Fatal error when running with +UseZGC

[Mohammad Dashti]

When running with a release/fastdebug/slowdebug build, I get a fatal error
only with ZGC. I get this error when running on an AMD machine, I tried the
same build on an Intel box and it runs without problems. Here are the
relevant details (I simply run "java -XX:+UseZGC -version"):

Host: A10-9600P, AMD A10-9600P RADEON R5, 10 COMPUTE CORES 4C+6G, 4 cores,
11G, Ubuntu 16.04.3 LTS

# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (zgc/src/hotspot/share/opto/machnode.cpp:580), pid=25940,
tid=25952
#  assert((uint)_ideal_reg < (uint)_last_machine_leaf &&
Type::mreg2type[_ideal_reg]) failed: in bounds

And here's the call stack:

Current thread (0x00007f23401967c0):  JavaThread "C2 CompilerThread0"
daemon [_thread_in_native, id=25952,
stack(0x00007f2322d33000,0x00007f2322e34000)]


Current CompileTask:
C2:    280   27       4       java.lang.String::charAt (25 bytes)
0x00007f2323604738 - 0x00007f2323604751

Stack: [0x00007f2322d33000,0x00007f2322e34000],  sp=0x00007f2322e2eac0,
free space=1006k
Native frames: (J=compiled Java code, A=aot compiled Java code,
j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0x15968ae]  VMError::report_and_die(int, char const*, char
const*, __va_list_tag*, Thread*, unsigned char*, void*, void*, char const*,
int, unsigned long)+0x4ce
V  [libjvm.so+0x159741f]  VMError::report_and_die(Thread*, char const*,
int, char const*, char const*, __va_list_tag*)+0x2f
V  [libjvm.so+0xaa53e2]  report_vm_error(char const*, int, char const*,
char const*, ...)+0x112
V  [libjvm.so+0x107b00a]  MachProjNode::bottom_type() const+0x12a
V  [libjvm.so+0x89c872]  PhaseChaitin::gather_lrg_masks(bool)+0x192
V  [libjvm.so+0xce2c2b]  PhaseCFG::global_code_motion()+0x11eb
V  [libjvm.so+0xce2ee1]  PhaseCFG::do_global_code_motion()+0x51
V  [libjvm.so+0xa0177a]  Compile::Code_Gen()+0x2ca
V  [libjvm.so+0xa0fbb0]  Compile::Compile(ciEnv*, C2Compiler*, ciMethod*,
int, bool, bool, bool, DirectiveSet*)+0x1450
V  [libjvm.so+0x854e4b]  C2Compiler::compile_method(ciEnv*, ciMethod*, int,
DirectiveSet*)+0x2db
V  [libjvm.so+0xa1bf36]
CompileBroker::invoke_compiler_on_method(CompileTask*)+0x7d6
V  [libjvm.so+0xa1db98]  CompileBroker::compiler_thread_loop()+0x408
V  [libjvm.so+0x14f6825]  JavaThread::thread_main_inner()+0x1e5
V  [libjvm.so+0x14f6ab8]  JavaThread::run()+0x208
V  [libjvm.so+0x1261102]  thread_native_entry(Thread*)+0x112

I believe this issue is similar to a previous message:
http://mail.openjdk.java.net/pipermail/zgc-dev/2018-March/000169.html

Thanks,
Mohammad