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

 /*

  * Copyright 1997-2006 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

  * have any questions.

  *

  */

 #include "incls/_precompiled.incl"

 #include "incls/_node.cpp.incl"

 class RegMask;

 // #include "phase.hpp"

 class PhaseTransform;

 class PhaseGVN;

 // Arena we are currently building Nodes in

 const uint Node::NotAMachineReg = 0xffff0000;

 #ifndef PRODUCT

 extern int nodes_created;

 #endif

 #ifdef ASSERT

 //-------------------------- construct_node------------------------------------

 // Set a breakpoint here to identify where a particular node index is built.

 void Node::verify_construction() {

   _debug_orig = NULL;

   int old_debug_idx = Compile::debug_idx();

   int new_debug_idx = old_debug_idx+1;

   if (new_debug_idx > 0) {

     // Arrange that the lowest five decimal digits of _debug_idx

     // will repeat thos of _idx.  In case this is somehow pathological,

     // we continue to assign negative numbers (!) consecutively.

     const int mod = 100000;

     int bump = (int)(_idx - new_debug_idx) % mod;

     if (bump < 0)  bump += mod;

     assert(bump >= 0 && bump < mod, "");

     new_debug_idx += bump;

   }

   Compile::set_debug_idx(new_debug_idx);

   set_debug_idx( new_debug_idx );

   assert(Compile::current()->unique() < (uint)MaxNodeLimit, "Node limit exceeded");

   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (int)_idx == BreakAtNode)) {

     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d", _idx, _debug_idx);

     BREAKPOINT;

   }

 #if OPTO_DU_ITERATOR_ASSERT

   _last_del = NULL;

   _del_tick = 0;

 #endif

   _hash_lock = 0;

 }

 // #ifdef ASSERT ...

 #if OPTO_DU_ITERATOR_ASSERT

 void DUIterator_Common::sample(const Node* node) {

   _vdui     = VerifyDUIterators;

   _node     = node;

   _outcnt   = node->_outcnt;

   _del_tick = node->_del_tick;

   _last     = NULL;

 }

 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {

   assert(_node     == node, "consistent iterator source");

   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");

 }

 void DUIterator_Common::verify_resync() {

   // Ensure that the loop body has just deleted the last guy produced.

   const Node* node = _node;

   // Ensure that at least one copy of the last-seen edge was deleted.

   // Note:  It is OK to delete multiple copies of the last-seen edge.

   // Unfortunately, we have no way to verify that all the deletions delete

   // that same edge.  On this point we must use the Honor System.

   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");

   assert(node->_last_del == _last, "must have deleted the edge just produced");

   // We liked this deletion, so accept the resulting outcnt and tick.

   _outcnt   = node->_outcnt;

   _del_tick = node->_del_tick;

 }

 void DUIterator_Common::reset(const DUIterator_Common& that) {

   if (this == &that)  return;  // ignore assignment to self

   if (!_vdui) {

     // We need to initialize everything, overwriting garbage values.

     _last = that._last;

     _vdui = that._vdui;

   }

   // Note:  It is legal (though odd) for an iterator over some node x

   // to be reassigned to iterate over another node y.  Some doubly-nested

   // progress loops depend on being able to do this.

   const Node* node = that._node;

   // Re-initialize everything, except _last.

   _node     = node;

   _outcnt   = node->_outcnt;

   _del_tick = node->_del_tick;

 }

 void DUIterator::sample(const Node* node) {

   DUIterator_Common::sample(node);      // Initialize the assertion data.

   _refresh_tick = 0;                    // No refreshes have happened, as yet.

 }

 void DUIterator::verify(const Node* node, bool at_end_ok) {

   DUIterator_Common::verify(node, at_end_ok);

   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");

 }

 void DUIterator::verify_increment() {

   if (_refresh_tick & 1) {

     // We have refreshed the index during this loop.

     // Fix up _idx to meet asserts.

     if (_idx > _outcnt)  _idx = _outcnt;

   }

   verify(_node, true);

 }

 void DUIterator::verify_resync() {

   // Note:  We do not assert on _outcnt, because insertions are OK here.

   DUIterator_Common::verify_resync();

   // Make sure we are still in sync, possibly with no more out-edges:

   verify(_node, true);

 }

 void DUIterator::reset(const DUIterator& that) {

   if (this == &that)  return;  // self assignment is always a no-op

   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");

   assert(that._idx          == 0, "assign only the result of Node::outs()");

   assert(_idx               == that._idx, "already assigned _idx");

   if (!_vdui) {

     // We need to initialize everything, overwriting garbage values.

     sample(that._node);

   } else {

     DUIterator_Common::reset(that);

     if (_refresh_tick & 1) {

       _refresh_tick++;                  // Clear the "was refreshed" flag.

     }

     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");

   }

 }

 void DUIterator::refresh() {

   DUIterator_Common::sample(_node);     // Re-fetch assertion data.

   _refresh_tick |= 1;                   // Set the "was refreshed" flag.

 }

 void DUIterator::verify_finish() {

   // If the loop has killed the node, do not require it to re-run.

   if (_node->_outcnt == 0)  _refresh_tick &= ~1;

   // If this assert triggers, it means that a loop used refresh_out_pos

   // to re-synch an iteration index, but the loop did not correctly

   // re-run itself, using a "while (progress)" construct.

   // This iterator enforces the rule that you must keep trying the loop

   // until it "runs clean" without any need for refreshing.

   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");

 }

 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {

   DUIterator_Common::verify(node, at_end_ok);

   Node** out    = node->_out;

   uint   cnt    = node->_outcnt;

   assert(cnt == _outcnt, "no insertions allowed");

   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");

   // This last check is carefully designed to work for NO_OUT_ARRAY.

 }

 void DUIterator_Fast::verify_limit() {

   const Node* node = _node;

   verify(node, true);

   assert(_outp == node->_out + node->_outcnt, "limit still correct");

 }

 void DUIterator_Fast::verify_resync() {

   const Node* node = _node;

   if (_outp == node->_out + _outcnt) {

     // Note that the limit imax, not the pointer i, gets updated with the

     // exact count of deletions.  (For the pointer it's always "--i".)

     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");

     // This is a limit pointer, with a name like "imax".

     // Fudge the _last field so that the common assert will be happy.

     _last = (Node*) node->_last_del;

     DUIterator_Common::verify_resync();

   } else {

     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");

     // A normal internal pointer.

     DUIterator_Common::verify_resync();

     // Make sure we are still in sync, possibly with no more out-edges:

     verify(node, true);

   }

 }

 void DUIterator_Fast::verify_relimit(uint n) {

   const Node* node = _node;

   assert((int)n > 0, "use imax -= n only with a positive count");

   // This must be a limit pointer, with a name like "imax".

   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");

   // The reported number of deletions must match what the node saw.

   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");

   // Fudge the _last field so that the common assert will be happy.

   _last = (Node*) node->_last_del;

   DUIterator_Common::verify_resync();

 }

 void DUIterator_Fast::reset(const DUIterator_Fast& that) {

   assert(_outp              == that._outp, "already assigned _outp");

   DUIterator_Common::reset(that);

 }

 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {

   // at_end_ok means the _outp is allowed to underflow by 1

   _outp += at_end_ok;

   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.

   _outp -= at_end_ok;

   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");

 }

 void DUIterator_Last::verify_limit() {

   // Do not require the limit address to be resynched.

   //verify(node, true);

   assert(_outp == _node->_out, "limit still correct");

 }

 void DUIterator_Last::verify_step(uint num_edges) {

   assert((int)num_edges > 0, "need non-zero edge count for loop progress");

   _outcnt   -= num_edges;

   _del_tick += num_edges;

   // Make sure we are still in sync, possibly with no more out-edges:

   const Node* node = _node;

   verify(node, true);

   assert(node->_last_del == _last, "must have deleted the edge just produced");

 }

 #endif //OPTO_DU_ITERATOR_ASSERT

 #endif //ASSERT

 // This constant used to initialize _out may be any non-null value.

 // The value NULL is reserved for the top node only.

 #define NO_OUT_ARRAY ((Node**)-1)

 // This funny expression handshakes with Node::operator new

 // to pull Compile::current out of the new node's _out field,

 // and then calls a subroutine which manages most field

 // initializations.  The only one which is tricky is the

 // _idx field, which is const, and so must be initialized

 // by a return value, not an assignment.

 //

 // (Aren't you thankful that Java finals don't require so many tricks?)

 #define IDX_INIT(req) this->Init((req), (Compile*) this->_out)

 #ifdef _MSC_VER // the IDX_INIT hack falls foul of warning C4355

 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list

 #endif

 // Out-of-line code from node constructors.

 // Executed only when extra debug info. is being passed around.

 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {

   C->set_node_notes_at(idx, nn);

 }

 // Shared initialization code.

 inline int Node::Init(int req, Compile* C) {

   assert(Compile::current() == C, "must use operator new(Compile*)");

   int idx = C->next_unique();

   // If there are default notes floating around, capture them:

   Node_Notes* nn = C->default_node_notes();

   if (nn != NULL)  init_node_notes(C, idx, nn);

   // Note:  At this point, C is dead,

   // and we begin to initialize the new Node.

   _cnt = _max = req;

   _outcnt = _outmax = 0;

   _class_id = Class_Node;

   _flags = 0;

   _out = NO_OUT_ARRAY;

   return idx;

 }

 //------------------------------Node-------------------------------------------

 // Create a Node, with a given number of required edges.

 Node::Node(uint req)

   : _idx(IDX_INIT(req))

 {

   assert( req < (uint)(MaxNodeLimit - NodeLimitFudgeFactor), "Input limit exceeded" );

   debug_only( verify_construction() );

   NOT_PRODUCT(nodes_created++);

   if (req == 0) {

     assert( _in == (Node**)this, "Must not pass arg count to 'new'" );

     _in = NULL;

   } else {

     assert( _in[req-1] == this, "Must pass arg count to 'new'" );

     Node** to = _in;

     for(uint i = 0; i < req; i++) {

       to[i] = NULL;

     }

   }

 }

 //------------------------------Node-------------------------------------------

 Node::Node(Node *n0)

   : _idx(IDX_INIT(1))

 {

   debug_only( verify_construction() );

   NOT_PRODUCT(nodes_created++);

   // Assert we allocated space for input array already

   assert( _in[0] == this, "Must pass arg count to 'new'" );

   assert( is_not_dead(n0), "can not use dead node");

   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);

 }

 //------------------------------Node-------------------------------------------

 Node::Node(Node *n0, Node *n1)

   : _idx(IDX_INIT(2))

 {

   debug_only( verify_construction() );

   NOT_PRODUCT(nodes_created++);

   // Assert we allocated space for input array already

   assert( _in[1] == this, "Must pass arg count to 'new'" );

   assert( is_not_dead(n0), "can not use dead node");

   assert( is_not_dead(n1), "can not use dead node");

   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);

   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);

 }

 //------------------------------Node-------------------------------------------

 Node::Node(Node *n0, Node *n1, Node *n2)

   : _idx(IDX_INIT(3))

 {

   debug_only( verify_construction() );

   NOT_PRODUCT(nodes_created++);

   // Assert we allocated space for input array already

   assert( _in[2] == this, "Must pass arg count to 'new'" );

   assert( is_not_dead(n0), "can not use dead node");

   assert( is_not_dead(n1), "can not use dead node");

   assert( is_not_dead(n2), "can not use dead node");

   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);

   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);

   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);

 }

 //------------------------------Node-------------------------------------------

 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)

   : _idx(IDX_INIT(4))

 {

   debug_only( verify_construction() );

   NOT_PRODUCT(nodes_created++);

   // Assert we allocated space for input array already

   assert( _in[3] == this, "Must pass arg count to 'new'" );

   assert( is_not_dead(n0), "can not use dead node");

   assert( is_not_dead(n1), "can not use dead node");

   assert( is_not_dead(n2), "can not use dead node");

   assert( is_not_dead(n3), "can not use dead node");

   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);

   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);

   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);

   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);

 }

 //------------------------------Node-------------------------------------------

 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)

   : _idx(IDX_INIT(5))

 {

   debug_only( verify_construction() );

   NOT_PRODUCT(nodes_created++);

   // Assert we allocated space for input array already

   assert( _in[4] == this, "Must pass arg count to 'new'" );

   assert( is_not_dead(n0), "can not use dead node");

   assert( is_not_dead(n1), "can not use dead node");

   assert( is_not_dead(n2), "can not use dead node");

   assert( is_not_dead(n3), "can not use dead node");

   assert( is_not_dead(n4), "can not use dead node");

   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);

   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);

   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);

   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);

   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);

 }

 //------------------------------Node-------------------------------------------

 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,

                      Node *n4, Node *n5)

   : _idx(IDX_INIT(6))

 {

   debug_only( verify_construction() );

   NOT_PRODUCT(nodes_created++);

   // Assert we allocated space for input array already

   assert( _in[5] == this, "Must pass arg count to 'new'" );

   assert( is_not_dead(n0), "can not use dead node");

   assert( is_not_dead(n1), "can not use dead node");

   assert( is_not_dead(n2), "can not use dead node");

   assert( is_not_dead(n3), "can not use dead node");

   assert( is_not_dead(n4), "can not use dead node");

   assert( is_not_dead(n5), "can not use dead node");

   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);

   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);

   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);

   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);

   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);

   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);

 }

 //------------------------------Node-------------------------------------------

 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,

                      Node *n4, Node *n5, Node *n6)

   : _idx(IDX_INIT(7))

 {

   debug_only( verify_construction() );

   NOT_PRODUCT(nodes_created++);

   // Assert we allocated space for input array already

   assert( _in[6] == this, "Must pass arg count to 'new'" );

   assert( is_not_dead(n0), "can not use dead node");

   assert( is_not_dead(n1), "can not use dead node");

   assert( is_not_dead(n2), "can not use dead node");

   assert( is_not_dead(n3), "can not use dead node");

   assert( is_not_dead(n4), "can not use dead node");

   assert( is_not_dead(n5), "can not use dead node");

   assert( is_not_dead(n6), "can not use dead node");

   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);

   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);

   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);

   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);

   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);

   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);

   _in[6] = n6; if (n6 != NULL) n6->add_out((Node *)this);

 }

 //------------------------------clone------------------------------------------

 // Clone a Node.

 Node *Node::clone() const {

   Compile *compile = Compile::current();

   uint s = size_of();           // Size of inherited Node

   Node *n = (Node*)compile->node_arena()->Amalloc_D(size_of() + _max*sizeof(Node*));

   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);

   // Set the new input pointer array

   n->_in = (Node**)(((char*)n)+s);

   // Cannot share the old output pointer array, so kill it

   n->_out = NO_OUT_ARRAY;

   // And reset the counters to 0

   n->_outcnt = 0;

   n->_outmax = 0;

   // Unlock this guy, since he is not in any hash table.

   debug_only(n->_hash_lock = 0);

   // Walk the old node's input list to duplicate its edges

   uint i;

   for( i = 0; i < len(); i++ ) {

     Node *x = in(i);

     n->_in[i] = x;

     if (x != NULL) x->add_out(n);

   }

   if (is_macro())

     compile->add_macro_node(n);

   n->set_idx(compile->next_unique()); // Get new unique index as well

   debug_only( n->verify_construction() );

   NOT_PRODUCT(nodes_created++);

   // Do not patch over the debug_idx of a clone, because it makes it

   // impossible to break on the clone's moment of creation.

   //debug_only( n->set_debug_idx( debug_idx() ) );

   compile->copy_node_notes_to(n, (Node*) this);

   // MachNode clone

   uint nopnds;

   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {

     MachNode *mach  = n->as_Mach();

     MachNode *mthis = this->as_Mach();

     // Get address of _opnd_array.

     // It should be the same offset since it is the clone of this node.

     MachOper **from = mthis->_opnds;

     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +

                     pointer_delta((const void*)from,

                                   (const void*)(&mthis->_opnds), 1));

     mach->_opnds = to;

     for ( uint i = 0; i < nopnds; ++i ) {

       to[i] = from[i]->clone(compile);

     }

   }

   // cloning CallNode may need to clone JVMState

   if (n->is_Call()) {

     CallNode *call = n->as_Call();

     call->clone_jvms();

   }

   return n;                     // Return the clone

 }

 //---------------------------setup_is_top--------------------------------------

 // Call this when changing the top node, to reassert the invariants

 // required by Node::is_top.  See Compile::set_cached_top_node.

 void Node::setup_is_top() {

   if (this == (Node*)Compile::current()->top()) {

     // This node has just become top.  Kill its out array.

     _outcnt = _outmax = 0;

     _out = NULL;                           // marker value for top

     assert(is_top(), "must be top");

   } else {

     if (_out == NULL)  _out = NO_OUT_ARRAY;

     assert(!is_top(), "must not be top");

   }

 }

 //------------------------------~Node------------------------------------------

 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage

 extern int reclaim_idx ;

 extern int reclaim_in  ;

 extern int reclaim_node;

 void Node::destruct() {

   // Eagerly reclaim unique Node numberings

   Compile* compile = Compile::current();

   if ((uint)_idx+1 == compile->unique()) {

     compile->set_unique(compile->unique()-1);

 #ifdef ASSERT

     reclaim_idx++;

 #endif

   }

   // Clear debug info:

   Node_Notes* nn = compile->node_notes_at(_idx);

   if (nn != NULL)  nn->clear();

   // Walk the input array, freeing the corresponding output edges

   _cnt = _max;  // forget req/prec distinction

   uint i;

   for( i = 0; i < _max; i++ ) {

     set_req(i, NULL);

     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");

   }

   assert(outcnt() == 0, "deleting a node must not leave a dangling use");

   // See if the input array was allocated just prior to the object

   int edge_size = _max*sizeof(void*);

   int out_edge_size = _outmax*sizeof(void*);

   char *edge_end = ((char*)_in) + edge_size;

   char *out_array = (char*)(_out == NO_OUT_ARRAY? NULL: _out);

   char *out_edge_end = out_array + out_edge_size;

   int node_size = size_of();

   // Free the output edge array

   if (out_edge_size > 0) {

 #ifdef ASSERT

     if( out_edge_end == compile->node_arena()->hwm() )

       reclaim_in  += out_edge_size;  // count reclaimed out edges with in edges

 #endif

     compile->node_arena()->Afree(out_array, out_edge_size);

   }

   // Free the input edge array and the node itself

   if( edge_end == (char*)this ) {

 #ifdef ASSERT

     if( edge_end+node_size == compile->node_arena()->hwm() ) {

       reclaim_in  += edge_size;

       reclaim_node+= node_size;

     }

 #else

     // It was; free the input array and object all in one hit

     compile->node_arena()->Afree(_in,edge_size+node_size);

 #endif

   } else {

     // Free just the input array

 #ifdef ASSERT

     if( edge_end == compile->node_arena()->hwm() )

       reclaim_in  += edge_size;

 #endif

     compile->node_arena()->Afree(_in,edge_size);

     // Free just the object

 #ifdef ASSERT

     if( ((char*)this) + node_size == compile->node_arena()->hwm() )

       reclaim_node+= node_size;

 #else

     compile->node_arena()->Afree(this,node_size);

 #endif

   }

   if (is_macro()) {

     compile->remove_macro_node(this);

   }

 #ifdef ASSERT

   // We will not actually delete the storage, but we'll make the node unusable.

   *(address*)this = badAddress;  // smash the C++ vtbl, probably

   _in = _out = (Node**) badAddress;

   _max = _cnt = _outmax = _outcnt = 0;

 #endif

 }

 //------------------------------grow-------------------------------------------

 // Grow the input array, making space for more edges

 void Node::grow( uint len ) {

   Arena* arena = Compile::current()->node_arena();

   uint new_max = _max;

   if( new_max == 0 ) {

     _max = 4;

     _in = (Node**)arena->Amalloc(4*sizeof(Node*));

     Node** to = _in;

     to[0] = NULL;

     to[1] = NULL;

     to[2] = NULL;

     to[3] = NULL;

     return;

   }

   while( new_max <= len ) new_max <<= 1; // Find next power-of-2

   // Trimming to limit allows a uint8 to handle up to 255 edges.

   // Previously I was using only powers-of-2 which peaked at 128 edges.

   //if( new_max >= limit ) new_max = limit-1;

   _in = (Node**)arena->Arealloc(_in, _max*sizeof(Node*), new_max*sizeof(Node*));

   Copy::zero_to_bytes(&_in[_max], (new_max-_max)*sizeof(Node*)); // NULL all new space

   _max = new_max;               // Record new max length

   // This assertion makes sure that Node::_max is wide enough to

   // represent the numerical value of new_max.

   assert(_max == new_max && _max > len, "int width of _max is too small");

 }

 //-----------------------------out_grow----------------------------------------

 // Grow the input array, making space for more edges

 void Node::out_grow( uint len ) {

   assert(!is_top(), "cannot grow a top node's out array");

   Arena* arena = Compile::current()->node_arena();

   uint new_max = _outmax;

   if( new_max == 0 ) {

     _outmax = 4;

     _out = (Node **)arena->Amalloc(4*sizeof(Node*));

     return;

   }

   while( new_max <= len ) new_max <<= 1; // Find next power-of-2

   // Trimming to limit allows a uint8 to handle up to 255 edges.

   // Previously I was using only powers-of-2 which peaked at 128 edges.

   //if( new_max >= limit ) new_max = limit-1;

   assert(_out != NULL && _out != NO_OUT_ARRAY, "out must have sensible value");

   _out = (Node**)arena->Arealloc(_out,_outmax*sizeof(Node*),new_max*sizeof(Node*));

   //Copy::zero_to_bytes(&_out[_outmax], (new_max-_outmax)*sizeof(Node*)); // NULL all new space

   _outmax = new_max;               // Record new max length

   // This assertion makes sure that Node::_max is wide enough to

   // represent the numerical value of new_max.

   assert(_outmax == new_max && _outmax > len, "int width of _outmax is too small");

 }

 #ifdef ASSERT

 //------------------------------is_dead----------------------------------------

 bool Node::is_dead() const {

   // Mach and pinch point nodes may look like dead.

   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )

     return false;

   for( uint i = 0; i < _max; i++ )

     if( _in[i] != NULL )

       return false;

   dump();

   return true;

 }

 #endif

 //------------------------------add_req----------------------------------------

 // Add a new required input at the end

 void Node::add_req( Node *n ) {

   assert( is_not_dead(n), "can not use dead node");

   // Look to see if I can move precedence down one without reallocating

   if( (_cnt >= _max) || (in(_max-1) != NULL) )

     grow( _max+1 );

   // Find a precedence edge to move

   if( in(_cnt) != NULL ) {       // Next precedence edge is busy?

     uint i;

     for( i=_cnt; i<_max; i++ )

       if( in(i) == NULL )       // Find the NULL at end of prec edge list

         break;                  // There must be one, since we grew the array

     _in[i] = in(_cnt);          // Move prec over, making space for req edge

   }

   _in[_cnt++] = n;            // Stuff over old prec edge

   if (n != NULL) n->add_out((Node *)this);

 }

 //---------------------------add_req_batch-------------------------------------

 // Add a new required input at the end

 void Node::add_req_batch( Node *n, uint m ) {

   assert( is_not_dead(n), "can not use dead node");

   // check various edge cases

   if ((int)m <= 1) {

     assert((int)m >= 0, "oob");

     if (m != 0)  add_req(n);

     return;

   }

   // Look to see if I can move precedence down one without reallocating

   if( (_cnt+m) > _max || _in[_max-m] )

     grow( _max+m );

   // Find a precedence edge to move

   if( _in[_cnt] != NULL ) {     // Next precedence edge is busy?

     uint i;

     for( i=_cnt; i<_max; i++ )

       if( _in[i] == NULL )      // Find the NULL at end of prec edge list

         break;                  // There must be one, since we grew the array

     // Slide all the precs over by m positions (assume #prec << m).

     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));

   }

   // Stuff over the old prec edges

   for(uint i=0; i<m; i++ ) {

     _in[_cnt++] = n;

   }

   // Insert multiple out edges on the node.

   if (n != NULL && !n->is_top()) {

     for(uint i=0; i<m; i++ ) {

       n->add_out((Node *)this);

     }

   }

 }

 //------------------------------del_req----------------------------------------

 // Delete the required edge and compact the edge array

 void Node::del_req( uint idx ) {

   // First remove corresponding def-use edge

   Node *n = in(idx);

   if (n != NULL) n->del_out((Node *)this);

   _in[idx] = in(--_cnt);  // Compact the array

   _in[_cnt] = NULL;       // NULL out emptied slot

 }

 //------------------------------ins_req----------------------------------------

 // Insert a new required input at the end

 void Node::ins_req( uint idx, Node *n ) {

   assert( is_not_dead(n), "can not use dead node");

   add_req(NULL);                // Make space

   assert( idx < _max, "Must have allocated enough space");

   // Slide over

   if(_cnt-idx-1 > 0) {

     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));

   }

   _in[idx] = n;                            // Stuff over old required edge

   if (n != NULL) n->add_out((Node *)this); // Add reciprocal def-use edge

 }

 //-----------------------------find_edge---------------------------------------

 int Node::find_edge(Node* n) {

   for (uint i = 0; i < len(); i++) {

     if (_in[i] == n)  return i;

   }

   return -1;

 }

 //----------------------------replace_edge-------------------------------------

 int Node::replace_edge(Node* old, Node* neww) {

   if (old == neww)  return 0;  // nothing to do

   uint nrep = 0;

   for (uint i = 0; i < len(); i++) {

     if (in(i) == old) {

       if (i < req())

         set_req(i, neww);

       else

         set_prec(i, neww);

       nrep++;

     }

   }

   return nrep;

 }

 //-------------------------disconnect_inputs-----------------------------------

 // NULL out all inputs to eliminate incoming Def-Use edges.

 // Return the number of edges between 'n' and 'this'

 int Node::disconnect_inputs(Node *n) {

   int edges_to_n = 0;

   uint cnt = req();

   for( uint i = 0; i < cnt; ++i ) {

     if( in(i) == 0 ) continue;

     if( in(i) == n ) ++edges_to_n;

     set_req(i, NULL);

   }

   // Remove precedence edges if any exist

   // Note: Safepoints may have precedence edges, even during parsing

   if( (req() != len()) && (in(req()) != NULL) ) {

     uint max = len();

     for( uint i = 0; i < max; ++i ) {

       if( in(i) == 0 ) continue;

       if( in(i) == n ) ++edges_to_n;

       set_prec(i, NULL);

     }

   }

   // Node::destruct requires all out edges be deleted first

   // debug_only(destruct();)   // no reuse benefit expected

   return edges_to_n;

 }

 //-----------------------------uncast---------------------------------------

 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.

 // Strip away casting.  (It is depth-limited.)

 Node* Node::uncast() const {

   // Should be inline:

   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;

   if (is_ConstraintCast() || is_CheckCastPP())

     return uncast_helper(this);

   else

     return (Node*) this;

 }

 //---------------------------uncast_helper-------------------------------------

 Node* Node::uncast_helper(const Node* p) {

   uint max_depth = 3;

   for (uint i = 0; i < max_depth; i++) {

     if (p == NULL || p->req() != 2) {

       break;

     } else if (p->is_ConstraintCast()) {

       p = p->in(1);

     } else if (p->is_CheckCastPP()) {

       p = p->in(1);

     } else {

       break;

     }

   }

   return (Node*) p;

 }

 //------------------------------add_prec---------------------------------------

 // Add a new precedence input.  Precedence inputs are unordered, with

 // duplicates removed and NULLs packed down at the end.

 void Node::add_prec( Node *n ) {

   assert( is_not_dead(n), "can not use dead node");

   // Check for NULL at end

   if( _cnt >= _max || in(_max-1) )

     grow( _max+1 );

   // Find a precedence edge to move

   uint i = _cnt;

   while( in(i) != NULL ) i++;

   _in[i] = n;                                // Stuff prec edge over NULL

   if ( n != NULL) n->add_out((Node *)this);  // Add mirror edge

 }

 //------------------------------rm_prec----------------------------------------

 // Remove a precedence input.  Precedence inputs are unordered, with

 // duplicates removed and NULLs packed down at the end.

 void Node::rm_prec( uint j ) {

   // Find end of precedence list to pack NULLs

   uint i;

   for( i=j; i<_max; i++ )

     if( !_in[i] )               // Find the NULL at end of prec edge list

       break;

   if (_in[j] != NULL) _in[j]->del_out((Node *)this);

   _in[j] = _in[--i];            // Move last element over removed guy

   _in[i] = NULL;                // NULL out last element

 }

 //------------------------------size_of----------------------------------------

 uint Node::size_of() const { return sizeof(*this); }

 //------------------------------ideal_reg--------------------------------------

 uint Node::ideal_reg() const { return 0; }

 //------------------------------jvms-------------------------------------------

 JVMState* Node::jvms() const { return NULL; }

 #ifdef ASSERT

 //------------------------------jvms-------------------------------------------

 bool Node::verify_jvms(const JVMState* using_jvms) const {

   for (JVMState* jvms = this->jvms(); jvms != NULL; jvms = jvms->caller()) {

     if (jvms == using_jvms)  return true;

   }

   return false;

 }

 //------------------------------init_NodeProperty------------------------------

 void Node::init_NodeProperty() {

   assert(_max_classes <= max_jushort, "too many NodeProperty classes");

   assert(_max_flags <= max_jushort, "too many NodeProperty flags");

 }

 #endif

 //------------------------------format-----------------------------------------

 // Print as assembly

 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}

 //------------------------------emit-------------------------------------------

 // Emit bytes starting at parameter 'ptr'.

 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}

 //------------------------------size-------------------------------------------

 // Size of instruction in bytes

 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }

 //------------------------------CFG Construction-------------------------------

 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,

 // Goto and Return.

 const Node *Node::is_block_proj() const { return 0; }

 // Minimum guaranteed type

 const Type *Node::bottom_type() const { return Type::BOTTOM; }

 //------------------------------raise_bottom_type------------------------------

 // Get the worst-case Type output for this Node.

 void Node::raise_bottom_type(const Type* new_type) {

   if (is_Type()) {

     TypeNode *n = this->as_Type();

     if (VerifyAliases) {

       assert(new_type->higher_equal(n->type()), "new type must refine old type");

     }

     n->set_type(new_type);

   } else if (is_Load()) {

     LoadNode *n = this->as_Load();

     if (VerifyAliases) {

       assert(new_type->higher_equal(n->type()), "new type must refine old type");

     }

     n->set_type(new_type);

   }

 }

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

 // Return a node that the given node is equivalent to.

 Node *Node::Identity( PhaseTransform * ) {

   return this;                  // Default to no identities

 }

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

 // Compute a new Type for a node using the Type of the inputs.

 const Type *Node::Value( PhaseTransform * ) const {

   return bottom_type();         // Default to worst-case Type

 }

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

 //

 // 'Idealize' the graph rooted at this Node.

 //

 // In order to be efficient and flexible there are some subtle invariants

 // these Ideal calls need to hold.  Running with '+VerifyIterativeGVN' checks

 // these invariants, although its too slow to have on by default.  If you are

 // hacking an Ideal call, be sure to test with +VerifyIterativeGVN!

 //

 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'

 // pointer.  If ANY change is made, it must return the root of the reshaped

 // graph - even if the root is the same Node.  Example: swapping the inputs

 // to an AddINode gives the same answer and same root, but you still have to

 // return the 'this' pointer instead of NULL.

 //

 // You cannot return an OLD Node, except for the 'this' pointer.  Use the

 // Identity call to return an old Node; basically if Identity can find

 // another Node have the Ideal call make no change and return NULL.

 // Example: AddINode::Ideal must check for add of zero; in this case it

 // returns NULL instead of doing any graph reshaping.

 //

 // You cannot modify any old Nodes except for the 'this' pointer.  Due to

 // sharing there may be other users of the old Nodes relying on their current

 // semantics.  Modifying them will break the other users.

 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for

 // "X+3" unchanged in case it is shared.

 //

 // If you modify the 'this' pointer's inputs, you must use 'set_req' with

 // def-use info.  If you are making a new Node (either as the new root or

 // some new internal piece) you must NOT use set_req with def-use info.

 // You can make a new Node with either 'new' or 'clone'.  In either case,

 // def-use info is (correctly) not generated.

 // Example: reshape "(X+3)+4" into "X+7":

 //    set_req(1,in(1)->in(1) /* grab X */, du /* must use DU on 'this' */);

 //    set_req(2,phase->intcon(7),du);

 //    return this;

 // Example: reshape "X*4" into "X<<1"

 //    return new (C,3) LShiftINode( in(1), phase->intcon(1) );

 //

 // You must call 'phase->transform(X)' on any new Nodes X you make, except

 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-1".

 //    Node *shift=phase->transform(new(C,3)LShiftINode(in(1),phase->intcon(5)));

 //    return new (C,3) AddINode(shift, phase->intcon(-1));

 //

 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.

 // These forms are faster than 'phase->transform(new (C,1) ConNode())' and Do

 // The Right Thing with def-use info.

 //

 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped

 // graph uses the 'this' Node it must be the root.  If you want a Node with

 // the same Opcode as the 'this' pointer use 'clone'.

 //

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

   return NULL;                  // Default to being Ideal already

 }

 // Some nodes have specific Ideal subgraph transformations only if they are

 // unique users of specific nodes. Such nodes should be put on IGVN worklist

 // for the transformations to happen.

 bool Node::has_special_unique_user() const {

   assert(outcnt() == 1, "match only for unique out");

   Node* n = unique_out();

   int op  = Opcode();

   if( this->is_Store() ) {

     // Condition for back-to-back stores folding.

     return n->Opcode() == op && n->in(MemNode::Memory) == this;

   } else if( op == Op_AddL ) {

     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))

     return n->Opcode() == Op_ConvL2I && n->in(1) == this;

   } else if( op == Op_SubI || op == Op_SubL ) {

     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)

     return n->Opcode() == op && n->in(2) == this;

   }

   return false;

 };

 //------------------------------remove_dead_region-----------------------------

 // This control node is dead.  Follow the subgraph below it making everything

 // using it dead as well.  This will happen normally via the usual IterGVN

 // worklist but this call is more efficient.  Do not update use-def info

 // inside the dead region, just at the borders.

 static bool kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {

   // Con's are a popular node to re-hit in the hash table again.

   if( dead->is_Con() ) return false;

   // Can't put ResourceMark here since igvn->_worklist uses the same arena

   // for verify pass with +VerifyOpto and we add/remove elements in it here.

   Node_List  nstack(Thread::current()->resource_area());

   Node *top = igvn->C->top();

   bool progress = false;

   nstack.push(dead);

   while (nstack.size() > 0) {

     dead = nstack.pop();

     if (dead->outcnt() > 0) {

       // Keep dead node on stack until all uses are processed.

       nstack.push(dead);

       // For all Users of the Dead...    ;-)

       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {

         Node* use = dead->last_out(k);

         igvn->hash_delete(use);       // Yank from hash table prior to mod

         if (use->in(0) == dead) {     // Found another dead node

           assert (!use->is_Con(), "Control for Con node should be Root node.")

           use->set_req(0, top);       // Cut dead edge to prevent processing

           nstack.push(use);           // the dead node again.

         } else {                      // Else found a not-dead user

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

             if (use->in(j) == dead) { // Turn all dead inputs into TOP

               use->set_req(j, top);

             }

           }

           igvn->_worklist.push(use);

         }

         // Refresh the iterator, since any number of kills might have happened.

         k = dead->last_outs(kmin);

       }

     } else { // (dead->outcnt() == 0)

       // Done with outputs.

       igvn->hash_delete(dead);

       igvn->_worklist.remove(dead);

       igvn->set_type(dead, Type::TOP);

       if (dead->is_macro()) {

         igvn->C->remove_macro_node(dead);

       }

       // Kill all inputs to the dead guy

       for (uint i=0; i < dead->req(); i++) {

         Node *n = dead->in(i);      // Get input to dead guy

         if (n != NULL && !n->is_top()) { // Input is valid?

           progress = true;

           dead->set_req(i, top);    // Smash input away

           if (n->outcnt() == 0) {   // Input also goes dead?

             if (!n->is_Con())

               nstack.push(n);       // Clear it out as well

           } else if (n->outcnt() == 1 &&

                      n->has_special_unique_user()) {

             igvn->add_users_to_worklist( n );

           } else if (n->outcnt() <= 2 && n->is_Store()) {

             // Push store's uses on worklist to enable folding optimization for

             // store/store and store/load to the same address.

             // The restriction (outcnt() <= 2) is the same as in set_req_X()

             // and remove_globally_dead_node().

             igvn->add_users_to_worklist( n );

           }

         }

       }

     } // (dead->outcnt() == 0)

   }   // while (nstack.size() > 0) for outputs

   return progress;

 }

 //------------------------------remove_dead_region-----------------------------

 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {

   Node *n = in(0);

   if( !n ) return false;

   // Lost control into this guy?  I.e., it became unreachable?

   // Aggressively kill all unreachable code.

   if (can_reshape && n->is_top()) {

     return kill_dead_code(this, phase->is_IterGVN());

   }

   if( n->is_Region() && n->as_Region()->is_copy() ) {

     Node *m = n->nonnull_req();

     set_req(0, m);

     return true;

   }

   return false;

 }

 //------------------------------Ideal_DU_postCCP-------------------------------

 // Idealize graph, using DU info.  Must clone result into new-space

 Node *Node::Ideal_DU_postCCP( PhaseCCP * ) {

   return NULL;                 // Default to no change

 }

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

 // Hash function over Nodes.

 uint Node::hash() const {

   uint sum = 0;

   for( uint i=0; i<_cnt; i++ )  // Add in all inputs

     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded NULLs

   return (sum>>2) + _cnt + Opcode();

 }

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

 // Compare special parts of simple Nodes

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

   return 1;                     // Must be same

 }

 //------------------------------rematerialize-----------------------------------

 // Should we clone rather than spill this instruction?

 bool Node::rematerialize() const {

   if ( is_Mach() )

     return this->as_Mach()->rematerialize();

   else

     return (_flags & Flag_rematerialize) != 0;

 }

 //------------------------------needs_anti_dependence_check---------------------

 // Nodes which use memory without consuming it, hence need antidependences.

 bool Node::needs_anti_dependence_check() const {

   if( req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0 )

     return false;

   else

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

 }

 // Get an integer constant from a ConNode (or CastIINode).

 // Return a default value if there is no apparent constant here.

 const TypeInt* Node::find_int_type() const {

   if (this->is_Type()) {

     return this->as_Type()->type()->isa_int();

   } else if (this->is_Con()) {

     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");

     return this->bottom_type()->isa_int();

   }

   return NULL;

 }

 // Get a pointer constant from a ConstNode.

 // Returns the constant if it is a pointer ConstNode

 intptr_t Node::get_ptr() const {

   assert( Opcode() == Op_ConP, "" );

   return ((ConPNode*)this)->type()->is_ptr()->get_con();

 }

 // Get a narrow oop constant from a ConNNode.

 intptr_t Node::get_narrowcon() const {

   assert( Opcode() == Op_ConN, "" );

   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();

 }

 // Get a long constant from a ConNode.

 // Return a default value if there is no apparent constant here.

 const TypeLong* Node::find_long_type() const {

   if (this->is_Type()) {

     return this->as_Type()->type()->isa_long();

   } else if (this->is_Con()) {

     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");

     return this->bottom_type()->isa_long();

   }

   return NULL;

 }

 // Get a double constant from a ConstNode.

 // Returns the constant if it is a double ConstNode

 jdouble Node::getd() const {

   assert( Opcode() == Op_ConD, "" );

   return ((ConDNode*)this)->type()->is_double_constant()->getd();

 }

 // Get a float constant from a ConstNode.

 // Returns the constant if it is a float ConstNode

 jfloat Node::getf() const {

   assert( Opcode() == Op_ConF, "" );

   return ((ConFNode*)this)->type()->is_float_constant()->getf();

 }

 #ifndef PRODUCT

 //----------------------------NotANode----------------------------------------

 // Used in debugging code to avoid walking across dead or uninitialized edges.

 static inline bool NotANode(const Node* n) {

   if (n == NULL)                   return true;

   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.

   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct

   return false;

 }

 //------------------------------find------------------------------------------

 // Find a neighbor of this Node with the given _idx

 // If idx is negative, find its absolute value, following both _in and _out.

 static void find_recur( Node* &result, Node *n, int idx, bool only_ctrl,

                         VectorSet &old_space, VectorSet &new_space ) {

   int node_idx = (idx >= 0) ? idx : -idx;

   if (NotANode(n))  return;  // Gracefully handle NULL, -1, 0xabababab, etc.

   // Contained in new_space or old_space?

   VectorSet *v = Compile::current()->node_arena()->contains(n) ? &new_space : &old_space;

   if( v->test(n->_idx) ) return;

   if( (int)n->_idx == node_idx

       debug_only(|| n->debug_idx() == node_idx) ) {

     if (result != NULL)

       tty->print("find: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",

                  (uintptr_t)result, (uintptr_t)n, node_idx);

     result = n;

   }

   v->set(n->_idx);

   for( uint i=0; i<n->len(); i++ ) {

     if( only_ctrl && !(n->is_Region()) && (n->Opcode() != Op_Root) && (i != TypeFunc::Control) ) continue;

     find_recur( result, n->in(i), idx, only_ctrl, old_space, new_space );

   }

   // Search along forward edges also:

   if (idx < 0 && !only_ctrl) {

     for( uint j=0; j<n->outcnt(); j++ ) {

       find_recur( result, n->raw_out(j), idx, only_ctrl, old_space, new_space );

     }

   }

 #ifdef ASSERT

   // Search along debug_orig edges last:

   for (Node* orig = n->debug_orig(); orig != NULL; orig = orig->debug_orig()) {

     if (NotANode(orig))  break;

     find_recur( result, orig, idx, only_ctrl, old_space, new_space );

   }

 #endif //ASSERT

 }

 // call this from debugger:

 Node* find_node(Node* n, int idx) {

   return n->find(idx);

 }

 //------------------------------find-------------------------------------------

 Node* Node::find(int idx) const {

   ResourceArea *area = Thread::current()->resource_area();

   VectorSet old_space(area), new_space(area);

   Node* result = NULL;

   find_recur( result, (Node*) this, idx, false, old_space, new_space );

   return result;

 }

 //------------------------------find_ctrl--------------------------------------

 // Find an ancestor to this node in the control history with given _idx

 Node* Node::find_ctrl(int idx) const {

   ResourceArea *area = Thread::current()->resource_area();

   VectorSet old_space(area), new_space(area);

   Node* result = NULL;

   find_recur( result, (Node*) this, idx, true, old_space, new_space );

   return result;

 }

 #endif

 #ifndef PRODUCT

 int Node::_in_dump_cnt = 0;

 // -----------------------------Name-------------------------------------------

 extern const char *NodeClassNames[];

 const char *Node::Name() const { return NodeClassNames[Opcode()]; }

 static bool is_disconnected(const Node* n) {

   for (uint i = 0; i < n->req(); i++) {

     if (n->in(i) != NULL)  return false;

   }

   return true;

 }

 #ifdef ASSERT

 static void dump_orig(Node* orig) {

   Compile* C = Compile::current();

   if (NotANode(orig))  orig = NULL;

   if (orig != NULL && !C->node_arena()->contains(orig))  orig = NULL;

   if (orig == NULL)  return;

   tty->print(" !orig=");

   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops

   if (NotANode(fast))  fast = NULL;

   while (orig != NULL) {

     bool discon = is_disconnected(orig);  // if discon, print [123] else 123

     if (discon)  tty->print("[");

     if (!Compile::current()->node_arena()->contains(orig))

       tty->print("o");

     tty->print("%d", orig->_idx);

     if (discon)  tty->print("]");

     orig = orig->debug_orig();

     if (NotANode(orig))  orig = NULL;

     if (orig != NULL && !C->node_arena()->contains(orig))  orig = NULL;

     if (orig != NULL)  tty->print(",");

     if (fast != NULL) {

       // Step fast twice for each single step of orig:

       fast = fast->debug_orig();

       if (NotANode(fast))  fast = NULL;

       if (fast != NULL && fast != orig) {

         fast = fast->debug_orig();

         if (NotANode(fast))  fast = NULL;

       }

       if (fast == orig) {

         tty->print("...");

         break;

       }

     }

   }

 }

 void Node::set_debug_orig(Node* orig) {

   _debug_orig = orig;

   if (BreakAtNode == 0)  return;

   if (NotANode(orig))  orig = NULL;

   int trip = 10;

   while (orig != NULL) {

     if (orig->debug_idx() == BreakAtNode || (int)orig->_idx == BreakAtNode) {

       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d orig._idx=%d orig._debug_idx=%d",

                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());

       BREAKPOINT;

     }

     orig = orig->debug_orig();

     if (NotANode(orig))  orig = NULL;

     if (trip-- <= 0)  break;

   }

 }

 #endif //ASSERT

 //------------------------------dump------------------------------------------

 // Dump a Node

 void Node::dump() const {

   Compile* C = Compile::current();

   bool is_new = C->node_arena()->contains(this);

   _in_dump_cnt++;

   tty->print("%c%d\t%s\t=== ",

              is_new ? ' ' : 'o', _idx, Name());

   // Dump the required and precedence inputs

   dump_req();

   dump_prec();

   // Dump the outputs

   dump_out();

   if (is_disconnected(this)) {

 #ifdef ASSERT

     tty->print("  [%d]",debug_idx());

     dump_orig(debug_orig());

 #endif

     tty->cr();

     _in_dump_cnt--;

     return;                     // don't process dead nodes

   }

   // Dump node-specific info

   dump_spec(tty);

 #ifdef ASSERT

   // Dump the non-reset _debug_idx

   if( Verbose && WizardMode ) {

     tty->print("  [%d]",debug_idx());

   }

 #endif

   const Type *t = bottom_type();

   if (t != NULL && (t->isa_instptr() || t->isa_klassptr())) {

     const TypeInstPtr  *toop = t->isa_instptr();

     const TypeKlassPtr *tkls = t->isa_klassptr();

     ciKlass*           klass = toop ? toop->klass() : (tkls ? tkls->klass() : NULL );

     if( klass && klass->is_loaded() && klass->is_interface() ) {

       tty->print("  Interface:");

     } else if( toop ) {

       tty->print("  Oop:");

     } else if( tkls ) {

       tty->print("  Klass:");

     }

     t->dump();

   } else if( t == Type::MEMORY ) {

     tty->print("  Memory:");

     MemNode::dump_adr_type(this, adr_type(), tty);

   } else if( Verbose || WizardMode ) {

     tty->print("  Type:");

     if( t ) {

       t->dump();

     } else {

       tty->print("no type");

     }

   }

   if (is_new) {

     debug_only(dump_orig(debug_orig()));

     Node_Notes* nn = C->node_notes_at(_idx);

     if (nn != NULL && !nn->is_clear()) {

       if (nn->jvms() != NULL) {

         tty->print(" !jvms:");

         nn->jvms()->dump_spec(tty);

       }

     }

   }

   tty->cr();

   _in_dump_cnt--;

 }

 //------------------------------dump_req--------------------------------------

 void Node::dump_req() const {

   // Dump the required input edges

   for (uint i = 0; i < req(); i++) {    // For all required inputs

     Node* d = in(i);

     if (d == NULL) {

       tty->print("_ ");

     } else if (NotANode(d)) {

       tty->print("NotANode ");  // uninitialized, sentinel, garbage, etc.

     } else {

       tty->print("%c%d ", Compile::current()->node_arena()->contains(d) ? ' ' : 'o', d->_idx);

     }

   }

 }

 //------------------------------dump_prec-------------------------------------

 void Node::dump_prec() const {

   // Dump the precedence edges

   int any_prec = 0;

   for (uint i = req(); i < len(); i++) {       // For all precedence inputs

     Node* p = in(i);

     if (p != NULL) {

       if( !any_prec++ ) tty->print(" |");

       if (NotANode(p)) { tty->print("NotANode "); continue; }

       tty->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);

     }

   }

 }

 //------------------------------dump_out--------------------------------------

 void Node::dump_out() const {

   // Delimit the output edges

   tty->print(" [[");

   // Dump the output edges

   for (uint i = 0; i < _outcnt; i++) {    // For all outputs

     Node* u = _out[i];

     if (u == NULL) {

       tty->print("_ ");

     } else if (NotANode(u)) {

       tty->print("NotANode ");

     } else {

       tty->print("%c%d ", Compile::current()->node_arena()->contains(u) ? ' ' : 'o', u->_idx);

     }

   }

   tty->print("]] ");

 }

 //------------------------------dump_nodes-------------------------------------

 static void dump_nodes(const Node* start, int d, bool only_ctrl) {

   Node* s = (Node*)start; // remove const

   if (NotANode(s)) return;

   uint depth = (uint)ABS(d);

   int direction = d;

   Compile* C = Compile::current();

   GrowableArray <Node *> nstack(C->unique());

   nstack.append(s);

   int begin = 0;

   int end = 0;

   for(uint i = 0; i < depth; i++) {

     end = nstack.length();

     for(int j = begin; j < end; j++) {

       Node* tp  = nstack.at(j);

       uint limit = direction > 0 ? tp->len() : tp->outcnt();

       for(uint k = 0; k < limit; k++) {

         Node* n = direction > 0 ? tp->in(k) : tp->raw_out(k);

         if (NotANode(n))  continue;

         // do not recurse through top or the root (would reach unrelated stuff)

         if (n->is_Root() || n->is_top())  continue;

         if (only_ctrl && !n->is_CFG()) continue;

         bool on_stack = nstack.contains(n);

         if (!on_stack) {

           nstack.append(n);

         }

       }

     }

     begin = end;

   }

   end = nstack.length();

   if (direction > 0) {

     for(int j = end-1; j >= 0; j--) {

       nstack.at(j)->dump();

     }

   } else {

     for(int j = 0; j < end; j++) {

       nstack.at(j)->dump();

     }

   }

 }

 //------------------------------dump-------------------------------------------

 void Node::dump(int d) const {

   dump_nodes(this, d, false);

 }

 //------------------------------dump_ctrl--------------------------------------

 // Dump a Node's control history to depth

 void Node::dump_ctrl(int d) const {

   dump_nodes(this, d, true);

 }

 // VERIFICATION CODE

 // For each input edge to a node (ie - for each Use-Def edge), verify that

 // there is a corresponding Def-Use edge.

 //------------------------------verify_edges-----------------------------------

 void Node::verify_edges(Unique_Node_List &visited) {

   uint i, j, idx;

   int  cnt;

   Node *n;

   // Recursive termination test

   if (visited.member(this))  return;

   visited.push(this);

   // Walk over all input edges, checking for correspondance

   for( i = 0; i < len(); i++ ) {

     n = in(i);

     if (n != NULL && !n->is_top()) {

       // Count instances of (Node *)this

       cnt = 0;

       for (idx = 0; idx < n->_outcnt; idx++ ) {

         if (n->_out[idx] == (Node *)this)  cnt++;

       }

       assert( cnt > 0,"Failed to find Def-Use edge." );

       // Check for duplicate edges

       // walk the input array downcounting the input edges to n

       for( j = 0; j < len(); j++ ) {

         if( in(j) == n ) cnt--;

       }

       assert( cnt == 0,"Mismatched edge count.");

     } else if (n == NULL) {

       assert(i >= req() || i == 0 || is_Region() || is_Phi(), "only regions or phis have null data edges");

     } else {

       assert(n->is_top(), "sanity");

       // Nothing to check.

     }

   }

   // Recursive walk over all input edges

   for( i = 0; i < len(); i++ ) {

     n = in(i);

     if( n != NULL )

       in(i)->verify_edges(visited);

   }

 }

 //------------------------------verify_recur-----------------------------------

 static const Node *unique_top = NULL;

 void Node::verify_recur(const Node *n, int verify_depth,

                         VectorSet &old_space, VectorSet &new_space) {

   if ( verify_depth == 0 )  return;

   if (verify_depth > 0)  --verify_depth;

   Compile* C = Compile::current();

   // Contained in new_space or old_space?

   VectorSet *v = C->node_arena()->contains(n) ? &new_space : &old_space;

   // Check for visited in the proper space.  Numberings are not unique

   // across spaces so we need a seperate VectorSet for each space.

   if( v->test_set(n->_idx) ) return;

   if (n->is_Con() && n->bottom_type() == Type::TOP) {

     if (C->cached_top_node() == NULL)

       C->set_cached_top_node((Node*)n);

     assert(C->cached_top_node() == n, "TOP node must be unique");

   }

   for( uint i = 0; i < n->len(); i++ ) {

     Node *x = n->in(i);

     if (!x || x->is_top()) continue;

     // Verify my input has a def-use edge to me

     if (true /*VerifyDefUse*/) {

       // Count use-def edges from n to x

       int cnt = 0;

       for( uint j = 0; j < n->len(); j++ )

         if( n->in(j) == x )

           cnt++;

       // Count def-use edges from x to n

       uint max = x->_outcnt;

       for( uint k = 0; k < max; k++ )

         if (x->_out[k] == n)

           cnt--;

       assert( cnt == 0, "mismatched def-use edge counts" );

     }

     verify_recur(x, verify_depth, old_space, new_space);

   }

 }

 //------------------------------verify-----------------------------------------

 // Check Def-Use info for my subgraph

 void Node::verify() const {

   Compile* C = Compile::current();

   Node* old_top = C->cached_top_node();

   ResourceMark rm;

   ResourceArea *area = Thread::current()->resource_area();

   VectorSet old_space(area), new_space(area);

   verify_recur(this, -1, old_space, new_space);

   C->set_cached_top_node(old_top);

 }

 #endif

 //------------------------------walk-------------------------------------------

 // Graph walk, with both pre-order and post-order functions

 void Node::walk(NFunc pre, NFunc post, void *env) {

   VectorSet visited(Thread::current()->resource_area()); // Setup for local walk

   walk_(pre, post, env, visited);

 }

 void Node::walk_(NFunc pre, NFunc post, void *env, VectorSet &visited) {

   if( visited.test_set(_idx) ) return;

   pre(*this,env);               // Call the pre-order walk function

   for( uint i=0; i<_max; i++ )

     if( in(i) )                 // Input exists and is not walked?

       in(i)->walk_(pre,post,env,visited); // Walk it with pre & post functions

   post(*this,env);              // Call the post-order walk function

 }

 void Node::nop(Node &, void*) {}

 //------------------------------Registers--------------------------------------

 // Do we Match on this edge index or not?  Generally false for Control

 // and true for everything else.  Weird for calls & returns.

 uint Node::match_edge(uint idx) const {

   return idx;                   // True for other than index 0 (control)

 }

 // Register classes are defined for specific machines

 const RegMask &Node::out_RegMask() const {

   ShouldNotCallThis();

   return *(new RegMask());

 }

 const RegMask &Node::in_RegMask(uint) const {

   ShouldNotCallThis();

   return *(new RegMask());

 }

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

 //-----------------------------------------------------------------------------

 void Node_Array::reset( Arena *new_arena ) {

   _a->Afree(_nodes,_max*sizeof(Node*));

   _max   = 0;

   _nodes = NULL;

   _a     = new_arena;

 }

 //------------------------------clear------------------------------------------

 // Clear all entries in _nodes to NULL but keep storage

 void Node_Array::clear() {

   Copy::zero_to_bytes( _nodes, _max*sizeof(Node*) );

 }

 //-----------------------------------------------------------------------------

 void Node_Array::grow( uint i ) {

   if( !_max ) {

     _max = 1;

     _nodes = (Node**)_a->Amalloc( _max * sizeof(Node*) );

     _nodes[0] = NULL;

   }

   uint old = _max;

   while( i >= _max ) _max <<= 1;        // Double to fit

   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));

   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );

 }

 //-----------------------------------------------------------------------------

 void Node_Array::insert( uint i, Node *n ) {

   if( _nodes[_max-1] ) grow(_max);      // Get more space if full

   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i+1], ((_max-i-1)*sizeof(Node*)));

   _nodes[i] = n;

 }

 //-----------------------------------------------------------------------------

 void Node_Array::remove( uint i ) {

   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i+1], (HeapWord*)&_nodes[i], ((_max-i-1)*sizeof(Node*)));

   _nodes[_max-1] = NULL;

 }

 //-----------------------------------------------------------------------------

 void Node_Array::sort( C_sort_func_t func) {

   qsort( _nodes, _max, sizeof( Node* ), func );

 }

 //-----------------------------------------------------------------------------

 void Node_Array::dump() const {

 #ifndef PRODUCT

   for( uint i = 0; i < _max; i++ ) {

     Node *nn = _nodes[i];

     if( nn != NULL ) {

       tty->print("%5d--> ",i); nn->dump();

     }

   }

 #endif

 }

 //--------------------------is_iteratively_computed------------------------------

 // Operation appears to be iteratively computed (such as an induction variable)

 // It is possible for this operation to return false for a loop-varying

 // value, if it appears (by local graph inspection) to be computed by a simple conditional.

 bool Node::is_iteratively_computed() {

   if (ideal_reg()) { // does operation have a result register?

     for (uint i = 1; i < req(); i++) {

       Node* n = in(i);

       if (n != NULL && n->is_Phi()) {

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

           if (n->in(j) == this) {

             return true;

           }

         }

       }

     }

   }

   return false;

 }

 //--------------------------find_similar------------------------------

 // Return a node with opcode "opc" and same inputs as "this" if one can

 // be found; Otherwise return NULL;

 Node* Node::find_similar(int opc) {

   if (req() >= 2) {

     Node* def = in(1);

     if (def && def->outcnt() >= 2) {

       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {

         Node* use = def->fast_out(i);

         if (use->Opcode() == opc &&

             use->req() == req()) {

           uint j;

           for (j = 0; j < use->req(); j++) {

             if (use->in(j) != in(j)) {

               break;

             }

           }

           if (j == use->req()) {

             return use;

           }

         }

       }

     }

   }

   return NULL;

 }

 //--------------------------unique_ctrl_out------------------------------

 // Return the unique control out if only one. Null if none or more than one.

 Node* Node::unique_ctrl_out() {

   Node* found = NULL;

   for (uint i = 0; i < outcnt(); i++) {

     Node* use = raw_out(i);

     if (use->is_CFG() && use != this) {

       if (found != NULL) return NULL;

       found = use;

     }

   }

   return found;

 }

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

 //------------------------------yank-------------------------------------------

 // Find and remove

 void Node_List::yank( Node *n ) {

   uint i;

   for( i = 0; i < _cnt; i++ )

     if( _nodes[i] == n )

       break;

   if( i < _cnt )

     _nodes[i] = _nodes[--_cnt];

 }

 //------------------------------dump-------------------------------------------

 void Node_List::dump() const {

 #ifndef PRODUCT

   for( uint i = 0; i < _cnt; i++ )

     if( _nodes[i] ) {

       tty->print("%5d--> ",i);

       _nodes[i]->dump();

     }

 #endif

 }

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

 //------------------------------remove-----------------------------------------

 void Unique_Node_List::remove( Node *n ) {

   if( _in_worklist[n->_idx] ) {

     for( uint i = 0; i < size(); i++ )

       if( _nodes[i] == n ) {

         map(i,Node_List::pop());

         _in_worklist >>= n->_idx;

         return;

       }

     ShouldNotReachHere();

   }

 }

 //-----------------------remove_useless_nodes----------------------------------

 // Remove useless nodes from worklist

 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {

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

     Node *n = at(i);

     assert( n != NULL, "Did not expect null entries in worklist");

     if( ! useful.test(n->_idx) ) {

       _in_worklist >>= n->_idx;

       map(i,Node_List::pop());

       // Node *replacement = Node_List::pop();

       // if( i != size() ) { // Check if removing last entry

       //   _nodes[i] = replacement;

       // }

       --i;  // Visit popped node

       // If it was last entry, loop terminates since size() was also reduced

     }

   }

 }

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

 void Node_Stack::grow() {

   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top

   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));

   size_t max = old_max << 1;             // max * 2

   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);

   _inode_max = _inodes + max;

   _inode_top = _inodes + old_top;        // restore _top

 }

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

 uint TypeNode::size_of() const { return sizeof(*this); }

 #ifndef PRODUCT

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

   if( !Verbose && !WizardMode ) {

     // standard dump does this in Verbose and WizardMode

     st->print(" #"); _type->dump_on(st);

   }

 }

 #endif

 uint TypeNode::hash() const {

   return Node::hash() + _type->hash();

 }

 uint TypeNode::cmp( const Node &n ) const

 { return !Type::cmp( _type, ((TypeNode&)n)._type ); }

 const Type *TypeNode::bottom_type() const { return _type; }

 const Type *TypeNode::Value( PhaseTransform * ) const { return _type; }

 //------------------------------ideal_reg--------------------------------------

 uint TypeNode::ideal_reg() const {

   return Matcher::base2reg[_type->base()];

 }