[turbofan][x64] Use the root register for comparisons with certain roots.

src/compiler/instruction-selector.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/instruction-selector.h"
 
 #include <limits>
 
 #include "src/base/adapters.h"
 #include "src/compiler/instruction-selector-impl.h"
@@ skipping 374 matching lines @@
 }
 
 void InstructionSelector::SetEffectLevel(Node* node, int effect_level) {
   DCHECK_NOT_NULL(node);
   size_t const id = node->id();
   DCHECK_LT(id, effect_level_.size());
   effect_level_[id] = effect_level;
 }
 
 bool InstructionSelector::CanAddressRelativeToRootsRegister() const {
-  return (enable_serialization_ == kDisableSerialization &&
-          (linkage()->GetIncomingDescriptor()->flags() &
-           CallDescriptor::kCanUseRoots));
+  return enable_serialization_ == kDisableSerialization &&
+         CanUseRootsRegister();
+}
+
+bool InstructionSelector::CanUseRootsRegister() const {
+  return linkage()->GetIncomingDescriptor()->flags() &
+         CallDescriptor::kCanUseRoots;
 }
 
 void InstructionSelector::MarkAsRepresentation(MachineRepresentation rep,
                                                const InstructionOperand& op) {
   UnallocatedOperand unalloc = UnallocatedOperand::cast(op);
   sequence()->MarkAsRepresentation(rep, unalloc.virtual_register());
 }
 
 
 void InstructionSelector::MarkAsRepresentation(MachineRepresentation rep,
@@ skipping 1713 matching lines @@
   return new (instruction_zone()) FrameStateDescriptor(
       instruction_zone(), state_info.type(), state_info.bailout_id(),
       state_info.state_combine(), parameters, locals, stack,
       state_info.shared_info(), outer_state);
 }
 
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8