/*

 * Copyright (c) 2000, 2014, 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

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "memory/allocation.inline.hpp"

#include "memory/cardTableModRefBS.hpp"

#include "memory/cardTableRS.hpp"

#include "memory/sharedHeap.hpp"

#include "memory/space.hpp"

#include "memory/space.inline.hpp"

#include "memory/universe.hpp"

#include "runtime/java.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/virtualspace.hpp"

#include "services/memTracker.hpp"

#include "utilities/macros.hpp"

#ifdef COMPILER1

#include "c1/c1_LIR.hpp"

#include "c1/c1_LIRGenerator.hpp"

#endif

// This kind of "BarrierSet" allows a "CollectedHeap" to detect and

// enumerate ref fields that have been modified (since the last

// enumeration.)

size_t CardTableModRefBS::compute_byte_map_size()

{

  assert(_guard_index == cards_required(_whole_heap.word_size()) - 1,

                                        "uninitialized, check declaration order");

  assert(_page_size != 0, "uninitialized, check declaration order");

  const size_t granularity = os::vm_allocation_granularity();

  return align_size_up(_guard_index + 1, MAX2(_page_size, granularity));

}

CardTableModRefBS::CardTableModRefBS(MemRegion whole_heap,

                                     int max_covered_regions):

  ModRefBarrierSet(max_covered_regions),

  _whole_heap(whole_heap),

  _guard_index(0),

  _guard_region(),

  _last_valid_index(0),

  _page_size(os::vm_page_size()),

  _byte_map_size(0),

  _covered(NULL),

  _committed(NULL),

  _cur_covered_regions(0),

  _byte_map(NULL),

  byte_map_base(NULL),

  // LNC functionality

  _lowest_non_clean(NULL),

  _lowest_non_clean_chunk_size(NULL),

  _lowest_non_clean_base_chunk_index(NULL),

  _last_LNC_resizing_collection(NULL)

{

  _kind = BarrierSet::CardTableModRef;

  assert((uintptr_t(_whole_heap.start())  & (card_size - 1))  == 0, "heap must start at card boundary");

  assert((uintptr_t(_whole_heap.end()) & (card_size - 1))  == 0, "heap must end at card boundary");

  assert(card_size <= 512, "card_size must be less than 512"); // why?

  _covered   = new MemRegion[_max_covered_regions];

  if (_covered == NULL) {

    vm_exit_during_initialization("Could not allocate card table covered region set.");

  }

}

void CardTableModRefBS::initialize() {

  _guard_index = cards_required(_whole_heap.word_size()) - 1;

  _last_valid_index = _guard_index - 1;

  _byte_map_size = compute_byte_map_size();

  HeapWord* low_bound  = _whole_heap.start();

  HeapWord* high_bound = _whole_heap.end();

  _cur_covered_regions = 0;

  _committed = new MemRegion[_max_covered_regions];

  if (_committed == NULL) {

    vm_exit_during_initialization("Could not allocate card table committed region set.");

  }

  const size_t rs_align = _page_size == (size_t) os::vm_page_size() ? 0 :

    MAX2(_page_size, (size_t) os::vm_allocation_granularity());

  ReservedSpace heap_rs(_byte_map_size, rs_align, false);

  MemTracker::record_virtual_memory_type((address)heap_rs.base(), mtGC);

  os::trace_page_sizes("card table", _guard_index + 1, _guard_index + 1,

                       _page_size, heap_rs.base(), heap_rs.size());

  if (!heap_rs.is_reserved()) {

    vm_exit_during_initialization("Could not reserve enough space for the "

                                  "card marking array");

  }

  // The assembler store_check code will do an unsigned shift of the oop,

  // then add it to byte_map_base, i.e.

  //

  //   _byte_map = byte_map_base + (uintptr_t(low_bound) >> card_shift)

  _byte_map = (jbyte*) heap_rs.base();

  byte_map_base = _byte_map - (uintptr_t(low_bound) >> card_shift);

  assert(byte_for(low_bound) == &_byte_map[0], "Checking start of map");

  assert(byte_for(high_bound-1) <= &_byte_map[_last_valid_index], "Checking end of map");

  jbyte* guard_card = &_byte_map[_guard_index];

  uintptr_t guard_page = align_size_down((uintptr_t)guard_card, _page_size);

  _guard_region = MemRegion((HeapWord*)guard_page, _page_size);

  os::commit_memory_or_exit((char*)guard_page, _page_size, _page_size,

                            !ExecMem, "card table last card");

  *guard_card = last_card;

  _lowest_non_clean =

    NEW_C_HEAP_ARRAY(CardArr, _max_covered_regions, mtGC);

  _lowest_non_clean_chunk_size =

    NEW_C_HEAP_ARRAY(size_t, _max_covered_regions, mtGC);

  _lowest_non_clean_base_chunk_index =

    NEW_C_HEAP_ARRAY(uintptr_t, _max_covered_regions, mtGC);

  _last_LNC_resizing_collection =

    NEW_C_HEAP_ARRAY(int, _max_covered_regions, mtGC);

  if (_lowest_non_clean == NULL

      || _lowest_non_clean_chunk_size == NULL

      || _lowest_non_clean_base_chunk_index == NULL

      || _last_LNC_resizing_collection == NULL)

    vm_exit_during_initialization("couldn't allocate an LNC array.");

  for (int i = 0; i < _max_covered_regions; i++) {

    _lowest_non_clean[i] = NULL;

    _lowest_non_clean_chunk_size[i] = 0;

    _last_LNC_resizing_collection[i] = -1;

  }

  if (TraceCardTableModRefBS) {

    gclog_or_tty->print_cr("CardTableModRefBS::CardTableModRefBS: ");

    gclog_or_tty->print_cr("  "

                  "  &_byte_map[0]: " INTPTR_FORMAT

                  "  &_byte_map[_last_valid_index]: " INTPTR_FORMAT,

                  p2i(&_byte_map[0]),

                  p2i(&_byte_map[_last_valid_index]));

    gclog_or_tty->print_cr("  "

                  "  byte_map_base: " INTPTR_FORMAT,

                  p2i(byte_map_base));

  }

}

CardTableModRefBS::~CardTableModRefBS() {

  if (_covered) {

    delete[] _covered;

    _covered = NULL;

  }

  if (_committed) {

    delete[] _committed;

    _committed = NULL;

  }

  if (_lowest_non_clean) {

    FREE_C_HEAP_ARRAY(CardArr, _lowest_non_clean, mtGC);

    _lowest_non_clean = NULL;

  }

  if (_lowest_non_clean_chunk_size) {

    FREE_C_HEAP_ARRAY(size_t, _lowest_non_clean_chunk_size, mtGC);

    _lowest_non_clean_chunk_size = NULL;

  }

  if (_lowest_non_clean_base_chunk_index) {

    FREE_C_HEAP_ARRAY(uintptr_t, _lowest_non_clean_base_chunk_index, mtGC);

    _lowest_non_clean_base_chunk_index = NULL;

  }

  if (_last_LNC_resizing_collection) {

    FREE_C_HEAP_ARRAY(int, _last_LNC_resizing_collection, mtGC);

    _last_LNC_resizing_collection = NULL;

  }

}

int CardTableModRefBS::find_covering_region_by_base(HeapWord* base) {

  int i;

  for (i = 0; i < _cur_covered_regions; i++) {

    if (_covered[i].start() == base) return i;

    if (_covered[i].start() > base) break;

  }

  // If we didn't find it, create a new one.

  assert(_cur_covered_regions < _max_covered_regions,

         "too many covered regions");

  // Move the ones above up, to maintain sorted order.

  for (int j = _cur_covered_regions; j > i; j--) {

    _covered[j] = _covered[j-1];

    _committed[j] = _committed[j-1];

  }

  int res = i;

  _cur_covered_regions++;

  _covered[res].set_start(base);

  _covered[res].set_word_size(0);

  jbyte* ct_start = byte_for(base);

  uintptr_t ct_start_aligned = align_size_down((uintptr_t)ct_start, _page_size);

  _committed[res].set_start((HeapWord*)ct_start_aligned);

  _committed[res].set_word_size(0);

  return res;

}

int CardTableModRefBS::find_covering_region_containing(HeapWord* addr) {

  for (int i = 0; i < _cur_covered_regions; i++) {

    if (_covered[i].contains(addr)) {

      return i;

    }

  }

  assert(0, "address outside of heap?");

  return -1;

}

HeapWord* CardTableModRefBS::largest_prev_committed_end(int ind) const {

  HeapWord* max_end = NULL;

  for (int j = 0; j < ind; j++) {

    HeapWord* this_end = _committed[j].end();

    if (this_end > max_end) max_end = this_end;

  }

  return max_end;

}

MemRegion CardTableModRefBS::committed_unique_to_self(int self,

                                                      MemRegion mr) const {

  MemRegion result = mr;

  for (int r = 0; r < _cur_covered_regions; r += 1) {

    if (r != self) {

      result = result.minus(_committed[r]);

    }

  }

  // Never include the guard page.

  result = result.minus(_guard_region);

  return result;

}

void CardTableModRefBS::resize_covered_region(MemRegion new_region) {

  // We don't change the start of a region, only the end.

  assert(_whole_heap.contains(new_region),

           "attempt to cover area not in reserved area");

  debug_only(verify_guard();)

  // collided is true if the expansion would push into another committed region

  debug_only(bool collided = false;)

  int const ind = find_covering_region_by_base(new_region.start());

  MemRegion const old_region = _covered[ind];

  assert(old_region.start() == new_region.start(), "just checking");

  if (new_region.word_size() != old_region.word_size()) {

    // Commit new or uncommit old pages, if necessary.

    MemRegion cur_committed = _committed[ind];

    // Extend the end of this _committed region

    // to cover the end of any lower _committed regions.

    // This forms overlapping regions, but never interior regions.

    HeapWord* const max_prev_end = largest_prev_committed_end(ind);

    if (max_prev_end > cur_committed.end()) {

      cur_committed.set_end(max_prev_end);

    }

    // Align the end up to a page size (starts are already aligned).

    jbyte* const new_end = byte_after(new_region.last());

    HeapWord* new_end_aligned =

      (HeapWord*) align_size_up((uintptr_t)new_end, _page_size);

    assert(new_end_aligned >= (HeapWord*) new_end,

           "align up, but less");

    // Check the other regions (excludes "ind") to ensure that

    // the new_end_aligned does not intrude onto the committed

    // space of another region.

    int ri = 0;

    for (ri = 0; ri < _cur_covered_regions; ri++) {

      if (ri != ind) {

        if (_committed[ri].contains(new_end_aligned)) {

          // The prior check included in the assert

          // (new_end_aligned >= _committed[ri].start())

          // is redundant with the "contains" test.

          // Any region containing the new end

          // should start at or beyond the region found (ind)

          // for the new end (committed regions are not expected to

          // be proper subsets of other committed regions).

          assert(_committed[ri].start() >= _committed[ind].start(),

                 "New end of committed region is inconsistent");

          new_end_aligned = _committed[ri].start();

          // new_end_aligned can be equal to the start of its

          // committed region (i.e., of "ind") if a second

          // region following "ind" also start at the same location

          // as "ind".

          assert(new_end_aligned >= _committed[ind].start(),

            "New end of committed region is before start");

          debug_only(collided = true;)

          // Should only collide with 1 region

          break;

        }

      }

    }

#ifdef ASSERT

    for (++ri; ri < _cur_covered_regions; ri++) {

      assert(!_committed[ri].contains(new_end_aligned),

        "New end of committed region is in a second committed region");

    }

#endif

    // The guard page is always committed and should not be committed over.

    // "guarded" is used for assertion checking below and recalls the fact

    // that the would-be end of the new committed region would have

    // penetrated the guard page.

    HeapWord* new_end_for_commit = new_end_aligned;

    DEBUG_ONLY(bool guarded = false;)

    if (new_end_for_commit > _guard_region.start()) {

      new_end_for_commit = _guard_region.start();

      DEBUG_ONLY(guarded = true;)

    }

    if (new_end_for_commit > cur_committed.end()) {

      // Must commit new pages.

      MemRegion const new_committed =

        MemRegion(cur_committed.end(), new_end_for_commit);

      assert(!new_committed.is_empty(), "Region should not be empty here");

      os::commit_memory_or_exit((char*)new_committed.start(),

                                new_committed.byte_size(), _page_size,

                                !ExecMem, "card table expansion");

    // Use new_end_aligned (as opposed to new_end_for_commit) because

    // the cur_committed region may include the guard region.

    } else if (new_end_aligned < cur_committed.end()) {

      // Must uncommit pages.

      MemRegion const uncommit_region =

        committed_unique_to_self(ind, MemRegion(new_end_aligned,

                                                cur_committed.end()));

      if (!uncommit_region.is_empty()) {

        // It is not safe to uncommit cards if the boundary between

        // the generations is moving.  A shrink can uncommit cards

        // owned by generation A but being used by generation B.

        if (!UseAdaptiveGCBoundary) {

          if (!os::uncommit_memory((char*)uncommit_region.start(),

                                   uncommit_region.byte_size())) {

            assert(false, "Card table contraction failed");

            // The call failed so don't change the end of the

            // committed region.  This is better than taking the

            // VM down.

            new_end_aligned = _committed[ind].end();

          }

        } else {

          new_end_aligned = _committed[ind].end();

        }

      }

    }

    // In any case, we can reset the end of the current committed entry.

    _committed[ind].set_end(new_end_aligned);

#ifdef ASSERT

    // Check that the last card in the new region is committed according

    // to the tables.

    bool covered = false;

    for (int cr = 0; cr < _cur_covered_regions; cr++) {

      if (_committed[cr].contains(new_end - 1)) {

        covered = true;

        break;

      }

    }

    assert(covered, "Card for end of new region not committed");

#endif

    // The default of 0 is not necessarily clean cards.

    jbyte* entry;

    if (old_region.last() < _whole_heap.start()) {

      entry = byte_for(_whole_heap.start());

    } else {

      entry = byte_after(old_region.last());

    }

    assert(index_for(new_region.last()) <  _guard_index,

      "The guard card will be overwritten");

    // This line commented out cleans the newly expanded region and

    // not the aligned up expanded region.

    // jbyte* const end = byte_after(new_region.last());

    jbyte* const end = (jbyte*) new_end_for_commit;

    assert((end >= byte_after(new_region.last())) || collided || guarded,

      "Expect to be beyond new region unless impacting another region");

    // do nothing if we resized downward.

#ifdef ASSERT

    for (int ri = 0; ri < _cur_covered_regions; ri++) {

      if (ri != ind) {

        // The end of the new committed region should not

        // be in any existing region unless it matches

        // the start of the next region.

        assert(!_committed[ri].contains(end) ||

               (_committed[ri].start() == (HeapWord*) end),

               "Overlapping committed regions");

      }

    }

#endif

    if (entry < end) {

      memset(entry, clean_card, pointer_delta(end, entry, sizeof(jbyte)));

    }

  }

  // In any case, the covered size changes.

  _covered[ind].set_word_size(new_region.word_size());

  if (TraceCardTableModRefBS) {

    gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: ");

    gclog_or_tty->print_cr("  "

                  "  _covered[%d].start(): " INTPTR_FORMAT

                  "  _covered[%d].last(): " INTPTR_FORMAT,

                  ind, p2i(_covered[ind].start()),

                  ind, p2i(_covered[ind].last()));

    gclog_or_tty->print_cr("  "

                  "  _committed[%d].start(): " INTPTR_FORMAT

                  "  _committed[%d].last(): " INTPTR_FORMAT,

                  ind, p2i(_committed[ind].start()),

                  ind, p2i(_committed[ind].last()));

    gclog_or_tty->print_cr("  "

                  "  byte_for(start): " INTPTR_FORMAT

                  "  byte_for(last): " INTPTR_FORMAT,

                  p2i(byte_for(_covered[ind].start())),

                  p2i(byte_for(_covered[ind].last())));

    gclog_or_tty->print_cr("  "

                  "  addr_for(start): " INTPTR_FORMAT

                  "  addr_for(last): " INTPTR_FORMAT,

                  p2i(addr_for((jbyte*) _committed[ind].start())),

                  p2i(addr_for((jbyte*) _committed[ind].last())));

  }

  // Touch the last card of the covered region to show that it

  // is committed (or SEGV).

  debug_only((void) (*byte_for(_covered[ind].last()));)

  debug_only(verify_guard();)

}

// Note that these versions are precise!  The scanning code has to handle the

// fact that the write barrier may be either precise or imprecise.

void CardTableModRefBS::write_ref_field_work(void* field, oop newVal, bool release) {

  inline_write_ref_field(field, newVal, release);

}

void CardTableModRefBS::non_clean_card_iterate_possibly_parallel(Space* sp,

                                                                 MemRegion mr,

                                                                 OopsInGenClosure* cl,

                                                                 CardTableRS* ct) {

  if (!mr.is_empty()) {

    // Caller (process_roots()) claims that all GC threads

    // execute this call.  With UseDynamicNumberOfGCThreads now all

    // active GC threads execute this call.  The number of active GC

    // threads needs to be passed to par_non_clean_card_iterate_work()

    // to get proper partitioning and termination.

    //

    // This is an example of where n_par_threads() is used instead

    // of workers()->active_workers().  n_par_threads can be set to 0 to

    // turn off parallelism.  For example when this code is called as

    // part of verification and SharedHeap::process_roots() is being

    // used, then n_par_threads() may have been set to 0.  active_workers

    // is not overloaded with the meaning that it is a switch to disable

    // parallelism and so keeps the meaning of the number of

    // active gc workers.  If parallelism has not been shut off by

    // setting n_par_threads to 0, then n_par_threads should be

    // equal to active_workers.  When a different mechanism for shutting

    // off parallelism is used, then active_workers can be used in

    // place of n_par_threads.

    //  This is an example of a path where n_par_threads is

    // set to 0 to turn off parallelism.

    //  [7] CardTableModRefBS::non_clean_card_iterate()

    //  [8] CardTableRS::younger_refs_in_space_iterate()

    //  [9] Generation::younger_refs_in_space_iterate()

    //  [10] OneContigSpaceCardGeneration::younger_refs_iterate()

    //  [11] CompactingPermGenGen::younger_refs_iterate()

    //  [12] CardTableRS::younger_refs_iterate()

    //  [13] SharedHeap::process_strong_roots()

    //  [14] G1CollectedHeap::verify()

    //  [15] Universe::verify()

    //  [16] G1CollectedHeap::do_collection_pause_at_safepoint()

    //

    int n_threads =  SharedHeap::heap()->n_par_threads();

    bool is_par = n_threads > 0;

    if (is_par) {

#if INCLUDE_ALL_GCS

      assert(SharedHeap::heap()->n_par_threads() ==

             SharedHeap::heap()->workers()->active_workers(), "Mismatch");

      non_clean_card_iterate_parallel_work(sp, mr, cl, ct, n_threads);

#else  // INCLUDE_ALL_GCS

      fatal("Parallel gc not supported here.");

#endif // INCLUDE_ALL_GCS

    } else {

      // We do not call the non_clean_card_iterate_serial() version below because

      // we want to clear the cards (which non_clean_card_iterate_serial() does not

      // do for us): clear_cl here does the work of finding contiguous dirty ranges

      // of cards to process and clear.

      DirtyCardToOopClosure* dcto_cl = sp->new_dcto_cl(cl, precision(),

                                                       cl->gen_boundary());

      ClearNoncleanCardWrapper clear_cl(dcto_cl, ct);

      clear_cl.do_MemRegion(mr);

    }

  }

}