src/hotspot/share/gc/g1/g1ConcurrentMarkObjArrayProcessor.cpp

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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#include "gc/g1/g1CollectedHeap.inline.hpp"
#include "gc/g1/g1ConcurrentMark.inline.hpp"
#include "gc/g1/g1ConcurrentMarkObjArrayProcessor.inline.hpp"
#include "gc/g1/g1HeapRegion.inline.hpp"
#include "gc/shared/gc_globals.hpp"
#include "memory/memRegion.hpp"
#include "utilities/globalDefinitions.hpp"

void G1CMObjArrayProcessor::push_array_slice(HeapWord* what) {
  _task->push(G1TaskQueueEntry::from_slice(what));
}

size_t G1CMObjArrayProcessor::process_array_slice(objArrayOop obj, HeapWord* start_from, size_t remaining) {
  size_t words_to_scan = MIN2(remaining, (size_t)ObjArrayMarkingStride);

  if (remaining > ObjArrayMarkingStride) {
    push_array_slice(start_from + ObjArrayMarkingStride);
  }

  // Then process current area.
  MemRegion mr(start_from, words_to_scan);
  return _task->scan_objArray(obj, mr);
}

size_t G1CMObjArrayProcessor::process_obj(oop obj) {
  assert(should_be_sliced(obj), "Must be an array object %d and large %zu", obj->is_objArray(), obj->size());

  return process_array_slice(objArrayOop(obj), cast_from_oop<HeapWord*>(obj), objArrayOop(obj)->size());
}

size_t G1CMObjArrayProcessor::process_slice(HeapWord* slice) {

  // Find the start address of the objArrayOop.
  // Shortcut the BOT access if the given address is from a humongous object. The BOT
  // slide is fast enough for "smaller" objects in non-humongous regions, but is slower
  // than directly using heap region table.
  G1CollectedHeap* g1h = G1CollectedHeap::heap();
  G1HeapRegion* r = g1h->heap_region_containing(slice);

  HeapWord* const start_address = r->is_humongous() ?
                                  r->humongous_start_region()->bottom() :
                                  r->block_start(slice);

  assert(cast_to_oop(start_address)->is_objArray(), "Address " PTR_FORMAT " does not refer to an object array ", p2i(start_address));
  assert(start_address < slice,
         "Object start address " PTR_FORMAT " must be smaller than decoded address " PTR_FORMAT,
         p2i(start_address),
         p2i(slice));

  objArrayOop objArray = objArrayOop(cast_to_oop(start_address));

  size_t already_scanned = pointer_delta(slice, start_address);
  size_t remaining = objArray->size() - already_scanned;

  return process_array_slice(objArray, slice, remaining);
}