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.
   9  *
  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.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
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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 FlatArrayCheckNode;
  90 class HaltNode;
  91 class IfNode;
  92 class IfProjNode;
  93 class IfFalseNode;
  94 class IfTrueNode;
  95 class InitializeNode;
  96 class JVMState;
  97 class JumpNode;
  98 class JumpProjNode;
  99 class LoadNode;
 100 class LoadStoreNode;
 101 class LoadStoreConditionalNode;
 102 class LockNode;
 103 class LongCountedLoopNode;
 104 class LongCountedLoopEndNode;
 105 class LoopNode;
 106 class LShiftNode;
 107 class MachBranchNode;
 108 class MachCallDynamicJavaNode;
 109 class MachCallJavaNode;
 110 class MachCallLeafNode;
 111 class MachCallNode;
 112 class MachCallRuntimeNode;
 113 class MachCallStaticJavaNode;
 114 class MachConstantBaseNode;
 115 class MachConstantNode;
 116 class MachGotoNode;
 117 class MachIfNode;
 118 class MachJumpNode;
 119 class MachNode;
 120 class MachNullCheckNode;
 121 class MachProjNode;
 122 class MachPrologNode;
 123 class MachReturnNode;
 124 class MachSafePointNode;
 125 class MachSpillCopyNode;
 126 class MachTempNode;
 127 class MachMergeNode;
 128 class MachMemBarNode;
 129 class MachVEPNode;
 130 class Matcher;
 131 class MemBarNode;
 132 class MemBarStoreStoreNode;
 133 class MemNode;
 134 class MergeMemNode;
 135 class MoveNode;
 136 class MulNode;
 137 class MultiNode;
 138 class MultiBranchNode;
 139 class NegNode;
 140 class NegVNode;
 141 class NeverBranchNode;
 142 class Opaque1Node;
 143 class OpaqueLoopInitNode;
 144 class OpaqueLoopStrideNode;
 145 class OpaqueMultiversioningNode;
 146 class OpaqueNotNullNode;
 147 class OpaqueInitializedAssertionPredicateNode;
 148 class OpaqueTemplateAssertionPredicateNode;
 149 class OuterStripMinedLoopNode;
 150 class OuterStripMinedLoopEndNode;
 151 class Node;
 152 class Node_Array;
 153 class Node_List;
 154 class Node_Stack;
 155 class OopMap;
 156 class ParmNode;
 157 class ParsePredicateNode;
 158 class PCTableNode;
 159 class PhaseCCP;
 160 class PhaseGVN;
 161 class PhaseIterGVN;
 162 class PhaseRegAlloc;
 163 class PhaseTransform;
 164 class PhaseValues;
 165 class PhiNode;
 166 class Pipeline;
 167 class PopulateIndexNode;
 168 class ProjNode;
 169 class RangeCheckNode;
 170 class ReductionNode;
 171 class RegMask;
 172 class RegionNode;
 173 class RootNode;
 174 class SafePointNode;
 175 class SafePointScalarObjectNode;
 176 class SafePointScalarMergeNode;
 177 class SaturatingVectorNode;
 178 class StartNode;
 179 class State;
 180 class StoreNode;
 181 class SubNode;
 182 class SubTypeCheckNode;
 183 class Type;
 184 class TypeNode;
 185 class UnlockNode;
 186 class InlineTypeNode;
 187 class VectorNode;
 188 class LoadVectorNode;
 189 class LoadVectorMaskedNode;
 190 class StoreVectorMaskedNode;
 191 class LoadVectorGatherNode;
 192 class LoadVectorGatherMaskedNode;
 193 class StoreVectorNode;
 194 class StoreVectorScatterNode;
 195 class StoreVectorScatterMaskedNode;
 196 class VerifyVectorAlignmentNode;
 197 class VectorMaskCmpNode;
 198 class VectorUnboxNode;
 199 class VectorSet;
 200 class VectorReinterpretNode;
 201 class ShiftVNode;
 202 class MulVLNode;
 203 class ExpandVNode;
 204 class CompressVNode;
 205 class CompressMNode;
 206 class C2_MacroAssembler;
 207 
 208 
 209 #ifndef OPTO_DU_ITERATOR_ASSERT
 210 #ifdef ASSERT
 211 #define OPTO_DU_ITERATOR_ASSERT 1
 212 #else
 213 #define OPTO_DU_ITERATOR_ASSERT 0
 214 #endif
 215 #endif //OPTO_DU_ITERATOR_ASSERT
 216 
 217 #if OPTO_DU_ITERATOR_ASSERT
 218 class DUIterator;
 219 class DUIterator_Fast;
 220 class DUIterator_Last;
 221 #else
 222 typedef uint   DUIterator;
 223 typedef Node** DUIterator_Fast;
 224 typedef Node** DUIterator_Last;
 225 #endif
 226 
 227 typedef ResizeableResourceHashtable<Node*, Node*, AnyObj::RESOURCE_AREA, mtCompiler> OrigToNewHashtable;
 228 
 229 // Node Sentinel
 230 #define NodeSentinel (Node*)-1
 231 
 232 // Unknown count frequency
 233 #define COUNT_UNKNOWN (-1.0f)
 234 
 235 //------------------------------Node-------------------------------------------
 236 // Nodes define actions in the program.  They create values, which have types.
 237 // They are both vertices in a directed graph and program primitives.  Nodes
 238 // are labeled; the label is the "opcode", the primitive function in the lambda
 239 // calculus sense that gives meaning to the Node.  Node inputs are ordered (so
 240 // that "a-b" is different from "b-a").  The inputs to a Node are the inputs to
 241 // the Node's function.  These inputs also define a Type equation for the Node.
 242 // Solving these Type equations amounts to doing dataflow analysis.
 243 // Control and data are uniformly represented in the graph.  Finally, Nodes
 244 // have a unique dense integer index which is used to index into side arrays
 245 // whenever I have phase-specific information.
 246 
 247 class Node {
 248 
 249   // Lots of restrictions on cloning Nodes
 250   NONCOPYABLE(Node);
 251 
 252 public:
 253   friend class Compile;
 254   #if OPTO_DU_ITERATOR_ASSERT
 255   friend class DUIterator_Common;
 256   friend class DUIterator;
 257   friend class DUIterator_Fast;
 258   friend class DUIterator_Last;
 259   #endif
 260 
 261   // Because Nodes come and go, I define an Arena of Node structures to pull
 262   // from.  This should allow fast access to node creation & deletion.  This
 263   // field is a local cache of a value defined in some "program fragment" for
 264   // which these Nodes are just a part of.
 265 
 266   inline void* operator new(size_t x) throw() {
 267     Compile* C = Compile::current();
 268     Node* n = (Node*)C->node_arena()->AmallocWords(x);
 269     return (void*)n;
 270   }
 271 
 272   // Delete is a NOP
 273   void operator delete( void *ptr ) {}
 274   // Fancy destructor; eagerly attempt to reclaim Node numberings and storage
 275   void destruct(PhaseValues* phase);
 276 
 277   // Create a new Node.  Required is the number is of inputs required for
 278   // semantic correctness.
 279   Node( uint required );
 280 
 281   // Create a new Node with given input edges.
 282   // This version requires use of the "edge-count" new.
 283   // E.g.  new (C,3) FooNode( C, nullptr, left, right );
 284   Node( Node *n0 );
 285   Node( Node *n0, Node *n1 );
 286   Node( Node *n0, Node *n1, Node *n2 );
 287   Node( Node *n0, Node *n1, Node *n2, Node *n3 );
 288   Node( Node *n0, Node *n1, Node *n2, Node *n3, Node *n4 );
 289   Node( Node *n0, Node *n1, Node *n2, Node *n3, Node *n4, Node *n5 );
 290   Node( Node *n0, Node *n1, Node *n2, Node *n3,
 291             Node *n4, Node *n5, Node *n6 );
 292 
 293   // Clone an inherited Node given only the base Node type.
 294   Node* clone() const;
 295 
 296   // Clone a Node, immediately supplying one or two new edges.
 297   // The first and second arguments, if non-null, replace in(1) and in(2),
 298   // respectively.
 299   Node* clone_with_data_edge(Node* in1, Node* in2 = nullptr) const {
 300     Node* nn = clone();
 301     if (in1 != nullptr)  nn->set_req(1, in1);
 302     if (in2 != nullptr)  nn->set_req(2, in2);
 303     return nn;
 304   }
 305 
 306 private:
 307   // Shared setup for the above constructors.
 308   // Handles all interactions with Compile::current.
 309   // Puts initial values in all Node fields except _idx.
 310   // Returns the initial value for _idx, which cannot
 311   // be initialized by assignment.
 312   inline int Init(int req);
 313 
 314 //----------------- input edge handling
 315 protected:
 316   friend class PhaseCFG;        // Access to address of _in array elements
 317   Node **_in;                   // Array of use-def references to Nodes
 318   Node **_out;                  // Array of def-use references to Nodes
 319 
 320   // Input edges are split into two categories.  Required edges are required
 321   // for semantic correctness; order is important and nulls are allowed.
 322   // Precedence edges are used to help determine execution order and are
 323   // added, e.g., for scheduling purposes.  They are unordered and not
 324   // duplicated; they have no embedded nulls.  Edges from 0 to _cnt-1
 325   // are required, from _cnt to _max-1 are precedence edges.
 326   node_idx_t _cnt;              // Total number of required Node inputs.
 327 
 328   node_idx_t _max;              // Actual length of input array.
 329 
 330   // Output edges are an unordered list of def-use edges which exactly
 331   // correspond to required input edges which point from other nodes
 332   // to this one.  Thus the count of the output edges is the number of
 333   // users of this node.
 334   node_idx_t _outcnt;           // Total number of Node outputs.
 335 
 336   node_idx_t _outmax;           // Actual length of output array.
 337 
 338   // Grow the actual input array to the next larger power-of-2 bigger than len.
 339   void grow( uint len );
 340   // Grow the output array to the next larger power-of-2 bigger than len.
 341   void out_grow( uint len );
 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         DEFINE_CLASS_ID(Blackhole,        MemBar, 2)
 699 
 700     DEFINE_CLASS_ID(Mach,  Node, 1)
 701       DEFINE_CLASS_ID(MachReturn, Mach, 0)
 702         DEFINE_CLASS_ID(MachSafePoint, MachReturn, 0)
 703           DEFINE_CLASS_ID(MachCall, MachSafePoint, 0)
 704             DEFINE_CLASS_ID(MachCallJava,         MachCall, 0)
 705               DEFINE_CLASS_ID(MachCallStaticJava,   MachCallJava, 0)
 706               DEFINE_CLASS_ID(MachCallDynamicJava,  MachCallJava, 1)
 707             DEFINE_CLASS_ID(MachCallRuntime,      MachCall, 1)
 708               DEFINE_CLASS_ID(MachCallLeaf,         MachCallRuntime, 0)
 709       DEFINE_CLASS_ID(MachBranch, Mach, 1)
 710         DEFINE_CLASS_ID(MachIf,         MachBranch, 0)
 711         DEFINE_CLASS_ID(MachGoto,       MachBranch, 1)
 712         DEFINE_CLASS_ID(MachNullCheck,  MachBranch, 2)
 713       DEFINE_CLASS_ID(MachSpillCopy,    Mach, 2)
 714       DEFINE_CLASS_ID(MachTemp,         Mach, 3)
 715       DEFINE_CLASS_ID(MachConstantBase, Mach, 4)
 716       DEFINE_CLASS_ID(MachConstant,     Mach, 5)
 717         DEFINE_CLASS_ID(MachJump,       MachConstant, 0)
 718       DEFINE_CLASS_ID(MachMerge,        Mach, 6)
 719       DEFINE_CLASS_ID(MachMemBar,       Mach, 7)
 720       DEFINE_CLASS_ID(MachProlog,       Mach, 8)
 721       DEFINE_CLASS_ID(MachVEP,          Mach, 9)
 722 
 723     DEFINE_CLASS_ID(Type,  Node, 2)
 724       DEFINE_CLASS_ID(Phi,   Type, 0)
 725       DEFINE_CLASS_ID(ConstraintCast, Type, 1)
 726         DEFINE_CLASS_ID(CastII, ConstraintCast, 0)
 727         DEFINE_CLASS_ID(CheckCastPP, ConstraintCast, 1)
 728         DEFINE_CLASS_ID(CastLL, ConstraintCast, 2)
 729         DEFINE_CLASS_ID(CastFF, ConstraintCast, 3)
 730         DEFINE_CLASS_ID(CastDD, ConstraintCast, 4)
 731         DEFINE_CLASS_ID(CastVV, ConstraintCast, 5)
 732         DEFINE_CLASS_ID(CastPP, ConstraintCast, 6)
 733         DEFINE_CLASS_ID(CastHH, ConstraintCast, 7)
 734       DEFINE_CLASS_ID(CMove, Type, 3)
 735       DEFINE_CLASS_ID(SafePointScalarObject, Type, 4)
 736       DEFINE_CLASS_ID(DecodeNarrowPtr, Type, 5)
 737         DEFINE_CLASS_ID(DecodeN, DecodeNarrowPtr, 0)
 738         DEFINE_CLASS_ID(DecodeNKlass, DecodeNarrowPtr, 1)
 739       DEFINE_CLASS_ID(EncodeNarrowPtr, Type, 6)
 740         DEFINE_CLASS_ID(EncodeP, EncodeNarrowPtr, 0)
 741         DEFINE_CLASS_ID(EncodePKlass, EncodeNarrowPtr, 1)
 742       DEFINE_CLASS_ID(Vector, Type, 7)
 743         DEFINE_CLASS_ID(VectorMaskCmp, Vector, 0)
 744         DEFINE_CLASS_ID(VectorUnbox, Vector, 1)
 745         DEFINE_CLASS_ID(VectorReinterpret, Vector, 2)
 746         DEFINE_CLASS_ID(ShiftV, Vector, 3)
 747         DEFINE_CLASS_ID(CompressV, Vector, 4)
 748         DEFINE_CLASS_ID(ExpandV, Vector, 5)
 749         DEFINE_CLASS_ID(CompressM, Vector, 6)
 750         DEFINE_CLASS_ID(Reduction, Vector, 7)
 751         DEFINE_CLASS_ID(NegV, Vector, 8)
 752         DEFINE_CLASS_ID(SaturatingVector, Vector, 9)
 753         DEFINE_CLASS_ID(MulVL, Vector, 10)
 754       DEFINE_CLASS_ID(InlineType, Type, 8)
 755       DEFINE_CLASS_ID(Con, Type, 9)
 756           DEFINE_CLASS_ID(ConI, Con, 0)
 757       DEFINE_CLASS_ID(SafePointScalarMerge, Type, 10)
 758       DEFINE_CLASS_ID(Convert, Type, 11)
 759 
 760 
 761     DEFINE_CLASS_ID(Proj,  Node, 3)
 762       DEFINE_CLASS_ID(CatchProj, Proj, 0)
 763       DEFINE_CLASS_ID(JumpProj,  Proj, 1)
 764       DEFINE_CLASS_ID(IfProj,    Proj, 2)
 765         DEFINE_CLASS_ID(IfTrue,    IfProj, 0)
 766         DEFINE_CLASS_ID(IfFalse,   IfProj, 1)
 767       DEFINE_CLASS_ID(Parm,      Proj, 4)
 768       DEFINE_CLASS_ID(MachProj,  Proj, 5)
 769 
 770     DEFINE_CLASS_ID(Mem, Node, 4)
 771       DEFINE_CLASS_ID(Load, Mem, 0)
 772         DEFINE_CLASS_ID(LoadVector,  Load, 0)
 773           DEFINE_CLASS_ID(LoadVectorGather, LoadVector, 0)
 774           DEFINE_CLASS_ID(LoadVectorGatherMasked, LoadVector, 1)
 775           DEFINE_CLASS_ID(LoadVectorMasked, LoadVector, 2)
 776       DEFINE_CLASS_ID(Store, Mem, 1)
 777         DEFINE_CLASS_ID(StoreVector, Store, 0)
 778           DEFINE_CLASS_ID(StoreVectorScatter, StoreVector, 0)
 779           DEFINE_CLASS_ID(StoreVectorScatterMasked, StoreVector, 1)
 780           DEFINE_CLASS_ID(StoreVectorMasked, StoreVector, 2)
 781       DEFINE_CLASS_ID(LoadStore, Mem, 2)
 782         DEFINE_CLASS_ID(LoadStoreConditional, LoadStore, 0)
 783           DEFINE_CLASS_ID(CompareAndSwap, LoadStoreConditional, 0)
 784         DEFINE_CLASS_ID(CompareAndExchangeNode, LoadStore, 1)
 785 
 786     DEFINE_CLASS_ID(Region, Node, 5)
 787       DEFINE_CLASS_ID(Loop, Region, 0)
 788         DEFINE_CLASS_ID(Root,                Loop, 0)
 789         DEFINE_CLASS_ID(BaseCountedLoop,     Loop, 1)
 790           DEFINE_CLASS_ID(CountedLoop,       BaseCountedLoop, 0)
 791           DEFINE_CLASS_ID(LongCountedLoop,   BaseCountedLoop, 1)
 792         DEFINE_CLASS_ID(OuterStripMinedLoop, Loop, 2)
 793 
 794     DEFINE_CLASS_ID(Sub,   Node, 6)
 795       DEFINE_CLASS_ID(Cmp,   Sub, 0)
 796         DEFINE_CLASS_ID(FastLock,       Cmp, 0)
 797         DEFINE_CLASS_ID(FastUnlock,     Cmp, 1)
 798         DEFINE_CLASS_ID(SubTypeCheck,   Cmp, 2)
 799         DEFINE_CLASS_ID(FlatArrayCheck, Cmp, 3)
 800 
 801     DEFINE_CLASS_ID(MergeMem, Node, 7)
 802     DEFINE_CLASS_ID(Bool,     Node, 8)
 803     DEFINE_CLASS_ID(AddP,     Node, 9)
 804     DEFINE_CLASS_ID(BoxLock,  Node, 10)
 805     DEFINE_CLASS_ID(Add,      Node, 11)
 806     DEFINE_CLASS_ID(Mul,      Node, 12)
 807     DEFINE_CLASS_ID(ClearArray, Node, 14)
 808     DEFINE_CLASS_ID(Halt,     Node, 15)
 809     DEFINE_CLASS_ID(Opaque1,  Node, 16)
 810       DEFINE_CLASS_ID(OpaqueLoopInit, Opaque1, 0)
 811       DEFINE_CLASS_ID(OpaqueLoopStride, Opaque1, 1)
 812       DEFINE_CLASS_ID(OpaqueMultiversioning, Opaque1, 2)
 813     DEFINE_CLASS_ID(OpaqueNotNull,  Node, 17)
 814     DEFINE_CLASS_ID(OpaqueInitializedAssertionPredicate,  Node, 18)
 815     DEFINE_CLASS_ID(OpaqueTemplateAssertionPredicate,  Node, 19)
 816     DEFINE_CLASS_ID(Move,     Node, 20)
 817     DEFINE_CLASS_ID(LShift,   Node, 21)
 818     DEFINE_CLASS_ID(Neg,      Node, 22)
 819 
 820     _max_classes  = ClassMask_Neg
 821   };
 822   #undef DEFINE_CLASS_ID
 823 
 824   // Flags are sorted by usage frequency.
 825   enum NodeFlags {
 826     Flag_is_Copy                     = 1 << 0, // should be first bit to avoid shift
 827     Flag_rematerialize               = 1 << 1,
 828     Flag_needs_anti_dependence_check = 1 << 2,
 829     Flag_is_macro                    = 1 << 3,
 830     Flag_is_Con                      = 1 << 4,
 831     Flag_is_cisc_alternate           = 1 << 5,
 832     Flag_is_dead_loop_safe           = 1 << 6,
 833     Flag_may_be_short_branch         = 1 << 7,
 834     Flag_avoid_back_to_back_before   = 1 << 8,
 835     Flag_avoid_back_to_back_after    = 1 << 9,
 836     Flag_has_call                    = 1 << 10,
 837     Flag_has_swapped_edges           = 1 << 11,
 838     Flag_is_scheduled                = 1 << 12,
 839     Flag_is_expensive                = 1 << 13,
 840     Flag_is_predicated_vector        = 1 << 14,
 841     Flag_for_post_loop_opts_igvn     = 1 << 15,
 842     Flag_is_removed_by_peephole      = 1 << 16,
 843     Flag_is_predicated_using_blend   = 1 << 17,
 844     _last_flag                       = Flag_is_predicated_using_blend
 845   };
 846 
 847   class PD;
 848 
 849 private:
 850   juint _class_id;
 851   juint _flags;
 852 
 853 #ifdef ASSERT
 854   static juint max_flags();
 855 #endif
 856 
 857 protected:
 858   // These methods should be called from constructors only.
 859   void init_class_id(juint c) {
 860     _class_id = c; // cast out const
 861   }
 862   void init_flags(uint fl) {
 863     assert(fl <= max_flags(), "invalid node flag");
 864     _flags |= fl;
 865   }
 866   void clear_flag(uint fl) {
 867     assert(fl <= max_flags(), "invalid node flag");
 868     _flags &= ~fl;
 869   }
 870 
 871 public:
 872   juint class_id() const { return _class_id; }
 873 
 874   juint flags() const { return _flags; }
 875 
 876   void add_flag(juint fl) { init_flags(fl); }
 877 
 878   void remove_flag(juint fl) { clear_flag(fl); }
 879 
 880   // Return a dense integer opcode number
 881   virtual int Opcode() const;
 882 
 883   // Virtual inherited Node size
 884   virtual uint size_of() const;
 885 
 886   // Other interesting Node properties
 887   #define DEFINE_CLASS_QUERY(type)                           \
 888   bool is_##type() const {                                   \
 889     return ((_class_id & ClassMask_##type) == Class_##type); \
 890   }                                                          \
 891   type##Node *as_##type() const {                            \
 892     assert(is_##type(), "invalid node class: %s", Name());   \
 893     return (type##Node*)this;                                \
 894   }                                                          \
 895   type##Node* isa_##type() const {                           \
 896     return (is_##type()) ? as_##type() : nullptr;            \
 897   }
 898 
 899   DEFINE_CLASS_QUERY(AbstractLock)
 900   DEFINE_CLASS_QUERY(Add)
 901   DEFINE_CLASS_QUERY(AddP)
 902   DEFINE_CLASS_QUERY(Allocate)
 903   DEFINE_CLASS_QUERY(AllocateArray)
 904   DEFINE_CLASS_QUERY(ArrayCopy)
 905   DEFINE_CLASS_QUERY(BaseCountedLoop)
 906   DEFINE_CLASS_QUERY(BaseCountedLoopEnd)
 907   DEFINE_CLASS_QUERY(Blackhole)
 908   DEFINE_CLASS_QUERY(Bool)
 909   DEFINE_CLASS_QUERY(BoxLock)
 910   DEFINE_CLASS_QUERY(Call)
 911   DEFINE_CLASS_QUERY(CallDynamicJava)
 912   DEFINE_CLASS_QUERY(CallJava)
 913   DEFINE_CLASS_QUERY(CallLeaf)
 914   DEFINE_CLASS_QUERY(CallLeafNoFP)
 915   DEFINE_CLASS_QUERY(CallRuntime)
 916   DEFINE_CLASS_QUERY(CallStaticJava)
 917   DEFINE_CLASS_QUERY(Catch)
 918   DEFINE_CLASS_QUERY(CatchProj)
 919   DEFINE_CLASS_QUERY(CheckCastPP)
 920   DEFINE_CLASS_QUERY(CastII)
 921   DEFINE_CLASS_QUERY(CastLL)
 922   DEFINE_CLASS_QUERY(CastFF)
 923   DEFINE_CLASS_QUERY(ConI)
 924   DEFINE_CLASS_QUERY(CastPP)
 925   DEFINE_CLASS_QUERY(ConstraintCast)
 926   DEFINE_CLASS_QUERY(ClearArray)
 927   DEFINE_CLASS_QUERY(CMove)
 928   DEFINE_CLASS_QUERY(Cmp)
 929   DEFINE_CLASS_QUERY(Convert)
 930   DEFINE_CLASS_QUERY(CountedLoop)
 931   DEFINE_CLASS_QUERY(CountedLoopEnd)
 932   DEFINE_CLASS_QUERY(DecodeNarrowPtr)
 933   DEFINE_CLASS_QUERY(DecodeN)
 934   DEFINE_CLASS_QUERY(DecodeNKlass)
 935   DEFINE_CLASS_QUERY(EncodeNarrowPtr)
 936   DEFINE_CLASS_QUERY(EncodeP)
 937   DEFINE_CLASS_QUERY(EncodePKlass)
 938   DEFINE_CLASS_QUERY(FastLock)
 939   DEFINE_CLASS_QUERY(FastUnlock)
 940   DEFINE_CLASS_QUERY(FlatArrayCheck)
 941   DEFINE_CLASS_QUERY(Halt)
 942   DEFINE_CLASS_QUERY(If)
 943   DEFINE_CLASS_QUERY(RangeCheck)
 944   DEFINE_CLASS_QUERY(IfProj)
 945   DEFINE_CLASS_QUERY(IfFalse)
 946   DEFINE_CLASS_QUERY(IfTrue)
 947   DEFINE_CLASS_QUERY(Initialize)
 948   DEFINE_CLASS_QUERY(Jump)
 949   DEFINE_CLASS_QUERY(JumpProj)
 950   DEFINE_CLASS_QUERY(LongCountedLoop)
 951   DEFINE_CLASS_QUERY(LongCountedLoopEnd)
 952   DEFINE_CLASS_QUERY(Load)
 953   DEFINE_CLASS_QUERY(LoadStore)
 954   DEFINE_CLASS_QUERY(LoadStoreConditional)
 955   DEFINE_CLASS_QUERY(Lock)
 956   DEFINE_CLASS_QUERY(Loop)
 957   DEFINE_CLASS_QUERY(LShift)
 958   DEFINE_CLASS_QUERY(Mach)
 959   DEFINE_CLASS_QUERY(MachBranch)
 960   DEFINE_CLASS_QUERY(MachCall)
 961   DEFINE_CLASS_QUERY(MachCallDynamicJava)
 962   DEFINE_CLASS_QUERY(MachCallJava)
 963   DEFINE_CLASS_QUERY(MachCallLeaf)
 964   DEFINE_CLASS_QUERY(MachCallRuntime)
 965   DEFINE_CLASS_QUERY(MachCallStaticJava)
 966   DEFINE_CLASS_QUERY(MachConstantBase)
 967   DEFINE_CLASS_QUERY(MachConstant)
 968   DEFINE_CLASS_QUERY(MachGoto)
 969   DEFINE_CLASS_QUERY(MachIf)
 970   DEFINE_CLASS_QUERY(MachJump)
 971   DEFINE_CLASS_QUERY(MachNullCheck)
 972   DEFINE_CLASS_QUERY(MachProj)
 973   DEFINE_CLASS_QUERY(MachProlog)
 974   DEFINE_CLASS_QUERY(MachReturn)
 975   DEFINE_CLASS_QUERY(MachSafePoint)
 976   DEFINE_CLASS_QUERY(MachSpillCopy)
 977   DEFINE_CLASS_QUERY(MachTemp)
 978   DEFINE_CLASS_QUERY(MachMemBar)
 979   DEFINE_CLASS_QUERY(MachMerge)
 980   DEFINE_CLASS_QUERY(MachVEP)
 981   DEFINE_CLASS_QUERY(Mem)
 982   DEFINE_CLASS_QUERY(MemBar)
 983   DEFINE_CLASS_QUERY(MemBarStoreStore)
 984   DEFINE_CLASS_QUERY(MergeMem)
 985   DEFINE_CLASS_QUERY(Move)
 986   DEFINE_CLASS_QUERY(Mul)
 987   DEFINE_CLASS_QUERY(Multi)
 988   DEFINE_CLASS_QUERY(MultiBranch)
 989   DEFINE_CLASS_QUERY(MulVL)
 990   DEFINE_CLASS_QUERY(Neg)
 991   DEFINE_CLASS_QUERY(NegV)
 992   DEFINE_CLASS_QUERY(NeverBranch)
 993   DEFINE_CLASS_QUERY(Opaque1)
 994   DEFINE_CLASS_QUERY(OpaqueNotNull)
 995   DEFINE_CLASS_QUERY(OpaqueInitializedAssertionPredicate)
 996   DEFINE_CLASS_QUERY(OpaqueTemplateAssertionPredicate)
 997   DEFINE_CLASS_QUERY(OpaqueLoopInit)
 998   DEFINE_CLASS_QUERY(OpaqueLoopStride)
 999   DEFINE_CLASS_QUERY(OpaqueMultiversioning)
1000   DEFINE_CLASS_QUERY(OuterStripMinedLoop)
1001   DEFINE_CLASS_QUERY(OuterStripMinedLoopEnd)
1002   DEFINE_CLASS_QUERY(Parm)
1003   DEFINE_CLASS_QUERY(ParsePredicate)
1004   DEFINE_CLASS_QUERY(PCTable)
1005   DEFINE_CLASS_QUERY(Phi)
1006   DEFINE_CLASS_QUERY(Proj)
1007   DEFINE_CLASS_QUERY(Reduction)
1008   DEFINE_CLASS_QUERY(Region)
1009   DEFINE_CLASS_QUERY(Root)
1010   DEFINE_CLASS_QUERY(SafePoint)
1011   DEFINE_CLASS_QUERY(SafePointScalarObject)
1012   DEFINE_CLASS_QUERY(SafePointScalarMerge)
1013   DEFINE_CLASS_QUERY(Start)
1014   DEFINE_CLASS_QUERY(Store)
1015   DEFINE_CLASS_QUERY(Sub)
1016   DEFINE_CLASS_QUERY(SubTypeCheck)
1017   DEFINE_CLASS_QUERY(Type)
1018   DEFINE_CLASS_QUERY(InlineType)
1019   DEFINE_CLASS_QUERY(Vector)
1020   DEFINE_CLASS_QUERY(VectorMaskCmp)
1021   DEFINE_CLASS_QUERY(VectorUnbox)
1022   DEFINE_CLASS_QUERY(VectorReinterpret)
1023   DEFINE_CLASS_QUERY(CompressV)
1024   DEFINE_CLASS_QUERY(ExpandV)
1025   DEFINE_CLASS_QUERY(CompressM)
1026   DEFINE_CLASS_QUERY(LoadVector)
1027   DEFINE_CLASS_QUERY(LoadVectorGather)
1028   DEFINE_CLASS_QUERY(LoadVectorMasked)
1029   DEFINE_CLASS_QUERY(LoadVectorGatherMasked)
1030   DEFINE_CLASS_QUERY(StoreVector)
1031   DEFINE_CLASS_QUERY(StoreVectorScatter)
1032   DEFINE_CLASS_QUERY(StoreVectorMasked)
1033   DEFINE_CLASS_QUERY(StoreVectorScatterMasked)
1034   DEFINE_CLASS_QUERY(SaturatingVector)
1035   DEFINE_CLASS_QUERY(ShiftV)
1036   DEFINE_CLASS_QUERY(Unlock)
1037 
1038   #undef DEFINE_CLASS_QUERY
1039 
1040   // duplicate of is_MachSpillCopy()
1041   bool is_SpillCopy () const {
1042     return ((_class_id & ClassMask_MachSpillCopy) == Class_MachSpillCopy);
1043   }
1044 
1045   bool is_Con () const { return (_flags & Flag_is_Con) != 0; }
1046   // The data node which is safe to leave in dead loop during IGVN optimization.
1047   bool is_dead_loop_safe() const;
1048 
1049   // is_Copy() returns copied edge index (0 or 1)
1050   uint is_Copy() const { return (_flags & Flag_is_Copy); }
1051 
1052   virtual bool is_CFG() const { return false; }
1053 
1054   // If this node is control-dependent on a test, can it be
1055   // rerouted to a dominating equivalent test?  This is usually
1056   // true of non-CFG nodes, but can be false for operations which
1057   // depend for their correct sequencing on more than one test.
1058   // (In that case, hoisting to a dominating test may silently
1059   // skip some other important test.)
1060   virtual bool depends_only_on_test() const { assert(!is_CFG(), ""); return true; };
1061 
1062   // When building basic blocks, I need to have a notion of block beginning
1063   // Nodes, next block selector Nodes (block enders), and next block
1064   // projections.  These calls need to work on their machine equivalents.  The
1065   // Ideal beginning Nodes are RootNode, RegionNode and StartNode.
1066   bool is_block_start() const {
1067     if ( is_Region() )
1068       return this == (const Node*)in(0);
1069     else
1070       return is_Start();
1071   }
1072 
1073   // The Ideal control projection Nodes are IfTrue/IfFalse, JumpProjNode, Root,
1074   // Goto and Return.  This call also returns the block ending Node.
1075   virtual const Node *is_block_proj() const;
1076 
1077   // The node is a "macro" node which needs to be expanded before matching
1078   bool is_macro() const { return (_flags & Flag_is_macro) != 0; }
1079   // The node is expensive: the best control is set during loop opts
1080   bool is_expensive() const { return (_flags & Flag_is_expensive) != 0 && in(0) != nullptr; }
1081   // The node's original edge position is swapped.
1082   bool has_swapped_edges() const { return (_flags & Flag_has_swapped_edges) != 0; }
1083 
1084   bool is_predicated_vector() const { return (_flags & Flag_is_predicated_vector) != 0; }
1085 
1086   bool is_predicated_using_blend() const { return (_flags & Flag_is_predicated_using_blend) != 0; }
1087 
1088   // Used in lcm to mark nodes that have scheduled
1089   bool is_scheduled() const { return (_flags & Flag_is_scheduled) != 0; }
1090 
1091   bool for_post_loop_opts_igvn() const { return (_flags & Flag_for_post_loop_opts_igvn) != 0; }
1092 
1093   // Is 'n' possibly a loop entry (i.e. a Parse Predicate projection)?
1094   static bool may_be_loop_entry(Node* n) {
1095     return n != nullptr && n->is_IfProj() && n->in(0)->is_ParsePredicate();
1096   }
1097 
1098 //----------------- Optimization
1099 
1100   // Get the worst-case Type output for this Node.
1101   virtual const class Type *bottom_type() const;
1102 
1103   // If we find a better type for a node, try to record it permanently.
1104   // Return true if this node actually changed.
1105   // Be sure to do the hash_delete game in the "rehash" variant.
1106   void raise_bottom_type(const Type* new_type);
1107 
1108   // Get the address type with which this node uses and/or defs memory,
1109   // or null if none.  The address type is conservatively wide.
1110   // Returns non-null for calls, membars, loads, stores, etc.
1111   // Returns TypePtr::BOTTOM if the node touches memory "broadly".
1112   virtual const class TypePtr *adr_type() const { return nullptr; }
1113 
1114   // Return an existing node which computes the same function as this node.
1115   // The optimistic combined algorithm requires this to return a Node which
1116   // is a small number of steps away (e.g., one of my inputs).
1117   virtual Node* Identity(PhaseGVN* phase);
1118 
1119   // Return the set of values this Node can take on at runtime.
1120   virtual const Type* Value(PhaseGVN* phase) const;
1121 
1122   // Return a node which is more "ideal" than the current node.
1123   // The invariants on this call are subtle.  If in doubt, read the
1124   // treatise in node.cpp above the default implementation AND TEST WITH
1125   // -XX:VerifyIterativeGVN=1
1126   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
1127 
1128   // Some nodes have specific Ideal subgraph transformations only if they are
1129   // unique users of specific nodes. Such nodes should be put on IGVN worklist
1130   // for the transformations to happen.
1131   bool has_special_unique_user() const;
1132 
1133   // Skip Proj and CatchProj nodes chains. Check for Null and Top.
1134   Node* find_exact_control(Node* ctrl);
1135 
1136   // Results of the dominance analysis.
1137   enum class DomResult {
1138     NotDominate,         // 'this' node does not dominate 'sub'.
1139     Dominate,            // 'this' node dominates or is equal to 'sub'.
1140     EncounteredDeadCode  // Result is undefined due to encountering dead code.
1141   };
1142   // Check if 'this' node dominates or equal to 'sub'.
1143   DomResult dominates(Node* sub, Node_List &nlist);
1144 
1145   bool remove_dead_region(PhaseGVN *phase, bool can_reshape);
1146 public:
1147 
1148   // See if there is valid pipeline info
1149   static  const Pipeline *pipeline_class();
1150   virtual const Pipeline *pipeline() const;
1151 
1152   // Compute the latency from the def to this instruction of the ith input node
1153   uint latency(uint i);
1154 
1155   // Hash & compare functions, for pessimistic value numbering
1156 
1157   // If the hash function returns the special sentinel value NO_HASH,
1158   // the node is guaranteed never to compare equal to any other node.
1159   // If we accidentally generate a hash with value NO_HASH the node
1160   // won't go into the table and we'll lose a little optimization.
1161   static const uint NO_HASH = 0;
1162   virtual uint hash() const;
1163   virtual bool cmp( const Node &n ) const;
1164 
1165   // Operation appears to be iteratively computed (such as an induction variable)
1166   // It is possible for this operation to return false for a loop-varying
1167   // value, if it appears (by local graph inspection) to be computed by a simple conditional.
1168   bool is_iteratively_computed();
1169 
1170   // Determine if a node is a counted loop induction variable.
1171   // NOTE: The method is defined in "loopnode.cpp".
1172   bool is_cloop_ind_var() const;
1173 
1174   // Return a node with opcode "opc" and same inputs as "this" if one can
1175   // be found; Otherwise return null;
1176   Node* find_similar(int opc);
1177 
1178   // Return the unique control out if only one. Null if none or more than one.
1179   Node* unique_ctrl_out_or_null() const;
1180   // Return the unique control out. Asserts if none or more than one control out.
1181   Node* unique_ctrl_out() const;
1182 
1183   // Set control or add control as precedence edge
1184   void ensure_control_or_add_prec(Node* c);
1185   void add_prec_from(Node* n);
1186 
1187   // Visit boundary uses of the node and apply a callback function for each.
1188   // Recursively traverse uses, stopping and applying the callback when
1189   // reaching a boundary node, defined by is_boundary. Note: the function
1190   // definition appears after the complete type definition of Node_List.
1191   template <typename Callback, typename Check>
1192   void visit_uses(Callback callback, Check is_boundary) const;
1193 
1194   // Returns a clone of the current node that's pinned (if the current node is not) for nodes found in array accesses
1195   // (Load and range check CastII nodes).
1196   // This is used when an array access is made dependent on 2 or more range checks (range check smearing or Loop Predication).
1197   virtual Node* pin_array_access_node() const {
1198     return nullptr;
1199   }
1200 
1201   //----------------- Code Generation
1202 
1203   // Ideal register class for Matching.  Zero means unmatched instruction
1204   // (these are cloned instead of converted to machine nodes).
1205   virtual uint ideal_reg() const;
1206 
1207   static const uint NotAMachineReg;   // must be > max. machine register
1208 
1209   // Do we Match on this edge index or not?  Generally false for Control
1210   // and true for everything else.  Weird for calls & returns.
1211   virtual uint match_edge(uint idx) const;
1212 
1213   // Register class output is returned in
1214   virtual const RegMask &out_RegMask() const;
1215   // Register class input is expected in
1216   virtual const RegMask &in_RegMask(uint) const;
1217   // Should we clone rather than spill this instruction?
1218   bool rematerialize() const;
1219 
1220   // Return JVM State Object if this Node carries debug info, or null otherwise
1221   virtual JVMState* jvms() const;
1222 
1223   // Print as assembly
1224   virtual void format( PhaseRegAlloc *, outputStream* st = tty ) const;
1225   // Emit bytes using C2_MacroAssembler
1226   virtual void emit(C2_MacroAssembler *masm, PhaseRegAlloc *ra_) const;
1227   // Size of instruction in bytes
1228   virtual uint size(PhaseRegAlloc *ra_) const;
1229 
1230   // Convenience function to extract an integer constant from a node.
1231   // If it is not an integer constant (either Con, CastII, or Mach),
1232   // return value_if_unknown.
1233   jint find_int_con(jint value_if_unknown) const {
1234     const TypeInt* t = find_int_type();
1235     return (t != nullptr && t->is_con()) ? t->get_con() : value_if_unknown;
1236   }
1237   // Return the constant, knowing it is an integer constant already
1238   jint get_int() const {
1239     const TypeInt* t = find_int_type();
1240     guarantee(t != nullptr, "must be con");
1241     return t->get_con();
1242   }
1243   // Here's where the work is done.  Can produce non-constant int types too.
1244   const TypeInt* find_int_type() const;
1245   const TypeInteger* find_integer_type(BasicType bt) const;
1246 
1247   // Same thing for long (and intptr_t, via type.hpp):
1248   jlong get_long() const {
1249     const TypeLong* t = find_long_type();
1250     guarantee(t != nullptr, "must be con");
1251     return t->get_con();
1252   }
1253   jlong find_long_con(jint value_if_unknown) const {
1254     const TypeLong* t = find_long_type();
1255     return (t != nullptr && t->is_con()) ? t->get_con() : value_if_unknown;
1256   }
1257   const TypeLong* find_long_type() const;
1258 
1259   jlong get_integer_as_long(BasicType bt) const {
1260     const TypeInteger* t = find_integer_type(bt);
1261     guarantee(t != nullptr && t->is_con(), "must be con");
1262     return t->get_con_as_long(bt);
1263   }
1264   jlong find_integer_as_long(BasicType bt, jlong value_if_unknown) const {
1265     const TypeInteger* t = find_integer_type(bt);
1266     if (t == nullptr || !t->is_con())  return value_if_unknown;
1267     return t->get_con_as_long(bt);
1268   }
1269   const TypePtr* get_ptr_type() const;
1270 
1271   // These guys are called by code generated by ADLC:
1272   intptr_t get_ptr() const;
1273   intptr_t get_narrowcon() const;
1274   jdouble getd() const;
1275   jfloat getf() const;
1276   jshort geth() const;
1277 
1278   // Nodes which are pinned into basic blocks
1279   virtual bool pinned() const { return false; }
1280 
1281   // Nodes which use memory without consuming it, hence need antidependences
1282   // More specifically, needs_anti_dependence_check returns true iff the node
1283   // (a) does a load, and (b) does not perform a store (except perhaps to a
1284   // stack slot or some other unaliased location).
1285   bool needs_anti_dependence_check() const;
1286 
1287   // Return which operand this instruction may cisc-spill. In other words,
1288   // return operand position that can convert from reg to memory access
1289   virtual int cisc_operand() const { return AdlcVMDeps::Not_cisc_spillable; }
1290   bool is_cisc_alternate() const { return (_flags & Flag_is_cisc_alternate) != 0; }
1291 
1292   // Whether this is a memory-writing machine node.
1293   bool is_memory_writer() const { return is_Mach() && bottom_type()->has_memory(); }
1294 
1295   // Whether this is a memory phi node
1296   bool is_memory_phi() const { return is_Phi() && bottom_type() == Type::MEMORY; }
1297 
1298   bool is_div_or_mod(BasicType bt) const;
1299 
1300   bool is_pure_function() const;
1301 
1302   bool is_data_proj_of_pure_function(const Node* maybe_pure_function) const;
1303 
1304 //----------------- Printing, etc
1305 #ifndef PRODUCT
1306  public:
1307   Node* find(int idx, bool only_ctrl = false); // Search the graph for the given idx.
1308   Node* find_ctrl(int idx); // Search control ancestors for the given idx.
1309   void dump_bfs(const int max_distance, Node* target, const char* options, outputStream* st) const;
1310   void dump_bfs(const int max_distance, Node* target, const char* options) const; // directly to tty
1311   void dump_bfs(const int max_distance) const; // dump_bfs(max_distance, nullptr, nullptr)
1312   class DumpConfig {
1313    public:
1314     // overridden to implement coloring of node idx
1315     virtual void pre_dump(outputStream *st, const Node* n) = 0;
1316     virtual void post_dump(outputStream *st) = 0;
1317   };
1318   void dump_idx(bool align = false, outputStream* st = tty, DumpConfig* dc = nullptr) const;
1319   void dump_name(outputStream* st = tty, DumpConfig* dc = nullptr) const;
1320   void dump() const; // print node with newline
1321   void dump(const char* suffix, bool mark = false, outputStream* st = tty, DumpConfig* dc = nullptr) const; // Print this node.
1322   void dump(int depth) const;        // Print this node, recursively to depth d
1323   void dump_ctrl(int depth) const;   // Print control nodes, to depth d
1324   void dump_comp() const;            // Print this node in compact representation.
1325   // Print this node in compact representation.
1326   void dump_comp(const char* suffix, outputStream *st = tty) const;
1327  private:
1328   virtual void dump_req(outputStream* st = tty, DumpConfig* dc = nullptr) const;    // Print required-edge info
1329   virtual void dump_prec(outputStream* st = tty, DumpConfig* dc = nullptr) const;   // Print precedence-edge info
1330   virtual void dump_out(outputStream* st = tty, DumpConfig* dc = nullptr) const;    // Print the output edge info
1331  public:
1332   virtual void dump_spec(outputStream *st) const {};      // Print per-node info
1333   // Print compact per-node info
1334   virtual void dump_compact_spec(outputStream *st) const { dump_spec(st); }
1335 
1336   static void verify(int verify_depth, VectorSet& visited, Node_List& worklist);
1337 
1338   // This call defines a class-unique string used to identify class instances
1339   virtual const char *Name() const;
1340 
1341   void dump_format(PhaseRegAlloc *ra) const; // debug access to MachNode::format(...)
1342   static bool in_dump() { return Compile::current()->_in_dump_cnt > 0; } // check if we are in a dump call
1343 #endif
1344 #ifdef ASSERT
1345   void verify_construction();
1346   bool verify_jvms(const JVMState* jvms) const;
1347 
1348   Node* _debug_orig;                   // Original version of this, if any.
1349   Node*  debug_orig() const            { return _debug_orig; }
1350   void   set_debug_orig(Node* orig);   // _debug_orig = orig
1351   void   dump_orig(outputStream *st, bool print_key = true) const;
1352 
1353   uint64_t _debug_idx;                 // Unique value assigned to every node.
1354   uint64_t debug_idx() const           { return _debug_idx; }
1355   void set_debug_idx(uint64_t debug_idx) { _debug_idx = debug_idx; }
1356 
1357   int        _hash_lock;               // Barrier to modifications of nodes in the hash table
1358   void  enter_hash_lock() { ++_hash_lock; assert(_hash_lock < 99, "in too many hash tables?"); }
1359   void   exit_hash_lock() { --_hash_lock; assert(_hash_lock >= 0, "mispaired hash locks"); }
1360 
1361   static void init_NodeProperty();
1362 
1363   #if OPTO_DU_ITERATOR_ASSERT
1364   const Node* _last_del;               // The last deleted node.
1365   uint        _del_tick;               // Bumped when a deletion happens..
1366   #endif
1367 #endif
1368 };
1369 
1370 inline bool not_a_node(const Node* n) {
1371   if (n == nullptr)                return true;
1372   if (((intptr_t)n & 1) != 0)      return true;  // uninitialized, etc.
1373   if (*(address*)n == badAddress)  return true;  // kill by Node::destruct
1374   return false;
1375 }
1376 
1377 //-----------------------------------------------------------------------------
1378 // Iterators over DU info, and associated Node functions.
1379 
1380 #if OPTO_DU_ITERATOR_ASSERT
1381 
1382 // Common code for assertion checking on DU iterators.
1383 class DUIterator_Common {
1384 #ifdef ASSERT
1385  protected:
1386   bool         _vdui;               // cached value of VerifyDUIterators
1387   const Node*  _node;               // the node containing the _out array
1388   uint         _outcnt;             // cached node->_outcnt
1389   uint         _del_tick;           // cached node->_del_tick
1390   Node*        _last;               // last value produced by the iterator
1391 
1392   void sample(const Node* node);    // used by c'tor to set up for verifies
1393   void verify(const Node* node, bool at_end_ok = false);
1394   void verify_resync();
1395   void reset(const DUIterator_Common& that);
1396 
1397 // The VDUI_ONLY macro protects code conditionalized on VerifyDUIterators
1398   #define I_VDUI_ONLY(i,x) { if ((i)._vdui) { x; } }
1399 #else
1400   #define I_VDUI_ONLY(i,x) { }
1401 #endif //ASSERT
1402 };
1403 
1404 #define VDUI_ONLY(x)     I_VDUI_ONLY(*this, x)
1405 
1406 // Default DU iterator.  Allows appends onto the out array.
1407 // Allows deletion from the out array only at the current point.
1408 // Usage:
1409 //  for (DUIterator i = x->outs(); x->has_out(i); i++) {
1410 //    Node* y = x->out(i);
1411 //    ...
1412 //  }
1413 // Compiles in product mode to a unsigned integer index, which indexes
1414 // onto a repeatedly reloaded base pointer of x->_out.  The loop predicate
1415 // also reloads x->_outcnt.  If you delete, you must perform "--i" just
1416 // before continuing the loop.  You must delete only the last-produced
1417 // edge.  You must delete only a single copy of the last-produced edge,
1418 // or else you must delete all copies at once (the first time the edge
1419 // is produced by the iterator).
1420 class DUIterator : public DUIterator_Common {
1421   friend class Node;
1422 
1423   // This is the index which provides the product-mode behavior.
1424   // Whatever the product-mode version of the system does to the
1425   // DUI index is done to this index.  All other fields in
1426   // this class are used only for assertion checking.
1427   uint         _idx;
1428 
1429   #ifdef ASSERT
1430   uint         _refresh_tick;    // Records the refresh activity.
1431 
1432   void sample(const Node* node); // Initialize _refresh_tick etc.
1433   void verify(const Node* node, bool at_end_ok = false);
1434   void verify_increment();       // Verify an increment operation.
1435   void verify_resync();          // Verify that we can back up over a deletion.
1436   void verify_finish();          // Verify that the loop terminated properly.
1437   void refresh();                // Resample verification info.
1438   void reset(const DUIterator& that);  // Resample after assignment.
1439   #endif
1440 
1441   DUIterator(const Node* node, int dummy_to_avoid_conversion)
1442     { _idx = 0;                         debug_only(sample(node)); }
1443 
1444  public:
1445   // initialize to garbage; clear _vdui to disable asserts
1446   DUIterator()
1447     { /*initialize to garbage*/         debug_only(_vdui = false); }
1448 
1449   DUIterator(const DUIterator& that)
1450     { _idx = that._idx;                 debug_only(_vdui = false; reset(that)); }
1451 
1452   void operator++(int dummy_to_specify_postfix_op)
1453     { _idx++;                           VDUI_ONLY(verify_increment()); }
1454 
1455   void operator--()
1456     { VDUI_ONLY(verify_resync());       --_idx; }
1457 
1458   ~DUIterator()
1459     { VDUI_ONLY(verify_finish()); }
1460 
1461   void operator=(const DUIterator& that)
1462     { _idx = that._idx;                 debug_only(reset(that)); }
1463 };
1464 
1465 DUIterator Node::outs() const
1466   { return DUIterator(this, 0); }
1467 DUIterator& Node::refresh_out_pos(DUIterator& i) const
1468   { I_VDUI_ONLY(i, i.refresh());        return i; }
1469 bool Node::has_out(DUIterator& i) const
1470   { I_VDUI_ONLY(i, i.verify(this,true));return i._idx < _outcnt; }
1471 Node*    Node::out(DUIterator& i) const
1472   { I_VDUI_ONLY(i, i.verify(this));     return debug_only(i._last=) _out[i._idx]; }
1473 
1474 
1475 // Faster DU iterator.  Disallows insertions into the out array.
1476 // Allows deletion from the out array only at the current point.
1477 // Usage:
1478 //  for (DUIterator_Fast imax, i = x->fast_outs(imax); i < imax; i++) {
1479 //    Node* y = x->fast_out(i);
1480 //    ...
1481 //  }
1482 // Compiles in product mode to raw Node** pointer arithmetic, with
1483 // no reloading of pointers from the original node x.  If you delete,
1484 // you must perform "--i; --imax" just before continuing the loop.
1485 // If you delete multiple copies of the same edge, you must decrement
1486 // imax, but not i, multiple times:  "--i, imax -= num_edges".
1487 class DUIterator_Fast : public DUIterator_Common {
1488   friend class Node;
1489   friend class DUIterator_Last;
1490 
1491   // This is the pointer which provides the product-mode behavior.
1492   // Whatever the product-mode version of the system does to the
1493   // DUI pointer is done to this pointer.  All other fields in
1494   // this class are used only for assertion checking.
1495   Node**       _outp;
1496 
1497   #ifdef ASSERT
1498   void verify(const Node* node, bool at_end_ok = false);
1499   void verify_limit();
1500   void verify_resync();
1501   void verify_relimit(uint n);
1502   void reset(const DUIterator_Fast& that);
1503   #endif
1504 
1505   // Note:  offset must be signed, since -1 is sometimes passed
1506   DUIterator_Fast(const Node* node, ptrdiff_t offset)
1507     { _outp = node->_out + offset;      debug_only(sample(node)); }
1508 
1509  public:
1510   // initialize to garbage; clear _vdui to disable asserts
1511   DUIterator_Fast()
1512     { /*initialize to garbage*/         debug_only(_vdui = false); }
1513 
1514   DUIterator_Fast(const DUIterator_Fast& that)
1515     { _outp = that._outp;               debug_only(_vdui = false; reset(that)); }
1516 
1517   void operator++(int dummy_to_specify_postfix_op)
1518     { _outp++;                          VDUI_ONLY(verify(_node, true)); }
1519 
1520   void operator--()
1521     { VDUI_ONLY(verify_resync());       --_outp; }
1522 
1523   void operator-=(uint n)   // applied to the limit only
1524     { _outp -= n;           VDUI_ONLY(verify_relimit(n));  }
1525 
1526   bool operator<(DUIterator_Fast& limit) {
1527     I_VDUI_ONLY(*this, this->verify(_node, true));
1528     I_VDUI_ONLY(limit, limit.verify_limit());
1529     return _outp < limit._outp;
1530   }
1531 
1532   void operator=(const DUIterator_Fast& that)
1533     { _outp = that._outp;               debug_only(reset(that)); }
1534 };
1535 
1536 DUIterator_Fast Node::fast_outs(DUIterator_Fast& imax) const {
1537   // Assign a limit pointer to the reference argument:
1538   imax = DUIterator_Fast(this, (ptrdiff_t)_outcnt);
1539   // Return the base pointer:
1540   return DUIterator_Fast(this, 0);
1541 }
1542 Node* Node::fast_out(DUIterator_Fast& i) const {
1543   I_VDUI_ONLY(i, i.verify(this));
1544   return debug_only(i._last=) *i._outp;
1545 }
1546 
1547 
1548 // Faster DU iterator.  Requires each successive edge to be removed.
1549 // Does not allow insertion of any edges.
1550 // Usage:
1551 //  for (DUIterator_Last imin, i = x->last_outs(imin); i >= imin; i -= num_edges) {
1552 //    Node* y = x->last_out(i);
1553 //    ...
1554 //  }
1555 // Compiles in product mode to raw Node** pointer arithmetic, with
1556 // no reloading of pointers from the original node x.
1557 class DUIterator_Last : private DUIterator_Fast {
1558   friend class Node;
1559 
1560   #ifdef ASSERT
1561   void verify(const Node* node, bool at_end_ok = false);
1562   void verify_limit();
1563   void verify_step(uint num_edges);
1564   #endif
1565 
1566   // Note:  offset must be signed, since -1 is sometimes passed
1567   DUIterator_Last(const Node* node, ptrdiff_t offset)
1568     : DUIterator_Fast(node, offset) { }
1569 
1570   void operator++(int dummy_to_specify_postfix_op) {} // do not use
1571   void operator<(int)                              {} // do not use
1572 
1573  public:
1574   DUIterator_Last() { }
1575   // initialize to garbage
1576 
1577   DUIterator_Last(const DUIterator_Last& that) = default;
1578 
1579   void operator--()
1580     { _outp--;              VDUI_ONLY(verify_step(1));  }
1581 
1582   void operator-=(uint n)
1583     { _outp -= n;           VDUI_ONLY(verify_step(n));  }
1584 
1585   bool operator>=(DUIterator_Last& limit) {
1586     I_VDUI_ONLY(*this, this->verify(_node, true));
1587     I_VDUI_ONLY(limit, limit.verify_limit());
1588     return _outp >= limit._outp;
1589   }
1590 
1591   DUIterator_Last& operator=(const DUIterator_Last& that) = default;
1592 };
1593 
1594 DUIterator_Last Node::last_outs(DUIterator_Last& imin) const {
1595   // Assign a limit pointer to the reference argument:
1596   imin = DUIterator_Last(this, 0);
1597   // Return the initial pointer:
1598   return DUIterator_Last(this, (ptrdiff_t)_outcnt - 1);
1599 }
1600 Node* Node::last_out(DUIterator_Last& i) const {
1601   I_VDUI_ONLY(i, i.verify(this));
1602   return debug_only(i._last=) *i._outp;
1603 }
1604 
1605 #endif //OPTO_DU_ITERATOR_ASSERT
1606 
1607 #undef I_VDUI_ONLY
1608 #undef VDUI_ONLY
1609 
1610 // An Iterator that truly follows the iterator pattern.  Doesn't
1611 // support deletion but could be made to.
1612 //
1613 //   for (SimpleDUIterator i(n); i.has_next(); i.next()) {
1614 //     Node* m = i.get();
1615 //
1616 class SimpleDUIterator : public StackObj {
1617  private:
1618   Node* node;
1619   DUIterator_Fast imax;
1620   DUIterator_Fast i;
1621  public:
1622   SimpleDUIterator(Node* n): node(n), i(n->fast_outs(imax)) {}
1623   bool has_next() { return i < imax; }
1624   void next() { i++; }
1625   Node* get() { return node->fast_out(i); }
1626 };
1627 
1628 
1629 //-----------------------------------------------------------------------------
1630 // Map dense integer indices to Nodes.  Uses classic doubling-array trick.
1631 // Abstractly provides an infinite array of Node*'s, initialized to null.
1632 // Note that the constructor just zeros things, and since I use Arena
1633 // allocation I do not need a destructor to reclaim storage.
1634 class Node_Array : public AnyObj {
1635 protected:
1636   Arena* _a;                    // Arena to allocate in
1637   uint   _max;
1638   Node** _nodes;
1639   ReallocMark _nesting;         // Safety checks for arena reallocation
1640 
1641   // Grow array to required capacity
1642   void maybe_grow(uint i) {
1643     if (i >= _max) {
1644       grow(i);
1645     }
1646   }
1647   void grow(uint i);
1648 
1649 public:
1650   Node_Array(Arena* a, uint max = OptoNodeListSize) : _a(a), _max(max) {
1651     _nodes = NEW_ARENA_ARRAY(a, Node*, max);
1652     clear();
1653   }
1654   Node_Array() : Node_Array(Thread::current()->resource_area()) {}
1655 
1656   NONCOPYABLE(Node_Array);
1657   Node_Array& operator=(Node_Array&&) = delete;
1658   // Allow move constructor for && (eg. capture return of function)
1659   Node_Array(Node_Array&&) = default;
1660 
1661   Node *operator[] ( uint i ) const // Lookup, or null for not mapped
1662   { return (i<_max) ? _nodes[i] : (Node*)nullptr; }
1663   Node* at(uint i) const { assert(i<_max,"oob"); return _nodes[i]; }
1664   Node** adr() { return _nodes; }
1665   // Extend the mapping: index i maps to Node *n.
1666   void map( uint i, Node *n ) { maybe_grow(i); _nodes[i] = n; }
1667   void insert( uint i, Node *n );
1668   void remove( uint i );        // Remove, preserving order
1669   // Clear all entries in _nodes to null but keep storage
1670   void clear() {
1671     Copy::zero_to_bytes(_nodes, _max * sizeof(Node*));
1672   }
1673 
1674   uint max() const { return _max; }
1675   void dump() const;
1676 };
1677 
1678 class Node_List : public Node_Array {
1679   uint _cnt;
1680 public:
1681   Node_List(uint max = OptoNodeListSize) : Node_Array(Thread::current()->resource_area(), max), _cnt(0) {}
1682   Node_List(Arena *a, uint max = OptoNodeListSize) : Node_Array(a, max), _cnt(0) {}
1683 
1684   NONCOPYABLE(Node_List);
1685   Node_List& operator=(Node_List&&) = delete;
1686   // Allow move constructor for && (eg. capture return of function)
1687   Node_List(Node_List&&) = default;
1688 
1689   bool contains(const Node* n) const {
1690     for (uint e = 0; e < size(); e++) {
1691       if (at(e) == n) return true;
1692     }
1693     return false;
1694   }
1695   void insert( uint i, Node *n ) { Node_Array::insert(i,n); _cnt++; }
1696   void remove( uint i ) { Node_Array::remove(i); _cnt--; }
1697   void push( Node *b ) { map(_cnt++,b); }
1698   void yank( Node *n );         // Find and remove
1699   Node *pop() { return _nodes[--_cnt]; }
1700   void clear() { _cnt = 0; Node_Array::clear(); } // retain storage
1701   void copy(const Node_List& from) {
1702     if (from._max > _max) {
1703       grow(from._max);
1704     }
1705     _cnt = from._cnt;
1706     Copy::conjoint_words_to_higher((HeapWord*)&from._nodes[0], (HeapWord*)&_nodes[0], from._max * sizeof(Node*));
1707   }
1708 
1709   uint size() const { return _cnt; }
1710   void dump() const;
1711   void dump_simple() const;
1712 };
1713 
1714 // Definition must appear after complete type definition of Node_List
1715 template <typename Callback, typename Check>
1716 void Node::visit_uses(Callback callback, Check is_boundary) const {
1717   ResourceMark rm;
1718   VectorSet visited;
1719   Node_List worklist;
1720 
1721   // The initial worklist consists of the direct uses
1722   for (DUIterator_Fast kmax, k = fast_outs(kmax); k < kmax; k++) {
1723     Node* out = fast_out(k);
1724     if (!visited.test_set(out->_idx)) { worklist.push(out); }
1725   }
1726 
1727   while (worklist.size() > 0) {
1728     Node* use = worklist.pop();
1729     // Apply callback on boundary nodes
1730     if (is_boundary(use)) {
1731       callback(use);
1732     } else {
1733       // Not a boundary node, continue search
1734       for (DUIterator_Fast kmax, k = use->fast_outs(kmax); k < kmax; k++) {
1735         Node* out = use->fast_out(k);
1736         if (!visited.test_set(out->_idx)) { worklist.push(out); }
1737       }
1738     }
1739   }
1740 }
1741 
1742 
1743 //------------------------------Unique_Node_List-------------------------------
1744 class Unique_Node_List : public Node_List {
1745   VectorSet _in_worklist;
1746   uint _clock_index;            // Index in list where to pop from next
1747 public:
1748   Unique_Node_List() : Node_List(), _clock_index(0) {}
1749   Unique_Node_List(Arena *a) : Node_List(a), _in_worklist(a), _clock_index(0) {}
1750 
1751   NONCOPYABLE(Unique_Node_List);
1752   Unique_Node_List& operator=(Unique_Node_List&&) = delete;
1753   // Allow move constructor for && (eg. capture return of function)
1754   Unique_Node_List(Unique_Node_List&&) = default;
1755 
1756   void remove( Node *n );
1757   bool member( Node *n ) { return _in_worklist.test(n->_idx) != 0; }
1758   VectorSet& member_set(){ return _in_worklist; }
1759 
1760   void push(Node* b) {
1761     if( !_in_worklist.test_set(b->_idx) )
1762       Node_List::push(b);
1763   }
1764   void push_non_cfg_inputs_of(const Node* node) {
1765     for (uint i = 1; i < node->req(); i++) {
1766       Node* input = node->in(i);
1767       if (input != nullptr && !input->is_CFG()) {
1768         push(input);
1769       }
1770     }
1771   }
1772 
1773   void push_outputs_of(const Node* node) {
1774     for (DUIterator_Fast imax, i = node->fast_outs(imax); i < imax; i++) {
1775       Node* output = node->fast_out(i);
1776       push(output);
1777     }
1778   }
1779 
1780   Node *pop() {
1781     if( _clock_index >= size() ) _clock_index = 0;
1782     Node *b = at(_clock_index);
1783     map( _clock_index, Node_List::pop());
1784     if (size() != 0) _clock_index++; // Always start from 0
1785     _in_worklist.remove(b->_idx);
1786     return b;
1787   }
1788   Node *remove(uint i) {
1789     Node *b = Node_List::at(i);
1790     _in_worklist.remove(b->_idx);
1791     map(i,Node_List::pop());
1792     return b;
1793   }
1794   void yank(Node *n) {
1795     _in_worklist.remove(n->_idx);
1796     Node_List::yank(n);
1797   }
1798   void  clear() {
1799     _in_worklist.clear();        // Discards storage but grows automatically
1800     Node_List::clear();
1801     _clock_index = 0;
1802   }
1803   void ensure_empty() {
1804     assert(size() == 0, "must be empty");
1805     clear(); // just in case
1806   }
1807 
1808   // Used after parsing to remove useless nodes before Iterative GVN
1809   void remove_useless_nodes(VectorSet& useful);
1810 
1811   // If the idx of the Nodes change, we must recompute the VectorSet
1812   void recompute_idx_set() {
1813     _in_worklist.clear();
1814     for (uint i = 0; i < size(); i++) {
1815       Node* n = at(i);
1816       _in_worklist.set(n->_idx);
1817     }
1818   }
1819 
1820 #ifdef ASSERT
1821   bool is_subset_of(Unique_Node_List& other) {
1822     for (uint i = 0; i < size(); i++) {
1823       Node* n = at(i);
1824       if (!other.member(n)) {
1825         return false;
1826       }
1827     }
1828     return true;
1829   }
1830 #endif
1831 
1832   bool contains(const Node* n) const {
1833     fatal("use faster member() instead");
1834     return false;
1835   }
1836 
1837 #ifndef PRODUCT
1838   void print_set() const { _in_worklist.print(); }
1839 #endif
1840 };
1841 
1842 // Unique_Mixed_Node_List
1843 // unique: nodes are added only once
1844 // mixed: allow new and old nodes
1845 class Unique_Mixed_Node_List : public ResourceObj {
1846 public:
1847   Unique_Mixed_Node_List() : _visited_set(cmpkey, hashkey) {}
1848 
1849   void add(Node* node) {
1850     if (not_a_node(node)) {
1851       return; // Gracefully handle null, -1, 0xabababab, etc.
1852     }
1853     if (_visited_set[node] == nullptr) {
1854       _visited_set.Insert(node, node);
1855       _worklist.push(node);
1856     }
1857   }
1858 
1859   Node* operator[] (uint i) const {
1860     return _worklist[i];
1861   }
1862 
1863   size_t size() {
1864     return _worklist.size();
1865   }
1866 
1867 private:
1868   Dict _visited_set;
1869   Node_List _worklist;
1870 };
1871 
1872 // Inline definition of Compile::record_for_igvn must be deferred to this point.
1873 inline void Compile::record_for_igvn(Node* n) {
1874   _igvn_worklist->push(n);
1875 }
1876 
1877 // Inline definition of Compile::remove_for_igvn must be deferred to this point.
1878 inline void Compile::remove_for_igvn(Node* n) {
1879   _igvn_worklist->remove(n);
1880 }
1881 
1882 //------------------------------Node_Stack-------------------------------------
1883 class Node_Stack {
1884 protected:
1885   struct INode {
1886     Node *node; // Processed node
1887     uint  indx; // Index of next node's child
1888   };
1889   INode *_inode_top; // tos, stack grows up
1890   INode *_inode_max; // End of _inodes == _inodes + _max
1891   INode *_inodes;    // Array storage for the stack
1892   Arena *_a;         // Arena to allocate in
1893   ReallocMark _nesting; // Safety checks for arena reallocation
1894   void grow();
1895 public:
1896   Node_Stack(int size) {
1897     size_t max = (size > OptoNodeListSize) ? size : OptoNodeListSize;
1898     _a = Thread::current()->resource_area();
1899     _inodes = NEW_ARENA_ARRAY( _a, INode, max );
1900     _inode_max = _inodes + max;
1901     _inode_top = _inodes - 1; // stack is empty
1902   }
1903 
1904   Node_Stack(Arena *a, int size) : _a(a) {
1905     size_t max = (size > OptoNodeListSize) ? size : OptoNodeListSize;
1906     _inodes = NEW_ARENA_ARRAY( _a, INode, max );
1907     _inode_max = _inodes + max;
1908     _inode_top = _inodes - 1; // stack is empty
1909   }
1910 
1911   void pop() {
1912     assert(_inode_top >= _inodes, "node stack underflow");
1913     --_inode_top;
1914   }
1915   void push(Node *n, uint i) {
1916     ++_inode_top;
1917     grow();
1918     INode *top = _inode_top; // optimization
1919     top->node = n;
1920     top->indx = i;
1921   }
1922   Node *node() const {
1923     return _inode_top->node;
1924   }
1925   Node* node_at(uint i) const {
1926     assert(_inodes + i <= _inode_top, "in range");
1927     return _inodes[i].node;
1928   }
1929   uint index() const {
1930     return _inode_top->indx;
1931   }
1932   uint index_at(uint i) const {
1933     assert(_inodes + i <= _inode_top, "in range");
1934     return _inodes[i].indx;
1935   }
1936   void set_node(Node *n) {
1937     _inode_top->node = n;
1938   }
1939   void set_index(uint i) {
1940     _inode_top->indx = i;
1941   }
1942   uint size_max() const { return (uint)pointer_delta(_inode_max, _inodes,  sizeof(INode)); } // Max size
1943   uint size() const { return (uint)pointer_delta((_inode_top+1), _inodes,  sizeof(INode)); } // Current size
1944   bool is_nonempty() const { return (_inode_top >= _inodes); }
1945   bool is_empty() const { return (_inode_top < _inodes); }
1946   void clear() { _inode_top = _inodes - 1; } // retain storage
1947 
1948   // Node_Stack is used to map nodes.
1949   Node* find(uint idx) const;
1950 
1951   NONCOPYABLE(Node_Stack);
1952 };
1953 
1954 
1955 //-----------------------------Node_Notes--------------------------------------
1956 // Debugging or profiling annotations loosely and sparsely associated
1957 // with some nodes.  See Compile::node_notes_at for the accessor.
1958 class Node_Notes {
1959   JVMState* _jvms;
1960 
1961 public:
1962   Node_Notes(JVMState* jvms = nullptr) {
1963     _jvms = jvms;
1964   }
1965 
1966   JVMState* jvms()            { return _jvms; }
1967   void  set_jvms(JVMState* x) {        _jvms = x; }
1968 
1969   // True if there is nothing here.
1970   bool is_clear() {
1971     return (_jvms == nullptr);
1972   }
1973 
1974   // Make there be nothing here.
1975   void clear() {
1976     _jvms = nullptr;
1977   }
1978 
1979   // Make a new, clean node notes.
1980   static Node_Notes* make(Compile* C) {
1981     Node_Notes* nn = NEW_ARENA_ARRAY(C->comp_arena(), Node_Notes, 1);
1982     nn->clear();
1983     return nn;
1984   }
1985 
1986   Node_Notes* clone(Compile* C) {
1987     Node_Notes* nn = NEW_ARENA_ARRAY(C->comp_arena(), Node_Notes, 1);
1988     (*nn) = (*this);
1989     return nn;
1990   }
1991 
1992   // Absorb any information from source.
1993   bool update_from(Node_Notes* source) {
1994     bool changed = false;
1995     if (source != nullptr) {
1996       if (source->jvms() != nullptr) {
1997         set_jvms(source->jvms());
1998         changed = true;
1999       }
2000     }
2001     return changed;
2002   }
2003 };
2004 
2005 // Inlined accessors for Compile::node_nodes that require the preceding class:
2006 inline Node_Notes*
2007 Compile::locate_node_notes(GrowableArray<Node_Notes*>* arr,
2008                            int idx, bool can_grow) {
2009   assert(idx >= 0, "oob");
2010   int block_idx = (idx >> _log2_node_notes_block_size);
2011   int grow_by = (block_idx - (arr == nullptr? 0: arr->length()));
2012   if (grow_by >= 0) {
2013     if (!can_grow) return nullptr;
2014     grow_node_notes(arr, grow_by + 1);
2015   }
2016   if (arr == nullptr) return nullptr;
2017   // (Every element of arr is a sub-array of length _node_notes_block_size.)
2018   return arr->at(block_idx) + (idx & (_node_notes_block_size-1));
2019 }
2020 
2021 inline Node_Notes* Compile::node_notes_at(int idx) {
2022   return locate_node_notes(_node_note_array, idx, false);
2023 }
2024 
2025 inline bool
2026 Compile::set_node_notes_at(int idx, Node_Notes* value) {
2027   if (value == nullptr || value->is_clear())
2028     return false;  // nothing to write => write nothing
2029   Node_Notes* loc = locate_node_notes(_node_note_array, idx, true);
2030   assert(loc != nullptr, "");
2031   return loc->update_from(value);
2032 }
2033 
2034 
2035 //------------------------------TypeNode---------------------------------------
2036 // Node with a Type constant.
2037 class TypeNode : public Node {
2038 protected:
2039   virtual uint hash() const;    // Check the type
2040   virtual bool cmp( const Node &n ) const;
2041   virtual uint size_of() const; // Size is bigger
2042   const Type* const _type;
2043 public:
2044   void set_type(const Type* t) {
2045     assert(t != nullptr, "sanity");
2046     debug_only(uint check_hash = (VerifyHashTableKeys && _hash_lock) ? hash() : NO_HASH);
2047     *(const Type**)&_type = t;   // cast away const-ness
2048     // If this node is in the hash table, make sure it doesn't need a rehash.
2049     assert(check_hash == NO_HASH || check_hash == hash(), "type change must preserve hash code");
2050   }
2051   const Type* type() const { assert(_type != nullptr, "sanity"); return _type; };
2052   TypeNode( const Type *t, uint required ) : Node(required), _type(t) {
2053     init_class_id(Class_Type);
2054   }
2055   virtual const Type* Value(PhaseGVN* phase) const;
2056   virtual const Type *bottom_type() const;
2057   virtual       uint  ideal_reg() const;
2058 #ifndef PRODUCT
2059   virtual void dump_spec(outputStream *st) const;
2060   virtual void dump_compact_spec(outputStream *st) const;
2061 #endif
2062 };
2063 
2064 #include "opto/opcodes.hpp"
2065 
2066 #define Op_IL(op) \
2067   inline int Op_ ## op(BasicType bt) { \
2068   assert(bt == T_INT || bt == T_LONG, "only for int or longs"); \
2069   if (bt == T_INT) { \
2070     return Op_## op ## I; \
2071   } \
2072   return Op_## op ## L; \
2073 }
2074 
2075 Op_IL(Add)
2076 Op_IL(Sub)
2077 Op_IL(Mul)
2078 Op_IL(URShift)
2079 Op_IL(LShift)
2080 Op_IL(Xor)
2081 Op_IL(Cmp)
2082 Op_IL(Div)
2083 Op_IL(Mod)
2084 Op_IL(UDiv)
2085 Op_IL(UMod)
2086 
2087 inline int Op_ConIL(BasicType bt) {
2088   assert(bt == T_INT || bt == T_LONG, "only for int or longs");
2089   if (bt == T_INT) {
2090     return Op_ConI;
2091   }
2092   return Op_ConL;
2093 }
2094 
2095 inline int Op_Cmp_unsigned(BasicType bt) {
2096   assert(bt == T_INT || bt == T_LONG, "only for int or longs");
2097   if (bt == T_INT) {
2098     return Op_CmpU;
2099   }
2100   return Op_CmpUL;
2101 }
2102 
2103 inline int Op_Cast(BasicType bt) {
2104   assert(bt == T_INT || bt == T_LONG, "only for int or longs");
2105   if (bt == T_INT) {
2106     return Op_CastII;
2107   }
2108   return Op_CastLL;
2109 }
2110 
2111 inline int Op_DivIL(BasicType bt, bool is_unsigned) {
2112   assert(bt == T_INT || bt == T_LONG, "only for int or longs");
2113   if (bt == T_INT) {
2114     if (is_unsigned) {
2115       return Op_UDivI;
2116     } else {
2117       return Op_DivI;
2118     }
2119   }
2120   if (is_unsigned) {
2121     return Op_UDivL;
2122   } else {
2123     return Op_DivL;
2124   }
2125 }
2126 
2127 inline int Op_DivModIL(BasicType bt, bool is_unsigned) {
2128   assert(bt == T_INT || bt == T_LONG, "only for int or longs");
2129   if (bt == T_INT) {
2130     if (is_unsigned) {
2131       return Op_UDivModI;
2132     } else {
2133       return Op_DivModI;
2134     }
2135   }
2136   if (is_unsigned) {
2137     return Op_UDivModL;
2138   } else {
2139     return Op_DivModL;
2140   }
2141 }
2142 
2143 // Interface to define actions that should be taken when running DataNodeBFS. Each use can extend this class to specify
2144 // a customized BFS.
2145 class BFSActions : public StackObj {
2146  public:
2147   // Should a node's inputs further be visited in the BFS traversal? By default, we visit all data inputs. Override this
2148   // method to provide a custom filter.
2149   virtual bool should_visit(Node* node) const {
2150     // By default, visit all inputs.
2151     return true;
2152   };
2153 
2154   // Is the visited node a target node that we are looking for in the BFS traversal? We do not visit its inputs further
2155   // but the BFS will continue to visit all unvisited nodes in the queue.
2156   virtual bool is_target_node(Node* node) const = 0;
2157 
2158   // Defines an action that should be taken when we visit a target node in the BFS traversal.
2159   virtual void target_node_action(Node* target_node) = 0;
2160 };
2161 
2162 // Class to perform a BFS traversal on the data nodes from a given start node. The provided BFSActions guide which
2163 // data node's inputs should be further visited, which data nodes are target nodes and what to do with the target nodes.
2164 class DataNodeBFS : public StackObj {
2165   BFSActions& _bfs_actions;
2166 
2167  public:
2168   explicit DataNodeBFS(BFSActions& bfs_action) : _bfs_actions(bfs_action) {}
2169 
2170   // Run the BFS starting from 'start_node' and apply the actions provided to this class.
2171   void run(Node* start_node) {
2172     ResourceMark rm;
2173     Unique_Node_List _nodes_to_visit;
2174     _nodes_to_visit.push(start_node);
2175     for (uint i = 0; i < _nodes_to_visit.size(); i++) {
2176       Node* next = _nodes_to_visit[i];
2177       for (uint j = 1; j < next->req(); j++) {
2178         Node* input = next->in(j);
2179         if (_bfs_actions.is_target_node(input)) {
2180           assert(_bfs_actions.should_visit(input), "must also pass node filter");
2181           _bfs_actions.target_node_action(input);
2182         } else if (_bfs_actions.should_visit(input)) {
2183           _nodes_to_visit.push(input);
2184         }
2185       }
2186     }
2187   }
2188 };
2189 
2190 #endif // SHARE_OPTO_NODE_HPP