1 /*
   2  * Copyright (c) 1997, 2016, 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.
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  24 
  25 #ifndef SHARE_VM_OPTO_NODE_HPP
  26 #define SHARE_VM_OPTO_NODE_HPP
  27 
  28 #include "libadt/vectset.hpp"
  29 #include "opto/compile.hpp"
  30 #include "opto/type.hpp"
  31 
  32 // Portions of code courtesy of Clifford Click
  33 
  34 // Optimization - Graph Style
  35 
  36 
  37 class AbstractLockNode;
  38 class AddNode;
  39 class AddPNode;
  40 class AliasInfo;
  41 class AllocateArrayNode;
  42 class AllocateNode;
  43 class ArrayCopyNode;
  44 class Block;
  45 class BoolNode;
  46 class BoxLockNode;
  47 class CMoveNode;
  48 class CallDynamicJavaNode;
  49 class CallJavaNode;
  50 class CallLeafNode;
  51 class CallNode;
  52 class CallRuntimeNode;
  53 class CallStaticJavaNode;
  54 class CatchNode;
  55 class CatchProjNode;
  56 class CheckCastPPNode;
  57 class ClearArrayNode;
  58 class CmpNode;
  59 class CodeBuffer;
  60 class ConstraintCastNode;
  61 class ConNode;
  62 class CountedLoopNode;
  63 class CountedLoopEndNode;
  64 class DecodeNarrowPtrNode;
  65 class DecodeNNode;
  66 class DecodeNKlassNode;
  67 class EncodeNarrowPtrNode;
  68 class EncodePNode;
  69 class EncodePKlassNode;
  70 class FastLockNode;
  71 class FastUnlockNode;
  72 class IfNode;
  73 class IfFalseNode;
  74 class IfTrueNode;
  75 class InitializeNode;
  76 class JVMState;
  77 class JumpNode;
  78 class JumpProjNode;
  79 class LoadNode;
  80 class LoadStoreNode;
  81 class LockNode;
  82 class LoopNode;
  83 class MachBranchNode;
  84 class MachCallDynamicJavaNode;
  85 class MachCallJavaNode;
  86 class MachCallLeafNode;
  87 class MachCallNode;
  88 class MachCallRuntimeNode;
  89 class MachCallStaticJavaNode;
  90 class MachConstantBaseNode;
  91 class MachConstantNode;
  92 class MachGotoNode;
  93 class MachIfNode;
  94 class MachNode;
  95 class MachNullCheckNode;
  96 class MachProjNode;
  97 class MachReturnNode;
  98 class MachSafePointNode;
  99 class MachSpillCopyNode;
 100 class MachTempNode;
 101 class MachMergeNode;
 102 class Matcher;
 103 class MemBarNode;
 104 class MemBarStoreStoreNode;
 105 class MemNode;
 106 class MergeMemNode;
 107 class MulNode;
 108 class MultiNode;
 109 class MultiBranchNode;
 110 class NeverBranchNode;
 111 class Node;
 112 class Node_Array;
 113 class Node_List;
 114 class Node_Stack;
 115 class NullCheckNode;
 116 class OopMap;
 117 class ParmNode;
 118 class PCTableNode;
 119 class PhaseCCP;
 120 class PhaseGVN;
 121 class PhaseIterGVN;
 122 class PhaseRegAlloc;
 123 class PhaseTransform;
 124 class PhaseValues;
 125 class PhiNode;
 126 class Pipeline;
 127 class ProjNode;
 128 class RangeCheckNode;
 129 class RegMask;
 130 class RegionNode;
 131 class RootNode;
 132 class SafePointNode;
 133 class SafePointScalarObjectNode;
 134 class StartNode;
 135 class State;
 136 class StoreNode;
 137 class SubNode;
 138 class Type;
 139 class TypeNode;
 140 class UnlockNode;
 141 class VectorNode;
 142 class LoadVectorNode;
 143 class StoreVectorNode;
 144 class VectorSet;
 145 typedef void (*NFunc)(Node&,void*);
 146 extern "C" {
 147   typedef int (*C_sort_func_t)(const void *, const void *);
 148 }
 149 
 150 // The type of all node counts and indexes.
 151 // It must hold at least 16 bits, but must also be fast to load and store.
 152 // This type, if less than 32 bits, could limit the number of possible nodes.
 153 // (To make this type platform-specific, move to globalDefinitions_xxx.hpp.)
 154 typedef unsigned int node_idx_t;
 155 
 156 
 157 #ifndef OPTO_DU_ITERATOR_ASSERT
 158 #ifdef ASSERT
 159 #define OPTO_DU_ITERATOR_ASSERT 1
 160 #else
 161 #define OPTO_DU_ITERATOR_ASSERT 0
 162 #endif
 163 #endif //OPTO_DU_ITERATOR_ASSERT
 164 
 165 #if OPTO_DU_ITERATOR_ASSERT
 166 class DUIterator;
 167 class DUIterator_Fast;
 168 class DUIterator_Last;
 169 #else
 170 typedef uint   DUIterator;
 171 typedef Node** DUIterator_Fast;
 172 typedef Node** DUIterator_Last;
 173 #endif
 174 
 175 // Node Sentinel
 176 #define NodeSentinel (Node*)-1
 177 
 178 // Unknown count frequency
 179 #define COUNT_UNKNOWN (-1.0f)
 180 
 181 //------------------------------Node-------------------------------------------
 182 // Nodes define actions in the program.  They create values, which have types.
 183 // They are both vertices in a directed graph and program primitives.  Nodes
 184 // are labeled; the label is the "opcode", the primitive function in the lambda
 185 // calculus sense that gives meaning to the Node.  Node inputs are ordered (so
 186 // that "a-b" is different from "b-a").  The inputs to a Node are the inputs to
 187 // the Node's function.  These inputs also define a Type equation for the Node.
 188 // Solving these Type equations amounts to doing dataflow analysis.
 189 // Control and data are uniformly represented in the graph.  Finally, Nodes
 190 // have a unique dense integer index which is used to index into side arrays
 191 // whenever I have phase-specific information.
 192 
 193 class Node {
 194   friend class VMStructs;
 195 
 196   // Lots of restrictions on cloning Nodes
 197   Node(const Node&);            // not defined; linker error to use these
 198   Node &operator=(const Node &rhs);
 199 
 200 public:
 201   friend class Compile;
 202   #if OPTO_DU_ITERATOR_ASSERT
 203   friend class DUIterator_Common;
 204   friend class DUIterator;
 205   friend class DUIterator_Fast;
 206   friend class DUIterator_Last;
 207   #endif
 208 
 209   // Because Nodes come and go, I define an Arena of Node structures to pull
 210   // from.  This should allow fast access to node creation & deletion.  This
 211   // field is a local cache of a value defined in some "program fragment" for
 212   // which these Nodes are just a part of.
 213 
 214   inline void* operator new(size_t x) throw() {
 215     Compile* C = Compile::current();
 216     Node* n = (Node*)C->node_arena()->Amalloc_D(x);
 217 #ifdef ASSERT
 218     n->_in = (Node**)n; // magic cookie for assertion check
 219 #endif
 220     return (void*)n;
 221   }
 222 
 223   // Delete is a NOP
 224   void operator delete( void *ptr ) {}
 225   // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 226   void destruct();
 227 
 228   // Create a new Node.  Required is the number is of inputs required for
 229   // semantic correctness.
 230   Node( uint required );
 231 
 232   // Create a new Node with given input edges.
 233   // This version requires use of the "edge-count" new.
 234   // E.g.  new (C,3) FooNode( C, NULL, left, right );
 235   Node( Node *n0 );
 236   Node( Node *n0, Node *n1 );
 237   Node( Node *n0, Node *n1, Node *n2 );
 238   Node( Node *n0, Node *n1, Node *n2, Node *n3 );
 239   Node( Node *n0, Node *n1, Node *n2, Node *n3, Node *n4 );
 240   Node( Node *n0, Node *n1, Node *n2, Node *n3, Node *n4, Node *n5 );
 241   Node( Node *n0, Node *n1, Node *n2, Node *n3,
 242             Node *n4, Node *n5, Node *n6 );
 243 
 244   // Clone an inherited Node given only the base Node type.
 245   Node* clone() const;
 246 
 247   // Clone a Node, immediately supplying one or two new edges.
 248   // The first and second arguments, if non-null, replace in(1) and in(2),
 249   // respectively.
 250   Node* clone_with_data_edge(Node* in1, Node* in2 = NULL) const {
 251     Node* nn = clone();
 252     if (in1 != NULL)  nn->set_req(1, in1);
 253     if (in2 != NULL)  nn->set_req(2, in2);
 254     return nn;
 255   }
 256 
 257 private:
 258   // Shared setup for the above constructors.
 259   // Handles all interactions with Compile::current.
 260   // Puts initial values in all Node fields except _idx.
 261   // Returns the initial value for _idx, which cannot
 262   // be initialized by assignment.
 263   inline int Init(int req);
 264 
 265 //----------------- input edge handling
 266 protected:
 267   friend class PhaseCFG;        // Access to address of _in array elements
 268   Node **_in;                   // Array of use-def references to Nodes
 269   Node **_out;                  // Array of def-use references to Nodes
 270 
 271   // Input edges are split into two categories.  Required edges are required
 272   // for semantic correctness; order is important and NULLs are allowed.
 273   // Precedence edges are used to help determine execution order and are
 274   // added, e.g., for scheduling purposes.  They are unordered and not
 275   // duplicated; they have no embedded NULLs.  Edges from 0 to _cnt-1
 276   // are required, from _cnt to _max-1 are precedence edges.
 277   node_idx_t _cnt;              // Total number of required Node inputs.
 278 
 279   node_idx_t _max;              // Actual length of input array.
 280 
 281   // Output edges are an unordered list of def-use edges which exactly
 282   // correspond to required input edges which point from other nodes
 283   // to this one.  Thus the count of the output edges is the number of
 284   // users of this node.
 285   node_idx_t _outcnt;           // Total number of Node outputs.
 286 
 287   node_idx_t _outmax;           // Actual length of output array.
 288 
 289   // Grow the actual input array to the next larger power-of-2 bigger than len.
 290   void grow( uint len );
 291   // Grow the output array to the next larger power-of-2 bigger than len.
 292   void out_grow( uint len );
 293 
 294  public:
 295   // Each Node is assigned a unique small/dense number.  This number is used
 296   // to index into auxiliary arrays of data and bit vectors.
 297   // The field _idx is declared constant to defend against inadvertent assignments,
 298   // since it is used by clients as a naked field. However, the field's value can be
 299   // changed using the set_idx() method.
 300   //
 301   // The PhaseRenumberLive phase renumbers nodes based on liveness information.
 302   // Therefore, it updates the value of the _idx field. The parse-time _idx is
 303   // preserved in _parse_idx.
 304   const node_idx_t _idx;
 305   DEBUG_ONLY(const node_idx_t _parse_idx;)
 306 
 307   // Get the (read-only) number of input edges
 308   uint req() const { return _cnt; }
 309   uint len() const { return _max; }
 310   // Get the (read-only) number of output edges
 311   uint outcnt() const { return _outcnt; }
 312 
 313 #if OPTO_DU_ITERATOR_ASSERT
 314   // Iterate over the out-edges of this node.  Deletions are illegal.
 315   inline DUIterator outs() const;
 316   // Use this when the out array might have changed to suppress asserts.
 317   inline DUIterator& refresh_out_pos(DUIterator& i) const;
 318   // Does the node have an out at this position?  (Used for iteration.)
 319   inline bool has_out(DUIterator& i) const;
 320   inline Node*    out(DUIterator& i) const;
 321   // Iterate over the out-edges of this node.  All changes are illegal.
 322   inline DUIterator_Fast fast_outs(DUIterator_Fast& max) const;
 323   inline Node*    fast_out(DUIterator_Fast& i) const;
 324   // Iterate over the out-edges of this node, deleting one at a time.
 325   inline DUIterator_Last last_outs(DUIterator_Last& min) const;
 326   inline Node*    last_out(DUIterator_Last& i) const;
 327   // The inline bodies of all these methods are after the iterator definitions.
 328 #else
 329   // Iterate over the out-edges of this node.  Deletions are illegal.
 330   // This iteration uses integral indexes, to decouple from array reallocations.
 331   DUIterator outs() const  { return 0; }
 332   // Use this when the out array might have changed to suppress asserts.
 333   DUIterator refresh_out_pos(DUIterator i) const { return i; }
 334 
 335   // Reference to the i'th output Node.  Error if out of bounds.
 336   Node*    out(DUIterator i) const { assert(i < _outcnt, "oob"); return _out[i]; }
 337   // Does the node have an out at this position?  (Used for iteration.)
 338   bool has_out(DUIterator i) const { return i < _outcnt; }
 339 
 340   // Iterate over the out-edges of this node.  All changes are illegal.
 341   // This iteration uses a pointer internal to the out array.
 342   DUIterator_Fast fast_outs(DUIterator_Fast& max) const {
 343     Node** out = _out;
 344     // Assign a limit pointer to the reference argument:
 345     max = out + (ptrdiff_t)_outcnt;
 346     // Return the base pointer:
 347     return out;
 348   }
 349   Node*    fast_out(DUIterator_Fast i) const  { return *i; }
 350   // Iterate over the out-edges of this node, deleting one at a time.
 351   // This iteration uses a pointer internal to the out array.
 352   DUIterator_Last last_outs(DUIterator_Last& min) const {
 353     Node** out = _out;
 354     // Assign a limit pointer to the reference argument:
 355     min = out;
 356     // Return the pointer to the start of the iteration:
 357     return out + (ptrdiff_t)_outcnt - 1;
 358   }
 359   Node*    last_out(DUIterator_Last i) const  { return *i; }
 360 #endif
 361 
 362   // Reference to the i'th input Node.  Error if out of bounds.
 363   Node* in(uint i) const { assert(i < _max, "oob: i=%d, _max=%d", i, _max); return _in[i]; }
 364   // Reference to the i'th input Node.  NULL if out of bounds.
 365   Node* lookup(uint i) const { return ((i < _max) ? _in[i] : NULL); }
 366   // Reference to the i'th output Node.  Error if out of bounds.
 367   // Use this accessor sparingly.  We are going trying to use iterators instead.
 368   Node* raw_out(uint i) const { assert(i < _outcnt,"oob"); return _out[i]; }
 369   // Return the unique out edge.
 370   Node* unique_out() const { assert(_outcnt==1,"not unique"); return _out[0]; }
 371   // Delete out edge at position 'i' by moving last out edge to position 'i'
 372   void  raw_del_out(uint i) {
 373     assert(i < _outcnt,"oob");
 374     assert(_outcnt > 0,"oob");
 375     #if OPTO_DU_ITERATOR_ASSERT
 376     // Record that a change happened here.
 377     debug_only(_last_del = _out[i]; ++_del_tick);
 378     #endif
 379     _out[i] = _out[--_outcnt];
 380     // Smash the old edge so it can't be used accidentally.
 381     debug_only(_out[_outcnt] = (Node *)(uintptr_t)0xdeadbeef);
 382   }
 383 
 384 #ifdef ASSERT
 385   bool is_dead() const;
 386 #define is_not_dead(n) ((n) == NULL || !VerifyIterativeGVN || !((n)->is_dead()))
 387 #endif
 388   // Check whether node has become unreachable
 389   bool is_unreachable(PhaseIterGVN &igvn) const;
 390 
 391   // Set a required input edge, also updates corresponding output edge
 392   void add_req( Node *n ); // Append a NEW required input
 393   void add_req( Node *n0, Node *n1 ) {
 394     add_req(n0); add_req(n1); }
 395   void add_req( Node *n0, Node *n1, Node *n2 ) {
 396     add_req(n0); add_req(n1); add_req(n2); }
 397   void add_req_batch( Node* n, uint m ); // Append m NEW required inputs (all n).
 398   void del_req( uint idx ); // Delete required edge & compact
 399   void del_req_ordered( uint idx ); // Delete required edge & compact with preserved order
 400   void ins_req( uint i, Node *n ); // Insert a NEW required input
 401   void set_req( uint i, Node *n ) {
 402     assert( is_not_dead(n), "can not use dead node");
 403     assert( i < _cnt, "oob: i=%d, _cnt=%d", i, _cnt);
 404     assert( !VerifyHashTableKeys || _hash_lock == 0,
 405             "remove node from hash table before modifying it");
 406     Node** p = &_in[i];    // cache this._in, across the del_out call
 407     if (*p != NULL)  (*p)->del_out((Node *)this);
 408     (*p) = n;
 409     if (n != NULL)      n->add_out((Node *)this);
 410     Compile::current()->record_modified_node(this);
 411   }
 412   // Light version of set_req() to init inputs after node creation.
 413   void init_req( uint i, Node *n ) {
 414     assert( i == 0 && this == n ||
 415             is_not_dead(n), "can not use dead node");
 416     assert( i < _cnt, "oob");
 417     assert( !VerifyHashTableKeys || _hash_lock == 0,
 418             "remove node from hash table before modifying it");
 419     assert( _in[i] == NULL, "sanity");
 420     _in[i] = n;
 421     if (n != NULL)      n->add_out((Node *)this);
 422     Compile::current()->record_modified_node(this);
 423   }
 424   // Find first occurrence of n among my edges:
 425   int find_edge(Node* n);
 426   int find_prec_edge(Node* n) {
 427     for (uint i = req(); i < len(); i++) {
 428       if (_in[i] == n) return i;
 429       if (_in[i] == NULL) {
 430         DEBUG_ONLY( while ((++i) < len()) assert(_in[i] == NULL, "Gap in prec edges!"); )
 431         break;
 432       }
 433     }
 434     return -1;
 435   }
 436   int replace_edge(Node* old, Node* neww);
 437   int replace_edges_in_range(Node* old, Node* neww, int start, int end);
 438   // NULL out all inputs to eliminate incoming Def-Use edges.
 439   // Return the number of edges between 'n' and 'this'
 440   int  disconnect_inputs(Node *n, Compile *c);
 441 
 442   // Quickly, return true if and only if I am Compile::current()->top().
 443   bool is_top() const {
 444     assert((this == (Node*) Compile::current()->top()) == (_out == NULL), "");
 445     return (_out == NULL);
 446   }
 447   // Reaffirm invariants for is_top.  (Only from Compile::set_cached_top_node.)
 448   void setup_is_top();
 449 
 450   // Strip away casting.  (It is depth-limited.)
 451   Node* uncast() const;
 452   // Return whether two Nodes are equivalent, after stripping casting.
 453   bool eqv_uncast(const Node* n) const {
 454     return (this->uncast() == n->uncast());
 455   }
 456 
 457   // Find out of current node that matches opcode.
 458   Node* find_out_with(int opcode);
 459   // Return true if the current node has an out that matches opcode.
 460   bool has_out_with(int opcode);
 461   // Return true if the current node has an out that matches any of the opcodes.
 462   bool has_out_with(int opcode1, int opcode2, int opcode3, int opcode4);
 463 
 464 private:
 465   static Node* uncast_helper(const Node* n);
 466 
 467   // Add an output edge to the end of the list
 468   void add_out( Node *n ) {
 469     if (is_top())  return;
 470     if( _outcnt == _outmax ) out_grow(_outcnt);
 471     _out[_outcnt++] = n;
 472   }
 473   // Delete an output edge
 474   void del_out( Node *n ) {
 475     if (is_top())  return;
 476     Node** outp = &_out[_outcnt];
 477     // Find and remove n
 478     do {
 479       assert(outp > _out, "Missing Def-Use edge");
 480     } while (*--outp != n);
 481     *outp = _out[--_outcnt];
 482     // Smash the old edge so it can't be used accidentally.
 483     debug_only(_out[_outcnt] = (Node *)(uintptr_t)0xdeadbeef);
 484     // Record that a change happened here.
 485     #if OPTO_DU_ITERATOR_ASSERT
 486     debug_only(_last_del = n; ++_del_tick);
 487     #endif
 488   }
 489   // Close gap after removing edge.
 490   void close_prec_gap_at(uint gap) {
 491     assert(_cnt <= gap && gap < _max, "no valid prec edge");
 492     uint i = gap;
 493     Node *last = NULL;
 494     for (; i < _max-1; ++i) {
 495       Node *next = _in[i+1];
 496       if (next == NULL) break;
 497       last = next;
 498     }
 499     _in[gap] = last; // Move last slot to empty one.
 500     _in[i] = NULL;   // NULL out last slot.
 501   }
 502 
 503 public:
 504   // Globally replace this node by a given new node, updating all uses.
 505   void replace_by(Node* new_node);
 506   // Globally replace this node by a given new node, updating all uses
 507   // and cutting input edges of old node.
 508   void subsume_by(Node* new_node, Compile* c) {
 509     replace_by(new_node);
 510     disconnect_inputs(NULL, c);
 511   }
 512   void set_req_X( uint i, Node *n, PhaseIterGVN *igvn );
 513   // Find the one non-null required input.  RegionNode only
 514   Node *nonnull_req() const;
 515   // Add or remove precedence edges
 516   void add_prec( Node *n );
 517   void rm_prec( uint i );
 518 
 519   // Note: prec(i) will not necessarily point to n if edge already exists.
 520   void set_prec( uint i, Node *n ) {
 521     assert(i < _max, "oob: i=%d, _max=%d", i, _max);
 522     assert(is_not_dead(n), "can not use dead node");
 523     assert(i >= _cnt, "not a precedence edge");
 524     // Avoid spec violation: duplicated prec edge.
 525     if (_in[i] == n) return;
 526     if (n == NULL || find_prec_edge(n) != -1) {
 527       rm_prec(i);
 528       return;
 529     }
 530     if (_in[i] != NULL) _in[i]->del_out((Node *)this);
 531     _in[i] = n;
 532     if (n != NULL) n->add_out((Node *)this);
 533   }
 534 
 535   // Set this node's index, used by cisc_version to replace current node
 536   void set_idx(uint new_idx) {
 537     const node_idx_t* ref = &_idx;
 538     *(node_idx_t*)ref = new_idx;
 539   }
 540   // Swap input edge order.  (Edge indexes i1 and i2 are usually 1 and 2.)
 541   void swap_edges(uint i1, uint i2) {
 542     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
 543     // Def-Use info is unchanged
 544     Node* n1 = in(i1);
 545     Node* n2 = in(i2);
 546     _in[i1] = n2;
 547     _in[i2] = n1;
 548     // If this node is in the hash table, make sure it doesn't need a rehash.
 549     assert(check_hash == NO_HASH || check_hash == hash(), "edge swap must preserve hash code");
 550   }
 551 
 552   // Iterators over input Nodes for a Node X are written as:
 553   // for( i = 0; i < X.req(); i++ ) ... X[i] ...
 554   // NOTE: Required edges can contain embedded NULL pointers.
 555 
 556 //----------------- Other Node Properties
 557 
 558   // Generate class IDs for (some) ideal nodes so that it is possible to determine
 559   // the type of a node using a non-virtual method call (the method is_<Node>() below).
 560   //
 561   // A class ID of an ideal node is a set of bits. In a class ID, a single bit determines
 562   // the type of the node the ID represents; another subset of an ID's bits are reserved
 563   // for the superclasses of the node represented by the ID.
 564   //
 565   // By design, if A is a supertype of B, A.is_B() returns true and B.is_A()
 566   // returns false. A.is_A() returns true.
 567   //
 568   // If two classes, A and B, have the same superclass, a different bit of A's class id
 569   // is reserved for A's type than for B's type. That bit is specified by the third
 570   // parameter in the macro DEFINE_CLASS_ID.
 571   //
 572   // By convention, classes with deeper hierarchy are declared first. Moreover,
 573   // classes with the same hierarchy depth are sorted by usage frequency.
 574   //
 575   // The query method masks the bits to cut off bits of subclasses and then compares
 576   // the result with the class id (see the macro DEFINE_CLASS_QUERY below).
 577   //
 578   //  Class_MachCall=30, ClassMask_MachCall=31
 579   // 12               8               4               0
 580   //  0   0   0   0   0   0   0   0   1   1   1   1   0
 581   //                                  |   |   |   |
 582   //                                  |   |   |   Bit_Mach=2
 583   //                                  |   |   Bit_MachReturn=4
 584   //                                  |   Bit_MachSafePoint=8
 585   //                                  Bit_MachCall=16
 586   //
 587   //  Class_CountedLoop=56, ClassMask_CountedLoop=63
 588   // 12               8               4               0
 589   //  0   0   0   0   0   0   0   1   1   1   0   0   0
 590   //                              |   |   |
 591   //                              |   |   Bit_Region=8
 592   //                              |   Bit_Loop=16
 593   //                              Bit_CountedLoop=32
 594 
 595   #define DEFINE_CLASS_ID(cl, supcl, subn) \
 596   Bit_##cl = (Class_##supcl == 0) ? 1 << subn : (Bit_##supcl) << (1 + subn) , \
 597   Class_##cl = Class_##supcl + Bit_##cl , \
 598   ClassMask_##cl = ((Bit_##cl << 1) - 1) ,
 599 
 600   // This enum is used only for C2 ideal and mach nodes with is_<node>() methods
 601   // so that it's values fits into 16 bits.
 602   enum NodeClasses {
 603     Bit_Node   = 0x0000,
 604     Class_Node = 0x0000,
 605     ClassMask_Node = 0xFFFF,
 606 
 607     DEFINE_CLASS_ID(Multi, Node, 0)
 608       DEFINE_CLASS_ID(SafePoint, Multi, 0)
 609         DEFINE_CLASS_ID(Call,      SafePoint, 0)
 610           DEFINE_CLASS_ID(CallJava,         Call, 0)
 611             DEFINE_CLASS_ID(CallStaticJava,   CallJava, 0)
 612             DEFINE_CLASS_ID(CallDynamicJava,  CallJava, 1)
 613           DEFINE_CLASS_ID(CallRuntime,      Call, 1)
 614             DEFINE_CLASS_ID(CallLeaf,         CallRuntime, 0)
 615           DEFINE_CLASS_ID(Allocate,         Call, 2)
 616             DEFINE_CLASS_ID(AllocateArray,    Allocate, 0)
 617           DEFINE_CLASS_ID(AbstractLock,     Call, 3)
 618             DEFINE_CLASS_ID(Lock,             AbstractLock, 0)
 619             DEFINE_CLASS_ID(Unlock,           AbstractLock, 1)
 620           DEFINE_CLASS_ID(ArrayCopy,        Call, 4)
 621       DEFINE_CLASS_ID(MultiBranch, Multi, 1)
 622         DEFINE_CLASS_ID(PCTable,     MultiBranch, 0)
 623           DEFINE_CLASS_ID(Catch,       PCTable, 0)
 624           DEFINE_CLASS_ID(Jump,        PCTable, 1)
 625         DEFINE_CLASS_ID(If,          MultiBranch, 1)
 626           DEFINE_CLASS_ID(CountedLoopEnd, If, 0)
 627           DEFINE_CLASS_ID(RangeCheck, If, 1)
 628         DEFINE_CLASS_ID(NeverBranch, MultiBranch, 2)
 629       DEFINE_CLASS_ID(Start,       Multi, 2)
 630       DEFINE_CLASS_ID(MemBar,      Multi, 3)
 631         DEFINE_CLASS_ID(Initialize,       MemBar, 0)
 632         DEFINE_CLASS_ID(MemBarStoreStore, MemBar, 1)
 633 
 634     DEFINE_CLASS_ID(Mach,  Node, 1)
 635       DEFINE_CLASS_ID(MachReturn, Mach, 0)
 636         DEFINE_CLASS_ID(MachSafePoint, MachReturn, 0)
 637           DEFINE_CLASS_ID(MachCall, MachSafePoint, 0)
 638             DEFINE_CLASS_ID(MachCallJava,         MachCall, 0)
 639               DEFINE_CLASS_ID(MachCallStaticJava,   MachCallJava, 0)
 640               DEFINE_CLASS_ID(MachCallDynamicJava,  MachCallJava, 1)
 641             DEFINE_CLASS_ID(MachCallRuntime,      MachCall, 1)
 642               DEFINE_CLASS_ID(MachCallLeaf,         MachCallRuntime, 0)
 643       DEFINE_CLASS_ID(MachBranch, Mach, 1)
 644         DEFINE_CLASS_ID(MachIf,         MachBranch, 0)
 645         DEFINE_CLASS_ID(MachGoto,       MachBranch, 1)
 646         DEFINE_CLASS_ID(MachNullCheck,  MachBranch, 2)
 647       DEFINE_CLASS_ID(MachSpillCopy,    Mach, 2)
 648       DEFINE_CLASS_ID(MachTemp,         Mach, 3)
 649       DEFINE_CLASS_ID(MachConstantBase, Mach, 4)
 650       DEFINE_CLASS_ID(MachConstant,     Mach, 5)
 651       DEFINE_CLASS_ID(MachMerge,        Mach, 6)
 652 
 653     DEFINE_CLASS_ID(Type,  Node, 2)
 654       DEFINE_CLASS_ID(Phi,   Type, 0)
 655       DEFINE_CLASS_ID(ConstraintCast, Type, 1)
 656       DEFINE_CLASS_ID(CheckCastPP, Type, 2)
 657       DEFINE_CLASS_ID(CMove, Type, 3)
 658       DEFINE_CLASS_ID(SafePointScalarObject, Type, 4)
 659       DEFINE_CLASS_ID(DecodeNarrowPtr, Type, 5)
 660         DEFINE_CLASS_ID(DecodeN, DecodeNarrowPtr, 0)
 661         DEFINE_CLASS_ID(DecodeNKlass, DecodeNarrowPtr, 1)
 662       DEFINE_CLASS_ID(EncodeNarrowPtr, Type, 6)
 663         DEFINE_CLASS_ID(EncodeP, EncodeNarrowPtr, 0)
 664         DEFINE_CLASS_ID(EncodePKlass, EncodeNarrowPtr, 1)
 665 
 666     DEFINE_CLASS_ID(Proj,  Node, 3)
 667       DEFINE_CLASS_ID(CatchProj, Proj, 0)
 668       DEFINE_CLASS_ID(JumpProj,  Proj, 1)
 669       DEFINE_CLASS_ID(IfTrue,    Proj, 2)
 670       DEFINE_CLASS_ID(IfFalse,   Proj, 3)
 671       DEFINE_CLASS_ID(Parm,      Proj, 4)
 672       DEFINE_CLASS_ID(MachProj,  Proj, 5)
 673 
 674     DEFINE_CLASS_ID(Mem,   Node, 4)
 675       DEFINE_CLASS_ID(Load,  Mem, 0)
 676         DEFINE_CLASS_ID(LoadVector,  Load, 0)
 677       DEFINE_CLASS_ID(Store, Mem, 1)
 678         DEFINE_CLASS_ID(StoreVector, Store, 0)
 679       DEFINE_CLASS_ID(LoadStore, Mem, 2)
 680 
 681     DEFINE_CLASS_ID(Region, Node, 5)
 682       DEFINE_CLASS_ID(Loop, Region, 0)
 683         DEFINE_CLASS_ID(Root,        Loop, 0)
 684         DEFINE_CLASS_ID(CountedLoop, Loop, 1)
 685 
 686     DEFINE_CLASS_ID(Sub,   Node, 6)
 687       DEFINE_CLASS_ID(Cmp,   Sub, 0)
 688         DEFINE_CLASS_ID(FastLock,   Cmp, 0)
 689         DEFINE_CLASS_ID(FastUnlock, Cmp, 1)
 690 
 691     DEFINE_CLASS_ID(MergeMem, Node, 7)
 692     DEFINE_CLASS_ID(Bool,     Node, 8)
 693     DEFINE_CLASS_ID(AddP,     Node, 9)
 694     DEFINE_CLASS_ID(BoxLock,  Node, 10)
 695     DEFINE_CLASS_ID(Add,      Node, 11)
 696     DEFINE_CLASS_ID(Mul,      Node, 12)
 697     DEFINE_CLASS_ID(Vector,   Node, 13)
 698     DEFINE_CLASS_ID(ClearArray, Node, 14)
 699 
 700     _max_classes  = ClassMask_ClearArray
 701   };
 702   #undef DEFINE_CLASS_ID
 703 
 704   // Flags are sorted by usage frequency.
 705   enum NodeFlags {
 706     Flag_is_Copy                     = 0x01, // should be first bit to avoid shift
 707     Flag_rematerialize               = Flag_is_Copy << 1,
 708     Flag_needs_anti_dependence_check = Flag_rematerialize << 1,
 709     Flag_is_macro                    = Flag_needs_anti_dependence_check << 1,
 710     Flag_is_Con                      = Flag_is_macro << 1,
 711     Flag_is_cisc_alternate           = Flag_is_Con << 1,
 712     Flag_is_dead_loop_safe           = Flag_is_cisc_alternate << 1,
 713     Flag_may_be_short_branch         = Flag_is_dead_loop_safe << 1,
 714     Flag_avoid_back_to_back_before   = Flag_may_be_short_branch << 1,
 715     Flag_avoid_back_to_back_after    = Flag_avoid_back_to_back_before << 1,
 716     Flag_has_call                    = Flag_avoid_back_to_back_after << 1,
 717     Flag_is_reduction                = Flag_has_call << 1,
 718     Flag_is_scheduled                = Flag_is_reduction,
 719     Flag_is_expensive                = Flag_is_scheduled << 1,
 720     _max_flags = (Flag_is_expensive << 1) - 1 // allow flags combination
 721   };
 722 
 723 private:
 724   jushort _class_id;
 725   jushort _flags;
 726 
 727 protected:
 728   // These methods should be called from constructors only.
 729   void init_class_id(jushort c) {
 730     assert(c <= _max_classes, "invalid node class");
 731     _class_id = c; // cast out const
 732   }
 733   void init_flags(jushort fl) {
 734     assert(fl <= _max_flags, "invalid node flag");
 735     _flags |= fl;
 736   }
 737   void clear_flag(jushort fl) {
 738     assert(fl <= _max_flags, "invalid node flag");
 739     _flags &= ~fl;
 740   }
 741 
 742 public:
 743   const jushort class_id() const { return _class_id; }
 744 
 745   const jushort flags() const { return _flags; }
 746 
 747   void add_flag(jushort fl) { init_flags(fl); }
 748 
 749   void remove_flag(jushort fl) { clear_flag(fl); }
 750 
 751   // Return a dense integer opcode number
 752   virtual int Opcode() const;
 753 
 754   // Virtual inherited Node size
 755   virtual uint size_of() const;
 756 
 757   // Other interesting Node properties
 758   #define DEFINE_CLASS_QUERY(type)                           \
 759   bool is_##type() const {                                   \
 760     return ((_class_id & ClassMask_##type) == Class_##type); \
 761   }                                                          \
 762   type##Node *as_##type() const {                            \
 763     assert(is_##type(), "invalid node class");               \
 764     return (type##Node*)this;                                \
 765   }                                                          \
 766   type##Node* isa_##type() const {                           \
 767     return (is_##type()) ? as_##type() : NULL;               \
 768   }
 769 
 770   DEFINE_CLASS_QUERY(AbstractLock)
 771   DEFINE_CLASS_QUERY(Add)
 772   DEFINE_CLASS_QUERY(AddP)
 773   DEFINE_CLASS_QUERY(Allocate)
 774   DEFINE_CLASS_QUERY(AllocateArray)
 775   DEFINE_CLASS_QUERY(ArrayCopy)
 776   DEFINE_CLASS_QUERY(Bool)
 777   DEFINE_CLASS_QUERY(BoxLock)
 778   DEFINE_CLASS_QUERY(Call)
 779   DEFINE_CLASS_QUERY(CallDynamicJava)
 780   DEFINE_CLASS_QUERY(CallJava)
 781   DEFINE_CLASS_QUERY(CallLeaf)
 782   DEFINE_CLASS_QUERY(CallRuntime)
 783   DEFINE_CLASS_QUERY(CallStaticJava)
 784   DEFINE_CLASS_QUERY(Catch)
 785   DEFINE_CLASS_QUERY(CatchProj)
 786   DEFINE_CLASS_QUERY(CheckCastPP)
 787   DEFINE_CLASS_QUERY(ConstraintCast)
 788   DEFINE_CLASS_QUERY(ClearArray)
 789   DEFINE_CLASS_QUERY(CMove)
 790   DEFINE_CLASS_QUERY(Cmp)
 791   DEFINE_CLASS_QUERY(CountedLoop)
 792   DEFINE_CLASS_QUERY(CountedLoopEnd)
 793   DEFINE_CLASS_QUERY(DecodeNarrowPtr)
 794   DEFINE_CLASS_QUERY(DecodeN)
 795   DEFINE_CLASS_QUERY(DecodeNKlass)
 796   DEFINE_CLASS_QUERY(EncodeNarrowPtr)
 797   DEFINE_CLASS_QUERY(EncodeP)
 798   DEFINE_CLASS_QUERY(EncodePKlass)
 799   DEFINE_CLASS_QUERY(FastLock)
 800   DEFINE_CLASS_QUERY(FastUnlock)
 801   DEFINE_CLASS_QUERY(If)
 802   DEFINE_CLASS_QUERY(RangeCheck)
 803   DEFINE_CLASS_QUERY(IfFalse)
 804   DEFINE_CLASS_QUERY(IfTrue)
 805   DEFINE_CLASS_QUERY(Initialize)
 806   DEFINE_CLASS_QUERY(Jump)
 807   DEFINE_CLASS_QUERY(JumpProj)
 808   DEFINE_CLASS_QUERY(Load)
 809   DEFINE_CLASS_QUERY(LoadStore)
 810   DEFINE_CLASS_QUERY(Lock)
 811   DEFINE_CLASS_QUERY(Loop)
 812   DEFINE_CLASS_QUERY(Mach)
 813   DEFINE_CLASS_QUERY(MachBranch)
 814   DEFINE_CLASS_QUERY(MachCall)
 815   DEFINE_CLASS_QUERY(MachCallDynamicJava)
 816   DEFINE_CLASS_QUERY(MachCallJava)
 817   DEFINE_CLASS_QUERY(MachCallLeaf)
 818   DEFINE_CLASS_QUERY(MachCallRuntime)
 819   DEFINE_CLASS_QUERY(MachCallStaticJava)
 820   DEFINE_CLASS_QUERY(MachConstantBase)
 821   DEFINE_CLASS_QUERY(MachConstant)
 822   DEFINE_CLASS_QUERY(MachGoto)
 823   DEFINE_CLASS_QUERY(MachIf)
 824   DEFINE_CLASS_QUERY(MachNullCheck)
 825   DEFINE_CLASS_QUERY(MachProj)
 826   DEFINE_CLASS_QUERY(MachReturn)
 827   DEFINE_CLASS_QUERY(MachSafePoint)
 828   DEFINE_CLASS_QUERY(MachSpillCopy)
 829   DEFINE_CLASS_QUERY(MachTemp)
 830   DEFINE_CLASS_QUERY(MachMerge)
 831   DEFINE_CLASS_QUERY(Mem)
 832   DEFINE_CLASS_QUERY(MemBar)
 833   DEFINE_CLASS_QUERY(MemBarStoreStore)
 834   DEFINE_CLASS_QUERY(MergeMem)
 835   DEFINE_CLASS_QUERY(Mul)
 836   DEFINE_CLASS_QUERY(Multi)
 837   DEFINE_CLASS_QUERY(MultiBranch)
 838   DEFINE_CLASS_QUERY(Parm)
 839   DEFINE_CLASS_QUERY(PCTable)
 840   DEFINE_CLASS_QUERY(Phi)
 841   DEFINE_CLASS_QUERY(Proj)
 842   DEFINE_CLASS_QUERY(Region)
 843   DEFINE_CLASS_QUERY(Root)
 844   DEFINE_CLASS_QUERY(SafePoint)
 845   DEFINE_CLASS_QUERY(SafePointScalarObject)
 846   DEFINE_CLASS_QUERY(Start)
 847   DEFINE_CLASS_QUERY(Store)
 848   DEFINE_CLASS_QUERY(Sub)
 849   DEFINE_CLASS_QUERY(Type)
 850   DEFINE_CLASS_QUERY(Vector)
 851   DEFINE_CLASS_QUERY(LoadVector)
 852   DEFINE_CLASS_QUERY(StoreVector)
 853   DEFINE_CLASS_QUERY(Unlock)
 854 
 855   #undef DEFINE_CLASS_QUERY
 856 
 857   // duplicate of is_MachSpillCopy()
 858   bool is_SpillCopy () const {
 859     return ((_class_id & ClassMask_MachSpillCopy) == Class_MachSpillCopy);
 860   }
 861 
 862   bool is_Con () const { return (_flags & Flag_is_Con) != 0; }
 863   // The data node which is safe to leave in dead loop during IGVN optimization.
 864   bool is_dead_loop_safe() const {
 865     return is_Phi() || (is_Proj() && in(0) == NULL) ||
 866            ((_flags & (Flag_is_dead_loop_safe | Flag_is_Con)) != 0 &&
 867             (!is_Proj() || !in(0)->is_Allocate()));
 868   }
 869 
 870   // is_Copy() returns copied edge index (0 or 1)
 871   uint is_Copy() const { return (_flags & Flag_is_Copy); }
 872 
 873   virtual bool is_CFG() const { return false; }
 874 
 875   // If this node is control-dependent on a test, can it be
 876   // rerouted to a dominating equivalent test?  This is usually
 877   // true of non-CFG nodes, but can be false for operations which
 878   // depend for their correct sequencing on more than one test.
 879   // (In that case, hoisting to a dominating test may silently
 880   // skip some other important test.)
 881   virtual bool depends_only_on_test() const { assert(!is_CFG(), ""); return true; };
 882 
 883   // When building basic blocks, I need to have a notion of block beginning
 884   // Nodes, next block selector Nodes (block enders), and next block
 885   // projections.  These calls need to work on their machine equivalents.  The
 886   // Ideal beginning Nodes are RootNode, RegionNode and StartNode.
 887   bool is_block_start() const {
 888     if ( is_Region() )
 889       return this == (const Node*)in(0);
 890     else
 891       return is_Start();
 892   }
 893 
 894   // The Ideal control projection Nodes are IfTrue/IfFalse, JumpProjNode, Root,
 895   // Goto and Return.  This call also returns the block ending Node.
 896   virtual const Node *is_block_proj() const;
 897 
 898   // The node is a "macro" node which needs to be expanded before matching
 899   bool is_macro() const { return (_flags & Flag_is_macro) != 0; }
 900   // The node is expensive: the best control is set during loop opts
 901   bool is_expensive() const { return (_flags & Flag_is_expensive) != 0 && in(0) != NULL; }
 902 
 903   // An arithmetic node which accumulates a data in a loop.
 904   // It must have the loop's phi as input and provide a def to the phi.
 905   bool is_reduction() const { return (_flags & Flag_is_reduction) != 0; }
 906 
 907   // Used in lcm to mark nodes that have scheduled
 908   bool is_scheduled() const { return (_flags & Flag_is_scheduled) != 0; }
 909 
 910 //----------------- Optimization
 911 
 912   // Get the worst-case Type output for this Node.
 913   virtual const class Type *bottom_type() const;
 914 
 915   // If we find a better type for a node, try to record it permanently.
 916   // Return true if this node actually changed.
 917   // Be sure to do the hash_delete game in the "rehash" variant.
 918   void raise_bottom_type(const Type* new_type);
 919 
 920   // Get the address type with which this node uses and/or defs memory,
 921   // or NULL if none.  The address type is conservatively wide.
 922   // Returns non-null for calls, membars, loads, stores, etc.
 923   // Returns TypePtr::BOTTOM if the node touches memory "broadly".
 924   virtual const class TypePtr *adr_type() const { return NULL; }
 925 
 926   // Return an existing node which computes the same function as this node.
 927   // The optimistic combined algorithm requires this to return a Node which
 928   // is a small number of steps away (e.g., one of my inputs).
 929   virtual Node* Identity(PhaseGVN* phase);
 930 
 931   // Return the set of values this Node can take on at runtime.
 932   virtual const Type* Value(PhaseGVN* phase) const;
 933 
 934   // Return a node which is more "ideal" than the current node.
 935   // The invariants on this call are subtle.  If in doubt, read the
 936   // treatise in node.cpp above the default implemention AND TEST WITH
 937   // +VerifyIterativeGVN!
 938   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 939 
 940   // Some nodes have specific Ideal subgraph transformations only if they are
 941   // unique users of specific nodes. Such nodes should be put on IGVN worklist
 942   // for the transformations to happen.
 943   bool has_special_unique_user() const;
 944 
 945   // Skip Proj and CatchProj nodes chains. Check for Null and Top.
 946   Node* find_exact_control(Node* ctrl);
 947 
 948   // Check if 'this' node dominates or equal to 'sub'.
 949   bool dominates(Node* sub, Node_List &nlist);
 950 
 951 protected:
 952   bool remove_dead_region(PhaseGVN *phase, bool can_reshape);
 953 public:
 954 
 955   // See if there is valid pipeline info
 956   static  const Pipeline *pipeline_class();
 957   virtual const Pipeline *pipeline() const;
 958 
 959   // Compute the latency from the def to this instruction of the ith input node
 960   uint latency(uint i);
 961 
 962   // Hash & compare functions, for pessimistic value numbering
 963 
 964   // If the hash function returns the special sentinel value NO_HASH,
 965   // the node is guaranteed never to compare equal to any other node.
 966   // If we accidentally generate a hash with value NO_HASH the node
 967   // won't go into the table and we'll lose a little optimization.
 968   enum { NO_HASH = 0 };
 969   virtual uint hash() const;
 970   virtual uint cmp( const Node &n ) const;
 971 
 972   // Operation appears to be iteratively computed (such as an induction variable)
 973   // It is possible for this operation to return false for a loop-varying
 974   // value, if it appears (by local graph inspection) to be computed by a simple conditional.
 975   bool is_iteratively_computed();
 976 
 977   // Determine if a node is Counted loop induction variable.
 978   // The method is defined in loopnode.cpp.
 979   const Node* is_loop_iv() const;
 980 
 981   // Return a node with opcode "opc" and same inputs as "this" if one can
 982   // be found; Otherwise return NULL;
 983   Node* find_similar(int opc);
 984 
 985   // Return the unique control out if only one. Null if none or more than one.
 986   Node* unique_ctrl_out() const;
 987 
 988   // Set control or add control as precedence edge
 989   void ensure_control_or_add_prec(Node* c);
 990 
 991 //----------------- Code Generation
 992 
 993   // Ideal register class for Matching.  Zero means unmatched instruction
 994   // (these are cloned instead of converted to machine nodes).
 995   virtual uint ideal_reg() const;
 996 
 997   static const uint NotAMachineReg;   // must be > max. machine register
 998 
 999   // Do we Match on this edge index or not?  Generally false for Control
1000   // and true for everything else.  Weird for calls & returns.
1001   virtual uint match_edge(uint idx) const;
1002 
1003   // Register class output is returned in
1004   virtual const RegMask &out_RegMask() const;
1005   // Register class input is expected in
1006   virtual const RegMask &in_RegMask(uint) const;
1007   // Should we clone rather than spill this instruction?
1008   bool rematerialize() const;
1009 
1010   // Return JVM State Object if this Node carries debug info, or NULL otherwise
1011   virtual JVMState* jvms() const;
1012 
1013   // Print as assembly
1014   virtual void format( PhaseRegAlloc *, outputStream* st = tty ) const;
1015   // Emit bytes starting at parameter 'ptr'
1016   // Bump 'ptr' by the number of output bytes
1017   virtual void emit(CodeBuffer &cbuf, PhaseRegAlloc *ra_) const;
1018   // Size of instruction in bytes
1019   virtual uint size(PhaseRegAlloc *ra_) const;
1020 
1021   // Convenience function to extract an integer constant from a node.
1022   // If it is not an integer constant (either Con, CastII, or Mach),
1023   // return value_if_unknown.
1024   jint find_int_con(jint value_if_unknown) const {
1025     const TypeInt* t = find_int_type();
1026     return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
1027   }
1028   // Return the constant, knowing it is an integer constant already
1029   jint get_int() const {
1030     const TypeInt* t = find_int_type();
1031     guarantee(t != NULL, "must be con");
1032     return t->get_con();
1033   }
1034   // Here's where the work is done.  Can produce non-constant int types too.
1035   const TypeInt* find_int_type() const;
1036 
1037   // Same thing for long (and intptr_t, via type.hpp):
1038   jlong get_long() const {
1039     const TypeLong* t = find_long_type();
1040     guarantee(t != NULL, "must be con");
1041     return t->get_con();
1042   }
1043   jlong find_long_con(jint value_if_unknown) const {
1044     const TypeLong* t = find_long_type();
1045     return (t != NULL && t->is_con()) ? t->get_con() : value_if_unknown;
1046   }
1047   const TypeLong* find_long_type() const;
1048 
1049   const TypePtr* get_ptr_type() const;
1050 
1051   // These guys are called by code generated by ADLC:
1052   intptr_t get_ptr() const;
1053   intptr_t get_narrowcon() const;
1054   jdouble getd() const;
1055   jfloat getf() const;
1056 
1057   // Nodes which are pinned into basic blocks
1058   virtual bool pinned() const { return false; }
1059 
1060   // Nodes which use memory without consuming it, hence need antidependences
1061   // More specifically, needs_anti_dependence_check returns true iff the node
1062   // (a) does a load, and (b) does not perform a store (except perhaps to a
1063   // stack slot or some other unaliased location).
1064   bool needs_anti_dependence_check() const;
1065 
1066   // Return which operand this instruction may cisc-spill. In other words,
1067   // return operand position that can convert from reg to memory access
1068   virtual int cisc_operand() const { return AdlcVMDeps::Not_cisc_spillable; }
1069   bool is_cisc_alternate() const { return (_flags & Flag_is_cisc_alternate) != 0; }
1070 
1071 //----------------- Graph walking
1072 public:
1073   // Walk and apply member functions recursively.
1074   // Supplied (this) pointer is root.
1075   void walk(NFunc pre, NFunc post, void *env);
1076   static void nop(Node &, void*); // Dummy empty function
1077   static void packregion( Node &n, void* );
1078 private:
1079   void walk_(NFunc pre, NFunc post, void *env, VectorSet &visited);
1080 
1081 //----------------- Printing, etc
1082 public:
1083 #ifndef PRODUCT
1084   Node* find(int idx) const;         // Search the graph for the given idx.
1085   Node* find_ctrl(int idx) const;    // Search control ancestors for the given idx.
1086   void dump() const { dump("\n"); }  // Print this node.
1087   void dump(const char* suffix, bool mark = false, outputStream *st = tty) const; // Print this node.
1088   void dump(int depth) const;        // Print this node, recursively to depth d
1089   void dump_ctrl(int depth) const;   // Print control nodes, to depth d
1090   void dump_comp() const;            // Print this node in compact representation.
1091   // Print this node in compact representation.
1092   void dump_comp(const char* suffix, outputStream *st = tty) const;
1093   virtual void dump_req(outputStream *st = tty) const;    // Print required-edge info
1094   virtual void dump_prec(outputStream *st = tty) const;   // Print precedence-edge info
1095   virtual void dump_out(outputStream *st = tty) const;    // Print the output edge info
1096   virtual void dump_spec(outputStream *st) const {};      // Print per-node info
1097   // Print compact per-node info
1098   virtual void dump_compact_spec(outputStream *st) const { dump_spec(st); }
1099   void dump_related() const;             // Print related nodes (depends on node at hand).
1100   // Print related nodes up to given depths for input and output nodes.
1101   void dump_related(uint d_in, uint d_out) const;
1102   void dump_related_compact() const;     // Print related nodes in compact representation.
1103   // Collect related nodes.
1104   virtual void related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const;
1105   // Collect nodes starting from this node, explicitly including/excluding control and data links.
1106   void collect_nodes(GrowableArray<Node*> *ns, int d, bool ctrl, bool data) const;
1107 
1108   // Node collectors, to be used in implementations of Node::rel().
1109   // Collect the entire data input graph. Include control inputs if requested.
1110   void collect_nodes_in_all_data(GrowableArray<Node*> *ns, bool ctrl) const;
1111   // Collect the entire control input graph. Include data inputs if requested.
1112   void collect_nodes_in_all_ctrl(GrowableArray<Node*> *ns, bool data) const;
1113   // Collect the entire output graph until hitting and including control nodes.
1114   void collect_nodes_out_all_ctrl_boundary(GrowableArray<Node*> *ns) const;
1115 
1116   void verify_edges(Unique_Node_List &visited); // Verify bi-directional edges
1117   void verify() const;               // Check Def-Use info for my subgraph
1118   static void verify_recur(const Node *n, int verify_depth, VectorSet &old_space, VectorSet &new_space);
1119 
1120   // This call defines a class-unique string used to identify class instances
1121   virtual const char *Name() const;
1122 
1123   void dump_format(PhaseRegAlloc *ra) const; // debug access to MachNode::format(...)
1124   // RegMask Print Functions
1125   void dump_in_regmask(int idx) { in_RegMask(idx).dump(); }
1126   void dump_out_regmask() { out_RegMask().dump(); }
1127   static bool in_dump() { return Compile::current()->_in_dump_cnt > 0; }
1128   void fast_dump() const {
1129     tty->print("%4d: %-17s", _idx, Name());
1130     for (uint i = 0; i < len(); i++)
1131       if (in(i))
1132         tty->print(" %4d", in(i)->_idx);
1133       else
1134         tty->print(" NULL");
1135     tty->print("\n");
1136   }
1137 #endif
1138 #ifdef ASSERT
1139   void verify_construction();
1140   bool verify_jvms(const JVMState* jvms) const;
1141   int  _debug_idx;                     // Unique value assigned to every node.
1142   int   debug_idx() const              { return _debug_idx; }
1143   void  set_debug_idx( int debug_idx ) { _debug_idx = debug_idx; }
1144 
1145   Node* _debug_orig;                   // Original version of this, if any.
1146   Node*  debug_orig() const            { return _debug_orig; }
1147   void   set_debug_orig(Node* orig);   // _debug_orig = orig
1148 
1149   int        _hash_lock;               // Barrier to modifications of nodes in the hash table
1150   void  enter_hash_lock() { ++_hash_lock; assert(_hash_lock < 99, "in too many hash tables?"); }
1151   void   exit_hash_lock() { --_hash_lock; assert(_hash_lock >= 0, "mispaired hash locks"); }
1152 
1153   static void init_NodeProperty();
1154 
1155   #if OPTO_DU_ITERATOR_ASSERT
1156   const Node* _last_del;               // The last deleted node.
1157   uint        _del_tick;               // Bumped when a deletion happens..
1158   #endif
1159 #endif
1160 };
1161 
1162 
1163 #ifndef PRODUCT
1164 
1165 // Used in debugging code to avoid walking across dead or uninitialized edges.
1166 inline bool NotANode(const Node* n) {
1167   if (n == NULL)                   return true;
1168   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
1169   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
1170   return false;
1171 }
1172 
1173 #endif
1174 
1175 
1176 //-----------------------------------------------------------------------------
1177 // Iterators over DU info, and associated Node functions.
1178 
1179 #if OPTO_DU_ITERATOR_ASSERT
1180 
1181 // Common code for assertion checking on DU iterators.
1182 class DUIterator_Common VALUE_OBJ_CLASS_SPEC {
1183 #ifdef ASSERT
1184  protected:
1185   bool         _vdui;               // cached value of VerifyDUIterators
1186   const Node*  _node;               // the node containing the _out array
1187   uint         _outcnt;             // cached node->_outcnt
1188   uint         _del_tick;           // cached node->_del_tick
1189   Node*        _last;               // last value produced by the iterator
1190 
1191   void sample(const Node* node);    // used by c'tor to set up for verifies
1192   void verify(const Node* node, bool at_end_ok = false);
1193   void verify_resync();
1194   void reset(const DUIterator_Common& that);
1195 
1196 // The VDUI_ONLY macro protects code conditionalized on VerifyDUIterators
1197   #define I_VDUI_ONLY(i,x) { if ((i)._vdui) { x; } }
1198 #else
1199   #define I_VDUI_ONLY(i,x) { }
1200 #endif //ASSERT
1201 };
1202 
1203 #define VDUI_ONLY(x)     I_VDUI_ONLY(*this, x)
1204 
1205 // Default DU iterator.  Allows appends onto the out array.
1206 // Allows deletion from the out array only at the current point.
1207 // Usage:
1208 //  for (DUIterator i = x->outs(); x->has_out(i); i++) {
1209 //    Node* y = x->out(i);
1210 //    ...
1211 //  }
1212 // Compiles in product mode to a unsigned integer index, which indexes
1213 // onto a repeatedly reloaded base pointer of x->_out.  The loop predicate
1214 // also reloads x->_outcnt.  If you delete, you must perform "--i" just
1215 // before continuing the loop.  You must delete only the last-produced
1216 // edge.  You must delete only a single copy of the last-produced edge,
1217 // or else you must delete all copies at once (the first time the edge
1218 // is produced by the iterator).
1219 class DUIterator : public DUIterator_Common {
1220   friend class Node;
1221 
1222   // This is the index which provides the product-mode behavior.
1223   // Whatever the product-mode version of the system does to the
1224   // DUI index is done to this index.  All other fields in
1225   // this class are used only for assertion checking.
1226   uint         _idx;
1227 
1228   #ifdef ASSERT
1229   uint         _refresh_tick;    // Records the refresh activity.
1230 
1231   void sample(const Node* node); // Initialize _refresh_tick etc.
1232   void verify(const Node* node, bool at_end_ok = false);
1233   void verify_increment();       // Verify an increment operation.
1234   void verify_resync();          // Verify that we can back up over a deletion.
1235   void verify_finish();          // Verify that the loop terminated properly.
1236   void refresh();                // Resample verification info.
1237   void reset(const DUIterator& that);  // Resample after assignment.
1238   #endif
1239 
1240   DUIterator(const Node* node, int dummy_to_avoid_conversion)
1241     { _idx = 0;                         debug_only(sample(node)); }
1242 
1243  public:
1244   // initialize to garbage; clear _vdui to disable asserts
1245   DUIterator()
1246     { /*initialize to garbage*/         debug_only(_vdui = false); }
1247 
1248   void operator++(int dummy_to_specify_postfix_op)
1249     { _idx++;                           VDUI_ONLY(verify_increment()); }
1250 
1251   void operator--()
1252     { VDUI_ONLY(verify_resync());       --_idx; }
1253 
1254   ~DUIterator()
1255     { VDUI_ONLY(verify_finish()); }
1256 
1257   void operator=(const DUIterator& that)
1258     { _idx = that._idx;                 debug_only(reset(that)); }
1259 };
1260 
1261 DUIterator Node::outs() const
1262   { return DUIterator(this, 0); }
1263 DUIterator& Node::refresh_out_pos(DUIterator& i) const
1264   { I_VDUI_ONLY(i, i.refresh());        return i; }
1265 bool Node::has_out(DUIterator& i) const
1266   { I_VDUI_ONLY(i, i.verify(this,true));return i._idx < _outcnt; }
1267 Node*    Node::out(DUIterator& i) const
1268   { I_VDUI_ONLY(i, i.verify(this));     return debug_only(i._last=) _out[i._idx]; }
1269 
1270 
1271 // Faster DU iterator.  Disallows insertions into the out array.
1272 // Allows deletion from the out array only at the current point.
1273 // Usage:
1274 //  for (DUIterator_Fast imax, i = x->fast_outs(imax); i < imax; i++) {
1275 //    Node* y = x->fast_out(i);
1276 //    ...
1277 //  }
1278 // Compiles in product mode to raw Node** pointer arithmetic, with
1279 // no reloading of pointers from the original node x.  If you delete,
1280 // you must perform "--i; --imax" just before continuing the loop.
1281 // If you delete multiple copies of the same edge, you must decrement
1282 // imax, but not i, multiple times:  "--i, imax -= num_edges".
1283 class DUIterator_Fast : public DUIterator_Common {
1284   friend class Node;
1285   friend class DUIterator_Last;
1286 
1287   // This is the pointer which provides the product-mode behavior.
1288   // Whatever the product-mode version of the system does to the
1289   // DUI pointer is done to this pointer.  All other fields in
1290   // this class are used only for assertion checking.
1291   Node**       _outp;
1292 
1293   #ifdef ASSERT
1294   void verify(const Node* node, bool at_end_ok = false);
1295   void verify_limit();
1296   void verify_resync();
1297   void verify_relimit(uint n);
1298   void reset(const DUIterator_Fast& that);
1299   #endif
1300 
1301   // Note:  offset must be signed, since -1 is sometimes passed
1302   DUIterator_Fast(const Node* node, ptrdiff_t offset)
1303     { _outp = node->_out + offset;      debug_only(sample(node)); }
1304 
1305  public:
1306   // initialize to garbage; clear _vdui to disable asserts
1307   DUIterator_Fast()
1308     { /*initialize to garbage*/         debug_only(_vdui = false); }
1309 
1310   void operator++(int dummy_to_specify_postfix_op)
1311     { _outp++;                          VDUI_ONLY(verify(_node, true)); }
1312 
1313   void operator--()
1314     { VDUI_ONLY(verify_resync());       --_outp; }
1315 
1316   void operator-=(uint n)   // applied to the limit only
1317     { _outp -= n;           VDUI_ONLY(verify_relimit(n));  }
1318 
1319   bool operator<(DUIterator_Fast& limit) {
1320     I_VDUI_ONLY(*this, this->verify(_node, true));
1321     I_VDUI_ONLY(limit, limit.verify_limit());
1322     return _outp < limit._outp;
1323   }
1324 
1325   void operator=(const DUIterator_Fast& that)
1326     { _outp = that._outp;               debug_only(reset(that)); }
1327 };
1328 
1329 DUIterator_Fast Node::fast_outs(DUIterator_Fast& imax) const {
1330   // Assign a limit pointer to the reference argument:
1331   imax = DUIterator_Fast(this, (ptrdiff_t)_outcnt);
1332   // Return the base pointer:
1333   return DUIterator_Fast(this, 0);
1334 }
1335 Node* Node::fast_out(DUIterator_Fast& i) const {
1336   I_VDUI_ONLY(i, i.verify(this));
1337   return debug_only(i._last=) *i._outp;
1338 }
1339 
1340 
1341 // Faster DU iterator.  Requires each successive edge to be removed.
1342 // Does not allow insertion of any edges.
1343 // Usage:
1344 //  for (DUIterator_Last imin, i = x->last_outs(imin); i >= imin; i -= num_edges) {
1345 //    Node* y = x->last_out(i);
1346 //    ...
1347 //  }
1348 // Compiles in product mode to raw Node** pointer arithmetic, with
1349 // no reloading of pointers from the original node x.
1350 class DUIterator_Last : private DUIterator_Fast {
1351   friend class Node;
1352 
1353   #ifdef ASSERT
1354   void verify(const Node* node, bool at_end_ok = false);
1355   void verify_limit();
1356   void verify_step(uint num_edges);
1357   #endif
1358 
1359   // Note:  offset must be signed, since -1 is sometimes passed
1360   DUIterator_Last(const Node* node, ptrdiff_t offset)
1361     : DUIterator_Fast(node, offset) { }
1362 
1363   void operator++(int dummy_to_specify_postfix_op) {} // do not use
1364   void operator<(int)                              {} // do not use
1365 
1366  public:
1367   DUIterator_Last() { }
1368   // initialize to garbage
1369 
1370   void operator--()
1371     { _outp--;              VDUI_ONLY(verify_step(1));  }
1372 
1373   void operator-=(uint n)
1374     { _outp -= n;           VDUI_ONLY(verify_step(n));  }
1375 
1376   bool operator>=(DUIterator_Last& limit) {
1377     I_VDUI_ONLY(*this, this->verify(_node, true));
1378     I_VDUI_ONLY(limit, limit.verify_limit());
1379     return _outp >= limit._outp;
1380   }
1381 
1382   void operator=(const DUIterator_Last& that)
1383     { DUIterator_Fast::operator=(that); }
1384 };
1385 
1386 DUIterator_Last Node::last_outs(DUIterator_Last& imin) const {
1387   // Assign a limit pointer to the reference argument:
1388   imin = DUIterator_Last(this, 0);
1389   // Return the initial pointer:
1390   return DUIterator_Last(this, (ptrdiff_t)_outcnt - 1);
1391 }
1392 Node* Node::last_out(DUIterator_Last& i) const {
1393   I_VDUI_ONLY(i, i.verify(this));
1394   return debug_only(i._last=) *i._outp;
1395 }
1396 
1397 #endif //OPTO_DU_ITERATOR_ASSERT
1398 
1399 #undef I_VDUI_ONLY
1400 #undef VDUI_ONLY
1401 
1402 // An Iterator that truly follows the iterator pattern.  Doesn't
1403 // support deletion but could be made to.
1404 //
1405 //   for (SimpleDUIterator i(n); i.has_next(); i.next()) {
1406 //     Node* m = i.get();
1407 //
1408 class SimpleDUIterator : public StackObj {
1409  private:
1410   Node* node;
1411   DUIterator_Fast i;
1412   DUIterator_Fast imax;
1413  public:
1414   SimpleDUIterator(Node* n): node(n), i(n->fast_outs(imax)) {}
1415   bool has_next() { return i < imax; }
1416   void next() { i++; }
1417   Node* get() { return node->fast_out(i); }
1418 };
1419 
1420 
1421 //-----------------------------------------------------------------------------
1422 // Map dense integer indices to Nodes.  Uses classic doubling-array trick.
1423 // Abstractly provides an infinite array of Node*'s, initialized to NULL.
1424 // Note that the constructor just zeros things, and since I use Arena
1425 // allocation I do not need a destructor to reclaim storage.
1426 class Node_Array : public ResourceObj {
1427   friend class VMStructs;
1428 protected:
1429   Arena *_a;                    // Arena to allocate in
1430   uint   _max;
1431   Node **_nodes;
1432   void   grow( uint i );        // Grow array node to fit
1433 public:
1434   Node_Array(Arena *a) : _a(a), _max(OptoNodeListSize) {
1435     _nodes = NEW_ARENA_ARRAY( a, Node *, OptoNodeListSize );
1436     for( int i = 0; i < OptoNodeListSize; i++ ) {
1437       _nodes[i] = NULL;
1438     }
1439   }
1440 
1441   Node_Array(Node_Array *na) : _a(na->_a), _max(na->_max), _nodes(na->_nodes) {}
1442   Node *operator[] ( uint i ) const // Lookup, or NULL for not mapped
1443   { return (i<_max) ? _nodes[i] : (Node*)NULL; }
1444   Node *at( uint i ) const { assert(i<_max,"oob"); return _nodes[i]; }
1445   Node **adr() { return _nodes; }
1446   // Extend the mapping: index i maps to Node *n.
1447   void map( uint i, Node *n ) { if( i>=_max ) grow(i); _nodes[i] = n; }
1448   void insert( uint i, Node *n );
1449   void remove( uint i );        // Remove, preserving order
1450   void sort( C_sort_func_t func);
1451   void reset( Arena *new_a );   // Zap mapping to empty; reclaim storage
1452   void clear();                 // Set all entries to NULL, keep storage
1453   uint Size() const { return _max; }
1454   void dump() const;
1455 };
1456 
1457 class Node_List : public Node_Array {
1458   friend class VMStructs;
1459   uint _cnt;
1460 public:
1461   Node_List() : Node_Array(Thread::current()->resource_area()), _cnt(0) {}
1462   Node_List(Arena *a) : Node_Array(a), _cnt(0) {}
1463   bool contains(const Node* n) const {
1464     for (uint e = 0; e < size(); e++) {
1465       if (at(e) == n) return true;
1466     }
1467     return false;
1468   }
1469   void insert( uint i, Node *n ) { Node_Array::insert(i,n); _cnt++; }
1470   void remove( uint i ) { Node_Array::remove(i); _cnt--; }
1471   void push( Node *b ) { map(_cnt++,b); }
1472   void yank( Node *n );         // Find and remove
1473   Node *pop() { return _nodes[--_cnt]; }
1474   Node *rpop() { Node *b = _nodes[0]; _nodes[0]=_nodes[--_cnt]; return b;}
1475   void clear() { _cnt = 0; Node_Array::clear(); } // retain storage
1476   uint size() const { return _cnt; }
1477   void dump() const;
1478   void dump_simple() const;
1479 };
1480 
1481 //------------------------------Unique_Node_List-------------------------------
1482 class Unique_Node_List : public Node_List {
1483   friend class VMStructs;
1484   VectorSet _in_worklist;
1485   uint _clock_index;            // Index in list where to pop from next
1486 public:
1487   Unique_Node_List() : Node_List(), _in_worklist(Thread::current()->resource_area()), _clock_index(0) {}
1488   Unique_Node_List(Arena *a) : Node_List(a), _in_worklist(a), _clock_index(0) {}
1489 
1490   void remove( Node *n );
1491   bool member( Node *n ) { return _in_worklist.test(n->_idx) != 0; }
1492   VectorSet &member_set(){ return _in_worklist; }
1493 
1494   void push( Node *b ) {
1495     if( !_in_worklist.test_set(b->_idx) )
1496       Node_List::push(b);
1497   }
1498   Node *pop() {
1499     if( _clock_index >= size() ) _clock_index = 0;
1500     Node *b = at(_clock_index);
1501     map( _clock_index, Node_List::pop());
1502     if (size() != 0) _clock_index++; // Always start from 0
1503     _in_worklist >>= b->_idx;
1504     return b;
1505   }
1506   Node *remove( uint i ) {
1507     Node *b = Node_List::at(i);
1508     _in_worklist >>= b->_idx;
1509     map(i,Node_List::pop());
1510     return b;
1511   }
1512   void yank( Node *n ) { _in_worklist >>= n->_idx; Node_List::yank(n); }
1513   void  clear() {
1514     _in_worklist.Clear();        // Discards storage but grows automatically
1515     Node_List::clear();
1516     _clock_index = 0;
1517   }
1518 
1519   // Used after parsing to remove useless nodes before Iterative GVN
1520   void remove_useless_nodes(VectorSet &useful);
1521 
1522 #ifndef PRODUCT
1523   void print_set() const { _in_worklist.print(); }
1524 #endif
1525 };
1526 
1527 // Inline definition of Compile::record_for_igvn must be deferred to this point.
1528 inline void Compile::record_for_igvn(Node* n) {
1529   _for_igvn->push(n);
1530 }
1531 
1532 //------------------------------Node_Stack-------------------------------------
1533 class Node_Stack {
1534   friend class VMStructs;
1535 protected:
1536   struct INode {
1537     Node *node; // Processed node
1538     uint  indx; // Index of next node's child
1539   };
1540   INode *_inode_top; // tos, stack grows up
1541   INode *_inode_max; // End of _inodes == _inodes + _max
1542   INode *_inodes;    // Array storage for the stack
1543   Arena *_a;         // Arena to allocate in
1544   void grow();
1545 public:
1546   Node_Stack(int size) {
1547     size_t max = (size > OptoNodeListSize) ? size : OptoNodeListSize;
1548     _a = Thread::current()->resource_area();
1549     _inodes = NEW_ARENA_ARRAY( _a, INode, max );
1550     _inode_max = _inodes + max;
1551     _inode_top = _inodes - 1; // stack is empty
1552   }
1553 
1554   Node_Stack(Arena *a, int size) : _a(a) {
1555     size_t max = (size > OptoNodeListSize) ? size : OptoNodeListSize;
1556     _inodes = NEW_ARENA_ARRAY( _a, INode, max );
1557     _inode_max = _inodes + max;
1558     _inode_top = _inodes - 1; // stack is empty
1559   }
1560 
1561   void pop() {
1562     assert(_inode_top >= _inodes, "node stack underflow");
1563     --_inode_top;
1564   }
1565   void push(Node *n, uint i) {
1566     ++_inode_top;
1567     if (_inode_top >= _inode_max) grow();
1568     INode *top = _inode_top; // optimization
1569     top->node = n;
1570     top->indx = i;
1571   }
1572   Node *node() const {
1573     return _inode_top->node;
1574   }
1575   Node* node_at(uint i) const {
1576     assert(_inodes + i <= _inode_top, "in range");
1577     return _inodes[i].node;
1578   }
1579   uint index() const {
1580     return _inode_top->indx;
1581   }
1582   uint index_at(uint i) const {
1583     assert(_inodes + i <= _inode_top, "in range");
1584     return _inodes[i].indx;
1585   }
1586   void set_node(Node *n) {
1587     _inode_top->node = n;
1588   }
1589   void set_index(uint i) {
1590     _inode_top->indx = i;
1591   }
1592   uint size_max() const { return (uint)pointer_delta(_inode_max, _inodes,  sizeof(INode)); } // Max size
1593   uint size() const { return (uint)pointer_delta((_inode_top+1), _inodes,  sizeof(INode)); } // Current size
1594   bool is_nonempty() const { return (_inode_top >= _inodes); }
1595   bool is_empty() const { return (_inode_top < _inodes); }
1596   void clear() { _inode_top = _inodes - 1; } // retain storage
1597 
1598   // Node_Stack is used to map nodes.
1599   Node* find(uint idx) const;
1600 };
1601 
1602 
1603 //-----------------------------Node_Notes--------------------------------------
1604 // Debugging or profiling annotations loosely and sparsely associated
1605 // with some nodes.  See Compile::node_notes_at for the accessor.
1606 class Node_Notes VALUE_OBJ_CLASS_SPEC {
1607   friend class VMStructs;
1608   JVMState* _jvms;
1609 
1610 public:
1611   Node_Notes(JVMState* jvms = NULL) {
1612     _jvms = jvms;
1613   }
1614 
1615   JVMState* jvms()            { return _jvms; }
1616   void  set_jvms(JVMState* x) {        _jvms = x; }
1617 
1618   // True if there is nothing here.
1619   bool is_clear() {
1620     return (_jvms == NULL);
1621   }
1622 
1623   // Make there be nothing here.
1624   void clear() {
1625     _jvms = NULL;
1626   }
1627 
1628   // Make a new, clean node notes.
1629   static Node_Notes* make(Compile* C) {
1630     Node_Notes* nn = NEW_ARENA_ARRAY(C->comp_arena(), Node_Notes, 1);
1631     nn->clear();
1632     return nn;
1633   }
1634 
1635   Node_Notes* clone(Compile* C) {
1636     Node_Notes* nn = NEW_ARENA_ARRAY(C->comp_arena(), Node_Notes, 1);
1637     (*nn) = (*this);
1638     return nn;
1639   }
1640 
1641   // Absorb any information from source.
1642   bool update_from(Node_Notes* source) {
1643     bool changed = false;
1644     if (source != NULL) {
1645       if (source->jvms() != NULL) {
1646         set_jvms(source->jvms());
1647         changed = true;
1648       }
1649     }
1650     return changed;
1651   }
1652 };
1653 
1654 // Inlined accessors for Compile::node_nodes that require the preceding class:
1655 inline Node_Notes*
1656 Compile::locate_node_notes(GrowableArray<Node_Notes*>* arr,
1657                            int idx, bool can_grow) {
1658   assert(idx >= 0, "oob");
1659   int block_idx = (idx >> _log2_node_notes_block_size);
1660   int grow_by = (block_idx - (arr == NULL? 0: arr->length()));
1661   if (grow_by >= 0) {
1662     if (!can_grow)  return NULL;
1663     grow_node_notes(arr, grow_by + 1);
1664   }
1665   // (Every element of arr is a sub-array of length _node_notes_block_size.)
1666   return arr->at(block_idx) + (idx & (_node_notes_block_size-1));
1667 }
1668 
1669 inline bool
1670 Compile::set_node_notes_at(int idx, Node_Notes* value) {
1671   if (value == NULL || value->is_clear())
1672     return false;  // nothing to write => write nothing
1673   Node_Notes* loc = locate_node_notes(_node_note_array, idx, true);
1674   assert(loc != NULL, "");
1675   return loc->update_from(value);
1676 }
1677 
1678 
1679 //------------------------------TypeNode---------------------------------------
1680 // Node with a Type constant.
1681 class TypeNode : public Node {
1682 protected:
1683   virtual uint hash() const;    // Check the type
1684   virtual uint cmp( const Node &n ) const;
1685   virtual uint size_of() const; // Size is bigger
1686   const Type* const _type;
1687 public:
1688   void set_type(const Type* t) {
1689     assert(t != NULL, "sanity");
1690     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
1691     *(const Type**)&_type = t;   // cast away const-ness
1692     // If this node is in the hash table, make sure it doesn't need a rehash.
1693     assert(check_hash == NO_HASH || check_hash == hash(), "type change must preserve hash code");
1694   }
1695   const Type* type() const { assert(_type != NULL, "sanity"); return _type; };
1696   TypeNode( const Type *t, uint required ) : Node(required), _type(t) {
1697     init_class_id(Class_Type);
1698   }
1699   virtual const Type* Value(PhaseGVN* phase) const;
1700   virtual const Type *bottom_type() const;
1701   virtual       uint  ideal_reg() const;
1702 #ifndef PRODUCT
1703   virtual void dump_spec(outputStream *st) const;
1704   virtual void dump_compact_spec(outputStream *st) const;
1705 #endif
1706 };
1707 
1708 #endif // SHARE_VM_OPTO_NODE_HPP