Add heuristic for flattening strings before comparing them.

src/runtime.cc

 // Copyright 2006-2009 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 5055 matching lines @@
     prefix_length = y->length();
     equal_prefix_result = Smi::FromInt(GREATER);
   } else if (y->length() > prefix_length) {
     equal_prefix_result = Smi::FromInt(LESS);
   }
   int r;
   if (x->IsAsciiRepresentation()) {
     Vector<const char> x_chars = x->ToAsciiVector();
     if (y->IsAsciiRepresentation()) {
       Vector<const char> y_chars = y->ToAsciiVector();
-      r = memcmp(x_chars.start(), y_chars.start(), prefix_length);
+      r = CompareChars(x_chars.start(), y_chars.start(), prefix_length);
     } else {
       Vector<const uc16> y_chars = y->ToUC16Vector();
       r = CompareChars(x_chars.start(), y_chars.start(), prefix_length);
     }
   } else {
     Vector<const uc16> x_chars = x->ToUC16Vector();
     if (y->IsAsciiRepresentation()) {
       Vector<const char> y_chars = y->ToAsciiVector();
       r = CompareChars(x_chars.start(), y_chars.start(), prefix_length);
     } else {
@@ skipping 27 matching lines @@
     if (x->length() == 0) return Smi::FromInt(EQUAL);
     return Smi::FromInt(GREATER);
   } else if (x->length() == 0) {
     return Smi::FromInt(LESS);
   }
 
   int d = x->Get(0) - y->Get(0);
   if (d < 0) return Smi::FromInt(LESS);
   else if (d > 0) return Smi::FromInt(GREATER);
 
-  x->TryFlatten();
-  y->TryFlatten();
+  Object* obj = Heap::PrepareForCompare(x);
+  if (obj->IsFailure()) return obj;
+  obj = Heap::PrepareForCompare(y);
+  if (obj->IsFailure()) return obj;
 
   return (x->IsFlat() && y->IsFlat()) ? FlatStringCompare(x, y)
                                       : StringInputBufferCompare(x, y);
 }
 
 
 static Object* Runtime_Math_acos(Arguments args) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 1);
   Counters::math_acos.Increment();
@@ skipping 4205 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal