Initial patch for a64.

src/platform-linux.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 400 matching lines @@
   if (FLAG_break_on_abort) {
     DebugBreak();
   }
   abort();
 }
 
 
 void OS::DebugBreak() {
 // TODO(lrn): Introduce processor define for runtime system (!= V8_ARCH_x,
 //  which is the architecture of generated code).
-#if (defined(__arm__) || defined(__thumb__))
+#if defined(__aarch64__)
+  asm("hlt 0");
+#elif (defined(__arm__) || defined(__thumb__))
   asm("bkpt 0");
 #elif defined(__mips__)
   asm("break");
 #elif defined(__native_client__)
   asm("hlt");
 #else
   asm("int $3");
 #endif
 }
 
@@ skipping 568 matching lines @@
   limit_mutex = CreateMutex();
 }
 
 
 void OS::TearDown() {
   delete limit_mutex;
 }
 
 
 } }  // namespace v8::internal