1 /*
   2  * Copyright (c) 1998, 2023, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
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  24 
  25 #ifndef SHARE_OPTO_LOOPNODE_HPP
  26 #define SHARE_OPTO_LOOPNODE_HPP
  27 
  28 #include "opto/cfgnode.hpp"
  29 #include "opto/multnode.hpp"
  30 #include "opto/phaseX.hpp"
  31 #include "opto/subnode.hpp"
  32 #include "opto/type.hpp"
  33 
  34 class CmpNode;
  35 class BaseCountedLoopEndNode;
  36 class CountedLoopNode;
  37 class IdealLoopTree;
  38 class LoopNode;
  39 class Node;
  40 class OuterStripMinedLoopEndNode;
  41 class ParsePredicates;
  42 class PathFrequency;
  43 class PhaseIdealLoop;
  44 class CountedLoopReserveKit;
  45 class VectorSet;
  46 class Invariance;
  47 struct small_cache;
  48 
  49 //
  50 //                  I D E A L I Z E D   L O O P S
  51 //
  52 // Idealized loops are the set of loops I perform more interesting
  53 // transformations on, beyond simple hoisting.
  54 
  55 //------------------------------LoopNode---------------------------------------
  56 // Simple loop header.  Fall in path on left, loop-back path on right.
  57 class LoopNode : public RegionNode {
  58   // Size is bigger to hold the flags.  However, the flags do not change
  59   // the semantics so it does not appear in the hash & cmp functions.
  60   virtual uint size_of() const { return sizeof(*this); }
  61 protected:
  62   uint _loop_flags;
  63   // Names for flag bitfields
  64   enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
  65          MainHasNoPreLoop      = 1<<2,
  66          HasExactTripCount     = 1<<3,
  67          InnerLoop             = 1<<4,
  68          PartialPeelLoop       = 1<<5,
  69          PartialPeelFailed     = 1<<6,
  70          WasSlpAnalyzed        = 1<<7,
  71          PassedSlpAnalysis     = 1<<8,
  72          DoUnrollOnly          = 1<<9,
  73          VectorizedLoop        = 1<<10,
  74          HasAtomicPostLoop     = 1<<11,
  75          StripMined            = 1<<12,
  76          SubwordLoop           = 1<<13,
  77          ProfileTripFailed     = 1<<14,
  78          LoopNestInnerLoop     = 1<<15,
  79          LoopNestLongOuterLoop = 1<<16 };
  80   char _unswitch_count;
  81   enum { _unswitch_max=3 };
  82 
  83   // Expected trip count from profile data
  84   float _profile_trip_cnt;
  85 
  86 public:
  87   // Names for edge indices
  88   enum { Self=0, EntryControl, LoopBackControl };
  89 
  90   bool is_inner_loop() const { return _loop_flags & InnerLoop; }
  91   void set_inner_loop() { _loop_flags |= InnerLoop; }
  92 
  93   bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
  94   bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
  95   void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
  96   bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
  97   bool is_strip_mined() const { return _loop_flags & StripMined; }
  98   bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
  99   bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
 100   bool is_loop_nest_inner_loop() const { return _loop_flags & LoopNestInnerLoop; }
 101   bool is_loop_nest_outer_loop() const { return _loop_flags & LoopNestLongOuterLoop; }
 102 
 103   void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
 104   void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
 105   void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
 106   void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
 107   void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
 108   void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
 109   void mark_strip_mined() { _loop_flags |= StripMined; }
 110   void clear_strip_mined() { _loop_flags &= ~StripMined; }
 111   void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
 112   void mark_subword_loop() { _loop_flags |= SubwordLoop; }
 113   void mark_loop_nest_inner_loop() { _loop_flags |= LoopNestInnerLoop; }
 114   void mark_loop_nest_outer_loop() { _loop_flags |= LoopNestLongOuterLoop; }
 115 
 116   int unswitch_max() { return _unswitch_max; }
 117   int unswitch_count() { return _unswitch_count; }
 118 
 119   void set_unswitch_count(int val) {
 120     assert (val <= unswitch_max(), "too many unswitches");
 121     _unswitch_count = val;
 122   }
 123 
 124   void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
 125   float profile_trip_cnt()             { return _profile_trip_cnt; }
 126 
 127   LoopNode(Node *entry, Node *backedge)
 128     : RegionNode(3), _loop_flags(0), _unswitch_count(0),
 129       _profile_trip_cnt(COUNT_UNKNOWN) {
 130     init_class_id(Class_Loop);
 131     init_req(EntryControl, entry);
 132     init_req(LoopBackControl, backedge);
 133   }
 134 
 135   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 136   virtual int Opcode() const;
 137   bool can_be_counted_loop(PhaseValues* phase) const {
 138     return req() == 3 && in(0) != nullptr &&
 139       in(1) != nullptr && phase->type(in(1)) != Type::TOP &&
 140       in(2) != nullptr && phase->type(in(2)) != Type::TOP;
 141   }
 142   bool is_valid_counted_loop(BasicType bt) const;
 143 #ifndef PRODUCT
 144   virtual void dump_spec(outputStream *st) const;
 145 #endif
 146 
 147   void verify_strip_mined(int expect_skeleton) const NOT_DEBUG_RETURN;
 148   virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; }
 149   virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return nullptr; }
 150   virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return nullptr; }
 151   virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return nullptr; }
 152   virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return nullptr; }
 153 };
 154 
 155 //------------------------------Counted Loops----------------------------------
 156 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
 157 // path (and maybe some other exit paths).  The trip-counter exit is always
 158 // last in the loop.  The trip-counter have to stride by a constant;
 159 // the exit value is also loop invariant.
 160 
 161 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs.  The
 162 // CountedLoopNode has the incoming loop control and the loop-back-control
 163 // which is always the IfTrue before the matching CountedLoopEndNode.  The
 164 // CountedLoopEndNode has an incoming control (possibly not the
 165 // CountedLoopNode if there is control flow in the loop), the post-increment
 166 // trip-counter value, and the limit.  The trip-counter value is always of
 167 // the form (Op old-trip-counter stride).  The old-trip-counter is produced
 168 // by a Phi connected to the CountedLoopNode.  The stride is constant.
 169 // The Op is any commutable opcode, including Add, Mul, Xor.  The
 170 // CountedLoopEndNode also takes in the loop-invariant limit value.
 171 
 172 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
 173 // loop-back control.  From CountedLoopEndNodes I can reach CountedLoopNodes
 174 // via the old-trip-counter from the Op node.
 175 
 176 //------------------------------CountedLoopNode--------------------------------
 177 // CountedLoopNodes head simple counted loops.  CountedLoopNodes have as
 178 // inputs the incoming loop-start control and the loop-back control, so they
 179 // act like RegionNodes.  They also take in the initial trip counter, the
 180 // loop-invariant stride and the loop-invariant limit value.  CountedLoopNodes
 181 // produce a loop-body control and the trip counter value.  Since
 182 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
 183 
 184 class BaseCountedLoopNode : public LoopNode {
 185 public:
 186   BaseCountedLoopNode(Node *entry, Node *backedge)
 187     : LoopNode(entry, backedge) {
 188   }
 189 
 190   Node *init_control() const { return in(EntryControl); }
 191   Node *back_control() const { return in(LoopBackControl); }
 192 
 193   Node* init_trip() const;
 194   Node* stride() const;
 195   bool stride_is_con() const;
 196   Node* limit() const;
 197   Node* incr() const;
 198   Node* phi() const;
 199 
 200   BaseCountedLoopEndNode* loopexit_or_null() const;
 201   BaseCountedLoopEndNode* loopexit() const;
 202 
 203   virtual BasicType bt() const = 0;
 204 
 205   jlong stride_con() const;
 206 
 207   static BaseCountedLoopNode* make(Node* entry, Node* backedge, BasicType bt);
 208 };
 209 
 210 
 211 class CountedLoopNode : public BaseCountedLoopNode {
 212   // Size is bigger to hold _main_idx.  However, _main_idx does not change
 213   // the semantics so it does not appear in the hash & cmp functions.
 214   virtual uint size_of() const { return sizeof(*this); }
 215 
 216   // For Pre- and Post-loops during debugging ONLY, this holds the index of
 217   // the Main CountedLoop.  Used to assert that we understand the graph shape.
 218   node_idx_t _main_idx;
 219 
 220   // Known trip count calculated by compute_exact_trip_count()
 221   uint  _trip_count;
 222 
 223   // Log2 of original loop bodies in unrolled loop
 224   int _unrolled_count_log2;
 225 
 226   // Node count prior to last unrolling - used to decide if
 227   // unroll,optimize,unroll,optimize,... is making progress
 228   int _node_count_before_unroll;
 229 
 230   // If slp analysis is performed we record the maximum
 231   // vector mapped unroll factor here
 232   int _slp_maximum_unroll_factor;
 233 
 234   // The eventual count of vectorizable packs in slp
 235   int _slp_vector_pack_count;
 236 
 237 public:
 238   CountedLoopNode(Node *entry, Node *backedge)
 239     : BaseCountedLoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
 240       _unrolled_count_log2(0), _node_count_before_unroll(0),
 241       _slp_maximum_unroll_factor(0), _slp_vector_pack_count(0) {
 242     init_class_id(Class_CountedLoop);
 243     // Initialize _trip_count to the largest possible value.
 244     // Will be reset (lower) if the loop's trip count is known.
 245   }
 246 
 247   virtual int Opcode() const;
 248   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 249 
 250   CountedLoopEndNode* loopexit_or_null() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
 251   CountedLoopEndNode* loopexit() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
 252   int   stride_con() const;
 253 
 254   // Match increment with optional truncation
 255   static Node*
 256   match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInteger** trunc_type,
 257                                       BasicType bt);
 258 
 259   // A 'main' loop has a pre-loop and a post-loop.  The 'main' loop
 260   // can run short a few iterations and may start a few iterations in.
 261   // It will be RCE'd and unrolled and aligned.
 262 
 263   // A following 'post' loop will run any remaining iterations.  Used
 264   // during Range Check Elimination, the 'post' loop will do any final
 265   // iterations with full checks.  Also used by Loop Unrolling, where
 266   // the 'post' loop will do any epilog iterations needed.  Basically,
 267   // a 'post' loop can not profitably be further unrolled or RCE'd.
 268 
 269   // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
 270   // it may do under-flow checks for RCE and may do alignment iterations
 271   // so the following main loop 'knows' that it is striding down cache
 272   // lines.
 273 
 274   // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
 275   // Aligned, may be missing it's pre-loop.
 276   bool is_normal_loop   () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
 277   bool is_pre_loop      () const { return (_loop_flags&PreMainPostFlagsMask) == Pre;    }
 278   bool is_main_loop     () const { return (_loop_flags&PreMainPostFlagsMask) == Main;   }
 279   bool is_post_loop     () const { return (_loop_flags&PreMainPostFlagsMask) == Post;   }
 280   bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
 281   bool has_passed_slp   () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
 282   bool is_unroll_only   () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
 283   bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
 284   bool has_atomic_post_loop  () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
 285   void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
 286 
 287   int main_idx() const { return _main_idx; }
 288 
 289 
 290   void set_pre_loop  (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
 291   void set_main_loop (                     ) { assert(is_normal_loop(),""); _loop_flags |= Main;                         }
 292   void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
 293   void set_normal_loop(                    ) { _loop_flags &= ~PreMainPostFlagsMask; }
 294 
 295   void set_trip_count(uint tc) { _trip_count = tc; }
 296   uint trip_count()            { return _trip_count; }
 297 
 298   bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
 299   void set_exact_trip_count(uint tc) {
 300     _trip_count = tc;
 301     _loop_flags |= HasExactTripCount;
 302   }
 303   void set_nonexact_trip_count() {
 304     _loop_flags &= ~HasExactTripCount;
 305   }
 306   void set_notpassed_slp() {
 307     _loop_flags &= ~PassedSlpAnalysis;
 308   }
 309 
 310   void double_unrolled_count() { _unrolled_count_log2++; }
 311   int  unrolled_count()        { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
 312 
 313   void set_node_count_before_unroll(int ct)  { _node_count_before_unroll = ct; }
 314   int  node_count_before_unroll()            { return _node_count_before_unroll; }
 315   void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
 316   int  slp_max_unroll() const                { return _slp_maximum_unroll_factor; }
 317 
 318   virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
 319   OuterStripMinedLoopNode* outer_loop() const;
 320   virtual IfTrueNode* outer_loop_tail() const;
 321   virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
 322   virtual IfFalseNode* outer_loop_exit() const;
 323   virtual SafePointNode* outer_safepoint() const;
 324 
 325   // If this is a main loop in a pre/main/post loop nest, walk over
 326   // the predicates that were inserted by
 327   // duplicate_predicates()/add_range_check_predicate()
 328   static Node* skip_predicates_from_entry(Node* ctrl);
 329   Node* skip_predicates();
 330 
 331   virtual BasicType bt() const {
 332     return T_INT;
 333   }
 334 
 335   Node* is_canonical_loop_entry();
 336 
 337 #ifndef PRODUCT
 338   virtual void dump_spec(outputStream *st) const;
 339 #endif
 340 
 341   static bool is_zero_trip_guard_if(const IfNode* iff);
 342 };
 343 
 344 class LongCountedLoopNode : public BaseCountedLoopNode {
 345 public:
 346   LongCountedLoopNode(Node *entry, Node *backedge)
 347     : BaseCountedLoopNode(entry, backedge) {
 348     init_class_id(Class_LongCountedLoop);
 349   }
 350 
 351   virtual int Opcode() const;
 352 
 353   virtual BasicType bt() const {
 354     return T_LONG;
 355   }
 356 
 357   LongCountedLoopEndNode* loopexit_or_null() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
 358   LongCountedLoopEndNode* loopexit() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
 359 };
 360 
 361 
 362 //------------------------------CountedLoopEndNode-----------------------------
 363 // CountedLoopEndNodes end simple trip counted loops.  They act much like
 364 // IfNodes.
 365 
 366 class BaseCountedLoopEndNode : public IfNode {
 367 public:
 368   enum { TestControl, TestValue };
 369   BaseCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 370     : IfNode(control, test, prob, cnt) {
 371     init_class_id(Class_BaseCountedLoopEnd);
 372   }
 373 
 374   Node *cmp_node() const            { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : nullptr; }
 375   Node* incr() const                { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
 376   Node* limit() const               { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
 377   Node* stride() const              { Node* tmp = incr(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
 378   Node* init_trip() const           { Node* tmp = phi(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
 379   bool stride_is_con() const        { Node *tmp = stride(); return (tmp != nullptr && tmp->is_Con()); }
 380 
 381   PhiNode* phi() const {
 382     Node* tmp = incr();
 383     if (tmp && tmp->req() == 3) {
 384       Node* phi = tmp->in(1);
 385       if (phi->is_Phi()) {
 386         return phi->as_Phi();
 387       }
 388     }
 389     return nullptr;
 390   }
 391 
 392   BaseCountedLoopNode* loopnode() const {
 393     // The CountedLoopNode that goes with this CountedLoopEndNode may
 394     // have been optimized out by the IGVN so be cautious with the
 395     // pattern matching on the graph
 396     PhiNode* iv_phi = phi();
 397     if (iv_phi == nullptr) {
 398       return nullptr;
 399     }
 400     Node* ln = iv_phi->in(0);
 401     if (!ln->is_BaseCountedLoop() || ln->as_BaseCountedLoop()->loopexit_or_null() != this) {
 402       return nullptr;
 403     }
 404     if (ln->as_BaseCountedLoop()->bt() != bt()) {
 405       return nullptr;
 406     }
 407     return ln->as_BaseCountedLoop();
 408   }
 409 
 410   BoolTest::mask test_trip() const  { return in(TestValue)->as_Bool()->_test._test; }
 411 
 412   jlong stride_con() const;
 413   virtual BasicType bt() const = 0;
 414 
 415   static BaseCountedLoopEndNode* make(Node* control, Node* test, float prob, float cnt, BasicType bt);
 416 };
 417 
 418 class CountedLoopEndNode : public BaseCountedLoopEndNode {
 419 public:
 420 
 421   CountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 422     : BaseCountedLoopEndNode(control, test, prob, cnt) {
 423     init_class_id(Class_CountedLoopEnd);
 424   }
 425   virtual int Opcode() const;
 426 
 427   CountedLoopNode* loopnode() const {
 428     return (CountedLoopNode*) BaseCountedLoopEndNode::loopnode();
 429   }
 430 
 431   virtual BasicType bt() const {
 432     return T_INT;
 433   }
 434 
 435 #ifndef PRODUCT
 436   virtual void dump_spec(outputStream *st) const;
 437 #endif
 438 };
 439 
 440 class LongCountedLoopEndNode : public BaseCountedLoopEndNode {
 441 public:
 442   LongCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 443     : BaseCountedLoopEndNode(control, test, prob, cnt) {
 444     init_class_id(Class_LongCountedLoopEnd);
 445   }
 446 
 447   LongCountedLoopNode* loopnode() const {
 448     return (LongCountedLoopNode*) BaseCountedLoopEndNode::loopnode();
 449   }
 450 
 451   virtual int Opcode() const;
 452 
 453   virtual BasicType bt() const {
 454     return T_LONG;
 455   }
 456 };
 457 
 458 
 459 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit_or_null() const {
 460   Node* bctrl = back_control();
 461   if (bctrl == nullptr) return nullptr;
 462 
 463   Node* lexit = bctrl->in(0);
 464   if (!lexit->is_BaseCountedLoopEnd()) {
 465     return nullptr;
 466   }
 467   BaseCountedLoopEndNode* result = lexit->as_BaseCountedLoopEnd();
 468   if (result->bt() != bt()) {
 469     return nullptr;
 470   }
 471   return result;
 472 }
 473 
 474 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit() const {
 475   BaseCountedLoopEndNode* cle = loopexit_or_null();
 476   assert(cle != nullptr, "loopexit is null");
 477   return cle;
 478 }
 479 
 480 inline Node* BaseCountedLoopNode::init_trip() const {
 481   BaseCountedLoopEndNode* cle = loopexit_or_null();
 482   return cle != nullptr ? cle->init_trip() : nullptr;
 483 }
 484 inline Node* BaseCountedLoopNode::stride() const {
 485   BaseCountedLoopEndNode* cle = loopexit_or_null();
 486   return cle != nullptr ? cle->stride() : nullptr;
 487 }
 488 
 489 inline bool BaseCountedLoopNode::stride_is_con() const {
 490   BaseCountedLoopEndNode* cle = loopexit_or_null();
 491   return cle != nullptr && cle->stride_is_con();
 492 }
 493 inline Node* BaseCountedLoopNode::limit() const {
 494   BaseCountedLoopEndNode* cle = loopexit_or_null();
 495   return cle != nullptr ? cle->limit() : nullptr;
 496 }
 497 inline Node* BaseCountedLoopNode::incr() const {
 498   BaseCountedLoopEndNode* cle = loopexit_or_null();
 499   return cle != nullptr ? cle->incr() : nullptr;
 500 }
 501 inline Node* BaseCountedLoopNode::phi() const {
 502   BaseCountedLoopEndNode* cle = loopexit_or_null();
 503   return cle != nullptr ? cle->phi() : nullptr;
 504 }
 505 
 506 inline jlong BaseCountedLoopNode::stride_con() const {
 507   BaseCountedLoopEndNode* cle = loopexit_or_null();
 508   return cle != nullptr ? cle->stride_con() : 0;
 509 }
 510 
 511 
 512 //------------------------------LoopLimitNode-----------------------------
 513 // Counted Loop limit node which represents exact final iterator value:
 514 // trip_count = (limit - init_trip + stride - 1)/stride
 515 // final_value= trip_count * stride + init_trip.
 516 // Use HW instructions to calculate it when it can overflow in integer.
 517 // Note, final_value should fit into integer since counted loop has
 518 // limit check: limit <= max_int-stride.
 519 class LoopLimitNode : public Node {
 520   enum { Init=1, Limit=2, Stride=3 };
 521  public:
 522   LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
 523     // Put it on the Macro nodes list to optimize during macro nodes expansion.
 524     init_flags(Flag_is_macro);
 525     C->add_macro_node(this);
 526   }
 527   virtual int Opcode() const;
 528   virtual const Type *bottom_type() const { return TypeInt::INT; }
 529   virtual uint ideal_reg() const { return Op_RegI; }
 530   virtual const Type* Value(PhaseGVN* phase) const;
 531   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 532   virtual Node* Identity(PhaseGVN* phase);
 533 };
 534 
 535 // Support for strip mining
 536 class OuterStripMinedLoopNode : public LoopNode {
 537 private:
 538   static void fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
 539 
 540 public:
 541   OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
 542     : LoopNode(entry, backedge) {
 543     init_class_id(Class_OuterStripMinedLoop);
 544     init_flags(Flag_is_macro);
 545     C->add_macro_node(this);
 546   }
 547 
 548   virtual int Opcode() const;
 549 
 550   virtual IfTrueNode* outer_loop_tail() const;
 551   virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
 552   virtual IfFalseNode* outer_loop_exit() const;
 553   virtual SafePointNode* outer_safepoint() const;
 554   void adjust_strip_mined_loop(PhaseIterGVN* igvn);
 555 
 556   void remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const;
 557 
 558   void transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
 559 
 560   static Node* register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
 561 
 562   Node* register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
 563                          PhaseIdealLoop* iloop);
 564 };
 565 
 566 class OuterStripMinedLoopEndNode : public IfNode {
 567 public:
 568   OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 569     : IfNode(control, test, prob, cnt) {
 570     init_class_id(Class_OuterStripMinedLoopEnd);
 571   }
 572 
 573   virtual int Opcode() const;
 574 
 575   virtual const Type* Value(PhaseGVN* phase) const;
 576   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 577 
 578   bool is_expanded(PhaseGVN *phase) const;
 579 };
 580 
 581 // -----------------------------IdealLoopTree----------------------------------
 582 class IdealLoopTree : public ResourceObj {
 583 public:
 584   IdealLoopTree *_parent;       // Parent in loop tree
 585   IdealLoopTree *_next;         // Next sibling in loop tree
 586   IdealLoopTree *_child;        // First child in loop tree
 587 
 588   // The head-tail backedge defines the loop.
 589   // If a loop has multiple backedges, this is addressed during cleanup where
 590   // we peel off the multiple backedges,  merging all edges at the bottom and
 591   // ensuring that one proper backedge flow into the loop.
 592   Node *_head;                  // Head of loop
 593   Node *_tail;                  // Tail of loop
 594   inline Node *tail();          // Handle lazy update of _tail field
 595   inline Node *head();          // Handle lazy update of _head field
 596   PhaseIdealLoop* _phase;
 597   int _local_loop_unroll_limit;
 598   int _local_loop_unroll_factor;
 599 
 600   Node_List _body;              // Loop body for inner loops
 601 
 602   uint16_t _nest;               // Nesting depth
 603   uint8_t _irreducible:1,       // True if irreducible
 604           _has_call:1,          // True if has call safepoint
 605           _has_sfpt:1,          // True if has non-call safepoint
 606           _rce_candidate:1,     // True if candidate for range check elimination
 607           _has_range_checks:1,
 608           _has_range_checks_computed:1;
 609 
 610   Node_List* _safepts;          // List of safepoints in this loop
 611   Node_List* _required_safept;  // A inner loop cannot delete these safepts;
 612   bool  _allow_optimizations;   // Allow loop optimizations
 613 
 614   IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
 615     : _parent(0), _next(0), _child(0),
 616       _head(head), _tail(tail),
 617       _phase(phase),
 618       _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
 619       _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
 620       _has_range_checks(0), _has_range_checks_computed(0),
 621       _safepts(nullptr),
 622       _required_safept(nullptr),
 623       _allow_optimizations(true)
 624   {
 625     precond(_head != nullptr);
 626     precond(_tail != nullptr);
 627   }
 628 
 629   // Is 'l' a member of 'this'?
 630   bool is_member(const IdealLoopTree *l) const; // Test for nested membership
 631 
 632   // Set loop nesting depth.  Accumulate has_call bits.
 633   int set_nest( uint depth );
 634 
 635   // Split out multiple fall-in edges from the loop header.  Move them to a
 636   // private RegionNode before the loop.  This becomes the loop landing pad.
 637   void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
 638 
 639   // Split out the outermost loop from this shared header.
 640   void split_outer_loop( PhaseIdealLoop *phase );
 641 
 642   // Merge all the backedges from the shared header into a private Region.
 643   // Feed that region as the one backedge to this loop.
 644   void merge_many_backedges( PhaseIdealLoop *phase );
 645 
 646   // Split shared headers and insert loop landing pads.
 647   // Insert a LoopNode to replace the RegionNode.
 648   // Returns TRUE if loop tree is structurally changed.
 649   bool beautify_loops( PhaseIdealLoop *phase );
 650 
 651   // Perform optimization to use the loop predicates for null checks and range checks.
 652   // Applies to any loop level (not just the innermost one)
 653   bool loop_predication( PhaseIdealLoop *phase);
 654 
 655   // Perform iteration-splitting on inner loops.  Split iterations to
 656   // avoid range checks or one-shot null checks.  Returns false if the
 657   // current round of loop opts should stop.
 658   bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
 659 
 660   // Driver for various flavors of iteration splitting.  Returns false
 661   // if the current round of loop opts should stop.
 662   bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
 663 
 664   // Given dominators, try to find loops with calls that must always be
 665   // executed (call dominates loop tail).  These loops do not need non-call
 666   // safepoints (ncsfpt).
 667   void check_safepts(VectorSet &visited, Node_List &stack);
 668 
 669   // Allpaths backwards scan from loop tail, terminating each path at first safepoint
 670   // encountered.
 671   void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
 672 
 673   // Remove safepoints from loop. Optionally keeping one.
 674   void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
 675 
 676   // Convert to counted loops where possible
 677   void counted_loop( PhaseIdealLoop *phase );
 678 
 679   // Check for Node being a loop-breaking test
 680   Node *is_loop_exit(Node *iff) const;
 681 
 682   // Remove simplistic dead code from loop body
 683   void DCE_loop_body();
 684 
 685   // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
 686   // Replace with a 1-in-10 exit guess.
 687   void adjust_loop_exit_prob( PhaseIdealLoop *phase );
 688 
 689   // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
 690   // Useful for unrolling loops with NO array accesses.
 691   bool policy_peel_only( PhaseIdealLoop *phase ) const;
 692 
 693   // Return TRUE or FALSE if the loop should be unswitched -- clone
 694   // loop with an invariant test
 695   bool policy_unswitching( PhaseIdealLoop *phase ) const;
 696 
 697   // Micro-benchmark spamming.  Remove empty loops.
 698   bool do_remove_empty_loop( PhaseIdealLoop *phase );
 699 
 700   // Convert one iteration loop into normal code.
 701   bool do_one_iteration_loop( PhaseIdealLoop *phase );
 702 
 703   // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
 704   // move some loop-invariant test (usually a null-check) before the loop.
 705   bool policy_peeling(PhaseIdealLoop *phase);
 706 
 707   uint estimate_peeling(PhaseIdealLoop *phase);
 708 
 709   // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
 710   // known trip count in the counted loop node.
 711   bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
 712 
 713   // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
 714   // if the loop is a counted loop and the loop body is small enough.
 715   bool policy_unroll(PhaseIdealLoop *phase);
 716 
 717   // Loop analyses to map to a maximal superword unrolling for vectorization.
 718   void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
 719 
 720   // Return TRUE or FALSE if the loop should be range-check-eliminated.
 721   // Gather a list of IF tests that are dominated by iteration splitting;
 722   // also gather the end of the first split and the start of the 2nd split.
 723   bool policy_range_check(PhaseIdealLoop* phase, bool provisional, BasicType bt) const;
 724 
 725   // Return TRUE if "iff" is a range check.
 726   bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode* predicate_proj)) const;
 727   bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, BasicType bt, Node* iv, Node*& range, Node*& offset,
 728                          jlong& scale) const;
 729 
 730   // Estimate the number of nodes required when cloning a loop (body).
 731   uint est_loop_clone_sz(uint factor) const;
 732   // Estimate the number of nodes required when unrolling a loop (body).
 733   uint est_loop_unroll_sz(uint factor) const;
 734 
 735   // Compute loop trip count if possible
 736   void compute_trip_count(PhaseIdealLoop* phase);
 737 
 738   // Compute loop trip count from profile data
 739   float compute_profile_trip_cnt_helper(Node* n);
 740   void compute_profile_trip_cnt( PhaseIdealLoop *phase );
 741 
 742   // Reassociate invariant expressions.
 743   void reassociate_invariants(PhaseIdealLoop *phase);
 744   // Reassociate invariant binary expressions.
 745   Node* reassociate(Node* n1, PhaseIdealLoop *phase);
 746   // Reassociate invariant add and subtract expressions.
 747   Node* reassociate_add_sub(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop *phase);
 748   // Return nonzero index of invariant operand if invariant and variant
 749   // are combined with an associative binary. Helper for reassociate_invariants.
 750   int find_invariant(Node* n, PhaseIdealLoop *phase);
 751   // Return TRUE if "n" is associative.
 752   bool is_associative(Node* n, Node* base=nullptr);
 753 
 754   // Return true if n is invariant
 755   bool is_invariant(Node* n) const;
 756 
 757   // Put loop body on igvn work list
 758   void record_for_igvn();
 759 
 760   bool is_root() { return _parent == nullptr; }
 761   // A proper/reducible loop w/o any (occasional) dead back-edge.
 762   bool is_loop() { return !_irreducible && !tail()->is_top(); }
 763   bool is_counted()   { return is_loop() && _head->is_CountedLoop(); }
 764   bool is_innermost() { return is_loop() && _child == nullptr; }
 765 
 766   void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
 767 
 768   bool compute_has_range_checks() const;
 769   bool range_checks_present() {
 770     if (!_has_range_checks_computed) {
 771       if (compute_has_range_checks()) {
 772         _has_range_checks = 1;
 773       }
 774       _has_range_checks_computed = 1;
 775     }
 776     return _has_range_checks;
 777   }
 778 
 779 #ifndef PRODUCT
 780   void dump_head();       // Dump loop head only
 781   void dump();            // Dump this loop recursively
 782 #endif
 783 
 784 #ifdef ASSERT
 785   GrowableArray<IdealLoopTree*> collect_sorted_children() const;
 786   bool verify_tree(IdealLoopTree* loop_verify) const;
 787 #endif
 788 
 789  private:
 790   enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
 791 
 792   // Estimate the number of nodes resulting from control and data flow merge.
 793   uint est_loop_flow_merge_sz() const;
 794 
 795   // Check if the number of residual iterations is large with unroll_cnt.
 796   // Return true if the residual iterations are more than 10% of the trip count.
 797   bool is_residual_iters_large(int unroll_cnt, CountedLoopNode *cl) const {
 798     return (unroll_cnt - 1) * (100.0 / LoopPercentProfileLimit) > cl->profile_trip_cnt();
 799   }
 800 
 801   void collect_loop_core_nodes(PhaseIdealLoop* phase, Unique_Node_List& wq) const;
 802 
 803   bool empty_loop_with_data_nodes(PhaseIdealLoop* phase) const;
 804 
 805   void enqueue_data_nodes(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq) const;
 806 
 807   bool process_safepoint(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq,
 808                          Node* sfpt) const;
 809 
 810   bool empty_loop_candidate(PhaseIdealLoop* phase) const;
 811 
 812   bool empty_loop_with_extra_nodes_candidate(PhaseIdealLoop* phase) const;
 813 };
 814 
 815 // -----------------------------PhaseIdealLoop---------------------------------
 816 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees
 817 // into a loop tree. Drives the loop-based transformations on the ideal graph.
 818 class PhaseIdealLoop : public PhaseTransform {
 819   friend class IdealLoopTree;
 820   friend class SuperWord;
 821   friend class CountedLoopReserveKit;
 822   friend class ShenandoahBarrierC2Support;
 823   friend class AutoNodeBudget;
 824 
 825   // Map loop membership for CFG nodes, and ctrl for non-CFG nodes.
 826   Node_List _loop_or_ctrl;
 827 
 828   // Pre-computed def-use info
 829   PhaseIterGVN &_igvn;
 830 
 831   // Head of loop tree
 832   IdealLoopTree* _ltree_root;
 833 
 834   // Array of pre-order numbers, plus post-visited bit.
 835   // ZERO for not pre-visited.  EVEN for pre-visited but not post-visited.
 836   // ODD for post-visited.  Other bits are the pre-order number.
 837   uint *_preorders;
 838   uint _max_preorder;
 839 
 840   const PhaseIdealLoop* _verify_me;
 841   bool _verify_only;
 842 
 843   // Allocate _preorders[] array
 844   void allocate_preorders() {
 845     _max_preorder = C->unique()+8;
 846     _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
 847     memset(_preorders, 0, sizeof(uint) * _max_preorder);
 848   }
 849 
 850   // Allocate _preorders[] array
 851   void reallocate_preorders() {
 852     if ( _max_preorder < C->unique() ) {
 853       _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
 854       _max_preorder = C->unique();
 855     }
 856     memset(_preorders, 0, sizeof(uint) * _max_preorder);
 857   }
 858 
 859   // Check to grow _preorders[] array for the case when build_loop_tree_impl()
 860   // adds new nodes.
 861   void check_grow_preorders( ) {
 862     if ( _max_preorder < C->unique() ) {
 863       uint newsize = _max_preorder<<1;  // double size of array
 864       _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
 865       memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
 866       _max_preorder = newsize;
 867     }
 868   }
 869   // Check for pre-visited.  Zero for NOT visited; non-zero for visited.
 870   int is_visited( Node *n ) const { return _preorders[n->_idx]; }
 871   // Pre-order numbers are written to the Nodes array as low-bit-set values.
 872   void set_preorder_visited( Node *n, int pre_order ) {
 873     assert( !is_visited( n ), "already set" );
 874     _preorders[n->_idx] = (pre_order<<1);
 875   };
 876   // Return pre-order number.
 877   int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
 878 
 879   // Check for being post-visited.
 880   // Should be previsited already (checked with assert(is_visited(n))).
 881   int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
 882 
 883   // Mark as post visited
 884   void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
 885 
 886 public:
 887   // Set/get control node out.  Set lower bit to distinguish from IdealLoopTree
 888   // Returns true if "n" is a data node, false if it's a control node.
 889   bool has_ctrl(const Node* n) const { return ((intptr_t)_loop_or_ctrl[n->_idx]) & 1; }
 890 
 891 private:
 892   // clear out dead code after build_loop_late
 893   Node_List _deadlist;
 894   Node_List _zero_trip_guard_opaque_nodes;
 895 
 896   // Support for faster execution of get_late_ctrl()/dom_lca()
 897   // when a node has many uses and dominator depth is deep.
 898   GrowableArray<jlong> _dom_lca_tags;
 899   uint _dom_lca_tags_round;
 900   void   init_dom_lca_tags();
 901 
 902   // Helper for debugging bad dominance relationships
 903   bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
 904 
 905   Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
 906 
 907   // Inline wrapper for frequent cases:
 908   // 1) only one use
 909   // 2) a use is the same as the current LCA passed as 'n1'
 910   Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
 911     assert( n->is_CFG(), "" );
 912     // Fast-path null lca
 913     if( lca != nullptr && lca != n ) {
 914       assert( lca->is_CFG(), "" );
 915       // find LCA of all uses
 916       n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
 917     }
 918     return find_non_split_ctrl(n);
 919   }
 920   Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
 921 
 922   // Helper function for directing control inputs away from CFG split points.
 923   Node *find_non_split_ctrl( Node *ctrl ) const {
 924     if (ctrl != nullptr) {
 925       if (ctrl->is_MultiBranch()) {
 926         ctrl = ctrl->in(0);
 927       }
 928       assert(ctrl->is_CFG(), "CFG");
 929     }
 930     return ctrl;
 931   }
 932 
 933   Node* cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop);
 934 
 935 #ifdef ASSERT
 936   void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
 937 #endif
 938   void copy_assertion_predicates_to_main_loop_helper(Node* predicate, Node* init, Node* stride, IdealLoopTree* outer_loop,
 939                                                      LoopNode* outer_main_head, uint dd_main_head,
 940                                                      uint idx_before_pre_post, uint idx_after_post_before_pre,
 941                                                      Node* zero_trip_guard_proj_main, Node* zero_trip_guard_proj_post,
 942                                                      const Node_List &old_new);
 943   void copy_assertion_predicates_to_main_loop(CountedLoopNode* pre_head, Node* init, Node* stride, IdealLoopTree* outer_loop,
 944                                               LoopNode* outer_main_head, uint dd_main_head, uint idx_before_pre_post,
 945                                               uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
 946                                               Node* zero_trip_guard_proj_post, const Node_List& old_new);
 947   Node* clone_assertion_predicate_and_initialize(Node* iff, Node* new_init, Node* new_stride, Node* predicate,
 948                                                  Node* uncommon_proj, Node* control, IdealLoopTree* outer_loop,
 949                                                  Node* input_proj);
 950   static void count_opaque_loop_nodes(Node* n, uint& init, uint& stride);
 951   static bool subgraph_has_opaque(Node* n);
 952   Node* create_bool_from_template_assertion_predicate(Node* template_assertion_predicate, Node* new_init, Node* new_stride,
 953                                                       Node* control);
 954   static bool assertion_predicate_has_loop_opaque_node(IfNode* iff);
 955   static void get_assertion_predicates(Node* predicate, Unique_Node_List& list, bool get_opaque = false);
 956   void update_main_loop_assertion_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con);
 957   void copy_assertion_predicates_to_post_loop(LoopNode* main_loop_head, CountedLoopNode* post_loop_head, Node* init,
 958                                               Node* stride);
 959   void initialize_assertion_predicates_for_peeled_loop(IfProjNode* predicate_proj, LoopNode* outer_loop_head,
 960                                                        const int dd_outer_loop_head, Node* init, Node* stride,
 961                                                        IdealLoopTree* outer_loop, const uint idx_before_clone,
 962                                                        const Node_List& old_new);
 963   void insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj, Node* cmp_limit,
 964                                          Node* bol);
 965 #ifdef ASSERT
 966   bool only_has_infinite_loops();
 967 #endif
 968 
 969   void log_loop_tree();
 970 
 971 public:
 972 
 973   PhaseIterGVN &igvn() const { return _igvn; }
 974 
 975   bool has_node(const Node* n) const {
 976     guarantee(n != nullptr, "No Node.");
 977     return _loop_or_ctrl[n->_idx] != nullptr;
 978   }
 979   // check if transform created new nodes that need _ctrl recorded
 980   Node *get_late_ctrl( Node *n, Node *early );
 981   Node *get_early_ctrl( Node *n );
 982   Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
 983   void set_early_ctrl(Node* n, bool update_body);
 984   void set_subtree_ctrl(Node* n, bool update_body);
 985   void set_ctrl( Node *n, Node *ctrl ) {
 986     assert( !has_node(n) || has_ctrl(n), "" );
 987     assert( ctrl->in(0), "cannot set dead control node" );
 988     assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
 989     _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)ctrl + 1));
 990   }
 991   // Set control and update loop membership
 992   void set_ctrl_and_loop(Node* n, Node* ctrl) {
 993     IdealLoopTree* old_loop = get_loop(get_ctrl(n));
 994     IdealLoopTree* new_loop = get_loop(ctrl);
 995     if (old_loop != new_loop) {
 996       if (old_loop->_child == nullptr) old_loop->_body.yank(n);
 997       if (new_loop->_child == nullptr) new_loop->_body.push(n);
 998     }
 999     set_ctrl(n, ctrl);
1000   }
1001   // Control nodes can be replaced or subsumed.  During this pass they
1002   // get their replacement Node in slot 1.  Instead of updating the block
1003   // location of all Nodes in the subsumed block, we lazily do it.  As we
1004   // pull such a subsumed block out of the array, we write back the final
1005   // correct block.
1006   Node* get_ctrl(const Node* i) {
1007     assert(has_node(i), "");
1008     Node *n = get_ctrl_no_update(i);
1009     _loop_or_ctrl.map(i->_idx, (Node*)((intptr_t)n + 1));
1010     assert(has_node(i) && has_ctrl(i), "");
1011     assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
1012     return n;
1013   }
1014   // true if CFG node d dominates CFG node n
1015   bool is_dominator(Node *d, Node *n);
1016   // return get_ctrl for a data node and self(n) for a CFG node
1017   Node* ctrl_or_self(Node* n) {
1018     if (has_ctrl(n))
1019       return get_ctrl(n);
1020     else {
1021       assert (n->is_CFG(), "must be a CFG node");
1022       return n;
1023     }
1024   }
1025 
1026   Node* get_ctrl_no_update_helper(const Node* i) const {
1027     assert(has_ctrl(i), "should be control, not loop");
1028     return (Node*)(((intptr_t)_loop_or_ctrl[i->_idx]) & ~1);
1029   }
1030 
1031   Node* get_ctrl_no_update(const Node* i) const {
1032     assert( has_ctrl(i), "" );
1033     Node *n = get_ctrl_no_update_helper(i);
1034     if (!n->in(0)) {
1035       // Skip dead CFG nodes
1036       do {
1037         n = get_ctrl_no_update_helper(n);
1038       } while (!n->in(0));
1039       n = find_non_split_ctrl(n);
1040     }
1041     return n;
1042   }
1043 
1044   // Check for loop being set
1045   // "n" must be a control node. Returns true if "n" is known to be in a loop.
1046   bool has_loop( Node *n ) const {
1047     assert(!has_node(n) || !has_ctrl(n), "");
1048     return has_node(n);
1049   }
1050   // Set loop
1051   void set_loop( Node *n, IdealLoopTree *loop ) {
1052     _loop_or_ctrl.map(n->_idx, (Node*)loop);
1053   }
1054   // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms.  Replace
1055   // the 'old_node' with 'new_node'.  Kill old-node.  Add a reference
1056   // from old_node to new_node to support the lazy update.  Reference
1057   // replaces loop reference, since that is not needed for dead node.
1058   void lazy_update(Node *old_node, Node *new_node) {
1059     assert(old_node != new_node, "no cycles please");
1060     // Re-use the side array slot for this node to provide the
1061     // forwarding pointer.
1062     _loop_or_ctrl.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
1063   }
1064   void lazy_replace(Node *old_node, Node *new_node) {
1065     _igvn.replace_node(old_node, new_node);
1066     lazy_update(old_node, new_node);
1067   }
1068 
1069 private:
1070 
1071   // Place 'n' in some loop nest, where 'n' is a CFG node
1072   void build_loop_tree();
1073   int build_loop_tree_impl( Node *n, int pre_order );
1074   // Insert loop into the existing loop tree.  'innermost' is a leaf of the
1075   // loop tree, not the root.
1076   IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
1077 
1078 #ifdef ASSERT
1079   // verify that regions in irreducible loops are marked is_in_irreducible_loop
1080   void verify_regions_in_irreducible_loops();
1081   bool is_in_irreducible_loop(RegionNode* region);
1082 #endif
1083 
1084   // Place Data nodes in some loop nest
1085   void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1086   void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1087   void build_loop_late_post_work(Node* n, bool pinned);
1088   void build_loop_late_post(Node* n);
1089   void verify_strip_mined_scheduling(Node *n, Node* least);
1090 
1091   // Array of immediate dominance info for each CFG node indexed by node idx
1092 private:
1093   uint _idom_size;
1094   Node **_idom;                  // Array of immediate dominators
1095   uint *_dom_depth;              // Used for fast LCA test
1096   GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
1097   LoopOptsMode _mode;
1098 
1099   // build the loop tree and perform any requested optimizations
1100   void build_and_optimize();
1101 
1102   // Dominators for the sea of nodes
1103   void Dominators();
1104 
1105   // Compute the Ideal Node to Loop mapping
1106   PhaseIdealLoop(PhaseIterGVN& igvn, LoopOptsMode mode) :
1107     PhaseTransform(Ideal_Loop),
1108     _igvn(igvn),
1109     _verify_me(nullptr),
1110     _verify_only(false),
1111     _mode(mode),
1112     _nodes_required(UINT_MAX) {
1113     assert(mode != LoopOptsVerify, "wrong constructor to verify IdealLoop");
1114     build_and_optimize();
1115   }
1116 
1117 #ifndef PRODUCT
1118   // Verify that verify_me made the same decisions as a fresh run
1119   // or only verify that the graph is valid if verify_me is null.
1120   PhaseIdealLoop(PhaseIterGVN& igvn, const PhaseIdealLoop* verify_me = nullptr) :
1121     PhaseTransform(Ideal_Loop),
1122     _igvn(igvn),
1123     _verify_me(verify_me),
1124     _verify_only(verify_me == nullptr),
1125     _mode(LoopOptsVerify),
1126     _nodes_required(UINT_MAX) {
1127     build_and_optimize();
1128   }
1129 #endif
1130 
1131 public:
1132   Node* idom_no_update(Node* d) const {
1133     return idom_no_update(d->_idx);
1134   }
1135 
1136   Node* idom_no_update(uint didx) const {
1137     assert(didx < _idom_size, "oob");
1138     Node* n = _idom[didx];
1139     assert(n != nullptr,"Bad immediate dominator info.");
1140     while (n->in(0) == nullptr) { // Skip dead CFG nodes
1141       n = (Node*)(((intptr_t)_loop_or_ctrl[n->_idx]) & ~1);
1142       assert(n != nullptr,"Bad immediate dominator info.");
1143     }
1144     return n;
1145   }
1146 
1147   Node *idom(Node* d) const {
1148     return idom(d->_idx);
1149   }
1150 
1151   Node *idom(uint didx) const {
1152     Node *n = idom_no_update(didx);
1153     _idom[didx] = n; // Lazily remove dead CFG nodes from table.
1154     return n;
1155   }
1156 
1157   uint dom_depth(Node* d) const {
1158     guarantee(d != nullptr, "Null dominator info.");
1159     guarantee(d->_idx < _idom_size, "");
1160     return _dom_depth[d->_idx];
1161   }
1162   void set_idom(Node* d, Node* n, uint dom_depth);
1163   // Locally compute IDOM using dom_lca call
1164   Node *compute_idom( Node *region ) const;
1165   // Recompute dom_depth
1166   void recompute_dom_depth();
1167 
1168   // Is safept not required by an outer loop?
1169   bool is_deleteable_safept(Node* sfpt);
1170 
1171   // Replace parallel induction variable (parallel to trip counter)
1172   void replace_parallel_iv(IdealLoopTree *loop);
1173 
1174   Node *dom_lca( Node *n1, Node *n2 ) const {
1175     return find_non_split_ctrl(dom_lca_internal(n1, n2));
1176   }
1177   Node *dom_lca_internal( Node *n1, Node *n2 ) const;
1178 
1179   // Build and verify the loop tree without modifying the graph.  This
1180   // is useful to verify that all inputs properly dominate their uses.
1181   static void verify(PhaseIterGVN& igvn) {
1182 #ifdef ASSERT
1183     ResourceMark rm;
1184     Compile::TracePhase tp("idealLoopVerify", &timers[_t_idealLoopVerify]);
1185     PhaseIdealLoop v(igvn);
1186 #endif
1187   }
1188 
1189   // Recommended way to use PhaseIdealLoop.
1190   // Run PhaseIdealLoop in some mode and allocates a local scope for memory allocations.
1191   static void optimize(PhaseIterGVN &igvn, LoopOptsMode mode) {
1192     ResourceMark rm;
1193     PhaseIdealLoop v(igvn, mode);
1194 
1195     Compile* C = Compile::current();
1196     if (!C->failing()) {
1197       // Cleanup any modified bits
1198       igvn.optimize();
1199 
1200       v.log_loop_tree();
1201     }
1202   }
1203 
1204   // True if the method has at least 1 irreducible loop
1205   bool _has_irreducible_loops;
1206 
1207   // Per-Node transform
1208   virtual Node* transform(Node* n) { return nullptr; }
1209 
1210   Node* loop_exit_control(Node* x, IdealLoopTree* loop);
1211   Node* loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob);
1212   Node* loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr);
1213   Node* loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi);
1214   PhiNode* loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop);
1215 
1216   bool is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt);
1217 
1218   Node* loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head, BasicType bt);
1219   bool create_loop_nest(IdealLoopTree* loop, Node_List &old_new);
1220 #ifdef ASSERT
1221   bool convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop);
1222 #endif
1223   void add_parse_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, SafePointNode* sfpt);
1224   SafePointNode* find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop);
1225   IdealLoopTree* insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift);
1226   IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
1227                                                IdealLoopTree* loop, float cl_prob, float le_fcnt,
1228                                                Node*& entry_control, Node*& iffalse);
1229 
1230   Node* exact_limit( IdealLoopTree *loop );
1231 
1232   // Return a post-walked LoopNode
1233   IdealLoopTree *get_loop( Node *n ) const {
1234     // Dead nodes have no loop, so return the top level loop instead
1235     if (!has_node(n))  return _ltree_root;
1236     assert(!has_ctrl(n), "");
1237     return (IdealLoopTree*)_loop_or_ctrl[n->_idx];
1238   }
1239 
1240   IdealLoopTree* ltree_root() const { return _ltree_root; }
1241 
1242   // Is 'n' a (nested) member of 'loop'?
1243   int is_member( const IdealLoopTree *loop, Node *n ) const {
1244     return loop->is_member(get_loop(n)); }
1245 
1246   // This is the basic building block of the loop optimizations.  It clones an
1247   // entire loop body.  It makes an old_new loop body mapping; with this
1248   // mapping you can find the new-loop equivalent to an old-loop node.  All
1249   // new-loop nodes are exactly equal to their old-loop counterparts, all
1250   // edges are the same.  All exits from the old-loop now have a RegionNode
1251   // that merges the equivalent new-loop path.  This is true even for the
1252   // normal "loop-exit" condition.  All uses of loop-invariant old-loop values
1253   // now come from (one or more) Phis that merge their new-loop equivalents.
1254   // Parameter side_by_side_idom:
1255   //   When side_by_size_idom is null, the dominator tree is constructed for
1256   //      the clone loop to dominate the original.  Used in construction of
1257   //      pre-main-post loop sequence.
1258   //   When nonnull, the clone and original are side-by-side, both are
1259   //      dominated by the passed in side_by_side_idom node.  Used in
1260   //      construction of unswitched loops.
1261   enum CloneLoopMode {
1262     IgnoreStripMined = 0,        // Only clone inner strip mined loop
1263     CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops
1264     ControlAroundStripMined = 2  // Only clone inner strip mined loop,
1265                                  // result control flow branches
1266                                  // either to inner clone or outer
1267                                  // strip mined loop.
1268   };
1269   void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
1270                   CloneLoopMode mode, Node* side_by_side_idom = nullptr);
1271   void clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1272                                    IdealLoopTree* loop, IdealLoopTree* companion_loop,
1273                                    Node_List*& split_if_set, Node_List*& split_bool_set,
1274                                    Node_List*& split_cex_set, Node_List& worklist,
1275                                    uint new_counter, CloneLoopMode mode);
1276   void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1277                         IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1278                         Node_List& extra_data_nodes);
1279 
1280   // If we got the effect of peeling, either by actually peeling or by
1281   // making a pre-loop which must execute at least once, we can remove
1282   // all loop-invariant dominated tests in the main body.
1283   void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
1284 
1285   // Generate code to do a loop peel for the given loop (and body).
1286   // old_new is a temp array.
1287   void do_peeling( IdealLoopTree *loop, Node_List &old_new );
1288 
1289   // Add pre and post loops around the given loop.  These loops are used
1290   // during RCE, unrolling and aligning loops.
1291   void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
1292 
1293   // Add post loop after the given loop.
1294   Node *insert_post_loop(IdealLoopTree* loop, Node_List& old_new,
1295                          CountedLoopNode* main_head, CountedLoopEndNode* main_end,
1296                          Node*& incr, Node* limit, CountedLoopNode*& post_head);
1297 
1298   // Add a vector post loop between a vector main loop and the current post loop
1299   void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
1300   // If Node n lives in the back_ctrl block, we clone a private version of n
1301   // in preheader_ctrl block and return that, otherwise return n.
1302   Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
1303 
1304   // Take steps to maximally unroll the loop.  Peel any odd iterations, then
1305   // unroll to do double iterations.  The next round of major loop transforms
1306   // will repeat till the doubled loop body does all remaining iterations in 1
1307   // pass.
1308   void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
1309 
1310   // Unroll the loop body one step - make each trip do 2 iterations.
1311   void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
1312 
1313   // Return true if exp is a constant times an induction var
1314   bool is_scaled_iv(Node* exp, Node* iv, BasicType bt, jlong* p_scale, bool* p_short_scale, int depth = 0);
1315 
1316   bool is_iv(Node* exp, Node* iv, BasicType bt);
1317 
1318   // Return true if exp is a scaled induction var plus (or minus) constant
1319   bool is_scaled_iv_plus_offset(Node* exp, Node* iv, BasicType bt, jlong* p_scale, Node** p_offset, bool* p_short_scale = nullptr, int depth = 0);
1320   bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset) {
1321     jlong long_scale;
1322     if (is_scaled_iv_plus_offset(exp, iv, T_INT, &long_scale, p_offset)) {
1323       int int_scale = checked_cast<int>(long_scale);
1324       if (p_scale != nullptr) {
1325         *p_scale = int_scale;
1326       }
1327       return true;
1328     }
1329     return false;
1330   }
1331   // Helper for finding more complex matches to is_scaled_iv_plus_offset.
1332   bool is_scaled_iv_plus_extra_offset(Node* exp1, Node* offset2, Node* iv,
1333                                       BasicType bt,
1334                                       jlong* p_scale, Node** p_offset,
1335                                       bool* p_short_scale, int depth);
1336 
1337   // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
1338   IfProjNode* create_new_if_for_predicate(IfProjNode* cont_proj, Node* new_entry, Deoptimization::DeoptReason reason,
1339                                           int opcode, bool rewire_uncommon_proj_phi_inputs = false,
1340                                           bool if_cont_is_true_proj = true);
1341 
1342  private:
1343   // Helper functions for create_new_if_for_predicate()
1344   void set_ctrl_of_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl);
1345   Unique_Node_List find_nodes_with_same_ctrl(Node* node, const ProjNode* ctrl);
1346   Node* clone_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl);
1347   Dict clone_nodes(const Node_List& list_to_clone);
1348   void rewire_cloned_nodes_to_ctrl(const ProjNode* old_ctrl, Node* new_ctrl, const Node_List& nodes_with_same_ctrl,
1349                                    const Dict& old_new_mapping);
1350   void rewire_inputs_of_clones_to_clones(Node* new_ctrl, Node* clone, const Dict& old_new_mapping, const Node* next);
1351 
1352  public:
1353   void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
1354 
1355   // Construct a range check for a predicate if
1356   BoolNode* rc_predicate(IdealLoopTree* loop, Node* ctrl, int scale, Node* offset, Node* init, Node* limit,
1357                          jint stride, Node* range, bool upper, bool& overflow);
1358 
1359   // Implementation of the loop predication to promote checks outside the loop
1360   bool loop_predication_impl(IdealLoopTree *loop);
1361   bool loop_predication_impl_helper(IdealLoopTree* loop, IfProjNode* if_success_proj,
1362                                     ParsePredicateSuccessProj* parse_predicate_proj, CountedLoopNode* cl, ConNode* zero,
1363                                     Invariance& invar, Deoptimization::DeoptReason reason);
1364   bool loop_predication_should_follow_branches(IdealLoopTree* loop, IfProjNode* predicate_proj, float& loop_trip_cnt);
1365   void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt,
1366                                         PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1367                                         Node_List& if_proj_list);
1368   IfProjNode* add_template_assertion_predicate(IfNode* iff, IdealLoopTree* loop, IfProjNode* if_proj, IfProjNode* predicate_proj,
1369                                                IfProjNode* upper_bound_proj, int scale, Node* offset, Node* init, Node* limit,
1370                                                jint stride, Node* rng, bool& overflow, Deoptimization::DeoptReason reason);
1371   Node* add_range_check_elimination_assertion_predicate(IdealLoopTree* loop, Node* predicate_proj, int scale_con,
1372                                                         Node* offset, Node* limit, jint stride_con, Node* value);
1373 
1374   // Helper function to collect predicate for eliminating the useless ones
1375   void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1);
1376   void eliminate_useless_predicates();
1377   void eliminate_useless_zero_trip_guard();
1378 
1379   // Change the control input of expensive nodes to allow commoning by
1380   // IGVN when it is guaranteed to not result in a more frequent
1381   // execution of the expensive node. Return true if progress.
1382   bool process_expensive_nodes();
1383 
1384   // Check whether node has become unreachable
1385   bool is_node_unreachable(Node *n) const {
1386     return !has_node(n) || n->is_unreachable(_igvn);
1387   }
1388 
1389   // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1390   void do_range_check(IdealLoopTree *loop, Node_List &old_new);
1391 
1392   // Create a slow version of the loop by cloning the loop
1393   // and inserting an if to select fast-slow versions.
1394   // Return the inserted if.
1395   IfNode* create_slow_version_of_loop(IdealLoopTree *loop,
1396                                         Node_List &old_new,
1397                                         IfNode* unswitch_iff,
1398                                         CloneLoopMode mode);
1399 
1400   // Clone a loop and return the clone head (clone_loop_head).
1401   // Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse,
1402   // This routine was created for usage in CountedLoopReserveKit.
1403   //
1404   //    int(1) -> If -> IfTrue -> original_loop_head
1405   //              |
1406   //              V
1407   //           IfFalse -> clone_loop_head (returned by function pointer)
1408   //
1409   LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk);
1410   // Clone loop with an invariant test (that does not exit) and
1411   // insert a clone of the test that selects which version to
1412   // execute.
1413   void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
1414 
1415   // Find candidate "if" for unswitching
1416   IfNode* find_unswitching_candidate(const IdealLoopTree *loop) const;
1417 
1418   // Range Check Elimination uses this function!
1419   // Constrain the main loop iterations so the affine function:
1420   //    low_limit <= scale_con * I + offset  <  upper_limit
1421   // always holds true.  That is, either increase the number of iterations in
1422   // the pre-loop or the post-loop until the condition holds true in the main
1423   // loop.  Scale_con, offset and limit are all loop invariant.
1424   void add_constraint(jlong stride_con, jlong scale_con, Node* offset, Node* low_limit, Node* upper_limit, Node* pre_ctrl, Node** pre_limit, Node** main_limit);
1425   // Helper function for add_constraint().
1426   Node* adjust_limit(bool reduce, Node* scale, Node* offset, Node* rc_limit, Node* old_limit, Node* pre_ctrl, bool round);
1427 
1428   // Partially peel loop up through last_peel node.
1429   bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1430   bool duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new);
1431 
1432   // Move UnorderedReduction out of loop if possible
1433   void move_unordered_reduction_out_of_loop(IdealLoopTree* loop);
1434 
1435   // Create a scheduled list of nodes control dependent on ctrl set.
1436   void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1437   // Has a use in the vector set
1438   bool has_use_in_set( Node* n, VectorSet& vset );
1439   // Has use internal to the vector set (ie. not in a phi at the loop head)
1440   bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1441   // clone "n" for uses that are outside of loop
1442   int  clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1443   // clone "n" for special uses that are in the not_peeled region
1444   void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1445                                           VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1446   // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1447   void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1448 #ifdef ASSERT
1449   // Validate the loop partition sets: peel and not_peel
1450   bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1451   // Ensure that uses outside of loop are of the right form
1452   bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1453                                  uint orig_exit_idx, uint clone_exit_idx);
1454   bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1455 #endif
1456 
1457   // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1458   int stride_of_possible_iv( Node* iff );
1459   bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1460   // Return the (unique) control output node that's in the loop (if it exists.)
1461   Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1462   // Insert a signed compare loop exit cloned from an unsigned compare.
1463   IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1464   void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1465   // Utility to register node "n" with PhaseIdealLoop
1466   void register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth);
1467   // Utility to create an if-projection
1468   ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1469   // Force the iff control output to be the live_proj
1470   Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1471   // Insert a region before an if projection
1472   RegionNode* insert_region_before_proj(ProjNode* proj);
1473   // Insert a new if before an if projection
1474   ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1475 
1476   // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1477   // "Nearly" because all Nodes have been cloned from the original in the loop,
1478   // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1479   // through the Phi recursively, and return a Bool.
1480   Node* clone_iff(PhiNode* phi);
1481   CmpNode* clone_bool(PhiNode* phi);
1482 
1483 
1484   // Rework addressing expressions to get the most loop-invariant stuff
1485   // moved out.  We'd like to do all associative operators, but it's especially
1486   // important (common) to do address expressions.
1487   Node* remix_address_expressions(Node* n);
1488   Node* remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt);
1489 
1490   // Convert add to muladd to generate MuladdS2I under certain criteria
1491   Node * convert_add_to_muladd(Node * n);
1492 
1493   // Attempt to use a conditional move instead of a phi/branch
1494   Node *conditional_move( Node *n );
1495 
1496   // Check for aggressive application of 'split-if' optimization,
1497   // using basic block level info.
1498   void  split_if_with_blocks     ( VectorSet &visited, Node_Stack &nstack);
1499   Node *split_if_with_blocks_pre ( Node *n );
1500   void  split_if_with_blocks_post( Node *n );
1501   Node *has_local_phi_input( Node *n );
1502   // Mark an IfNode as being dominated by a prior test,
1503   // without actually altering the CFG (and hence IDOM info).
1504   void dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip = false, bool exclude_loop_predicate = false);
1505 
1506   // Split Node 'n' through merge point
1507   RegionNode* split_thru_region(Node* n, RegionNode* region);
1508   // Split Node 'n' through merge point if there is enough win.
1509   Node *split_thru_phi( Node *n, Node *region, int policy );
1510   // Found an If getting its condition-code input from a Phi in the
1511   // same block.  Split thru the Region.
1512   void do_split_if(Node *iff, RegionNode** new_false_region = nullptr, RegionNode** new_true_region = nullptr);
1513 
1514   // Conversion of fill/copy patterns into intrinsic versions
1515   bool do_intrinsify_fill();
1516   bool intrinsify_fill(IdealLoopTree* lpt);
1517   bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1518                        Node*& shift, Node*& offset);
1519 
1520 private:
1521   // Return a type based on condition control flow
1522   const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1523   const TypeInt* filtered_type( Node *n ) { return filtered_type(n, nullptr); }
1524  // Helpers for filtered type
1525   const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1526 
1527   // Helper functions
1528   Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1529   Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1530   void handle_use( Node *use, Node *def, small_cache *cache, Node *region_dom, Node *new_false, Node *new_true, Node *old_false, Node *old_true );
1531   bool split_up( Node *n, Node *blk1, Node *blk2 );
1532   void sink_use( Node *use, Node *post_loop );
1533   Node* place_outside_loop(Node* useblock, IdealLoopTree* loop) const;
1534   Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1535   void try_move_store_after_loop(Node* n);
1536   bool identical_backtoback_ifs(Node *n);
1537   bool can_split_if(Node *n_ctrl);
1538   bool cannot_split_division(const Node* n, const Node* region) const;
1539   static bool is_divisor_counted_loop_phi(const Node* divisor, const Node* loop);
1540   bool loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const;
1541 
1542   // Determine if a method is too big for a/another round of split-if, based on
1543   // a magic (approximate) ratio derived from the equally magic constant 35000,
1544   // previously used for this purpose (but without relating to the node limit).
1545   bool must_throttle_split_if() {
1546     uint threshold = C->max_node_limit() * 2 / 5;
1547     return C->live_nodes() > threshold;
1548   }
1549 
1550   // A simplistic node request tracking mechanism, where
1551   //   = UINT_MAX   Request not valid or made final.
1552   //   < UINT_MAX   Nodes currently requested (estimate).
1553   uint _nodes_required;
1554 
1555   enum { REQUIRE_MIN = 70 };
1556 
1557   uint nodes_required() const { return _nodes_required; }
1558 
1559   // Given the _currently_  available number of nodes, check  whether there is
1560   // "room" for an additional request or not, considering the already required
1561   // number of  nodes.  Return TRUE if  the new request is  exceeding the node
1562   // budget limit, otherwise return FALSE.  Note that this interpretation will
1563   // act pessimistic on  additional requests when new nodes  have already been
1564   // generated since the 'begin'.  This behaviour fits with the intention that
1565   // node estimates/requests should be made upfront.
1566   bool exceeding_node_budget(uint required = 0) {
1567     assert(C->live_nodes() < C->max_node_limit(), "sanity");
1568     uint available = C->max_node_limit() - C->live_nodes();
1569     return available < required + _nodes_required + REQUIRE_MIN;
1570   }
1571 
1572   uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1573     precond(require > 0);
1574     _nodes_required += MAX2(require, minreq);
1575     return _nodes_required;
1576   }
1577 
1578   bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1579     return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
1580   }
1581 
1582   uint require_nodes_begin() {
1583     assert(_nodes_required == UINT_MAX, "Bad state (begin).");
1584     _nodes_required = 0;
1585     return C->live_nodes();
1586   }
1587 
1588   // When a node request is final,  optionally check that the requested number
1589   // of nodes was  reasonably correct with respect to the  number of new nodes
1590   // introduced since the last 'begin'. Always check that we have not exceeded
1591   // the maximum node limit.
1592   void require_nodes_final(uint live_at_begin, bool check_estimate) {
1593     assert(_nodes_required < UINT_MAX, "Bad state (final).");
1594 
1595 #ifdef ASSERT
1596     if (check_estimate) {
1597       // Check that the node budget request was not off by too much (x2).
1598       // Should this be the case we _surely_ need to improve the estimates
1599       // used in our budget calculations.
1600       if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
1601         log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
1602                               C->live_nodes() - live_at_begin, _nodes_required);
1603       }
1604     }
1605 #endif
1606     // Assert that we have stayed within the node budget limit.
1607     assert(C->live_nodes() < C->max_node_limit(),
1608            "Exceeding node budget limit: %d + %d > %d (request = %d)",
1609            C->live_nodes() - live_at_begin, live_at_begin,
1610            C->max_node_limit(), _nodes_required);
1611 
1612     _nodes_required = UINT_MAX;
1613   }
1614 
1615   // Clone Parse Predicates to slow and fast loop when unswitching a loop
1616   void clone_parse_and_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, Node_List& old_new,
1617                                                                IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1618   IfProjNode* clone_parse_predicate_to_unswitched_loop(ParsePredicateSuccessProj* predicate_proj, Node* new_entry,
1619                                                        Deoptimization::DeoptReason reason, bool slow_loop);
1620   void clone_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1621                                                      Deoptimization::DeoptReason reason, IfProjNode* old_predicate_proj,
1622                                                      IfProjNode* iffast_pred, IfProjNode* ifslow_pred);
1623   IfProjNode* clone_assertion_predicate_for_unswitched_loops(Node* iff, IfProjNode* predicate,
1624                                                              Deoptimization::DeoptReason reason,
1625                                                              IfProjNode* output_proj);
1626   static void check_cloned_parse_predicate_for_unswitching(const Node* new_entry, bool is_fast_loop) PRODUCT_RETURN;
1627 
1628   bool _created_loop_node;
1629   DEBUG_ONLY(void dump_idoms(Node* early, Node* wrong_lca);)
1630   NOT_PRODUCT(void dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const;)
1631 
1632 public:
1633   void set_created_loop_node() { _created_loop_node = true; }
1634   bool created_loop_node()     { return _created_loop_node; }
1635   void register_new_node(Node* n, Node* blk);
1636 
1637 #ifdef ASSERT
1638   void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1639 #endif
1640 
1641 #ifndef PRODUCT
1642   void dump() const;
1643   void dump_idom(Node* n) const { dump_idom(n, 1000); } // For debugging
1644   void dump_idom(Node* n, uint count) const;
1645   void get_idoms(Node* n, uint count, Unique_Node_List& idoms) const;
1646   void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
1647   IdealLoopTree* get_loop_idx(Node* n) const {
1648     // Dead nodes have no loop, so return the top level loop instead
1649     return _loop_or_ctrl[n->_idx] ? (IdealLoopTree*)_loop_or_ctrl[n->_idx] : _ltree_root;
1650   }
1651   // Print some stats
1652   static void print_statistics();
1653   static int _loop_invokes;     // Count of PhaseIdealLoop invokes
1654   static int _loop_work;        // Sum of PhaseIdealLoop x _unique
1655   static volatile int _long_loop_candidates;
1656   static volatile int _long_loop_nests;
1657   static volatile int _long_loop_counted_loops;
1658 #endif
1659 
1660 #ifdef ASSERT
1661   void verify() const;
1662   bool verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const;
1663   bool verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const;
1664   bool verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const;
1665 #endif
1666 
1667   void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
1668 
1669   void check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) NOT_DEBUG_RETURN;
1670 
1671   LoopNode* create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, IfNode* exit_test);
1672 
1673 
1674   int extract_long_range_checks(const IdealLoopTree* loop, jlong stride_con, int iters_limit, PhiNode* phi,
1675                                       Node_List &range_checks);
1676 
1677   void transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1678                                    Node* inner_iters_actual_int, Node* inner_phi,
1679                                    Node* iv_add, LoopNode* inner_head);
1680 
1681   Node* get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA);
1682 
1683   bool ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl);
1684 
1685   bool ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop);
1686 
1687   Node* compute_early_ctrl(Node* n, Node* n_ctrl);
1688 
1689   void try_sink_out_of_loop(Node* n);
1690 
1691   Node* clamp(Node* R, Node* L, Node* H);
1692 
1693   bool safe_for_if_replacement(const Node* dom) const;
1694 
1695   void push_pinned_nodes_thru_region(IfNode* dom_if, Node* region);
1696 
1697   bool try_merge_identical_ifs(Node* n);
1698 
1699   void clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm);
1700 
1701   void fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
1702                       IdealLoopTree* parent, bool partial);
1703 
1704   void fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
1705                 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist);
1706 
1707   void fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
1708                      uint new_counter, Node_List& old_new, Node_List& worklist, Node_List*& split_if_set,
1709                      Node_List*& split_bool_set, Node_List*& split_cex_set);
1710 
1711   void finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set);
1712 
1713   bool clone_cmp_down(Node* n, const Node* blk1, const Node* blk2);
1714 
1715   void clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i);
1716 
1717   bool clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2);
1718 
1719   bool at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2);
1720 };
1721 
1722 
1723 class AutoNodeBudget : public StackObj
1724 {
1725 public:
1726   enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
1727 
1728   AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
1729     : _phase(phase),
1730       _check_at_final(chk == BUDGET_CHECK),
1731       _nodes_at_begin(0)
1732   {
1733     precond(_phase != nullptr);
1734 
1735     _nodes_at_begin = _phase->require_nodes_begin();
1736   }
1737 
1738   ~AutoNodeBudget() {
1739 #ifndef PRODUCT
1740     if (TraceLoopOpts) {
1741       uint request = _phase->nodes_required();
1742       uint delta   = _phase->C->live_nodes() - _nodes_at_begin;
1743 
1744       if (request < delta) {
1745         tty->print_cr("Exceeding node budget: %d < %d", request, delta);
1746       } else {
1747         uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
1748         // Identify the worst estimates as "poor" ones.
1749         if (request > REQUIRE_MIN && delta > 0) {
1750           if ((delta >  REQUIRE_MIN && request >  3 * delta) ||
1751               (delta <= REQUIRE_MIN && request > 10 * delta)) {
1752             tty->print_cr("Poor node estimate: %d >> %d", request, delta);
1753           }
1754         }
1755       }
1756     }
1757 #endif // PRODUCT
1758     _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
1759   }
1760 
1761 private:
1762   PhaseIdealLoop* _phase;
1763   bool _check_at_final;
1764   uint _nodes_at_begin;
1765 };
1766 
1767 
1768 // This kit may be used for making of a reserved copy of a loop before this loop
1769 //  goes under non-reversible changes.
1770 //
1771 // Function create_reserve() creates a reserved copy (clone) of the loop.
1772 // The reserved copy is created by calling
1773 // PhaseIdealLoop::create_reserve_version_of_loop - see there how
1774 // the original and reserved loops are connected in the outer graph.
1775 // If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'.
1776 //
1777 // By default the reserved copy (clone) of the loop is created as dead code - it is
1778 // dominated in the outer loop by this node chain:
1779 //   intcon(1)->If->IfFalse->reserved_copy.
1780 // The original loop is dominated by the same node chain but IfTrue projection:
1781 //   intcon(0)->If->IfTrue->original_loop.
1782 //
1783 // In this implementation of CountedLoopReserveKit the ctor includes create_reserve()
1784 // and the dtor, checks _use_new value.
1785 // If _use_new == false, it "switches" control to reserved copy of the loop
1786 // by simple replacing of node intcon(1) with node intcon(0).
1787 //
1788 // Here is a proposed example of usage (see also SuperWord::output in superword.cpp).
1789 //
1790 // void CountedLoopReserveKit_example()
1791 // {
1792 //    CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object
1793 //    if (DoReserveCopy && !lrk.has_reserved()) {
1794 //      return; //failed to create reserved loop copy
1795 //    }
1796 //    ...
1797 //    //something is wrong, switch to original loop
1798 ///   if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch
1799 //    ...
1800 //    //everything worked ok, return with the newly modified loop
1801 //    lrk.use_new();
1802 //    return; // ~CountedLoopReserveKit does nothing once use_new() was called
1803 //  }
1804 //
1805 // Keep in mind, that by default if create_reserve() is not followed by use_new()
1806 // the dtor will "switch to the original" loop.
1807 // NOTE. You you modify outside of the original loop this class is no help.
1808 //
1809 class CountedLoopReserveKit {
1810   private:
1811     PhaseIdealLoop* _phase;
1812     IdealLoopTree*  _lpt;
1813     LoopNode*       _lp;
1814     IfNode*         _iff;
1815     LoopNode*       _lp_reserved;
1816     bool            _has_reserved;
1817     bool            _use_new;
1818     const bool      _active; //may be set to false in ctor, then the object is dummy
1819 
1820   public:
1821     CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active);
1822     ~CountedLoopReserveKit();
1823     void use_new()                {_use_new = true;}
1824     void set_iff(IfNode* x)       {_iff = x;}
1825     bool has_reserved()     const { return _active && _has_reserved;}
1826   private:
1827     bool create_reserve();
1828 };// class CountedLoopReserveKit
1829 
1830 inline Node* IdealLoopTree::tail() {
1831   // Handle lazy update of _tail field.
1832   if (_tail->in(0) == nullptr) {
1833     _tail = _phase->get_ctrl(_tail);
1834   }
1835   return _tail;
1836 }
1837 
1838 inline Node* IdealLoopTree::head() {
1839   // Handle lazy update of _head field.
1840   if (_head->in(0) == nullptr) {
1841     _head = _phase->get_ctrl(_head);
1842   }
1843   return _head;
1844 }
1845 
1846 // Iterate over the loop tree using a preorder, left-to-right traversal.
1847 //
1848 // Example that visits all counted loops from within PhaseIdealLoop
1849 //
1850 //  for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1851 //   IdealLoopTree* lpt = iter.current();
1852 //   if (!lpt->is_counted()) continue;
1853 //   ...
1854 class LoopTreeIterator : public StackObj {
1855 private:
1856   IdealLoopTree* _root;
1857   IdealLoopTree* _curnt;
1858 
1859 public:
1860   LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1861 
1862   bool done() { return _curnt == nullptr; }       // Finished iterating?
1863 
1864   void next();                                 // Advance to next loop tree
1865 
1866   IdealLoopTree* current() { return _curnt; }  // Return current value of iterator.
1867 };
1868 
1869 // Compute probability of reaching some CFG node from a fixed
1870 // dominating CFG node
1871 class PathFrequency {
1872 private:
1873   Node* _dom; // frequencies are computed relative to this node
1874   Node_Stack _stack;
1875   GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
1876   GrowableArray<float> _freqs; // cache frequencies
1877   PhaseIdealLoop* _phase;
1878 
1879   float check_and_truncate_frequency(float f) {
1880     assert(f >= 0, "Incorrect frequency");
1881     // We do not perform an exact (f <= 1) check
1882     // this would be error prone with rounding of floats.
1883     // Performing a check like (f <= 1+eps) would be of benefit,
1884     // however, it is not evident how to determine such an eps,
1885     // given that an arbitrary number of add/mul operations
1886     // are performed on these frequencies.
1887     return (f > 1) ? 1 : f;
1888   }
1889 
1890 public:
1891   PathFrequency(Node* dom, PhaseIdealLoop* phase)
1892     : _dom(dom), _stack(0), _phase(phase) {
1893   }
1894 
1895   float to(Node* n);
1896 };
1897 
1898 // Utility class to work on predicates.
1899 class Predicates {
1900  public:
1901   static Node* skip_all_predicates(Node* node);
1902   static Node* skip_all_predicates(ParsePredicates& parse_predicates);
1903   static Node* skip_predicates_in_block(ParsePredicateSuccessProj* parse_predicate_success_proj);
1904   static IfProjNode* next_predicate_proj_in_block(IfProjNode* proj);
1905   static bool has_profiled_loop_predicates(ParsePredicates& parse_predicates);
1906 };
1907 
1908 // Class representing the Parse Predicates that are added during parsing with ParsePredicateNodes.
1909 class ParsePredicates {
1910  private:
1911   ParsePredicateSuccessProj* _loop_predicate_proj = nullptr;
1912   ParsePredicateSuccessProj* _profiled_loop_predicate_proj = nullptr;
1913   ParsePredicateSuccessProj* _loop_limit_check_predicate_proj = nullptr;
1914   // The success projection of the Parse Predicate that comes first when starting from root.
1915   ParsePredicateSuccessProj* _top_predicate_proj;
1916   ParsePredicateSuccessProj* _starting_proj;
1917 
1918   void find_parse_predicate_projections();
1919   static bool is_uct_proj(Node* node, Deoptimization::DeoptReason deopt_reason);
1920   static ParsePredicateNode* get_parse_predicate_or_null(Node* proj);
1921   bool assign_predicate_proj(ParsePredicateSuccessProj* parse_predicate_proj);
1922  public:
1923   ParsePredicates(Node* starting_proj);
1924 
1925   // Success projection of Loop Parse Predicate.
1926   ParsePredicateSuccessProj* loop_predicate_proj() {
1927     return _loop_predicate_proj;
1928   }
1929 
1930   // Success proj of Profiled Loop Parse Predicate.
1931   ParsePredicateSuccessProj* profiled_loop_predicate_proj() {
1932     return _profiled_loop_predicate_proj;
1933   }
1934 
1935   // Success proj of Loop Limit Check Parse Predicate.
1936   ParsePredicateSuccessProj* loop_limit_check_predicate_proj() {
1937     return _loop_limit_check_predicate_proj;
1938   }
1939 
1940   // Return the success projection of the Parse Predicate that comes first when starting from root.
1941   ParsePredicateSuccessProj* get_top_predicate_proj() {
1942     return _top_predicate_proj;
1943   }
1944 
1945   static bool is_success_proj(Node* node);
1946 
1947   // Are there any Parse Predicates?
1948   bool has_any() const {
1949     return _top_predicate_proj != nullptr;
1950   }
1951 
1952   static bool is_loop_limit_check_predicate_proj(Node* node) {
1953     ParsePredicateNode* parse_predicate = get_parse_predicate_or_null(node);
1954     return parse_predicate != nullptr && parse_predicate->deopt_reason() == Deoptimization::DeoptReason::Reason_loop_limit_check;
1955   }
1956 };
1957 #endif // SHARE_OPTO_LOOPNODE_HPP