/*

 * Copyright (c) 2013, 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 "memory/allocation.inline.hpp"

#include "opto/addnode.hpp"

#include "opto/machnode.hpp"

#include "opto/mathexactnode.hpp"

#include "opto/matcher.hpp"

#include "opto/subnode.hpp"

MathExactNode::MathExactNode(Node* ctrl, Node* n1, Node* n2) : MultiNode(3) {

  init_req(0, ctrl);

  init_req(1, n1);

  init_req(2, n2);

}

Node* AddExactINode::match(const ProjNode* proj, const Matcher* m) {

  uint ideal_reg = proj->ideal_reg();

  RegMask rm;

  if (proj->_con == result_proj_node) {

    rm = m->mathExactI_result_proj_mask();

  } else {

    assert(proj->_con == flags_proj_node, "must be result or flags");

    assert(ideal_reg == Op_RegFlags, "sanity");

    rm = m->mathExactI_flags_proj_mask();

  }

  return new (m->C) MachProjNode(this, proj->_con, rm, ideal_reg);

}

// If the MathExactNode won't overflow we have to replace the

// FlagsProjNode and ProjNode that is generated by the MathExactNode

Node* MathExactNode::no_overflow(PhaseGVN *phase, Node* new_result) {

  PhaseIterGVN *igvn = phase->is_IterGVN();

  if (igvn) {

    ProjNode* result = result_node();

    ProjNode* flags = flags_node();

    if (result != NULL) {

      igvn->replace_node(result, new_result);

    }

    if (flags != NULL) {

      BoolNode* bolnode = (BoolNode *) flags->unique_out();

      switch (bolnode->_test._test) {

        case BoolTest::overflow:

          // if the check is for overflow - never taken

          igvn->replace_node(bolnode, phase->intcon(0));

          break;

        case BoolTest::no_overflow:

          // if the check is for no overflow - always taken

          igvn->replace_node(bolnode, phase->intcon(1));

          break;

        default:

          fatal("Unexpected value of BoolTest");

          break;

      }

      flags->del_req(0);

    }

  }

  return new_result;

}

Node *AddExactINode::Ideal(PhaseGVN *phase, bool can_reshape) {

  Node *arg1 = in(1);

  Node *arg2 = in(2);

  const Type* type1 = phase->type(arg1);

  const Type* type2 = phase->type(arg2);

  if (type1 != Type::TOP && type1->singleton() &&

      type2 != Type::TOP && type2->singleton()) {

    jint val1 = arg1->get_int();

    jint val2 = arg2->get_int();

    jint result = val1 + val2;

    // Hacker's Delight 2-12 Overflow if both arguments have the opposite sign of the result

    if ( (((val1 ^ result) & (val2 ^ result)) >= 0)) {

      Node* con_result = ConINode::make(phase->C, result);

      return no_overflow(phase, con_result);

    }

    return NULL;

  }

  if (type1 == TypeInt::ZERO) { // (Add 0 x) == x

    Node* add_result = new (phase->C) AddINode(arg1, arg2);

    return no_overflow(phase, add_result);

  }

  if (type2 == TypeInt::ZERO) { // (Add x 0) == x

    Node* add_result = new (phase->C) AddINode(arg1, arg2);

    return no_overflow(phase, add_result);

  }

  if (type2->singleton()) {

    return NULL; // no change - keep constant on the right

  }

  if (type1->singleton()) {

    // Make it x + Constant - move constant to the right

    swap_edges(1, 2);

    return this;

  }

  if (arg2->is_Load()) {

    return NULL; // no change - keep load on the right

  }

  if (arg1->is_Load()) {

    // Make it x + Load - move load to the right

    swap_edges(1, 2);

    return this;

  }

  if (arg1->_idx > arg2->_idx) {

    // Sort the edges

    swap_edges(1, 2);

    return this;

  }

  return NULL;

}