RFR: 8277180: Intrinsify recursive ObjectMonitor locking for C2 x64 and A64 [v3]

[Erik Österlund]

On Wed, 17 Nov 2021 11:19:09 GMT, Erik Österlund <eosterlund at openjdk.org> wrote:

>> The C2 fast_lock and fast_unlock intrinsics don't support recursive ObjectMonitor locking. Some workloads can significantly benefit from this. Recent ObjectMonitor work has changed heuristics such that ObjectMonitors are deflated less aggressively. Therefore we can expect to see more inflated monitors in workloads where we would usually see more stack locks. That in itself is fine, except that C2 doesn't intrinsify the recursive locking paths for object monitors. Enabling those cases in the C2 code, removes a (~17%) regression we have seen with DaCapo h2 -t 1, and makes a few more benchmarks happy as well.
>
> Erik Österlund has updated the pull request incrementally with one additional commit since the last revision:
> 
>   use increment macro

Any takers for the x86_64 code?

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PR: https://git.openjdk.java.net/jdk/pull/6406