1 /*
   2  * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/barrierSet.hpp"
  27 #include "gc/shared/c2/barrierSetC2.hpp"
  28 #include "libadt/vectset.hpp"
  29 #include "memory/allocation.inline.hpp"
  30 #include "memory/resourceArea.hpp"
  31 #include "opto/ad.hpp"
  32 #include "opto/callGenerator.hpp"
  33 #include "opto/castnode.hpp"
  34 #include "opto/cfgnode.hpp"
  35 #include "opto/connode.hpp"
  36 #include "opto/inlinetypenode.hpp"
  37 #include "opto/loopnode.hpp"
  38 #include "opto/machnode.hpp"
  39 #include "opto/matcher.hpp"
  40 #include "opto/node.hpp"
  41 #include "opto/opcodes.hpp"
  42 #include "opto/regmask.hpp"
  43 #include "opto/rootnode.hpp"
  44 #include "opto/type.hpp"
  45 #include "utilities/copy.hpp"
  46 #include "utilities/macros.hpp"
  47 #include "utilities/powerOfTwo.hpp"
  48 #include "utilities/stringUtils.hpp"
  49 
  50 class RegMask;
  51 // #include "phase.hpp"
  52 class PhaseTransform;
  53 class PhaseGVN;
  54 
  55 // Arena we are currently building Nodes in
  56 const uint Node::NotAMachineReg = 0xffff0000;
  57 
  58 #ifndef PRODUCT
  59 extern uint nodes_created;
  60 #endif
  61 #ifdef __clang__
  62 #pragma clang diagnostic push
  63 #pragma GCC diagnostic ignored "-Wuninitialized"
  64 #endif
  65 
  66 #ifdef ASSERT
  67 
  68 //-------------------------- construct_node------------------------------------
  69 // Set a breakpoint here to identify where a particular node index is built.
  70 void Node::verify_construction() {
  71   _debug_orig = nullptr;
  72   // The decimal digits of _debug_idx are <compile_id> followed by 10 digits of <_idx>
  73   Compile* C = Compile::current();
  74   assert(C->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  75   uint64_t new_debug_idx = (uint64_t)C->compile_id() * 10000000000 + _idx;
  76   set_debug_idx(new_debug_idx);
  77   if (!C->phase_optimize_finished()) {
  78     // Only check assert during parsing and optimization phase. Skip it while generating code.
  79     assert(C->live_nodes() <= C->max_node_limit(), "Live Node limit exceeded limit");
  80   }
  81   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (uint64_t)_idx == BreakAtNode)) {
  82     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=" UINT64_FORMAT, _idx, _debug_idx);
  83     BREAKPOINT;
  84   }
  85 #if OPTO_DU_ITERATOR_ASSERT
  86   _last_del = nullptr;
  87   _del_tick = 0;
  88 #endif
  89   _hash_lock = 0;
  90 }
  91 
  92 
  93 // #ifdef ASSERT ...
  94 
  95 #if OPTO_DU_ITERATOR_ASSERT
  96 void DUIterator_Common::sample(const Node* node) {
  97   _vdui     = VerifyDUIterators;
  98   _node     = node;
  99   _outcnt   = node->_outcnt;
 100   _del_tick = node->_del_tick;
 101   _last     = nullptr;
 102 }
 103 
 104 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
 105   assert(_node     == node, "consistent iterator source");
 106   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
 107 }
 108 
 109 void DUIterator_Common::verify_resync() {
 110   // Ensure that the loop body has just deleted the last guy produced.
 111   const Node* node = _node;
 112   // Ensure that at least one copy of the last-seen edge was deleted.
 113   // Note:  It is OK to delete multiple copies of the last-seen edge.
 114   // Unfortunately, we have no way to verify that all the deletions delete
 115   // that same edge.  On this point we must use the Honor System.
 116   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 117   assert(node->_last_del == _last, "must have deleted the edge just produced");
 118   // We liked this deletion, so accept the resulting outcnt and tick.
 119   _outcnt   = node->_outcnt;
 120   _del_tick = node->_del_tick;
 121 }
 122 
 123 void DUIterator_Common::reset(const DUIterator_Common& that) {
 124   if (this == &that)  return;  // ignore assignment to self
 125   if (!_vdui) {
 126     // We need to initialize everything, overwriting garbage values.
 127     _last = that._last;
 128     _vdui = that._vdui;
 129   }
 130   // Note:  It is legal (though odd) for an iterator over some node x
 131   // to be reassigned to iterate over another node y.  Some doubly-nested
 132   // progress loops depend on being able to do this.
 133   const Node* node = that._node;
 134   // Re-initialize everything, except _last.
 135   _node     = node;
 136   _outcnt   = node->_outcnt;
 137   _del_tick = node->_del_tick;
 138 }
 139 
 140 void DUIterator::sample(const Node* node) {
 141   DUIterator_Common::sample(node);      // Initialize the assertion data.
 142   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 143 }
 144 
 145 void DUIterator::verify(const Node* node, bool at_end_ok) {
 146   DUIterator_Common::verify(node, at_end_ok);
 147   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 148 }
 149 
 150 void DUIterator::verify_increment() {
 151   if (_refresh_tick & 1) {
 152     // We have refreshed the index during this loop.
 153     // Fix up _idx to meet asserts.
 154     if (_idx > _outcnt)  _idx = _outcnt;
 155   }
 156   verify(_node, true);
 157 }
 158 
 159 void DUIterator::verify_resync() {
 160   // Note:  We do not assert on _outcnt, because insertions are OK here.
 161   DUIterator_Common::verify_resync();
 162   // Make sure we are still in sync, possibly with no more out-edges:
 163   verify(_node, true);
 164 }
 165 
 166 void DUIterator::reset(const DUIterator& that) {
 167   if (this == &that)  return;  // self assignment is always a no-op
 168   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 169   assert(that._idx          == 0, "assign only the result of Node::outs()");
 170   assert(_idx               == that._idx, "already assigned _idx");
 171   if (!_vdui) {
 172     // We need to initialize everything, overwriting garbage values.
 173     sample(that._node);
 174   } else {
 175     DUIterator_Common::reset(that);
 176     if (_refresh_tick & 1) {
 177       _refresh_tick++;                  // Clear the "was refreshed" flag.
 178     }
 179     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 180   }
 181 }
 182 
 183 void DUIterator::refresh() {
 184   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 185   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 186 }
 187 
 188 void DUIterator::verify_finish() {
 189   // If the loop has killed the node, do not require it to re-run.
 190   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 191   // If this assert triggers, it means that a loop used refresh_out_pos
 192   // to re-synch an iteration index, but the loop did not correctly
 193   // re-run itself, using a "while (progress)" construct.
 194   // This iterator enforces the rule that you must keep trying the loop
 195   // until it "runs clean" without any need for refreshing.
 196   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 197 }
 198 
 199 
 200 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 201   DUIterator_Common::verify(node, at_end_ok);
 202   Node** out    = node->_out;
 203   uint   cnt    = node->_outcnt;
 204   assert(cnt == _outcnt, "no insertions allowed");
 205   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 206   // This last check is carefully designed to work for NO_OUT_ARRAY.
 207 }
 208 
 209 void DUIterator_Fast::verify_limit() {
 210   const Node* node = _node;
 211   verify(node, true);
 212   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 213 }
 214 
 215 void DUIterator_Fast::verify_resync() {
 216   const Node* node = _node;
 217   if (_outp == node->_out + _outcnt) {
 218     // Note that the limit imax, not the pointer i, gets updated with the
 219     // exact count of deletions.  (For the pointer it's always "--i".)
 220     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 221     // This is a limit pointer, with a name like "imax".
 222     // Fudge the _last field so that the common assert will be happy.
 223     _last = (Node*) node->_last_del;
 224     DUIterator_Common::verify_resync();
 225   } else {
 226     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 227     // A normal internal pointer.
 228     DUIterator_Common::verify_resync();
 229     // Make sure we are still in sync, possibly with no more out-edges:
 230     verify(node, true);
 231   }
 232 }
 233 
 234 void DUIterator_Fast::verify_relimit(uint n) {
 235   const Node* node = _node;
 236   assert((int)n > 0, "use imax -= n only with a positive count");
 237   // This must be a limit pointer, with a name like "imax".
 238   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 239   // The reported number of deletions must match what the node saw.
 240   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 241   // Fudge the _last field so that the common assert will be happy.
 242   _last = (Node*) node->_last_del;
 243   DUIterator_Common::verify_resync();
 244 }
 245 
 246 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 247   assert(_outp              == that._outp, "already assigned _outp");
 248   DUIterator_Common::reset(that);
 249 }
 250 
 251 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 252   // at_end_ok means the _outp is allowed to underflow by 1
 253   _outp += at_end_ok;
 254   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 255   _outp -= at_end_ok;
 256   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 257 }
 258 
 259 void DUIterator_Last::verify_limit() {
 260   // Do not require the limit address to be resynched.
 261   //verify(node, true);
 262   assert(_outp == _node->_out, "limit still correct");
 263 }
 264 
 265 void DUIterator_Last::verify_step(uint num_edges) {
 266   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 267   _outcnt   -= num_edges;
 268   _del_tick += num_edges;
 269   // Make sure we are still in sync, possibly with no more out-edges:
 270   const Node* node = _node;
 271   verify(node, true);
 272   assert(node->_last_del == _last, "must have deleted the edge just produced");
 273 }
 274 
 275 #endif //OPTO_DU_ITERATOR_ASSERT
 276 
 277 
 278 #endif //ASSERT
 279 
 280 
 281 // This constant used to initialize _out may be any non-null value.
 282 // The value null is reserved for the top node only.
 283 #define NO_OUT_ARRAY ((Node**)-1)
 284 
 285 // Out-of-line code from node constructors.
 286 // Executed only when extra debug info. is being passed around.
 287 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 288   C->set_node_notes_at(idx, nn);
 289 }
 290 
 291 // Shared initialization code.
 292 inline int Node::Init(int req) {
 293   Compile* C = Compile::current();
 294   int idx = C->next_unique();
 295   NOT_PRODUCT(_igv_idx = C->next_igv_idx());
 296 
 297   // Allocate memory for the necessary number of edges.
 298   if (req > 0) {
 299     // Allocate space for _in array to have double alignment.
 300     _in = (Node **) ((char *) (C->node_arena()->AmallocWords(req * sizeof(void*))));
 301   }
 302   // If there are default notes floating around, capture them:
 303   Node_Notes* nn = C->default_node_notes();
 304   if (nn != nullptr)  init_node_notes(C, idx, nn);
 305 
 306   // Note:  At this point, C is dead,
 307   // and we begin to initialize the new Node.
 308 
 309   _cnt = _max = req;
 310   _outcnt = _outmax = 0;
 311   _class_id = Class_Node;
 312   _flags = 0;
 313   _out = NO_OUT_ARRAY;
 314   return idx;
 315 }
 316 
 317 //------------------------------Node-------------------------------------------
 318 // Create a Node, with a given number of required edges.
 319 Node::Node(uint req)
 320   : _idx(Init(req))
 321 #ifdef ASSERT
 322   , _parse_idx(_idx)
 323 #endif
 324 {
 325   assert( req < Compile::current()->max_node_limit() - NodeLimitFudgeFactor, "Input limit exceeded" );
 326   debug_only( verify_construction() );
 327   NOT_PRODUCT(nodes_created++);
 328   if (req == 0) {
 329     _in = nullptr;
 330   } else {
 331     Node** to = _in;
 332     for(uint i = 0; i < req; i++) {
 333       to[i] = nullptr;
 334     }
 335   }
 336 }
 337 
 338 //------------------------------Node-------------------------------------------
 339 Node::Node(Node *n0)
 340   : _idx(Init(1))
 341 #ifdef ASSERT
 342   , _parse_idx(_idx)
 343 #endif
 344 {
 345   debug_only( verify_construction() );
 346   NOT_PRODUCT(nodes_created++);
 347   assert( is_not_dead(n0), "can not use dead node");
 348   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 349 }
 350 
 351 //------------------------------Node-------------------------------------------
 352 Node::Node(Node *n0, Node *n1)
 353   : _idx(Init(2))
 354 #ifdef ASSERT
 355   , _parse_idx(_idx)
 356 #endif
 357 {
 358   debug_only( verify_construction() );
 359   NOT_PRODUCT(nodes_created++);
 360   assert( is_not_dead(n0), "can not use dead node");
 361   assert( is_not_dead(n1), "can not use dead node");
 362   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 363   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 364 }
 365 
 366 //------------------------------Node-------------------------------------------
 367 Node::Node(Node *n0, Node *n1, Node *n2)
 368   : _idx(Init(3))
 369 #ifdef ASSERT
 370   , _parse_idx(_idx)
 371 #endif
 372 {
 373   debug_only( verify_construction() );
 374   NOT_PRODUCT(nodes_created++);
 375   assert( is_not_dead(n0), "can not use dead node");
 376   assert( is_not_dead(n1), "can not use dead node");
 377   assert( is_not_dead(n2), "can not use dead node");
 378   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 379   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 380   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 381 }
 382 
 383 //------------------------------Node-------------------------------------------
 384 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 385   : _idx(Init(4))
 386 #ifdef ASSERT
 387   , _parse_idx(_idx)
 388 #endif
 389 {
 390   debug_only( verify_construction() );
 391   NOT_PRODUCT(nodes_created++);
 392   assert( is_not_dead(n0), "can not use dead node");
 393   assert( is_not_dead(n1), "can not use dead node");
 394   assert( is_not_dead(n2), "can not use dead node");
 395   assert( is_not_dead(n3), "can not use dead node");
 396   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 397   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 398   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 399   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 400 }
 401 
 402 //------------------------------Node-------------------------------------------
 403 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 404   : _idx(Init(5))
 405 #ifdef ASSERT
 406   , _parse_idx(_idx)
 407 #endif
 408 {
 409   debug_only( verify_construction() );
 410   NOT_PRODUCT(nodes_created++);
 411   assert( is_not_dead(n0), "can not use dead node");
 412   assert( is_not_dead(n1), "can not use dead node");
 413   assert( is_not_dead(n2), "can not use dead node");
 414   assert( is_not_dead(n3), "can not use dead node");
 415   assert( is_not_dead(n4), "can not use dead node");
 416   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 417   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 418   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 419   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 420   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 421 }
 422 
 423 //------------------------------Node-------------------------------------------
 424 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 425                      Node *n4, Node *n5)
 426   : _idx(Init(6))
 427 #ifdef ASSERT
 428   , _parse_idx(_idx)
 429 #endif
 430 {
 431   debug_only( verify_construction() );
 432   NOT_PRODUCT(nodes_created++);
 433   assert( is_not_dead(n0), "can not use dead node");
 434   assert( is_not_dead(n1), "can not use dead node");
 435   assert( is_not_dead(n2), "can not use dead node");
 436   assert( is_not_dead(n3), "can not use dead node");
 437   assert( is_not_dead(n4), "can not use dead node");
 438   assert( is_not_dead(n5), "can not use dead node");
 439   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 440   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 441   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 442   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 443   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 444   _in[5] = n5; if (n5 != nullptr) n5->add_out((Node *)this);
 445 }
 446 
 447 //------------------------------Node-------------------------------------------
 448 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 449                      Node *n4, Node *n5, Node *n6)
 450   : _idx(Init(7))
 451 #ifdef ASSERT
 452   , _parse_idx(_idx)
 453 #endif
 454 {
 455   debug_only( verify_construction() );
 456   NOT_PRODUCT(nodes_created++);
 457   assert( is_not_dead(n0), "can not use dead node");
 458   assert( is_not_dead(n1), "can not use dead node");
 459   assert( is_not_dead(n2), "can not use dead node");
 460   assert( is_not_dead(n3), "can not use dead node");
 461   assert( is_not_dead(n4), "can not use dead node");
 462   assert( is_not_dead(n5), "can not use dead node");
 463   assert( is_not_dead(n6), "can not use dead node");
 464   _in[0] = n0; if (n0 != nullptr) n0->add_out((Node *)this);
 465   _in[1] = n1; if (n1 != nullptr) n1->add_out((Node *)this);
 466   _in[2] = n2; if (n2 != nullptr) n2->add_out((Node *)this);
 467   _in[3] = n3; if (n3 != nullptr) n3->add_out((Node *)this);
 468   _in[4] = n4; if (n4 != nullptr) n4->add_out((Node *)this);
 469   _in[5] = n5; if (n5 != nullptr) n5->add_out((Node *)this);
 470   _in[6] = n6; if (n6 != nullptr) n6->add_out((Node *)this);
 471 }
 472 
 473 #ifdef __clang__
 474 #pragma clang diagnostic pop
 475 #endif
 476 
 477 
 478 //------------------------------clone------------------------------------------
 479 // Clone a Node.
 480 Node *Node::clone() const {
 481   Compile* C = Compile::current();
 482   uint s = size_of();           // Size of inherited Node
 483   Node *n = (Node*)C->node_arena()->AmallocWords(size_of() + _max*sizeof(Node*));
 484   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 485   // Set the new input pointer array
 486   n->_in = (Node**)(((char*)n)+s);
 487   // Cannot share the old output pointer array, so kill it
 488   n->_out = NO_OUT_ARRAY;
 489   // And reset the counters to 0
 490   n->_outcnt = 0;
 491   n->_outmax = 0;
 492   // Unlock this guy, since he is not in any hash table.
 493   debug_only(n->_hash_lock = 0);
 494   // Walk the old node's input list to duplicate its edges
 495   uint i;
 496   for( i = 0; i < len(); i++ ) {
 497     Node *x = in(i);
 498     n->_in[i] = x;
 499     if (x != nullptr) x->add_out(n);
 500   }
 501   if (is_macro()) {
 502     C->add_macro_node(n);
 503   }
 504   if (is_expensive()) {
 505     C->add_expensive_node(n);
 506   }
 507   if (for_post_loop_opts_igvn()) {
 508     // Don't add cloned node to Compile::_for_post_loop_opts_igvn list automatically.
 509     // If it is applicable, it will happen anyway when the cloned node is registered with IGVN.
 510     n->remove_flag(Node::NodeFlags::Flag_for_post_loop_opts_igvn);
 511   }
 512   if (n->is_ParsePredicate()) {
 513     C->add_parse_predicate(n->as_ParsePredicate());
 514   }
 515 
 516   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 517   bs->register_potential_barrier_node(n);
 518 
 519   n->set_idx(C->next_unique()); // Get new unique index as well
 520   NOT_PRODUCT(n->_igv_idx = C->next_igv_idx());
 521   debug_only( n->verify_construction() );
 522   NOT_PRODUCT(nodes_created++);
 523   // Do not patch over the debug_idx of a clone, because it makes it
 524   // impossible to break on the clone's moment of creation.
 525   //debug_only( n->set_debug_idx( debug_idx() ) );
 526 
 527   C->copy_node_notes_to(n, (Node*) this);
 528 
 529   // MachNode clone
 530   uint nopnds;
 531   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 532     MachNode *mach  = n->as_Mach();
 533     MachNode *mthis = this->as_Mach();
 534     // Get address of _opnd_array.
 535     // It should be the same offset since it is the clone of this node.
 536     MachOper **from = mthis->_opnds;
 537     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 538                     pointer_delta((const void*)from,
 539                                   (const void*)(&mthis->_opnds), 1));
 540     mach->_opnds = to;
 541     for ( uint i = 0; i < nopnds; ++i ) {
 542       to[i] = from[i]->clone();
 543     }
 544   }
 545   if (n->is_Call()) {
 546     // CallGenerator is linked to the original node.
 547     CallGenerator* cg = n->as_Call()->generator();
 548     if (cg != nullptr) {
 549       CallGenerator* cloned_cg = cg->with_call_node(n->as_Call());
 550       n->as_Call()->set_generator(cloned_cg);
 551 
 552       C->print_inlining_assert_ready();
 553       C->print_inlining_move_to(cg);
 554       C->print_inlining_update(cloned_cg);
 555     }
 556   }
 557   if (n->is_SafePoint()) {
 558     // Scalar replacement and macro expansion might modify the JVMState.
 559     // Clone it to make sure it's not shared between SafePointNodes.
 560     n->as_SafePoint()->clone_jvms(C);
 561     n->as_SafePoint()->clone_replaced_nodes();
 562   }
 563   if (n->is_InlineType()) {
 564     C->add_inline_type(n);
 565   }
 566   Compile::current()->record_modified_node(n);
 567   return n;                     // Return the clone
 568 }
 569 
 570 //---------------------------setup_is_top--------------------------------------
 571 // Call this when changing the top node, to reassert the invariants
 572 // required by Node::is_top.  See Compile::set_cached_top_node.
 573 void Node::setup_is_top() {
 574   if (this == (Node*)Compile::current()->top()) {
 575     // This node has just become top.  Kill its out array.
 576     _outcnt = _outmax = 0;
 577     _out = nullptr;                           // marker value for top
 578     assert(is_top(), "must be top");
 579   } else {
 580     if (_out == nullptr)  _out = NO_OUT_ARRAY;
 581     assert(!is_top(), "must not be top");
 582   }
 583 }
 584 
 585 //------------------------------~Node------------------------------------------
 586 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 587 void Node::destruct(PhaseValues* phase) {
 588   Compile* compile = (phase != nullptr) ? phase->C : Compile::current();
 589   if (phase != nullptr && phase->is_IterGVN()) {
 590     phase->is_IterGVN()->_worklist.remove(this);
 591   }
 592   // If this is the most recently created node, reclaim its index. Otherwise,
 593   // record the node as dead to keep liveness information accurate.
 594   if ((uint)_idx+1 == compile->unique()) {
 595     compile->set_unique(compile->unique()-1);
 596   } else {
 597     compile->record_dead_node(_idx);
 598   }
 599   // Clear debug info:
 600   Node_Notes* nn = compile->node_notes_at(_idx);
 601   if (nn != nullptr)  nn->clear();
 602   // Walk the input array, freeing the corresponding output edges
 603   _cnt = _max;  // forget req/prec distinction
 604   uint i;
 605   for( i = 0; i < _max; i++ ) {
 606     set_req(i, nullptr);
 607     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 608   }
 609   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 610 
 611   if (is_macro()) {
 612     compile->remove_macro_node(this);
 613   }
 614   if (is_expensive()) {
 615     compile->remove_expensive_node(this);
 616   }
 617   if (Opcode() == Op_Opaque4) {
 618     compile->remove_template_assertion_predicate_opaq(this);
 619   }
 620   if (is_ParsePredicate()) {
 621     compile->remove_parse_predicate(as_ParsePredicate());
 622   }
 623   if (for_post_loop_opts_igvn()) {
 624     compile->remove_from_post_loop_opts_igvn(this);
 625   }
 626   if (is_InlineType()) {
 627     compile->remove_inline_type(this);
 628   }
 629 
 630   if (is_SafePoint()) {
 631     as_SafePoint()->delete_replaced_nodes();
 632 
 633     if (is_CallStaticJava()) {
 634       compile->remove_unstable_if_trap(as_CallStaticJava(), false);
 635     }
 636   }
 637   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 638   bs->unregister_potential_barrier_node(this);
 639 
 640   // See if the input array was allocated just prior to the object
 641   int edge_size = _max*sizeof(void*);
 642   int out_edge_size = _outmax*sizeof(void*);
 643   char *in_array = ((char*)_in);
 644   char *edge_end = in_array + edge_size;
 645   char *out_array = (char*)(_out == NO_OUT_ARRAY? nullptr: _out);
 646   int node_size = size_of();
 647 
 648 #ifdef ASSERT
 649   // We will not actually delete the storage, but we'll make the node unusable.
 650   compile->remove_modified_node(this);
 651   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 652   _in = _out = (Node**) badAddress;
 653   _max = _cnt = _outmax = _outcnt = 0;
 654 #endif
 655 
 656   // Free the output edge array
 657   if (out_edge_size > 0) {
 658     compile->node_arena()->Afree(out_array, out_edge_size);
 659   }
 660 
 661   // Free the input edge array and the node itself
 662   if( edge_end == (char*)this ) {
 663     // It was; free the input array and object all in one hit
 664 #ifndef ASSERT
 665     compile->node_arena()->Afree(in_array, edge_size+node_size);
 666 #endif
 667   } else {
 668     // Free just the input array
 669     compile->node_arena()->Afree(in_array, edge_size);
 670 
 671     // Free just the object
 672 #ifndef ASSERT
 673     compile->node_arena()->Afree(this, node_size);
 674 #endif
 675   }
 676 }
 677 
 678 //------------------------------grow-------------------------------------------
 679 // Grow the input array, making space for more edges
 680 void Node::grow(uint len) {
 681   Arena* arena = Compile::current()->node_arena();
 682   uint new_max = _max;
 683   if( new_max == 0 ) {
 684     _max = 4;
 685     _in = (Node**)arena->Amalloc(4*sizeof(Node*));
 686     Node** to = _in;
 687     to[0] = nullptr;
 688     to[1] = nullptr;
 689     to[2] = nullptr;
 690     to[3] = nullptr;
 691     return;
 692   }
 693   new_max = next_power_of_2(len);
 694   // Trimming to limit allows a uint8 to handle up to 255 edges.
 695   // Previously I was using only powers-of-2 which peaked at 128 edges.
 696   //if( new_max >= limit ) new_max = limit-1;
 697   _in = (Node**)arena->Arealloc(_in, _max*sizeof(Node*), new_max*sizeof(Node*));
 698   Copy::zero_to_bytes(&_in[_max], (new_max-_max)*sizeof(Node*)); // null all new space
 699   _max = new_max;               // Record new max length
 700   // This assertion makes sure that Node::_max is wide enough to
 701   // represent the numerical value of new_max.
 702   assert(_max == new_max && _max > len, "int width of _max is too small");
 703 }
 704 
 705 //-----------------------------out_grow----------------------------------------
 706 // Grow the input array, making space for more edges
 707 void Node::out_grow( uint len ) {
 708   assert(!is_top(), "cannot grow a top node's out array");
 709   Arena* arena = Compile::current()->node_arena();
 710   uint new_max = _outmax;
 711   if( new_max == 0 ) {
 712     _outmax = 4;
 713     _out = (Node **)arena->Amalloc(4*sizeof(Node*));
 714     return;
 715   }
 716   new_max = next_power_of_2(len);
 717   // Trimming to limit allows a uint8 to handle up to 255 edges.
 718   // Previously I was using only powers-of-2 which peaked at 128 edges.
 719   //if( new_max >= limit ) new_max = limit-1;
 720   assert(_out != nullptr && _out != NO_OUT_ARRAY, "out must have sensible value");
 721   _out = (Node**)arena->Arealloc(_out,_outmax*sizeof(Node*),new_max*sizeof(Node*));
 722   //Copy::zero_to_bytes(&_out[_outmax], (new_max-_outmax)*sizeof(Node*)); // null all new space
 723   _outmax = new_max;               // Record new max length
 724   // This assertion makes sure that Node::_max is wide enough to
 725   // represent the numerical value of new_max.
 726   assert(_outmax == new_max && _outmax > len, "int width of _outmax is too small");
 727 }
 728 
 729 #ifdef ASSERT
 730 //------------------------------is_dead----------------------------------------
 731 bool Node::is_dead() const {
 732   // Mach and pinch point nodes may look like dead.
 733   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 734     return false;
 735   for( uint i = 0; i < _max; i++ )
 736     if( _in[i] != nullptr )
 737       return false;
 738   return true;
 739 }
 740 
 741 bool Node::is_not_dead(const Node* n) {
 742   return n == nullptr || !PhaseIterGVN::is_verify_def_use() || !(n->is_dead());
 743 }
 744 
 745 bool Node::is_reachable_from_root() const {
 746   ResourceMark rm;
 747   Unique_Node_List wq;
 748   wq.push((Node*)this);
 749   RootNode* root = Compile::current()->root();
 750   for (uint i = 0; i < wq.size(); i++) {
 751     Node* m = wq.at(i);
 752     if (m == root) {
 753       return true;
 754     }
 755     for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
 756       Node* u = m->fast_out(j);
 757       wq.push(u);
 758     }
 759   }
 760   return false;
 761 }
 762 #endif
 763 
 764 //------------------------------is_unreachable---------------------------------
 765 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 766   assert(!is_Mach(), "doesn't work with MachNodes");
 767   return outcnt() == 0 || igvn.type(this) == Type::TOP || (in(0) != nullptr && in(0)->is_top());
 768 }
 769 
 770 //------------------------------add_req----------------------------------------
 771 // Add a new required input at the end
 772 void Node::add_req( Node *n ) {
 773   assert( is_not_dead(n), "can not use dead node");
 774 
 775   // Look to see if I can move precedence down one without reallocating
 776   if( (_cnt >= _max) || (in(_max-1) != nullptr) )
 777     grow( _max+1 );
 778 
 779   // Find a precedence edge to move
 780   if( in(_cnt) != nullptr ) {   // Next precedence edge is busy?
 781     uint i;
 782     for( i=_cnt; i<_max; i++ )
 783       if( in(i) == nullptr )    // Find the null at end of prec edge list
 784         break;                  // There must be one, since we grew the array
 785     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 786   }
 787   _in[_cnt++] = n;            // Stuff over old prec edge
 788   if (n != nullptr) n->add_out((Node *)this);
 789   Compile::current()->record_modified_node(this);
 790 }
 791 
 792 //---------------------------add_req_batch-------------------------------------
 793 // Add a new required input at the end
 794 void Node::add_req_batch( Node *n, uint m ) {
 795   assert( is_not_dead(n), "can not use dead node");
 796   // check various edge cases
 797   if ((int)m <= 1) {
 798     assert((int)m >= 0, "oob");
 799     if (m != 0)  add_req(n);
 800     return;
 801   }
 802 
 803   // Look to see if I can move precedence down one without reallocating
 804   if( (_cnt+m) > _max || _in[_max-m] )
 805     grow( _max+m );
 806 
 807   // Find a precedence edge to move
 808   if( _in[_cnt] != nullptr ) {  // Next precedence edge is busy?
 809     uint i;
 810     for( i=_cnt; i<_max; i++ )
 811       if( _in[i] == nullptr )   // Find the null at end of prec edge list
 812         break;                  // There must be one, since we grew the array
 813     // Slide all the precs over by m positions (assume #prec << m).
 814     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 815   }
 816 
 817   // Stuff over the old prec edges
 818   for(uint i=0; i<m; i++ ) {
 819     _in[_cnt++] = n;
 820   }
 821 
 822   // Insert multiple out edges on the node.
 823   if (n != nullptr && !n->is_top()) {
 824     for(uint i=0; i<m; i++ ) {
 825       n->add_out((Node *)this);
 826     }
 827   }
 828   Compile::current()->record_modified_node(this);
 829 }
 830 
 831 //------------------------------del_req----------------------------------------
 832 // Delete the required edge and compact the edge array
 833 void Node::del_req( uint idx ) {
 834   assert( idx < _cnt, "oob");
 835   assert( !VerifyHashTableKeys || _hash_lock == 0,
 836           "remove node from hash table before modifying it");
 837   // First remove corresponding def-use edge
 838   Node *n = in(idx);
 839   if (n != nullptr) n->del_out((Node *)this);
 840   _in[idx] = in(--_cnt); // Compact the array
 841   // Avoid spec violation: Gap in prec edges.
 842   close_prec_gap_at(_cnt);
 843   Compile::current()->record_modified_node(this);
 844 }
 845 
 846 //------------------------------del_req_ordered--------------------------------
 847 // Delete the required edge and compact the edge array with preserved order
 848 void Node::del_req_ordered( 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   if (idx < --_cnt) {    // Not last edge ?
 856     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
 857   }
 858   // Avoid spec violation: Gap in prec edges.
 859   close_prec_gap_at(_cnt);
 860   Compile::current()->record_modified_node(this);
 861 }
 862 
 863 //------------------------------ins_req----------------------------------------
 864 // Insert a new required input at the end
 865 void Node::ins_req( uint idx, Node *n ) {
 866   assert( is_not_dead(n), "can not use dead node");
 867   add_req(nullptr);                // Make space
 868   assert( idx < _max, "Must have allocated enough space");
 869   // Slide over
 870   if(_cnt-idx-1 > 0) {
 871     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 872   }
 873   _in[idx] = n;                            // Stuff over old required edge
 874   if (n != nullptr) n->add_out((Node *)this); // Add reciprocal def-use edge
 875   Compile::current()->record_modified_node(this);
 876 }
 877 
 878 //-----------------------------find_edge---------------------------------------
 879 int Node::find_edge(Node* n) {
 880   for (uint i = 0; i < len(); i++) {
 881     if (_in[i] == n)  return i;
 882   }
 883   return -1;
 884 }
 885 
 886 //----------------------------replace_edge-------------------------------------
 887 int Node::replace_edge(Node* old, Node* neww, PhaseGVN* gvn) {
 888   if (old == neww)  return 0;  // nothing to do
 889   uint nrep = 0;
 890   for (uint i = 0; i < len(); i++) {
 891     if (in(i) == old) {
 892       if (i < req()) {
 893         if (gvn != nullptr) {
 894           set_req_X(i, neww, gvn);
 895         } else {
 896           set_req(i, neww);
 897         }
 898       } else {
 899         assert(gvn == nullptr || gvn->is_IterGVN() == nullptr, "no support for igvn here");
 900         assert(find_prec_edge(neww) == -1, "spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx);
 901         set_prec(i, neww);
 902       }
 903       nrep++;
 904     }
 905   }
 906   return nrep;
 907 }
 908 
 909 /**
 910  * Replace input edges in the range pointing to 'old' node.
 911  */
 912 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end, PhaseGVN* gvn) {
 913   if (old == neww)  return 0;  // nothing to do
 914   uint nrep = 0;
 915   for (int i = start; i < end; i++) {
 916     if (in(i) == old) {
 917       set_req_X(i, neww, gvn);
 918       nrep++;
 919     }
 920   }
 921   return nrep;
 922 }
 923 
 924 //-------------------------disconnect_inputs-----------------------------------
 925 // null out all inputs to eliminate incoming Def-Use edges.
 926 void Node::disconnect_inputs(Compile* C) {
 927   // the layout of Node::_in
 928   // r: a required input, null is allowed
 929   // p: a precedence, null values are all at the end
 930   // -----------------------------------
 931   // |r|...|r|p|...|p|null|...|null|
 932   //         |                     |
 933   //         req()                 len()
 934   // -----------------------------------
 935   for (uint i = 0; i < req(); ++i) {
 936     if (in(i) != nullptr) {
 937       set_req(i, nullptr);
 938     }
 939   }
 940 
 941   // Remove precedence edges if any exist
 942   // Note: Safepoints may have precedence edges, even during parsing
 943   for (uint i = len(); i > req(); ) {
 944     rm_prec(--i);  // no-op if _in[i] is null
 945   }
 946 
 947 #ifdef ASSERT
 948   // sanity check
 949   for (uint i = 0; i < len(); ++i) {
 950     assert(_in[i] == nullptr, "disconnect_inputs() failed!");
 951   }
 952 #endif
 953 
 954   // Node::destruct requires all out edges be deleted first
 955   // debug_only(destruct();)   // no reuse benefit expected
 956   C->record_dead_node(_idx);
 957 }
 958 
 959 //-----------------------------uncast---------------------------------------
 960 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 961 // Strip away casting.  (It is depth-limited.)
 962 // Optionally, keep casts with dependencies.
 963 Node* Node::uncast(bool keep_deps) const {
 964   // Should be inline:
 965   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 966   if (is_ConstraintCast()) {
 967     return uncast_helper(this, keep_deps);
 968   } else {
 969     return (Node*) this;
 970   }
 971 }
 972 
 973 // Find out of current node that matches opcode.
 974 Node* Node::find_out_with(int opcode) {
 975   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 976     Node* use = fast_out(i);
 977     if (use->Opcode() == opcode) {
 978       return use;
 979     }
 980   }
 981   return nullptr;
 982 }
 983 
 984 // Return true if the current node has an out that matches opcode.
 985 bool Node::has_out_with(int opcode) {
 986   return (find_out_with(opcode) != nullptr);
 987 }
 988 
 989 // Return true if the current node has an out that matches any of the opcodes.
 990 bool Node::has_out_with(int opcode1, int opcode2, int opcode3, int opcode4) {
 991   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 992       int opcode = fast_out(i)->Opcode();
 993       if (opcode == opcode1 || opcode == opcode2 || opcode == opcode3 || opcode == opcode4) {
 994         return true;
 995       }
 996   }
 997   return false;
 998 }
 999 
1000 
1001 //---------------------------uncast_helper-------------------------------------
1002 Node* Node::uncast_helper(const Node* p, bool keep_deps) {
1003 #ifdef ASSERT
1004   uint depth_count = 0;
1005   const Node* orig_p = p;
1006 #endif
1007 
1008   while (true) {
1009 #ifdef ASSERT
1010     if (depth_count >= K) {
1011       orig_p->dump(4);
1012       if (p != orig_p)
1013         p->dump(1);
1014     }
1015     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
1016 #endif
1017     if (p == nullptr || p->req() != 2) {
1018       break;
1019     } else if (p->is_ConstraintCast()) {
1020       if (keep_deps && p->as_ConstraintCast()->carry_dependency()) {
1021         break; // stop at casts with dependencies
1022       }
1023       p = p->in(1);
1024     } else {
1025       break;
1026     }
1027   }
1028   return (Node*) p;
1029 }
1030 
1031 //------------------------------add_prec---------------------------------------
1032 // Add a new precedence input.  Precedence inputs are unordered, with
1033 // duplicates removed and nulls packed down at the end.
1034 void Node::add_prec( Node *n ) {
1035   assert( is_not_dead(n), "can not use dead node");
1036 
1037   // Check for null at end
1038   if( _cnt >= _max || in(_max-1) )
1039     grow( _max+1 );
1040 
1041   // Find a precedence edge to move
1042   uint i = _cnt;
1043   while( in(i) != nullptr ) {
1044     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
1045     i++;
1046   }
1047   _in[i] = n;                                   // Stuff prec edge over null
1048   if ( n != nullptr) n->add_out((Node *)this);  // Add mirror edge
1049 
1050 #ifdef ASSERT
1051   while ((++i)<_max) { assert(_in[i] == nullptr, "spec violation: Gap in prec edges (node %d)", _idx); }
1052 #endif
1053   Compile::current()->record_modified_node(this);
1054 }
1055 
1056 //------------------------------rm_prec----------------------------------------
1057 // Remove a precedence input.  Precedence inputs are unordered, with
1058 // duplicates removed and nulls packed down at the end.
1059 void Node::rm_prec( uint j ) {
1060   assert(j < _max, "oob: i=%d, _max=%d", j, _max);
1061   assert(j >= _cnt, "not a precedence edge");
1062   if (_in[j] == nullptr) return;   // Avoid spec violation: Gap in prec edges.
1063   _in[j]->del_out((Node *)this);
1064   close_prec_gap_at(j);
1065   Compile::current()->record_modified_node(this);
1066 }
1067 
1068 //------------------------------size_of----------------------------------------
1069 uint Node::size_of() const { return sizeof(*this); }
1070 
1071 //------------------------------ideal_reg--------------------------------------
1072 uint Node::ideal_reg() const { return 0; }
1073 
1074 //------------------------------jvms-------------------------------------------
1075 JVMState* Node::jvms() const { return nullptr; }
1076 
1077 #ifdef ASSERT
1078 //------------------------------jvms-------------------------------------------
1079 bool Node::verify_jvms(const JVMState* using_jvms) const {
1080   for (JVMState* jvms = this->jvms(); jvms != nullptr; jvms = jvms->caller()) {
1081     if (jvms == using_jvms)  return true;
1082   }
1083   return false;
1084 }
1085 
1086 //------------------------------init_NodeProperty------------------------------
1087 void Node::init_NodeProperty() {
1088   assert(_max_classes <= max_juint, "too many NodeProperty classes");
1089   assert(max_flags() <= max_juint, "too many NodeProperty flags");
1090 }
1091 
1092 //-----------------------------max_flags---------------------------------------
1093 juint Node::max_flags() {
1094   return (PD::_last_flag << 1) - 1; // allow flags combination
1095 }
1096 #endif
1097 
1098 //------------------------------format-----------------------------------------
1099 // Print as assembly
1100 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1101 //------------------------------emit-------------------------------------------
1102 // Emit bytes starting at parameter 'ptr'.
1103 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
1104 //------------------------------size-------------------------------------------
1105 // Size of instruction in bytes
1106 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1107 
1108 //------------------------------CFG Construction-------------------------------
1109 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1110 // Goto and Return.
1111 const Node *Node::is_block_proj() const { return 0; }
1112 
1113 // Minimum guaranteed type
1114 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1115 
1116 
1117 //------------------------------raise_bottom_type------------------------------
1118 // Get the worst-case Type output for this Node.
1119 void Node::raise_bottom_type(const Type* new_type) {
1120   if (is_Type()) {
1121     TypeNode *n = this->as_Type();
1122     if (VerifyAliases) {
1123       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1124     }
1125     n->set_type(new_type);
1126   } else if (is_Load()) {
1127     LoadNode *n = this->as_Load();
1128     if (VerifyAliases) {
1129       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1130     }
1131     n->set_type(new_type);
1132   }
1133 }
1134 
1135 //------------------------------Identity---------------------------------------
1136 // Return a node that the given node is equivalent to.
1137 Node* Node::Identity(PhaseGVN* phase) {
1138   return this;                  // Default to no identities
1139 }
1140 
1141 //------------------------------Value------------------------------------------
1142 // Compute a new Type for a node using the Type of the inputs.
1143 const Type* Node::Value(PhaseGVN* phase) const {
1144   return bottom_type();         // Default to worst-case Type
1145 }
1146 
1147 //------------------------------Ideal------------------------------------------
1148 //
1149 // 'Idealize' the graph rooted at this Node.
1150 //
1151 // In order to be efficient and flexible there are some subtle invariants
1152 // these Ideal calls need to hold.  Running with '-XX:VerifyIterativeGVN=1' checks
1153 // these invariants, although its too slow to have on by default.  If you are
1154 // hacking an Ideal call, be sure to test with '-XX:VerifyIterativeGVN=1'
1155 //
1156 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1157 // pointer.  If ANY change is made, it must return the root of the reshaped
1158 // graph - even if the root is the same Node.  Example: swapping the inputs
1159 // to an AddINode gives the same answer and same root, but you still have to
1160 // return the 'this' pointer instead of null.
1161 //
1162 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1163 // Identity call to return an old Node; basically if Identity can find
1164 // another Node have the Ideal call make no change and return null.
1165 // Example: AddINode::Ideal must check for add of zero; in this case it
1166 // returns null instead of doing any graph reshaping.
1167 //
1168 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1169 // sharing there may be other users of the old Nodes relying on their current
1170 // semantics.  Modifying them will break the other users.
1171 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1172 // "X+3" unchanged in case it is shared.
1173 //
1174 // If you modify the 'this' pointer's inputs, you should use
1175 // 'set_req'.  If you are making a new Node (either as the new root or
1176 // some new internal piece) you may use 'init_req' to set the initial
1177 // value.  You can make a new Node with either 'new' or 'clone'.  In
1178 // either case, def-use info is correctly maintained.
1179 //
1180 // Example: reshape "(X+3)+4" into "X+7":
1181 //    set_req(1, in(1)->in(1));
1182 //    set_req(2, phase->intcon(7));
1183 //    return this;
1184 // Example: reshape "X*4" into "X<<2"
1185 //    return new LShiftINode(in(1), phase->intcon(2));
1186 //
1187 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1188 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1189 //    Node *shift=phase->transform(new LShiftINode(in(1),phase->intcon(5)));
1190 //    return new AddINode(shift, in(1));
1191 //
1192 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1193 // These forms are faster than 'phase->transform(new ConNode())' and Do
1194 // The Right Thing with def-use info.
1195 //
1196 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1197 // graph uses the 'this' Node it must be the root.  If you want a Node with
1198 // the same Opcode as the 'this' pointer use 'clone'.
1199 //
1200 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1201   return nullptr;                  // Default to being Ideal already
1202 }
1203 
1204 // Some nodes have specific Ideal subgraph transformations only if they are
1205 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1206 // for the transformations to happen.
1207 bool Node::has_special_unique_user() const {
1208   assert(outcnt() == 1, "match only for unique out");
1209   Node* n = unique_out();
1210   int op  = Opcode();
1211   if (this->is_Store()) {
1212     // Condition for back-to-back stores folding.
1213     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1214   } else if (this->is_Load() || this->is_DecodeN() || this->is_Phi()) {
1215     // Condition for removing an unused LoadNode or DecodeNNode from the MemBarAcquire precedence input
1216     return n->Opcode() == Op_MemBarAcquire;
1217   } else if (op == Op_AddL) {
1218     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1219     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1220   } else if (op == Op_SubI || op == Op_SubL) {
1221     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1222     return n->Opcode() == op && n->in(2) == this;
1223   } else if (is_If() && (n->is_IfFalse() || n->is_IfTrue())) {
1224     // See IfProjNode::Identity()
1225     return true;
1226   } else if ((is_IfFalse() || is_IfTrue()) && n->is_If()) {
1227     // See IfNode::fold_compares
1228     return true;
1229   } else {
1230     return false;
1231   }
1232 };
1233 
1234 //--------------------------find_exact_control---------------------------------
1235 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1236 Node* Node::find_exact_control(Node* ctrl) {
1237   if (ctrl == nullptr && this->is_Region())
1238     ctrl = this->as_Region()->is_copy();
1239 
1240   if (ctrl != nullptr && ctrl->is_CatchProj()) {
1241     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1242       ctrl = ctrl->in(0);
1243     if (ctrl != nullptr && !ctrl->is_top())
1244       ctrl = ctrl->in(0);
1245   }
1246 
1247   if (ctrl != nullptr && ctrl->is_Proj())
1248     ctrl = ctrl->in(0);
1249 
1250   return ctrl;
1251 }
1252 
1253 //--------------------------dominates------------------------------------------
1254 // Helper function for MemNode::all_controls_dominate().
1255 // Check if 'this' control node dominates or equal to 'sub' control node.
1256 // We already know that if any path back to Root or Start reaches 'this',
1257 // then all paths so, so this is a simple search for one example,
1258 // not an exhaustive search for a counterexample.
1259 bool Node::dominates(Node* sub, Node_List &nlist) {
1260   assert(this->is_CFG(), "expecting control");
1261   assert(sub != nullptr && sub->is_CFG(), "expecting control");
1262 
1263   // detect dead cycle without regions
1264   int iterations_without_region_limit = DominatorSearchLimit;
1265 
1266   Node* orig_sub = sub;
1267   Node* dom      = this;
1268   bool  met_dom  = false;
1269   nlist.clear();
1270 
1271   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1272   // After seeing 'dom', continue up to Root or Start.
1273   // If we hit a region (backward split point), it may be a loop head.
1274   // Keep going through one of the region's inputs.  If we reach the
1275   // same region again, go through a different input.  Eventually we
1276   // will either exit through the loop head, or give up.
1277   // (If we get confused, break out and return a conservative 'false'.)
1278   while (sub != nullptr) {
1279     if (sub->is_top())  break; // Conservative answer for dead code.
1280     if (sub == dom) {
1281       if (nlist.size() == 0) {
1282         // No Region nodes except loops were visited before and the EntryControl
1283         // path was taken for loops: it did not walk in a cycle.
1284         return true;
1285       } else if (met_dom) {
1286         break;          // already met before: walk in a cycle
1287       } else {
1288         // Region nodes were visited. Continue walk up to Start or Root
1289         // to make sure that it did not walk in a cycle.
1290         met_dom = true; // first time meet
1291         iterations_without_region_limit = DominatorSearchLimit; // Reset
1292      }
1293     }
1294     if (sub->is_Start() || sub->is_Root()) {
1295       // Success if we met 'dom' along a path to Start or Root.
1296       // We assume there are no alternative paths that avoid 'dom'.
1297       // (This assumption is up to the caller to ensure!)
1298       return met_dom;
1299     }
1300     Node* up = sub->in(0);
1301     // Normalize simple pass-through regions and projections:
1302     up = sub->find_exact_control(up);
1303     // If sub == up, we found a self-loop.  Try to push past it.
1304     if (sub == up && sub->is_Loop()) {
1305       // Take loop entry path on the way up to 'dom'.
1306       up = sub->in(1); // in(LoopNode::EntryControl);
1307     } else if (sub == up && sub->is_Region() && sub->req() == 2) {
1308       // Take in(1) path on the way up to 'dom' for regions with only one input
1309       up = sub->in(1);
1310     } else if (sub == up && sub->is_Region()) {
1311       // Try both paths for Regions with 2 input paths (it may be a loop head).
1312       // It could give conservative 'false' answer without information
1313       // which region's input is the entry path.
1314       iterations_without_region_limit = DominatorSearchLimit; // Reset
1315 
1316       bool region_was_visited_before = false;
1317       // Was this Region node visited before?
1318       // If so, we have reached it because we accidentally took a
1319       // loop-back edge from 'sub' back into the body of the loop,
1320       // and worked our way up again to the loop header 'sub'.
1321       // So, take the first unexplored path on the way up to 'dom'.
1322       for (int j = nlist.size() - 1; j >= 0; j--) {
1323         intptr_t ni = (intptr_t)nlist.at(j);
1324         Node* visited = (Node*)(ni & ~1);
1325         bool  visited_twice_already = ((ni & 1) != 0);
1326         if (visited == sub) {
1327           if (visited_twice_already) {
1328             // Visited 2 paths, but still stuck in loop body.  Give up.
1329             return false;
1330           }
1331           // The Region node was visited before only once.
1332           // (We will repush with the low bit set, below.)
1333           nlist.remove(j);
1334           // We will find a new edge and re-insert.
1335           region_was_visited_before = true;
1336           break;
1337         }
1338       }
1339 
1340       // Find an incoming edge which has not been seen yet; walk through it.
1341       assert(up == sub, "");
1342       uint skip = region_was_visited_before ? 1 : 0;
1343       for (uint i = 1; i < sub->req(); i++) {
1344         Node* in = sub->in(i);
1345         if (in != nullptr && !in->is_top() && in != sub) {
1346           if (skip == 0) {
1347             up = in;
1348             break;
1349           }
1350           --skip;               // skip this nontrivial input
1351         }
1352       }
1353 
1354       // Set 0 bit to indicate that both paths were taken.
1355       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1356     }
1357 
1358     if (up == sub) {
1359       break;    // some kind of tight cycle
1360     }
1361     if (up == orig_sub && met_dom) {
1362       // returned back after visiting 'dom'
1363       break;    // some kind of cycle
1364     }
1365     if (--iterations_without_region_limit < 0) {
1366       break;    // dead cycle
1367     }
1368     sub = up;
1369   }
1370 
1371   // Did not meet Root or Start node in pred. chain.
1372   // Conservative answer for dead code.
1373   return false;
1374 }
1375 
1376 //------------------------------remove_dead_region-----------------------------
1377 // This control node is dead.  Follow the subgraph below it making everything
1378 // using it dead as well.  This will happen normally via the usual IterGVN
1379 // worklist but this call is more efficient.  Do not update use-def info
1380 // inside the dead region, just at the borders.
1381 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1382   // Con's are a popular node to re-hit in the hash table again.
1383   if( dead->is_Con() ) return;
1384 
1385   ResourceMark rm;
1386   Node_List nstack;
1387   VectorSet dead_set; // notify uses only once
1388 
1389   Node *top = igvn->C->top();
1390   nstack.push(dead);
1391   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1392 
1393   while (nstack.size() > 0) {
1394     dead = nstack.pop();
1395     if (!dead_set.test_set(dead->_idx)) {
1396       // If dead has any live uses, those are now still attached. Notify them before we lose them.
1397       igvn->add_users_to_worklist(dead);
1398     }
1399     if (dead->Opcode() == Op_SafePoint) {
1400       dead->as_SafePoint()->disconnect_from_root(igvn);
1401     }
1402     if (dead->outcnt() > 0) {
1403       // Keep dead node on stack until all uses are processed.
1404       nstack.push(dead);
1405       // For all Users of the Dead...    ;-)
1406       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1407         Node* use = dead->last_out(k);
1408         igvn->hash_delete(use);       // Yank from hash table prior to mod
1409         if (use->in(0) == dead) {     // Found another dead node
1410           assert (!use->is_Con(), "Control for Con node should be Root node.");
1411           use->set_req(0, top);       // Cut dead edge to prevent processing
1412           nstack.push(use);           // the dead node again.
1413         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1414                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1415                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1416           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1417           use->set_req(0, top);       // Cut self edge
1418           nstack.push(use);
1419         } else {                      // Else found a not-dead user
1420           // Dead if all inputs are top or null
1421           bool dead_use = !use->is_Root(); // Keep empty graph alive
1422           for (uint j = 1; j < use->req(); j++) {
1423             Node* in = use->in(j);
1424             if (in == dead) {         // Turn all dead inputs into TOP
1425               use->set_req(j, top);
1426             } else if (in != nullptr && !in->is_top()) {
1427               dead_use = false;
1428             }
1429           }
1430           if (dead_use) {
1431             if (use->is_Region()) {
1432               use->set_req(0, top);   // Cut self edge
1433             }
1434             nstack.push(use);
1435           } else {
1436             igvn->_worklist.push(use);
1437           }
1438         }
1439         // Refresh the iterator, since any number of kills might have happened.
1440         k = dead->last_outs(kmin);
1441       }
1442     } else { // (dead->outcnt() == 0)
1443       // Done with outputs.
1444       igvn->hash_delete(dead);
1445       igvn->_worklist.remove(dead);
1446       igvn->set_type(dead, Type::TOP);
1447       // Kill all inputs to the dead guy
1448       for (uint i=0; i < dead->req(); i++) {
1449         Node *n = dead->in(i);      // Get input to dead guy
1450         if (n != nullptr && !n->is_top()) { // Input is valid?
1451           dead->set_req(i, top);    // Smash input away
1452           if (n->outcnt() == 0) {   // Input also goes dead?
1453             if (!n->is_Con())
1454               nstack.push(n);       // Clear it out as well
1455           } else if (n->outcnt() == 1 &&
1456                      n->has_special_unique_user()) {
1457             igvn->add_users_to_worklist( n );
1458           } else if (n->outcnt() <= 2 && n->is_Store()) {
1459             // Push store's uses on worklist to enable folding optimization for
1460             // store/store and store/load to the same address.
1461             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1462             // and remove_globally_dead_node().
1463             igvn->add_users_to_worklist( n );
1464           } else {
1465             BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, n);
1466           }
1467         }
1468       }
1469       igvn->C->remove_useless_node(dead);
1470     } // (dead->outcnt() == 0)
1471   }   // while (nstack.size() > 0) for outputs
1472   return;
1473 }
1474 
1475 //------------------------------remove_dead_region-----------------------------
1476 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1477   Node *n = in(0);
1478   if( !n ) return false;
1479   // Lost control into this guy?  I.e., it became unreachable?
1480   // Aggressively kill all unreachable code.
1481   if (can_reshape && n->is_top()) {
1482     kill_dead_code(this, phase->is_IterGVN());
1483     return false; // Node is dead.
1484   }
1485 
1486   if( n->is_Region() && n->as_Region()->is_copy() ) {
1487     Node *m = n->nonnull_req();
1488     set_req(0, m);
1489     return true;
1490   }
1491   return false;
1492 }
1493 
1494 //------------------------------hash-------------------------------------------
1495 // Hash function over Nodes.
1496 uint Node::hash() const {
1497   uint sum = 0;
1498   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1499     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded nulls
1500   return (sum>>2) + _cnt + Opcode();
1501 }
1502 
1503 //------------------------------cmp--------------------------------------------
1504 // Compare special parts of simple Nodes
1505 bool Node::cmp( const Node &n ) const {
1506   return true;                  // Must be same
1507 }
1508 
1509 //------------------------------rematerialize-----------------------------------
1510 // Should we clone rather than spill this instruction?
1511 bool Node::rematerialize() const {
1512   if ( is_Mach() )
1513     return this->as_Mach()->rematerialize();
1514   else
1515     return (_flags & Flag_rematerialize) != 0;
1516 }
1517 
1518 //------------------------------needs_anti_dependence_check---------------------
1519 // Nodes which use memory without consuming it, hence need antidependences.
1520 bool Node::needs_anti_dependence_check() const {
1521   if (req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0) {
1522     return false;
1523   }
1524   return in(1)->bottom_type()->has_memory();
1525 }
1526 
1527 // Get an integer constant from a ConNode (or CastIINode).
1528 // Return a default value if there is no apparent constant here.
1529 const TypeInt* Node::find_int_type() const {
1530   if (this->is_Type()) {
1531     return this->as_Type()->type()->isa_int();
1532   } else if (this->is_Con()) {
1533     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1534     return this->bottom_type()->isa_int();
1535   }
1536   return nullptr;
1537 }
1538 
1539 const TypeInteger* Node::find_integer_type(BasicType bt) const {
1540   if (this->is_Type()) {
1541     return this->as_Type()->type()->isa_integer(bt);
1542   } else if (this->is_Con()) {
1543     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1544     return this->bottom_type()->isa_integer(bt);
1545   }
1546   return nullptr;
1547 }
1548 
1549 // Get a pointer constant from a ConstNode.
1550 // Returns the constant if it is a pointer ConstNode
1551 intptr_t Node::get_ptr() const {
1552   assert( Opcode() == Op_ConP, "" );
1553   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1554 }
1555 
1556 // Get a narrow oop constant from a ConNNode.
1557 intptr_t Node::get_narrowcon() const {
1558   assert( Opcode() == Op_ConN, "" );
1559   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1560 }
1561 
1562 // Get a long constant from a ConNode.
1563 // Return a default value if there is no apparent constant here.
1564 const TypeLong* Node::find_long_type() const {
1565   if (this->is_Type()) {
1566     return this->as_Type()->type()->isa_long();
1567   } else if (this->is_Con()) {
1568     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1569     return this->bottom_type()->isa_long();
1570   }
1571   return nullptr;
1572 }
1573 
1574 
1575 /**
1576  * Return a ptr type for nodes which should have it.
1577  */
1578 const TypePtr* Node::get_ptr_type() const {
1579   const TypePtr* tp = this->bottom_type()->make_ptr();
1580 #ifdef ASSERT
1581   if (tp == nullptr) {
1582     this->dump(1);
1583     assert((tp != nullptr), "unexpected node type");
1584   }
1585 #endif
1586   return tp;
1587 }
1588 
1589 // Get a double constant from a ConstNode.
1590 // Returns the constant if it is a double ConstNode
1591 jdouble Node::getd() const {
1592   assert( Opcode() == Op_ConD, "" );
1593   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1594 }
1595 
1596 // Get a float constant from a ConstNode.
1597 // Returns the constant if it is a float ConstNode
1598 jfloat Node::getf() const {
1599   assert( Opcode() == Op_ConF, "" );
1600   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1601 }
1602 
1603 #ifndef PRODUCT
1604 
1605 // Call this from debugger:
1606 Node* old_root() {
1607   Matcher* matcher = Compile::current()->matcher();
1608   if (matcher != nullptr) {
1609     Node* new_root = Compile::current()->root();
1610     Node* old_root = matcher->find_old_node(new_root);
1611     if (old_root != nullptr) {
1612       return old_root;
1613     }
1614   }
1615   tty->print("old_root: not found.\n");
1616   return nullptr;
1617 }
1618 
1619 // BFS traverse all reachable nodes from start, call callback on them
1620 template <typename Callback>
1621 void visit_nodes(Node* start, Callback callback, bool traverse_output, bool only_ctrl) {
1622   Unique_Mixed_Node_List worklist;
1623   worklist.add(start);
1624   for (uint i = 0; i < worklist.size(); i++) {
1625     Node* n = worklist[i];
1626     callback(n);
1627     for (uint i = 0; i < n->len(); i++) {
1628       if (!only_ctrl || n->is_Region() || (n->Opcode() == Op_Root) || (i == TypeFunc::Control)) {
1629         // If only_ctrl is set: Add regions, the root node, or control inputs only
1630         worklist.add(n->in(i));
1631       }
1632     }
1633     if (traverse_output && !only_ctrl) {
1634       for (uint i = 0; i < n->outcnt(); i++) {
1635         worklist.add(n->raw_out(i));
1636       }
1637     }
1638   }
1639 }
1640 
1641 // BFS traverse from start, return node with idx
1642 Node* find_node_by_idx(Node* start, uint idx, bool traverse_output, bool only_ctrl) {
1643   ResourceMark rm;
1644   Node* result = nullptr;
1645   auto callback = [&] (Node* n) {
1646     if (n->_idx == idx) {
1647       if (result != nullptr) {
1648         tty->print("find_node_by_idx: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1649           (uintptr_t)result, (uintptr_t)n, idx);
1650       }
1651       result = n;
1652     }
1653   };
1654   visit_nodes(start, callback, traverse_output, only_ctrl);
1655   return result;
1656 }
1657 
1658 int node_idx_cmp(const Node** n1, const Node** n2) {
1659   return (*n1)->_idx - (*n2)->_idx;
1660 }
1661 
1662 void find_nodes_by_name(Node* start, const char* name) {
1663   ResourceMark rm;
1664   GrowableArray<const Node*> ns;
1665   auto callback = [&] (const Node* n) {
1666     if (StringUtils::is_star_match(name, n->Name())) {
1667       ns.push(n);
1668     }
1669   };
1670   visit_nodes(start, callback, true, false);
1671   ns.sort(node_idx_cmp);
1672   for (int i = 0; i < ns.length(); i++) {
1673     ns.at(i)->dump();
1674   }
1675 }
1676 
1677 void find_nodes_by_dump(Node* start, const char* pattern) {
1678   ResourceMark rm;
1679   GrowableArray<const Node*> ns;
1680   auto callback = [&] (const Node* n) {
1681     stringStream stream;
1682     n->dump("", false, &stream);
1683     if (StringUtils::is_star_match(pattern, stream.base())) {
1684       ns.push(n);
1685     }
1686   };
1687   visit_nodes(start, callback, true, false);
1688   ns.sort(node_idx_cmp);
1689   for (int i = 0; i < ns.length(); i++) {
1690     ns.at(i)->dump();
1691   }
1692 }
1693 
1694 // call from debugger: find node with name pattern in new/current graph
1695 // name can contain "*" in match pattern to match any characters
1696 // the matching is case insensitive
1697 void find_nodes_by_name(const char* name) {
1698   Node* root = Compile::current()->root();
1699   find_nodes_by_name(root, name);
1700 }
1701 
1702 // call from debugger: find node with name pattern in old graph
1703 // name can contain "*" in match pattern to match any characters
1704 // the matching is case insensitive
1705 void find_old_nodes_by_name(const char* name) {
1706   Node* root = old_root();
1707   find_nodes_by_name(root, name);
1708 }
1709 
1710 // call from debugger: find node with dump pattern in new/current graph
1711 // can contain "*" in match pattern to match any characters
1712 // the matching is case insensitive
1713 void find_nodes_by_dump(const char* pattern) {
1714   Node* root = Compile::current()->root();
1715   find_nodes_by_dump(root, pattern);
1716 }
1717 
1718 // call from debugger: find node with name pattern in old graph
1719 // can contain "*" in match pattern to match any characters
1720 // the matching is case insensitive
1721 void find_old_nodes_by_dump(const char* pattern) {
1722   Node* root = old_root();
1723   find_nodes_by_dump(root, pattern);
1724 }
1725 
1726 // Call this from debugger, search in same graph as n:
1727 Node* find_node(Node* n, const int idx) {
1728   return n->find(idx);
1729 }
1730 
1731 // Call this from debugger, search in new nodes:
1732 Node* find_node(const int idx) {
1733   return Compile::current()->root()->find(idx);
1734 }
1735 
1736 // Call this from debugger, search in old nodes:
1737 Node* find_old_node(const int idx) {
1738   Node* root = old_root();
1739   return (root == nullptr) ? nullptr : root->find(idx);
1740 }
1741 
1742 // Call this from debugger, search in same graph as n:
1743 Node* find_ctrl(Node* n, const int idx) {
1744   return n->find_ctrl(idx);
1745 }
1746 
1747 // Call this from debugger, search in new nodes:
1748 Node* find_ctrl(const int idx) {
1749   return Compile::current()->root()->find_ctrl(idx);
1750 }
1751 
1752 // Call this from debugger, search in old nodes:
1753 Node* find_old_ctrl(const int idx) {
1754   Node* root = old_root();
1755   return (root == nullptr) ? nullptr : root->find_ctrl(idx);
1756 }
1757 
1758 //------------------------------find_ctrl--------------------------------------
1759 // Find an ancestor to this node in the control history with given _idx
1760 Node* Node::find_ctrl(int idx) {
1761   return find(idx, true);
1762 }
1763 
1764 //------------------------------find-------------------------------------------
1765 // Tries to find the node with the index |idx| starting from this node. If idx is negative,
1766 // the search also includes forward (out) edges. Returns null if not found.
1767 // If only_ctrl is set, the search will only be done on control nodes. Returns null if
1768 // not found or if the node to be found is not a control node (search will not find it).
1769 Node* Node::find(const int idx, bool only_ctrl) {
1770   ResourceMark rm;
1771   return find_node_by_idx(this, abs(idx), (idx < 0), only_ctrl);
1772 }
1773 
1774 class PrintBFS {
1775 public:
1776   PrintBFS(const Node* start, const int max_distance, const Node* target, const char* options, outputStream* st)
1777   : _start(start), _max_distance(max_distance), _target(target), _options(options), _output(st),
1778     _dcc(this), _info_uid(cmpkey, hashkey) {}
1779 
1780   void run();
1781 private:
1782   // pipeline steps
1783   bool configure();
1784   void collect();
1785   void select();
1786   void select_all();
1787   void select_all_paths();
1788   void select_shortest_path();
1789   void sort();
1790   void print();
1791 
1792   // inputs
1793   const Node* _start;
1794   const int _max_distance;
1795   const Node* _target;
1796   const char* _options;
1797   outputStream* _output;
1798 
1799   // options
1800   bool _traverse_inputs = false;
1801   bool _traverse_outputs = false;
1802   struct Filter {
1803     bool _control = false;
1804     bool _memory = false;
1805     bool _data = false;
1806     bool _mixed = false;
1807     bool _other = false;
1808     bool is_empty() const {
1809       return !(_control || _memory || _data || _mixed || _other);
1810     }
1811     void set_all() {
1812       _control = true;
1813       _memory = true;
1814       _data = true;
1815       _mixed = true;
1816       _other = true;
1817     }
1818     // Check if the filter accepts the node. Go by the type categories, but also all CFG nodes
1819     // are considered to have control.
1820     bool accepts(const Node* n) {
1821       const Type* t = n->bottom_type();
1822       return ( _data    &&  t->has_category(Type::Category::Data)                    ) ||
1823              ( _memory  &&  t->has_category(Type::Category::Memory)                  ) ||
1824              ( _mixed   &&  t->has_category(Type::Category::Mixed)                   ) ||
1825              ( _control && (t->has_category(Type::Category::Control) || n->is_CFG()) ) ||
1826              ( _other   &&  t->has_category(Type::Category::Other)                   );
1827     }
1828   };
1829   Filter _filter_visit;
1830   Filter _filter_boundary;
1831   bool _sort_idx = false;
1832   bool _all_paths = false;
1833   bool _use_color = false;
1834   bool _print_blocks = false;
1835   bool _print_old = false;
1836   bool _dump_only = false;
1837   void print_options_help(bool print_examples);
1838   bool parse_options();
1839 
1840 public:
1841   class DumpConfigColored : public Node::DumpConfig {
1842   public:
1843     DumpConfigColored(PrintBFS* bfs) : _bfs(bfs) {};
1844     virtual void pre_dump(outputStream* st, const Node* n);
1845     virtual void post_dump(outputStream* st);
1846   private:
1847     PrintBFS* _bfs;
1848   };
1849 private:
1850   DumpConfigColored _dcc;
1851 
1852   // node info
1853   static Node* old_node(const Node* n); // mach node -> prior IR node
1854   void print_node_idx(const Node* n);
1855   void print_block_id(const Block* b);
1856   void print_node_block(const Node* n); // _pre_order, head idx, _idom, _dom_depth
1857 
1858   // traversal data structures
1859   GrowableArray<const Node*> _worklist; // BFS queue
1860   void maybe_traverse(const Node* src, const Node* dst);
1861 
1862   // node info annotation
1863   class Info {
1864   public:
1865     Info() : Info(nullptr, 0) {};
1866     Info(const Node* node, int distance)
1867       : _node(node), _distance_from_start(distance) {};
1868     const Node* node() const { return _node; };
1869     int distance() const { return _distance_from_start; };
1870     int distance_from_target() const { return _distance_from_target; }
1871     void set_distance_from_target(int d) { _distance_from_target = d; }
1872     GrowableArray<const Node*> edge_bwd; // pointing toward _start
1873     bool is_marked() const { return _mark; } // marked to keep during select
1874     void set_mark() { _mark = true; }
1875   private:
1876     const Node* _node;
1877     int _distance_from_start; // distance from _start
1878     int _distance_from_target = 0; // distance from _target if _all_paths
1879     bool _mark = false;
1880   };
1881   Dict _info_uid;            // Node -> uid
1882   GrowableArray<Info> _info; // uid  -> info
1883 
1884   Info* find_info(const Node* n) {
1885     size_t uid = (size_t)_info_uid[n];
1886     if (uid == 0) {
1887       return nullptr;
1888     }
1889     return &_info.at((int)uid);
1890   }
1891 
1892   void make_info(const Node* node, const int distance) {
1893     assert(find_info(node) == nullptr, "node does not yet have info");
1894     size_t uid = _info.length() + 1;
1895     _info_uid.Insert((void*)node, (void*)uid);
1896     _info.at_put_grow((int)uid, Info(node, distance));
1897     assert(find_info(node)->node() == node, "stored correct node");
1898   };
1899 
1900   // filled by sort, printed by print
1901   GrowableArray<const Node*> _print_list;
1902 
1903   // print header + node table
1904   void print_header() const;
1905   void print_node(const Node* n);
1906 };
1907 
1908 void PrintBFS::run() {
1909   if (!configure()) {
1910     return;
1911   }
1912   collect();
1913   select();
1914   sort();
1915   print();
1916 }
1917 
1918 // set up configuration for BFS and print
1919 bool PrintBFS::configure() {
1920   if (_max_distance < 0) {
1921     _output->print_cr("dump_bfs: max_distance must be non-negative!");
1922     return false;
1923   }
1924   return parse_options();
1925 }
1926 
1927 // BFS traverse according to configuration, fill worklist and info
1928 void PrintBFS::collect() {
1929   maybe_traverse(_start, _start);
1930   int pos = 0;
1931   while (pos < _worklist.length()) {
1932     const Node* n = _worklist.at(pos++); // next node to traverse
1933     Info* info = find_info(n);
1934     if (!_filter_visit.accepts(n) && n != _start) {
1935       continue; // we hit boundary, do not traverse further
1936     }
1937     if (n != _start && n->is_Root()) {
1938       continue; // traversing through root node would lead to unrelated nodes
1939     }
1940     if (_traverse_inputs && _max_distance > info->distance()) {
1941       for (uint i = 0; i < n->req(); i++) {
1942         maybe_traverse(n, n->in(i));
1943       }
1944     }
1945     if (_traverse_outputs && _max_distance > info->distance()) {
1946       for (uint i = 0; i < n->outcnt(); i++) {
1947         maybe_traverse(n, n->raw_out(i));
1948       }
1949     }
1950   }
1951 }
1952 
1953 // go through work list, mark those that we want to print
1954 void PrintBFS::select() {
1955   if (_target == nullptr ) {
1956     select_all();
1957   } else {
1958     if (find_info(_target) == nullptr) {
1959       _output->print_cr("Could not find target in BFS.");
1960       return;
1961     }
1962     if (_all_paths) {
1963       select_all_paths();
1964     } else {
1965       select_shortest_path();
1966     }
1967   }
1968 }
1969 
1970 // take all nodes from BFS
1971 void PrintBFS::select_all() {
1972   for (int i = 0; i < _worklist.length(); i++) {
1973     const Node* n = _worklist.at(i);
1974     Info* info = find_info(n);
1975     info->set_mark();
1976   }
1977 }
1978 
1979 // traverse backward from target, along edges found in BFS
1980 void PrintBFS::select_all_paths() {
1981   int pos = 0;
1982   GrowableArray<const Node*> backtrace;
1983   // start from target
1984   backtrace.push(_target);
1985   find_info(_target)->set_mark();
1986   // traverse backward
1987   while (pos < backtrace.length()) {
1988     const Node* n = backtrace.at(pos++);
1989     Info* info = find_info(n);
1990     for (int i = 0; i < info->edge_bwd.length(); i++) {
1991       // all backward edges
1992       const Node* back = info->edge_bwd.at(i);
1993       Info* back_info = find_info(back);
1994       if (!back_info->is_marked()) {
1995         // not yet found this on way back.
1996         back_info->set_distance_from_target(info->distance_from_target() + 1);
1997         if (back_info->distance_from_target() + back_info->distance() <= _max_distance) {
1998           // total distance is small enough
1999           back_info->set_mark();
2000           backtrace.push(back);
2001         }
2002       }
2003     }
2004   }
2005 }
2006 
2007 void PrintBFS::select_shortest_path() {
2008   const Node* current = _target;
2009   while (true) {
2010     Info* info = find_info(current);
2011     info->set_mark();
2012     if (current == _start) {
2013       break;
2014     }
2015     // first edge -> leads us one step closer to _start
2016     current = info->edge_bwd.at(0);
2017   }
2018 }
2019 
2020 // go through worklist in desired order, put the marked ones in print list
2021 void PrintBFS::sort() {
2022   if (_traverse_inputs && !_traverse_outputs) {
2023     // reverse order
2024     for (int i = _worklist.length() - 1; i >= 0; i--) {
2025       const Node* n = _worklist.at(i);
2026       Info* info = find_info(n);
2027       if (info->is_marked()) {
2028         _print_list.push(n);
2029       }
2030     }
2031   } else {
2032     // same order as worklist
2033     for (int i = 0; i < _worklist.length(); i++) {
2034       const Node* n = _worklist.at(i);
2035       Info* info = find_info(n);
2036       if (info->is_marked()) {
2037         _print_list.push(n);
2038       }
2039     }
2040   }
2041   if (_sort_idx) {
2042     _print_list.sort(node_idx_cmp);
2043   }
2044 }
2045 
2046 // go through printlist and print
2047 void PrintBFS::print() {
2048   if (_print_list.length() > 0 ) {
2049     print_header();
2050     for (int i = 0; i < _print_list.length(); i++) {
2051       const Node* n = _print_list.at(i);
2052       print_node(n);
2053     }
2054   } else {
2055     _output->print_cr("No nodes to print.");
2056   }
2057 }
2058 
2059 void PrintBFS::print_options_help(bool print_examples) {
2060   _output->print_cr("Usage: node->dump_bfs(int max_distance, Node* target, char* options)");
2061   _output->print_cr("");
2062   _output->print_cr("Use cases:");
2063   _output->print_cr("  BFS traversal: no target required");
2064   _output->print_cr("  shortest path: set target");
2065   _output->print_cr("  all paths: set target and put 'A' in options");
2066   _output->print_cr("  detect loop: subcase of all paths, have start==target");
2067   _output->print_cr("");
2068   _output->print_cr("Arguments:");
2069   _output->print_cr("  this/start: staring point of BFS");
2070   _output->print_cr("  target:");
2071   _output->print_cr("    if null: simple BFS");
2072   _output->print_cr("    else: shortest path or all paths between this/start and target");
2073   _output->print_cr("  options:");
2074   _output->print_cr("    if null: same as \"cdmox@B\"");
2075   _output->print_cr("    else: use combination of following characters");
2076   _output->print_cr("      h: display this help info");
2077   _output->print_cr("      H: display this help info, with examples");
2078   _output->print_cr("      +: traverse in-edges (on if neither + nor -)");
2079   _output->print_cr("      -: traverse out-edges");
2080   _output->print_cr("      c: visit control nodes");
2081   _output->print_cr("      d: visit data nodes");
2082   _output->print_cr("      m: visit memory nodes");
2083   _output->print_cr("      o: visit other nodes");
2084   _output->print_cr("      x: visit mixed nodes");
2085   _output->print_cr("      C: boundary control nodes");
2086   _output->print_cr("      D: boundary data nodes");
2087   _output->print_cr("      M: boundary memory nodes");
2088   _output->print_cr("      O: boundary other nodes");
2089   _output->print_cr("      X: boundary mixed nodes");
2090   _output->print_cr("      #: display node category in color (not supported in all terminals)");
2091   _output->print_cr("      S: sort displayed nodes by node idx");
2092   _output->print_cr("      A: all paths (not just shortest path to target)");
2093   _output->print_cr("      @: print old nodes - before matching (if available)");
2094   _output->print_cr("      B: print scheduling blocks (if available)");
2095   _output->print_cr("      $: dump only, no header, no other columns");
2096   _output->print_cr("");
2097   _output->print_cr("recursively follow edges to nodes with permitted visit types,");
2098   _output->print_cr("on the boundary additionally display nodes allowed in boundary types");
2099   _output->print_cr("Note: the categories can be overlapping. For example a mixed node");
2100   _output->print_cr("      can contain control and memory output. Some from the other");
2101   _output->print_cr("      category are also control (Halt, Return, etc).");
2102   _output->print_cr("");
2103   _output->print_cr("output columns:");
2104   _output->print_cr("  dist:  BFS distance to this/start");
2105   _output->print_cr("  apd:   all paths distance (d_outputart + d_target)");
2106   _output->print_cr("  block: block identifier, based on _pre_order");
2107   _output->print_cr("  head:  first node in block");
2108   _output->print_cr("  idom:  head node of idom block");
2109   _output->print_cr("  depth: depth of block (_dom_depth)");
2110   _output->print_cr("  old:   old IR node - before matching");
2111   _output->print_cr("  dump:  node->dump()");
2112   _output->print_cr("");
2113   _output->print_cr("Note: if none of the \"cmdxo\" characters are in the options string");
2114   _output->print_cr("      then we set all of them.");
2115   _output->print_cr("      This allows for short strings like \"#\" for colored input traversal");
2116   _output->print_cr("      or \"-#\" for colored output traversal.");
2117   if (print_examples) {
2118     _output->print_cr("");
2119     _output->print_cr("Examples:");
2120     _output->print_cr("  if->dump_bfs(10, 0, \"+cxo\")");
2121     _output->print_cr("    starting at some if node, traverse inputs recursively");
2122     _output->print_cr("    only along control (mixed and other can also be control)");
2123     _output->print_cr("  phi->dump_bfs(5, 0, \"-dxo\")");
2124     _output->print_cr("    starting at phi node, traverse outputs recursively");
2125     _output->print_cr("    only along data (mixed and other can also have data flow)");
2126     _output->print_cr("  find_node(385)->dump_bfs(3, 0, \"cdmox+#@B\")");
2127     _output->print_cr("    find inputs of node 385, up to 3 nodes up (+)");
2128     _output->print_cr("    traverse all nodes (cdmox), use colors (#)");
2129     _output->print_cr("    display old nodes and blocks, if they exist");
2130     _output->print_cr("    useful call to start with");
2131     _output->print_cr("  find_node(102)->dump_bfs(10, 0, \"dCDMOX-\")");
2132     _output->print_cr("    find non-data dependencies of a data node");
2133     _output->print_cr("    follow data node outputs until we find another category");
2134     _output->print_cr("    node as the boundary");
2135     _output->print_cr("  x->dump_bfs(10, y, 0)");
2136     _output->print_cr("    find shortest path from x to y, along any edge or node");
2137     _output->print_cr("    will not find a path if it is longer than 10");
2138     _output->print_cr("    useful to find how x and y are related");
2139     _output->print_cr("  find_node(741)->dump_bfs(20, find_node(746), \"c+\")");
2140     _output->print_cr("    find shortest control path between two nodes");
2141     _output->print_cr("  find_node(741)->dump_bfs(8, find_node(746), \"cdmox+A\")");
2142     _output->print_cr("    find all paths (A) between two nodes of length at most 8");
2143     _output->print_cr("  find_node(741)->dump_bfs(7, find_node(741), \"c+A\")");
2144     _output->print_cr("    find all control loops for this node");
2145   }
2146 }
2147 
2148 bool PrintBFS::parse_options() {
2149   if (_options == nullptr) {
2150     _options = "cdmox@B"; // default options
2151   }
2152   size_t len = strlen(_options);
2153   for (size_t i = 0; i < len; i++) {
2154     switch (_options[i]) {
2155       case '+':
2156         _traverse_inputs = true;
2157         break;
2158       case '-':
2159         _traverse_outputs = true;
2160         break;
2161       case 'c':
2162         _filter_visit._control = true;
2163         break;
2164       case 'm':
2165         _filter_visit._memory = true;
2166         break;
2167       case 'd':
2168         _filter_visit._data = true;
2169         break;
2170       case 'x':
2171         _filter_visit._mixed = true;
2172         break;
2173       case 'o':
2174         _filter_visit._other = true;
2175         break;
2176       case 'C':
2177         _filter_boundary._control = true;
2178         break;
2179       case 'M':
2180         _filter_boundary._memory = true;
2181         break;
2182       case 'D':
2183         _filter_boundary._data = true;
2184         break;
2185       case 'X':
2186         _filter_boundary._mixed = true;
2187         break;
2188       case 'O':
2189         _filter_boundary._other = true;
2190         break;
2191       case 'S':
2192         _sort_idx = true;
2193         break;
2194       case 'A':
2195         _all_paths = true;
2196         break;
2197       case '#':
2198         _use_color = true;
2199         break;
2200       case 'B':
2201         _print_blocks = true;
2202         break;
2203       case '@':
2204         _print_old = true;
2205         break;
2206       case '$':
2207         _dump_only = true;
2208         break;
2209       case 'h':
2210         print_options_help(false);
2211         return false;
2212        case 'H':
2213         print_options_help(true);
2214         return false;
2215       default:
2216         _output->print_cr("dump_bfs: Unrecognized option \'%c\'", _options[i]);
2217         _output->print_cr("for help, run: find_node(0)->dump_bfs(0,0,\"H\")");
2218         return false;
2219     }
2220   }
2221   if (!_traverse_inputs && !_traverse_outputs) {
2222     _traverse_inputs = true;
2223   }
2224   if (_filter_visit.is_empty()) {
2225     _filter_visit.set_all();
2226   }
2227   Compile* C = Compile::current();
2228   _print_old &= (C->matcher() != nullptr); // only show old if there are new
2229   _print_blocks &= (C->cfg() != nullptr); // only show blocks if available
2230   return true;
2231 }
2232 
2233 void PrintBFS::DumpConfigColored::pre_dump(outputStream* st, const Node* n) {
2234   if (!_bfs->_use_color) {
2235     return;
2236   }
2237   Info* info = _bfs->find_info(n);
2238   if (info == nullptr || !info->is_marked()) {
2239     return;
2240   }
2241 
2242   const Type* t = n->bottom_type();
2243   switch (t->category()) {
2244     case Type::Category::Data:
2245       st->print("\u001b[34m");
2246       break;
2247     case Type::Category::Memory:
2248       st->print("\u001b[32m");
2249       break;
2250     case Type::Category::Mixed:
2251       st->print("\u001b[35m");
2252       break;
2253     case Type::Category::Control:
2254       st->print("\u001b[31m");
2255       break;
2256     case Type::Category::Other:
2257       st->print("\u001b[33m");
2258       break;
2259     case Type::Category::Undef:
2260       n->dump();
2261       assert(false, "category undef ??");
2262       break;
2263     default:
2264       n->dump();
2265       assert(false, "not covered");
2266       break;
2267   }
2268 }
2269 
2270 void PrintBFS::DumpConfigColored::post_dump(outputStream* st) {
2271   if (!_bfs->_use_color) {
2272     return;
2273   }
2274   st->print("\u001b[0m"); // white
2275 }
2276 
2277 Node* PrintBFS::old_node(const Node* n) {
2278   Compile* C = Compile::current();
2279   if (C->matcher() == nullptr || !C->node_arena()->contains(n)) {
2280     return (Node*)nullptr;
2281   } else {
2282     return C->matcher()->find_old_node(n);
2283   }
2284 }
2285 
2286 void PrintBFS::print_node_idx(const Node* n) {
2287   Compile* C = Compile::current();
2288   char buf[30];
2289   if (n == nullptr) {
2290     os::snprintf_checked(buf, sizeof(buf), "_");           // null
2291   } else if (C->node_arena()->contains(n)) {
2292     os::snprintf_checked(buf, sizeof(buf), "%d", n->_idx);  // new node
2293   } else {
2294     os::snprintf_checked(buf, sizeof(buf), "o%d", n->_idx); // old node
2295   }
2296   _output->print("%6s", buf);
2297 }
2298 
2299 void PrintBFS::print_block_id(const Block* b) {
2300   Compile* C = Compile::current();
2301   char buf[30];
2302   os::snprintf_checked(buf, sizeof(buf), "B%d", b->_pre_order);
2303   _output->print("%7s", buf);
2304 }
2305 
2306 void PrintBFS::print_node_block(const Node* n) {
2307   Compile* C = Compile::current();
2308   Block* b = C->node_arena()->contains(n)
2309              ? C->cfg()->get_block_for_node(n)
2310              : nullptr; // guard against old nodes
2311   if (b == nullptr) {
2312     _output->print("      _"); // Block
2313     _output->print("     _");  // head
2314     _output->print("     _");  // idom
2315     _output->print("      _"); // depth
2316   } else {
2317     print_block_id(b);
2318     print_node_idx(b->head());
2319     if (b->_idom) {
2320       print_node_idx(b->_idom->head());
2321     } else {
2322       _output->print("     _"); // idom
2323     }
2324     _output->print("%6d ", b->_dom_depth);
2325   }
2326 }
2327 
2328 // filter, and add to worklist, add info, note traversal edges
2329 void PrintBFS::maybe_traverse(const Node* src, const Node* dst) {
2330   if (dst != nullptr &&
2331      (_filter_visit.accepts(dst) ||
2332       _filter_boundary.accepts(dst) ||
2333       dst == _start)) { // correct category or start?
2334     if (find_info(dst) == nullptr) {
2335       // never visited - set up info
2336       _worklist.push(dst);
2337       int d = 0;
2338       if (dst != _start) {
2339         d = find_info(src)->distance() + 1;
2340       }
2341       make_info(dst, d);
2342     }
2343     if (src != dst) {
2344       // traversal edges useful during select
2345       find_info(dst)->edge_bwd.push(src);
2346     }
2347   }
2348 }
2349 
2350 void PrintBFS::print_header() const {
2351   if (_dump_only) {
2352     return; // no header in dump only mode
2353   }
2354   _output->print("dist");                         // distance
2355   if (_all_paths) {
2356     _output->print(" apd");                       // all paths distance
2357   }
2358   if (_print_blocks) {
2359     _output->print(" [block  head  idom depth]"); // block
2360   }
2361   if (_print_old) {
2362     _output->print("   old");                     // old node
2363   }
2364   _output->print(" dump\n");                      // node dump
2365   _output->print_cr("---------------------------------------------");
2366 }
2367 
2368 void PrintBFS::print_node(const Node* n) {
2369   if (_dump_only) {
2370     n->dump("\n", false, _output, &_dcc);
2371     return;
2372   }
2373   _output->print("%4d", find_info(n)->distance());// distance
2374   if (_all_paths) {
2375     Info* info = find_info(n);
2376     int apd = info->distance() + info->distance_from_target();
2377     _output->print("%4d", apd);                   // all paths distance
2378   }
2379   if (_print_blocks) {
2380     print_node_block(n);                          // block
2381   }
2382   if (_print_old) {
2383     print_node_idx(old_node(n));                  // old node
2384   }
2385   _output->print(" ");
2386   n->dump("\n", false, _output, &_dcc);           // node dump
2387 }
2388 
2389 //------------------------------dump_bfs--------------------------------------
2390 // Call this from debugger
2391 // Useful for BFS traversal, shortest path, all path, loop detection, etc
2392 // Designed to be more readable, and provide additional info
2393 // To find all options, run:
2394 //   find_node(0)->dump_bfs(0,0,"H")
2395 void Node::dump_bfs(const int max_distance, Node* target, const char* options) const {
2396   dump_bfs(max_distance, target, options, tty);
2397 }
2398 
2399 // Used to dump to stream.
2400 void Node::dump_bfs(const int max_distance, Node* target, const char* options, outputStream* st) const {
2401   PrintBFS bfs(this, max_distance, target, options, st);
2402   bfs.run();
2403 }
2404 
2405 // Call this from debugger, with default arguments
2406 void Node::dump_bfs(const int max_distance) const {
2407   dump_bfs(max_distance, nullptr, nullptr);
2408 }
2409 
2410 // -----------------------------dump_idx---------------------------------------
2411 void Node::dump_idx(bool align, outputStream* st, DumpConfig* dc) const {
2412   if (dc != nullptr) {
2413     dc->pre_dump(st, this);
2414   }
2415   Compile* C = Compile::current();
2416   bool is_new = C->node_arena()->contains(this);
2417   if (align) { // print prefix empty spaces$
2418     // +1 for leading digit, +1 for "o"
2419     uint max_width = static_cast<uint>(log10(static_cast<double>(C->unique()))) + 2;
2420     // +1 for leading digit, maybe +1 for "o"
2421     uint width = static_cast<uint>(log10(static_cast<double>(_idx))) + 1 + (is_new ? 0 : 1);
2422     while (max_width > width) {
2423       st->print(" ");
2424       width++;
2425     }
2426   }
2427   if (!is_new) {
2428     st->print("o");
2429   }
2430   st->print("%d", _idx);
2431   if (dc != nullptr) {
2432     dc->post_dump(st);
2433   }
2434 }
2435 
2436 // -----------------------------dump_name--------------------------------------
2437 void Node::dump_name(outputStream* st, DumpConfig* dc) const {
2438   if (dc != nullptr) {
2439     dc->pre_dump(st, this);
2440   }
2441   st->print("%s", Name());
2442   if (dc != nullptr) {
2443     dc->post_dump(st);
2444   }
2445 }
2446 
2447 // -----------------------------Name-------------------------------------------
2448 extern const char *NodeClassNames[];
2449 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
2450 
2451 static bool is_disconnected(const Node* n) {
2452   for (uint i = 0; i < n->req(); i++) {
2453     if (n->in(i) != nullptr)  return false;
2454   }
2455   return true;
2456 }
2457 
2458 #ifdef ASSERT
2459 void Node::dump_orig(outputStream *st, bool print_key) const {
2460   Compile* C = Compile::current();
2461   Node* orig = _debug_orig;
2462   if (not_a_node(orig)) orig = nullptr;
2463   if (orig != nullptr && !C->node_arena()->contains(orig)) orig = nullptr;
2464   if (orig == nullptr) return;
2465   if (print_key) {
2466     st->print(" !orig=");
2467   }
2468   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
2469   if (not_a_node(fast)) fast = nullptr;
2470   while (orig != nullptr) {
2471     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
2472     if (discon) st->print("[");
2473     if (!Compile::current()->node_arena()->contains(orig))
2474       st->print("o");
2475     st->print("%d", orig->_idx);
2476     if (discon) st->print("]");
2477     orig = orig->debug_orig();
2478     if (not_a_node(orig)) orig = nullptr;
2479     if (orig != nullptr && !C->node_arena()->contains(orig)) orig = nullptr;
2480     if (orig != nullptr) st->print(",");
2481     if (fast != nullptr) {
2482       // Step fast twice for each single step of orig:
2483       fast = fast->debug_orig();
2484       if (not_a_node(fast)) fast = nullptr;
2485       if (fast != nullptr && fast != orig) {
2486         fast = fast->debug_orig();
2487         if (not_a_node(fast)) fast = nullptr;
2488       }
2489       if (fast == orig) {
2490         st->print("...");
2491         break;
2492       }
2493     }
2494   }
2495 }
2496 
2497 void Node::set_debug_orig(Node* orig) {
2498   _debug_orig = orig;
2499   if (BreakAtNode == 0)  return;
2500   if (not_a_node(orig))  orig = nullptr;
2501   int trip = 10;
2502   while (orig != nullptr) {
2503     if (orig->debug_idx() == BreakAtNode || (uintx)orig->_idx == BreakAtNode) {
2504       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=" UINT64_FORMAT " orig._idx=%d orig._debug_idx=" UINT64_FORMAT,
2505                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
2506       BREAKPOINT;
2507     }
2508     orig = orig->debug_orig();
2509     if (not_a_node(orig))  orig = nullptr;
2510     if (trip-- <= 0)  break;
2511   }
2512 }
2513 #endif //ASSERT
2514 
2515 //------------------------------dump------------------------------------------
2516 // Dump a Node
2517 void Node::dump(const char* suffix, bool mark, outputStream* st, DumpConfig* dc) const {
2518   Compile* C = Compile::current();
2519   bool is_new = C->node_arena()->contains(this);
2520   C->_in_dump_cnt++;
2521 
2522   // idx mark name ===
2523   dump_idx(true, st, dc);
2524   st->print(mark ? " >" : "  ");
2525   dump_name(st, dc);
2526   st->print("  === ");
2527 
2528   // Dump the required and precedence inputs
2529   dump_req(st, dc);
2530   dump_prec(st, dc);
2531   // Dump the outputs
2532   dump_out(st, dc);
2533 
2534   if (is_disconnected(this)) {
2535 #ifdef ASSERT
2536     st->print("  [" UINT64_FORMAT "]", debug_idx());
2537     dump_orig(st);
2538 #endif
2539     st->cr();
2540     C->_in_dump_cnt--;
2541     return;                     // don't process dead nodes
2542   }
2543 
2544   if (C->clone_map().value(_idx) != 0) {
2545     C->clone_map().dump(_idx, st);
2546   }
2547   // Dump node-specific info
2548   dump_spec(st);
2549 #ifdef ASSERT
2550   // Dump the non-reset _debug_idx
2551   if (Verbose && WizardMode) {
2552     st->print("  [" UINT64_FORMAT "]", debug_idx());
2553   }
2554 #endif
2555 
2556   const Type *t = bottom_type();
2557 
2558   if (t != nullptr && (t->isa_instptr() || t->isa_instklassptr())) {
2559     const TypeInstPtr  *toop = t->isa_instptr();
2560     const TypeInstKlassPtr *tkls = t->isa_instklassptr();
2561     if (toop) {
2562       st->print("  Oop:");
2563     } else if (tkls) {
2564       st->print("  Klass:");
2565     }
2566     t->dump_on(st);
2567   } else if (t == Type::MEMORY) {
2568     st->print("  Memory:");
2569     MemNode::dump_adr_type(this, adr_type(), st);
2570   } else if (Verbose || WizardMode) {
2571     st->print("  Type:");
2572     if (t) {
2573       t->dump_on(st);
2574     } else {
2575       st->print("no type");
2576     }
2577   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
2578     // Dump MachSpillcopy vector type.
2579     t->dump_on(st);
2580   }
2581   if (is_new) {
2582     DEBUG_ONLY(dump_orig(st));
2583     Node_Notes* nn = C->node_notes_at(_idx);
2584     if (nn != nullptr && !nn->is_clear()) {
2585       if (nn->jvms() != nullptr) {
2586         st->print(" !jvms:");
2587         nn->jvms()->dump_spec(st);
2588       }
2589     }
2590   }
2591   if (suffix) st->print("%s", suffix);
2592   C->_in_dump_cnt--;
2593 }
2594 
2595 // call from debugger: dump node to tty with newline
2596 void Node::dump() const {
2597   dump("\n");
2598 }
2599 
2600 //------------------------------dump_req--------------------------------------
2601 void Node::dump_req(outputStream* st, DumpConfig* dc) const {
2602   // Dump the required input edges
2603   for (uint i = 0; i < req(); i++) {    // For all required inputs
2604     Node* d = in(i);
2605     if (d == nullptr) {
2606       st->print("_ ");
2607     } else if (not_a_node(d)) {
2608       st->print("not_a_node ");  // uninitialized, sentinel, garbage, etc.
2609     } else {
2610       d->dump_idx(false, st, dc);
2611       st->print(" ");
2612     }
2613   }
2614 }
2615 
2616 
2617 //------------------------------dump_prec-------------------------------------
2618 void Node::dump_prec(outputStream* st, DumpConfig* dc) const {
2619   // Dump the precedence edges
2620   int any_prec = 0;
2621   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
2622     Node* p = in(i);
2623     if (p != nullptr) {
2624       if (!any_prec++) st->print(" |");
2625       if (not_a_node(p)) { st->print("not_a_node "); continue; }
2626       p->dump_idx(false, st, dc);
2627       st->print(" ");
2628     }
2629   }
2630 }
2631 
2632 //------------------------------dump_out--------------------------------------
2633 void Node::dump_out(outputStream* st, DumpConfig* dc) const {
2634   // Delimit the output edges
2635   st->print(" [[ ");
2636   // Dump the output edges
2637   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
2638     Node* u = _out[i];
2639     if (u == nullptr) {
2640       st->print("_ ");
2641     } else if (not_a_node(u)) {
2642       st->print("not_a_node ");
2643     } else {
2644       u->dump_idx(false, st, dc);
2645       st->print(" ");
2646     }
2647   }
2648   st->print("]] ");
2649 }
2650 
2651 //------------------------------dump-------------------------------------------
2652 // call from debugger: dump Node's inputs (or outputs if d negative)
2653 void Node::dump(int d) const {
2654   dump_bfs(abs(d), nullptr, (d > 0) ? "+$" : "-$");
2655 }
2656 
2657 //------------------------------dump_ctrl--------------------------------------
2658 // call from debugger: dump Node's control inputs (or outputs if d negative)
2659 void Node::dump_ctrl(int d) const {
2660   dump_bfs(abs(d), nullptr, (d > 0) ? "+$c" : "-$c");
2661 }
2662 
2663 //-----------------------------dump_compact------------------------------------
2664 void Node::dump_comp() const {
2665   this->dump_comp("\n");
2666 }
2667 
2668 //-----------------------------dump_compact------------------------------------
2669 // Dump a Node in compact representation, i.e., just print its name and index.
2670 // Nodes can specify additional specifics to print in compact representation by
2671 // implementing dump_compact_spec.
2672 void Node::dump_comp(const char* suffix, outputStream *st) const {
2673   Compile* C = Compile::current();
2674   C->_in_dump_cnt++;
2675   st->print("%s(%d)", Name(), _idx);
2676   this->dump_compact_spec(st);
2677   if (suffix) {
2678     st->print("%s", suffix);
2679   }
2680   C->_in_dump_cnt--;
2681 }
2682 
2683 // VERIFICATION CODE
2684 // Verify all nodes if verify_depth is negative
2685 void Node::verify(int verify_depth, VectorSet& visited, Node_List& worklist) {
2686   assert(verify_depth != 0, "depth should not be 0");
2687   Compile* C = Compile::current();
2688   uint last_index_on_current_depth = worklist.size() - 1;
2689   verify_depth--; // Visiting the first node on depth 1
2690   // Only add nodes to worklist if verify_depth is negative (visit all nodes) or greater than 0
2691   bool add_to_worklist = verify_depth != 0;
2692 
2693   for (uint list_index = 0; list_index < worklist.size(); list_index++) {
2694     Node* n = worklist[list_index];
2695 
2696     if (n->is_Con() && n->bottom_type() == Type::TOP) {
2697       if (C->cached_top_node() == nullptr) {
2698         C->set_cached_top_node((Node*)n);
2699       }
2700       assert(C->cached_top_node() == n, "TOP node must be unique");
2701     }
2702 
2703     uint in_len = n->len();
2704     for (uint i = 0; i < in_len; i++) {
2705       Node* x = n->_in[i];
2706       if (!x || x->is_top()) {
2707         continue;
2708       }
2709 
2710       // Verify my input has a def-use edge to me
2711       // Count use-def edges from n to x
2712       int cnt = 1;
2713       for (uint j = 0; j < i; j++) {
2714         if (n->_in[j] == x) {
2715           cnt++;
2716           break;
2717         }
2718       }
2719       if (cnt == 2) {
2720         // x is already checked as n's previous input, skip its duplicated def-use count checking
2721         continue;
2722       }
2723       for (uint j = i + 1; j < in_len; j++) {
2724         if (n->_in[j] == x) {
2725           cnt++;
2726         }
2727       }
2728 
2729       // Count def-use edges from x to n
2730       uint max = x->_outcnt;
2731       for (uint k = 0; k < max; k++) {
2732         if (x->_out[k] == n) {
2733           cnt--;
2734         }
2735       }
2736       assert(cnt == 0, "mismatched def-use edge counts");
2737 
2738       if (add_to_worklist && !visited.test_set(x->_idx)) {
2739         worklist.push(x);
2740       }
2741     }
2742 
2743     if (verify_depth > 0 && list_index == last_index_on_current_depth) {
2744       // All nodes on this depth were processed and its inputs are on the worklist. Decrement verify_depth and
2745       // store the current last list index which is the last node in the list with the new depth. All nodes
2746       // added afterwards will have a new depth again. Stop adding new nodes if depth limit is reached (=0).
2747       verify_depth--;
2748       if (verify_depth == 0) {
2749         add_to_worklist = false;
2750       }
2751       last_index_on_current_depth = worklist.size() - 1;
2752     }
2753   }
2754 }
2755 #endif // not PRODUCT
2756 
2757 //------------------------------Registers--------------------------------------
2758 // Do we Match on this edge index or not?  Generally false for Control
2759 // and true for everything else.  Weird for calls & returns.
2760 uint Node::match_edge(uint idx) const {
2761   return idx;                   // True for other than index 0 (control)
2762 }
2763 
2764 // Register classes are defined for specific machines
2765 const RegMask &Node::out_RegMask() const {
2766   ShouldNotCallThis();
2767   return RegMask::Empty;
2768 }
2769 
2770 const RegMask &Node::in_RegMask(uint) const {
2771   ShouldNotCallThis();
2772   return RegMask::Empty;
2773 }
2774 
2775 void Node_Array::grow(uint i) {
2776   assert(_max > 0, "invariant");
2777   uint old = _max;
2778   _max = next_power_of_2(i);
2779   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2780   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2781 }
2782 
2783 void Node_Array::insert(uint i, Node* n) {
2784   if (_nodes[_max - 1]) {
2785     grow(_max);
2786   }
2787   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i + 1], ((_max - i - 1) * sizeof(Node*)));
2788   _nodes[i] = n;
2789 }
2790 
2791 void Node_Array::remove(uint i) {
2792   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i + 1], (HeapWord*)&_nodes[i], ((_max - i - 1) * sizeof(Node*)));
2793   _nodes[_max - 1] = nullptr;
2794 }
2795 
2796 void Node_Array::dump() const {
2797 #ifndef PRODUCT
2798   for (uint i = 0; i < _max; i++) {
2799     Node* nn = _nodes[i];
2800     if (nn != nullptr) {
2801       tty->print("%5d--> ",i); nn->dump();
2802     }
2803   }
2804 #endif
2805 }
2806 
2807 //--------------------------is_iteratively_computed------------------------------
2808 // Operation appears to be iteratively computed (such as an induction variable)
2809 // It is possible for this operation to return false for a loop-varying
2810 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2811 bool Node::is_iteratively_computed() {
2812   if (ideal_reg()) { // does operation have a result register?
2813     for (uint i = 1; i < req(); i++) {
2814       Node* n = in(i);
2815       if (n != nullptr && n->is_Phi()) {
2816         for (uint j = 1; j < n->req(); j++) {
2817           if (n->in(j) == this) {
2818             return true;
2819           }
2820         }
2821       }
2822     }
2823   }
2824   return false;
2825 }
2826 
2827 //--------------------------find_similar------------------------------
2828 // Return a node with opcode "opc" and same inputs as "this" if one can
2829 // be found; Otherwise return null;
2830 Node* Node::find_similar(int opc) {
2831   if (req() >= 2) {
2832     Node* def = in(1);
2833     if (def && def->outcnt() >= 2) {
2834       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2835         Node* use = def->fast_out(i);
2836         if (use != this &&
2837             use->Opcode() == opc &&
2838             use->req() == req()) {
2839           uint j;
2840           for (j = 0; j < use->req(); j++) {
2841             if (use->in(j) != in(j)) {
2842               break;
2843             }
2844           }
2845           if (j == use->req()) {
2846             return use;
2847           }
2848         }
2849       }
2850     }
2851   }
2852   return nullptr;
2853 }
2854 
2855 
2856 //--------------------------unique_ctrl_out_or_null-------------------------
2857 // Return the unique control out if only one. Null if none or more than one.
2858 Node* Node::unique_ctrl_out_or_null() const {
2859   Node* found = nullptr;
2860   for (uint i = 0; i < outcnt(); i++) {
2861     Node* use = raw_out(i);
2862     if (use->is_CFG() && use != this) {
2863       if (found != nullptr) {
2864         return nullptr;
2865       }
2866       found = use;
2867     }
2868   }
2869   return found;
2870 }
2871 
2872 //--------------------------unique_ctrl_out------------------------------
2873 // Return the unique control out. Asserts if none or more than one control out.
2874 Node* Node::unique_ctrl_out() const {
2875   Node* ctrl = unique_ctrl_out_or_null();
2876   assert(ctrl != nullptr, "control out is assumed to be unique");
2877   return ctrl;
2878 }
2879 
2880 void Node::ensure_control_or_add_prec(Node* c) {
2881   if (in(0) == nullptr) {
2882     set_req(0, c);
2883   } else if (in(0) != c) {
2884     add_prec(c);
2885   }
2886 }
2887 
2888 bool Node::is_dead_loop_safe() const {
2889   if (is_Phi()) {
2890     return true;
2891   }
2892   if (is_Proj() && in(0) == nullptr)  {
2893     return true;
2894   }
2895   if ((_flags & (Flag_is_dead_loop_safe | Flag_is_Con)) != 0) {
2896     if (!is_Proj()) {
2897       return true;
2898     }
2899     if (in(0)->is_Allocate()) {
2900       return false;
2901     }
2902     // MemNode::can_see_stored_value() peeks through the boxing call
2903     if (in(0)->is_CallStaticJava() && in(0)->as_CallStaticJava()->is_boxing_method()) {
2904       return false;
2905     }
2906     return true;
2907   }
2908   return false;
2909 }
2910 
2911 //=============================================================================
2912 //------------------------------yank-------------------------------------------
2913 // Find and remove
2914 void Node_List::yank( Node *n ) {
2915   uint i;
2916   for (i = 0; i < _cnt; i++) {
2917     if (_nodes[i] == n) {
2918       break;
2919     }
2920   }
2921 
2922   if (i < _cnt) {
2923     _nodes[i] = _nodes[--_cnt];
2924   }
2925 }
2926 
2927 //------------------------------dump-------------------------------------------
2928 void Node_List::dump() const {
2929 #ifndef PRODUCT
2930   for (uint i = 0; i < _cnt; i++) {
2931     if (_nodes[i]) {
2932       tty->print("%5d--> ", i);
2933       _nodes[i]->dump();
2934     }
2935   }
2936 #endif
2937 }
2938 
2939 void Node_List::dump_simple() const {
2940 #ifndef PRODUCT
2941   for (uint i = 0; i < _cnt; i++) {
2942     if( _nodes[i] ) {
2943       tty->print(" %d", _nodes[i]->_idx);
2944     } else {
2945       tty->print(" null");
2946     }
2947   }
2948 #endif
2949 }
2950 
2951 //=============================================================================
2952 //------------------------------remove-----------------------------------------
2953 void Unique_Node_List::remove(Node* n) {
2954   if (_in_worklist.test(n->_idx)) {
2955     for (uint i = 0; i < size(); i++) {
2956       if (_nodes[i] == n) {
2957         map(i, Node_List::pop());
2958         _in_worklist.remove(n->_idx);
2959         return;
2960       }
2961     }
2962     ShouldNotReachHere();
2963   }
2964 }
2965 
2966 //-----------------------remove_useless_nodes----------------------------------
2967 // Remove useless nodes from worklist
2968 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2969   for (uint i = 0; i < size(); ++i) {
2970     Node *n = at(i);
2971     assert( n != nullptr, "Did not expect null entries in worklist");
2972     if (!useful.test(n->_idx)) {
2973       _in_worklist.remove(n->_idx);
2974       map(i, Node_List::pop());
2975       --i;  // Visit popped node
2976       // If it was last entry, loop terminates since size() was also reduced
2977     }
2978   }
2979 }
2980 
2981 //=============================================================================
2982 void Node_Stack::grow() {
2983   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2984   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2985   size_t max = old_max << 1;             // max * 2
2986   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2987   _inode_max = _inodes + max;
2988   _inode_top = _inodes + old_top;        // restore _top
2989 }
2990 
2991 // Node_Stack is used to map nodes.
2992 Node* Node_Stack::find(uint idx) const {
2993   uint sz = size();
2994   for (uint i = 0; i < sz; i++) {
2995     if (idx == index_at(i)) {
2996       return node_at(i);
2997     }
2998   }
2999   return nullptr;
3000 }
3001 
3002 //=============================================================================
3003 uint TypeNode::size_of() const { return sizeof(*this); }
3004 #ifndef PRODUCT
3005 void TypeNode::dump_spec(outputStream *st) const {
3006   if (!Verbose && !WizardMode) {
3007     // standard dump does this in Verbose and WizardMode
3008     st->print(" #"); _type->dump_on(st);
3009   }
3010 }
3011 
3012 void TypeNode::dump_compact_spec(outputStream *st) const {
3013   st->print("#");
3014   _type->dump_on(st);
3015 }
3016 #endif
3017 uint TypeNode::hash() const {
3018   return Node::hash() + _type->hash();
3019 }
3020 bool TypeNode::cmp(const Node& n) const {
3021   return !Type::cmp(_type, ((TypeNode&)n)._type);
3022 }
3023 const Type* TypeNode::bottom_type() const { return _type; }
3024 const Type* TypeNode::Value(PhaseGVN* phase) const { return _type; }
3025 
3026 //------------------------------ideal_reg--------------------------------------
3027 uint TypeNode::ideal_reg() const {
3028   return _type->ideal_reg();
3029 }
--- EOF ---