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  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_OPTO_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          FlatArrays            = 1<<17};
  81   char _unswitch_count;
  82   enum { _unswitch_max=3 };
  83 
  84   // Expected trip count from profile data
  85   float _profile_trip_cnt;
  86 
  87 public:
  88   // Names for edge indices
  89   enum { Self=0, EntryControl, LoopBackControl };
  90 
  91   bool is_inner_loop() const { return _loop_flags & InnerLoop; }
  92   void set_inner_loop() { _loop_flags |= InnerLoop; }
  93 
  94   bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
  95   bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
  96   void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
  97   bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
  98   bool is_strip_mined() const { return _loop_flags & StripMined; }
  99   bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
 100   bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
 101   bool is_loop_nest_inner_loop() const { return _loop_flags & LoopNestInnerLoop; }
 102   bool is_loop_nest_outer_loop() const { return _loop_flags & LoopNestLongOuterLoop; }
 103   bool is_flat_arrays() const { return _loop_flags & FlatArrays; }
 104 
 105   void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
 106   void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
 107   void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
 108   void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
 109   void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
 110   void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
 111   void mark_strip_mined() { _loop_flags |= StripMined; }
 112   void clear_strip_mined() { _loop_flags &= ~StripMined; }
 113   void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
 114   void mark_subword_loop() { _loop_flags |= SubwordLoop; }
 115   void mark_loop_nest_inner_loop() { _loop_flags |= LoopNestInnerLoop; }
 116   void mark_loop_nest_outer_loop() { _loop_flags |= LoopNestLongOuterLoop; }
 117   void mark_flat_arrays() { _loop_flags |= FlatArrays; }
 118 
 119   int unswitch_max() { return _unswitch_max; }
 120   int unswitch_count() { return _unswitch_count; }
 121 
 122   void set_unswitch_count(int val) {
 123     assert (val <= unswitch_max(), "too many unswitches");
 124     _unswitch_count = val;
 125   }
 126 
 127   void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
 128   float profile_trip_cnt()             { return _profile_trip_cnt; }
 129 
 130   LoopNode(Node *entry, Node *backedge)
 131     : RegionNode(3), _loop_flags(0), _unswitch_count(0),
 132       _profile_trip_cnt(COUNT_UNKNOWN) {
 133     init_class_id(Class_Loop);
 134     init_req(EntryControl, entry);
 135     init_req(LoopBackControl, backedge);
 136   }
 137 
 138   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 139   virtual int Opcode() const;
 140   bool can_be_counted_loop(PhaseValues* phase) const {
 141     return req() == 3 && in(0) != nullptr &&
 142       in(1) != nullptr && phase->type(in(1)) != Type::TOP &&
 143       in(2) != nullptr && phase->type(in(2)) != Type::TOP;
 144   }
 145   bool is_valid_counted_loop(BasicType bt) const;
 146 #ifndef PRODUCT
 147   virtual void dump_spec(outputStream *st) const;
 148 #endif
 149 
 150   void verify_strip_mined(int expect_skeleton) const NOT_DEBUG_RETURN;
 151   virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; }
 152   virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return nullptr; }
 153   virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return nullptr; }
 154   virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return nullptr; }
 155   virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return nullptr; }
 156 };
 157 
 158 //------------------------------Counted Loops----------------------------------
 159 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
 160 // path (and maybe some other exit paths).  The trip-counter exit is always
 161 // last in the loop.  The trip-counter have to stride by a constant;
 162 // the exit value is also loop invariant.
 163 
 164 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs.  The
 165 // CountedLoopNode has the incoming loop control and the loop-back-control
 166 // which is always the IfTrue before the matching CountedLoopEndNode.  The
 167 // CountedLoopEndNode has an incoming control (possibly not the
 168 // CountedLoopNode if there is control flow in the loop), the post-increment
 169 // trip-counter value, and the limit.  The trip-counter value is always of
 170 // the form (Op old-trip-counter stride).  The old-trip-counter is produced
 171 // by a Phi connected to the CountedLoopNode.  The stride is constant.
 172 // The Op is any commutable opcode, including Add, Mul, Xor.  The
 173 // CountedLoopEndNode also takes in the loop-invariant limit value.
 174 
 175 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
 176 // loop-back control.  From CountedLoopEndNodes I can reach CountedLoopNodes
 177 // via the old-trip-counter from the Op node.
 178 
 179 //------------------------------CountedLoopNode--------------------------------
 180 // CountedLoopNodes head simple counted loops.  CountedLoopNodes have as
 181 // inputs the incoming loop-start control and the loop-back control, so they
 182 // act like RegionNodes.  They also take in the initial trip counter, the
 183 // loop-invariant stride and the loop-invariant limit value.  CountedLoopNodes
 184 // produce a loop-body control and the trip counter value.  Since
 185 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
 186 
 187 class BaseCountedLoopNode : public LoopNode {
 188 public:
 189   BaseCountedLoopNode(Node *entry, Node *backedge)
 190     : LoopNode(entry, backedge) {
 191   }
 192 
 193   Node *init_control() const { return in(EntryControl); }
 194   Node *back_control() const { return in(LoopBackControl); }
 195 
 196   Node* init_trip() const;
 197   Node* stride() const;
 198   bool stride_is_con() const;
 199   Node* limit() const;
 200   Node* incr() const;
 201   Node* phi() const;
 202 
 203   BaseCountedLoopEndNode* loopexit_or_null() const;
 204   BaseCountedLoopEndNode* loopexit() const;
 205 
 206   virtual BasicType bt() const = 0;
 207 
 208   jlong stride_con() const;
 209 
 210   static BaseCountedLoopNode* make(Node* entry, Node* backedge, BasicType bt);
 211 };
 212 
 213 
 214 class CountedLoopNode : public BaseCountedLoopNode {
 215   // Size is bigger to hold _main_idx.  However, _main_idx does not change
 216   // the semantics so it does not appear in the hash & cmp functions.
 217   virtual uint size_of() const { return sizeof(*this); }
 218 
 219   // For Pre- and Post-loops during debugging ONLY, this holds the index of
 220   // the Main CountedLoop.  Used to assert that we understand the graph shape.
 221   node_idx_t _main_idx;
 222 
 223   // Known trip count calculated by compute_exact_trip_count()
 224   uint  _trip_count;
 225 
 226   // Log2 of original loop bodies in unrolled loop
 227   int _unrolled_count_log2;
 228 
 229   // Node count prior to last unrolling - used to decide if
 230   // unroll,optimize,unroll,optimize,... is making progress
 231   int _node_count_before_unroll;
 232 
 233   // If slp analysis is performed we record the maximum
 234   // vector mapped unroll factor here
 235   int _slp_maximum_unroll_factor;
 236 
 237   // The eventual count of vectorizable packs in slp
 238   int _slp_vector_pack_count;
 239 
 240 public:
 241   CountedLoopNode(Node *entry, Node *backedge)
 242     : BaseCountedLoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
 243       _unrolled_count_log2(0), _node_count_before_unroll(0),
 244       _slp_maximum_unroll_factor(0), _slp_vector_pack_count(0) {
 245     init_class_id(Class_CountedLoop);
 246     // Initialize _trip_count to the largest possible value.
 247     // Will be reset (lower) if the loop's trip count is known.
 248   }
 249 
 250   virtual int Opcode() const;
 251   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 252 
 253   CountedLoopEndNode* loopexit_or_null() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
 254   CountedLoopEndNode* loopexit() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
 255   int   stride_con() const;
 256 
 257   // Match increment with optional truncation
 258   static Node*
 259   match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInteger** trunc_type,
 260                                       BasicType bt);
 261 
 262   // A 'main' loop has a pre-loop and a post-loop.  The 'main' loop
 263   // can run short a few iterations and may start a few iterations in.
 264   // It will be RCE'd and unrolled and aligned.
 265 
 266   // A following 'post' loop will run any remaining iterations.  Used
 267   // during Range Check Elimination, the 'post' loop will do any final
 268   // iterations with full checks.  Also used by Loop Unrolling, where
 269   // the 'post' loop will do any epilog iterations needed.  Basically,
 270   // a 'post' loop can not profitably be further unrolled or RCE'd.
 271 
 272   // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
 273   // it may do under-flow checks for RCE and may do alignment iterations
 274   // so the following main loop 'knows' that it is striding down cache
 275   // lines.
 276 
 277   // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
 278   // Aligned, may be missing it's pre-loop.
 279   bool is_normal_loop   () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
 280   bool is_pre_loop      () const { return (_loop_flags&PreMainPostFlagsMask) == Pre;    }
 281   bool is_main_loop     () const { return (_loop_flags&PreMainPostFlagsMask) == Main;   }
 282   bool is_post_loop     () const { return (_loop_flags&PreMainPostFlagsMask) == Post;   }
 283   bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
 284   bool has_passed_slp   () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
 285   bool is_unroll_only   () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
 286   bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
 287   bool has_atomic_post_loop  () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
 288   void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
 289 
 290   int main_idx() const { return _main_idx; }
 291 
 292 
 293   void set_pre_loop  (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
 294   void set_main_loop (                     ) { assert(is_normal_loop(),""); _loop_flags |= Main;                         }
 295   void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
 296   void set_normal_loop(                    ) { _loop_flags &= ~PreMainPostFlagsMask; }
 297 
 298   void set_trip_count(uint tc) { _trip_count = tc; }
 299   uint trip_count()            { return _trip_count; }
 300 
 301   bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
 302   void set_exact_trip_count(uint tc) {
 303     _trip_count = tc;
 304     _loop_flags |= HasExactTripCount;
 305   }
 306   void set_nonexact_trip_count() {
 307     _loop_flags &= ~HasExactTripCount;
 308   }
 309   void set_notpassed_slp() {
 310     _loop_flags &= ~PassedSlpAnalysis;
 311   }
 312 
 313   void double_unrolled_count() { _unrolled_count_log2++; }
 314   int  unrolled_count()        { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
 315 
 316   void set_node_count_before_unroll(int ct)  { _node_count_before_unroll = ct; }
 317   int  node_count_before_unroll()            { return _node_count_before_unroll; }
 318   void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
 319   int  slp_max_unroll() const                { return _slp_maximum_unroll_factor; }
 320 
 321   virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
 322   OuterStripMinedLoopNode* outer_loop() const;
 323   virtual IfTrueNode* outer_loop_tail() const;
 324   virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
 325   virtual IfFalseNode* outer_loop_exit() const;
 326   virtual SafePointNode* outer_safepoint() const;
 327 
 328   // If this is a main loop in a pre/main/post loop nest, walk over
 329   // the predicates that were inserted by
 330   // duplicate_predicates()/add_range_check_predicate()
 331   static Node* skip_predicates_from_entry(Node* ctrl);
 332   Node* skip_predicates();
 333 
 334   virtual BasicType bt() const {
 335     return T_INT;
 336   }
 337 
 338   Node* is_canonical_loop_entry();
 339 
 340 #ifndef PRODUCT
 341   virtual void dump_spec(outputStream *st) const;
 342 #endif
 343 
 344   static bool is_zero_trip_guard_if(const IfNode* iff);
 345 };
 346 
 347 class LongCountedLoopNode : public BaseCountedLoopNode {
 348 public:
 349   LongCountedLoopNode(Node *entry, Node *backedge)
 350     : BaseCountedLoopNode(entry, backedge) {
 351     init_class_id(Class_LongCountedLoop);
 352   }
 353 
 354   virtual int Opcode() const;
 355 
 356   virtual BasicType bt() const {
 357     return T_LONG;
 358   }
 359 
 360   LongCountedLoopEndNode* loopexit_or_null() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
 361   LongCountedLoopEndNode* loopexit() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
 362 };
 363 
 364 
 365 //------------------------------CountedLoopEndNode-----------------------------
 366 // CountedLoopEndNodes end simple trip counted loops.  They act much like
 367 // IfNodes.
 368 
 369 class BaseCountedLoopEndNode : public IfNode {
 370 public:
 371   enum { TestControl, TestValue };
 372   BaseCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 373     : IfNode(control, test, prob, cnt) {
 374     init_class_id(Class_BaseCountedLoopEnd);
 375   }
 376 
 377   Node *cmp_node() const            { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : nullptr; }
 378   Node* incr() const                { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
 379   Node* limit() const               { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
 380   Node* stride() const              { Node* tmp = incr(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
 381   Node* init_trip() const           { Node* tmp = phi(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
 382   bool stride_is_con() const        { Node *tmp = stride(); return (tmp != nullptr && tmp->is_Con()); }
 383 
 384   PhiNode* phi() const {
 385     Node* tmp = incr();
 386     if (tmp && tmp->req() == 3) {
 387       Node* phi = tmp->in(1);
 388       if (phi->is_Phi()) {
 389         return phi->as_Phi();
 390       }
 391     }
 392     return nullptr;
 393   }
 394 
 395   BaseCountedLoopNode* loopnode() const {
 396     // The CountedLoopNode that goes with this CountedLoopEndNode may
 397     // have been optimized out by the IGVN so be cautious with the
 398     // pattern matching on the graph
 399     PhiNode* iv_phi = phi();
 400     if (iv_phi == nullptr) {
 401       return nullptr;
 402     }
 403     Node* ln = iv_phi->in(0);
 404     if (!ln->is_BaseCountedLoop() || ln->as_BaseCountedLoop()->loopexit_or_null() != this) {
 405       return nullptr;
 406     }
 407     if (ln->as_BaseCountedLoop()->bt() != bt()) {
 408       return nullptr;
 409     }
 410     return ln->as_BaseCountedLoop();
 411   }
 412 
 413   BoolTest::mask test_trip() const  { return in(TestValue)->as_Bool()->_test._test; }
 414 
 415   jlong stride_con() const;
 416   virtual BasicType bt() const = 0;
 417 
 418   static BaseCountedLoopEndNode* make(Node* control, Node* test, float prob, float cnt, BasicType bt);
 419 };
 420 
 421 class CountedLoopEndNode : public BaseCountedLoopEndNode {
 422 public:
 423 
 424   CountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 425     : BaseCountedLoopEndNode(control, test, prob, cnt) {
 426     init_class_id(Class_CountedLoopEnd);
 427   }
 428   virtual int Opcode() const;
 429 
 430   CountedLoopNode* loopnode() const {
 431     return (CountedLoopNode*) BaseCountedLoopEndNode::loopnode();
 432   }
 433 
 434   virtual BasicType bt() const {
 435     return T_INT;
 436   }
 437 
 438 #ifndef PRODUCT
 439   virtual void dump_spec(outputStream *st) const;
 440 #endif
 441 };
 442 
 443 class LongCountedLoopEndNode : public BaseCountedLoopEndNode {
 444 public:
 445   LongCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 446     : BaseCountedLoopEndNode(control, test, prob, cnt) {
 447     init_class_id(Class_LongCountedLoopEnd);
 448   }
 449 
 450   LongCountedLoopNode* loopnode() const {
 451     return (LongCountedLoopNode*) BaseCountedLoopEndNode::loopnode();
 452   }
 453 
 454   virtual int Opcode() const;
 455 
 456   virtual BasicType bt() const {
 457     return T_LONG;
 458   }
 459 };
 460 
 461 
 462 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit_or_null() const {
 463   Node* bctrl = back_control();
 464   if (bctrl == nullptr) return nullptr;
 465 
 466   Node* lexit = bctrl->in(0);
 467   if (!lexit->is_BaseCountedLoopEnd()) {
 468     return nullptr;
 469   }
 470   BaseCountedLoopEndNode* result = lexit->as_BaseCountedLoopEnd();
 471   if (result->bt() != bt()) {
 472     return nullptr;
 473   }
 474   return result;
 475 }
 476 
 477 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit() const {
 478   BaseCountedLoopEndNode* cle = loopexit_or_null();
 479   assert(cle != nullptr, "loopexit is null");
 480   return cle;
 481 }
 482 
 483 inline Node* BaseCountedLoopNode::init_trip() const {
 484   BaseCountedLoopEndNode* cle = loopexit_or_null();
 485   return cle != nullptr ? cle->init_trip() : nullptr;
 486 }
 487 inline Node* BaseCountedLoopNode::stride() const {
 488   BaseCountedLoopEndNode* cle = loopexit_or_null();
 489   return cle != nullptr ? cle->stride() : nullptr;
 490 }
 491 
 492 inline bool BaseCountedLoopNode::stride_is_con() const {
 493   BaseCountedLoopEndNode* cle = loopexit_or_null();
 494   return cle != nullptr && cle->stride_is_con();
 495 }
 496 inline Node* BaseCountedLoopNode::limit() const {
 497   BaseCountedLoopEndNode* cle = loopexit_or_null();
 498   return cle != nullptr ? cle->limit() : nullptr;
 499 }
 500 inline Node* BaseCountedLoopNode::incr() const {
 501   BaseCountedLoopEndNode* cle = loopexit_or_null();
 502   return cle != nullptr ? cle->incr() : nullptr;
 503 }
 504 inline Node* BaseCountedLoopNode::phi() const {
 505   BaseCountedLoopEndNode* cle = loopexit_or_null();
 506   return cle != nullptr ? cle->phi() : nullptr;
 507 }
 508 
 509 inline jlong BaseCountedLoopNode::stride_con() const {
 510   BaseCountedLoopEndNode* cle = loopexit_or_null();
 511   return cle != nullptr ? cle->stride_con() : 0;
 512 }
 513 
 514 
 515 //------------------------------LoopLimitNode-----------------------------
 516 // Counted Loop limit node which represents exact final iterator value:
 517 // trip_count = (limit - init_trip + stride - 1)/stride
 518 // final_value= trip_count * stride + init_trip.
 519 // Use HW instructions to calculate it when it can overflow in integer.
 520 // Note, final_value should fit into integer since counted loop has
 521 // limit check: limit <= max_int-stride.
 522 class LoopLimitNode : public Node {
 523   enum { Init=1, Limit=2, Stride=3 };
 524  public:
 525   LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(0,init,limit,stride) {
 526     // Put it on the Macro nodes list to optimize during macro nodes expansion.
 527     init_flags(Flag_is_macro);
 528     C->add_macro_node(this);
 529   }
 530   virtual int Opcode() const;
 531   virtual const Type *bottom_type() const { return TypeInt::INT; }
 532   virtual uint ideal_reg() const { return Op_RegI; }
 533   virtual const Type* Value(PhaseGVN* phase) const;
 534   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 535   virtual Node* Identity(PhaseGVN* phase);
 536 };
 537 
 538 // Support for strip mining
 539 class OuterStripMinedLoopNode : public LoopNode {
 540 private:
 541   static void fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
 542 
 543 public:
 544   OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
 545     : LoopNode(entry, backedge) {
 546     init_class_id(Class_OuterStripMinedLoop);
 547     init_flags(Flag_is_macro);
 548     C->add_macro_node(this);
 549   }
 550 
 551   virtual int Opcode() const;
 552 
 553   virtual IfTrueNode* outer_loop_tail() const;
 554   virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
 555   virtual IfFalseNode* outer_loop_exit() const;
 556   virtual SafePointNode* outer_safepoint() const;
 557   void adjust_strip_mined_loop(PhaseIterGVN* igvn);
 558 
 559   void remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const;
 560 
 561   void transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
 562 
 563   static Node* register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
 564 
 565   Node* register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
 566                          PhaseIdealLoop* iloop);
 567 };
 568 
 569 class OuterStripMinedLoopEndNode : public IfNode {
 570 public:
 571   OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 572     : IfNode(control, test, prob, cnt) {
 573     init_class_id(Class_OuterStripMinedLoopEnd);
 574   }
 575 
 576   virtual int Opcode() const;
 577 
 578   virtual const Type* Value(PhaseGVN* phase) const;
 579   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 580 
 581   bool is_expanded(PhaseGVN *phase) const;
 582 };
 583 
 584 // -----------------------------IdealLoopTree----------------------------------
 585 class IdealLoopTree : public ResourceObj {
 586 public:
 587   IdealLoopTree *_parent;       // Parent in loop tree
 588   IdealLoopTree *_next;         // Next sibling in loop tree
 589   IdealLoopTree *_child;        // First child in loop tree
 590 
 591   // The head-tail backedge defines the loop.
 592   // If a loop has multiple backedges, this is addressed during cleanup where
 593   // we peel off the multiple backedges,  merging all edges at the bottom and
 594   // ensuring that one proper backedge flow into the loop.
 595   Node *_head;                  // Head of loop
 596   Node *_tail;                  // Tail of loop
 597   inline Node *tail();          // Handle lazy update of _tail field
 598   inline Node *head();          // Handle lazy update of _head field
 599   PhaseIdealLoop* _phase;
 600   int _local_loop_unroll_limit;
 601   int _local_loop_unroll_factor;
 602 
 603   Node_List _body;              // Loop body for inner loops
 604 
 605   uint16_t _nest;               // Nesting depth
 606   uint8_t _irreducible:1,       // True if irreducible
 607           _has_call:1,          // True if has call safepoint
 608           _has_sfpt:1,          // True if has non-call safepoint
 609           _rce_candidate:1,     // True if candidate for range check elimination
 610           _has_range_checks:1,
 611           _has_range_checks_computed:1;
 612 
 613   Node_List* _safepts;          // List of safepoints in this loop
 614   Node_List* _required_safept;  // A inner loop cannot delete these safepts;
 615   bool  _allow_optimizations;   // Allow loop optimizations
 616 
 617   IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
 618     : _parent(0), _next(0), _child(0),
 619       _head(head), _tail(tail),
 620       _phase(phase),
 621       _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
 622       _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
 623       _has_range_checks(0), _has_range_checks_computed(0),
 624       _safepts(nullptr),
 625       _required_safept(nullptr),
 626       _allow_optimizations(true)
 627   {
 628     precond(_head != nullptr);
 629     precond(_tail != nullptr);
 630   }
 631 
 632   // Is 'l' a member of 'this'?
 633   bool is_member(const IdealLoopTree *l) const; // Test for nested membership
 634 
 635   // Set loop nesting depth.  Accumulate has_call bits.
 636   int set_nest( uint depth );
 637 
 638   // Split out multiple fall-in edges from the loop header.  Move them to a
 639   // private RegionNode before the loop.  This becomes the loop landing pad.
 640   void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
 641 
 642   // Split out the outermost loop from this shared header.
 643   void split_outer_loop( PhaseIdealLoop *phase );
 644 
 645   // Merge all the backedges from the shared header into a private Region.
 646   // Feed that region as the one backedge to this loop.
 647   void merge_many_backedges( PhaseIdealLoop *phase );
 648 
 649   // Split shared headers and insert loop landing pads.
 650   // Insert a LoopNode to replace the RegionNode.
 651   // Returns TRUE if loop tree is structurally changed.
 652   bool beautify_loops( PhaseIdealLoop *phase );
 653 
 654   // Perform optimization to use the loop predicates for null checks and range checks.
 655   // Applies to any loop level (not just the innermost one)
 656   bool loop_predication( PhaseIdealLoop *phase);
 657 
 658   // Perform iteration-splitting on inner loops.  Split iterations to
 659   // avoid range checks or one-shot null checks.  Returns false if the
 660   // current round of loop opts should stop.
 661   bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
 662 
 663   // Driver for various flavors of iteration splitting.  Returns false
 664   // if the current round of loop opts should stop.
 665   bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
 666 
 667   // Given dominators, try to find loops with calls that must always be
 668   // executed (call dominates loop tail).  These loops do not need non-call
 669   // safepoints (ncsfpt).
 670   void check_safepts(VectorSet &visited, Node_List &stack);
 671 
 672   // Allpaths backwards scan from loop tail, terminating each path at first safepoint
 673   // encountered.
 674   void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
 675 
 676   // Remove safepoints from loop. Optionally keeping one.
 677   void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
 678 
 679   // Convert to counted loops where possible
 680   void counted_loop( PhaseIdealLoop *phase );
 681 
 682   // Check for Node being a loop-breaking test
 683   Node *is_loop_exit(Node *iff) const;
 684 
 685   // Remove simplistic dead code from loop body
 686   void DCE_loop_body();
 687 
 688   // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
 689   // Replace with a 1-in-10 exit guess.
 690   void adjust_loop_exit_prob( PhaseIdealLoop *phase );
 691 
 692   // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
 693   // Useful for unrolling loops with NO array accesses.
 694   bool policy_peel_only( PhaseIdealLoop *phase ) const;
 695 
 696   // Return TRUE or FALSE if the loop should be unswitched -- clone
 697   // loop with an invariant test
 698   bool policy_unswitching( PhaseIdealLoop *phase ) const;
 699 
 700   // Micro-benchmark spamming.  Remove empty loops.
 701   bool do_remove_empty_loop( PhaseIdealLoop *phase );
 702 
 703   // Convert one iteration loop into normal code.
 704   bool do_one_iteration_loop( PhaseIdealLoop *phase );
 705 
 706   // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
 707   // move some loop-invariant test (usually a null-check) before the loop.
 708   bool policy_peeling(PhaseIdealLoop *phase);
 709 
 710   uint estimate_peeling(PhaseIdealLoop *phase);
 711 
 712   // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
 713   // known trip count in the counted loop node.
 714   bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
 715 
 716   // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
 717   // if the loop is a counted loop and the loop body is small enough.
 718   bool policy_unroll(PhaseIdealLoop *phase);
 719 
 720   // Loop analyses to map to a maximal superword unrolling for vectorization.
 721   void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
 722 
 723   // Return TRUE or FALSE if the loop should be range-check-eliminated.
 724   // Gather a list of IF tests that are dominated by iteration splitting;
 725   // also gather the end of the first split and the start of the 2nd split.
 726   bool policy_range_check(PhaseIdealLoop* phase, bool provisional, BasicType bt) const;
 727 
 728   // Return TRUE if "iff" is a range check.
 729   bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode* predicate_proj)) const;
 730   bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, BasicType bt, Node* iv, Node*& range, Node*& offset,
 731                          jlong& scale) const;
 732 
 733   // Estimate the number of nodes required when cloning a loop (body).
 734   uint est_loop_clone_sz(uint factor) const;
 735   // Estimate the number of nodes required when unrolling a loop (body).
 736   uint est_loop_unroll_sz(uint factor) const;
 737 
 738   // Compute loop trip count if possible
 739   void compute_trip_count(PhaseIdealLoop* phase);
 740 
 741   // Compute loop trip count from profile data
 742   float compute_profile_trip_cnt_helper(Node* n);
 743   void compute_profile_trip_cnt( PhaseIdealLoop *phase );
 744 
 745   // Reassociate invariant expressions.
 746   void reassociate_invariants(PhaseIdealLoop *phase);
 747   // Reassociate invariant binary expressions.
 748   Node* reassociate(Node* n1, PhaseIdealLoop *phase);
 749   // Reassociate invariant add and subtract expressions.
 750   Node* reassociate_add_sub(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop *phase);
 751   // Return nonzero index of invariant operand if invariant and variant
 752   // are combined with an associative binary. Helper for reassociate_invariants.
 753   int find_invariant(Node* n, PhaseIdealLoop *phase);
 754   // Return TRUE if "n" is associative.
 755   bool is_associative(Node* n, Node* base=nullptr);
 756 
 757   // Return true if n is invariant
 758   bool is_invariant(Node* n) const;
 759 
 760   // Put loop body on igvn work list
 761   void record_for_igvn();
 762 
 763   bool is_root() { return _parent == nullptr; }
 764   // A proper/reducible loop w/o any (occasional) dead back-edge.
 765   bool is_loop() { return !_irreducible && !tail()->is_top(); }
 766   bool is_counted()   { return is_loop() && _head->is_CountedLoop(); }
 767   bool is_innermost() { return is_loop() && _child == nullptr; }
 768 
 769   void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
 770 
 771   bool compute_has_range_checks() const;
 772   bool range_checks_present() {
 773     if (!_has_range_checks_computed) {
 774       if (compute_has_range_checks()) {
 775         _has_range_checks = 1;
 776       }
 777       _has_range_checks_computed = 1;
 778     }
 779     return _has_range_checks;
 780   }
 781 
 782 #ifndef PRODUCT
 783   void dump_head();       // Dump loop head only
 784   void dump();            // Dump this loop recursively
 785 #endif
 786 
 787 #ifdef ASSERT
 788   GrowableArray<IdealLoopTree*> collect_sorted_children() const;
 789   bool verify_tree(IdealLoopTree* loop_verify) const;
 790 #endif
 791 
 792  private:
 793   enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
 794 
 795   // Estimate the number of nodes resulting from control and data flow merge.
 796   uint est_loop_flow_merge_sz() const;
 797 
 798   // Check if the number of residual iterations is large with unroll_cnt.
 799   // Return true if the residual iterations are more than 10% of the trip count.
 800   bool is_residual_iters_large(int unroll_cnt, CountedLoopNode *cl) const {
 801     return (unroll_cnt - 1) * (100.0 / LoopPercentProfileLimit) > cl->profile_trip_cnt();
 802   }
 803 
 804   void collect_loop_core_nodes(PhaseIdealLoop* phase, Unique_Node_List& wq) const;
 805 
 806   bool empty_loop_with_data_nodes(PhaseIdealLoop* phase) const;
 807 
 808   void enqueue_data_nodes(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq) const;
 809 
 810   bool process_safepoint(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq,
 811                          Node* sfpt) const;
 812 
 813   bool empty_loop_candidate(PhaseIdealLoop* phase) const;
 814 
 815   bool empty_loop_with_extra_nodes_candidate(PhaseIdealLoop* phase) const;
 816 };
 817 
 818 // -----------------------------PhaseIdealLoop---------------------------------
 819 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees
 820 // into a loop tree. Drives the loop-based transformations on the ideal graph.
 821 class PhaseIdealLoop : public PhaseTransform {
 822   friend class IdealLoopTree;
 823   friend class SuperWord;
 824   friend class CountedLoopReserveKit;
 825   friend class ShenandoahBarrierC2Support;
 826   friend class AutoNodeBudget;
 827 
 828   // Map loop membership for CFG nodes, and ctrl for non-CFG nodes.
 829   Node_List _loop_or_ctrl;
 830 
 831   // Pre-computed def-use info
 832   PhaseIterGVN &_igvn;
 833 
 834   // Head of loop tree
 835   IdealLoopTree* _ltree_root;
 836 
 837   // Array of pre-order numbers, plus post-visited bit.
 838   // ZERO for not pre-visited.  EVEN for pre-visited but not post-visited.
 839   // ODD for post-visited.  Other bits are the pre-order number.
 840   uint *_preorders;
 841   uint _max_preorder;
 842 
 843   const PhaseIdealLoop* _verify_me;
 844   bool _verify_only;
 845 
 846   // Allocate _preorders[] array
 847   void allocate_preorders() {
 848     _max_preorder = C->unique()+8;
 849     _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
 850     memset(_preorders, 0, sizeof(uint) * _max_preorder);
 851   }
 852 
 853   // Allocate _preorders[] array
 854   void reallocate_preorders() {
 855     if ( _max_preorder < C->unique() ) {
 856       _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
 857       _max_preorder = C->unique();
 858     }
 859     memset(_preorders, 0, sizeof(uint) * _max_preorder);
 860   }
 861 
 862   // Check to grow _preorders[] array for the case when build_loop_tree_impl()
 863   // adds new nodes.
 864   void check_grow_preorders( ) {
 865     if ( _max_preorder < C->unique() ) {
 866       uint newsize = _max_preorder<<1;  // double size of array
 867       _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
 868       memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
 869       _max_preorder = newsize;
 870     }
 871   }
 872   // Check for pre-visited.  Zero for NOT visited; non-zero for visited.
 873   int is_visited( Node *n ) const { return _preorders[n->_idx]; }
 874   // Pre-order numbers are written to the Nodes array as low-bit-set values.
 875   void set_preorder_visited( Node *n, int pre_order ) {
 876     assert( !is_visited( n ), "already set" );
 877     _preorders[n->_idx] = (pre_order<<1);
 878   };
 879   // Return pre-order number.
 880   int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
 881 
 882   // Check for being post-visited.
 883   // Should be previsited already (checked with assert(is_visited(n))).
 884   int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
 885 
 886   // Mark as post visited
 887   void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
 888 
 889 public:
 890   // Set/get control node out.  Set lower bit to distinguish from IdealLoopTree
 891   // Returns true if "n" is a data node, false if it's a control node.
 892   bool has_ctrl(const Node* n) const { return ((intptr_t)_loop_or_ctrl[n->_idx]) & 1; }
 893 
 894 private:
 895   // clear out dead code after build_loop_late
 896   Node_List _deadlist;
 897   Node_List _zero_trip_guard_opaque_nodes;
 898 
 899   // Support for faster execution of get_late_ctrl()/dom_lca()
 900   // when a node has many uses and dominator depth is deep.
 901   GrowableArray<jlong> _dom_lca_tags;
 902   uint _dom_lca_tags_round;
 903   void   init_dom_lca_tags();
 904 
 905   // Helper for debugging bad dominance relationships
 906   bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
 907 
 908   Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
 909 
 910   // Inline wrapper for frequent cases:
 911   // 1) only one use
 912   // 2) a use is the same as the current LCA passed as 'n1'
 913   Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
 914     assert( n->is_CFG(), "" );
 915     // Fast-path null lca
 916     if( lca != nullptr && lca != n ) {
 917       assert( lca->is_CFG(), "" );
 918       // find LCA of all uses
 919       n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
 920     }
 921     return find_non_split_ctrl(n);
 922   }
 923   Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
 924 
 925   // Helper function for directing control inputs away from CFG split points.
 926   Node *find_non_split_ctrl( Node *ctrl ) const {
 927     if (ctrl != nullptr) {
 928       if (ctrl->is_MultiBranch()) {
 929         ctrl = ctrl->in(0);
 930       }
 931       assert(ctrl->is_CFG(), "CFG");
 932     }
 933     return ctrl;
 934   }
 935 
 936   Node* cast_incr_before_loop(Node* incr, Node* ctrl, Node* loop);
 937 
 938 #ifdef ASSERT
 939   void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
 940 #endif
 941   void copy_assertion_predicates_to_main_loop_helper(Node* predicate, Node* init, Node* stride, IdealLoopTree* outer_loop,
 942                                                      LoopNode* outer_main_head, uint dd_main_head,
 943                                                      uint idx_before_pre_post, uint idx_after_post_before_pre,
 944                                                      Node* zero_trip_guard_proj_main, Node* zero_trip_guard_proj_post,
 945                                                      const Node_List &old_new);
 946   void copy_assertion_predicates_to_main_loop(CountedLoopNode* pre_head, Node* init, Node* stride, IdealLoopTree* outer_loop,
 947                                               LoopNode* outer_main_head, uint dd_main_head, uint idx_before_pre_post,
 948                                               uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
 949                                               Node* zero_trip_guard_proj_post, const Node_List& old_new);
 950   Node* clone_assertion_predicate_and_initialize(Node* iff, Node* new_init, Node* new_stride, Node* predicate,
 951                                                  Node* uncommon_proj, Node* control, IdealLoopTree* outer_loop,
 952                                                  Node* input_proj);
 953   static void count_opaque_loop_nodes(Node* n, uint& init, uint& stride);
 954   static bool subgraph_has_opaque(Node* n);
 955   Node* create_bool_from_template_assertion_predicate(Node* template_assertion_predicate, Node* new_init, Node* new_stride,
 956                                                       Node* control);
 957   static bool assertion_predicate_has_loop_opaque_node(IfNode* iff);
 958   static void get_assertion_predicates(Node* predicate, Unique_Node_List& list, bool get_opaque = false);
 959   void update_main_loop_assertion_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con);
 960   void copy_assertion_predicates_to_post_loop(LoopNode* main_loop_head, CountedLoopNode* post_loop_head, Node* init,
 961                                               Node* stride);
 962   void initialize_assertion_predicates_for_peeled_loop(IfProjNode* predicate_proj, LoopNode* outer_loop_head,
 963                                                        const int dd_outer_loop_head, Node* init, Node* stride,
 964                                                        IdealLoopTree* outer_loop, const uint idx_before_clone,
 965                                                        const Node_List& old_new);
 966   void insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj, Node* cmp_limit,
 967                                          Node* bol);
 968 #ifdef ASSERT
 969   bool only_has_infinite_loops();
 970 #endif
 971 
 972   void log_loop_tree();
 973 
 974 public:
 975 
 976   PhaseIterGVN &igvn() const { return _igvn; }
 977 
 978   bool has_node(const Node* n) const {
 979     guarantee(n != nullptr, "No Node.");
 980     return _loop_or_ctrl[n->_idx] != nullptr;
 981   }
 982   // check if transform created new nodes that need _ctrl recorded
 983   Node *get_late_ctrl( Node *n, Node *early );
 984   Node *get_early_ctrl( Node *n );
 985   Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
 986   void set_early_ctrl(Node* n, bool update_body);
 987   void set_subtree_ctrl(Node* n, bool update_body);
 988   void set_ctrl( Node *n, Node *ctrl ) {
 989     assert( !has_node(n) || has_ctrl(n), "" );
 990     assert( ctrl->in(0), "cannot set dead control node" );
 991     assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
 992     _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)ctrl + 1));
 993   }
 994   // Set control and update loop membership
 995   void set_ctrl_and_loop(Node* n, Node* ctrl) {
 996     IdealLoopTree* old_loop = get_loop(get_ctrl(n));
 997     IdealLoopTree* new_loop = get_loop(ctrl);
 998     if (old_loop != new_loop) {
 999       if (old_loop->_child == nullptr) old_loop->_body.yank(n);
1000       if (new_loop->_child == nullptr) new_loop->_body.push(n);
1001     }
1002     set_ctrl(n, ctrl);
1003   }
1004   // Control nodes can be replaced or subsumed.  During this pass they
1005   // get their replacement Node in slot 1.  Instead of updating the block
1006   // location of all Nodes in the subsumed block, we lazily do it.  As we
1007   // pull such a subsumed block out of the array, we write back the final
1008   // correct block.
1009   Node* get_ctrl(const Node* i) {
1010     assert(has_node(i), "");
1011     Node *n = get_ctrl_no_update(i);
1012     _loop_or_ctrl.map(i->_idx, (Node*)((intptr_t)n + 1));
1013     assert(has_node(i) && has_ctrl(i), "");
1014     assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
1015     return n;
1016   }
1017   // true if CFG node d dominates CFG node n
1018   bool is_dominator(Node *d, Node *n);
1019   // return get_ctrl for a data node and self(n) for a CFG node
1020   Node* ctrl_or_self(Node* n) {
1021     if (has_ctrl(n))
1022       return get_ctrl(n);
1023     else {
1024       assert (n->is_CFG(), "must be a CFG node");
1025       return n;
1026     }
1027   }
1028 
1029   Node* get_ctrl_no_update_helper(const Node* i) const {
1030     assert(has_ctrl(i), "should be control, not loop");
1031     return (Node*)(((intptr_t)_loop_or_ctrl[i->_idx]) & ~1);
1032   }
1033 
1034   Node* get_ctrl_no_update(const Node* i) const {
1035     assert( has_ctrl(i), "" );
1036     Node *n = get_ctrl_no_update_helper(i);
1037     if (!n->in(0)) {
1038       // Skip dead CFG nodes
1039       do {
1040         n = get_ctrl_no_update_helper(n);
1041       } while (!n->in(0));
1042       n = find_non_split_ctrl(n);
1043     }
1044     return n;
1045   }
1046 
1047   // Check for loop being set
1048   // "n" must be a control node. Returns true if "n" is known to be in a loop.
1049   bool has_loop( Node *n ) const {
1050     assert(!has_node(n) || !has_ctrl(n), "");
1051     return has_node(n);
1052   }
1053   // Set loop
1054   void set_loop( Node *n, IdealLoopTree *loop ) {
1055     _loop_or_ctrl.map(n->_idx, (Node*)loop);
1056   }
1057   // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms.  Replace
1058   // the 'old_node' with 'new_node'.  Kill old-node.  Add a reference
1059   // from old_node to new_node to support the lazy update.  Reference
1060   // replaces loop reference, since that is not needed for dead node.
1061   void lazy_update(Node *old_node, Node *new_node) {
1062     assert(old_node != new_node, "no cycles please");
1063     // Re-use the side array slot for this node to provide the
1064     // forwarding pointer.
1065     _loop_or_ctrl.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
1066   }
1067   void lazy_replace(Node *old_node, Node *new_node) {
1068     _igvn.replace_node(old_node, new_node);
1069     lazy_update(old_node, new_node);
1070   }
1071 
1072 private:
1073 
1074   // Place 'n' in some loop nest, where 'n' is a CFG node
1075   void build_loop_tree();
1076   int build_loop_tree_impl( Node *n, int pre_order );
1077   // Insert loop into the existing loop tree.  'innermost' is a leaf of the
1078   // loop tree, not the root.
1079   IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
1080 
1081 #ifdef ASSERT
1082   // verify that regions in irreducible loops are marked is_in_irreducible_loop
1083   void verify_regions_in_irreducible_loops();
1084   bool is_in_irreducible_loop(RegionNode* region);
1085 #endif
1086 
1087   // Place Data nodes in some loop nest
1088   void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1089   void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1090   void build_loop_late_post_work(Node* n, bool pinned);
1091   void build_loop_late_post(Node* n);
1092   void verify_strip_mined_scheduling(Node *n, Node* least);
1093 
1094   // Array of immediate dominance info for each CFG node indexed by node idx
1095 private:
1096   uint _idom_size;
1097   Node **_idom;                  // Array of immediate dominators
1098   uint *_dom_depth;              // Used for fast LCA test
1099   GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
1100   LoopOptsMode _mode;
1101 
1102   // build the loop tree and perform any requested optimizations
1103   void build_and_optimize();
1104 
1105   // Dominators for the sea of nodes
1106   void Dominators();
1107 
1108   // Compute the Ideal Node to Loop mapping
1109   PhaseIdealLoop(PhaseIterGVN& igvn, LoopOptsMode mode) :
1110     PhaseTransform(Ideal_Loop),
1111     _igvn(igvn),
1112     _verify_me(nullptr),
1113     _verify_only(false),
1114     _mode(mode),
1115     _nodes_required(UINT_MAX) {
1116     assert(mode != LoopOptsVerify, "wrong constructor to verify IdealLoop");
1117     build_and_optimize();
1118   }
1119 
1120 #ifndef PRODUCT
1121   // Verify that verify_me made the same decisions as a fresh run
1122   // or only verify that the graph is valid if verify_me is null.
1123   PhaseIdealLoop(PhaseIterGVN& igvn, const PhaseIdealLoop* verify_me = nullptr) :
1124     PhaseTransform(Ideal_Loop),
1125     _igvn(igvn),
1126     _verify_me(verify_me),
1127     _verify_only(verify_me == nullptr),
1128     _mode(LoopOptsVerify),
1129     _nodes_required(UINT_MAX) {
1130     build_and_optimize();
1131   }
1132 #endif
1133 
1134 public:
1135   Node* idom_no_update(Node* d) const {
1136     return idom_no_update(d->_idx);
1137   }
1138 
1139   Node* idom_no_update(uint didx) const {
1140     assert(didx < _idom_size, "oob");
1141     Node* n = _idom[didx];
1142     assert(n != nullptr,"Bad immediate dominator info.");
1143     while (n->in(0) == nullptr) { // Skip dead CFG nodes
1144       n = (Node*)(((intptr_t)_loop_or_ctrl[n->_idx]) & ~1);
1145       assert(n != nullptr,"Bad immediate dominator info.");
1146     }
1147     return n;
1148   }
1149 
1150   Node *idom(Node* d) const {
1151     return idom(d->_idx);
1152   }
1153 
1154   Node *idom(uint didx) const {
1155     Node *n = idom_no_update(didx);
1156     _idom[didx] = n; // Lazily remove dead CFG nodes from table.
1157     return n;
1158   }
1159 
1160   uint dom_depth(Node* d) const {
1161     guarantee(d != nullptr, "Null dominator info.");
1162     guarantee(d->_idx < _idom_size, "");
1163     return _dom_depth[d->_idx];
1164   }
1165   void set_idom(Node* d, Node* n, uint dom_depth);
1166   // Locally compute IDOM using dom_lca call
1167   Node *compute_idom( Node *region ) const;
1168   // Recompute dom_depth
1169   void recompute_dom_depth();
1170 
1171   // Is safept not required by an outer loop?
1172   bool is_deleteable_safept(Node* sfpt);
1173 
1174   // Replace parallel induction variable (parallel to trip counter)
1175   void replace_parallel_iv(IdealLoopTree *loop);
1176 
1177   Node *dom_lca( Node *n1, Node *n2 ) const {
1178     return find_non_split_ctrl(dom_lca_internal(n1, n2));
1179   }
1180   Node *dom_lca_internal( Node *n1, Node *n2 ) const;
1181 
1182   // Build and verify the loop tree without modifying the graph.  This
1183   // is useful to verify that all inputs properly dominate their uses.
1184   static void verify(PhaseIterGVN& igvn) {
1185 #ifdef ASSERT
1186     ResourceMark rm;
1187     Compile::TracePhase tp("idealLoopVerify", &timers[_t_idealLoopVerify]);
1188     PhaseIdealLoop v(igvn);
1189 #endif
1190   }
1191 
1192   // Recommended way to use PhaseIdealLoop.
1193   // Run PhaseIdealLoop in some mode and allocates a local scope for memory allocations.
1194   static void optimize(PhaseIterGVN &igvn, LoopOptsMode mode) {
1195     ResourceMark rm;
1196     PhaseIdealLoop v(igvn, mode);
1197 
1198     Compile* C = Compile::current();
1199     if (!C->failing()) {
1200       // Cleanup any modified bits
1201       igvn.optimize();
1202 
1203       v.log_loop_tree();
1204     }
1205   }
1206 
1207   // True if the method has at least 1 irreducible loop
1208   bool _has_irreducible_loops;
1209 
1210   // Per-Node transform
1211   virtual Node* transform(Node* n) { return nullptr; }
1212 
1213   Node* loop_exit_control(Node* x, IdealLoopTree* loop);
1214   Node* loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob);
1215   Node* loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr);
1216   Node* loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi);
1217   PhiNode* loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop);
1218 
1219   bool is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt);
1220 
1221   Node* loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head, BasicType bt);
1222   bool create_loop_nest(IdealLoopTree* loop, Node_List &old_new);
1223 #ifdef ASSERT
1224   bool convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop);
1225 #endif
1226   void add_parse_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, SafePointNode* sfpt);
1227   SafePointNode* find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop);
1228   IdealLoopTree* insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift);
1229   IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
1230                                                IdealLoopTree* loop, float cl_prob, float le_fcnt,
1231                                                Node*& entry_control, Node*& iffalse);
1232 
1233   Node* exact_limit( IdealLoopTree *loop );
1234 
1235   // Return a post-walked LoopNode
1236   IdealLoopTree *get_loop( Node *n ) const {
1237     // Dead nodes have no loop, so return the top level loop instead
1238     if (!has_node(n))  return _ltree_root;
1239     assert(!has_ctrl(n), "");
1240     return (IdealLoopTree*)_loop_or_ctrl[n->_idx];
1241   }
1242 
1243   IdealLoopTree* ltree_root() const { return _ltree_root; }
1244 
1245   // Is 'n' a (nested) member of 'loop'?
1246   int is_member( const IdealLoopTree *loop, Node *n ) const {
1247     return loop->is_member(get_loop(n)); }
1248 
1249   // This is the basic building block of the loop optimizations.  It clones an
1250   // entire loop body.  It makes an old_new loop body mapping; with this
1251   // mapping you can find the new-loop equivalent to an old-loop node.  All
1252   // new-loop nodes are exactly equal to their old-loop counterparts, all
1253   // edges are the same.  All exits from the old-loop now have a RegionNode
1254   // that merges the equivalent new-loop path.  This is true even for the
1255   // normal "loop-exit" condition.  All uses of loop-invariant old-loop values
1256   // now come from (one or more) Phis that merge their new-loop equivalents.
1257   // Parameter side_by_side_idom:
1258   //   When side_by_size_idom is null, the dominator tree is constructed for
1259   //      the clone loop to dominate the original.  Used in construction of
1260   //      pre-main-post loop sequence.
1261   //   When nonnull, the clone and original are side-by-side, both are
1262   //      dominated by the passed in side_by_side_idom node.  Used in
1263   //      construction of unswitched loops.
1264   enum CloneLoopMode {
1265     IgnoreStripMined = 0,        // Only clone inner strip mined loop
1266     CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops
1267     ControlAroundStripMined = 2  // Only clone inner strip mined loop,
1268                                  // result control flow branches
1269                                  // either to inner clone or outer
1270                                  // strip mined loop.
1271   };
1272   void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
1273                   CloneLoopMode mode, Node* side_by_side_idom = nullptr);
1274   void clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1275                                    IdealLoopTree* loop, IdealLoopTree* companion_loop,
1276                                    Node_List*& split_if_set, Node_List*& split_bool_set,
1277                                    Node_List*& split_cex_set, Node_List& worklist,
1278                                    uint new_counter, CloneLoopMode mode);
1279   void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1280                         IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1281                         Node_List& extra_data_nodes);
1282 
1283   // If we got the effect of peeling, either by actually peeling or by
1284   // making a pre-loop which must execute at least once, we can remove
1285   // all loop-invariant dominated tests in the main body.
1286   void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
1287 
1288   // Generate code to do a loop peel for the given loop (and body).
1289   // old_new is a temp array.
1290   void do_peeling( IdealLoopTree *loop, Node_List &old_new );
1291 
1292   // Add pre and post loops around the given loop.  These loops are used
1293   // during RCE, unrolling and aligning loops.
1294   void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
1295 
1296   // Add post loop after the given loop.
1297   Node *insert_post_loop(IdealLoopTree* loop, Node_List& old_new,
1298                          CountedLoopNode* main_head, CountedLoopEndNode* main_end,
1299                          Node*& incr, Node* limit, CountedLoopNode*& post_head);
1300 
1301   // Add a vector post loop between a vector main loop and the current post loop
1302   void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
1303   // If Node n lives in the back_ctrl block, we clone a private version of n
1304   // in preheader_ctrl block and return that, otherwise return n.
1305   Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
1306 
1307   // Take steps to maximally unroll the loop.  Peel any odd iterations, then
1308   // unroll to do double iterations.  The next round of major loop transforms
1309   // will repeat till the doubled loop body does all remaining iterations in 1
1310   // pass.
1311   void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
1312 
1313   // Unroll the loop body one step - make each trip do 2 iterations.
1314   void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
1315 
1316   // Return true if exp is a constant times an induction var
1317   bool is_scaled_iv(Node* exp, Node* iv, BasicType bt, jlong* p_scale, bool* p_short_scale, int depth = 0);
1318 
1319   bool is_iv(Node* exp, Node* iv, BasicType bt);
1320 
1321   // Return true if exp is a scaled induction var plus (or minus) constant
1322   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);
1323   bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset) {
1324     jlong long_scale;
1325     if (is_scaled_iv_plus_offset(exp, iv, T_INT, &long_scale, p_offset)) {
1326       int int_scale = checked_cast<int>(long_scale);
1327       if (p_scale != nullptr) {
1328         *p_scale = int_scale;
1329       }
1330       return true;
1331     }
1332     return false;
1333   }
1334   // Helper for finding more complex matches to is_scaled_iv_plus_offset.
1335   bool is_scaled_iv_plus_extra_offset(Node* exp1, Node* offset2, Node* iv,
1336                                       BasicType bt,
1337                                       jlong* p_scale, Node** p_offset,
1338                                       bool* p_short_scale, int depth);
1339 
1340   // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
1341   IfProjNode* create_new_if_for_predicate(IfProjNode* cont_proj, Node* new_entry, Deoptimization::DeoptReason reason,
1342                                           int opcode, bool rewire_uncommon_proj_phi_inputs = false,
1343                                           bool if_cont_is_true_proj = true);
1344 
1345  private:
1346   // Helper functions for create_new_if_for_predicate()
1347   void set_ctrl_of_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl);
1348   Unique_Node_List find_nodes_with_same_ctrl(Node* node, const ProjNode* ctrl);
1349   Node* clone_nodes_with_same_ctrl(Node* node, ProjNode* old_ctrl, Node* new_ctrl);
1350   Dict clone_nodes(const Node_List& list_to_clone);
1351   void rewire_cloned_nodes_to_ctrl(const ProjNode* old_ctrl, Node* new_ctrl, const Node_List& nodes_with_same_ctrl,
1352                                    const Dict& old_new_mapping);
1353   void rewire_inputs_of_clones_to_clones(Node* new_ctrl, Node* clone, const Dict& old_new_mapping, const Node* next);
1354 
1355  public:
1356   void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
1357 
1358   // Construct a range check for a predicate if
1359   BoolNode* rc_predicate(IdealLoopTree* loop, Node* ctrl, int scale, Node* offset, Node* init, Node* limit,
1360                          jint stride, Node* range, bool upper, bool& overflow);
1361 
1362   // Implementation of the loop predication to promote checks outside the loop
1363   bool loop_predication_impl(IdealLoopTree *loop);
1364   bool loop_predication_impl_helper(IdealLoopTree* loop, IfProjNode* if_success_proj,
1365                                     ParsePredicateSuccessProj* parse_predicate_proj, CountedLoopNode* cl, ConNode* zero,
1366                                     Invariance& invar, Deoptimization::DeoptReason reason);
1367   bool loop_predication_should_follow_branches(IdealLoopTree* loop, IfProjNode* predicate_proj, float& loop_trip_cnt);
1368   void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt,
1369                                         PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1370                                         Node_List& if_proj_list);
1371   IfProjNode* add_template_assertion_predicate(IfNode* iff, IdealLoopTree* loop, IfProjNode* if_proj, IfProjNode* predicate_proj,
1372                                                IfProjNode* upper_bound_proj, int scale, Node* offset, Node* init, Node* limit,
1373                                                jint stride, Node* rng, bool& overflow, Deoptimization::DeoptReason reason);
1374   Node* add_range_check_elimination_assertion_predicate(IdealLoopTree* loop, Node* predicate_proj, int scale_con,
1375                                                         Node* offset, Node* limit, jint stride_con, Node* value);
1376 
1377   // Helper function to collect predicate for eliminating the useless ones
1378   void collect_potentially_useful_predicates(IdealLoopTree *loop, Unique_Node_List &predicate_opaque1);
1379   void eliminate_useless_predicates();
1380   void eliminate_useless_zero_trip_guard();
1381 
1382   // Change the control input of expensive nodes to allow commoning by
1383   // IGVN when it is guaranteed to not result in a more frequent
1384   // execution of the expensive node. Return true if progress.
1385   bool process_expensive_nodes();
1386 
1387   // Check whether node has become unreachable
1388   bool is_node_unreachable(Node *n) const {
1389     return !has_node(n) || n->is_unreachable(_igvn);
1390   }
1391 
1392   // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1393   void do_range_check(IdealLoopTree *loop, Node_List &old_new);
1394 
1395   // Create a slow version of the loop by cloning the loop
1396   // and inserting an if to select fast-slow versions.
1397   // Return the inserted if.
1398   IfNode* create_slow_version_of_loop(IdealLoopTree *loop,
1399                                       Node_List &old_new,
1400                                       Node_List &unswitch_iffs,
1401                                       CloneLoopMode mode);
1402 
1403   // Clone a loop and return the clone head (clone_loop_head).
1404   // Added nodes include int(1), int(0) - disconnected, If, IfTrue, IfFalse,
1405   // This routine was created for usage in CountedLoopReserveKit.
1406   //
1407   //    int(1) -> If -> IfTrue -> original_loop_head
1408   //              |
1409   //              V
1410   //           IfFalse -> clone_loop_head (returned by function pointer)
1411   //
1412   LoopNode* create_reserve_version_of_loop(IdealLoopTree *loop, CountedLoopReserveKit* lk);
1413   // Clone loop with an invariant test (that does not exit) and
1414   // insert a clone of the test that selects which version to
1415   // execute.
1416   void do_unswitching (IdealLoopTree *loop, Node_List &old_new);
1417 
1418   // Find candidate "if" for unswitching
1419   IfNode* find_unswitching_candidate(const IdealLoopTree *loop, Node_List& unswitch_iffs) const;
1420 
1421   // Range Check Elimination uses this function!
1422   // Constrain the main loop iterations so the affine function:
1423   //    low_limit <= scale_con * I + offset  <  upper_limit
1424   // always holds true.  That is, either increase the number of iterations in
1425   // the pre-loop or the post-loop until the condition holds true in the main
1426   // loop.  Scale_con, offset and limit are all loop invariant.
1427   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);
1428   // Helper function for add_constraint().
1429   Node* adjust_limit(bool reduce, Node* scale, Node* offset, Node* rc_limit, Node* old_limit, Node* pre_ctrl, bool round);
1430 
1431   // Partially peel loop up through last_peel node.
1432   bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1433   bool duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new);
1434 
1435   // Move UnorderedReduction out of loop if possible
1436   void move_unordered_reduction_out_of_loop(IdealLoopTree* loop);
1437 
1438   // Create a scheduled list of nodes control dependent on ctrl set.
1439   void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1440   // Has a use in the vector set
1441   bool has_use_in_set( Node* n, VectorSet& vset );
1442   // Has use internal to the vector set (ie. not in a phi at the loop head)
1443   bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1444   // clone "n" for uses that are outside of loop
1445   int  clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1446   // clone "n" for special uses that are in the not_peeled region
1447   void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1448                                           VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1449   // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1450   void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1451 #ifdef ASSERT
1452   // Validate the loop partition sets: peel and not_peel
1453   bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1454   // Ensure that uses outside of loop are of the right form
1455   bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1456                                  uint orig_exit_idx, uint clone_exit_idx);
1457   bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1458 #endif
1459 
1460   // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1461   int stride_of_possible_iv( Node* iff );
1462   bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1463   // Return the (unique) control output node that's in the loop (if it exists.)
1464   Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1465   // Insert a signed compare loop exit cloned from an unsigned compare.
1466   IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1467   void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1468   // Utility to register node "n" with PhaseIdealLoop
1469   void register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth);
1470   // Utility to create an if-projection
1471   ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1472   // Force the iff control output to be the live_proj
1473   Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1474   // Insert a region before an if projection
1475   RegionNode* insert_region_before_proj(ProjNode* proj);
1476   // Insert a new if before an if projection
1477   ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1478 
1479   // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1480   // "Nearly" because all Nodes have been cloned from the original in the loop,
1481   // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1482   // through the Phi recursively, and return a Bool.
1483   Node* clone_iff(PhiNode* phi);
1484   CmpNode* clone_bool(PhiNode* phi);
1485 
1486 
1487   // Rework addressing expressions to get the most loop-invariant stuff
1488   // moved out.  We'd like to do all associative operators, but it's especially
1489   // important (common) to do address expressions.
1490   Node* remix_address_expressions(Node* n);
1491   Node* remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt);
1492 
1493   // Convert add to muladd to generate MuladdS2I under certain criteria
1494   Node * convert_add_to_muladd(Node * n);
1495 
1496   // Attempt to use a conditional move instead of a phi/branch
1497   Node *conditional_move( Node *n );
1498 
1499   // Check for aggressive application of 'split-if' optimization,
1500   // using basic block level info.
1501   void  split_if_with_blocks     ( VectorSet &visited, Node_Stack &nstack);
1502   Node *split_if_with_blocks_pre ( Node *n );
1503   void  split_if_with_blocks_post( Node *n );
1504   Node *has_local_phi_input( Node *n );
1505   // Mark an IfNode as being dominated by a prior test,
1506   // without actually altering the CFG (and hence IDOM info).
1507   void dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip = false, bool exclude_loop_predicate = false);
1508 
1509   // Split Node 'n' through merge point
1510   RegionNode* split_thru_region(Node* n, RegionNode* region);
1511   // Split Node 'n' through merge point if there is enough win.
1512   Node *split_thru_phi( Node *n, Node *region, int policy );
1513   // Found an If getting its condition-code input from a Phi in the
1514   // same block.  Split thru the Region.
1515   void do_split_if(Node *iff, RegionNode** new_false_region = nullptr, RegionNode** new_true_region = nullptr);
1516 
1517   // Conversion of fill/copy patterns into intrinsic versions
1518   bool do_intrinsify_fill();
1519   bool intrinsify_fill(IdealLoopTree* lpt);
1520   bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1521                        Node*& shift, Node*& offset);
1522 
1523 private:
1524   // Return a type based on condition control flow
1525   const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1526   const TypeInt* filtered_type( Node *n ) { return filtered_type(n, nullptr); }
1527  // Helpers for filtered type
1528   const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1529 
1530   // Helper functions
1531   Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1532   Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1533   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 );
1534   bool split_up( Node *n, Node *blk1, Node *blk2 );
1535   void sink_use( Node *use, Node *post_loop );
1536   Node* place_outside_loop(Node* useblock, IdealLoopTree* loop) const;
1537   Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1538   void try_move_store_after_loop(Node* n);
1539   void move_flat_array_check_out_of_loop(Node* n);
1540   bool identical_backtoback_ifs(Node *n);
1541   bool flat_array_element_type_check(Node *n);
1542   bool can_split_if(Node *n_ctrl);
1543   bool cannot_split_division(const Node* n, const Node* region) const;
1544   static bool is_divisor_counted_loop_phi(const Node* divisor, const Node* loop);
1545   bool loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const;
1546 
1547   // Determine if a method is too big for a/another round of split-if, based on
1548   // a magic (approximate) ratio derived from the equally magic constant 35000,
1549   // previously used for this purpose (but without relating to the node limit).
1550   bool must_throttle_split_if() {
1551     uint threshold = C->max_node_limit() * 2 / 5;
1552     return C->live_nodes() > threshold;
1553   }
1554 
1555   // A simplistic node request tracking mechanism, where
1556   //   = UINT_MAX   Request not valid or made final.
1557   //   < UINT_MAX   Nodes currently requested (estimate).
1558   uint _nodes_required;
1559 
1560   enum { REQUIRE_MIN = 70 };
1561 
1562   uint nodes_required() const { return _nodes_required; }
1563 
1564   // Given the _currently_  available number of nodes, check  whether there is
1565   // "room" for an additional request or not, considering the already required
1566   // number of  nodes.  Return TRUE if  the new request is  exceeding the node
1567   // budget limit, otherwise return FALSE.  Note that this interpretation will
1568   // act pessimistic on  additional requests when new nodes  have already been
1569   // generated since the 'begin'.  This behaviour fits with the intention that
1570   // node estimates/requests should be made upfront.
1571   bool exceeding_node_budget(uint required = 0) {
1572     assert(C->live_nodes() < C->max_node_limit(), "sanity");
1573     uint available = C->max_node_limit() - C->live_nodes();
1574     return available < required + _nodes_required + REQUIRE_MIN;
1575   }
1576 
1577   uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1578     precond(require > 0);
1579     _nodes_required += MAX2(require, minreq);
1580     return _nodes_required;
1581   }
1582 
1583   bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1584     return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
1585   }
1586 
1587   uint require_nodes_begin() {
1588     assert(_nodes_required == UINT_MAX, "Bad state (begin).");
1589     _nodes_required = 0;
1590     return C->live_nodes();
1591   }
1592 
1593   // When a node request is final,  optionally check that the requested number
1594   // of nodes was  reasonably correct with respect to the  number of new nodes
1595   // introduced since the last 'begin'. Always check that we have not exceeded
1596   // the maximum node limit.
1597   void require_nodes_final(uint live_at_begin, bool check_estimate) {
1598     assert(_nodes_required < UINT_MAX, "Bad state (final).");
1599 
1600 #ifdef ASSERT
1601     if (check_estimate) {
1602       // Check that the node budget request was not off by too much (x2).
1603       // Should this be the case we _surely_ need to improve the estimates
1604       // used in our budget calculations.
1605       if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
1606         log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
1607                               C->live_nodes() - live_at_begin, _nodes_required);
1608       }
1609     }
1610 #endif
1611     // Assert that we have stayed within the node budget limit.
1612     assert(C->live_nodes() < C->max_node_limit(),
1613            "Exceeding node budget limit: %d + %d > %d (request = %d)",
1614            C->live_nodes() - live_at_begin, live_at_begin,
1615            C->max_node_limit(), _nodes_required);
1616 
1617     _nodes_required = UINT_MAX;
1618   }
1619 
1620   // Clone Parse Predicates to slow and fast loop when unswitching a loop
1621   void clone_parse_and_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, Node_List& old_new,
1622                                                                IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1623   IfProjNode* clone_parse_predicate_to_unswitched_loop(ParsePredicateSuccessProj* predicate_proj, Node* new_entry,
1624                                                        Deoptimization::DeoptReason reason, bool slow_loop);
1625   void clone_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1626                                                      Deoptimization::DeoptReason reason, IfProjNode* old_predicate_proj,
1627                                                      IfProjNode* iffast_pred, IfProjNode* ifslow_pred);
1628   IfProjNode* clone_assertion_predicate_for_unswitched_loops(Node* iff, IfProjNode* predicate,
1629                                                              Deoptimization::DeoptReason reason,
1630                                                              IfProjNode* output_proj);
1631   static void check_cloned_parse_predicate_for_unswitching(const Node* new_entry, bool is_fast_loop) PRODUCT_RETURN;
1632 
1633   bool _created_loop_node;
1634   DEBUG_ONLY(void dump_idoms(Node* early, Node* wrong_lca);)
1635   NOT_PRODUCT(void dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const;)
1636 
1637 public:
1638   void set_created_loop_node() { _created_loop_node = true; }
1639   bool created_loop_node()     { return _created_loop_node; }
1640   void register_new_node(Node* n, Node* blk);
1641 
1642 #ifdef ASSERT
1643   void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1644 #endif
1645 
1646 #ifndef PRODUCT
1647   void dump() const;
1648   void dump_idom(Node* n) const { dump_idom(n, 1000); } // For debugging
1649   void dump_idom(Node* n, uint count) const;
1650   void get_idoms(Node* n, uint count, Unique_Node_List& idoms) const;
1651   void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
1652   IdealLoopTree* get_loop_idx(Node* n) const {
1653     // Dead nodes have no loop, so return the top level loop instead
1654     return _loop_or_ctrl[n->_idx] ? (IdealLoopTree*)_loop_or_ctrl[n->_idx] : _ltree_root;
1655   }
1656   // Print some stats
1657   static void print_statistics();
1658   static int _loop_invokes;     // Count of PhaseIdealLoop invokes
1659   static int _loop_work;        // Sum of PhaseIdealLoop x _unique
1660   static volatile int _long_loop_candidates;
1661   static volatile int _long_loop_nests;
1662   static volatile int _long_loop_counted_loops;
1663 #endif
1664 
1665 #ifdef ASSERT
1666   void verify() const;
1667   bool verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const;
1668   bool verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const;
1669   bool verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const;
1670 #endif
1671 
1672   void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
1673 
1674   void check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) NOT_DEBUG_RETURN;
1675 
1676   LoopNode* create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, IfNode* exit_test);
1677 
1678 
1679   int extract_long_range_checks(const IdealLoopTree* loop, jlong stride_con, int iters_limit, PhiNode* phi,
1680                                       Node_List &range_checks);
1681 
1682   void transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1683                                    Node* inner_iters_actual_int, Node* inner_phi,
1684                                    Node* iv_add, LoopNode* inner_head);
1685 
1686   Node* get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA);
1687 
1688   bool ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl);
1689 
1690   bool ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop);
1691 
1692   Node* compute_early_ctrl(Node* n, Node* n_ctrl);
1693 
1694   void try_sink_out_of_loop(Node* n);
1695 
1696   Node* clamp(Node* R, Node* L, Node* H);
1697 
1698   bool safe_for_if_replacement(const Node* dom) const;
1699 
1700   void push_pinned_nodes_thru_region(IfNode* dom_if, Node* region);
1701 
1702   bool try_merge_identical_ifs(Node* n);
1703 
1704   void clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm);
1705 
1706   void fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
1707                       IdealLoopTree* parent, bool partial);
1708 
1709   void fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
1710                 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist);
1711 
1712   void fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
1713                      uint new_counter, Node_List& old_new, Node_List& worklist, Node_List*& split_if_set,
1714                      Node_List*& split_bool_set, Node_List*& split_cex_set);
1715 
1716   void finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set);
1717 
1718   bool clone_cmp_down(Node* n, const Node* blk1, const Node* blk2);
1719 
1720   void clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i);
1721 
1722   bool clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2);
1723 
1724   bool at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2);
1725 };
1726 
1727 
1728 class AutoNodeBudget : public StackObj
1729 {
1730 public:
1731   enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
1732 
1733   AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
1734     : _phase(phase),
1735       _check_at_final(chk == BUDGET_CHECK),
1736       _nodes_at_begin(0)
1737   {
1738     precond(_phase != nullptr);
1739 
1740     _nodes_at_begin = _phase->require_nodes_begin();
1741   }
1742 
1743   ~AutoNodeBudget() {
1744 #ifndef PRODUCT
1745     if (TraceLoopOpts) {
1746       uint request = _phase->nodes_required();
1747       uint delta   = _phase->C->live_nodes() - _nodes_at_begin;
1748 
1749       if (request < delta) {
1750         tty->print_cr("Exceeding node budget: %d < %d", request, delta);
1751       } else {
1752         uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
1753         // Identify the worst estimates as "poor" ones.
1754         if (request > REQUIRE_MIN && delta > 0) {
1755           if ((delta >  REQUIRE_MIN && request >  3 * delta) ||
1756               (delta <= REQUIRE_MIN && request > 10 * delta)) {
1757             tty->print_cr("Poor node estimate: %d >> %d", request, delta);
1758           }
1759         }
1760       }
1761     }
1762 #endif // PRODUCT
1763     _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
1764   }
1765 
1766 private:
1767   PhaseIdealLoop* _phase;
1768   bool _check_at_final;
1769   uint _nodes_at_begin;
1770 };
1771 
1772 
1773 // This kit may be used for making of a reserved copy of a loop before this loop
1774 //  goes under non-reversible changes.
1775 //
1776 // Function create_reserve() creates a reserved copy (clone) of the loop.
1777 // The reserved copy is created by calling
1778 // PhaseIdealLoop::create_reserve_version_of_loop - see there how
1779 // the original and reserved loops are connected in the outer graph.
1780 // If create_reserve succeeded, it returns 'true' and _has_reserved is set to 'true'.
1781 //
1782 // By default the reserved copy (clone) of the loop is created as dead code - it is
1783 // dominated in the outer loop by this node chain:
1784 //   intcon(1)->If->IfFalse->reserved_copy.
1785 // The original loop is dominated by the same node chain but IfTrue projection:
1786 //   intcon(0)->If->IfTrue->original_loop.
1787 //
1788 // In this implementation of CountedLoopReserveKit the ctor includes create_reserve()
1789 // and the dtor, checks _use_new value.
1790 // If _use_new == false, it "switches" control to reserved copy of the loop
1791 // by simple replacing of node intcon(1) with node intcon(0).
1792 //
1793 // Here is a proposed example of usage (see also SuperWord::output in superword.cpp).
1794 //
1795 // void CountedLoopReserveKit_example()
1796 // {
1797 //    CountedLoopReserveKit lrk((phase, lpt, DoReserveCopy = true); // create local object
1798 //    if (DoReserveCopy && !lrk.has_reserved()) {
1799 //      return; //failed to create reserved loop copy
1800 //    }
1801 //    ...
1802 //    //something is wrong, switch to original loop
1803 ///   if(something_is_wrong) return; // ~CountedLoopReserveKit makes the switch
1804 //    ...
1805 //    //everything worked ok, return with the newly modified loop
1806 //    lrk.use_new();
1807 //    return; // ~CountedLoopReserveKit does nothing once use_new() was called
1808 //  }
1809 //
1810 // Keep in mind, that by default if create_reserve() is not followed by use_new()
1811 // the dtor will "switch to the original" loop.
1812 // NOTE. You you modify outside of the original loop this class is no help.
1813 //
1814 class CountedLoopReserveKit {
1815   private:
1816     PhaseIdealLoop* _phase;
1817     IdealLoopTree*  _lpt;
1818     LoopNode*       _lp;
1819     IfNode*         _iff;
1820     LoopNode*       _lp_reserved;
1821     bool            _has_reserved;
1822     bool            _use_new;
1823     const bool      _active; //may be set to false in ctor, then the object is dummy
1824 
1825   public:
1826     CountedLoopReserveKit(PhaseIdealLoop* phase, IdealLoopTree *loop, bool active);
1827     ~CountedLoopReserveKit();
1828     void use_new()                {_use_new = true;}
1829     void set_iff(IfNode* x)       {_iff = x;}
1830     bool has_reserved()     const { return _active && _has_reserved;}
1831   private:
1832     bool create_reserve();
1833 };// class CountedLoopReserveKit
1834 
1835 inline Node* IdealLoopTree::tail() {
1836   // Handle lazy update of _tail field.
1837   if (_tail->in(0) == nullptr) {
1838     _tail = _phase->get_ctrl(_tail);
1839   }
1840   return _tail;
1841 }
1842 
1843 inline Node* IdealLoopTree::head() {
1844   // Handle lazy update of _head field.
1845   if (_head->in(0) == nullptr) {
1846     _head = _phase->get_ctrl(_head);
1847   }
1848   return _head;
1849 }
1850 
1851 // Iterate over the loop tree using a preorder, left-to-right traversal.
1852 //
1853 // Example that visits all counted loops from within PhaseIdealLoop
1854 //
1855 //  for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1856 //   IdealLoopTree* lpt = iter.current();
1857 //   if (!lpt->is_counted()) continue;
1858 //   ...
1859 class LoopTreeIterator : public StackObj {
1860 private:
1861   IdealLoopTree* _root;
1862   IdealLoopTree* _curnt;
1863 
1864 public:
1865   LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1866 
1867   bool done() { return _curnt == nullptr; }       // Finished iterating?
1868 
1869   void next();                                 // Advance to next loop tree
1870 
1871   IdealLoopTree* current() { return _curnt; }  // Return current value of iterator.
1872 };
1873 
1874 // Compute probability of reaching some CFG node from a fixed
1875 // dominating CFG node
1876 class PathFrequency {
1877 private:
1878   Node* _dom; // frequencies are computed relative to this node
1879   Node_Stack _stack;
1880   GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
1881   GrowableArray<float> _freqs; // cache frequencies
1882   PhaseIdealLoop* _phase;
1883 
1884   float check_and_truncate_frequency(float f) {
1885     assert(f >= 0, "Incorrect frequency");
1886     // We do not perform an exact (f <= 1) check
1887     // this would be error prone with rounding of floats.
1888     // Performing a check like (f <= 1+eps) would be of benefit,
1889     // however, it is not evident how to determine such an eps,
1890     // given that an arbitrary number of add/mul operations
1891     // are performed on these frequencies.
1892     return (f > 1) ? 1 : f;
1893   }
1894 
1895 public:
1896   PathFrequency(Node* dom, PhaseIdealLoop* phase)
1897     : _dom(dom), _stack(0), _phase(phase) {
1898   }
1899 
1900   float to(Node* n);
1901 };
1902 
1903 // Utility class to work on predicates.
1904 class Predicates {
1905  public:
1906   static Node* skip_all_predicates(Node* node);
1907   static Node* skip_all_predicates(ParsePredicates& parse_predicates);
1908   static Node* skip_predicates_in_block(ParsePredicateSuccessProj* parse_predicate_success_proj);
1909   static IfProjNode* next_predicate_proj_in_block(IfProjNode* proj);
1910   static bool has_profiled_loop_predicates(ParsePredicates& parse_predicates);
1911 };
1912 
1913 // Class representing the Parse Predicates that are added during parsing with ParsePredicateNodes.
1914 class ParsePredicates {
1915  private:
1916   ParsePredicateSuccessProj* _loop_predicate_proj = nullptr;
1917   ParsePredicateSuccessProj* _profiled_loop_predicate_proj = nullptr;
1918   ParsePredicateSuccessProj* _loop_limit_check_predicate_proj = nullptr;
1919   // The success projection of the Parse Predicate that comes first when starting from root.
1920   ParsePredicateSuccessProj* _top_predicate_proj;
1921   ParsePredicateSuccessProj* _starting_proj;
1922 
1923   void find_parse_predicate_projections();
1924   static bool is_uct_proj(Node* node, Deoptimization::DeoptReason deopt_reason);
1925   static ParsePredicateNode* get_parse_predicate_or_null(Node* proj);
1926   bool assign_predicate_proj(ParsePredicateSuccessProj* parse_predicate_proj);
1927  public:
1928   ParsePredicates(Node* starting_proj);
1929 
1930   // Success projection of Loop Parse Predicate.
1931   ParsePredicateSuccessProj* loop_predicate_proj() {
1932     return _loop_predicate_proj;
1933   }
1934 
1935   // Success proj of Profiled Loop Parse Predicate.
1936   ParsePredicateSuccessProj* profiled_loop_predicate_proj() {
1937     return _profiled_loop_predicate_proj;
1938   }
1939 
1940   // Success proj of Loop Limit Check Parse Predicate.
1941   ParsePredicateSuccessProj* loop_limit_check_predicate_proj() {
1942     return _loop_limit_check_predicate_proj;
1943   }
1944 
1945   // Return the success projection of the Parse Predicate that comes first when starting from root.
1946   ParsePredicateSuccessProj* get_top_predicate_proj() {
1947     return _top_predicate_proj;
1948   }
1949 
1950   static bool is_success_proj(Node* node);
1951 
1952   // Are there any Parse Predicates?
1953   bool has_any() const {
1954     return _top_predicate_proj != nullptr;
1955   }
1956 
1957   static bool is_loop_limit_check_predicate_proj(Node* node) {
1958     ParsePredicateNode* parse_predicate = get_parse_predicate_or_null(node);
1959     return parse_predicate != nullptr && parse_predicate->deopt_reason() == Deoptimization::DeoptReason::Reason_loop_limit_check;
1960   }
1961 };
1962 #endif // SHARE_OPTO_LOOPNODE_HPP