Replace PushIfAbsent by a Stack object

src/runtime/runtime-strings.cc

Index: src/runtime/runtime-strings.cc
diff --git a/src/runtime/runtime-strings.cc b/src/runtime/runtime-strings.cc
index 03b8a08afa09bea3a5936e67eb9ca1fed08abc4f..b109ae07b29e94d0a6efdfb97a6361405b40e287 100644
--- a/src/runtime/runtime-strings.cc
+++ b/src/runtime/runtime-strings.cc
@@ -497,89 +497,6 @@ RUNTIME_FUNCTION(Runtime_StringBuilderConcat) {
 }
 
 
-RUNTIME_FUNCTION(Runtime_StringBuilderJoin) {
-  HandleScope scope(isolate);
-  DCHECK(args.length() == 3);
-  CONVERT_ARG_HANDLE_CHECKED(JSArray, array, 0);
-  int32_t array_length;
-  if (!args[1]->ToInt32(&array_length)) {
-    THROW_NEW_ERROR_RETURN_FAILURE(isolate, NewInvalidStringLengthError());
-  }
-  CONVERT_ARG_HANDLE_CHECKED(String, separator, 2);
-  RUNTIME_ASSERT(array->HasFastObjectElements());
-  RUNTIME_ASSERT(array_length >= 0);
-
-  Handle<FixedArray> fixed_array(FixedArray::cast(array->elements()));
-  if (fixed_array->length() < array_length) {
-    array_length = fixed_array->length();
-  }
-
-  if (array_length == 0) {
-    return isolate->heap()->empty_string();
-  } else if (array_length == 1) {
-    Object* first = fixed_array->get(0);
-    RUNTIME_ASSERT(first->IsString());
-    return first;
-  }
-
-  int separator_length = separator->length();
-  RUNTIME_ASSERT(separator_length > 0);
-  int max_nof_separators =
-      (String::kMaxLength + separator_length - 1) / separator_length;
-  if (max_nof_separators < (array_length - 1)) {
-    THROW_NEW_ERROR_RETURN_FAILURE(isolate, NewInvalidStringLengthError());
-  }
-  int length = (array_length - 1) * separator_length;
-  for (int i = 0; i < array_length; i++) {
-    Object* element_obj = fixed_array->get(i);
-    RUNTIME_ASSERT(element_obj->IsString());
-    String* element = String::cast(element_obj);
-    int increment = element->length();
-    if (increment > String::kMaxLength - length) {
-      STATIC_ASSERT(String::kMaxLength < kMaxInt);
-      length = kMaxInt;  // Provoke exception;
-      break;
-    }
-    length += increment;
-  }
-
-  Handle<SeqTwoByteString> answer;
-  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-      isolate, answer, isolate->factory()->NewRawTwoByteString(length));
-
-  DisallowHeapAllocation no_gc;
-
-  uc16* sink = answer->GetChars();
-#ifdef DEBUG
-  uc16* end = sink + length;
-#endif
-
-  RUNTIME_ASSERT(fixed_array->get(0)->IsString());
-  String* first = String::cast(fixed_array->get(0));
-  String* separator_raw = *separator;
-  int first_length = first->length();
-  String::WriteToFlat(first, sink, 0, first_length);
-  sink += first_length;
-
-  for (int i = 1; i < array_length; i++) {
-    DCHECK(sink + separator_length <= end);
-    String::WriteToFlat(separator_raw, sink, 0, separator_length);
-    sink += separator_length;
-
-    RUNTIME_ASSERT(fixed_array->get(i)->IsString());
-    String* element = String::cast(fixed_array->get(i));
-    int element_length = element->length();
-    DCHECK(sink + element_length <= end);
-    String::WriteToFlat(element, sink, 0, element_length);
-    sink += element_length;
-  }
-  DCHECK(sink == end);
-
-  // Use %_FastOneByteArrayJoin instead.
-  DCHECK(!answer->IsOneByteRepresentation());
-  return *answer;
-}
-
 template <typename Char>
 static void JoinSparseArrayWithSeparator(FixedArray* elements,
                                          int elements_length,