In GrowMode, force the value to the right representation to avoid deopts between storing the length…

src/hydrogen.cc

 // Copyright 2013 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/hydrogen.h"
 
 #include <algorithm>
 
 #include "src/v8.h"
 
@@ skipping 2461 matching lines @@
   // In case val is stored into a fast smi array, assure that the value is a smi
   // before manipulating the backing store. Otherwise the actual store may
   // deopt, leaving the backing store in an invalid state.
   if (access_type == STORE && IsFastSmiElementsKind(elements_kind) &&
       !val->type().IsSmi()) {
     val = AddUncasted<HForceRepresentation>(val, Representation::Smi());
   }
 
   if (IsGrowStoreMode(store_mode)) {
     NoObservableSideEffectsScope no_effects(this);
+    Representation representation = HStoreKeyed::RequiredValueRepresentation(
+        elements_kind, STORE_TO_INITIALIZED_ENTRY);
+    val = AddUncasted<HForceRepresentation>(val, representation);
     elements = BuildCheckForCapacityGrow(checked_object, elements,
                                          elements_kind, length, key,
                                          is_js_array, access_type);
     checked_key = key;
   } else {
     checked_key = Add<HBoundsCheck>(key, length);
 
     if (access_type == STORE && (fast_elements || fast_smi_only_elements)) {
       if (store_mode == STORE_NO_TRANSITION_HANDLE_COW) {
         NoObservableSideEffectsScope no_effects(this);
@@ skipping 176 matching lines @@
     ElementsKind elements_kind,
     PropertyAccessType access_type,
     LoadKeyedHoleMode load_mode) {
   if (access_type == STORE) {
     ASSERT(val != NULL);
     if (elements_kind == EXTERNAL_UINT8_CLAMPED_ELEMENTS ||
         elements_kind == UINT8_CLAMPED_ELEMENTS) {
       val = Add<HClampToUint8>(val);
     }
     return Add<HStoreKeyed>(elements, checked_key, val, elements_kind,
-                            elements_kind == FAST_SMI_ELEMENTS
-                              ? STORE_TO_INITIALIZED_ENTRY
-                              : INITIALIZING_STORE);
+                            STORE_TO_INITIALIZED_ENTRY);
   }
 
   ASSERT(access_type == LOAD);
   ASSERT(val == NULL);
   HLoadKeyed* load = Add<HLoadKeyed>(
       elements, checked_key, dependency, elements_kind, load_mode);
   if (FLAG_opt_safe_uint32_operations &&
       (elements_kind == EXTERNAL_UINT32_ELEMENTS ||
        elements_kind == UINT32_ELEMENTS)) {
     graph()->RecordUint32Instruction(load);
@@ skipping 9783 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal