review (S) for 6974176: ShouldNotReachHere, instanceKlass.cpp:1426

[Tom Rodriguez]

http://cr.openjdk.java.net/~never/6974176

6974176: ShouldNotReachHere, instanceKlass.cpp:1426
Reviewed-by:

The changes for 6965184 reordered the flush_dependencies and
post_compiled_method_unload which allowed a safepoint to happen in
between.  Zombie nmethods don't have their oops scanned so when
flush_dependencies was run it was reading stale oops.  If the oops
didn't move then it would work as intended but otherwise you might get
various weird failures.  The fix is to restore the original order.  I
also added a No_SafePoint_Verifier and some logic to mark the oops as
potentially stale.  Tested with failing test on SQE machine that
reproduced it reliably, plus nsk suites with -XX:+DeoptimizeALot
-XX:CompileThreshold=100.