1 /*
   2  * Copyright (c) 1997, 2019, 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_OPTO_NODE_HPP
  26 #define SHARE_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 LoadStoreNode;
  87 class LoadStoreConditionalNode;
  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 MachPrologNode;
 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 ValueTypeBaseNode;
 154 class ValueTypeNode;
 155 class ValueTypePtrNode;
 156 class VectorNode;
 157 class LoadVectorNode;
 158 class StoreVectorNode;
 159 class VectorSet;
 160 typedef void (*NFunc)(Node&,void*);
 161 extern "C" {
 162   typedef int (*C_sort_func_t)(const void *, const void *);
 163 }
 164 
 165 // The type of all node counts and indexes.
 166 // It must hold at least 16 bits, but must also be fast to load and store.
 167 // This type, if less than 32 bits, could limit the number of possible nodes.
 168 // (To make this type platform-specific, move to globalDefinitions_xxx.hpp.)
 169 typedef unsigned int node_idx_t;
 170 
 171 
 172 #ifndef OPTO_DU_ITERATOR_ASSERT
 173 #ifdef ASSERT
 174 #define OPTO_DU_ITERATOR_ASSERT 1
 175 #else
 176 #define OPTO_DU_ITERATOR_ASSERT 0
 177 #endif
 178 #endif //OPTO_DU_ITERATOR_ASSERT
 179 
 180 #if OPTO_DU_ITERATOR_ASSERT
 181 class DUIterator;
 182 class DUIterator_Fast;
 183 class DUIterator_Last;
 184 #else
 185 typedef uint   DUIterator;
 186 typedef Node** DUIterator_Fast;
 187 typedef Node** DUIterator_Last;
 188 #endif
 189 
 190 // Node Sentinel
 191 #define NodeSentinel (Node*)-1
 192 
 193 // Unknown count frequency
 194 #define COUNT_UNKNOWN (-1.0f)
 195 
 196 //------------------------------Node-------------------------------------------
 197 // Nodes define actions in the program.  They create values, which have types.
 198 // They are both vertices in a directed graph and program primitives.  Nodes
 199 // are labeled; the label is the "opcode", the primitive function in the lambda
 200 // calculus sense that gives meaning to the Node.  Node inputs are ordered (so
 201 // that "a-b" is different from "b-a").  The inputs to a Node are the inputs to
 202 // the Node's function.  These inputs also define a Type equation for the Node.
 203 // Solving these Type equations amounts to doing dataflow analysis.
 204 // Control and data are uniformly represented in the graph.  Finally, Nodes
 205 // have a unique dense integer index which is used to index into side arrays
 206 // whenever I have phase-specific information.
 207 
 208 class Node {
 209   friend class VMStructs;
 210 
 211   // Lots of restrictions on cloning Nodes
 212   Node(const Node&);            // not defined; linker error to use these
 213   Node &operator=(const Node &rhs);
 214 
 215 public:
 216   friend class Compile;
 217   #if OPTO_DU_ITERATOR_ASSERT
 218   friend class DUIterator_Common;
 219   friend class DUIterator;
 220   friend class DUIterator_Fast;
 221   friend class DUIterator_Last;
 222   #endif
 223 
 224   // Because Nodes come and go, I define an Arena of Node structures to pull
 225   // from.  This should allow fast access to node creation & deletion.  This
 226   // field is a local cache of a value defined in some "program fragment" for
 227   // which these Nodes are just a part of.
 228 
 229   inline void* operator new(size_t x) throw() {
 230     Compile* C = Compile::current();
 231     Node* n = (Node*)C->node_arena()->Amalloc_D(x);
 232     return (void*)n;
 233   }
 234 
 235   // Delete is a NOP
 236   void operator delete( void *ptr ) {}
 237   // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 238   void destruct();
 239 
 240   // Create a new Node.  Required is the number is of inputs required for
 241   // semantic correctness.
 242   Node( uint required );
 243 
 244   // Create a new Node with given input edges.
 245   // This version requires use of the "edge-count" new.
 246   // E.g.  new (C,3) FooNode( C, NULL, left, right );
 247   Node( Node *n0 );
 248   Node( Node *n0, Node *n1 );
 249   Node( Node *n0, Node *n1, Node *n2 );
 250   Node( Node *n0, Node *n1, Node *n2, Node *n3 );
 251   Node( Node *n0, Node *n1, Node *n2, Node *n3, Node *n4 );
 252   Node( Node *n0, Node *n1, Node *n2, Node *n3, Node *n4, Node *n5 );
 253   Node( Node *n0, Node *n1, Node *n2, Node *n3,
 254             Node *n4, Node *n5, Node *n6 );
 255 
 256   // Clone an inherited Node given only the base Node type.
 257   Node* clone() const;
 258 
 259   // Clone a Node, immediately supplying one or two new edges.
 260   // The first and second arguments, if non-null, replace in(1) and in(2),
 261   // respectively.
 262   Node* clone_with_data_edge(Node* in1, Node* in2 = NULL) const {
 263     Node* nn = clone();
 264     if (in1 != NULL)  nn->set_req(1, in1);
 265     if (in2 != NULL)  nn->set_req(2, in2);
 266     return nn;
 267   }
 268 
 269 private:
 270   // Shared setup for the above constructors.
 271   // Handles all interactions with Compile::current.
 272   // Puts initial values in all Node fields except _idx.
 273   // Returns the initial value for _idx, which cannot
 274   // be initialized by assignment.
 275   inline int Init(int req);
 276 
 277 //----------------- input edge handling
 278 protected:
 279   friend class PhaseCFG;        // Access to address of _in array elements
 280   Node **_in;                   // Array of use-def references to Nodes
 281   Node **_out;                  // Array of def-use references to Nodes
 282 
 283   // Input edges are split into two categories.  Required edges are required
 284   // for semantic correctness; order is important and NULLs are allowed.
 285   // Precedence edges are used to help determine execution order and are
 286   // added, e.g., for scheduling purposes.  They are unordered and not
 287   // duplicated; they have no embedded NULLs.  Edges from 0 to _cnt-1
 288   // are required, from _cnt to _max-1 are precedence edges.
 289   node_idx_t _cnt;              // Total number of required Node inputs.
 290 
 291   node_idx_t _max;              // Actual length of input array.
 292 
 293   // Output edges are an unordered list of def-use edges which exactly
 294   // correspond to required input edges which point from other nodes
 295   // to this one.  Thus the count of the output edges is the number of
 296   // users of this node.
 297   node_idx_t _outcnt;           // Total number of Node outputs.
 298 
 299   node_idx_t _outmax;           // Actual length of output array.
 300 
 301   // Grow the actual input array to the next larger power-of-2 bigger than len.
 302   void grow( uint len );
 303   // Grow the output array to the next larger power-of-2 bigger than len.
 304   void out_grow( uint len );
 305 
 306  public:
 307   // Each Node is assigned a unique small/dense number.  This number is used
 308   // to index into auxiliary arrays of data and bit vectors.
 309   // The field _idx is declared constant to defend against inadvertent assignments,
 310   // since it is used by clients as a naked field. However, the field's value can be
 311   // changed using the set_idx() method.
 312   //
 313   // The PhaseRenumberLive phase renumbers nodes based on liveness information.
 314   // Therefore, it updates the value of the _idx field. The parse-time _idx is
 315   // preserved in _parse_idx.
 316   const node_idx_t _idx;
 317   DEBUG_ONLY(const node_idx_t _parse_idx;)
 318 
 319   // Get the (read-only) number of input edges
 320   uint req() const { return _cnt; }
 321   uint len() const { return _max; }
 322   // Get the (read-only) number of output edges
 323   uint outcnt() const { return _outcnt; }
 324 
 325 #if OPTO_DU_ITERATOR_ASSERT
 326   // Iterate over the out-edges of this node.  Deletions are illegal.
 327   inline DUIterator outs() const;
 328   // Use this when the out array might have changed to suppress asserts.
 329   inline DUIterator& refresh_out_pos(DUIterator& i) const;
 330   // Does the node have an out at this position?  (Used for iteration.)
 331   inline bool has_out(DUIterator& i) const;
 332   inline Node*    out(DUIterator& i) const;
 333   // Iterate over the out-edges of this node.  All changes are illegal.
 334   inline DUIterator_Fast fast_outs(DUIterator_Fast& max) const;
 335   inline Node*    fast_out(DUIterator_Fast& i) const;
 336   // Iterate over the out-edges of this node, deleting one at a time.
 337   inline DUIterator_Last last_outs(DUIterator_Last& min) const;
 338   inline Node*    last_out(DUIterator_Last& i) const;
 339   // The inline bodies of all these methods are after the iterator definitions.
 340 #else
 341   // Iterate over the out-edges of this node.  Deletions are illegal.
 342   // This iteration uses integral indexes, to decouple from array reallocations.
 343   DUIterator outs() const  { return 0; }
 344   // Use this when the out array might have changed to suppress asserts.
 345   DUIterator refresh_out_pos(DUIterator i) const { return i; }
 346 
 347   // Reference to the i'th output Node.  Error if out of bounds.
 348   Node*    out(DUIterator i) const { assert(i < _outcnt, "oob"); return _out[i]; }
 349   // Does the node have an out at this position?  (Used for iteration.)
 350   bool has_out(DUIterator i) const { return i < _outcnt; }
 351 
 352   // Iterate over the out-edges of this node.  All changes are illegal.
 353   // This iteration uses a pointer internal to the out array.
 354   DUIterator_Fast fast_outs(DUIterator_Fast& max) const {
 355     Node** out = _out;
 356     // Assign a limit pointer to the reference argument:
 357     max = out + (ptrdiff_t)_outcnt;
 358     // Return the base pointer:
 359     return out;
 360   }
 361   Node*    fast_out(DUIterator_Fast i) const  { return *i; }
 362   // Iterate over the out-edges of this node, deleting one at a time.
 363   // This iteration uses a pointer internal to the out array.
 364   DUIterator_Last last_outs(DUIterator_Last& min) const {
 365     Node** out = _out;
 366     // Assign a limit pointer to the reference argument:
 367     min = out;
 368     // Return the pointer to the start of the iteration:
 369     return out + (ptrdiff_t)_outcnt - 1;
 370   }
 371   Node*    last_out(DUIterator_Last i) const  { return *i; }
 372 #endif
 373 
 374   // Reference to the i'th input Node.  Error if out of bounds.
 375   Node* in(uint i) const { assert(i < _max, "oob: i=%d, _max=%d", i, _max); return _in[i]; }
 376   // Reference to the i'th input Node.  NULL if out of bounds.
 377   Node* lookup(uint i) const { return ((i < _max) ? _in[i] : NULL); }
 378   // Reference to the i'th output Node.  Error if out of bounds.
 379   // Use this accessor sparingly.  We are going trying to use iterators instead.
 380   Node* raw_out(uint i) const { assert(i < _outcnt,"oob"); return _out[i]; }
 381   // Return the unique out edge.
 382   Node* unique_out() const { assert(_outcnt==1,"not unique"); return _out[0]; }
 383   // Delete out edge at position 'i' by moving last out edge to position 'i'
 384   void  raw_del_out(uint i) {
 385     assert(i < _outcnt,"oob");
 386     assert(_outcnt > 0,"oob");
 387     #if OPTO_DU_ITERATOR_ASSERT
 388     // Record that a change happened here.
 389     debug_only(_last_del = _out[i]; ++_del_tick);
 390     #endif
 391     _out[i] = _out[--_outcnt];
 392     // Smash the old edge so it can't be used accidentally.
 393     debug_only(_out[_outcnt] = (Node *)(uintptr_t)0xdeadbeef);
 394   }
 395 
 396 #ifdef ASSERT
 397   bool is_dead() const;
 398 #define is_not_dead(n) ((n) == NULL || !VerifyIterativeGVN || !((n)->is_dead()))
 399 #endif
 400   // Check whether node has become unreachable
 401   bool is_unreachable(PhaseIterGVN &igvn) const;
 402 
 403   // Set a required input edge, also updates corresponding output edge
 404   void add_req( Node *n ); // Append a NEW required input
 405   void add_req( Node *n0, Node *n1 ) {
 406     add_req(n0); add_req(n1); }
 407   void add_req( Node *n0, Node *n1, Node *n2 ) {
 408     add_req(n0); add_req(n1); add_req(n2); }
 409   void add_req_batch( Node* n, uint m ); // Append m NEW required inputs (all n).
 410   void del_req( uint idx ); // Delete required edge & compact
 411   void del_req_ordered( uint idx ); // Delete required edge & compact with preserved order
 412   void ins_req( uint i, Node *n ); // Insert a NEW required input
 413   void set_req( uint i, Node *n ) {
 414     assert( is_not_dead(n), "can not use dead node");
 415     assert( i < _cnt, "oob: i=%d, _cnt=%d", i, _cnt);
 416     assert( !VerifyHashTableKeys || _hash_lock == 0,
 417             "remove node from hash table before modifying it");
 418     Node** p = &_in[i];    // cache this._in, across the del_out call
 419     if (*p != NULL)  (*p)->del_out((Node *)this);
 420     (*p) = n;
 421     if (n != NULL)      n->add_out((Node *)this);
 422     Compile::current()->record_modified_node(this);
 423   }
 424   // Light version of set_req() to init inputs after node creation.
 425   void init_req( uint i, Node *n ) {
 426     assert( i == 0 && this == n ||
 427             is_not_dead(n), "can not use dead node");
 428     assert( i < _cnt, "oob");
 429     assert( !VerifyHashTableKeys || _hash_lock == 0,
 430             "remove node from hash table before modifying it");
 431     assert( _in[i] == NULL, "sanity");
 432     _in[i] = n;
 433     if (n != NULL)      n->add_out((Node *)this);
 434     Compile::current()->record_modified_node(this);
 435   }
 436   // Find first occurrence of n among my edges:
 437   int find_edge(Node* n);
 438   int find_prec_edge(Node* n) {
 439     for (uint i = req(); i < len(); i++) {
 440       if (_in[i] == n) return i;
 441       if (_in[i] == NULL) {
 442         DEBUG_ONLY( while ((++i) < len()) assert(_in[i] == NULL, "Gap in prec edges!"); )
 443         break;
 444       }
 445     }
 446     return -1;
 447   }
 448   int replace_edge(Node* old, Node* neww);
 449   int replace_edges_in_range(Node* old, Node* neww, int start, int end);
 450   // NULL out all inputs to eliminate incoming Def-Use edges.
 451   // Return the number of edges between 'n' and 'this'
 452   int  disconnect_inputs(Node *n, Compile *c);
 453 
 454   // Quickly, return true if and only if I am Compile::current()->top().
 455   bool is_top() const {
 456     assert((this == (Node*) Compile::current()->top()) == (_out == NULL), "");
 457     return (_out == NULL);
 458   }
 459   // Reaffirm invariants for is_top.  (Only from Compile::set_cached_top_node.)
 460   void setup_is_top();
 461 
 462   // Strip away casting.  (It is depth-limited.)
 463   Node* uncast(bool keep_deps = false) const;
 464   // Return whether two Nodes are equivalent, after stripping casting.
 465   bool eqv_uncast(const Node* n, bool keep_deps = false) const {
 466     return (this->uncast(keep_deps) == n->uncast(keep_deps));
 467   }
 468 
 469   // Find out of current node that matches opcode.
 470   Node* find_out_with(int opcode);
 471   // Return true if the current node has an out that matches opcode.
 472   bool has_out_with(int opcode);
 473   // Return true if the current node has an out that matches any of the opcodes.
 474   bool has_out_with(int opcode1, int opcode2, int opcode3, int opcode4);
 475 
 476 private:
 477   static Node* uncast_helper(const Node* n, bool keep_deps);
 478 
 479   // Add an output edge to the end of the list
 480   void add_out( Node *n ) {
 481     if (is_top())  return;
 482     if( _outcnt == _outmax ) out_grow(_outcnt);
 483     _out[_outcnt++] = n;
 484   }
 485   // Delete an output edge
 486   void del_out( Node *n ) {
 487     if (is_top())  return;
 488     Node** outp = &_out[_outcnt];
 489     // Find and remove n
 490     do {
 491       assert(outp > _out, "Missing Def-Use edge");
 492     } while (*--outp != n);
 493     *outp = _out[--_outcnt];
 494     // Smash the old edge so it can't be used accidentally.
 495     debug_only(_out[_outcnt] = (Node *)(uintptr_t)0xdeadbeef);
 496     // Record that a change happened here.
 497     #if OPTO_DU_ITERATOR_ASSERT
 498     debug_only(_last_del = n; ++_del_tick);
 499     #endif
 500   }
 501   // Close gap after removing edge.
 502   void close_prec_gap_at(uint gap) {
 503     assert(_cnt <= gap && gap < _max, "no valid prec edge");
 504     uint i = gap;
 505     Node *last = NULL;
 506     for (; i < _max-1; ++i) {
 507       Node *next = _in[i+1];
 508       if (next == NULL) break;
 509       last = next;
 510     }
 511     _in[gap] = last; // Move last slot to empty one.
 512     _in[i] = NULL;   // NULL out last slot.
 513   }
 514 
 515 public:
 516   // Globally replace this node by a given new node, updating all uses.
 517   void replace_by(Node* new_node);
 518   // Globally replace this node by a given new node, updating all uses
 519   // and cutting input edges of old node.
 520   void subsume_by(Node* new_node, Compile* c) {
 521     replace_by(new_node);
 522     disconnect_inputs(NULL, c);
 523   }
 524   void set_req_X( uint i, Node *n, PhaseIterGVN *igvn );
 525   // Find the one non-null required input.  RegionNode only
 526   Node *nonnull_req() const;
 527   // Add or remove precedence edges
 528   void add_prec( Node *n );
 529   void rm_prec( uint i );
 530 
 531   // Note: prec(i) will not necessarily point to n if edge already exists.
 532   void set_prec( uint i, Node *n ) {
 533     assert(i < _max, "oob: i=%d, _max=%d", i, _max);
 534     assert(is_not_dead(n), "can not use dead node");
 535     assert(i >= _cnt, "not a precedence edge");
 536     // Avoid spec violation: duplicated prec edge.
 537     if (_in[i] == n) return;
 538     if (n == NULL || find_prec_edge(n) != -1) {
 539       rm_prec(i);
 540       return;
 541     }
 542     if (_in[i] != NULL) _in[i]->del_out((Node *)this);
 543     _in[i] = n;
 544     if (n != NULL) n->add_out((Node *)this);
 545   }
 546 
 547   // Set this node's index, used by cisc_version to replace current node
 548   void set_idx(uint new_idx) {
 549     const node_idx_t* ref = &_idx;
 550     *(node_idx_t*)ref = new_idx;
 551   }
 552   // Swap input edge order.  (Edge indexes i1 and i2 are usually 1 and 2.)
 553   void swap_edges(uint i1, uint i2) {
 554     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
 555     // Def-Use info is unchanged
 556     Node* n1 = in(i1);
 557     Node* n2 = in(i2);
 558     _in[i1] = n2;
 559     _in[i2] = n1;
 560     // If this node is in the hash table, make sure it doesn't need a rehash.
 561     assert(check_hash == NO_HASH || check_hash == hash(), "edge swap must preserve hash code");
 562   }
 563 
 564   // Iterators over input Nodes for a Node X are written as:
 565   // for( i = 0; i < X.req(); i++ ) ... X[i] ...
 566   // NOTE: Required edges can contain embedded NULL pointers.
 567 
 568 //----------------- Other Node Properties
 569 
 570   // Generate class IDs for (some) ideal nodes so that it is possible to determine
 571   // the type of a node using a non-virtual method call (the method is_<Node>() below).
 572   //
 573   // A class ID of an ideal node is a set of bits. In a class ID, a single bit determines
 574   // the type of the node the ID represents; another subset of an ID's bits are reserved
 575   // for the superclasses of the node represented by the ID.
 576   //
 577   // By design, if A is a supertype of B, A.is_B() returns true and B.is_A()
 578   // returns false. A.is_A() returns true.
 579   //
 580   // If two classes, A and B, have the same superclass, a different bit of A's class id
 581   // is reserved for A's type than for B's type. That bit is specified by the third
 582   // parameter in the macro DEFINE_CLASS_ID.
 583   //
 584   // By convention, classes with deeper hierarchy are declared first. Moreover,
 585   // classes with the same hierarchy depth are sorted by usage frequency.
 586   //
 587   // The query method masks the bits to cut off bits of subclasses and then compares
 588   // the result with the class id (see the macro DEFINE_CLASS_QUERY below).
 589   //
 590   //  Class_MachCall=30, ClassMask_MachCall=31
 591   // 12               8               4               0
 592   //  0   0   0   0   0   0   0   0   1   1   1   1   0
 593   //                                  |   |   |   |
 594   //                                  |   |   |   Bit_Mach=2
 595   //                                  |   |   Bit_MachReturn=4
 596   //                                  |   Bit_MachSafePoint=8
 597   //                                  Bit_MachCall=16
 598   //
 599   //  Class_CountedLoop=56, ClassMask_CountedLoop=63
 600   // 12               8               4               0
 601   //  0   0   0   0   0   0   0   1   1   1   0   0   0
 602   //                              |   |   |
 603   //                              |   |   Bit_Region=8
 604   //                              |   Bit_Loop=16
 605   //                              Bit_CountedLoop=32
 606 
 607   #define DEFINE_CLASS_ID(cl, supcl, subn) \
 608   Bit_##cl = (Class_##supcl == 0) ? 1 << subn : (Bit_##supcl) << (1 + subn) , \
 609   Class_##cl = Class_##supcl + Bit_##cl , \
 610   ClassMask_##cl = ((Bit_##cl << 1) - 1) ,
 611 
 612   // This enum is used only for C2 ideal and mach nodes with is_<node>() methods
 613   // so that it's values fits into 16 bits.
 614   enum NodeClasses {
 615     Bit_Node   = 0x0000,
 616     Class_Node = 0x0000,
 617     ClassMask_Node = 0xFFFF,
 618 
 619     DEFINE_CLASS_ID(Multi, Node, 0)
 620       DEFINE_CLASS_ID(SafePoint, Multi, 0)
 621         DEFINE_CLASS_ID(Call,      SafePoint, 0)
 622           DEFINE_CLASS_ID(CallJava,         Call, 0)
 623             DEFINE_CLASS_ID(CallStaticJava,   CallJava, 0)
 624             DEFINE_CLASS_ID(CallDynamicJava,  CallJava, 1)
 625           DEFINE_CLASS_ID(CallRuntime,      Call, 1)
 626             DEFINE_CLASS_ID(CallLeaf,         CallRuntime, 0)
 627           DEFINE_CLASS_ID(Allocate,         Call, 2)
 628             DEFINE_CLASS_ID(AllocateArray,    Allocate, 0)
 629           DEFINE_CLASS_ID(AbstractLock,     Call, 3)
 630             DEFINE_CLASS_ID(Lock,             AbstractLock, 0)
 631             DEFINE_CLASS_ID(Unlock,           AbstractLock, 1)
 632           DEFINE_CLASS_ID(ArrayCopy,        Call, 4)
 633       DEFINE_CLASS_ID(MultiBranch, Multi, 1)
 634         DEFINE_CLASS_ID(PCTable,     MultiBranch, 0)
 635           DEFINE_CLASS_ID(Catch,       PCTable, 0)
 636           DEFINE_CLASS_ID(Jump,        PCTable, 1)
 637         DEFINE_CLASS_ID(If,          MultiBranch, 1)
 638           DEFINE_CLASS_ID(CountedLoopEnd,         If, 0)
 639           DEFINE_CLASS_ID(RangeCheck,             If, 1)
 640           DEFINE_CLASS_ID(OuterStripMinedLoopEnd, If, 2)
 641         DEFINE_CLASS_ID(NeverBranch, MultiBranch, 2)
 642       DEFINE_CLASS_ID(Start,       Multi, 2)
 643       DEFINE_CLASS_ID(MemBar,      Multi, 3)
 644         DEFINE_CLASS_ID(Initialize,       MemBar, 0)
 645         DEFINE_CLASS_ID(MemBarStoreStore, MemBar, 1)
 646       DEFINE_CLASS_ID(LoadBarrier, Multi, 4)
 647 
 648     DEFINE_CLASS_ID(Mach,  Node, 1)
 649       DEFINE_CLASS_ID(MachReturn, Mach, 0)
 650         DEFINE_CLASS_ID(MachSafePoint, MachReturn, 0)
 651           DEFINE_CLASS_ID(MachCall, MachSafePoint, 0)
 652             DEFINE_CLASS_ID(MachCallJava,         MachCall, 0)
 653               DEFINE_CLASS_ID(MachCallStaticJava,   MachCallJava, 0)
 654               DEFINE_CLASS_ID(MachCallDynamicJava,  MachCallJava, 1)
 655             DEFINE_CLASS_ID(MachCallRuntime,      MachCall, 1)
 656               DEFINE_CLASS_ID(MachCallLeaf,         MachCallRuntime, 0)
 657       DEFINE_CLASS_ID(MachBranch, Mach, 1)
 658         DEFINE_CLASS_ID(MachIf,         MachBranch, 0)
 659         DEFINE_CLASS_ID(MachGoto,       MachBranch, 1)
 660         DEFINE_CLASS_ID(MachNullCheck,  MachBranch, 2)
 661       DEFINE_CLASS_ID(MachSpillCopy,    Mach, 2)
 662       DEFINE_CLASS_ID(MachTemp,         Mach, 3)
 663       DEFINE_CLASS_ID(MachConstantBase, Mach, 4)
 664       DEFINE_CLASS_ID(MachConstant,     Mach, 5)
 665         DEFINE_CLASS_ID(MachJump,       MachConstant, 0)
 666       DEFINE_CLASS_ID(MachMerge,        Mach, 6)
 667       DEFINE_CLASS_ID(MachMemBar,       Mach, 7)
 668       DEFINE_CLASS_ID(MachProlog,       Mach, 8)
 669 
 670     DEFINE_CLASS_ID(Type,  Node, 2)
 671       DEFINE_CLASS_ID(Phi,   Type, 0)
 672       DEFINE_CLASS_ID(ConstraintCast, Type, 1)
 673         DEFINE_CLASS_ID(CastII, ConstraintCast, 0)
 674         DEFINE_CLASS_ID(CheckCastPP, ConstraintCast, 1)
 675       DEFINE_CLASS_ID(CMove, Type, 3)
 676       DEFINE_CLASS_ID(SafePointScalarObject, Type, 4)
 677       DEFINE_CLASS_ID(DecodeNarrowPtr, Type, 5)
 678         DEFINE_CLASS_ID(DecodeN, DecodeNarrowPtr, 0)
 679         DEFINE_CLASS_ID(DecodeNKlass, DecodeNarrowPtr, 1)
 680       DEFINE_CLASS_ID(EncodeNarrowPtr, Type, 6)
 681         DEFINE_CLASS_ID(EncodeP, EncodeNarrowPtr, 0)
 682         DEFINE_CLASS_ID(EncodePKlass, EncodeNarrowPtr, 1)
 683       DEFINE_CLASS_ID(ValueTypeBase, Type, 8)
 684         DEFINE_CLASS_ID(ValueType, ValueTypeBase, 0)
 685         DEFINE_CLASS_ID(ValueTypePtr, ValueTypeBase, 1)
 686 
 687     DEFINE_CLASS_ID(Proj,  Node, 3)
 688       DEFINE_CLASS_ID(CatchProj, Proj, 0)
 689       DEFINE_CLASS_ID(JumpProj,  Proj, 1)
 690       DEFINE_CLASS_ID(IfProj,    Proj, 2)
 691         DEFINE_CLASS_ID(IfTrue,    IfProj, 0)
 692         DEFINE_CLASS_ID(IfFalse,   IfProj, 1)
 693       DEFINE_CLASS_ID(Parm,      Proj, 4)
 694       DEFINE_CLASS_ID(MachProj,  Proj, 5)
 695 
 696     DEFINE_CLASS_ID(Mem,   Node, 4)
 697       DEFINE_CLASS_ID(Load,  Mem, 0)
 698         DEFINE_CLASS_ID(LoadVector,  Load, 0)
 699         DEFINE_CLASS_ID(LoadBarrierSlowReg, Load, 1)
 700       DEFINE_CLASS_ID(Store, Mem, 1)
 701         DEFINE_CLASS_ID(StoreVector, Store, 0)
 702       DEFINE_CLASS_ID(LoadStore, Mem, 2)
 703         DEFINE_CLASS_ID(LoadStoreConditional, LoadStore, 0)
 704           DEFINE_CLASS_ID(CompareAndSwap, LoadStoreConditional, 0)
 705         DEFINE_CLASS_ID(CompareAndExchangeNode, LoadStore, 1)
 706 
 707     DEFINE_CLASS_ID(Region, Node, 5)
 708       DEFINE_CLASS_ID(Loop, Region, 0)
 709         DEFINE_CLASS_ID(Root,                Loop, 0)
 710         DEFINE_CLASS_ID(CountedLoop,         Loop, 1)
 711         DEFINE_CLASS_ID(OuterStripMinedLoop, Loop, 2)
 712 
 713     DEFINE_CLASS_ID(Sub,   Node, 6)
 714       DEFINE_CLASS_ID(Cmp,   Sub, 0)
 715         DEFINE_CLASS_ID(FastLock,   Cmp, 0)
 716         DEFINE_CLASS_ID(FastUnlock, Cmp, 1)
 717 
 718     DEFINE_CLASS_ID(MergeMem, Node, 7)
 719     DEFINE_CLASS_ID(Bool,     Node, 8)
 720     DEFINE_CLASS_ID(AddP,     Node, 9)
 721     DEFINE_CLASS_ID(BoxLock,  Node, 10)
 722     DEFINE_CLASS_ID(Add,      Node, 11)
 723     DEFINE_CLASS_ID(Mul,      Node, 12)
 724     DEFINE_CLASS_ID(Vector,   Node, 13)
 725     DEFINE_CLASS_ID(ClearArray, Node, 14)
 726 
 727     _max_classes  = ClassMask_ClearArray
 728   };
 729   #undef DEFINE_CLASS_ID
 730 
 731   // Flags are sorted by usage frequency.
 732   enum NodeFlags {
 733     Flag_is_Copy                     = 0x01, // should be first bit to avoid shift
 734     Flag_rematerialize               = Flag_is_Copy << 1,
 735     Flag_needs_anti_dependence_check = Flag_rematerialize << 1,
 736     Flag_is_macro                    = Flag_needs_anti_dependence_check << 1,
 737     Flag_is_Con                      = Flag_is_macro << 1,
 738     Flag_is_cisc_alternate           = Flag_is_Con << 1,
 739     Flag_is_dead_loop_safe           = Flag_is_cisc_alternate << 1,
 740     Flag_may_be_short_branch         = Flag_is_dead_loop_safe << 1,
 741     Flag_avoid_back_to_back_before   = Flag_may_be_short_branch << 1,
 742     Flag_avoid_back_to_back_after    = Flag_avoid_back_to_back_before << 1,
 743     Flag_has_call                    = Flag_avoid_back_to_back_after << 1,
 744     Flag_is_reduction                = Flag_has_call << 1,
 745     Flag_is_scheduled                = Flag_is_reduction << 1,
 746     Flag_has_vector_mask_set         = Flag_is_scheduled << 1,
 747     Flag_is_expensive                = Flag_has_vector_mask_set << 1,
 748     _max_flags = (Flag_is_expensive << 1) - 1 // allow flags combination
 749   };
 750 
 751 private:
 752   jushort _class_id;
 753   jushort _flags;
 754 
 755 protected:
 756   // These methods should be called from constructors only.
 757   void init_class_id(jushort c) {
 758     assert(c <= _max_classes, "invalid node class");
 759     _class_id = c; // cast out const
 760   }
 761   void init_flags(jushort fl) {
 762     assert(fl <= _max_flags, "invalid node flag");
 763     _flags |= fl;
 764   }
 765   void clear_flag(jushort fl) {
 766     assert(fl <= _max_flags, "invalid node flag");
 767     _flags &= ~fl;
 768   }
 769 
 770 public:
 771   const jushort class_id() const { return _class_id; }
 772 
 773   const jushort flags() const { return _flags; }
 774 
 775   void add_flag(jushort fl) { init_flags(fl); }
 776 
 777   void remove_flag(jushort fl) { clear_flag(fl); }
 778 
 779   // Return a dense integer opcode number
 780   virtual int Opcode() const;
 781 
 782   // Virtual inherited Node size
 783   virtual uint size_of() const;
 784 
 785   // Other interesting Node properties
 786   #define DEFINE_CLASS_QUERY(type)                           \
 787   bool is_##type() const {                                   \
 788     return ((_class_id & ClassMask_##type) == Class_##type); \
 789   }                                                          \
 790   type##Node *as_##type() const {                            \
 791     assert(is_##type(), "invalid node class");               \
 792     return (type##Node*)this;                                \
 793   }                                                          \
 794   type##Node* isa_##type() const {                           \
 795     return (is_##type()) ? as_##type() : NULL;               \
 796   }
 797 
 798   DEFINE_CLASS_QUERY(AbstractLock)
 799   DEFINE_CLASS_QUERY(Add)
 800   DEFINE_CLASS_QUERY(AddP)
 801   DEFINE_CLASS_QUERY(Allocate)
 802   DEFINE_CLASS_QUERY(AllocateArray)
 803   DEFINE_CLASS_QUERY(ArrayCopy)
 804   DEFINE_CLASS_QUERY(Bool)
 805   DEFINE_CLASS_QUERY(BoxLock)
 806   DEFINE_CLASS_QUERY(Call)
 807   DEFINE_CLASS_QUERY(CallDynamicJava)
 808   DEFINE_CLASS_QUERY(CallJava)
 809   DEFINE_CLASS_QUERY(CallLeaf)
 810   DEFINE_CLASS_QUERY(CallRuntime)
 811   DEFINE_CLASS_QUERY(CallStaticJava)
 812   DEFINE_CLASS_QUERY(Catch)
 813   DEFINE_CLASS_QUERY(CatchProj)
 814   DEFINE_CLASS_QUERY(CheckCastPP)
 815   DEFINE_CLASS_QUERY(CastII)
 816   DEFINE_CLASS_QUERY(ConstraintCast)
 817   DEFINE_CLASS_QUERY(ClearArray)
 818   DEFINE_CLASS_QUERY(CMove)
 819   DEFINE_CLASS_QUERY(Cmp)
 820   DEFINE_CLASS_QUERY(CountedLoop)
 821   DEFINE_CLASS_QUERY(CountedLoopEnd)
 822   DEFINE_CLASS_QUERY(DecodeNarrowPtr)
 823   DEFINE_CLASS_QUERY(DecodeN)
 824   DEFINE_CLASS_QUERY(DecodeNKlass)
 825   DEFINE_CLASS_QUERY(EncodeNarrowPtr)
 826   DEFINE_CLASS_QUERY(EncodeP)
 827   DEFINE_CLASS_QUERY(EncodePKlass)
 828   DEFINE_CLASS_QUERY(FastLock)
 829   DEFINE_CLASS_QUERY(FastUnlock)
 830   DEFINE_CLASS_QUERY(If)
 831   DEFINE_CLASS_QUERY(RangeCheck)
 832   DEFINE_CLASS_QUERY(IfProj)
 833   DEFINE_CLASS_QUERY(IfFalse)
 834   DEFINE_CLASS_QUERY(IfTrue)
 835   DEFINE_CLASS_QUERY(Initialize)
 836   DEFINE_CLASS_QUERY(Jump)
 837   DEFINE_CLASS_QUERY(JumpProj)
 838   DEFINE_CLASS_QUERY(Load)
 839   DEFINE_CLASS_QUERY(LoadStore)
 840   DEFINE_CLASS_QUERY(LoadStoreConditional)
 841   DEFINE_CLASS_QUERY(LoadBarrier)
 842   DEFINE_CLASS_QUERY(LoadBarrierSlowReg)
 843   DEFINE_CLASS_QUERY(Lock)
 844   DEFINE_CLASS_QUERY(Loop)
 845   DEFINE_CLASS_QUERY(Mach)
 846   DEFINE_CLASS_QUERY(MachBranch)
 847   DEFINE_CLASS_QUERY(MachCall)
 848   DEFINE_CLASS_QUERY(MachCallDynamicJava)
 849   DEFINE_CLASS_QUERY(MachCallJava)
 850   DEFINE_CLASS_QUERY(MachCallLeaf)
 851   DEFINE_CLASS_QUERY(MachCallRuntime)
 852   DEFINE_CLASS_QUERY(MachCallStaticJava)
 853   DEFINE_CLASS_QUERY(MachConstantBase)
 854   DEFINE_CLASS_QUERY(MachConstant)
 855   DEFINE_CLASS_QUERY(MachGoto)
 856   DEFINE_CLASS_QUERY(MachIf)
 857   DEFINE_CLASS_QUERY(MachJump)
 858   DEFINE_CLASS_QUERY(MachNullCheck)
 859   DEFINE_CLASS_QUERY(MachProj)
 860   DEFINE_CLASS_QUERY(MachProlog)
 861   DEFINE_CLASS_QUERY(MachReturn)
 862   DEFINE_CLASS_QUERY(MachSafePoint)
 863   DEFINE_CLASS_QUERY(MachSpillCopy)
 864   DEFINE_CLASS_QUERY(MachTemp)
 865   DEFINE_CLASS_QUERY(MachMemBar)
 866   DEFINE_CLASS_QUERY(MachMerge)
 867   DEFINE_CLASS_QUERY(Mem)
 868   DEFINE_CLASS_QUERY(MemBar)
 869   DEFINE_CLASS_QUERY(MemBarStoreStore)
 870   DEFINE_CLASS_QUERY(MergeMem)
 871   DEFINE_CLASS_QUERY(Mul)
 872   DEFINE_CLASS_QUERY(Multi)
 873   DEFINE_CLASS_QUERY(MultiBranch)
 874   DEFINE_CLASS_QUERY(OuterStripMinedLoop)
 875   DEFINE_CLASS_QUERY(OuterStripMinedLoopEnd)
 876   DEFINE_CLASS_QUERY(Parm)
 877   DEFINE_CLASS_QUERY(PCTable)
 878   DEFINE_CLASS_QUERY(Phi)
 879   DEFINE_CLASS_QUERY(Proj)
 880   DEFINE_CLASS_QUERY(Region)
 881   DEFINE_CLASS_QUERY(Root)
 882   DEFINE_CLASS_QUERY(SafePoint)
 883   DEFINE_CLASS_QUERY(SafePointScalarObject)
 884   DEFINE_CLASS_QUERY(Start)
 885   DEFINE_CLASS_QUERY(Store)
 886   DEFINE_CLASS_QUERY(Sub)
 887   DEFINE_CLASS_QUERY(Type)
 888   DEFINE_CLASS_QUERY(ValueType)
 889   DEFINE_CLASS_QUERY(ValueTypeBase)
 890   DEFINE_CLASS_QUERY(ValueTypePtr)
 891   DEFINE_CLASS_QUERY(Vector)
 892   DEFINE_CLASS_QUERY(LoadVector)
 893   DEFINE_CLASS_QUERY(StoreVector)
 894   DEFINE_CLASS_QUERY(Unlock)
 895 
 896   #undef DEFINE_CLASS_QUERY
 897 
 898   // duplicate of is_MachSpillCopy()
 899   bool is_SpillCopy () const {
 900     return ((_class_id & ClassMask_MachSpillCopy) == Class_MachSpillCopy);
 901   }
 902 
 903   bool is_Con () const { return (_flags & Flag_is_Con) != 0; }
 904   // The data node which is safe to leave in dead loop during IGVN optimization.
 905   bool is_dead_loop_safe() const {
 906     return is_Phi() || (is_Proj() && in(0) == NULL) ||
 907            ((_flags & (Flag_is_dead_loop_safe | Flag_is_Con)) != 0 &&
 908             (!is_Proj() || !in(0)->is_Allocate()));
 909   }
 910 
 911   // is_Copy() returns copied edge index (0 or 1)
 912   uint is_Copy() const { return (_flags & Flag_is_Copy); }
 913 
 914   virtual bool is_CFG() const { return false; }
 915 
 916   // If this node is control-dependent on a test, can it be
 917   // rerouted to a dominating equivalent test?  This is usually
 918   // true of non-CFG nodes, but can be false for operations which
 919   // depend for their correct sequencing on more than one test.
 920   // (In that case, hoisting to a dominating test may silently
 921   // skip some other important test.)
 922   virtual bool depends_only_on_test() const { assert(!is_CFG(), ""); return true; };
 923 
 924   // When building basic blocks, I need to have a notion of block beginning
 925   // Nodes, next block selector Nodes (block enders), and next block
 926   // projections.  These calls need to work on their machine equivalents.  The
 927   // Ideal beginning Nodes are RootNode, RegionNode and StartNode.
 928   bool is_block_start() const {
 929     if ( is_Region() )
 930       return this == (const Node*)in(0);
 931     else
 932       return is_Start();
 933   }
 934 
 935   // The Ideal control projection Nodes are IfTrue/IfFalse, JumpProjNode, Root,
 936   // Goto and Return.  This call also returns the block ending Node.
 937   virtual const Node *is_block_proj() const;
 938 
 939   // The node is a "macro" node which needs to be expanded before matching
 940   bool is_macro() const { return (_flags & Flag_is_macro) != 0; }
 941   // The node is expensive: the best control is set during loop opts
 942   bool is_expensive() const { return (_flags & Flag_is_expensive) != 0 && in(0) != NULL; }
 943 
 944   // An arithmetic node which accumulates a data in a loop.
 945   // It must have the loop's phi as input and provide a def to the phi.
 946   bool is_reduction() const { return (_flags & Flag_is_reduction) != 0; }
 947 
 948   // The node is a CountedLoopEnd with a mask annotation so as to emit a restore context
 949   bool has_vector_mask_set() const { return (_flags & Flag_has_vector_mask_set) != 0; }
 950 
 951   // Used in lcm to mark nodes that have scheduled
 952   bool is_scheduled() const { return (_flags & Flag_is_scheduled) != 0; }
 953 
 954 //----------------- Optimization
 955 
 956   // Get the worst-case Type output for this Node.
 957   virtual const class Type *bottom_type() const;
 958 
 959   // If we find a better type for a node, try to record it permanently.
 960   // Return true if this node actually changed.
 961   // Be sure to do the hash_delete game in the "rehash" variant.
 962   void raise_bottom_type(const Type* new_type);
 963 
 964   // Get the address type with which this node uses and/or defs memory,
 965   // or NULL if none.  The address type is conservatively wide.
 966   // Returns non-null for calls, membars, loads, stores, etc.
 967   // Returns TypePtr::BOTTOM if the node touches memory "broadly".
 968   virtual const class TypePtr *adr_type() const { return NULL; }
 969 
 970   // Return an existing node which computes the same function as this node.
 971   // The optimistic combined algorithm requires this to return a Node which
 972   // is a small number of steps away (e.g., one of my inputs).
 973   virtual Node* Identity(PhaseGVN* phase);
 974 
 975   // Return the set of values this Node can take on at runtime.
 976   virtual const Type* Value(PhaseGVN* phase) const;
 977 
 978   // Return a node which is more "ideal" than the current node.
 979   // The invariants on this call are subtle.  If in doubt, read the
 980   // treatise in node.cpp above the default implemention AND TEST WITH
 981   // +VerifyIterativeGVN!
 982   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 983 
 984   // Some nodes have specific Ideal subgraph transformations only if they are
 985   // unique users of specific nodes. Such nodes should be put on IGVN worklist
 986   // for the transformations to happen.
 987   bool has_special_unique_user() const;
 988 
 989   // Skip Proj and CatchProj nodes chains. Check for Null and Top.
 990   Node* find_exact_control(Node* ctrl);
 991 
 992   // Check if 'this' node dominates or equal to 'sub'.
 993   bool dominates(Node* sub, Node_List &nlist);
 994 
 995 protected:
 996   bool remove_dead_region(PhaseGVN *phase, bool can_reshape);
 997 public:
 998 
 999   // See if there is valid pipeline info
1000   static  const Pipeline *pipeline_class();
1001   virtual const Pipeline *pipeline() const;
1002 
1003   // Compute the latency from the def to this instruction of the ith input node
1004   uint latency(uint i);
1005 
1006   // Hash & compare functions, for pessimistic value numbering
1007 
1008   // If the hash function returns the special sentinel value NO_HASH,
1009   // the node is guaranteed never to compare equal to any other node.
1010   // If we accidentally generate a hash with value NO_HASH the node
1011   // won't go into the table and we'll lose a little optimization.
1012   static const uint NO_HASH = 0;
1013   virtual uint hash() const;
1014   virtual bool cmp( const Node &n ) const;
1015 
1016   // Operation appears to be iteratively computed (such as an induction variable)
1017   // It is possible for this operation to return false for a loop-varying
1018   // value, if it appears (by local graph inspection) to be computed by a simple conditional.
1019   bool is_iteratively_computed();
1020 
1021   // Determine if a node is a counted loop induction variable.
1022   // NOTE: The method is defined in "loopnode.cpp".
1023   bool is_cloop_ind_var() const;
1024 
1025   // Return a node with opcode "opc" and same inputs as "this" if one can
1026   // be found; Otherwise return NULL;
1027   Node* find_similar(int opc);
1028 
1029   // Return the unique control out if only one. Null if none or more than one.
1030   Node* unique_ctrl_out() const;
1031 
1032   // Set control or add control as precedence edge
1033   void ensure_control_or_add_prec(Node* c);
1034 
1035 //----------------- Code Generation
1036 
1037   // Ideal register class for Matching.  Zero means unmatched instruction
1038   // (these are cloned instead of converted to machine nodes).
1039   virtual uint ideal_reg() const;
1040 
1041   static const uint NotAMachineReg;   // must be > max. machine register
1042 
1043   // Do we Match on this edge index or not?  Generally false for Control
1044   // and true for everything else.  Weird for calls & returns.
1045   virtual uint match_edge(uint idx) const;
1046 
1047   // Register class output is returned in
1048   virtual const RegMask &out_RegMask() const;
1049   // Register class input is expected in
1050   virtual const RegMask &in_RegMask(uint) const;
1051   // Should we clone rather than spill this instruction?
1052   bool rematerialize() const;
1053 
1054   // Return JVM State Object if this Node carries debug info, or NULL otherwise
1055   virtual JVMState* jvms() const;
1056 
1057   // Print as assembly
1058   virtual void format( PhaseRegAlloc *, outputStream* st = tty ) const;
1059   // Emit bytes starting at parameter 'ptr'
1060   // Bump 'ptr' by the number of output bytes
1061   virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const;
1062   // Size of instruction in bytes
1063   virtual uint size(PhaseRegAlloc *ra_) const;
1064 
1065   // Convenience function to extract an integer constant from a node.
1066   // If it is not an integer constant (either Con, CastII, or Mach),
1067   // return value_if_unknown.
1068   jint find_int_con(jint value_if_unknown) const {
1069     const TypeInt* t = find_int_type();
1070     return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
1071   }
1072   // Return the constant, knowing it is an integer constant already
1073   jint get_int() const {
1074     const TypeInt* t = find_int_type();
1075     guarantee(t != NULL, "must be con");
1076     return t->get_con();
1077   }
1078   // Here's where the work is done.  Can produce non-constant int types too.
1079   const TypeInt* find_int_type() const;
1080 
1081   // Same thing for long (and intptr_t, via type.hpp):
1082   jlong get_long() const {
1083     const TypeLong* t = find_long_type();
1084     guarantee(t != NULL, "must be con");
1085     return t->get_con();
1086   }
1087   jlong find_long_con(jint value_if_unknown) const {
1088     const TypeLong* t = find_long_type();
1089     return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
1090   }
1091   const TypeLong* find_long_type() const;
1092 
1093   const TypePtr* get_ptr_type() const;
1094 
1095   // These guys are called by code generated by ADLC:
1096   intptr_t get_ptr() const;
1097   intptr_t get_narrowcon() const;
1098   jdouble getd() const;
1099   jfloat getf() const;
1100 
1101   // Nodes which are pinned into basic blocks
1102   virtual bool pinned() const { return false; }
1103 
1104   // Nodes which use memory without consuming it, hence need antidependences
1105   // More specifically, needs_anti_dependence_check returns true iff the node
1106   // (a) does a load, and (b) does not perform a store (except perhaps to a
1107   // stack slot or some other unaliased location).
1108   bool needs_anti_dependence_check() const;
1109 
1110   // Return which operand this instruction may cisc-spill. In other words,
1111   // return operand position that can convert from reg to memory access
1112   virtual int cisc_operand() const { return AdlcVMDeps::Not_cisc_spillable; }
1113   bool is_cisc_alternate() const { return (_flags & Flag_is_cisc_alternate) != 0; }
1114 
1115 //----------------- Graph walking
1116 public:
1117   // Walk and apply member functions recursively.
1118   // Supplied (this) pointer is root.
1119   void walk(NFunc pre, NFunc post, void *env);
1120   static void nop(Node &, void*); // Dummy empty function
1121   static void packregion( Node &n, void* );
1122 private:
1123   void walk_(NFunc pre, NFunc post, void *env, VectorSet &visited);
1124 
1125 //----------------- Printing, etc
1126 public:
1127 #ifndef PRODUCT
1128   Node* find(int idx) const;         // Search the graph for the given idx.
1129   Node* find_ctrl(int idx) const;    // Search control ancestors for the given idx.
1130   void dump() const { dump("\n"); }  // Print this node.
1131   void dump(const char* suffix, bool mark = false, outputStream *st = tty) const; // Print this node.
1132   void dump(int depth) const;        // Print this node, recursively to depth d
1133   void dump_ctrl(int depth) const;   // Print control nodes, to depth d
1134   void dump_comp() const;            // Print this node in compact representation.
1135   // Print this node in compact representation.
1136   void dump_comp(const char* suffix, outputStream *st = tty) const;
1137   virtual void dump_req(outputStream *st = tty) const;    // Print required-edge info
1138   virtual void dump_prec(outputStream *st = tty) const;   // Print precedence-edge info
1139   virtual void dump_out(outputStream *st = tty) const;    // Print the output edge info
1140   virtual void dump_spec(outputStream *st) const {};      // Print per-node info
1141   // Print compact per-node info
1142   virtual void dump_compact_spec(outputStream *st) const { dump_spec(st); }
1143   void dump_related() const;             // Print related nodes (depends on node at hand).
1144   // Print related nodes up to given depths for input and output nodes.
1145   void dump_related(uint d_in, uint d_out) const;
1146   void dump_related_compact() const;     // Print related nodes in compact representation.
1147   // Collect related nodes.
1148   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
1149   // Collect nodes starting from this node, explicitly including/excluding control and data links.
1150   void collect_nodes(GrowableArray<Node*> *ns, int d, bool ctrl, bool data) const;
1151 
1152   // Node collectors, to be used in implementations of Node::rel().
1153   // Collect the entire data input graph. Include control inputs if requested.
1154   void collect_nodes_in_all_data(GrowableArray<Node*> *ns, bool ctrl) const;
1155   // Collect the entire control input graph. Include data inputs if requested.
1156   void collect_nodes_in_all_ctrl(GrowableArray<Node*> *ns, bool data) const;
1157   // Collect the entire output graph until hitting and including control nodes.
1158   void collect_nodes_out_all_ctrl_boundary(GrowableArray<Node*> *ns) const;
1159 
1160   void verify_edges(Unique_Node_List &visited); // Verify bi-directional edges
1161   void verify() const;               // Check Def-Use info for my subgraph
1162   static void verify_recur(const Node *n, int verify_depth, VectorSet &old_space, VectorSet &new_space);
1163 
1164   // This call defines a class-unique string used to identify class instances
1165   virtual const char *Name() const;
1166 
1167   void dump_format(PhaseRegAlloc *ra) const; // debug access to MachNode::format(...)
1168   // RegMask Print Functions
1169   void dump_in_regmask(int idx) { in_RegMask(idx).dump(); }
1170   void dump_out_regmask() { out_RegMask().dump(); }
1171   static bool in_dump() { return Compile::current()->_in_dump_cnt > 0; }
1172   void fast_dump() const {
1173     tty->print("%4d: %-17s", _idx, Name());
1174     for (uint i = 0; i < len(); i++)
1175       if (in(i))
1176         tty->print(" %4d", in(i)->_idx);
1177       else
1178         tty->print(" NULL");
1179     tty->print("\n");
1180   }
1181 #endif
1182 #ifdef ASSERT
1183   void verify_construction();
1184   bool verify_jvms(const JVMState* jvms) const;
1185   int  _debug_idx;                     // Unique value assigned to every node.
1186   int   debug_idx() const              { return _debug_idx; }
1187   void  set_debug_idx( int debug_idx ) { _debug_idx = debug_idx; }
1188 
1189   Node* _debug_orig;                   // Original version of this, if any.
1190   Node*  debug_orig() const            { return _debug_orig; }
1191   void   set_debug_orig(Node* orig);   // _debug_orig = orig
1192 
1193   int        _hash_lock;               // Barrier to modifications of nodes in the hash table
1194   void  enter_hash_lock() { ++_hash_lock; assert(_hash_lock < 99, "in too many hash tables?"); }
1195   void   exit_hash_lock() { --_hash_lock; assert(_hash_lock >= 0, "mispaired hash locks"); }
1196 
1197   static void init_NodeProperty();
1198 
1199   #if OPTO_DU_ITERATOR_ASSERT
1200   const Node* _last_del;               // The last deleted node.
1201   uint        _del_tick;               // Bumped when a deletion happens..
1202   #endif
1203 #endif
1204 };
1205 
1206 
1207 #ifndef PRODUCT
1208 
1209 // Used in debugging code to avoid walking across dead or uninitialized edges.
1210 inline bool NotANode(const Node* n) {
1211   if (n == NULL)                   return true;
1212   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
1213   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
1214   return false;
1215 }
1216 
1217 #endif
1218 
1219 
1220 //-----------------------------------------------------------------------------
1221 // Iterators over DU info, and associated Node functions.
1222 
1223 #if OPTO_DU_ITERATOR_ASSERT
1224 
1225 // Common code for assertion checking on DU iterators.
1226 class DUIterator_Common {
1227 #ifdef ASSERT
1228  protected:
1229   bool         _vdui;               // cached value of VerifyDUIterators
1230   const Node*  _node;               // the node containing the _out array
1231   uint         _outcnt;             // cached node->_outcnt
1232   uint         _del_tick;           // cached node->_del_tick
1233   Node*        _last;               // last value produced by the iterator
1234 
1235   void sample(const Node* node);    // used by c'tor to set up for verifies
1236   void verify(const Node* node, bool at_end_ok = false);
1237   void verify_resync();
1238   void reset(const DUIterator_Common& that);
1239 
1240 // The VDUI_ONLY macro protects code conditionalized on VerifyDUIterators
1241   #define I_VDUI_ONLY(i,x) { if ((i)._vdui) { x; } }
1242 #else
1243   #define I_VDUI_ONLY(i,x) { }
1244 #endif //ASSERT
1245 };
1246 
1247 #define VDUI_ONLY(x)     I_VDUI_ONLY(*this, x)
1248 
1249 // Default DU iterator.  Allows appends onto the out array.
1250 // Allows deletion from the out array only at the current point.
1251 // Usage:
1252 //  for (DUIterator i = x->outs(); x->has_out(i); i++) {
1253 //    Node* y = x->out(i);
1254 //    ...
1255 //  }
1256 // Compiles in product mode to a unsigned integer index, which indexes
1257 // onto a repeatedly reloaded base pointer of x->_out.  The loop predicate
1258 // also reloads x->_outcnt.  If you delete, you must perform "--i" just
1259 // before continuing the loop.  You must delete only the last-produced
1260 // edge.  You must delete only a single copy of the last-produced edge,
1261 // or else you must delete all copies at once (the first time the edge
1262 // is produced by the iterator).
1263 class DUIterator : public DUIterator_Common {
1264   friend class Node;
1265 
1266   // This is the index which provides the product-mode behavior.
1267   // Whatever the product-mode version of the system does to the
1268   // DUI index is done to this index.  All other fields in
1269   // this class are used only for assertion checking.
1270   uint         _idx;
1271 
1272   #ifdef ASSERT
1273   uint         _refresh_tick;    // Records the refresh activity.
1274 
1275   void sample(const Node* node); // Initialize _refresh_tick etc.
1276   void verify(const Node* node, bool at_end_ok = false);
1277   void verify_increment();       // Verify an increment operation.
1278   void verify_resync();          // Verify that we can back up over a deletion.
1279   void verify_finish();          // Verify that the loop terminated properly.
1280   void refresh();                // Resample verification info.
1281   void reset(const DUIterator& that);  // Resample after assignment.
1282   #endif
1283 
1284   DUIterator(const Node* node, int dummy_to_avoid_conversion)
1285     { _idx = 0;                         debug_only(sample(node)); }
1286 
1287  public:
1288   // initialize to garbage; clear _vdui to disable asserts
1289   DUIterator()
1290     { /*initialize to garbage*/         debug_only(_vdui = false); }
1291 
1292   void operator++(int dummy_to_specify_postfix_op)
1293     { _idx++;                           VDUI_ONLY(verify_increment()); }
1294 
1295   void operator--()
1296     { VDUI_ONLY(verify_resync());       --_idx; }
1297 
1298   ~DUIterator()
1299     { VDUI_ONLY(verify_finish()); }
1300 
1301   void operator=(const DUIterator& that)
1302     { _idx = that._idx;                 debug_only(reset(that)); }
1303 };
1304 
1305 DUIterator Node::outs() const
1306   { return DUIterator(this, 0); }
1307 DUIterator& Node::refresh_out_pos(DUIterator& i) const
1308   { I_VDUI_ONLY(i, i.refresh());        return i; }
1309 bool Node::has_out(DUIterator& i) const
1310   { I_VDUI_ONLY(i, i.verify(this,true));return i._idx < _outcnt; }
1311 Node*    Node::out(DUIterator& i) const
1312   { I_VDUI_ONLY(i, i.verify(this));     return debug_only(i._last=) _out[i._idx]; }
1313 
1314 
1315 // Faster DU iterator.  Disallows insertions into the out array.
1316 // Allows deletion from the out array only at the current point.
1317 // Usage:
1318 //  for (DUIterator_Fast imax, i = x->fast_outs(imax); i < imax; i++) {
1319 //    Node* y = x->fast_out(i);
1320 //    ...
1321 //  }
1322 // Compiles in product mode to raw Node** pointer arithmetic, with
1323 // no reloading of pointers from the original node x.  If you delete,
1324 // you must perform "--i; --imax" just before continuing the loop.
1325 // If you delete multiple copies of the same edge, you must decrement
1326 // imax, but not i, multiple times:  "--i, imax -= num_edges".
1327 class DUIterator_Fast : public DUIterator_Common {
1328   friend class Node;
1329   friend class DUIterator_Last;
1330 
1331   // This is the pointer which provides the product-mode behavior.
1332   // Whatever the product-mode version of the system does to the
1333   // DUI pointer is done to this pointer.  All other fields in
1334   // this class are used only for assertion checking.
1335   Node**       _outp;
1336 
1337   #ifdef ASSERT
1338   void verify(const Node* node, bool at_end_ok = false);
1339   void verify_limit();
1340   void verify_resync();
1341   void verify_relimit(uint n);
1342   void reset(const DUIterator_Fast& that);
1343   #endif
1344 
1345   // Note:  offset must be signed, since -1 is sometimes passed
1346   DUIterator_Fast(const Node* node, ptrdiff_t offset)
1347     { _outp = node->_out + offset;      debug_only(sample(node)); }
1348 
1349  public:
1350   // initialize to garbage; clear _vdui to disable asserts
1351   DUIterator_Fast()
1352     { /*initialize to garbage*/         debug_only(_vdui = false); }
1353 
1354   void operator++(int dummy_to_specify_postfix_op)
1355     { _outp++;                          VDUI_ONLY(verify(_node, true)); }
1356 
1357   void operator--()
1358     { VDUI_ONLY(verify_resync());       --_outp; }
1359 
1360   void operator-=(uint n)   // applied to the limit only
1361     { _outp -= n;           VDUI_ONLY(verify_relimit(n));  }
1362 
1363   bool operator<(DUIterator_Fast& limit) {
1364     I_VDUI_ONLY(*this, this->verify(_node, true));
1365     I_VDUI_ONLY(limit, limit.verify_limit());
1366     return _outp < limit._outp;
1367   }
1368 
1369   void operator=(const DUIterator_Fast& that)
1370     { _outp = that._outp;               debug_only(reset(that)); }
1371 };
1372 
1373 DUIterator_Fast Node::fast_outs(DUIterator_Fast& imax) const {
1374   // Assign a limit pointer to the reference argument:
1375   imax = DUIterator_Fast(this, (ptrdiff_t)_outcnt);
1376   // Return the base pointer:
1377   return DUIterator_Fast(this, 0);
1378 }
1379 Node* Node::fast_out(DUIterator_Fast& i) const {
1380   I_VDUI_ONLY(i, i.verify(this));
1381   return debug_only(i._last=) *i._outp;
1382 }
1383 
1384 
1385 // Faster DU iterator.  Requires each successive edge to be removed.
1386 // Does not allow insertion of any edges.
1387 // Usage:
1388 //  for (DUIterator_Last imin, i = x->last_outs(imin); i >= imin; i -= num_edges) {
1389 //    Node* y = x->last_out(i);
1390 //    ...
1391 //  }
1392 // Compiles in product mode to raw Node** pointer arithmetic, with
1393 // no reloading of pointers from the original node x.
1394 class DUIterator_Last : private DUIterator_Fast {
1395   friend class Node;
1396 
1397   #ifdef ASSERT
1398   void verify(const Node* node, bool at_end_ok = false);
1399   void verify_limit();
1400   void verify_step(uint num_edges);
1401   #endif
1402 
1403   // Note:  offset must be signed, since -1 is sometimes passed
1404   DUIterator_Last(const Node* node, ptrdiff_t offset)
1405     : DUIterator_Fast(node, offset) { }
1406 
1407   void operator++(int dummy_to_specify_postfix_op) {} // do not use
1408   void operator<(int)                              {} // do not use
1409 
1410  public:
1411   DUIterator_Last() { }
1412   // initialize to garbage
1413 
1414   void operator--()
1415     { _outp--;              VDUI_ONLY(verify_step(1));  }
1416 
1417   void operator-=(uint n)
1418     { _outp -= n;           VDUI_ONLY(verify_step(n));  }
1419 
1420   bool operator>=(DUIterator_Last& limit) {
1421     I_VDUI_ONLY(*this, this->verify(_node, true));
1422     I_VDUI_ONLY(limit, limit.verify_limit());
1423     return _outp >= limit._outp;
1424   }
1425 
1426   void operator=(const DUIterator_Last& that)
1427     { DUIterator_Fast::operator=(that); }
1428 };
1429 
1430 DUIterator_Last Node::last_outs(DUIterator_Last& imin) const {
1431   // Assign a limit pointer to the reference argument:
1432   imin = DUIterator_Last(this, 0);
1433   // Return the initial pointer:
1434   return DUIterator_Last(this, (ptrdiff_t)_outcnt - 1);
1435 }
1436 Node* Node::last_out(DUIterator_Last& i) const {
1437   I_VDUI_ONLY(i, i.verify(this));
1438   return debug_only(i._last=) *i._outp;
1439 }
1440 
1441 #endif //OPTO_DU_ITERATOR_ASSERT
1442 
1443 #undef I_VDUI_ONLY
1444 #undef VDUI_ONLY
1445 
1446 // An Iterator that truly follows the iterator pattern.  Doesn't
1447 // support deletion but could be made to.
1448 //
1449 //   for (SimpleDUIterator i(n); i.has_next(); i.next()) {
1450 //     Node* m = i.get();
1451 //
1452 class SimpleDUIterator : public StackObj {
1453  private:
1454   Node* node;
1455   DUIterator_Fast i;
1456   DUIterator_Fast imax;
1457  public:
1458   SimpleDUIterator(Node* n): node(n), i(n->fast_outs(imax)) {}
1459   bool has_next() { return i < imax; }
1460   void next() { i++; }
1461   Node* get() { return node->fast_out(i); }
1462 };
1463 
1464 
1465 //-----------------------------------------------------------------------------
1466 // Map dense integer indices to Nodes.  Uses classic doubling-array trick.
1467 // Abstractly provides an infinite array of Node*'s, initialized to NULL.
1468 // Note that the constructor just zeros things, and since I use Arena
1469 // allocation I do not need a destructor to reclaim storage.
1470 class Node_Array : public ResourceObj {
1471   friend class VMStructs;
1472 protected:
1473   Arena *_a;                    // Arena to allocate in
1474   uint   _max;
1475   Node **_nodes;
1476   void   grow( uint i );        // Grow array node to fit
1477 public:
1478   Node_Array(Arena *a) : _a(a), _max(OptoNodeListSize) {
1479     _nodes = NEW_ARENA_ARRAY( a, Node *, OptoNodeListSize );
1480     for( int i = 0; i < OptoNodeListSize; i++ ) {
1481       _nodes[i] = NULL;
1482     }
1483   }
1484 
1485   Node_Array(Node_Array *na) : _a(na->_a), _max(na->_max), _nodes(na->_nodes) {}
1486   Node *operator[] ( uint i ) const // Lookup, or NULL for not mapped
1487   { return (i<_max) ? _nodes[i] : (Node*)NULL; }
1488   Node *at( uint i ) const { assert(i<_max,"oob"); return _nodes[i]; }
1489   Node **adr() { return _nodes; }
1490   // Extend the mapping: index i maps to Node *n.
1491   void map( uint i, Node *n ) { if( i>=_max ) grow(i); _nodes[i] = n; }
1492   void insert( uint i, Node *n );
1493   void remove( uint i );        // Remove, preserving order
1494   void sort( C_sort_func_t func);
1495   void reset( Arena *new_a );   // Zap mapping to empty; reclaim storage
1496   void clear();                 // Set all entries to NULL, keep storage
1497   uint Size() const { return _max; }
1498   void dump() const;
1499 };
1500 
1501 class Node_List : public Node_Array {
1502   friend class VMStructs;
1503   uint _cnt;
1504 public:
1505   Node_List() : Node_Array(Thread::current()->resource_area()), _cnt(0) {}
1506   Node_List(Arena *a) : Node_Array(a), _cnt(0) {}
1507   bool contains(const Node* n) const {
1508     for (uint e = 0; e < size(); e++) {
1509       if (at(e) == n) return true;
1510     }
1511     return false;
1512   }
1513   void insert( uint i, Node *n ) { Node_Array::insert(i,n); _cnt++; }
1514   void remove( uint i ) { Node_Array::remove(i); _cnt--; }
1515   void push( Node *b ) { map(_cnt++,b); }
1516   void yank( Node *n );         // Find and remove
1517   Node *pop() { return _nodes[--_cnt]; }
1518   Node *rpop() { Node *b = _nodes[0]; _nodes[0]=_nodes[--_cnt]; return b;}
1519   void clear() { _cnt = 0; Node_Array::clear(); } // retain storage
1520   uint size() const { return _cnt; }
1521   void dump() const;
1522   void dump_simple() const;
1523 };
1524 
1525 //------------------------------Unique_Node_List-------------------------------
1526 class Unique_Node_List : public Node_List {
1527   friend class VMStructs;
1528   VectorSet _in_worklist;
1529   uint _clock_index;            // Index in list where to pop from next
1530 public:
1531   Unique_Node_List() : Node_List(), _in_worklist(Thread::current()->resource_area()), _clock_index(0) {}
1532   Unique_Node_List(Arena *a) : Node_List(a), _in_worklist(a), _clock_index(0) {}
1533 
1534   void remove( Node *n );
1535   bool member( Node *n ) { return _in_worklist.test(n->_idx) != 0; }
1536   VectorSet &member_set(){ return _in_worklist; }
1537 
1538   void push( Node *b ) {
1539     if( !_in_worklist.test_set(b->_idx) )
1540       Node_List::push(b);
1541   }
1542   Node *pop() {
1543     if( _clock_index >= size() ) _clock_index = 0;
1544     Node *b = at(_clock_index);
1545     map( _clock_index, Node_List::pop());
1546     if (size() != 0) _clock_index++; // Always start from 0
1547     _in_worklist >>= b->_idx;
1548     return b;
1549   }
1550   Node *remove( uint i ) {
1551     Node *b = Node_List::at(i);
1552     _in_worklist >>= b->_idx;
1553     map(i,Node_List::pop());
1554     return b;
1555   }
1556   void yank( Node *n ) { _in_worklist >>= n->_idx; Node_List::yank(n); }
1557   void  clear() {
1558     _in_worklist.Clear();        // Discards storage but grows automatically
1559     Node_List::clear();
1560     _clock_index = 0;
1561   }
1562 
1563   // Used after parsing to remove useless nodes before Iterative GVN
1564   void remove_useless_nodes(VectorSet &useful);
1565 
1566 #ifndef PRODUCT
1567   void print_set() const { _in_worklist.print(); }
1568 #endif
1569 };
1570 
1571 // Inline definition of Compile::record_for_igvn must be deferred to this point.
1572 inline void Compile::record_for_igvn(Node* n) {
1573   _for_igvn->push(n);
1574 }
1575 
1576 //------------------------------Node_Stack-------------------------------------
1577 class Node_Stack {
1578   friend class VMStructs;
1579 protected:
1580   struct INode {
1581     Node *node; // Processed node
1582     uint  indx; // Index of next node's child
1583   };
1584   INode *_inode_top; // tos, stack grows up
1585   INode *_inode_max; // End of _inodes == _inodes + _max
1586   INode *_inodes;    // Array storage for the stack
1587   Arena *_a;         // Arena to allocate in
1588   void grow();
1589 public:
1590   Node_Stack(int size) {
1591     size_t max = (size > OptoNodeListSize) ? size : OptoNodeListSize;
1592     _a = Thread::current()->resource_area();
1593     _inodes = NEW_ARENA_ARRAY( _a, INode, max );
1594     _inode_max = _inodes + max;
1595     _inode_top = _inodes - 1; // stack is empty
1596   }
1597 
1598   Node_Stack(Arena *a, int size) : _a(a) {
1599     size_t max = (size > OptoNodeListSize) ? size : OptoNodeListSize;
1600     _inodes = NEW_ARENA_ARRAY( _a, INode, max );
1601     _inode_max = _inodes + max;
1602     _inode_top = _inodes - 1; // stack is empty
1603   }
1604 
1605   void pop() {
1606     assert(_inode_top >= _inodes, "node stack underflow");
1607     --_inode_top;
1608   }
1609   void push(Node *n, uint i) {
1610     ++_inode_top;
1611     if (_inode_top >= _inode_max) grow();
1612     INode *top = _inode_top; // optimization
1613     top->node = n;
1614     top->indx = i;
1615   }
1616   Node *node() const {
1617     return _inode_top->node;
1618   }
1619   Node* node_at(uint i) const {
1620     assert(_inodes + i <= _inode_top, "in range");
1621     return _inodes[i].node;
1622   }
1623   uint index() const {
1624     return _inode_top->indx;
1625   }
1626   uint index_at(uint i) const {
1627     assert(_inodes + i <= _inode_top, "in range");
1628     return _inodes[i].indx;
1629   }
1630   void set_node(Node *n) {
1631     _inode_top->node = n;
1632   }
1633   void set_index(uint i) {
1634     _inode_top->indx = i;
1635   }
1636   uint size_max() const { return (uint)pointer_delta(_inode_max, _inodes,  sizeof(INode)); } // Max size
1637   uint size() const { return (uint)pointer_delta((_inode_top+1), _inodes,  sizeof(INode)); } // Current size
1638   bool is_nonempty() const { return (_inode_top >= _inodes); }
1639   bool is_empty() const { return (_inode_top < _inodes); }
1640   void clear() { _inode_top = _inodes - 1; } // retain storage
1641 
1642   // Node_Stack is used to map nodes.
1643   Node* find(uint idx) const;
1644 };
1645 
1646 
1647 //-----------------------------Node_Notes--------------------------------------
1648 // Debugging or profiling annotations loosely and sparsely associated
1649 // with some nodes.  See Compile::node_notes_at for the accessor.
1650 class Node_Notes {
1651   friend class VMStructs;
1652   JVMState* _jvms;
1653 
1654 public:
1655   Node_Notes(JVMState* jvms = NULL) {
1656     _jvms = jvms;
1657   }
1658 
1659   JVMState* jvms()            { return _jvms; }
1660   void  set_jvms(JVMState* x) {        _jvms = x; }
1661 
1662   // True if there is nothing here.
1663   bool is_clear() {
1664     return (_jvms == NULL);
1665   }
1666 
1667   // Make there be nothing here.
1668   void clear() {
1669     _jvms = NULL;
1670   }
1671 
1672   // Make a new, clean node notes.
1673   static Node_Notes* make(Compile* C) {
1674     Node_Notes* nn = NEW_ARENA_ARRAY(C->comp_arena(), Node_Notes, 1);
1675     nn->clear();
1676     return nn;
1677   }
1678 
1679   Node_Notes* clone(Compile* C) {
1680     Node_Notes* nn = NEW_ARENA_ARRAY(C->comp_arena(), Node_Notes, 1);
1681     (*nn) = (*this);
1682     return nn;
1683   }
1684 
1685   // Absorb any information from source.
1686   bool update_from(Node_Notes* source) {
1687     bool changed = false;
1688     if (source != NULL) {
1689       if (source->jvms() != NULL) {
1690         set_jvms(source->jvms());
1691         changed = true;
1692       }
1693     }
1694     return changed;
1695   }
1696 };
1697 
1698 // Inlined accessors for Compile::node_nodes that require the preceding class:
1699 inline Node_Notes*
1700 Compile::locate_node_notes(GrowableArray<Node_Notes*>* arr,
1701                            int idx, bool can_grow) {
1702   assert(idx >= 0, "oob");
1703   int block_idx = (idx >> _log2_node_notes_block_size);
1704   int grow_by = (block_idx - (arr == NULL? 0: arr->length()));
1705   if (grow_by >= 0) {
1706     if (!can_grow) return NULL;
1707     grow_node_notes(arr, grow_by + 1);
1708   }
1709   if (arr == NULL) return NULL;
1710   // (Every element of arr is a sub-array of length _node_notes_block_size.)
1711   return arr->at(block_idx) + (idx & (_node_notes_block_size-1));
1712 }
1713 
1714 inline bool
1715 Compile::set_node_notes_at(int idx, Node_Notes* value) {
1716   if (value == NULL || value->is_clear())
1717     return false;  // nothing to write => write nothing
1718   Node_Notes* loc = locate_node_notes(_node_note_array, idx, true);
1719   assert(loc != NULL, "");
1720   return loc->update_from(value);
1721 }
1722 
1723 
1724 //------------------------------TypeNode---------------------------------------
1725 // Node with a Type constant.
1726 class TypeNode : public Node {
1727 protected:
1728   virtual uint hash() const;    // Check the type
1729   virtual bool cmp( const Node &n ) const;
1730   virtual uint size_of() const; // Size is bigger
1731   const Type* const _type;
1732 public:
1733   void set_type(const Type* t) {
1734     assert(t != NULL, "sanity");
1735     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
1736     *(const Type**)&_type = t;   // cast away const-ness
1737     // If this node is in the hash table, make sure it doesn't need a rehash.
1738     assert(check_hash == NO_HASH || check_hash == hash(), "type change must preserve hash code");
1739   }
1740   const Type* type() const { assert(_type != NULL, "sanity"); return _type; };
1741   TypeNode( const Type *t, uint required ) : Node(required), _type(t) {
1742     init_class_id(Class_Type);
1743   }
1744   virtual const Type* Value(PhaseGVN* phase) const;
1745   virtual const Type *bottom_type() const;
1746   virtual       uint  ideal_reg() const;
1747 #ifndef PRODUCT
1748   virtual void dump_spec(outputStream *st) const;
1749   virtual void dump_compact_spec(outputStream *st) const;
1750 #endif
1751 };
1752 
1753 #endif // SHARE_OPTO_NODE_HPP