1 /*
   2  * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/barrierSet.hpp"
  27 #include "gc/shared/c2/barrierSetC2.hpp"
  28 #include "libadt/vectset.hpp"
  29 #include "memory/allocation.inline.hpp"
  30 #include "memory/resourceArea.hpp"
  31 #include "opto/ad.hpp"
  32 #include "opto/callGenerator.hpp"
  33 #include "opto/castnode.hpp"
  34 #include "opto/cfgnode.hpp"
  35 #include "opto/connode.hpp"
  36 #include "opto/loopnode.hpp"
  37 #include "opto/machnode.hpp"
  38 #include "opto/matcher.hpp"
  39 #include "opto/node.hpp"
  40 #include "opto/opcodes.hpp"
  41 #include "opto/regmask.hpp"
  42 #include "opto/rootnode.hpp"
  43 #include "opto/type.hpp"
  44 #include "utilities/copy.hpp"
  45 #include "utilities/macros.hpp"
  46 #include "utilities/powerOfTwo.hpp"
  47 #include "utilities/stringUtils.hpp"
  48 
  49 class RegMask;
  50 // #include "phase.hpp"
  51 class PhaseTransform;
  52 class PhaseGVN;
  53 
  54 // Arena we are currently building Nodes in
  55 const uint Node::NotAMachineReg = 0xffff0000;
  56 
  57 #ifndef PRODUCT
  58 extern int nodes_created;
  59 #endif
  60 #ifdef __clang__
  61 #pragma clang diagnostic push
  62 #pragma GCC diagnostic ignored "-Wuninitialized"
  63 #endif
  64 
  65 #ifdef ASSERT
  66 
  67 //-------------------------- construct_node------------------------------------
  68 // Set a breakpoint here to identify where a particular node index is built.
  69 void Node::verify_construction() {
  70   _debug_orig = NULL;
  71   int old_debug_idx = Compile::debug_idx();
  72   int new_debug_idx = old_debug_idx + 1;
  73   if (new_debug_idx > 0) {
  74     // Arrange that the lowest five decimal digits of _debug_idx
  75     // will repeat those of _idx. In case this is somehow pathological,
  76     // we continue to assign negative numbers (!) consecutively.
  77     const int mod = 100000;
  78     int bump = (int)(_idx - new_debug_idx) % mod;
  79     if (bump < 0) {
  80       bump += mod;
  81     }
  82     assert(bump >= 0 && bump < mod, "");
  83     new_debug_idx += bump;
  84   }
  85   Compile::set_debug_idx(new_debug_idx);
  86   set_debug_idx(new_debug_idx);
  87   Compile* C = Compile::current();
  88   assert(C->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  89   if (!C->phase_optimize_finished()) {
  90     // Only check assert during parsing and optimization phase. Skip it while generating code.
  91     assert(C->live_nodes() <= C->max_node_limit(), "Live Node limit exceeded limit");
  92   }
  93   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (int)_idx == BreakAtNode)) {
  94     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d", _idx, _debug_idx);
  95     BREAKPOINT;
  96   }
  97 #if OPTO_DU_ITERATOR_ASSERT
  98   _last_del = NULL;
  99   _del_tick = 0;
 100 #endif
 101   _hash_lock = 0;
 102 }
 103 
 104 
 105 // #ifdef ASSERT ...
 106 
 107 #if OPTO_DU_ITERATOR_ASSERT
 108 void DUIterator_Common::sample(const Node* node) {
 109   _vdui     = VerifyDUIterators;
 110   _node     = node;
 111   _outcnt   = node->_outcnt;
 112   _del_tick = node->_del_tick;
 113   _last     = NULL;
 114 }
 115 
 116 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
 117   assert(_node     == node, "consistent iterator source");
 118   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
 119 }
 120 
 121 void DUIterator_Common::verify_resync() {
 122   // Ensure that the loop body has just deleted the last guy produced.
 123   const Node* node = _node;
 124   // Ensure that at least one copy of the last-seen edge was deleted.
 125   // Note:  It is OK to delete multiple copies of the last-seen edge.
 126   // Unfortunately, we have no way to verify that all the deletions delete
 127   // that same edge.  On this point we must use the Honor System.
 128   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 129   assert(node->_last_del == _last, "must have deleted the edge just produced");
 130   // We liked this deletion, so accept the resulting outcnt and tick.
 131   _outcnt   = node->_outcnt;
 132   _del_tick = node->_del_tick;
 133 }
 134 
 135 void DUIterator_Common::reset(const DUIterator_Common& that) {
 136   if (this == &that)  return;  // ignore assignment to self
 137   if (!_vdui) {
 138     // We need to initialize everything, overwriting garbage values.
 139     _last = that._last;
 140     _vdui = that._vdui;
 141   }
 142   // Note:  It is legal (though odd) for an iterator over some node x
 143   // to be reassigned to iterate over another node y.  Some doubly-nested
 144   // progress loops depend on being able to do this.
 145   const Node* node = that._node;
 146   // Re-initialize everything, except _last.
 147   _node     = node;
 148   _outcnt   = node->_outcnt;
 149   _del_tick = node->_del_tick;
 150 }
 151 
 152 void DUIterator::sample(const Node* node) {
 153   DUIterator_Common::sample(node);      // Initialize the assertion data.
 154   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 155 }
 156 
 157 void DUIterator::verify(const Node* node, bool at_end_ok) {
 158   DUIterator_Common::verify(node, at_end_ok);
 159   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 160 }
 161 
 162 void DUIterator::verify_increment() {
 163   if (_refresh_tick & 1) {
 164     // We have refreshed the index during this loop.
 165     // Fix up _idx to meet asserts.
 166     if (_idx > _outcnt)  _idx = _outcnt;
 167   }
 168   verify(_node, true);
 169 }
 170 
 171 void DUIterator::verify_resync() {
 172   // Note:  We do not assert on _outcnt, because insertions are OK here.
 173   DUIterator_Common::verify_resync();
 174   // Make sure we are still in sync, possibly with no more out-edges:
 175   verify(_node, true);
 176 }
 177 
 178 void DUIterator::reset(const DUIterator& that) {
 179   if (this == &that)  return;  // self assignment is always a no-op
 180   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 181   assert(that._idx          == 0, "assign only the result of Node::outs()");
 182   assert(_idx               == that._idx, "already assigned _idx");
 183   if (!_vdui) {
 184     // We need to initialize everything, overwriting garbage values.
 185     sample(that._node);
 186   } else {
 187     DUIterator_Common::reset(that);
 188     if (_refresh_tick & 1) {
 189       _refresh_tick++;                  // Clear the "was refreshed" flag.
 190     }
 191     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 192   }
 193 }
 194 
 195 void DUIterator::refresh() {
 196   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 197   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 198 }
 199 
 200 void DUIterator::verify_finish() {
 201   // If the loop has killed the node, do not require it to re-run.
 202   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 203   // If this assert triggers, it means that a loop used refresh_out_pos
 204   // to re-synch an iteration index, but the loop did not correctly
 205   // re-run itself, using a "while (progress)" construct.
 206   // This iterator enforces the rule that you must keep trying the loop
 207   // until it "runs clean" without any need for refreshing.
 208   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 209 }
 210 
 211 
 212 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 213   DUIterator_Common::verify(node, at_end_ok);
 214   Node** out    = node->_out;
 215   uint   cnt    = node->_outcnt;
 216   assert(cnt == _outcnt, "no insertions allowed");
 217   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 218   // This last check is carefully designed to work for NO_OUT_ARRAY.
 219 }
 220 
 221 void DUIterator_Fast::verify_limit() {
 222   const Node* node = _node;
 223   verify(node, true);
 224   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 225 }
 226 
 227 void DUIterator_Fast::verify_resync() {
 228   const Node* node = _node;
 229   if (_outp == node->_out + _outcnt) {
 230     // Note that the limit imax, not the pointer i, gets updated with the
 231     // exact count of deletions.  (For the pointer it's always "--i".)
 232     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 233     // This is a limit pointer, with a name like "imax".
 234     // Fudge the _last field so that the common assert will be happy.
 235     _last = (Node*) node->_last_del;
 236     DUIterator_Common::verify_resync();
 237   } else {
 238     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 239     // A normal internal pointer.
 240     DUIterator_Common::verify_resync();
 241     // Make sure we are still in sync, possibly with no more out-edges:
 242     verify(node, true);
 243   }
 244 }
 245 
 246 void DUIterator_Fast::verify_relimit(uint n) {
 247   const Node* node = _node;
 248   assert((int)n > 0, "use imax -= n only with a positive count");
 249   // This must be a limit pointer, with a name like "imax".
 250   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 251   // The reported number of deletions must match what the node saw.
 252   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 253   // Fudge the _last field so that the common assert will be happy.
 254   _last = (Node*) node->_last_del;
 255   DUIterator_Common::verify_resync();
 256 }
 257 
 258 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 259   assert(_outp              == that._outp, "already assigned _outp");
 260   DUIterator_Common::reset(that);
 261 }
 262 
 263 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 264   // at_end_ok means the _outp is allowed to underflow by 1
 265   _outp += at_end_ok;
 266   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 267   _outp -= at_end_ok;
 268   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 269 }
 270 
 271 void DUIterator_Last::verify_limit() {
 272   // Do not require the limit address to be resynched.
 273   //verify(node, true);
 274   assert(_outp == _node->_out, "limit still correct");
 275 }
 276 
 277 void DUIterator_Last::verify_step(uint num_edges) {
 278   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 279   _outcnt   -= num_edges;
 280   _del_tick += num_edges;
 281   // Make sure we are still in sync, possibly with no more out-edges:
 282   const Node* node = _node;
 283   verify(node, true);
 284   assert(node->_last_del == _last, "must have deleted the edge just produced");
 285 }
 286 
 287 #endif //OPTO_DU_ITERATOR_ASSERT
 288 
 289 
 290 #endif //ASSERT
 291 
 292 
 293 // This constant used to initialize _out may be any non-null value.
 294 // The value NULL is reserved for the top node only.
 295 #define NO_OUT_ARRAY ((Node**)-1)
 296 
 297 // Out-of-line code from node constructors.
 298 // Executed only when extra debug info. is being passed around.
 299 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 300   C->set_node_notes_at(idx, nn);
 301 }
 302 
 303 // Shared initialization code.
 304 inline int Node::Init(int req) {
 305   Compile* C = Compile::current();
 306   int idx = C->next_unique();
 307   NOT_PRODUCT(_igv_idx = C->next_igv_idx());
 308 
 309   // Allocate memory for the necessary number of edges.
 310   if (req > 0) {
 311     // Allocate space for _in array to have double alignment.
 312     _in = (Node **) ((char *) (C->node_arena()->AmallocWords(req * sizeof(void*))));
 313   }
 314   // If there are default notes floating around, capture them:
 315   Node_Notes* nn = C->default_node_notes();
 316   if (nn != NULL)  init_node_notes(C, idx, nn);
 317 
 318   // Note:  At this point, C is dead,
 319   // and we begin to initialize the new Node.
 320 
 321   _cnt = _max = req;
 322   _outcnt = _outmax = 0;
 323   _class_id = Class_Node;
 324   _flags = 0;
 325   _out = NO_OUT_ARRAY;
 326   return idx;
 327 }
 328 
 329 //------------------------------Node-------------------------------------------
 330 // Create a Node, with a given number of required edges.
 331 Node::Node(uint req)
 332   : _idx(Init(req))
 333 #ifdef ASSERT
 334   , _parse_idx(_idx)
 335 #endif
 336 {
 337   assert( req < Compile::current()->max_node_limit() - NodeLimitFudgeFactor, "Input limit exceeded" );
 338   debug_only( verify_construction() );
 339   NOT_PRODUCT(nodes_created++);
 340   if (req == 0) {
 341     _in = NULL;
 342   } else {
 343     Node** to = _in;
 344     for(uint i = 0; i < req; i++) {
 345       to[i] = NULL;
 346     }
 347   }
 348 }
 349 
 350 //------------------------------Node-------------------------------------------
 351 Node::Node(Node *n0)
 352   : _idx(Init(1))
 353 #ifdef ASSERT
 354   , _parse_idx(_idx)
 355 #endif
 356 {
 357   debug_only( verify_construction() );
 358   NOT_PRODUCT(nodes_created++);
 359   assert( is_not_dead(n0), "can not use dead node");
 360   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 361 }
 362 
 363 //------------------------------Node-------------------------------------------
 364 Node::Node(Node *n0, Node *n1)
 365   : _idx(Init(2))
 366 #ifdef ASSERT
 367   , _parse_idx(_idx)
 368 #endif
 369 {
 370   debug_only( verify_construction() );
 371   NOT_PRODUCT(nodes_created++);
 372   assert( is_not_dead(n0), "can not use dead node");
 373   assert( is_not_dead(n1), "can not use dead node");
 374   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 375   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 376 }
 377 
 378 //------------------------------Node-------------------------------------------
 379 Node::Node(Node *n0, Node *n1, Node *n2)
 380   : _idx(Init(3))
 381 #ifdef ASSERT
 382   , _parse_idx(_idx)
 383 #endif
 384 {
 385   debug_only( verify_construction() );
 386   NOT_PRODUCT(nodes_created++);
 387   assert( is_not_dead(n0), "can not use dead node");
 388   assert( is_not_dead(n1), "can not use dead node");
 389   assert( is_not_dead(n2), "can not use dead node");
 390   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 391   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 392   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 393 }
 394 
 395 //------------------------------Node-------------------------------------------
 396 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 397   : _idx(Init(4))
 398 #ifdef ASSERT
 399   , _parse_idx(_idx)
 400 #endif
 401 {
 402   debug_only( verify_construction() );
 403   NOT_PRODUCT(nodes_created++);
 404   assert( is_not_dead(n0), "can not use dead node");
 405   assert( is_not_dead(n1), "can not use dead node");
 406   assert( is_not_dead(n2), "can not use dead node");
 407   assert( is_not_dead(n3), "can not use dead node");
 408   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 409   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 410   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 411   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 412 }
 413 
 414 //------------------------------Node-------------------------------------------
 415 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 416   : _idx(Init(5))
 417 #ifdef ASSERT
 418   , _parse_idx(_idx)
 419 #endif
 420 {
 421   debug_only( verify_construction() );
 422   NOT_PRODUCT(nodes_created++);
 423   assert( is_not_dead(n0), "can not use dead node");
 424   assert( is_not_dead(n1), "can not use dead node");
 425   assert( is_not_dead(n2), "can not use dead node");
 426   assert( is_not_dead(n3), "can not use dead node");
 427   assert( is_not_dead(n4), "can not use dead node");
 428   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 429   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 430   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 431   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 432   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 433 }
 434 
 435 //------------------------------Node-------------------------------------------
 436 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 437                      Node *n4, Node *n5)
 438   : _idx(Init(6))
 439 #ifdef ASSERT
 440   , _parse_idx(_idx)
 441 #endif
 442 {
 443   debug_only( verify_construction() );
 444   NOT_PRODUCT(nodes_created++);
 445   assert( is_not_dead(n0), "can not use dead node");
 446   assert( is_not_dead(n1), "can not use dead node");
 447   assert( is_not_dead(n2), "can not use dead node");
 448   assert( is_not_dead(n3), "can not use dead node");
 449   assert( is_not_dead(n4), "can not use dead node");
 450   assert( is_not_dead(n5), "can not use dead node");
 451   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 452   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 453   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 454   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 455   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 456   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 457 }
 458 
 459 //------------------------------Node-------------------------------------------
 460 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 461                      Node *n4, Node *n5, Node *n6)
 462   : _idx(Init(7))
 463 #ifdef ASSERT
 464   , _parse_idx(_idx)
 465 #endif
 466 {
 467   debug_only( verify_construction() );
 468   NOT_PRODUCT(nodes_created++);
 469   assert( is_not_dead(n0), "can not use dead node");
 470   assert( is_not_dead(n1), "can not use dead node");
 471   assert( is_not_dead(n2), "can not use dead node");
 472   assert( is_not_dead(n3), "can not use dead node");
 473   assert( is_not_dead(n4), "can not use dead node");
 474   assert( is_not_dead(n5), "can not use dead node");
 475   assert( is_not_dead(n6), "can not use dead node");
 476   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 477   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 478   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 479   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 480   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 481   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 482   _in[6] = n6; if (n6 != NULL) n6->add_out((Node *)this);
 483 }
 484 
 485 #ifdef __clang__
 486 #pragma clang diagnostic pop
 487 #endif
 488 
 489 
 490 //------------------------------clone------------------------------------------
 491 // Clone a Node.
 492 Node *Node::clone() const {
 493   Compile* C = Compile::current();
 494   uint s = size_of();           // Size of inherited Node
 495   Node *n = (Node*)C->node_arena()->AmallocWords(size_of() + _max*sizeof(Node*));
 496   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 497   // Set the new input pointer array
 498   n->_in = (Node**)(((char*)n)+s);
 499   // Cannot share the old output pointer array, so kill it
 500   n->_out = NO_OUT_ARRAY;
 501   // And reset the counters to 0
 502   n->_outcnt = 0;
 503   n->_outmax = 0;
 504   // Unlock this guy, since he is not in any hash table.
 505   debug_only(n->_hash_lock = 0);
 506   // Walk the old node's input list to duplicate its edges
 507   uint i;
 508   for( i = 0; i < len(); i++ ) {
 509     Node *x = in(i);
 510     n->_in[i] = x;
 511     if (x != NULL) x->add_out(n);
 512   }
 513   if (is_macro()) {
 514     C->add_macro_node(n);
 515   }
 516   if (is_expensive()) {
 517     C->add_expensive_node(n);
 518   }
 519   if (for_post_loop_opts_igvn()) {
 520     // Don't add cloned node to Compile::_for_post_loop_opts_igvn list automatically.
 521     // If it is applicable, it will happen anyway when the cloned node is registered with IGVN.
 522     n->remove_flag(Node::NodeFlags::Flag_for_post_loop_opts_igvn);
 523   }
 524   if (n->is_reduction()) {
 525     // Do not copy reduction information. This must be explicitly set by the calling code.
 526     n->remove_flag(Node::Flag_is_reduction);
 527   }
 528   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 529   bs->register_potential_barrier_node(n);
 530 
 531   n->set_idx(C->next_unique()); // Get new unique index as well
 532   NOT_PRODUCT(n->_igv_idx = C->next_igv_idx());
 533   debug_only( n->verify_construction() );
 534   NOT_PRODUCT(nodes_created++);
 535   // Do not patch over the debug_idx of a clone, because it makes it
 536   // impossible to break on the clone's moment of creation.
 537   //debug_only( n->set_debug_idx( debug_idx() ) );
 538 
 539   C->copy_node_notes_to(n, (Node*) this);
 540 
 541   // MachNode clone
 542   uint nopnds;
 543   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 544     MachNode *mach  = n->as_Mach();
 545     MachNode *mthis = this->as_Mach();
 546     // Get address of _opnd_array.
 547     // It should be the same offset since it is the clone of this node.
 548     MachOper **from = mthis->_opnds;
 549     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 550                     pointer_delta((const void*)from,
 551                                   (const void*)(&mthis->_opnds), 1));
 552     mach->_opnds = to;
 553     for ( uint i = 0; i < nopnds; ++i ) {
 554       to[i] = from[i]->clone();
 555     }
 556   }
 557   if (n->is_Call()) {
 558     // CallGenerator is linked to the original node.
 559     CallGenerator* cg = n->as_Call()->generator();
 560     if (cg != NULL) {
 561       CallGenerator* cloned_cg = cg->with_call_node(n->as_Call());
 562       n->as_Call()->set_generator(cloned_cg);
 563 
 564       C->print_inlining_assert_ready();
 565       C->print_inlining_move_to(cg);
 566       C->print_inlining_update(cloned_cg);
 567     }
 568   }
 569   if (n->is_SafePoint()) {
 570     // Scalar replacement and macro expansion might modify the JVMState.
 571     // Clone it to make sure it's not shared between SafePointNodes.
 572     n->as_SafePoint()->clone_jvms(C);
 573     n->as_SafePoint()->clone_replaced_nodes();
 574   }
 575   Compile::current()->record_modified_node(n);
 576   return n;                     // Return the clone
 577 }
 578 
 579 //---------------------------setup_is_top--------------------------------------
 580 // Call this when changing the top node, to reassert the invariants
 581 // required by Node::is_top.  See Compile::set_cached_top_node.
 582 void Node::setup_is_top() {
 583   if (this == (Node*)Compile::current()->top()) {
 584     // This node has just become top.  Kill its out array.
 585     _outcnt = _outmax = 0;
 586     _out = NULL;                           // marker value for top
 587     assert(is_top(), "must be top");
 588   } else {
 589     if (_out == NULL)  _out = NO_OUT_ARRAY;
 590     assert(!is_top(), "must not be top");
 591   }
 592 }
 593 
 594 //------------------------------~Node------------------------------------------
 595 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 596 void Node::destruct(PhaseValues* phase) {
 597   Compile* compile = (phase != NULL) ? phase->C : Compile::current();
 598   if (phase != NULL && phase->is_IterGVN()) {
 599     phase->is_IterGVN()->_worklist.remove(this);
 600   }
 601   // If this is the most recently created node, reclaim its index. Otherwise,
 602   // record the node as dead to keep liveness information accurate.
 603   if ((uint)_idx+1 == compile->unique()) {
 604     compile->set_unique(compile->unique()-1);
 605   } else {
 606     compile->record_dead_node(_idx);
 607   }
 608   // Clear debug info:
 609   Node_Notes* nn = compile->node_notes_at(_idx);
 610   if (nn != NULL)  nn->clear();
 611   // Walk the input array, freeing the corresponding output edges
 612   _cnt = _max;  // forget req/prec distinction
 613   uint i;
 614   for( i = 0; i < _max; i++ ) {
 615     set_req(i, NULL);
 616     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 617   }
 618   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 619   // See if the input array was allocated just prior to the object
 620   int edge_size = _max*sizeof(void*);
 621   int out_edge_size = _outmax*sizeof(void*);
 622   char *edge_end = ((char*)_in) + edge_size;
 623   char *out_array = (char*)(_out == NO_OUT_ARRAY? NULL: _out);
 624   int node_size = size_of();
 625 
 626   // Free the output edge array
 627   if (out_edge_size > 0) {
 628     compile->node_arena()->Afree(out_array, out_edge_size);
 629   }
 630 
 631   // Free the input edge array and the node itself
 632   if( edge_end == (char*)this ) {
 633     // It was; free the input array and object all in one hit
 634 #ifndef ASSERT
 635     compile->node_arena()->Afree(_in,edge_size+node_size);
 636 #endif
 637   } else {
 638     // Free just the input array
 639     compile->node_arena()->Afree(_in,edge_size);
 640 
 641     // Free just the object
 642 #ifndef ASSERT
 643     compile->node_arena()->Afree(this,node_size);
 644 #endif
 645   }
 646   if (is_macro()) {
 647     compile->remove_macro_node(this);
 648   }
 649   if (is_expensive()) {
 650     compile->remove_expensive_node(this);
 651   }
 652   if (Opcode() == Op_Opaque4) {
 653     compile->remove_skeleton_predicate_opaq(this);
 654   }
 655   if (for_post_loop_opts_igvn()) {
 656     compile->remove_from_post_loop_opts_igvn(this);
 657   }
 658 
 659   if (is_SafePoint()) {
 660     as_SafePoint()->delete_replaced_nodes();
 661 
 662     if (is_CallStaticJava()) {
 663       compile->remove_unstable_if_trap(as_CallStaticJava(), false);
 664     }
 665   }
 666   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 667   bs->unregister_potential_barrier_node(this);
 668 #ifdef ASSERT
 669   // We will not actually delete the storage, but we'll make the node unusable.
 670   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 671   _in = _out = (Node**) badAddress;
 672   _max = _cnt = _outmax = _outcnt = 0;
 673   compile->remove_modified_node(this);
 674 #endif
 675 }
 676 
 677 //------------------------------grow-------------------------------------------
 678 // Grow the input array, making space for more edges
 679 void Node::grow(uint len) {
 680   Arena* arena = Compile::current()->node_arena();
 681   uint new_max = _max;
 682   if( new_max == 0 ) {
 683     _max = 4;
 684     _in = (Node**)arena->Amalloc(4*sizeof(Node*));
 685     Node** to = _in;
 686     to[0] = NULL;
 687     to[1] = NULL;
 688     to[2] = NULL;
 689     to[3] = NULL;
 690     return;
 691   }
 692   new_max = next_power_of_2(len);
 693   // Trimming to limit allows a uint8 to handle up to 255 edges.
 694   // Previously I was using only powers-of-2 which peaked at 128 edges.
 695   //if( new_max >= limit ) new_max = limit-1;
 696   _in = (Node**)arena->Arealloc(_in, _max*sizeof(Node*), new_max*sizeof(Node*));
 697   Copy::zero_to_bytes(&_in[_max], (new_max-_max)*sizeof(Node*)); // NULL all new space
 698   _max = new_max;               // Record new max length
 699   // This assertion makes sure that Node::_max is wide enough to
 700   // represent the numerical value of new_max.
 701   assert(_max == new_max && _max > len, "int width of _max is too small");
 702 }
 703 
 704 //-----------------------------out_grow----------------------------------------
 705 // Grow the input array, making space for more edges
 706 void Node::out_grow( uint len ) {
 707   assert(!is_top(), "cannot grow a top node's out array");
 708   Arena* arena = Compile::current()->node_arena();
 709   uint new_max = _outmax;
 710   if( new_max == 0 ) {
 711     _outmax = 4;
 712     _out = (Node **)arena->Amalloc(4*sizeof(Node*));
 713     return;
 714   }
 715   new_max = next_power_of_2(len);
 716   // Trimming to limit allows a uint8 to handle up to 255 edges.
 717   // Previously I was using only powers-of-2 which peaked at 128 edges.
 718   //if( new_max >= limit ) new_max = limit-1;
 719   assert(_out != NULL && _out != NO_OUT_ARRAY, "out must have sensible value");
 720   _out = (Node**)arena->Arealloc(_out,_outmax*sizeof(Node*),new_max*sizeof(Node*));
 721   //Copy::zero_to_bytes(&_out[_outmax], (new_max-_outmax)*sizeof(Node*)); // NULL all new space
 722   _outmax = new_max;               // Record new max length
 723   // This assertion makes sure that Node::_max is wide enough to
 724   // represent the numerical value of new_max.
 725   assert(_outmax == new_max && _outmax > len, "int width of _outmax is too small");
 726 }
 727 
 728 #ifdef ASSERT
 729 //------------------------------is_dead----------------------------------------
 730 bool Node::is_dead() const {
 731   // Mach and pinch point nodes may look like dead.
 732   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 733     return false;
 734   for( uint i = 0; i < _max; i++ )
 735     if( _in[i] != NULL )
 736       return false;
 737   return true;
 738 }
 739 
 740 bool Node::is_reachable_from_root() const {
 741   ResourceMark rm;
 742   Unique_Node_List wq;
 743   wq.push((Node*)this);
 744   RootNode* root = Compile::current()->root();
 745   for (uint i = 0; i < wq.size(); i++) {
 746     Node* m = wq.at(i);
 747     if (m == root) {
 748       return true;
 749     }
 750     for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
 751       Node* u = m->fast_out(j);
 752       wq.push(u);
 753     }
 754   }
 755   return false;
 756 }
 757 #endif
 758 
 759 //------------------------------is_unreachable---------------------------------
 760 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 761   assert(!is_Mach(), "doesn't work with MachNodes");
 762   return outcnt() == 0 || igvn.type(this) == Type::TOP || (in(0) != NULL && in(0)->is_top());
 763 }
 764 
 765 //------------------------------add_req----------------------------------------
 766 // Add a new required input at the end
 767 void Node::add_req( Node *n ) {
 768   assert( is_not_dead(n), "can not use dead node");
 769 
 770   // Look to see if I can move precedence down one without reallocating
 771   if( (_cnt >= _max) || (in(_max-1) != NULL) )
 772     grow( _max+1 );
 773 
 774   // Find a precedence edge to move
 775   if( in(_cnt) != NULL ) {       // Next precedence edge is busy?
 776     uint i;
 777     for( i=_cnt; i<_max; i++ )
 778       if( in(i) == NULL )       // Find the NULL at end of prec edge list
 779         break;                  // There must be one, since we grew the array
 780     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 781   }
 782   _in[_cnt++] = n;            // Stuff over old prec edge
 783   if (n != NULL) n->add_out((Node *)this);
 784   Compile::current()->record_modified_node(this);
 785 }
 786 
 787 //---------------------------add_req_batch-------------------------------------
 788 // Add a new required input at the end
 789 void Node::add_req_batch( Node *n, uint m ) {
 790   assert( is_not_dead(n), "can not use dead node");
 791   // check various edge cases
 792   if ((int)m <= 1) {
 793     assert((int)m >= 0, "oob");
 794     if (m != 0)  add_req(n);
 795     return;
 796   }
 797 
 798   // Look to see if I can move precedence down one without reallocating
 799   if( (_cnt+m) > _max || _in[_max-m] )
 800     grow( _max+m );
 801 
 802   // Find a precedence edge to move
 803   if( _in[_cnt] != NULL ) {     // Next precedence edge is busy?
 804     uint i;
 805     for( i=_cnt; i<_max; i++ )
 806       if( _in[i] == NULL )      // Find the NULL at end of prec edge list
 807         break;                  // There must be one, since we grew the array
 808     // Slide all the precs over by m positions (assume #prec << m).
 809     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 810   }
 811 
 812   // Stuff over the old prec edges
 813   for(uint i=0; i<m; i++ ) {
 814     _in[_cnt++] = n;
 815   }
 816 
 817   // Insert multiple out edges on the node.
 818   if (n != NULL && !n->is_top()) {
 819     for(uint i=0; i<m; i++ ) {
 820       n->add_out((Node *)this);
 821     }
 822   }
 823   Compile::current()->record_modified_node(this);
 824 }
 825 
 826 //------------------------------del_req----------------------------------------
 827 // Delete the required edge and compact the edge array
 828 void Node::del_req( uint idx ) {
 829   assert( idx < _cnt, "oob");
 830   assert( !VerifyHashTableKeys || _hash_lock == 0,
 831           "remove node from hash table before modifying it");
 832   // First remove corresponding def-use edge
 833   Node *n = in(idx);
 834   if (n != NULL) n->del_out((Node *)this);
 835   _in[idx] = in(--_cnt); // Compact the array
 836   // Avoid spec violation: Gap in prec edges.
 837   close_prec_gap_at(_cnt);
 838   Compile::current()->record_modified_node(this);
 839 }
 840 
 841 //------------------------------del_req_ordered--------------------------------
 842 // Delete the required edge and compact the edge array with preserved order
 843 void Node::del_req_ordered( uint idx ) {
 844   assert( idx < _cnt, "oob");
 845   assert( !VerifyHashTableKeys || _hash_lock == 0,
 846           "remove node from hash table before modifying it");
 847   // First remove corresponding def-use edge
 848   Node *n = in(idx);
 849   if (n != NULL) n->del_out((Node *)this);
 850   if (idx < --_cnt) {    // Not last edge ?
 851     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
 852   }
 853   // Avoid spec violation: Gap in prec edges.
 854   close_prec_gap_at(_cnt);
 855   Compile::current()->record_modified_node(this);
 856 }
 857 
 858 //------------------------------ins_req----------------------------------------
 859 // Insert a new required input at the end
 860 void Node::ins_req( uint idx, Node *n ) {
 861   assert( is_not_dead(n), "can not use dead node");
 862   add_req(NULL);                // Make space
 863   assert( idx < _max, "Must have allocated enough space");
 864   // Slide over
 865   if(_cnt-idx-1 > 0) {
 866     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 867   }
 868   _in[idx] = n;                            // Stuff over old required edge
 869   if (n != NULL) n->add_out((Node *)this); // Add reciprocal def-use edge
 870   Compile::current()->record_modified_node(this);
 871 }
 872 
 873 //-----------------------------find_edge---------------------------------------
 874 int Node::find_edge(Node* n) {
 875   for (uint i = 0; i < len(); i++) {
 876     if (_in[i] == n)  return i;
 877   }
 878   return -1;
 879 }
 880 
 881 //----------------------------replace_edge-------------------------------------
 882 int Node::replace_edge(Node* old, Node* neww, PhaseGVN* gvn) {
 883   if (old == neww)  return 0;  // nothing to do
 884   uint nrep = 0;
 885   for (uint i = 0; i < len(); i++) {
 886     if (in(i) == old) {
 887       if (i < req()) {
 888         if (gvn != NULL) {
 889           set_req_X(i, neww, gvn);
 890         } else {
 891           set_req(i, neww);
 892         }
 893       } else {
 894         assert(gvn == NULL || gvn->is_IterGVN() == NULL, "no support for igvn here");
 895         assert(find_prec_edge(neww) == -1, "spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx);
 896         set_prec(i, neww);
 897       }
 898       nrep++;
 899     }
 900   }
 901   return nrep;
 902 }
 903 
 904 /**
 905  * Replace input edges in the range pointing to 'old' node.
 906  */
 907 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end, PhaseGVN* gvn) {
 908   if (old == neww)  return 0;  // nothing to do
 909   uint nrep = 0;
 910   for (int i = start; i < end; i++) {
 911     if (in(i) == old) {
 912       set_req_X(i, neww, gvn);
 913       nrep++;
 914     }
 915   }
 916   return nrep;
 917 }
 918 
 919 //-------------------------disconnect_inputs-----------------------------------
 920 // NULL out all inputs to eliminate incoming Def-Use edges.
 921 void Node::disconnect_inputs(Compile* C) {
 922   // the layout of Node::_in
 923   // r: a required input, null is allowed
 924   // p: a precedence, null values are all at the end
 925   // -----------------------------------
 926   // |r|...|r|p|...|p|null|...|null|
 927   //         |                     |
 928   //         req()                 len()
 929   // -----------------------------------
 930   for (uint i = 0; i < req(); ++i) {
 931     if (in(i) != nullptr) {
 932       set_req(i, nullptr);
 933     }
 934   }
 935 
 936   // Remove precedence edges if any exist
 937   // Note: Safepoints may have precedence edges, even during parsing
 938   for (uint i = len(); i > req(); ) {
 939     rm_prec(--i);  // no-op if _in[i] is nullptr
 940   }
 941 
 942 #ifdef ASSERT
 943   // sanity check
 944   for (uint i = 0; i < len(); ++i) {
 945     assert(_in[i] == nullptr, "disconnect_inputs() failed!");
 946   }
 947 #endif
 948 
 949   // Node::destruct requires all out edges be deleted first
 950   // debug_only(destruct();)   // no reuse benefit expected
 951   C->record_dead_node(_idx);
 952 }
 953 
 954 //-----------------------------uncast---------------------------------------
 955 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 956 // Strip away casting.  (It is depth-limited.)
 957 // Optionally, keep casts with dependencies.
 958 Node* Node::uncast(bool keep_deps) const {
 959   // Should be inline:
 960   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 961   if (is_ConstraintCast()) {
 962     return uncast_helper(this, keep_deps);
 963   } else {
 964     return (Node*) this;
 965   }
 966 }
 967 
 968 // Find out of current node that matches opcode.
 969 Node* Node::find_out_with(int opcode) {
 970   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 971     Node* use = fast_out(i);
 972     if (use->Opcode() == opcode) {
 973       return use;
 974     }
 975   }
 976   return NULL;
 977 }
 978 
 979 // Return true if the current node has an out that matches opcode.
 980 bool Node::has_out_with(int opcode) {
 981   return (find_out_with(opcode) != NULL);
 982 }
 983 
 984 // Return true if the current node has an out that matches any of the opcodes.
 985 bool Node::has_out_with(int opcode1, int opcode2, int opcode3, int opcode4) {
 986   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 987       int opcode = fast_out(i)->Opcode();
 988       if (opcode == opcode1 || opcode == opcode2 || opcode == opcode3 || opcode == opcode4) {
 989         return true;
 990       }
 991   }
 992   return false;
 993 }
 994 
 995 
 996 //---------------------------uncast_helper-------------------------------------
 997 Node* Node::uncast_helper(const Node* p, bool keep_deps) {
 998 #ifdef ASSERT
 999   uint depth_count = 0;
1000   const Node* orig_p = p;
1001 #endif
1002 
1003   while (true) {
1004 #ifdef ASSERT
1005     if (depth_count >= K) {
1006       orig_p->dump(4);
1007       if (p != orig_p)
1008         p->dump(1);
1009     }
1010     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
1011 #endif
1012     if (p == NULL || p->req() != 2) {
1013       break;
1014     } else if (p->is_ConstraintCast()) {
1015       if (keep_deps && p->as_ConstraintCast()->carry_dependency()) {
1016         break; // stop at casts with dependencies
1017       }
1018       p = p->in(1);
1019     } else {
1020       break;
1021     }
1022   }
1023   return (Node*) p;
1024 }
1025 
1026 //------------------------------add_prec---------------------------------------
1027 // Add a new precedence input.  Precedence inputs are unordered, with
1028 // duplicates removed and NULLs packed down at the end.
1029 void Node::add_prec( Node *n ) {
1030   assert( is_not_dead(n), "can not use dead node");
1031 
1032   // Check for NULL at end
1033   if( _cnt >= _max || in(_max-1) )
1034     grow( _max+1 );
1035 
1036   // Find a precedence edge to move
1037   uint i = _cnt;
1038   while( in(i) != NULL ) {
1039     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
1040     i++;
1041   }
1042   _in[i] = n;                                // Stuff prec edge over NULL
1043   if ( n != NULL) n->add_out((Node *)this);  // Add mirror edge
1044 
1045 #ifdef ASSERT
1046   while ((++i)<_max) { assert(_in[i] == NULL, "spec violation: Gap in prec edges (node %d)", _idx); }
1047 #endif
1048   Compile::current()->record_modified_node(this);
1049 }
1050 
1051 //------------------------------rm_prec----------------------------------------
1052 // Remove a precedence input.  Precedence inputs are unordered, with
1053 // duplicates removed and NULLs packed down at the end.
1054 void Node::rm_prec( uint j ) {
1055   assert(j < _max, "oob: i=%d, _max=%d", j, _max);
1056   assert(j >= _cnt, "not a precedence edge");
1057   if (_in[j] == NULL) return;   // Avoid spec violation: Gap in prec edges.
1058   _in[j]->del_out((Node *)this);
1059   close_prec_gap_at(j);
1060   Compile::current()->record_modified_node(this);
1061 }
1062 
1063 //------------------------------size_of----------------------------------------
1064 uint Node::size_of() const { return sizeof(*this); }
1065 
1066 //------------------------------ideal_reg--------------------------------------
1067 uint Node::ideal_reg() const { return 0; }
1068 
1069 //------------------------------jvms-------------------------------------------
1070 JVMState* Node::jvms() const { return NULL; }
1071 
1072 #ifdef ASSERT
1073 //------------------------------jvms-------------------------------------------
1074 bool Node::verify_jvms(const JVMState* using_jvms) const {
1075   for (JVMState* jvms = this->jvms(); jvms != NULL; jvms = jvms->caller()) {
1076     if (jvms == using_jvms)  return true;
1077   }
1078   return false;
1079 }
1080 
1081 //------------------------------init_NodeProperty------------------------------
1082 void Node::init_NodeProperty() {
1083   assert(_max_classes <= max_juint, "too many NodeProperty classes");
1084   assert(max_flags() <= max_juint, "too many NodeProperty flags");
1085 }
1086 
1087 //-----------------------------max_flags---------------------------------------
1088 juint Node::max_flags() {
1089   return (PD::_last_flag << 1) - 1; // allow flags combination
1090 }
1091 #endif
1092 
1093 //------------------------------format-----------------------------------------
1094 // Print as assembly
1095 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1096 //------------------------------emit-------------------------------------------
1097 // Emit bytes starting at parameter 'ptr'.
1098 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
1099 //------------------------------size-------------------------------------------
1100 // Size of instruction in bytes
1101 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1102 
1103 //------------------------------CFG Construction-------------------------------
1104 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1105 // Goto and Return.
1106 const Node *Node::is_block_proj() const { return 0; }
1107 
1108 // Minimum guaranteed type
1109 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1110 
1111 
1112 //------------------------------raise_bottom_type------------------------------
1113 // Get the worst-case Type output for this Node.
1114 void Node::raise_bottom_type(const Type* new_type) {
1115   if (is_Type()) {
1116     TypeNode *n = this->as_Type();
1117     if (VerifyAliases) {
1118       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1119     }
1120     n->set_type(new_type);
1121   } else if (is_Load()) {
1122     LoadNode *n = this->as_Load();
1123     if (VerifyAliases) {
1124       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1125     }
1126     n->set_type(new_type);
1127   }
1128 }
1129 
1130 //------------------------------Identity---------------------------------------
1131 // Return a node that the given node is equivalent to.
1132 Node* Node::Identity(PhaseGVN* phase) {
1133   return this;                  // Default to no identities
1134 }
1135 
1136 //------------------------------Value------------------------------------------
1137 // Compute a new Type for a node using the Type of the inputs.
1138 const Type* Node::Value(PhaseGVN* phase) const {
1139   return bottom_type();         // Default to worst-case Type
1140 }
1141 
1142 //------------------------------Ideal------------------------------------------
1143 //
1144 // 'Idealize' the graph rooted at this Node.
1145 //
1146 // In order to be efficient and flexible there are some subtle invariants
1147 // these Ideal calls need to hold.  Running with '+VerifyIterativeGVN' checks
1148 // these invariants, although its too slow to have on by default.  If you are
1149 // hacking an Ideal call, be sure to test with +VerifyIterativeGVN!
1150 //
1151 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1152 // pointer.  If ANY change is made, it must return the root of the reshaped
1153 // graph - even if the root is the same Node.  Example: swapping the inputs
1154 // to an AddINode gives the same answer and same root, but you still have to
1155 // return the 'this' pointer instead of NULL.
1156 //
1157 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1158 // Identity call to return an old Node; basically if Identity can find
1159 // another Node have the Ideal call make no change and return NULL.
1160 // Example: AddINode::Ideal must check for add of zero; in this case it
1161 // returns NULL instead of doing any graph reshaping.
1162 //
1163 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1164 // sharing there may be other users of the old Nodes relying on their current
1165 // semantics.  Modifying them will break the other users.
1166 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1167 // "X+3" unchanged in case it is shared.
1168 //
1169 // If you modify the 'this' pointer's inputs, you should use
1170 // 'set_req'.  If you are making a new Node (either as the new root or
1171 // some new internal piece) you may use 'init_req' to set the initial
1172 // value.  You can make a new Node with either 'new' or 'clone'.  In
1173 // either case, def-use info is correctly maintained.
1174 //
1175 // Example: reshape "(X+3)+4" into "X+7":
1176 //    set_req(1, in(1)->in(1));
1177 //    set_req(2, phase->intcon(7));
1178 //    return this;
1179 // Example: reshape "X*4" into "X<<2"
1180 //    return new LShiftINode(in(1), phase->intcon(2));
1181 //
1182 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1183 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1184 //    Node *shift=phase->transform(new LShiftINode(in(1),phase->intcon(5)));
1185 //    return new AddINode(shift, in(1));
1186 //
1187 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1188 // These forms are faster than 'phase->transform(new ConNode())' and Do
1189 // The Right Thing with def-use info.
1190 //
1191 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1192 // graph uses the 'this' Node it must be the root.  If you want a Node with
1193 // the same Opcode as the 'this' pointer use 'clone'.
1194 //
1195 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1196   return NULL;                  // Default to being Ideal already
1197 }
1198 
1199 // Some nodes have specific Ideal subgraph transformations only if they are
1200 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1201 // for the transformations to happen.
1202 bool Node::has_special_unique_user() const {
1203   assert(outcnt() == 1, "match only for unique out");
1204   Node* n = unique_out();
1205   int op  = Opcode();
1206   if (this->is_Store()) {
1207     // Condition for back-to-back stores folding.
1208     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1209   } else if (this->is_Load() || this->is_DecodeN() || this->is_Phi()) {
1210     // Condition for removing an unused LoadNode or DecodeNNode from the MemBarAcquire precedence input
1211     return n->Opcode() == Op_MemBarAcquire;
1212   } else if (op == Op_AddL) {
1213     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1214     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1215   } else if (op == Op_SubI || op == Op_SubL) {
1216     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1217     return n->Opcode() == op && n->in(2) == this;
1218   } else if (is_If() && (n->is_IfFalse() || n->is_IfTrue())) {
1219     // See IfProjNode::Identity()
1220     return true;
1221   } else if ((is_IfFalse() || is_IfTrue()) && n->is_If()) {
1222     // See IfNode::fold_compares
1223     return true;
1224   } else {
1225     return false;
1226   }
1227 };
1228 
1229 //--------------------------find_exact_control---------------------------------
1230 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1231 Node* Node::find_exact_control(Node* ctrl) {
1232   if (ctrl == NULL && this->is_Region())
1233     ctrl = this->as_Region()->is_copy();
1234 
1235   if (ctrl != NULL && ctrl->is_CatchProj()) {
1236     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1237       ctrl = ctrl->in(0);
1238     if (ctrl != NULL && !ctrl->is_top())
1239       ctrl = ctrl->in(0);
1240   }
1241 
1242   if (ctrl != NULL && ctrl->is_Proj())
1243     ctrl = ctrl->in(0);
1244 
1245   return ctrl;
1246 }
1247 
1248 //--------------------------dominates------------------------------------------
1249 // Helper function for MemNode::all_controls_dominate().
1250 // Check if 'this' control node dominates or equal to 'sub' control node.
1251 // We already know that if any path back to Root or Start reaches 'this',
1252 // then all paths so, so this is a simple search for one example,
1253 // not an exhaustive search for a counterexample.
1254 bool Node::dominates(Node* sub, Node_List &nlist) {
1255   assert(this->is_CFG(), "expecting control");
1256   assert(sub != NULL && sub->is_CFG(), "expecting control");
1257 
1258   // detect dead cycle without regions
1259   int iterations_without_region_limit = DominatorSearchLimit;
1260 
1261   Node* orig_sub = sub;
1262   Node* dom      = this;
1263   bool  met_dom  = false;
1264   nlist.clear();
1265 
1266   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1267   // After seeing 'dom', continue up to Root or Start.
1268   // If we hit a region (backward split point), it may be a loop head.
1269   // Keep going through one of the region's inputs.  If we reach the
1270   // same region again, go through a different input.  Eventually we
1271   // will either exit through the loop head, or give up.
1272   // (If we get confused, break out and return a conservative 'false'.)
1273   while (sub != NULL) {
1274     if (sub->is_top())  break; // Conservative answer for dead code.
1275     if (sub == dom) {
1276       if (nlist.size() == 0) {
1277         // No Region nodes except loops were visited before and the EntryControl
1278         // path was taken for loops: it did not walk in a cycle.
1279         return true;
1280       } else if (met_dom) {
1281         break;          // already met before: walk in a cycle
1282       } else {
1283         // Region nodes were visited. Continue walk up to Start or Root
1284         // to make sure that it did not walk in a cycle.
1285         met_dom = true; // first time meet
1286         iterations_without_region_limit = DominatorSearchLimit; // Reset
1287      }
1288     }
1289     if (sub->is_Start() || sub->is_Root()) {
1290       // Success if we met 'dom' along a path to Start or Root.
1291       // We assume there are no alternative paths that avoid 'dom'.
1292       // (This assumption is up to the caller to ensure!)
1293       return met_dom;
1294     }
1295     Node* up = sub->in(0);
1296     // Normalize simple pass-through regions and projections:
1297     up = sub->find_exact_control(up);
1298     // If sub == up, we found a self-loop.  Try to push past it.
1299     if (sub == up && sub->is_Loop()) {
1300       // Take loop entry path on the way up to 'dom'.
1301       up = sub->in(1); // in(LoopNode::EntryControl);
1302     } else if (sub == up && sub->is_Region() && sub->req() == 2) {
1303       // Take in(1) path on the way up to 'dom' for regions with only one input
1304       up = sub->in(1);
1305     } else if (sub == up && sub->is_Region() && sub->req() == 3) {
1306       // Try both paths for Regions with 2 input paths (it may be a loop head).
1307       // It could give conservative 'false' answer without information
1308       // which region's input is the entry path.
1309       iterations_without_region_limit = DominatorSearchLimit; // Reset
1310 
1311       bool region_was_visited_before = false;
1312       // Was this Region node visited before?
1313       // If so, we have reached it because we accidentally took a
1314       // loop-back edge from 'sub' back into the body of the loop,
1315       // and worked our way up again to the loop header 'sub'.
1316       // So, take the first unexplored path on the way up to 'dom'.
1317       for (int j = nlist.size() - 1; j >= 0; j--) {
1318         intptr_t ni = (intptr_t)nlist.at(j);
1319         Node* visited = (Node*)(ni & ~1);
1320         bool  visited_twice_already = ((ni & 1) != 0);
1321         if (visited == sub) {
1322           if (visited_twice_already) {
1323             // Visited 2 paths, but still stuck in loop body.  Give up.
1324             return false;
1325           }
1326           // The Region node was visited before only once.
1327           // (We will repush with the low bit set, below.)
1328           nlist.remove(j);
1329           // We will find a new edge and re-insert.
1330           region_was_visited_before = true;
1331           break;
1332         }
1333       }
1334 
1335       // Find an incoming edge which has not been seen yet; walk through it.
1336       assert(up == sub, "");
1337       uint skip = region_was_visited_before ? 1 : 0;
1338       for (uint i = 1; i < sub->req(); i++) {
1339         Node* in = sub->in(i);
1340         if (in != NULL && !in->is_top() && in != sub) {
1341           if (skip == 0) {
1342             up = in;
1343             break;
1344           }
1345           --skip;               // skip this nontrivial input
1346         }
1347       }
1348 
1349       // Set 0 bit to indicate that both paths were taken.
1350       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1351     }
1352 
1353     if (up == sub) {
1354       break;    // some kind of tight cycle
1355     }
1356     if (up == orig_sub && met_dom) {
1357       // returned back after visiting 'dom'
1358       break;    // some kind of cycle
1359     }
1360     if (--iterations_without_region_limit < 0) {
1361       break;    // dead cycle
1362     }
1363     sub = up;
1364   }
1365 
1366   // Did not meet Root or Start node in pred. chain.
1367   // Conservative answer for dead code.
1368   return false;
1369 }
1370 
1371 //------------------------------remove_dead_region-----------------------------
1372 // This control node is dead.  Follow the subgraph below it making everything
1373 // using it dead as well.  This will happen normally via the usual IterGVN
1374 // worklist but this call is more efficient.  Do not update use-def info
1375 // inside the dead region, just at the borders.
1376 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1377   // Con's are a popular node to re-hit in the hash table again.
1378   if( dead->is_Con() ) return;
1379 
1380   ResourceMark rm;
1381   Node_List nstack;
1382 
1383   Node *top = igvn->C->top();
1384   nstack.push(dead);
1385   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1386 
1387   while (nstack.size() > 0) {
1388     dead = nstack.pop();
1389     if (dead->Opcode() == Op_SafePoint) {
1390       dead->as_SafePoint()->disconnect_from_root(igvn);
1391     }
1392     if (dead->outcnt() > 0) {
1393       // Keep dead node on stack until all uses are processed.
1394       nstack.push(dead);
1395       // For all Users of the Dead...    ;-)
1396       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1397         Node* use = dead->last_out(k);
1398         igvn->hash_delete(use);       // Yank from hash table prior to mod
1399         if (use->in(0) == dead) {     // Found another dead node
1400           assert (!use->is_Con(), "Control for Con node should be Root node.");
1401           use->set_req(0, top);       // Cut dead edge to prevent processing
1402           nstack.push(use);           // the dead node again.
1403         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1404                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1405                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1406           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1407           use->set_req(0, top);       // Cut self edge
1408           nstack.push(use);
1409         } else {                      // Else found a not-dead user
1410           // Dead if all inputs are top or null
1411           bool dead_use = !use->is_Root(); // Keep empty graph alive
1412           for (uint j = 1; j < use->req(); j++) {
1413             Node* in = use->in(j);
1414             if (in == dead) {         // Turn all dead inputs into TOP
1415               use->set_req(j, top);
1416             } else if (in != NULL && !in->is_top()) {
1417               dead_use = false;
1418             }
1419           }
1420           if (dead_use) {
1421             if (use->is_Region()) {
1422               use->set_req(0, top);   // Cut self edge
1423             }
1424             nstack.push(use);
1425           } else {
1426             igvn->_worklist.push(use);
1427           }
1428         }
1429         // Refresh the iterator, since any number of kills might have happened.
1430         k = dead->last_outs(kmin);
1431       }
1432     } else { // (dead->outcnt() == 0)
1433       // Done with outputs.
1434       igvn->hash_delete(dead);
1435       igvn->_worklist.remove(dead);
1436       igvn->set_type(dead, Type::TOP);
1437       // Kill all inputs to the dead guy
1438       for (uint i=0; i < dead->req(); i++) {
1439         Node *n = dead->in(i);      // Get input to dead guy
1440         if (n != NULL && !n->is_top()) { // Input is valid?
1441           dead->set_req(i, top);    // Smash input away
1442           if (n->outcnt() == 0) {   // Input also goes dead?
1443             if (!n->is_Con())
1444               nstack.push(n);       // Clear it out as well
1445           } else if (n->outcnt() == 1 &&
1446                      n->has_special_unique_user()) {
1447             igvn->add_users_to_worklist( n );
1448           } else if (n->outcnt() <= 2 && n->is_Store()) {
1449             // Push store's uses on worklist to enable folding optimization for
1450             // store/store and store/load to the same address.
1451             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1452             // and remove_globally_dead_node().
1453             igvn->add_users_to_worklist( n );
1454           } else {
1455             BarrierSet::barrier_set()->barrier_set_c2()->enqueue_useful_gc_barrier(igvn, n);
1456           }
1457         }
1458       }
1459       igvn->C->remove_useless_node(dead);
1460     } // (dead->outcnt() == 0)
1461   }   // while (nstack.size() > 0) for outputs
1462   return;
1463 }
1464 
1465 //------------------------------remove_dead_region-----------------------------
1466 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1467   Node *n = in(0);
1468   if( !n ) return false;
1469   // Lost control into this guy?  I.e., it became unreachable?
1470   // Aggressively kill all unreachable code.
1471   if (can_reshape && n->is_top()) {
1472     kill_dead_code(this, phase->is_IterGVN());
1473     return false; // Node is dead.
1474   }
1475 
1476   if( n->is_Region() && n->as_Region()->is_copy() ) {
1477     Node *m = n->nonnull_req();
1478     set_req(0, m);
1479     return true;
1480   }
1481   return false;
1482 }
1483 
1484 //------------------------------hash-------------------------------------------
1485 // Hash function over Nodes.
1486 uint Node::hash() const {
1487   uint sum = 0;
1488   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1489     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded NULLs
1490   return (sum>>2) + _cnt + Opcode();
1491 }
1492 
1493 //------------------------------cmp--------------------------------------------
1494 // Compare special parts of simple Nodes
1495 bool Node::cmp( const Node &n ) const {
1496   return true;                  // Must be same
1497 }
1498 
1499 //------------------------------rematerialize-----------------------------------
1500 // Should we clone rather than spill this instruction?
1501 bool Node::rematerialize() const {
1502   if ( is_Mach() )
1503     return this->as_Mach()->rematerialize();
1504   else
1505     return (_flags & Flag_rematerialize) != 0;
1506 }
1507 
1508 //------------------------------needs_anti_dependence_check---------------------
1509 // Nodes which use memory without consuming it, hence need antidependences.
1510 bool Node::needs_anti_dependence_check() const {
1511   if (req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0) {
1512     return false;
1513   }
1514   return in(1)->bottom_type()->has_memory();
1515 }
1516 
1517 // Get an integer constant from a ConNode (or CastIINode).
1518 // Return a default value if there is no apparent constant here.
1519 const TypeInt* Node::find_int_type() const {
1520   if (this->is_Type()) {
1521     return this->as_Type()->type()->isa_int();
1522   } else if (this->is_Con()) {
1523     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1524     return this->bottom_type()->isa_int();
1525   }
1526   return NULL;
1527 }
1528 
1529 const TypeInteger* Node::find_integer_type(BasicType bt) const {
1530   if (this->is_Type()) {
1531     return this->as_Type()->type()->isa_integer(bt);
1532   } else if (this->is_Con()) {
1533     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1534     return this->bottom_type()->isa_integer(bt);
1535   }
1536   return NULL;
1537 }
1538 
1539 // Get a pointer constant from a ConstNode.
1540 // Returns the constant if it is a pointer ConstNode
1541 intptr_t Node::get_ptr() const {
1542   assert( Opcode() == Op_ConP, "" );
1543   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1544 }
1545 
1546 // Get a narrow oop constant from a ConNNode.
1547 intptr_t Node::get_narrowcon() const {
1548   assert( Opcode() == Op_ConN, "" );
1549   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1550 }
1551 
1552 // Get a long constant from a ConNode.
1553 // Return a default value if there is no apparent constant here.
1554 const TypeLong* Node::find_long_type() const {
1555   if (this->is_Type()) {
1556     return this->as_Type()->type()->isa_long();
1557   } else if (this->is_Con()) {
1558     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1559     return this->bottom_type()->isa_long();
1560   }
1561   return NULL;
1562 }
1563 
1564 
1565 /**
1566  * Return a ptr type for nodes which should have it.
1567  */
1568 const TypePtr* Node::get_ptr_type() const {
1569   const TypePtr* tp = this->bottom_type()->make_ptr();
1570 #ifdef ASSERT
1571   if (tp == NULL) {
1572     this->dump(1);
1573     assert((tp != NULL), "unexpected node type");
1574   }
1575 #endif
1576   return tp;
1577 }
1578 
1579 // Get a double constant from a ConstNode.
1580 // Returns the constant if it is a double ConstNode
1581 jdouble Node::getd() const {
1582   assert( Opcode() == Op_ConD, "" );
1583   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1584 }
1585 
1586 // Get a float constant from a ConstNode.
1587 // Returns the constant if it is a float ConstNode
1588 jfloat Node::getf() const {
1589   assert( Opcode() == Op_ConF, "" );
1590   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1591 }
1592 
1593 #ifndef PRODUCT
1594 
1595 // Call this from debugger:
1596 Node* old_root() {
1597   Matcher* matcher = Compile::current()->matcher();
1598   if (matcher != nullptr) {
1599     Node* new_root = Compile::current()->root();
1600     Node* old_root = matcher->find_old_node(new_root);
1601     if (old_root != nullptr) {
1602       return old_root;
1603     }
1604   }
1605   tty->print("old_root: not found.\n");
1606   return nullptr;
1607 }
1608 
1609 // BFS traverse all reachable nodes from start, call callback on them
1610 template <typename Callback>
1611 void visit_nodes(Node* start, Callback callback, bool traverse_output, bool only_ctrl) {
1612   Unique_Mixed_Node_List worklist;
1613   worklist.add(start);
1614   for (uint i = 0; i < worklist.size(); i++) {
1615     Node* n = worklist[i];
1616     callback(n);
1617     for (uint i = 0; i < n->len(); i++) {
1618       if (!only_ctrl || n->is_Region() || (n->Opcode() == Op_Root) || (i == TypeFunc::Control)) {
1619         // If only_ctrl is set: Add regions, the root node, or control inputs only
1620         worklist.add(n->in(i));
1621       }
1622     }
1623     if (traverse_output && !only_ctrl) {
1624       for (uint i = 0; i < n->outcnt(); i++) {
1625         worklist.add(n->raw_out(i));
1626       }
1627     }
1628   }
1629 }
1630 
1631 // BFS traverse from start, return node with idx
1632 Node* find_node_by_idx(Node* start, uint idx, bool traverse_output, bool only_ctrl) {
1633   ResourceMark rm;
1634   Node* result = nullptr;
1635   auto callback = [&] (Node* n) {
1636     if (n->_idx == idx) {
1637       if (result != nullptr) {
1638         tty->print("find_node_by_idx: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1639           (uintptr_t)result, (uintptr_t)n, idx);
1640       }
1641       result = n;
1642     }
1643   };
1644   visit_nodes(start, callback, traverse_output, only_ctrl);
1645   return result;
1646 }
1647 
1648 int node_idx_cmp(const Node** n1, const Node** n2) {
1649   return (*n1)->_idx - (*n2)->_idx;
1650 }
1651 
1652 void find_nodes_by_name(Node* start, const char* name) {
1653   ResourceMark rm;
1654   GrowableArray<const Node*> ns;
1655   auto callback = [&] (const Node* n) {
1656     if (StringUtils::is_star_match(name, n->Name())) {
1657       ns.push(n);
1658     }
1659   };
1660   visit_nodes(start, callback, true, false);
1661   ns.sort(node_idx_cmp);
1662   for (int i = 0; i < ns.length(); i++) {
1663     ns.at(i)->dump();
1664   }
1665 }
1666 
1667 void find_nodes_by_dump(Node* start, const char* pattern) {
1668   ResourceMark rm;
1669   GrowableArray<const Node*> ns;
1670   auto callback = [&] (const Node* n) {
1671     stringStream stream;
1672     n->dump("", false, &stream);
1673     if (StringUtils::is_star_match(pattern, stream.base())) {
1674       ns.push(n);
1675     }
1676   };
1677   visit_nodes(start, callback, true, false);
1678   ns.sort(node_idx_cmp);
1679   for (int i = 0; i < ns.length(); i++) {
1680     ns.at(i)->dump();
1681   }
1682 }
1683 
1684 // call from debugger: find node with name pattern in new/current graph
1685 // name can contain "*" in match pattern to match any characters
1686 // the matching is case insensitive
1687 void find_nodes_by_name(const char* name) {
1688   Node* root = Compile::current()->root();
1689   find_nodes_by_name(root, name);
1690 }
1691 
1692 // call from debugger: find node with name pattern in old graph
1693 // name can contain "*" in match pattern to match any characters
1694 // the matching is case insensitive
1695 void find_old_nodes_by_name(const char* name) {
1696   Node* root = old_root();
1697   find_nodes_by_name(root, name);
1698 }
1699 
1700 // call from debugger: find node with dump pattern in new/current graph
1701 // can contain "*" in match pattern to match any characters
1702 // the matching is case insensitive
1703 void find_nodes_by_dump(const char* pattern) {
1704   Node* root = Compile::current()->root();
1705   find_nodes_by_dump(root, pattern);
1706 }
1707 
1708 // call from debugger: find node with name pattern in old graph
1709 // can contain "*" in match pattern to match any characters
1710 // the matching is case insensitive
1711 void find_old_nodes_by_dump(const char* pattern) {
1712   Node* root = old_root();
1713   find_nodes_by_dump(root, pattern);
1714 }
1715 
1716 // Call this from debugger, search in same graph as n:
1717 Node* find_node(Node* n, const int idx) {
1718   return n->find(idx);
1719 }
1720 
1721 // Call this from debugger, search in new nodes:
1722 Node* find_node(const int idx) {
1723   return Compile::current()->root()->find(idx);
1724 }
1725 
1726 // Call this from debugger, search in old nodes:
1727 Node* find_old_node(const int idx) {
1728   Node* root = old_root();
1729   return (root == nullptr) ? nullptr : root->find(idx);
1730 }
1731 
1732 // Call this from debugger, search in same graph as n:
1733 Node* find_ctrl(Node* n, const int idx) {
1734   return n->find_ctrl(idx);
1735 }
1736 
1737 // Call this from debugger, search in new nodes:
1738 Node* find_ctrl(const int idx) {
1739   return Compile::current()->root()->find_ctrl(idx);
1740 }
1741 
1742 // Call this from debugger, search in old nodes:
1743 Node* find_old_ctrl(const int idx) {
1744   Node* root = old_root();
1745   return (root == nullptr) ? nullptr : root->find_ctrl(idx);
1746 }
1747 
1748 //------------------------------find_ctrl--------------------------------------
1749 // Find an ancestor to this node in the control history with given _idx
1750 Node* Node::find_ctrl(int idx) {
1751   return find(idx, true);
1752 }
1753 
1754 //------------------------------find-------------------------------------------
1755 // Tries to find the node with the index |idx| starting from this node. If idx is negative,
1756 // the search also includes forward (out) edges. Returns NULL if not found.
1757 // If only_ctrl is set, the search will only be done on control nodes. Returns NULL if
1758 // not found or if the node to be found is not a control node (search will not find it).
1759 Node* Node::find(const int idx, bool only_ctrl) {
1760   ResourceMark rm;
1761   return find_node_by_idx(this, abs(idx), (idx < 0), only_ctrl);
1762 }
1763 
1764 class PrintBFS {
1765 public:
1766   PrintBFS(const Node* start, const int max_distance, const Node* target, const char* options)
1767   : _start(start), _max_distance(max_distance), _target(target), _options(options),
1768     _dcc(this), _info_uid(cmpkey, hashkey) {}
1769 
1770   void run();
1771 private:
1772   // pipeline steps
1773   bool configure();
1774   void collect();
1775   void select();
1776   void select_all();
1777   void select_all_paths();
1778   void select_shortest_path();
1779   void sort();
1780   void print();
1781 
1782   // inputs
1783   const Node* _start;
1784   const int _max_distance;
1785   const Node* _target;
1786   const char* _options;
1787 
1788   // options
1789   bool _traverse_inputs = false;
1790   bool _traverse_outputs = false;
1791   struct Filter {
1792     bool _control = false;
1793     bool _memory = false;
1794     bool _data = false;
1795     bool _mixed = false;
1796     bool _other = false;
1797     bool is_empty() const {
1798       return !(_control || _memory || _data || _mixed || _other);
1799     }
1800     void set_all() {
1801       _control = true;
1802       _memory = true;
1803       _data = true;
1804       _mixed = true;
1805       _other = true;
1806     }
1807     // Check if the filter accepts the node. Go by the type categories, but also all CFG nodes
1808     // are considered to have control.
1809     bool accepts(const Node* n) {
1810       const Type* t = n->bottom_type();
1811       return ( _data    &&  t->has_category(Type::Category::Data)                    ) ||
1812              ( _memory  &&  t->has_category(Type::Category::Memory)                  ) ||
1813              ( _mixed   &&  t->has_category(Type::Category::Mixed)                   ) ||
1814              ( _control && (t->has_category(Type::Category::Control) || n->is_CFG()) ) ||
1815              ( _other   &&  t->has_category(Type::Category::Other)                   );
1816     }
1817   };
1818   Filter _filter_visit;
1819   Filter _filter_boundary;
1820   bool _sort_idx = false;
1821   bool _all_paths = false;
1822   bool _use_color = false;
1823   bool _print_blocks = false;
1824   bool _print_old = false;
1825   bool _dump_only = false;
1826   static void print_options_help(bool print_examples);
1827   bool parse_options();
1828 
1829 public:
1830   class DumpConfigColored : public Node::DumpConfig {
1831   public:
1832     DumpConfigColored(PrintBFS* bfs) : _bfs(bfs) {};
1833     virtual void pre_dump(outputStream* st, const Node* n);
1834     virtual void post_dump(outputStream* st);
1835   private:
1836     PrintBFS* _bfs;
1837   };
1838 private:
1839   DumpConfigColored _dcc;
1840 
1841   // node info
1842   static Node* old_node(const Node* n); // mach node -> prior IR node
1843   static void print_node_idx(const Node* n); // to tty
1844   static void print_block_id(const Block* b); // to tty
1845   static void print_node_block(const Node* n); // to tty: _pre_order, head idx, _idom, _dom_depth
1846 
1847   // traversal data structures
1848   GrowableArray<const Node*> _worklist; // BFS queue
1849   void maybe_traverse(const Node* src, const Node* dst);
1850 
1851   // node info annotation
1852   class Info {
1853   public:
1854     Info() : Info(nullptr, 0) {};
1855     Info(const Node* node, int distance)
1856       : _node(node), _distance_from_start(distance) {};
1857     const Node* node() const { return _node; };
1858     int distance() const { return _distance_from_start; };
1859     int distance_from_target() const { return _distance_from_target; }
1860     void set_distance_from_target(int d) { _distance_from_target = d; }
1861     GrowableArray<const Node*> edge_bwd; // pointing toward _start
1862     bool is_marked() const { return _mark; } // marked to keep during select
1863     void set_mark() { _mark = true; }
1864   private:
1865     const Node* _node;
1866     int _distance_from_start; // distance from _start
1867     int _distance_from_target = 0; // distance from _target if _all_paths
1868     bool _mark = false;
1869   };
1870   Dict _info_uid;            // Node -> uid
1871   GrowableArray<Info> _info; // uid  -> info
1872 
1873   Info* find_info(const Node* n) {
1874     size_t uid = (size_t)_info_uid[n];
1875     if (uid == 0) {
1876       return nullptr;
1877     }
1878     return &_info.at((int)uid);
1879   }
1880 
1881   void make_info(const Node* node, const int distance) {
1882     assert(find_info(node) == nullptr, "node does not yet have info");
1883     size_t uid = _info.length() + 1;
1884     _info_uid.Insert((void*)node, (void*)uid);
1885     _info.at_put_grow((int)uid, Info(node, distance));
1886     assert(find_info(node)->node() == node, "stored correct node");
1887   };
1888 
1889   // filled by sort, printed by print
1890   GrowableArray<const Node*> _print_list;
1891 
1892   // print header + node table
1893   void print_header() const;
1894   void print_node(const Node* n);
1895 };
1896 
1897 void PrintBFS::run() {
1898   if (!configure()) {
1899     return;
1900   }
1901   collect();
1902   select();
1903   sort();
1904   print();
1905 }
1906 
1907 // set up configuration for BFS and print
1908 bool PrintBFS::configure() {
1909   if (_max_distance < 0) {
1910     tty->print("dump_bfs: max_distance must be non-negative!\n");
1911     return false;
1912   }
1913   return parse_options();
1914 }
1915 
1916 // BFS traverse according to configuration, fill worklist and info
1917 void PrintBFS::collect() {
1918   maybe_traverse(_start, _start);
1919   int pos = 0;
1920   while (pos < _worklist.length()) {
1921     const Node* n = _worklist.at(pos++); // next node to traverse
1922     Info* info = find_info(n);
1923     if (!_filter_visit.accepts(n) && n != _start) {
1924       continue; // we hit boundary, do not traverse further
1925     }
1926     if (n != _start && n->is_Root()) {
1927       continue; // traversing through root node would lead to unrelated nodes
1928     }
1929     if (_traverse_inputs && _max_distance > info->distance()) {
1930       for (uint i = 0; i < n->req(); i++) {
1931         maybe_traverse(n, n->in(i));
1932       }
1933     }
1934     if (_traverse_outputs && _max_distance > info->distance()) {
1935       for (uint i = 0; i < n->outcnt(); i++) {
1936         maybe_traverse(n, n->raw_out(i));
1937       }
1938     }
1939   }
1940 }
1941 
1942 // go through work list, mark those that we want to print
1943 void PrintBFS::select() {
1944   if (_target == nullptr ) {
1945     select_all();
1946   } else {
1947     if (find_info(_target) == nullptr) {
1948       tty->print("Could not find target in BFS.\n");
1949       return;
1950     }
1951     if (_all_paths) {
1952       select_all_paths();
1953     } else {
1954       select_shortest_path();
1955     }
1956   }
1957 }
1958 
1959 // take all nodes from BFS
1960 void PrintBFS::select_all() {
1961   for (int i = 0; i < _worklist.length(); i++) {
1962     const Node* n = _worklist.at(i);
1963     Info* info = find_info(n);
1964     info->set_mark();
1965   }
1966 }
1967 
1968 // traverse backward from target, along edges found in BFS
1969 void PrintBFS::select_all_paths() {
1970   int pos = 0;
1971   GrowableArray<const Node*> backtrace;
1972   // start from target
1973   backtrace.push(_target);
1974   find_info(_target)->set_mark();
1975   // traverse backward
1976   while (pos < backtrace.length()) {
1977     const Node* n = backtrace.at(pos++);
1978     Info* info = find_info(n);
1979     for (int i = 0; i < info->edge_bwd.length(); i++) {
1980       // all backward edges
1981       const Node* back = info->edge_bwd.at(i);
1982       Info* back_info = find_info(back);
1983       if (!back_info->is_marked()) {
1984         // not yet found this on way back.
1985         back_info->set_distance_from_target(info->distance_from_target() + 1);
1986         if (back_info->distance_from_target() + back_info->distance() <= _max_distance) {
1987           // total distance is small enough
1988           back_info->set_mark();
1989           backtrace.push(back);
1990         }
1991       }
1992     }
1993   }
1994 }
1995 
1996 void PrintBFS::select_shortest_path() {
1997   const Node* current = _target;
1998   while (true) {
1999     Info* info = find_info(current);
2000     info->set_mark();
2001     if (current == _start) {
2002       break;
2003     }
2004     // first edge -> leads us one step closer to _start
2005     current = info->edge_bwd.at(0);
2006   }
2007 }
2008 
2009 // go through worklist in desired order, put the marked ones in print list
2010 void PrintBFS::sort() {
2011   if (_traverse_inputs && !_traverse_outputs) {
2012     // reverse order
2013     for (int i = _worklist.length() - 1; i >= 0; i--) {
2014       const Node* n = _worklist.at(i);
2015       Info* info = find_info(n);
2016       if (info->is_marked()) {
2017         _print_list.push(n);
2018       }
2019     }
2020   } else {
2021     // same order as worklist
2022     for (int i = 0; i < _worklist.length(); i++) {
2023       const Node* n = _worklist.at(i);
2024       Info* info = find_info(n);
2025       if (info->is_marked()) {
2026         _print_list.push(n);
2027       }
2028     }
2029   }
2030   if (_sort_idx) {
2031     _print_list.sort(node_idx_cmp);
2032   }
2033 }
2034 
2035 // go through printlist and print
2036 void PrintBFS::print() {
2037   if (_print_list.length() > 0 ) {
2038     print_header();
2039     for (int i = 0; i < _print_list.length(); i++) {
2040       const Node* n = _print_list.at(i);
2041       print_node(n);
2042     }
2043   } else {
2044     tty->print("No nodes to print.\n");
2045   }
2046 }
2047 
2048 void PrintBFS::print_options_help(bool print_examples) {
2049   tty->print("Usage: node->dump_bfs(int max_distance, Node* target, char* options)\n");
2050   tty->print("\n");
2051   tty->print("Use cases:\n");
2052   tty->print("  BFS traversal: no target required\n");
2053   tty->print("  shortest path: set target\n");
2054   tty->print("  all paths: set target and put 'A' in options\n");
2055   tty->print("  detect loop: subcase of all paths, have start==target\n");
2056   tty->print("\n");
2057   tty->print("Arguments:\n");
2058   tty->print("  this/start: staring point of BFS\n");
2059   tty->print("  target:\n");
2060   tty->print("    if nullptr: simple BFS\n");
2061   tty->print("    else: shortest path or all paths between this/start and target\n");
2062   tty->print("  options:\n");
2063   tty->print("    if nullptr: same as \"cdmox@B\"\n");
2064   tty->print("    else: use combination of following characters\n");
2065   tty->print("      h: display this help info\n");
2066   tty->print("      H: display this help info, with examples\n");
2067   tty->print("      +: traverse in-edges (on if neither + nor -)\n");
2068   tty->print("      -: traverse out-edges\n");
2069   tty->print("      c: visit control nodes\n");
2070   tty->print("      d: visit data nodes\n");
2071   tty->print("      m: visit memory nodes\n");
2072   tty->print("      o: visit other nodes\n");
2073   tty->print("      x: visit mixed nodes\n");
2074   tty->print("      C: boundary control nodes\n");
2075   tty->print("      D: boundary data nodes\n");
2076   tty->print("      M: boundary memory nodes\n");
2077   tty->print("      O: boundary other nodes\n");
2078   tty->print("      X: boundary mixed nodes\n");
2079   tty->print("      #: display node category in color (not supported in all terminals)\n");
2080   tty->print("      S: sort displayed nodes by node idx\n");
2081   tty->print("      A: all paths (not just shortest path to target)\n");
2082   tty->print("      @: print old nodes - before matching (if available)\n");
2083   tty->print("      B: print scheduling blocks (if available)\n");
2084   tty->print("      $: dump only, no header, no other columns\n");
2085   tty->print("\n");
2086   tty->print("recursively follow edges to nodes with permitted visit types,\n");
2087   tty->print("on the boundary additionally display nodes allowed in boundary types\n");
2088   tty->print("Note: the categories can be overlapping. For example a mixed node\n");
2089   tty->print("      can contain control and memory output. Some from the other\n");
2090   tty->print("      category are also control (Halt, Return, etc).\n");
2091   tty->print("\n");
2092   tty->print("output columns:\n");
2093   tty->print("  dist:  BFS distance to this/start\n");
2094   tty->print("  apd:   all paths distance (d_start + d_target)\n");
2095   tty->print("  block: block identifier, based on _pre_order\n");
2096   tty->print("  head:  first node in block\n");
2097   tty->print("  idom:  head node of idom block\n");
2098   tty->print("  depth: depth of block (_dom_depth)\n");
2099   tty->print("  old:   old IR node - before matching\n");
2100   tty->print("  dump:  node->dump()\n");
2101   tty->print("\n");
2102   tty->print("Note: if none of the \"cmdxo\" characters are in the options string\n");
2103   tty->print("      then we set all of them.\n");
2104   tty->print("      This allows for short strings like \"#\" for colored input traversal\n");
2105   tty->print("      or \"-#\" for colored output traversal.\n");
2106   if (print_examples) {
2107     tty->print("\n");
2108     tty->print("Examples:\n");
2109     tty->print("  if->dump_bfs(10, 0, \"+cxo\")\n");
2110     tty->print("    starting at some if node, traverse inputs recursively\n");
2111     tty->print("    only along control (mixed and other can also be control)\n");
2112     tty->print("  phi->dump_bfs(5, 0, \"-dxo\")\n");
2113     tty->print("    starting at phi node, traverse outputs recursively\n");
2114     tty->print("    only along data (mixed and other can also have data flow)\n");
2115     tty->print("  find_node(385)->dump_bfs(3, 0, \"cdmox+#@B\")\n");
2116     tty->print("    find inputs of node 385, up to 3 nodes up (+)\n");
2117     tty->print("    traverse all nodes (cdmox), use colors (#)\n");
2118     tty->print("    display old nodes and blocks, if they exist\n");
2119     tty->print("    useful call to start with\n");
2120     tty->print("  find_node(102)->dump_bfs(10, 0, \"dCDMOX-\")\n");
2121     tty->print("    find non-data dependencies of a data node\n");
2122     tty->print("    follow data node outputs until we find another category\n");
2123     tty->print("    node as the boundary\n");
2124     tty->print("  x->dump_bfs(10, y, 0)\n");
2125     tty->print("    find shortest path from x to y, along any edge or node\n");
2126     tty->print("    will not find a path if it is longer than 10\n");
2127     tty->print("    useful to find how x and y are related\n");
2128     tty->print("  find_node(741)->dump_bfs(20, find_node(746), \"c+\")\n");
2129     tty->print("    find shortest control path between two nodes\n");
2130     tty->print("  find_node(741)->dump_bfs(8, find_node(746), \"cdmox+A\")\n");
2131     tty->print("    find all paths (A) between two nodes of length at most 8\n");
2132     tty->print("  find_node(741)->dump_bfs(7, find_node(741), \"c+A\")\n");
2133     tty->print("    find all control loops for this node\n");
2134   }
2135 }
2136 
2137 bool PrintBFS::parse_options() {
2138   if (_options == nullptr) {
2139     _options = "cdmox@B"; // default options
2140   }
2141   size_t len = strlen(_options);
2142   for (size_t i = 0; i < len; i++) {
2143     switch (_options[i]) {
2144       case '+':
2145         _traverse_inputs = true;
2146         break;
2147       case '-':
2148         _traverse_outputs = true;
2149         break;
2150       case 'c':
2151         _filter_visit._control = true;
2152         break;
2153       case 'm':
2154         _filter_visit._memory = true;
2155         break;
2156       case 'd':
2157         _filter_visit._data = true;
2158         break;
2159       case 'x':
2160         _filter_visit._mixed = true;
2161         break;
2162       case 'o':
2163         _filter_visit._other = true;
2164         break;
2165       case 'C':
2166         _filter_boundary._control = true;
2167         break;
2168       case 'M':
2169         _filter_boundary._memory = true;
2170         break;
2171       case 'D':
2172         _filter_boundary._data = true;
2173         break;
2174       case 'X':
2175         _filter_boundary._mixed = true;
2176         break;
2177       case 'O':
2178         _filter_boundary._other = true;
2179         break;
2180       case 'S':
2181         _sort_idx = true;
2182         break;
2183       case 'A':
2184         _all_paths = true;
2185         break;
2186       case '#':
2187         _use_color = true;
2188         break;
2189       case 'B':
2190         _print_blocks = true;
2191         break;
2192       case '@':
2193         _print_old = true;
2194         break;
2195       case '$':
2196         _dump_only = true;
2197         break;
2198       case 'h':
2199         print_options_help(false);
2200         return false;
2201        case 'H':
2202         print_options_help(true);
2203         return false;
2204       default:
2205         tty->print_cr("dump_bfs: Unrecognized option \'%c\'", _options[i]);
2206         tty->print_cr("for help, run: find_node(0)->dump_bfs(0,0,\"H\")");
2207         return false;
2208     }
2209   }
2210   if (!_traverse_inputs && !_traverse_outputs) {
2211     _traverse_inputs = true;
2212   }
2213   if (_filter_visit.is_empty()) {
2214     _filter_visit.set_all();
2215   }
2216   Compile* C = Compile::current();
2217   _print_old &= (C->matcher() != nullptr); // only show old if there are new
2218   _print_blocks &= (C->cfg() != nullptr); // only show blocks if available
2219   return true;
2220 }
2221 
2222 void PrintBFS::DumpConfigColored::pre_dump(outputStream* st, const Node* n) {
2223   if (!_bfs->_use_color) {
2224     return;
2225   }
2226   Info* info = _bfs->find_info(n);
2227   if (info == nullptr || !info->is_marked()) {
2228     return;
2229   }
2230 
2231   const Type* t = n->bottom_type();
2232   switch (t->category()) {
2233     case Type::Category::Data:
2234       st->print("\u001b[34m");
2235       break;
2236     case Type::Category::Memory:
2237       st->print("\u001b[32m");
2238       break;
2239     case Type::Category::Mixed:
2240       st->print("\u001b[35m");
2241       break;
2242     case Type::Category::Control:
2243       st->print("\u001b[31m");
2244       break;
2245     case Type::Category::Other:
2246       st->print("\u001b[33m");
2247       break;
2248     case Type::Category::Undef:
2249       n->dump();
2250       assert(false, "category undef ??");
2251       break;
2252     default:
2253       n->dump();
2254       assert(false, "not covered");
2255       break;
2256   }
2257 }
2258 
2259 void PrintBFS::DumpConfigColored::post_dump(outputStream* st) {
2260   if (!_bfs->_use_color) {
2261     return;
2262   }
2263   st->print("\u001b[0m"); // white
2264 }
2265 
2266 Node* PrintBFS::old_node(const Node* n) {
2267   Compile* C = Compile::current();
2268   if (C->matcher() == nullptr || !C->node_arena()->contains(n)) {
2269     return (Node*)nullptr;
2270   } else {
2271     return C->matcher()->find_old_node(n);
2272   }
2273 }
2274 
2275 void PrintBFS::print_node_idx(const Node* n) {
2276   Compile* C = Compile::current();
2277   char buf[30];
2278   if (n == nullptr) {
2279     sprintf(buf,"_");           // null
2280   } else if (C->node_arena()->contains(n)) {
2281     sprintf(buf, "%d", n->_idx);  // new node
2282   } else {
2283     sprintf(buf, "o%d", n->_idx); // old node
2284   }
2285   tty->print("%6s", buf);
2286 }
2287 
2288 void PrintBFS::print_block_id(const Block* b) {
2289   Compile* C = Compile::current();
2290   char buf[30];
2291   sprintf(buf, "B%d", b->_pre_order);
2292   tty->print("%7s", buf);
2293 }
2294 
2295 void PrintBFS::print_node_block(const Node* n) {
2296   Compile* C = Compile::current();
2297   Block* b = C->node_arena()->contains(n)
2298              ? C->cfg()->get_block_for_node(n)
2299              : nullptr; // guard against old nodes
2300   if (b == nullptr) {
2301     tty->print("      _"); // Block
2302     tty->print("     _");  // head
2303     tty->print("     _");  // idom
2304     tty->print("      _"); // depth
2305   } else {
2306     print_block_id(b);
2307     print_node_idx(b->head());
2308     if (b->_idom) {
2309       print_node_idx(b->_idom->head());
2310     } else {
2311       tty->print("     _"); // idom
2312     }
2313     tty->print("%6d ", b->_dom_depth);
2314   }
2315 }
2316 
2317 // filter, and add to worklist, add info, note traversal edges
2318 void PrintBFS::maybe_traverse(const Node* src, const Node* dst) {
2319   if (dst != nullptr &&
2320      (_filter_visit.accepts(dst) ||
2321       _filter_boundary.accepts(dst) ||
2322       dst == _start)) { // correct category or start?
2323     if (find_info(dst) == nullptr) {
2324       // never visited - set up info
2325       _worklist.push(dst);
2326       int d = 0;
2327       if (dst != _start) {
2328         d = find_info(src)->distance() + 1;
2329       }
2330       make_info(dst, d);
2331     }
2332     if (src != dst) {
2333       // traversal edges useful during select
2334       find_info(dst)->edge_bwd.push(src);
2335     }
2336   }
2337 }
2338 
2339 void PrintBFS::print_header() const {
2340   if (_dump_only) {
2341     return; // no header in dump only mode
2342   }
2343   tty->print("dist");                         // distance
2344   if (_all_paths) {
2345     tty->print(" apd");                       // all paths distance
2346   }
2347   if (_print_blocks) {
2348     tty->print(" [block  head  idom depth]"); // block
2349   }
2350   if (_print_old) {
2351     tty->print("   old");                     // old node
2352   }
2353   tty->print(" dump\n");                      // node dump
2354   tty->print("---------------------------------------------\n");
2355 }
2356 
2357 void PrintBFS::print_node(const Node* n) {
2358   if (_dump_only) {
2359     n->dump("\n", false, tty, &_dcc);
2360     return;
2361   }
2362   tty->print("%4d", find_info(n)->distance());// distance
2363   if (_all_paths) {
2364     Info* info = find_info(n);
2365     int apd = info->distance() + info->distance_from_target();
2366     tty->print("%4d", apd);                   // all paths distance
2367   }
2368   if (_print_blocks) {
2369     print_node_block(n);                      // block
2370   }
2371   if (_print_old) {
2372     print_node_idx(old_node(n));              // old node
2373   }
2374   tty->print(" ");
2375   n->dump("\n", false, tty, &_dcc);           // node dump
2376 }
2377 
2378 //------------------------------dump_bfs--------------------------------------
2379 // Call this from debugger
2380 // Useful for BFS traversal, shortest path, all path, loop detection, etc
2381 // Designed to be more readable, and provide additional info
2382 // To find all options, run:
2383 //   find_node(0)->dump_bfs(0,0,"H")
2384 void Node::dump_bfs(const int max_distance, Node* target, const char* options) const {
2385   PrintBFS bfs(this, max_distance, target, options);
2386   bfs.run();
2387 }
2388 
2389 // Call this from debugger, with default arguments
2390 void Node::dump_bfs(const int max_distance) const {
2391   dump_bfs(max_distance, nullptr, nullptr);
2392 }
2393 
2394 // -----------------------------dump_idx---------------------------------------
2395 void Node::dump_idx(bool align, outputStream* st, DumpConfig* dc) const {
2396   if (dc != nullptr) {
2397     dc->pre_dump(st, this);
2398   }
2399   Compile* C = Compile::current();
2400   bool is_new = C->node_arena()->contains(this);
2401   if (align) { // print prefix empty spaces$
2402     // +1 for leading digit, +1 for "o"
2403     uint max_width = static_cast<uint>(log10(static_cast<double>(C->unique()))) + 2;
2404     // +1 for leading digit, maybe +1 for "o"
2405     uint width = static_cast<uint>(log10(static_cast<double>(_idx))) + 1 + (is_new ? 0 : 1);
2406     while (max_width > width) {
2407       st->print(" ");
2408       width++;
2409     }
2410   }
2411   if (!is_new) {
2412     st->print("o");
2413   }
2414   st->print("%d", _idx);
2415   if (dc != nullptr) {
2416     dc->post_dump(st);
2417   }
2418 }
2419 
2420 // -----------------------------dump_name--------------------------------------
2421 void Node::dump_name(outputStream* st, DumpConfig* dc) const {
2422   if (dc != nullptr) {
2423     dc->pre_dump(st, this);
2424   }
2425   st->print("%s", Name());
2426   if (dc != nullptr) {
2427     dc->post_dump(st);
2428   }
2429 }
2430 
2431 // -----------------------------Name-------------------------------------------
2432 extern const char *NodeClassNames[];
2433 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
2434 
2435 static bool is_disconnected(const Node* n) {
2436   for (uint i = 0; i < n->req(); i++) {
2437     if (n->in(i) != NULL)  return false;
2438   }
2439   return true;
2440 }
2441 
2442 #ifdef ASSERT
2443 void Node::dump_orig(outputStream *st, bool print_key) const {
2444   Compile* C = Compile::current();
2445   Node* orig = _debug_orig;
2446   if (not_a_node(orig)) orig = NULL;
2447   if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
2448   if (orig == NULL) return;
2449   if (print_key) {
2450     st->print(" !orig=");
2451   }
2452   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
2453   if (not_a_node(fast)) fast = NULL;
2454   while (orig != NULL) {
2455     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
2456     if (discon) st->print("[");
2457     if (!Compile::current()->node_arena()->contains(orig))
2458       st->print("o");
2459     st->print("%d", orig->_idx);
2460     if (discon) st->print("]");
2461     orig = orig->debug_orig();
2462     if (not_a_node(orig)) orig = NULL;
2463     if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
2464     if (orig != NULL) st->print(",");
2465     if (fast != NULL) {
2466       // Step fast twice for each single step of orig:
2467       fast = fast->debug_orig();
2468       if (not_a_node(fast)) fast = NULL;
2469       if (fast != NULL && fast != orig) {
2470         fast = fast->debug_orig();
2471         if (not_a_node(fast)) fast = NULL;
2472       }
2473       if (fast == orig) {
2474         st->print("...");
2475         break;
2476       }
2477     }
2478   }
2479 }
2480 
2481 void Node::set_debug_orig(Node* orig) {
2482   _debug_orig = orig;
2483   if (BreakAtNode == 0)  return;
2484   if (not_a_node(orig))  orig = NULL;
2485   int trip = 10;
2486   while (orig != NULL) {
2487     if (orig->debug_idx() == BreakAtNode || (int)orig->_idx == BreakAtNode) {
2488       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d orig._idx=%d orig._debug_idx=%d",
2489                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
2490       BREAKPOINT;
2491     }
2492     orig = orig->debug_orig();
2493     if (not_a_node(orig))  orig = NULL;
2494     if (trip-- <= 0)  break;
2495   }
2496 }
2497 #endif //ASSERT
2498 
2499 //------------------------------dump------------------------------------------
2500 // Dump a Node
2501 void Node::dump(const char* suffix, bool mark, outputStream* st, DumpConfig* dc) const {
2502   Compile* C = Compile::current();
2503   bool is_new = C->node_arena()->contains(this);
2504   C->_in_dump_cnt++;
2505 
2506   // idx mark name ===
2507   dump_idx(true, st, dc);
2508   st->print(mark ? " >" : "  ");
2509   dump_name(st, dc);
2510   st->print("  === ");
2511 
2512   // Dump the required and precedence inputs
2513   dump_req(st, dc);
2514   dump_prec(st, dc);
2515   // Dump the outputs
2516   dump_out(st, dc);
2517 
2518   if (is_disconnected(this)) {
2519 #ifdef ASSERT
2520     st->print("  [%d]",debug_idx());
2521     dump_orig(st);
2522 #endif
2523     st->cr();
2524     C->_in_dump_cnt--;
2525     return;                     // don't process dead nodes
2526   }
2527 
2528   if (C->clone_map().value(_idx) != 0) {
2529     C->clone_map().dump(_idx);
2530   }
2531   // Dump node-specific info
2532   dump_spec(st);
2533 #ifdef ASSERT
2534   // Dump the non-reset _debug_idx
2535   if (Verbose && WizardMode) {
2536     st->print("  [%d]",debug_idx());
2537   }
2538 #endif
2539 
2540   const Type *t = bottom_type();
2541 
2542   if (t != NULL && (t->isa_instptr() || t->isa_instklassptr())) {
2543     const TypeInstPtr  *toop = t->isa_instptr();
2544     const TypeInstKlassPtr *tkls = t->isa_instklassptr();
2545     if (toop) {
2546       st->print("  Oop:");
2547     } else if (tkls) {
2548       st->print("  Klass:");
2549     }
2550     t->dump_on(st);
2551   } else if (t == Type::MEMORY) {
2552     st->print("  Memory:");
2553     MemNode::dump_adr_type(this, adr_type(), st);
2554   } else if (Verbose || WizardMode) {
2555     st->print("  Type:");
2556     if (t) {
2557       t->dump_on(st);
2558     } else {
2559       st->print("no type");
2560     }
2561   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
2562     // Dump MachSpillcopy vector type.
2563     t->dump_on(st);
2564   }
2565   if (is_new) {
2566     DEBUG_ONLY(dump_orig(st));
2567     Node_Notes* nn = C->node_notes_at(_idx);
2568     if (nn != NULL && !nn->is_clear()) {
2569       if (nn->jvms() != NULL) {
2570         st->print(" !jvms:");
2571         nn->jvms()->dump_spec(st);
2572       }
2573     }
2574   }
2575   if (suffix) st->print("%s", suffix);
2576   C->_in_dump_cnt--;
2577 }
2578 
2579 // call from debugger: dump node to tty with newline
2580 void Node::dump() const {
2581   dump("\n");
2582 }
2583 
2584 //------------------------------dump_req--------------------------------------
2585 void Node::dump_req(outputStream* st, DumpConfig* dc) const {
2586   // Dump the required input edges
2587   for (uint i = 0; i < req(); i++) {    // For all required inputs
2588     Node* d = in(i);
2589     if (d == NULL) {
2590       st->print("_ ");
2591     } else if (not_a_node(d)) {
2592       st->print("not_a_node ");  // uninitialized, sentinel, garbage, etc.
2593     } else {
2594       d->dump_idx(false, st, dc);
2595       st->print(" ");
2596     }
2597   }
2598 }
2599 
2600 
2601 //------------------------------dump_prec-------------------------------------
2602 void Node::dump_prec(outputStream* st, DumpConfig* dc) const {
2603   // Dump the precedence edges
2604   int any_prec = 0;
2605   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
2606     Node* p = in(i);
2607     if (p != NULL) {
2608       if (!any_prec++) st->print(" |");
2609       if (not_a_node(p)) { st->print("not_a_node "); continue; }
2610       p->dump_idx(false, st, dc);
2611       st->print(" ");
2612     }
2613   }
2614 }
2615 
2616 //------------------------------dump_out--------------------------------------
2617 void Node::dump_out(outputStream* st, DumpConfig* dc) const {
2618   // Delimit the output edges
2619   st->print(" [[ ");
2620   // Dump the output edges
2621   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
2622     Node* u = _out[i];
2623     if (u == NULL) {
2624       st->print("_ ");
2625     } else if (not_a_node(u)) {
2626       st->print("not_a_node ");
2627     } else {
2628       u->dump_idx(false, st, dc);
2629       st->print(" ");
2630     }
2631   }
2632   st->print("]] ");
2633 }
2634 
2635 //------------------------------dump-------------------------------------------
2636 // call from debugger: dump Node's inputs (or outputs if d negative)
2637 void Node::dump(int d) const {
2638   dump_bfs(abs(d), nullptr, (d > 0) ? "+$" : "-$");
2639 }
2640 
2641 //------------------------------dump_ctrl--------------------------------------
2642 // call from debugger: dump Node's control inputs (or outputs if d negative)
2643 void Node::dump_ctrl(int d) const {
2644   dump_bfs(abs(d), nullptr, (d > 0) ? "+$c" : "-$c");
2645 }
2646 
2647 //-----------------------------dump_compact------------------------------------
2648 void Node::dump_comp() const {
2649   this->dump_comp("\n");
2650 }
2651 
2652 //-----------------------------dump_compact------------------------------------
2653 // Dump a Node in compact representation, i.e., just print its name and index.
2654 // Nodes can specify additional specifics to print in compact representation by
2655 // implementing dump_compact_spec.
2656 void Node::dump_comp(const char* suffix, outputStream *st) const {
2657   Compile* C = Compile::current();
2658   C->_in_dump_cnt++;
2659   st->print("%s(%d)", Name(), _idx);
2660   this->dump_compact_spec(st);
2661   if (suffix) {
2662     st->print("%s", suffix);
2663   }
2664   C->_in_dump_cnt--;
2665 }
2666 
2667 // VERIFICATION CODE
2668 // Verify all nodes if verify_depth is negative
2669 void Node::verify(int verify_depth, VectorSet& visited, Node_List& worklist) {
2670   assert(verify_depth != 0, "depth should not be 0");
2671   Compile* C = Compile::current();
2672   uint last_index_on_current_depth = worklist.size() - 1;
2673   verify_depth--; // Visiting the first node on depth 1
2674   // Only add nodes to worklist if verify_depth is negative (visit all nodes) or greater than 0
2675   bool add_to_worklist = verify_depth != 0;
2676 
2677   for (uint list_index = 0; list_index < worklist.size(); list_index++) {
2678     Node* n = worklist[list_index];
2679 
2680     if (n->is_Con() && n->bottom_type() == Type::TOP) {
2681       if (C->cached_top_node() == NULL) {
2682         C->set_cached_top_node((Node*)n);
2683       }
2684       assert(C->cached_top_node() == n, "TOP node must be unique");
2685     }
2686 
2687     uint in_len = n->len();
2688     for (uint i = 0; i < in_len; i++) {
2689       Node* x = n->_in[i];
2690       if (!x || x->is_top()) {
2691         continue;
2692       }
2693 
2694       // Verify my input has a def-use edge to me
2695       // Count use-def edges from n to x
2696       int cnt = 1;
2697       for (uint j = 0; j < i; j++) {
2698         if (n->_in[j] == x) {
2699           cnt++;
2700           break;
2701         }
2702       }
2703       if (cnt == 2) {
2704         // x is already checked as n's previous input, skip its duplicated def-use count checking
2705         continue;
2706       }
2707       for (uint j = i + 1; j < in_len; j++) {
2708         if (n->_in[j] == x) {
2709           cnt++;
2710         }
2711       }
2712 
2713       // Count def-use edges from x to n
2714       uint max = x->_outcnt;
2715       for (uint k = 0; k < max; k++) {
2716         if (x->_out[k] == n) {
2717           cnt--;
2718         }
2719       }
2720       assert(cnt == 0, "mismatched def-use edge counts");
2721 
2722       if (add_to_worklist && !visited.test_set(x->_idx)) {
2723         worklist.push(x);
2724       }
2725     }
2726 
2727     if (verify_depth > 0 && list_index == last_index_on_current_depth) {
2728       // All nodes on this depth were processed and its inputs are on the worklist. Decrement verify_depth and
2729       // store the current last list index which is the last node in the list with the new depth. All nodes
2730       // added afterwards will have a new depth again. Stop adding new nodes if depth limit is reached (=0).
2731       verify_depth--;
2732       if (verify_depth == 0) {
2733         add_to_worklist = false;
2734       }
2735       last_index_on_current_depth = worklist.size() - 1;
2736     }
2737   }
2738 }
2739 #endif // not PRODUCT
2740 
2741 //------------------------------Registers--------------------------------------
2742 // Do we Match on this edge index or not?  Generally false for Control
2743 // and true for everything else.  Weird for calls & returns.
2744 uint Node::match_edge(uint idx) const {
2745   return idx;                   // True for other than index 0 (control)
2746 }
2747 
2748 // Register classes are defined for specific machines
2749 const RegMask &Node::out_RegMask() const {
2750   ShouldNotCallThis();
2751   return RegMask::Empty;
2752 }
2753 
2754 const RegMask &Node::in_RegMask(uint) const {
2755   ShouldNotCallThis();
2756   return RegMask::Empty;
2757 }
2758 
2759 void Node_Array::grow(uint i) {
2760   assert(_max > 0, "invariant");
2761   uint old = _max;
2762   _max = next_power_of_2(i);
2763   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2764   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2765 }
2766 
2767 void Node_Array::insert(uint i, Node* n) {
2768   if (_nodes[_max - 1]) {
2769     grow(_max);
2770   }
2771   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i + 1], ((_max - i - 1) * sizeof(Node*)));
2772   _nodes[i] = n;
2773 }
2774 
2775 void Node_Array::remove(uint i) {
2776   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i + 1], (HeapWord*)&_nodes[i], ((_max - i - 1) * sizeof(Node*)));
2777   _nodes[_max - 1] = NULL;
2778 }
2779 
2780 void Node_Array::dump() const {
2781 #ifndef PRODUCT
2782   for (uint i = 0; i < _max; i++) {
2783     Node* nn = _nodes[i];
2784     if (nn != NULL) {
2785       tty->print("%5d--> ",i); nn->dump();
2786     }
2787   }
2788 #endif
2789 }
2790 
2791 //--------------------------is_iteratively_computed------------------------------
2792 // Operation appears to be iteratively computed (such as an induction variable)
2793 // It is possible for this operation to return false for a loop-varying
2794 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2795 bool Node::is_iteratively_computed() {
2796   if (ideal_reg()) { // does operation have a result register?
2797     for (uint i = 1; i < req(); i++) {
2798       Node* n = in(i);
2799       if (n != NULL && n->is_Phi()) {
2800         for (uint j = 1; j < n->req(); j++) {
2801           if (n->in(j) == this) {
2802             return true;
2803           }
2804         }
2805       }
2806     }
2807   }
2808   return false;
2809 }
2810 
2811 //--------------------------find_similar------------------------------
2812 // Return a node with opcode "opc" and same inputs as "this" if one can
2813 // be found; Otherwise return NULL;
2814 Node* Node::find_similar(int opc) {
2815   if (req() >= 2) {
2816     Node* def = in(1);
2817     if (def && def->outcnt() >= 2) {
2818       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2819         Node* use = def->fast_out(i);
2820         if (use != this &&
2821             use->Opcode() == opc &&
2822             use->req() == req()) {
2823           uint j;
2824           for (j = 0; j < use->req(); j++) {
2825             if (use->in(j) != in(j)) {
2826               break;
2827             }
2828           }
2829           if (j == use->req()) {
2830             return use;
2831           }
2832         }
2833       }
2834     }
2835   }
2836   return NULL;
2837 }
2838 
2839 
2840 //--------------------------unique_ctrl_out_or_null-------------------------
2841 // Return the unique control out if only one. Null if none or more than one.
2842 Node* Node::unique_ctrl_out_or_null() const {
2843   Node* found = NULL;
2844   for (uint i = 0; i < outcnt(); i++) {
2845     Node* use = raw_out(i);
2846     if (use->is_CFG() && use != this) {
2847       if (found != NULL) {
2848         return NULL;
2849       }
2850       found = use;
2851     }
2852   }
2853   return found;
2854 }
2855 
2856 //--------------------------unique_ctrl_out------------------------------
2857 // Return the unique control out. Asserts if none or more than one control out.
2858 Node* Node::unique_ctrl_out() const {
2859   Node* ctrl = unique_ctrl_out_or_null();
2860   assert(ctrl != NULL, "control out is assumed to be unique");
2861   return ctrl;
2862 }
2863 
2864 void Node::ensure_control_or_add_prec(Node* c) {
2865   if (in(0) == NULL) {
2866     set_req(0, c);
2867   } else if (in(0) != c) {
2868     add_prec(c);
2869   }
2870 }
2871 
2872 bool Node::is_dead_loop_safe() const {
2873   if (is_Phi()) {
2874     return true;
2875   }
2876   if (is_Proj() && in(0) == NULL)  {
2877     return true;
2878   }
2879   if ((_flags & (Flag_is_dead_loop_safe | Flag_is_Con)) != 0) {
2880     if (!is_Proj()) {
2881       return true;
2882     }
2883     if (in(0)->is_Allocate()) {
2884       return false;
2885     }
2886     // MemNode::can_see_stored_value() peeks through the boxing call
2887     if (in(0)->is_CallStaticJava() && in(0)->as_CallStaticJava()->is_boxing_method()) {
2888       return false;
2889     }
2890     return true;
2891   }
2892   return false;
2893 }
2894 
2895 //=============================================================================
2896 //------------------------------yank-------------------------------------------
2897 // Find and remove
2898 void Node_List::yank( Node *n ) {
2899   uint i;
2900   for (i = 0; i < _cnt; i++) {
2901     if (_nodes[i] == n) {
2902       break;
2903     }
2904   }
2905 
2906   if (i < _cnt) {
2907     _nodes[i] = _nodes[--_cnt];
2908   }
2909 }
2910 
2911 //------------------------------dump-------------------------------------------
2912 void Node_List::dump() const {
2913 #ifndef PRODUCT
2914   for (uint i = 0; i < _cnt; i++) {
2915     if (_nodes[i]) {
2916       tty->print("%5d--> ", i);
2917       _nodes[i]->dump();
2918     }
2919   }
2920 #endif
2921 }
2922 
2923 void Node_List::dump_simple() const {
2924 #ifndef PRODUCT
2925   for (uint i = 0; i < _cnt; i++) {
2926     if( _nodes[i] ) {
2927       tty->print(" %d", _nodes[i]->_idx);
2928     } else {
2929       tty->print(" NULL");
2930     }
2931   }
2932 #endif
2933 }
2934 
2935 //=============================================================================
2936 //------------------------------remove-----------------------------------------
2937 void Unique_Node_List::remove(Node* n) {
2938   if (_in_worklist.test(n->_idx)) {
2939     for (uint i = 0; i < size(); i++) {
2940       if (_nodes[i] == n) {
2941         map(i, Node_List::pop());
2942         _in_worklist.remove(n->_idx);
2943         return;
2944       }
2945     }
2946     ShouldNotReachHere();
2947   }
2948 }
2949 
2950 //-----------------------remove_useless_nodes----------------------------------
2951 // Remove useless nodes from worklist
2952 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2953   for (uint i = 0; i < size(); ++i) {
2954     Node *n = at(i);
2955     assert( n != NULL, "Did not expect null entries in worklist");
2956     if (!useful.test(n->_idx)) {
2957       _in_worklist.remove(n->_idx);
2958       map(i, Node_List::pop());
2959       --i;  // Visit popped node
2960       // If it was last entry, loop terminates since size() was also reduced
2961     }
2962   }
2963 }
2964 
2965 //=============================================================================
2966 void Node_Stack::grow() {
2967   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2968   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2969   size_t max = old_max << 1;             // max * 2
2970   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2971   _inode_max = _inodes + max;
2972   _inode_top = _inodes + old_top;        // restore _top
2973 }
2974 
2975 // Node_Stack is used to map nodes.
2976 Node* Node_Stack::find(uint idx) const {
2977   uint sz = size();
2978   for (uint i = 0; i < sz; i++) {
2979     if (idx == index_at(i)) {
2980       return node_at(i);
2981     }
2982   }
2983   return NULL;
2984 }
2985 
2986 //=============================================================================
2987 uint TypeNode::size_of() const { return sizeof(*this); }
2988 #ifndef PRODUCT
2989 void TypeNode::dump_spec(outputStream *st) const {
2990   if (!Verbose && !WizardMode) {
2991     // standard dump does this in Verbose and WizardMode
2992     st->print(" #"); _type->dump_on(st);
2993   }
2994 }
2995 
2996 void TypeNode::dump_compact_spec(outputStream *st) const {
2997   st->print("#");
2998   _type->dump_on(st);
2999 }
3000 #endif
3001 uint TypeNode::hash() const {
3002   return Node::hash() + _type->hash();
3003 }
3004 bool TypeNode::cmp(const Node& n) const {
3005   return !Type::cmp(_type, ((TypeNode&)n)._type);
3006 }
3007 const Type* TypeNode::bottom_type() const { return _type; }
3008 const Type* TypeNode::Value(PhaseGVN* phase) const { return _type; }
3009 
3010 //------------------------------ideal_reg--------------------------------------
3011 uint TypeNode::ideal_reg() const {
3012   return _type->ideal_reg();
3013 }