1 /*
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   3  * Copyright (c) 2024, 2025, Alibaba Group Holding Limited. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
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  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
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  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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  25 
  26 #ifndef SHARE_OPTO_NODE_HPP
  27 #define SHARE_OPTO_NODE_HPP
  28 
  29 #include "libadt/vectset.hpp"
  30 #include "opto/compile.hpp"
  31 #include "opto/type.hpp"
  32 #include "utilities/copy.hpp"
  33 
  34 // Portions of code courtesy of Clifford Click
  35 
  36 // Optimization - Graph Style
  37 
  38 
  39 class AbstractLockNode;
  40 class AddNode;
  41 class AddPNode;
  42 class AliasInfo;
  43 class AllocateArrayNode;
  44 class AllocateNode;
  45 class ArrayCopyNode;
  46 class BaseCountedLoopNode;
  47 class BaseCountedLoopEndNode;
  48 class BlackholeNode;
  49 class Block;
  50 class BoolNode;
  51 class BoxLockNode;
  52 class CMoveNode;
  53 class CallDynamicJavaNode;
  54 class CallJavaNode;
  55 class CallLeafNode;
  56 class CallLeafNoFPNode;
  57 class CallNode;
  58 class CallRuntimeNode;
  59 class CallStaticJavaNode;
  60 class CastFFNode;
  61 class CastHHNode;
  62 class CastDDNode;
  63 class CastVVNode;
  64 class CastIINode;
  65 class CastLLNode;
  66 class CastPPNode;
  67 class CatchNode;
  68 class CatchProjNode;
  69 class CheckCastPPNode;
  70 class ClearArrayNode;
  71 class CmpNode;
  72 class CodeBuffer;
  73 class ConstraintCastNode;
  74 class ConNode;
  75 class ConINode;
  76 class ConvertNode;
  77 class CompareAndSwapNode;
  78 class CompareAndExchangeNode;
  79 class CountedLoopNode;
  80 class CountedLoopEndNode;
  81 class DecodeNarrowPtrNode;
  82 class DecodeNNode;
  83 class DecodeNKlassNode;
  84 class EncodeNarrowPtrNode;
  85 class EncodePNode;
  86 class EncodePKlassNode;
  87 class FastLockNode;
  88 class FastUnlockNode;
  89 class HaltNode;
  90 class IfNode;
  91 class IfProjNode;
  92 class IfFalseNode;
  93 class IfTrueNode;
  94 class InitializeNode;
  95 class JVMState;
  96 class JumpNode;
  97 class JumpProjNode;
  98 class LoadNode;
  99 class LoadStoreNode;
 100 class LoadStoreConditionalNode;
 101 class LockNode;
 102 class LongCountedLoopNode;
 103 class LongCountedLoopEndNode;
 104 class LoopNode;
 105 class LShiftNode;
 106 class MachBranchNode;
 107 class MachCallDynamicJavaNode;
 108 class MachCallJavaNode;
 109 class MachCallLeafNode;
 110 class MachCallNode;
 111 class MachCallRuntimeNode;
 112 class MachCallStaticJavaNode;
 113 class MachConstantBaseNode;
 114 class MachConstantNode;
 115 class MachGotoNode;
 116 class MachIfNode;
 117 class MachJumpNode;
 118 class MachNode;
 119 class MachNullCheckNode;
 120 class MachProjNode;
 121 class MachReturnNode;
 122 class MachSafePointNode;
 123 class MachSpillCopyNode;
 124 class MachTempNode;
 125 class MachMergeNode;
 126 class MachMemBarNode;
 127 class Matcher;
 128 class MemBarNode;
 129 class MemBarStoreStoreNode;
 130 class MemNode;
 131 class MergeMemNode;
 132 class MoveNode;
 133 class MulNode;
 134 class MultiNode;
 135 class MultiBranchNode;
 136 class NegNode;
 137 class NegVNode;
 138 class NeverBranchNode;
 139 class Opaque1Node;
 140 class OpaqueLoopInitNode;
 141 class OpaqueLoopStrideNode;
 142 class OpaqueMultiversioningNode;
 143 class OpaqueNotNullNode;
 144 class OpaqueInitializedAssertionPredicateNode;
 145 class OpaqueTemplateAssertionPredicateNode;
 146 class OuterStripMinedLoopNode;
 147 class OuterStripMinedLoopEndNode;
 148 class Node;
 149 class Node_Array;
 150 class Node_List;
 151 class Node_Stack;
 152 class OopMap;
 153 class ParmNode;
 154 class ParsePredicateNode;
 155 class PCTableNode;
 156 class PhaseCCP;
 157 class PhaseGVN;
 158 class PhaseIdealLoop;
 159 class PhaseIterGVN;
 160 class PhaseRegAlloc;
 161 class PhaseTransform;
 162 class PhaseValues;
 163 class PhiNode;
 164 class Pipeline;
 165 class PopulateIndexNode;
 166 class ProjNode;
 167 class RangeCheckNode;
 168 class ReductionNode;
 169 class RegMask;
 170 class RegionNode;
 171 class RootNode;
 172 class SafePointNode;
 173 class SafePointScalarObjectNode;
 174 class SafePointScalarMergeNode;
 175 class SaturatingVectorNode;
 176 class StartNode;
 177 class State;
 178 class StoreNode;
 179 class SubNode;
 180 class SubTypeCheckNode;
 181 class Type;
 182 class TypeNode;
 183 class UnlockNode;
 184 class VectorNode;
 185 class LoadVectorNode;
 186 class LoadVectorMaskedNode;
 187 class StoreVectorMaskedNode;
 188 class LoadVectorGatherNode;
 189 class LoadVectorGatherMaskedNode;
 190 class StoreVectorNode;
 191 class StoreVectorScatterNode;
 192 class StoreVectorScatterMaskedNode;
 193 class VerifyVectorAlignmentNode;
 194 class VectorMaskCmpNode;
 195 class VectorUnboxNode;
 196 class VectorSet;
 197 class VectorReinterpretNode;
 198 class ShiftVNode;
 199 class MulVLNode;
 200 class ExpandVNode;
 201 class CompressVNode;
 202 class CompressMNode;
 203 class C2_MacroAssembler;
 204 
 205 
 206 #ifndef OPTO_DU_ITERATOR_ASSERT
 207 #ifdef ASSERT
 208 #define OPTO_DU_ITERATOR_ASSERT 1
 209 #else
 210 #define OPTO_DU_ITERATOR_ASSERT 0
 211 #endif
 212 #endif //OPTO_DU_ITERATOR_ASSERT
 213 
 214 #if OPTO_DU_ITERATOR_ASSERT
 215 class DUIterator;
 216 class DUIterator_Fast;
 217 class DUIterator_Last;
 218 #else
 219 typedef uint   DUIterator;
 220 typedef Node** DUIterator_Fast;
 221 typedef Node** DUIterator_Last;
 222 #endif
 223 
 224 typedef ResizeableResourceHashtable<Node*, Node*, AnyObj::RESOURCE_AREA, mtCompiler> OrigToNewHashtable;
 225 
 226 // Node Sentinel
 227 #define NodeSentinel (Node*)-1
 228 
 229 // Unknown count frequency
 230 #define COUNT_UNKNOWN (-1.0f)
 231 
 232 //------------------------------Node-------------------------------------------
 233 // Nodes define actions in the program.  They create values, which have types.
 234 // They are both vertices in a directed graph and program primitives.  Nodes
 235 // are labeled; the label is the "opcode", the primitive function in the lambda
 236 // calculus sense that gives meaning to the Node.  Node inputs are ordered (so
 237 // that "a-b" is different from "b-a").  The inputs to a Node are the inputs to
 238 // the Node's function.  These inputs also define a Type equation for the Node.
 239 // Solving these Type equations amounts to doing dataflow analysis.
 240 // Control and data are uniformly represented in the graph.  Finally, Nodes
 241 // have a unique dense integer index which is used to index into side arrays
 242 // whenever I have phase-specific information.
 243 
 244 class Node {
 245 
 246   // Lots of restrictions on cloning Nodes
 247   NONCOPYABLE(Node);
 248 
 249 public:
 250   friend class Compile;
 251   #if OPTO_DU_ITERATOR_ASSERT
 252   friend class DUIterator_Common;
 253   friend class DUIterator;
 254   friend class DUIterator_Fast;
 255   friend class DUIterator_Last;
 256   #endif
 257 
 258   // Because Nodes come and go, I define an Arena of Node structures to pull
 259   // from.  This should allow fast access to node creation & deletion.  This
 260   // field is a local cache of a value defined in some "program fragment" for
 261   // which these Nodes are just a part of.
 262 
 263   inline void* operator new(size_t x) throw() {
 264     Compile* C = Compile::current();
 265     Node* n = (Node*)C->node_arena()->AmallocWords(x);
 266     return (void*)n;
 267   }
 268 
 269   // Delete is a NOP
 270   void operator delete( void *ptr ) {}
 271   // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 272   void destruct(PhaseValues* phase);
 273 
 274   // Create a new Node.  Required is the number is of inputs required for
 275   // semantic correctness.
 276   Node( uint required );
 277 
 278   // Create a new Node with given input edges.
 279   // This version requires use of the "edge-count" new.
 280   // E.g.  new (C,3) FooNode( C, nullptr, left, right );
 281   Node( Node *n0 );
 282   Node( Node *n0, Node *n1 );
 283   Node( Node *n0, Node *n1, Node *n2 );
 284   Node( Node *n0, Node *n1, Node *n2, Node *n3 );
 285   Node( Node *n0, Node *n1, Node *n2, Node *n3, Node *n4 );
 286   Node( Node *n0, Node *n1, Node *n2, Node *n3, Node *n4, Node *n5 );
 287   Node( Node *n0, Node *n1, Node *n2, Node *n3,
 288             Node *n4, Node *n5, Node *n6 );
 289 
 290   // Clone an inherited Node given only the base Node type.
 291   Node* clone() const;
 292 
 293   // Clone a Node, immediately supplying one or two new edges.
 294   // The first and second arguments, if non-null, replace in(1) and in(2),
 295   // respectively.
 296   Node* clone_with_data_edge(Node* in1, Node* in2 = nullptr) const {
 297     Node* nn = clone();
 298     if (in1 != nullptr)  nn->set_req(1, in1);
 299     if (in2 != nullptr)  nn->set_req(2, in2);
 300     return nn;
 301   }
 302 
 303 private:
 304   // Shared setup for the above constructors.
 305   // Handles all interactions with Compile::current.
 306   // Puts initial values in all Node fields except _idx.
 307   // Returns the initial value for _idx, which cannot
 308   // be initialized by assignment.
 309   inline int Init(int req);
 310 
 311 //----------------- input edge handling
 312 protected:
 313   friend class PhaseCFG;        // Access to address of _in array elements
 314   Node **_in;                   // Array of use-def references to Nodes
 315   Node **_out;                  // Array of def-use references to Nodes
 316 
 317   // Input edges are split into two categories.  Required edges are required
 318   // for semantic correctness; order is important and nulls are allowed.
 319   // Precedence edges are used to help determine execution order and are
 320   // added, e.g., for scheduling purposes.  They are unordered and not
 321   // duplicated; they have no embedded nulls.  Edges from 0 to _cnt-1
 322   // are required, from _cnt to _max-1 are precedence edges.
 323   node_idx_t _cnt;              // Total number of required Node inputs.
 324 
 325   node_idx_t _max;              // Actual length of input array.
 326 
 327   // Output edges are an unordered list of def-use edges which exactly
 328   // correspond to required input edges which point from other nodes
 329   // to this one.  Thus the count of the output edges is the number of
 330   // users of this node.
 331   node_idx_t _outcnt;           // Total number of Node outputs.
 332 
 333   node_idx_t _outmax;           // Actual length of output array.
 334 
 335   // Grow the actual input array to the next larger power-of-2 bigger than len.
 336   void grow( uint len );
 337   // Grow the output array to the next larger power-of-2 bigger than len.
 338   void out_grow( uint len );
 339   // Resize input or output array to grow it to the next larger power-of-2
 340   // bigger than len.
 341   void resize_array(Node**& array, node_idx_t& max_size, uint len, bool needs_clearing);
 342 
 343 public:
 344   // Each Node is assigned a unique small/dense number. This number is used
 345   // to index into auxiliary arrays of data and bit vectors.
 346   // The value of _idx can be changed using the set_idx() method.
 347   //
 348   // The PhaseRenumberLive phase renumbers nodes based on liveness information.
 349   // Therefore, it updates the value of the _idx field. The parse-time _idx is
 350   // preserved in _parse_idx.
 351   node_idx_t _idx;
 352   DEBUG_ONLY(const node_idx_t _parse_idx;)
 353   // IGV node identifier. Two nodes, possibly in different compilation phases,
 354   // have the same IGV identifier if (and only if) they are the very same node
 355   // (same memory address) or one is "derived" from the other (by e.g.
 356   // renumbering or matching). This identifier makes it possible to follow the
 357   // entire lifetime of a node in IGV even if its C2 identifier (_idx) changes.
 358   NOT_PRODUCT(node_idx_t _igv_idx;)
 359 
 360   // Get the (read-only) number of input edges
 361   uint req() const { return _cnt; }
 362   uint len() const { return _max; }
 363   // Get the (read-only) number of output edges
 364   uint outcnt() const { return _outcnt; }
 365 
 366 #if OPTO_DU_ITERATOR_ASSERT
 367   // Iterate over the out-edges of this node.  Deletions are illegal.
 368   inline DUIterator outs() const;
 369   // Use this when the out array might have changed to suppress asserts.
 370   inline DUIterator& refresh_out_pos(DUIterator& i) const;
 371   // Does the node have an out at this position?  (Used for iteration.)
 372   inline bool has_out(DUIterator& i) const;
 373   inline Node*    out(DUIterator& i) const;
 374   // Iterate over the out-edges of this node.  All changes are illegal.
 375   inline DUIterator_Fast fast_outs(DUIterator_Fast& max) const;
 376   inline Node*    fast_out(DUIterator_Fast& i) const;
 377   // Iterate over the out-edges of this node, deleting one at a time.
 378   inline DUIterator_Last last_outs(DUIterator_Last& min) const;
 379   inline Node*    last_out(DUIterator_Last& i) const;
 380   // The inline bodies of all these methods are after the iterator definitions.
 381 #else
 382   // Iterate over the out-edges of this node.  Deletions are illegal.
 383   // This iteration uses integral indexes, to decouple from array reallocations.
 384   DUIterator outs() const  { return 0; }
 385   // Use this when the out array might have changed to suppress asserts.
 386   DUIterator refresh_out_pos(DUIterator i) const { return i; }
 387 
 388   // Reference to the i'th output Node.  Error if out of bounds.
 389   Node*    out(DUIterator i) const { assert(i < _outcnt, "oob"); return _out[i]; }
 390   // Does the node have an out at this position?  (Used for iteration.)
 391   bool has_out(DUIterator i) const { return i < _outcnt; }
 392 
 393   // Iterate over the out-edges of this node.  All changes are illegal.
 394   // This iteration uses a pointer internal to the out array.
 395   DUIterator_Fast fast_outs(DUIterator_Fast& max) const {
 396     Node** out = _out;
 397     // Assign a limit pointer to the reference argument:
 398     max = out + (ptrdiff_t)_outcnt;
 399     // Return the base pointer:
 400     return out;
 401   }
 402   Node*    fast_out(DUIterator_Fast i) const  { return *i; }
 403   // Iterate over the out-edges of this node, deleting one at a time.
 404   // This iteration uses a pointer internal to the out array.
 405   DUIterator_Last last_outs(DUIterator_Last& min) const {
 406     Node** out = _out;
 407     // Assign a limit pointer to the reference argument:
 408     min = out;
 409     // Return the pointer to the start of the iteration:
 410     return out + (ptrdiff_t)_outcnt - 1;
 411   }
 412   Node*    last_out(DUIterator_Last i) const  { return *i; }
 413 #endif
 414 
 415   // Reference to the i'th input Node.  Error if out of bounds.
 416   Node* in(uint i) const { assert(i < _max, "oob: i=%d, _max=%d", i, _max); return _in[i]; }
 417   // Reference to the i'th input Node.  null if out of bounds.
 418   Node* lookup(uint i) const { return ((i < _max) ? _in[i] : nullptr); }
 419   // Reference to the i'th output Node.  Error if out of bounds.
 420   // Use this accessor sparingly.  We are going trying to use iterators instead.
 421   Node* raw_out(uint i) const { assert(i < _outcnt,"oob"); return _out[i]; }
 422   // Return the unique out edge.
 423   Node* unique_out() const { assert(_outcnt==1,"not unique"); return _out[0]; }
 424   // Delete out edge at position 'i' by moving last out edge to position 'i'
 425   void  raw_del_out(uint i) {
 426     assert(i < _outcnt,"oob");
 427     assert(_outcnt > 0,"oob");
 428     #if OPTO_DU_ITERATOR_ASSERT
 429     // Record that a change happened here.
 430     debug_only(_last_del = _out[i]; ++_del_tick);
 431     #endif
 432     _out[i] = _out[--_outcnt];
 433     // Smash the old edge so it can't be used accidentally.
 434     debug_only(_out[_outcnt] = (Node *)(uintptr_t)0xdeadbeef);
 435   }
 436 
 437 #ifdef ASSERT
 438   bool is_dead() const;
 439   static bool is_not_dead(const Node* n);
 440   bool is_reachable_from_root() const;
 441 #endif
 442   // Check whether node has become unreachable
 443   bool is_unreachable(PhaseIterGVN &igvn) const;
 444 
 445   // Set a required input edge, also updates corresponding output edge
 446   void add_req( Node *n ); // Append a NEW required input
 447   void add_req( Node *n0, Node *n1 ) {
 448     add_req(n0); add_req(n1); }
 449   void add_req( Node *n0, Node *n1, Node *n2 ) {
 450     add_req(n0); add_req(n1); add_req(n2); }
 451   void add_req_batch( Node* n, uint m ); // Append m NEW required inputs (all n).
 452   void del_req( uint idx ); // Delete required edge & compact
 453   void del_req_ordered( uint idx ); // Delete required edge & compact with preserved order
 454   void ins_req( uint i, Node *n ); // Insert a NEW required input
 455   void set_req( uint i, Node *n ) {
 456     assert( is_not_dead(n), "can not use dead node");
 457     assert( i < _cnt, "oob: i=%d, _cnt=%d", i, _cnt);
 458     assert( !VerifyHashTableKeys || _hash_lock == 0,
 459             "remove node from hash table before modifying it");
 460     Node** p = &_in[i];    // cache this._in, across the del_out call
 461     if (*p != nullptr)  (*p)->del_out((Node *)this);
 462     (*p) = n;
 463     if (n != nullptr)      n->add_out((Node *)this);
 464     Compile::current()->record_modified_node(this);
 465   }
 466   // Light version of set_req() to init inputs after node creation.
 467   void init_req( uint i, Node *n ) {
 468     assert( (i == 0 && this == n) ||
 469             is_not_dead(n), "can not use dead node");
 470     assert( i < _cnt, "oob");
 471     assert( !VerifyHashTableKeys || _hash_lock == 0,
 472             "remove node from hash table before modifying it");
 473     assert( _in[i] == nullptr, "sanity");
 474     _in[i] = n;
 475     if (n != nullptr)      n->add_out((Node *)this);
 476     Compile::current()->record_modified_node(this);
 477   }
 478   // Find first occurrence of n among my edges:
 479   int find_edge(Node* n);
 480   int find_prec_edge(Node* n) {
 481     for (uint i = req(); i < len(); i++) {
 482       if (_in[i] == n) return i;
 483       if (_in[i] == nullptr) {
 484         DEBUG_ONLY( while ((++i) < len()) assert(_in[i] == nullptr, "Gap in prec edges!"); )
 485         break;
 486       }
 487     }
 488     return -1;
 489   }
 490   int replace_edge(Node* old, Node* neww, PhaseGVN* gvn = nullptr);
 491   int replace_edges_in_range(Node* old, Node* neww, int start, int end, PhaseGVN* gvn);
 492   // null out all inputs to eliminate incoming Def-Use edges.
 493   void disconnect_inputs(Compile* C);
 494 
 495   // Quickly, return true if and only if I am Compile::current()->top().
 496   bool is_top() const {
 497     assert((this == (Node*) Compile::current()->top()) == (_out == nullptr), "");
 498     return (_out == nullptr);
 499   }
 500   // Reaffirm invariants for is_top.  (Only from Compile::set_cached_top_node.)
 501   void setup_is_top();
 502 
 503   // Strip away casting.  (It is depth-limited.)
 504   Node* uncast(bool keep_deps = false) const;
 505   // Return whether two Nodes are equivalent, after stripping casting.
 506   bool eqv_uncast(const Node* n, bool keep_deps = false) const {
 507     return (this->uncast(keep_deps) == n->uncast(keep_deps));
 508   }
 509 
 510   // Find out of current node that matches opcode.
 511   Node* find_out_with(int opcode);
 512   // Return true if the current node has an out that matches opcode.
 513   bool has_out_with(int opcode);
 514   // Return true if the current node has an out that matches any of the opcodes.
 515   bool has_out_with(int opcode1, int opcode2, int opcode3, int opcode4);
 516 
 517 private:
 518   static Node* uncast_helper(const Node* n, bool keep_deps);
 519 
 520   // Add an output edge to the end of the list
 521   void add_out( Node *n ) {
 522     if (is_top())  return;
 523     if( _outcnt == _outmax ) out_grow(_outcnt);
 524     _out[_outcnt++] = n;
 525   }
 526   // Delete an output edge
 527   void del_out( Node *n ) {
 528     if (is_top())  return;
 529     Node** outp = &_out[_outcnt];
 530     // Find and remove n
 531     do {
 532       assert(outp > _out, "Missing Def-Use edge");
 533     } while (*--outp != n);
 534     *outp = _out[--_outcnt];
 535     // Smash the old edge so it can't be used accidentally.
 536     debug_only(_out[_outcnt] = (Node *)(uintptr_t)0xdeadbeef);
 537     // Record that a change happened here.
 538     #if OPTO_DU_ITERATOR_ASSERT
 539     debug_only(_last_del = n; ++_del_tick);
 540     #endif
 541   }
 542   // Close gap after removing edge.
 543   void close_prec_gap_at(uint gap) {
 544     assert(_cnt <= gap && gap < _max, "no valid prec edge");
 545     uint i = gap;
 546     Node *last = nullptr;
 547     for (; i < _max-1; ++i) {
 548       Node *next = _in[i+1];
 549       if (next == nullptr) break;
 550       last = next;
 551     }
 552     _in[gap] = last;  // Move last slot to empty one.
 553     _in[i] = nullptr; // null out last slot.
 554   }
 555 
 556 public:
 557   // Globally replace this node by a given new node, updating all uses.
 558   void replace_by(Node* new_node);
 559   // Globally replace this node by a given new node, updating all uses
 560   // and cutting input edges of old node.
 561   void subsume_by(Node* new_node, Compile* c) {
 562     replace_by(new_node);
 563     disconnect_inputs(c);
 564   }
 565   void set_req_X(uint i, Node *n, PhaseIterGVN *igvn);
 566   void set_req_X(uint i, Node *n, PhaseGVN *gvn);
 567   // Find the one non-null required input.  RegionNode only
 568   Node *nonnull_req() const;
 569   // Add or remove precedence edges
 570   void add_prec( Node *n );
 571   void rm_prec( uint i );
 572 
 573   // Note: prec(i) will not necessarily point to n if edge already exists.
 574   void set_prec( uint i, Node *n ) {
 575     assert(i < _max, "oob: i=%d, _max=%d", i, _max);
 576     assert(is_not_dead(n), "can not use dead node");
 577     assert(i >= _cnt, "not a precedence edge");
 578     // Avoid spec violation: duplicated prec edge.
 579     if (_in[i] == n) return;
 580     if (n == nullptr || find_prec_edge(n) != -1) {
 581       rm_prec(i);
 582       return;
 583     }
 584     if (_in[i] != nullptr) _in[i]->del_out((Node *)this);
 585     _in[i] = n;
 586     n->add_out((Node *)this);
 587     Compile::current()->record_modified_node(this);
 588   }
 589 
 590   // Set this node's index, used by cisc_version to replace current node
 591   void set_idx(uint new_idx) {
 592     _idx = new_idx;
 593   }
 594   // Swap input edge order.  (Edge indexes i1 and i2 are usually 1 and 2.)
 595   void swap_edges(uint i1, uint i2) {
 596     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
 597     // Def-Use info is unchanged
 598     Node* n1 = in(i1);
 599     Node* n2 = in(i2);
 600     _in[i1] = n2;
 601     _in[i2] = n1;
 602     // If this node is in the hash table, make sure it doesn't need a rehash.
 603     assert(check_hash == NO_HASH || check_hash == hash(), "edge swap must preserve hash code");
 604     // Flip swapped edges flag.
 605     if (has_swapped_edges()) {
 606       remove_flag(Node::Flag_has_swapped_edges);
 607     } else {
 608       add_flag(Node::Flag_has_swapped_edges);
 609     }
 610   }
 611 
 612   // Iterators over input Nodes for a Node X are written as:
 613   // for( i = 0; i < X.req(); i++ ) ... X[i] ...
 614   // NOTE: Required edges can contain embedded null pointers.
 615 
 616 //----------------- Other Node Properties
 617 
 618   // Generate class IDs for (some) ideal nodes so that it is possible to determine
 619   // the type of a node using a non-virtual method call (the method is_<Node>() below).
 620   //
 621   // A class ID of an ideal node is a set of bits. In a class ID, a single bit determines
 622   // the type of the node the ID represents; another subset of an ID's bits are reserved
 623   // for the superclasses of the node represented by the ID.
 624   //
 625   // By design, if A is a supertype of B, A.is_B() returns true and B.is_A()
 626   // returns false. A.is_A() returns true.
 627   //
 628   // If two classes, A and B, have the same superclass, a different bit of A's class id
 629   // is reserved for A's type than for B's type. That bit is specified by the third
 630   // parameter in the macro DEFINE_CLASS_ID.
 631   //
 632   // By convention, classes with deeper hierarchy are declared first. Moreover,
 633   // classes with the same hierarchy depth are sorted by usage frequency.
 634   //
 635   // The query method masks the bits to cut off bits of subclasses and then compares
 636   // the result with the class id (see the macro DEFINE_CLASS_QUERY below).
 637   //
 638   //  Class_MachCall=30, ClassMask_MachCall=31
 639   // 12               8               4               0
 640   //  0   0   0   0   0   0   0   0   1   1   1   1   0
 641   //                                  |   |   |   |
 642   //                                  |   |   |   Bit_Mach=2
 643   //                                  |   |   Bit_MachReturn=4
 644   //                                  |   Bit_MachSafePoint=8
 645   //                                  Bit_MachCall=16
 646   //
 647   //  Class_CountedLoop=56, ClassMask_CountedLoop=63
 648   // 12               8               4               0
 649   //  0   0   0   0   0   0   0   1   1   1   0   0   0
 650   //                              |   |   |
 651   //                              |   |   Bit_Region=8
 652   //                              |   Bit_Loop=16
 653   //                              Bit_CountedLoop=32
 654 
 655   #define DEFINE_CLASS_ID(cl, supcl, subn) \
 656   Bit_##cl = (Class_##supcl == 0) ? 1 << subn : (Bit_##supcl) << (1 + subn) , \
 657   Class_##cl = Class_##supcl + Bit_##cl , \
 658   ClassMask_##cl = ((Bit_##cl << 1) - 1) ,
 659 
 660   // This enum is used only for C2 ideal and mach nodes with is_<node>() methods
 661   // so that its values fit into 32 bits.
 662   enum NodeClasses {
 663     Bit_Node   = 0x00000000,
 664     Class_Node = 0x00000000,
 665     ClassMask_Node = 0xFFFFFFFF,
 666 
 667     DEFINE_CLASS_ID(Multi, Node, 0)
 668       DEFINE_CLASS_ID(SafePoint, Multi, 0)
 669         DEFINE_CLASS_ID(Call,      SafePoint, 0)
 670           DEFINE_CLASS_ID(CallJava,         Call, 0)
 671             DEFINE_CLASS_ID(CallStaticJava,   CallJava, 0)
 672             DEFINE_CLASS_ID(CallDynamicJava,  CallJava, 1)
 673           DEFINE_CLASS_ID(CallRuntime,      Call, 1)
 674             DEFINE_CLASS_ID(CallLeaf,         CallRuntime, 0)
 675               DEFINE_CLASS_ID(CallLeafNoFP,     CallLeaf, 0)
 676           DEFINE_CLASS_ID(Allocate,         Call, 2)
 677             DEFINE_CLASS_ID(AllocateArray,    Allocate, 0)
 678           DEFINE_CLASS_ID(AbstractLock,     Call, 3)
 679             DEFINE_CLASS_ID(Lock,             AbstractLock, 0)
 680             DEFINE_CLASS_ID(Unlock,           AbstractLock, 1)
 681           DEFINE_CLASS_ID(ArrayCopy,        Call, 4)
 682       DEFINE_CLASS_ID(MultiBranch, Multi, 1)
 683         DEFINE_CLASS_ID(PCTable,     MultiBranch, 0)
 684           DEFINE_CLASS_ID(Catch,       PCTable, 0)
 685           DEFINE_CLASS_ID(Jump,        PCTable, 1)
 686         DEFINE_CLASS_ID(If,          MultiBranch, 1)
 687           DEFINE_CLASS_ID(BaseCountedLoopEnd,     If, 0)
 688             DEFINE_CLASS_ID(CountedLoopEnd,       BaseCountedLoopEnd, 0)
 689             DEFINE_CLASS_ID(LongCountedLoopEnd,   BaseCountedLoopEnd, 1)
 690           DEFINE_CLASS_ID(RangeCheck,             If, 1)
 691           DEFINE_CLASS_ID(OuterStripMinedLoopEnd, If, 2)
 692           DEFINE_CLASS_ID(ParsePredicate,         If, 3)
 693         DEFINE_CLASS_ID(NeverBranch, MultiBranch, 2)
 694       DEFINE_CLASS_ID(Start,       Multi, 2)
 695       DEFINE_CLASS_ID(MemBar,      Multi, 3)
 696         DEFINE_CLASS_ID(Initialize,       MemBar, 0)
 697         DEFINE_CLASS_ID(MemBarStoreStore, MemBar, 1)
 698 
 699     DEFINE_CLASS_ID(Mach,  Node, 1)
 700       DEFINE_CLASS_ID(MachReturn, Mach, 0)
 701         DEFINE_CLASS_ID(MachSafePoint, MachReturn, 0)
 702           DEFINE_CLASS_ID(MachCall, MachSafePoint, 0)
 703             DEFINE_CLASS_ID(MachCallJava,         MachCall, 0)
 704               DEFINE_CLASS_ID(MachCallStaticJava,   MachCallJava, 0)
 705               DEFINE_CLASS_ID(MachCallDynamicJava,  MachCallJava, 1)
 706             DEFINE_CLASS_ID(MachCallRuntime,      MachCall, 1)
 707               DEFINE_CLASS_ID(MachCallLeaf,         MachCallRuntime, 0)
 708       DEFINE_CLASS_ID(MachBranch, Mach, 1)
 709         DEFINE_CLASS_ID(MachIf,         MachBranch, 0)
 710         DEFINE_CLASS_ID(MachGoto,       MachBranch, 1)
 711         DEFINE_CLASS_ID(MachNullCheck,  MachBranch, 2)
 712       DEFINE_CLASS_ID(MachSpillCopy,    Mach, 2)
 713       DEFINE_CLASS_ID(MachTemp,         Mach, 3)
 714       DEFINE_CLASS_ID(MachConstantBase, Mach, 4)
 715       DEFINE_CLASS_ID(MachConstant,     Mach, 5)
 716         DEFINE_CLASS_ID(MachJump,       MachConstant, 0)
 717       DEFINE_CLASS_ID(MachMerge,        Mach, 6)
 718       DEFINE_CLASS_ID(MachMemBar,       Mach, 7)
 719 
 720     DEFINE_CLASS_ID(Type,  Node, 2)
 721       DEFINE_CLASS_ID(Phi,   Type, 0)
 722       DEFINE_CLASS_ID(ConstraintCast, Type, 1)
 723         DEFINE_CLASS_ID(CastII, ConstraintCast, 0)
 724         DEFINE_CLASS_ID(CheckCastPP, ConstraintCast, 1)
 725         DEFINE_CLASS_ID(CastLL, ConstraintCast, 2)
 726         DEFINE_CLASS_ID(CastFF, ConstraintCast, 3)
 727         DEFINE_CLASS_ID(CastDD, ConstraintCast, 4)
 728         DEFINE_CLASS_ID(CastVV, ConstraintCast, 5)
 729         DEFINE_CLASS_ID(CastPP, ConstraintCast, 6)
 730         DEFINE_CLASS_ID(CastHH, ConstraintCast, 7)
 731       DEFINE_CLASS_ID(CMove, Type, 3)
 732       DEFINE_CLASS_ID(SafePointScalarObject, Type, 4)
 733       DEFINE_CLASS_ID(DecodeNarrowPtr, Type, 5)
 734         DEFINE_CLASS_ID(DecodeN, DecodeNarrowPtr, 0)
 735         DEFINE_CLASS_ID(DecodeNKlass, DecodeNarrowPtr, 1)
 736       DEFINE_CLASS_ID(EncodeNarrowPtr, Type, 6)
 737         DEFINE_CLASS_ID(EncodeP, EncodeNarrowPtr, 0)
 738         DEFINE_CLASS_ID(EncodePKlass, EncodeNarrowPtr, 1)
 739       DEFINE_CLASS_ID(Vector, Type, 7)
 740         DEFINE_CLASS_ID(VectorMaskCmp, Vector, 0)
 741         DEFINE_CLASS_ID(VectorUnbox, Vector, 1)
 742         DEFINE_CLASS_ID(VectorReinterpret, Vector, 2)
 743         DEFINE_CLASS_ID(ShiftV, Vector, 3)
 744         DEFINE_CLASS_ID(CompressV, Vector, 4)
 745         DEFINE_CLASS_ID(ExpandV, Vector, 5)
 746         DEFINE_CLASS_ID(CompressM, Vector, 6)
 747         DEFINE_CLASS_ID(Reduction, Vector, 7)
 748         DEFINE_CLASS_ID(NegV, Vector, 8)
 749         DEFINE_CLASS_ID(SaturatingVector, Vector, 9)
 750         DEFINE_CLASS_ID(MulVL, Vector, 10)
 751       DEFINE_CLASS_ID(Con, Type, 8)
 752           DEFINE_CLASS_ID(ConI, Con, 0)
 753       DEFINE_CLASS_ID(SafePointScalarMerge, Type, 9)
 754       DEFINE_CLASS_ID(Convert, Type, 10)
 755 
 756 
 757     DEFINE_CLASS_ID(Proj,  Node, 3)
 758       DEFINE_CLASS_ID(CatchProj, Proj, 0)
 759       DEFINE_CLASS_ID(JumpProj,  Proj, 1)
 760       DEFINE_CLASS_ID(IfProj,    Proj, 2)
 761         DEFINE_CLASS_ID(IfTrue,    IfProj, 0)
 762         DEFINE_CLASS_ID(IfFalse,   IfProj, 1)
 763       DEFINE_CLASS_ID(Parm,      Proj, 4)
 764       DEFINE_CLASS_ID(MachProj,  Proj, 5)
 765 
 766     DEFINE_CLASS_ID(Mem, Node, 4)
 767       DEFINE_CLASS_ID(Load, Mem, 0)
 768         DEFINE_CLASS_ID(LoadVector,  Load, 0)
 769           DEFINE_CLASS_ID(LoadVectorGather, LoadVector, 0)
 770           DEFINE_CLASS_ID(LoadVectorGatherMasked, LoadVector, 1)
 771           DEFINE_CLASS_ID(LoadVectorMasked, LoadVector, 2)
 772       DEFINE_CLASS_ID(Store, Mem, 1)
 773         DEFINE_CLASS_ID(StoreVector, Store, 0)
 774           DEFINE_CLASS_ID(StoreVectorScatter, StoreVector, 0)
 775           DEFINE_CLASS_ID(StoreVectorScatterMasked, StoreVector, 1)
 776           DEFINE_CLASS_ID(StoreVectorMasked, StoreVector, 2)
 777       DEFINE_CLASS_ID(LoadStore, Mem, 2)
 778         DEFINE_CLASS_ID(LoadStoreConditional, LoadStore, 0)
 779           DEFINE_CLASS_ID(CompareAndSwap, LoadStoreConditional, 0)
 780         DEFINE_CLASS_ID(CompareAndExchangeNode, LoadStore, 1)
 781 
 782     DEFINE_CLASS_ID(Region, Node, 5)
 783       DEFINE_CLASS_ID(Loop, Region, 0)
 784         DEFINE_CLASS_ID(Root,                Loop, 0)
 785         DEFINE_CLASS_ID(BaseCountedLoop,     Loop, 1)
 786           DEFINE_CLASS_ID(CountedLoop,       BaseCountedLoop, 0)
 787           DEFINE_CLASS_ID(LongCountedLoop,   BaseCountedLoop, 1)
 788         DEFINE_CLASS_ID(OuterStripMinedLoop, Loop, 2)
 789 
 790     DEFINE_CLASS_ID(Sub,   Node, 6)
 791       DEFINE_CLASS_ID(Cmp,   Sub, 0)
 792         DEFINE_CLASS_ID(FastLock,   Cmp, 0)
 793         DEFINE_CLASS_ID(FastUnlock, Cmp, 1)
 794         DEFINE_CLASS_ID(SubTypeCheck,Cmp, 2)
 795 
 796     DEFINE_CLASS_ID(MergeMem, Node, 7)
 797     DEFINE_CLASS_ID(Bool,     Node, 8)
 798     DEFINE_CLASS_ID(AddP,     Node, 9)
 799     DEFINE_CLASS_ID(BoxLock,  Node, 10)
 800     DEFINE_CLASS_ID(Add,      Node, 11)
 801     DEFINE_CLASS_ID(Mul,      Node, 12)
 802     DEFINE_CLASS_ID(ClearArray, Node, 14)
 803     DEFINE_CLASS_ID(Halt,     Node, 15)
 804     DEFINE_CLASS_ID(Opaque1,  Node, 16)
 805       DEFINE_CLASS_ID(OpaqueLoopInit, Opaque1, 0)
 806       DEFINE_CLASS_ID(OpaqueLoopStride, Opaque1, 1)
 807       DEFINE_CLASS_ID(OpaqueMultiversioning, Opaque1, 2)
 808     DEFINE_CLASS_ID(OpaqueNotNull,  Node, 17)
 809     DEFINE_CLASS_ID(OpaqueInitializedAssertionPredicate,  Node, 18)
 810     DEFINE_CLASS_ID(OpaqueTemplateAssertionPredicate,  Node, 19)
 811     DEFINE_CLASS_ID(Move,     Node, 20)
 812     DEFINE_CLASS_ID(LShift,   Node, 21)
 813     DEFINE_CLASS_ID(Neg,      Node, 22)
 814 
 815     _max_classes  = ClassMask_Neg
 816   };
 817   #undef DEFINE_CLASS_ID
 818 
 819   // Flags are sorted by usage frequency.
 820   enum NodeFlags {
 821     Flag_is_Copy                     = 1 << 0, // should be first bit to avoid shift
 822     Flag_rematerialize               = 1 << 1,
 823     Flag_needs_anti_dependence_check = 1 << 2,
 824     Flag_is_macro                    = 1 << 3,
 825     Flag_is_Con                      = 1 << 4,
 826     Flag_is_cisc_alternate           = 1 << 5,
 827     Flag_is_dead_loop_safe           = 1 << 6,
 828     Flag_may_be_short_branch         = 1 << 7,
 829     Flag_avoid_back_to_back_before   = 1 << 8,
 830     Flag_avoid_back_to_back_after    = 1 << 9,
 831     Flag_has_call                    = 1 << 10,
 832     Flag_has_swapped_edges           = 1 << 11,
 833     Flag_is_scheduled                = 1 << 12,
 834     Flag_is_expensive                = 1 << 13,
 835     Flag_is_predicated_vector        = 1 << 14,
 836     Flag_for_post_loop_opts_igvn     = 1 << 15,
 837     Flag_for_merge_stores_igvn       = 1 << 16,
 838     Flag_is_removed_by_peephole      = 1 << 17,
 839     Flag_is_predicated_using_blend   = 1 << 18,
 840     _last_flag                       = Flag_is_predicated_using_blend
 841   };
 842 
 843   class PD;
 844 
 845 private:
 846   juint _class_id;
 847   juint _flags;
 848 
 849 #ifdef ASSERT
 850   static juint max_flags();
 851 #endif
 852 
 853 protected:
 854   // These methods should be called from constructors only.
 855   void init_class_id(juint c) {
 856     _class_id = c; // cast out const
 857   }
 858   void init_flags(uint fl) {
 859     assert(fl <= max_flags(), "invalid node flag");
 860     _flags |= fl;
 861   }
 862   void clear_flag(uint fl) {
 863     assert(fl <= max_flags(), "invalid node flag");
 864     _flags &= ~fl;
 865   }
 866 
 867 public:
 868   juint class_id() const { return _class_id; }
 869 
 870   juint flags() const { return _flags; }
 871 
 872   void add_flag(juint fl) { init_flags(fl); }
 873 
 874   void remove_flag(juint fl) { clear_flag(fl); }
 875 
 876   // Return a dense integer opcode number
 877   virtual int Opcode() const;
 878 
 879   // Virtual inherited Node size
 880   virtual uint size_of() const;
 881 
 882   // Other interesting Node properties
 883   #define DEFINE_CLASS_QUERY(type)                           \
 884   bool is_##type() const {                                   \
 885     return ((_class_id & ClassMask_##type) == Class_##type); \
 886   }                                                          \
 887   type##Node *as_##type() const {                            \
 888     assert(is_##type(), "invalid node class: %s", Name());   \
 889     return (type##Node*)this;                                \
 890   }                                                          \
 891   type##Node* isa_##type() const {                           \
 892     return (is_##type()) ? as_##type() : nullptr;            \
 893   }
 894 
 895   DEFINE_CLASS_QUERY(AbstractLock)
 896   DEFINE_CLASS_QUERY(Add)
 897   DEFINE_CLASS_QUERY(AddP)
 898   DEFINE_CLASS_QUERY(Allocate)
 899   DEFINE_CLASS_QUERY(AllocateArray)
 900   DEFINE_CLASS_QUERY(ArrayCopy)
 901   DEFINE_CLASS_QUERY(BaseCountedLoop)
 902   DEFINE_CLASS_QUERY(BaseCountedLoopEnd)
 903   DEFINE_CLASS_QUERY(Bool)
 904   DEFINE_CLASS_QUERY(BoxLock)
 905   DEFINE_CLASS_QUERY(Call)
 906   DEFINE_CLASS_QUERY(CallDynamicJava)
 907   DEFINE_CLASS_QUERY(CallJava)
 908   DEFINE_CLASS_QUERY(CallLeaf)
 909   DEFINE_CLASS_QUERY(CallLeafNoFP)
 910   DEFINE_CLASS_QUERY(CallRuntime)
 911   DEFINE_CLASS_QUERY(CallStaticJava)
 912   DEFINE_CLASS_QUERY(Catch)
 913   DEFINE_CLASS_QUERY(CatchProj)
 914   DEFINE_CLASS_QUERY(CheckCastPP)
 915   DEFINE_CLASS_QUERY(CastII)
 916   DEFINE_CLASS_QUERY(CastLL)
 917   DEFINE_CLASS_QUERY(CastFF)
 918   DEFINE_CLASS_QUERY(ConI)
 919   DEFINE_CLASS_QUERY(CastPP)
 920   DEFINE_CLASS_QUERY(ConstraintCast)
 921   DEFINE_CLASS_QUERY(ClearArray)
 922   DEFINE_CLASS_QUERY(CMove)
 923   DEFINE_CLASS_QUERY(Cmp)
 924   DEFINE_CLASS_QUERY(Convert)
 925   DEFINE_CLASS_QUERY(CountedLoop)
 926   DEFINE_CLASS_QUERY(CountedLoopEnd)
 927   DEFINE_CLASS_QUERY(DecodeNarrowPtr)
 928   DEFINE_CLASS_QUERY(DecodeN)
 929   DEFINE_CLASS_QUERY(DecodeNKlass)
 930   DEFINE_CLASS_QUERY(EncodeNarrowPtr)
 931   DEFINE_CLASS_QUERY(EncodeP)
 932   DEFINE_CLASS_QUERY(EncodePKlass)
 933   DEFINE_CLASS_QUERY(FastLock)
 934   DEFINE_CLASS_QUERY(FastUnlock)
 935   DEFINE_CLASS_QUERY(Halt)
 936   DEFINE_CLASS_QUERY(If)
 937   DEFINE_CLASS_QUERY(RangeCheck)
 938   DEFINE_CLASS_QUERY(IfProj)
 939   DEFINE_CLASS_QUERY(IfFalse)
 940   DEFINE_CLASS_QUERY(IfTrue)
 941   DEFINE_CLASS_QUERY(Initialize)
 942   DEFINE_CLASS_QUERY(Jump)
 943   DEFINE_CLASS_QUERY(JumpProj)
 944   DEFINE_CLASS_QUERY(LongCountedLoop)
 945   DEFINE_CLASS_QUERY(LongCountedLoopEnd)
 946   DEFINE_CLASS_QUERY(Load)
 947   DEFINE_CLASS_QUERY(LoadStore)
 948   DEFINE_CLASS_QUERY(LoadStoreConditional)
 949   DEFINE_CLASS_QUERY(Lock)
 950   DEFINE_CLASS_QUERY(Loop)
 951   DEFINE_CLASS_QUERY(LShift)
 952   DEFINE_CLASS_QUERY(Mach)
 953   DEFINE_CLASS_QUERY(MachBranch)
 954   DEFINE_CLASS_QUERY(MachCall)
 955   DEFINE_CLASS_QUERY(MachCallDynamicJava)
 956   DEFINE_CLASS_QUERY(MachCallJava)
 957   DEFINE_CLASS_QUERY(MachCallLeaf)
 958   DEFINE_CLASS_QUERY(MachCallRuntime)
 959   DEFINE_CLASS_QUERY(MachCallStaticJava)
 960   DEFINE_CLASS_QUERY(MachConstantBase)
 961   DEFINE_CLASS_QUERY(MachConstant)
 962   DEFINE_CLASS_QUERY(MachGoto)
 963   DEFINE_CLASS_QUERY(MachIf)
 964   DEFINE_CLASS_QUERY(MachJump)
 965   DEFINE_CLASS_QUERY(MachNullCheck)
 966   DEFINE_CLASS_QUERY(MachProj)
 967   DEFINE_CLASS_QUERY(MachReturn)
 968   DEFINE_CLASS_QUERY(MachSafePoint)
 969   DEFINE_CLASS_QUERY(MachSpillCopy)
 970   DEFINE_CLASS_QUERY(MachTemp)
 971   DEFINE_CLASS_QUERY(MachMemBar)
 972   DEFINE_CLASS_QUERY(MachMerge)
 973   DEFINE_CLASS_QUERY(Mem)
 974   DEFINE_CLASS_QUERY(MemBar)
 975   DEFINE_CLASS_QUERY(MemBarStoreStore)
 976   DEFINE_CLASS_QUERY(MergeMem)
 977   DEFINE_CLASS_QUERY(Move)
 978   DEFINE_CLASS_QUERY(Mul)
 979   DEFINE_CLASS_QUERY(Multi)
 980   DEFINE_CLASS_QUERY(MultiBranch)
 981   DEFINE_CLASS_QUERY(MulVL)
 982   DEFINE_CLASS_QUERY(Neg)
 983   DEFINE_CLASS_QUERY(NegV)
 984   DEFINE_CLASS_QUERY(NeverBranch)
 985   DEFINE_CLASS_QUERY(Opaque1)
 986   DEFINE_CLASS_QUERY(OpaqueNotNull)
 987   DEFINE_CLASS_QUERY(OpaqueInitializedAssertionPredicate)
 988   DEFINE_CLASS_QUERY(OpaqueTemplateAssertionPredicate)
 989   DEFINE_CLASS_QUERY(OpaqueLoopInit)
 990   DEFINE_CLASS_QUERY(OpaqueLoopStride)
 991   DEFINE_CLASS_QUERY(OpaqueMultiversioning)
 992   DEFINE_CLASS_QUERY(OuterStripMinedLoop)
 993   DEFINE_CLASS_QUERY(OuterStripMinedLoopEnd)
 994   DEFINE_CLASS_QUERY(Parm)
 995   DEFINE_CLASS_QUERY(ParsePredicate)
 996   DEFINE_CLASS_QUERY(PCTable)
 997   DEFINE_CLASS_QUERY(Phi)
 998   DEFINE_CLASS_QUERY(Proj)
 999   DEFINE_CLASS_QUERY(Reduction)
1000   DEFINE_CLASS_QUERY(Region)
1001   DEFINE_CLASS_QUERY(Root)
1002   DEFINE_CLASS_QUERY(SafePoint)
1003   DEFINE_CLASS_QUERY(SafePointScalarObject)
1004   DEFINE_CLASS_QUERY(SafePointScalarMerge)
1005   DEFINE_CLASS_QUERY(Start)
1006   DEFINE_CLASS_QUERY(Store)
1007   DEFINE_CLASS_QUERY(Sub)
1008   DEFINE_CLASS_QUERY(SubTypeCheck)
1009   DEFINE_CLASS_QUERY(Type)
1010   DEFINE_CLASS_QUERY(Vector)
1011   DEFINE_CLASS_QUERY(VectorMaskCmp)
1012   DEFINE_CLASS_QUERY(VectorUnbox)
1013   DEFINE_CLASS_QUERY(VectorReinterpret)
1014   DEFINE_CLASS_QUERY(CompressV)
1015   DEFINE_CLASS_QUERY(ExpandV)
1016   DEFINE_CLASS_QUERY(CompressM)
1017   DEFINE_CLASS_QUERY(LoadVector)
1018   DEFINE_CLASS_QUERY(LoadVectorGather)
1019   DEFINE_CLASS_QUERY(LoadVectorMasked)
1020   DEFINE_CLASS_QUERY(LoadVectorGatherMasked)
1021   DEFINE_CLASS_QUERY(StoreVector)
1022   DEFINE_CLASS_QUERY(StoreVectorScatter)
1023   DEFINE_CLASS_QUERY(StoreVectorMasked)
1024   DEFINE_CLASS_QUERY(StoreVectorScatterMasked)
1025   DEFINE_CLASS_QUERY(SaturatingVector)
1026   DEFINE_CLASS_QUERY(ShiftV)
1027   DEFINE_CLASS_QUERY(Unlock)
1028 
1029   #undef DEFINE_CLASS_QUERY
1030 
1031   // duplicate of is_MachSpillCopy()
1032   bool is_SpillCopy () const {
1033     return ((_class_id & ClassMask_MachSpillCopy) == Class_MachSpillCopy);
1034   }
1035 
1036   bool is_Con () const { return (_flags & Flag_is_Con) != 0; }
1037   // The data node which is safe to leave in dead loop during IGVN optimization.
1038   bool is_dead_loop_safe() const;
1039 
1040   // is_Copy() returns copied edge index (0 or 1)
1041   uint is_Copy() const { return (_flags & Flag_is_Copy); }
1042 
1043   virtual bool is_CFG() const { return false; }
1044 
1045   // If this node is control-dependent on a test, can it be
1046   // rerouted to a dominating equivalent test?  This is usually
1047   // true of non-CFG nodes, but can be false for operations which
1048   // depend for their correct sequencing on more than one test.
1049   // (In that case, hoisting to a dominating test may silently
1050   // skip some other important test.)
1051   virtual bool depends_only_on_test() const { assert(!is_CFG(), ""); return true; };
1052 
1053   // When building basic blocks, I need to have a notion of block beginning
1054   // Nodes, next block selector Nodes (block enders), and next block
1055   // projections.  These calls need to work on their machine equivalents.  The
1056   // Ideal beginning Nodes are RootNode, RegionNode and StartNode.
1057   bool is_block_start() const {
1058     if ( is_Region() )
1059       return this == (const Node*)in(0);
1060     else
1061       return is_Start();
1062   }
1063 
1064   // The Ideal control projection Nodes are IfTrue/IfFalse, JumpProjNode, Root,
1065   // Goto and Return.  This call also returns the block ending Node.
1066   virtual const Node *is_block_proj() const;
1067 
1068   // The node is a "macro" node which needs to be expanded before matching
1069   bool is_macro() const { return (_flags & Flag_is_macro) != 0; }
1070   // The node is expensive: the best control is set during loop opts
1071   bool is_expensive() const { return (_flags & Flag_is_expensive) != 0 && in(0) != nullptr; }
1072   // The node's original edge position is swapped.
1073   bool has_swapped_edges() const { return (_flags & Flag_has_swapped_edges) != 0; }
1074 
1075   bool is_predicated_vector() const { return (_flags & Flag_is_predicated_vector) != 0; }
1076 
1077   bool is_predicated_using_blend() const { return (_flags & Flag_is_predicated_using_blend) != 0; }
1078 
1079   // Used in lcm to mark nodes that have scheduled
1080   bool is_scheduled() const { return (_flags & Flag_is_scheduled) != 0; }
1081 
1082   bool for_post_loop_opts_igvn() const { return (_flags & Flag_for_post_loop_opts_igvn) != 0; }
1083   bool for_merge_stores_igvn() const { return (_flags & Flag_for_merge_stores_igvn) != 0; }
1084 
1085   // Is 'n' possibly a loop entry (i.e. a Parse Predicate projection)?
1086   static bool may_be_loop_entry(Node* n) {
1087     return n != nullptr && n->is_IfProj() && n->in(0)->is_ParsePredicate();
1088   }
1089 
1090 //----------------- Optimization
1091 
1092   // Get the worst-case Type output for this Node.
1093   virtual const class Type *bottom_type() const;
1094 
1095   // If we find a better type for a node, try to record it permanently.
1096   // Return true if this node actually changed.
1097   // Be sure to do the hash_delete game in the "rehash" variant.
1098   void raise_bottom_type(const Type* new_type);
1099 
1100   // Get the address type with which this node uses and/or defs memory,
1101   // or null if none.  The address type is conservatively wide.
1102   // Returns non-null for calls, membars, loads, stores, etc.
1103   // Returns TypePtr::BOTTOM if the node touches memory "broadly".
1104   virtual const class TypePtr *adr_type() const { return nullptr; }
1105 
1106   // Return an existing node which computes the same function as this node.
1107   // The optimistic combined algorithm requires this to return a Node which
1108   // is a small number of steps away (e.g., one of my inputs).
1109   virtual Node* Identity(PhaseGVN* phase);
1110 
1111   // Return the set of values this Node can take on at runtime.
1112   virtual const Type* Value(PhaseGVN* phase) const;
1113 
1114   // Return a node which is more "ideal" than the current node.
1115   // The invariants on this call are subtle.  If in doubt, read the
1116   // treatise in node.cpp above the default implementation AND TEST WITH
1117   // -XX:VerifyIterativeGVN=1
1118   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1119 
1120   // Some nodes have specific Ideal subgraph transformations only if they are
1121   // unique users of specific nodes. Such nodes should be put on IGVN worklist
1122   // for the transformations to happen.
1123   bool has_special_unique_user() const;
1124 
1125   // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1126   Node* find_exact_control(Node* ctrl);
1127 
1128   // Results of the dominance analysis.
1129   enum class DomResult {
1130     NotDominate,         // 'this' node does not dominate 'sub'.
1131     Dominate,            // 'this' node dominates or is equal to 'sub'.
1132     EncounteredDeadCode  // Result is undefined due to encountering dead code.
1133   };
1134   // Check if 'this' node dominates or equal to 'sub'.
1135   DomResult dominates(Node* sub, Node_List &nlist);
1136 
1137   bool remove_dead_region(PhaseGVN *phase, bool can_reshape);
1138 public:
1139 
1140   // See if there is valid pipeline info
1141   static  const Pipeline *pipeline_class();
1142   virtual const Pipeline *pipeline() const;
1143 
1144   // Compute the latency from the def to this instruction of the ith input node
1145   uint latency(uint i);
1146 
1147   // Hash & compare functions, for pessimistic value numbering
1148 
1149   // If the hash function returns the special sentinel value NO_HASH,
1150   // the node is guaranteed never to compare equal to any other node.
1151   // If we accidentally generate a hash with value NO_HASH the node
1152   // won't go into the table and we'll lose a little optimization.
1153   static const uint NO_HASH = 0;
1154   virtual uint hash() const;
1155   virtual bool cmp( const Node &n ) const;
1156 
1157   // Operation appears to be iteratively computed (such as an induction variable)
1158   // It is possible for this operation to return false for a loop-varying
1159   // value, if it appears (by local graph inspection) to be computed by a simple conditional.
1160   bool is_iteratively_computed();
1161 
1162   // Determine if a node is a counted loop induction variable.
1163   // NOTE: The method is defined in "loopnode.cpp".
1164   bool is_cloop_ind_var() const;
1165 
1166   // Return a node with opcode "opc" and same inputs as "this" if one can
1167   // be found; Otherwise return null;
1168   Node* find_similar(int opc);
1169 
1170   // Return the unique control out if only one. Null if none or more than one.
1171   Node* unique_ctrl_out_or_null() const;
1172   // Return the unique control out. Asserts if none or more than one control out.
1173   Node* unique_ctrl_out() const;
1174 
1175   // Set control or add control as precedence edge
1176   void ensure_control_or_add_prec(Node* c);
1177   void add_prec_from(Node* n);
1178 
1179   // Visit boundary uses of the node and apply a callback function for each.
1180   // Recursively traverse uses, stopping and applying the callback when
1181   // reaching a boundary node, defined by is_boundary. Note: the function
1182   // definition appears after the complete type definition of Node_List.
1183   template <typename Callback, typename Check>
1184   void visit_uses(Callback callback, Check is_boundary) const;
1185 
1186   // Returns a clone of the current node that's pinned (if the current node is not) for nodes found in array accesses
1187   // (Load and range check CastII nodes).
1188   // This is used when an array access is made dependent on 2 or more range checks (range check smearing or Loop Predication).
1189   virtual Node* pin_array_access_node() const {
1190     return nullptr;
1191   }
1192 
1193   //----------------- Code Generation
1194 
1195   // Ideal register class for Matching.  Zero means unmatched instruction
1196   // (these are cloned instead of converted to machine nodes).
1197   virtual uint ideal_reg() const;
1198 
1199   static const uint NotAMachineReg;   // must be > max. machine register
1200 
1201   // Do we Match on this edge index or not?  Generally false for Control
1202   // and true for everything else.  Weird for calls & returns.
1203   virtual uint match_edge(uint idx) const;
1204 
1205   // Register class output is returned in
1206   virtual const RegMask &out_RegMask() const;
1207   // Register class input is expected in
1208   virtual const RegMask &in_RegMask(uint) const;
1209   // Should we clone rather than spill this instruction?
1210   bool rematerialize() const;
1211 
1212   // Return JVM State Object if this Node carries debug info, or null otherwise
1213   virtual JVMState* jvms() const;
1214 
1215   // Print as assembly
1216   virtual void format( PhaseRegAlloc *, outputStream* st = tty ) const;
1217   // Emit bytes using C2_MacroAssembler
1218   virtual void emit(C2_MacroAssembler *masm, PhaseRegAlloc *ra_) const;
1219   // Size of instruction in bytes
1220   virtual uint size(PhaseRegAlloc *ra_) const;
1221 
1222   // Convenience function to extract an integer constant from a node.
1223   // If it is not an integer constant (either Con, CastII, or Mach),
1224   // return value_if_unknown.
1225   jint find_int_con(jint value_if_unknown) const {
1226     const TypeInt* t = find_int_type();
1227     return (t != nullptr && t->is_con()) ? t->get_con() : value_if_unknown;
1228   }
1229   // Return the constant, knowing it is an integer constant already
1230   jint get_int() const {
1231     const TypeInt* t = find_int_type();
1232     guarantee(t != nullptr, "must be con");
1233     return t->get_con();
1234   }
1235   // Here's where the work is done.  Can produce non-constant int types too.
1236   const TypeInt* find_int_type() const;
1237   const TypeInteger* find_integer_type(BasicType bt) const;
1238 
1239   // Same thing for long (and intptr_t, via type.hpp):
1240   jlong get_long() const {
1241     const TypeLong* t = find_long_type();
1242     guarantee(t != nullptr, "must be con");
1243     return t->get_con();
1244   }
1245   jlong find_long_con(jint value_if_unknown) const {
1246     const TypeLong* t = find_long_type();
1247     return (t != nullptr && t->is_con()) ? t->get_con() : value_if_unknown;
1248   }
1249   const TypeLong* find_long_type() const;
1250 
1251   jlong get_integer_as_long(BasicType bt) const {
1252     const TypeInteger* t = find_integer_type(bt);
1253     guarantee(t != nullptr && t->is_con(), "must be con");
1254     return t->get_con_as_long(bt);
1255   }
1256   jlong find_integer_as_long(BasicType bt, jlong value_if_unknown) const {
1257     const TypeInteger* t = find_integer_type(bt);
1258     if (t == nullptr || !t->is_con())  return value_if_unknown;
1259     return t->get_con_as_long(bt);
1260   }
1261   const TypePtr* get_ptr_type() const;
1262 
1263   // These guys are called by code generated by ADLC:
1264   intptr_t get_ptr() const;
1265   intptr_t get_narrowcon() const;
1266   jdouble getd() const;
1267   jfloat getf() const;
1268   jshort geth() const;
1269 
1270   // Nodes which are pinned into basic blocks
1271   virtual bool pinned() const { return false; }
1272 
1273   // Nodes which use memory without consuming it, hence need antidependences
1274   // More specifically, needs_anti_dependence_check returns true iff the node
1275   // (a) does a load, and (b) does not perform a store (except perhaps to a
1276   // stack slot or some other unaliased location).
1277   bool needs_anti_dependence_check() const;
1278 
1279   // Return which operand this instruction may cisc-spill. In other words,
1280   // return operand position that can convert from reg to memory access
1281   virtual int cisc_operand() const { return AdlcVMDeps::Not_cisc_spillable; }
1282   bool is_cisc_alternate() const { return (_flags & Flag_is_cisc_alternate) != 0; }
1283 
1284   // Whether this is a memory-writing machine node.
1285   bool is_memory_writer() const { return is_Mach() && bottom_type()->has_memory(); }
1286 
1287   // Whether this is a memory phi node
1288   bool is_memory_phi() const { return is_Phi() && bottom_type() == Type::MEMORY; }
1289 
1290   bool is_div_or_mod(BasicType bt) const;
1291 
1292   bool is_pure_function() const;
1293 
1294   bool is_data_proj_of_pure_function(const Node* maybe_pure_function) const;
1295 
1296 //----------------- Printing, etc
1297 #ifndef PRODUCT
1298  public:
1299   Node* find(int idx, bool only_ctrl = false); // Search the graph for the given idx.
1300   Node* find_ctrl(int idx); // Search control ancestors for the given idx.
1301   void dump_bfs(const int max_distance, Node* target, const char* options, outputStream* st) const;
1302   void dump_bfs(const int max_distance, Node* target, const char* options) const; // directly to tty
1303   void dump_bfs(const int max_distance) const; // dump_bfs(max_distance, nullptr, nullptr)
1304   class DumpConfig {
1305    public:
1306     // overridden to implement coloring of node idx
1307     virtual void pre_dump(outputStream *st, const Node* n) = 0;
1308     virtual void post_dump(outputStream *st) = 0;
1309   };
1310   void dump_idx(bool align = false, outputStream* st = tty, DumpConfig* dc = nullptr) const;
1311   void dump_name(outputStream* st = tty, DumpConfig* dc = nullptr) const;
1312   void dump() const; // print node with newline
1313   void dump(const char* suffix, bool mark = false, outputStream* st = tty, DumpConfig* dc = nullptr) const; // Print this node.
1314   void dump(int depth) const;        // Print this node, recursively to depth d
1315   void dump_ctrl(int depth) const;   // Print control nodes, to depth d
1316   void dump_comp() const;            // Print this node in compact representation.
1317   // Print this node in compact representation.
1318   void dump_comp(const char* suffix, outputStream *st = tty) const;
1319  private:
1320   virtual void dump_req(outputStream* st = tty, DumpConfig* dc = nullptr) const;    // Print required-edge info
1321   virtual void dump_prec(outputStream* st = tty, DumpConfig* dc = nullptr) const;   // Print precedence-edge info
1322   virtual void dump_out(outputStream* st = tty, DumpConfig* dc = nullptr) const;    // Print the output edge info
1323  public:
1324   virtual void dump_spec(outputStream *st) const {};      // Print per-node info
1325   // Print compact per-node info
1326   virtual void dump_compact_spec(outputStream *st) const { dump_spec(st); }
1327 
1328   static void verify(int verify_depth, VectorSet& visited, Node_List& worklist);
1329 
1330   // This call defines a class-unique string used to identify class instances
1331   virtual const char *Name() const;
1332 
1333   void dump_format(PhaseRegAlloc *ra) const; // debug access to MachNode::format(...)
1334   static bool in_dump() { return Compile::current()->_in_dump_cnt > 0; } // check if we are in a dump call
1335 #endif
1336 #ifdef ASSERT
1337   void verify_construction();
1338   bool verify_jvms(const JVMState* jvms) const;
1339 
1340   Node* _debug_orig;                   // Original version of this, if any.
1341   Node*  debug_orig() const            { return _debug_orig; }
1342   void   set_debug_orig(Node* orig);   // _debug_orig = orig
1343   void   dump_orig(outputStream *st, bool print_key = true) const;
1344 
1345   uint64_t _debug_idx;                 // Unique value assigned to every node.
1346   uint64_t debug_idx() const           { return _debug_idx; }
1347   void set_debug_idx(uint64_t debug_idx) { _debug_idx = debug_idx; }
1348 
1349   int        _hash_lock;               // Barrier to modifications of nodes in the hash table
1350   void  enter_hash_lock() { ++_hash_lock; assert(_hash_lock < 99, "in too many hash tables?"); }
1351   void   exit_hash_lock() { --_hash_lock; assert(_hash_lock >= 0, "mispaired hash locks"); }
1352 
1353   static void init_NodeProperty();
1354 
1355   #if OPTO_DU_ITERATOR_ASSERT
1356   const Node* _last_del;               // The last deleted node.
1357   uint        _del_tick;               // Bumped when a deletion happens..
1358   #endif
1359 #endif
1360 };
1361 
1362 inline bool not_a_node(const Node* n) {
1363   if (n == nullptr)                return true;
1364   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
1365   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
1366   return false;
1367 }
1368 
1369 //-----------------------------------------------------------------------------
1370 // Iterators over DU info, and associated Node functions.
1371 
1372 #if OPTO_DU_ITERATOR_ASSERT
1373 
1374 // Common code for assertion checking on DU iterators.
1375 class DUIterator_Common {
1376 #ifdef ASSERT
1377  protected:
1378   bool         _vdui;               // cached value of VerifyDUIterators
1379   const Node*  _node;               // the node containing the _out array
1380   uint         _outcnt;             // cached node->_outcnt
1381   uint         _del_tick;           // cached node->_del_tick
1382   Node*        _last;               // last value produced by the iterator
1383 
1384   void sample(const Node* node);    // used by c'tor to set up for verifies
1385   void verify(const Node* node, bool at_end_ok = false);
1386   void verify_resync();
1387   void reset(const DUIterator_Common& that);
1388 
1389 // The VDUI_ONLY macro protects code conditionalized on VerifyDUIterators
1390   #define I_VDUI_ONLY(i,x) { if ((i)._vdui) { x; } }
1391 #else
1392   #define I_VDUI_ONLY(i,x) { }
1393 #endif //ASSERT
1394 };
1395 
1396 #define VDUI_ONLY(x)     I_VDUI_ONLY(*this, x)
1397 
1398 // Default DU iterator.  Allows appends onto the out array.
1399 // Allows deletion from the out array only at the current point.
1400 // Usage:
1401 //  for (DUIterator i = x->outs(); x->has_out(i); i++) {
1402 //    Node* y = x->out(i);
1403 //    ...
1404 //  }
1405 // Compiles in product mode to a unsigned integer index, which indexes
1406 // onto a repeatedly reloaded base pointer of x->_out.  The loop predicate
1407 // also reloads x->_outcnt.  If you delete, you must perform "--i" just
1408 // before continuing the loop.  You must delete only the last-produced
1409 // edge.  You must delete only a single copy of the last-produced edge,
1410 // or else you must delete all copies at once (the first time the edge
1411 // is produced by the iterator).
1412 class DUIterator : public DUIterator_Common {
1413   friend class Node;
1414 
1415   // This is the index which provides the product-mode behavior.
1416   // Whatever the product-mode version of the system does to the
1417   // DUI index is done to this index.  All other fields in
1418   // this class are used only for assertion checking.
1419   uint         _idx;
1420 
1421   #ifdef ASSERT
1422   uint         _refresh_tick;    // Records the refresh activity.
1423 
1424   void sample(const Node* node); // Initialize _refresh_tick etc.
1425   void verify(const Node* node, bool at_end_ok = false);
1426   void verify_increment();       // Verify an increment operation.
1427   void verify_resync();          // Verify that we can back up over a deletion.
1428   void verify_finish();          // Verify that the loop terminated properly.
1429   void refresh();                // Resample verification info.
1430   void reset(const DUIterator& that);  // Resample after assignment.
1431   #endif
1432 
1433   DUIterator(const Node* node, int dummy_to_avoid_conversion)
1434     { _idx = 0;                         debug_only(sample(node)); }
1435 
1436  public:
1437   // initialize to garbage; clear _vdui to disable asserts
1438   DUIterator()
1439     { /*initialize to garbage*/         debug_only(_vdui = false); }
1440 
1441   DUIterator(const DUIterator& that)
1442     { _idx = that._idx;                 debug_only(_vdui = false; reset(that)); }
1443 
1444   void operator++(int dummy_to_specify_postfix_op)
1445     { _idx++;                           VDUI_ONLY(verify_increment()); }
1446 
1447   void operator--()
1448     { VDUI_ONLY(verify_resync());       --_idx; }
1449 
1450   ~DUIterator()
1451     { VDUI_ONLY(verify_finish()); }
1452 
1453   void operator=(const DUIterator& that)
1454     { _idx = that._idx;                 debug_only(reset(that)); }
1455 };
1456 
1457 DUIterator Node::outs() const
1458   { return DUIterator(this, 0); }
1459 DUIterator& Node::refresh_out_pos(DUIterator& i) const
1460   { I_VDUI_ONLY(i, i.refresh());        return i; }
1461 bool Node::has_out(DUIterator& i) const
1462   { I_VDUI_ONLY(i, i.verify(this,true));return i._idx < _outcnt; }
1463 Node*    Node::out(DUIterator& i) const
1464   { I_VDUI_ONLY(i, i.verify(this));     return debug_only(i._last=) _out[i._idx]; }
1465 
1466 
1467 // Faster DU iterator.  Disallows insertions into the out array.
1468 // Allows deletion from the out array only at the current point.
1469 // Usage:
1470 //  for (DUIterator_Fast imax, i = x->fast_outs(imax); i < imax; i++) {
1471 //    Node* y = x->fast_out(i);
1472 //    ...
1473 //  }
1474 // Compiles in product mode to raw Node** pointer arithmetic, with
1475 // no reloading of pointers from the original node x.  If you delete,
1476 // you must perform "--i; --imax" just before continuing the loop.
1477 // If you delete multiple copies of the same edge, you must decrement
1478 // imax, but not i, multiple times:  "--i, imax -= num_edges".
1479 class DUIterator_Fast : public DUIterator_Common {
1480   friend class Node;
1481   friend class DUIterator_Last;
1482 
1483   // This is the pointer which provides the product-mode behavior.
1484   // Whatever the product-mode version of the system does to the
1485   // DUI pointer is done to this pointer.  All other fields in
1486   // this class are used only for assertion checking.
1487   Node**       _outp;
1488 
1489   #ifdef ASSERT
1490   void verify(const Node* node, bool at_end_ok = false);
1491   void verify_limit();
1492   void verify_resync();
1493   void verify_relimit(uint n);
1494   void reset(const DUIterator_Fast& that);
1495   #endif
1496 
1497   // Note:  offset must be signed, since -1 is sometimes passed
1498   DUIterator_Fast(const Node* node, ptrdiff_t offset)
1499     { _outp = node->_out + offset;      debug_only(sample(node)); }
1500 
1501  public:
1502   // initialize to garbage; clear _vdui to disable asserts
1503   DUIterator_Fast()
1504     { /*initialize to garbage*/         debug_only(_vdui = false); }
1505 
1506   DUIterator_Fast(const DUIterator_Fast& that)
1507     { _outp = that._outp;               debug_only(_vdui = false; reset(that)); }
1508 
1509   void operator++(int dummy_to_specify_postfix_op)
1510     { _outp++;                          VDUI_ONLY(verify(_node, true)); }
1511 
1512   void operator--()
1513     { VDUI_ONLY(verify_resync());       --_outp; }
1514 
1515   void operator-=(uint n)   // applied to the limit only
1516     { _outp -= n;           VDUI_ONLY(verify_relimit(n));  }
1517 
1518   bool operator<(DUIterator_Fast& limit) {
1519     I_VDUI_ONLY(*this, this->verify(_node, true));
1520     I_VDUI_ONLY(limit, limit.verify_limit());
1521     return _outp < limit._outp;
1522   }
1523 
1524   void operator=(const DUIterator_Fast& that)
1525     { _outp = that._outp;               debug_only(reset(that)); }
1526 };
1527 
1528 DUIterator_Fast Node::fast_outs(DUIterator_Fast& imax) const {
1529   // Assign a limit pointer to the reference argument:
1530   imax = DUIterator_Fast(this, (ptrdiff_t)_outcnt);
1531   // Return the base pointer:
1532   return DUIterator_Fast(this, 0);
1533 }
1534 Node* Node::fast_out(DUIterator_Fast& i) const {
1535   I_VDUI_ONLY(i, i.verify(this));
1536   return debug_only(i._last=) *i._outp;
1537 }
1538 
1539 
1540 // Faster DU iterator.  Requires each successive edge to be removed.
1541 // Does not allow insertion of any edges.
1542 // Usage:
1543 //  for (DUIterator_Last imin, i = x->last_outs(imin); i >= imin; i -= num_edges) {
1544 //    Node* y = x->last_out(i);
1545 //    ...
1546 //  }
1547 // Compiles in product mode to raw Node** pointer arithmetic, with
1548 // no reloading of pointers from the original node x.
1549 class DUIterator_Last : private DUIterator_Fast {
1550   friend class Node;
1551 
1552   #ifdef ASSERT
1553   void verify(const Node* node, bool at_end_ok = false);
1554   void verify_limit();
1555   void verify_step(uint num_edges);
1556   #endif
1557 
1558   // Note:  offset must be signed, since -1 is sometimes passed
1559   DUIterator_Last(const Node* node, ptrdiff_t offset)
1560     : DUIterator_Fast(node, offset) { }
1561 
1562   void operator++(int dummy_to_specify_postfix_op) {} // do not use
1563   void operator<(int)                              {} // do not use
1564 
1565  public:
1566   DUIterator_Last() { }
1567   // initialize to garbage
1568 
1569   DUIterator_Last(const DUIterator_Last& that) = default;
1570 
1571   void operator--()
1572     { _outp--;              VDUI_ONLY(verify_step(1));  }
1573 
1574   void operator-=(uint n)
1575     { _outp -= n;           VDUI_ONLY(verify_step(n));  }
1576 
1577   bool operator>=(DUIterator_Last& limit) {
1578     I_VDUI_ONLY(*this, this->verify(_node, true));
1579     I_VDUI_ONLY(limit, limit.verify_limit());
1580     return _outp >= limit._outp;
1581   }
1582 
1583   DUIterator_Last& operator=(const DUIterator_Last& that) = default;
1584 };
1585 
1586 DUIterator_Last Node::last_outs(DUIterator_Last& imin) const {
1587   // Assign a limit pointer to the reference argument:
1588   imin = DUIterator_Last(this, 0);
1589   // Return the initial pointer:
1590   return DUIterator_Last(this, (ptrdiff_t)_outcnt - 1);
1591 }
1592 Node* Node::last_out(DUIterator_Last& i) const {
1593   I_VDUI_ONLY(i, i.verify(this));
1594   return debug_only(i._last=) *i._outp;
1595 }
1596 
1597 #endif //OPTO_DU_ITERATOR_ASSERT
1598 
1599 #undef I_VDUI_ONLY
1600 #undef VDUI_ONLY
1601 
1602 // An Iterator that truly follows the iterator pattern.  Doesn't
1603 // support deletion but could be made to.
1604 //
1605 //   for (SimpleDUIterator i(n); i.has_next(); i.next()) {
1606 //     Node* m = i.get();
1607 //
1608 class SimpleDUIterator : public StackObj {
1609  private:
1610   Node* node;
1611   DUIterator_Fast imax;
1612   DUIterator_Fast i;
1613  public:
1614   SimpleDUIterator(Node* n): node(n), i(n->fast_outs(imax)) {}
1615   bool has_next() { return i < imax; }
1616   void next() { i++; }
1617   Node* get() { return node->fast_out(i); }
1618 };
1619 
1620 
1621 //-----------------------------------------------------------------------------
1622 // Map dense integer indices to Nodes.  Uses classic doubling-array trick.
1623 // Abstractly provides an infinite array of Node*'s, initialized to null.
1624 // Note that the constructor just zeros things, and since I use Arena
1625 // allocation I do not need a destructor to reclaim storage.
1626 class Node_Array : public AnyObj {
1627 protected:
1628   Arena* _a;                    // Arena to allocate in
1629   uint   _max;
1630   Node** _nodes;
1631   ReallocMark _nesting;         // Safety checks for arena reallocation
1632 
1633   // Grow array to required capacity
1634   void maybe_grow(uint i) {
1635     if (i >= _max) {
1636       grow(i);
1637     }
1638   }
1639   void grow(uint i);
1640 
1641 public:
1642   Node_Array(Arena* a, uint max = OptoNodeListSize) : _a(a), _max(max) {
1643     _nodes = NEW_ARENA_ARRAY(a, Node*, max);
1644     clear();
1645   }
1646   Node_Array() : Node_Array(Thread::current()->resource_area()) {}
1647 
1648   NONCOPYABLE(Node_Array);
1649   Node_Array& operator=(Node_Array&&) = delete;
1650   // Allow move constructor for && (eg. capture return of function)
1651   Node_Array(Node_Array&&) = default;
1652 
1653   Node *operator[] ( uint i ) const // Lookup, or null for not mapped
1654   { return (i<_max) ? _nodes[i] : (Node*)nullptr; }
1655   Node* at(uint i) const { assert(i<_max,"oob"); return _nodes[i]; }
1656   Node** adr() { return _nodes; }
1657   // Extend the mapping: index i maps to Node *n.
1658   void map( uint i, Node *n ) { maybe_grow(i); _nodes[i] = n; }
1659   void insert( uint i, Node *n );
1660   void remove( uint i );        // Remove, preserving order
1661   // Clear all entries in _nodes to null but keep storage
1662   void clear() {
1663     Copy::zero_to_bytes(_nodes, _max * sizeof(Node*));
1664   }
1665 
1666   uint max() const { return _max; }
1667   void dump() const;
1668 };
1669 
1670 class Node_List : public Node_Array {
1671   uint _cnt;
1672 public:
1673   Node_List(uint max = OptoNodeListSize) : Node_Array(Thread::current()->resource_area(), max), _cnt(0) {}
1674   Node_List(Arena *a, uint max = OptoNodeListSize) : Node_Array(a, max), _cnt(0) {}
1675 
1676   NONCOPYABLE(Node_List);
1677   Node_List& operator=(Node_List&&) = delete;
1678   // Allow move constructor for && (eg. capture return of function)
1679   Node_List(Node_List&&) = default;
1680 
1681   bool contains(const Node* n) const {
1682     for (uint e = 0; e < size(); e++) {
1683       if (at(e) == n) return true;
1684     }
1685     return false;
1686   }
1687   void insert( uint i, Node *n ) { Node_Array::insert(i,n); _cnt++; }
1688   void remove( uint i ) { Node_Array::remove(i); _cnt--; }
1689   void push( Node *b ) { map(_cnt++,b); }
1690   void yank( Node *n );         // Find and remove
1691   Node *pop() { return _nodes[--_cnt]; }
1692   void clear() { _cnt = 0; Node_Array::clear(); } // retain storage
1693   void copy(const Node_List& from) {
1694     if (from._max > _max) {
1695       grow(from._max);
1696     }
1697     _cnt = from._cnt;
1698     Copy::conjoint_words_to_higher((HeapWord*)&from._nodes[0], (HeapWord*)&_nodes[0], from._max * sizeof(Node*));
1699   }
1700 
1701   uint size() const { return _cnt; }
1702   void dump() const;
1703   void dump_simple() const;
1704 };
1705 
1706 // Definition must appear after complete type definition of Node_List
1707 template <typename Callback, typename Check>
1708 void Node::visit_uses(Callback callback, Check is_boundary) const {
1709   ResourceMark rm;
1710   VectorSet visited;
1711   Node_List worklist;
1712 
1713   // The initial worklist consists of the direct uses
1714   for (DUIterator_Fast kmax, k = fast_outs(kmax); k < kmax; k++) {
1715     Node* out = fast_out(k);
1716     if (!visited.test_set(out->_idx)) { worklist.push(out); }
1717   }
1718 
1719   while (worklist.size() > 0) {
1720     Node* use = worklist.pop();
1721     // Apply callback on boundary nodes
1722     if (is_boundary(use)) {
1723       callback(use);
1724     } else {
1725       // Not a boundary node, continue search
1726       for (DUIterator_Fast kmax, k = use->fast_outs(kmax); k < kmax; k++) {
1727         Node* out = use->fast_out(k);
1728         if (!visited.test_set(out->_idx)) { worklist.push(out); }
1729       }
1730     }
1731   }
1732 }
1733 
1734 
1735 //------------------------------Unique_Node_List-------------------------------
1736 class Unique_Node_List : public Node_List {
1737   VectorSet _in_worklist;
1738   uint _clock_index;            // Index in list where to pop from next
1739 public:
1740   Unique_Node_List() : Node_List(), _clock_index(0) {}
1741   Unique_Node_List(Arena *a) : Node_List(a), _in_worklist(a), _clock_index(0) {}
1742 
1743   NONCOPYABLE(Unique_Node_List);
1744   Unique_Node_List& operator=(Unique_Node_List&&) = delete;
1745   // Allow move constructor for && (eg. capture return of function)
1746   Unique_Node_List(Unique_Node_List&&) = default;
1747 
1748   void remove( Node *n );
1749   bool member(const Node* n) const { return _in_worklist.test(n->_idx) != 0; }
1750   VectorSet& member_set(){ return _in_worklist; }
1751 
1752   void push(Node* b) {
1753     if( !_in_worklist.test_set(b->_idx) )
1754       Node_List::push(b);
1755   }
1756   void push_non_cfg_inputs_of(const Node* node) {
1757     for (uint i = 1; i < node->req(); i++) {
1758       Node* input = node->in(i);
1759       if (input != nullptr && !input->is_CFG()) {
1760         push(input);
1761       }
1762     }
1763   }
1764 
1765   void push_outputs_of(const Node* node) {
1766     for (DUIterator_Fast imax, i = node->fast_outs(imax); i < imax; i++) {
1767       Node* output = node->fast_out(i);
1768       push(output);
1769     }
1770   }
1771 
1772   Node *pop() {
1773     if( _clock_index >= size() ) _clock_index = 0;
1774     Node *b = at(_clock_index);
1775     map( _clock_index, Node_List::pop());
1776     if (size() != 0) _clock_index++; // Always start from 0
1777     _in_worklist.remove(b->_idx);
1778     return b;
1779   }
1780   Node *remove(uint i) {
1781     Node *b = Node_List::at(i);
1782     _in_worklist.remove(b->_idx);
1783     map(i,Node_List::pop());
1784     return b;
1785   }
1786   void yank(Node *n) {
1787     _in_worklist.remove(n->_idx);
1788     Node_List::yank(n);
1789   }
1790   void  clear() {
1791     _in_worklist.clear();        // Discards storage but grows automatically
1792     Node_List::clear();
1793     _clock_index = 0;
1794   }
1795   void ensure_empty() {
1796     assert(size() == 0, "must be empty");
1797     clear(); // just in case
1798   }
1799 
1800   // Used after parsing to remove useless nodes before Iterative GVN
1801   void remove_useless_nodes(VectorSet& useful);
1802 
1803   // If the idx of the Nodes change, we must recompute the VectorSet
1804   void recompute_idx_set() {
1805     _in_worklist.clear();
1806     for (uint i = 0; i < size(); i++) {
1807       Node* n = at(i);
1808       _in_worklist.set(n->_idx);
1809     }
1810   }
1811 
1812 #ifdef ASSERT
1813   bool is_subset_of(Unique_Node_List& other) {
1814     for (uint i = 0; i < size(); i++) {
1815       Node* n = at(i);
1816       if (!other.member(n)) {
1817         return false;
1818       }
1819     }
1820     return true;
1821   }
1822 #endif
1823 
1824   bool contains(const Node* n) const {
1825     fatal("use faster member() instead");
1826     return false;
1827   }
1828 
1829 #ifndef PRODUCT
1830   void print_set() const { _in_worklist.print(); }
1831 #endif
1832 };
1833 
1834 // Unique_Mixed_Node_List
1835 // unique: nodes are added only once
1836 // mixed: allow new and old nodes
1837 class Unique_Mixed_Node_List : public ResourceObj {
1838 public:
1839   Unique_Mixed_Node_List() : _visited_set(cmpkey, hashkey) {}
1840 
1841   void add(Node* node) {
1842     if (not_a_node(node)) {
1843       return; // Gracefully handle null, -1, 0xabababab, etc.
1844     }
1845     if (_visited_set[node] == nullptr) {
1846       _visited_set.Insert(node, node);
1847       _worklist.push(node);
1848     }
1849   }
1850 
1851   Node* operator[] (uint i) const {
1852     return _worklist[i];
1853   }
1854 
1855   size_t size() {
1856     return _worklist.size();
1857   }
1858 
1859 private:
1860   Dict _visited_set;
1861   Node_List _worklist;
1862 };
1863 
1864 // Inline definition of Compile::record_for_igvn must be deferred to this point.
1865 inline void Compile::record_for_igvn(Node* n) {
1866   _igvn_worklist->push(n);
1867 }
1868 
1869 // Inline definition of Compile::remove_for_igvn must be deferred to this point.
1870 inline void Compile::remove_for_igvn(Node* n) {
1871   _igvn_worklist->remove(n);
1872 }
1873 
1874 //------------------------------Node_Stack-------------------------------------
1875 class Node_Stack {
1876 protected:
1877   struct INode {
1878     Node *node; // Processed node
1879     uint  indx; // Index of next node's child
1880   };
1881   INode *_inode_top; // tos, stack grows up
1882   INode *_inode_max; // End of _inodes == _inodes + _max
1883   INode *_inodes;    // Array storage for the stack
1884   Arena *_a;         // Arena to allocate in
1885   ReallocMark _nesting; // Safety checks for arena reallocation
1886   void grow();
1887 public:
1888   Node_Stack(int size) {
1889     size_t max = (size > OptoNodeListSize) ? size : OptoNodeListSize;
1890     _a = Thread::current()->resource_area();
1891     _inodes = NEW_ARENA_ARRAY( _a, INode, max );
1892     _inode_max = _inodes + max;
1893     _inode_top = _inodes - 1; // stack is empty
1894   }
1895 
1896   Node_Stack(Arena *a, int size) : _a(a) {
1897     size_t max = (size > OptoNodeListSize) ? size : OptoNodeListSize;
1898     _inodes = NEW_ARENA_ARRAY( _a, INode, max );
1899     _inode_max = _inodes + max;
1900     _inode_top = _inodes - 1; // stack is empty
1901   }
1902 
1903   void pop() {
1904     assert(_inode_top >= _inodes, "node stack underflow");
1905     --_inode_top;
1906   }
1907   void push(Node *n, uint i) {
1908     ++_inode_top;
1909     grow();
1910     INode *top = _inode_top; // optimization
1911     top->node = n;
1912     top->indx = i;
1913   }
1914   Node *node() const {
1915     return _inode_top->node;
1916   }
1917   Node* node_at(uint i) const {
1918     assert(_inodes + i <= _inode_top, "in range");
1919     return _inodes[i].node;
1920   }
1921   uint index() const {
1922     return _inode_top->indx;
1923   }
1924   uint index_at(uint i) const {
1925     assert(_inodes + i <= _inode_top, "in range");
1926     return _inodes[i].indx;
1927   }
1928   void set_node(Node *n) {
1929     _inode_top->node = n;
1930   }
1931   void set_index(uint i) {
1932     _inode_top->indx = i;
1933   }
1934   uint size_max() const { return (uint)pointer_delta(_inode_max, _inodes,  sizeof(INode)); } // Max size
1935   uint size() const { return (uint)pointer_delta((_inode_top+1), _inodes,  sizeof(INode)); } // Current size
1936   bool is_nonempty() const { return (_inode_top >= _inodes); }
1937   bool is_empty() const { return (_inode_top < _inodes); }
1938   void clear() { _inode_top = _inodes - 1; } // retain storage
1939 
1940   // Node_Stack is used to map nodes.
1941   Node* find(uint idx) const;
1942 
1943   NONCOPYABLE(Node_Stack);
1944 };
1945 
1946 
1947 //-----------------------------Node_Notes--------------------------------------
1948 // Debugging or profiling annotations loosely and sparsely associated
1949 // with some nodes.  See Compile::node_notes_at for the accessor.
1950 class Node_Notes {
1951   JVMState* _jvms;
1952 
1953 public:
1954   Node_Notes(JVMState* jvms = nullptr) {
1955     _jvms = jvms;
1956   }
1957 
1958   JVMState* jvms()            { return _jvms; }
1959   void  set_jvms(JVMState* x) {        _jvms = x; }
1960 
1961   // True if there is nothing here.
1962   bool is_clear() {
1963     return (_jvms == nullptr);
1964   }
1965 
1966   // Make there be nothing here.
1967   void clear() {
1968     _jvms = nullptr;
1969   }
1970 
1971   // Make a new, clean node notes.
1972   static Node_Notes* make(Compile* C) {
1973     Node_Notes* nn = NEW_ARENA_ARRAY(C->comp_arena(), Node_Notes, 1);
1974     nn->clear();
1975     return nn;
1976   }
1977 
1978   Node_Notes* clone(Compile* C) {
1979     Node_Notes* nn = NEW_ARENA_ARRAY(C->comp_arena(), Node_Notes, 1);
1980     (*nn) = (*this);
1981     return nn;
1982   }
1983 
1984   // Absorb any information from source.
1985   bool update_from(Node_Notes* source) {
1986     bool changed = false;
1987     if (source != nullptr) {
1988       if (source->jvms() != nullptr) {
1989         set_jvms(source->jvms());
1990         changed = true;
1991       }
1992     }
1993     return changed;
1994   }
1995 };
1996 
1997 // Inlined accessors for Compile::node_nodes that require the preceding class:
1998 inline Node_Notes*
1999 Compile::locate_node_notes(GrowableArray<Node_Notes*>* arr,
2000                            int idx, bool can_grow) {
2001   assert(idx >= 0, "oob");
2002   int block_idx = (idx >> _log2_node_notes_block_size);
2003   int grow_by = (block_idx - (arr == nullptr? 0: arr->length()));
2004   if (grow_by >= 0) {
2005     if (!can_grow) return nullptr;
2006     grow_node_notes(arr, grow_by + 1);
2007   }
2008   if (arr == nullptr) return nullptr;
2009   // (Every element of arr is a sub-array of length _node_notes_block_size.)
2010   return arr->at(block_idx) + (idx & (_node_notes_block_size-1));
2011 }
2012 
2013 inline Node_Notes* Compile::node_notes_at(int idx) {
2014   return locate_node_notes(_node_note_array, idx, false);
2015 }
2016 
2017 inline bool
2018 Compile::set_node_notes_at(int idx, Node_Notes* value) {
2019   if (value == nullptr || value->is_clear())
2020     return false;  // nothing to write => write nothing
2021   Node_Notes* loc = locate_node_notes(_node_note_array, idx, true);
2022   assert(loc != nullptr, "");
2023   return loc->update_from(value);
2024 }
2025 
2026 
2027 //------------------------------TypeNode---------------------------------------
2028 // Node with a Type constant.
2029 class TypeNode : public Node {
2030 protected:
2031   virtual uint hash() const;    // Check the type
2032   virtual bool cmp( const Node &n ) const;
2033   virtual uint size_of() const; // Size is bigger
2034   const Type* const _type;
2035 public:
2036   void set_type(const Type* t) {
2037     assert(t != nullptr, "sanity");
2038     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
2039     *(const Type**)&_type = t;   // cast away const-ness
2040     // If this node is in the hash table, make sure it doesn't need a rehash.
2041     assert(check_hash == NO_HASH || check_hash == hash(), "type change must preserve hash code");
2042   }
2043   const Type* type() const { assert(_type != nullptr, "sanity"); return _type; };
2044   TypeNode( const Type *t, uint required ) : Node(required), _type(t) {
2045     init_class_id(Class_Type);
2046   }
2047   virtual const Type* Value(PhaseGVN* phase) const;
2048   virtual Node* Ideal(PhaseGVN* phase, bool can_reshape);
2049   virtual const Type *bottom_type() const;
2050   virtual       uint  ideal_reg() const;
2051 
2052   void make_path_dead(PhaseIterGVN* igvn, PhaseIdealLoop* loop, Node* ctrl_use, uint j, const char* phase_str);
2053 #ifndef PRODUCT
2054   virtual void dump_spec(outputStream *st) const;
2055   virtual void dump_compact_spec(outputStream *st) const;
2056 #endif
2057   void make_paths_from_here_dead(PhaseIterGVN* igvn, PhaseIdealLoop* loop, const char* phase_str);
2058   void create_halt_path(PhaseIterGVN* igvn, Node* c, PhaseIdealLoop* loop, const char* phase_str) const;
2059 };
2060 
2061 #include "opto/opcodes.hpp"
2062 
2063 #define Op_IL(op) \
2064   inline int Op_ ## op(BasicType bt) { \
2065   assert(bt == T_INT || bt == T_LONG, "only for int or longs"); \
2066   if (bt == T_INT) { \
2067     return Op_## op ## I; \
2068   } \
2069   return Op_## op ## L; \
2070 }
2071 
2072 Op_IL(Add)
2073 Op_IL(And)
2074 Op_IL(Sub)
2075 Op_IL(Mul)
2076 Op_IL(URShift)
2077 Op_IL(LShift)
2078 Op_IL(Xor)
2079 Op_IL(Cmp)
2080 Op_IL(Div)
2081 Op_IL(Mod)
2082 Op_IL(UDiv)
2083 Op_IL(UMod)
2084 
2085 inline int Op_ConIL(BasicType bt) {
2086   assert(bt == T_INT || bt == T_LONG, "only for int or longs");
2087   if (bt == T_INT) {
2088     return Op_ConI;
2089   }
2090   return Op_ConL;
2091 }
2092 
2093 inline int Op_Cmp_unsigned(BasicType bt) {
2094   assert(bt == T_INT || bt == T_LONG, "only for int or longs");
2095   if (bt == T_INT) {
2096     return Op_CmpU;
2097   }
2098   return Op_CmpUL;
2099 }
2100 
2101 inline int Op_Cast(BasicType bt) {
2102   assert(bt == T_INT || bt == T_LONG, "only for int or longs");
2103   if (bt == T_INT) {
2104     return Op_CastII;
2105   }
2106   return Op_CastLL;
2107 }
2108 
2109 inline int Op_DivIL(BasicType bt, bool is_unsigned) {
2110   assert(bt == T_INT || bt == T_LONG, "only for int or longs");
2111   if (bt == T_INT) {
2112     if (is_unsigned) {
2113       return Op_UDivI;
2114     } else {
2115       return Op_DivI;
2116     }
2117   }
2118   if (is_unsigned) {
2119     return Op_UDivL;
2120   } else {
2121     return Op_DivL;
2122   }
2123 }
2124 
2125 inline int Op_DivModIL(BasicType bt, bool is_unsigned) {
2126   assert(bt == T_INT || bt == T_LONG, "only for int or longs");
2127   if (bt == T_INT) {
2128     if (is_unsigned) {
2129       return Op_UDivModI;
2130     } else {
2131       return Op_DivModI;
2132     }
2133   }
2134   if (is_unsigned) {
2135     return Op_UDivModL;
2136   } else {
2137     return Op_DivModL;
2138   }
2139 }
2140 
2141 // Interface to define actions that should be taken when running DataNodeBFS. Each use can extend this class to specify
2142 // a customized BFS.
2143 class BFSActions : public StackObj {
2144  public:
2145   // Should a node's inputs further be visited in the BFS traversal? By default, we visit all data inputs. Override this
2146   // method to provide a custom filter.
2147   virtual bool should_visit(Node* node) const {
2148     // By default, visit all inputs.
2149     return true;
2150   };
2151 
2152   // Is the visited node a target node that we are looking for in the BFS traversal? We do not visit its inputs further
2153   // but the BFS will continue to visit all unvisited nodes in the queue.
2154   virtual bool is_target_node(Node* node) const = 0;
2155 
2156   // Defines an action that should be taken when we visit a target node in the BFS traversal.
2157   virtual void target_node_action(Node* target_node) = 0;
2158 };
2159 
2160 // Class to perform a BFS traversal on the data nodes from a given start node. The provided BFSActions guide which
2161 // data node's inputs should be further visited, which data nodes are target nodes and what to do with the target nodes.
2162 class DataNodeBFS : public StackObj {
2163   BFSActions& _bfs_actions;
2164 
2165  public:
2166   explicit DataNodeBFS(BFSActions& bfs_action) : _bfs_actions(bfs_action) {}
2167 
2168   // Run the BFS starting from 'start_node' and apply the actions provided to this class.
2169   void run(Node* start_node) {
2170     ResourceMark rm;
2171     Unique_Node_List _nodes_to_visit;
2172     _nodes_to_visit.push(start_node);
2173     for (uint i = 0; i < _nodes_to_visit.size(); i++) {
2174       Node* next = _nodes_to_visit[i];
2175       for (uint j = 1; j < next->req(); j++) {
2176         Node* input = next->in(j);
2177         if (_bfs_actions.is_target_node(input)) {
2178           assert(_bfs_actions.should_visit(input), "must also pass node filter");
2179           _bfs_actions.target_node_action(input);
2180         } else if (_bfs_actions.should_visit(input)) {
2181           _nodes_to_visit.push(input);
2182         }
2183       }
2184     }
2185   }
2186 };
2187 
2188 #endif // SHARE_OPTO_NODE_HPP