8253600: G1: Fully support pinned regions for full gc

Reviewed-by: sjohanss, ayang

Author: Thomas Schatzl

src/hotspot/share/gc/g1/g1Allocator.cpp

@@ -398,15 +398,8 @@ size_t G1PLABAllocator::undo_waste() const {
   return result;
 }
 
-bool G1ArchiveAllocator::_archive_check_enabled = false;
-G1ArchiveRegionMap G1ArchiveAllocator::_archive_region_map;
-
 G1ArchiveAllocator* G1ArchiveAllocator::create_allocator(G1CollectedHeap* g1h, bool open) {
-  // Create the archive allocator, and also enable archive object checking
-  // in mark-sweep, since we will be creating archive regions.
-  G1ArchiveAllocator* result =  new G1ArchiveAllocator(g1h, open);
-  enable_archive_object_check();
-  return result;
+  return new G1ArchiveAllocator(g1h, open);
 }
 
 bool G1ArchiveAllocator::alloc_new_region() {
@@ -434,9 +427,6 @@ bool G1ArchiveAllocator::alloc_new_region() {
   _bottom = hr->bottom();
   _max = _bottom + HeapRegion::min_region_size_in_words();
 
-  // Tell mark-sweep that objects in this region are not to be marked.
-  set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), _open);
-
   // Since we've modified the old set, call update_sizes.
   _g1h->g1mm()->update_sizes();
   return true;

src/hotspot/share/gc/g1/g1Allocator.hpp

@@ -192,19 +192,6 @@ class G1PLABAllocator : public CHeapObj<mtGC> {
   void undo_allocation(G1HeapRegionAttr dest, HeapWord* obj, size_t word_sz, uint node_index);
 };
 
-// G1ArchiveRegionMap is an array used to mark G1 regions as
-// archive regions.  This allows a quick check for whether an object
-// should not be marked because it is in an archive region.
-class G1ArchiveRegionMap : public G1BiasedMappedArray<uint8_t> {
-public:
-  static const uint8_t NoArchive = 0;
-  static const uint8_t OpenArchive = 1;
-  static const uint8_t ClosedArchive = 2;
-
-protected:
-  uint8_t default_value() const { return NoArchive; }
-};
-
 // G1ArchiveAllocator is used to allocate memory in archive
 // regions. Such regions are not scavenged nor compacted by GC.
 // There are two types of archive regions, which are
@@ -278,33 +265,6 @@ class G1ArchiveAllocator : public CHeapObj<mtGC> {
   void clear_used() {
     _summary_bytes_used = 0;
   }
-
-  // Create the _archive_region_map which is used to identify archive objects.
-  static inline void enable_archive_object_check();
-
-  // Mark regions containing the specified address range as archive/non-archive.
-  static inline void set_range_archive(MemRegion range, bool open);
-  static inline void clear_range_archive(MemRegion range);
-
-  // Check if the object is in closed archive
-  static inline bool is_closed_archive_object(oop object);
-  // Check if the object is in open archive
-  static inline bool is_open_archive_object(oop object);
-  // Check if the object is either in closed archive or open archive
-  static inline bool is_archived_object(oop object);
-
-private:
-  static bool _archive_check_enabled;
-  static G1ArchiveRegionMap  _archive_region_map;
-
-  // Check if an object is in a closed archive region using the _closed_archive_region_map.
-  static inline bool in_closed_archive_range(oop object);
-  // Check if an object is in open archive region using the _open_archive_region_map.
-  static inline bool in_open_archive_range(oop object);
-
-  // Check if archive object checking is enabled, to avoid calling in_open/closed_archive_range
-  // unnecessarily.
-  static inline bool archive_check_enabled();
 };
 
 #endif // SHARE_GC_G1_G1ALLOCATOR_HPP

src/hotspot/share/gc/g1/g1Allocator.inline.hpp

@@ -119,63 +119,4 @@ inline HeapWord* G1PLABAllocator::allocate(G1HeapRegionAttr dest,
   return allocate_direct_or_new_plab(dest, word_sz, refill_failed, node_index);
 }
 
-// Create the maps which is used to identify archive objects.
-inline void G1ArchiveAllocator::enable_archive_object_check() {
-  if (_archive_check_enabled) {
-    return;
-  }
-
-  _archive_check_enabled = true;
-  _archive_region_map.initialize(G1CollectedHeap::heap()->reserved(),
-                                 HeapRegion::GrainBytes);
-}
-
-// Set the regions containing the specified address range as archive.
-inline void G1ArchiveAllocator::set_range_archive(MemRegion range, bool open) {
-  assert(_archive_check_enabled, "archive range check not enabled");
-  log_info(gc, cds)("Mark %s archive regions in map: [" PTR_FORMAT ", " PTR_FORMAT "]",
-                     open ? "open" : "closed",
-                     p2i(range.start()),
-                     p2i(range.last()));
-  uint8_t const value = open ? G1ArchiveRegionMap::OpenArchive : G1ArchiveRegionMap::ClosedArchive;
-  _archive_region_map.set_by_address(range, value);
-}
-
-// Clear the archive regions map containing the specified address range.
-inline void G1ArchiveAllocator::clear_range_archive(MemRegion range) {
-  assert(_archive_check_enabled, "archive range check not enabled");
-  log_info(gc, cds)("Clear archive regions in map: [" PTR_FORMAT ", " PTR_FORMAT "]",
-                    p2i(range.start()),
-                    p2i(range.last()));
-  _archive_region_map.set_by_address(range, G1ArchiveRegionMap::NoArchive);
-}
-
-// Check if an object is in a closed archive region using the _archive_region_map.
-inline bool G1ArchiveAllocator::in_closed_archive_range(oop object) {
-  return _archive_region_map.get_by_address(cast_from_oop<HeapWord*>(object)) == G1ArchiveRegionMap::ClosedArchive;
-}
-
-inline bool G1ArchiveAllocator::in_open_archive_range(oop object) {
-  return _archive_region_map.get_by_address(cast_from_oop<HeapWord*>(object)) == G1ArchiveRegionMap::OpenArchive;
-}
-
-// Check if archive object checking is enabled, to avoid calling in_open/closed_archive_range
-// unnecessarily.
-inline bool G1ArchiveAllocator::archive_check_enabled() {
-  return _archive_check_enabled;
-}
-
-inline bool G1ArchiveAllocator::is_closed_archive_object(oop object) {
-  return (archive_check_enabled() && in_closed_archive_range(object));
-}
-
-inline bool G1ArchiveAllocator::is_open_archive_object(oop object) {
-  return (archive_check_enabled() && in_open_archive_range(object));
-}
-
-inline bool G1ArchiveAllocator::is_archived_object(oop object) {
-  return archive_check_enabled() &&
-         (_archive_region_map.get_by_address(cast_from_oop<HeapWord*>(object)) != G1ArchiveRegionMap::NoArchive);
-}
-
 #endif // SHARE_GC_G1_G1ALLOCATOR_INLINE_HPP

src/hotspot/share/gc/g1/g1CollectedHeap.cpp

@@ -570,10 +570,6 @@ bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
   // when mmap'ing archived heap data in, so pre-touching is wasted.
   FlagSetting fs(AlwaysPreTouch, false);
 
-  // Enable archive object checking used by G1MarkSweep. We have to let it know
-  // about each archive range, so that objects in those ranges aren't marked.
-  G1ArchiveAllocator::enable_archive_object_check();
-
   // For each specified MemRegion range, allocate the corresponding G1
   // regions and mark them as archive regions. We expect the ranges
   // in ascending starting address order, without overlap.
@@ -649,9 +645,6 @@ bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
       curr_region->set_top(top);
       curr_region = next_region;
     }
-
-    // Notify mark-sweep of the archive
-    G1ArchiveAllocator::set_range_archive(curr_range, open);
   }
   return true;
 }
@@ -802,9 +795,6 @@ void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
       _hrm->shrink_at(curr_index, 1);
       uncommitted_regions++;
     }
-
-    // Notify mark-sweep that this is no longer an archive range.
-    G1ArchiveAllocator::clear_range_archive(ranges[i]);
   }
 
   if (uncommitted_regions != 0) {
@@ -815,8 +805,7 @@ void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
 }
 
 oop G1CollectedHeap::materialize_archived_object(oop obj) {
-  assert(obj != NULL, "archived obj is NULL");
-  assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
+  assert(is_archived_object(obj), "not an archived obj");
 
   // Loading an archived object makes it strongly reachable. If it is
   // loaded during concurrent marking, it must be enqueued to the SATB
@@ -1016,8 +1005,7 @@ void G1CollectedHeap::prepare_heap_for_full_collection() {
   // after this full GC.
   abandon_collection_set(collection_set());
 
-  tear_down_region_sets(false /* free_list_only */);
-
+  hrm()->remove_all_free_regions();
   hrm()->prepare_for_full_collection_start();
 }
 
@@ -1073,17 +1061,7 @@ void G1CollectedHeap::verify_after_full_collection() {
   _hrm->verify_optional();
   _verifier->verify_region_sets_optional();
   _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
-  // Clear the previous marking bitmap, if needed for bitmap verification.
-  // Note we cannot do this when we clear the next marking bitmap in
-  // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
-  // objects marked during a full GC against the previous bitmap.
-  // But we need to clear it before calling check_bitmaps below since
-  // the full GC has compacted objects and updated TAMS but not updated
-  // the prev bitmap.
-  if (G1VerifyBitmaps) {
-    GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
-    _cm->clear_prev_bitmap(workers());
-  }
+
   // This call implicitly verifies that the next bitmap is clear after Full GC.
   _verifier->check_bitmaps("Full GC End");
 
@@ -1347,7 +1325,7 @@ void G1CollectedHeap::shrink(size_t shrink_bytes) {
   // Instead of tearing down / rebuilding the free lists here, we
   // could instead use the remove_all_pending() method on free_list to
   // remove only the ones that we need to remove.
-  tear_down_region_sets(true /* free_list_only */);
+  hrm()->remove_all_free_regions();
   shrink_helper(shrink_bytes);
   rebuild_region_sets(true /* free_list_only */);
 
@@ -2395,6 +2373,10 @@ bool G1CollectedHeap::is_heterogeneous_heap() const {
   return G1Arguments::is_heterogeneous_heap();
 }
 
+bool G1CollectedHeap::is_archived_object(oop object) const {
+  return object != NULL && heap_region_containing(object)->is_archive();
+}
+
 class PrintRegionClosure: public HeapRegionClosure {
   outputStream* _st;
 public:
@@ -4565,45 +4547,23 @@ bool G1CollectedHeap::check_young_list_empty() {
 
 #endif // ASSERT
 
-class TearDownRegionSetsClosure : public HeapRegionClosure {
-  HeapRegionSet *_old_set;
-
-public:
-  TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
-
-  bool do_heap_region(HeapRegion* r) {
-    if (r->is_old()) {
-      _old_set->remove(r);
-    } else if(r->is_young()) {
-      r->uninstall_surv_rate_group();
-    } else {
-      // We ignore free regions, we'll empty the free list afterwards.
-      // We ignore humongous and archive regions, we're not tearing down these
-      // sets.
-      assert(r->is_archive() || r->is_free() || r->is_humongous(),
-             "it cannot be another type");
-    }
-    return false;
-  }
-
-  ~TearDownRegionSetsClosure() {
-    assert(_old_set->is_empty(), "post-condition");
-  }
-};
-
-void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
-  assert_at_safepoint_on_vm_thread();
-
-  if (!free_list_only) {
-    TearDownRegionSetsClosure cl(&_old_set);
-    heap_region_iterate(&cl);
-
+  // Remove the given HeapRegion from the appropriate region set.
+void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
+  if (hr->is_old()) {
+    _old_set.remove(hr);
+  } else if (hr->is_young()) {
     // Note that emptying the _young_list is postponed and instead done as
     // the first step when rebuilding the regions sets again. The reason for
     // this is that during a full GC string deduplication needs to know if
     // a collected region was young or old when the full GC was initiated.
+    hr->uninstall_surv_rate_group();
+  } else {
+    // We ignore free regions, we'll empty the free list afterwards.
+    // We ignore humongous and archive regions, we're not tearing down these
+    // sets.
+    assert(hr->is_archive() || hr->is_free() || hr->is_humongous(),
+           "it cannot be another type");
   }
-  _hrm->remove_all_free_regions();
 }
 
 void G1CollectedHeap::increase_used(size_t bytes) {

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

@@ -177,20 +177,14 @@ class G1CollectedHeap : public CollectedHeap {
   // The block offset table for the G1 heap.
   G1BlockOffsetTable* _bot;
 
-  // Tears down the region sets / lists so that they are empty and the
-  // regions on the heap do not belong to a region set / list. The
-  // only exception is the humongous set which we leave unaltered. If
-  // free_list_only is true, it will only tear down the master free
-  // list. It is called before a Full GC (free_list_only == false) or
-  // before heap shrinking (free_list_only == true).
-  void tear_down_region_sets(bool free_list_only);
+public:
+  void prepare_region_for_full_compaction(HeapRegion* hr);
 
+private:
   // Rebuilds the region sets / lists so that they are repopulated to
   // reflect the contents of the heap. The only exception is the
   // humongous set which was not torn down in the first place. If
-  // free_list_only is true, it will only rebuild the master free
-  // list. It is called after a Full GC (free_list_only == false) or
-  // after heap shrinking (free_list_only == true).
+  // free_list_only is true, it will only rebuild the free list.
   void rebuild_region_sets(bool free_list_only);
 
   // Callback for region mapping changed events.
@@ -1424,6 +1418,8 @@ class G1CollectedHeap : public CollectedHeap {
 
   virtual WorkGang* safepoint_workers() { return _workers; }
 
+  virtual bool is_archived_object(oop object) const;
+
   // The methods below are here for convenience and dispatch the
   // appropriate method depending on value of the given VerifyOption
   // parameter. The values for that parameter, and their meanings,

src/hotspot/share/gc/g1/g1CollectionSetCandidates.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -54,7 +54,12 @@ void G1CollectionSetCandidates::verify() const {
   for (; idx < _num_regions; idx++) {
     HeapRegion *cur = _regions[idx];
     guarantee(cur != NULL, "Regions after _front_idx %u cannot be NULL but %u is", _front_idx, idx);
-    guarantee(G1CollectionSetChooser::should_add(cur), "Region %u should be eligible for addition.", cur->hrm_index());
+    // The first disjunction filters out regions with objects that were explicitly
+    // pinned after being added to the collection set candidates. Archive regions
+    // should never have been added to the collection set though.
+    guarantee((cur->is_pinned() && !cur->is_archive()) ||
+              G1CollectionSetChooser::should_add(cur),
+              "Region %u should be eligible for addition.", cur->hrm_index());
     if (prev != NULL) {
       guarantee(prev->gc_efficiency() >= cur->gc_efficiency(),
                 "GC efficiency for region %u: %1.4f smaller than for region %u: %1.4f",

src/hotspot/share/gc/g1/g1ConcurrentMark.cpp

@@ -675,9 +675,9 @@ void G1ConcurrentMark::cleanup_for_next_mark() {
   guarantee(!_g1h->collector_state()->mark_or_rebuild_in_progress(), "invariant");
 }
 
-void G1ConcurrentMark::clear_prev_bitmap(WorkGang* workers) {
+void G1ConcurrentMark::clear_next_bitmap(WorkGang* workers) {
   assert_at_safepoint_on_vm_thread();
-  clear_bitmap(_prev_mark_bitmap, workers, false);
+  clear_bitmap(_next_mark_bitmap, workers, false);
 }
 
 class NoteStartOfMarkHRClosure : public HeapRegionClosure {
@@ -1132,6 +1132,8 @@ void G1ConcurrentMark::remark() {
 
     // Install newly created mark bitmap as "prev".
     swap_mark_bitmaps();
+
+    _g1h->collector_state()->set_clearing_next_bitmap(true);
     {
       GCTraceTime(Debug, gc, phases) debug("Update Remembered Set Tracking Before Rebuild", _gc_timer_cm);
 
@@ -1696,7 +1698,6 @@ void G1ConcurrentMark::swap_mark_bitmaps() {
   G1CMBitMap* temp = _prev_mark_bitmap;
   _prev_mark_bitmap = _next_mark_bitmap;
   _next_mark_bitmap = temp;
-  _g1h->collector_state()->set_clearing_next_bitmap(true);
 }
 
 // Closure for marking entries in SATB buffers.
@@ -1975,7 +1976,7 @@ void G1ConcurrentMark::concurrent_cycle_abort() {
   // concurrent bitmap clearing.
   {
     GCTraceTime(Debug, gc) debug("Clear Next Bitmap");
-    clear_bitmap(_next_mark_bitmap, _g1h->workers(), false);
+    clear_next_bitmap(_g1h->workers());
   }
   // Note we cannot clear the previous marking bitmap here
   // since VerifyDuringGC verifies the objects marked during