Revert of [turbofan] Add support for copy-on-write element stores.

src/compiler/load-elimination.cc

Index: src/compiler/load-elimination.cc
diff --git a/src/compiler/load-elimination.cc b/src/compiler/load-elimination.cc
index 98df1c883b08beb060b311d6006046e568061001..317766d90598577d5891568835e2396632fb1e77 100644
--- a/src/compiler/load-elimination.cc
+++ b/src/compiler/load-elimination.cc
@@ -4,7 +4,6 @@
 
 #include "src/compiler/load-elimination.h"
 
-#include "src/compiler/js-graph.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/simplified-operator.h"
 
@@ -54,8 +53,6 @@
   switch (node->opcode()) {
     case IrOpcode::kCheckMaps:
       return ReduceCheckMaps(node);
-    case IrOpcode::kEnsureWritableFastElements:
-      return ReduceEnsureWritableFastElements(node);
     case IrOpcode::kTransitionElementsKind:
       return ReduceTransitionElementsKind(node);
     case IrOpcode::kLoadField:
@@ -326,29 +323,6 @@
     Node* const map0 = NodeProperties::GetValueInput(node, 1);
     state = state->AddField(object, 0, map0, zone());
   }
-  return UpdateState(node, state);
-}
-
-Reduction LoadElimination::ReduceEnsureWritableFastElements(Node* node) {
-  Node* const object = NodeProperties::GetValueInput(node, 0);
-  Node* const elements = NodeProperties::GetValueInput(node, 1);
-  Node* const effect = NodeProperties::GetEffectInput(node);
-  AbstractState const* state = node_states_.Get(effect);
-  if (state == nullptr) return NoChange();
-  Node* fixed_array_map = jsgraph()->FixedArrayMapConstant();
-  if (Node* const elements_map = state->LookupField(elements, 0)) {
-    // Check if the {elements} already have the fixed array map.
-    if (elements_map == fixed_array_map) {
-      ReplaceWithValue(node, elements, effect);
-      return Replace(elements);
-    }
-  }
-  // We know that the resulting elements have the fixed array map.
-  state = state->AddField(node, 0, fixed_array_map, zone());
-  // Kill the previous elements on {object}.
-  state = state->KillField(object, 2, zone());
-  // Add the new elements on {object}.
-  state = state->AddField(object, 2, node, zone());
   return UpdateState(node, state);
 }
 
@@ -578,19 +552,6 @@
       visited.insert(current);
       if (!current->op()->HasProperty(Operator::kNoWrite)) {
         switch (current->opcode()) {
-          case IrOpcode::kEnsureWritableFastElements: {
-            Node* const object = NodeProperties::GetValueInput(current, 0);
-            Node* const elements = NodeProperties::GetValueInput(current, 1);
-            state = state->KillField(elements, 0, zone());
-            state = state->KillField(object, 2, zone());
-            break;
-          }
-          case IrOpcode::kTransitionElementsKind: {
-            Node* const object = NodeProperties::GetValueInput(current, 0);
-            state = state->KillField(object, 0, zone());
-            state = state->KillField(object, 2, zone());
-            break;
-          }
           case IrOpcode::kStoreField: {
             FieldAccess const& access = FieldAccessOf(current->op());
             Node* const object = NodeProperties::GetValueInput(current, 0);
@@ -605,11 +566,6 @@
             state = state->KillElement(object, index, zone());
             break;
           }
-          case IrOpcode::kStoreBuffer:
-          case IrOpcode::kStoreTypedElement: {
-            // Doesn't affect anything we track with the state currently.
-            break;
-          }
           default:
             return empty_state();
         }