[turbofan] Treat PREMONOMORPHIC like UNINITIALIZED.

src/compiler/js-native-context-specialization.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/js-native-context-specialization.h"
 
 #include "src/accessors.h"
 #include "src/code-factory.h"
 #include "src/compilation-dependencies.h"
 #include "src/compiler/access-builder.h"
@@ skipping 310 matching lines @@
 
 Reduction JSNativeContextSpecialization::ReduceNamedAccessFromNexus(
     Node* node, Node* value, FeedbackNexus const& nexus, Handle<Name> name,
     AccessMode access_mode, LanguageMode language_mode) {
   DCHECK(node->opcode() == IrOpcode::kJSLoadNamed ||
          node->opcode() == IrOpcode::kJSStoreNamed);
   Node* const receiver = NodeProperties::GetValueInput(node, 0);
   Node* const effect = NodeProperties::GetEffectInput(node);
 
   // Check if the {nexus} reports type feedback for the IC.
-  if (nexus.IsUninitialized()) {
+  if (nexus.IsUninitialized() || nexus.IsPremonomorphic()) {
     if ((flags() & kDeoptimizationEnabled) &&
         (flags() & kBailoutOnUninitialized)) {
       return ReduceSoftDeoptimize(
           node,
           DeoptimizeReason::kInsufficientTypeFeedbackForGenericNamedAccess);
     }
     return NoChange();
   }
 
   // Extract receiver maps from the IC using the {nexus}.
@@ skipping 340 matching lines @@
 Reduction JSNativeContextSpecialization::ReduceKeyedAccess(
     Node* node, Node* index, Node* value, KeyedICNexus const& nexus,
     AccessMode access_mode, LanguageMode language_mode,
     KeyedAccessStoreMode store_mode) {
   DCHECK(node->opcode() == IrOpcode::kJSLoadProperty ||
          node->opcode() == IrOpcode::kJSStoreProperty);
   Node* const receiver = NodeProperties::GetValueInput(node, 0);
   Node* const effect = NodeProperties::GetEffectInput(node);
 
   // Check if the {nexus} reports type feedback for the IC.
-  if (nexus.IsUninitialized()) {
+  if (nexus.IsUninitialized() || nexus.IsPremonomorphic()) {
     if ((flags() & kDeoptimizationEnabled) &&
         (flags() & kBailoutOnUninitialized)) {
       return ReduceSoftDeoptimize(
           node,
           DeoptimizeReason::kInsufficientTypeFeedbackForGenericKeyedAccess);
     }
     return NoChange();
   }
 
   // Extract receiver maps from the {nexus}.
@@ skipping 777 matching lines @@
 }
 
 
 SimplifiedOperatorBuilder* JSNativeContextSpecialization::simplified() const {
   return jsgraph()->simplified();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8