       break;
   }
 
   return os << "@" << access.offset();
 }
 
 }  // namespace internal
 }  // namespace v8