[aarch64-port-dev ] JTREG hotspot issues

[Andy Johnson]

The JTREG regression tests in hotspot/test are finding the following
errors, all a result of finding Unimplemented stubs:

runtime/6294277/SourceDebugExtension.java
#  Internal Error
(~/openjdk-8/jdk8/hotspot/src/cpu/aarch64/vm/interp_masm_aarch64.cpp:54),
pid=2981, tid=547984654864
#  Error: Unimplemented()
void InterpreterMacroAssembler::check_and_handle_popframe(Register
java_thread) {
  if (JvmtiExport::can_pop_frame()) {
    Unimplemented();
  }
}

gc/8000311/Test8000311.java
gc/TestG1ZeroPGCTJcmdThreadPrint
gc/7168848/HumongousAlloc
#  Internal Error
(~/openjdk-8/jdk8/hotspot/src/cpu/aarch64/vm/macroAssembler_aarch64.cpp:2254),
pid=1341, tid=548143497744
#  Error: Unimplemented()
void MacroAssembler::g1_write_barrier_pre(Register obj,
                                          Register pre_val,
                                          Register thread,
                                          Register tmp,
                                          bool tosca_live,
                                          bool expand_call) {
Unimplemented(); }

Is there any plan to implement these features?  There may be periodic
failures in the G1 garbage collector if the latter is not implemented,
unless there is a way to bypass this call, other than specifying an
alternate garbage collector.