1 /*
   2  * Copyright (c) 1997, 2026, 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/reachability.hpp"
  43 #include "opto/regmask.hpp"
  44 #include "opto/rootnode.hpp"
  45 #include "opto/type.hpp"
  46 #include "utilities/copy.hpp"
  47 #include "utilities/macros.hpp"
  48 #include "utilities/powerOfTwo.hpp"
  49 #include "utilities/stringUtils.hpp"
  50 
  51 class RegMask;
  52 // #include "phase.hpp"
  53 class PhaseTransform;
  54 class PhaseGVN;
  55 
  56 // Arena we are currently building Nodes in
  57 const uint Node::NotAMachineReg = 0xffff0000;
  58 
  59 #ifndef PRODUCT
  60 extern uint nodes_created;
  61 #endif
  62 #ifdef __clang__
  63 #pragma clang diagnostic push
  64 #pragma GCC diagnostic ignored "-Wuninitialized"
  65 #endif
  66 
  67 #ifdef ASSERT
  68 
  69 //-------------------------- construct_node------------------------------------
  70 // Set a breakpoint here to identify where a particular node index is built.
  71 void Node::verify_construction() {
  72   _debug_orig = nullptr;
  73   // The decimal digits of _debug_idx are <compile_id> followed by 10 digits of <_idx>
  74   Compile* C = Compile::current();
  75   assert(C->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  76   uint64_t new_debug_idx = (uint64_t)C->compile_id() * 10000000000 + _idx;
  77   set_debug_idx(new_debug_idx);
  78   if (!C->phase_optimize_finished()) {
  79     // Only check assert during parsing and optimization phase. Skip it while generating code.
  80     assert(C->live_nodes() <= C->max_node_limit(), "Live Node limit exceeded limit");
  81   }
  82   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (uint64_t)_idx == BreakAtNode)) {
  83     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=" UINT64_FORMAT, _idx, _debug_idx);
  84     BREAKPOINT;
  85   }
  86 #if OPTO_DU_ITERATOR_ASSERT
  87   _last_del = nullptr;
  88   _del_tick = 0;
  89 #endif
  90   _hash_lock = 0;
  91 }
  92 
  93 
  94 // #ifdef ASSERT ...
  95 
  96 #if OPTO_DU_ITERATOR_ASSERT
  97 void DUIterator_Common::sample(const Node* node) {
  98   _vdui     = VerifyDUIterators;
  99   _node     = node;
 100   _outcnt   = node->_outcnt;
 101   _del_tick = node->_del_tick;
 102   _last     = nullptr;
 103 }
 104 
 105 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
 106   assert(_node     == node, "consistent iterator source");
 107   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
 108 }
 109 
 110 void DUIterator_Common::verify_resync() {
 111   // Ensure that the loop body has just deleted the last guy produced.
 112   const Node* node = _node;
 113   // Ensure that at least one copy of the last-seen edge was deleted.
 114   // Note:  It is OK to delete multiple copies of the last-seen edge.
 115   // Unfortunately, we have no way to verify that all the deletions delete
 116   // that same edge.  On this point we must use the Honor System.
 117   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 118   assert(node->_last_del == _last, "must have deleted the edge just produced");
 119   // We liked this deletion, so accept the resulting outcnt and tick.
 120   _outcnt   = node->_outcnt;
 121   _del_tick = node->_del_tick;
 122 }
 123 
 124 void DUIterator_Common::reset(const DUIterator_Common& that) {
 125   if (this == &that)  return;  // ignore assignment to self
 126   if (!_vdui) {
 127     // We need to initialize everything, overwriting garbage values.
 128     _last = that._last;
 129     _vdui = that._vdui;
 130   }
 131   // Note:  It is legal (though odd) for an iterator over some node x
 132   // to be reassigned to iterate over another node y.  Some doubly-nested
 133   // progress loops depend on being able to do this.
 134   const Node* node = that._node;
 135   // Re-initialize everything, except _last.
 136   _node     = node;
 137   _outcnt   = node->_outcnt;
 138   _del_tick = node->_del_tick;
 139 }
 140 
 141 void DUIterator::sample(const Node* node) {
 142   DUIterator_Common::sample(node);      // Initialize the assertion data.
 143   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 144 }
 145 
 146 void DUIterator::verify(const Node* node, bool at_end_ok) {
 147   DUIterator_Common::verify(node, at_end_ok);
 148   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 149 }
 150 
 151 void DUIterator::verify_increment() {
 152   if (_refresh_tick & 1) {
 153     // We have refreshed the index during this loop.
 154     // Fix up _idx to meet asserts.
 155     if (_idx > _outcnt)  _idx = _outcnt;
 156   }
 157   verify(_node, true);
 158 }
 159 
 160 void DUIterator::verify_resync() {
 161   // Note:  We do not assert on _outcnt, because insertions are OK here.
 162   DUIterator_Common::verify_resync();
 163   // Make sure we are still in sync, possibly with no more out-edges:
 164   verify(_node, true);
 165 }
 166 
 167 void DUIterator::reset(const DUIterator& that) {
 168   if (this == &that)  return;  // self assignment is always a no-op
 169   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 170   assert(that._idx          == 0, "assign only the result of Node::outs()");
 171   assert(_idx               == that._idx, "already assigned _idx");
 172   if (!_vdui) {
 173     // We need to initialize everything, overwriting garbage values.
 174     sample(that._node);
 175   } else {
 176     DUIterator_Common::reset(that);
 177     if (_refresh_tick & 1) {
 178       _refresh_tick++;                  // Clear the "was refreshed" flag.
 179     }
 180     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 181   }
 182 }
 183 
 184 void DUIterator::refresh() {
 185   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 186   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 187 }
 188 
 189 void DUIterator::verify_finish() {
 190   // If the loop has killed the node, do not require it to re-run.
 191   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 192   // If this assert triggers, it means that a loop used refresh_out_pos
 193   // to re-synch an iteration index, but the loop did not correctly
 194   // re-run itself, using a "while (progress)" construct.
 195   // This iterator enforces the rule that you must keep trying the loop
 196   // until it "runs clean" without any need for refreshing.
 197   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 198 }
 199 
 200 
 201 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 202   DUIterator_Common::verify(node, at_end_ok);
 203   Node** out    = node->_out;
 204   uint   cnt    = node->_outcnt;
 205   assert(cnt == _outcnt, "no insertions allowed");
 206   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 207   // This last check is carefully designed to work for NO_OUT_ARRAY.
 208 }
 209 
 210 void DUIterator_Fast::verify_limit() {
 211   const Node* node = _node;
 212   verify(node, true);
 213   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 214 }
 215 
 216 void DUIterator_Fast::verify_resync() {
 217   const Node* node = _node;
 218   if (_outp == node->_out + _outcnt) {
 219     // Note that the limit imax, not the pointer i, gets updated with the
 220     // exact count of deletions.  (For the pointer it's always "--i".)
 221     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 222     // This is a limit pointer, with a name like "imax".
 223     // Fudge the _last field so that the common assert will be happy.
 224     _last = (Node*) node->_last_del;
 225     DUIterator_Common::verify_resync();
 226   } else {
 227     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 228     // A normal internal pointer.
 229     DUIterator_Common::verify_resync();
 230     // Make sure we are still in sync, possibly with no more out-edges:
 231     verify(node, true);
 232   }
 233 }
 234 
 235 void DUIterator_Fast::verify_relimit(uint n) {
 236   const Node* node = _node;
 237   assert((int)n > 0, "use imax -= n only with a positive count");
 238   // This must be a limit pointer, with a name like "imax".
 239   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 240   // The reported number of deletions must match what the node saw.
 241   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 242   // Fudge the _last field so that the common assert will be happy.
 243   _last = (Node*) node->_last_del;
 244   DUIterator_Common::verify_resync();
 245 }
 246 
 247 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 248   assert(_outp              == that._outp, "already assigned _outp");
 249   DUIterator_Common::reset(that);
 250 }
 251 
 252 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 253   // at_end_ok means the _outp is allowed to underflow by 1
 254   _outp += at_end_ok;
 255   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 256   _outp -= at_end_ok;
 257   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 258 }
 259 
 260 void DUIterator_Last::verify_limit() {
 261   // Do not require the limit address to be resynched.
 262   //verify(node, true);
 263   assert(_outp == _node->_out, "limit still correct");
 264 }
 265 
 266 void DUIterator_Last::verify_step(uint num_edges) {
 267   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 268   _outcnt   -= num_edges;
 269   _del_tick += num_edges;
 270   // Make sure we are still in sync, possibly with no more out-edges:
 271   const Node* node = _node;
 272   verify(node, true);
 273   assert(node->_last_del == _last, "must have deleted the edge just produced");
 274 }
 275 
 276 #endif //OPTO_DU_ITERATOR_ASSERT
 277 
 278 
 279 #endif //ASSERT
 280 
 281 
 282 // This constant used to initialize _out may be any non-null value.
 283 // The value null is reserved for the top node only.
 284 #define NO_OUT_ARRAY ((Node**)-1)
 285 
 286 // Out-of-line code from node constructors.
 287 // Executed only when extra debug info. is being passed around.
 288 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 289   C->set_node_notes_at(idx, nn);
 290 }
 291 
 292 // Shared initialization code.
 293 inline int Node::Init(int req) {
 294   Compile* C = Compile::current();
 295   int idx = C->next_unique();
 296   NOT_PRODUCT(_igv_idx = C->next_igv_idx());
 297 
 298   // Allocate memory for the necessary number of edges.
 299   if (req > 0) {
 300     // Allocate space for _in array to have double alignment.
 301     _in = (Node **) ((char *) (C->node_arena()->AmallocWords(req * sizeof(void*))));
 302   }
 303   // If there are default notes floating around, capture them:
 304   Node_Notes* nn = C->default_node_notes();
 305   if (nn != nullptr)  init_node_notes(C, idx, nn);
 306 
 307   // Note:  At this point, C is dead,
 308   // and we begin to initialize the new Node.
 309 
 310   _cnt = _max = req;
 311   _outcnt = _outmax = 0;
 312   _class_id = Class_Node;
 313   _flags = 0;
 314   _out = NO_OUT_ARRAY;
 315   return idx;
 316 }
 317 
 318 //------------------------------Node-------------------------------------------
 319 // Create a Node, with a given number of required edges.
 320 Node::Node(uint req)
 321   : _idx(Init(req))
 322 #ifdef ASSERT
 323   , _parse_idx(_idx)
 324 #endif
 325 {
 326   assert( req < Compile::current()->max_node_limit() - NodeLimitFudgeFactor, "Input limit exceeded" );
 327   DEBUG_ONLY( verify_construction() );
 328   NOT_PRODUCT(nodes_created++);
 329   if (req == 0) {
 330     _in = nullptr;
 331   } else {
 332     Node** to = _in;
 333     for(uint i = 0; i < req; i++) {
 334       to[i] = nullptr;
 335     }
 336   }
 337 }
 338 
 339 //------------------------------Node-------------------------------------------
 340 Node::Node(Node *n0)
 341   : _idx(Init(1))
 342 #ifdef ASSERT
 343   , _parse_idx(_idx)
 344 #endif
 345 {
 346   DEBUG_ONLY( verify_construction() );
 347   NOT_PRODUCT(nodes_created++);
 348   assert( is_not_dead(n0), "can not use dead node");
 349   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 350 }
 351 
 352 //------------------------------Node-------------------------------------------
 353 Node::Node(Node *n0, Node *n1)
 354   : _idx(Init(2))
 355 #ifdef ASSERT
 356   , _parse_idx(_idx)
 357 #endif
 358 {
 359   DEBUG_ONLY( verify_construction() );
 360   NOT_PRODUCT(nodes_created++);
 361   assert( is_not_dead(n0), "can not use dead node");
 362   assert( is_not_dead(n1), "can not use dead node");
 363   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 364   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 365 }
 366 
 367 //------------------------------Node-------------------------------------------
 368 Node::Node(Node *n0, Node *n1, Node *n2)
 369   : _idx(Init(3))
 370 #ifdef ASSERT
 371   , _parse_idx(_idx)
 372 #endif
 373 {
 374   DEBUG_ONLY( verify_construction() );
 375   NOT_PRODUCT(nodes_created++);
 376   assert( is_not_dead(n0), "can not use dead node");
 377   assert( is_not_dead(n1), "can not use dead node");
 378   assert( is_not_dead(n2), "can not use dead node");
 379   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 380   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 381   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 382 }
 383 
 384 //------------------------------Node-------------------------------------------
 385 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 386   : _idx(Init(4))
 387 #ifdef ASSERT
 388   , _parse_idx(_idx)
 389 #endif
 390 {
 391   DEBUG_ONLY( verify_construction() );
 392   NOT_PRODUCT(nodes_created++);
 393   assert( is_not_dead(n0), "can not use dead node");
 394   assert( is_not_dead(n1), "can not use dead node");
 395   assert( is_not_dead(n2), "can not use dead node");
 396   assert( is_not_dead(n3), "can not use dead node");
 397   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 398   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 399   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 400   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 401 }
 402 
 403 //------------------------------Node-------------------------------------------
 404 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 405   : _idx(Init(5))
 406 #ifdef ASSERT
 407   , _parse_idx(_idx)
 408 #endif
 409 {
 410   DEBUG_ONLY( verify_construction() );
 411   NOT_PRODUCT(nodes_created++);
 412   assert( is_not_dead(n0), "can not use dead node");
 413   assert( is_not_dead(n1), "can not use dead node");
 414   assert( is_not_dead(n2), "can not use dead node");
 415   assert( is_not_dead(n3), "can not use dead node");
 416   assert( is_not_dead(n4), "can not use dead node");
 417   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 418   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 419   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 420   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 421   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 422 }
 423 
 424 //------------------------------Node-------------------------------------------
 425 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 426                      Node *n4, Node *n5)
 427   : _idx(Init(6))
 428 #ifdef ASSERT
 429   , _parse_idx(_idx)
 430 #endif
 431 {
 432   DEBUG_ONLY( verify_construction() );
 433   NOT_PRODUCT(nodes_created++);
 434   assert( is_not_dead(n0), "can not use dead node");
 435   assert( is_not_dead(n1), "can not use dead node");
 436   assert( is_not_dead(n2), "can not use dead node");
 437   assert( is_not_dead(n3), "can not use dead node");
 438   assert( is_not_dead(n4), "can not use dead node");
 439   assert( is_not_dead(n5), "can not use dead node");
 440   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 441   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 442   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 443   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 444   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 445   _in[5] = n5; if (n5 != nullptr) n5->add_out((Node *)this);
 446 }
 447 
 448 //------------------------------Node-------------------------------------------
 449 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 450                      Node *n4, Node *n5, Node *n6)
 451   : _idx(Init(7))
 452 #ifdef ASSERT
 453   , _parse_idx(_idx)
 454 #endif
 455 {
 456   DEBUG_ONLY( verify_construction() );
 457   NOT_PRODUCT(nodes_created++);
 458   assert( is_not_dead(n0), "can not use dead node");
 459   assert( is_not_dead(n1), "can not use dead node");
 460   assert( is_not_dead(n2), "can not use dead node");
 461   assert( is_not_dead(n3), "can not use dead node");
 462   assert( is_not_dead(n4), "can not use dead node");
 463   assert( is_not_dead(n5), "can not use dead node");
 464   assert( is_not_dead(n6), "can not use dead node");
 465   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 466   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 467   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 468   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 469   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 470   _in[5] = n5; if (n5 != nullptr) n5->add_out((Node *)this);
 471   _in[6] = n6; if (n6 != nullptr) n6->add_out((Node *)this);
 472 }
 473 
 474 #ifdef __clang__
 475 #pragma clang diagnostic pop
 476 #endif
 477 
 478 
 479 //------------------------------clone------------------------------------------
 480 // Clone a Node.
 481 Node *Node::clone() const {
 482   Compile* C = Compile::current();
 483   uint s = size_of();           // Size of inherited Node
 484   Node *n = (Node*)C->node_arena()->AmallocWords(size_of() + _max*sizeof(Node*));
 485   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 486   // Set the new input pointer array
 487   n->_in = (Node**)(((char*)n)+s);
 488   // Cannot share the old output pointer array, so kill it
 489   n->_out = NO_OUT_ARRAY;
 490   // And reset the counters to 0
 491   n->_outcnt = 0;
 492   n->_outmax = 0;
 493   // Unlock this guy, since he is not in any hash table.
 494   DEBUG_ONLY(n->_hash_lock = 0);
 495   // Walk the old node's input list to duplicate its edges
 496   uint i;
 497   for( i = 0; i < len(); i++ ) {
 498     Node *x = in(i);
 499     n->_in[i] = x;
 500     if (x != nullptr) x->add_out(n);
 501   }
 502   if (is_macro()) {
 503     C->add_macro_node(n);
 504   }
 505   if (is_expensive()) {
 506     C->add_expensive_node(n);
 507   }
 508   if (is_ReachabilityFence()) {
 509     C->add_reachability_fence(n->as_ReachabilityFence());
 510   }
 511   if (for_post_loop_opts_igvn()) {
 512     // Don't add cloned node to Compile::_for_post_loop_opts_igvn list automatically.
 513     // If it is applicable, it will happen anyway when the cloned node is registered with IGVN.
 514     n->remove_flag(Node::NodeFlags::Flag_for_post_loop_opts_igvn);
 515   }
 516   if (for_merge_stores_igvn()) {
 517     // Don't add cloned node to Compile::_for_merge_stores_igvn list automatically.
 518     // If it is applicable, it will happen anyway when the cloned node is registered with IGVN.
 519     n->remove_flag(Node::NodeFlags::Flag_for_merge_stores_igvn);
 520   }
 521   if (n->is_ParsePredicate()) {
 522     C->add_parse_predicate(n->as_ParsePredicate());
 523   }
 524   if (n->is_OpaqueTemplateAssertionPredicate()) {
 525     C->add_template_assertion_predicate_opaque(n->as_OpaqueTemplateAssertionPredicate());
 526   }
 527 
 528   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 529   bs->register_potential_barrier_node(n);
 530 
 531   n->set_idx(C->next_unique()); // Get new unique index as well
 532   NOT_PRODUCT(n->_igv_idx = C->next_igv_idx());
 533   DEBUG_ONLY( n->verify_construction() );
 534   NOT_PRODUCT(nodes_created++);
 535   // Do not patch over the debug_idx of a clone, because it makes it
 536   // impossible to break on the clone's moment of creation.
 537   //DEBUG_ONLY( n->set_debug_idx( debug_idx() ) );
 538 
 539   C->copy_node_notes_to(n, (Node*) this);
 540 
 541   // MachNode clone
 542   uint nopnds;
 543   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 544     MachNode *mach  = n->as_Mach();
 545     MachNode *mthis = this->as_Mach();
 546     // Get address of _opnd_array.
 547     // It should be the same offset since it is the clone of this node.
 548     MachOper **from = mthis->_opnds;
 549     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 550                     pointer_delta((const void*)from,
 551                                   (const void*)(&mthis->_opnds), 1));
 552     mach->_opnds = to;
 553     for ( uint i = 0; i < nopnds; ++i ) {
 554       to[i] = from[i]->clone();
 555     }
 556   }
 557   if (this->is_MachProj()) {
 558     // MachProjNodes contain register masks that may contain pointers to
 559     // externally allocated memory. Make sure to use a proper constructor
 560     // instead of just shallowly copying.
 561     MachProjNode* mach = n->as_MachProj();
 562     MachProjNode* mthis = this->as_MachProj();
 563     new (&mach->_rout) RegMask(mthis->_rout);
 564   }
 565   if (n->is_Call()) {
 566     // CallGenerator is linked to the original node.
 567     CallGenerator* cg = n->as_Call()->generator();
 568     if (cg != nullptr) {
 569       CallGenerator* cloned_cg = cg->with_call_node(n->as_Call());
 570       n->as_Call()->set_generator(cloned_cg);
 571     }
 572   }
 573   if (n->is_SafePoint()) {
 574     // Scalar replacement and macro expansion might modify the JVMState.
 575     // Clone it to make sure it's not shared between SafePointNodes.
 576     n->as_SafePoint()->clone_jvms(C);
 577     n->as_SafePoint()->clone_replaced_nodes();
 578   }
 579   if (n->is_InlineType()) {
 580     C->add_inline_type(n);
 581   }
 582   if (n->is_LoadFlat() || n->is_StoreFlat()) {
 583     C->add_flat_access(n);
 584   }
 585   Compile::current()->record_modified_node(n);
 586   return n;                     // Return the clone
 587 }
 588 
 589 //---------------------------setup_is_top--------------------------------------
 590 // Call this when changing the top node, to reassert the invariants
 591 // required by Node::is_top.  See Compile::set_cached_top_node.
 592 void Node::setup_is_top() {
 593   if (this == (Node*)Compile::current()->top()) {
 594     // This node has just become top.  Kill its out array.
 595     _outcnt = _outmax = 0;
 596     _out = nullptr;                           // marker value for top
 597     assert(is_top(), "must be top");
 598   } else {
 599     if (_out == nullptr)  _out = NO_OUT_ARRAY;
 600     assert(!is_top(), "must not be top");
 601   }
 602 }
 603 
 604 //------------------------------~Node------------------------------------------
 605 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 606 void Node::destruct(PhaseValues* phase) {
 607   Compile* compile = (phase != nullptr) ? phase->C : Compile::current();
 608   if (phase != nullptr && phase->is_IterGVN()) {
 609     phase->is_IterGVN()->_worklist.remove(this);
 610   }
 611   // If this is the most recently created node, reclaim its index. Otherwise,
 612   // record the node as dead to keep liveness information accurate.
 613   if ((uint)_idx+1 == compile->unique()) {
 614     compile->set_unique(compile->unique()-1);
 615   } else {
 616     compile->record_dead_node(_idx);
 617   }
 618   // Clear debug info:
 619   Node_Notes* nn = compile->node_notes_at(_idx);
 620   if (nn != nullptr)  nn->clear();
 621   // Walk the input array, freeing the corresponding output edges
 622   _cnt = _max;  // forget req/prec distinction
 623   uint i;
 624   for( i = 0; i < _max; i++ ) {
 625     set_req(i, nullptr);
 626     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 627   }
 628   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 629 
 630   if (is_macro()) {
 631     compile->remove_macro_node(this);
 632   }
 633   if (is_expensive()) {
 634     compile->remove_expensive_node(this);
 635   }
 636   if (is_ReachabilityFence()) {
 637     compile->remove_reachability_fence(as_ReachabilityFence());
 638   }
 639   if (is_OpaqueTemplateAssertionPredicate()) {
 640     compile->remove_template_assertion_predicate_opaque(as_OpaqueTemplateAssertionPredicate());
 641   }
 642   if (is_ParsePredicate()) {
 643     compile->remove_parse_predicate(as_ParsePredicate());
 644   }
 645   if (for_post_loop_opts_igvn()) {
 646     compile->remove_from_post_loop_opts_igvn(this);
 647   }
 648   if (is_InlineType()) {
 649     compile->remove_inline_type(this);
 650   }
 651   if (for_merge_stores_igvn()) {
 652     compile->remove_from_merge_stores_igvn(this);
 653   }
 654 
 655   if (is_SafePoint()) {
 656     as_SafePoint()->delete_replaced_nodes();
 657 
 658     if (is_CallStaticJava()) {
 659       compile->remove_unstable_if_trap(as_CallStaticJava(), false);
 660     }
 661   }
 662   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 663   bs->unregister_potential_barrier_node(this);
 664 
 665   // See if the input array was allocated just prior to the object
 666   int edge_size = _max*sizeof(void*);
 667   int out_edge_size = _outmax*sizeof(void*);
 668   char *in_array = ((char*)_in);
 669   char *edge_end = in_array + edge_size;
 670   char *out_array = (char*)(_out == NO_OUT_ARRAY? nullptr: _out);
 671   int node_size = size_of();
 672 
 673 #ifdef ASSERT
 674   // We will not actually delete the storage, but we'll make the node unusable.
 675   compile->remove_modified_node(this);
 676   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 677   _in = _out = (Node**) badAddress;
 678   _max = _cnt = _outmax = _outcnt = 0;
 679 #endif
 680 
 681   // Free the output edge array
 682   if (out_edge_size > 0) {
 683     compile->node_arena()->Afree(out_array, out_edge_size);
 684   }
 685 
 686   // Free the input edge array and the node itself
 687   if( edge_end == (char*)this ) {
 688     // It was; free the input array and object all in one hit
 689 #ifndef ASSERT
 690     compile->node_arena()->Afree(in_array, edge_size+node_size);
 691 #endif
 692   } else {
 693     // Free just the input array
 694     compile->node_arena()->Afree(in_array, edge_size);
 695 
 696     // Free just the object
 697 #ifndef ASSERT
 698     compile->node_arena()->Afree(this, node_size);
 699 #endif
 700   }
 701 }
 702 
 703 // Resize input or output array to grow it to the next larger power-of-2 bigger
 704 // than len.
 705 void Node::resize_array(Node**& array, node_idx_t& max_size, uint len, bool needs_clearing) {
 706   Arena* arena = Compile::current()->node_arena();
 707   uint new_max = max_size;
 708   if (new_max == 0) {
 709     max_size = 4;
 710     array = (Node**)arena->Amalloc(4 * sizeof(Node*));
 711     if (needs_clearing) {
 712       array[0] = nullptr;
 713       array[1] = nullptr;
 714       array[2] = nullptr;
 715       array[3] = nullptr;
 716     }
 717     return;
 718   }
 719   new_max = next_power_of_2(len);
 720   assert(needs_clearing || (array != nullptr && array != NO_OUT_ARRAY), "out must have sensible value");
 721   array = (Node**)arena->Arealloc(array, max_size * sizeof(Node*), new_max * sizeof(Node*));
 722   if (needs_clearing) {
 723     Copy::zero_to_bytes(&array[max_size], (new_max - max_size) * sizeof(Node*)); // null all new space
 724   }
 725   max_size = new_max;               // Record new max length
 726   // This assertion makes sure that Node::_max is wide enough to
 727   // represent the numerical value of new_max.
 728   assert(max_size > len, "int width of _max or _outmax is too small");
 729 }
 730 
 731 //------------------------------grow-------------------------------------------
 732 // Grow the input array, making space for more edges
 733 void Node::grow(uint len) {
 734   resize_array(_in, _max, len, true);
 735 }
 736 
 737 //-----------------------------out_grow----------------------------------------
 738 // Grow the input array, making space for more edges
 739 void Node::out_grow(uint len) {
 740   assert(!is_top(), "cannot grow a top node's out array");
 741   resize_array(_out, _outmax, len, false);
 742 }
 743 
 744 #ifdef ASSERT
 745 //------------------------------is_dead----------------------------------------
 746 bool Node::is_dead() const {
 747   // Mach and pinch point nodes may look like dead.
 748   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 749     return false;
 750   for( uint i = 0; i < _max; i++ )
 751     if( _in[i] != nullptr )
 752       return false;
 753   return true;
 754 }
 755 
 756 bool Node::is_not_dead(const Node* n) {
 757   return n == nullptr || !PhaseIterGVN::is_verify_def_use() || !(n->is_dead());
 758 }
 759 
 760 bool Node::is_reachable_from_root() const {
 761   ResourceMark rm;
 762   Unique_Node_List wq;
 763   wq.push((Node*)this);
 764   RootNode* root = Compile::current()->root();
 765   for (uint i = 0; i < wq.size(); i++) {
 766     Node* m = wq.at(i);
 767     if (m == root) {
 768       return true;
 769     }
 770     for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
 771       Node* u = m->fast_out(j);
 772       wq.push(u);
 773     }
 774   }
 775   return false;
 776 }
 777 #endif
 778 
 779 //------------------------------is_unreachable---------------------------------
 780 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 781   assert(!is_Mach(), "doesn't work with MachNodes");
 782   return outcnt() == 0 || igvn.type(this) == Type::TOP || (in(0) != nullptr && in(0)->is_top());
 783 }
 784 
 785 //------------------------------add_req----------------------------------------
 786 // Add a new required input at the end
 787 void Node::add_req( Node *n ) {
 788   assert( is_not_dead(n), "can not use dead node");
 789 
 790   // Look to see if I can move precedence down one without reallocating
 791   if( (_cnt >= _max) || (in(_max-1) != nullptr) )
 792     grow( _max+1 );
 793 
 794   // Find a precedence edge to move
 795   if( in(_cnt) != nullptr ) {   // Next precedence edge is busy?
 796     uint i;
 797     for( i=_cnt; i<_max; i++ )
 798       if( in(i) == nullptr )    // Find the null at end of prec edge list
 799         break;                  // There must be one, since we grew the array
 800     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 801   }
 802   _in[_cnt++] = n;            // Stuff over old prec edge
 803   if (n != nullptr) n->add_out((Node *)this);
 804   Compile::current()->record_modified_node(this);
 805 }
 806 
 807 //---------------------------add_req_batch-------------------------------------
 808 // Add a new required input at the end
 809 void Node::add_req_batch( Node *n, uint m ) {
 810   assert( is_not_dead(n), "can not use dead node");
 811   // check various edge cases
 812   if ((int)m <= 1) {
 813     assert((int)m >= 0, "oob");
 814     if (m != 0)  add_req(n);
 815     return;
 816   }
 817 
 818   // Look to see if I can move precedence down one without reallocating
 819   if( (_cnt+m) > _max || _in[_max-m] )
 820     grow( _max+m );
 821 
 822   // Find a precedence edge to move
 823   if( _in[_cnt] != nullptr ) {  // Next precedence edge is busy?
 824     uint i;
 825     for( i=_cnt; i<_max; i++ )
 826       if( _in[i] == nullptr )   // Find the null at end of prec edge list
 827         break;                  // There must be one, since we grew the array
 828     // Slide all the precs over by m positions (assume #prec << m).
 829     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 830   }
 831 
 832   // Stuff over the old prec edges
 833   for(uint i=0; i<m; i++ ) {
 834     _in[_cnt++] = n;
 835   }
 836 
 837   // Insert multiple out edges on the node.
 838   if (n != nullptr && !n->is_top()) {
 839     for(uint i=0; i<m; i++ ) {
 840       n->add_out((Node *)this);
 841     }
 842   }
 843   Compile::current()->record_modified_node(this);
 844 }
 845 
 846 //------------------------------del_req----------------------------------------
 847 // Delete the required edge and compact the edge array
 848 void Node::del_req( uint idx ) {
 849   assert( idx < _cnt, "oob");
 850   assert( !VerifyHashTableKeys || _hash_lock == 0,
 851           "remove node from hash table before modifying it");
 852   // First remove corresponding def-use edge
 853   Node *n = in(idx);
 854   if (n != nullptr) n->del_out((Node *)this);
 855   _in[idx] = in(--_cnt); // Compact the array
 856   // Avoid spec violation: Gap in prec edges.
 857   close_prec_gap_at(_cnt);
 858   Compile::current()->record_modified_node(this);
 859 }
 860 
 861 //------------------------------del_req_ordered--------------------------------
 862 // Delete the required edge and compact the edge array with preserved order
 863 void Node::del_req_ordered( uint idx ) {
 864   assert( idx < _cnt, "oob");
 865   assert( !VerifyHashTableKeys || _hash_lock == 0,
 866           "remove node from hash table before modifying it");
 867   // First remove corresponding def-use edge
 868   Node *n = in(idx);
 869   if (n != nullptr) n->del_out((Node *)this);
 870   if (idx < --_cnt) {    // Not last edge ?
 871     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
 872   }
 873   // Avoid spec violation: Gap in prec edges.
 874   close_prec_gap_at(_cnt);
 875   Compile::current()->record_modified_node(this);
 876 }
 877 
 878 //------------------------------ins_req----------------------------------------
 879 // Insert a new required input at the end
 880 void Node::ins_req( uint idx, Node *n ) {
 881   assert( is_not_dead(n), "can not use dead node");
 882   add_req(nullptr);                // Make space
 883   assert( idx < _max, "Must have allocated enough space");
 884   // Slide over
 885   if(_cnt-idx-1 > 0) {
 886     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 887   }
 888   _in[idx] = n;                            // Stuff over old required edge
 889   if (n != nullptr) n->add_out((Node *)this); // Add reciprocal def-use edge
 890   Compile::current()->record_modified_node(this);
 891 }
 892 
 893 //-----------------------------find_edge---------------------------------------
 894 int Node::find_edge(Node* n) {
 895   for (uint i = 0; i < len(); i++) {
 896     if (_in[i] == n)  return i;
 897   }
 898   return -1;
 899 }
 900 
 901 //----------------------------replace_edge-------------------------------------
 902 int Node::replace_edge(Node* old, Node* neww, PhaseGVN* gvn) {
 903   if (old == neww)  return 0;  // nothing to do
 904   uint nrep = 0;
 905   for (uint i = 0; i < len(); i++) {
 906     if (in(i) == old) {
 907       if (i < req()) {
 908         if (gvn != nullptr) {
 909           set_req_X(i, neww, gvn);
 910         } else {
 911           set_req(i, neww);
 912         }
 913       } else {
 914         assert(gvn == nullptr || gvn->is_IterGVN() == nullptr, "no support for igvn here");
 915         assert(find_prec_edge(neww) == -1, "spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx);
 916         set_prec(i, neww);
 917       }
 918       nrep++;
 919     }
 920   }
 921   return nrep;
 922 }
 923 
 924 /**
 925  * Replace input edges in the range pointing to 'old' node.
 926  */
 927 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end, PhaseGVN* gvn) {
 928   if (old == neww)  return 0;  // nothing to do
 929   uint nrep = 0;
 930   for (int i = start; i < end; i++) {
 931     if (in(i) == old) {
 932       set_req_X(i, neww, gvn);
 933       nrep++;
 934     }
 935   }
 936   return nrep;
 937 }
 938 
 939 //-------------------------disconnect_inputs-----------------------------------
 940 // null out all inputs to eliminate incoming Def-Use edges.
 941 void Node::disconnect_inputs(Compile* C) {
 942   // the layout of Node::_in
 943   // r: a required input, null is allowed
 944   // p: a precedence, null values are all at the end
 945   // -----------------------------------
 946   // |r|...|r|p|...|p|null|...|null|
 947   //         |                     |
 948   //         req()                 len()
 949   // -----------------------------------
 950   for (uint i = 0; i < req(); ++i) {
 951     if (in(i) != nullptr) {
 952       set_req(i, nullptr);
 953     }
 954   }
 955 
 956   // Remove precedence edges if any exist
 957   // Note: Safepoints may have precedence edges, even during parsing
 958   for (uint i = len(); i > req(); ) {
 959     rm_prec(--i);  // no-op if _in[i] is null
 960   }
 961 
 962 #ifdef ASSERT
 963   // sanity check
 964   for (uint i = 0; i < len(); ++i) {
 965     assert(_in[i] == nullptr, "disconnect_inputs() failed!");
 966   }
 967 #endif
 968 
 969   // Node::destruct requires all out edges be deleted first
 970   // DEBUG_ONLY(destruct();)   // no reuse benefit expected
 971   C->record_dead_node(_idx);
 972 }
 973 
 974 //-----------------------------uncast---------------------------------------
 975 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 976 // Strip away casting.  (It is depth-limited.)
 977 // Optionally, keep casts with dependencies.
 978 Node* Node::uncast(bool keep_deps) const {
 979   // Should be inline:
 980   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 981   if (is_ConstraintCast()) {
 982     return uncast_helper(this, keep_deps);
 983   } else {
 984     return (Node*) this;
 985   }
 986 }
 987 
 988 // Find out of current node that matches opcode.
 989 Node* Node::find_out_with(int opcode) {
 990   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 991     Node* use = fast_out(i);
 992     if (use->Opcode() == opcode) {
 993       return use;
 994     }
 995   }
 996   return nullptr;
 997 }
 998 
 999 // Return true if the current node has an out that matches opcode.
1000 bool Node::has_out_with(int opcode) {
1001   return (find_out_with(opcode) != nullptr);
1002 }
1003 
1004 // Return true if the current node has an out that matches any of the opcodes.
1005 bool Node::has_out_with(int opcode1, int opcode2, int opcode3, int opcode4) {
1006   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
1007       int opcode = fast_out(i)->Opcode();
1008       if (opcode == opcode1 || opcode == opcode2 || opcode == opcode3 || opcode == opcode4) {
1009         return true;
1010       }
1011   }
1012   return false;
1013 }
1014 
1015 
1016 //---------------------------uncast_helper-------------------------------------
1017 Node* Node::uncast_helper(const Node* p, bool keep_deps) {
1018 #ifdef ASSERT
1019   // If we end up traversing more nodes than we actually have,
1020   // it is definitely an infinite loop.
1021   uint max_depth = Compile::current()->unique();
1022   uint depth_count = 0;
1023   const Node* orig_p = p;
1024 #endif
1025 
1026   while (true) {
1027 #ifdef ASSERT
1028     if (depth_count++ >= max_depth) {
1029       orig_p->dump(4);
1030       if (p != orig_p) {
1031         p->dump(1);
1032       }
1033       fatal("infinite loop in Node::uncast_helper");
1034     }
1035 #endif
1036     if (p == nullptr || p->req() != 2) {
1037       break;
1038     } else if (p->is_ConstraintCast()) {
1039       if (keep_deps && p->as_ConstraintCast()->carry_dependency()) {
1040         break; // stop at casts with dependencies
1041       }
1042       p = p->in(1);
1043     } else {
1044       break;
1045     }
1046   }
1047   return (Node*) p;
1048 }
1049 
1050 //------------------------------add_prec---------------------------------------
1051 // Add a new precedence input.  Precedence inputs are unordered, with
1052 // duplicates removed and nulls packed down at the end.
1053 void Node::add_prec( Node *n ) {
1054   assert( is_not_dead(n), "can not use dead node");
1055 
1056   // Check for null at end
1057   if( _cnt >= _max || in(_max-1) )
1058     grow( _max+1 );
1059 
1060   // Find a precedence edge to move
1061   uint i = _cnt;
1062   while( in(i) != nullptr ) {
1063     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
1064     i++;
1065   }
1066   _in[i] = n;                                   // Stuff prec edge over null
1067   if ( n != nullptr) n->add_out((Node *)this);  // Add mirror edge
1068 
1069 #ifdef ASSERT
1070   while ((++i)<_max) { assert(_in[i] == nullptr, "spec violation: Gap in prec edges (node %d)", _idx); }
1071 #endif
1072   Compile::current()->record_modified_node(this);
1073 }
1074 
1075 //------------------------------rm_prec----------------------------------------
1076 // Remove a precedence input.  Precedence inputs are unordered, with
1077 // duplicates removed and nulls packed down at the end.
1078 void Node::rm_prec( uint j ) {
1079   assert(j < _max, "oob: i=%d, _max=%d", j, _max);
1080   assert(j >= _cnt, "not a precedence edge");
1081   if (_in[j] == nullptr) return;   // Avoid spec violation: Gap in prec edges.
1082   _in[j]->del_out((Node *)this);
1083   close_prec_gap_at(j);
1084   Compile::current()->record_modified_node(this);
1085 }
1086 
1087 //------------------------------size_of----------------------------------------
1088 uint Node::size_of() const { return sizeof(*this); }
1089 
1090 //------------------------------ideal_reg--------------------------------------
1091 uint Node::ideal_reg() const { return 0; }
1092 
1093 //------------------------------jvms-------------------------------------------
1094 JVMState* Node::jvms() const { return nullptr; }
1095 
1096 #ifdef ASSERT
1097 //------------------------------jvms-------------------------------------------
1098 bool Node::verify_jvms(const JVMState* using_jvms) const {
1099   for (JVMState* jvms = this->jvms(); jvms != nullptr; jvms = jvms->caller()) {
1100     if (jvms == using_jvms)  return true;
1101   }
1102   return false;
1103 }
1104 
1105 //------------------------------init_NodeProperty------------------------------
1106 void Node::init_NodeProperty() {
1107   assert(_max_classes <= max_juint, "too many NodeProperty classes");
1108   assert(max_flags() <= max_juint, "too many NodeProperty flags");
1109 }
1110 
1111 //-----------------------------max_flags---------------------------------------
1112 juint Node::max_flags() {
1113   return (PD::_last_flag << 1) - 1; // allow flags combination
1114 }
1115 #endif
1116 
1117 //------------------------------format-----------------------------------------
1118 // Print as assembly
1119 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1120 //------------------------------emit-------------------------------------------
1121 // Emit bytes using C2_MacroAssembler
1122 void Node::emit(C2_MacroAssembler *masm, PhaseRegAlloc *ra_) const {}
1123 //------------------------------size-------------------------------------------
1124 // Size of instruction in bytes
1125 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1126 
1127 //------------------------------CFG Construction-------------------------------
1128 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1129 // Goto and Return.
1130 const Node *Node::is_block_proj() const { return nullptr; }
1131 
1132 // Minimum guaranteed type
1133 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1134 
1135 
1136 //------------------------------raise_bottom_type------------------------------
1137 // Get the worst-case Type output for this Node.
1138 void Node::raise_bottom_type(const Type* new_type) {
1139   if (is_Type()) {
1140     TypeNode *n = this->as_Type();
1141     if (VerifyAliases) {
1142       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1143     }
1144     n->set_type(new_type);
1145   } else if (is_Load()) {
1146     LoadNode *n = this->as_Load();
1147     if (VerifyAliases) {
1148       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1149     }
1150     n->set_type(new_type);
1151   }
1152 }
1153 
1154 //------------------------------Identity---------------------------------------
1155 // Return a node that the given node is equivalent to.
1156 Node* Node::Identity(PhaseGVN* phase) {
1157   return this;                  // Default to no identities
1158 }
1159 
1160 //------------------------------Value------------------------------------------
1161 // Compute a new Type for a node using the Type of the inputs.
1162 const Type* Node::Value(PhaseGVN* phase) const {
1163   return bottom_type();         // Default to worst-case Type
1164 }
1165 
1166 //------------------------------Ideal------------------------------------------
1167 //
1168 // 'Idealize' the graph rooted at this Node.
1169 //
1170 // In order to be efficient and flexible there are some subtle invariants
1171 // these Ideal calls need to hold. Some of the flag bits for '-XX:VerifyIterativeGVN'
1172 // can help with validating these invariants, although they are too slow to have on by default:
1173 //    - '-XX:VerifyIterativeGVN=1' checks the def-use info
1174 //    - '-XX:VerifyIterativeGVN=100000' checks the return value
1175 // If you are hacking an Ideal call, be sure to use these.
1176 //
1177 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1178 // pointer.  If ANY change is made, it must return the root of the reshaped
1179 // graph - even if the root is the same Node.  Example: swapping the inputs
1180 // to an AddINode gives the same answer and same root, but you still have to
1181 // return the 'this' pointer instead of null. If the node was already dead
1182 // before the Ideal call, this rule does not apply, and it is fine to return
1183 // nullptr even if modifications were made.
1184 //
1185 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1186 // Identity call to return an old Node; basically if Identity can find
1187 // another Node have the Ideal call make no change and return null.
1188 // Example: AddINode::Ideal must check for add of zero; in this case it
1189 // returns null instead of doing any graph reshaping.
1190 //
1191 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1192 // sharing there may be other users of the old Nodes relying on their current
1193 // semantics.  Modifying them will break the other users.
1194 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1195 // "X+3" unchanged in case it is shared.
1196 //
1197 // If you modify the 'this' pointer's inputs, you should use
1198 // 'set_req'.  If you are making a new Node (either as the new root or
1199 // some new internal piece) you may use 'init_req' to set the initial
1200 // value.  You can make a new Node with either 'new' or 'clone'.  In
1201 // either case, def-use info is correctly maintained.
1202 //
1203 // Example: reshape "(X+3)+4" into "X+7":
1204 //    set_req(1, in(1)->in(1));
1205 //    set_req(2, phase->intcon(7));
1206 //    return this;
1207 // Example: reshape "X*4" into "X<<2"
1208 //    return new LShiftINode(in(1), phase->intcon(2));
1209 //
1210 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1211 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1212 //    Node *shift=phase->transform(new LShiftINode(in(1),phase->intcon(5)));
1213 //    return new AddINode(shift, in(1));
1214 //
1215 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1216 // These forms are faster than 'phase->transform(new ConNode())' and Do
1217 // The Right Thing with def-use info.
1218 //
1219 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1220 // graph uses the 'this' Node it must be the root.  If you want a Node with
1221 // the same Opcode as the 'this' pointer use 'clone'.
1222 //
1223 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1224   return nullptr;                  // Default to being Ideal already
1225 }
1226 
1227 // Some nodes have specific Ideal subgraph transformations only if they are
1228 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1229 // for the transformations to happen.
1230 bool Node::has_special_unique_user() const {
1231   assert(outcnt() == 1, "match only for unique out");
1232   Node* n = unique_out();
1233   int op  = Opcode();
1234   if (this->is_Store()) {
1235     // Condition for back-to-back stores folding.
1236     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1237   } else if ((this->is_Load() || this->is_DecodeN() || this->is_Phi() || this->is_Con()) && n->Opcode() == Op_MemBarAcquire) {
1238     // Condition for removing an unused LoadNode or DecodeNNode from the MemBarAcquire precedence input
1239     return true;
1240   } else if (this->is_Load() && n->is_Move()) {
1241     // Condition for MoveX2Y (LoadX mem) => LoadY mem
1242     return true;
1243   } else if (op == Op_AddL) {
1244     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1245     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1246   } else if (op == Op_SubI || op == Op_SubL) {
1247     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1248     return n->Opcode() == op && n->in(2) == this;
1249   } else if (is_If() && (n->is_IfFalse() || n->is_IfTrue())) {
1250     // See IfProjNode::Identity()
1251     return true;
1252   } else if ((is_IfFalse() || is_IfTrue()) && n->is_If()) {
1253     // See IfNode::fold_compares
1254     return true;
1255   } else if (n->Opcode() == Op_XorV || n->Opcode() == Op_XorVMask) {
1256     // Condition for XorVMask(VectorMaskCmp(x,y,cond), MaskAll(true)) ==> VectorMaskCmp(x,y,ncond)
1257     return true;
1258   } else {
1259     return false;
1260   }
1261 };
1262 
1263 //--------------------------find_exact_control---------------------------------
1264 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1265 Node* Node::find_exact_control(Node* ctrl) {
1266   if (ctrl == nullptr && this->is_Region())
1267     ctrl = this->as_Region()->is_copy();
1268 
1269   if (ctrl != nullptr && ctrl->is_CatchProj()) {
1270     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1271       ctrl = ctrl->in(0);
1272     if (ctrl != nullptr && !ctrl->is_top())
1273       ctrl = ctrl->in(0);
1274   }
1275 
1276   if (ctrl != nullptr && ctrl->is_Proj())
1277     ctrl = ctrl->in(0);
1278 
1279   return ctrl;
1280 }
1281 
1282 //--------------------------dominates------------------------------------------
1283 // Helper function for MemNode::all_controls_dominate().
1284 // Check if 'this' control node dominates or equal to 'sub' control node.
1285 // We already know that if any path back to Root or Start reaches 'this',
1286 // then all paths so, so this is a simple search for one example,
1287 // not an exhaustive search for a counterexample.
1288 Node::DomResult Node::dominates(Node* sub, Node_List &nlist) {
1289   assert(this->is_CFG(), "expecting control");
1290   assert(sub != nullptr && sub->is_CFG(), "expecting control");
1291 
1292   // detect dead cycle without regions
1293   int iterations_without_region_limit = DominatorSearchLimit;
1294 
1295   Node* orig_sub = sub;
1296   Node* dom      = this;
1297   bool  met_dom  = false;
1298   nlist.clear();
1299 
1300   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1301   // After seeing 'dom', continue up to Root or Start.
1302   // If we hit a region (backward split point), it may be a loop head.
1303   // Keep going through one of the region's inputs.  If we reach the
1304   // same region again, go through a different input.  Eventually we
1305   // will either exit through the loop head, or give up.
1306   // (If we get confused, break out and return a conservative 'false'.)
1307   while (sub != nullptr) {
1308     if (sub->is_top()) {
1309       // Conservative answer for dead code.
1310       return DomResult::EncounteredDeadCode;
1311     }
1312     if (sub == dom) {
1313       if (nlist.size() == 0) {
1314         // No Region nodes except loops were visited before and the EntryControl
1315         // path was taken for loops: it did not walk in a cycle.
1316         return DomResult::Dominate;
1317       } else if (met_dom) {
1318         break;          // already met before: walk in a cycle
1319       } else {
1320         // Region nodes were visited. Continue walk up to Start or Root
1321         // to make sure that it did not walk in a cycle.
1322         met_dom = true; // first time meet
1323         iterations_without_region_limit = DominatorSearchLimit; // Reset
1324      }
1325     }
1326     if (sub->is_Start() || sub->is_Root()) {
1327       // Success if we met 'dom' along a path to Start or Root.
1328       // We assume there are no alternative paths that avoid 'dom'.
1329       // (This assumption is up to the caller to ensure!)
1330       return met_dom ? DomResult::Dominate : DomResult::NotDominate;
1331     }
1332     Node* up = sub->in(0);
1333     // Normalize simple pass-through regions and projections:
1334     up = sub->find_exact_control(up);
1335     // If sub == up, we found a self-loop.  Try to push past it.
1336     if (sub == up && sub->is_Loop()) {
1337       // Take loop entry path on the way up to 'dom'.
1338       up = sub->in(1); // in(LoopNode::EntryControl);
1339     } else if (sub == up && sub->is_Region() && sub->req() == 2) {
1340       // Take in(1) path on the way up to 'dom' for regions with only one input
1341       up = sub->in(1);
1342     } else if (sub == up && sub->is_Region()) {
1343       // Try both paths for Regions with 2 input paths (it may be a loop head).
1344       // It could give conservative 'false' answer without information
1345       // which region's input is the entry path.
1346       iterations_without_region_limit = DominatorSearchLimit; // Reset
1347 
1348       bool region_was_visited_before = false;
1349       // Was this Region node visited before?
1350       // If so, we have reached it because we accidentally took a
1351       // loop-back edge from 'sub' back into the body of the loop,
1352       // and worked our way up again to the loop header 'sub'.
1353       // So, take the first unexplored path on the way up to 'dom'.
1354       for (int j = nlist.size() - 1; j >= 0; j--) {
1355         intptr_t ni = (intptr_t)nlist.at(j);
1356         Node* visited = (Node*)(ni & ~1);
1357         bool  visited_twice_already = ((ni & 1) != 0);
1358         if (visited == sub) {
1359           if (visited_twice_already) {
1360             // Visited 2 paths, but still stuck in loop body.  Give up.
1361             return DomResult::NotDominate;
1362           }
1363           // The Region node was visited before only once.
1364           // (We will repush with the low bit set, below.)
1365           nlist.remove(j);
1366           // We will find a new edge and re-insert.
1367           region_was_visited_before = true;
1368           break;
1369         }
1370       }
1371 
1372       // Find an incoming edge which has not been seen yet; walk through it.
1373       assert(up == sub, "");
1374       uint skip = region_was_visited_before ? 1 : 0;
1375       for (uint i = 1; i < sub->req(); i++) {
1376         Node* in = sub->in(i);
1377         if (in != nullptr && !in->is_top() && in != sub) {
1378           if (skip == 0) {
1379             up = in;
1380             break;
1381           }
1382           --skip;               // skip this nontrivial input
1383         }
1384       }
1385 
1386       // Set 0 bit to indicate that both paths were taken.
1387       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1388     }
1389 
1390     if (up == sub) {
1391       break;    // some kind of tight cycle
1392     }
1393     if (up == orig_sub && met_dom) {
1394       // returned back after visiting 'dom'
1395       break;    // some kind of cycle
1396     }
1397     if (--iterations_without_region_limit < 0) {
1398       break;    // dead cycle
1399     }
1400     sub = up;
1401   }
1402 
1403   // Did not meet Root or Start node in pred. chain.
1404   return DomResult::NotDominate;
1405 }
1406 
1407 //------------------------------remove_dead_region-----------------------------
1408 // This control node is dead.  Follow the subgraph below it making everything
1409 // using it dead as well.  This will happen normally via the usual IterGVN
1410 // worklist but this call is more efficient.  Do not update use-def info
1411 // inside the dead region, just at the borders.
1412 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1413   // Con's are a popular node to re-hit in the hash table again.
1414   if( dead->is_Con() ) return;
1415 
1416   ResourceMark rm;
1417   Node_List nstack;
1418   VectorSet dead_set; // notify uses only once
1419 
1420   Node *top = igvn->C->top();
1421   nstack.push(dead);
1422   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1423 
1424   while (nstack.size() > 0) {
1425     dead = nstack.pop();
1426     if (!dead_set.test_set(dead->_idx)) {
1427       // If dead has any live uses, those are now still attached. Notify them before we lose them.
1428       igvn->add_users_to_worklist(dead);
1429     }
1430     if (dead->Opcode() == Op_SafePoint) {
1431       dead->as_SafePoint()->disconnect_from_root(igvn);
1432     }
1433     if (dead->outcnt() > 0) {
1434       // Keep dead node on stack until all uses are processed.
1435       nstack.push(dead);
1436       // For all Users of the Dead...    ;-)
1437       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1438         Node* use = dead->last_out(k);
1439         igvn->hash_delete(use);       // Yank from hash table prior to mod
1440         if (use->in(0) == dead) {     // Found another dead node
1441           assert (!use->is_Con(), "Control for Con node should be Root node.");
1442           use->set_req(0, top);       // Cut dead edge to prevent processing
1443           nstack.push(use);           // the dead node again.
1444         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1445                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1446                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1447           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1448           use->set_req(0, top);       // Cut self edge
1449           nstack.push(use);
1450         } else {                      // Else found a not-dead user
1451           // Dead if all inputs are top or null
1452           bool dead_use = !use->is_Root(); // Keep empty graph alive
1453           for (uint j = 1; j < use->req(); j++) {
1454             Node* in = use->in(j);
1455             if (in == dead) {         // Turn all dead inputs into TOP
1456               use->set_req(j, top);
1457             } else if (in != nullptr && !in->is_top()) {
1458               dead_use = false;
1459             }
1460           }
1461           if (dead_use) {
1462             if (use->is_Region()) {
1463               use->set_req(0, top);   // Cut self edge
1464             }
1465             nstack.push(use);
1466           } else {
1467             igvn->_worklist.push(use);
1468           }
1469         }
1470         // Refresh the iterator, since any number of kills might have happened.
1471         k = dead->last_outs(kmin);
1472       }
1473     } else { // (dead->outcnt() == 0)
1474       // Done with outputs.
1475       igvn->hash_delete(dead);
1476       igvn->_worklist.remove(dead);
1477       igvn->set_type(dead, Type::TOP);
1478       // Kill all inputs to the dead guy
1479       for (uint i=0; i < dead->req(); i++) {
1480         Node *n = dead->in(i);      // Get input to dead guy
1481         if (n != nullptr && !n->is_top()) { // Input is valid?
1482           dead->set_req(i, top);    // Smash input away
1483           if (n->outcnt() == 0) {   // Input also goes dead?
1484             if (!n->is_Con())
1485               nstack.push(n);       // Clear it out as well
1486           } else if (n->outcnt() == 1 &&
1487                      n->has_special_unique_user()) {
1488             igvn->add_users_to_worklist( n );
1489           } else if (n->outcnt() <= 2 && n->is_Store()) {
1490             // Push store's uses on worklist to enable folding optimization for
1491             // store/store and store/load to the same address.
1492             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1493             // and remove_globally_dead_node().
1494             igvn->add_users_to_worklist( n );
1495           } else if (dead->is_data_proj_of_pure_function(n)) {
1496             igvn->_worklist.push(n);
1497           } else {
1498             BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, n);
1499           }
1500         }
1501       }
1502       igvn->C->remove_useless_node(dead);
1503     } // (dead->outcnt() == 0)
1504   }   // while (nstack.size() > 0) for outputs
1505   return;
1506 }
1507 
1508 //------------------------------remove_dead_region-----------------------------
1509 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1510   Node *n = in(0);
1511   if( !n ) return false;
1512   // Lost control into this guy?  I.e., it became unreachable?
1513   // Aggressively kill all unreachable code.
1514   if (can_reshape && n->is_top()) {
1515     kill_dead_code(this, phase->is_IterGVN());
1516     return false; // Node is dead.
1517   }
1518 
1519   if( n->is_Region() && n->as_Region()->is_copy() ) {
1520     Node *m = n->nonnull_req();
1521     set_req(0, m);
1522     return true;
1523   }
1524   return false;
1525 }
1526 
1527 //------------------------------hash-------------------------------------------
1528 // Hash function over Nodes.
1529 uint Node::hash() const {
1530   uint sum = 0;
1531   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1532     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded nulls
1533   return (sum>>2) + _cnt + Opcode();
1534 }
1535 
1536 //------------------------------cmp--------------------------------------------
1537 // Compare special parts of simple Nodes
1538 bool Node::cmp( const Node &n ) const {
1539   return true;                  // Must be same
1540 }
1541 
1542 //------------------------------rematerialize-----------------------------------
1543 // Should we clone rather than spill this instruction?
1544 bool Node::rematerialize() const {
1545   if ( is_Mach() )
1546     return this->as_Mach()->rematerialize();
1547   else
1548     return (_flags & Flag_rematerialize) != 0;
1549 }
1550 
1551 //------------------------------needs_anti_dependence_check---------------------
1552 // Nodes which use memory without consuming it, hence need antidependences.
1553 bool Node::needs_anti_dependence_check() const {
1554   if (req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0) {
1555     return false;
1556   }
1557   return in(1)->bottom_type()->has_memory();
1558 }
1559 
1560 // Get an integer constant from a ConNode (or CastIINode).
1561 // Return a default value if there is no apparent constant here.
1562 const TypeInt* Node::find_int_type() const {
1563   if (this->is_Type()) {
1564     return this->as_Type()->type()->isa_int();
1565   } else if (this->is_Con()) {
1566     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1567     return this->bottom_type()->isa_int();
1568   }
1569   return nullptr;
1570 }
1571 
1572 const TypeInteger* Node::find_integer_type(BasicType bt) const {
1573   if (this->is_Type()) {
1574     return this->as_Type()->type()->isa_integer(bt);
1575   } else if (this->is_Con()) {
1576     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1577     return this->bottom_type()->isa_integer(bt);
1578   }
1579   return nullptr;
1580 }
1581 
1582 // Get a pointer constant from a ConstNode.
1583 // Returns the constant if it is a pointer ConstNode
1584 intptr_t Node::get_ptr() const {
1585   assert( Opcode() == Op_ConP, "" );
1586   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1587 }
1588 
1589 // Get a narrow oop constant from a ConNNode.
1590 intptr_t Node::get_narrowcon() const {
1591   assert( Opcode() == Op_ConN, "" );
1592   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1593 }
1594 
1595 // Get a long constant from a ConNode.
1596 // Return a default value if there is no apparent constant here.
1597 const TypeLong* Node::find_long_type() const {
1598   if (this->is_Type()) {
1599     return this->as_Type()->type()->isa_long();
1600   } else if (this->is_Con()) {
1601     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1602     return this->bottom_type()->isa_long();
1603   }
1604   return nullptr;
1605 }
1606 
1607 
1608 /**
1609  * Return a ptr type for nodes which should have it.
1610  */
1611 const TypePtr* Node::get_ptr_type() const {
1612   const TypePtr* tp = this->bottom_type()->make_ptr();
1613 #ifdef ASSERT
1614   if (tp == nullptr) {
1615     this->dump(1);
1616     assert((tp != nullptr), "unexpected node type");
1617   }
1618 #endif
1619   return tp;
1620 }
1621 
1622 // Get a double constant from a ConstNode.
1623 // Returns the constant if it is a double ConstNode
1624 jdouble Node::getd() const {
1625   assert( Opcode() == Op_ConD, "" );
1626   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1627 }
1628 
1629 // Get a float constant from a ConstNode.
1630 // Returns the constant if it is a float ConstNode
1631 jfloat Node::getf() const {
1632   assert( Opcode() == Op_ConF, "" );
1633   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1634 }
1635 
1636 // Get a half float constant from a ConstNode.
1637 // Returns the constant if it is a float ConstNode
1638 jshort Node::geth() const {
1639   assert( Opcode() == Op_ConH, "" );
1640   return ((ConHNode*)this)->type()->is_half_float_constant()->geth();
1641 }
1642 
1643 #ifndef PRODUCT
1644 
1645 // Call this from debugger:
1646 Node* old_root() {
1647   Matcher* matcher = Compile::current()->matcher();
1648   if (matcher != nullptr) {
1649     Node* new_root = Compile::current()->root();
1650     Node* old_root = matcher->find_old_node(new_root);
1651     if (old_root != nullptr) {
1652       return old_root;
1653     }
1654   }
1655   tty->print("old_root: not found.\n");
1656   return nullptr;
1657 }
1658 
1659 // BFS traverse all reachable nodes from start, call callback on them
1660 template <typename Callback>
1661 void visit_nodes(Node* start, Callback callback, bool traverse_output, bool only_ctrl) {
1662   Unique_Mixed_Node_List worklist;
1663   worklist.add(start);
1664   for (uint i = 0; i < worklist.size(); i++) {
1665     Node* n = worklist[i];
1666     callback(n);
1667     for (uint i = 0; i < n->len(); i++) {
1668       if (!only_ctrl || n->is_Region() || (n->Opcode() == Op_Root) || (i == TypeFunc::Control)) {
1669         // If only_ctrl is set: Add regions, the root node, or control inputs only
1670         worklist.add(n->in(i));
1671       }
1672     }
1673     if (traverse_output && !only_ctrl) {
1674       for (uint i = 0; i < n->outcnt(); i++) {
1675         worklist.add(n->raw_out(i));
1676       }
1677     }
1678   }
1679 }
1680 
1681 // BFS traverse from start, return node with idx
1682 static Node* find_node_by_idx(Node* start, uint idx, bool traverse_output, bool only_ctrl) {
1683   ResourceMark rm;
1684   Node* result = nullptr;
1685   auto callback = [&] (Node* n) {
1686     if (n->_idx == idx) {
1687       if (result != nullptr) {
1688         tty->print("find_node_by_idx: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1689           (uintptr_t)result, (uintptr_t)n, idx);
1690       }
1691       result = n;
1692     }
1693   };
1694   visit_nodes(start, callback, traverse_output, only_ctrl);
1695   return result;
1696 }
1697 
1698 static int node_idx_cmp(const Node** n1, const Node** n2) {
1699   return (*n1)->_idx - (*n2)->_idx;
1700 }
1701 
1702 static void find_nodes_by_name(Node* start, const char* name) {
1703   ResourceMark rm;
1704   GrowableArray<const Node*> ns;
1705   auto callback = [&] (const Node* n) {
1706     if (StringUtils::is_star_match(name, n->Name())) {
1707       ns.push(n);
1708     }
1709   };
1710   visit_nodes(start, callback, true, false);
1711   ns.sort(node_idx_cmp);
1712   for (int i = 0; i < ns.length(); i++) {
1713     ns.at(i)->dump();
1714   }
1715 }
1716 
1717 static void find_nodes_by_dump(Node* start, const char* pattern) {
1718   ResourceMark rm;
1719   GrowableArray<const Node*> ns;
1720   auto callback = [&] (const Node* n) {
1721     stringStream stream;
1722     n->dump("", false, &stream);
1723     if (StringUtils::is_star_match(pattern, stream.base())) {
1724       ns.push(n);
1725     }
1726   };
1727   visit_nodes(start, callback, true, false);
1728   ns.sort(node_idx_cmp);
1729   for (int i = 0; i < ns.length(); i++) {
1730     ns.at(i)->dump();
1731   }
1732 }
1733 
1734 // call from debugger: find node with name pattern in new/current graph
1735 // name can contain "*" in match pattern to match any characters
1736 // the matching is case insensitive
1737 void find_nodes_by_name(const char* name) {
1738   Node* root = Compile::current()->root();
1739   find_nodes_by_name(root, name);
1740 }
1741 
1742 // call from debugger: find node with name pattern in old graph
1743 // name can contain "*" in match pattern to match any characters
1744 // the matching is case insensitive
1745 void find_old_nodes_by_name(const char* name) {
1746   Node* root = old_root();
1747   find_nodes_by_name(root, name);
1748 }
1749 
1750 // call from debugger: find node with dump pattern in new/current graph
1751 // can contain "*" in match pattern to match any characters
1752 // the matching is case insensitive
1753 void find_nodes_by_dump(const char* pattern) {
1754   Node* root = Compile::current()->root();
1755   find_nodes_by_dump(root, pattern);
1756 }
1757 
1758 // call from debugger: find node with name pattern in old graph
1759 // can contain "*" in match pattern to match any characters
1760 // the matching is case insensitive
1761 void find_old_nodes_by_dump(const char* pattern) {
1762   Node* root = old_root();
1763   find_nodes_by_dump(root, pattern);
1764 }
1765 
1766 // Call this from debugger, search in same graph as n:
1767 Node* find_node(Node* n, const int idx) {
1768   return n->find(idx);
1769 }
1770 
1771 // Call this from debugger, search in new nodes:
1772 Node* find_node(const int idx) {
1773   return Compile::current()->root()->find(idx);
1774 }
1775 
1776 // Call this from debugger, search in old nodes:
1777 Node* find_old_node(const int idx) {
1778   Node* root = old_root();
1779   return (root == nullptr) ? nullptr : root->find(idx);
1780 }
1781 
1782 // Call this from debugger, search in same graph as n:
1783 Node* find_ctrl(Node* n, const int idx) {
1784   return n->find_ctrl(idx);
1785 }
1786 
1787 // Call this from debugger, search in new nodes:
1788 Node* find_ctrl(const int idx) {
1789   return Compile::current()->root()->find_ctrl(idx);
1790 }
1791 
1792 // Call this from debugger, search in old nodes:
1793 Node* find_old_ctrl(const int idx) {
1794   Node* root = old_root();
1795   return (root == nullptr) ? nullptr : root->find_ctrl(idx);
1796 }
1797 
1798 //------------------------------find_ctrl--------------------------------------
1799 // Find an ancestor to this node in the control history with given _idx
1800 Node* Node::find_ctrl(int idx) {
1801   return find(idx, true);
1802 }
1803 
1804 //------------------------------find-------------------------------------------
1805 // Tries to find the node with the index |idx| starting from this node. If idx is negative,
1806 // the search also includes forward (out) edges. Returns null if not found.
1807 // If only_ctrl is set, the search will only be done on control nodes. Returns null if
1808 // not found or if the node to be found is not a control node (search will not find it).
1809 Node* Node::find(const int idx, bool only_ctrl) {
1810   ResourceMark rm;
1811   return find_node_by_idx(this, abs(idx), (idx < 0), only_ctrl);
1812 }
1813 
1814 class PrintBFS {
1815 public:
1816   PrintBFS(const Node* start, const int max_distance, const Node* target, const char* options, outputStream* st, const frame* fr)
1817     : _start(start), _max_distance(max_distance), _target(target), _options(options), _output(st), _frame(fr),
1818     _dcc(this), _info_uid(cmpkey, hashkey) {}
1819 
1820   void run();
1821 private:
1822   // pipeline steps
1823   bool configure();
1824   void collect();
1825   void select();
1826   void select_all();
1827   void select_all_paths();
1828   void select_shortest_path();
1829   void sort();
1830   void print();
1831 
1832   // inputs
1833   const Node* _start;
1834   const int _max_distance;
1835   const Node* _target;
1836   const char* _options;
1837   outputStream* _output;
1838   const frame* _frame;
1839 
1840   // options
1841   bool _traverse_inputs = false;
1842   bool _traverse_outputs = false;
1843   struct Filter {
1844     bool _control = false;
1845     bool _memory = false;
1846     bool _data = false;
1847     bool _mixed = false;
1848     bool _other = false;
1849     bool is_empty() const {
1850       return !(_control || _memory || _data || _mixed || _other);
1851     }
1852     void set_all() {
1853       _control = true;
1854       _memory = true;
1855       _data = true;
1856       _mixed = true;
1857       _other = true;
1858     }
1859     // Check if the filter accepts the node. Go by the type categories, but also all CFG nodes
1860     // are considered to have control.
1861     bool accepts(const Node* n) {
1862       const Type* t = n->bottom_type();
1863       return ( _data    &&  t->has_category(Type::Category::Data)                    ) ||
1864              ( _memory  &&  t->has_category(Type::Category::Memory)                  ) ||
1865              ( _mixed   &&  t->has_category(Type::Category::Mixed)                   ) ||
1866              ( _control && (t->has_category(Type::Category::Control) || n->is_CFG()) ) ||
1867              ( _other   &&  t->has_category(Type::Category::Other)                   );
1868     }
1869   };
1870   Filter _filter_visit;
1871   Filter _filter_boundary;
1872   bool _sort_idx = false;
1873   bool _all_paths = false;
1874   bool _use_color = false;
1875   bool _print_blocks = false;
1876   bool _print_old = false;
1877   bool _dump_only = false;
1878   bool _print_igv = false;
1879 
1880   void print_options_help(bool print_examples);
1881   bool parse_options();
1882 
1883 public:
1884   class DumpConfigColored : public Node::DumpConfig {
1885   public:
1886     DumpConfigColored(PrintBFS* bfs) : _bfs(bfs) {};
1887     virtual void pre_dump(outputStream* st, const Node* n);
1888     virtual void post_dump(outputStream* st);
1889   private:
1890     PrintBFS* _bfs;
1891   };
1892 private:
1893   DumpConfigColored _dcc;
1894 
1895   // node info
1896   static Node* old_node(const Node* n); // mach node -> prior IR node
1897   void print_node_idx(const Node* n);
1898   void print_block_id(const Block* b);
1899   void print_node_block(const Node* n); // _pre_order, head idx, _idom, _dom_depth
1900 
1901   // traversal data structures
1902   GrowableArray<const Node*> _worklist; // BFS queue
1903   void maybe_traverse(const Node* src, const Node* dst);
1904 
1905   // node info annotation
1906   class Info {
1907   public:
1908     Info() : Info(nullptr, 0) {};
1909     Info(const Node* node, int distance)
1910       : _node(node), _distance_from_start(distance) {};
1911     const Node* node() const { return _node; };
1912     int distance() const { return _distance_from_start; };
1913     int distance_from_target() const { return _distance_from_target; }
1914     void set_distance_from_target(int d) { _distance_from_target = d; }
1915     GrowableArray<const Node*> edge_bwd; // pointing toward _start
1916     bool is_marked() const { return _mark; } // marked to keep during select
1917     void set_mark() { _mark = true; }
1918   private:
1919     const Node* _node;
1920     int _distance_from_start; // distance from _start
1921     int _distance_from_target = 0; // distance from _target if _all_paths
1922     bool _mark = false;
1923   };
1924   Dict _info_uid;            // Node -> uid
1925   GrowableArray<Info> _info; // uid  -> info
1926 
1927   Info* find_info(const Node* n) {
1928     size_t uid = (size_t)_info_uid[n];
1929     if (uid == 0) {
1930       return nullptr;
1931     }
1932     return &_info.at((int)uid);
1933   }
1934 
1935   void make_info(const Node* node, const int distance) {
1936     assert(find_info(node) == nullptr, "node does not yet have info");
1937     size_t uid = _info.length() + 1;
1938     _info_uid.Insert((void*)node, (void*)uid);
1939     _info.at_put_grow((int)uid, Info(node, distance));
1940     assert(find_info(node)->node() == node, "stored correct node");
1941   };
1942 
1943   // filled by sort, printed by print
1944   GrowableArray<const Node*> _print_list;
1945 
1946   // print header + node table
1947   void print_header() const;
1948   void print_node(const Node* n);
1949 };
1950 
1951 void PrintBFS::run() {
1952   if (!configure()) {
1953     return;
1954   }
1955   collect();
1956   select();
1957   sort();
1958   print();
1959 }
1960 
1961 // set up configuration for BFS and print
1962 bool PrintBFS::configure() {
1963   if (_max_distance < 0) {
1964     _output->print_cr("dump_bfs: max_distance must be non-negative!");
1965     return false;
1966   }
1967   return parse_options();
1968 }
1969 
1970 // BFS traverse according to configuration, fill worklist and info
1971 void PrintBFS::collect() {
1972   maybe_traverse(_start, _start);
1973   int pos = 0;
1974   while (pos < _worklist.length()) {
1975     const Node* n = _worklist.at(pos++); // next node to traverse
1976     Info* info = find_info(n);
1977     if (!_filter_visit.accepts(n) && n != _start) {
1978       continue; // we hit boundary, do not traverse further
1979     }
1980     if (n != _start && n->is_Root()) {
1981       continue; // traversing through root node would lead to unrelated nodes
1982     }
1983     if (_traverse_inputs && _max_distance > info->distance()) {
1984       for (uint i = 0; i < n->req(); i++) {
1985         maybe_traverse(n, n->in(i));
1986       }
1987     }
1988     if (_traverse_outputs && _max_distance > info->distance()) {
1989       for (uint i = 0; i < n->outcnt(); i++) {
1990         maybe_traverse(n, n->raw_out(i));
1991       }
1992     }
1993   }
1994 }
1995 
1996 // go through work list, mark those that we want to print
1997 void PrintBFS::select() {
1998   if (_target == nullptr ) {
1999     select_all();
2000   } else {
2001     if (find_info(_target) == nullptr) {
2002       _output->print_cr("Could not find target in BFS.");
2003       return;
2004     }
2005     if (_all_paths) {
2006       select_all_paths();
2007     } else {
2008       select_shortest_path();
2009     }
2010   }
2011 }
2012 
2013 // take all nodes from BFS
2014 void PrintBFS::select_all() {
2015   for (int i = 0; i < _worklist.length(); i++) {
2016     const Node* n = _worklist.at(i);
2017     Info* info = find_info(n);
2018     info->set_mark();
2019   }
2020 }
2021 
2022 // traverse backward from target, along edges found in BFS
2023 void PrintBFS::select_all_paths() {
2024   int pos = 0;
2025   GrowableArray<const Node*> backtrace;
2026   // start from target
2027   backtrace.push(_target);
2028   find_info(_target)->set_mark();
2029   // traverse backward
2030   while (pos < backtrace.length()) {
2031     const Node* n = backtrace.at(pos++);
2032     Info* info = find_info(n);
2033     for (int i = 0; i < info->edge_bwd.length(); i++) {
2034       // all backward edges
2035       const Node* back = info->edge_bwd.at(i);
2036       Info* back_info = find_info(back);
2037       if (!back_info->is_marked()) {
2038         // not yet found this on way back.
2039         back_info->set_distance_from_target(info->distance_from_target() + 1);
2040         if (back_info->distance_from_target() + back_info->distance() <= _max_distance) {
2041           // total distance is small enough
2042           back_info->set_mark();
2043           backtrace.push(back);
2044         }
2045       }
2046     }
2047   }
2048 }
2049 
2050 void PrintBFS::select_shortest_path() {
2051   const Node* current = _target;
2052   while (true) {
2053     Info* info = find_info(current);
2054     info->set_mark();
2055     if (current == _start) {
2056       break;
2057     }
2058     // first edge -> leads us one step closer to _start
2059     current = info->edge_bwd.at(0);
2060   }
2061 }
2062 
2063 // go through worklist in desired order, put the marked ones in print list
2064 void PrintBFS::sort() {
2065   if (_traverse_inputs && !_traverse_outputs) {
2066     // reverse order
2067     for (int i = _worklist.length() - 1; i >= 0; i--) {
2068       const Node* n = _worklist.at(i);
2069       Info* info = find_info(n);
2070       if (info->is_marked()) {
2071         _print_list.push(n);
2072       }
2073     }
2074   } else {
2075     // same order as worklist
2076     for (int i = 0; i < _worklist.length(); i++) {
2077       const Node* n = _worklist.at(i);
2078       Info* info = find_info(n);
2079       if (info->is_marked()) {
2080         _print_list.push(n);
2081       }
2082     }
2083   }
2084   if (_sort_idx) {
2085     _print_list.sort(node_idx_cmp);
2086   }
2087 }
2088 
2089 // go through printlist and print
2090 void PrintBFS::print() {
2091   if (_print_list.length() > 0 ) {
2092     print_header();
2093     for (int i = 0; i < _print_list.length(); i++) {
2094       const Node* n = _print_list.at(i);
2095       print_node(n);
2096     }
2097     if (_print_igv) {
2098       Compile* C = Compile::current();
2099       C->init_igv();
2100       C->igv_print_graph_to_network(nullptr, _print_list, _frame);
2101     }
2102   } else {
2103     _output->print_cr("No nodes to print.");
2104   }
2105 }
2106 
2107 void PrintBFS::print_options_help(bool print_examples) {
2108   _output->print_cr("Usage: node->dump_bfs(int max_distance, Node* target, char* options)");
2109   _output->print_cr("");
2110   _output->print_cr("Use cases:");
2111   _output->print_cr("  BFS traversal: no target required");
2112   _output->print_cr("  shortest path: set target");
2113   _output->print_cr("  all paths: set target and put 'A' in options");
2114   _output->print_cr("  detect loop: subcase of all paths, have start==target");
2115   _output->print_cr("");
2116   _output->print_cr("Arguments:");
2117   _output->print_cr("  this/start: staring point of BFS");
2118   _output->print_cr("  target:");
2119   _output->print_cr("    if null: simple BFS");
2120   _output->print_cr("    else: shortest path or all paths between this/start and target");
2121   _output->print_cr("  options:");
2122   _output->print_cr("    if null: same as \"cdmox@B\"");
2123   _output->print_cr("    else: use combination of following characters");
2124   _output->print_cr("      h: display this help info");
2125   _output->print_cr("      H: display this help info, with examples");
2126   _output->print_cr("      +: traverse in-edges (on if neither + nor -)");
2127   _output->print_cr("      -: traverse out-edges");
2128   _output->print_cr("      c: visit control nodes");
2129   _output->print_cr("      d: visit data nodes");
2130   _output->print_cr("      m: visit memory nodes");
2131   _output->print_cr("      o: visit other nodes");
2132   _output->print_cr("      x: visit mixed nodes");
2133   _output->print_cr("      C: boundary control nodes");
2134   _output->print_cr("      D: boundary data nodes");
2135   _output->print_cr("      M: boundary memory nodes");
2136   _output->print_cr("      O: boundary other nodes");
2137   _output->print_cr("      X: boundary mixed nodes");
2138   _output->print_cr("      #: display node category in color (not supported in all terminals)");
2139   _output->print_cr("      S: sort displayed nodes by node idx");
2140   _output->print_cr("      A: all paths (not just shortest path to target)");
2141   _output->print_cr("      @: print old nodes - before matching (if available)");
2142   _output->print_cr("      B: print scheduling blocks (if available)");
2143   _output->print_cr("      $: dump only, no header, no other columns");
2144   _output->print_cr("      !: show nodes on IGV (sent over network stream)");
2145   _output->print_cr("        (use preferably with dump_bfs(int, Node*, char*, void*, void*, void*)");
2146   _output->print_cr("         to produce a C2 stack trace along with the graph dump, see examples below)");
2147   _output->print_cr("");
2148   _output->print_cr("recursively follow edges to nodes with permitted visit types,");
2149   _output->print_cr("on the boundary additionally display nodes allowed in boundary types");
2150   _output->print_cr("Note: the categories can be overlapping. For example a mixed node");
2151   _output->print_cr("      can contain control and memory output. Some from the other");
2152   _output->print_cr("      category are also control (Halt, Return, etc).");
2153   _output->print_cr("");
2154   _output->print_cr("output columns:");
2155   _output->print_cr("  dist:  BFS distance to this/start");
2156   _output->print_cr("  apd:   all paths distance (d_outputart + d_target)");
2157   _output->print_cr("  block: block identifier, based on _pre_order");
2158   _output->print_cr("  head:  first node in block");
2159   _output->print_cr("  idom:  head node of idom block");
2160   _output->print_cr("  depth: depth of block (_dom_depth)");
2161   _output->print_cr("  old:   old IR node - before matching");
2162   _output->print_cr("  dump:  node->dump()");
2163   _output->print_cr("");
2164   _output->print_cr("Note: if none of the \"cmdxo\" characters are in the options string");
2165   _output->print_cr("      then we set all of them.");
2166   _output->print_cr("      This allows for short strings like \"#\" for colored input traversal");
2167   _output->print_cr("      or \"-#\" for colored output traversal.");
2168   if (print_examples) {
2169     _output->print_cr("");
2170     _output->print_cr("Examples:");
2171     _output->print_cr("  if->dump_bfs(10, 0, \"+cxo\")");
2172     _output->print_cr("    starting at some if node, traverse inputs recursively");
2173     _output->print_cr("    only along control (mixed and other can also be control)");
2174     _output->print_cr("  phi->dump_bfs(5, 0, \"-dxo\")");
2175     _output->print_cr("    starting at phi node, traverse outputs recursively");
2176     _output->print_cr("    only along data (mixed and other can also have data flow)");
2177     _output->print_cr("  find_node(385)->dump_bfs(3, 0, \"cdmox+#@B\")");
2178     _output->print_cr("    find inputs of node 385, up to 3 nodes up (+)");
2179     _output->print_cr("    traverse all nodes (cdmox), use colors (#)");
2180     _output->print_cr("    display old nodes and blocks, if they exist");
2181     _output->print_cr("    useful call to start with");
2182     _output->print_cr("  find_node(102)->dump_bfs(10, 0, \"dCDMOX-\")");
2183     _output->print_cr("    find non-data dependencies of a data node");
2184     _output->print_cr("    follow data node outputs until we find another category");
2185     _output->print_cr("    node as the boundary");
2186     _output->print_cr("  x->dump_bfs(10, y, 0)");
2187     _output->print_cr("    find shortest path from x to y, along any edge or node");
2188     _output->print_cr("    will not find a path if it is longer than 10");
2189     _output->print_cr("    useful to find how x and y are related");
2190     _output->print_cr("  find_node(741)->dump_bfs(20, find_node(746), \"c+\")");
2191     _output->print_cr("    find shortest control path between two nodes");
2192     _output->print_cr("  find_node(741)->dump_bfs(8, find_node(746), \"cdmox+A\")");
2193     _output->print_cr("    find all paths (A) between two nodes of length at most 8");
2194     _output->print_cr("  find_node(741)->dump_bfs(7, find_node(741), \"c+A\")");
2195     _output->print_cr("    find all control loops for this node");
2196     _output->print_cr("  find_node(741)->dump_bfs(7, find_node(741), \"c+A!\", $sp, $fp, $pc)");
2197     _output->print_cr("    same as above, but printing the resulting subgraph");
2198     _output->print_cr("    along with a C2 stack trace on IGV");
2199   }
2200 }
2201 
2202 bool PrintBFS::parse_options() {
2203   if (_options == nullptr) {
2204     _options = "cdmox@B"; // default options
2205   }
2206   size_t len = strlen(_options);
2207   for (size_t i = 0; i < len; i++) {
2208     switch (_options[i]) {
2209       case '+':
2210         _traverse_inputs = true;
2211         break;
2212       case '-':
2213         _traverse_outputs = true;
2214         break;
2215       case 'c':
2216         _filter_visit._control = true;
2217         break;
2218       case 'm':
2219         _filter_visit._memory = true;
2220         break;
2221       case 'd':
2222         _filter_visit._data = true;
2223         break;
2224       case 'x':
2225         _filter_visit._mixed = true;
2226         break;
2227       case 'o':
2228         _filter_visit._other = true;
2229         break;
2230       case 'C':
2231         _filter_boundary._control = true;
2232         break;
2233       case 'M':
2234         _filter_boundary._memory = true;
2235         break;
2236       case 'D':
2237         _filter_boundary._data = true;
2238         break;
2239       case 'X':
2240         _filter_boundary._mixed = true;
2241         break;
2242       case 'O':
2243         _filter_boundary._other = true;
2244         break;
2245       case 'S':
2246         _sort_idx = true;
2247         break;
2248       case 'A':
2249         _all_paths = true;
2250         break;
2251       case '#':
2252         _use_color = true;
2253         break;
2254       case 'B':
2255         _print_blocks = true;
2256         break;
2257       case '@':
2258         _print_old = true;
2259         break;
2260       case '$':
2261         _dump_only = true;
2262         break;
2263       case '!':
2264         _print_igv = true;
2265         break;
2266       case 'h':
2267         print_options_help(false);
2268         return false;
2269        case 'H':
2270         print_options_help(true);
2271         return false;
2272       default:
2273         _output->print_cr("dump_bfs: Unrecognized option \'%c\'", _options[i]);
2274         _output->print_cr("for help, run: find_node(0)->dump_bfs(0,0,\"H\")");
2275         return false;
2276     }
2277   }
2278   if (!_traverse_inputs && !_traverse_outputs) {
2279     _traverse_inputs = true;
2280   }
2281   if (_filter_visit.is_empty()) {
2282     _filter_visit.set_all();
2283   }
2284   Compile* C = Compile::current();
2285   _print_old &= (C->matcher() != nullptr); // only show old if there are new
2286   _print_blocks &= (C->cfg() != nullptr); // only show blocks if available
2287   return true;
2288 }
2289 
2290 void PrintBFS::DumpConfigColored::pre_dump(outputStream* st, const Node* n) {
2291   if (!_bfs->_use_color) {
2292     return;
2293   }
2294   Info* info = _bfs->find_info(n);
2295   if (info == nullptr || !info->is_marked()) {
2296     return;
2297   }
2298 
2299   const Type* t = n->bottom_type();
2300   switch (t->category()) {
2301     case Type::Category::Data:
2302       st->print("\u001b[34m");
2303       break;
2304     case Type::Category::Memory:
2305       st->print("\u001b[32m");
2306       break;
2307     case Type::Category::Mixed:
2308       st->print("\u001b[35m");
2309       break;
2310     case Type::Category::Control:
2311       st->print("\u001b[31m");
2312       break;
2313     case Type::Category::Other:
2314       st->print("\u001b[33m");
2315       break;
2316     case Type::Category::Undef:
2317       n->dump();
2318       assert(false, "category undef ??");
2319       break;
2320     default:
2321       n->dump();
2322       assert(false, "not covered");
2323       break;
2324   }
2325 }
2326 
2327 void PrintBFS::DumpConfigColored::post_dump(outputStream* st) {
2328   if (!_bfs->_use_color) {
2329     return;
2330   }
2331   st->print("\u001b[0m"); // white
2332 }
2333 
2334 Node* PrintBFS::old_node(const Node* n) {
2335   Compile* C = Compile::current();
2336   if (C->matcher() == nullptr || !C->node_arena()->contains(n)) {
2337     return (Node*)nullptr;
2338   } else {
2339     return C->matcher()->find_old_node(n);
2340   }
2341 }
2342 
2343 void PrintBFS::print_node_idx(const Node* n) {
2344   Compile* C = Compile::current();
2345   char buf[30];
2346   if (n == nullptr) {
2347     os::snprintf_checked(buf, sizeof(buf), "_");           // null
2348   } else if (C->node_arena()->contains(n)) {
2349     os::snprintf_checked(buf, sizeof(buf), "%d", n->_idx);  // new node
2350   } else {
2351     os::snprintf_checked(buf, sizeof(buf), "o%d", n->_idx); // old node
2352   }
2353   _output->print("%6s", buf);
2354 }
2355 
2356 void PrintBFS::print_block_id(const Block* b) {
2357   Compile* C = Compile::current();
2358   char buf[30];
2359   os::snprintf_checked(buf, sizeof(buf), "B%d", b->_pre_order);
2360   _output->print("%7s", buf);
2361 }
2362 
2363 void PrintBFS::print_node_block(const Node* n) {
2364   Compile* C = Compile::current();
2365   Block* b = C->node_arena()->contains(n)
2366              ? C->cfg()->get_block_for_node(n)
2367              : nullptr; // guard against old nodes
2368   if (b == nullptr) {
2369     _output->print("      _"); // Block
2370     _output->print("     _");  // head
2371     _output->print("     _");  // idom
2372     _output->print("      _"); // depth
2373   } else {
2374     print_block_id(b);
2375     print_node_idx(b->head());
2376     if (b->_idom) {
2377       print_node_idx(b->_idom->head());
2378     } else {
2379       _output->print("     _"); // idom
2380     }
2381     _output->print("%6d ", b->_dom_depth);
2382   }
2383 }
2384 
2385 // filter, and add to worklist, add info, note traversal edges
2386 void PrintBFS::maybe_traverse(const Node* src, const Node* dst) {
2387   if (dst != nullptr &&
2388      (_filter_visit.accepts(dst) ||
2389       _filter_boundary.accepts(dst) ||
2390       dst == _start)) { // correct category or start?
2391     if (find_info(dst) == nullptr) {
2392       // never visited - set up info
2393       _worklist.push(dst);
2394       int d = 0;
2395       if (dst != _start) {
2396         d = find_info(src)->distance() + 1;
2397       }
2398       make_info(dst, d);
2399     }
2400     if (src != dst) {
2401       // traversal edges useful during select
2402       find_info(dst)->edge_bwd.push(src);
2403     }
2404   }
2405 }
2406 
2407 void PrintBFS::print_header() const {
2408   if (_dump_only) {
2409     return; // no header in dump only mode
2410   }
2411   _output->print("dist");                         // distance
2412   if (_all_paths) {
2413     _output->print(" apd");                       // all paths distance
2414   }
2415   if (_print_blocks) {
2416     _output->print(" [block  head  idom depth]"); // block
2417   }
2418   if (_print_old) {
2419     _output->print("   old");                     // old node
2420   }
2421   _output->print(" dump\n");                      // node dump
2422   _output->print_cr("---------------------------------------------");
2423 }
2424 
2425 void PrintBFS::print_node(const Node* n) {
2426   if (_dump_only) {
2427     n->dump("\n", false, _output, &_dcc);
2428     return;
2429   }
2430   _output->print("%4d", find_info(n)->distance());// distance
2431   if (_all_paths) {
2432     Info* info = find_info(n);
2433     int apd = info->distance() + info->distance_from_target();
2434     _output->print("%4d", apd);                   // all paths distance
2435   }
2436   if (_print_blocks) {
2437     print_node_block(n);                          // block
2438   }
2439   if (_print_old) {
2440     print_node_idx(old_node(n));                  // old node
2441   }
2442   _output->print(" ");
2443   n->dump("\n", false, _output, &_dcc);           // node dump
2444 }
2445 
2446 //------------------------------dump_bfs--------------------------------------
2447 // Call this from debugger
2448 // Useful for BFS traversal, shortest path, all path, loop detection, etc
2449 // Designed to be more readable, and provide additional info
2450 // To find all options, run:
2451 //   find_node(0)->dump_bfs(0,0,"H")
2452 void Node::dump_bfs(const int max_distance, Node* target, const char* options) const {
2453   dump_bfs(max_distance, target, options, tty);
2454 }
2455 
2456 // Used to dump to stream.
2457 void Node::dump_bfs(const int max_distance, Node* target, const char* options, outputStream* st, const frame* fr) const {
2458   PrintBFS bfs(this, max_distance, target, options, st, fr);
2459   bfs.run();
2460 }
2461 
2462 // Call this from debugger, with default arguments
2463 void Node::dump_bfs(const int max_distance) const {
2464   dump_bfs(max_distance, nullptr, nullptr);
2465 }
2466 
2467 // Call this from debugger, with stack handling register arguments for IGV dumps.
2468 // Example: p find_node(741)->dump_bfs(7, find_node(741), "c+A!", $sp, $fp, $pc).
2469 void Node::dump_bfs(const int max_distance, Node* target, const char* options, void* sp, void* fp, void* pc) const {
2470   frame fr(sp, fp, pc);
2471   dump_bfs(max_distance, target, options, tty, &fr);
2472 }
2473 
2474 // -----------------------------dump_idx---------------------------------------
2475 void Node::dump_idx(bool align, outputStream* st, DumpConfig* dc) const {
2476   if (dc != nullptr) {
2477     dc->pre_dump(st, this);
2478   }
2479   Compile* C = Compile::current();
2480   bool is_new = C->node_arena()->contains(this);
2481   if (align) { // print prefix empty spaces$
2482     // +1 for leading digit, +1 for "o"
2483     uint max_width = (C->unique() == 0 ? 0 : static_cast<uint>(log10(static_cast<double>(C->unique())))) + 2;
2484     // +1 for leading digit, maybe +1 for "o"
2485     uint width = (_idx == 0 ? 0 : static_cast<uint>(log10(static_cast<double>(_idx)))) + 1 + (is_new ? 0 : 1);
2486     while (max_width > width) {
2487       st->print(" ");
2488       width++;
2489     }
2490   }
2491   if (!is_new) {
2492     st->print("o");
2493   }
2494   st->print("%d", _idx);
2495   if (dc != nullptr) {
2496     dc->post_dump(st);
2497   }
2498 }
2499 
2500 // -----------------------------dump_name--------------------------------------
2501 void Node::dump_name(outputStream* st, DumpConfig* dc) const {
2502   if (dc != nullptr) {
2503     dc->pre_dump(st, this);
2504   }
2505   st->print("%s", Name());
2506   if (dc != nullptr) {
2507     dc->post_dump(st);
2508   }
2509 }
2510 
2511 // -----------------------------Name-------------------------------------------
2512 extern const char *NodeClassNames[];
2513 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
2514 
2515 static bool is_disconnected(const Node* n) {
2516   for (uint i = 0; i < n->req(); i++) {
2517     if (n->in(i) != nullptr)  return false;
2518   }
2519   return true;
2520 }
2521 
2522 #ifdef ASSERT
2523 void Node::dump_orig(outputStream *st, bool print_key) const {
2524   Compile* C = Compile::current();
2525   Node* orig = _debug_orig;
2526   if (not_a_node(orig)) orig = nullptr;
2527   if (orig != nullptr && !C->node_arena()->contains(orig)) orig = nullptr;
2528   if (orig == nullptr) return;
2529   if (print_key) {
2530     st->print(" !orig=");
2531   }
2532   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
2533   if (not_a_node(fast)) fast = nullptr;
2534   while (orig != nullptr) {
2535     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
2536     if (discon) st->print("[");
2537     if (!Compile::current()->node_arena()->contains(orig))
2538       st->print("o");
2539     st->print("%d", orig->_idx);
2540     if (discon) st->print("]");
2541     orig = orig->debug_orig();
2542     if (not_a_node(orig)) orig = nullptr;
2543     if (orig != nullptr && !C->node_arena()->contains(orig)) orig = nullptr;
2544     if (orig != nullptr) st->print(",");
2545     if (fast != nullptr) {
2546       // Step fast twice for each single step of orig:
2547       fast = fast->debug_orig();
2548       if (not_a_node(fast)) fast = nullptr;
2549       if (fast != nullptr && fast != orig) {
2550         fast = fast->debug_orig();
2551         if (not_a_node(fast)) fast = nullptr;
2552       }
2553       if (fast == orig) {
2554         st->print("...");
2555         break;
2556       }
2557     }
2558   }
2559 }
2560 
2561 void Node::set_debug_orig(Node* orig) {
2562   _debug_orig = orig;
2563   if (BreakAtNode == 0)  return;
2564   if (not_a_node(orig))  orig = nullptr;
2565   int trip = 10;
2566   while (orig != nullptr) {
2567     if (orig->debug_idx() == BreakAtNode || (uintx)orig->_idx == BreakAtNode) {
2568       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=" UINT64_FORMAT " orig._idx=%d orig._debug_idx=" UINT64_FORMAT,
2569                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
2570       BREAKPOINT;
2571     }
2572     orig = orig->debug_orig();
2573     if (not_a_node(orig))  orig = nullptr;
2574     if (trip-- <= 0)  break;
2575   }
2576 }
2577 #endif //ASSERT
2578 
2579 //------------------------------dump------------------------------------------
2580 // Dump a Node
2581 void Node::dump(const char* suffix, bool mark, outputStream* st, DumpConfig* dc) const {
2582   Compile* C = Compile::current();
2583   bool is_new = C->node_arena()->contains(this);
2584   C->_in_dump_cnt++;
2585 
2586   // idx mark name ===
2587   dump_idx(true, st, dc);
2588   st->print(mark ? " >" : "  ");
2589   dump_name(st, dc);
2590   st->print("  === ");
2591 
2592   // Dump the required and precedence inputs
2593   dump_req(st, dc);
2594   dump_prec(st, dc);
2595   // Dump the outputs
2596   dump_out(st, dc);
2597 
2598   if (is_disconnected(this)) {
2599 #ifdef ASSERT
2600     st->print("  [" UINT64_FORMAT "]", debug_idx());
2601     dump_orig(st);
2602 #endif
2603     st->cr();
2604     C->_in_dump_cnt--;
2605     return;                     // don't process dead nodes
2606   }
2607 
2608   if (C->clone_map().value(_idx) != 0) {
2609     C->clone_map().dump(_idx, st);
2610   }
2611   // Dump node-specific info
2612   dump_spec(st);
2613 #ifdef ASSERT
2614   // Dump the non-reset _debug_idx
2615   if (Verbose && WizardMode) {
2616     st->print("  [" UINT64_FORMAT "]", debug_idx());
2617   }
2618 #endif
2619 
2620   const Type *t = bottom_type();
2621 
2622   if (t != nullptr && (t->isa_instptr() || t->isa_instklassptr())) {
2623     const TypeInstPtr  *toop = t->isa_instptr();
2624     const TypeInstKlassPtr *tkls = t->isa_instklassptr();
2625     if (toop) {
2626       st->print("  Oop:");
2627     } else if (tkls) {
2628       st->print("  Klass:");
2629     }
2630     t->dump_on(st);
2631   } else if (t == Type::MEMORY) {
2632     st->print("  Memory:");
2633     MemNode::dump_adr_type(adr_type(), st);
2634   } else if (Verbose || WizardMode) {
2635     st->print("  Type:");
2636     if (t) {
2637       t->dump_on(st);
2638     } else {
2639       st->print("no type");
2640     }
2641   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
2642     // Dump MachSpillcopy vector type.
2643     t->dump_on(st);
2644   }
2645   if (is_new) {
2646     DEBUG_ONLY(dump_orig(st));
2647     Node_Notes* nn = C->node_notes_at(_idx);
2648     if (nn != nullptr && !nn->is_clear()) {
2649       if (nn->jvms() != nullptr) {
2650         st->print(" !jvms:");
2651         nn->jvms()->dump_spec(st);
2652       }
2653     }
2654   }
2655   if (suffix) st->print("%s", suffix);
2656   C->_in_dump_cnt--;
2657 }
2658 
2659 // call from debugger: dump node to tty with newline
2660 void Node::dump() const {
2661   dump("\n");
2662 }
2663 
2664 //------------------------------dump_req--------------------------------------
2665 void Node::dump_req(outputStream* st, DumpConfig* dc) const {
2666   // Dump the required input edges
2667   for (uint i = 0; i < req(); i++) {    // For all required inputs
2668     Node* d = in(i);
2669     if (d == nullptr) {
2670       st->print("_ ");
2671     } else if (not_a_node(d)) {
2672       st->print("not_a_node ");  // uninitialized, sentinel, garbage, etc.
2673     } else {
2674       d->dump_idx(false, st, dc);
2675       st->print(" ");
2676     }
2677   }
2678 }
2679 
2680 
2681 //------------------------------dump_prec-------------------------------------
2682 void Node::dump_prec(outputStream* st, DumpConfig* dc) const {
2683   // Dump the precedence edges
2684   int any_prec = 0;
2685   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
2686     Node* p = in(i);
2687     if (p != nullptr) {
2688       if (!any_prec++) st->print(" |");
2689       if (not_a_node(p)) { st->print("not_a_node "); continue; }
2690       p->dump_idx(false, st, dc);
2691       st->print(" ");
2692     }
2693   }
2694 }
2695 
2696 //------------------------------dump_out--------------------------------------
2697 void Node::dump_out(outputStream* st, DumpConfig* dc) const {
2698   // Delimit the output edges
2699   st->print(" [[ ");
2700   // Dump the output edges
2701   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
2702     Node* u = _out[i];
2703     if (u == nullptr) {
2704       st->print("_ ");
2705     } else if (not_a_node(u)) {
2706       st->print("not_a_node ");
2707     } else {
2708       u->dump_idx(false, st, dc);
2709       st->print(" ");
2710     }
2711   }
2712   st->print("]] ");
2713 }
2714 
2715 //------------------------------dump-------------------------------------------
2716 // call from debugger: dump Node's inputs (or outputs if d negative)
2717 void Node::dump(int d) const {
2718   dump_bfs(abs(d), nullptr, (d > 0) ? "+$" : "-$");
2719 }
2720 
2721 //------------------------------dump_ctrl--------------------------------------
2722 // call from debugger: dump Node's control inputs (or outputs if d negative)
2723 void Node::dump_ctrl(int d) const {
2724   dump_bfs(abs(d), nullptr, (d > 0) ? "+$c" : "-$c");
2725 }
2726 
2727 //-----------------------------dump_compact------------------------------------
2728 void Node::dump_comp() const {
2729   this->dump_comp("\n");
2730 }
2731 
2732 //-----------------------------dump_compact------------------------------------
2733 // Dump a Node in compact representation, i.e., just print its name and index.
2734 // Nodes can specify additional specifics to print in compact representation by
2735 // implementing dump_compact_spec.
2736 void Node::dump_comp(const char* suffix, outputStream *st) const {
2737   Compile* C = Compile::current();
2738   C->_in_dump_cnt++;
2739   st->print("%s(%d)", Name(), _idx);
2740   this->dump_compact_spec(st);
2741   if (suffix) {
2742     st->print("%s", suffix);
2743   }
2744   C->_in_dump_cnt--;
2745 }
2746 
2747 // VERIFICATION CODE
2748 // Verify all nodes if verify_depth is negative
2749 void Node::verify(int verify_depth, VectorSet& visited, Node_List& worklist) {
2750   assert(verify_depth != 0, "depth should not be 0");
2751   Compile* C = Compile::current();
2752   uint last_index_on_current_depth = worklist.size() - 1;
2753   verify_depth--; // Visiting the first node on depth 1
2754   // Only add nodes to worklist if verify_depth is negative (visit all nodes) or greater than 0
2755   bool add_to_worklist = verify_depth != 0;
2756 
2757   for (uint list_index = 0; list_index < worklist.size(); list_index++) {
2758     Node* n = worklist[list_index];
2759 
2760     if (n->is_Con() && n->bottom_type() == Type::TOP) {
2761       if (C->cached_top_node() == nullptr) {
2762         C->set_cached_top_node((Node*)n);
2763       }
2764       assert(C->cached_top_node() == n, "TOP node must be unique");
2765     }
2766 
2767     uint in_len = n->len();
2768     for (uint i = 0; i < in_len; i++) {
2769       Node* x = n->_in[i];
2770       if (!x || x->is_top()) {
2771         continue;
2772       }
2773 
2774       // Verify my input has a def-use edge to me
2775       // Count use-def edges from n to x
2776       int cnt = 1;
2777       for (uint j = 0; j < i; j++) {
2778         if (n->_in[j] == x) {
2779           cnt++;
2780           break;
2781         }
2782       }
2783       if (cnt == 2) {
2784         // x is already checked as n's previous input, skip its duplicated def-use count checking
2785         continue;
2786       }
2787       for (uint j = i + 1; j < in_len; j++) {
2788         if (n->_in[j] == x) {
2789           cnt++;
2790         }
2791       }
2792 
2793       // Count def-use edges from x to n
2794       uint max = x->_outcnt;
2795       for (uint k = 0; k < max; k++) {
2796         if (x->_out[k] == n) {
2797           cnt--;
2798         }
2799       }
2800       assert(cnt == 0, "mismatched def-use edge counts");
2801 
2802       if (add_to_worklist && !visited.test_set(x->_idx)) {
2803         worklist.push(x);
2804       }
2805     }
2806 
2807     if (verify_depth > 0 && list_index == last_index_on_current_depth) {
2808       // All nodes on this depth were processed and its inputs are on the worklist. Decrement verify_depth and
2809       // store the current last list index which is the last node in the list with the new depth. All nodes
2810       // added afterwards will have a new depth again. Stop adding new nodes if depth limit is reached (=0).
2811       verify_depth--;
2812       if (verify_depth == 0) {
2813         add_to_worklist = false;
2814       }
2815       last_index_on_current_depth = worklist.size() - 1;
2816     }
2817   }
2818 }
2819 #endif // not PRODUCT
2820 
2821 //------------------------------Registers--------------------------------------
2822 // Do we Match on this edge index or not?  Generally false for Control
2823 // and true for everything else.  Weird for calls & returns.
2824 uint Node::match_edge(uint idx) const {
2825   return idx;                   // True for other than index 0 (control)
2826 }
2827 
2828 // Register classes are defined for specific machines
2829 const RegMask &Node::out_RegMask() const {
2830   ShouldNotCallThis();
2831   return RegMask::EMPTY;
2832 }
2833 
2834 const RegMask &Node::in_RegMask(uint) const {
2835   ShouldNotCallThis();
2836   return RegMask::EMPTY;
2837 }
2838 
2839 void Node_Array::grow(uint i) {
2840   assert(i >= _max, "Should have been checked before, use maybe_grow?");
2841   assert(_max > 0, "invariant");
2842   uint old = _max;
2843   _max = next_power_of_2(i);
2844   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2845   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2846 }
2847 
2848 void Node_Array::insert(uint i, Node* n) {
2849   if (_nodes[_max - 1]) {
2850     grow(_max);
2851   }
2852   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i + 1], ((_max - i - 1) * sizeof(Node*)));
2853   _nodes[i] = n;
2854 }
2855 
2856 void Node_Array::remove(uint i) {
2857   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i + 1], (HeapWord*)&_nodes[i], ((_max - i - 1) * sizeof(Node*)));
2858   _nodes[_max - 1] = nullptr;
2859 }
2860 
2861 void Node_Array::dump() const {
2862 #ifndef PRODUCT
2863   for (uint i = 0; i < _max; i++) {
2864     Node* nn = _nodes[i];
2865     if (nn != nullptr) {
2866       tty->print("%5d--> ",i); nn->dump();
2867     }
2868   }
2869 #endif
2870 }
2871 
2872 //--------------------------is_iteratively_computed------------------------------
2873 // Operation appears to be iteratively computed (such as an induction variable)
2874 // It is possible for this operation to return false for a loop-varying
2875 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2876 bool Node::is_iteratively_computed() {
2877   if (ideal_reg()) { // does operation have a result register?
2878     for (uint i = 1; i < req(); i++) {
2879       Node* n = in(i);
2880       if (n != nullptr && n->is_Phi()) {
2881         for (uint j = 1; j < n->req(); j++) {
2882           if (n->in(j) == this) {
2883             return true;
2884           }
2885         }
2886       }
2887     }
2888   }
2889   return false;
2890 }
2891 
2892 //--------------------------find_similar------------------------------
2893 // Return a node with opcode "opc" and same inputs as "this" if one can
2894 // be found; Otherwise return null;
2895 Node* Node::find_similar(int opc) {
2896   if (req() >= 2) {
2897     Node* def = in(1);
2898     if (def && def->outcnt() >= 2) {
2899       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2900         Node* use = def->fast_out(i);
2901         if (use != this &&
2902             use->Opcode() == opc &&
2903             use->req() == req() &&
2904             has_same_inputs_as(use)) {
2905           return use;
2906         }
2907       }
2908     }
2909   }
2910   return nullptr;
2911 }
2912 
2913 bool Node::has_same_inputs_as(const Node* other) const {
2914   assert(req() == other->req(), "should have same number of inputs");
2915   for (uint j = 0; j < other->req(); j++) {
2916     if (in(j) != other->in(j)) {
2917       return false;
2918     }
2919   }
2920   return true;
2921 }
2922 
2923 Node* Node::unique_multiple_edges_out_or_null() const {
2924   Node* use = nullptr;
2925   for (DUIterator_Fast kmax, k = fast_outs(kmax); k < kmax; k++) {
2926     Node* u = fast_out(k);
2927     if (use == nullptr) {
2928       use = u; // first use
2929     } else if (u != use) {
2930       return nullptr; // not unique
2931     } else {
2932       // secondary use
2933     }
2934   }
2935   return use;
2936 }
2937 
2938 //--------------------------unique_ctrl_out_or_null-------------------------
2939 // Return the unique control out if only one. Null if none or more than one.
2940 Node* Node::unique_ctrl_out_or_null() const {
2941   Node* found = nullptr;
2942   for (uint i = 0; i < outcnt(); i++) {
2943     Node* use = raw_out(i);
2944     if (use->is_CFG() && use != this) {
2945       if (found != nullptr) {
2946         return nullptr;
2947       }
2948       found = use;
2949     }
2950   }
2951   return found;
2952 }
2953 
2954 //--------------------------unique_ctrl_out------------------------------
2955 // Return the unique control out. Asserts if none or more than one control out.
2956 Node* Node::unique_ctrl_out() const {
2957   Node* ctrl = unique_ctrl_out_or_null();
2958   assert(ctrl != nullptr, "control out is assumed to be unique");
2959   return ctrl;
2960 }
2961 
2962 void Node::ensure_control_or_add_prec(Node* c) {
2963   if (in(0) == nullptr) {
2964     set_req(0, c);
2965   } else if (in(0) != c) {
2966     add_prec(c);
2967   }
2968 }
2969 
2970 void Node::add_prec_from(Node* n) {
2971   for (uint i = n->req(); i < n->len(); i++) {
2972     Node* prec = n->in(i);
2973     if (prec != nullptr) {
2974       add_prec(prec);
2975     }
2976   }
2977 }
2978 
2979 bool Node::is_dead_loop_safe() const {
2980   if (is_Phi()) {
2981     return true;
2982   }
2983   if (is_Proj() && in(0) == nullptr)  {
2984     return true;
2985   }
2986   if ((_flags & (Flag_is_dead_loop_safe | Flag_is_Con)) != 0) {
2987     if (!is_Proj()) {
2988       return true;
2989     }
2990     if (in(0)->is_Allocate()) {
2991       return false;
2992     }
2993     // MemNode::can_see_stored_value() peeks through the boxing call
2994     if (in(0)->is_CallStaticJava() && in(0)->as_CallStaticJava()->is_boxing_method()) {
2995       return false;
2996     }
2997     return true;
2998   }
2999   return false;
3000 }
3001 
3002 bool Node::is_div_or_mod(BasicType bt) const { return Opcode() == Op_Div(bt) || Opcode() == Op_Mod(bt) ||
3003                                                       Opcode() == Op_UDiv(bt) || Opcode() == Op_UMod(bt); }
3004 
3005 // `maybe_pure_function` is assumed to be the input of `this`. This is a bit redundant,
3006 // but we already have and need maybe_pure_function in all the call sites, so
3007 // it makes it obvious that the `maybe_pure_function` is the same node as in the caller,
3008 // while it takes more thinking to realize that a locally computed in(0) must be equal to
3009 // the local in the caller.
3010 bool Node::is_data_proj_of_pure_function(const Node* maybe_pure_function) const {
3011   return Opcode() == Op_Proj && as_Proj()->_con == TypeFunc::Parms && maybe_pure_function->is_CallLeafPure();
3012 }
3013 
3014 //--------------------------has_non_debug_uses------------------------------
3015 // Checks whether the node has any non-debug uses or not.
3016 bool Node::has_non_debug_uses() const {
3017   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
3018     Node* u = fast_out(i);
3019     if (u->is_SafePoint()) {
3020       if (u->is_Call() && u->as_Call()->has_non_debug_use(this)) {
3021         return true;
3022       }
3023       // Non-call safepoints have only debug uses.
3024     } else if (u->is_ReachabilityFence()) {
3025       // Reachability fence is treated as debug use.
3026     } else {
3027       return true; // everything else is conservatively treated as non-debug use
3028     }
3029   }
3030   return false; // no non-debug uses found
3031 }
3032 
3033 //=============================================================================
3034 //------------------------------yank-------------------------------------------
3035 // Find and remove
3036 void Node_List::yank( Node *n ) {
3037   uint i;
3038   for (i = 0; i < _cnt; i++) {
3039     if (_nodes[i] == n) {
3040       break;
3041     }
3042   }
3043 
3044   if (i < _cnt) {
3045     _nodes[i] = _nodes[--_cnt];
3046   }
3047 }
3048 
3049 //------------------------------dump-------------------------------------------
3050 void Node_List::dump() const {
3051 #ifndef PRODUCT
3052   for (uint i = 0; i < _cnt; i++) {
3053     if (_nodes[i]) {
3054       tty->print("%5d--> ", i);
3055       _nodes[i]->dump();
3056     }
3057   }
3058 #endif
3059 }
3060 
3061 void Node_List::dump_simple() const {
3062 #ifndef PRODUCT
3063   for (uint i = 0; i < _cnt; i++) {
3064     if( _nodes[i] ) {
3065       tty->print(" %d", _nodes[i]->_idx);
3066     } else {
3067       tty->print(" null");
3068     }
3069   }
3070 #endif
3071 }
3072 
3073 //=============================================================================
3074 //------------------------------remove-----------------------------------------
3075 void Unique_Node_List::remove(Node* n) {
3076   if (_in_worklist.test(n->_idx)) {
3077     for (uint i = 0; i < size(); i++) {
3078       if (_nodes[i] == n) {
3079         map(i, Node_List::pop());
3080         _in_worklist.remove(n->_idx);
3081         return;
3082       }
3083     }
3084     ShouldNotReachHere();
3085   }
3086 }
3087 
3088 //-----------------------remove_useless_nodes----------------------------------
3089 // Remove useless nodes from worklist
3090 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
3091   for (uint i = 0; i < size(); ++i) {
3092     Node *n = at(i);
3093     assert( n != nullptr, "Did not expect null entries in worklist");
3094     if (!useful.test(n->_idx)) {
3095       _in_worklist.remove(n->_idx);
3096       map(i, Node_List::pop());
3097       --i;  // Visit popped node
3098       // If it was last entry, loop terminates since size() was also reduced
3099     }
3100   }
3101 }
3102 
3103 //=============================================================================
3104 void Node_Stack::grow() {
3105   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
3106   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
3107   size_t max = old_max << 1;             // max * 2
3108   _inodes = REALLOC_ARENA_ARRAY(_a, _inodes, old_max, max);
3109   _inode_max = _inodes + max;
3110   _inode_top = _inodes + old_top;        // restore _top
3111 }
3112 
3113 // Node_Stack is used to map nodes.
3114 Node* Node_Stack::find(uint idx) const {
3115   uint sz = size();
3116   for (uint i = 0; i < sz; i++) {
3117     if (idx == index_at(i)) {
3118       return node_at(i);
3119     }
3120   }
3121   return nullptr;
3122 }
3123 
3124 //=============================================================================
3125 uint TypeNode::size_of() const { return sizeof(*this); }
3126 #ifndef PRODUCT
3127 void TypeNode::dump_spec(outputStream *st) const {
3128   if (!Verbose && !WizardMode) {
3129     // standard dump does this in Verbose and WizardMode
3130     st->print(" #"); _type->dump_on(st);
3131   }
3132 }
3133 
3134 void TypeNode::dump_compact_spec(outputStream *st) const {
3135   st->print("#");
3136   _type->dump_on(st);
3137 }
3138 #endif
3139 uint TypeNode::hash() const {
3140   return Node::hash() + _type->hash();
3141 }
3142 bool TypeNode::cmp(const Node& n) const {
3143   return Type::equals(_type, n.as_Type()->_type);
3144 }
3145 const Type* TypeNode::bottom_type() const { return _type; }
3146 const Type* TypeNode::Value(PhaseGVN* phase) const { return _type; }
3147 
3148 //------------------------------ideal_reg--------------------------------------
3149 uint TypeNode::ideal_reg() const {
3150   return _type->ideal_reg();
3151 }
3152 
3153 void TypeNode::make_path_dead(PhaseIterGVN* igvn, PhaseIdealLoop* loop, Node* ctrl_use, uint j, const char* phase_str) {
3154   Node* c = ctrl_use->in(j);
3155   if (igvn->type(c) != Type::TOP) {
3156     igvn->replace_input_of(ctrl_use, j, igvn->C->top());
3157     create_halt_path(igvn, c, loop, phase_str);
3158   }
3159 }
3160 
3161 // This Type node is dead. It could be because the type that it captures and the type of the node computed from its
3162 // inputs do not intersect anymore. That node has some uses along some control flow paths. Those control flow paths must
3163 // be unreachable as using a dead value makes no sense. For the Type node to capture a narrowed down type, some control
3164 // flow construct must guard the Type node (an If node usually). When the Type node becomes dead, the guard usually
3165 // constant folds and the control flow that leads to the Type node becomes unreachable. There are cases where that
3166 // doesn't happen, however. They are handled here by following uses of the Type node until a CFG or a Phi to find dead
3167 // paths. The dead paths are then replaced by a Halt node.
3168 void TypeNode::make_paths_from_here_dead(PhaseIterGVN* igvn, PhaseIdealLoop* loop, const char* phase_str) {
3169   Unique_Node_List wq;
3170   wq.push(this);
3171   for (uint i = 0; i < wq.size(); ++i) {
3172     Node* n = wq.at(i);
3173     for (DUIterator_Fast kmax, k = n->fast_outs(kmax); k < kmax; k++) {
3174       Node* u = n->fast_out(k);
3175       if (u->is_CFG()) {
3176         assert(!u->is_Region(), "Can't reach a Region without going through a Phi");
3177         make_path_dead(igvn, loop, u, 0, phase_str);
3178       } else if (u->is_Phi()) {
3179         Node* r = u->in(0);
3180         assert(r->is_Region() || r->is_top(), "unexpected Phi's control");
3181         if (r->is_Region()) {
3182           for (uint j = 1; j < u->req(); ++j) {
3183             if (u->in(j) == n && r->in(j) != nullptr) {
3184               make_path_dead(igvn, loop, r, j, phase_str);
3185             }
3186           }
3187         }
3188       } else {
3189         wq.push(u);
3190       }
3191     }
3192   }
3193 }
3194 
3195 void TypeNode::create_halt_path(PhaseIterGVN* igvn, Node* c, PhaseIdealLoop* loop, const char* phase_str) const {
3196   Node* frame = new ParmNode(igvn->C->start(), TypeFunc::FramePtr);
3197   if (loop == nullptr) {
3198     igvn->register_new_node_with_optimizer(frame);
3199   } else {
3200     loop->register_new_node(frame, igvn->C->start());
3201   }
3202 
3203   stringStream ss;
3204   ss.print("dead path discovered by TypeNode during %s", phase_str);
3205 
3206   Node* halt = new HaltNode(c, frame, ss.as_string(igvn->C->comp_arena()));
3207   if (loop == nullptr) {
3208     igvn->register_new_node_with_optimizer(halt);
3209   } else {
3210     loop->register_control(halt, loop->ltree_root(), c);
3211   }
3212   igvn->add_input_to(igvn->C->root(), halt);
3213 }
3214 
3215 Node* TypeNode::Ideal(PhaseGVN* phase, bool can_reshape) {
3216   if (KillPathsReachableByDeadTypeNode && can_reshape && Value(phase) == Type::TOP) {
3217     PhaseIterGVN* igvn = phase->is_IterGVN();
3218     Node* top = igvn->C->top();
3219     ResourceMark rm;
3220     make_paths_from_here_dead(igvn, nullptr, "igvn");
3221     return top;
3222   }
3223 
3224   return Node::Ideal(phase, can_reshape);
3225 }
--- EOF ---