Clean up is-ASCII checks.

src/heap.cc

 // Copyright 2010 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 2531 matching lines @@
 
 MaybeObject* Heap::AllocateExternalStringFromTwoByte(
     ExternalTwoByteString::Resource* resource) {
   size_t length = resource->length();
   if (length > static_cast<size_t>(String::kMaxLength)) {
     Top::context()->mark_out_of_memory();
     return Failure::OutOfMemoryException();
   }
 
   // For small strings we check whether the resource contains only
-  // ascii characters.  If yes, we use a different string map.
-  bool is_ascii = true;
-  if (length >= static_cast<size_t>(String::kMinNonFlatLength)) {
-    is_ascii = false;
-  } else {
-    const uc16* data = resource->data();
-    for (size_t i = 0; i < length; i++) {
-      if (data[i] > String::kMaxAsciiCharCode) {
-        is_ascii = false;
-        break;
-      }
-    }
-  }
-
+  // ASCII characters.  If yes, we use a different string map.
+  static const size_t kAsciiCheckLengthLimit = 32;
+  bool is_ascii = length <= kAsciiCheckLengthLimit &&
+                  String::IsAscii(resource->data(), length);

[Mads Ager (chromium), 2010/12/22 07:46:24]

Four-space indent?

   Map* map = is_ascii ?
       Heap::external_string_with_ascii_data_map() : Heap::external_string_map();
   Object* result;
   { MaybeObject* maybe_result = Allocate(map, NEW_SPACE);
     if (!maybe_result->ToObject(&result)) return maybe_result;
   }
 
   ExternalTwoByteString* external_string = ExternalTwoByteString::cast(result);
   external_string->set_length(static_cast<int>(length));
   external_string->set_hash_field(String::kEmptyHashField);
@@ skipping 759 matching lines @@
     if (r > kMaxSupportedChar) { r = unibrow::Utf8::kBadChar; }
     string_result->Set(i, r);
   }
   return result;
 }
 
 
 MaybeObject* Heap::AllocateStringFromTwoByte(Vector<const uc16> string,
                                              PretenureFlag pretenure) {
   // Check if the string is an ASCII string.
-  int i = 0;
-  while (i < string.length() && string[i] <= String::kMaxAsciiCharCode) i++;
-
   MaybeObject* maybe_result;
-  if (i == string.length()) {  // It's an ASCII string.
+  if (String::IsAscii(string.start(), string.length())) {
     maybe_result = AllocateRawAsciiString(string.length(), pretenure);
   } else {  // It's not an ASCII string.
     maybe_result = AllocateRawTwoByteString(string.length(), pretenure);
   }
   Object* result;
   if (!maybe_result->ToObject(&result)) return maybe_result;
 
   // Copy the characters into the new object, which may be either ASCII or
   // UTF-16.
   String* string_result = String::cast(result);
@@ skipping 2153 matching lines @@
 void ExternalStringTable::TearDown() {
   new_space_strings_.Free();
   old_space_strings_.Free();
 }
 
 
 List<Object*> ExternalStringTable::new_space_strings_;
 List<Object*> ExternalStringTable::old_space_strings_;
 
 } }  // namespace v8::internal