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