[turbofan] Introduce a dedicated ConvertTaggedHoleToUndefined operator.

src/compiler/typer.cc

 // Copyright 2014 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/typer.h"
 
 #include <iomanip>
 
 #include "src/base/flags.h"
 #include "src/bootstrapper.h"
@@ skipping 1216 matching lines @@
   UNREACHABLE();
   return nullptr;
 }
 
 
 Type* Typer::Visitor::WrapContextTypeForInput(Node* node) {
   Type* outer = TypeOrNone(NodeProperties::GetContextInput(node));
   if (outer->Is(Type::None())) {
     return Type::None();
   } else {
-    DCHECK(outer->Maybe(Type::Internal()));
+    DCHECK(outer->Maybe(Type::OtherInternal()));
     return Type::Context(outer, zone());
   }
 }
 
 
 Type* Typer::Visitor::TypeJSCreateFunctionContext(Node* node) {
   return WrapContextTypeForInput(node);
 }
 
 
@@ skipping 328 matching lines @@
   Type* arg = Operand(node, 0);
   return Type::Intersect(arg, typer_->cache_.kSmi, zone());
 }
 
 Type* Typer::Visitor::TypeCheckFloat64Hole(Node* node) {
   Type* type = Operand(node, 0);
   return type;
 }
 
 Type* Typer::Visitor::TypeCheckTaggedHole(Node* node) {
-  CheckTaggedHoleMode mode = CheckTaggedHoleModeOf(node->op());
   Type* type = Operand(node, 0);
   type = Type::Intersect(type, Type::NonInternal(), zone());
-  switch (mode) {
-    case CheckTaggedHoleMode::kConvertHoleToUndefined: {
-      // The hole is turned into undefined.
-      type = Type::Union(type, Type::Undefined(), zone());
-      break;
-    }
-    case CheckTaggedHoleMode::kNeverReturnHole: {
-      // We deoptimize in case of the hole.
-      break;
-    }
+  return type;
+}
+
+Type* Typer::Visitor::TypeConvertTaggedHoleToUndefined(Node* node) {
+  Type* type = Operand(node, 0);
+  if (type->Maybe(Type::Hole())) {
+    // Turn "the hole" into undefined.
+    type = Type::Intersect(type, Type::NonInternal(), zone());
+    type = Type::Union(type, Type::Undefined(), zone());
   }
   return type;
 }
 
 Type* Typer::Visitor::TypeAllocate(Node* node) { return Type::TaggedPointer(); }
 
 Type* Typer::Visitor::TypeLoadField(Node* node) {
   return FieldAccessOf(node->op()).type;
 }
 
@@ skipping 721 matching lines @@
   }
   if (Type::IsInteger(*value)) {
     return Type::Range(value->Number(), value->Number(), zone());
   }
   return Type::Constant(value, zone());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8