[turbofan] Enable Array.p.reduce[Right] for holey arrays

Change-Id: If1a3d08c1fca73234d94db6b527f5d11d10aa6cc
Reviewed-on: https://chromium-review.googlesource.com/867032
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50722}

src/compiler/js-call-reducer.cc

@@ -997,255 +997,21 @@ Reduction JSCallReducer::ReduceArrayForEach(Handle<JSFunction> function,
   ReplaceWithValue(node, jsgraph()->UndefinedConstant(), effect, control);
   return Replace(jsgraph()->UndefinedConstant());
 }
-
 Reduction JSCallReducer::ReduceArrayReduce(Handle<JSFunction> function,
-                                           Node* node) {
+                                           Node* node,
+                                           ArrayReduceDirection direction) {
   if (!FLAG_turbo_inline_array_builtins) return NoChange();
   DCHECK_EQ(IrOpcode::kJSCall, node->opcode());
-
-  Node* outer_frame_state = NodeProperties::GetFrameStateInput(node);
-  Node* effect = NodeProperties::GetEffectInput(node);
-  Node* control = NodeProperties::GetControlInput(node);
-  Node* context = NodeProperties::GetContextInput(node);
   CallParameters const& p = CallParametersOf(node->op());
   if (p.speculation_mode() == SpeculationMode::kDisallowSpeculation) {
     return NoChange();
   }
-
-  // Try to determine the {receiver} map.
-  Node* receiver = NodeProperties::GetValueInput(node, 1);
-  Node* fncallback = node->op()->ValueInputCount() > 2
-                         ? NodeProperties::GetValueInput(node, 2)
-                         : jsgraph()->UndefinedConstant();
-
-  ZoneHandleSet<Map> receiver_maps;
-  NodeProperties::InferReceiverMapsResult result =
-      NodeProperties::InferReceiverMaps(receiver, effect, &receiver_maps);
-  if (result == NodeProperties::kNoReceiverMaps) return NoChange();
-
-  ElementsKind kind = IsDoubleElementsKind(receiver_maps[0]->elements_kind())
-                          ? PACKED_DOUBLE_ELEMENTS
-                          : PACKED_ELEMENTS;
-  for (Handle<Map> receiver_map : receiver_maps) {
-    ElementsKind next_kind = receiver_map->elements_kind();
-    if (!CanInlineArrayIteratingBuiltin(receiver_map)) {
-      return NoChange();
-    }
-    if (!IsFastElementsKind(next_kind) || IsHoleyElementsKind(next_kind)) {
-      return NoChange();
-    }
-    if (IsDoubleElementsKind(kind) != IsDoubleElementsKind(next_kind)) {
-      return NoChange();
-    }
-    if (IsHoleyElementsKind(next_kind)) {
-      kind = HOLEY_ELEMENTS;
-    }
-  }
-
-  // Install code dependencies on the {receiver} prototype maps and the
-  // global array protector cell.
-  dependencies()->AssumePropertyCell(factory()->no_elements_protector());
-
-  // If we have unreliable maps, we need a map check.
-  if (result == NodeProperties::kUnreliableReceiverMaps) {
-    effect =
-        graph()->NewNode(simplified()->CheckMaps(CheckMapsFlag::kNone,
-                                                 receiver_maps, p.feedback()),
-                         receiver, effect, control);
-  }
-
-  Node* original_length = effect = graph()->NewNode(
-      simplified()->LoadField(AccessBuilder::ForJSArrayLength(PACKED_ELEMENTS)),
-      receiver, effect, control);
-
-  Node* k = jsgraph()->ZeroConstant();
-
-  std::vector<Node*> checkpoint_params({receiver, fncallback, k,
-                                        original_length,
-                                        jsgraph()->UndefinedConstant()});
-  const int stack_parameters = static_cast<int>(checkpoint_params.size());
-
-  // Check whether the given callback function is callable. Note that this has
-  // to happen outside the loop to make sure we also throw on empty arrays.
-  Node* check_frame_state = CreateJavaScriptBuiltinContinuationFrameState(
-      jsgraph(), function, Builtins::kArrayReduceLoopLazyDeoptContinuation,
-      node->InputAt(0), context, &checkpoint_params[0], stack_parameters - 1,
-      outer_frame_state, ContinuationFrameStateMode::LAZY);
-  Node* check_fail = nullptr;
-  Node* check_throw = nullptr;
-  WireInCallbackIsCallableCheck(fncallback, context, check_frame_state, effect,
-                                &control, &check_fail, &check_throw);
-
-  // Set initial accumulator value
-  Node* cur = jsgraph()->TheHoleConstant();
-
-  Node* initial_element_check_fail = nullptr;
-  Node* initial_element_check_throw = nullptr;
-  if (node->op()->ValueInputCount() > 3) {
-    cur = NodeProperties::GetValueInput(node, 3);
-  } else {
-    Node* check =
-        graph()->NewNode(simplified()->NumberEqual(), original_length, k);
-    Node* check_branch =
-        graph()->NewNode(common()->Branch(BranchHint::kFalse), check, control);
-    initial_element_check_fail =
-        graph()->NewNode(common()->IfTrue(), check_branch);
-    initial_element_check_throw = graph()->NewNode(
-        javascript()->CallRuntime(Runtime::kThrowTypeError, 2),
-        jsgraph()->Constant(MessageTemplate::kReduceNoInitial), fncallback,
-        context, check_frame_state, effect, initial_element_check_fail);
-    control = graph()->NewNode(common()->IfFalse(), check_branch);
-
-    cur = SafeLoadElement(kind, receiver, control, &effect, &k, p.feedback());
-    k = graph()->NewNode(simplified()->NumberAdd(), k,
-                         jsgraph()->OneConstant());
-  }
-
-  // Start the loop.
-  Node* loop = control = graph()->NewNode(common()->Loop(2), control, control);
-  Node* eloop = effect =
-      graph()->NewNode(common()->EffectPhi(2), effect, effect, loop);
-  Node* terminate = graph()->NewNode(common()->Terminate(), eloop, loop);
-  NodeProperties::MergeControlToEnd(graph(), common(), terminate);
-  Node* kloop = k = graph()->NewNode(
-      common()->Phi(MachineRepresentation::kTagged, 2), k, k, loop);
-  Node* curloop = cur = graph()->NewNode(
-      common()->Phi(MachineRepresentation::kTagged, 2), cur, cur, loop);
-  checkpoint_params[2] = k;
-  checkpoint_params[4] = curloop;
-
-  control = loop;
-  effect = eloop;
-
-  Node* continue_test =
-      graph()->NewNode(simplified()->NumberLessThan(), k, original_length);
-  Node* continue_branch = graph()->NewNode(common()->Branch(BranchHint::kTrue),
-                                           continue_test, control);
-
-  Node* if_true = graph()->NewNode(common()->IfTrue(), continue_branch);
-  Node* if_false = graph()->NewNode(common()->IfFalse(), continue_branch);
-  control = if_true;
-
-  Node* frame_state = CreateJavaScriptBuiltinContinuationFrameState(
-      jsgraph(), function, Builtins::kArrayReduceLoopEagerDeoptContinuation,
-      node->InputAt(0), context, &checkpoint_params[0], stack_parameters,
-      outer_frame_state, ContinuationFrameStateMode::EAGER);
-
-  effect =
-      graph()->NewNode(common()->Checkpoint(), frame_state, effect, control);
-
-  // Make sure the map hasn't changed during the iteration
-  effect = graph()->NewNode(
-      simplified()->CheckMaps(CheckMapsFlag::kNone, receiver_maps), receiver,
-      effect, control);
-
-  Node* element =
-      SafeLoadElement(kind, receiver, control, &effect, &k, p.feedback());
-
-  Node* next_k =
-      graph()->NewNode(simplified()->NumberAdd(), k, jsgraph()->OneConstant());
-  checkpoint_params[2] = next_k;
-
-  Node* hole_true = nullptr;
-  Node* hole_false = nullptr;
-  Node* effect_true = effect;
-
-  if (IsHoleyElementsKind(kind)) {
-    // Holey elements kind require a hole check and skipping of the element in
-    // the case of a hole.
-    Node* check = graph()->NewNode(simplified()->ReferenceEqual(), element,
-                                   jsgraph()->TheHoleConstant());
-    Node* branch =
-        graph()->NewNode(common()->Branch(BranchHint::kFalse), check, control);
-    hole_true = graph()->NewNode(common()->IfTrue(), branch);
-    hole_false = graph()->NewNode(common()->IfFalse(), branch);
-    control = hole_false;
-
-    // The contract is that we don't leak "the hole" into "user JavaScript",
-    // so we must rename the {element} here to explicitly exclude "the hole"
-    // from the type of {element}.
-    element = effect = graph()->NewNode(
-        common()->TypeGuard(Type::NonInternal()), element, effect, control);
-  }
-
-  frame_state = CreateJavaScriptBuiltinContinuationFrameState(
-      jsgraph(), function, Builtins::kArrayReduceLoopLazyDeoptContinuation,
-      node->InputAt(0), context, &checkpoint_params[0], stack_parameters - 1,
-      outer_frame_state, ContinuationFrameStateMode::LAZY);
-
-  Node* next_cur = control = effect =
-      graph()->NewNode(javascript()->Call(6, p.frequency()), fncallback,
-                       jsgraph()->UndefinedConstant(), cur, element, k,
-                       receiver, context, frame_state, effect, control);
-
-  // Rewire potential exception edges.
-  Node* on_exception = nullptr;
-  if (NodeProperties::IsExceptionalCall(node, &on_exception)) {
-    RewirePostCallbackExceptionEdges(check_throw, on_exception, effect,
-                                     &check_fail, &control);
-  }
-
-  if (IsHoleyElementsKind(kind)) {
-    Node* after_call_control = control;
-    Node* after_call_effect = effect;
-    control = hole_true;
-    effect = effect_true;
-
-    control = graph()->NewNode(common()->Merge(2), control, after_call_control);
-    effect = graph()->NewNode(common()->EffectPhi(2), effect, after_call_effect,
-                              control);
-    next_cur =
-        graph()->NewNode(common()->Phi(MachineRepresentation::kTagged, 2), cur,
-                         next_cur, control);
-  }
-
-  k = next_k;
-  cur = next_cur;
-
-  loop->ReplaceInput(1, control);
-  kloop->ReplaceInput(1, k);
-  curloop->ReplaceInput(1, cur);
-  eloop->ReplaceInput(1, effect);
-
-  control = if_false;
-  effect = eloop;
-
-  // Wire up the branch for the case when IsCallable fails for the callback.
-  // Since {check_throw} is an unconditional throw, it's impossible to
-  // return a successful completion. Therefore, we simply connect the successful
-  // completion to the graph end.
-  Node* throw_node =
-      graph()->NewNode(common()->Throw(), check_throw, check_fail);
-  NodeProperties::MergeControlToEnd(graph(), common(), throw_node);
-
-  if (node->op()->ValueInputCount() <= 3) {
-    // Wire up the branch for the case when an array is empty.
-    // Since {check_throw} is an unconditional throw, it's impossible to
-    // return a successful completion. Therefore, we simply connect the
-    // successful completion to the graph end.
-    Node* throw_node =
-        graph()->NewNode(common()->Throw(), initial_element_check_throw,
-                         initial_element_check_fail);
-    NodeProperties::MergeControlToEnd(graph(), common(), throw_node);
-  }
-
-  ReplaceWithValue(node, curloop, effect, control);
-  return Replace(curloop);
-}  // namespace compiler
-
-Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
-                                                Node* node) {
-  if (!FLAG_turbo_inline_array_builtins) return NoChange();
-  DCHECK_EQ(IrOpcode::kJSCall, node->opcode());
+  bool left = direction == ArrayReduceDirection::kArrayReduceLeft;
 
   Node* outer_frame_state = NodeProperties::GetFrameStateInput(node);
   Node* effect = NodeProperties::GetEffectInput(node);
   Node* control = NodeProperties::GetControlInput(node);
   Node* context = NodeProperties::GetContextInput(node);
-  CallParameters const& p = CallParametersOf(node->op());
-  if (p.speculation_mode() == SpeculationMode::kDisallowSpeculation) {
-    return NoChange();
-  }
 
   // Try to determine the {receiver} map.
   Node* receiver = NodeProperties::GetValueInput(node, 1);
@@ -1263,10 +1029,8 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
                           : PACKED_ELEMENTS;
   for (Handle<Map> receiver_map : receiver_maps) {
     ElementsKind next_kind = receiver_map->elements_kind();
-    if (!CanInlineArrayIteratingBuiltin(receiver_map)) {
-      return NoChange();
-    }
-    if (!IsFastElementsKind(next_kind) || IsHoleyElementsKind(next_kind)) {
+    if (!CanInlineArrayIteratingBuiltin(receiver_map)) return NoChange();
+    if (!IsFastElementsKind(next_kind) || next_kind == HOLEY_DOUBLE_ELEMENTS) {
       return NoChange();
     }
     if (IsDoubleElementsKind(kind) != IsDoubleElementsKind(next_kind)) {
@@ -1293,48 +1057,68 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
       simplified()->LoadField(AccessBuilder::ForJSArrayLength(PACKED_ELEMENTS)),
       receiver, effect, control);
 
-  Node* k = graph()->NewNode(simplified()->NumberSubtract(), original_length,
-                             jsgraph()->OneConstant());
+  Node* initial_index =
+      left ? jsgraph()->ZeroConstant()
+           : graph()->NewNode(simplified()->NumberSubtract(), original_length,
+                              jsgraph()->OneConstant());
+  const Operator* next_op =
+      left ? simplified()->NumberAdd() : simplified()->NumberSubtract();
+  Node* k = initial_index;
 
   std::vector<Node*> checkpoint_params({receiver, fncallback, k,
                                         original_length,
                                         jsgraph()->UndefinedConstant()});
   const int stack_parameters = static_cast<int>(checkpoint_params.size());
 
-  // Check whether the given callback function is callable. Note that this has
-  // to happen outside the loop to make sure we also throw on empty arrays.
+  Builtins::Name builtin =
+      left ? Builtins::kArrayReduceLoopLazyDeoptContinuation
+           : Builtins::kArrayReduceRightLoopLazyDeoptContinuation;
+
+  // Check whether the given callback function is callable. Note that
+  // this has to happen outside the loop to make sure we also throw on
+  // empty arrays.
   Node* check_frame_state = CreateJavaScriptBuiltinContinuationFrameState(
-      jsgraph(), function, Builtins::kArrayReduceRightLoopLazyDeoptContinuation,
-      node->InputAt(0), context, &checkpoint_params[0], stack_parameters - 1,
-      outer_frame_state, ContinuationFrameStateMode::LAZY);
+      jsgraph(), function, builtin, node->InputAt(0), context,
+      &checkpoint_params[0], stack_parameters - 1, outer_frame_state,
+      ContinuationFrameStateMode::LAZY);
   Node* check_fail = nullptr;
   Node* check_throw = nullptr;
   WireInCallbackIsCallableCheck(fncallback, context, check_frame_state, effect,
                                 &control, &check_fail, &check_throw);
 
   // Set initial accumulator value
-  Node* cur = nullptr;
+  Node* cur = jsgraph()->TheHoleConstant();
 
-  Node* initial_element_check_fail = nullptr;
-  Node* initial_element_check_throw = nullptr;
   if (node->op()->ValueInputCount() > 3) {
     cur = NodeProperties::GetValueInput(node, 3);
   } else {
-    Node* check = graph()->NewNode(simplified()->NumberEqual(), original_length,
-                                   jsgraph()->SmiConstant(0));
-    Node* check_branch =
-        graph()->NewNode(common()->Branch(BranchHint::kFalse), check, control);
-    initial_element_check_fail =
-        graph()->NewNode(common()->IfTrue(), check_branch);
-    initial_element_check_throw = graph()->NewNode(
-        javascript()->CallRuntime(Runtime::kThrowTypeError, 2),
-        jsgraph()->Constant(MessageTemplate::kReduceNoInitial), fncallback,
-        context, check_frame_state, effect, initial_element_check_fail);
-    control = graph()->NewNode(common()->IfFalse(), check_branch);
+    // Find first/last non holey element.
+    Node* vloop = k = WireInLoopStart(k, &control, &effect);
+    Node* next_k = graph()->NewNode(next_op, k, jsgraph()->OneConstant());
+    Node* loop = control;
+    Node* eloop = effect;
+    effect = graph()->NewNode(common()->Checkpoint(), check_frame_state, effect,
+                              control);
+    Node* continue_test =
+        left ? graph()->NewNode(simplified()->NumberLessThan(), k,
+                                original_length)
+             : graph()->NewNode(simplified()->NumberLessThanOrEqual(),
+                                jsgraph()->ZeroConstant(), k);
+    effect = graph()->NewNode(simplified()->CheckIf(DeoptimizeReason::kUnknown),
+                              continue_test, effect, control);
 
     cur = SafeLoadElement(kind, receiver, control, &effect, &k, p.feedback());
-    k = graph()->NewNode(simplified()->NumberSubtract(), k,
-                         jsgraph()->OneConstant());
+
+    Node* hole_test = graph()->NewNode(simplified()->ReferenceEqual(), cur,
+                                       jsgraph()->TheHoleConstant());
+    Node* hole_branch = graph()->NewNode(common()->Branch(BranchHint::kTrue),
+                                         hole_test, control);
+    Node* found_el = graph()->NewNode(common()->IfFalse(), hole_branch);
+    control = found_el;
+    Node* is_hole = graph()->NewNode(common()->IfTrue(), hole_branch);
+
+    WireInLoopEnd(loop, eloop, vloop, next_k, is_hole, effect);
+    k = next_k;
   }
 
   // Start the loop.
@@ -1353,8 +1137,12 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
   control = loop;
   effect = eloop;
 
-  Node* continue_test = graph()->NewNode(simplified()->NumberLessThanOrEqual(),
-                                         jsgraph()->ZeroConstant(), k);
+  Node* continue_test =
+      left
+          ? graph()->NewNode(simplified()->NumberLessThan(), k, original_length)
+          : graph()->NewNode(simplified()->NumberLessThanOrEqual(),
+                             jsgraph()->ZeroConstant(), k);
+
   Node* continue_branch = graph()->NewNode(common()->Branch(BranchHint::kTrue),
                                            continue_test, control);
 
@@ -1363,9 +1151,8 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
   control = if_true;
 
   Node* frame_state = CreateJavaScriptBuiltinContinuationFrameState(
-      jsgraph(), function,
-      Builtins::kArrayReduceRightLoopEagerDeoptContinuation, node->InputAt(0),
-      context, &checkpoint_params[0], stack_parameters, outer_frame_state,
+      jsgraph(), function, builtin, node->InputAt(0), context,
+      &checkpoint_params[0], stack_parameters, outer_frame_state,
       ContinuationFrameStateMode::EAGER);
 
   effect =
@@ -1379,8 +1166,7 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
   Node* element =
       SafeLoadElement(kind, receiver, control, &effect, &k, p.feedback());
 
-  Node* next_k = graph()->NewNode(simplified()->NumberSubtract(), k,
-                                  jsgraph()->OneConstant());
+  Node* next_k = graph()->NewNode(next_op, k, jsgraph()->OneConstant());
   checkpoint_params[2] = next_k;
 
   Node* hole_true = nullptr;
@@ -1406,9 +1192,9 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
   }
 
   frame_state = CreateJavaScriptBuiltinContinuationFrameState(
-      jsgraph(), function, Builtins::kArrayReduceRightLoopLazyDeoptContinuation,
-      node->InputAt(0), context, &checkpoint_params[0], stack_parameters - 1,
-      outer_frame_state, ContinuationFrameStateMode::LAZY);
+      jsgraph(), function, builtin, node->InputAt(0), context,
+      &checkpoint_params[0], stack_parameters - 1, outer_frame_state,
+      ContinuationFrameStateMode::LAZY);
 
   Node* next_cur = control = effect =
       graph()->NewNode(javascript()->Call(6, p.frequency()), fncallback,
@@ -1455,20 +1241,9 @@ Reduction JSCallReducer::ReduceArrayReduceRight(Handle<JSFunction> function,
       graph()->NewNode(common()->Throw(), check_throw, check_fail);
   NodeProperties::MergeControlToEnd(graph(), common(), throw_node);
 
-  if (node->op()->ValueInputCount() <= 3) {
-    // Wire up the branch for the case when an array is empty.
-    // Since {check_throw} is an unconditional throw, it's impossible to
-    // return a successful completion. Therefore, we simply connect the
-    // successful completion to the graph end.
-    Node* throw_node =
-        graph()->NewNode(common()->Throw(), initial_element_check_throw,
-                         initial_element_check_fail);
-    NodeProperties::MergeControlToEnd(graph(), common(), throw_node);
-  }
-
   ReplaceWithValue(node, curloop, effect, control);
   return Replace(curloop);
-}  // namespace compiler
+}
 
 Reduction JSCallReducer::ReduceArrayMap(Handle<JSFunction> function,
                                         Node* node) {
@@ -3139,9 +2914,11 @@ Reduction JSCallReducer::ReduceJSCall(Node* node) {
         case Builtins::kArrayFilter:
           return ReduceArrayFilter(function, node);
         case Builtins::kArrayReduce:
-          return ReduceArrayReduce(function, node);
+          return ReduceArrayReduce(function, node,
+                                   ArrayReduceDirection::kArrayReduceLeft);
         case Builtins::kArrayReduceRight:
-          return ReduceArrayReduceRight(function, node);
+          return ReduceArrayReduce(function, node,
+                                   ArrayReduceDirection::kArrayReduceRight);
         case Builtins::kArrayPrototypeFind:
           return ReduceArrayFind(ArrayFindVariant::kFind, function, node);
         case Builtins::kArrayPrototypeFindIndex:

src/compiler/js-call-reducer.h

@@ -52,6 +52,7 @@ class JSCallReducer final : public AdvancedReducer {
   void Finalize() final;
 
  private:
+  enum ArrayReduceDirection { kArrayReduceLeft, kArrayReduceRight };
   Reduction ReduceArrayConstructor(Node* node);
   Reduction ReduceBooleanConstructor(Node* node);
   Reduction ReduceCallApiFunction(Node* node, Handle<JSFunction> function);
@@ -72,8 +73,8 @@ class JSCallReducer final : public AdvancedReducer {
   Reduction ReduceReflectGetPrototypeOf(Node* node);
   Reduction ReduceReflectHas(Node* node);
   Reduction ReduceArrayForEach(Handle<JSFunction> function, Node* node);
-  Reduction ReduceArrayReduce(Handle<JSFunction> function, Node* node);
-  Reduction ReduceArrayReduceRight(Handle<JSFunction> function, Node* node);
+  Reduction ReduceArrayReduce(Handle<JSFunction> function, Node* node,
+                              ArrayReduceDirection direction);
   Reduction ReduceArrayMap(Handle<JSFunction> function, Node* node);
   Reduction ReduceArrayFilter(Handle<JSFunction> function, Node* node);
   enum class ArrayFindVariant : uint8_t { kFind, kFindIndex };

test/mjsunit/array-reduce.js

@@ -641,6 +641,56 @@ assertEquals(undefined, arr.reduceRight(function(val) { return val }));
   assertEquals(total, g());
 })();
 
+(function OptimizedReduceEagerDeoptMiddleOfIterationHoley() {
+  let deopt = false;
+  let array = [, ,11,22,,33,45,56,,6,77,84,93,101,];
+  let f = (a,current) => {
+    print(a);
+    if (current == 6 && deopt) {array[0] = 1.5; }
+    return a + current;
+  };
+  let g = function() {
+    return array.reduce(f);
+  }
+  g(); g();
+  let total = g();
+  %OptimizeFunctionOnNextCall(g);
+  g();
+  deopt = true;
+  g();
+  deopt = false;
+  array = [11,22,33,45,56,6,77,84,93,101];
+  %OptimizeFunctionOnNextCall(g);
+  g();
+  deopt = true;
+  assertEquals(total, g());
+})();
+
+(function OptimizedReduceRightEagerDeoptMiddleOfIterationHoley() {
+  let deopt = false;
+  let array = [, ,11,22,,33,45,56,,6,77,84,93,101,];
+  let f = (a,current) => {
+    print(a);
+    if (current == 6 && deopt) {array[array.length-1] = 1.5; }
+    return a + current;
+  };
+  let g = function() {
+    return array.reduceRight(f);
+  }
+  g(); g();
+  let total = g();
+  %OptimizeFunctionOnNextCall(g);
+  g();
+  deopt = true;
+  g();
+  deopt = false;
+  array = [11,22,33,45,56,6,77,84,93,101];
+  %OptimizeFunctionOnNextCall(g);
+  g();
+  deopt = true;
+  assertEquals(total, g());
+})();
+
 (function ReduceCatch() {
   let f = (a,current) => {
     return a + current;