Use CallBootstrapC stub for leaf native calls.

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 716 matching lines @@
   // Push the result place holder initialized to NULL.
   __ PushObject(Object::ZoneHandle(), PP);
   // Pass a pointer to the first argument in RAX.
   if (!function().HasOptionalParameters()) {
     __ leaq(RAX, Address(RBP, (kParamEndSlotFromFp +
                                function().NumParameters()) * kWordSize));
   } else {
     __ leaq(RAX,
             Address(RBP, kFirstLocalSlotFromFp * kWordSize));
   }
+  const intptr_t argc_tag = NativeArguments::ComputeArgcTag(function());
+  const bool is_leaf_call =
+    (argc_tag & NativeArguments::AutoSetupScopeMask()) == 0;
   __ LoadImmediate(
       RBX, Immediate(reinterpret_cast<uword>(native_c_function())), PP);
   __ LoadImmediate(
-      R10, Immediate(NativeArguments::ComputeArgcTag(function())), PP);
-  const ExternalLabel* stub_entry =
-      (is_bootstrap_native()) ? &StubCode::CallBootstrapCFunctionLabel() :
-                                &StubCode::CallNativeCFunctionLabel();
+      R10, Immediate(argc_tag), PP);
+  const ExternalLabel* stub_entry = (is_bootstrap_native() || is_leaf_call) ?
+      &StubCode::CallBootstrapCFunctionLabel() :
+      &StubCode::CallNativeCFunctionLabel();
   compiler->GenerateCall(token_pos(),
                          stub_entry,
                          PcDescriptors::kOther,
                          locs());
   __ popq(result);
 }
 
 
 static bool CanBeImmediateIndex(Value* index, intptr_t cid) {
   if (!index->definition()->IsConstant()) return false;
@@ skipping 5063 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(ArgumentCount());  // Discard arguments.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64