Implement leaf runtime call stub on ARM and corresponding call redirection

runtime/vm/runtime_entry_arm.cc

 // Copyright (c) 2011, 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"
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/runtime_entry.h"
 
 #include "vm/assembler.h"
 #include "vm/simulator.h"
 #include "vm/stub_code.h"
 
 namespace dart {
 
 #define __ assembler->
 
 
 // Generate code to call into the stub which will call the runtime
 // function. Input for the stub is as follows:
 //   SP : points to the arguments and return value array.
 //   R5 : address of the runtime function to call.
 //   R4 : number of arguments to the call.
 void RuntimeEntry::Call(Assembler* assembler) const {
   // 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 = GetEntryPoint();
 #if defined(USING_SIMULATOR)
-  entry = Simulator::RedirectExternalReference(entry, Simulator::kRuntimeCall);
+  // Redirection to leaf runtime calls supports a maximum of 4 arguments passed
+  // in registers.
+  ASSERT(!is_leaf() || (argument_count() <= 4));
+  Simulator::CallKind call_kind =
+      is_leaf() ? Simulator::kLeafRuntimeCall : Simulator::kRuntimeCall;
+  entry = Simulator::RedirectExternalReference(entry, call_kind);
 #endif
   if (is_leaf()) {
     ExternalLabel label(name(), entry);
     __ BranchLink(&label);
   } else {
     __ LoadImmediate(R5, entry);
     __ LoadImmediate(R4, argument_count());
     __ BranchLink(&StubCode::CallToRuntimeLabel());
   }
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM