Encapsulate megamorphic load/tail-call in hydrogen

src/arm/lithium-arm.cc

Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index 17bfebccd45594072df44c6d298c2a6227147a46..704bb6aa658171f36fc126ff635e755426ede620 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -1099,6 +1099,19 @@ LInstruction* LChunkBuilder::DoCallWithDescriptor(
 }
 
 
+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);
   LOperand* function = UseFixed(instr->function(), r1);