Simplify allocation stub for closures.

runtime/vm/stub_code_x64.cc

Index: runtime/vm/stub_code_x64.cc
===================================================================
--- runtime/vm/stub_code_x64.cc	(revision 25558)
+++ runtime/vm/stub_code_x64.cc	(working copy)
@@ -1005,8 +1005,9 @@
   const Immediate& raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   // The generated code is different if the class is parameterized.
-  const bool is_cls_parameterized =
-      cls.type_arguments_field_offset() != Class::kNoTypeArguments;
+  const bool is_cls_parameterized = cls.HasTypeArguments();
+  ASSERT(!cls.HasTypeArguments() ||
+         cls.type_arguments_field_offset() != Class::kNoTypeArguments);
   // kInlineInstanceSize is a constant used as a threshold for determining
   // when the object initialization should be done as a loop or as
   // straight line code.
@@ -1178,8 +1179,7 @@
   const Immediate& raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   ASSERT(func.IsClosureFunction());
-  const bool is_implicit_static_closure =
-      func.IsImplicitStaticClosureFunction();
+  ASSERT(!func.IsImplicitStaticClosureFunction());
   const bool is_implicit_instance_closure =
       func.IsImplicitInstanceClosureFunction();
   const Class& cls = Class::ZoneHandle(func.signature_class());
@@ -1232,14 +1232,7 @@
     __ movq(Address(RAX, Closure::function_offset()), R10);
 
     // Setup the context for this closure.
-    if (is_implicit_static_closure) {
-      ObjectStore* object_store = Isolate::Current()->object_store();
-      ASSERT(object_store != NULL);
-      const Context& empty_context =
-          Context::ZoneHandle(object_store->empty_context());
-      __ LoadObject(R10, empty_context);
-      __ movq(Address(RAX, Closure::context_offset()), R10);
-    } else if (is_implicit_instance_closure) {
+    if (is_implicit_instance_closure) {
       // Initialize the new context capturing the receiver.
 
       const Class& context_class = Class::ZoneHandle(Object::context_class());
@@ -1291,27 +1284,23 @@
   __ EnterStubFrame();
   __ pushq(raw_null);  // Setup space on stack for the return value.
   __ PushObject(func);
-  if (is_implicit_static_closure) {
-    __ CallRuntime(kAllocateImplicitStaticClosureRuntimeEntry);
+  if (is_implicit_instance_closure) {
+    __ pushq(RAX);  // Receiver.
+  }
+  if (has_type_arguments) {
+    __ pushq(RCX);  // Push type arguments of closure to be allocated.
   } else {
-    if (is_implicit_instance_closure) {
-      __ pushq(RAX);  // Receiver.
-    }
-    if (has_type_arguments) {
-      __ pushq(RCX);  // Push type arguments of closure to be allocated.
-    } else {
-      __ pushq(raw_null);  // Push null type arguments.
-    }
-    if (is_implicit_instance_closure) {
-      __ CallRuntime(kAllocateImplicitInstanceClosureRuntimeEntry);
-      __ popq(RAX);  // Pop type arguments.
-      __ popq(RAX);  // Pop receiver.
-    } else {
-      ASSERT(func.IsNonImplicitClosureFunction());
-      __ CallRuntime(kAllocateClosureRuntimeEntry);
-      __ popq(RAX);  // Pop type arguments.
-    }
+    __ pushq(raw_null);  // Push null type arguments.
   }
+  if (is_implicit_instance_closure) {
+    __ CallRuntime(kAllocateImplicitInstanceClosureRuntimeEntry);
+    __ popq(RAX);  // Pop type arguments.
+    __ popq(RAX);  // Pop receiver.
+  } else {
+    ASSERT(func.IsNonImplicitClosureFunction());
+    __ CallRuntime(kAllocateClosureRuntimeEntry);
+    __ popq(RAX);  // Pop type arguments.
+  }
   __ popq(RAX);  // Pop the function object.
   __ popq(RAX);  // Pop the result.
   // RAX: New closure object.