1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/barrierSet.hpp"
  27 #include "gc/shared/c2/barrierSetC2.hpp"
  28 #include "libadt/vectset.hpp"
  29 #include "memory/allocation.inline.hpp"
  30 #include "memory/resourceArea.hpp"
  31 #include "opto/castnode.hpp"
  32 #include "opto/cfgnode.hpp"
  33 #include "opto/connode.hpp"
  34 #include "opto/loopnode.hpp"
  35 #include "opto/machnode.hpp"
  36 #include "opto/matcher.hpp"
  37 #include "opto/node.hpp"
  38 #include "opto/opcodes.hpp"
  39 #include "opto/regmask.hpp"
  40 #include "opto/type.hpp"
  41 #include "utilities/copy.hpp"
  42 #include "utilities/macros.hpp"
  43 #if INCLUDE_SHENANDOAHGC
  44 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
  45 #endif
  46 
  47 class RegMask;
  48 // #include "phase.hpp"
  49 class PhaseTransform;
  50 class PhaseGVN;
  51 
  52 // Arena we are currently building Nodes in
  53 const uint Node::NotAMachineReg = 0xffff0000;
  54 
  55 #ifndef PRODUCT
  56 extern int nodes_created;
  57 #endif
  58 #ifdef __clang__
  59 #pragma clang diagnostic push
  60 #pragma GCC diagnostic ignored "-Wuninitialized"
  61 #endif
  62 
  63 #ifdef ASSERT
  64 
  65 //-------------------------- construct_node------------------------------------
  66 // Set a breakpoint here to identify where a particular node index is built.
  67 void Node::verify_construction() {
  68   _debug_orig = NULL;
  69   int old_debug_idx = Compile::debug_idx();
  70   int new_debug_idx = old_debug_idx+1;
  71   if (new_debug_idx > 0) {
  72     // Arrange that the lowest five decimal digits of _debug_idx
  73     // will repeat those of _idx. In case this is somehow pathological,
  74     // we continue to assign negative numbers (!) consecutively.
  75     const int mod = 100000;
  76     int bump = (int)(_idx - new_debug_idx) % mod;
  77     if (bump < 0)  bump += mod;
  78     assert(bump >= 0 && bump < mod, "");
  79     new_debug_idx += bump;
  80   }
  81   Compile::set_debug_idx(new_debug_idx);
  82   set_debug_idx( new_debug_idx );
  83   assert(Compile::current()->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  84   assert(Compile::current()->live_nodes() < Compile::current()->max_node_limit(), "Live Node limit exceeded limit");
  85   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (int)_idx == BreakAtNode)) {
  86     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d", _idx, _debug_idx);
  87     BREAKPOINT;
  88   }
  89 #if OPTO_DU_ITERATOR_ASSERT
  90   _last_del = NULL;
  91   _del_tick = 0;
  92 #endif
  93   _hash_lock = 0;
  94 }
  95 
  96 
  97 // #ifdef ASSERT ...
  98 
  99 #if OPTO_DU_ITERATOR_ASSERT
 100 void DUIterator_Common::sample(const Node* node) {
 101   _vdui     = VerifyDUIterators;
 102   _node     = node;
 103   _outcnt   = node->_outcnt;
 104   _del_tick = node->_del_tick;
 105   _last     = NULL;
 106 }
 107 
 108 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
 109   assert(_node     == node, "consistent iterator source");
 110   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
 111 }
 112 
 113 void DUIterator_Common::verify_resync() {
 114   // Ensure that the loop body has just deleted the last guy produced.
 115   const Node* node = _node;
 116   // Ensure that at least one copy of the last-seen edge was deleted.
 117   // Note:  It is OK to delete multiple copies of the last-seen edge.
 118   // Unfortunately, we have no way to verify that all the deletions delete
 119   // that same edge.  On this point we must use the Honor System.
 120   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 121   assert(node->_last_del == _last, "must have deleted the edge just produced");
 122   // We liked this deletion, so accept the resulting outcnt and tick.
 123   _outcnt   = node->_outcnt;
 124   _del_tick = node->_del_tick;
 125 }
 126 
 127 void DUIterator_Common::reset(const DUIterator_Common& that) {
 128   if (this == &that)  return;  // ignore assignment to self
 129   if (!_vdui) {
 130     // We need to initialize everything, overwriting garbage values.
 131     _last = that._last;
 132     _vdui = that._vdui;
 133   }
 134   // Note:  It is legal (though odd) for an iterator over some node x
 135   // to be reassigned to iterate over another node y.  Some doubly-nested
 136   // progress loops depend on being able to do this.
 137   const Node* node = that._node;
 138   // Re-initialize everything, except _last.
 139   _node     = node;
 140   _outcnt   = node->_outcnt;
 141   _del_tick = node->_del_tick;
 142 }
 143 
 144 void DUIterator::sample(const Node* node) {
 145   DUIterator_Common::sample(node);      // Initialize the assertion data.
 146   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 147 }
 148 
 149 void DUIterator::verify(const Node* node, bool at_end_ok) {
 150   DUIterator_Common::verify(node, at_end_ok);
 151   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 152 }
 153 
 154 void DUIterator::verify_increment() {
 155   if (_refresh_tick & 1) {
 156     // We have refreshed the index during this loop.
 157     // Fix up _idx to meet asserts.
 158     if (_idx > _outcnt)  _idx = _outcnt;
 159   }
 160   verify(_node, true);
 161 }
 162 
 163 void DUIterator::verify_resync() {
 164   // Note:  We do not assert on _outcnt, because insertions are OK here.
 165   DUIterator_Common::verify_resync();
 166   // Make sure we are still in sync, possibly with no more out-edges:
 167   verify(_node, true);
 168 }
 169 
 170 void DUIterator::reset(const DUIterator& that) {
 171   if (this == &that)  return;  // self assignment is always a no-op
 172   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 173   assert(that._idx          == 0, "assign only the result of Node::outs()");
 174   assert(_idx               == that._idx, "already assigned _idx");
 175   if (!_vdui) {
 176     // We need to initialize everything, overwriting garbage values.
 177     sample(that._node);
 178   } else {
 179     DUIterator_Common::reset(that);
 180     if (_refresh_tick & 1) {
 181       _refresh_tick++;                  // Clear the "was refreshed" flag.
 182     }
 183     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 184   }
 185 }
 186 
 187 void DUIterator::refresh() {
 188   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 189   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 190 }
 191 
 192 void DUIterator::verify_finish() {
 193   // If the loop has killed the node, do not require it to re-run.
 194   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 195   // If this assert triggers, it means that a loop used refresh_out_pos
 196   // to re-synch an iteration index, but the loop did not correctly
 197   // re-run itself, using a "while (progress)" construct.
 198   // This iterator enforces the rule that you must keep trying the loop
 199   // until it "runs clean" without any need for refreshing.
 200   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 201 }
 202 
 203 
 204 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 205   DUIterator_Common::verify(node, at_end_ok);
 206   Node** out    = node->_out;
 207   uint   cnt    = node->_outcnt;
 208   assert(cnt == _outcnt, "no insertions allowed");
 209   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 210   // This last check is carefully designed to work for NO_OUT_ARRAY.
 211 }
 212 
 213 void DUIterator_Fast::verify_limit() {
 214   const Node* node = _node;
 215   verify(node, true);
 216   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 217 }
 218 
 219 void DUIterator_Fast::verify_resync() {
 220   const Node* node = _node;
 221   if (_outp == node->_out + _outcnt) {
 222     // Note that the limit imax, not the pointer i, gets updated with the
 223     // exact count of deletions.  (For the pointer it's always "--i".)
 224     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 225     // This is a limit pointer, with a name like "imax".
 226     // Fudge the _last field so that the common assert will be happy.
 227     _last = (Node*) node->_last_del;
 228     DUIterator_Common::verify_resync();
 229   } else {
 230     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 231     // A normal internal pointer.
 232     DUIterator_Common::verify_resync();
 233     // Make sure we are still in sync, possibly with no more out-edges:
 234     verify(node, true);
 235   }
 236 }
 237 
 238 void DUIterator_Fast::verify_relimit(uint n) {
 239   const Node* node = _node;
 240   assert((int)n > 0, "use imax -= n only with a positive count");
 241   // This must be a limit pointer, with a name like "imax".
 242   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 243   // The reported number of deletions must match what the node saw.
 244   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 245   // Fudge the _last field so that the common assert will be happy.
 246   _last = (Node*) node->_last_del;
 247   DUIterator_Common::verify_resync();
 248 }
 249 
 250 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 251   assert(_outp              == that._outp, "already assigned _outp");
 252   DUIterator_Common::reset(that);
 253 }
 254 
 255 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 256   // at_end_ok means the _outp is allowed to underflow by 1
 257   _outp += at_end_ok;
 258   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 259   _outp -= at_end_ok;
 260   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 261 }
 262 
 263 void DUIterator_Last::verify_limit() {
 264   // Do not require the limit address to be resynched.
 265   //verify(node, true);
 266   assert(_outp == _node->_out, "limit still correct");
 267 }
 268 
 269 void DUIterator_Last::verify_step(uint num_edges) {
 270   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 271   _outcnt   -= num_edges;
 272   _del_tick += num_edges;
 273   // Make sure we are still in sync, possibly with no more out-edges:
 274   const Node* node = _node;
 275   verify(node, true);
 276   assert(node->_last_del == _last, "must have deleted the edge just produced");
 277 }
 278 
 279 #endif //OPTO_DU_ITERATOR_ASSERT
 280 
 281 
 282 #endif //ASSERT
 283 
 284 
 285 // This constant used to initialize _out may be any non-null value.
 286 // The value NULL is reserved for the top node only.
 287 #define NO_OUT_ARRAY ((Node**)-1)
 288 
 289 // Out-of-line code from node constructors.
 290 // Executed only when extra debug info. is being passed around.
 291 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 292   C->set_node_notes_at(idx, nn);
 293 }
 294 
 295 // Shared initialization code.
 296 inline int Node::Init(int req) {
 297   Compile* C = Compile::current();
 298   int idx = C->next_unique();
 299 
 300   // Allocate memory for the necessary number of edges.
 301   if (req > 0) {
 302     // Allocate space for _in array to have double alignment.
 303     _in = (Node **) ((char *) (C->node_arena()->Amalloc_D(req * sizeof(void*))));
 304   }
 305   // If there are default notes floating around, capture them:
 306   Node_Notes* nn = C->default_node_notes();
 307   if (nn != NULL)  init_node_notes(C, idx, nn);
 308 
 309   // Note:  At this point, C is dead,
 310   // and we begin to initialize the new Node.
 311 
 312   _cnt = _max = req;
 313   _outcnt = _outmax = 0;
 314   _class_id = Class_Node;
 315   _flags = 0;
 316   _out = NO_OUT_ARRAY;
 317   return idx;
 318 }
 319 
 320 //------------------------------Node-------------------------------------------
 321 // Create a Node, with a given number of required edges.
 322 Node::Node(uint req)
 323   : _idx(Init(req))
 324 #ifdef ASSERT
 325   , _parse_idx(_idx)
 326 #endif
 327 {
 328   assert( req < Compile::current()->max_node_limit() - NodeLimitFudgeFactor, "Input limit exceeded" );
 329   debug_only( verify_construction() );
 330   NOT_PRODUCT(nodes_created++);
 331   if (req == 0) {
 332     _in = NULL;
 333   } else {
 334     Node** to = _in;
 335     for(uint i = 0; i < req; i++) {
 336       to[i] = NULL;
 337     }
 338   }
 339 }
 340 
 341 //------------------------------Node-------------------------------------------
 342 Node::Node(Node *n0)
 343   : _idx(Init(1))
 344 #ifdef ASSERT
 345   , _parse_idx(_idx)
 346 #endif
 347 {
 348   debug_only( verify_construction() );
 349   NOT_PRODUCT(nodes_created++);
 350   assert( is_not_dead(n0), "can not use dead node");
 351   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 352 }
 353 
 354 //------------------------------Node-------------------------------------------
 355 Node::Node(Node *n0, Node *n1)
 356   : _idx(Init(2))
 357 #ifdef ASSERT
 358   , _parse_idx(_idx)
 359 #endif
 360 {
 361   debug_only( verify_construction() );
 362   NOT_PRODUCT(nodes_created++);
 363   assert( is_not_dead(n0), "can not use dead node");
 364   assert( is_not_dead(n1), "can not use dead node");
 365   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 366   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 367 }
 368 
 369 //------------------------------Node-------------------------------------------
 370 Node::Node(Node *n0, Node *n1, Node *n2)
 371   : _idx(Init(3))
 372 #ifdef ASSERT
 373   , _parse_idx(_idx)
 374 #endif
 375 {
 376   debug_only( verify_construction() );
 377   NOT_PRODUCT(nodes_created++);
 378   assert( is_not_dead(n0), "can not use dead node");
 379   assert( is_not_dead(n1), "can not use dead node");
 380   assert( is_not_dead(n2), "can not use dead node");
 381   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 382   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 383   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 384 }
 385 
 386 //------------------------------Node-------------------------------------------
 387 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 388   : _idx(Init(4))
 389 #ifdef ASSERT
 390   , _parse_idx(_idx)
 391 #endif
 392 {
 393   debug_only( verify_construction() );
 394   NOT_PRODUCT(nodes_created++);
 395   assert( is_not_dead(n0), "can not use dead node");
 396   assert( is_not_dead(n1), "can not use dead node");
 397   assert( is_not_dead(n2), "can not use dead node");
 398   assert( is_not_dead(n3), "can not use dead node");
 399   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 400   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 401   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 402   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 403 }
 404 
 405 //------------------------------Node-------------------------------------------
 406 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 407   : _idx(Init(5))
 408 #ifdef ASSERT
 409   , _parse_idx(_idx)
 410 #endif
 411 {
 412   debug_only( verify_construction() );
 413   NOT_PRODUCT(nodes_created++);
 414   assert( is_not_dead(n0), "can not use dead node");
 415   assert( is_not_dead(n1), "can not use dead node");
 416   assert( is_not_dead(n2), "can not use dead node");
 417   assert( is_not_dead(n3), "can not use dead node");
 418   assert( is_not_dead(n4), "can not use dead node");
 419   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 420   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 421   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 422   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 423   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 424 }
 425 
 426 //------------------------------Node-------------------------------------------
 427 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 428                      Node *n4, Node *n5)
 429   : _idx(Init(6))
 430 #ifdef ASSERT
 431   , _parse_idx(_idx)
 432 #endif
 433 {
 434   debug_only( verify_construction() );
 435   NOT_PRODUCT(nodes_created++);
 436   assert( is_not_dead(n0), "can not use dead node");
 437   assert( is_not_dead(n1), "can not use dead node");
 438   assert( is_not_dead(n2), "can not use dead node");
 439   assert( is_not_dead(n3), "can not use dead node");
 440   assert( is_not_dead(n4), "can not use dead node");
 441   assert( is_not_dead(n5), "can not use dead node");
 442   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 443   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 444   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 445   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 446   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 447   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 448 }
 449 
 450 //------------------------------Node-------------------------------------------
 451 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 452                      Node *n4, Node *n5, Node *n6)
 453   : _idx(Init(7))
 454 #ifdef ASSERT
 455   , _parse_idx(_idx)
 456 #endif
 457 {
 458   debug_only( verify_construction() );
 459   NOT_PRODUCT(nodes_created++);
 460   assert( is_not_dead(n0), "can not use dead node");
 461   assert( is_not_dead(n1), "can not use dead node");
 462   assert( is_not_dead(n2), "can not use dead node");
 463   assert( is_not_dead(n3), "can not use dead node");
 464   assert( is_not_dead(n4), "can not use dead node");
 465   assert( is_not_dead(n5), "can not use dead node");
 466   assert( is_not_dead(n6), "can not use dead node");
 467   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 468   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 469   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 470   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 471   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 472   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 473   _in[6] = n6; if (n6 != NULL) n6->add_out((Node *)this);
 474 }
 475 
 476 #ifdef __clang__
 477 #pragma clang diagnostic pop
 478 #endif
 479 
 480 
 481 //------------------------------clone------------------------------------------
 482 // Clone a Node.
 483 Node *Node::clone() const {
 484   Compile* C = Compile::current();
 485   uint s = size_of();           // Size of inherited Node
 486   Node *n = (Node*)C->node_arena()->Amalloc_D(size_of() + _max*sizeof(Node*));
 487   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 488   // Set the new input pointer array
 489   n->_in = (Node**)(((char*)n)+s);
 490   // Cannot share the old output pointer array, so kill it
 491   n->_out = NO_OUT_ARRAY;
 492   // And reset the counters to 0
 493   n->_outcnt = 0;
 494   n->_outmax = 0;
 495   // Unlock this guy, since he is not in any hash table.
 496   debug_only(n->_hash_lock = 0);
 497   // Walk the old node's input list to duplicate its edges
 498   uint i;
 499   for( i = 0; i < len(); i++ ) {
 500     Node *x = in(i);
 501     n->_in[i] = x;
 502     if (x != NULL) x->add_out(n);
 503   }
 504   if (is_macro())
 505     C->add_macro_node(n);
 506   if (is_expensive())
 507     C->add_expensive_node(n);
 508   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 509   bs->register_potential_barrier_node(n);
 510   // If the cloned node is a range check dependent CastII, add it to the list.
 511   CastIINode* cast = n->isa_CastII();
 512   if (cast != NULL && cast->has_range_check()) {
 513     C->add_range_check_cast(cast);
 514   }
 515   if (n->Opcode() == Op_Opaque4) {
 516     C->add_opaque4_node(n);
 517   }
 518 
 519   n->set_idx(C->next_unique()); // Get new unique index as well
 520   debug_only( n->verify_construction() );
 521   NOT_PRODUCT(nodes_created++);
 522   // Do not patch over the debug_idx of a clone, because it makes it
 523   // impossible to break on the clone's moment of creation.
 524   //debug_only( n->set_debug_idx( debug_idx() ) );
 525 
 526   C->copy_node_notes_to(n, (Node*) this);
 527 
 528   // MachNode clone
 529   uint nopnds;
 530   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 531     MachNode *mach  = n->as_Mach();
 532     MachNode *mthis = this->as_Mach();
 533     // Get address of _opnd_array.
 534     // It should be the same offset since it is the clone of this node.
 535     MachOper **from = mthis->_opnds;
 536     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 537                     pointer_delta((const void*)from,
 538                                   (const void*)(&mthis->_opnds), 1));
 539     mach->_opnds = to;
 540     for ( uint i = 0; i < nopnds; ++i ) {
 541       to[i] = from[i]->clone();
 542     }
 543   }
 544   // cloning CallNode may need to clone JVMState
 545   if (n->is_Call()) {
 546     n->as_Call()->clone_jvms(C);
 547   }
 548   if (n->is_SafePoint()) {
 549     n->as_SafePoint()->clone_replaced_nodes();
 550   }
 551   return n;                     // Return the clone
 552 }
 553 
 554 //---------------------------setup_is_top--------------------------------------
 555 // Call this when changing the top node, to reassert the invariants
 556 // required by Node::is_top.  See Compile::set_cached_top_node.
 557 void Node::setup_is_top() {
 558   if (this == (Node*)Compile::current()->top()) {
 559     // This node has just become top.  Kill its out array.
 560     _outcnt = _outmax = 0;
 561     _out = NULL;                           // marker value for top
 562     assert(is_top(), "must be top");
 563   } else {
 564     if (_out == NULL)  _out = NO_OUT_ARRAY;
 565     assert(!is_top(), "must not be top");
 566   }
 567 }
 568 
 569 
 570 //------------------------------~Node------------------------------------------
 571 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 572 void Node::destruct() {
 573   // Eagerly reclaim unique Node numberings
 574   Compile* compile = Compile::current();
 575   if ((uint)_idx+1 == compile->unique()) {
 576     compile->set_unique(compile->unique()-1);
 577   }
 578   // Clear debug info:
 579   Node_Notes* nn = compile->node_notes_at(_idx);
 580   if (nn != NULL)  nn->clear();
 581   // Walk the input array, freeing the corresponding output edges
 582   _cnt = _max;  // forget req/prec distinction
 583   uint i;
 584   for( i = 0; i < _max; i++ ) {
 585     set_req(i, NULL);
 586     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 587   }
 588   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 589   // See if the input array was allocated just prior to the object
 590   int edge_size = _max*sizeof(void*);
 591   int out_edge_size = _outmax*sizeof(void*);
 592   char *edge_end = ((char*)_in) + edge_size;
 593   char *out_array = (char*)(_out == NO_OUT_ARRAY? NULL: _out);
 594   int node_size = size_of();
 595 
 596   // Free the output edge array
 597   if (out_edge_size > 0) {
 598     compile->node_arena()->Afree(out_array, out_edge_size);
 599   }
 600 
 601   // Free the input edge array and the node itself
 602   if( edge_end == (char*)this ) {
 603     // It was; free the input array and object all in one hit
 604 #ifndef ASSERT
 605     compile->node_arena()->Afree(_in,edge_size+node_size);
 606 #endif
 607   } else {
 608     // Free just the input array
 609     compile->node_arena()->Afree(_in,edge_size);
 610 
 611     // Free just the object
 612 #ifndef ASSERT
 613     compile->node_arena()->Afree(this,node_size);
 614 #endif
 615   }
 616   if (is_macro()) {
 617     compile->remove_macro_node(this);
 618   }
 619   if (is_expensive()) {
 620     compile->remove_expensive_node(this);
 621   }
 622   CastIINode* cast = isa_CastII();
 623   if (cast != NULL && cast->has_range_check()) {
 624     compile->remove_range_check_cast(cast);
 625   }
 626   if (Opcode() == Op_Opaque4) {
 627     compile->remove_opaque4_node(this);
 628   }
 629 
 630   if (is_SafePoint()) {
 631     as_SafePoint()->delete_replaced_nodes();
 632   }
 633   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 634   bs->unregister_potential_barrier_node(this);
 635 #ifdef ASSERT
 636   // We will not actually delete the storage, but we'll make the node unusable.
 637   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 638   _in = _out = (Node**) badAddress;
 639   _max = _cnt = _outmax = _outcnt = 0;
 640   compile->remove_modified_node(this);
 641 #endif
 642 }
 643 
 644 //------------------------------grow-------------------------------------------
 645 // Grow the input array, making space for more edges
 646 void Node::grow( uint len ) {
 647   Arena* arena = Compile::current()->node_arena();
 648   uint new_max = _max;
 649   if( new_max == 0 ) {
 650     _max = 4;
 651     _in = (Node**)arena->Amalloc(4*sizeof(Node*));
 652     Node** to = _in;
 653     to[0] = NULL;
 654     to[1] = NULL;
 655     to[2] = NULL;
 656     to[3] = NULL;
 657     return;
 658   }
 659   while( new_max <= len ) new_max <<= 1; // Find next power-of-2
 660   // Trimming to limit allows a uint8 to handle up to 255 edges.
 661   // Previously I was using only powers-of-2 which peaked at 128 edges.
 662   //if( new_max >= limit ) new_max = limit-1;
 663   _in = (Node**)arena->Arealloc(_in, _max*sizeof(Node*), new_max*sizeof(Node*));
 664   Copy::zero_to_bytes(&_in[_max], (new_max-_max)*sizeof(Node*)); // NULL all new space
 665   _max = new_max;               // Record new max length
 666   // This assertion makes sure that Node::_max is wide enough to
 667   // represent the numerical value of new_max.
 668   assert(_max == new_max && _max > len, "int width of _max is too small");
 669 }
 670 
 671 //-----------------------------out_grow----------------------------------------
 672 // Grow the input array, making space for more edges
 673 void Node::out_grow( uint len ) {
 674   assert(!is_top(), "cannot grow a top node's out array");
 675   Arena* arena = Compile::current()->node_arena();
 676   uint new_max = _outmax;
 677   if( new_max == 0 ) {
 678     _outmax = 4;
 679     _out = (Node **)arena->Amalloc(4*sizeof(Node*));
 680     return;
 681   }
 682   while( new_max <= len ) new_max <<= 1; // Find next power-of-2
 683   // Trimming to limit allows a uint8 to handle up to 255 edges.
 684   // Previously I was using only powers-of-2 which peaked at 128 edges.
 685   //if( new_max >= limit ) new_max = limit-1;
 686   assert(_out != NULL && _out != NO_OUT_ARRAY, "out must have sensible value");
 687   _out = (Node**)arena->Arealloc(_out,_outmax*sizeof(Node*),new_max*sizeof(Node*));
 688   //Copy::zero_to_bytes(&_out[_outmax], (new_max-_outmax)*sizeof(Node*)); // NULL all new space
 689   _outmax = new_max;               // Record new max length
 690   // This assertion makes sure that Node::_max is wide enough to
 691   // represent the numerical value of new_max.
 692   assert(_outmax == new_max && _outmax > len, "int width of _outmax is too small");
 693 }
 694 
 695 #ifdef ASSERT
 696 //------------------------------is_dead----------------------------------------
 697 bool Node::is_dead() const {
 698   // Mach and pinch point nodes may look like dead.
 699   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 700     return false;
 701   for( uint i = 0; i < _max; i++ )
 702     if( _in[i] != NULL )
 703       return false;
 704   dump();
 705   return true;
 706 }
 707 #endif
 708 
 709 
 710 //------------------------------is_unreachable---------------------------------
 711 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 712   assert(!is_Mach(), "doesn't work with MachNodes");
 713   return outcnt() == 0 || igvn.type(this) == Type::TOP || (in(0) != NULL && in(0)->is_top());
 714 }
 715 
 716 //------------------------------add_req----------------------------------------
 717 // Add a new required input at the end
 718 void Node::add_req( Node *n ) {
 719   assert( is_not_dead(n), "can not use dead node");
 720 
 721   // Look to see if I can move precedence down one without reallocating
 722   if( (_cnt >= _max) || (in(_max-1) != NULL) )
 723     grow( _max+1 );
 724 
 725   // Find a precedence edge to move
 726   if( in(_cnt) != NULL ) {       // Next precedence edge is busy?
 727     uint i;
 728     for( i=_cnt; i<_max; i++ )
 729       if( in(i) == NULL )       // Find the NULL at end of prec edge list
 730         break;                  // There must be one, since we grew the array
 731     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 732   }
 733   _in[_cnt++] = n;            // Stuff over old prec edge
 734   if (n != NULL) n->add_out((Node *)this);
 735 }
 736 
 737 //---------------------------add_req_batch-------------------------------------
 738 // Add a new required input at the end
 739 void Node::add_req_batch( Node *n, uint m ) {
 740   assert( is_not_dead(n), "can not use dead node");
 741   // check various edge cases
 742   if ((int)m <= 1) {
 743     assert((int)m >= 0, "oob");
 744     if (m != 0)  add_req(n);
 745     return;
 746   }
 747 
 748   // Look to see if I can move precedence down one without reallocating
 749   if( (_cnt+m) > _max || _in[_max-m] )
 750     grow( _max+m );
 751 
 752   // Find a precedence edge to move
 753   if( _in[_cnt] != NULL ) {     // Next precedence edge is busy?
 754     uint i;
 755     for( i=_cnt; i<_max; i++ )
 756       if( _in[i] == NULL )      // Find the NULL at end of prec edge list
 757         break;                  // There must be one, since we grew the array
 758     // Slide all the precs over by m positions (assume #prec << m).
 759     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 760   }
 761 
 762   // Stuff over the old prec edges
 763   for(uint i=0; i<m; i++ ) {
 764     _in[_cnt++] = n;
 765   }
 766 
 767   // Insert multiple out edges on the node.
 768   if (n != NULL && !n->is_top()) {
 769     for(uint i=0; i<m; i++ ) {
 770       n->add_out((Node *)this);
 771     }
 772   }
 773 }
 774 
 775 //------------------------------del_req----------------------------------------
 776 // Delete the required edge and compact the edge array
 777 void Node::del_req( uint idx ) {
 778   assert( idx < _cnt, "oob");
 779   assert( !VerifyHashTableKeys || _hash_lock == 0,
 780           "remove node from hash table before modifying it");
 781   // First remove corresponding def-use edge
 782   Node *n = in(idx);
 783   if (n != NULL) n->del_out((Node *)this);
 784   _in[idx] = in(--_cnt); // Compact the array
 785   // Avoid spec violation: Gap in prec edges.
 786   close_prec_gap_at(_cnt);
 787   Compile::current()->record_modified_node(this);
 788 }
 789 
 790 //------------------------------del_req_ordered--------------------------------
 791 // Delete the required edge and compact the edge array with preserved order
 792 void Node::del_req_ordered( uint idx ) {
 793   assert( idx < _cnt, "oob");
 794   assert( !VerifyHashTableKeys || _hash_lock == 0,
 795           "remove node from hash table before modifying it");
 796   // First remove corresponding def-use edge
 797   Node *n = in(idx);
 798   if (n != NULL) n->del_out((Node *)this);
 799   if (idx < --_cnt) {    // Not last edge ?
 800     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
 801   }
 802   // Avoid spec violation: Gap in prec edges.
 803   close_prec_gap_at(_cnt);
 804   Compile::current()->record_modified_node(this);
 805 }
 806 
 807 //------------------------------ins_req----------------------------------------
 808 // Insert a new required input at the end
 809 void Node::ins_req( uint idx, Node *n ) {
 810   assert( is_not_dead(n), "can not use dead node");
 811   add_req(NULL);                // Make space
 812   assert( idx < _max, "Must have allocated enough space");
 813   // Slide over
 814   if(_cnt-idx-1 > 0) {
 815     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 816   }
 817   _in[idx] = n;                            // Stuff over old required edge
 818   if (n != NULL) n->add_out((Node *)this); // Add reciprocal def-use edge
 819 }
 820 
 821 //-----------------------------find_edge---------------------------------------
 822 int Node::find_edge(Node* n) {
 823   for (uint i = 0; i < len(); i++) {
 824     if (_in[i] == n)  return i;
 825   }
 826   return -1;
 827 }
 828 
 829 //----------------------------replace_edge-------------------------------------
 830 int Node::replace_edge(Node* old, Node* neww) {
 831   if (old == neww)  return 0;  // nothing to do
 832   uint nrep = 0;
 833   for (uint i = 0; i < len(); i++) {
 834     if (in(i) == old) {
 835       if (i < req()) {
 836         set_req(i, neww);
 837       } else {
 838         assert(find_prec_edge(neww) == -1, "spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx);
 839         set_prec(i, neww);
 840       }
 841       nrep++;
 842     }
 843   }
 844   return nrep;
 845 }
 846 
 847 /**
 848  * Replace input edges in the range pointing to 'old' node.
 849  */
 850 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end) {
 851   if (old == neww)  return 0;  // nothing to do
 852   uint nrep = 0;
 853   for (int i = start; i < end; i++) {
 854     if (in(i) == old) {
 855       set_req(i, neww);
 856       nrep++;
 857     }
 858   }
 859   return nrep;
 860 }
 861 
 862 //-------------------------disconnect_inputs-----------------------------------
 863 // NULL out all inputs to eliminate incoming Def-Use edges.
 864 // Return the number of edges between 'n' and 'this'
 865 int Node::disconnect_inputs(Node *n, Compile* C) {
 866   int edges_to_n = 0;
 867 
 868   uint cnt = req();
 869   for( uint i = 0; i < cnt; ++i ) {
 870     if( in(i) == 0 ) continue;
 871     if( in(i) == n ) ++edges_to_n;
 872     set_req(i, NULL);
 873   }
 874   // Remove precedence edges if any exist
 875   // Note: Safepoints may have precedence edges, even during parsing
 876   if( (req() != len()) && (in(req()) != NULL) ) {
 877     uint max = len();
 878     for( uint i = 0; i < max; ++i ) {
 879       if( in(i) == 0 ) continue;
 880       if( in(i) == n ) ++edges_to_n;
 881       set_prec(i, NULL);
 882     }
 883   }
 884 
 885   // Node::destruct requires all out edges be deleted first
 886   // debug_only(destruct();)   // no reuse benefit expected
 887   if (edges_to_n == 0) {
 888     C->record_dead_node(_idx);
 889   }
 890   return edges_to_n;
 891 }
 892 
 893 //-----------------------------uncast---------------------------------------
 894 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 895 // Strip away casting.  (It is depth-limited.)
 896 Node* Node::uncast() const {
 897   // Should be inline:
 898   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 899   if (is_ConstraintCast())
 900     return uncast_helper(this);
 901   else
 902     return (Node*) this;
 903 }
 904 
 905 // Find out of current node that matches opcode.
 906 Node* Node::find_out_with(int opcode) {
 907   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 908     Node* use = fast_out(i);
 909     if (use->Opcode() == opcode) {
 910       return use;
 911     }
 912   }
 913   return NULL;
 914 }
 915 
 916 // Return true if the current node has an out that matches opcode.
 917 bool Node::has_out_with(int opcode) {
 918   return (find_out_with(opcode) != NULL);
 919 }
 920 
 921 // Return true if the current node has an out that matches any of the opcodes.
 922 bool Node::has_out_with(int opcode1, int opcode2, int opcode3, int opcode4) {
 923   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 924       int opcode = fast_out(i)->Opcode();
 925       if (opcode == opcode1 || opcode == opcode2 || opcode == opcode3 || opcode == opcode4) {
 926         return true;
 927       }
 928   }
 929   return false;
 930 }
 931 
 932 
 933 //---------------------------uncast_helper-------------------------------------
 934 Node* Node::uncast_helper(const Node* p) {
 935 #ifdef ASSERT
 936   uint depth_count = 0;
 937   const Node* orig_p = p;
 938 #endif
 939 
 940   while (true) {
 941 #ifdef ASSERT
 942     if (depth_count >= K) {
 943       orig_p->dump(4);
 944       if (p != orig_p)
 945         p->dump(1);
 946     }
 947     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
 948 #endif
 949     if (p == NULL || p->req() != 2) {
 950       break;
 951     } else if (p->is_ConstraintCast()) {
 952       p = p->in(1);
 953     } else {
 954       break;
 955     }
 956   }
 957   return (Node*) p;
 958 }
 959 
 960 //------------------------------add_prec---------------------------------------
 961 // Add a new precedence input.  Precedence inputs are unordered, with
 962 // duplicates removed and NULLs packed down at the end.
 963 void Node::add_prec( Node *n ) {
 964   assert( is_not_dead(n), "can not use dead node");
 965 
 966   // Check for NULL at end
 967   if( _cnt >= _max || in(_max-1) )
 968     grow( _max+1 );
 969 
 970   // Find a precedence edge to move
 971   uint i = _cnt;
 972   while( in(i) != NULL ) {
 973     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
 974     i++;
 975   }
 976   _in[i] = n;                                // Stuff prec edge over NULL
 977   if ( n != NULL) n->add_out((Node *)this);  // Add mirror edge
 978 
 979 #ifdef ASSERT
 980   while ((++i)<_max) { assert(_in[i] == NULL, "spec violation: Gap in prec edges (node %d)", _idx); }
 981 #endif
 982 }
 983 
 984 //------------------------------rm_prec----------------------------------------
 985 // Remove a precedence input.  Precedence inputs are unordered, with
 986 // duplicates removed and NULLs packed down at the end.
 987 void Node::rm_prec( uint j ) {
 988   assert(j < _max, "oob: i=%d, _max=%d", j, _max);
 989   assert(j >= _cnt, "not a precedence edge");
 990   if (_in[j] == NULL) return;   // Avoid spec violation: Gap in prec edges.
 991   _in[j]->del_out((Node *)this);
 992   close_prec_gap_at(j);
 993 }
 994 
 995 //------------------------------size_of----------------------------------------
 996 uint Node::size_of() const { return sizeof(*this); }
 997 
 998 //------------------------------ideal_reg--------------------------------------
 999 uint Node::ideal_reg() const { return 0; }
1000 
1001 //------------------------------jvms-------------------------------------------
1002 JVMState* Node::jvms() const { return NULL; }
1003 
1004 #ifdef ASSERT
1005 //------------------------------jvms-------------------------------------------
1006 bool Node::verify_jvms(const JVMState* using_jvms) const {
1007   for (JVMState* jvms = this->jvms(); jvms != NULL; jvms = jvms->caller()) {
1008     if (jvms == using_jvms)  return true;
1009   }
1010   return false;
1011 }
1012 
1013 //------------------------------init_NodeProperty------------------------------
1014 void Node::init_NodeProperty() {
1015   assert(_max_classes <= max_jushort, "too many NodeProperty classes");
1016   assert(_max_flags <= max_jushort, "too many NodeProperty flags");
1017 }
1018 #endif
1019 
1020 //------------------------------format-----------------------------------------
1021 // Print as assembly
1022 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1023 //------------------------------emit-------------------------------------------
1024 // Emit bytes starting at parameter 'ptr'.
1025 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
1026 //------------------------------size-------------------------------------------
1027 // Size of instruction in bytes
1028 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1029 
1030 //------------------------------CFG Construction-------------------------------
1031 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1032 // Goto and Return.
1033 const Node *Node::is_block_proj() const { return 0; }
1034 
1035 // Minimum guaranteed type
1036 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1037 
1038 
1039 //------------------------------raise_bottom_type------------------------------
1040 // Get the worst-case Type output for this Node.
1041 void Node::raise_bottom_type(const Type* new_type) {
1042   if (is_Type()) {
1043     TypeNode *n = this->as_Type();
1044     if (VerifyAliases) {
1045       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1046     }
1047     n->set_type(new_type);
1048   } else if (is_Load()) {
1049     LoadNode *n = this->as_Load();
1050     if (VerifyAliases) {
1051       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1052     }
1053     n->set_type(new_type);
1054   }
1055 }
1056 
1057 //------------------------------Identity---------------------------------------
1058 // Return a node that the given node is equivalent to.
1059 Node* Node::Identity(PhaseGVN* phase) {
1060   return this;                  // Default to no identities
1061 }
1062 
1063 //------------------------------Value------------------------------------------
1064 // Compute a new Type for a node using the Type of the inputs.
1065 const Type* Node::Value(PhaseGVN* phase) const {
1066   return bottom_type();         // Default to worst-case Type
1067 }
1068 
1069 //------------------------------Ideal------------------------------------------
1070 //
1071 // 'Idealize' the graph rooted at this Node.
1072 //
1073 // In order to be efficient and flexible there are some subtle invariants
1074 // these Ideal calls need to hold.  Running with '+VerifyIterativeGVN' checks
1075 // these invariants, although its too slow to have on by default.  If you are
1076 // hacking an Ideal call, be sure to test with +VerifyIterativeGVN!
1077 //
1078 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1079 // pointer.  If ANY change is made, it must return the root of the reshaped
1080 // graph - even if the root is the same Node.  Example: swapping the inputs
1081 // to an AddINode gives the same answer and same root, but you still have to
1082 // return the 'this' pointer instead of NULL.
1083 //
1084 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1085 // Identity call to return an old Node; basically if Identity can find
1086 // another Node have the Ideal call make no change and return NULL.
1087 // Example: AddINode::Ideal must check for add of zero; in this case it
1088 // returns NULL instead of doing any graph reshaping.
1089 //
1090 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1091 // sharing there may be other users of the old Nodes relying on their current
1092 // semantics.  Modifying them will break the other users.
1093 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1094 // "X+3" unchanged in case it is shared.
1095 //
1096 // If you modify the 'this' pointer's inputs, you should use
1097 // 'set_req'.  If you are making a new Node (either as the new root or
1098 // some new internal piece) you may use 'init_req' to set the initial
1099 // value.  You can make a new Node with either 'new' or 'clone'.  In
1100 // either case, def-use info is correctly maintained.
1101 //
1102 // Example: reshape "(X+3)+4" into "X+7":
1103 //    set_req(1, in(1)->in(1));
1104 //    set_req(2, phase->intcon(7));
1105 //    return this;
1106 // Example: reshape "X*4" into "X<<2"
1107 //    return new LShiftINode(in(1), phase->intcon(2));
1108 //
1109 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1110 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1111 //    Node *shift=phase->transform(new LShiftINode(in(1),phase->intcon(5)));
1112 //    return new AddINode(shift, in(1));
1113 //
1114 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1115 // These forms are faster than 'phase->transform(new ConNode())' and Do
1116 // The Right Thing with def-use info.
1117 //
1118 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1119 // graph uses the 'this' Node it must be the root.  If you want a Node with
1120 // the same Opcode as the 'this' pointer use 'clone'.
1121 //
1122 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1123   return NULL;                  // Default to being Ideal already
1124 }
1125 
1126 // Some nodes have specific Ideal subgraph transformations only if they are
1127 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1128 // for the transformations to happen.
1129 bool Node::has_special_unique_user() const {
1130   assert(outcnt() == 1, "match only for unique out");
1131   Node* n = unique_out();
1132   int op  = Opcode();
1133   if (this->is_Store()) {
1134     // Condition for back-to-back stores folding.
1135     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1136   } else if (this->is_Load() || this->is_DecodeN() || this->is_Phi()) {
1137     // Condition for removing an unused LoadNode or DecodeNNode from the MemBarAcquire precedence input
1138     return n->Opcode() == Op_MemBarAcquire;
1139   } else if (op == Op_AddL) {
1140     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1141     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1142   } else if (op == Op_SubI || op == Op_SubL) {
1143     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1144     return n->Opcode() == op && n->in(2) == this;
1145   } else if (is_If() && (n->is_IfFalse() || n->is_IfTrue())) {
1146     // See IfProjNode::Identity()
1147     return true;
1148 #if INCLUDE_SHENANDOAHGC
1149   } else if (op == Op_ShenandoahWriteBarrier) {
1150     return n->Opcode() == Op_ShenandoahWBMemProj;
1151 #endif
1152   }
1153   return false;
1154 };
1155 
1156 //--------------------------find_exact_control---------------------------------
1157 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1158 Node* Node::find_exact_control(Node* ctrl) {
1159   if (ctrl == NULL && this->is_Region())
1160     ctrl = this->as_Region()->is_copy();
1161 
1162   if (ctrl != NULL && ctrl->is_CatchProj()) {
1163     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1164       ctrl = ctrl->in(0);
1165     if (ctrl != NULL && !ctrl->is_top())
1166       ctrl = ctrl->in(0);
1167   }
1168 
1169   if (ctrl != NULL && ctrl->is_Proj())
1170     ctrl = ctrl->in(0);
1171 
1172   return ctrl;
1173 }
1174 
1175 //--------------------------dominates------------------------------------------
1176 // Helper function for MemNode::all_controls_dominate().
1177 // Check if 'this' control node dominates or equal to 'sub' control node.
1178 // We already know that if any path back to Root or Start reaches 'this',
1179 // then all paths so, so this is a simple search for one example,
1180 // not an exhaustive search for a counterexample.
1181 bool Node::dominates(Node* sub, Node_List &nlist) {
1182   assert(this->is_CFG(), "expecting control");
1183   assert(sub != NULL && sub->is_CFG(), "expecting control");
1184 
1185   // detect dead cycle without regions
1186   int iterations_without_region_limit = DominatorSearchLimit;
1187 
1188   Node* orig_sub = sub;
1189   Node* dom      = this;
1190   bool  met_dom  = false;
1191   nlist.clear();
1192 
1193   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1194   // After seeing 'dom', continue up to Root or Start.
1195   // If we hit a region (backward split point), it may be a loop head.
1196   // Keep going through one of the region's inputs.  If we reach the
1197   // same region again, go through a different input.  Eventually we
1198   // will either exit through the loop head, or give up.
1199   // (If we get confused, break out and return a conservative 'false'.)
1200   while (sub != NULL) {
1201     if (sub->is_top())  break; // Conservative answer for dead code.
1202     if (sub == dom) {
1203       if (nlist.size() == 0) {
1204         // No Region nodes except loops were visited before and the EntryControl
1205         // path was taken for loops: it did not walk in a cycle.
1206         return true;
1207       } else if (met_dom) {
1208         break;          // already met before: walk in a cycle
1209       } else {
1210         // Region nodes were visited. Continue walk up to Start or Root
1211         // to make sure that it did not walk in a cycle.
1212         met_dom = true; // first time meet
1213         iterations_without_region_limit = DominatorSearchLimit; // Reset
1214      }
1215     }
1216     if (sub->is_Start() || sub->is_Root()) {
1217       // Success if we met 'dom' along a path to Start or Root.
1218       // We assume there are no alternative paths that avoid 'dom'.
1219       // (This assumption is up to the caller to ensure!)
1220       return met_dom;
1221     }
1222     Node* up = sub->in(0);
1223     // Normalize simple pass-through regions and projections:
1224     up = sub->find_exact_control(up);
1225     // If sub == up, we found a self-loop.  Try to push past it.
1226     if (sub == up && sub->is_Loop()) {
1227       // Take loop entry path on the way up to 'dom'.
1228       up = sub->in(1); // in(LoopNode::EntryControl);
1229     } else if (sub == up && sub->is_Region() && sub->req() != 3) {
1230       // Always take in(1) path on the way up to 'dom' for clone regions
1231       // (with only one input) or regions which merge > 2 paths
1232       // (usually used to merge fast/slow paths).
1233       up = sub->in(1);
1234     } else if (sub == up && sub->is_Region()) {
1235       // Try both paths for Regions with 2 input paths (it may be a loop head).
1236       // It could give conservative 'false' answer without information
1237       // which region's input is the entry path.
1238       iterations_without_region_limit = DominatorSearchLimit; // Reset
1239 
1240       bool region_was_visited_before = false;
1241       // Was this Region node visited before?
1242       // If so, we have reached it because we accidentally took a
1243       // loop-back edge from 'sub' back into the body of the loop,
1244       // and worked our way up again to the loop header 'sub'.
1245       // So, take the first unexplored path on the way up to 'dom'.
1246       for (int j = nlist.size() - 1; j >= 0; j--) {
1247         intptr_t ni = (intptr_t)nlist.at(j);
1248         Node* visited = (Node*)(ni & ~1);
1249         bool  visited_twice_already = ((ni & 1) != 0);
1250         if (visited == sub) {
1251           if (visited_twice_already) {
1252             // Visited 2 paths, but still stuck in loop body.  Give up.
1253             return false;
1254           }
1255           // The Region node was visited before only once.
1256           // (We will repush with the low bit set, below.)
1257           nlist.remove(j);
1258           // We will find a new edge and re-insert.
1259           region_was_visited_before = true;
1260           break;
1261         }
1262       }
1263 
1264       // Find an incoming edge which has not been seen yet; walk through it.
1265       assert(up == sub, "");
1266       uint skip = region_was_visited_before ? 1 : 0;
1267       for (uint i = 1; i < sub->req(); i++) {
1268         Node* in = sub->in(i);
1269         if (in != NULL && !in->is_top() && in != sub) {
1270           if (skip == 0) {
1271             up = in;
1272             break;
1273           }
1274           --skip;               // skip this nontrivial input
1275         }
1276       }
1277 
1278       // Set 0 bit to indicate that both paths were taken.
1279       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1280     }
1281 
1282     if (up == sub) {
1283       break;    // some kind of tight cycle
1284     }
1285     if (up == orig_sub && met_dom) {
1286       // returned back after visiting 'dom'
1287       break;    // some kind of cycle
1288     }
1289     if (--iterations_without_region_limit < 0) {
1290       break;    // dead cycle
1291     }
1292     sub = up;
1293   }
1294 
1295   // Did not meet Root or Start node in pred. chain.
1296   // Conservative answer for dead code.
1297   return false;
1298 }
1299 
1300 //------------------------------remove_dead_region-----------------------------
1301 // This control node is dead.  Follow the subgraph below it making everything
1302 // using it dead as well.  This will happen normally via the usual IterGVN
1303 // worklist but this call is more efficient.  Do not update use-def info
1304 // inside the dead region, just at the borders.
1305 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1306   // Con's are a popular node to re-hit in the hash table again.
1307   if( dead->is_Con() ) return;
1308 
1309   // Can't put ResourceMark here since igvn->_worklist uses the same arena
1310   // for verify pass with +VerifyOpto and we add/remove elements in it here.
1311   Node_List  nstack(Thread::current()->resource_area());
1312 
1313   Node *top = igvn->C->top();
1314   nstack.push(dead);
1315   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1316 
1317   while (nstack.size() > 0) {
1318     dead = nstack.pop();
1319     if (dead->outcnt() > 0) {
1320       // Keep dead node on stack until all uses are processed.
1321       nstack.push(dead);
1322       // For all Users of the Dead...    ;-)
1323       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1324         Node* use = dead->last_out(k);
1325         igvn->hash_delete(use);       // Yank from hash table prior to mod
1326         if (use->in(0) == dead) {     // Found another dead node
1327           assert (!use->is_Con(), "Control for Con node should be Root node.");
1328           use->set_req(0, top);       // Cut dead edge to prevent processing
1329           nstack.push(use);           // the dead node again.
1330         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1331                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1332                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1333           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1334           use->set_req(0, top);       // Cut self edge
1335           nstack.push(use);
1336         } else {                      // Else found a not-dead user
1337           // Dead if all inputs are top or null
1338           bool dead_use = !use->is_Root(); // Keep empty graph alive
1339           for (uint j = 1; j < use->req(); j++) {
1340             Node* in = use->in(j);
1341             if (in == dead) {         // Turn all dead inputs into TOP
1342               use->set_req(j, top);
1343             } else if (in != NULL && !in->is_top()) {
1344               dead_use = false;
1345             }
1346           }
1347           if (dead_use) {
1348             if (use->is_Region()) {
1349               use->set_req(0, top);   // Cut self edge
1350             }
1351             nstack.push(use);
1352           } else {
1353             igvn->_worklist.push(use);
1354           }
1355         }
1356         // Refresh the iterator, since any number of kills might have happened.
1357         k = dead->last_outs(kmin);
1358       }
1359     } else { // (dead->outcnt() == 0)
1360       // Done with outputs.
1361       igvn->hash_delete(dead);
1362       igvn->_worklist.remove(dead);
1363       igvn->C->remove_modified_node(dead);
1364       igvn->set_type(dead, Type::TOP);
1365       if (dead->is_macro()) {
1366         igvn->C->remove_macro_node(dead);
1367       }
1368       if (dead->is_expensive()) {
1369         igvn->C->remove_expensive_node(dead);
1370       }
1371       CastIINode* cast = dead->isa_CastII();
1372       if (cast != NULL && cast->has_range_check()) {
1373         igvn->C->remove_range_check_cast(cast);
1374       }
1375       if (dead->Opcode() == Op_Opaque4) {
1376         igvn->C->remove_opaque4_node(dead);
1377       }
1378       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1379       bs->unregister_potential_barrier_node(dead);
1380       igvn->C->record_dead_node(dead->_idx);
1381       // Kill all inputs to the dead guy
1382       for (uint i=0; i < dead->req(); i++) {
1383         Node *n = dead->in(i);      // Get input to dead guy
1384         if (n != NULL && !n->is_top()) { // Input is valid?
1385           dead->set_req(i, top);    // Smash input away
1386           if (n->outcnt() == 0) {   // Input also goes dead?
1387             if (!n->is_Con())
1388               nstack.push(n);       // Clear it out as well
1389           } else if (n->outcnt() == 1 &&
1390                      n->has_special_unique_user()) {
1391             igvn->add_users_to_worklist( n );
1392           } else if (n->outcnt() <= 2 && n->is_Store()) {
1393             // Push store's uses on worklist to enable folding optimization for
1394             // store/store and store/load to the same address.
1395             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1396             // and remove_globally_dead_node().
1397             igvn->add_users_to_worklist( n );
1398 #if INCLUDE_SHENANDOAHGC
1399           // TODO: Move into below enqueue_useful_gc_barrier() call
1400           } else if (n->Opcode() == Op_AddP && ShenandoahBarrierSetC2::has_only_shenandoah_wb_pre_uses(n)) {
1401             igvn->add_users_to_worklist(n);
1402 #endif
1403           } else {
1404             BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn->_worklist, n);
1405           }
1406         }
1407       }
1408     } // (dead->outcnt() == 0)
1409   }   // while (nstack.size() > 0) for outputs
1410   return;
1411 }
1412 
1413 //------------------------------remove_dead_region-----------------------------
1414 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1415   Node *n = in(0);
1416   if( !n ) return false;
1417   // Lost control into this guy?  I.e., it became unreachable?
1418   // Aggressively kill all unreachable code.
1419   if (can_reshape && n->is_top()) {
1420     kill_dead_code(this, phase->is_IterGVN());
1421     return false; // Node is dead.
1422   }
1423 
1424   if( n->is_Region() && n->as_Region()->is_copy() ) {
1425     Node *m = n->nonnull_req();
1426     set_req(0, m);
1427     return true;
1428   }
1429   return false;
1430 }
1431 
1432 //------------------------------hash-------------------------------------------
1433 // Hash function over Nodes.
1434 uint Node::hash() const {
1435   uint sum = 0;
1436   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1437     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded NULLs
1438   return (sum>>2) + _cnt + Opcode();
1439 }
1440 
1441 //------------------------------cmp--------------------------------------------
1442 // Compare special parts of simple Nodes
1443 uint Node::cmp( const Node &n ) const {
1444   return 1;                     // Must be same
1445 }
1446 
1447 //------------------------------rematerialize-----------------------------------
1448 // Should we clone rather than spill this instruction?
1449 bool Node::rematerialize() const {
1450   if ( is_Mach() )
1451     return this->as_Mach()->rematerialize();
1452   else
1453     return (_flags & Flag_rematerialize) != 0;
1454 }
1455 
1456 //------------------------------needs_anti_dependence_check---------------------
1457 // Nodes which use memory without consuming it, hence need antidependences.
1458 bool Node::needs_anti_dependence_check() const {
1459   if( req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0 )
1460     return false;
1461   else
1462     return in(1)->bottom_type()->has_memory();
1463 }
1464 
1465 
1466 // Get an integer constant from a ConNode (or CastIINode).
1467 // Return a default value if there is no apparent constant here.
1468 const TypeInt* Node::find_int_type() const {
1469   if (this->is_Type()) {
1470     return this->as_Type()->type()->isa_int();
1471   } else if (this->is_Con()) {
1472     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1473     return this->bottom_type()->isa_int();
1474   }
1475   return NULL;
1476 }
1477 
1478 // Get a pointer constant from a ConstNode.
1479 // Returns the constant if it is a pointer ConstNode
1480 intptr_t Node::get_ptr() const {
1481   assert( Opcode() == Op_ConP, "" );
1482   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1483 }
1484 
1485 // Get a narrow oop constant from a ConNNode.
1486 intptr_t Node::get_narrowcon() const {
1487   assert( Opcode() == Op_ConN, "" );
1488   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1489 }
1490 
1491 // Get a long constant from a ConNode.
1492 // Return a default value if there is no apparent constant here.
1493 const TypeLong* Node::find_long_type() const {
1494   if (this->is_Type()) {
1495     return this->as_Type()->type()->isa_long();
1496   } else if (this->is_Con()) {
1497     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1498     return this->bottom_type()->isa_long();
1499   }
1500   return NULL;
1501 }
1502 
1503 
1504 /**
1505  * Return a ptr type for nodes which should have it.
1506  */
1507 const TypePtr* Node::get_ptr_type() const {
1508   const TypePtr* tp = this->bottom_type()->make_ptr();
1509 #ifdef ASSERT
1510   if (tp == NULL) {
1511     this->dump(1);
1512     assert((tp != NULL), "unexpected node type");
1513   }
1514 #endif
1515   return tp;
1516 }
1517 
1518 // Get a double constant from a ConstNode.
1519 // Returns the constant if it is a double ConstNode
1520 jdouble Node::getd() const {
1521   assert( Opcode() == Op_ConD, "" );
1522   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1523 }
1524 
1525 // Get a float constant from a ConstNode.
1526 // Returns the constant if it is a float ConstNode
1527 jfloat Node::getf() const {
1528   assert( Opcode() == Op_ConF, "" );
1529   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1530 }
1531 
1532 #ifndef PRODUCT
1533 
1534 //------------------------------find------------------------------------------
1535 // Find a neighbor of this Node with the given _idx
1536 // If idx is negative, find its absolute value, following both _in and _out.
1537 static void find_recur(Compile* C,  Node* &result, Node *n, int idx, bool only_ctrl,
1538                         VectorSet* old_space, VectorSet* new_space ) {
1539   int node_idx = (idx >= 0) ? idx : -idx;
1540   if (NotANode(n))  return;  // Gracefully handle NULL, -1, 0xabababab, etc.
1541   // Contained in new_space or old_space?   Check old_arena first since it's mostly empty.
1542   VectorSet *v = C->old_arena()->contains(n) ? old_space : new_space;
1543   if( v->test(n->_idx) ) return;
1544   if( (int)n->_idx == node_idx
1545       debug_only(|| n->debug_idx() == node_idx) ) {
1546     if (result != NULL)
1547       tty->print("find: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1548                  (uintptr_t)result, (uintptr_t)n, node_idx);
1549     result = n;
1550   }
1551   v->set(n->_idx);
1552   for( uint i=0; i<n->len(); i++ ) {
1553     if( only_ctrl && !(n->is_Region()) && (n->Opcode() != Op_Root) && (i != TypeFunc::Control) ) continue;
1554     find_recur(C, result, n->in(i), idx, only_ctrl, old_space, new_space );
1555   }
1556   // Search along forward edges also:
1557   if (idx < 0 && !only_ctrl) {
1558     for( uint j=0; j<n->outcnt(); j++ ) {
1559       find_recur(C, result, n->raw_out(j), idx, only_ctrl, old_space, new_space );
1560     }
1561   }
1562 #ifdef ASSERT
1563   // Search along debug_orig edges last, checking for cycles
1564   Node* orig = n->debug_orig();
1565   if (orig != NULL) {
1566     do {
1567       if (NotANode(orig))  break;
1568       find_recur(C, result, orig, idx, only_ctrl, old_space, new_space );
1569       orig = orig->debug_orig();
1570     } while (orig != NULL && orig != n->debug_orig());
1571   }
1572 #endif //ASSERT
1573 }
1574 
1575 // call this from debugger:
1576 Node* find_node(Node* n, int idx) {
1577   return n->find(idx);
1578 }
1579 
1580 //------------------------------find-------------------------------------------
1581 Node* Node::find(int idx) const {
1582   ResourceArea *area = Thread::current()->resource_area();
1583   VectorSet old_space(area), new_space(area);
1584   Node* result = NULL;
1585   find_recur(Compile::current(), result, (Node*) this, idx, false, &old_space, &new_space );
1586   return result;
1587 }
1588 
1589 //------------------------------find_ctrl--------------------------------------
1590 // Find an ancestor to this node in the control history with given _idx
1591 Node* Node::find_ctrl(int idx) const {
1592   ResourceArea *area = Thread::current()->resource_area();
1593   VectorSet old_space(area), new_space(area);
1594   Node* result = NULL;
1595   find_recur(Compile::current(), result, (Node*) this, idx, true, &old_space, &new_space );
1596   return result;
1597 }
1598 #endif
1599 
1600 
1601 
1602 #ifndef PRODUCT
1603 
1604 // -----------------------------Name-------------------------------------------
1605 extern const char *NodeClassNames[];
1606 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
1607 
1608 static bool is_disconnected(const Node* n) {
1609   for (uint i = 0; i < n->req(); i++) {
1610     if (n->in(i) != NULL)  return false;
1611   }
1612   return true;
1613 }
1614 
1615 #ifdef ASSERT
1616 static void dump_orig(Node* orig, outputStream *st) {
1617   Compile* C = Compile::current();
1618   if (NotANode(orig)) orig = NULL;
1619   if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1620   if (orig == NULL) return;
1621   st->print(" !orig=");
1622   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
1623   if (NotANode(fast)) fast = NULL;
1624   while (orig != NULL) {
1625     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
1626     if (discon) st->print("[");
1627     if (!Compile::current()->node_arena()->contains(orig))
1628       st->print("o");
1629     st->print("%d", orig->_idx);
1630     if (discon) st->print("]");
1631     orig = orig->debug_orig();
1632     if (NotANode(orig)) orig = NULL;
1633     if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1634     if (orig != NULL) st->print(",");
1635     if (fast != NULL) {
1636       // Step fast twice for each single step of orig:
1637       fast = fast->debug_orig();
1638       if (NotANode(fast)) fast = NULL;
1639       if (fast != NULL && fast != orig) {
1640         fast = fast->debug_orig();
1641         if (NotANode(fast)) fast = NULL;
1642       }
1643       if (fast == orig) {
1644         st->print("...");
1645         break;
1646       }
1647     }
1648   }
1649 }
1650 
1651 void Node::set_debug_orig(Node* orig) {
1652   _debug_orig = orig;
1653   if (BreakAtNode == 0)  return;
1654   if (NotANode(orig))  orig = NULL;
1655   int trip = 10;
1656   while (orig != NULL) {
1657     if (orig->debug_idx() == BreakAtNode || (int)orig->_idx == BreakAtNode) {
1658       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d orig._idx=%d orig._debug_idx=%d",
1659                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
1660       BREAKPOINT;
1661     }
1662     orig = orig->debug_orig();
1663     if (NotANode(orig))  orig = NULL;
1664     if (trip-- <= 0)  break;
1665   }
1666 }
1667 #endif //ASSERT
1668 
1669 //------------------------------dump------------------------------------------
1670 // Dump a Node
1671 void Node::dump(const char* suffix, bool mark, outputStream *st) const {
1672   Compile* C = Compile::current();
1673   bool is_new = C->node_arena()->contains(this);
1674   C->_in_dump_cnt++;
1675   st->print("%c%d%s\t%s\t=== ", is_new ? ' ' : 'o', _idx, mark ? " >" : "", Name());
1676 
1677   // Dump the required and precedence inputs
1678   dump_req(st);
1679   dump_prec(st);
1680   // Dump the outputs
1681   dump_out(st);
1682 
1683   if (is_disconnected(this)) {
1684 #ifdef ASSERT
1685     st->print("  [%d]",debug_idx());
1686     dump_orig(debug_orig(), st);
1687 #endif
1688     st->cr();
1689     C->_in_dump_cnt--;
1690     return;                     // don't process dead nodes
1691   }
1692 
1693   if (C->clone_map().value(_idx) != 0) {
1694     C->clone_map().dump(_idx);
1695   }
1696   // Dump node-specific info
1697   dump_spec(st);
1698 #ifdef ASSERT
1699   // Dump the non-reset _debug_idx
1700   if (Verbose && WizardMode) {
1701     st->print("  [%d]",debug_idx());
1702   }
1703 #endif
1704 
1705   const Type *t = bottom_type();
1706 
1707   if (t != NULL && (t->isa_instptr() || t->isa_klassptr())) {
1708     const TypeInstPtr  *toop = t->isa_instptr();
1709     const TypeKlassPtr *tkls = t->isa_klassptr();
1710     ciKlass*           klass = toop ? toop->klass() : (tkls ? tkls->klass() : NULL );
1711     if (klass && klass->is_loaded() && klass->is_interface()) {
1712       st->print("  Interface:");
1713     } else if (toop) {
1714       st->print("  Oop:");
1715     } else if (tkls) {
1716       st->print("  Klass:");
1717     }
1718     t->dump_on(st);
1719   } else if (t == Type::MEMORY) {
1720     st->print("  Memory:");
1721     MemNode::dump_adr_type(this, adr_type(), st);
1722   } else if (Verbose || WizardMode) {
1723     st->print("  Type:");
1724     if (t) {
1725       t->dump_on(st);
1726     } else {
1727       st->print("no type");
1728     }
1729   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
1730     // Dump MachSpillcopy vector type.
1731     t->dump_on(st);
1732   }
1733   if (is_new) {
1734     debug_only(dump_orig(debug_orig(), st));
1735     Node_Notes* nn = C->node_notes_at(_idx);
1736     if (nn != NULL && !nn->is_clear()) {
1737       if (nn->jvms() != NULL) {
1738         st->print(" !jvms:");
1739         nn->jvms()->dump_spec(st);
1740       }
1741     }
1742   }
1743   if (suffix) st->print("%s", suffix);
1744   C->_in_dump_cnt--;
1745 }
1746 
1747 //------------------------------dump_req--------------------------------------
1748 void Node::dump_req(outputStream *st) const {
1749   // Dump the required input edges
1750   for (uint i = 0; i < req(); i++) {    // For all required inputs
1751     Node* d = in(i);
1752     if (d == NULL) {
1753       st->print("_ ");
1754     } else if (NotANode(d)) {
1755       st->print("NotANode ");  // uninitialized, sentinel, garbage, etc.
1756     } else {
1757       st->print("%c%d ", Compile::current()->node_arena()->contains(d) ? ' ' : 'o', d->_idx);
1758     }
1759   }
1760 }
1761 
1762 
1763 //------------------------------dump_prec-------------------------------------
1764 void Node::dump_prec(outputStream *st) const {
1765   // Dump the precedence edges
1766   int any_prec = 0;
1767   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
1768     Node* p = in(i);
1769     if (p != NULL) {
1770       if (!any_prec++) st->print(" |");
1771       if (NotANode(p)) { st->print("NotANode "); continue; }
1772       st->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
1773     }
1774   }
1775 }
1776 
1777 //------------------------------dump_out--------------------------------------
1778 void Node::dump_out(outputStream *st) const {
1779   // Delimit the output edges
1780   st->print(" [[");
1781   // Dump the output edges
1782   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
1783     Node* u = _out[i];
1784     if (u == NULL) {
1785       st->print("_ ");
1786     } else if (NotANode(u)) {
1787       st->print("NotANode ");
1788     } else {
1789       st->print("%c%d ", Compile::current()->node_arena()->contains(u) ? ' ' : 'o', u->_idx);
1790     }
1791   }
1792   st->print("]] ");
1793 }
1794 
1795 //----------------------------collect_nodes_i----------------------------------
1796 // Collects nodes from an Ideal graph, starting from a given start node and
1797 // moving in a given direction until a certain depth (distance from the start
1798 // node) is reached. Duplicates are ignored.
1799 // Arguments:
1800 //   nstack:        the nodes are collected into this array.
1801 //   start:         the node at which to start collecting.
1802 //   direction:     if this is a positive number, collect input nodes; if it is
1803 //                  a negative number, collect output nodes.
1804 //   depth:         collect nodes up to this distance from the start node.
1805 //   include_start: whether to include the start node in the result collection.
1806 //   only_ctrl:     whether to regard control edges only during traversal.
1807 //   only_data:     whether to regard data edges only during traversal.
1808 static void collect_nodes_i(GrowableArray<Node*> *nstack, const Node* start, int direction, uint depth, bool include_start, bool only_ctrl, bool only_data) {
1809   Node* s = (Node*) start; // remove const
1810   nstack->append(s);
1811   int begin = 0;
1812   int end = 0;
1813   for(uint i = 0; i < depth; i++) {
1814     end = nstack->length();
1815     for(int j = begin; j < end; j++) {
1816       Node* tp  = nstack->at(j);
1817       uint limit = direction > 0 ? tp->len() : tp->outcnt();
1818       for(uint k = 0; k < limit; k++) {
1819         Node* n = direction > 0 ? tp->in(k) : tp->raw_out(k);
1820 
1821         if (NotANode(n))  continue;
1822         // do not recurse through top or the root (would reach unrelated stuff)
1823         if (n->is_Root() || n->is_top()) continue;
1824         if (only_ctrl && !n->is_CFG()) continue;
1825         if (only_data && n->is_CFG()) continue;
1826 
1827         bool on_stack = nstack->contains(n);
1828         if (!on_stack) {
1829           nstack->append(n);
1830         }
1831       }
1832     }
1833     begin = end;
1834   }
1835   if (!include_start) {
1836     nstack->remove(s);
1837   }
1838 }
1839 
1840 //------------------------------dump_nodes-------------------------------------
1841 static void dump_nodes(const Node* start, int d, bool only_ctrl) {
1842   if (NotANode(start)) return;
1843 
1844   GrowableArray <Node *> nstack(Compile::current()->live_nodes());
1845   collect_nodes_i(&nstack, start, d, (uint) ABS(d), true, only_ctrl, false);
1846 
1847   int end = nstack.length();
1848   if (d > 0) {
1849     for(int j = end-1; j >= 0; j--) {
1850       nstack.at(j)->dump();
1851     }
1852   } else {
1853     for(int j = 0; j < end; j++) {
1854       nstack.at(j)->dump();
1855     }
1856   }
1857 }
1858 
1859 //------------------------------dump-------------------------------------------
1860 void Node::dump(int d) const {
1861   dump_nodes(this, d, false);
1862 }
1863 
1864 //------------------------------dump_ctrl--------------------------------------
1865 // Dump a Node's control history to depth
1866 void Node::dump_ctrl(int d) const {
1867   dump_nodes(this, d, true);
1868 }
1869 
1870 //-----------------------------dump_compact------------------------------------
1871 void Node::dump_comp() const {
1872   this->dump_comp("\n");
1873 }
1874 
1875 //-----------------------------dump_compact------------------------------------
1876 // Dump a Node in compact representation, i.e., just print its name and index.
1877 // Nodes can specify additional specifics to print in compact representation by
1878 // implementing dump_compact_spec.
1879 void Node::dump_comp(const char* suffix, outputStream *st) const {
1880   Compile* C = Compile::current();
1881   C->_in_dump_cnt++;
1882   st->print("%s(%d)", Name(), _idx);
1883   this->dump_compact_spec(st);
1884   if (suffix) {
1885     st->print("%s", suffix);
1886   }
1887   C->_in_dump_cnt--;
1888 }
1889 
1890 //----------------------------dump_related-------------------------------------
1891 // Dump a Node's related nodes - the notion of "related" depends on the Node at
1892 // hand and is determined by the implementation of the virtual method rel.
1893 void Node::dump_related() const {
1894   Compile* C = Compile::current();
1895   GrowableArray <Node *> in_rel(C->unique());
1896   GrowableArray <Node *> out_rel(C->unique());
1897   this->related(&in_rel, &out_rel, false);
1898   for (int i = in_rel.length() - 1; i >= 0; i--) {
1899     in_rel.at(i)->dump();
1900   }
1901   this->dump("\n", true);
1902   for (int i = 0; i < out_rel.length(); i++) {
1903     out_rel.at(i)->dump();
1904   }
1905 }
1906 
1907 //----------------------------dump_related-------------------------------------
1908 // Dump a Node's related nodes up to a given depth (distance from the start
1909 // node).
1910 // Arguments:
1911 //   d_in:  depth for input nodes.
1912 //   d_out: depth for output nodes (note: this also is a positive number).
1913 void Node::dump_related(uint d_in, uint d_out) const {
1914   Compile* C = Compile::current();
1915   GrowableArray <Node *> in_rel(C->unique());
1916   GrowableArray <Node *> out_rel(C->unique());
1917 
1918   // call collect_nodes_i directly
1919   collect_nodes_i(&in_rel, this, 1, d_in, false, false, false);
1920   collect_nodes_i(&out_rel, this, -1, d_out, false, false, false);
1921 
1922   for (int i = in_rel.length() - 1; i >= 0; i--) {
1923     in_rel.at(i)->dump();
1924   }
1925   this->dump("\n", true);
1926   for (int i = 0; i < out_rel.length(); i++) {
1927     out_rel.at(i)->dump();
1928   }
1929 }
1930 
1931 //------------------------dump_related_compact---------------------------------
1932 // Dump a Node's related nodes in compact representation. The notion of
1933 // "related" depends on the Node at hand and is determined by the implementation
1934 // of the virtual method rel.
1935 void Node::dump_related_compact() const {
1936   Compile* C = Compile::current();
1937   GrowableArray <Node *> in_rel(C->unique());
1938   GrowableArray <Node *> out_rel(C->unique());
1939   this->related(&in_rel, &out_rel, true);
1940   int n_in = in_rel.length();
1941   int n_out = out_rel.length();
1942 
1943   this->dump_comp(n_in == 0 ? "\n" : "  ");
1944   for (int i = 0; i < n_in; i++) {
1945     in_rel.at(i)->dump_comp(i == n_in - 1 ? "\n" : "  ");
1946   }
1947   for (int i = 0; i < n_out; i++) {
1948     out_rel.at(i)->dump_comp(i == n_out - 1 ? "\n" : "  ");
1949   }
1950 }
1951 
1952 //------------------------------related----------------------------------------
1953 // Collect a Node's related nodes. The default behaviour just collects the
1954 // inputs and outputs at depth 1, including both control and data flow edges,
1955 // regardless of whether the presentation is compact or not. For data nodes,
1956 // the default is to collect all data inputs (till level 1 if compact), and
1957 // outputs till level 1.
1958 void Node::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
1959   if (this->is_CFG()) {
1960     collect_nodes_i(in_rel, this, 1, 1, false, false, false);
1961     collect_nodes_i(out_rel, this, -1, 1, false, false, false);
1962   } else {
1963     if (compact) {
1964       this->collect_nodes(in_rel, 1, false, true);
1965     } else {
1966       this->collect_nodes_in_all_data(in_rel, false);
1967     }
1968     this->collect_nodes(out_rel, -1, false, false);
1969   }
1970 }
1971 
1972 //---------------------------collect_nodes-------------------------------------
1973 // An entry point to the low-level node collection facility, to start from a
1974 // given node in the graph. The start node is by default not included in the
1975 // result.
1976 // Arguments:
1977 //   ns:   collect the nodes into this data structure.
1978 //   d:    the depth (distance from start node) to which nodes should be
1979 //         collected. A value >0 indicates input nodes, a value <0, output
1980 //         nodes.
1981 //   ctrl: include only control nodes.
1982 //   data: include only data nodes.
1983 void Node::collect_nodes(GrowableArray<Node*> *ns, int d, bool ctrl, bool data) const {
1984   if (ctrl && data) {
1985     // ignore nonsensical combination
1986     return;
1987   }
1988   collect_nodes_i(ns, this, d, (uint) ABS(d), false, ctrl, data);
1989 }
1990 
1991 //--------------------------collect_nodes_in-----------------------------------
1992 static void collect_nodes_in(Node* start, GrowableArray<Node*> *ns, bool primary_is_data, bool collect_secondary) {
1993   // The maximum depth is determined using a BFS that visits all primary (data
1994   // or control) inputs and increments the depth at each level.
1995   uint d_in = 0;
1996   GrowableArray<Node*> nodes(Compile::current()->unique());
1997   nodes.push(start);
1998   int nodes_at_current_level = 1;
1999   int n_idx = 0;
2000   while (nodes_at_current_level > 0) {
2001     // Add all primary inputs reachable from the current level to the list, and
2002     // increase the depth if there were any.
2003     int nodes_at_next_level = 0;
2004     bool nodes_added = false;
2005     while (nodes_at_current_level > 0) {
2006       nodes_at_current_level--;
2007       Node* current = nodes.at(n_idx++);
2008       for (uint i = 0; i < current->len(); i++) {
2009         Node* n = current->in(i);
2010         if (NotANode(n)) {
2011           continue;
2012         }
2013         if ((primary_is_data && n->is_CFG()) || (!primary_is_data && !n->is_CFG())) {
2014           continue;
2015         }
2016         if (!nodes.contains(n)) {
2017           nodes.push(n);
2018           nodes_added = true;
2019           nodes_at_next_level++;
2020         }
2021       }
2022     }
2023     if (nodes_added) {
2024       d_in++;
2025     }
2026     nodes_at_current_level = nodes_at_next_level;
2027   }
2028   start->collect_nodes(ns, d_in, !primary_is_data, primary_is_data);
2029   if (collect_secondary) {
2030     // Now, iterate over the secondary nodes in ns and add the respective
2031     // boundary reachable from them.
2032     GrowableArray<Node*> sns(Compile::current()->unique());
2033     for (GrowableArrayIterator<Node*> it = ns->begin(); it != ns->end(); ++it) {
2034       Node* n = *it;
2035       n->collect_nodes(&sns, 1, primary_is_data, !primary_is_data);
2036       for (GrowableArrayIterator<Node*> d = sns.begin(); d != sns.end(); ++d) {
2037         ns->append_if_missing(*d);
2038       }
2039       sns.clear();
2040     }
2041   }
2042 }
2043 
2044 //---------------------collect_nodes_in_all_data-------------------------------
2045 // Collect the entire data input graph. Include the control boundary if
2046 // requested.
2047 // Arguments:
2048 //   ns:   collect the nodes into this data structure.
2049 //   ctrl: if true, include the control boundary.
2050 void Node::collect_nodes_in_all_data(GrowableArray<Node*> *ns, bool ctrl) const {
2051   collect_nodes_in((Node*) this, ns, true, ctrl);
2052 }
2053 
2054 //--------------------------collect_nodes_in_all_ctrl--------------------------
2055 // Collect the entire control input graph. Include the data boundary if
2056 // requested.
2057 //   ns:   collect the nodes into this data structure.
2058 //   data: if true, include the control boundary.
2059 void Node::collect_nodes_in_all_ctrl(GrowableArray<Node*> *ns, bool data) const {
2060   collect_nodes_in((Node*) this, ns, false, data);
2061 }
2062 
2063 //------------------collect_nodes_out_all_ctrl_boundary------------------------
2064 // Collect the entire output graph until hitting control node boundaries, and
2065 // include those.
2066 void Node::collect_nodes_out_all_ctrl_boundary(GrowableArray<Node*> *ns) const {
2067   // Perform a BFS and stop at control nodes.
2068   GrowableArray<Node*> nodes(Compile::current()->unique());
2069   nodes.push((Node*) this);
2070   while (nodes.length() > 0) {
2071     Node* current = nodes.pop();
2072     if (NotANode(current)) {
2073       continue;
2074     }
2075     ns->append_if_missing(current);
2076     if (!current->is_CFG()) {
2077       for (DUIterator i = current->outs(); current->has_out(i); i++) {
2078         nodes.push(current->out(i));
2079       }
2080     }
2081   }
2082   ns->remove((Node*) this);
2083 }
2084 
2085 // VERIFICATION CODE
2086 // For each input edge to a node (ie - for each Use-Def edge), verify that
2087 // there is a corresponding Def-Use edge.
2088 //------------------------------verify_edges-----------------------------------
2089 void Node::verify_edges(Unique_Node_List &visited) {
2090   uint i, j, idx;
2091   int  cnt;
2092   Node *n;
2093 
2094   // Recursive termination test
2095   if (visited.member(this))  return;
2096   visited.push(this);
2097 
2098   // Walk over all input edges, checking for correspondence
2099   for( i = 0; i < len(); i++ ) {
2100     n = in(i);
2101     if (n != NULL && !n->is_top()) {
2102       // Count instances of (Node *)this
2103       cnt = 0;
2104       for (idx = 0; idx < n->_outcnt; idx++ ) {
2105         if (n->_out[idx] == (Node *)this)  cnt++;
2106       }
2107       assert( cnt > 0,"Failed to find Def-Use edge." );
2108       // Check for duplicate edges
2109       // walk the input array downcounting the input edges to n
2110       for( j = 0; j < len(); j++ ) {
2111         if( in(j) == n ) cnt--;
2112       }
2113       assert( cnt == 0,"Mismatched edge count.");
2114     } else if (n == NULL) {
2115       assert(i >= req() || i == 0 || is_Region() || is_Phi(), "only regions or phis have null data edges");
2116     } else {
2117       assert(n->is_top(), "sanity");
2118       // Nothing to check.
2119     }
2120   }
2121   // Recursive walk over all input edges
2122   for( i = 0; i < len(); i++ ) {
2123     n = in(i);
2124     if( n != NULL )
2125       in(i)->verify_edges(visited);
2126   }
2127 }
2128 
2129 //------------------------------verify_recur-----------------------------------
2130 static const Node *unique_top = NULL;
2131 
2132 void Node::verify_recur(const Node *n, int verify_depth,
2133                         VectorSet &old_space, VectorSet &new_space) {
2134   if ( verify_depth == 0 )  return;
2135   if (verify_depth > 0)  --verify_depth;
2136 
2137   Compile* C = Compile::current();
2138 
2139   // Contained in new_space or old_space?
2140   VectorSet *v = C->node_arena()->contains(n) ? &new_space : &old_space;
2141   // Check for visited in the proper space.  Numberings are not unique
2142   // across spaces so we need a separate VectorSet for each space.
2143   if( v->test_set(n->_idx) ) return;
2144 
2145   if (n->is_Con() && n->bottom_type() == Type::TOP) {
2146     if (C->cached_top_node() == NULL)
2147       C->set_cached_top_node((Node*)n);
2148     assert(C->cached_top_node() == n, "TOP node must be unique");
2149   }
2150 
2151   for( uint i = 0; i < n->len(); i++ ) {
2152     Node *x = n->in(i);
2153     if (!x || x->is_top()) continue;
2154 
2155     // Verify my input has a def-use edge to me
2156     if (true /*VerifyDefUse*/) {
2157       // Count use-def edges from n to x
2158       int cnt = 0;
2159       for( uint j = 0; j < n->len(); j++ )
2160         if( n->in(j) == x )
2161           cnt++;
2162       // Count def-use edges from x to n
2163       uint max = x->_outcnt;
2164       for( uint k = 0; k < max; k++ )
2165         if (x->_out[k] == n)
2166           cnt--;
2167       assert( cnt == 0, "mismatched def-use edge counts" );
2168     }
2169 
2170     verify_recur(x, verify_depth, old_space, new_space);
2171   }
2172 
2173 }
2174 
2175 //------------------------------verify-----------------------------------------
2176 // Check Def-Use info for my subgraph
2177 void Node::verify() const {
2178   Compile* C = Compile::current();
2179   Node* old_top = C->cached_top_node();
2180   ResourceMark rm;
2181   ResourceArea *area = Thread::current()->resource_area();
2182   VectorSet old_space(area), new_space(area);
2183   verify_recur(this, -1, old_space, new_space);
2184   C->set_cached_top_node(old_top);
2185 }
2186 #endif
2187 
2188 
2189 //------------------------------walk-------------------------------------------
2190 // Graph walk, with both pre-order and post-order functions
2191 void Node::walk(NFunc pre, NFunc post, void *env) {
2192   VectorSet visited(Thread::current()->resource_area()); // Setup for local walk
2193   walk_(pre, post, env, visited);
2194 }
2195 
2196 void Node::walk_(NFunc pre, NFunc post, void *env, VectorSet &visited) {
2197   if( visited.test_set(_idx) ) return;
2198   pre(*this,env);               // Call the pre-order walk function
2199   for( uint i=0; i<_max; i++ )
2200     if( in(i) )                 // Input exists and is not walked?
2201       in(i)->walk_(pre,post,env,visited); // Walk it with pre & post functions
2202   post(*this,env);              // Call the post-order walk function
2203 }
2204 
2205 void Node::nop(Node &, void*) {}
2206 
2207 //------------------------------Registers--------------------------------------
2208 // Do we Match on this edge index or not?  Generally false for Control
2209 // and true for everything else.  Weird for calls & returns.
2210 uint Node::match_edge(uint idx) const {
2211   return idx;                   // True for other than index 0 (control)
2212 }
2213 
2214 static RegMask _not_used_at_all;
2215 // Register classes are defined for specific machines
2216 const RegMask &Node::out_RegMask() const {
2217   ShouldNotCallThis();
2218   return _not_used_at_all;
2219 }
2220 
2221 const RegMask &Node::in_RegMask(uint) const {
2222   ShouldNotCallThis();
2223   return _not_used_at_all;
2224 }
2225 
2226 //=============================================================================
2227 //-----------------------------------------------------------------------------
2228 void Node_Array::reset( Arena *new_arena ) {
2229   _a->Afree(_nodes,_max*sizeof(Node*));
2230   _max   = 0;
2231   _nodes = NULL;
2232   _a     = new_arena;
2233 }
2234 
2235 //------------------------------clear------------------------------------------
2236 // Clear all entries in _nodes to NULL but keep storage
2237 void Node_Array::clear() {
2238   Copy::zero_to_bytes( _nodes, _max*sizeof(Node*) );
2239 }
2240 
2241 //-----------------------------------------------------------------------------
2242 void Node_Array::grow( uint i ) {
2243   if( !_max ) {
2244     _max = 1;
2245     _nodes = (Node**)_a->Amalloc( _max * sizeof(Node*) );
2246     _nodes[0] = NULL;
2247   }
2248   uint old = _max;
2249   while( i >= _max ) _max <<= 1;        // Double to fit
2250   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2251   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2252 }
2253 
2254 //-----------------------------------------------------------------------------
2255 void Node_Array::insert( uint i, Node *n ) {
2256   if( _nodes[_max-1] ) grow(_max);      // Get more space if full
2257   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i+1], ((_max-i-1)*sizeof(Node*)));
2258   _nodes[i] = n;
2259 }
2260 
2261 //-----------------------------------------------------------------------------
2262 void Node_Array::remove( uint i ) {
2263   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i+1], (HeapWord*)&_nodes[i], ((_max-i-1)*sizeof(Node*)));
2264   _nodes[_max-1] = NULL;
2265 }
2266 
2267 //-----------------------------------------------------------------------------
2268 void Node_Array::sort( C_sort_func_t func) {
2269   qsort( _nodes, _max, sizeof( Node* ), func );
2270 }
2271 
2272 //-----------------------------------------------------------------------------
2273 void Node_Array::dump() const {
2274 #ifndef PRODUCT
2275   for( uint i = 0; i < _max; i++ ) {
2276     Node *nn = _nodes[i];
2277     if( nn != NULL ) {
2278       tty->print("%5d--> ",i); nn->dump();
2279     }
2280   }
2281 #endif
2282 }
2283 
2284 //--------------------------is_iteratively_computed------------------------------
2285 // Operation appears to be iteratively computed (such as an induction variable)
2286 // It is possible for this operation to return false for a loop-varying
2287 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2288 bool Node::is_iteratively_computed() {
2289   if (ideal_reg()) { // does operation have a result register?
2290     for (uint i = 1; i < req(); i++) {
2291       Node* n = in(i);
2292       if (n != NULL && n->is_Phi()) {
2293         for (uint j = 1; j < n->req(); j++) {
2294           if (n->in(j) == this) {
2295             return true;
2296           }
2297         }
2298       }
2299     }
2300   }
2301   return false;
2302 }
2303 
2304 //--------------------------find_similar------------------------------
2305 // Return a node with opcode "opc" and same inputs as "this" if one can
2306 // be found; Otherwise return NULL;
2307 Node* Node::find_similar(int opc) {
2308   if (req() >= 2) {
2309     Node* def = in(1);
2310     if (def && def->outcnt() >= 2) {
2311       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2312         Node* use = def->fast_out(i);
2313         if (use != this &&
2314             use->Opcode() == opc &&
2315             use->req() == req()) {
2316           uint j;
2317           for (j = 0; j < use->req(); j++) {
2318             if (use->in(j) != in(j)) {
2319               break;
2320             }
2321           }
2322           if (j == use->req()) {
2323             return use;
2324           }
2325         }
2326       }
2327     }
2328   }
2329   return NULL;
2330 }
2331 
2332 
2333 //--------------------------unique_ctrl_out------------------------------
2334 // Return the unique control out if only one. Null if none or more than one.
2335 Node* Node::unique_ctrl_out() const {
2336   Node* found = NULL;
2337   for (uint i = 0; i < outcnt(); i++) {
2338     Node* use = raw_out(i);
2339     if (use->is_CFG() && use != this) {
2340       if (found != NULL) return NULL;
2341       found = use;
2342     }
2343   }
2344   return found;
2345 }
2346 
2347 void Node::ensure_control_or_add_prec(Node* c) {
2348   if (in(0) == NULL) {
2349     set_req(0, c);
2350   } else if (in(0) != c) {
2351     add_prec(c);
2352   }
2353 }
2354 
2355 //=============================================================================
2356 //------------------------------yank-------------------------------------------
2357 // Find and remove
2358 void Node_List::yank( Node *n ) {
2359   uint i;
2360   for( i = 0; i < _cnt; i++ )
2361     if( _nodes[i] == n )
2362       break;
2363 
2364   if( i < _cnt )
2365     _nodes[i] = _nodes[--_cnt];
2366 }
2367 
2368 //------------------------------dump-------------------------------------------
2369 void Node_List::dump() const {
2370 #ifndef PRODUCT
2371   for( uint i = 0; i < _cnt; i++ )
2372     if( _nodes[i] ) {
2373       tty->print("%5d--> ",i);
2374       _nodes[i]->dump();
2375     }
2376 #endif
2377 }
2378 
2379 void Node_List::dump_simple() const {
2380 #ifndef PRODUCT
2381   for( uint i = 0; i < _cnt; i++ )
2382     if( _nodes[i] ) {
2383       tty->print(" %d", _nodes[i]->_idx);
2384     } else {
2385       tty->print(" NULL");
2386     }
2387 #endif
2388 }
2389 
2390 //=============================================================================
2391 //------------------------------remove-----------------------------------------
2392 void Unique_Node_List::remove( Node *n ) {
2393   if( _in_worklist[n->_idx] ) {
2394     for( uint i = 0; i < size(); i++ )
2395       if( _nodes[i] == n ) {
2396         map(i,Node_List::pop());
2397         _in_worklist >>= n->_idx;
2398         return;
2399       }
2400     ShouldNotReachHere();
2401   }
2402 }
2403 
2404 //-----------------------remove_useless_nodes----------------------------------
2405 // Remove useless nodes from worklist
2406 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2407 
2408   for( uint i = 0; i < size(); ++i ) {
2409     Node *n = at(i);
2410     assert( n != NULL, "Did not expect null entries in worklist");
2411     if( ! useful.test(n->_idx) ) {
2412       _in_worklist >>= n->_idx;
2413       map(i,Node_List::pop());
2414       // Node *replacement = Node_List::pop();
2415       // if( i != size() ) { // Check if removing last entry
2416       //   _nodes[i] = replacement;
2417       // }
2418       --i;  // Visit popped node
2419       // If it was last entry, loop terminates since size() was also reduced
2420     }
2421   }
2422 }
2423 
2424 //=============================================================================
2425 void Node_Stack::grow() {
2426   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2427   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2428   size_t max = old_max << 1;             // max * 2
2429   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2430   _inode_max = _inodes + max;
2431   _inode_top = _inodes + old_top;        // restore _top
2432 }
2433 
2434 // Node_Stack is used to map nodes.
2435 Node* Node_Stack::find(uint idx) const {
2436   uint sz = size();
2437   for (uint i=0; i < sz; i++) {
2438     if (idx == index_at(i) )
2439       return node_at(i);
2440   }
2441   return NULL;
2442 }
2443 
2444 //=============================================================================
2445 uint TypeNode::size_of() const { return sizeof(*this); }
2446 #ifndef PRODUCT
2447 void TypeNode::dump_spec(outputStream *st) const {
2448   if( !Verbose && !WizardMode ) {
2449     // standard dump does this in Verbose and WizardMode
2450     st->print(" #"); _type->dump_on(st);
2451   }
2452 }
2453 
2454 void TypeNode::dump_compact_spec(outputStream *st) const {
2455   st->print("#");
2456   _type->dump_on(st);
2457 }
2458 #endif
2459 uint TypeNode::hash() const {
2460   return Node::hash() + _type->hash();
2461 }
2462 uint TypeNode::cmp( const Node &n ) const
2463 { return !Type::cmp( _type, ((TypeNode&)n)._type ); }
2464 const Type *TypeNode::bottom_type() const { return _type; }
2465 const Type* TypeNode::Value(PhaseGVN* phase) const { return _type; }
2466 
2467 //------------------------------ideal_reg--------------------------------------
2468 uint TypeNode::ideal_reg() const {
2469   return _type->ideal_reg();
2470 }