/*

 * Copyright (c) 2002, 2018, 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 "gc/parallel/mutableSpace.hpp"

#include "gc/parallel/parallelScavengeHeap.hpp"

#include "gc/parallel/psPromotionLAB.hpp"

#include "memory/universe.hpp"

#include "oops/oop.inline.hpp"

size_t PSPromotionLAB::filler_header_size;

// This is the shared initialization code. It sets up the basic pointers,

// and allows enough extra space for a filler object. We call a virtual

// method, "lab_is_valid()" to handle the different asserts the old/young

// labs require.

void PSPromotionLAB::initialize(MemRegion lab) {

  assert(lab_is_valid(lab), "Sanity");

  HeapWord* bottom = lab.start();

  HeapWord* end    = lab.end();

  set_bottom(bottom);

  set_end(end);

  set_top(bottom);

  // Initialize after VM starts up because header_size depends on compressed

  // oops.

  filler_header_size = align_object_size(typeArrayOopDesc::header_size(T_INT));

  // We can be initialized to a zero size!

  if (free() > 0) {

    if (ZapUnusedHeapArea) {

      debug_only(Copy::fill_to_words(top(), free()/HeapWordSize, badHeapWord));

    }

    // NOTE! We need to allow space for a filler object.

    assert(lab.word_size() >= filler_header_size, "lab is too small");

    end = end - filler_header_size;

    set_end(end);

    _state = needs_flush;

  } else {

    _state = zero_size;

  }

  assert(this->top() <= this->end(), "pointers out of order");

}

// Fill all remaining lab space with an unreachable object.

// The goal is to leave a contiguous parseable span of objects.

void PSPromotionLAB::flush() {

  assert(_state != flushed, "Attempt to flush PLAB twice");

  assert(top() <= end(), "pointers out of order");

  // If we were initialized to a zero sized lab, there is

  // nothing to flush

  if (_state == zero_size)

    return;

  // PLAB's never allocate the last aligned_header_size

  // so they can always fill with an array.

  HeapWord* tlab_end = end() + filler_header_size;

  typeArrayOop filler_oop = (typeArrayOop) top();

  filler_oop->set_klass(Universe::intArrayKlassObj());

  const size_t array_length =

    pointer_delta(tlab_end, top()) - typeArrayOopDesc::header_size(T_INT);

  assert( (array_length * (HeapWordSize/sizeof(jint))) < (size_t)max_jint, "array too big in PSPromotionLAB");

  filler_oop->set_length((int)(array_length * (HeapWordSize/sizeof(jint))));

#ifdef ASSERT

  // Note that we actually DO NOT want to use the aligned header size!

  HeapWord* elt_words = ((HeapWord*)filler_oop) + typeArrayOopDesc::header_size(T_INT);

  Copy::fill_to_words(elt_words, array_length, 0xDEAABABE);

#endif

  set_bottom(NULL);

  set_end(NULL);

  set_top(NULL);

  _state = flushed;

}

bool PSPromotionLAB::unallocate_object(HeapWord* obj, size_t obj_size) {

  assert(ParallelScavengeHeap::heap()->is_in(obj), "Object outside heap");

  if (contains(obj)) {

    HeapWord* object_end = obj + obj_size;

    assert(object_end == top(), "Not matching last allocation");

    set_top(obj);

    return true;

  }

  return false;

}

// Fill all remaining lab space with an unreachable object.

// The goal is to leave a contiguous parseable span of objects.

void PSOldPromotionLAB::flush() {

  assert(_state != flushed, "Attempt to flush PLAB twice");

  assert(top() <= end(), "pointers out of order");

  if (_state == zero_size)

    return;

  HeapWord* obj = top();

  PSPromotionLAB::flush();

  assert(_start_array != NULL, "Sanity");

  _start_array->allocate_block(obj);

}

#ifdef ASSERT

bool PSYoungPromotionLAB::lab_is_valid(MemRegion lab) {

  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();

  MutableSpace* to_space = heap->young_gen()->to_space();

  MemRegion used = to_space->used_region();

  if (used.contains(lab)) {

    return true;

  }

  return false;

}

bool PSOldPromotionLAB::lab_is_valid(MemRegion lab) {

  assert(_start_array->covered_region().contains(lab), "Sanity");

  ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();

  PSOldGen* old_gen = heap->old_gen();

  MemRegion used = old_gen->object_space()->used_region();

  if (used.contains(lab)) {

    return true;

  }

  return false;

}

#endif /* ASSERT */