RFR: Make major GC phases exclusive from each other

[Aleksey Shipilev]

On 01/30/2018 11:51 AM, Roman Kennke wrote:
> Full:
> http://cr.openjdk.java.net/~rkennke/exclusive-gc-phases/webrev.01/

Good. I'd still do a few tune-ups:

 *) Keep the asserts in set/unset in ShenandoahSharedBitmap that the incoming value fits into byte.

 *) Arguments should be "mask", not "bit"
  void ShenandoahHeap::set_gc_state_mask_concurrently(uint bit, bool value) {
  void ShenandoahHeap::set_gc_state_mask(uint bit, bool value) {

No need for re-review.

Thanks,
-Aleksey