RFR: LRB backport to 8u

[Aleksey Shipilev]

On 10/23/19 1:16 PM, Roman Kennke wrote:
> Webrev:
> http://cr.openjdk.java.net/~rkennke/lrb-sh8/webrev.00/

The amount of shared changes code gone is impressive.

I think this is ready to go to sh/jdk8 for deeper testing. We still have
aarch64-port/jdk8u-shenandoah as the stable base which we use for releases.

I have retargeted webrev generators to see the difference against jdk8u/jdk8u:
  https://builds.shipilev.net/patch-openjdk-shenandoah-jdk8/
  https://builds.shipilev.net/patch-openjdk-shenandoah-jdk8-only-shared/

...we can check what is going on there after this patchset lands.

Nits:

*) Please try to build without PCH, does it still pass?

*) src/share/vm/c1/c1_LIRGenerator.hpp: I wonder how friending works when Shenandoah is disabled (in
minimal VM build), and ShenandoahBarrierSetC1 is not defined. Actually, I am not sure which #include
gives us, thus my question about PCH.

 155 class LIRGenerator: public InstructionVisitor, public BlockClosure {
 156   friend class ShenandoahBarrierSetC1;

*) src/share/vm/prims/unsafe.cpp: the indenting is a little off:

 314
 315 ensure_satb_referent_alive(p, offset, v);

-- 
Thanks,
-Aleksey