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   assert(bol->Opcode() == Op_Bool, "Unexpected node");
 795   int cmp_op = bol->in(1)->Opcode();
 796   if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode
 797     return nullptr;
 798   }
 799   // It is expensive to generate flags from a float compare.
 800   // Avoid duplicated float compare.
 801   if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return nullptr;
 802 
 803   float infrequent_prob = PROB_UNLIKELY_MAG(3);
 804   // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
 805   if (used_inside_loop) {
 806     if (cost >= ConditionalMoveLimit) return nullptr; // Too much goo
 807 
 808     // BlockLayoutByFrequency optimization moves infrequent branch
 809     // from hot path. No point in CMOV'ing in such case (110 is used
 810     // instead of 100 to take into account not exactness of float value).
 811     if (BlockLayoutByFrequency) {
 812       infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
 813     }
 814   }
 815   // Check for highly predictable branch.  No point in CMOV'ing if
 816   // we are going to predict accurately all the time.
 817   if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
 818     //keep going
 819   } else if (iff->_prob < infrequent_prob ||
 820       iff->_prob > (1.0f - infrequent_prob))
 821     return nullptr;
 822 
 823   // --------------
 824   // Now replace all Phis with CMOV's
 825   Node *cmov_ctrl = iff->in(0);
 826   uint flip = (lp->Opcode() == Op_IfTrue);
 827   Node_List wq;
 828   while (1) {
 829     PhiNode* phi = nullptr;
 830     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 831       Node *out = region->fast_out(i);
 832       if (out->is_Phi()) {
 833         phi = out->as_Phi();
 834         break;
 835       }
 836     }
 837     if (phi == nullptr || _igvn.type(phi) == Type::TOP) {
 838       break;
 839     }
 840     if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
 841     // Move speculative ops
 842     wq.push(phi);
 843     while (wq.size() > 0) {
 844       Node *n = wq.pop();
 845       for (uint j = 1; j < n->req(); j++) {
 846         Node* m = n->in(j);
 847         if (m != nullptr && !is_dominator(get_ctrl(m), cmov_ctrl)) {
 848 #ifndef PRODUCT
 849           if (PrintOpto && VerifyLoopOptimizations) {
 850             tty->print("  speculate: ");
 851             m->dump();
 852           }
 853 #endif
 854           set_ctrl(m, cmov_ctrl);
 855           wq.push(m);
 856         }
 857       }
 858     }
 859     Node* cmov = CMoveNode::make(iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
 860     register_new_node(cmov, cmov_ctrl);
 861     _igvn.replace_node(phi, cmov);
 862 #ifndef PRODUCT
 863     if (TraceLoopOpts) {
 864       tty->print("CMOV  ");
 865       r_loop->dump_head();
 866       if (Verbose) {
 867         bol->in(1)->dump(1);
 868         cmov->dump(1);
 869       }
 870     }
 871     DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
 872 #endif
 873   }
 874 
 875   // The useless CFG diamond will fold up later; see the optimization in
 876   // RegionNode::Ideal.
 877   _igvn._worklist.push(region);
 878 
 879   return iff->in(1);
 880 }
 881 
 882 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
 883   for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
 884     Node* u = m->fast_out(i);
 885     if (u->is_CFG()) {
 886       if (u->is_NeverBranch()) {
 887         u = u->as_NeverBranch()->proj_out(0);
 888         enqueue_cfg_uses(u, wq);
 889       } else {
 890         wq.push(u);
 891       }
 892     }
 893   }
 894 }
 895 
 896 // Try moving a store out of a loop, right before the loop
 897 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
 898   // Store has to be first in the loop body
 899   IdealLoopTree *n_loop = get_loop(n_ctrl);
 900   if (n->is_Store() && n_loop != _ltree_root &&
 901       n_loop->is_loop() && n_loop->_head->is_Loop() &&
 902       n->in(0) != nullptr) {
 903     Node* address = n->in(MemNode::Address);
 904     Node* value = n->in(MemNode::ValueIn);
 905     Node* mem = n->in(MemNode::Memory);
 906     IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 907     IdealLoopTree* value_loop = get_loop(get_ctrl(value));
 908 
 909     // - address and value must be loop invariant
 910     // - memory must be a memory Phi for the loop
 911     // - Store must be the only store on this memory slice in the
 912     // loop: if there's another store following this one then value
 913     // written at iteration i by the second store could be overwritten
 914     // at iteration i+n by the first store: it's not safe to move the
 915     // first store out of the loop
 916     // - nothing must observe the memory Phi: it guarantees no read
 917     // before the store, we are also guaranteed the store post
 918     // dominates the loop head (ignoring a possible early
 919     // exit). Otherwise there would be extra Phi involved between the
 920     // loop's Phi and the store.
 921     // - there must be no early exit from the loop before the Store
 922     // (such an exit most of the time would be an extra use of the
 923     // memory Phi but sometimes is a bottom memory Phi that takes the
 924     // store as input).
 925 
 926     if (!n_loop->is_member(address_loop) &&
 927         !n_loop->is_member(value_loop) &&
 928         mem->is_Phi() && mem->in(0) == n_loop->_head &&
 929         mem->outcnt() == 1 &&
 930         mem->in(LoopNode::LoopBackControl) == n) {
 931 
 932       assert(n_loop->_tail != nullptr, "need a tail");
 933       assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
 934 
 935       // Verify that there's no early exit of the loop before the store.
 936       bool ctrl_ok = false;
 937       {
 938         // Follow control from loop head until n, we exit the loop or
 939         // we reach the tail
 940         ResourceMark rm;
 941         Unique_Node_List wq;
 942         wq.push(n_loop->_head);
 943 
 944         for (uint next = 0; next < wq.size(); ++next) {
 945           Node *m = wq.at(next);
 946           if (m == n->in(0)) {
 947             ctrl_ok = true;
 948             continue;
 949           }
 950           assert(!has_ctrl(m), "should be CFG");
 951           if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
 952             ctrl_ok = false;
 953             break;
 954           }
 955           enqueue_cfg_uses(m, wq);
 956           if (wq.size() > 10) {
 957             ctrl_ok = false;
 958             break;
 959           }
 960         }
 961       }
 962       if (ctrl_ok) {
 963         // move the Store
 964         _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
 965         _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
 966         _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
 967         // Disconnect the phi now. An empty phi can confuse other
 968         // optimizations in this pass of loop opts.
 969         _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
 970         n_loop->_body.yank(mem);
 971 
 972         set_ctrl_and_loop(n, n->in(0));
 973 
 974         return n;
 975       }
 976     }
 977   }
 978   return nullptr;
 979 }
 980 
 981 // Try moving a store out of a loop, right after the loop
 982 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
 983   if (n->is_Store() && n->in(0) != nullptr) {
 984     Node *n_ctrl = get_ctrl(n);
 985     IdealLoopTree *n_loop = get_loop(n_ctrl);
 986     // Store must be in a loop
 987     if (n_loop != _ltree_root && !n_loop->_irreducible) {
 988       Node* address = n->in(MemNode::Address);
 989       Node* value = n->in(MemNode::ValueIn);
 990       IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 991       // address must be loop invariant
 992       if (!n_loop->is_member(address_loop)) {
 993         // Store must be last on this memory slice in the loop and
 994         // nothing in the loop must observe it
 995         Node* phi = nullptr;
 996         for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 997           Node* u = n->fast_out(i);
 998           if (has_ctrl(u)) { // control use?
 999             IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1000             if (!n_loop->is_member(u_loop)) {
1001               continue;
1002             }
1003             if (u->is_Phi() && u->in(0) == n_loop->_head) {
1004               assert(_igvn.type(u) == Type::MEMORY, "bad phi");
1005               // multiple phis on the same slice are possible
1006               if (phi != nullptr) {
1007                 return;
1008               }
1009               phi = u;
1010               continue;
1011             }
1012           }
1013           return;
1014         }
1015         if (phi != nullptr) {
1016           // Nothing in the loop before the store (next iteration)
1017           // must observe the stored value
1018           bool mem_ok = true;
1019           {
1020             ResourceMark rm;
1021             Unique_Node_List wq;
1022             wq.push(phi);
1023             for (uint next = 0; next < wq.size() && mem_ok; ++next) {
1024               Node *m = wq.at(next);
1025               for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
1026                 Node* u = m->fast_out(i);
1027                 if (u->is_Store() || u->is_Phi()) {
1028                   if (u != n) {
1029                     wq.push(u);
1030                     mem_ok = (wq.size() <= 10);
1031                   }
1032                 } else {
1033                   mem_ok = false;
1034                   break;
1035                 }
1036               }
1037             }
1038           }
1039           if (mem_ok) {
1040             // Move the store out of the loop if the LCA of all
1041             // users (except for the phi) is outside the loop.
1042             Node* hook = new Node(1);
1043             hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
1044             _igvn.rehash_node_delayed(phi);
1045             int count = phi->replace_edge(n, hook, &_igvn);
1046             assert(count > 0, "inconsistent phi");
1047 
1048             // Compute latest point this store can go
1049             Node* lca = get_late_ctrl(n, get_ctrl(n));
1050             if (lca->is_OuterStripMinedLoop()) {
1051               lca = lca->in(LoopNode::EntryControl);
1052             }
1053             if (n_loop->is_member(get_loop(lca))) {
1054               // LCA is in the loop - bail out
1055               _igvn.replace_node(hook, n);
1056               return;
1057             }
1058 #ifdef ASSERT
1059             if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
1060               assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
1061               n_loop->_head->as_Loop()->verify_strip_mined(1);
1062               Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
1063               IdealLoopTree* outer_loop = get_loop(outer);
1064               assert(n_loop->_parent == outer_loop, "broken loop tree");
1065               assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
1066             }
1067 #endif
1068             lca = place_outside_loop(lca, n_loop);
1069             assert(!n_loop->is_member(get_loop(lca)), "control must not be back in the loop");
1070             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");
1071 
1072             // Move store out of the loop
1073             _igvn.replace_node(hook, n->in(MemNode::Memory));
1074             _igvn.replace_input_of(n, 0, lca);
1075             set_ctrl_and_loop(n, lca);
1076 
1077             // Disconnect the phi now. An empty phi can confuse other
1078             // optimizations in this pass of loop opts..
1079             if (phi->in(LoopNode::LoopBackControl) == phi) {
1080               _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
1081               n_loop->_body.yank(phi);
1082             }
1083           }
1084         }
1085       }
1086     }
1087   }
1088 }
1089 
1090 // Split some nodes that take a counted loop phi as input at a counted
1091 // loop can cause vectorization of some expressions to fail
1092 bool PhaseIdealLoop::split_thru_phi_could_prevent_vectorization(Node* n, Node* n_blk) {
1093   if (!n_blk->is_CountedLoop()) {
1094     return false;
1095   }
1096 
1097   int opcode = n->Opcode();
1098 
1099   if (opcode != Op_AndI &&
1100       opcode != Op_MulI &&
1101       opcode != Op_RotateRight &&
1102       opcode != Op_RShiftI) {
1103     return false;
1104   }
1105 
1106   return n->in(1) == n_blk->as_BaseCountedLoop()->phi();
1107 }
1108 
1109 //------------------------------split_if_with_blocks_pre-----------------------
1110 // Do the real work in a non-recursive function.  Data nodes want to be
1111 // cloned in the pre-order so they can feed each other nicely.
1112 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
1113   // Cloning these guys is unlikely to win
1114   int n_op = n->Opcode();
1115   if (n_op == Op_MergeMem) {
1116     return n;
1117   }
1118   if (n->is_Proj()) {
1119     return n;
1120   }
1121   // Do not clone-up CmpFXXX variations, as these are always
1122   // followed by a CmpI
1123   if (n->is_Cmp()) {
1124     return n;
1125   }
1126   // Attempt to use a conditional move instead of a phi/branch
1127   if (ConditionalMoveLimit > 0 && n_op == Op_Region) {
1128     Node *cmov = conditional_move( n );
1129     if (cmov) {
1130       return cmov;
1131     }
1132   }
1133   if (n->is_CFG() || n->is_LoadStore()) {
1134     return n;
1135   }
1136   if (n->is_Opaque1()) { // Opaque nodes cannot be mod'd
1137     if (!C->major_progress()) {   // If chance of no more loop opts...
1138       _igvn._worklist.push(n);  // maybe we'll remove them
1139     }
1140     return n;
1141   }
1142 
1143   if (n->is_Con()) {
1144     return n;   // No cloning for Con nodes
1145   }
1146 
1147   Node *n_ctrl = get_ctrl(n);
1148   if (!n_ctrl) {
1149     return n;       // Dead node
1150   }
1151 
1152   Node* res = try_move_store_before_loop(n, n_ctrl);
1153   if (res != nullptr) {
1154     return n;
1155   }
1156 
1157   // Attempt to remix address expressions for loop invariants
1158   Node *m = remix_address_expressions( n );
1159   if( m ) return m;
1160 
1161   if (n_op == Op_AddI) {
1162     Node *nn = convert_add_to_muladd( n );
1163     if ( nn ) return nn;
1164   }
1165 
1166   if (n->is_ConstraintCast()) {
1167     Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
1168     // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
1169     // Node control inputs don't necessarily agree with loop control info (due to
1170     // transformations happened in between), thus additional dominance check is needed
1171     // to keep loop info valid.
1172     if (dom_cast != nullptr && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1173       _igvn.replace_node(n, dom_cast);
1174       return dom_cast;
1175     }
1176   }
1177 
1178   // Determine if the Node has inputs from some local Phi.
1179   // Returns the block to clone thru.
1180   Node *n_blk = has_local_phi_input( n );
1181   if( !n_blk ) return n;
1182 
1183   // Do not clone the trip counter through on a CountedLoop
1184   // (messes up the canonical shape).
1185   if (((n_blk->is_CountedLoop() || (n_blk->is_Loop() && n_blk->as_Loop()->is_loop_nest_inner_loop())) && n->Opcode() == Op_AddI) ||
1186       (n_blk->is_LongCountedLoop() && n->Opcode() == Op_AddL)) {
1187     return n;
1188   }
1189   // Pushing a shift through the iv Phi can get in the way of addressing optimizations or range check elimination
1190   if (n_blk->is_BaseCountedLoop() && n->Opcode() == Op_LShift(n_blk->as_BaseCountedLoop()->bt()) &&
1191       n->in(1) == n_blk->as_BaseCountedLoop()->phi()) {
1192     return n;
1193   }
1194 
1195   if (split_thru_phi_could_prevent_vectorization(n, n_blk)) {
1196     return n;
1197   }
1198 
1199   // Check for having no control input; not pinned.  Allow
1200   // dominating control.
1201   if (n->in(0)) {
1202     Node *dom = idom(n_blk);
1203     if (dom_lca(n->in(0), dom) != n->in(0)) {
1204       return n;
1205     }
1206   }
1207   // Policy: when is it profitable.  You must get more wins than
1208   // policy before it is considered profitable.  Policy is usually 0,
1209   // so 1 win is considered profitable.  Big merges will require big
1210   // cloning, so get a larger policy.
1211   int policy = n_blk->req() >> 2;
1212 
1213   // If the loop is a candidate for range check elimination,
1214   // delay splitting through it's phi until a later loop optimization
1215   if (n_blk->is_BaseCountedLoop()) {
1216     IdealLoopTree *lp = get_loop(n_blk);
1217     if (lp && lp->_rce_candidate) {
1218       return n;
1219     }
1220   }
1221 
1222   if (must_throttle_split_if()) return n;
1223 
1224   // Split 'n' through the merge point if it is profitable
1225   Node *phi = split_thru_phi( n, n_blk, policy );
1226   if (!phi) return n;
1227 
1228   // Found a Phi to split thru!
1229   // Replace 'n' with the new phi
1230   _igvn.replace_node( n, phi );
1231   // Moved a load around the loop, 'en-registering' something.
1232   if (n_blk->is_Loop() && n->is_Load() &&
1233       !phi->in(LoopNode::LoopBackControl)->is_Load())
1234     C->set_major_progress();
1235 
1236   return phi;
1237 }
1238 
1239 static bool merge_point_too_heavy(Compile* C, Node* region) {
1240   // Bail out if the region and its phis have too many users.
1241   int weight = 0;
1242   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1243     weight += region->fast_out(i)->outcnt();
1244   }
1245   int nodes_left = C->max_node_limit() - C->live_nodes();
1246   if (weight * 8 > nodes_left) {
1247     if (PrintOpto) {
1248       tty->print_cr("*** Split-if bails out:  %d nodes, region weight %d", C->unique(), weight);
1249     }
1250     return true;
1251   } else {
1252     return false;
1253   }
1254 }
1255 
1256 static bool merge_point_safe(Node* region) {
1257   // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1258   // having a PhiNode input. This sidesteps the dangerous case where the split
1259   // ConvI2LNode may become TOP if the input Value() does not
1260   // overlap the ConvI2L range, leaving a node which may not dominate its
1261   // uses.
1262   // A better fix for this problem can be found in the BugTraq entry, but
1263   // expediency for Mantis demands this hack.
1264 #ifdef _LP64
1265   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1266     Node* n = region->fast_out(i);
1267     if (n->is_Phi()) {
1268       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1269         Node* m = n->fast_out(j);
1270         if (m->Opcode() == Op_ConvI2L)
1271           return false;
1272         if (m->is_CastII()) {
1273           return false;
1274         }
1275       }
1276     }
1277   }
1278 #endif
1279   return true;
1280 }
1281 
1282 
1283 //------------------------------place_outside_loop---------------------------------
1284 // Place some computation outside of this loop on the path to the use passed as argument
1285 Node* PhaseIdealLoop::place_outside_loop(Node* useblock, IdealLoopTree* loop) const {
1286   Node* head = loop->_head;
1287   assert(!loop->is_member(get_loop(useblock)), "must be outside loop");
1288   if (head->is_Loop() && head->as_Loop()->is_strip_mined()) {
1289     loop = loop->_parent;
1290     assert(loop->_head->is_OuterStripMinedLoop(), "malformed strip mined loop");
1291   }
1292 
1293   // Pick control right outside the loop
1294   for (;;) {
1295     Node* dom = idom(useblock);
1296     if (loop->is_member(get_loop(dom))) {
1297       break;
1298     }
1299     useblock = dom;
1300   }
1301   assert(find_non_split_ctrl(useblock) == useblock, "should be non split control");
1302   return useblock;
1303 }
1304 
1305 
1306 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1307   if (!n->is_If() || n->is_BaseCountedLoopEnd()) {
1308     return false;
1309   }
1310   if (!n->in(0)->is_Region()) {
1311     return false;
1312   }
1313 
1314   Node* region = n->in(0);
1315   Node* dom = idom(region);
1316   if (!dom->is_If() ||  !n->as_If()->same_condition(dom, &_igvn)) {
1317     return false;
1318   }
1319   IfNode* dom_if = dom->as_If();
1320   Node* proj_true = dom_if->proj_out(1);
1321   Node* proj_false = dom_if->proj_out(0);
1322 
1323   for (uint i = 1; i < region->req(); i++) {
1324     if (is_dominator(proj_true, region->in(i))) {
1325       continue;
1326     }
1327     if (is_dominator(proj_false, region->in(i))) {
1328       continue;
1329     }
1330     return false;
1331   }
1332 
1333   return true;
1334 }
1335 
1336 
1337 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1338   if (must_throttle_split_if()) {
1339     return false;
1340   }
1341 
1342   // Do not do 'split-if' if irreducible loops are present.
1343   if (_has_irreducible_loops) {
1344     return false;
1345   }
1346 
1347   if (merge_point_too_heavy(C, n_ctrl)) {
1348     return false;
1349   }
1350 
1351   // Do not do 'split-if' if some paths are dead.  First do dead code
1352   // elimination and then see if its still profitable.
1353   for (uint i = 1; i < n_ctrl->req(); i++) {
1354     if (n_ctrl->in(i) == C->top()) {
1355       return false;
1356     }
1357   }
1358 
1359   // If trying to do a 'Split-If' at the loop head, it is only
1360   // profitable if the cmp folds up on BOTH paths.  Otherwise we
1361   // risk peeling a loop forever.
1362 
1363   // CNC - Disabled for now.  Requires careful handling of loop
1364   // body selection for the cloned code.  Also, make sure we check
1365   // for any input path not being in the same loop as n_ctrl.  For
1366   // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1367   // because the alternative loop entry points won't be converted
1368   // into LoopNodes.
1369   IdealLoopTree *n_loop = get_loop(n_ctrl);
1370   for (uint j = 1; j < n_ctrl->req(); j++) {
1371     if (get_loop(n_ctrl->in(j)) != n_loop) {
1372       return false;
1373     }
1374   }
1375 
1376   // Check for safety of the merge point.
1377   if (!merge_point_safe(n_ctrl)) {
1378     return false;
1379   }
1380 
1381   return true;
1382 }
1383 
1384 // Detect if the node is the inner strip-mined loop
1385 // Return: null if it's not the case, or the exit of outer strip-mined loop
1386 static Node* is_inner_of_stripmined_loop(const Node* out) {
1387   Node* out_le = nullptr;
1388 
1389   if (out->is_CountedLoopEnd()) {
1390       const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1391 
1392       if (loop != nullptr && loop->is_strip_mined()) {
1393         out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1394       }
1395   }
1396 
1397   return out_le;
1398 }
1399 
1400 //------------------------------split_if_with_blocks_post----------------------
1401 // Do the real work in a non-recursive function.  CFG hackery wants to be
1402 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1403 // info.
1404 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1405 
1406   // Cloning Cmp through Phi's involves the split-if transform.
1407   // FastLock is not used by an If
1408   if (n->is_Cmp() && !n->is_FastLock()) {
1409     Node *n_ctrl = get_ctrl(n);
1410     // Determine if the Node has inputs from some local Phi.
1411     // Returns the block to clone thru.
1412     Node *n_blk = has_local_phi_input(n);
1413     if (n_blk != n_ctrl) {
1414       return;
1415     }
1416 
1417     if (!can_split_if(n_ctrl)) {
1418       return;
1419     }
1420 
1421     if (n->outcnt() != 1) {
1422       return; // Multiple bool's from 1 compare?
1423     }
1424     Node *bol = n->unique_out();
1425     assert(bol->is_Bool(), "expect a bool here");
1426     if (bol->outcnt() != 1) {
1427       return;// Multiple branches from 1 compare?
1428     }
1429     Node *iff = bol->unique_out();
1430 
1431     // Check some safety conditions
1432     if (iff->is_If()) {        // Classic split-if?
1433       if (iff->in(0) != n_ctrl) {
1434         return; // Compare must be in same blk as if
1435       }
1436     } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1437       // Can't split CMove with different control.
1438       if (get_ctrl(iff) != n_ctrl) {
1439         return;
1440       }
1441       if (get_ctrl(iff->in(2)) == n_ctrl ||
1442           get_ctrl(iff->in(3)) == n_ctrl) {
1443         return;                 // Inputs not yet split-up
1444       }
1445       if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1446         return;                 // Loop-invar test gates loop-varying CMOVE
1447       }
1448     } else {
1449       return;  // some other kind of node, such as an Allocate
1450     }
1451 
1452     // When is split-if profitable?  Every 'win' on means some control flow
1453     // goes dead, so it's almost always a win.
1454     int policy = 0;
1455     // Split compare 'n' through the merge point if it is profitable
1456     Node *phi = split_thru_phi( n, n_ctrl, policy);
1457     if (!phi) {
1458       return;
1459     }
1460 
1461     // Found a Phi to split thru!
1462     // Replace 'n' with the new phi
1463     _igvn.replace_node(n, phi);
1464 
1465     // Now split the bool up thru the phi
1466     Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1467     guarantee(bolphi != nullptr, "null boolean phi node");
1468 
1469     _igvn.replace_node(bol, bolphi);
1470     assert(iff->in(1) == bolphi, "");
1471 
1472     if (bolphi->Value(&_igvn)->singleton()) {
1473       return;
1474     }
1475 
1476     // Conditional-move?  Must split up now
1477     if (!iff->is_If()) {
1478       Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1479       _igvn.replace_node(iff, cmovphi);
1480       return;
1481     }
1482 
1483     // Now split the IF
1484     C->print_method(PHASE_BEFORE_SPLIT_IF, 4, iff);
1485     if ((PrintOpto && VerifyLoopOptimizations) || TraceLoopOpts) {
1486       tty->print_cr("Split-If");
1487     }
1488     do_split_if(iff);
1489     C->print_method(PHASE_AFTER_SPLIT_IF, 4, iff);
1490     return;
1491   }
1492 
1493   // Two identical ifs back to back can be merged
1494   if (try_merge_identical_ifs(n)) {
1495     return;
1496   }
1497 
1498   // Check for an IF ready to split; one that has its
1499   // condition codes input coming from a Phi at the block start.
1500   int n_op = n->Opcode();
1501 
1502   // Check for an IF being dominated by another IF same test
1503   if (n_op == Op_If ||
1504       n_op == Op_RangeCheck) {
1505     Node *bol = n->in(1);
1506     uint max = bol->outcnt();
1507     // Check for same test used more than once?
1508     if (bol->is_Bool() && (max > 1 || bol->in(1)->is_SubTypeCheck())) {
1509       // Search up IDOMs to see if this IF is dominated.
1510       Node* cmp = bol->in(1);
1511       Node *cutoff = cmp->is_SubTypeCheck() ? dom_lca(get_ctrl(cmp->in(1)), get_ctrl(cmp->in(2))) : get_ctrl(bol);
1512 
1513       // Now search up IDOMs till cutoff, looking for a dominating test
1514       Node *prevdom = n;
1515       Node *dom = idom(prevdom);
1516       while (dom != cutoff) {
1517         if (dom->req() > 1 && n->as_If()->same_condition(dom, &_igvn) && prevdom->in(0) == dom &&
1518             safe_for_if_replacement(dom)) {
1519           // It's invalid to move control dependent data nodes in the inner
1520           // strip-mined loop, because:
1521           //  1) break validation of LoopNode::verify_strip_mined()
1522           //  2) move code with side-effect in strip-mined loop
1523           // Move to the exit of outer strip-mined loop in that case.
1524           Node* out_le = is_inner_of_stripmined_loop(dom);
1525           if (out_le != nullptr) {
1526             prevdom = out_le;
1527           }
1528           // Replace the dominated test with an obvious true or false.
1529           // Place it on the IGVN worklist for later cleanup.
1530           C->set_major_progress();
1531           // Split if: pin array accesses that are control dependent on a range check and moved to a regular if,
1532           // to prevent an array load from floating above its range check. There are three cases:
1533           // 1. Move from RangeCheck "a" to RangeCheck "b": don't need to pin. If we ever remove b, then we pin
1534           //    all its array accesses at that point.
1535           // 2. We move from RangeCheck "a" to regular if "b": need to pin. If we ever remove b, then its array
1536           //    accesses would start to float, since we don't pin at that point.
1537           // 3. If we move from regular if: don't pin. All array accesses are already assumed to be pinned.
1538           bool pin_array_access_nodes =  n->Opcode() == Op_RangeCheck &&
1539                                          prevdom->in(0)->Opcode() != Op_RangeCheck;
1540           dominated_by(prevdom->as_IfProj(), n->as_If(), false, pin_array_access_nodes);
1541           DEBUG_ONLY( if (VerifyLoopOptimizations) { verify(); } );
1542           return;
1543         }
1544         prevdom = dom;
1545         dom = idom(prevdom);
1546       }
1547     }
1548   }
1549 
1550   try_sink_out_of_loop(n);
1551   if (C->failing()) {
1552     return;
1553   }
1554 
1555   try_move_store_after_loop(n);
1556 }
1557 
1558 // Transform:
1559 //
1560 // if (some_condition) {
1561 //   // body 1
1562 // } else {
1563 //   // body 2
1564 // }
1565 // if (some_condition) {
1566 //   // body 3
1567 // } else {
1568 //   // body 4
1569 // }
1570 //
1571 // into:
1572 //
1573 //
1574 // if (some_condition) {
1575 //   // body 1
1576 //   // body 3
1577 // } else {
1578 //   // body 2
1579 //   // body 4
1580 // }
1581 bool PhaseIdealLoop::try_merge_identical_ifs(Node* n) {
1582   if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1583     Node *n_ctrl = n->in(0);
1584     IfNode* dom_if = idom(n_ctrl)->as_If();
1585     if (n->in(1) != dom_if->in(1)) {
1586       assert(n->in(1)->in(1)->is_SubTypeCheck() &&
1587              (n->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr ||
1588               dom_if->in(1)->in(1)->as_SubTypeCheck()->method() != nullptr), "only for subtype checks with profile data attached");
1589       _igvn.replace_input_of(n, 1, dom_if->in(1));
1590     }
1591     ProjNode* dom_proj_true = dom_if->proj_out(1);
1592     ProjNode* dom_proj_false = dom_if->proj_out(0);
1593 
1594     // Now split the IF
1595     RegionNode* new_false_region;
1596     RegionNode* new_true_region;
1597     do_split_if(n, &new_false_region, &new_true_region);
1598     assert(new_false_region->req() == new_true_region->req(), "");
1599 #ifdef ASSERT
1600     for (uint i = 1; i < new_false_region->req(); ++i) {
1601       assert(new_false_region->in(i)->in(0) == new_true_region->in(i)->in(0), "unexpected shape following split if");
1602       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");
1603     }
1604 #endif
1605     assert(new_false_region->in(1)->in(0)->in(1) == dom_if->in(1), "dominating if and dominated if after split must share test");
1606 
1607     // We now have:
1608     // if (some_condition) {
1609     //   // body 1
1610     //   if (some_condition) {
1611     //     body3: // new_true_region
1612     //     // body3
1613     //   } else {
1614     //     goto body4;
1615     //   }
1616     // } else {
1617     //   // body 2
1618     //  if (some_condition) {
1619     //     goto body3;
1620     //   } else {
1621     //     body4:   // new_false_region
1622     //     // body4;
1623     //   }
1624     // }
1625     //
1626 
1627     // clone pinned nodes thru the resulting regions
1628     push_pinned_nodes_thru_region(dom_if, new_true_region);
1629     push_pinned_nodes_thru_region(dom_if, new_false_region);
1630 
1631     // Optimize out the cloned ifs. Because pinned nodes were cloned, this also allows a CastPP that would be dependent
1632     // 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
1633     // unrelated control dependency.
1634     for (uint i = 1; i < new_false_region->req(); i++) {
1635       if (is_dominator(dom_proj_true, new_false_region->in(i))) {
1636         dominated_by(dom_proj_true->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1637       } else {
1638         assert(is_dominator(dom_proj_false, new_false_region->in(i)), "bad if");
1639         dominated_by(dom_proj_false->as_IfProj(), new_false_region->in(i)->in(0)->as_If());
1640       }
1641     }
1642     return true;
1643   }
1644   return false;
1645 }
1646 
1647 void PhaseIdealLoop::push_pinned_nodes_thru_region(IfNode* dom_if, Node* region) {
1648   for (DUIterator i = region->outs(); region->has_out(i); i++) {
1649     Node* u = region->out(i);
1650     if (!has_ctrl(u) || u->is_Phi() || !u->depends_only_on_test() || !_igvn.no_dependent_zero_check(u)) {
1651       continue;
1652     }
1653     assert(u->in(0) == region, "not a control dependent node?");
1654     uint j = 1;
1655     for (; j < u->req(); ++j) {
1656       Node* in = u->in(j);
1657       if (!is_dominator(ctrl_or_self(in), dom_if)) {
1658         break;
1659       }
1660     }
1661     if (j == u->req()) {
1662       Node *phi = PhiNode::make_blank(region, u);
1663       for (uint k = 1; k < region->req(); ++k) {
1664         Node* clone = u->clone();
1665         clone->set_req(0, region->in(k));
1666         register_new_node(clone, region->in(k));
1667         phi->init_req(k, clone);
1668       }
1669       register_new_node(phi, region);
1670       _igvn.replace_node(u, phi);
1671       --i;
1672     }
1673   }
1674 }
1675 
1676 bool PhaseIdealLoop::safe_for_if_replacement(const Node* dom) const {
1677   if (!dom->is_CountedLoopEnd()) {
1678     return true;
1679   }
1680   CountedLoopEndNode* le = dom->as_CountedLoopEnd();
1681   CountedLoopNode* cl = le->loopnode();
1682   if (cl == nullptr) {
1683     return true;
1684   }
1685   if (!cl->is_main_loop()) {
1686     return true;
1687   }
1688   if (cl->is_canonical_loop_entry() == nullptr) {
1689     return true;
1690   }
1691   // Further unrolling is possible so loop exit condition might change
1692   return false;
1693 }
1694 
1695 // See if a shared loop-varying computation has no loop-varying uses.
1696 // Happens if something is only used for JVM state in uncommon trap exits,
1697 // like various versions of induction variable+offset.  Clone the
1698 // computation per usage to allow it to sink out of the loop.
1699 void PhaseIdealLoop::try_sink_out_of_loop(Node* n) {
1700   if (has_ctrl(n) &&
1701       !n->is_Phi() &&
1702       !n->is_Bool() &&
1703       !n->is_Proj() &&
1704       !n->is_MergeMem() &&
1705       !n->is_CMove() &&
1706       !n->is_OpaqueNotNull() &&
1707       !n->is_OpaqueInitializedAssertionPredicate() &&
1708       !n->is_OpaqueTemplateAssertionPredicate() &&
1709       !n->is_Type()) {
1710     Node *n_ctrl = get_ctrl(n);
1711     IdealLoopTree *n_loop = get_loop(n_ctrl);
1712 
1713     if (n->in(0) != nullptr) {
1714       IdealLoopTree* loop_ctrl = get_loop(n->in(0));
1715       if (n_loop != loop_ctrl && n_loop->is_member(loop_ctrl)) {
1716         // n has a control input inside a loop but get_ctrl() is member of an outer loop. This could happen, for example,
1717         // for Div nodes inside a loop (control input inside loop) without a use except for an UCT (outside the loop).
1718         // Rewire control of n to right outside of the loop, regardless if its input(s) are later sunk or not.
1719         Node* maybe_pinned_n = n;
1720         Node* outside_ctrl = place_outside_loop(n_ctrl, loop_ctrl);
1721         if (n->depends_only_on_test()) {
1722           Node* pinned_clone = n->pin_array_access_node();
1723           if (pinned_clone != nullptr) {
1724             // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1725             // range check for that access. If that condition is replaced by an identical dominating one, then an
1726             // unpinned load would risk floating above its range check.
1727             register_new_node(pinned_clone, n_ctrl);
1728             maybe_pinned_n = pinned_clone;
1729             _igvn.replace_node(n, pinned_clone);
1730           }
1731         }
1732         _igvn.replace_input_of(maybe_pinned_n, 0, outside_ctrl);
1733       }
1734     }
1735     if (n_loop != _ltree_root && n->outcnt() > 1) {
1736       // Compute early control: needed for anti-dependence analysis. It's also possible that as a result of
1737       // previous transformations in this loop opts round, the node can be hoisted now: early control will tell us.
1738       Node* early_ctrl = compute_early_ctrl(n, n_ctrl);
1739       if (n_loop->is_member(get_loop(early_ctrl)) && // check that this one can't be hoisted now
1740           ctrl_of_all_uses_out_of_loop(n, early_ctrl, n_loop)) { // All uses in outer loops!
1741         if (n->is_Store() || n->is_LoadStore()) {
1742             assert(false, "no node with a side effect");
1743             C->record_failure("no node with a side effect");
1744             return;
1745         }
1746         Node* outer_loop_clone = nullptr;
1747         for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin;) {
1748           Node* u = n->last_out(j); // Clone private computation per use
1749           _igvn.rehash_node_delayed(u);
1750           Node* x = nullptr;
1751           if (n->depends_only_on_test()) {
1752             // Pin array access nodes: if this is an array load, it's going to be dependent on a condition that's not a
1753             // range check for that access. If that condition is replaced by an identical dominating one, then an
1754             // unpinned load would risk floating above its range check.
1755             x = n->pin_array_access_node();
1756           }
1757           if (x == nullptr) {
1758             x = n->clone();
1759           }
1760           Node* x_ctrl = nullptr;
1761           if (u->is_Phi()) {
1762             // Replace all uses of normal nodes.  Replace Phi uses
1763             // individually, so the separate Nodes can sink down
1764             // different paths.
1765             uint k = 1;
1766             while (u->in(k) != n) k++;
1767             u->set_req(k, x);
1768             // x goes next to Phi input path
1769             x_ctrl = u->in(0)->in(k);
1770             // Find control for 'x' next to use but not inside inner loops.
1771             x_ctrl = place_outside_loop(x_ctrl, n_loop);
1772             --j;
1773           } else {              // Normal use
1774             if (has_ctrl(u)) {
1775               x_ctrl = get_ctrl(u);
1776             } else {
1777               x_ctrl = u->in(0);
1778             }
1779             // Find control for 'x' next to use but not inside inner loops.
1780             x_ctrl = place_outside_loop(x_ctrl, n_loop);
1781             // Replace all uses
1782             if (u->is_ConstraintCast() && _igvn.type(n)->higher_equal(u->bottom_type()) && u->in(0) == x_ctrl) {
1783               // If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary
1784               // anymore now that we're going to pin n as well
1785               _igvn.replace_node(u, x);
1786               --j;
1787             } else {
1788               int nb = u->replace_edge(n, x, &_igvn);
1789               j -= nb;
1790             }
1791           }
1792 
1793           if (n->is_Load()) {
1794             // For loads, add a control edge to a CFG node outside of the loop
1795             // to force them to not combine and return back inside the loop
1796             // during GVN optimization (4641526).
1797             assert(x_ctrl == get_late_ctrl_with_anti_dep(x->as_Load(), early_ctrl, x_ctrl), "anti-dependences were already checked");
1798 
1799             IdealLoopTree* x_loop = get_loop(x_ctrl);
1800             Node* x_head = x_loop->_head;
1801             if (x_head->is_Loop() && x_head->is_OuterStripMinedLoop()) {
1802               // Do not add duplicate LoadNodes to the outer strip mined loop
1803               if (outer_loop_clone != nullptr) {
1804                 _igvn.replace_node(x, outer_loop_clone);
1805                 continue;
1806               }
1807               outer_loop_clone = x;
1808             }
1809             x->set_req(0, x_ctrl);
1810           } else if (n->in(0) != nullptr){
1811             x->set_req(0, x_ctrl);
1812           }
1813           assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1814           assert(!n_loop->is_member(get_loop(x_ctrl)), "should have moved out of loop");
1815           register_new_node(x, x_ctrl);
1816 
1817           // Chain of AddP nodes: (AddP base (AddP base (AddP base )))
1818           // All AddP nodes must keep the same base after sinking so:
1819           // 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,
1820           // their bases remain the same.
1821           // (see 2- below)
1822           assert(!x->is_AddP() || !x->in(AddPNode::Address)->is_AddP() ||
1823                  x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base) ||
1824                  !x->in(AddPNode::Address)->in(AddPNode::Base)->eqv_uncast(x->in(AddPNode::Base)), "unexpected AddP shape");
1825           if (x->in(0) == nullptr && !x->is_DecodeNarrowPtr() &&
1826               !(x->is_AddP() && x->in(AddPNode::Address)->is_AddP() && x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base))) {
1827             assert(!x->is_Load(), "load should be pinned");
1828             // Use a cast node to pin clone out of loop
1829             Node* cast = nullptr;
1830             for (uint k = 0; k < x->req(); k++) {
1831               Node* in = x->in(k);
1832               if (in != nullptr && n_loop->is_member(get_loop(get_ctrl(in)))) {
1833                 const Type* in_t = _igvn.type(in);
1834                 cast = ConstraintCastNode::make_cast_for_type(x_ctrl, in, in_t,
1835                                                               ConstraintCastNode::UnconditionalDependency, nullptr);
1836               }
1837               if (cast != nullptr) {
1838                 Node* prev = _igvn.hash_find_insert(cast);
1839                 if (prev != nullptr && get_ctrl(prev) == x_ctrl) {
1840                   cast->destruct(&_igvn);
1841                   cast = prev;
1842                 } else {
1843                   register_new_node(cast, x_ctrl);
1844                 }
1845                 x->replace_edge(in, cast);
1846                 // Chain of AddP nodes:
1847                 // 2- A CastPP of the base is only added now that all AddP nodes are sunk
1848                 if (x->is_AddP() && k == AddPNode::Base) {
1849                   update_addp_chain_base(x, n->in(AddPNode::Base), cast);
1850                 }
1851                 break;
1852               }
1853             }
1854             assert(cast != nullptr, "must have added a cast to pin the node");
1855           }
1856         }
1857         _igvn.remove_dead_node(n);
1858       }
1859       _dom_lca_tags_round = 0;
1860     }
1861   }
1862 }
1863 
1864 void PhaseIdealLoop::update_addp_chain_base(Node* x, Node* old_base, Node* new_base) {
1865   ResourceMark rm;
1866   Node_List wq;
1867   wq.push(x);
1868   while (wq.size() != 0) {
1869     Node* n = wq.pop();
1870     for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1871       Node* u = n->fast_out(i);
1872       if (u->is_AddP() && u->in(AddPNode::Base) == old_base) {
1873         _igvn.replace_input_of(u, AddPNode::Base, new_base);
1874         wq.push(u);
1875       }
1876     }
1877   }
1878 }
1879 
1880 // Compute the early control of a node by following its inputs until we reach
1881 // nodes that are pinned. Then compute the LCA of the control of all pinned nodes.
1882 Node* PhaseIdealLoop::compute_early_ctrl(Node* n, Node* n_ctrl) {
1883   Node* early_ctrl = nullptr;
1884   ResourceMark rm;
1885   Unique_Node_List wq;
1886   wq.push(n);
1887   for (uint i = 0; i < wq.size(); i++) {
1888     Node* m = wq.at(i);
1889     Node* c = nullptr;
1890     if (m->is_CFG()) {
1891       c = m;
1892     } else if (m->pinned()) {
1893       c = m->in(0);
1894     } else {
1895       for (uint j = 0; j < m->req(); j++) {
1896         Node* in = m->in(j);
1897         if (in != nullptr) {
1898           wq.push(in);
1899         }
1900       }
1901     }
1902     if (c != nullptr) {
1903       assert(is_dominator(c, n_ctrl), "control input must dominate current control");
1904       if (early_ctrl == nullptr || is_dominator(early_ctrl, c)) {
1905         early_ctrl = c;
1906       }
1907     }
1908   }
1909   assert(is_dominator(early_ctrl, n_ctrl), "early control must dominate current control");
1910   return early_ctrl;
1911 }
1912 
1913 bool PhaseIdealLoop::ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop) {
1914   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1915     Node* u = n->fast_out(i);
1916     if (u->is_Opaque1()) {
1917       return false;  // Found loop limit, bugfix for 4677003
1918     }
1919     // We can't reuse tags in PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal() so make sure calls to
1920     // get_late_ctrl_with_anti_dep() use their own tag
1921     _dom_lca_tags_round++;
1922     assert(_dom_lca_tags_round != 0, "shouldn't wrap around");
1923 
1924     if (u->is_Phi()) {
1925       for (uint j = 1; j < u->req(); ++j) {
1926         if (u->in(j) == n && !ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, u->in(0)->in(j))) {
1927           return false;
1928         }
1929       }
1930     } else {
1931       Node* ctrl = has_ctrl(u) ? get_ctrl(u) : u->in(0);
1932       if (!ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, ctrl)) {
1933         return false;
1934       }
1935     }
1936   }
1937   return true;
1938 }
1939 
1940 bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl) {
1941   if (n->is_Load()) {
1942     ctrl = get_late_ctrl_with_anti_dep(n->as_Load(), n_ctrl, ctrl);
1943   }
1944   IdealLoopTree *u_loop = get_loop(ctrl);
1945   if (u_loop == n_loop) {
1946     return false; // Found loop-varying use
1947   }
1948   if (n_loop->is_member(u_loop)) {
1949     return false; // Found use in inner loop
1950   }
1951   // 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
1952   // to a check that's eliminated by range check elimination, it becomes input to an expression that feeds into the exit
1953   // test of the pre loop above the point in the graph where it's pinned.
1954   if (n_loop->_head->is_CountedLoop() && n_loop->_head->as_CountedLoop()->is_pre_loop()) {
1955     CountedLoopNode* pre_loop = n_loop->_head->as_CountedLoop();
1956     if (is_dominator(pre_loop->loopexit(), ctrl)) {
1957       return false;
1958     }
1959   }
1960   return true;
1961 }
1962 
1963 //------------------------------split_if_with_blocks---------------------------
1964 // Check for aggressive application of 'split-if' optimization,
1965 // using basic block level info.
1966 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1967   Node* root = C->root();
1968   visited.set(root->_idx); // first, mark root as visited
1969   // Do pre-visit work for root
1970   Node* n   = split_if_with_blocks_pre(root);
1971   uint  cnt = n->outcnt();
1972   uint  i   = 0;
1973 
1974   while (true) {
1975     // Visit all children
1976     if (i < cnt) {
1977       Node* use = n->raw_out(i);
1978       ++i;
1979       if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1980         // Now do pre-visit work for this use
1981         use = split_if_with_blocks_pre(use);
1982         nstack.push(n, i); // Save parent and next use's index.
1983         n   = use;         // Process all children of current use.
1984         cnt = use->outcnt();
1985         i   = 0;
1986       }
1987     }
1988     else {
1989       // All of n's children have been processed, complete post-processing.
1990       if (cnt != 0 && !n->is_Con()) {
1991         assert(has_node(n), "no dead nodes");
1992         split_if_with_blocks_post(n);
1993         if (C->failing()) {
1994           return;
1995         }
1996       }
1997       if (must_throttle_split_if()) {
1998         nstack.clear();
1999       }
2000       if (nstack.is_empty()) {
2001         // Finished all nodes on stack.
2002         break;
2003       }
2004       // Get saved parent node and next use's index. Visit the rest of uses.
2005       n   = nstack.node();
2006       cnt = n->outcnt();
2007       i   = nstack.index();
2008       nstack.pop();
2009     }
2010   }
2011 }
2012 
2013 
2014 //=============================================================================
2015 //
2016 //                   C L O N E   A   L O O P   B O D Y
2017 //
2018 
2019 //------------------------------clone_iff--------------------------------------
2020 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2021 // "Nearly" because all Nodes have been cloned from the original in the loop,
2022 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
2023 // through the Phi recursively, and return a Bool.
2024 Node* PhaseIdealLoop::clone_iff(PhiNode* phi) {
2025 
2026   // Convert this Phi into a Phi merging Bools
2027   uint i;
2028   for (i = 1; i < phi->req(); i++) {
2029     Node* b = phi->in(i);
2030     if (b->is_Phi()) {
2031       _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi()));
2032     } else {
2033       assert(b->is_Bool() || b->is_OpaqueNotNull() || b->is_OpaqueInitializedAssertionPredicate(),
2034              "bool, non-null check with OpaqueNotNull or Initialized Assertion Predicate with its Opaque node");
2035     }
2036   }
2037   Node* n = phi->in(1);
2038   Node* sample_opaque = nullptr;
2039   Node *sample_bool = nullptr;
2040   if (n->is_OpaqueNotNull() || n->is_OpaqueInitializedAssertionPredicate()) {
2041     sample_opaque = n;
2042     sample_bool = n->in(1);
2043     assert(sample_bool->is_Bool(), "wrong type");
2044   } else {
2045     sample_bool = n;
2046   }
2047   Node *sample_cmp = sample_bool->in(1);
2048 
2049   // Make Phis to merge the Cmp's inputs.
2050   PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
2051   PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
2052   for (i = 1; i < phi->req(); i++) {
2053     Node *n1 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
2054     Node *n2 = sample_opaque == nullptr ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
2055     phi1->set_req(i, n1);
2056     phi2->set_req(i, n2);
2057     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2058     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2059   }
2060   // See if these Phis have been made before.
2061   // Register with optimizer
2062   Node *hit1 = _igvn.hash_find_insert(phi1);
2063   if (hit1) {                   // Hit, toss just made Phi
2064     _igvn.remove_dead_node(phi1); // Remove new phi
2065     assert(hit1->is_Phi(), "" );
2066     phi1 = (PhiNode*)hit1;      // Use existing phi
2067   } else {                      // Miss
2068     _igvn.register_new_node_with_optimizer(phi1);
2069   }
2070   Node *hit2 = _igvn.hash_find_insert(phi2);
2071   if (hit2) {                   // Hit, toss just made Phi
2072     _igvn.remove_dead_node(phi2); // Remove new phi
2073     assert(hit2->is_Phi(), "" );
2074     phi2 = (PhiNode*)hit2;      // Use existing phi
2075   } else {                      // Miss
2076     _igvn.register_new_node_with_optimizer(phi2);
2077   }
2078   // Register Phis with loop/block info
2079   set_ctrl(phi1, phi->in(0));
2080   set_ctrl(phi2, phi->in(0));
2081   // Make a new Cmp
2082   Node *cmp = sample_cmp->clone();
2083   cmp->set_req(1, phi1);
2084   cmp->set_req(2, phi2);
2085   _igvn.register_new_node_with_optimizer(cmp);
2086   set_ctrl(cmp, phi->in(0));
2087 
2088   // Make a new Bool
2089   Node *b = sample_bool->clone();
2090   b->set_req(1,cmp);
2091   _igvn.register_new_node_with_optimizer(b);
2092   set_ctrl(b, phi->in(0));
2093 
2094   if (sample_opaque != nullptr) {
2095     Node* opaque = sample_opaque->clone();
2096     opaque->set_req(1, b);
2097     _igvn.register_new_node_with_optimizer(opaque);
2098     set_ctrl(opaque, phi->in(0));
2099     return opaque;
2100   }
2101 
2102   assert(b->is_Bool(), "");
2103   return b;
2104 }
2105 
2106 //------------------------------clone_bool-------------------------------------
2107 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2108 // "Nearly" because all Nodes have been cloned from the original in the loop,
2109 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
2110 // through the Phi recursively, and return a Bool.
2111 CmpNode*PhaseIdealLoop::clone_bool(PhiNode* phi) {
2112   uint i;
2113   // Convert this Phi into a Phi merging Bools
2114   for( i = 1; i < phi->req(); i++ ) {
2115     Node *b = phi->in(i);
2116     if( b->is_Phi() ) {
2117       _igvn.replace_input_of(phi, i, clone_bool(b->as_Phi()));
2118     } else {
2119       assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
2120     }
2121   }
2122 
2123   Node *sample_cmp = phi->in(1);
2124 
2125   // Make Phis to merge the Cmp's inputs.
2126   PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
2127   PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
2128   for( uint j = 1; j < phi->req(); j++ ) {
2129     Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
2130     Node *n1, *n2;
2131     if( cmp_top->is_Cmp() ) {
2132       n1 = cmp_top->in(1);
2133       n2 = cmp_top->in(2);
2134     } else {
2135       n1 = n2 = cmp_top;
2136     }
2137     phi1->set_req( j, n1 );
2138     phi2->set_req( j, n2 );
2139     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2140     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2141   }
2142 
2143   // See if these Phis have been made before.
2144   // Register with optimizer
2145   Node *hit1 = _igvn.hash_find_insert(phi1);
2146   if( hit1 ) {                  // Hit, toss just made Phi
2147     _igvn.remove_dead_node(phi1); // Remove new phi
2148     assert( hit1->is_Phi(), "" );
2149     phi1 = (PhiNode*)hit1;      // Use existing phi
2150   } else {                      // Miss
2151     _igvn.register_new_node_with_optimizer(phi1);
2152   }
2153   Node *hit2 = _igvn.hash_find_insert(phi2);
2154   if( hit2 ) {                  // Hit, toss just made Phi
2155     _igvn.remove_dead_node(phi2); // Remove new phi
2156     assert( hit2->is_Phi(), "" );
2157     phi2 = (PhiNode*)hit2;      // Use existing phi
2158   } else {                      // Miss
2159     _igvn.register_new_node_with_optimizer(phi2);
2160   }
2161   // Register Phis with loop/block info
2162   set_ctrl(phi1, phi->in(0));
2163   set_ctrl(phi2, phi->in(0));
2164   // Make a new Cmp
2165   Node *cmp = sample_cmp->clone();
2166   cmp->set_req( 1, phi1 );
2167   cmp->set_req( 2, phi2 );
2168   _igvn.register_new_node_with_optimizer(cmp);
2169   set_ctrl(cmp, phi->in(0));
2170 
2171   assert( cmp->is_Cmp(), "" );
2172   return (CmpNode*)cmp;
2173 }
2174 
2175 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
2176                                                  IdealLoopTree* loop, IdealLoopTree* outer_loop,
2177                                                  Node_List*& split_if_set, Node_List*& split_bool_set,
2178                                                  Node_List*& split_cex_set, Node_List& worklist,
2179                                                  uint new_counter, CloneLoopMode mode) {
2180   Node* nnn = old_new[old->_idx];
2181   // Copy uses to a worklist, so I can munge the def-use info
2182   // with impunity.
2183   for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2184     worklist.push(old->fast_out(j));
2185 
2186   while( worklist.size() ) {
2187     Node *use = worklist.pop();
2188     if (!has_node(use))  continue; // Ignore dead nodes
2189     if (use->in(0) == C->top())  continue;
2190     IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2191     // Check for data-use outside of loop - at least one of OLD or USE
2192     // must not be a CFG node.
2193 #ifdef ASSERT
2194     if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == nullptr) {
2195       Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
2196       assert(mode != IgnoreStripMined, "incorrect cloning mode");
2197       assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
2198     }
2199 #endif
2200     if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
2201 
2202       // If the Data use is an IF, that means we have an IF outside the
2203       // loop that is switching on a condition that is set inside the
2204       // loop.  Happens if people set a loop-exit flag; then test the flag
2205       // in the loop to break the loop, then test is again outside the
2206       // loop to determine which way the loop exited.
2207       //
2208       // For several uses we need to make sure that there is no phi between,
2209       // the use and the Bool/Cmp. We therefore clone the Bool/Cmp down here
2210       // to avoid such a phi in between.
2211       // For example, it is unexpected that there is a Phi between an
2212       // AllocateArray node and its ValidLengthTest input that could cause
2213       // split if to break.
2214       assert(!use->is_OpaqueTemplateAssertionPredicate(),
2215              "should not clone a Template Assertion Predicate which should be removed once it's useless");
2216       if (use->is_If() || use->is_CMove() || use->is_OpaqueNotNull() || use->is_OpaqueInitializedAssertionPredicate() ||
2217           (use->Opcode() == Op_AllocateArray && use->in(AllocateNode::ValidLengthTest) == old)) {
2218         // Since this code is highly unlikely, we lazily build the worklist
2219         // of such Nodes to go split.
2220         if (!split_if_set) {
2221           split_if_set = new Node_List();
2222         }
2223         split_if_set->push(use);
2224       }
2225       if (use->is_Bool()) {
2226         if (!split_bool_set) {
2227           split_bool_set = new Node_List();
2228         }
2229         split_bool_set->push(use);
2230       }
2231       if (use->Opcode() == Op_CreateEx) {
2232         if (!split_cex_set) {
2233           split_cex_set = new Node_List();
2234         }
2235         split_cex_set->push(use);
2236       }
2237 
2238 
2239       // Get "block" use is in
2240       uint idx = 0;
2241       while( use->in(idx) != old ) idx++;
2242       Node *prev = use->is_CFG() ? use : get_ctrl(use);
2243       assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
2244       Node* cfg = (prev->_idx >= new_counter && prev->is_Region())
2245         ? prev->in(2)
2246         : idom(prev);
2247       if( use->is_Phi() )     // Phi use is in prior block
2248         cfg = prev->in(idx);  // NOT in block of Phi itself
2249       if (cfg->is_top()) {    // Use is dead?
2250         _igvn.replace_input_of(use, idx, C->top());
2251         continue;
2252       }
2253 
2254       // If use is referenced through control edge... (idx == 0)
2255       if (mode == IgnoreStripMined && idx == 0) {
2256         LoopNode *head = loop->_head->as_Loop();
2257         if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
2258           // That node is outside the inner loop, leave it outside the
2259           // outer loop as well to not confuse verification code.
2260           assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
2261           _igvn.replace_input_of(use, 0, head->outer_loop_exit());
2262           continue;
2263         }
2264       }
2265 
2266       while(!outer_loop->is_member(get_loop(cfg))) {
2267         prev = cfg;
2268         cfg = (cfg->_idx >= new_counter && cfg->is_Region()) ? cfg->in(2) : idom(cfg);
2269       }
2270       // If the use occurs after merging several exits from the loop, then
2271       // old value must have dominated all those exits.  Since the same old
2272       // value was used on all those exits we did not need a Phi at this
2273       // merge point.  NOW we do need a Phi here.  Each loop exit value
2274       // is now merged with the peeled body exit; each exit gets its own
2275       // private Phi and those Phis need to be merged here.
2276       Node *phi;
2277       if( prev->is_Region() ) {
2278         if( idx == 0 ) {      // Updating control edge?
2279           phi = prev;         // Just use existing control
2280         } else {              // Else need a new Phi
2281           phi = PhiNode::make( prev, old );
2282           // Now recursively fix up the new uses of old!
2283           for( uint i = 1; i < prev->req(); i++ ) {
2284             worklist.push(phi); // Onto worklist once for each 'old' input
2285           }
2286         }
2287       } else {
2288         // Get new RegionNode merging old and new loop exits
2289         prev = old_new[prev->_idx];
2290         assert( prev, "just made this in step 7" );
2291         if( idx == 0) {      // Updating control edge?
2292           phi = prev;         // Just use existing control
2293         } else {              // Else need a new Phi
2294           // Make a new Phi merging data values properly
2295           phi = PhiNode::make( prev, old );
2296           phi->set_req( 1, nnn );
2297         }
2298       }
2299       // If inserting a new Phi, check for prior hits
2300       if( idx != 0 ) {
2301         Node *hit = _igvn.hash_find_insert(phi);
2302         if( hit == nullptr ) {
2303           _igvn.register_new_node_with_optimizer(phi); // Register new phi
2304         } else {                                      // or
2305           // Remove the new phi from the graph and use the hit
2306           _igvn.remove_dead_node(phi);
2307           phi = hit;                                  // Use existing phi
2308         }
2309         set_ctrl(phi, prev);
2310       }
2311       // Make 'use' use the Phi instead of the old loop body exit value
2312       assert(use->in(idx) == old, "old is still input of use");
2313       // We notify all uses of old, including use, and the indirect uses,
2314       // that may now be optimized because we have replaced old with phi.
2315       _igvn.add_users_to_worklist(old);
2316       if (idx == 0 &&
2317           use->depends_only_on_test()) {
2318         Node* pinned_clone = use->pin_array_access_node();
2319         if (pinned_clone != nullptr) {
2320           // Pin array access nodes: control is updated here to a region. If, after some transformations, only one path
2321           // into the region is left, an array load could become dependent on a condition that's not a range check for
2322           // that access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
2323           // floating above its range check.
2324           pinned_clone->set_req(0, phi);
2325           register_new_node_with_ctrl_of(pinned_clone, use);
2326           _igvn.replace_node(use, pinned_clone);
2327           continue;
2328         }
2329       }
2330       _igvn.replace_input_of(use, idx, phi);
2331       if( use->_idx >= new_counter ) { // If updating new phis
2332         // Not needed for correctness, but prevents a weak assert
2333         // in AddPNode from tripping (when we end up with different
2334         // base & derived Phis that will become the same after
2335         // IGVN does CSE).
2336         Node *hit = _igvn.hash_find_insert(use);
2337         if( hit )             // Go ahead and re-hash for hits.
2338           _igvn.replace_node( use, hit );
2339       }
2340     }
2341   }
2342 }
2343 
2344 static void collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
2345                                                                 const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
2346                                                                 bool check_old_new) {
2347   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2348     Node* u = n->fast_out(j);
2349     assert(check_old_new || old_new[u->_idx] == nullptr, "shouldn't have been cloned");
2350     if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == nullptr)) {
2351       Node* c = phase->get_ctrl(u);
2352       IdealLoopTree* u_loop = phase->get_loop(c);
2353       assert(!loop->is_member(u_loop) || !loop->_body.contains(u), "can be in outer loop or out of both loops only");
2354       if (!loop->is_member(u_loop)) {
2355         if (outer_loop->is_member(u_loop)) {
2356           wq.push(u);
2357         } else {
2358           // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
2359           // the outer loop too
2360           Node* u_c = u->in(0);
2361           if (u_c != nullptr) {
2362             IdealLoopTree* u_c_loop = phase->get_loop(u_c);
2363             if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
2364               wq.push(u);
2365             }
2366           }
2367         }
2368       }
2369     }
2370   }
2371 }
2372 
2373 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
2374                                       IdealLoopTree* outer_loop, int dd, Node_List &old_new,
2375                                       Node_List& extra_data_nodes) {
2376   if (head->is_strip_mined() && mode != IgnoreStripMined) {
2377     CountedLoopNode* cl = head->as_CountedLoop();
2378     Node* l = cl->outer_loop();
2379     Node* tail = cl->outer_loop_tail();
2380     IfNode* le = cl->outer_loop_end();
2381     Node* sfpt = cl->outer_safepoint();
2382     CountedLoopEndNode* cle = cl->loopexit();
2383     CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
2384     CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
2385     Node* cle_out = cle->proj_out(false);
2386 
2387     Node* new_sfpt = nullptr;
2388     Node* new_cle_out = cle_out->clone();
2389     old_new.map(cle_out->_idx, new_cle_out);
2390     if (mode == CloneIncludesStripMined) {
2391       // clone outer loop body
2392       Node* new_l = l->clone();
2393       Node* new_tail = tail->clone();
2394       IfNode* new_le = le->clone()->as_If();
2395       new_sfpt = sfpt->clone();
2396 
2397       set_loop(new_l, outer_loop->_parent);
2398       set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
2399       set_loop(new_cle_out, outer_loop->_parent);
2400       set_idom(new_cle_out, new_cle, dd);
2401       set_loop(new_sfpt, outer_loop->_parent);
2402       set_idom(new_sfpt, new_cle_out, dd);
2403       set_loop(new_le, outer_loop->_parent);
2404       set_idom(new_le, new_sfpt, dd);
2405       set_loop(new_tail, outer_loop->_parent);
2406       set_idom(new_tail, new_le, dd);
2407       set_idom(new_cl, new_l, dd);
2408 
2409       old_new.map(l->_idx, new_l);
2410       old_new.map(tail->_idx, new_tail);
2411       old_new.map(le->_idx, new_le);
2412       old_new.map(sfpt->_idx, new_sfpt);
2413 
2414       new_l->set_req(LoopNode::LoopBackControl, new_tail);
2415       new_l->set_req(0, new_l);
2416       new_tail->set_req(0, new_le);
2417       new_le->set_req(0, new_sfpt);
2418       new_sfpt->set_req(0, new_cle_out);
2419       new_cle_out->set_req(0, new_cle);
2420       new_cl->set_req(LoopNode::EntryControl, new_l);
2421 
2422       _igvn.register_new_node_with_optimizer(new_l);
2423       _igvn.register_new_node_with_optimizer(new_tail);
2424       _igvn.register_new_node_with_optimizer(new_le);
2425     } else {
2426       Node *newhead = old_new[loop->_head->_idx];
2427       newhead->as_Loop()->clear_strip_mined();
2428       _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
2429       set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2430     }
2431     // Look at data node that were assigned a control in the outer
2432     // loop: they are kept in the outer loop by the safepoint so start
2433     // from the safepoint node's inputs.
2434     IdealLoopTree* outer_loop = get_loop(l);
2435     Node_Stack stack(2);
2436     stack.push(sfpt, 1);
2437     uint new_counter = C->unique();
2438     while (stack.size() > 0) {
2439       Node* n = stack.node();
2440       uint i = stack.index();
2441       while (i < n->req() &&
2442              (n->in(i) == nullptr ||
2443               !has_ctrl(n->in(i)) ||
2444               get_loop(get_ctrl(n->in(i))) != outer_loop ||
2445               (old_new[n->in(i)->_idx] != nullptr && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
2446         i++;
2447       }
2448       if (i < n->req()) {
2449         stack.set_index(i+1);
2450         stack.push(n->in(i), 0);
2451       } else {
2452         assert(old_new[n->_idx] == nullptr || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
2453         Node* m = n == sfpt ? new_sfpt : n->clone();
2454         if (m != nullptr) {
2455           for (uint i = 0; i < n->req(); i++) {
2456             if (m->in(i) != nullptr && old_new[m->in(i)->_idx] != nullptr) {
2457               m->set_req(i, old_new[m->in(i)->_idx]);
2458             }
2459           }
2460         } else {
2461           assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2462         }
2463         if (n != sfpt) {
2464           extra_data_nodes.push(n);
2465           _igvn.register_new_node_with_optimizer(m);
2466           assert(get_ctrl(n) == cle_out, "what other control?");
2467           set_ctrl(m, new_cle_out);
2468           old_new.map(n->_idx, m);
2469         }
2470         stack.pop();
2471       }
2472     }
2473     if (mode == CloneIncludesStripMined) {
2474       _igvn.register_new_node_with_optimizer(new_sfpt);
2475       _igvn.register_new_node_with_optimizer(new_cle_out);
2476     }
2477     // Some other transformation may have pessimistically assigned some
2478     // data nodes to the outer loop. Set their control so they are out
2479     // of the outer loop.
2480     ResourceMark rm;
2481     Unique_Node_List wq;
2482     for (uint i = 0; i < extra_data_nodes.size(); i++) {
2483       Node* old = extra_data_nodes.at(i);
2484       collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2485     }
2486 
2487     for (uint i = 0; i < loop->_body.size(); i++) {
2488       Node* old = loop->_body.at(i);
2489       collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2490     }
2491 
2492     Node* inner_out = sfpt->in(0);
2493     if (inner_out->outcnt() > 1) {
2494       collect_nodes_in_outer_loop_not_reachable_from_sfpt(inner_out, loop, outer_loop, old_new, wq, this, true);
2495     }
2496 
2497     Node* new_ctrl = cl->outer_loop_exit();
2498     assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2499     for (uint i = 0; i < wq.size(); i++) {
2500       Node* n = wq.at(i);
2501       set_ctrl(n, new_ctrl);
2502       if (n->in(0) != nullptr) {
2503         _igvn.replace_input_of(n, 0, new_ctrl);
2504       }
2505       collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
2506     }
2507   } else {
2508     Node *newhead = old_new[loop->_head->_idx];
2509     set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2510   }
2511 }
2512 
2513 //------------------------------clone_loop-------------------------------------
2514 //
2515 //                   C L O N E   A   L O O P   B O D Y
2516 //
2517 // This is the basic building block of the loop optimizations.  It clones an
2518 // entire loop body.  It makes an old_new loop body mapping; with this mapping
2519 // you can find the new-loop equivalent to an old-loop node.  All new-loop
2520 // nodes are exactly equal to their old-loop counterparts, all edges are the
2521 // same.  All exits from the old-loop now have a RegionNode that merges the
2522 // equivalent new-loop path.  This is true even for the normal "loop-exit"
2523 // condition.  All uses of loop-invariant old-loop values now come from (one
2524 // or more) Phis that merge their new-loop equivalents.
2525 //
2526 // This operation leaves the graph in an illegal state: there are two valid
2527 // control edges coming from the loop pre-header to both loop bodies.  I'll
2528 // definitely have to hack the graph after running this transform.
2529 //
2530 // From this building block I will further edit edges to perform loop peeling
2531 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2532 //
2533 // Parameter side_by_size_idom:
2534 //   When side_by_size_idom is null, the dominator tree is constructed for
2535 //      the clone loop to dominate the original.  Used in construction of
2536 //      pre-main-post loop sequence.
2537 //   When nonnull, the clone and original are side-by-side, both are
2538 //      dominated by the side_by_side_idom node.  Used in construction of
2539 //      unswitched loops.
2540 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2541                                 CloneLoopMode mode, Node* side_by_side_idom) {
2542 
2543   LoopNode* head = loop->_head->as_Loop();
2544   head->verify_strip_mined(1);
2545 
2546   if (C->do_vector_loop() && PrintOpto) {
2547     const char* mname = C->method()->name()->as_quoted_ascii();
2548     if (mname != nullptr) {
2549       tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2550     }
2551   }
2552 
2553   CloneMap& cm = C->clone_map();
2554   if (C->do_vector_loop()) {
2555     cm.set_clone_idx(cm.max_gen()+1);
2556 #ifndef PRODUCT
2557     if (PrintOpto) {
2558       tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2559       loop->dump_head();
2560     }
2561 #endif
2562   }
2563 
2564   // Step 1: Clone the loop body.  Make the old->new mapping.
2565   clone_loop_body(loop->_body, old_new, &cm);
2566 
2567   IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2568 
2569   // Step 2: Fix the edges in the new body.  If the old input is outside the
2570   // loop use it.  If the old input is INside the loop, use the corresponding
2571   // new node instead.
2572   fix_body_edges(loop->_body, loop, old_new, dd, outer_loop->_parent, false);
2573 
2574   Node_List extra_data_nodes; // data nodes in the outer strip mined loop
2575   clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2576 
2577   // Step 3: Now fix control uses.  Loop varying control uses have already
2578   // been fixed up (as part of all input edges in Step 2).  Loop invariant
2579   // control uses must be either an IfFalse or an IfTrue.  Make a merge
2580   // point to merge the old and new IfFalse/IfTrue nodes; make the use
2581   // refer to this.
2582   Node_List worklist;
2583   uint new_counter = C->unique();
2584   fix_ctrl_uses(loop->_body, loop, old_new, mode, side_by_side_idom, &cm, worklist);
2585 
2586   // Step 4: If loop-invariant use is not control, it must be dominated by a
2587   // loop exit IfFalse/IfTrue.  Find "proper" loop exit.  Make a Region
2588   // there if needed.  Make a Phi there merging old and new used values.
2589   Node_List *split_if_set = nullptr;
2590   Node_List *split_bool_set = nullptr;
2591   Node_List *split_cex_set = nullptr;
2592   fix_data_uses(loop->_body, loop, mode, outer_loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
2593 
2594   for (uint i = 0; i < extra_data_nodes.size(); i++) {
2595     Node* old = extra_data_nodes.at(i);
2596     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2597                                 split_bool_set, split_cex_set, worklist, new_counter,
2598                                 mode);
2599   }
2600 
2601   // Check for IFs that need splitting/cloning.  Happens if an IF outside of
2602   // the loop uses a condition set in the loop.  The original IF probably
2603   // takes control from one or more OLD Regions (which in turn get from NEW
2604   // Regions).  In any case, there will be a set of Phis for each merge point
2605   // from the IF up to where the original BOOL def exists the loop.
2606   finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
2607 
2608 }
2609 
2610 void PhaseIdealLoop::finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set) {
2611   if (split_if_set) {
2612     while (split_if_set->size()) {
2613       Node *iff = split_if_set->pop();
2614       uint input = iff->Opcode() == Op_AllocateArray ? AllocateNode::ValidLengthTest : 1;
2615       if (iff->in(input)->is_Phi()) {
2616         Node *b = clone_iff(iff->in(input)->as_Phi());
2617         _igvn.replace_input_of(iff, input, b);
2618       }
2619     }
2620   }
2621   if (split_bool_set) {
2622     while (split_bool_set->size()) {
2623       Node *b = split_bool_set->pop();
2624       Node *phi = b->in(1);
2625       assert(phi->is_Phi(), "");
2626       CmpNode *cmp = clone_bool((PhiNode*) phi);
2627       _igvn.replace_input_of(b, 1, cmp);
2628     }
2629   }
2630   if (split_cex_set) {
2631     while (split_cex_set->size()) {
2632       Node *b = split_cex_set->pop();
2633       assert(b->in(0)->is_Region(), "");
2634       assert(b->in(1)->is_Phi(), "");
2635       assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2636       split_up(b, b->in(0), nullptr);
2637     }
2638   }
2639 }
2640 
2641 void PhaseIdealLoop::fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
2642                                    uint new_counter, Node_List &old_new, Node_List &worklist, Node_List*& split_if_set,
2643                                    Node_List*& split_bool_set, Node_List*& split_cex_set) {
2644   for(uint i = 0; i < body.size(); i++ ) {
2645     Node* old = body.at(i);
2646     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2647                                 split_bool_set, split_cex_set, worklist, new_counter,
2648                                 mode);
2649   }
2650 }
2651 
2652 void PhaseIdealLoop::fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
2653                                    Node* side_by_side_idom, CloneMap* cm, Node_List &worklist) {
2654   LoopNode* head = loop->_head->as_Loop();
2655   for(uint i = 0; i < body.size(); i++ ) {
2656     Node* old = body.at(i);
2657     if( !old->is_CFG() ) continue;
2658 
2659     // Copy uses to a worklist, so I can munge the def-use info
2660     // with impunity.
2661     for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) {
2662       worklist.push(old->fast_out(j));
2663     }
2664 
2665     while (worklist.size()) {  // Visit all uses
2666       Node *use = worklist.pop();
2667       if (!has_node(use))  continue; // Ignore dead nodes
2668       IdealLoopTree *use_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use );
2669       if (!loop->is_member(use_loop) && use->is_CFG()) {
2670         // Both OLD and USE are CFG nodes here.
2671         assert(use->is_Proj(), "" );
2672         Node* nnn = old_new[old->_idx];
2673 
2674         Node* newuse = nullptr;
2675         if (head->is_strip_mined() && mode != IgnoreStripMined) {
2676           CountedLoopNode* cl = head->as_CountedLoop();
2677           CountedLoopEndNode* cle = cl->loopexit();
2678           Node* cle_out = cle->proj_out_or_null(false);
2679           if (use == cle_out) {
2680             IfNode* le = cl->outer_loop_end();
2681             use = le->proj_out(false);
2682             use_loop = get_loop(use);
2683             if (mode == CloneIncludesStripMined) {
2684               nnn = old_new[le->_idx];
2685             } else {
2686               newuse = old_new[cle_out->_idx];
2687             }
2688           }
2689         }
2690         if (newuse == nullptr) {
2691           newuse = use->clone();
2692         }
2693 
2694         // Clone the loop exit control projection
2695         if (C->do_vector_loop() && cm != nullptr) {
2696           cm->verify_insert_and_clone(use, newuse, cm->clone_idx());
2697         }
2698         newuse->set_req(0,nnn);
2699         _igvn.register_new_node_with_optimizer(newuse);
2700         set_loop(newuse, use_loop);
2701         set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2702 
2703         // We need a Region to merge the exit from the peeled body and the
2704         // exit from the old loop body.
2705         RegionNode *r = new RegionNode(3);
2706         uint dd_r = MIN2(dom_depth(newuse), dom_depth(use));
2707         assert(dd_r >= dom_depth(dom_lca(newuse, use)), "" );
2708 
2709         // The original user of 'use' uses 'r' instead.
2710         for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2711           Node* useuse = use->last_out(l);
2712           _igvn.rehash_node_delayed(useuse);
2713           uint uses_found = 0;
2714           if (useuse->in(0) == use) {
2715             useuse->set_req(0, r);
2716             uses_found++;
2717             if (useuse->is_CFG()) {
2718               // This is not a dom_depth > dd_r because when new
2719               // control flow is constructed by a loop opt, a node and
2720               // its dominator can end up at the same dom_depth
2721               assert(dom_depth(useuse) >= dd_r, "");
2722               set_idom(useuse, r, dom_depth(useuse));
2723             }
2724           }
2725           for (uint k = 1; k < useuse->req(); k++) {
2726             if( useuse->in(k) == use ) {
2727               useuse->set_req(k, r);
2728               uses_found++;
2729               if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2730                 // This is not a dom_depth > dd_r because when new
2731                 // control flow is constructed by a loop opt, a node
2732                 // and its dominator can end up at the same dom_depth
2733                 assert(dom_depth(useuse) >= dd_r , "");
2734                 set_idom(useuse, r, dom_depth(useuse));
2735               }
2736             }
2737           }
2738           l -= uses_found;    // we deleted 1 or more copies of this edge
2739         }
2740 
2741         assert(use->is_Proj(), "loop exit should be projection");
2742         // lazy_replace() below moves all nodes that are:
2743         // - control dependent on the loop exit or
2744         // - have control set to the loop exit
2745         // below the post-loop merge point. lazy_replace() takes a dead control as first input. To make it
2746         // possible to use it, the loop exit projection is cloned and becomes the new exit projection. The initial one
2747         // becomes dead and is "replaced" by the region.
2748         Node* use_clone = use->clone();
2749         register_control(use_clone, use_loop, idom(use), dom_depth(use));
2750         // Now finish up 'r'
2751         r->set_req(1, newuse);
2752         r->set_req(2, use_clone);
2753         _igvn.register_new_node_with_optimizer(r);
2754         set_loop(r, use_loop);
2755         set_idom(r, (side_by_side_idom == nullptr) ? newuse->in(0) : side_by_side_idom, dd_r);
2756         lazy_replace(use, r);
2757         // Map the (cloned) old use to the new merge point
2758         old_new.map(use_clone->_idx, r);
2759       } // End of if a loop-exit test
2760     }
2761   }
2762 }
2763 
2764 void PhaseIdealLoop::fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
2765                                     IdealLoopTree* parent, bool partial) {
2766   for(uint i = 0; i < body.size(); i++ ) {
2767     Node *old = body.at(i);
2768     Node *nnn = old_new[old->_idx];
2769     // Fix CFG/Loop controlling the new node
2770     if (has_ctrl(old)) {
2771       set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2772     } else {
2773       set_loop(nnn, parent);
2774       if (old->outcnt() > 0) {
2775         Node* dom = idom(old);
2776         if (old_new[dom->_idx] != nullptr) {
2777           dom = old_new[dom->_idx];
2778           set_idom(nnn, dom, dd );
2779         }
2780       }
2781     }
2782     // Correct edges to the new node
2783     for (uint j = 0; j < nnn->req(); j++) {
2784         Node *n = nnn->in(j);
2785         if (n != nullptr) {
2786           IdealLoopTree *old_in_loop = get_loop(has_ctrl(n) ? get_ctrl(n) : n);
2787           if (loop->is_member(old_in_loop)) {
2788             if (old_new[n->_idx] != nullptr) {
2789               nnn->set_req(j, old_new[n->_idx]);
2790             } else {
2791               assert(!body.contains(n), "");
2792               assert(partial, "node not cloned");
2793             }
2794           }
2795         }
2796     }
2797     _igvn.hash_find_insert(nnn);
2798   }
2799 }
2800 
2801 void PhaseIdealLoop::clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm) {
2802   for (uint i = 0; i < body.size(); i++) {
2803     Node* old = body.at(i);
2804     Node* nnn = old->clone();
2805     old_new.map(old->_idx, nnn);
2806     if (C->do_vector_loop() && cm != nullptr) {
2807       cm->verify_insert_and_clone(old, nnn, cm->clone_idx());
2808     }
2809     _igvn.register_new_node_with_optimizer(nnn);
2810   }
2811 }
2812 
2813 
2814 //---------------------- stride_of_possible_iv -------------------------------------
2815 // Looks for an iff/bool/comp with one operand of the compare
2816 // being a cycle involving an add and a phi,
2817 // with an optional truncation (left-shift followed by a right-shift)
2818 // of the add. Returns zero if not an iv.
2819 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2820   Node* trunc1 = nullptr;
2821   Node* trunc2 = nullptr;
2822   const TypeInteger* ttype = nullptr;
2823   if (!iff->is_If() || iff->in(1) == nullptr || !iff->in(1)->is_Bool()) {
2824     return 0;
2825   }
2826   BoolNode* bl = iff->in(1)->as_Bool();
2827   Node* cmp = bl->in(1);
2828   if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2829     return 0;
2830   }
2831   // Must have an invariant operand
2832   if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2833     return 0;
2834   }
2835   Node* add2 = nullptr;
2836   Node* cmp1 = cmp->in(1);
2837   if (cmp1->is_Phi()) {
2838     // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2839     Node* phi = cmp1;
2840     for (uint i = 1; i < phi->req(); i++) {
2841       Node* in = phi->in(i);
2842       Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2843                                 &trunc1, &trunc2, &ttype, T_INT);
2844       if (add && add->in(1) == phi) {
2845         add2 = add->in(2);
2846         break;
2847       }
2848     }
2849   } else {
2850     // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2851     Node* addtrunc = cmp1;
2852     Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2853                                 &trunc1, &trunc2, &ttype, T_INT);
2854     if (add && add->in(1)->is_Phi()) {
2855       Node* phi = add->in(1);
2856       for (uint i = 1; i < phi->req(); i++) {
2857         if (phi->in(i) == addtrunc) {
2858           add2 = add->in(2);
2859           break;
2860         }
2861       }
2862     }
2863   }
2864   if (add2 != nullptr) {
2865     const TypeInt* add2t = _igvn.type(add2)->is_int();
2866     if (add2t->is_con()) {
2867       return add2t->get_con();
2868     }
2869   }
2870   return 0;
2871 }
2872 
2873 
2874 //---------------------- stay_in_loop -------------------------------------
2875 // Return the (unique) control output node that's in the loop (if it exists.)
2876 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2877   Node* unique = nullptr;
2878   if (!n) return nullptr;
2879   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2880     Node* use = n->fast_out(i);
2881     if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2882       if (unique != nullptr) {
2883         return nullptr;
2884       }
2885       unique = use;
2886     }
2887   }
2888   return unique;
2889 }
2890 
2891 //------------------------------ register_node -------------------------------------
2892 // Utility to register node "n" with PhaseIdealLoop
2893 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree* loop, Node* pred, uint ddepth) {
2894   _igvn.register_new_node_with_optimizer(n);
2895   loop->_body.push(n);
2896   if (n->is_CFG()) {
2897     set_loop(n, loop);
2898     set_idom(n, pred, ddepth);
2899   } else {
2900     set_ctrl(n, pred);
2901   }
2902 }
2903 
2904 //------------------------------ proj_clone -------------------------------------
2905 // Utility to create an if-projection
2906 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2907   ProjNode* c = p->clone()->as_Proj();
2908   c->set_req(0, iff);
2909   return c;
2910 }
2911 
2912 //------------------------------ short_circuit_if -------------------------------------
2913 // Force the iff control output to be the live_proj
2914 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2915   guarantee(live_proj != nullptr, "null projection");
2916   int proj_con = live_proj->_con;
2917   assert(proj_con == 0 || proj_con == 1, "false or true projection");
2918   Node* con = intcon(proj_con);
2919   if (iff) {
2920     iff->set_req(1, con);
2921   }
2922   return con;
2923 }
2924 
2925 //------------------------------ insert_if_before_proj -------------------------------------
2926 // Insert a new if before an if projection (* - new node)
2927 //
2928 // before
2929 //           if(test)
2930 //           /     \
2931 //          v       v
2932 //    other-proj   proj (arg)
2933 //
2934 // after
2935 //           if(test)
2936 //           /     \
2937 //          /       v
2938 //         |      * proj-clone
2939 //         v          |
2940 //    other-proj      v
2941 //                * new_if(relop(cmp[IU](left,right)))
2942 //                  /  \
2943 //                 v    v
2944 //         * new-proj  proj
2945 //         (returned)
2946 //
2947 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2948   IfNode* iff = proj->in(0)->as_If();
2949   IdealLoopTree *loop = get_loop(proj);
2950   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2951   uint ddepth = dom_depth(proj);
2952 
2953   _igvn.rehash_node_delayed(iff);
2954   _igvn.rehash_node_delayed(proj);
2955 
2956   proj->set_req(0, nullptr);  // temporary disconnect
2957   ProjNode* proj2 = proj_clone(proj, iff);
2958   register_node(proj2, loop, iff, ddepth);
2959 
2960   Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2961   register_node(cmp, loop, proj2, ddepth);
2962 
2963   BoolNode* bol = new BoolNode(cmp, relop);
2964   register_node(bol, loop, proj2, ddepth);
2965 
2966   int opcode = iff->Opcode();
2967   assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2968   IfNode* new_if = IfNode::make_with_same_profile(iff, proj2, bol);
2969   register_node(new_if, loop, proj2, ddepth);
2970 
2971   proj->set_req(0, new_if); // reattach
2972   set_idom(proj, new_if, ddepth);
2973 
2974   ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2975   guarantee(new_exit != nullptr, "null exit node");
2976   register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2977 
2978   return new_exit;
2979 }
2980 
2981 //------------------------------ insert_region_before_proj -------------------------------------
2982 // Insert a region before an if projection (* - new node)
2983 //
2984 // before
2985 //           if(test)
2986 //          /      |
2987 //         v       |
2988 //       proj      v
2989 //               other-proj
2990 //
2991 // after
2992 //           if(test)
2993 //          /      |
2994 //         v       |
2995 // * proj-clone    v
2996 //         |     other-proj
2997 //         v
2998 // * new-region
2999 //         |
3000 //         v
3001 // *      dum_if
3002 //       /     \
3003 //      v       \
3004 // * dum-proj    v
3005 //              proj
3006 //
3007 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
3008   IfNode* iff = proj->in(0)->as_If();
3009   IdealLoopTree *loop = get_loop(proj);
3010   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
3011   uint ddepth = dom_depth(proj);
3012 
3013   _igvn.rehash_node_delayed(iff);
3014   _igvn.rehash_node_delayed(proj);
3015 
3016   proj->set_req(0, nullptr);  // temporary disconnect
3017   ProjNode* proj2 = proj_clone(proj, iff);
3018   register_node(proj2, loop, iff, ddepth);
3019 
3020   RegionNode* reg = new RegionNode(2);
3021   reg->set_req(1, proj2);
3022   register_node(reg, loop, iff, ddepth);
3023 
3024   IfNode* dum_if = new IfNode(reg, short_circuit_if(nullptr, proj), iff->_prob, iff->_fcnt);
3025   register_node(dum_if, loop, reg, ddepth);
3026 
3027   proj->set_req(0, dum_if); // reattach
3028   set_idom(proj, dum_if, ddepth);
3029 
3030   ProjNode* dum_proj = proj_clone(other_proj, dum_if);
3031   register_node(dum_proj, loop, dum_if, ddepth);
3032 
3033   return reg;
3034 }
3035 
3036 // Idea
3037 // ----
3038 // Partial Peeling tries to rotate the loop in such a way that it can later be turned into a counted loop. Counted loops
3039 // require a signed loop exit test. When calling this method, we've only found a suitable unsigned test to partial peel
3040 // with. Therefore, we try to split off a signed loop exit test from the unsigned test such that it can be used as new
3041 // loop exit while keeping the unsigned test unchanged and preserving the same behavior as if we've used the unsigned
3042 // test alone instead:
3043 //
3044 // Before Partial Peeling:
3045 //   Loop:
3046 //     <peeled section>
3047 //     Split off signed loop exit test
3048 //     <-- CUT HERE -->
3049 //     Unchanged unsigned loop exit test
3050 //     <rest of unpeeled section>
3051 //     goto Loop
3052 //
3053 // After Partial Peeling:
3054 //   <cloned peeled section>
3055 //   Cloned split off signed loop exit test
3056 //   Loop:
3057 //     Unchanged unsigned loop exit test
3058 //     <rest of unpeeled section>
3059 //     <peeled section>
3060 //     Split off signed loop exit test
3061 //     goto Loop
3062 //
3063 // Details
3064 // -------
3065 // Before:
3066 //          if (i <u limit)    Unsigned loop exit condition
3067 //         /       |
3068 //        v        v
3069 //   exit-proj   stay-in-loop-proj
3070 //
3071 // Split off a signed loop exit test (i.e. with CmpI) from an unsigned loop exit test (i.e. with CmpU) and insert it
3072 // before the CmpU on the stay-in-loop path and keep both tests:
3073 //
3074 //          if (i <u limit)    Signed loop exit test
3075 //        /        |
3076 //       /  if (i <u limit)    Unsigned loop exit test
3077 //      /  /       |
3078 //     v  v        v
3079 //  exit-region  stay-in-loop-proj
3080 //
3081 // Implementation
3082 // --------------
3083 // We need to make sure that the new signed loop exit test is properly inserted into the graph such that the unsigned
3084 // loop exit test still dominates the same set of control nodes, the ctrl() relation from data nodes to both loop
3085 // exit tests is preserved, and their loop nesting is correct.
3086 //
3087 // To achieve that, we clone the unsigned loop exit test completely (leave it unchanged), insert the signed loop exit
3088 // test above it and kill the original unsigned loop exit test by setting it's condition to a constant
3089 // (i.e. stay-in-loop-const in graph below) such that IGVN can fold it later:
3090 //
3091 //           if (stay-in-loop-const)  Killed original unsigned loop exit test
3092 //          /       |
3093 //         /        v
3094 //        /  if (i <  limit)          Split off signed loop exit test
3095 //       /  /       |
3096 //      /  /        v
3097 //     /  /  if (i <u limit)          Cloned unsigned loop exit test
3098 //    /  /   /      |
3099 //   v  v  v        |
3100 //  exit-region     |
3101 //        |         |
3102 //    dummy-if      |
3103 //     /  |         |
3104 // dead   |         |
3105 //        v         v
3106 //   exit-proj   stay-in-loop-proj
3107 //
3108 // Note: The dummy-if is inserted to create a region to merge the loop exits between the original to be killed unsigned
3109 //       loop exit test and its exit projection while keeping the exit projection (also see insert_region_before_proj()).
3110 //
3111 // Requirements
3112 // ------------
3113 // Note that we can only split off a signed loop exit test from the unsigned loop exit test when the behavior is exactly
3114 // the same as before with only a single unsigned test. This is only possible if certain requirements are met.
3115 // Otherwise, we need to bail out (see comments in the code below).
3116 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree* loop) {
3117   const bool Signed   = true;
3118   const bool Unsigned = false;
3119 
3120   BoolNode* bol = if_cmpu->in(1)->as_Bool();
3121   if (bol->_test._test != BoolTest::lt) {
3122     return nullptr;
3123   }
3124   CmpNode* cmpu = bol->in(1)->as_Cmp();
3125   assert(cmpu->Opcode() == Op_CmpU, "must be unsigned comparison");
3126 
3127   int stride = stride_of_possible_iv(if_cmpu);
3128   if (stride == 0) {
3129     return nullptr;
3130   }
3131 
3132   Node* lp_proj = stay_in_loop(if_cmpu, loop);
3133   guarantee(lp_proj != nullptr, "null loop node");
3134 
3135   ProjNode* lp_continue = lp_proj->as_Proj();
3136   ProjNode* lp_exit     = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
3137   if (!lp_exit->is_IfFalse()) {
3138     // The loop exit condition is (i <u limit) ==> (i >= 0 && i < limit).
3139     // We therefore can't add a single exit condition.
3140     return nullptr;
3141   }
3142   // The unsigned loop exit condition is
3143   //   !(i <u  limit)
3144   // =   i >=u limit
3145   //
3146   // First, we note that for any x for which
3147   //   0 <= x <= INT_MAX
3148   // we can convert x to an unsigned int and still get the same guarantee:
3149   //   0 <=  (uint) x <=  INT_MAX = (uint) INT_MAX
3150   //   0 <=u (uint) x <=u INT_MAX = (uint) INT_MAX   (LEMMA)
3151   //
3152   // With that in mind, if
3153   //   limit >= 0             (COND)
3154   // then the unsigned loop exit condition
3155   //   i >=u limit            (ULE)
3156   // is equivalent to
3157   //   i < 0 || i >= limit    (SLE-full)
3158   // because either i is negative and therefore always greater than MAX_INT when converting to unsigned
3159   //   (uint) i >=u MAX_INT >= limit >= 0
3160   // or otherwise
3161   //   i >= limit >= 0
3162   // holds due to (LEMMA).
3163   //
3164   // For completeness, a counterexample with limit < 0:
3165   // Assume i = -3 and limit = -2:
3166   //   i  < 0
3167   //   -2 < 0
3168   // is true and thus also "i < 0 || i >= limit". But
3169   //   i  >=u limit
3170   //   -3 >=u -2
3171   // is false.
3172   Node* limit = cmpu->in(2);
3173   const TypeInt* type_limit = _igvn.type(limit)->is_int();
3174   if (type_limit->_lo < 0) {
3175     return nullptr;
3176   }
3177 
3178   // We prove below that we can extract a single signed loop exit condition from (SLE-full), depending on the stride:
3179   //   stride < 0:
3180   //     i < 0        (SLE = SLE-negative)
3181   //   stride > 0:
3182   //     i >= limit   (SLE = SLE-positive)
3183   // such that we have the following graph before Partial Peeling with stride > 0 (similar for stride < 0):
3184   //
3185   // Loop:
3186   //   <peeled section>
3187   //   i >= limit    (SLE-positive)
3188   //   <-- CUT HERE -->
3189   //   i >=u limit   (ULE)
3190   //   <rest of unpeeled section>
3191   //   goto Loop
3192   //
3193   // We exit the loop if:
3194   //   (SLE) is true OR (ULE) is true
3195   // However, if (SLE) is true then (ULE) also needs to be true to ensure the exact same behavior. Otherwise, we wrongly
3196   // exit a loop that should not have been exited if we did not apply Partial Peeling. More formally, we need to ensure:
3197   //   (SLE) IMPLIES (ULE)
3198   // This indeed holds when (COND) is given:
3199   // - stride > 0:
3200   //       i >=  limit             // (SLE = SLE-positive)
3201   //       i >=  limit >= 0        // (COND)
3202   //       i >=u limit >= 0        // (LEMMA)
3203   //     which is the unsigned loop exit condition (ULE).
3204   // - stride < 0:
3205   //       i        <  0           // (SLE = SLE-negative)
3206   //       (uint) i >u MAX_INT     // (NEG) all negative values are greater than MAX_INT when converted to unsigned
3207   //       MAX_INT >= limit >= 0   // (COND)
3208   //       MAX_INT >=u limit >= 0  // (LEMMA)
3209   //     and thus from (NEG) and (LEMMA):
3210   //       i >=u limit
3211   //     which is the unsigned loop exit condition (ULE).
3212   //
3213   //
3214   // After Partial Peeling, we have the following structure for stride > 0 (similar for stride < 0):
3215   //   <cloned peeled section>
3216   //   i >= limit (SLE-positive)
3217   //   Loop:
3218   //     i >=u limit (ULE)
3219   //     <rest of unpeeled section>
3220   //     <peeled section>
3221   //     i >= limit (SLE-positive)
3222   //     goto Loop
3223   Node* rhs_cmpi;
3224   if (stride > 0) {
3225     rhs_cmpi = limit; // For i >= limit
3226   } else {
3227     rhs_cmpi = makecon(TypeInt::ZERO); // For i < 0
3228   }
3229   // Create a new region on the exit path
3230   RegionNode* reg = insert_region_before_proj(lp_exit);
3231   guarantee(reg != nullptr, "null region node");
3232 
3233   // Clone the if-cmpu-true-false using a signed compare
3234   BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
3235   ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, rhs_cmpi, lp_continue);
3236   reg->add_req(cmpi_exit);
3237 
3238   // Clone the if-cmpu-true-false
3239   BoolTest::mask rel_u = bol->_test._test;
3240   ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
3241   reg->add_req(cmpu_exit);
3242 
3243   // Force original if to stay in loop.
3244   short_circuit_if(if_cmpu, lp_continue);
3245 
3246   return cmpi_exit->in(0)->as_If();
3247 }
3248 
3249 //------------------------------ remove_cmpi_loop_exit -------------------------------------
3250 // Remove a previously inserted signed compare loop exit.
3251 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
3252   Node* lp_proj = stay_in_loop(if_cmp, loop);
3253   assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
3254          stay_in_loop(lp_proj, loop)->is_If() &&
3255          stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
3256   Node* con = makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
3257   if_cmp->set_req(1, con);
3258 }
3259 
3260 //------------------------------ scheduled_nodelist -------------------------------------
3261 // Create a post order schedule of nodes that are in the
3262 // "member" set.  The list is returned in "sched".
3263 // The first node in "sched" is the loop head, followed by
3264 // nodes which have no inputs in the "member" set, and then
3265 // followed by the nodes that have an immediate input dependence
3266 // on a node in "sched".
3267 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
3268 
3269   assert(member.test(loop->_head->_idx), "loop head must be in member set");
3270   VectorSet visited;
3271   Node_Stack nstack(loop->_body.size());
3272 
3273   Node* n  = loop->_head;  // top of stack is cached in "n"
3274   uint idx = 0;
3275   visited.set(n->_idx);
3276 
3277   // Initially push all with no inputs from within member set
3278   for(uint i = 0; i < loop->_body.size(); i++ ) {
3279     Node *elt = loop->_body.at(i);
3280     if (member.test(elt->_idx)) {
3281       bool found = false;
3282       for (uint j = 0; j < elt->req(); j++) {
3283         Node* def = elt->in(j);
3284         if (def && member.test(def->_idx) && def != elt) {
3285           found = true;
3286           break;
3287         }
3288       }
3289       if (!found && elt != loop->_head) {
3290         nstack.push(n, idx);
3291         n = elt;
3292         assert(!visited.test(n->_idx), "not seen yet");
3293         visited.set(n->_idx);
3294       }
3295     }
3296   }
3297 
3298   // traverse out's that are in the member set
3299   while (true) {
3300     if (idx < n->outcnt()) {
3301       Node* use = n->raw_out(idx);
3302       idx++;
3303       if (!visited.test_set(use->_idx)) {
3304         if (member.test(use->_idx)) {
3305           nstack.push(n, idx);
3306           n = use;
3307           idx = 0;
3308         }
3309       }
3310     } else {
3311       // All outputs processed
3312       sched.push(n);
3313       if (nstack.is_empty()) break;
3314       n   = nstack.node();
3315       idx = nstack.index();
3316       nstack.pop();
3317     }
3318   }
3319 }
3320 
3321 
3322 //------------------------------ has_use_in_set -------------------------------------
3323 // Has a use in the vector set
3324 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
3325   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3326     Node* use = n->fast_out(j);
3327     if (vset.test(use->_idx)) {
3328       return true;
3329     }
3330   }
3331   return false;
3332 }
3333 
3334 
3335 //------------------------------ has_use_internal_to_set -------------------------------------
3336 // Has use internal to the vector set (ie. not in a phi at the loop head)
3337 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
3338   Node* head  = loop->_head;
3339   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3340     Node* use = n->fast_out(j);
3341     if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
3342       return true;
3343     }
3344   }
3345   return false;
3346 }
3347 
3348 
3349 //------------------------------ clone_for_use_outside_loop -------------------------------------
3350 // clone "n" for uses that are outside of loop
3351 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
3352   int cloned = 0;
3353   assert(worklist.size() == 0, "should be empty");
3354   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3355     Node* use = n->fast_out(j);
3356     if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
3357       worklist.push(use);
3358     }
3359   }
3360 
3361   if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor,
3362                           "Too many clones required in clone_for_use_outside_loop in partial peeling")) {
3363     return -1;
3364   }
3365 
3366   while( worklist.size() ) {
3367     Node *use = worklist.pop();
3368     if (!has_node(use) || use->in(0) == C->top()) continue;
3369     uint j;
3370     for (j = 0; j < use->req(); j++) {
3371       if (use->in(j) == n) break;
3372     }
3373     assert(j < use->req(), "must be there");
3374 
3375     // clone "n" and insert it between the inputs of "n" and the use outside the loop
3376     Node* n_clone = n->clone();
3377     _igvn.replace_input_of(use, j, n_clone);
3378     cloned++;
3379     Node* use_c;
3380     if (!use->is_Phi()) {
3381       use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
3382     } else {
3383       // Use in a phi is considered a use in the associated predecessor block
3384       use_c = use->in(0)->in(j);
3385     }
3386     set_ctrl(n_clone, use_c);
3387     assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
3388     get_loop(use_c)->_body.push(n_clone);
3389     _igvn.register_new_node_with_optimizer(n_clone);
3390 #ifndef PRODUCT
3391     if (TracePartialPeeling) {
3392       tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
3393     }
3394 #endif
3395   }
3396   return cloned;
3397 }
3398 
3399 
3400 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
3401 // clone "n" for special uses that are in the not_peeled region.
3402 // If these def-uses occur in separate blocks, the code generator
3403 // marks the method as not compilable.  For example, if a "BoolNode"
3404 // is in a different basic block than the "IfNode" that uses it, then
3405 // the compilation is aborted in the code generator.
3406 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
3407                                                         VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
3408   if (n->is_Phi() || n->is_Load()) {
3409     return;
3410   }
3411   assert(worklist.size() == 0, "should be empty");
3412   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3413     Node* use = n->fast_out(j);
3414     if ( not_peel.test(use->_idx) &&
3415          (use->is_If() || use->is_CMove() || use->is_Bool()) &&
3416          use->in(1) == n)  {
3417       worklist.push(use);
3418     }
3419   }
3420   if (worklist.size() > 0) {
3421     // clone "n" and insert it between inputs of "n" and the use
3422     Node* n_clone = n->clone();
3423     loop->_body.push(n_clone);
3424     _igvn.register_new_node_with_optimizer(n_clone);
3425     set_ctrl(n_clone, get_ctrl(n));
3426     sink_list.push(n_clone);
3427     not_peel.set(n_clone->_idx);
3428 #ifndef PRODUCT
3429     if (TracePartialPeeling) {
3430       tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
3431     }
3432 #endif
3433     while( worklist.size() ) {
3434       Node *use = worklist.pop();
3435       _igvn.rehash_node_delayed(use);
3436       for (uint j = 1; j < use->req(); j++) {
3437         if (use->in(j) == n) {
3438           use->set_req(j, n_clone);
3439         }
3440       }
3441     }
3442   }
3443 }
3444 
3445 
3446 //------------------------------ insert_phi_for_loop -------------------------------------
3447 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
3448 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
3449   Node *phi = PhiNode::make(lp, back_edge_val);
3450   phi->set_req(LoopNode::EntryControl, lp_entry_val);
3451   // Use existing phi if it already exists
3452   Node *hit = _igvn.hash_find_insert(phi);
3453   if( hit == nullptr ) {
3454     _igvn.register_new_node_with_optimizer(phi);
3455     set_ctrl(phi, lp);
3456   } else {
3457     // Remove the new phi from the graph and use the hit
3458     _igvn.remove_dead_node(phi);
3459     phi = hit;
3460   }
3461   _igvn.replace_input_of(use, idx, phi);
3462 }
3463 
3464 #ifdef ASSERT
3465 //------------------------------ is_valid_loop_partition -------------------------------------
3466 // Validate the loop partition sets: peel and not_peel
3467 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
3468                                               VectorSet& not_peel ) {
3469   uint i;
3470   // Check that peel_list entries are in the peel set
3471   for (i = 0; i < peel_list.size(); i++) {
3472     if (!peel.test(peel_list.at(i)->_idx)) {
3473       return false;
3474     }
3475   }
3476   // Check at loop members are in one of peel set or not_peel set
3477   for (i = 0; i < loop->_body.size(); i++ ) {
3478     Node *def  = loop->_body.at(i);
3479     uint di = def->_idx;
3480     // Check that peel set elements are in peel_list
3481     if (peel.test(di)) {
3482       if (not_peel.test(di)) {
3483         return false;
3484       }
3485       // Must be in peel_list also
3486       bool found = false;
3487       for (uint j = 0; j < peel_list.size(); j++) {
3488         if (peel_list.at(j)->_idx == di) {
3489           found = true;
3490           break;
3491         }
3492       }
3493       if (!found) {
3494         return false;
3495       }
3496     } else if (not_peel.test(di)) {
3497       if (peel.test(di)) {
3498         return false;
3499       }
3500     } else {
3501       return false;
3502     }
3503   }
3504   return true;
3505 }
3506 
3507 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
3508 // Ensure a use outside of loop is of the right form
3509 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
3510   Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3511   return (use->is_Phi() &&
3512           use_c->is_Region() && use_c->req() == 3 &&
3513           (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
3514            use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
3515            use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
3516           loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
3517 }
3518 
3519 //------------------------------ is_valid_clone_loop_form -------------------------------------
3520 // Ensure that all uses outside of loop are of the right form
3521 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
3522                                                uint orig_exit_idx, uint clone_exit_idx) {
3523   uint len = peel_list.size();
3524   for (uint i = 0; i < len; i++) {
3525     Node *def = peel_list.at(i);
3526 
3527     for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3528       Node *use = def->fast_out(j);
3529       Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3530       if (!loop->is_member(get_loop(use_c))) {
3531         // use is not in the loop, check for correct structure
3532         if (use->in(0) == def) {
3533           // Okay
3534         } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
3535           return false;
3536         }
3537       }
3538     }
3539   }
3540   return true;
3541 }
3542 #endif
3543 
3544 //------------------------------ partial_peel -------------------------------------
3545 // Partially peel (aka loop rotation) the top portion of a loop (called
3546 // the peel section below) by cloning it and placing one copy just before
3547 // the new loop head and the other copy at the bottom of the new loop.
3548 //
3549 //    before                       after                where it came from
3550 //
3551 //    stmt1                        stmt1
3552 //  loop:                          stmt2                     clone
3553 //    stmt2                        if condA goto exitA       clone
3554 //    if condA goto exitA        new_loop:                   new
3555 //    stmt3                        stmt3                     clone
3556 //    if !condB goto loop          if condB goto exitB       clone
3557 //  exitB:                         stmt2                     orig
3558 //    stmt4                        if !condA goto new_loop   orig
3559 //  exitA:                         goto exitA
3560 //                               exitB:
3561 //                                 stmt4
3562 //                               exitA:
3563 //
3564 // Step 1: find the cut point: an exit test on probable
3565 //         induction variable.
3566 // Step 2: schedule (with cloning) operations in the peel
3567 //         section that can be executed after the cut into
3568 //         the section that is not peeled.  This may need
3569 //         to clone operations into exit blocks.  For
3570 //         instance, a reference to A[i] in the not-peel
3571 //         section and a reference to B[i] in an exit block
3572 //         may cause a left-shift of i by 2 to be placed
3573 //         in the peel block.  This step will clone the left
3574 //         shift into the exit block and sink the left shift
3575 //         from the peel to the not-peel section.
3576 // Step 3: clone the loop, retarget the control, and insert
3577 //         phis for values that are live across the new loop
3578 //         head.  This is very dependent on the graph structure
3579 //         from clone_loop.  It creates region nodes for
3580 //         exit control and associated phi nodes for values
3581 //         flow out of the loop through that exit.  The region
3582 //         node is dominated by the clone's control projection.
3583 //         So the clone's peel section is placed before the
3584 //         new loop head, and the clone's not-peel section is
3585 //         forms the top part of the new loop.  The original
3586 //         peel section forms the tail of the new loop.
3587 // Step 4: update the dominator tree and recompute the
3588 //         dominator depth.
3589 //
3590 //                   orig
3591 //
3592 //                   stmt1
3593 //                     |
3594 //                     v
3595 //                 predicates
3596 //                     |
3597 //                     v
3598 //                   loop<----+
3599 //                     |      |
3600 //                   stmt2    |
3601 //                     |      |
3602 //                     v      |
3603 //                    ifA     |
3604 //                   / |      |
3605 //                  v  v      |
3606 //               false true   ^  <-- last_peel
3607 //               /     |      |
3608 //              /   ===|==cut |
3609 //             /     stmt3    |  <-- first_not_peel
3610 //            /        |      |
3611 //            |        v      |
3612 //            v       ifB     |
3613 //          exitA:   / \      |
3614 //                  /   \     |
3615 //                 v     v    |
3616 //               false true   |
3617 //               /       \    |
3618 //              /         ----+
3619 //             |
3620 //             v
3621 //           exitB:
3622 //           stmt4
3623 //
3624 //
3625 //            after clone loop
3626 //
3627 //                   stmt1
3628 //                     |
3629 //                     v
3630 //                predicates
3631 //                 /       \
3632 //        clone   /         \   orig
3633 //               /           \
3634 //              /             \
3635 //             v               v
3636 //   +---->loop                loop<----+
3637 //   |      |                    |      |
3638 //   |    stmt2                stmt2    |
3639 //   |      |                    |      |
3640 //   |      v                    v      |
3641 //   |      ifA                 ifA     |
3642 //   |      | \                / |      |
3643 //   |      v  v              v  v      |
3644 //   ^    true  false      false true   ^  <-- last_peel
3645 //   |      |   ^   \       /    |      |
3646 //   | cut==|==  \   \     /  ===|==cut |
3647 //   |    stmt3   \   \   /    stmt3    |  <-- first_not_peel
3648 //   |      |    dom   | |       |      |
3649 //   |      v      \  1v v2      v      |
3650 //   |      ifB     regionA     ifB     |
3651 //   |      / \        |       / \      |
3652 //   |     /   \       v      /   \     |
3653 //   |    v     v    exitA:  v     v    |
3654 //   |    true  false      false true   |
3655 //   |    /     ^   \      /       \    |
3656 //   +----       \   \    /         ----+
3657 //               dom  \  /
3658 //                 \  1v v2
3659 //                  regionB
3660 //                     |
3661 //                     v
3662 //                   exitB:
3663 //                   stmt4
3664 //
3665 //
3666 //           after partial peel
3667 //
3668 //                  stmt1
3669 //                     |
3670 //                     v
3671 //                predicates
3672 //                 /
3673 //        clone   /             orig
3674 //               /          TOP
3675 //              /             \
3676 //             v               v
3677 //    TOP->loop                loop----+
3678 //          |                    |      |
3679 //        stmt2                stmt2    |
3680 //          |                    |      |
3681 //          v                    v      |
3682 //          ifA                 ifA     |
3683 //          | \                / |      |
3684 //          v  v              v  v      |
3685 //        true  false      false true   |     <-- last_peel
3686 //          |   ^   \       /    +------|---+
3687 //  +->newloop   \   \     /  === ==cut |   |
3688 //  |     stmt3   \   \   /     TOP     |   |
3689 //  |       |    dom   | |      stmt3   |   | <-- first_not_peel
3690 //  |       v      \  1v v2      v      |   |
3691 //  |       ifB     regionA     ifB     ^   v
3692 //  |       / \        |       / \      |   |
3693 //  |      /   \       v      /   \     |   |
3694 //  |     v     v    exitA:  v     v    |   |
3695 //  |     true  false      false true   |   |
3696 //  |     /     ^   \      /       \    |   |
3697 //  |    |       \   \    /         v   |   |
3698 //  |    |       dom  \  /         TOP  |   |
3699 //  |    |         \  1v v2             |   |
3700 //  ^    v          regionB             |   |
3701 //  |    |             |                |   |
3702 //  |    |             v                ^   v
3703 //  |    |           exitB:             |   |
3704 //  |    |           stmt4              |   |
3705 //  |    +------------>-----------------+   |
3706 //  |                                       |
3707 //  +-----------------<---------------------+
3708 //
3709 //
3710 //              final graph
3711 //
3712 //                  stmt1
3713 //                    |
3714 //                    v
3715 //                predicates
3716 //                    |
3717 //                    v
3718 //                  stmt2 clone
3719 //                    |
3720 //                    v
3721 //         ........> ifA clone
3722 //         :        / |
3723 //        dom      /  |
3724 //         :      v   v
3725 //         :  false   true
3726 //         :  |       |
3727 //         :  |       v
3728 //         :  |    newloop<-----+
3729 //         :  |        |        |
3730 //         :  |     stmt3 clone |
3731 //         :  |        |        |
3732 //         :  |        v        |
3733 //         :  |       ifB       |
3734 //         :  |      / \        |
3735 //         :  |     v   v       |
3736 //         :  |  false true     |
3737 //         :  |   |     |       |
3738 //         :  |   v    stmt2    |
3739 //         :  | exitB:  |       |
3740 //         :  | stmt4   v       |
3741 //         :  |       ifA orig  |
3742 //         :  |      /  \       |
3743 //         :  |     /    \      |
3744 //         :  |    v     v      |
3745 //         :  |  false  true    |
3746 //         :  |  /        \     |
3747 //         :  v  v         -----+
3748 //          RegionA
3749 //             |
3750 //             v
3751 //           exitA
3752 //
3753 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3754 
3755   assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3756   if (!loop->_head->is_Loop()) {
3757     return false;
3758   }
3759   LoopNode *head = loop->_head->as_Loop();
3760 
3761   if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3762     return false;
3763   }
3764 
3765   // Check for complex exit control
3766   for (uint ii = 0; ii < loop->_body.size(); ii++) {
3767     Node *n = loop->_body.at(ii);
3768     int opc = n->Opcode();
3769     if (n->is_Call()        ||
3770         opc == Op_Catch     ||
3771         opc == Op_CatchProj ||
3772         opc == Op_Jump      ||
3773         opc == Op_JumpProj) {
3774 #ifndef PRODUCT
3775       if (TracePartialPeeling) {
3776         tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3777       }
3778 #endif
3779       return false;
3780     }
3781   }
3782 
3783   int dd = dom_depth(head);
3784 
3785   // Step 1: find cut point
3786 
3787   // Walk up dominators to loop head looking for first loop exit
3788   // which is executed on every path thru loop.
3789   IfNode *peel_if = nullptr;
3790   IfNode *peel_if_cmpu = nullptr;
3791 
3792   Node *iff = loop->tail();
3793   while (iff != head) {
3794     if (iff->is_If()) {
3795       Node *ctrl = get_ctrl(iff->in(1));
3796       if (ctrl->is_top()) return false; // Dead test on live IF.
3797       // If loop-varying exit-test, check for induction variable
3798       if (loop->is_member(get_loop(ctrl)) &&
3799           loop->is_loop_exit(iff) &&
3800           is_possible_iv_test(iff)) {
3801         Node* cmp = iff->in(1)->in(1);
3802         if (cmp->Opcode() == Op_CmpI) {
3803           peel_if = iff->as_If();
3804         } else {
3805           assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3806           peel_if_cmpu = iff->as_If();
3807         }
3808       }
3809     }
3810     iff = idom(iff);
3811   }
3812 
3813   // Prefer signed compare over unsigned compare.
3814   IfNode* new_peel_if = nullptr;
3815   if (peel_if == nullptr) {
3816     if (!PartialPeelAtUnsignedTests || peel_if_cmpu == nullptr) {
3817       return false;   // No peel point found
3818     }
3819     new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3820     if (new_peel_if == nullptr) {
3821       return false;   // No peel point found
3822     }
3823     peel_if = new_peel_if;
3824   }
3825   Node* last_peel        = stay_in_loop(peel_if, loop);
3826   Node* first_not_peeled = stay_in_loop(last_peel, loop);
3827   if (first_not_peeled == nullptr || first_not_peeled == head) {
3828     return false;
3829   }
3830 
3831 #ifndef PRODUCT
3832   if (TraceLoopOpts) {
3833     tty->print("PartialPeel  ");
3834     loop->dump_head();
3835   }
3836 
3837   if (TracePartialPeeling) {
3838     tty->print_cr("before partial peel one iteration");
3839     Node_List wl;
3840     Node* t = head->in(2);
3841     while (true) {
3842       wl.push(t);
3843       if (t == head) break;
3844       t = idom(t);
3845     }
3846     while (wl.size() > 0) {
3847       Node* tt = wl.pop();
3848       tt->dump();
3849       if (tt == last_peel) tty->print_cr("-- cut --");
3850     }
3851   }
3852 #endif
3853 
3854   C->print_method(PHASE_BEFORE_PARTIAL_PEELING, 4, head);
3855 
3856   VectorSet peel;
3857   VectorSet not_peel;
3858   Node_List peel_list;
3859   Node_List worklist;
3860   Node_List sink_list;
3861 
3862   uint estimate = loop->est_loop_clone_sz(1);
3863   if (exceeding_node_budget(estimate)) {
3864     return false;
3865   }
3866 
3867   // Set of cfg nodes to peel are those that are executable from
3868   // the head through last_peel.
3869   assert(worklist.size() == 0, "should be empty");
3870   worklist.push(head);
3871   peel.set(head->_idx);
3872   while (worklist.size() > 0) {
3873     Node *n = worklist.pop();
3874     if (n != last_peel) {
3875       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3876         Node* use = n->fast_out(j);
3877         if (use->is_CFG() &&
3878             loop->is_member(get_loop(use)) &&
3879             !peel.test_set(use->_idx)) {
3880           worklist.push(use);
3881         }
3882       }
3883     }
3884   }
3885 
3886   // Set of non-cfg nodes to peel are those that are control
3887   // dependent on the cfg nodes.
3888   for (uint i = 0; i < loop->_body.size(); i++) {
3889     Node *n = loop->_body.at(i);
3890     Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3891     if (peel.test(n_c->_idx)) {
3892       peel.set(n->_idx);
3893     } else {
3894       not_peel.set(n->_idx);
3895     }
3896   }
3897 
3898   // Step 2: move operations from the peeled section down into the
3899   //         not-peeled section
3900 
3901   // Get a post order schedule of nodes in the peel region
3902   // Result in right-most operand.
3903   scheduled_nodelist(loop, peel, peel_list);
3904 
3905   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3906 
3907   // For future check for too many new phis
3908   uint old_phi_cnt = 0;
3909   for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3910     Node* use = head->fast_out(j);
3911     if (use->is_Phi()) old_phi_cnt++;
3912   }
3913 
3914 #ifndef PRODUCT
3915   if (TracePartialPeeling) {
3916     tty->print_cr("\npeeled list");
3917   }
3918 #endif
3919 
3920   // Evacuate nodes in peel region into the not_peeled region if possible
3921   bool too_many_clones = false;
3922   uint new_phi_cnt = 0;
3923   uint cloned_for_outside_use = 0;
3924   for (uint i = 0; i < peel_list.size();) {
3925     Node* n = peel_list.at(i);
3926 #ifndef PRODUCT
3927   if (TracePartialPeeling) n->dump();
3928 #endif
3929     bool incr = true;
3930     if (!n->is_CFG()) {
3931       if (has_use_in_set(n, not_peel)) {
3932         // If not used internal to the peeled region,
3933         // move "n" from peeled to not_peeled region.
3934         if (!has_use_internal_to_set(n, peel, loop)) {
3935           // if not pinned and not a load (which maybe anti-dependent on a store)
3936           // and not a CMove (Matcher expects only bool->cmove).
3937           if (n->in(0) == nullptr && !n->is_Load() && !n->is_CMove()) {
3938             int new_clones = clone_for_use_outside_loop(loop, n, worklist);
3939             if (C->failing()) return false;
3940             if (new_clones == -1) {
3941               too_many_clones = true;
3942               break;
3943             }
3944             cloned_for_outside_use += new_clones;
3945             sink_list.push(n);
3946             peel.remove(n->_idx);
3947             not_peel.set(n->_idx);
3948             peel_list.remove(i);
3949             incr = false;
3950 #ifndef PRODUCT
3951             if (TracePartialPeeling) {
3952               tty->print_cr("sink to not_peeled region: %d newbb: %d",
3953                             n->_idx, get_ctrl(n)->_idx);
3954             }
3955 #endif
3956           }
3957         } else {
3958           // Otherwise check for special def-use cases that span
3959           // the peel/not_peel boundary such as bool->if
3960           clone_for_special_use_inside_loop(loop, n, not_peel, sink_list, worklist);
3961           new_phi_cnt++;
3962         }
3963       }
3964     }
3965     if (incr) i++;
3966   }
3967 
3968   estimate += cloned_for_outside_use + new_phi_cnt;
3969   bool exceed_node_budget = !may_require_nodes(estimate);
3970   bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;
3971 
3972   if (too_many_clones || exceed_node_budget || exceed_phi_limit) {
3973 #ifndef PRODUCT
3974     if (TracePartialPeeling && exceed_phi_limit) {
3975       tty->print_cr("\nToo many new phis: %d  old %d new cmpi: %c",
3976                     new_phi_cnt, old_phi_cnt, new_peel_if != nullptr?'T':'F');
3977     }
3978 #endif
3979     if (new_peel_if != nullptr) {
3980       remove_cmpi_loop_exit(new_peel_if, loop);
3981     }
3982     // Inhibit more partial peeling on this loop
3983     assert(!head->is_partial_peel_loop(), "not partial peeled");
3984     head->mark_partial_peel_failed();
3985     if (cloned_for_outside_use > 0) {
3986       // Terminate this round of loop opts because
3987       // the graph outside this loop was changed.
3988       C->set_major_progress();
3989       return true;
3990     }
3991     return false;
3992   }
3993 
3994   // Step 3: clone loop, retarget control, and insert new phis
3995 
3996   // Create new loop head for new phis and to hang
3997   // the nodes being moved (sinked) from the peel region.
3998   LoopNode* new_head = new LoopNode(last_peel, last_peel);
3999   new_head->set_unswitch_count(head->unswitch_count()); // Preserve
4000   _igvn.register_new_node_with_optimizer(new_head);
4001   assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
4002   _igvn.replace_input_of(first_not_peeled, 0, new_head);
4003   set_loop(new_head, loop);
4004   loop->_body.push(new_head);
4005   not_peel.set(new_head->_idx);
4006   set_idom(new_head, last_peel, dom_depth(first_not_peeled));
4007   set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
4008 
4009   while (sink_list.size() > 0) {
4010     Node* n = sink_list.pop();
4011     set_ctrl(n, new_head);
4012   }
4013 
4014   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
4015 
4016   clone_loop(loop, old_new, dd, IgnoreStripMined);
4017 
4018   const uint clone_exit_idx = 1;
4019   const uint orig_exit_idx  = 2;
4020   assert(is_valid_clone_loop_form(loop, peel_list, orig_exit_idx, clone_exit_idx), "bad clone loop");
4021 
4022   Node* head_clone             = old_new[head->_idx];
4023   LoopNode* new_head_clone     = old_new[new_head->_idx]->as_Loop();
4024   Node* orig_tail_clone        = head_clone->in(2);
4025 
4026   // Add phi if "def" node is in peel set and "use" is not
4027 
4028   for (uint i = 0; i < peel_list.size(); i++) {
4029     Node *def  = peel_list.at(i);
4030     if (!def->is_CFG()) {
4031       for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
4032         Node *use = def->fast_out(j);
4033         if (has_node(use) && use->in(0) != C->top() &&
4034             (!peel.test(use->_idx) ||
4035              (use->is_Phi() && use->in(0) == head)) ) {
4036           worklist.push(use);
4037         }
4038       }
4039       while( worklist.size() ) {
4040         Node *use = worklist.pop();
4041         for (uint j = 1; j < use->req(); j++) {
4042           Node* n = use->in(j);
4043           if (n == def) {
4044 
4045             // "def" is in peel set, "use" is not in peel set
4046             // or "use" is in the entry boundary (a phi) of the peel set
4047 
4048             Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
4049 
4050             if ( loop->is_member(get_loop( use_c )) ) {
4051               // use is in loop
4052               if (old_new[use->_idx] != nullptr) { // null for dead code
4053                 Node* use_clone = old_new[use->_idx];
4054                 _igvn.replace_input_of(use, j, C->top());
4055                 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
4056               }
4057             } else {
4058               assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
4059               // use is not in the loop, check if the live range includes the cut
4060               Node* lp_if = use_c->in(orig_exit_idx)->in(0);
4061               if (not_peel.test(lp_if->_idx)) {
4062                 assert(j == orig_exit_idx, "use from original loop");
4063                 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
4064               }
4065             }
4066           }
4067         }
4068       }
4069     }
4070   }
4071 
4072   // Step 3b: retarget control
4073 
4074   // Redirect control to the new loop head if a cloned node in
4075   // the not_peeled region has control that points into the peeled region.
4076   // This necessary because the cloned peeled region will be outside
4077   // the loop.
4078   //                            from    to
4079   //          cloned-peeled    <---+
4080   //    new_head_clone:            |    <--+
4081   //          cloned-not_peeled  in(0)    in(0)
4082   //          orig-peeled
4083 
4084   for (uint i = 0; i < loop->_body.size(); i++) {
4085     Node *n = loop->_body.at(i);
4086     if (!n->is_CFG()           && n->in(0) != nullptr        &&
4087         not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
4088       Node* n_clone = old_new[n->_idx];
4089       if (n_clone->depends_only_on_test()) {
4090         // Pin array access nodes: control is updated here to the loop head. If, after some transformations, the
4091         // backedge is removed, an array load could become dependent on a condition that's not a range check for that
4092         // access. If that condition is replaced by an identical dominating one, then an unpinned load would risk
4093         // floating above its range check.
4094         Node* pinned_clone = n_clone->pin_array_access_node();
4095         if (pinned_clone != nullptr) {
4096           register_new_node_with_ctrl_of(pinned_clone, n_clone);
4097           old_new.map(n->_idx, pinned_clone);
4098           _igvn.replace_node(n_clone, pinned_clone);
4099           n_clone = pinned_clone;
4100         }
4101       }
4102       _igvn.replace_input_of(n_clone, 0, new_head_clone);
4103     }
4104   }
4105 
4106   // Backedge of the surviving new_head (the clone) is original last_peel
4107   _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
4108 
4109   // Cut first node in original not_peel set
4110   _igvn.rehash_node_delayed(new_head);                     // Multiple edge updates:
4111   new_head->set_req(LoopNode::EntryControl,    C->top());  //   use rehash_node_delayed / set_req instead of
4112   new_head->set_req(LoopNode::LoopBackControl, C->top());  //   multiple replace_input_of calls
4113 
4114   // Copy head_clone back-branch info to original head
4115   // and remove original head's loop entry and
4116   // clone head's back-branch
4117   _igvn.rehash_node_delayed(head); // Multiple edge updates
4118   head->set_req(LoopNode::EntryControl,    head_clone->in(LoopNode::LoopBackControl));
4119   head->set_req(LoopNode::LoopBackControl, C->top());
4120   _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
4121 
4122   // Similarly modify the phis
4123   for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
4124     Node* use = head->fast_out(k);
4125     if (use->is_Phi() && use->outcnt() > 0) {
4126       Node* use_clone = old_new[use->_idx];
4127       _igvn.rehash_node_delayed(use); // Multiple edge updates
4128       use->set_req(LoopNode::EntryControl,    use_clone->in(LoopNode::LoopBackControl));
4129       use->set_req(LoopNode::LoopBackControl, C->top());
4130       _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
4131     }
4132   }
4133 
4134   // Step 4: update dominator tree and dominator depth
4135 
4136   set_idom(head, orig_tail_clone, dd);
4137   recompute_dom_depth();
4138 
4139   // Inhibit more partial peeling on this loop
4140   new_head_clone->set_partial_peel_loop();
4141   C->set_major_progress();
4142   loop->record_for_igvn();
4143 
4144 #ifndef PRODUCT
4145   if (TracePartialPeeling) {
4146     tty->print_cr("\nafter partial peel one iteration");
4147     Node_List wl;
4148     Node* t = last_peel;
4149     while (true) {
4150       wl.push(t);
4151       if (t == head_clone) break;
4152       t = idom(t);
4153     }
4154     while (wl.size() > 0) {
4155       Node* tt = wl.pop();
4156       if (tt == head) tty->print_cr("orig head");
4157       else if (tt == new_head_clone) tty->print_cr("new head");
4158       else if (tt == head_clone) tty->print_cr("clone head");
4159       tt->dump();
4160     }
4161   }
4162 #endif
4163 
4164   C->print_method(PHASE_AFTER_PARTIAL_PEELING, 4, new_head_clone);
4165 
4166   return true;
4167 }
4168 
4169 // Transform:
4170 //
4171 // loop<-----------------+
4172 //  |                    |
4173 // stmt1 stmt2 .. stmtn  |
4174 //  |     |        |     |
4175 //  \     |       /      |
4176 //    v   v     v        |
4177 //       region          |
4178 //         |             |
4179 //     shared_stmt       |
4180 //         |             |
4181 //         v             |
4182 //         if            |
4183 //         / \           |
4184 //        |   -----------+
4185 //        v
4186 //
4187 // into:
4188 //
4189 //    loop<-------------------+
4190 //     |                      |
4191 //     v                      |
4192 // +->loop                    |
4193 // |   |                      |
4194 // |  stmt1 stmt2 .. stmtn    |
4195 // |   |     |        |       |
4196 // |   |      \       /       |
4197 // |   |       v     v        |
4198 // |   |        region1       |
4199 // |   |           |          |
4200 // |  shared_stmt shared_stmt |
4201 // |   |           |          |
4202 // |   v           v          |
4203 // |   if          if         |
4204 // |   /\          / \        |
4205 // +--   |         |   -------+
4206 //       \         /
4207 //        v       v
4208 //         region2
4209 //
4210 // (region2 is shown to merge mirrored projections of the loop exit
4211 // ifs to make the diagram clearer but they really merge the same
4212 // projection)
4213 //
4214 // Conditions for this transformation to trigger:
4215 // - the path through stmt1 is frequent enough
4216 // - the inner loop will be turned into a counted loop after transformation
4217 bool PhaseIdealLoop::duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new) {
4218   if (!DuplicateBackedge) {
4219     return false;
4220   }
4221   assert(!loop->_head->is_CountedLoop() || StressDuplicateBackedge, "Non-counted loop only");
4222   if (!loop->_head->is_Loop()) {
4223     return false;
4224   }
4225 
4226   uint estimate = loop->est_loop_clone_sz(1);
4227   if (exceeding_node_budget(estimate)) {
4228     return false;
4229   }
4230 
4231   LoopNode *head = loop->_head->as_Loop();
4232 
4233   Node* region = nullptr;
4234   IfNode* exit_test = nullptr;
4235   uint inner;
4236   float f;
4237   if (StressDuplicateBackedge) {
4238     if (head->is_strip_mined()) {
4239       return false;
4240     }
4241     Node* c = head->in(LoopNode::LoopBackControl);
4242 
4243     while (c != head) {
4244       if (c->is_Region()) {
4245         region = c;
4246       }
4247       c = idom(c);
4248     }
4249 
4250     if (region == nullptr) {
4251       return false;
4252     }
4253 
4254     inner = 1;
4255   } else {
4256     // Is the shape of the loop that of a counted loop...
4257     Node* back_control = loop_exit_control(head, loop);
4258     if (back_control == nullptr) {
4259       return false;
4260     }
4261 
4262     BoolTest::mask bt = BoolTest::illegal;
4263     float cl_prob = 0;
4264     Node* incr = nullptr;
4265     Node* limit = nullptr;
4266     Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob);
4267     if (cmp == nullptr || cmp->Opcode() != Op_CmpI) {
4268       return false;
4269     }
4270 
4271     // With an extra phi for the candidate iv?
4272     // Or the region node is the loop head
4273     if (!incr->is_Phi() || incr->in(0) == head) {
4274       return false;
4275     }
4276 
4277     PathFrequency pf(head, this);
4278     region = incr->in(0);
4279 
4280     // Go over all paths for the extra phi's region and see if that
4281     // path is frequent enough and would match the expected iv shape
4282     // if the extra phi is removed
4283     inner = 0;
4284     for (uint i = 1; i < incr->req(); ++i) {
4285       Node* in = incr->in(i);
4286       Node* trunc1 = nullptr;
4287       Node* trunc2 = nullptr;
4288       const TypeInteger* iv_trunc_t = nullptr;
4289       Node* orig_in = in;
4290       if (!(in = CountedLoopNode::match_incr_with_optional_truncation(in, &trunc1, &trunc2, &iv_trunc_t, T_INT))) {
4291         continue;
4292       }
4293       assert(in->Opcode() == Op_AddI, "wrong increment code");
4294       Node* xphi = nullptr;
4295       Node* stride = loop_iv_stride(in, loop, xphi);
4296 
4297       if (stride == nullptr) {
4298         continue;
4299       }
4300 
4301       PhiNode* phi = loop_iv_phi(xphi, nullptr, head, loop);
4302       if (phi == nullptr ||
4303           (trunc1 == nullptr && phi->in(LoopNode::LoopBackControl) != incr) ||
4304           (trunc1 != nullptr && phi->in(LoopNode::LoopBackControl) != trunc1)) {
4305         return false;
4306       }
4307 
4308       f = pf.to(region->in(i));
4309       if (f > 0.5) {
4310         inner = i;
4311         break;
4312       }
4313     }
4314 
4315     if (inner == 0) {
4316       return false;
4317     }
4318 
4319     exit_test = back_control->in(0)->as_If();
4320   }
4321 
4322   if (idom(region)->is_Catch()) {
4323     return false;
4324   }
4325 
4326   // Collect all control nodes that need to be cloned (shared_stmt in the diagram)
4327   Unique_Node_List wq;
4328   wq.push(head->in(LoopNode::LoopBackControl));
4329   for (uint i = 0; i < wq.size(); i++) {
4330     Node* c = wq.at(i);
4331     assert(get_loop(c) == loop, "not in the right loop?");
4332     if (c->is_Region()) {
4333       if (c != region) {
4334         for (uint j = 1; j < c->req(); ++j) {
4335           wq.push(c->in(j));
4336         }
4337       }
4338     } else {
4339       wq.push(c->in(0));
4340     }
4341     assert(!is_strict_dominator(c, region), "shouldn't go above region");
4342   }
4343 
4344   Node* region_dom = idom(region);
4345 
4346   // Can't do the transformation if this would cause a membar pair to
4347   // be split
4348   for (uint i = 0; i < wq.size(); i++) {
4349     Node* c = wq.at(i);
4350     if (c->is_MemBar() && (c->as_MemBar()->trailing_store() || c->as_MemBar()->trailing_load_store())) {
4351       assert(c->as_MemBar()->leading_membar()->trailing_membar() == c, "bad membar pair");
4352       if (!wq.member(c->as_MemBar()->leading_membar())) {
4353         return false;
4354       }
4355     }
4356   }
4357 
4358   // Collect data nodes that need to be clones as well
4359   int dd = dom_depth(head);
4360 
4361   for (uint i = 0; i < loop->_body.size(); ++i) {
4362     Node* n = loop->_body.at(i);
4363     if (has_ctrl(n)) {
4364       Node* c = get_ctrl(n);
4365       if (wq.member(c)) {
4366         wq.push(n);
4367       }
4368     } else {
4369       set_idom(n, idom(n), dd);
4370     }
4371   }
4372 
4373   // clone shared_stmt
4374   clone_loop_body(wq, old_new, nullptr);
4375 
4376   Node* region_clone = old_new[region->_idx];
4377   region_clone->set_req(inner, C->top());
4378   set_idom(region, region->in(inner), dd);
4379 
4380   // Prepare the outer loop
4381   Node* outer_head = new LoopNode(head->in(LoopNode::EntryControl), old_new[head->in(LoopNode::LoopBackControl)->_idx]);
4382   register_control(outer_head, loop->_parent, outer_head->in(LoopNode::EntryControl));
4383   _igvn.replace_input_of(head, LoopNode::EntryControl, outer_head);
4384   set_idom(head, outer_head, dd);
4385 
4386   fix_body_edges(wq, loop, old_new, dd, loop->_parent, true);
4387 
4388   // Make one of the shared_stmt copies only reachable from stmt1, the
4389   // other only from stmt2..stmtn.
4390   Node* dom = nullptr;
4391   for (uint i = 1; i < region->req(); ++i) {
4392     if (i != inner) {
4393       _igvn.replace_input_of(region, i, C->top());
4394     }
4395     Node* in = region_clone->in(i);
4396     if (in->is_top()) {
4397       continue;
4398     }
4399     if (dom == nullptr) {
4400       dom = in;
4401     } else {
4402       dom = dom_lca(dom, in);
4403     }
4404   }
4405 
4406   set_idom(region_clone, dom, dd);
4407 
4408   // Set up the outer loop
4409   for (uint i = 0; i < head->outcnt(); i++) {
4410     Node* u = head->raw_out(i);
4411     if (u->is_Phi()) {
4412       Node* outer_phi = u->clone();
4413       outer_phi->set_req(0, outer_head);
4414       Node* backedge = old_new[u->in(LoopNode::LoopBackControl)->_idx];
4415       if (backedge == nullptr) {
4416         backedge = u->in(LoopNode::LoopBackControl);
4417       }
4418       outer_phi->set_req(LoopNode::LoopBackControl, backedge);
4419       register_new_node(outer_phi, outer_head);
4420       _igvn.replace_input_of(u, LoopNode::EntryControl, outer_phi);
4421     }
4422   }
4423 
4424   // create control and data nodes for out of loop uses (including region2)
4425   Node_List worklist;
4426   uint new_counter = C->unique();
4427   fix_ctrl_uses(wq, loop, old_new, ControlAroundStripMined, outer_head, nullptr, worklist);
4428 
4429   Node_List *split_if_set = nullptr;
4430   Node_List *split_bool_set = nullptr;
4431   Node_List *split_cex_set = nullptr;
4432   fix_data_uses(wq, loop, ControlAroundStripMined, loop->skip_strip_mined(), new_counter, old_new, worklist,
4433                 split_if_set, split_bool_set, split_cex_set);
4434 
4435   finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
4436 
4437   if (exit_test != nullptr) {
4438     float cnt = exit_test->_fcnt;
4439     if (cnt != COUNT_UNKNOWN) {
4440       exit_test->_fcnt = cnt * f;
4441       old_new[exit_test->_idx]->as_If()->_fcnt = cnt * (1 - f);
4442     }
4443   }
4444 
4445   C->set_major_progress();
4446 
4447   return true;
4448 }
4449 
4450 // AutoVectorize the loop: replace scalar ops with vector ops.
4451 PhaseIdealLoop::AutoVectorizeStatus
4452 PhaseIdealLoop::auto_vectorize(IdealLoopTree* lpt, VSharedData &vshared) {
4453   // Counted loop only
4454   if (!lpt->is_counted()) {
4455     return AutoVectorizeStatus::Impossible;
4456   }
4457 
4458   // Main-loop only
4459   CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4460   if (!cl->is_main_loop()) {
4461     return AutoVectorizeStatus::Impossible;
4462   }
4463 
4464   VLoop vloop(lpt, false);
4465   if (!vloop.check_preconditions()) {
4466     return AutoVectorizeStatus::TriedAndFailed;
4467   }
4468 
4469   // Ensure the shared data is cleared before each use
4470   vshared.clear();
4471 
4472   const VLoopAnalyzer vloop_analyzer(vloop, vshared);
4473   if (!vloop_analyzer.success()) {
4474     return AutoVectorizeStatus::TriedAndFailed;
4475   }
4476 
4477   SuperWord sw(vloop_analyzer);
4478   if (!sw.transform_loop()) {
4479     return AutoVectorizeStatus::TriedAndFailed;
4480   }
4481 
4482   return AutoVectorizeStatus::Success;
4483 }
4484 
4485 // Just before insert_pre_post_loops, we can multi-version the loop:
4486 //
4487 //              multiversion_if
4488 //               |       |
4489 //         fast_loop   slow_loop
4490 //
4491 // In the fast_loop we can make speculative assumptions, and put the
4492 // conditions into the multiversion_if. If the conditions hold at runtime,
4493 // we enter the fast_loop, if the conditions fail, we take the slow_loop
4494 // instead which does not make any of the speculative assumptions.
4495 //
4496 // Note: we only multiversion the loop if the loop does not have any
4497 //       auto vectorization check Predicate. If we have that predicate,
4498 //       then we can simply add the speculative assumption checks to
4499 //       that Predicate. This means we do not need to duplicate the
4500 //       loop - we have a smaller graph and save compile time. Should
4501 //       the conditions ever fail, then we deopt / trap at the Predicate
4502 //       and recompile without that Predicate. At that point we will
4503 //       multiversion the loop, so that we can still have speculative
4504 //       runtime checks.
4505 //
4506 // We perform the multiversioning when the loop is still in its single
4507 // iteration form, even before we insert pre and post loops. This makes
4508 // the cloning much simpler. However, this means that both the fast
4509 // and the slow loop have to be optimized independently (adding pre
4510 // and post loops, unrolling the main loop, auto-vectorize etc.). And
4511 // we may end up not needing any speculative assumptions in the fast_loop
4512 // and then rejecting the slow_loop by constant folding the multiversion_if.
4513 //
4514 // Therefore, we "delay" the optimization of the slow_loop until we add
4515 // at least one speculative assumption for the fast_loop. If we never
4516 // add such a speculative runtime check, the OpaqueMultiversioningNode
4517 // of the multiversion_if constant folds to true after loop opts, and the
4518 // multiversion_if folds away the "delayed" slow_loop. If we add any
4519 // speculative assumption, then we notify the OpaqueMultiversioningNode
4520 // with "notify_slow_loop_that_it_can_resume_optimizations".
4521 //
4522 // Note: new runtime checks can be added to the multiversion_if with
4523 //       PhaseIdealLoop::create_new_if_for_multiversion
4524 void PhaseIdealLoop::maybe_multiversion_for_auto_vectorization_runtime_checks(IdealLoopTree* lpt, Node_List& old_new) {
4525   CountedLoopNode* cl = lpt->_head->as_CountedLoop();
4526   LoopNode* outer_loop = cl->skip_strip_mined();
4527   Node* entry = outer_loop->in(LoopNode::EntryControl);
4528 
4529   // Check we have multiversioning enabled, and are not already multiversioned.
4530   if (!LoopMultiversioning || cl->is_multiversion()) { return; }
4531 
4532   // Check that we do not have a parse-predicate where we can add the runtime checks
4533   // during auto-vectorization.
4534   const Predicates predicates(entry);
4535   const PredicateBlock* predicate_block = predicates.auto_vectorization_check_block();
4536   if (predicate_block->has_parse_predicate()) { return; }
4537 
4538   // Check node budget.
4539   uint estimate = lpt->est_loop_clone_sz(2);
4540   if (!may_require_nodes(estimate)) { return; }
4541 
4542   do_multiversioning(lpt, old_new);
4543 }
4544 
4545 // Returns true if the Reduction node is unordered.
4546 static bool is_unordered_reduction(Node* n) {
4547   return n->is_Reduction() && !n->as_Reduction()->requires_strict_order();
4548 }
4549 
4550 // Having ReductionNodes in the loop is expensive. They need to recursively
4551 // fold together the vector values, for every vectorized loop iteration. If
4552 // we encounter the following pattern, we can vector accumulate the values
4553 // inside the loop, and only have a single UnorderedReduction after the loop.
4554 //
4555 // Note: UnorderedReduction represents a ReductionNode which does not require
4556 // calculating in strict order.
4557 //
4558 // CountedLoop     init
4559 //          |        |
4560 //          +------+ | +-----------------------+
4561 //                 | | |                       |
4562 //                PhiNode (s)                  |
4563 //                  |                          |
4564 //                  |          Vector          |
4565 //                  |            |             |
4566 //               UnorderedReduction (first_ur) |
4567 //                  |                          |
4568 //                 ...         Vector          |
4569 //                  |            |             |
4570 //               UnorderedReduction (last_ur)  |
4571 //                       |                     |
4572 //                       +---------------------+
4573 //
4574 // We patch the graph to look like this:
4575 //
4576 // CountedLoop   identity_vector
4577 //         |         |
4578 //         +-------+ | +---------------+
4579 //                 | | |               |
4580 //                PhiNode (v)          |
4581 //                   |                 |
4582 //                   |         Vector  |
4583 //                   |           |     |
4584 //                 VectorAccumulator   |
4585 //                   |                 |
4586 //                  ...        Vector  |
4587 //                   |           |     |
4588 //      init       VectorAccumulator   |
4589 //        |          |     |           |
4590 //     UnorderedReduction  +-----------+
4591 //
4592 // We turned the scalar (s) Phi into a vectorized one (v). In the loop, we
4593 // use vector_accumulators, which do the same reductions, but only element
4594 // wise. This is a single operation per vector_accumulator, rather than many
4595 // for a UnorderedReduction. We can then reduce the last vector_accumulator
4596 // after the loop, and also reduce the init value into it.
4597 //
4598 // We can not do this with all reductions. Some reductions do not allow the
4599 // reordering of operations (for example float addition/multiplication require
4600 // strict order).
4601 void PhaseIdealLoop::move_unordered_reduction_out_of_loop(IdealLoopTree* loop) {
4602   assert(!C->major_progress() && loop->is_counted() && loop->is_innermost(), "sanity");
4603 
4604   // Find all Phi nodes with an unordered Reduction on backedge.
4605   CountedLoopNode* cl = loop->_head->as_CountedLoop();
4606   for (DUIterator_Fast jmax, j = cl->fast_outs(jmax); j < jmax; j++) {
4607     Node* phi = cl->fast_out(j);
4608     // We have a phi with a single use, and an unordered Reduction on the backedge.
4609     if (!phi->is_Phi() || phi->outcnt() != 1 || !is_unordered_reduction(phi->in(2))) {
4610       continue;
4611     }
4612 
4613     ReductionNode* last_ur = phi->in(2)->as_Reduction();
4614     assert(!last_ur->requires_strict_order(), "must be");
4615 
4616     // Determine types
4617     const TypeVect* vec_t = last_ur->vect_type();
4618     uint vector_length    = vec_t->length();
4619     BasicType bt          = vec_t->element_basic_type();
4620 
4621     // Convert opcode from vector-reduction -> scalar -> normal-vector-op
4622     const int sopc        = VectorNode::scalar_opcode(last_ur->Opcode(), bt);
4623     const int vopc        = VectorNode::opcode(sopc, bt);
4624     if (!Matcher::match_rule_supported_vector(vopc, vector_length, bt)) {
4625         DEBUG_ONLY( last_ur->dump(); )
4626         assert(false, "do not have normal vector op for this reduction");
4627         continue; // not implemented -> fails
4628     }
4629 
4630     // Traverse up the chain of unordered Reductions, checking that it loops back to
4631     // the phi. Check that all unordered Reductions only have a single use, except for
4632     // the last (last_ur), which only has phi as a use in the loop, and all other uses
4633     // are outside the loop.
4634     ReductionNode* current = last_ur;
4635     ReductionNode* first_ur = nullptr;
4636     while (true) {
4637       assert(!current->requires_strict_order(), "sanity");
4638 
4639       // Expect no ctrl and a vector_input from within the loop.
4640       Node* ctrl = current->in(0);
4641       Node* vector_input = current->in(2);
4642       if (ctrl != nullptr || get_ctrl(vector_input) != cl) {
4643         DEBUG_ONLY( current->dump(1); )
4644         assert(false, "reduction has ctrl or bad vector_input");
4645         break; // Chain traversal fails.
4646       }
4647 
4648       assert(current->vect_type() != nullptr, "must have vector type");
4649       if (current->vect_type() != last_ur->vect_type()) {
4650         // Reductions do not have the same vector type (length and element type).
4651         break; // Chain traversal fails.
4652       }
4653 
4654       // Expect single use of an unordered Reduction, except for last_ur.
4655       if (current == last_ur) {
4656         // Expect all uses to be outside the loop, except phi.
4657         for (DUIterator_Fast kmax, k = current->fast_outs(kmax); k < kmax; k++) {
4658           Node* use = current->fast_out(k);
4659           if (use != phi && ctrl_or_self(use) == cl) {
4660             DEBUG_ONLY( current->dump(-1); )
4661             assert(false, "reduction has use inside loop");
4662             // Should not be allowed by SuperWord::mark_reductions
4663             return; // bail out of optimization
4664           }
4665         }
4666       } else {
4667         if (current->outcnt() != 1) {
4668           break; // Chain traversal fails.
4669         }
4670       }
4671 
4672       // Expect another unordered Reduction or phi as the scalar input.
4673       Node* scalar_input = current->in(1);
4674       if (is_unordered_reduction(scalar_input) &&
4675           scalar_input->Opcode() == current->Opcode()) {
4676         // Move up the unordered Reduction chain.
4677         current = scalar_input->as_Reduction();
4678         assert(!current->requires_strict_order(), "must be");
4679       } else if (scalar_input == phi) {
4680         // Chain terminates at phi.
4681         first_ur = current;
4682         current = nullptr;
4683         break; // Success.
4684       } else {
4685         // scalar_input is neither phi nor a matching reduction
4686         // Can for example be scalar reduction when we have
4687         // partial vectorization.
4688         break; // Chain traversal fails.
4689       }
4690     }
4691     if (current != nullptr) {
4692       // Chain traversal was not successful.
4693       continue;
4694     }
4695     assert(first_ur != nullptr, "must have successfully terminated chain traversal");
4696 
4697     Node* identity_scalar = ReductionNode::make_identity_con_scalar(_igvn, sopc, bt);
4698     set_root_as_ctrl(identity_scalar);
4699     VectorNode* identity_vector = VectorNode::scalar2vector(identity_scalar, vector_length, bt);
4700     register_new_node(identity_vector, C->root());
4701     assert(vec_t == identity_vector->vect_type(), "matching vector type");
4702     VectorNode::trace_new_vector(identity_vector, "Unordered Reduction");
4703 
4704     // Turn the scalar phi into a vector phi.
4705     _igvn.rehash_node_delayed(phi);
4706     Node* init = phi->in(1); // Remember init before replacing it.
4707     phi->set_req_X(1, identity_vector, &_igvn);
4708     phi->as_Type()->set_type(vec_t);
4709     _igvn.set_type(phi, vec_t);
4710 
4711     // Traverse down the chain of unordered Reductions, and replace them with vector_accumulators.
4712     current = first_ur;
4713     while (true) {
4714       // Create vector_accumulator to replace current.
4715       Node* last_vector_accumulator = current->in(1);
4716       Node* vector_input            = current->in(2);
4717       VectorNode* vector_accumulator = VectorNode::make(vopc, last_vector_accumulator, vector_input, vec_t);
4718       register_new_node(vector_accumulator, cl);
4719       _igvn.replace_node(current, vector_accumulator);
4720       VectorNode::trace_new_vector(vector_accumulator, "Unordered Reduction");
4721       if (current == last_ur) {
4722         break;
4723       }
4724       current = vector_accumulator->unique_out()->as_Reduction();
4725       assert(!current->requires_strict_order(), "must be");
4726     }
4727 
4728     // Create post-loop reduction.
4729     Node* last_accumulator = phi->in(2);
4730     Node* post_loop_reduction = ReductionNode::make(sopc, nullptr, init, last_accumulator, bt);
4731 
4732     // Take over uses of last_accumulator that are not in the loop.
4733     for (DUIterator i = last_accumulator->outs(); last_accumulator->has_out(i); i++) {
4734       Node* use = last_accumulator->out(i);
4735       if (use != phi && use != post_loop_reduction) {
4736         assert(ctrl_or_self(use) != cl, "use must be outside loop");
4737         use->replace_edge(last_accumulator, post_loop_reduction,  &_igvn);
4738         --i;
4739       }
4740     }
4741     register_new_node(post_loop_reduction, get_late_ctrl(post_loop_reduction, cl));
4742     VectorNode::trace_new_vector(post_loop_reduction, "Unordered Reduction");
4743 
4744     assert(last_accumulator->outcnt() == 2, "last_accumulator has 2 uses: phi and post_loop_reduction");
4745     assert(post_loop_reduction->outcnt() > 0, "should have taken over all non loop uses of last_accumulator");
4746     assert(phi->outcnt() == 1, "accumulator is the only use of phi");
4747   }
4748 }
4749 
4750 void DataNodeGraph::clone_data_nodes(Node* new_ctrl) {
4751   for (uint i = 0; i < _data_nodes.size(); i++) {
4752     clone(_data_nodes[i], new_ctrl);
4753   }
4754 }
4755 
4756 // Clone the given node and set it up properly. Set 'new_ctrl' as ctrl.
4757 void DataNodeGraph::clone(Node* node, Node* new_ctrl) {
4758   Node* clone = node->clone();
4759   _phase->igvn().register_new_node_with_optimizer(clone);
4760   _orig_to_new.put(node, clone);
4761   _phase->set_ctrl(clone, new_ctrl);
4762   if (node->is_CastII()) {
4763     clone->set_req(0, new_ctrl);
4764   }
4765 }
4766 
4767 // Rewire the data inputs of all (unprocessed) cloned nodes, whose inputs are still pointing to the same inputs as their
4768 // corresponding orig nodes, to the newly cloned inputs to create a separate cloned graph.
4769 void DataNodeGraph::rewire_clones_to_cloned_inputs() {
4770   _orig_to_new.iterate_all([&](Node* node, Node* clone) {
4771     for (uint i = 1; i < node->req(); i++) {
4772       Node** cloned_input = _orig_to_new.get(node->in(i));
4773       if (cloned_input != nullptr) {
4774         // Input was also cloned -> rewire clone to the cloned input.
4775         _phase->igvn().replace_input_of(clone, i, *cloned_input);
4776       }
4777     }
4778   });
4779 }
4780 
4781 // Clone all non-OpaqueLoop* nodes and apply the provided transformation strategy for OpaqueLoop* nodes.
4782 // Set 'new_ctrl' as ctrl for all cloned non-OpaqueLoop* nodes.
4783 void DataNodeGraph::clone_data_nodes_and_transform_opaque_loop_nodes(
4784     const TransformStrategyForOpaqueLoopNodes& transform_strategy,
4785     Node* new_ctrl) {
4786   for (uint i = 0; i < _data_nodes.size(); i++) {
4787     Node* data_node = _data_nodes[i];
4788     if (data_node->is_Opaque1()) {
4789       transform_opaque_node(transform_strategy, data_node);
4790     } else {
4791       clone(data_node, new_ctrl);
4792     }
4793   }
4794 }
4795 
4796 void DataNodeGraph::transform_opaque_node(const TransformStrategyForOpaqueLoopNodes& transform_strategy, Node* node) {
4797   Node* transformed_node;
4798   if (node->is_OpaqueLoopInit()) {
4799     transformed_node = transform_strategy.transform_opaque_init(node->as_OpaqueLoopInit());
4800   } else {
4801     assert(node->is_OpaqueLoopStride(), "must be OpaqueLoopStrideNode");
4802     transformed_node = transform_strategy.transform_opaque_stride(node->as_OpaqueLoopStride());
4803   }
4804   // Add an orig->new mapping to correctly update the inputs of the copied graph in rewire_clones_to_cloned_inputs().
4805   _orig_to_new.put(node, transformed_node);
4806 }