/*

 * 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 "ci/ciUtilities.hpp"

#include "gc/shared/cardTable.hpp"

#include "gc/shared/cardTableBarrierSet.hpp"

#include "gc/shared/c2/cardTableBarrierSetC2.hpp"

#include "opto/arraycopynode.hpp"

#include "opto/graphKit.hpp"

#include "opto/idealKit.hpp"

#include "opto/macro.hpp"

#include "utilities/macros.hpp"

#define __ ideal.

Node* CardTableBarrierSetC2::byte_map_base_node(GraphKit* kit) const {

  // Get base of card map

  CardTable::CardValue* card_table_base = ci_card_table_address();

   if (card_table_base != NULL) {

     return kit->makecon(TypeRawPtr::make((address)card_table_base));

   } else {

     return kit->null();

   }

}

// vanilla/CMS post barrier

// Insert a write-barrier store.  This is to let generational GC work; we have

// to flag all oop-stores before the next GC point.

void CardTableBarrierSetC2::post_barrier(GraphKit* kit,

                                         Node* ctl,

                                         Node* oop_store,

                                         Node* obj,

                                         Node* adr,

                                         uint  adr_idx,

                                         Node* val,

                                         BasicType bt,

                                         bool use_precise) const {

  CardTableBarrierSet* ctbs = barrier_set_cast<CardTableBarrierSet>(BarrierSet::barrier_set());

  CardTable* ct = ctbs->card_table();

  // No store check needed if we're storing a NULL or an old object

  // (latter case is probably a string constant). The concurrent

  // mark sweep garbage collector, however, needs to have all nonNull

  // oop updates flagged via card-marks.

  if (val != NULL && val->is_Con()) {

    // must be either an oop or NULL

    const Type* t = val->bottom_type();

    if (t == TypePtr::NULL_PTR || t == Type::TOP)

      // stores of null never (?) need barriers

      return;

  }

  if (use_ReduceInitialCardMarks()

      && obj == kit->just_allocated_object(kit->control())) {

    // We can skip marks on a freshly-allocated object in Eden.

    // Keep this code in sync with new_deferred_store_barrier() in runtime.cpp.

    // That routine informs GC to take appropriate compensating steps,

    // upon a slow-path allocation, so as to make this card-mark

    // elision safe.

    return;

  }

  if (!use_precise) {

    // All card marks for a (non-array) instance are in one place:

    adr = obj;

  }

  // (Else it's an array (or unknown), and we want more precise card marks.)

  assert(adr != NULL, "");

  IdealKit ideal(kit, true);

  // Convert the pointer to an int prior to doing math on it

  Node* cast = __ CastPX(__ ctrl(), adr);

  // Divide by card size

  Node* card_offset = __ URShiftX( cast, __ ConI(CardTable::card_shift) );

  // Combine card table base and card offset

  Node* card_adr = __ AddP(__ top(), byte_map_base_node(kit), card_offset );

  // Get the alias_index for raw card-mark memory

  int adr_type = Compile::AliasIdxRaw;

  Node*   zero = __ ConI(0); // Dirty card value

  if (UseCondCardMark) {

    if (ct->scanned_concurrently()) {

      kit->insert_mem_bar(Op_MemBarVolatile, oop_store);

      __ sync_kit(kit);

    }

    // The classic GC reference write barrier is typically implemented

    // as a store into the global card mark table.  Unfortunately

    // unconditional stores can result in false sharing and excessive

    // coherence traffic as well as false transactional aborts.

    // UseCondCardMark enables MP "polite" conditional card mark

    // stores.  In theory we could relax the load from ctrl() to

    // no_ctrl, but that doesn't buy much latitude.

    Node* card_val = __ load( __ ctrl(), card_adr, TypeInt::BYTE, T_BYTE, adr_type);

    __ if_then(card_val, BoolTest::ne, zero);

  }

  // Smash zero into card

  if(!ct->scanned_concurrently()) {

    __ store(__ ctrl(), card_adr, zero, T_BYTE, adr_type, MemNode::unordered);

  } else {

    // Specialized path for CM store barrier

    __ storeCM(__ ctrl(), card_adr, zero, oop_store, adr_idx, T_BYTE, adr_type);

  }

  if (UseCondCardMark) {

    __ end_if();

  }

  // Final sync IdealKit and GraphKit.

  kit->final_sync(ideal);

}

void CardTableBarrierSetC2::clone(GraphKit* kit, Node* src, Node* dst, Node* size, bool is_array) const {

  BarrierSetC2::clone(kit, src, dst, size, is_array);

  const TypePtr* raw_adr_type = TypeRawPtr::BOTTOM;

  // If necessary, emit some card marks afterwards.  (Non-arrays only.)

  bool card_mark = !is_array && !use_ReduceInitialCardMarks();

  if (card_mark) {

    assert(!is_array, "");

    // Put in store barrier for any and all oops we are sticking

    // into this object.  (We could avoid this if we could prove

    // that the object type contains no oop fields at all.)

    Node* no_particular_value = NULL;

    Node* no_particular_field = NULL;

    int raw_adr_idx = Compile::AliasIdxRaw;

    post_barrier(kit, kit->control(),

                 kit->memory(raw_adr_type),

                 dst,

                 no_particular_field,

                 raw_adr_idx,

                 no_particular_value,

                 T_OBJECT,

                 false);

  }

}

bool CardTableBarrierSetC2::use_ReduceInitialCardMarks() const {

  return ReduceInitialCardMarks;

}

bool CardTableBarrierSetC2::is_gc_barrier_node(Node* node) const {

  return ModRefBarrierSetC2::is_gc_barrier_node(node) || node->Opcode() == Op_StoreCM;

}

void CardTableBarrierSetC2::eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const {

  assert(node->Opcode() == Op_CastP2X, "ConvP2XNode required");

  Node *shift = node->unique_out();

  Node *addp = shift->unique_out();

  for (DUIterator_Last jmin, j = addp->last_outs(jmin); j >= jmin; --j) {

    Node *mem = addp->last_out(j);

    if (UseCondCardMark && mem->is_Load()) {

      assert(mem->Opcode() == Op_LoadB, "unexpected code shape");

      // The load is checking if the card has been written so

      // replace it with zero to fold the test.

      macro->replace_node(mem, macro->intcon(0));

      continue;

    }

    assert(mem->is_Store(), "store required");

    macro->replace_node(mem, mem->in(MemNode::Memory));

  }

}

bool CardTableBarrierSetC2::array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type, bool is_clone, ArrayCopyPhase phase) const {

  return is_oop && (!tightly_coupled_alloc || !use_ReduceInitialCardMarks());

}