[turbofan] Introduce a dedicated ConvertTaggedHoleToUndefined operator.

src/heap/heap.cc

 // Copyright 2012 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/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/ast/context-slot-cache.h"
 #include "src/base/bits.h"
@@ skipping 2591 matching lines @@
 void Heap::CreateInitialObjects() {
   HandleScope scope(isolate());
   Factory* factory = isolate()->factory();
 
   // The -0 value must be set before NewNumber works.
   set_minus_zero_value(*factory->NewHeapNumber(-0.0, IMMUTABLE, TENURED));
   DCHECK(std::signbit(minus_zero_value()->Number()) != 0);
 
   set_nan_value(*factory->NewHeapNumber(
       std::numeric_limits<double>::quiet_NaN(), IMMUTABLE, TENURED));
+  set_hole_nan_value(*factory->NewHeapNumber(bit_cast<double>(kHoleNanInt64),
+                                             IMMUTABLE, TENURED));
   set_infinity_value(*factory->NewHeapNumber(V8_INFINITY, IMMUTABLE, TENURED));
   set_minus_infinity_value(
       *factory->NewHeapNumber(-V8_INFINITY, IMMUTABLE, TENURED));
 
   // Allocate initial string table.
   set_string_table(*StringTable::New(isolate(), kInitialStringTableSize));
 
   // Allocate
 
   // Finish initializing oddballs after creating the string table.
   Oddball::Initialize(isolate(), factory->undefined_value(), "undefined",
                       factory->nan_value(), "undefined", Oddball::kUndefined);
 
   // Initialize the null_value.
   Oddball::Initialize(isolate(), factory->null_value(), "null",
                       handle(Smi::FromInt(0), isolate()), "object",
                       Oddball::kNull);
 
   // Initialize the_hole_value.
   Oddball::Initialize(isolate(), factory->the_hole_value(), "hole",
-                      handle(Smi::FromInt(-1), isolate()), "undefined",
+                      factory->hole_nan_value(), "undefined",
                       Oddball::kTheHole);
 
   // Initialize the true_value.
   Oddball::Initialize(isolate(), factory->true_value(), "true",
                       handle(Smi::FromInt(1), isolate()), "boolean",
                       Oddball::kTrue);
 
   // Initialize the false_value.
   Oddball::Initialize(isolate(), factory->false_value(), "false",
                       handle(Smi::FromInt(0), isolate()), "boolean",
@@ skipping 3840 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8