1 /*
   2  * Copyright (c) 1997, 2014, 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 "libadt/vectset.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "opto/cfgnode.hpp"
  29 #include "opto/connode.hpp"
  30 #include "opto/loopnode.hpp"
  31 #include "opto/machnode.hpp"
  32 #include "opto/matcher.hpp"
  33 #include "opto/node.hpp"
  34 #include "opto/opcodes.hpp"
  35 #include "opto/regmask.hpp"
  36 #include "opto/type.hpp"
  37 #include "utilities/copy.hpp"
  38 
  39 class RegMask;
  40 // #include "phase.hpp"
  41 class PhaseTransform;
  42 class PhaseGVN;
  43 
  44 // Arena we are currently building Nodes in
  45 const uint Node::NotAMachineReg = 0xffff0000;
  46 
  47 #ifndef PRODUCT
  48 extern int nodes_created;
  49 #endif
  50 
  51 #ifdef ASSERT
  52 
  53 //-------------------------- construct_node------------------------------------
  54 // Set a breakpoint here to identify where a particular node index is built.
  55 void Node::verify_construction() {
  56   _debug_orig = NULL;
  57   int old_debug_idx = Compile::debug_idx();
  58   int new_debug_idx = old_debug_idx+1;
  59   if (new_debug_idx > 0) {
  60     // Arrange that the lowest five decimal digits of _debug_idx
  61     // will repeat those of _idx. In case this is somehow pathological,
  62     // we continue to assign negative numbers (!) consecutively.
  63     const int mod = 100000;
  64     int bump = (int)(_idx - new_debug_idx) % mod;
  65     if (bump < 0)  bump += mod;
  66     assert(bump >= 0 && bump < mod, "");
  67     new_debug_idx += bump;
  68   }
  69   Compile::set_debug_idx(new_debug_idx);
  70   set_debug_idx( new_debug_idx );
  71   assert(Compile::current()->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  72   assert(Compile::current()->live_nodes() < Compile::current()->max_node_limit(), "Live Node limit exceeded limit");
  73   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (int)_idx == BreakAtNode)) {
  74     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d", _idx, _debug_idx);
  75     BREAKPOINT;
  76   }
  77 #if OPTO_DU_ITERATOR_ASSERT
  78   _last_del = NULL;
  79   _del_tick = 0;
  80 #endif
  81   _hash_lock = 0;
  82 }
  83 
  84 
  85 // #ifdef ASSERT ...
  86 
  87 #if OPTO_DU_ITERATOR_ASSERT
  88 void DUIterator_Common::sample(const Node* node) {
  89   _vdui     = VerifyDUIterators;
  90   _node     = node;
  91   _outcnt   = node->_outcnt;
  92   _del_tick = node->_del_tick;
  93   _last     = NULL;
  94 }
  95 
  96 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
  97   assert(_node     == node, "consistent iterator source");
  98   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
  99 }
 100 
 101 void DUIterator_Common::verify_resync() {
 102   // Ensure that the loop body has just deleted the last guy produced.
 103   const Node* node = _node;
 104   // Ensure that at least one copy of the last-seen edge was deleted.
 105   // Note:  It is OK to delete multiple copies of the last-seen edge.
 106   // Unfortunately, we have no way to verify that all the deletions delete
 107   // that same edge.  On this point we must use the Honor System.
 108   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 109   assert(node->_last_del == _last, "must have deleted the edge just produced");
 110   // We liked this deletion, so accept the resulting outcnt and tick.
 111   _outcnt   = node->_outcnt;
 112   _del_tick = node->_del_tick;
 113 }
 114 
 115 void DUIterator_Common::reset(const DUIterator_Common& that) {
 116   if (this == &that)  return;  // ignore assignment to self
 117   if (!_vdui) {
 118     // We need to initialize everything, overwriting garbage values.
 119     _last = that._last;
 120     _vdui = that._vdui;
 121   }
 122   // Note:  It is legal (though odd) for an iterator over some node x
 123   // to be reassigned to iterate over another node y.  Some doubly-nested
 124   // progress loops depend on being able to do this.
 125   const Node* node = that._node;
 126   // Re-initialize everything, except _last.
 127   _node     = node;
 128   _outcnt   = node->_outcnt;
 129   _del_tick = node->_del_tick;
 130 }
 131 
 132 void DUIterator::sample(const Node* node) {
 133   DUIterator_Common::sample(node);      // Initialize the assertion data.
 134   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 135 }
 136 
 137 void DUIterator::verify(const Node* node, bool at_end_ok) {
 138   DUIterator_Common::verify(node, at_end_ok);
 139   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 140 }
 141 
 142 void DUIterator::verify_increment() {
 143   if (_refresh_tick & 1) {
 144     // We have refreshed the index during this loop.
 145     // Fix up _idx to meet asserts.
 146     if (_idx > _outcnt)  _idx = _outcnt;
 147   }
 148   verify(_node, true);
 149 }
 150 
 151 void DUIterator::verify_resync() {
 152   // Note:  We do not assert on _outcnt, because insertions are OK here.
 153   DUIterator_Common::verify_resync();
 154   // Make sure we are still in sync, possibly with no more out-edges:
 155   verify(_node, true);
 156 }
 157 
 158 void DUIterator::reset(const DUIterator& that) {
 159   if (this == &that)  return;  // self assignment is always a no-op
 160   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 161   assert(that._idx          == 0, "assign only the result of Node::outs()");
 162   assert(_idx               == that._idx, "already assigned _idx");
 163   if (!_vdui) {
 164     // We need to initialize everything, overwriting garbage values.
 165     sample(that._node);
 166   } else {
 167     DUIterator_Common::reset(that);
 168     if (_refresh_tick & 1) {
 169       _refresh_tick++;                  // Clear the "was refreshed" flag.
 170     }
 171     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 172   }
 173 }
 174 
 175 void DUIterator::refresh() {
 176   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 177   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 178 }
 179 
 180 void DUIterator::verify_finish() {
 181   // If the loop has killed the node, do not require it to re-run.
 182   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 183   // If this assert triggers, it means that a loop used refresh_out_pos
 184   // to re-synch an iteration index, but the loop did not correctly
 185   // re-run itself, using a "while (progress)" construct.
 186   // This iterator enforces the rule that you must keep trying the loop
 187   // until it "runs clean" without any need for refreshing.
 188   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 189 }
 190 
 191 
 192 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 193   DUIterator_Common::verify(node, at_end_ok);
 194   Node** out    = node->_out;
 195   uint   cnt    = node->_outcnt;
 196   assert(cnt == _outcnt, "no insertions allowed");
 197   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 198   // This last check is carefully designed to work for NO_OUT_ARRAY.
 199 }
 200 
 201 void DUIterator_Fast::verify_limit() {
 202   const Node* node = _node;
 203   verify(node, true);
 204   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 205 }
 206 
 207 void DUIterator_Fast::verify_resync() {
 208   const Node* node = _node;
 209   if (_outp == node->_out + _outcnt) {
 210     // Note that the limit imax, not the pointer i, gets updated with the
 211     // exact count of deletions.  (For the pointer it's always "--i".)
 212     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 213     // This is a limit pointer, with a name like "imax".
 214     // Fudge the _last field so that the common assert will be happy.
 215     _last = (Node*) node->_last_del;
 216     DUIterator_Common::verify_resync();
 217   } else {
 218     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 219     // A normal internal pointer.
 220     DUIterator_Common::verify_resync();
 221     // Make sure we are still in sync, possibly with no more out-edges:
 222     verify(node, true);
 223   }
 224 }
 225 
 226 void DUIterator_Fast::verify_relimit(uint n) {
 227   const Node* node = _node;
 228   assert((int)n > 0, "use imax -= n only with a positive count");
 229   // This must be a limit pointer, with a name like "imax".
 230   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 231   // The reported number of deletions must match what the node saw.
 232   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 233   // Fudge the _last field so that the common assert will be happy.
 234   _last = (Node*) node->_last_del;
 235   DUIterator_Common::verify_resync();
 236 }
 237 
 238 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 239   assert(_outp              == that._outp, "already assigned _outp");
 240   DUIterator_Common::reset(that);
 241 }
 242 
 243 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 244   // at_end_ok means the _outp is allowed to underflow by 1
 245   _outp += at_end_ok;
 246   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 247   _outp -= at_end_ok;
 248   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 249 }
 250 
 251 void DUIterator_Last::verify_limit() {
 252   // Do not require the limit address to be resynched.
 253   //verify(node, true);
 254   assert(_outp == _node->_out, "limit still correct");
 255 }
 256 
 257 void DUIterator_Last::verify_step(uint num_edges) {
 258   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 259   _outcnt   -= num_edges;
 260   _del_tick += num_edges;
 261   // Make sure we are still in sync, possibly with no more out-edges:
 262   const Node* node = _node;
 263   verify(node, true);
 264   assert(node->_last_del == _last, "must have deleted the edge just produced");
 265 }
 266 
 267 #endif //OPTO_DU_ITERATOR_ASSERT
 268 
 269 
 270 #endif //ASSERT
 271 
 272 
 273 // This constant used to initialize _out may be any non-null value.
 274 // The value NULL is reserved for the top node only.
 275 #define NO_OUT_ARRAY ((Node**)-1)
 276 
 277 // This funny expression handshakes with Node::operator new
 278 // to pull Compile::current out of the new node's _out field,
 279 // and then calls a subroutine which manages most field
 280 // initializations.  The only one which is tricky is the
 281 // _idx field, which is const, and so must be initialized
 282 // by a return value, not an assignment.
 283 //
 284 // (Aren't you thankful that Java finals don't require so many tricks?)
 285 #define IDX_INIT(req) this->Init((req), (Compile*) this->_out)
 286 #ifdef _MSC_VER // the IDX_INIT hack falls foul of warning C4355
 287 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
 288 #endif
 289 #ifdef __clang__
 290 #pragma clang diagnostic push
 291 #pragma GCC diagnostic ignored "-Wuninitialized"
 292 #endif
 293 
 294 // Out-of-line code from node constructors.
 295 // Executed only when extra debug info. is being passed around.
 296 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 297   C->set_node_notes_at(idx, nn);
 298 }
 299 
 300 // Shared initialization code.
 301 inline int Node::Init(int req, Compile* C) {
 302   assert(Compile::current() == C, "must use operator new(Compile*)");
 303   int idx = C->next_unique();
 304 
 305   // Allocate memory for the necessary number of edges.
 306   if (req > 0) {
 307     // Allocate space for _in array to have double alignment.
 308     _in = (Node **) ((char *) (C->node_arena()->Amalloc_D(req * sizeof(void*))));
 309 #ifdef ASSERT
 310     _in[req-1] = this; // magic cookie for assertion check
 311 #endif
 312   }
 313   // If there are default notes floating around, capture them:
 314   Node_Notes* nn = C->default_node_notes();
 315   if (nn != NULL)  init_node_notes(C, idx, nn);
 316 
 317   // Note:  At this point, C is dead,
 318   // and we begin to initialize the new Node.
 319 
 320   _cnt = _max = req;
 321   _outcnt = _outmax = 0;
 322   _class_id = Class_Node;
 323   _flags = 0;
 324   _out = NO_OUT_ARRAY;
 325   return idx;
 326 }
 327 
 328 //------------------------------Node-------------------------------------------
 329 // Create a Node, with a given number of required edges.
 330 Node::Node(uint req)
 331   : _idx(IDX_INIT(req))
 332 #ifdef ASSERT
 333   , _parse_idx(_idx)
 334 #endif
 335 {
 336   assert( req < Compile::current()->max_node_limit() - NodeLimitFudgeFactor, "Input limit exceeded" );
 337   debug_only( verify_construction() );
 338   NOT_PRODUCT(nodes_created++);
 339   if (req == 0) {
 340     assert( _in == (Node**)this, "Must not pass arg count to 'new'" );
 341     _in = NULL;
 342   } else {
 343     assert( _in[req-1] == this, "Must pass arg count to 'new'" );
 344     Node** to = _in;
 345     for(uint i = 0; i < req; i++) {
 346       to[i] = NULL;
 347     }
 348   }
 349 }
 350 
 351 //------------------------------Node-------------------------------------------
 352 Node::Node(Node *n0)
 353   : _idx(IDX_INIT(1))
 354 #ifdef ASSERT
 355   , _parse_idx(_idx)
 356 #endif
 357 {
 358   debug_only( verify_construction() );
 359   NOT_PRODUCT(nodes_created++);
 360   // Assert we allocated space for input array already
 361   assert( _in[0] == this, "Must pass arg count to 'new'" );
 362   assert( is_not_dead(n0), "can not use dead node");
 363   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 364 }
 365 
 366 //------------------------------Node-------------------------------------------
 367 Node::Node(Node *n0, Node *n1)
 368   : _idx(IDX_INIT(2))
 369 #ifdef ASSERT
 370   , _parse_idx(_idx)
 371 #endif
 372 {
 373   debug_only( verify_construction() );
 374   NOT_PRODUCT(nodes_created++);
 375   // Assert we allocated space for input array already
 376   assert( _in[1] == this, "Must pass arg count to 'new'" );
 377   assert( is_not_dead(n0), "can not use dead node");
 378   assert( is_not_dead(n1), "can not use dead node");
 379   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 380   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 381 }
 382 
 383 //------------------------------Node-------------------------------------------
 384 Node::Node(Node *n0, Node *n1, Node *n2)
 385   : _idx(IDX_INIT(3))
 386 #ifdef ASSERT
 387   , _parse_idx(_idx)
 388 #endif
 389 {
 390   debug_only( verify_construction() );
 391   NOT_PRODUCT(nodes_created++);
 392   // Assert we allocated space for input array already
 393   assert( _in[2] == this, "Must pass arg count to 'new'" );
 394   assert( is_not_dead(n0), "can not use dead node");
 395   assert( is_not_dead(n1), "can not use dead node");
 396   assert( is_not_dead(n2), "can not use dead node");
 397   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 398   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 399   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 400 }
 401 
 402 //------------------------------Node-------------------------------------------
 403 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 404   : _idx(IDX_INIT(4))
 405 #ifdef ASSERT
 406   , _parse_idx(_idx)
 407 #endif
 408 {
 409   debug_only( verify_construction() );
 410   NOT_PRODUCT(nodes_created++);
 411   // Assert we allocated space for input array already
 412   assert( _in[3] == this, "Must pass arg count to 'new'" );
 413   assert( is_not_dead(n0), "can not use dead node");
 414   assert( is_not_dead(n1), "can not use dead node");
 415   assert( is_not_dead(n2), "can not use dead node");
 416   assert( is_not_dead(n3), "can not use dead node");
 417   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 418   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 419   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 420   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 421 }
 422 
 423 //------------------------------Node-------------------------------------------
 424 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 425   : _idx(IDX_INIT(5))
 426 #ifdef ASSERT
 427   , _parse_idx(_idx)
 428 #endif
 429 {
 430   debug_only( verify_construction() );
 431   NOT_PRODUCT(nodes_created++);
 432   // Assert we allocated space for input array already
 433   assert( _in[4] == this, "Must pass arg count to 'new'" );
 434   assert( is_not_dead(n0), "can not use dead node");
 435   assert( is_not_dead(n1), "can not use dead node");
 436   assert( is_not_dead(n2), "can not use dead node");
 437   assert( is_not_dead(n3), "can not use dead node");
 438   assert( is_not_dead(n4), "can not use dead node");
 439   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 440   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 441   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 442   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 443   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 444 }
 445 
 446 //------------------------------Node-------------------------------------------
 447 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 448                      Node *n4, Node *n5)
 449   : _idx(IDX_INIT(6))
 450 #ifdef ASSERT
 451   , _parse_idx(_idx)
 452 #endif
 453 {
 454   debug_only( verify_construction() );
 455   NOT_PRODUCT(nodes_created++);
 456   // Assert we allocated space for input array already
 457   assert( _in[5] == this, "Must pass arg count to 'new'" );
 458   assert( is_not_dead(n0), "can not use dead node");
 459   assert( is_not_dead(n1), "can not use dead node");
 460   assert( is_not_dead(n2), "can not use dead node");
 461   assert( is_not_dead(n3), "can not use dead node");
 462   assert( is_not_dead(n4), "can not use dead node");
 463   assert( is_not_dead(n5), "can not use dead node");
 464   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 465   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 466   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 467   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 468   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 469   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 470 }
 471 
 472 //------------------------------Node-------------------------------------------
 473 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 474                      Node *n4, Node *n5, Node *n6)
 475   : _idx(IDX_INIT(7))
 476 #ifdef ASSERT
 477   , _parse_idx(_idx)
 478 #endif
 479 {
 480   debug_only( verify_construction() );
 481   NOT_PRODUCT(nodes_created++);
 482   // Assert we allocated space for input array already
 483   assert( _in[6] == this, "Must pass arg count to 'new'" );
 484   assert( is_not_dead(n0), "can not use dead node");
 485   assert( is_not_dead(n1), "can not use dead node");
 486   assert( is_not_dead(n2), "can not use dead node");
 487   assert( is_not_dead(n3), "can not use dead node");
 488   assert( is_not_dead(n4), "can not use dead node");
 489   assert( is_not_dead(n5), "can not use dead node");
 490   assert( is_not_dead(n6), "can not use dead node");
 491   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 492   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 493   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 494   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 495   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 496   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 497   _in[6] = n6; if (n6 != NULL) n6->add_out((Node *)this);
 498 }
 499 
 500 #ifdef __clang__
 501 #pragma clang diagnostic pop
 502 #endif
 503 
 504 
 505 //------------------------------clone------------------------------------------
 506 // Clone a Node.
 507 Node *Node::clone() const {
 508   Compile* C = Compile::current();
 509   uint s = size_of();           // Size of inherited Node
 510   Node *n = (Node*)C->node_arena()->Amalloc_D(size_of() + _max*sizeof(Node*));
 511   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 512   // Set the new input pointer array
 513   n->_in = (Node**)(((char*)n)+s);
 514   // Cannot share the old output pointer array, so kill it
 515   n->_out = NO_OUT_ARRAY;
 516   // And reset the counters to 0
 517   n->_outcnt = 0;
 518   n->_outmax = 0;
 519   // Unlock this guy, since he is not in any hash table.
 520   debug_only(n->_hash_lock = 0);
 521   // Walk the old node's input list to duplicate its edges
 522   uint i;
 523   for( i = 0; i < len(); i++ ) {
 524     Node *x = in(i);
 525     n->_in[i] = x;
 526     if (x != NULL) x->add_out(n);
 527   }
 528   if (is_macro())
 529     C->add_macro_node(n);
 530   if (is_expensive())
 531     C->add_expensive_node(n);
 532   // If the cloned node is a range check dependent CastII, add it to the list.
 533   CastIINode* cast = n->isa_CastII();
 534   if (cast != NULL && cast->has_range_check()) {
 535     C->add_range_check_cast(cast);
 536   }
 537 
 538   n->set_idx(C->next_unique()); // Get new unique index as well
 539   debug_only( n->verify_construction() );
 540   NOT_PRODUCT(nodes_created++);
 541   // Do not patch over the debug_idx of a clone, because it makes it
 542   // impossible to break on the clone's moment of creation.
 543   //debug_only( n->set_debug_idx( debug_idx() ) );
 544 
 545   C->copy_node_notes_to(n, (Node*) this);
 546 
 547   // MachNode clone
 548   uint nopnds;
 549   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 550     MachNode *mach  = n->as_Mach();
 551     MachNode *mthis = this->as_Mach();
 552     // Get address of _opnd_array.
 553     // It should be the same offset since it is the clone of this node.
 554     MachOper **from = mthis->_opnds;
 555     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 556                     pointer_delta((const void*)from,
 557                                   (const void*)(&mthis->_opnds), 1));
 558     mach->_opnds = to;
 559     for ( uint i = 0; i < nopnds; ++i ) {
 560       to[i] = from[i]->clone(C);
 561     }
 562   }
 563   // cloning CallNode may need to clone JVMState
 564   if (n->is_Call()) {
 565     n->as_Call()->clone_jvms(C);
 566   }
 567   if (n->is_SafePoint()) {
 568     n->as_SafePoint()->clone_replaced_nodes();
 569   }
 570   return n;                     // Return the clone
 571 }
 572 
 573 //---------------------------setup_is_top--------------------------------------
 574 // Call this when changing the top node, to reassert the invariants
 575 // required by Node::is_top.  See Compile::set_cached_top_node.
 576 void Node::setup_is_top() {
 577   if (this == (Node*)Compile::current()->top()) {
 578     // This node has just become top.  Kill its out array.
 579     _outcnt = _outmax = 0;
 580     _out = NULL;                           // marker value for top
 581     assert(is_top(), "must be top");
 582   } else {
 583     if (_out == NULL)  _out = NO_OUT_ARRAY;
 584     assert(!is_top(), "must not be top");
 585   }
 586 }
 587 
 588 
 589 //------------------------------~Node------------------------------------------
 590 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 591 extern int reclaim_idx ;
 592 extern int reclaim_in  ;
 593 extern int reclaim_node;
 594 void Node::destruct() {
 595   // Eagerly reclaim unique Node numberings
 596   Compile* compile = Compile::current();
 597   if ((uint)_idx+1 == compile->unique()) {
 598     compile->set_unique(compile->unique()-1);
 599 #ifdef ASSERT
 600     reclaim_idx++;
 601 #endif
 602   }
 603   // Clear debug info:
 604   Node_Notes* nn = compile->node_notes_at(_idx);
 605   if (nn != NULL)  nn->clear();
 606   // Walk the input array, freeing the corresponding output edges
 607   _cnt = _max;  // forget req/prec distinction
 608   uint i;
 609   for( i = 0; i < _max; i++ ) {
 610     set_req(i, NULL);
 611     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 612   }
 613   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 614   // See if the input array was allocated just prior to the object
 615   int edge_size = _max*sizeof(void*);
 616   int out_edge_size = _outmax*sizeof(void*);
 617   char *edge_end = ((char*)_in) + edge_size;
 618   char *out_array = (char*)(_out == NO_OUT_ARRAY? NULL: _out);
 619   char *out_edge_end = out_array + out_edge_size;
 620   int node_size = size_of();
 621 
 622   // Free the output edge array
 623   if (out_edge_size > 0) {
 624 #ifdef ASSERT
 625     if( out_edge_end == compile->node_arena()->hwm() )
 626       reclaim_in  += out_edge_size;  // count reclaimed out edges with in edges
 627 #endif
 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 #ifdef ASSERT
 634     if( edge_end+node_size == compile->node_arena()->hwm() ) {
 635       reclaim_in  += edge_size;
 636       reclaim_node+= node_size;
 637     }
 638 #else
 639     // It was; free the input array and object all in one hit
 640     compile->node_arena()->Afree(_in,edge_size+node_size);
 641 #endif
 642   } else {
 643 
 644     // Free just the input array
 645 #ifdef ASSERT
 646     if( edge_end == compile->node_arena()->hwm() )
 647       reclaim_in  += edge_size;
 648 #endif
 649     compile->node_arena()->Afree(_in,edge_size);
 650 
 651     // Free just the object
 652 #ifdef ASSERT
 653     if( ((char*)this) + node_size == compile->node_arena()->hwm() )
 654       reclaim_node+= node_size;
 655 #else
 656     compile->node_arena()->Afree(this,node_size);
 657 #endif
 658   }
 659   if (is_macro()) {
 660     compile->remove_macro_node(this);
 661   }
 662   if (is_expensive()) {
 663     compile->remove_expensive_node(this);
 664   }
 665   CastIINode* cast = isa_CastII();
 666   if (cast != NULL && cast->has_range_check()) {
 667     compile->remove_range_check_cast(cast);
 668   }
 669 
 670   if (is_SafePoint()) {
 671     as_SafePoint()->delete_replaced_nodes();
 672   }
 673 #ifdef ASSERT
 674   // We will not actually delete the storage, but we'll make the node unusable.
 675   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 676   _in = _out = (Node**) badAddress;
 677   _max = _cnt = _outmax = _outcnt = 0;
 678 #endif
 679 }
 680 
 681 //------------------------------grow-------------------------------------------
 682 // Grow the input array, making space for more edges
 683 void Node::grow( uint len ) {
 684   Arena* arena = Compile::current()->node_arena();
 685   uint new_max = _max;
 686   if( new_max == 0 ) {
 687     _max = 4;
 688     _in = (Node**)arena->Amalloc(4*sizeof(Node*));
 689     Node** to = _in;
 690     to[0] = NULL;
 691     to[1] = NULL;
 692     to[2] = NULL;
 693     to[3] = NULL;
 694     return;
 695   }
 696   while( new_max <= len ) new_max <<= 1; // Find next power-of-2
 697   // Trimming to limit allows a uint8 to handle up to 255 edges.
 698   // Previously I was using only powers-of-2 which peaked at 128 edges.
 699   //if( new_max >= limit ) new_max = limit-1;
 700   _in = (Node**)arena->Arealloc(_in, _max*sizeof(Node*), new_max*sizeof(Node*));
 701   Copy::zero_to_bytes(&_in[_max], (new_max-_max)*sizeof(Node*)); // NULL all new space
 702   _max = new_max;               // Record new max length
 703   // This assertion makes sure that Node::_max is wide enough to
 704   // represent the numerical value of new_max.
 705   assert(_max == new_max && _max > len, "int width of _max is too small");
 706 }
 707 
 708 //-----------------------------out_grow----------------------------------------
 709 // Grow the input array, making space for more edges
 710 void Node::out_grow( uint len ) {
 711   assert(!is_top(), "cannot grow a top node's out array");
 712   Arena* arena = Compile::current()->node_arena();
 713   uint new_max = _outmax;
 714   if( new_max == 0 ) {
 715     _outmax = 4;
 716     _out = (Node **)arena->Amalloc(4*sizeof(Node*));
 717     return;
 718   }
 719   while( new_max <= len ) new_max <<= 1; // Find next power-of-2
 720   // Trimming to limit allows a uint8 to handle up to 255 edges.
 721   // Previously I was using only powers-of-2 which peaked at 128 edges.
 722   //if( new_max >= limit ) new_max = limit-1;
 723   assert(_out != NULL && _out != NO_OUT_ARRAY, "out must have sensible value");
 724   _out = (Node**)arena->Arealloc(_out,_outmax*sizeof(Node*),new_max*sizeof(Node*));
 725   //Copy::zero_to_bytes(&_out[_outmax], (new_max-_outmax)*sizeof(Node*)); // NULL all new space
 726   _outmax = new_max;               // Record new max length
 727   // This assertion makes sure that Node::_max is wide enough to
 728   // represent the numerical value of new_max.
 729   assert(_outmax == new_max && _outmax > len, "int width of _outmax is too small");
 730 }
 731 
 732 #ifdef ASSERT
 733 //------------------------------is_dead----------------------------------------
 734 bool Node::is_dead() const {
 735   // Mach and pinch point nodes may look like dead.
 736   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 737     return false;
 738   for( uint i = 0; i < _max; i++ )
 739     if( _in[i] != NULL )
 740       return false;
 741   dump();
 742   return true;
 743 }
 744 #endif
 745 
 746 
 747 //------------------------------is_unreachable---------------------------------
 748 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 749   assert(!is_Mach(), "doesn't work with MachNodes");
 750   return outcnt() == 0 || igvn.type(this) == Type::TOP || in(0)->is_top();
 751 }
 752 
 753 //------------------------------add_req----------------------------------------
 754 // Add a new required input at the end
 755 void Node::add_req( Node *n ) {
 756   assert( is_not_dead(n), "can not use dead node");
 757 
 758   // Look to see if I can move precedence down one without reallocating
 759   if( (_cnt >= _max) || (in(_max-1) != NULL) )
 760     grow( _max+1 );
 761 
 762   // Find a precedence edge to move
 763   if( in(_cnt) != NULL ) {       // Next precedence edge is busy?
 764     uint i;
 765     for( i=_cnt; i<_max; i++ )
 766       if( in(i) == NULL )       // Find the NULL at end of prec edge list
 767         break;                  // There must be one, since we grew the array
 768     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 769   }
 770   _in[_cnt++] = n;            // Stuff over old prec edge
 771   if (n != NULL) n->add_out((Node *)this);
 772 }
 773 
 774 //---------------------------add_req_batch-------------------------------------
 775 // Add a new required input at the end
 776 void Node::add_req_batch( Node *n, uint m ) {
 777   assert( is_not_dead(n), "can not use dead node");
 778   // check various edge cases
 779   if ((int)m <= 1) {
 780     assert((int)m >= 0, "oob");
 781     if (m != 0)  add_req(n);
 782     return;
 783   }
 784 
 785   // Look to see if I can move precedence down one without reallocating
 786   if( (_cnt+m) > _max || _in[_max-m] )
 787     grow( _max+m );
 788 
 789   // Find a precedence edge to move
 790   if( _in[_cnt] != NULL ) {     // Next precedence edge is busy?
 791     uint i;
 792     for( i=_cnt; i<_max; i++ )
 793       if( _in[i] == NULL )      // Find the NULL at end of prec edge list
 794         break;                  // There must be one, since we grew the array
 795     // Slide all the precs over by m positions (assume #prec << m).
 796     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 797   }
 798 
 799   // Stuff over the old prec edges
 800   for(uint i=0; i<m; i++ ) {
 801     _in[_cnt++] = n;
 802   }
 803 
 804   // Insert multiple out edges on the node.
 805   if (n != NULL && !n->is_top()) {
 806     for(uint i=0; i<m; i++ ) {
 807       n->add_out((Node *)this);
 808     }
 809   }
 810 }
 811 
 812 //------------------------------del_req----------------------------------------
 813 // Delete the required edge and compact the edge array
 814 void Node::del_req( uint idx ) {
 815   assert( idx < _cnt, "oob");
 816   assert( !VerifyHashTableKeys || _hash_lock == 0,
 817           "remove node from hash table before modifying it");
 818   // First remove corresponding def-use edge
 819   Node *n = in(idx);
 820   if (n != NULL) n->del_out((Node *)this);
 821   _in[idx] = in(--_cnt);  // Compact the array
 822   _in[_cnt] = NULL;       // NULL out emptied slot
 823 }
 824 
 825 //------------------------------del_req_ordered--------------------------------
 826 // Delete the required edge and compact the edge array with preserved order
 827 void Node::del_req_ordered( uint idx ) {
 828   assert( idx < _cnt, "oob");
 829   assert( !VerifyHashTableKeys || _hash_lock == 0,
 830           "remove node from hash table before modifying it");
 831   // First remove corresponding def-use edge
 832   Node *n = in(idx);
 833   if (n != NULL) n->del_out((Node *)this);
 834   if (idx < _cnt - 1) { // Not last edge ?
 835     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx-1)*sizeof(Node*)));
 836   }
 837   _in[--_cnt] = NULL;   // NULL out emptied slot
 838 }
 839 
 840 //------------------------------ins_req----------------------------------------
 841 // Insert a new required input at the end
 842 void Node::ins_req( uint idx, Node *n ) {
 843   assert( is_not_dead(n), "can not use dead node");
 844   add_req(NULL);                // Make space
 845   assert( idx < _max, "Must have allocated enough space");
 846   // Slide over
 847   if(_cnt-idx-1 > 0) {
 848     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 849   }
 850   _in[idx] = n;                            // Stuff over old required edge
 851   if (n != NULL) n->add_out((Node *)this); // Add reciprocal def-use edge
 852 }
 853 
 854 //-----------------------------find_edge---------------------------------------
 855 int Node::find_edge(Node* n) {
 856   for (uint i = 0; i < len(); i++) {
 857     if (_in[i] == n)  return i;
 858   }
 859   return -1;
 860 }
 861 
 862 //----------------------------replace_edge-------------------------------------
 863 int Node::replace_edge(Node* old, Node* neww) {
 864   if (old == neww)  return 0;  // nothing to do
 865   uint nrep = 0;
 866   for (uint i = 0; i < len(); i++) {
 867     if (in(i) == old) {
 868       if (i < req())
 869         set_req(i, neww);
 870       else
 871         set_prec(i, neww);
 872       nrep++;
 873     }
 874   }
 875   return nrep;
 876 }
 877 
 878 /**
 879  * Replace input edges in the range pointing to 'old' node.
 880  */
 881 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end) {
 882   if (old == neww)  return 0;  // nothing to do
 883   uint nrep = 0;
 884   for (int i = start; i < end; i++) {
 885     if (in(i) == old) {
 886       set_req(i, neww);
 887       nrep++;
 888     }
 889   }
 890   return nrep;
 891 }
 892 
 893 //-------------------------disconnect_inputs-----------------------------------
 894 // NULL out all inputs to eliminate incoming Def-Use edges.
 895 // Return the number of edges between 'n' and 'this'
 896 int Node::disconnect_inputs(Node *n, Compile* C) {
 897   int edges_to_n = 0;
 898 
 899   uint cnt = req();
 900   for( uint i = 0; i < cnt; ++i ) {
 901     if( in(i) == 0 ) continue;
 902     if( in(i) == n ) ++edges_to_n;
 903     set_req(i, NULL);
 904   }
 905   // Remove precedence edges if any exist
 906   // Note: Safepoints may have precedence edges, even during parsing
 907   if( (req() != len()) && (in(req()) != NULL) ) {
 908     uint max = len();
 909     for( uint i = 0; i < max; ++i ) {
 910       if( in(i) == 0 ) continue;
 911       if( in(i) == n ) ++edges_to_n;
 912       set_prec(i, NULL);
 913     }
 914   }
 915 
 916   // Node::destruct requires all out edges be deleted first
 917   // debug_only(destruct();)   // no reuse benefit expected
 918   if (edges_to_n == 0) {
 919     C->record_dead_node(_idx);
 920   }
 921   return edges_to_n;
 922 }
 923 
 924 //-----------------------------uncast---------------------------------------
 925 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 926 // Strip away casting.  (It is depth-limited.)
 927 Node* Node::uncast() const {
 928   // Should be inline:
 929   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 930   if (is_ConstraintCast() || is_CheckCastPP())
 931     return uncast_helper(this);
 932   else
 933     return (Node*) this;
 934 }
 935 
 936 //---------------------------uncast_helper-------------------------------------
 937 Node* Node::uncast_helper(const Node* p) {
 938 #ifdef ASSERT
 939   uint depth_count = 0;
 940   const Node* orig_p = p;
 941 #endif
 942 
 943   while (true) {
 944 #ifdef ASSERT
 945     if (depth_count >= K) {
 946       orig_p->dump(4);
 947       if (p != orig_p)
 948         p->dump(1);
 949     }
 950     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
 951 #endif
 952     if (p == NULL || p->req() != 2) {
 953       break;
 954     } else if (p->is_ConstraintCast()) {
 955       p = p->in(1);
 956     } else if (p->is_CheckCastPP()) {
 957       p = p->in(1);
 958     } else {
 959       break;
 960     }
 961   }
 962   return (Node*) p;
 963 }
 964 
 965 //------------------------------add_prec---------------------------------------
 966 // Add a new precedence input.  Precedence inputs are unordered, with
 967 // duplicates removed and NULLs packed down at the end.
 968 void Node::add_prec( Node *n ) {
 969   assert( is_not_dead(n), "can not use dead node");
 970 
 971   // Check for NULL at end
 972   if( _cnt >= _max || in(_max-1) )
 973     grow( _max+1 );
 974 
 975   // Find a precedence edge to move
 976   uint i = _cnt;
 977   while( in(i) != NULL ) i++;
 978   _in[i] = n;                                // Stuff prec edge over NULL
 979   if ( n != NULL) n->add_out((Node *)this);  // Add mirror edge
 980 }
 981 
 982 //------------------------------rm_prec----------------------------------------
 983 // Remove a precedence input.  Precedence inputs are unordered, with
 984 // duplicates removed and NULLs packed down at the end.
 985 void Node::rm_prec( uint j ) {
 986 
 987   // Find end of precedence list to pack NULLs
 988   uint i;
 989   for( i=j; i<_max; i++ )
 990     if( !_in[i] )               // Find the NULL at end of prec edge list
 991       break;
 992   if (_in[j] != NULL) _in[j]->del_out((Node *)this);
 993   _in[j] = _in[--i];            // Move last element over removed guy
 994   _in[i] = NULL;                // NULL out last element
 995 }
 996 
 997 //------------------------------size_of----------------------------------------
 998 uint Node::size_of() const { return sizeof(*this); }
 999 
1000 //------------------------------ideal_reg--------------------------------------
1001 uint Node::ideal_reg() const { return 0; }
1002 
1003 //------------------------------jvms-------------------------------------------
1004 JVMState* Node::jvms() const { return NULL; }
1005 
1006 #ifdef ASSERT
1007 //------------------------------jvms-------------------------------------------
1008 bool Node::verify_jvms(const JVMState* using_jvms) const {
1009   for (JVMState* jvms = this->jvms(); jvms != NULL; jvms = jvms->caller()) {
1010     if (jvms == using_jvms)  return true;
1011   }
1012   return false;
1013 }
1014 
1015 //------------------------------init_NodeProperty------------------------------
1016 void Node::init_NodeProperty() {
1017   assert(_max_classes <= max_jushort, "too many NodeProperty classes");
1018   assert(_max_flags <= max_jushort, "too many NodeProperty flags");
1019 }
1020 #endif
1021 
1022 //------------------------------format-----------------------------------------
1023 // Print as assembly
1024 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1025 //------------------------------emit-------------------------------------------
1026 // Emit bytes starting at parameter 'ptr'.
1027 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
1028 //------------------------------size-------------------------------------------
1029 // Size of instruction in bytes
1030 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1031 
1032 //------------------------------CFG Construction-------------------------------
1033 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1034 // Goto and Return.
1035 const Node *Node::is_block_proj() const { return 0; }
1036 
1037 // Minimum guaranteed type
1038 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1039 
1040 
1041 //------------------------------raise_bottom_type------------------------------
1042 // Get the worst-case Type output for this Node.
1043 void Node::raise_bottom_type(const Type* new_type) {
1044   if (is_Type()) {
1045     TypeNode *n = this->as_Type();
1046     if (VerifyAliases) {
1047       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1048     }
1049     n->set_type(new_type);
1050   } else if (is_Load()) {
1051     LoadNode *n = this->as_Load();
1052     if (VerifyAliases) {
1053       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1054     }
1055     n->set_type(new_type);
1056   }
1057 }
1058 
1059 //------------------------------Identity---------------------------------------
1060 // Return a node that the given node is equivalent to.
1061 Node *Node::Identity( PhaseTransform * ) {
1062   return this;                  // Default to no identities
1063 }
1064 
1065 //------------------------------Value------------------------------------------
1066 // Compute a new Type for a node using the Type of the inputs.
1067 const Type *Node::Value( PhaseTransform * ) const {
1068   return bottom_type();         // Default to worst-case Type
1069 }
1070 
1071 //------------------------------Ideal------------------------------------------
1072 //
1073 // 'Idealize' the graph rooted at this Node.
1074 //
1075 // In order to be efficient and flexible there are some subtle invariants
1076 // these Ideal calls need to hold.  Running with '+VerifyIterativeGVN' checks
1077 // these invariants, although its too slow to have on by default.  If you are
1078 // hacking an Ideal call, be sure to test with +VerifyIterativeGVN!
1079 //
1080 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1081 // pointer.  If ANY change is made, it must return the root of the reshaped
1082 // graph - even if the root is the same Node.  Example: swapping the inputs
1083 // to an AddINode gives the same answer and same root, but you still have to
1084 // return the 'this' pointer instead of NULL.
1085 //
1086 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1087 // Identity call to return an old Node; basically if Identity can find
1088 // another Node have the Ideal call make no change and return NULL.
1089 // Example: AddINode::Ideal must check for add of zero; in this case it
1090 // returns NULL instead of doing any graph reshaping.
1091 //
1092 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1093 // sharing there may be other users of the old Nodes relying on their current
1094 // semantics.  Modifying them will break the other users.
1095 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1096 // "X+3" unchanged in case it is shared.
1097 //
1098 // If you modify the 'this' pointer's inputs, you should use
1099 // 'set_req'.  If you are making a new Node (either as the new root or
1100 // some new internal piece) you may use 'init_req' to set the initial
1101 // value.  You can make a new Node with either 'new' or 'clone'.  In
1102 // either case, def-use info is correctly maintained.
1103 //
1104 // Example: reshape "(X+3)+4" into "X+7":
1105 //    set_req(1, in(1)->in(1));
1106 //    set_req(2, phase->intcon(7));
1107 //    return this;
1108 // Example: reshape "X*4" into "X<<2"
1109 //    return new (C) LShiftINode(in(1), phase->intcon(2));
1110 //
1111 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1112 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1113 //    Node *shift=phase->transform(new(C)LShiftINode(in(1),phase->intcon(5)));
1114 //    return new (C) AddINode(shift, in(1));
1115 //
1116 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1117 // These forms are faster than 'phase->transform(new (C) ConNode())' and Do
1118 // The Right Thing with def-use info.
1119 //
1120 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1121 // graph uses the 'this' Node it must be the root.  If you want a Node with
1122 // the same Opcode as the 'this' pointer use 'clone'.
1123 //
1124 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1125   return NULL;                  // Default to being Ideal already
1126 }
1127 
1128 // Some nodes have specific Ideal subgraph transformations only if they are
1129 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1130 // for the transformations to happen.
1131 bool Node::has_special_unique_user() const {
1132   assert(outcnt() == 1, "match only for unique out");
1133   Node* n = unique_out();
1134   int op  = Opcode();
1135   if( this->is_Store() ) {
1136     // Condition for back-to-back stores folding.
1137     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1138   } else if (this->is_Load()) {
1139     // Condition for removing an unused LoadNode from the MemBarAcquire precedence input
1140     return n->Opcode() == Op_MemBarAcquire;
1141   } else if( op == Op_AddL ) {
1142     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1143     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1144   } else if( op == Op_SubI || op == Op_SubL ) {
1145     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1146     return n->Opcode() == op && n->in(2) == this;
1147   }
1148   return false;
1149 };
1150 
1151 //--------------------------find_exact_control---------------------------------
1152 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1153 Node* Node::find_exact_control(Node* ctrl) {
1154   if (ctrl == NULL && this->is_Region())
1155     ctrl = this->as_Region()->is_copy();
1156 
1157   if (ctrl != NULL && ctrl->is_CatchProj()) {
1158     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1159       ctrl = ctrl->in(0);
1160     if (ctrl != NULL && !ctrl->is_top())
1161       ctrl = ctrl->in(0);
1162   }
1163 
1164   if (ctrl != NULL && ctrl->is_Proj())
1165     ctrl = ctrl->in(0);
1166 
1167   return ctrl;
1168 }
1169 
1170 //--------------------------dominates------------------------------------------
1171 // Helper function for MemNode::all_controls_dominate().
1172 // Check if 'this' control node dominates or equal to 'sub' control node.
1173 // We already know that if any path back to Root or Start reaches 'this',
1174 // then all paths so, so this is a simple search for one example,
1175 // not an exhaustive search for a counterexample.
1176 bool Node::dominates(Node* sub, Node_List &nlist) {
1177   assert(this->is_CFG(), "expecting control");
1178   assert(sub != NULL && sub->is_CFG(), "expecting control");
1179 
1180   // detect dead cycle without regions
1181   int iterations_without_region_limit = DominatorSearchLimit;
1182 
1183   Node* orig_sub = sub;
1184   Node* dom      = this;
1185   bool  met_dom  = false;
1186   nlist.clear();
1187 
1188   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1189   // After seeing 'dom', continue up to Root or Start.
1190   // If we hit a region (backward split point), it may be a loop head.
1191   // Keep going through one of the region's inputs.  If we reach the
1192   // same region again, go through a different input.  Eventually we
1193   // will either exit through the loop head, or give up.
1194   // (If we get confused, break out and return a conservative 'false'.)
1195   while (sub != NULL) {
1196     if (sub->is_top())  break; // Conservative answer for dead code.
1197     if (sub == dom) {
1198       if (nlist.size() == 0) {
1199         // No Region nodes except loops were visited before and the EntryControl
1200         // path was taken for loops: it did not walk in a cycle.
1201         return true;
1202       } else if (met_dom) {
1203         break;          // already met before: walk in a cycle
1204       } else {
1205         // Region nodes were visited. Continue walk up to Start or Root
1206         // to make sure that it did not walk in a cycle.
1207         met_dom = true; // first time meet
1208         iterations_without_region_limit = DominatorSearchLimit; // Reset
1209      }
1210     }
1211     if (sub->is_Start() || sub->is_Root()) {
1212       // Success if we met 'dom' along a path to Start or Root.
1213       // We assume there are no alternative paths that avoid 'dom'.
1214       // (This assumption is up to the caller to ensure!)
1215       return met_dom;
1216     }
1217     Node* up = sub->in(0);
1218     // Normalize simple pass-through regions and projections:
1219     up = sub->find_exact_control(up);
1220     // If sub == up, we found a self-loop.  Try to push past it.
1221     if (sub == up && sub->is_Loop()) {
1222       // Take loop entry path on the way up to 'dom'.
1223       up = sub->in(1); // in(LoopNode::EntryControl);
1224     } else if (sub == up && sub->is_Region() && sub->req() != 3) {
1225       // Always take in(1) path on the way up to 'dom' for clone regions
1226       // (with only one input) or regions which merge > 2 paths
1227       // (usually used to merge fast/slow paths).
1228       up = sub->in(1);
1229     } else if (sub == up && sub->is_Region()) {
1230       // Try both paths for Regions with 2 input paths (it may be a loop head).
1231       // It could give conservative 'false' answer without information
1232       // which region's input is the entry path.
1233       iterations_without_region_limit = DominatorSearchLimit; // Reset
1234 
1235       bool region_was_visited_before = false;
1236       // Was this Region node visited before?
1237       // If so, we have reached it because we accidentally took a
1238       // loop-back edge from 'sub' back into the body of the loop,
1239       // and worked our way up again to the loop header 'sub'.
1240       // So, take the first unexplored path on the way up to 'dom'.
1241       for (int j = nlist.size() - 1; j >= 0; j--) {
1242         intptr_t ni = (intptr_t)nlist.at(j);
1243         Node* visited = (Node*)(ni & ~1);
1244         bool  visited_twice_already = ((ni & 1) != 0);
1245         if (visited == sub) {
1246           if (visited_twice_already) {
1247             // Visited 2 paths, but still stuck in loop body.  Give up.
1248             return false;
1249           }
1250           // The Region node was visited before only once.
1251           // (We will repush with the low bit set, below.)
1252           nlist.remove(j);
1253           // We will find a new edge and re-insert.
1254           region_was_visited_before = true;
1255           break;
1256         }
1257       }
1258 
1259       // Find an incoming edge which has not been seen yet; walk through it.
1260       assert(up == sub, "");
1261       uint skip = region_was_visited_before ? 1 : 0;
1262       for (uint i = 1; i < sub->req(); i++) {
1263         Node* in = sub->in(i);
1264         if (in != NULL && !in->is_top() && in != sub) {
1265           if (skip == 0) {
1266             up = in;
1267             break;
1268           }
1269           --skip;               // skip this nontrivial input
1270         }
1271       }
1272 
1273       // Set 0 bit to indicate that both paths were taken.
1274       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1275     }
1276 
1277     if (up == sub) {
1278       break;    // some kind of tight cycle
1279     }
1280     if (up == orig_sub && met_dom) {
1281       // returned back after visiting 'dom'
1282       break;    // some kind of cycle
1283     }
1284     if (--iterations_without_region_limit < 0) {
1285       break;    // dead cycle
1286     }
1287     sub = up;
1288   }
1289 
1290   // Did not meet Root or Start node in pred. chain.
1291   // Conservative answer for dead code.
1292   return false;
1293 }
1294 
1295 //------------------------------remove_dead_region-----------------------------
1296 // This control node is dead.  Follow the subgraph below it making everything
1297 // using it dead as well.  This will happen normally via the usual IterGVN
1298 // worklist but this call is more efficient.  Do not update use-def info
1299 // inside the dead region, just at the borders.
1300 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1301   // Con's are a popular node to re-hit in the hash table again.
1302   if( dead->is_Con() ) return;
1303 
1304   // Can't put ResourceMark here since igvn->_worklist uses the same arena
1305   // for verify pass with +VerifyOpto and we add/remove elements in it here.
1306   Node_List  nstack(Thread::current()->resource_area());
1307 
1308   Node *top = igvn->C->top();
1309   nstack.push(dead);
1310   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1311 
1312   while (nstack.size() > 0) {
1313     dead = nstack.pop();
1314     if (dead->outcnt() > 0) {
1315       // Keep dead node on stack until all uses are processed.
1316       nstack.push(dead);
1317       // For all Users of the Dead...    ;-)
1318       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1319         Node* use = dead->last_out(k);
1320         igvn->hash_delete(use);       // Yank from hash table prior to mod
1321         if (use->in(0) == dead) {     // Found another dead node
1322           assert (!use->is_Con(), "Control for Con node should be Root node.");
1323           use->set_req(0, top);       // Cut dead edge to prevent processing
1324           nstack.push(use);           // the dead node again.
1325         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1326                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1327                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1328           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1329           use->set_req(0, top);       // Cut self edge
1330           nstack.push(use);
1331         } else {                      // Else found a not-dead user
1332           // Dead if all inputs are top or null
1333           bool dead_use = !use->is_Root(); // Keep empty graph alive
1334           for (uint j = 1; j < use->req(); j++) {
1335             Node* in = use->in(j);
1336             if (in == dead) {         // Turn all dead inputs into TOP
1337               use->set_req(j, top);
1338             } else if (in != NULL && !in->is_top()) {
1339               dead_use = false;
1340             }
1341           }
1342           if (dead_use) {
1343             if (use->is_Region()) {
1344               use->set_req(0, top);   // Cut self edge
1345             }
1346             nstack.push(use);
1347           } else {
1348             igvn->_worklist.push(use);
1349           }
1350         }
1351         // Refresh the iterator, since any number of kills might have happened.
1352         k = dead->last_outs(kmin);
1353       }
1354     } else { // (dead->outcnt() == 0)
1355       // Done with outputs.
1356       igvn->hash_delete(dead);
1357       igvn->_worklist.remove(dead);
1358       igvn->set_type(dead, Type::TOP);
1359       if (dead->is_macro()) {
1360         igvn->C->remove_macro_node(dead);
1361       }
1362       if (dead->is_expensive()) {
1363         igvn->C->remove_expensive_node(dead);
1364       }
1365       CastIINode* cast = dead->isa_CastII();
1366       if (cast != NULL && cast->has_range_check()) {
1367         igvn->C->remove_range_check_cast(cast);
1368       }
1369       igvn->C->record_dead_node(dead->_idx);
1370       // Kill all inputs to the dead guy
1371       for (uint i=0; i < dead->req(); i++) {
1372         Node *n = dead->in(i);      // Get input to dead guy
1373         if (n != NULL && !n->is_top()) { // Input is valid?
1374           dead->set_req(i, top);    // Smash input away
1375           if (n->outcnt() == 0) {   // Input also goes dead?
1376             if (!n->is_Con())
1377               nstack.push(n);       // Clear it out as well
1378           } else if (n->outcnt() == 1 &&
1379                      n->has_special_unique_user()) {
1380             igvn->add_users_to_worklist( n );
1381           } else if (n->outcnt() <= 2 && n->is_Store()) {
1382             // Push store's uses on worklist to enable folding optimization for
1383             // store/store and store/load to the same address.
1384             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1385             // and remove_globally_dead_node().
1386             igvn->add_users_to_worklist( n );
1387           }
1388         }
1389       }
1390     } // (dead->outcnt() == 0)
1391   }   // while (nstack.size() > 0) for outputs
1392   return;
1393 }
1394 
1395 //------------------------------remove_dead_region-----------------------------
1396 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1397   Node *n = in(0);
1398   if( !n ) return false;
1399   // Lost control into this guy?  I.e., it became unreachable?
1400   // Aggressively kill all unreachable code.
1401   if (can_reshape && n->is_top()) {
1402     kill_dead_code(this, phase->is_IterGVN());
1403     return false; // Node is dead.
1404   }
1405 
1406   if( n->is_Region() && n->as_Region()->is_copy() ) {
1407     Node *m = n->nonnull_req();
1408     set_req(0, m);
1409     return true;
1410   }
1411   return false;
1412 }
1413 
1414 //------------------------------Ideal_DU_postCCP-------------------------------
1415 // Idealize graph, using DU info.  Must clone result into new-space
1416 Node *Node::Ideal_DU_postCCP( PhaseCCP * ) {
1417   return NULL;                 // Default to no change
1418 }
1419 
1420 //------------------------------hash-------------------------------------------
1421 // Hash function over Nodes.
1422 uint Node::hash() const {
1423   uint sum = 0;
1424   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1425     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded NULLs
1426   return (sum>>2) + _cnt + Opcode();
1427 }
1428 
1429 //------------------------------cmp--------------------------------------------
1430 // Compare special parts of simple Nodes
1431 uint Node::cmp( const Node &n ) const {
1432   return 1;                     // Must be same
1433 }
1434 
1435 //------------------------------rematerialize-----------------------------------
1436 // Should we clone rather than spill this instruction?
1437 bool Node::rematerialize() const {
1438   if ( is_Mach() )
1439     return this->as_Mach()->rematerialize();
1440   else
1441     return (_flags & Flag_rematerialize) != 0;
1442 }
1443 
1444 //------------------------------needs_anti_dependence_check---------------------
1445 // Nodes which use memory without consuming it, hence need antidependences.
1446 bool Node::needs_anti_dependence_check() const {
1447   if( req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0 )
1448     return false;
1449   else
1450     return in(1)->bottom_type()->has_memory();
1451 }
1452 
1453 
1454 // Get an integer constant from a ConNode (or CastIINode).
1455 // Return a default value if there is no apparent constant here.
1456 const TypeInt* Node::find_int_type() const {
1457   if (this->is_Type()) {
1458     return this->as_Type()->type()->isa_int();
1459   } else if (this->is_Con()) {
1460     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1461     return this->bottom_type()->isa_int();
1462   }
1463   return NULL;
1464 }
1465 
1466 // Get a pointer constant from a ConstNode.
1467 // Returns the constant if it is a pointer ConstNode
1468 intptr_t Node::get_ptr() const {
1469   assert( Opcode() == Op_ConP, "" );
1470   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1471 }
1472 
1473 // Get a narrow oop constant from a ConNNode.
1474 intptr_t Node::get_narrowcon() const {
1475   assert( Opcode() == Op_ConN, "" );
1476   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1477 }
1478 
1479 // Get a long constant from a ConNode.
1480 // Return a default value if there is no apparent constant here.
1481 const TypeLong* Node::find_long_type() const {
1482   if (this->is_Type()) {
1483     return this->as_Type()->type()->isa_long();
1484   } else if (this->is_Con()) {
1485     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1486     return this->bottom_type()->isa_long();
1487   }
1488   return NULL;
1489 }
1490 
1491 
1492 /**
1493  * Return a ptr type for nodes which should have it.
1494  */
1495 const TypePtr* Node::get_ptr_type() const {
1496   const TypePtr* tp = this->bottom_type()->make_ptr();
1497 #ifdef ASSERT
1498   if (tp == NULL) {
1499     this->dump(1);
1500     assert((tp != NULL), "unexpected node type");
1501   }
1502 #endif
1503   return tp;
1504 }
1505 
1506 // Get a double constant from a ConstNode.
1507 // Returns the constant if it is a double ConstNode
1508 jdouble Node::getd() const {
1509   assert( Opcode() == Op_ConD, "" );
1510   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1511 }
1512 
1513 // Get a float constant from a ConstNode.
1514 // Returns the constant if it is a float ConstNode
1515 jfloat Node::getf() const {
1516   assert( Opcode() == Op_ConF, "" );
1517   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1518 }
1519 
1520 #ifndef PRODUCT
1521 
1522 //----------------------------NotANode----------------------------------------
1523 // Used in debugging code to avoid walking across dead or uninitialized edges.
1524 static inline bool NotANode(const Node* n) {
1525   if (n == NULL)                   return true;
1526   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
1527   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
1528   return false;
1529 }
1530 
1531 
1532 //------------------------------find------------------------------------------
1533 // Find a neighbor of this Node with the given _idx
1534 // If idx is negative, find its absolute value, following both _in and _out.
1535 static void find_recur(Compile* C,  Node* &result, Node *n, int idx, bool only_ctrl,
1536                         VectorSet* old_space, VectorSet* new_space ) {
1537   int node_idx = (idx >= 0) ? idx : -idx;
1538   if (NotANode(n))  return;  // Gracefully handle NULL, -1, 0xabababab, etc.
1539   // Contained in new_space or old_space?   Check old_arena first since it's mostly empty.
1540   VectorSet *v = C->old_arena()->contains(n) ? old_space : new_space;
1541   if( v->test(n->_idx) ) return;
1542   if( (int)n->_idx == node_idx
1543       debug_only(|| n->debug_idx() == node_idx) ) {
1544     if (result != NULL)
1545       tty->print("find: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1546                  (uintptr_t)result, (uintptr_t)n, node_idx);
1547     result = n;
1548   }
1549   v->set(n->_idx);
1550   for( uint i=0; i<n->len(); i++ ) {
1551     if( only_ctrl && !(n->is_Region()) && (n->Opcode() != Op_Root) && (i != TypeFunc::Control) ) continue;
1552     find_recur(C, result, n->in(i), idx, only_ctrl, old_space, new_space );
1553   }
1554   // Search along forward edges also:
1555   if (idx < 0 && !only_ctrl) {
1556     for( uint j=0; j<n->outcnt(); j++ ) {
1557       find_recur(C, result, n->raw_out(j), idx, only_ctrl, old_space, new_space );
1558     }
1559   }
1560 #ifdef ASSERT
1561   // Search along debug_orig edges last, checking for cycles
1562   Node* orig = n->debug_orig();
1563   if (orig != NULL) {
1564     do {
1565       if (NotANode(orig))  break;
1566       find_recur(C, result, orig, idx, only_ctrl, old_space, new_space );
1567       orig = orig->debug_orig();
1568     } while (orig != NULL && orig != n->debug_orig());
1569   }
1570 #endif //ASSERT
1571 }
1572 
1573 // call this from debugger:
1574 Node* find_node(Node* n, int idx) {
1575   return n->find(idx);
1576 }
1577 
1578 //------------------------------find-------------------------------------------
1579 Node* Node::find(int idx) const {
1580   ResourceArea *area = Thread::current()->resource_area();
1581   VectorSet old_space(area), new_space(area);
1582   Node* result = NULL;
1583   find_recur(Compile::current(), result, (Node*) this, idx, false, &old_space, &new_space );
1584   return result;
1585 }
1586 
1587 //------------------------------find_ctrl--------------------------------------
1588 // Find an ancestor to this node in the control history with given _idx
1589 Node* Node::find_ctrl(int idx) const {
1590   ResourceArea *area = Thread::current()->resource_area();
1591   VectorSet old_space(area), new_space(area);
1592   Node* result = NULL;
1593   find_recur(Compile::current(), result, (Node*) this, idx, true, &old_space, &new_space );
1594   return result;
1595 }
1596 #endif
1597 
1598 
1599 
1600 #ifndef PRODUCT
1601 
1602 // -----------------------------Name-------------------------------------------
1603 extern const char *NodeClassNames[];
1604 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
1605 
1606 static bool is_disconnected(const Node* n) {
1607   for (uint i = 0; i < n->req(); i++) {
1608     if (n->in(i) != NULL)  return false;
1609   }
1610   return true;
1611 }
1612 
1613 #ifdef ASSERT
1614 static void dump_orig(Node* orig, outputStream *st) {
1615   Compile* C = Compile::current();
1616   if (NotANode(orig)) orig = NULL;
1617   if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1618   if (orig == NULL) return;
1619   st->print(" !orig=");
1620   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
1621   if (NotANode(fast)) fast = NULL;
1622   while (orig != NULL) {
1623     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
1624     if (discon) st->print("[");
1625     if (!Compile::current()->node_arena()->contains(orig))
1626       st->print("o");
1627     st->print("%d", orig->_idx);
1628     if (discon) st->print("]");
1629     orig = orig->debug_orig();
1630     if (NotANode(orig)) orig = NULL;
1631     if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1632     if (orig != NULL) st->print(",");
1633     if (fast != NULL) {
1634       // Step fast twice for each single step of orig:
1635       fast = fast->debug_orig();
1636       if (NotANode(fast)) fast = NULL;
1637       if (fast != NULL && fast != orig) {
1638         fast = fast->debug_orig();
1639         if (NotANode(fast)) fast = NULL;
1640       }
1641       if (fast == orig) {
1642         st->print("...");
1643         break;
1644       }
1645     }
1646   }
1647 }
1648 
1649 void Node::set_debug_orig(Node* orig) {
1650   _debug_orig = orig;
1651   if (BreakAtNode == 0)  return;
1652   if (NotANode(orig))  orig = NULL;
1653   int trip = 10;
1654   while (orig != NULL) {
1655     if (orig->debug_idx() == BreakAtNode || (int)orig->_idx == BreakAtNode) {
1656       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d orig._idx=%d orig._debug_idx=%d",
1657                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
1658       BREAKPOINT;
1659     }
1660     orig = orig->debug_orig();
1661     if (NotANode(orig))  orig = NULL;
1662     if (trip-- <= 0)  break;
1663   }
1664 }
1665 #endif //ASSERT
1666 
1667 //------------------------------dump------------------------------------------
1668 // Dump a Node
1669 void Node::dump(const char* suffix, outputStream *st) const {
1670   Compile* C = Compile::current();
1671   bool is_new = C->node_arena()->contains(this);
1672   C->_in_dump_cnt++;
1673   st->print("%c%d\t%s\t=== ", is_new ? ' ' : 'o', _idx, Name());
1674 
1675   // Dump the required and precedence inputs
1676   dump_req(st);
1677   dump_prec(st);
1678   // Dump the outputs
1679   dump_out(st);
1680 
1681   if (is_disconnected(this)) {
1682 #ifdef ASSERT
1683     st->print("  [%d]",debug_idx());
1684     dump_orig(debug_orig(), st);
1685 #endif
1686     st->cr();
1687     C->_in_dump_cnt--;
1688     return;                     // don't process dead nodes
1689   }
1690 
1691   // Dump node-specific info
1692   dump_spec(st);
1693 #ifdef ASSERT
1694   // Dump the non-reset _debug_idx
1695   if (Verbose && WizardMode) {
1696     st->print("  [%d]",debug_idx());
1697   }
1698 #endif
1699 
1700   const Type *t = bottom_type();
1701 
1702   if (t != NULL && (t->isa_instptr() || t->isa_klassptr())) {
1703     const TypeInstPtr  *toop = t->isa_instptr();
1704     const TypeKlassPtr *tkls = t->isa_klassptr();
1705     ciKlass*           klass = toop ? toop->klass() : (tkls ? tkls->klass() : NULL );
1706     if (klass && klass->is_loaded() && klass->is_interface()) {
1707       st->print("  Interface:");
1708     } else if (toop) {
1709       st->print("  Oop:");
1710     } else if (tkls) {
1711       st->print("  Klass:");
1712     }
1713     t->dump_on(st);
1714   } else if (t == Type::MEMORY) {
1715     st->print("  Memory:");
1716     MemNode::dump_adr_type(this, adr_type(), st);
1717   } else if (Verbose || WizardMode) {
1718     st->print("  Type:");
1719     if (t) {
1720       t->dump_on(st);
1721     } else {
1722       st->print("no type");
1723     }
1724   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
1725     // Dump MachSpillcopy vector type.
1726     t->dump_on(st);
1727   }
1728   if (is_new) {
1729     debug_only(dump_orig(debug_orig(), st));
1730     Node_Notes* nn = C->node_notes_at(_idx);
1731     if (nn != NULL && !nn->is_clear()) {
1732       if (nn->jvms() != NULL) {
1733         st->print(" !jvms:");
1734         nn->jvms()->dump_spec(st);
1735       }
1736     }
1737   }
1738   if (suffix) st->print("%s", suffix);
1739   C->_in_dump_cnt--;
1740 }
1741 
1742 //------------------------------dump_req--------------------------------------
1743 void Node::dump_req(outputStream *st) const {
1744   // Dump the required input edges
1745   for (uint i = 0; i < req(); i++) {    // For all required inputs
1746     Node* d = in(i);
1747     if (d == NULL) {
1748       st->print("_ ");
1749     } else if (NotANode(d)) {
1750       st->print("NotANode ");  // uninitialized, sentinel, garbage, etc.
1751     } else {
1752       st->print("%c%d ", Compile::current()->node_arena()->contains(d) ? ' ' : 'o', d->_idx);
1753     }
1754   }
1755 }
1756 
1757 
1758 //------------------------------dump_prec-------------------------------------
1759 void Node::dump_prec(outputStream *st) const {
1760   // Dump the precedence edges
1761   int any_prec = 0;
1762   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
1763     Node* p = in(i);
1764     if (p != NULL) {
1765       if (!any_prec++) st->print(" |");
1766       if (NotANode(p)) { st->print("NotANode "); continue; }
1767       st->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
1768     }
1769   }
1770 }
1771 
1772 //------------------------------dump_out--------------------------------------
1773 void Node::dump_out(outputStream *st) const {
1774   // Delimit the output edges
1775   st->print(" [[");
1776   // Dump the output edges
1777   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
1778     Node* u = _out[i];
1779     if (u == NULL) {
1780       st->print("_ ");
1781     } else if (NotANode(u)) {
1782       st->print("NotANode ");
1783     } else {
1784       st->print("%c%d ", Compile::current()->node_arena()->contains(u) ? ' ' : 'o', u->_idx);
1785     }
1786   }
1787   st->print("]] ");
1788 }
1789 
1790 //------------------------------dump_nodes-------------------------------------
1791 static void dump_nodes(const Node* start, int d, bool only_ctrl) {
1792   Node* s = (Node*)start; // remove const
1793   if (NotANode(s)) return;
1794 
1795   uint depth = (uint)ABS(d);
1796   int direction = d;
1797   Compile* C = Compile::current();
1798   GrowableArray <Node *> nstack(C->live_nodes());
1799 
1800   nstack.append(s);
1801   int begin = 0;
1802   int end = 0;
1803   for(uint i = 0; i < depth; i++) {
1804     end = nstack.length();
1805     for(int j = begin; j < end; j++) {
1806       Node* tp  = nstack.at(j);
1807       uint limit = direction > 0 ? tp->len() : tp->outcnt();
1808       for(uint k = 0; k < limit; k++) {
1809         Node* n = direction > 0 ? tp->in(k) : tp->raw_out(k);
1810 
1811         if (NotANode(n))  continue;
1812         // do not recurse through top or the root (would reach unrelated stuff)
1813         if (n->is_Root() || n->is_top())  continue;
1814         if (only_ctrl && !n->is_CFG()) continue;
1815 
1816         bool on_stack = nstack.contains(n);
1817         if (!on_stack) {
1818           nstack.append(n);
1819         }
1820       }
1821     }
1822     begin = end;
1823   }
1824   end = nstack.length();
1825   if (direction > 0) {
1826     for(int j = end-1; j >= 0; j--) {
1827       nstack.at(j)->dump();
1828     }
1829   } else {
1830     for(int j = 0; j < end; j++) {
1831       nstack.at(j)->dump();
1832     }
1833   }
1834 }
1835 
1836 //------------------------------dump-------------------------------------------
1837 void Node::dump(int d) const {
1838   dump_nodes(this, d, false);
1839 }
1840 
1841 //------------------------------dump_ctrl--------------------------------------
1842 // Dump a Node's control history to depth
1843 void Node::dump_ctrl(int d) const {
1844   dump_nodes(this, d, true);
1845 }
1846 
1847 // VERIFICATION CODE
1848 // For each input edge to a node (ie - for each Use-Def edge), verify that
1849 // there is a corresponding Def-Use edge.
1850 //------------------------------verify_edges-----------------------------------
1851 void Node::verify_edges(Unique_Node_List &visited) {
1852   uint i, j, idx;
1853   int  cnt;
1854   Node *n;
1855 
1856   // Recursive termination test
1857   if (visited.member(this))  return;
1858   visited.push(this);
1859 
1860   // Walk over all input edges, checking for correspondence
1861   for( i = 0; i < len(); i++ ) {
1862     n = in(i);
1863     if (n != NULL && !n->is_top()) {
1864       // Count instances of (Node *)this
1865       cnt = 0;
1866       for (idx = 0; idx < n->_outcnt; idx++ ) {
1867         if (n->_out[idx] == (Node *)this)  cnt++;
1868       }
1869       assert( cnt > 0,"Failed to find Def-Use edge." );
1870       // Check for duplicate edges
1871       // walk the input array downcounting the input edges to n
1872       for( j = 0; j < len(); j++ ) {
1873         if( in(j) == n ) cnt--;
1874       }
1875       assert( cnt == 0,"Mismatched edge count.");
1876     } else if (n == NULL) {
1877       assert(i >= req() || i == 0 || is_Region() || is_Phi(), "only regions or phis have null data edges");
1878     } else {
1879       assert(n->is_top(), "sanity");
1880       // Nothing to check.
1881     }
1882   }
1883   // Recursive walk over all input edges
1884   for( i = 0; i < len(); i++ ) {
1885     n = in(i);
1886     if( n != NULL )
1887       in(i)->verify_edges(visited);
1888   }
1889 }
1890 
1891 //------------------------------verify_recur-----------------------------------
1892 static const Node *unique_top = NULL;
1893 
1894 void Node::verify_recur(const Node *n, int verify_depth,
1895                         VectorSet &old_space, VectorSet &new_space) {
1896   if ( verify_depth == 0 )  return;
1897   if (verify_depth > 0)  --verify_depth;
1898 
1899   Compile* C = Compile::current();
1900 
1901   // Contained in new_space or old_space?
1902   VectorSet *v = C->node_arena()->contains(n) ? &new_space : &old_space;
1903   // Check for visited in the proper space.  Numberings are not unique
1904   // across spaces so we need a separate VectorSet for each space.
1905   if( v->test_set(n->_idx) ) return;
1906 
1907   if (n->is_Con() && n->bottom_type() == Type::TOP) {
1908     if (C->cached_top_node() == NULL)
1909       C->set_cached_top_node((Node*)n);
1910     assert(C->cached_top_node() == n, "TOP node must be unique");
1911   }
1912 
1913   for( uint i = 0; i < n->len(); i++ ) {
1914     Node *x = n->in(i);
1915     if (!x || x->is_top()) continue;
1916 
1917     // Verify my input has a def-use edge to me
1918     if (true /*VerifyDefUse*/) {
1919       // Count use-def edges from n to x
1920       int cnt = 0;
1921       for( uint j = 0; j < n->len(); j++ )
1922         if( n->in(j) == x )
1923           cnt++;
1924       // Count def-use edges from x to n
1925       uint max = x->_outcnt;
1926       for( uint k = 0; k < max; k++ )
1927         if (x->_out[k] == n)
1928           cnt--;
1929       assert( cnt == 0, "mismatched def-use edge counts" );
1930     }
1931 
1932     verify_recur(x, verify_depth, old_space, new_space);
1933   }
1934 
1935 }
1936 
1937 //------------------------------verify-----------------------------------------
1938 // Check Def-Use info for my subgraph
1939 void Node::verify() const {
1940   Compile* C = Compile::current();
1941   Node* old_top = C->cached_top_node();
1942   ResourceMark rm;
1943   ResourceArea *area = Thread::current()->resource_area();
1944   VectorSet old_space(area), new_space(area);
1945   verify_recur(this, -1, old_space, new_space);
1946   C->set_cached_top_node(old_top);
1947 }
1948 #endif
1949 
1950 
1951 //------------------------------walk-------------------------------------------
1952 // Graph walk, with both pre-order and post-order functions
1953 void Node::walk(NFunc pre, NFunc post, void *env) {
1954   VectorSet visited(Thread::current()->resource_area()); // Setup for local walk
1955   walk_(pre, post, env, visited);
1956 }
1957 
1958 void Node::walk_(NFunc pre, NFunc post, void *env, VectorSet &visited) {
1959   if( visited.test_set(_idx) ) return;
1960   pre(*this,env);               // Call the pre-order walk function
1961   for( uint i=0; i<_max; i++ )
1962     if( in(i) )                 // Input exists and is not walked?
1963       in(i)->walk_(pre,post,env,visited); // Walk it with pre & post functions
1964   post(*this,env);              // Call the post-order walk function
1965 }
1966 
1967 void Node::nop(Node &, void*) {}
1968 
1969 //------------------------------Registers--------------------------------------
1970 // Do we Match on this edge index or not?  Generally false for Control
1971 // and true for everything else.  Weird for calls & returns.
1972 uint Node::match_edge(uint idx) const {
1973   return idx;                   // True for other than index 0 (control)
1974 }
1975 
1976 static RegMask _not_used_at_all;
1977 // Register classes are defined for specific machines
1978 const RegMask &Node::out_RegMask() const {
1979   ShouldNotCallThis();
1980   return _not_used_at_all;
1981 }
1982 
1983 const RegMask &Node::in_RegMask(uint) const {
1984   ShouldNotCallThis();
1985   return _not_used_at_all;
1986 }
1987 
1988 //=============================================================================
1989 //-----------------------------------------------------------------------------
1990 void Node_Array::reset( Arena *new_arena ) {
1991   _a->Afree(_nodes,_max*sizeof(Node*));
1992   _max   = 0;
1993   _nodes = NULL;
1994   _a     = new_arena;
1995 }
1996 
1997 //------------------------------clear------------------------------------------
1998 // Clear all entries in _nodes to NULL but keep storage
1999 void Node_Array::clear() {
2000   Copy::zero_to_bytes( _nodes, _max*sizeof(Node*) );
2001 }
2002 
2003 //-----------------------------------------------------------------------------
2004 void Node_Array::grow( uint i ) {
2005   if( !_max ) {
2006     _max = 1;
2007     _nodes = (Node**)_a->Amalloc( _max * sizeof(Node*) );
2008     _nodes[0] = NULL;
2009   }
2010   uint old = _max;
2011   while( i >= _max ) _max <<= 1;        // Double to fit
2012   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2013   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2014 }
2015 
2016 //-----------------------------------------------------------------------------
2017 void Node_Array::insert( uint i, Node *n ) {
2018   if( _nodes[_max-1] ) grow(_max);      // Get more space if full
2019   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i+1], ((_max-i-1)*sizeof(Node*)));
2020   _nodes[i] = n;
2021 }
2022 
2023 //-----------------------------------------------------------------------------
2024 void Node_Array::remove( uint i ) {
2025   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i+1], (HeapWord*)&_nodes[i], ((_max-i-1)*sizeof(Node*)));
2026   _nodes[_max-1] = NULL;
2027 }
2028 
2029 //-----------------------------------------------------------------------------
2030 void Node_Array::sort( C_sort_func_t func) {
2031   qsort( _nodes, _max, sizeof( Node* ), func );
2032 }
2033 
2034 //-----------------------------------------------------------------------------
2035 void Node_Array::dump() const {
2036 #ifndef PRODUCT
2037   for( uint i = 0; i < _max; i++ ) {
2038     Node *nn = _nodes[i];
2039     if( nn != NULL ) {
2040       tty->print("%5d--> ",i); nn->dump();
2041     }
2042   }
2043 #endif
2044 }
2045 
2046 //--------------------------is_iteratively_computed------------------------------
2047 // Operation appears to be iteratively computed (such as an induction variable)
2048 // It is possible for this operation to return false for a loop-varying
2049 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2050 bool Node::is_iteratively_computed() {
2051   if (ideal_reg()) { // does operation have a result register?
2052     for (uint i = 1; i < req(); i++) {
2053       Node* n = in(i);
2054       if (n != NULL && n->is_Phi()) {
2055         for (uint j = 1; j < n->req(); j++) {
2056           if (n->in(j) == this) {
2057             return true;
2058           }
2059         }
2060       }
2061     }
2062   }
2063   return false;
2064 }
2065 
2066 //--------------------------find_similar------------------------------
2067 // Return a node with opcode "opc" and same inputs as "this" if one can
2068 // be found; Otherwise return NULL;
2069 Node* Node::find_similar(int opc) {
2070   if (req() >= 2) {
2071     Node* def = in(1);
2072     if (def && def->outcnt() >= 2) {
2073       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2074         Node* use = def->fast_out(i);
2075         if (use->Opcode() == opc &&
2076             use->req() == req()) {
2077           uint j;
2078           for (j = 0; j < use->req(); j++) {
2079             if (use->in(j) != in(j)) {
2080               break;
2081             }
2082           }
2083           if (j == use->req()) {
2084             return use;
2085           }
2086         }
2087       }
2088     }
2089   }
2090   return NULL;
2091 }
2092 
2093 
2094 //--------------------------unique_ctrl_out------------------------------
2095 // Return the unique control out if only one. Null if none or more than one.
2096 Node* Node::unique_ctrl_out() {
2097   Node* found = NULL;
2098   for (uint i = 0; i < outcnt(); i++) {
2099     Node* use = raw_out(i);
2100     if (use->is_CFG() && use != this) {
2101       if (found != NULL) return NULL;
2102       found = use;
2103     }
2104   }
2105   return found;
2106 }
2107 
2108 //=============================================================================
2109 //------------------------------yank-------------------------------------------
2110 // Find and remove
2111 void Node_List::yank( Node *n ) {
2112   uint i;
2113   for( i = 0; i < _cnt; i++ )
2114     if( _nodes[i] == n )
2115       break;
2116 
2117   if( i < _cnt )
2118     _nodes[i] = _nodes[--_cnt];
2119 }
2120 
2121 //------------------------------dump-------------------------------------------
2122 void Node_List::dump() const {
2123 #ifndef PRODUCT
2124   for( uint i = 0; i < _cnt; i++ )
2125     if( _nodes[i] ) {
2126       tty->print("%5d--> ",i);
2127       _nodes[i]->dump();
2128     }
2129 #endif
2130 }
2131 
2132 void Node_List::dump_simple() const {
2133 #ifndef PRODUCT
2134   for( uint i = 0; i < _cnt; i++ )
2135     if( _nodes[i] ) {
2136       tty->print(" %d", _nodes[i]->_idx);
2137     } else {
2138       tty->print(" NULL");
2139     }
2140 #endif
2141 }
2142 
2143 //=============================================================================
2144 //------------------------------remove-----------------------------------------
2145 void Unique_Node_List::remove( Node *n ) {
2146   if( _in_worklist[n->_idx] ) {
2147     for( uint i = 0; i < size(); i++ )
2148       if( _nodes[i] == n ) {
2149         map(i,Node_List::pop());
2150         _in_worklist >>= n->_idx;
2151         return;
2152       }
2153     ShouldNotReachHere();
2154   }
2155 }
2156 
2157 //-----------------------remove_useless_nodes----------------------------------
2158 // Remove useless nodes from worklist
2159 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2160 
2161   for( uint i = 0; i < size(); ++i ) {
2162     Node *n = at(i);
2163     assert( n != NULL, "Did not expect null entries in worklist");
2164     if( ! useful.test(n->_idx) ) {
2165       _in_worklist >>= n->_idx;
2166       map(i,Node_List::pop());
2167       // Node *replacement = Node_List::pop();
2168       // if( i != size() ) { // Check if removing last entry
2169       //   _nodes[i] = replacement;
2170       // }
2171       --i;  // Visit popped node
2172       // If it was last entry, loop terminates since size() was also reduced
2173     }
2174   }
2175 }
2176 
2177 //=============================================================================
2178 void Node_Stack::grow() {
2179   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2180   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2181   size_t max = old_max << 1;             // max * 2
2182   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2183   _inode_max = _inodes + max;
2184   _inode_top = _inodes + old_top;        // restore _top
2185 }
2186 
2187 // Node_Stack is used to map nodes.
2188 Node* Node_Stack::find(uint idx) const {
2189   uint sz = size();
2190   for (uint i=0; i < sz; i++) {
2191     if (idx == index_at(i) )
2192       return node_at(i);
2193   }
2194   return NULL;
2195 }
2196 
2197 //=============================================================================
2198 uint TypeNode::size_of() const { return sizeof(*this); }
2199 #ifndef PRODUCT
2200 void TypeNode::dump_spec(outputStream *st) const {
2201   if( !Verbose && !WizardMode ) {
2202     // standard dump does this in Verbose and WizardMode
2203     st->print(" #"); _type->dump_on(st);
2204   }
2205 }
2206 #endif
2207 uint TypeNode::hash() const {
2208   return Node::hash() + _type->hash();
2209 }
2210 uint TypeNode::cmp( const Node &n ) const
2211 { return !Type::cmp( _type, ((TypeNode&)n)._type ); }
2212 const Type *TypeNode::bottom_type() const { return _type; }
2213 const Type *TypeNode::Value( PhaseTransform * ) const { return _type; }
2214 
2215 //------------------------------ideal_reg--------------------------------------
2216 uint TypeNode::ideal_reg() const {
2217   return _type->ideal_reg();
2218 }