1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP
  26 #define SHARE_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP
  27 
  28 #include "gc/g1/g1CollectedHeap.inline.hpp"
  29 #include "gc/g1/g1OopStarChunkedList.inline.hpp"
  30 #include "gc/g1/g1ParScanThreadState.hpp"
  31 #include "gc/g1/g1RemSet.hpp"
  32 #include "oops/access.inline.hpp"
  33 #include "oops/oop.inline.hpp"
  34 
  35 template <class T> void G1ParScanThreadState::do_oop_evac(T* p) {
  36   // Reference should not be NULL here as such are never pushed to the task queue.
  37   oop obj = RawAccess<IS_NOT_NULL>::oop_load(p);
  38 
  39   // Although we never intentionally push references outside of the collection
  40   // set, due to (benign) races in the claim mechanism during RSet scanning more
  41   // than one thread might claim the same card. So the same card may be
  42   // processed multiple times, and so we might get references into old gen here.
  43   // So we need to redo this check.
  44   const G1HeapRegionAttr region_attr = _g1h->region_attr(obj);
  45   // References pushed onto the work stack should never point to a humongous region
  46   // as they are not added to the collection set due to above precondition.
  47   assert(!region_attr.is_humongous(),
  48          "Obj " PTR_FORMAT " should not refer to humongous region %u from " PTR_FORMAT,
  49          p2i(obj), _g1h->addr_to_region((HeapWord*)obj), p2i(p));
  50 
  51   if (!region_attr.is_in_cset()) {
  52     // In this case somebody else already did all the work.
  53     return;
  54   }
  55 
  56   markOop m = obj->mark_raw();
  57   if (m->is_marked()) {
  58     obj = (oop) m->decode_pointer();
  59   } else {
  60     obj = copy_to_survivor_space(region_attr, obj, m);
  61   }
  62   RawAccess<IS_NOT_NULL>::oop_store(p, obj);
  63 
  64   assert(obj != NULL, "Must be");
  65   if (HeapRegion::is_in_same_region(p, obj)) {
  66     return;
  67   }
  68   HeapRegion* from = _g1h->heap_region_containing(p);
  69   if (!from->is_young()) {
  70     enqueue_card_if_tracked(_g1h->region_attr(obj), p, obj);
  71   }
  72 }
  73 
  74 template <class T> inline void G1ParScanThreadState::push_on_queue(T* ref) {
  75   assert(verify_ref(ref), "sanity");
  76   _refs->push(ref);
  77 }
  78 
  79 inline void G1ParScanThreadState::do_oop_partial_array(oop* p) {
  80   assert(has_partial_array_mask(p), "invariant");
  81   oop from_obj = clear_partial_array_mask(p);
  82 
  83   assert(_g1h->is_in_reserved(from_obj), "must be in heap.");
  84   assert(from_obj->is_objArray(), "must be obj array");
  85   objArrayOop from_obj_array = objArrayOop(from_obj);
  86   // The from-space object contains the real length.
  87   int length                 = from_obj_array->length();
  88 
  89   assert(from_obj->is_forwarded(), "must be forwarded");
  90   oop to_obj                 = from_obj->forwardee();
  91   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
  92   objArrayOop to_obj_array   = objArrayOop(to_obj);
  93   // We keep track of the next start index in the length field of the
  94   // to-space object.
  95   int next_index             = to_obj_array->length();
  96   assert(0 <= next_index && next_index < length,
  97          "invariant, next index: %d, length: %d", next_index, length);
  98 
  99   int start                  = next_index;
 100   int end                    = length;
 101   int remainder              = end - start;
 102   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
 103   if (remainder > 2 * ParGCArrayScanChunk) {
 104     end = start + ParGCArrayScanChunk;
 105     to_obj_array->set_length(end);
 106     // Push the remainder before we process the range in case another
 107     // worker has run out of things to do and can steal it.
 108     oop* from_obj_p = set_partial_array_mask(from_obj);
 109     push_on_queue(from_obj_p);
 110   } else {
 111     assert(length == end, "sanity");
 112     // We'll process the final range for this object. Restore the length
 113     // so that the heap remains parsable in case of evacuation failure.
 114     to_obj_array->set_length(end);
 115   }
 116 
 117   HeapRegion* hr = _g1h->heap_region_containing(to_obj);
 118   G1ScanInYoungSetter x(&_scanner, hr->is_young());
 119   // Process indexes [start,end). It will also process the header
 120   // along with the first chunk (i.e., the chunk with start == 0).
 121   // Note that at this point the length field of to_obj_array is not
 122   // correct given that we are using it to keep track of the next
 123   // start index. oop_iterate_range() (thankfully!) ignores the length
 124   // field and only relies on the start / end parameters.  It does
 125   // however return the size of the object which will be incorrect. So
 126   // we have to ignore it even if we wanted to use it.
 127   to_obj_array->oop_iterate_range(&_scanner, start, end);
 128 }
 129 
 130 inline void G1ParScanThreadState::deal_with_reference(oop* ref_to_scan) {
 131   if (!has_partial_array_mask(ref_to_scan)) {
 132     do_oop_evac(ref_to_scan);
 133   } else {
 134     do_oop_partial_array(ref_to_scan);
 135   }
 136 }
 137 
 138 inline void G1ParScanThreadState::deal_with_reference(narrowOop* ref_to_scan) {
 139   assert(!has_partial_array_mask(ref_to_scan), "NarrowOop* elements should never be partial arrays.");
 140   do_oop_evac(ref_to_scan);
 141 }
 142 
 143 inline void G1ParScanThreadState::dispatch_reference(StarTask ref) {
 144   assert(verify_task(ref), "sanity");
 145   if (ref.is_narrow()) {
 146     deal_with_reference((narrowOop*)ref);
 147   } else {
 148     deal_with_reference((oop*)ref);
 149   }
 150 }
 151 
 152 void G1ParScanThreadState::steal_and_trim_queue(RefToScanQueueSet *task_queues) {
 153   StarTask stolen_task;
 154   while (task_queues->steal(_worker_id, stolen_task)) {
 155     assert(verify_task(stolen_task), "sanity");
 156     dispatch_reference(stolen_task);
 157 
 158     // We've just processed a reference and we might have made
 159     // available new entries on the queues. So we have to make sure
 160     // we drain the queues as necessary.
 161     trim_queue();
 162   }
 163 }
 164 
 165 inline bool G1ParScanThreadState::needs_partial_trimming() const {
 166   return !_refs->overflow_empty() || _refs->size() > _stack_trim_upper_threshold;
 167 }
 168 
 169 inline bool G1ParScanThreadState::is_partially_trimmed() const {
 170   return _refs->overflow_empty() && _refs->size() <= _stack_trim_lower_threshold;
 171 }
 172 
 173 inline void G1ParScanThreadState::trim_queue_to_threshold(uint threshold) {
 174   StarTask ref;
 175   // Drain the overflow stack first, so other threads can potentially steal.
 176   while (_refs->pop_overflow(ref)) {
 177     if (!_refs->try_push_to_taskqueue(ref)) {
 178       dispatch_reference(ref);
 179     }
 180   }
 181 
 182   while (_refs->pop_local(ref, threshold)) {
 183     dispatch_reference(ref);
 184   }
 185 }
 186 
 187 inline void G1ParScanThreadState::trim_queue_partially() {
 188   if (!needs_partial_trimming()) {
 189     return;
 190   }
 191 
 192   const Ticks start = Ticks::now();
 193   do {
 194     trim_queue_to_threshold(_stack_trim_lower_threshold);
 195   } while (!is_partially_trimmed());
 196   _trim_ticks += Ticks::now() - start;
 197 }
 198 
 199 inline Tickspan G1ParScanThreadState::trim_ticks() const {
 200   return _trim_ticks;
 201 }
 202 
 203 inline void G1ParScanThreadState::reset_trim_ticks() {
 204   _trim_ticks = Tickspan();
 205 }
 206 
 207 template <typename T>
 208 inline void G1ParScanThreadState::remember_root_into_optional_region(T* p) {
 209   oop o = RawAccess<IS_NOT_NULL>::oop_load(p);
 210   uint index = _g1h->heap_region_containing(o)->index_in_opt_cset();
 211   assert(index < _num_optional_regions,
 212          "Trying to access optional region idx %u beyond " SIZE_FORMAT, index, _num_optional_regions);
 213   _oops_into_optional_regions[index].push_root(p);
 214 }
 215 
 216 template <typename T>
 217 inline void G1ParScanThreadState::remember_reference_into_optional_region(T* p) {
 218   oop o = RawAccess<IS_NOT_NULL>::oop_load(p);
 219   uint index = _g1h->heap_region_containing(o)->index_in_opt_cset();
 220   assert(index < _num_optional_regions,
 221          "Trying to access optional region idx %u beyond " SIZE_FORMAT, index, _num_optional_regions);
 222   _oops_into_optional_regions[index].push_oop(p);
 223   DEBUG_ONLY(verify_ref(p);)
 224 }
 225 
 226 G1OopStarChunkedList* G1ParScanThreadState::oops_into_optional_region(const HeapRegion* hr) {
 227   assert(hr->index_in_opt_cset() < _num_optional_regions,
 228          "Trying to access optional region idx %u beyond " SIZE_FORMAT " " HR_FORMAT,
 229          hr->index_in_opt_cset(), _num_optional_regions, HR_FORMAT_PARAMS(hr));
 230   return &_oops_into_optional_regions[hr->index_in_opt_cset()];
 231 }
 232 
 233 #endif // SHARE_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP