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 "libadt/vectset.hpp"
  27 #include "memory/allocation.inline.hpp"

  28 #include "opto/cfgnode.hpp"
  29 #include "opto/connode.hpp"
  30 #include "opto/loopnode.hpp"
  31 #include "opto/machnode.hpp"
  32 #include "opto/matcher.hpp"
  33 #include "opto/node.hpp"
  34 #include "opto/opcodes.hpp"
  35 #include "opto/regmask.hpp"
  36 #include "opto/type.hpp"
  37 #include "utilities/copy.hpp"
  38 
  39 class RegMask;
  40 // #include "phase.hpp"
  41 class PhaseTransform;
  42 class PhaseGVN;
  43 
  44 // Arena we are currently building Nodes in
  45 const uint Node::NotAMachineReg = 0xffff0000;
  46 
  47 #ifndef PRODUCT
  48 extern int nodes_created;
  49 #endif
  50 #ifdef __clang__
  51 #pragma clang diagnostic push
  52 #pragma GCC diagnostic ignored "-Wuninitialized"
  53 #endif
  54 
  55 #ifdef ASSERT
  56 
  57 //-------------------------- construct_node------------------------------------
  58 // Set a breakpoint here to identify where a particular node index is built.
  59 void Node::verify_construction() {
  60   _debug_orig = NULL;
  61   int old_debug_idx = Compile::debug_idx();
  62   int new_debug_idx = old_debug_idx+1;
  63   if (new_debug_idx > 0) {
  64     // Arrange that the lowest five decimal digits of _debug_idx
  65     // will repeat those of _idx. In case this is somehow pathological,
  66     // we continue to assign negative numbers (!) consecutively.
  67     const int mod = 100000;
  68     int bump = (int)(_idx - new_debug_idx) % mod;
  69     if (bump < 0)  bump += mod;
  70     assert(bump >= 0 && bump < mod, "");
  71     new_debug_idx += bump;
  72   }
  73   Compile::set_debug_idx(new_debug_idx);
  74   set_debug_idx( new_debug_idx );
  75   assert(Compile::current()->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  76   assert(Compile::current()->live_nodes() < Compile::current()->max_node_limit(), "Live Node limit exceeded limit");
  77   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (int)_idx == BreakAtNode)) {
  78     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d", _idx, _debug_idx);
  79     BREAKPOINT;
  80   }
  81 #if OPTO_DU_ITERATOR_ASSERT
  82   _last_del = NULL;
  83   _del_tick = 0;
  84 #endif
  85   _hash_lock = 0;
  86 }
  87 
  88 
  89 // #ifdef ASSERT ...
  90 
  91 #if OPTO_DU_ITERATOR_ASSERT
  92 void DUIterator_Common::sample(const Node* node) {
  93   _vdui     = VerifyDUIterators;
  94   _node     = node;
  95   _outcnt   = node->_outcnt;
  96   _del_tick = node->_del_tick;
  97   _last     = NULL;
  98 }
  99 
 100 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
 101   assert(_node     == node, "consistent iterator source");
 102   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
 103 }
 104 
 105 void DUIterator_Common::verify_resync() {
 106   // Ensure that the loop body has just deleted the last guy produced.
 107   const Node* node = _node;
 108   // Ensure that at least one copy of the last-seen edge was deleted.
 109   // Note:  It is OK to delete multiple copies of the last-seen edge.
 110   // Unfortunately, we have no way to verify that all the deletions delete
 111   // that same edge.  On this point we must use the Honor System.
 112   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 113   assert(node->_last_del == _last, "must have deleted the edge just produced");
 114   // We liked this deletion, so accept the resulting outcnt and tick.
 115   _outcnt   = node->_outcnt;
 116   _del_tick = node->_del_tick;
 117 }
 118 
 119 void DUIterator_Common::reset(const DUIterator_Common& that) {
 120   if (this == &that)  return;  // ignore assignment to self
 121   if (!_vdui) {
 122     // We need to initialize everything, overwriting garbage values.
 123     _last = that._last;
 124     _vdui = that._vdui;
 125   }
 126   // Note:  It is legal (though odd) for an iterator over some node x
 127   // to be reassigned to iterate over another node y.  Some doubly-nested
 128   // progress loops depend on being able to do this.
 129   const Node* node = that._node;
 130   // Re-initialize everything, except _last.
 131   _node     = node;
 132   _outcnt   = node->_outcnt;
 133   _del_tick = node->_del_tick;
 134 }
 135 
 136 void DUIterator::sample(const Node* node) {
 137   DUIterator_Common::sample(node);      // Initialize the assertion data.
 138   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 139 }
 140 
 141 void DUIterator::verify(const Node* node, bool at_end_ok) {
 142   DUIterator_Common::verify(node, at_end_ok);
 143   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 144 }
 145 
 146 void DUIterator::verify_increment() {
 147   if (_refresh_tick & 1) {
 148     // We have refreshed the index during this loop.
 149     // Fix up _idx to meet asserts.
 150     if (_idx > _outcnt)  _idx = _outcnt;
 151   }
 152   verify(_node, true);
 153 }
 154 
 155 void DUIterator::verify_resync() {
 156   // Note:  We do not assert on _outcnt, because insertions are OK here.
 157   DUIterator_Common::verify_resync();
 158   // Make sure we are still in sync, possibly with no more out-edges:
 159   verify(_node, true);
 160 }
 161 
 162 void DUIterator::reset(const DUIterator& that) {
 163   if (this == &that)  return;  // self assignment is always a no-op
 164   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 165   assert(that._idx          == 0, "assign only the result of Node::outs()");
 166   assert(_idx               == that._idx, "already assigned _idx");
 167   if (!_vdui) {
 168     // We need to initialize everything, overwriting garbage values.
 169     sample(that._node);
 170   } else {
 171     DUIterator_Common::reset(that);
 172     if (_refresh_tick & 1) {
 173       _refresh_tick++;                  // Clear the "was refreshed" flag.
 174     }
 175     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 176   }
 177 }
 178 
 179 void DUIterator::refresh() {
 180   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 181   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 182 }
 183 
 184 void DUIterator::verify_finish() {
 185   // If the loop has killed the node, do not require it to re-run.
 186   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 187   // If this assert triggers, it means that a loop used refresh_out_pos
 188   // to re-synch an iteration index, but the loop did not correctly
 189   // re-run itself, using a "while (progress)" construct.
 190   // This iterator enforces the rule that you must keep trying the loop
 191   // until it "runs clean" without any need for refreshing.
 192   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 193 }
 194 
 195 
 196 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 197   DUIterator_Common::verify(node, at_end_ok);
 198   Node** out    = node->_out;
 199   uint   cnt    = node->_outcnt;
 200   assert(cnt == _outcnt, "no insertions allowed");
 201   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 202   // This last check is carefully designed to work for NO_OUT_ARRAY.
 203 }
 204 
 205 void DUIterator_Fast::verify_limit() {
 206   const Node* node = _node;
 207   verify(node, true);
 208   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 209 }
 210 
 211 void DUIterator_Fast::verify_resync() {
 212   const Node* node = _node;
 213   if (_outp == node->_out + _outcnt) {
 214     // Note that the limit imax, not the pointer i, gets updated with the
 215     // exact count of deletions.  (For the pointer it's always "--i".)
 216     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 217     // This is a limit pointer, with a name like "imax".
 218     // Fudge the _last field so that the common assert will be happy.
 219     _last = (Node*) node->_last_del;
 220     DUIterator_Common::verify_resync();
 221   } else {
 222     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 223     // A normal internal pointer.
 224     DUIterator_Common::verify_resync();
 225     // Make sure we are still in sync, possibly with no more out-edges:
 226     verify(node, true);
 227   }
 228 }
 229 
 230 void DUIterator_Fast::verify_relimit(uint n) {
 231   const Node* node = _node;
 232   assert((int)n > 0, "use imax -= n only with a positive count");
 233   // This must be a limit pointer, with a name like "imax".
 234   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 235   // The reported number of deletions must match what the node saw.
 236   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 237   // Fudge the _last field so that the common assert will be happy.
 238   _last = (Node*) node->_last_del;
 239   DUIterator_Common::verify_resync();
 240 }
 241 
 242 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 243   assert(_outp              == that._outp, "already assigned _outp");
 244   DUIterator_Common::reset(that);
 245 }
 246 
 247 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 248   // at_end_ok means the _outp is allowed to underflow by 1
 249   _outp += at_end_ok;
 250   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 251   _outp -= at_end_ok;
 252   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 253 }
 254 
 255 void DUIterator_Last::verify_limit() {
 256   // Do not require the limit address to be resynched.
 257   //verify(node, true);
 258   assert(_outp == _node->_out, "limit still correct");
 259 }
 260 
 261 void DUIterator_Last::verify_step(uint num_edges) {
 262   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 263   _outcnt   -= num_edges;
 264   _del_tick += num_edges;
 265   // Make sure we are still in sync, possibly with no more out-edges:
 266   const Node* node = _node;
 267   verify(node, true);
 268   assert(node->_last_del == _last, "must have deleted the edge just produced");
 269 }
 270 
 271 #endif //OPTO_DU_ITERATOR_ASSERT
 272 
 273 
 274 #endif //ASSERT
 275 
 276 
 277 // This constant used to initialize _out may be any non-null value.
 278 // The value NULL is reserved for the top node only.
 279 #define NO_OUT_ARRAY ((Node**)-1)
 280 
 281 // Out-of-line code from node constructors.
 282 // Executed only when extra debug info. is being passed around.
 283 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 284   C->set_node_notes_at(idx, nn);
 285 }
 286 
 287 // Shared initialization code.
 288 inline int Node::Init(int req) {
 289   Compile* C = Compile::current();
 290   int idx = C->next_unique();
 291 
 292   // Allocate memory for the necessary number of edges.
 293   if (req > 0) {
 294     // Allocate space for _in array to have double alignment.
 295     _in = (Node **) ((char *) (C->node_arena()->Amalloc_D(req * sizeof(void*))));
 296 #ifdef ASSERT
 297     _in[req-1] = this; // magic cookie for assertion check
 298 #endif
 299   }
 300   // If there are default notes floating around, capture them:
 301   Node_Notes* nn = C->default_node_notes();
 302   if (nn != NULL)  init_node_notes(C, idx, nn);
 303 
 304   // Note:  At this point, C is dead,
 305   // and we begin to initialize the new Node.
 306 
 307   _cnt = _max = req;
 308   _outcnt = _outmax = 0;
 309   _class_id = Class_Node;
 310   _flags = 0;
 311   _out = NO_OUT_ARRAY;
 312   return idx;
 313 }
 314 
 315 //------------------------------Node-------------------------------------------
 316 // Create a Node, with a given number of required edges.
 317 Node::Node(uint req)
 318   : _idx(Init(req))
 319 #ifdef ASSERT
 320   , _parse_idx(_idx)
 321 #endif
 322 {
 323   assert( req < Compile::current()->max_node_limit() - NodeLimitFudgeFactor, "Input limit exceeded" );
 324   debug_only( verify_construction() );
 325   NOT_PRODUCT(nodes_created++);
 326   if (req == 0) {
 327     assert( _in == (Node**)this, "Must not pass arg count to 'new'" );
 328     _in = NULL;
 329   } else {
 330     assert( _in[req-1] == this, "Must pass arg count to 'new'" );
 331     Node** to = _in;
 332     for(uint i = 0; i < req; i++) {
 333       to[i] = NULL;
 334     }
 335   }
 336 }
 337 
 338 //------------------------------Node-------------------------------------------
 339 Node::Node(Node *n0)
 340   : _idx(Init(1))
 341 #ifdef ASSERT
 342   , _parse_idx(_idx)
 343 #endif
 344 {
 345   debug_only( verify_construction() );
 346   NOT_PRODUCT(nodes_created++);
 347   // Assert we allocated space for input array already
 348   assert( _in[0] == this, "Must pass arg count to 'new'" );
 349   assert( is_not_dead(n0), "can not use dead node");
 350   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 351 }
 352 
 353 //------------------------------Node-------------------------------------------
 354 Node::Node(Node *n0, Node *n1)
 355   : _idx(Init(2))
 356 #ifdef ASSERT
 357   , _parse_idx(_idx)
 358 #endif
 359 {
 360   debug_only( verify_construction() );
 361   NOT_PRODUCT(nodes_created++);
 362   // Assert we allocated space for input array already
 363   assert( _in[1] == this, "Must pass arg count to 'new'" );
 364   assert( is_not_dead(n0), "can not use dead node");
 365   assert( is_not_dead(n1), "can not use dead node");
 366   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 367   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 368 }
 369 
 370 //------------------------------Node-------------------------------------------
 371 Node::Node(Node *n0, Node *n1, Node *n2)
 372   : _idx(Init(3))
 373 #ifdef ASSERT
 374   , _parse_idx(_idx)
 375 #endif
 376 {
 377   debug_only( verify_construction() );
 378   NOT_PRODUCT(nodes_created++);
 379   // Assert we allocated space for input array already
 380   assert( _in[2] == this, "Must pass arg count to 'new'" );
 381   assert( is_not_dead(n0), "can not use dead node");
 382   assert( is_not_dead(n1), "can not use dead node");
 383   assert( is_not_dead(n2), "can not use dead node");
 384   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 385   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 386   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 387 }
 388 
 389 //------------------------------Node-------------------------------------------
 390 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 391   : _idx(Init(4))
 392 #ifdef ASSERT
 393   , _parse_idx(_idx)
 394 #endif
 395 {
 396   debug_only( verify_construction() );
 397   NOT_PRODUCT(nodes_created++);
 398   // Assert we allocated space for input array already
 399   assert( _in[3] == this, "Must pass arg count to 'new'" );
 400   assert( is_not_dead(n0), "can not use dead node");
 401   assert( is_not_dead(n1), "can not use dead node");
 402   assert( is_not_dead(n2), "can not use dead node");
 403   assert( is_not_dead(n3), "can not use dead node");
 404   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 405   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 406   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 407   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 408 }
 409 
 410 //------------------------------Node-------------------------------------------
 411 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 412   : _idx(Init(5))
 413 #ifdef ASSERT
 414   , _parse_idx(_idx)
 415 #endif
 416 {
 417   debug_only( verify_construction() );
 418   NOT_PRODUCT(nodes_created++);
 419   // Assert we allocated space for input array already
 420   assert( _in[4] == this, "Must pass arg count to 'new'" );
 421   assert( is_not_dead(n0), "can not use dead node");
 422   assert( is_not_dead(n1), "can not use dead node");
 423   assert( is_not_dead(n2), "can not use dead node");
 424   assert( is_not_dead(n3), "can not use dead node");
 425   assert( is_not_dead(n4), "can not use dead node");
 426   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 427   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 428   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 429   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 430   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 431 }
 432 
 433 //------------------------------Node-------------------------------------------
 434 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 435                      Node *n4, Node *n5)
 436   : _idx(Init(6))
 437 #ifdef ASSERT
 438   , _parse_idx(_idx)
 439 #endif
 440 {
 441   debug_only( verify_construction() );
 442   NOT_PRODUCT(nodes_created++);
 443   // Assert we allocated space for input array already
 444   assert( _in[5] == this, "Must pass arg count to 'new'" );
 445   assert( is_not_dead(n0), "can not use dead node");
 446   assert( is_not_dead(n1), "can not use dead node");
 447   assert( is_not_dead(n2), "can not use dead node");
 448   assert( is_not_dead(n3), "can not use dead node");
 449   assert( is_not_dead(n4), "can not use dead node");
 450   assert( is_not_dead(n5), "can not use dead node");
 451   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 452   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 453   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 454   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 455   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 456   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 457 }
 458 
 459 //------------------------------Node-------------------------------------------
 460 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 461                      Node *n4, Node *n5, Node *n6)
 462   : _idx(Init(7))
 463 #ifdef ASSERT
 464   , _parse_idx(_idx)
 465 #endif
 466 {
 467   debug_only( verify_construction() );
 468   NOT_PRODUCT(nodes_created++);
 469   // Assert we allocated space for input array already
 470   assert( _in[6] == this, "Must pass arg count to 'new'" );
 471   assert( is_not_dead(n0), "can not use dead node");
 472   assert( is_not_dead(n1), "can not use dead node");
 473   assert( is_not_dead(n2), "can not use dead node");
 474   assert( is_not_dead(n3), "can not use dead node");
 475   assert( is_not_dead(n4), "can not use dead node");
 476   assert( is_not_dead(n5), "can not use dead node");
 477   assert( is_not_dead(n6), "can not use dead node");
 478   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 479   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 480   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 481   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 482   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 483   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 484   _in[6] = n6; if (n6 != NULL) n6->add_out((Node *)this);
 485 }
 486 
 487 #ifdef __clang__
 488 #pragma clang diagnostic pop
 489 #endif
 490 
 491 
 492 //------------------------------clone------------------------------------------
 493 // Clone a Node.
 494 Node *Node::clone() const {
 495   Compile* C = Compile::current();
 496   uint s = size_of();           // Size of inherited Node
 497   Node *n = (Node*)C->node_arena()->Amalloc_D(size_of() + _max*sizeof(Node*));
 498   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 499   // Set the new input pointer array
 500   n->_in = (Node**)(((char*)n)+s);
 501   // Cannot share the old output pointer array, so kill it
 502   n->_out = NO_OUT_ARRAY;
 503   // And reset the counters to 0
 504   n->_outcnt = 0;
 505   n->_outmax = 0;
 506   // Unlock this guy, since he is not in any hash table.
 507   debug_only(n->_hash_lock = 0);
 508   // Walk the old node's input list to duplicate its edges
 509   uint i;
 510   for( i = 0; i < len(); i++ ) {
 511     Node *x = in(i);
 512     n->_in[i] = x;
 513     if (x != NULL) x->add_out(n);
 514   }
 515   if (is_macro())
 516     C->add_macro_node(n);
 517   if (is_expensive())
 518     C->add_expensive_node(n);





 519 
 520   n->set_idx(C->next_unique()); // Get new unique index as well
 521   debug_only( n->verify_construction() );
 522   NOT_PRODUCT(nodes_created++);
 523   // Do not patch over the debug_idx of a clone, because it makes it
 524   // impossible to break on the clone's moment of creation.
 525   //debug_only( n->set_debug_idx( debug_idx() ) );
 526 
 527   C->copy_node_notes_to(n, (Node*) this);
 528 
 529   // MachNode clone
 530   uint nopnds;
 531   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 532     MachNode *mach  = n->as_Mach();
 533     MachNode *mthis = this->as_Mach();
 534     // Get address of _opnd_array.
 535     // It should be the same offset since it is the clone of this node.
 536     MachOper **from = mthis->_opnds;
 537     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 538                     pointer_delta((const void*)from,
 539                                   (const void*)(&mthis->_opnds), 1));
 540     mach->_opnds = to;
 541     for ( uint i = 0; i < nopnds; ++i ) {
 542       to[i] = from[i]->clone();
 543     }
 544   }
 545   // cloning CallNode may need to clone JVMState
 546   if (n->is_Call()) {
 547     n->as_Call()->clone_jvms(C);
 548   }
 549   if (n->is_SafePoint()) {
 550     n->as_SafePoint()->clone_replaced_nodes();
 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 
 571 //------------------------------~Node------------------------------------------
 572 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 573 extern int reclaim_idx ;
 574 extern int reclaim_in  ;
 575 extern int reclaim_node;
 576 void Node::destruct() {
 577   // Eagerly reclaim unique Node numberings
 578   Compile* compile = Compile::current();
 579   if ((uint)_idx+1 == compile->unique()) {
 580     compile->set_unique(compile->unique()-1);
 581 #ifdef ASSERT
 582     reclaim_idx++;
 583 #endif
 584   }
 585   // Clear debug info:
 586   Node_Notes* nn = compile->node_notes_at(_idx);
 587   if (nn != NULL)  nn->clear();
 588   // Walk the input array, freeing the corresponding output edges
 589   _cnt = _max;  // forget req/prec distinction
 590   uint i;
 591   for( i = 0; i < _max; i++ ) {
 592     set_req(i, NULL);
 593     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 594   }
 595   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 596   // See if the input array was allocated just prior to the object
 597   int edge_size = _max*sizeof(void*);
 598   int out_edge_size = _outmax*sizeof(void*);
 599   char *edge_end = ((char*)_in) + edge_size;
 600   char *out_array = (char*)(_out == NO_OUT_ARRAY? NULL: _out);
 601   char *out_edge_end = out_array + out_edge_size;
 602   int node_size = size_of();
 603 
 604   // Free the output edge array
 605   if (out_edge_size > 0) {
 606 #ifdef ASSERT
 607     if( out_edge_end == compile->node_arena()->hwm() )
 608       reclaim_in  += out_edge_size;  // count reclaimed out edges with in edges
 609 #endif
 610     compile->node_arena()->Afree(out_array, out_edge_size);
 611   }
 612 
 613   // Free the input edge array and the node itself
 614   if( edge_end == (char*)this ) {
 615 #ifdef ASSERT
 616     if( edge_end+node_size == compile->node_arena()->hwm() ) {
 617       reclaim_in  += edge_size;
 618       reclaim_node+= node_size;
 619     }
 620 #else
 621     // It was; free the input array and object all in one hit
 622     compile->node_arena()->Afree(_in,edge_size+node_size);
 623 #endif
 624   } else {
 625 
 626     // Free just the input array
 627 #ifdef ASSERT
 628     if( edge_end == compile->node_arena()->hwm() )
 629       reclaim_in  += edge_size;
 630 #endif
 631     compile->node_arena()->Afree(_in,edge_size);
 632 
 633     // Free just the object
 634 #ifdef ASSERT
 635     if( ((char*)this) + node_size == compile->node_arena()->hwm() )
 636       reclaim_node+= node_size;
 637 #else
 638     compile->node_arena()->Afree(this,node_size);
 639 #endif
 640   }
 641   if (is_macro()) {
 642     compile->remove_macro_node(this);
 643   }
 644   if (is_expensive()) {
 645     compile->remove_expensive_node(this);
 646   }





 647   if (is_SafePoint()) {
 648     as_SafePoint()->delete_replaced_nodes();
 649   }
 650 #ifdef ASSERT
 651   // We will not actually delete the storage, but we'll make the node unusable.
 652   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 653   _in = _out = (Node**) badAddress;
 654   _max = _cnt = _outmax = _outcnt = 0;
 655   compile->remove_modified_node(this);
 656 #endif
 657 }
 658 
 659 //------------------------------grow-------------------------------------------
 660 // Grow the input array, making space for more edges
 661 void Node::grow( uint len ) {
 662   Arena* arena = Compile::current()->node_arena();
 663   uint new_max = _max;
 664   if( new_max == 0 ) {
 665     _max = 4;
 666     _in = (Node**)arena->Amalloc(4*sizeof(Node*));
 667     Node** to = _in;
 668     to[0] = NULL;
 669     to[1] = NULL;
 670     to[2] = NULL;
 671     to[3] = NULL;
 672     return;
 673   }
 674   while( new_max <= len ) new_max <<= 1; // Find next power-of-2
 675   // Trimming to limit allows a uint8 to handle up to 255 edges.
 676   // Previously I was using only powers-of-2 which peaked at 128 edges.
 677   //if( new_max >= limit ) new_max = limit-1;
 678   _in = (Node**)arena->Arealloc(_in, _max*sizeof(Node*), new_max*sizeof(Node*));
 679   Copy::zero_to_bytes(&_in[_max], (new_max-_max)*sizeof(Node*)); // NULL all new space
 680   _max = new_max;               // Record new max length
 681   // This assertion makes sure that Node::_max is wide enough to
 682   // represent the numerical value of new_max.
 683   assert(_max == new_max && _max > len, "int width of _max is too small");
 684 }
 685 
 686 //-----------------------------out_grow----------------------------------------
 687 // Grow the input array, making space for more edges
 688 void Node::out_grow( uint len ) {
 689   assert(!is_top(), "cannot grow a top node's out array");
 690   Arena* arena = Compile::current()->node_arena();
 691   uint new_max = _outmax;
 692   if( new_max == 0 ) {
 693     _outmax = 4;
 694     _out = (Node **)arena->Amalloc(4*sizeof(Node*));
 695     return;
 696   }
 697   while( new_max <= len ) new_max <<= 1; // Find next power-of-2
 698   // Trimming to limit allows a uint8 to handle up to 255 edges.
 699   // Previously I was using only powers-of-2 which peaked at 128 edges.
 700   //if( new_max >= limit ) new_max = limit-1;
 701   assert(_out != NULL && _out != NO_OUT_ARRAY, "out must have sensible value");
 702   _out = (Node**)arena->Arealloc(_out,_outmax*sizeof(Node*),new_max*sizeof(Node*));
 703   //Copy::zero_to_bytes(&_out[_outmax], (new_max-_outmax)*sizeof(Node*)); // NULL all new space
 704   _outmax = new_max;               // Record new max length
 705   // This assertion makes sure that Node::_max is wide enough to
 706   // represent the numerical value of new_max.
 707   assert(_outmax == new_max && _outmax > len, "int width of _outmax is too small");
 708 }
 709 
 710 #ifdef ASSERT
 711 //------------------------------is_dead----------------------------------------
 712 bool Node::is_dead() const {
 713   // Mach and pinch point nodes may look like dead.
 714   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 715     return false;
 716   for( uint i = 0; i < _max; i++ )
 717     if( _in[i] != NULL )
 718       return false;
 719   dump();
 720   return true;
 721 }
 722 #endif
 723 
 724 
 725 //------------------------------is_unreachable---------------------------------
 726 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 727   assert(!is_Mach(), "doesn't work with MachNodes");
 728   return outcnt() == 0 || igvn.type(this) == Type::TOP || in(0)->is_top();
 729 }
 730 
 731 //------------------------------add_req----------------------------------------
 732 // Add a new required input at the end
 733 void Node::add_req( Node *n ) {
 734   assert( is_not_dead(n), "can not use dead node");
 735 
 736   // Look to see if I can move precedence down one without reallocating
 737   if( (_cnt >= _max) || (in(_max-1) != NULL) )
 738     grow( _max+1 );
 739 
 740   // Find a precedence edge to move
 741   if( in(_cnt) != NULL ) {       // Next precedence edge is busy?
 742     uint i;
 743     for( i=_cnt; i<_max; i++ )
 744       if( in(i) == NULL )       // Find the NULL at end of prec edge list
 745         break;                  // There must be one, since we grew the array
 746     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 747   }
 748   _in[_cnt++] = n;            // Stuff over old prec edge
 749   if (n != NULL) n->add_out((Node *)this);
 750 }
 751 
 752 //---------------------------add_req_batch-------------------------------------
 753 // Add a new required input at the end
 754 void Node::add_req_batch( Node *n, uint m ) {
 755   assert( is_not_dead(n), "can not use dead node");
 756   // check various edge cases
 757   if ((int)m <= 1) {
 758     assert((int)m >= 0, "oob");
 759     if (m != 0)  add_req(n);
 760     return;
 761   }
 762 
 763   // Look to see if I can move precedence down one without reallocating
 764   if( (_cnt+m) > _max || _in[_max-m] )
 765     grow( _max+m );
 766 
 767   // Find a precedence edge to move
 768   if( _in[_cnt] != NULL ) {     // Next precedence edge is busy?
 769     uint i;
 770     for( i=_cnt; i<_max; i++ )
 771       if( _in[i] == NULL )      // Find the NULL at end of prec edge list
 772         break;                  // There must be one, since we grew the array
 773     // Slide all the precs over by m positions (assume #prec << m).
 774     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 775   }
 776 
 777   // Stuff over the old prec edges
 778   for(uint i=0; i<m; i++ ) {
 779     _in[_cnt++] = n;
 780   }
 781 
 782   // Insert multiple out edges on the node.
 783   if (n != NULL && !n->is_top()) {
 784     for(uint i=0; i<m; i++ ) {
 785       n->add_out((Node *)this);
 786     }
 787   }
 788 }
 789 
 790 //------------------------------del_req----------------------------------------
 791 // Delete the required edge and compact the edge array
 792 void Node::del_req( 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   _in[idx] = in(--_cnt); // Compact the array
 800   // Avoid spec violation: Gap in prec edges.
 801   close_prec_gap_at(_cnt);
 802   Compile::current()->record_modified_node(this);
 803 }
 804 
 805 //------------------------------del_req_ordered--------------------------------
 806 // Delete the required edge and compact the edge array with preserved order
 807 void Node::del_req_ordered( uint idx ) {
 808   assert( idx < _cnt, "oob");
 809   assert( !VerifyHashTableKeys || _hash_lock == 0,
 810           "remove node from hash table before modifying it");
 811   // First remove corresponding def-use edge
 812   Node *n = in(idx);
 813   if (n != NULL) n->del_out((Node *)this);
 814   if (idx < --_cnt) {    // Not last edge ?
 815     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
 816   }
 817   // Avoid spec violation: Gap in prec edges.
 818   close_prec_gap_at(_cnt);
 819   Compile::current()->record_modified_node(this);
 820 }
 821 
 822 //------------------------------ins_req----------------------------------------
 823 // Insert a new required input at the end
 824 void Node::ins_req( uint idx, Node *n ) {
 825   assert( is_not_dead(n), "can not use dead node");
 826   add_req(NULL);                // Make space
 827   assert( idx < _max, "Must have allocated enough space");
 828   // Slide over
 829   if(_cnt-idx-1 > 0) {
 830     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 831   }
 832   _in[idx] = n;                            // Stuff over old required edge
 833   if (n != NULL) n->add_out((Node *)this); // Add reciprocal def-use edge
 834 }
 835 
 836 //-----------------------------find_edge---------------------------------------
 837 int Node::find_edge(Node* n) {
 838   for (uint i = 0; i < len(); i++) {
 839     if (_in[i] == n)  return i;
 840   }
 841   return -1;
 842 }
 843 
 844 //----------------------------replace_edge-------------------------------------
 845 int Node::replace_edge(Node* old, Node* neww) {
 846   if (old == neww)  return 0;  // nothing to do
 847   uint nrep = 0;
 848   for (uint i = 0; i < len(); i++) {
 849     if (in(i) == old) {
 850       if (i < req()) {
 851         set_req(i, neww);
 852       } else {
 853         assert(find_prec_edge(neww) == -1, "spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx);
 854         set_prec(i, neww);
 855       }
 856       nrep++;
 857     }
 858   }
 859   return nrep;
 860 }
 861 
 862 /**
 863  * Replace input edges in the range pointing to 'old' node.
 864  */
 865 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end) {
 866   if (old == neww)  return 0;  // nothing to do
 867   uint nrep = 0;
 868   for (int i = start; i < end; i++) {
 869     if (in(i) == old) {
 870       set_req(i, neww);
 871       nrep++;
 872     }
 873   }
 874   return nrep;
 875 }
 876 
 877 //-------------------------disconnect_inputs-----------------------------------
 878 // NULL out all inputs to eliminate incoming Def-Use edges.
 879 // Return the number of edges between 'n' and 'this'
 880 int Node::disconnect_inputs(Node *n, Compile* C) {
 881   int edges_to_n = 0;
 882 
 883   uint cnt = req();
 884   for( uint i = 0; i < cnt; ++i ) {
 885     if( in(i) == 0 ) continue;
 886     if( in(i) == n ) ++edges_to_n;
 887     set_req(i, NULL);
 888   }
 889   // Remove precedence edges if any exist
 890   // Note: Safepoints may have precedence edges, even during parsing
 891   if( (req() != len()) && (in(req()) != NULL) ) {
 892     uint max = len();
 893     for( uint i = 0; i < max; ++i ) {
 894       if( in(i) == 0 ) continue;
 895       if( in(i) == n ) ++edges_to_n;
 896       set_prec(i, NULL);
 897     }
 898   }
 899 
 900   // Node::destruct requires all out edges be deleted first
 901   // debug_only(destruct();)   // no reuse benefit expected
 902   if (edges_to_n == 0) {
 903     C->record_dead_node(_idx);
 904   }
 905   return edges_to_n;
 906 }
 907 
 908 //-----------------------------uncast---------------------------------------
 909 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 910 // Strip away casting.  (It is depth-limited.)
 911 Node* Node::uncast() const {
 912   // Should be inline:
 913   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 914   if (is_ConstraintCast())
 915     return uncast_helper(this);
 916   else
 917     return (Node*) this;
 918 }
 919 
 920 // Find out of current node that matches opcode.
 921 Node* Node::find_out_with(int opcode) {
 922   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 923     Node* use = fast_out(i);
 924     if (use->Opcode() == opcode) {
 925       return use;
 926     }
 927   }
 928   return NULL;
 929 }
 930 
 931 // Return true if the current node has an out that matches opcode.
 932 bool Node::has_out_with(int opcode) {
 933   return (find_out_with(opcode) != NULL);
 934 }
 935 
 936 // Return true if the current node has an out that matches any of the opcodes.
 937 bool Node::has_out_with(int opcode1, int opcode2, int opcode3, int opcode4) {
 938   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 939       int opcode = fast_out(i)->Opcode();
 940       if (opcode == opcode1 || opcode == opcode2 || opcode == opcode3 || opcode == opcode4) {
 941         return true;
 942       }
 943   }
 944   return false;
 945 }
 946 
 947 
 948 //---------------------------uncast_helper-------------------------------------
 949 Node* Node::uncast_helper(const Node* p) {
 950 #ifdef ASSERT
 951   uint depth_count = 0;
 952   const Node* orig_p = p;
 953 #endif
 954 
 955   while (true) {
 956 #ifdef ASSERT
 957     if (depth_count >= K) {
 958       orig_p->dump(4);
 959       if (p != orig_p)
 960         p->dump(1);
 961     }
 962     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
 963 #endif
 964     if (p == NULL || p->req() != 2) {
 965       break;
 966     } else if (p->is_ConstraintCast()) {
 967       p = p->in(1);
 968     } else {
 969       break;
 970     }
 971   }
 972   return (Node*) p;
 973 }
 974 
 975 //------------------------------add_prec---------------------------------------
 976 // Add a new precedence input.  Precedence inputs are unordered, with
 977 // duplicates removed and NULLs packed down at the end.
 978 void Node::add_prec( Node *n ) {
 979   assert( is_not_dead(n), "can not use dead node");
 980 
 981   // Check for NULL at end
 982   if( _cnt >= _max || in(_max-1) )
 983     grow( _max+1 );
 984 
 985   // Find a precedence edge to move
 986   uint i = _cnt;
 987   while( in(i) != NULL ) {
 988     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
 989     i++;
 990   }
 991   _in[i] = n;                                // Stuff prec edge over NULL
 992   if ( n != NULL) n->add_out((Node *)this);  // Add mirror edge
 993 
 994 #ifdef ASSERT
 995   while ((++i)<_max) { assert(_in[i] == NULL, "spec violation: Gap in prec edges (node %d)", _idx); }
 996 #endif
 997 }
 998 
 999 //------------------------------rm_prec----------------------------------------
1000 // Remove a precedence input.  Precedence inputs are unordered, with
1001 // duplicates removed and NULLs packed down at the end.
1002 void Node::rm_prec( uint j ) {
1003   assert(j < _max, "oob: i=%d, _max=%d", j, _max);
1004   assert(j >= _cnt, "not a precedence edge");
1005   if (_in[j] == NULL) return;   // Avoid spec violation: Gap in prec edges.
1006   _in[j]->del_out((Node *)this);
1007   close_prec_gap_at(j);
1008 }
1009 
1010 //------------------------------size_of----------------------------------------
1011 uint Node::size_of() const { return sizeof(*this); }
1012 
1013 //------------------------------ideal_reg--------------------------------------
1014 uint Node::ideal_reg() const { return 0; }
1015 
1016 //------------------------------jvms-------------------------------------------
1017 JVMState* Node::jvms() const { return NULL; }
1018 
1019 #ifdef ASSERT
1020 //------------------------------jvms-------------------------------------------
1021 bool Node::verify_jvms(const JVMState* using_jvms) const {
1022   for (JVMState* jvms = this->jvms(); jvms != NULL; jvms = jvms->caller()) {
1023     if (jvms == using_jvms)  return true;
1024   }
1025   return false;
1026 }
1027 
1028 //------------------------------init_NodeProperty------------------------------
1029 void Node::init_NodeProperty() {
1030   assert(_max_classes <= max_jushort, "too many NodeProperty classes");
1031   assert(_max_flags <= max_jushort, "too many NodeProperty flags");
1032 }
1033 #endif
1034 
1035 //------------------------------format-----------------------------------------
1036 // Print as assembly
1037 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1038 //------------------------------emit-------------------------------------------
1039 // Emit bytes starting at parameter 'ptr'.
1040 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
1041 //------------------------------size-------------------------------------------
1042 // Size of instruction in bytes
1043 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1044 
1045 //------------------------------CFG Construction-------------------------------
1046 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1047 // Goto and Return.
1048 const Node *Node::is_block_proj() const { return 0; }
1049 
1050 // Minimum guaranteed type
1051 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1052 
1053 
1054 //------------------------------raise_bottom_type------------------------------
1055 // Get the worst-case Type output for this Node.
1056 void Node::raise_bottom_type(const Type* new_type) {
1057   if (is_Type()) {
1058     TypeNode *n = this->as_Type();
1059     if (VerifyAliases) {
1060       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1061     }
1062     n->set_type(new_type);
1063   } else if (is_Load()) {
1064     LoadNode *n = this->as_Load();
1065     if (VerifyAliases) {
1066       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1067     }
1068     n->set_type(new_type);
1069   }
1070 }
1071 
1072 //------------------------------Identity---------------------------------------
1073 // Return a node that the given node is equivalent to.
1074 Node* Node::Identity(PhaseGVN* phase) {
1075   return this;                  // Default to no identities
1076 }
1077 
1078 //------------------------------Value------------------------------------------
1079 // Compute a new Type for a node using the Type of the inputs.
1080 const Type* Node::Value(PhaseGVN* phase) const {
1081   return bottom_type();         // Default to worst-case Type
1082 }
1083 
1084 //------------------------------Ideal------------------------------------------
1085 //
1086 // 'Idealize' the graph rooted at this Node.
1087 //
1088 // In order to be efficient and flexible there are some subtle invariants
1089 // these Ideal calls need to hold.  Running with '+VerifyIterativeGVN' checks
1090 // these invariants, although its too slow to have on by default.  If you are
1091 // hacking an Ideal call, be sure to test with +VerifyIterativeGVN!
1092 //
1093 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1094 // pointer.  If ANY change is made, it must return the root of the reshaped
1095 // graph - even if the root is the same Node.  Example: swapping the inputs
1096 // to an AddINode gives the same answer and same root, but you still have to
1097 // return the 'this' pointer instead of NULL.
1098 //
1099 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1100 // Identity call to return an old Node; basically if Identity can find
1101 // another Node have the Ideal call make no change and return NULL.
1102 // Example: AddINode::Ideal must check for add of zero; in this case it
1103 // returns NULL instead of doing any graph reshaping.
1104 //
1105 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1106 // sharing there may be other users of the old Nodes relying on their current
1107 // semantics.  Modifying them will break the other users.
1108 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1109 // "X+3" unchanged in case it is shared.
1110 //
1111 // If you modify the 'this' pointer's inputs, you should use
1112 // 'set_req'.  If you are making a new Node (either as the new root or
1113 // some new internal piece) you may use 'init_req' to set the initial
1114 // value.  You can make a new Node with either 'new' or 'clone'.  In
1115 // either case, def-use info is correctly maintained.
1116 //
1117 // Example: reshape "(X+3)+4" into "X+7":
1118 //    set_req(1, in(1)->in(1));
1119 //    set_req(2, phase->intcon(7));
1120 //    return this;
1121 // Example: reshape "X*4" into "X<<2"
1122 //    return new LShiftINode(in(1), phase->intcon(2));
1123 //
1124 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1125 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1126 //    Node *shift=phase->transform(new LShiftINode(in(1),phase->intcon(5)));
1127 //    return new AddINode(shift, in(1));
1128 //
1129 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1130 // These forms are faster than 'phase->transform(new ConNode())' and Do
1131 // The Right Thing with def-use info.
1132 //
1133 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1134 // graph uses the 'this' Node it must be the root.  If you want a Node with
1135 // the same Opcode as the 'this' pointer use 'clone'.
1136 //
1137 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1138   return NULL;                  // Default to being Ideal already
1139 }
1140 
1141 // Some nodes have specific Ideal subgraph transformations only if they are
1142 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1143 // for the transformations to happen.
1144 bool Node::has_special_unique_user() const {
1145   assert(outcnt() == 1, "match only for unique out");
1146   Node* n = unique_out();
1147   int op  = Opcode();
1148   if (this->is_Store()) {
1149     // Condition for back-to-back stores folding.
1150     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1151   } else if (this->is_Load()) {
1152     // Condition for removing an unused LoadNode from the MemBarAcquire precedence input
1153     return n->Opcode() == Op_MemBarAcquire;
1154   } else if (op == Op_AddL) {
1155     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1156     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1157   } else if (op == Op_SubI || op == Op_SubL) {
1158     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1159     return n->Opcode() == op && n->in(2) == this;
1160   } else if (is_If() && (n->is_IfFalse() || n->is_IfTrue())) {
1161     // See IfProjNode::Identity()
1162     return true;
1163   }
1164   return false;
1165 };
1166 
1167 //--------------------------find_exact_control---------------------------------
1168 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1169 Node* Node::find_exact_control(Node* ctrl) {
1170   if (ctrl == NULL && this->is_Region())
1171     ctrl = this->as_Region()->is_copy();
1172 
1173   if (ctrl != NULL && ctrl->is_CatchProj()) {
1174     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1175       ctrl = ctrl->in(0);
1176     if (ctrl != NULL && !ctrl->is_top())
1177       ctrl = ctrl->in(0);
1178   }
1179 
1180   if (ctrl != NULL && ctrl->is_Proj())
1181     ctrl = ctrl->in(0);
1182 
1183   return ctrl;
1184 }
1185 
1186 //--------------------------dominates------------------------------------------
1187 // Helper function for MemNode::all_controls_dominate().
1188 // Check if 'this' control node dominates or equal to 'sub' control node.
1189 // We already know that if any path back to Root or Start reaches 'this',
1190 // then all paths so, so this is a simple search for one example,
1191 // not an exhaustive search for a counterexample.
1192 bool Node::dominates(Node* sub, Node_List &nlist) {
1193   assert(this->is_CFG(), "expecting control");
1194   assert(sub != NULL && sub->is_CFG(), "expecting control");
1195 
1196   // detect dead cycle without regions
1197   int iterations_without_region_limit = DominatorSearchLimit;
1198 
1199   Node* orig_sub = sub;
1200   Node* dom      = this;
1201   bool  met_dom  = false;
1202   nlist.clear();
1203 
1204   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1205   // After seeing 'dom', continue up to Root or Start.
1206   // If we hit a region (backward split point), it may be a loop head.
1207   // Keep going through one of the region's inputs.  If we reach the
1208   // same region again, go through a different input.  Eventually we
1209   // will either exit through the loop head, or give up.
1210   // (If we get confused, break out and return a conservative 'false'.)
1211   while (sub != NULL) {
1212     if (sub->is_top())  break; // Conservative answer for dead code.
1213     if (sub == dom) {
1214       if (nlist.size() == 0) {
1215         // No Region nodes except loops were visited before and the EntryControl
1216         // path was taken for loops: it did not walk in a cycle.
1217         return true;
1218       } else if (met_dom) {
1219         break;          // already met before: walk in a cycle
1220       } else {
1221         // Region nodes were visited. Continue walk up to Start or Root
1222         // to make sure that it did not walk in a cycle.
1223         met_dom = true; // first time meet
1224         iterations_without_region_limit = DominatorSearchLimit; // Reset
1225      }
1226     }
1227     if (sub->is_Start() || sub->is_Root()) {
1228       // Success if we met 'dom' along a path to Start or Root.
1229       // We assume there are no alternative paths that avoid 'dom'.
1230       // (This assumption is up to the caller to ensure!)
1231       return met_dom;
1232     }
1233     Node* up = sub->in(0);
1234     // Normalize simple pass-through regions and projections:
1235     up = sub->find_exact_control(up);
1236     // If sub == up, we found a self-loop.  Try to push past it.
1237     if (sub == up && sub->is_Loop()) {
1238       // Take loop entry path on the way up to 'dom'.
1239       up = sub->in(1); // in(LoopNode::EntryControl);
1240     } else if (sub == up && sub->is_Region() && sub->req() != 3) {
1241       // Always take in(1) path on the way up to 'dom' for clone regions
1242       // (with only one input) or regions which merge > 2 paths
1243       // (usually used to merge fast/slow paths).
1244       up = sub->in(1);
1245     } else if (sub == up && sub->is_Region()) {
1246       // Try both paths for Regions with 2 input paths (it may be a loop head).
1247       // It could give conservative 'false' answer without information
1248       // which region's input is the entry path.
1249       iterations_without_region_limit = DominatorSearchLimit; // Reset
1250 
1251       bool region_was_visited_before = false;
1252       // Was this Region node visited before?
1253       // If so, we have reached it because we accidentally took a
1254       // loop-back edge from 'sub' back into the body of the loop,
1255       // and worked our way up again to the loop header 'sub'.
1256       // So, take the first unexplored path on the way up to 'dom'.
1257       for (int j = nlist.size() - 1; j >= 0; j--) {
1258         intptr_t ni = (intptr_t)nlist.at(j);
1259         Node* visited = (Node*)(ni & ~1);
1260         bool  visited_twice_already = ((ni & 1) != 0);
1261         if (visited == sub) {
1262           if (visited_twice_already) {
1263             // Visited 2 paths, but still stuck in loop body.  Give up.
1264             return false;
1265           }
1266           // The Region node was visited before only once.
1267           // (We will repush with the low bit set, below.)
1268           nlist.remove(j);
1269           // We will find a new edge and re-insert.
1270           region_was_visited_before = true;
1271           break;
1272         }
1273       }
1274 
1275       // Find an incoming edge which has not been seen yet; walk through it.
1276       assert(up == sub, "");
1277       uint skip = region_was_visited_before ? 1 : 0;
1278       for (uint i = 1; i < sub->req(); i++) {
1279         Node* in = sub->in(i);
1280         if (in != NULL && !in->is_top() && in != sub) {
1281           if (skip == 0) {
1282             up = in;
1283             break;
1284           }
1285           --skip;               // skip this nontrivial input
1286         }
1287       }
1288 
1289       // Set 0 bit to indicate that both paths were taken.
1290       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1291     }
1292 
1293     if (up == sub) {
1294       break;    // some kind of tight cycle
1295     }
1296     if (up == orig_sub && met_dom) {
1297       // returned back after visiting 'dom'
1298       break;    // some kind of cycle
1299     }
1300     if (--iterations_without_region_limit < 0) {
1301       break;    // dead cycle
1302     }
1303     sub = up;
1304   }
1305 
1306   // Did not meet Root or Start node in pred. chain.
1307   // Conservative answer for dead code.
1308   return false;
1309 }
1310 
1311 //------------------------------remove_dead_region-----------------------------
1312 // This control node is dead.  Follow the subgraph below it making everything
1313 // using it dead as well.  This will happen normally via the usual IterGVN
1314 // worklist but this call is more efficient.  Do not update use-def info
1315 // inside the dead region, just at the borders.
1316 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1317   // Con's are a popular node to re-hit in the hash table again.
1318   if( dead->is_Con() ) return;
1319 
1320   // Can't put ResourceMark here since igvn->_worklist uses the same arena
1321   // for verify pass with +VerifyOpto and we add/remove elements in it here.
1322   Node_List  nstack(Thread::current()->resource_area());
1323 
1324   Node *top = igvn->C->top();
1325   nstack.push(dead);
1326   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1327 
1328   while (nstack.size() > 0) {
1329     dead = nstack.pop();
1330     if (dead->outcnt() > 0) {
1331       // Keep dead node on stack until all uses are processed.
1332       nstack.push(dead);
1333       // For all Users of the Dead...    ;-)
1334       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1335         Node* use = dead->last_out(k);
1336         igvn->hash_delete(use);       // Yank from hash table prior to mod
1337         if (use->in(0) == dead) {     // Found another dead node
1338           assert (!use->is_Con(), "Control for Con node should be Root node.");
1339           use->set_req(0, top);       // Cut dead edge to prevent processing
1340           nstack.push(use);           // the dead node again.
1341         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1342                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1343                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1344           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1345           use->set_req(0, top);       // Cut self edge
1346           nstack.push(use);
1347         } else {                      // Else found a not-dead user
1348           // Dead if all inputs are top or null
1349           bool dead_use = !use->is_Root(); // Keep empty graph alive
1350           for (uint j = 1; j < use->req(); j++) {
1351             Node* in = use->in(j);
1352             if (in == dead) {         // Turn all dead inputs into TOP
1353               use->set_req(j, top);
1354             } else if (in != NULL && !in->is_top()) {
1355               dead_use = false;
1356             }
1357           }
1358           if (dead_use) {
1359             if (use->is_Region()) {
1360               use->set_req(0, top);   // Cut self edge
1361             }
1362             nstack.push(use);
1363           } else {
1364             igvn->_worklist.push(use);
1365           }
1366         }
1367         // Refresh the iterator, since any number of kills might have happened.
1368         k = dead->last_outs(kmin);
1369       }
1370     } else { // (dead->outcnt() == 0)
1371       // Done with outputs.
1372       igvn->hash_delete(dead);
1373       igvn->_worklist.remove(dead);
1374       igvn->C->remove_modified_node(dead);
1375       igvn->set_type(dead, Type::TOP);
1376       if (dead->is_macro()) {
1377         igvn->C->remove_macro_node(dead);
1378       }
1379       if (dead->is_expensive()) {
1380         igvn->C->remove_expensive_node(dead);




1381       }
1382       igvn->C->record_dead_node(dead->_idx);
1383       // Kill all inputs to the dead guy
1384       for (uint i=0; i < dead->req(); i++) {
1385         Node *n = dead->in(i);      // Get input to dead guy
1386         if (n != NULL && !n->is_top()) { // Input is valid?
1387           dead->set_req(i, top);    // Smash input away
1388           if (n->outcnt() == 0) {   // Input also goes dead?
1389             if (!n->is_Con())
1390               nstack.push(n);       // Clear it out as well
1391           } else if (n->outcnt() == 1 &&
1392                      n->has_special_unique_user()) {
1393             igvn->add_users_to_worklist( n );
1394           } else if (n->outcnt() <= 2 && n->is_Store()) {
1395             // Push store's uses on worklist to enable folding optimization for
1396             // store/store and store/load to the same address.
1397             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1398             // and remove_globally_dead_node().
1399             igvn->add_users_to_worklist( n );
1400           }
1401         }
1402       }
1403     } // (dead->outcnt() == 0)
1404   }   // while (nstack.size() > 0) for outputs
1405   return;
1406 }
1407 
1408 //------------------------------remove_dead_region-----------------------------
1409 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1410   Node *n = in(0);
1411   if( !n ) return false;
1412   // Lost control into this guy?  I.e., it became unreachable?
1413   // Aggressively kill all unreachable code.
1414   if (can_reshape && n->is_top()) {
1415     kill_dead_code(this, phase->is_IterGVN());
1416     return false; // Node is dead.
1417   }
1418 
1419   if( n->is_Region() && n->as_Region()->is_copy() ) {
1420     Node *m = n->nonnull_req();
1421     set_req(0, m);
1422     return true;
1423   }
1424   return false;
1425 }
1426 
1427 //------------------------------hash-------------------------------------------
1428 // Hash function over Nodes.
1429 uint Node::hash() const {
1430   uint sum = 0;
1431   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1432     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded NULLs
1433   return (sum>>2) + _cnt + Opcode();
1434 }
1435 
1436 //------------------------------cmp--------------------------------------------
1437 // Compare special parts of simple Nodes
1438 uint Node::cmp( const Node &n ) const {
1439   return 1;                     // Must be same
1440 }
1441 
1442 //------------------------------rematerialize-----------------------------------
1443 // Should we clone rather than spill this instruction?
1444 bool Node::rematerialize() const {
1445   if ( is_Mach() )
1446     return this->as_Mach()->rematerialize();
1447   else
1448     return (_flags & Flag_rematerialize) != 0;
1449 }
1450 
1451 //------------------------------needs_anti_dependence_check---------------------
1452 // Nodes which use memory without consuming it, hence need antidependences.
1453 bool Node::needs_anti_dependence_check() const {
1454   if( req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0 )
1455     return false;
1456   else
1457     return in(1)->bottom_type()->has_memory();
1458 }
1459 
1460 
1461 // Get an integer constant from a ConNode (or CastIINode).
1462 // Return a default value if there is no apparent constant here.
1463 const TypeInt* Node::find_int_type() const {
1464   if (this->is_Type()) {
1465     return this->as_Type()->type()->isa_int();
1466   } else if (this->is_Con()) {
1467     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1468     return this->bottom_type()->isa_int();
1469   }
1470   return NULL;
1471 }
1472 
1473 // Get a pointer constant from a ConstNode.
1474 // Returns the constant if it is a pointer ConstNode
1475 intptr_t Node::get_ptr() const {
1476   assert( Opcode() == Op_ConP, "" );
1477   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1478 }
1479 
1480 // Get a narrow oop constant from a ConNNode.
1481 intptr_t Node::get_narrowcon() const {
1482   assert( Opcode() == Op_ConN, "" );
1483   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1484 }
1485 
1486 // Get a long constant from a ConNode.
1487 // Return a default value if there is no apparent constant here.
1488 const TypeLong* Node::find_long_type() const {
1489   if (this->is_Type()) {
1490     return this->as_Type()->type()->isa_long();
1491   } else if (this->is_Con()) {
1492     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1493     return this->bottom_type()->isa_long();
1494   }
1495   return NULL;
1496 }
1497 
1498 
1499 /**
1500  * Return a ptr type for nodes which should have it.
1501  */
1502 const TypePtr* Node::get_ptr_type() const {
1503   const TypePtr* tp = this->bottom_type()->make_ptr();
1504 #ifdef ASSERT
1505   if (tp == NULL) {
1506     this->dump(1);
1507     assert((tp != NULL), "unexpected node type");
1508   }
1509 #endif
1510   return tp;
1511 }
1512 
1513 // Get a double constant from a ConstNode.
1514 // Returns the constant if it is a double ConstNode
1515 jdouble Node::getd() const {
1516   assert( Opcode() == Op_ConD, "" );
1517   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1518 }
1519 
1520 // Get a float constant from a ConstNode.
1521 // Returns the constant if it is a float ConstNode
1522 jfloat Node::getf() const {
1523   assert( Opcode() == Op_ConF, "" );
1524   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1525 }
1526 
1527 #ifndef PRODUCT
1528 
1529 //------------------------------find------------------------------------------
1530 // Find a neighbor of this Node with the given _idx
1531 // If idx is negative, find its absolute value, following both _in and _out.
1532 static void find_recur(Compile* C,  Node* &result, Node *n, int idx, bool only_ctrl,
1533                         VectorSet* old_space, VectorSet* new_space ) {
1534   int node_idx = (idx >= 0) ? idx : -idx;
1535   if (NotANode(n))  return;  // Gracefully handle NULL, -1, 0xabababab, etc.
1536   // Contained in new_space or old_space?   Check old_arena first since it's mostly empty.
1537   VectorSet *v = C->old_arena()->contains(n) ? old_space : new_space;
1538   if( v->test(n->_idx) ) return;
1539   if( (int)n->_idx == node_idx
1540       debug_only(|| n->debug_idx() == node_idx) ) {
1541     if (result != NULL)
1542       tty->print("find: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1543                  (uintptr_t)result, (uintptr_t)n, node_idx);
1544     result = n;
1545   }
1546   v->set(n->_idx);
1547   for( uint i=0; i<n->len(); i++ ) {
1548     if( only_ctrl && !(n->is_Region()) && (n->Opcode() != Op_Root) && (i != TypeFunc::Control) ) continue;
1549     find_recur(C, result, n->in(i), idx, only_ctrl, old_space, new_space );
1550   }
1551   // Search along forward edges also:
1552   if (idx < 0 && !only_ctrl) {
1553     for( uint j=0; j<n->outcnt(); j++ ) {
1554       find_recur(C, result, n->raw_out(j), idx, only_ctrl, old_space, new_space );
1555     }
1556   }
1557 #ifdef ASSERT
1558   // Search along debug_orig edges last, checking for cycles
1559   Node* orig = n->debug_orig();
1560   if (orig != NULL) {
1561     do {
1562       if (NotANode(orig))  break;
1563       find_recur(C, result, orig, idx, only_ctrl, old_space, new_space );
1564       orig = orig->debug_orig();
1565     } while (orig != NULL && orig != n->debug_orig());
1566   }
1567 #endif //ASSERT
1568 }
1569 
1570 // call this from debugger:
1571 Node* find_node(Node* n, int idx) {
1572   return n->find(idx);
1573 }
1574 
1575 //------------------------------find-------------------------------------------
1576 Node* Node::find(int idx) const {
1577   ResourceArea *area = Thread::current()->resource_area();
1578   VectorSet old_space(area), new_space(area);
1579   Node* result = NULL;
1580   find_recur(Compile::current(), result, (Node*) this, idx, false, &old_space, &new_space );
1581   return result;
1582 }
1583 
1584 //------------------------------find_ctrl--------------------------------------
1585 // Find an ancestor to this node in the control history with given _idx
1586 Node* Node::find_ctrl(int idx) const {
1587   ResourceArea *area = Thread::current()->resource_area();
1588   VectorSet old_space(area), new_space(area);
1589   Node* result = NULL;
1590   find_recur(Compile::current(), result, (Node*) this, idx, true, &old_space, &new_space );
1591   return result;
1592 }
1593 #endif
1594 
1595 
1596 
1597 #ifndef PRODUCT
1598 
1599 // -----------------------------Name-------------------------------------------
1600 extern const char *NodeClassNames[];
1601 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
1602 
1603 static bool is_disconnected(const Node* n) {
1604   for (uint i = 0; i < n->req(); i++) {
1605     if (n->in(i) != NULL)  return false;
1606   }
1607   return true;
1608 }
1609 
1610 #ifdef ASSERT
1611 static void dump_orig(Node* orig, outputStream *st) {
1612   Compile* C = Compile::current();
1613   if (NotANode(orig)) orig = NULL;
1614   if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1615   if (orig == NULL) return;
1616   st->print(" !orig=");
1617   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
1618   if (NotANode(fast)) fast = NULL;
1619   while (orig != NULL) {
1620     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
1621     if (discon) st->print("[");
1622     if (!Compile::current()->node_arena()->contains(orig))
1623       st->print("o");
1624     st->print("%d", orig->_idx);
1625     if (discon) st->print("]");
1626     orig = orig->debug_orig();
1627     if (NotANode(orig)) orig = NULL;
1628     if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1629     if (orig != NULL) st->print(",");
1630     if (fast != NULL) {
1631       // Step fast twice for each single step of orig:
1632       fast = fast->debug_orig();
1633       if (NotANode(fast)) fast = NULL;
1634       if (fast != NULL && fast != orig) {
1635         fast = fast->debug_orig();
1636         if (NotANode(fast)) fast = NULL;
1637       }
1638       if (fast == orig) {
1639         st->print("...");
1640         break;
1641       }
1642     }
1643   }
1644 }
1645 
1646 void Node::set_debug_orig(Node* orig) {
1647   _debug_orig = orig;
1648   if (BreakAtNode == 0)  return;
1649   if (NotANode(orig))  orig = NULL;
1650   int trip = 10;
1651   while (orig != NULL) {
1652     if (orig->debug_idx() == BreakAtNode || (int)orig->_idx == BreakAtNode) {
1653       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d orig._idx=%d orig._debug_idx=%d",
1654                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
1655       BREAKPOINT;
1656     }
1657     orig = orig->debug_orig();
1658     if (NotANode(orig))  orig = NULL;
1659     if (trip-- <= 0)  break;
1660   }
1661 }
1662 #endif //ASSERT
1663 
1664 //------------------------------dump------------------------------------------
1665 // Dump a Node
1666 void Node::dump(const char* suffix, bool mark, outputStream *st) const {
1667   Compile* C = Compile::current();
1668   bool is_new = C->node_arena()->contains(this);
1669   C->_in_dump_cnt++;
1670   st->print("%c%d%s\t%s\t=== ", is_new ? ' ' : 'o', _idx, mark ? " >" : "", Name());
1671 
1672   // Dump the required and precedence inputs
1673   dump_req(st);
1674   dump_prec(st);
1675   // Dump the outputs
1676   dump_out(st);
1677 
1678   if (is_disconnected(this)) {
1679 #ifdef ASSERT
1680     st->print("  [%d]",debug_idx());
1681     dump_orig(debug_orig(), st);
1682 #endif
1683     st->cr();
1684     C->_in_dump_cnt--;
1685     return;                     // don't process dead nodes
1686   }
1687 
1688   if (C->clone_map().value(_idx) != 0) {
1689     C->clone_map().dump(_idx);
1690   }
1691   // Dump node-specific info
1692   dump_spec(st);
1693 #ifdef ASSERT
1694   // Dump the non-reset _debug_idx
1695   if (Verbose && WizardMode) {
1696     st->print("  [%d]",debug_idx());
1697   }
1698 #endif
1699 
1700   const Type *t = bottom_type();
1701 
1702   if (t != NULL && (t->isa_instptr() || t->isa_klassptr())) {
1703     const TypeInstPtr  *toop = t->isa_instptr();
1704     const TypeKlassPtr *tkls = t->isa_klassptr();
1705     ciKlass*           klass = toop ? toop->klass() : (tkls ? tkls->klass() : NULL );
1706     if (klass && klass->is_loaded() && klass->is_interface()) {
1707       st->print("  Interface:");
1708     } else if (toop) {
1709       st->print("  Oop:");
1710     } else if (tkls) {
1711       st->print("  Klass:");
1712     }
1713     t->dump_on(st);
1714   } else if (t == Type::MEMORY) {
1715     st->print("  Memory:");
1716     MemNode::dump_adr_type(this, adr_type(), st);
1717   } else if (Verbose || WizardMode) {
1718     st->print("  Type:");
1719     if (t) {
1720       t->dump_on(st);
1721     } else {
1722       st->print("no type");
1723     }
1724   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
1725     // Dump MachSpillcopy vector type.
1726     t->dump_on(st);
1727   }
1728   if (is_new) {
1729     debug_only(dump_orig(debug_orig(), st));
1730     Node_Notes* nn = C->node_notes_at(_idx);
1731     if (nn != NULL && !nn->is_clear()) {
1732       if (nn->jvms() != NULL) {
1733         st->print(" !jvms:");
1734         nn->jvms()->dump_spec(st);
1735       }
1736     }
1737   }
1738   if (suffix) st->print("%s", suffix);
1739   C->_in_dump_cnt--;
1740 }
1741 
1742 //------------------------------dump_req--------------------------------------
1743 void Node::dump_req(outputStream *st) const {
1744   // Dump the required input edges
1745   for (uint i = 0; i < req(); i++) {    // For all required inputs
1746     Node* d = in(i);
1747     if (d == NULL) {
1748       st->print("_ ");
1749     } else if (NotANode(d)) {
1750       st->print("NotANode ");  // uninitialized, sentinel, garbage, etc.
1751     } else {
1752       st->print("%c%d ", Compile::current()->node_arena()->contains(d) ? ' ' : 'o', d->_idx);
1753     }
1754   }
1755 }
1756 
1757 
1758 //------------------------------dump_prec-------------------------------------
1759 void Node::dump_prec(outputStream *st) const {
1760   // Dump the precedence edges
1761   int any_prec = 0;
1762   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
1763     Node* p = in(i);
1764     if (p != NULL) {
1765       if (!any_prec++) st->print(" |");
1766       if (NotANode(p)) { st->print("NotANode "); continue; }
1767       st->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
1768     }
1769   }
1770 }
1771 
1772 //------------------------------dump_out--------------------------------------
1773 void Node::dump_out(outputStream *st) const {
1774   // Delimit the output edges
1775   st->print(" [[");
1776   // Dump the output edges
1777   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
1778     Node* u = _out[i];
1779     if (u == NULL) {
1780       st->print("_ ");
1781     } else if (NotANode(u)) {
1782       st->print("NotANode ");
1783     } else {
1784       st->print("%c%d ", Compile::current()->node_arena()->contains(u) ? ' ' : 'o', u->_idx);
1785     }
1786   }
1787   st->print("]] ");
1788 }
1789 
1790 //----------------------------collect_nodes_i----------------------------------
1791 // Collects nodes from an Ideal graph, starting from a given start node and
1792 // moving in a given direction until a certain depth (distance from the start
1793 // node) is reached. Duplicates are ignored.
1794 // Arguments:
1795 //   nstack:        the nodes are collected into this array.
1796 //   start:         the node at which to start collecting.
1797 //   direction:     if this is a positive number, collect input nodes; if it is
1798 //                  a negative number, collect output nodes.
1799 //   depth:         collect nodes up to this distance from the start node.
1800 //   include_start: whether to include the start node in the result collection.
1801 //   only_ctrl:     whether to regard control edges only during traversal.
1802 //   only_data:     whether to regard data edges only during traversal.
1803 static void collect_nodes_i(GrowableArray<Node*> *nstack, const Node* start, int direction, uint depth, bool include_start, bool only_ctrl, bool only_data) {
1804   Node* s = (Node*) start; // remove const
1805   nstack->append(s);
1806   int begin = 0;
1807   int end = 0;
1808   for(uint i = 0; i < depth; i++) {
1809     end = nstack->length();
1810     for(int j = begin; j < end; j++) {
1811       Node* tp  = nstack->at(j);
1812       uint limit = direction > 0 ? tp->len() : tp->outcnt();
1813       for(uint k = 0; k < limit; k++) {
1814         Node* n = direction > 0 ? tp->in(k) : tp->raw_out(k);
1815 
1816         if (NotANode(n))  continue;
1817         // do not recurse through top or the root (would reach unrelated stuff)
1818         if (n->is_Root() || n->is_top()) continue;
1819         if (only_ctrl && !n->is_CFG()) continue;
1820         if (only_data && n->is_CFG()) continue;
1821 
1822         bool on_stack = nstack->contains(n);
1823         if (!on_stack) {
1824           nstack->append(n);
1825         }
1826       }
1827     }
1828     begin = end;
1829   }
1830   if (!include_start) {
1831     nstack->remove(s);
1832   }
1833 }
1834 
1835 //------------------------------dump_nodes-------------------------------------
1836 static void dump_nodes(const Node* start, int d, bool only_ctrl) {
1837   if (NotANode(start)) return;
1838 
1839   GrowableArray <Node *> nstack(Compile::current()->live_nodes());
1840   collect_nodes_i(&nstack, start, d, (uint) ABS(d), true, only_ctrl, false);
1841 
1842   int end = nstack.length();
1843   if (d > 0) {
1844     for(int j = end-1; j >= 0; j--) {
1845       nstack.at(j)->dump();
1846     }
1847   } else {
1848     for(int j = 0; j < end; j++) {
1849       nstack.at(j)->dump();
1850     }
1851   }
1852 }
1853 
1854 //------------------------------dump-------------------------------------------
1855 void Node::dump(int d) const {
1856   dump_nodes(this, d, false);
1857 }
1858 
1859 //------------------------------dump_ctrl--------------------------------------
1860 // Dump a Node's control history to depth
1861 void Node::dump_ctrl(int d) const {
1862   dump_nodes(this, d, true);
1863 }
1864 
1865 //-----------------------------dump_compact------------------------------------
1866 void Node::dump_comp() const {
1867   this->dump_comp("\n");
1868 }
1869 
1870 //-----------------------------dump_compact------------------------------------
1871 // Dump a Node in compact representation, i.e., just print its name and index.
1872 // Nodes can specify additional specifics to print in compact representation by
1873 // implementing dump_compact_spec.
1874 void Node::dump_comp(const char* suffix, outputStream *st) const {
1875   Compile* C = Compile::current();
1876   C->_in_dump_cnt++;
1877   st->print("%s(%d)", Name(), _idx);
1878   this->dump_compact_spec(st);
1879   if (suffix) {
1880     st->print("%s", suffix);
1881   }
1882   C->_in_dump_cnt--;
1883 }
1884 
1885 //----------------------------dump_related-------------------------------------
1886 // Dump a Node's related nodes - the notion of "related" depends on the Node at
1887 // hand and is determined by the implementation of the virtual method rel.
1888 void Node::dump_related() const {
1889   Compile* C = Compile::current();
1890   GrowableArray <Node *> in_rel(C->unique());
1891   GrowableArray <Node *> out_rel(C->unique());
1892   this->related(&in_rel, &out_rel, false);
1893   for (int i = in_rel.length() - 1; i >= 0; i--) {
1894     in_rel.at(i)->dump();
1895   }
1896   this->dump("\n", true);
1897   for (int i = 0; i < out_rel.length(); i++) {
1898     out_rel.at(i)->dump();
1899   }
1900 }
1901 
1902 //----------------------------dump_related-------------------------------------
1903 // Dump a Node's related nodes up to a given depth (distance from the start
1904 // node).
1905 // Arguments:
1906 //   d_in:  depth for input nodes.
1907 //   d_out: depth for output nodes (note: this also is a positive number).
1908 void Node::dump_related(uint d_in, uint d_out) const {
1909   Compile* C = Compile::current();
1910   GrowableArray <Node *> in_rel(C->unique());
1911   GrowableArray <Node *> out_rel(C->unique());
1912 
1913   // call collect_nodes_i directly
1914   collect_nodes_i(&in_rel, this, 1, d_in, false, false, false);
1915   collect_nodes_i(&out_rel, this, -1, d_out, false, false, false);
1916 
1917   for (int i = in_rel.length() - 1; i >= 0; i--) {
1918     in_rel.at(i)->dump();
1919   }
1920   this->dump("\n", true);
1921   for (int i = 0; i < out_rel.length(); i++) {
1922     out_rel.at(i)->dump();
1923   }
1924 }
1925 
1926 //------------------------dump_related_compact---------------------------------
1927 // Dump a Node's related nodes in compact representation. The notion of
1928 // "related" depends on the Node at hand and is determined by the implementation
1929 // of the virtual method rel.
1930 void Node::dump_related_compact() const {
1931   Compile* C = Compile::current();
1932   GrowableArray <Node *> in_rel(C->unique());
1933   GrowableArray <Node *> out_rel(C->unique());
1934   this->related(&in_rel, &out_rel, true);
1935   int n_in = in_rel.length();
1936   int n_out = out_rel.length();
1937 
1938   this->dump_comp(n_in == 0 ? "\n" : "  ");
1939   for (int i = 0; i < n_in; i++) {
1940     in_rel.at(i)->dump_comp(i == n_in - 1 ? "\n" : "  ");
1941   }
1942   for (int i = 0; i < n_out; i++) {
1943     out_rel.at(i)->dump_comp(i == n_out - 1 ? "\n" : "  ");
1944   }
1945 }
1946 
1947 //------------------------------related----------------------------------------
1948 // Collect a Node's related nodes. The default behaviour just collects the
1949 // inputs and outputs at depth 1, including both control and data flow edges,
1950 // regardless of whether the presentation is compact or not. For data nodes,
1951 // the default is to collect all data inputs (till level 1 if compact), and
1952 // outputs till level 1.
1953 void Node::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
1954   if (this->is_CFG()) {
1955     collect_nodes_i(in_rel, this, 1, 1, false, false, false);
1956     collect_nodes_i(out_rel, this, -1, 1, false, false, false);
1957   } else {
1958     if (compact) {
1959       this->collect_nodes(in_rel, 1, false, true);
1960     } else {
1961       this->collect_nodes_in_all_data(in_rel, false);
1962     }
1963     this->collect_nodes(out_rel, -1, false, false);
1964   }
1965 }
1966 
1967 //---------------------------collect_nodes-------------------------------------
1968 // An entry point to the low-level node collection facility, to start from a
1969 // given node in the graph. The start node is by default not included in the
1970 // result.
1971 // Arguments:
1972 //   ns:   collect the nodes into this data structure.
1973 //   d:    the depth (distance from start node) to which nodes should be
1974 //         collected. A value >0 indicates input nodes, a value <0, output
1975 //         nodes.
1976 //   ctrl: include only control nodes.
1977 //   data: include only data nodes.
1978 void Node::collect_nodes(GrowableArray<Node*> *ns, int d, bool ctrl, bool data) const {
1979   if (ctrl && data) {
1980     // ignore nonsensical combination
1981     return;
1982   }
1983   collect_nodes_i(ns, this, d, (uint) ABS(d), false, ctrl, data);
1984 }
1985 
1986 //--------------------------collect_nodes_in-----------------------------------
1987 static void collect_nodes_in(Node* start, GrowableArray<Node*> *ns, bool primary_is_data, bool collect_secondary) {
1988   // The maximum depth is determined using a BFS that visits all primary (data
1989   // or control) inputs and increments the depth at each level.
1990   uint d_in = 0;
1991   GrowableArray<Node*> nodes(Compile::current()->unique());
1992   nodes.push(start);
1993   int nodes_at_current_level = 1;
1994   int n_idx = 0;
1995   while (nodes_at_current_level > 0) {
1996     // Add all primary inputs reachable from the current level to the list, and
1997     // increase the depth if there were any.
1998     int nodes_at_next_level = 0;
1999     bool nodes_added = false;
2000     while (nodes_at_current_level > 0) {
2001       nodes_at_current_level--;
2002       Node* current = nodes.at(n_idx++);
2003       for (uint i = 0; i < current->len(); i++) {
2004         Node* n = current->in(i);
2005         if (NotANode(n)) {
2006           continue;
2007         }
2008         if ((primary_is_data && n->is_CFG()) || (!primary_is_data && !n->is_CFG())) {
2009           continue;
2010         }
2011         if (!nodes.contains(n)) {
2012           nodes.push(n);
2013           nodes_added = true;
2014           nodes_at_next_level++;
2015         }
2016       }
2017     }
2018     if (nodes_added) {
2019       d_in++;
2020     }
2021     nodes_at_current_level = nodes_at_next_level;
2022   }
2023   start->collect_nodes(ns, d_in, !primary_is_data, primary_is_data);
2024   if (collect_secondary) {
2025     // Now, iterate over the secondary nodes in ns and add the respective
2026     // boundary reachable from them.
2027     GrowableArray<Node*> sns(Compile::current()->unique());
2028     for (GrowableArrayIterator<Node*> it = ns->begin(); it != ns->end(); ++it) {
2029       Node* n = *it;
2030       n->collect_nodes(&sns, 1, primary_is_data, !primary_is_data);
2031       for (GrowableArrayIterator<Node*> d = sns.begin(); d != sns.end(); ++d) {
2032         ns->append_if_missing(*d);
2033       }
2034       sns.clear();
2035     }
2036   }
2037 }
2038 
2039 //---------------------collect_nodes_in_all_data-------------------------------
2040 // Collect the entire data input graph. Include the control boundary if
2041 // requested.
2042 // Arguments:
2043 //   ns:   collect the nodes into this data structure.
2044 //   ctrl: if true, include the control boundary.
2045 void Node::collect_nodes_in_all_data(GrowableArray<Node*> *ns, bool ctrl) const {
2046   collect_nodes_in((Node*) this, ns, true, ctrl);
2047 }
2048 
2049 //--------------------------collect_nodes_in_all_ctrl--------------------------
2050 // Collect the entire control input graph. Include the data boundary if
2051 // requested.
2052 //   ns:   collect the nodes into this data structure.
2053 //   data: if true, include the control boundary.
2054 void Node::collect_nodes_in_all_ctrl(GrowableArray<Node*> *ns, bool data) const {
2055   collect_nodes_in((Node*) this, ns, false, data);
2056 }
2057 
2058 //------------------collect_nodes_out_all_ctrl_boundary------------------------
2059 // Collect the entire output graph until hitting control node boundaries, and
2060 // include those.
2061 void Node::collect_nodes_out_all_ctrl_boundary(GrowableArray<Node*> *ns) const {
2062   // Perform a BFS and stop at control nodes.
2063   GrowableArray<Node*> nodes(Compile::current()->unique());
2064   nodes.push((Node*) this);
2065   while (nodes.length() > 0) {
2066     Node* current = nodes.pop();
2067     if (NotANode(current)) {
2068       continue;
2069     }
2070     ns->append_if_missing(current);
2071     if (!current->is_CFG()) {
2072       for (DUIterator i = current->outs(); current->has_out(i); i++) {
2073         nodes.push(current->out(i));
2074       }
2075     }
2076   }
2077   ns->remove((Node*) this);
2078 }
2079 
2080 // VERIFICATION CODE
2081 // For each input edge to a node (ie - for each Use-Def edge), verify that
2082 // there is a corresponding Def-Use edge.
2083 //------------------------------verify_edges-----------------------------------
2084 void Node::verify_edges(Unique_Node_List &visited) {
2085   uint i, j, idx;
2086   int  cnt;
2087   Node *n;
2088 
2089   // Recursive termination test
2090   if (visited.member(this))  return;
2091   visited.push(this);
2092 
2093   // Walk over all input edges, checking for correspondence
2094   for( i = 0; i < len(); i++ ) {
2095     n = in(i);
2096     if (n != NULL && !n->is_top()) {
2097       // Count instances of (Node *)this
2098       cnt = 0;
2099       for (idx = 0; idx < n->_outcnt; idx++ ) {
2100         if (n->_out[idx] == (Node *)this)  cnt++;
2101       }
2102       assert( cnt > 0,"Failed to find Def-Use edge." );
2103       // Check for duplicate edges
2104       // walk the input array downcounting the input edges to n
2105       for( j = 0; j < len(); j++ ) {
2106         if( in(j) == n ) cnt--;
2107       }
2108       assert( cnt == 0,"Mismatched edge count.");
2109     } else if (n == NULL) {
2110       assert(i >= req() || i == 0 || is_Region() || is_Phi(), "only regions or phis have null data edges");
2111     } else {
2112       assert(n->is_top(), "sanity");
2113       // Nothing to check.
2114     }
2115   }
2116   // Recursive walk over all input edges
2117   for( i = 0; i < len(); i++ ) {
2118     n = in(i);
2119     if( n != NULL )
2120       in(i)->verify_edges(visited);
2121   }
2122 }
2123 
2124 //------------------------------verify_recur-----------------------------------
2125 static const Node *unique_top = NULL;
2126 
2127 void Node::verify_recur(const Node *n, int verify_depth,
2128                         VectorSet &old_space, VectorSet &new_space) {
2129   if ( verify_depth == 0 )  return;
2130   if (verify_depth > 0)  --verify_depth;
2131 
2132   Compile* C = Compile::current();
2133 
2134   // Contained in new_space or old_space?
2135   VectorSet *v = C->node_arena()->contains(n) ? &new_space : &old_space;
2136   // Check for visited in the proper space.  Numberings are not unique
2137   // across spaces so we need a separate VectorSet for each space.
2138   if( v->test_set(n->_idx) ) return;
2139 
2140   if (n->is_Con() && n->bottom_type() == Type::TOP) {
2141     if (C->cached_top_node() == NULL)
2142       C->set_cached_top_node((Node*)n);
2143     assert(C->cached_top_node() == n, "TOP node must be unique");
2144   }
2145 
2146   for( uint i = 0; i < n->len(); i++ ) {
2147     Node *x = n->in(i);
2148     if (!x || x->is_top()) continue;
2149 
2150     // Verify my input has a def-use edge to me
2151     if (true /*VerifyDefUse*/) {
2152       // Count use-def edges from n to x
2153       int cnt = 0;
2154       for( uint j = 0; j < n->len(); j++ )
2155         if( n->in(j) == x )
2156           cnt++;
2157       // Count def-use edges from x to n
2158       uint max = x->_outcnt;
2159       for( uint k = 0; k < max; k++ )
2160         if (x->_out[k] == n)
2161           cnt--;
2162       assert( cnt == 0, "mismatched def-use edge counts" );
2163     }
2164 
2165     verify_recur(x, verify_depth, old_space, new_space);
2166   }
2167 
2168 }
2169 
2170 //------------------------------verify-----------------------------------------
2171 // Check Def-Use info for my subgraph
2172 void Node::verify() const {
2173   Compile* C = Compile::current();
2174   Node* old_top = C->cached_top_node();
2175   ResourceMark rm;
2176   ResourceArea *area = Thread::current()->resource_area();
2177   VectorSet old_space(area), new_space(area);
2178   verify_recur(this, -1, old_space, new_space);
2179   C->set_cached_top_node(old_top);
2180 }
2181 #endif
2182 
2183 
2184 //------------------------------walk-------------------------------------------
2185 // Graph walk, with both pre-order and post-order functions
2186 void Node::walk(NFunc pre, NFunc post, void *env) {
2187   VectorSet visited(Thread::current()->resource_area()); // Setup for local walk
2188   walk_(pre, post, env, visited);
2189 }
2190 
2191 void Node::walk_(NFunc pre, NFunc post, void *env, VectorSet &visited) {
2192   if( visited.test_set(_idx) ) return;
2193   pre(*this,env);               // Call the pre-order walk function
2194   for( uint i=0; i<_max; i++ )
2195     if( in(i) )                 // Input exists and is not walked?
2196       in(i)->walk_(pre,post,env,visited); // Walk it with pre & post functions
2197   post(*this,env);              // Call the post-order walk function
2198 }
2199 
2200 void Node::nop(Node &, void*) {}
2201 
2202 //------------------------------Registers--------------------------------------
2203 // Do we Match on this edge index or not?  Generally false for Control
2204 // and true for everything else.  Weird for calls & returns.
2205 uint Node::match_edge(uint idx) const {
2206   return idx;                   // True for other than index 0 (control)
2207 }
2208 
2209 static RegMask _not_used_at_all;
2210 // Register classes are defined for specific machines
2211 const RegMask &Node::out_RegMask() const {
2212   ShouldNotCallThis();
2213   return _not_used_at_all;
2214 }
2215 
2216 const RegMask &Node::in_RegMask(uint) const {
2217   ShouldNotCallThis();
2218   return _not_used_at_all;
2219 }
2220 
2221 //=============================================================================
2222 //-----------------------------------------------------------------------------
2223 void Node_Array::reset( Arena *new_arena ) {
2224   _a->Afree(_nodes,_max*sizeof(Node*));
2225   _max   = 0;
2226   _nodes = NULL;
2227   _a     = new_arena;
2228 }
2229 
2230 //------------------------------clear------------------------------------------
2231 // Clear all entries in _nodes to NULL but keep storage
2232 void Node_Array::clear() {
2233   Copy::zero_to_bytes( _nodes, _max*sizeof(Node*) );
2234 }
2235 
2236 //-----------------------------------------------------------------------------
2237 void Node_Array::grow( uint i ) {
2238   if( !_max ) {
2239     _max = 1;
2240     _nodes = (Node**)_a->Amalloc( _max * sizeof(Node*) );
2241     _nodes[0] = NULL;
2242   }
2243   uint old = _max;
2244   while( i >= _max ) _max <<= 1;        // Double to fit
2245   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2246   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2247 }
2248 
2249 //-----------------------------------------------------------------------------
2250 void Node_Array::insert( uint i, Node *n ) {
2251   if( _nodes[_max-1] ) grow(_max);      // Get more space if full
2252   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i+1], ((_max-i-1)*sizeof(Node*)));
2253   _nodes[i] = n;
2254 }
2255 
2256 //-----------------------------------------------------------------------------
2257 void Node_Array::remove( uint i ) {
2258   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i+1], (HeapWord*)&_nodes[i], ((_max-i-1)*sizeof(Node*)));
2259   _nodes[_max-1] = NULL;
2260 }
2261 
2262 //-----------------------------------------------------------------------------
2263 void Node_Array::sort( C_sort_func_t func) {
2264   qsort( _nodes, _max, sizeof( Node* ), func );
2265 }
2266 
2267 //-----------------------------------------------------------------------------
2268 void Node_Array::dump() const {
2269 #ifndef PRODUCT
2270   for( uint i = 0; i < _max; i++ ) {
2271     Node *nn = _nodes[i];
2272     if( nn != NULL ) {
2273       tty->print("%5d--> ",i); nn->dump();
2274     }
2275   }
2276 #endif
2277 }
2278 
2279 //--------------------------is_iteratively_computed------------------------------
2280 // Operation appears to be iteratively computed (such as an induction variable)
2281 // It is possible for this operation to return false for a loop-varying
2282 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2283 bool Node::is_iteratively_computed() {
2284   if (ideal_reg()) { // does operation have a result register?
2285     for (uint i = 1; i < req(); i++) {
2286       Node* n = in(i);
2287       if (n != NULL && n->is_Phi()) {
2288         for (uint j = 1; j < n->req(); j++) {
2289           if (n->in(j) == this) {
2290             return true;
2291           }
2292         }
2293       }
2294     }
2295   }
2296   return false;
2297 }
2298 
2299 //--------------------------find_similar------------------------------
2300 // Return a node with opcode "opc" and same inputs as "this" if one can
2301 // be found; Otherwise return NULL;
2302 Node* Node::find_similar(int opc) {
2303   if (req() >= 2) {
2304     Node* def = in(1);
2305     if (def && def->outcnt() >= 2) {
2306       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2307         Node* use = def->fast_out(i);
2308         if (use->Opcode() == opc &&
2309             use->req() == req()) {
2310           uint j;
2311           for (j = 0; j < use->req(); j++) {
2312             if (use->in(j) != in(j)) {
2313               break;
2314             }
2315           }
2316           if (j == use->req()) {
2317             return use;
2318           }
2319         }
2320       }
2321     }
2322   }
2323   return NULL;
2324 }
2325 
2326 
2327 //--------------------------unique_ctrl_out------------------------------
2328 // Return the unique control out if only one. Null if none or more than one.
2329 Node* Node::unique_ctrl_out() const {
2330   Node* found = NULL;
2331   for (uint i = 0; i < outcnt(); i++) {
2332     Node* use = raw_out(i);
2333     if (use->is_CFG() && use != this) {
2334       if (found != NULL) return NULL;
2335       found = use;
2336     }
2337   }
2338   return found;
2339 }
2340 
2341 void Node::ensure_control_or_add_prec(Node* c) {
2342   if (in(0) == NULL) {
2343     set_req(0, c);
2344   } else if (in(0) != c) {
2345     add_prec(c);
2346   }
2347 }
2348 
2349 //=============================================================================
2350 //------------------------------yank-------------------------------------------
2351 // Find and remove
2352 void Node_List::yank( Node *n ) {
2353   uint i;
2354   for( i = 0; i < _cnt; i++ )
2355     if( _nodes[i] == n )
2356       break;
2357 
2358   if( i < _cnt )
2359     _nodes[i] = _nodes[--_cnt];
2360 }
2361 
2362 //------------------------------dump-------------------------------------------
2363 void Node_List::dump() const {
2364 #ifndef PRODUCT
2365   for( uint i = 0; i < _cnt; i++ )
2366     if( _nodes[i] ) {
2367       tty->print("%5d--> ",i);
2368       _nodes[i]->dump();
2369     }
2370 #endif
2371 }
2372 
2373 void Node_List::dump_simple() const {
2374 #ifndef PRODUCT
2375   for( uint i = 0; i < _cnt; i++ )
2376     if( _nodes[i] ) {
2377       tty->print(" %d", _nodes[i]->_idx);
2378     } else {
2379       tty->print(" NULL");
2380     }
2381 #endif
2382 }
2383 
2384 //=============================================================================
2385 //------------------------------remove-----------------------------------------
2386 void Unique_Node_List::remove( Node *n ) {
2387   if( _in_worklist[n->_idx] ) {
2388     for( uint i = 0; i < size(); i++ )
2389       if( _nodes[i] == n ) {
2390         map(i,Node_List::pop());
2391         _in_worklist >>= n->_idx;
2392         return;
2393       }
2394     ShouldNotReachHere();
2395   }
2396 }
2397 
2398 //-----------------------remove_useless_nodes----------------------------------
2399 // Remove useless nodes from worklist
2400 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2401 
2402   for( uint i = 0; i < size(); ++i ) {
2403     Node *n = at(i);
2404     assert( n != NULL, "Did not expect null entries in worklist");
2405     if( ! useful.test(n->_idx) ) {
2406       _in_worklist >>= n->_idx;
2407       map(i,Node_List::pop());
2408       // Node *replacement = Node_List::pop();
2409       // if( i != size() ) { // Check if removing last entry
2410       //   _nodes[i] = replacement;
2411       // }
2412       --i;  // Visit popped node
2413       // If it was last entry, loop terminates since size() was also reduced
2414     }
2415   }
2416 }
2417 
2418 //=============================================================================
2419 void Node_Stack::grow() {
2420   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2421   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2422   size_t max = old_max << 1;             // max * 2
2423   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2424   _inode_max = _inodes + max;
2425   _inode_top = _inodes + old_top;        // restore _top
2426 }
2427 
2428 // Node_Stack is used to map nodes.
2429 Node* Node_Stack::find(uint idx) const {
2430   uint sz = size();
2431   for (uint i=0; i < sz; i++) {
2432     if (idx == index_at(i) )
2433       return node_at(i);
2434   }
2435   return NULL;
2436 }
2437 
2438 //=============================================================================
2439 uint TypeNode::size_of() const { return sizeof(*this); }
2440 #ifndef PRODUCT
2441 void TypeNode::dump_spec(outputStream *st) const {
2442   if( !Verbose && !WizardMode ) {
2443     // standard dump does this in Verbose and WizardMode
2444     st->print(" #"); _type->dump_on(st);
2445   }
2446 }
2447 
2448 void TypeNode::dump_compact_spec(outputStream *st) const {
2449   st->print("#");
2450   _type->dump_on(st);
2451 }
2452 #endif
2453 uint TypeNode::hash() const {
2454   return Node::hash() + _type->hash();
2455 }
2456 uint TypeNode::cmp( const Node &n ) const
2457 { return !Type::cmp( _type, ((TypeNode&)n)._type ); }
2458 const Type *TypeNode::bottom_type() const { return _type; }
2459 const Type* TypeNode::Value(PhaseGVN* phase) const { return _type; }
2460 
2461 //------------------------------ideal_reg--------------------------------------
2462 uint TypeNode::ideal_reg() const {
2463   return _type->ideal_reg();
2464 }
--- EOF ---