Heads-up: CTW failure with LRB

[Aleksey Shipilev]

Seems like reproduce more or less reliably:

$ CONF=linux-x86_64-server-fastdebug make run-test TEST=applications/ctw/modules/java_base_2.java
TEST_VM_OPTS="-XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC -XX:+UnlockDiagnosticVMOptions
-XX:+ShenandoahVerifyOptoBarriers"

java.lang.AssertionError: There were 1 errors:[{modules_java_base_3117: failed during compilation of
class #4583 : sun/nio/cs/ISO_8859_15}]

Look around for hs_err, it would mention:

#  Internal Error
(/home/shade/trunks/shenandoah-jdk/src/hotspot/share/gc/shenandoah/c2/shenandoahSupport.cpp:3251),
pid=26762, tid=7608
#  Error: ShouldNotReachHere()

Current CompileTask:
C2: 258504 49993   !b  4       sun.nio.cs.ISO_8859_1$Encoder::encodeArrayLoop (369 bytes)

Stack: [0x00007f5fdc76a000,0x00007f5fdc86b000],  sp=0x00007f5fdc864480,  free space=1001k
Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native
code)
V  [libjvm.so+0x15e49cb]  ShenandoahLoadReferenceBarrierNode::get_barrier_strength()+0x67b
V  [libjvm.so+0x15e51b3]  ShenandoahBarrierC2Support::pin_and_expand(PhaseIdealLoop*)+0x213
V  [libjvm.so+0x1547f47]  ShenandoahBarrierSetC2::optimize_loops(PhaseIdealLoop*, LoopOptsMode,
VectorSet&, Node_Stack&, Node_List&) const+0xc7
V  [libjvm.so+0x1159882]  PhaseIdealLoop::build_and_optimize(LoopOptsMode)+0xc02
V  [libjvm.so+0x15daf23]  ShenandoahBarrierC2Support::expand(Compile*, PhaseIterGVN&)+0x2b3
V  [libjvm.so+0x1547e0f]  ShenandoahBarrierSetC2::expand_barriers(Compile*, PhaseIterGVN&) const+0xf
V  [libjvm.so+0x9891bd]  Compile::Optimize()+0xced
V  [libjvm.so+0x98a360]  Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool, bool,
DirectiveSet*)+0xe90
V  [libjvm.so+0x7c04ad]  C2Compiler::compile_method(ciEnv*, ciMethod*, int, DirectiveSet*)+0x10d
V  [libjvm.so+0x9968d5]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x3f5
V  [libjvm.so+0x9979f8]  CompileBroker::compiler_thread_loop()+0x498
V  [libjvm.so+0x17646da]  JavaThread::thread_main_inner()+0x26a
V  [libjvm.so+0x176c3ee]  JavaThread::run()+0x1ae

-Aleksey