RFR: JDK-8277056: Combining several C2 Print* flags asserts in xmlStream::pop_tag

[Xin Liu]

On Wed, 20 Apr 2022 06:01:03 GMT, Tobias Hartmann <thartmann at openjdk.org> wrote:

> `process_if_requested_with_exit_check`

I think this is exactly what happened in the problem described in the first place. 
... -> SafepointMechanism::process_if_requested_with_exit_check -> SafepointSynchronize::block ->   ttyLocker::break_tty_lock_for_safepoint

ttylocker may quietly get released inside of ciMetadata::print_metadata. it's not thread-safe until you regain ttylock.

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PR: https://git.openjdk.java.net/jdk/pull/8203