[turbofan] Properly represent the float64 hole.

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 1944 matching lines @@
       element_machine_type = MachineType::TaggedSigned();
     }
     ElementAccess element_access = {kTaggedBase, FixedArray::kHeaderSize,
                                     element_type, element_machine_type,
                                     kFullWriteBarrier};
 
     // Access the actual element.
     if (access_mode == AccessMode::kLoad) {
       // Compute the real element access type, which includes the hole in case
       // of holey backing stores.
+      if (IsHoleyElementsKind(elements_kind)) {
+        element_access.type =
+            Type::Union(element_type, Type::Hole(), graph()->zone());
+      }
       if (elements_kind == FAST_HOLEY_ELEMENTS ||
           elements_kind == FAST_HOLEY_SMI_ELEMENTS) {
-        element_access.type =
-            Type::Union(element_type, Type::Hole(), graph()->zone());
         element_access.machine_type = MachineType::AnyTagged();
       }
       // Perform the actual backing store access.
       value = effect =
           graph()->NewNode(simplified()->LoadElement(element_access), elements,
                            index, effect, control);
       // Handle loading from holey backing stores correctly, by either mapping
       // the hole to undefined if possible, or deoptimizing otherwise.
       if (elements_kind == FAST_HOLEY_ELEMENTS ||
           elements_kind == FAST_HOLEY_SMI_ELEMENTS) {
@@ skipping 362 matching lines @@
   return jsgraph()->javascript();
 }
 
 SimplifiedOperatorBuilder* JSNativeContextSpecialization::simplified() const {
   return jsgraph()->simplified();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8