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