A bug in AllocationSite::GetMode(from, to) meant that we didn't update

test/mjsunit/allocation-site-info.js

 // Copyright 2012 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 157 matching lines @@
     return literal;
   }
 
   obj = fastliteralcase_smifast(1);
   assertKind(elements_kind.fast_smi_only, obj);
   obj = fastliteralcase_smifast("carter");
   assertKind(elements_kind.fast, obj);
   obj = fastliteralcase_smifast(2);
   assertKind(elements_kind.fast, obj);
 
+  // Case: make sure transitions from packed to holey are tracked
+  function fastliteralcase_smiholey(index, value) {
+    var literal = [1, 2, 3, 4];
+    literal[index] = value;
+    return literal;
+  }
+
+  obj = fastliteralcase_smiholey(5, 1);
+  assertKind(elements_kind.fast_smi_only, obj);
+  assertHoley(obj);
+  obj = fastliteralcase_smiholey(0, 1);
+  assertKind(elements_kind.fast_smi_only, obj);
+  assertHoley(obj);
+
   function newarraycase_smidouble(value) {
     var a = new Array();
     a[0] = value;
     return a;
   }
 
   // Case: new Array() as allocation site, smi->double
   obj = newarraycase_smidouble(1);
   assertKind(elements_kind.fast_smi_only, obj);
   obj = newarraycase_smidouble(1.5);
@@ skipping 145 matching lines @@
   %ClearFunctionTypeFeedback(instanceof_check);
   instanceof_check(Array);
   instanceof_check(Array);
   %OptimizeFunctionOnNextCall(instanceof_check);
   instanceof_check(Array);
   assertTrue(2 != %GetOptimizationStatus(instanceof_check));
 
   instanceof_check(realmBArray);
   assertTrue(1 != %GetOptimizationStatus(instanceof_check));
 }