1 /*
   2  * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2024, 2025, Alibaba Group Holding Limited. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  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/inlinetypenode.hpp"
  37 #include "opto/loopnode.hpp"
  38 #include "opto/machnode.hpp"
  39 #include "opto/matcher.hpp"
  40 #include "opto/node.hpp"
  41 #include "opto/opcodes.hpp"
  42 #include "opto/regmask.hpp"
  43 #include "opto/rootnode.hpp"
  44 #include "opto/type.hpp"
  45 #include "utilities/copy.hpp"
  46 #include "utilities/macros.hpp"
  47 #include "utilities/powerOfTwo.hpp"
  48 #include "utilities/stringUtils.hpp"
  49 
  50 class RegMask;
  51 // #include "phase.hpp"
  52 class PhaseTransform;
  53 class PhaseGVN;
  54 
  55 // Arena we are currently building Nodes in
  56 const uint Node::NotAMachineReg = 0xffff0000;
  57 
  58 #ifndef PRODUCT
  59 extern uint nodes_created;
  60 #endif
  61 #ifdef __clang__
  62 #pragma clang diagnostic push
  63 #pragma GCC diagnostic ignored "-Wuninitialized"
  64 #endif
  65 
  66 #ifdef ASSERT
  67 
  68 //-------------------------- construct_node------------------------------------
  69 // Set a breakpoint here to identify where a particular node index is built.
  70 void Node::verify_construction() {
  71   _debug_orig = nullptr;
  72   // The decimal digits of _debug_idx are <compile_id> followed by 10 digits of <_idx>
  73   Compile* C = Compile::current();
  74   assert(C->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  75   uint64_t new_debug_idx = (uint64_t)C->compile_id() * 10000000000 + _idx;
  76   set_debug_idx(new_debug_idx);
  77   if (!C->phase_optimize_finished()) {
  78     // Only check assert during parsing and optimization phase. Skip it while generating code.
  79     assert(C->live_nodes() <= C->max_node_limit(), "Live Node limit exceeded limit");
  80   }
  81   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (uint64_t)_idx == BreakAtNode)) {
  82     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=" UINT64_FORMAT, _idx, _debug_idx);
  83     BREAKPOINT;
  84   }
  85 #if OPTO_DU_ITERATOR_ASSERT
  86   _last_del = nullptr;
  87   _del_tick = 0;
  88 #endif
  89   _hash_lock = 0;
  90 }
  91 
  92 
  93 // #ifdef ASSERT ...
  94 
  95 #if OPTO_DU_ITERATOR_ASSERT
  96 void DUIterator_Common::sample(const Node* node) {
  97   _vdui     = VerifyDUIterators;
  98   _node     = node;
  99   _outcnt   = node->_outcnt;
 100   _del_tick = node->_del_tick;
 101   _last     = nullptr;
 102 }
 103 
 104 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
 105   assert(_node     == node, "consistent iterator source");
 106   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
 107 }
 108 
 109 void DUIterator_Common::verify_resync() {
 110   // Ensure that the loop body has just deleted the last guy produced.
 111   const Node* node = _node;
 112   // Ensure that at least one copy of the last-seen edge was deleted.
 113   // Note:  It is OK to delete multiple copies of the last-seen edge.
 114   // Unfortunately, we have no way to verify that all the deletions delete
 115   // that same edge.  On this point we must use the Honor System.
 116   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 117   assert(node->_last_del == _last, "must have deleted the edge just produced");
 118   // We liked this deletion, so accept the resulting outcnt and tick.
 119   _outcnt   = node->_outcnt;
 120   _del_tick = node->_del_tick;
 121 }
 122 
 123 void DUIterator_Common::reset(const DUIterator_Common& that) {
 124   if (this == &that)  return;  // ignore assignment to self
 125   if (!_vdui) {
 126     // We need to initialize everything, overwriting garbage values.
 127     _last = that._last;
 128     _vdui = that._vdui;
 129   }
 130   // Note:  It is legal (though odd) for an iterator over some node x
 131   // to be reassigned to iterate over another node y.  Some doubly-nested
 132   // progress loops depend on being able to do this.
 133   const Node* node = that._node;
 134   // Re-initialize everything, except _last.
 135   _node     = node;
 136   _outcnt   = node->_outcnt;
 137   _del_tick = node->_del_tick;
 138 }
 139 
 140 void DUIterator::sample(const Node* node) {
 141   DUIterator_Common::sample(node);      // Initialize the assertion data.
 142   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 143 }
 144 
 145 void DUIterator::verify(const Node* node, bool at_end_ok) {
 146   DUIterator_Common::verify(node, at_end_ok);
 147   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 148 }
 149 
 150 void DUIterator::verify_increment() {
 151   if (_refresh_tick & 1) {
 152     // We have refreshed the index during this loop.
 153     // Fix up _idx to meet asserts.
 154     if (_idx > _outcnt)  _idx = _outcnt;
 155   }
 156   verify(_node, true);
 157 }
 158 
 159 void DUIterator::verify_resync() {
 160   // Note:  We do not assert on _outcnt, because insertions are OK here.
 161   DUIterator_Common::verify_resync();
 162   // Make sure we are still in sync, possibly with no more out-edges:
 163   verify(_node, true);
 164 }
 165 
 166 void DUIterator::reset(const DUIterator& that) {
 167   if (this == &that)  return;  // self assignment is always a no-op
 168   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 169   assert(that._idx          == 0, "assign only the result of Node::outs()");
 170   assert(_idx               == that._idx, "already assigned _idx");
 171   if (!_vdui) {
 172     // We need to initialize everything, overwriting garbage values.
 173     sample(that._node);
 174   } else {
 175     DUIterator_Common::reset(that);
 176     if (_refresh_tick & 1) {
 177       _refresh_tick++;                  // Clear the "was refreshed" flag.
 178     }
 179     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 180   }
 181 }
 182 
 183 void DUIterator::refresh() {
 184   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 185   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 186 }
 187 
 188 void DUIterator::verify_finish() {
 189   // If the loop has killed the node, do not require it to re-run.
 190   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 191   // If this assert triggers, it means that a loop used refresh_out_pos
 192   // to re-synch an iteration index, but the loop did not correctly
 193   // re-run itself, using a "while (progress)" construct.
 194   // This iterator enforces the rule that you must keep trying the loop
 195   // until it "runs clean" without any need for refreshing.
 196   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 197 }
 198 
 199 
 200 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 201   DUIterator_Common::verify(node, at_end_ok);
 202   Node** out    = node->_out;
 203   uint   cnt    = node->_outcnt;
 204   assert(cnt == _outcnt, "no insertions allowed");
 205   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 206   // This last check is carefully designed to work for NO_OUT_ARRAY.
 207 }
 208 
 209 void DUIterator_Fast::verify_limit() {
 210   const Node* node = _node;
 211   verify(node, true);
 212   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 213 }
 214 
 215 void DUIterator_Fast::verify_resync() {
 216   const Node* node = _node;
 217   if (_outp == node->_out + _outcnt) {
 218     // Note that the limit imax, not the pointer i, gets updated with the
 219     // exact count of deletions.  (For the pointer it's always "--i".)
 220     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 221     // This is a limit pointer, with a name like "imax".
 222     // Fudge the _last field so that the common assert will be happy.
 223     _last = (Node*) node->_last_del;
 224     DUIterator_Common::verify_resync();
 225   } else {
 226     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 227     // A normal internal pointer.
 228     DUIterator_Common::verify_resync();
 229     // Make sure we are still in sync, possibly with no more out-edges:
 230     verify(node, true);
 231   }
 232 }
 233 
 234 void DUIterator_Fast::verify_relimit(uint n) {
 235   const Node* node = _node;
 236   assert((int)n > 0, "use imax -= n only with a positive count");
 237   // This must be a limit pointer, with a name like "imax".
 238   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 239   // The reported number of deletions must match what the node saw.
 240   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 241   // Fudge the _last field so that the common assert will be happy.
 242   _last = (Node*) node->_last_del;
 243   DUIterator_Common::verify_resync();
 244 }
 245 
 246 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 247   assert(_outp              == that._outp, "already assigned _outp");
 248   DUIterator_Common::reset(that);
 249 }
 250 
 251 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 252   // at_end_ok means the _outp is allowed to underflow by 1
 253   _outp += at_end_ok;
 254   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 255   _outp -= at_end_ok;
 256   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 257 }
 258 
 259 void DUIterator_Last::verify_limit() {
 260   // Do not require the limit address to be resynched.
 261   //verify(node, true);
 262   assert(_outp == _node->_out, "limit still correct");
 263 }
 264 
 265 void DUIterator_Last::verify_step(uint num_edges) {
 266   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 267   _outcnt   -= num_edges;
 268   _del_tick += num_edges;
 269   // Make sure we are still in sync, possibly with no more out-edges:
 270   const Node* node = _node;
 271   verify(node, true);
 272   assert(node->_last_del == _last, "must have deleted the edge just produced");
 273 }
 274 
 275 #endif //OPTO_DU_ITERATOR_ASSERT
 276 
 277 
 278 #endif //ASSERT
 279 
 280 
 281 // This constant used to initialize _out may be any non-null value.
 282 // The value null is reserved for the top node only.
 283 #define NO_OUT_ARRAY ((Node**)-1)
 284 
 285 // Out-of-line code from node constructors.
 286 // Executed only when extra debug info. is being passed around.
 287 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 288   C->set_node_notes_at(idx, nn);
 289 }
 290 
 291 // Shared initialization code.
 292 inline int Node::Init(int req) {
 293   Compile* C = Compile::current();
 294   int idx = C->next_unique();
 295   NOT_PRODUCT(_igv_idx = C->next_igv_idx());
 296 
 297   // Allocate memory for the necessary number of edges.
 298   if (req > 0) {
 299     // Allocate space for _in array to have double alignment.
 300     _in = (Node **) ((char *) (C->node_arena()->AmallocWords(req * sizeof(void*))));
 301   }
 302   // If there are default notes floating around, capture them:
 303   Node_Notes* nn = C->default_node_notes();
 304   if (nn != nullptr)  init_node_notes(C, idx, nn);
 305 
 306   // Note:  At this point, C is dead,
 307   // and we begin to initialize the new Node.
 308 
 309   _cnt = _max = req;
 310   _outcnt = _outmax = 0;
 311   _class_id = Class_Node;
 312   _flags = 0;
 313   _out = NO_OUT_ARRAY;
 314   return idx;
 315 }
 316 
 317 //------------------------------Node-------------------------------------------
 318 // Create a Node, with a given number of required edges.
 319 Node::Node(uint req)
 320   : _idx(Init(req))
 321 #ifdef ASSERT
 322   , _parse_idx(_idx)
 323 #endif
 324 {
 325   assert( req < Compile::current()->max_node_limit() - NodeLimitFudgeFactor, "Input limit exceeded" );
 326   DEBUG_ONLY( verify_construction() );
 327   NOT_PRODUCT(nodes_created++);
 328   if (req == 0) {
 329     _in = nullptr;
 330   } else {
 331     Node** to = _in;
 332     for(uint i = 0; i < req; i++) {
 333       to[i] = nullptr;
 334     }
 335   }
 336 }
 337 
 338 //------------------------------Node-------------------------------------------
 339 Node::Node(Node *n0)
 340   : _idx(Init(1))
 341 #ifdef ASSERT
 342   , _parse_idx(_idx)
 343 #endif
 344 {
 345   DEBUG_ONLY( verify_construction() );
 346   NOT_PRODUCT(nodes_created++);
 347   assert( is_not_dead(n0), "can not use dead node");
 348   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 349 }
 350 
 351 //------------------------------Node-------------------------------------------
 352 Node::Node(Node *n0, Node *n1)
 353   : _idx(Init(2))
 354 #ifdef ASSERT
 355   , _parse_idx(_idx)
 356 #endif
 357 {
 358   DEBUG_ONLY( verify_construction() );
 359   NOT_PRODUCT(nodes_created++);
 360   assert( is_not_dead(n0), "can not use dead node");
 361   assert( is_not_dead(n1), "can not use dead node");
 362   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 363   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 364 }
 365 
 366 //------------------------------Node-------------------------------------------
 367 Node::Node(Node *n0, Node *n1, Node *n2)
 368   : _idx(Init(3))
 369 #ifdef ASSERT
 370   , _parse_idx(_idx)
 371 #endif
 372 {
 373   DEBUG_ONLY( verify_construction() );
 374   NOT_PRODUCT(nodes_created++);
 375   assert( is_not_dead(n0), "can not use dead node");
 376   assert( is_not_dead(n1), "can not use dead node");
 377   assert( is_not_dead(n2), "can not use dead node");
 378   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 379   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 380   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 381 }
 382 
 383 //------------------------------Node-------------------------------------------
 384 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 385   : _idx(Init(4))
 386 #ifdef ASSERT
 387   , _parse_idx(_idx)
 388 #endif
 389 {
 390   DEBUG_ONLY( verify_construction() );
 391   NOT_PRODUCT(nodes_created++);
 392   assert( is_not_dead(n0), "can not use dead node");
 393   assert( is_not_dead(n1), "can not use dead node");
 394   assert( is_not_dead(n2), "can not use dead node");
 395   assert( is_not_dead(n3), "can not use dead node");
 396   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 397   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 398   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 399   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 400 }
 401 
 402 //------------------------------Node-------------------------------------------
 403 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 404   : _idx(Init(5))
 405 #ifdef ASSERT
 406   , _parse_idx(_idx)
 407 #endif
 408 {
 409   DEBUG_ONLY( verify_construction() );
 410   NOT_PRODUCT(nodes_created++);
 411   assert( is_not_dead(n0), "can not use dead node");
 412   assert( is_not_dead(n1), "can not use dead node");
 413   assert( is_not_dead(n2), "can not use dead node");
 414   assert( is_not_dead(n3), "can not use dead node");
 415   assert( is_not_dead(n4), "can not use dead node");
 416   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 417   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 418   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 419   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 420   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 421 }
 422 
 423 //------------------------------Node-------------------------------------------
 424 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 425                      Node *n4, Node *n5)
 426   : _idx(Init(6))
 427 #ifdef ASSERT
 428   , _parse_idx(_idx)
 429 #endif
 430 {
 431   DEBUG_ONLY( verify_construction() );
 432   NOT_PRODUCT(nodes_created++);
 433   assert( is_not_dead(n0), "can not use dead node");
 434   assert( is_not_dead(n1), "can not use dead node");
 435   assert( is_not_dead(n2), "can not use dead node");
 436   assert( is_not_dead(n3), "can not use dead node");
 437   assert( is_not_dead(n4), "can not use dead node");
 438   assert( is_not_dead(n5), "can not use dead node");
 439   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 440   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 441   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 442   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 443   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 444   _in[5] = n5; if (n5 != nullptr) n5->add_out((Node *)this);
 445 }
 446 
 447 //------------------------------Node-------------------------------------------
 448 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 449                      Node *n4, Node *n5, Node *n6)
 450   : _idx(Init(7))
 451 #ifdef ASSERT
 452   , _parse_idx(_idx)
 453 #endif
 454 {
 455   DEBUG_ONLY( verify_construction() );
 456   NOT_PRODUCT(nodes_created++);
 457   assert( is_not_dead(n0), "can not use dead node");
 458   assert( is_not_dead(n1), "can not use dead node");
 459   assert( is_not_dead(n2), "can not use dead node");
 460   assert( is_not_dead(n3), "can not use dead node");
 461   assert( is_not_dead(n4), "can not use dead node");
 462   assert( is_not_dead(n5), "can not use dead node");
 463   assert( is_not_dead(n6), "can not use dead node");
 464   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 465   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 466   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 467   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 468   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 469   _in[5] = n5; if (n5 != nullptr) n5->add_out((Node *)this);
 470   _in[6] = n6; if (n6 != nullptr) n6->add_out((Node *)this);
 471 }
 472 
 473 #ifdef __clang__
 474 #pragma clang diagnostic pop
 475 #endif
 476 
 477 
 478 //------------------------------clone------------------------------------------
 479 // Clone a Node.
 480 Node *Node::clone() const {
 481   Compile* C = Compile::current();
 482   uint s = size_of();           // Size of inherited Node
 483   Node *n = (Node*)C->node_arena()->AmallocWords(size_of() + _max*sizeof(Node*));
 484   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 485   // Set the new input pointer array
 486   n->_in = (Node**)(((char*)n)+s);
 487   // Cannot share the old output pointer array, so kill it
 488   n->_out = NO_OUT_ARRAY;
 489   // And reset the counters to 0
 490   n->_outcnt = 0;
 491   n->_outmax = 0;
 492   // Unlock this guy, since he is not in any hash table.
 493   DEBUG_ONLY(n->_hash_lock = 0);
 494   // Walk the old node's input list to duplicate its edges
 495   uint i;
 496   for( i = 0; i < len(); i++ ) {
 497     Node *x = in(i);
 498     n->_in[i] = x;
 499     if (x != nullptr) x->add_out(n);
 500   }
 501   if (is_macro()) {
 502     C->add_macro_node(n);
 503   }
 504   if (is_expensive()) {
 505     C->add_expensive_node(n);
 506   }
 507   if (for_post_loop_opts_igvn()) {
 508     // Don't add cloned node to Compile::_for_post_loop_opts_igvn list automatically.
 509     // If it is applicable, it will happen anyway when the cloned node is registered with IGVN.
 510     n->remove_flag(Node::NodeFlags::Flag_for_post_loop_opts_igvn);
 511   }
 512   if (for_merge_stores_igvn()) {
 513     // Don't add cloned node to Compile::_for_merge_stores_igvn list automatically.
 514     // If it is applicable, it will happen anyway when the cloned node is registered with IGVN.
 515     n->remove_flag(Node::NodeFlags::Flag_for_merge_stores_igvn);
 516   }
 517   if (n->is_ParsePredicate()) {
 518     C->add_parse_predicate(n->as_ParsePredicate());
 519   }
 520   if (n->is_OpaqueTemplateAssertionPredicate()) {
 521     C->add_template_assertion_predicate_opaque(n->as_OpaqueTemplateAssertionPredicate());
 522   }
 523 
 524   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 525   bs->register_potential_barrier_node(n);
 526 
 527   n->set_idx(C->next_unique()); // Get new unique index as well
 528   NOT_PRODUCT(n->_igv_idx = C->next_igv_idx());
 529   DEBUG_ONLY( n->verify_construction() );
 530   NOT_PRODUCT(nodes_created++);
 531   // Do not patch over the debug_idx of a clone, because it makes it
 532   // impossible to break on the clone's moment of creation.
 533   //DEBUG_ONLY( n->set_debug_idx( debug_idx() ) );
 534 
 535   C->copy_node_notes_to(n, (Node*) this);
 536 
 537   // MachNode clone
 538   uint nopnds;
 539   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 540     MachNode *mach  = n->as_Mach();
 541     MachNode *mthis = this->as_Mach();
 542     // Get address of _opnd_array.
 543     // It should be the same offset since it is the clone of this node.
 544     MachOper **from = mthis->_opnds;
 545     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 546                     pointer_delta((const void*)from,
 547                                   (const void*)(&mthis->_opnds), 1));
 548     mach->_opnds = to;
 549     for ( uint i = 0; i < nopnds; ++i ) {
 550       to[i] = from[i]->clone();
 551     }
 552   }
 553   if (this->is_MachProj()) {
 554     // MachProjNodes contain register masks that may contain pointers to
 555     // externally allocated memory. Make sure to use a proper constructor
 556     // instead of just shallowly copying.
 557     MachProjNode* mach = n->as_MachProj();
 558     MachProjNode* mthis = this->as_MachProj();
 559     new (&mach->_rout) RegMask(mthis->_rout);
 560   }
 561   if (n->is_Call()) {
 562     // CallGenerator is linked to the original node.
 563     CallGenerator* cg = n->as_Call()->generator();
 564     if (cg != nullptr) {
 565       CallGenerator* cloned_cg = cg->with_call_node(n->as_Call());
 566       n->as_Call()->set_generator(cloned_cg);
 567     }
 568   }
 569   if (n->is_SafePoint()) {
 570     // Scalar replacement and macro expansion might modify the JVMState.
 571     // Clone it to make sure it's not shared between SafePointNodes.
 572     n->as_SafePoint()->clone_jvms(C);
 573     n->as_SafePoint()->clone_replaced_nodes();
 574   }
 575   if (n->is_InlineType()) {
 576     C->add_inline_type(n);
 577   }
 578   if (n->is_LoadFlat() || n->is_StoreFlat()) {
 579     C->add_flat_access(n);
 580   }
 581   Compile::current()->record_modified_node(n);
 582   return n;                     // Return the clone
 583 }
 584 
 585 //---------------------------setup_is_top--------------------------------------
 586 // Call this when changing the top node, to reassert the invariants
 587 // required by Node::is_top.  See Compile::set_cached_top_node.
 588 void Node::setup_is_top() {
 589   if (this == (Node*)Compile::current()->top()) {
 590     // This node has just become top.  Kill its out array.
 591     _outcnt = _outmax = 0;
 592     _out = nullptr;                           // marker value for top
 593     assert(is_top(), "must be top");
 594   } else {
 595     if (_out == nullptr)  _out = NO_OUT_ARRAY;
 596     assert(!is_top(), "must not be top");
 597   }
 598 }
 599 
 600 //------------------------------~Node------------------------------------------
 601 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 602 void Node::destruct(PhaseValues* phase) {
 603   Compile* compile = (phase != nullptr) ? phase->C : Compile::current();
 604   if (phase != nullptr && phase->is_IterGVN()) {
 605     phase->is_IterGVN()->_worklist.remove(this);
 606   }
 607   // If this is the most recently created node, reclaim its index. Otherwise,
 608   // record the node as dead to keep liveness information accurate.
 609   if ((uint)_idx+1 == compile->unique()) {
 610     compile->set_unique(compile->unique()-1);
 611   } else {
 612     compile->record_dead_node(_idx);
 613   }
 614   // Clear debug info:
 615   Node_Notes* nn = compile->node_notes_at(_idx);
 616   if (nn != nullptr)  nn->clear();
 617   // Walk the input array, freeing the corresponding output edges
 618   _cnt = _max;  // forget req/prec distinction
 619   uint i;
 620   for( i = 0; i < _max; i++ ) {
 621     set_req(i, nullptr);
 622     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 623   }
 624   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 625 
 626   if (is_macro()) {
 627     compile->remove_macro_node(this);
 628   }
 629   if (is_expensive()) {
 630     compile->remove_expensive_node(this);
 631   }
 632   if (is_OpaqueTemplateAssertionPredicate()) {
 633     compile->remove_template_assertion_predicate_opaque(as_OpaqueTemplateAssertionPredicate());
 634   }
 635   if (is_ParsePredicate()) {
 636     compile->remove_parse_predicate(as_ParsePredicate());
 637   }
 638   if (for_post_loop_opts_igvn()) {
 639     compile->remove_from_post_loop_opts_igvn(this);
 640   }
 641   if (is_InlineType()) {
 642     compile->remove_inline_type(this);
 643   }
 644   if (for_merge_stores_igvn()) {
 645     compile->remove_from_merge_stores_igvn(this);
 646   }
 647 
 648   if (is_SafePoint()) {
 649     as_SafePoint()->delete_replaced_nodes();
 650 
 651     if (is_CallStaticJava()) {
 652       compile->remove_unstable_if_trap(as_CallStaticJava(), false);
 653     }
 654   }
 655   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 656   bs->unregister_potential_barrier_node(this);
 657 
 658   // See if the input array was allocated just prior to the object
 659   int edge_size = _max*sizeof(void*);
 660   int out_edge_size = _outmax*sizeof(void*);
 661   char *in_array = ((char*)_in);
 662   char *edge_end = in_array + edge_size;
 663   char *out_array = (char*)(_out == NO_OUT_ARRAY? nullptr: _out);
 664   int node_size = size_of();
 665 
 666 #ifdef ASSERT
 667   // We will not actually delete the storage, but we'll make the node unusable.
 668   compile->remove_modified_node(this);
 669   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 670   _in = _out = (Node**) badAddress;
 671   _max = _cnt = _outmax = _outcnt = 0;
 672 #endif
 673 
 674   // Free the output edge array
 675   if (out_edge_size > 0) {
 676     compile->node_arena()->Afree(out_array, out_edge_size);
 677   }
 678 
 679   // Free the input edge array and the node itself
 680   if( edge_end == (char*)this ) {
 681     // It was; free the input array and object all in one hit
 682 #ifndef ASSERT
 683     compile->node_arena()->Afree(in_array, edge_size+node_size);
 684 #endif
 685   } else {
 686     // Free just the input array
 687     compile->node_arena()->Afree(in_array, edge_size);
 688 
 689     // Free just the object
 690 #ifndef ASSERT
 691     compile->node_arena()->Afree(this, node_size);
 692 #endif
 693   }
 694 }
 695 
 696 // Resize input or output array to grow it to the next larger power-of-2 bigger
 697 // than len.
 698 void Node::resize_array(Node**& array, node_idx_t& max_size, uint len, bool needs_clearing) {
 699   Arena* arena = Compile::current()->node_arena();
 700   uint new_max = max_size;
 701   if (new_max == 0) {
 702     max_size = 4;
 703     array = (Node**)arena->Amalloc(4 * sizeof(Node*));
 704     if (needs_clearing) {
 705       array[0] = nullptr;
 706       array[1] = nullptr;
 707       array[2] = nullptr;
 708       array[3] = nullptr;
 709     }
 710     return;
 711   }
 712   new_max = next_power_of_2(len);
 713   assert(needs_clearing || (array != nullptr && array != NO_OUT_ARRAY), "out must have sensible value");
 714   array = (Node**)arena->Arealloc(array, max_size * sizeof(Node*), new_max * sizeof(Node*));
 715   if (needs_clearing) {
 716     Copy::zero_to_bytes(&array[max_size], (new_max - max_size) * sizeof(Node*)); // null all new space
 717   }
 718   max_size = new_max;               // Record new max length
 719   // This assertion makes sure that Node::_max is wide enough to
 720   // represent the numerical value of new_max.
 721   assert(max_size > len, "int width of _max or _outmax is too small");
 722 }
 723 
 724 //------------------------------grow-------------------------------------------
 725 // Grow the input array, making space for more edges
 726 void Node::grow(uint len) {
 727   resize_array(_in, _max, len, true);
 728 }
 729 
 730 //-----------------------------out_grow----------------------------------------
 731 // Grow the input array, making space for more edges
 732 void Node::out_grow(uint len) {
 733   assert(!is_top(), "cannot grow a top node's out array");
 734   resize_array(_out, _outmax, len, false);
 735 }
 736 
 737 #ifdef ASSERT
 738 //------------------------------is_dead----------------------------------------
 739 bool Node::is_dead() const {
 740   // Mach and pinch point nodes may look like dead.
 741   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 742     return false;
 743   for( uint i = 0; i < _max; i++ )
 744     if( _in[i] != nullptr )
 745       return false;
 746   return true;
 747 }
 748 
 749 bool Node::is_not_dead(const Node* n) {
 750   return n == nullptr || !PhaseIterGVN::is_verify_def_use() || !(n->is_dead());
 751 }
 752 
 753 bool Node::is_reachable_from_root() const {
 754   ResourceMark rm;
 755   Unique_Node_List wq;
 756   wq.push((Node*)this);
 757   RootNode* root = Compile::current()->root();
 758   for (uint i = 0; i < wq.size(); i++) {
 759     Node* m = wq.at(i);
 760     if (m == root) {
 761       return true;
 762     }
 763     for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
 764       Node* u = m->fast_out(j);
 765       wq.push(u);
 766     }
 767   }
 768   return false;
 769 }
 770 #endif
 771 
 772 //------------------------------is_unreachable---------------------------------
 773 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 774   assert(!is_Mach(), "doesn't work with MachNodes");
 775   return outcnt() == 0 || igvn.type(this) == Type::TOP || (in(0) != nullptr && in(0)->is_top());
 776 }
 777 
 778 //------------------------------add_req----------------------------------------
 779 // Add a new required input at the end
 780 void Node::add_req( Node *n ) {
 781   assert( is_not_dead(n), "can not use dead node");
 782 
 783   // Look to see if I can move precedence down one without reallocating
 784   if( (_cnt >= _max) || (in(_max-1) != nullptr) )
 785     grow( _max+1 );
 786 
 787   // Find a precedence edge to move
 788   if( in(_cnt) != nullptr ) {   // Next precedence edge is busy?
 789     uint i;
 790     for( i=_cnt; i<_max; i++ )
 791       if( in(i) == nullptr )    // Find the null at end of prec edge list
 792         break;                  // There must be one, since we grew the array
 793     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 794   }
 795   _in[_cnt++] = n;            // Stuff over old prec edge
 796   if (n != nullptr) n->add_out((Node *)this);
 797   Compile::current()->record_modified_node(this);
 798 }
 799 
 800 //---------------------------add_req_batch-------------------------------------
 801 // Add a new required input at the end
 802 void Node::add_req_batch( Node *n, uint m ) {
 803   assert( is_not_dead(n), "can not use dead node");
 804   // check various edge cases
 805   if ((int)m <= 1) {
 806     assert((int)m >= 0, "oob");
 807     if (m != 0)  add_req(n);
 808     return;
 809   }
 810 
 811   // Look to see if I can move precedence down one without reallocating
 812   if( (_cnt+m) > _max || _in[_max-m] )
 813     grow( _max+m );
 814 
 815   // Find a precedence edge to move
 816   if( _in[_cnt] != nullptr ) {  // Next precedence edge is busy?
 817     uint i;
 818     for( i=_cnt; i<_max; i++ )
 819       if( _in[i] == nullptr )   // Find the null at end of prec edge list
 820         break;                  // There must be one, since we grew the array
 821     // Slide all the precs over by m positions (assume #prec << m).
 822     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 823   }
 824 
 825   // Stuff over the old prec edges
 826   for(uint i=0; i<m; i++ ) {
 827     _in[_cnt++] = n;
 828   }
 829 
 830   // Insert multiple out edges on the node.
 831   if (n != nullptr && !n->is_top()) {
 832     for(uint i=0; i<m; i++ ) {
 833       n->add_out((Node *)this);
 834     }
 835   }
 836   Compile::current()->record_modified_node(this);
 837 }
 838 
 839 //------------------------------del_req----------------------------------------
 840 // Delete the required edge and compact the edge array
 841 void Node::del_req( uint idx ) {
 842   assert( idx < _cnt, "oob");
 843   assert( !VerifyHashTableKeys || _hash_lock == 0,
 844           "remove node from hash table before modifying it");
 845   // First remove corresponding def-use edge
 846   Node *n = in(idx);
 847   if (n != nullptr) n->del_out((Node *)this);
 848   _in[idx] = in(--_cnt); // Compact the array
 849   // Avoid spec violation: Gap in prec edges.
 850   close_prec_gap_at(_cnt);
 851   Compile::current()->record_modified_node(this);
 852 }
 853 
 854 //------------------------------del_req_ordered--------------------------------
 855 // Delete the required edge and compact the edge array with preserved order
 856 void Node::del_req_ordered( uint idx ) {
 857   assert( idx < _cnt, "oob");
 858   assert( !VerifyHashTableKeys || _hash_lock == 0,
 859           "remove node from hash table before modifying it");
 860   // First remove corresponding def-use edge
 861   Node *n = in(idx);
 862   if (n != nullptr) n->del_out((Node *)this);
 863   if (idx < --_cnt) {    // Not last edge ?
 864     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
 865   }
 866   // Avoid spec violation: Gap in prec edges.
 867   close_prec_gap_at(_cnt);
 868   Compile::current()->record_modified_node(this);
 869 }
 870 
 871 //------------------------------ins_req----------------------------------------
 872 // Insert a new required input at the end
 873 void Node::ins_req( uint idx, Node *n ) {
 874   assert( is_not_dead(n), "can not use dead node");
 875   add_req(nullptr);                // Make space
 876   assert( idx < _max, "Must have allocated enough space");
 877   // Slide over
 878   if(_cnt-idx-1 > 0) {
 879     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 880   }
 881   _in[idx] = n;                            // Stuff over old required edge
 882   if (n != nullptr) n->add_out((Node *)this); // Add reciprocal def-use edge
 883   Compile::current()->record_modified_node(this);
 884 }
 885 
 886 //-----------------------------find_edge---------------------------------------
 887 int Node::find_edge(Node* n) {
 888   for (uint i = 0; i < len(); i++) {
 889     if (_in[i] == n)  return i;
 890   }
 891   return -1;
 892 }
 893 
 894 //----------------------------replace_edge-------------------------------------
 895 int Node::replace_edge(Node* old, Node* neww, PhaseGVN* gvn) {
 896   if (old == neww)  return 0;  // nothing to do
 897   uint nrep = 0;
 898   for (uint i = 0; i < len(); i++) {
 899     if (in(i) == old) {
 900       if (i < req()) {
 901         if (gvn != nullptr) {
 902           set_req_X(i, neww, gvn);
 903         } else {
 904           set_req(i, neww);
 905         }
 906       } else {
 907         assert(gvn == nullptr || gvn->is_IterGVN() == nullptr, "no support for igvn here");
 908         assert(find_prec_edge(neww) == -1, "spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx);
 909         set_prec(i, neww);
 910       }
 911       nrep++;
 912     }
 913   }
 914   return nrep;
 915 }
 916 
 917 /**
 918  * Replace input edges in the range pointing to 'old' node.
 919  */
 920 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end, PhaseGVN* gvn) {
 921   if (old == neww)  return 0;  // nothing to do
 922   uint nrep = 0;
 923   for (int i = start; i < end; i++) {
 924     if (in(i) == old) {
 925       set_req_X(i, neww, gvn);
 926       nrep++;
 927     }
 928   }
 929   return nrep;
 930 }
 931 
 932 //-------------------------disconnect_inputs-----------------------------------
 933 // null out all inputs to eliminate incoming Def-Use edges.
 934 void Node::disconnect_inputs(Compile* C) {
 935   // the layout of Node::_in
 936   // r: a required input, null is allowed
 937   // p: a precedence, null values are all at the end
 938   // -----------------------------------
 939   // |r|...|r|p|...|p|null|...|null|
 940   //         |                     |
 941   //         req()                 len()
 942   // -----------------------------------
 943   for (uint i = 0; i < req(); ++i) {
 944     if (in(i) != nullptr) {
 945       set_req(i, nullptr);
 946     }
 947   }
 948 
 949   // Remove precedence edges if any exist
 950   // Note: Safepoints may have precedence edges, even during parsing
 951   for (uint i = len(); i > req(); ) {
 952     rm_prec(--i);  // no-op if _in[i] is null
 953   }
 954 
 955 #ifdef ASSERT
 956   // sanity check
 957   for (uint i = 0; i < len(); ++i) {
 958     assert(_in[i] == nullptr, "disconnect_inputs() failed!");
 959   }
 960 #endif
 961 
 962   // Node::destruct requires all out edges be deleted first
 963   // DEBUG_ONLY(destruct();)   // no reuse benefit expected
 964   C->record_dead_node(_idx);
 965 }
 966 
 967 //-----------------------------uncast---------------------------------------
 968 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 969 // Strip away casting.  (It is depth-limited.)
 970 // Optionally, keep casts with dependencies.
 971 Node* Node::uncast(bool keep_deps) const {
 972   // Should be inline:
 973   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 974   if (is_ConstraintCast()) {
 975     return uncast_helper(this, keep_deps);
 976   } else {
 977     return (Node*) this;
 978   }
 979 }
 980 
 981 // Find out of current node that matches opcode.
 982 Node* Node::find_out_with(int opcode) {
 983   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 984     Node* use = fast_out(i);
 985     if (use->Opcode() == opcode) {
 986       return use;
 987     }
 988   }
 989   return nullptr;
 990 }
 991 
 992 // Return true if the current node has an out that matches opcode.
 993 bool Node::has_out_with(int opcode) {
 994   return (find_out_with(opcode) != nullptr);
 995 }
 996 
 997 // Return true if the current node has an out that matches any of the opcodes.
 998 bool Node::has_out_with(int opcode1, int opcode2, int opcode3, int opcode4) {
 999   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
1000       int opcode = fast_out(i)->Opcode();
1001       if (opcode == opcode1 || opcode == opcode2 || opcode == opcode3 || opcode == opcode4) {
1002         return true;
1003       }
1004   }
1005   return false;
1006 }
1007 
1008 
1009 //---------------------------uncast_helper-------------------------------------
1010 Node* Node::uncast_helper(const Node* p, bool keep_deps) {
1011 #ifdef ASSERT
1012   // If we end up traversing more nodes than we actually have,
1013   // it is definitely an infinite loop.
1014   uint max_depth = Compile::current()->unique();
1015   uint depth_count = 0;
1016   const Node* orig_p = p;
1017 #endif
1018 
1019   while (true) {
1020 #ifdef ASSERT
1021     if (depth_count++ >= max_depth) {
1022       orig_p->dump(4);
1023       if (p != orig_p) {
1024         p->dump(1);
1025       }
1026       fatal("infinite loop in Node::uncast_helper");
1027     }
1028 #endif
1029     if (p == nullptr || p->req() != 2) {
1030       break;
1031     } else if (p->is_ConstraintCast()) {
1032       if (keep_deps && p->as_ConstraintCast()->carry_dependency()) {
1033         break; // stop at casts with dependencies
1034       }
1035       p = p->in(1);
1036     } else {
1037       break;
1038     }
1039   }
1040   return (Node*) p;
1041 }
1042 
1043 //------------------------------add_prec---------------------------------------
1044 // Add a new precedence input.  Precedence inputs are unordered, with
1045 // duplicates removed and nulls packed down at the end.
1046 void Node::add_prec( Node *n ) {
1047   assert( is_not_dead(n), "can not use dead node");
1048 
1049   // Check for null at end
1050   if( _cnt >= _max || in(_max-1) )
1051     grow( _max+1 );
1052 
1053   // Find a precedence edge to move
1054   uint i = _cnt;
1055   while( in(i) != nullptr ) {
1056     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
1057     i++;
1058   }
1059   _in[i] = n;                                   // Stuff prec edge over null
1060   if ( n != nullptr) n->add_out((Node *)this);  // Add mirror edge
1061 
1062 #ifdef ASSERT
1063   while ((++i)<_max) { assert(_in[i] == nullptr, "spec violation: Gap in prec edges (node %d)", _idx); }
1064 #endif
1065   Compile::current()->record_modified_node(this);
1066 }
1067 
1068 //------------------------------rm_prec----------------------------------------
1069 // Remove a precedence input.  Precedence inputs are unordered, with
1070 // duplicates removed and nulls packed down at the end.
1071 void Node::rm_prec( uint j ) {
1072   assert(j < _max, "oob: i=%d, _max=%d", j, _max);
1073   assert(j >= _cnt, "not a precedence edge");
1074   if (_in[j] == nullptr) return;   // Avoid spec violation: Gap in prec edges.
1075   _in[j]->del_out((Node *)this);
1076   close_prec_gap_at(j);
1077   Compile::current()->record_modified_node(this);
1078 }
1079 
1080 //------------------------------size_of----------------------------------------
1081 uint Node::size_of() const { return sizeof(*this); }
1082 
1083 //------------------------------ideal_reg--------------------------------------
1084 uint Node::ideal_reg() const { return 0; }
1085 
1086 //------------------------------jvms-------------------------------------------
1087 JVMState* Node::jvms() const { return nullptr; }
1088 
1089 #ifdef ASSERT
1090 //------------------------------jvms-------------------------------------------
1091 bool Node::verify_jvms(const JVMState* using_jvms) const {
1092   for (JVMState* jvms = this->jvms(); jvms != nullptr; jvms = jvms->caller()) {
1093     if (jvms == using_jvms)  return true;
1094   }
1095   return false;
1096 }
1097 
1098 //------------------------------init_NodeProperty------------------------------
1099 void Node::init_NodeProperty() {
1100   assert(_max_classes <= max_juint, "too many NodeProperty classes");
1101   assert(max_flags() <= max_juint, "too many NodeProperty flags");
1102 }
1103 
1104 //-----------------------------max_flags---------------------------------------
1105 juint Node::max_flags() {
1106   return (PD::_last_flag << 1) - 1; // allow flags combination
1107 }
1108 #endif
1109 
1110 //------------------------------format-----------------------------------------
1111 // Print as assembly
1112 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1113 //------------------------------emit-------------------------------------------
1114 // Emit bytes using C2_MacroAssembler
1115 void Node::emit(C2_MacroAssembler *masm, PhaseRegAlloc *ra_) const {}
1116 //------------------------------size-------------------------------------------
1117 // Size of instruction in bytes
1118 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1119 
1120 //------------------------------CFG Construction-------------------------------
1121 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1122 // Goto and Return.
1123 const Node *Node::is_block_proj() const { return nullptr; }
1124 
1125 // Minimum guaranteed type
1126 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1127 
1128 
1129 //------------------------------raise_bottom_type------------------------------
1130 // Get the worst-case Type output for this Node.
1131 void Node::raise_bottom_type(const Type* new_type) {
1132   if (is_Type()) {
1133     TypeNode *n = this->as_Type();
1134     if (VerifyAliases) {
1135       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1136     }
1137     n->set_type(new_type);
1138   } else if (is_Load()) {
1139     LoadNode *n = this->as_Load();
1140     if (VerifyAliases) {
1141       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1142     }
1143     n->set_type(new_type);
1144   }
1145 }
1146 
1147 //------------------------------Identity---------------------------------------
1148 // Return a node that the given node is equivalent to.
1149 Node* Node::Identity(PhaseGVN* phase) {
1150   return this;                  // Default to no identities
1151 }
1152 
1153 //------------------------------Value------------------------------------------
1154 // Compute a new Type for a node using the Type of the inputs.
1155 const Type* Node::Value(PhaseGVN* phase) const {
1156   return bottom_type();         // Default to worst-case Type
1157 }
1158 
1159 //------------------------------Ideal------------------------------------------
1160 //
1161 // 'Idealize' the graph rooted at this Node.
1162 //
1163 // In order to be efficient and flexible there are some subtle invariants
1164 // these Ideal calls need to hold.  Running with '-XX:VerifyIterativeGVN=1' checks
1165 // these invariants, although its too slow to have on by default.  If you are
1166 // hacking an Ideal call, be sure to test with '-XX:VerifyIterativeGVN=1'
1167 //
1168 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1169 // pointer.  If ANY change is made, it must return the root of the reshaped
1170 // graph - even if the root is the same Node.  Example: swapping the inputs
1171 // to an AddINode gives the same answer and same root, but you still have to
1172 // return the 'this' pointer instead of null.
1173 //
1174 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1175 // Identity call to return an old Node; basically if Identity can find
1176 // another Node have the Ideal call make no change and return null.
1177 // Example: AddINode::Ideal must check for add of zero; in this case it
1178 // returns null instead of doing any graph reshaping.
1179 //
1180 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1181 // sharing there may be other users of the old Nodes relying on their current
1182 // semantics.  Modifying them will break the other users.
1183 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1184 // "X+3" unchanged in case it is shared.
1185 //
1186 // If you modify the 'this' pointer's inputs, you should use
1187 // 'set_req'.  If you are making a new Node (either as the new root or
1188 // some new internal piece) you may use 'init_req' to set the initial
1189 // value.  You can make a new Node with either 'new' or 'clone'.  In
1190 // either case, def-use info is correctly maintained.
1191 //
1192 // Example: reshape "(X+3)+4" into "X+7":
1193 //    set_req(1, in(1)->in(1));
1194 //    set_req(2, phase->intcon(7));
1195 //    return this;
1196 // Example: reshape "X*4" into "X<<2"
1197 //    return new LShiftINode(in(1), phase->intcon(2));
1198 //
1199 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1200 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1201 //    Node *shift=phase->transform(new LShiftINode(in(1),phase->intcon(5)));
1202 //    return new AddINode(shift, in(1));
1203 //
1204 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1205 // These forms are faster than 'phase->transform(new ConNode())' and Do
1206 // The Right Thing with def-use info.
1207 //
1208 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1209 // graph uses the 'this' Node it must be the root.  If you want a Node with
1210 // the same Opcode as the 'this' pointer use 'clone'.
1211 //
1212 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1213   return nullptr;                  // Default to being Ideal already
1214 }
1215 
1216 // Some nodes have specific Ideal subgraph transformations only if they are
1217 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1218 // for the transformations to happen.
1219 bool Node::has_special_unique_user() const {
1220   assert(outcnt() == 1, "match only for unique out");
1221   Node* n = unique_out();
1222   int op  = Opcode();
1223   if (this->is_Store()) {
1224     // Condition for back-to-back stores folding.
1225     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1226   } else if ((this->is_Load() || this->is_DecodeN() || this->is_Phi()) && n->Opcode() == Op_MemBarAcquire) {
1227     // Condition for removing an unused LoadNode or DecodeNNode from the MemBarAcquire precedence input
1228     return true;
1229   } else if (this->is_Load() && n->is_Move()) {
1230     // Condition for MoveX2Y (LoadX mem) => LoadY mem
1231     return true;
1232   } else if (op == Op_AddL) {
1233     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1234     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1235   } else if (op == Op_SubI || op == Op_SubL) {
1236     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1237     return n->Opcode() == op && n->in(2) == this;
1238   } else if (is_If() && (n->is_IfFalse() || n->is_IfTrue())) {
1239     // See IfProjNode::Identity()
1240     return true;
1241   } else if ((is_IfFalse() || is_IfTrue()) && n->is_If()) {
1242     // See IfNode::fold_compares
1243     return true;
1244   } else if (n->Opcode() == Op_XorV || n->Opcode() == Op_XorVMask) {
1245     // Condition for XorVMask(VectorMaskCmp(x,y,cond), MaskAll(true)) ==> VectorMaskCmp(x,y,ncond)
1246     return true;
1247   } else {
1248     return false;
1249   }
1250 };
1251 
1252 //--------------------------find_exact_control---------------------------------
1253 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1254 Node* Node::find_exact_control(Node* ctrl) {
1255   if (ctrl == nullptr && this->is_Region())
1256     ctrl = this->as_Region()->is_copy();
1257 
1258   if (ctrl != nullptr && ctrl->is_CatchProj()) {
1259     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1260       ctrl = ctrl->in(0);
1261     if (ctrl != nullptr && !ctrl->is_top())
1262       ctrl = ctrl->in(0);
1263   }
1264 
1265   if (ctrl != nullptr && ctrl->is_Proj())
1266     ctrl = ctrl->in(0);
1267 
1268   return ctrl;
1269 }
1270 
1271 //--------------------------dominates------------------------------------------
1272 // Helper function for MemNode::all_controls_dominate().
1273 // Check if 'this' control node dominates or equal to 'sub' control node.
1274 // We already know that if any path back to Root or Start reaches 'this',
1275 // then all paths so, so this is a simple search for one example,
1276 // not an exhaustive search for a counterexample.
1277 Node::DomResult Node::dominates(Node* sub, Node_List &nlist) {
1278   assert(this->is_CFG(), "expecting control");
1279   assert(sub != nullptr && sub->is_CFG(), "expecting control");
1280 
1281   // detect dead cycle without regions
1282   int iterations_without_region_limit = DominatorSearchLimit;
1283 
1284   Node* orig_sub = sub;
1285   Node* dom      = this;
1286   bool  met_dom  = false;
1287   nlist.clear();
1288 
1289   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1290   // After seeing 'dom', continue up to Root or Start.
1291   // If we hit a region (backward split point), it may be a loop head.
1292   // Keep going through one of the region's inputs.  If we reach the
1293   // same region again, go through a different input.  Eventually we
1294   // will either exit through the loop head, or give up.
1295   // (If we get confused, break out and return a conservative 'false'.)
1296   while (sub != nullptr) {
1297     if (sub->is_top()) {
1298       // Conservative answer for dead code.
1299       return DomResult::EncounteredDeadCode;
1300     }
1301     if (sub == dom) {
1302       if (nlist.size() == 0) {
1303         // No Region nodes except loops were visited before and the EntryControl
1304         // path was taken for loops: it did not walk in a cycle.
1305         return DomResult::Dominate;
1306       } else if (met_dom) {
1307         break;          // already met before: walk in a cycle
1308       } else {
1309         // Region nodes were visited. Continue walk up to Start or Root
1310         // to make sure that it did not walk in a cycle.
1311         met_dom = true; // first time meet
1312         iterations_without_region_limit = DominatorSearchLimit; // Reset
1313      }
1314     }
1315     if (sub->is_Start() || sub->is_Root()) {
1316       // Success if we met 'dom' along a path to Start or Root.
1317       // We assume there are no alternative paths that avoid 'dom'.
1318       // (This assumption is up to the caller to ensure!)
1319       return met_dom ? DomResult::Dominate : DomResult::NotDominate;
1320     }
1321     Node* up = sub->in(0);
1322     // Normalize simple pass-through regions and projections:
1323     up = sub->find_exact_control(up);
1324     // If sub == up, we found a self-loop.  Try to push past it.
1325     if (sub == up && sub->is_Loop()) {
1326       // Take loop entry path on the way up to 'dom'.
1327       up = sub->in(1); // in(LoopNode::EntryControl);
1328     } else if (sub == up && sub->is_Region() && sub->req() == 2) {
1329       // Take in(1) path on the way up to 'dom' for regions with only one input
1330       up = sub->in(1);
1331     } else if (sub == up && sub->is_Region()) {
1332       // Try both paths for Regions with 2 input paths (it may be a loop head).
1333       // It could give conservative 'false' answer without information
1334       // which region's input is the entry path.
1335       iterations_without_region_limit = DominatorSearchLimit; // Reset
1336 
1337       bool region_was_visited_before = false;
1338       // Was this Region node visited before?
1339       // If so, we have reached it because we accidentally took a
1340       // loop-back edge from 'sub' back into the body of the loop,
1341       // and worked our way up again to the loop header 'sub'.
1342       // So, take the first unexplored path on the way up to 'dom'.
1343       for (int j = nlist.size() - 1; j >= 0; j--) {
1344         intptr_t ni = (intptr_t)nlist.at(j);
1345         Node* visited = (Node*)(ni & ~1);
1346         bool  visited_twice_already = ((ni & 1) != 0);
1347         if (visited == sub) {
1348           if (visited_twice_already) {
1349             // Visited 2 paths, but still stuck in loop body.  Give up.
1350             return DomResult::NotDominate;
1351           }
1352           // The Region node was visited before only once.
1353           // (We will repush with the low bit set, below.)
1354           nlist.remove(j);
1355           // We will find a new edge and re-insert.
1356           region_was_visited_before = true;
1357           break;
1358         }
1359       }
1360 
1361       // Find an incoming edge which has not been seen yet; walk through it.
1362       assert(up == sub, "");
1363       uint skip = region_was_visited_before ? 1 : 0;
1364       for (uint i = 1; i < sub->req(); i++) {
1365         Node* in = sub->in(i);
1366         if (in != nullptr && !in->is_top() && in != sub) {
1367           if (skip == 0) {
1368             up = in;
1369             break;
1370           }
1371           --skip;               // skip this nontrivial input
1372         }
1373       }
1374 
1375       // Set 0 bit to indicate that both paths were taken.
1376       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1377     }
1378 
1379     if (up == sub) {
1380       break;    // some kind of tight cycle
1381     }
1382     if (up == orig_sub && met_dom) {
1383       // returned back after visiting 'dom'
1384       break;    // some kind of cycle
1385     }
1386     if (--iterations_without_region_limit < 0) {
1387       break;    // dead cycle
1388     }
1389     sub = up;
1390   }
1391 
1392   // Did not meet Root or Start node in pred. chain.
1393   return DomResult::NotDominate;
1394 }
1395 
1396 //------------------------------remove_dead_region-----------------------------
1397 // This control node is dead.  Follow the subgraph below it making everything
1398 // using it dead as well.  This will happen normally via the usual IterGVN
1399 // worklist but this call is more efficient.  Do not update use-def info
1400 // inside the dead region, just at the borders.
1401 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1402   // Con's are a popular node to re-hit in the hash table again.
1403   if( dead->is_Con() ) return;
1404 
1405   ResourceMark rm;
1406   Node_List nstack;
1407   VectorSet dead_set; // notify uses only once
1408 
1409   Node *top = igvn->C->top();
1410   nstack.push(dead);
1411   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1412 
1413   while (nstack.size() > 0) {
1414     dead = nstack.pop();
1415     if (!dead_set.test_set(dead->_idx)) {
1416       // If dead has any live uses, those are now still attached. Notify them before we lose them.
1417       igvn->add_users_to_worklist(dead);
1418     }
1419     if (dead->Opcode() == Op_SafePoint) {
1420       dead->as_SafePoint()->disconnect_from_root(igvn);
1421     }
1422     if (dead->outcnt() > 0) {
1423       // Keep dead node on stack until all uses are processed.
1424       nstack.push(dead);
1425       // For all Users of the Dead...    ;-)
1426       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1427         Node* use = dead->last_out(k);
1428         igvn->hash_delete(use);       // Yank from hash table prior to mod
1429         if (use->in(0) == dead) {     // Found another dead node
1430           assert (!use->is_Con(), "Control for Con node should be Root node.");
1431           use->set_req(0, top);       // Cut dead edge to prevent processing
1432           nstack.push(use);           // the dead node again.
1433         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1434                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1435                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1436           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1437           use->set_req(0, top);       // Cut self edge
1438           nstack.push(use);
1439         } else {                      // Else found a not-dead user
1440           // Dead if all inputs are top or null
1441           bool dead_use = !use->is_Root(); // Keep empty graph alive
1442           for (uint j = 1; j < use->req(); j++) {
1443             Node* in = use->in(j);
1444             if (in == dead) {         // Turn all dead inputs into TOP
1445               use->set_req(j, top);
1446             } else if (in != nullptr && !in->is_top()) {
1447               dead_use = false;
1448             }
1449           }
1450           if (dead_use) {
1451             if (use->is_Region()) {
1452               use->set_req(0, top);   // Cut self edge
1453             }
1454             nstack.push(use);
1455           } else {
1456             igvn->_worklist.push(use);
1457           }
1458         }
1459         // Refresh the iterator, since any number of kills might have happened.
1460         k = dead->last_outs(kmin);
1461       }
1462     } else { // (dead->outcnt() == 0)
1463       // Done with outputs.
1464       igvn->hash_delete(dead);
1465       igvn->_worklist.remove(dead);
1466       igvn->set_type(dead, Type::TOP);
1467       // Kill all inputs to the dead guy
1468       for (uint i=0; i < dead->req(); i++) {
1469         Node *n = dead->in(i);      // Get input to dead guy
1470         if (n != nullptr && !n->is_top()) { // Input is valid?
1471           dead->set_req(i, top);    // Smash input away
1472           if (n->outcnt() == 0) {   // Input also goes dead?
1473             if (!n->is_Con())
1474               nstack.push(n);       // Clear it out as well
1475           } else if (n->outcnt() == 1 &&
1476                      n->has_special_unique_user()) {
1477             igvn->add_users_to_worklist( n );
1478           } else if (n->outcnt() <= 2 && n->is_Store()) {
1479             // Push store's uses on worklist to enable folding optimization for
1480             // store/store and store/load to the same address.
1481             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1482             // and remove_globally_dead_node().
1483             igvn->add_users_to_worklist( n );
1484           } else if (dead->is_data_proj_of_pure_function(n)) {
1485             igvn->_worklist.push(n);
1486           } else {
1487             BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, n);
1488           }
1489         }
1490       }
1491       igvn->C->remove_useless_node(dead);
1492     } // (dead->outcnt() == 0)
1493   }   // while (nstack.size() > 0) for outputs
1494   return;
1495 }
1496 
1497 //------------------------------remove_dead_region-----------------------------
1498 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1499   Node *n = in(0);
1500   if( !n ) return false;
1501   // Lost control into this guy?  I.e., it became unreachable?
1502   // Aggressively kill all unreachable code.
1503   if (can_reshape && n->is_top()) {
1504     kill_dead_code(this, phase->is_IterGVN());
1505     return false; // Node is dead.
1506   }
1507 
1508   if( n->is_Region() && n->as_Region()->is_copy() ) {
1509     Node *m = n->nonnull_req();
1510     set_req(0, m);
1511     return true;
1512   }
1513   return false;
1514 }
1515 
1516 //------------------------------hash-------------------------------------------
1517 // Hash function over Nodes.
1518 uint Node::hash() const {
1519   uint sum = 0;
1520   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1521     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded nulls
1522   return (sum>>2) + _cnt + Opcode();
1523 }
1524 
1525 //------------------------------cmp--------------------------------------------
1526 // Compare special parts of simple Nodes
1527 bool Node::cmp( const Node &n ) const {
1528   return true;                  // Must be same
1529 }
1530 
1531 //------------------------------rematerialize-----------------------------------
1532 // Should we clone rather than spill this instruction?
1533 bool Node::rematerialize() const {
1534   if ( is_Mach() )
1535     return this->as_Mach()->rematerialize();
1536   else
1537     return (_flags & Flag_rematerialize) != 0;
1538 }
1539 
1540 //------------------------------needs_anti_dependence_check---------------------
1541 // Nodes which use memory without consuming it, hence need antidependences.
1542 bool Node::needs_anti_dependence_check() const {
1543   if (req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0) {
1544     return false;
1545   }
1546   return in(1)->bottom_type()->has_memory();
1547 }
1548 
1549 // Get an integer constant from a ConNode (or CastIINode).
1550 // Return a default value if there is no apparent constant here.
1551 const TypeInt* Node::find_int_type() const {
1552   if (this->is_Type()) {
1553     return this->as_Type()->type()->isa_int();
1554   } else if (this->is_Con()) {
1555     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1556     return this->bottom_type()->isa_int();
1557   }
1558   return nullptr;
1559 }
1560 
1561 const TypeInteger* Node::find_integer_type(BasicType bt) const {
1562   if (this->is_Type()) {
1563     return this->as_Type()->type()->isa_integer(bt);
1564   } else if (this->is_Con()) {
1565     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1566     return this->bottom_type()->isa_integer(bt);
1567   }
1568   return nullptr;
1569 }
1570 
1571 // Get a pointer constant from a ConstNode.
1572 // Returns the constant if it is a pointer ConstNode
1573 intptr_t Node::get_ptr() const {
1574   assert( Opcode() == Op_ConP, "" );
1575   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1576 }
1577 
1578 // Get a narrow oop constant from a ConNNode.
1579 intptr_t Node::get_narrowcon() const {
1580   assert( Opcode() == Op_ConN, "" );
1581   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1582 }
1583 
1584 // Get a long constant from a ConNode.
1585 // Return a default value if there is no apparent constant here.
1586 const TypeLong* Node::find_long_type() const {
1587   if (this->is_Type()) {
1588     return this->as_Type()->type()->isa_long();
1589   } else if (this->is_Con()) {
1590     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1591     return this->bottom_type()->isa_long();
1592   }
1593   return nullptr;
1594 }
1595 
1596 
1597 /**
1598  * Return a ptr type for nodes which should have it.
1599  */
1600 const TypePtr* Node::get_ptr_type() const {
1601   const TypePtr* tp = this->bottom_type()->make_ptr();
1602 #ifdef ASSERT
1603   if (tp == nullptr) {
1604     this->dump(1);
1605     assert((tp != nullptr), "unexpected node type");
1606   }
1607 #endif
1608   return tp;
1609 }
1610 
1611 // Get a double constant from a ConstNode.
1612 // Returns the constant if it is a double ConstNode
1613 jdouble Node::getd() const {
1614   assert( Opcode() == Op_ConD, "" );
1615   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1616 }
1617 
1618 // Get a float constant from a ConstNode.
1619 // Returns the constant if it is a float ConstNode
1620 jfloat Node::getf() const {
1621   assert( Opcode() == Op_ConF, "" );
1622   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1623 }
1624 
1625 // Get a half float constant from a ConstNode.
1626 // Returns the constant if it is a float ConstNode
1627 jshort Node::geth() const {
1628   assert( Opcode() == Op_ConH, "" );
1629   return ((ConHNode*)this)->type()->is_half_float_constant()->geth();
1630 }
1631 
1632 #ifndef PRODUCT
1633 
1634 // Call this from debugger:
1635 Node* old_root() {
1636   Matcher* matcher = Compile::current()->matcher();
1637   if (matcher != nullptr) {
1638     Node* new_root = Compile::current()->root();
1639     Node* old_root = matcher->find_old_node(new_root);
1640     if (old_root != nullptr) {
1641       return old_root;
1642     }
1643   }
1644   tty->print("old_root: not found.\n");
1645   return nullptr;
1646 }
1647 
1648 // BFS traverse all reachable nodes from start, call callback on them
1649 template <typename Callback>
1650 void visit_nodes(Node* start, Callback callback, bool traverse_output, bool only_ctrl) {
1651   Unique_Mixed_Node_List worklist;
1652   worklist.add(start);
1653   for (uint i = 0; i < worklist.size(); i++) {
1654     Node* n = worklist[i];
1655     callback(n);
1656     for (uint i = 0; i < n->len(); i++) {
1657       if (!only_ctrl || n->is_Region() || (n->Opcode() == Op_Root) || (i == TypeFunc::Control)) {
1658         // If only_ctrl is set: Add regions, the root node, or control inputs only
1659         worklist.add(n->in(i));
1660       }
1661     }
1662     if (traverse_output && !only_ctrl) {
1663       for (uint i = 0; i < n->outcnt(); i++) {
1664         worklist.add(n->raw_out(i));
1665       }
1666     }
1667   }
1668 }
1669 
1670 // BFS traverse from start, return node with idx
1671 static Node* find_node_by_idx(Node* start, uint idx, bool traverse_output, bool only_ctrl) {
1672   ResourceMark rm;
1673   Node* result = nullptr;
1674   auto callback = [&] (Node* n) {
1675     if (n->_idx == idx) {
1676       if (result != nullptr) {
1677         tty->print("find_node_by_idx: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1678           (uintptr_t)result, (uintptr_t)n, idx);
1679       }
1680       result = n;
1681     }
1682   };
1683   visit_nodes(start, callback, traverse_output, only_ctrl);
1684   return result;
1685 }
1686 
1687 static int node_idx_cmp(const Node** n1, const Node** n2) {
1688   return (*n1)->_idx - (*n2)->_idx;
1689 }
1690 
1691 static void find_nodes_by_name(Node* start, const char* name) {
1692   ResourceMark rm;
1693   GrowableArray<const Node*> ns;
1694   auto callback = [&] (const Node* n) {
1695     if (StringUtils::is_star_match(name, n->Name())) {
1696       ns.push(n);
1697     }
1698   };
1699   visit_nodes(start, callback, true, false);
1700   ns.sort(node_idx_cmp);
1701   for (int i = 0; i < ns.length(); i++) {
1702     ns.at(i)->dump();
1703   }
1704 }
1705 
1706 static void find_nodes_by_dump(Node* start, const char* pattern) {
1707   ResourceMark rm;
1708   GrowableArray<const Node*> ns;
1709   auto callback = [&] (const Node* n) {
1710     stringStream stream;
1711     n->dump("", false, &stream);
1712     if (StringUtils::is_star_match(pattern, stream.base())) {
1713       ns.push(n);
1714     }
1715   };
1716   visit_nodes(start, callback, true, false);
1717   ns.sort(node_idx_cmp);
1718   for (int i = 0; i < ns.length(); i++) {
1719     ns.at(i)->dump();
1720   }
1721 }
1722 
1723 // call from debugger: find node with name pattern in new/current graph
1724 // name can contain "*" in match pattern to match any characters
1725 // the matching is case insensitive
1726 void find_nodes_by_name(const char* name) {
1727   Node* root = Compile::current()->root();
1728   find_nodes_by_name(root, name);
1729 }
1730 
1731 // call from debugger: find node with name pattern in old graph
1732 // name can contain "*" in match pattern to match any characters
1733 // the matching is case insensitive
1734 void find_old_nodes_by_name(const char* name) {
1735   Node* root = old_root();
1736   find_nodes_by_name(root, name);
1737 }
1738 
1739 // call from debugger: find node with dump pattern in new/current graph
1740 // can contain "*" in match pattern to match any characters
1741 // the matching is case insensitive
1742 void find_nodes_by_dump(const char* pattern) {
1743   Node* root = Compile::current()->root();
1744   find_nodes_by_dump(root, pattern);
1745 }
1746 
1747 // call from debugger: find node with name pattern in old graph
1748 // can contain "*" in match pattern to match any characters
1749 // the matching is case insensitive
1750 void find_old_nodes_by_dump(const char* pattern) {
1751   Node* root = old_root();
1752   find_nodes_by_dump(root, pattern);
1753 }
1754 
1755 // Call this from debugger, search in same graph as n:
1756 Node* find_node(Node* n, const int idx) {
1757   return n->find(idx);
1758 }
1759 
1760 // Call this from debugger, search in new nodes:
1761 Node* find_node(const int idx) {
1762   return Compile::current()->root()->find(idx);
1763 }
1764 
1765 // Call this from debugger, search in old nodes:
1766 Node* find_old_node(const int idx) {
1767   Node* root = old_root();
1768   return (root == nullptr) ? nullptr : root->find(idx);
1769 }
1770 
1771 // Call this from debugger, search in same graph as n:
1772 Node* find_ctrl(Node* n, const int idx) {
1773   return n->find_ctrl(idx);
1774 }
1775 
1776 // Call this from debugger, search in new nodes:
1777 Node* find_ctrl(const int idx) {
1778   return Compile::current()->root()->find_ctrl(idx);
1779 }
1780 
1781 // Call this from debugger, search in old nodes:
1782 Node* find_old_ctrl(const int idx) {
1783   Node* root = old_root();
1784   return (root == nullptr) ? nullptr : root->find_ctrl(idx);
1785 }
1786 
1787 //------------------------------find_ctrl--------------------------------------
1788 // Find an ancestor to this node in the control history with given _idx
1789 Node* Node::find_ctrl(int idx) {
1790   return find(idx, true);
1791 }
1792 
1793 //------------------------------find-------------------------------------------
1794 // Tries to find the node with the index |idx| starting from this node. If idx is negative,
1795 // the search also includes forward (out) edges. Returns null if not found.
1796 // If only_ctrl is set, the search will only be done on control nodes. Returns null if
1797 // not found or if the node to be found is not a control node (search will not find it).
1798 Node* Node::find(const int idx, bool only_ctrl) {
1799   ResourceMark rm;
1800   return find_node_by_idx(this, abs(idx), (idx < 0), only_ctrl);
1801 }
1802 
1803 class PrintBFS {
1804 public:
1805   PrintBFS(const Node* start, const int max_distance, const Node* target, const char* options, outputStream* st, const frame* fr)
1806     : _start(start), _max_distance(max_distance), _target(target), _options(options), _output(st), _frame(fr),
1807     _dcc(this), _info_uid(cmpkey, hashkey) {}
1808 
1809   void run();
1810 private:
1811   // pipeline steps
1812   bool configure();
1813   void collect();
1814   void select();
1815   void select_all();
1816   void select_all_paths();
1817   void select_shortest_path();
1818   void sort();
1819   void print();
1820 
1821   // inputs
1822   const Node* _start;
1823   const int _max_distance;
1824   const Node* _target;
1825   const char* _options;
1826   outputStream* _output;
1827   const frame* _frame;
1828 
1829   // options
1830   bool _traverse_inputs = false;
1831   bool _traverse_outputs = false;
1832   struct Filter {
1833     bool _control = false;
1834     bool _memory = false;
1835     bool _data = false;
1836     bool _mixed = false;
1837     bool _other = false;
1838     bool is_empty() const {
1839       return !(_control || _memory || _data || _mixed || _other);
1840     }
1841     void set_all() {
1842       _control = true;
1843       _memory = true;
1844       _data = true;
1845       _mixed = true;
1846       _other = true;
1847     }
1848     // Check if the filter accepts the node. Go by the type categories, but also all CFG nodes
1849     // are considered to have control.
1850     bool accepts(const Node* n) {
1851       const Type* t = n->bottom_type();
1852       return ( _data    &&  t->has_category(Type::Category::Data)                    ) ||
1853              ( _memory  &&  t->has_category(Type::Category::Memory)                  ) ||
1854              ( _mixed   &&  t->has_category(Type::Category::Mixed)                   ) ||
1855              ( _control && (t->has_category(Type::Category::Control) || n->is_CFG()) ) ||
1856              ( _other   &&  t->has_category(Type::Category::Other)                   );
1857     }
1858   };
1859   Filter _filter_visit;
1860   Filter _filter_boundary;
1861   bool _sort_idx = false;
1862   bool _all_paths = false;
1863   bool _use_color = false;
1864   bool _print_blocks = false;
1865   bool _print_old = false;
1866   bool _dump_only = false;
1867   bool _print_igv = false;
1868 
1869   void print_options_help(bool print_examples);
1870   bool parse_options();
1871 
1872 public:
1873   class DumpConfigColored : public Node::DumpConfig {
1874   public:
1875     DumpConfigColored(PrintBFS* bfs) : _bfs(bfs) {};
1876     virtual void pre_dump(outputStream* st, const Node* n);
1877     virtual void post_dump(outputStream* st);
1878   private:
1879     PrintBFS* _bfs;
1880   };
1881 private:
1882   DumpConfigColored _dcc;
1883 
1884   // node info
1885   static Node* old_node(const Node* n); // mach node -> prior IR node
1886   void print_node_idx(const Node* n);
1887   void print_block_id(const Block* b);
1888   void print_node_block(const Node* n); // _pre_order, head idx, _idom, _dom_depth
1889 
1890   // traversal data structures
1891   GrowableArray<const Node*> _worklist; // BFS queue
1892   void maybe_traverse(const Node* src, const Node* dst);
1893 
1894   // node info annotation
1895   class Info {
1896   public:
1897     Info() : Info(nullptr, 0) {};
1898     Info(const Node* node, int distance)
1899       : _node(node), _distance_from_start(distance) {};
1900     const Node* node() const { return _node; };
1901     int distance() const { return _distance_from_start; };
1902     int distance_from_target() const { return _distance_from_target; }
1903     void set_distance_from_target(int d) { _distance_from_target = d; }
1904     GrowableArray<const Node*> edge_bwd; // pointing toward _start
1905     bool is_marked() const { return _mark; } // marked to keep during select
1906     void set_mark() { _mark = true; }
1907   private:
1908     const Node* _node;
1909     int _distance_from_start; // distance from _start
1910     int _distance_from_target = 0; // distance from _target if _all_paths
1911     bool _mark = false;
1912   };
1913   Dict _info_uid;            // Node -> uid
1914   GrowableArray<Info> _info; // uid  -> info
1915 
1916   Info* find_info(const Node* n) {
1917     size_t uid = (size_t)_info_uid[n];
1918     if (uid == 0) {
1919       return nullptr;
1920     }
1921     return &_info.at((int)uid);
1922   }
1923 
1924   void make_info(const Node* node, const int distance) {
1925     assert(find_info(node) == nullptr, "node does not yet have info");
1926     size_t uid = _info.length() + 1;
1927     _info_uid.Insert((void*)node, (void*)uid);
1928     _info.at_put_grow((int)uid, Info(node, distance));
1929     assert(find_info(node)->node() == node, "stored correct node");
1930   };
1931 
1932   // filled by sort, printed by print
1933   GrowableArray<const Node*> _print_list;
1934 
1935   // print header + node table
1936   void print_header() const;
1937   void print_node(const Node* n);
1938 };
1939 
1940 void PrintBFS::run() {
1941   if (!configure()) {
1942     return;
1943   }
1944   collect();
1945   select();
1946   sort();
1947   print();
1948 }
1949 
1950 // set up configuration for BFS and print
1951 bool PrintBFS::configure() {
1952   if (_max_distance < 0) {
1953     _output->print_cr("dump_bfs: max_distance must be non-negative!");
1954     return false;
1955   }
1956   return parse_options();
1957 }
1958 
1959 // BFS traverse according to configuration, fill worklist and info
1960 void PrintBFS::collect() {
1961   maybe_traverse(_start, _start);
1962   int pos = 0;
1963   while (pos < _worklist.length()) {
1964     const Node* n = _worklist.at(pos++); // next node to traverse
1965     Info* info = find_info(n);
1966     if (!_filter_visit.accepts(n) && n != _start) {
1967       continue; // we hit boundary, do not traverse further
1968     }
1969     if (n != _start && n->is_Root()) {
1970       continue; // traversing through root node would lead to unrelated nodes
1971     }
1972     if (_traverse_inputs && _max_distance > info->distance()) {
1973       for (uint i = 0; i < n->req(); i++) {
1974         maybe_traverse(n, n->in(i));
1975       }
1976     }
1977     if (_traverse_outputs && _max_distance > info->distance()) {
1978       for (uint i = 0; i < n->outcnt(); i++) {
1979         maybe_traverse(n, n->raw_out(i));
1980       }
1981     }
1982   }
1983 }
1984 
1985 // go through work list, mark those that we want to print
1986 void PrintBFS::select() {
1987   if (_target == nullptr ) {
1988     select_all();
1989   } else {
1990     if (find_info(_target) == nullptr) {
1991       _output->print_cr("Could not find target in BFS.");
1992       return;
1993     }
1994     if (_all_paths) {
1995       select_all_paths();
1996     } else {
1997       select_shortest_path();
1998     }
1999   }
2000 }
2001 
2002 // take all nodes from BFS
2003 void PrintBFS::select_all() {
2004   for (int i = 0; i < _worklist.length(); i++) {
2005     const Node* n = _worklist.at(i);
2006     Info* info = find_info(n);
2007     info->set_mark();
2008   }
2009 }
2010 
2011 // traverse backward from target, along edges found in BFS
2012 void PrintBFS::select_all_paths() {
2013   int pos = 0;
2014   GrowableArray<const Node*> backtrace;
2015   // start from target
2016   backtrace.push(_target);
2017   find_info(_target)->set_mark();
2018   // traverse backward
2019   while (pos < backtrace.length()) {
2020     const Node* n = backtrace.at(pos++);
2021     Info* info = find_info(n);
2022     for (int i = 0; i < info->edge_bwd.length(); i++) {
2023       // all backward edges
2024       const Node* back = info->edge_bwd.at(i);
2025       Info* back_info = find_info(back);
2026       if (!back_info->is_marked()) {
2027         // not yet found this on way back.
2028         back_info->set_distance_from_target(info->distance_from_target() + 1);
2029         if (back_info->distance_from_target() + back_info->distance() <= _max_distance) {
2030           // total distance is small enough
2031           back_info->set_mark();
2032           backtrace.push(back);
2033         }
2034       }
2035     }
2036   }
2037 }
2038 
2039 void PrintBFS::select_shortest_path() {
2040   const Node* current = _target;
2041   while (true) {
2042     Info* info = find_info(current);
2043     info->set_mark();
2044     if (current == _start) {
2045       break;
2046     }
2047     // first edge -> leads us one step closer to _start
2048     current = info->edge_bwd.at(0);
2049   }
2050 }
2051 
2052 // go through worklist in desired order, put the marked ones in print list
2053 void PrintBFS::sort() {
2054   if (_traverse_inputs && !_traverse_outputs) {
2055     // reverse order
2056     for (int i = _worklist.length() - 1; i >= 0; i--) {
2057       const Node* n = _worklist.at(i);
2058       Info* info = find_info(n);
2059       if (info->is_marked()) {
2060         _print_list.push(n);
2061       }
2062     }
2063   } else {
2064     // same order as worklist
2065     for (int i = 0; i < _worklist.length(); i++) {
2066       const Node* n = _worklist.at(i);
2067       Info* info = find_info(n);
2068       if (info->is_marked()) {
2069         _print_list.push(n);
2070       }
2071     }
2072   }
2073   if (_sort_idx) {
2074     _print_list.sort(node_idx_cmp);
2075   }
2076 }
2077 
2078 // go through printlist and print
2079 void PrintBFS::print() {
2080   if (_print_list.length() > 0 ) {
2081     print_header();
2082     for (int i = 0; i < _print_list.length(); i++) {
2083       const Node* n = _print_list.at(i);
2084       print_node(n);
2085     }
2086     if (_print_igv) {
2087       Compile* C = Compile::current();
2088       C->init_igv();
2089       C->igv_print_graph_to_network(nullptr, _print_list, _frame);
2090     }
2091   } else {
2092     _output->print_cr("No nodes to print.");
2093   }
2094 }
2095 
2096 void PrintBFS::print_options_help(bool print_examples) {
2097   _output->print_cr("Usage: node->dump_bfs(int max_distance, Node* target, char* options)");
2098   _output->print_cr("");
2099   _output->print_cr("Use cases:");
2100   _output->print_cr("  BFS traversal: no target required");
2101   _output->print_cr("  shortest path: set target");
2102   _output->print_cr("  all paths: set target and put 'A' in options");
2103   _output->print_cr("  detect loop: subcase of all paths, have start==target");
2104   _output->print_cr("");
2105   _output->print_cr("Arguments:");
2106   _output->print_cr("  this/start: staring point of BFS");
2107   _output->print_cr("  target:");
2108   _output->print_cr("    if null: simple BFS");
2109   _output->print_cr("    else: shortest path or all paths between this/start and target");
2110   _output->print_cr("  options:");
2111   _output->print_cr("    if null: same as \"cdmox@B\"");
2112   _output->print_cr("    else: use combination of following characters");
2113   _output->print_cr("      h: display this help info");
2114   _output->print_cr("      H: display this help info, with examples");
2115   _output->print_cr("      +: traverse in-edges (on if neither + nor -)");
2116   _output->print_cr("      -: traverse out-edges");
2117   _output->print_cr("      c: visit control nodes");
2118   _output->print_cr("      d: visit data nodes");
2119   _output->print_cr("      m: visit memory nodes");
2120   _output->print_cr("      o: visit other nodes");
2121   _output->print_cr("      x: visit mixed nodes");
2122   _output->print_cr("      C: boundary control nodes");
2123   _output->print_cr("      D: boundary data nodes");
2124   _output->print_cr("      M: boundary memory nodes");
2125   _output->print_cr("      O: boundary other nodes");
2126   _output->print_cr("      X: boundary mixed nodes");
2127   _output->print_cr("      #: display node category in color (not supported in all terminals)");
2128   _output->print_cr("      S: sort displayed nodes by node idx");
2129   _output->print_cr("      A: all paths (not just shortest path to target)");
2130   _output->print_cr("      @: print old nodes - before matching (if available)");
2131   _output->print_cr("      B: print scheduling blocks (if available)");
2132   _output->print_cr("      $: dump only, no header, no other columns");
2133   _output->print_cr("      !: show nodes on IGV (sent over network stream)");
2134   _output->print_cr("        (use preferably with dump_bfs(int, Node*, char*, void*, void*, void*)");
2135   _output->print_cr("         to produce a C2 stack trace along with the graph dump, see examples below)");
2136   _output->print_cr("");
2137   _output->print_cr("recursively follow edges to nodes with permitted visit types,");
2138   _output->print_cr("on the boundary additionally display nodes allowed in boundary types");
2139   _output->print_cr("Note: the categories can be overlapping. For example a mixed node");
2140   _output->print_cr("      can contain control and memory output. Some from the other");
2141   _output->print_cr("      category are also control (Halt, Return, etc).");
2142   _output->print_cr("");
2143   _output->print_cr("output columns:");
2144   _output->print_cr("  dist:  BFS distance to this/start");
2145   _output->print_cr("  apd:   all paths distance (d_outputart + d_target)");
2146   _output->print_cr("  block: block identifier, based on _pre_order");
2147   _output->print_cr("  head:  first node in block");
2148   _output->print_cr("  idom:  head node of idom block");
2149   _output->print_cr("  depth: depth of block (_dom_depth)");
2150   _output->print_cr("  old:   old IR node - before matching");
2151   _output->print_cr("  dump:  node->dump()");
2152   _output->print_cr("");
2153   _output->print_cr("Note: if none of the \"cmdxo\" characters are in the options string");
2154   _output->print_cr("      then we set all of them.");
2155   _output->print_cr("      This allows for short strings like \"#\" for colored input traversal");
2156   _output->print_cr("      or \"-#\" for colored output traversal.");
2157   if (print_examples) {
2158     _output->print_cr("");
2159     _output->print_cr("Examples:");
2160     _output->print_cr("  if->dump_bfs(10, 0, \"+cxo\")");
2161     _output->print_cr("    starting at some if node, traverse inputs recursively");
2162     _output->print_cr("    only along control (mixed and other can also be control)");
2163     _output->print_cr("  phi->dump_bfs(5, 0, \"-dxo\")");
2164     _output->print_cr("    starting at phi node, traverse outputs recursively");
2165     _output->print_cr("    only along data (mixed and other can also have data flow)");
2166     _output->print_cr("  find_node(385)->dump_bfs(3, 0, \"cdmox+#@B\")");
2167     _output->print_cr("    find inputs of node 385, up to 3 nodes up (+)");
2168     _output->print_cr("    traverse all nodes (cdmox), use colors (#)");
2169     _output->print_cr("    display old nodes and blocks, if they exist");
2170     _output->print_cr("    useful call to start with");
2171     _output->print_cr("  find_node(102)->dump_bfs(10, 0, \"dCDMOX-\")");
2172     _output->print_cr("    find non-data dependencies of a data node");
2173     _output->print_cr("    follow data node outputs until we find another category");
2174     _output->print_cr("    node as the boundary");
2175     _output->print_cr("  x->dump_bfs(10, y, 0)");
2176     _output->print_cr("    find shortest path from x to y, along any edge or node");
2177     _output->print_cr("    will not find a path if it is longer than 10");
2178     _output->print_cr("    useful to find how x and y are related");
2179     _output->print_cr("  find_node(741)->dump_bfs(20, find_node(746), \"c+\")");
2180     _output->print_cr("    find shortest control path between two nodes");
2181     _output->print_cr("  find_node(741)->dump_bfs(8, find_node(746), \"cdmox+A\")");
2182     _output->print_cr("    find all paths (A) between two nodes of length at most 8");
2183     _output->print_cr("  find_node(741)->dump_bfs(7, find_node(741), \"c+A\")");
2184     _output->print_cr("    find all control loops for this node");
2185     _output->print_cr("  find_node(741)->dump_bfs(7, find_node(741), \"c+A!\", $sp, $fp, $pc)");
2186     _output->print_cr("    same as above, but printing the resulting subgraph");
2187     _output->print_cr("    along with a C2 stack trace on IGV");
2188   }
2189 }
2190 
2191 bool PrintBFS::parse_options() {
2192   if (_options == nullptr) {
2193     _options = "cdmox@B"; // default options
2194   }
2195   size_t len = strlen(_options);
2196   for (size_t i = 0; i < len; i++) {
2197     switch (_options[i]) {
2198       case '+':
2199         _traverse_inputs = true;
2200         break;
2201       case '-':
2202         _traverse_outputs = true;
2203         break;
2204       case 'c':
2205         _filter_visit._control = true;
2206         break;
2207       case 'm':
2208         _filter_visit._memory = true;
2209         break;
2210       case 'd':
2211         _filter_visit._data = true;
2212         break;
2213       case 'x':
2214         _filter_visit._mixed = true;
2215         break;
2216       case 'o':
2217         _filter_visit._other = true;
2218         break;
2219       case 'C':
2220         _filter_boundary._control = true;
2221         break;
2222       case 'M':
2223         _filter_boundary._memory = true;
2224         break;
2225       case 'D':
2226         _filter_boundary._data = true;
2227         break;
2228       case 'X':
2229         _filter_boundary._mixed = true;
2230         break;
2231       case 'O':
2232         _filter_boundary._other = true;
2233         break;
2234       case 'S':
2235         _sort_idx = true;
2236         break;
2237       case 'A':
2238         _all_paths = true;
2239         break;
2240       case '#':
2241         _use_color = true;
2242         break;
2243       case 'B':
2244         _print_blocks = true;
2245         break;
2246       case '@':
2247         _print_old = true;
2248         break;
2249       case '$':
2250         _dump_only = true;
2251         break;
2252       case '!':
2253         _print_igv = true;
2254         break;
2255       case 'h':
2256         print_options_help(false);
2257         return false;
2258        case 'H':
2259         print_options_help(true);
2260         return false;
2261       default:
2262         _output->print_cr("dump_bfs: Unrecognized option \'%c\'", _options[i]);
2263         _output->print_cr("for help, run: find_node(0)->dump_bfs(0,0,\"H\")");
2264         return false;
2265     }
2266   }
2267   if (!_traverse_inputs && !_traverse_outputs) {
2268     _traverse_inputs = true;
2269   }
2270   if (_filter_visit.is_empty()) {
2271     _filter_visit.set_all();
2272   }
2273   Compile* C = Compile::current();
2274   _print_old &= (C->matcher() != nullptr); // only show old if there are new
2275   _print_blocks &= (C->cfg() != nullptr); // only show blocks if available
2276   return true;
2277 }
2278 
2279 void PrintBFS::DumpConfigColored::pre_dump(outputStream* st, const Node* n) {
2280   if (!_bfs->_use_color) {
2281     return;
2282   }
2283   Info* info = _bfs->find_info(n);
2284   if (info == nullptr || !info->is_marked()) {
2285     return;
2286   }
2287 
2288   const Type* t = n->bottom_type();
2289   switch (t->category()) {
2290     case Type::Category::Data:
2291       st->print("\u001b[34m");
2292       break;
2293     case Type::Category::Memory:
2294       st->print("\u001b[32m");
2295       break;
2296     case Type::Category::Mixed:
2297       st->print("\u001b[35m");
2298       break;
2299     case Type::Category::Control:
2300       st->print("\u001b[31m");
2301       break;
2302     case Type::Category::Other:
2303       st->print("\u001b[33m");
2304       break;
2305     case Type::Category::Undef:
2306       n->dump();
2307       assert(false, "category undef ??");
2308       break;
2309     default:
2310       n->dump();
2311       assert(false, "not covered");
2312       break;
2313   }
2314 }
2315 
2316 void PrintBFS::DumpConfigColored::post_dump(outputStream* st) {
2317   if (!_bfs->_use_color) {
2318     return;
2319   }
2320   st->print("\u001b[0m"); // white
2321 }
2322 
2323 Node* PrintBFS::old_node(const Node* n) {
2324   Compile* C = Compile::current();
2325   if (C->matcher() == nullptr || !C->node_arena()->contains(n)) {
2326     return (Node*)nullptr;
2327   } else {
2328     return C->matcher()->find_old_node(n);
2329   }
2330 }
2331 
2332 void PrintBFS::print_node_idx(const Node* n) {
2333   Compile* C = Compile::current();
2334   char buf[30];
2335   if (n == nullptr) {
2336     os::snprintf_checked(buf, sizeof(buf), "_");           // null
2337   } else if (C->node_arena()->contains(n)) {
2338     os::snprintf_checked(buf, sizeof(buf), "%d", n->_idx);  // new node
2339   } else {
2340     os::snprintf_checked(buf, sizeof(buf), "o%d", n->_idx); // old node
2341   }
2342   _output->print("%6s", buf);
2343 }
2344 
2345 void PrintBFS::print_block_id(const Block* b) {
2346   Compile* C = Compile::current();
2347   char buf[30];
2348   os::snprintf_checked(buf, sizeof(buf), "B%d", b->_pre_order);
2349   _output->print("%7s", buf);
2350 }
2351 
2352 void PrintBFS::print_node_block(const Node* n) {
2353   Compile* C = Compile::current();
2354   Block* b = C->node_arena()->contains(n)
2355              ? C->cfg()->get_block_for_node(n)
2356              : nullptr; // guard against old nodes
2357   if (b == nullptr) {
2358     _output->print("      _"); // Block
2359     _output->print("     _");  // head
2360     _output->print("     _");  // idom
2361     _output->print("      _"); // depth
2362   } else {
2363     print_block_id(b);
2364     print_node_idx(b->head());
2365     if (b->_idom) {
2366       print_node_idx(b->_idom->head());
2367     } else {
2368       _output->print("     _"); // idom
2369     }
2370     _output->print("%6d ", b->_dom_depth);
2371   }
2372 }
2373 
2374 // filter, and add to worklist, add info, note traversal edges
2375 void PrintBFS::maybe_traverse(const Node* src, const Node* dst) {
2376   if (dst != nullptr &&
2377      (_filter_visit.accepts(dst) ||
2378       _filter_boundary.accepts(dst) ||
2379       dst == _start)) { // correct category or start?
2380     if (find_info(dst) == nullptr) {
2381       // never visited - set up info
2382       _worklist.push(dst);
2383       int d = 0;
2384       if (dst != _start) {
2385         d = find_info(src)->distance() + 1;
2386       }
2387       make_info(dst, d);
2388     }
2389     if (src != dst) {
2390       // traversal edges useful during select
2391       find_info(dst)->edge_bwd.push(src);
2392     }
2393   }
2394 }
2395 
2396 void PrintBFS::print_header() const {
2397   if (_dump_only) {
2398     return; // no header in dump only mode
2399   }
2400   _output->print("dist");                         // distance
2401   if (_all_paths) {
2402     _output->print(" apd");                       // all paths distance
2403   }
2404   if (_print_blocks) {
2405     _output->print(" [block  head  idom depth]"); // block
2406   }
2407   if (_print_old) {
2408     _output->print("   old");                     // old node
2409   }
2410   _output->print(" dump\n");                      // node dump
2411   _output->print_cr("---------------------------------------------");
2412 }
2413 
2414 void PrintBFS::print_node(const Node* n) {
2415   if (_dump_only) {
2416     n->dump("\n", false, _output, &_dcc);
2417     return;
2418   }
2419   _output->print("%4d", find_info(n)->distance());// distance
2420   if (_all_paths) {
2421     Info* info = find_info(n);
2422     int apd = info->distance() + info->distance_from_target();
2423     _output->print("%4d", apd);                   // all paths distance
2424   }
2425   if (_print_blocks) {
2426     print_node_block(n);                          // block
2427   }
2428   if (_print_old) {
2429     print_node_idx(old_node(n));                  // old node
2430   }
2431   _output->print(" ");
2432   n->dump("\n", false, _output, &_dcc);           // node dump
2433 }
2434 
2435 //------------------------------dump_bfs--------------------------------------
2436 // Call this from debugger
2437 // Useful for BFS traversal, shortest path, all path, loop detection, etc
2438 // Designed to be more readable, and provide additional info
2439 // To find all options, run:
2440 //   find_node(0)->dump_bfs(0,0,"H")
2441 void Node::dump_bfs(const int max_distance, Node* target, const char* options) const {
2442   dump_bfs(max_distance, target, options, tty);
2443 }
2444 
2445 // Used to dump to stream.
2446 void Node::dump_bfs(const int max_distance, Node* target, const char* options, outputStream* st, const frame* fr) const {
2447   PrintBFS bfs(this, max_distance, target, options, st, fr);
2448   bfs.run();
2449 }
2450 
2451 // Call this from debugger, with default arguments
2452 void Node::dump_bfs(const int max_distance) const {
2453   dump_bfs(max_distance, nullptr, nullptr);
2454 }
2455 
2456 // Call this from debugger, with stack handling register arguments for IGV dumps.
2457 // Example: p find_node(741)->dump_bfs(7, find_node(741), "c+A!", $sp, $fp, $pc).
2458 void Node::dump_bfs(const int max_distance, Node* target, const char* options, void* sp, void* fp, void* pc) const {
2459   frame fr(sp, fp, pc);
2460   dump_bfs(max_distance, target, options, tty, &fr);
2461 }
2462 
2463 // -----------------------------dump_idx---------------------------------------
2464 void Node::dump_idx(bool align, outputStream* st, DumpConfig* dc) const {
2465   if (dc != nullptr) {
2466     dc->pre_dump(st, this);
2467   }
2468   Compile* C = Compile::current();
2469   bool is_new = C->node_arena()->contains(this);
2470   if (align) { // print prefix empty spaces$
2471     // +1 for leading digit, +1 for "o"
2472     uint max_width = (C->unique() == 0 ? 0 : static_cast<uint>(log10(static_cast<double>(C->unique())))) + 2;
2473     // +1 for leading digit, maybe +1 for "o"
2474     uint width = (_idx == 0 ? 0 : static_cast<uint>(log10(static_cast<double>(_idx)))) + 1 + (is_new ? 0 : 1);
2475     while (max_width > width) {
2476       st->print(" ");
2477       width++;
2478     }
2479   }
2480   if (!is_new) {
2481     st->print("o");
2482   }
2483   st->print("%d", _idx);
2484   if (dc != nullptr) {
2485     dc->post_dump(st);
2486   }
2487 }
2488 
2489 // -----------------------------dump_name--------------------------------------
2490 void Node::dump_name(outputStream* st, DumpConfig* dc) const {
2491   if (dc != nullptr) {
2492     dc->pre_dump(st, this);
2493   }
2494   st->print("%s", Name());
2495   if (dc != nullptr) {
2496     dc->post_dump(st);
2497   }
2498 }
2499 
2500 // -----------------------------Name-------------------------------------------
2501 extern const char *NodeClassNames[];
2502 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
2503 
2504 static bool is_disconnected(const Node* n) {
2505   for (uint i = 0; i < n->req(); i++) {
2506     if (n->in(i) != nullptr)  return false;
2507   }
2508   return true;
2509 }
2510 
2511 #ifdef ASSERT
2512 void Node::dump_orig(outputStream *st, bool print_key) const {
2513   Compile* C = Compile::current();
2514   Node* orig = _debug_orig;
2515   if (not_a_node(orig)) orig = nullptr;
2516   if (orig != nullptr && !C->node_arena()->contains(orig)) orig = nullptr;
2517   if (orig == nullptr) return;
2518   if (print_key) {
2519     st->print(" !orig=");
2520   }
2521   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
2522   if (not_a_node(fast)) fast = nullptr;
2523   while (orig != nullptr) {
2524     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
2525     if (discon) st->print("[");
2526     if (!Compile::current()->node_arena()->contains(orig))
2527       st->print("o");
2528     st->print("%d", orig->_idx);
2529     if (discon) st->print("]");
2530     orig = orig->debug_orig();
2531     if (not_a_node(orig)) orig = nullptr;
2532     if (orig != nullptr && !C->node_arena()->contains(orig)) orig = nullptr;
2533     if (orig != nullptr) st->print(",");
2534     if (fast != nullptr) {
2535       // Step fast twice for each single step of orig:
2536       fast = fast->debug_orig();
2537       if (not_a_node(fast)) fast = nullptr;
2538       if (fast != nullptr && fast != orig) {
2539         fast = fast->debug_orig();
2540         if (not_a_node(fast)) fast = nullptr;
2541       }
2542       if (fast == orig) {
2543         st->print("...");
2544         break;
2545       }
2546     }
2547   }
2548 }
2549 
2550 void Node::set_debug_orig(Node* orig) {
2551   _debug_orig = orig;
2552   if (BreakAtNode == 0)  return;
2553   if (not_a_node(orig))  orig = nullptr;
2554   int trip = 10;
2555   while (orig != nullptr) {
2556     if (orig->debug_idx() == BreakAtNode || (uintx)orig->_idx == BreakAtNode) {
2557       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=" UINT64_FORMAT " orig._idx=%d orig._debug_idx=" UINT64_FORMAT,
2558                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
2559       BREAKPOINT;
2560     }
2561     orig = orig->debug_orig();
2562     if (not_a_node(orig))  orig = nullptr;
2563     if (trip-- <= 0)  break;
2564   }
2565 }
2566 #endif //ASSERT
2567 
2568 //------------------------------dump------------------------------------------
2569 // Dump a Node
2570 void Node::dump(const char* suffix, bool mark, outputStream* st, DumpConfig* dc) const {
2571   Compile* C = Compile::current();
2572   bool is_new = C->node_arena()->contains(this);
2573   C->_in_dump_cnt++;
2574 
2575   // idx mark name ===
2576   dump_idx(true, st, dc);
2577   st->print(mark ? " >" : "  ");
2578   dump_name(st, dc);
2579   st->print("  === ");
2580 
2581   // Dump the required and precedence inputs
2582   dump_req(st, dc);
2583   dump_prec(st, dc);
2584   // Dump the outputs
2585   dump_out(st, dc);
2586 
2587   if (is_disconnected(this)) {
2588 #ifdef ASSERT
2589     st->print("  [" UINT64_FORMAT "]", debug_idx());
2590     dump_orig(st);
2591 #endif
2592     st->cr();
2593     C->_in_dump_cnt--;
2594     return;                     // don't process dead nodes
2595   }
2596 
2597   if (C->clone_map().value(_idx) != 0) {
2598     C->clone_map().dump(_idx, st);
2599   }
2600   // Dump node-specific info
2601   dump_spec(st);
2602 #ifdef ASSERT
2603   // Dump the non-reset _debug_idx
2604   if (Verbose && WizardMode) {
2605     st->print("  [" UINT64_FORMAT "]", debug_idx());
2606   }
2607 #endif
2608 
2609   const Type *t = bottom_type();
2610 
2611   if (t != nullptr && (t->isa_instptr() || t->isa_instklassptr())) {
2612     const TypeInstPtr  *toop = t->isa_instptr();
2613     const TypeInstKlassPtr *tkls = t->isa_instklassptr();
2614     if (toop) {
2615       st->print("  Oop:");
2616     } else if (tkls) {
2617       st->print("  Klass:");
2618     }
2619     t->dump_on(st);
2620   } else if (t == Type::MEMORY) {
2621     st->print("  Memory:");
2622     MemNode::dump_adr_type(adr_type(), st);
2623   } else if (Verbose || WizardMode) {
2624     st->print("  Type:");
2625     if (t) {
2626       t->dump_on(st);
2627     } else {
2628       st->print("no type");
2629     }
2630   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
2631     // Dump MachSpillcopy vector type.
2632     t->dump_on(st);
2633   }
2634   if (is_new) {
2635     DEBUG_ONLY(dump_orig(st));
2636     Node_Notes* nn = C->node_notes_at(_idx);
2637     if (nn != nullptr && !nn->is_clear()) {
2638       if (nn->jvms() != nullptr) {
2639         st->print(" !jvms:");
2640         nn->jvms()->dump_spec(st);
2641       }
2642     }
2643   }
2644   if (suffix) st->print("%s", suffix);
2645   C->_in_dump_cnt--;
2646 }
2647 
2648 // call from debugger: dump node to tty with newline
2649 void Node::dump() const {
2650   dump("\n");
2651 }
2652 
2653 //------------------------------dump_req--------------------------------------
2654 void Node::dump_req(outputStream* st, DumpConfig* dc) const {
2655   // Dump the required input edges
2656   for (uint i = 0; i < req(); i++) {    // For all required inputs
2657     Node* d = in(i);
2658     if (d == nullptr) {
2659       st->print("_ ");
2660     } else if (not_a_node(d)) {
2661       st->print("not_a_node ");  // uninitialized, sentinel, garbage, etc.
2662     } else {
2663       d->dump_idx(false, st, dc);
2664       st->print(" ");
2665     }
2666   }
2667 }
2668 
2669 
2670 //------------------------------dump_prec-------------------------------------
2671 void Node::dump_prec(outputStream* st, DumpConfig* dc) const {
2672   // Dump the precedence edges
2673   int any_prec = 0;
2674   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
2675     Node* p = in(i);
2676     if (p != nullptr) {
2677       if (!any_prec++) st->print(" |");
2678       if (not_a_node(p)) { st->print("not_a_node "); continue; }
2679       p->dump_idx(false, st, dc);
2680       st->print(" ");
2681     }
2682   }
2683 }
2684 
2685 //------------------------------dump_out--------------------------------------
2686 void Node::dump_out(outputStream* st, DumpConfig* dc) const {
2687   // Delimit the output edges
2688   st->print(" [[ ");
2689   // Dump the output edges
2690   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
2691     Node* u = _out[i];
2692     if (u == nullptr) {
2693       st->print("_ ");
2694     } else if (not_a_node(u)) {
2695       st->print("not_a_node ");
2696     } else {
2697       u->dump_idx(false, st, dc);
2698       st->print(" ");
2699     }
2700   }
2701   st->print("]] ");
2702 }
2703 
2704 //------------------------------dump-------------------------------------------
2705 // call from debugger: dump Node's inputs (or outputs if d negative)
2706 void Node::dump(int d) const {
2707   dump_bfs(abs(d), nullptr, (d > 0) ? "+$" : "-$");
2708 }
2709 
2710 //------------------------------dump_ctrl--------------------------------------
2711 // call from debugger: dump Node's control inputs (or outputs if d negative)
2712 void Node::dump_ctrl(int d) const {
2713   dump_bfs(abs(d), nullptr, (d > 0) ? "+$c" : "-$c");
2714 }
2715 
2716 //-----------------------------dump_compact------------------------------------
2717 void Node::dump_comp() const {
2718   this->dump_comp("\n");
2719 }
2720 
2721 //-----------------------------dump_compact------------------------------------
2722 // Dump a Node in compact representation, i.e., just print its name and index.
2723 // Nodes can specify additional specifics to print in compact representation by
2724 // implementing dump_compact_spec.
2725 void Node::dump_comp(const char* suffix, outputStream *st) const {
2726   Compile* C = Compile::current();
2727   C->_in_dump_cnt++;
2728   st->print("%s(%d)", Name(), _idx);
2729   this->dump_compact_spec(st);
2730   if (suffix) {
2731     st->print("%s", suffix);
2732   }
2733   C->_in_dump_cnt--;
2734 }
2735 
2736 // VERIFICATION CODE
2737 // Verify all nodes if verify_depth is negative
2738 void Node::verify(int verify_depth, VectorSet& visited, Node_List& worklist) {
2739   assert(verify_depth != 0, "depth should not be 0");
2740   Compile* C = Compile::current();
2741   uint last_index_on_current_depth = worklist.size() - 1;
2742   verify_depth--; // Visiting the first node on depth 1
2743   // Only add nodes to worklist if verify_depth is negative (visit all nodes) or greater than 0
2744   bool add_to_worklist = verify_depth != 0;
2745 
2746   for (uint list_index = 0; list_index < worklist.size(); list_index++) {
2747     Node* n = worklist[list_index];
2748 
2749     if (n->is_Con() && n->bottom_type() == Type::TOP) {
2750       if (C->cached_top_node() == nullptr) {
2751         C->set_cached_top_node((Node*)n);
2752       }
2753       assert(C->cached_top_node() == n, "TOP node must be unique");
2754     }
2755 
2756     uint in_len = n->len();
2757     for (uint i = 0; i < in_len; i++) {
2758       Node* x = n->_in[i];
2759       if (!x || x->is_top()) {
2760         continue;
2761       }
2762 
2763       // Verify my input has a def-use edge to me
2764       // Count use-def edges from n to x
2765       int cnt = 1;
2766       for (uint j = 0; j < i; j++) {
2767         if (n->_in[j] == x) {
2768           cnt++;
2769           break;
2770         }
2771       }
2772       if (cnt == 2) {
2773         // x is already checked as n's previous input, skip its duplicated def-use count checking
2774         continue;
2775       }
2776       for (uint j = i + 1; j < in_len; j++) {
2777         if (n->_in[j] == x) {
2778           cnt++;
2779         }
2780       }
2781 
2782       // Count def-use edges from x to n
2783       uint max = x->_outcnt;
2784       for (uint k = 0; k < max; k++) {
2785         if (x->_out[k] == n) {
2786           cnt--;
2787         }
2788       }
2789       assert(cnt == 0, "mismatched def-use edge counts");
2790 
2791       if (add_to_worklist && !visited.test_set(x->_idx)) {
2792         worklist.push(x);
2793       }
2794     }
2795 
2796     if (verify_depth > 0 && list_index == last_index_on_current_depth) {
2797       // All nodes on this depth were processed and its inputs are on the worklist. Decrement verify_depth and
2798       // store the current last list index which is the last node in the list with the new depth. All nodes
2799       // added afterwards will have a new depth again. Stop adding new nodes if depth limit is reached (=0).
2800       verify_depth--;
2801       if (verify_depth == 0) {
2802         add_to_worklist = false;
2803       }
2804       last_index_on_current_depth = worklist.size() - 1;
2805     }
2806   }
2807 }
2808 #endif // not PRODUCT
2809 
2810 //------------------------------Registers--------------------------------------
2811 // Do we Match on this edge index or not?  Generally false for Control
2812 // and true for everything else.  Weird for calls & returns.
2813 uint Node::match_edge(uint idx) const {
2814   return idx;                   // True for other than index 0 (control)
2815 }
2816 
2817 // Register classes are defined for specific machines
2818 const RegMask &Node::out_RegMask() const {
2819   ShouldNotCallThis();
2820   return RegMask::EMPTY;
2821 }
2822 
2823 const RegMask &Node::in_RegMask(uint) const {
2824   ShouldNotCallThis();
2825   return RegMask::EMPTY;
2826 }
2827 
2828 void Node_Array::grow(uint i) {
2829   assert(i >= _max, "Should have been checked before, use maybe_grow?");
2830   assert(_max > 0, "invariant");
2831   uint old = _max;
2832   _max = next_power_of_2(i);
2833   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2834   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2835 }
2836 
2837 void Node_Array::insert(uint i, Node* n) {
2838   if (_nodes[_max - 1]) {
2839     grow(_max);
2840   }
2841   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i + 1], ((_max - i - 1) * sizeof(Node*)));
2842   _nodes[i] = n;
2843 }
2844 
2845 void Node_Array::remove(uint i) {
2846   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i + 1], (HeapWord*)&_nodes[i], ((_max - i - 1) * sizeof(Node*)));
2847   _nodes[_max - 1] = nullptr;
2848 }
2849 
2850 void Node_Array::dump() const {
2851 #ifndef PRODUCT
2852   for (uint i = 0; i < _max; i++) {
2853     Node* nn = _nodes[i];
2854     if (nn != nullptr) {
2855       tty->print("%5d--> ",i); nn->dump();
2856     }
2857   }
2858 #endif
2859 }
2860 
2861 //--------------------------is_iteratively_computed------------------------------
2862 // Operation appears to be iteratively computed (such as an induction variable)
2863 // It is possible for this operation to return false for a loop-varying
2864 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2865 bool Node::is_iteratively_computed() {
2866   if (ideal_reg()) { // does operation have a result register?
2867     for (uint i = 1; i < req(); i++) {
2868       Node* n = in(i);
2869       if (n != nullptr && n->is_Phi()) {
2870         for (uint j = 1; j < n->req(); j++) {
2871           if (n->in(j) == this) {
2872             return true;
2873           }
2874         }
2875       }
2876     }
2877   }
2878   return false;
2879 }
2880 
2881 //--------------------------find_similar------------------------------
2882 // Return a node with opcode "opc" and same inputs as "this" if one can
2883 // be found; Otherwise return null;
2884 Node* Node::find_similar(int opc) {
2885   if (req() >= 2) {
2886     Node* def = in(1);
2887     if (def && def->outcnt() >= 2) {
2888       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2889         Node* use = def->fast_out(i);
2890         if (use != this &&
2891             use->Opcode() == opc &&
2892             use->req() == req()) {
2893           uint j;
2894           for (j = 0; j < use->req(); j++) {
2895             if (use->in(j) != in(j)) {
2896               break;
2897             }
2898           }
2899           if (j == use->req()) {
2900             return use;
2901           }
2902         }
2903       }
2904     }
2905   }
2906   return nullptr;
2907 }
2908 
2909 Node* Node::unique_multiple_edges_out_or_null() const {
2910   Node* use = nullptr;
2911   for (DUIterator_Fast kmax, k = fast_outs(kmax); k < kmax; k++) {
2912     Node* u = fast_out(k);
2913     if (use == nullptr) {
2914       use = u; // first use
2915     } else if (u != use) {
2916       return nullptr; // not unique
2917     } else {
2918       // secondary use
2919     }
2920   }
2921   return use;
2922 }
2923 
2924 //--------------------------unique_ctrl_out_or_null-------------------------
2925 // Return the unique control out if only one. Null if none or more than one.
2926 Node* Node::unique_ctrl_out_or_null() const {
2927   Node* found = nullptr;
2928   for (uint i = 0; i < outcnt(); i++) {
2929     Node* use = raw_out(i);
2930     if (use->is_CFG() && use != this) {
2931       if (found != nullptr) {
2932         return nullptr;
2933       }
2934       found = use;
2935     }
2936   }
2937   return found;
2938 }
2939 
2940 //--------------------------unique_ctrl_out------------------------------
2941 // Return the unique control out. Asserts if none or more than one control out.
2942 Node* Node::unique_ctrl_out() const {
2943   Node* ctrl = unique_ctrl_out_or_null();
2944   assert(ctrl != nullptr, "control out is assumed to be unique");
2945   return ctrl;
2946 }
2947 
2948 void Node::ensure_control_or_add_prec(Node* c) {
2949   if (in(0) == nullptr) {
2950     set_req(0, c);
2951   } else if (in(0) != c) {
2952     add_prec(c);
2953   }
2954 }
2955 
2956 void Node::add_prec_from(Node* n) {
2957   for (uint i = n->req(); i < n->len(); i++) {
2958     Node* prec = n->in(i);
2959     if (prec != nullptr) {
2960       add_prec(prec);
2961     }
2962   }
2963 }
2964 
2965 bool Node::is_dead_loop_safe() const {
2966   if (is_Phi()) {
2967     return true;
2968   }
2969   if (is_Proj() && in(0) == nullptr)  {
2970     return true;
2971   }
2972   if ((_flags & (Flag_is_dead_loop_safe | Flag_is_Con)) != 0) {
2973     if (!is_Proj()) {
2974       return true;
2975     }
2976     if (in(0)->is_Allocate()) {
2977       return false;
2978     }
2979     // MemNode::can_see_stored_value() peeks through the boxing call
2980     if (in(0)->is_CallStaticJava() && in(0)->as_CallStaticJava()->is_boxing_method()) {
2981       return false;
2982     }
2983     return true;
2984   }
2985   return false;
2986 }
2987 
2988 bool Node::is_div_or_mod(BasicType bt) const { return Opcode() == Op_Div(bt) || Opcode() == Op_Mod(bt) ||
2989                                                       Opcode() == Op_UDiv(bt) || Opcode() == Op_UMod(bt); }
2990 
2991 // `maybe_pure_function` is assumed to be the input of `this`. This is a bit redundant,
2992 // but we already have and need maybe_pure_function in all the call sites, so
2993 // it makes it obvious that the `maybe_pure_function` is the same node as in the caller,
2994 // while it takes more thinking to realize that a locally computed in(0) must be equal to
2995 // the local in the caller.
2996 bool Node::is_data_proj_of_pure_function(const Node* maybe_pure_function) const {
2997   return Opcode() == Op_Proj && as_Proj()->_con == TypeFunc::Parms && maybe_pure_function->is_CallLeafPure();
2998 }
2999 
3000 //=============================================================================
3001 //------------------------------yank-------------------------------------------
3002 // Find and remove
3003 void Node_List::yank( Node *n ) {
3004   uint i;
3005   for (i = 0; i < _cnt; i++) {
3006     if (_nodes[i] == n) {
3007       break;
3008     }
3009   }
3010 
3011   if (i < _cnt) {
3012     _nodes[i] = _nodes[--_cnt];
3013   }
3014 }
3015 
3016 //------------------------------dump-------------------------------------------
3017 void Node_List::dump() const {
3018 #ifndef PRODUCT
3019   for (uint i = 0; i < _cnt; i++) {
3020     if (_nodes[i]) {
3021       tty->print("%5d--> ", i);
3022       _nodes[i]->dump();
3023     }
3024   }
3025 #endif
3026 }
3027 
3028 void Node_List::dump_simple() const {
3029 #ifndef PRODUCT
3030   for (uint i = 0; i < _cnt; i++) {
3031     if( _nodes[i] ) {
3032       tty->print(" %d", _nodes[i]->_idx);
3033     } else {
3034       tty->print(" null");
3035     }
3036   }
3037 #endif
3038 }
3039 
3040 //=============================================================================
3041 //------------------------------remove-----------------------------------------
3042 void Unique_Node_List::remove(Node* n) {
3043   if (_in_worklist.test(n->_idx)) {
3044     for (uint i = 0; i < size(); i++) {
3045       if (_nodes[i] == n) {
3046         map(i, Node_List::pop());
3047         _in_worklist.remove(n->_idx);
3048         return;
3049       }
3050     }
3051     ShouldNotReachHere();
3052   }
3053 }
3054 
3055 //-----------------------remove_useless_nodes----------------------------------
3056 // Remove useless nodes from worklist
3057 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
3058   for (uint i = 0; i < size(); ++i) {
3059     Node *n = at(i);
3060     assert( n != nullptr, "Did not expect null entries in worklist");
3061     if (!useful.test(n->_idx)) {
3062       _in_worklist.remove(n->_idx);
3063       map(i, Node_List::pop());
3064       --i;  // Visit popped node
3065       // If it was last entry, loop terminates since size() was also reduced
3066     }
3067   }
3068 }
3069 
3070 //=============================================================================
3071 void Node_Stack::grow() {
3072   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
3073   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
3074   size_t max = old_max << 1;             // max * 2
3075   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
3076   _inode_max = _inodes + max;
3077   _inode_top = _inodes + old_top;        // restore _top
3078 }
3079 
3080 // Node_Stack is used to map nodes.
3081 Node* Node_Stack::find(uint idx) const {
3082   uint sz = size();
3083   for (uint i = 0; i < sz; i++) {
3084     if (idx == index_at(i)) {
3085       return node_at(i);
3086     }
3087   }
3088   return nullptr;
3089 }
3090 
3091 //=============================================================================
3092 uint TypeNode::size_of() const { return sizeof(*this); }
3093 #ifndef PRODUCT
3094 void TypeNode::dump_spec(outputStream *st) const {
3095   if (!Verbose && !WizardMode) {
3096     // standard dump does this in Verbose and WizardMode
3097     st->print(" #"); _type->dump_on(st);
3098   }
3099 }
3100 
3101 void TypeNode::dump_compact_spec(outputStream *st) const {
3102   st->print("#");
3103   _type->dump_on(st);
3104 }
3105 #endif
3106 uint TypeNode::hash() const {
3107   return Node::hash() + _type->hash();
3108 }
3109 bool TypeNode::cmp(const Node& n) const {
3110   return Type::equals(_type, n.as_Type()->_type);
3111 }
3112 const Type* TypeNode::bottom_type() const { return _type; }
3113 const Type* TypeNode::Value(PhaseGVN* phase) const { return _type; }
3114 
3115 //------------------------------ideal_reg--------------------------------------
3116 uint TypeNode::ideal_reg() const {
3117   return _type->ideal_reg();
3118 }
3119 
3120 void TypeNode::make_path_dead(PhaseIterGVN* igvn, PhaseIdealLoop* loop, Node* ctrl_use, uint j, const char* phase_str) {
3121   Node* c = ctrl_use->in(j);
3122   if (igvn->type(c) != Type::TOP) {
3123     igvn->replace_input_of(ctrl_use, j, igvn->C->top());
3124     create_halt_path(igvn, c, loop, phase_str);
3125   }
3126 }
3127 
3128 // This Type node is dead. It could be because the type that it captures and the type of the node computed from its
3129 // inputs do not intersect anymore. That node has some uses along some control flow paths. Those control flow paths must
3130 // be unreachable as using a dead value makes no sense. For the Type node to capture a narrowed down type, some control
3131 // flow construct must guard the Type node (an If node usually). When the Type node becomes dead, the guard usually
3132 // constant folds and the control flow that leads to the Type node becomes unreachable. There are cases where that
3133 // doesn't happen, however. They are handled here by following uses of the Type node until a CFG or a Phi to find dead
3134 // paths. The dead paths are then replaced by a Halt node.
3135 void TypeNode::make_paths_from_here_dead(PhaseIterGVN* igvn, PhaseIdealLoop* loop, const char* phase_str) {
3136   Unique_Node_List wq;
3137   wq.push(this);
3138   for (uint i = 0; i < wq.size(); ++i) {
3139     Node* n = wq.at(i);
3140     for (DUIterator_Fast kmax, k = n->fast_outs(kmax); k < kmax; k++) {
3141       Node* u = n->fast_out(k);
3142       if (u->is_CFG()) {
3143         assert(!u->is_Region(), "Can't reach a Region without going through a Phi");
3144         make_path_dead(igvn, loop, u, 0, phase_str);
3145       } else if (u->is_Phi()) {
3146         Node* r = u->in(0);
3147         assert(r->is_Region() || r->is_top(), "unexpected Phi's control");
3148         if (r->is_Region()) {
3149           for (uint j = 1; j < u->req(); ++j) {
3150             if (u->in(j) == n && r->in(j) != nullptr) {
3151               make_path_dead(igvn, loop, r, j, phase_str);
3152             }
3153           }
3154         }
3155       } else {
3156         wq.push(u);
3157       }
3158     }
3159   }
3160 }
3161 
3162 void TypeNode::create_halt_path(PhaseIterGVN* igvn, Node* c, PhaseIdealLoop* loop, const char* phase_str) const {
3163   Node* frame = new ParmNode(igvn->C->start(), TypeFunc::FramePtr);
3164   if (loop == nullptr) {
3165     igvn->register_new_node_with_optimizer(frame);
3166   } else {
3167     loop->register_new_node(frame, igvn->C->start());
3168   }
3169 
3170   stringStream ss;
3171   ss.print("dead path discovered by TypeNode during %s", phase_str);
3172 
3173   Node* halt = new HaltNode(c, frame, ss.as_string(igvn->C->comp_arena()));
3174   if (loop == nullptr) {
3175     igvn->register_new_node_with_optimizer(halt);
3176   } else {
3177     loop->register_control(halt, loop->ltree_root(), c);
3178   }
3179   igvn->add_input_to(igvn->C->root(), halt);
3180 }
3181 
3182 Node* TypeNode::Ideal(PhaseGVN* phase, bool can_reshape) {
3183   if (KillPathsReachableByDeadTypeNode && can_reshape && Value(phase) == Type::TOP) {
3184     PhaseIterGVN* igvn = phase->is_IterGVN();
3185     Node* top = igvn->C->top();
3186     ResourceMark rm;
3187     make_paths_from_here_dead(igvn, nullptr, "igvn");
3188     return top;
3189   }
3190 
3191   return Node::Ideal(phase, can_reshape);
3192 }
3193 
--- EOF ---