1 /*
   2  * Copyright (c) 1999, 2023, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/barrierSet.hpp"
  27 #include "gc/shared/c2/barrierSetC2.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "memory/resourceArea.hpp"
  30 #include "opto/addnode.hpp"
  31 #include "opto/callnode.hpp"
  32 #include "opto/castnode.hpp"
  33 #include "opto/connode.hpp"
  34 #include "opto/castnode.hpp"
  35 #include "opto/divnode.hpp"
  36 #include "opto/inlinetypenode.hpp"
  37 #include "opto/loopnode.hpp"
  38 #include "opto/matcher.hpp"
  39 #include "opto/mulnode.hpp"
  40 #include "opto/movenode.hpp"
  41 #include "opto/opaquenode.hpp"
  42 #include "opto/rootnode.hpp"
  43 #include "opto/subnode.hpp"
  44 #include "opto/subtypenode.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     // ConvI2L may have type information on it which is unsafe to push up
  53     // so disable this for now
  54     return NULL;
  55   }
  56 
  57   // Splitting range check CastIIs through a loop induction Phi can
  58   // cause new Phis to be created that are left unrelated to the loop
  59   // induction Phi and prevent optimizations (vectorization)
  60   if (n->Opcode() == Op_CastII && region->is_CountedLoop() &&
  61       n->in(1) == region->as_CountedLoop()->phi()) {
  62     return NULL;
  63   }
  64 
  65   // Inline types should not be split through Phis because they cannot be merged
  66   // through Phi nodes but each value input needs to be merged individually.
  67   if (n->is_InlineType()) {
  68     return NULL;
  69   }
  70 
  71   if (cannot_split_division(n, region)) {
  72     return NULL;
  73   }
  74 
  75   int wins = 0;
  76   assert(!n->is_CFG(), "");
  77   assert(region->is_Region(), "");
  78 
  79   const Type* type = n->bottom_type();
  80   const TypeOopPtr* t_oop = _igvn.type(n)->isa_oopptr();
  81   Node* phi;
  82   if (t_oop != NULL && t_oop->is_known_instance_field()) {
  83     int iid    = t_oop->instance_id();
  84     int index  = C->get_alias_index(t_oop);
  85     int offset = t_oop->offset();
  86     phi = new PhiNode(region, type, NULL, iid, index, offset);
  87   } else {
  88     phi = PhiNode::make_blank(region, n);
  89   }
  90   uint old_unique = C->unique();
  91   for (uint i = 1; i < region->req(); i++) {
  92     Node* x;
  93     Node* the_clone = NULL;
  94     if (region->in(i) == C->top()) {
  95       x = C->top();             // Dead path?  Use a dead data op
  96     } else {
  97       x = n->clone();           // Else clone up the data op
  98       the_clone = x;            // Remember for possible deletion.
  99       // Alter data node to use pre-phi inputs
 100       if (n->in(0) == region)
 101         x->set_req( 0, region->in(i) );
 102       for (uint j = 1; j < n->req(); j++) {
 103         Node* in = n->in(j);
 104         if (in->is_Phi() && in->in(0) == region)
 105           x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
 106       }
 107     }
 108     // Check for a 'win' on some paths
 109     const Type* t = x->Value(&_igvn);
 110 
 111     bool singleton = t->singleton();
 112 
 113     // A TOP singleton indicates that there are no possible values incoming
 114     // along a particular edge. In most cases, this is OK, and the Phi will
 115     // be eliminated later in an Ideal call. However, we can't allow this to
 116     // happen if the singleton occurs on loop entry, as the elimination of
 117     // the PhiNode may cause the resulting node to migrate back to a previous
 118     // loop iteration.
 119     if (singleton && t == Type::TOP) {
 120       // Is_Loop() == false does not confirm the absence of a loop (e.g., an
 121       // irreducible loop may not be indicated by an affirmative is_Loop());
 122       // therefore, the only top we can split thru a phi is on a backedge of
 123       // a loop.
 124       singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
 125     }
 126 
 127     if (singleton) {
 128       wins++;
 129       x = ((PhaseGVN&)_igvn).makecon(t);
 130     } else {
 131       // We now call Identity to try to simplify the cloned node.
 132       // Note that some Identity methods call phase->type(this).
 133       // Make sure that the type array is big enough for
 134       // our new node, even though we may throw the node away.
 135       // (Note: This tweaking with igvn only works because x is a new node.)
 136       _igvn.set_type(x, t);
 137       // If x is a TypeNode, capture any more-precise type permanently into Node
 138       // otherwise it will be not updated during igvn->transform since
 139       // igvn->type(x) is set to x->Value() already.
 140       x->raise_bottom_type(t);
 141       Node* y = x->Identity(&_igvn);
 142       if (y != x) {
 143         wins++;
 144         x = y;
 145       } else {
 146         y = _igvn.hash_find(x);
 147         if (y) {
 148           wins++;
 149           x = y;
 150         } else {
 151           // Else x is a new node we are keeping
 152           // We do not need register_new_node_with_optimizer
 153           // because set_type has already been called.
 154           _igvn._worklist.push(x);
 155         }
 156       }
 157     }
 158     if (x != the_clone && the_clone != NULL)
 159       _igvn.remove_dead_node(the_clone);
 160     phi->set_req( i, x );
 161   }
 162   // Too few wins?
 163   if (wins <= policy) {
 164     _igvn.remove_dead_node(phi);
 165     return NULL;
 166   }
 167 
 168   // Record Phi
 169   register_new_node( phi, region );
 170 
 171   for (uint i2 = 1; i2 < phi->req(); i2++) {
 172     Node *x = phi->in(i2);
 173     // If we commoned up the cloned 'x' with another existing Node,
 174     // the existing Node picks up a new use.  We need to make the
 175     // existing Node occur higher up so it dominates its uses.
 176     Node *old_ctrl;
 177     IdealLoopTree *old_loop;
 178 
 179     if (x->is_Con()) {
 180       // Constant's control is always root.
 181       set_ctrl(x, C->root());
 182       continue;
 183     }
 184     // The occasional new node
 185     if (x->_idx >= old_unique) {     // Found a new, unplaced node?
 186       old_ctrl = NULL;
 187       old_loop = NULL;               // Not in any prior loop
 188     } else {
 189       old_ctrl = get_ctrl(x);
 190       old_loop = get_loop(old_ctrl); // Get prior loop
 191     }
 192     // New late point must dominate new use
 193     Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
 194     if (new_ctrl == old_ctrl) // Nothing is changed
 195       continue;
 196 
 197     IdealLoopTree *new_loop = get_loop(new_ctrl);
 198 
 199     // Don't move x into a loop if its uses are
 200     // outside of loop. Otherwise x will be cloned
 201     // for each use outside of this loop.
 202     IdealLoopTree *use_loop = get_loop(region);
 203     if (!new_loop->is_member(use_loop) &&
 204         (old_loop == NULL || !new_loop->is_member(old_loop))) {
 205       // Take early control, later control will be recalculated
 206       // during next iteration of loop optimizations.
 207       new_ctrl = get_early_ctrl(x);
 208       new_loop = get_loop(new_ctrl);
 209     }
 210     // Set new location
 211     set_ctrl(x, new_ctrl);
 212     // If changing loop bodies, see if we need to collect into new body
 213     if (old_loop != new_loop) {
 214       if (old_loop && !old_loop->_child)
 215         old_loop->_body.yank(x);
 216       if (!new_loop->_child)
 217         new_loop->_body.push(x);  // Collect body info
 218     }
 219   }
 220 
 221   return phi;
 222 }
 223 
 224 // Return true if 'n' is a Div or Mod node (without zero check If node which was removed earlier) with a loop phi divisor
 225 // of a trip-counted (integer or long) loop with a backedge input that could be zero (include zero in its type range). In
 226 // this case, we cannot split the division to the backedge as it could freely float above the loop exit check resulting in
 227 // a division by zero. This situation is possible because the type of an increment node of an iv phi (trip-counter) could
 228 // include zero while the iv phi does not (see PhiNode::Value() for trip-counted loops where we improve types of iv phis).
 229 // We also need to check other loop phis as they could have been created in the same split-if pass when applying
 230 // PhaseIdealLoop::split_thru_phi() to split nodes through an iv phi.
 231 bool PhaseIdealLoop::cannot_split_division(const Node* n, const Node* region) const {
 232   const Type* zero;
 233   switch (n->Opcode()) {
 234     case Op_DivI:
 235     case Op_ModI:
 236       zero = TypeInt::ZERO;
 237       break;
 238     case Op_DivL:
 239     case Op_ModL:
 240       zero = TypeLong::ZERO;
 241       break;
 242     default:
 243       return false;
 244   }
 245 
 246   assert(n->in(0) == NULL, "divisions with zero check should already have bailed out earlier in split-if");
 247   Node* divisor = n->in(2);
 248   return is_divisor_counted_loop_phi(divisor, region) &&
 249          loop_phi_backedge_type_contains_zero(divisor, zero);
 250 }
 251 
 252 bool PhaseIdealLoop::is_divisor_counted_loop_phi(const Node* divisor, const Node* loop) {
 253   return loop->is_BaseCountedLoop() && divisor->is_Phi() && divisor->in(0) == loop;
 254 }
 255 
 256 bool PhaseIdealLoop::loop_phi_backedge_type_contains_zero(const Node* phi_divisor, const Type* zero) const {
 257     return _igvn.type(phi_divisor->in(LoopNode::LoopBackControl))->filter_speculative(zero) != Type::TOP;
 258 }
 259 
 260 //------------------------------dominated_by------------------------------------
 261 // Replace the dominated test with an obvious true or false.  Place it on the
 262 // IGVN worklist for later cleanup.  Move control-dependent data Nodes on the
 263 // live path up to the dominating control.
 264 void PhaseIdealLoop::dominated_by(IfProjNode* prevdom, IfNode* iff, bool flip, bool exclude_loop_predicate) {
 265   if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
 266 
 267   // prevdom is the dominating projection of the dominating test.
 268   assert(iff->Opcode() == Op_If ||
 269          iff->Opcode() == Op_CountedLoopEnd ||
 270          iff->Opcode() == Op_LongCountedLoopEnd ||
 271          iff->Opcode() == Op_RangeCheck,
 272         "Check this code when new subtype is added");
 273 
 274   int pop = prevdom->Opcode();
 275   assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
 276   if (flip) {
 277     if (pop == Op_IfTrue)
 278       pop = Op_IfFalse;
 279     else
 280       pop = Op_IfTrue;
 281   }
 282   // 'con' is set to true or false to kill the dominated test.
 283   Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
 284   set_ctrl(con, C->root()); // Constant gets a new use
 285   // Hack the dominated test
 286   _igvn.replace_input_of(iff, 1, con);
 287 
 288   // If I dont have a reachable TRUE and FALSE path following the IfNode then
 289   // I can assume this path reaches an infinite loop.  In this case it's not
 290   // important to optimize the data Nodes - either the whole compilation will
 291   // be tossed or this path (and all data Nodes) will go dead.
 292   if (iff->outcnt() != 2) return;
 293 
 294   // Make control-dependent data Nodes on the live path (path that will remain
 295   // once the dominated IF is removed) become control-dependent on the
 296   // dominating projection.
 297   Node* dp = iff->proj_out_or_null(pop == Op_IfTrue);
 298 
 299   // Loop predicates may have depending checks which should not
 300   // be skipped. For example, range check predicate has two checks
 301   // for lower and upper bounds.
 302   if (dp == NULL)
 303     return;
 304 
 305   ProjNode* dp_proj  = dp->as_Proj();
 306   ProjNode* unc_proj = iff->proj_out(1 - dp_proj->_con)->as_Proj();
 307   if (exclude_loop_predicate &&
 308       (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
 309        unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != NULL ||
 310        unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
 311     // If this is a range check (IfNode::is_range_check), do not
 312     // reorder because Compile::allow_range_check_smearing might have
 313     // changed the check.
 314     return; // Let IGVN transformation change control dependence.
 315   }
 316 
 317   IdealLoopTree* old_loop = get_loop(dp);
 318 
 319   for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
 320     Node* cd = dp->fast_out(i); // Control-dependent node
 321     // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
 322     if (cd->depends_only_on_test() && _igvn.no_dependent_zero_check(cd)) {
 323       assert(cd->in(0) == dp, "");
 324       _igvn.replace_input_of(cd, 0, prevdom);
 325       set_early_ctrl(cd, false);
 326       IdealLoopTree* new_loop = get_loop(get_ctrl(cd));
 327       if (old_loop != new_loop) {
 328         if (!old_loop->_child) {
 329           old_loop->_body.yank(cd);
 330         }
 331         if (!new_loop->_child) {
 332           new_loop->_body.push(cd);
 333         }
 334       }
 335       --i;
 336       --imax;
 337     }
 338   }
 339 }
 340 
 341 //------------------------------has_local_phi_input----------------------------
 342 // Return TRUE if 'n' has Phi inputs from its local block and no other
 343 // block-local inputs (all non-local-phi inputs come from earlier blocks)
 344 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
 345   Node *n_ctrl = get_ctrl(n);
 346   // See if some inputs come from a Phi in this block, or from before
 347   // this block.
 348   uint i;
 349   for( i = 1; i < n->req(); i++ ) {
 350     Node *phi = n->in(i);
 351     if( phi->is_Phi() && phi->in(0) == n_ctrl )
 352       break;
 353   }
 354   if( i >= n->req() )
 355     return NULL;                // No Phi inputs; nowhere to clone thru
 356 
 357   // Check for inputs created between 'n' and the Phi input.  These
 358   // must split as well; they have already been given the chance
 359   // (courtesy of a post-order visit) and since they did not we must
 360   // recover the 'cost' of splitting them by being very profitable
 361   // when splitting 'n'.  Since this is unlikely we simply give up.
 362   for( i = 1; i < n->req(); i++ ) {
 363     Node *m = n->in(i);
 364     if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
 365       // We allow the special case of AddP's with no local inputs.
 366       // This allows us to split-up address expressions.
 367       if (m->is_AddP() &&
 368           get_ctrl(m->in(AddPNode::Base)) != n_ctrl &&
 369           get_ctrl(m->in(AddPNode::Address)) != n_ctrl &&
 370           get_ctrl(m->in(AddPNode::Offset)) != n_ctrl) {
 371         // Move the AddP up to the dominating point. That's fine because control of m's inputs
 372         // must dominate get_ctrl(m) == n_ctrl and we just checked that the input controls are != n_ctrl.
 373         Node* c = find_non_split_ctrl(idom(n_ctrl));
 374         if (c->is_OuterStripMinedLoop()) {
 375           c->as_Loop()->verify_strip_mined(1);
 376           c = c->in(LoopNode::EntryControl);
 377         }
 378         set_ctrl_and_loop(m, c);
 379         continue;
 380       }
 381       return NULL;
 382     }
 383     assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
 384   }
 385 
 386   return n_ctrl;
 387 }
 388 
 389 // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
 390 Node* PhaseIdealLoop::remix_address_expressions_add_left_shift(Node* n, IdealLoopTree* n_loop, Node* n_ctrl, BasicType bt) {
 391   assert(bt == T_INT || bt == T_LONG, "only for integers");
 392   int n_op = n->Opcode();
 393 
 394   if (n_op == Op_LShift(bt)) {
 395     // Scale is loop invariant
 396     Node* scale = n->in(2);
 397     Node* scale_ctrl = get_ctrl(scale);
 398     IdealLoopTree* scale_loop = get_loop(scale_ctrl);
 399     if (n_loop == scale_loop || !scale_loop->is_member(n_loop)) {
 400       return NULL;
 401     }
 402     const TypeInt* scale_t = scale->bottom_type()->isa_int();
 403     if (scale_t != NULL && scale_t->is_con() && scale_t->get_con() >= 16) {
 404       return NULL;              // Dont bother with byte/short masking
 405     }
 406     // Add must vary with loop (else shift would be loop-invariant)
 407     Node* add = n->in(1);
 408     Node* add_ctrl = get_ctrl(add);
 409     IdealLoopTree* add_loop = get_loop(add_ctrl);
 410     if (n_loop != add_loop) {
 411       return NULL;  // happens w/ evil ZKM loops
 412     }
 413 
 414     // Convert I-V into I+ (0-V); same for V-I
 415     if (add->Opcode() == Op_Sub(bt) &&
 416         _igvn.type(add->in(1)) != TypeInteger::zero(bt)) {
 417       assert(add->Opcode() == Op_SubI || add->Opcode() == Op_SubL, "");
 418       Node* zero = _igvn.integercon(0, bt);
 419       set_ctrl(zero, C->root());
 420       Node* neg = SubNode::make(zero, add->in(2), bt);
 421       register_new_node(neg, get_ctrl(add->in(2)));
 422       add = AddNode::make(add->in(1), neg, bt);
 423       register_new_node(add, add_ctrl);
 424     }
 425     if (add->Opcode() != Op_Add(bt)) return NULL;
 426     assert(add->Opcode() == Op_AddI || add->Opcode() == Op_AddL, "");
 427     // See if one add input is loop invariant
 428     Node* add_var = add->in(1);
 429     Node* add_var_ctrl = get_ctrl(add_var);
 430     IdealLoopTree* add_var_loop = get_loop(add_var_ctrl);
 431     Node* add_invar = add->in(2);
 432     Node* add_invar_ctrl = get_ctrl(add_invar);
 433     IdealLoopTree* add_invar_loop = get_loop(add_invar_ctrl);
 434     if (add_invar_loop == n_loop) {
 435       // Swap to find the invariant part
 436       add_invar = add_var;
 437       add_invar_ctrl = add_var_ctrl;
 438       add_invar_loop = add_var_loop;
 439       add_var = add->in(2);
 440     } else if (add_var_loop != n_loop) { // Else neither input is loop invariant
 441       return NULL;
 442     }
 443     if (n_loop == add_invar_loop || !add_invar_loop->is_member(n_loop)) {
 444       return NULL;              // No invariant part of the add?
 445     }
 446 
 447     // Yes!  Reshape address expression!
 448     Node* inv_scale = LShiftNode::make(add_invar, scale, bt);
 449     Node* inv_scale_ctrl =
 450             dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
 451             add_invar_ctrl : scale_ctrl;
 452     register_new_node(inv_scale, inv_scale_ctrl);
 453     Node* var_scale = LShiftNode::make(add_var, scale, bt);
 454     register_new_node(var_scale, n_ctrl);
 455     Node* var_add = AddNode::make(var_scale, inv_scale, bt);
 456     register_new_node(var_add, n_ctrl);
 457     _igvn.replace_node(n, var_add);
 458     return var_add;
 459   }
 460   return NULL;
 461 }
 462 
 463 //------------------------------remix_address_expressions----------------------
 464 // Rework addressing expressions to get the most loop-invariant stuff
 465 // moved out.  We'd like to do all associative operators, but it's especially
 466 // important (common) to do address expressions.
 467 Node* PhaseIdealLoop::remix_address_expressions(Node* n) {
 468   if (!has_ctrl(n))  return NULL;
 469   Node* n_ctrl = get_ctrl(n);
 470   IdealLoopTree* n_loop = get_loop(n_ctrl);
 471 
 472   // See if 'n' mixes loop-varying and loop-invariant inputs and
 473   // itself is loop-varying.
 474 
 475   // Only interested in binary ops (and AddP)
 476   if (n->req() < 3 || n->req() > 4) return NULL;
 477 
 478   Node* n1_ctrl = get_ctrl(n->in(                    1));
 479   Node* n2_ctrl = get_ctrl(n->in(                    2));
 480   Node* n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
 481   IdealLoopTree* n1_loop = get_loop(n1_ctrl);
 482   IdealLoopTree* n2_loop = get_loop(n2_ctrl);
 483   IdealLoopTree* n3_loop = get_loop(n3_ctrl);
 484 
 485   // Does one of my inputs spin in a tighter loop than self?
 486   if ((n_loop->is_member(n1_loop) && n_loop != n1_loop) ||
 487       (n_loop->is_member(n2_loop) && n_loop != n2_loop) ||
 488       (n_loop->is_member(n3_loop) && n_loop != n3_loop)) {
 489     return NULL;                // Leave well enough alone
 490   }
 491 
 492   // Is at least one of my inputs loop-invariant?
 493   if (n1_loop == n_loop &&
 494       n2_loop == n_loop &&
 495       n3_loop == n_loop) {
 496     return NULL;                // No loop-invariant inputs
 497   }
 498 
 499   Node* res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_INT);
 500   if (res != NULL) {
 501     return res;
 502   }
 503   res = remix_address_expressions_add_left_shift(n, n_loop, n_ctrl, T_LONG);
 504   if (res != NULL) {
 505     return res;
 506   }
 507 
 508   int n_op = n->Opcode();
 509   // Replace (I+V) with (V+I)
 510   if (n_op == Op_AddI ||
 511       n_op == Op_AddL ||
 512       n_op == Op_AddF ||
 513       n_op == Op_AddD ||
 514       n_op == Op_MulI ||
 515       n_op == Op_MulL ||
 516       n_op == Op_MulF ||
 517       n_op == Op_MulD) {
 518     if (n2_loop == n_loop) {
 519       assert(n1_loop != n_loop, "");
 520       n->swap_edges(1, 2);
 521     }
 522   }
 523 
 524   // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
 525   // but not if I2 is a constant.
 526   if (n_op == Op_AddP) {
 527     if (n2_loop == n_loop && n3_loop != n_loop) {
 528       if (n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con()) {
 529         Node* n22_ctrl = get_ctrl(n->in(2)->in(2));
 530         Node* n23_ctrl = get_ctrl(n->in(2)->in(3));
 531         IdealLoopTree* n22loop = get_loop(n22_ctrl);
 532         IdealLoopTree* n23_loop = get_loop(n23_ctrl);
 533         if (n22loop != n_loop && n22loop->is_member(n_loop) &&
 534             n23_loop == n_loop) {
 535           Node* add1 = new AddPNode(n->in(1), n->in(2)->in(2), n->in(3));
 536           // Stuff new AddP in the loop preheader
 537           register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
 538           Node* add2 = new AddPNode(n->in(1), add1, n->in(2)->in(3));
 539           register_new_node(add2, n_ctrl);
 540           _igvn.replace_node(n, add2);
 541           return add2;
 542         }
 543       }
 544     }
 545 
 546     // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
 547     if (n2_loop != n_loop && n3_loop == n_loop) {
 548       if (n->in(3)->Opcode() == Op_AddX) {
 549         Node* V = n->in(3)->in(1);
 550         Node* I = n->in(3)->in(2);
 551         if (is_member(n_loop,get_ctrl(V))) {
 552         } else {
 553           Node *tmp = V; V = I; I = tmp;
 554         }
 555         if (!is_member(n_loop,get_ctrl(I))) {
 556           Node* add1 = new AddPNode(n->in(1), n->in(2), I);
 557           // Stuff new AddP in the loop preheader
 558           register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
 559           Node* add2 = new AddPNode(n->in(1), add1, V);
 560           register_new_node(add2, n_ctrl);
 561           _igvn.replace_node(n, add2);
 562           return add2;
 563         }
 564       }
 565     }
 566   }
 567 
 568   return NULL;
 569 }
 570 
 571 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
 572 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
 573   assert(n->Opcode() == Op_AddI, "sanity");
 574   Node * nn = NULL;
 575   Node * in1 = n->in(1);
 576   Node * in2 = n->in(2);
 577   if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
 578     IdealLoopTree* loop_n = get_loop(get_ctrl(n));
 579     if (loop_n->is_counted() &&
 580         loop_n->_head->as_Loop()->is_valid_counted_loop(T_INT) &&
 581         Matcher::match_rule_supported(Op_MulAddVS2VI) &&
 582         Matcher::match_rule_supported(Op_MulAddS2I)) {
 583       Node* mul_in1 = in1->in(1);
 584       Node* mul_in2 = in1->in(2);
 585       Node* mul_in3 = in2->in(1);
 586       Node* mul_in4 = in2->in(2);
 587       if (mul_in1->Opcode() == Op_LoadS &&
 588           mul_in2->Opcode() == Op_LoadS &&
 589           mul_in3->Opcode() == Op_LoadS &&
 590           mul_in4->Opcode() == Op_LoadS) {
 591         IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
 592         IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
 593         IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
 594         IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
 595         IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
 596         IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
 597         // All nodes should be in the same counted loop.
 598         if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
 599             loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
 600           Node* adr1 = mul_in1->in(MemNode::Address);
 601           Node* adr2 = mul_in2->in(MemNode::Address);
 602           Node* adr3 = mul_in3->in(MemNode::Address);
 603           Node* adr4 = mul_in4->in(MemNode::Address);
 604           if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
 605             if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
 606                 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
 607               nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
 608               register_new_node(nn, get_ctrl(n));
 609               _igvn.replace_node(n, nn);
 610               return nn;
 611             } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
 612                        (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
 613               nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
 614               register_new_node(nn, get_ctrl(n));
 615               _igvn.replace_node(n, nn);
 616               return nn;
 617             }
 618           }
 619         }
 620       }
 621     }
 622   }
 623   return nn;
 624 }
 625 
 626 //------------------------------conditional_move-------------------------------
 627 // Attempt to replace a Phi with a conditional move.  We have some pretty
 628 // strict profitability requirements.  All Phis at the merge point must
 629 // be converted, so we can remove the control flow.  We need to limit the
 630 // number of c-moves to a small handful.  All code that was in the side-arms
 631 // of the CFG diamond is now speculatively executed.  This code has to be
 632 // "cheap enough".  We are pretty much limited to CFG diamonds that merge
 633 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
 634 Node *PhaseIdealLoop::conditional_move( Node *region ) {
 635 
 636   assert(region->is_Region(), "sanity check");
 637   if (region->req() != 3) return NULL;
 638 
 639   // Check for CFG diamond
 640   Node *lp = region->in(1);
 641   Node *rp = region->in(2);
 642   if (!lp || !rp) return NULL;
 643   Node *lp_c = lp->in(0);
 644   if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
 645   IfNode *iff = lp_c->as_If();
 646 
 647   // Check for ops pinned in an arm of the diamond.
 648   // Can't remove the control flow in this case
 649   if (lp->outcnt() > 1) return NULL;
 650   if (rp->outcnt() > 1) return NULL;
 651 
 652   IdealLoopTree* r_loop = get_loop(region);
 653   assert(r_loop == get_loop(iff), "sanity");
 654   // Always convert to CMOVE if all results are used only outside this loop.
 655   bool used_inside_loop = (r_loop == _ltree_root);
 656 
 657   // Check profitability
 658   int cost = 0;
 659   int phis = 0;
 660   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 661     Node *out = region->fast_out(i);
 662     if (!out->is_Phi()) continue; // Ignore other control edges, etc
 663     phis++;
 664     PhiNode* phi = out->as_Phi();
 665     BasicType bt = phi->type()->basic_type();
 666     switch (bt) {
 667     case T_DOUBLE:
 668     case T_FLOAT:
 669       if (C->use_cmove()) {
 670         continue; //TODO: maybe we want to add some cost
 671       }
 672       cost += Matcher::float_cmove_cost(); // Could be very expensive
 673       break;
 674     case T_LONG: {
 675       cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
 676     }
 677     case T_INT:                 // These all CMOV fine
 678     case T_ADDRESS: {           // (RawPtr)
 679       cost++;
 680       break;
 681     }
 682     case T_NARROWOOP: // Fall through
 683     case T_OBJECT: {            // Base oops are OK, but not derived oops
 684       const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
 685       // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
 686       // CMOVE'd derived pointer?  It's a CMOVE'd derived base.  Thus
 687       // CMOVE'ing a derived pointer requires we also CMOVE the base.  If we
 688       // have a Phi for the base here that we convert to a CMOVE all is well
 689       // and good.  But if the base is dead, we'll not make a CMOVE.  Later
 690       // the allocator will have to produce a base by creating a CMOVE of the
 691       // relevant bases.  This puts the allocator in the business of
 692       // manufacturing expensive instructions, generally a bad plan.
 693       // Just Say No to Conditionally-Moved Derived Pointers.
 694       if (tp && tp->offset() != 0)
 695         return NULL;
 696       cost++;
 697       break;
 698     }
 699     default:
 700       return NULL;              // In particular, can't do memory or I/O
 701     }
 702     // Add in cost any speculative ops
 703     for (uint j = 1; j < region->req(); j++) {
 704       Node *proj = region->in(j);
 705       Node *inp = phi->in(j);
 706       if (get_ctrl(inp) == proj) { // Found local op
 707         cost++;
 708         // Check for a chain of dependent ops; these will all become
 709         // speculative in a CMOV.
 710         for (uint k = 1; k < inp->req(); k++)
 711           if (get_ctrl(inp->in(k)) == proj)
 712             cost += ConditionalMoveLimit; // Too much speculative goo
 713       }
 714     }
 715     // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
 716     // This will likely Split-If, a higher-payoff operation.
 717     for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
 718       Node* use = phi->fast_out(k);
 719       if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
 720         cost += ConditionalMoveLimit;
 721       // Is there a use inside the loop?
 722       // Note: check only basic types since CMoveP is pinned.
 723       if (!used_inside_loop && is_java_primitive(bt)) {
 724         IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
 725         if (r_loop == u_loop || r_loop->is_member(u_loop)) {
 726           used_inside_loop = true;
 727         }
 728       }
 729     }
 730   }//for
 731   Node* bol = iff->in(1);
 732   if (bol->Opcode() == Op_Opaque4) {
 733     return NULL; // Ignore loop predicate checks (the Opaque4 ensures they will go away)
 734   }
 735   assert(bol->Opcode() == Op_Bool, "Unexpected node");
 736   int cmp_op = bol->in(1)->Opcode();
 737   if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode
 738     return NULL;
 739   }
 740   // It is expensive to generate flags from a float compare.
 741   // Avoid duplicated float compare.
 742   if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
 743 
 744   float infrequent_prob = PROB_UNLIKELY_MAG(3);
 745   // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
 746   if (used_inside_loop) {
 747     if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
 748 
 749     // BlockLayoutByFrequency optimization moves infrequent branch
 750     // from hot path. No point in CMOV'ing in such case (110 is used
 751     // instead of 100 to take into account not exactness of float value).
 752     if (BlockLayoutByFrequency) {
 753       infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
 754     }
 755   }
 756   // Check for highly predictable branch.  No point in CMOV'ing if
 757   // we are going to predict accurately all the time.
 758   if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
 759     //keep going
 760   } else if (iff->_prob < infrequent_prob ||
 761       iff->_prob > (1.0f - infrequent_prob))
 762     return NULL;
 763 
 764   // --------------
 765   // Now replace all Phis with CMOV's
 766   Node *cmov_ctrl = iff->in(0);
 767   uint flip = (lp->Opcode() == Op_IfTrue);
 768   Node_List wq;
 769   while (1) {
 770     PhiNode* phi = NULL;
 771     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 772       Node *out = region->fast_out(i);
 773       if (out->is_Phi()) {
 774         phi = out->as_Phi();
 775         break;
 776       }
 777     }
 778     if (phi == NULL || _igvn.type(phi) == Type::TOP) {
 779       break;
 780     }
 781     if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
 782     // Move speculative ops
 783     wq.push(phi);
 784     while (wq.size() > 0) {
 785       Node *n = wq.pop();
 786       for (uint j = 1; j < n->req(); j++) {
 787         Node* m = n->in(j);
 788         if (m != NULL && !is_dominator(get_ctrl(m), cmov_ctrl)) {
 789 #ifndef PRODUCT
 790           if (PrintOpto && VerifyLoopOptimizations) {
 791             tty->print("  speculate: ");
 792             m->dump();
 793           }
 794 #endif
 795           set_ctrl(m, cmov_ctrl);
 796           wq.push(m);
 797         }
 798       }
 799     }
 800     Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
 801     register_new_node( cmov, cmov_ctrl );
 802     _igvn.replace_node( phi, cmov );
 803 #ifndef PRODUCT
 804     if (TraceLoopOpts) {
 805       tty->print("CMOV  ");
 806       r_loop->dump_head();
 807       if (Verbose) {
 808         bol->in(1)->dump(1);
 809         cmov->dump(1);
 810       }
 811     }
 812     if (VerifyLoopOptimizations) verify();
 813 #endif
 814   }
 815 
 816   // The useless CFG diamond will fold up later; see the optimization in
 817   // RegionNode::Ideal.
 818   _igvn._worklist.push(region);
 819 
 820   return iff->in(1);
 821 }
 822 
 823 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
 824   for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
 825     Node* u = m->fast_out(i);
 826     if (u->is_CFG()) {
 827       if (u->is_NeverBranch()) {
 828         u = u->as_NeverBranch()->proj_out(0);
 829         enqueue_cfg_uses(u, wq);
 830       } else {
 831         wq.push(u);
 832       }
 833     }
 834   }
 835 }
 836 
 837 // Try moving a store out of a loop, right before the loop
 838 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
 839   // Store has to be first in the loop body
 840   IdealLoopTree *n_loop = get_loop(n_ctrl);
 841   if (n->is_Store() && n_loop != _ltree_root &&
 842       n_loop->is_loop() && n_loop->_head->is_Loop() &&
 843       n->in(0) != NULL) {
 844     Node* address = n->in(MemNode::Address);
 845     Node* value = n->in(MemNode::ValueIn);
 846     Node* mem = n->in(MemNode::Memory);
 847     IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 848     IdealLoopTree* value_loop = get_loop(get_ctrl(value));
 849 
 850     // - address and value must be loop invariant
 851     // - memory must be a memory Phi for the loop
 852     // - Store must be the only store on this memory slice in the
 853     // loop: if there's another store following this one then value
 854     // written at iteration i by the second store could be overwritten
 855     // at iteration i+n by the first store: it's not safe to move the
 856     // first store out of the loop
 857     // - nothing must observe the memory Phi: it guarantees no read
 858     // before the store, we are also guaranteed the store post
 859     // dominates the loop head (ignoring a possible early
 860     // exit). Otherwise there would be extra Phi involved between the
 861     // loop's Phi and the store.
 862     // - there must be no early exit from the loop before the Store
 863     // (such an exit most of the time would be an extra use of the
 864     // memory Phi but sometimes is a bottom memory Phi that takes the
 865     // store as input).
 866 
 867     if (!n_loop->is_member(address_loop) &&
 868         !n_loop->is_member(value_loop) &&
 869         mem->is_Phi() && mem->in(0) == n_loop->_head &&
 870         mem->outcnt() == 1 &&
 871         mem->in(LoopNode::LoopBackControl) == n) {
 872 
 873       assert(n_loop->_tail != NULL, "need a tail");
 874       assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
 875 
 876       // Verify that there's no early exit of the loop before the store.
 877       bool ctrl_ok = false;
 878       {
 879         // Follow control from loop head until n, we exit the loop or
 880         // we reach the tail
 881         ResourceMark rm;
 882         Unique_Node_List wq;
 883         wq.push(n_loop->_head);
 884 
 885         for (uint next = 0; next < wq.size(); ++next) {
 886           Node *m = wq.at(next);
 887           if (m == n->in(0)) {
 888             ctrl_ok = true;
 889             continue;
 890           }
 891           assert(!has_ctrl(m), "should be CFG");
 892           if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
 893             ctrl_ok = false;
 894             break;
 895           }
 896           enqueue_cfg_uses(m, wq);
 897           if (wq.size() > 10) {
 898             ctrl_ok = false;
 899             break;
 900           }
 901         }
 902       }
 903       if (ctrl_ok) {
 904         // move the Store
 905         _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
 906         _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
 907         _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
 908         // Disconnect the phi now. An empty phi can confuse other
 909         // optimizations in this pass of loop opts.
 910         _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
 911         n_loop->_body.yank(mem);
 912 
 913         set_ctrl_and_loop(n, n->in(0));
 914 
 915         return n;
 916       }
 917     }
 918   }
 919   return NULL;
 920 }
 921 
 922 // Try moving a store out of a loop, right after the loop
 923 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
 924   if (n->is_Store() && n->in(0) != NULL) {
 925     Node *n_ctrl = get_ctrl(n);
 926     IdealLoopTree *n_loop = get_loop(n_ctrl);
 927     // Store must be in a loop
 928     if (n_loop != _ltree_root && !n_loop->_irreducible) {
 929       Node* address = n->in(MemNode::Address);
 930       Node* value = n->in(MemNode::ValueIn);
 931       IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 932       // address must be loop invariant
 933       if (!n_loop->is_member(address_loop)) {
 934         // Store must be last on this memory slice in the loop and
 935         // nothing in the loop must observe it
 936         Node* phi = NULL;
 937         for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 938           Node* u = n->fast_out(i);
 939           if (has_ctrl(u)) { // control use?
 940             IdealLoopTree *u_loop = get_loop(get_ctrl(u));
 941             if (!n_loop->is_member(u_loop)) {
 942               continue;
 943             }
 944             if (u->is_Phi() && u->in(0) == n_loop->_head) {
 945               assert(_igvn.type(u) == Type::MEMORY, "bad phi");
 946               // multiple phis on the same slice are possible
 947               if (phi != NULL) {
 948                 return;
 949               }
 950               phi = u;
 951               continue;
 952             }
 953           }
 954           return;
 955         }
 956         if (phi != NULL) {
 957           // Nothing in the loop before the store (next iteration)
 958           // must observe the stored value
 959           bool mem_ok = true;
 960           {
 961             ResourceMark rm;
 962             Unique_Node_List wq;
 963             wq.push(phi);
 964             for (uint next = 0; next < wq.size() && mem_ok; ++next) {
 965               Node *m = wq.at(next);
 966               for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
 967                 Node* u = m->fast_out(i);
 968                 if (u->is_Store() || u->is_Phi()) {
 969                   if (u != n) {
 970                     wq.push(u);
 971                     mem_ok = (wq.size() <= 10);
 972                   }
 973                 } else {
 974                   mem_ok = false;
 975                   break;
 976                 }
 977               }
 978             }
 979           }
 980           if (mem_ok) {
 981             // Move the store out of the loop if the LCA of all
 982             // users (except for the phi) is outside the loop.
 983             Node* hook = new Node(1);
 984             hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
 985             _igvn.rehash_node_delayed(phi);
 986             int count = phi->replace_edge(n, hook, &_igvn);
 987             assert(count > 0, "inconsistent phi");
 988 
 989             // Compute latest point this store can go
 990             Node* lca = get_late_ctrl(n, get_ctrl(n));
 991             if (lca->is_OuterStripMinedLoop()) {
 992               lca = lca->in(LoopNode::EntryControl);
 993             }
 994             if (n_loop->is_member(get_loop(lca))) {
 995               // LCA is in the loop - bail out
 996               _igvn.replace_node(hook, n);
 997               return;
 998             }
 999 #ifdef ASSERT
1000             if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
1001               assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
1002               n_loop->_head->as_Loop()->verify_strip_mined(1);
1003               Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
1004               IdealLoopTree* outer_loop = get_loop(outer);
1005               assert(n_loop->_parent == outer_loop, "broken loop tree");
1006               assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
1007             }
1008 #endif
1009             lca = place_outside_loop(lca, n_loop);
1010             assert(!n_loop->is_member(get_loop(lca)), "control must not be back in the loop");
1011             assert(get_loop(lca)->_nest < n_loop->_nest || lca->in(0)->is_NeverBranch(), "must not be moved into inner loop");
1012 
1013             // Move store out of the loop
1014             _igvn.replace_node(hook, n->in(MemNode::Memory));
1015             _igvn.replace_input_of(n, 0, lca);
1016             set_ctrl_and_loop(n, lca);
1017 
1018             // Disconnect the phi now. An empty phi can confuse other
1019             // optimizations in this pass of loop opts..
1020             if (phi->in(LoopNode::LoopBackControl) == phi) {
1021               _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
1022               n_loop->_body.yank(phi);
1023             }
1024           }
1025         }
1026       }
1027     }
1028   }
1029 }
1030 
1031 // If UseArrayMarkWordCheck is enabled, we can't use immutable memory for the flat array check
1032 // because we are loading the mark word which is mutable. Although the bits we are interested in
1033 // are immutable (we check for markWord::unlocked_value), we need to use raw memory to not break
1034 // anti dependency analysis. Below code will attempt to still move flat array checks out of loops,
1035 // mainly to enable loop unswitching.
1036 void PhaseIdealLoop::move_flat_array_check_out_of_loop(Node* n) {
1037   // Skip checks for more than one array
1038   if (n->req() > 3) {
1039     return;
1040   }
1041   Node* mem = n->in(FlatArrayCheckNode::Memory);
1042   Node* array = n->in(FlatArrayCheckNode::ArrayOrKlass)->uncast();
1043   IdealLoopTree* check_loop = get_loop(get_ctrl(n));
1044   IdealLoopTree* ary_loop = get_loop(get_ctrl(array));
1045 
1046   // Check if array is loop invariant
1047   if (!check_loop->is_member(ary_loop)) {
1048     // Walk up memory graph from the check until we leave the loop
1049     VectorSet wq;
1050     wq.set(mem->_idx);
1051     while (check_loop->is_member(get_loop(ctrl_or_self(mem)))) {
1052       if (mem->is_Phi()) {
1053         mem = mem->in(1);
1054       } else if (mem->is_MergeMem()) {
1055         mem = mem->as_MergeMem()->memory_at(Compile::AliasIdxRaw);
1056       } else if (mem->is_Proj()) {
1057         mem = mem->in(0);
1058       } else if (mem->is_MemBar() || mem->is_SafePoint()) {
1059         mem = mem->in(TypeFunc::Memory);
1060       } else if (mem->is_Store() || mem->is_LoadStore() || mem->is_ClearArray()) {
1061         mem = mem->in(MemNode::Memory);
1062       } else {
1063 #ifdef ASSERT
1064         mem->dump();
1065 #endif
1066         ShouldNotReachHere();
1067       }
1068       if (wq.test_set(mem->_idx)) {
1069         return;
1070       }
1071     }
1072     // Replace memory input and re-compute ctrl to move the check out of the loop
1073     _igvn.replace_input_of(n, 1, mem);
1074     set_ctrl_and_loop(n, get_early_ctrl(n));
1075     Node* bol = n->unique_out();
1076     set_ctrl_and_loop(bol, get_early_ctrl(bol));
1077   }
1078 }
1079 
1080 //------------------------------split_if_with_blocks_pre-----------------------
1081 // Do the real work in a non-recursive function.  Data nodes want to be
1082 // cloned in the pre-order so they can feed each other nicely.
1083 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
1084   // Cloning these guys is unlikely to win
1085   int n_op = n->Opcode();
1086   if (n_op == Op_MergeMem) {
1087     return n;
1088   }
1089   if (n->is_Proj()) {
1090     return n;
1091   }
1092 
1093   if (UseArrayMarkWordCheck && n->isa_FlatArrayCheck()) {
1094     move_flat_array_check_out_of_loop(n);
1095     return n;
1096   }
1097 
1098   // Do not clone-up CmpFXXX variations, as these are always
1099   // followed by a CmpI
1100   if (n->is_Cmp()) {
1101     return n;
1102   }
1103   // Attempt to use a conditional move instead of a phi/branch
1104   if (ConditionalMoveLimit > 0 && n_op == Op_Region) {
1105     Node *cmov = conditional_move( n );
1106     if (cmov) {
1107       return cmov;
1108     }
1109   }
1110   if (n->is_CFG() || n->is_LoadStore()) {
1111     return n;
1112   }
1113   if (n->is_Opaque1()) { // Opaque nodes cannot be mod'd
1114     if (!C->major_progress()) {   // If chance of no more loop opts...
1115       _igvn._worklist.push(n);  // maybe we'll remove them
1116     }
1117     return n;
1118   }
1119 
1120   if (n->is_Con()) {
1121     return n;   // No cloning for Con nodes
1122   }
1123 
1124   Node *n_ctrl = get_ctrl(n);
1125   if (!n_ctrl) {
1126     return n;       // Dead node
1127   }
1128 
1129   Node* res = try_move_store_before_loop(n, n_ctrl);
1130   if (res != NULL) {
1131     return n;
1132   }
1133 
1134   // Attempt to remix address expressions for loop invariants
1135   Node *m = remix_address_expressions( n );
1136   if( m ) return m;
1137 
1138   if (n_op == Op_AddI) {
1139     Node *nn = convert_add_to_muladd( n );
1140     if ( nn ) return nn;
1141   }
1142 
1143   if (n->is_ConstraintCast()) {
1144     Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
1145     // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
1146     // Node control inputs don't necessarily agree with loop control info (due to
1147     // transformations happened in between), thus additional dominance check is needed
1148     // to keep loop info valid.
1149     if (dom_cast != NULL && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1150       _igvn.replace_node(n, dom_cast);
1151       return dom_cast;
1152     }
1153   }
1154 
1155   // Determine if the Node has inputs from some local Phi.
1156   // Returns the block to clone thru.
1157   Node *n_blk = has_local_phi_input( n );
1158   if( !n_blk ) return n;
1159 
1160   // Do not clone the trip counter through on a CountedLoop
1161   // (messes up the canonical shape).
1162   if (((n_blk->is_CountedLoop() || (n_blk->is_Loop() && n_blk->as_Loop()->is_loop_nest_inner_loop())) && n->Opcode() == Op_AddI) ||
1163       (n_blk->is_LongCountedLoop() && n->Opcode() == Op_AddL)) {
1164     return n;
1165   }
1166   // Pushing a shift through the iv Phi can get in the way of addressing optimizations or range check elimination
1167   if (n_blk->is_BaseCountedLoop() && n->Opcode() == Op_LShift(n_blk->as_BaseCountedLoop()->bt()) &&
1168       n->in(1) == n_blk->as_BaseCountedLoop()->phi()) {
1169     return n;
1170   }
1171 
1172   // Check for having no control input; not pinned.  Allow
1173   // dominating control.
1174   if (n->in(0)) {
1175     Node *dom = idom(n_blk);
1176     if (dom_lca(n->in(0), dom) != n->in(0)) {
1177       return n;
1178     }
1179   }
1180   // Policy: when is it profitable.  You must get more wins than
1181   // policy before it is considered profitable.  Policy is usually 0,
1182   // so 1 win is considered profitable.  Big merges will require big
1183   // cloning, so get a larger policy.
1184   int policy = n_blk->req() >> 2;
1185 
1186   // If the loop is a candidate for range check elimination,
1187   // delay splitting through it's phi until a later loop optimization
1188   if (n_blk->is_BaseCountedLoop()) {
1189     IdealLoopTree *lp = get_loop(n_blk);
1190     if (lp && lp->_rce_candidate) {
1191       return n;
1192     }
1193   }
1194 
1195   if (must_throttle_split_if()) return n;
1196 
1197   // Split 'n' through the merge point if it is profitable
1198   Node *phi = split_thru_phi( n, n_blk, policy );
1199   if (!phi) return n;
1200 
1201   // Found a Phi to split thru!
1202   // Replace 'n' with the new phi
1203   _igvn.replace_node( n, phi );
1204   // Moved a load around the loop, 'en-registering' something.
1205   if (n_blk->is_Loop() && n->is_Load() &&
1206       !phi->in(LoopNode::LoopBackControl)->is_Load())
1207     C->set_major_progress();
1208 
1209   return phi;
1210 }
1211 
1212 static bool merge_point_too_heavy(Compile* C, Node* region) {
1213   // Bail out if the region and its phis have too many users.
1214   int weight = 0;
1215   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1216     weight += region->fast_out(i)->outcnt();
1217   }
1218   int nodes_left = C->max_node_limit() - C->live_nodes();
1219   if (weight * 8 > nodes_left) {
1220     if (PrintOpto) {
1221       tty->print_cr("*** Split-if bails out:  %d nodes, region weight %d", C->unique(), weight);
1222     }
1223     return true;
1224   } else {
1225     return false;
1226   }
1227 }
1228 
1229 static bool merge_point_safe(Node* region) {
1230   // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1231   // having a PhiNode input. This sidesteps the dangerous case where the split
1232   // ConvI2LNode may become TOP if the input Value() does not
1233   // overlap the ConvI2L range, leaving a node which may not dominate its
1234   // uses.
1235   // A better fix for this problem can be found in the BugTraq entry, but
1236   // expediency for Mantis demands this hack.
1237 #ifdef _LP64
1238   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1239     Node* n = region->fast_out(i);
1240     if (n->is_Phi()) {
1241       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1242         Node* m = n->fast_out(j);
1243         if (m->Opcode() == Op_ConvI2L)
1244           return false;
1245         if (m->is_CastII()) {
1246           return false;
1247         }
1248       }
1249     }
1250   }
1251 #endif
1252   return true;
1253 }
1254 
1255 
1256 //------------------------------place_outside_loop---------------------------------
1257 // Place some computation outside of this loop on the path to the use passed as argument
1258 Node* PhaseIdealLoop::place_outside_loop(Node* useblock, IdealLoopTree* loop) const {
1259   Node* head = loop->_head;
1260   assert(!loop->is_member(get_loop(useblock)), "must be outside loop");
1261   if (head->is_Loop() && head->as_Loop()->is_strip_mined()) {
1262     loop = loop->_parent;
1263     assert(loop->_head->is_OuterStripMinedLoop(), "malformed strip mined loop");
1264   }
1265 
1266   // Pick control right outside the loop
1267   for (;;) {
1268     Node* dom = idom(useblock);
1269     if (loop->is_member(get_loop(dom)) ||
1270         // NeverBranch nodes are not assigned to the loop when constructed
1271         (dom->is_NeverBranch() && loop->is_member(get_loop(dom->in(0))))) {
1272       break;
1273     }
1274     useblock = dom;
1275   }
1276   assert(find_non_split_ctrl(useblock) == useblock, "should be non split control");
1277   return useblock;
1278 }
1279 
1280 
1281 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1282   if (!n->is_If() || n->is_BaseCountedLoopEnd()) {
1283     return false;
1284   }
1285   if (!n->in(0)->is_Region()) {
1286     return false;
1287   }
1288 
1289   Node* region = n->in(0);
1290   Node* dom = idom(region);
1291   if (!dom->is_If() || dom->in(1) != n->in(1)) {
1292     return false;
1293   }
1294   IfNode* dom_if = dom->as_If();
1295   Node* proj_true = dom_if->proj_out(1);
1296   Node* proj_false = dom_if->proj_out(0);
1297 
1298   for (uint i = 1; i < region->req(); i++) {
1299     if (is_dominator(proj_true, region->in(i))) {
1300       continue;
1301     }
1302     if (is_dominator(proj_false, region->in(i))) {
1303       continue;
1304     }
1305     return false;
1306   }
1307 
1308   return true;
1309 }
1310 
1311 
1312 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1313   if (must_throttle_split_if()) {
1314     return false;
1315   }
1316 
1317   // Do not do 'split-if' if irreducible loops are present.
1318   if (_has_irreducible_loops) {
1319     return false;
1320   }
1321 
1322   if (merge_point_too_heavy(C, n_ctrl)) {
1323     return false;
1324   }
1325 
1326   // Do not do 'split-if' if some paths are dead.  First do dead code
1327   // elimination and then see if its still profitable.
1328   for (uint i = 1; i < n_ctrl->req(); i++) {
1329     if (n_ctrl->in(i) == C->top()) {
1330       return false;
1331     }
1332   }
1333 
1334   // If trying to do a 'Split-If' at the loop head, it is only
1335   // profitable if the cmp folds up on BOTH paths.  Otherwise we
1336   // risk peeling a loop forever.
1337 
1338   // CNC - Disabled for now.  Requires careful handling of loop
1339   // body selection for the cloned code.  Also, make sure we check
1340   // for any input path not being in the same loop as n_ctrl.  For
1341   // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1342   // because the alternative loop entry points won't be converted
1343   // into LoopNodes.
1344   IdealLoopTree *n_loop = get_loop(n_ctrl);
1345   for (uint j = 1; j < n_ctrl->req(); j++) {
1346     if (get_loop(n_ctrl->in(j)) != n_loop) {
1347       return false;
1348     }
1349   }
1350 
1351   // Check for safety of the merge point.
1352   if (!merge_point_safe(n_ctrl)) {
1353     return false;
1354   }
1355 
1356   return true;
1357 }
1358 
1359 // Detect if the node is the inner strip-mined loop
1360 // Return: NULL if it's not the case, or the exit of outer strip-mined loop
1361 static Node* is_inner_of_stripmined_loop(const Node* out) {
1362   Node* out_le = NULL;
1363 
1364   if (out->is_CountedLoopEnd()) {
1365       const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1366 
1367       if (loop != NULL && loop->is_strip_mined()) {
1368         out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1369       }
1370   }
1371 
1372   return out_le;
1373 }
1374 
1375 bool PhaseIdealLoop::flatten_array_element_type_check(Node *n) {
1376   // If the CmpP is a subtype check for a value that has just been
1377   // loaded from an array, the subtype check guarantees the value
1378   // can't be stored in a flattened array and the load of the value
1379   // happens with a flattened array check then: push the type check
1380   // through the phi of the flattened array check. This needs special
1381   // logic because the subtype check's input is not a phi but a
1382   // LoadKlass that must first be cloned through the phi.
1383   if (n->Opcode() != Op_CmpP) {
1384     return false;
1385   }
1386 
1387   Node* klassptr = n->in(1);
1388   Node* klasscon = n->in(2);
1389 
1390   if (klassptr->is_DecodeNarrowPtr()) {
1391     klassptr = klassptr->in(1);
1392   }
1393 
1394   if (klassptr->Opcode() != Op_LoadKlass && klassptr->Opcode() != Op_LoadNKlass) {
1395     return false;
1396   }
1397 
1398   if (!klasscon->is_Con()) {
1399     return false;
1400   }
1401 
1402   Node* addr = klassptr->in(MemNode::Address);
1403 
1404   if (!addr->is_AddP()) {
1405     return false;
1406   }
1407 
1408   intptr_t offset;
1409   Node* obj = AddPNode::Ideal_base_and_offset(addr, &_igvn, offset);
1410 
1411   if (obj == NULL) {
1412     return false;
1413   }
1414 
1415   assert(obj != NULL && addr->in(AddPNode::Base) == addr->in(AddPNode::Address), "malformed AddP?");
1416   if (obj->Opcode() == Op_CastPP) {
1417     obj = obj->in(1);
1418   }
1419 
1420   if (!obj->is_Phi()) {
1421     return false;
1422   }
1423 
1424   Node* region = obj->in(0);
1425 
1426   Node* phi = PhiNode::make_blank(region, n->in(1));
1427   for (uint i = 1; i < region->req(); i++) {
1428     Node* in = obj->in(i);
1429     Node* ctrl = region->in(i);
1430     if (addr->in(AddPNode::Base) != obj) {
1431       Node* cast = addr->in(AddPNode::Base);
1432       assert(cast->Opcode() == Op_CastPP && cast->in(0) != NULL, "inconsistent subgraph");
1433       Node* cast_clone = cast->clone();
1434       cast_clone->set_req(0, ctrl);
1435       cast_clone->set_req(1, in);
1436       register_new_node(cast_clone, ctrl);
1437       const Type* tcast = cast_clone->Value(&_igvn);
1438       _igvn.set_type(cast_clone, tcast);
1439       cast_clone->as_Type()->set_type(tcast);
1440       in = cast_clone;
1441     }
1442     Node* addr_clone = addr->clone();
1443     addr_clone->set_req(AddPNode::Base, in);
1444     addr_clone->set_req(AddPNode::Address, in);
1445     register_new_node(addr_clone, ctrl);
1446     _igvn.set_type(addr_clone, addr_clone->Value(&_igvn));
1447     Node* klassptr_clone = klassptr->clone();
1448     klassptr_clone->set_req(2, addr_clone);
1449     register_new_node(klassptr_clone, ctrl);
1450     _igvn.set_type(klassptr_clone, klassptr_clone->Value(&_igvn));
1451     if (klassptr != n->in(1)) {
1452       Node* decode = n->in(1);
1453       assert(decode->is_DecodeNarrowPtr(), "inconsistent subgraph");
1454       Node* decode_clone = decode->clone();
1455       decode_clone->set_req(1, klassptr_clone);
1456       register_new_node(decode_clone, ctrl);
1457       _igvn.set_type(decode_clone, decode_clone->Value(&_igvn));
1458       klassptr_clone = decode_clone;
1459     }
1460     phi->set_req(i, klassptr_clone);
1461   }
1462   register_new_node(phi, region);
1463   Node* orig = n->in(1);
1464   _igvn.replace_input_of(n, 1, phi);
1465   split_if_with_blocks_post(n);
1466   if (n->outcnt() != 0) {
1467     _igvn.replace_input_of(n, 1, orig);
1468     _igvn.remove_dead_node(phi);
1469   }
1470   return true;
1471 }
1472 
1473 //------------------------------split_if_with_blocks_post----------------------
1474 // Do the real work in a non-recursive function.  CFG hackery wants to be
1475 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1476 // info.
1477 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1478 
1479   if (flatten_array_element_type_check(n)) {
1480     return;
1481   }
1482 
1483   // Cloning Cmp through Phi's involves the split-if transform.
1484   // FastLock is not used by an If
1485   if (n->is_Cmp() && !n->is_FastLock()) {
1486     Node *n_ctrl = get_ctrl(n);
1487     // Determine if the Node has inputs from some local Phi.
1488     // Returns the block to clone thru.
1489     Node *n_blk = has_local_phi_input(n);
1490     if (n_blk != n_ctrl) {
1491       return;
1492     }
1493 
1494     if (!can_split_if(n_ctrl)) {
1495       return;
1496     }
1497 
1498     if (n->outcnt() != 1) {
1499       return; // Multiple bool's from 1 compare?
1500     }
1501     Node *bol = n->unique_out();
1502     assert(bol->is_Bool(), "expect a bool here");
1503     if (bol->outcnt() != 1) {
1504       return;// Multiple branches from 1 compare?
1505     }
1506     Node *iff = bol->unique_out();
1507 
1508     // Check some safety conditions
1509     if (iff->is_If()) {        // Classic split-if?
1510       if (iff->in(0) != n_ctrl) {
1511         return; // Compare must be in same blk as if
1512       }
1513     } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1514       // Can't split CMove with different control edge.
1515       if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) {
1516         return;
1517       }
1518       if (get_ctrl(iff->in(2)) == n_ctrl ||
1519           get_ctrl(iff->in(3)) == n_ctrl) {
1520         return;                 // Inputs not yet split-up
1521       }
1522       if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1523         return;                 // Loop-invar test gates loop-varying CMOVE
1524       }
1525     } else {
1526       return;  // some other kind of node, such as an Allocate
1527     }
1528 
1529     // When is split-if profitable?  Every 'win' on means some control flow
1530     // goes dead, so it's almost always a win.
1531     int policy = 0;
1532     // Split compare 'n' through the merge point if it is profitable
1533     Node *phi = split_thru_phi( n, n_ctrl, policy);
1534     if (!phi) {
1535       return;
1536     }
1537 
1538     // Found a Phi to split thru!
1539     // Replace 'n' with the new phi
1540     _igvn.replace_node(n, phi);
1541 
1542     // Now split the bool up thru the phi
1543     Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1544     guarantee(bolphi != NULL, "null boolean phi node");
1545 
1546     _igvn.replace_node(bol, bolphi);
1547     assert(iff->in(1) == bolphi, "");
1548 
1549     if (bolphi->Value(&_igvn)->singleton()) {
1550       return;
1551     }
1552 
1553     // Conditional-move?  Must split up now
1554     if (!iff->is_If()) {
1555       Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1556       _igvn.replace_node(iff, cmovphi);
1557       return;
1558     }
1559 
1560     // Now split the IF
1561     do_split_if(iff);
1562     return;
1563   }
1564 
1565   // Two identical ifs back to back can be merged
1566   if (try_merge_identical_ifs(n)) {
1567     return;
1568   }
1569 
1570   // Check for an IF ready to split; one that has its
1571   // condition codes input coming from a Phi at the block start.
1572   int n_op = n->Opcode();
1573 
1574   // Check for an IF being dominated by another IF same test
1575   if (n_op == Op_If ||
1576       n_op == Op_RangeCheck) {
1577     Node *bol = n->in(1);
1578     uint max = bol->outcnt();
1579     // Check for same test used more than once?
1580     if (max > 1 && bol->is_Bool()) {
1581       // Search up IDOMs to see if this IF is dominated.
1582       Node *cutoff = get_ctrl(bol);
1583 
1584       // Now search up IDOMs till cutoff, looking for a dominating test
1585       Node *prevdom = n;
1586       Node *dom = idom(prevdom);
1587       while (dom != cutoff) {
1588         if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom &&
1589             safe_for_if_replacement(dom)) {
1590           // It's invalid to move control dependent data nodes in the inner
1591           // strip-mined loop, because:
1592           //  1) break validation of LoopNode::verify_strip_mined()
1593           //  2) move code with side-effect in strip-mined loop
1594           // Move to the exit of outer strip-mined loop in that case.
1595           Node* out_le = is_inner_of_stripmined_loop(dom);
1596           if (out_le != NULL) {
1597             prevdom = out_le;
1598           }
1599           // Replace the dominated test with an obvious true or false.
1600           // Place it on the IGVN worklist for later cleanup.
1601           C->set_major_progress();
1602           dominated_by(prevdom->as_IfProj(), n->as_If(), false, true);
1603 #ifndef PRODUCT
1604           if( VerifyLoopOptimizations ) verify();
1605 #endif
1606           return;
1607         }
1608         prevdom = dom;
1609         dom = idom(prevdom);
1610       }
1611     }
1612   }
1613 
1614   try_sink_out_of_loop(n);
1615 
1616   try_move_store_after_loop(n);
1617 
1618   // Remove multiple allocations of the same inline type
1619   if (n->is_InlineType()) {
1620     n->as_InlineType()->remove_redundant_allocations(this);
1621   }
1622 }
1623 
1624 // Transform:
1625 //
1626 // if (some_condition) {
1627 //   // body 1
1628 // } else {
1629 //   // body 2
1630 // }
1631 // if (some_condition) {
1632 //   // body 3
1633 // } else {
1634 //   // body 4
1635 // }
1636 //
1637 // into:
1638 //
1639 //
1640 // if (some_condition) {
1641 //   // body 1
1642 //   // body 3
1643 // } else {
1644 //   // body 2
1645 //   // body 4
1646 // }
1647 bool PhaseIdealLoop::try_merge_identical_ifs(Node* n) {
1648   if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1649     Node *n_ctrl = n->in(0);
1650     IfNode* dom_if = idom(n_ctrl)->as_If();
1651     ProjNode* dom_proj_true = dom_if->proj_out(1);
1652     ProjNode* dom_proj_false = dom_if->proj_out(0);
1653 
1654     // Now split the IF
1655     RegionNode* new_false_region;
1656     RegionNode* new_true_region;
1657     do_split_if(n, &new_false_region, &new_true_region);
1658     assert(new_false_region->req() == new_true_region->req(), "");
1659 #ifdef ASSERT
1660     for (uint i = 1; i < new_false_region->req(); ++i) {
1661       assert(new_false_region->in(i)->in(0) == new_true_region->in(i)->in(0), "unexpected shape following split if");
1662       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");
1663     }
1664 #endif
1665     assert(new_false_region->in(1)->in(0)->in(1) == dom_if->in(1), "dominating if and dominated if after split must share test");
1666 
1667     // We now have:
1668     // if (some_condition) {
1669     //   // body 1
1670     //   if (some_condition) {
1671     //     body3: // new_true_region
1672     //     // body3
1673     //   } else {
1674     //     goto body4;
1675     //   }
1676     // } else {
1677     //   // body 2
1678     //  if (some_condition) {
1679     //     goto body3;
1680     //   } else {
1681     //     body4:   // new_false_region
1682     //     // body4;
1683     //   }
1684     // }
1685     //
1686 
1687     // clone pinned nodes thru the resulting regions
1688     push_pinned_nodes_thru_region(dom_if, new_true_region);
1689     push_pinned_nodes_thru_region(dom_if, new_false_region);
1690 
1691     // Optimize out the cloned ifs. Because pinned nodes were cloned, this also allows a CastPP that would be dependent
1692     // 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
1693     // unrelated control dependency.
1694     for (uint i = 1; i < new_false_region->req(); i++) {
1695       if (is_dominator(dom_proj_true, new_false_region->in(i))) {
1696         dominated_by(dom_proj_true->as_IfProj(), new_false_region->in(i)->in(0)->as_If(), false, false);
1697       } else {
1698         assert(is_dominator(dom_proj_false, new_false_region->in(i)), "bad if");
1699         dominated_by(dom_proj_false->as_IfProj(), new_false_region->in(i)->in(0)->as_If(), false, false);
1700       }
1701     }
1702     return true;
1703   }
1704   return false;
1705 }
1706 
1707 void PhaseIdealLoop::push_pinned_nodes_thru_region(IfNode* dom_if, Node* region) {
1708   for (DUIterator i = region->outs(); region->has_out(i); i++) {
1709     Node* u = region->out(i);
1710     if (!has_ctrl(u) || u->is_Phi() || !u->depends_only_on_test() || !_igvn.no_dependent_zero_check(u)) {
1711       continue;
1712     }
1713     assert(u->in(0) == region, "not a control dependent node?");
1714     uint j = 1;
1715     for (; j < u->req(); ++j) {
1716       Node* in = u->in(j);
1717       if (!is_dominator(ctrl_or_self(in), dom_if)) {
1718         break;
1719       }
1720     }
1721     if (j == u->req()) {
1722       Node *phi = PhiNode::make_blank(region, u);
1723       for (uint k = 1; k < region->req(); ++k) {
1724         Node* clone = u->clone();
1725         clone->set_req(0, region->in(k));
1726         register_new_node(clone, region->in(k));
1727         phi->init_req(k, clone);
1728       }
1729       register_new_node(phi, region);
1730       _igvn.replace_node(u, phi);
1731       --i;
1732     }
1733   }
1734 }
1735 
1736 bool PhaseIdealLoop::safe_for_if_replacement(const Node* dom) const {
1737   if (!dom->is_CountedLoopEnd()) {
1738     return true;
1739   }
1740   CountedLoopEndNode* le = dom->as_CountedLoopEnd();
1741   CountedLoopNode* cl = le->loopnode();
1742   if (cl == NULL) {
1743     return true;
1744   }
1745   if (!cl->is_main_loop()) {
1746     return true;
1747   }
1748   if (cl->is_canonical_loop_entry() == NULL) {
1749     return true;
1750   }
1751   // Further unrolling is possible so loop exit condition might change
1752   return false;
1753 }
1754 
1755 // See if a shared loop-varying computation has no loop-varying uses.
1756 // Happens if something is only used for JVM state in uncommon trap exits,
1757 // like various versions of induction variable+offset.  Clone the
1758 // computation per usage to allow it to sink out of the loop.
1759 void PhaseIdealLoop::try_sink_out_of_loop(Node* n) {
1760   if (has_ctrl(n) &&
1761       !n->is_Phi() &&
1762       !n->is_Bool() &&
1763       !n->is_Proj() &&
1764       !n->is_MergeMem() &&
1765       !n->is_CMove() &&
1766       n->Opcode() != Op_Opaque4 &&
1767       !n->is_Type()) {
1768     Node *n_ctrl = get_ctrl(n);
1769     IdealLoopTree *n_loop = get_loop(n_ctrl);
1770 
1771     if (n->in(0) != NULL) {
1772       IdealLoopTree* loop_ctrl = get_loop(n->in(0));
1773       if (n_loop != loop_ctrl && n_loop->is_member(loop_ctrl)) {
1774         // n has a control input inside a loop but get_ctrl() is member of an outer loop. This could happen, for example,
1775         // for Div nodes inside a loop (control input inside loop) without a use except for an UCT (outside the loop).
1776         // Rewire control of n to right outside of the loop, regardless if its input(s) are later sunk or not.
1777         _igvn.replace_input_of(n, 0, place_outside_loop(n_ctrl, loop_ctrl));
1778       }
1779     }
1780     if (n_loop != _ltree_root && n->outcnt() > 1) {
1781       // Compute early control: needed for anti-dependence analysis. It's also possible that as a result of
1782       // previous transformations in this loop opts round, the node can be hoisted now: early control will tell us.
1783       Node* early_ctrl = compute_early_ctrl(n, n_ctrl);
1784       if (n_loop->is_member(get_loop(early_ctrl)) && // check that this one can't be hoisted now
1785           ctrl_of_all_uses_out_of_loop(n, early_ctrl, n_loop)) { // All uses in outer loops!
1786         assert(!n->is_Store() && !n->is_LoadStore(), "no node with a side effect");
1787         Node* outer_loop_clone = NULL;
1788         for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin;) {
1789           Node* u = n->last_out(j); // Clone private computation per use
1790           _igvn.rehash_node_delayed(u);
1791           Node* x = n->clone(); // Clone computation
1792           Node* x_ctrl = NULL;
1793           if (u->is_Phi()) {
1794             // Replace all uses of normal nodes.  Replace Phi uses
1795             // individually, so the separate Nodes can sink down
1796             // different paths.
1797             uint k = 1;
1798             while (u->in(k) != n) k++;
1799             u->set_req(k, x);
1800             // x goes next to Phi input path
1801             x_ctrl = u->in(0)->in(k);
1802             // Find control for 'x' next to use but not inside inner loops.
1803             x_ctrl = place_outside_loop(x_ctrl, n_loop);
1804             --j;
1805           } else {              // Normal use
1806             if (has_ctrl(u)) {
1807               x_ctrl = get_ctrl(u);
1808             } else {
1809               x_ctrl = u->in(0);
1810             }
1811             // Find control for 'x' next to use but not inside inner loops.
1812             x_ctrl = place_outside_loop(x_ctrl, n_loop);
1813             // Replace all uses
1814             if (u->is_ConstraintCast() && u->bottom_type()->higher_equal(_igvn.type(n)) && u->in(0) == x_ctrl) {
1815               // If we're sinking a chain of data nodes, we might have inserted a cast to pin the use which is not necessary
1816               // anymore now that we're going to pin n as well
1817               _igvn.replace_node(u, x);
1818               --j;
1819             } else {
1820               int nb = u->replace_edge(n, x, &_igvn);
1821               j -= nb;
1822             }
1823           }
1824 
1825           if (n->is_Load()) {
1826             // For loads, add a control edge to a CFG node outside of the loop
1827             // to force them to not combine and return back inside the loop
1828             // during GVN optimization (4641526).
1829             assert(x_ctrl == get_late_ctrl_with_anti_dep(x->as_Load(), early_ctrl, x_ctrl), "anti-dependences were already checked");
1830 
1831             IdealLoopTree* x_loop = get_loop(x_ctrl);
1832             Node* x_head = x_loop->_head;
1833             if (x_head->is_Loop() && x_head->is_OuterStripMinedLoop()) {
1834               // Do not add duplicate LoadNodes to the outer strip mined loop
1835               if (outer_loop_clone != NULL) {
1836                 _igvn.replace_node(x, outer_loop_clone);
1837                 continue;
1838               }
1839               outer_loop_clone = x;
1840             }
1841             x->set_req(0, x_ctrl);
1842           } else if (n->in(0) != NULL){
1843             x->set_req(0, x_ctrl);
1844           }
1845           assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1846           assert(!n_loop->is_member(get_loop(x_ctrl)), "should have moved out of loop");
1847           register_new_node(x, x_ctrl);
1848 
1849           // Chain of AddP: (AddP base (AddP base )) must keep the same base after sinking so:
1850           // 1- We don't add a CastPP here when the first one is sunk so if the second one is not, their bases remain
1851           // the same.
1852           // (see 2- below)
1853           assert(!x->is_AddP() || !x->in(AddPNode::Address)->is_AddP() ||
1854                  x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base) ||
1855                  !x->in(AddPNode::Address)->in(AddPNode::Base)->eqv_uncast(x->in(AddPNode::Base)), "unexpected AddP shape");
1856           if (x->in(0) == NULL && !x->is_DecodeNarrowPtr() &&
1857               !(x->is_AddP() && x->in(AddPNode::Address)->is_AddP() && x->in(AddPNode::Address)->in(AddPNode::Base) == x->in(AddPNode::Base))) {
1858             assert(!x->is_Load(), "load should be pinned");
1859             // Use a cast node to pin clone out of loop
1860             Node* cast = NULL;
1861             for (uint k = 0; k < x->req(); k++) {
1862               Node* in = x->in(k);
1863               if (in != NULL && n_loop->is_member(get_loop(get_ctrl(in)))) {
1864                 const Type* in_t = _igvn.type(in);
1865                 cast = ConstraintCastNode::make_cast_for_type(x_ctrl, in, in_t, ConstraintCastNode::UnconditionalDependency);
1866               }
1867               if (cast != NULL) {
1868                 register_new_node(cast, x_ctrl);
1869                 x->replace_edge(in, cast);
1870                 // Chain of AddP:
1871                 // 2- A CastPP of the base is only added now that both AddP nodes are sunk
1872                 if (x->is_AddP() && k == AddPNode::Base) {
1873                   for (DUIterator_Fast imax, i = x->fast_outs(imax); i < imax; i++) {
1874                     Node* u = x->fast_out(i);
1875                     if (u->is_AddP() && u->in(AddPNode::Base) == n->in(AddPNode::Base)) {
1876                       _igvn.replace_input_of(u, AddPNode::Base, cast);
1877                       assert(u->find_out_with(Op_AddP) == NULL, "more than 2 chained AddP nodes?");
1878                     }
1879                   }
1880                 }
1881                 break;
1882               }
1883             }
1884             assert(cast != NULL, "must have added a cast to pin the node");
1885           }
1886         }
1887         _igvn.remove_dead_node(n);
1888       }
1889       _dom_lca_tags_round = 0;
1890     }
1891   }
1892 }
1893 
1894 // Compute the early control of a node by following its inputs until we reach
1895 // nodes that are pinned. Then compute the LCA of the control of all pinned nodes.
1896 Node* PhaseIdealLoop::compute_early_ctrl(Node* n, Node* n_ctrl) {
1897   Node* early_ctrl = NULL;
1898   ResourceMark rm;
1899   Unique_Node_List wq;
1900   wq.push(n);
1901   for (uint i = 0; i < wq.size(); i++) {
1902     Node* m = wq.at(i);
1903     Node* c = NULL;
1904     if (m->is_CFG()) {
1905       c = m;
1906     } else if (m->pinned()) {
1907       c = m->in(0);
1908     } else {
1909       for (uint j = 0; j < m->req(); j++) {
1910         Node* in = m->in(j);
1911         if (in != NULL) {
1912           wq.push(in);
1913         }
1914       }
1915     }
1916     if (c != NULL) {
1917       assert(is_dominator(c, n_ctrl), "control input must dominate current control");
1918       if (early_ctrl == NULL || is_dominator(early_ctrl, c)) {
1919         early_ctrl = c;
1920       }
1921     }
1922   }
1923   assert(is_dominator(early_ctrl, n_ctrl), "early control must dominate current control");
1924   return early_ctrl;
1925 }
1926 
1927 bool PhaseIdealLoop::ctrl_of_all_uses_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop) {
1928   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1929     Node* u = n->fast_out(i);
1930     if (u->is_Opaque1()) {
1931       return false;  // Found loop limit, bugfix for 4677003
1932     }
1933     // We can't reuse tags in PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal() so make sure calls to
1934     // get_late_ctrl_with_anti_dep() use their own tag
1935     _dom_lca_tags_round++;
1936     assert(_dom_lca_tags_round != 0, "shouldn't wrap around");
1937 
1938     if (u->is_Phi()) {
1939       for (uint j = 1; j < u->req(); ++j) {
1940         if (u->in(j) == n && !ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, u->in(0)->in(j))) {
1941           return false;
1942         }
1943       }
1944     } else {
1945       Node* ctrl = has_ctrl(u) ? get_ctrl(u) : u->in(0);
1946       if (!ctrl_of_use_out_of_loop(n, n_ctrl, n_loop, ctrl)) {
1947         return false;
1948       }
1949     }
1950   }
1951   return true;
1952 }
1953 
1954 bool PhaseIdealLoop::ctrl_of_use_out_of_loop(const Node* n, Node* n_ctrl, IdealLoopTree* n_loop, Node* ctrl) {
1955   if (n->is_Load()) {
1956     ctrl = get_late_ctrl_with_anti_dep(n->as_Load(), n_ctrl, ctrl);
1957   }
1958   IdealLoopTree *u_loop = get_loop(ctrl);
1959   if (u_loop == n_loop) {
1960     return false; // Found loop-varying use
1961   }
1962   if (n_loop->is_member(u_loop)) {
1963     return false; // Found use in inner loop
1964   }
1965   return true;
1966 }
1967 
1968 //------------------------------split_if_with_blocks---------------------------
1969 // Check for aggressive application of 'split-if' optimization,
1970 // using basic block level info.
1971 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1972   Node* root = C->root();
1973   visited.set(root->_idx); // first, mark root as visited
1974   // Do pre-visit work for root
1975   Node* n   = split_if_with_blocks_pre(root);
1976   uint  cnt = n->outcnt();
1977   uint  i   = 0;
1978 
1979   while (true) {
1980     // Visit all children
1981     if (i < cnt) {
1982       Node* use = n->raw_out(i);
1983       ++i;
1984       if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1985         // Now do pre-visit work for this use
1986         use = split_if_with_blocks_pre(use);
1987         nstack.push(n, i); // Save parent and next use's index.
1988         n   = use;         // Process all children of current use.
1989         cnt = use->outcnt();
1990         i   = 0;
1991       }
1992     }
1993     else {
1994       // All of n's children have been processed, complete post-processing.
1995       if (cnt != 0 && !n->is_Con()) {
1996         assert(has_node(n), "no dead nodes");
1997         split_if_with_blocks_post(n);
1998       }
1999       if (must_throttle_split_if()) {
2000         nstack.clear();
2001       }
2002       if (nstack.is_empty()) {
2003         // Finished all nodes on stack.
2004         break;
2005       }
2006       // Get saved parent node and next use's index. Visit the rest of uses.
2007       n   = nstack.node();
2008       cnt = n->outcnt();
2009       i   = nstack.index();
2010       nstack.pop();
2011     }
2012   }
2013 }
2014 
2015 
2016 //=============================================================================
2017 //
2018 //                   C L O N E   A   L O O P   B O D Y
2019 //
2020 
2021 //------------------------------clone_iff--------------------------------------
2022 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2023 // "Nearly" because all Nodes have been cloned from the original in the loop,
2024 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
2025 // through the Phi recursively, and return a Bool.
2026 Node* PhaseIdealLoop::clone_iff(PhiNode* phi) {
2027 
2028   // Convert this Phi into a Phi merging Bools
2029   uint i;
2030   for (i = 1; i < phi->req(); i++) {
2031     Node *b = phi->in(i);
2032     if (b->is_Phi()) {
2033       _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi()));
2034     } else {
2035       assert(b->is_Bool() || b->Opcode() == Op_Opaque4, "");
2036     }
2037   }
2038 
2039   Node* n = phi->in(1);
2040   Node* sample_opaque = NULL;
2041   Node *sample_bool = NULL;
2042   if (n->Opcode() == Op_Opaque4) {
2043     sample_opaque = n;
2044     sample_bool = n->in(1);
2045     assert(sample_bool->is_Bool(), "wrong type");
2046   } else {
2047     sample_bool = n;
2048   }
2049   Node* sample_cmp = sample_bool->in(1);
2050   const Type* t = Type::TOP;
2051   const TypePtr* at = NULL;
2052   if (sample_cmp->is_FlatArrayCheck()) {
2053     // Left input of a FlatArrayCheckNode is memory, set the (adr) type of the phi accordingly
2054     assert(sample_cmp->in(1)->bottom_type() == Type::MEMORY, "unexpected input type");
2055     t = Type::MEMORY;
2056     at = TypeRawPtr::BOTTOM;
2057   }
2058 
2059   // Make Phis to merge the Cmp's inputs.
2060   PhiNode *phi1 = new PhiNode(phi->in(0), t, at);
2061   PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
2062   for (i = 1; i < phi->req(); i++) {
2063     Node *n1 = sample_opaque == NULL ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
2064     Node *n2 = sample_opaque == NULL ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
2065     phi1->set_req(i, n1);
2066     phi2->set_req(i, n2);
2067     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2068     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2069   }
2070   // See if these Phis have been made before.
2071   // Register with optimizer
2072   Node *hit1 = _igvn.hash_find_insert(phi1);
2073   if (hit1) {                   // Hit, toss just made Phi
2074     _igvn.remove_dead_node(phi1); // Remove new phi
2075     assert(hit1->is_Phi(), "" );
2076     phi1 = (PhiNode*)hit1;      // Use existing phi
2077   } else {                      // Miss
2078     _igvn.register_new_node_with_optimizer(phi1);
2079   }
2080   Node *hit2 = _igvn.hash_find_insert(phi2);
2081   if (hit2) {                   // Hit, toss just made Phi
2082     _igvn.remove_dead_node(phi2); // Remove new phi
2083     assert(hit2->is_Phi(), "" );
2084     phi2 = (PhiNode*)hit2;      // Use existing phi
2085   } else {                      // Miss
2086     _igvn.register_new_node_with_optimizer(phi2);
2087   }
2088   // Register Phis with loop/block info
2089   set_ctrl(phi1, phi->in(0));
2090   set_ctrl(phi2, phi->in(0));
2091   // Make a new Cmp
2092   Node *cmp = sample_cmp->clone();
2093   cmp->set_req(1, phi1);
2094   cmp->set_req(2, phi2);
2095   _igvn.register_new_node_with_optimizer(cmp);
2096   set_ctrl(cmp, phi->in(0));
2097 
2098   // Make a new Bool
2099   Node *b = sample_bool->clone();
2100   b->set_req(1,cmp);
2101   _igvn.register_new_node_with_optimizer(b);
2102   set_ctrl(b, phi->in(0));
2103 
2104   if (sample_opaque != NULL) {
2105     Node* opaque = sample_opaque->clone();
2106     opaque->set_req(1, b);
2107     _igvn.register_new_node_with_optimizer(opaque);
2108     set_ctrl(opaque, phi->in(0));
2109     return opaque;
2110   }
2111 
2112   assert(b->is_Bool(), "");
2113   return b;
2114 }
2115 
2116 //------------------------------clone_bool-------------------------------------
2117 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
2118 // "Nearly" because all Nodes have been cloned from the original in the loop,
2119 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
2120 // through the Phi recursively, and return a Bool.
2121 CmpNode*PhaseIdealLoop::clone_bool(PhiNode* phi) {
2122   uint i;
2123   // Convert this Phi into a Phi merging Bools
2124   for( i = 1; i < phi->req(); i++ ) {
2125     Node *b = phi->in(i);
2126     if( b->is_Phi() ) {
2127       _igvn.replace_input_of(phi, i, clone_bool(b->as_Phi()));
2128     } else {
2129       assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
2130     }
2131   }
2132 
2133   Node *sample_cmp = phi->in(1);
2134 
2135   // Make Phis to merge the Cmp's inputs.
2136   PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
2137   PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
2138   for( uint j = 1; j < phi->req(); j++ ) {
2139     Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
2140     Node *n1, *n2;
2141     if( cmp_top->is_Cmp() ) {
2142       n1 = cmp_top->in(1);
2143       n2 = cmp_top->in(2);
2144     } else {
2145       n1 = n2 = cmp_top;
2146     }
2147     phi1->set_req( j, n1 );
2148     phi2->set_req( j, n2 );
2149     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
2150     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
2151   }
2152 
2153   // See if these Phis have been made before.
2154   // Register with optimizer
2155   Node *hit1 = _igvn.hash_find_insert(phi1);
2156   if( hit1 ) {                  // Hit, toss just made Phi
2157     _igvn.remove_dead_node(phi1); // Remove new phi
2158     assert( hit1->is_Phi(), "" );
2159     phi1 = (PhiNode*)hit1;      // Use existing phi
2160   } else {                      // Miss
2161     _igvn.register_new_node_with_optimizer(phi1);
2162   }
2163   Node *hit2 = _igvn.hash_find_insert(phi2);
2164   if( hit2 ) {                  // Hit, toss just made Phi
2165     _igvn.remove_dead_node(phi2); // Remove new phi
2166     assert( hit2->is_Phi(), "" );
2167     phi2 = (PhiNode*)hit2;      // Use existing phi
2168   } else {                      // Miss
2169     _igvn.register_new_node_with_optimizer(phi2);
2170   }
2171   // Register Phis with loop/block info
2172   set_ctrl(phi1, phi->in(0));
2173   set_ctrl(phi2, phi->in(0));
2174   // Make a new Cmp
2175   Node *cmp = sample_cmp->clone();
2176   cmp->set_req( 1, phi1 );
2177   cmp->set_req( 2, phi2 );
2178   _igvn.register_new_node_with_optimizer(cmp);
2179   set_ctrl(cmp, phi->in(0));
2180 
2181   assert( cmp->is_Cmp(), "" );
2182   return (CmpNode*)cmp;
2183 }
2184 
2185 //------------------------------sink_use---------------------------------------
2186 // If 'use' was in the loop-exit block, it now needs to be sunk
2187 // below the post-loop merge point.
2188 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
2189   if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
2190     set_ctrl(use, post_loop);
2191     for (DUIterator j = use->outs(); use->has_out(j); j++)
2192       sink_use(use->out(j), post_loop);
2193   }
2194 }
2195 
2196 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
2197                                                  IdealLoopTree* loop, IdealLoopTree* outer_loop,
2198                                                  Node_List*& split_if_set, Node_List*& split_bool_set,
2199                                                  Node_List*& split_cex_set, Node_List& worklist,
2200                                                  uint new_counter, CloneLoopMode mode) {
2201   Node* nnn = old_new[old->_idx];
2202   // Copy uses to a worklist, so I can munge the def-use info
2203   // with impunity.
2204   for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2205     worklist.push(old->fast_out(j));
2206 
2207   while( worklist.size() ) {
2208     Node *use = worklist.pop();
2209     if (!has_node(use))  continue; // Ignore dead nodes
2210     if (use->in(0) == C->top())  continue;
2211     IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2212     // Check for data-use outside of loop - at least one of OLD or USE
2213     // must not be a CFG node.
2214 #ifdef ASSERT
2215     if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == NULL) {
2216       Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
2217       assert(mode != IgnoreStripMined, "incorrect cloning mode");
2218       assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
2219     }
2220 #endif
2221     if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
2222 
2223       // If the Data use is an IF, that means we have an IF outside of the
2224       // loop that is switching on a condition that is set inside of the
2225       // loop.  Happens if people set a loop-exit flag; then test the flag
2226       // in the loop to break the loop, then test is again outside of the
2227       // loop to determine which way the loop exited.
2228       // Loop predicate If node connects to Bool node through Opaque1 node.
2229       //
2230       // If the use is an AllocateArray through its ValidLengthTest input,
2231       // make sure the Bool/Cmp input is cloned down to avoid a Phi between
2232       // the AllocateArray node and its ValidLengthTest input that could cause
2233       // split if to break.
2234       if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use) || use->Opcode() == Op_Opaque4 ||
2235           (use->Opcode() == Op_AllocateArray && use->in(AllocateNode::ValidLengthTest) == old)) {
2236         // Since this code is highly unlikely, we lazily build the worklist
2237         // of such Nodes to go split.
2238         if (!split_if_set) {
2239           split_if_set = new Node_List();
2240         }
2241         split_if_set->push(use);
2242       }
2243       if (use->is_Bool()) {
2244         if (!split_bool_set) {
2245           split_bool_set = new Node_List();
2246         }
2247         split_bool_set->push(use);
2248       }
2249       if (use->Opcode() == Op_CreateEx) {
2250         if (!split_cex_set) {
2251           split_cex_set = new Node_List();
2252         }
2253         split_cex_set->push(use);
2254       }
2255 
2256 
2257       // Get "block" use is in
2258       uint idx = 0;
2259       while( use->in(idx) != old ) idx++;
2260       Node *prev = use->is_CFG() ? use : get_ctrl(use);
2261       assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
2262       Node *cfg = prev->_idx >= new_counter
2263         ? prev->in(2)
2264         : idom(prev);
2265       if( use->is_Phi() )     // Phi use is in prior block
2266         cfg = prev->in(idx);  // NOT in block of Phi itself
2267       if (cfg->is_top()) {    // Use is dead?
2268         _igvn.replace_input_of(use, idx, C->top());
2269         continue;
2270       }
2271 
2272       // If use is referenced through control edge... (idx == 0)
2273       if (mode == IgnoreStripMined && idx == 0) {
2274         LoopNode *head = loop->_head->as_Loop();
2275         if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
2276           // That node is outside the inner loop, leave it outside the
2277           // outer loop as well to not confuse verification code.
2278           assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
2279           _igvn.replace_input_of(use, 0, head->outer_loop_exit());
2280           continue;
2281         }
2282       }
2283 
2284       while(!outer_loop->is_member(get_loop(cfg))) {
2285         prev = cfg;
2286         cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
2287       }
2288       // If the use occurs after merging several exits from the loop, then
2289       // old value must have dominated all those exits.  Since the same old
2290       // value was used on all those exits we did not need a Phi at this
2291       // merge point.  NOW we do need a Phi here.  Each loop exit value
2292       // is now merged with the peeled body exit; each exit gets its own
2293       // private Phi and those Phis need to be merged here.
2294       Node *phi;
2295       if( prev->is_Region() ) {
2296         if( idx == 0 ) {      // Updating control edge?
2297           phi = prev;         // Just use existing control
2298         } else {              // Else need a new Phi
2299           phi = PhiNode::make( prev, old );
2300           // Now recursively fix up the new uses of old!
2301           for( uint i = 1; i < prev->req(); i++ ) {
2302             worklist.push(phi); // Onto worklist once for each 'old' input
2303           }
2304         }
2305       } else {
2306         // Get new RegionNode merging old and new loop exits
2307         prev = old_new[prev->_idx];
2308         assert( prev, "just made this in step 7" );
2309         if( idx == 0) {      // Updating control edge?
2310           phi = prev;         // Just use existing control
2311         } else {              // Else need a new Phi
2312           // Make a new Phi merging data values properly
2313           phi = PhiNode::make( prev, old );
2314           phi->set_req( 1, nnn );
2315         }
2316       }
2317       // If inserting a new Phi, check for prior hits
2318       if( idx != 0 ) {
2319         Node *hit = _igvn.hash_find_insert(phi);
2320         if( hit == NULL ) {
2321           _igvn.register_new_node_with_optimizer(phi); // Register new phi
2322         } else {                                      // or
2323           // Remove the new phi from the graph and use the hit
2324           _igvn.remove_dead_node(phi);
2325           phi = hit;                                  // Use existing phi
2326         }
2327         set_ctrl(phi, prev);
2328       }
2329       // Make 'use' use the Phi instead of the old loop body exit value
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       // If 'use' was in the loop-exit block, it now needs to be sunk
2342       // below the post-loop merge point.
2343       sink_use( use, prev );
2344     }
2345   }
2346 }
2347 
2348 static void collect_nodes_in_outer_loop_not_reachable_from_sfpt(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
2349                                                                 const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
2350                                                                 bool check_old_new) {
2351   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2352     Node* u = n->fast_out(j);
2353     assert(check_old_new || old_new[u->_idx] == NULL, "shouldn't have been cloned");
2354     if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == NULL)) {
2355       Node* c = phase->get_ctrl(u);
2356       IdealLoopTree* u_loop = phase->get_loop(c);
2357       assert(!loop->is_member(u_loop) || !loop->_body.contains(u), "can be in outer loop or out of both loops only");
2358       if (!loop->is_member(u_loop)) {
2359         if (outer_loop->is_member(u_loop)) {
2360           wq.push(u);
2361         } else {
2362           // nodes pinned with control in the outer loop but not referenced from the safepoint must be moved out of
2363           // the outer loop too
2364           Node* u_c = u->in(0);
2365           if (u_c != NULL) {
2366             IdealLoopTree* u_c_loop = phase->get_loop(u_c);
2367             if (outer_loop->is_member(u_c_loop) && !loop->is_member(u_c_loop)) {
2368               wq.push(u);
2369             }
2370           }
2371         }
2372       }
2373     }
2374   }
2375 }
2376 
2377 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
2378                                       IdealLoopTree* outer_loop, int dd, Node_List &old_new,
2379                                       Node_List& extra_data_nodes) {
2380   if (head->is_strip_mined() && mode != IgnoreStripMined) {
2381     CountedLoopNode* cl = head->as_CountedLoop();
2382     Node* l = cl->outer_loop();
2383     Node* tail = cl->outer_loop_tail();
2384     IfNode* le = cl->outer_loop_end();
2385     Node* sfpt = cl->outer_safepoint();
2386     CountedLoopEndNode* cle = cl->loopexit();
2387     CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
2388     CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
2389     Node* cle_out = cle->proj_out(false);
2390 
2391     Node* new_sfpt = NULL;
2392     Node* new_cle_out = cle_out->clone();
2393     old_new.map(cle_out->_idx, new_cle_out);
2394     if (mode == CloneIncludesStripMined) {
2395       // clone outer loop body
2396       Node* new_l = l->clone();
2397       Node* new_tail = tail->clone();
2398       IfNode* new_le = le->clone()->as_If();
2399       new_sfpt = sfpt->clone();
2400 
2401       set_loop(new_l, outer_loop->_parent);
2402       set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
2403       set_loop(new_cle_out, outer_loop->_parent);
2404       set_idom(new_cle_out, new_cle, dd);
2405       set_loop(new_sfpt, outer_loop->_parent);
2406       set_idom(new_sfpt, new_cle_out, dd);
2407       set_loop(new_le, outer_loop->_parent);
2408       set_idom(new_le, new_sfpt, dd);
2409       set_loop(new_tail, outer_loop->_parent);
2410       set_idom(new_tail, new_le, dd);
2411       set_idom(new_cl, new_l, dd);
2412 
2413       old_new.map(l->_idx, new_l);
2414       old_new.map(tail->_idx, new_tail);
2415       old_new.map(le->_idx, new_le);
2416       old_new.map(sfpt->_idx, new_sfpt);
2417 
2418       new_l->set_req(LoopNode::LoopBackControl, new_tail);
2419       new_l->set_req(0, new_l);
2420       new_tail->set_req(0, new_le);
2421       new_le->set_req(0, new_sfpt);
2422       new_sfpt->set_req(0, new_cle_out);
2423       new_cle_out->set_req(0, new_cle);
2424       new_cl->set_req(LoopNode::EntryControl, new_l);
2425 
2426       _igvn.register_new_node_with_optimizer(new_l);
2427       _igvn.register_new_node_with_optimizer(new_tail);
2428       _igvn.register_new_node_with_optimizer(new_le);
2429     } else {
2430       Node *newhead = old_new[loop->_head->_idx];
2431       newhead->as_Loop()->clear_strip_mined();
2432       _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
2433       set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2434     }
2435     // Look at data node that were assigned a control in the outer
2436     // loop: they are kept in the outer loop by the safepoint so start
2437     // from the safepoint node's inputs.
2438     IdealLoopTree* outer_loop = get_loop(l);
2439     Node_Stack stack(2);
2440     stack.push(sfpt, 1);
2441     uint new_counter = C->unique();
2442     while (stack.size() > 0) {
2443       Node* n = stack.node();
2444       uint i = stack.index();
2445       while (i < n->req() &&
2446              (n->in(i) == NULL ||
2447               !has_ctrl(n->in(i)) ||
2448               get_loop(get_ctrl(n->in(i))) != outer_loop ||
2449               (old_new[n->in(i)->_idx] != NULL && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
2450         i++;
2451       }
2452       if (i < n->req()) {
2453         stack.set_index(i+1);
2454         stack.push(n->in(i), 0);
2455       } else {
2456         assert(old_new[n->_idx] == NULL || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
2457         Node* m = n == sfpt ? new_sfpt : n->clone();
2458         if (m != NULL) {
2459           for (uint i = 0; i < n->req(); i++) {
2460             if (m->in(i) != NULL && old_new[m->in(i)->_idx] != NULL) {
2461               m->set_req(i, old_new[m->in(i)->_idx]);
2462             }
2463           }
2464         } else {
2465           assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2466         }
2467         if (n != sfpt) {
2468           extra_data_nodes.push(n);
2469           _igvn.register_new_node_with_optimizer(m);
2470           assert(get_ctrl(n) == cle_out, "what other control?");
2471           set_ctrl(m, new_cle_out);
2472           old_new.map(n->_idx, m);
2473         }
2474         stack.pop();
2475       }
2476     }
2477     if (mode == CloneIncludesStripMined) {
2478       _igvn.register_new_node_with_optimizer(new_sfpt);
2479       _igvn.register_new_node_with_optimizer(new_cle_out);
2480     }
2481     // Some other transformation may have pessimistically assigned some
2482     // data nodes to the outer loop. Set their control so they are out
2483     // of the outer loop.
2484     ResourceMark rm;
2485     Unique_Node_List wq;
2486     for (uint i = 0; i < extra_data_nodes.size(); i++) {
2487       Node* old = extra_data_nodes.at(i);
2488       collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2489     }
2490 
2491     for (uint i = 0; i < loop->_body.size(); i++) {
2492       Node* old = loop->_body.at(i);
2493       collect_nodes_in_outer_loop_not_reachable_from_sfpt(old, loop, outer_loop, old_new, wq, this, true);
2494     }
2495 
2496     Node* inner_out = sfpt->in(0);
2497     if (inner_out->outcnt() > 1) {
2498       collect_nodes_in_outer_loop_not_reachable_from_sfpt(inner_out, loop, outer_loop, old_new, wq, this, true);
2499     }
2500 
2501     Node* new_ctrl = cl->outer_loop_exit();
2502     assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2503     for (uint i = 0; i < wq.size(); i++) {
2504       Node* n = wq.at(i);
2505       set_ctrl(n, new_ctrl);
2506       if (n->in(0) != NULL) {
2507         _igvn.replace_input_of(n, 0, new_ctrl);
2508       }
2509       collect_nodes_in_outer_loop_not_reachable_from_sfpt(n, loop, outer_loop, old_new, wq, this, false);
2510     }
2511   } else {
2512     Node *newhead = old_new[loop->_head->_idx];
2513     set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2514   }
2515 }
2516 
2517 //------------------------------clone_loop-------------------------------------
2518 //
2519 //                   C L O N E   A   L O O P   B O D Y
2520 //
2521 // This is the basic building block of the loop optimizations.  It clones an
2522 // entire loop body.  It makes an old_new loop body mapping; with this mapping
2523 // you can find the new-loop equivalent to an old-loop node.  All new-loop
2524 // nodes are exactly equal to their old-loop counterparts, all edges are the
2525 // same.  All exits from the old-loop now have a RegionNode that merges the
2526 // equivalent new-loop path.  This is true even for the normal "loop-exit"
2527 // condition.  All uses of loop-invariant old-loop values now come from (one
2528 // or more) Phis that merge their new-loop equivalents.
2529 //
2530 // This operation leaves the graph in an illegal state: there are two valid
2531 // control edges coming from the loop pre-header to both loop bodies.  I'll
2532 // definitely have to hack the graph after running this transform.
2533 //
2534 // From this building block I will further edit edges to perform loop peeling
2535 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2536 //
2537 // Parameter side_by_size_idom:
2538 //   When side_by_size_idom is NULL, the dominator tree is constructed for
2539 //      the clone loop to dominate the original.  Used in construction of
2540 //      pre-main-post loop sequence.
2541 //   When nonnull, the clone and original are side-by-side, both are
2542 //      dominated by the side_by_side_idom node.  Used in construction of
2543 //      unswitched loops.
2544 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2545                                 CloneLoopMode mode, Node* side_by_side_idom) {
2546 
2547   LoopNode* head = loop->_head->as_Loop();
2548   head->verify_strip_mined(1);
2549 
2550   if (C->do_vector_loop() && PrintOpto) {
2551     const char* mname = C->method()->name()->as_quoted_ascii();
2552     if (mname != NULL) {
2553       tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2554     }
2555   }
2556 
2557   CloneMap& cm = C->clone_map();
2558   if (C->do_vector_loop()) {
2559     cm.set_clone_idx(cm.max_gen()+1);
2560 #ifndef PRODUCT
2561     if (PrintOpto) {
2562       tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2563       loop->dump_head();
2564     }
2565 #endif
2566   }
2567 
2568   // Step 1: Clone the loop body.  Make the old->new mapping.
2569   clone_loop_body(loop->_body, old_new, &cm);
2570 
2571   IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2572 
2573   // Step 2: Fix the edges in the new body.  If the old input is outside the
2574   // loop use it.  If the old input is INside the loop, use the corresponding
2575   // new node instead.
2576   fix_body_edges(loop->_body, loop, old_new, dd, outer_loop->_parent, false);
2577 
2578   Node_List extra_data_nodes; // data nodes in the outer strip mined loop
2579   clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2580 
2581   // Step 3: Now fix control uses.  Loop varying control uses have already
2582   // been fixed up (as part of all input edges in Step 2).  Loop invariant
2583   // control uses must be either an IfFalse or an IfTrue.  Make a merge
2584   // point to merge the old and new IfFalse/IfTrue nodes; make the use
2585   // refer to this.
2586   Node_List worklist;
2587   uint new_counter = C->unique();
2588   fix_ctrl_uses(loop->_body, loop, old_new, mode, side_by_side_idom, &cm, worklist);
2589 
2590   // Step 4: If loop-invariant use is not control, it must be dominated by a
2591   // loop exit IfFalse/IfTrue.  Find "proper" loop exit.  Make a Region
2592   // there if needed.  Make a Phi there merging old and new used values.
2593   Node_List *split_if_set = NULL;
2594   Node_List *split_bool_set = NULL;
2595   Node_List *split_cex_set = NULL;
2596   fix_data_uses(loop->_body, loop, mode, outer_loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
2597 
2598   for (uint i = 0; i < extra_data_nodes.size(); i++) {
2599     Node* old = extra_data_nodes.at(i);
2600     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2601                                 split_bool_set, split_cex_set, worklist, new_counter,
2602                                 mode);
2603   }
2604 
2605   // Check for IFs that need splitting/cloning.  Happens if an IF outside of
2606   // the loop uses a condition set in the loop.  The original IF probably
2607   // takes control from one or more OLD Regions (which in turn get from NEW
2608   // Regions).  In any case, there will be a set of Phis for each merge point
2609   // from the IF up to where the original BOOL def exists the loop.
2610   finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
2611 
2612 }
2613 
2614 void PhaseIdealLoop::finish_clone_loop(Node_List* split_if_set, Node_List* split_bool_set, Node_List* split_cex_set) {
2615   if (split_if_set) {
2616     while (split_if_set->size()) {
2617       Node *iff = split_if_set->pop();
2618       uint input = iff->Opcode() == Op_AllocateArray ? AllocateNode::ValidLengthTest : 1;
2619       if (iff->in(input)->is_Phi()) {
2620         Node *b = clone_iff(iff->in(input)->as_Phi());
2621         _igvn.replace_input_of(iff, input, b);
2622       }
2623     }
2624   }
2625   if (split_bool_set) {
2626     while (split_bool_set->size()) {
2627       Node *b = split_bool_set->pop();
2628       Node *phi = b->in(1);
2629       assert(phi->is_Phi(), "");
2630       CmpNode *cmp = clone_bool((PhiNode*) phi);
2631       _igvn.replace_input_of(b, 1, cmp);
2632     }
2633   }
2634   if (split_cex_set) {
2635     while (split_cex_set->size()) {
2636       Node *b = split_cex_set->pop();
2637       assert(b->in(0)->is_Region(), "");
2638       assert(b->in(1)->is_Phi(), "");
2639       assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2640       split_up(b, b->in(0), NULL);
2641     }
2642   }
2643 }
2644 
2645 void PhaseIdealLoop::fix_data_uses(Node_List& body, IdealLoopTree* loop, CloneLoopMode mode, IdealLoopTree* outer_loop,
2646                                    uint new_counter, Node_List &old_new, Node_List &worklist, Node_List*& split_if_set,
2647                                    Node_List*& split_bool_set, Node_List*& split_cex_set) {
2648   for(uint i = 0; i < body.size(); i++ ) {
2649     Node* old = body.at(i);
2650     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2651                                 split_bool_set, split_cex_set, worklist, new_counter,
2652                                 mode);
2653   }
2654 }
2655 
2656 void PhaseIdealLoop::fix_ctrl_uses(const Node_List& body, const IdealLoopTree* loop, Node_List &old_new, CloneLoopMode mode,
2657                                    Node* side_by_side_idom, CloneMap* cm, Node_List &worklist) {
2658   LoopNode* head = loop->_head->as_Loop();
2659   for(uint i = 0; i < body.size(); i++ ) {
2660     Node* old = body.at(i);
2661     if( !old->is_CFG() ) continue;
2662 
2663     // Copy uses to a worklist, so I can munge the def-use info
2664     // with impunity.
2665     for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++) {
2666       worklist.push(old->fast_out(j));
2667     }
2668 
2669     while (worklist.size()) {  // Visit all uses
2670       Node *use = worklist.pop();
2671       if (!has_node(use))  continue; // Ignore dead nodes
2672       IdealLoopTree *use_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use );
2673       if (!loop->is_member(use_loop) && use->is_CFG()) {
2674         // Both OLD and USE are CFG nodes here.
2675         assert(use->is_Proj(), "" );
2676         Node* nnn = old_new[old->_idx];
2677 
2678         Node* newuse = NULL;
2679         if (head->is_strip_mined() && mode != IgnoreStripMined) {
2680           CountedLoopNode* cl = head->as_CountedLoop();
2681           CountedLoopEndNode* cle = cl->loopexit();
2682           Node* cle_out = cle->proj_out_or_null(false);
2683           if (use == cle_out) {
2684             IfNode* le = cl->outer_loop_end();
2685             use = le->proj_out(false);
2686             use_loop = get_loop(use);
2687             if (mode == CloneIncludesStripMined) {
2688               nnn = old_new[le->_idx];
2689             } else {
2690               newuse = old_new[cle_out->_idx];
2691             }
2692           }
2693         }
2694         if (newuse == NULL) {
2695           newuse = use->clone();
2696         }
2697 
2698         // Clone the loop exit control projection
2699         if (C->do_vector_loop() && cm != NULL) {
2700           cm->verify_insert_and_clone(use, newuse, cm->clone_idx());
2701         }
2702         newuse->set_req(0,nnn);
2703         _igvn.register_new_node_with_optimizer(newuse);
2704         set_loop(newuse, use_loop);
2705         set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2706 
2707         // We need a Region to merge the exit from the peeled body and the
2708         // exit from the old loop body.
2709         RegionNode *r = new RegionNode(3);
2710         // Map the old use to the new merge point
2711         old_new.map( use->_idx, r );
2712         uint dd_r = MIN2(dom_depth(newuse), dom_depth(use));
2713         assert(dd_r >= dom_depth(dom_lca(newuse, use)), "" );
2714 
2715         // The original user of 'use' uses 'r' instead.
2716         for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2717           Node* useuse = use->last_out(l);
2718           _igvn.rehash_node_delayed(useuse);
2719           uint uses_found = 0;
2720           if (useuse->in(0) == use) {
2721             useuse->set_req(0, r);
2722             uses_found++;
2723             if (useuse->is_CFG()) {
2724               // This is not a dom_depth > dd_r because when new
2725               // control flow is constructed by a loop opt, a node and
2726               // its dominator can end up at the same dom_depth
2727               assert(dom_depth(useuse) >= dd_r, "");
2728               set_idom(useuse, r, dom_depth(useuse));
2729             }
2730           }
2731           for (uint k = 1; k < useuse->req(); k++) {
2732             if( useuse->in(k) == use ) {
2733               useuse->set_req(k, r);
2734               uses_found++;
2735               if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2736                 // This is not a dom_depth > dd_r because when new
2737                 // control flow is constructed by a loop opt, a node
2738                 // and its dominator can end up at the same dom_depth
2739                 assert(dom_depth(useuse) >= dd_r , "");
2740                 set_idom(useuse, r, dom_depth(useuse));
2741               }
2742             }
2743           }
2744           l -= uses_found;    // we deleted 1 or more copies of this edge
2745         }
2746 
2747         // Now finish up 'r'
2748         r->set_req(1, newuse);
2749         r->set_req(2,    use);
2750         _igvn.register_new_node_with_optimizer(r);
2751         set_loop(r, use_loop);
2752         set_idom(r, (side_by_side_idom == NULL) ? newuse->in(0) : side_by_side_idom, dd_r);
2753       } // End of if a loop-exit test
2754     }
2755   }
2756 }
2757 
2758 void PhaseIdealLoop::fix_body_edges(const Node_List &body, IdealLoopTree* loop, const Node_List &old_new, int dd,
2759                                     IdealLoopTree* parent, bool partial) {
2760   for(uint i = 0; i < body.size(); i++ ) {
2761     Node *old = body.at(i);
2762     Node *nnn = old_new[old->_idx];
2763     // Fix CFG/Loop controlling the new node
2764     if (has_ctrl(old)) {
2765       set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2766     } else {
2767       set_loop(nnn, parent);
2768       if (old->outcnt() > 0) {
2769         Node* dom = idom(old);
2770         if (old_new[dom->_idx] != NULL) {
2771           dom = old_new[dom->_idx];
2772           set_idom(nnn, dom, dd );
2773         }
2774       }
2775     }
2776     // Correct edges to the new node
2777     for (uint j = 0; j < nnn->req(); j++) {
2778         Node *n = nnn->in(j);
2779         if (n != NULL) {
2780           IdealLoopTree *old_in_loop = get_loop(has_ctrl(n) ? get_ctrl(n) : n);
2781           if (loop->is_member(old_in_loop)) {
2782             if (old_new[n->_idx] != NULL) {
2783               nnn->set_req(j, old_new[n->_idx]);
2784             } else {
2785               assert(!body.contains(n), "");
2786               assert(partial, "node not cloned");
2787             }
2788           }
2789         }
2790     }
2791     _igvn.hash_find_insert(nnn);
2792   }
2793 }
2794 
2795 void PhaseIdealLoop::clone_loop_body(const Node_List& body, Node_List &old_new, CloneMap* cm) {
2796   for (uint i = 0; i < body.size(); i++) {
2797     Node* old = body.at(i);
2798     Node* nnn = old->clone();
2799     old_new.map(old->_idx, nnn);
2800     if (old->is_reduction()) {
2801       // Reduction flag is not copied by default. Copy it here when cloning the entire loop body.
2802       nnn->add_flag(Node::Flag_is_reduction);
2803     }
2804     if (C->do_vector_loop() && cm != NULL) {
2805       cm->verify_insert_and_clone(old, nnn, cm->clone_idx());
2806     }
2807     _igvn.register_new_node_with_optimizer(nnn);
2808   }
2809 }
2810 
2811 
2812 //---------------------- stride_of_possible_iv -------------------------------------
2813 // Looks for an iff/bool/comp with one operand of the compare
2814 // being a cycle involving an add and a phi,
2815 // with an optional truncation (left-shift followed by a right-shift)
2816 // of the add. Returns zero if not an iv.
2817 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2818   Node* trunc1 = NULL;
2819   Node* trunc2 = NULL;
2820   const TypeInteger* ttype = NULL;
2821   if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
2822     return 0;
2823   }
2824   BoolNode* bl = iff->in(1)->as_Bool();
2825   Node* cmp = bl->in(1);
2826   if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2827     return 0;
2828   }
2829   // Must have an invariant operand
2830   if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2831     return 0;
2832   }
2833   Node* add2 = NULL;
2834   Node* cmp1 = cmp->in(1);
2835   if (cmp1->is_Phi()) {
2836     // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2837     Node* phi = cmp1;
2838     for (uint i = 1; i < phi->req(); i++) {
2839       Node* in = phi->in(i);
2840       Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2841                                 &trunc1, &trunc2, &ttype, T_INT);
2842       if (add && add->in(1) == phi) {
2843         add2 = add->in(2);
2844         break;
2845       }
2846     }
2847   } else {
2848     // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2849     Node* addtrunc = cmp1;
2850     Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2851                                 &trunc1, &trunc2, &ttype, T_INT);
2852     if (add && add->in(1)->is_Phi()) {
2853       Node* phi = add->in(1);
2854       for (uint i = 1; i < phi->req(); i++) {
2855         if (phi->in(i) == addtrunc) {
2856           add2 = add->in(2);
2857           break;
2858         }
2859       }
2860     }
2861   }
2862   if (add2 != NULL) {
2863     const TypeInt* add2t = _igvn.type(add2)->is_int();
2864     if (add2t->is_con()) {
2865       return add2t->get_con();
2866     }
2867   }
2868   return 0;
2869 }
2870 
2871 
2872 //---------------------- stay_in_loop -------------------------------------
2873 // Return the (unique) control output node that's in the loop (if it exists.)
2874 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2875   Node* unique = NULL;
2876   if (!n) return NULL;
2877   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2878     Node* use = n->fast_out(i);
2879     if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2880       if (unique != NULL) {
2881         return NULL;
2882       }
2883       unique = use;
2884     }
2885   }
2886   return unique;
2887 }
2888 
2889 //------------------------------ register_node -------------------------------------
2890 // Utility to register node "n" with PhaseIdealLoop
2891 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
2892   _igvn.register_new_node_with_optimizer(n);
2893   loop->_body.push(n);
2894   if (n->is_CFG()) {
2895     set_loop(n, loop);
2896     set_idom(n, pred, ddepth);
2897   } else {
2898     set_ctrl(n, pred);
2899   }
2900 }
2901 
2902 //------------------------------ proj_clone -------------------------------------
2903 // Utility to create an if-projection
2904 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2905   ProjNode* c = p->clone()->as_Proj();
2906   c->set_req(0, iff);
2907   return c;
2908 }
2909 
2910 //------------------------------ short_circuit_if -------------------------------------
2911 // Force the iff control output to be the live_proj
2912 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2913   guarantee(live_proj != NULL, "null projection");
2914   int proj_con = live_proj->_con;
2915   assert(proj_con == 0 || proj_con == 1, "false or true projection");
2916   Node *con = _igvn.intcon(proj_con);
2917   set_ctrl(con, C->root());
2918   if (iff) {
2919     iff->set_req(1, con);
2920   }
2921   return con;
2922 }
2923 
2924 //------------------------------ insert_if_before_proj -------------------------------------
2925 // Insert a new if before an if projection (* - new node)
2926 //
2927 // before
2928 //           if(test)
2929 //           /     \
2930 //          v       v
2931 //    other-proj   proj (arg)
2932 //
2933 // after
2934 //           if(test)
2935 //           /     \
2936 //          /       v
2937 //         |      * proj-clone
2938 //         v          |
2939 //    other-proj      v
2940 //                * new_if(relop(cmp[IU](left,right)))
2941 //                  /  \
2942 //                 v    v
2943 //         * new-proj  proj
2944 //         (returned)
2945 //
2946 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2947   IfNode* iff = proj->in(0)->as_If();
2948   IdealLoopTree *loop = get_loop(proj);
2949   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2950   int ddepth = dom_depth(proj);
2951 
2952   _igvn.rehash_node_delayed(iff);
2953   _igvn.rehash_node_delayed(proj);
2954 
2955   proj->set_req(0, NULL);  // temporary disconnect
2956   ProjNode* proj2 = proj_clone(proj, iff);
2957   register_node(proj2, loop, iff, ddepth);
2958 
2959   Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2960   register_node(cmp, loop, proj2, ddepth);
2961 
2962   BoolNode* bol = new BoolNode(cmp, relop);
2963   register_node(bol, loop, proj2, ddepth);
2964 
2965   int opcode = iff->Opcode();
2966   assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2967   IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2968     new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
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 != NULL, "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   int ddepth = dom_depth(proj);
3012 
3013   _igvn.rehash_node_delayed(iff);
3014   _igvn.rehash_node_delayed(proj);
3015 
3016   proj->set_req(0, NULL);  // 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(NULL, 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 //------------------------------ insert_cmpi_loop_exit -------------------------------------
3037 // Clone a signed compare loop exit from an unsigned compare and
3038 // insert it before the unsigned cmp on the stay-in-loop path.
3039 // All new nodes inserted in the dominator tree between the original
3040 // if and it's projections.  The original if test is replaced with
3041 // a constant to force the stay-in-loop path.
3042 //
3043 // This is done to make sure that the original if and it's projections
3044 // still dominate the same set of control nodes, that the ctrl() relation
3045 // from data nodes to them is preserved, and that their loop nesting is
3046 // preserved.
3047 //
3048 // before
3049 //          if(i <u limit)    unsigned compare loop exit
3050 //         /       |
3051 //        v        v
3052 //   exit-proj   stay-in-loop-proj
3053 //
3054 // after
3055 //          if(stay-in-loop-const)  original if
3056 //         /       |
3057 //        /        v
3058 //       /  if(i <  limit)    new signed test
3059 //      /  /       |
3060 //     /  /        v
3061 //    /  /  if(i <u limit)    new cloned unsigned test
3062 //   /  /   /      |
3063 //   v  v  v       |
3064 //    region       |
3065 //        |        |
3066 //      dum-if     |
3067 //     /  |        |
3068 // ether  |        |
3069 //        v        v
3070 //   exit-proj   stay-in-loop-proj
3071 //
3072 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
3073   const bool Signed   = true;
3074   const bool Unsigned = false;
3075 
3076   BoolNode* bol = if_cmpu->in(1)->as_Bool();
3077   if (bol->_test._test != BoolTest::lt) return NULL;
3078   CmpNode* cmpu = bol->in(1)->as_Cmp();
3079   if (cmpu->Opcode() != Op_CmpU) return NULL;
3080   int stride = stride_of_possible_iv(if_cmpu);
3081   if (stride == 0) return NULL;
3082 
3083   Node* lp_proj = stay_in_loop(if_cmpu, loop);
3084   guarantee(lp_proj != NULL, "null loop node");
3085 
3086   ProjNode* lp_continue = lp_proj->as_Proj();
3087   ProjNode* lp_exit     = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
3088   if (!lp_exit->is_IfFalse()) {
3089     // The loop exit condition is (i <u limit) ==> (i >= 0 && i < limit).
3090     // We therefore can't add a single exit condition.
3091     return NULL;
3092   }
3093   // The loop exit condition is !(i <u limit) ==> (i < 0 || i >= limit).
3094   // Split out the exit condition (i < 0) for stride < 0 or (i >= limit) for stride > 0.
3095   Node* limit = NULL;
3096   if (stride > 0) {
3097     limit = cmpu->in(2);
3098   } else {
3099     limit = _igvn.makecon(TypeInt::ZERO);
3100     set_ctrl(limit, C->root());
3101   }
3102   // Create a new region on the exit path
3103   RegionNode* reg = insert_region_before_proj(lp_exit);
3104   guarantee(reg != NULL, "null region node");
3105 
3106   // Clone the if-cmpu-true-false using a signed compare
3107   BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
3108   ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
3109   reg->add_req(cmpi_exit);
3110 
3111   // Clone the if-cmpu-true-false
3112   BoolTest::mask rel_u = bol->_test._test;
3113   ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
3114   reg->add_req(cmpu_exit);
3115 
3116   // Force original if to stay in loop.
3117   short_circuit_if(if_cmpu, lp_continue);
3118 
3119   return cmpi_exit->in(0)->as_If();
3120 }
3121 
3122 //------------------------------ remove_cmpi_loop_exit -------------------------------------
3123 // Remove a previously inserted signed compare loop exit.
3124 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
3125   Node* lp_proj = stay_in_loop(if_cmp, loop);
3126   assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
3127          stay_in_loop(lp_proj, loop)->is_If() &&
3128          stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
3129   Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
3130   set_ctrl(con, C->root());
3131   if_cmp->set_req(1, con);
3132 }
3133 
3134 //------------------------------ scheduled_nodelist -------------------------------------
3135 // Create a post order schedule of nodes that are in the
3136 // "member" set.  The list is returned in "sched".
3137 // The first node in "sched" is the loop head, followed by
3138 // nodes which have no inputs in the "member" set, and then
3139 // followed by the nodes that have an immediate input dependence
3140 // on a node in "sched".
3141 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
3142 
3143   assert(member.test(loop->_head->_idx), "loop head must be in member set");
3144   VectorSet visited;
3145   Node_Stack nstack(loop->_body.size());
3146 
3147   Node* n  = loop->_head;  // top of stack is cached in "n"
3148   uint idx = 0;
3149   visited.set(n->_idx);
3150 
3151   // Initially push all with no inputs from within member set
3152   for(uint i = 0; i < loop->_body.size(); i++ ) {
3153     Node *elt = loop->_body.at(i);
3154     if (member.test(elt->_idx)) {
3155       bool found = false;
3156       for (uint j = 0; j < elt->req(); j++) {
3157         Node* def = elt->in(j);
3158         if (def && member.test(def->_idx) && def != elt) {
3159           found = true;
3160           break;
3161         }
3162       }
3163       if (!found && elt != loop->_head) {
3164         nstack.push(n, idx);
3165         n = elt;
3166         assert(!visited.test(n->_idx), "not seen yet");
3167         visited.set(n->_idx);
3168       }
3169     }
3170   }
3171 
3172   // traverse out's that are in the member set
3173   while (true) {
3174     if (idx < n->outcnt()) {
3175       Node* use = n->raw_out(idx);
3176       idx++;
3177       if (!visited.test_set(use->_idx)) {
3178         if (member.test(use->_idx)) {
3179           nstack.push(n, idx);
3180           n = use;
3181           idx = 0;
3182         }
3183       }
3184     } else {
3185       // All outputs processed
3186       sched.push(n);
3187       if (nstack.is_empty()) break;
3188       n   = nstack.node();
3189       idx = nstack.index();
3190       nstack.pop();
3191     }
3192   }
3193 }
3194 
3195 
3196 //------------------------------ has_use_in_set -------------------------------------
3197 // Has a use in the vector set
3198 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
3199   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3200     Node* use = n->fast_out(j);
3201     if (vset.test(use->_idx)) {
3202       return true;
3203     }
3204   }
3205   return false;
3206 }
3207 
3208 
3209 //------------------------------ has_use_internal_to_set -------------------------------------
3210 // Has use internal to the vector set (ie. not in a phi at the loop head)
3211 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
3212   Node* head  = loop->_head;
3213   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3214     Node* use = n->fast_out(j);
3215     if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
3216       return true;
3217     }
3218   }
3219   return false;
3220 }
3221 
3222 
3223 //------------------------------ clone_for_use_outside_loop -------------------------------------
3224 // clone "n" for uses that are outside of loop
3225 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
3226   int cloned = 0;
3227   assert(worklist.size() == 0, "should be empty");
3228   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3229     Node* use = n->fast_out(j);
3230     if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
3231       worklist.push(use);
3232     }
3233   }
3234 
3235   if (C->check_node_count(worklist.size() + NodeLimitFudgeFactor,
3236                           "Too many clones required in clone_for_use_outside_loop in partial peeling")) {
3237     return -1;
3238   }
3239 
3240   while( worklist.size() ) {
3241     Node *use = worklist.pop();
3242     if (!has_node(use) || use->in(0) == C->top()) continue;
3243     uint j;
3244     for (j = 0; j < use->req(); j++) {
3245       if (use->in(j) == n) break;
3246     }
3247     assert(j < use->req(), "must be there");
3248 
3249     // clone "n" and insert it between the inputs of "n" and the use outside the loop
3250     Node* n_clone = n->clone();
3251     _igvn.replace_input_of(use, j, n_clone);
3252     cloned++;
3253     Node* use_c;
3254     if (!use->is_Phi()) {
3255       use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
3256     } else {
3257       // Use in a phi is considered a use in the associated predecessor block
3258       use_c = use->in(0)->in(j);
3259     }
3260     set_ctrl(n_clone, use_c);
3261     assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
3262     get_loop(use_c)->_body.push(n_clone);
3263     _igvn.register_new_node_with_optimizer(n_clone);
3264 #ifndef PRODUCT
3265     if (TracePartialPeeling) {
3266       tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
3267     }
3268 #endif
3269   }
3270   return cloned;
3271 }
3272 
3273 
3274 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
3275 // clone "n" for special uses that are in the not_peeled region.
3276 // If these def-uses occur in separate blocks, the code generator
3277 // marks the method as not compilable.  For example, if a "BoolNode"
3278 // is in a different basic block than the "IfNode" that uses it, then
3279 // the compilation is aborted in the code generator.
3280 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
3281                                                         VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
3282   if (n->is_Phi() || n->is_Load()) {
3283     return;
3284   }
3285   assert(worklist.size() == 0, "should be empty");
3286   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3287     Node* use = n->fast_out(j);
3288     if ( not_peel.test(use->_idx) &&
3289          (use->is_If() || use->is_CMove() || use->is_Bool()) &&
3290          use->in(1) == n)  {
3291       worklist.push(use);
3292     }
3293   }
3294   if (worklist.size() > 0) {
3295     // clone "n" and insert it between inputs of "n" and the use
3296     Node* n_clone = n->clone();
3297     loop->_body.push(n_clone);
3298     _igvn.register_new_node_with_optimizer(n_clone);
3299     set_ctrl(n_clone, get_ctrl(n));
3300     sink_list.push(n_clone);
3301     not_peel.set(n_clone->_idx);
3302 #ifndef PRODUCT
3303     if (TracePartialPeeling) {
3304       tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
3305     }
3306 #endif
3307     while( worklist.size() ) {
3308       Node *use = worklist.pop();
3309       _igvn.rehash_node_delayed(use);
3310       for (uint j = 1; j < use->req(); j++) {
3311         if (use->in(j) == n) {
3312           use->set_req(j, n_clone);
3313         }
3314       }
3315     }
3316   }
3317 }
3318 
3319 
3320 //------------------------------ insert_phi_for_loop -------------------------------------
3321 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
3322 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
3323   Node *phi = PhiNode::make(lp, back_edge_val);
3324   phi->set_req(LoopNode::EntryControl, lp_entry_val);
3325   // Use existing phi if it already exists
3326   Node *hit = _igvn.hash_find_insert(phi);
3327   if( hit == NULL ) {
3328     _igvn.register_new_node_with_optimizer(phi);
3329     set_ctrl(phi, lp);
3330   } else {
3331     // Remove the new phi from the graph and use the hit
3332     _igvn.remove_dead_node(phi);
3333     phi = hit;
3334   }
3335   _igvn.replace_input_of(use, idx, phi);
3336 }
3337 
3338 #ifdef ASSERT
3339 //------------------------------ is_valid_loop_partition -------------------------------------
3340 // Validate the loop partition sets: peel and not_peel
3341 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
3342                                               VectorSet& not_peel ) {
3343   uint i;
3344   // Check that peel_list entries are in the peel set
3345   for (i = 0; i < peel_list.size(); i++) {
3346     if (!peel.test(peel_list.at(i)->_idx)) {
3347       return false;
3348     }
3349   }
3350   // Check at loop members are in one of peel set or not_peel set
3351   for (i = 0; i < loop->_body.size(); i++ ) {
3352     Node *def  = loop->_body.at(i);
3353     uint di = def->_idx;
3354     // Check that peel set elements are in peel_list
3355     if (peel.test(di)) {
3356       if (not_peel.test(di)) {
3357         return false;
3358       }
3359       // Must be in peel_list also
3360       bool found = false;
3361       for (uint j = 0; j < peel_list.size(); j++) {
3362         if (peel_list.at(j)->_idx == di) {
3363           found = true;
3364           break;
3365         }
3366       }
3367       if (!found) {
3368         return false;
3369       }
3370     } else if (not_peel.test(di)) {
3371       if (peel.test(di)) {
3372         return false;
3373       }
3374     } else {
3375       return false;
3376     }
3377   }
3378   return true;
3379 }
3380 
3381 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
3382 // Ensure a use outside of loop is of the right form
3383 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
3384   Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3385   return (use->is_Phi() &&
3386           use_c->is_Region() && use_c->req() == 3 &&
3387           (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
3388            use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
3389            use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
3390           loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
3391 }
3392 
3393 //------------------------------ is_valid_clone_loop_form -------------------------------------
3394 // Ensure that all uses outside of loop are of the right form
3395 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
3396                                                uint orig_exit_idx, uint clone_exit_idx) {
3397   uint len = peel_list.size();
3398   for (uint i = 0; i < len; i++) {
3399     Node *def = peel_list.at(i);
3400 
3401     for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3402       Node *use = def->fast_out(j);
3403       Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
3404       if (!loop->is_member(get_loop(use_c))) {
3405         // use is not in the loop, check for correct structure
3406         if (use->in(0) == def) {
3407           // Okay
3408         } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
3409           return false;
3410         }
3411       }
3412     }
3413   }
3414   return true;
3415 }
3416 #endif
3417 
3418 //------------------------------ partial_peel -------------------------------------
3419 // Partially peel (aka loop rotation) the top portion of a loop (called
3420 // the peel section below) by cloning it and placing one copy just before
3421 // the new loop head and the other copy at the bottom of the new loop.
3422 //
3423 //    before                       after                where it came from
3424 //
3425 //    stmt1                        stmt1
3426 //  loop:                          stmt2                     clone
3427 //    stmt2                        if condA goto exitA       clone
3428 //    if condA goto exitA        new_loop:                   new
3429 //    stmt3                        stmt3                     clone
3430 //    if !condB goto loop          if condB goto exitB       clone
3431 //  exitB:                         stmt2                     orig
3432 //    stmt4                        if !condA goto new_loop   orig
3433 //  exitA:                         goto exitA
3434 //                               exitB:
3435 //                                 stmt4
3436 //                               exitA:
3437 //
3438 // Step 1: find the cut point: an exit test on probable
3439 //         induction variable.
3440 // Step 2: schedule (with cloning) operations in the peel
3441 //         section that can be executed after the cut into
3442 //         the section that is not peeled.  This may need
3443 //         to clone operations into exit blocks.  For
3444 //         instance, a reference to A[i] in the not-peel
3445 //         section and a reference to B[i] in an exit block
3446 //         may cause a left-shift of i by 2 to be placed
3447 //         in the peel block.  This step will clone the left
3448 //         shift into the exit block and sink the left shift
3449 //         from the peel to the not-peel section.
3450 // Step 3: clone the loop, retarget the control, and insert
3451 //         phis for values that are live across the new loop
3452 //         head.  This is very dependent on the graph structure
3453 //         from clone_loop.  It creates region nodes for
3454 //         exit control and associated phi nodes for values
3455 //         flow out of the loop through that exit.  The region
3456 //         node is dominated by the clone's control projection.
3457 //         So the clone's peel section is placed before the
3458 //         new loop head, and the clone's not-peel section is
3459 //         forms the top part of the new loop.  The original
3460 //         peel section forms the tail of the new loop.
3461 // Step 4: update the dominator tree and recompute the
3462 //         dominator depth.
3463 //
3464 //                   orig
3465 //
3466 //                   stmt1
3467 //                     |
3468 //                     v
3469 //               loop predicate
3470 //                     |
3471 //                     v
3472 //                   loop<----+
3473 //                     |      |
3474 //                   stmt2    |
3475 //                     |      |
3476 //                     v      |
3477 //                    ifA     |
3478 //                   / |      |
3479 //                  v  v      |
3480 //               false true   ^  <-- last_peel
3481 //               /     |      |
3482 //              /   ===|==cut |
3483 //             /     stmt3    |  <-- first_not_peel
3484 //            /        |      |
3485 //            |        v      |
3486 //            v       ifB     |
3487 //          exitA:   / \      |
3488 //                  /   \     |
3489 //                 v     v    |
3490 //               false true   |
3491 //               /       \    |
3492 //              /         ----+
3493 //             |
3494 //             v
3495 //           exitB:
3496 //           stmt4
3497 //
3498 //
3499 //            after clone loop
3500 //
3501 //                   stmt1
3502 //                     |
3503 //                     v
3504 //               loop predicate
3505 //                 /       \
3506 //        clone   /         \   orig
3507 //               /           \
3508 //              /             \
3509 //             v               v
3510 //   +---->loop                loop<----+
3511 //   |      |                    |      |
3512 //   |    stmt2                stmt2    |
3513 //   |      |                    |      |
3514 //   |      v                    v      |
3515 //   |      ifA                 ifA     |
3516 //   |      | \                / |      |
3517 //   |      v  v              v  v      |
3518 //   ^    true  false      false true   ^  <-- last_peel
3519 //   |      |   ^   \       /    |      |
3520 //   | cut==|==  \   \     /  ===|==cut |
3521 //   |    stmt3   \   \   /    stmt3    |  <-- first_not_peel
3522 //   |      |    dom   | |       |      |
3523 //   |      v      \  1v v2      v      |
3524 //   |      ifB     regionA     ifB     |
3525 //   |      / \        |       / \      |
3526 //   |     /   \       v      /   \     |
3527 //   |    v     v    exitA:  v     v    |
3528 //   |    true  false      false true   |
3529 //   |    /     ^   \      /       \    |
3530 //   +----       \   \    /         ----+
3531 //               dom  \  /
3532 //                 \  1v v2
3533 //                  regionB
3534 //                     |
3535 //                     v
3536 //                   exitB:
3537 //                   stmt4
3538 //
3539 //
3540 //           after partial peel
3541 //
3542 //                  stmt1
3543 //                     |
3544 //                     v
3545 //               loop predicate
3546 //                 /
3547 //        clone   /             orig
3548 //               /          TOP
3549 //              /             \
3550 //             v               v
3551 //    TOP->loop                loop----+
3552 //          |                    |      |
3553 //        stmt2                stmt2    |
3554 //          |                    |      |
3555 //          v                    v      |
3556 //          ifA                 ifA     |
3557 //          | \                / |      |
3558 //          v  v              v  v      |
3559 //        true  false      false true   |     <-- last_peel
3560 //          |   ^   \       /    +------|---+
3561 //  +->newloop   \   \     /  === ==cut |   |
3562 //  |     stmt3   \   \   /     TOP     |   |
3563 //  |       |    dom   | |      stmt3   |   | <-- first_not_peel
3564 //  |       v      \  1v v2      v      |   |
3565 //  |       ifB     regionA     ifB     ^   v
3566 //  |       / \        |       / \      |   |
3567 //  |      /   \       v      /   \     |   |
3568 //  |     v     v    exitA:  v     v    |   |
3569 //  |     true  false      false true   |   |
3570 //  |     /     ^   \      /       \    |   |
3571 //  |    |       \   \    /         v   |   |
3572 //  |    |       dom  \  /         TOP  |   |
3573 //  |    |         \  1v v2             |   |
3574 //  ^    v          regionB             |   |
3575 //  |    |             |                |   |
3576 //  |    |             v                ^   v
3577 //  |    |           exitB:             |   |
3578 //  |    |           stmt4              |   |
3579 //  |    +------------>-----------------+   |
3580 //  |                                       |
3581 //  +-----------------<---------------------+
3582 //
3583 //
3584 //              final graph
3585 //
3586 //                  stmt1
3587 //                    |
3588 //                    v
3589 //               loop predicate
3590 //                    |
3591 //                    v
3592 //                  stmt2 clone
3593 //                    |
3594 //                    v
3595 //         ........> ifA clone
3596 //         :        / |
3597 //        dom      /  |
3598 //         :      v   v
3599 //         :  false   true
3600 //         :  |       |
3601 //         :  |       v
3602 //         :  |    newloop<-----+
3603 //         :  |        |        |
3604 //         :  |     stmt3 clone |
3605 //         :  |        |        |
3606 //         :  |        v        |
3607 //         :  |       ifB       |
3608 //         :  |      / \        |
3609 //         :  |     v   v       |
3610 //         :  |  false true     |
3611 //         :  |   |     |       |
3612 //         :  |   v    stmt2    |
3613 //         :  | exitB:  |       |
3614 //         :  | stmt4   v       |
3615 //         :  |       ifA orig  |
3616 //         :  |      /  \       |
3617 //         :  |     /    \      |
3618 //         :  |    v     v      |
3619 //         :  |  false  true    |
3620 //         :  |  /        \     |
3621 //         :  v  v         -----+
3622 //          RegionA
3623 //             |
3624 //             v
3625 //           exitA
3626 //
3627 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3628 
3629   assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3630   if (!loop->_head->is_Loop()) {
3631     return false;
3632   }
3633   LoopNode *head = loop->_head->as_Loop();
3634 
3635   if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3636     return false;
3637   }
3638 
3639   // Check for complex exit control
3640   for (uint ii = 0; ii < loop->_body.size(); ii++) {
3641     Node *n = loop->_body.at(ii);
3642     int opc = n->Opcode();
3643     if (n->is_Call()        ||
3644         opc == Op_Catch     ||
3645         opc == Op_CatchProj ||
3646         opc == Op_Jump      ||
3647         opc == Op_JumpProj) {
3648 #ifndef PRODUCT
3649       if (TracePartialPeeling) {
3650         tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3651       }
3652 #endif
3653       return false;
3654     }
3655   }
3656 
3657   int dd = dom_depth(head);
3658 
3659   // Step 1: find cut point
3660 
3661   // Walk up dominators to loop head looking for first loop exit
3662   // which is executed on every path thru loop.
3663   IfNode *peel_if = NULL;
3664   IfNode *peel_if_cmpu = NULL;
3665 
3666   Node *iff = loop->tail();
3667   while (iff != head) {
3668     if (iff->is_If()) {
3669       Node *ctrl = get_ctrl(iff->in(1));
3670       if (ctrl->is_top()) return false; // Dead test on live IF.
3671       // If loop-varying exit-test, check for induction variable
3672       if (loop->is_member(get_loop(ctrl)) &&
3673           loop->is_loop_exit(iff) &&
3674           is_possible_iv_test(iff)) {
3675         Node* cmp = iff->in(1)->in(1);
3676         if (cmp->Opcode() == Op_CmpI) {
3677           peel_if = iff->as_If();
3678         } else {
3679           assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3680           peel_if_cmpu = iff->as_If();
3681         }
3682       }
3683     }
3684     iff = idom(iff);
3685   }
3686 
3687   // Prefer signed compare over unsigned compare.
3688   IfNode* new_peel_if = NULL;
3689   if (peel_if == NULL) {
3690     if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
3691       return false;   // No peel point found
3692     }
3693     new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3694     if (new_peel_if == NULL) {
3695       return false;   // No peel point found
3696     }
3697     peel_if = new_peel_if;
3698   }
3699   Node* last_peel        = stay_in_loop(peel_if, loop);
3700   Node* first_not_peeled = stay_in_loop(last_peel, loop);
3701   if (first_not_peeled == NULL || first_not_peeled == head) {
3702     return false;
3703   }
3704 
3705 #ifndef PRODUCT
3706   if (TraceLoopOpts) {
3707     tty->print("PartialPeel  ");
3708     loop->dump_head();
3709   }
3710 
3711   if (TracePartialPeeling) {
3712     tty->print_cr("before partial peel one iteration");
3713     Node_List wl;
3714     Node* t = head->in(2);
3715     while (true) {
3716       wl.push(t);
3717       if (t == head) break;
3718       t = idom(t);
3719     }
3720     while (wl.size() > 0) {
3721       Node* tt = wl.pop();
3722       tt->dump();
3723       if (tt == last_peel) tty->print_cr("-- cut --");
3724     }
3725   }
3726 #endif
3727   VectorSet peel;
3728   VectorSet not_peel;
3729   Node_List peel_list;
3730   Node_List worklist;
3731   Node_List sink_list;
3732 
3733   uint estimate = loop->est_loop_clone_sz(1);
3734   if (exceeding_node_budget(estimate)) {
3735     return false;
3736   }
3737 
3738   // Set of cfg nodes to peel are those that are executable from
3739   // the head through last_peel.
3740   assert(worklist.size() == 0, "should be empty");
3741   worklist.push(head);
3742   peel.set(head->_idx);
3743   while (worklist.size() > 0) {
3744     Node *n = worklist.pop();
3745     if (n != last_peel) {
3746       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3747         Node* use = n->fast_out(j);
3748         if (use->is_CFG() &&
3749             loop->is_member(get_loop(use)) &&
3750             !peel.test_set(use->_idx)) {
3751           worklist.push(use);
3752         }
3753       }
3754     }
3755   }
3756 
3757   // Set of non-cfg nodes to peel are those that are control
3758   // dependent on the cfg nodes.
3759   for (uint i = 0; i < loop->_body.size(); i++) {
3760     Node *n = loop->_body.at(i);
3761     Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3762     if (peel.test(n_c->_idx)) {
3763       peel.set(n->_idx);
3764     } else {
3765       not_peel.set(n->_idx);
3766     }
3767   }
3768 
3769   // Step 2: move operations from the peeled section down into the
3770   //         not-peeled section
3771 
3772   // Get a post order schedule of nodes in the peel region
3773   // Result in right-most operand.
3774   scheduled_nodelist(loop, peel, peel_list);
3775 
3776   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3777 
3778   // For future check for too many new phis
3779   uint old_phi_cnt = 0;
3780   for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3781     Node* use = head->fast_out(j);
3782     if (use->is_Phi()) old_phi_cnt++;
3783   }
3784 
3785 #ifndef PRODUCT
3786   if (TracePartialPeeling) {
3787     tty->print_cr("\npeeled list");
3788   }
3789 #endif
3790 
3791   // Evacuate nodes in peel region into the not_peeled region if possible
3792   bool too_many_clones = false;
3793   uint new_phi_cnt = 0;
3794   uint cloned_for_outside_use = 0;
3795   for (uint i = 0; i < peel_list.size();) {
3796     Node* n = peel_list.at(i);
3797 #ifndef PRODUCT
3798   if (TracePartialPeeling) n->dump();
3799 #endif
3800     bool incr = true;
3801     if (!n->is_CFG()) {
3802       if (has_use_in_set(n, not_peel)) {
3803         // If not used internal to the peeled region,
3804         // move "n" from peeled to not_peeled region.
3805         if (!has_use_internal_to_set(n, peel, loop)) {
3806           // if not pinned and not a load (which maybe anti-dependent on a store)
3807           // and not a CMove (Matcher expects only bool->cmove).
3808           if (n->in(0) == NULL && !n->is_Load() && !n->is_CMove()) {
3809             int new_clones = clone_for_use_outside_loop(loop, n, worklist);
3810             if (new_clones == -1) {
3811               too_many_clones = true;
3812               break;
3813             }
3814             cloned_for_outside_use += new_clones;
3815             sink_list.push(n);
3816             peel.remove(n->_idx);
3817             not_peel.set(n->_idx);
3818             peel_list.remove(i);
3819             incr = false;
3820 #ifndef PRODUCT
3821             if (TracePartialPeeling) {
3822               tty->print_cr("sink to not_peeled region: %d newbb: %d",
3823                             n->_idx, get_ctrl(n)->_idx);
3824             }
3825 #endif
3826           }
3827         } else {
3828           // Otherwise check for special def-use cases that span
3829           // the peel/not_peel boundary such as bool->if
3830           clone_for_special_use_inside_loop(loop, n, not_peel, sink_list, worklist);
3831           new_phi_cnt++;
3832         }
3833       }
3834     }
3835     if (incr) i++;
3836   }
3837 
3838   estimate += cloned_for_outside_use + new_phi_cnt;
3839   bool exceed_node_budget = !may_require_nodes(estimate);
3840   bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;
3841 
3842   if (too_many_clones || exceed_node_budget || exceed_phi_limit) {
3843 #ifndef PRODUCT
3844     if (TracePartialPeeling && exceed_phi_limit) {
3845       tty->print_cr("\nToo many new phis: %d  old %d new cmpi: %c",
3846                     new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
3847     }
3848 #endif
3849     if (new_peel_if != NULL) {
3850       remove_cmpi_loop_exit(new_peel_if, loop);
3851     }
3852     // Inhibit more partial peeling on this loop
3853     assert(!head->is_partial_peel_loop(), "not partial peeled");
3854     head->mark_partial_peel_failed();
3855     if (cloned_for_outside_use > 0) {
3856       // Terminate this round of loop opts because
3857       // the graph outside this loop was changed.
3858       C->set_major_progress();
3859       return true;
3860     }
3861     return false;
3862   }
3863 
3864   // Step 3: clone loop, retarget control, and insert new phis
3865 
3866   // Create new loop head for new phis and to hang
3867   // the nodes being moved (sinked) from the peel region.
3868   LoopNode* new_head = new LoopNode(last_peel, last_peel);
3869   new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3870   _igvn.register_new_node_with_optimizer(new_head);
3871   assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3872   _igvn.replace_input_of(first_not_peeled, 0, new_head);
3873   set_loop(new_head, loop);
3874   loop->_body.push(new_head);
3875   not_peel.set(new_head->_idx);
3876   set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3877   set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
3878 
3879   while (sink_list.size() > 0) {
3880     Node* n = sink_list.pop();
3881     set_ctrl(n, new_head);
3882   }
3883 
3884   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3885 
3886   clone_loop(loop, old_new, dd, IgnoreStripMined);
3887 
3888   const uint clone_exit_idx = 1;
3889   const uint orig_exit_idx  = 2;
3890   assert(is_valid_clone_loop_form(loop, peel_list, orig_exit_idx, clone_exit_idx), "bad clone loop");
3891 
3892   Node* head_clone             = old_new[head->_idx];
3893   LoopNode* new_head_clone     = old_new[new_head->_idx]->as_Loop();
3894   Node* orig_tail_clone        = head_clone->in(2);
3895 
3896   // Add phi if "def" node is in peel set and "use" is not
3897 
3898   for (uint i = 0; i < peel_list.size(); i++) {
3899     Node *def  = peel_list.at(i);
3900     if (!def->is_CFG()) {
3901       for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3902         Node *use = def->fast_out(j);
3903         if (has_node(use) && use->in(0) != C->top() &&
3904             (!peel.test(use->_idx) ||
3905              (use->is_Phi() && use->in(0) == head)) ) {
3906           worklist.push(use);
3907         }
3908       }
3909       while( worklist.size() ) {
3910         Node *use = worklist.pop();
3911         for (uint j = 1; j < use->req(); j++) {
3912           Node* n = use->in(j);
3913           if (n == def) {
3914 
3915             // "def" is in peel set, "use" is not in peel set
3916             // or "use" is in the entry boundary (a phi) of the peel set
3917 
3918             Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
3919 
3920             if ( loop->is_member(get_loop( use_c )) ) {
3921               // use is in loop
3922               if (old_new[use->_idx] != NULL) { // null for dead code
3923                 Node* use_clone = old_new[use->_idx];
3924                 _igvn.replace_input_of(use, j, C->top());
3925                 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
3926               }
3927             } else {
3928               assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
3929               // use is not in the loop, check if the live range includes the cut
3930               Node* lp_if = use_c->in(orig_exit_idx)->in(0);
3931               if (not_peel.test(lp_if->_idx)) {
3932                 assert(j == orig_exit_idx, "use from original loop");
3933                 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3934               }
3935             }
3936           }
3937         }
3938       }
3939     }
3940   }
3941 
3942   // Step 3b: retarget control
3943 
3944   // Redirect control to the new loop head if a cloned node in
3945   // the not_peeled region has control that points into the peeled region.
3946   // This necessary because the cloned peeled region will be outside
3947   // the loop.
3948   //                            from    to
3949   //          cloned-peeled    <---+
3950   //    new_head_clone:            |    <--+
3951   //          cloned-not_peeled  in(0)    in(0)
3952   //          orig-peeled
3953 
3954   for (uint i = 0; i < loop->_body.size(); i++) {
3955     Node *n = loop->_body.at(i);
3956     if (!n->is_CFG()           && n->in(0) != NULL        &&
3957         not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3958       Node* n_clone = old_new[n->_idx];
3959       _igvn.replace_input_of(n_clone, 0, new_head_clone);
3960     }
3961   }
3962 
3963   // Backedge of the surviving new_head (the clone) is original last_peel
3964   _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3965 
3966   // Cut first node in original not_peel set
3967   _igvn.rehash_node_delayed(new_head);                     // Multiple edge updates:
3968   new_head->set_req(LoopNode::EntryControl,    C->top());  //   use rehash_node_delayed / set_req instead of
3969   new_head->set_req(LoopNode::LoopBackControl, C->top());  //   multiple replace_input_of calls
3970 
3971   // Copy head_clone back-branch info to original head
3972   // and remove original head's loop entry and
3973   // clone head's back-branch
3974   _igvn.rehash_node_delayed(head); // Multiple edge updates
3975   head->set_req(LoopNode::EntryControl,    head_clone->in(LoopNode::LoopBackControl));
3976   head->set_req(LoopNode::LoopBackControl, C->top());
3977   _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3978 
3979   // Similarly modify the phis
3980   for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3981     Node* use = head->fast_out(k);
3982     if (use->is_Phi() && use->outcnt() > 0) {
3983       Node* use_clone = old_new[use->_idx];
3984       _igvn.rehash_node_delayed(use); // Multiple edge updates
3985       use->set_req(LoopNode::EntryControl,    use_clone->in(LoopNode::LoopBackControl));
3986       use->set_req(LoopNode::LoopBackControl, C->top());
3987       _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3988     }
3989   }
3990 
3991   // Step 4: update dominator tree and dominator depth
3992 
3993   set_idom(head, orig_tail_clone, dd);
3994   recompute_dom_depth();
3995 
3996   // Inhibit more partial peeling on this loop
3997   new_head_clone->set_partial_peel_loop();
3998   C->set_major_progress();
3999   loop->record_for_igvn();
4000 
4001 #ifndef PRODUCT
4002   if (TracePartialPeeling) {
4003     tty->print_cr("\nafter partial peel one iteration");
4004     Node_List wl;
4005     Node* t = last_peel;
4006     while (true) {
4007       wl.push(t);
4008       if (t == head_clone) break;
4009       t = idom(t);
4010     }
4011     while (wl.size() > 0) {
4012       Node* tt = wl.pop();
4013       if (tt == head) tty->print_cr("orig head");
4014       else if (tt == new_head_clone) tty->print_cr("new head");
4015       else if (tt == head_clone) tty->print_cr("clone head");
4016       tt->dump();
4017     }
4018   }
4019 #endif
4020   return true;
4021 }
4022 
4023 // Transform:
4024 //
4025 // loop<-----------------+
4026 //  |                    |
4027 // stmt1 stmt2 .. stmtn  |
4028 //  |     |        |     |
4029 //  \     |       /      |
4030 //    v   v     v        |
4031 //       region          |
4032 //         |             |
4033 //     shared_stmt       |
4034 //         |             |
4035 //         v             |
4036 //         if            |
4037 //         / \           |
4038 //        |   -----------+
4039 //        v
4040 //
4041 // into:
4042 //
4043 //    loop<-------------------+
4044 //     |                      |
4045 //     v                      |
4046 // +->loop                    |
4047 // |   |                      |
4048 // |  stmt1 stmt2 .. stmtn    |
4049 // |   |     |        |       |
4050 // |   |      \       /       |
4051 // |   |       v     v        |
4052 // |   |        region1       |
4053 // |   |           |          |
4054 // |  shared_stmt shared_stmt |
4055 // |   |           |          |
4056 // |   v           v          |
4057 // |   if          if         |
4058 // |   /\          / \        |
4059 // +--   |         |   -------+
4060 //       \         /
4061 //        v       v
4062 //         region2
4063 //
4064 // (region2 is shown to merge mirrored projections of the loop exit
4065 // ifs to make the diagram clearer but they really merge the same
4066 // projection)
4067 //
4068 // Conditions for this transformation to trigger:
4069 // - the path through stmt1 is frequent enough
4070 // - the inner loop will be turned into a counted loop after transformation
4071 bool PhaseIdealLoop::duplicate_loop_backedge(IdealLoopTree *loop, Node_List &old_new) {
4072   if (!DuplicateBackedge) {
4073     return false;
4074   }
4075   assert(!loop->_head->is_CountedLoop() || StressDuplicateBackedge, "Non-counted loop only");
4076   if (!loop->_head->is_Loop()) {
4077     return false;
4078   }
4079 
4080   uint estimate = loop->est_loop_clone_sz(1);
4081   if (exceeding_node_budget(estimate)) {
4082     return false;
4083   }
4084 
4085   LoopNode *head = loop->_head->as_Loop();
4086 
4087   Node* region = NULL;
4088   IfNode* exit_test = NULL;
4089   uint inner;
4090   float f;
4091   if (StressDuplicateBackedge) {
4092     if (head->is_strip_mined()) {
4093       return false;
4094     }
4095     Node* c = head->in(LoopNode::LoopBackControl);
4096 
4097     while (c != head) {
4098       if (c->is_Region()) {
4099         region = c;
4100       }
4101       c = idom(c);
4102     }
4103 
4104     if (region == NULL) {
4105       return false;
4106     }
4107 
4108     inner = 1;
4109   } else {
4110     // Is the shape of the loop that of a counted loop...
4111     Node* back_control = loop_exit_control(head, loop);
4112     if (back_control == NULL) {
4113       return false;
4114     }
4115 
4116     BoolTest::mask bt = BoolTest::illegal;
4117     float cl_prob = 0;
4118     Node* incr = NULL;
4119     Node* limit = NULL;
4120     Node* cmp = loop_exit_test(back_control, loop, incr, limit, bt, cl_prob);
4121     if (cmp == NULL || cmp->Opcode() != Op_CmpI) {
4122       return false;
4123     }
4124 
4125     // With an extra phi for the candidate iv?
4126     // Or the region node is the loop head
4127     if (!incr->is_Phi() || incr->in(0) == head) {
4128       return false;
4129     }
4130 
4131     PathFrequency pf(head, this);
4132     region = incr->in(0);
4133 
4134     // Go over all paths for the extra phi's region and see if that
4135     // path is frequent enough and would match the expected iv shape
4136     // if the extra phi is removed
4137     inner = 0;
4138     for (uint i = 1; i < incr->req(); ++i) {
4139       Node* in = incr->in(i);
4140       Node* trunc1 = NULL;
4141       Node* trunc2 = NULL;
4142       const TypeInteger* iv_trunc_t = NULL;
4143       Node* orig_in = in;
4144       if (!(in = CountedLoopNode::match_incr_with_optional_truncation(in, &trunc1, &trunc2, &iv_trunc_t, T_INT))) {
4145         continue;
4146       }
4147       assert(in->Opcode() == Op_AddI, "wrong increment code");
4148       Node* xphi = NULL;
4149       Node* stride = loop_iv_stride(in, loop, xphi);
4150 
4151       if (stride == NULL) {
4152         continue;
4153       }
4154 
4155       PhiNode* phi = loop_iv_phi(xphi, NULL, head, loop);
4156       if (phi == NULL ||
4157           (trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr) ||
4158           (trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1)) {
4159         return false;
4160       }
4161 
4162       f = pf.to(region->in(i));
4163       if (f > 0.5) {
4164         inner = i;
4165         break;
4166       }
4167     }
4168 
4169     if (inner == 0) {
4170       return false;
4171     }
4172 
4173     exit_test = back_control->in(0)->as_If();
4174   }
4175 
4176   if (idom(region)->is_Catch()) {
4177     return false;
4178   }
4179 
4180   // Collect all control nodes that need to be cloned (shared_stmt in the diagram)
4181   Unique_Node_List wq;
4182   wq.push(head->in(LoopNode::LoopBackControl));
4183   for (uint i = 0; i < wq.size(); i++) {
4184     Node* c = wq.at(i);
4185     assert(get_loop(c) == loop, "not in the right loop?");
4186     if (c->is_Region()) {
4187       if (c != region) {
4188         for (uint j = 1; j < c->req(); ++j) {
4189           wq.push(c->in(j));
4190         }
4191       }
4192     } else {
4193       wq.push(c->in(0));
4194     }
4195     assert(!is_dominator(c, region) || c == region, "shouldn't go above region");
4196   }
4197 
4198   Node* region_dom = idom(region);
4199 
4200   // Can't do the transformation if this would cause a membar pair to
4201   // be split
4202   for (uint i = 0; i < wq.size(); i++) {
4203     Node* c = wq.at(i);
4204     if (c->is_MemBar() && (c->as_MemBar()->trailing_store() || c->as_MemBar()->trailing_load_store())) {
4205       assert(c->as_MemBar()->leading_membar()->trailing_membar() == c, "bad membar pair");
4206       if (!wq.member(c->as_MemBar()->leading_membar())) {
4207         return false;
4208       }
4209     }
4210   }
4211 
4212   // Collect data nodes that need to be clones as well
4213   int dd = dom_depth(head);
4214 
4215   for (uint i = 0; i < loop->_body.size(); ++i) {
4216     Node* n = loop->_body.at(i);
4217     if (has_ctrl(n)) {
4218       Node* c = get_ctrl(n);
4219       if (wq.member(c)) {
4220         wq.push(n);
4221       }
4222     } else {
4223       set_idom(n, idom(n), dd);
4224     }
4225   }
4226 
4227   // clone shared_stmt
4228   clone_loop_body(wq, old_new, NULL);
4229 
4230   Node* region_clone = old_new[region->_idx];
4231   region_clone->set_req(inner, C->top());
4232   set_idom(region, region->in(inner), dd);
4233 
4234   // Prepare the outer loop
4235   Node* outer_head = new LoopNode(head->in(LoopNode::EntryControl), old_new[head->in(LoopNode::LoopBackControl)->_idx]);
4236   register_control(outer_head, loop->_parent, outer_head->in(LoopNode::EntryControl));
4237   _igvn.replace_input_of(head, LoopNode::EntryControl, outer_head);
4238   set_idom(head, outer_head, dd);
4239 
4240   fix_body_edges(wq, loop, old_new, dd, loop->_parent, true);
4241 
4242   // Make one of the shared_stmt copies only reachable from stmt1, the
4243   // other only from stmt2..stmtn.
4244   Node* dom = NULL;
4245   for (uint i = 1; i < region->req(); ++i) {
4246     if (i != inner) {
4247       _igvn.replace_input_of(region, i, C->top());
4248     }
4249     Node* in = region_clone->in(i);
4250     if (in->is_top()) {
4251       continue;
4252     }
4253     if (dom == NULL) {
4254       dom = in;
4255     } else {
4256       dom = dom_lca(dom, in);
4257     }
4258   }
4259 
4260   set_idom(region_clone, dom, dd);
4261 
4262   // Set up the outer loop
4263   for (uint i = 0; i < head->outcnt(); i++) {
4264     Node* u = head->raw_out(i);
4265     if (u->is_Phi()) {
4266       Node* outer_phi = u->clone();
4267       outer_phi->set_req(0, outer_head);
4268       Node* backedge = old_new[u->in(LoopNode::LoopBackControl)->_idx];
4269       if (backedge == NULL) {
4270         backedge = u->in(LoopNode::LoopBackControl);
4271       }
4272       outer_phi->set_req(LoopNode::LoopBackControl, backedge);
4273       register_new_node(outer_phi, outer_head);
4274       _igvn.replace_input_of(u, LoopNode::EntryControl, outer_phi);
4275     }
4276   }
4277 
4278   // create control and data nodes for out of loop uses (including region2)
4279   Node_List worklist;
4280   uint new_counter = C->unique();
4281   fix_ctrl_uses(wq, loop, old_new, ControlAroundStripMined, outer_head, NULL, worklist);
4282 
4283   Node_List *split_if_set = NULL;
4284   Node_List *split_bool_set = NULL;
4285   Node_List *split_cex_set = NULL;
4286   fix_data_uses(wq, loop, ControlAroundStripMined, head->is_strip_mined() ? loop->_parent : loop, new_counter, old_new, worklist, split_if_set, split_bool_set, split_cex_set);
4287 
4288   finish_clone_loop(split_if_set, split_bool_set, split_cex_set);
4289 
4290   if (exit_test != NULL) {
4291     float cnt = exit_test->_fcnt;
4292     if (cnt != COUNT_UNKNOWN) {
4293       exit_test->_fcnt = cnt * f;
4294       old_new[exit_test->_idx]->as_If()->_fcnt = cnt * (1 - f);
4295     }
4296   }
4297 
4298   C->set_major_progress();
4299 
4300   return true;
4301 }