/*

 * Copyright (c) 1997, 2010, 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/cfgnode.hpp"

#include "opto/connode.hpp"

#include "opto/machnode.hpp"

#include "opto/mulnode.hpp"

#include "opto/phaseX.hpp"

#include "opto/subnode.hpp"

// Portions of code courtesy of Clifford Click

// Classic Add functionality.  This covers all the usual 'add' behaviors for

// an algebraic ring.  Add-integer, add-float, add-double, and binary-or are

// all inherited from this class.  The various identity values are supplied

// by virtual functions.

//=============================================================================

//------------------------------hash-------------------------------------------

// Hash function over AddNodes.  Needs to be commutative; i.e., I swap

// (commute) inputs to AddNodes willy-nilly so the hash function must return

// the same value in the presence of edge swapping.

uint AddNode::hash() const {

  return (uintptr_t)in(1) + (uintptr_t)in(2) + Opcode();

}

//------------------------------Identity---------------------------------------

// If either input is a constant 0, return the other input.

Node *AddNode::Identity( PhaseTransform *phase ) {

  const Type *zero = add_id();  // The additive identity

  if( phase->type( in(1) )->higher_equal( zero ) ) return in(2);

  if( phase->type( in(2) )->higher_equal( zero ) ) return in(1);

  return this;

}

//------------------------------commute----------------------------------------

// Commute operands to move loads and constants to the right.

static bool commute( Node *add, int con_left, int con_right ) {

  Node *in1 = add->in(1);

  Node *in2 = add->in(2);

  // Convert "1+x" into "x+1".

  // Right is a constant; leave it

  if( con_right ) return false;

  // Left is a constant; move it right.

  if( con_left ) {

    add->swap_edges(1, 2);

    return true;

  }

  // Convert "Load+x" into "x+Load".

  // Now check for loads

  if (in2->is_Load()) {

    if (!in1->is_Load()) {

      // already x+Load to return

      return false;

    }

    // both are loads, so fall through to sort inputs by idx

  } else if( in1->is_Load() ) {

    // Left is a Load and Right is not; move it right.

    add->swap_edges(1, 2);

    return true;

  }

  PhiNode *phi;

  // Check for tight loop increments: Loop-phi of Add of loop-phi

  if( in1->is_Phi() && (phi = in1->as_Phi()) && !phi->is_copy() && phi->region()->is_Loop() && phi->in(2)==add)

    return false;

  if( in2->is_Phi() && (phi = in2->as_Phi()) && !phi->is_copy() && phi->region()->is_Loop() && phi->in(2)==add){

    add->swap_edges(1, 2);

    return true;

  }

  // Otherwise, sort inputs (commutativity) to help value numbering.

  if( in1->_idx > in2->_idx ) {

    add->swap_edges(1, 2);

    return true;

  }

  return false;

}

//------------------------------Idealize---------------------------------------

// If we get here, we assume we are associative!

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

  const Type *t1 = phase->type( in(1) );

  const Type *t2 = phase->type( in(2) );

  int con_left  = t1->singleton();

  int con_right = t2->singleton();

  // Check for commutative operation desired

  if( commute(this,con_left,con_right) ) return this;

  AddNode *progress = NULL;             // Progress flag

  // Convert "(x+1)+2" into "x+(1+2)".  If the right input is a

  // constant, and the left input is an add of a constant, flatten the

  // expression tree.

  Node *add1 = in(1);

  Node *add2 = in(2);

  int add1_op = add1->Opcode();

  int this_op = Opcode();

  if( con_right && t2 != Type::TOP && // Right input is a constant?

      add1_op == this_op ) { // Left input is an Add?

    // Type of left _in right input

    const Type *t12 = phase->type( add1->in(2) );

    if( t12->singleton() && t12 != Type::TOP ) { // Left input is an add of a constant?

      // Check for rare case of closed data cycle which can happen inside

      // unreachable loops. In these cases the computation is undefined.

#ifdef ASSERT

      Node *add11    = add1->in(1);

      int   add11_op = add11->Opcode();

      if( (add1 == add1->in(1))

         || (add11_op == this_op && add11->in(1) == add1) ) {

        assert(false, "dead loop in AddNode::Ideal");

      }

#endif

      // The Add of the flattened expression

      Node *x1 = add1->in(1);

      Node *x2 = phase->makecon( add1->as_Add()->add_ring( t2, t12 ));

      PhaseIterGVN *igvn = phase->is_IterGVN();

      if( igvn ) {

        set_req_X(2,x2,igvn);

        set_req_X(1,x1,igvn);

      } else {

        set_req(2,x2);

        set_req(1,x1);

      }

      progress = this;            // Made progress

      add1 = in(1);

      add1_op = add1->Opcode();

    }

  }

  // Convert "(x+1)+y" into "(x+y)+1".  Push constants down the expression tree.

  if( add1_op == this_op && !con_right ) {

    Node *a12 = add1->in(2);

    const Type *t12 = phase->type( a12 );

    if( t12->singleton() && t12 != Type::TOP && (add1 != add1->in(1)) &&

       !(add1->in(1)->is_Phi() && add1->in(1)->as_Phi()->is_tripcount()) ) {

      assert(add1->in(1) != this, "dead loop in AddNode::Ideal");

      add2 = add1->clone();

      add2->set_req(2, in(2));

      add2 = phase->transform(add2);

      set_req(1, add2);

      set_req(2, a12);

      progress = this;

      add2 = a12;

    }

  }

  // Convert "x+(y+1)" into "(x+y)+1".  Push constants down the expression tree.

  int add2_op = add2->Opcode();

  if( add2_op == this_op && !con_left ) {

    Node *a22 = add2->in(2);

    const Type *t22 = phase->type( a22 );

    if( t22->singleton() && t22 != Type::TOP && (add2 != add2->in(1)) &&

       !(add2->in(1)->is_Phi() && add2->in(1)->as_Phi()->is_tripcount()) ) {

      assert(add2->in(1) != this, "dead loop in AddNode::Ideal");

      Node *addx = add2->clone();

      addx->set_req(1, in(1));

      addx->set_req(2, add2->in(1));

      addx = phase->transform(addx);

      set_req(1, addx);

      set_req(2, a22);

      progress = this;

    }

  }

  return progress;

}

//------------------------------Value-----------------------------------------

// An add node sums it's two _in.  If one input is an RSD, we must mixin

// the other input's symbols.

const Type *AddNode::Value( PhaseTransform *phase ) const {

  // Either input is TOP ==> the result is TOP

  const Type *t1 = phase->type( in(1) );

  const Type *t2 = phase->type( in(2) );

  if( t1 == Type::TOP ) return Type::TOP;

  if( t2 == Type::TOP ) return Type::TOP;

  // Either input is BOTTOM ==> the result is the local BOTTOM

  const Type *bot = bottom_type();

  if( (t1 == bot) || (t2 == bot) ||

      (t1 == Type::BOTTOM) || (t2 == Type::BOTTOM) )

    return bot;

  // Check for an addition involving the additive identity

  const Type *tadd = add_of_identity( t1, t2 );

  if( tadd ) return tadd;

  return add_ring(t1,t2);               // Local flavor of type addition

}

//------------------------------add_identity-----------------------------------

// Check for addition of the identity

const Type *AddNode::add_of_identity( const Type *t1, const Type *t2 ) const {

  const Type *zero = add_id();  // The additive identity

  if( t1->higher_equal( zero ) ) return t2;

  if( t2->higher_equal( zero ) ) return t1;

  return NULL;

}

//=============================================================================

//------------------------------Idealize---------------------------------------

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

  Node* in1 = in(1);

  Node* in2 = in(2);

  int op1 = in1->Opcode();

  int op2 = in2->Opcode();

  // Fold (con1-x)+con2 into (con1+con2)-x

  if ( op1 == Op_AddI && op2 == Op_SubI ) {

    // Swap edges to try optimizations below

    in1 = in2;

    in2 = in(1);

    op1 = op2;

    op2 = in2->Opcode();

  }

  if( op1 == Op_SubI ) {

    const Type *t_sub1 = phase->type( in1->in(1) );

    const Type *t_2    = phase->type( in2        );

    if( t_sub1->singleton() && t_2->singleton() && t_sub1 != Type::TOP && t_2 != Type::TOP )

      return new (phase->C, 3) SubINode(phase->makecon( add_ring( t_sub1, t_2 ) ),

                              in1->in(2) );

    // Convert "(a-b)+(c-d)" into "(a+c)-(b+d)"

    if( op2 == Op_SubI ) {

      // Check for dead cycle: d = (a-b)+(c-d)

      assert( in1->in(2) != this && in2->in(2) != this,

              "dead loop in AddINode::Ideal" );

      Node *sub  = new (phase->C, 3) SubINode(NULL, NULL);

      sub->init_req(1, phase->transform(new (phase->C, 3) AddINode(in1->in(1), in2->in(1) ) ));

      sub->init_req(2, phase->transform(new (phase->C, 3) AddINode(in1->in(2), in2->in(2) ) ));

      return sub;

    }

    // Convert "(a-b)+(b+c)" into "(a+c)"

    if( op2 == Op_AddI && in1->in(2) == in2->in(1) ) {

      assert(in1->in(1) != this && in2->in(2) != this,"dead loop in AddINode::Ideal");

      return new (phase->C, 3) AddINode(in1->in(1), in2->in(2));

    }

    // Convert "(a-b)+(c+b)" into "(a+c)"

    if( op2 == Op_AddI && in1->in(2) == in2->in(2) ) {

      assert(in1->in(1) != this && in2->in(1) != this,"dead loop in AddINode::Ideal");

      return new (phase->C, 3) AddINode(in1->in(1), in2->in(1));

    }

    // Convert "(a-b)+(b-c)" into "(a-c)"

    if( op2 == Op_SubI && in1->in(2) == in2->in(1) ) {

      assert(in1->in(1) != this && in2->in(2) != this,"dead loop in AddINode::Ideal");

      return new (phase->C, 3) SubINode(in1->in(1), in2->in(2));

    }

    // Convert "(a-b)+(c-a)" into "(c-b)"

    if( op2 == Op_SubI && in1->in(1) == in2->in(2) ) {

      assert(in1->in(2) != this && in2->in(1) != this,"dead loop in AddINode::Ideal");

      return new (phase->C, 3) SubINode(in2->in(1), in1->in(2));

    }

  }

  // Convert "x+(0-y)" into "(x-y)"

  if( op2 == Op_SubI && phase->type(in2->in(1)) == TypeInt::ZERO )

    return new (phase->C, 3) SubINode(in1, in2->in(2) );

  // Convert "(0-y)+x" into "(x-y)"

  if( op1 == Op_SubI && phase->type(in1->in(1)) == TypeInt::ZERO )

    return new (phase->C, 3) SubINode( in2, in1->in(2) );

  // Convert (x>>>z)+y into (x+(y<<z))>>>z for small constant z and y.

  // Helps with array allocation math constant folding

  // See 4790063:

  // Unrestricted transformation is unsafe for some runtime values of 'x'

  // ( x ==  0, z == 1, y == -1 ) fails

  // ( x == -5, z == 1, y ==  1 ) fails

  // Transform works for small z and small negative y when the addition

  // (x + (y << z)) does not cross zero.

  // Implement support for negative y and (x >= -(y << z))

  // Have not observed cases where type information exists to support

  // positive y and (x <= -(y << z))

  if( op1 == Op_URShiftI && op2 == Op_ConI &&

      in1->in(2)->Opcode() == Op_ConI ) {

    jint z = phase->type( in1->in(2) )->is_int()->get_con() & 0x1f; // only least significant 5 bits matter

    jint y = phase->type( in2 )->is_int()->get_con();

    if( z < 5 && -5 < y && y < 0 ) {

      const Type *t_in11 = phase->type(in1->in(1));

      if( t_in11 != Type::TOP && (t_in11->is_int()->_lo >= -(y << z)) ) {

        Node *a = phase->transform( new (phase->C, 3) AddINode( in1->in(1), phase->intcon(y<<z) ) );

        return new (phase->C, 3) URShiftINode( a, in1->in(2) );

      }

    }

  }

  return AddNode::Ideal(phase, can_reshape);

}

//------------------------------Identity---------------------------------------

// Fold (x-y)+y  OR  y+(x-y)  into  x

Node *AddINode::Identity( PhaseTransform *phase ) {

  if( in(1)->Opcode() == Op_SubI && phase->eqv(in(1)->in(2),in(2)) ) {

    return in(1)->in(1);

  }

  else if( in(2)->Opcode() == Op_SubI && phase->eqv(in(2)->in(2),in(1)) ) {

    return in(2)->in(1);

  }

  return AddNode::Identity(phase);

}

//------------------------------add_ring---------------------------------------

// Supplied function returns the sum of the inputs.  Guaranteed never

// to be passed a TOP or BOTTOM type, these are filtered out by

// pre-check.

const Type *AddINode::add_ring( const Type *t0, const Type *t1 ) const {

  const TypeInt *r0 = t0->is_int(); // Handy access

  const TypeInt *r1 = t1->is_int();

  int lo = r0->_lo + r1->_lo;

  int hi = r0->_hi + r1->_hi;

  if( !(r0->is_con() && r1->is_con()) ) {

    // Not both constants, compute approximate result

    if( (r0->_lo & r1->_lo) < 0 && lo >= 0 ) {

      lo = min_jint; hi = max_jint; // Underflow on the low side

    }

    if( (~(r0->_hi | r1->_hi)) < 0 && hi < 0 ) {

      lo = min_jint; hi = max_jint; // Overflow on the high side

    }

    if( lo > hi ) {               // Handle overflow

      lo = min_jint; hi = max_jint;

    }

  } else {

    // both constants, compute precise result using 'lo' and 'hi'

    // Semantics define overflow and underflow for integer addition

    // as expected.  In particular: 0x80000000 + 0x80000000 --> 0x0

  }

  return TypeInt::make( lo, hi, MAX2(r0->_widen,r1->_widen) );

}

//=============================================================================

//------------------------------Idealize---------------------------------------

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

  Node* in1 = in(1);

  Node* in2 = in(2);

  int op1 = in1->Opcode();

  int op2 = in2->Opcode();

  // Fold (con1-x)+con2 into (con1+con2)-x

  if ( op1 == Op_AddL && op2 == Op_SubL ) {

    // Swap edges to try optimizations below

    in1 = in2;

    in2 = in(1);

    op1 = op2;

    op2 = in2->Opcode();

  }

  // Fold (con1-x)+con2 into (con1+con2)-x

  if( op1 == Op_SubL ) {

    const Type *t_sub1 = phase->type( in1->in(1) );

    const Type *t_2    = phase->type( in2        );

    if( t_sub1->singleton() && t_2->singleton() && t_sub1 != Type::TOP && t_2 != Type::TOP )

      return new (phase->C, 3) SubLNode(phase->makecon( add_ring( t_sub1, t_2 ) ),

                              in1->in(2) );

    // Convert "(a-b)+(c-d)" into "(a+c)-(b+d)"

    if( op2 == Op_SubL ) {

      // Check for dead cycle: d = (a-b)+(c-d)

      assert( in1->in(2) != this && in2->in(2) != this,

              "dead loop in AddLNode::Ideal" );

      Node *sub  = new (phase->C, 3) SubLNode(NULL, NULL);

      sub->init_req(1, phase->transform(new (phase->C, 3) AddLNode(in1->in(1), in2->in(1) ) ));

      sub->init_req(2, phase->transform(new (phase->C, 3) AddLNode(in1->in(2), in2->in(2) ) ));

      return sub;

    }

    // Convert "(a-b)+(b+c)" into "(a+c)"

    if( op2 == Op_AddL && in1->in(2) == in2->in(1) ) {

      assert(in1->in(1) != this && in2->in(2) != this,"dead loop in AddLNode::Ideal");

      return new (phase->C, 3) AddLNode(in1->in(1), in2->in(2));

    }

    // Convert "(a-b)+(c+b)" into "(a+c)"

    if( op2 == Op_AddL && in1->in(2) == in2->in(2) ) {

      assert(in1->in(1) != this && in2->in(1) != this,"dead loop in AddLNode::Ideal");

      return new (phase->C, 3) AddLNode(in1->in(1), in2->in(1));

    }

    // Convert "(a-b)+(b-c)" into "(a-c)"

    if( op2 == Op_SubL && in1->in(2) == in2->in(1) ) {

      assert(in1->in(1) != this && in2->in(2) != this,"dead loop in AddLNode::Ideal");

      return new (phase->C, 3) SubLNode(in1->in(1), in2->in(2));

    }

    // Convert "(a-b)+(c-a)" into "(c-b)"

    if( op2 == Op_SubL && in1->in(1) == in1->in(2) ) {

      assert(in1->in(2) != this && in2->in(1) != this,"dead loop in AddLNode::Ideal");

      return new (phase->C, 3) SubLNode(in2->in(1), in1->in(2));

    }

  }

  // Convert "x+(0-y)" into "(x-y)"

  if( op2 == Op_SubL && phase->type(in2->in(1)) == TypeLong::ZERO )

    return new (phase->C, 3) SubLNode( in1, in2->in(2) );

  // Convert "(0-y)+x" into "(x-y)"

  if( op1 == Op_SubL && phase->type(in1->in(1)) == TypeInt::ZERO )

    return new (phase->C, 3) SubLNode( in2, in1->in(2) );

  // Convert "X+X+X+X+X...+X+Y" into "k*X+Y" or really convert "X+(X+Y)"

  // into "(X<<1)+Y" and let shift-folding happen.

  if( op2 == Op_AddL &&

      in2->in(1) == in1 &&

      op1 != Op_ConL &&

      0 ) {

    Node *shift = phase->transform(new (phase->C, 3) LShiftLNode(in1,phase->intcon(1)));

    return new (phase->C, 3) AddLNode(shift,in2->in(2));

  }

  return AddNode::Ideal(phase, can_reshape);

}

//------------------------------Identity---------------------------------------

// Fold (x-y)+y  OR  y+(x-y)  into  x

Node *AddLNode::Identity( PhaseTransform *phase ) {

  if( in(1)->Opcode() == Op_SubL && phase->eqv(in(1)->in(2),in(2)) ) {

    return in(1)->in(1);

  }

  else if( in(2)->Opcode() == Op_SubL && phase->eqv(in(2)->in(2),in(1)) ) {

    return in(2)->in(1);

  }

  return AddNode::Identity(phase);

}

//------------------------------add_ring---------------------------------------

// Supplied function returns the sum of the inputs.  Guaranteed never

// to be passed a TOP or BOTTOM type, these are filtered out by

// pre-check.

const Type *AddLNode::add_ring( const Type *t0, const Type *t1 ) const {

  const TypeLong *r0 = t0->is_long(); // Handy access

  const TypeLong *r1 = t1->is_long();

  jlong lo = r0->_lo + r1->_lo;

  jlong hi = r0->_hi + r1->_hi;

  if( !(r0->is_con() && r1->is_con()) ) {

    // Not both constants, compute approximate result

    if( (r0->_lo & r1->_lo) < 0 && lo >= 0 ) {

      lo =min_jlong; hi = max_jlong; // Underflow on the low side

    }

    if( (~(r0->_hi | r1->_hi)) < 0 && hi < 0 ) {

      lo = min_jlong; hi = max_jlong; // Overflow on the high side

    }

    if( lo > hi ) {               // Handle overflow

      lo = min_jlong; hi = max_jlong;

    }

  } else {

    // both constants, compute precise result using 'lo' and 'hi'

    // Semantics define overflow and underflow for integer addition

    // as expected.  In particular: 0x80000000 + 0x80000000 --> 0x0

  }

  return TypeLong::make( lo, hi, MAX2(r0->_widen,r1->_widen) );

}

//=============================================================================

//------------------------------add_of_identity--------------------------------

// Check for addition of the identity

const Type *AddFNode::add_of_identity( const Type *t1, const Type *t2 ) const {

  // x ADD 0  should return x unless 'x' is a -zero

  //

  // const Type *zero = add_id();     // The additive identity

  // jfloat f1 = t1->getf();

  // jfloat f2 = t2->getf();

  //

  // if( t1->higher_equal( zero ) ) return t2;

  // if( t2->higher_equal( zero ) ) return t1;

  return NULL;

}

//------------------------------add_ring---------------------------------------

// Supplied function returns the sum of the inputs.

// This also type-checks the inputs for sanity.  Guaranteed never to

// be passed a TOP or BOTTOM type, these are filtered out by pre-check.

const Type *AddFNode::add_ring( const Type *t0, const Type *t1 ) const {

  // We must be adding 2 float constants.

  return TypeF::make( t0->getf() + t1->getf() );

}

//------------------------------Ideal------------------------------------------

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

  if( IdealizedNumerics && !phase->C->method()->is_strict() ) {

    return AddNode::Ideal(phase, can_reshape); // commutative and associative transforms

  }

  // Floating point additions are not associative because of boundary conditions (infinity)

  return commute(this,

                 phase->type( in(1) )->singleton(),

                 phase->type( in(2) )->singleton() ) ? this : NULL;