/*

 * Copyright (c) 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/shared/c2/barrierSetC2.hpp"

#include "opto/arraycopynode.hpp"

#include "opto/graphKit.hpp"

#include "opto/idealKit.hpp"

#include "opto/narrowptrnode.hpp"

#include "utilities/macros.hpp"

// By default this is a no-op.

void BarrierSetC2::resolve_address(C2Access& access) const { }

void* C2Access::barrier_set_state() const {

  return _kit->barrier_set_state();

}

bool C2Access::needs_cpu_membar() const {

  bool mismatched = (_decorators & C2_MISMATCHED) != 0;

  bool is_unordered = (_decorators & MO_UNORDERED) != 0;

  bool anonymous = (_decorators & C2_UNSAFE_ACCESS) != 0;

  bool is_write = (_decorators & C2_WRITE_ACCESS) != 0;

  bool is_read = (_decorators & C2_READ_ACCESS) != 0;

  bool is_atomic = is_read && is_write;

  if (is_atomic) {

    // Atomics always need to be wrapped in CPU membars

    return true;

  }

  if (anonymous) {

    // We will need memory barriers unless we can determine a unique

    // alias category for this reference.  (Note:  If for some reason

    // the barriers get omitted and the unsafe reference begins to "pollute"

    // the alias analysis of the rest of the graph, either Compile::can_alias

    // or Compile::must_alias will throw a diagnostic assert.)

      return true;

    }

  }

  return false;

}

Node* BarrierSetC2::store_at_resolved(C2Access& access, C2AccessValue& val) const {

  DecoratorSet decorators = access.decorators();

  GraphKit* kit = access.kit();

  bool mismatched = (decorators & C2_MISMATCHED) != 0;

  bool unaligned = (decorators & C2_UNALIGNED) != 0;

  bool requires_atomic_access = (decorators & MO_UNORDERED) == 0;

  if (access.type() == T_DOUBLE) {

    Node* new_val = kit->dstore_rounding(val.node());

    val.set_node(new_val);

  }

  MemNode::MemOrd mo = access.mem_node_mo();

  Node* store = kit->store_to_memory(kit->control(), access.addr().node(), val.node(), access.type(),

                                     access.addr().type(), mo, requires_atomic_access, unaligned, mismatched);

  access.set_raw_access(store);

  return store;

}

Node* BarrierSetC2::load_at_resolved(C2Access& access, const Type* val_type) const {

  DecoratorSet decorators = access.decorators();

  GraphKit* kit = access.kit();

  Node* adr = access.addr().node();

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

  bool mismatched = (decorators & C2_MISMATCHED) != 0;

  bool requires_atomic_access = (decorators & MO_UNORDERED) == 0;

  bool unaligned = (decorators & C2_UNALIGNED) != 0;

  bool control_dependent = (decorators & C2_CONTROL_DEPENDENT_LOAD) != 0;

  bool pinned = (decorators & C2_PINNED_LOAD) != 0;

  MemNode::MemOrd mo = access.mem_node_mo();

  LoadNode::ControlDependency dep = pinned ? LoadNode::Pinned : LoadNode::DependsOnlyOnTest;

  Node* control = control_dependent ? kit->control() : NULL;

  Node* load = kit->make_load(control, adr, val_type, access.type(), adr_type, mo,

                              dep, requires_atomic_access, unaligned, mismatched);

  access.set_raw_access(load);

  return load;

}

class C2AccessFence: public StackObj {

  C2Access& _access;

public:

  C2AccessFence(C2Access& access) :

    _access(access) {

    GraphKit* kit = access.kit();

    DecoratorSet decorators = access.decorators();

    bool is_write = (decorators & C2_WRITE_ACCESS) != 0;

    bool is_read = (decorators & C2_READ_ACCESS) != 0;

    bool is_atomic = is_read && is_write;

    bool is_volatile = (decorators & MO_SEQ_CST) != 0;

    bool is_release = (decorators & MO_RELEASE) != 0;

    if (is_atomic) {

      // Memory-model-wise, a LoadStore acts like a little synchronized

      // block, so needs barriers on each side.  These don't translate

      // into actual barriers on most machines, but we still need rest of

      // compiler to respect ordering.

      if (is_release) {

        kit->insert_mem_bar(Op_MemBarRelease);

      } else if (is_volatile) {

        if (support_IRIW_for_not_multiple_copy_atomic_cpu) {

          kit->insert_mem_bar(Op_MemBarVolatile);

        } else {

          kit->insert_mem_bar(Op_MemBarRelease);

        }

      }

    } else if (is_write) {

      // If reference is volatile, prevent following memory ops from

      // floating down past the volatile write.  Also prevents commoning

      // another volatile read.

      if (is_volatile || is_release) {

        kit->insert_mem_bar(Op_MemBarRelease);

      }

    } else {

      // Memory barrier to prevent normal and 'unsafe' accesses from

      // bypassing each other.  Happens after null checks, so the

      // exception paths do not take memory state from the memory barrier,

      // so there's no problems making a strong assert about mixing users

      // of safe & unsafe memory.

      if (is_volatile && support_IRIW_for_not_multiple_copy_atomic_cpu) {

        kit->insert_mem_bar(Op_MemBarVolatile);

      }

    }

    if (access.needs_cpu_membar()) {

      kit->insert_mem_bar(Op_MemBarCPUOrder);

    }

    if (is_atomic) {

      // 4984716: MemBars must be inserted before this

      //          memory node in order to avoid a false

      //          dependency which will confuse the scheduler.

      access.set_memory();

    }

  }

  ~C2AccessFence() {

    GraphKit* kit = _access.kit();

    DecoratorSet decorators = _access.decorators();

    bool is_write = (decorators & C2_WRITE_ACCESS) != 0;

    bool is_read = (decorators & C2_READ_ACCESS) != 0;

    bool is_atomic = is_read && is_write;

    bool is_volatile = (decorators & MO_SEQ_CST) != 0;

    bool is_acquire = (decorators & MO_ACQUIRE) != 0;

    // If reference is volatile, prevent following volatiles ops from

    // floating up before the volatile access.

    if (_access.needs_cpu_membar()) {

      kit->insert_mem_bar(Op_MemBarCPUOrder);

    }

    if (is_atomic) {

      if (is_acquire || is_volatile) {

        kit->insert_mem_bar(Op_MemBarAcquire);

      }

    } else if (is_write) {

      // If not multiple copy atomic, we do the MemBarVolatile before the load.

      if (is_volatile && !support_IRIW_for_not_multiple_copy_atomic_cpu) {

        kit->insert_mem_bar(Op_MemBarVolatile); // Use fat membar

      }

    } else {

      if (is_volatile || is_acquire) {

        kit->insert_mem_bar(Op_MemBarAcquire, _access.raw_access());

      }

    }

  }

};

Node* BarrierSetC2::store_at(C2Access& access, C2AccessValue& val) const {

  C2AccessFence fence(access);

  resolve_address(access);

  return store_at_resolved(access, val);

}

Node* BarrierSetC2::load_at(C2Access& access, const Type* val_type) const {

  C2AccessFence fence(access);

  resolve_address(access);

  return load_at_resolved(access, val_type);

}

MemNode::MemOrd C2Access::mem_node_mo() const {

  bool is_write = (_decorators & C2_WRITE_ACCESS) != 0;

  bool is_read = (_decorators & C2_READ_ACCESS) != 0;

  if ((_decorators & MO_SEQ_CST) != 0) {

    if (is_write && is_read) {

      // For atomic operations

      return MemNode::seqcst;

    } else if (is_write) {

      return MemNode::release;

    } else {

      assert(is_read, "what else?");

      return MemNode::acquire;

    }

  } else if ((_decorators & MO_RELEASE) != 0) {

    return MemNode::release;

  } else if ((_decorators & MO_ACQUIRE) != 0) {

    return MemNode::acquire;

  } else if (is_write) {

    // Volatile fields need releasing stores.

    // Non-volatile fields also need releasing stores if they hold an

    // object reference, because the object reference might point to

    // a freshly created object.

    // Conservatively release stores of object references.

    return StoreNode::release_if_reference(_type);

  } else {

    return MemNode::unordered;

  }

}

void C2Access::fixup_decorators() {

  bool default_mo = (_decorators & MO_DECORATOR_MASK) == 0;

  bool is_unordered = (_decorators & MO_UNORDERED) != 0 || default_mo;

  bool anonymous = (_decorators & C2_UNSAFE_ACCESS) != 0;

  bool is_read = (_decorators & C2_READ_ACCESS) != 0;

  bool is_write = (_decorators & C2_WRITE_ACCESS) != 0;

  if (AlwaysAtomicAccesses && is_unordered) {

    _decorators &= ~MO_DECORATOR_MASK; // clear the MO bits

    _decorators |= MO_RELAXED; // Force the MO_RELAXED decorator with AlwaysAtomicAccess

  }

  _decorators = AccessInternal::decorator_fixup(_decorators);

  if (is_read && !is_write && anonymous) {

    // To be valid, unsafe loads may depend on other conditions than

    // the one that guards them: pin the Load node

    _decorators |= C2_CONTROL_DEPENDENT_LOAD;

    _decorators |= C2_PINNED_LOAD;

    const TypePtr* adr_type = _addr.type();

    Node* adr = _addr.node();

    if (!needs_cpu_membar() && adr_type->isa_instptr()) {

      assert(adr_type->meet(TypePtr::NULL_PTR) != adr_type->remove_speculative(), "should be not null");

      intptr_t offset = Type::OffsetBot;

      AddPNode::Ideal_base_and_offset(adr, &_kit->gvn(), offset);

      if (offset >= 0) {

        int s = Klass::layout_helper_size_in_bytes(adr_type->isa_instptr()->klass()->layout_helper());

        if (offset < s) {

          // Guaranteed to be a valid access, no need to pin it

          _decorators ^= C2_CONTROL_DEPENDENT_LOAD;

          _decorators ^= C2_PINNED_LOAD;

        }

      }

    }

  }

}

//--------------------------- atomic operations---------------------------------

static void pin_atomic_op(C2AtomicAccess& access) {

  if (!access.needs_pinning()) {

    return;

  }

  // SCMemProjNodes represent the memory state of a LoadStore. Their

  // main role is to prevent LoadStore nodes from being optimized away

  // when their results aren't used.

  GraphKit* kit = access.kit();

  Node* load_store = access.raw_access();

  assert(load_store != NULL, "must pin atomic op");

  Node* proj = kit->gvn().transform(new SCMemProjNode(load_store));

  kit->set_memory(proj, access.alias_idx());

}

void C2AtomicAccess::set_memory() {

  Node *mem = _kit->memory(_alias_idx);

  _memory = mem;

}

Node* BarrierSetC2::atomic_cmpxchg_val_at_resolved(C2AtomicAccess& access, Node* expected_val,

                                                   Node* new_val, const Type* value_type) const {

  GraphKit* kit = access.kit();

  MemNode::MemOrd mo = access.mem_node_mo();

  Node* mem = access.memory();

  Node* adr = access.addr().node();

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

  Node* load_store = NULL;

  if (access.is_oop()) {

#ifdef _LP64

    if (adr->bottom_type()->is_ptr_to_narrowoop()) {

      Node *newval_enc = kit->gvn().transform(new EncodePNode(new_val, new_val->bottom_type()->make_narrowoop()));

      Node *oldval_enc = kit->gvn().transform(new EncodePNode(expected_val, expected_val->bottom_type()->make_narrowoop()));

      load_store = kit->gvn().transform(new CompareAndExchangeNNode(kit->control(), mem, adr, newval_enc, oldval_enc, adr_type, value_type->make_narrowoop(), mo));

    } else

#endif

    {

      load_store = kit->gvn().transform(new CompareAndExchangePNode(kit->control(), mem, adr, new_val, expected_val, adr_type, value_type->is_oopptr(), mo));

    }

  } else {

    switch (access.type()) {

      case T_BYTE: {

        load_store = kit->gvn().transform(new CompareAndExchangeBNode(kit->control(), mem, adr, new_val, expected_val, adr_type, mo));

        break;

      }

      case T_SHORT: {

        load_store = kit->gvn().transform(new CompareAndExchangeSNode(kit->control(), mem, adr, new_val, expected_val, adr_type, mo));

        break;

      }

      case T_INT: {

        load_store = kit->gvn().transform(new CompareAndExchangeINode(kit->control(), mem, adr, new_val, expected_val, adr_type, mo));

        break;

      }

      case T_LONG: {

        load_store = kit->gvn().transform(new CompareAndExchangeLNode(kit->control(), mem, adr, new_val, expected_val, adr_type, mo));

        break;

      }

      default:

        ShouldNotReachHere();

    }

  }

  access.set_raw_access(load_store);

  pin_atomic_op(access);

#ifdef _LP64

  if (access.is_oop() && adr->bottom_type()->is_ptr_to_narrowoop()) {

    return kit->gvn().transform(new DecodeNNode(load_store, load_store->get_ptr_type()));

  }

#endif

  return load_store;

}

Node* BarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicAccess& access, Node* expected_val,

                                                    Node* new_val, const Type* value_type) const {

  GraphKit* kit = access.kit();

  DecoratorSet decorators = access.decorators();

  MemNode::MemOrd mo = access.mem_node_mo();

  Node* mem = access.memory();

  bool is_weak_cas = (decorators & C2_WEAK_CMPXCHG) != 0;

  Node* load_store = NULL;

  Node* adr = access.addr().node();

  if (access.is_oop()) {

#ifdef _LP64

    if (adr->bottom_type()->is_ptr_to_narrowoop()) {

      Node *newval_enc = kit->gvn().transform(new EncodePNode(new_val, new_val->bottom_type()->make_narrowoop()));

      Node *oldval_enc = kit->gvn().transform(new EncodePNode(expected_val, expected_val->bottom_type()->make_narrowoop()));

      if (is_weak_cas) {

        load_store = kit->gvn().transform(new WeakCompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));

      } else {

        load_store = kit->gvn().transform(new CompareAndSwapNNode(kit->control(), mem, adr, newval_enc, oldval_enc, mo));

      }

    } else

#endif

    {

      if (is_weak_cas) {

        load_store = kit->gvn().transform(new WeakCompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));

      } else {

        load_store = kit->gvn().transform(new CompareAndSwapPNode(kit->control(), mem, adr, new_val, expected_val, mo));

      }

    }

  } else {

    switch(access.type()) {

      case T_BYTE: {

        if (is_weak_cas) {

          load_store = kit->gvn().transform(new WeakCompareAndSwapBNode(kit->control(), mem, adr, new_val, expected_val, mo));

        } else {

          load_store = kit->gvn().transform(new CompareAndSwapBNode(kit->control(), mem, adr, new_val, expected_val, mo));

        }

        break;

      }

      case T_SHORT: {

        if (is_weak_cas) {

          load_store = kit->gvn().transform(new WeakCompareAndSwapSNode(kit->control(), mem, adr, new_val, expected_val, mo));

        } else {

          load_store = kit->gvn().transform(new CompareAndSwapSNode(kit->control(), mem, adr, new_val, expected_val, mo));

        }

        break;

      }

      case T_INT: {

        if (is_weak_cas) {

          load_store = kit->gvn().transform(new WeakCompareAndSwapINode(kit->control(), mem, adr, new_val, expected_val, mo));

        } else {

          load_store = kit->gvn().transform(new CompareAndSwapINode(kit->control(), mem, adr, new_val, expected_val, mo));

        }

        break;

      }

      case T_LONG: {

        if (is_weak_cas) {

          load_store = kit->gvn().transform(new WeakCompareAndSwapLNode(kit->control(), mem, adr, new_val, expected_val, mo));

        } else {

          load_store = kit->gvn().transform(new CompareAndSwapLNode(kit->control(), mem, adr, new_val, expected_val, mo));

        }

        break;

      }

      default:

        ShouldNotReachHere();

    }

  }

  access.set_raw_access(load_store);

  pin_atomic_op(access);

  return load_store;

}

Node* BarrierSetC2::atomic_xchg_at_resolved(C2AtomicAccess& access, Node* new_val, const Type* value_type) const {

  GraphKit* kit = access.kit();

  Node* mem = access.memory();

  Node* adr = access.addr().node();

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

  Node* load_store = NULL;

  if (access.is_oop()) {

#ifdef _LP64

    if (adr->bottom_type()->is_ptr_to_narrowoop()) {

      Node *newval_enc = kit->gvn().transform(new EncodePNode(new_val, new_val->bottom_type()->make_narrowoop()));

      load_store = kit->gvn().transform(new GetAndSetNNode(kit->control(), mem, adr, newval_enc, adr_type, value_type->make_narrowoop()));

    } else

#endif

    {

      load_store = kit->gvn().transform(new GetAndSetPNode(kit->control(), mem, adr, new_val, adr_type, value_type->is_oopptr()));

    }

  } else  {

    switch (access.type()) {

      case T_BYTE:

        load_store = kit->gvn().transform(new GetAndSetBNode(kit->control(), mem, adr, new_val, adr_type));

        break;

      case T_SHORT:

        load_store = kit->gvn().transform(new GetAndSetSNode(kit->control(), mem, adr, new_val, adr_type));

        break;

      case T_INT:

        load_store = kit->gvn().transform(new GetAndSetINode(kit->control(), mem, adr, new_val, adr_type));

        break;

      case T_LONG:

        load_store = kit->gvn().transform(new GetAndSetLNode(kit->control(), mem, adr, new_val, adr_type));

        break;

      default:

        ShouldNotReachHere();

    }

  }

  access.set_raw_access(load_store);

  pin_atomic_op(access);

#ifdef _LP64

  if (access.is_oop() && adr->bottom_type()->is_ptr_to_narrowoop()) {

    return kit->gvn().transform(new DecodeNNode(load_store, load_store->get_ptr_type()));

  }

#endif

  return load_store;

}

Node* BarrierSetC2::atomic_add_at_resolved(C2AtomicAccess& access, Node* new_val, const Type* value_type) const {

  Node* load_store = NULL;

  GraphKit* kit = access.kit();

  Node* adr = access.addr().node();

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

  Node* mem = access.memory();

  switch(access.type()) {

    case T_BYTE:

      load_store = kit->gvn().transform(new GetAndAddBNode(kit->control(), mem, adr, new_val, adr_type));

      break;

    case T_SHORT:

      load_store = kit->gvn().transform(new GetAndAddSNode(kit->control(), mem, adr, new_val, adr_type));

      break;

    case T_INT:

      load_store = kit->gvn().transform(new GetAndAddINode(kit->control(), mem, adr, new_val, adr_type));

      break;

    case T_LONG:

      load_store = kit->gvn().transform(new GetAndAddLNode(kit->control(), mem, adr, new_val, adr_type));

      break;

    default:

      ShouldNotReachHere();

  }

  access.set_raw_access(load_store);

  pin_atomic_op(access);

  return load_store;

}

Node* BarrierSetC2::atomic_cmpxchg_val_at(C2AtomicAccess& access, Node* expected_val,

                                          Node* new_val, const Type* value_type) const {

  C2AccessFence fence(access);

  resolve_address(access);

  return atomic_cmpxchg_val_at_resolved(access, expected_val, new_val, value_type);