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