RFR (S/M): 8184348: Merge G1ConcurrentMark::par_mark() and G1ConcurrentMark::grayRoot()

[Aleksey Shipilev]

On 07/14/2017 01:19 PM, Thomas Schatzl wrote:
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8184348/webrev/

*) I'd probably split the assert with newlines. Makes webrevs tidier!

*) This is not needed, because par_mark already has the optimistic check, down
below in Bitmap::par_set_bit?

  54   // Dirty read to avoid CAS.
  55   if (_nextMarkBitMap->is_marked(obj_addr)) {
  56     return false;
  57   }

*) So, mark_reference_grey used to be called from G1CMSATBBufferClosure on
objects below TAMS, but now it would get called on objects past TAMS too?
Doesn't G1 verify there are no bits set in bitmap past TAMS
(G1HeapVerifier::verify_no_bits_over_tams)?

Thanks,
-Aleksey

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