1 /*
   2  * Copyright (c) 1998, 2024, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
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  24 
  25 #ifndef SHARE_OPTO_LOOPNODE_HPP
  26 #define SHARE_OPTO_LOOPNODE_HPP
  27 
  28 #include "opto/cfgnode.hpp"
  29 #include "opto/multnode.hpp"
  30 #include "opto/phaseX.hpp"
  31 #include "opto/predicates.hpp"
  32 #include "opto/subnode.hpp"
  33 #include "opto/type.hpp"
  34 #include "utilities/checkedCast.hpp"
  35 
  36 class CmpNode;
  37 class BaseCountedLoopEndNode;
  38 class CountedLoopNode;
  39 class IdealLoopTree;
  40 class LoopNode;
  41 class Node;
  42 class OuterStripMinedLoopEndNode;
  43 class PredicateBlock;
  44 class PathFrequency;
  45 class PhaseIdealLoop;
  46 class UnswitchCandidate;
  47 class UnswitchedLoopSelector;
  48 class VectorSet;
  49 class VSharedData;
  50 class Invariance;
  51 struct small_cache;
  52 
  53 //
  54 //                  I D E A L I Z E D   L O O P S
  55 //
  56 // Idealized loops are the set of loops I perform more interesting
  57 // transformations on, beyond simple hoisting.
  58 
  59 //------------------------------LoopNode---------------------------------------
  60 // Simple loop header.  Fall in path on left, loop-back path on right.
  61 class LoopNode : public RegionNode {
  62   // Size is bigger to hold the flags.  However, the flags do not change
  63   // the semantics so it does not appear in the hash & cmp functions.
  64   virtual uint size_of() const { return sizeof(*this); }
  65 protected:
  66   uint _loop_flags;
  67   // Names for flag bitfields
  68   enum { Normal=0, Pre=1, Main=2, Post=3, PreMainPostFlagsMask=3,
  69          MainHasNoPreLoop      = 1<<2,
  70          HasExactTripCount     = 1<<3,
  71          InnerLoop             = 1<<4,
  72          PartialPeelLoop       = 1<<5,
  73          PartialPeelFailed     = 1<<6,
  74          WasSlpAnalyzed        = 1<<7,
  75          PassedSlpAnalysis     = 1<<8,
  76          DoUnrollOnly          = 1<<9,
  77          VectorizedLoop        = 1<<10,
  78          HasAtomicPostLoop     = 1<<11,
  79          StripMined            = 1<<12,
  80          SubwordLoop           = 1<<13,
  81          ProfileTripFailed     = 1<<14,
  82          LoopNestInnerLoop     = 1<<15,
  83          LoopNestLongOuterLoop = 1<<16,
  84          FlatArrays            = 1<<17};
  85   char _unswitch_count;
  86   enum { _unswitch_max=3 };
  87 
  88   // Expected trip count from profile data
  89   float _profile_trip_cnt;
  90 
  91 public:
  92   // Names for edge indices
  93   enum { Self=0, EntryControl, LoopBackControl };
  94 
  95   bool is_inner_loop() const { return _loop_flags & InnerLoop; }
  96   void set_inner_loop() { _loop_flags |= InnerLoop; }
  97 
  98   bool is_vectorized_loop() const { return _loop_flags & VectorizedLoop; }
  99   bool is_partial_peel_loop() const { return _loop_flags & PartialPeelLoop; }
 100   void set_partial_peel_loop() { _loop_flags |= PartialPeelLoop; }
 101   bool partial_peel_has_failed() const { return _loop_flags & PartialPeelFailed; }
 102   bool is_strip_mined() const { return _loop_flags & StripMined; }
 103   bool is_profile_trip_failed() const { return _loop_flags & ProfileTripFailed; }
 104   bool is_subword_loop() const { return _loop_flags & SubwordLoop; }
 105   bool is_loop_nest_inner_loop() const { return _loop_flags & LoopNestInnerLoop; }
 106   bool is_loop_nest_outer_loop() const { return _loop_flags & LoopNestLongOuterLoop; }
 107   bool is_flat_arrays() const { return _loop_flags & FlatArrays; }
 108 
 109   void mark_partial_peel_failed() { _loop_flags |= PartialPeelFailed; }
 110   void mark_was_slp() { _loop_flags |= WasSlpAnalyzed; }
 111   void mark_passed_slp() { _loop_flags |= PassedSlpAnalysis; }
 112   void mark_do_unroll_only() { _loop_flags |= DoUnrollOnly; }
 113   void mark_loop_vectorized() { _loop_flags |= VectorizedLoop; }
 114   void mark_has_atomic_post_loop() { _loop_flags |= HasAtomicPostLoop; }
 115   void mark_strip_mined() { _loop_flags |= StripMined; }
 116   void clear_strip_mined() { _loop_flags &= ~StripMined; }
 117   void mark_profile_trip_failed() { _loop_flags |= ProfileTripFailed; }
 118   void mark_subword_loop() { _loop_flags |= SubwordLoop; }
 119   void mark_loop_nest_inner_loop() { _loop_flags |= LoopNestInnerLoop; }
 120   void mark_loop_nest_outer_loop() { _loop_flags |= LoopNestLongOuterLoop; }
 121   void mark_flat_arrays() { _loop_flags |= FlatArrays; }
 122 
 123   int unswitch_max() { return _unswitch_max; }
 124   int unswitch_count() { return _unswitch_count; }
 125 
 126   void set_unswitch_count(int val) {
 127     assert (val <= unswitch_max(), "too many unswitches");
 128     _unswitch_count = val;
 129   }
 130 
 131   void set_profile_trip_cnt(float ptc) { _profile_trip_cnt = ptc; }
 132   float profile_trip_cnt()             { return _profile_trip_cnt; }
 133 
 134   LoopNode(Node *entry, Node *backedge)
 135     : RegionNode(3), _loop_flags(0), _unswitch_count(0),
 136       _profile_trip_cnt(COUNT_UNKNOWN) {
 137     init_class_id(Class_Loop);
 138     init_req(EntryControl, entry);
 139     init_req(LoopBackControl, backedge);
 140   }
 141 
 142   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 143   virtual int Opcode() const;
 144   bool can_be_counted_loop(PhaseValues* phase) const {
 145     return req() == 3 && in(0) != nullptr &&
 146       in(1) != nullptr && phase->type(in(1)) != Type::TOP &&
 147       in(2) != nullptr && phase->type(in(2)) != Type::TOP;
 148   }
 149   bool is_valid_counted_loop(BasicType bt) const;
 150 #ifndef PRODUCT
 151   virtual void dump_spec(outputStream *st) const;
 152 #endif
 153 
 154   void verify_strip_mined(int expect_skeleton) const NOT_DEBUG_RETURN;
 155   virtual LoopNode* skip_strip_mined(int expect_skeleton = 1) { return this; }
 156   virtual IfTrueNode* outer_loop_tail() const { ShouldNotReachHere(); return nullptr; }
 157   virtual OuterStripMinedLoopEndNode* outer_loop_end() const { ShouldNotReachHere(); return nullptr; }
 158   virtual IfFalseNode* outer_loop_exit() const { ShouldNotReachHere(); return nullptr; }
 159   virtual SafePointNode* outer_safepoint() const { ShouldNotReachHere(); return nullptr; }
 160 };
 161 
 162 //------------------------------Counted Loops----------------------------------
 163 // Counted loops are all trip-counted loops, with exactly 1 trip-counter exit
 164 // path (and maybe some other exit paths).  The trip-counter exit is always
 165 // last in the loop.  The trip-counter have to stride by a constant;
 166 // the exit value is also loop invariant.
 167 
 168 // CountedLoopNodes and CountedLoopEndNodes come in matched pairs.  The
 169 // CountedLoopNode has the incoming loop control and the loop-back-control
 170 // which is always the IfTrue before the matching CountedLoopEndNode.  The
 171 // CountedLoopEndNode has an incoming control (possibly not the
 172 // CountedLoopNode if there is control flow in the loop), the post-increment
 173 // trip-counter value, and the limit.  The trip-counter value is always of
 174 // the form (Op old-trip-counter stride).  The old-trip-counter is produced
 175 // by a Phi connected to the CountedLoopNode.  The stride is constant.
 176 // The Op is any commutable opcode, including Add, Mul, Xor.  The
 177 // CountedLoopEndNode also takes in the loop-invariant limit value.
 178 
 179 // From a CountedLoopNode I can reach the matching CountedLoopEndNode via the
 180 // loop-back control.  From CountedLoopEndNodes I can reach CountedLoopNodes
 181 // via the old-trip-counter from the Op node.
 182 
 183 //------------------------------CountedLoopNode--------------------------------
 184 // CountedLoopNodes head simple counted loops.  CountedLoopNodes have as
 185 // inputs the incoming loop-start control and the loop-back control, so they
 186 // act like RegionNodes.  They also take in the initial trip counter, the
 187 // loop-invariant stride and the loop-invariant limit value.  CountedLoopNodes
 188 // produce a loop-body control and the trip counter value.  Since
 189 // CountedLoopNodes behave like RegionNodes I still have a standard CFG model.
 190 
 191 class BaseCountedLoopNode : public LoopNode {
 192 public:
 193   BaseCountedLoopNode(Node *entry, Node *backedge)
 194     : LoopNode(entry, backedge) {
 195   }
 196 
 197   Node *init_control() const { return in(EntryControl); }
 198   Node *back_control() const { return in(LoopBackControl); }
 199 
 200   Node* init_trip() const;
 201   Node* stride() const;
 202   bool stride_is_con() const;
 203   Node* limit() const;
 204   Node* incr() const;
 205   Node* phi() const;
 206 
 207   BaseCountedLoopEndNode* loopexit_or_null() const;
 208   BaseCountedLoopEndNode* loopexit() const;
 209 
 210   virtual BasicType bt() const = 0;
 211 
 212   jlong stride_con() const;
 213 
 214   static BaseCountedLoopNode* make(Node* entry, Node* backedge, BasicType bt);
 215 };
 216 
 217 
 218 class CountedLoopNode : public BaseCountedLoopNode {
 219   // Size is bigger to hold _main_idx.  However, _main_idx does not change
 220   // the semantics so it does not appear in the hash & cmp functions.
 221   virtual uint size_of() const { return sizeof(*this); }
 222 
 223   // For Pre- and Post-loops during debugging ONLY, this holds the index of
 224   // the Main CountedLoop.  Used to assert that we understand the graph shape.
 225   node_idx_t _main_idx;
 226 
 227   // Known trip count calculated by compute_exact_trip_count()
 228   uint  _trip_count;
 229 
 230   // Log2 of original loop bodies in unrolled loop
 231   int _unrolled_count_log2;
 232 
 233   // Node count prior to last unrolling - used to decide if
 234   // unroll,optimize,unroll,optimize,... is making progress
 235   int _node_count_before_unroll;
 236 
 237   // If slp analysis is performed we record the maximum
 238   // vector mapped unroll factor here
 239   int _slp_maximum_unroll_factor;
 240 
 241 public:
 242   CountedLoopNode(Node *entry, Node *backedge)
 243     : BaseCountedLoopNode(entry, backedge), _main_idx(0), _trip_count(max_juint),
 244       _unrolled_count_log2(0), _node_count_before_unroll(0),
 245       _slp_maximum_unroll_factor(0) {
 246     init_class_id(Class_CountedLoop);
 247     // Initialize _trip_count to the largest possible value.
 248     // Will be reset (lower) if the loop's trip count is known.
 249   }
 250 
 251   virtual int Opcode() const;
 252   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 253 
 254   CountedLoopEndNode* loopexit_or_null() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
 255   CountedLoopEndNode* loopexit() const { return (CountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
 256   int   stride_con() const;
 257 
 258   // Match increment with optional truncation
 259   static Node*
 260   match_incr_with_optional_truncation(Node* expr, Node** trunc1, Node** trunc2, const TypeInteger** trunc_type,
 261                                       BasicType bt);
 262 
 263   // A 'main' loop has a pre-loop and a post-loop.  The 'main' loop
 264   // can run short a few iterations and may start a few iterations in.
 265   // It will be RCE'd and unrolled and aligned.
 266 
 267   // A following 'post' loop will run any remaining iterations.  Used
 268   // during Range Check Elimination, the 'post' loop will do any final
 269   // iterations with full checks.  Also used by Loop Unrolling, where
 270   // the 'post' loop will do any epilog iterations needed.  Basically,
 271   // a 'post' loop can not profitably be further unrolled or RCE'd.
 272 
 273   // A preceding 'pre' loop will run at least 1 iteration (to do peeling),
 274   // it may do under-flow checks for RCE and may do alignment iterations
 275   // so the following main loop 'knows' that it is striding down cache
 276   // lines.
 277 
 278   // A 'main' loop that is ONLY unrolled or peeled, never RCE'd or
 279   // Aligned, may be missing it's pre-loop.
 280   bool is_normal_loop   () const { return (_loop_flags&PreMainPostFlagsMask) == Normal; }
 281   bool is_pre_loop      () const { return (_loop_flags&PreMainPostFlagsMask) == Pre;    }
 282   bool is_main_loop     () const { return (_loop_flags&PreMainPostFlagsMask) == Main;   }
 283   bool is_post_loop     () const { return (_loop_flags&PreMainPostFlagsMask) == Post;   }
 284   bool was_slp_analyzed () const { return (_loop_flags&WasSlpAnalyzed) == WasSlpAnalyzed; }
 285   bool has_passed_slp   () const { return (_loop_flags&PassedSlpAnalysis) == PassedSlpAnalysis; }
 286   bool is_unroll_only   () const { return (_loop_flags&DoUnrollOnly) == DoUnrollOnly; }
 287   bool is_main_no_pre_loop() const { return _loop_flags & MainHasNoPreLoop; }
 288   bool has_atomic_post_loop  () const { return (_loop_flags & HasAtomicPostLoop) == HasAtomicPostLoop; }
 289   void set_main_no_pre_loop() { _loop_flags |= MainHasNoPreLoop; }
 290 
 291   int main_idx() const { return _main_idx; }
 292 
 293 
 294   void set_pre_loop  (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Pre ; _main_idx = main->_idx; }
 295   void set_main_loop (                     ) { assert(is_normal_loop(),""); _loop_flags |= Main;                         }
 296   void set_post_loop (CountedLoopNode *main) { assert(is_normal_loop(),""); _loop_flags |= Post; _main_idx = main->_idx; }
 297   void set_normal_loop(                    ) { _loop_flags &= ~PreMainPostFlagsMask; }
 298 
 299   void set_trip_count(uint tc) { _trip_count = tc; }
 300   uint trip_count()            { return _trip_count; }
 301 
 302   bool has_exact_trip_count() const { return (_loop_flags & HasExactTripCount) != 0; }
 303   void set_exact_trip_count(uint tc) {
 304     _trip_count = tc;
 305     _loop_flags |= HasExactTripCount;
 306   }
 307   void set_nonexact_trip_count() {
 308     _loop_flags &= ~HasExactTripCount;
 309   }
 310   void set_notpassed_slp() {
 311     _loop_flags &= ~PassedSlpAnalysis;
 312   }
 313 
 314   void double_unrolled_count() { _unrolled_count_log2++; }
 315   int  unrolled_count()        { return 1 << MIN2(_unrolled_count_log2, BitsPerInt-3); }
 316 
 317   void set_node_count_before_unroll(int ct)  { _node_count_before_unroll = ct; }
 318   int  node_count_before_unroll()            { return _node_count_before_unroll; }
 319   void set_slp_max_unroll(int unroll_factor) { _slp_maximum_unroll_factor = unroll_factor; }
 320   int  slp_max_unroll() const                { return _slp_maximum_unroll_factor; }
 321 
 322   virtual LoopNode* skip_strip_mined(int expect_skeleton = 1);
 323   OuterStripMinedLoopNode* outer_loop() const;
 324   virtual IfTrueNode* outer_loop_tail() const;
 325   virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
 326   virtual IfFalseNode* outer_loop_exit() const;
 327   virtual SafePointNode* outer_safepoint() const;
 328 
 329   Node* skip_assertion_predicates_with_halt();
 330 
 331   virtual BasicType bt() const {
 332     return T_INT;
 333   }
 334 
 335   Node* is_canonical_loop_entry();
 336   CountedLoopEndNode* find_pre_loop_end();
 337 
 338 #ifndef PRODUCT
 339   virtual void dump_spec(outputStream *st) const;
 340 #endif
 341 };
 342 
 343 class LongCountedLoopNode : public BaseCountedLoopNode {
 344 public:
 345   LongCountedLoopNode(Node *entry, Node *backedge)
 346     : BaseCountedLoopNode(entry, backedge) {
 347     init_class_id(Class_LongCountedLoop);
 348   }
 349 
 350   virtual int Opcode() const;
 351 
 352   virtual BasicType bt() const {
 353     return T_LONG;
 354   }
 355 
 356   LongCountedLoopEndNode* loopexit_or_null() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit_or_null(); }
 357   LongCountedLoopEndNode* loopexit() const { return (LongCountedLoopEndNode*) BaseCountedLoopNode::loopexit(); }
 358 };
 359 
 360 
 361 //------------------------------CountedLoopEndNode-----------------------------
 362 // CountedLoopEndNodes end simple trip counted loops.  They act much like
 363 // IfNodes.
 364 
 365 class BaseCountedLoopEndNode : public IfNode {
 366 public:
 367   enum { TestControl, TestValue };
 368   BaseCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 369     : IfNode(control, test, prob, cnt) {
 370     init_class_id(Class_BaseCountedLoopEnd);
 371   }
 372 
 373   Node *cmp_node() const            { return (in(TestValue)->req() >=2) ? in(TestValue)->in(1) : nullptr; }
 374   Node* incr() const                { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
 375   Node* limit() const               { Node* tmp = cmp_node(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
 376   Node* stride() const              { Node* tmp = incr(); return (tmp && tmp->req() == 3) ? tmp->in(2) : nullptr; }
 377   Node* init_trip() const           { Node* tmp = phi(); return (tmp && tmp->req() == 3) ? tmp->in(1) : nullptr; }
 378   bool stride_is_con() const        { Node *tmp = stride(); return (tmp != nullptr && tmp->is_Con()); }
 379 
 380   PhiNode* phi() const {
 381     Node* tmp = incr();
 382     if (tmp && tmp->req() == 3) {
 383       Node* phi = tmp->in(1);
 384       if (phi->is_Phi()) {
 385         return phi->as_Phi();
 386       }
 387     }
 388     return nullptr;
 389   }
 390 
 391   BaseCountedLoopNode* loopnode() const {
 392     // The CountedLoopNode that goes with this CountedLoopEndNode may
 393     // have been optimized out by the IGVN so be cautious with the
 394     // pattern matching on the graph
 395     PhiNode* iv_phi = phi();
 396     if (iv_phi == nullptr) {
 397       return nullptr;
 398     }
 399     Node* ln = iv_phi->in(0);
 400     if (!ln->is_BaseCountedLoop() || ln->as_BaseCountedLoop()->loopexit_or_null() != this) {
 401       return nullptr;
 402     }
 403     if (ln->as_BaseCountedLoop()->bt() != bt()) {
 404       return nullptr;
 405     }
 406     return ln->as_BaseCountedLoop();
 407   }
 408 
 409   BoolTest::mask test_trip() const  { return in(TestValue)->as_Bool()->_test._test; }
 410 
 411   jlong stride_con() const;
 412   virtual BasicType bt() const = 0;
 413 
 414   static BaseCountedLoopEndNode* make(Node* control, Node* test, float prob, float cnt, BasicType bt);
 415 };
 416 
 417 class CountedLoopEndNode : public BaseCountedLoopEndNode {
 418 public:
 419 
 420   CountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 421     : BaseCountedLoopEndNode(control, test, prob, cnt) {
 422     init_class_id(Class_CountedLoopEnd);
 423   }
 424   virtual int Opcode() const;
 425 
 426   CountedLoopNode* loopnode() const {
 427     return (CountedLoopNode*) BaseCountedLoopEndNode::loopnode();
 428   }
 429 
 430   virtual BasicType bt() const {
 431     return T_INT;
 432   }
 433 
 434 #ifndef PRODUCT
 435   virtual void dump_spec(outputStream *st) const;
 436 #endif
 437 };
 438 
 439 class LongCountedLoopEndNode : public BaseCountedLoopEndNode {
 440 public:
 441   LongCountedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 442     : BaseCountedLoopEndNode(control, test, prob, cnt) {
 443     init_class_id(Class_LongCountedLoopEnd);
 444   }
 445 
 446   LongCountedLoopNode* loopnode() const {
 447     return (LongCountedLoopNode*) BaseCountedLoopEndNode::loopnode();
 448   }
 449 
 450   virtual int Opcode() const;
 451 
 452   virtual BasicType bt() const {
 453     return T_LONG;
 454   }
 455 };
 456 
 457 
 458 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit_or_null() const {
 459   Node* bctrl = back_control();
 460   if (bctrl == nullptr) return nullptr;
 461 
 462   Node* lexit = bctrl->in(0);
 463   if (!lexit->is_BaseCountedLoopEnd()) {
 464     return nullptr;
 465   }
 466   BaseCountedLoopEndNode* result = lexit->as_BaseCountedLoopEnd();
 467   if (result->bt() != bt()) {
 468     return nullptr;
 469   }
 470   return result;
 471 }
 472 
 473 inline BaseCountedLoopEndNode* BaseCountedLoopNode::loopexit() const {
 474   BaseCountedLoopEndNode* cle = loopexit_or_null();
 475   assert(cle != nullptr, "loopexit is null");
 476   return cle;
 477 }
 478 
 479 inline Node* BaseCountedLoopNode::init_trip() const {
 480   BaseCountedLoopEndNode* cle = loopexit_or_null();
 481   return cle != nullptr ? cle->init_trip() : nullptr;
 482 }
 483 inline Node* BaseCountedLoopNode::stride() const {
 484   BaseCountedLoopEndNode* cle = loopexit_or_null();
 485   return cle != nullptr ? cle->stride() : nullptr;
 486 }
 487 
 488 inline bool BaseCountedLoopNode::stride_is_con() const {
 489   BaseCountedLoopEndNode* cle = loopexit_or_null();
 490   return cle != nullptr && cle->stride_is_con();
 491 }
 492 inline Node* BaseCountedLoopNode::limit() const {
 493   BaseCountedLoopEndNode* cle = loopexit_or_null();
 494   return cle != nullptr ? cle->limit() : nullptr;
 495 }
 496 inline Node* BaseCountedLoopNode::incr() const {
 497   BaseCountedLoopEndNode* cle = loopexit_or_null();
 498   return cle != nullptr ? cle->incr() : nullptr;
 499 }
 500 inline Node* BaseCountedLoopNode::phi() const {
 501   BaseCountedLoopEndNode* cle = loopexit_or_null();
 502   return cle != nullptr ? cle->phi() : nullptr;
 503 }
 504 
 505 inline jlong BaseCountedLoopNode::stride_con() const {
 506   BaseCountedLoopEndNode* cle = loopexit_or_null();
 507   return cle != nullptr ? cle->stride_con() : 0;
 508 }
 509 
 510 
 511 //------------------------------LoopLimitNode-----------------------------
 512 // Counted Loop limit node which represents exact final iterator value:
 513 // trip_count = (limit - init_trip + stride - 1)/stride
 514 // final_value= trip_count * stride + init_trip.
 515 // Use HW instructions to calculate it when it can overflow in integer.
 516 // Note, final_value should fit into integer since counted loop has
 517 // limit check: limit <= max_int-stride.
 518 class LoopLimitNode : public Node {
 519   enum { Init=1, Limit=2, Stride=3 };
 520  public:
 521   LoopLimitNode( Compile* C, Node *init, Node *limit, Node *stride ) : Node(nullptr,init,limit,stride) {
 522     // Put it on the Macro nodes list to optimize during macro nodes expansion.
 523     init_flags(Flag_is_macro);
 524     C->add_macro_node(this);
 525   }
 526   virtual int Opcode() const;
 527   virtual const Type *bottom_type() const { return TypeInt::INT; }
 528   virtual uint ideal_reg() const { return Op_RegI; }
 529   virtual const Type* Value(PhaseGVN* phase) const;
 530   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 531   virtual Node* Identity(PhaseGVN* phase);
 532 };
 533 
 534 // Support for strip mining
 535 class OuterStripMinedLoopNode : public LoopNode {
 536 private:
 537   static void fix_sunk_stores(CountedLoopEndNode* inner_cle, LoopNode* inner_cl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
 538 
 539 public:
 540   OuterStripMinedLoopNode(Compile* C, Node *entry, Node *backedge)
 541     : LoopNode(entry, backedge) {
 542     init_class_id(Class_OuterStripMinedLoop);
 543     init_flags(Flag_is_macro);
 544     C->add_macro_node(this);
 545   }
 546 
 547   virtual int Opcode() const;
 548 
 549   virtual IfTrueNode* outer_loop_tail() const;
 550   virtual OuterStripMinedLoopEndNode* outer_loop_end() const;
 551   virtual IfFalseNode* outer_loop_exit() const;
 552   virtual SafePointNode* outer_safepoint() const;
 553   void adjust_strip_mined_loop(PhaseIterGVN* igvn);
 554 
 555   void remove_outer_loop_and_safepoint(PhaseIterGVN* igvn) const;
 556 
 557   void transform_to_counted_loop(PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
 558 
 559   static Node* register_new_node(Node* node, LoopNode* ctrl, PhaseIterGVN* igvn, PhaseIdealLoop* iloop);
 560 
 561   Node* register_control(Node* node, Node* loop, Node* idom, PhaseIterGVN* igvn,
 562                          PhaseIdealLoop* iloop);
 563 };
 564 
 565 class OuterStripMinedLoopEndNode : public IfNode {
 566 public:
 567   OuterStripMinedLoopEndNode(Node *control, Node *test, float prob, float cnt)
 568     : IfNode(control, test, prob, cnt) {
 569     init_class_id(Class_OuterStripMinedLoopEnd);
 570   }
 571 
 572   virtual int Opcode() const;
 573 
 574   virtual const Type* Value(PhaseGVN* phase) const;
 575   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
 576 
 577   bool is_expanded(PhaseGVN *phase) const;
 578 };
 579 
 580 // -----------------------------IdealLoopTree----------------------------------
 581 class IdealLoopTree : public ResourceObj {
 582 public:
 583   IdealLoopTree *_parent;       // Parent in loop tree
 584   IdealLoopTree *_next;         // Next sibling in loop tree
 585   IdealLoopTree *_child;        // First child in loop tree
 586 
 587   // The head-tail backedge defines the loop.
 588   // If a loop has multiple backedges, this is addressed during cleanup where
 589   // we peel off the multiple backedges,  merging all edges at the bottom and
 590   // ensuring that one proper backedge flow into the loop.
 591   Node *_head;                  // Head of loop
 592   Node *_tail;                  // Tail of loop
 593   inline Node *tail();          // Handle lazy update of _tail field
 594   inline Node *head();          // Handle lazy update of _head field
 595   PhaseIdealLoop* _phase;
 596   int _local_loop_unroll_limit;
 597   int _local_loop_unroll_factor;
 598 
 599   Node_List _body;              // Loop body for inner loops
 600 
 601   uint16_t _nest;               // Nesting depth
 602   uint8_t _irreducible:1,       // True if irreducible
 603           _has_call:1,          // True if has call safepoint
 604           _has_sfpt:1,          // True if has non-call safepoint
 605           _rce_candidate:1,     // True if candidate for range check elimination
 606           _has_range_checks:1,
 607           _has_range_checks_computed:1;
 608 
 609   Node_List* _safepts;          // List of safepoints in this loop
 610   Node_List* _required_safept;  // A inner loop cannot delete these safepts;
 611   bool  _allow_optimizations;   // Allow loop optimizations
 612 
 613   IdealLoopTree( PhaseIdealLoop* phase, Node *head, Node *tail )
 614     : _parent(nullptr), _next(nullptr), _child(nullptr),
 615       _head(head), _tail(tail),
 616       _phase(phase),
 617       _local_loop_unroll_limit(0), _local_loop_unroll_factor(0),
 618       _body(Compile::current()->comp_arena()),
 619       _nest(0), _irreducible(0), _has_call(0), _has_sfpt(0), _rce_candidate(0),
 620       _has_range_checks(0), _has_range_checks_computed(0),
 621       _safepts(nullptr),
 622       _required_safept(nullptr),
 623       _allow_optimizations(true)
 624   {
 625     precond(_head != nullptr);
 626     precond(_tail != nullptr);
 627   }
 628 
 629   // Is 'l' a member of 'this'?
 630   bool is_member(const IdealLoopTree *l) const; // Test for nested membership
 631 
 632   // Set loop nesting depth.  Accumulate has_call bits.
 633   int set_nest( uint depth );
 634 
 635   // Split out multiple fall-in edges from the loop header.  Move them to a
 636   // private RegionNode before the loop.  This becomes the loop landing pad.
 637   void split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt );
 638 
 639   // Split out the outermost loop from this shared header.
 640   void split_outer_loop( PhaseIdealLoop *phase );
 641 
 642   // Merge all the backedges from the shared header into a private Region.
 643   // Feed that region as the one backedge to this loop.
 644   void merge_many_backedges( PhaseIdealLoop *phase );
 645 
 646   // Split shared headers and insert loop landing pads.
 647   // Insert a LoopNode to replace the RegionNode.
 648   // Returns TRUE if loop tree is structurally changed.
 649   bool beautify_loops( PhaseIdealLoop *phase );
 650 
 651   // Perform optimization to use the loop predicates for null checks and range checks.
 652   // Applies to any loop level (not just the innermost one)
 653   bool loop_predication( PhaseIdealLoop *phase);
 654   bool can_apply_loop_predication();
 655 
 656   // Perform iteration-splitting on inner loops.  Split iterations to
 657   // avoid range checks or one-shot null checks.  Returns false if the
 658   // current round of loop opts should stop.
 659   bool iteration_split( PhaseIdealLoop *phase, Node_List &old_new );
 660 
 661   // Driver for various flavors of iteration splitting.  Returns false
 662   // if the current round of loop opts should stop.
 663   bool iteration_split_impl( PhaseIdealLoop *phase, Node_List &old_new );
 664 
 665   // Given dominators, try to find loops with calls that must always be
 666   // executed (call dominates loop tail).  These loops do not need non-call
 667   // safepoints (ncsfpt).
 668   void check_safepts(VectorSet &visited, Node_List &stack);
 669 
 670   // Allpaths backwards scan from loop tail, terminating each path at first safepoint
 671   // encountered.
 672   void allpaths_check_safepts(VectorSet &visited, Node_List &stack);
 673 
 674   // Remove safepoints from loop. Optionally keeping one.
 675   void remove_safepoints(PhaseIdealLoop* phase, bool keep_one);
 676 
 677   // Convert to counted loops where possible
 678   void counted_loop( PhaseIdealLoop *phase );
 679 
 680   // Check for Node being a loop-breaking test
 681   Node *is_loop_exit(Node *iff) const;
 682 
 683   // Remove simplistic dead code from loop body
 684   void DCE_loop_body();
 685 
 686   // Look for loop-exit tests with my 50/50 guesses from the Parsing stage.
 687   // Replace with a 1-in-10 exit guess.
 688   void adjust_loop_exit_prob( PhaseIdealLoop *phase );
 689 
 690   // Return TRUE or FALSE if the loop should never be RCE'd or aligned.
 691   // Useful for unrolling loops with NO array accesses.
 692   bool policy_peel_only( PhaseIdealLoop *phase ) const;
 693 
 694   // Return TRUE or FALSE if the loop should be unswitched -- clone
 695   // loop with an invariant test
 696   bool policy_unswitching( PhaseIdealLoop *phase ) const;
 697   bool no_unswitch_candidate() const;
 698 
 699   // Micro-benchmark spamming.  Remove empty loops.
 700   bool do_remove_empty_loop( PhaseIdealLoop *phase );
 701 
 702   // Convert one iteration loop into normal code.
 703   bool do_one_iteration_loop( PhaseIdealLoop *phase );
 704 
 705   // Return TRUE or FALSE if the loop should be peeled or not. Peel if we can
 706   // move some loop-invariant test (usually a null-check) before the loop.
 707   bool policy_peeling(PhaseIdealLoop *phase);
 708 
 709   uint estimate_peeling(PhaseIdealLoop *phase);
 710 
 711   // Return TRUE or FALSE if the loop should be maximally unrolled. Stash any
 712   // known trip count in the counted loop node.
 713   bool policy_maximally_unroll(PhaseIdealLoop *phase) const;
 714 
 715   // Return TRUE or FALSE if the loop should be unrolled or not. Apply unroll
 716   // if the loop is a counted loop and the loop body is small enough.
 717   bool policy_unroll(PhaseIdealLoop *phase);
 718 
 719   // Loop analyses to map to a maximal superword unrolling for vectorization.
 720   void policy_unroll_slp_analysis(CountedLoopNode *cl, PhaseIdealLoop *phase, int future_unroll_ct);
 721 
 722   // Return TRUE or FALSE if the loop should be range-check-eliminated.
 723   // Gather a list of IF tests that are dominated by iteration splitting;
 724   // also gather the end of the first split and the start of the 2nd split.
 725   bool policy_range_check(PhaseIdealLoop* phase, bool provisional, BasicType bt) const;
 726 
 727   // Return TRUE if "iff" is a range check.
 728   bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, Invariance& invar DEBUG_ONLY(COMMA ProjNode* predicate_proj)) const;
 729   bool is_range_check_if(IfProjNode* if_success_proj, PhaseIdealLoop* phase, BasicType bt, Node* iv, Node*& range, Node*& offset,
 730                          jlong& scale) const;
 731 
 732   // Estimate the number of nodes required when cloning a loop (body).
 733   uint est_loop_clone_sz(uint factor) const;
 734   // Estimate the number of nodes required when unrolling a loop (body).
 735   uint est_loop_unroll_sz(uint factor) const;
 736 
 737   // Compute loop trip count if possible
 738   void compute_trip_count(PhaseIdealLoop* phase);
 739 
 740   // Compute loop trip count from profile data
 741   float compute_profile_trip_cnt_helper(Node* n);
 742   void compute_profile_trip_cnt( PhaseIdealLoop *phase );
 743 
 744   // Reassociate invariant expressions.
 745   void reassociate_invariants(PhaseIdealLoop *phase);
 746   // Reassociate invariant binary expressions.
 747   Node* reassociate(Node* n1, PhaseIdealLoop *phase);
 748   // Reassociate invariant add, subtract, and compare expressions.
 749   Node* reassociate_add_sub_cmp(Node* n1, int inv1_idx, int inv2_idx, PhaseIdealLoop* phase);
 750   // Return nonzero index of invariant operand if invariant and variant
 751   // are combined with an associative binary. Helper for reassociate_invariants.
 752   int find_invariant(Node* n, PhaseIdealLoop *phase);
 753   // Return TRUE if "n" is associative.
 754   bool is_associative(Node* n, Node* base=nullptr);
 755   // Return TRUE if "n" is an associative cmp node.
 756   bool is_associative_cmp(Node* n);
 757 
 758   // Return true if n is invariant
 759   bool is_invariant(Node* n) const;
 760 
 761   // Put loop body on igvn work list
 762   void record_for_igvn();
 763 
 764   bool is_root() { return _parent == nullptr; }
 765   // A proper/reducible loop w/o any (occasional) dead back-edge.
 766   bool is_loop() { return !_irreducible && !tail()->is_top(); }
 767   bool is_counted()   { return is_loop() && _head->is_CountedLoop(); }
 768   bool is_innermost() { return is_loop() && _child == nullptr; }
 769 
 770   void remove_main_post_loops(CountedLoopNode *cl, PhaseIdealLoop *phase);
 771 
 772   bool compute_has_range_checks() const;
 773   bool range_checks_present() {
 774     if (!_has_range_checks_computed) {
 775       if (compute_has_range_checks()) {
 776         _has_range_checks = 1;
 777       }
 778       _has_range_checks_computed = 1;
 779     }
 780     return _has_range_checks;
 781   }
 782 
 783   // Return the parent's IdealLoopTree for a strip mined loop which is the outer strip mined loop.
 784   // In all other cases, return this.
 785   IdealLoopTree* skip_strip_mined() {
 786     return _head->as_Loop()->is_strip_mined() ? _parent : this;
 787   }
 788 
 789 #ifndef PRODUCT
 790   void dump_head();       // Dump loop head only
 791   void dump();            // Dump this loop recursively
 792 #endif
 793 
 794 #ifdef ASSERT
 795   GrowableArray<IdealLoopTree*> collect_sorted_children() const;
 796   bool verify_tree(IdealLoopTree* loop_verify) const;
 797 #endif
 798 
 799  private:
 800   enum { EMPTY_LOOP_SIZE = 7 }; // Number of nodes in an empty loop.
 801 
 802   // Estimate the number of nodes resulting from control and data flow merge.
 803   uint est_loop_flow_merge_sz() const;
 804 
 805   // Check if the number of residual iterations is large with unroll_cnt.
 806   // Return true if the residual iterations are more than 10% of the trip count.
 807   bool is_residual_iters_large(int unroll_cnt, CountedLoopNode *cl) const {
 808     return (unroll_cnt - 1) * (100.0 / LoopPercentProfileLimit) > cl->profile_trip_cnt();
 809   }
 810 
 811   void collect_loop_core_nodes(PhaseIdealLoop* phase, Unique_Node_List& wq) const;
 812 
 813   bool empty_loop_with_data_nodes(PhaseIdealLoop* phase) const;
 814 
 815   void enqueue_data_nodes(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq) const;
 816 
 817   bool process_safepoint(PhaseIdealLoop* phase, Unique_Node_List& empty_loop_nodes, Unique_Node_List& wq,
 818                          Node* sfpt) const;
 819 
 820   bool empty_loop_candidate(PhaseIdealLoop* phase) const;
 821 
 822   bool empty_loop_with_extra_nodes_candidate(PhaseIdealLoop* phase) const;
 823 };
 824 
 825 // -----------------------------PhaseIdealLoop---------------------------------
 826 // Computes the mapping from Nodes to IdealLoopTrees. Organizes IdealLoopTrees
 827 // into a loop tree. Drives the loop-based transformations on the ideal graph.
 828 class PhaseIdealLoop : public PhaseTransform {
 829   friend class IdealLoopTree;
 830   friend class SuperWord;
 831   friend class ShenandoahBarrierC2Support;
 832   friend class AutoNodeBudget;
 833 
 834   // Map loop membership for CFG nodes, and ctrl for non-CFG nodes.
 835   Node_List _loop_or_ctrl;
 836 
 837   // Pre-computed def-use info
 838   PhaseIterGVN &_igvn;
 839 
 840   // Head of loop tree
 841   IdealLoopTree* _ltree_root;
 842 
 843   // Array of pre-order numbers, plus post-visited bit.
 844   // ZERO for not pre-visited.  EVEN for pre-visited but not post-visited.
 845   // ODD for post-visited.  Other bits are the pre-order number.
 846   uint *_preorders;
 847   uint _max_preorder;
 848 
 849   ReallocMark _nesting; // Safety checks for arena reallocation
 850 
 851   const PhaseIdealLoop* _verify_me;
 852   bool _verify_only;
 853 
 854   // Allocate _preorders[] array
 855   void allocate_preorders() {
 856     _max_preorder = C->unique()+8;
 857     _preorders = NEW_RESOURCE_ARRAY(uint, _max_preorder);
 858     memset(_preorders, 0, sizeof(uint) * _max_preorder);
 859   }
 860 
 861   // Allocate _preorders[] array
 862   void reallocate_preorders() {
 863     _nesting.check(); // Check if a potential re-allocation in the resource arena is safe
 864     if ( _max_preorder < C->unique() ) {
 865       _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, C->unique());
 866       _max_preorder = C->unique();
 867     }
 868     memset(_preorders, 0, sizeof(uint) * _max_preorder);
 869   }
 870 
 871   // Check to grow _preorders[] array for the case when build_loop_tree_impl()
 872   // adds new nodes.
 873   void check_grow_preorders( ) {
 874     _nesting.check(); // Check if a potential re-allocation in the resource arena is safe
 875     if ( _max_preorder < C->unique() ) {
 876       uint newsize = _max_preorder<<1;  // double size of array
 877       _preorders = REALLOC_RESOURCE_ARRAY(uint, _preorders, _max_preorder, newsize);
 878       memset(&_preorders[_max_preorder],0,sizeof(uint)*(newsize-_max_preorder));
 879       _max_preorder = newsize;
 880     }
 881   }
 882   // Check for pre-visited.  Zero for NOT visited; non-zero for visited.
 883   int is_visited( Node *n ) const { return _preorders[n->_idx]; }
 884   // Pre-order numbers are written to the Nodes array as low-bit-set values.
 885   void set_preorder_visited( Node *n, int pre_order ) {
 886     assert( !is_visited( n ), "already set" );
 887     _preorders[n->_idx] = (pre_order<<1);
 888   };
 889   // Return pre-order number.
 890   int get_preorder( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]>>1; }
 891 
 892   // Check for being post-visited.
 893   // Should be previsited already (checked with assert(is_visited(n))).
 894   int is_postvisited( Node *n ) const { assert( is_visited(n), "" ); return _preorders[n->_idx]&1; }
 895 
 896   // Mark as post visited
 897   void set_postvisited( Node *n ) { assert( !is_postvisited( n ), "" ); _preorders[n->_idx] |= 1; }
 898 
 899 public:
 900   // Set/get control node out.  Set lower bit to distinguish from IdealLoopTree
 901   // Returns true if "n" is a data node, false if it's a control node.
 902   bool has_ctrl(const Node* n) const { return ((intptr_t)_loop_or_ctrl[n->_idx]) & 1; }
 903 
 904 private:
 905   // clear out dead code after build_loop_late
 906   Node_List _deadlist;
 907   Node_List _zero_trip_guard_opaque_nodes;
 908 
 909   // Support for faster execution of get_late_ctrl()/dom_lca()
 910   // when a node has many uses and dominator depth is deep.
 911   GrowableArray<jlong> _dom_lca_tags;
 912   uint _dom_lca_tags_round;
 913   void   init_dom_lca_tags();
 914 
 915   // Helper for debugging bad dominance relationships
 916   bool verify_dominance(Node* n, Node* use, Node* LCA, Node* early);
 917 
 918   Node* compute_lca_of_uses(Node* n, Node* early, bool verify = false);
 919 
 920   // Inline wrapper for frequent cases:
 921   // 1) only one use
 922   // 2) a use is the same as the current LCA passed as 'n1'
 923   Node *dom_lca_for_get_late_ctrl( Node *lca, Node *n, Node *tag ) {
 924     assert( n->is_CFG(), "" );
 925     // Fast-path null lca
 926     if( lca != nullptr && lca != n ) {
 927       assert( lca->is_CFG(), "" );
 928       // find LCA of all uses
 929       n = dom_lca_for_get_late_ctrl_internal( lca, n, tag );
 930     }
 931     return find_non_split_ctrl(n);
 932   }
 933   Node *dom_lca_for_get_late_ctrl_internal( Node *lca, Node *n, Node *tag );
 934 
 935   // Helper function for directing control inputs away from CFG split points.
 936   Node *find_non_split_ctrl( Node *ctrl ) const {
 937     if (ctrl != nullptr) {
 938       if (ctrl->is_MultiBranch()) {
 939         ctrl = ctrl->in(0);
 940       }
 941       assert(ctrl->is_CFG(), "CFG");
 942     }
 943     return ctrl;
 944   }
 945 
 946 #ifdef ASSERT
 947   void ensure_zero_trip_guard_proj(Node* node, bool is_main_loop);
 948 #endif
 949   void copy_assertion_predicates_to_main_loop_helper(const PredicateBlock* predicate_block, Node* init, Node* stride,
 950                                                      IdealLoopTree* outer_loop, LoopNode* outer_main_head,
 951                                                      uint dd_main_head, uint idx_before_pre_post,
 952                                                      uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
 953                                                      Node* zero_trip_guard_proj_post, const Node_List &old_new);
 954   void copy_assertion_predicates_to_main_loop(CountedLoopNode* pre_head, Node* init, Node* stride, IdealLoopTree* outer_loop,
 955                                               LoopNode* outer_main_head, uint dd_main_head, uint idx_before_pre_post,
 956                                               uint idx_after_post_before_pre, Node* zero_trip_guard_proj_main,
 957                                               Node* zero_trip_guard_proj_post, const Node_List& old_new);
 958   Node* clone_template_assertion_predicate(IfNode* iff, Node* new_init, Node* predicate, Node* uncommon_proj, Node* control,
 959                                            IdealLoopTree* outer_loop, Node* new_control);
 960   IfTrueNode* create_initialized_assertion_predicate(IfNode* template_assertion_predicate, Node* new_init,
 961                                                      Node* new_stride, Node* control);
 962   static void count_opaque_loop_nodes(Node* n, uint& init, uint& stride);
 963   static bool assertion_predicate_has_loop_opaque_node(IfNode* iff);
 964   static void get_assertion_predicates(Node* predicate, Unique_Node_List& list, bool get_opaque = false);
 965   void update_main_loop_assertion_predicates(Node* ctrl, CountedLoopNode* loop_head, Node* init, int stride_con);
 966   void copy_assertion_predicates_to_post_loop(LoopNode* main_loop_head, CountedLoopNode* post_loop_head,
 967                                               Node* stride);
 968   void initialize_assertion_predicates_for_peeled_loop(const PredicateBlock* predicate_block, LoopNode* outer_loop_head,
 969                                                        int dd_outer_loop_head, Node* init, Node* stride,
 970                                                        IdealLoopTree* outer_loop, uint idx_before_clone,
 971                                                        const Node_List& old_new);
 972   void insert_loop_limit_check_predicate(ParsePredicateSuccessProj* loop_limit_check_parse_proj, Node* cmp_limit,
 973                                          Node* bol);
 974   void log_loop_tree();
 975 
 976 public:
 977 
 978   PhaseIterGVN &igvn() const { return _igvn; }
 979 
 980   bool has_node(const Node* n) const {
 981     guarantee(n != nullptr, "No Node.");
 982     return _loop_or_ctrl[n->_idx] != nullptr;
 983   }
 984   // check if transform created new nodes that need _ctrl recorded
 985   Node *get_late_ctrl( Node *n, Node *early );
 986   Node *get_early_ctrl( Node *n );
 987   Node *get_early_ctrl_for_expensive(Node *n, Node* earliest);
 988   void set_early_ctrl(Node* n, bool update_body);
 989   void set_subtree_ctrl(Node* n, bool update_body);
 990   void set_ctrl( Node *n, Node *ctrl ) {
 991     assert( !has_node(n) || has_ctrl(n), "" );
 992     assert( ctrl->in(0), "cannot set dead control node" );
 993     assert( ctrl == find_non_split_ctrl(ctrl), "must set legal crtl" );
 994     _loop_or_ctrl.map(n->_idx, (Node*)((intptr_t)ctrl + 1));
 995   }
 996   // Set control and update loop membership
 997   void set_ctrl_and_loop(Node* n, Node* ctrl) {
 998     IdealLoopTree* old_loop = get_loop(get_ctrl(n));
 999     IdealLoopTree* new_loop = get_loop(ctrl);
1000     if (old_loop != new_loop) {
1001       if (old_loop->_child == nullptr) old_loop->_body.yank(n);
1002       if (new_loop->_child == nullptr) new_loop->_body.push(n);
1003     }
1004     set_ctrl(n, ctrl);
1005   }
1006   // Control nodes can be replaced or subsumed.  During this pass they
1007   // get their replacement Node in slot 1.  Instead of updating the block
1008   // location of all Nodes in the subsumed block, we lazily do it.  As we
1009   // pull such a subsumed block out of the array, we write back the final
1010   // correct block.
1011   Node* get_ctrl(const Node* i) {
1012     assert(has_node(i), "");
1013     Node *n = get_ctrl_no_update(i);
1014     _loop_or_ctrl.map(i->_idx, (Node*)((intptr_t)n + 1));
1015     assert(has_node(i) && has_ctrl(i), "");
1016     assert(n == find_non_split_ctrl(n), "must return legal ctrl" );
1017     return n;
1018   }
1019 
1020   bool is_dominator(Node* dominator, Node* n);
1021   bool is_strict_dominator(Node* dominator, Node* n);
1022 
1023   // return get_ctrl for a data node and self(n) for a CFG node
1024   Node* ctrl_or_self(Node* n) {
1025     if (has_ctrl(n))
1026       return get_ctrl(n);
1027     else {
1028       assert (n->is_CFG(), "must be a CFG node");
1029       return n;
1030     }
1031   }
1032 
1033   Node* get_ctrl_no_update_helper(const Node* i) const {
1034     assert(has_ctrl(i), "should be control, not loop");
1035     return (Node*)(((intptr_t)_loop_or_ctrl[i->_idx]) & ~1);
1036   }
1037 
1038   Node* get_ctrl_no_update(const Node* i) const {
1039     assert( has_ctrl(i), "" );
1040     Node *n = get_ctrl_no_update_helper(i);
1041     if (!n->in(0)) {
1042       // Skip dead CFG nodes
1043       do {
1044         n = get_ctrl_no_update_helper(n);
1045       } while (!n->in(0));
1046       n = find_non_split_ctrl(n);
1047     }
1048     return n;
1049   }
1050 
1051   // Check for loop being set
1052   // "n" must be a control node. Returns true if "n" is known to be in a loop.
1053   bool has_loop( Node *n ) const {
1054     assert(!has_node(n) || !has_ctrl(n), "");
1055     return has_node(n);
1056   }
1057   // Set loop
1058   void set_loop( Node *n, IdealLoopTree *loop ) {
1059     _loop_or_ctrl.map(n->_idx, (Node*)loop);
1060   }
1061   // Lazy-dazy update of 'get_ctrl' and 'idom_at' mechanisms.  Replace
1062   // the 'old_node' with 'new_node'.  Kill old-node.  Add a reference
1063   // from old_node to new_node to support the lazy update.  Reference
1064   // replaces loop reference, since that is not needed for dead node.
1065   void lazy_update(Node *old_node, Node *new_node) {
1066     assert(old_node != new_node, "no cycles please");
1067     // Re-use the side array slot for this node to provide the
1068     // forwarding pointer.
1069     _loop_or_ctrl.map(old_node->_idx, (Node*)((intptr_t)new_node + 1));
1070   }
1071   void lazy_replace(Node *old_node, Node *new_node) {
1072     _igvn.replace_node(old_node, new_node);
1073     lazy_update(old_node, new_node);
1074   }
1075 
1076 private:
1077 
1078   // Place 'n' in some loop nest, where 'n' is a CFG node
1079   void build_loop_tree();
1080   int build_loop_tree_impl(Node* n, int pre_order);
1081   // Insert loop into the existing loop tree.  'innermost' is a leaf of the
1082   // loop tree, not the root.
1083   IdealLoopTree *sort( IdealLoopTree *loop, IdealLoopTree *innermost );
1084 
1085 #ifdef ASSERT
1086   // verify that regions in irreducible loops are marked is_in_irreducible_loop
1087   void verify_regions_in_irreducible_loops();
1088   bool is_in_irreducible_loop(RegionNode* region);
1089 #endif
1090 
1091   // Place Data nodes in some loop nest
1092   void build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1093   void build_loop_late ( VectorSet &visited, Node_List &worklist, Node_Stack &nstack );
1094   void build_loop_late_post_work(Node* n, bool pinned);
1095   void build_loop_late_post(Node* n);
1096   void verify_strip_mined_scheduling(Node *n, Node* least);
1097 
1098   // Array of immediate dominance info for each CFG node indexed by node idx
1099 private:
1100   uint _idom_size;
1101   Node **_idom;                  // Array of immediate dominators
1102   uint *_dom_depth;              // Used for fast LCA test
1103   GrowableArray<uint>* _dom_stk; // For recomputation of dom depth
1104   LoopOptsMode _mode;
1105 
1106   // build the loop tree and perform any requested optimizations
1107   void build_and_optimize();
1108 
1109   // Dominators for the sea of nodes
1110   void Dominators();
1111 
1112   // Compute the Ideal Node to Loop mapping
1113   PhaseIdealLoop(PhaseIterGVN& igvn, LoopOptsMode mode) :
1114     PhaseTransform(Ideal_Loop),
1115     _loop_or_ctrl(igvn.C->comp_arena()),
1116     _igvn(igvn),
1117     _verify_me(nullptr),
1118     _verify_only(false),
1119     _mode(mode),
1120     _nodes_required(UINT_MAX) {
1121     assert(mode != LoopOptsVerify, "wrong constructor to verify IdealLoop");
1122     build_and_optimize();
1123   }
1124 
1125 #ifndef PRODUCT
1126   // Verify that verify_me made the same decisions as a fresh run
1127   // or only verify that the graph is valid if verify_me is null.
1128   PhaseIdealLoop(PhaseIterGVN& igvn, const PhaseIdealLoop* verify_me = nullptr) :
1129     PhaseTransform(Ideal_Loop),
1130     _loop_or_ctrl(igvn.C->comp_arena()),
1131     _igvn(igvn),
1132     _verify_me(verify_me),
1133     _verify_only(verify_me == nullptr),
1134     _mode(LoopOptsVerify),
1135     _nodes_required(UINT_MAX) {
1136     DEBUG_ONLY(C->set_phase_verify_ideal_loop();)
1137     build_and_optimize();
1138     DEBUG_ONLY(C->reset_phase_verify_ideal_loop();)
1139   }
1140 #endif
1141 
1142   Node* insert_convert_node_if_needed(BasicType target, Node* input);
1143 
1144 public:
1145   Node* idom_no_update(Node* d) const {
1146     return idom_no_update(d->_idx);
1147   }
1148 
1149   Node* idom_no_update(uint didx) const {
1150     assert(didx < _idom_size, "oob");
1151     Node* n = _idom[didx];
1152     assert(n != nullptr,"Bad immediate dominator info.");
1153     while (n->in(0) == nullptr) { // Skip dead CFG nodes
1154       n = (Node*)(((intptr_t)_loop_or_ctrl[n->_idx]) & ~1);
1155       assert(n != nullptr,"Bad immediate dominator info.");
1156     }
1157     return n;
1158   }
1159 
1160   Node *idom(Node* d) const {
1161     return idom(d->_idx);
1162   }
1163 
1164   Node *idom(uint didx) const {
1165     Node *n = idom_no_update(didx);
1166     _idom[didx] = n; // Lazily remove dead CFG nodes from table.
1167     return n;
1168   }
1169 
1170   uint dom_depth(Node* d) const {
1171     guarantee(d != nullptr, "Null dominator info.");
1172     guarantee(d->_idx < _idom_size, "");
1173     return _dom_depth[d->_idx];
1174   }
1175   void set_idom(Node* d, Node* n, uint dom_depth);
1176   // Locally compute IDOM using dom_lca call
1177   Node *compute_idom( Node *region ) const;
1178   // Recompute dom_depth
1179   void recompute_dom_depth();
1180 
1181   // Is safept not required by an outer loop?
1182   bool is_deleteable_safept(Node* sfpt);
1183 
1184   // Replace parallel induction variable (parallel to trip counter)
1185   void replace_parallel_iv(IdealLoopTree *loop);
1186 
1187   Node *dom_lca( Node *n1, Node *n2 ) const {
1188     return find_non_split_ctrl(dom_lca_internal(n1, n2));
1189   }
1190   Node *dom_lca_internal( Node *n1, Node *n2 ) const;
1191 
1192   Node* dominated_node(Node* c1, Node* c2) {
1193     assert(is_dominator(c1, c2) || is_dominator(c2, c1), "nodes must be related");
1194     return is_dominator(c1, c2) ? c2 : c1;
1195   }
1196 
1197   // Return control node that's dominated by the 2 others
1198   Node* dominated_node(Node* c1, Node* c2, Node* c3) {
1199     return dominated_node(c1, dominated_node(c2, c3));
1200   }
1201 
1202   // Build and verify the loop tree without modifying the graph.  This
1203   // is useful to verify that all inputs properly dominate their uses.
1204   static void verify(PhaseIterGVN& igvn) {
1205 #ifdef ASSERT
1206     ResourceMark rm;
1207     Compile::TracePhase tp("idealLoopVerify", &timers[_t_idealLoopVerify]);
1208     PhaseIdealLoop v(igvn);
1209 #endif
1210   }
1211 
1212   // Recommended way to use PhaseIdealLoop.
1213   // Run PhaseIdealLoop in some mode and allocates a local scope for memory allocations.
1214   static void optimize(PhaseIterGVN &igvn, LoopOptsMode mode) {
1215     ResourceMark rm;
1216     PhaseIdealLoop v(igvn, mode);
1217 
1218     Compile* C = Compile::current();
1219     if (!C->failing()) {
1220       // Cleanup any modified bits
1221       igvn.optimize();
1222       if (C->failing()) { return; }
1223       v.log_loop_tree();
1224     }
1225   }
1226 
1227   // True if the method has at least 1 irreducible loop
1228   bool _has_irreducible_loops;
1229 
1230   // Per-Node transform
1231   virtual Node* transform(Node* n) { return nullptr; }
1232 
1233   Node* loop_exit_control(Node* x, IdealLoopTree* loop);
1234   Node* loop_exit_test(Node* back_control, IdealLoopTree* loop, Node*& incr, Node*& limit, BoolTest::mask& bt, float& cl_prob);
1235   Node* loop_iv_incr(Node* incr, Node* x, IdealLoopTree* loop, Node*& phi_incr);
1236   Node* loop_iv_stride(Node* incr, IdealLoopTree* loop, Node*& xphi);
1237   PhiNode* loop_iv_phi(Node* xphi, Node* phi_incr, Node* x, IdealLoopTree* loop);
1238 
1239   bool is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_bt);
1240 
1241   Node* loop_nest_replace_iv(Node* iv_to_replace, Node* inner_iv, Node* outer_phi, Node* inner_head, BasicType bt);
1242   bool create_loop_nest(IdealLoopTree* loop, Node_List &old_new);
1243 #ifdef ASSERT
1244   bool convert_to_long_loop(Node* cmp, Node* phi, IdealLoopTree* loop);
1245 #endif
1246   void add_parse_predicate(Deoptimization::DeoptReason reason, Node* inner_head, IdealLoopTree* loop, SafePointNode* sfpt);
1247   SafePointNode* find_safepoint(Node* back_control, Node* x, IdealLoopTree* loop);
1248   IdealLoopTree* insert_outer_loop(IdealLoopTree* loop, LoopNode* outer_l, Node* outer_ift);
1249   IdealLoopTree* create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
1250                                                IdealLoopTree* loop, float cl_prob, float le_fcnt,
1251                                                Node*& entry_control, Node*& iffalse);
1252 
1253   Node* exact_limit( IdealLoopTree *loop );
1254 
1255   // Return a post-walked LoopNode
1256   IdealLoopTree *get_loop( Node *n ) const {
1257     // Dead nodes have no loop, so return the top level loop instead
1258     if (!has_node(n))  return _ltree_root;
1259     assert(!has_ctrl(n), "");
1260     return (IdealLoopTree*)_loop_or_ctrl[n->_idx];
1261   }
1262 
1263   IdealLoopTree* ltree_root() const { return _ltree_root; }
1264 
1265   // Is 'n' a (nested) member of 'loop'?
1266   int is_member( const IdealLoopTree *loop, Node *n ) const {
1267     return loop->is_member(get_loop(n)); }
1268 
1269   // This is the basic building block of the loop optimizations.  It clones an
1270   // entire loop body.  It makes an old_new loop body mapping; with this
1271   // mapping you can find the new-loop equivalent to an old-loop node.  All
1272   // new-loop nodes are exactly equal to their old-loop counterparts, all
1273   // edges are the same.  All exits from the old-loop now have a RegionNode
1274   // that merges the equivalent new-loop path.  This is true even for the
1275   // normal "loop-exit" condition.  All uses of loop-invariant old-loop values
1276   // now come from (one or more) Phis that merge their new-loop equivalents.
1277   // Parameter side_by_side_idom:
1278   //   When side_by_size_idom is null, the dominator tree is constructed for
1279   //      the clone loop to dominate the original.  Used in construction of
1280   //      pre-main-post loop sequence.
1281   //   When nonnull, the clone and original are side-by-side, both are
1282   //      dominated by the passed in side_by_side_idom node.  Used in
1283   //      construction of unswitched loops.
1284   enum CloneLoopMode {
1285     IgnoreStripMined = 0,        // Only clone inner strip mined loop
1286     CloneIncludesStripMined = 1, // clone both inner and outer strip mined loops
1287     ControlAroundStripMined = 2  // Only clone inner strip mined loop,
1288                                  // result control flow branches
1289                                  // either to inner clone or outer
1290                                  // strip mined loop.
1291   };
1292   void clone_loop( IdealLoopTree *loop, Node_List &old_new, int dom_depth,
1293                   CloneLoopMode mode, Node* side_by_side_idom = nullptr);
1294   void clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1295                                    IdealLoopTree* loop, IdealLoopTree* companion_loop,
1296                                    Node_List*& split_if_set, Node_List*& split_bool_set,
1297                                    Node_List*& split_cex_set, Node_List& worklist,
1298                                    uint new_counter, CloneLoopMode mode);
1299   void clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1300                         IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1301                         Node_List& extra_data_nodes);
1302 
1303   // If we got the effect of peeling, either by actually peeling or by
1304   // making a pre-loop which must execute at least once, we can remove
1305   // all loop-invariant dominated tests in the main body.
1306   void peeled_dom_test_elim( IdealLoopTree *loop, Node_List &old_new );
1307 
1308   // Generate code to do a loop peel for the given loop (and body).
1309   // old_new is a temp array.
1310   void do_peeling( IdealLoopTree *loop, Node_List &old_new );
1311 
1312   // Add pre and post loops around the given loop.  These loops are used
1313   // during RCE, unrolling and aligning loops.
1314   void insert_pre_post_loops( IdealLoopTree *loop, Node_List &old_new, bool peel_only );
1315 
1316   // Add post loop after the given loop.
1317   Node *insert_post_loop(IdealLoopTree* loop, Node_List& old_new,
1318                          CountedLoopNode* main_head, CountedLoopEndNode* main_end,
1319                          Node*& incr, Node* limit, CountedLoopNode*& post_head);
1320 
1321   // Add a vector post loop between a vector main loop and the current post loop
1322   void insert_vector_post_loop(IdealLoopTree *loop, Node_List &old_new);
1323   // If Node n lives in the back_ctrl block, we clone a private version of n
1324   // in preheader_ctrl block and return that, otherwise return n.
1325   Node *clone_up_backedge_goo( Node *back_ctrl, Node *preheader_ctrl, Node *n, VectorSet &visited, Node_Stack &clones );
1326 
1327   // Take steps to maximally unroll the loop.  Peel any odd iterations, then
1328   // unroll to do double iterations.  The next round of major loop transforms
1329   // will repeat till the doubled loop body does all remaining iterations in 1
1330   // pass.
1331   void do_maximally_unroll( IdealLoopTree *loop, Node_List &old_new );
1332 
1333   // Unroll the loop body one step - make each trip do 2 iterations.
1334   void do_unroll( IdealLoopTree *loop, Node_List &old_new, bool adjust_min_trip );
1335 
1336   // Return true if exp is a constant times an induction var
1337   bool is_scaled_iv(Node* exp, Node* iv, BasicType bt, jlong* p_scale, bool* p_short_scale, int depth = 0);
1338 
1339   bool is_iv(Node* exp, Node* iv, BasicType bt);
1340 
1341   // Return true if exp is a scaled induction var plus (or minus) constant
1342   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);
1343   bool is_scaled_iv_plus_offset(Node* exp, Node* iv, int* p_scale, Node** p_offset) {
1344     jlong long_scale;
1345     if (is_scaled_iv_plus_offset(exp, iv, T_INT, &long_scale, p_offset)) {
1346       int int_scale = checked_cast<int>(long_scale);
1347       if (p_scale != nullptr) {
1348         *p_scale = int_scale;
1349       }
1350       return true;
1351     }
1352     return false;
1353   }
1354   // Helper for finding more complex matches to is_scaled_iv_plus_offset.
1355   bool is_scaled_iv_plus_extra_offset(Node* exp1, Node* offset2, Node* iv,
1356                                       BasicType bt,
1357                                       jlong* p_scale, Node** p_offset,
1358                                       bool* p_short_scale, int depth);
1359 
1360   // Create a new if above the uncommon_trap_if_pattern for the predicate to be promoted
1361   IfTrueNode* create_new_if_for_predicate(
1362       ParsePredicateSuccessProj* parse_predicate_proj, Node* new_entry, Deoptimization::DeoptReason reason, int opcode,
1363       bool rewire_uncommon_proj_phi_inputs = false
1364       NOT_PRODUCT (COMMA AssertionPredicateType assertion_predicate_type = AssertionPredicateType::None));
1365 
1366  private:
1367   // Helper functions for create_new_if_for_predicate()
1368   void set_ctrl_of_nodes_with_same_ctrl(Node* start_node, ProjNode* old_uncommon_proj, Node* new_uncommon_proj);
1369   Unique_Node_List find_nodes_with_same_ctrl(Node* node, const ProjNode* ctrl);
1370   Node* clone_nodes_with_same_ctrl(Node* start_node, ProjNode* old_uncommon_proj, Node* new_uncommon_proj);
1371   void fix_cloned_data_node_controls(const ProjNode* orig, Node* new_uncommon_proj,
1372                                      const OrigToNewHashtable& orig_to_clone);
1373   bool has_dominating_loop_limit_check(Node* init_trip, Node* limit, jlong stride_con, BasicType iv_bt,
1374                                        Node* loop_entry);
1375 
1376  public:
1377   void register_control(Node* n, IdealLoopTree *loop, Node* pred, bool update_body = true);
1378 
1379   void replace_loop_entry(LoopNode* loop_head, Node* new_entry) {
1380     _igvn.replace_input_of(loop_head, LoopNode::EntryControl, new_entry);
1381     set_idom(loop_head, new_entry, dom_depth(new_entry));
1382   }
1383 
1384   // Construct a range check for a predicate if
1385   BoolNode* rc_predicate(Node* ctrl, int scale, Node* offset, Node* init, Node* limit,
1386                          jint stride, Node* range, bool upper, bool& overflow);
1387 
1388   // Implementation of the loop predication to promote checks outside the loop
1389   bool loop_predication_impl(IdealLoopTree *loop);
1390 
1391  private:
1392   bool loop_predication_impl_helper(IdealLoopTree* loop, IfProjNode* if_success_proj,
1393                                     ParsePredicateSuccessProj* parse_predicate_proj, CountedLoopNode* cl, ConNode* zero,
1394                                     Invariance& invar, Deoptimization::DeoptReason deopt_reason);
1395   bool can_create_loop_predicates(const PredicateBlock* profiled_loop_predicate_block) const;
1396   bool loop_predication_should_follow_branches(IdealLoopTree* loop, float& loop_trip_cnt);
1397   void loop_predication_follow_branches(Node *c, IdealLoopTree *loop, float loop_trip_cnt,
1398                                         PathFrequency& pf, Node_Stack& stack, VectorSet& seen,
1399                                         Node_List& if_proj_list);
1400   IfTrueNode* create_template_assertion_predicate(int if_opcode, CountedLoopNode* loop_head,
1401                                                   ParsePredicateSuccessProj* parse_predicate_proj,
1402                                                   IfProjNode* new_control, int scale, Node* offset,
1403                                                   Node* range, Deoptimization::DeoptReason deopt_reason);
1404   void eliminate_hoisted_range_check(IfTrueNode* hoisted_check_proj, IfTrueNode* template_assertion_predicate_proj);
1405 
1406   // Helper function to collect predicate for eliminating the useless ones
1407   void eliminate_useless_predicates();
1408 
1409   void eliminate_useless_parse_predicates();
1410   void mark_all_parse_predicates_useless() const;
1411   void mark_loop_associated_parse_predicates_useful();
1412   static void mark_useful_parse_predicates_for_loop(IdealLoopTree* loop);
1413   void add_useless_parse_predicates_to_igvn_worklist();
1414 
1415   void eliminate_useless_template_assertion_predicates();
1416   void collect_useful_template_assertion_predicates(Unique_Node_List& useful_predicates);
1417   static void collect_useful_template_assertion_predicates_for_loop(IdealLoopTree* loop, Unique_Node_List& useful_predicates);
1418   void eliminate_useless_template_assertion_predicates(Unique_Node_List& useful_predicates);
1419 
1420   void eliminate_useless_zero_trip_guard();
1421 
1422  public:
1423   // Change the control input of expensive nodes to allow commoning by
1424   // IGVN when it is guaranteed to not result in a more frequent
1425   // execution of the expensive node. Return true if progress.
1426   bool process_expensive_nodes();
1427 
1428   // Check whether node has become unreachable
1429   bool is_node_unreachable(Node *n) const {
1430     return !has_node(n) || n->is_unreachable(_igvn);
1431   }
1432 
1433   // Eliminate range-checks and other trip-counter vs loop-invariant tests.
1434   void do_range_check(IdealLoopTree *loop, Node_List &old_new);
1435 
1436   // Clone loop with an invariant test (that does not exit) and
1437   // insert a clone of the test that selects which version to
1438   // execute.
1439   void do_unswitching(IdealLoopTree* loop, Node_List& old_new);
1440 
1441   IfNode* find_unswitch_candidates(const IdealLoopTree* loop, Node_List& flat_array_checks) const;
1442   IfNode* find_unswitch_candidate_from_idoms(const IdealLoopTree* loop) const;
1443 
1444  private:
1445   static bool has_control_dependencies_from_predicates(LoopNode* head);
1446   static void revert_to_normal_loop(const LoopNode* loop_head);
1447 
1448   void hoist_invariant_check_casts(const IdealLoopTree* loop, const Node_List& old_new,
1449                                    const UnswitchCandidate& unswitch_candidate, const IfNode* loop_selector);
1450   void add_unswitched_loop_version_bodies_to_igvn(IdealLoopTree* loop, const Node_List& old_new);
1451   static void increment_unswitch_counts(LoopNode* original_head, LoopNode* new_head);
1452   void remove_unswitch_candidate_from_loops(const Node_List& old_new, const UnswitchedLoopSelector& unswitched_loop_selector);
1453 #ifndef PRODUCT
1454   static void trace_loop_unswitching_count(IdealLoopTree* loop, LoopNode* original_head);
1455   static void trace_loop_unswitching_impossible(const LoopNode* original_head);
1456   static void trace_loop_unswitching_result(const UnswitchedLoopSelector& unswitched_loop_selector,
1457                                             const UnswitchCandidate& unswitch_candidate,
1458                                             const LoopNode* original_head, const LoopNode* new_head);
1459 #endif
1460 
1461  public:
1462 
1463   // Range Check Elimination uses this function!
1464   // Constrain the main loop iterations so the affine function:
1465   //    low_limit <= scale_con * I + offset  <  upper_limit
1466   // always holds true.  That is, either increase the number of iterations in
1467   // the pre-loop or the post-loop until the condition holds true in the main
1468   // loop.  Scale_con, offset and limit are all loop invariant.
1469   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);
1470   // Helper function for add_constraint().
1471   Node* adjust_limit(bool reduce, Node* scale, Node* offset, Node* rc_limit, Node* old_limit, Node* pre_ctrl, bool round);
1472 
1473   // Partially peel loop up through last_peel node.
1474   bool partial_peel( IdealLoopTree *loop, Node_List &old_new );
1475   bool duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new);
1476 
1477   // AutoVectorize the loop: replace scalar ops with vector ops.
1478   enum AutoVectorizeStatus {
1479     Impossible,      // This loop has the wrong shape to even try vectorization.
1480     Success,         // We just successfully vectorized the loop.
1481     TriedAndFailed,  // We tried to vectorize, but failed.
1482   };
1483   AutoVectorizeStatus auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared);
1484 
1485   // Move an unordered Reduction out of loop if possible
1486   void move_unordered_reduction_out_of_loop(IdealLoopTree* loop);
1487 
1488   // Create a scheduled list of nodes control dependent on ctrl set.
1489   void scheduled_nodelist( IdealLoopTree *loop, VectorSet& ctrl, Node_List &sched );
1490   // Has a use in the vector set
1491   bool has_use_in_set( Node* n, VectorSet& vset );
1492   // Has use internal to the vector set (ie. not in a phi at the loop head)
1493   bool has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop );
1494   // clone "n" for uses that are outside of loop
1495   int  clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist );
1496   // clone "n" for special uses that are in the not_peeled region
1497   void clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
1498                                           VectorSet& not_peel, Node_List& sink_list, Node_List& worklist );
1499   // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
1500   void insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp );
1501 #ifdef ASSERT
1502   // Validate the loop partition sets: peel and not_peel
1503   bool is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list, VectorSet& not_peel );
1504   // Ensure that uses outside of loop are of the right form
1505   bool is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
1506                                  uint orig_exit_idx, uint clone_exit_idx);
1507   bool is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx);
1508 #endif
1509 
1510   // Returns nonzero constant stride if-node is a possible iv test (otherwise returns zero.)
1511   int stride_of_possible_iv( Node* iff );
1512   bool is_possible_iv_test( Node* iff ) { return stride_of_possible_iv(iff) != 0; }
1513   // Return the (unique) control output node that's in the loop (if it exists.)
1514   Node* stay_in_loop( Node* n, IdealLoopTree *loop);
1515   // Insert a signed compare loop exit cloned from an unsigned compare.
1516   IfNode* insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop);
1517   void remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop);
1518   // Utility to register node "n" with PhaseIdealLoop
1519   void register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth);
1520   // Utility to create an if-projection
1521   ProjNode* proj_clone(ProjNode* p, IfNode* iff);
1522   // Force the iff control output to be the live_proj
1523   Node* short_circuit_if(IfNode* iff, ProjNode* live_proj);
1524   // Insert a region before an if projection
1525   RegionNode* insert_region_before_proj(ProjNode* proj);
1526   // Insert a new if before an if projection
1527   ProjNode* insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj);
1528 
1529   // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1530   // "Nearly" because all Nodes have been cloned from the original in the loop,
1531   // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1532   // through the Phi recursively, and return a Bool.
1533   Node* clone_iff(PhiNode* phi);
1534   CmpNode* clone_bool(PhiNode* phi);
1535 
1536 
1537   // Rework addressing expressions to get the most loop-invariant stuff
1538   // moved out.  We'd like to do all associative operators, but it's especially
1539   // important (common) to do address expressions.
1540   Node* remix_address_expressions(Node* n);
1541   Node* remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt);
1542 
1543   // Convert add to muladd to generate MuladdS2I under certain criteria
1544   Node * convert_add_to_muladd(Node * n);
1545 
1546   // Attempt to use a conditional move instead of a phi/branch
1547   Node *conditional_move( Node *n );
1548 
1549   bool split_thru_phi_could_prevent_vectorization(Node* n, Node* n_blk);
1550 
1551   // Check for aggressive application of 'split-if' optimization,
1552   // using basic block level info.
1553   void  split_if_with_blocks     ( VectorSet &visited, Node_Stack &nstack);
1554   Node *split_if_with_blocks_pre ( Node *n );
1555   void  split_if_with_blocks_post( Node *n );
1556   Node *has_local_phi_input( Node *n );
1557   // Mark an IfNode as being dominated by a prior test,
1558   // without actually altering the CFG (and hence IDOM info).
1559   void dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip = false, bool pin_array_access_nodes = false);
1560   void rewire_safe_outputs_to_dominator(Node* source, Node* dominator, bool pin_array_access_nodes);
1561 
1562   // Split Node 'n' through merge point
1563   RegionNode* split_thru_region(Node* n, RegionNode* region);
1564   // Split Node 'n' through merge point if there is enough win.
1565   Node *split_thru_phi( Node *n, Node *region, int policy );
1566   // Found an If getting its condition-code input from a Phi in the
1567   // same block.  Split thru the Region.
1568   void do_split_if(Node *iff, RegionNode** new_false_region = nullptr, RegionNode** new_true_region = nullptr);
1569 
1570   // Conversion of fill/copy patterns into intrinsic versions
1571   bool do_intrinsify_fill();
1572   bool intrinsify_fill(IdealLoopTree* lpt);
1573   bool match_fill_loop(IdealLoopTree* lpt, Node*& store, Node*& store_value,
1574                        Node*& shift, Node*& offset);
1575 
1576 private:
1577   // Return a type based on condition control flow
1578   const TypeInt* filtered_type( Node *n, Node* n_ctrl);
1579   const TypeInt* filtered_type( Node *n ) { return filtered_type(n, nullptr); }
1580  // Helpers for filtered type
1581   const TypeInt* filtered_type_from_dominators( Node* val, Node *val_ctrl);
1582 
1583   // Helper functions
1584   Node *spinup( Node *iff, Node *new_false, Node *new_true, Node *region, Node *phi, small_cache *cache );
1585   Node *find_use_block( Node *use, Node *def, Node *old_false, Node *new_false, Node *old_true, Node *new_true );
1586   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 );
1587   bool split_up( Node *n, Node *blk1, Node *blk2 );
1588 
1589   Node* place_outside_loop(Node* useblock, IdealLoopTree* loop) const;
1590   Node* try_move_store_before_loop(Node* n, Node *n_ctrl);
1591   void try_move_store_after_loop(Node* n);
1592   void move_flat_array_check_out_of_loop(Node* n);
1593   bool identical_backtoback_ifs(Node *n);
1594   bool flat_array_element_type_check(Node *n);
1595   bool can_split_if(Node *n_ctrl);
1596   bool cannot_split_division(const Node* n, const Node* region) const;
1597   static bool is_divisor_loop_phi(const Node* divisor, const Node* loop);
1598   bool loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const;
1599 
1600   // Determine if a method is too big for a/another round of split-if, based on
1601   // a magic (approximate) ratio derived from the equally magic constant 35000,
1602   // previously used for this purpose (but without relating to the node limit).
1603   bool must_throttle_split_if() {
1604     uint threshold = C->max_node_limit() * 2 / 5;
1605     return C->live_nodes() > threshold;
1606   }
1607 
1608   // A simplistic node request tracking mechanism, where
1609   //   = UINT_MAX   Request not valid or made final.
1610   //   < UINT_MAX   Nodes currently requested (estimate).
1611   uint _nodes_required;
1612 
1613   enum { REQUIRE_MIN = 70 };
1614 
1615   uint nodes_required() const { return _nodes_required; }
1616 
1617   // Given the _currently_  available number of nodes, check  whether there is
1618   // "room" for an additional request or not, considering the already required
1619   // number of  nodes.  Return TRUE if  the new request is  exceeding the node
1620   // budget limit, otherwise return FALSE.  Note that this interpretation will
1621   // act pessimistic on  additional requests when new nodes  have already been
1622   // generated since the 'begin'.  This behaviour fits with the intention that
1623   // node estimates/requests should be made upfront.
1624   bool exceeding_node_budget(uint required = 0) {
1625     assert(C->live_nodes() < C->max_node_limit(), "sanity");
1626     uint available = C->max_node_limit() - C->live_nodes();
1627     return available < required + _nodes_required + REQUIRE_MIN;
1628   }
1629 
1630   uint require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1631     precond(require > 0);
1632     _nodes_required += MAX2(require, minreq);
1633     return _nodes_required;
1634   }
1635 
1636   bool may_require_nodes(uint require, uint minreq = REQUIRE_MIN) {
1637     return !exceeding_node_budget(require) && require_nodes(require, minreq) > 0;
1638   }
1639 
1640   uint require_nodes_begin() {
1641     assert(_nodes_required == UINT_MAX, "Bad state (begin).");
1642     _nodes_required = 0;
1643     return C->live_nodes();
1644   }
1645 
1646   // When a node request is final,  optionally check that the requested number
1647   // of nodes was  reasonably correct with respect to the  number of new nodes
1648   // introduced since the last 'begin'. Always check that we have not exceeded
1649   // the maximum node limit.
1650   void require_nodes_final(uint live_at_begin, bool check_estimate) {
1651     assert(_nodes_required < UINT_MAX, "Bad state (final).");
1652 
1653 #ifdef ASSERT
1654     if (check_estimate) {
1655       // Check that the node budget request was not off by too much (x2).
1656       // Should this be the case we _surely_ need to improve the estimates
1657       // used in our budget calculations.
1658       if (C->live_nodes() - live_at_begin > 2 * _nodes_required) {
1659         log_info(compilation)("Bad node estimate: actual = %d >> request = %d",
1660                               C->live_nodes() - live_at_begin, _nodes_required);
1661       }
1662     }
1663 #endif
1664     // Assert that we have stayed within the node budget limit.
1665     assert(C->live_nodes() < C->max_node_limit(),
1666            "Exceeding node budget limit: %d + %d > %d (request = %d)",
1667            C->live_nodes() - live_at_begin, live_at_begin,
1668            C->max_node_limit(), _nodes_required);
1669 
1670     _nodes_required = UINT_MAX;
1671   }
1672 
1673  public:
1674   // Clone Parse Predicates to slow and fast loop when unswitching a loop
1675   void clone_parse_and_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, Node_List& old_new,
1676                                                                IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1677  private:
1678   void clone_loop_predication_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1679                                                             const PredicateBlock* predicate_block,
1680                                                             Deoptimization::DeoptReason reason, IfProjNode*& iffast_pred,
1681                                                             IfProjNode*& ifslow_pred);
1682   void clone_parse_predicate_to_unswitched_loops(const PredicateBlock* predicate_block, Deoptimization::DeoptReason reason,
1683                                                  IfProjNode*& iffast_pred, IfProjNode*& ifslow_pred);
1684   IfProjNode* clone_parse_predicate_to_unswitched_loop(ParsePredicateSuccessProj* parse_predicate_proj, Node* new_entry,
1685                                                        Deoptimization::DeoptReason reason, bool slow_loop);
1686   void clone_assertion_predicates_to_unswitched_loop(IdealLoopTree* loop, const Node_List& old_new,
1687                                                      Deoptimization::DeoptReason reason, IfProjNode* old_predicate_proj,
1688                                                      ParsePredicateSuccessProj* fast_loop_parse_predicate_proj,
1689                                                      ParsePredicateSuccessProj* slow_loop_parse_predicate_proj);
1690   IfProjNode* clone_assertion_predicate_for_unswitched_loops(IfNode* template_assertion_predicate, IfProjNode* predicate,
1691                                                              Deoptimization::DeoptReason reason,
1692                                                              ParsePredicateSuccessProj* parse_predicate_proj);
1693   static void check_cloned_parse_predicate_for_unswitching(const Node* new_entry, bool is_fast_loop) PRODUCT_RETURN;
1694 
1695   bool _created_loop_node;
1696   DEBUG_ONLY(void dump_idoms(Node* early, Node* wrong_lca);)
1697   NOT_PRODUCT(void dump_idoms_in_reverse(const Node* n, const Node_List& idom_list) const;)
1698 
1699 public:
1700   void set_created_loop_node() { _created_loop_node = true; }
1701   bool created_loop_node()     { return _created_loop_node; }
1702   void register_new_node(Node* n, Node* blk);
1703   void register_new_node_with_ctrl_of(Node* new_node, Node* ctrl_of) {
1704     register_new_node(new_node, get_ctrl(ctrl_of));
1705   }
1706 
1707   Node* clone_and_register(Node* n, Node* ctrl) {
1708     n = n->clone();
1709     register_new_node(n, ctrl);
1710     return n;
1711   }
1712 
1713 #ifdef ASSERT
1714   void dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA);
1715 #endif
1716 
1717 #ifndef PRODUCT
1718   void dump() const;
1719   void dump_idom(Node* n) const { dump_idom(n, 1000); } // For debugging
1720   void dump_idom(Node* n, uint count) const;
1721   void get_idoms(Node* n, uint count, Unique_Node_List& idoms) const;
1722   void dump(IdealLoopTree* loop, uint rpo_idx, Node_List &rpo_list) const;
1723   IdealLoopTree* get_loop_idx(Node* n) const {
1724     // Dead nodes have no loop, so return the top level loop instead
1725     return _loop_or_ctrl[n->_idx] ? (IdealLoopTree*)_loop_or_ctrl[n->_idx] : _ltree_root;
1726   }
1727   // Print some stats
1728   static void print_statistics();
1729   static int _loop_invokes;     // Count of PhaseIdealLoop invokes
1730   static int _loop_work;        // Sum of PhaseIdealLoop x _unique
1731   static volatile int _long_loop_candidates;
1732   static volatile int _long_loop_nests;
1733   static volatile int _long_loop_counted_loops;
1734 #endif
1735 
1736 #ifdef ASSERT
1737   void verify() const;
1738   bool verify_idom_and_nodes(Node* root, const PhaseIdealLoop* phase_verify) const;
1739   bool verify_idom(Node* n, const PhaseIdealLoop* phase_verify) const;
1740   bool verify_loop_ctrl(Node* n, const PhaseIdealLoop* phase_verify) const;
1741 #endif
1742 
1743   void rpo(Node* start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list) const;
1744 
1745   void check_counted_loop_shape(IdealLoopTree* loop, Node* x, BasicType bt) NOT_DEBUG_RETURN;
1746 
1747   LoopNode* create_inner_head(IdealLoopTree* loop, BaseCountedLoopNode* head, IfNode* exit_test);
1748 
1749 
1750   int extract_long_range_checks(const IdealLoopTree* loop, jint stride_con, int iters_limit, PhiNode* phi,
1751                                 Node_List &range_checks);
1752 
1753   void transform_long_range_checks(int stride_con, const Node_List &range_checks, Node* outer_phi,
1754                                    Node* inner_iters_actual_int, Node* inner_phi,
1755                                    Node* iv_add, LoopNode* inner_head);
1756 
1757   Node* get_late_ctrl_with_anti_dep(LoadNode* n, Node* early, Node* LCA);
1758 
1759   bool ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl);
1760 
1761   bool ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop);
1762 
1763   Node* compute_early_ctrl(Node* n, Node* n_ctrl);
1764 
1765   void try_sink_out_of_loop(Node* n);
1766 
1767   Node* clamp(Node* R, Node* L, Node* H);
1768 
1769   bool safe_for_if_replacement(const Node* dom) const;
1770 
1771   void push_pinned_nodes_thru_region(IfNode* dom_if, Node* region);
1772 
1773   bool try_merge_identical_ifs(Node* n);
1774 
1775   void clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm);
1776 
1777   void fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
1778                       IdealLoopTree* parent, bool partial);
1779 
1780   void fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
1781                 Node* side_by_side_idom, CloneMap* cm, Node_List &worklist);
1782 
1783   void fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
1784                      uint new_counter, Node_List& old_new, Node_List& worklist, Node_List*& split_if_set,
1785                      Node_List*& split_bool_set, Node_List*& split_cex_set);
1786 
1787   void finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set);
1788 
1789   bool at_relevant_ctrl(Node* n, const Node* blk1, const Node* blk2);
1790 
1791   bool clone_cmp_loadklass_down(Node* n, const Node* blk1, const Node* blk2);
1792   void clone_loadklass_nodes_at_cmp_index(const Node* n, Node* cmp, int i);
1793   bool clone_cmp_down(Node* n, const Node* blk1, const Node* blk2);
1794   void clone_template_assertion_expression_down(Node* node);
1795 
1796   Node* similar_subtype_check(const Node* x, Node* r_in);
1797 
1798   void update_addp_chain_base(Node* x, Node* old_base, Node* new_base);
1799 
1800   bool can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x);
1801 
1802   void pin_array_access_nodes_dependent_on(Node* ctrl);
1803 
1804   void collect_flat_array_checks(const IdealLoopTree* loop, Node_List& flat_array_checks) const;
1805 
1806   Node* ensure_node_and_inputs_are_above_pre_end(CountedLoopEndNode* pre_end, Node* node);
1807 };
1808 
1809 
1810 class AutoNodeBudget : public StackObj
1811 {
1812 public:
1813   enum budget_check_t { BUDGET_CHECK, NO_BUDGET_CHECK };
1814 
1815   AutoNodeBudget(PhaseIdealLoop* phase, budget_check_t chk = BUDGET_CHECK)
1816     : _phase(phase),
1817       _check_at_final(chk == BUDGET_CHECK),
1818       _nodes_at_begin(0)
1819   {
1820     precond(_phase != nullptr);
1821 
1822     _nodes_at_begin = _phase->require_nodes_begin();
1823   }
1824 
1825   ~AutoNodeBudget() {
1826 #ifndef PRODUCT
1827     if (TraceLoopOpts) {
1828       uint request = _phase->nodes_required();
1829       uint delta   = _phase->C->live_nodes() - _nodes_at_begin;
1830 
1831       if (request < delta) {
1832         tty->print_cr("Exceeding node budget: %d < %d", request, delta);
1833       } else {
1834         uint const REQUIRE_MIN = PhaseIdealLoop::REQUIRE_MIN;
1835         // Identify the worst estimates as "poor" ones.
1836         if (request > REQUIRE_MIN && delta > 0) {
1837           if ((delta >  REQUIRE_MIN && request >  3 * delta) ||
1838               (delta <= REQUIRE_MIN && request > 10 * delta)) {
1839             tty->print_cr("Poor node estimate: %d >> %d", request, delta);
1840           }
1841         }
1842       }
1843     }
1844 #endif // PRODUCT
1845     _phase->require_nodes_final(_nodes_at_begin, _check_at_final);
1846   }
1847 
1848 private:
1849   PhaseIdealLoop* _phase;
1850   bool _check_at_final;
1851   uint _nodes_at_begin;
1852 };
1853 
1854 inline Node* IdealLoopTree::tail() {
1855   // Handle lazy update of _tail field.
1856   if (_tail->in(0) == nullptr) {
1857     _tail = _phase->get_ctrl(_tail);
1858   }
1859   return _tail;
1860 }
1861 
1862 inline Node* IdealLoopTree::head() {
1863   // Handle lazy update of _head field.
1864   if (_head->in(0) == nullptr) {
1865     _head = _phase->get_ctrl(_head);
1866   }
1867   return _head;
1868 }
1869 
1870 // Iterate over the loop tree using a preorder, left-to-right traversal.
1871 //
1872 // Example that visits all counted loops from within PhaseIdealLoop
1873 //
1874 //  for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
1875 //   IdealLoopTree* lpt = iter.current();
1876 //   if (!lpt->is_counted()) continue;
1877 //   ...
1878 class LoopTreeIterator : public StackObj {
1879 private:
1880   IdealLoopTree* _root;
1881   IdealLoopTree* _curnt;
1882 
1883 public:
1884   LoopTreeIterator(IdealLoopTree* root) : _root(root), _curnt(root) {}
1885 
1886   bool done() { return _curnt == nullptr; }       // Finished iterating?
1887 
1888   void next();                                 // Advance to next loop tree
1889 
1890   IdealLoopTree* current() { return _curnt; }  // Return current value of iterator.
1891 };
1892 
1893 // Compute probability of reaching some CFG node from a fixed
1894 // dominating CFG node
1895 class PathFrequency {
1896 private:
1897   Node* _dom; // frequencies are computed relative to this node
1898   Node_Stack _stack;
1899   GrowableArray<float> _freqs_stack; // keep track of intermediate result at regions
1900   GrowableArray<float> _freqs; // cache frequencies
1901   PhaseIdealLoop* _phase;
1902 
1903   float check_and_truncate_frequency(float f) {
1904     assert(f >= 0, "Incorrect frequency");
1905     // We do not perform an exact (f <= 1) check
1906     // this would be error prone with rounding of floats.
1907     // Performing a check like (f <= 1+eps) would be of benefit,
1908     // however, it is not evident how to determine such an eps,
1909     // given that an arbitrary number of add/mul operations
1910     // are performed on these frequencies.
1911     return (f > 1) ? 1 : f;
1912   }
1913 
1914 public:
1915   PathFrequency(Node* dom, PhaseIdealLoop* phase)
1916     : _dom(dom), _stack(0), _phase(phase) {
1917   }
1918 
1919   float to(Node* n);
1920 };
1921 
1922 // Class to clone a data node graph by taking a list of data nodes. This is done in 2 steps:
1923 //   1. Clone the data nodes
1924 //   2. Fix the cloned data inputs pointing to the old nodes to the cloned inputs by using an old->new mapping.
1925 class DataNodeGraph : public StackObj {
1926   PhaseIdealLoop* const _phase;
1927   const Unique_Node_List& _data_nodes;
1928   OrigToNewHashtable _orig_to_new;
1929 
1930  public:
1931   DataNodeGraph(const Unique_Node_List& data_nodes, PhaseIdealLoop* phase)
1932       : _phase(phase),
1933         _data_nodes(data_nodes),
1934         // Use 107 as best guess which is the first resize value in ResizeableResourceHashtable::large_table_sizes.
1935         _orig_to_new(107, MaxNodeLimit)
1936   {
1937 #ifdef ASSERT
1938     for (uint i = 0; i < data_nodes.size(); i++) {
1939       assert(!data_nodes[i]->is_CFG(), "only data nodes");
1940     }
1941 #endif
1942   }
1943   NONCOPYABLE(DataNodeGraph);
1944 
1945  private:
1946   void clone(Node* node, Node* new_ctrl);
1947   void clone_data_nodes(Node* new_ctrl);
1948   void clone_data_nodes_and_transform_opaque_loop_nodes(const TransformStrategyForOpaqueLoopNodes& transform_strategy,
1949                                                         Node* new_ctrl);
1950   void rewire_clones_to_cloned_inputs();
1951   void transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node);
1952 
1953  public:
1954   // Clone the provided data node collection and rewire the clones in such a way to create an identical graph copy.
1955   // Set 'new_ctrl' as ctrl for the cloned nodes.
1956   const OrigToNewHashtable& clone(Node* new_ctrl) {
1957     assert(_orig_to_new.number_of_entries() == 0, "should not call this method twice in a row");
1958     clone_data_nodes(new_ctrl);
1959     rewire_clones_to_cloned_inputs();
1960     return _orig_to_new;
1961   }
1962 
1963   // Create a copy of the data nodes provided to the constructor by doing the following:
1964   // Clone all non-OpaqueLoop* nodes and rewire them to create an identical subgraph copy. For the OpaqueLoop* nodes,
1965   // apply the provided transformation strategy and include the transformed node into the subgraph copy to get a complete
1966   // "cloned-and-transformed" graph copy. For all newly cloned nodes (which could also be new OpaqueLoop* nodes), set
1967   // `new_ctrl` as ctrl.
1968   const OrigToNewHashtable& clone_with_opaque_loop_transform_strategy(
1969       const TransformStrategyForOpaqueLoopNodes& transform_strategy,
1970       Node* new_ctrl) {
1971     clone_data_nodes_and_transform_opaque_loop_nodes(transform_strategy, new_ctrl);
1972     rewire_clones_to_cloned_inputs();
1973     return _orig_to_new;
1974   }
1975 };
1976 #endif // SHARE_OPTO_LOOPNODE_HPP