Adds Runtime call stub and Dart entry stub to ARM64.

runtime/vm/runtime_entry_arm64.cc

 // Copyright (c) 2014, 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_ARM64)
 
 #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, intptr_t argument_count) const {
-  UNIMPLEMENTED();
+  // 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)
+  // Redirection to leaf runtime calls supports a maximum of 4 arguments passed
+  // in registers (maximum 2 double arguments for leaf float runtime calls).

[regis, 2014/04/18 22:15:30]

Di you verify this comment? The ARM64 ABI may be different from the ARM ABI.

[zra, 2014/04/18 23:24:21]

The ABI allows 8 register arguments for both integer and floating point. I've
updated to reflect.

+  ASSERT(argument_count >= 0);
+  ASSERT(!is_leaf() ||
+         (!is_float() && (argument_count <= 4)) ||
+         (argument_count <= 2));
+  Simulator::CallKind call_kind =
+      is_leaf() ? (is_float() ? Simulator::kLeafFloatRuntimeCall
+                              : Simulator::kLeafRuntimeCall)
+                : Simulator::kRuntimeCall;
+  entry =
+      Simulator::RedirectExternalReference(entry, call_kind, argument_count);
+#endif
+  if (is_leaf()) {
+    ASSERT(argument_count == this->argument_count());
+    ExternalLabel label(name(), entry);
+    __ BranchLink(&label, PP);
+  } else {
+    // Argument count is not checked here, but in the runtime entry for a more
+    // informative error message.
+    __ LoadImmediate(R5, entry, PP);
+    __ LoadImmediate(R4, argument_count, PP);
+    __ BranchLink(&StubCode::CallToRuntimeLabel(), PP);
+  }
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64