Encapsulate megamorphic load/tail-call in hydrogen

src/arm64/lithium-arm64.cc

Index: src/arm64/lithium-arm64.cc
diff --git a/src/arm64/lithium-arm64.cc b/src/arm64/lithium-arm64.cc
index 739f43ad1ff55aa95f145d2ddc7ab33f86bc7345..0975587fe643c135ffdae36d95f50242a3a83d02 100644
--- a/src/arm64/lithium-arm64.cc
+++ b/src/arm64/lithium-arm64.cc
@@ -1562,6 +1562,19 @@ LInstruction* LChunkBuilder::DoInstanceOfKnownGlobal(
 }
 
 
+LInstruction* LChunkBuilder::DoTailCallThroughMegamorphicCache(
+    HTailCallThroughMegamorphicCache* instr) {
+  LOperand* context = UseFixed(instr->context(), cp);
+  LOperand* receiver_register =
+      UseFixed(instr->receiver(), LoadDescriptor::ReceiverRegister());
+  LOperand* name_register =
+      UseFixed(instr->name(), LoadDescriptor::NameRegister());
+  // Not marked as call. It can't deoptimize, and it never returns.
+  return new (zone()) LTailCallThroughMegamorphicCache(
+      context, receiver_register, name_register);
+}
+
+
 LInstruction* LChunkBuilder::DoInvokeFunction(HInvokeFunction* instr) {
   LOperand* context = UseFixed(instr->context(), cp);
   // The function is required (by MacroAssembler::InvokeFunction) to be in x1.