Fix warnings on Win64.

src/heap.cc

 // Copyright 2009 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 1854 matching lines @@
     String::WriteToFlat(buffer, dest, start, end);
   }
 
   return result;
 }
 
 
 Object* Heap::AllocateExternalStringFromAscii(
     ExternalAsciiString::Resource* resource) {
   Map* map;
-  int length = resource->length();
-  if (length <= String::kMaxShortSize) {
+  size_t length = resource->length();
+  if (length <= static_cast<size_t>(String::kMaxShortSize)) {
     map = short_external_ascii_string_map();
-  } else if (length <= String::kMaxMediumSize) {
+  } else if (length <= static_cast<size_t>(String::kMaxMediumSize)) {
     map = medium_external_ascii_string_map();
+  } else if (length <= static_cast<size_t>(String::kMaxLength)) {
+    map = long_external_ascii_string_map();
   } else {
-    map = long_external_ascii_string_map();
+    Top::context()->mark_out_of_memory();
+    return Failure::OutOfMemoryException();
   }
 
   Object* result = Allocate(map, NEW_SPACE);
   if (result->IsFailure()) return result;
 
   ExternalAsciiString* external_string = ExternalAsciiString::cast(result);
-  external_string->set_length(length);
+  external_string->set_length(static_cast<int>(length));
   external_string->set_resource(resource);
 
   return result;
 }
 
 
 Object* Heap::AllocateExternalStringFromTwoByte(
     ExternalTwoByteString::Resource* resource) {
-  int length = resource->length();
-
-  Map* map = ExternalTwoByteString::StringMap(length);
+  size_t length = resource->length();
+  if (length > static_cast<size_t>(String::kMaxLength)) {
+    Top::context()->mark_out_of_memory();
+    return Failure::OutOfMemoryException();
+  }
+  Map* map = ExternalTwoByteString::StringMap(static_cast<int>(length));
   Object* result = Allocate(map, NEW_SPACE);
   if (result->IsFailure()) return result;
 
   ExternalTwoByteString* external_string = ExternalTwoByteString::cast(result);
-  external_string->set_length(length);
+  external_string->set_length(static_cast<int>(length));
   external_string->set_resource(resource);
 
   return result;
 }
 
 
 Object* Heap::LookupSingleCharacterStringFromCode(uint16_t code) {
   if (code <= String::kMaxAsciiCharCode) {
     Object* value = Heap::single_character_string_cache()->get(code);
     if (value != Heap::undefined_value()) return value;
@@ skipping 2070 matching lines @@
   for (int i = 0; i < kNumberOfCaches; i++) {
     if (caches_[i] != NULL) {
       delete caches_[i];
       caches_[i] = NULL;
     }
   }
 }
 
 
 } }  // namespace v8::internal