[turbofan][x64] Improve code generation for external reference access.

src/compiler/instruction-selector.cc

Index: src/compiler/instruction-selector.cc
diff --git a/src/compiler/instruction-selector.cc b/src/compiler/instruction-selector.cc
index 89f7de6b8f02c98f6109b84117a2da62b4adcb66..7cb990888b8a08069158c272bbdab9c1879e70ab 100644
--- a/src/compiler/instruction-selector.cc
+++ b/src/compiler/instruction-selector.cc
@@ -23,7 +23,8 @@ InstructionSelector::InstructionSelector(
     InstructionSequence* sequence, Schedule* schedule,
     SourcePositionTable* source_positions, Frame* frame,
     SourcePositionMode source_position_mode, Features features,
-    EnableScheduling enable_scheduling)
+    EnableScheduling enable_scheduling,
+    EnableSerialization enable_serialization)
     : zone_(zone),
       linkage_(linkage),
       sequence_(sequence),
@@ -41,6 +42,7 @@ InstructionSelector::InstructionSelector(
       virtual_register_rename_(zone),
       scheduler_(nullptr),
       enable_scheduling_(enable_scheduling),
+      enable_serialization_(enable_serialization),
       frame_(frame),
       instruction_selection_failed_(false) {
   instructions_.reserve(node_count);
@@ -389,6 +391,12 @@ void InstructionSelector::SetEffectLevel(Node* node, int effect_level) {
   effect_level_[id] = effect_level;
 }
 
+bool InstructionSelector::CanAddressRelativeToRootsRegister() const {
+  return (enable_serialization_ == kDisableSerialization &&
+          (linkage()->GetIncomingDescriptor()->flags() &
+           CallDescriptor::kCanUseRoots));
+}
+
 void InstructionSelector::MarkAsRepresentation(MachineRepresentation rep,
                                                const InstructionOperand& op) {
   UnallocatedOperand unalloc = UnallocatedOperand::cast(op);