Missing post-barrier in ReferenceProcessor

The VM has crashed several times in the ReferenceHandler, the symptom is always that we want to enqueue a reference on its ReferenceQueue, but the reference oop is bad (seems to not have been updated).

The bug has happened with Kitchensink and G1, and has been seen on both 32-bit and 64-bit machines in nightly testing.

Example of stack traces:

tack: [0xb55c0000,0xb5611000], sp=0xb560ecac, free space=315k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x9895d5] VMError::report_and_die()+0x185;; VMError::report_and_die()+0x185
V [libjvm.so+0x371568] report_vm_error(char const*, int, char const*, char const*)+0x68;; report_vm_error(char const*, int, char const*, char const*)+0x68
V [libjvm.so+0x3ccc42] frame::retrieve_receiver(RegisterMap*)+0x1f2;; frame::retrieve_receiver(RegisterMap*)+0x1f2
V [libjvm.so+0x887176] SharedRuntime::find_callee_info_helper(JavaThread*, vframeStream&, Bytecodes::Code&, CallInfo&, Thread*)+0x526;; SharedRuntime::find_callee_info_helper(JavaThread*, vframeStream&, Bytecodes::Code&, CallInfo&, Thread*)+0x526
V [libjvm.so+0x88c70e] SharedRuntime::handle_ic_miss_helper(JavaThread*, Thread*)+0x22e;; SharedRuntime::handle_ic_miss_helper(JavaThread*, Thread*)+0x22e
V [libjvm.so+0x88d13f] SharedRuntime::handle_wrong_method_ic_miss(JavaThread*)+0x1cf;; SharedRuntime::handle_wrong_method_ic_miss(JavaThread*)+0x1cf
v ~RuntimeStub::ic_miss_stub
J 1006% C1 java.lang.ref.Reference$ReferenceHandler.run()V (102 bytes) @ 0xf48a120c [0xf48a1000+0x20c]
v ~StubRoutines::call_stub
V [libjvm.so+0x50113d] JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*)+0x17bd;; .L625+0x25c
V [libjvm.so+0x7d2b79] os::os_exception_wrapper(void (*)(JavaValue*, methodHandle*, JavaCallArguments*, Thread*), JavaValue*, methodHandle*, JavaCallArguments*, Thread*)+0x19;; os::os_exception_wrapper(void (*)(JavaValue*, methodHandle*, JavaCallArguments*, Thread*), JavaValue*, methodHandle*, JavaCallArguments*, Thread*)+0x19
V [libjvm.so+0x503690] JavaCalls::call_virtual(JavaValue*, KlassHandle, Symbol*, Symbol*, JavaCallArguments*, Thread*)+0x650;; JavaCalls::call_virtual(JavaValue*, KlassHandle, Symbol*, Symbol*, JavaCallArguments*, Thread*)+0x650
V [libjvm.so+0x504075] JavaCalls::call_virtual(JavaValue*, Handle, KlassHandle, Symbol*, Symbol*, Thread*)+0x95;; JavaCalls::call_virtual(JavaValue*, Handle, KlassHandle, Symbol*, Symbol*, Thread*)+0x95
V [libjvm.so+0x5de3b1] thread_entry(JavaThread*, Thread*)+0xc1;; thread_entry(JavaThread*, Thread*)+0xc1
V [libjvm.so+0x92d0e4] JavaThread::thread_main_inner()+0x234;; JavaThread::thread_main_inner()+0x234
V [libjvm.so+0x92d484] JavaThread::run()+0x2e4;; JavaThread::run()+0x2e4
V [libjvm.so+0x7db819] java_start(Thread*)+0x119;; java_start(Thread*)+0x119
C [libpthread.so.0+0x6a49] abort@@GLIBC_2.0+0x6a49

0 0xf77f9430 in __kernel_vsyscall ()
#1 0x4a71db01 in raise () from sysroot/lib/libc.so.6
#2 0x4a71f3da in abort () from sysroot/lib/libc.so.6
#3 0xf6f9e104 in os::abort(bool) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#4 0xf714ec51 in VMError::report_and_die() ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#5 0xf714f22e in crash_handler(int, siginfo*, void*) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#6 <signal handler called>
#7 0xf6f910cb in os::is_first_C_frame(frame*) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#8 0xf714cfb7 in VMError::report(outputStream*) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#9 0xf714e5d5 in VMError::report_and_die() ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#10 0xf6fa8ff9 in JVM_handle_linux_signal ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#11 0xf6f9a1ef in signalHandler(int, siginfo*, void*) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#12 <signal handler called>
#13 J 505 C1 java.lang.ref.ReferenceQueue.enqueue(Ljava/lang/ref/Reference;)Z (119 bytes) @ 0xf7a3b1c7 [0xf7a3b1c0+0x7]
#14 0xf6cc613d in JavaCalls::call_helper(JavaValue*, methodHandle*, JavaCallArguments*, Thread*) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#15 0xf6f97b79 in os::os_exception_wrapper(void (*)(JavaValue*, methodHandle*, JavaCallArguments*, Thread*), JavaValue*, methodHandle*, JavaCallArguments*, Thread*) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#16 0xf6cc8690 in JavaCalls::call_virtual(JavaValue*, KlassHandle, Symbol*, Symbol*, JavaCallArguments*, Thread*) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#17 0xf6cc9075 in JavaCalls::call_virtual(JavaValue*, Handle, KlassHandle, Symbol*, Symbol*, Thread*) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#18 0xf6da33b1 in thread_entry(JavaThread*, Thread*) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#19 0xf70f20e4 in JavaThread::thread_main_inner() ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#20 0xf70f2484 in JavaThread::run() ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#21 0xf6fa0819 in java_start(Thread*) ()
   from sysroot/scratch/local/aurora/sandbox/sca/vmsqe/jdk/nightly/fastdebug/gc_baseline/linux-i586/jre/lib/i386/client/libjvm.so
#22 0x4a8c0a49 in start_thread () from sysroot/lib/libpthread.so.0
#23 0x4a7d1e1e in clone () from sysroot/lib/libc.so.6