* Added check for HeapNumber in the fast-cast Smi switch.

src/runtime.cc

 // Copyright 2006-2008 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 2536 matching lines @@
   NoHandleAllocation ha;
   ASSERT(args.length() == 1);
 
   Object* obj = args[0];
   if (obj->IsSmi()) return obj;
   CONVERT_DOUBLE_CHECKED(number, obj);
   return Heap::NumberFromInt32(DoubleToInt32(number));
 }
 
 
+// Converts a Number to a Smi, if possible. Returns NaN if the number is not
+// a small integer.
+static Object* Runtime_NumberToSmi(Arguments args) {
+  NoHandleAllocation ha;
+  ASSERT(args.length() == 1);
+
+  Object* obj = args[0];
+  if (obj->IsSmi()) {
+    return obj;
+  }
+  if (obj->IsHeapNumber()) {
+    double value = HeapNumber::cast(obj)->value();
+    int int_value = FastD2I(value);
+    if (value == FastI2D(int_value) && Smi::IsValid(int_value)) {
+      return Smi::FromInt(int_value);
+    }
+  }
+  return Heap::nan_value();
+}
+
 static Object* Runtime_NumberAdd(Arguments args) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 2);
 
   CONVERT_DOUBLE_CHECKED(x, args[0]);
   CONVERT_DOUBLE_CHECKED(y, args[1]);
   return Heap::AllocateHeapNumber(x + y);
 }
 
 
@@ skipping 3236 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();
   }
 }
 
 
 } }  // namespace v8::internal