jdk8-mips64-public/hotspot: src/share/vm/opto/node.cpp@eb7ce841ccec (annotated)

src/share/vm/opto/node.cpp@eb7ce841ccec (annotated)

src/share/vm/opto/node.cpp

Sat, 24 Oct 2020 16:43:47 +0800

author: aoqi
date: Sat, 24 Oct 2020 16:43:47 +0800
changeset 10015: eb7ce841ccec
parent 9931: fd44df5e3bc3
parent 9957: d2ec2776ad0c
permissions: -rw-r--r--

Merge

 /*
  * Copyright (c) 1997, 2016, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #include "precompiled.hpp"
 #include "libadt/vectset.hpp"
 #include "memory/allocation.inline.hpp"
 #include "opto/cfgnode.hpp"
 #include "opto/connode.hpp"
 #include "opto/loopnode.hpp"
 #include "opto/machnode.hpp"
 #include "opto/matcher.hpp"
 #include "opto/node.hpp"
 #include "opto/opcodes.hpp"
 #include "opto/regmask.hpp"
 #include "opto/type.hpp"
 #include "utilities/copy.hpp"
 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 those 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() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
   assert(Compile::current()->live_nodes() < Compile::current()->max_node_limit(), "Live Node limit exceeded limit");
   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
 #ifdef __clang__
 #pragma clang diagnostic push
 #pragma GCC diagnostic ignored "-Wuninitialized"
 #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();
   // Allocate memory for the necessary number of edges.
   if (req > 0) {
     // Allocate space for _in array to have double alignment.
     _in = (Node **) ((char *) (C->node_arena()->Amalloc_D(req * sizeof(void*))));
 #ifdef ASSERT
     _in[req-1] = this; // magic cookie for assertion check
 #endif
   }
   // 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))
 #ifdef ASSERT
   , _parse_idx(_idx)
 #endif
 {
   assert( req < Compile::current()->max_node_limit() - 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))
 #ifdef ASSERT
   , _parse_idx(_idx)
 #endif
 {
   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))
 #ifdef ASSERT
   , _parse_idx(_idx)
 #endif
 {
   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))
 #ifdef ASSERT
   , _parse_idx(_idx)
 #endif
 {
   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))
 #ifdef ASSERT
   , _parse_idx(_idx)
 #endif
 {
   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))
 #ifdef ASSERT
   , _parse_idx(_idx)
 #endif
 {
   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))
 #ifdef ASSERT
   , _parse_idx(_idx)
 #endif
 {
   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))
 #ifdef ASSERT
   , _parse_idx(_idx)
 #endif
 {
   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);
 }
 #ifdef __clang__
 #pragma clang diagnostic pop
 #endif
 //------------------------------clone------------------------------------------
 // Clone a Node.
 Node *Node::clone() const {
   Compile* C = Compile::current();
   uint s = size_of();           // Size of inherited Node
   Node *n = (Node*)C->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())
     C->add_macro_node(n);
   if (is_expensive())
     C->add_expensive_node(n);
   // If the cloned node is a range check dependent CastII, add it to the list.
   CastIINode* cast = n->isa_CastII();
   if (cast != NULL && cast->has_range_check()) {
     C->add_range_check_cast(cast);
   }
   n->set_idx(C->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() ) );
   C->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(C);
     }
   }
   // cloning CallNode may need to clone JVMState
   if (n->is_Call()) {
     n->as_Call()->clone_jvms(C);
   }
   if (n->is_SafePoint()) {
     n->as_SafePoint()->clone_replaced_nodes();
   }
   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);
   }
   if (is_expensive()) {
     compile->remove_expensive_node(this);
   }
   CastIINode* cast = isa_CastII();
   if (cast != NULL && cast->has_range_check()) {
     compile->remove_range_check_cast(cast);
   }
   if (is_SafePoint()) {
     as_SafePoint()->delete_replaced_nodes();
   }
 #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
 //------------------------------is_unreachable---------------------------------
 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
   assert(!is_Mach(), "doesn't work with MachNodes");
   return outcnt() == 0 || igvn.type(this) == Type::TOP || in(0)->is_top();
 }
 //------------------------------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 ) {
   assert( idx < _cnt, "oob");
   assert( !VerifyHashTableKeys || _hash_lock == 0,
           "remove node from hash table before modifying it");
   // 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
   // Avoid spec violation: Gap in prec edges.
   close_prec_gap_at(_cnt);
 }
 //------------------------------del_req_ordered--------------------------------
 // Delete the required edge and compact the edge array with preserved order
 void Node::del_req_ordered( uint idx ) {
   assert( idx < _cnt, "oob");
   assert( !VerifyHashTableKeys || _hash_lock == 0,
           "remove node from hash table before modifying it");
   // First remove corresponding def-use edge
   Node *n = in(idx);
   if (n != NULL) n->del_out((Node *)this);
   if (idx < --_cnt) {    // Not last edge ?
     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
   }
   // Avoid spec violation: Gap in prec edges.
   close_prec_gap_at(_cnt);
 }
 //------------------------------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 {
         assert(find_prec_edge(neww) == -1, err_msg("spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx));
         set_prec(i, neww);
       }
       nrep++;
     }
   }
   return nrep;
 }
 /**
  * Replace input edges in the range pointing to 'old' node.
  */
 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end) {
   if (old == neww)  return 0;  // nothing to do
   uint nrep = 0;
   for (int i = start; i < end; i++) {
     if (in(i) == old) {
       set_req(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, Compile* C) {
   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
   if (edges_to_n == 0) {
     C->record_dead_node(_idx);
   }
   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;
 }
 // Find out of current node that matches opcode.
 Node* Node::find_out_with(int opcode) {
   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
     Node* use = fast_out(i);
     if (use->Opcode() == opcode) {
       return use;
     }
   }
   return NULL;
 }
 //---------------------------uncast_helper-------------------------------------
 Node* Node::uncast_helper(const Node* p) {
 #ifdef ASSERT
   uint depth_count = 0;
   const Node* orig_p = p;
 #endif
   while (true) {
 #ifdef ASSERT
     if (depth_count >= K) {
       orig_p->dump(4);
       if (p != orig_p)
         p->dump(1);
     }
     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
 #endif
     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 ) {
     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
     i++;
   }
   _in[i] = n;                                // Stuff prec edge over NULL
   if ( n != NULL) n->add_out((Node *)this);  // Add mirror edge
 #ifdef ASSERT
   while ((++i)<_max) { assert(_in[i] == NULL, err_msg("spec violation: Gap in prec edges (node %d)", _idx)); }
 #endif
 }
 //------------------------------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 ) {
   assert(j < _max, err_msg("oob: i=%d, _max=%d", j, _max));
   assert(j >= _cnt, "not a precedence edge");
   if (_in[j] == NULL) return;   // Avoid spec violation: Gap in prec edges.
   _in[j]->del_out((Node *)this);
   close_prec_gap_at(j);
 }
 //------------------------------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_speculative(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_speculative(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 should use
 // 'set_req'.  If you are making a new Node (either as the new root or
 // some new internal piece) you may use 'init_req' to set the initial
 // value.  You can make a new Node with either 'new' or 'clone'.  In
 // either case, def-use info is correctly maintained.
 //
 // Example: reshape "(X+3)+4" into "X+7":
 //    set_req(1, in(1)->in(1));
 //    set_req(2, phase->intcon(7));
 //    return this;
 // Example: reshape "X*4" into "X<<2"
 //    return new (C) LShiftINode(in(1), phase->intcon(2));
 //
 // 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)-X".
 //    Node *shift=phase->transform(new(C)LShiftINode(in(1),phase->intcon(5)));
 //    return new (C) AddINode(shift, in(1));
 //
 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
 // These forms are faster than 'phase->transform(new (C) 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 (this->is_Load()) {
     // Condition for removing an unused LoadNode from the MemBarAcquire precedence input
     return n->Opcode() == Op_MemBarAcquire;
   } 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;
 };
 //--------------------------find_exact_control---------------------------------
 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
 Node* Node::find_exact_control(Node* ctrl) {
   if (ctrl == NULL && this->is_Region())
     ctrl = this->as_Region()->is_copy();
   if (ctrl != NULL && ctrl->is_CatchProj()) {
     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
       ctrl = ctrl->in(0);
     if (ctrl != NULL && !ctrl->is_top())
       ctrl = ctrl->in(0);
   }
   if (ctrl != NULL && ctrl->is_Proj())
     ctrl = ctrl->in(0);
   return ctrl;
 }
 //--------------------------dominates------------------------------------------
 // Helper function for MemNode::all_controls_dominate().
 // Check if 'this' control node dominates or equal to 'sub' control node.
 // We already know that if any path back to Root or Start reaches 'this',
 // then all paths so, so this is a simple search for one example,
 // not an exhaustive search for a counterexample.
 bool Node::dominates(Node* sub, Node_List &nlist) {
   assert(this->is_CFG(), "expecting control");
   assert(sub != NULL && sub->is_CFG(), "expecting control");
   // detect dead cycle without regions
   int iterations_without_region_limit = DominatorSearchLimit;
   Node* orig_sub = sub;
   Node* dom      = this;
   bool  met_dom  = false;
   nlist.clear();
   // Walk 'sub' backward up the chain to 'dom', watching for regions.
   // After seeing 'dom', continue up to Root or Start.
   // If we hit a region (backward split point), it may be a loop head.
   // Keep going through one of the region's inputs.  If we reach the
   // same region again, go through a different input.  Eventually we
   // will either exit through the loop head, or give up.
   // (If we get confused, break out and return a conservative 'false'.)
   while (sub != NULL) {
     if (sub->is_top())  break; // Conservative answer for dead code.
     if (sub == dom) {
       if (nlist.size() == 0) {
         // No Region nodes except loops were visited before and the EntryControl
         // path was taken for loops: it did not walk in a cycle.
         return true;
       } else if (met_dom) {
         break;          // already met before: walk in a cycle
       } else {
         // Region nodes were visited. Continue walk up to Start or Root
         // to make sure that it did not walk in a cycle.
         met_dom = true; // first time meet
         iterations_without_region_limit = DominatorSearchLimit; // Reset
      }
     }
     if (sub->is_Start() || sub->is_Root()) {
       // Success if we met 'dom' along a path to Start or Root.
       // We assume there are no alternative paths that avoid 'dom'.
       // (This assumption is up to the caller to ensure!)
       return met_dom;
     }
     Node* up = sub->in(0);
     // Normalize simple pass-through regions and projections:
     up = sub->find_exact_control(up);
     // If sub == up, we found a self-loop.  Try to push past it.
     if (sub == up && sub->is_Loop()) {
       // Take loop entry path on the way up to 'dom'.
       up = sub->in(1); // in(LoopNode::EntryControl);
     } else if (sub == up && sub->is_Region() && sub->req() != 3) {
       // Always take in(1) path on the way up to 'dom' for clone regions
       // (with only one input) or regions which merge > 2 paths
       // (usually used to merge fast/slow paths).
       up = sub->in(1);
     } else if (sub == up && sub->is_Region()) {
       // Try both paths for Regions with 2 input paths (it may be a loop head).
       // It could give conservative 'false' answer without information
       // which region's input is the entry path.
       iterations_without_region_limit = DominatorSearchLimit; // Reset
       bool region_was_visited_before = false;
       // Was this Region node visited before?
       // If so, we have reached it because we accidentally took a
       // loop-back edge from 'sub' back into the body of the loop,
       // and worked our way up again to the loop header 'sub'.
       // So, take the first unexplored path on the way up to 'dom'.
       for (int j = nlist.size() - 1; j >= 0; j--) {
         intptr_t ni = (intptr_t)nlist.at(j);
         Node* visited = (Node*)(ni & ~1);
         bool  visited_twice_already = ((ni & 1) != 0);
         if (visited == sub) {
           if (visited_twice_already) {
             // Visited 2 paths, but still stuck in loop body.  Give up.
             return false;
           }
           // The Region node was visited before only once.
           // (We will repush with the low bit set, below.)
           nlist.remove(j);
           // We will find a new edge and re-insert.
           region_was_visited_before = true;
           break;
         }
       }
       // Find an incoming edge which has not been seen yet; walk through it.
       assert(up == sub, "");
       uint skip = region_was_visited_before ? 1 : 0;
       for (uint i = 1; i < sub->req(); i++) {
         Node* in = sub->in(i);
         if (in != NULL && !in->is_top() && in != sub) {
           if (skip == 0) {
             up = in;
             break;
           }
           --skip;               // skip this nontrivial input
         }
       }
       // Set 0 bit to indicate that both paths were taken.
       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
     }
     if (up == sub) {
       break;    // some kind of tight cycle
     }
     if (up == orig_sub && met_dom) {
       // returned back after visiting 'dom'
       break;    // some kind of cycle
     }
     if (--iterations_without_region_limit < 0) {
       break;    // dead cycle
     }
     sub = up;
   }
   // Did not meet Root or Start node in pred. chain.
   // Conservative answer for dead code.
   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 void 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;
   // 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();
   nstack.push(dead);
   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
   while (nstack.size() > 0) {
     dead = nstack.pop();
     if (dead->Opcode() == Op_SafePoint) {
       dead->as_SafePoint()->disconnect_from_root(igvn);
     }
     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 if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
           use->set_req(0, top);       // Cut self edge
           nstack.push(use);
         } else {                      // Else found a not-dead user
           // Dead if all inputs are top or null
           bool dead_use = !use->is_Root(); // Keep empty graph alive
           for (uint j = 1; j < use->req(); j++) {
             Node* in = use->in(j);
             if (in == dead) {         // Turn all dead inputs into TOP
               use->set_req(j, top);
             } else if (in != NULL && !in->is_top()) {
               dead_use = false;
             }
           }
           if (dead_use) {
             if (use->is_Region()) {
               use->set_req(0, top);   // Cut self edge
             }
             nstack.push(use);
           } else {
             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);
       }
       if (dead->is_expensive()) {
         igvn->C->remove_expensive_node(dead);
       }
       CastIINode* cast = dead->isa_CastII();
       if (cast != NULL && cast->has_range_check()) {
         igvn->C->remove_range_check_cast(cast);
       }
       igvn->C->record_dead_node(dead->_idx);
       // 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?
           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;
 }
 //------------------------------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()) {
     kill_dead_code(this, phase->is_IterGVN());
     return false; // Node is dead.
   }
   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;
 }
 /**
  * Return a ptr type for nodes which should have it.
  */
 const TypePtr* Node::get_ptr_type() const {
   const TypePtr* tp = this->bottom_type()->make_ptr();
 #ifdef ASSERT
   if (tp == NULL) {
     this->dump(1);
     assert((tp != NULL), "unexpected node type");
   }
 #endif
   return tp;
 }
 // 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(Compile* C,  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?   Check old_arena first since it's mostly empty.
   VectorSet *v = C->old_arena()->contains(n) ? old_space : new_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(C, 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(C, result, n->raw_out(j), idx, only_ctrl, old_space, new_space );
     }
   }
 #ifdef ASSERT
   // Search along debug_orig edges last, checking for cycles
   Node* orig = n->debug_orig();
   if (orig != NULL) {
     do {
       if (NotANode(orig))  break;
       find_recur(C, result, orig, idx, only_ctrl, old_space, new_space );
       orig = orig->debug_orig();
     } while (orig != NULL && orig != n->debug_orig());
   }
 #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(Compile::current(), 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(Compile::current(), result, (Node*) this, idx, true, &old_space, &new_space );
   return result;
 }
 #endif
 #ifndef PRODUCT
 // -----------------------------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, outputStream *st) {
   Compile* C = Compile::current();
   if (NotANode(orig)) orig = NULL;
   if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
   if (orig == NULL) return;
   st->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) st->print("[");
     if (!Compile::current()->node_arena()->contains(orig))
       st->print("o");
     st->print("%d", orig->_idx);
     if (discon) st->print("]");
     orig = orig->debug_orig();
     if (NotANode(orig)) orig = NULL;
     if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
     if (orig != NULL) st->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) {
         st->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 char* suffix, outputStream *st) const {
   Compile* C = Compile::current();
   bool is_new = C->node_arena()->contains(this);
   C->_in_dump_cnt++;
   st->print("%c%d\t%s\t=== ", is_new ? ' ' : 'o', _idx, Name());
   // Dump the required and precedence inputs
   dump_req(st);
   dump_prec(st);
   // Dump the outputs
   dump_out(st);
   if (is_disconnected(this)) {
 #ifdef ASSERT
     st->print("  [%d]",debug_idx());
     dump_orig(debug_orig(), st);
 #endif
     st->cr();
     C->_in_dump_cnt--;
     return;                     // don't process dead nodes
   }
   // Dump node-specific info
   dump_spec(st);
 #ifdef ASSERT
   // Dump the non-reset _debug_idx
   if (Verbose && WizardMode) {
     st->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()) {
       st->print("  Interface:");
     } else if (toop) {
       st->print("  Oop:");
     } else if (tkls) {
       st->print("  Klass:");
     }
     t->dump_on(st);
   } else if (t == Type::MEMORY) {
     st->print("  Memory:");
     MemNode::dump_adr_type(this, adr_type(), st);
   } else if (Verbose || WizardMode) {
     st->print("  Type:");
     if (t) {
       t->dump_on(st);
     } else {
       st->print("no type");
     }
   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
     // Dump MachSpillcopy vector type.
     t->dump_on(st);
   }
   if (is_new) {
     debug_only(dump_orig(debug_orig(), st));
     Node_Notes* nn = C->node_notes_at(_idx);
     if (nn != NULL && !nn->is_clear()) {
       if (nn->jvms() != NULL) {
         st->print(" !jvms:");
         nn->jvms()->dump_spec(st);
       }
     }
   }
   if (suffix) st->print("%s", suffix);
   C->_in_dump_cnt--;
 }
 //------------------------------dump_req--------------------------------------
 void Node::dump_req(outputStream *st) const {
   // Dump the required input edges
   for (uint i = 0; i < req(); i++) {    // For all required inputs
     Node* d = in(i);
     if (d == NULL) {
       st->print("_ ");
     } else if (NotANode(d)) {
       st->print("NotANode ");  // uninitialized, sentinel, garbage, etc.
     } else {
       st->print("%c%d ", Compile::current()->node_arena()->contains(d) ? ' ' : 'o', d->_idx);
     }
   }
 }
 //------------------------------dump_prec-------------------------------------
 void Node::dump_prec(outputStream *st) 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++) st->print(" |");
       if (NotANode(p)) { st->print("NotANode "); continue; }
       st->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
     }
   }
 }
 //------------------------------dump_out--------------------------------------
 void Node::dump_out(outputStream *st) const {
   // Delimit the output edges
   st->print(" [[");
   // Dump the output edges
   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
     Node* u = _out[i];
     if (u == NULL) {
       st->print("_ ");
     } else if (NotANode(u)) {
       st->print("NotANode ");
     } else {
       st->print("%c%d ", Compile::current()->node_arena()->contains(u) ? ' ' : 'o', u->_idx);
     }
   }
   st->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->live_nodes());
   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 correspondence
   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 separate 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)
 }
 static RegMask _not_used_at_all;
 // Register classes are defined for specific machines
 const RegMask &Node::out_RegMask() const {
   ShouldNotCallThis();
   return _not_used_at_all;
 }
 const RegMask &Node::in_RegMask(uint) const {
   ShouldNotCallThis();
   return _not_used_at_all;
 }
 //=============================================================================
 //-----------------------------------------------------------------------------
 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
 }
 void Node_List::dump_simple() const {
 #ifndef PRODUCT
   for( uint i = 0; i < _cnt; i++ )
     if( _nodes[i] ) {
       tty->print(" %d", _nodes[i]->_idx);
     } else {
       tty->print(" NULL");
     }
 #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
 }
 // Node_Stack is used to map nodes.
 Node* Node_Stack::find(uint idx) const {
   uint sz = size();
   for (uint i=0; i < sz; i++) {
     if (idx == index_at(i) )
       return node_at(i);
   }
   return NULL;
 }
 //=============================================================================
 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 _type->ideal_reg();
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/opto/node.cpp@eb7ce841ccec (annotated)

src/share/vm/opto/node.cpp