Handle string + number in hydrogen.

src/code-stubs.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 551 matching lines @@
       right->ToInt32(&value) && can_encode_arg_value(value) &&
       (left_state_ == SMI || left_state_ == INT32) &&
       (result_state_ == NONE || !fixed_right_arg_.has_value);
 
   fixed_right_arg_ = Maybe<int32_t>(new_has_fixed_right_arg, value);
 
   if (result.has_value) UpdateStatus(result.value, &result_state_);
 
   State max_input = Max(left_state_, right_state_);
 
-  // TODO(olivf) Instead of doing this normalization we should have a Hydrogen
-  // version of the LookupNumberStringCache to avoid a converting StringAddStub.
-  if (left_state_ == STRING && right_state_ < STRING) {
-    right_state_ = GENERIC;
-  } else if (right_state_ == STRING && left_state_ < STRING) {
-    left_state_ = GENERIC;
-  } else if (!has_int_result() && op_ != Token::SHR &&
-             max_input <= NUMBER && max_input > result_state_) {
+  if (!has_int_result() && op_ != Token::SHR &&
+      max_input <= NUMBER && max_input > result_state_) {
     result_state_ = max_input;
   }
 
   ASSERT(result_state_ <= (has_int_result() ? INT32 : NUMBER) ||
          op_ == Token::ADD);
 
   if (old_state == GetExtraICState()) {
     // Tagged operations can lead to non-truncating HChanges
     if (left->IsUndefined()) {
       left_state_ = GENERIC;
@@ skipping 569 matching lines @@
   InstallDescriptor(isolate, &stub3);
 }
 
 InternalArrayConstructorStub::InternalArrayConstructorStub(
     Isolate* isolate) {
   InternalArrayConstructorStubBase::GenerateStubsAheadOfTime(isolate);
 }
 
 
 } }  // namespace v8::internal