Implement native call stub on ARM and native call redirection in ARM simulator.

runtime/vm/os_macos.cc

Index: runtime/vm/os_macos.cc
===================================================================
--- runtime/vm/os_macos.cc	(revision 19653)
+++ runtime/vm/os_macos.cc	(working copy)
@@ -7,6 +7,7 @@
 
 #include "vm/os.h"
 
+#include <dlfcn.h>  // NOLINT
 #include <errno.h>  // NOLINT
 #include <limits.h>  // NOLINT
 #include <mach/mach.h>  // NOLINT
@@ -190,6 +191,18 @@
 }
 
 
+const char* OS::ReverseLookupSymbol(uword address) {
+  // TODO(regis): This does not work for symbols of the main program.
+  // Passing -export-dynamic to the linker does not help.
+  Dl_info info;
+  if (dladdr(reinterpret_cast<void*>(address), &info)) {
+    return info.dli_sname;
+  } else {
+    return NULL;
+  }
+}
+
+
 void OS::PrintErr(const char* format, ...) {
   va_list args;
   va_start(args, format);