1 /*
   2  * Copyright (c) 1999, 2025, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "gc/shared/barrierSet.hpp"
  26 #include "gc/shared/c2/barrierSetC2.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "memory/resourceArea.hpp"
  29 #include "opto/addnode.hpp"
  30 #include "opto/callnode.hpp"
  31 #include "opto/castnode.hpp"
  32 #include "opto/connode.hpp"
  33 #include "opto/castnode.hpp"
  34 #include "opto/divnode.hpp"
  35 #include "opto/loopnode.hpp"
  36 #include "opto/matcher.hpp"
  37 #include "opto/mulnode.hpp"
  38 #include "opto/movenode.hpp"
  39 #include "opto/opaquenode.hpp"
  40 #include "opto/rootnode.hpp"
  41 #include "opto/subnode.hpp"
  42 #include "opto/subtypenode.hpp"
  43 #include "opto/superword.hpp"
  44 #include "opto/vectornode.hpp"
  45 #include "utilities/macros.hpp"
  46 
  47 //=============================================================================
  48 //------------------------------split_thru_phi---------------------------------
  49 // Split Node 'n' through merge point if there is enough win.
  50 Node* PhaseIdealLoop::split_thru_phi(Node* n, Node* region, int policy) {
  51   if ((n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) ||
  52       (n->Opcode() == Op_ConvL2I && n->bottom_type() != TypeInt::INT)) {
  53     // ConvI2L/ConvL2I may have type information on it which is unsafe to push up
  54     // so disable this for now
  55     return nullptr;
  56   }
  57 
  58   // Splitting range check CastIIs through a loop induction Phi can
  59   // cause new Phis to be created that are left unrelated to the loop
  60   // induction Phi and prevent optimizations (vectorization)
  61   if (n->Opcode() == Op_CastII && region->is_CountedLoop() &&
  62       n->in(1) == region->as_CountedLoop()->phi()) {
  63     return nullptr;
  64   }
  65 
  66   if (cannot_split_division(n, region)) {
  67     return nullptr;
  68   }
  69 
  70   int wins = 0;
  71   assert(!n->is_CFG(), "");
  72   assert(region->is_Region(), "");
  73 
  74   const Type* type = n->bottom_type();
  75   const TypeOopPtr* t_oop = _igvn.type(n)->isa_oopptr();
  76   Node* phi;
  77   if (t_oop != nullptr && t_oop->is_known_instance_field()) {
  78     int iid    = t_oop->instance_id();
  79     int index  = C->get_alias_index(t_oop);
  80     int offset = t_oop->offset();
  81     phi = new PhiNode(region, type, nullptr, iid, index, offset);
  82   } else {
  83     phi = PhiNode::make_blank(region, n);
  84   }
  85   uint old_unique = C->unique();
  86   for (uint i = 1; i < region->req(); i++) {
  87     Node* x;
  88     Node* the_clone = nullptr;
  89     if (region->in(i) == C->top()) {
  90       x = C->top();             // Dead path?  Use a dead data op
  91     } else {
  92       x = n->clone();           // Else clone up the data op
  93       the_clone = x;            // Remember for possible deletion.
  94       // Alter data node to use pre-phi inputs
  95       if (n->in(0) == region)
  96         x->set_req( 0, region->in(i) );
  97       for (uint j = 1; j < n->req(); j++) {
  98         Node* in = n->in(j);
  99         if (in->is_Phi() && in->in(0) == region)
 100           x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
 101       }
 102     }
 103     // Check for a 'win' on some paths
 104     const Type* t = x->Value(&_igvn);
 105 
 106     bool singleton = t->singleton();
 107 
 108     // A TOP singleton indicates that there are no possible values incoming
 109     // along a particular edge. In most cases, this is OK, and the Phi will
 110     // be eliminated later in an Ideal call. However, we can't allow this to
 111     // happen if the singleton occurs on loop entry, as the elimination of
 112     // the PhiNode may cause the resulting node to migrate back to a previous
 113     // loop iteration.
 114     if (singleton && t == Type::TOP) {
 115       // Is_Loop() == false does not confirm the absence of a loop (e.g., an
 116       // irreducible loop may not be indicated by an affirmative is_Loop());
 117       // therefore, the only top we can split thru a phi is on a backedge of
 118       // a loop.
 119       singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
 120     }
 121 
 122     if (singleton) {
 123       wins++;
 124       x = makecon(t);
 125     } else {
 126       // We now call Identity to try to simplify the cloned node.
 127       // Note that some Identity methods call phase->type(this).
 128       // Make sure that the type array is big enough for
 129       // our new node, even though we may throw the node away.
 130       // (Note: This tweaking with igvn only works because x is a new node.)
 131       _igvn.set_type(x, t);
 132       // If x is a TypeNode, capture any more-precise type permanently into Node
 133       // otherwise it will be not updated during igvn->transform since
 134       // igvn->type(x) is set to x->Value() already.
 135       x->raise_bottom_type(t);
 136       Node* y = x->Identity(&_igvn);
 137       if (y != x) {
 138         wins++;
 139         x = y;
 140       } else {
 141         y = _igvn.hash_find(x);
 142         if (y == nullptr) {
 143           y = similar_subtype_check(x, region->in(i));
 144         }
 145         if (y) {
 146           wins++;
 147           x = y;
 148         } else {
 149           // Else x is a new node we are keeping
 150           // We do not need register_new_node_with_optimizer
 151           // because set_type has already been called.
 152           _igvn._worklist.push(x);
 153         }
 154       }
 155     }
 156 
 157     phi->set_req( i, x );
 158 
 159     if (the_clone == nullptr) {
 160       continue;
 161     }
 162 
 163     if (the_clone != x) {
 164       _igvn.remove_dead_node(the_clone);
 165     } else if (region->is_Loop() && i == LoopNode::LoopBackControl &&
 166                n->is_Load() && can_move_to_inner_loop(n, region->as_Loop(), x)) {
 167       // it is not a win if 'x' moved from an outer to an inner loop
 168       // this edge case can only happen for Load nodes
 169       wins = 0;
 170       break;
 171     }
 172   }
 173   // Too few wins?
 174   if (wins <= policy) {
 175     _igvn.remove_dead_node(phi);
 176     return nullptr;
 177   }
 178 
 179   // Record Phi
 180   register_new_node( phi, region );
 181 
 182   for (uint i2 = 1; i2 < phi->req(); i2++) {
 183     Node *x = phi->in(i2);
 184     // If we commoned up the cloned 'x' with another existing Node,
 185     // the existing Node picks up a new use.  We need to make the
 186     // existing Node occur higher up so it dominates its uses.
 187     Node *old_ctrl;
 188     IdealLoopTree *old_loop;
 189 
 190     if (x->is_Con()) {
 191       assert(get_ctrl(x) == C->root(), "constant control is not root");
 192       continue;
 193     }
 194     // The occasional new node
 195     if (x->_idx >= old_unique) {     // Found a new, unplaced node?
 196       old_ctrl = nullptr;
 197       old_loop = nullptr;               // Not in any prior loop
 198     } else {
 199       old_ctrl = get_ctrl(x);
 200       old_loop = get_loop(old_ctrl); // Get prior loop
 201     }
 202     // New late point must dominate new use
 203     Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
 204     if (new_ctrl == old_ctrl) // Nothing is changed
 205       continue;
 206 
 207     IdealLoopTree *new_loop = get_loop(new_ctrl);
 208 
 209     // Don't move x into a loop if its uses are
 210     // outside of loop. Otherwise x will be cloned
 211     // for each use outside of this loop.
 212     IdealLoopTree *use_loop = get_loop(region);
 213     if (!new_loop->is_member(use_loop) &&
 214         (old_loop == nullptr || !new_loop->is_member(old_loop))) {
 215       // Take early control, later control will be recalculated
 216       // during next iteration of loop optimizations.
 217       new_ctrl = get_early_ctrl(x);
 218       new_loop = get_loop(new_ctrl);
 219     }
 220     // Set new location
 221     set_ctrl(x, new_ctrl);
 222     // If changing loop bodies, see if we need to collect into new body
 223     if (old_loop != new_loop) {
 224       if (old_loop && !old_loop->_child)
 225         old_loop->_body.yank(x);
 226       if (!new_loop->_child)
 227         new_loop->_body.push(x);  // Collect body info
 228     }
 229   }
 230 
 231   return phi;
 232 }
 233 
 234 // Test whether node 'x' can move into an inner loop relative to node 'n'.
 235 // Note: The test is not exact. Returns true if 'x' COULD end up in an inner loop,
 236 // BUT it can also return true and 'x' is in the outer loop
 237 bool PhaseIdealLoop::can_move_to_inner_loop(Node* n, LoopNode* n_loop, Node* x) {
 238   IdealLoopTree* n_loop_tree = get_loop(n_loop);
 239   IdealLoopTree* x_loop_tree = get_loop(get_early_ctrl(x));
 240   // x_loop_tree should be outer or same loop as n_loop_tree
 241   return !x_loop_tree->is_member(n_loop_tree);
 242 }
 243 
 244 // Subtype checks that carry profile data don't common so look for a replacement by following edges
 245 Node* PhaseIdealLoop::similar_subtype_check(const Node* x, Node* r_in) {
 246   if (x->is_SubTypeCheck()) {
 247     Node* in1 = x->in(1);
 248     for (DUIterator_Fast imax, i = in1->fast_outs(imax); i < imax; i++) {
 249       Node* u = in1->fast_out(i);
 250       if (u != x && u->is_SubTypeCheck() && u->in(1) == x->in(1) && u->in(2) == x->in(2)) {
 251         for (DUIterator_Fast jmax, j = u->fast_outs(jmax); j < jmax; j++) {
 252           Node* bol = u->fast_out(j);
 253           for (DUIterator_Fast kmax, k = bol->fast_outs(kmax); k < kmax; k++) {
 254             Node* iff = bol->fast_out(k);
 255             // Only dominating subtype checks are interesting: otherwise we risk replacing a subtype check by another with
 256             // unrelated profile
 257             if (iff->is_If() && is_dominator(iff, r_in)) {
 258               return u;
 259             }
 260           }
 261         }
 262       }
 263     }
 264   }
 265   return nullptr;
 266 }
 267 
 268 // Return true if 'n' is a Div or Mod node (without zero check If node which was removed earlier) with a loop phi divisor
 269 // of a trip-counted (integer or long) loop with a backedge input that could be zero (include zero in its type range). In
 270 // this case, we cannot split the division to the backedge as it could freely float above the loop exit check resulting in
 271 // a division by zero. This situation is possible because the type of an increment node of an iv phi (trip-counter) could
 272 // include zero while the iv phi does not (see PhiNode::Value() for trip-counted loops where we improve types of iv phis).
 273 // We also need to check other loop phis as they could have been created in the same split-if pass when applying
 274 // PhaseIdealLoop::split_thru_phi() to split nodes through an iv phi.
 275 bool PhaseIdealLoop::cannot_split_division(const Node* n, const Node* region) const {
 276   const Type* zero;
 277   switch (n->Opcode()) {
 278     case Op_DivI:
 279     case Op_ModI:
 280     case Op_UDivI:
 281     case Op_UModI:
 282       zero = TypeInt::ZERO;
 283       break;
 284     case Op_DivL:
 285     case Op_ModL:
 286     case Op_UDivL:
 287     case Op_UModL:
 288       zero = TypeLong::ZERO;
 289       break;
 290     default:
 291       return false;
 292   }
 293 
 294   if (n->in(0) != nullptr) {
 295     // Cannot split through phi if Div or Mod node has a control dependency to a zero check.
 296     return true;
 297   }
 298 
 299   Node* divisor = n->in(2);
 300   return is_divisor_loop_phi(divisor, region) &&
 301          loop_phi_backedge_type_contains_zero(divisor, zero);
 302 }
 303 
 304 bool PhaseIdealLoop::is_divisor_loop_phi(const Node* divisor, const Node* loop) {
 305   return loop->is_Loop() && divisor->is_Phi() && divisor->in(0) == loop;
 306 }
 307 
 308 bool PhaseIdealLoop::loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const {
 309     return _igvn.type(phi_divisor->in(LoopNode::LoopBackControl))->filter_speculative(zero) != Type::TOP;
 310 }
 311 
 312 //------------------------------dominated_by------------------------------------
 313 // Replace the dominated test with an obvious true or false.  Place it on the
 314 // IGVN worklist for later cleanup.  Move control-dependent data Nodes on the
 315 // live path up to the dominating control.
 316 void PhaseIdealLoop::dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip, bool pin_array_access_nodes) {
 317   if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
 318 
 319   // prevdom is the dominating projection of the dominating test.
 320   assert(iff->Opcode() == Op_If ||
 321          iff->Opcode() == Op_CountedLoopEnd ||
 322          iff->Opcode() == Op_LongCountedLoopEnd ||
 323          iff->Opcode() == Op_RangeCheck ||
 324          iff->Opcode() == Op_ParsePredicate,
 325         "Check this code when new subtype is added");
 326 
 327   int pop = prevdom->Opcode();
 328   assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
 329   if (flip) {
 330     if (pop == Op_IfTrue)
 331       pop = Op_IfFalse;
 332     else
 333       pop = Op_IfTrue;
 334   }
 335   // 'con' is set to true or false to kill the dominated test.
 336   Node* con = makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
 337   // Hack the dominated test
 338   _igvn.replace_input_of(iff, 1, con);
 339 
 340   // If I don't have a reachable TRUE and FALSE path following the IfNode then
 341   // I can assume this path reaches an infinite loop.  In this case it's not
 342   // important to optimize the data Nodes - either the whole compilation will
 343   // be tossed or this path (and all data Nodes) will go dead.
 344   if (iff->outcnt() != 2) {
 345     return;
 346   }
 347 
 348   // Make control-dependent data Nodes on the live path (path that will remain
 349   // once the dominated IF is removed) become control-dependent on the
 350   // dominating projection.
 351   Node* dp = iff->proj_out_or_null(pop == Op_IfTrue);
 352 
 353   if (dp == nullptr) {
 354     return;
 355   }
 356 
 357   rewire_safe_outputs_to_dominator(dp, prevdom, pin_array_access_nodes);
 358 }
 359 
 360 void PhaseIdealLoop::rewire_safe_outputs_to_dominator(Node* source, Node* dominator, const bool pin_array_access_nodes) {
 361   IdealLoopTree* old_loop = get_loop(source);
 362 
 363   for (DUIterator_Fast imax, i = source->fast_outs(imax); i < imax; i++) {
 364     Node* out = source->fast_out(i); // Control-dependent node
 365     // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
 366     if (out->depends_only_on_test() && _igvn.no_dependent_zero_check(out)) {
 367       assert(out->in(0) == source, "must be control dependent on source");
 368       _igvn.replace_input_of(out, 0, dominator);
 369       if (pin_array_access_nodes) {
 370         // Because of Loop Predication, Loads and range check Cast nodes that are control dependent on this range
 371         // check (that is about to be removed) now depend on multiple dominating Hoisted Check Predicates. After the
 372         // removal of this range check, these control dependent nodes end up at the lowest/nearest dominating predicate
 373         // in the graph. To ensure that these Loads/Casts do not float above any of the dominating checks (even when the
 374         // lowest dominating check is later replaced by yet another dominating check), we need to pin them at the lowest
 375         // dominating check.
 376         Node* clone = out->pin_array_access_node();
 377         if (clone != nullptr) {
 378           clone = _igvn.register_new_node_with_optimizer(clone, out);
 379           _igvn.replace_node(out, clone);
 380           out = clone;
 381         }
 382       }
 383       set_early_ctrl(out, false);
 384       IdealLoopTree* new_loop = get_loop(get_ctrl(out));
 385       if (old_loop != new_loop) {
 386         if (!old_loop->_child) {
 387           old_loop->_body.yank(out);
 388         }
 389         if (!new_loop->_child) {
 390           new_loop->_body.push(out);
 391         }
 392       }
 393       --i;
 394       --imax;
 395     }
 396   }
 397 }
 398 
 399 //------------------------------has_local_phi_input----------------------------
 400 // Return TRUE if 'n' has Phi inputs from its local block and no other
 401 // block-local inputs (all non-local-phi inputs come from earlier blocks)
 402 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
 403   Node *n_ctrl = get_ctrl(n);
 404   // See if some inputs come from a Phi in this block, or from before
 405   // this block.
 406   uint i;
 407   for( i = 1; i < n->req(); i++ ) {
 408     Node *phi = n->in(i);
 409     if( phi->is_Phi() && phi->in(0) == n_ctrl )
 410       break;
 411   }
 412   if( i >= n->req() )
 413     return nullptr;                // No Phi inputs; nowhere to clone thru
 414 
 415   // Check for inputs created between 'n' and the Phi input.  These
 416   // must split as well; they have already been given the chance
 417   // (courtesy of a post-order visit) and since they did not we must
 418   // recover the 'cost' of splitting them by being very profitable
 419   // when splitting 'n'.  Since this is unlikely we simply give up.
 420   for( i = 1; i < n->req(); i++ ) {
 421     Node *m = n->in(i);
 422     if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
 423       // We allow the special case of AddP's with no local inputs.
 424       // This allows us to split-up address expressions.
 425       if (m->is_AddP() &&
 426           get_ctrl(m->in(AddPNode::Base)) != n_ctrl &&
 427           get_ctrl(m->in(AddPNode::Address)) != n_ctrl &&
 428           get_ctrl(m->in(AddPNode::Offset)) != n_ctrl) {
 429         // Move the AddP up to the dominating point. That's fine because control of m's inputs
 430         // must dominate get_ctrl(m) == n_ctrl and we just checked that the input controls are != n_ctrl.
 431         Node* c = find_non_split_ctrl(idom(n_ctrl));
 432         if (c->is_OuterStripMinedLoop()) {
 433           c->as_Loop()->verify_strip_mined(1);
 434           c = c->in(LoopNode::EntryControl);
 435         }
 436         set_ctrl_and_loop(m, c);
 437         continue;
 438       }
 439       return nullptr;
 440     }
 441     assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
 442   }
 443 
 444   return n_ctrl;
 445 }
 446 
 447 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
 448 Node* PhaseIdealLoop::remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt) {
 449   assert(bt == T_INT || bt == T_LONG, "only for integers");
 450   int n_op = n->Opcode();
 451 
 452   if (n_op == Op_LShift(bt)) {
 453     // Scale is loop invariant
 454     Node* scale = n->in(2);
 455     Node* scale_ctrl = get_ctrl(scale);
 456     IdealLoopTree* scale_loop = get_loop(scale_ctrl);
 457     if (n_loop == scale_loop || !scale_loop->is_member(n_loop)) {
 458       return nullptr;
 459     }
 460     const TypeInt* scale_t = scale->bottom_type()->isa_int();
 461     if (scale_t != nullptr && scale_t->is_con() && scale_t->get_con() >= 16) {
 462       return nullptr;              // Dont bother with byte/short masking
 463     }
 464     // Add must vary with loop (else shift would be loop-invariant)
 465     Node* add = n->in(1);
 466     Node* add_ctrl = get_ctrl(add);
 467     IdealLoopTree* add_loop = get_loop(add_ctrl);
 468     if (n_loop != add_loop) {
 469       return nullptr;  // happens w/ evil ZKM loops
 470     }
 471 
 472     // Convert I-V into I+ (0-V); same for V-I
 473     if (add->Opcode() == Op_Sub(bt) &&
 474         _igvn.type(add->in(1)) != TypeInteger::zero(bt)) {
 475       assert(add->Opcode() == Op_SubI || add->Opcode() == Op_SubL, "");
 476       Node* zero = integercon(0, bt);
 477       Node* neg = SubNode::make(zero, add->in(2), bt);
 478       register_new_node_with_ctrl_of(neg, add->in(2));
 479       add = AddNode::make(add->in(1), neg, bt);
 480       register_new_node(add, add_ctrl);
 481     }
 482     if (add->Opcode() != Op_Add(bt)) return nullptr;
 483     assert(add->Opcode() == Op_AddI || add->Opcode() == Op_AddL, "");
 484     // See if one add input is loop invariant
 485     Node* add_var = add->in(1);
 486     Node* add_var_ctrl = get_ctrl(add_var);
 487     IdealLoopTree* add_var_loop = get_loop(add_var_ctrl);
 488     Node* add_invar = add->in(2);
 489     Node* add_invar_ctrl = get_ctrl(add_invar);
 490     IdealLoopTree* add_invar_loop = get_loop(add_invar_ctrl);
 491     if (add_invar_loop == n_loop) {
 492       // Swap to find the invariant part
 493       add_invar = add_var;
 494       add_invar_ctrl = add_var_ctrl;
 495       add_invar_loop = add_var_loop;
 496       add_var = add->in(2);
 497     } else if (add_var_loop != n_loop) { // Else neither input is loop invariant
 498       return nullptr;
 499     }
 500     if (n_loop == add_invar_loop || !add_invar_loop->is_member(n_loop)) {
 501       return nullptr;              // No invariant part of the add?
 502     }
 503 
 504     // Yes!  Reshape address expression!
 505     Node* inv_scale = LShiftNode::make(add_invar, scale, bt);
 506     Node* inv_scale_ctrl =
 507             dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
 508             add_invar_ctrl : scale_ctrl;
 509     register_new_node(inv_scale, inv_scale_ctrl);
 510     Node* var_scale = LShiftNode::make(add_var, scale, bt);
 511     register_new_node(var_scale, n_ctrl);
 512     Node* var_add = AddNode::make(var_scale, inv_scale, bt);
 513     register_new_node(var_add, n_ctrl);
 514     _igvn.replace_node(n, var_add);
 515     return var_add;
 516   }
 517   return nullptr;
 518 }
 519 
 520 //------------------------------remix_address_expressions----------------------
 521 // Rework addressing expressions to get the most loop-invariant stuff
 522 // moved out.  We'd like to do all associative operators, but it's especially
 523 // important (common) to do address expressions.
 524 Node* PhaseIdealLoop::remix_address_expressions(Node* n) {
 525   if (!has_ctrl(n))  return nullptr;
 526   Node* n_ctrl = get_ctrl(n);
 527   IdealLoopTree* n_loop = get_loop(n_ctrl);
 528 
 529   // See if 'n' mixes loop-varying and loop-invariant inputs and
 530   // itself is loop-varying.
 531 
 532   // Only interested in binary ops (and AddP)
 533   if (n->req() < 3 || n->req() > 4) return nullptr;
 534 
 535   Node* n1_ctrl = get_ctrl(n->in(                    1));
 536   Node* n2_ctrl = get_ctrl(n->in(                    2));
 537   Node* n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
 538   IdealLoopTree* n1_loop = get_loop(n1_ctrl);
 539   IdealLoopTree* n2_loop = get_loop(n2_ctrl);
 540   IdealLoopTree* n3_loop = get_loop(n3_ctrl);
 541 
 542   // Does one of my inputs spin in a tighter loop than self?
 543   if ((n_loop->is_member(n1_loop) && n_loop != n1_loop) ||
 544       (n_loop->is_member(n2_loop) && n_loop != n2_loop) ||
 545       (n_loop->is_member(n3_loop) && n_loop != n3_loop)) {
 546     return nullptr;                // Leave well enough alone
 547   }
 548 
 549   // Is at least one of my inputs loop-invariant?
 550   if (n1_loop == n_loop &&
 551       n2_loop == n_loop &&
 552       n3_loop == n_loop) {
 553     return nullptr;                // No loop-invariant inputs
 554   }
 555 
 556   Node* res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_INT);
 557   if (res != nullptr) {
 558     return res;
 559   }
 560   res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_LONG);
 561   if (res != nullptr) {
 562     return res;
 563   }
 564 
 565   int n_op = n->Opcode();
 566   // Replace (I+V) with (V+I)
 567   if (n_op == Op_AddI ||
 568       n_op == Op_AddL ||
 569       n_op == Op_AddF ||
 570       n_op == Op_AddD ||
 571       n_op == Op_MulI ||
 572       n_op == Op_MulL ||
 573       n_op == Op_MulF ||
 574       n_op == Op_MulD) {
 575     if (n2_loop == n_loop) {
 576       assert(n1_loop != n_loop, "");
 577       n->swap_edges(1, 2);
 578     }
 579   }
 580 
 581   // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
 582   // but not if I2 is a constant. Skip for irreducible loops.
 583   if (n_op == Op_AddP && n_loop->_head->is_Loop()) {
 584     if (n2_loop == n_loop && n3_loop != n_loop) {
 585       if (n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con()) {
 586         Node* n22_ctrl = get_ctrl(n->in(2)->in(2));
 587         Node* n23_ctrl = get_ctrl(n->in(2)->in(3));
 588         IdealLoopTree* n22loop = get_loop(n22_ctrl);
 589         IdealLoopTree* n23_loop = get_loop(n23_ctrl);
 590         if (n22loop != n_loop && n22loop->is_member(n_loop) &&
 591             n23_loop == n_loop) {
 592           Node* add1 = new AddPNode(n->in(1), n->in(2)->in(2), n->in(3));
 593           // Stuff new AddP in the loop preheader
 594           register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
 595           Node* add2 = new AddPNode(n->in(1), add1, n->in(2)->in(3));
 596           register_new_node(add2, n_ctrl);
 597           _igvn.replace_node(n, add2);
 598           return add2;
 599         }
 600       }
 601     }
 602 
 603     // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
 604     if (n2_loop != n_loop && n3_loop == n_loop) {
 605       if (n->in(3)->Opcode() == Op_AddX) {
 606         Node* V = n->in(3)->in(1);
 607         Node* I = n->in(3)->in(2);
 608         if (is_member(n_loop,get_ctrl(V))) {
 609         } else {
 610           Node *tmp = V; V = I; I = tmp;
 611         }
 612         if (!is_member(n_loop,get_ctrl(I))) {
 613           Node* add1 = new AddPNode(n->in(1), n->in(2), I);
 614           // Stuff new AddP in the loop preheader
 615           register_new_node(add1, n_loop->_head->as_Loop()->skip_strip_mined(1)->in(LoopNode::EntryControl));
 616           Node* add2 = new AddPNode(n->in(1), add1, V);
 617           register_new_node(add2, n_ctrl);
 618           _igvn.replace_node(n, add2);
 619           return add2;
 620         }
 621       }
 622     }
 623   }
 624 
 625   return nullptr;
 626 }
 627 
 628 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
 629 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
 630   assert(n->Opcode() == Op_AddI, "sanity");
 631   Node * nn = nullptr;
 632   Node * in1 = n->in(1);
 633   Node * in2 = n->in(2);
 634   if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
 635     IdealLoopTree* loop_n = get_loop(get_ctrl(n));
 636     if (loop_n->is_counted() &&
 637         loop_n->_head->as_Loop()->is_valid_counted_loop(T_INT) &&
 638         Matcher::match_rule_supported(Op_MulAddVS2VI) &&
 639         Matcher::match_rule_supported(Op_MulAddS2I)) {
 640       Node* mul_in1 = in1->in(1);
 641       Node* mul_in2 = in1->in(2);
 642       Node* mul_in3 = in2->in(1);
 643       Node* mul_in4 = in2->in(2);
 644       if (mul_in1->Opcode() == Op_LoadS &&
 645           mul_in2->Opcode() == Op_LoadS &&
 646           mul_in3->Opcode() == Op_LoadS &&
 647           mul_in4->Opcode() == Op_LoadS) {
 648         IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
 649         IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
 650         IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
 651         IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
 652         IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
 653         IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
 654         // All nodes should be in the same counted loop.
 655         if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
 656             loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
 657           Node* adr1 = mul_in1->in(MemNode::Address);
 658           Node* adr2 = mul_in2->in(MemNode::Address);
 659           Node* adr3 = mul_in3->in(MemNode::Address);
 660           Node* adr4 = mul_in4->in(MemNode::Address);
 661           if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
 662             if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
 663                 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
 664               nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
 665               register_new_node_with_ctrl_of(nn, n);
 666               _igvn.replace_node(n, nn);
 667               return nn;
 668             } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
 669                        (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
 670               nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
 671               register_new_node_with_ctrl_of(nn, n);
 672               _igvn.replace_node(n, nn);
 673               return nn;
 674             }
 675           }
 676         }
 677       }
 678     }
 679   }
 680   return nn;
 681 }
 682 
 683 //------------------------------conditional_move-------------------------------
 684 // Attempt to replace a Phi with a conditional move.  We have some pretty
 685 // strict profitability requirements.  All Phis at the merge point must
 686 // be converted, so we can remove the control flow.  We need to limit the
 687 // number of c-moves to a small handful.  All code that was in the side-arms
 688 // of the CFG diamond is now speculatively executed.  This code has to be
 689 // "cheap enough".  We are pretty much limited to CFG diamonds that merge
 690 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
 691 Node *PhaseIdealLoop::conditional_move( Node *region ) {
 692 
 693   assert(region->is_Region(), "sanity check");
 694   if (region->req() != 3) return nullptr;
 695 
 696   // Check for CFG diamond
 697   Node *lp = region->in(1);
 698   Node *rp = region->in(2);
 699   if (!lp || !rp) return nullptr;
 700   Node *lp_c = lp->in(0);
 701   if (lp_c == nullptr || lp_c != rp->in(0) || !lp_c->is_If()) return nullptr;
 702   IfNode *iff = lp_c->as_If();
 703 
 704   // Check for ops pinned in an arm of the diamond.
 705   // Can't remove the control flow in this case
 706   if (lp->outcnt() > 1) return nullptr;
 707   if (rp->outcnt() > 1) return nullptr;
 708 
 709   IdealLoopTree* r_loop = get_loop(region);
 710   assert(r_loop == get_loop(iff), "sanity");
 711   // Always convert to CMOVE if all results are used only outside this loop.
 712   bool used_inside_loop = (r_loop == _ltree_root);
 713 
 714   // Check profitability
 715   int cost = 0;
 716   int phis = 0;
 717   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 718     Node *out = region->fast_out(i);
 719     if (!out->is_Phi()) continue; // Ignore other control edges, etc
 720     phis++;
 721     PhiNode* phi = out->as_Phi();
 722     BasicType bt = phi->type()->basic_type();
 723     switch (bt) {
 724     case T_DOUBLE:
 725     case T_FLOAT:
 726       if (C->use_cmove()) {
 727         continue; //TODO: maybe we want to add some cost
 728       }
 729       cost += Matcher::float_cmove_cost(); // Could be very expensive
 730       break;
 731     case T_LONG: {
 732       cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
 733     }
 734     case T_INT:                 // These all CMOV fine
 735     case T_ADDRESS: {           // (RawPtr)
 736       cost++;
 737       break;
 738     }
 739     case T_NARROWOOP: // Fall through
 740     case T_OBJECT: {            // Base oops are OK, but not derived oops
 741       const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
 742       // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
 743       // CMOVE'd derived pointer?  It's a CMOVE'd derived base.  Thus
 744       // CMOVE'ing a derived pointer requires we also CMOVE the base.  If we
 745       // have a Phi for the base here that we convert to a CMOVE all is well
 746       // and good.  But if the base is dead, we'll not make a CMOVE.  Later
 747       // the allocator will have to produce a base by creating a CMOVE of the
 748       // relevant bases.  This puts the allocator in the business of
 749       // manufacturing expensive instructions, generally a bad plan.
 750       // Just Say No to Conditionally-Moved Derived Pointers.
 751       if (tp && tp->offset() != 0)
 752         return nullptr;
 753       cost++;
 754       break;
 755     }
 756     default:
 757       return nullptr;              // In particular, can't do memory or I/O
 758     }
 759     // Add in cost any speculative ops
 760     for (uint j = 1; j < region->req(); j++) {
 761       Node *proj = region->in(j);
 762       Node *inp = phi->in(j);
 763       if (get_ctrl(inp) == proj) { // Found local op
 764         cost++;
 765         // Check for a chain of dependent ops; these will all become
 766         // speculative in a CMOV.
 767         for (uint k = 1; k < inp->req(); k++)
 768           if (get_ctrl(inp->in(k)) == proj)
 769             cost += ConditionalMoveLimit; // Too much speculative goo
 770       }
 771     }
 772     // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
 773     // This will likely Split-If, a higher-payoff operation.
 774     for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
 775       Node* use = phi->fast_out(k);
 776       if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
 777         cost += ConditionalMoveLimit;
 778       // Is there a use inside the loop?
 779       // Note: check only basic types since CMoveP is pinned.
 780       if (!used_inside_loop && is_java_primitive(bt)) {
 781         IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
 782         if (r_loop == u_loop || r_loop->is_member(u_loop)) {
 783           used_inside_loop = true;
 784         }
 785       }
 786     }
 787   }//for
 788   Node* bol = iff->in(1);
 789   assert(!bol->is_OpaqueInitializedAssertionPredicate(), "Initialized Assertion Predicates cannot form a diamond with Halt");
 790   if (bol->is_OpaqueTemplateAssertionPredicate()) {
 791     // Ignore Template Assertion Predicates with OpaqueTemplateAssertionPredicate nodes.
 792     return nullptr;
 793   }
 794   if (bol->is_OpaqueMultiversioning()) {
 795     assert(bol->as_OpaqueMultiversioning()->is_useless(), "Must be useless, i.e. fast main loop has already disappeared.");
 796     // Ignore multiversion_if that just lost its loops. The OpaqueMultiversioning is marked useless,
 797     // and will make the multiversion_if constant fold in the next IGVN round.
 798     return nullptr;
 799   }
 800   if (!bol->is_Bool()) {
 801     assert(false, "Expected Bool, but got %s", NodeClassNames[bol->Opcode()]);
 802     return nullptr;
 803   }
 804   int cmp_op = bol->in(1)->Opcode();
 805   if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode
 806     return nullptr;
 807   }
 808   // It is expensive to generate flags from a float compare.
 809   // Avoid duplicated float compare.
 810   if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return nullptr;
 811 
 812   float infrequent_prob = PROB_UNLIKELY_MAG(3);
 813   // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
 814   if (used_inside_loop) {
 815     if (cost >= ConditionalMoveLimit) return nullptr; // Too much goo
 816 
 817     // BlockLayoutByFrequency optimization moves infrequent branch
 818     // from hot path. No point in CMOV'ing in such case (110 is used
 819     // instead of 100 to take into account not exactness of float value).
 820     if (BlockLayoutByFrequency) {
 821       infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
 822     }
 823   }
 824   // Check for highly predictable branch.  No point in CMOV'ing if
 825   // we are going to predict accurately all the time.
 826   if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
 827     //keep going
 828   } else if (iff->_prob < infrequent_prob ||
 829       iff->_prob > (1.0f - infrequent_prob))
 830     return nullptr;
 831 
 832   // --------------
 833   // Now replace all Phis with CMOV's
 834   Node *cmov_ctrl = iff->in(0);
 835   uint flip = (lp->Opcode() == Op_IfTrue);
 836   Node_List wq;
 837   while (1) {
 838     PhiNode* phi = nullptr;
 839     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 840       Node *out = region->fast_out(i);
 841       if (out->is_Phi()) {
 842         phi = out->as_Phi();
 843         break;
 844       }
 845     }
 846     if (phi == nullptr || _igvn.type(phi) == Type::TOP || !CMoveNode::supported(_igvn.type(phi))) {
 847       break;
 848     }
 849     // Move speculative ops
 850     wq.push(phi);
 851     while (wq.size() > 0) {
 852       Node *n = wq.pop();
 853       for (uint j = 1; j < n->req(); j++) {
 854         Node* m = n->in(j);
 855         if (m != nullptr && !is_dominator(get_ctrl(m), cmov_ctrl)) {
 856           set_ctrl(m, cmov_ctrl);
 857           wq.push(m);
 858         }
 859       }
 860     }
 861     Node* cmov = CMoveNode::make(iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
 862     register_new_node(cmov, cmov_ctrl);
 863     _igvn.replace_node(phi, cmov);
 864 #ifndef PRODUCT
 865     if (TraceLoopOpts) {
 866       tty->print("CMOV  ");
 867       r_loop->dump_head();
 868       if (Verbose) {
 869         bol->in(1)->dump(1);
 870         cmov->dump(1);
 871       }
 872     }
 873     DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
 874 #endif
 875   }
 876 
 877   // The useless CFG diamond will fold up later; see the optimization in
 878   // RegionNode::Ideal.
 879   _igvn._worklist.push(region);
 880 
 881   return iff->in(1);
 882 }
 883 
 884 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
 885   for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
 886     Node* u = m->fast_out(i);
 887     if (u->is_CFG()) {
 888       if (u->is_NeverBranch()) {
 889         u = u->as_NeverBranch()->proj_out(0);
 890         enqueue_cfg_uses(u, wq);
 891       } else {
 892         wq.push(u);
 893       }
 894     }
 895   }
 896 }
 897 
 898 // Try moving a store out of a loop, right before the loop
 899 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
 900   // Store has to be first in the loop body
 901   IdealLoopTree *n_loop = get_loop(n_ctrl);
 902   if (n->is_Store() && n_loop != _ltree_root &&
 903       n_loop->is_loop() && n_loop->_head->is_Loop() &&
 904       n->in(0) != nullptr) {
 905     Node* address = n->in(MemNode::Address);
 906     Node* value = n->in(MemNode::ValueIn);
 907     Node* mem = n->in(MemNode::Memory);
 908     IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 909     IdealLoopTree* value_loop = get_loop(get_ctrl(value));
 910 
 911     // - address and value must be loop invariant
 912     // - memory must be a memory Phi for the loop
 913     // - Store must be the only store on this memory slice in the
 914     // loop: if there's another store following this one then value
 915     // written at iteration i by the second store could be overwritten
 916     // at iteration i+n by the first store: it's not safe to move the
 917     // first store out of the loop
 918     // - nothing must observe the memory Phi: it guarantees no read
 919     // before the store, we are also guaranteed the store post
 920     // dominates the loop head (ignoring a possible early
 921     // exit). Otherwise there would be extra Phi involved between the
 922     // loop's Phi and the store.
 923     // - there must be no early exit from the loop before the Store
 924     // (such an exit most of the time would be an extra use of the
 925     // memory Phi but sometimes is a bottom memory Phi that takes the
 926     // store as input).
 927 
 928     if (!n_loop->is_member(address_loop) &&
 929         !n_loop->is_member(value_loop) &&
 930         mem->is_Phi() && mem->in(0) == n_loop->_head &&
 931         mem->outcnt() == 1 &&
 932         mem->in(LoopNode::LoopBackControl) == n) {
 933 
 934       assert(n_loop->_tail != nullptr, "need a tail");
 935       assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
 936 
 937       // Verify that there's no early exit of the loop before the store.
 938       bool ctrl_ok = false;
 939       {
 940         // Follow control from loop head until n, we exit the loop or
 941         // we reach the tail
 942         ResourceMark rm;
 943         Unique_Node_List wq;
 944         wq.push(n_loop->_head);
 945 
 946         for (uint next = 0; next < wq.size(); ++next) {
 947           Node *m = wq.at(next);
 948           if (m == n->in(0)) {
 949             ctrl_ok = true;
 950             continue;
 951           }
 952           assert(!has_ctrl(m), "should be CFG");
 953           if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
 954             ctrl_ok = false;
 955             break;
 956           }
 957           enqueue_cfg_uses(m, wq);
 958           if (wq.size() > 10) {
 959             ctrl_ok = false;
 960             break;
 961           }
 962         }
 963       }
 964       if (ctrl_ok) {
 965         // move the Store
 966         _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
 967         _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
 968         _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
 969         // Disconnect the phi now. An empty phi can confuse other
 970         // optimizations in this pass of loop opts.
 971         _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
 972         n_loop->_body.yank(mem);
 973 
 974         set_ctrl_and_loop(n, n->in(0));
 975 
 976         return n;
 977       }
 978     }
 979   }
 980   return nullptr;
 981 }
 982 
 983 // Try moving a store out of a loop, right after the loop
 984 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
 985   if (n->is_Store() && n->in(0) != nullptr) {
 986     Node *n_ctrl = get_ctrl(n);
 987     IdealLoopTree *n_loop = get_loop(n_ctrl);
 988     // Store must be in a loop
 989     if (n_loop != _ltree_root && !n_loop->_irreducible) {
 990       Node* address = n->in(MemNode::Address);
 991       Node* value = n->in(MemNode::ValueIn);
 992       IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 993       // address must be loop invariant
 994       if (!n_loop->is_member(address_loop)) {
 995         // Store must be last on this memory slice in the loop and
 996         // nothing in the loop must observe it
 997         Node* phi = nullptr;
 998         for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 999           Node* u = n->fast_out(i);
1000           if (has_ctrl(u)) { // control use?
1001             IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1002             if (!n_loop->is_member(u_loop)) {
1003               continue;
1004             }
1005             if (u->is_Phi() && u->in(0) == n_loop->_head) {
1006               assert(_igvn.type(u) == Type::MEMORY, "bad phi");
1007               // multiple phis on the same slice are possible
1008               if (phi != nullptr) {
1009                 return;
1010               }
1011               phi = u;
1012               continue;
1013             }
1014           }
1015           return;
1016         }
1017         if (phi != nullptr) {
1018           // Nothing in the loop before the store (next iteration)
1019           // must observe the stored value
1020           bool mem_ok = true;
1021           {
1022             ResourceMark rm;
1023             Unique_Node_List wq;
1024             wq.push(phi);
1025             for (uint next = 0; next < wq.size() && mem_ok; ++next) {
1026               Node *m = wq.at(next);
1027               for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
1028                 Node* u = m->fast_out(i);
1029                 if (u->is_Store() || u->is_Phi()) {
1030                   if (u != n) {
1031                     wq.push(u);
1032                     mem_ok = (wq.size() <= 10);
1033                   }
1034                 } else {
1035                   mem_ok = false;
1036                   break;
1037                 }
1038               }
1039             }
1040           }
1041           if (mem_ok) {
1042             // Move the store out of the loop if the LCA of all
1043             // users (except for the phi) is outside the loop.
1044             Node* hook = new Node(1);
1045             hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
1046             _igvn.rehash_node_delayed(phi);
1047             int count = phi->replace_edge(n, hook, &_igvn);
1048             assert(count > 0, "inconsistent phi");
1049 
1050             // Compute latest point this store can go
1051             Node* lca = get_late_ctrl(n, get_ctrl(n));
1052             if (lca->is_OuterStripMinedLoop()) {
1053               lca = lca->in(LoopNode::EntryControl);
1054             }
1055             if (n_loop->is_member(get_loop(lca))) {
1056               // LCA is in the loop - bail out
1057               _igvn.replace_node(hook, n);
1058               return;
1059             }
1060 #ifdef ASSERT
1061             if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
1062               assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
1063               n_loop->_head->as_Loop()->verify_strip_mined(1);
1064               Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
1065               IdealLoopTree* outer_loop = get_loop(outer);
1066               assert(n_loop->_parent == outer_loop, "broken loop tree");
1067               assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
1068             }
1069 #endif
1070             lca = place_outside_loop(lca, n_loop);
1071             assert(!n_loop->is_member(get_loop(lca)), "control must not be back in the loop");
1072             assert(get_loop(lca)->_nest < n_loop->_nest || get_loop(lca)->_head->as_Loop()->is_in_infinite_subgraph(), "must not be moved into inner loop");
1073 
1074             // Move store out of the loop
1075             _igvn.replace_node(hook, n->in(MemNode::Memory));
1076             _igvn.replace_input_of(n, 0, lca);
1077             set_ctrl_and_loop(n, lca);
1078 
1079             // Disconnect the phi now. An empty phi can confuse other
1080             // optimizations in this pass of loop opts..
1081             if (phi->in(LoopNode::LoopBackControl) == phi) {
1082               _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
1083               n_loop->_body.yank(phi);
1084             }
1085           }
1086         }
1087       }
1088     }
1089   }
1090 }
1091 
1092 //------------------------------split_if_with_blocks_pre-----------------------
1093 // Do the real work in a non-recursive function.  Data nodes want to be
1094 // cloned in the pre-order so they can feed each other nicely.
1095 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
1096   // Cloning these guys is unlikely to win
1097   int n_op = n->Opcode();
1098   if (n_op == Op_MergeMem) {
1099     return n;
1100   }
1101   if (n->is_Proj()) {
1102     return n;
1103   }
1104   // Do not clone-up CmpFXXX variations, as these are always
1105   // followed by a CmpI
1106   if (n->is_Cmp()) {
1107     return n;
1108   }
1109   // Attempt to use a conditional move instead of a phi/branch
1110   if (ConditionalMoveLimit > 0 && n_op == Op_Region) {
1111     Node *cmov = conditional_move( n );
1112     if (cmov) {
1113       return cmov;
1114     }
1115   }
1116   if (n->is_CFG() || n->is_LoadStore()) {
1117     return n;
1118   }
1119   if (n->is_Opaque1()) { // Opaque nodes cannot be mod'd
1120     if (!C->major_progress()) {   // If chance of no more loop opts...
1121       _igvn._worklist.push(n);  // maybe we'll remove them
1122     }
1123     return n;
1124   }
1125 
1126   if (n->is_Con()) {
1127     return n;   // No cloning for Con nodes
1128   }
1129 
1130   Node *n_ctrl = get_ctrl(n);
1131   if (!n_ctrl) {
1132     return n;       // Dead node
1133   }
1134 
1135   Node* res = try_move_store_before_loop(n, n_ctrl);
1136   if (res != nullptr) {
1137     return n;
1138   }
1139 
1140   // Attempt to remix address expressions for loop invariants
1141   Node *m = remix_address_expressions( n );
1142   if( m ) return m;
1143 
1144   if (n_op == Op_AddI) {
1145     Node *nn = convert_add_to_muladd( n );
1146     if ( nn ) return nn;
1147   }
1148 
1149   if (n->is_ConstraintCast()) {
1150     Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
1151     // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
1152     // Node control inputs don't necessarily agree with loop control info (due to
1153     // transformations happened in between), thus additional dominance check is needed
1154     // to keep loop info valid.
1155     if (dom_cast != nullptr && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1156       _igvn.replace_node(n, dom_cast);
1157       return dom_cast;
1158     }
1159   }
1160 
1161   // Determine if the Node has inputs from some local Phi.
1162   // Returns the block to clone thru.
1163   Node *n_blk = has_local_phi_input( n );
1164   if( !n_blk ) return n;
1165 
1166   // Do not clone the trip counter through on a CountedLoop
1167   // (messes up the canonical shape).
1168   if (((n_blk->is_CountedLoop() || (n_blk->is_Loop() && n_blk->as_Loop()->is_loop_nest_inner_loop())) && n->Opcode() == Op_AddI) ||
1169       (n_blk->is_LongCountedLoop() && n->Opcode() == Op_AddL)) {
1170     return n;
1171   }
1172   // Pushing a shift through the iv Phi can get in the way of addressing optimizations or range check elimination
1173   if (n_blk->is_BaseCountedLoop() && n->Opcode() == Op_LShift(n_blk->as_BaseCountedLoop()->bt()) &&
1174       n->in(1) == n_blk->as_BaseCountedLoop()->phi()) {
1175     return n;
1176   }
1177 
1178   // Check for having no control input; not pinned.  Allow
1179   // dominating control.
1180   if (n->in(0)) {
1181     Node *dom = idom(n_blk);
1182     if (dom_lca(n->in(0), dom) != n->in(0)) {
1183       return n;
1184     }
1185   }
1186   // Policy: when is it profitable.  You must get more wins than
1187   // policy before it is considered profitable.  Policy is usually 0,
1188   // so 1 win is considered profitable.  Big merges will require big
1189   // cloning, so get a larger policy.
1190   int policy = n_blk->req() >> 2;
1191 
1192   // If the loop is a candidate for range check elimination,
1193   // delay splitting through it's phi until a later loop optimization
1194   if (n_blk->is_BaseCountedLoop()) {
1195     IdealLoopTree *lp = get_loop(n_blk);
1196     if (lp && lp->_rce_candidate) {
1197       return n;
1198     }
1199   }
1200 
1201   if (must_throttle_split_if()) return n;
1202 
1203   // Split 'n' through the merge point if it is profitable
1204   Node *phi = split_thru_phi( n, n_blk, policy );
1205   if (!phi) return n;
1206 
1207   // Found a Phi to split thru!
1208   // Replace 'n' with the new phi
1209   _igvn.replace_node( n, phi );
1210   // Moved a load around the loop, 'en-registering' something.
1211   if (n_blk->is_Loop() && n->is_Load() &&
1212       !phi->in(LoopNode::LoopBackControl)->is_Load())
1213     C->set_major_progress();
1214 
1215   return phi;
1216 }
1217 
1218 static bool merge_point_too_heavy(Compile* C, Node* region) {
1219   // Bail out if the region and its phis have too many users.
1220   int weight = 0;
1221   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1222     weight += region->fast_out(i)->outcnt();
1223   }
1224   int nodes_left = C->max_node_limit() - C->live_nodes();
1225   if (weight * 8 > nodes_left) {
1226     if (PrintOpto) {
1227       tty->print_cr("*** Split-if bails out:  %d nodes, region weight %d", C->unique(), weight);
1228     }
1229     return true;
1230   } else {
1231     return false;
1232   }
1233 }
1234 
1235 static bool merge_point_safe(Node* region) {
1236   // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1237   // having a PhiNode input. This sidesteps the dangerous case where the split
1238   // ConvI2LNode may become TOP if the input Value() does not
1239   // overlap the ConvI2L range, leaving a node which may not dominate its
1240   // uses.
1241   // A better fix for this problem can be found in the BugTraq entry, but
1242   // expediency for Mantis demands this hack.
1243 #ifdef _LP64
1244   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1245     Node* n = region->fast_out(i);
1246     if (n->is_Phi()) {
1247       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1248         Node* m = n->fast_out(j);
1249         if (m->Opcode() == Op_ConvI2L)
1250           return false;
1251         if (m->is_CastII()) {
1252           return false;
1253         }
1254       }
1255     }
1256   }
1257 #endif
1258   return true;
1259 }
1260 
1261 
1262 //------------------------------place_outside_loop---------------------------------
1263 // Place some computation outside of this loop on the path to the use passed as argument
1264 Node* PhaseIdealLoop::place_outside_loop(Node* useblock, IdealLoopTree* loop) const {
1265   Node* head = loop->_head;
1266   assert(!loop->is_member(get_loop(useblock)), "must be outside loop");
1267   if (head->is_Loop() && head->as_Loop()->is_strip_mined()) {
1268     loop = loop->_parent;
1269     assert(loop->_head->is_OuterStripMinedLoop(), "malformed strip mined loop");
1270   }
1271 
1272   // Pick control right outside the loop
1273   for (;;) {
1274     Node* dom = idom(useblock);
1275     if (loop->is_member(get_loop(dom))) {
1276       break;
1277     }
1278     useblock = dom;
1279   }
1280   assert(find_non_split_ctrl(useblock) == useblock, "should be non split control");
1281   return useblock;
1282 }
1283 
1284 
1285 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1286   if (!n->is_If() || n->is_BaseCountedLoopEnd()) {
1287     return false;
1288   }
1289   if (!n->in(0)->is_Region()) {
1290     return false;
1291   }
1292 
1293   Node* region = n->in(0);
1294   Node* dom = idom(region);
1295   if (!dom->is_If() ||  !n->as_If()->same_condition(dom, &_igvn)) {
1296     return false;
1297   }
1298   IfNode* dom_if = dom->as_If();
1299   Node* proj_true = dom_if->proj_out(1);
1300   Node* proj_false = dom_if->proj_out(0);
1301 
1302   for (uint i = 1; i < region->req(); i++) {
1303     if (is_dominator(proj_true, region->in(i))) {
1304       continue;
1305     }
1306     if (is_dominator(proj_false, region->in(i))) {
1307       continue;
1308     }
1309     return false;
1310   }
1311 
1312   return true;
1313 }
1314 
1315 
1316 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1317   if (must_throttle_split_if()) {
1318     return false;
1319   }
1320 
1321   // Do not do 'split-if' if irreducible loops are present.
1322   if (_has_irreducible_loops) {
1323     return false;
1324   }
1325 
1326   if (merge_point_too_heavy(C, n_ctrl)) {
1327     return false;
1328   }
1329 
1330   // Do not do 'split-if' if some paths are dead.  First do dead code
1331   // elimination and then see if its still profitable.
1332   for (uint i = 1; i < n_ctrl->req(); i++) {
1333     if (n_ctrl->in(i) == C->top()) {
1334       return false;
1335     }
1336   }
1337 
1338   // If trying to do a 'Split-If' at the loop head, it is only
1339   // profitable if the cmp folds up on BOTH paths.  Otherwise we
1340   // risk peeling a loop forever.
1341 
1342   // CNC - Disabled for now.  Requires careful handling of loop
1343   // body selection for the cloned code.  Also, make sure we check
1344   // for any input path not being in the same loop as n_ctrl.  For
1345   // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1346   // because the alternative loop entry points won't be converted
1347   // into LoopNodes.
1348   IdealLoopTree *n_loop = get_loop(n_ctrl);
1349   for (uint j = 1; j < n_ctrl->req(); j++) {
1350     if (get_loop(n_ctrl->in(j)) != n_loop) {
1351       return false;
1352     }
1353   }
1354 
1355   // Check for safety of the merge point.
1356   if (!merge_point_safe(n_ctrl)) {
1357     return false;
1358   }
1359 
1360   return true;
1361 }
1362 
1363 // Detect if the node is the inner strip-mined loop
1364 // Return: null if it's not the case, or the exit of outer strip-mined loop
1365 static Node* is_inner_of_stripmined_loop(const Node* out) {
1366   Node* out_le = nullptr;
1367 
1368   if (out->is_CountedLoopEnd()) {
1369       const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1370 
1371       if (loop != nullptr && loop->is_strip_mined()) {
1372         out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1373       }
1374   }
1375 
1376   return out_le;
1377 }
1378 
1379 //------------------------------split_if_with_blocks_post----------------------
1380 // Do the real work in a non-recursive function.  CFG hackery wants to be
1381 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1382 // info.
1383 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1384 
1385   // Cloning Cmp through Phi's involves the split-if transform.
1386   // FastLock is not used by an If
1387   if (n->is_Cmp() && !n->is_FastLock()) {
1388     Node *n_ctrl = get_ctrl(n);
1389     // Determine if the Node has inputs from some local Phi.
1390     // Returns the block to clone thru.
1391     Node *n_blk = has_local_phi_input(n);
1392     if (n_blk != n_ctrl) {
1393       return;
1394     }
1395 
1396     if (!can_split_if(n_ctrl)) {
1397       return;
1398     }
1399 
1400     if (n->outcnt() != 1) {
1401       return; // Multiple bool's from 1 compare?
1402     }
1403     Node *bol = n->unique_out();
1404     assert(bol->is_Bool(), "expect a bool here");
1405     if (bol->outcnt() != 1) {
1406       return;// Multiple branches from 1 compare?
1407     }
1408     Node *iff = bol->unique_out();
1409 
1410     // Check some safety conditions
1411     if (iff->is_If()) {        // Classic split-if?
1412       if (iff->in(0) != n_ctrl) {
1413         return; // Compare must be in same blk as if
1414       }
1415     } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1416       // Can't split CMove with different control.
1417       if (get_ctrl(iff) != n_ctrl) {
1418         return;
1419       }
1420       if (get_ctrl(iff->in(2)) == n_ctrl ||
1421           get_ctrl(iff->in(3)) == n_ctrl) {
1422         return;                 // Inputs not yet split-up
1423       }
1424       if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1425         return;                 // Loop-invar test gates loop-varying CMOVE
1426       }
1427     } else {
1428       return;  // some other kind of node, such as an Allocate
1429     }
1430 
1431     // When is split-if profitable?  Every 'win' on means some control flow
1432     // goes dead, so it's almost always a win.
1433     int policy = 0;
1434     // Split compare 'n' through the merge point if it is profitable
1435     Node *phi = split_thru_phi( n, n_ctrl, policy);
1436     if (!phi) {
1437       return;
1438     }
1439 
1440     // Found a Phi to split thru!
1441     // Replace 'n' with the new phi
1442     _igvn.replace_node(n, phi);
1443 
1444     // Now split the bool up thru the phi
1445     Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1446     guarantee(bolphi != nullptr, "null boolean phi node");
1447 
1448     _igvn.replace_node(bol, bolphi);
1449     assert(iff->in(1) == bolphi, "");
1450 
1451     if (bolphi->Value(&_igvn)->singleton()) {
1452       return;
1453     }
1454 
1455     // Conditional-move?  Must split up now
1456     if (!iff->is_If()) {
1457       Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1458       _igvn.replace_node(iff, cmovphi);
1459       return;
1460     }
1461 
1462     // Now split the IF
1463     C->print_method(PHASE_BEFORE_SPLIT_IF, 4, iff);
1464     if (TraceLoopOpts) {
1465       tty->print_cr("Split-If");
1466     }
1467     do_split_if(iff);
1468     C->print_method(PHASE_AFTER_SPLIT_IF, 4, iff);
1469     return;
1470   }
1471 
1472   // Two identical ifs back to back can be merged
1473   if (try_merge_identical_ifs(n)) {
1474     return;
1475   }
1476 
1477   // Check for an IF ready to split; one that has its
1478   // condition codes input coming from a Phi at the block start.
1479   int n_op = n->Opcode();
1480 
1481   // Check for an IF being dominated by another IF same test
1482   if (n_op == Op_If ||
1483       n_op == Op_RangeCheck) {
1484     Node *bol = n->in(1);
1485     uint max = bol->outcnt();
1486     // Check for same test used more than once?
1487     if (bol->is_Bool() && (max > 1 || bol->in(1)->is_SubTypeCheck())) {
1488       // Search up IDOMs to see if this IF is dominated.
1489       Node* cmp = bol->in(1);
1490       Node *cutoff = cmp->is_SubTypeCheck() ? dom_lca(get_ctrl(cmp->in(1)), get_ctrl(cmp->in(2))) : get_ctrl(bol);
1491 
1492       // Now search up IDOMs till cutoff, looking for a dominating test
1493       Node *prevdom = n;
1494       Node *dom = idom(prevdom);
1495       while (dom != cutoff) {
1496         if (dom->req() > 1 && n->as_If()->same_condition(dom, &_igvn) && prevdom->in(0) == dom &&
1497             safe_for_if_replacement(dom)) {
1498           // It's invalid to move control dependent data nodes in the inner
1499           // strip-mined loop, because:
1500           //  1) break validation of LoopNode::verify_strip_mined()
1501           //  2) move code with side-effect in strip-mined loop
1502           // Move to the exit of outer strip-mined loop in that case.
1503           Node* out_le = is_inner_of_stripmined_loop(dom);
1504           if (out_le != nullptr) {
1505             prevdom = out_le;
1506           }
1507           // Replace the dominated test with an obvious true or false.
1508           // Place it on the IGVN worklist for later cleanup.
1509           C->set_major_progress();
1510           // Split if: pin array accesses that are control dependent on a range check and moved to a regular if,
1511           // to prevent an array load from floating above its range check. There are three cases:
1512           // 1. Move from RangeCheck "a" to RangeCheck "b": don't need to pin. If we ever remove b, then we pin
1513           //    all its array accesses at that point.
1514           // 2. We move from RangeCheck "a" to regular if "b": need to pin. If we ever remove b, then its array
1515           //    accesses would start to float, since we don't pin at that point.
1516           // 3. If we move from regular if: don't pin. All array accesses are already assumed to be pinned.
1517           bool pin_array_access_nodes =  n->Opcode() == Op_RangeCheck &&
1518                                          prevdom->in(0)->Opcode() != Op_RangeCheck;
1519           dominated_by(prevdom->as_IfProj(), n->as_If(), false, pin_array_access_nodes);
1520           DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
1521           return;
1522         }
1523         prevdom = dom;
1524         dom = idom(prevdom);
1525       }
1526     }
1527   }
1528 
1529   try_sink_out_of_loop(n);
1530   if (C->failing()) {
1531     return;
1532   }
1533 
1534   try_move_store_after_loop(n);
1535 }
1536 
1537 // Transform:
1538 //
1539 // if (some_condition) {
1540 //   // body 1
1541 // } else {
1542 //   // body 2
1543 // }
1544 // if (some_condition) {
1545 //   // body 3
1546 // } else {
1547 //   // body 4
1548 // }
1549 //
1550 // into:
1551 //
1552 //
1553 // if (some_condition) {
1554 //   // body 1
1555 //   // body 3
1556 // } else {
1557 //   // body 2
1558 //   // body 4
1559 // }
1560 bool PhaseIdealLoop::try_merge_identical_ifs(Node* n) {
1561   if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1562     Node *n_ctrl = n->in(0);
1563     IfNode* dom_if = idom(n_ctrl)->as_If();
1564     if (n->in(1) != dom_if->in(1)) {
1565       assert(n->in(1)->in(1)->is_SubTypeCheck() &&
1566              (n->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr ||
1567               dom_if->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr), "only for subtype checks with profile data attached");
1568       _igvn.replace_input_of(n, 1, dom_if->in(1));
1569     }
1570     ProjNode* dom_proj_true = dom_if->proj_out(1);
1571     ProjNode* dom_proj_false = dom_if->proj_out(0);
1572 
1573     // Now split the IF
1574     RegionNode* new_false_region;
1575     RegionNode* new_true_region;
1576     do_split_if(n, &new_false_region, &new_true_region);
1577     assert(new_false_region->req() == new_true_region->req(), "");
1578 #ifdef ASSERT
1579     for (uint i = 1; i < new_false_region->req(); ++i) {
1580       assert(new_false_region->in(i)->in(0) == new_true_region->in(i)->in(0), "unexpected shape following split if");
1581       assert(i == new_false_region->req() - 1 || new_false_region->in(i)->in(0)->in(1) == new_false_region->in(i + 1)->in(0)->in(1), "unexpected shape following split if");
1582     }
1583 #endif
1584     assert(new_false_region->in(1)->in(0)->in(1) == dom_if->in(1), "dominating if and dominated if after split must share test");
1585 
1586     // We now have:
1587     // if (some_condition) {
1588     //   // body 1
1589     //   if (some_condition) {
1590     //     body3: // new_true_region
1591     //     // body3
1592     //   } else {
1593     //     goto body4;
1594     //   }
1595     // } else {
1596     //   // body 2
1597     //  if (some_condition) {
1598     //     goto body3;
1599     //   } else {
1600     //     body4:   // new_false_region
1601     //     // body4;
1602     //   }
1603     // }
1604     //
1605 
1606     // clone pinned nodes thru the resulting regions
1607     push_pinned_nodes_thru_region(dom_if, new_true_region);
1608     push_pinned_nodes_thru_region(dom_if, new_false_region);
1609 
1610     // Optimize out the cloned ifs. Because pinned nodes were cloned, this also allows a CastPP that would be dependent
1611     // on a projection of n to have the dom_if as a control dependency. We don't want the CastPP to end up with an
1612     // unrelated control dependency.
1613     for (uint i = 1; i < new_false_region->req(); i++) {
1614       if (is_dominator(dom_proj_true, new_false_region->in(i))) {
1615         dominated_by(dom_proj_true->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1616       } else {
1617         assert(is_dominator(dom_proj_false, new_false_region->in(i)), "bad if");
1618         dominated_by(dom_proj_false->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1619       }
1620     }
1621     return true;
1622   }
1623   return false;
1624 }
1625 
1626 void PhaseIdealLoop::push_pinned_nodes_thru_region(IfNode* dom_if, Node* region) {
1627   for (DUIterator i = region->outs(); region->has_out(i); i++) {
1628     Node* u = region->out(i);
1629     if (!has_ctrl(u) || u->is_Phi() || !u->depends_only_on_test() || !_igvn.no_dependent_zero_check(u)) {
1630       continue;
1631     }
1632     assert(u->in(0) == region, "not a control dependent node?");
1633     uint j = 1;
1634     for (; j < u->req(); ++j) {
1635       Node* in = u->in(j);
1636       if (!is_dominator(ctrl_or_self(in), dom_if)) {
1637         break;
1638       }
1639     }
1640     if (j == u->req()) {
1641       Node *phi = PhiNode::make_blank(region, u);
1642       for (uint k = 1; k < region->req(); ++k) {
1643         Node* clone = u->clone();
1644         clone->set_req(0, region->in(k));
1645         register_new_node(clone, region->in(k));
1646         phi->init_req(k, clone);
1647       }
1648       register_new_node(phi, region);
1649       _igvn.replace_node(u, phi);
1650       --i;
1651     }
1652   }
1653 }
1654 
1655 bool PhaseIdealLoop::safe_for_if_replacement(const Node* dom) const {
1656   if (!dom->is_CountedLoopEnd()) {
1657     return true;
1658   }
1659   CountedLoopEndNode* le = dom->as_CountedLoopEnd();
1660   CountedLoopNode* cl = le->loopnode();
1661   if (cl == nullptr) {
1662     return true;
1663   }
1664   if (!cl->is_main_loop()) {
1665     return true;
1666   }
1667   if (cl->is_canonical_loop_entry() == nullptr) {
1668     return true;
1669   }
1670   // Further unrolling is possible so loop exit condition might change
1671   return false;
1672 }
1673 
1674 // See if a shared loop-varying computation has no loop-varying uses.
1675 // Happens if something is only used for JVM state in uncommon trap exits,
1676 // like various versions of induction variable+offset.  Clone the
1677 // computation per usage to allow it to sink out of the loop.
1678 void PhaseIdealLoop::try_sink_out_of_loop(Node* n) {
1679   if (has_ctrl(n) &&
1680       !n->is_Phi() &&
1681       !n->is_Bool() &&
1682       !n->is_Proj() &&
1683       !n->is_MergeMem() &&
1684       !n->is_CMove() &&
1685       !n->is_OpaqueNotNull() &&
1686       !n->is_OpaqueInitializedAssertionPredicate() &&
1687       !n->is_OpaqueTemplateAssertionPredicate() &&
1688       !n->is_Type()) {
1689     Node *n_ctrl = get_ctrl(n);
1690     IdealLoopTree *n_loop = get_loop(n_ctrl);
1691 
1692     if (n->in(0) != nullptr) {
1693       IdealLoopTree* loop_ctrl = get_loop(n->in(0));
1694       if (n_loop != loop_ctrl && n_loop->is_member(loop_ctrl)) {
1695         // n has a control input inside a loop but get_ctrl() is member of an outer loop. This could happen, for example,
1696         // for Div nodes inside a loop (control input inside loop) without a use except for an UCT (outside the loop).
1697         // Rewire control of n to right outside of the loop, regardless if its input(s) are later sunk or not.
1698         Node* maybe_pinned_n = n;
1699         Node* outside_ctrl = place_outside_loop(n_ctrl, loop_ctrl);
1700         if (n->depends_only_on_test()) {
1701           Node* pinned_clone = n->pin_array_access_node();
1702           if (pinned_clone != nullptr) {
1703             // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1704             // range check for that access. If that condition is replaced by an identical dominating one, then an
1705             // unpinned load would risk floating above its range check.
1706             register_new_node(pinned_clone, n_ctrl);
1707             maybe_pinned_n = pinned_clone;
1708             _igvn.replace_node(n, pinned_clone);
1709           }
1710         }
1711         _igvn.replace_input_of(maybe_pinned_n, 0, outside_ctrl);
1712       }
1713     }
1714     if (n_loop != _ltree_root && n->outcnt() > 1) {
1715       // Compute early control: needed for anti-dependence analysis. It's also possible that as a result of
1716       // previous transformations in this loop opts round, the node can be hoisted now: early control will tell us.
1717       Node* early_ctrl = compute_early_ctrl(n, n_ctrl);
1718       if (n_loop->is_member(get_loop(early_ctrl)) && // check that this one can't be hoisted now
1719           ctrl_of_all_uses_out_of_loop(n, early_ctrl, n_loop)) { // All uses in outer loops!
1720         if (n->is_Store() || n->is_LoadStore()) {
1721             assert(false, "no node with a side effect");
1722             C->record_failure("no node with a side effect");
1723             return;
1724         }
1725         Node* outer_loop_clone = nullptr;
1726         for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin;) {
1727           Node* u = n->last_out(j); // Clone private computation per use
1728           _igvn.rehash_node_delayed(u);
1729           Node* x = nullptr;
1730           if (n->depends_only_on_test()) {
1731             // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1732             // range check for that access. If that condition is replaced by an identical dominating one, then an
1733             // unpinned load would risk floating above its range check.
1734             x = n->pin_array_access_node();
1735           }
1736           if (x == nullptr) {
1737             x = n->clone();
1738           }
1739           Node* x_ctrl = nullptr;
1740           if (u->is_Phi()) {
1741             // Replace all uses of normal nodes.  Replace Phi uses
1742             // individually, so the separate Nodes can sink down
1743             // different paths.
1744             uint k = 1;
1745             while (u->in(k) != n) k++;
1746             u->set_req(k, x);
1747             // x goes next to Phi input path
1748             x_ctrl = u->in(0)->in(k);
1749             // Find control for 'x' next to use but not inside inner loops.
1750             x_ctrl = place_outside_loop(x_ctrl, n_loop);
1751             --j;
1752           } else {              // Normal use
1753             if (has_ctrl(u)) {
1754               x_ctrl = get_ctrl(u);
1755             } else {
1756               x_ctrl = u->in(0);
1757             }
1758             // Find control for 'x' next to use but not inside inner loops.
1759             x_ctrl = place_outside_loop(x_ctrl, n_loop);
1760             // Replace all uses
1761             if (u->is_ConstraintCast() && _igvn.type(n)->higher_equal(u->bottom_type()) && u->in(0) == x_ctrl) {
1762               // If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary
1763               // anymore now that we're going to pin n as well
1764               _igvn.replace_node(u, x);
1765               --j;
1766             } else {
1767               int nb = u->replace_edge(n, x, &_igvn);
1768               j -= nb;
1769             }
1770           }
1771 
1772           if (n->is_Load()) {
1773             // For loads, add a control edge to a CFG node outside of the loop
1774             // to force them to not combine and return back inside the loop
1775             // during GVN optimization (4641526).
1776             assert(x_ctrl == get_late_ctrl_with_anti_dep(x->as_Load(), early_ctrl, x_ctrl), "anti-dependences were already checked");
1777 
1778             IdealLoopTree* x_loop = get_loop(x_ctrl);
1779             Node* x_head = x_loop->_head;
1780             if (x_head->is_Loop() && x_head->is_OuterStripMinedLoop()) {
1781               // Do not add duplicate LoadNodes to the outer strip mined loop
1782               if (outer_loop_clone != nullptr) {
1783                 _igvn.replace_node(x, outer_loop_clone);
1784                 continue;
1785               }
1786               outer_loop_clone = x;
1787             }
1788             x->set_req(0, x_ctrl);
1789           } else if (n->in(0) != nullptr){
1790             x->set_req(0, x_ctrl);
1791           }
1792           assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1793           assert(!n_loop->is_member(get_loop(x_ctrl)), "should have moved out of loop");
1794           register_new_node(x, x_ctrl);
1795 
1796           // Chain of AddP nodes: (AddP base (AddP base (AddP base )))
1797           // All AddP nodes must keep the same base after sinking so:
1798           // 1- We don't add a CastPP here until the last one of the chain is sunk: if part of the chain is not sunk,
1799           // their bases remain the same.
1800           // (see 2- below)
1801           assert(!x->is_AddP() || !x->in(AddPNode::Address)->is_AddP() ||
1802                  x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base) ||
1803                  !x->in(AddPNode::Address)->in(AddPNode::Base)->eqv_uncast(x->in(AddPNode::Base)), "unexpected AddP shape");
1804           if (x->in(0) == nullptr && !x->is_DecodeNarrowPtr() &&
1805               !(x->is_AddP() && x->in(AddPNode::Address)->is_AddP() && x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base))) {
1806             assert(!x->is_Load(), "load should be pinned");
1807             // Use a cast node to pin clone out of loop
1808             Node* cast = nullptr;
1809             for (uint k = 0; k < x->req(); k++) {
1810               Node* in = x->in(k);
1811               if (in != nullptr && n_loop->is_member(get_loop(get_ctrl(in)))) {
1812                 const Type* in_t = _igvn.type(in);
1813                 cast = ConstraintCastNode::make_cast_for_type(x_ctrl, in, in_t,
1814                                                               ConstraintCastNode::UnconditionalDependency, nullptr);
1815               }
1816               if (cast != nullptr) {
1817                 Node* prev = _igvn.hash_find_insert(cast);
1818                 if (prev != nullptr && get_ctrl(prev) == x_ctrl) {
1819                   cast->destruct(&_igvn);
1820                   cast = prev;
1821                 } else {
1822                   register_new_node(cast, x_ctrl);
1823                 }
1824                 x->replace_edge(in, cast);
1825                 // Chain of AddP nodes:
1826                 // 2- A CastPP of the base is only added now that all AddP nodes are sunk
1827                 if (x->is_AddP() && k == AddPNode::Base) {
1828                   update_addp_chain_base(x, n->in(AddPNode::Base), cast);
1829                 }
1830                 break;
1831               }
1832             }
1833             assert(cast != nullptr, "must have added a cast to pin the node");
1834           }
1835         }
1836         _igvn.remove_dead_node(n);
1837       }
1838       _dom_lca_tags_round = 0;
1839     }
1840   }
1841 }
1842 
1843 void PhaseIdealLoop::update_addp_chain_base(Node* x, Node* old_base, Node* new_base) {
1844   ResourceMark rm;
1845   Node_List wq;
1846   wq.push(x);
1847   while (wq.size() != 0) {
1848     Node* n = wq.pop();
1849     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1850       Node* u = n->fast_out(i);
1851       if (u->is_AddP() && u->in(AddPNode::Base) == old_base) {
1852         _igvn.replace_input_of(u, AddPNode::Base, new_base);
1853         wq.push(u);
1854       }
1855     }
1856   }
1857 }
1858 
1859 // Compute the early control of a node by following its inputs until we reach
1860 // nodes that are pinned. Then compute the LCA of the control of all pinned nodes.
1861 Node* PhaseIdealLoop::compute_early_ctrl(Node* n, Node* n_ctrl) {
1862   Node* early_ctrl = nullptr;
1863   ResourceMark rm;
1864   Unique_Node_List wq;
1865   wq.push(n);
1866   for (uint i = 0; i < wq.size(); i++) {
1867     Node* m = wq.at(i);
1868     Node* c = nullptr;
1869     if (m->is_CFG()) {
1870       c = m;
1871     } else if (m->pinned()) {
1872       c = m->in(0);
1873     } else {
1874       for (uint j = 0; j < m->req(); j++) {
1875         Node* in = m->in(j);
1876         if (in != nullptr) {
1877           wq.push(in);
1878         }
1879       }
1880     }
1881     if (c != nullptr) {
1882       assert(is_dominator(c, n_ctrl), "control input must dominate current control");
1883       if (early_ctrl == nullptr || is_dominator(early_ctrl, c)) {
1884         early_ctrl = c;
1885       }
1886     }
1887   }
1888   assert(is_dominator(early_ctrl, n_ctrl), "early control must dominate current control");
1889   return early_ctrl;
1890 }
1891 
1892 bool PhaseIdealLoop::ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop) {
1893   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1894     Node* u = n->fast_out(i);
1895     if (u->is_Opaque1()) {
1896       return false;  // Found loop limit, bugfix for 4677003
1897     }
1898     // We can't reuse tags in PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal() so make sure calls to
1899     // get_late_ctrl_with_anti_dep() use their own tag
1900     _dom_lca_tags_round++;
1901     assert(_dom_lca_tags_round != 0, "shouldn't wrap around");
1902 
1903     if (u->is_Phi()) {
1904       for (uint j = 1; j < u->req(); ++j) {
1905         if (u->in(j) == n && !ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, u->in(0)->in(j))) {
1906           return false;
1907         }
1908       }
1909     } else {
1910       Node* ctrl = has_ctrl(u) ? get_ctrl(u) : u->in(0);
1911       if (!ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, ctrl)) {
1912         return false;
1913       }
1914     }
1915   }
1916   return true;
1917 }
1918 
1919 bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl) {
1920   if (n->is_Load()) {
1921     ctrl = get_late_ctrl_with_anti_dep(n->as_Load(), n_ctrl, ctrl);
1922   }
1923   IdealLoopTree *u_loop = get_loop(ctrl);
1924   if (u_loop == n_loop) {
1925     return false; // Found loop-varying use
1926   }
1927   if (n_loop->is_member(u_loop)) {
1928     return false; // Found use in inner loop
1929   }
1930   // Sinking a node from a pre loop to its main loop pins the node between the pre and main loops. If that node is input
1931   // to a check that's eliminated by range check elimination, it becomes input to an expression that feeds into the exit
1932   // test of the pre loop above the point in the graph where it's pinned.
1933   if (n_loop->_head->is_CountedLoop() && n_loop->_head->as_CountedLoop()->is_pre_loop()) {
1934     CountedLoopNode* pre_loop = n_loop->_head->as_CountedLoop();
1935     if (is_dominator(pre_loop->loopexit(), ctrl)) {
1936       return false;
1937     }
1938   }
1939   return true;
1940 }
1941 
1942 //------------------------------split_if_with_blocks---------------------------
1943 // Check for aggressive application of 'split-if' optimization,
1944 // using basic block level info.
1945 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1946   Node* root = C->root();
1947   visited.set(root->_idx); // first, mark root as visited
1948   // Do pre-visit work for root
1949   Node* n   = split_if_with_blocks_pre(root);
1950   uint  cnt = n->outcnt();
1951   uint  i   = 0;
1952 
1953   while (true) {
1954     // Visit all children
1955     if (i < cnt) {
1956       Node* use = n->raw_out(i);
1957       ++i;
1958       if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1959         // Now do pre-visit work for this use
1960         use = split_if_with_blocks_pre(use);
1961         nstack.push(n, i); // Save parent and next use's index.
1962         n   = use;         // Process all children of current use.
1963         cnt = use->outcnt();
1964         i   = 0;
1965       }
1966     }
1967     else {
1968       // All of n's children have been processed, complete post-processing.
1969       if (cnt != 0 && !n->is_Con()) {
1970         assert(has_node(n), "no dead nodes");
1971         split_if_with_blocks_post(n);
1972         if (C->failing()) {
1973           return;
1974         }
1975       }
1976       if (must_throttle_split_if()) {
1977         nstack.clear();
1978       }
1979       if (nstack.is_empty()) {
1980         // Finished all nodes on stack.
1981         break;
1982       }
1983       // Get saved parent node and next use's index. Visit the rest of uses.
1984       n   = nstack.node();
1985       cnt = n->outcnt();
1986       i   = nstack.index();
1987       nstack.pop();
1988     }
1989   }
1990 }
1991 
1992 
1993 //=============================================================================
1994 //
1995 //                   C L O N E   A   L O O P   B O D Y
1996 //
1997 
1998 //------------------------------clone_iff--------------------------------------
1999 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2000 // "Nearly" because all Nodes have been cloned from the original in the loop,
2001 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
2002 // through the Phi recursively, and return a Bool.
2003 Node* PhaseIdealLoop::clone_iff(PhiNode* phi) {
2004 
2005   // Convert this Phi into a Phi merging Bools
2006   uint i;
2007   for (i = 1; i < phi->req(); i++) {
2008     Node* b = phi->in(i);
2009     if (b->is_Phi()) {
2010       _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi()));
2011     } else {
2012       assert(b->is_Bool() || b->is_OpaqueNotNull() || b->is_OpaqueInitializedAssertionPredicate(),
2013              "bool, non-null check with OpaqueNotNull or Initialized Assertion Predicate with its Opaque node");
2014     }
2015   }
2016   Node* n = phi->in(1);
2017   Node* sample_opaque = nullptr;
2018   Node *sample_bool = nullptr;
2019   if (n->is_OpaqueNotNull() || n->is_OpaqueInitializedAssertionPredicate()) {
2020     sample_opaque = n;
2021     sample_bool = n->in(1);
2022     assert(sample_bool->is_Bool(), "wrong type");
2023   } else {
2024     sample_bool = n;
2025   }
2026   Node *sample_cmp = sample_bool->in(1);
2027 
2028   // Make Phis to merge the Cmp's inputs.
2029   PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
2030   PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
2031   for (i = 1; i < phi->req(); i++) {
2032     Node *n1 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
2033     Node *n2 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
2034     phi1->set_req(i, n1);
2035     phi2->set_req(i, n2);
2036     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2037     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2038   }
2039   // See if these Phis have been made before.
2040   // Register with optimizer
2041   Node *hit1 = _igvn.hash_find_insert(phi1);
2042   if (hit1) {                   // Hit, toss just made Phi
2043     _igvn.remove_dead_node(phi1); // Remove new phi
2044     assert(hit1->is_Phi(), "" );
2045     phi1 = (PhiNode*)hit1;      // Use existing phi
2046   } else {                      // Miss
2047     _igvn.register_new_node_with_optimizer(phi1);
2048   }
2049   Node *hit2 = _igvn.hash_find_insert(phi2);
2050   if (hit2) {                   // Hit, toss just made Phi
2051     _igvn.remove_dead_node(phi2); // Remove new phi
2052     assert(hit2->is_Phi(), "" );
2053     phi2 = (PhiNode*)hit2;      // Use existing phi
2054   } else {                      // Miss
2055     _igvn.register_new_node_with_optimizer(phi2);
2056   }
2057   // Register Phis with loop/block info
2058   set_ctrl(phi1, phi->in(0));
2059   set_ctrl(phi2, phi->in(0));
2060   // Make a new Cmp
2061   Node *cmp = sample_cmp->clone();
2062   cmp->set_req(1, phi1);
2063   cmp->set_req(2, phi2);
2064   _igvn.register_new_node_with_optimizer(cmp);
2065   set_ctrl(cmp, phi->in(0));
2066 
2067   // Make a new Bool
2068   Node *b = sample_bool->clone();
2069   b->set_req(1,cmp);
2070   _igvn.register_new_node_with_optimizer(b);
2071   set_ctrl(b, phi->in(0));
2072 
2073   if (sample_opaque != nullptr) {
2074     Node* opaque = sample_opaque->clone();
2075     opaque->set_req(1, b);
2076     _igvn.register_new_node_with_optimizer(opaque);
2077     set_ctrl(opaque, phi->in(0));
2078     return opaque;
2079   }
2080 
2081   assert(b->is_Bool(), "");
2082   return b;
2083 }
2084 
2085 //------------------------------clone_bool-------------------------------------
2086 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2087 // "Nearly" because all Nodes have been cloned from the original in the loop,
2088 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
2089 // through the Phi recursively, and return a Bool.
2090 CmpNode*PhaseIdealLoop::clone_bool(PhiNode* phi) {
2091   uint i;
2092   // Convert this Phi into a Phi merging Bools
2093   for( i = 1; i < phi->req(); i++ ) {
2094     Node *b = phi->in(i);
2095     if( b->is_Phi() ) {
2096       _igvn.replace_input_of(phi, i, clone_bool(b->as_Phi()));
2097     } else {
2098       assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
2099     }
2100   }
2101 
2102   Node *sample_cmp = phi->in(1);
2103 
2104   // Make Phis to merge the Cmp's inputs.
2105   PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
2106   PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
2107   for( uint j = 1; j < phi->req(); j++ ) {
2108     Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
2109     Node *n1, *n2;
2110     if( cmp_top->is_Cmp() ) {
2111       n1 = cmp_top->in(1);
2112       n2 = cmp_top->in(2);
2113     } else {
2114       n1 = n2 = cmp_top;
2115     }
2116     phi1->set_req( j, n1 );
2117     phi2->set_req( j, n2 );
2118     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2119     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2120   }
2121 
2122   // See if these Phis have been made before.
2123   // Register with optimizer
2124   Node *hit1 = _igvn.hash_find_insert(phi1);
2125   if( hit1 ) {                  // Hit, toss just made Phi
2126     _igvn.remove_dead_node(phi1); // Remove new phi
2127     assert( hit1->is_Phi(), "" );
2128     phi1 = (PhiNode*)hit1;      // Use existing phi
2129   } else {                      // Miss
2130     _igvn.register_new_node_with_optimizer(phi1);
2131   }
2132   Node *hit2 = _igvn.hash_find_insert(phi2);
2133   if( hit2 ) {                  // Hit, toss just made Phi
2134     _igvn.remove_dead_node(phi2); // Remove new phi
2135     assert( hit2->is_Phi(), "" );
2136     phi2 = (PhiNode*)hit2;      // Use existing phi
2137   } else {                      // Miss
2138     _igvn.register_new_node_with_optimizer(phi2);
2139   }
2140   // Register Phis with loop/block info
2141   set_ctrl(phi1, phi->in(0));
2142   set_ctrl(phi2, phi->in(0));
2143   // Make a new Cmp
2144   Node *cmp = sample_cmp->clone();
2145   cmp->set_req( 1, phi1 );
2146   cmp->set_req( 2, phi2 );
2147   _igvn.register_new_node_with_optimizer(cmp);
2148   set_ctrl(cmp, phi->in(0));
2149 
2150   assert( cmp->is_Cmp(), "" );
2151   return (CmpNode*)cmp;
2152 }
2153 
2154 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
2155                                                  IdealLoopTree* loop, IdealLoopTree* outer_loop,
2156                                                  Node_List*& split_if_set, Node_List*& split_bool_set,
2157                                                  Node_List*& split_cex_set, Node_List& worklist,
2158                                                  uint new_counter, CloneLoopMode mode) {
2159   Node* nnn = old_new[old->_idx];
2160   // Copy uses to a worklist, so I can munge the def-use info
2161   // with impunity.
2162   for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2163     worklist.push(old->fast_out(j));
2164 
2165   while( worklist.size() ) {
2166     Node *use = worklist.pop();
2167     if (!has_node(use))  continue; // Ignore dead nodes
2168     if (use->in(0) == C->top())  continue;
2169     IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2170     // Check for data-use outside of loop - at least one of OLD or USE
2171     // must not be a CFG node.
2172 #ifdef ASSERT
2173     if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == nullptr) {
2174       Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
2175       assert(mode != IgnoreStripMined, "incorrect cloning mode");
2176       assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
2177     }
2178 #endif
2179     if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
2180 
2181       // If the Data use is an IF, that means we have an IF outside the
2182       // loop that is switching on a condition that is set inside the
2183       // loop.  Happens if people set a loop-exit flag; then test the flag
2184       // in the loop to break the loop, then test is again outside the
2185       // loop to determine which way the loop exited.
2186       //
2187       // For several uses we need to make sure that there is no phi between,
2188       // the use and the Bool/Cmp. We therefore clone the Bool/Cmp down here
2189       // to avoid such a phi in between.
2190       // For example, it is unexpected that there is a Phi between an
2191       // AllocateArray node and its ValidLengthTest input that could cause
2192       // split if to break.
2193       assert(!use->is_OpaqueTemplateAssertionPredicate(),
2194              "should not clone a Template Assertion Predicate which should be removed once it's useless");
2195       if (use->is_If() || use->is_CMove() || use->is_OpaqueNotNull() || use->is_OpaqueInitializedAssertionPredicate() ||
2196           (use->Opcode() == Op_AllocateArray && use->in(AllocateNode::ValidLengthTest) == old)) {
2197         // Since this code is highly unlikely, we lazily build the worklist
2198         // of such Nodes to go split.
2199         if (!split_if_set) {
2200           split_if_set = new Node_List();
2201         }
2202         split_if_set->push(use);
2203       }
2204       if (use->is_Bool()) {
2205         if (!split_bool_set) {
2206           split_bool_set = new Node_List();
2207         }
2208         split_bool_set->push(use);
2209       }
2210       if (use->Opcode() == Op_CreateEx) {
2211         if (!split_cex_set) {
2212           split_cex_set = new Node_List();
2213         }
2214         split_cex_set->push(use);
2215       }
2216 
2217 
2218       // Get "block" use is in
2219       uint idx = 0;
2220       while( use->in(idx) != old ) idx++;
2221       Node *prev = use->is_CFG() ? use : get_ctrl(use);
2222       assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
2223       Node* cfg = (prev->_idx >= new_counter && prev->is_Region())
2224         ? prev->in(2)
2225         : idom(prev);
2226       if( use->is_Phi() )     // Phi use is in prior block
2227         cfg = prev->in(idx);  // NOT in block of Phi itself
2228       if (cfg->is_top()) {    // Use is dead?
2229         _igvn.replace_input_of(use, idx, C->top());
2230         continue;
2231       }
2232 
2233       // If use is referenced through control edge... (idx == 0)
2234       if (mode == IgnoreStripMined && idx == 0) {
2235         LoopNode *head = loop->_head->as_Loop();
2236         if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
2237           // That node is outside the inner loop, leave it outside the
2238           // outer loop as well to not confuse verification code.
2239           assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
2240           _igvn.replace_input_of(use, 0, head->outer_loop_exit());
2241           continue;
2242         }
2243       }
2244 
2245       while(!outer_loop->is_member(get_loop(cfg))) {
2246         prev = cfg;
2247         cfg = (cfg->_idx >= new_counter && cfg->is_Region()) ? cfg->in(2) : idom(cfg);
2248       }
2249       // If the use occurs after merging several exits from the loop, then
2250       // old value must have dominated all those exits.  Since the same old
2251       // value was used on all those exits we did not need a Phi at this
2252       // merge point.  NOW we do need a Phi here.  Each loop exit value
2253       // is now merged with the peeled body exit; each exit gets its own
2254       // private Phi and those Phis need to be merged here.
2255       Node *phi;
2256       if( prev->is_Region() ) {
2257         if( idx == 0 ) {      // Updating control edge?
2258           phi = prev;         // Just use existing control
2259         } else {              // Else need a new Phi
2260           phi = PhiNode::make( prev, old );
2261           // Now recursively fix up the new uses of old!
2262           for( uint i = 1; i < prev->req(); i++ ) {
2263             worklist.push(phi); // Onto worklist once for each 'old' input
2264           }
2265         }
2266       } else {
2267         // Get new RegionNode merging old and new loop exits
2268         prev = old_new[prev->_idx];
2269         assert( prev, "just made this in step 7" );
2270         if( idx == 0) {      // Updating control edge?
2271           phi = prev;         // Just use existing control
2272         } else {              // Else need a new Phi
2273           // Make a new Phi merging data values properly
2274           phi = PhiNode::make( prev, old );
2275           phi->set_req( 1, nnn );
2276         }
2277       }
2278       // If inserting a new Phi, check for prior hits
2279       if( idx != 0 ) {
2280         Node *hit = _igvn.hash_find_insert(phi);
2281         if( hit == nullptr ) {
2282           _igvn.register_new_node_with_optimizer(phi); // Register new phi
2283         } else {                                      // or
2284           // Remove the new phi from the graph and use the hit
2285           _igvn.remove_dead_node(phi);
2286           phi = hit;                                  // Use existing phi
2287         }
2288         set_ctrl(phi, prev);
2289       }
2290       // Make 'use' use the Phi instead of the old loop body exit value
2291       assert(use->in(idx) == old, "old is still input of use");
2292       // We notify all uses of old, including use, and the indirect uses,
2293       // that may now be optimized because we have replaced old with phi.
2294       _igvn.add_users_to_worklist(old);
2295       if (idx == 0 &&
2296           use->depends_only_on_test()) {
2297         Node* pinned_clone = use->pin_array_access_node();
2298         if (pinned_clone != nullptr) {
2299           // Pin array access nodes: control is updated here to a region. If, after some transformations, only one path
2300           // into the region is left, an array load could become dependent on a condition that's not a range check for
2301           // that access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
2302           // floating above its range check.
2303           pinned_clone->set_req(0, phi);
2304           register_new_node_with_ctrl_of(pinned_clone, use);
2305           _igvn.replace_node(use, pinned_clone);
2306           continue;
2307         }
2308       }
2309       _igvn.replace_input_of(use, idx, phi);
2310       if( use->_idx >= new_counter ) { // If updating new phis
2311         // Not needed for correctness, but prevents a weak assert
2312         // in AddPNode from tripping (when we end up with different
2313         // base & derived Phis that will become the same after
2314         // IGVN does CSE).
2315         Node *hit = _igvn.hash_find_insert(use);
2316         if( hit )             // Go ahead and re-hash for hits.
2317           _igvn.replace_node( use, hit );
2318       }
2319     }
2320   }
2321 }
2322 
2323 static void collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
2324                                                                 const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
2325                                                                 bool check_old_new) {
2326   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2327     Node* u = n->fast_out(j);
2328     assert(check_old_new || old_new[u->_idx] == nullptr, "shouldn't have been cloned");
2329     if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == nullptr)) {
2330       Node* c = phase->get_ctrl(u);
2331       IdealLoopTree* u_loop = phase->get_loop(c);
2332       assert(!loop->is_member(u_loop) || !loop->_body.contains(u), "can be in outer loop or out of both loops only");
2333       if (!loop->is_member(u_loop)) {
2334         if (outer_loop->is_member(u_loop)) {
2335           wq.push(u);
2336         } else {
2337           // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
2338           // the outer loop too
2339           Node* u_c = u->in(0);
2340           if (u_c != nullptr) {
2341             IdealLoopTree* u_c_loop = phase->get_loop(u_c);
2342             if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
2343               wq.push(u);
2344             }
2345           }
2346         }
2347       }
2348     }
2349   }
2350 }
2351 
2352 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
2353                                       IdealLoopTree* outer_loop, int dd, Node_List &old_new,
2354                                       Node_List& extra_data_nodes) {
2355   if (head->is_strip_mined() && mode != IgnoreStripMined) {
2356     CountedLoopNode* cl = head->as_CountedLoop();
2357     Node* l = cl->outer_loop();
2358     Node* tail = cl->outer_loop_tail();
2359     IfNode* le = cl->outer_loop_end();
2360     Node* sfpt = cl->outer_safepoint();
2361     CountedLoopEndNode* cle = cl->loopexit();
2362     CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
2363     CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
2364     Node* cle_out = cle->proj_out(false);
2365 
2366     Node* new_sfpt = nullptr;
2367     Node* new_cle_out = cle_out->clone();
2368     old_new.map(cle_out->_idx, new_cle_out);
2369     if (mode == CloneIncludesStripMined) {
2370       // clone outer loop body
2371       Node* new_l = l->clone();
2372       Node* new_tail = tail->clone();
2373       IfNode* new_le = le->clone()->as_If();
2374       new_sfpt = sfpt->clone();
2375 
2376       set_loop(new_l, outer_loop->_parent);
2377       set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
2378       set_loop(new_cle_out, outer_loop->_parent);
2379       set_idom(new_cle_out, new_cle, dd);
2380       set_loop(new_sfpt, outer_loop->_parent);
2381       set_idom(new_sfpt, new_cle_out, dd);
2382       set_loop(new_le, outer_loop->_parent);
2383       set_idom(new_le, new_sfpt, dd);
2384       set_loop(new_tail, outer_loop->_parent);
2385       set_idom(new_tail, new_le, dd);
2386       set_idom(new_cl, new_l, dd);
2387 
2388       old_new.map(l->_idx, new_l);
2389       old_new.map(tail->_idx, new_tail);
2390       old_new.map(le->_idx, new_le);
2391       old_new.map(sfpt->_idx, new_sfpt);
2392 
2393       new_l->set_req(LoopNode::LoopBackControl, new_tail);
2394       new_l->set_req(0, new_l);
2395       new_tail->set_req(0, new_le);
2396       new_le->set_req(0, new_sfpt);
2397       new_sfpt->set_req(0, new_cle_out);
2398       new_cle_out->set_req(0, new_cle);
2399       new_cl->set_req(LoopNode::EntryControl, new_l);
2400 
2401       _igvn.register_new_node_with_optimizer(new_l);
2402       _igvn.register_new_node_with_optimizer(new_tail);
2403       _igvn.register_new_node_with_optimizer(new_le);
2404     } else {
2405       Node *newhead = old_new[loop->_head->_idx];
2406       newhead->as_Loop()->clear_strip_mined();
2407       _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
2408       set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2409     }
2410     // Look at data node that were assigned a control in the outer
2411     // loop: they are kept in the outer loop by the safepoint so start
2412     // from the safepoint node's inputs.
2413     IdealLoopTree* outer_loop = get_loop(l);
2414     Node_Stack stack(2);
2415     stack.push(sfpt, 1);
2416     uint new_counter = C->unique();
2417     while (stack.size() > 0) {
2418       Node* n = stack.node();
2419       uint i = stack.index();
2420       while (i < n->req() &&
2421              (n->in(i) == nullptr ||
2422               !has_ctrl(n->in(i)) ||
2423               get_loop(get_ctrl(n->in(i))) != outer_loop ||
2424               (old_new[n->in(i)->_idx] != nullptr && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
2425         i++;
2426       }
2427       if (i < n->req()) {
2428         stack.set_index(i+1);
2429         stack.push(n->in(i), 0);
2430       } else {
2431         assert(old_new[n->_idx] == nullptr || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
2432         Node* m = n == sfpt ? new_sfpt : n->clone();
2433         if (m != nullptr) {
2434           for (uint i = 0; i < n->req(); i++) {
2435             if (m->in(i) != nullptr && old_new[m->in(i)->_idx] != nullptr) {
2436               m->set_req(i, old_new[m->in(i)->_idx]);
2437             }
2438           }
2439         } else {
2440           assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2441         }
2442         if (n != sfpt) {
2443           extra_data_nodes.push(n);
2444           _igvn.register_new_node_with_optimizer(m);
2445           assert(get_ctrl(n) == cle_out, "what other control?");
2446           set_ctrl(m, new_cle_out);
2447           old_new.map(n->_idx, m);
2448         }
2449         stack.pop();
2450       }
2451     }
2452     if (mode == CloneIncludesStripMined) {
2453       _igvn.register_new_node_with_optimizer(new_sfpt);
2454       _igvn.register_new_node_with_optimizer(new_cle_out);
2455     }
2456     // Some other transformation may have pessimistically assigned some
2457     // data nodes to the outer loop. Set their control so they are out
2458     // of the outer loop.
2459     ResourceMark rm;
2460     Unique_Node_List wq;
2461     for (uint i = 0; i < extra_data_nodes.size(); i++) {
2462       Node* old = extra_data_nodes.at(i);
2463       collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2464     }
2465 
2466     for (uint i = 0; i < loop->_body.size(); i++) {
2467       Node* old = loop->_body.at(i);
2468       collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2469     }
2470 
2471     Node* inner_out = sfpt->in(0);
2472     if (inner_out->outcnt() > 1) {
2473       collect_nodes_in_outer_loop_not_reachable_from_sfpt(inner_out, loop, outer_loop, old_new, wq, this, true);
2474     }
2475 
2476     Node* new_ctrl = cl->outer_loop_exit();
2477     assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2478     for (uint i = 0; i < wq.size(); i++) {
2479       Node* n = wq.at(i);
2480       set_ctrl(n, new_ctrl);
2481       if (n->in(0) != nullptr) {
2482         _igvn.replace_input_of(n, 0, new_ctrl);
2483       }
2484       collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
2485     }
2486   } else {
2487     Node *newhead = old_new[loop->_head->_idx];
2488     set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2489   }
2490 }
2491 
2492 //------------------------------clone_loop-------------------------------------
2493 //
2494 //                   C L O N E   A   L O O P   B O D Y
2495 //
2496 // This is the basic building block of the loop optimizations.  It clones an
2497 // entire loop body.  It makes an old_new loop body mapping; with this mapping
2498 // you can find the new-loop equivalent to an old-loop node.  All new-loop
2499 // nodes are exactly equal to their old-loop counterparts, all edges are the
2500 // same.  All exits from the old-loop now have a RegionNode that merges the
2501 // equivalent new-loop path.  This is true even for the normal "loop-exit"
2502 // condition.  All uses of loop-invariant old-loop values now come from (one
2503 // or more) Phis that merge their new-loop equivalents.
2504 //
2505 // This operation leaves the graph in an illegal state: there are two valid
2506 // control edges coming from the loop pre-header to both loop bodies.  I'll
2507 // definitely have to hack the graph after running this transform.
2508 //
2509 // From this building block I will further edit edges to perform loop peeling
2510 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2511 //
2512 // Parameter side_by_size_idom:
2513 //   When side_by_size_idom is null, the dominator tree is constructed for
2514 //      the clone loop to dominate the original.  Used in construction of
2515 //      pre-main-post loop sequence.
2516 //   When nonnull, the clone and original are side-by-side, both are
2517 //      dominated by the side_by_side_idom node.  Used in construction of
2518 //      unswitched loops.
2519 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2520                                 CloneLoopMode mode, Node* side_by_side_idom) {
2521 
2522   LoopNode* head = loop->_head->as_Loop();
2523   head->verify_strip_mined(1);
2524 
2525   if (C->do_vector_loop() && PrintOpto) {
2526     const char* mname = C->method()->name()->as_quoted_ascii();
2527     if (mname != nullptr) {
2528       tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2529     }
2530   }
2531 
2532   CloneMap& cm = C->clone_map();
2533   if (C->do_vector_loop()) {
2534     cm.set_clone_idx(cm.max_gen()+1);
2535 #ifndef PRODUCT
2536     if (PrintOpto) {
2537       tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2538       loop->dump_head();
2539     }
2540 #endif
2541   }
2542 
2543   // Step 1: Clone the loop body.  Make the old->new mapping.
2544   clone_loop_body(loop->_body, old_new, &cm);
2545 
2546   IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2547 
2548   // Step 2: Fix the edges in the new body.  If the old input is outside the
2549   // loop use it.  If the old input is INside the loop, use the corresponding
2550   // new node instead.
2551   fix_body_edges(loop->_body, loop, old_new, dd, outer_loop->_parent, false);
2552 
2553   Node_List extra_data_nodes; // data nodes in the outer strip mined loop
2554   clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2555 
2556   // Step 3: Now fix control uses.  Loop varying control uses have already
2557   // been fixed up (as part of all input edges in Step 2).  Loop invariant
2558   // control uses must be either an IfFalse or an IfTrue.  Make a merge
2559   // point to merge the old and new IfFalse/IfTrue nodes; make the use
2560   // refer to this.
2561   Node_List worklist;
2562   uint new_counter = C->unique();
2563   fix_ctrl_uses(loop->_body, loop, old_new, mode, side_by_side_idom, &cm, worklist);
2564 
2565   // Step 4: If loop-invariant use is not control, it must be dominated by a
2566   // loop exit IfFalse/IfTrue.  Find "proper" loop exit.  Make a Region
2567   // there if needed.  Make a Phi there merging old and new used values.
2568   Node_List *split_if_set = nullptr;
2569   Node_List *split_bool_set = nullptr;
2570   Node_List *split_cex_set = nullptr;
2571   fix_data_uses(loop->_body, loop, mode, outer_loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
2572 
2573   for (uint i = 0; i < extra_data_nodes.size(); i++) {
2574     Node* old = extra_data_nodes.at(i);
2575     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2576                                 split_bool_set, split_cex_set, worklist, new_counter,
2577                                 mode);
2578   }
2579 
2580   // Check for IFs that need splitting/cloning.  Happens if an IF outside of
2581   // the loop uses a condition set in the loop.  The original IF probably
2582   // takes control from one or more OLD Regions (which in turn get from NEW
2583   // Regions).  In any case, there will be a set of Phis for each merge point
2584   // from the IF up to where the original BOOL def exists the loop.
2585   finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
2586 
2587 }
2588 
2589 void PhaseIdealLoop::finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set) {
2590   if (split_if_set) {
2591     while (split_if_set->size()) {
2592       Node *iff = split_if_set->pop();
2593       uint input = iff->Opcode() == Op_AllocateArray ? AllocateNode::ValidLengthTest : 1;
2594       if (iff->in(input)->is_Phi()) {
2595         Node *b = clone_iff(iff->in(input)->as_Phi());
2596         _igvn.replace_input_of(iff, input, b);
2597       }
2598     }
2599   }
2600   if (split_bool_set) {
2601     while (split_bool_set->size()) {
2602       Node *b = split_bool_set->pop();
2603       Node *phi = b->in(1);
2604       assert(phi->is_Phi(), "");
2605       CmpNode *cmp = clone_bool((PhiNode*) phi);
2606       _igvn.replace_input_of(b, 1, cmp);
2607     }
2608   }
2609   if (split_cex_set) {
2610     while (split_cex_set->size()) {
2611       Node *b = split_cex_set->pop();
2612       assert(b->in(0)->is_Region(), "");
2613       assert(b->in(1)->is_Phi(), "");
2614       assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2615       split_up(b, b->in(0), nullptr);
2616     }
2617   }
2618 }
2619 
2620 void PhaseIdealLoop::fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
2621                                    uint new_counter, Node_List &old_new, Node_List &worklist, Node_List*& split_if_set,
2622                                    Node_List*& split_bool_set, Node_List*& split_cex_set) {
2623   for(uint i = 0; i < body.size(); i++ ) {
2624     Node* old = body.at(i);
2625     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2626                                 split_bool_set, split_cex_set, worklist, new_counter,
2627                                 mode);
2628   }
2629 }
2630 
2631 void PhaseIdealLoop::fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
2632                                    Node* side_by_side_idom, CloneMap* cm, Node_List &worklist) {
2633   LoopNode* head = loop->_head->as_Loop();
2634   for(uint i = 0; i < body.size(); i++ ) {
2635     Node* old = body.at(i);
2636     if( !old->is_CFG() ) continue;
2637 
2638     // Copy uses to a worklist, so I can munge the def-use info
2639     // with impunity.
2640     for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) {
2641       worklist.push(old->fast_out(j));
2642     }
2643 
2644     while (worklist.size()) {  // Visit all uses
2645       Node *use = worklist.pop();
2646       if (!has_node(use))  continue; // Ignore dead nodes
2647       IdealLoopTree *use_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use );
2648       if (!loop->is_member(use_loop) && use->is_CFG()) {
2649         // Both OLD and USE are CFG nodes here.
2650         assert(use->is_Proj(), "" );
2651         Node* nnn = old_new[old->_idx];
2652 
2653         Node* newuse = nullptr;
2654         if (head->is_strip_mined() && mode != IgnoreStripMined) {
2655           CountedLoopNode* cl = head->as_CountedLoop();
2656           CountedLoopEndNode* cle = cl->loopexit();
2657           Node* cle_out = cle->proj_out_or_null(false);
2658           if (use == cle_out) {
2659             IfNode* le = cl->outer_loop_end();
2660             use = le->proj_out(false);
2661             use_loop = get_loop(use);
2662             if (mode == CloneIncludesStripMined) {
2663               nnn = old_new[le->_idx];
2664             } else {
2665               newuse = old_new[cle_out->_idx];
2666             }
2667           }
2668         }
2669         if (newuse == nullptr) {
2670           newuse = use->clone();
2671         }
2672 
2673         // Clone the loop exit control projection
2674         if (C->do_vector_loop() && cm != nullptr) {
2675           cm->verify_insert_and_clone(use, newuse, cm->clone_idx());
2676         }
2677         newuse->set_req(0,nnn);
2678         _igvn.register_new_node_with_optimizer(newuse);
2679         set_loop(newuse, use_loop);
2680         set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2681 
2682         // We need a Region to merge the exit from the peeled body and the
2683         // exit from the old loop body.
2684         RegionNode *r = new RegionNode(3);
2685         uint dd_r = MIN2(dom_depth(newuse), dom_depth(use));
2686         assert(dd_r >= dom_depth(dom_lca(newuse, use)), "" );
2687 
2688         // The original user of 'use' uses 'r' instead.
2689         for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2690           Node* useuse = use->last_out(l);
2691           _igvn.rehash_node_delayed(useuse);
2692           uint uses_found = 0;
2693           if (useuse->in(0) == use) {
2694             useuse->set_req(0, r);
2695             uses_found++;
2696             if (useuse->is_CFG()) {
2697               // This is not a dom_depth > dd_r because when new
2698               // control flow is constructed by a loop opt, a node and
2699               // its dominator can end up at the same dom_depth
2700               assert(dom_depth(useuse) >= dd_r, "");
2701               set_idom(useuse, r, dom_depth(useuse));
2702             }
2703           }
2704           for (uint k = 1; k < useuse->req(); k++) {
2705             if( useuse->in(k) == use ) {
2706               useuse->set_req(k, r);
2707               uses_found++;
2708               if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2709                 // This is not a dom_depth > dd_r because when new
2710                 // control flow is constructed by a loop opt, a node
2711                 // and its dominator can end up at the same dom_depth
2712                 assert(dom_depth(useuse) >= dd_r , "");
2713                 set_idom(useuse, r, dom_depth(useuse));
2714               }
2715             }
2716           }
2717           l -= uses_found;    // we deleted 1 or more copies of this edge
2718         }
2719 
2720         assert(use->is_Proj(), "loop exit should be projection");
2721         // lazy_replace() below moves all nodes that are:
2722         // - control dependent on the loop exit or
2723         // - have control set to the loop exit
2724         // below the post-loop merge point. lazy_replace() takes a dead control as first input. To make it
2725         // possible to use it, the loop exit projection is cloned and becomes the new exit projection. The initial one
2726         // becomes dead and is "replaced" by the region.
2727         Node* use_clone = use->clone();
2728         register_control(use_clone, use_loop, idom(use), dom_depth(use));
2729         // Now finish up 'r'
2730         r->set_req(1, newuse);
2731         r->set_req(2, use_clone);
2732         _igvn.register_new_node_with_optimizer(r);
2733         set_loop(r, use_loop);
2734         set_idom(r, (side_by_side_idom == nullptr) ? newuse->in(0) : side_by_side_idom, dd_r);
2735         lazy_replace(use, r);
2736         // Map the (cloned) old use to the new merge point
2737         old_new.map(use_clone->_idx, r);
2738       } // End of if a loop-exit test
2739     }
2740   }
2741 }
2742 
2743 void PhaseIdealLoop::fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
2744                                     IdealLoopTree* parent, bool partial) {
2745   for(uint i = 0; i < body.size(); i++ ) {
2746     Node *old = body.at(i);
2747     Node *nnn = old_new[old->_idx];
2748     // Fix CFG/Loop controlling the new node
2749     if (has_ctrl(old)) {
2750       set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2751     } else {
2752       set_loop(nnn, parent);
2753       if (old->outcnt() > 0) {
2754         Node* dom = idom(old);
2755         if (old_new[dom->_idx] != nullptr) {
2756           dom = old_new[dom->_idx];
2757           set_idom(nnn, dom, dd );
2758         }
2759       }
2760     }
2761     // Correct edges to the new node
2762     for (uint j = 0; j < nnn->req(); j++) {
2763         Node *n = nnn->in(j);
2764         if (n != nullptr) {
2765           IdealLoopTree *old_in_loop = get_loop(has_ctrl(n) ? get_ctrl(n) : n);
2766           if (loop->is_member(old_in_loop)) {
2767             if (old_new[n->_idx] != nullptr) {
2768               nnn->set_req(j, old_new[n->_idx]);
2769             } else {
2770               assert(!body.contains(n), "");
2771               assert(partial, "node not cloned");
2772             }
2773           }
2774         }
2775     }
2776     _igvn.hash_find_insert(nnn);
2777   }
2778 }
2779 
2780 void PhaseIdealLoop::clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm) {
2781   for (uint i = 0; i < body.size(); i++) {
2782     Node* old = body.at(i);
2783     Node* nnn = old->clone();
2784     old_new.map(old->_idx, nnn);
2785     if (C->do_vector_loop() && cm != nullptr) {
2786       cm->verify_insert_and_clone(old, nnn, cm->clone_idx());
2787     }
2788     _igvn.register_new_node_with_optimizer(nnn);
2789   }
2790 }
2791 
2792 
2793 //---------------------- stride_of_possible_iv -------------------------------------
2794 // Looks for an iff/bool/comp with one operand of the compare
2795 // being a cycle involving an add and a phi,
2796 // with an optional truncation (left-shift followed by a right-shift)
2797 // of the add. Returns zero if not an iv.
2798 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2799   Node* trunc1 = nullptr;
2800   Node* trunc2 = nullptr;
2801   const TypeInteger* ttype = nullptr;
2802   if (!iff->is_If() || iff->in(1) == nullptr || !iff->in(1)->is_Bool()) {
2803     return 0;
2804   }
2805   BoolNode* bl = iff->in(1)->as_Bool();
2806   Node* cmp = bl->in(1);
2807   if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2808     return 0;
2809   }
2810   // Must have an invariant operand
2811   if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2812     return 0;
2813   }
2814   Node* add2 = nullptr;
2815   Node* cmp1 = cmp->in(1);
2816   if (cmp1->is_Phi()) {
2817     // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2818     Node* phi = cmp1;
2819     for (uint i = 1; i < phi->req(); i++) {
2820       Node* in = phi->in(i);
2821       Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2822                                 &trunc1, &trunc2, &ttype, T_INT);
2823       if (add && add->in(1) == phi) {
2824         add2 = add->in(2);
2825         break;
2826       }
2827     }
2828   } else {
2829     // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2830     Node* addtrunc = cmp1;
2831     Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2832                                 &trunc1, &trunc2, &ttype, T_INT);
2833     if (add && add->in(1)->is_Phi()) {
2834       Node* phi = add->in(1);
2835       for (uint i = 1; i < phi->req(); i++) {
2836         if (phi->in(i) == addtrunc) {
2837           add2 = add->in(2);
2838           break;
2839         }
2840       }
2841     }
2842   }
2843   if (add2 != nullptr) {
2844     const TypeInt* add2t = _igvn.type(add2)->is_int();
2845     if (add2t->is_con()) {
2846       return add2t->get_con();
2847     }
2848   }
2849   return 0;
2850 }
2851 
2852 
2853 //---------------------- stay_in_loop -------------------------------------
2854 // Return the (unique) control output node that's in the loop (if it exists.)
2855 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2856   Node* unique = nullptr;
2857   if (!n) return nullptr;
2858   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2859     Node* use = n->fast_out(i);
2860     if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2861       if (unique != nullptr) {
2862         return nullptr;
2863       }
2864       unique = use;
2865     }
2866   }
2867   return unique;
2868 }
2869 
2870 //------------------------------ register_node -------------------------------------
2871 // Utility to register node "n" with PhaseIdealLoop
2872 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth) {
2873   _igvn.register_new_node_with_optimizer(n);
2874   loop->_body.push(n);
2875   if (n->is_CFG()) {
2876     set_loop(n, loop);
2877     set_idom(n, pred, ddepth);
2878   } else {
2879     set_ctrl(n, pred);
2880   }
2881 }
2882 
2883 //------------------------------ proj_clone -------------------------------------
2884 // Utility to create an if-projection
2885 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2886   ProjNode* c = p->clone()->as_Proj();
2887   c->set_req(0, iff);
2888   return c;
2889 }
2890 
2891 //------------------------------ short_circuit_if -------------------------------------
2892 // Force the iff control output to be the live_proj
2893 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2894   guarantee(live_proj != nullptr, "null projection");
2895   int proj_con = live_proj->_con;
2896   assert(proj_con == 0 || proj_con == 1, "false or true projection");
2897   Node* con = intcon(proj_con);
2898   if (iff) {
2899     iff->set_req(1, con);
2900   }
2901   return con;
2902 }
2903 
2904 //------------------------------ insert_if_before_proj -------------------------------------
2905 // Insert a new if before an if projection (* - new node)
2906 //
2907 // before
2908 //           if(test)
2909 //           /     \
2910 //          v       v
2911 //    other-proj   proj (arg)
2912 //
2913 // after
2914 //           if(test)
2915 //           /     \
2916 //          /       v
2917 //         |      * proj-clone
2918 //         v          |
2919 //    other-proj      v
2920 //                * new_if(relop(cmp[IU](left,right)))
2921 //                  /  \
2922 //                 v    v
2923 //         * new-proj  proj
2924 //         (returned)
2925 //
2926 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2927   IfNode* iff = proj->in(0)->as_If();
2928   IdealLoopTree *loop = get_loop(proj);
2929   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2930   uint ddepth = dom_depth(proj);
2931 
2932   _igvn.rehash_node_delayed(iff);
2933   _igvn.rehash_node_delayed(proj);
2934 
2935   proj->set_req(0, nullptr);  // temporary disconnect
2936   ProjNode* proj2 = proj_clone(proj, iff);
2937   register_node(proj2, loop, iff, ddepth);
2938 
2939   Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2940   register_node(cmp, loop, proj2, ddepth);
2941 
2942   BoolNode* bol = new BoolNode(cmp, relop);
2943   register_node(bol, loop, proj2, ddepth);
2944 
2945   int opcode = iff->Opcode();
2946   assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2947   IfNode* new_if = IfNode::make_with_same_profile(iff, proj2, bol);
2948   register_node(new_if, loop, proj2, ddepth);
2949 
2950   proj->set_req(0, new_if); // reattach
2951   set_idom(proj, new_if, ddepth);
2952 
2953   ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2954   guarantee(new_exit != nullptr, "null exit node");
2955   register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2956 
2957   return new_exit;
2958 }
2959 
2960 //------------------------------ insert_region_before_proj -------------------------------------
2961 // Insert a region before an if projection (* - new node)
2962 //
2963 // before
2964 //           if(test)
2965 //          /      |
2966 //         v       |
2967 //       proj      v
2968 //               other-proj
2969 //
2970 // after
2971 //           if(test)
2972 //          /      |
2973 //         v       |
2974 // * proj-clone    v
2975 //         |     other-proj
2976 //         v
2977 // * new-region
2978 //         |
2979 //         v
2980 // *      dum_if
2981 //       /     \
2982 //      v       \
2983 // * dum-proj    v
2984 //              proj
2985 //
2986 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2987   IfNode* iff = proj->in(0)->as_If();
2988   IdealLoopTree *loop = get_loop(proj);
2989   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2990   uint ddepth = dom_depth(proj);
2991 
2992   _igvn.rehash_node_delayed(iff);
2993   _igvn.rehash_node_delayed(proj);
2994 
2995   proj->set_req(0, nullptr);  // temporary disconnect
2996   ProjNode* proj2 = proj_clone(proj, iff);
2997   register_node(proj2, loop, iff, ddepth);
2998 
2999   RegionNode* reg = new RegionNode(2);
3000   reg->set_req(1, proj2);
3001   register_node(reg, loop, iff, ddepth);
3002 
3003   IfNode* dum_if = new IfNode(reg, short_circuit_if(nullptr, proj), iff->_prob, iff->_fcnt);
3004   register_node(dum_if, loop, reg, ddepth);
3005 
3006   proj->set_req(0, dum_if); // reattach
3007   set_idom(proj, dum_if, ddepth);
3008 
3009   ProjNode* dum_proj = proj_clone(other_proj, dum_if);
3010   register_node(dum_proj, loop, dum_if, ddepth);
3011 
3012   return reg;
3013 }
3014 
3015 // Idea
3016 // ----
3017 // Partial Peeling tries to rotate the loop in such a way that it can later be turned into a counted loop. Counted loops
3018 // require a signed loop exit test. When calling this method, we've only found a suitable unsigned test to partial peel
3019 // with. Therefore, we try to split off a signed loop exit test from the unsigned test such that it can be used as new
3020 // loop exit while keeping the unsigned test unchanged and preserving the same behavior as if we've used the unsigned
3021 // test alone instead:
3022 //
3023 // Before Partial Peeling:
3024 //   Loop:
3025 //     <peeled section>
3026 //     Split off signed loop exit test
3027 //     <-- CUT HERE -->
3028 //     Unchanged unsigned loop exit test
3029 //     <rest of unpeeled section>
3030 //     goto Loop
3031 //
3032 // After Partial Peeling:
3033 //   <cloned peeled section>
3034 //   Cloned split off signed loop exit test
3035 //   Loop:
3036 //     Unchanged unsigned loop exit test
3037 //     <rest of unpeeled section>
3038 //     <peeled section>
3039 //     Split off signed loop exit test
3040 //     goto Loop
3041 //
3042 // Details
3043 // -------
3044 // Before:
3045 //          if (i <u limit)    Unsigned loop exit condition
3046 //         /       |
3047 //        v        v
3048 //   exit-proj   stay-in-loop-proj
3049 //
3050 // Split off a signed loop exit test (i.e. with CmpI) from an unsigned loop exit test (i.e. with CmpU) and insert it
3051 // before the CmpU on the stay-in-loop path and keep both tests:
3052 //
3053 //          if (i <u limit)    Signed loop exit test
3054 //        /        |
3055 //       /  if (i <u limit)    Unsigned loop exit test
3056 //      /  /       |
3057 //     v  v        v
3058 //  exit-region  stay-in-loop-proj
3059 //
3060 // Implementation
3061 // --------------
3062 // We need to make sure that the new signed loop exit test is properly inserted into the graph such that the unsigned
3063 // loop exit test still dominates the same set of control nodes, the ctrl() relation from data nodes to both loop
3064 // exit tests is preserved, and their loop nesting is correct.
3065 //
3066 // To achieve that, we clone the unsigned loop exit test completely (leave it unchanged), insert the signed loop exit
3067 // test above it and kill the original unsigned loop exit test by setting it's condition to a constant
3068 // (i.e. stay-in-loop-const in graph below) such that IGVN can fold it later:
3069 //
3070 //           if (stay-in-loop-const)  Killed original unsigned loop exit test
3071 //          /       |
3072 //         /        v
3073 //        /  if (i <  limit)          Split off signed loop exit test
3074 //       /  /       |
3075 //      /  /        v
3076 //     /  /  if (i <u limit)          Cloned unsigned loop exit test
3077 //    /  /   /      |
3078 //   v  v  v        |
3079 //  exit-region     |
3080 //        |         |
3081 //    dummy-if      |
3082 //     /  |         |
3083 // dead   |         |
3084 //        v         v
3085 //   exit-proj   stay-in-loop-proj
3086 //
3087 // Note: The dummy-if is inserted to create a region to merge the loop exits between the original to be killed unsigned
3088 //       loop exit test and its exit projection while keeping the exit projection (also see insert_region_before_proj()).
3089 //
3090 // Requirements
3091 // ------------
3092 // Note that we can only split off a signed loop exit test from the unsigned loop exit test when the behavior is exactly
3093 // the same as before with only a single unsigned test. This is only possible if certain requirements are met.
3094 // Otherwise, we need to bail out (see comments in the code below).
3095 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree* loop) {
3096   const bool Signed   = true;
3097   const bool Unsigned = false;
3098 
3099   BoolNode* bol = if_cmpu->in(1)->as_Bool();
3100   if (bol->_test._test != BoolTest::lt) {
3101     return nullptr;
3102   }
3103   CmpNode* cmpu = bol->in(1)->as_Cmp();
3104   assert(cmpu->Opcode() == Op_CmpU, "must be unsigned comparison");
3105 
3106   int stride = stride_of_possible_iv(if_cmpu);
3107   if (stride == 0) {
3108     return nullptr;
3109   }
3110 
3111   Node* lp_proj = stay_in_loop(if_cmpu, loop);
3112   guarantee(lp_proj != nullptr, "null loop node");
3113 
3114   ProjNode* lp_continue = lp_proj->as_Proj();
3115   ProjNode* lp_exit     = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
3116   if (!lp_exit->is_IfFalse()) {
3117     // The loop exit condition is (i <u limit) ==> (i >= 0 && i < limit).
3118     // We therefore can't add a single exit condition.
3119     return nullptr;
3120   }
3121   // The unsigned loop exit condition is
3122   //   !(i <u  limit)
3123   // =   i >=u limit
3124   //
3125   // First, we note that for any x for which
3126   //   0 <= x <= INT_MAX
3127   // we can convert x to an unsigned int and still get the same guarantee:
3128   //   0 <=  (uint) x <=  INT_MAX = (uint) INT_MAX
3129   //   0 <=u (uint) x <=u INT_MAX = (uint) INT_MAX   (LEMMA)
3130   //
3131   // With that in mind, if
3132   //   limit >= 0             (COND)
3133   // then the unsigned loop exit condition
3134   //   i >=u limit            (ULE)
3135   // is equivalent to
3136   //   i < 0 || i >= limit    (SLE-full)
3137   // because either i is negative and therefore always greater than MAX_INT when converting to unsigned
3138   //   (uint) i >=u MAX_INT >= limit >= 0
3139   // or otherwise
3140   //   i >= limit >= 0
3141   // holds due to (LEMMA).
3142   //
3143   // For completeness, a counterexample with limit < 0:
3144   // Assume i = -3 and limit = -2:
3145   //   i  < 0
3146   //   -2 < 0
3147   // is true and thus also "i < 0 || i >= limit". But
3148   //   i  >=u limit
3149   //   -3 >=u -2
3150   // is false.
3151   Node* limit = cmpu->in(2);
3152   const TypeInt* type_limit = _igvn.type(limit)->is_int();
3153   if (type_limit->_lo < 0) {
3154     return nullptr;
3155   }
3156 
3157   // We prove below that we can extract a single signed loop exit condition from (SLE-full), depending on the stride:
3158   //   stride < 0:
3159   //     i < 0        (SLE = SLE-negative)
3160   //   stride > 0:
3161   //     i >= limit   (SLE = SLE-positive)
3162   // such that we have the following graph before Partial Peeling with stride > 0 (similar for stride < 0):
3163   //
3164   // Loop:
3165   //   <peeled section>
3166   //   i >= limit    (SLE-positive)
3167   //   <-- CUT HERE -->
3168   //   i >=u limit   (ULE)
3169   //   <rest of unpeeled section>
3170   //   goto Loop
3171   //
3172   // We exit the loop if:
3173   //   (SLE) is true OR (ULE) is true
3174   // However, if (SLE) is true then (ULE) also needs to be true to ensure the exact same behavior. Otherwise, we wrongly
3175   // exit a loop that should not have been exited if we did not apply Partial Peeling. More formally, we need to ensure:
3176   //   (SLE) IMPLIES (ULE)
3177   // This indeed holds when (COND) is given:
3178   // - stride > 0:
3179   //       i >=  limit             // (SLE = SLE-positive)
3180   //       i >=  limit >= 0        // (COND)
3181   //       i >=u limit >= 0        // (LEMMA)
3182   //     which is the unsigned loop exit condition (ULE).
3183   // - stride < 0:
3184   //       i        <  0           // (SLE = SLE-negative)
3185   //       (uint) i >u MAX_INT     // (NEG) all negative values are greater than MAX_INT when converted to unsigned
3186   //       MAX_INT >= limit >= 0   // (COND)
3187   //       MAX_INT >=u limit >= 0  // (LEMMA)
3188   //     and thus from (NEG) and (LEMMA):
3189   //       i >=u limit
3190   //     which is the unsigned loop exit condition (ULE).
3191   //
3192   //
3193   // After Partial Peeling, we have the following structure for stride > 0 (similar for stride < 0):
3194   //   <cloned peeled section>
3195   //   i >= limit (SLE-positive)
3196   //   Loop:
3197   //     i >=u limit (ULE)
3198   //     <rest of unpeeled section>
3199   //     <peeled section>
3200   //     i >= limit (SLE-positive)
3201   //     goto Loop
3202   Node* rhs_cmpi;
3203   if (stride > 0) {
3204     rhs_cmpi = limit; // For i >= limit
3205   } else {
3206     rhs_cmpi = makecon(TypeInt::ZERO); // For i < 0
3207   }
3208   // Create a new region on the exit path
3209   RegionNode* reg = insert_region_before_proj(lp_exit);
3210   guarantee(reg != nullptr, "null region node");
3211 
3212   // Clone the if-cmpu-true-false using a signed compare
3213   BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
3214   ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, rhs_cmpi, lp_continue);
3215   reg->add_req(cmpi_exit);
3216 
3217   // Clone the if-cmpu-true-false
3218   BoolTest::mask rel_u = bol->_test._test;
3219   ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
3220   reg->add_req(cmpu_exit);
3221 
3222   // Force original if to stay in loop.
3223   short_circuit_if(if_cmpu, lp_continue);
3224 
3225   return cmpi_exit->in(0)->as_If();
3226 }
3227 
3228 //------------------------------ remove_cmpi_loop_exit -------------------------------------
3229 // Remove a previously inserted signed compare loop exit.
3230 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
3231   Node* lp_proj = stay_in_loop(if_cmp, loop);
3232   assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
3233          stay_in_loop(lp_proj, loop)->is_If() &&
3234          stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
3235   Node* con = makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
3236   if_cmp->set_req(1, con);
3237 }
3238 
3239 //------------------------------ scheduled_nodelist -------------------------------------
3240 // Create a post order schedule of nodes that are in the
3241 // "member" set.  The list is returned in "sched".
3242 // The first node in "sched" is the loop head, followed by
3243 // nodes which have no inputs in the "member" set, and then
3244 // followed by the nodes that have an immediate input dependence
3245 // on a node in "sched".
3246 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
3247 
3248   assert(member.test(loop->_head->_idx), "loop head must be in member set");
3249   VectorSet visited;
3250   Node_Stack nstack(loop->_body.size());
3251 
3252   Node* n  = loop->_head;  // top of stack is cached in "n"
3253   uint idx = 0;
3254   visited.set(n->_idx);
3255 
3256   // Initially push all with no inputs from within member set
3257   for(uint i = 0; i < loop->_body.size(); i++ ) {
3258     Node *elt = loop->_body.at(i);
3259     if (member.test(elt->_idx)) {
3260       bool found = false;
3261       for (uint j = 0; j < elt->req(); j++) {
3262         Node* def = elt->in(j);
3263         if (def && member.test(def->_idx) && def != elt) {
3264           found = true;
3265           break;
3266         }
3267       }
3268       if (!found && elt != loop->_head) {
3269         nstack.push(n, idx);
3270         n = elt;
3271         assert(!visited.test(n->_idx), "not seen yet");
3272         visited.set(n->_idx);
3273       }
3274     }
3275   }
3276 
3277   // traverse out's that are in the member set
3278   while (true) {
3279     if (idx < n->outcnt()) {
3280       Node* use = n->raw_out(idx);
3281       idx++;
3282       if (!visited.test_set(use->_idx)) {
3283         if (member.test(use->_idx)) {
3284           nstack.push(n, idx);
3285           n = use;
3286           idx = 0;
3287         }
3288       }
3289     } else {
3290       // All outputs processed
3291       sched.push(n);
3292       if (nstack.is_empty()) break;
3293       n   = nstack.node();
3294       idx = nstack.index();
3295       nstack.pop();
3296     }
3297   }
3298 }
3299 
3300 
3301 //------------------------------ has_use_in_set -------------------------------------
3302 // Has a use in the vector set
3303 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
3304   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3305     Node* use = n->fast_out(j);
3306     if (vset.test(use->_idx)) {
3307       return true;
3308     }
3309   }
3310   return false;
3311 }
3312 
3313 
3314 //------------------------------ has_use_internal_to_set -------------------------------------
3315 // Has use internal to the vector set (ie. not in a phi at the loop head)
3316 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
3317   Node* head  = loop->_head;
3318   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3319     Node* use = n->fast_out(j);
3320     if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
3321       return true;
3322     }
3323   }
3324   return false;
3325 }
3326 
3327 
3328 //------------------------------ clone_for_use_outside_loop -------------------------------------
3329 // clone "n" for uses that are outside of loop
3330 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
3331   int cloned = 0;
3332   assert(worklist.size() == 0, "should be empty");
3333   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3334     Node* use = n->fast_out(j);
3335     if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
3336       worklist.push(use);
3337     }
3338   }
3339 
3340   if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor,
3341                           "Too many clones required in clone_for_use_outside_loop in partial peeling")) {
3342     return -1;
3343   }
3344 
3345   while( worklist.size() ) {
3346     Node *use = worklist.pop();
3347     if (!has_node(use) || use->in(0) == C->top()) continue;
3348     uint j;
3349     for (j = 0; j < use->req(); j++) {
3350       if (use->in(j) == n) break;
3351     }
3352     assert(j < use->req(), "must be there");
3353 
3354     // clone "n" and insert it between the inputs of "n" and the use outside the loop
3355     Node* n_clone = n->clone();
3356     _igvn.replace_input_of(use, j, n_clone);
3357     cloned++;
3358     Node* use_c;
3359     if (!use->is_Phi()) {
3360       use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
3361     } else {
3362       // Use in a phi is considered a use in the associated predecessor block
3363       use_c = use->in(0)->in(j);
3364     }
3365     set_ctrl(n_clone, use_c);
3366     assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
3367     get_loop(use_c)->_body.push(n_clone);
3368     _igvn.register_new_node_with_optimizer(n_clone);
3369 #ifndef PRODUCT
3370     if (TracePartialPeeling) {
3371       tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
3372     }
3373 #endif
3374   }
3375   return cloned;
3376 }
3377 
3378 
3379 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
3380 // clone "n" for special uses that are in the not_peeled region.
3381 // If these def-uses occur in separate blocks, the code generator
3382 // marks the method as not compilable.  For example, if a "BoolNode"
3383 // is in a different basic block than the "IfNode" that uses it, then
3384 // the compilation is aborted in the code generator.
3385 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
3386                                                         VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
3387   if (n->is_Phi() || n->is_Load()) {
3388     return;
3389   }
3390   assert(worklist.size() == 0, "should be empty");
3391   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3392     Node* use = n->fast_out(j);
3393     if ( not_peel.test(use->_idx) &&
3394          (use->is_If() || use->is_CMove() || use->is_Bool()) &&
3395          use->in(1) == n)  {
3396       worklist.push(use);
3397     }
3398   }
3399   if (worklist.size() > 0) {
3400     // clone "n" and insert it between inputs of "n" and the use
3401     Node* n_clone = n->clone();
3402     loop->_body.push(n_clone);
3403     _igvn.register_new_node_with_optimizer(n_clone);
3404     set_ctrl(n_clone, get_ctrl(n));
3405     sink_list.push(n_clone);
3406     not_peel.set(n_clone->_idx);
3407 #ifndef PRODUCT
3408     if (TracePartialPeeling) {
3409       tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
3410     }
3411 #endif
3412     while( worklist.size() ) {
3413       Node *use = worklist.pop();
3414       _igvn.rehash_node_delayed(use);
3415       for (uint j = 1; j < use->req(); j++) {
3416         if (use->in(j) == n) {
3417           use->set_req(j, n_clone);
3418         }
3419       }
3420     }
3421   }
3422 }
3423 
3424 
3425 //------------------------------ insert_phi_for_loop -------------------------------------
3426 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
3427 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
3428   Node *phi = PhiNode::make(lp, back_edge_val);
3429   phi->set_req(LoopNode::EntryControl, lp_entry_val);
3430   // Use existing phi if it already exists
3431   Node *hit = _igvn.hash_find_insert(phi);
3432   if( hit == nullptr ) {
3433     _igvn.register_new_node_with_optimizer(phi);
3434     set_ctrl(phi, lp);
3435   } else {
3436     // Remove the new phi from the graph and use the hit
3437     _igvn.remove_dead_node(phi);
3438     phi = hit;
3439   }
3440   _igvn.replace_input_of(use, idx, phi);
3441 }
3442 
3443 #ifdef ASSERT
3444 //------------------------------ is_valid_loop_partition -------------------------------------
3445 // Validate the loop partition sets: peel and not_peel
3446 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
3447                                               VectorSet& not_peel ) {
3448   uint i;
3449   // Check that peel_list entries are in the peel set
3450   for (i = 0; i < peel_list.size(); i++) {
3451     if (!peel.test(peel_list.at(i)->_idx)) {
3452       return false;
3453     }
3454   }
3455   // Check at loop members are in one of peel set or not_peel set
3456   for (i = 0; i < loop->_body.size(); i++ ) {
3457     Node *def  = loop->_body.at(i);
3458     uint di = def->_idx;
3459     // Check that peel set elements are in peel_list
3460     if (peel.test(di)) {
3461       if (not_peel.test(di)) {
3462         return false;
3463       }
3464       // Must be in peel_list also
3465       bool found = false;
3466       for (uint j = 0; j < peel_list.size(); j++) {
3467         if (peel_list.at(j)->_idx == di) {
3468           found = true;
3469           break;
3470         }
3471       }
3472       if (!found) {
3473         return false;
3474       }
3475     } else if (not_peel.test(di)) {
3476       if (peel.test(di)) {
3477         return false;
3478       }
3479     } else {
3480       return false;
3481     }
3482   }
3483   return true;
3484 }
3485 
3486 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
3487 // Ensure a use outside of loop is of the right form
3488 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
3489   Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3490   return (use->is_Phi() &&
3491           use_c->is_Region() && use_c->req() == 3 &&
3492           (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
3493            use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
3494            use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
3495           loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
3496 }
3497 
3498 //------------------------------ is_valid_clone_loop_form -------------------------------------
3499 // Ensure that all uses outside of loop are of the right form
3500 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
3501                                                uint orig_exit_idx, uint clone_exit_idx) {
3502   uint len = peel_list.size();
3503   for (uint i = 0; i < len; i++) {
3504     Node *def = peel_list.at(i);
3505 
3506     for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3507       Node *use = def->fast_out(j);
3508       Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3509       if (!loop->is_member(get_loop(use_c))) {
3510         // use is not in the loop, check for correct structure
3511         if (use->in(0) == def) {
3512           // Okay
3513         } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
3514           return false;
3515         }
3516       }
3517     }
3518   }
3519   return true;
3520 }
3521 #endif
3522 
3523 //------------------------------ partial_peel -------------------------------------
3524 // Partially peel (aka loop rotation) the top portion of a loop (called
3525 // the peel section below) by cloning it and placing one copy just before
3526 // the new loop head and the other copy at the bottom of the new loop.
3527 //
3528 //    before                       after                where it came from
3529 //
3530 //    stmt1                        stmt1
3531 //  loop:                          stmt2                     clone
3532 //    stmt2                        if condA goto exitA       clone
3533 //    if condA goto exitA        new_loop:                   new
3534 //    stmt3                        stmt3                     clone
3535 //    if !condB goto loop          if condB goto exitB       clone
3536 //  exitB:                         stmt2                     orig
3537 //    stmt4                        if !condA goto new_loop   orig
3538 //  exitA:                         goto exitA
3539 //                               exitB:
3540 //                                 stmt4
3541 //                               exitA:
3542 //
3543 // Step 1: find the cut point: an exit test on probable
3544 //         induction variable.
3545 // Step 2: schedule (with cloning) operations in the peel
3546 //         section that can be executed after the cut into
3547 //         the section that is not peeled.  This may need
3548 //         to clone operations into exit blocks.  For
3549 //         instance, a reference to A[i] in the not-peel
3550 //         section and a reference to B[i] in an exit block
3551 //         may cause a left-shift of i by 2 to be placed
3552 //         in the peel block.  This step will clone the left
3553 //         shift into the exit block and sink the left shift
3554 //         from the peel to the not-peel section.
3555 // Step 3: clone the loop, retarget the control, and insert
3556 //         phis for values that are live across the new loop
3557 //         head.  This is very dependent on the graph structure
3558 //         from clone_loop.  It creates region nodes for
3559 //         exit control and associated phi nodes for values
3560 //         flow out of the loop through that exit.  The region
3561 //         node is dominated by the clone's control projection.
3562 //         So the clone's peel section is placed before the
3563 //         new loop head, and the clone's not-peel section is
3564 //         forms the top part of the new loop.  The original
3565 //         peel section forms the tail of the new loop.
3566 // Step 4: update the dominator tree and recompute the
3567 //         dominator depth.
3568 //
3569 //                   orig
3570 //
3571 //                   stmt1
3572 //                     |
3573 //                     v
3574 //                 predicates
3575 //                     |
3576 //                     v
3577 //                   loop<----+
3578 //                     |      |
3579 //                   stmt2    |
3580 //                     |      |
3581 //                     v      |
3582 //                    ifA     |
3583 //                   / |      |
3584 //                  v  v      |
3585 //               false true   ^  <-- last_peel
3586 //               /     |      |
3587 //              /   ===|==cut |
3588 //             /     stmt3    |  <-- first_not_peel
3589 //            /        |      |
3590 //            |        v      |
3591 //            v       ifB     |
3592 //          exitA:   / \      |
3593 //                  /   \     |
3594 //                 v     v    |
3595 //               false true   |
3596 //               /       \    |
3597 //              /         ----+
3598 //             |
3599 //             v
3600 //           exitB:
3601 //           stmt4
3602 //
3603 //
3604 //            after clone loop
3605 //
3606 //                   stmt1
3607 //                     |
3608 //                     v
3609 //                predicates
3610 //                 /       \
3611 //        clone   /         \   orig
3612 //               /           \
3613 //              /             \
3614 //             v               v
3615 //   +---->loop                loop<----+
3616 //   |      |                    |      |
3617 //   |    stmt2                stmt2    |
3618 //   |      |                    |      |
3619 //   |      v                    v      |
3620 //   |      ifA                 ifA     |
3621 //   |      | \                / |      |
3622 //   |      v  v              v  v      |
3623 //   ^    true  false      false true   ^  <-- last_peel
3624 //   |      |   ^   \       /    |      |
3625 //   | cut==|==  \   \     /  ===|==cut |
3626 //   |    stmt3   \   \   /    stmt3    |  <-- first_not_peel
3627 //   |      |    dom   | |       |      |
3628 //   |      v      \  1v v2      v      |
3629 //   |      ifB     regionA     ifB     |
3630 //   |      / \        |       / \      |
3631 //   |     /   \       v      /   \     |
3632 //   |    v     v    exitA:  v     v    |
3633 //   |    true  false      false true   |
3634 //   |    /     ^   \      /       \    |
3635 //   +----       \   \    /         ----+
3636 //               dom  \  /
3637 //                 \  1v v2
3638 //                  regionB
3639 //                     |
3640 //                     v
3641 //                   exitB:
3642 //                   stmt4
3643 //
3644 //
3645 //           after partial peel
3646 //
3647 //                  stmt1
3648 //                     |
3649 //                     v
3650 //                predicates
3651 //                 /
3652 //        clone   /             orig
3653 //               /          TOP
3654 //              /             \
3655 //             v               v
3656 //    TOP->loop                loop----+
3657 //          |                    |      |
3658 //        stmt2                stmt2    |
3659 //          |                    |      |
3660 //          v                    v      |
3661 //          ifA                 ifA     |
3662 //          | \                / |      |
3663 //          v  v              v  v      |
3664 //        true  false      false true   |     <-- last_peel
3665 //          |   ^   \       /    +------|---+
3666 //  +->newloop   \   \     /  === ==cut |   |
3667 //  |     stmt3   \   \   /     TOP     |   |
3668 //  |       |    dom   | |      stmt3   |   | <-- first_not_peel
3669 //  |       v      \  1v v2      v      |   |
3670 //  |       ifB     regionA     ifB     ^   v
3671 //  |       / \        |       / \      |   |
3672 //  |      /   \       v      /   \     |   |
3673 //  |     v     v    exitA:  v     v    |   |
3674 //  |     true  false      false true   |   |
3675 //  |     /     ^   \      /       \    |   |
3676 //  |    |       \   \    /         v   |   |
3677 //  |    |       dom  \  /         TOP  |   |
3678 //  |    |         \  1v v2             |   |
3679 //  ^    v          regionB             |   |
3680 //  |    |             |                |   |
3681 //  |    |             v                ^   v
3682 //  |    |           exitB:             |   |
3683 //  |    |           stmt4              |   |
3684 //  |    +------------>-----------------+   |
3685 //  |                                       |
3686 //  +-----------------<---------------------+
3687 //
3688 //
3689 //              final graph
3690 //
3691 //                  stmt1
3692 //                    |
3693 //                    v
3694 //                predicates
3695 //                    |
3696 //                    v
3697 //                  stmt2 clone
3698 //                    |
3699 //                    v
3700 //         ........> ifA clone
3701 //         :        / |
3702 //        dom      /  |
3703 //         :      v   v
3704 //         :  false   true
3705 //         :  |       |
3706 //         :  |       v
3707 //         :  |    newloop<-----+
3708 //         :  |        |        |
3709 //         :  |     stmt3 clone |
3710 //         :  |        |        |
3711 //         :  |        v        |
3712 //         :  |       ifB       |
3713 //         :  |      / \        |
3714 //         :  |     v   v       |
3715 //         :  |  false true     |
3716 //         :  |   |     |       |
3717 //         :  |   v    stmt2    |
3718 //         :  | exitB:  |       |
3719 //         :  | stmt4   v       |
3720 //         :  |       ifA orig  |
3721 //         :  |      /  \       |
3722 //         :  |     /    \      |
3723 //         :  |    v     v      |
3724 //         :  |  false  true    |
3725 //         :  |  /        \     |
3726 //         :  v  v         -----+
3727 //          RegionA
3728 //             |
3729 //             v
3730 //           exitA
3731 //
3732 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3733 
3734   assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3735   if (!loop->_head->is_Loop()) {
3736     return false;
3737   }
3738   LoopNode *head = loop->_head->as_Loop();
3739 
3740   if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3741     return false;
3742   }
3743 
3744   // Check for complex exit control
3745   for (uint ii = 0; ii < loop->_body.size(); ii++) {
3746     Node *n = loop->_body.at(ii);
3747     int opc = n->Opcode();
3748     if (n->is_Call()        ||
3749         opc == Op_Catch     ||
3750         opc == Op_CatchProj ||
3751         opc == Op_Jump      ||
3752         opc == Op_JumpProj) {
3753 #ifndef PRODUCT
3754       if (TracePartialPeeling) {
3755         tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3756       }
3757 #endif
3758       return false;
3759     }
3760   }
3761 
3762   int dd = dom_depth(head);
3763 
3764   // Step 1: find cut point
3765 
3766   // Walk up dominators to loop head looking for first loop exit
3767   // which is executed on every path thru loop.
3768   IfNode *peel_if = nullptr;
3769   IfNode *peel_if_cmpu = nullptr;
3770 
3771   Node *iff = loop->tail();
3772   while (iff != head) {
3773     if (iff->is_If()) {
3774       Node *ctrl = get_ctrl(iff->in(1));
3775       if (ctrl->is_top()) return false; // Dead test on live IF.
3776       // If loop-varying exit-test, check for induction variable
3777       if (loop->is_member(get_loop(ctrl)) &&
3778           loop->is_loop_exit(iff) &&
3779           is_possible_iv_test(iff)) {
3780         Node* cmp = iff->in(1)->in(1);
3781         if (cmp->Opcode() == Op_CmpI) {
3782           peel_if = iff->as_If();
3783         } else {
3784           assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3785           peel_if_cmpu = iff->as_If();
3786         }
3787       }
3788     }
3789     iff = idom(iff);
3790   }
3791 
3792   // Prefer signed compare over unsigned compare.
3793   IfNode* new_peel_if = nullptr;
3794   if (peel_if == nullptr) {
3795     if (!PartialPeelAtUnsignedTests || peel_if_cmpu == nullptr) {
3796       return false;   // No peel point found
3797     }
3798     new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3799     if (new_peel_if == nullptr) {
3800       return false;   // No peel point found
3801     }
3802     peel_if = new_peel_if;
3803   }
3804   Node* last_peel        = stay_in_loop(peel_if, loop);
3805   Node* first_not_peeled = stay_in_loop(last_peel, loop);
3806   if (first_not_peeled == nullptr || first_not_peeled == head) {
3807     return false;
3808   }
3809 
3810 #ifndef PRODUCT
3811   if (TraceLoopOpts) {
3812     tty->print("PartialPeel  ");
3813     loop->dump_head();
3814   }
3815 
3816   if (TracePartialPeeling) {
3817     tty->print_cr("before partial peel one iteration");
3818     Node_List wl;
3819     Node* t = head->in(2);
3820     while (true) {
3821       wl.push(t);
3822       if (t == head) break;
3823       t = idom(t);
3824     }
3825     while (wl.size() > 0) {
3826       Node* tt = wl.pop();
3827       tt->dump();
3828       if (tt == last_peel) tty->print_cr("-- cut --");
3829     }
3830   }
3831 #endif
3832 
3833   C->print_method(PHASE_BEFORE_PARTIAL_PEELING, 4, head);
3834 
3835   VectorSet peel;
3836   VectorSet not_peel;
3837   Node_List peel_list;
3838   Node_List worklist;
3839   Node_List sink_list;
3840 
3841   uint estimate = loop->est_loop_clone_sz(1);
3842   if (exceeding_node_budget(estimate)) {
3843     return false;
3844   }
3845 
3846   // Set of cfg nodes to peel are those that are executable from
3847   // the head through last_peel.
3848   assert(worklist.size() == 0, "should be empty");
3849   worklist.push(head);
3850   peel.set(head->_idx);
3851   while (worklist.size() > 0) {
3852     Node *n = worklist.pop();
3853     if (n != last_peel) {
3854       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3855         Node* use = n->fast_out(j);
3856         if (use->is_CFG() &&
3857             loop->is_member(get_loop(use)) &&
3858             !peel.test_set(use->_idx)) {
3859           worklist.push(use);
3860         }
3861       }
3862     }
3863   }
3864 
3865   // Set of non-cfg nodes to peel are those that are control
3866   // dependent on the cfg nodes.
3867   for (uint i = 0; i < loop->_body.size(); i++) {
3868     Node *n = loop->_body.at(i);
3869     Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3870     if (peel.test(n_c->_idx)) {
3871       peel.set(n->_idx);
3872     } else {
3873       not_peel.set(n->_idx);
3874     }
3875   }
3876 
3877   // Step 2: move operations from the peeled section down into the
3878   //         not-peeled section
3879 
3880   // Get a post order schedule of nodes in the peel region
3881   // Result in right-most operand.
3882   scheduled_nodelist(loop, peel, peel_list);
3883 
3884   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3885 
3886   // For future check for too many new phis
3887   uint old_phi_cnt = 0;
3888   for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3889     Node* use = head->fast_out(j);
3890     if (use->is_Phi()) old_phi_cnt++;
3891   }
3892 
3893 #ifndef PRODUCT
3894   if (TracePartialPeeling) {
3895     tty->print_cr("\npeeled list");
3896   }
3897 #endif
3898 
3899   // Evacuate nodes in peel region into the not_peeled region if possible
3900   bool too_many_clones = false;
3901   uint new_phi_cnt = 0;
3902   uint cloned_for_outside_use = 0;
3903   for (uint i = 0; i < peel_list.size();) {
3904     Node* n = peel_list.at(i);
3905 #ifndef PRODUCT
3906   if (TracePartialPeeling) n->dump();
3907 #endif
3908     bool incr = true;
3909     if (!n->is_CFG()) {
3910       if (has_use_in_set(n, not_peel)) {
3911         // If not used internal to the peeled region,
3912         // move "n" from peeled to not_peeled region.
3913         if (!has_use_internal_to_set(n, peel, loop)) {
3914           // if not pinned and not a load (which maybe anti-dependent on a store)
3915           // and not a CMove (Matcher expects only bool->cmove).
3916           if (n->in(0) == nullptr && !n->is_Load() && !n->is_CMove()) {
3917             int new_clones = clone_for_use_outside_loop(loop, n, worklist);
3918             if (C->failing()) return false;
3919             if (new_clones == -1) {
3920               too_many_clones = true;
3921               break;
3922             }
3923             cloned_for_outside_use += new_clones;
3924             sink_list.push(n);
3925             peel.remove(n->_idx);
3926             not_peel.set(n->_idx);
3927             peel_list.remove(i);
3928             incr = false;
3929 #ifndef PRODUCT
3930             if (TracePartialPeeling) {
3931               tty->print_cr("sink to not_peeled region: %d newbb: %d",
3932                             n->_idx, get_ctrl(n)->_idx);
3933             }
3934 #endif
3935           }
3936         } else {
3937           // Otherwise check for special def-use cases that span
3938           // the peel/not_peel boundary such as bool->if
3939           clone_for_special_use_inside_loop(loop, n, not_peel, sink_list, worklist);
3940           new_phi_cnt++;
3941         }
3942       }
3943     }
3944     if (incr) i++;
3945   }
3946 
3947   estimate += cloned_for_outside_use + new_phi_cnt;
3948   bool exceed_node_budget = !may_require_nodes(estimate);
3949   bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;
3950 
3951   if (too_many_clones || exceed_node_budget || exceed_phi_limit) {
3952 #ifndef PRODUCT
3953     if (TracePartialPeeling && exceed_phi_limit) {
3954       tty->print_cr("\nToo many new phis: %d  old %d new cmpi: %c",
3955                     new_phi_cnt, old_phi_cnt, new_peel_if != nullptr?'T':'F');
3956     }
3957 #endif
3958     if (new_peel_if != nullptr) {
3959       remove_cmpi_loop_exit(new_peel_if, loop);
3960     }
3961     // Inhibit more partial peeling on this loop
3962     assert(!head->is_partial_peel_loop(), "not partial peeled");
3963     head->mark_partial_peel_failed();
3964     if (cloned_for_outside_use > 0) {
3965       // Terminate this round of loop opts because
3966       // the graph outside this loop was changed.
3967       C->set_major_progress();
3968       return true;
3969     }
3970     return false;
3971   }
3972 
3973   // Step 3: clone loop, retarget control, and insert new phis
3974 
3975   // Create new loop head for new phis and to hang
3976   // the nodes being moved (sinked) from the peel region.
3977   LoopNode* new_head = new LoopNode(last_peel, last_peel);
3978   new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3979   _igvn.register_new_node_with_optimizer(new_head);
3980   assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3981   _igvn.replace_input_of(first_not_peeled, 0, new_head);
3982   set_loop(new_head, loop);
3983   loop->_body.push(new_head);
3984   not_peel.set(new_head->_idx);
3985   set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3986   set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
3987 
3988   while (sink_list.size() > 0) {
3989     Node* n = sink_list.pop();
3990     set_ctrl(n, new_head);
3991   }
3992 
3993   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3994 
3995   clone_loop(loop, old_new, dd, IgnoreStripMined);
3996 
3997   const uint clone_exit_idx = 1;
3998   const uint orig_exit_idx  = 2;
3999   assert(is_valid_clone_loop_form(loop, peel_list, orig_exit_idx, clone_exit_idx), "bad clone loop");
4000 
4001   Node* head_clone             = old_new[head->_idx];
4002   LoopNode* new_head_clone     = old_new[new_head->_idx]->as_Loop();
4003   Node* orig_tail_clone        = head_clone->in(2);
4004 
4005   // Add phi if "def" node is in peel set and "use" is not
4006 
4007   for (uint i = 0; i < peel_list.size(); i++) {
4008     Node *def  = peel_list.at(i);
4009     if (!def->is_CFG()) {
4010       for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
4011         Node *use = def->fast_out(j);
4012         if (has_node(use) && use->in(0) != C->top() &&
4013             (!peel.test(use->_idx) ||
4014              (use->is_Phi() && use->in(0) == head)) ) {
4015           worklist.push(use);
4016         }
4017       }
4018       while( worklist.size() ) {
4019         Node *use = worklist.pop();
4020         for (uint j = 1; j < use->req(); j++) {
4021           Node* n = use->in(j);
4022           if (n == def) {
4023 
4024             // "def" is in peel set, "use" is not in peel set
4025             // or "use" is in the entry boundary (a phi) of the peel set
4026 
4027             Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
4028 
4029             if ( loop->is_member(get_loop( use_c )) ) {
4030               // use is in loop
4031               if (old_new[use->_idx] != nullptr) { // null for dead code
4032                 Node* use_clone = old_new[use->_idx];
4033                 _igvn.replace_input_of(use, j, C->top());
4034                 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
4035               }
4036             } else {
4037               assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
4038               // use is not in the loop, check if the live range includes the cut
4039               Node* lp_if = use_c->in(orig_exit_idx)->in(0);
4040               if (not_peel.test(lp_if->_idx)) {
4041                 assert(j == orig_exit_idx, "use from original loop");
4042                 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
4043               }
4044             }
4045           }
4046         }
4047       }
4048     }
4049   }
4050 
4051   // Step 3b: retarget control
4052 
4053   // Redirect control to the new loop head if a cloned node in
4054   // the not_peeled region has control that points into the peeled region.
4055   // This necessary because the cloned peeled region will be outside
4056   // the loop.
4057   //                            from    to
4058   //          cloned-peeled    <---+
4059   //    new_head_clone:            |    <--+
4060   //          cloned-not_peeled  in(0)    in(0)
4061   //          orig-peeled
4062 
4063   for (uint i = 0; i < loop->_body.size(); i++) {
4064     Node *n = loop->_body.at(i);
4065     if (!n->is_CFG()           && n->in(0) != nullptr        &&
4066         not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
4067       Node* n_clone = old_new[n->_idx];
4068       if (n_clone->depends_only_on_test()) {
4069         // Pin array access nodes: control is updated here to the loop head. If, after some transformations, the
4070         // backedge is removed, an array load could become dependent on a condition that's not a range check for that
4071         // access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
4072         // floating above its range check.
4073         Node* pinned_clone = n_clone->pin_array_access_node();
4074         if (pinned_clone != nullptr) {
4075           register_new_node_with_ctrl_of(pinned_clone, n_clone);
4076           old_new.map(n->_idx, pinned_clone);
4077           _igvn.replace_node(n_clone, pinned_clone);
4078           n_clone = pinned_clone;
4079         }
4080       }
4081       _igvn.replace_input_of(n_clone, 0, new_head_clone);
4082     }
4083   }
4084 
4085   // Backedge of the surviving new_head (the clone) is original last_peel
4086   _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
4087 
4088   // Cut first node in original not_peel set
4089   _igvn.rehash_node_delayed(new_head);                     // Multiple edge updates:
4090   new_head->set_req(LoopNode::EntryControl,    C->top());  //   use rehash_node_delayed / set_req instead of
4091   new_head->set_req(LoopNode::LoopBackControl, C->top());  //   multiple replace_input_of calls
4092 
4093   // Copy head_clone back-branch info to original head
4094   // and remove original head's loop entry and
4095   // clone head's back-branch
4096   _igvn.rehash_node_delayed(head); // Multiple edge updates
4097   head->set_req(LoopNode::EntryControl,    head_clone->in(LoopNode::LoopBackControl));
4098   head->set_req(LoopNode::LoopBackControl, C->top());
4099   _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
4100 
4101   // Similarly modify the phis
4102   for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
4103     Node* use = head->fast_out(k);
4104     if (use->is_Phi() && use->outcnt() > 0) {
4105       Node* use_clone = old_new[use->_idx];
4106       _igvn.rehash_node_delayed(use); // Multiple edge updates
4107       use->set_req(LoopNode::EntryControl,    use_clone->in(LoopNode::LoopBackControl));
4108       use->set_req(LoopNode::LoopBackControl, C->top());
4109       _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
4110     }
4111   }
4112 
4113   // Step 4: update dominator tree and dominator depth
4114 
4115   set_idom(head, orig_tail_clone, dd);
4116   recompute_dom_depth();
4117 
4118   // Inhibit more partial peeling on this loop
4119   new_head_clone->set_partial_peel_loop();
4120   C->set_major_progress();
4121   loop->record_for_igvn();
4122 
4123 #ifndef PRODUCT
4124   if (TracePartialPeeling) {
4125     tty->print_cr("\nafter partial peel one iteration");
4126     Node_List wl;
4127     Node* t = last_peel;
4128     while (true) {
4129       wl.push(t);
4130       if (t == head_clone) break;
4131       t = idom(t);
4132     }
4133     while (wl.size() > 0) {
4134       Node* tt = wl.pop();
4135       if (tt == head) tty->print_cr("orig head");
4136       else if (tt == new_head_clone) tty->print_cr("new head");
4137       else if (tt == head_clone) tty->print_cr("clone head");
4138       tt->dump();
4139     }
4140   }
4141 #endif
4142 
4143   C->print_method(PHASE_AFTER_PARTIAL_PEELING, 4, new_head_clone);
4144 
4145   return true;
4146 }
4147 
4148 // Transform:
4149 //
4150 // loop<-----------------+
4151 //  |                    |
4152 // stmt1 stmt2 .. stmtn  |
4153 //  |     |        |     |
4154 //  \     |       /      |
4155 //    v   v     v        |
4156 //       region          |
4157 //         |             |
4158 //     shared_stmt       |
4159 //         |             |
4160 //         v             |
4161 //         if            |
4162 //         / \           |
4163 //        |   -----------+
4164 //        v
4165 //
4166 // into:
4167 //
4168 //    loop<-------------------+
4169 //     |                      |
4170 //     v                      |
4171 // +->loop                    |
4172 // |   |                      |
4173 // |  stmt1 stmt2 .. stmtn    |
4174 // |   |     |        |       |
4175 // |   |      \       /       |
4176 // |   |       v     v        |
4177 // |   |        region1       |
4178 // |   |           |          |
4179 // |  shared_stmt shared_stmt |
4180 // |   |           |          |
4181 // |   v           v          |
4182 // |   if          if         |
4183 // |   /\          / \        |
4184 // +--   |         |   -------+
4185 //       \         /
4186 //        v       v
4187 //         region2
4188 //
4189 // (region2 is shown to merge mirrored projections of the loop exit
4190 // ifs to make the diagram clearer but they really merge the same
4191 // projection)
4192 //
4193 // Conditions for this transformation to trigger:
4194 // - the path through stmt1 is frequent enough
4195 // - the inner loop will be turned into a counted loop after transformation
4196 bool PhaseIdealLoop::duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new) {
4197   if (!DuplicateBackedge) {
4198     return false;
4199   }
4200   assert(!loop->_head->is_CountedLoop() || StressDuplicateBackedge, "Non-counted loop only");
4201   if (!loop->_head->is_Loop()) {
4202     return false;
4203   }
4204 
4205   uint estimate = loop->est_loop_clone_sz(1);
4206   if (exceeding_node_budget(estimate)) {
4207     return false;
4208   }
4209 
4210   LoopNode *head = loop->_head->as_Loop();
4211 
4212   Node* region = nullptr;
4213   IfNode* exit_test = nullptr;
4214   uint inner;
4215   float f;
4216   if (StressDuplicateBackedge) {
4217     if (head->is_strip_mined()) {
4218       return false;
4219     }
4220     Node* c = head->in(LoopNode::LoopBackControl);
4221 
4222     while (c != head) {
4223       if (c->is_Region()) {
4224         region = c;
4225       }
4226       c = idom(c);
4227     }
4228 
4229     if (region == nullptr) {
4230       return false;
4231     }
4232 
4233     inner = 1;
4234   } else {
4235     // Is the shape of the loop that of a counted loop...
4236     Node* back_control = loop_exit_control(head, loop);
4237     if (back_control == nullptr) {
4238       return false;
4239     }
4240 
4241     BoolTest::mask bt = BoolTest::illegal;
4242     float cl_prob = 0;
4243     Node* incr = nullptr;
4244     Node* limit = nullptr;
4245     Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob);
4246     if (cmp == nullptr || cmp->Opcode() != Op_CmpI) {
4247       return false;
4248     }
4249 
4250     // With an extra phi for the candidate iv?
4251     // Or the region node is the loop head
4252     if (!incr->is_Phi() || incr->in(0) == head) {
4253       return false;
4254     }
4255 
4256     PathFrequency pf(head, this);
4257     region = incr->in(0);
4258 
4259     // Go over all paths for the extra phi's region and see if that
4260     // path is frequent enough and would match the expected iv shape
4261     // if the extra phi is removed
4262     inner = 0;
4263     for (uint i = 1; i < incr->req(); ++i) {
4264       Node* in = incr->in(i);
4265       Node* trunc1 = nullptr;
4266       Node* trunc2 = nullptr;
4267       const TypeInteger* iv_trunc_t = nullptr;
4268       Node* orig_in = in;
4269       if (!(in = CountedLoopNode::match_incr_with_optional_truncation(in, &trunc1, &trunc2, &iv_trunc_t, T_INT))) {
4270         continue;
4271       }
4272       assert(in->Opcode() == Op_AddI, "wrong increment code");
4273       Node* xphi = nullptr;
4274       Node* stride = loop_iv_stride(in, loop, xphi);
4275 
4276       if (stride == nullptr) {
4277         continue;
4278       }
4279 
4280       PhiNode* phi = loop_iv_phi(xphi, nullptr, head, loop);
4281       if (phi == nullptr ||
4282           (trunc1 == nullptr && phi->in(LoopNode::LoopBackControl) != incr) ||
4283           (trunc1 != nullptr && phi->in(LoopNode::LoopBackControl) != trunc1)) {
4284         return false;
4285       }
4286 
4287       f = pf.to(region->in(i));
4288       if (f > 0.5) {
4289         inner = i;
4290         break;
4291       }
4292     }
4293 
4294     if (inner == 0) {
4295       return false;
4296     }
4297 
4298     exit_test = back_control->in(0)->as_If();
4299   }
4300 
4301   if (idom(region)->is_Catch()) {
4302     return false;
4303   }
4304 
4305   // Collect all control nodes that need to be cloned (shared_stmt in the diagram)
4306   Unique_Node_List wq;
4307   wq.push(head->in(LoopNode::LoopBackControl));
4308   for (uint i = 0; i < wq.size(); i++) {
4309     Node* c = wq.at(i);
4310     assert(get_loop(c) == loop, "not in the right loop?");
4311     if (c->is_Region()) {
4312       if (c != region) {
4313         for (uint j = 1; j < c->req(); ++j) {
4314           wq.push(c->in(j));
4315         }
4316       }
4317     } else {
4318       wq.push(c->in(0));
4319     }
4320     assert(!is_strict_dominator(c, region), "shouldn't go above region");
4321   }
4322 
4323   Node* region_dom = idom(region);
4324 
4325   // Can't do the transformation if this would cause a membar pair to
4326   // be split
4327   for (uint i = 0; i < wq.size(); i++) {
4328     Node* c = wq.at(i);
4329     if (c->is_MemBar() && (c->as_MemBar()->trailing_store() || c->as_MemBar()->trailing_load_store())) {
4330       assert(c->as_MemBar()->leading_membar()->trailing_membar() == c, "bad membar pair");
4331       if (!wq.member(c->as_MemBar()->leading_membar())) {
4332         return false;
4333       }
4334     }
4335   }
4336 
4337   // Collect data nodes that need to be clones as well
4338   int dd = dom_depth(head);
4339 
4340   for (uint i = 0; i < loop->_body.size(); ++i) {
4341     Node* n = loop->_body.at(i);
4342     if (has_ctrl(n)) {
4343       Node* c = get_ctrl(n);
4344       if (wq.member(c)) {
4345         wq.push(n);
4346       }
4347     } else {
4348       set_idom(n, idom(n), dd);
4349     }
4350   }
4351 
4352   // clone shared_stmt
4353   clone_loop_body(wq, old_new, nullptr);
4354 
4355   Node* region_clone = old_new[region->_idx];
4356   region_clone->set_req(inner, C->top());
4357   set_idom(region, region->in(inner), dd);
4358 
4359   // Prepare the outer loop
4360   Node* outer_head = new LoopNode(head->in(LoopNode::EntryControl), old_new[head->in(LoopNode::LoopBackControl)->_idx]);
4361   register_control(outer_head, loop->_parent, outer_head->in(LoopNode::EntryControl));
4362   _igvn.replace_input_of(head, LoopNode::EntryControl, outer_head);
4363   set_idom(head, outer_head, dd);
4364 
4365   fix_body_edges(wq, loop, old_new, dd, loop->_parent, true);
4366 
4367   // Make one of the shared_stmt copies only reachable from stmt1, the
4368   // other only from stmt2..stmtn.
4369   Node* dom = nullptr;
4370   for (uint i = 1; i < region->req(); ++i) {
4371     if (i != inner) {
4372       _igvn.replace_input_of(region, i, C->top());
4373     }
4374     Node* in = region_clone->in(i);
4375     if (in->is_top()) {
4376       continue;
4377     }
4378     if (dom == nullptr) {
4379       dom = in;
4380     } else {
4381       dom = dom_lca(dom, in);
4382     }
4383   }
4384 
4385   set_idom(region_clone, dom, dd);
4386 
4387   // Set up the outer loop
4388   for (uint i = 0; i < head->outcnt(); i++) {
4389     Node* u = head->raw_out(i);
4390     if (u->is_Phi()) {
4391       Node* outer_phi = u->clone();
4392       outer_phi->set_req(0, outer_head);
4393       Node* backedge = old_new[u->in(LoopNode::LoopBackControl)->_idx];
4394       if (backedge == nullptr) {
4395         backedge = u->in(LoopNode::LoopBackControl);
4396       }
4397       outer_phi->set_req(LoopNode::LoopBackControl, backedge);
4398       register_new_node(outer_phi, outer_head);
4399       _igvn.replace_input_of(u, LoopNode::EntryControl, outer_phi);
4400     }
4401   }
4402 
4403   // create control and data nodes for out of loop uses (including region2)
4404   Node_List worklist;
4405   uint new_counter = C->unique();
4406   fix_ctrl_uses(wq, loop, old_new, ControlAroundStripMined, outer_head, nullptr, worklist);
4407 
4408   Node_List *split_if_set = nullptr;
4409   Node_List *split_bool_set = nullptr;
4410   Node_List *split_cex_set = nullptr;
4411   fix_data_uses(wq, loop, ControlAroundStripMined, loop->skip_strip_mined(), new_counter, old_new, worklist,
4412                 split_if_set, split_bool_set, split_cex_set);
4413 
4414   finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
4415 
4416   if (exit_test != nullptr) {
4417     float cnt = exit_test->_fcnt;
4418     if (cnt != COUNT_UNKNOWN) {
4419       exit_test->_fcnt = cnt * f;
4420       old_new[exit_test->_idx]->as_If()->_fcnt = cnt * (1 - f);
4421     }
4422   }
4423 
4424   C->set_major_progress();
4425 
4426   return true;
4427 }
4428 
4429 // AutoVectorize the loop: replace scalar ops with vector ops.
4430 PhaseIdealLoop::AutoVectorizeStatus
4431 PhaseIdealLoop::auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared) {
4432   // Counted loop only
4433   if (!lpt->is_counted()) {
4434     return AutoVectorizeStatus::Impossible;
4435   }
4436 
4437   // Main-loop only
4438   CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4439   if (!cl->is_main_loop()) {
4440     return AutoVectorizeStatus::Impossible;
4441   }
4442 
4443   VLoop vloop(lpt, false);
4444   if (!vloop.check_preconditions()) {
4445     return AutoVectorizeStatus::TriedAndFailed;
4446   }
4447 
4448   // Ensure the shared data is cleared before each use
4449   vshared.clear();
4450 
4451   const VLoopAnalyzer vloop_analyzer(vloop, vshared);
4452   if (!vloop_analyzer.success()) {
4453     return AutoVectorizeStatus::TriedAndFailed;
4454   }
4455 
4456   SuperWord sw(vloop_analyzer);
4457   if (!sw.transform_loop()) {
4458     return AutoVectorizeStatus::TriedAndFailed;
4459   }
4460 
4461   return AutoVectorizeStatus::Success;
4462 }
4463 
4464 // Just before insert_pre_post_loops, we can multiversion the loop:
4465 //
4466 //              multiversion_if
4467 //               |       |
4468 //         fast_loop   slow_loop
4469 //
4470 // In the fast_loop we can make speculative assumptions, and put the
4471 // conditions into the multiversion_if. If the conditions hold at runtime,
4472 // we enter the fast_loop, if the conditions fail, we take the slow_loop
4473 // instead which does not make any of the speculative assumptions.
4474 //
4475 // Note: we only multiversion the loop if the loop does not have any
4476 //       auto vectorization check Predicate. If we have that predicate,
4477 //       then we can simply add the speculative assumption checks to
4478 //       that Predicate. This means we do not need to duplicate the
4479 //       loop - we have a smaller graph and save compile time. Should
4480 //       the conditions ever fail, then we deopt / trap at the Predicate
4481 //       and recompile without that Predicate. At that point we will
4482 //       multiversion the loop, so that we can still have speculative
4483 //       runtime checks.
4484 //
4485 // We perform the multiversioning when the loop is still in its single
4486 // iteration form, even before we insert pre and post loops. This makes
4487 // the cloning much simpler. However, this means that both the fast
4488 // and the slow loop have to be optimized independently (adding pre
4489 // and post loops, unrolling the main loop, auto-vectorize etc.). And
4490 // we may end up not needing any speculative assumptions in the fast_loop
4491 // and then rejecting the slow_loop by constant folding the multiversion_if.
4492 //
4493 // Therefore, we "delay" the optimization of the slow_loop until we add
4494 // at least one speculative assumption for the fast_loop. If we never
4495 // add such a speculative runtime check, the OpaqueMultiversioningNode
4496 // of the multiversion_if constant folds to true after loop opts, and the
4497 // multiversion_if folds away the "delayed" slow_loop. If we add any
4498 // speculative assumption, then we notify the OpaqueMultiversioningNode
4499 // with "notify_slow_loop_that_it_can_resume_optimizations".
4500 //
4501 // Note: new runtime checks can be added to the multiversion_if with
4502 //       PhaseIdealLoop::create_new_if_for_multiversion
4503 void PhaseIdealLoop::maybe_multiversion_for_auto_vectorization_runtime_checks(IdealLoopTree* lpt, Node_List& old_new) {
4504   CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4505   LoopNode* outer_loop = cl->skip_strip_mined();
4506   Node* entry = outer_loop->in(LoopNode::EntryControl);
4507 
4508   // Check we have multiversioning enabled, and are not already multiversioned.
4509   if (!LoopMultiversioning || cl->is_multiversion()) { return; }
4510 
4511   // Check that we do not have a parse-predicate where we can add the runtime checks
4512   // during auto-vectorization.
4513   const Predicates predicates(entry);
4514   const PredicateBlock* predicate_block = predicates.auto_vectorization_check_block();
4515   if (predicate_block->has_parse_predicate()) { return; }
4516 
4517   // Check node budget.
4518   uint estimate = lpt->est_loop_clone_sz(2);
4519   if (!may_require_nodes(estimate)) { return; }
4520 
4521   do_multiversioning(lpt, old_new);
4522 }
4523 
4524 // Returns true if the Reduction node is unordered.
4525 static bool is_unordered_reduction(Node* n) {
4526   return n->is_Reduction() && !n->as_Reduction()->requires_strict_order();
4527 }
4528 
4529 // Having ReductionNodes in the loop is expensive. They need to recursively
4530 // fold together the vector values, for every vectorized loop iteration. If
4531 // we encounter the following pattern, we can vector accumulate the values
4532 // inside the loop, and only have a single UnorderedReduction after the loop.
4533 //
4534 // Note: UnorderedReduction represents a ReductionNode which does not require
4535 // calculating in strict order.
4536 //
4537 // CountedLoop     init
4538 //          |        |
4539 //          +------+ | +-----------------------+
4540 //                 | | |                       |
4541 //                PhiNode (s)                  |
4542 //                  |                          |
4543 //                  |          Vector          |
4544 //                  |            |             |
4545 //               UnorderedReduction (first_ur) |
4546 //                  |                          |
4547 //                 ...         Vector          |
4548 //                  |            |             |
4549 //               UnorderedReduction (last_ur)  |
4550 //                       |                     |
4551 //                       +---------------------+
4552 //
4553 // We patch the graph to look like this:
4554 //
4555 // CountedLoop   identity_vector
4556 //         |         |
4557 //         +-------+ | +---------------+
4558 //                 | | |               |
4559 //                PhiNode (v)          |
4560 //                   |                 |
4561 //                   |         Vector  |
4562 //                   |           |     |
4563 //                 VectorAccumulator   |
4564 //                   |                 |
4565 //                  ...        Vector  |
4566 //                   |           |     |
4567 //      init       VectorAccumulator   |
4568 //        |          |     |           |
4569 //     UnorderedReduction  +-----------+
4570 //
4571 // We turned the scalar (s) Phi into a vectorized one (v). In the loop, we
4572 // use vector_accumulators, which do the same reductions, but only element
4573 // wise. This is a single operation per vector_accumulator, rather than many
4574 // for a UnorderedReduction. We can then reduce the last vector_accumulator
4575 // after the loop, and also reduce the init value into it.
4576 //
4577 // We can not do this with all reductions. Some reductions do not allow the
4578 // reordering of operations (for example float addition/multiplication require
4579 // strict order).
4580 void PhaseIdealLoop::move_unordered_reduction_out_of_loop(IdealLoopTree* loop) {
4581   assert(!C->major_progress() && loop->is_counted() && loop->is_innermost(), "sanity");
4582 
4583   // Find all Phi nodes with an unordered Reduction on backedge.
4584   CountedLoopNode* cl = loop->_head->as_CountedLoop();
4585   for (DUIterator_Fast jmax, j = cl->fast_outs(jmax); j < jmax; j++) {
4586     Node* phi = cl->fast_out(j);
4587     // We have a phi with a single use, and an unordered Reduction on the backedge.
4588     if (!phi->is_Phi() || phi->outcnt() != 1 || !is_unordered_reduction(phi->in(2))) {
4589       continue;
4590     }
4591 
4592     ReductionNode* last_ur = phi->in(2)->as_Reduction();
4593     assert(!last_ur->requires_strict_order(), "must be");
4594 
4595     // Determine types
4596     const TypeVect* vec_t = last_ur->vect_type();
4597     uint vector_length    = vec_t->length();
4598     BasicType bt          = vec_t->element_basic_type();
4599 
4600     // Convert opcode from vector-reduction -> scalar -> normal-vector-op
4601     const int sopc        = VectorNode::scalar_opcode(last_ur->Opcode(), bt);
4602     const int vopc        = VectorNode::opcode(sopc, bt);
4603     if (!Matcher::match_rule_supported_vector(vopc, vector_length, bt)) {
4604         DEBUG_ONLY( last_ur->dump(); )
4605         assert(false, "do not have normal vector op for this reduction");
4606         continue; // not implemented -> fails
4607     }
4608 
4609     // Traverse up the chain of unordered Reductions, checking that it loops back to
4610     // the phi. Check that all unordered Reductions only have a single use, except for
4611     // the last (last_ur), which only has phi as a use in the loop, and all other uses
4612     // are outside the loop.
4613     ReductionNode* current = last_ur;
4614     ReductionNode* first_ur = nullptr;
4615     while (true) {
4616       assert(!current->requires_strict_order(), "sanity");
4617 
4618       // Expect no ctrl and a vector_input from within the loop.
4619       Node* ctrl = current->in(0);
4620       Node* vector_input = current->in(2);
4621       if (ctrl != nullptr || get_ctrl(vector_input) != cl) {
4622         DEBUG_ONLY( current->dump(1); )
4623         assert(false, "reduction has ctrl or bad vector_input");
4624         break; // Chain traversal fails.
4625       }
4626 
4627       assert(current->vect_type() != nullptr, "must have vector type");
4628       if (current->vect_type() != last_ur->vect_type()) {
4629         // Reductions do not have the same vector type (length and element type).
4630         break; // Chain traversal fails.
4631       }
4632 
4633       // Expect single use of an unordered Reduction, except for last_ur.
4634       if (current == last_ur) {
4635         // Expect all uses to be outside the loop, except phi.
4636         for (DUIterator_Fast kmax, k = current->fast_outs(kmax); k < kmax; k++) {
4637           Node* use = current->fast_out(k);
4638           if (use != phi && ctrl_or_self(use) == cl) {
4639             DEBUG_ONLY( current->dump(-1); )
4640             assert(false, "reduction has use inside loop");
4641             // Should not be allowed by SuperWord::mark_reductions
4642             return; // bail out of optimization
4643           }
4644         }
4645       } else {
4646         if (current->outcnt() != 1) {
4647           break; // Chain traversal fails.
4648         }
4649       }
4650 
4651       // Expect another unordered Reduction or phi as the scalar input.
4652       Node* scalar_input = current->in(1);
4653       if (is_unordered_reduction(scalar_input) &&
4654           scalar_input->Opcode() == current->Opcode()) {
4655         // Move up the unordered Reduction chain.
4656         current = scalar_input->as_Reduction();
4657         assert(!current->requires_strict_order(), "must be");
4658       } else if (scalar_input == phi) {
4659         // Chain terminates at phi.
4660         first_ur = current;
4661         current = nullptr;
4662         break; // Success.
4663       } else {
4664         // scalar_input is neither phi nor a matching reduction
4665         // Can for example be scalar reduction when we have
4666         // partial vectorization.
4667         break; // Chain traversal fails.
4668       }
4669     }
4670     if (current != nullptr) {
4671       // Chain traversal was not successful.
4672       continue;
4673     }
4674     assert(first_ur != nullptr, "must have successfully terminated chain traversal");
4675 
4676     Node* identity_scalar = ReductionNode::make_identity_con_scalar(_igvn, sopc, bt);
4677     set_root_as_ctrl(identity_scalar);
4678     VectorNode* identity_vector = VectorNode::scalar2vector(identity_scalar, vector_length, bt);
4679     register_new_node(identity_vector, C->root());
4680     assert(vec_t == identity_vector->vect_type(), "matching vector type");
4681     VectorNode::trace_new_vector(identity_vector, "Unordered Reduction");
4682 
4683     // Turn the scalar phi into a vector phi.
4684     _igvn.rehash_node_delayed(phi);
4685     Node* init = phi->in(1); // Remember init before replacing it.
4686     phi->set_req_X(1, identity_vector, &_igvn);
4687     phi->as_Type()->set_type(vec_t);
4688     _igvn.set_type(phi, vec_t);
4689 
4690     // Traverse down the chain of unordered Reductions, and replace them with vector_accumulators.
4691     current = first_ur;
4692     while (true) {
4693       // Create vector_accumulator to replace current.
4694       Node* last_vector_accumulator = current->in(1);
4695       Node* vector_input            = current->in(2);
4696       VectorNode* vector_accumulator = VectorNode::make(vopc, last_vector_accumulator, vector_input, vec_t);
4697       register_new_node(vector_accumulator, cl);
4698       _igvn.replace_node(current, vector_accumulator);
4699       VectorNode::trace_new_vector(vector_accumulator, "Unordered Reduction");
4700       if (current == last_ur) {
4701         break;
4702       }
4703       current = vector_accumulator->unique_out()->as_Reduction();
4704       assert(!current->requires_strict_order(), "must be");
4705     }
4706 
4707     // Create post-loop reduction.
4708     Node* last_accumulator = phi->in(2);
4709     Node* post_loop_reduction = ReductionNode::make(sopc, nullptr, init, last_accumulator, bt);
4710 
4711     // Take over uses of last_accumulator that are not in the loop.
4712     for (DUIterator i = last_accumulator->outs(); last_accumulator->has_out(i); i++) {
4713       Node* use = last_accumulator->out(i);
4714       if (use != phi && use != post_loop_reduction) {
4715         assert(ctrl_or_self(use) != cl, "use must be outside loop");
4716         use->replace_edge(last_accumulator, post_loop_reduction,  &_igvn);
4717         --i;
4718       }
4719     }
4720     register_new_node(post_loop_reduction, get_late_ctrl(post_loop_reduction, cl));
4721     VectorNode::trace_new_vector(post_loop_reduction, "Unordered Reduction");
4722 
4723     assert(last_accumulator->outcnt() == 2, "last_accumulator has 2 uses: phi and post_loop_reduction");
4724     assert(post_loop_reduction->outcnt() > 0, "should have taken over all non loop uses of last_accumulator");
4725     assert(phi->outcnt() == 1, "accumulator is the only use of phi");
4726   }
4727 }
4728 
4729 void DataNodeGraph::clone_data_nodes(Node* new_ctrl) {
4730   for (uint i = 0; i < _data_nodes.size(); i++) {
4731     clone(_data_nodes[i], new_ctrl);
4732   }
4733 }
4734 
4735 // Clone the given node and set it up properly. Set 'new_ctrl' as ctrl.
4736 void DataNodeGraph::clone(Node* node, Node* new_ctrl) {
4737   Node* clone = node->clone();
4738   _phase->igvn().register_new_node_with_optimizer(clone);
4739   _orig_to_new.put(node, clone);
4740   _phase->set_ctrl(clone, new_ctrl);
4741   if (node->is_CastII()) {
4742     clone->set_req(0, new_ctrl);
4743   }
4744 }
4745 
4746 // Rewire the data inputs of all (unprocessed) cloned nodes, whose inputs are still pointing to the same inputs as their
4747 // corresponding orig nodes, to the newly cloned inputs to create a separate cloned graph.
4748 void DataNodeGraph::rewire_clones_to_cloned_inputs() {
4749   _orig_to_new.iterate_all([&](Node* node, Node* clone) {
4750     for (uint i = 1; i < node->req(); i++) {
4751       Node** cloned_input = _orig_to_new.get(node->in(i));
4752       if (cloned_input != nullptr) {
4753         // Input was also cloned -> rewire clone to the cloned input.
4754         _phase->igvn().replace_input_of(clone, i, *cloned_input);
4755       }
4756     }
4757   });
4758 }
4759 
4760 // Clone all non-OpaqueLoop* nodes and apply the provided transformation strategy for OpaqueLoop* nodes.
4761 // Set 'new_ctrl' as ctrl for all cloned non-OpaqueLoop* nodes.
4762 void DataNodeGraph::clone_data_nodes_and_transform_opaque_loop_nodes(
4763     const TransformStrategyForOpaqueLoopNodes& transform_strategy,
4764     Node* new_ctrl) {
4765   for (uint i = 0; i < _data_nodes.size(); i++) {
4766     Node* data_node = _data_nodes[i];
4767     if (data_node->is_Opaque1()) {
4768       transform_opaque_node(transform_strategy, data_node);
4769     } else {
4770       clone(data_node, new_ctrl);
4771     }
4772   }
4773 }
4774 
4775 void DataNodeGraph::transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node) {
4776   Node* transformed_node;
4777   if (node->is_OpaqueLoopInit()) {
4778     transformed_node = transform_strategy.transform_opaque_init(node->as_OpaqueLoopInit());
4779   } else {
4780     assert(node->is_OpaqueLoopStride(), "must be OpaqueLoopStrideNode");
4781     transformed_node = transform_strategy.transform_opaque_stride(node->as_OpaqueLoopStride());
4782   }
4783   // Add an orig->new mapping to correctly update the inputs of the copied graph in rewire_clones_to_cloned_inputs().
4784   _orig_to_new.put(node, transformed_node);
4785 }