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