1 /*
   2  * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "libadt/vectset.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "opto/cfgnode.hpp"
  29 #include "opto/connode.hpp"
  30 #include "opto/loopnode.hpp"
  31 #include "opto/machnode.hpp"
  32 #include "opto/matcher.hpp"
  33 #include "opto/node.hpp"
  34 #include "opto/opcodes.hpp"
  35 #include "opto/regmask.hpp"
  36 #include "opto/type.hpp"
  37 #include "utilities/copy.hpp"
  38 
  39 class RegMask;
  40 // #include "phase.hpp"
  41 class PhaseTransform;
  42 class PhaseGVN;
  43 
  44 // Arena we are currently building Nodes in
  45 const uint Node::NotAMachineReg = 0xffff0000;
  46 
  47 #ifndef PRODUCT
  48 extern int nodes_created;
  49 #endif
  50 
  51 #ifdef ASSERT
  52 
  53 //-------------------------- construct_node------------------------------------
  54 // Set a breakpoint here to identify where a particular node index is built.
  55 void Node::verify_construction() {
  56   _debug_orig = NULL;
  57   int old_debug_idx = Compile::debug_idx();
  58   int new_debug_idx = old_debug_idx+1;
  59   if (new_debug_idx > 0) {
  60     // Arrange that the lowest five decimal digits of _debug_idx
  61     // will repeat those of _idx. In case this is somehow pathological,
  62     // we continue to assign negative numbers (!) consecutively.
  63     const int mod = 100000;
  64     int bump = (int)(_idx - new_debug_idx) % mod;
  65     if (bump < 0)  bump += mod;
  66     assert(bump >= 0 && bump < mod, "");
  67     new_debug_idx += bump;
  68   }
  69   Compile::set_debug_idx(new_debug_idx);
  70   set_debug_idx( new_debug_idx );
  71   assert(Compile::current()->unique() < (INT_MAX - 1), "Node limit exceeded INT_MAX");
  72   assert(Compile::current()->live_nodes() < (uint)MaxNodeLimit, "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 
 290 // Out-of-line code from node constructors.
 291 // Executed only when extra debug info. is being passed around.
 292 static void init_node_notes(Compile* C, int idx, Node_Notes* nn) {
 293   C->set_node_notes_at(idx, nn);
 294 }
 295 
 296 // Shared initialization code.
 297 inline int Node::Init(int req, Compile* C) {
 298   assert(Compile::current() == C, "must use operator new(Compile*)");
 299   int idx = C->next_unique();
 300 
 301   // Allocate memory for the necessary number of edges.
 302   if (req > 0) {
 303     // Allocate space for _in array to have double alignment.
 304     _in = (Node **) ((char *) (C->node_arena()->Amalloc_D(req * sizeof(void*))));
 305 #ifdef ASSERT
 306     _in[req-1] = this; // magic cookie for assertion check
 307 #endif
 308   }
 309   // If there are default notes floating around, capture them:
 310   Node_Notes* nn = C->default_node_notes();
 311   if (nn != NULL)  init_node_notes(C, idx, nn);
 312 
 313   // Note:  At this point, C is dead,
 314   // and we begin to initialize the new Node.
 315 
 316   _cnt = _max = req;
 317   _outcnt = _outmax = 0;
 318   _class_id = Class_Node;
 319   _flags = 0;
 320   _out = NO_OUT_ARRAY;
 321   return idx;
 322 }
 323 
 324 //------------------------------Node-------------------------------------------
 325 // Create a Node, with a given number of required edges.
 326 Node::Node(uint req)
 327   : _idx(IDX_INIT(req))
 328 {
 329   assert( req < (uint)(MaxNodeLimit - NodeLimitFudgeFactor), "Input limit exceeded" );
 330   debug_only( verify_construction() );
 331   NOT_PRODUCT(nodes_created++);
 332   if (req == 0) {
 333     assert( _in == (Node**)this, "Must not pass arg count to 'new'" );
 334     _in = NULL;
 335   } else {
 336     assert( _in[req-1] == this, "Must pass arg count to 'new'" );
 337     Node** to = _in;
 338     for(uint i = 0; i < req; i++) {
 339       to[i] = NULL;
 340     }
 341   }
 342 }
 343 
 344 //------------------------------Node-------------------------------------------
 345 Node::Node(Node *n0)
 346   : _idx(IDX_INIT(1))
 347 {
 348   debug_only( verify_construction() );
 349   NOT_PRODUCT(nodes_created++);
 350   // Assert we allocated space for input array already
 351   assert( _in[0] == this, "Must pass arg count to 'new'" );
 352   assert( is_not_dead(n0), "can not use dead node");
 353   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 354 }
 355 
 356 //------------------------------Node-------------------------------------------
 357 Node::Node(Node *n0, Node *n1)
 358   : _idx(IDX_INIT(2))
 359 {
 360   debug_only( verify_construction() );
 361   NOT_PRODUCT(nodes_created++);
 362   // Assert we allocated space for input array already
 363   assert( _in[1] == this, "Must pass arg count to 'new'" );
 364   assert( is_not_dead(n0), "can not use dead node");
 365   assert( is_not_dead(n1), "can not use dead node");
 366   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 367   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 368 }
 369 
 370 //------------------------------Node-------------------------------------------
 371 Node::Node(Node *n0, Node *n1, Node *n2)
 372   : _idx(IDX_INIT(3))
 373 {
 374   debug_only( verify_construction() );
 375   NOT_PRODUCT(nodes_created++);
 376   // Assert we allocated space for input array already
 377   assert( _in[2] == this, "Must pass arg count to 'new'" );
 378   assert( is_not_dead(n0), "can not use dead node");
 379   assert( is_not_dead(n1), "can not use dead node");
 380   assert( is_not_dead(n2), "can not use dead node");
 381   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 382   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 383   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 384 }
 385 
 386 //------------------------------Node-------------------------------------------
 387 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3)
 388   : _idx(IDX_INIT(4))
 389 {
 390   debug_only( verify_construction() );
 391   NOT_PRODUCT(nodes_created++);
 392   // Assert we allocated space for input array already
 393   assert( _in[3] == 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   assert( is_not_dead(n3), "can not use dead node");
 398   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 399   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 400   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 401   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 402 }
 403 
 404 //------------------------------Node-------------------------------------------
 405 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3, Node *n4)
 406   : _idx(IDX_INIT(5))
 407 {
 408   debug_only( verify_construction() );
 409   NOT_PRODUCT(nodes_created++);
 410   // Assert we allocated space for input array already
 411   assert( _in[4] == this, "Must pass arg count to 'new'" );
 412   assert( is_not_dead(n0), "can not use dead node");
 413   assert( is_not_dead(n1), "can not use dead node");
 414   assert( is_not_dead(n2), "can not use dead node");
 415   assert( is_not_dead(n3), "can not use dead node");
 416   assert( is_not_dead(n4), "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   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 422 }
 423 
 424 //------------------------------Node-------------------------------------------
 425 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 426                      Node *n4, Node *n5)
 427   : _idx(IDX_INIT(6))
 428 {
 429   debug_only( verify_construction() );
 430   NOT_PRODUCT(nodes_created++);
 431   // Assert we allocated space for input array already
 432   assert( _in[5] == this, "Must pass arg count to 'new'" );
 433   assert( is_not_dead(n0), "can not use dead node");
 434   assert( is_not_dead(n1), "can not use dead node");
 435   assert( is_not_dead(n2), "can not use dead node");
 436   assert( is_not_dead(n3), "can not use dead node");
 437   assert( is_not_dead(n4), "can not use dead node");
 438   assert( is_not_dead(n5), "can not use dead node");
 439   _in[0] = n0; if (n0 != 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   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 445 }
 446 
 447 //------------------------------Node-------------------------------------------
 448 Node::Node(Node *n0, Node *n1, Node *n2, Node *n3,
 449                      Node *n4, Node *n5, Node *n6)
 450   : _idx(IDX_INIT(7))
 451 {
 452   debug_only( verify_construction() );
 453   NOT_PRODUCT(nodes_created++);
 454   // Assert we allocated space for input array already
 455   assert( _in[6] == this, "Must pass arg count to 'new'" );
 456   assert( is_not_dead(n0), "can not use dead node");
 457   assert( is_not_dead(n1), "can not use dead node");
 458   assert( is_not_dead(n2), "can not use dead node");
 459   assert( is_not_dead(n3), "can not use dead node");
 460   assert( is_not_dead(n4), "can not use dead node");
 461   assert( is_not_dead(n5), "can not use dead node");
 462   assert( is_not_dead(n6), "can not use dead node");
 463   _in[0] = n0; if (n0 != NULL) n0->add_out((Node *)this);
 464   _in[1] = n1; if (n1 != NULL) n1->add_out((Node *)this);
 465   _in[2] = n2; if (n2 != NULL) n2->add_out((Node *)this);
 466   _in[3] = n3; if (n3 != NULL) n3->add_out((Node *)this);
 467   _in[4] = n4; if (n4 != NULL) n4->add_out((Node *)this);
 468   _in[5] = n5; if (n5 != NULL) n5->add_out((Node *)this);
 469   _in[6] = n6; if (n6 != NULL) n6->add_out((Node *)this);
 470 }
 471 
 472 
 473 //------------------------------clone------------------------------------------
 474 // Clone a Node.
 475 Node *Node::clone() const {
 476   Compile* C = Compile::current();
 477   uint s = size_of();           // Size of inherited Node
 478   Node *n = (Node*)C->node_arena()->Amalloc_D(size_of() + _max*sizeof(Node*));
 479   Copy::conjoint_words_to_lower((HeapWord*)this, (HeapWord*)n, s);
 480   // Set the new input pointer array
 481   n->_in = (Node**)(((char*)n)+s);
 482   // Cannot share the old output pointer array, so kill it
 483   n->_out = NO_OUT_ARRAY;
 484   // And reset the counters to 0
 485   n->_outcnt = 0;
 486   n->_outmax = 0;
 487   // Unlock this guy, since he is not in any hash table.
 488   debug_only(n->_hash_lock = 0);
 489   // Walk the old node's input list to duplicate its edges
 490   uint i;
 491   for( i = 0; i < len(); i++ ) {
 492     Node *x = in(i);
 493     n->_in[i] = x;
 494     if (x != NULL) x->add_out(n);
 495   }
 496   if (is_macro())
 497     C->add_macro_node(n);
 498   if (is_expensive())
 499     C->add_expensive_node(n);
 500 
 501   n->set_idx(C->next_unique()); // Get new unique index as well
 502   debug_only( n->verify_construction() );
 503   NOT_PRODUCT(nodes_created++);
 504   // Do not patch over the debug_idx of a clone, because it makes it
 505   // impossible to break on the clone's moment of creation.
 506   //debug_only( n->set_debug_idx( debug_idx() ) );
 507 
 508   C->copy_node_notes_to(n, (Node*) this);
 509 
 510   // MachNode clone
 511   uint nopnds;
 512   if (this->is_Mach() && (nopnds = this->as_Mach()->num_opnds()) > 0) {
 513     MachNode *mach  = n->as_Mach();
 514     MachNode *mthis = this->as_Mach();
 515     // Get address of _opnd_array.
 516     // It should be the same offset since it is the clone of this node.
 517     MachOper **from = mthis->_opnds;
 518     MachOper **to = (MachOper **)((size_t)(&mach->_opnds) +
 519                     pointer_delta((const void*)from,
 520                                   (const void*)(&mthis->_opnds), 1));
 521     mach->_opnds = to;
 522     for ( uint i = 0; i < nopnds; ++i ) {
 523       to[i] = from[i]->clone(C);
 524     }
 525   }
 526   // cloning CallNode may need to clone JVMState
 527   if (n->is_Call()) {
 528     n->as_Call()->clone_jvms(C);
 529   }
 530   if (n->is_SafePoint()) {
 531     n->as_SafePoint()->clone_replaced_nodes();
 532   }
 533   return n;                     // Return the clone
 534 }
 535 
 536 //---------------------------setup_is_top--------------------------------------
 537 // Call this when changing the top node, to reassert the invariants
 538 // required by Node::is_top.  See Compile::set_cached_top_node.
 539 void Node::setup_is_top() {
 540   if (this == (Node*)Compile::current()->top()) {
 541     // This node has just become top.  Kill its out array.
 542     _outcnt = _outmax = 0;
 543     _out = NULL;                           // marker value for top
 544     assert(is_top(), "must be top");
 545   } else {
 546     if (_out == NULL)  _out = NO_OUT_ARRAY;
 547     assert(!is_top(), "must not be top");
 548   }
 549 }
 550 
 551 
 552 //------------------------------~Node------------------------------------------
 553 // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 554 extern int reclaim_idx ;
 555 extern int reclaim_in  ;
 556 extern int reclaim_node;
 557 void Node::destruct() {
 558   // Eagerly reclaim unique Node numberings
 559   Compile* compile = Compile::current();
 560   if ((uint)_idx+1 == compile->unique()) {
 561     compile->set_unique(compile->unique()-1);
 562 #ifdef ASSERT
 563     reclaim_idx++;
 564 #endif
 565   }
 566   // Clear debug info:
 567   Node_Notes* nn = compile->node_notes_at(_idx);
 568   if (nn != NULL)  nn->clear();
 569   // Walk the input array, freeing the corresponding output edges
 570   _cnt = _max;  // forget req/prec distinction
 571   uint i;
 572   for( i = 0; i < _max; i++ ) {
 573     set_req(i, NULL);
 574     //assert(def->out(def->outcnt()-1) == (Node *)this,"bad def-use hacking in reclaim");
 575   }
 576   assert(outcnt() == 0, "deleting a node must not leave a dangling use");
 577   // See if the input array was allocated just prior to the object
 578   int edge_size = _max*sizeof(void*);
 579   int out_edge_size = _outmax*sizeof(void*);
 580   char *edge_end = ((char*)_in) + edge_size;
 581   char *out_array = (char*)(_out == NO_OUT_ARRAY? NULL: _out);
 582   char *out_edge_end = out_array + out_edge_size;
 583   int node_size = size_of();
 584 
 585   // Free the output edge array
 586   if (out_edge_size > 0) {
 587 #ifdef ASSERT
 588     if( out_edge_end == compile->node_arena()->hwm() )
 589       reclaim_in  += out_edge_size;  // count reclaimed out edges with in edges
 590 #endif
 591     compile->node_arena()->Afree(out_array, out_edge_size);
 592   }
 593 
 594   // Free the input edge array and the node itself
 595   if( edge_end == (char*)this ) {
 596 #ifdef ASSERT
 597     if( edge_end+node_size == compile->node_arena()->hwm() ) {
 598       reclaim_in  += edge_size;
 599       reclaim_node+= node_size;
 600     }
 601 #else
 602     // It was; free the input array and object all in one hit
 603     compile->node_arena()->Afree(_in,edge_size+node_size);
 604 #endif
 605   } else {
 606 
 607     // Free just the input array
 608 #ifdef ASSERT
 609     if( edge_end == compile->node_arena()->hwm() )
 610       reclaim_in  += edge_size;
 611 #endif
 612     compile->node_arena()->Afree(_in,edge_size);
 613 
 614     // Free just the object
 615 #ifdef ASSERT
 616     if( ((char*)this) + node_size == compile->node_arena()->hwm() )
 617       reclaim_node+= node_size;
 618 #else
 619     compile->node_arena()->Afree(this,node_size);
 620 #endif
 621   }
 622   if (is_macro()) {
 623     compile->remove_macro_node(this);
 624   }
 625   if (is_expensive()) {
 626     compile->remove_expensive_node(this);
 627   }
 628   if (is_SafePoint()) {
 629     as_SafePoint()->delete_replaced_nodes();
 630   }
 631 #ifdef ASSERT
 632   // We will not actually delete the storage, but we'll make the node unusable.
 633   *(address*)this = badAddress;  // smash the C++ vtbl, probably
 634   _in = _out = (Node**) badAddress;
 635   _max = _cnt = _outmax = _outcnt = 0;
 636 #endif
 637 }
 638 
 639 //------------------------------grow-------------------------------------------
 640 // Grow the input array, making space for more edges
 641 void Node::grow( uint len ) {
 642   Arena* arena = Compile::current()->node_arena();
 643   uint new_max = _max;
 644   if( new_max == 0 ) {
 645     _max = 4;
 646     _in = (Node**)arena->Amalloc(4*sizeof(Node*));
 647     Node** to = _in;
 648     to[0] = NULL;
 649     to[1] = NULL;
 650     to[2] = NULL;
 651     to[3] = NULL;
 652     return;
 653   }
 654   while( new_max <= len ) new_max <<= 1; // Find next power-of-2
 655   // Trimming to limit allows a uint8 to handle up to 255 edges.
 656   // Previously I was using only powers-of-2 which peaked at 128 edges.
 657   //if( new_max >= limit ) new_max = limit-1;
 658   _in = (Node**)arena->Arealloc(_in, _max*sizeof(Node*), new_max*sizeof(Node*));
 659   Copy::zero_to_bytes(&_in[_max], (new_max-_max)*sizeof(Node*)); // NULL all new space
 660   _max = new_max;               // Record new max length
 661   // This assertion makes sure that Node::_max is wide enough to
 662   // represent the numerical value of new_max.
 663   assert(_max == new_max && _max > len, "int width of _max is too small");
 664 }
 665 
 666 //-----------------------------out_grow----------------------------------------
 667 // Grow the input array, making space for more edges
 668 void Node::out_grow( uint len ) {
 669   assert(!is_top(), "cannot grow a top node's out array");
 670   Arena* arena = Compile::current()->node_arena();
 671   uint new_max = _outmax;
 672   if( new_max == 0 ) {
 673     _outmax = 4;
 674     _out = (Node **)arena->Amalloc(4*sizeof(Node*));
 675     return;
 676   }
 677   while( new_max <= len ) new_max <<= 1; // Find next power-of-2
 678   // Trimming to limit allows a uint8 to handle up to 255 edges.
 679   // Previously I was using only powers-of-2 which peaked at 128 edges.
 680   //if( new_max >= limit ) new_max = limit-1;
 681   assert(_out != NULL && _out != NO_OUT_ARRAY, "out must have sensible value");
 682   _out = (Node**)arena->Arealloc(_out,_outmax*sizeof(Node*),new_max*sizeof(Node*));
 683   //Copy::zero_to_bytes(&_out[_outmax], (new_max-_outmax)*sizeof(Node*)); // NULL all new space
 684   _outmax = new_max;               // Record new max length
 685   // This assertion makes sure that Node::_max is wide enough to
 686   // represent the numerical value of new_max.
 687   assert(_outmax == new_max && _outmax > len, "int width of _outmax is too small");
 688 }
 689 
 690 #ifdef ASSERT
 691 //------------------------------is_dead----------------------------------------
 692 bool Node::is_dead() const {
 693   // Mach and pinch point nodes may look like dead.
 694   if( is_top() || is_Mach() || (Opcode() == Op_Node && _outcnt > 0) )
 695     return false;
 696   for( uint i = 0; i < _max; i++ )
 697     if( _in[i] != NULL )
 698       return false;
 699   dump();
 700   return true;
 701 }
 702 #endif
 703 
 704 
 705 //------------------------------is_unreachable---------------------------------
 706 bool Node::is_unreachable(PhaseIterGVN &igvn) const {
 707   assert(!is_Mach(), "doesn't work with MachNodes");
 708   return outcnt() == 0 || igvn.type(this) == Type::TOP || in(0)->is_top();
 709 }
 710 
 711 //------------------------------add_req----------------------------------------
 712 // Add a new required input at the end
 713 void Node::add_req( Node *n ) {
 714   assert( is_not_dead(n), "can not use dead node");
 715 
 716   // Look to see if I can move precedence down one without reallocating
 717   if( (_cnt >= _max) || (in(_max-1) != NULL) )
 718     grow( _max+1 );
 719 
 720   // Find a precedence edge to move
 721   if( in(_cnt) != NULL ) {       // Next precedence edge is busy?
 722     uint i;
 723     for( i=_cnt; i<_max; i++ )
 724       if( in(i) == NULL )       // Find the NULL at end of prec edge list
 725         break;                  // There must be one, since we grew the array
 726     _in[i] = in(_cnt);          // Move prec over, making space for req edge
 727   }
 728   _in[_cnt++] = n;            // Stuff over old prec edge
 729   if (n != NULL) n->add_out((Node *)this);
 730 }
 731 
 732 //---------------------------add_req_batch-------------------------------------
 733 // Add a new required input at the end
 734 void Node::add_req_batch( Node *n, uint m ) {
 735   assert( is_not_dead(n), "can not use dead node");
 736   // check various edge cases
 737   if ((int)m <= 1) {
 738     assert((int)m >= 0, "oob");
 739     if (m != 0)  add_req(n);
 740     return;
 741   }
 742 
 743   // Look to see if I can move precedence down one without reallocating
 744   if( (_cnt+m) > _max || _in[_max-m] )
 745     grow( _max+m );
 746 
 747   // Find a precedence edge to move
 748   if( _in[_cnt] != NULL ) {     // Next precedence edge is busy?
 749     uint i;
 750     for( i=_cnt; i<_max; i++ )
 751       if( _in[i] == NULL )      // Find the NULL at end of prec edge list
 752         break;                  // There must be one, since we grew the array
 753     // Slide all the precs over by m positions (assume #prec << m).
 754     Copy::conjoint_words_to_higher((HeapWord*)&_in[_cnt], (HeapWord*)&_in[_cnt+m], ((i-_cnt)*sizeof(Node*)));
 755   }
 756 
 757   // Stuff over the old prec edges
 758   for(uint i=0; i<m; i++ ) {
 759     _in[_cnt++] = n;
 760   }
 761 
 762   // Insert multiple out edges on the node.
 763   if (n != NULL && !n->is_top()) {
 764     for(uint i=0; i<m; i++ ) {
 765       n->add_out((Node *)this);
 766     }
 767   }
 768 }
 769 
 770 //------------------------------del_req----------------------------------------
 771 // Delete the required edge and compact the edge array
 772 void Node::del_req( uint idx ) {
 773   assert( idx < _cnt, "oob");
 774   assert( !VerifyHashTableKeys || _hash_lock == 0,
 775           "remove node from hash table before modifying it");
 776   // First remove corresponding def-use edge
 777   Node *n = in(idx);
 778   if (n != NULL) n->del_out((Node *)this);
 779   _in[idx] = in(--_cnt);  // Compact the array
 780   _in[_cnt] = NULL;       // NULL out emptied slot
 781 }
 782 
 783 //------------------------------del_req_ordered--------------------------------
 784 // Delete the required edge and compact the edge array with preserved order
 785 void Node::del_req_ordered( uint idx ) {
 786   assert( idx < _cnt, "oob");
 787   assert( !VerifyHashTableKeys || _hash_lock == 0,
 788           "remove node from hash table before modifying it");
 789   // First remove corresponding def-use edge
 790   Node *n = in(idx);
 791   if (n != NULL) n->del_out((Node *)this);
 792   if (idx < _cnt - 1) { // Not last edge ?
 793     Copy::conjoint_words_to_lower((HeapWord*)&_in[idx+1], (HeapWord*)&_in[idx], ((_cnt-idx-1)*sizeof(Node*)));
 794   }
 795   _in[--_cnt] = NULL;   // NULL out emptied slot
 796 }
 797 
 798 //------------------------------ins_req----------------------------------------
 799 // Insert a new required input at the end
 800 void Node::ins_req( uint idx, Node *n ) {
 801   assert( is_not_dead(n), "can not use dead node");
 802   add_req(NULL);                // Make space
 803   assert( idx < _max, "Must have allocated enough space");
 804   // Slide over
 805   if(_cnt-idx-1 > 0) {
 806     Copy::conjoint_words_to_higher((HeapWord*)&_in[idx], (HeapWord*)&_in[idx+1], ((_cnt-idx-1)*sizeof(Node*)));
 807   }
 808   _in[idx] = n;                            // Stuff over old required edge
 809   if (n != NULL) n->add_out((Node *)this); // Add reciprocal def-use edge
 810 }
 811 
 812 //-----------------------------find_edge---------------------------------------
 813 int Node::find_edge(Node* n) {
 814   for (uint i = 0; i < len(); i++) {
 815     if (_in[i] == n)  return i;
 816   }
 817   return -1;
 818 }
 819 
 820 //----------------------------replace_edge-------------------------------------
 821 int Node::replace_edge(Node* old, Node* neww) {
 822   if (old == neww)  return 0;  // nothing to do
 823   uint nrep = 0;
 824   for (uint i = 0; i < len(); i++) {
 825     if (in(i) == old) {
 826       if (i < req())
 827         set_req(i, neww);
 828       else
 829         set_prec(i, neww);
 830       nrep++;
 831     }
 832   }
 833   return nrep;
 834 }
 835 
 836 /**
 837  * Replace input edges in the range pointing to 'old' node.
 838  */
 839 int Node::replace_edges_in_range(Node* old, Node* neww, int start, int end) {
 840   if (old == neww)  return 0;  // nothing to do
 841   uint nrep = 0;
 842   for (int i = start; i < end; i++) {
 843     if (in(i) == old) {
 844       set_req(i, neww);
 845       nrep++;
 846     }
 847   }
 848   return nrep;
 849 }
 850 
 851 //-------------------------disconnect_inputs-----------------------------------
 852 // NULL out all inputs to eliminate incoming Def-Use edges.
 853 // Return the number of edges between 'n' and 'this'
 854 int Node::disconnect_inputs(Node *n, Compile* C) {
 855   int edges_to_n = 0;
 856 
 857   uint cnt = req();
 858   for( uint i = 0; i < cnt; ++i ) {
 859     if( in(i) == 0 ) continue;
 860     if( in(i) == n ) ++edges_to_n;
 861     set_req(i, NULL);
 862   }
 863   // Remove precedence edges if any exist
 864   // Note: Safepoints may have precedence edges, even during parsing
 865   if( (req() != len()) && (in(req()) != NULL) ) {
 866     uint max = len();
 867     for( uint i = 0; i < max; ++i ) {
 868       if( in(i) == 0 ) continue;
 869       if( in(i) == n ) ++edges_to_n;
 870       set_prec(i, NULL);
 871     }
 872   }
 873 
 874   // Node::destruct requires all out edges be deleted first
 875   // debug_only(destruct();)   // no reuse benefit expected
 876   if (edges_to_n == 0) {
 877     C->record_dead_node(_idx);
 878   }
 879   return edges_to_n;
 880 }
 881 
 882 //-----------------------------uncast---------------------------------------
 883 // %%% Temporary, until we sort out CheckCastPP vs. CastPP.
 884 // Strip away casting.  (It is depth-limited.)
 885 Node* Node::uncast() const {
 886   // Should be inline:
 887   //return is_ConstraintCast() ? uncast_helper(this) : (Node*) this;
 888   if (is_ConstraintCast() || is_CheckCastPP())
 889     return uncast_helper(this);
 890   else
 891     return (Node*) this;
 892 }
 893 
 894 //---------------------------uncast_helper-------------------------------------
 895 Node* Node::uncast_helper(const Node* p) {
 896 #ifdef ASSERT
 897   uint depth_count = 0;
 898   const Node* orig_p = p;
 899 #endif
 900 
 901   while (true) {
 902 #ifdef ASSERT
 903     if (depth_count >= K) {
 904       orig_p->dump(4);
 905       if (p != orig_p)
 906         p->dump(1);
 907     }
 908     assert(depth_count++ < K, "infinite loop in Node::uncast_helper");
 909 #endif
 910     if (p == NULL || p->req() != 2) {
 911       break;
 912     } else if (p->is_ConstraintCast()) {
 913       p = p->in(1);
 914     } else if (p->is_CheckCastPP()) {
 915       p = p->in(1);
 916     } else {
 917       break;
 918     }
 919   }
 920   return (Node*) p;
 921 }
 922 
 923 //------------------------------add_prec---------------------------------------
 924 // Add a new precedence input.  Precedence inputs are unordered, with
 925 // duplicates removed and NULLs packed down at the end.
 926 void Node::add_prec( Node *n ) {
 927   assert( is_not_dead(n), "can not use dead node");
 928 
 929   // Check for NULL at end
 930   if( _cnt >= _max || in(_max-1) )
 931     grow( _max+1 );
 932 
 933   // Find a precedence edge to move
 934   uint i = _cnt;
 935   while( in(i) != NULL ) i++;
 936   _in[i] = n;                                // Stuff prec edge over NULL
 937   if ( n != NULL) n->add_out((Node *)this);  // Add mirror edge
 938 }
 939 
 940 //------------------------------rm_prec----------------------------------------
 941 // Remove a precedence input.  Precedence inputs are unordered, with
 942 // duplicates removed and NULLs packed down at the end.
 943 void Node::rm_prec( uint j ) {
 944 
 945   // Find end of precedence list to pack NULLs
 946   uint i;
 947   for( i=j; i<_max; i++ )
 948     if( !_in[i] )               // Find the NULL at end of prec edge list
 949       break;
 950   if (_in[j] != NULL) _in[j]->del_out((Node *)this);
 951   _in[j] = _in[--i];            // Move last element over removed guy
 952   _in[i] = NULL;                // NULL out last element
 953 }
 954 
 955 //------------------------------size_of----------------------------------------
 956 uint Node::size_of() const { return sizeof(*this); }
 957 
 958 //------------------------------ideal_reg--------------------------------------
 959 uint Node::ideal_reg() const { return 0; }
 960 
 961 //------------------------------jvms-------------------------------------------
 962 JVMState* Node::jvms() const { return NULL; }
 963 
 964 #ifdef ASSERT
 965 //------------------------------jvms-------------------------------------------
 966 bool Node::verify_jvms(const JVMState* using_jvms) const {
 967   for (JVMState* jvms = this->jvms(); jvms != NULL; jvms = jvms->caller()) {
 968     if (jvms == using_jvms)  return true;
 969   }
 970   return false;
 971 }
 972 
 973 //------------------------------init_NodeProperty------------------------------
 974 void Node::init_NodeProperty() {
 975   assert(_max_classes <= max_jushort, "too many NodeProperty classes");
 976   assert(_max_flags <= max_jushort, "too many NodeProperty flags");
 977 }
 978 #endif
 979 
 980 //------------------------------format-----------------------------------------
 981 // Print as assembly
 982 void Node::format( PhaseRegAlloc *, outputStream *st ) const {}
 983 //------------------------------emit-------------------------------------------
 984 // Emit bytes starting at parameter 'ptr'.
 985 void Node::emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const {}
 986 //------------------------------size-------------------------------------------
 987 // Size of instruction in bytes
 988 uint Node::size(PhaseRegAlloc *ra_) const { return 0; }
 989 
 990 //------------------------------CFG Construction-------------------------------
 991 // Nodes that end basic blocks, e.g. IfTrue/IfFalse, JumpProjNode, Root,
 992 // Goto and Return.
 993 const Node *Node::is_block_proj() const { return 0; }
 994 
 995 // Minimum guaranteed type
 996 const Type *Node::bottom_type() const { return Type::BOTTOM; }
 997 
 998 
 999 //------------------------------raise_bottom_type------------------------------
1000 // Get the worst-case Type output for this Node.
1001 void Node::raise_bottom_type(const Type* new_type) {
1002   if (is_Type()) {
1003     TypeNode *n = this->as_Type();
1004     if (VerifyAliases) {
1005       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1006     }
1007     n->set_type(new_type);
1008   } else if (is_Load()) {
1009     LoadNode *n = this->as_Load();
1010     if (VerifyAliases) {
1011       assert(new_type->higher_equal_speculative(n->type()), "new type must refine old type");
1012     }
1013     n->set_type(new_type);
1014   }
1015 }
1016 
1017 //------------------------------Identity---------------------------------------
1018 // Return a node that the given node is equivalent to.
1019 Node *Node::Identity( PhaseTransform * ) {
1020   return this;                  // Default to no identities
1021 }
1022 
1023 //------------------------------Value------------------------------------------
1024 // Compute a new Type for a node using the Type of the inputs.
1025 const Type *Node::Value( PhaseTransform * ) const {
1026   return bottom_type();         // Default to worst-case Type
1027 }
1028 
1029 //------------------------------Ideal------------------------------------------
1030 //
1031 // 'Idealize' the graph rooted at this Node.
1032 //
1033 // In order to be efficient and flexible there are some subtle invariants
1034 // these Ideal calls need to hold.  Running with '+VerifyIterativeGVN' checks
1035 // these invariants, although its too slow to have on by default.  If you are
1036 // hacking an Ideal call, be sure to test with +VerifyIterativeGVN!
1037 //
1038 // The Ideal call almost arbitrarily reshape the graph rooted at the 'this'
1039 // pointer.  If ANY change is made, it must return the root of the reshaped
1040 // graph - even if the root is the same Node.  Example: swapping the inputs
1041 // to an AddINode gives the same answer and same root, but you still have to
1042 // return the 'this' pointer instead of NULL.
1043 //
1044 // You cannot return an OLD Node, except for the 'this' pointer.  Use the
1045 // Identity call to return an old Node; basically if Identity can find
1046 // another Node have the Ideal call make no change and return NULL.
1047 // Example: AddINode::Ideal must check for add of zero; in this case it
1048 // returns NULL instead of doing any graph reshaping.
1049 //
1050 // You cannot modify any old Nodes except for the 'this' pointer.  Due to
1051 // sharing there may be other users of the old Nodes relying on their current
1052 // semantics.  Modifying them will break the other users.
1053 // Example: when reshape "(X+3)+4" into "X+7" you must leave the Node for
1054 // "X+3" unchanged in case it is shared.
1055 //
1056 // If you modify the 'this' pointer's inputs, you should use
1057 // 'set_req'.  If you are making a new Node (either as the new root or
1058 // some new internal piece) you may use 'init_req' to set the initial
1059 // value.  You can make a new Node with either 'new' or 'clone'.  In
1060 // either case, def-use info is correctly maintained.
1061 //
1062 // Example: reshape "(X+3)+4" into "X+7":
1063 //    set_req(1, in(1)->in(1));
1064 //    set_req(2, phase->intcon(7));
1065 //    return this;
1066 // Example: reshape "X*4" into "X<<2"
1067 //    return new (C) LShiftINode(in(1), phase->intcon(2));
1068 //
1069 // You must call 'phase->transform(X)' on any new Nodes X you make, except
1070 // for the returned root node.  Example: reshape "X*31" with "(X<<5)-X".
1071 //    Node *shift=phase->transform(new(C)LShiftINode(in(1),phase->intcon(5)));
1072 //    return new (C) AddINode(shift, in(1));
1073 //
1074 // When making a Node for a constant use 'phase->makecon' or 'phase->intcon'.
1075 // These forms are faster than 'phase->transform(new (C) ConNode())' and Do
1076 // The Right Thing with def-use info.
1077 //
1078 // You cannot bury the 'this' Node inside of a graph reshape.  If the reshaped
1079 // graph uses the 'this' Node it must be the root.  If you want a Node with
1080 // the same Opcode as the 'this' pointer use 'clone'.
1081 //
1082 Node *Node::Ideal(PhaseGVN *phase, bool can_reshape) {
1083   return NULL;                  // Default to being Ideal already
1084 }
1085 
1086 // Some nodes have specific Ideal subgraph transformations only if they are
1087 // unique users of specific nodes. Such nodes should be put on IGVN worklist
1088 // for the transformations to happen.
1089 bool Node::has_special_unique_user() const {
1090   assert(outcnt() == 1, "match only for unique out");
1091   Node* n = unique_out();
1092   int op  = Opcode();
1093   if( this->is_Store() ) {
1094     // Condition for back-to-back stores folding.
1095     return n->Opcode() == op && n->in(MemNode::Memory) == this;
1096   } else if (this->is_Load()) {
1097     // Condition for removing an unused LoadNode from the MemBarAcquire precedence input
1098     return n->Opcode() == Op_MemBarAcquire;
1099   } else if( op == Op_AddL ) {
1100     // Condition for convL2I(addL(x,y)) ==> addI(convL2I(x),convL2I(y))
1101     return n->Opcode() == Op_ConvL2I && n->in(1) == this;
1102   } else if( op == Op_SubI || op == Op_SubL ) {
1103     // Condition for subI(x,subI(y,z)) ==> subI(addI(x,z),y)
1104     return n->Opcode() == op && n->in(2) == this;
1105   }
1106   return false;
1107 };
1108 
1109 //--------------------------find_exact_control---------------------------------
1110 // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1111 Node* Node::find_exact_control(Node* ctrl) {
1112   if (ctrl == NULL && this->is_Region())
1113     ctrl = this->as_Region()->is_copy();
1114 
1115   if (ctrl != NULL && ctrl->is_CatchProj()) {
1116     if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1117       ctrl = ctrl->in(0);
1118     if (ctrl != NULL && !ctrl->is_top())
1119       ctrl = ctrl->in(0);
1120   }
1121 
1122   if (ctrl != NULL && ctrl->is_Proj())
1123     ctrl = ctrl->in(0);
1124 
1125   return ctrl;
1126 }
1127 
1128 //--------------------------dominates------------------------------------------
1129 // Helper function for MemNode::all_controls_dominate().
1130 // Check if 'this' control node dominates or equal to 'sub' control node.
1131 // We already know that if any path back to Root or Start reaches 'this',
1132 // then all paths so, so this is a simple search for one example,
1133 // not an exhaustive search for a counterexample.
1134 bool Node::dominates(Node* sub, Node_List &nlist) {
1135   assert(this->is_CFG(), "expecting control");
1136   assert(sub != NULL && sub->is_CFG(), "expecting control");
1137 
1138   // detect dead cycle without regions
1139   int iterations_without_region_limit = DominatorSearchLimit;
1140 
1141   Node* orig_sub = sub;
1142   Node* dom      = this;
1143   bool  met_dom  = false;
1144   nlist.clear();
1145 
1146   // Walk 'sub' backward up the chain to 'dom', watching for regions.
1147   // After seeing 'dom', continue up to Root or Start.
1148   // If we hit a region (backward split point), it may be a loop head.
1149   // Keep going through one of the region's inputs.  If we reach the
1150   // same region again, go through a different input.  Eventually we
1151   // will either exit through the loop head, or give up.
1152   // (If we get confused, break out and return a conservative 'false'.)
1153   while (sub != NULL) {
1154     if (sub->is_top())  break; // Conservative answer for dead code.
1155     if (sub == dom) {
1156       if (nlist.size() == 0) {
1157         // No Region nodes except loops were visited before and the EntryControl
1158         // path was taken for loops: it did not walk in a cycle.
1159         return true;
1160       } else if (met_dom) {
1161         break;          // already met before: walk in a cycle
1162       } else {
1163         // Region nodes were visited. Continue walk up to Start or Root
1164         // to make sure that it did not walk in a cycle.
1165         met_dom = true; // first time meet
1166         iterations_without_region_limit = DominatorSearchLimit; // Reset
1167      }
1168     }
1169     if (sub->is_Start() || sub->is_Root()) {
1170       // Success if we met 'dom' along a path to Start or Root.
1171       // We assume there are no alternative paths that avoid 'dom'.
1172       // (This assumption is up to the caller to ensure!)
1173       return met_dom;
1174     }
1175     Node* up = sub->in(0);
1176     // Normalize simple pass-through regions and projections:
1177     up = sub->find_exact_control(up);
1178     // If sub == up, we found a self-loop.  Try to push past it.
1179     if (sub == up && sub->is_Loop()) {
1180       // Take loop entry path on the way up to 'dom'.
1181       up = sub->in(1); // in(LoopNode::EntryControl);
1182     } else if (sub == up && sub->is_Region() && sub->req() != 3) {
1183       // Always take in(1) path on the way up to 'dom' for clone regions
1184       // (with only one input) or regions which merge > 2 paths
1185       // (usually used to merge fast/slow paths).
1186       up = sub->in(1);
1187     } else if (sub == up && sub->is_Region()) {
1188       // Try both paths for Regions with 2 input paths (it may be a loop head).
1189       // It could give conservative 'false' answer without information
1190       // which region's input is the entry path.
1191       iterations_without_region_limit = DominatorSearchLimit; // Reset
1192 
1193       bool region_was_visited_before = false;
1194       // Was this Region node visited before?
1195       // If so, we have reached it because we accidentally took a
1196       // loop-back edge from 'sub' back into the body of the loop,
1197       // and worked our way up again to the loop header 'sub'.
1198       // So, take the first unexplored path on the way up to 'dom'.
1199       for (int j = nlist.size() - 1; j >= 0; j--) {
1200         intptr_t ni = (intptr_t)nlist.at(j);
1201         Node* visited = (Node*)(ni & ~1);
1202         bool  visited_twice_already = ((ni & 1) != 0);
1203         if (visited == sub) {
1204           if (visited_twice_already) {
1205             // Visited 2 paths, but still stuck in loop body.  Give up.
1206             return false;
1207           }
1208           // The Region node was visited before only once.
1209           // (We will repush with the low bit set, below.)
1210           nlist.remove(j);
1211           // We will find a new edge and re-insert.
1212           region_was_visited_before = true;
1213           break;
1214         }
1215       }
1216 
1217       // Find an incoming edge which has not been seen yet; walk through it.
1218       assert(up == sub, "");
1219       uint skip = region_was_visited_before ? 1 : 0;
1220       for (uint i = 1; i < sub->req(); i++) {
1221         Node* in = sub->in(i);
1222         if (in != NULL && !in->is_top() && in != sub) {
1223           if (skip == 0) {
1224             up = in;
1225             break;
1226           }
1227           --skip;               // skip this nontrivial input
1228         }
1229       }
1230 
1231       // Set 0 bit to indicate that both paths were taken.
1232       nlist.push((Node*)((intptr_t)sub + (region_was_visited_before ? 1 : 0)));
1233     }
1234 
1235     if (up == sub) {
1236       break;    // some kind of tight cycle
1237     }
1238     if (up == orig_sub && met_dom) {
1239       // returned back after visiting 'dom'
1240       break;    // some kind of cycle
1241     }
1242     if (--iterations_without_region_limit < 0) {
1243       break;    // dead cycle
1244     }
1245     sub = up;
1246   }
1247 
1248   // Did not meet Root or Start node in pred. chain.
1249   // Conservative answer for dead code.
1250   return false;
1251 }
1252 
1253 //------------------------------remove_dead_region-----------------------------
1254 // This control node is dead.  Follow the subgraph below it making everything
1255 // using it dead as well.  This will happen normally via the usual IterGVN
1256 // worklist but this call is more efficient.  Do not update use-def info
1257 // inside the dead region, just at the borders.
1258 static void kill_dead_code( Node *dead, PhaseIterGVN *igvn ) {
1259   // Con's are a popular node to re-hit in the hash table again.
1260   if( dead->is_Con() ) return;
1261 
1262   // Can't put ResourceMark here since igvn->_worklist uses the same arena
1263   // for verify pass with +VerifyOpto and we add/remove elements in it here.
1264   Node_List  nstack(Thread::current()->resource_area());
1265 
1266   Node *top = igvn->C->top();
1267   nstack.push(dead);
1268   bool has_irreducible_loop = igvn->C->has_irreducible_loop();
1269 
1270   while (nstack.size() > 0) {
1271     dead = nstack.pop();
1272     if (dead->outcnt() > 0) {
1273       // Keep dead node on stack until all uses are processed.
1274       nstack.push(dead);
1275       // For all Users of the Dead...    ;-)
1276       for (DUIterator_Last kmin, k = dead->last_outs(kmin); k >= kmin; ) {
1277         Node* use = dead->last_out(k);
1278         igvn->hash_delete(use);       // Yank from hash table prior to mod
1279         if (use->in(0) == dead) {     // Found another dead node
1280           assert (!use->is_Con(), "Control for Con node should be Root node.");
1281           use->set_req(0, top);       // Cut dead edge to prevent processing
1282           nstack.push(use);           // the dead node again.
1283         } else if (!has_irreducible_loop && // Backedge could be alive in irreducible loop
1284                    use->is_Loop() && !use->is_Root() &&       // Don't kill Root (RootNode extends LoopNode)
1285                    use->in(LoopNode::EntryControl) == dead) { // Dead loop if its entry is dead
1286           use->set_req(LoopNode::EntryControl, top);          // Cut dead edge to prevent processing
1287           use->set_req(0, top);       // Cut self edge
1288           nstack.push(use);
1289         } else {                      // Else found a not-dead user
1290           // Dead if all inputs are top or null
1291           bool dead_use = !use->is_Root(); // Keep empty graph alive
1292           for (uint j = 1; j < use->req(); j++) {
1293             Node* in = use->in(j);
1294             if (in == dead) {         // Turn all dead inputs into TOP
1295               use->set_req(j, top);
1296             } else if (in != NULL && !in->is_top()) {
1297               dead_use = false;
1298             }
1299           }
1300           if (dead_use) {
1301             if (use->is_Region()) {
1302               use->set_req(0, top);   // Cut self edge
1303             }
1304             nstack.push(use);
1305           } else {
1306             igvn->_worklist.push(use);
1307           }
1308         }
1309         // Refresh the iterator, since any number of kills might have happened.
1310         k = dead->last_outs(kmin);
1311       }
1312     } else { // (dead->outcnt() == 0)
1313       // Done with outputs.
1314       igvn->hash_delete(dead);
1315       igvn->_worklist.remove(dead);
1316       igvn->set_type(dead, Type::TOP);
1317       if (dead->is_macro()) {
1318         igvn->C->remove_macro_node(dead);
1319       }
1320       if (dead->is_expensive()) {
1321         igvn->C->remove_expensive_node(dead);
1322       }
1323       igvn->C->record_dead_node(dead->_idx);
1324       // Kill all inputs to the dead guy
1325       for (uint i=0; i < dead->req(); i++) {
1326         Node *n = dead->in(i);      // Get input to dead guy
1327         if (n != NULL && !n->is_top()) { // Input is valid?
1328           dead->set_req(i, top);    // Smash input away
1329           if (n->outcnt() == 0) {   // Input also goes dead?
1330             if (!n->is_Con())
1331               nstack.push(n);       // Clear it out as well
1332           } else if (n->outcnt() == 1 &&
1333                      n->has_special_unique_user()) {
1334             igvn->add_users_to_worklist( n );
1335           } else if (n->outcnt() <= 2 && n->is_Store()) {
1336             // Push store's uses on worklist to enable folding optimization for
1337             // store/store and store/load to the same address.
1338             // The restriction (outcnt() <= 2) is the same as in set_req_X()
1339             // and remove_globally_dead_node().
1340             igvn->add_users_to_worklist( n );
1341           }
1342         }
1343       }
1344     } // (dead->outcnt() == 0)
1345   }   // while (nstack.size() > 0) for outputs
1346   return;
1347 }
1348 
1349 //------------------------------remove_dead_region-----------------------------
1350 bool Node::remove_dead_region(PhaseGVN *phase, bool can_reshape) {
1351   Node *n = in(0);
1352   if( !n ) return false;
1353   // Lost control into this guy?  I.e., it became unreachable?
1354   // Aggressively kill all unreachable code.
1355   if (can_reshape && n->is_top()) {
1356     kill_dead_code(this, phase->is_IterGVN());
1357     return false; // Node is dead.
1358   }
1359 
1360   if( n->is_Region() && n->as_Region()->is_copy() ) {
1361     Node *m = n->nonnull_req();
1362     set_req(0, m);
1363     return true;
1364   }
1365   return false;
1366 }
1367 
1368 //------------------------------Ideal_DU_postCCP-------------------------------
1369 // Idealize graph, using DU info.  Must clone result into new-space
1370 Node *Node::Ideal_DU_postCCP( PhaseCCP * ) {
1371   return NULL;                 // Default to no change
1372 }
1373 
1374 //------------------------------hash-------------------------------------------
1375 // Hash function over Nodes.
1376 uint Node::hash() const {
1377   uint sum = 0;
1378   for( uint i=0; i<_cnt; i++ )  // Add in all inputs
1379     sum = (sum<<1)-(uintptr_t)in(i);        // Ignore embedded NULLs
1380   return (sum>>2) + _cnt + Opcode();
1381 }
1382 
1383 //------------------------------cmp--------------------------------------------
1384 // Compare special parts of simple Nodes
1385 uint Node::cmp( const Node &n ) const {
1386   return 1;                     // Must be same
1387 }
1388 
1389 //------------------------------rematerialize-----------------------------------
1390 // Should we clone rather than spill this instruction?
1391 bool Node::rematerialize() const {
1392   if ( is_Mach() )
1393     return this->as_Mach()->rematerialize();
1394   else
1395     return (_flags & Flag_rematerialize) != 0;
1396 }
1397 
1398 //------------------------------needs_anti_dependence_check---------------------
1399 // Nodes which use memory without consuming it, hence need antidependences.
1400 bool Node::needs_anti_dependence_check() const {
1401   if( req() < 2 || (_flags & Flag_needs_anti_dependence_check) == 0 )
1402     return false;
1403   else
1404     return in(1)->bottom_type()->has_memory();
1405 }
1406 
1407 
1408 // Get an integer constant from a ConNode (or CastIINode).
1409 // Return a default value if there is no apparent constant here.
1410 const TypeInt* Node::find_int_type() const {
1411   if (this->is_Type()) {
1412     return this->as_Type()->type()->isa_int();
1413   } else if (this->is_Con()) {
1414     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1415     return this->bottom_type()->isa_int();
1416   }
1417   return NULL;
1418 }
1419 
1420 // Get a pointer constant from a ConstNode.
1421 // Returns the constant if it is a pointer ConstNode
1422 intptr_t Node::get_ptr() const {
1423   assert( Opcode() == Op_ConP, "" );
1424   return ((ConPNode*)this)->type()->is_ptr()->get_con();
1425 }
1426 
1427 // Get a narrow oop constant from a ConNNode.
1428 intptr_t Node::get_narrowcon() const {
1429   assert( Opcode() == Op_ConN, "" );
1430   return ((ConNNode*)this)->type()->is_narrowoop()->get_con();
1431 }
1432 
1433 // Get a long constant from a ConNode.
1434 // Return a default value if there is no apparent constant here.
1435 const TypeLong* Node::find_long_type() const {
1436   if (this->is_Type()) {
1437     return this->as_Type()->type()->isa_long();
1438   } else if (this->is_Con()) {
1439     assert(is_Mach(), "should be ConNode(TypeNode) or else a MachNode");
1440     return this->bottom_type()->isa_long();
1441   }
1442   return NULL;
1443 }
1444 
1445 
1446 /**
1447  * Return a ptr type for nodes which should have it.
1448  */
1449 const TypePtr* Node::get_ptr_type() const {
1450   const TypePtr* tp = this->bottom_type()->make_ptr();
1451 #ifdef ASSERT
1452   if (tp == NULL) {
1453     this->dump(1);
1454     assert((tp != NULL), "unexpected node type");
1455   }
1456 #endif
1457   return tp;
1458 }
1459 
1460 // Get a double constant from a ConstNode.
1461 // Returns the constant if it is a double ConstNode
1462 jdouble Node::getd() const {
1463   assert( Opcode() == Op_ConD, "" );
1464   return ((ConDNode*)this)->type()->is_double_constant()->getd();
1465 }
1466 
1467 // Get a float constant from a ConstNode.
1468 // Returns the constant if it is a float ConstNode
1469 jfloat Node::getf() const {
1470   assert( Opcode() == Op_ConF, "" );
1471   return ((ConFNode*)this)->type()->is_float_constant()->getf();
1472 }
1473 
1474 #ifndef PRODUCT
1475 
1476 //----------------------------NotANode----------------------------------------
1477 // Used in debugging code to avoid walking across dead or uninitialized edges.
1478 static inline bool NotANode(const Node* n) {
1479   if (n == NULL)                   return true;
1480   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
1481   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
1482   return false;
1483 }
1484 
1485 
1486 //------------------------------find------------------------------------------
1487 // Find a neighbor of this Node with the given _idx
1488 // If idx is negative, find its absolute value, following both _in and _out.
1489 static void find_recur(Compile* C,  Node* &result, Node *n, int idx, bool only_ctrl,
1490                         VectorSet* old_space, VectorSet* new_space ) {
1491   int node_idx = (idx >= 0) ? idx : -idx;
1492   if (NotANode(n))  return;  // Gracefully handle NULL, -1, 0xabababab, etc.
1493   // Contained in new_space or old_space?   Check old_arena first since it's mostly empty.
1494   VectorSet *v = C->old_arena()->contains(n) ? old_space : new_space;
1495   if( v->test(n->_idx) ) return;
1496   if( (int)n->_idx == node_idx
1497       debug_only(|| n->debug_idx() == node_idx) ) {
1498     if (result != NULL)
1499       tty->print("find: " INTPTR_FORMAT " and " INTPTR_FORMAT " both have idx==%d\n",
1500                  (uintptr_t)result, (uintptr_t)n, node_idx);
1501     result = n;
1502   }
1503   v->set(n->_idx);
1504   for( uint i=0; i<n->len(); i++ ) {
1505     if( only_ctrl && !(n->is_Region()) && (n->Opcode() != Op_Root) && (i != TypeFunc::Control) ) continue;
1506     find_recur(C, result, n->in(i), idx, only_ctrl, old_space, new_space );
1507   }
1508   // Search along forward edges also:
1509   if (idx < 0 && !only_ctrl) {
1510     for( uint j=0; j<n->outcnt(); j++ ) {
1511       find_recur(C, result, n->raw_out(j), idx, only_ctrl, old_space, new_space );
1512     }
1513   }
1514 #ifdef ASSERT
1515   // Search along debug_orig edges last, checking for cycles
1516   Node* orig = n->debug_orig();
1517   if (orig != NULL) {
1518     do {
1519       if (NotANode(orig))  break;
1520       find_recur(C, result, orig, idx, only_ctrl, old_space, new_space );
1521       orig = orig->debug_orig();
1522     } while (orig != NULL && orig != n->debug_orig());
1523   }
1524 #endif //ASSERT
1525 }
1526 
1527 // call this from debugger:
1528 Node* find_node(Node* n, int idx) {
1529   return n->find(idx);
1530 }
1531 
1532 //------------------------------find-------------------------------------------
1533 Node* Node::find(int idx) const {
1534   ResourceArea *area = Thread::current()->resource_area();
1535   VectorSet old_space(area), new_space(area);
1536   Node* result = NULL;
1537   find_recur(Compile::current(), result, (Node*) this, idx, false, &old_space, &new_space );
1538   return result;
1539 }
1540 
1541 //------------------------------find_ctrl--------------------------------------
1542 // Find an ancestor to this node in the control history with given _idx
1543 Node* Node::find_ctrl(int idx) const {
1544   ResourceArea *area = Thread::current()->resource_area();
1545   VectorSet old_space(area), new_space(area);
1546   Node* result = NULL;
1547   find_recur(Compile::current(), result, (Node*) this, idx, true, &old_space, &new_space );
1548   return result;
1549 }
1550 #endif
1551 
1552 
1553 
1554 #ifndef PRODUCT
1555 
1556 // -----------------------------Name-------------------------------------------
1557 extern const char *NodeClassNames[];
1558 const char *Node::Name() const { return NodeClassNames[Opcode()]; }
1559 
1560 static bool is_disconnected(const Node* n) {
1561   for (uint i = 0; i < n->req(); i++) {
1562     if (n->in(i) != NULL)  return false;
1563   }
1564   return true;
1565 }
1566 
1567 #ifdef ASSERT
1568 static void dump_orig(Node* orig, outputStream *st) {
1569   Compile* C = Compile::current();
1570   if (NotANode(orig)) orig = NULL;
1571   if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1572   if (orig == NULL) return;
1573   st->print(" !orig=");
1574   Node* fast = orig->debug_orig(); // tortoise & hare algorithm to detect loops
1575   if (NotANode(fast)) fast = NULL;
1576   while (orig != NULL) {
1577     bool discon = is_disconnected(orig);  // if discon, print [123] else 123
1578     if (discon) st->print("[");
1579     if (!Compile::current()->node_arena()->contains(orig))
1580       st->print("o");
1581     st->print("%d", orig->_idx);
1582     if (discon) st->print("]");
1583     orig = orig->debug_orig();
1584     if (NotANode(orig)) orig = NULL;
1585     if (orig != NULL && !C->node_arena()->contains(orig)) orig = NULL;
1586     if (orig != NULL) st->print(",");
1587     if (fast != NULL) {
1588       // Step fast twice for each single step of orig:
1589       fast = fast->debug_orig();
1590       if (NotANode(fast)) fast = NULL;
1591       if (fast != NULL && fast != orig) {
1592         fast = fast->debug_orig();
1593         if (NotANode(fast)) fast = NULL;
1594       }
1595       if (fast == orig) {
1596         st->print("...");
1597         break;
1598       }
1599     }
1600   }
1601 }
1602 
1603 void Node::set_debug_orig(Node* orig) {
1604   _debug_orig = orig;
1605   if (BreakAtNode == 0)  return;
1606   if (NotANode(orig))  orig = NULL;
1607   int trip = 10;
1608   while (orig != NULL) {
1609     if (orig->debug_idx() == BreakAtNode || (int)orig->_idx == BreakAtNode) {
1610       tty->print_cr("BreakAtNode: _idx=%d _debug_idx=%d orig._idx=%d orig._debug_idx=%d",
1611                     this->_idx, this->debug_idx(), orig->_idx, orig->debug_idx());
1612       BREAKPOINT;
1613     }
1614     orig = orig->debug_orig();
1615     if (NotANode(orig))  orig = NULL;
1616     if (trip-- <= 0)  break;
1617   }
1618 }
1619 #endif //ASSERT
1620 
1621 //------------------------------dump------------------------------------------
1622 // Dump a Node
1623 void Node::dump(const char* suffix, outputStream *st) const {
1624   Compile* C = Compile::current();
1625   bool is_new = C->node_arena()->contains(this);
1626   C->_in_dump_cnt++;
1627   st->print("%c%d\t%s\t=== ", is_new ? ' ' : 'o', _idx, Name());
1628 
1629   // Dump the required and precedence inputs
1630   dump_req(st);
1631   dump_prec(st);
1632   // Dump the outputs
1633   dump_out(st);
1634 
1635   if (is_disconnected(this)) {
1636 #ifdef ASSERT
1637     st->print("  [%d]",debug_idx());
1638     dump_orig(debug_orig(), st);
1639 #endif
1640     st->cr();
1641     C->_in_dump_cnt--;
1642     return;                     // don't process dead nodes
1643   }
1644 
1645   // Dump node-specific info
1646   dump_spec(st);
1647 #ifdef ASSERT
1648   // Dump the non-reset _debug_idx
1649   if (Verbose && WizardMode) {
1650     st->print("  [%d]",debug_idx());
1651   }
1652 #endif
1653 
1654   const Type *t = bottom_type();
1655 
1656   if (t != NULL && (t->isa_instptr() || t->isa_klassptr())) {
1657     const TypeInstPtr  *toop = t->isa_instptr();
1658     const TypeKlassPtr *tkls = t->isa_klassptr();
1659     ciKlass*           klass = toop ? toop->klass() : (tkls ? tkls->klass() : NULL );
1660     if (klass && klass->is_loaded() && klass->is_interface()) {
1661       st->print("  Interface:");
1662     } else if (toop) {
1663       st->print("  Oop:");
1664     } else if (tkls) {
1665       st->print("  Klass:");
1666     }
1667     t->dump_on(st);
1668   } else if (t == Type::MEMORY) {
1669     st->print("  Memory:");
1670     MemNode::dump_adr_type(this, adr_type(), st);
1671   } else if (Verbose || WizardMode) {
1672     st->print("  Type:");
1673     if (t) {
1674       t->dump_on(st);
1675     } else {
1676       st->print("no type");
1677     }
1678   } else if (t->isa_vect() && this->is_MachSpillCopy()) {
1679     // Dump MachSpillcopy vector type.
1680     t->dump_on(st);
1681   }
1682   if (is_new) {
1683     debug_only(dump_orig(debug_orig(), st));
1684     Node_Notes* nn = C->node_notes_at(_idx);
1685     if (nn != NULL && !nn->is_clear()) {
1686       if (nn->jvms() != NULL) {
1687         st->print(" !jvms:");
1688         nn->jvms()->dump_spec(st);
1689       }
1690     }
1691   }
1692   if (suffix) st->print("%s", suffix);
1693   C->_in_dump_cnt--;
1694 }
1695 
1696 //------------------------------dump_req--------------------------------------
1697 void Node::dump_req(outputStream *st) const {
1698   // Dump the required input edges
1699   for (uint i = 0; i < req(); i++) {    // For all required inputs
1700     Node* d = in(i);
1701     if (d == NULL) {
1702       st->print("_ ");
1703     } else if (NotANode(d)) {
1704       st->print("NotANode ");  // uninitialized, sentinel, garbage, etc.
1705     } else {
1706       st->print("%c%d ", Compile::current()->node_arena()->contains(d) ? ' ' : 'o', d->_idx);
1707     }
1708   }
1709 }
1710 
1711 
1712 //------------------------------dump_prec-------------------------------------
1713 void Node::dump_prec(outputStream *st) const {
1714   // Dump the precedence edges
1715   int any_prec = 0;
1716   for (uint i = req(); i < len(); i++) {       // For all precedence inputs
1717     Node* p = in(i);
1718     if (p != NULL) {
1719       if (!any_prec++) st->print(" |");
1720       if (NotANode(p)) { st->print("NotANode "); continue; }
1721       st->print("%c%d ", Compile::current()->node_arena()->contains(in(i)) ? ' ' : 'o', in(i)->_idx);
1722     }
1723   }
1724 }
1725 
1726 //------------------------------dump_out--------------------------------------
1727 void Node::dump_out(outputStream *st) const {
1728   // Delimit the output edges
1729   st->print(" [[");
1730   // Dump the output edges
1731   for (uint i = 0; i < _outcnt; i++) {    // For all outputs
1732     Node* u = _out[i];
1733     if (u == NULL) {
1734       st->print("_ ");
1735     } else if (NotANode(u)) {
1736       st->print("NotANode ");
1737     } else {
1738       st->print("%c%d ", Compile::current()->node_arena()->contains(u) ? ' ' : 'o', u->_idx);
1739     }
1740   }
1741   st->print("]] ");
1742 }
1743 
1744 //------------------------------dump_nodes-------------------------------------
1745 static void dump_nodes(const Node* start, int d, bool only_ctrl) {
1746   Node* s = (Node*)start; // remove const
1747   if (NotANode(s)) return;
1748 
1749   uint depth = (uint)ABS(d);
1750   int direction = d;
1751   Compile* C = Compile::current();
1752   GrowableArray <Node *> nstack(C->unique());
1753 
1754   nstack.append(s);
1755   int begin = 0;
1756   int end = 0;
1757   for(uint i = 0; i < depth; i++) {
1758     end = nstack.length();
1759     for(int j = begin; j < end; j++) {
1760       Node* tp  = nstack.at(j);
1761       uint limit = direction > 0 ? tp->len() : tp->outcnt();
1762       for(uint k = 0; k < limit; k++) {
1763         Node* n = direction > 0 ? tp->in(k) : tp->raw_out(k);
1764 
1765         if (NotANode(n))  continue;
1766         // do not recurse through top or the root (would reach unrelated stuff)
1767         if (n->is_Root() || n->is_top())  continue;
1768         if (only_ctrl && !n->is_CFG()) continue;
1769 
1770         bool on_stack = nstack.contains(n);
1771         if (!on_stack) {
1772           nstack.append(n);
1773         }
1774       }
1775     }
1776     begin = end;
1777   }
1778   end = nstack.length();
1779   if (direction > 0) {
1780     for(int j = end-1; j >= 0; j--) {
1781       nstack.at(j)->dump();
1782     }
1783   } else {
1784     for(int j = 0; j < end; j++) {
1785       nstack.at(j)->dump();
1786     }
1787   }
1788 }
1789 
1790 //------------------------------dump-------------------------------------------
1791 void Node::dump(int d) const {
1792   dump_nodes(this, d, false);
1793 }
1794 
1795 //------------------------------dump_ctrl--------------------------------------
1796 // Dump a Node's control history to depth
1797 void Node::dump_ctrl(int d) const {
1798   dump_nodes(this, d, true);
1799 }
1800 
1801 // VERIFICATION CODE
1802 // For each input edge to a node (ie - for each Use-Def edge), verify that
1803 // there is a corresponding Def-Use edge.
1804 //------------------------------verify_edges-----------------------------------
1805 void Node::verify_edges(Unique_Node_List &visited) {
1806   uint i, j, idx;
1807   int  cnt;
1808   Node *n;
1809 
1810   // Recursive termination test
1811   if (visited.member(this))  return;
1812   visited.push(this);
1813 
1814   // Walk over all input edges, checking for correspondence
1815   for( i = 0; i < len(); i++ ) {
1816     n = in(i);
1817     if (n != NULL && !n->is_top()) {
1818       // Count instances of (Node *)this
1819       cnt = 0;
1820       for (idx = 0; idx < n->_outcnt; idx++ ) {
1821         if (n->_out[idx] == (Node *)this)  cnt++;
1822       }
1823       assert( cnt > 0,"Failed to find Def-Use edge." );
1824       // Check for duplicate edges
1825       // walk the input array downcounting the input edges to n
1826       for( j = 0; j < len(); j++ ) {
1827         if( in(j) == n ) cnt--;
1828       }
1829       assert( cnt == 0,"Mismatched edge count.");
1830     } else if (n == NULL) {
1831       assert(i >= req() || i == 0 || is_Region() || is_Phi(), "only regions or phis have null data edges");
1832     } else {
1833       assert(n->is_top(), "sanity");
1834       // Nothing to check.
1835     }
1836   }
1837   // Recursive walk over all input edges
1838   for( i = 0; i < len(); i++ ) {
1839     n = in(i);
1840     if( n != NULL )
1841       in(i)->verify_edges(visited);
1842   }
1843 }
1844 
1845 //------------------------------verify_recur-----------------------------------
1846 static const Node *unique_top = NULL;
1847 
1848 void Node::verify_recur(const Node *n, int verify_depth,
1849                         VectorSet &old_space, VectorSet &new_space) {
1850   if ( verify_depth == 0 )  return;
1851   if (verify_depth > 0)  --verify_depth;
1852 
1853   Compile* C = Compile::current();
1854 
1855   // Contained in new_space or old_space?
1856   VectorSet *v = C->node_arena()->contains(n) ? &new_space : &old_space;
1857   // Check for visited in the proper space.  Numberings are not unique
1858   // across spaces so we need a separate VectorSet for each space.
1859   if( v->test_set(n->_idx) ) return;
1860 
1861   if (n->is_Con() && n->bottom_type() == Type::TOP) {
1862     if (C->cached_top_node() == NULL)
1863       C->set_cached_top_node((Node*)n);
1864     assert(C->cached_top_node() == n, "TOP node must be unique");
1865   }
1866 
1867   for( uint i = 0; i < n->len(); i++ ) {
1868     Node *x = n->in(i);
1869     if (!x || x->is_top()) continue;
1870 
1871     // Verify my input has a def-use edge to me
1872     if (true /*VerifyDefUse*/) {
1873       // Count use-def edges from n to x
1874       int cnt = 0;
1875       for( uint j = 0; j < n->len(); j++ )
1876         if( n->in(j) == x )
1877           cnt++;
1878       // Count def-use edges from x to n
1879       uint max = x->_outcnt;
1880       for( uint k = 0; k < max; k++ )
1881         if (x->_out[k] == n)
1882           cnt--;
1883       assert( cnt == 0, "mismatched def-use edge counts" );
1884     }
1885 
1886     verify_recur(x, verify_depth, old_space, new_space);
1887   }
1888 
1889 }
1890 
1891 //------------------------------verify-----------------------------------------
1892 // Check Def-Use info for my subgraph
1893 void Node::verify() const {
1894   Compile* C = Compile::current();
1895   Node* old_top = C->cached_top_node();
1896   ResourceMark rm;
1897   ResourceArea *area = Thread::current()->resource_area();
1898   VectorSet old_space(area), new_space(area);
1899   verify_recur(this, -1, old_space, new_space);
1900   C->set_cached_top_node(old_top);
1901 }
1902 #endif
1903 
1904 
1905 //------------------------------walk-------------------------------------------
1906 // Graph walk, with both pre-order and post-order functions
1907 void Node::walk(NFunc pre, NFunc post, void *env) {
1908   VectorSet visited(Thread::current()->resource_area()); // Setup for local walk
1909   walk_(pre, post, env, visited);
1910 }
1911 
1912 void Node::walk_(NFunc pre, NFunc post, void *env, VectorSet &visited) {
1913   if( visited.test_set(_idx) ) return;
1914   pre(*this,env);               // Call the pre-order walk function
1915   for( uint i=0; i<_max; i++ )
1916     if( in(i) )                 // Input exists and is not walked?
1917       in(i)->walk_(pre,post,env,visited); // Walk it with pre & post functions
1918   post(*this,env);              // Call the post-order walk function
1919 }
1920 
1921 void Node::nop(Node &, void*) {}
1922 
1923 //------------------------------Registers--------------------------------------
1924 // Do we Match on this edge index or not?  Generally false for Control
1925 // and true for everything else.  Weird for calls & returns.
1926 uint Node::match_edge(uint idx) const {
1927   return idx;                   // True for other than index 0 (control)
1928 }
1929 
1930 static RegMask _not_used_at_all;
1931 // Register classes are defined for specific machines
1932 const RegMask &Node::out_RegMask() const {
1933   ShouldNotCallThis();
1934   return _not_used_at_all;
1935 }
1936 
1937 const RegMask &Node::in_RegMask(uint) const {
1938   ShouldNotCallThis();
1939   return _not_used_at_all;
1940 }
1941 
1942 //=============================================================================
1943 //-----------------------------------------------------------------------------
1944 void Node_Array::reset( Arena *new_arena ) {
1945   _a->Afree(_nodes,_max*sizeof(Node*));
1946   _max   = 0;
1947   _nodes = NULL;
1948   _a     = new_arena;
1949 }
1950 
1951 //------------------------------clear------------------------------------------
1952 // Clear all entries in _nodes to NULL but keep storage
1953 void Node_Array::clear() {
1954   Copy::zero_to_bytes( _nodes, _max*sizeof(Node*) );
1955 }
1956 
1957 //-----------------------------------------------------------------------------
1958 void Node_Array::grow( uint i ) {
1959   if( !_max ) {
1960     _max = 1;
1961     _nodes = (Node**)_a->Amalloc( _max * sizeof(Node*) );
1962     _nodes[0] = NULL;
1963   }
1964   uint old = _max;
1965   while( i >= _max ) _max <<= 1;        // Double to fit
1966   _nodes = (Node**)_a->Arealloc( _nodes, old*sizeof(Node*),_max*sizeof(Node*));
1967   Copy::zero_to_bytes( &_nodes[old], (_max-old)*sizeof(Node*) );
1968 }
1969 
1970 //-----------------------------------------------------------------------------
1971 void Node_Array::insert( uint i, Node *n ) {
1972   if( _nodes[_max-1] ) grow(_max);      // Get more space if full
1973   Copy::conjoint_words_to_higher((HeapWord*)&_nodes[i], (HeapWord*)&_nodes[i+1], ((_max-i-1)*sizeof(Node*)));
1974   _nodes[i] = n;
1975 }
1976 
1977 //-----------------------------------------------------------------------------
1978 void Node_Array::remove( uint i ) {
1979   Copy::conjoint_words_to_lower((HeapWord*)&_nodes[i+1], (HeapWord*)&_nodes[i], ((_max-i-1)*sizeof(Node*)));
1980   _nodes[_max-1] = NULL;
1981 }
1982 
1983 //-----------------------------------------------------------------------------
1984 void Node_Array::sort( C_sort_func_t func) {
1985   qsort( _nodes, _max, sizeof( Node* ), func );
1986 }
1987 
1988 //-----------------------------------------------------------------------------
1989 void Node_Array::dump() const {
1990 #ifndef PRODUCT
1991   for( uint i = 0; i < _max; i++ ) {
1992     Node *nn = _nodes[i];
1993     if( nn != NULL ) {
1994       tty->print("%5d--> ",i); nn->dump();
1995     }
1996   }
1997 #endif
1998 }
1999 
2000 //--------------------------is_iteratively_computed------------------------------
2001 // Operation appears to be iteratively computed (such as an induction variable)
2002 // It is possible for this operation to return false for a loop-varying
2003 // value, if it appears (by local graph inspection) to be computed by a simple conditional.
2004 bool Node::is_iteratively_computed() {
2005   if (ideal_reg()) { // does operation have a result register?
2006     for (uint i = 1; i < req(); i++) {
2007       Node* n = in(i);
2008       if (n != NULL && n->is_Phi()) {
2009         for (uint j = 1; j < n->req(); j++) {
2010           if (n->in(j) == this) {
2011             return true;
2012           }
2013         }
2014       }
2015     }
2016   }
2017   return false;
2018 }
2019 
2020 //--------------------------find_similar------------------------------
2021 // Return a node with opcode "opc" and same inputs as "this" if one can
2022 // be found; Otherwise return NULL;
2023 Node* Node::find_similar(int opc) {
2024   if (req() >= 2) {
2025     Node* def = in(1);
2026     if (def && def->outcnt() >= 2) {
2027       for (DUIterator_Fast dmax, i = def->fast_outs(dmax); i < dmax; i++) {
2028         Node* use = def->fast_out(i);
2029         if (use->Opcode() == opc &&
2030             use->req() == req()) {
2031           uint j;
2032           for (j = 0; j < use->req(); j++) {
2033             if (use->in(j) != in(j)) {
2034               break;
2035             }
2036           }
2037           if (j == use->req()) {
2038             return use;
2039           }
2040         }
2041       }
2042     }
2043   }
2044   return NULL;
2045 }
2046 
2047 
2048 //--------------------------unique_ctrl_out------------------------------
2049 // Return the unique control out if only one. Null if none or more than one.
2050 Node* Node::unique_ctrl_out() {
2051   Node* found = NULL;
2052   for (uint i = 0; i < outcnt(); i++) {
2053     Node* use = raw_out(i);
2054     if (use->is_CFG() && use != this) {
2055       if (found != NULL) return NULL;
2056       found = use;
2057     }
2058   }
2059   return found;
2060 }
2061 
2062 //=============================================================================
2063 //------------------------------yank-------------------------------------------
2064 // Find and remove
2065 void Node_List::yank( Node *n ) {
2066   uint i;
2067   for( i = 0; i < _cnt; i++ )
2068     if( _nodes[i] == n )
2069       break;
2070 
2071   if( i < _cnt )
2072     _nodes[i] = _nodes[--_cnt];
2073 }
2074 
2075 //------------------------------dump-------------------------------------------
2076 void Node_List::dump() const {
2077 #ifndef PRODUCT
2078   for( uint i = 0; i < _cnt; i++ )
2079     if( _nodes[i] ) {
2080       tty->print("%5d--> ",i);
2081       _nodes[i]->dump();
2082     }
2083 #endif
2084 }
2085 
2086 //=============================================================================
2087 //------------------------------remove-----------------------------------------
2088 void Unique_Node_List::remove( Node *n ) {
2089   if( _in_worklist[n->_idx] ) {
2090     for( uint i = 0; i < size(); i++ )
2091       if( _nodes[i] == n ) {
2092         map(i,Node_List::pop());
2093         _in_worklist >>= n->_idx;
2094         return;
2095       }
2096     ShouldNotReachHere();
2097   }
2098 }
2099 
2100 //-----------------------remove_useless_nodes----------------------------------
2101 // Remove useless nodes from worklist
2102 void Unique_Node_List::remove_useless_nodes(VectorSet &useful) {
2103 
2104   for( uint i = 0; i < size(); ++i ) {
2105     Node *n = at(i);
2106     assert( n != NULL, "Did not expect null entries in worklist");
2107     if( ! useful.test(n->_idx) ) {
2108       _in_worklist >>= n->_idx;
2109       map(i,Node_List::pop());
2110       // Node *replacement = Node_List::pop();
2111       // if( i != size() ) { // Check if removing last entry
2112       //   _nodes[i] = replacement;
2113       // }
2114       --i;  // Visit popped node
2115       // If it was last entry, loop terminates since size() was also reduced
2116     }
2117   }
2118 }
2119 
2120 //=============================================================================
2121 void Node_Stack::grow() {
2122   size_t old_top = pointer_delta(_inode_top,_inodes,sizeof(INode)); // save _top
2123   size_t old_max = pointer_delta(_inode_max,_inodes,sizeof(INode));
2124   size_t max = old_max << 1;             // max * 2
2125   _inodes = REALLOC_ARENA_ARRAY(_a, INode, _inodes, old_max, max);
2126   _inode_max = _inodes + max;
2127   _inode_top = _inodes + old_top;        // restore _top
2128 }
2129 
2130 // Node_Stack is used to map nodes.
2131 Node* Node_Stack::find(uint idx) const {
2132   uint sz = size();
2133   for (uint i=0; i < sz; i++) {
2134     if (idx == index_at(i) )
2135       return node_at(i);
2136   }
2137   return NULL;
2138 }
2139 
2140 //=============================================================================
2141 uint TypeNode::size_of() const { return sizeof(*this); }
2142 #ifndef PRODUCT
2143 void TypeNode::dump_spec(outputStream *st) const {
2144   if( !Verbose && !WizardMode ) {
2145     // standard dump does this in Verbose and WizardMode
2146     st->print(" #"); _type->dump_on(st);
2147   }
2148 }
2149 #endif
2150 uint TypeNode::hash() const {
2151   return Node::hash() + _type->hash();
2152 }
2153 uint TypeNode::cmp( const Node &n ) const
2154 { return !Type::cmp( _type, ((TypeNode&)n)._type ); }
2155 const Type *TypeNode::bottom_type() const { return _type; }
2156 const Type *TypeNode::Value( PhaseTransform * ) const { return _type; }
2157 
2158 //------------------------------ideal_reg--------------------------------------
2159 uint TypeNode::ideal_reg() const {
2160   return _type->ideal_reg();
2161 }