1 /*
   2  * Copyright (c) 1997, 2013, 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/machnode.hpp"
  31 #include "opto/matcher.hpp"
  32 #include "opto/node.hpp"
  33 #include "opto/opcodes.hpp"
  34 #include "opto/regmask.hpp"
  35 #include "opto/type.hpp"
  36 #include "utilities/copy.hpp"
  37 
  38 class RegMask;
  39 // #include "phase.hpp"
  40 class PhaseTransform;
  41 class PhaseGVN;
  42 
  43 // Arena we are currently building Nodes in
  44 const uint Node::NotAMachineReg = 0xffff0000;
  45 
  46 #ifndef PRODUCT
  47 extern int nodes_created;
  48 #endif
  49 
  50 #ifdef ASSERT
  51 
  52 //-------------------------- construct_node------------------------------------
  53 // Set a breakpoint here to identify where a particular node index is built.
  54 void Node::verify_construction() {
  55   _debug_orig = NULL;
  56   int old_debug_idx = Compile::debug_idx();
  57   int new_debug_idx = old_debug_idx+1;
  58   if (new_debug_idx > 0) {
  59     // Arrange that the lowest five decimal digits of _debug_idx
  60     // will repeat those of _idx. In case this is somehow pathological,
  61     // we continue to assign negative numbers (!) consecutively.
  62     const int mod = 100000;
  63     int bump = (int)(_idx - new_debug_idx) % mod;
  64     if (bump < 0)  bump += mod;
  65     assert(bump >= 0 && bump < mod, "");
  66     new_debug_idx += bump;
  67   }
  68   Compile::set_debug_idx(new_debug_idx);
  69   set_debug_idx( new_debug_idx );
  70   assert(Compile::current()->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  71   assert(Compile::current()->live_nodes() < (uint)MaxNodeLimit, "Live Node limit exceeded limit");
  72   if (BreakAtNode != 0 && (_debug_idx == BreakAtNode || (int)_idx == BreakAtNode)) {
  73     tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d", _idx, _debug_idx);
  74     BREAKPOINT;
  75   }
  76 #if OPTO_DU_ITERATOR_ASSERT
  77   _last_del = NULL;
  78   _del_tick = 0;
  79 #endif
  80   _hash_lock = 0;
  81 }
  82 
  83 
  84 // #ifdef ASSERT ...
  85 
  86 #if OPTO_DU_ITERATOR_ASSERT
  87 void DUIterator_Common::sample(const Node* node) {
  88   _vdui     = VerifyDUIterators;
  89   _node     = node;
  90   _outcnt   = node->_outcnt;
  91   _del_tick = node->_del_tick;
  92   _last     = NULL;
  93 }
  94 
  95 void DUIterator_Common::verify(const Node* node, bool at_end_ok) {
  96   assert(_node     == node, "consistent iterator source");
  97   assert(_del_tick == node->_del_tick, "no unexpected deletions allowed");
  98 }
  99 
 100 void DUIterator_Common::verify_resync() {
 101   // Ensure that the loop body has just deleted the last guy produced.
 102   const Node* node = _node;
 103   // Ensure that at least one copy of the last-seen edge was deleted.
 104   // Note:  It is OK to delete multiple copies of the last-seen edge.
 105   // Unfortunately, we have no way to verify that all the deletions delete
 106   // that same edge.  On this point we must use the Honor System.
 107   assert(node->_del_tick >= _del_tick+1, "must have deleted an edge");
 108   assert(node->_last_del == _last, "must have deleted the edge just produced");
 109   // We liked this deletion, so accept the resulting outcnt and tick.
 110   _outcnt   = node->_outcnt;
 111   _del_tick = node->_del_tick;
 112 }
 113 
 114 void DUIterator_Common::reset(const DUIterator_Common& that) {
 115   if (this == &that)  return;  // ignore assignment to self
 116   if (!_vdui) {
 117     // We need to initialize everything, overwriting garbage values.
 118     _last = that._last;
 119     _vdui = that._vdui;
 120   }
 121   // Note:  It is legal (though odd) for an iterator over some node x
 122   // to be reassigned to iterate over another node y.  Some doubly-nested
 123   // progress loops depend on being able to do this.
 124   const Node* node = that._node;
 125   // Re-initialize everything, except _last.
 126   _node     = node;
 127   _outcnt   = node->_outcnt;
 128   _del_tick = node->_del_tick;
 129 }
 130 
 131 void DUIterator::sample(const Node* node) {
 132   DUIterator_Common::sample(node);      // Initialize the assertion data.
 133   _refresh_tick = 0;                    // No refreshes have happened, as yet.
 134 }
 135 
 136 void DUIterator::verify(const Node* node, bool at_end_ok) {
 137   DUIterator_Common::verify(node, at_end_ok);
 138   assert(_idx      <  node->_outcnt + (uint)at_end_ok, "idx in range");
 139 }
 140 
 141 void DUIterator::verify_increment() {
 142   if (_refresh_tick & 1) {
 143     // We have refreshed the index during this loop.
 144     // Fix up _idx to meet asserts.
 145     if (_idx > _outcnt)  _idx = _outcnt;
 146   }
 147   verify(_node, true);
 148 }
 149 
 150 void DUIterator::verify_resync() {
 151   // Note:  We do not assert on _outcnt, because insertions are OK here.
 152   DUIterator_Common::verify_resync();
 153   // Make sure we are still in sync, possibly with no more out-edges:
 154   verify(_node, true);
 155 }
 156 
 157 void DUIterator::reset(const DUIterator& that) {
 158   if (this == &that)  return;  // self assignment is always a no-op
 159   assert(that._refresh_tick == 0, "assign only the result of Node::outs()");
 160   assert(that._idx          == 0, "assign only the result of Node::outs()");
 161   assert(_idx               == that._idx, "already assigned _idx");
 162   if (!_vdui) {
 163     // We need to initialize everything, overwriting garbage values.
 164     sample(that._node);
 165   } else {
 166     DUIterator_Common::reset(that);
 167     if (_refresh_tick & 1) {
 168       _refresh_tick++;                  // Clear the "was refreshed" flag.
 169     }
 170     assert(_refresh_tick < 2*100000, "DU iteration must converge quickly");
 171   }
 172 }
 173 
 174 void DUIterator::refresh() {
 175   DUIterator_Common::sample(_node);     // Re-fetch assertion data.
 176   _refresh_tick |= 1;                   // Set the "was refreshed" flag.
 177 }
 178 
 179 void DUIterator::verify_finish() {
 180   // If the loop has killed the node, do not require it to re-run.
 181   if (_node->_outcnt == 0)  _refresh_tick &= ~1;
 182   // If this assert triggers, it means that a loop used refresh_out_pos
 183   // to re-synch an iteration index, but the loop did not correctly
 184   // re-run itself, using a "while (progress)" construct.
 185   // This iterator enforces the rule that you must keep trying the loop
 186   // until it "runs clean" without any need for refreshing.
 187   assert(!(_refresh_tick & 1), "the loop must run once with no refreshing");
 188 }
 189 
 190 
 191 void DUIterator_Fast::verify(const Node* node, bool at_end_ok) {
 192   DUIterator_Common::verify(node, at_end_ok);
 193   Node** out    = node->_out;
 194   uint   cnt    = node->_outcnt;
 195   assert(cnt == _outcnt, "no insertions allowed");
 196   assert(_outp >= out && _outp <= out + cnt - !at_end_ok, "outp in range");
 197   // This last check is carefully designed to work for NO_OUT_ARRAY.
 198 }
 199 
 200 void DUIterator_Fast::verify_limit() {
 201   const Node* node = _node;
 202   verify(node, true);
 203   assert(_outp == node->_out + node->_outcnt, "limit still correct");
 204 }
 205 
 206 void DUIterator_Fast::verify_resync() {
 207   const Node* node = _node;
 208   if (_outp == node->_out + _outcnt) {
 209     // Note that the limit imax, not the pointer i, gets updated with the
 210     // exact count of deletions.  (For the pointer it's always "--i".)
 211     assert(node->_outcnt+node->_del_tick == _outcnt+_del_tick, "no insertions allowed with deletion(s)");
 212     // This is a limit pointer, with a name like "imax".
 213     // Fudge the _last field so that the common assert will be happy.
 214     _last = (Node*) node->_last_del;
 215     DUIterator_Common::verify_resync();
 216   } else {
 217     assert(node->_outcnt < _outcnt, "no insertions allowed with deletion(s)");
 218     // A normal internal pointer.
 219     DUIterator_Common::verify_resync();
 220     // Make sure we are still in sync, possibly with no more out-edges:
 221     verify(node, true);
 222   }
 223 }
 224 
 225 void DUIterator_Fast::verify_relimit(uint n) {
 226   const Node* node = _node;
 227   assert((int)n > 0, "use imax -= n only with a positive count");
 228   // This must be a limit pointer, with a name like "imax".
 229   assert(_outp == node->_out + node->_outcnt, "apply -= only to a limit (imax)");
 230   // The reported number of deletions must match what the node saw.
 231   assert(node->_del_tick == _del_tick + n, "must have deleted n edges");
 232   // Fudge the _last field so that the common assert will be happy.
 233   _last = (Node*) node->_last_del;
 234   DUIterator_Common::verify_resync();
 235 }
 236 
 237 void DUIterator_Fast::reset(const DUIterator_Fast& that) {
 238   assert(_outp              == that._outp, "already assigned _outp");
 239   DUIterator_Common::reset(that);
 240 }
 241 
 242 void DUIterator_Last::verify(const Node* node, bool at_end_ok) {
 243   // at_end_ok means the _outp is allowed to underflow by 1
 244   _outp += at_end_ok;
 245   DUIterator_Fast::verify(node, at_end_ok);  // check _del_tick, etc.
 246   _outp -= at_end_ok;
 247   assert(_outp == (node->_out + node->_outcnt) - 1, "pointer must point to end of nodes");
 248 }
 249 
 250 void DUIterator_Last::verify_limit() {
 251   // Do not require the limit address to be resynched.
 252   //verify(node, true);
 253   assert(_outp == _node->_out, "limit still correct");
 254 }
 255 
 256 void DUIterator_Last::verify_step(uint num_edges) {
 257   assert((int)num_edges > 0, "need non-zero edge count for loop progress");
 258   _outcnt   -= num_edges;
 259   _del_tick += num_edges;
 260   // Make sure we are still in sync, possibly with no more out-edges:
 261   const Node* node = _node;
 262   verify(node, true);
 263   assert(node->_last_del == _last, "must have deleted the edge just produced");
 264 }
 265 
 266 #endif //OPTO_DU_ITERATOR_ASSERT
 267 
 268 
 269 #endif //ASSERT
 270 
 271 
 272 // This constant used to initialize _out may be any non-null value.
 273 // The value NULL is reserved for the top node only.
 274 #define NO_OUT_ARRAY ((Node**)-1)
 275 
 276 // This funny expression handshakes with Node::operator new
 277 // to pull Compile::current out of the new node's _out field,
 278 // and then calls a subroutine which manages most field
 279 // initializations.  The only one which is tricky is the
 280 // _idx field, which is const, and so must be initialized
 281 // by a return value, not an assignment.
 282 //
 283 // (Aren't you thankful that Java finals don't require so many tricks?)
 284 #define IDX_INIT(req) this->Init((req), (Compile*) this->_out)
 285 #ifdef _MSC_VER // the IDX_INIT hack falls foul of warning C4355
 286 #pragma warning( disable:4355 ) // 'this' : used in base member initializer list
 287 #endif
 288 
 289 // Out-of-line code from node constructors.
 290 // Executed only when extra debug info. is being passed around.
 291 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 292   C->set_node_notes_at(idx, nn);
 293 }
 294 
 295 // Shared initialization code.
 296 inline int Node::Init(int req, Compile* C) {
 297   assert(Compile::current() == C, "must use operator new(Compile*)");
 298   int idx = C->next_unique();
 299 
 300   // Allocate memory for the necessary number of edges.
 301   if (req > 0) {
 302     // Allocate space for _in array to have double alignment.
 303     _in = (Node **) ((char *) (C->node_arena()->Amalloc_D(req * sizeof(void*))));
 304 #ifdef ASSERT
 305     _in[req-1] = this; // magic cookie for assertion check
 306 #endif
 307   }
 308   // If there are default notes floating around, capture them:
 309   Node_Notes* nn = C->default_node_notes();
 310   if (nn != NULL)  init_node_notes(C, idx, nn);
 311 
 312   // Note:  At this point, C is dead,
 313   // and we begin to initialize the new Node.
 314 
 315   _cnt = _max = req;
 316   _outcnt = _outmax = 0;
 317   _class_id = Class_Node;
 318   _flags = 0;
 319   _out = NO_OUT_ARRAY;
 320   return idx;
 321 }
 322 
 323 //------------------------------Node-------------------------------------------
 324 // Create a Node, with a given number of required edges.
 325 Node::Node(uint req)
 326   : _idx(IDX_INIT(req))
 327 {
 328   assert( req < (uint)(MaxNodeLimit - NodeLimitFudgeFactor), "Input limit exceeded" );
 329   debug_only( verify_construction() );
 330   NOT_PRODUCT(nodes_created++);
 331   if (req == 0) {
 332     assert( _in == (Node**)this, "Must not pass arg count to 'new'" );
 333     _in = NULL;
 334   } else {
 335     assert( _in[req-1] == this, "Must pass arg count to 'new'" );
 336     Node** to = _in;
 337     for(uint i = 0; i < req; i++) {
 338       to[i] = NULL;
 339     }
 340   }
 341 }
 342 
 343 //------------------------------Node-------------------------------------------
 344 Node::Node(Node *n0)
 345   : _idx(IDX_INIT(1))
 346 {
 347   debug_only( verify_construction() );
 348   NOT_PRODUCT(nodes_created++);
 349   // Assert we allocated space for input array already
 350   assert( _in[0] == this, "Must pass arg count to 'new'" );
 351   assert( is_not_dead(n0), "can not use dead node");
 352   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 353 }
 354 
 355 //------------------------------Node-------------------------------------------
 356 Node::Node(Node *n0, Node *n1)
 357   : _idx(IDX_INIT(2))
 358 {
 359   debug_only( verify_construction() );
 360   NOT_PRODUCT(nodes_created++);
 361   // Assert we allocated space for input array already
 362   assert( _in[1] == this, "Must pass arg count to 'new'" );
 363   assert( is_not_dead(n0), "can not use dead node");
 364   assert( is_not_dead(n1), "can not use dead node");
 365   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 366   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 367 }
 368 
 369 //------------------------------Node-------------------------------------------
 370 Node::Node(Node *n0, Node *n1, Node *n2)
 371   : _idx(IDX_INIT(3))
 372 {
 373   debug_only( verify_construction() );
 374   NOT_PRODUCT(nodes_created++);
 375   // Assert we allocated space for input array already
 376   assert( _in[2] == 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   assert( is_not_dead(n2), "can not use dead node");
 380   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 381   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 382   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 383 }
 384 
 385 //------------------------------Node-------------------------------------------
 386 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 387   : _idx(IDX_INIT(4))
 388 {
 389   debug_only( verify_construction() );
 390   NOT_PRODUCT(nodes_created++);
 391   // Assert we allocated space for input array already
 392   assert( _in[3] == this, "Must pass arg count to 'new'" );
 393   assert( is_not_dead(n0), "can not use dead node");
 394   assert( is_not_dead(n1), "can not use dead node");
 395   assert( is_not_dead(n2), "can not use dead node");
 396   assert( is_not_dead(n3), "can not use dead node");
 397   _in[0] = n0; if (n0 != 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   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 401 }
 402 
 403 //------------------------------Node-------------------------------------------
 404 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 405   : _idx(IDX_INIT(5))
 406 {
 407   debug_only( verify_construction() );
 408   NOT_PRODUCT(nodes_created++);
 409   // Assert we allocated space for input array already
 410   assert( _in[4] == this, "Must pass arg count to 'new'" );
 411   assert( is_not_dead(n0), "can not use dead node");
 412   assert( is_not_dead(n1), "can not use dead node");
 413   assert( is_not_dead(n2), "can not use dead node");
 414   assert( is_not_dead(n3), "can not use dead node");
 415   assert( is_not_dead(n4), "can not use dead node");
 416   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 417   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 418   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 419   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 420   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 421 }
 422 
 423 //------------------------------Node-------------------------------------------
 424 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 425                      Node *n4, Node *n5)
 426   : _idx(IDX_INIT(6))
 427 {
 428   debug_only( verify_construction() );
 429   NOT_PRODUCT(nodes_created++);
 430   // Assert we allocated space for input array already
 431   assert( _in[5] == this, "Must pass arg count to 'new'" );
 432   assert( is_not_dead(n0), "can not use dead node");
 433   assert( is_not_dead(n1), "can not use dead node");
 434   assert( is_not_dead(n2), "can not use dead node");
 435   assert( is_not_dead(n3), "can not use dead node");
 436   assert( is_not_dead(n4), "can not use dead node");
 437   assert( is_not_dead(n5), "can not use dead node");
 438   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 439   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 440   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 441   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 442   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 443   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 444 }
 445 
 446 //------------------------------Node-------------------------------------------
 447 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 448                      Node *n4, Node *n5, Node *n6)
 449   : _idx(IDX_INIT(7))
 450 {
 451   debug_only( verify_construction() );
 452   NOT_PRODUCT(nodes_created++);
 453   // Assert we allocated space for input array already
 454   assert( _in[6] == this, "Must pass arg count to 'new'" );
 455   assert( is_not_dead(n0), "can not use dead node");
 456   assert( is_not_dead(n1), "can not use dead node");
 457   assert( is_not_dead(n2), "can not use dead node");
 458   assert( is_not_dead(n3), "can not use dead node");
 459   assert( is_not_dead(n4), "can not use dead node");
 460   assert( is_not_dead(n5), "can not use dead node");
 461   assert( is_not_dead(n6), "can not use dead node");
 462   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 463   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 464   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 465   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 466   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 467   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 468   _in[6] = n6; if (n6 != NULL) n6->add_out((Node *)this);
 469 }
 470 
 471 
 472 //------------------------------clone------------------------------------------
 473 // Clone a Node.
 474 Node *Node::clone() const {
 475   Compile* C = Compile::current();
 476   uint s = size_of();           // Size of inherited Node
 477   Node *n = (Node*)C->node_arena()->Amalloc_D(size_of() + _max*sizeof(Node*));
 478   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 479   // Set the new input pointer array
 480   n->_in = (Node**)(((char*)n)+s);
 481   // Cannot share the old output pointer array, so kill it
 482   n->_out = NO_OUT_ARRAY;
 483   // And reset the counters to 0
 484   n->_outcnt = 0;
 485   n->_outmax = 0;
 486   // Unlock this guy, since he is not in any hash table.
 487   debug_only(n->_hash_lock = 0);
 488   // Walk the old node's input list to duplicate its edges
 489   uint i;
 490   for( i = 0; i < len(); i++ ) {
 491     Node *x = in(i);
 492     n->_in[i] = x;
 493     if (x != NULL) x->add_out(n);
 494   }
 495   if (is_macro())
 496     C->add_macro_node(n);
 497   if (is_expensive())
 498     C->add_expensive_node(n);
 499 
 500   n->set_idx(C->next_unique()); // Get new unique index as well
 501   debug_only( n->verify_construction() );
 502   NOT_PRODUCT(nodes_created++);
 503   // Do not patch over the debug_idx of a clone, because it makes it
 504   // impossible to break on the clone's moment of creation.
 505   //debug_only( n->set_debug_idx( debug_idx() ) );
 506 
 507   C->copy_node_notes_to(n, (Node*) this);
 508 
 509   // MachNode clone
 510   uint nopnds;
 511   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 512     MachNode *mach  = n->as_Mach();
 513     MachNode *mthis = this->as_Mach();
 514     // Get address of _opnd_array.
 515     // It should be the same offset since it is the clone of this node.
 516     MachOper **from = mthis->_opnds;
 517     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 518                     pointer_delta((const void*)from,
 519                                   (const void*)(&mthis->_opnds), 1));
 520     mach->_opnds = to;
 521     for ( uint i = 0; i < nopnds; ++i ) {
 522       to[i] = from[i]->clone(C);
 523     }
 524   }
 525   // cloning CallNode may need to clone JVMState
 526   if (n->is_Call()) {
 527     n->as_Call()->clone_jvms(C);
 528   }
 529   return n;                     // Return the clone
 530 }
 531 
 532 //---------------------------setup_is_top--------------------------------------
 533 // Call this when changing the top node, to reassert the invariants
 534 // required by Node::is_top.  See Compile::set_cached_top_node.
 535 void Node::setup_is_top() {
 536   if (this == (Node*)Compile::current()->top()) {
 537     // This node has just become top.  Kill its out array.
 538     _outcnt = _outmax = 0;
 539     _out = NULL;                           // marker value for top
 540     assert(is_top(), "must be top");
 541   } else {
 542     if (_out == NULL)  _out = NO_OUT_ARRAY;
 543     assert(!is_top(), "must not be top");
 544   }
 545 }
 546 
 547 
 548 //------------------------------~Node------------------------------------------
 549 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 550 extern int reclaim_idx ;
 551 extern int reclaim_in  ;
 552 extern int reclaim_node;
 553 void Node::destruct() {
 554   // Eagerly reclaim unique Node numberings
 555   Compile* compile = Compile::current();
 556   if ((uint)_idx+1 == compile->unique()) {
 557     compile->set_unique(compile->unique()-1);
 558 #ifdef ASSERT
 559     reclaim_idx++;
 560 #endif
 561   }
 562   // Clear debug info:
 563   Node_Notes* nn = compile->node_notes_at(_idx);
 564   if (nn != NULL)  nn->clear();
 565   // Walk the input array, freeing the corresponding output edges
 566   _cnt = _max;  // forget req/prec distinction
 567   uint i;
 568   for( i = 0; i < _max; i++ ) {
 569     set_req(i, NULL);
 570     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 571   }
 572   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 573   // See if the input array was allocated just prior to the object
 574   int edge_size = _max*sizeof(void*);
 575   int out_edge_size = _outmax*sizeof(void*);
 576   char *edge_end = ((char*)_in) + edge_size;
 577   char *out_array = (char*)(_out == NO_OUT_ARRAY? NULL: _out);
 578   char *out_edge_end = out_array + out_edge_size;
 579   int node_size = size_of();
 580 
 581   // Free the output edge array
 582   if (out_edge_size > 0) {
 583 #ifdef ASSERT
 584     if( out_edge_end == compile->node_arena()->hwm() )
 585       reclaim_in  += out_edge_size;  // count reclaimed out edges with in edges
 586 #endif
 587     compile->node_arena()->Afree(out_array, out_edge_size);
 588   }
 589 
 590   // Free the input edge array and the node itself
 591   if( edge_end == (char*)this ) {
 592 #ifdef ASSERT
 593     if( edge_end+node_size == compile->node_arena()->hwm() ) {
 594       reclaim_in  += edge_size;
 595       reclaim_node+= node_size;
 596     }
 597 #else
 598     // It was; free the input array and object all in one hit
 599     compile->node_arena()->Afree(_in,edge_size+node_size);
 600 #endif
 601   } else {
 602 
 603     // Free just the input array
 604 #ifdef ASSERT
 605     if( edge_end == compile->node_arena()->hwm() )
 606       reclaim_in  += edge_size;
 607 #endif
 608     compile->node_arena()->Afree(_in,edge_size);
 609 
 610     // Free just the object
 611 #ifdef ASSERT
 612     if( ((char*)this) + node_size == compile->node_arena()->hwm() )
 613       reclaim_node+= node_size;
 614 #else
 615     compile->node_arena()->Afree(this,node_size);
 616 #endif
 617   }
 618   if (is_macro()) {
 619     compile->remove_macro_node(this);
 620   }
 621   if (is_expensive()) {
 622     compile->remove_expensive_node(this);
 623   }
 624 #ifdef ASSERT
 625   // We will not actually delete the storage, but we'll make the node unusable.
 626   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 627   _in = _out = (Node**) badAddress;
 628   _max = _cnt = _outmax = _outcnt = 0;
 629 #endif
 630 }
 631 
 632 //------------------------------grow-------------------------------------------
 633 // Grow the input array, making space for more edges
 634 void Node::grow( uint len ) {
 635   Arena* arena = Compile::current()->node_arena();
 636   uint new_max = _max;
 637   if( new_max == 0 ) {
 638     _max = 4;
 639     _in = (Node**)arena->Amalloc(4*sizeof(Node*));
 640     Node** to = _in;
 641     to[0] = NULL;
 642     to[1] = NULL;
 643     to[2] = NULL;
 644     to[3] = NULL;
 645     return;
 646   }
 647   while( new_max <= len ) new_max <<= 1; // Find next power-of-2
 648   // Trimming to limit allows a uint8 to handle up to 255 edges.
 649   // Previously I was using only powers-of-2 which peaked at 128 edges.
 650   //if( new_max >= limit ) new_max = limit-1;
 651   _in = (Node**)arena->Arealloc(_in, _max*sizeof(Node*), new_max*sizeof(Node*));
 652   Copy::zero_to_bytes(&_in[_max], (new_max-_max)*sizeof(Node*)); // NULL all new space
 653   _max = new_max;               // Record new max length
 654   // This assertion makes sure that Node::_max is wide enough to
 655   // represent the numerical value of new_max.
 656   assert(_max == new_max && _max > len, "int width of _max is too small");
 657 }
 658 
 659 //-----------------------------out_grow----------------------------------------
 660 // Grow the input array, making space for more edges
 661 void Node::out_grow( uint len ) {
 662   assert(!is_top(), "cannot grow a top node's out array");
 663   Arena* arena = Compile::current()->node_arena();
 664   uint new_max = _outmax;
 665   if( new_max == 0 ) {
 666     _outmax = 4;
 667     _out = (Node **)arena->Amalloc(4*sizeof(Node*));
 668     return;
 669   }
 670   while( new_max <= len ) new_max <<= 1; // Find next power-of-2
 671   // Trimming to limit allows a uint8 to handle up to 255 edges.
 672   // Previously I was using only powers-of-2 which peaked at 128 edges.
 673   //if( new_max >= limit ) new_max = limit-1;
 674   assert(_out != NULL && _out != NO_OUT_ARRAY, "out must have sensible value");
 675   _out = (Node**)arena->Arealloc(_out,_outmax*sizeof(Node*),new_max*sizeof(Node*));
 676   //Copy::zero_to_bytes(&_out[_outmax], (new_max-_outmax)*sizeof(Node*)); // NULL all new space
 677   _outmax = new_max;               // Record new max length
 678   // This assertion makes sure that Node::_max is wide enough to
 679   // represent the numerical value of new_max.
 680   assert(_outmax == new_max && _outmax > len, "int width of _outmax is too small");
 681 }
 682 
 683 #ifdef ASSERT
 684 //------------------------------is_dead----------------------------------------
 685 bool Node::is_dead() const {
 686   // Mach and pinch point nodes may look like dead.
 687   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 688     return false;
 689   for( uint i = 0; i < _max; i++ )
 690     if( _in[i] != NULL )
 691       return false;
 692   dump();
 693   return true;
 694 }
 695 #endif
 696 
 697 
 698 //------------------------------is_unreachable---------------------------------
 699 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 700   assert(!is_Mach(), "doesn't work with MachNodes");
 701   return outcnt() == 0 || igvn.type(this) == Type::TOP || in(0)->is_top();
 702 }
 703 
 704 //------------------------------add_req----------------------------------------
 705 // Add a new required input at the end
 706 void Node::add_req( Node *n ) {
 707   assert( is_not_dead(n), "can not use dead node");
 708 
 709   // Look to see if I can move precedence down one without reallocating
 710   if( (_cnt >= _max) || (in(_max-1) != NULL) )
 711     grow( _max+1 );
 712 
 713   // Find a precedence edge to move
 714   if( in(_cnt) != NULL ) {       // Next precedence edge is busy?
 715     uint i;
 716     for( i=_cnt; i<_max; i++ )
 717       if( in(i) == NULL )       // Find the NULL at end of prec edge list
 718         break;                  // There must be one, since we grew the array
 719     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 720   }
 721   _in[_cnt++] = n;            // Stuff over old prec edge
 722   if (n != NULL) n->add_out((Node *)this);
 723 }
 724 
 725 //---------------------------add_req_batch-------------------------------------
 726 // Add a new required input at the end
 727 void Node::add_req_batch( Node *n, uint m ) {
 728   assert( is_not_dead(n), "can not use dead node");
 729   // check various edge cases
 730   if ((int)m <= 1) {
 731     assert((int)m >= 0, "oob");
 732     if (m != 0)  add_req(n);
 733     return;
 734   }
 735 
 736   // Look to see if I can move precedence down one without reallocating
 737   if( (_cnt+m) > _max || _in[_max-m] )
 738     grow( _max+m );
 739 
 740   // Find a precedence edge to move
 741   if( _in[_cnt] != NULL ) {     // Next precedence edge is busy?
 742     uint i;
 743     for( i=_cnt; i<_max; i++ )
 744       if( _in[i] == NULL )      // Find the NULL at end of prec edge list
 745         break;                  // There must be one, since we grew the array
 746     // Slide all the precs over by m positions (assume #prec << m).
 747     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 748   }
 749 
 750   // Stuff over the old prec edges
 751   for(uint i=0; i<m; i++ ) {
 752     _in[_cnt++] = n;
 753   }
 754 
 755   // Insert multiple out edges on the node.
 756   if (n != NULL && !n->is_top()) {
 757     for(uint i=0; i<m; i++ ) {
 758       n->add_out((Node *)this);
 759     }
 760   }
 761 }
 762 
 763 //------------------------------del_req----------------------------------------
 764 // Delete the required edge and compact the edge array
 765 void Node::del_req( uint idx ) {
 766   assert( idx < _cnt, "oob");
 767   assert( !VerifyHashTableKeys || _hash_lock == 0,
 768           "remove node from hash table before modifying it");
 769   // First remove corresponding def-use edge
 770   Node *n = in(idx);
 771   if (n != NULL) n->del_out((Node *)this);
 772   _in[idx] = in(--_cnt);  // Compact the array
 773   _in[_cnt] = NULL;       // NULL out emptied slot
 774 }
 775 
 776 //------------------------------del_req_ordered--------------------------------
 777 // Delete the required edge and compact the edge array with preserved order
 778 void Node::del_req_ordered( uint idx ) {
 779   assert( idx < _cnt, "oob");
 780   assert( !VerifyHashTableKeys || _hash_lock == 0,
 781           "remove node from hash table before modifying it");
 782   // First remove corresponding def-use edge
 783   Node *n = in(idx);
 784   if (n != NULL) n->del_out((Node *)this);
 785   if (idx < _cnt - 1) { // Not last edge ?
 786     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx-1)*sizeof(Node*)));
 787   }
 788   _in[--_cnt] = NULL;   // NULL out emptied slot
 789 }
 790 
 791 //------------------------------ins_req----------------------------------------
 792 // Insert a new required input at the end
 793 void Node::ins_req( uint idx, Node *n ) {
 794   assert( is_not_dead(n), "can not use dead node");
 795   add_req(NULL);                // Make space
 796   assert( idx < _max, "Must have allocated enough space");
 797   // Slide over
 798   if(_cnt-idx-1 > 0) {
 799     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 800   }
 801   _in[idx] = n;                            // Stuff over old required edge
 802   if (n != NULL) n->add_out((Node *)this); // Add reciprocal def-use edge
 803 }
 804 
 805 //-----------------------------find_edge---------------------------------------
 806 int Node::find_edge(Node* n) {
 807   for (uint i = 0; i < len(); i++) {
 808     if (_in[i] == n)  return i;
 809   }
 810   return -1;
 811 }
 812 
 813 //----------------------------replace_edge-------------------------------------
 814 int Node::replace_edge(Node* old, Node* neww) {
 815   if (old == neww)  return 0;  // nothing to do
 816   uint nrep = 0;
 817   for (uint i = 0; i < len(); i++) {
 818     if (in(i) == old) {
 819       if (i < req())
 820         set_req(i, neww);
 821       else
 822         set_prec(i, neww);
 823       nrep++;
 824     }
 825   }
 826   return nrep;
 827 }
 828 
 829 /**
 830  * Replace input edges in the range pointing to 'old' node.
 831  */
 832 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end) {
 833   if (old == neww)  return 0;  // nothing to do
 834   uint nrep = 0;
 835   for (int i = start; i < end; i++) {
 836     if (in(i) == old) {
 837       set_req(i, neww);
 838       nrep++;
 839     }
 840   }
 841   return nrep;
 842 }
 843 
 844 //-------------------------disconnect_inputs-----------------------------------
 845 // NULL out all inputs to eliminate incoming Def-Use edges.
 846 // Return the number of edges between 'n' and 'this'
 847 int Node::disconnect_inputs(Node *n, Compile* C) {
 848   int edges_to_n = 0;
 849 
 850   uint cnt = req();
 851   for( uint i = 0; i < cnt; ++i ) {
 852     if( in(i) == 0 ) continue;
 853     if( in(i) == n ) ++edges_to_n;
 854     set_req(i, NULL);
 855   }
 856   // Remove precedence edges if any exist
 857   // Note: Safepoints may have precedence edges, even during parsing
 858   if( (req() != len()) && (in(req()) != NULL) ) {
 859     uint max = len();
 860     for( uint i = 0; i < max; ++i ) {
 861       if( in(i) == 0 ) continue;
 862       if( in(i) == n ) ++edges_to_n;
 863       set_prec(i, NULL);
 864     }
 865   }
 866 
 867   // Node::destruct requires all out edges be deleted first
 868   // debug_only(destruct();)   // no reuse benefit expected
 869   if (edges_to_n == 0) {
 870     C->record_dead_node(_idx);
 871   }
 872   return edges_to_n;
 873 }
 874 
 875 //-----------------------------uncast---------------------------------------
 876 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 877 // Strip away casting.  (It is depth-limited.)
 878 Node* Node::uncast() const {
 879   // Should be inline:
 880   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 881   if (is_ConstraintCast() || is_CheckCastPP())
 882     return uncast_helper(this);
 883   else
 884     return (Node*) this;
 885 }
 886 
 887 //---------------------------uncast_helper-------------------------------------
 888 Node* Node::uncast_helper(const Node* p) {
 889 #ifdef ASSERT
 890   uint depth_count = 0;
 891   const Node* orig_p = p;
 892 #endif
 893 
 894   while (true) {
 895 #ifdef ASSERT
 896     if (depth_count >= K) {
 897       orig_p->dump(4);
 898       if (p != orig_p)
 899         p->dump(1);
 900     }
 901     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
 902 #endif
 903     if (p == NULL || p->req() != 2) {
 904       break;
 905     } else if (p->is_ConstraintCast()) {
 906       p = p->in(1);
 907     } else if (p->is_CheckCastPP()) {
 908       p = p->in(1);
 909     } else {
 910       break;
 911     }
 912   }
 913   return (Node*) p;
 914 }
 915 
 916 //------------------------------add_prec---------------------------------------
 917 // Add a new precedence input.  Precedence inputs are unordered, with
 918 // duplicates removed and NULLs packed down at the end.
 919 void Node::add_prec( Node *n ) {
 920   assert( is_not_dead(n), "can not use dead node");
 921 
 922   // Check for NULL at end
 923   if( _cnt >= _max || in(_max-1) )
 924     grow( _max+1 );
 925 
 926   // Find a precedence edge to move
 927   uint i = _cnt;
 928   while( in(i) != NULL ) i++;
 929   _in[i] = n;                                // Stuff prec edge over NULL
 930   if ( n != NULL) n->add_out((Node *)this);  // Add mirror edge
 931 }
 932 
 933 //------------------------------rm_prec----------------------------------------
 934 // Remove a precedence input.  Precedence inputs are unordered, with
 935 // duplicates removed and NULLs packed down at the end.
 936 void Node::rm_prec( uint j ) {
 937 
 938   // Find end of precedence list to pack NULLs
 939   uint i;
 940   for( i=j; i<_max; i++ )
 941     if( !_in[i] )               // Find the NULL at end of prec edge list
 942       break;
 943   if (_in[j] != NULL) _in[j]->del_out((Node *)this);
 944   _in[j] = _in[--i];            // Move last element over removed guy
 945   _in[i] = NULL;                // NULL out last element
 946 }
 947 
 948 //------------------------------size_of----------------------------------------
 949 uint Node::size_of() const { return sizeof(*this); }
 950 
 951 //------------------------------ideal_reg--------------------------------------
 952 uint Node::ideal_reg() const { return 0; }
 953 
 954 //------------------------------jvms-------------------------------------------
 955 JVMState* Node::jvms() const { return NULL; }
 956 
 957 #ifdef ASSERT
 958 //------------------------------jvms-------------------------------------------
 959 bool Node::verify_jvms(const JVMState* using_jvms) const {
 960   for (JVMState* jvms = this->jvms(); jvms != NULL; jvms = jvms->caller()) {
 961     if (jvms == using_jvms)  return true;
 962   }
 963   return false;
 964 }
 965 
 966 //------------------------------init_NodeProperty------------------------------
 967 void Node::init_NodeProperty() {
 968   assert(_max_classes <= max_jushort, "too many NodeProperty classes");
 969   assert(_max_flags <= max_jushort, "too many NodeProperty flags");
 970 }
 971 #endif
 972 
 973 //------------------------------format-----------------------------------------
 974 // Print as assembly
 975 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
 976 //------------------------------emit-------------------------------------------
 977 // Emit bytes starting at parameter 'ptr'.
 978 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
 979 //------------------------------size-------------------------------------------
 980 // Size of instruction in bytes
 981 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
 982 
 983 //------------------------------CFG Construction-------------------------------
 984 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
 985 // Goto and Return.
 986 const Node *Node::is_block_proj() const { return 0; }
 987 
 988 // Minimum guaranteed type
 989 const Type *Node::bottom_type() const { return Type::BOTTOM; }
 990 
 991 
 992 //------------------------------raise_bottom_type------------------------------
 993 // Get the worst-case Type output for this Node.
 994 void Node::raise_bottom_type(const Type* new_type) {
 995   if (is_Type()) {
 996     TypeNode *n = this->as_Type();
 997     if (VerifyAliases) {
 998       assert(new_type->higher_equal(n->type()), "new type must refine old type");
 999     }
1000     n->set_type(new_type);
1001   } else if (is_Load()) {
1002     LoadNode *n = this->as_Load();
1003     if (VerifyAliases) {
1004       assert(new_type->higher_equal(n->type()), "new type must refine old type");
1005     }
1006     n->set_type(new_type);
1007   }
1008 }
1009 
1010 //------------------------------Identity---------------------------------------
1011 // Return a node that the given node is equivalent to.
1012 Node *Node::Identity( PhaseTransform * ) {
1013   return this;                  // Default to no identities
1014 }
1015 
1016 //------------------------------Value------------------------------------------
1017 // Compute a new Type for a node using the Type of the inputs.
1018 const Type *Node::Value( PhaseTransform * ) const {
1019   return bottom_type();         // Default to worst-case Type
1020 }
1021 
1022 //------------------------------Ideal------------------------------------------
1023 //
1024 // 'Idealize' the graph rooted at this Node.
1025 //
1026 // In order to be efficient and flexible there are some subtle invariants
1027 // these Ideal calls need to hold.  Running with '+VerifyIterativeGVN' checks
1028 // these invariants, although its too slow to have on by default.  If you are
1029 // hacking an Ideal call, be sure to test with +VerifyIterativeGVN!
1030 //
1031 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1032 // pointer.  If ANY change is made, it must return the root of the reshaped
1033 // graph - even if the root is the same Node.  Example: swapping the inputs
1034 // to an AddINode gives the same answer and same root, but you still have to
1035 // return the 'this' pointer instead of NULL.
1036 //
1037 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1038 // Identity call to return an old Node; basically if Identity can find
1039 // another Node have the Ideal call make no change and return NULL.
1040 // Example: AddINode::Ideal must check for add of zero; in this case it
1041 // returns NULL instead of doing any graph reshaping.
1042 //
1043 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1044 // sharing there may be other users of the old Nodes relying on their current
1045 // semantics.  Modifying them will break the other users.
1046 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1047 // "X+3" unchanged in case it is shared.
1048 //
1049 // If you modify the 'this' pointer's inputs, you should use
1050 // 'set_req'.  If you are making a new Node (either as the new root or
1051 // some new internal piece) you may use 'init_req' to set the initial
1052 // value.  You can make a new Node with either 'new' or 'clone'.  In
1053 // either case, def-use info is correctly maintained.
1054 //
1055 // Example: reshape "(X+3)+4" into "X+7":
1056 //    set_req(1, in(1)->in(1));
1057 //    set_req(2, phase->intcon(7));
1058 //    return this;
1059 // Example: reshape "X*4" into "X<<2"
1060 //    return new (C) LShiftINode(in(1), phase->intcon(2));
1061 //
1062 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1063 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1064 //    Node *shift=phase->transform(new(C)LShiftINode(in(1),phase->intcon(5)));
1065 //    return new (C) AddINode(shift, in(1));
1066 //
1067 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1068 // These forms are faster than 'phase->transform(new (C) ConNode())' and Do
1069 // The Right Thing with def-use info.
1070 //
1071 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1072 // graph uses the 'this' Node it must be the root.  If you want a Node with
1073 // the same Opcode as the 'this' pointer use 'clone'.
1074 //
1075 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1076   return NULL;                  // Default to being Ideal already
1077 }
1078 
1079 // Some nodes have specific Ideal subgraph transformations only if they are
1080 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1081 // for the transformations to happen.
1082 bool Node::has_special_unique_user() const {
1083   assert(outcnt() == 1, "match only for unique out");
1084   Node* n = unique_out();
1085   int op  = Opcode();
1086   if( this->is_Store() ) {
1087     // Condition for back-to-back stores folding.
1088     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1089   } else if( op == Op_AddL ) {
1090     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1091     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1092   } else if( op == Op_SubI || op == Op_SubL ) {
1093     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1094     return n->Opcode() == op && n->in(2) == this;
1095   }
1096   return false;
1097 };
1098 
1099 //--------------------------find_exact_control---------------------------------
1100 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1101 Node* Node::find_exact_control(Node* ctrl) {
1102   if (ctrl == NULL && this->is_Region())
1103     ctrl = this->as_Region()->is_copy();
1104 
1105   if (ctrl != NULL && ctrl->is_CatchProj()) {
1106     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1107       ctrl = ctrl->in(0);
1108     if (ctrl != NULL && !ctrl->is_top())
1109       ctrl = ctrl->in(0);
1110   }
1111 
1112   if (ctrl != NULL && ctrl->is_Proj())
1113     ctrl = ctrl->in(0);
1114 
1115   return ctrl;
1116 }
1117 
1118 //--------------------------dominates------------------------------------------
1119 // Helper function for MemNode::all_controls_dominate().
1120 // Check if 'this' control node dominates or equal to 'sub' control node.
1121 // We already know that if any path back to Root or Start reaches 'this',
1122 // then all paths so, so this is a simple search for one example,
1123 // not an exhaustive search for a counterexample.
1124 bool Node::dominates(Node* sub, Node_List &nlist) {
1125   assert(this->is_CFG(), "expecting control");
1126   assert(sub != NULL && sub->is_CFG(), "expecting control");
1127 
1128   // detect dead cycle without regions
1129   int iterations_without_region_limit = DominatorSearchLimit;
1130 
1131   Node* orig_sub = sub;
1132   Node* dom      = this;
1133   bool  met_dom  = false;
1134   nlist.clear();
1135 
1136   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1137   // After seeing 'dom', continue up to Root or Start.
1138   // If we hit a region (backward split point), it may be a loop head.
1139   // Keep going through one of the region's inputs.  If we reach the
1140   // same region again, go through a different input.  Eventually we
1141   // will either exit through the loop head, or give up.
1142   // (If we get confused, break out and return a conservative 'false'.)
1143   while (sub != NULL) {
1144     if (sub->is_top())  break; // Conservative answer for dead code.
1145     if (sub == dom) {
1146       if (nlist.size() == 0) {
1147         // No Region nodes except loops were visited before and the EntryControl
1148         // path was taken for loops: it did not walk in a cycle.
1149         return true;
1150       } else if (met_dom) {
1151         break;          // already met before: walk in a cycle
1152       } else {
1153         // Region nodes were visited. Continue walk up to Start or Root
1154         // to make sure that it did not walk in a cycle.
1155         met_dom = true; // first time meet
1156         iterations_without_region_limit = DominatorSearchLimit; // Reset
1157      }
1158     }
1159     if (sub->is_Start() || sub->is_Root()) {
1160       // Success if we met 'dom' along a path to Start or Root.
1161       // We assume there are no alternative paths that avoid 'dom'.
1162       // (This assumption is up to the caller to ensure!)
1163       return met_dom;
1164     }
1165     Node* up = sub->in(0);
1166     // Normalize simple pass-through regions and projections:
1167     up = sub->find_exact_control(up);
1168     // If sub == up, we found a self-loop.  Try to push past it.
1169     if (sub == up && sub->is_Loop()) {
1170       // Take loop entry path on the way up to 'dom'.
1171       up = sub->in(1); // in(LoopNode::EntryControl);
1172     } else if (sub == up && sub->is_Region() && sub->req() != 3) {
1173       // Always take in(1) path on the way up to 'dom' for clone regions
1174       // (with only one input) or regions which merge > 2 paths
1175       // (usually used to merge fast/slow paths).
1176       up = sub->in(1);
1177     } else if (sub == up && sub->is_Region()) {
1178       // Try both paths for Regions with 2 input paths (it may be a loop head).
1179       // It could give conservative 'false' answer without information
1180       // which region's input is the entry path.
1181       iterations_without_region_limit = DominatorSearchLimit; // Reset
1182 
1183       bool region_was_visited_before = false;
1184       // Was this Region node visited before?
1185       // If so, we have reached it because we accidentally took a
1186       // loop-back edge from 'sub' back into the body of the loop,
1187       // and worked our way up again to the loop header 'sub'.
1188       // So, take the first unexplored path on the way up to 'dom'.
1189       for (int j = nlist.size() - 1; j >= 0; j--) {
1190         intptr_t ni = (intptr_t)nlist.at(j);
1191         Node* visited = (Node*)(ni & ~1);
1192         bool  visited_twice_already = ((ni & 1) != 0);
1193         if (visited == sub) {
1194           if (visited_twice_already) {
1195             // Visited 2 paths, but still stuck in loop body.  Give up.
1196             return false;
1197           }
1198           // The Region node was visited before only once.
1199           // (We will repush with the low bit set, below.)
1200           nlist.remove(j);
1201           // We will find a new edge and re-insert.
1202           region_was_visited_before = true;
1203           break;
1204         }
1205       }
1206 
1207       // Find an incoming edge which has not been seen yet; walk through it.
1208       assert(up == sub, "");
1209       uint skip = region_was_visited_before ? 1 : 0;
1210       for (uint i = 1; i < sub->req(); i++) {
1211         Node* in = sub->in(i);
1212         if (in != NULL && !in->is_top() && in != sub) {
1213           if (skip == 0) {
1214             up = in;
1215             break;
1216           }
1217           --skip;               // skip this nontrivial input
1218         }
1219       }
1220 
1221       // Set 0 bit to indicate that both paths were taken.
1222       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1223     }
1224 
1225     if (up == sub) {
1226       break;    // some kind of tight cycle
1227     }
1228     if (up == orig_sub && met_dom) {
1229       // returned back after visiting 'dom'
1230       break;    // some kind of cycle
1231     }
1232     if (--iterations_without_region_limit < 0) {
1233       break;    // dead cycle
1234     }
1235     sub = up;
1236   }
1237 
1238   // Did not meet Root or Start node in pred. chain.
1239   // Conservative answer for dead code.
1240   return false;
1241 }
1242 
1243 //------------------------------remove_dead_region-----------------------------
1244 // This control node is dead.  Follow the subgraph below it making everything
1245 // using it dead as well.  This will happen normally via the usual IterGVN
1246 // worklist but this call is more efficient.  Do not update use-def info
1247 // inside the dead region, just at the borders.
1248 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1249   // Con's are a popular node to re-hit in the hash table again.
1250   if( dead->is_Con() ) return;
1251 
1252   // Can't put ResourceMark here since igvn->_worklist uses the same arena
1253   // for verify pass with +VerifyOpto and we add/remove elements in it here.
1254   Node_List  nstack(Thread::current()->resource_area());
1255 
1256   Node *top = igvn->C->top();
1257   nstack.push(dead);
1258 
1259   while (nstack.size() > 0) {
1260     dead = nstack.pop();
1261     if (dead->outcnt() > 0) {
1262       // Keep dead node on stack until all uses are processed.
1263       nstack.push(dead);
1264       // For all Users of the Dead...    ;-)
1265       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1266         Node* use = dead->last_out(k);
1267         igvn->hash_delete(use);       // Yank from hash table prior to mod
1268         if (use->in(0) == dead) {     // Found another dead node
1269           assert (!use->is_Con(), "Control for Con node should be Root node.");
1270           use->set_req(0, top);       // Cut dead edge to prevent processing
1271           nstack.push(use);           // the dead node again.
1272         } else {                      // Else found a not-dead user
1273           for (uint j = 1; j < use->req(); j++) {
1274             if (use->in(j) == dead) { // Turn all dead inputs into TOP
1275               use->set_req(j, top);
1276             }
1277           }
1278           igvn->_worklist.push(use);
1279         }
1280         // Refresh the iterator, since any number of kills might have happened.
1281         k = dead->last_outs(kmin);
1282       }
1283     } else { // (dead->outcnt() == 0)
1284       // Done with outputs.
1285       igvn->hash_delete(dead);
1286       igvn->_worklist.remove(dead);
1287       igvn->set_type(dead, Type::TOP);
1288       if (dead->is_macro()) {
1289         igvn->C->remove_macro_node(dead);
1290       }
1291       if (dead->is_expensive()) {
1292         igvn->C->remove_expensive_node(dead);
1293       }
1294       igvn->C->record_dead_node(dead->_idx);
1295       // Kill all inputs to the dead guy
1296       for (uint i=0; i < dead->req(); i++) {
1297         Node *n = dead->in(i);      // Get input to dead guy
1298         if (n != NULL && !n->is_top()) { // Input is valid?
1299           dead->set_req(i, top);    // Smash input away
1300           if (n->outcnt() == 0) {   // Input also goes dead?
1301             if (!n->is_Con())
1302               nstack.push(n);       // Clear it out as well
1303           } else if (n->outcnt() == 1 &&
1304                      n->has_special_unique_user()) {
1305             igvn->add_users_to_worklist( n );
1306           } else if (n->outcnt() <= 2 && n->is_Store()) {
1307             // Push store's uses on worklist to enable folding optimization for
1308             // store/store and store/load to the same address.
1309             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1310             // and remove_globally_dead_node().
1311             igvn->add_users_to_worklist( n );
1312           }
1313         }
1314       }
1315     } // (dead->outcnt() == 0)
1316   }   // while (nstack.size() > 0) for outputs
1317   return;
1318 }
1319 
1320 //------------------------------remove_dead_region-----------------------------
1321 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1322   Node *n = in(0);
1323   if( !n ) return false;
1324   // Lost control into this guy?  I.e., it became unreachable?
1325   // Aggressively kill all unreachable code.
1326   if (can_reshape && n->is_top()) {
1327     kill_dead_code(this, phase->is_IterGVN());
1328     return false; // Node is dead.
1329   }
1330 
1331   if( n->is_Region() && n->as_Region()->is_copy() ) {
1332     Node *m = n->nonnull_req();
1333     set_req(0, m);
1334     return true;
1335   }
1336   return false;
1337 }
1338 
1339 //------------------------------Ideal_DU_postCCP-------------------------------
1340 // Idealize graph, using DU info.  Must clone result into new-space
1341 Node *Node::Ideal_DU_postCCP( PhaseCCP * ) {
1342   return NULL;                 // Default to no change
1343 }
1344 
1345 //------------------------------hash-------------------------------------------
1346 // Hash function over Nodes.
1347 uint Node::hash() const {
1348   uint sum = 0;
1349   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1350     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded NULLs
1351   return (sum>>2) + _cnt + Opcode();
1352 }
1353 
1354 //------------------------------cmp--------------------------------------------
1355 // Compare special parts of simple Nodes
1356 uint Node::cmp( const Node &n ) const {
1357   return 1;                     // Must be same
1358 }
1359 
1360 //------------------------------rematerialize-----------------------------------
1361 // Should we clone rather than spill this instruction?
1362 bool Node::rematerialize() const {
1363   if ( is_Mach() )
1364     return this->as_Mach()->rematerialize();
1365   else
1366     return (_flags & Flag_rematerialize) != 0;
1367 }
1368 
1369 //------------------------------needs_anti_dependence_check---------------------
1370 // Nodes which use memory without consuming it, hence need antidependences.
1371 bool Node::needs_anti_dependence_check() const {
1372   if( req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0 )
1373     return false;
1374   else
1375     return in(1)->bottom_type()->has_memory();
1376 }
1377 
1378 
1379 // Get an integer constant from a ConNode (or CastIINode).
1380 // Return a default value if there is no apparent constant here.
1381 const TypeInt* Node::find_int_type() const {
1382   if (this->is_Type()) {
1383     return this->as_Type()->type()->isa_int();
1384   } else if (this->is_Con()) {
1385     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1386     return this->bottom_type()->isa_int();
1387   }
1388   return NULL;
1389 }
1390 
1391 // Get a pointer constant from a ConstNode.
1392 // Returns the constant if it is a pointer ConstNode
1393 intptr_t Node::get_ptr() const {
1394   assert( Opcode() == Op_ConP, "" );
1395   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1396 }
1397 
1398 // Get a narrow oop constant from a ConNNode.
1399 intptr_t Node::get_narrowcon() const {
1400   assert( Opcode() == Op_ConN, "" );
1401   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1402 }
1403 
1404 // Get a long constant from a ConNode.
1405 // Return a default value if there is no apparent constant here.
1406 const TypeLong* Node::find_long_type() const {
1407   if (this->is_Type()) {
1408     return this->as_Type()->type()->isa_long();
1409   } else if (this->is_Con()) {
1410     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1411     return this->bottom_type()->isa_long();
1412   }
1413   return NULL;
1414 }
1415 
1416 
1417 /**
1418  * Return a ptr type for nodes which should have it.
1419  */
1420 const TypePtr* Node::get_ptr_type() const {
1421   const TypePtr* tp = this->bottom_type()->make_ptr();
1422 #ifdef ASSERT
1423   if (tp == NULL) {
1424     this->dump(1);
1425     assert((tp != NULL), "unexpected node type");
1426   }
1427 #endif
1428   return tp;
1429 }
1430 
1431 // Get a double constant from a ConstNode.
1432 // Returns the constant if it is a double ConstNode
1433 jdouble Node::getd() const {
1434   assert( Opcode() == Op_ConD, "" );
1435   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1436 }
1437 
1438 // Get a float constant from a ConstNode.
1439 // Returns the constant if it is a float ConstNode
1440 jfloat Node::getf() const {
1441   assert( Opcode() == Op_ConF, "" );
1442   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1443 }
1444 
1445 #ifndef PRODUCT
1446 
1447 //----------------------------NotANode----------------------------------------
1448 // Used in debugging code to avoid walking across dead or uninitialized edges.
1449 static inline bool NotANode(const Node* n) {
1450   if (n == NULL)                   return true;
1451   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
1452   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
1453   return false;
1454 }
1455 
1456 
1457 //------------------------------find------------------------------------------
1458 // Find a neighbor of this Node with the given _idx
1459 // If idx is negative, find its absolute value, following both _in and _out.
1460 static void find_recur(Compile* C,  Node* &result, Node *n, int idx, bool only_ctrl,
1461                         VectorSet* old_space, VectorSet* new_space ) {
1462   int node_idx = (idx >= 0) ? idx : -idx;
1463   if (NotANode(n))  return;  // Gracefully handle NULL, -1, 0xabababab, etc.
1464   // Contained in new_space or old_space?   Check old_arena first since it's mostly empty.
1465   VectorSet *v = C->old_arena()->contains(n) ? old_space : new_space;
1466   if( v->test(n->_idx) ) return;
1467   if( (int)n->_idx == node_idx
1468       debug_only(|| n->debug_idx() == node_idx) ) {
1469     if (result != NULL)
1470       tty->print("find: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1471                  (uintptr_t)result, (uintptr_t)n, node_idx);
1472     result = n;
1473   }
1474   v->set(n->_idx);
1475   for( uint i=0; i<n->len(); i++ ) {
1476     if( only_ctrl && !(n->is_Region()) && (n->Opcode() != Op_Root) && (i != TypeFunc::Control) ) continue;
1477     find_recur(C, result, n->in(i), idx, only_ctrl, old_space, new_space );
1478   }
1479   // Search along forward edges also:
1480   if (idx < 0 && !only_ctrl) {
1481     for( uint j=0; j<n->outcnt(); j++ ) {
1482       find_recur(C, result, n->raw_out(j), idx, only_ctrl, old_space, new_space );
1483     }
1484   }
1485 #ifdef ASSERT
1486   // Search along debug_orig edges last, checking for cycles
1487   Node* orig = n->debug_orig();
1488   if (orig != NULL) {
1489     do {
1490       if (NotANode(orig))  break;
1491       find_recur(C, result, orig, idx, only_ctrl, old_space, new_space );
1492       orig = orig->debug_orig();
1493     } while (orig != NULL && orig != n->debug_orig());
1494   }
1495 #endif //ASSERT
1496 }
1497 
1498 // call this from debugger:
1499 Node* find_node(Node* n, int idx) {
1500   return n->find(idx);
1501 }
1502 
1503 //------------------------------find-------------------------------------------
1504 Node* Node::find(int idx) const {
1505   ResourceArea *area = Thread::current()->resource_area();
1506   VectorSet old_space(area), new_space(area);
1507   Node* result = NULL;
1508   find_recur(Compile::current(), result, (Node*) this, idx, false, &old_space, &new_space );
1509   return result;
1510 }
1511 
1512 //------------------------------find_ctrl--------------------------------------
1513 // Find an ancestor to this node in the control history with given _idx
1514 Node* Node::find_ctrl(int idx) const {
1515   ResourceArea *area = Thread::current()->resource_area();
1516   VectorSet old_space(area), new_space(area);
1517   Node* result = NULL;
1518   find_recur(Compile::current(), result, (Node*) this, idx, true, &old_space, &new_space );
1519   return result;
1520 }
1521 #endif
1522 
1523 
1524 
1525 #ifndef PRODUCT
1526 int Node::_in_dump_cnt = 0;
1527 
1528 // -----------------------------Name-------------------------------------------
1529 extern const char *NodeClassNames[];
1530 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
1531 
1532 static bool is_disconnected(const Node* n) {
1533   for (uint i = 0; i < n->req(); i++) {
1534     if (n->in(i) != NULL)  return false;
1535   }
1536   return true;
1537 }
1538 
1539 #ifdef ASSERT
1540 static void dump_orig(Node* orig, outputStream *st) {
1541   Compile* C = Compile::current();
1542   if (NotANode(orig)) orig = NULL;
1543   if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1544   if (orig == NULL) return;
1545   st->print(" !orig=");
1546   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
1547   if (NotANode(fast)) fast = NULL;
1548   while (orig != NULL) {
1549     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
1550     if (discon) st->print("[");
1551     if (!Compile::current()->node_arena()->contains(orig))
1552       st->print("o");
1553     st->print("%d", orig->_idx);
1554     if (discon) st->print("]");
1555     orig = orig->debug_orig();
1556     if (NotANode(orig)) orig = NULL;
1557     if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1558     if (orig != NULL) st->print(",");
1559     if (fast != NULL) {
1560       // Step fast twice for each single step of orig:
1561       fast = fast->debug_orig();
1562       if (NotANode(fast)) fast = NULL;
1563       if (fast != NULL && fast != orig) {
1564         fast = fast->debug_orig();
1565         if (NotANode(fast)) fast = NULL;
1566       }
1567       if (fast == orig) {
1568         st->print("...");
1569         break;
1570       }
1571     }
1572   }
1573 }
1574 
1575 void Node::set_debug_orig(Node* orig) {
1576   _debug_orig = orig;
1577   if (BreakAtNode == 0)  return;
1578   if (NotANode(orig))  orig = NULL;
1579   int trip = 10;
1580   while (orig != NULL) {
1581     if (orig->debug_idx() == BreakAtNode || (int)orig->_idx == BreakAtNode) {
1582       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d orig._idx=%d orig._debug_idx=%d",
1583                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
1584       BREAKPOINT;
1585     }
1586     orig = orig->debug_orig();
1587     if (NotANode(orig))  orig = NULL;
1588     if (trip-- <= 0)  break;
1589   }
1590 }
1591 #endif //ASSERT
1592 
1593 //------------------------------dump------------------------------------------
1594 // Dump a Node
1595 void Node::dump(const char* suffix, outputStream *st) const {
1596   Compile* C = Compile::current();
1597   bool is_new = C->node_arena()->contains(this);
1598   _in_dump_cnt++;
1599   st->print("%c%d\t%s\t=== ", is_new ? ' ' : 'o', _idx, Name());
1600 
1601   // Dump the required and precedence inputs
1602   dump_req(st);
1603   dump_prec(st);
1604   // Dump the outputs
1605   dump_out(st);
1606 
1607   if (is_disconnected(this)) {
1608 #ifdef ASSERT
1609     st->print("  [%d]",debug_idx());
1610     dump_orig(debug_orig(), st);
1611 #endif
1612     st->cr();
1613     _in_dump_cnt--;
1614     return;                     // don't process dead nodes
1615   }
1616 
1617   // Dump node-specific info
1618   dump_spec(st);
1619 #ifdef ASSERT
1620   // Dump the non-reset _debug_idx
1621   if (Verbose && WizardMode) {
1622     st->print("  [%d]",debug_idx());
1623   }
1624 #endif
1625 
1626   const Type *t = bottom_type();
1627 
1628   if (t != NULL && (t->isa_instptr() || t->isa_klassptr())) {
1629     const TypeInstPtr  *toop = t->isa_instptr();
1630     const TypeKlassPtr *tkls = t->isa_klassptr();
1631     ciKlass*           klass = toop ? toop->klass() : (tkls ? tkls->klass() : NULL );
1632     if (klass && klass->is_loaded() && klass->is_interface()) {
1633       st->print("  Interface:");
1634     } else if (toop) {
1635       st->print("  Oop:");
1636     } else if (tkls) {
1637       st->print("  Klass:");
1638     }
1639     t->dump_on(st);
1640   } else if (t == Type::MEMORY) {
1641     st->print("  Memory:");
1642     MemNode::dump_adr_type(this, adr_type(), st);
1643   } else if (Verbose || WizardMode) {
1644     st->print("  Type:");
1645     if (t) {
1646       t->dump_on(st);
1647     } else {
1648       st->print("no type");
1649     }
1650   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
1651     // Dump MachSpillcopy vector type.
1652     t->dump_on(st);
1653   }
1654   if (is_new) {
1655     debug_only(dump_orig(debug_orig(), st));
1656     Node_Notes* nn = C->node_notes_at(_idx);
1657     if (nn != NULL && !nn->is_clear()) {
1658       if (nn->jvms() != NULL) {
1659         st->print(" !jvms:");
1660         nn->jvms()->dump_spec(st);
1661       }
1662     }
1663   }
1664   if (suffix) st->print(suffix);
1665   _in_dump_cnt--;
1666 }
1667 
1668 //------------------------------dump_req--------------------------------------
1669 void Node::dump_req(outputStream *st) const {
1670   // Dump the required input edges
1671   for (uint i = 0; i < req(); i++) {    // For all required inputs
1672     Node* d = in(i);
1673     if (d == NULL) {
1674       st->print("_ ");
1675     } else if (NotANode(d)) {
1676       st->print("NotANode ");  // uninitialized, sentinel, garbage, etc.
1677     } else {
1678       st->print("%c%d ", Compile::current()->node_arena()->contains(d) ? ' ' : 'o', d->_idx);
1679     }
1680   }
1681 }
1682 
1683 
1684 //------------------------------dump_prec-------------------------------------
1685 void Node::dump_prec(outputStream *st) const {
1686   // Dump the precedence edges
1687   int any_prec = 0;
1688   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
1689     Node* p = in(i);
1690     if (p != NULL) {
1691       if (!any_prec++) st->print(" |");
1692       if (NotANode(p)) { st->print("NotANode "); continue; }
1693       st->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
1694     }
1695   }
1696 }
1697 
1698 //------------------------------dump_out--------------------------------------
1699 void Node::dump_out(outputStream *st) const {
1700   // Delimit the output edges
1701   st->print(" [[");
1702   // Dump the output edges
1703   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
1704     Node* u = _out[i];
1705     if (u == NULL) {
1706       st->print("_ ");
1707     } else if (NotANode(u)) {
1708       st->print("NotANode ");
1709     } else {
1710       st->print("%c%d ", Compile::current()->node_arena()->contains(u) ? ' ' : 'o', u->_idx);
1711     }
1712   }
1713   st->print("]] ");
1714 }
1715 
1716 //------------------------------dump_nodes-------------------------------------
1717 static void dump_nodes(const Node* start, int d, bool only_ctrl) {
1718   Node* s = (Node*)start; // remove const
1719   if (NotANode(s)) return;
1720 
1721   uint depth = (uint)ABS(d);
1722   int direction = d;
1723   Compile* C = Compile::current();
1724   GrowableArray <Node *> nstack(C->unique());
1725 
1726   nstack.append(s);
1727   int begin = 0;
1728   int end = 0;
1729   for(uint i = 0; i < depth; i++) {
1730     end = nstack.length();
1731     for(int j = begin; j < end; j++) {
1732       Node* tp  = nstack.at(j);
1733       uint limit = direction > 0 ? tp->len() : tp->outcnt();
1734       for(uint k = 0; k < limit; k++) {
1735         Node* n = direction > 0 ? tp->in(k) : tp->raw_out(k);
1736 
1737         if (NotANode(n))  continue;
1738         // do not recurse through top or the root (would reach unrelated stuff)
1739         if (n->is_Root() || n->is_top())  continue;
1740         if (only_ctrl && !n->is_CFG()) continue;
1741 
1742         bool on_stack = nstack.contains(n);
1743         if (!on_stack) {
1744           nstack.append(n);
1745         }
1746       }
1747     }
1748     begin = end;
1749   }
1750   end = nstack.length();
1751   if (direction > 0) {
1752     for(int j = end-1; j >= 0; j--) {
1753       nstack.at(j)->dump();
1754     }
1755   } else {
1756     for(int j = 0; j < end; j++) {
1757       nstack.at(j)->dump();
1758     }
1759   }
1760 }
1761 
1762 //------------------------------dump-------------------------------------------
1763 void Node::dump(int d) const {
1764   dump_nodes(this, d, false);
1765 }
1766 
1767 //------------------------------dump_ctrl--------------------------------------
1768 // Dump a Node's control history to depth
1769 void Node::dump_ctrl(int d) const {
1770   dump_nodes(this, d, true);
1771 }
1772 
1773 // VERIFICATION CODE
1774 // For each input edge to a node (ie - for each Use-Def edge), verify that
1775 // there is a corresponding Def-Use edge.
1776 //------------------------------verify_edges-----------------------------------
1777 void Node::verify_edges(Unique_Node_List &visited) {
1778   uint i, j, idx;
1779   int  cnt;
1780   Node *n;
1781 
1782   // Recursive termination test
1783   if (visited.member(this))  return;
1784   visited.push(this);
1785 
1786   // Walk over all input edges, checking for correspondence
1787   for( i = 0; i < len(); i++ ) {
1788     n = in(i);
1789     if (n != NULL && !n->is_top()) {
1790       // Count instances of (Node *)this
1791       cnt = 0;
1792       for (idx = 0; idx < n->_outcnt; idx++ ) {
1793         if (n->_out[idx] == (Node *)this)  cnt++;
1794       }
1795       assert( cnt > 0,"Failed to find Def-Use edge." );
1796       // Check for duplicate edges
1797       // walk the input array downcounting the input edges to n
1798       for( j = 0; j < len(); j++ ) {
1799         if( in(j) == n ) cnt--;
1800       }
1801       assert( cnt == 0,"Mismatched edge count.");
1802     } else if (n == NULL) {
1803       assert(i >= req() || i == 0 || is_Region() || is_Phi(), "only regions or phis have null data edges");
1804     } else {
1805       assert(n->is_top(), "sanity");
1806       // Nothing to check.
1807     }
1808   }
1809   // Recursive walk over all input edges
1810   for( i = 0; i < len(); i++ ) {
1811     n = in(i);
1812     if( n != NULL )
1813       in(i)->verify_edges(visited);
1814   }
1815 }
1816 
1817 //------------------------------verify_recur-----------------------------------
1818 static const Node *unique_top = NULL;
1819 
1820 void Node::verify_recur(const Node *n, int verify_depth,
1821                         VectorSet &old_space, VectorSet &new_space) {
1822   if ( verify_depth == 0 )  return;
1823   if (verify_depth > 0)  --verify_depth;
1824 
1825   Compile* C = Compile::current();
1826 
1827   // Contained in new_space or old_space?
1828   VectorSet *v = C->node_arena()->contains(n) ? &new_space : &old_space;
1829   // Check for visited in the proper space.  Numberings are not unique
1830   // across spaces so we need a separate VectorSet for each space.
1831   if( v->test_set(n->_idx) ) return;
1832 
1833   if (n->is_Con() && n->bottom_type() == Type::TOP) {
1834     if (C->cached_top_node() == NULL)
1835       C->set_cached_top_node((Node*)n);
1836     assert(C->cached_top_node() == n, "TOP node must be unique");
1837   }
1838 
1839   for( uint i = 0; i < n->len(); i++ ) {
1840     Node *x = n->in(i);
1841     if (!x || x->is_top()) continue;
1842 
1843     // Verify my input has a def-use edge to me
1844     if (true /*VerifyDefUse*/) {
1845       // Count use-def edges from n to x
1846       int cnt = 0;
1847       for( uint j = 0; j < n->len(); j++ )
1848         if( n->in(j) == x )
1849           cnt++;
1850       // Count def-use edges from x to n
1851       uint max = x->_outcnt;
1852       for( uint k = 0; k < max; k++ )
1853         if (x->_out[k] == n)
1854           cnt--;
1855       assert( cnt == 0, "mismatched def-use edge counts" );
1856     }
1857 
1858     verify_recur(x, verify_depth, old_space, new_space);
1859   }
1860 
1861 }
1862 
1863 //------------------------------verify-----------------------------------------
1864 // Check Def-Use info for my subgraph
1865 void Node::verify() const {
1866   Compile* C = Compile::current();
1867   Node* old_top = C->cached_top_node();
1868   ResourceMark rm;
1869   ResourceArea *area = Thread::current()->resource_area();
1870   VectorSet old_space(area), new_space(area);
1871   verify_recur(this, -1, old_space, new_space);
1872   C->set_cached_top_node(old_top);
1873 }
1874 #endif
1875 
1876 
1877 //------------------------------walk-------------------------------------------
1878 // Graph walk, with both pre-order and post-order functions
1879 void Node::walk(NFunc pre, NFunc post, void *env) {
1880   VectorSet visited(Thread::current()->resource_area()); // Setup for local walk
1881   walk_(pre, post, env, visited);
1882 }
1883 
1884 void Node::walk_(NFunc pre, NFunc post, void *env, VectorSet &visited) {
1885   if( visited.test_set(_idx) ) return;
1886   pre(*this,env);               // Call the pre-order walk function
1887   for( uint i=0; i<_max; i++ )
1888     if( in(i) )                 // Input exists and is not walked?
1889       in(i)->walk_(pre,post,env,visited); // Walk it with pre & post functions
1890   post(*this,env);              // Call the post-order walk function
1891 }
1892 
1893 void Node::nop(Node &, void*) {}
1894 
1895 //------------------------------Registers--------------------------------------
1896 // Do we Match on this edge index or not?  Generally false for Control
1897 // and true for everything else.  Weird for calls & returns.
1898 uint Node::match_edge(uint idx) const {
1899   return idx;                   // True for other than index 0 (control)
1900 }
1901 
1902 static RegMask _not_used_at_all;
1903 // Register classes are defined for specific machines
1904 const RegMask &Node::out_RegMask() const {
1905   ShouldNotCallThis();
1906   return _not_used_at_all;
1907 }
1908 
1909 const RegMask &Node::in_RegMask(uint) const {
1910   ShouldNotCallThis();
1911   return _not_used_at_all;
1912 }
1913 
1914 //=============================================================================
1915 //-----------------------------------------------------------------------------
1916 void Node_Array::reset( Arena *new_arena ) {
1917   _a->Afree(_nodes,_max*sizeof(Node*));
1918   _max   = 0;
1919   _nodes = NULL;
1920   _a     = new_arena;
1921 }
1922 
1923 //------------------------------clear------------------------------------------
1924 // Clear all entries in _nodes to NULL but keep storage
1925 void Node_Array::clear() {
1926   Copy::zero_to_bytes( _nodes, _max*sizeof(Node*) );
1927 }
1928 
1929 //-----------------------------------------------------------------------------
1930 void Node_Array::grow( uint i ) {
1931   if( !_max ) {
1932     _max = 1;
1933     _nodes = (Node**)_a->Amalloc( _max * sizeof(Node*) );
1934     _nodes[0] = NULL;
1935   }
1936   uint old = _max;
1937   while( i >= _max ) _max <<= 1;        // Double to fit
1938   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
1939   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
1940 }
1941 
1942 //-----------------------------------------------------------------------------
1943 void Node_Array::insert( uint i, Node *n ) {
1944   if( _nodes[_max-1] ) grow(_max);      // Get more space if full
1945   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i+1], ((_max-i-1)*sizeof(Node*)));
1946   _nodes[i] = n;
1947 }
1948 
1949 //-----------------------------------------------------------------------------
1950 void Node_Array::remove( uint i ) {
1951   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i+1], (HeapWord*)&_nodes[i], ((_max-i-1)*sizeof(Node*)));
1952   _nodes[_max-1] = NULL;
1953 }
1954 
1955 //-----------------------------------------------------------------------------
1956 void Node_Array::sort( C_sort_func_t func) {
1957   qsort( _nodes, _max, sizeof( Node* ), func );
1958 }
1959 
1960 //-----------------------------------------------------------------------------
1961 void Node_Array::dump() const {
1962 #ifndef PRODUCT
1963   for( uint i = 0; i < _max; i++ ) {
1964     Node *nn = _nodes[i];
1965     if( nn != NULL ) {
1966       tty->print("%5d--> ",i); nn->dump();
1967     }
1968   }
1969 #endif
1970 }
1971 
1972 //--------------------------is_iteratively_computed------------------------------
1973 // Operation appears to be iteratively computed (such as an induction variable)
1974 // It is possible for this operation to return false for a loop-varying
1975 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
1976 bool Node::is_iteratively_computed() {
1977   if (ideal_reg()) { // does operation have a result register?
1978     for (uint i = 1; i < req(); i++) {
1979       Node* n = in(i);
1980       if (n != NULL && n->is_Phi()) {
1981         for (uint j = 1; j < n->req(); j++) {
1982           if (n->in(j) == this) {
1983             return true;
1984           }
1985         }
1986       }
1987     }
1988   }
1989   return false;
1990 }
1991 
1992 //--------------------------find_similar------------------------------
1993 // Return a node with opcode "opc" and same inputs as "this" if one can
1994 // be found; Otherwise return NULL;
1995 Node* Node::find_similar(int opc) {
1996   if (req() >= 2) {
1997     Node* def = in(1);
1998     if (def && def->outcnt() >= 2) {
1999       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2000         Node* use = def->fast_out(i);
2001         if (use->Opcode() == opc &&
2002             use->req() == req()) {
2003           uint j;
2004           for (j = 0; j < use->req(); j++) {
2005             if (use->in(j) != in(j)) {
2006               break;
2007             }
2008           }
2009           if (j == use->req()) {
2010             return use;
2011           }
2012         }
2013       }
2014     }
2015   }
2016   return NULL;
2017 }
2018 
2019 
2020 //--------------------------unique_ctrl_out------------------------------
2021 // Return the unique control out if only one. Null if none or more than one.
2022 Node* Node::unique_ctrl_out() {
2023   Node* found = NULL;
2024   for (uint i = 0; i < outcnt(); i++) {
2025     Node* use = raw_out(i);
2026     if (use->is_CFG() && use != this) {
2027       if (found != NULL) return NULL;
2028       found = use;
2029     }
2030   }
2031   return found;
2032 }
2033 
2034 //=============================================================================
2035 //------------------------------yank-------------------------------------------
2036 // Find and remove
2037 void Node_List::yank( Node *n ) {
2038   uint i;
2039   for( i = 0; i < _cnt; i++ )
2040     if( _nodes[i] == n )
2041       break;
2042 
2043   if( i < _cnt )
2044     _nodes[i] = _nodes[--_cnt];
2045 }
2046 
2047 //------------------------------dump-------------------------------------------
2048 void Node_List::dump() const {
2049 #ifndef PRODUCT
2050   for( uint i = 0; i < _cnt; i++ )
2051     if( _nodes[i] ) {
2052       tty->print("%5d--> ",i);
2053       _nodes[i]->dump();
2054     }
2055 #endif
2056 }
2057 
2058 //=============================================================================
2059 //------------------------------remove-----------------------------------------
2060 void Unique_Node_List::remove( Node *n ) {
2061   if( _in_worklist[n->_idx] ) {
2062     for( uint i = 0; i < size(); i++ )
2063       if( _nodes[i] == n ) {
2064         map(i,Node_List::pop());
2065         _in_worklist >>= n->_idx;
2066         return;
2067       }
2068     ShouldNotReachHere();
2069   }
2070 }
2071 
2072 //-----------------------remove_useless_nodes----------------------------------
2073 // Remove useless nodes from worklist
2074 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2075 
2076   for( uint i = 0; i < size(); ++i ) {
2077     Node *n = at(i);
2078     assert( n != NULL, "Did not expect null entries in worklist");
2079     if( ! useful.test(n->_idx) ) {
2080       _in_worklist >>= n->_idx;
2081       map(i,Node_List::pop());
2082       // Node *replacement = Node_List::pop();
2083       // if( i != size() ) { // Check if removing last entry
2084       //   _nodes[i] = replacement;
2085       // }
2086       --i;  // Visit popped node
2087       // If it was last entry, loop terminates since size() was also reduced
2088     }
2089   }
2090 }
2091 
2092 //=============================================================================
2093 void Node_Stack::grow() {
2094   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2095   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2096   size_t max = old_max << 1;             // max * 2
2097   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2098   _inode_max = _inodes + max;
2099   _inode_top = _inodes + old_top;        // restore _top
2100 }
2101 
2102 // Node_Stack is used to map nodes.
2103 Node* Node_Stack::find(uint idx) const {
2104   uint sz = size();
2105   for (uint i=0; i < sz; i++) {
2106     if (idx == index_at(i) )
2107       return node_at(i);
2108   }
2109   return NULL;
2110 }
2111 
2112 //=============================================================================
2113 uint TypeNode::size_of() const { return sizeof(*this); }
2114 #ifndef PRODUCT
2115 void TypeNode::dump_spec(outputStream *st) const {
2116   if( !Verbose && !WizardMode ) {
2117     // standard dump does this in Verbose and WizardMode
2118     st->print(" #"); _type->dump_on(st);
2119   }
2120 }
2121 #endif
2122 uint TypeNode::hash() const {
2123   return Node::hash() + _type->hash();
2124 }
2125 uint TypeNode::cmp( const Node &n ) const
2126 { return !Type::cmp( _type, ((TypeNode&)n)._type ); }
2127 const Type *TypeNode::bottom_type() const { return _type; }
2128 const Type *TypeNode::Value( PhaseTransform * ) const { return _type; }
2129 
2130 //------------------------------ideal_reg--------------------------------------
2131 uint TypeNode::ideal_reg() const {
2132   return _type->ideal_reg();
2133 }