/*

 * Copyright (c) 2015, 2019, 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

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 */

#include "precompiled.hpp"

#include "classfile/javaClasses.hpp"

#include "gc/z/c2/zBarrierSetC2.hpp"

#include "gc/z/zBarrierSet.hpp"

#include "gc/z/zBarrierSetAssembler.hpp"

#include "gc/z/zBarrierSetRuntime.hpp"

#include "opto/block.hpp"

#include "opto/compile.hpp"

#include "opto/graphKit.hpp"

#include "opto/machnode.hpp"

#include "opto/memnode.hpp"

#include "opto/node.hpp"

#include "opto/regalloc.hpp"

#include "opto/rootnode.hpp"

#include "utilities/growableArray.hpp"

#include "utilities/macros.hpp"

class ZBarrierSetC2State : public ResourceObj {

private:

  GrowableArray<ZLoadBarrierStubC2*>* _stubs;

  Node_Array                          _live;

public:

  ZBarrierSetC2State(Arena* arena) :

    _stubs(new (arena) GrowableArray<ZLoadBarrierStubC2*>(arena, 8,  0, NULL)),

    _live(arena) {}

  GrowableArray<ZLoadBarrierStubC2*>* stubs() {

    return _stubs;

  }

  RegMask* live(const Node* node) {

    if (!node->is_Mach()) {

      // Don't need liveness for non-MachNodes

      return NULL;

    }

    const MachNode* const mach = node->as_Mach();

    if (mach->barrier_data() != ZLoadBarrierStrong &&

        mach->barrier_data() != ZLoadBarrierWeak) {

      // Don't need liveness data for nodes without barriers

      return NULL;

    }

    RegMask* live = (RegMask*)_live[node->_idx];

    if (live == NULL) {

      live = new (Compile::current()->comp_arena()->Amalloc_D(sizeof(RegMask))) RegMask();

      _live.map(node->_idx, (Node*)live);

    }

    return live;

  }

};

static ZBarrierSetC2State* barrier_set_state() {

  return reinterpret_cast<ZBarrierSetC2State*>(Compile::current()->barrier_set_state());

}

ZLoadBarrierStubC2* ZLoadBarrierStubC2::create(const MachNode* node, Address ref_addr, Register ref, Register tmp, bool weak) {

  ZLoadBarrierStubC2* const stub = new (Compile::current()->comp_arena()) ZLoadBarrierStubC2(node, ref_addr, ref, tmp, weak);

  if (!Compile::current()->in_scratch_emit_size()) {

    barrier_set_state()->stubs()->append(stub);

  }

  return stub;

}

ZLoadBarrierStubC2::ZLoadBarrierStubC2(const MachNode* node, Address ref_addr, Register ref, Register tmp, bool weak) :

    _node(node),

    _ref_addr(ref_addr),

    _ref(ref),

    _tmp(tmp),

    _weak(weak),

    _entry(),

    _continuation() {

  assert_different_registers(ref, ref_addr.base());

  assert_different_registers(ref, ref_addr.index());

}

Address ZLoadBarrierStubC2::ref_addr() const {

  return _ref_addr;

}

Register ZLoadBarrierStubC2::ref() const {

  return _ref;

}

Register ZLoadBarrierStubC2::tmp() const {

  return _tmp;

}

address ZLoadBarrierStubC2::slow_path() const {

  const DecoratorSet decorators = _weak ? ON_WEAK_OOP_REF : ON_STRONG_OOP_REF;

  return ZBarrierSetRuntime::load_barrier_on_oop_field_preloaded_addr(decorators);

}

RegMask& ZLoadBarrierStubC2::live() const {

  return *barrier_set_state()->live(_node);

}

Label* ZLoadBarrierStubC2::entry() {

  // The _entry will never be bound when in_scratch_emit_size() is true.

  // However, we still need to return a label that is not bound now, but

  // will eventually be bound. Any lable will do, as it will only act as

  // a placeholder, so we return the _continuation label.

  return Compile::current()->in_scratch_emit_size() ? &_continuation : &_entry;

}

Label* ZLoadBarrierStubC2::continuation() {

  return &_continuation;

}

void* ZBarrierSetC2::create_barrier_state(Arena* comp_arena) const {

  return new (comp_arena) ZBarrierSetC2State(comp_arena);

}

void ZBarrierSetC2::late_barrier_analysis() const {

  analyze_dominating_barriers();

  compute_liveness_at_stubs();

}

void ZBarrierSetC2::emit_stubs(CodeBuffer& cb) const {

  MacroAssembler masm(&cb);

  GrowableArray<ZLoadBarrierStubC2*>* const stubs = barrier_set_state()->stubs();

  for (int i = 0; i < stubs->length(); i++) {

    // Make sure there is enough space in the code buffer

    if (cb.insts()->maybe_expand_to_ensure_remaining(Compile::MAX_inst_size) && cb.blob() == NULL) {

      ciEnv::current()->record_failure("CodeCache is full");

      return;

    }

    ZBarrierSet::assembler()->generate_c2_load_barrier_stub(&masm, stubs->at(i));

  }

  masm.flush();

}

int ZBarrierSetC2::estimate_stub_size() const {

  Compile* const C = Compile::current();

  BufferBlob* const blob = C->scratch_buffer_blob();

  GrowableArray<ZLoadBarrierStubC2*>* const stubs = barrier_set_state()->stubs();

  int size = 0;

  for (int i = 0; i < stubs->length(); i++) {

    CodeBuffer cb(blob->content_begin(), (address)C->scratch_locs_memory() - blob->content_begin());

    MacroAssembler masm(&cb);

    ZBarrierSet::assembler()->generate_c2_load_barrier_stub(&masm, stubs->at(i));

    size += cb.insts_size();

  }

  return size;

}

static bool barrier_needed(C2Access& access) {

  return ZBarrierSet::barrier_needed(access.decorators(), access.type());

}

Node* ZBarrierSetC2::load_at_resolved(C2Access& access, const Type* val_type) const {

  Node* result = BarrierSetC2::load_at_resolved(access, val_type);

  if (barrier_needed(access) && access.raw_access()->is_Mem()) {

    if ((access.decorators() & ON_WEAK_OOP_REF) != 0) {

      access.raw_access()->as_Load()->set_barrier_data(ZLoadBarrierWeak);

    } else {

      access.raw_access()->as_Load()->set_barrier_data(ZLoadBarrierStrong);

    }

  }

  return result;

}

Node* ZBarrierSetC2::atomic_cmpxchg_val_at_resolved(C2AtomicParseAccess& access, Node* expected_val,

                                                    Node* new_val, const Type* val_type) const {

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

  if (barrier_needed(access)) {

    access.raw_access()->as_LoadStore()->set_barrier_data(ZLoadBarrierStrong);

  }

  return result;

}

Node* ZBarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicParseAccess& access, Node* expected_val,

                                                     Node* new_val, const Type* value_type) const {

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

  if (barrier_needed(access)) {

    access.raw_access()->as_LoadStore()->set_barrier_data(ZLoadBarrierStrong);

  }

  return result;

}

Node* ZBarrierSetC2::atomic_xchg_at_resolved(C2AtomicParseAccess& access, Node* new_val, const Type* val_type) const {

  Node* result = BarrierSetC2::atomic_xchg_at_resolved(access, new_val, val_type);

  if (barrier_needed(access)) {

    access.raw_access()->as_LoadStore()->set_barrier_data(ZLoadBarrierStrong);

  }

  return result;

}

bool ZBarrierSetC2::array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type,

                                                    bool is_clone, ArrayCopyPhase phase) const {

  return type == T_OBJECT || type == T_ARRAY;

}

// == Dominating barrier elision ==

static bool block_has_safepoint(const Block* block, uint from, uint to) {

  for (uint i = from; i < to; i++) {

    if (block->get_node(i)->is_MachSafePoint()) {

      // Safepoint found

      return true;

    }

  }

  // Safepoint not found

  return false;

}

static bool block_has_safepoint(const Block* block) {

  return block_has_safepoint(block, 0, block->number_of_nodes());

}

static uint block_index(const Block* block, const Node* node) {

  for (uint j = 0; j < block->number_of_nodes(); ++j) {

    if (block->get_node(j) == node) {

      return j;

    }

  }

  ShouldNotReachHere();

  return 0;

}

void ZBarrierSetC2::analyze_dominating_barriers() const {

  ResourceMark rm;

  Compile* const C = Compile::current();

  PhaseCFG* const cfg = C->cfg();

  Block_List worklist;

  Node_List mem_ops;

  Node_List barrier_loads;

  // Step 1 - Find accesses, and track them in lists

  for (uint i = 0; i < cfg->number_of_blocks(); ++i) {

    const Block* const block = cfg->get_block(i);

    for (uint j = 0; j < block->number_of_nodes(); ++j) {

      const Node* const node = block->get_node(j);

      if (!node->is_Mach()) {

        continue;

      }

      MachNode* const mach = node->as_Mach();

      switch (mach->ideal_Opcode()) {

      case Op_LoadP:

      case Op_CompareAndExchangeP:

      case Op_CompareAndSwapP:

      case Op_GetAndSetP:

        if (mach->barrier_data() == ZLoadBarrierStrong) {

          barrier_loads.push(mach);

        }

      case Op_StoreP:

        mem_ops.push(mach);

        break;

      default:

        break;

      }

    }

  }

  // Step 2 - Find dominating accesses for each load

  for (uint i = 0; i < barrier_loads.size(); i++) {

    MachNode* const load = barrier_loads.at(i)->as_Mach();

    const TypePtr* load_adr_type = NULL;

    intptr_t load_offset = 0;

    const Node* const load_obj = load->get_base_and_disp(load_offset, load_adr_type);

    Block* const load_block = cfg->get_block_for_node(load);

    const uint load_index = block_index(load_block, load);

    for (uint j = 0; j < mem_ops.size(); j++) {

      MachNode* mem = mem_ops.at(j)->as_Mach();

      const TypePtr* mem_adr_type = NULL;

      intptr_t mem_offset = 0;

      const Node* mem_obj = mem_obj = mem->get_base_and_disp(mem_offset, mem_adr_type);

      Block* mem_block = cfg->get_block_for_node(mem);

      uint mem_index = block_index(mem_block, mem);

      if (load_obj == NodeSentinel || mem_obj == NodeSentinel ||

          load_obj == NULL || mem_obj == NULL ||

          load_offset < 0 || mem_offset < 0) {

        continue;

      }

      if (mem_obj != load_obj || mem_offset != load_offset) {

        // Not the same addresses, not a candidate

        continue;

      }

      if (load_block == mem_block) {

        // Earlier accesses in the same block

        if (mem_index < load_index && !block_has_safepoint(mem_block, mem_index + 1, load_index)) {

          load->set_barrier_data(ZLoadBarrierElided);

        }

      } else if (mem_block->dominates(load_block)) {

        // Dominating block? Look around for safepoints

        ResourceMark rm;

        Block_List stack;

        VectorSet visited(Thread::current()->resource_area());

        stack.push(load_block);

        bool safepoint_found = block_has_safepoint(load_block);

        while (!safepoint_found && stack.size() > 0) {

          Block* block = stack.pop();

          if (visited.test_set(block->_pre_order)) {

            continue;

          }

          if (block_has_safepoint(block)) {

            safepoint_found = true;

            break;

          }

          if (block == mem_block) {

            continue;

          }

          // Push predecessor blocks

          for (uint p = 1; p < block->num_preds(); ++p) {

            Block* pred = cfg->get_block_for_node(block->pred(p));

            stack.push(pred);

          }

        }

        if (!safepoint_found) {

          load->set_barrier_data(ZLoadBarrierElided);

        }

      }

    }

  }

}

// == Reduced spilling optimization ==

void ZBarrierSetC2::compute_liveness_at_stubs() const {

  ResourceMark rm;

  Compile* const C = Compile::current();

  Arena* const A = Thread::current()->resource_area();

  PhaseCFG* const cfg = C->cfg();

  PhaseRegAlloc* const regalloc = C->regalloc();

  RegMask* const live = NEW_ARENA_ARRAY(A, RegMask, cfg->number_of_blocks() * sizeof(RegMask));

  ZBarrierSetAssembler* const bs = ZBarrierSet::assembler();

  Block_List worklist;

  for (uint i = 0; i < cfg->number_of_blocks(); ++i) {

    new ((void*)(live + i)) RegMask();

    worklist.push(cfg->get_block(i));

  }

  while (worklist.size() > 0) {

    const Block* const block = worklist.pop();

    RegMask& old_live = live[block->_pre_order];

    RegMask new_live;

    // Initialize to union of successors

    for (uint i = 0; i < block->_num_succs; i++) {

      const uint succ_id = block->_succs[i]->_pre_order;

      new_live.OR(live[succ_id]);

    }

    // Walk block backwards, computing liveness

    for (int i = block->number_of_nodes() - 1; i >= 0; --i) {

      const Node* const node = block->get_node(i);

      // Remove def bits

      const OptoReg::Name first = bs->refine_register(node, regalloc->get_reg_first(node));

      const OptoReg::Name second = bs->refine_register(node, regalloc->get_reg_second(node));

      if (first != OptoReg::Bad) {

        new_live.Remove(first);

      }

      if (second != OptoReg::Bad) {

        new_live.Remove(second);

      }

      // Add use bits

      for (uint j = 1; j < node->req(); ++j) {

        const Node* const use = node->in(j);

        const OptoReg::Name first = bs->refine_register(use, regalloc->get_reg_first(use));

        const OptoReg::Name second = bs->refine_register(use, regalloc->get_reg_second(use));

        if (first != OptoReg::Bad) {

          new_live.Insert(first);

        }

        if (second != OptoReg::Bad) {

          new_live.Insert(second);

        }

      }

      // If this node tracks liveness, update it

      RegMask* const regs = barrier_set_state()->live(node);

      if (regs != NULL) {

        regs->OR(new_live);

      }

    }

    // Now at block top, see if we have any changes

    new_live.SUBTRACT(old_live);

    if (new_live.is_NotEmpty()) {

      // Liveness has refined, update and propagate to prior blocks

      old_live.OR(new_live);

      for (uint i = 1; i < block->num_preds(); ++i) {

        Block* const pred = cfg->get_block_for_node(block->pred(i));

        worklist.push(pred);

      }

    }

  }

}