1 /*
   2  * Copyright (c) 1997, 2016, 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/rootnode.hpp"
  41 #include "opto/type.hpp"
  42 #include "utilities/copy.hpp"
  43 #include "utilities/macros.hpp"
  44 
  45 class RegMask;
  46 // #include "phase.hpp"
  47 class PhaseTransform;
  48 class PhaseGVN;
  49 
  50 // Arena we are currently building Nodes in
  51 const uint Node::NotAMachineReg = 0xffff0000;
  52 
  53 #ifndef PRODUCT
  54 extern int nodes_created;
  55 #endif
  56 #ifdef __clang__
  57 #pragma clang diagnostic push
  58 #pragma GCC diagnostic ignored "-Wuninitialized"
  59 #endif
  60 
  61 #ifdef ASSERT
  62 
  63 //-------------------------- construct_node------------------------------------
  64 // Set a breakpoint here to identify where a particular node index is built.
  65 void Node::verify_construction() {
  66   _debug_orig = NULL;
  67   int old_debug_idx = Compile::debug_idx();
  68   int new_debug_idx = old_debug_idx+1;
  69   if (new_debug_idx > 0) {
  70     // Arrange that the lowest five decimal digits of _debug_idx
  71     // will repeat those of _idx. In case this is somehow pathological,
  72     // we continue to assign negative numbers (!) consecutively.
  73     const int mod = 100000;
  74     int bump = (int)(_idx - new_debug_idx) % mod;
  75     if (bump < 0)  bump += mod;
  76     assert(bump >= 0 && bump < mod, "");
  77     new_debug_idx += bump;
  78   }
  79   Compile::set_debug_idx(new_debug_idx);
  80   set_debug_idx( new_debug_idx );
  81   assert(Compile::current()->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  82   assert(Compile::current()->live_nodes() < Compile::current()->max_node_limit(), "Live Node limit exceeded limit");
  83   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (int)_idx == BreakAtNode)) {
  84     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d", _idx, _debug_idx);
  85     BREAKPOINT;
  86   }
  87 #if OPTO_DU_ITERATOR_ASSERT
  88   _last_del = NULL;
  89   _del_tick = 0;
  90 #endif
  91   _hash_lock = 0;
  92 }
  93 
  94 
  95 // #ifdef ASSERT ...
  96 
  97 #if OPTO_DU_ITERATOR_ASSERT
  98 void DUIterator_Common::sample(const Node* node) {
  99   _vdui     = VerifyDUIterators;
 100   _node     = node;
 101   _outcnt   = node->_outcnt;
 102   _del_tick = node->_del_tick;
 103   _last     = NULL;
 104 }
 105 
 106 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
 107   assert(_node     == node, "consistent iterator source");
 108   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
 109 }
 110 
 111 void DUIterator_Common::verify_resync() {
 112   // Ensure that the loop body has just deleted the last guy produced.
 113   const Node* node = _node;
 114   // Ensure that at least one copy of the last-seen edge was deleted.
 115   // Note:  It is OK to delete multiple copies of the last-seen edge.
 116   // Unfortunately, we have no way to verify that all the deletions delete
 117   // that same edge.  On this point we must use the Honor System.
 118   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 119   assert(node->_last_del == _last, "must have deleted the edge just produced");
 120   // We liked this deletion, so accept the resulting outcnt and tick.
 121   _outcnt   = node->_outcnt;
 122   _del_tick = node->_del_tick;
 123 }
 124 
 125 void DUIterator_Common::reset(const DUIterator_Common& that) {
 126   if (this == &that)  return;  // ignore assignment to self
 127   if (!_vdui) {
 128     // We need to initialize everything, overwriting garbage values.
 129     _last = that._last;
 130     _vdui = that._vdui;
 131   }
 132   // Note:  It is legal (though odd) for an iterator over some node x
 133   // to be reassigned to iterate over another node y.  Some doubly-nested
 134   // progress loops depend on being able to do this.
 135   const Node* node = that._node;
 136   // Re-initialize everything, except _last.
 137   _node     = node;
 138   _outcnt   = node->_outcnt;
 139   _del_tick = node->_del_tick;
 140 }
 141 
 142 void DUIterator::sample(const Node* node) {
 143   DUIterator_Common::sample(node);      // Initialize the assertion data.
 144   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 145 }
 146 
 147 void DUIterator::verify(const Node* node, bool at_end_ok) {
 148   DUIterator_Common::verify(node, at_end_ok);
 149   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 150 }
 151 
 152 void DUIterator::verify_increment() {
 153   if (_refresh_tick & 1) {
 154     // We have refreshed the index during this loop.
 155     // Fix up _idx to meet asserts.
 156     if (_idx > _outcnt)  _idx = _outcnt;
 157   }
 158   verify(_node, true);
 159 }
 160 
 161 void DUIterator::verify_resync() {
 162   // Note:  We do not assert on _outcnt, because insertions are OK here.
 163   DUIterator_Common::verify_resync();
 164   // Make sure we are still in sync, possibly with no more out-edges:
 165   verify(_node, true);
 166 }
 167 
 168 void DUIterator::reset(const DUIterator& that) {
 169   if (this == &that)  return;  // self assignment is always a no-op
 170   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 171   assert(that._idx          == 0, "assign only the result of Node::outs()");
 172   assert(_idx               == that._idx, "already assigned _idx");
 173   if (!_vdui) {
 174     // We need to initialize everything, overwriting garbage values.
 175     sample(that._node);
 176   } else {
 177     DUIterator_Common::reset(that);
 178     if (_refresh_tick & 1) {
 179       _refresh_tick++;                  // Clear the "was refreshed" flag.
 180     }
 181     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 182   }
 183 }
 184 
 185 void DUIterator::refresh() {
 186   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 187   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 188 }
 189 
 190 void DUIterator::verify_finish() {
 191   // If the loop has killed the node, do not require it to re-run.
 192   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 193   // If this assert triggers, it means that a loop used refresh_out_pos
 194   // to re-synch an iteration index, but the loop did not correctly
 195   // re-run itself, using a "while (progress)" construct.
 196   // This iterator enforces the rule that you must keep trying the loop
 197   // until it "runs clean" without any need for refreshing.
 198   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 199 }
 200 
 201 
 202 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 203   DUIterator_Common::verify(node, at_end_ok);
 204   Node** out    = node->_out;
 205   uint   cnt    = node->_outcnt;
 206   assert(cnt == _outcnt, "no insertions allowed");
 207   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 208   // This last check is carefully designed to work for NO_OUT_ARRAY.
 209 }
 210 
 211 void DUIterator_Fast::verify_limit() {
 212   const Node* node = _node;
 213   verify(node, true);
 214   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 215 }
 216 
 217 void DUIterator_Fast::verify_resync() {
 218   const Node* node = _node;
 219   if (_outp == node->_out + _outcnt) {
 220     // Note that the limit imax, not the pointer i, gets updated with the
 221     // exact count of deletions.  (For the pointer it's always "--i".)
 222     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 223     // This is a limit pointer, with a name like "imax".
 224     // Fudge the _last field so that the common assert will be happy.
 225     _last = (Node*) node->_last_del;
 226     DUIterator_Common::verify_resync();
 227   } else {
 228     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 229     // A normal internal pointer.
 230     DUIterator_Common::verify_resync();
 231     // Make sure we are still in sync, possibly with no more out-edges:
 232     verify(node, true);
 233   }
 234 }
 235 
 236 void DUIterator_Fast::verify_relimit(uint n) {
 237   const Node* node = _node;
 238   assert((int)n > 0, "use imax -= n only with a positive count");
 239   // This must be a limit pointer, with a name like "imax".
 240   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 241   // The reported number of deletions must match what the node saw.
 242   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 243   // Fudge the _last field so that the common assert will be happy.
 244   _last = (Node*) node->_last_del;
 245   DUIterator_Common::verify_resync();
 246 }
 247 
 248 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 249   assert(_outp              == that._outp, "already assigned _outp");
 250   DUIterator_Common::reset(that);
 251 }
 252 
 253 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 254   // at_end_ok means the _outp is allowed to underflow by 1
 255   _outp += at_end_ok;
 256   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 257   _outp -= at_end_ok;
 258   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 259 }
 260 
 261 void DUIterator_Last::verify_limit() {
 262   // Do not require the limit address to be resynched.
 263   //verify(node, true);
 264   assert(_outp == _node->_out, "limit still correct");
 265 }
 266 
 267 void DUIterator_Last::verify_step(uint num_edges) {
 268   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 269   _outcnt   -= num_edges;
 270   _del_tick += num_edges;
 271   // Make sure we are still in sync, possibly with no more out-edges:
 272   const Node* node = _node;
 273   verify(node, true);
 274   assert(node->_last_del == _last, "must have deleted the edge just produced");
 275 }
 276 
 277 #endif //OPTO_DU_ITERATOR_ASSERT
 278 
 279 
 280 #endif //ASSERT
 281 
 282 
 283 // This constant used to initialize _out may be any non-null value.
 284 // The value NULL is reserved for the top node only.
 285 #define NO_OUT_ARRAY ((Node**)-1)
 286 
 287 // Out-of-line code from node constructors.
 288 // Executed only when extra debug info. is being passed around.
 289 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 290   C->set_node_notes_at(idx, nn);
 291 }
 292 
 293 // Shared initialization code.
 294 inline int Node::Init(int req) {
 295   Compile* C = Compile::current();
 296   int idx = C->next_unique();
 297 
 298   // Allocate memory for the necessary number of edges.
 299   if (req > 0) {
 300     // Allocate space for _in array to have double alignment.
 301     _in = (Node **) ((char *) (C->node_arena()->Amalloc_D(req * sizeof(void*))));
 302   }
 303   // If there are default notes floating around, capture them:
 304   Node_Notes* nn = C->default_node_notes();
 305   if (nn != NULL)  init_node_notes(C, idx, nn);
 306 
 307   // Note:  At this point, C is dead,
 308   // and we begin to initialize the new Node.
 309 
 310   _cnt = _max = req;
 311   _outcnt = _outmax = 0;
 312   _class_id = Class_Node;
 313   _flags = 0;
 314   _out = NO_OUT_ARRAY;
 315   return idx;
 316 }
 317 
 318 //------------------------------Node-------------------------------------------
 319 // Create a Node, with a given number of required edges.
 320 Node::Node(uint req)
 321   : _idx(Init(req))
 322 #ifdef ASSERT
 323   , _parse_idx(_idx)
 324 #endif
 325 {
 326   assert( req < Compile::current()->max_node_limit() - NodeLimitFudgeFactor, "Input limit exceeded" );
 327   debug_only( verify_construction() );
 328   NOT_PRODUCT(nodes_created++);
 329   if (req == 0) {
 330     _in = NULL;
 331   } else {
 332     Node** to = _in;
 333     for(uint i = 0; i < req; i++) {
 334       to[i] = NULL;
 335     }
 336   }
 337 }
 338 
 339 //------------------------------Node-------------------------------------------
 340 Node::Node(Node *n0)
 341   : _idx(Init(1))
 342 #ifdef ASSERT
 343   , _parse_idx(_idx)
 344 #endif
 345 {
 346   debug_only( verify_construction() );
 347   NOT_PRODUCT(nodes_created++);
 348   assert( is_not_dead(n0), "can not use dead node");
 349   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 350 }
 351 
 352 //------------------------------Node-------------------------------------------
 353 Node::Node(Node *n0, Node *n1)
 354   : _idx(Init(2))
 355 #ifdef ASSERT
 356   , _parse_idx(_idx)
 357 #endif
 358 {
 359   debug_only( verify_construction() );
 360   NOT_PRODUCT(nodes_created++);
 361   assert( is_not_dead(n0), "can not use dead node");
 362   assert( is_not_dead(n1), "can not use dead node");
 363   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 364   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 365 }
 366 
 367 //------------------------------Node-------------------------------------------
 368 Node::Node(Node *n0, Node *n1, Node *n2)
 369   : _idx(Init(3))
 370 #ifdef ASSERT
 371   , _parse_idx(_idx)
 372 #endif
 373 {
 374   debug_only( verify_construction() );
 375   NOT_PRODUCT(nodes_created++);
 376   assert( is_not_dead(n0), "can not use dead node");
 377   assert( is_not_dead(n1), "can not use dead node");
 378   assert( is_not_dead(n2), "can not use dead node");
 379   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 380   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 381   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 382 }
 383 
 384 //------------------------------Node-------------------------------------------
 385 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 386   : _idx(Init(4))
 387 #ifdef ASSERT
 388   , _parse_idx(_idx)
 389 #endif
 390 {
 391   debug_only( verify_construction() );
 392   NOT_PRODUCT(nodes_created++);
 393   assert( is_not_dead(n0), "can not use dead node");
 394   assert( is_not_dead(n1), "can not use dead node");
 395   assert( is_not_dead(n2), "can not use dead node");
 396   assert( is_not_dead(n3), "can not use dead node");
 397   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 398   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 399   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 400   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 401 }
 402 
 403 //------------------------------Node-------------------------------------------
 404 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 405   : _idx(Init(5))
 406 #ifdef ASSERT
 407   , _parse_idx(_idx)
 408 #endif
 409 {
 410   debug_only( verify_construction() );
 411   NOT_PRODUCT(nodes_created++);
 412   assert( is_not_dead(n0), "can not use dead node");
 413   assert( is_not_dead(n1), "can not use dead node");
 414   assert( is_not_dead(n2), "can not use dead node");
 415   assert( is_not_dead(n3), "can not use dead node");
 416   assert( is_not_dead(n4), "can not use dead node");
 417   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 418   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 419   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 420   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 421   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 422 }
 423 
 424 //------------------------------Node-------------------------------------------
 425 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 426                      Node *n4, Node *n5)
 427   : _idx(Init(6))
 428 #ifdef ASSERT
 429   , _parse_idx(_idx)
 430 #endif
 431 {
 432   debug_only( verify_construction() );
 433   NOT_PRODUCT(nodes_created++);
 434   assert( is_not_dead(n0), "can not use dead node");
 435   assert( is_not_dead(n1), "can not use dead node");
 436   assert( is_not_dead(n2), "can not use dead node");
 437   assert( is_not_dead(n3), "can not use dead node");
 438   assert( is_not_dead(n4), "can not use dead node");
 439   assert( is_not_dead(n5), "can not use dead node");
 440   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 441   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 442   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 443   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 444   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 445   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 446 }
 447 
 448 //------------------------------Node-------------------------------------------
 449 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 450                      Node *n4, Node *n5, Node *n6)
 451   : _idx(Init(7))
 452 #ifdef ASSERT
 453   , _parse_idx(_idx)
 454 #endif
 455 {
 456   debug_only( verify_construction() );
 457   NOT_PRODUCT(nodes_created++);
 458   assert( is_not_dead(n0), "can not use dead node");
 459   assert( is_not_dead(n1), "can not use dead node");
 460   assert( is_not_dead(n2), "can not use dead node");
 461   assert( is_not_dead(n3), "can not use dead node");
 462   assert( is_not_dead(n4), "can not use dead node");
 463   assert( is_not_dead(n5), "can not use dead node");
 464   assert( is_not_dead(n6), "can not use dead node");
 465   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 466   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 467   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 468   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 469   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 470   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 471   _in[6] = n6; if (n6 != NULL) n6->add_out((Node *)this);
 472 }
 473 
 474 #ifdef __clang__
 475 #pragma clang diagnostic pop
 476 #endif
 477 
 478 
 479 //------------------------------clone------------------------------------------
 480 // Clone a Node.
 481 Node *Node::clone() const {
 482   Compile* C = Compile::current();
 483   uint s = size_of();           // Size of inherited Node
 484   Node *n = (Node*)C->node_arena()->Amalloc_D(size_of() + _max*sizeof(Node*));
 485   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 486   // Set the new input pointer array
 487   n->_in = (Node**)(((char*)n)+s);
 488   // Cannot share the old output pointer array, so kill it
 489   n->_out = NO_OUT_ARRAY;
 490   // And reset the counters to 0
 491   n->_outcnt = 0;
 492   n->_outmax = 0;
 493   // Unlock this guy, since he is not in any hash table.
 494   debug_only(n->_hash_lock = 0);
 495   // Walk the old node's input list to duplicate its edges
 496   uint i;
 497   for( i = 0; i < len(); i++ ) {
 498     Node *x = in(i);
 499     n->_in[i] = x;
 500     if (x != NULL) x->add_out(n);
 501   }
 502   if (is_macro())
 503     C->add_macro_node(n);
 504   if (is_expensive())
 505     C->add_expensive_node(n);
 506   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 507   bs->register_potential_barrier_node(n);
 508   // If the cloned node is a range check dependent CastII, add it to the list.
 509   CastIINode* cast = n->isa_CastII();
 510   if (cast != NULL && cast->has_range_check()) {
 511     C->add_range_check_cast(cast);
 512   }
 513   if (n->Opcode() == Op_Opaque4) {
 514     C->add_opaque4_node(n);
 515   }
 516 
 517   n->set_idx(C->next_unique()); // Get new unique index as well
 518   debug_only( n->verify_construction() );
 519   NOT_PRODUCT(nodes_created++);
 520   // Do not patch over the debug_idx of a clone, because it makes it
 521   // impossible to break on the clone's moment of creation.
 522   //debug_only( n->set_debug_idx( debug_idx() ) );
 523 
 524   C->copy_node_notes_to(n, (Node*) this);
 525 
 526   // MachNode clone
 527   uint nopnds;
 528   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 529     MachNode *mach  = n->as_Mach();
 530     MachNode *mthis = this->as_Mach();
 531     // Get address of _opnd_array.
 532     // It should be the same offset since it is the clone of this node.
 533     MachOper **from = mthis->_opnds;
 534     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 535                     pointer_delta((const void*)from,
 536                                   (const void*)(&mthis->_opnds), 1));
 537     mach->_opnds = to;
 538     for ( uint i = 0; i < nopnds; ++i ) {
 539       to[i] = from[i]->clone();
 540     }
 541   }
 542   // cloning CallNode may need to clone JVMState
 543   if (n->is_Call()) {
 544     n->as_Call()->clone_jvms(C);
 545   }
 546   if (n->is_SafePoint()) {
 547     n->as_SafePoint()->clone_replaced_nodes();
 548   }
 549   if (n->is_Load()) {
 550     n->as_Load()->copy_barrier_info(this);
 551   }
 552   return n;                     // Return the clone
 553 }
 554 
 555 //---------------------------setup_is_top--------------------------------------
 556 // Call this when changing the top node, to reassert the invariants
 557 // required by Node::is_top.  See Compile::set_cached_top_node.
 558 void Node::setup_is_top() {
 559   if (this == (Node*)Compile::current()->top()) {
 560     // This node has just become top.  Kill its out array.
 561     _outcnt = _outmax = 0;
 562     _out = NULL;                           // marker value for top
 563     assert(is_top(), "must be top");
 564   } else {
 565     if (_out == NULL)  _out = NO_OUT_ARRAY;
 566     assert(!is_top(), "must not be top");
 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 // Optionally, keep casts with dependencies.
 897 Node* Node::uncast(bool keep_deps) const {
 898   // Should be inline:
 899   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 900   if (is_ConstraintCast()) {
 901     return uncast_helper(this, keep_deps);
 902   } else {
 903     return (Node*) this;
 904   }
 905 }
 906 
 907 // Find out of current node that matches opcode.
 908 Node* Node::find_out_with(int opcode) {
 909   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 910     Node* use = fast_out(i);
 911     if (use->Opcode() == opcode) {
 912       return use;
 913     }
 914   }
 915   return NULL;
 916 }
 917 
 918 // Return true if the current node has an out that matches opcode.
 919 bool Node::has_out_with(int opcode) {
 920   return (find_out_with(opcode) != NULL);
 921 }
 922 
 923 // Return true if the current node has an out that matches any of the opcodes.
 924 bool Node::has_out_with(int opcode1, int opcode2, int opcode3, int opcode4) {
 925   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 926       int opcode = fast_out(i)->Opcode();
 927       if (opcode == opcode1 || opcode == opcode2 || opcode == opcode3 || opcode == opcode4) {
 928         return true;
 929       }
 930   }
 931   return false;
 932 }
 933 
 934 
 935 //---------------------------uncast_helper-------------------------------------
 936 Node* Node::uncast_helper(const Node* p, bool keep_deps) {
 937 #ifdef ASSERT
 938   uint depth_count = 0;
 939   const Node* orig_p = p;
 940 #endif
 941 
 942   while (true) {
 943 #ifdef ASSERT
 944     if (depth_count >= K) {
 945       orig_p->dump(4);
 946       if (p != orig_p)
 947         p->dump(1);
 948     }
 949     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
 950 #endif
 951     if (p == NULL || p->req() != 2) {
 952       break;
 953     } else if (p->is_ConstraintCast()) {
 954       if (keep_deps && p->as_ConstraintCast()->carry_dependency()) {
 955         break; // stop at casts with dependencies
 956       }
 957       p = p->in(1);
 958     } else {
 959       break;
 960     }
 961   }
 962   return (Node*) p;
 963 }
 964 
 965 //------------------------------add_prec---------------------------------------
 966 // Add a new precedence input.  Precedence inputs are unordered, with
 967 // duplicates removed and NULLs packed down at the end.
 968 void Node::add_prec( Node *n ) {
 969   assert( is_not_dead(n), "can not use dead node");
 970 
 971   // Check for NULL at end
 972   if( _cnt >= _max || in(_max-1) )
 973     grow( _max+1 );
 974 
 975   // Find a precedence edge to move
 976   uint i = _cnt;
 977   while( in(i) != NULL ) {
 978     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
 979     i++;
 980   }
 981   _in[i] = n;                                // Stuff prec edge over NULL
 982   if ( n != NULL) n->add_out((Node *)this);  // Add mirror edge
 983 
 984 #ifdef ASSERT
 985   while ((++i)<_max) { assert(_in[i] == NULL, "spec violation: Gap in prec edges (node %d)", _idx); }
 986 #endif
 987 }
 988 
 989 //------------------------------rm_prec----------------------------------------
 990 // Remove a precedence input.  Precedence inputs are unordered, with
 991 // duplicates removed and NULLs packed down at the end.
 992 void Node::rm_prec( uint j ) {
 993   assert(j < _max, "oob: i=%d, _max=%d", j, _max);
 994   assert(j >= _cnt, "not a precedence edge");
 995   if (_in[j] == NULL) return;   // Avoid spec violation: Gap in prec edges.
 996   _in[j]->del_out((Node *)this);
 997   close_prec_gap_at(j);
 998 }
 999 
1000 //------------------------------size_of----------------------------------------
1001 uint Node::size_of() const { return sizeof(*this); }
1002 
1003 //------------------------------ideal_reg--------------------------------------
1004 uint Node::ideal_reg() const { return 0; }
1005 
1006 //------------------------------jvms-------------------------------------------
1007 JVMState* Node::jvms() const { return NULL; }
1008 
1009 #ifdef ASSERT
1010 //------------------------------jvms-------------------------------------------
1011 bool Node::verify_jvms(const JVMState* using_jvms) const {
1012   for (JVMState* jvms = this->jvms(); jvms != NULL; jvms = jvms->caller()) {
1013     if (jvms == using_jvms)  return true;
1014   }
1015   return false;
1016 }
1017 
1018 //------------------------------init_NodeProperty------------------------------
1019 void Node::init_NodeProperty() {
1020   assert(_max_classes <= max_jushort, "too many NodeProperty classes");
1021   assert(_max_flags <= max_jushort, "too many NodeProperty flags");
1022 }
1023 #endif
1024 
1025 //------------------------------format-----------------------------------------
1026 // Print as assembly
1027 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1028 //------------------------------emit-------------------------------------------
1029 // Emit bytes starting at parameter 'ptr'.
1030 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
1031 //------------------------------size-------------------------------------------
1032 // Size of instruction in bytes
1033 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1034 
1035 //------------------------------CFG Construction-------------------------------
1036 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1037 // Goto and Return.
1038 const Node *Node::is_block_proj() const { return 0; }
1039 
1040 // Minimum guaranteed type
1041 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1042 
1043 
1044 //------------------------------raise_bottom_type------------------------------
1045 // Get the worst-case Type output for this Node.
1046 void Node::raise_bottom_type(const Type* new_type) {
1047   if (is_Type()) {
1048     TypeNode *n = this->as_Type();
1049     if (VerifyAliases) {
1050       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1051     }
1052     n->set_type(new_type);
1053   } else if (is_Load()) {
1054     LoadNode *n = this->as_Load();
1055     if (VerifyAliases) {
1056       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1057     }
1058     n->set_type(new_type);
1059   }
1060 }
1061 
1062 //------------------------------Identity---------------------------------------
1063 // Return a node that the given node is equivalent to.
1064 Node* Node::Identity(PhaseGVN* phase) {
1065   return this;                  // Default to no identities
1066 }
1067 
1068 //------------------------------Value------------------------------------------
1069 // Compute a new Type for a node using the Type of the inputs.
1070 const Type* Node::Value(PhaseGVN* phase) const {
1071   return bottom_type();         // Default to worst-case Type
1072 }
1073 
1074 //------------------------------Ideal------------------------------------------
1075 //
1076 // 'Idealize' the graph rooted at this Node.
1077 //
1078 // In order to be efficient and flexible there are some subtle invariants
1079 // these Ideal calls need to hold.  Running with '+VerifyIterativeGVN' checks
1080 // these invariants, although its too slow to have on by default.  If you are
1081 // hacking an Ideal call, be sure to test with +VerifyIterativeGVN!
1082 //
1083 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1084 // pointer.  If ANY change is made, it must return the root of the reshaped
1085 // graph - even if the root is the same Node.  Example: swapping the inputs
1086 // to an AddINode gives the same answer and same root, but you still have to
1087 // return the 'this' pointer instead of NULL.
1088 //
1089 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1090 // Identity call to return an old Node; basically if Identity can find
1091 // another Node have the Ideal call make no change and return NULL.
1092 // Example: AddINode::Ideal must check for add of zero; in this case it
1093 // returns NULL instead of doing any graph reshaping.
1094 //
1095 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1096 // sharing there may be other users of the old Nodes relying on their current
1097 // semantics.  Modifying them will break the other users.
1098 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1099 // "X+3" unchanged in case it is shared.
1100 //
1101 // If you modify the 'this' pointer's inputs, you should use
1102 // 'set_req'.  If you are making a new Node (either as the new root or
1103 // some new internal piece) you may use 'init_req' to set the initial
1104 // value.  You can make a new Node with either 'new' or 'clone'.  In
1105 // either case, def-use info is correctly maintained.
1106 //
1107 // Example: reshape "(X+3)+4" into "X+7":
1108 //    set_req(1, in(1)->in(1));
1109 //    set_req(2, phase->intcon(7));
1110 //    return this;
1111 // Example: reshape "X*4" into "X<<2"
1112 //    return new LShiftINode(in(1), phase->intcon(2));
1113 //
1114 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1115 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1116 //    Node *shift=phase->transform(new LShiftINode(in(1),phase->intcon(5)));
1117 //    return new AddINode(shift, in(1));
1118 //
1119 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1120 // These forms are faster than 'phase->transform(new ConNode())' and Do
1121 // The Right Thing with def-use info.
1122 //
1123 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1124 // graph uses the 'this' Node it must be the root.  If you want a Node with
1125 // the same Opcode as the 'this' pointer use 'clone'.
1126 //
1127 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1128   return NULL;                  // Default to being Ideal already
1129 }
1130 
1131 // Some nodes have specific Ideal subgraph transformations only if they are
1132 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1133 // for the transformations to happen.
1134 bool Node::has_special_unique_user() const {
1135   assert(outcnt() == 1, "match only for unique out");
1136   Node* n = unique_out();
1137   int op  = Opcode();
1138   if (this->is_Store()) {
1139     // Condition for back-to-back stores folding.
1140     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1141   } else if (this->is_Load() || this->is_DecodeN() || this->is_Phi()) {
1142     // Condition for removing an unused LoadNode or DecodeNNode from the MemBarAcquire precedence input
1143     return n->Opcode() == Op_MemBarAcquire;
1144   } else if (op == Op_AddL) {
1145     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1146     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1147   } else if (op == Op_SubI || op == Op_SubL) {
1148     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1149     return n->Opcode() == op && n->in(2) == this;
1150   } else if (is_If() && (n->is_IfFalse() || n->is_IfTrue())) {
1151     // See IfProjNode::Identity()
1152     return true;
1153   } else {
1154     return BarrierSet::barrier_set()->barrier_set_c2()->has_special_unique_user(this);
1155   }
1156 };
1157 
1158 //--------------------------find_exact_control---------------------------------
1159 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1160 Node* Node::find_exact_control(Node* ctrl) {
1161   if (ctrl == NULL && this->is_Region())
1162     ctrl = this->as_Region()->is_copy();
1163 
1164   if (ctrl != NULL && ctrl->is_CatchProj()) {
1165     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1166       ctrl = ctrl->in(0);
1167     if (ctrl != NULL && !ctrl->is_top())
1168       ctrl = ctrl->in(0);
1169   }
1170 
1171   if (ctrl != NULL && ctrl->is_Proj())
1172     ctrl = ctrl->in(0);
1173 
1174   return ctrl;
1175 }
1176 
1177 //--------------------------dominates------------------------------------------
1178 // Helper function for MemNode::all_controls_dominate().
1179 // Check if 'this' control node dominates or equal to 'sub' control node.
1180 // We already know that if any path back to Root or Start reaches 'this',
1181 // then all paths so, so this is a simple search for one example,
1182 // not an exhaustive search for a counterexample.
1183 bool Node::dominates(Node* sub, Node_List &nlist) {
1184   assert(this->is_CFG(), "expecting control");
1185   assert(sub != NULL && sub->is_CFG(), "expecting control");
1186 
1187   // detect dead cycle without regions
1188   int iterations_without_region_limit = DominatorSearchLimit;
1189 
1190   Node* orig_sub = sub;
1191   Node* dom      = this;
1192   bool  met_dom  = false;
1193   nlist.clear();
1194 
1195   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1196   // After seeing 'dom', continue up to Root or Start.
1197   // If we hit a region (backward split point), it may be a loop head.
1198   // Keep going through one of the region's inputs.  If we reach the
1199   // same region again, go through a different input.  Eventually we
1200   // will either exit through the loop head, or give up.
1201   // (If we get confused, break out and return a conservative 'false'.)
1202   while (sub != NULL) {
1203     if (sub->is_top())  break; // Conservative answer for dead code.
1204     if (sub == dom) {
1205       if (nlist.size() == 0) {
1206         // No Region nodes except loops were visited before and the EntryControl
1207         // path was taken for loops: it did not walk in a cycle.
1208         return true;
1209       } else if (met_dom) {
1210         break;          // already met before: walk in a cycle
1211       } else {
1212         // Region nodes were visited. Continue walk up to Start or Root
1213         // to make sure that it did not walk in a cycle.
1214         met_dom = true; // first time meet
1215         iterations_without_region_limit = DominatorSearchLimit; // Reset
1216      }
1217     }
1218     if (sub->is_Start() || sub->is_Root()) {
1219       // Success if we met 'dom' along a path to Start or Root.
1220       // We assume there are no alternative paths that avoid 'dom'.
1221       // (This assumption is up to the caller to ensure!)
1222       return met_dom;
1223     }
1224     Node* up = sub->in(0);
1225     // Normalize simple pass-through regions and projections:
1226     up = sub->find_exact_control(up);
1227     // If sub == up, we found a self-loop.  Try to push past it.
1228     if (sub == up && sub->is_Loop()) {
1229       // Take loop entry path on the way up to 'dom'.
1230       up = sub->in(1); // in(LoopNode::EntryControl);
1231     } else if (sub == up && sub->is_Region() && sub->req() != 3) {
1232       // Always take in(1) path on the way up to 'dom' for clone regions
1233       // (with only one input) or regions which merge > 2 paths
1234       // (usually used to merge fast/slow paths).
1235       up = sub->in(1);
1236     } else if (sub == up && sub->is_Region()) {
1237       // Try both paths for Regions with 2 input paths (it may be a loop head).
1238       // It could give conservative 'false' answer without information
1239       // which region's input is the entry path.
1240       iterations_without_region_limit = DominatorSearchLimit; // Reset
1241 
1242       bool region_was_visited_before = false;
1243       // Was this Region node visited before?
1244       // If so, we have reached it because we accidentally took a
1245       // loop-back edge from 'sub' back into the body of the loop,
1246       // and worked our way up again to the loop header 'sub'.
1247       // So, take the first unexplored path on the way up to 'dom'.
1248       for (int j = nlist.size() - 1; j >= 0; j--) {
1249         intptr_t ni = (intptr_t)nlist.at(j);
1250         Node* visited = (Node*)(ni & ~1);
1251         bool  visited_twice_already = ((ni & 1) != 0);
1252         if (visited == sub) {
1253           if (visited_twice_already) {
1254             // Visited 2 paths, but still stuck in loop body.  Give up.
1255             return false;
1256           }
1257           // The Region node was visited before only once.
1258           // (We will repush with the low bit set, below.)
1259           nlist.remove(j);
1260           // We will find a new edge and re-insert.
1261           region_was_visited_before = true;
1262           break;
1263         }
1264       }
1265 
1266       // Find an incoming edge which has not been seen yet; walk through it.
1267       assert(up == sub, "");
1268       uint skip = region_was_visited_before ? 1 : 0;
1269       for (uint i = 1; i < sub->req(); i++) {
1270         Node* in = sub->in(i);
1271         if (in != NULL && !in->is_top() && in != sub) {
1272           if (skip == 0) {
1273             up = in;
1274             break;
1275           }
1276           --skip;               // skip this nontrivial input
1277         }
1278       }
1279 
1280       // Set 0 bit to indicate that both paths were taken.
1281       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1282     }
1283 
1284     if (up == sub) {
1285       break;    // some kind of tight cycle
1286     }
1287     if (up == orig_sub && met_dom) {
1288       // returned back after visiting 'dom'
1289       break;    // some kind of cycle
1290     }
1291     if (--iterations_without_region_limit < 0) {
1292       break;    // dead cycle
1293     }
1294     sub = up;
1295   }
1296 
1297   // Did not meet Root or Start node in pred. chain.
1298   // Conservative answer for dead code.
1299   return false;
1300 }
1301 
1302 //------------------------------remove_dead_region-----------------------------
1303 // This control node is dead.  Follow the subgraph below it making everything
1304 // using it dead as well.  This will happen normally via the usual IterGVN
1305 // worklist but this call is more efficient.  Do not update use-def info
1306 // inside the dead region, just at the borders.
1307 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1308   // Con's are a popular node to re-hit in the hash table again.
1309   if( dead->is_Con() ) return;
1310 
1311   // Can't put ResourceMark here since igvn->_worklist uses the same arena
1312   // for verify pass with +VerifyOpto and we add/remove elements in it here.
1313   Node_List  nstack(Thread::current()->resource_area());
1314 
1315   Node *top = igvn->C->top();
1316   nstack.push(dead);
1317   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1318 
1319   while (nstack.size() > 0) {
1320     dead = nstack.pop();
1321     if (dead->Opcode() == Op_SafePoint) {
1322       dead->as_SafePoint()->disconnect_from_root(igvn);
1323     }
1324     if (dead->outcnt() > 0) {
1325       // Keep dead node on stack until all uses are processed.
1326       nstack.push(dead);
1327       // For all Users of the Dead...    ;-)
1328       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1329         Node* use = dead->last_out(k);
1330         igvn->hash_delete(use);       // Yank from hash table prior to mod
1331         if (use->in(0) == dead) {     // Found another dead node
1332           assert (!use->is_Con(), "Control for Con node should be Root node.");
1333           use->set_req(0, top);       // Cut dead edge to prevent processing
1334           nstack.push(use);           // the dead node again.
1335         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1336                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1337                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1338           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1339           use->set_req(0, top);       // Cut self edge
1340           nstack.push(use);
1341         } else {                      // Else found a not-dead user
1342           // Dead if all inputs are top or null
1343           bool dead_use = !use->is_Root(); // Keep empty graph alive
1344           for (uint j = 1; j < use->req(); j++) {
1345             Node* in = use->in(j);
1346             if (in == dead) {         // Turn all dead inputs into TOP
1347               use->set_req(j, top);
1348             } else if (in != NULL && !in->is_top()) {
1349               dead_use = false;
1350             }
1351           }
1352           if (dead_use) {
1353             if (use->is_Region()) {
1354               use->set_req(0, top);   // Cut self edge
1355             }
1356             nstack.push(use);
1357           } else {
1358             igvn->_worklist.push(use);
1359           }
1360         }
1361         // Refresh the iterator, since any number of kills might have happened.
1362         k = dead->last_outs(kmin);
1363       }
1364     } else { // (dead->outcnt() == 0)
1365       // Done with outputs.
1366       igvn->hash_delete(dead);
1367       igvn->_worklist.remove(dead);
1368       igvn->C->remove_modified_node(dead);
1369       igvn->set_type(dead, Type::TOP);
1370       if (dead->is_macro()) {
1371         igvn->C->remove_macro_node(dead);
1372       }
1373       if (dead->is_expensive()) {
1374         igvn->C->remove_expensive_node(dead);
1375       }
1376       CastIINode* cast = dead->isa_CastII();
1377       if (cast != NULL && cast->has_range_check()) {
1378         igvn->C->remove_range_check_cast(cast);
1379       }
1380       if (dead->Opcode() == Op_Opaque4) {
1381         igvn->C->remove_opaque4_node(dead);
1382       }
1383       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1384       bs->unregister_potential_barrier_node(dead);
1385       igvn->C->record_dead_node(dead->_idx);
1386       // Kill all inputs to the dead guy
1387       for (uint i=0; i < dead->req(); i++) {
1388         Node *n = dead->in(i);      // Get input to dead guy
1389         if (n != NULL && !n->is_top()) { // Input is valid?
1390           dead->set_req(i, top);    // Smash input away
1391           if (n->outcnt() == 0) {   // Input also goes dead?
1392             if (!n->is_Con())
1393               nstack.push(n);       // Clear it out as well
1394           } else if (n->outcnt() == 1 &&
1395                      n->has_special_unique_user()) {
1396             igvn->add_users_to_worklist( n );
1397           } else if (n->outcnt() <= 2 && n->is_Store()) {
1398             // Push store's uses on worklist to enable folding optimization for
1399             // store/store and store/load to the same address.
1400             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1401             // and remove_globally_dead_node().
1402             igvn->add_users_to_worklist( n );
1403           } else {
1404             BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, 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 bool Node::cmp( const Node &n ) const {
1444   return true;                  // 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   }
1462   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1463   if (!bs->needs_anti_dependence_check(this)) {
1464     return false;
1465   }
1466   return in(1)->bottom_type()->has_memory();
1467 }
1468 
1469 // Get an integer constant from a ConNode (or CastIINode).
1470 // Return a default value if there is no apparent constant here.
1471 const TypeInt* Node::find_int_type() const {
1472   if (this->is_Type()) {
1473     return this->as_Type()->type()->isa_int();
1474   } else if (this->is_Con()) {
1475     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1476     return this->bottom_type()->isa_int();
1477   }
1478   return NULL;
1479 }
1480 
1481 // Get a pointer constant from a ConstNode.
1482 // Returns the constant if it is a pointer ConstNode
1483 intptr_t Node::get_ptr() const {
1484   assert( Opcode() == Op_ConP, "" );
1485   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1486 }
1487 
1488 // Get a narrow oop constant from a ConNNode.
1489 intptr_t Node::get_narrowcon() const {
1490   assert( Opcode() == Op_ConN, "" );
1491   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1492 }
1493 
1494 // Get a long constant from a ConNode.
1495 // Return a default value if there is no apparent constant here.
1496 const TypeLong* Node::find_long_type() const {
1497   if (this->is_Type()) {
1498     return this->as_Type()->type()->isa_long();
1499   } else if (this->is_Con()) {
1500     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1501     return this->bottom_type()->isa_long();
1502   }
1503   return NULL;
1504 }
1505 
1506 
1507 /**
1508  * Return a ptr type for nodes which should have it.
1509  */
1510 const TypePtr* Node::get_ptr_type() const {
1511   const TypePtr* tp = this->bottom_type()->make_ptr();
1512 #ifdef ASSERT
1513   if (tp == NULL) {
1514     this->dump(1);
1515     assert((tp != NULL), "unexpected node type");
1516   }
1517 #endif
1518   return tp;
1519 }
1520 
1521 // Get a double constant from a ConstNode.
1522 // Returns the constant if it is a double ConstNode
1523 jdouble Node::getd() const {
1524   assert( Opcode() == Op_ConD, "" );
1525   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1526 }
1527 
1528 // Get a float constant from a ConstNode.
1529 // Returns the constant if it is a float ConstNode
1530 jfloat Node::getf() const {
1531   assert( Opcode() == Op_ConF, "" );
1532   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1533 }
1534 
1535 #ifndef PRODUCT
1536 
1537 //------------------------------find------------------------------------------
1538 // Find a neighbor of this Node with the given _idx
1539 // If idx is negative, find its absolute value, following both _in and _out.
1540 static void find_recur(Compile* C,  Node* &result, Node *n, int idx, bool only_ctrl,
1541                         VectorSet* old_space, VectorSet* new_space ) {
1542   int node_idx = (idx >= 0) ? idx : -idx;
1543   if (NotANode(n))  return;  // Gracefully handle NULL, -1, 0xabababab, etc.
1544   // Contained in new_space or old_space?   Check old_arena first since it's mostly empty.
1545   VectorSet *v = C->old_arena()->contains(n) ? old_space : new_space;
1546   if( v->test(n->_idx) ) return;
1547   if( (int)n->_idx == node_idx
1548       debug_only(|| n->debug_idx() == node_idx) ) {
1549     if (result != NULL)
1550       tty->print("find: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1551                  (uintptr_t)result, (uintptr_t)n, node_idx);
1552     result = n;
1553   }
1554   v->set(n->_idx);
1555   for( uint i=0; i<n->len(); i++ ) {
1556     if( only_ctrl && !(n->is_Region()) && (n->Opcode() != Op_Root) && (i != TypeFunc::Control) ) continue;
1557     find_recur(C, result, n->in(i), idx, only_ctrl, old_space, new_space );
1558   }
1559   // Search along forward edges also:
1560   if (idx < 0 && !only_ctrl) {
1561     for( uint j=0; j<n->outcnt(); j++ ) {
1562       find_recur(C, result, n->raw_out(j), idx, only_ctrl, old_space, new_space );
1563     }
1564   }
1565 #ifdef ASSERT
1566   // Search along debug_orig edges last, checking for cycles
1567   Node* orig = n->debug_orig();
1568   if (orig != NULL) {
1569     do {
1570       if (NotANode(orig))  break;
1571       find_recur(C, result, orig, idx, only_ctrl, old_space, new_space );
1572       orig = orig->debug_orig();
1573     } while (orig != NULL && orig != n->debug_orig());
1574   }
1575 #endif //ASSERT
1576 }
1577 
1578 // call this from debugger:
1579 Node* find_node(Node* n, int idx) {
1580   return n->find(idx);
1581 }
1582 
1583 //------------------------------find-------------------------------------------
1584 Node* Node::find(int idx) const {
1585   ResourceArea *area = Thread::current()->resource_area();
1586   VectorSet old_space(area), new_space(area);
1587   Node* result = NULL;
1588   find_recur(Compile::current(), result, (Node*) this, idx, false, &old_space, &new_space );
1589   return result;
1590 }
1591 
1592 //------------------------------find_ctrl--------------------------------------
1593 // Find an ancestor to this node in the control history with given _idx
1594 Node* Node::find_ctrl(int idx) const {
1595   ResourceArea *area = Thread::current()->resource_area();
1596   VectorSet old_space(area), new_space(area);
1597   Node* result = NULL;
1598   find_recur(Compile::current(), result, (Node*) this, idx, true, &old_space, &new_space );
1599   return result;
1600 }
1601 #endif
1602 
1603 
1604 
1605 #ifndef PRODUCT
1606 
1607 // -----------------------------Name-------------------------------------------
1608 extern const char *NodeClassNames[];
1609 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
1610 
1611 static bool is_disconnected(const Node* n) {
1612   for (uint i = 0; i < n->req(); i++) {
1613     if (n->in(i) != NULL)  return false;
1614   }
1615   return true;
1616 }
1617 
1618 #ifdef ASSERT
1619 static void dump_orig(Node* orig, outputStream *st) {
1620   Compile* C = Compile::current();
1621   if (NotANode(orig)) orig = NULL;
1622   if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1623   if (orig == NULL) return;
1624   st->print(" !orig=");
1625   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
1626   if (NotANode(fast)) fast = NULL;
1627   while (orig != NULL) {
1628     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
1629     if (discon) st->print("[");
1630     if (!Compile::current()->node_arena()->contains(orig))
1631       st->print("o");
1632     st->print("%d", orig->_idx);
1633     if (discon) st->print("]");
1634     orig = orig->debug_orig();
1635     if (NotANode(orig)) orig = NULL;
1636     if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1637     if (orig != NULL) st->print(",");
1638     if (fast != NULL) {
1639       // Step fast twice for each single step of orig:
1640       fast = fast->debug_orig();
1641       if (NotANode(fast)) fast = NULL;
1642       if (fast != NULL && fast != orig) {
1643         fast = fast->debug_orig();
1644         if (NotANode(fast)) fast = NULL;
1645       }
1646       if (fast == orig) {
1647         st->print("...");
1648         break;
1649       }
1650     }
1651   }
1652 }
1653 
1654 void Node::set_debug_orig(Node* orig) {
1655   _debug_orig = orig;
1656   if (BreakAtNode == 0)  return;
1657   if (NotANode(orig))  orig = NULL;
1658   int trip = 10;
1659   while (orig != NULL) {
1660     if (orig->debug_idx() == BreakAtNode || (int)orig->_idx == BreakAtNode) {
1661       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d orig._idx=%d orig._debug_idx=%d",
1662                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
1663       BREAKPOINT;
1664     }
1665     orig = orig->debug_orig();
1666     if (NotANode(orig))  orig = NULL;
1667     if (trip-- <= 0)  break;
1668   }
1669 }
1670 #endif //ASSERT
1671 
1672 //------------------------------dump------------------------------------------
1673 // Dump a Node
1674 void Node::dump(const char* suffix, bool mark, outputStream *st) const {
1675   Compile* C = Compile::current();
1676   bool is_new = C->node_arena()->contains(this);
1677   C->_in_dump_cnt++;
1678   st->print("%c%d%s\t%s\t=== ", is_new ? ' ' : 'o', _idx, mark ? " >" : "", Name());
1679 
1680   // Dump the required and precedence inputs
1681   dump_req(st);
1682   dump_prec(st);
1683   // Dump the outputs
1684   dump_out(st);
1685 
1686   if (is_disconnected(this)) {
1687 #ifdef ASSERT
1688     st->print("  [%d]",debug_idx());
1689     dump_orig(debug_orig(), st);
1690 #endif
1691     st->cr();
1692     C->_in_dump_cnt--;
1693     return;                     // don't process dead nodes
1694   }
1695 
1696   if (C->clone_map().value(_idx) != 0) {
1697     C->clone_map().dump(_idx);
1698   }
1699   // Dump node-specific info
1700   dump_spec(st);
1701 #ifdef ASSERT
1702   // Dump the non-reset _debug_idx
1703   if (Verbose && WizardMode) {
1704     st->print("  [%d]",debug_idx());
1705   }
1706 #endif
1707 
1708   const Type *t = bottom_type();
1709 
1710   if (t != NULL && (t->isa_instptr() || t->isa_klassptr())) {
1711     const TypeInstPtr  *toop = t->isa_instptr();
1712     const TypeKlassPtr *tkls = t->isa_klassptr();
1713     ciKlass*           klass = toop ? toop->klass() : (tkls ? tkls->klass() : NULL );
1714     if (klass && klass->is_loaded() && klass->is_interface()) {
1715       st->print("  Interface:");
1716     } else if (toop) {
1717       st->print("  Oop:");
1718     } else if (tkls) {
1719       st->print("  Klass:");
1720     }
1721     t->dump_on(st);
1722   } else if (t == Type::MEMORY) {
1723     st->print("  Memory:");
1724     MemNode::dump_adr_type(this, adr_type(), st);
1725   } else if (Verbose || WizardMode) {
1726     st->print("  Type:");
1727     if (t) {
1728       t->dump_on(st);
1729     } else {
1730       st->print("no type");
1731     }
1732   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
1733     // Dump MachSpillcopy vector type.
1734     t->dump_on(st);
1735   }
1736   if (is_new) {
1737     debug_only(dump_orig(debug_orig(), st));
1738     Node_Notes* nn = C->node_notes_at(_idx);
1739     if (nn != NULL && !nn->is_clear()) {
1740       if (nn->jvms() != NULL) {
1741         st->print(" !jvms:");
1742         nn->jvms()->dump_spec(st);
1743       }
1744     }
1745   }
1746   if (suffix) st->print("%s", suffix);
1747   C->_in_dump_cnt--;
1748 }
1749 
1750 //------------------------------dump_req--------------------------------------
1751 void Node::dump_req(outputStream *st) const {
1752   // Dump the required input edges
1753   for (uint i = 0; i < req(); i++) {    // For all required inputs
1754     Node* d = in(i);
1755     if (d == NULL) {
1756       st->print("_ ");
1757     } else if (NotANode(d)) {
1758       st->print("NotANode ");  // uninitialized, sentinel, garbage, etc.
1759     } else {
1760       st->print("%c%d ", Compile::current()->node_arena()->contains(d) ? ' ' : 'o', d->_idx);
1761     }
1762   }
1763 }
1764 
1765 
1766 //------------------------------dump_prec-------------------------------------
1767 void Node::dump_prec(outputStream *st) const {
1768   // Dump the precedence edges
1769   int any_prec = 0;
1770   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
1771     Node* p = in(i);
1772     if (p != NULL) {
1773       if (!any_prec++) st->print(" |");
1774       if (NotANode(p)) { st->print("NotANode "); continue; }
1775       st->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
1776     }
1777   }
1778 }
1779 
1780 //------------------------------dump_out--------------------------------------
1781 void Node::dump_out(outputStream *st) const {
1782   // Delimit the output edges
1783   st->print(" [[");
1784   // Dump the output edges
1785   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
1786     Node* u = _out[i];
1787     if (u == NULL) {
1788       st->print("_ ");
1789     } else if (NotANode(u)) {
1790       st->print("NotANode ");
1791     } else {
1792       st->print("%c%d ", Compile::current()->node_arena()->contains(u) ? ' ' : 'o', u->_idx);
1793     }
1794   }
1795   st->print("]] ");
1796 }
1797 
1798 //----------------------------collect_nodes_i----------------------------------
1799 // Collects nodes from an Ideal graph, starting from a given start node and
1800 // moving in a given direction until a certain depth (distance from the start
1801 // node) is reached. Duplicates are ignored.
1802 // Arguments:
1803 //   nstack:        the nodes are collected into this array.
1804 //   start:         the node at which to start collecting.
1805 //   direction:     if this is a positive number, collect input nodes; if it is
1806 //                  a negative number, collect output nodes.
1807 //   depth:         collect nodes up to this distance from the start node.
1808 //   include_start: whether to include the start node in the result collection.
1809 //   only_ctrl:     whether to regard control edges only during traversal.
1810 //   only_data:     whether to regard data edges only during traversal.
1811 static void collect_nodes_i(GrowableArray<Node*> *nstack, const Node* start, int direction, uint depth, bool include_start, bool only_ctrl, bool only_data) {
1812   Node* s = (Node*) start; // remove const
1813   nstack->append(s);
1814   int begin = 0;
1815   int end = 0;
1816   for(uint i = 0; i < depth; i++) {
1817     end = nstack->length();
1818     for(int j = begin; j < end; j++) {
1819       Node* tp  = nstack->at(j);
1820       uint limit = direction > 0 ? tp->len() : tp->outcnt();
1821       for(uint k = 0; k < limit; k++) {
1822         Node* n = direction > 0 ? tp->in(k) : tp->raw_out(k);
1823 
1824         if (NotANode(n))  continue;
1825         // do not recurse through top or the root (would reach unrelated stuff)
1826         if (n->is_Root() || n->is_top()) continue;
1827         if (only_ctrl && !n->is_CFG()) continue;
1828         if (only_data && n->is_CFG()) continue;
1829 
1830         bool on_stack = nstack->contains(n);
1831         if (!on_stack) {
1832           nstack->append(n);
1833         }
1834       }
1835     }
1836     begin = end;
1837   }
1838   if (!include_start) {
1839     nstack->remove(s);
1840   }
1841 }
1842 
1843 //------------------------------dump_nodes-------------------------------------
1844 static void dump_nodes(const Node* start, int d, bool only_ctrl) {
1845   if (NotANode(start)) return;
1846 
1847   GrowableArray <Node *> nstack(Compile::current()->live_nodes());
1848   collect_nodes_i(&nstack, start, d, (uint) ABS(d), true, only_ctrl, false);
1849 
1850   int end = nstack.length();
1851   if (d > 0) {
1852     for(int j = end-1; j >= 0; j--) {
1853       nstack.at(j)->dump();
1854     }
1855   } else {
1856     for(int j = 0; j < end; j++) {
1857       nstack.at(j)->dump();
1858     }
1859   }
1860 }
1861 
1862 //------------------------------dump-------------------------------------------
1863 void Node::dump(int d) const {
1864   dump_nodes(this, d, false);
1865 }
1866 
1867 //------------------------------dump_ctrl--------------------------------------
1868 // Dump a Node's control history to depth
1869 void Node::dump_ctrl(int d) const {
1870   dump_nodes(this, d, true);
1871 }
1872 
1873 //-----------------------------dump_compact------------------------------------
1874 void Node::dump_comp() const {
1875   this->dump_comp("\n");
1876 }
1877 
1878 //-----------------------------dump_compact------------------------------------
1879 // Dump a Node in compact representation, i.e., just print its name and index.
1880 // Nodes can specify additional specifics to print in compact representation by
1881 // implementing dump_compact_spec.
1882 void Node::dump_comp(const char* suffix, outputStream *st) const {
1883   Compile* C = Compile::current();
1884   C->_in_dump_cnt++;
1885   st->print("%s(%d)", Name(), _idx);
1886   this->dump_compact_spec(st);
1887   if (suffix) {
1888     st->print("%s", suffix);
1889   }
1890   C->_in_dump_cnt--;
1891 }
1892 
1893 //----------------------------dump_related-------------------------------------
1894 // Dump a Node's related nodes - the notion of "related" depends on the Node at
1895 // hand and is determined by the implementation of the virtual method rel.
1896 void Node::dump_related() const {
1897   Compile* C = Compile::current();
1898   GrowableArray <Node *> in_rel(C->unique());
1899   GrowableArray <Node *> out_rel(C->unique());
1900   this->related(&in_rel, &out_rel, false);
1901   for (int i = in_rel.length() - 1; i >= 0; i--) {
1902     in_rel.at(i)->dump();
1903   }
1904   this->dump("\n", true);
1905   for (int i = 0; i < out_rel.length(); i++) {
1906     out_rel.at(i)->dump();
1907   }
1908 }
1909 
1910 //----------------------------dump_related-------------------------------------
1911 // Dump a Node's related nodes up to a given depth (distance from the start
1912 // node).
1913 // Arguments:
1914 //   d_in:  depth for input nodes.
1915 //   d_out: depth for output nodes (note: this also is a positive number).
1916 void Node::dump_related(uint d_in, uint d_out) const {
1917   Compile* C = Compile::current();
1918   GrowableArray <Node *> in_rel(C->unique());
1919   GrowableArray <Node *> out_rel(C->unique());
1920 
1921   // call collect_nodes_i directly
1922   collect_nodes_i(&in_rel, this, 1, d_in, false, false, false);
1923   collect_nodes_i(&out_rel, this, -1, d_out, false, false, false);
1924 
1925   for (int i = in_rel.length() - 1; i >= 0; i--) {
1926     in_rel.at(i)->dump();
1927   }
1928   this->dump("\n", true);
1929   for (int i = 0; i < out_rel.length(); i++) {
1930     out_rel.at(i)->dump();
1931   }
1932 }
1933 
1934 //------------------------dump_related_compact---------------------------------
1935 // Dump a Node's related nodes in compact representation. The notion of
1936 // "related" depends on the Node at hand and is determined by the implementation
1937 // of the virtual method rel.
1938 void Node::dump_related_compact() const {
1939   Compile* C = Compile::current();
1940   GrowableArray <Node *> in_rel(C->unique());
1941   GrowableArray <Node *> out_rel(C->unique());
1942   this->related(&in_rel, &out_rel, true);
1943   int n_in = in_rel.length();
1944   int n_out = out_rel.length();
1945 
1946   this->dump_comp(n_in == 0 ? "\n" : "  ");
1947   for (int i = 0; i < n_in; i++) {
1948     in_rel.at(i)->dump_comp(i == n_in - 1 ? "\n" : "  ");
1949   }
1950   for (int i = 0; i < n_out; i++) {
1951     out_rel.at(i)->dump_comp(i == n_out - 1 ? "\n" : "  ");
1952   }
1953 }
1954 
1955 //------------------------------related----------------------------------------
1956 // Collect a Node's related nodes. The default behaviour just collects the
1957 // inputs and outputs at depth 1, including both control and data flow edges,
1958 // regardless of whether the presentation is compact or not. For data nodes,
1959 // the default is to collect all data inputs (till level 1 if compact), and
1960 // outputs till level 1.
1961 void Node::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
1962   if (this->is_CFG()) {
1963     collect_nodes_i(in_rel, this, 1, 1, false, false, false);
1964     collect_nodes_i(out_rel, this, -1, 1, false, false, false);
1965   } else {
1966     if (compact) {
1967       this->collect_nodes(in_rel, 1, false, true);
1968     } else {
1969       this->collect_nodes_in_all_data(in_rel, false);
1970     }
1971     this->collect_nodes(out_rel, -1, false, false);
1972   }
1973 }
1974 
1975 //---------------------------collect_nodes-------------------------------------
1976 // An entry point to the low-level node collection facility, to start from a
1977 // given node in the graph. The start node is by default not included in the
1978 // result.
1979 // Arguments:
1980 //   ns:   collect the nodes into this data structure.
1981 //   d:    the depth (distance from start node) to which nodes should be
1982 //         collected. A value >0 indicates input nodes, a value <0, output
1983 //         nodes.
1984 //   ctrl: include only control nodes.
1985 //   data: include only data nodes.
1986 void Node::collect_nodes(GrowableArray<Node*> *ns, int d, bool ctrl, bool data) const {
1987   if (ctrl && data) {
1988     // ignore nonsensical combination
1989     return;
1990   }
1991   collect_nodes_i(ns, this, d, (uint) ABS(d), false, ctrl, data);
1992 }
1993 
1994 //--------------------------collect_nodes_in-----------------------------------
1995 static void collect_nodes_in(Node* start, GrowableArray<Node*> *ns, bool primary_is_data, bool collect_secondary) {
1996   // The maximum depth is determined using a BFS that visits all primary (data
1997   // or control) inputs and increments the depth at each level.
1998   uint d_in = 0;
1999   GrowableArray<Node*> nodes(Compile::current()->unique());
2000   nodes.push(start);
2001   int nodes_at_current_level = 1;
2002   int n_idx = 0;
2003   while (nodes_at_current_level > 0) {
2004     // Add all primary inputs reachable from the current level to the list, and
2005     // increase the depth if there were any.
2006     int nodes_at_next_level = 0;
2007     bool nodes_added = false;
2008     while (nodes_at_current_level > 0) {
2009       nodes_at_current_level--;
2010       Node* current = nodes.at(n_idx++);
2011       for (uint i = 0; i < current->len(); i++) {
2012         Node* n = current->in(i);
2013         if (NotANode(n)) {
2014           continue;
2015         }
2016         if ((primary_is_data && n->is_CFG()) || (!primary_is_data && !n->is_CFG())) {
2017           continue;
2018         }
2019         if (!nodes.contains(n)) {
2020           nodes.push(n);
2021           nodes_added = true;
2022           nodes_at_next_level++;
2023         }
2024       }
2025     }
2026     if (nodes_added) {
2027       d_in++;
2028     }
2029     nodes_at_current_level = nodes_at_next_level;
2030   }
2031   start->collect_nodes(ns, d_in, !primary_is_data, primary_is_data);
2032   if (collect_secondary) {
2033     // Now, iterate over the secondary nodes in ns and add the respective
2034     // boundary reachable from them.
2035     GrowableArray<Node*> sns(Compile::current()->unique());
2036     for (GrowableArrayIterator<Node*> it = ns->begin(); it != ns->end(); ++it) {
2037       Node* n = *it;
2038       n->collect_nodes(&sns, 1, primary_is_data, !primary_is_data);
2039       for (GrowableArrayIterator<Node*> d = sns.begin(); d != sns.end(); ++d) {
2040         ns->append_if_missing(*d);
2041       }
2042       sns.clear();
2043     }
2044   }
2045 }
2046 
2047 //---------------------collect_nodes_in_all_data-------------------------------
2048 // Collect the entire data input graph. Include the control boundary if
2049 // requested.
2050 // Arguments:
2051 //   ns:   collect the nodes into this data structure.
2052 //   ctrl: if true, include the control boundary.
2053 void Node::collect_nodes_in_all_data(GrowableArray<Node*> *ns, bool ctrl) const {
2054   collect_nodes_in((Node*) this, ns, true, ctrl);
2055 }
2056 
2057 //--------------------------collect_nodes_in_all_ctrl--------------------------
2058 // Collect the entire control input graph. Include the data boundary if
2059 // requested.
2060 //   ns:   collect the nodes into this data structure.
2061 //   data: if true, include the control boundary.
2062 void Node::collect_nodes_in_all_ctrl(GrowableArray<Node*> *ns, bool data) const {
2063   collect_nodes_in((Node*) this, ns, false, data);
2064 }
2065 
2066 //------------------collect_nodes_out_all_ctrl_boundary------------------------
2067 // Collect the entire output graph until hitting control node boundaries, and
2068 // include those.
2069 void Node::collect_nodes_out_all_ctrl_boundary(GrowableArray<Node*> *ns) const {
2070   // Perform a BFS and stop at control nodes.
2071   GrowableArray<Node*> nodes(Compile::current()->unique());
2072   nodes.push((Node*) this);
2073   while (nodes.length() > 0) {
2074     Node* current = nodes.pop();
2075     if (NotANode(current)) {
2076       continue;
2077     }
2078     ns->append_if_missing(current);
2079     if (!current->is_CFG()) {
2080       for (DUIterator i = current->outs(); current->has_out(i); i++) {
2081         nodes.push(current->out(i));
2082       }
2083     }
2084   }
2085   ns->remove((Node*) this);
2086 }
2087 
2088 // VERIFICATION CODE
2089 // For each input edge to a node (ie - for each Use-Def edge), verify that
2090 // there is a corresponding Def-Use edge.
2091 //------------------------------verify_edges-----------------------------------
2092 void Node::verify_edges(Unique_Node_List &visited) {
2093   uint i, j, idx;
2094   int  cnt;
2095   Node *n;
2096 
2097   // Recursive termination test
2098   if (visited.member(this))  return;
2099   visited.push(this);
2100 
2101   // Walk over all input edges, checking for correspondence
2102   for( i = 0; i < len(); i++ ) {
2103     n = in(i);
2104     if (n != NULL && !n->is_top()) {
2105       // Count instances of (Node *)this
2106       cnt = 0;
2107       for (idx = 0; idx < n->_outcnt; idx++ ) {
2108         if (n->_out[idx] == (Node *)this)  cnt++;
2109       }
2110       assert( cnt > 0,"Failed to find Def-Use edge." );
2111       // Check for duplicate edges
2112       // walk the input array downcounting the input edges to n
2113       for( j = 0; j < len(); j++ ) {
2114         if( in(j) == n ) cnt--;
2115       }
2116       assert( cnt == 0,"Mismatched edge count.");
2117     } else if (n == NULL) {
2118       assert(i >= req() || i == 0 || is_Region() || is_Phi(), "only regions or phis have null data edges");
2119     } else {
2120       assert(n->is_top(), "sanity");
2121       // Nothing to check.
2122     }
2123   }
2124   // Recursive walk over all input edges
2125   for( i = 0; i < len(); i++ ) {
2126     n = in(i);
2127     if( n != NULL )
2128       in(i)->verify_edges(visited);
2129   }
2130 }
2131 
2132 //------------------------------verify_recur-----------------------------------
2133 static const Node *unique_top = NULL;
2134 
2135 void Node::verify_recur(const Node *n, int verify_depth,
2136                         VectorSet &old_space, VectorSet &new_space) {
2137   if ( verify_depth == 0 )  return;
2138   if (verify_depth > 0)  --verify_depth;
2139 
2140   Compile* C = Compile::current();
2141 
2142   // Contained in new_space or old_space?
2143   VectorSet *v = C->node_arena()->contains(n) ? &new_space : &old_space;
2144   // Check for visited in the proper space.  Numberings are not unique
2145   // across spaces so we need a separate VectorSet for each space.
2146   if( v->test_set(n->_idx) ) return;
2147 
2148   if (n->is_Con() && n->bottom_type() == Type::TOP) {
2149     if (C->cached_top_node() == NULL)
2150       C->set_cached_top_node((Node*)n);
2151     assert(C->cached_top_node() == n, "TOP node must be unique");
2152   }
2153 
2154   for( uint i = 0; i < n->len(); i++ ) {
2155     Node *x = n->in(i);
2156     if (!x || x->is_top()) continue;
2157 
2158     // Verify my input has a def-use edge to me
2159     if (true /*VerifyDefUse*/) {
2160       // Count use-def edges from n to x
2161       int cnt = 0;
2162       for( uint j = 0; j < n->len(); j++ )
2163         if( n->in(j) == x )
2164           cnt++;
2165       // Count def-use edges from x to n
2166       uint max = x->_outcnt;
2167       for( uint k = 0; k < max; k++ )
2168         if (x->_out[k] == n)
2169           cnt--;
2170       assert( cnt == 0, "mismatched def-use edge counts" );
2171     }
2172 
2173     verify_recur(x, verify_depth, old_space, new_space);
2174   }
2175 
2176 }
2177 
2178 //------------------------------verify-----------------------------------------
2179 // Check Def-Use info for my subgraph
2180 void Node::verify() const {
2181   Compile* C = Compile::current();
2182   Node* old_top = C->cached_top_node();
2183   ResourceMark rm;
2184   ResourceArea *area = Thread::current()->resource_area();
2185   VectorSet old_space(area), new_space(area);
2186   verify_recur(this, -1, old_space, new_space);
2187   C->set_cached_top_node(old_top);
2188 }
2189 #endif
2190 
2191 
2192 //------------------------------walk-------------------------------------------
2193 // Graph walk, with both pre-order and post-order functions
2194 void Node::walk(NFunc pre, NFunc post, void *env) {
2195   VectorSet visited(Thread::current()->resource_area()); // Setup for local walk
2196   walk_(pre, post, env, visited);
2197 }
2198 
2199 void Node::walk_(NFunc pre, NFunc post, void *env, VectorSet &visited) {
2200   if( visited.test_set(_idx) ) return;
2201   pre(*this,env);               // Call the pre-order walk function
2202   for( uint i=0; i<_max; i++ )
2203     if( in(i) )                 // Input exists and is not walked?
2204       in(i)->walk_(pre,post,env,visited); // Walk it with pre & post functions
2205   post(*this,env);              // Call the post-order walk function
2206 }
2207 
2208 void Node::nop(Node &, void*) {}
2209 
2210 //------------------------------Registers--------------------------------------
2211 // Do we Match on this edge index or not?  Generally false for Control
2212 // and true for everything else.  Weird for calls & returns.
2213 uint Node::match_edge(uint idx) const {
2214   return idx;                   // True for other than index 0 (control)
2215 }
2216 
2217 static RegMask _not_used_at_all;
2218 // Register classes are defined for specific machines
2219 const RegMask &Node::out_RegMask() const {
2220   ShouldNotCallThis();
2221   return _not_used_at_all;
2222 }
2223 
2224 const RegMask &Node::in_RegMask(uint) const {
2225   ShouldNotCallThis();
2226   return _not_used_at_all;
2227 }
2228 
2229 //=============================================================================
2230 //-----------------------------------------------------------------------------
2231 void Node_Array::reset( Arena *new_arena ) {
2232   _a->Afree(_nodes,_max*sizeof(Node*));
2233   _max   = 0;
2234   _nodes = NULL;
2235   _a     = new_arena;
2236 }
2237 
2238 //------------------------------clear------------------------------------------
2239 // Clear all entries in _nodes to NULL but keep storage
2240 void Node_Array::clear() {
2241   Copy::zero_to_bytes( _nodes, _max*sizeof(Node*) );
2242 }
2243 
2244 //-----------------------------------------------------------------------------
2245 void Node_Array::grow( uint i ) {
2246   if( !_max ) {
2247     _max = 1;
2248     _nodes = (Node**)_a->Amalloc( _max * sizeof(Node*) );
2249     _nodes[0] = NULL;
2250   }
2251   uint old = _max;
2252   while( i >= _max ) _max <<= 1;        // Double to fit
2253   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2254   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2255 }
2256 
2257 //-----------------------------------------------------------------------------
2258 void Node_Array::insert( uint i, Node *n ) {
2259   if( _nodes[_max-1] ) grow(_max);      // Get more space if full
2260   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i+1], ((_max-i-1)*sizeof(Node*)));
2261   _nodes[i] = n;
2262 }
2263 
2264 //-----------------------------------------------------------------------------
2265 void Node_Array::remove( uint i ) {
2266   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i+1], (HeapWord*)&_nodes[i], ((_max-i-1)*sizeof(Node*)));
2267   _nodes[_max-1] = NULL;
2268 }
2269 
2270 //-----------------------------------------------------------------------------
2271 void Node_Array::sort( C_sort_func_t func) {
2272   qsort( _nodes, _max, sizeof( Node* ), func );
2273 }
2274 
2275 //-----------------------------------------------------------------------------
2276 void Node_Array::dump() const {
2277 #ifndef PRODUCT
2278   for( uint i = 0; i < _max; i++ ) {
2279     Node *nn = _nodes[i];
2280     if( nn != NULL ) {
2281       tty->print("%5d--> ",i); nn->dump();
2282     }
2283   }
2284 #endif
2285 }
2286 
2287 //--------------------------is_iteratively_computed------------------------------
2288 // Operation appears to be iteratively computed (such as an induction variable)
2289 // It is possible for this operation to return false for a loop-varying
2290 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2291 bool Node::is_iteratively_computed() {
2292   if (ideal_reg()) { // does operation have a result register?
2293     for (uint i = 1; i < req(); i++) {
2294       Node* n = in(i);
2295       if (n != NULL && n->is_Phi()) {
2296         for (uint j = 1; j < n->req(); j++) {
2297           if (n->in(j) == this) {
2298             return true;
2299           }
2300         }
2301       }
2302     }
2303   }
2304   return false;
2305 }
2306 
2307 //--------------------------find_similar------------------------------
2308 // Return a node with opcode "opc" and same inputs as "this" if one can
2309 // be found; Otherwise return NULL;
2310 Node* Node::find_similar(int opc) {
2311   if (req() >= 2) {
2312     Node* def = in(1);
2313     if (def && def->outcnt() >= 2) {
2314       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2315         Node* use = def->fast_out(i);
2316         if (use != this &&
2317             use->Opcode() == opc &&
2318             use->req() == req()) {
2319           uint j;
2320           for (j = 0; j < use->req(); j++) {
2321             if (use->in(j) != in(j)) {
2322               break;
2323             }
2324           }
2325           if (j == use->req()) {
2326             return use;
2327           }
2328         }
2329       }
2330     }
2331   }
2332   return NULL;
2333 }
2334 
2335 
2336 //--------------------------unique_ctrl_out------------------------------
2337 // Return the unique control out if only one. Null if none or more than one.
2338 Node* Node::unique_ctrl_out() const {
2339   Node* found = NULL;
2340   for (uint i = 0; i < outcnt(); i++) {
2341     Node* use = raw_out(i);
2342     if (use->is_CFG() && use != this) {
2343       if (found != NULL) return NULL;
2344       found = use;
2345     }
2346   }
2347   return found;
2348 }
2349 
2350 void Node::ensure_control_or_add_prec(Node* c) {
2351   if (in(0) == NULL) {
2352     set_req(0, c);
2353   } else if (in(0) != c) {
2354     add_prec(c);
2355   }
2356 }
2357 
2358 //=============================================================================
2359 //------------------------------yank-------------------------------------------
2360 // Find and remove
2361 void Node_List::yank( Node *n ) {
2362   uint i;
2363   for( i = 0; i < _cnt; i++ )
2364     if( _nodes[i] == n )
2365       break;
2366 
2367   if( i < _cnt )
2368     _nodes[i] = _nodes[--_cnt];
2369 }
2370 
2371 //------------------------------dump-------------------------------------------
2372 void Node_List::dump() const {
2373 #ifndef PRODUCT
2374   for( uint i = 0; i < _cnt; i++ )
2375     if( _nodes[i] ) {
2376       tty->print("%5d--> ",i);
2377       _nodes[i]->dump();
2378     }
2379 #endif
2380 }
2381 
2382 void Node_List::dump_simple() const {
2383 #ifndef PRODUCT
2384   for( uint i = 0; i < _cnt; i++ )
2385     if( _nodes[i] ) {
2386       tty->print(" %d", _nodes[i]->_idx);
2387     } else {
2388       tty->print(" NULL");
2389     }
2390 #endif
2391 }
2392 
2393 //=============================================================================
2394 //------------------------------remove-----------------------------------------
2395 void Unique_Node_List::remove( Node *n ) {
2396   if( _in_worklist[n->_idx] ) {
2397     for( uint i = 0; i < size(); i++ )
2398       if( _nodes[i] == n ) {
2399         map(i,Node_List::pop());
2400         _in_worklist >>= n->_idx;
2401         return;
2402       }
2403     ShouldNotReachHere();
2404   }
2405 }
2406 
2407 //-----------------------remove_useless_nodes----------------------------------
2408 // Remove useless nodes from worklist
2409 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2410 
2411   for( uint i = 0; i < size(); ++i ) {
2412     Node *n = at(i);
2413     assert( n != NULL, "Did not expect null entries in worklist");
2414     if( ! useful.test(n->_idx) ) {
2415       _in_worklist >>= n->_idx;
2416       map(i,Node_List::pop());
2417       // Node *replacement = Node_List::pop();
2418       // if( i != size() ) { // Check if removing last entry
2419       //   _nodes[i] = replacement;
2420       // }
2421       --i;  // Visit popped node
2422       // If it was last entry, loop terminates since size() was also reduced
2423     }
2424   }
2425 }
2426 
2427 //=============================================================================
2428 void Node_Stack::grow() {
2429   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2430   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2431   size_t max = old_max << 1;             // max * 2
2432   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2433   _inode_max = _inodes + max;
2434   _inode_top = _inodes + old_top;        // restore _top
2435 }
2436 
2437 // Node_Stack is used to map nodes.
2438 Node* Node_Stack::find(uint idx) const {
2439   uint sz = size();
2440   for (uint i=0; i < sz; i++) {
2441     if (idx == index_at(i) )
2442       return node_at(i);
2443   }
2444   return NULL;
2445 }
2446 
2447 //=============================================================================
2448 uint TypeNode::size_of() const { return sizeof(*this); }
2449 #ifndef PRODUCT
2450 void TypeNode::dump_spec(outputStream *st) const {
2451   if( !Verbose && !WizardMode ) {
2452     // standard dump does this in Verbose and WizardMode
2453     st->print(" #"); _type->dump_on(st);
2454   }
2455 }
2456 
2457 void TypeNode::dump_compact_spec(outputStream *st) const {
2458   st->print("#");
2459   _type->dump_on(st);
2460 }
2461 #endif
2462 uint TypeNode::hash() const {
2463   return Node::hash() + _type->hash();
2464 }
2465 bool TypeNode::cmp( const Node &n ) const
2466 { return !Type::cmp( _type, ((TypeNode&)n)._type ); }
2467 const Type *TypeNode::bottom_type() const { return _type; }
2468 const Type* TypeNode::Value(PhaseGVN* phase) const { return _type; }
2469 
2470 //------------------------------ideal_reg--------------------------------------
2471 uint TypeNode::ideal_reg() const {
2472   return _type->ideal_reg();
2473 }