The usages of counter_fpu_stack were removed with JDK-8351156 when the FPU stack support was removed. But the definition in the Counter enum was missed to clean up. When now printing the countesr with -XX:+CountLinearScan -XX:+CITime, we reach a ShouldNotReach in LinearScanStatistic::counter_name() for Counter::counter_fpu_stack because there is no longer an entry there.

To reproduce:

$ java -XX:+CountLinearScan -XX:+CITime --version

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/opt/mach5/mesos/work_dir/slaves/da1065b5-7b94-4f0d-85e9-a3a252b9a32e-S34988/frameworks/1735e8a2-a1db-478c-8104-60c8b0af87dd-0196/executors/f3243ba7-b34c-4eb2-9276-e1867faa18c0/runs/041c28e0-2159-4d53-90b3-ac7f539a1569/workspace/open/src/hotspot/share/c1/c1_LinearScan.cpp:6466), pid=159934, tid=159935
# Error: ShouldNotReachHere()
...........
Stack: [0x00007fbac9f00000,0x00007fbaca000000], sp=0x00007fbac9ffe820, free space=1018k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x940e92] LinearScanStatistic::counter_name(int)+0x2d2 (c1_LinearScan.cpp:6466)
V [libjvm.so+0x941381] LinearScanStatistic::print(char const*)+0x111 (c1_LinearScan.cpp:6506)
V [libjvm.so+0x941427] LinearScan::print_statistics()+0x17 (c1_LinearScan.cpp:3085)
V [libjvm.so+0xbbf2a2] CompileBroker::print_times(bool, bool)+0x3b2 (compileBroker.cpp:2762)
V [libjvm.so+0x10e591f] print_statistics()+0x111f (java.cpp:251)
V [libjvm.so+0x10e6b7a] before_exit(JavaThread*, bool)+0x52a (java.cpp:517)
V [libjvm.so+0x1bd70c7] Threads::destroy_vm()+0x1d7 (threads.cpp:995)
V [libjvm.so+0x124448c] jni_DestroyJavaVM+0xac (jni.cpp:3773)
C [libjli.so+0x41de] JavaMain+0x3ee (java.c:668)
C [libjli.so+0x8099] ThreadJavaMain+0x9 (java_md.c:646)