1 /*
   2  * Copyright (c) 1997, 2016, 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   // Avoid spec violation: Gap in prec edges.
 823   close_prec_gap_at(_cnt);
 824 }
 825 
 826 //------------------------------del_req_ordered--------------------------------
 827 // Delete the required edge and compact the edge array with preserved order
 828 void Node::del_req_ordered( 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   if (idx < --_cnt) {    // Not last edge ?
 836     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx)*sizeof(Node*)));
 837   }
 838   // Avoid spec violation: Gap in prec edges.
 839   close_prec_gap_at(_cnt);
 840 }
 841 
 842 //------------------------------ins_req----------------------------------------
 843 // Insert a new required input at the end
 844 void Node::ins_req( uint idx, Node *n ) {
 845   assert( is_not_dead(n), "can not use dead node");
 846   add_req(NULL);                // Make space
 847   assert( idx < _max, "Must have allocated enough space");
 848   // Slide over
 849   if(_cnt-idx-1 > 0) {
 850     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 851   }
 852   _in[idx] = n;                            // Stuff over old required edge
 853   if (n != NULL) n->add_out((Node *)this); // Add reciprocal def-use edge
 854 }
 855 
 856 //-----------------------------find_edge---------------------------------------
 857 int Node::find_edge(Node* n) {
 858   for (uint i = 0; i < len(); i++) {
 859     if (_in[i] == n)  return i;
 860   }
 861   return -1;
 862 }
 863 
 864 //----------------------------replace_edge-------------------------------------
 865 int Node::replace_edge(Node* old, Node* neww) {
 866   if (old == neww)  return 0;  // nothing to do
 867   uint nrep = 0;
 868   for (uint i = 0; i < len(); i++) {
 869     if (in(i) == old) {
 870       if (i < req()) {
 871         set_req(i, neww);
 872       } else {
 873         assert(find_prec_edge(neww) == -1, err_msg("spec violation: duplicated prec edge (node %d -> %d)", _idx, neww->_idx));
 874         set_prec(i, neww);
 875       }
 876       nrep++;
 877     }
 878   }
 879   return nrep;
 880 }
 881 
 882 /**
 883  * Replace input edges in the range pointing to 'old' node.
 884  */
 885 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end) {
 886   if (old == neww)  return 0;  // nothing to do
 887   uint nrep = 0;
 888   for (int i = start; i < end; i++) {
 889     if (in(i) == old) {
 890       set_req(i, neww);
 891       nrep++;
 892     }
 893   }
 894   return nrep;
 895 }
 896 
 897 //-------------------------disconnect_inputs-----------------------------------
 898 // NULL out all inputs to eliminate incoming Def-Use edges.
 899 // Return the number of edges between 'n' and 'this'
 900 int Node::disconnect_inputs(Node *n, Compile* C) {
 901   int edges_to_n = 0;
 902 
 903   uint cnt = req();
 904   for( uint i = 0; i < cnt; ++i ) {
 905     if( in(i) == 0 ) continue;
 906     if( in(i) == n ) ++edges_to_n;
 907     set_req(i, NULL);
 908   }
 909   // Remove precedence edges if any exist
 910   // Note: Safepoints may have precedence edges, even during parsing
 911   if( (req() != len()) && (in(req()) != NULL) ) {
 912     uint max = len();
 913     for( uint i = 0; i < max; ++i ) {
 914       if( in(i) == 0 ) continue;
 915       if( in(i) == n ) ++edges_to_n;
 916       set_prec(i, NULL);
 917     }
 918   }
 919 
 920   // Node::destruct requires all out edges be deleted first
 921   // debug_only(destruct();)   // no reuse benefit expected
 922   if (edges_to_n == 0) {
 923     C->record_dead_node(_idx);
 924   }
 925   return edges_to_n;
 926 }
 927 
 928 //-----------------------------uncast---------------------------------------
 929 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 930 // Strip away casting.  (It is depth-limited.)
 931 Node* Node::uncast() const {
 932   // Should be inline:
 933   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 934   if (is_ConstraintCast() || is_CheckCastPP())
 935     return uncast_helper(this);
 936   else
 937     return (Node*) this;
 938 }
 939 
 940 // Find out of current node that matches opcode.
 941 Node* Node::find_out_with(int opcode) {
 942   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 943     Node* use = fast_out(i);
 944     if (use->Opcode() == opcode) {
 945       return use;
 946     }
 947   }
 948   return NULL;
 949 }
 950 
 951 //---------------------------uncast_helper-------------------------------------
 952 Node* Node::uncast_helper(const Node* p) {
 953 #ifdef ASSERT
 954   uint depth_count = 0;
 955   const Node* orig_p = p;
 956 #endif
 957 
 958   while (true) {
 959 #ifdef ASSERT
 960     if (depth_count >= K) {
 961       orig_p->dump(4);
 962       if (p != orig_p)
 963         p->dump(1);
 964     }
 965     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
 966 #endif
 967     if (p == NULL || p->req() != 2) {
 968       break;
 969     } else if (p->is_ConstraintCast()) {
 970       p = p->in(1);
 971     } else if (p->is_CheckCastPP()) {
 972       p = p->in(1);
 973     } else {
 974       break;
 975     }
 976   }
 977   return (Node*) p;
 978 }
 979 
 980 //------------------------------add_prec---------------------------------------
 981 // Add a new precedence input.  Precedence inputs are unordered, with
 982 // duplicates removed and NULLs packed down at the end.
 983 void Node::add_prec( Node *n ) {
 984   assert( is_not_dead(n), "can not use dead node");
 985 
 986   // Check for NULL at end
 987   if( _cnt >= _max || in(_max-1) )
 988     grow( _max+1 );
 989 
 990   // Find a precedence edge to move
 991   uint i = _cnt;
 992   while( in(i) != NULL ) {
 993     if (in(i) == n) return; // Avoid spec violation: duplicated prec edge.
 994     i++;
 995   }
 996   _in[i] = n;                                // Stuff prec edge over NULL
 997   if ( n != NULL) n->add_out((Node *)this);  // Add mirror edge
 998 
 999 #ifdef ASSERT
1000   while ((++i)<_max) { assert(_in[i] == NULL, err_msg("spec violation: Gap in prec edges (node %d)", _idx)); }
1001 #endif
1002 }
1003 
1004 //------------------------------rm_prec----------------------------------------
1005 // Remove a precedence input.  Precedence inputs are unordered, with
1006 // duplicates removed and NULLs packed down at the end.
1007 void Node::rm_prec( uint j ) {
1008   assert(j < _max, err_msg("oob: i=%d, _max=%d", j, _max));
1009   assert(j >= _cnt, "not a precedence edge");
1010   if (_in[j] == NULL) return;   // Avoid spec violation: Gap in prec edges.
1011   _in[j]->del_out((Node *)this);
1012   close_prec_gap_at(j);
1013 }
1014 
1015 //------------------------------size_of----------------------------------------
1016 uint Node::size_of() const { return sizeof(*this); }
1017 
1018 //------------------------------ideal_reg--------------------------------------
1019 uint Node::ideal_reg() const { return 0; }
1020 
1021 //------------------------------jvms-------------------------------------------
1022 JVMState* Node::jvms() const { return NULL; }
1023 
1024 #ifdef ASSERT
1025 //------------------------------jvms-------------------------------------------
1026 bool Node::verify_jvms(const JVMState* using_jvms) const {
1027   for (JVMState* jvms = this->jvms(); jvms != NULL; jvms = jvms->caller()) {
1028     if (jvms == using_jvms)  return true;
1029   }
1030   return false;
1031 }
1032 
1033 //------------------------------init_NodeProperty------------------------------
1034 void Node::init_NodeProperty() {
1035   assert(_max_classes <= max_jushort, "too many NodeProperty classes");
1036   assert(_max_flags <= max_jushort, "too many NodeProperty flags");
1037 }
1038 #endif
1039 
1040 //------------------------------format-----------------------------------------
1041 // Print as assembly
1042 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
1043 //------------------------------emit-------------------------------------------
1044 // Emit bytes starting at parameter 'ptr'.
1045 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
1046 //------------------------------size-------------------------------------------
1047 // Size of instruction in bytes
1048 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
1049 
1050 //------------------------------CFG Construction-------------------------------
1051 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
1052 // Goto and Return.
1053 const Node *Node::is_block_proj() const { return 0; }
1054 
1055 // Minimum guaranteed type
1056 const Type *Node::bottom_type() const { return Type::BOTTOM; }
1057 
1058 
1059 //------------------------------raise_bottom_type------------------------------
1060 // Get the worst-case Type output for this Node.
1061 void Node::raise_bottom_type(const Type* new_type) {
1062   if (is_Type()) {
1063     TypeNode *n = this->as_Type();
1064     if (VerifyAliases) {
1065       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1066     }
1067     n->set_type(new_type);
1068   } else if (is_Load()) {
1069     LoadNode *n = this->as_Load();
1070     if (VerifyAliases) {
1071       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1072     }
1073     n->set_type(new_type);
1074   }
1075 }
1076 
1077 //------------------------------Identity---------------------------------------
1078 // Return a node that the given node is equivalent to.
1079 Node *Node::Identity( PhaseTransform * ) {
1080   return this;                  // Default to no identities
1081 }
1082 
1083 //------------------------------Value------------------------------------------
1084 // Compute a new Type for a node using the Type of the inputs.
1085 const Type *Node::Value( PhaseTransform * ) const {
1086   return bottom_type();         // Default to worst-case Type
1087 }
1088 
1089 //------------------------------Ideal------------------------------------------
1090 //
1091 // 'Idealize' the graph rooted at this Node.
1092 //
1093 // In order to be efficient and flexible there are some subtle invariants
1094 // these Ideal calls need to hold.  Running with '+VerifyIterativeGVN' checks
1095 // these invariants, although its too slow to have on by default.  If you are
1096 // hacking an Ideal call, be sure to test with +VerifyIterativeGVN!
1097 //
1098 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1099 // pointer.  If ANY change is made, it must return the root of the reshaped
1100 // graph - even if the root is the same Node.  Example: swapping the inputs
1101 // to an AddINode gives the same answer and same root, but you still have to
1102 // return the 'this' pointer instead of NULL.
1103 //
1104 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1105 // Identity call to return an old Node; basically if Identity can find
1106 // another Node have the Ideal call make no change and return NULL.
1107 // Example: AddINode::Ideal must check for add of zero; in this case it
1108 // returns NULL instead of doing any graph reshaping.
1109 //
1110 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1111 // sharing there may be other users of the old Nodes relying on their current
1112 // semantics.  Modifying them will break the other users.
1113 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1114 // "X+3" unchanged in case it is shared.
1115 //
1116 // If you modify the 'this' pointer's inputs, you should use
1117 // 'set_req'.  If you are making a new Node (either as the new root or
1118 // some new internal piece) you may use 'init_req' to set the initial
1119 // value.  You can make a new Node with either 'new' or 'clone'.  In
1120 // either case, def-use info is correctly maintained.
1121 //
1122 // Example: reshape "(X+3)+4" into "X+7":
1123 //    set_req(1, in(1)->in(1));
1124 //    set_req(2, phase->intcon(7));
1125 //    return this;
1126 // Example: reshape "X*4" into "X<<2"
1127 //    return new (C) LShiftINode(in(1), phase->intcon(2));
1128 //
1129 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1130 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1131 //    Node *shift=phase->transform(new(C)LShiftINode(in(1),phase->intcon(5)));
1132 //    return new (C) AddINode(shift, in(1));
1133 //
1134 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1135 // These forms are faster than 'phase->transform(new (C) ConNode())' and Do
1136 // The Right Thing with def-use info.
1137 //
1138 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1139 // graph uses the 'this' Node it must be the root.  If you want a Node with
1140 // the same Opcode as the 'this' pointer use 'clone'.
1141 //
1142 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1143   return NULL;                  // Default to being Ideal already
1144 }
1145 
1146 // Some nodes have specific Ideal subgraph transformations only if they are
1147 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1148 // for the transformations to happen.
1149 bool Node::has_special_unique_user() const {
1150   assert(outcnt() == 1, "match only for unique out");
1151   Node* n = unique_out();
1152   int op  = Opcode();
1153   if( this->is_Store() ) {
1154     // Condition for back-to-back stores folding.
1155     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1156   } else if (this->is_Load()) {
1157     // Condition for removing an unused LoadNode from the MemBarAcquire precedence input
1158     return n->Opcode() == Op_MemBarAcquire;
1159   } else if( op == Op_AddL ) {
1160     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1161     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1162   } else if( op == Op_SubI || op == Op_SubL ) {
1163     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1164     return n->Opcode() == op && n->in(2) == this;
1165   }
1166   return false;
1167 };
1168 
1169 //--------------------------find_exact_control---------------------------------
1170 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1171 Node* Node::find_exact_control(Node* ctrl) {
1172   if (ctrl == NULL && this->is_Region())
1173     ctrl = this->as_Region()->is_copy();
1174 
1175   if (ctrl != NULL && ctrl->is_CatchProj()) {
1176     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1177       ctrl = ctrl->in(0);
1178     if (ctrl != NULL && !ctrl->is_top())
1179       ctrl = ctrl->in(0);
1180   }
1181 
1182   if (ctrl != NULL && ctrl->is_Proj())
1183     ctrl = ctrl->in(0);
1184 
1185   return ctrl;
1186 }
1187 
1188 //--------------------------dominates------------------------------------------
1189 // Helper function for MemNode::all_controls_dominate().
1190 // Check if 'this' control node dominates or equal to 'sub' control node.
1191 // We already know that if any path back to Root or Start reaches 'this',
1192 // then all paths so, so this is a simple search for one example,
1193 // not an exhaustive search for a counterexample.
1194 bool Node::dominates(Node* sub, Node_List &nlist) {
1195   assert(this->is_CFG(), "expecting control");
1196   assert(sub != NULL && sub->is_CFG(), "expecting control");
1197 
1198   // detect dead cycle without regions
1199   int iterations_without_region_limit = DominatorSearchLimit;
1200 
1201   Node* orig_sub = sub;
1202   Node* dom      = this;
1203   bool  met_dom  = false;
1204   nlist.clear();
1205 
1206   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1207   // After seeing 'dom', continue up to Root or Start.
1208   // If we hit a region (backward split point), it may be a loop head.
1209   // Keep going through one of the region's inputs.  If we reach the
1210   // same region again, go through a different input.  Eventually we
1211   // will either exit through the loop head, or give up.
1212   // (If we get confused, break out and return a conservative 'false'.)
1213   while (sub != NULL) {
1214     if (sub->is_top())  break; // Conservative answer for dead code.
1215     if (sub == dom) {
1216       if (nlist.size() == 0) {
1217         // No Region nodes except loops were visited before and the EntryControl
1218         // path was taken for loops: it did not walk in a cycle.
1219         return true;
1220       } else if (met_dom) {
1221         break;          // already met before: walk in a cycle
1222       } else {
1223         // Region nodes were visited. Continue walk up to Start or Root
1224         // to make sure that it did not walk in a cycle.
1225         met_dom = true; // first time meet
1226         iterations_without_region_limit = DominatorSearchLimit; // Reset
1227      }
1228     }
1229     if (sub->is_Start() || sub->is_Root()) {
1230       // Success if we met 'dom' along a path to Start or Root.
1231       // We assume there are no alternative paths that avoid 'dom'.
1232       // (This assumption is up to the caller to ensure!)
1233       return met_dom;
1234     }
1235     Node* up = sub->in(0);
1236     // Normalize simple pass-through regions and projections:
1237     up = sub->find_exact_control(up);
1238     // If sub == up, we found a self-loop.  Try to push past it.
1239     if (sub == up && sub->is_Loop()) {
1240       // Take loop entry path on the way up to 'dom'.
1241       up = sub->in(1); // in(LoopNode::EntryControl);
1242     } else if (sub == up && sub->is_Region() && sub->req() != 3) {
1243       // Always take in(1) path on the way up to 'dom' for clone regions
1244       // (with only one input) or regions which merge > 2 paths
1245       // (usually used to merge fast/slow paths).
1246       up = sub->in(1);
1247     } else if (sub == up && sub->is_Region()) {
1248       // Try both paths for Regions with 2 input paths (it may be a loop head).
1249       // It could give conservative 'false' answer without information
1250       // which region's input is the entry path.
1251       iterations_without_region_limit = DominatorSearchLimit; // Reset
1252 
1253       bool region_was_visited_before = false;
1254       // Was this Region node visited before?
1255       // If so, we have reached it because we accidentally took a
1256       // loop-back edge from 'sub' back into the body of the loop,
1257       // and worked our way up again to the loop header 'sub'.
1258       // So, take the first unexplored path on the way up to 'dom'.
1259       for (int j = nlist.size() - 1; j >= 0; j--) {
1260         intptr_t ni = (intptr_t)nlist.at(j);
1261         Node* visited = (Node*)(ni & ~1);
1262         bool  visited_twice_already = ((ni & 1) != 0);
1263         if (visited == sub) {
1264           if (visited_twice_already) {
1265             // Visited 2 paths, but still stuck in loop body.  Give up.
1266             return false;
1267           }
1268           // The Region node was visited before only once.
1269           // (We will repush with the low bit set, below.)
1270           nlist.remove(j);
1271           // We will find a new edge and re-insert.
1272           region_was_visited_before = true;
1273           break;
1274         }
1275       }
1276 
1277       // Find an incoming edge which has not been seen yet; walk through it.
1278       assert(up == sub, "");
1279       uint skip = region_was_visited_before ? 1 : 0;
1280       for (uint i = 1; i < sub->req(); i++) {
1281         Node* in = sub->in(i);
1282         if (in != NULL && !in->is_top() && in != sub) {
1283           if (skip == 0) {
1284             up = in;
1285             break;
1286           }
1287           --skip;               // skip this nontrivial input
1288         }
1289       }
1290 
1291       // Set 0 bit to indicate that both paths were taken.
1292       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1293     }
1294 
1295     if (up == sub) {
1296       break;    // some kind of tight cycle
1297     }
1298     if (up == orig_sub && met_dom) {
1299       // returned back after visiting 'dom'
1300       break;    // some kind of cycle
1301     }
1302     if (--iterations_without_region_limit < 0) {
1303       break;    // dead cycle
1304     }
1305     sub = up;
1306   }
1307 
1308   // Did not meet Root or Start node in pred. chain.
1309   // Conservative answer for dead code.
1310   return false;
1311 }
1312 
1313 //------------------------------remove_dead_region-----------------------------
1314 // This control node is dead.  Follow the subgraph below it making everything
1315 // using it dead as well.  This will happen normally via the usual IterGVN
1316 // worklist but this call is more efficient.  Do not update use-def info
1317 // inside the dead region, just at the borders.
1318 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1319   // Con's are a popular node to re-hit in the hash table again.
1320   if( dead->is_Con() ) return;
1321 
1322   // Can't put ResourceMark here since igvn->_worklist uses the same arena
1323   // for verify pass with +VerifyOpto and we add/remove elements in it here.
1324   Node_List  nstack(Thread::current()->resource_area());
1325 
1326   Node *top = igvn->C->top();
1327   nstack.push(dead);
1328   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1329 
1330   while (nstack.size() > 0) {
1331     dead = nstack.pop();
1332     if (dead->Opcode() == Op_SafePoint) {
1333       dead->as_SafePoint()->disconnect_from_root(igvn);
1334     }
1335     if (dead->outcnt() > 0) {
1336       // Keep dead node on stack until all uses are processed.
1337       nstack.push(dead);
1338       // For all Users of the Dead...    ;-)
1339       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1340         Node* use = dead->last_out(k);
1341         igvn->hash_delete(use);       // Yank from hash table prior to mod
1342         if (use->in(0) == dead) {     // Found another dead node
1343           assert (!use->is_Con(), "Control for Con node should be Root node.");
1344           use->set_req(0, top);       // Cut dead edge to prevent processing
1345           nstack.push(use);           // the dead node again.
1346         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1347                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1348                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1349           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1350           use->set_req(0, top);       // Cut self edge
1351           nstack.push(use);
1352         } else {                      // Else found a not-dead user
1353           // Dead if all inputs are top or null
1354           bool dead_use = !use->is_Root(); // Keep empty graph alive
1355           for (uint j = 1; j < use->req(); j++) {
1356             Node* in = use->in(j);
1357             if (in == dead) {         // Turn all dead inputs into TOP
1358               use->set_req(j, top);
1359             } else if (in != NULL && !in->is_top()) {
1360               dead_use = false;
1361             }
1362           }
1363           if (dead_use) {
1364             if (use->is_Region()) {
1365               use->set_req(0, top);   // Cut self edge
1366             }
1367             nstack.push(use);
1368           } else {
1369             igvn->_worklist.push(use);
1370           }
1371         }
1372         // Refresh the iterator, since any number of kills might have happened.
1373         k = dead->last_outs(kmin);
1374       }
1375     } else { // (dead->outcnt() == 0)
1376       // Done with outputs.
1377       igvn->hash_delete(dead);
1378       igvn->_worklist.remove(dead);
1379       igvn->set_type(dead, Type::TOP);
1380       if (dead->is_macro()) {
1381         igvn->C->remove_macro_node(dead);
1382       }
1383       if (dead->is_expensive()) {
1384         igvn->C->remove_expensive_node(dead);
1385       }
1386       CastIINode* cast = dead->isa_CastII();
1387       if (cast != NULL && cast->has_range_check()) {
1388         igvn->C->remove_range_check_cast(cast);
1389       }
1390       igvn->C->record_dead_node(dead->_idx);
1391       // Kill all inputs to the dead guy
1392       for (uint i=0; i < dead->req(); i++) {
1393         Node *n = dead->in(i);      // Get input to dead guy
1394         if (n != NULL && !n->is_top()) { // Input is valid?
1395           dead->set_req(i, top);    // Smash input away
1396           if (n->outcnt() == 0) {   // Input also goes dead?
1397             if (!n->is_Con())
1398               nstack.push(n);       // Clear it out as well
1399           } else if (n->outcnt() == 1 &&
1400                      n->has_special_unique_user()) {
1401             igvn->add_users_to_worklist( n );
1402           } else if (n->outcnt() <= 2 && n->is_Store()) {
1403             // Push store's uses on worklist to enable folding optimization for
1404             // store/store and store/load to the same address.
1405             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1406             // and remove_globally_dead_node().
1407             igvn->add_users_to_worklist( n );
1408           }
1409         }
1410       }
1411     } // (dead->outcnt() == 0)
1412   }   // while (nstack.size() > 0) for outputs
1413   return;
1414 }
1415 
1416 //------------------------------remove_dead_region-----------------------------
1417 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1418   Node *n = in(0);
1419   if( !n ) return false;
1420   // Lost control into this guy?  I.e., it became unreachable?
1421   // Aggressively kill all unreachable code.
1422   if (can_reshape && n->is_top()) {
1423     kill_dead_code(this, phase->is_IterGVN());
1424     return false; // Node is dead.
1425   }
1426 
1427   if( n->is_Region() && n->as_Region()->is_copy() ) {
1428     Node *m = n->nonnull_req();
1429     set_req(0, m);
1430     return true;
1431   }
1432   return false;
1433 }
1434 
1435 //------------------------------Ideal_DU_postCCP-------------------------------
1436 // Idealize graph, using DU info.  Must clone result into new-space
1437 Node *Node::Ideal_DU_postCCP( PhaseCCP * ) {
1438   return NULL;                 // Default to no change
1439 }
1440 
1441 //------------------------------hash-------------------------------------------
1442 // Hash function over Nodes.
1443 uint Node::hash() const {
1444   uint sum = 0;
1445   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1446     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded NULLs
1447   return (sum>>2) + _cnt + Opcode();
1448 }
1449 
1450 //------------------------------cmp--------------------------------------------
1451 // Compare special parts of simple Nodes
1452 uint Node::cmp( const Node &n ) const {
1453   return 1;                     // Must be same
1454 }
1455 
1456 //------------------------------rematerialize-----------------------------------
1457 // Should we clone rather than spill this instruction?
1458 bool Node::rematerialize() const {
1459   if ( is_Mach() )
1460     return this->as_Mach()->rematerialize();
1461   else
1462     return (_flags & Flag_rematerialize) != 0;
1463 }
1464 
1465 //------------------------------needs_anti_dependence_check---------------------
1466 // Nodes which use memory without consuming it, hence need antidependences.
1467 bool Node::needs_anti_dependence_check() const {
1468   if( req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0 )
1469     return false;
1470   else
1471     return in(1)->bottom_type()->has_memory();
1472 }
1473 
1474 
1475 // Get an integer constant from a ConNode (or CastIINode).
1476 // Return a default value if there is no apparent constant here.
1477 const TypeInt* Node::find_int_type() const {
1478   if (this->is_Type()) {
1479     return this->as_Type()->type()->isa_int();
1480   } else if (this->is_Con()) {
1481     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1482     return this->bottom_type()->isa_int();
1483   }
1484   return NULL;
1485 }
1486 
1487 // Get a pointer constant from a ConstNode.
1488 // Returns the constant if it is a pointer ConstNode
1489 intptr_t Node::get_ptr() const {
1490   assert( Opcode() == Op_ConP, "" );
1491   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1492 }
1493 
1494 // Get a narrow oop constant from a ConNNode.
1495 intptr_t Node::get_narrowcon() const {
1496   assert( Opcode() == Op_ConN, "" );
1497   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1498 }
1499 
1500 // Get a long constant from a ConNode.
1501 // Return a default value if there is no apparent constant here.
1502 const TypeLong* Node::find_long_type() const {
1503   if (this->is_Type()) {
1504     return this->as_Type()->type()->isa_long();
1505   } else if (this->is_Con()) {
1506     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1507     return this->bottom_type()->isa_long();
1508   }
1509   return NULL;
1510 }
1511 
1512 
1513 /**
1514  * Return a ptr type for nodes which should have it.
1515  */
1516 const TypePtr* Node::get_ptr_type() const {
1517   const TypePtr* tp = this->bottom_type()->make_ptr();
1518 #ifdef ASSERT
1519   if (tp == NULL) {
1520     this->dump(1);
1521     assert((tp != NULL), "unexpected node type");
1522   }
1523 #endif
1524   return tp;
1525 }
1526 
1527 // Get a double constant from a ConstNode.
1528 // Returns the constant if it is a double ConstNode
1529 jdouble Node::getd() const {
1530   assert( Opcode() == Op_ConD, "" );
1531   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1532 }
1533 
1534 // Get a float constant from a ConstNode.
1535 // Returns the constant if it is a float ConstNode
1536 jfloat Node::getf() const {
1537   assert( Opcode() == Op_ConF, "" );
1538   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1539 }
1540 
1541 #ifndef PRODUCT
1542 
1543 //----------------------------NotANode----------------------------------------
1544 // Used in debugging code to avoid walking across dead or uninitialized edges.
1545 static inline bool NotANode(const Node* n) {
1546   if (n == NULL)                   return true;
1547   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
1548   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
1549   return false;
1550 }
1551 
1552 
1553 //------------------------------find------------------------------------------
1554 // Find a neighbor of this Node with the given _idx
1555 // If idx is negative, find its absolute value, following both _in and _out.
1556 static void find_recur(Compile* C,  Node* &result, Node *n, int idx, bool only_ctrl,
1557                         VectorSet* old_space, VectorSet* new_space ) {
1558   int node_idx = (idx >= 0) ? idx : -idx;
1559   if (NotANode(n))  return;  // Gracefully handle NULL, -1, 0xabababab, etc.
1560   // Contained in new_space or old_space?   Check old_arena first since it's mostly empty.
1561   VectorSet *v = C->old_arena()->contains(n) ? old_space : new_space;
1562   if( v->test(n->_idx) ) return;
1563   if( (int)n->_idx == node_idx
1564       debug_only(|| n->debug_idx() == node_idx) ) {
1565     if (result != NULL)
1566       tty->print("find: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1567                  (uintptr_t)result, (uintptr_t)n, node_idx);
1568     result = n;
1569   }
1570   v->set(n->_idx);
1571   for( uint i=0; i<n->len(); i++ ) {
1572     if( only_ctrl && !(n->is_Region()) && (n->Opcode() != Op_Root) && (i != TypeFunc::Control) ) continue;
1573     find_recur(C, result, n->in(i), idx, only_ctrl, old_space, new_space );
1574   }
1575   // Search along forward edges also:
1576   if (idx < 0 && !only_ctrl) {
1577     for( uint j=0; j<n->outcnt(); j++ ) {
1578       find_recur(C, result, n->raw_out(j), idx, only_ctrl, old_space, new_space );
1579     }
1580   }
1581 #ifdef ASSERT
1582   // Search along debug_orig edges last, checking for cycles
1583   Node* orig = n->debug_orig();
1584   if (orig != NULL) {
1585     do {
1586       if (NotANode(orig))  break;
1587       find_recur(C, result, orig, idx, only_ctrl, old_space, new_space );
1588       orig = orig->debug_orig();
1589     } while (orig != NULL && orig != n->debug_orig());
1590   }
1591 #endif //ASSERT
1592 }
1593 
1594 // call this from debugger:
1595 Node* find_node(Node* n, int idx) {
1596   return n->find(idx);
1597 }
1598 
1599 //------------------------------find-------------------------------------------
1600 Node* Node::find(int idx) const {
1601   ResourceArea *area = Thread::current()->resource_area();
1602   VectorSet old_space(area), new_space(area);
1603   Node* result = NULL;
1604   find_recur(Compile::current(), result, (Node*) this, idx, false, &old_space, &new_space );
1605   return result;
1606 }
1607 
1608 //------------------------------find_ctrl--------------------------------------
1609 // Find an ancestor to this node in the control history with given _idx
1610 Node* Node::find_ctrl(int idx) const {
1611   ResourceArea *area = Thread::current()->resource_area();
1612   VectorSet old_space(area), new_space(area);
1613   Node* result = NULL;
1614   find_recur(Compile::current(), result, (Node*) this, idx, true, &old_space, &new_space );
1615   return result;
1616 }
1617 #endif
1618 
1619 
1620 
1621 #ifndef PRODUCT
1622 
1623 // -----------------------------Name-------------------------------------------
1624 extern const char *NodeClassNames[];
1625 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
1626 
1627 static bool is_disconnected(const Node* n) {
1628   for (uint i = 0; i < n->req(); i++) {
1629     if (n->in(i) != NULL)  return false;
1630   }
1631   return true;
1632 }
1633 
1634 #ifdef ASSERT
1635 static void dump_orig(Node* orig, outputStream *st) {
1636   Compile* C = Compile::current();
1637   if (NotANode(orig)) orig = NULL;
1638   if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1639   if (orig == NULL) return;
1640   st->print(" !orig=");
1641   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
1642   if (NotANode(fast)) fast = NULL;
1643   while (orig != NULL) {
1644     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
1645     if (discon) st->print("[");
1646     if (!Compile::current()->node_arena()->contains(orig))
1647       st->print("o");
1648     st->print("%d", orig->_idx);
1649     if (discon) st->print("]");
1650     orig = orig->debug_orig();
1651     if (NotANode(orig)) orig = NULL;
1652     if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1653     if (orig != NULL) st->print(",");
1654     if (fast != NULL) {
1655       // Step fast twice for each single step of orig:
1656       fast = fast->debug_orig();
1657       if (NotANode(fast)) fast = NULL;
1658       if (fast != NULL && fast != orig) {
1659         fast = fast->debug_orig();
1660         if (NotANode(fast)) fast = NULL;
1661       }
1662       if (fast == orig) {
1663         st->print("...");
1664         break;
1665       }
1666     }
1667   }
1668 }
1669 
1670 void Node::set_debug_orig(Node* orig) {
1671   _debug_orig = orig;
1672   if (BreakAtNode == 0)  return;
1673   if (NotANode(orig))  orig = NULL;
1674   int trip = 10;
1675   while (orig != NULL) {
1676     if (orig->debug_idx() == BreakAtNode || (int)orig->_idx == BreakAtNode) {
1677       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d orig._idx=%d orig._debug_idx=%d",
1678                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
1679       BREAKPOINT;
1680     }
1681     orig = orig->debug_orig();
1682     if (NotANode(orig))  orig = NULL;
1683     if (trip-- <= 0)  break;
1684   }
1685 }
1686 #endif //ASSERT
1687 
1688 //------------------------------dump------------------------------------------
1689 // Dump a Node
1690 void Node::dump(const char* suffix, outputStream *st) const {
1691   Compile* C = Compile::current();
1692   bool is_new = C->node_arena()->contains(this);
1693   C->_in_dump_cnt++;
1694   st->print("%c%d\t%s\t=== ", is_new ? ' ' : 'o', _idx, Name());
1695 
1696   // Dump the required and precedence inputs
1697   dump_req(st);
1698   dump_prec(st);
1699   // Dump the outputs
1700   dump_out(st);
1701 
1702   if (is_disconnected(this)) {
1703 #ifdef ASSERT
1704     st->print("  [%d]",debug_idx());
1705     dump_orig(debug_orig(), st);
1706 #endif
1707     st->cr();
1708     C->_in_dump_cnt--;
1709     return;                     // don't process dead nodes
1710   }
1711 
1712   // Dump node-specific info
1713   dump_spec(st);
1714 #ifdef ASSERT
1715   // Dump the non-reset _debug_idx
1716   if (Verbose && WizardMode) {
1717     st->print("  [%d]",debug_idx());
1718   }
1719 #endif
1720 
1721   const Type *t = bottom_type();
1722 
1723   if (t != NULL && (t->isa_instptr() || t->isa_klassptr())) {
1724     const TypeInstPtr  *toop = t->isa_instptr();
1725     const TypeKlassPtr *tkls = t->isa_klassptr();
1726     ciKlass*           klass = toop ? toop->klass() : (tkls ? tkls->klass() : NULL );
1727     if (klass && klass->is_loaded() && klass->is_interface()) {
1728       st->print("  Interface:");
1729     } else if (toop) {
1730       st->print("  Oop:");
1731     } else if (tkls) {
1732       st->print("  Klass:");
1733     }
1734     t->dump_on(st);
1735   } else if (t == Type::MEMORY) {
1736     st->print("  Memory:");
1737     MemNode::dump_adr_type(this, adr_type(), st);
1738   } else if (Verbose || WizardMode) {
1739     st->print("  Type:");
1740     if (t) {
1741       t->dump_on(st);
1742     } else {
1743       st->print("no type");
1744     }
1745   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
1746     // Dump MachSpillcopy vector type.
1747     t->dump_on(st);
1748   }
1749   if (is_new) {
1750     debug_only(dump_orig(debug_orig(), st));
1751     Node_Notes* nn = C->node_notes_at(_idx);
1752     if (nn != NULL && !nn->is_clear()) {
1753       if (nn->jvms() != NULL) {
1754         st->print(" !jvms:");
1755         nn->jvms()->dump_spec(st);
1756       }
1757     }
1758   }
1759   if (suffix) st->print("%s", suffix);
1760   C->_in_dump_cnt--;
1761 }
1762 
1763 //------------------------------dump_req--------------------------------------
1764 void Node::dump_req(outputStream *st) const {
1765   // Dump the required input edges
1766   for (uint i = 0; i < req(); i++) {    // For all required inputs
1767     Node* d = in(i);
1768     if (d == NULL) {
1769       st->print("_ ");
1770     } else if (NotANode(d)) {
1771       st->print("NotANode ");  // uninitialized, sentinel, garbage, etc.
1772     } else {
1773       st->print("%c%d ", Compile::current()->node_arena()->contains(d) ? ' ' : 'o', d->_idx);
1774     }
1775   }
1776 }
1777 
1778 
1779 //------------------------------dump_prec-------------------------------------
1780 void Node::dump_prec(outputStream *st) const {
1781   // Dump the precedence edges
1782   int any_prec = 0;
1783   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
1784     Node* p = in(i);
1785     if (p != NULL) {
1786       if (!any_prec++) st->print(" |");
1787       if (NotANode(p)) { st->print("NotANode "); continue; }
1788       st->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
1789     }
1790   }
1791 }
1792 
1793 //------------------------------dump_out--------------------------------------
1794 void Node::dump_out(outputStream *st) const {
1795   // Delimit the output edges
1796   st->print(" [[");
1797   // Dump the output edges
1798   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
1799     Node* u = _out[i];
1800     if (u == NULL) {
1801       st->print("_ ");
1802     } else if (NotANode(u)) {
1803       st->print("NotANode ");
1804     } else {
1805       st->print("%c%d ", Compile::current()->node_arena()->contains(u) ? ' ' : 'o', u->_idx);
1806     }
1807   }
1808   st->print("]] ");
1809 }
1810 
1811 //------------------------------dump_nodes-------------------------------------
1812 static void dump_nodes(const Node* start, int d, bool only_ctrl) {
1813   Node* s = (Node*)start; // remove const
1814   if (NotANode(s)) return;
1815 
1816   uint depth = (uint)ABS(d);
1817   int direction = d;
1818   Compile* C = Compile::current();
1819   GrowableArray <Node *> nstack(C->live_nodes());
1820 
1821   nstack.append(s);
1822   int begin = 0;
1823   int end = 0;
1824   for(uint i = 0; i < depth; i++) {
1825     end = nstack.length();
1826     for(int j = begin; j < end; j++) {
1827       Node* tp  = nstack.at(j);
1828       uint limit = direction > 0 ? tp->len() : tp->outcnt();
1829       for(uint k = 0; k < limit; k++) {
1830         Node* n = direction > 0 ? tp->in(k) : tp->raw_out(k);
1831 
1832         if (NotANode(n))  continue;
1833         // do not recurse through top or the root (would reach unrelated stuff)
1834         if (n->is_Root() || n->is_top())  continue;
1835         if (only_ctrl && !n->is_CFG()) continue;
1836 
1837         bool on_stack = nstack.contains(n);
1838         if (!on_stack) {
1839           nstack.append(n);
1840         }
1841       }
1842     }
1843     begin = end;
1844   }
1845   end = nstack.length();
1846   if (direction > 0) {
1847     for(int j = end-1; j >= 0; j--) {
1848       nstack.at(j)->dump();
1849     }
1850   } else {
1851     for(int j = 0; j < end; j++) {
1852       nstack.at(j)->dump();
1853     }
1854   }
1855 }
1856 
1857 //------------------------------dump-------------------------------------------
1858 void Node::dump(int d) const {
1859   dump_nodes(this, d, false);
1860 }
1861 
1862 //------------------------------dump_ctrl--------------------------------------
1863 // Dump a Node's control history to depth
1864 void Node::dump_ctrl(int d) const {
1865   dump_nodes(this, d, true);
1866 }
1867 
1868 // VERIFICATION CODE
1869 // For each input edge to a node (ie - for each Use-Def edge), verify that
1870 // there is a corresponding Def-Use edge.
1871 //------------------------------verify_edges-----------------------------------
1872 void Node::verify_edges(Unique_Node_List &visited) {
1873   uint i, j, idx;
1874   int  cnt;
1875   Node *n;
1876 
1877   // Recursive termination test
1878   if (visited.member(this))  return;
1879   visited.push(this);
1880 
1881   // Walk over all input edges, checking for correspondence
1882   for( i = 0; i < len(); i++ ) {
1883     n = in(i);
1884     if (n != NULL && !n->is_top()) {
1885       // Count instances of (Node *)this
1886       cnt = 0;
1887       for (idx = 0; idx < n->_outcnt; idx++ ) {
1888         if (n->_out[idx] == (Node *)this)  cnt++;
1889       }
1890       assert( cnt > 0,"Failed to find Def-Use edge." );
1891       // Check for duplicate edges
1892       // walk the input array downcounting the input edges to n
1893       for( j = 0; j < len(); j++ ) {
1894         if( in(j) == n ) cnt--;
1895       }
1896       assert( cnt == 0,"Mismatched edge count.");
1897     } else if (n == NULL) {
1898       assert(i >= req() || i == 0 || is_Region() || is_Phi(), "only regions or phis have null data edges");
1899     } else {
1900       assert(n->is_top(), "sanity");
1901       // Nothing to check.
1902     }
1903   }
1904   // Recursive walk over all input edges
1905   for( i = 0; i < len(); i++ ) {
1906     n = in(i);
1907     if( n != NULL )
1908       in(i)->verify_edges(visited);
1909   }
1910 }
1911 
1912 //------------------------------verify_recur-----------------------------------
1913 static const Node *unique_top = NULL;
1914 
1915 void Node::verify_recur(const Node *n, int verify_depth,
1916                         VectorSet &old_space, VectorSet &new_space) {
1917   if ( verify_depth == 0 )  return;
1918   if (verify_depth > 0)  --verify_depth;
1919 
1920   Compile* C = Compile::current();
1921 
1922   // Contained in new_space or old_space?
1923   VectorSet *v = C->node_arena()->contains(n) ? &new_space : &old_space;
1924   // Check for visited in the proper space.  Numberings are not unique
1925   // across spaces so we need a separate VectorSet for each space.
1926   if( v->test_set(n->_idx) ) return;
1927 
1928   if (n->is_Con() && n->bottom_type() == Type::TOP) {
1929     if (C->cached_top_node() == NULL)
1930       C->set_cached_top_node((Node*)n);
1931     assert(C->cached_top_node() == n, "TOP node must be unique");
1932   }
1933 
1934   for( uint i = 0; i < n->len(); i++ ) {
1935     Node *x = n->in(i);
1936     if (!x || x->is_top()) continue;
1937 
1938     // Verify my input has a def-use edge to me
1939     if (true /*VerifyDefUse*/) {
1940       // Count use-def edges from n to x
1941       int cnt = 0;
1942       for( uint j = 0; j < n->len(); j++ )
1943         if( n->in(j) == x )
1944           cnt++;
1945       // Count def-use edges from x to n
1946       uint max = x->_outcnt;
1947       for( uint k = 0; k < max; k++ )
1948         if (x->_out[k] == n)
1949           cnt--;
1950       assert( cnt == 0, "mismatched def-use edge counts" );
1951     }
1952 
1953     verify_recur(x, verify_depth, old_space, new_space);
1954   }
1955 
1956 }
1957 
1958 //------------------------------verify-----------------------------------------
1959 // Check Def-Use info for my subgraph
1960 void Node::verify() const {
1961   Compile* C = Compile::current();
1962   Node* old_top = C->cached_top_node();
1963   ResourceMark rm;
1964   ResourceArea *area = Thread::current()->resource_area();
1965   VectorSet old_space(area), new_space(area);
1966   verify_recur(this, -1, old_space, new_space);
1967   C->set_cached_top_node(old_top);
1968 }
1969 #endif
1970 
1971 
1972 //------------------------------walk-------------------------------------------
1973 // Graph walk, with both pre-order and post-order functions
1974 void Node::walk(NFunc pre, NFunc post, void *env) {
1975   VectorSet visited(Thread::current()->resource_area()); // Setup for local walk
1976   walk_(pre, post, env, visited);
1977 }
1978 
1979 void Node::walk_(NFunc pre, NFunc post, void *env, VectorSet &visited) {
1980   if( visited.test_set(_idx) ) return;
1981   pre(*this,env);               // Call the pre-order walk function
1982   for( uint i=0; i<_max; i++ )
1983     if( in(i) )                 // Input exists and is not walked?
1984       in(i)->walk_(pre,post,env,visited); // Walk it with pre & post functions
1985   post(*this,env);              // Call the post-order walk function
1986 }
1987 
1988 void Node::nop(Node &, void*) {}
1989 
1990 //------------------------------Registers--------------------------------------
1991 // Do we Match on this edge index or not?  Generally false for Control
1992 // and true for everything else.  Weird for calls & returns.
1993 uint Node::match_edge(uint idx) const {
1994   return idx;                   // True for other than index 0 (control)
1995 }
1996 
1997 static RegMask _not_used_at_all;
1998 // Register classes are defined for specific machines
1999 const RegMask &Node::out_RegMask() const {
2000   ShouldNotCallThis();
2001   return _not_used_at_all;
2002 }
2003 
2004 const RegMask &Node::in_RegMask(uint) const {
2005   ShouldNotCallThis();
2006   return _not_used_at_all;
2007 }
2008 
2009 //=============================================================================
2010 //-----------------------------------------------------------------------------
2011 void Node_Array::reset( Arena *new_arena ) {
2012   _a->Afree(_nodes,_max*sizeof(Node*));
2013   _max   = 0;
2014   _nodes = NULL;
2015   _a     = new_arena;
2016 }
2017 
2018 //------------------------------clear------------------------------------------
2019 // Clear all entries in _nodes to NULL but keep storage
2020 void Node_Array::clear() {
2021   Copy::zero_to_bytes( _nodes, _max*sizeof(Node*) );
2022 }
2023 
2024 //-----------------------------------------------------------------------------
2025 void Node_Array::grow( uint i ) {
2026   if( !_max ) {
2027     _max = 1;
2028     _nodes = (Node**)_a->Amalloc( _max * sizeof(Node*) );
2029     _nodes[0] = NULL;
2030   }
2031   uint old = _max;
2032   while( i >= _max ) _max <<= 1;        // Double to fit
2033   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
2034   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
2035 }
2036 
2037 //-----------------------------------------------------------------------------
2038 void Node_Array::insert( uint i, Node *n ) {
2039   if( _nodes[_max-1] ) grow(_max);      // Get more space if full
2040   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i+1], ((_max-i-1)*sizeof(Node*)));
2041   _nodes[i] = n;
2042 }
2043 
2044 //-----------------------------------------------------------------------------
2045 void Node_Array::remove( uint i ) {
2046   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i+1], (HeapWord*)&_nodes[i], ((_max-i-1)*sizeof(Node*)));
2047   _nodes[_max-1] = NULL;
2048 }
2049 
2050 //-----------------------------------------------------------------------------
2051 void Node_Array::sort( C_sort_func_t func) {
2052   qsort( _nodes, _max, sizeof( Node* ), func );
2053 }
2054 
2055 //-----------------------------------------------------------------------------
2056 void Node_Array::dump() const {
2057 #ifndef PRODUCT
2058   for( uint i = 0; i < _max; i++ ) {
2059     Node *nn = _nodes[i];
2060     if( nn != NULL ) {
2061       tty->print("%5d--> ",i); nn->dump();
2062     }
2063   }
2064 #endif
2065 }
2066 
2067 //--------------------------is_iteratively_computed------------------------------
2068 // Operation appears to be iteratively computed (such as an induction variable)
2069 // It is possible for this operation to return false for a loop-varying
2070 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2071 bool Node::is_iteratively_computed() {
2072   if (ideal_reg()) { // does operation have a result register?
2073     for (uint i = 1; i < req(); i++) {
2074       Node* n = in(i);
2075       if (n != NULL && n->is_Phi()) {
2076         for (uint j = 1; j < n->req(); j++) {
2077           if (n->in(j) == this) {
2078             return true;
2079           }
2080         }
2081       }
2082     }
2083   }
2084   return false;
2085 }
2086 
2087 //--------------------------find_similar------------------------------
2088 // Return a node with opcode "opc" and same inputs as "this" if one can
2089 // be found; Otherwise return NULL;
2090 Node* Node::find_similar(int opc) {
2091   if (req() >= 2) {
2092     Node* def = in(1);
2093     if (def && def->outcnt() >= 2) {
2094       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2095         Node* use = def->fast_out(i);
2096         if (use->Opcode() == opc &&
2097             use->req() == req()) {
2098           uint j;
2099           for (j = 0; j < use->req(); j++) {
2100             if (use->in(j) != in(j)) {
2101               break;
2102             }
2103           }
2104           if (j == use->req()) {
2105             return use;
2106           }
2107         }
2108       }
2109     }
2110   }
2111   return NULL;
2112 }
2113 
2114 
2115 //--------------------------unique_ctrl_out------------------------------
2116 // Return the unique control out if only one. Null if none or more than one.
2117 Node* Node::unique_ctrl_out() {
2118   Node* found = NULL;
2119   for (uint i = 0; i < outcnt(); i++) {
2120     Node* use = raw_out(i);
2121     if (use->is_CFG() && use != this) {
2122       if (found != NULL) return NULL;
2123       found = use;
2124     }
2125   }
2126   return found;
2127 }
2128 
2129 //=============================================================================
2130 //------------------------------yank-------------------------------------------
2131 // Find and remove
2132 void Node_List::yank( Node *n ) {
2133   uint i;
2134   for( i = 0; i < _cnt; i++ )
2135     if( _nodes[i] == n )
2136       break;
2137 
2138   if( i < _cnt )
2139     _nodes[i] = _nodes[--_cnt];
2140 }
2141 
2142 //------------------------------dump-------------------------------------------
2143 void Node_List::dump() const {
2144 #ifndef PRODUCT
2145   for( uint i = 0; i < _cnt; i++ )
2146     if( _nodes[i] ) {
2147       tty->print("%5d--> ",i);
2148       _nodes[i]->dump();
2149     }
2150 #endif
2151 }
2152 
2153 void Node_List::dump_simple() const {
2154 #ifndef PRODUCT
2155   for( uint i = 0; i < _cnt; i++ )
2156     if( _nodes[i] ) {
2157       tty->print(" %d", _nodes[i]->_idx);
2158     } else {
2159       tty->print(" NULL");
2160     }
2161 #endif
2162 }
2163 
2164 //=============================================================================
2165 //------------------------------remove-----------------------------------------
2166 void Unique_Node_List::remove( Node *n ) {
2167   if( _in_worklist[n->_idx] ) {
2168     for( uint i = 0; i < size(); i++ )
2169       if( _nodes[i] == n ) {
2170         map(i,Node_List::pop());
2171         _in_worklist >>= n->_idx;
2172         return;
2173       }
2174     ShouldNotReachHere();
2175   }
2176 }
2177 
2178 //-----------------------remove_useless_nodes----------------------------------
2179 // Remove useless nodes from worklist
2180 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2181 
2182   for( uint i = 0; i < size(); ++i ) {
2183     Node *n = at(i);
2184     assert( n != NULL, "Did not expect null entries in worklist");
2185     if( ! useful.test(n->_idx) ) {
2186       _in_worklist >>= n->_idx;
2187       map(i,Node_List::pop());
2188       // Node *replacement = Node_List::pop();
2189       // if( i != size() ) { // Check if removing last entry
2190       //   _nodes[i] = replacement;
2191       // }
2192       --i;  // Visit popped node
2193       // If it was last entry, loop terminates since size() was also reduced
2194     }
2195   }
2196 }
2197 
2198 //=============================================================================
2199 void Node_Stack::grow() {
2200   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2201   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2202   size_t max = old_max << 1;             // max * 2
2203   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2204   _inode_max = _inodes + max;
2205   _inode_top = _inodes + old_top;        // restore _top
2206 }
2207 
2208 // Node_Stack is used to map nodes.
2209 Node* Node_Stack::find(uint idx) const {
2210   uint sz = size();
2211   for (uint i=0; i < sz; i++) {
2212     if (idx == index_at(i) )
2213       return node_at(i);
2214   }
2215   return NULL;
2216 }
2217 
2218 //=============================================================================
2219 uint TypeNode::size_of() const { return sizeof(*this); }
2220 #ifndef PRODUCT
2221 void TypeNode::dump_spec(outputStream *st) const {
2222   if( !Verbose && !WizardMode ) {
2223     // standard dump does this in Verbose and WizardMode
2224     st->print(" #"); _type->dump_on(st);
2225   }
2226 }
2227 #endif
2228 uint TypeNode::hash() const {
2229   return Node::hash() + _type->hash();
2230 }
2231 uint TypeNode::cmp( const Node &n ) const
2232 { return !Type::cmp( _type, ((TypeNode&)n)._type ); }
2233 const Type *TypeNode::bottom_type() const { return _type; }
2234 const Type *TypeNode::Value( PhaseTransform * ) const { return _type; }
2235 
2236 //------------------------------ideal_reg--------------------------------------
2237 uint TypeNode::ideal_reg() const {
2238   return _type->ideal_reg();
2239 }