Tentative implementation of string slices (hidden under the flag --string-slices).

src/runtime.cc

 // Copyright 2011 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 3563 matching lines @@
   // No matches at all, return failure or exception result directly.
   return result;
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_RegExpExecMultiple) {
   ASSERT(args.length() == 4);
   HandleScope handles(isolate);
 
   CONVERT_ARG_CHECKED(String, subject, 1);
-  if (!subject->IsFlat()) { FlattenString(subject); }
+  if (!subject->IsFlatAndTruncated()) FlattenOrTruncateString(subject);
   CONVERT_ARG_CHECKED(JSRegExp, regexp, 0);
   CONVERT_ARG_CHECKED(JSArray, last_match_info, 2);
   CONVERT_ARG_CHECKED(JSArray, result_array, 3);
 
   ASSERT(last_match_info->HasFastElements());
   ASSERT(regexp->GetFlags().is_global());
   Handle<FixedArray> result_elements;
   if (result_array->HasFastElements()) {
     result_elements =
         Handle<FixedArray>(FixedArray::cast(result_array->elements()));
@@ skipping 9156 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal