A64: Let the MacroAssembler resolve branches to distant targets.

src/a64/assembler-a64-inl.h

 // Copyright 2013 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 475 matching lines @@
     ASSERT(IsRegisterOffset());
     if (extend() == NO_EXTEND) {
       return Operand(regoffset(), shift(), shift_amount());
     } else {
       return Operand(regoffset(), extend(), shift_amount());
     }
   }
 }
 
 
+void Assembler::Unreachable() {
+#ifdef USE_SIMULATOR
+  debug("UNREACHABLE", __LINE__, BREAK);
+#else
+  // Crash by branching to 0. lr now points near the fault.
+  Emit(BLR | Rn(xzr));
+#endif
+}
+
+
 Address Assembler::target_pointer_address_at(Address pc) {
   Instruction* instr = reinterpret_cast<Instruction*>(pc);
   ASSERT(instr->IsLdrLiteralX());
   return reinterpret_cast<Address>(instr->ImmPCOffsetTarget());
 }
 
 
 // Read/Modify the code target address in the branch/call instruction at pc.
 Address Assembler::target_address_at(Address pc) {
   return Memory::Address_at(target_pointer_address_at(pc));
@@ skipping 632 matching lines @@
 
 
 void Assembler::ClearRecordedAstId() {
   recorded_ast_id_ = TypeFeedbackId::None();
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_A64_ASSEMBLER_A64_INL_H_