Create and cache method extraction stub in the ICData.

runtime/vm/stub_code_x64.cc

Index: runtime/vm/stub_code_x64.cc
diff --git a/runtime/vm/stub_code_x64.cc b/runtime/vm/stub_code_x64.cc
index 823558f8acac4e92c81702e4e51c502ebc934eca..265e545bd67e37c1dbb7cd884b9408e6f7516126 100644
--- a/runtime/vm/stub_code_x64.cc
+++ b/runtime/vm/stub_code_x64.cc
@@ -990,6 +990,38 @@ void StubCode::GenerateUpdateStoreBufferStub(Assembler* assembler) {
 }
 
 
+void StubCode::GenerateMethodExtractor(Assembler* assembler,
+                                       const Function& closure_function) {
+  const Immediate raw_null =
+      Immediate(reinterpret_cast<intptr_t>(Object::null()));
+
+  AssemblerMacros::EnterStubFrame(assembler);
+  __ movq(RAX, Address(RBP, 2 * kWordSize));
+  __ pushq(RAX);  // Push receiver.
+
+  __ LoadClass(R10, RAX);
+  // Compute instance type arguments into R13.
+  Label has_no_type_arguments;
+  __ movq(R13, raw_null);
+  __ movq(RDI, FieldAddress(R10,
+      Class::type_arguments_field_offset_in_words_offset()));
+  __ cmpq(RDI, Immediate(Class::kNoTypeArguments));
+  __ j(EQUAL, &has_no_type_arguments, Assembler::kNearJump);
+  __ movq(R13, FieldAddress(RAX, RDI, TIMES_8, 0));
+  __ Bind(&has_no_type_arguments);
+  __ pushq(R13);  // Push type arguments.
+
+  const Code& stub = Code::Handle(
+      GetAllocationStubForClosure(
+          Function::ZoneHandle(closure_function.raw())));
+  const ExternalLabel label(closure_function.ToCString(), stub.EntryPoint());
+  __ call(&label);
+  __ Drop(2);  // Drop receiver and type arguments.
+  __ LeaveFrame();
+  __ ret();
+}
+
+
 // Called for inline allocation of objects.
 // Input parameters:
 //   RSP + 16 : type arguments object (only if class is parameterized).