/*

 * Copyright (c) 2013, 2019, Red Hat, Inc. All rights reserved.

 *

 * 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/shenandoah/shenandoahAsserts.hpp"

#include "gc/shenandoah/shenandoahBarrierSet.hpp"

#include "gc/shenandoah/shenandoahBarrierSetClone.inline.hpp"

#include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"

#include "gc/shenandoah/shenandoahCollectorPolicy.hpp"

#include "gc/shenandoah/shenandoahConcurrentRoots.hpp"

#include "gc/shenandoah/shenandoahHeap.inline.hpp"

#include "gc/shenandoah/shenandoahHeuristics.hpp"

#include "gc/shenandoah/shenandoahTraversalGC.hpp"

#include "memory/iterator.inline.hpp"

#include "runtime/interfaceSupport.inline.hpp"

#ifdef COMPILER1

#include "gc/shenandoah/c1/shenandoahBarrierSetC1.hpp"

#endif

#ifdef COMPILER2

#include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"

#endif

class ShenandoahBarrierSetC1;

class ShenandoahBarrierSetC2;

ShenandoahBarrierSet::ShenandoahBarrierSet(ShenandoahHeap* heap) :

  BarrierSet(make_barrier_set_assembler<ShenandoahBarrierSetAssembler>(),

             make_barrier_set_c1<ShenandoahBarrierSetC1>(),

             make_barrier_set_c2<ShenandoahBarrierSetC2>(),

             NULL /* barrier_set_nmethod */,

             BarrierSet::FakeRtti(BarrierSet::ShenandoahBarrierSet)),

  _heap(heap),

  _satb_mark_queue_buffer_allocator("SATB Buffer Allocator", ShenandoahSATBBufferSize),

  _satb_mark_queue_set(&_satb_mark_queue_buffer_allocator)

{

}

ShenandoahBarrierSetAssembler* ShenandoahBarrierSet::assembler() {

  BarrierSetAssembler* const bsa = BarrierSet::barrier_set()->barrier_set_assembler();

  return reinterpret_cast<ShenandoahBarrierSetAssembler*>(bsa);

}

void ShenandoahBarrierSet::print_on(outputStream* st) const {

  st->print("ShenandoahBarrierSet");

}

bool ShenandoahBarrierSet::is_a(BarrierSet::Name bsn) {

  return bsn == BarrierSet::ShenandoahBarrierSet;

}

bool ShenandoahBarrierSet::is_aligned(HeapWord* hw) {

  return true;

}

bool ShenandoahBarrierSet::need_load_reference_barrier(DecoratorSet decorators, BasicType type) {

  if (!ShenandoahLoadRefBarrier) return false;

  // Only needed for references

  return is_reference_type(type);

}

bool ShenandoahBarrierSet::use_load_reference_barrier_native(DecoratorSet decorators, BasicType type) {

  assert(need_load_reference_barrier(decorators, type), "Should be subset of LRB");

  assert(is_reference_type(type), "Why we here?");

  // Native load reference barrier is only needed for concurrent root processing

  if (!ShenandoahConcurrentRoots::can_do_concurrent_roots()) {

    return false;

  }

  return (decorators & IN_NATIVE) != 0;

}

bool ShenandoahBarrierSet::need_keep_alive_barrier(DecoratorSet decorators,BasicType type) {

  if (!ShenandoahKeepAliveBarrier) return false;

  // Only needed for references

  if (!is_reference_type(type)) return false;

  bool keep_alive = (decorators & AS_NO_KEEPALIVE) == 0;

  bool unknown = (decorators & ON_UNKNOWN_OOP_REF) != 0;

  bool is_traversal_mode = ShenandoahHeap::heap()->is_traversal_mode();

  bool on_weak_ref = (decorators & (ON_WEAK_OOP_REF | ON_PHANTOM_OOP_REF)) != 0;

  return (on_weak_ref || unknown) && (keep_alive || is_traversal_mode);

}

oop ShenandoahBarrierSet::load_reference_barrier_not_null(oop obj) {

  if (ShenandoahLoadRefBarrier && _heap->has_forwarded_objects()) {

    return load_reference_barrier_impl(obj);

  } else {

    return obj;

  }

}

oop ShenandoahBarrierSet::load_reference_barrier(oop obj) {

  if (obj != NULL) {

    return load_reference_barrier_not_null(obj);

  } else {

    return obj;

  }

}

oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, oop* load_addr) {

  return load_reference_barrier_mutator_work(obj, load_addr);

}

oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, narrowOop* load_addr) {

  return load_reference_barrier_mutator_work(obj, load_addr);

}

template <class T>

oop ShenandoahBarrierSet::load_reference_barrier_mutator_work(oop obj, T* load_addr) {

  assert(ShenandoahLoadRefBarrier, "should be enabled");

  shenandoah_assert_in_cset(load_addr, obj);

  oop fwd = resolve_forwarded_not_null(obj);

  if (obj == fwd) {

    assert(_heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL),

           "evac should be in progress");

    ShenandoahEvacOOMScope oom_evac_scope;

    Thread* thread = Thread::current();

    oop res_oop = _heap->evacuate_object(obj, thread);

    // Since we are already here and paid the price of getting through runtime call adapters

    // and acquiring oom-scope, it makes sense to try and evacuate more adjacent objects,

    // thus amortizing the overhead. For sparsely live heaps, scan costs easily dominate

    // total assist costs, and can introduce a lot of evacuation latency. This is why we

    // only scan for _nearest_ N objects, regardless if they are eligible for evac or not.

    // The scan itself should also avoid touching the non-marked objects below TAMS, because

    // their metadata (notably, klasses) may be incorrect already.

    size_t max = ShenandoahEvacAssist;

    if (max > 0) {

      // Traversal is special: it uses incomplete marking context, because it coalesces evac with mark.

      // Other code uses complete marking context, because evac happens after the mark.

      ShenandoahMarkingContext* ctx = _heap->is_concurrent_traversal_in_progress() ?

                                      _heap->marking_context() : _heap->complete_marking_context();

      ShenandoahHeapRegion* r = _heap->heap_region_containing(obj);

      assert(r->is_cset(), "sanity");

      HeapWord* cur = (HeapWord*)obj + obj->size();

      size_t count = 0;

      while ((cur < r->top()) && ctx->is_marked(oop(cur)) && (count++ < max)) {

        oop cur_oop = oop(cur);

        if (cur_oop == resolve_forwarded_not_null(cur_oop)) {

          _heap->evacuate_object(cur_oop, thread);

        }

        cur = cur + cur_oop->size();

      }

    }

    fwd = res_oop;

  }

  if (load_addr != NULL && fwd != obj) {

    // Since we are here and we know the load address, update the reference.

    ShenandoahHeap::cas_oop(fwd, load_addr, obj);

  }

  return fwd;

}

oop ShenandoahBarrierSet::load_reference_barrier_impl(oop obj) {

  assert(ShenandoahLoadRefBarrier, "should be enabled");

  if (!CompressedOops::is_null(obj)) {

    bool evac_in_progress = _heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL);

    oop fwd = resolve_forwarded_not_null(obj);

    if (evac_in_progress &&

        _heap->in_collection_set(obj) &&

        obj == fwd) {

      Thread *t = Thread::current();

      if (t->is_GC_task_thread()) {

        return _heap->evacuate_object(obj, t);

      } else {

        ShenandoahEvacOOMScope oom_evac_scope;

        return _heap->evacuate_object(obj, t);

      }

    } else {

      return fwd;

    }

  } else {

    return obj;

  }

}

void ShenandoahBarrierSet::on_thread_create(Thread* thread) {

  // Create thread local data

  ShenandoahThreadLocalData::create(thread);

}

void ShenandoahBarrierSet::on_thread_destroy(Thread* thread) {

  // Destroy thread local data

  ShenandoahThreadLocalData::destroy(thread);

}

void ShenandoahBarrierSet::on_thread_attach(Thread *thread) {

  assert(!thread->is_Java_thread() || !SafepointSynchronize::is_at_safepoint(),

         "We should not be at a safepoint");

  SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);

  assert(!queue.is_active(), "SATB queue should not be active");

  assert( queue.is_empty(),  "SATB queue should be empty");

  queue.set_active(_satb_mark_queue_set.is_active());

  if (thread->is_Java_thread()) {

    ShenandoahThreadLocalData::set_gc_state(thread, _heap->gc_state());

    ShenandoahThreadLocalData::initialize_gclab(thread);

  }

}

void ShenandoahBarrierSet::on_thread_detach(Thread *thread) {

  SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);

  queue.flush();

  if (thread->is_Java_thread()) {

    PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);

    if (gclab != NULL) {

      gclab->retire();

    }

  }

}

oop ShenandoahBarrierSet::load_reference_barrier_native(oop obj, oop* load_addr) {

  return load_reference_barrier_native_impl(obj, load_addr);

}

oop ShenandoahBarrierSet::load_reference_barrier_native(oop obj, narrowOop* load_addr) {

  // Assumption: narrow oop version should not be used anywhere.

  ShouldNotReachHere();

  return NULL;

}

template <class T>

oop ShenandoahBarrierSet::load_reference_barrier_native_impl(oop obj, T* load_addr) {

  if (CompressedOops::is_null(obj)) {

    return NULL;

  }

  ShenandoahMarkingContext* const marking_context = _heap->marking_context();

  if (_heap->is_evacuation_in_progress() && !marking_context->is_marked(obj)) {

    Thread* thr = Thread::current();

    if (thr->is_Java_thread()) {

      return NULL;

    } else {

      return obj;

    }

  }

  oop fwd = load_reference_barrier_not_null(obj);

  if (load_addr != NULL && fwd != obj) {

    // Since we are here and we know the load address, update the reference.

    ShenandoahHeap::cas_oop(fwd, load_addr, obj);

  }

  return fwd;

}

void ShenandoahBarrierSet::clone_barrier_runtime(oop src) {

  if (_heap->has_forwarded_objects()) {

    clone_barrier(src);

  }

}