RFR(m): 8221734: Deoptimize with handshakes

[Robbin Ehn]

Hi all, please see this update v4.

I have fixed the simplification Patricio talked about and David's nit.

The interesting part is now the full diff of bias locking cpp file:
http://cr.openjdk.java.net/~rehn/8221734/v4/webrev/src/hotspot/share/runtime/biasedLocking.cpp.sdiff.html
It's very clean.

Full:
http://cr.openjdk.java.net/~rehn/8221734/v4/
Inc:
http://cr.openjdk.java.net/~rehn/8221734/v4/inc/

I have seen no issues in T1-7, KS and other assorted testing.

Thanks, Robbin


On 2019-04-25 14:05, Robbin Ehn wrote:
> Hi all, please review.
> 
> Let's deopt with handshakes.
> Removed VM op Deoptimize, instead we handshake.
> Locks needs to be inflate since we are not in a safepoint.
> 
> Goes on top of:
> https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2019-April/033491.html
> 
> Code:
> http://cr.openjdk.java.net/~rehn/8221734/v1/webrev/index.html
> Issue:
> https://bugs.openjdk.java.net/browse/JDK-8221734
> 
> Passes t1-7 and multiple t1-5 runs.
> 
> A few startup benchmark see a small speedup.
> 
> Thanks, Robbin