src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

rev 7471 : 8060025: Object copy time regressions after JDK-8031323 and JDK-8057536
Summary: Evaluate and improve object copy time by micro-optimizations and splitting out slow and fast paths aggressively.
Reviewed-by:
Contributed-by: Tony Printezis <tprintezis@twitter.com>, Thomas Schatzl <thomas.schatzl@oracle.com>
rev 7472 : [mq]: 8060025-mikael-review1

*** 2761,2771 ****
    case VerifyOption_G1UseMarkWord:
      return false;
    default:
      ShouldNotReachHere();
    }
!   return false; // keep some compilers happy
  }
  
  HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
    switch (vo) {
    case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
--- 2761,2771 ----
    case VerifyOption_G1UseMarkWord:
      return false;
    default:
      ShouldNotReachHere();
    }
!   return false; // Keep some compilers happy
  }
  
  HeapWord* G1CollectedHeap::top_at_mark_start(HeapRegion* hr, VerifyOption vo) {
    switch (vo) {
    case VerifyOption_G1UsePrevMarking: return hr->prev_top_at_mark_start();
*** 5767,5779 ****
        _ct_bs->clear(MemRegion(r->bottom(), r->end()));
      }
    }
  };
  
! #ifdef PRODUCT
! bool G1CollectedHeap::check_cset_fast_test() { return true; }
! #else
  class G1VerifyCardTableCleanup: public HeapRegionClosure {
    G1CollectedHeap* _g1h;
    G1SATBCardTableModRefBS* _ct_bs;
  public:
    G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)
--- 5767,5777 ----
        _ct_bs->clear(MemRegion(r->bottom(), r->end()));
      }
    }
  };
  
! #ifndef PRODUCT
  class G1VerifyCardTableCleanup: public HeapRegionClosure {
    G1CollectedHeap* _g1h;
    G1SATBCardTableModRefBS* _ct_bs;
  public:
    G1VerifyCardTableCleanup(G1CollectedHeap* g1h, G1SATBCardTableModRefBS* ct_bs)