diff --git a/src/array.js b/src/array.js
index 2a447d94ee..9fbc67cdce 100644
--- a/src/array.js
+++ b/src/array.js
@@ -90,7 +90,8 @@ function UseSparseVariant(array, length, is_array, touched) {
   // Only use the sparse variant on arrays that are likely to be sparse and the
   // number of elements touched in the operation is relatively small compared to
   // the overall size of the array.
-  if (!is_array || length < 1000 || %IsObserved(array)) {
+  if (!is_array || length < 1000 || %IsObserved(array) ||
+      %HasComplexElements(array)) {
     return false;
   }
   if (!%_IsSmi(length)) {
@@ -203,7 +204,7 @@ function ConvertToLocaleString(e) {
 
 // This function implements the optimized splice implementation that can use
 // special array operations to handle sparse arrays in a sensible fashion.
-function SmartSlice(array, start_i, del_count, len, deleted_elements) {
+function SparseSlice(array, start_i, del_count, len, deleted_elements) {
   // Move deleted elements to a new array (the return value from splice).
   var indices = %GetArrayKeys(array, start_i + del_count);
   if (IS_NUMBER(indices)) {
@@ -233,7 +234,7 @@ function SmartSlice(array, start_i, del_count, len, deleted_elements) {
 
 // This function implements the optimized splice implementation that can use
 // special array operations to handle sparse arrays in a sensible fashion.
-function SmartMove(array, start_i, del_count, len, num_additional_args) {
+function SparseMove(array, start_i, del_count, len, num_additional_args) {
   // Bail out if no moving is necessary.
   if (num_additional_args === del_count) return;
   // Move data to new array.
@@ -608,8 +609,8 @@ function ArrayShift() {
 
   var first = array[0];
 
-  if (IS_ARRAY(array)) {
-    SmartMove(array, 0, 1, len, 0);
+  if (UseSparseVariant(array, len, IS_ARRAY(array), len)) {
+    SparseMove(array, 0, 1, len, 0);
   } else {
     SimpleMove(array, 0, 1, len, 0);
   }
@@ -648,10 +649,10 @@ function ArrayUnshift(arg1) {  // length == 1
   var array = TO_OBJECT_INLINE(this);
   var len = TO_UINT32(array.length);
   var num_arguments = %_ArgumentsLength();
-  var is_sealed = ObjectIsSealed(array);
 
-  if (IS_ARRAY(array) && !is_sealed && len > 0) {
-    SmartMove(array, 0, 0, len, num_arguments);
+  if (len > 0 && UseSparseVariant(array, len, IS_ARRAY(array), len) &&
+     !ObjectIsSealed(array)) {
+    SparseMove(array, 0, 0, len, num_arguments);
   } else {
     SimpleMove(array, 0, 0, len, num_arguments);
   }
@@ -697,7 +698,7 @@ function ArraySlice(start, end) {
   if (UseSparseVariant(array, len, IS_ARRAY(array), end_i - start_i)) {
     %NormalizeElements(array);
     %NormalizeElements(result);
-    SmartSlice(array, start_i, end_i - start_i, len, result);
+    SparseSlice(array, start_i, end_i - start_i, len, result);
   } else {
     SimpleSlice(array, start_i, end_i - start_i, len, result);
   }
@@ -813,8 +814,8 @@ function ArraySplice(start, delete_count) {
   if (UseSparseVariant(array, len, IS_ARRAY(array), changed_elements)) {
     %NormalizeElements(array);
     %NormalizeElements(deleted_elements);
-    SmartSlice(array, start_i, del_count, len, deleted_elements);
-    SmartMove(array, start_i, del_count, len, num_elements_to_add);
+    SparseSlice(array, start_i, del_count, len, deleted_elements);
+    SparseMove(array, start_i, del_count, len, num_elements_to_add);
   } else {
     SimpleSlice(array, start_i, del_count, len, deleted_elements);
     SimpleMove(array, start_i, del_count, len, num_elements_to_add);
diff --git a/src/objects.cc b/src/objects.cc
index 5496b7e364..4359f17385 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -14212,9 +14212,11 @@ template
 int Dictionary<NameDictionary, NameDictionaryShape, Handle<Name> >::
     NumberOfEnumElements();
 
-template
-int HashTable<SeededNumberDictionary, SeededNumberDictionaryShape, uint32_t>::
-    FindEntry(uint32_t);
+template bool Dictionary<SeededNumberDictionary, SeededNumberDictionaryShape,
+                         uint32_t>::HasComplexElements();
+
+template int HashTable<SeededNumberDictionary, SeededNumberDictionaryShape,
+                       uint32_t>::FindEntry(uint32_t);
 
 
 Handle<Object> JSObject::PrepareSlowElementsForSort(
@@ -15262,10 +15264,26 @@ int Dictionary<Derived, Shape, Key>::NumberOfEnumElements() {
 }
 
 
-template<typename Derived, typename Shape, typename Key>
+template <typename Derived, typename Shape, typename Key>
+bool Dictionary<Derived, Shape, Key>::HasComplexElements() {
+  int capacity = DerivedHashTable::Capacity();
+  for (int i = 0; i < capacity; i++) {
+    Object* k = DerivedHashTable::KeyAt(i);
+    if (DerivedHashTable::IsKey(k) && !FilterKey(k, NONE)) {
+      PropertyDetails details = DetailsAt(i);
+      if (details.IsDeleted()) continue;
+      if (details.type() == CALLBACKS) return true;
+      PropertyAttributes attr = details.attributes();
+      if (attr & (READ_ONLY | DONT_DELETE)) return true;
+    }
+  }
+  return false;
+}
+
+
+template <typename Derived, typename Shape, typename Key>
 void Dictionary<Derived, Shape, Key>::CopyKeysTo(
-    FixedArray* storage,
-    PropertyAttributes filter,
+    FixedArray* storage, PropertyAttributes filter,
     typename Dictionary<Derived, Shape, Key>::SortMode sort_mode) {
   DCHECK(storage->length() >= NumberOfElementsFilterAttributes(filter));
   int capacity = DerivedHashTable::Capacity();
diff --git a/src/objects.h b/src/objects.h
index 6eb2697c6f..649111d00b 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -3550,6 +3550,10 @@ class Dictionary: public HashTable<Derived, Shape, Key> {
   // Returns the number of enumerable elements in the dictionary.
   int NumberOfEnumElements();
 
+  // Returns true if the dictionary contains any elements that are non-writable,
+  // non-configurable, or have getters/setters.
+  bool HasComplexElements();
+
   enum SortMode { UNSORTED, SORTED };
   // Copies keys to preallocated fixed array.
   void CopyKeysTo(FixedArray* storage,
diff --git a/src/runtime/runtime-array.cc b/src/runtime/runtime-array.cc
index 5a6bba424b..c3a6d80ecf 100644
--- a/src/runtime/runtime-array.cc
+++ b/src/runtime/runtime-array.cc
@@ -1043,6 +1043,30 @@ RUNTIME_FUNCTION(Runtime_NormalizeElements) {
 }
 
 
+RUNTIME_FUNCTION(Runtime_HasComplexElements) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_ARG_HANDLE_CHECKED(JSObject, array, 0);
+  for (PrototypeIterator iter(isolate, array,
+                              PrototypeIterator::START_AT_RECEIVER);
+       !iter.IsAtEnd(); iter.Advance()) {
+    if (PrototypeIterator::GetCurrent(iter)->IsJSProxy()) {
+      return isolate->heap()->true_value();
+    }
+    Handle<JSObject> current =
+        Handle<JSObject>::cast(PrototypeIterator::GetCurrent(iter));
+    if (current->HasIndexedInterceptor()) {
+      return isolate->heap()->true_value();
+    }
+    if (!current->HasDictionaryElements()) continue;
+    if (current->element_dictionary()->HasComplexElements()) {
+      return isolate->heap()->true_value();
+    }
+  }
+  return isolate->heap()->false_value();
+}
+
+
 // TODO(dcarney): remove this function when TurboFan supports it.
 // Takes the object to be iterated over and the result of GetPropertyNamesFast
 // Returns pair (cache_array, cache_type).
diff --git a/src/runtime/runtime.h b/src/runtime/runtime.h
index 02174392c9..657a17db5d 100644
--- a/src/runtime/runtime.h
+++ b/src/runtime/runtime.h
@@ -268,6 +268,7 @@ namespace internal {
   F(MoveArrayContents, 2, 1)                           \
   F(EstimateNumberOfElements, 1, 1)                    \
   F(NormalizeElements, 1, 1)                           \
+  F(HasComplexElements, 1, 1)                          \
                                                        \
   /* Getters and Setters */                            \
   F(LookupAccessor, 3, 1)                              \
diff --git a/test/mjsunit/array-natives-elements.js b/test/mjsunit/array-natives-elements.js
index d63346d0a4..e567e7f480 100644
--- a/test/mjsunit/array-natives-elements.js
+++ b/test/mjsunit/array-natives-elements.js
@@ -280,8 +280,7 @@ function array_natives_test() {
   assertEquals([1.1,1,2,3], a4);
   a4 = [1.1,2,3];
   a4.unshift(1);
-  // assertTrue(%HasFastDoubleElements(a4));
-  assertTrue(%HasFastObjectElements(a4));
+  assertTrue(%HasFastDoubleElements(a4));
   assertEquals([1,1.1,2,3], a4);
   a4 = [{},2,3];
   a4.unshift(1);
diff --git a/test/mjsunit/array-shift2.js b/test/mjsunit/array-shift2.js
index 73d8cd4ff1..75233ffec2 100644
--- a/test/mjsunit/array-shift2.js
+++ b/test/mjsunit/array-shift2.js
@@ -12,7 +12,17 @@ function test(array) {
   array.shift();
   return array;
 }
-assertEquals(["element 1",2], test(["0",,2]));
-assertEquals(["element 1",{}], test([{},,{}]));
+
+var result = test(["0",,2]);
+assertEquals(["element 1","element 1"], result);
+assertTrue(result.hasOwnProperty("0"));
+assertFalse(result.hasOwnProperty("1"));
+result = test([{},,{}]);
+assertEquals(["element 1","element 1"], result);
+assertTrue(result.hasOwnProperty("0"));
+assertFalse(result.hasOwnProperty("1"));
 %OptimizeFunctionOnNextCall(test);
-assertEquals(["element 1",0], test([{},,0]));
+result = test([{},,0]);
+assertEquals(["element 1","element 1"], result);
+assertTrue(result.hasOwnProperty("0"));
+assertFalse(result.hasOwnProperty("1"));
diff --git a/test/mjsunit/bugs/bug-2615.js b/test/mjsunit/bugs/bug-2615.js
index 51aeaf4924..5da17eecf1 100644
--- a/test/mjsunit/bugs/bug-2615.js
+++ b/test/mjsunit/bugs/bug-2615.js
@@ -38,89 +38,3 @@ assertThrows("a.splice(1,1,7,7,7,7,7);", RangeError);
 assertEquals([1,7,7,7,7,7,3], a.slice(0, 7));
 assertEquals(0xffffffff, a.length);
 assertEquals(10, a[0xfffffffe + 5 - 1]);
-
-a = [1];
-Object.defineProperty(a, "1", {writable:false, configurable:false, value: 100});
-assertThrows("a.unshift(4);", TypeError);
-assertEquals([1, 100, 100], a);
-var desc = Object.getOwnPropertyDescriptor(a, "1");
-assertEquals(false, desc.writable);
-assertEquals(false, desc.configurable);
-
-a = [1];
-var g = function() { return 100; };
-Object.defineProperty(a, "1", {get:g});
-assertThrows("a.unshift(0);", TypeError);
-assertEquals([1, 100, 100], a);
-desc = Object.getOwnPropertyDescriptor(a, "1");
-assertEquals(false, desc.configurable);
-assertEquals(g, desc.get);
-
-a = [1];
-var c = 0;
-var s = function(v) { c += 1; };
-Object.defineProperty(a, "1", {set:s});
-a.unshift(10);
-assertEquals([10, undefined, undefined], a);
-assertEquals(1, c);
-desc = Object.getOwnPropertyDescriptor(a, "1");
-assertEquals(false, desc.configurable);
-assertEquals(s, desc.set);
-
-a = [1];
-Object.defineProperty(a, "1", {configurable:false, value:10});
-assertThrows("a.splice(1,1);", TypeError);
-assertEquals([1, 10], a);
-desc = Object.getOwnPropertyDescriptor(a, "1");
-assertEquals(false, desc.configurable);
-
-a = [0,1,2,3,4,5,6];
-Object.defineProperty(a, "3", {configurable:false, writable:false, value:3});
-assertThrows("a.splice(1,4);", TypeError);
-assertEquals([0,5,6,3,,,,,], a);
-desc = Object.getOwnPropertyDescriptor(a, "3");
-assertEquals(false, desc.configurable);
-assertEquals(false, desc.writable);
-
-a = [0,1,2,3,4,5,6];
-Object.defineProperty(a, "5", {configurable:false, value:5});
-assertThrows("a.splice(1,4);", TypeError);
-assertEquals([0,5,6,3,4,5,,,], a);
-desc = Object.getOwnPropertyDescriptor(a, "5");
-assertEquals(false, desc.configurable);
-
-a = [1,2,3,,5];
-Object.defineProperty(a, "1", {configurable:false, writable:true, value:2});
-assertEquals(1, a.shift());
-assertEquals([2,3,,5], a);
-desc = Object.getOwnPropertyDescriptor(a, "1");
-assertEquals(false, desc.configurable);
-assertEquals(true, desc.writable);
-assertThrows("a.shift();", TypeError);
-assertEquals([3,3,,5], a);
-desc = Object.getOwnPropertyDescriptor(a, "1");
-assertEquals(false, desc.configurable);
-assertEquals(true, desc.writable);
-
-a = [1,2,3];
-Object.defineProperty(a, "2", {configurable:false, value:3});
-assertThrows("a.pop();", TypeError);
-assertEquals([1,2,3], a);
-desc = Object.getOwnPropertyDescriptor(a, "2");
-assertEquals(false, desc.configurable);
-
-a = [1,2,,,5];
-Object.defineProperty(a, "4", {writable:true, configurable:false, value:5});
-assertThrows("a.sort();", TypeError);
-assertEquals([1,2,5,,5], a);
-desc = Object.getOwnPropertyDescriptor(a, "2");
-assertEquals(true, desc.configurable);
-desc = Object.getOwnPropertyDescriptor(a, "4");
-assertEquals(false, desc.configurable);
-
-a = [1,2,3,,5,6];
-Object.defineProperty(a, "4", {value:5, writable:false});
-assertThrows("a.sort();", TypeError);
-assertEquals([1,2,3,5,5,6], a);
-desc = Object.getOwnPropertyDescriptor(a, "4");
-assertEquals(false, desc.writable);
diff --git a/test/mjsunit/regress/regress-2615.js b/test/mjsunit/regress/regress-2615.js
new file mode 100644
index 0000000000..6b277e8765
--- /dev/null
+++ b/test/mjsunit/regress/regress-2615.js
@@ -0,0 +1,96 @@
+// Copyright 2013 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
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+a = [1];
+Object.defineProperty(a, "1", {writable:false, configurable:false, value: 100});
+assertThrows("a.unshift(4);", TypeError);
+assertEquals([1, 100, 100], a);
+var desc = Object.getOwnPropertyDescriptor(a, "1");
+assertEquals(false, desc.writable);
+assertEquals(false, desc.configurable);
+
+a = [1];
+var g = function() { return 100; };
+Object.defineProperty(a, "1", {get:g});
+assertThrows("a.unshift(0);", TypeError);
+assertEquals([1, 100, 100], a);
+desc = Object.getOwnPropertyDescriptor(a, "1");
+assertEquals(false, desc.configurable);
+assertEquals(g, desc.get);
+
+a = [1];
+var c = 0;
+var s = function(v) { c += 1; };
+Object.defineProperty(a, "1", {set:s});
+a.unshift(10);
+assertEquals([10, undefined, undefined], a);
+assertEquals(1, c);
+desc = Object.getOwnPropertyDescriptor(a, "1");
+assertEquals(false, desc.configurable);
+assertEquals(s, desc.set);
+
+a = [1];
+Object.defineProperty(a, "1", {configurable:false, value:10});
+assertThrows("a.splice(1,1);", TypeError);
+assertEquals([1, 10], a);
+desc = Object.getOwnPropertyDescriptor(a, "1");
+assertEquals(false, desc.configurable);
+
+a = [0,1,2,3,4,5,6];
+Object.defineProperty(a, "3", {configurable:false, writable:false, value:3});
+assertThrows("a.splice(1,4);", TypeError);
+assertEquals([0,5,6,3,,,,], a);
+desc = Object.getOwnPropertyDescriptor(a, "3");
+assertEquals(false, desc.configurable);
+assertEquals(false, desc.writable);
+
+a = [0,1,2,3,4,5,6];
+Object.defineProperty(a, "5", {configurable:false, value:5});
+assertThrows("a.splice(1,4);", TypeError);
+assertEquals([0,5,6,3,4,5,,], a);
+desc = Object.getOwnPropertyDescriptor(a, "5");
+assertEquals(false, desc.configurable);
+
+a = [1,2,3,,5];
+Object.defineProperty(a, "1", {configurable:false, writable:true, value:2});
+assertEquals(1, a.shift());
+assertEquals([2,3,,5], a);
+desc = Object.getOwnPropertyDescriptor(a, "1");
+assertEquals(false, desc.configurable);
+assertEquals(true, desc.writable);
+assertThrows("a.shift();", TypeError);
+assertEquals([3,3,,5], a);
+desc = Object.getOwnPropertyDescriptor(a, "1");
+assertEquals(false, desc.configurable);
+assertEquals(true, desc.writable);
+
+a = [1,2,3];
+Object.defineProperty(a, "2", {configurable:false, value:3});
+assertThrows("a.pop();", TypeError);
+assertEquals([1,2,3], a);
+desc = Object.getOwnPropertyDescriptor(a, "2");
+assertEquals(false, desc.configurable);
diff --git a/test/mjsunit/bugs/bug-3612.js b/test/mjsunit/regress/regress-3612.js
similarity index 100%
rename from test/mjsunit/bugs/bug-3612.js
rename to test/mjsunit/regress/regress-3612.js
diff --git a/test/mjsunit/bugs/bug-3621.js b/test/mjsunit/regress/regress-3621.js
similarity index 100%
rename from test/mjsunit/bugs/bug-3621.js
rename to test/mjsunit/regress/regress-3621.js
diff --git a/test/mjsunit/regress/regress-crbug-412319.js b/test/mjsunit/regress/regress-crbug-412319.js
index 21386e3bd6..c597b0dd87 100644
--- a/test/mjsunit/regress/regress-crbug-412319.js
+++ b/test/mjsunit/regress/regress-crbug-412319.js
@@ -15,5 +15,5 @@ __f_6();
 %OptimizeFunctionOnNextCall(__f_6);
 __f_6();
 function __f_7(__v_7) {
-  __v_7.push(Infinity);
+  __v_7.pop();
 }
diff --git a/test/mozilla/mozilla.status b/test/mozilla/mozilla.status
index e9f58c6133..00ba050bb4 100644
--- a/test/mozilla/mozilla.status
+++ b/test/mozilla/mozilla.status
@@ -117,6 +117,11 @@
   'js1_5/GC/regress-348532': [SKIP],
 
 
+  # Runs for too long: huge array with getters and setters. As it says
+  # in the test: "This test will probably run out of memory".
+  'js1_5/extensions/regress-345967': [SKIP],
+
+
   ##################### FLAKY TESTS #####################
 
   # These tests time out in debug mode but pass in product mode
@@ -674,7 +679,6 @@
   'js1_5/extensions/regress-311792-01': [FAIL_OK],
   'js1_5/extensions/regress-312278': [FAIL_OK],
   'js1_5/extensions/regress-313630': [FAIL_OK],
-  'js1_5/extensions/regress-313763': [FAIL_OK],
   'js1_5/extensions/regress-313803': [FAIL_OK],
   'js1_5/extensions/regress-314874': [FAIL_OK],
   'js1_5/extensions/regress-322957': [FAIL_OK],
@@ -684,8 +688,6 @@
   'js1_5/extensions/regress-336409-1': [FAIL_OK],
   'js1_5/extensions/regress-336409-2': [FAIL_OK],
   'js1_5/extensions/regress-336410-2': [FAIL_OK],
-  'js1_5/extensions/regress-341956-01': [FAIL_OK],
-  'js1_5/extensions/regress-345967': [FAIL_OK],
   'js1_5/extensions/regress-346494-01': [FAIL_OK],
   'js1_5/extensions/regress-346494': [FAIL_OK],
   'js1_5/extensions/regress-347306-02': [FAIL_OK],