Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 1997-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

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  */

 // Portions of code courtesy of Clifford Click

 // Optimization - Graph Style

 #include "incls/_precompiled.incl"

 #include "incls/_subnode.cpp.incl"

 #include "math.h"

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

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

 // If right input is a constant 0, return the left input.

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

   assert(in(1) != this, "Must already have called Value");

   assert(in(2) != this, "Must already have called Value");

   // Remove double negation

   const Type *zero = add_id();

   if( phase->type( in(1) )->higher_equal( zero ) &&

       in(2)->Opcode() == Opcode() &&

       phase->type( in(2)->in(1) )->higher_equal( zero ) ) {

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

   }

   // Convert "(X+Y) - Y" into X

   if( in(1)->Opcode() == Op_AddI ) {

     if( phase->eqv(in(1)->in(2),in(2)) )

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

     // Also catch: "(X + Opaque2(Y)) - Y".  In this case, 'Y' is a loop-varying

     // trip counter and X is likely to be loop-invariant (that's how O2 Nodes

     // are originally used, although the optimizer sometimes jiggers things).

     // This folding through an O2 removes a loop-exit use of a loop-varying

     // value and generally lowers register pressure in and around the loop.

     if( in(1)->in(2)->Opcode() == Op_Opaque2 &&

         phase->eqv(in(1)->in(2)->in(1),in(2)) )

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

   }

   return ( phase->type( in(2) )->higher_equal( zero ) ) ? in(1) : this;

 }

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

 // A subtract node differences it's two inputs.

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

   const Node* in1 = in(1);

   const Node* in2 = in(2);

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

   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);

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

   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);

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

   // Not correct for SubFnode and AddFNode (must check for infinity)

   // Equal?  Subtract is zero

   if (phase->eqv_uncast(in1, in2))  return add_id();

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

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

     return bottom_type();

   return sub(t1,t2);            // Local flavor of type subtraction

 }

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

 //------------------------------Helper function--------------------------------

 static bool ok_to_convert(Node* inc, Node* iv) {

     // Do not collapse (x+c0)-y if "+" is a loop increment, because the

     // "-" is loop invariant and collapsing extends the live-range of "x"

     // to overlap with the "+", forcing another register to be used in

     // the loop.

     // This test will be clearer with '&&' (apply DeMorgan's rule)

     // but I like the early cutouts that happen here.

     const PhiNode *phi;

     if( ( !inc->in(1)->is_Phi() ||

           !(phi=inc->in(1)->as_Phi()) ||

           phi->is_copy() ||

           !phi->region()->is_CountedLoop() ||

           inc != phi->region()->as_CountedLoop()->incr() )

        &&

         // Do not collapse (x+c0)-iv if "iv" is a loop induction variable,

         // because "x" maybe invariant.

         ( !iv->is_loop_iv() )

       ) {

       return true;

     } else {

       return false;

     }

 }

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

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

   Node *in1 = in(1);

   Node *in2 = in(2);

   uint op1 = in1->Opcode();

   uint op2 = in2->Opcode();

 #ifdef ASSERT

   // Check for dead loop

   if( phase->eqv( in1, this ) || phase->eqv( in2, this ) ||

       ( op1 == Op_AddI || op1 == Op_SubI ) &&

       ( phase->eqv( in1->in(1), this ) || phase->eqv( in1->in(2), this ) ||

         phase->eqv( in1->in(1), in1  ) || phase->eqv( in1->in(2), in1 ) ) )

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

 #endif

   const Type *t2 = phase->type( in2 );

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

   // Convert "x-c0" into "x+ -c0".

   if( t2->base() == Type::Int ){        // Might be bottom or top...

     const TypeInt *i = t2->is_int();

     if( i->is_con() )

       return new (phase->C, 3) AddINode(in1, phase->intcon(-i->get_con()));

   }

   // Convert "(x+c0) - y" into (x-y) + c0"

   // Do not collapse (x+c0)-y if "+" is a loop increment or

   // if "y" is a loop induction variable.

   if( op1 == Op_AddI && ok_to_convert(in1, in2) ) {

     const Type *tadd = phase->type( in1->in(2) );

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

       Node *sub2 = phase->transform( new (phase->C, 3) SubINode( in1->in(1), in2 ));

       return new (phase->C, 3) AddINode( sub2, in1->in(2) );

     }

   }

   // Convert "x - (y+c0)" into "(x-y) - c0"

   // Need the same check as in above optimization but reversed.

   if (op2 == Op_AddI && ok_to_convert(in2, in1)) {

     Node* in21 = in2->in(1);

     Node* in22 = in2->in(2);

     const TypeInt* tcon = phase->type(in22)->isa_int();

     if (tcon != NULL && tcon->is_con()) {

       Node* sub2 = phase->transform( new (phase->C, 3) SubINode(in1, in21) );

       Node* neg_c0 = phase->intcon(- tcon->get_con());

       return new (phase->C, 3) AddINode(sub2, neg_c0);

     }

   }

   const Type *t1 = phase->type( in1 );

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

 #ifdef ASSERT

   // Check for dead loop

   if( ( op2 == Op_AddI || op2 == Op_SubI ) &&

       ( phase->eqv( in2->in(1), this ) || phase->eqv( in2->in(2), this ) ||

         phase->eqv( in2->in(1), in2  ) || phase->eqv( in2->in(2), in2  ) ) )

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

 #endif

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

   if( op2 == Op_AddI &&

       phase->eqv( in1, in2->in(1) ) )

     return new (phase->C, 3) SubINode( phase->intcon(0),in2->in(2));

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

   if( op1 == Op_SubI &&

       phase->eqv( in1->in(1), in2 ) )

     return new (phase->C, 3) SubINode( phase->intcon(0),in1->in(2));

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

   if( op2 == Op_AddI &&

       phase->eqv( in1, in2->in(2) ) )

     return new (phase->C, 3) SubINode( phase->intcon(0),in2->in(1));

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

   if( t1 == TypeInt::ZERO && op2 == Op_SubI )

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

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

   jint con;

   if( t1 == TypeInt::ZERO && op2 == Op_AddI &&

       (con = in2->in(2)->find_int_con(0)) != 0 )

     return new (phase->C, 3) SubINode( phase->intcon(-con), in2->in(1) );

   // Convert "(X+A) - (X+B)" into "A - B"

   if( op1 == Op_AddI && op2 == Op_AddI && in1->in(1) == in2->in(1) )

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

   // Convert "(A+X) - (B+X)" into "A - B"

   if( op1 == Op_AddI && op2 == Op_AddI && in1->in(2) == in2->in(2) )

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

   // Convert "A-(B-C)" into (A+C)-B", since add is commutative and generally

   // nicer to optimize than subtract.

   if( op2 == Op_SubI && in2->outcnt() == 1) {

     Node *add1 = phase->transform( new (phase->C, 3) AddINode( in1, in2->in(2) ) );

     return new (phase->C, 3) SubINode( add1, in2->in(1) );

   }

   return NULL;

 }

 //------------------------------sub--------------------------------------------

 // A subtract node differences it's two inputs.

 const Type *SubINode::sub( const Type *t1, const Type *t2 ) const {

   const TypeInt *r0 = t1->is_int(); // Handy access

   const TypeInt *r1 = t2->is_int();

   int32 lo = r0->_lo - r1->_hi;

   int32 hi = r0->_hi - r1->_lo;

   // We next check for 32-bit overflow.

   // If that happens, we just assume all integers are possible.

   if( (((r0->_lo ^ r1->_hi) >= 0) ||    // lo ends have same signs OR

        ((r0->_lo ^      lo) >= 0)) &&   // lo results have same signs AND

       (((r0->_hi ^ r1->_lo) >= 0) ||    // hi ends have same signs OR

        ((r0->_hi ^      hi) >= 0)) )    // hi results have same signs

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

   else                          // Overflow; assume all integers

     return TypeInt::INT;

 }

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

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

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

   Node *in1 = in(1);

   Node *in2 = in(2);

   uint op1 = in1->Opcode();

   uint op2 = in2->Opcode();

 #ifdef ASSERT

   // Check for dead loop

   if( phase->eqv( in1, this ) || phase->eqv( in2, this ) ||

       ( op1 == Op_AddL || op1 == Op_SubL ) &&

       ( phase->eqv( in1->in(1), this ) || phase->eqv( in1->in(2), this ) ||

         phase->eqv( in1->in(1), in1  ) || phase->eqv( in1->in(2), in1  ) ) )

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

 #endif

   if( phase->type( in2 ) == Type::TOP ) return NULL;

   const TypeLong *i = phase->type( in2 )->isa_long();

   // Convert "x-c0" into "x+ -c0".

   if( i &&                      // Might be bottom or top...

       i->is_con() )

     return new (phase->C, 3) AddLNode(in1, phase->longcon(-i->get_con()));

   // Convert "(x+c0) - y" into (x-y) + c0"

   // Do not collapse (x+c0)-y if "+" is a loop increment or

   // if "y" is a loop induction variable.

   if( op1 == Op_AddL && ok_to_convert(in1, in2) ) {

     Node *in11 = in1->in(1);

     const Type *tadd = phase->type( in1->in(2) );

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

       Node *sub2 = phase->transform( new (phase->C, 3) SubLNode( in11, in2 ));

       return new (phase->C, 3) AddLNode( sub2, in1->in(2) );

     }

   }

   // Convert "x - (y+c0)" into "(x-y) - c0"

   // Need the same check as in above optimization but reversed.

   if (op2 == Op_AddL && ok_to_convert(in2, in1)) {

     Node* in21 = in2->in(1);

     Node* in22 = in2->in(2);

     const TypeLong* tcon = phase->type(in22)->isa_long();

     if (tcon != NULL && tcon->is_con()) {

       Node* sub2 = phase->transform( new (phase->C, 3) SubLNode(in1, in21) );

       Node* neg_c0 = phase->longcon(- tcon->get_con());

       return new (phase->C, 3) AddLNode(sub2, neg_c0);

     }

   }

   const Type *t1 = phase->type( in1 );

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

 #ifdef ASSERT

   // Check for dead loop

   if( ( op2 == Op_AddL || op2 == Op_SubL ) &&

       ( phase->eqv( in2->in(1), this ) || phase->eqv( in2->in(2), this ) ||

         phase->eqv( in2->in(1), in2  ) || phase->eqv( in2->in(2), in2  ) ) )

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

 #endif

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

   if( op2 == Op_AddL &&

       phase->eqv( in1, in2->in(1) ) )

     return new (phase->C, 3) SubLNode( phase->makecon(TypeLong::ZERO), in2->in(2));

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

   if( op2 == Op_AddL &&

       phase->eqv( in1, in2->in(2) ) )

     return new (phase->C, 3) SubLNode( phase->makecon(TypeLong::ZERO),in2->in(1));

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

   if( phase->type( in1 ) == TypeLong::ZERO && op2 == Op_SubL )

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

   // Convert "(X+A) - (X+B)" into "A - B"

   if( op1 == Op_AddL && op2 == Op_AddL && in1->in(1) == in2->in(1) )

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

   // Convert "(A+X) - (B+X)" into "A - B"

   if( op1 == Op_AddL && op2 == Op_AddL && in1->in(2) == in2->in(2) )

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

   // Convert "A-(B-C)" into (A+C)-B"

   if( op2 == Op_SubL && in2->outcnt() == 1) {

     Node *add1 = phase->transform( new (phase->C, 3) AddLNode( in1, in2->in(2) ) );

     return new (phase->C, 3) SubLNode( add1, in2->in(1) );

   }

   return NULL;

 }

 //------------------------------sub--------------------------------------------

 // A subtract node differences it's two inputs.

 const Type *SubLNode::sub( const Type *t1, const Type *t2 ) const {

   const TypeLong *r0 = t1->is_long(); // Handy access

   const TypeLong *r1 = t2->is_long();

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

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

   // We next check for 32-bit overflow.

   // If that happens, we just assume all integers are possible.

   if( (((r0->_lo ^ r1->_hi) >= 0) ||    // lo ends have same signs OR

        ((r0->_lo ^      lo) >= 0)) &&   // lo results have same signs AND

       (((r0->_hi ^ r1->_lo) >= 0) ||    // hi ends have same signs OR

        ((r0->_hi ^      hi) >= 0)) )    // hi results have same signs

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

   else                          // Overflow; assume all integers

     return TypeLong::LONG;

 }

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

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

 // A subtract node differences its two inputs.

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

   const Node* in1 = in(1);

   const Node* in2 = in(2);

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

   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);

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

   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);

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

   // if both operands are infinity of same sign, the result is NaN; do

   // not replace with zero

   if( (t1->is_finite() && t2->is_finite()) ) {

     if( phase->eqv(in1, in2) ) return add_id();

   }

   // 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;

   return sub(t1,t2);            // Local flavor of type subtraction

 }

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

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

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

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

   // Convert "x-c0" into "x+ -c0".

   if( t2->base() == Type::FloatCon ) {  // Might be bottom or top...

     // return new (phase->C, 3) AddFNode(in(1), phase->makecon( TypeF::make(-t2->getf()) ) );

   }

   // Not associative because of boundary conditions (infinity)

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

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

     if( in(2)->is_Add() &&

         phase->eqv(in(1),in(2)->in(1) ) )

       return new (phase->C, 3) SubFNode( phase->makecon(TypeF::ZERO),in(2)->in(2));

   }

   // Cannot replace 0.0-X with -X because a 'fsub' bytecode computes

   // 0.0-0.0 as +0.0, while a 'fneg' bytecode computes -0.0.

   //if( phase->type(in(1)) == TypeF::ZERO )

   //return new (phase->C, 2) NegFNode(in(2));

   return NULL;

 }

 //------------------------------sub--------------------------------------------

 // A subtract node differences its two inputs.

 const Type *SubFNode::sub( const Type *t1, const Type *t2 ) const {

   // no folding if one of operands is infinity or NaN, do not do constant folding

   if( g_isfinite(t1->getf()) && g_isfinite(t2->getf()) ) {

     return TypeF::make( t1->getf() - t2->getf() );

   }

   else if( g_isnan(t1->getf()) ) {

     return t1;

   }

   else if( g_isnan(t2->getf()) ) {

     return t2;

   }

   else {

     return Type::FLOAT;

   }

 }

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

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

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

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

   // Convert "x-c0" into "x+ -c0".

   if( t2->base() == Type::DoubleCon ) { // Might be bottom or top...

     // return new (phase->C, 3) AddDNode(in(1), phase->makecon( TypeD::make(-t2->getd()) ) );

   }

   // Not associative because of boundary conditions (infinity)

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

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

     if( in(2)->is_Add() &&

         phase->eqv(in(1),in(2)->in(1) ) )

       return new (phase->C, 3) SubDNode( phase->makecon(TypeD::ZERO),in(2)->in(2));

   }

   // Cannot replace 0.0-X with -X because a 'dsub' bytecode computes

   // 0.0-0.0 as +0.0, while a 'dneg' bytecode computes -0.0.

   //if( phase->type(in(1)) == TypeD::ZERO )

   //return new (phase->C, 2) NegDNode(in(2));

   return NULL;

 }

 //------------------------------sub--------------------------------------------

 // A subtract node differences its two inputs.

 const Type *SubDNode::sub( const Type *t1, const Type *t2 ) const {

   // no folding if one of operands is infinity or NaN, do not do constant folding

   if( g_isfinite(t1->getd()) && g_isfinite(t2->getd()) ) {

     return TypeD::make( t1->getd() - t2->getd() );

   }

   else if( g_isnan(t1->getd()) ) {

     return t1;

   }

   else if( g_isnan(t2->getd()) ) {

     return t2;

   }

   else {

     return Type::DOUBLE;

   }

 }

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

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

 // Unlike SubNodes, compare must still flatten return value to the

 // range -1, 0, 1.

 // And optimizations like those for (X + Y) - X fail if overflow happens.

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

   return this;

 }

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

 //------------------------------cmp--------------------------------------------

 // Simplify a CmpI (compare 2 integers) node, based on local information.

 // If both inputs are constants, compare them.

 const Type *CmpINode::sub( const Type *t1, const Type *t2 ) const {

   const TypeInt *r0 = t1->is_int(); // Handy access

   const TypeInt *r1 = t2->is_int();

   if( r0->_hi < r1->_lo )       // Range is always low?

     return TypeInt::CC_LT;

   else if( r0->_lo > r1->_hi )  // Range is always high?

     return TypeInt::CC_GT;

   else if( r0->is_con() && r1->is_con() ) { // comparing constants?

     assert(r0->get_con() == r1->get_con(), "must be equal");

     return TypeInt::CC_EQ;      // Equal results.

   } else if( r0->_hi == r1->_lo ) // Range is never high?

     return TypeInt::CC_LE;

   else if( r0->_lo == r1->_hi ) // Range is never low?

     return TypeInt::CC_GE;

   return TypeInt::CC;           // else use worst case results

 }

 // Simplify a CmpU (compare 2 integers) node, based on local information.

 // If both inputs are constants, compare them.

 const Type *CmpUNode::sub( const Type *t1, const Type *t2 ) const {

   assert(!t1->isa_ptr(), "obsolete usage of CmpU");

   // comparing two unsigned ints

   const TypeInt *r0 = t1->is_int();   // Handy access

   const TypeInt *r1 = t2->is_int();

   // Current installed version

   // Compare ranges for non-overlap

   juint lo0 = r0->_lo;

   juint hi0 = r0->_hi;

   juint lo1 = r1->_lo;

   juint hi1 = r1->_hi;

   // If either one has both negative and positive values,

   // it therefore contains both 0 and -1, and since [0..-1] is the

   // full unsigned range, the type must act as an unsigned bottom.

   bool bot0 = ((jint)(lo0 ^ hi0) < 0);

   bool bot1 = ((jint)(lo1 ^ hi1) < 0);

   if (bot0 || bot1) {

     // All unsigned values are LE -1 and GE 0.

     if (lo0 == 0 && hi0 == 0) {

       return TypeInt::CC_LE;            //   0 <= bot

     } else if (lo1 == 0 && hi1 == 0) {

       return TypeInt::CC_GE;            // bot >= 0

     }

   } else {

     // We can use ranges of the form [lo..hi] if signs are the same.

     assert(lo0 <= hi0 && lo1 <= hi1, "unsigned ranges are valid");

     // results are reversed, '-' > '+' for unsigned compare

     if (hi0 < lo1) {

       return TypeInt::CC_LT;            // smaller

     } else if (lo0 > hi1) {

       return TypeInt::CC_GT;            // greater

     } else if (hi0 == lo1 && lo0 == hi1) {

       return TypeInt::CC_EQ;            // Equal results

     } else if (lo0 >= hi1) {

       return TypeInt::CC_GE;

     } else if (hi0 <= lo1) {

       // Check for special case in Hashtable::get.  (See below.)

       if ((jint)lo0 >= 0 && (jint)lo1 >= 0 &&

           in(1)->Opcode() == Op_ModI &&

           in(1)->in(2) == in(2) )

         return TypeInt::CC_LT;

       return TypeInt::CC_LE;

     }

   }

   // Check for special case in Hashtable::get - the hash index is

   // mod'ed to the table size so the following range check is useless.

   // Check for: (X Mod Y) CmpU Y, where the mod result and Y both have

   // to be positive.

   // (This is a gross hack, since the sub method never

   // looks at the structure of the node in any other case.)

   if ((jint)lo0 >= 0 && (jint)lo1 >= 0 &&

       in(1)->Opcode() == Op_ModI &&

       in(1)->in(2)->uncast() == in(2)->uncast())

     return TypeInt::CC_LT;

   return TypeInt::CC;                   // else use worst case results

 }

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

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

   if (phase->type(in(2))->higher_equal(TypeInt::ZERO)) {

     switch (in(1)->Opcode()) {

     case Op_CmpL3:              // Collapse a CmpL3/CmpI into a CmpL

       return new (phase->C, 3) CmpLNode(in(1)->in(1),in(1)->in(2));

     case Op_CmpF3:              // Collapse a CmpF3/CmpI into a CmpF

       return new (phase->C, 3) CmpFNode(in(1)->in(1),in(1)->in(2));

     case Op_CmpD3:              // Collapse a CmpD3/CmpI into a CmpD

       return new (phase->C, 3) CmpDNode(in(1)->in(1),in(1)->in(2));

     //case Op_SubI:

       // If (x - y) cannot overflow, then ((x - y) <?> 0)

       // can be turned into (x <?> y).

       // This is handled (with more general cases) by Ideal_sub_algebra.

     }

   }

   return NULL;                  // No change

 }

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

 // Simplify a CmpL (compare 2 longs ) node, based on local information.

 // If both inputs are constants, compare them.

 const Type *CmpLNode::sub( const Type *t1, const Type *t2 ) const {

   const TypeLong *r0 = t1->is_long(); // Handy access

   const TypeLong *r1 = t2->is_long();

   if( r0->_hi < r1->_lo )       // Range is always low?

     return TypeInt::CC_LT;

   else if( r0->_lo > r1->_hi )  // Range is always high?

     return TypeInt::CC_GT;

   else if( r0->is_con() && r1->is_con() ) { // comparing constants?

     assert(r0->get_con() == r1->get_con(), "must be equal");

     return TypeInt::CC_EQ;      // Equal results.

   } else if( r0->_hi == r1->_lo ) // Range is never high?

     return TypeInt::CC_LE;

   else if( r0->_lo == r1->_hi ) // Range is never low?

     return TypeInt::CC_GE;

   return TypeInt::CC;           // else use worst case results

 }

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

 //------------------------------sub--------------------------------------------

 // Simplify an CmpP (compare 2 pointers) node, based on local information.

 // If both inputs are constants, compare them.

 const Type *CmpPNode::sub( const Type *t1, const Type *t2 ) const {

   const TypePtr *r0 = t1->is_ptr(); // Handy access

   const TypePtr *r1 = t2->is_ptr();

   // Undefined inputs makes for an undefined result

   if( TypePtr::above_centerline(r0->_ptr) ||

       TypePtr::above_centerline(r1->_ptr) )

     return Type::TOP;

   if (r0 == r1 && r0->singleton()) {

     // Equal pointer constants (klasses, nulls, etc.)

     return TypeInt::CC_EQ;

   }

   // See if it is 2 unrelated classes.

   const TypeOopPtr* p0 = r0->isa_oopptr();

   const TypeOopPtr* p1 = r1->isa_oopptr();

   if (p0 && p1) {

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

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

     AllocateNode* alloc1 = AllocateNode::Ideal_allocation(in1, NULL);

     AllocateNode* alloc2 = AllocateNode::Ideal_allocation(in2, NULL);

     if (MemNode::detect_ptr_independence(in1, alloc1, in2, alloc2, NULL)) {

       return TypeInt::CC_GT;  // different pointers

     }

     ciKlass* klass0 = p0->klass();

     bool    xklass0 = p0->klass_is_exact();

     ciKlass* klass1 = p1->klass();

     bool    xklass1 = p1->klass_is_exact();

     int kps = (p0->isa_klassptr()?1:0) + (p1->isa_klassptr()?1:0);

     if (klass0 && klass1 &&

         kps != 1 &&             // both or neither are klass pointers

         !klass0->is_interface() && // do not trust interfaces

         !klass1->is_interface()) {

       // See if neither subclasses the other, or if the class on top

       // is precise.  In either of these cases, the compare must fail.

       if (klass0->equals(klass1)   ||   // if types are unequal but klasses are

           !klass0->is_java_klass() ||   // types not part of Java language?

           !klass1->is_java_klass()) {   // types not part of Java language?

         // Do nothing; we know nothing for imprecise types

       } else if (klass0->is_subtype_of(klass1)) {

         // If klass1's type is PRECISE, then we can fail.

         if (xklass1)  return TypeInt::CC_GT;

       } else if (klass1->is_subtype_of(klass0)) {

         // If klass0's type is PRECISE, then we can fail.

         if (xklass0)  return TypeInt::CC_GT;

       } else {                  // Neither subtypes the other

         return TypeInt::CC_GT;  // ...so always fail

       }

     }

   }

   // Known constants can be compared exactly

   // Null can be distinguished from any NotNull pointers

   // Unknown inputs makes an unknown result

   if( r0->singleton() ) {

     intptr_t bits0 = r0->get_con();

     if( r1->singleton() )

       return bits0 == r1->get_con() ? TypeInt::CC_EQ : TypeInt::CC_GT;

     return ( r1->_ptr == TypePtr::NotNull && bits0==0 ) ? TypeInt::CC_GT : TypeInt::CC;

   } else if( r1->singleton() ) {

     intptr_t bits1 = r1->get_con();

     return ( r0->_ptr == TypePtr::NotNull && bits1==0 ) ? TypeInt::CC_GT : TypeInt::CC;

   } else

     return TypeInt::CC;

 }

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

 // Check for the case of comparing an unknown klass loaded from the primary

 // super-type array vs a known klass with no subtypes.  This amounts to

 // checking to see an unknown klass subtypes a known klass with no subtypes;

 // this only happens on an exact match.  We can shorten this test by 1 load.

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

   // Constant pointer on right?

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

   if (t2 == NULL || !t2->klass_is_exact())

     return NULL;

   // Get the constant klass we are comparing to.

   ciKlass* superklass = t2->klass();

   // Now check for LoadKlass on left.

   Node* ldk1 = in(1);

   if (ldk1->Opcode() != Op_LoadKlass)

     return NULL;

   // Take apart the address of the LoadKlass:

   Node* adr1 = ldk1->in(MemNode::Address);

   intptr_t con2 = 0;

   Node* ldk2 = AddPNode::Ideal_base_and_offset(adr1, phase, con2);

   if (ldk2 == NULL)

     return NULL;

   if (con2 == oopDesc::klass_offset_in_bytes()) {

     // We are inspecting an object's concrete class.

     // Short-circuit the check if the query is abstract.

     if (superklass->is_interface() ||

         superklass->is_abstract()) {

       // Make it come out always false:

       this->set_req(2, phase->makecon(TypePtr::NULL_PTR));

       return this;

     }

   }

   // Check for a LoadKlass from primary supertype array.

   // Any nested loadklass from loadklass+con must be from the p.s. array.

   if (ldk2->Opcode() != Op_LoadKlass)

     return NULL;

   // Verify that we understand the situation

   if (con2 != (intptr_t) superklass->super_check_offset())

     return NULL;                // Might be element-klass loading from array klass

   // If 'superklass' has no subklasses and is not an interface, then we are

   // assured that the only input which will pass the type check is

   // 'superklass' itself.

   //

   // We could be more liberal here, and allow the optimization on interfaces

   // which have a single implementor.  This would require us to increase the

   // expressiveness of the add_dependency() mechanism.

   // %%% Do this after we fix TypeOopPtr:  Deps are expressive enough now.

   // Object arrays must have their base element have no subtypes

   while (superklass->is_obj_array_klass()) {

     ciType* elem = superklass->as_obj_array_klass()->element_type();

     superklass = elem->as_klass();

   }

   if (superklass->is_instance_klass()) {

     ciInstanceKlass* ik = superklass->as_instance_klass();

     if (ik->has_subklass() || ik->is_interface())  return NULL;

     // Add a dependency if there is a chance that a subclass will be added later.

     if (!ik->is_final()) {

       phase->C->dependencies()->assert_leaf_type(ik);

     }

   }

   // Bypass the dependent load, and compare directly

   this->set_req(1,ldk2);

   return this;

 }

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

 //------------------------------sub--------------------------------------------

 // Simplify an CmpN (compare 2 pointers) node, based on local information.

 // If both inputs are constants, compare them.

 const Type *CmpNNode::sub( const Type *t1, const Type *t2 ) const {

   const TypePtr *r0 = t1->is_narrowoop()->make_oopptr(); // Handy access

   const TypePtr *r1 = t2->is_narrowoop()->make_oopptr();

   // Undefined inputs makes for an undefined result

   if( TypePtr::above_centerline(r0->_ptr) ||

       TypePtr::above_centerline(r1->_ptr) )

     return Type::TOP;

   if (r0 == r1 && r0->singleton()) {

     // Equal pointer constants (klasses, nulls, etc.)

     return TypeInt::CC_EQ;

   }

   // See if it is 2 unrelated classes.

   const TypeOopPtr* p0 = r0->isa_oopptr();

   const TypeOopPtr* p1 = r1->isa_oopptr();

   if (p0 && p1) {

     ciKlass* klass0 = p0->klass();

     bool    xklass0 = p0->klass_is_exact();

     ciKlass* klass1 = p1->klass();

     bool    xklass1 = p1->klass_is_exact();

     int kps = (p0->isa_klassptr()?1:0) + (p1->isa_klassptr()?1:0);

     if (klass0 && klass1 &&

         kps != 1 &&             // both or neither are klass pointers

         !klass0->is_interface() && // do not trust interfaces

         !klass1->is_interface()) {

       // See if neither subclasses the other, or if the class on top

       // is precise.  In either of these cases, the compare must fail.

       if (klass0->equals(klass1)   ||   // if types are unequal but klasses are

           !klass0->is_java_klass() ||   // types not part of Java language?

           !klass1->is_java_klass()) {   // types not part of Java language?

         // Do nothing; we know nothing for imprecise types

       } else if (klass0->is_subtype_of(klass1)) {

         // If klass1's type is PRECISE, then we can fail.

         if (xklass1)  return TypeInt::CC_GT;

       } else if (klass1->is_subtype_of(klass0)) {

         // If klass0's type is PRECISE, then we can fail.

         if (xklass0)  return TypeInt::CC_GT;

       } else {                  // Neither subtypes the other

         return TypeInt::CC_GT;  // ...so always fail

       }

     }

   }

   // Known constants can be compared exactly

   // Null can be distinguished from any NotNull pointers

   // Unknown inputs makes an unknown result

   if( r0->singleton() ) {

     intptr_t bits0 = r0->get_con();

     if( r1->singleton() )

       return bits0 == r1->get_con() ? TypeInt::CC_EQ : TypeInt::CC_GT;

     return ( r1->_ptr == TypePtr::NotNull && bits0==0 ) ? TypeInt::CC_GT : TypeInt::CC;

   } else if( r1->singleton() ) {

     intptr_t bits1 = r1->get_con();

     return ( r0->_ptr == TypePtr::NotNull && bits1==0 ) ? TypeInt::CC_GT : TypeInt::CC;

   } else

     return TypeInt::CC;

 }

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

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

   return NULL;

 }

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

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

 // Simplify an CmpF (compare 2 floats ) node, based on local information.

 // If both inputs are constants, compare them.

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

   const Node* in1 = in(1);

   const Node* in2 = in(2);

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

   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);

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

   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);

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

   // Not constants?  Don't know squat - even if they are the same

   // value!  If they are NaN's they compare to LT instead of EQ.

   const TypeF *tf1 = t1->isa_float_constant();

   const TypeF *tf2 = t2->isa_float_constant();

   if( !tf1 || !tf2 ) return TypeInt::CC;

   // This implements the Java bytecode fcmpl, so unordered returns -1.

   if( tf1->is_nan() || tf2->is_nan() )

     return TypeInt::CC_LT;

   if( tf1->_f < tf2->_f ) return TypeInt::CC_LT;

   if( tf1->_f > tf2->_f ) return TypeInt::CC_GT;

   assert( tf1->_f == tf2->_f, "do not understand FP behavior" );

   return TypeInt::CC_EQ;

 }

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

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

 // Simplify an CmpD (compare 2 doubles ) node, based on local information.

 // If both inputs are constants, compare them.

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

   const Node* in1 = in(1);

   const Node* in2 = in(2);

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

   const Type* t1 = (in1 == this) ? Type::TOP : phase->type(in1);

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

   const Type* t2 = (in2 == this) ? Type::TOP : phase->type(in2);

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

   // Not constants?  Don't know squat - even if they are the same

   // value!  If they are NaN's they compare to LT instead of EQ.

   const TypeD *td1 = t1->isa_double_constant();

   const TypeD *td2 = t2->isa_double_constant();

   if( !td1 || !td2 ) return TypeInt::CC;

   // This implements the Java bytecode dcmpl, so unordered returns -1.

   if( td1->is_nan() || td2->is_nan() )

     return TypeInt::CC_LT;

   if( td1->_d < td2->_d ) return TypeInt::CC_LT;

   if( td1->_d > td2->_d ) return TypeInt::CC_GT;

   assert( td1->_d == td2->_d, "do not understand FP behavior" );

   return TypeInt::CC_EQ;

 }

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

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

   // Check if we can change this to a CmpF and remove a ConvD2F operation.

   // Change  (CMPD (F2D (float)) (ConD value))

   // To      (CMPF      (float)  (ConF value))

   // Valid when 'value' does not lose precision as a float.

   // Benefits: eliminates conversion, does not require 24-bit mode

   // NaNs prevent commuting operands.  This transform works regardless of the

   // order of ConD and ConvF2D inputs by preserving the original order.

   int idx_f2d = 1;              // ConvF2D on left side?

   if( in(idx_f2d)->Opcode() != Op_ConvF2D )

     idx_f2d = 2;                // No, swap to check for reversed args

   int idx_con = 3-idx_f2d;      // Check for the constant on other input

   if( ConvertCmpD2CmpF &&

       in(idx_f2d)->Opcode() == Op_ConvF2D &&

       in(idx_con)->Opcode() == Op_ConD ) {

     const TypeD *t2 = in(idx_con)->bottom_type()->is_double_constant();

     double t2_value_as_double = t2->_d;

     float  t2_value_as_float  = (float)t2_value_as_double;

     if( t2_value_as_double == (double)t2_value_as_float ) {

       // Test value can be represented as a float

       // Eliminate the conversion to double and create new comparison

       Node *new_in1 = in(idx_f2d)->in(1);

       Node *new_in2 = phase->makecon( TypeF::make(t2_value_as_float) );

       if( idx_f2d != 1 ) {      // Must flip args to match original order

         Node *tmp = new_in1;

         new_in1 = new_in2;

         new_in2 = tmp;

       }

       CmpFNode *new_cmp = (Opcode() == Op_CmpD3)

         ? new (phase->C, 3) CmpF3Node( new_in1, new_in2 )

         : new (phase->C, 3) CmpFNode ( new_in1, new_in2 ) ;

       return new_cmp;           // Changed to CmpFNode

     }

     // Testing value required the precision of a double

   }

   return NULL;                  // No change

 }

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

 //------------------------------cc2logical-------------------------------------

 // Convert a condition code type to a logical type

 const Type *BoolTest::cc2logical( const Type *CC ) const {

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

   if( CC->base() != Type::Int ) return TypeInt::BOOL; // Bottom or worse

   const TypeInt *ti = CC->is_int();

   if( ti->is_con() ) {          // Only 1 kind of condition codes set?

     // Match low order 2 bits

     int tmp = ((ti->get_con()&3) == (_test&3)) ? 1 : 0;

     if( _test & 4 ) tmp = 1-tmp;     // Optionally complement result

     return TypeInt::make(tmp);       // Boolean result

   }

   if( CC == TypeInt::CC_GE ) {

     if( _test == ge ) return TypeInt::ONE;

     if( _test == lt ) return TypeInt::ZERO;

   }

   if( CC == TypeInt::CC_LE ) {

     if( _test == le ) return TypeInt::ONE;

     if( _test == gt ) return TypeInt::ZERO;

   }

   return TypeInt::BOOL;

 }

 //------------------------------dump_spec-------------------------------------

 // Print special per-node info

 #ifndef PRODUCT

 void BoolTest::dump_on(outputStream *st) const {

   const char *msg[] = {"eq","gt","??","lt","ne","le","??","ge"};

   st->print(msg[_test]);

 }

 #endif

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

 uint BoolNode::hash() const { return (Node::hash() << 3)|(_test._test+1); }

 uint BoolNode::size_of() const { return sizeof(BoolNode); }

 //------------------------------operator==-------------------------------------

 uint BoolNode::cmp( const Node &n ) const {

   const BoolNode *b = (const BoolNode *)&n; // Cast up

   return (_test._test == b->_test._test);

 }

 //------------------------------clone_cmp--------------------------------------

 // Clone a compare/bool tree

 static Node *clone_cmp( Node *cmp, Node *cmp1, Node *cmp2, PhaseGVN *gvn, BoolTest::mask test ) {

   Node *ncmp = cmp->clone();

   ncmp->set_req(1,cmp1);

   ncmp->set_req(2,cmp2);

   ncmp = gvn->transform( ncmp );

   return new (gvn->C, 2) BoolNode( ncmp, test );

 }

 //-------------------------------make_predicate--------------------------------

 Node* BoolNode::make_predicate(Node* test_value, PhaseGVN* phase) {

   if (test_value->is_Con())   return test_value;

   if (test_value->is_Bool())  return test_value;

   Compile* C = phase->C;

   if (test_value->is_CMove() &&

       test_value->in(CMoveNode::Condition)->is_Bool()) {

     BoolNode*   bol   = test_value->in(CMoveNode::Condition)->as_Bool();

     const Type* ftype = phase->type(test_value->in(CMoveNode::IfFalse));

     const Type* ttype = phase->type(test_value->in(CMoveNode::IfTrue));

     if (ftype == TypeInt::ZERO && !TypeInt::ZERO->higher_equal(ttype)) {

       return bol;

     } else if (ttype == TypeInt::ZERO && !TypeInt::ZERO->higher_equal(ftype)) {

       return phase->transform( bol->negate(phase) );

     }

     // Else fall through.  The CMove gets in the way of the test.

     // It should be the case that make_predicate(bol->as_int_value()) == bol.

   }

   Node* cmp = new (C, 3) CmpINode(test_value, phase->intcon(0));

   cmp = phase->transform(cmp);

   Node* bol = new (C, 2) BoolNode(cmp, BoolTest::ne);

   return phase->transform(bol);

 }

 //--------------------------------as_int_value---------------------------------

 Node* BoolNode::as_int_value(PhaseGVN* phase) {

   // Inverse to make_predicate.  The CMove probably boils down to a Conv2B.

   Node* cmov = CMoveNode::make(phase->C, NULL, this,

                                phase->intcon(0), phase->intcon(1),

                                TypeInt::BOOL);

   return phase->transform(cmov);

 }

 //----------------------------------negate-------------------------------------

 BoolNode* BoolNode::negate(PhaseGVN* phase) {

   Compile* C = phase->C;

   return new (C, 2) BoolNode(in(1), _test.negate());

 }

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

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

   // Change "bool tst (cmp con x)" into "bool ~tst (cmp x con)".

   // This moves the constant to the right.  Helps value-numbering.

   Node *cmp = in(1);

   if( !cmp->is_Sub() ) return NULL;

   int cop = cmp->Opcode();

   if( cop == Op_FastLock || cop == Op_FastUnlock ) return NULL;

   Node *cmp1 = cmp->in(1);

   Node *cmp2 = cmp->in(2);

   if( !cmp1 ) return NULL;

   // Constant on left?

   Node *con = cmp1;

   uint op2 = cmp2->Opcode();

   // Move constants to the right of compare's to canonicalize.

   // Do not muck with Opaque1 nodes, as this indicates a loop

   // guard that cannot change shape.

   if( con->is_Con() && !cmp2->is_Con() && op2 != Op_Opaque1 &&

       // Because of NaN's, CmpD and CmpF are not commutative

       cop != Op_CmpD && cop != Op_CmpF &&

       // Protect against swapping inputs to a compare when it is used by a

       // counted loop exit, which requires maintaining the loop-limit as in(2)

       !is_counted_loop_exit_test() ) {

     // Ok, commute the constant to the right of the cmp node.

     // Clone the Node, getting a new Node of the same class

     cmp = cmp->clone();

     // Swap inputs to the clone

     cmp->swap_edges(1, 2);

     cmp = phase->transform( cmp );

     return new (phase->C, 2) BoolNode( cmp, _test.commute() );

   }

   // Change "bool eq/ne (cmp (xor X 1) 0)" into "bool ne/eq (cmp X 0)".

   // The XOR-1 is an idiom used to flip the sense of a bool.  We flip the

   // test instead.

   int cmp1_op = cmp1->Opcode();

   const TypeInt* cmp2_type = phase->type(cmp2)->isa_int();

   if (cmp2_type == NULL)  return NULL;

   Node* j_xor = cmp1;

   if( cmp2_type == TypeInt::ZERO &&

       cmp1_op == Op_XorI &&

       j_xor->in(1) != j_xor &&          // An xor of itself is dead

       phase->type( j_xor->in(2) ) == TypeInt::ONE &&

       (_test._test == BoolTest::eq ||

        _test._test == BoolTest::ne) ) {

     Node *ncmp = phase->transform(new (phase->C, 3) CmpINode(j_xor->in(1),cmp2));

     return new (phase->C, 2) BoolNode( ncmp, _test.negate() );

   }

   // Change "bool eq/ne (cmp (Conv2B X) 0)" into "bool eq/ne (cmp X 0)".

   // This is a standard idiom for branching on a boolean value.

   Node *c2b = cmp1;

   if( cmp2_type == TypeInt::ZERO &&

       cmp1_op == Op_Conv2B &&

       (_test._test == BoolTest::eq ||

        _test._test == BoolTest::ne) ) {

     Node *ncmp = phase->transform(phase->type(c2b->in(1))->isa_int()

        ? (Node*)new (phase->C, 3) CmpINode(c2b->in(1),cmp2)

        : (Node*)new (phase->C, 3) CmpPNode(c2b->in(1),phase->makecon(TypePtr::NULL_PTR))

     );

     return new (phase->C, 2) BoolNode( ncmp, _test._test );

   }

   // Comparing a SubI against a zero is equal to comparing the SubI

   // arguments directly.  This only works for eq and ne comparisons

   // due to possible integer overflow.

   if ((_test._test == BoolTest::eq || _test._test == BoolTest::ne) &&

         (cop == Op_CmpI) &&

         (cmp1->Opcode() == Op_SubI) &&

         ( cmp2_type == TypeInt::ZERO ) ) {

     Node *ncmp = phase->transform( new (phase->C, 3) CmpINode(cmp1->in(1),cmp1->in(2)));

     return new (phase->C, 2) BoolNode( ncmp, _test._test );

   }

   // Change (-A vs 0) into (A vs 0) by commuting the test.  Disallow in the

   // most general case because negating 0x80000000 does nothing.  Needed for

   // the CmpF3/SubI/CmpI idiom.

   if( cop == Op_CmpI &&

       cmp1->Opcode() == Op_SubI &&

       cmp2_type == TypeInt::ZERO &&

       phase->type( cmp1->in(1) ) == TypeInt::ZERO &&

       phase->type( cmp1->in(2) )->higher_equal(TypeInt::SYMINT) ) {

     Node *ncmp = phase->transform( new (phase->C, 3) CmpINode(cmp1->in(2),cmp2));

     return new (phase->C, 2) BoolNode( ncmp, _test.commute() );

   }

   //  The transformation below is not valid for either signed or unsigned

   //  comparisons due to wraparound concerns at MAX_VALUE and MIN_VALUE.

   //  This transformation can be resurrected when we are able to

   //  make inferences about the range of values being subtracted from

   //  (or added to) relative to the wraparound point.

   //

   //    // Remove +/-1's if possible.

   //    // "X <= Y-1" becomes "X <  Y"

   //    // "X+1 <= Y" becomes "X <  Y"

   //    // "X <  Y+1" becomes "X <= Y"

   //    // "X-1 <  Y" becomes "X <= Y"

   //    // Do not this to compares off of the counted-loop-end.  These guys are

   //    // checking the trip counter and they want to use the post-incremented

   //    // counter.  If they use the PRE-incremented counter, then the counter has

   //    // to be incremented in a private block on a loop backedge.

   //    if( du && du->cnt(this) && du->out(this)[0]->Opcode() == Op_CountedLoopEnd )

   //      return NULL;

   //  #ifndef PRODUCT

   //    // Do not do this in a wash GVN pass during verification.

   //    // Gets triggered by too many simple optimizations to be bothered with

   //    // re-trying it again and again.

   //    if( !phase->allow_progress() ) return NULL;

   //  #endif

   //    // Not valid for unsigned compare because of corner cases in involving zero.

   //    // For example, replacing "X-1 <u Y" with "X <=u Y" fails to throw an

   //    // exception in case X is 0 (because 0-1 turns into 4billion unsigned but

   //    // "0 <=u Y" is always true).

   //    if( cmp->Opcode() == Op_CmpU ) return NULL;

   //    int cmp2_op = cmp2->Opcode();

   //    if( _test._test == BoolTest::le ) {

   //      if( cmp1_op == Op_AddI &&

   //          phase->type( cmp1->in(2) ) == TypeInt::ONE )

   //        return clone_cmp( cmp, cmp1->in(1), cmp2, phase, BoolTest::lt );

   //      else if( cmp2_op == Op_AddI &&

   //         phase->type( cmp2->in(2) ) == TypeInt::MINUS_1 )

   //        return clone_cmp( cmp, cmp1, cmp2->in(1), phase, BoolTest::lt );

   //    } else if( _test._test == BoolTest::lt ) {

   //      if( cmp1_op == Op_AddI &&

   //          phase->type( cmp1->in(2) ) == TypeInt::MINUS_1 )

   //        return clone_cmp( cmp, cmp1->in(1), cmp2, phase, BoolTest::le );

   //      else if( cmp2_op == Op_AddI &&

   //         phase->type( cmp2->in(2) ) == TypeInt::ONE )

   //        return clone_cmp( cmp, cmp1, cmp2->in(1), phase, BoolTest::le );

   //    }

   return NULL;

 }

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

 // Simplify a Bool (convert condition codes to boolean (1 or 0)) node,

 // based on local information.   If the input is constant, do it.

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

   return _test.cc2logical( phase->type( in(1) ) );

 }

 //------------------------------dump_spec--------------------------------------

 // Dump special per-node info

 #ifndef PRODUCT

 void BoolNode::dump_spec(outputStream *st) const {

   st->print("[");

   _test.dump_on(st);

   st->print("]");

 }

 #endif

 //------------------------------is_counted_loop_exit_test--------------------------------------

 // Returns true if node is used by a counted loop node.

 bool BoolNode::is_counted_loop_exit_test() {

   for( DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++ ) {

     Node* use = fast_out(i);

     if (use->is_CountedLoopEnd()) {

       return true;

     }

   }

   return false;

 }

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

 //------------------------------NegNode----------------------------------------

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

   if( in(1)->Opcode() == Op_SubF )

     return new (phase->C, 3) SubFNode( in(1)->in(2), in(1)->in(1) );

   return NULL;

 }

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

   if( in(1)->Opcode() == Op_SubD )

     return new (phase->C, 3) SubDNode( in(1)->in(2), in(1)->in(1) );

   return NULL;

 }

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

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

 // Compute sqrt

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

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

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

   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;

   double d = t1->getd();

   if( d < 0.0 ) return Type::DOUBLE;

   return TypeD::make( sqrt( d ) );

 }

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

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

 // Compute cos

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

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

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

   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;

   double d = t1->getd();

   if( d < 0.0 ) return Type::DOUBLE;

   return TypeD::make( SharedRuntime::dcos( d ) );

 }

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

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

 // Compute sin

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

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

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

   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;

   double d = t1->getd();

   if( d < 0.0 ) return Type::DOUBLE;

   return TypeD::make( SharedRuntime::dsin( d ) );

 }

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

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

 // Compute tan

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

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

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

   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;

   double d = t1->getd();

   if( d < 0.0 ) return Type::DOUBLE;

   return TypeD::make( SharedRuntime::dtan( d ) );

 }

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

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

 // Compute log

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

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

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

   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;

   double d = t1->getd();

   if( d < 0.0 ) return Type::DOUBLE;

   return TypeD::make( SharedRuntime::dlog( d ) );

 }

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

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

 // Compute log10

 const Type *Log10DNode::Value( PhaseTransform *phase ) const {

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

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

   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;

   double d = t1->getd();

   if( d < 0.0 ) return Type::DOUBLE;

   return TypeD::make( SharedRuntime::dlog10( d ) );

 }

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

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

 // Compute exp

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

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

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

   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;

   double d = t1->getd();

   if( d < 0.0 ) return Type::DOUBLE;

   return TypeD::make( SharedRuntime::dexp( d ) );

 }

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

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

 // Compute pow

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

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

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

   if( t1->base() != Type::DoubleCon ) return Type::DOUBLE;

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

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

   if( t2->base() != Type::DoubleCon ) return Type::DOUBLE;

   double d1 = t1->getd();

   double d2 = t2->getd();

   if( d1 < 0.0 ) return Type::DOUBLE;

   if( d2 < 0.0 ) return Type::DOUBLE;

   return TypeD::make( SharedRuntime::dpow( d1, d2 ) );

 }