Use CallBootstrapC stub for leaf native calls.

runtime/vm/intermediate_language_arm.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_ARM.
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/cpu.h"
@@ skipping 906 matching lines @@
   if (!function().HasOptionalParameters()) {
     __ AddImmediate(R2, FP, (kParamEndSlotFromFp +
                              function().NumParameters()) * kWordSize);
   } else {
     __ AddImmediate(R2, FP, kFirstLocalSlotFromFp * kWordSize);
   }
   // Compute the effective address. When running under the simulator,
   // this is a redirection address that forces the simulator to call
   // into the runtime system.
   uword entry = reinterpret_cast<uword>(native_c_function());
+  const intptr_t argc_tag = NativeArguments::ComputeArgcTag(function());
+  const bool is_leaf_call =
+    (argc_tag & NativeArguments::AutoSetupScopeMask()) == 0;
   const ExternalLabel* stub_entry;
-  if (is_bootstrap_native()) {
+  if (is_bootstrap_native() || is_leaf_call) {
     stub_entry = &StubCode::CallBootstrapCFunctionLabel();
 #if defined(USING_SIMULATOR)
     entry = Simulator::RedirectExternalReference(
         entry, Simulator::kBootstrapNativeCall, function().NumParameters());
 #endif
   } else {
     // In the case of non bootstrap native methods the CallNativeCFunction
     // stub generates the redirection address when running under the simulator
     // and hence we do not change 'entry' here.
     stub_entry = &StubCode::CallNativeCFunctionLabel();
 #if defined(USING_SIMULATOR)
     if (!function().IsNativeAutoSetupScope()) {
       entry = Simulator::RedirectExternalReference(
           entry, Simulator::kBootstrapNativeCall, function().NumParameters());
     }
 #endif
   }
   __ LoadImmediate(R5, entry);
-  __ LoadImmediate(R1, NativeArguments::ComputeArgcTag(function()));
+  __ LoadImmediate(R1, argc_tag);
   compiler->GenerateCall(token_pos(),
                          stub_entry,
                          PcDescriptors::kOther,
                          locs());
   __ Pop(result);
 }
 
 
 LocationSummary* StringFromCharCodeInstr::MakeLocationSummary(Isolate* isolate,
                                                               bool opt) const {
@@ skipping 5389 matching lines @@
   compiler->GenerateCall(token_pos(),
                          &label,
                          PcDescriptors::kOther,
                          locs());
   __ Drop(ArgumentCount());  // Discard arguments.
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM