src/hotspot/share/gc/shared/c2/modRefBarrierSetC2.cpp

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 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
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 * 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.
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#include "precompiled.hpp"
#include "opto/arraycopynode.hpp"
#include "opto/graphKit.hpp"
#include "opto/idealKit.hpp"
#include "opto/narrowptrnode.hpp"
#include "gc/shared/c2/modRefBarrierSetC2.hpp"
#include "utilities/macros.hpp"

Node* ModRefBarrierSetC2::store_at_resolved(C2Access& access, C2AccessValue& val) const {
  DecoratorSet decorators = access.decorators();
  GraphKit* kit = access.kit();

  const TypePtr* adr_type = access.addr().type();
  Node* adr = access.addr().node();

  bool is_array = (decorators & IS_ARRAY) != 0;
  bool anonymous = (decorators & ON_UNKNOWN_OOP_REF) != 0;
  bool in_heap = (decorators & IN_HEAP) != 0;
  bool use_precise = is_array || anonymous;

  if (!access.is_oop() || (!in_heap && !anonymous)) {
    return BarrierSetC2::store_at_resolved(access, val);
  }

  uint adr_idx = kit->C->get_alias_index(adr_type);
  assert(adr_idx != Compile::AliasIdxTop, "use other store_to_memory factory" );

  pre_barrier(kit, true /* do_load */, kit->control(), access.base(), adr, adr_idx, val.node(),
              static_cast<const TypeOopPtr*>(val.type()), NULL /* pre_val */, access.type());
  Node* store = BarrierSetC2::store_at_resolved(access, val);
  post_barrier(kit, kit->control(), access.raw_access(), access.base(), adr, adr_idx, val.node(),
               access.type(), use_precise);

  return store;
}

Node* ModRefBarrierSetC2::atomic_cmpxchg_val_at_resolved(C2AtomicAccess& access, Node* expected_val,
                                                         Node* new_val, const Type* value_type) const {
  GraphKit* kit = access.kit();

  if (!access.is_oop()) {
    return BarrierSetC2::atomic_cmpxchg_val_at_resolved(access, expected_val, new_val, value_type);
  }

  pre_barrier(kit, false /* do_load */,
              kit->control(), NULL, NULL, max_juint, NULL, NULL,
              expected_val /* pre_val */, T_OBJECT);

  Node* result = BarrierSetC2::atomic_cmpxchg_val_at_resolved(access, expected_val, new_val, value_type);

  post_barrier(kit, kit->control(), access.raw_access(), access.base(),
               access.addr().node(), access.alias_idx(), new_val, T_OBJECT, true);

  return result;
}

Node* ModRefBarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicAccess& access, Node* expected_val,
                                                          Node* new_val, const Type* value_type) const {
  GraphKit* kit = access.kit();

  if (!access.is_oop()) {
    return BarrierSetC2::atomic_cmpxchg_bool_at_resolved(access, expected_val, new_val, value_type);
  }

  pre_barrier(kit, false /* do_load */,
              kit->control(), NULL, NULL, max_juint, NULL, NULL,
              expected_val /* pre_val */, T_OBJECT);

  Node* load_store = BarrierSetC2::atomic_cmpxchg_bool_at_resolved(access, expected_val, new_val, value_type);

  // Emit the post barrier only when the actual store happened. This makes sense
  // to check only for LS_cmp_* that can fail to set the value.
  // LS_cmp_exchange does not produce any branches by default, so there is no
  // boolean result to piggyback on. TODO: When we merge CompareAndSwap with
  // CompareAndExchange and move branches here, it would make sense to conditionalize
  // post_barriers for LS_cmp_exchange as well.
  //
  // CAS success path is marked more likely since we anticipate this is a performance
  // critical path, while CAS failure path can use the penalty for going through unlikely
  // path as backoff. Which is still better than doing a store barrier there.
  IdealKit ideal(kit);
  ideal.if_then(load_store, BoolTest::ne, ideal.ConI(0), PROB_STATIC_FREQUENT); {
    kit->sync_kit(ideal);
    post_barrier(kit, ideal.ctrl(), access.raw_access(), access.base(),
                 access.addr().node(), access.alias_idx(), new_val, T_OBJECT, true);
    ideal.sync_kit(kit);
  } ideal.end_if();
  kit->final_sync(ideal);

  return load_store;
}

Node* ModRefBarrierSetC2::atomic_xchg_at_resolved(C2AtomicAccess& access, Node* new_val, const Type* value_type) const {
  GraphKit* kit = access.kit();

  Node* result = BarrierSetC2::atomic_xchg_at_resolved(access, new_val, value_type);
  if (!access.is_oop()) {
    return result;
  }

  // Don't need to load pre_val. The old value is returned by load_store.
  // The pre_barrier can execute after the xchg as long as no safepoint
  // gets inserted between them.
  pre_barrier(kit, false /* do_load */,
              kit->control(), NULL, NULL, max_juint, NULL, NULL,
              result /* pre_val */, T_OBJECT);
  post_barrier(kit, kit->control(), access.raw_access(), access.base(), access.addr().node(),
               access.alias_idx(), new_val, T_OBJECT, true);

  return result;
}