[turbofan] Introduce a dedicated ConvertTaggedHoleToUndefined operator.

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 1140 matching lines @@
       index = effect = graph()->NewNode(simplified()->CheckBounds(), index,
                                         jsgraph()->Constant(Smi::kMaxValue),
                                         effect, control);
     } else {
       // Check that the {index} is in the valid range for the {receiver}.
       index = effect = graph()->NewNode(simplified()->CheckBounds(), index,
                                         length, effect, control);
     }
 
     // Compute the element access.
-    Type* element_type = Type::Any();
+    Type* element_type = Type::NonInternal();
     MachineType element_machine_type = MachineType::AnyTagged();
     if (IsFastDoubleElementsKind(elements_kind)) {
       element_type = Type::Number();
       element_machine_type = MachineType::Float64();
     } else if (IsFastSmiElementsKind(elements_kind)) {
       element_type = type_cache_.kSmi;
     }
     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 (elements_kind == FAST_HOLEY_ELEMENTS ||
           elements_kind == FAST_HOLEY_SMI_ELEMENTS) {
-        element_access.type = Type::Union(
-            element_type,
-            Type::Constant(factory()->the_hole_value(), graph()->zone()),
-            graph()->zone());
+        element_access.type =
+            Type::Union(element_type, Type::Hole(), graph()->zone());
       }
       // 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) {
-        // Perform the hole check on the result.
-        CheckTaggedHoleMode mode = CheckTaggedHoleMode::kNeverReturnHole;
         // Check if we are allowed to turn the hole into undefined.
         if (CanTreatHoleAsUndefined(receiver_maps, native_context)) {
           // Turn the hole into undefined.
-          mode = CheckTaggedHoleMode::kConvertHoleToUndefined;
+          value = graph()->NewNode(simplified()->ConvertTaggedHoleToUndefined(),
+                                   value);
+        } else {
+          // Bailout if we see the hole.
+          value = effect = graph()->NewNode(simplified()->CheckTaggedHole(),
+                                            value, effect, control);
         }
-        value = effect = graph()->NewNode(simplified()->CheckTaggedHole(mode),
-                                          value, effect, control);
       } else if (elements_kind == FAST_HOLEY_DOUBLE_ELEMENTS) {
         // Perform the hole check on the result.
         CheckFloat64HoleMode mode = CheckFloat64HoleMode::kNeverReturnHole;
         // Check if we are allowed to return the hole directly.
         if (CanTreatHoleAsUndefined(receiver_maps, native_context)) {
           // Return the signaling NaN hole directly if all uses are truncating.
           mode = CheckFloat64HoleMode::kAllowReturnHole;
         }
         value = effect = graph()->NewNode(simplified()->CheckFloat64Hole(mode),
                                           value, effect, control);
@@ skipping 273 matching lines @@
 }
 
 
 SimplifiedOperatorBuilder* JSNativeContextSpecialization::simplified() const {
   return jsgraph()->simplified();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8