8293210: G1: Remove redundant check in G1FreeHumongousRegionClosure

Reviewed-by: tschatzl, kbarrett

Author: albertnetymk

src/hotspot/share/gc/g1/g1CollectedHeap.inline.hpp

@@ -238,7 +238,6 @@ inline bool G1CollectedHeap::is_obj_dead_full(const oop obj) const {
 }
 
 inline bool G1CollectedHeap::is_humongous_reclaim_candidate(uint region) {
-  assert(_hrm.at(region)->is_starts_humongous(), "Must start a humongous object");
   return _region_attr.is_humongous_candidate(region);
 }
 

src/hotspot/share/gc/g1/g1YoungGCPostEvacuateTasks.cpp

@@ -137,10 +137,11 @@ G1PostEvacuateCollectionSetCleanupTask1::G1PostEvacuateCollectionSetCleanupTask1
   }
 }
 
-class G1FreeHumongousRegionClosure : public HeapRegionClosure {
+class G1FreeHumongousRegionClosure : public HeapRegionIndexClosure {
   uint _humongous_objects_reclaimed;
   uint _humongous_regions_reclaimed;
   size_t _freed_bytes;
+  G1CollectedHeap* _g1h;
 
   // Returns whether the given humongous object defined by the start region index
   // is reclaimable.
@@ -181,45 +182,42 @@ class G1FreeHumongousRegionClosure : public HeapRegionClosure {
   G1FreeHumongousRegionClosure() :
     _humongous_objects_reclaimed(0),
     _humongous_regions_reclaimed(0),
-    _freed_bytes(0) {
-  }
+    _freed_bytes(0),
+    _g1h(G1CollectedHeap::heap())
+  {}
 
-  virtual bool do_heap_region(HeapRegion* r) {
-    if (!r->is_starts_humongous()) {
+  bool do_heap_region_index(uint region_index) override {
+    if (!is_reclaimable(region_index)) {
       return false;
     }
 
-    uint region_idx = r->hrm_index();
-    if (!is_reclaimable(region_idx)) {
-      return false;
-    }
+    HeapRegion* r = _g1h->region_at(region_index);
 
     oop obj = cast_to_oop(r->bottom());
     guarantee(obj->is_typeArray(),
               "Only eagerly reclaiming type arrays is supported, but the object "
               PTR_FORMAT " is not.", p2i(r->bottom()));
 
     log_debug(gc, humongous)("Reclaimed humongous region %u (object size " SIZE_FORMAT " @ " PTR_FORMAT ")",
-                             region_idx,
+                             region_index,
                              obj->size() * HeapWordSize,
                              p2i(r->bottom())
                             );
 
-    G1CollectedHeap* g1h = G1CollectedHeap::heap();
-    G1ConcurrentMark* const cm = g1h->concurrent_mark();
+    G1ConcurrentMark* const cm = _g1h->concurrent_mark();
     cm->humongous_object_eagerly_reclaimed(r);
     assert(!cm->is_marked_in_bitmap(obj),
            "Eagerly reclaimed humongous region %u should not be marked at all but is in bitmap %s",
-           region_idx,
+           region_index,
            BOOL_TO_STR(cm->is_marked_in_bitmap(obj)));
     _humongous_objects_reclaimed++;
     do {
-      HeapRegion* next = g1h->next_region_in_humongous(r);
+      HeapRegion* next = _g1h->next_region_in_humongous(r);
       _freed_bytes += r->used();
       r->set_containing_set(nullptr);
       _humongous_regions_reclaimed++;
-      g1h->free_humongous_region(r, nullptr);
-      g1h->hr_printer()->cleanup(r);
+      _g1h->free_humongous_region(r, nullptr);
+      _g1h->hr_printer()->cleanup(r);
       r = next;
     } while (r != nullptr);