src/share/vm/gc/g1/heapRegion.cpp

rev 13047 : imported patch 8071280-specialize-heapregion-oops-on-card-seq-iterate

*** 347,462 ****
           "marked: " SIZE_FORMAT " used: " SIZE_FORMAT, marked_bytes, used());
    _prev_top_at_mark_start = top();
    _prev_marked_bytes = marked_bytes;
  }
  
- // Humongous objects are allocated directly in the old-gen.  Need
- // special handling for concurrent processing encountering an
- // in-progress allocation.
- static bool do_oops_on_card_in_humongous(MemRegion mr,
-                                          G1UpdateRSOrPushRefOopClosure* cl,
-                                          HeapRegion* hr,
-                                          G1CollectedHeap* g1h) {
-   assert(hr->is_humongous(), "precondition");
-   HeapRegion* sr = hr->humongous_start_region();
-   oop obj = oop(sr->bottom());
- 
-   // If concurrent and klass_or_null is NULL, then space has been
-   // allocated but the object has not yet been published by setting
-   // the klass.  That can only happen if the card is stale.  However,
-   // we've already set the card clean, so we must return failure,
-   // since the allocating thread could have performed a write to the
-   // card that might be missed otherwise.
-   if (!g1h->is_gc_active() && (obj->klass_or_null_acquire() == NULL)) {
-     return false;
-   }
- 
-   // We have a well-formed humongous object at the start of sr.
-   // Only filler objects follow a humongous object in the containing
-   // regions, and we can ignore those.  So only process the one
-   // humongous object.
-   if (!g1h->is_obj_dead(obj, sr)) {
-     if (obj->is_objArray() || (sr->bottom() < mr.start())) {
-       // objArrays are always marked precisely, so limit processing
-       // with mr.  Non-objArrays might be precisely marked, and since
-       // it's humongous it's worthwhile avoiding full processing.
-       // However, the card could be stale and only cover filler
-       // objects.  That should be rare, so not worth checking for;
-       // instead let it fall out from the bounded iteration.
-       obj->oop_iterate(cl, mr);
-     } else {
-       // If obj is not an objArray and mr contains the start of the
-       // obj, then this could be an imprecise mark, and we need to
-       // process the entire object.
-       obj->oop_iterate(cl);
-     }
-   }
-   return true;
- }
- 
- bool HeapRegion::oops_on_card_seq_iterate_careful(MemRegion mr,
-                                                   G1UpdateRSOrPushRefOopClosure* cl) {
-   assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
-   G1CollectedHeap* g1h = G1CollectedHeap::heap();
- 
-   // Special handling for humongous regions.
-   if (is_humongous()) {
-     return do_oops_on_card_in_humongous(mr, cl, this, g1h);
-   }
-   assert(is_old(), "precondition");
- 
-   // Because mr has been trimmed to what's been allocated in this
-   // region, the parts of the heap that are examined here are always
-   // parsable; there's no need to use klass_or_null to detect
-   // in-progress allocation.
- 
-   // Cache the boundaries of the memory region in some const locals
-   HeapWord* const start = mr.start();
-   HeapWord* const end = mr.end();
- 
-   // Find the obj that extends onto mr.start().
-   // Update BOT as needed while finding start of (possibly dead)
-   // object containing the start of the region.
-   HeapWord* cur = block_start(start);
- 
- #ifdef ASSERT
-   {
-     assert(cur <= start,
-            "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
-     HeapWord* next = cur + block_size(cur);
-     assert(start < next,
-            "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
-   }
- #endif
- 
-   do {
-     oop obj = oop(cur);
-     assert(obj->is_oop(true), "Not an oop at " PTR_FORMAT, p2i(cur));
-     assert(obj->klass_or_null() != NULL,
-            "Unparsable heap at " PTR_FORMAT, p2i(cur));
- 
-     if (g1h->is_obj_dead(obj, this)) {
-       // Carefully step over dead object.
-       cur += block_size(cur);
-     } else {
-       // Step over live object, and process its references.
-       cur += obj->size();
-       // Non-objArrays are usually marked imprecise at the object
-       // start, in which case we need to iterate over them in full.
-       // objArrays are precisely marked, but can still be iterated
-       // over in full if completely covered.
-       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
-         obj->oop_iterate(cl);
-       } else {
-         obj->oop_iterate(cl, mr);
-       }
-     }
-   } while (cur < end);
- 
-   return true;
- }
- 
  // Code roots support
  
  void HeapRegion::add_strong_code_root(nmethod* nm) {
    HeapRegionRemSet* hrrs = rem_set();
    hrrs->add_strong_code_root(nm);
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