1 /*
   2  * Copyright (c) 1997, 2018, 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 #ifndef SHARE_VM_OPTO_NODE_HPP
  26 #define SHARE_VM_OPTO_NODE_HPP
  27 
  28 #include "libadt/vectset.hpp"
  29 #include "opto/compile.hpp"
  30 #include "opto/type.hpp"
  31 
  32 // Portions of code courtesy of Clifford Click
  33 
  34 // Optimization - Graph Style
  35 
  36 
  37 class AbstractLockNode;
  38 class AddNode;
  39 class AddPNode;
  40 class AliasInfo;
  41 class AllocateArrayNode;
  42 class AllocateNode;
  43 class ArrayCopyNode;
  44 class Block;
  45 class BoolNode;
  46 class BoxLockNode;
  47 class CMoveNode;
  48 class CallDynamicJavaNode;
  49 class CallJavaNode;
  50 class CallLeafNode;
  51 class CallNode;
  52 class CallRuntimeNode;
  53 class CallStaticJavaNode;
  54 class CastIINode;
  55 class CastLLNode;
  56 class CatchNode;
  57 class CatchProjNode;
  58 class CheckCastPPNode;
  59 class ClearArrayNode;
  60 class CmpNode;
  61 class CodeBuffer;
  62 class ConstraintCastNode;
  63 class ConNode;
  64 class CompareAndSwapNode;
  65 class CompareAndExchangeNode;
  66 class CountedLoopNode;
  67 class CountedLoopEndNode;
  68 class DecodeNarrowPtrNode;
  69 class DecodeNNode;
  70 class DecodeNKlassNode;
  71 class EncodeNarrowPtrNode;
  72 class EncodePNode;
  73 class EncodePKlassNode;
  74 class FastLockNode;
  75 class FastUnlockNode;
  76 class IfNode;
  77 class IfProjNode;
  78 class IfFalseNode;
  79 class IfTrueNode;
  80 class InitializeNode;
  81 class JVMState;
  82 class JumpNode;
  83 class JumpProjNode;
  84 class LoadNode;
  85 class LoadBarrierNode;
  86 class LoadBarrierSlowRegNode;
  87 class LoadBarrierWeakSlowRegNode;
  88 class LoadStoreNode;
  89 class LockNode;
  90 class LoopNode;
  91 class MachBranchNode;
  92 class MachCallDynamicJavaNode;
  93 class MachCallJavaNode;
  94 class MachCallLeafNode;
  95 class MachCallNode;
  96 class MachCallRuntimeNode;
  97 class MachCallStaticJavaNode;
  98 class MachConstantBaseNode;
  99 class MachConstantNode;
 100 class MachGotoNode;
 101 class MachIfNode;
 102 class MachJumpNode;
 103 class MachNode;
 104 class MachNullCheckNode;
 105 class MachProjNode;
 106 class MachReturnNode;
 107 class MachSafePointNode;
 108 class MachSpillCopyNode;
 109 class MachTempNode;
 110 class MachMergeNode;
 111 class MachMemBarNode;
 112 class Matcher;
 113 class MemBarNode;
 114 class MemBarStoreStoreNode;
 115 class MemNode;
 116 class MergeMemNode;
 117 class MulNode;
 118 class MultiNode;
 119 class MultiBranchNode;
 120 class NeverBranchNode;
 121 class OuterStripMinedLoopNode;
 122 class OuterStripMinedLoopEndNode;
 123 class Node;
 124 class Node_Array;
 125 class Node_List;
 126 class Node_Stack;
 127 class NullCheckNode;
 128 class OopMap;
 129 class ParmNode;
 130 class PCTableNode;
 131 class PhaseCCP;
 132 class PhaseGVN;
 133 class PhaseIterGVN;
 134 class PhaseRegAlloc;
 135 class PhaseTransform;
 136 class PhaseValues;
 137 class PhiNode;
 138 class Pipeline;
 139 class ProjNode;
 140 class RangeCheckNode;
 141 class RegMask;
 142 class RegionNode;
 143 class RootNode;
 144 class SafePointNode;
 145 class SafePointScalarObjectNode;
 146 class StartNode;
 147 class State;
 148 class StoreNode;
 149 class SubNode;
 150 class Type;
 151 class TypeNode;
 152 class UnlockNode;
 153 class VectorNode;
 154 class LoadVectorNode;
 155 class StoreVectorNode;
 156 class VectorSet;
 157 typedef void (*NFunc)(Node&,void*);
 158 extern "C" {
 159   typedef int (*C_sort_func_t)(const void *, const void *);
 160 }
 161 
 162 // The type of all node counts and indexes.
 163 // It must hold at least 16 bits, but must also be fast to load and store.
 164 // This type, if less than 32 bits, could limit the number of possible nodes.
 165 // (To make this type platform-specific, move to globalDefinitions_xxx.hpp.)
 166 typedef unsigned int node_idx_t;
 167 
 168 
 169 #ifndef OPTO_DU_ITERATOR_ASSERT
 170 #ifdef ASSERT
 171 #define OPTO_DU_ITERATOR_ASSERT 1
 172 #else
 173 #define OPTO_DU_ITERATOR_ASSERT 0
 174 #endif
 175 #endif //OPTO_DU_ITERATOR_ASSERT
 176 
 177 #if OPTO_DU_ITERATOR_ASSERT
 178 class DUIterator;
 179 class DUIterator_Fast;
 180 class DUIterator_Last;
 181 #else
 182 typedef uint   DUIterator;
 183 typedef Node** DUIterator_Fast;
 184 typedef Node** DUIterator_Last;
 185 #endif
 186 
 187 // Node Sentinel
 188 #define NodeSentinel (Node*)-1
 189 
 190 // Unknown count frequency
 191 #define COUNT_UNKNOWN (-1.0f)
 192 
 193 //------------------------------Node-------------------------------------------
 194 // Nodes define actions in the program.  They create values, which have types.
 195 // They are both vertices in a directed graph and program primitives.  Nodes
 196 // are labeled; the label is the "opcode", the primitive function in the lambda
 197 // calculus sense that gives meaning to the Node.  Node inputs are ordered (so
 198 // that "a-b" is different from "b-a").  The inputs to a Node are the inputs to
 199 // the Node's function.  These inputs also define a Type equation for the Node.
 200 // Solving these Type equations amounts to doing dataflow analysis.
 201 // Control and data are uniformly represented in the graph.  Finally, Nodes
 202 // have a unique dense integer index which is used to index into side arrays
 203 // whenever I have phase-specific information.
 204 
 205 class Node {
 206   friend class VMStructs;
 207 
 208   // Lots of restrictions on cloning Nodes
 209   Node(const Node&);            // not defined; linker error to use these
 210   Node &operator=(const Node &rhs);
 211 
 212 public:
 213   friend class Compile;
 214   #if OPTO_DU_ITERATOR_ASSERT
 215   friend class DUIterator_Common;
 216   friend class DUIterator;
 217   friend class DUIterator_Fast;
 218   friend class DUIterator_Last;
 219   #endif
 220 
 221   // Because Nodes come and go, I define an Arena of Node structures to pull
 222   // from.  This should allow fast access to node creation & deletion.  This
 223   // field is a local cache of a value defined in some "program fragment" for
 224   // which these Nodes are just a part of.
 225 
 226   inline void* operator new(size_t x) throw() {
 227     Compile* C = Compile::current();
 228     Node* n = (Node*)C->node_arena()->Amalloc_D(x);
 229     return (void*)n;
 230   }
 231 
 232   // Delete is a NOP
 233   void operator delete( void *ptr ) {}
 234   // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 235   void destruct();
 236 
 237   // Create a new Node.  Required is the number is of inputs required for
 238   // semantic correctness.
 239   Node( uint required );
 240 
 241   // Create a new Node with given input edges.
 242   // This version requires use of the "edge-count" new.
 243   // E.g.  new (C,3) FooNode( C, NULL, left, right );
 244   Node( Node *n0 );
 245   Node( Node *n0, Node *n1 );
 246   Node( Node *n0, Node *n1, Node *n2 );
 247   Node( Node *n0, Node *n1, Node *n2, Node *n3 );
 248   Node( Node *n0, Node *n1, Node *n2, Node *n3, Node *n4 );
 249   Node( Node *n0, Node *n1, Node *n2, Node *n3, Node *n4, Node *n5 );
 250   Node( Node *n0, Node *n1, Node *n2, Node *n3,
 251             Node *n4, Node *n5, Node *n6 );
 252 
 253   // Clone an inherited Node given only the base Node type.
 254   Node* clone() const;
 255 
 256   // Clone a Node, immediately supplying one or two new edges.
 257   // The first and second arguments, if non-null, replace in(1) and in(2),
 258   // respectively.
 259   Node* clone_with_data_edge(Node* in1, Node* in2 = NULL) const {
 260     Node* nn = clone();
 261     if (in1 != NULL)  nn->set_req(1, in1);
 262     if (in2 != NULL)  nn->set_req(2, in2);
 263     return nn;
 264   }
 265 
 266 private:
 267   // Shared setup for the above constructors.
 268   // Handles all interactions with Compile::current.
 269   // Puts initial values in all Node fields except _idx.
 270   // Returns the initial value for _idx, which cannot
 271   // be initialized by assignment.
 272   inline int Init(int req);
 273 
 274 //----------------- input edge handling
 275 protected:
 276   friend class PhaseCFG;        // Access to address of _in array elements
 277   Node **_in;                   // Array of use-def references to Nodes
 278   Node **_out;                  // Array of def-use references to Nodes
 279 
 280   // Input edges are split into two categories.  Required edges are required
 281   // for semantic correctness; order is important and NULLs are allowed.
 282   // Precedence edges are used to help determine execution order and are
 283   // added, e.g., for scheduling purposes.  They are unordered and not
 284   // duplicated; they have no embedded NULLs.  Edges from 0 to _cnt-1
 285   // are required, from _cnt to _max-1 are precedence edges.
 286   node_idx_t _cnt;              // Total number of required Node inputs.
 287 
 288   node_idx_t _max;              // Actual length of input array.
 289 
 290   // Output edges are an unordered list of def-use edges which exactly
 291   // correspond to required input edges which point from other nodes
 292   // to this one.  Thus the count of the output edges is the number of
 293   // users of this node.
 294   node_idx_t _outcnt;           // Total number of Node outputs.
 295 
 296   node_idx_t _outmax;           // Actual length of output array.
 297 
 298   // Grow the actual input array to the next larger power-of-2 bigger than len.
 299   void grow( uint len );
 300   // Grow the output array to the next larger power-of-2 bigger than len.
 301   void out_grow( uint len );
 302 
 303  public:
 304   // Each Node is assigned a unique small/dense number.  This number is used
 305   // to index into auxiliary arrays of data and bit vectors.
 306   // The field _idx is declared constant to defend against inadvertent assignments,
 307   // since it is used by clients as a naked field. However, the field's value can be
 308   // changed using the set_idx() method.
 309   //
 310   // The PhaseRenumberLive phase renumbers nodes based on liveness information.
 311   // Therefore, it updates the value of the _idx field. The parse-time _idx is
 312   // preserved in _parse_idx.
 313   const node_idx_t _idx;
 314   DEBUG_ONLY(const node_idx_t _parse_idx;)
 315 
 316   // Get the (read-only) number of input edges
 317   uint req() const { return _cnt; }
 318   uint len() const { return _max; }
 319   // Get the (read-only) number of output edges
 320   uint outcnt() const { return _outcnt; }
 321 
 322 #if OPTO_DU_ITERATOR_ASSERT
 323   // Iterate over the out-edges of this node.  Deletions are illegal.
 324   inline DUIterator outs() const;
 325   // Use this when the out array might have changed to suppress asserts.
 326   inline DUIterator& refresh_out_pos(DUIterator& i) const;
 327   // Does the node have an out at this position?  (Used for iteration.)
 328   inline bool has_out(DUIterator& i) const;
 329   inline Node*    out(DUIterator& i) const;
 330   // Iterate over the out-edges of this node.  All changes are illegal.
 331   inline DUIterator_Fast fast_outs(DUIterator_Fast& max) const;
 332   inline Node*    fast_out(DUIterator_Fast& i) const;
 333   // Iterate over the out-edges of this node, deleting one at a time.
 334   inline DUIterator_Last last_outs(DUIterator_Last& min) const;
 335   inline Node*    last_out(DUIterator_Last& i) const;
 336   // The inline bodies of all these methods are after the iterator definitions.
 337 #else
 338   // Iterate over the out-edges of this node.  Deletions are illegal.
 339   // This iteration uses integral indexes, to decouple from array reallocations.
 340   DUIterator outs() const  { return 0; }
 341   // Use this when the out array might have changed to suppress asserts.
 342   DUIterator refresh_out_pos(DUIterator i) const { return i; }
 343 
 344   // Reference to the i'th output Node.  Error if out of bounds.
 345   Node*    out(DUIterator i) const { assert(i < _outcnt, "oob"); return _out[i]; }
 346   // Does the node have an out at this position?  (Used for iteration.)
 347   bool has_out(DUIterator i) const { return i < _outcnt; }
 348 
 349   // Iterate over the out-edges of this node.  All changes are illegal.
 350   // This iteration uses a pointer internal to the out array.
 351   DUIterator_Fast fast_outs(DUIterator_Fast& max) const {
 352     Node** out = _out;
 353     // Assign a limit pointer to the reference argument:
 354     max = out + (ptrdiff_t)_outcnt;
 355     // Return the base pointer:
 356     return out;
 357   }
 358   Node*    fast_out(DUIterator_Fast i) const  { return *i; }
 359   // Iterate over the out-edges of this node, deleting one at a time.
 360   // This iteration uses a pointer internal to the out array.
 361   DUIterator_Last last_outs(DUIterator_Last& min) const {
 362     Node** out = _out;
 363     // Assign a limit pointer to the reference argument:
 364     min = out;
 365     // Return the pointer to the start of the iteration:
 366     return out + (ptrdiff_t)_outcnt - 1;
 367   }
 368   Node*    last_out(DUIterator_Last i) const  { return *i; }
 369 #endif
 370 
 371   // Reference to the i'th input Node.  Error if out of bounds.
 372   Node* in(uint i) const { assert(i < _max, "oob: i=%d, _max=%d", i, _max); return _in[i]; }
 373   // Reference to the i'th input Node.  NULL if out of bounds.
 374   Node* lookup(uint i) const { return ((i < _max) ? _in[i] : NULL); }
 375   // Reference to the i'th output Node.  Error if out of bounds.
 376   // Use this accessor sparingly.  We are going trying to use iterators instead.
 377   Node* raw_out(uint i) const { assert(i < _outcnt,"oob"); return _out[i]; }
 378   // Return the unique out edge.
 379   Node* unique_out() const { assert(_outcnt==1,"not unique"); return _out[0]; }
 380   // Delete out edge at position 'i' by moving last out edge to position 'i'
 381   void  raw_del_out(uint i) {
 382     assert(i < _outcnt,"oob");
 383     assert(_outcnt > 0,"oob");
 384     #if OPTO_DU_ITERATOR_ASSERT
 385     // Record that a change happened here.
 386     debug_only(_last_del = _out[i]; ++_del_tick);
 387     #endif
 388     _out[i] = _out[--_outcnt];
 389     // Smash the old edge so it can't be used accidentally.
 390     debug_only(_out[_outcnt] = (Node *)(uintptr_t)0xdeadbeef);
 391   }
 392 
 393 #ifdef ASSERT
 394   bool is_dead() const;
 395 #define is_not_dead(n) ((n) == NULL || !VerifyIterativeGVN || !((n)->is_dead()))
 396   bool is_reachable_from_root() const;
 397 #endif
 398   // Check whether node has become unreachable
 399   bool is_unreachable(PhaseIterGVN &igvn) const;
 400 
 401   // Set a required input edge, also updates corresponding output edge
 402   void add_req( Node *n ); // Append a NEW required input
 403   void add_req( Node *n0, Node *n1 ) {
 404     add_req(n0); add_req(n1); }
 405   void add_req( Node *n0, Node *n1, Node *n2 ) {
 406     add_req(n0); add_req(n1); add_req(n2); }
 407   void add_req_batch( Node* n, uint m ); // Append m NEW required inputs (all n).
 408   void del_req( uint idx ); // Delete required edge & compact
 409   void del_req_ordered( uint idx ); // Delete required edge & compact with preserved order
 410   void ins_req( uint i, Node *n ); // Insert a NEW required input
 411   void set_req( uint i, Node *n ) {
 412     assert( is_not_dead(n), "can not use dead node");
 413     assert( i < _cnt, "oob: i=%d, _cnt=%d", i, _cnt);
 414     assert( !VerifyHashTableKeys || _hash_lock == 0,
 415             "remove node from hash table before modifying it");
 416     Node** p = &_in[i];    // cache this._in, across the del_out call
 417     if (*p != NULL)  (*p)->del_out((Node *)this);
 418     (*p) = n;
 419     if (n != NULL)      n->add_out((Node *)this);
 420     Compile::current()->record_modified_node(this);
 421   }
 422   // Light version of set_req() to init inputs after node creation.
 423   void init_req( uint i, Node *n ) {
 424     assert( i == 0 && this == n ||
 425             is_not_dead(n), "can not use dead node");
 426     assert( i < _cnt, "oob");
 427     assert( !VerifyHashTableKeys || _hash_lock == 0,
 428             "remove node from hash table before modifying it");
 429     assert( _in[i] == NULL, "sanity");
 430     _in[i] = n;
 431     if (n != NULL)      n->add_out((Node *)this);
 432     Compile::current()->record_modified_node(this);
 433   }
 434   // Find first occurrence of n among my edges:
 435   int find_edge(Node* n);
 436   int find_prec_edge(Node* n) {
 437     for (uint i = req(); i < len(); i++) {
 438       if (_in[i] == n) return i;
 439       if (_in[i] == NULL) {
 440         DEBUG_ONLY( while ((++i) < len()) assert(_in[i] == NULL, "Gap in prec edges!"); )
 441         break;
 442       }
 443     }
 444     return -1;
 445   }
 446   int replace_edge(Node* old, Node* neww);
 447   int replace_edges_in_range(Node* old, Node* neww, int start, int end);
 448   // NULL out all inputs to eliminate incoming Def-Use edges.
 449   // Return the number of edges between 'n' and 'this'
 450   int  disconnect_inputs(Node *n, Compile *c);
 451 
 452   // Quickly, return true if and only if I am Compile::current()->top().
 453   bool is_top() const {
 454     assert((this == (Node*) Compile::current()->top()) == (_out == NULL), "");
 455     return (_out == NULL);
 456   }
 457   // Reaffirm invariants for is_top.  (Only from Compile::set_cached_top_node.)
 458   void setup_is_top();
 459 
 460   // Strip away casting.  (It is depth-limited.)
 461   Node* uncast() const;
 462   // Return whether two Nodes are equivalent, after stripping casting.
 463   bool eqv_uncast(const Node* n) const {
 464     return (this->uncast() == n->uncast());
 465   }
 466 
 467   // Find out of current node that matches opcode.
 468   Node* find_out_with(int opcode);
 469   // Return true if the current node has an out that matches opcode.
 470   bool has_out_with(int opcode);
 471   // Return true if the current node has an out that matches any of the opcodes.
 472   bool has_out_with(int opcode1, int opcode2, int opcode3, int opcode4);
 473 
 474 private:
 475   static Node* uncast_helper(const Node* n);
 476 
 477   // Add an output edge to the end of the list
 478   void add_out( Node *n ) {
 479     if (is_top())  return;
 480     if( _outcnt == _outmax ) out_grow(_outcnt);
 481     _out[_outcnt++] = n;
 482   }
 483   // Delete an output edge
 484   void del_out( Node *n ) {
 485     if (is_top())  return;
 486     Node** outp = &_out[_outcnt];
 487     // Find and remove n
 488     do {
 489       assert(outp > _out, "Missing Def-Use edge");
 490     } while (*--outp != n);
 491     *outp = _out[--_outcnt];
 492     // Smash the old edge so it can't be used accidentally.
 493     debug_only(_out[_outcnt] = (Node *)(uintptr_t)0xdeadbeef);
 494     // Record that a change happened here.
 495     #if OPTO_DU_ITERATOR_ASSERT
 496     debug_only(_last_del = n; ++_del_tick);
 497     #endif
 498   }
 499   // Close gap after removing edge.
 500   void close_prec_gap_at(uint gap) {
 501     assert(_cnt <= gap && gap < _max, "no valid prec edge");
 502     uint i = gap;
 503     Node *last = NULL;
 504     for (; i < _max-1; ++i) {
 505       Node *next = _in[i+1];
 506       if (next == NULL) break;
 507       last = next;
 508     }
 509     _in[gap] = last; // Move last slot to empty one.
 510     _in[i] = NULL;   // NULL out last slot.
 511   }
 512 
 513 public:
 514   // Globally replace this node by a given new node, updating all uses.
 515   void replace_by(Node* new_node);
 516   // Globally replace this node by a given new node, updating all uses
 517   // and cutting input edges of old node.
 518   void subsume_by(Node* new_node, Compile* c) {
 519     replace_by(new_node);
 520     disconnect_inputs(NULL, c);
 521   }
 522   void set_req_X( uint i, Node *n, PhaseIterGVN *igvn );
 523   // Find the one non-null required input.  RegionNode only
 524   Node *nonnull_req() const;
 525   // Add or remove precedence edges
 526   void add_prec( Node *n );
 527   void rm_prec( uint i );
 528 
 529   // Note: prec(i) will not necessarily point to n if edge already exists.
 530   void set_prec( uint i, Node *n ) {
 531     assert(i < _max, "oob: i=%d, _max=%d", i, _max);
 532     assert(is_not_dead(n), "can not use dead node");
 533     assert(i >= _cnt, "not a precedence edge");
 534     // Avoid spec violation: duplicated prec edge.
 535     if (_in[i] == n) return;
 536     if (n == NULL || find_prec_edge(n) != -1) {
 537       rm_prec(i);
 538       return;
 539     }
 540     if (_in[i] != NULL) _in[i]->del_out((Node *)this);
 541     _in[i] = n;
 542     if (n != NULL) n->add_out((Node *)this);
 543   }
 544 
 545   // Set this node's index, used by cisc_version to replace current node
 546   void set_idx(uint new_idx) {
 547     const node_idx_t* ref = &_idx;
 548     *(node_idx_t*)ref = new_idx;
 549   }
 550   // Swap input edge order.  (Edge indexes i1 and i2 are usually 1 and 2.)
 551   void swap_edges(uint i1, uint i2) {
 552     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
 553     // Def-Use info is unchanged
 554     Node* n1 = in(i1);
 555     Node* n2 = in(i2);
 556     _in[i1] = n2;
 557     _in[i2] = n1;
 558     // If this node is in the hash table, make sure it doesn't need a rehash.
 559     assert(check_hash == NO_HASH || check_hash == hash(), "edge swap must preserve hash code");
 560   }
 561 
 562   // Iterators over input Nodes for a Node X are written as:
 563   // for( i = 0; i < X.req(); i++ ) ... X[i] ...
 564   // NOTE: Required edges can contain embedded NULL pointers.
 565 
 566 //----------------- Other Node Properties
 567 
 568   // Generate class IDs for (some) ideal nodes so that it is possible to determine
 569   // the type of a node using a non-virtual method call (the method is_<Node>() below).
 570   //
 571   // A class ID of an ideal node is a set of bits. In a class ID, a single bit determines
 572   // the type of the node the ID represents; another subset of an ID's bits are reserved
 573   // for the superclasses of the node represented by the ID.
 574   //
 575   // By design, if A is a supertype of B, A.is_B() returns true and B.is_A()
 576   // returns false. A.is_A() returns true.
 577   //
 578   // If two classes, A and B, have the same superclass, a different bit of A's class id
 579   // is reserved for A's type than for B's type. That bit is specified by the third
 580   // parameter in the macro DEFINE_CLASS_ID.
 581   //
 582   // By convention, classes with deeper hierarchy are declared first. Moreover,
 583   // classes with the same hierarchy depth are sorted by usage frequency.
 584   //
 585   // The query method masks the bits to cut off bits of subclasses and then compares
 586   // the result with the class id (see the macro DEFINE_CLASS_QUERY below).
 587   //
 588   //  Class_MachCall=30, ClassMask_MachCall=31
 589   // 12               8               4               0
 590   //  0   0   0   0   0   0   0   0   1   1   1   1   0
 591   //                                  |   |   |   |
 592   //                                  |   |   |   Bit_Mach=2
 593   //                                  |   |   Bit_MachReturn=4
 594   //                                  |   Bit_MachSafePoint=8
 595   //                                  Bit_MachCall=16
 596   //
 597   //  Class_CountedLoop=56, ClassMask_CountedLoop=63
 598   // 12               8               4               0
 599   //  0   0   0   0   0   0   0   1   1   1   0   0   0
 600   //                              |   |   |
 601   //                              |   |   Bit_Region=8
 602   //                              |   Bit_Loop=16
 603   //                              Bit_CountedLoop=32
 604 
 605   #define DEFINE_CLASS_ID(cl, supcl, subn) \
 606   Bit_##cl = (Class_##supcl == 0) ? 1 << subn : (Bit_##supcl) << (1 + subn) , \
 607   Class_##cl = Class_##supcl + Bit_##cl , \
 608   ClassMask_##cl = ((Bit_##cl << 1) - 1) ,
 609 
 610   // This enum is used only for C2 ideal and mach nodes with is_<node>() methods
 611   // so that it's values fits into 16 bits.
 612   enum NodeClasses {
 613     Bit_Node   = 0x0000,
 614     Class_Node = 0x0000,
 615     ClassMask_Node = 0xFFFF,
 616 
 617     DEFINE_CLASS_ID(Multi, Node, 0)
 618       DEFINE_CLASS_ID(SafePoint, Multi, 0)
 619         DEFINE_CLASS_ID(Call,      SafePoint, 0)
 620           DEFINE_CLASS_ID(CallJava,         Call, 0)
 621             DEFINE_CLASS_ID(CallStaticJava,   CallJava, 0)
 622             DEFINE_CLASS_ID(CallDynamicJava,  CallJava, 1)
 623           DEFINE_CLASS_ID(CallRuntime,      Call, 1)
 624             DEFINE_CLASS_ID(CallLeaf,         CallRuntime, 0)
 625           DEFINE_CLASS_ID(Allocate,         Call, 2)
 626             DEFINE_CLASS_ID(AllocateArray,    Allocate, 0)
 627           DEFINE_CLASS_ID(AbstractLock,     Call, 3)
 628             DEFINE_CLASS_ID(Lock,             AbstractLock, 0)
 629             DEFINE_CLASS_ID(Unlock,           AbstractLock, 1)
 630           DEFINE_CLASS_ID(ArrayCopy,        Call, 4)
 631       DEFINE_CLASS_ID(MultiBranch, Multi, 1)
 632         DEFINE_CLASS_ID(PCTable,     MultiBranch, 0)
 633           DEFINE_CLASS_ID(Catch,       PCTable, 0)
 634           DEFINE_CLASS_ID(Jump,        PCTable, 1)
 635         DEFINE_CLASS_ID(If,          MultiBranch, 1)
 636           DEFINE_CLASS_ID(CountedLoopEnd,         If, 0)
 637           DEFINE_CLASS_ID(RangeCheck,             If, 1)
 638           DEFINE_CLASS_ID(OuterStripMinedLoopEnd, If, 2)
 639         DEFINE_CLASS_ID(NeverBranch, MultiBranch, 2)
 640       DEFINE_CLASS_ID(Start,       Multi, 2)
 641       DEFINE_CLASS_ID(MemBar,      Multi, 3)
 642         DEFINE_CLASS_ID(Initialize,       MemBar, 0)
 643         DEFINE_CLASS_ID(MemBarStoreStore, MemBar, 1)
 644       DEFINE_CLASS_ID(LoadBarrier, Multi, 4)
 645 
 646     DEFINE_CLASS_ID(Mach,  Node, 1)
 647       DEFINE_CLASS_ID(MachReturn, Mach, 0)
 648         DEFINE_CLASS_ID(MachSafePoint, MachReturn, 0)
 649           DEFINE_CLASS_ID(MachCall, MachSafePoint, 0)
 650             DEFINE_CLASS_ID(MachCallJava,         MachCall, 0)
 651               DEFINE_CLASS_ID(MachCallStaticJava,   MachCallJava, 0)
 652               DEFINE_CLASS_ID(MachCallDynamicJava,  MachCallJava, 1)
 653             DEFINE_CLASS_ID(MachCallRuntime,      MachCall, 1)
 654               DEFINE_CLASS_ID(MachCallLeaf,         MachCallRuntime, 0)
 655       DEFINE_CLASS_ID(MachBranch, Mach, 1)
 656         DEFINE_CLASS_ID(MachIf,         MachBranch, 0)
 657         DEFINE_CLASS_ID(MachGoto,       MachBranch, 1)
 658         DEFINE_CLASS_ID(MachNullCheck,  MachBranch, 2)
 659       DEFINE_CLASS_ID(MachSpillCopy,    Mach, 2)
 660       DEFINE_CLASS_ID(MachTemp,         Mach, 3)
 661       DEFINE_CLASS_ID(MachConstantBase, Mach, 4)
 662       DEFINE_CLASS_ID(MachConstant,     Mach, 5)
 663         DEFINE_CLASS_ID(MachJump,       MachConstant, 0)
 664       DEFINE_CLASS_ID(MachMerge,        Mach, 6)
 665       DEFINE_CLASS_ID(MachMemBar,       Mach, 7)
 666 
 667     DEFINE_CLASS_ID(Type,  Node, 2)
 668       DEFINE_CLASS_ID(Phi,   Type, 0)
 669       DEFINE_CLASS_ID(ConstraintCast, Type, 1)
 670         DEFINE_CLASS_ID(CastII, ConstraintCast, 0)
 671         DEFINE_CLASS_ID(CastLL, ConstraintCast, 1)
 672         DEFINE_CLASS_ID(CheckCastPP, ConstraintCast, 2)
 673       DEFINE_CLASS_ID(CMove, Type, 3)
 674       DEFINE_CLASS_ID(SafePointScalarObject, Type, 4)
 675       DEFINE_CLASS_ID(DecodeNarrowPtr, Type, 5)
 676         DEFINE_CLASS_ID(DecodeN, DecodeNarrowPtr, 0)
 677         DEFINE_CLASS_ID(DecodeNKlass, DecodeNarrowPtr, 1)
 678       DEFINE_CLASS_ID(EncodeNarrowPtr, Type, 6)
 679         DEFINE_CLASS_ID(EncodeP, EncodeNarrowPtr, 0)
 680         DEFINE_CLASS_ID(EncodePKlass, EncodeNarrowPtr, 1)
 681 
 682     DEFINE_CLASS_ID(Proj,  Node, 3)
 683       DEFINE_CLASS_ID(CatchProj, Proj, 0)
 684       DEFINE_CLASS_ID(JumpProj,  Proj, 1)
 685       DEFINE_CLASS_ID(IfProj,    Proj, 2)
 686         DEFINE_CLASS_ID(IfTrue,    IfProj, 0)
 687         DEFINE_CLASS_ID(IfFalse,   IfProj, 1)
 688       DEFINE_CLASS_ID(Parm,      Proj, 4)
 689       DEFINE_CLASS_ID(MachProj,  Proj, 5)
 690 
 691     DEFINE_CLASS_ID(Mem,   Node, 4)
 692       DEFINE_CLASS_ID(Load,  Mem, 0)
 693         DEFINE_CLASS_ID(LoadVector,  Load, 0)
 694           DEFINE_CLASS_ID(LoadBarrierSlowReg, Load, 1)
 695           DEFINE_CLASS_ID(LoadBarrierWeakSlowReg, Load, 2)
 696       DEFINE_CLASS_ID(Store, Mem, 1)
 697         DEFINE_CLASS_ID(StoreVector, Store, 0)
 698       DEFINE_CLASS_ID(LoadStore, Mem, 2)
 699         DEFINE_CLASS_ID(LoadStoreConditional, LoadStore, 0)
 700           DEFINE_CLASS_ID(CompareAndSwap, LoadStoreConditional, 0)
 701         DEFINE_CLASS_ID(CompareAndExchangeNode, LoadStore, 1)
 702 
 703     DEFINE_CLASS_ID(Region, Node, 5)
 704       DEFINE_CLASS_ID(Loop, Region, 0)
 705         DEFINE_CLASS_ID(Root,                Loop, 0)
 706         DEFINE_CLASS_ID(CountedLoop,         Loop, 1)
 707         DEFINE_CLASS_ID(OuterStripMinedLoop, Loop, 2)
 708 
 709     DEFINE_CLASS_ID(Sub,   Node, 6)
 710       DEFINE_CLASS_ID(Cmp,   Sub, 0)
 711         DEFINE_CLASS_ID(FastLock,   Cmp, 0)
 712         DEFINE_CLASS_ID(FastUnlock, Cmp, 1)
 713 
 714     DEFINE_CLASS_ID(MergeMem, Node, 7)
 715     DEFINE_CLASS_ID(Bool,     Node, 8)
 716     DEFINE_CLASS_ID(AddP,     Node, 9)
 717     DEFINE_CLASS_ID(BoxLock,  Node, 10)
 718     DEFINE_CLASS_ID(Add,      Node, 11)
 719     DEFINE_CLASS_ID(Mul,      Node, 12)
 720     DEFINE_CLASS_ID(Vector,   Node, 13)
 721     DEFINE_CLASS_ID(ClearArray, Node, 14)
 722 
 723     _max_classes  = ClassMask_ClearArray
 724   };
 725   #undef DEFINE_CLASS_ID
 726 
 727   // Flags are sorted by usage frequency.
 728   enum NodeFlags {
 729     Flag_is_Copy                     = 0x01, // should be first bit to avoid shift
 730     Flag_rematerialize               = Flag_is_Copy << 1,
 731     Flag_needs_anti_dependence_check = Flag_rematerialize << 1,
 732     Flag_is_macro                    = Flag_needs_anti_dependence_check << 1,
 733     Flag_is_Con                      = Flag_is_macro << 1,
 734     Flag_is_cisc_alternate           = Flag_is_Con << 1,
 735     Flag_is_dead_loop_safe           = Flag_is_cisc_alternate << 1,
 736     Flag_may_be_short_branch         = Flag_is_dead_loop_safe << 1,
 737     Flag_avoid_back_to_back_before   = Flag_may_be_short_branch << 1,
 738     Flag_avoid_back_to_back_after    = Flag_avoid_back_to_back_before << 1,
 739     Flag_has_call                    = Flag_avoid_back_to_back_after << 1,
 740     Flag_is_reduction                = Flag_has_call << 1,
 741     Flag_is_scheduled                = Flag_is_reduction << 1,
 742     Flag_has_vector_mask_set         = Flag_is_scheduled << 1,
 743     Flag_is_expensive                = Flag_has_vector_mask_set << 1,
 744     _max_flags = (Flag_is_expensive << 1) - 1 // allow flags combination
 745   };
 746 
 747 private:
 748   jushort _class_id;
 749   jushort _flags;
 750 
 751 protected:
 752   // These methods should be called from constructors only.
 753   void init_class_id(jushort c) {
 754     assert(c <= _max_classes, "invalid node class");
 755     _class_id = c; // cast out const
 756   }
 757   void init_flags(jushort fl) {
 758     assert(fl <= _max_flags, "invalid node flag");
 759     _flags |= fl;
 760   }
 761   void clear_flag(jushort fl) {
 762     assert(fl <= _max_flags, "invalid node flag");
 763     _flags &= ~fl;
 764   }
 765 
 766 public:
 767   const jushort class_id() const { return _class_id; }
 768 
 769   const jushort flags() const { return _flags; }
 770 
 771   void add_flag(jushort fl) { init_flags(fl); }
 772 
 773   void remove_flag(jushort fl) { clear_flag(fl); }
 774 
 775   // Return a dense integer opcode number
 776   virtual int Opcode() const;
 777 
 778   // Virtual inherited Node size
 779   virtual uint size_of() const;
 780 
 781   // Other interesting Node properties
 782   #define DEFINE_CLASS_QUERY(type)                           \
 783   bool is_##type() const {                                   \
 784     return ((_class_id & ClassMask_##type) == Class_##type); \
 785   }                                                          \
 786   type##Node *as_##type() const {                            \
 787     assert(is_##type(), "invalid node class");               \
 788     return (type##Node*)this;                                \
 789   }                                                          \
 790   type##Node* isa_##type() const {                           \
 791     return (is_##type()) ? as_##type() : NULL;               \
 792   }
 793 
 794   DEFINE_CLASS_QUERY(AbstractLock)
 795   DEFINE_CLASS_QUERY(Add)
 796   DEFINE_CLASS_QUERY(AddP)
 797   DEFINE_CLASS_QUERY(Allocate)
 798   DEFINE_CLASS_QUERY(AllocateArray)
 799   DEFINE_CLASS_QUERY(ArrayCopy)
 800   DEFINE_CLASS_QUERY(Bool)
 801   DEFINE_CLASS_QUERY(BoxLock)
 802   DEFINE_CLASS_QUERY(Call)
 803   DEFINE_CLASS_QUERY(CallDynamicJava)
 804   DEFINE_CLASS_QUERY(CallJava)
 805   DEFINE_CLASS_QUERY(CallLeaf)
 806   DEFINE_CLASS_QUERY(CallRuntime)
 807   DEFINE_CLASS_QUERY(CallStaticJava)
 808   DEFINE_CLASS_QUERY(Catch)
 809   DEFINE_CLASS_QUERY(CatchProj)
 810   DEFINE_CLASS_QUERY(CheckCastPP)
 811   DEFINE_CLASS_QUERY(CastII)
 812   DEFINE_CLASS_QUERY(CastLL)
 813   DEFINE_CLASS_QUERY(ConstraintCast)
 814   DEFINE_CLASS_QUERY(ClearArray)
 815   DEFINE_CLASS_QUERY(CMove)
 816   DEFINE_CLASS_QUERY(Cmp)
 817   DEFINE_CLASS_QUERY(CountedLoop)
 818   DEFINE_CLASS_QUERY(CountedLoopEnd)
 819   DEFINE_CLASS_QUERY(DecodeNarrowPtr)
 820   DEFINE_CLASS_QUERY(DecodeN)
 821   DEFINE_CLASS_QUERY(DecodeNKlass)
 822   DEFINE_CLASS_QUERY(EncodeNarrowPtr)
 823   DEFINE_CLASS_QUERY(EncodeP)
 824   DEFINE_CLASS_QUERY(EncodePKlass)
 825   DEFINE_CLASS_QUERY(FastLock)
 826   DEFINE_CLASS_QUERY(FastUnlock)
 827   DEFINE_CLASS_QUERY(If)
 828   DEFINE_CLASS_QUERY(RangeCheck)
 829   DEFINE_CLASS_QUERY(IfProj)
 830   DEFINE_CLASS_QUERY(IfFalse)
 831   DEFINE_CLASS_QUERY(IfTrue)
 832   DEFINE_CLASS_QUERY(Initialize)
 833   DEFINE_CLASS_QUERY(Jump)
 834   DEFINE_CLASS_QUERY(JumpProj)
 835   DEFINE_CLASS_QUERY(Load)
 836   DEFINE_CLASS_QUERY(LoadStore)
 837   DEFINE_CLASS_QUERY(LoadBarrier)
 838   DEFINE_CLASS_QUERY(LoadBarrierSlowReg)
 839   DEFINE_CLASS_QUERY(LoadBarrierWeakSlowReg)
 840   DEFINE_CLASS_QUERY(Lock)
 841   DEFINE_CLASS_QUERY(Loop)
 842   DEFINE_CLASS_QUERY(Mach)
 843   DEFINE_CLASS_QUERY(MachBranch)
 844   DEFINE_CLASS_QUERY(MachCall)
 845   DEFINE_CLASS_QUERY(MachCallDynamicJava)
 846   DEFINE_CLASS_QUERY(MachCallJava)
 847   DEFINE_CLASS_QUERY(MachCallLeaf)
 848   DEFINE_CLASS_QUERY(MachCallRuntime)
 849   DEFINE_CLASS_QUERY(MachCallStaticJava)
 850   DEFINE_CLASS_QUERY(MachConstantBase)
 851   DEFINE_CLASS_QUERY(MachConstant)
 852   DEFINE_CLASS_QUERY(MachGoto)
 853   DEFINE_CLASS_QUERY(MachIf)
 854   DEFINE_CLASS_QUERY(MachJump)
 855   DEFINE_CLASS_QUERY(MachNullCheck)
 856   DEFINE_CLASS_QUERY(MachProj)
 857   DEFINE_CLASS_QUERY(MachReturn)
 858   DEFINE_CLASS_QUERY(MachSafePoint)
 859   DEFINE_CLASS_QUERY(MachSpillCopy)
 860   DEFINE_CLASS_QUERY(MachTemp)
 861   DEFINE_CLASS_QUERY(MachMemBar)
 862   DEFINE_CLASS_QUERY(MachMerge)
 863   DEFINE_CLASS_QUERY(Mem)
 864   DEFINE_CLASS_QUERY(MemBar)
 865   DEFINE_CLASS_QUERY(MemBarStoreStore)
 866   DEFINE_CLASS_QUERY(MergeMem)
 867   DEFINE_CLASS_QUERY(Mul)
 868   DEFINE_CLASS_QUERY(Multi)
 869   DEFINE_CLASS_QUERY(MultiBranch)
 870   DEFINE_CLASS_QUERY(OuterStripMinedLoop)
 871   DEFINE_CLASS_QUERY(OuterStripMinedLoopEnd)
 872   DEFINE_CLASS_QUERY(Parm)
 873   DEFINE_CLASS_QUERY(PCTable)
 874   DEFINE_CLASS_QUERY(Phi)
 875   DEFINE_CLASS_QUERY(Proj)
 876   DEFINE_CLASS_QUERY(Region)
 877   DEFINE_CLASS_QUERY(Root)
 878   DEFINE_CLASS_QUERY(SafePoint)
 879   DEFINE_CLASS_QUERY(SafePointScalarObject)
 880   DEFINE_CLASS_QUERY(Start)
 881   DEFINE_CLASS_QUERY(Store)
 882   DEFINE_CLASS_QUERY(Sub)
 883   DEFINE_CLASS_QUERY(Type)
 884   DEFINE_CLASS_QUERY(Vector)
 885   DEFINE_CLASS_QUERY(LoadVector)
 886   DEFINE_CLASS_QUERY(StoreVector)
 887   DEFINE_CLASS_QUERY(Unlock)
 888 
 889   #undef DEFINE_CLASS_QUERY
 890 
 891   // duplicate of is_MachSpillCopy()
 892   bool is_SpillCopy () const {
 893     return ((_class_id & ClassMask_MachSpillCopy) == Class_MachSpillCopy);
 894   }
 895 
 896   bool is_Con () const { return (_flags & Flag_is_Con) != 0; }
 897   // The data node which is safe to leave in dead loop during IGVN optimization.
 898   bool is_dead_loop_safe() const {
 899     return is_Phi() || (is_Proj() && in(0) == NULL) ||
 900            ((_flags & (Flag_is_dead_loop_safe | Flag_is_Con)) != 0 &&
 901             (!is_Proj() || !in(0)->is_Allocate()));
 902   }
 903 
 904   // is_Copy() returns copied edge index (0 or 1)
 905   uint is_Copy() const { return (_flags & Flag_is_Copy); }
 906 
 907   virtual bool is_CFG() const { return false; }
 908 
 909   // If this node is control-dependent on a test, can it be
 910   // rerouted to a dominating equivalent test?  This is usually
 911   // true of non-CFG nodes, but can be false for operations which
 912   // depend for their correct sequencing on more than one test.
 913   // (In that case, hoisting to a dominating test may silently
 914   // skip some other important test.)
 915   virtual bool depends_only_on_test() const { assert(!is_CFG(), ""); return true; };
 916 
 917   // When building basic blocks, I need to have a notion of block beginning
 918   // Nodes, next block selector Nodes (block enders), and next block
 919   // projections.  These calls need to work on their machine equivalents.  The
 920   // Ideal beginning Nodes are RootNode, RegionNode and StartNode.
 921   bool is_block_start() const {
 922     if ( is_Region() )
 923       return this == (const Node*)in(0);
 924     else
 925       return is_Start();
 926   }
 927 
 928   // The Ideal control projection Nodes are IfTrue/IfFalse, JumpProjNode, Root,
 929   // Goto and Return.  This call also returns the block ending Node.
 930   virtual const Node *is_block_proj() const;
 931 
 932   // The node is a "macro" node which needs to be expanded before matching
 933   bool is_macro() const { return (_flags & Flag_is_macro) != 0; }
 934   // The node is expensive: the best control is set during loop opts
 935   bool is_expensive() const { return (_flags & Flag_is_expensive) != 0 && in(0) != NULL; }
 936 
 937   // An arithmetic node which accumulates a data in a loop.
 938   // It must have the loop's phi as input and provide a def to the phi.
 939   bool is_reduction() const { return (_flags & Flag_is_reduction) != 0; }
 940 
 941   // The node is a CountedLoopEnd with a mask annotation so as to emit a restore context
 942   bool has_vector_mask_set() const { return (_flags & Flag_has_vector_mask_set) != 0; }
 943 
 944   // Used in lcm to mark nodes that have scheduled
 945   bool is_scheduled() const { return (_flags & Flag_is_scheduled) != 0; }
 946 
 947 //----------------- Optimization
 948 
 949   // Get the worst-case Type output for this Node.
 950   virtual const class Type *bottom_type() const;
 951 
 952   // If we find a better type for a node, try to record it permanently.
 953   // Return true if this node actually changed.
 954   // Be sure to do the hash_delete game in the "rehash" variant.
 955   void raise_bottom_type(const Type* new_type);
 956 
 957   // Get the address type with which this node uses and/or defs memory,
 958   // or NULL if none.  The address type is conservatively wide.
 959   // Returns non-null for calls, membars, loads, stores, etc.
 960   // Returns TypePtr::BOTTOM if the node touches memory "broadly".
 961   virtual const class TypePtr *adr_type() const { return NULL; }
 962 
 963   // Return an existing node which computes the same function as this node.
 964   // The optimistic combined algorithm requires this to return a Node which
 965   // is a small number of steps away (e.g., one of my inputs).
 966   virtual Node* Identity(PhaseGVN* phase);
 967 
 968   // Return the set of values this Node can take on at runtime.
 969   virtual const Type* Value(PhaseGVN* phase) const;
 970 
 971   // Return a node which is more "ideal" than the current node.
 972   // The invariants on this call are subtle.  If in doubt, read the
 973   // treatise in node.cpp above the default implemention AND TEST WITH
 974   // +VerifyIterativeGVN!
 975   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 976 
 977   // Some nodes have specific Ideal subgraph transformations only if they are
 978   // unique users of specific nodes. Such nodes should be put on IGVN worklist
 979   // for the transformations to happen.
 980   bool has_special_unique_user() const;
 981 
 982   // Skip Proj and CatchProj nodes chains. Check for Null and Top.
 983   Node* find_exact_control(Node* ctrl);
 984 
 985   // Check if 'this' node dominates or equal to 'sub'.
 986   bool dominates(Node* sub, Node_List &nlist);
 987 
 988 protected:
 989   bool remove_dead_region(PhaseGVN *phase, bool can_reshape);
 990 public:
 991 
 992   // See if there is valid pipeline info
 993   static  const Pipeline *pipeline_class();
 994   virtual const Pipeline *pipeline() const;
 995 
 996   // Compute the latency from the def to this instruction of the ith input node
 997   uint latency(uint i);
 998 
 999   // Hash & compare functions, for pessimistic value numbering
1000 
1001   // If the hash function returns the special sentinel value NO_HASH,
1002   // the node is guaranteed never to compare equal to any other node.
1003   // If we accidentally generate a hash with value NO_HASH the node
1004   // won't go into the table and we'll lose a little optimization.
1005   enum { NO_HASH = 0 };
1006   virtual uint hash() const;
1007   virtual uint cmp( const Node &n ) const;
1008 
1009   // Operation appears to be iteratively computed (such as an induction variable)
1010   // It is possible for this operation to return false for a loop-varying
1011   // value, if it appears (by local graph inspection) to be computed by a simple conditional.
1012   bool is_iteratively_computed();
1013 
1014   // Determine if a node is Counted loop induction variable.
1015   // The method is defined in loopnode.cpp.
1016   const Node* is_loop_iv() const;
1017 
1018   // Return a node with opcode "opc" and same inputs as "this" if one can
1019   // be found; Otherwise return NULL;
1020   Node* find_similar(int opc);
1021 
1022   // Return the unique control out if only one. Null if none or more than one.
1023   Node* unique_ctrl_out() const;
1024 
1025   // Set control or add control as precedence edge
1026   void ensure_control_or_add_prec(Node* c);
1027 
1028 //----------------- Code Generation
1029 
1030   // Ideal register class for Matching.  Zero means unmatched instruction
1031   // (these are cloned instead of converted to machine nodes).
1032   virtual uint ideal_reg() const;
1033 
1034   static const uint NotAMachineReg;   // must be > max. machine register
1035 
1036   // Do we Match on this edge index or not?  Generally false for Control
1037   // and true for everything else.  Weird for calls & returns.
1038   virtual uint match_edge(uint idx) const;
1039 
1040   // Register class output is returned in
1041   virtual const RegMask &out_RegMask() const;
1042   // Register class input is expected in
1043   virtual const RegMask &in_RegMask(uint) const;
1044   // Should we clone rather than spill this instruction?
1045   bool rematerialize() const;
1046 
1047   // Return JVM State Object if this Node carries debug info, or NULL otherwise
1048   virtual JVMState* jvms() const;
1049 
1050   // Print as assembly
1051   virtual void format( PhaseRegAlloc *, outputStream* st = tty ) const;
1052   // Emit bytes starting at parameter 'ptr'
1053   // Bump 'ptr' by the number of output bytes
1054   virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const;
1055   // Size of instruction in bytes
1056   virtual uint size(PhaseRegAlloc *ra_) const;
1057 
1058   // Convenience function to extract an integer constant from a node.
1059   // If it is not an integer constant (either Con, CastII, or Mach),
1060   // return value_if_unknown.
1061   jint find_int_con(jint value_if_unknown) const {
1062     const TypeInt* t = find_int_type();
1063     return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
1064   }
1065   // Return the constant, knowing it is an integer constant already
1066   jint get_int() const {
1067     const TypeInt* t = find_int_type();
1068     guarantee(t != NULL, "must be con");
1069     return t->get_con();
1070   }
1071   // Here's where the work is done.  Can produce non-constant int types too.
1072   const TypeInt* find_int_type() const;
1073 
1074   // Same thing for long (and intptr_t, via type.hpp):
1075   jlong get_long() const {
1076     const TypeLong* t = find_long_type();
1077     guarantee(t != NULL, "must be con");
1078     return t->get_con();
1079   }
1080   jlong find_long_con(jint value_if_unknown) const {
1081     const TypeLong* t = find_long_type();
1082     return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
1083   }
1084   const TypeLong* find_long_type() const;
1085 
1086   const TypePtr* get_ptr_type() const;
1087 
1088   // These guys are called by code generated by ADLC:
1089   intptr_t get_ptr() const;
1090   intptr_t get_narrowcon() const;
1091   jdouble getd() const;
1092   jfloat getf() const;
1093 
1094   // Nodes which are pinned into basic blocks
1095   virtual bool pinned() const { return false; }
1096 
1097   // Nodes which use memory without consuming it, hence need antidependences
1098   // More specifically, needs_anti_dependence_check returns true iff the node
1099   // (a) does a load, and (b) does not perform a store (except perhaps to a
1100   // stack slot or some other unaliased location).
1101   bool needs_anti_dependence_check() const;
1102 
1103   // Return which operand this instruction may cisc-spill. In other words,
1104   // return operand position that can convert from reg to memory access
1105   virtual int cisc_operand() const { return AdlcVMDeps::Not_cisc_spillable; }
1106   bool is_cisc_alternate() const { return (_flags & Flag_is_cisc_alternate) != 0; }
1107 
1108 //----------------- Graph walking
1109 public:
1110   // Walk and apply member functions recursively.
1111   // Supplied (this) pointer is root.
1112   void walk(NFunc pre, NFunc post, void *env);
1113   static void nop(Node &, void*); // Dummy empty function
1114   static void packregion( Node &n, void* );
1115 private:
1116   void walk_(NFunc pre, NFunc post, void *env, VectorSet &visited);
1117 
1118 //----------------- Printing, etc
1119 public:
1120 #ifndef PRODUCT
1121   Node* find(int idx) const;         // Search the graph for the given idx.
1122   Node* find_ctrl(int idx) const;    // Search control ancestors for the given idx.
1123   void dump() const { dump("\n"); }  // Print this node.
1124   void dump(const char* suffix, bool mark = false, outputStream *st = tty) const; // Print this node.
1125   void dump(int depth) const;        // Print this node, recursively to depth d
1126   void dump_ctrl(int depth) const;   // Print control nodes, to depth d
1127   void dump_comp() const;            // Print this node in compact representation.
1128   // Print this node in compact representation.
1129   void dump_comp(const char* suffix, outputStream *st = tty) const;
1130   virtual void dump_req(outputStream *st = tty) const;    // Print required-edge info
1131   virtual void dump_prec(outputStream *st = tty) const;   // Print precedence-edge info
1132   virtual void dump_out(outputStream *st = tty) const;    // Print the output edge info
1133   virtual void dump_spec(outputStream *st) const {};      // Print per-node info
1134   // Print compact per-node info
1135   virtual void dump_compact_spec(outputStream *st) const { dump_spec(st); }
1136   void dump_related() const;             // Print related nodes (depends on node at hand).
1137   // Print related nodes up to given depths for input and output nodes.
1138   void dump_related(uint d_in, uint d_out) const;
1139   void dump_related_compact() const;     // Print related nodes in compact representation.
1140   // Collect related nodes.
1141   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
1142   // Collect nodes starting from this node, explicitly including/excluding control and data links.
1143   void collect_nodes(GrowableArray<Node*> *ns, int d, bool ctrl, bool data) const;
1144 
1145   // Node collectors, to be used in implementations of Node::rel().
1146   // Collect the entire data input graph. Include control inputs if requested.
1147   void collect_nodes_in_all_data(GrowableArray<Node*> *ns, bool ctrl) const;
1148   // Collect the entire control input graph. Include data inputs if requested.
1149   void collect_nodes_in_all_ctrl(GrowableArray<Node*> *ns, bool data) const;
1150   // Collect the entire output graph until hitting and including control nodes.
1151   void collect_nodes_out_all_ctrl_boundary(GrowableArray<Node*> *ns) const;
1152 
1153   void verify_edges(Unique_Node_List &visited); // Verify bi-directional edges
1154   void verify() const;               // Check Def-Use info for my subgraph
1155   static void verify_recur(const Node *n, int verify_depth, VectorSet &old_space, VectorSet &new_space);
1156 
1157   // This call defines a class-unique string used to identify class instances
1158   virtual const char *Name() const;
1159 
1160   void dump_format(PhaseRegAlloc *ra) const; // debug access to MachNode::format(...)
1161   // RegMask Print Functions
1162   void dump_in_regmask(int idx) { in_RegMask(idx).dump(); }
1163   void dump_out_regmask() { out_RegMask().dump(); }
1164   static bool in_dump() { return Compile::current()->_in_dump_cnt > 0; }
1165   void fast_dump() const {
1166     tty->print("%4d: %-17s", _idx, Name());
1167     for (uint i = 0; i < len(); i++)
1168       if (in(i))
1169         tty->print(" %4d", in(i)->_idx);
1170       else
1171         tty->print(" NULL");
1172     tty->print("\n");
1173   }
1174 #endif
1175 #ifdef ASSERT
1176   void verify_construction();
1177   bool verify_jvms(const JVMState* jvms) const;
1178   int  _debug_idx;                     // Unique value assigned to every node.
1179   int   debug_idx() const              { return _debug_idx; }
1180   void  set_debug_idx( int debug_idx ) { _debug_idx = debug_idx; }
1181 
1182   Node* _debug_orig;                   // Original version of this, if any.
1183   Node*  debug_orig() const            { return _debug_orig; }
1184   void   set_debug_orig(Node* orig);   // _debug_orig = orig
1185 
1186   int        _hash_lock;               // Barrier to modifications of nodes in the hash table
1187   void  enter_hash_lock() { ++_hash_lock; assert(_hash_lock < 99, "in too many hash tables?"); }
1188   void   exit_hash_lock() { --_hash_lock; assert(_hash_lock >= 0, "mispaired hash locks"); }
1189 
1190   static void init_NodeProperty();
1191 
1192   #if OPTO_DU_ITERATOR_ASSERT
1193   const Node* _last_del;               // The last deleted node.
1194   uint        _del_tick;               // Bumped when a deletion happens..
1195   #endif
1196 #endif
1197 };
1198 
1199 
1200 #ifndef PRODUCT
1201 
1202 // Used in debugging code to avoid walking across dead or uninitialized edges.
1203 inline bool NotANode(const Node* n) {
1204   if (n == NULL)                   return true;
1205   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
1206   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
1207   return false;
1208 }
1209 
1210 #endif
1211 
1212 
1213 //-----------------------------------------------------------------------------
1214 // Iterators over DU info, and associated Node functions.
1215 
1216 #if OPTO_DU_ITERATOR_ASSERT
1217 
1218 // Common code for assertion checking on DU iterators.
1219 class DUIterator_Common {
1220 #ifdef ASSERT
1221  protected:
1222   bool         _vdui;               // cached value of VerifyDUIterators
1223   const Node*  _node;               // the node containing the _out array
1224   uint         _outcnt;             // cached node->_outcnt
1225   uint         _del_tick;           // cached node->_del_tick
1226   Node*        _last;               // last value produced by the iterator
1227 
1228   void sample(const Node* node);    // used by c'tor to set up for verifies
1229   void verify(const Node* node, bool at_end_ok = false);
1230   void verify_resync();
1231   void reset(const DUIterator_Common& that);
1232 
1233 // The VDUI_ONLY macro protects code conditionalized on VerifyDUIterators
1234   #define I_VDUI_ONLY(i,x) { if ((i)._vdui) { x; } }
1235 #else
1236   #define I_VDUI_ONLY(i,x) { }
1237 #endif //ASSERT
1238 };
1239 
1240 #define VDUI_ONLY(x)     I_VDUI_ONLY(*this, x)
1241 
1242 // Default DU iterator.  Allows appends onto the out array.
1243 // Allows deletion from the out array only at the current point.
1244 // Usage:
1245 //  for (DUIterator i = x->outs(); x->has_out(i); i++) {
1246 //    Node* y = x->out(i);
1247 //    ...
1248 //  }
1249 // Compiles in product mode to a unsigned integer index, which indexes
1250 // onto a repeatedly reloaded base pointer of x->_out.  The loop predicate
1251 // also reloads x->_outcnt.  If you delete, you must perform "--i" just
1252 // before continuing the loop.  You must delete only the last-produced
1253 // edge.  You must delete only a single copy of the last-produced edge,
1254 // or else you must delete all copies at once (the first time the edge
1255 // is produced by the iterator).
1256 class DUIterator : public DUIterator_Common {
1257   friend class Node;
1258 
1259   // This is the index which provides the product-mode behavior.
1260   // Whatever the product-mode version of the system does to the
1261   // DUI index is done to this index.  All other fields in
1262   // this class are used only for assertion checking.
1263   uint         _idx;
1264 
1265   #ifdef ASSERT
1266   uint         _refresh_tick;    // Records the refresh activity.
1267 
1268   void sample(const Node* node); // Initialize _refresh_tick etc.
1269   void verify(const Node* node, bool at_end_ok = false);
1270   void verify_increment();       // Verify an increment operation.
1271   void verify_resync();          // Verify that we can back up over a deletion.
1272   void verify_finish();          // Verify that the loop terminated properly.
1273   void refresh();                // Resample verification info.
1274   void reset(const DUIterator& that);  // Resample after assignment.
1275   #endif
1276 
1277   DUIterator(const Node* node, int dummy_to_avoid_conversion)
1278     { _idx = 0;                         debug_only(sample(node)); }
1279 
1280  public:
1281   // initialize to garbage; clear _vdui to disable asserts
1282   DUIterator()
1283     { /*initialize to garbage*/         debug_only(_vdui = false); }
1284 
1285   void operator++(int dummy_to_specify_postfix_op)
1286     { _idx++;                           VDUI_ONLY(verify_increment()); }
1287 
1288   void operator--()
1289     { VDUI_ONLY(verify_resync());       --_idx; }
1290 
1291   ~DUIterator()
1292     { VDUI_ONLY(verify_finish()); }
1293 
1294   void operator=(const DUIterator& that)
1295     { _idx = that._idx;                 debug_only(reset(that)); }
1296 };
1297 
1298 DUIterator Node::outs() const
1299   { return DUIterator(this, 0); }
1300 DUIterator& Node::refresh_out_pos(DUIterator& i) const
1301   { I_VDUI_ONLY(i, i.refresh());        return i; }
1302 bool Node::has_out(DUIterator& i) const
1303   { I_VDUI_ONLY(i, i.verify(this,true));return i._idx < _outcnt; }
1304 Node*    Node::out(DUIterator& i) const
1305   { I_VDUI_ONLY(i, i.verify(this));     return debug_only(i._last=) _out[i._idx]; }
1306 
1307 
1308 // Faster DU iterator.  Disallows insertions into the out array.
1309 // Allows deletion from the out array only at the current point.
1310 // Usage:
1311 //  for (DUIterator_Fast imax, i = x->fast_outs(imax); i < imax; i++) {
1312 //    Node* y = x->fast_out(i);
1313 //    ...
1314 //  }
1315 // Compiles in product mode to raw Node** pointer arithmetic, with
1316 // no reloading of pointers from the original node x.  If you delete,
1317 // you must perform "--i; --imax" just before continuing the loop.
1318 // If you delete multiple copies of the same edge, you must decrement
1319 // imax, but not i, multiple times:  "--i, imax -= num_edges".
1320 class DUIterator_Fast : public DUIterator_Common {
1321   friend class Node;
1322   friend class DUIterator_Last;
1323 
1324   // This is the pointer which provides the product-mode behavior.
1325   // Whatever the product-mode version of the system does to the
1326   // DUI pointer is done to this pointer.  All other fields in
1327   // this class are used only for assertion checking.
1328   Node**       _outp;
1329 
1330   #ifdef ASSERT
1331   void verify(const Node* node, bool at_end_ok = false);
1332   void verify_limit();
1333   void verify_resync();
1334   void verify_relimit(uint n);
1335   void reset(const DUIterator_Fast& that);
1336   #endif
1337 
1338   // Note:  offset must be signed, since -1 is sometimes passed
1339   DUIterator_Fast(const Node* node, ptrdiff_t offset)
1340     { _outp = node->_out + offset;      debug_only(sample(node)); }
1341 
1342  public:
1343   // initialize to garbage; clear _vdui to disable asserts
1344   DUIterator_Fast()
1345     { /*initialize to garbage*/         debug_only(_vdui = false); }
1346 
1347   void operator++(int dummy_to_specify_postfix_op)
1348     { _outp++;                          VDUI_ONLY(verify(_node, true)); }
1349 
1350   void operator--()
1351     { VDUI_ONLY(verify_resync());       --_outp; }
1352 
1353   void operator-=(uint n)   // applied to the limit only
1354     { _outp -= n;           VDUI_ONLY(verify_relimit(n));  }
1355 
1356   bool operator<(DUIterator_Fast& limit) {
1357     I_VDUI_ONLY(*this, this->verify(_node, true));
1358     I_VDUI_ONLY(limit, limit.verify_limit());
1359     return _outp < limit._outp;
1360   }
1361 
1362   void operator=(const DUIterator_Fast& that)
1363     { _outp = that._outp;               debug_only(reset(that)); }
1364 };
1365 
1366 DUIterator_Fast Node::fast_outs(DUIterator_Fast& imax) const {
1367   // Assign a limit pointer to the reference argument:
1368   imax = DUIterator_Fast(this, (ptrdiff_t)_outcnt);
1369   // Return the base pointer:
1370   return DUIterator_Fast(this, 0);
1371 }
1372 Node* Node::fast_out(DUIterator_Fast& i) const {
1373   I_VDUI_ONLY(i, i.verify(this));
1374   return debug_only(i._last=) *i._outp;
1375 }
1376 
1377 
1378 // Faster DU iterator.  Requires each successive edge to be removed.
1379 // Does not allow insertion of any edges.
1380 // Usage:
1381 //  for (DUIterator_Last imin, i = x->last_outs(imin); i >= imin; i -= num_edges) {
1382 //    Node* y = x->last_out(i);
1383 //    ...
1384 //  }
1385 // Compiles in product mode to raw Node** pointer arithmetic, with
1386 // no reloading of pointers from the original node x.
1387 class DUIterator_Last : private DUIterator_Fast {
1388   friend class Node;
1389 
1390   #ifdef ASSERT
1391   void verify(const Node* node, bool at_end_ok = false);
1392   void verify_limit();
1393   void verify_step(uint num_edges);
1394   #endif
1395 
1396   // Note:  offset must be signed, since -1 is sometimes passed
1397   DUIterator_Last(const Node* node, ptrdiff_t offset)
1398     : DUIterator_Fast(node, offset) { }
1399 
1400   void operator++(int dummy_to_specify_postfix_op) {} // do not use
1401   void operator<(int)                              {} // do not use
1402 
1403  public:
1404   DUIterator_Last() { }
1405   // initialize to garbage
1406 
1407   void operator--()
1408     { _outp--;              VDUI_ONLY(verify_step(1));  }
1409 
1410   void operator-=(uint n)
1411     { _outp -= n;           VDUI_ONLY(verify_step(n));  }
1412 
1413   bool operator>=(DUIterator_Last& limit) {
1414     I_VDUI_ONLY(*this, this->verify(_node, true));
1415     I_VDUI_ONLY(limit, limit.verify_limit());
1416     return _outp >= limit._outp;
1417   }
1418 
1419   void operator=(const DUIterator_Last& that)
1420     { DUIterator_Fast::operator=(that); }
1421 };
1422 
1423 DUIterator_Last Node::last_outs(DUIterator_Last& imin) const {
1424   // Assign a limit pointer to the reference argument:
1425   imin = DUIterator_Last(this, 0);
1426   // Return the initial pointer:
1427   return DUIterator_Last(this, (ptrdiff_t)_outcnt - 1);
1428 }
1429 Node* Node::last_out(DUIterator_Last& i) const {
1430   I_VDUI_ONLY(i, i.verify(this));
1431   return debug_only(i._last=) *i._outp;
1432 }
1433 
1434 #endif //OPTO_DU_ITERATOR_ASSERT
1435 
1436 #undef I_VDUI_ONLY
1437 #undef VDUI_ONLY
1438 
1439 // An Iterator that truly follows the iterator pattern.  Doesn't
1440 // support deletion but could be made to.
1441 //
1442 //   for (SimpleDUIterator i(n); i.has_next(); i.next()) {
1443 //     Node* m = i.get();
1444 //
1445 class SimpleDUIterator : public StackObj {
1446  private:
1447   Node* node;
1448   DUIterator_Fast i;
1449   DUIterator_Fast imax;
1450  public:
1451   SimpleDUIterator(Node* n): node(n), i(n->fast_outs(imax)) {}
1452   bool has_next() { return i < imax; }
1453   void next() { i++; }
1454   Node* get() { return node->fast_out(i); }
1455 };
1456 
1457 
1458 //-----------------------------------------------------------------------------
1459 // Map dense integer indices to Nodes.  Uses classic doubling-array trick.
1460 // Abstractly provides an infinite array of Node*'s, initialized to NULL.
1461 // Note that the constructor just zeros things, and since I use Arena
1462 // allocation I do not need a destructor to reclaim storage.
1463 class Node_Array : public ResourceObj {
1464   friend class VMStructs;
1465 protected:
1466   Arena *_a;                    // Arena to allocate in
1467   uint   _max;
1468   Node **_nodes;
1469   void   grow( uint i );        // Grow array node to fit
1470 public:
1471   Node_Array(Arena *a) : _a(a), _max(OptoNodeListSize) {
1472     _nodes = NEW_ARENA_ARRAY( a, Node *, OptoNodeListSize );
1473     for( int i = 0; i < OptoNodeListSize; i++ ) {
1474       _nodes[i] = NULL;
1475     }
1476   }
1477 
1478   Node_Array(Node_Array *na) : _a(na->_a), _max(na->_max), _nodes(na->_nodes) {}
1479   Node *operator[] ( uint i ) const // Lookup, or NULL for not mapped
1480   { return (i<_max) ? _nodes[i] : (Node*)NULL; }
1481   Node *at( uint i ) const { assert(i<_max,"oob"); return _nodes[i]; }
1482   Node **adr() { return _nodes; }
1483   // Extend the mapping: index i maps to Node *n.
1484   void map( uint i, Node *n ) { if( i>=_max ) grow(i); _nodes[i] = n; }
1485   void insert( uint i, Node *n );
1486   void remove( uint i );        // Remove, preserving order
1487   void sort( C_sort_func_t func);
1488   void reset( Arena *new_a );   // Zap mapping to empty; reclaim storage
1489   void clear();                 // Set all entries to NULL, keep storage
1490   uint Size() const { return _max; }
1491   void dump() const;
1492 };
1493 
1494 class Node_List : public Node_Array {
1495   friend class VMStructs;
1496   uint _cnt;
1497 public:
1498   Node_List() : Node_Array(Thread::current()->resource_area()), _cnt(0) {}
1499   Node_List(Arena *a) : Node_Array(a), _cnt(0) {}
1500   bool contains(const Node* n) const {
1501     for (uint e = 0; e < size(); e++) {
1502       if (at(e) == n) return true;
1503     }
1504     return false;
1505   }
1506   void insert( uint i, Node *n ) { Node_Array::insert(i,n); _cnt++; }
1507   void remove( uint i ) { Node_Array::remove(i); _cnt--; }
1508   void push( Node *b ) { map(_cnt++,b); }
1509   void yank( Node *n );         // Find and remove
1510   Node *pop() { return _nodes[--_cnt]; }
1511   Node *rpop() { Node *b = _nodes[0]; _nodes[0]=_nodes[--_cnt]; return b;}
1512   void clear() { _cnt = 0; Node_Array::clear(); } // retain storage
1513   uint size() const { return _cnt; }
1514   void dump() const;
1515   void dump_simple() const;
1516 };
1517 
1518 //------------------------------Unique_Node_List-------------------------------
1519 class Unique_Node_List : public Node_List {
1520   friend class VMStructs;
1521   VectorSet _in_worklist;
1522   uint _clock_index;            // Index in list where to pop from next
1523 public:
1524   Unique_Node_List() : Node_List(), _in_worklist(Thread::current()->resource_area()), _clock_index(0) {}
1525   Unique_Node_List(Arena *a) : Node_List(a), _in_worklist(a), _clock_index(0) {}
1526 
1527   void remove( Node *n );
1528   bool member( Node *n ) { return _in_worklist.test(n->_idx) != 0; }
1529   VectorSet &member_set(){ return _in_worklist; }
1530 
1531   void push( Node *b ) {
1532     if( !_in_worklist.test_set(b->_idx) )
1533       Node_List::push(b);
1534   }
1535   Node *pop() {
1536     if( _clock_index >= size() ) _clock_index = 0;
1537     Node *b = at(_clock_index);
1538     map( _clock_index, Node_List::pop());
1539     if (size() != 0) _clock_index++; // Always start from 0
1540     _in_worklist >>= b->_idx;
1541     return b;
1542   }
1543   Node *remove( uint i ) {
1544     Node *b = Node_List::at(i);
1545     _in_worklist >>= b->_idx;
1546     map(i,Node_List::pop());
1547     return b;
1548   }
1549   void yank( Node *n ) { _in_worklist >>= n->_idx; Node_List::yank(n); }
1550   void  clear() {
1551     _in_worklist.Clear();        // Discards storage but grows automatically
1552     Node_List::clear();
1553     _clock_index = 0;
1554   }
1555 
1556   // Used after parsing to remove useless nodes before Iterative GVN
1557   void remove_useless_nodes(VectorSet &useful);
1558 
1559 #ifndef PRODUCT
1560   void print_set() const { _in_worklist.print(); }
1561 #endif
1562 };
1563 
1564 // Inline definition of Compile::record_for_igvn must be deferred to this point.
1565 inline void Compile::record_for_igvn(Node* n) {
1566   _for_igvn->push(n);
1567 }
1568 
1569 //------------------------------Node_Stack-------------------------------------
1570 class Node_Stack {
1571   friend class VMStructs;
1572 protected:
1573   struct INode {
1574     Node *node; // Processed node
1575     uint  indx; // Index of next node's child
1576   };
1577   INode *_inode_top; // tos, stack grows up
1578   INode *_inode_max; // End of _inodes == _inodes + _max
1579   INode *_inodes;    // Array storage for the stack
1580   Arena *_a;         // Arena to allocate in
1581   void grow();
1582 public:
1583   Node_Stack(int size) {
1584     size_t max = (size > OptoNodeListSize) ? size : OptoNodeListSize;
1585     _a = Thread::current()->resource_area();
1586     _inodes = NEW_ARENA_ARRAY( _a, INode, max );
1587     _inode_max = _inodes + max;
1588     _inode_top = _inodes - 1; // stack is empty
1589   }
1590 
1591   Node_Stack(Arena *a, int size) : _a(a) {
1592     size_t max = (size > OptoNodeListSize) ? size : OptoNodeListSize;
1593     _inodes = NEW_ARENA_ARRAY( _a, INode, max );
1594     _inode_max = _inodes + max;
1595     _inode_top = _inodes - 1; // stack is empty
1596   }
1597 
1598   void pop() {
1599     assert(_inode_top >= _inodes, "node stack underflow");
1600     --_inode_top;
1601   }
1602   void push(Node *n, uint i) {
1603     ++_inode_top;
1604     if (_inode_top >= _inode_max) grow();
1605     INode *top = _inode_top; // optimization
1606     top->node = n;
1607     top->indx = i;
1608   }
1609   Node *node() const {
1610     return _inode_top->node;
1611   }
1612   Node* node_at(uint i) const {
1613     assert(_inodes + i <= _inode_top, "in range");
1614     return _inodes[i].node;
1615   }
1616   uint index() const {
1617     return _inode_top->indx;
1618   }
1619   uint index_at(uint i) const {
1620     assert(_inodes + i <= _inode_top, "in range");
1621     return _inodes[i].indx;
1622   }
1623   void set_node(Node *n) {
1624     _inode_top->node = n;
1625   }
1626   void set_index(uint i) {
1627     _inode_top->indx = i;
1628   }
1629   uint size_max() const { return (uint)pointer_delta(_inode_max, _inodes,  sizeof(INode)); } // Max size
1630   uint size() const { return (uint)pointer_delta((_inode_top+1), _inodes,  sizeof(INode)); } // Current size
1631   bool is_nonempty() const { return (_inode_top >= _inodes); }
1632   bool is_empty() const { return (_inode_top < _inodes); }
1633   void clear() { _inode_top = _inodes - 1; } // retain storage
1634 
1635   // Node_Stack is used to map nodes.
1636   Node* find(uint idx) const;
1637 };
1638 
1639 
1640 //-----------------------------Node_Notes--------------------------------------
1641 // Debugging or profiling annotations loosely and sparsely associated
1642 // with some nodes.  See Compile::node_notes_at for the accessor.
1643 class Node_Notes {
1644   friend class VMStructs;
1645   JVMState* _jvms;
1646 
1647 public:
1648   Node_Notes(JVMState* jvms = NULL) {
1649     _jvms = jvms;
1650   }
1651 
1652   JVMState* jvms()            { return _jvms; }
1653   void  set_jvms(JVMState* x) {        _jvms = x; }
1654 
1655   // True if there is nothing here.
1656   bool is_clear() {
1657     return (_jvms == NULL);
1658   }
1659 
1660   // Make there be nothing here.
1661   void clear() {
1662     _jvms = NULL;
1663   }
1664 
1665   // Make a new, clean node notes.
1666   static Node_Notes* make(Compile* C) {
1667     Node_Notes* nn = NEW_ARENA_ARRAY(C->comp_arena(), Node_Notes, 1);
1668     nn->clear();
1669     return nn;
1670   }
1671 
1672   Node_Notes* clone(Compile* C) {
1673     Node_Notes* nn = NEW_ARENA_ARRAY(C->comp_arena(), Node_Notes, 1);
1674     (*nn) = (*this);
1675     return nn;
1676   }
1677 
1678   // Absorb any information from source.
1679   bool update_from(Node_Notes* source) {
1680     bool changed = false;
1681     if (source != NULL) {
1682       if (source->jvms() != NULL) {
1683         set_jvms(source->jvms());
1684         changed = true;
1685       }
1686     }
1687     return changed;
1688   }
1689 };
1690 
1691 // Inlined accessors for Compile::node_nodes that require the preceding class:
1692 inline Node_Notes*
1693 Compile::locate_node_notes(GrowableArray<Node_Notes*>* arr,
1694                            int idx, bool can_grow) {
1695   assert(idx >= 0, "oob");
1696   int block_idx = (idx >> _log2_node_notes_block_size);
1697   int grow_by = (block_idx - (arr == NULL? 0: arr->length()));
1698   if (grow_by >= 0) {
1699     if (!can_grow) return NULL;
1700     grow_node_notes(arr, grow_by + 1);
1701   }
1702   if (arr == NULL) return NULL;
1703   // (Every element of arr is a sub-array of length _node_notes_block_size.)
1704   return arr->at(block_idx) + (idx & (_node_notes_block_size-1));
1705 }
1706 
1707 inline bool
1708 Compile::set_node_notes_at(int idx, Node_Notes* value) {
1709   if (value == NULL || value->is_clear())
1710     return false;  // nothing to write => write nothing
1711   Node_Notes* loc = locate_node_notes(_node_note_array, idx, true);
1712   assert(loc != NULL, "");
1713   return loc->update_from(value);
1714 }
1715 
1716 
1717 //------------------------------TypeNode---------------------------------------
1718 // Node with a Type constant.
1719 class TypeNode : public Node {
1720 protected:
1721   virtual uint hash() const;    // Check the type
1722   virtual uint cmp( const Node &n ) const;
1723   virtual uint size_of() const; // Size is bigger
1724   const Type* const _type;
1725 public:
1726   void set_type(const Type* t) {
1727     assert(t != NULL, "sanity");
1728     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
1729     *(const Type**)&_type = t;   // cast away const-ness
1730     // If this node is in the hash table, make sure it doesn't need a rehash.
1731     assert(check_hash == NO_HASH || check_hash == hash(), "type change must preserve hash code");
1732   }
1733   const Type* type() const { assert(_type != NULL, "sanity"); return _type; };
1734   TypeNode( const Type *t, uint required ) : Node(required), _type(t) {
1735     init_class_id(Class_Type);
1736   }
1737   virtual const Type* Value(PhaseGVN* phase) const;
1738   virtual const Type *bottom_type() const;
1739   virtual       uint  ideal_reg() const;
1740 #ifndef PRODUCT
1741   virtual void dump_spec(outputStream *st) const;
1742   virtual void dump_compact_spec(outputStream *st) const;
1743 #endif
1744 };
1745 
1746 #endif // SHARE_VM_OPTO_NODE_HPP