1 /*
   2  * Copyright (c) 1997, 2023, 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/ad.hpp"
  32 #include "opto/callGenerator.hpp"
  33 #include "opto/castnode.hpp"
  34 #include "opto/cfgnode.hpp"
  35 #include "opto/connode.hpp"
  36 #include "opto/loopnode.hpp"
  37 #include "opto/machnode.hpp"
  38 #include "opto/matcher.hpp"
  39 #include "opto/node.hpp"
  40 #include "opto/opcodes.hpp"
  41 #include "opto/regmask.hpp"
  42 #include "opto/rootnode.hpp"
  43 #include "opto/type.hpp"
  44 #include "utilities/copy.hpp"
  45 #include "utilities/macros.hpp"
  46 #include "utilities/powerOfTwo.hpp"
  47 #include "utilities/stringUtils.hpp"
  48 
  49 class RegMask;
  50 // #include "phase.hpp"
  51 class PhaseTransform;
  52 class PhaseGVN;
  53 
  54 // Arena we are currently building Nodes in
  55 const uint Node::NotAMachineReg = 0xffff0000;
  56 
  57 #ifndef PRODUCT
  58 extern uint nodes_created;
  59 #endif
  60 #ifdef __clang__
  61 #pragma clang diagnostic push
  62 #pragma GCC diagnostic ignored "-Wuninitialized"
  63 #endif
  64 
  65 #ifdef ASSERT
  66 
  67 //-------------------------- construct_node------------------------------------
  68 // Set a breakpoint here to identify where a particular node index is built.
  69 void Node::verify_construction() {
  70   _debug_orig = nullptr;
  71   // The decimal digits of _debug_idx are <compile_id> followed by 10 digits of <_idx>
  72   Compile* C = Compile::current();
  73   assert(C->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  74   uint64_t new_debug_idx = (uint64_t)C->compile_id() * 10000000000 + _idx;
  75   set_debug_idx(new_debug_idx);
  76   if (!C->phase_optimize_finished()) {
  77     // Only check assert during parsing and optimization phase. Skip it while generating code.
  78     assert(C->live_nodes() <= C->max_node_limit(), "Live Node limit exceeded limit");
  79   }
  80   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (uint64_t)_idx == BreakAtNode)) {
  81     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=" UINT64_FORMAT, _idx, _debug_idx);
  82     BREAKPOINT;
  83   }
  84 #if OPTO_DU_ITERATOR_ASSERT
  85   _last_del = nullptr;
  86   _del_tick = 0;
  87 #endif
  88   _hash_lock = 0;
  89 }
  90 
  91 
  92 // #ifdef ASSERT ...
  93 
  94 #if OPTO_DU_ITERATOR_ASSERT
  95 void DUIterator_Common::sample(const Node* node) {
  96   _vdui     = VerifyDUIterators;
  97   _node     = node;
  98   _outcnt   = node->_outcnt;
  99   _del_tick = node->_del_tick;
 100   _last     = nullptr;
 101 }
 102 
 103 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
 104   assert(_node     == node, "consistent iterator source");
 105   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
 106 }
 107 
 108 void DUIterator_Common::verify_resync() {
 109   // Ensure that the loop body has just deleted the last guy produced.
 110   const Node* node = _node;
 111   // Ensure that at least one copy of the last-seen edge was deleted.
 112   // Note:  It is OK to delete multiple copies of the last-seen edge.
 113   // Unfortunately, we have no way to verify that all the deletions delete
 114   // that same edge.  On this point we must use the Honor System.
 115   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 116   assert(node->_last_del == _last, "must have deleted the edge just produced");
 117   // We liked this deletion, so accept the resulting outcnt and tick.
 118   _outcnt   = node->_outcnt;
 119   _del_tick = node->_del_tick;
 120 }
 121 
 122 void DUIterator_Common::reset(const DUIterator_Common& that) {
 123   if (this == &that)  return;  // ignore assignment to self
 124   if (!_vdui) {
 125     // We need to initialize everything, overwriting garbage values.
 126     _last = that._last;
 127     _vdui = that._vdui;
 128   }
 129   // Note:  It is legal (though odd) for an iterator over some node x
 130   // to be reassigned to iterate over another node y.  Some doubly-nested
 131   // progress loops depend on being able to do this.
 132   const Node* node = that._node;
 133   // Re-initialize everything, except _last.
 134   _node     = node;
 135   _outcnt   = node->_outcnt;
 136   _del_tick = node->_del_tick;
 137 }
 138 
 139 void DUIterator::sample(const Node* node) {
 140   DUIterator_Common::sample(node);      // Initialize the assertion data.
 141   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 142 }
 143 
 144 void DUIterator::verify(const Node* node, bool at_end_ok) {
 145   DUIterator_Common::verify(node, at_end_ok);
 146   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 147 }
 148 
 149 void DUIterator::verify_increment() {
 150   if (_refresh_tick & 1) {
 151     // We have refreshed the index during this loop.
 152     // Fix up _idx to meet asserts.
 153     if (_idx > _outcnt)  _idx = _outcnt;
 154   }
 155   verify(_node, true);
 156 }
 157 
 158 void DUIterator::verify_resync() {
 159   // Note:  We do not assert on _outcnt, because insertions are OK here.
 160   DUIterator_Common::verify_resync();
 161   // Make sure we are still in sync, possibly with no more out-edges:
 162   verify(_node, true);
 163 }
 164 
 165 void DUIterator::reset(const DUIterator& that) {
 166   if (this == &that)  return;  // self assignment is always a no-op
 167   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 168   assert(that._idx          == 0, "assign only the result of Node::outs()");
 169   assert(_idx               == that._idx, "already assigned _idx");
 170   if (!_vdui) {
 171     // We need to initialize everything, overwriting garbage values.
 172     sample(that._node);
 173   } else {
 174     DUIterator_Common::reset(that);
 175     if (_refresh_tick & 1) {
 176       _refresh_tick++;                  // Clear the "was refreshed" flag.
 177     }
 178     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 179   }
 180 }
 181 
 182 void DUIterator::refresh() {
 183   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 184   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 185 }
 186 
 187 void DUIterator::verify_finish() {
 188   // If the loop has killed the node, do not require it to re-run.
 189   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 190   // If this assert triggers, it means that a loop used refresh_out_pos
 191   // to re-synch an iteration index, but the loop did not correctly
 192   // re-run itself, using a "while (progress)" construct.
 193   // This iterator enforces the rule that you must keep trying the loop
 194   // until it "runs clean" without any need for refreshing.
 195   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 196 }
 197 
 198 
 199 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 200   DUIterator_Common::verify(node, at_end_ok);
 201   Node** out    = node->_out;
 202   uint   cnt    = node->_outcnt;
 203   assert(cnt == _outcnt, "no insertions allowed");
 204   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 205   // This last check is carefully designed to work for NO_OUT_ARRAY.
 206 }
 207 
 208 void DUIterator_Fast::verify_limit() {
 209   const Node* node = _node;
 210   verify(node, true);
 211   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 212 }
 213 
 214 void DUIterator_Fast::verify_resync() {
 215   const Node* node = _node;
 216   if (_outp == node->_out + _outcnt) {
 217     // Note that the limit imax, not the pointer i, gets updated with the
 218     // exact count of deletions.  (For the pointer it's always "--i".)
 219     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 220     // This is a limit pointer, with a name like "imax".
 221     // Fudge the _last field so that the common assert will be happy.
 222     _last = (Node*) node->_last_del;
 223     DUIterator_Common::verify_resync();
 224   } else {
 225     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 226     // A normal internal pointer.
 227     DUIterator_Common::verify_resync();
 228     // Make sure we are still in sync, possibly with no more out-edges:
 229     verify(node, true);
 230   }
 231 }
 232 
 233 void DUIterator_Fast::verify_relimit(uint n) {
 234   const Node* node = _node;
 235   assert((int)n > 0, "use imax -= n only with a positive count");
 236   // This must be a limit pointer, with a name like "imax".
 237   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 238   // The reported number of deletions must match what the node saw.
 239   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 240   // Fudge the _last field so that the common assert will be happy.
 241   _last = (Node*) node->_last_del;
 242   DUIterator_Common::verify_resync();
 243 }
 244 
 245 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 246   assert(_outp              == that._outp, "already assigned _outp");
 247   DUIterator_Common::reset(that);
 248 }
 249 
 250 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 251   // at_end_ok means the _outp is allowed to underflow by 1
 252   _outp += at_end_ok;
 253   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 254   _outp -= at_end_ok;
 255   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 256 }
 257 
 258 void DUIterator_Last::verify_limit() {
 259   // Do not require the limit address to be resynched.
 260   //verify(node, true);
 261   assert(_outp == _node->_out, "limit still correct");
 262 }
 263 
 264 void DUIterator_Last::verify_step(uint num_edges) {
 265   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 266   _outcnt   -= num_edges;
 267   _del_tick += num_edges;
 268   // Make sure we are still in sync, possibly with no more out-edges:
 269   const Node* node = _node;
 270   verify(node, true);
 271   assert(node->_last_del == _last, "must have deleted the edge just produced");
 272 }
 273 
 274 #endif //OPTO_DU_ITERATOR_ASSERT
 275 
 276 
 277 #endif //ASSERT
 278 
 279 
 280 // This constant used to initialize _out may be any non-null value.
 281 // The value null is reserved for the top node only.
 282 #define NO_OUT_ARRAY ((Node**)-1)
 283 
 284 // Out-of-line code from node constructors.
 285 // Executed only when extra debug info. is being passed around.
 286 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 287   C->set_node_notes_at(idx, nn);
 288 }
 289 
 290 // Shared initialization code.
 291 inline int Node::Init(int req) {
 292   Compile* C = Compile::current();
 293   int idx = C->next_unique();
 294   NOT_PRODUCT(_igv_idx = C->next_igv_idx());
 295 
 296   // Allocate memory for the necessary number of edges.
 297   if (req > 0) {
 298     // Allocate space for _in array to have double alignment.
 299     _in = (Node **) ((char *) (C->node_arena()->AmallocWords(req * sizeof(void*))));
 300   }
 301   // If there are default notes floating around, capture them:
 302   Node_Notes* nn = C->default_node_notes();
 303   if (nn != nullptr)  init_node_notes(C, idx, nn);
 304 
 305   // Note:  At this point, C is dead,
 306   // and we begin to initialize the new Node.
 307 
 308   _cnt = _max = req;
 309   _outcnt = _outmax = 0;
 310   _class_id = Class_Node;
 311   _flags = 0;
 312   _out = NO_OUT_ARRAY;
 313   return idx;
 314 }
 315 
 316 //------------------------------Node-------------------------------------------
 317 // Create a Node, with a given number of required edges.
 318 Node::Node(uint req)
 319   : _idx(Init(req))
 320 #ifdef ASSERT
 321   , _parse_idx(_idx)
 322 #endif
 323 {
 324   assert( req < Compile::current()->max_node_limit() - NodeLimitFudgeFactor, "Input limit exceeded" );
 325   debug_only( verify_construction() );
 326   NOT_PRODUCT(nodes_created++);
 327   if (req == 0) {
 328     _in = nullptr;
 329   } else {
 330     Node** to = _in;
 331     for(uint i = 0; i < req; i++) {
 332       to[i] = nullptr;
 333     }
 334   }
 335 }
 336 
 337 //------------------------------Node-------------------------------------------
 338 Node::Node(Node *n0)
 339   : _idx(Init(1))
 340 #ifdef ASSERT
 341   , _parse_idx(_idx)
 342 #endif
 343 {
 344   debug_only( verify_construction() );
 345   NOT_PRODUCT(nodes_created++);
 346   assert( is_not_dead(n0), "can not use dead node");
 347   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 348 }
 349 
 350 //------------------------------Node-------------------------------------------
 351 Node::Node(Node *n0, Node *n1)
 352   : _idx(Init(2))
 353 #ifdef ASSERT
 354   , _parse_idx(_idx)
 355 #endif
 356 {
 357   debug_only( verify_construction() );
 358   NOT_PRODUCT(nodes_created++);
 359   assert( is_not_dead(n0), "can not use dead node");
 360   assert( is_not_dead(n1), "can not use dead node");
 361   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 362   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 363 }
 364 
 365 //------------------------------Node-------------------------------------------
 366 Node::Node(Node *n0, Node *n1, Node *n2)
 367   : _idx(Init(3))
 368 #ifdef ASSERT
 369   , _parse_idx(_idx)
 370 #endif
 371 {
 372   debug_only( verify_construction() );
 373   NOT_PRODUCT(nodes_created++);
 374   assert( is_not_dead(n0), "can not use dead node");
 375   assert( is_not_dead(n1), "can not use dead node");
 376   assert( is_not_dead(n2), "can not use dead node");
 377   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 378   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 379   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 380 }
 381 
 382 //------------------------------Node-------------------------------------------
 383 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 384   : _idx(Init(4))
 385 #ifdef ASSERT
 386   , _parse_idx(_idx)
 387 #endif
 388 {
 389   debug_only( verify_construction() );
 390   NOT_PRODUCT(nodes_created++);
 391   assert( is_not_dead(n0), "can not use dead node");
 392   assert( is_not_dead(n1), "can not use dead node");
 393   assert( is_not_dead(n2), "can not use dead node");
 394   assert( is_not_dead(n3), "can not use dead node");
 395   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 396   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 397   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 398   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 399 }
 400 
 401 //------------------------------Node-------------------------------------------
 402 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 403   : _idx(Init(5))
 404 #ifdef ASSERT
 405   , _parse_idx(_idx)
 406 #endif
 407 {
 408   debug_only( verify_construction() );
 409   NOT_PRODUCT(nodes_created++);
 410   assert( is_not_dead(n0), "can not use dead node");
 411   assert( is_not_dead(n1), "can not use dead node");
 412   assert( is_not_dead(n2), "can not use dead node");
 413   assert( is_not_dead(n3), "can not use dead node");
 414   assert( is_not_dead(n4), "can not use dead node");
 415   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 416   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 417   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 418   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 419   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 420 }
 421 
 422 //------------------------------Node-------------------------------------------
 423 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 424                      Node *n4, Node *n5)
 425   : _idx(Init(6))
 426 #ifdef ASSERT
 427   , _parse_idx(_idx)
 428 #endif
 429 {
 430   debug_only( verify_construction() );
 431   NOT_PRODUCT(nodes_created++);
 432   assert( is_not_dead(n0), "can not use dead node");
 433   assert( is_not_dead(n1), "can not use dead node");
 434   assert( is_not_dead(n2), "can not use dead node");
 435   assert( is_not_dead(n3), "can not use dead node");
 436   assert( is_not_dead(n4), "can not use dead node");
 437   assert( is_not_dead(n5), "can not use dead node");
 438   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 439   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 440   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 441   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 442   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 443   _in[5] = n5; if (n5 != nullptr) n5->add_out((Node *)this);
 444 }
 445 
 446 //------------------------------Node-------------------------------------------
 447 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 448                      Node *n4, Node *n5, Node *n6)
 449   : _idx(Init(7))
 450 #ifdef ASSERT
 451   , _parse_idx(_idx)
 452 #endif
 453 {
 454   debug_only( verify_construction() );
 455   NOT_PRODUCT(nodes_created++);
 456   assert( is_not_dead(n0), "can not use dead node");
 457   assert( is_not_dead(n1), "can not use dead node");
 458   assert( is_not_dead(n2), "can not use dead node");
 459   assert( is_not_dead(n3), "can not use dead node");
 460   assert( is_not_dead(n4), "can not use dead node");
 461   assert( is_not_dead(n5), "can not use dead node");
 462   assert( is_not_dead(n6), "can not use dead node");
 463   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 464   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 465   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 466   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 467   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 468   _in[5] = n5; if (n5 != nullptr) n5->add_out((Node *)this);
 469   _in[6] = n6; if (n6 != nullptr) n6->add_out((Node *)this);
 470 }
 471 
 472 #ifdef __clang__
 473 #pragma clang diagnostic pop
 474 #endif
 475 
 476 
 477 //------------------------------clone------------------------------------------
 478 // Clone a Node.
 479 Node *Node::clone() const {
 480   Compile* C = Compile::current();
 481   uint s = size_of();           // Size of inherited Node
 482   Node *n = (Node*)C->node_arena()->AmallocWords(size_of() + _max*sizeof(Node*));
 483   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 484   // Set the new input pointer array
 485   n->_in = (Node**)(((char*)n)+s);
 486   // Cannot share the old output pointer array, so kill it
 487   n->_out = NO_OUT_ARRAY;
 488   // And reset the counters to 0
 489   n->_outcnt = 0;
 490   n->_outmax = 0;
 491   // Unlock this guy, since he is not in any hash table.
 492   debug_only(n->_hash_lock = 0);
 493   // Walk the old node's input list to duplicate its edges
 494   uint i;
 495   for( i = 0; i < len(); i++ ) {
 496     Node *x = in(i);
 497     n->_in[i] = x;
 498     if (x != nullptr) x->add_out(n);
 499   }
 500   if (is_macro()) {
 501     C->add_macro_node(n);
 502   }
 503   if (is_expensive()) {
 504     C->add_expensive_node(n);
 505   }
 506   if (for_post_loop_opts_igvn()) {
 507     // Don't add cloned node to Compile::_for_post_loop_opts_igvn list automatically.
 508     // If it is applicable, it will happen anyway when the cloned node is registered with IGVN.
 509     n->remove_flag(Node::NodeFlags::Flag_for_post_loop_opts_igvn);
 510   }
 511   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 512   bs->register_potential_barrier_node(n);
 513 
 514   n->set_idx(C->next_unique()); // Get new unique index as well
 515   NOT_PRODUCT(n->_igv_idx = C->next_igv_idx());
 516   debug_only( n->verify_construction() );
 517   NOT_PRODUCT(nodes_created++);
 518   // Do not patch over the debug_idx of a clone, because it makes it
 519   // impossible to break on the clone's moment of creation.
 520   //debug_only( n->set_debug_idx( debug_idx() ) );
 521 
 522   C->copy_node_notes_to(n, (Node*) this);
 523 
 524   // MachNode clone
 525   uint nopnds;
 526   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 527     MachNode *mach  = n->as_Mach();
 528     MachNode *mthis = this->as_Mach();
 529     // Get address of _opnd_array.
 530     // It should be the same offset since it is the clone of this node.
 531     MachOper **from = mthis->_opnds;
 532     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 533                     pointer_delta((const void*)from,
 534                                   (const void*)(&mthis->_opnds), 1));
 535     mach->_opnds = to;
 536     for ( uint i = 0; i < nopnds; ++i ) {
 537       to[i] = from[i]->clone();
 538     }
 539   }
 540   if (n->is_Call()) {
 541     // CallGenerator is linked to the original node.
 542     CallGenerator* cg = n->as_Call()->generator();
 543     if (cg != nullptr) {
 544       CallGenerator* cloned_cg = cg->with_call_node(n->as_Call());
 545       n->as_Call()->set_generator(cloned_cg);
 546 
 547       C->print_inlining_assert_ready();
 548       C->print_inlining_move_to(cg);
 549       C->print_inlining_update(cloned_cg);
 550     }
 551   }
 552   if (n->is_SafePoint()) {
 553     // Scalar replacement and macro expansion might modify the JVMState.
 554     // Clone it to make sure it's not shared between SafePointNodes.
 555     n->as_SafePoint()->clone_jvms(C);
 556     n->as_SafePoint()->clone_replaced_nodes();
 557   }
 558   Compile::current()->record_modified_node(n);
 559   return n;                     // Return the clone
 560 }
 561 
 562 //---------------------------setup_is_top--------------------------------------
 563 // Call this when changing the top node, to reassert the invariants
 564 // required by Node::is_top.  See Compile::set_cached_top_node.
 565 void Node::setup_is_top() {
 566   if (this == (Node*)Compile::current()->top()) {
 567     // This node has just become top.  Kill its out array.
 568     _outcnt = _outmax = 0;
 569     _out = nullptr;                           // marker value for top
 570     assert(is_top(), "must be top");
 571   } else {
 572     if (_out == nullptr)  _out = NO_OUT_ARRAY;
 573     assert(!is_top(), "must not be top");
 574   }
 575 }
 576 
 577 //------------------------------~Node------------------------------------------
 578 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 579 void Node::destruct(PhaseValues* phase) {
 580   Compile* compile = (phase != nullptr) ? phase->C : Compile::current();
 581   if (phase != nullptr && phase->is_IterGVN()) {
 582     phase->is_IterGVN()->_worklist.remove(this);
 583   }
 584   // If this is the most recently created node, reclaim its index. Otherwise,
 585   // record the node as dead to keep liveness information accurate.
 586   if ((uint)_idx+1 == compile->unique()) {
 587     compile->set_unique(compile->unique()-1);
 588   } else {
 589     compile->record_dead_node(_idx);
 590   }
 591   // Clear debug info:
 592   Node_Notes* nn = compile->node_notes_at(_idx);
 593   if (nn != nullptr)  nn->clear();
 594   // Walk the input array, freeing the corresponding output edges
 595   _cnt = _max;  // forget req/prec distinction
 596   uint i;
 597   for( i = 0; i < _max; i++ ) {
 598     set_req(i, nullptr);
 599     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 600   }
 601   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 602 
 603   if (is_macro()) {
 604     compile->remove_macro_node(this);
 605   }
 606   if (is_expensive()) {
 607     compile->remove_expensive_node(this);
 608   }
 609   if (Opcode() == Op_Opaque4) {
 610     compile->remove_template_assertion_predicate_opaq(this);
 611   }
 612   if (for_post_loop_opts_igvn()) {
 613     compile->remove_from_post_loop_opts_igvn(this);
 614   }
 615 
 616   if (is_SafePoint()) {
 617     as_SafePoint()->delete_replaced_nodes();
 618 
 619     if (is_CallStaticJava()) {
 620       compile->remove_unstable_if_trap(as_CallStaticJava(), false);
 621     }
 622   }
 623   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 624   bs->unregister_potential_barrier_node(this);
 625 
 626   // See if the input array was allocated just prior to the object
 627   int edge_size = _max*sizeof(void*);
 628   int out_edge_size = _outmax*sizeof(void*);
 629   char *in_array = ((char*)_in);
 630   char *edge_end = in_array + edge_size;
 631   char *out_array = (char*)(_out == NO_OUT_ARRAY? nullptr: _out);
 632   int node_size = size_of();
 633 
 634 #ifdef ASSERT
 635   // We will not actually delete the storage, but we'll make the node unusable.
 636   compile->remove_modified_node(this);
 637   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 638   _in = _out = (Node**) badAddress;
 639   _max = _cnt = _outmax = _outcnt = 0;
 640 #endif
 641 
 642   // Free the output edge array
 643   if (out_edge_size > 0) {
 644     compile->node_arena()->Afree(out_array, out_edge_size);
 645   }
 646 
 647   // Free the input edge array and the node itself
 648   if( edge_end == (char*)this ) {
 649     // It was; free the input array and object all in one hit
 650 #ifndef ASSERT
 651     compile->node_arena()->Afree(in_array, edge_size+node_size);
 652 #endif
 653   } else {
 654     // Free just the input array
 655     compile->node_arena()->Afree(in_array, edge_size);
 656 
 657     // Free just the object
 658 #ifndef ASSERT
 659     compile->node_arena()->Afree(this, node_size);
 660 #endif
 661   }
 662 }
 663 
 664 //------------------------------grow-------------------------------------------
 665 // Grow the input array, making space for more edges
 666 void Node::grow(uint len) {
 667   Arena* arena = Compile::current()->node_arena();
 668   uint new_max = _max;
 669   if( new_max == 0 ) {
 670     _max = 4;
 671     _in = (Node**)arena->Amalloc(4*sizeof(Node*));
 672     Node** to = _in;
 673     to[0] = nullptr;
 674     to[1] = nullptr;
 675     to[2] = nullptr;
 676     to[3] = nullptr;
 677     return;
 678   }
 679   new_max = next_power_of_2(len);
 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   _in = (Node**)arena->Arealloc(_in, _max*sizeof(Node*), new_max*sizeof(Node*));
 684   Copy::zero_to_bytes(&_in[_max], (new_max-_max)*sizeof(Node*)); // null all new space
 685   _max = new_max;               // Record new max length
 686   // This assertion makes sure that Node::_max is wide enough to
 687   // represent the numerical value of new_max.
 688   assert(_max == new_max && _max > len, "int width of _max is too small");
 689 }
 690 
 691 //-----------------------------out_grow----------------------------------------
 692 // Grow the input array, making space for more edges
 693 void Node::out_grow( uint len ) {
 694   assert(!is_top(), "cannot grow a top node's out array");
 695   Arena* arena = Compile::current()->node_arena();
 696   uint new_max = _outmax;
 697   if( new_max == 0 ) {
 698     _outmax = 4;
 699     _out = (Node **)arena->Amalloc(4*sizeof(Node*));
 700     return;
 701   }
 702   new_max = next_power_of_2(len);
 703   // Trimming to limit allows a uint8 to handle up to 255 edges.
 704   // Previously I was using only powers-of-2 which peaked at 128 edges.
 705   //if( new_max >= limit ) new_max = limit-1;
 706   assert(_out != nullptr && _out != NO_OUT_ARRAY, "out must have sensible value");
 707   _out = (Node**)arena->Arealloc(_out,_outmax*sizeof(Node*),new_max*sizeof(Node*));
 708   //Copy::zero_to_bytes(&_out[_outmax], (new_max-_outmax)*sizeof(Node*)); // null all new space
 709   _outmax = new_max;               // Record new max length
 710   // This assertion makes sure that Node::_max is wide enough to
 711   // represent the numerical value of new_max.
 712   assert(_outmax == new_max && _outmax > len, "int width of _outmax is too small");
 713 }
 714 
 715 #ifdef ASSERT
 716 //------------------------------is_dead----------------------------------------
 717 bool Node::is_dead() const {
 718   // Mach and pinch point nodes may look like dead.
 719   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 720     return false;
 721   for( uint i = 0; i < _max; i++ )
 722     if( _in[i] != nullptr )
 723       return false;
 724   return true;
 725 }
 726 
 727 bool Node::is_not_dead(const Node* n) {
 728   return n == nullptr || !PhaseIterGVN::is_verify_def_use() || !(n->is_dead());
 729 }
 730 
 731 bool Node::is_reachable_from_root() const {
 732   ResourceMark rm;
 733   Unique_Node_List wq;
 734   wq.push((Node*)this);
 735   RootNode* root = Compile::current()->root();
 736   for (uint i = 0; i < wq.size(); i++) {
 737     Node* m = wq.at(i);
 738     if (m == root) {
 739       return true;
 740     }
 741     for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
 742       Node* u = m->fast_out(j);
 743       wq.push(u);
 744     }
 745   }
 746   return false;
 747 }
 748 #endif
 749 
 750 //------------------------------is_unreachable---------------------------------
 751 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 752   assert(!is_Mach(), "doesn't work with MachNodes");
 753   return outcnt() == 0 || igvn.type(this) == Type::TOP || (in(0) != nullptr && in(0)->is_top());
 754 }
 755 
 756 //------------------------------add_req----------------------------------------
 757 // Add a new required input at the end
 758 void Node::add_req( Node *n ) {
 759   assert( is_not_dead(n), "can not use dead node");
 760 
 761   // Look to see if I can move precedence down one without reallocating
 762   if( (_cnt >= _max) || (in(_max-1) != nullptr) )
 763     grow( _max+1 );
 764 
 765   // Find a precedence edge to move
 766   if( in(_cnt) != nullptr ) {   // Next precedence edge is busy?
 767     uint i;
 768     for( i=_cnt; i<_max; i++ )
 769       if( in(i) == nullptr )    // Find the null at end of prec edge list
 770         break;                  // There must be one, since we grew the array
 771     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 772   }
 773   _in[_cnt++] = n;            // Stuff over old prec edge
 774   if (n != nullptr) n->add_out((Node *)this);
 775   Compile::current()->record_modified_node(this);
 776 }
 777 
 778 //---------------------------add_req_batch-------------------------------------
 779 // Add a new required input at the end
 780 void Node::add_req_batch( Node *n, uint m ) {
 781   assert( is_not_dead(n), "can not use dead node");
 782   // check various edge cases
 783   if ((int)m <= 1) {
 784     assert((int)m >= 0, "oob");
 785     if (m != 0)  add_req(n);
 786     return;
 787   }
 788 
 789   // Look to see if I can move precedence down one without reallocating
 790   if( (_cnt+m) > _max || _in[_max-m] )
 791     grow( _max+m );
 792 
 793   // Find a precedence edge to move
 794   if( _in[_cnt] != nullptr ) {  // Next precedence edge is busy?
 795     uint i;
 796     for( i=_cnt; i<_max; i++ )
 797       if( _in[i] == nullptr )   // Find the null at end of prec edge list
 798         break;                  // There must be one, since we grew the array
 799     // Slide all the precs over by m positions (assume #prec << m).
 800     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 801   }
 802 
 803   // Stuff over the old prec edges
 804   for(uint i=0; i<m; i++ ) {
 805     _in[_cnt++] = n;
 806   }
 807 
 808   // Insert multiple out edges on the node.
 809   if (n != nullptr && !n->is_top()) {
 810     for(uint i=0; i<m; i++ ) {
 811       n->add_out((Node *)this);
 812     }
 813   }
 814   Compile::current()->record_modified_node(this);
 815 }
 816 
 817 //------------------------------del_req----------------------------------------
 818 // Delete the required edge and compact the edge array
 819 void Node::del_req( uint idx ) {
 820   assert( idx < _cnt, "oob");
 821   assert( !VerifyHashTableKeys || _hash_lock == 0,
 822           "remove node from hash table before modifying it");
 823   // First remove corresponding def-use edge
 824   Node *n = in(idx);
 825   if (n != nullptr) n->del_out((Node *)this);
 826   _in[idx] = in(--_cnt); // Compact the array
 827   // Avoid spec violation: Gap in prec edges.
 828   close_prec_gap_at(_cnt);
 829   Compile::current()->record_modified_node(this);
 830 }
 831 
 832 //------------------------------del_req_ordered--------------------------------
 833 // Delete the required edge and compact the edge array with preserved order
 834 void Node::del_req_ordered( uint idx ) {
 835   assert( idx < _cnt, "oob");
 836   assert( !VerifyHashTableKeys || _hash_lock == 0,
 837           "remove node from hash table before modifying it");
 838   // First remove corresponding def-use edge
 839   Node *n = in(idx);
 840   if (n != nullptr) n->del_out((Node *)this);
 841   if (idx < --_cnt) {    // Not last edge ?
 842     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
 843   }
 844   // Avoid spec violation: Gap in prec edges.
 845   close_prec_gap_at(_cnt);
 846   Compile::current()->record_modified_node(this);
 847 }
 848 
 849 //------------------------------ins_req----------------------------------------
 850 // Insert a new required input at the end
 851 void Node::ins_req( uint idx, Node *n ) {
 852   assert( is_not_dead(n), "can not use dead node");
 853   add_req(nullptr);                // Make space
 854   assert( idx < _max, "Must have allocated enough space");
 855   // Slide over
 856   if(_cnt-idx-1 > 0) {
 857     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 858   }
 859   _in[idx] = n;                            // Stuff over old required edge
 860   if (n != nullptr) n->add_out((Node *)this); // Add reciprocal def-use edge
 861   Compile::current()->record_modified_node(this);
 862 }
 863 
 864 //-----------------------------find_edge---------------------------------------
 865 int Node::find_edge(Node* n) {
 866   for (uint i = 0; i < len(); i++) {
 867     if (_in[i] == n)  return i;
 868   }
 869   return -1;
 870 }
 871 
 872 //----------------------------replace_edge-------------------------------------
 873 int Node::replace_edge(Node* old, Node* neww, PhaseGVN* gvn) {
 874   if (old == neww)  return 0;  // nothing to do
 875   uint nrep = 0;
 876   for (uint i = 0; i < len(); i++) {
 877     if (in(i) == old) {
 878       if (i < req()) {
 879         if (gvn != nullptr) {
 880           set_req_X(i, neww, gvn);
 881         } else {
 882           set_req(i, neww);
 883         }
 884       } else {
 885         assert(gvn == nullptr || gvn->is_IterGVN() == nullptr, "no support for igvn here");
 886         assert(find_prec_edge(neww) == -1, "spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx);
 887         set_prec(i, neww);
 888       }
 889       nrep++;
 890     }
 891   }
 892   return nrep;
 893 }
 894 
 895 /**
 896  * Replace input edges in the range pointing to 'old' node.
 897  */
 898 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end, PhaseGVN* gvn) {
 899   if (old == neww)  return 0;  // nothing to do
 900   uint nrep = 0;
 901   for (int i = start; i < end; i++) {
 902     if (in(i) == old) {
 903       set_req_X(i, neww, gvn);
 904       nrep++;
 905     }
 906   }
 907   return nrep;
 908 }
 909 
 910 //-------------------------disconnect_inputs-----------------------------------
 911 // null out all inputs to eliminate incoming Def-Use edges.
 912 void Node::disconnect_inputs(Compile* C) {
 913   // the layout of Node::_in
 914   // r: a required input, null is allowed
 915   // p: a precedence, null values are all at the end
 916   // -----------------------------------
 917   // |r|...|r|p|...|p|null|...|null|
 918   //         |                     |
 919   //         req()                 len()
 920   // -----------------------------------
 921   for (uint i = 0; i < req(); ++i) {
 922     if (in(i) != nullptr) {
 923       set_req(i, nullptr);
 924     }
 925   }
 926 
 927   // Remove precedence edges if any exist
 928   // Note: Safepoints may have precedence edges, even during parsing
 929   for (uint i = len(); i > req(); ) {
 930     rm_prec(--i);  // no-op if _in[i] is null
 931   }
 932 
 933 #ifdef ASSERT
 934   // sanity check
 935   for (uint i = 0; i < len(); ++i) {
 936     assert(_in[i] == nullptr, "disconnect_inputs() failed!");
 937   }
 938 #endif
 939 
 940   // Node::destruct requires all out edges be deleted first
 941   // debug_only(destruct();)   // no reuse benefit expected
 942   C->record_dead_node(_idx);
 943 }
 944 
 945 //-----------------------------uncast---------------------------------------
 946 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 947 // Strip away casting.  (It is depth-limited.)
 948 // Optionally, keep casts with dependencies.
 949 Node* Node::uncast(bool keep_deps) const {
 950   // Should be inline:
 951   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 952   if (is_ConstraintCast()) {
 953     return uncast_helper(this, keep_deps);
 954   } else {
 955     return (Node*) this;
 956   }
 957 }
 958 
 959 // Find out of current node that matches opcode.
 960 Node* Node::find_out_with(int opcode) {
 961   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 962     Node* use = fast_out(i);
 963     if (use->Opcode() == opcode) {
 964       return use;
 965     }
 966   }
 967   return nullptr;
 968 }
 969 
 970 // Return true if the current node has an out that matches opcode.
 971 bool Node::has_out_with(int opcode) {
 972   return (find_out_with(opcode) != nullptr);
 973 }
 974 
 975 // Return true if the current node has an out that matches any of the opcodes.
 976 bool Node::has_out_with(int opcode1, int opcode2, int opcode3, int opcode4) {
 977   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 978       int opcode = fast_out(i)->Opcode();
 979       if (opcode == opcode1 || opcode == opcode2 || opcode == opcode3 || opcode == opcode4) {
 980         return true;
 981       }
 982   }
 983   return false;
 984 }
 985 
 986 
 987 //---------------------------uncast_helper-------------------------------------
 988 Node* Node::uncast_helper(const Node* p, bool keep_deps) {
 989 #ifdef ASSERT
 990   uint depth_count = 0;
 991   const Node* orig_p = p;
 992 #endif
 993 
 994   while (true) {
 995 #ifdef ASSERT
 996     if (depth_count >= K) {
 997       orig_p->dump(4);
 998       if (p != orig_p)
 999         p->dump(1);
1000     }
1001     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
1002 #endif
1003     if (p == nullptr || p->req() != 2) {
1004       break;
1005     } else if (p->is_ConstraintCast()) {
1006       if (keep_deps && p->as_ConstraintCast()->carry_dependency()) {
1007         break; // stop at casts with dependencies
1008       }
1009       p = p->in(1);
1010     } else {
1011       break;
1012     }
1013   }
1014   return (Node*) p;
1015 }
1016 
1017 //------------------------------add_prec---------------------------------------
1018 // Add a new precedence input.  Precedence inputs are unordered, with
1019 // duplicates removed and nulls packed down at the end.
1020 void Node::add_prec( Node *n ) {
1021   assert( is_not_dead(n), "can not use dead node");
1022 
1023   // Check for null at end
1024   if( _cnt >= _max || in(_max-1) )
1025     grow( _max+1 );
1026 
1027   // Find a precedence edge to move
1028   uint i = _cnt;
1029   while( in(i) != nullptr ) {
1030     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
1031     i++;
1032   }
1033   _in[i] = n;                                   // Stuff prec edge over null
1034   if ( n != nullptr) n->add_out((Node *)this);  // Add mirror edge
1035 
1036 #ifdef ASSERT
1037   while ((++i)<_max) { assert(_in[i] == nullptr, "spec violation: Gap in prec edges (node %d)", _idx); }
1038 #endif
1039   Compile::current()->record_modified_node(this);
1040 }
1041 
1042 //------------------------------rm_prec----------------------------------------
1043 // Remove a precedence input.  Precedence inputs are unordered, with
1044 // duplicates removed and nulls packed down at the end.
1045 void Node::rm_prec( uint j ) {
1046   assert(j < _max, "oob: i=%d, _max=%d", j, _max);
1047   assert(j >= _cnt, "not a precedence edge");
1048   if (_in[j] == nullptr) return;   // Avoid spec violation: Gap in prec edges.
1049   _in[j]->del_out((Node *)this);
1050   close_prec_gap_at(j);
1051   Compile::current()->record_modified_node(this);
1052 }
1053 
1054 //------------------------------size_of----------------------------------------
1055 uint Node::size_of() const { return sizeof(*this); }
1056 
1057 //------------------------------ideal_reg--------------------------------------
1058 uint Node::ideal_reg() const { return 0; }
1059 
1060 //------------------------------jvms-------------------------------------------
1061 JVMState* Node::jvms() const { return nullptr; }
1062 
1063 #ifdef ASSERT
1064 //------------------------------jvms-------------------------------------------
1065 bool Node::verify_jvms(const JVMState* using_jvms) const {
1066   for (JVMState* jvms = this->jvms(); jvms != nullptr; jvms = jvms->caller()) {
1067     if (jvms == using_jvms)  return true;
1068   }
1069   return false;
1070 }
1071 
1072 //------------------------------init_NodeProperty------------------------------
1073 void Node::init_NodeProperty() {
1074   assert(_max_classes <= max_juint, "too many NodeProperty classes");
1075   assert(max_flags() <= max_juint, "too many NodeProperty flags");
1076 }
1077 
1078 //-----------------------------max_flags---------------------------------------
1079 juint Node::max_flags() {
1080   return (PD::_last_flag << 1) - 1; // allow flags combination
1081 }
1082 #endif
1083 
1084 //------------------------------format-----------------------------------------
1085 // Print as assembly
1086 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1087 //------------------------------emit-------------------------------------------
1088 // Emit bytes starting at parameter 'ptr'.
1089 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
1090 //------------------------------size-------------------------------------------
1091 // Size of instruction in bytes
1092 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1093 
1094 //------------------------------CFG Construction-------------------------------
1095 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1096 // Goto and Return.
1097 const Node *Node::is_block_proj() const { return 0; }
1098 
1099 // Minimum guaranteed type
1100 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1101 
1102 
1103 //------------------------------raise_bottom_type------------------------------
1104 // Get the worst-case Type output for this Node.
1105 void Node::raise_bottom_type(const Type* new_type) {
1106   if (is_Type()) {
1107     TypeNode *n = this->as_Type();
1108     if (VerifyAliases) {
1109       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1110     }
1111     n->set_type(new_type);
1112   } else if (is_Load()) {
1113     LoadNode *n = this->as_Load();
1114     if (VerifyAliases) {
1115       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1116     }
1117     n->set_type(new_type);
1118   }
1119 }
1120 
1121 //------------------------------Identity---------------------------------------
1122 // Return a node that the given node is equivalent to.
1123 Node* Node::Identity(PhaseGVN* phase) {
1124   return this;                  // Default to no identities
1125 }
1126 
1127 //------------------------------Value------------------------------------------
1128 // Compute a new Type for a node using the Type of the inputs.
1129 const Type* Node::Value(PhaseGVN* phase) const {
1130   return bottom_type();         // Default to worst-case Type
1131 }
1132 
1133 //------------------------------Ideal------------------------------------------
1134 //
1135 // 'Idealize' the graph rooted at this Node.
1136 //
1137 // In order to be efficient and flexible there are some subtle invariants
1138 // these Ideal calls need to hold.  Running with '-XX:VerifyIterativeGVN=1' checks
1139 // these invariants, although its too slow to have on by default.  If you are
1140 // hacking an Ideal call, be sure to test with '-XX:VerifyIterativeGVN=1'
1141 //
1142 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1143 // pointer.  If ANY change is made, it must return the root of the reshaped
1144 // graph - even if the root is the same Node.  Example: swapping the inputs
1145 // to an AddINode gives the same answer and same root, but you still have to
1146 // return the 'this' pointer instead of null.
1147 //
1148 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1149 // Identity call to return an old Node; basically if Identity can find
1150 // another Node have the Ideal call make no change and return null.
1151 // Example: AddINode::Ideal must check for add of zero; in this case it
1152 // returns null instead of doing any graph reshaping.
1153 //
1154 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1155 // sharing there may be other users of the old Nodes relying on their current
1156 // semantics.  Modifying them will break the other users.
1157 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1158 // "X+3" unchanged in case it is shared.
1159 //
1160 // If you modify the 'this' pointer's inputs, you should use
1161 // 'set_req'.  If you are making a new Node (either as the new root or
1162 // some new internal piece) you may use 'init_req' to set the initial
1163 // value.  You can make a new Node with either 'new' or 'clone'.  In
1164 // either case, def-use info is correctly maintained.
1165 //
1166 // Example: reshape "(X+3)+4" into "X+7":
1167 //    set_req(1, in(1)->in(1));
1168 //    set_req(2, phase->intcon(7));
1169 //    return this;
1170 // Example: reshape "X*4" into "X<<2"
1171 //    return new LShiftINode(in(1), phase->intcon(2));
1172 //
1173 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1174 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1175 //    Node *shift=phase->transform(new LShiftINode(in(1),phase->intcon(5)));
1176 //    return new AddINode(shift, in(1));
1177 //
1178 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1179 // These forms are faster than 'phase->transform(new ConNode())' and Do
1180 // The Right Thing with def-use info.
1181 //
1182 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1183 // graph uses the 'this' Node it must be the root.  If you want a Node with
1184 // the same Opcode as the 'this' pointer use 'clone'.
1185 //
1186 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1187   return nullptr;                  // Default to being Ideal already
1188 }
1189 
1190 // Some nodes have specific Ideal subgraph transformations only if they are
1191 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1192 // for the transformations to happen.
1193 bool Node::has_special_unique_user() const {
1194   assert(outcnt() == 1, "match only for unique out");
1195   Node* n = unique_out();
1196   int op  = Opcode();
1197   if (this->is_Store()) {
1198     // Condition for back-to-back stores folding.
1199     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1200   } else if (this->is_Load() || this->is_DecodeN() || this->is_Phi()) {
1201     // Condition for removing an unused LoadNode or DecodeNNode from the MemBarAcquire precedence input
1202     return n->Opcode() == Op_MemBarAcquire;
1203   } else if (op == Op_AddL) {
1204     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1205     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1206   } else if (op == Op_SubI || op == Op_SubL) {
1207     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1208     return n->Opcode() == op && n->in(2) == this;
1209   } else if (is_If() && (n->is_IfFalse() || n->is_IfTrue())) {
1210     // See IfProjNode::Identity()
1211     return true;
1212   } else if ((is_IfFalse() || is_IfTrue()) && n->is_If()) {
1213     // See IfNode::fold_compares
1214     return true;
1215   } else {
1216     return false;
1217   }
1218 };
1219 
1220 //--------------------------find_exact_control---------------------------------
1221 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1222 Node* Node::find_exact_control(Node* ctrl) {
1223   if (ctrl == nullptr && this->is_Region())
1224     ctrl = this->as_Region()->is_copy();
1225 
1226   if (ctrl != nullptr && ctrl->is_CatchProj()) {
1227     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1228       ctrl = ctrl->in(0);
1229     if (ctrl != nullptr && !ctrl->is_top())
1230       ctrl = ctrl->in(0);
1231   }
1232 
1233   if (ctrl != nullptr && ctrl->is_Proj())
1234     ctrl = ctrl->in(0);
1235 
1236   return ctrl;
1237 }
1238 
1239 //--------------------------dominates------------------------------------------
1240 // Helper function for MemNode::all_controls_dominate().
1241 // Check if 'this' control node dominates or equal to 'sub' control node.
1242 // We already know that if any path back to Root or Start reaches 'this',
1243 // then all paths so, so this is a simple search for one example,
1244 // not an exhaustive search for a counterexample.
1245 bool Node::dominates(Node* sub, Node_List &nlist) {
1246   assert(this->is_CFG(), "expecting control");
1247   assert(sub != nullptr && sub->is_CFG(), "expecting control");
1248 
1249   // detect dead cycle without regions
1250   int iterations_without_region_limit = DominatorSearchLimit;
1251 
1252   Node* orig_sub = sub;
1253   Node* dom      = this;
1254   bool  met_dom  = false;
1255   nlist.clear();
1256 
1257   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1258   // After seeing 'dom', continue up to Root or Start.
1259   // If we hit a region (backward split point), it may be a loop head.
1260   // Keep going through one of the region's inputs.  If we reach the
1261   // same region again, go through a different input.  Eventually we
1262   // will either exit through the loop head, or give up.
1263   // (If we get confused, break out and return a conservative 'false'.)
1264   while (sub != nullptr) {
1265     if (sub->is_top())  break; // Conservative answer for dead code.
1266     if (sub == dom) {
1267       if (nlist.size() == 0) {
1268         // No Region nodes except loops were visited before and the EntryControl
1269         // path was taken for loops: it did not walk in a cycle.
1270         return true;
1271       } else if (met_dom) {
1272         break;          // already met before: walk in a cycle
1273       } else {
1274         // Region nodes were visited. Continue walk up to Start or Root
1275         // to make sure that it did not walk in a cycle.
1276         met_dom = true; // first time meet
1277         iterations_without_region_limit = DominatorSearchLimit; // Reset
1278      }
1279     }
1280     if (sub->is_Start() || sub->is_Root()) {
1281       // Success if we met 'dom' along a path to Start or Root.
1282       // We assume there are no alternative paths that avoid 'dom'.
1283       // (This assumption is up to the caller to ensure!)
1284       return met_dom;
1285     }
1286     Node* up = sub->in(0);
1287     // Normalize simple pass-through regions and projections:
1288     up = sub->find_exact_control(up);
1289     // If sub == up, we found a self-loop.  Try to push past it.
1290     if (sub == up && sub->is_Loop()) {
1291       // Take loop entry path on the way up to 'dom'.
1292       up = sub->in(1); // in(LoopNode::EntryControl);
1293     } else if (sub == up && sub->is_Region() && sub->req() == 2) {
1294       // Take in(1) path on the way up to 'dom' for regions with only one input
1295       up = sub->in(1);
1296     } else if (sub == up && sub->is_Region()) {
1297       // Try both paths for Regions with 2 input paths (it may be a loop head).
1298       // It could give conservative 'false' answer without information
1299       // which region's input is the entry path.
1300       iterations_without_region_limit = DominatorSearchLimit; // Reset
1301 
1302       bool region_was_visited_before = false;
1303       // Was this Region node visited before?
1304       // If so, we have reached it because we accidentally took a
1305       // loop-back edge from 'sub' back into the body of the loop,
1306       // and worked our way up again to the loop header 'sub'.
1307       // So, take the first unexplored path on the way up to 'dom'.
1308       for (int j = nlist.size() - 1; j >= 0; j--) {
1309         intptr_t ni = (intptr_t)nlist.at(j);
1310         Node* visited = (Node*)(ni & ~1);
1311         bool  visited_twice_already = ((ni & 1) != 0);
1312         if (visited == sub) {
1313           if (visited_twice_already) {
1314             // Visited 2 paths, but still stuck in loop body.  Give up.
1315             return false;
1316           }
1317           // The Region node was visited before only once.
1318           // (We will repush with the low bit set, below.)
1319           nlist.remove(j);
1320           // We will find a new edge and re-insert.
1321           region_was_visited_before = true;
1322           break;
1323         }
1324       }
1325 
1326       // Find an incoming edge which has not been seen yet; walk through it.
1327       assert(up == sub, "");
1328       uint skip = region_was_visited_before ? 1 : 0;
1329       for (uint i = 1; i < sub->req(); i++) {
1330         Node* in = sub->in(i);
1331         if (in != nullptr && !in->is_top() && in != sub) {
1332           if (skip == 0) {
1333             up = in;
1334             break;
1335           }
1336           --skip;               // skip this nontrivial input
1337         }
1338       }
1339 
1340       // Set 0 bit to indicate that both paths were taken.
1341       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1342     }
1343 
1344     if (up == sub) {
1345       break;    // some kind of tight cycle
1346     }
1347     if (up == orig_sub && met_dom) {
1348       // returned back after visiting 'dom'
1349       break;    // some kind of cycle
1350     }
1351     if (--iterations_without_region_limit < 0) {
1352       break;    // dead cycle
1353     }
1354     sub = up;
1355   }
1356 
1357   // Did not meet Root or Start node in pred. chain.
1358   // Conservative answer for dead code.
1359   return false;
1360 }
1361 
1362 //------------------------------remove_dead_region-----------------------------
1363 // This control node is dead.  Follow the subgraph below it making everything
1364 // using it dead as well.  This will happen normally via the usual IterGVN
1365 // worklist but this call is more efficient.  Do not update use-def info
1366 // inside the dead region, just at the borders.
1367 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1368   // Con's are a popular node to re-hit in the hash table again.
1369   if( dead->is_Con() ) return;
1370 
1371   ResourceMark rm;
1372   Node_List nstack;
1373   VectorSet dead_set; // notify uses only once
1374 
1375   Node *top = igvn->C->top();
1376   nstack.push(dead);
1377   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1378 
1379   while (nstack.size() > 0) {
1380     dead = nstack.pop();
1381     if (!dead_set.test_set(dead->_idx)) {
1382       // If dead has any live uses, those are now still attached. Notify them before we lose them.
1383       igvn->add_users_to_worklist(dead);
1384     }
1385     if (dead->Opcode() == Op_SafePoint) {
1386       dead->as_SafePoint()->disconnect_from_root(igvn);
1387     }
1388     if (dead->outcnt() > 0) {
1389       // Keep dead node on stack until all uses are processed.
1390       nstack.push(dead);
1391       // For all Users of the Dead...    ;-)
1392       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1393         Node* use = dead->last_out(k);
1394         igvn->hash_delete(use);       // Yank from hash table prior to mod
1395         if (use->in(0) == dead) {     // Found another dead node
1396           assert (!use->is_Con(), "Control for Con node should be Root node.");
1397           use->set_req(0, top);       // Cut dead edge to prevent processing
1398           nstack.push(use);           // the dead node again.
1399         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1400                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1401                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1402           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1403           use->set_req(0, top);       // Cut self edge
1404           nstack.push(use);
1405         } else {                      // Else found a not-dead user
1406           // Dead if all inputs are top or null
1407           bool dead_use = !use->is_Root(); // Keep empty graph alive
1408           for (uint j = 1; j < use->req(); j++) {
1409             Node* in = use->in(j);
1410             if (in == dead) {         // Turn all dead inputs into TOP
1411               use->set_req(j, top);
1412             } else if (in != nullptr && !in->is_top()) {
1413               dead_use = false;
1414             }
1415           }
1416           if (dead_use) {
1417             if (use->is_Region()) {
1418               use->set_req(0, top);   // Cut self edge
1419             }
1420             nstack.push(use);
1421           } else {
1422             igvn->_worklist.push(use);
1423           }
1424         }
1425         // Refresh the iterator, since any number of kills might have happened.
1426         k = dead->last_outs(kmin);
1427       }
1428     } else { // (dead->outcnt() == 0)
1429       // Done with outputs.
1430       igvn->hash_delete(dead);
1431       igvn->_worklist.remove(dead);
1432       igvn->set_type(dead, Type::TOP);
1433       // Kill all inputs to the dead guy
1434       for (uint i=0; i < dead->req(); i++) {
1435         Node *n = dead->in(i);      // Get input to dead guy
1436         if (n != nullptr && !n->is_top()) { // Input is valid?
1437           dead->set_req(i, top);    // Smash input away
1438           if (n->outcnt() == 0) {   // Input also goes dead?
1439             if (!n->is_Con())
1440               nstack.push(n);       // Clear it out as well
1441           } else if (n->outcnt() == 1 &&
1442                      n->has_special_unique_user()) {
1443             igvn->add_users_to_worklist( n );
1444           } else if (n->outcnt() <= 2 && n->is_Store()) {
1445             // Push store's uses on worklist to enable folding optimization for
1446             // store/store and store/load to the same address.
1447             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1448             // and remove_globally_dead_node().
1449             igvn->add_users_to_worklist( n );
1450           } else {
1451             BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, n);
1452           }
1453         }
1454       }
1455       igvn->C->remove_useless_node(dead);
1456     } // (dead->outcnt() == 0)
1457   }   // while (nstack.size() > 0) for outputs
1458   return;
1459 }
1460 
1461 //------------------------------remove_dead_region-----------------------------
1462 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1463   Node *n = in(0);
1464   if( !n ) return false;
1465   // Lost control into this guy?  I.e., it became unreachable?
1466   // Aggressively kill all unreachable code.
1467   if (can_reshape && n->is_top()) {
1468     kill_dead_code(this, phase->is_IterGVN());
1469     return false; // Node is dead.
1470   }
1471 
1472   if( n->is_Region() && n->as_Region()->is_copy() ) {
1473     Node *m = n->nonnull_req();
1474     set_req(0, m);
1475     return true;
1476   }
1477   return false;
1478 }
1479 
1480 //------------------------------hash-------------------------------------------
1481 // Hash function over Nodes.
1482 uint Node::hash() const {
1483   uint sum = 0;
1484   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1485     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded nulls
1486   return (sum>>2) + _cnt + Opcode();
1487 }
1488 
1489 //------------------------------cmp--------------------------------------------
1490 // Compare special parts of simple Nodes
1491 bool Node::cmp( const Node &n ) const {
1492   return true;                  // Must be same
1493 }
1494 
1495 //------------------------------rematerialize-----------------------------------
1496 // Should we clone rather than spill this instruction?
1497 bool Node::rematerialize() const {
1498   if ( is_Mach() )
1499     return this->as_Mach()->rematerialize();
1500   else
1501     return (_flags & Flag_rematerialize) != 0;
1502 }
1503 
1504 //------------------------------needs_anti_dependence_check---------------------
1505 // Nodes which use memory without consuming it, hence need antidependences.
1506 bool Node::needs_anti_dependence_check() const {
1507   if (req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0) {
1508     return false;
1509   }
1510   return in(1)->bottom_type()->has_memory();
1511 }
1512 
1513 // Get an integer constant from a ConNode (or CastIINode).
1514 // Return a default value if there is no apparent constant here.
1515 const TypeInt* Node::find_int_type() const {
1516   if (this->is_Type()) {
1517     return this->as_Type()->type()->isa_int();
1518   } else if (this->is_Con()) {
1519     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1520     return this->bottom_type()->isa_int();
1521   }
1522   return nullptr;
1523 }
1524 
1525 const TypeInteger* Node::find_integer_type(BasicType bt) const {
1526   if (this->is_Type()) {
1527     return this->as_Type()->type()->isa_integer(bt);
1528   } else if (this->is_Con()) {
1529     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1530     return this->bottom_type()->isa_integer(bt);
1531   }
1532   return nullptr;
1533 }
1534 
1535 // Get a pointer constant from a ConstNode.
1536 // Returns the constant if it is a pointer ConstNode
1537 intptr_t Node::get_ptr() const {
1538   assert( Opcode() == Op_ConP, "" );
1539   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1540 }
1541 
1542 // Get a narrow oop constant from a ConNNode.
1543 intptr_t Node::get_narrowcon() const {
1544   assert( Opcode() == Op_ConN, "" );
1545   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1546 }
1547 
1548 // Get a long constant from a ConNode.
1549 // Return a default value if there is no apparent constant here.
1550 const TypeLong* Node::find_long_type() const {
1551   if (this->is_Type()) {
1552     return this->as_Type()->type()->isa_long();
1553   } else if (this->is_Con()) {
1554     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1555     return this->bottom_type()->isa_long();
1556   }
1557   return nullptr;
1558 }
1559 
1560 
1561 /**
1562  * Return a ptr type for nodes which should have it.
1563  */
1564 const TypePtr* Node::get_ptr_type() const {
1565   const TypePtr* tp = this->bottom_type()->make_ptr();
1566 #ifdef ASSERT
1567   if (tp == nullptr) {
1568     this->dump(1);
1569     assert((tp != nullptr), "unexpected node type");
1570   }
1571 #endif
1572   return tp;
1573 }
1574 
1575 // Get a double constant from a ConstNode.
1576 // Returns the constant if it is a double ConstNode
1577 jdouble Node::getd() const {
1578   assert( Opcode() == Op_ConD, "" );
1579   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1580 }
1581 
1582 // Get a float constant from a ConstNode.
1583 // Returns the constant if it is a float ConstNode
1584 jfloat Node::getf() const {
1585   assert( Opcode() == Op_ConF, "" );
1586   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1587 }
1588 
1589 #ifndef PRODUCT
1590 
1591 // Call this from debugger:
1592 Node* old_root() {
1593   Matcher* matcher = Compile::current()->matcher();
1594   if (matcher != nullptr) {
1595     Node* new_root = Compile::current()->root();
1596     Node* old_root = matcher->find_old_node(new_root);
1597     if (old_root != nullptr) {
1598       return old_root;
1599     }
1600   }
1601   tty->print("old_root: not found.\n");
1602   return nullptr;
1603 }
1604 
1605 // BFS traverse all reachable nodes from start, call callback on them
1606 template <typename Callback>
1607 void visit_nodes(Node* start, Callback callback, bool traverse_output, bool only_ctrl) {
1608   Unique_Mixed_Node_List worklist;
1609   worklist.add(start);
1610   for (uint i = 0; i < worklist.size(); i++) {
1611     Node* n = worklist[i];
1612     callback(n);
1613     for (uint i = 0; i < n->len(); i++) {
1614       if (!only_ctrl || n->is_Region() || (n->Opcode() == Op_Root) || (i == TypeFunc::Control)) {
1615         // If only_ctrl is set: Add regions, the root node, or control inputs only
1616         worklist.add(n->in(i));
1617       }
1618     }
1619     if (traverse_output && !only_ctrl) {
1620       for (uint i = 0; i < n->outcnt(); i++) {
1621         worklist.add(n->raw_out(i));
1622       }
1623     }
1624   }
1625 }
1626 
1627 // BFS traverse from start, return node with idx
1628 Node* find_node_by_idx(Node* start, uint idx, bool traverse_output, bool only_ctrl) {
1629   ResourceMark rm;
1630   Node* result = nullptr;
1631   auto callback = [&] (Node* n) {
1632     if (n->_idx == idx) {
1633       if (result != nullptr) {
1634         tty->print("find_node_by_idx: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1635           (uintptr_t)result, (uintptr_t)n, idx);
1636       }
1637       result = n;
1638     }
1639   };
1640   visit_nodes(start, callback, traverse_output, only_ctrl);
1641   return result;
1642 }
1643 
1644 int node_idx_cmp(const Node** n1, const Node** n2) {
1645   return (*n1)->_idx - (*n2)->_idx;
1646 }
1647 
1648 void find_nodes_by_name(Node* start, const char* name) {
1649   ResourceMark rm;
1650   GrowableArray<const Node*> ns;
1651   auto callback = [&] (const Node* n) {
1652     if (StringUtils::is_star_match(name, n->Name())) {
1653       ns.push(n);
1654     }
1655   };
1656   visit_nodes(start, callback, true, false);
1657   ns.sort(node_idx_cmp);
1658   for (int i = 0; i < ns.length(); i++) {
1659     ns.at(i)->dump();
1660   }
1661 }
1662 
1663 void find_nodes_by_dump(Node* start, const char* pattern) {
1664   ResourceMark rm;
1665   GrowableArray<const Node*> ns;
1666   auto callback = [&] (const Node* n) {
1667     stringStream stream;
1668     n->dump("", false, &stream);
1669     if (StringUtils::is_star_match(pattern, stream.base())) {
1670       ns.push(n);
1671     }
1672   };
1673   visit_nodes(start, callback, true, false);
1674   ns.sort(node_idx_cmp);
1675   for (int i = 0; i < ns.length(); i++) {
1676     ns.at(i)->dump();
1677   }
1678 }
1679 
1680 // call from debugger: find node with name pattern in new/current graph
1681 // name can contain "*" in match pattern to match any characters
1682 // the matching is case insensitive
1683 void find_nodes_by_name(const char* name) {
1684   Node* root = Compile::current()->root();
1685   find_nodes_by_name(root, name);
1686 }
1687 
1688 // call from debugger: find node with name pattern in old graph
1689 // name can contain "*" in match pattern to match any characters
1690 // the matching is case insensitive
1691 void find_old_nodes_by_name(const char* name) {
1692   Node* root = old_root();
1693   find_nodes_by_name(root, name);
1694 }
1695 
1696 // call from debugger: find node with dump pattern in new/current graph
1697 // can contain "*" in match pattern to match any characters
1698 // the matching is case insensitive
1699 void find_nodes_by_dump(const char* pattern) {
1700   Node* root = Compile::current()->root();
1701   find_nodes_by_dump(root, pattern);
1702 }
1703 
1704 // call from debugger: find node with name pattern in old graph
1705 // can contain "*" in match pattern to match any characters
1706 // the matching is case insensitive
1707 void find_old_nodes_by_dump(const char* pattern) {
1708   Node* root = old_root();
1709   find_nodes_by_dump(root, pattern);
1710 }
1711 
1712 // Call this from debugger, search in same graph as n:
1713 Node* find_node(Node* n, const int idx) {
1714   return n->find(idx);
1715 }
1716 
1717 // Call this from debugger, search in new nodes:
1718 Node* find_node(const int idx) {
1719   return Compile::current()->root()->find(idx);
1720 }
1721 
1722 // Call this from debugger, search in old nodes:
1723 Node* find_old_node(const int idx) {
1724   Node* root = old_root();
1725   return (root == nullptr) ? nullptr : root->find(idx);
1726 }
1727 
1728 // Call this from debugger, search in same graph as n:
1729 Node* find_ctrl(Node* n, const int idx) {
1730   return n->find_ctrl(idx);
1731 }
1732 
1733 // Call this from debugger, search in new nodes:
1734 Node* find_ctrl(const int idx) {
1735   return Compile::current()->root()->find_ctrl(idx);
1736 }
1737 
1738 // Call this from debugger, search in old nodes:
1739 Node* find_old_ctrl(const int idx) {
1740   Node* root = old_root();
1741   return (root == nullptr) ? nullptr : root->find_ctrl(idx);
1742 }
1743 
1744 //------------------------------find_ctrl--------------------------------------
1745 // Find an ancestor to this node in the control history with given _idx
1746 Node* Node::find_ctrl(int idx) {
1747   return find(idx, true);
1748 }
1749 
1750 //------------------------------find-------------------------------------------
1751 // Tries to find the node with the index |idx| starting from this node. If idx is negative,
1752 // the search also includes forward (out) edges. Returns null if not found.
1753 // If only_ctrl is set, the search will only be done on control nodes. Returns null if
1754 // not found or if the node to be found is not a control node (search will not find it).
1755 Node* Node::find(const int idx, bool only_ctrl) {
1756   ResourceMark rm;
1757   return find_node_by_idx(this, abs(idx), (idx < 0), only_ctrl);
1758 }
1759 
1760 class PrintBFS {
1761 public:
1762   PrintBFS(const Node* start, const int max_distance, const Node* target, const char* options, outputStream* st)
1763   : _start(start), _max_distance(max_distance), _target(target), _options(options), _output(st),
1764     _dcc(this), _info_uid(cmpkey, hashkey) {}
1765 
1766   void run();
1767 private:
1768   // pipeline steps
1769   bool configure();
1770   void collect();
1771   void select();
1772   void select_all();
1773   void select_all_paths();
1774   void select_shortest_path();
1775   void sort();
1776   void print();
1777 
1778   // inputs
1779   const Node* _start;
1780   const int _max_distance;
1781   const Node* _target;
1782   const char* _options;
1783   outputStream* _output;
1784 
1785   // options
1786   bool _traverse_inputs = false;
1787   bool _traverse_outputs = false;
1788   struct Filter {
1789     bool _control = false;
1790     bool _memory = false;
1791     bool _data = false;
1792     bool _mixed = false;
1793     bool _other = false;
1794     bool is_empty() const {
1795       return !(_control || _memory || _data || _mixed || _other);
1796     }
1797     void set_all() {
1798       _control = true;
1799       _memory = true;
1800       _data = true;
1801       _mixed = true;
1802       _other = true;
1803     }
1804     // Check if the filter accepts the node. Go by the type categories, but also all CFG nodes
1805     // are considered to have control.
1806     bool accepts(const Node* n) {
1807       const Type* t = n->bottom_type();
1808       return ( _data    &&  t->has_category(Type::Category::Data)                    ) ||
1809              ( _memory  &&  t->has_category(Type::Category::Memory)                  ) ||
1810              ( _mixed   &&  t->has_category(Type::Category::Mixed)                   ) ||
1811              ( _control && (t->has_category(Type::Category::Control) || n->is_CFG()) ) ||
1812              ( _other   &&  t->has_category(Type::Category::Other)                   );
1813     }
1814   };
1815   Filter _filter_visit;
1816   Filter _filter_boundary;
1817   bool _sort_idx = false;
1818   bool _all_paths = false;
1819   bool _use_color = false;
1820   bool _print_blocks = false;
1821   bool _print_old = false;
1822   bool _dump_only = false;
1823   void print_options_help(bool print_examples);
1824   bool parse_options();
1825 
1826 public:
1827   class DumpConfigColored : public Node::DumpConfig {
1828   public:
1829     DumpConfigColored(PrintBFS* bfs) : _bfs(bfs) {};
1830     virtual void pre_dump(outputStream* st, const Node* n);
1831     virtual void post_dump(outputStream* st);
1832   private:
1833     PrintBFS* _bfs;
1834   };
1835 private:
1836   DumpConfigColored _dcc;
1837 
1838   // node info
1839   static Node* old_node(const Node* n); // mach node -> prior IR node
1840   void print_node_idx(const Node* n);
1841   void print_block_id(const Block* b);
1842   void print_node_block(const Node* n); // _pre_order, head idx, _idom, _dom_depth
1843 
1844   // traversal data structures
1845   GrowableArray<const Node*> _worklist; // BFS queue
1846   void maybe_traverse(const Node* src, const Node* dst);
1847 
1848   // node info annotation
1849   class Info {
1850   public:
1851     Info() : Info(nullptr, 0) {};
1852     Info(const Node* node, int distance)
1853       : _node(node), _distance_from_start(distance) {};
1854     const Node* node() const { return _node; };
1855     int distance() const { return _distance_from_start; };
1856     int distance_from_target() const { return _distance_from_target; }
1857     void set_distance_from_target(int d) { _distance_from_target = d; }
1858     GrowableArray<const Node*> edge_bwd; // pointing toward _start
1859     bool is_marked() const { return _mark; } // marked to keep during select
1860     void set_mark() { _mark = true; }
1861   private:
1862     const Node* _node;
1863     int _distance_from_start; // distance from _start
1864     int _distance_from_target = 0; // distance from _target if _all_paths
1865     bool _mark = false;
1866   };
1867   Dict _info_uid;            // Node -> uid
1868   GrowableArray<Info> _info; // uid  -> info
1869 
1870   Info* find_info(const Node* n) {
1871     size_t uid = (size_t)_info_uid[n];
1872     if (uid == 0) {
1873       return nullptr;
1874     }
1875     return &_info.at((int)uid);
1876   }
1877 
1878   void make_info(const Node* node, const int distance) {
1879     assert(find_info(node) == nullptr, "node does not yet have info");
1880     size_t uid = _info.length() + 1;
1881     _info_uid.Insert((void*)node, (void*)uid);
1882     _info.at_put_grow((int)uid, Info(node, distance));
1883     assert(find_info(node)->node() == node, "stored correct node");
1884   };
1885 
1886   // filled by sort, printed by print
1887   GrowableArray<const Node*> _print_list;
1888 
1889   // print header + node table
1890   void print_header() const;
1891   void print_node(const Node* n);
1892 };
1893 
1894 void PrintBFS::run() {
1895   if (!configure()) {
1896     return;
1897   }
1898   collect();
1899   select();
1900   sort();
1901   print();
1902 }
1903 
1904 // set up configuration for BFS and print
1905 bool PrintBFS::configure() {
1906   if (_max_distance < 0) {
1907     _output->print_cr("dump_bfs: max_distance must be non-negative!");
1908     return false;
1909   }
1910   return parse_options();
1911 }
1912 
1913 // BFS traverse according to configuration, fill worklist and info
1914 void PrintBFS::collect() {
1915   maybe_traverse(_start, _start);
1916   int pos = 0;
1917   while (pos < _worklist.length()) {
1918     const Node* n = _worklist.at(pos++); // next node to traverse
1919     Info* info = find_info(n);
1920     if (!_filter_visit.accepts(n) && n != _start) {
1921       continue; // we hit boundary, do not traverse further
1922     }
1923     if (n != _start && n->is_Root()) {
1924       continue; // traversing through root node would lead to unrelated nodes
1925     }
1926     if (_traverse_inputs && _max_distance > info->distance()) {
1927       for (uint i = 0; i < n->req(); i++) {
1928         maybe_traverse(n, n->in(i));
1929       }
1930     }
1931     if (_traverse_outputs && _max_distance > info->distance()) {
1932       for (uint i = 0; i < n->outcnt(); i++) {
1933         maybe_traverse(n, n->raw_out(i));
1934       }
1935     }
1936   }
1937 }
1938 
1939 // go through work list, mark those that we want to print
1940 void PrintBFS::select() {
1941   if (_target == nullptr ) {
1942     select_all();
1943   } else {
1944     if (find_info(_target) == nullptr) {
1945       _output->print_cr("Could not find target in BFS.");
1946       return;
1947     }
1948     if (_all_paths) {
1949       select_all_paths();
1950     } else {
1951       select_shortest_path();
1952     }
1953   }
1954 }
1955 
1956 // take all nodes from BFS
1957 void PrintBFS::select_all() {
1958   for (int i = 0; i < _worklist.length(); i++) {
1959     const Node* n = _worklist.at(i);
1960     Info* info = find_info(n);
1961     info->set_mark();
1962   }
1963 }
1964 
1965 // traverse backward from target, along edges found in BFS
1966 void PrintBFS::select_all_paths() {
1967   int pos = 0;
1968   GrowableArray<const Node*> backtrace;
1969   // start from target
1970   backtrace.push(_target);
1971   find_info(_target)->set_mark();
1972   // traverse backward
1973   while (pos < backtrace.length()) {
1974     const Node* n = backtrace.at(pos++);
1975     Info* info = find_info(n);
1976     for (int i = 0; i < info->edge_bwd.length(); i++) {
1977       // all backward edges
1978       const Node* back = info->edge_bwd.at(i);
1979       Info* back_info = find_info(back);
1980       if (!back_info->is_marked()) {
1981         // not yet found this on way back.
1982         back_info->set_distance_from_target(info->distance_from_target() + 1);
1983         if (back_info->distance_from_target() + back_info->distance() <= _max_distance) {
1984           // total distance is small enough
1985           back_info->set_mark();
1986           backtrace.push(back);
1987         }
1988       }
1989     }
1990   }
1991 }
1992 
1993 void PrintBFS::select_shortest_path() {
1994   const Node* current = _target;
1995   while (true) {
1996     Info* info = find_info(current);
1997     info->set_mark();
1998     if (current == _start) {
1999       break;
2000     }
2001     // first edge -> leads us one step closer to _start
2002     current = info->edge_bwd.at(0);
2003   }
2004 }
2005 
2006 // go through worklist in desired order, put the marked ones in print list
2007 void PrintBFS::sort() {
2008   if (_traverse_inputs && !_traverse_outputs) {
2009     // reverse order
2010     for (int i = _worklist.length() - 1; i >= 0; i--) {
2011       const Node* n = _worklist.at(i);
2012       Info* info = find_info(n);
2013       if (info->is_marked()) {
2014         _print_list.push(n);
2015       }
2016     }
2017   } else {
2018     // same order as worklist
2019     for (int i = 0; i < _worklist.length(); i++) {
2020       const Node* n = _worklist.at(i);
2021       Info* info = find_info(n);
2022       if (info->is_marked()) {
2023         _print_list.push(n);
2024       }
2025     }
2026   }
2027   if (_sort_idx) {
2028     _print_list.sort(node_idx_cmp);
2029   }
2030 }
2031 
2032 // go through printlist and print
2033 void PrintBFS::print() {
2034   if (_print_list.length() > 0 ) {
2035     print_header();
2036     for (int i = 0; i < _print_list.length(); i++) {
2037       const Node* n = _print_list.at(i);
2038       print_node(n);
2039     }
2040   } else {
2041     _output->print_cr("No nodes to print.");
2042   }
2043 }
2044 
2045 void PrintBFS::print_options_help(bool print_examples) {
2046   _output->print_cr("Usage: node->dump_bfs(int max_distance, Node* target, char* options)");
2047   _output->print_cr("");
2048   _output->print_cr("Use cases:");
2049   _output->print_cr("  BFS traversal: no target required");
2050   _output->print_cr("  shortest path: set target");
2051   _output->print_cr("  all paths: set target and put 'A' in options");
2052   _output->print_cr("  detect loop: subcase of all paths, have start==target");
2053   _output->print_cr("");
2054   _output->print_cr("Arguments:");
2055   _output->print_cr("  this/start: staring point of BFS");
2056   _output->print_cr("  target:");
2057   _output->print_cr("    if null: simple BFS");
2058   _output->print_cr("    else: shortest path or all paths between this/start and target");
2059   _output->print_cr("  options:");
2060   _output->print_cr("    if null: same as \"cdmox@B\"");
2061   _output->print_cr("    else: use combination of following characters");
2062   _output->print_cr("      h: display this help info");
2063   _output->print_cr("      H: display this help info, with examples");
2064   _output->print_cr("      +: traverse in-edges (on if neither + nor -)");
2065   _output->print_cr("      -: traverse out-edges");
2066   _output->print_cr("      c: visit control nodes");
2067   _output->print_cr("      d: visit data nodes");
2068   _output->print_cr("      m: visit memory nodes");
2069   _output->print_cr("      o: visit other nodes");
2070   _output->print_cr("      x: visit mixed nodes");
2071   _output->print_cr("      C: boundary control nodes");
2072   _output->print_cr("      D: boundary data nodes");
2073   _output->print_cr("      M: boundary memory nodes");
2074   _output->print_cr("      O: boundary other nodes");
2075   _output->print_cr("      X: boundary mixed nodes");
2076   _output->print_cr("      #: display node category in color (not supported in all terminals)");
2077   _output->print_cr("      S: sort displayed nodes by node idx");
2078   _output->print_cr("      A: all paths (not just shortest path to target)");
2079   _output->print_cr("      @: print old nodes - before matching (if available)");
2080   _output->print_cr("      B: print scheduling blocks (if available)");
2081   _output->print_cr("      $: dump only, no header, no other columns");
2082   _output->print_cr("");
2083   _output->print_cr("recursively follow edges to nodes with permitted visit types,");
2084   _output->print_cr("on the boundary additionally display nodes allowed in boundary types");
2085   _output->print_cr("Note: the categories can be overlapping. For example a mixed node");
2086   _output->print_cr("      can contain control and memory output. Some from the other");
2087   _output->print_cr("      category are also control (Halt, Return, etc).");
2088   _output->print_cr("");
2089   _output->print_cr("output columns:");
2090   _output->print_cr("  dist:  BFS distance to this/start");
2091   _output->print_cr("  apd:   all paths distance (d_outputart + d_target)");
2092   _output->print_cr("  block: block identifier, based on _pre_order");
2093   _output->print_cr("  head:  first node in block");
2094   _output->print_cr("  idom:  head node of idom block");
2095   _output->print_cr("  depth: depth of block (_dom_depth)");
2096   _output->print_cr("  old:   old IR node - before matching");
2097   _output->print_cr("  dump:  node->dump()");
2098   _output->print_cr("");
2099   _output->print_cr("Note: if none of the \"cmdxo\" characters are in the options string");
2100   _output->print_cr("      then we set all of them.");
2101   _output->print_cr("      This allows for short strings like \"#\" for colored input traversal");
2102   _output->print_cr("      or \"-#\" for colored output traversal.");
2103   if (print_examples) {
2104     _output->print_cr("");
2105     _output->print_cr("Examples:");
2106     _output->print_cr("  if->dump_bfs(10, 0, \"+cxo\")");
2107     _output->print_cr("    starting at some if node, traverse inputs recursively");
2108     _output->print_cr("    only along control (mixed and other can also be control)");
2109     _output->print_cr("  phi->dump_bfs(5, 0, \"-dxo\")");
2110     _output->print_cr("    starting at phi node, traverse outputs recursively");
2111     _output->print_cr("    only along data (mixed and other can also have data flow)");
2112     _output->print_cr("  find_node(385)->dump_bfs(3, 0, \"cdmox+#@B\")");
2113     _output->print_cr("    find inputs of node 385, up to 3 nodes up (+)");
2114     _output->print_cr("    traverse all nodes (cdmox), use colors (#)");
2115     _output->print_cr("    display old nodes and blocks, if they exist");
2116     _output->print_cr("    useful call to start with");
2117     _output->print_cr("  find_node(102)->dump_bfs(10, 0, \"dCDMOX-\")");
2118     _output->print_cr("    find non-data dependencies of a data node");
2119     _output->print_cr("    follow data node outputs until we find another category");
2120     _output->print_cr("    node as the boundary");
2121     _output->print_cr("  x->dump_bfs(10, y, 0)");
2122     _output->print_cr("    find shortest path from x to y, along any edge or node");
2123     _output->print_cr("    will not find a path if it is longer than 10");
2124     _output->print_cr("    useful to find how x and y are related");
2125     _output->print_cr("  find_node(741)->dump_bfs(20, find_node(746), \"c+\")");
2126     _output->print_cr("    find shortest control path between two nodes");
2127     _output->print_cr("  find_node(741)->dump_bfs(8, find_node(746), \"cdmox+A\")");
2128     _output->print_cr("    find all paths (A) between two nodes of length at most 8");
2129     _output->print_cr("  find_node(741)->dump_bfs(7, find_node(741), \"c+A\")");
2130     _output->print_cr("    find all control loops for this node");
2131   }
2132 }
2133 
2134 bool PrintBFS::parse_options() {
2135   if (_options == nullptr) {
2136     _options = "cdmox@B"; // default options
2137   }
2138   size_t len = strlen(_options);
2139   for (size_t i = 0; i < len; i++) {
2140     switch (_options[i]) {
2141       case '+':
2142         _traverse_inputs = true;
2143         break;
2144       case '-':
2145         _traverse_outputs = true;
2146         break;
2147       case 'c':
2148         _filter_visit._control = true;
2149         break;
2150       case 'm':
2151         _filter_visit._memory = true;
2152         break;
2153       case 'd':
2154         _filter_visit._data = true;
2155         break;
2156       case 'x':
2157         _filter_visit._mixed = true;
2158         break;
2159       case 'o':
2160         _filter_visit._other = true;
2161         break;
2162       case 'C':
2163         _filter_boundary._control = true;
2164         break;
2165       case 'M':
2166         _filter_boundary._memory = true;
2167         break;
2168       case 'D':
2169         _filter_boundary._data = true;
2170         break;
2171       case 'X':
2172         _filter_boundary._mixed = true;
2173         break;
2174       case 'O':
2175         _filter_boundary._other = true;
2176         break;
2177       case 'S':
2178         _sort_idx = true;
2179         break;
2180       case 'A':
2181         _all_paths = true;
2182         break;
2183       case '#':
2184         _use_color = true;
2185         break;
2186       case 'B':
2187         _print_blocks = true;
2188         break;
2189       case '@':
2190         _print_old = true;
2191         break;
2192       case '$':
2193         _dump_only = true;
2194         break;
2195       case 'h':
2196         print_options_help(false);
2197         return false;
2198        case 'H':
2199         print_options_help(true);
2200         return false;
2201       default:
2202         _output->print_cr("dump_bfs: Unrecognized option \'%c\'", _options[i]);
2203         _output->print_cr("for help, run: find_node(0)->dump_bfs(0,0,\"H\")");
2204         return false;
2205     }
2206   }
2207   if (!_traverse_inputs && !_traverse_outputs) {
2208     _traverse_inputs = true;
2209   }
2210   if (_filter_visit.is_empty()) {
2211     _filter_visit.set_all();
2212   }
2213   Compile* C = Compile::current();
2214   _print_old &= (C->matcher() != nullptr); // only show old if there are new
2215   _print_blocks &= (C->cfg() != nullptr); // only show blocks if available
2216   return true;
2217 }
2218 
2219 void PrintBFS::DumpConfigColored::pre_dump(outputStream* st, const Node* n) {
2220   if (!_bfs->_use_color) {
2221     return;
2222   }
2223   Info* info = _bfs->find_info(n);
2224   if (info == nullptr || !info->is_marked()) {
2225     return;
2226   }
2227 
2228   const Type* t = n->bottom_type();
2229   switch (t->category()) {
2230     case Type::Category::Data:
2231       st->print("\u001b[34m");
2232       break;
2233     case Type::Category::Memory:
2234       st->print("\u001b[32m");
2235       break;
2236     case Type::Category::Mixed:
2237       st->print("\u001b[35m");
2238       break;
2239     case Type::Category::Control:
2240       st->print("\u001b[31m");
2241       break;
2242     case Type::Category::Other:
2243       st->print("\u001b[33m");
2244       break;
2245     case Type::Category::Undef:
2246       n->dump();
2247       assert(false, "category undef ??");
2248       break;
2249     default:
2250       n->dump();
2251       assert(false, "not covered");
2252       break;
2253   }
2254 }
2255 
2256 void PrintBFS::DumpConfigColored::post_dump(outputStream* st) {
2257   if (!_bfs->_use_color) {
2258     return;
2259   }
2260   st->print("\u001b[0m"); // white
2261 }
2262 
2263 Node* PrintBFS::old_node(const Node* n) {
2264   Compile* C = Compile::current();
2265   if (C->matcher() == nullptr || !C->node_arena()->contains(n)) {
2266     return (Node*)nullptr;
2267   } else {
2268     return C->matcher()->find_old_node(n);
2269   }
2270 }
2271 
2272 void PrintBFS::print_node_idx(const Node* n) {
2273   Compile* C = Compile::current();
2274   char buf[30];
2275   if (n == nullptr) {
2276     os::snprintf_checked(buf, sizeof(buf), "_");           // null
2277   } else if (C->node_arena()->contains(n)) {
2278     os::snprintf_checked(buf, sizeof(buf), "%d", n->_idx);  // new node
2279   } else {
2280     os::snprintf_checked(buf, sizeof(buf), "o%d", n->_idx); // old node
2281   }
2282   _output->print("%6s", buf);
2283 }
2284 
2285 void PrintBFS::print_block_id(const Block* b) {
2286   Compile* C = Compile::current();
2287   char buf[30];
2288   os::snprintf_checked(buf, sizeof(buf), "B%d", b->_pre_order);
2289   _output->print("%7s", buf);
2290 }
2291 
2292 void PrintBFS::print_node_block(const Node* n) {
2293   Compile* C = Compile::current();
2294   Block* b = C->node_arena()->contains(n)
2295              ? C->cfg()->get_block_for_node(n)
2296              : nullptr; // guard against old nodes
2297   if (b == nullptr) {
2298     _output->print("      _"); // Block
2299     _output->print("     _");  // head
2300     _output->print("     _");  // idom
2301     _output->print("      _"); // depth
2302   } else {
2303     print_block_id(b);
2304     print_node_idx(b->head());
2305     if (b->_idom) {
2306       print_node_idx(b->_idom->head());
2307     } else {
2308       _output->print("     _"); // idom
2309     }
2310     _output->print("%6d ", b->_dom_depth);
2311   }
2312 }
2313 
2314 // filter, and add to worklist, add info, note traversal edges
2315 void PrintBFS::maybe_traverse(const Node* src, const Node* dst) {
2316   if (dst != nullptr &&
2317      (_filter_visit.accepts(dst) ||
2318       _filter_boundary.accepts(dst) ||
2319       dst == _start)) { // correct category or start?
2320     if (find_info(dst) == nullptr) {
2321       // never visited - set up info
2322       _worklist.push(dst);
2323       int d = 0;
2324       if (dst != _start) {
2325         d = find_info(src)->distance() + 1;
2326       }
2327       make_info(dst, d);
2328     }
2329     if (src != dst) {
2330       // traversal edges useful during select
2331       find_info(dst)->edge_bwd.push(src);
2332     }
2333   }
2334 }
2335 
2336 void PrintBFS::print_header() const {
2337   if (_dump_only) {
2338     return; // no header in dump only mode
2339   }
2340   _output->print("dist");                         // distance
2341   if (_all_paths) {
2342     _output->print(" apd");                       // all paths distance
2343   }
2344   if (_print_blocks) {
2345     _output->print(" [block  head  idom depth]"); // block
2346   }
2347   if (_print_old) {
2348     _output->print("   old");                     // old node
2349   }
2350   _output->print(" dump\n");                      // node dump
2351   _output->print_cr("---------------------------------------------");
2352 }
2353 
2354 void PrintBFS::print_node(const Node* n) {
2355   if (_dump_only) {
2356     n->dump("\n", false, _output, &_dcc);
2357     return;
2358   }
2359   _output->print("%4d", find_info(n)->distance());// distance
2360   if (_all_paths) {
2361     Info* info = find_info(n);
2362     int apd = info->distance() + info->distance_from_target();
2363     _output->print("%4d", apd);                   // all paths distance
2364   }
2365   if (_print_blocks) {
2366     print_node_block(n);                          // block
2367   }
2368   if (_print_old) {
2369     print_node_idx(old_node(n));                  // old node
2370   }
2371   _output->print(" ");
2372   n->dump("\n", false, _output, &_dcc);           // node dump
2373 }
2374 
2375 //------------------------------dump_bfs--------------------------------------
2376 // Call this from debugger
2377 // Useful for BFS traversal, shortest path, all path, loop detection, etc
2378 // Designed to be more readable, and provide additional info
2379 // To find all options, run:
2380 //   find_node(0)->dump_bfs(0,0,"H")
2381 void Node::dump_bfs(const int max_distance, Node* target, const char* options) const {
2382   dump_bfs(max_distance, target, options, tty);
2383 }
2384 
2385 // Used to dump to stream.
2386 void Node::dump_bfs(const int max_distance, Node* target, const char* options, outputStream* st) const {
2387   PrintBFS bfs(this, max_distance, target, options, st);
2388   bfs.run();
2389 }
2390 
2391 // Call this from debugger, with default arguments
2392 void Node::dump_bfs(const int max_distance) const {
2393   dump_bfs(max_distance, nullptr, nullptr);
2394 }
2395 
2396 // -----------------------------dump_idx---------------------------------------
2397 void Node::dump_idx(bool align, outputStream* st, DumpConfig* dc) const {
2398   if (dc != nullptr) {
2399     dc->pre_dump(st, this);
2400   }
2401   Compile* C = Compile::current();
2402   bool is_new = C->node_arena()->contains(this);
2403   if (align) { // print prefix empty spaces$
2404     // +1 for leading digit, +1 for "o"
2405     uint max_width = static_cast<uint>(log10(static_cast<double>(C->unique()))) + 2;
2406     // +1 for leading digit, maybe +1 for "o"
2407     uint width = static_cast<uint>(log10(static_cast<double>(_idx))) + 1 + (is_new ? 0 : 1);
2408     while (max_width > width) {
2409       st->print(" ");
2410       width++;
2411     }
2412   }
2413   if (!is_new) {
2414     st->print("o");
2415   }
2416   st->print("%d", _idx);
2417   if (dc != nullptr) {
2418     dc->post_dump(st);
2419   }
2420 }
2421 
2422 // -----------------------------dump_name--------------------------------------
2423 void Node::dump_name(outputStream* st, DumpConfig* dc) const {
2424   if (dc != nullptr) {
2425     dc->pre_dump(st, this);
2426   }
2427   st->print("%s", Name());
2428   if (dc != nullptr) {
2429     dc->post_dump(st);
2430   }
2431 }
2432 
2433 // -----------------------------Name-------------------------------------------
2434 extern const char *NodeClassNames[];
2435 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
2436 
2437 static bool is_disconnected(const Node* n) {
2438   for (uint i = 0; i < n->req(); i++) {
2439     if (n->in(i) != nullptr)  return false;
2440   }
2441   return true;
2442 }
2443 
2444 #ifdef ASSERT
2445 void Node::dump_orig(outputStream *st, bool print_key) const {
2446   Compile* C = Compile::current();
2447   Node* orig = _debug_orig;
2448   if (not_a_node(orig)) orig = nullptr;
2449   if (orig != nullptr && !C->node_arena()->contains(orig)) orig = nullptr;
2450   if (orig == nullptr) return;
2451   if (print_key) {
2452     st->print(" !orig=");
2453   }
2454   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
2455   if (not_a_node(fast)) fast = nullptr;
2456   while (orig != nullptr) {
2457     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
2458     if (discon) st->print("[");
2459     if (!Compile::current()->node_arena()->contains(orig))
2460       st->print("o");
2461     st->print("%d", orig->_idx);
2462     if (discon) st->print("]");
2463     orig = orig->debug_orig();
2464     if (not_a_node(orig)) orig = nullptr;
2465     if (orig != nullptr && !C->node_arena()->contains(orig)) orig = nullptr;
2466     if (orig != nullptr) st->print(",");
2467     if (fast != nullptr) {
2468       // Step fast twice for each single step of orig:
2469       fast = fast->debug_orig();
2470       if (not_a_node(fast)) fast = nullptr;
2471       if (fast != nullptr && fast != orig) {
2472         fast = fast->debug_orig();
2473         if (not_a_node(fast)) fast = nullptr;
2474       }
2475       if (fast == orig) {
2476         st->print("...");
2477         break;
2478       }
2479     }
2480   }
2481 }
2482 
2483 void Node::set_debug_orig(Node* orig) {
2484   _debug_orig = orig;
2485   if (BreakAtNode == 0)  return;
2486   if (not_a_node(orig))  orig = nullptr;
2487   int trip = 10;
2488   while (orig != nullptr) {
2489     if (orig->debug_idx() == BreakAtNode || (uintx)orig->_idx == BreakAtNode) {
2490       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=" UINT64_FORMAT " orig._idx=%d orig._debug_idx=" UINT64_FORMAT,
2491                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
2492       BREAKPOINT;
2493     }
2494     orig = orig->debug_orig();
2495     if (not_a_node(orig))  orig = nullptr;
2496     if (trip-- <= 0)  break;
2497   }
2498 }
2499 #endif //ASSERT
2500 
2501 //------------------------------dump------------------------------------------
2502 // Dump a Node
2503 void Node::dump(const char* suffix, bool mark, outputStream* st, DumpConfig* dc) const {
2504   Compile* C = Compile::current();
2505   bool is_new = C->node_arena()->contains(this);
2506   C->_in_dump_cnt++;
2507 
2508   // idx mark name ===
2509   dump_idx(true, st, dc);
2510   st->print(mark ? " >" : "  ");
2511   dump_name(st, dc);
2512   st->print("  === ");
2513 
2514   // Dump the required and precedence inputs
2515   dump_req(st, dc);
2516   dump_prec(st, dc);
2517   // Dump the outputs
2518   dump_out(st, dc);
2519 
2520   if (is_disconnected(this)) {
2521 #ifdef ASSERT
2522     st->print("  [" UINT64_FORMAT "]", debug_idx());
2523     dump_orig(st);
2524 #endif
2525     st->cr();
2526     C->_in_dump_cnt--;
2527     return;                     // don't process dead nodes
2528   }
2529 
2530   if (C->clone_map().value(_idx) != 0) {
2531     C->clone_map().dump(_idx, st);
2532   }
2533   // Dump node-specific info
2534   dump_spec(st);
2535 #ifdef ASSERT
2536   // Dump the non-reset _debug_idx
2537   if (Verbose && WizardMode) {
2538     st->print("  [" UINT64_FORMAT "]", debug_idx());
2539   }
2540 #endif
2541 
2542   const Type *t = bottom_type();
2543 
2544   if (t != nullptr && (t->isa_instptr() || t->isa_instklassptr())) {
2545     const TypeInstPtr  *toop = t->isa_instptr();
2546     const TypeInstKlassPtr *tkls = t->isa_instklassptr();
2547     if (toop) {
2548       st->print("  Oop:");
2549     } else if (tkls) {
2550       st->print("  Klass:");
2551     }
2552     t->dump_on(st);
2553   } else if (t == Type::MEMORY) {
2554     st->print("  Memory:");
2555     MemNode::dump_adr_type(this, adr_type(), st);
2556   } else if (Verbose || WizardMode) {
2557     st->print("  Type:");
2558     if (t) {
2559       t->dump_on(st);
2560     } else {
2561       st->print("no type");
2562     }
2563   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
2564     // Dump MachSpillcopy vector type.
2565     t->dump_on(st);
2566   }
2567   if (is_new) {
2568     DEBUG_ONLY(dump_orig(st));
2569     Node_Notes* nn = C->node_notes_at(_idx);
2570     if (nn != nullptr && !nn->is_clear()) {
2571       if (nn->jvms() != nullptr) {
2572         st->print(" !jvms:");
2573         nn->jvms()->dump_spec(st);
2574       }
2575     }
2576   }
2577   if (suffix) st->print("%s", suffix);
2578   C->_in_dump_cnt--;
2579 }
2580 
2581 // call from debugger: dump node to tty with newline
2582 void Node::dump() const {
2583   dump("\n");
2584 }
2585 
2586 //------------------------------dump_req--------------------------------------
2587 void Node::dump_req(outputStream* st, DumpConfig* dc) const {
2588   // Dump the required input edges
2589   for (uint i = 0; i < req(); i++) {    // For all required inputs
2590     Node* d = in(i);
2591     if (d == nullptr) {
2592       st->print("_ ");
2593     } else if (not_a_node(d)) {
2594       st->print("not_a_node ");  // uninitialized, sentinel, garbage, etc.
2595     } else {
2596       d->dump_idx(false, st, dc);
2597       st->print(" ");
2598     }
2599   }
2600 }
2601 
2602 
2603 //------------------------------dump_prec-------------------------------------
2604 void Node::dump_prec(outputStream* st, DumpConfig* dc) const {
2605   // Dump the precedence edges
2606   int any_prec = 0;
2607   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
2608     Node* p = in(i);
2609     if (p != nullptr) {
2610       if (!any_prec++) st->print(" |");
2611       if (not_a_node(p)) { st->print("not_a_node "); continue; }
2612       p->dump_idx(false, st, dc);
2613       st->print(" ");
2614     }
2615   }
2616 }
2617 
2618 //------------------------------dump_out--------------------------------------
2619 void Node::dump_out(outputStream* st, DumpConfig* dc) const {
2620   // Delimit the output edges
2621   st->print(" [[ ");
2622   // Dump the output edges
2623   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
2624     Node* u = _out[i];
2625     if (u == nullptr) {
2626       st->print("_ ");
2627     } else if (not_a_node(u)) {
2628       st->print("not_a_node ");
2629     } else {
2630       u->dump_idx(false, st, dc);
2631       st->print(" ");
2632     }
2633   }
2634   st->print("]] ");
2635 }
2636 
2637 //------------------------------dump-------------------------------------------
2638 // call from debugger: dump Node's inputs (or outputs if d negative)
2639 void Node::dump(int d) const {
2640   dump_bfs(abs(d), nullptr, (d > 0) ? "+$" : "-$");
2641 }
2642 
2643 //------------------------------dump_ctrl--------------------------------------
2644 // call from debugger: dump Node's control inputs (or outputs if d negative)
2645 void Node::dump_ctrl(int d) const {
2646   dump_bfs(abs(d), nullptr, (d > 0) ? "+$c" : "-$c");
2647 }
2648 
2649 //-----------------------------dump_compact------------------------------------
2650 void Node::dump_comp() const {
2651   this->dump_comp("\n");
2652 }
2653 
2654 //-----------------------------dump_compact------------------------------------
2655 // Dump a Node in compact representation, i.e., just print its name and index.
2656 // Nodes can specify additional specifics to print in compact representation by
2657 // implementing dump_compact_spec.
2658 void Node::dump_comp(const char* suffix, outputStream *st) const {
2659   Compile* C = Compile::current();
2660   C->_in_dump_cnt++;
2661   st->print("%s(%d)", Name(), _idx);
2662   this->dump_compact_spec(st);
2663   if (suffix) {
2664     st->print("%s", suffix);
2665   }
2666   C->_in_dump_cnt--;
2667 }
2668 
2669 // VERIFICATION CODE
2670 // Verify all nodes if verify_depth is negative
2671 void Node::verify(int verify_depth, VectorSet& visited, Node_List& worklist) {
2672   assert(verify_depth != 0, "depth should not be 0");
2673   Compile* C = Compile::current();
2674   uint last_index_on_current_depth = worklist.size() - 1;
2675   verify_depth--; // Visiting the first node on depth 1
2676   // Only add nodes to worklist if verify_depth is negative (visit all nodes) or greater than 0
2677   bool add_to_worklist = verify_depth != 0;
2678 
2679   for (uint list_index = 0; list_index < worklist.size(); list_index++) {
2680     Node* n = worklist[list_index];
2681 
2682     if (n->is_Con() && n->bottom_type() == Type::TOP) {
2683       if (C->cached_top_node() == nullptr) {
2684         C->set_cached_top_node((Node*)n);
2685       }
2686       assert(C->cached_top_node() == n, "TOP node must be unique");
2687     }
2688 
2689     uint in_len = n->len();
2690     for (uint i = 0; i < in_len; i++) {
2691       Node* x = n->_in[i];
2692       if (!x || x->is_top()) {
2693         continue;
2694       }
2695 
2696       // Verify my input has a def-use edge to me
2697       // Count use-def edges from n to x
2698       int cnt = 1;
2699       for (uint j = 0; j < i; j++) {
2700         if (n->_in[j] == x) {
2701           cnt++;
2702           break;
2703         }
2704       }
2705       if (cnt == 2) {
2706         // x is already checked as n's previous input, skip its duplicated def-use count checking
2707         continue;
2708       }
2709       for (uint j = i + 1; j < in_len; j++) {
2710         if (n->_in[j] == x) {
2711           cnt++;
2712         }
2713       }
2714 
2715       // Count def-use edges from x to n
2716       uint max = x->_outcnt;
2717       for (uint k = 0; k < max; k++) {
2718         if (x->_out[k] == n) {
2719           cnt--;
2720         }
2721       }
2722       assert(cnt == 0, "mismatched def-use edge counts");
2723 
2724       if (add_to_worklist && !visited.test_set(x->_idx)) {
2725         worklist.push(x);
2726       }
2727     }
2728 
2729     if (verify_depth > 0 && list_index == last_index_on_current_depth) {
2730       // All nodes on this depth were processed and its inputs are on the worklist. Decrement verify_depth and
2731       // store the current last list index which is the last node in the list with the new depth. All nodes
2732       // added afterwards will have a new depth again. Stop adding new nodes if depth limit is reached (=0).
2733       verify_depth--;
2734       if (verify_depth == 0) {
2735         add_to_worklist = false;
2736       }
2737       last_index_on_current_depth = worklist.size() - 1;
2738     }
2739   }
2740 }
2741 #endif // not PRODUCT
2742 
2743 //------------------------------Registers--------------------------------------
2744 // Do we Match on this edge index or not?  Generally false for Control
2745 // and true for everything else.  Weird for calls & returns.
2746 uint Node::match_edge(uint idx) const {
2747   return idx;                   // True for other than index 0 (control)
2748 }
2749 
2750 // Register classes are defined for specific machines
2751 const RegMask &Node::out_RegMask() const {
2752   ShouldNotCallThis();
2753   return RegMask::Empty;
2754 }
2755 
2756 const RegMask &Node::in_RegMask(uint) const {
2757   ShouldNotCallThis();
2758   return RegMask::Empty;
2759 }
2760 
2761 void Node_Array::grow(uint i) {
2762   assert(_max > 0, "invariant");
2763   uint old = _max;
2764   _max = next_power_of_2(i);
2765   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2766   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2767 }
2768 
2769 void Node_Array::insert(uint i, Node* n) {
2770   if (_nodes[_max - 1]) {
2771     grow(_max);
2772   }
2773   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i + 1], ((_max - i - 1) * sizeof(Node*)));
2774   _nodes[i] = n;
2775 }
2776 
2777 void Node_Array::remove(uint i) {
2778   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i + 1], (HeapWord*)&_nodes[i], ((_max - i - 1) * sizeof(Node*)));
2779   _nodes[_max - 1] = nullptr;
2780 }
2781 
2782 void Node_Array::dump() const {
2783 #ifndef PRODUCT
2784   for (uint i = 0; i < _max; i++) {
2785     Node* nn = _nodes[i];
2786     if (nn != nullptr) {
2787       tty->print("%5d--> ",i); nn->dump();
2788     }
2789   }
2790 #endif
2791 }
2792 
2793 //--------------------------is_iteratively_computed------------------------------
2794 // Operation appears to be iteratively computed (such as an induction variable)
2795 // It is possible for this operation to return false for a loop-varying
2796 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2797 bool Node::is_iteratively_computed() {
2798   if (ideal_reg()) { // does operation have a result register?
2799     for (uint i = 1; i < req(); i++) {
2800       Node* n = in(i);
2801       if (n != nullptr && n->is_Phi()) {
2802         for (uint j = 1; j < n->req(); j++) {
2803           if (n->in(j) == this) {
2804             return true;
2805           }
2806         }
2807       }
2808     }
2809   }
2810   return false;
2811 }
2812 
2813 //--------------------------find_similar------------------------------
2814 // Return a node with opcode "opc" and same inputs as "this" if one can
2815 // be found; Otherwise return null;
2816 Node* Node::find_similar(int opc) {
2817   if (req() >= 2) {
2818     Node* def = in(1);
2819     if (def && def->outcnt() >= 2) {
2820       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2821         Node* use = def->fast_out(i);
2822         if (use != this &&
2823             use->Opcode() == opc &&
2824             use->req() == req()) {
2825           uint j;
2826           for (j = 0; j < use->req(); j++) {
2827             if (use->in(j) != in(j)) {
2828               break;
2829             }
2830           }
2831           if (j == use->req()) {
2832             return use;
2833           }
2834         }
2835       }
2836     }
2837   }
2838   return nullptr;
2839 }
2840 
2841 
2842 //--------------------------unique_ctrl_out_or_null-------------------------
2843 // Return the unique control out if only one. Null if none or more than one.
2844 Node* Node::unique_ctrl_out_or_null() const {
2845   Node* found = nullptr;
2846   for (uint i = 0; i < outcnt(); i++) {
2847     Node* use = raw_out(i);
2848     if (use->is_CFG() && use != this) {
2849       if (found != nullptr) {
2850         return nullptr;
2851       }
2852       found = use;
2853     }
2854   }
2855   return found;
2856 }
2857 
2858 //--------------------------unique_ctrl_out------------------------------
2859 // Return the unique control out. Asserts if none or more than one control out.
2860 Node* Node::unique_ctrl_out() const {
2861   Node* ctrl = unique_ctrl_out_or_null();
2862   assert(ctrl != nullptr, "control out is assumed to be unique");
2863   return ctrl;
2864 }
2865 
2866 void Node::ensure_control_or_add_prec(Node* c) {
2867   if (in(0) == nullptr) {
2868     set_req(0, c);
2869   } else if (in(0) != c) {
2870     add_prec(c);
2871   }
2872 }
2873 
2874 bool Node::is_dead_loop_safe() const {
2875   if (is_Phi()) {
2876     return true;
2877   }
2878   if (is_Proj() && in(0) == nullptr)  {
2879     return true;
2880   }
2881   if ((_flags & (Flag_is_dead_loop_safe | Flag_is_Con)) != 0) {
2882     if (!is_Proj()) {
2883       return true;
2884     }
2885     if (in(0)->is_Allocate()) {
2886       return false;
2887     }
2888     // MemNode::can_see_stored_value() peeks through the boxing call
2889     if (in(0)->is_CallStaticJava() && in(0)->as_CallStaticJava()->is_boxing_method()) {
2890       return false;
2891     }
2892     return true;
2893   }
2894   return false;
2895 }
2896 
2897 //=============================================================================
2898 //------------------------------yank-------------------------------------------
2899 // Find and remove
2900 void Node_List::yank( Node *n ) {
2901   uint i;
2902   for (i = 0; i < _cnt; i++) {
2903     if (_nodes[i] == n) {
2904       break;
2905     }
2906   }
2907 
2908   if (i < _cnt) {
2909     _nodes[i] = _nodes[--_cnt];
2910   }
2911 }
2912 
2913 //------------------------------dump-------------------------------------------
2914 void Node_List::dump() const {
2915 #ifndef PRODUCT
2916   for (uint i = 0; i < _cnt; i++) {
2917     if (_nodes[i]) {
2918       tty->print("%5d--> ", i);
2919       _nodes[i]->dump();
2920     }
2921   }
2922 #endif
2923 }
2924 
2925 void Node_List::dump_simple() const {
2926 #ifndef PRODUCT
2927   for (uint i = 0; i < _cnt; i++) {
2928     if( _nodes[i] ) {
2929       tty->print(" %d", _nodes[i]->_idx);
2930     } else {
2931       tty->print(" null");
2932     }
2933   }
2934 #endif
2935 }
2936 
2937 //=============================================================================
2938 //------------------------------remove-----------------------------------------
2939 void Unique_Node_List::remove(Node* n) {
2940   if (_in_worklist.test(n->_idx)) {
2941     for (uint i = 0; i < size(); i++) {
2942       if (_nodes[i] == n) {
2943         map(i, Node_List::pop());
2944         _in_worklist.remove(n->_idx);
2945         return;
2946       }
2947     }
2948     ShouldNotReachHere();
2949   }
2950 }
2951 
2952 //-----------------------remove_useless_nodes----------------------------------
2953 // Remove useless nodes from worklist
2954 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2955   for (uint i = 0; i < size(); ++i) {
2956     Node *n = at(i);
2957     assert( n != nullptr, "Did not expect null entries in worklist");
2958     if (!useful.test(n->_idx)) {
2959       _in_worklist.remove(n->_idx);
2960       map(i, Node_List::pop());
2961       --i;  // Visit popped node
2962       // If it was last entry, loop terminates since size() was also reduced
2963     }
2964   }
2965 }
2966 
2967 //=============================================================================
2968 void Node_Stack::grow() {
2969   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2970   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2971   size_t max = old_max << 1;             // max * 2
2972   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2973   _inode_max = _inodes + max;
2974   _inode_top = _inodes + old_top;        // restore _top
2975 }
2976 
2977 // Node_Stack is used to map nodes.
2978 Node* Node_Stack::find(uint idx) const {
2979   uint sz = size();
2980   for (uint i = 0; i < sz; i++) {
2981     if (idx == index_at(i)) {
2982       return node_at(i);
2983     }
2984   }
2985   return nullptr;
2986 }
2987 
2988 //=============================================================================
2989 uint TypeNode::size_of() const { return sizeof(*this); }
2990 #ifndef PRODUCT
2991 void TypeNode::dump_spec(outputStream *st) const {
2992   if (!Verbose && !WizardMode) {
2993     // standard dump does this in Verbose and WizardMode
2994     st->print(" #"); _type->dump_on(st);
2995   }
2996 }
2997 
2998 void TypeNode::dump_compact_spec(outputStream *st) const {
2999   st->print("#");
3000   _type->dump_on(st);
3001 }
3002 #endif
3003 uint TypeNode::hash() const {
3004   return Node::hash() + _type->hash();
3005 }
3006 bool TypeNode::cmp(const Node& n) const {
3007   return !Type::cmp(_type, ((TypeNode&)n)._type);
3008 }
3009 const Type* TypeNode::bottom_type() const { return _type; }
3010 const Type* TypeNode::Value(PhaseGVN* phase) const { return _type; }
3011 
3012 //------------------------------ideal_reg--------------------------------------
3013 uint TypeNode::ideal_reg() const {
3014   return _type->ideal_reg();
3015 }