RFR: 8254264: Remove redundant cross_modify_fence()

[Patricio Chilano Mateo]

On Mon, 19 Oct 2020 22:04:46 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> Hi all,
>> 
>> Please review the following patch that removes some uneeded uses of cross_modify_fence() in common code, in particular
>> from ~ThreadBlockInVM(), ~ThreadBlockInVMWithDeadlockCheck() and java_suspend_self_with_safepoint_check(). These fences
>> were added before each JavaThread had to disarm itself (8230594). After a safepoint/handshake each JavaThread will
>> always call SafepointMechanism::process_if_requested_slow() when transitioning out of the safe state and will execute a
>> cross_modify_fence(). Tested with mach5 tiers1-7.  Thanks, Patricio
>
> Thumbs up! Had to read through the comments a couple of
> times along with the code before I convinced myself all was
> okay. Thanks for testing Mach5 Tier[1-7].

> Heads-up: The build and test tasks appear to be unhappy.

Yes, commit v1 was done after 8173585 was pushed but before the issues introduced by it were fixed. I can merge with
master to make it happy.  : )

> Thumbs up! Had to read through the comments a couple of
> times along with the code before I convinced myself all was
> okay. Thanks for testing Mach5 Tier[1-7].

Thanks Dan!

-------------

PR: https://git.openjdk.java.net/jdk/pull/655