1 /*
   2  * Copyright (c) 1999, 2018, 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/loopnode.hpp"
  37 #include "opto/matcher.hpp"
  38 #include "opto/mulnode.hpp"
  39 #include "opto/movenode.hpp"
  40 #include "opto/opaquenode.hpp"
  41 #include "opto/rootnode.hpp"
  42 #include "opto/subnode.hpp"
  43 #include "utilities/macros.hpp"
  44 #if INCLUDE_ZGC
  45 #include "gc/z/c2/zBarrierSetC2.hpp"
  46 #endif
  47 
  48 //=============================================================================
  49 //------------------------------split_thru_phi---------------------------------
  50 // Split Node 'n' through merge point if there is enough win.
  51 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
  52   if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
  53     // ConvI2L may have type information on it which is unsafe to push up
  54     // so disable this for now
  55     return NULL;
  56   }
  57 
  58   // Splitting range check CastIIs through a loop induction Phi can
  59   // cause new Phis to be created that are left unrelated to the loop
  60   // induction Phi and prevent optimizations (vectorization)
  61   if (n->Opcode() == Op_CastII && n->as_CastII()->has_range_check() &&
  62       region->is_CountedLoop() && n->in(1) == region->as_CountedLoop()->phi()) {
  63     return NULL;
  64   }
  65 
  66   int wins = 0;
  67   assert(!n->is_CFG(), "");
  68   assert(region->is_Region(), "");
  69 
  70   const Type* type = n->bottom_type();
  71   const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
  72   Node *phi;
  73   if (t_oop != NULL && t_oop->is_known_instance_field()) {
  74     int iid    = t_oop->instance_id();
  75     int index  = C->get_alias_index(t_oop);
  76     int offset = t_oop->offset();
  77     phi = new PhiNode(region, type, NULL, iid, index, offset);
  78   } else {
  79     phi = PhiNode::make_blank(region, n);
  80   }
  81   uint old_unique = C->unique();
  82   for (uint i = 1; i < region->req(); i++) {
  83     Node *x;
  84     Node* the_clone = NULL;
  85     if (region->in(i) == C->top()) {
  86       x = C->top();             // Dead path?  Use a dead data op
  87     } else {
  88       x = n->clone();           // Else clone up the data op
  89       the_clone = x;            // Remember for possible deletion.
  90       // Alter data node to use pre-phi inputs
  91       if (n->in(0) == region)
  92         x->set_req( 0, region->in(i) );
  93       for (uint j = 1; j < n->req(); j++) {
  94         Node *in = n->in(j);
  95         if (in->is_Phi() && in->in(0) == region)
  96           x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
  97       }
  98     }
  99     // Check for a 'win' on some paths
 100     const Type *t = x->Value(&_igvn);
 101 
 102     bool singleton = t->singleton();
 103 
 104     // A TOP singleton indicates that there are no possible values incoming
 105     // along a particular edge. In most cases, this is OK, and the Phi will
 106     // be eliminated later in an Ideal call. However, we can't allow this to
 107     // happen if the singleton occurs on loop entry, as the elimination of
 108     // the PhiNode may cause the resulting node to migrate back to a previous
 109     // loop iteration.
 110     if (singleton && t == Type::TOP) {
 111       // Is_Loop() == false does not confirm the absence of a loop (e.g., an
 112       // irreducible loop may not be indicated by an affirmative is_Loop());
 113       // therefore, the only top we can split thru a phi is on a backedge of
 114       // a loop.
 115       singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
 116     }
 117 
 118     if (singleton) {
 119       wins++;
 120       x = ((PhaseGVN&)_igvn).makecon(t);
 121     } else {
 122       // We now call Identity to try to simplify the cloned node.
 123       // Note that some Identity methods call phase->type(this).
 124       // Make sure that the type array is big enough for
 125       // our new node, even though we may throw the node away.
 126       // (Note: This tweaking with igvn only works because x is a new node.)
 127       _igvn.set_type(x, t);
 128       // If x is a TypeNode, capture any more-precise type permanently into Node
 129       // otherwise it will be not updated during igvn->transform since
 130       // igvn->type(x) is set to x->Value() already.
 131       x->raise_bottom_type(t);
 132       Node *y = _igvn.apply_identity(x);
 133       if (y != x) {
 134         wins++;
 135         x = y;
 136       } else {
 137         y = _igvn.hash_find(x);
 138         if (y) {
 139           wins++;
 140           x = y;
 141         } else {
 142           // Else x is a new node we are keeping
 143           // We do not need register_new_node_with_optimizer
 144           // because set_type has already been called.
 145           _igvn._worklist.push(x);
 146         }
 147       }
 148     }
 149     if (x != the_clone && the_clone != NULL)
 150       _igvn.remove_dead_node(the_clone);
 151     phi->set_req( i, x );
 152   }
 153   // Too few wins?
 154   if (wins <= policy) {
 155     _igvn.remove_dead_node(phi);
 156     return NULL;
 157   }
 158 
 159   // Record Phi
 160   register_new_node( phi, region );
 161 
 162   for (uint i2 = 1; i2 < phi->req(); i2++) {
 163     Node *x = phi->in(i2);
 164     // If we commoned up the cloned 'x' with another existing Node,
 165     // the existing Node picks up a new use.  We need to make the
 166     // existing Node occur higher up so it dominates its uses.
 167     Node *old_ctrl;
 168     IdealLoopTree *old_loop;
 169 
 170     if (x->is_Con()) {
 171       // Constant's control is always root.
 172       set_ctrl(x, C->root());
 173       continue;
 174     }
 175     // The occasional new node
 176     if (x->_idx >= old_unique) {     // Found a new, unplaced node?
 177       old_ctrl = NULL;
 178       old_loop = NULL;               // Not in any prior loop
 179     } else {
 180       old_ctrl = get_ctrl(x);
 181       old_loop = get_loop(old_ctrl); // Get prior loop
 182     }
 183     // New late point must dominate new use
 184     Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
 185     if (new_ctrl == old_ctrl) // Nothing is changed
 186       continue;
 187 
 188     IdealLoopTree *new_loop = get_loop(new_ctrl);
 189 
 190     // Don't move x into a loop if its uses are
 191     // outside of loop. Otherwise x will be cloned
 192     // for each use outside of this loop.
 193     IdealLoopTree *use_loop = get_loop(region);
 194     if (!new_loop->is_member(use_loop) &&
 195         (old_loop == NULL || !new_loop->is_member(old_loop))) {
 196       // Take early control, later control will be recalculated
 197       // during next iteration of loop optimizations.
 198       new_ctrl = get_early_ctrl(x);
 199       new_loop = get_loop(new_ctrl);
 200     }
 201     // Set new location
 202     set_ctrl(x, new_ctrl);
 203     // If changing loop bodies, see if we need to collect into new body
 204     if (old_loop != new_loop) {
 205       if (old_loop && !old_loop->_child)
 206         old_loop->_body.yank(x);
 207       if (!new_loop->_child)
 208         new_loop->_body.push(x);  // Collect body info
 209     }
 210   }
 211 
 212   return phi;
 213 }
 214 
 215 //------------------------------dominated_by------------------------------------
 216 // Replace the dominated test with an obvious true or false.  Place it on the
 217 // IGVN worklist for later cleanup.  Move control-dependent data Nodes on the
 218 // live path up to the dominating control.
 219 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
 220   if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
 221 
 222   // prevdom is the dominating projection of the dominating test.
 223   assert( iff->is_If(), "" );
 224   assert(iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd || iff->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
 225   int pop = prevdom->Opcode();
 226   assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
 227   if (flip) {
 228     if (pop == Op_IfTrue)
 229       pop = Op_IfFalse;
 230     else
 231       pop = Op_IfTrue;
 232   }
 233   // 'con' is set to true or false to kill the dominated test.
 234   Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
 235   set_ctrl(con, C->root()); // Constant gets a new use
 236   // Hack the dominated test
 237   _igvn.replace_input_of(iff, 1, con);
 238 
 239   // If I dont have a reachable TRUE and FALSE path following the IfNode then
 240   // I can assume this path reaches an infinite loop.  In this case it's not
 241   // important to optimize the data Nodes - either the whole compilation will
 242   // be tossed or this path (and all data Nodes) will go dead.
 243   if (iff->outcnt() != 2) return;
 244 
 245   // Make control-dependent data Nodes on the live path (path that will remain
 246   // once the dominated IF is removed) become control-dependent on the
 247   // dominating projection.
 248   Node* dp = iff->as_If()->proj_out_or_null(pop == Op_IfTrue);
 249 
 250   // Loop predicates may have depending checks which should not
 251   // be skipped. For example, range check predicate has two checks
 252   // for lower and upper bounds.
 253   if (dp == NULL)
 254     return;
 255 
 256   ProjNode* dp_proj  = dp->as_Proj();
 257   ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
 258   if (exclude_loop_predicate &&
 259       (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
 260        unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != NULL ||
 261        unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
 262     // If this is a range check (IfNode::is_range_check), do not
 263     // reorder because Compile::allow_range_check_smearing might have
 264     // changed the check.
 265     return; // Let IGVN transformation change control dependence.
 266   }
 267 
 268   IdealLoopTree *old_loop = get_loop(dp);
 269 
 270   for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
 271     Node* cd = dp->fast_out(i); // Control-dependent node
 272     if (cd->depends_only_on_test()) {
 273       assert(cd->in(0) == dp, "");
 274       _igvn.replace_input_of(cd, 0, prevdom);
 275       set_early_ctrl(cd);
 276       IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
 277       if (old_loop != new_loop) {
 278         if (!old_loop->_child) old_loop->_body.yank(cd);
 279         if (!new_loop->_child) new_loop->_body.push(cd);
 280       }
 281       --i;
 282       --imax;
 283     }
 284   }
 285 }
 286 
 287 //------------------------------has_local_phi_input----------------------------
 288 // Return TRUE if 'n' has Phi inputs from its local block and no other
 289 // block-local inputs (all non-local-phi inputs come from earlier blocks)
 290 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
 291   Node *n_ctrl = get_ctrl(n);
 292   // See if some inputs come from a Phi in this block, or from before
 293   // this block.
 294   uint i;
 295   for( i = 1; i < n->req(); i++ ) {
 296     Node *phi = n->in(i);
 297     if( phi->is_Phi() && phi->in(0) == n_ctrl )
 298       break;
 299   }
 300   if( i >= n->req() )
 301     return NULL;                // No Phi inputs; nowhere to clone thru
 302 
 303   // Check for inputs created between 'n' and the Phi input.  These
 304   // must split as well; they have already been given the chance
 305   // (courtesy of a post-order visit) and since they did not we must
 306   // recover the 'cost' of splitting them by being very profitable
 307   // when splitting 'n'.  Since this is unlikely we simply give up.
 308   for( i = 1; i < n->req(); i++ ) {
 309     Node *m = n->in(i);
 310     if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
 311       // We allow the special case of AddP's with no local inputs.
 312       // This allows us to split-up address expressions.
 313       if (m->is_AddP() &&
 314           get_ctrl(m->in(2)) != n_ctrl &&
 315           get_ctrl(m->in(3)) != n_ctrl) {
 316         // Move the AddP up to dominating point
 317         Node* c = find_non_split_ctrl(idom(n_ctrl));
 318         if (c->is_OuterStripMinedLoop()) {
 319           c->as_Loop()->verify_strip_mined(1);
 320           c = c->in(LoopNode::EntryControl);
 321         }
 322         set_ctrl_and_loop(m, c);
 323         continue;
 324       }
 325       return NULL;
 326     }
 327     assert(m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
 328   }
 329 
 330   return n_ctrl;
 331 }
 332 
 333 //------------------------------remix_address_expressions----------------------
 334 // Rework addressing expressions to get the most loop-invariant stuff
 335 // moved out.  We'd like to do all associative operators, but it's especially
 336 // important (common) to do address expressions.
 337 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
 338   if (!has_ctrl(n))  return NULL;
 339   Node *n_ctrl = get_ctrl(n);
 340   IdealLoopTree *n_loop = get_loop(n_ctrl);
 341 
 342   // See if 'n' mixes loop-varying and loop-invariant inputs and
 343   // itself is loop-varying.
 344 
 345   // Only interested in binary ops (and AddP)
 346   if( n->req() < 3 || n->req() > 4 ) return NULL;
 347 
 348   Node *n1_ctrl = get_ctrl(n->in(                    1));
 349   Node *n2_ctrl = get_ctrl(n->in(                    2));
 350   Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
 351   IdealLoopTree *n1_loop = get_loop( n1_ctrl );
 352   IdealLoopTree *n2_loop = get_loop( n2_ctrl );
 353   IdealLoopTree *n3_loop = get_loop( n3_ctrl );
 354 
 355   // Does one of my inputs spin in a tighter loop than self?
 356   if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
 357       (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
 358       (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
 359     return NULL;                // Leave well enough alone
 360 
 361   // Is at least one of my inputs loop-invariant?
 362   if( n1_loop == n_loop &&
 363       n2_loop == n_loop &&
 364       n3_loop == n_loop )
 365     return NULL;                // No loop-invariant inputs
 366 
 367 
 368   int n_op = n->Opcode();
 369 
 370   // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
 371   if( n_op == Op_LShiftI ) {
 372     // Scale is loop invariant
 373     Node *scale = n->in(2);
 374     Node *scale_ctrl = get_ctrl(scale);
 375     IdealLoopTree *scale_loop = get_loop(scale_ctrl );
 376     if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
 377       return NULL;
 378     const TypeInt *scale_t = scale->bottom_type()->isa_int();
 379     if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
 380       return NULL;              // Dont bother with byte/short masking
 381     // Add must vary with loop (else shift would be loop-invariant)
 382     Node *add = n->in(1);
 383     Node *add_ctrl = get_ctrl(add);
 384     IdealLoopTree *add_loop = get_loop(add_ctrl);
 385     //assert( n_loop == add_loop, "" );
 386     if( n_loop != add_loop ) return NULL;  // happens w/ evil ZKM loops
 387 
 388     // Convert I-V into I+ (0-V); same for V-I
 389     if( add->Opcode() == Op_SubI &&
 390         _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
 391       Node *zero = _igvn.intcon(0);
 392       set_ctrl(zero, C->root());
 393       Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
 394       register_new_node( neg, get_ctrl(add->in(2) ) );
 395       add = new AddINode( add->in(1), neg );
 396       register_new_node( add, add_ctrl );
 397     }
 398     if( add->Opcode() != Op_AddI ) return NULL;
 399     // See if one add input is loop invariant
 400     Node *add_var = add->in(1);
 401     Node *add_var_ctrl = get_ctrl(add_var);
 402     IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
 403     Node *add_invar = add->in(2);
 404     Node *add_invar_ctrl = get_ctrl(add_invar);
 405     IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
 406     if( add_var_loop == n_loop ) {
 407     } else if( add_invar_loop == n_loop ) {
 408       // Swap to find the invariant part
 409       add_invar = add_var;
 410       add_invar_ctrl = add_var_ctrl;
 411       add_invar_loop = add_var_loop;
 412       add_var = add->in(2);
 413       Node *add_var_ctrl = get_ctrl(add_var);
 414       IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
 415     } else                      // Else neither input is loop invariant
 416       return NULL;
 417     if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
 418       return NULL;              // No invariant part of the add?
 419 
 420     // Yes!  Reshape address expression!
 421     Node *inv_scale = new LShiftINode( add_invar, scale );
 422     Node *inv_scale_ctrl =
 423       dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
 424       add_invar_ctrl : scale_ctrl;
 425     register_new_node( inv_scale, inv_scale_ctrl );
 426     Node *var_scale = new LShiftINode( add_var, scale );
 427     register_new_node( var_scale, n_ctrl );
 428     Node *var_add = new AddINode( var_scale, inv_scale );
 429     register_new_node( var_add, n_ctrl );
 430     _igvn.replace_node( n, var_add );
 431     return var_add;
 432   }
 433 
 434   // Replace (I+V) with (V+I)
 435   if( n_op == Op_AddI ||
 436       n_op == Op_AddL ||
 437       n_op == Op_AddF ||
 438       n_op == Op_AddD ||
 439       n_op == Op_MulI ||
 440       n_op == Op_MulL ||
 441       n_op == Op_MulF ||
 442       n_op == Op_MulD ) {
 443     if( n2_loop == n_loop ) {
 444       assert( n1_loop != n_loop, "" );
 445       n->swap_edges(1, 2);
 446     }
 447   }
 448 
 449   // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
 450   // but not if I2 is a constant.
 451   if( n_op == Op_AddP ) {
 452     if( n2_loop == n_loop && n3_loop != n_loop ) {
 453       if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
 454         Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
 455         Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
 456         IdealLoopTree *n22loop = get_loop( n22_ctrl );
 457         IdealLoopTree *n23_loop = get_loop( n23_ctrl );
 458         if( n22loop != n_loop && n22loop->is_member(n_loop) &&
 459             n23_loop == n_loop ) {
 460           Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
 461           // Stuff new AddP in the loop preheader
 462           register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
 463           Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
 464           register_new_node( add2, n_ctrl );
 465           _igvn.replace_node( n, add2 );
 466           return add2;
 467         }
 468       }
 469     }
 470 
 471     // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
 472     if (n2_loop != n_loop && n3_loop == n_loop) {
 473       if (n->in(3)->Opcode() == Op_AddX) {
 474         Node *V = n->in(3)->in(1);
 475         Node *I = n->in(3)->in(2);
 476         if (is_member(n_loop,get_ctrl(V))) {
 477         } else {
 478           Node *tmp = V; V = I; I = tmp;
 479         }
 480         if (!is_member(n_loop,get_ctrl(I))) {
 481           Node *add1 = new AddPNode(n->in(1), n->in(2), I);
 482           // Stuff new AddP in the loop preheader
 483           register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
 484           Node *add2 = new AddPNode(n->in(1), add1, V);
 485           register_new_node(add2, n_ctrl);
 486           _igvn.replace_node(n, add2);
 487           return add2;
 488         }
 489       }
 490     }
 491   }
 492 
 493   return NULL;
 494 }
 495 
 496 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
 497 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
 498   assert(n->Opcode() == Op_AddI, "sanity");
 499   Node * nn = NULL;
 500   Node * in1 = n->in(1);
 501   Node * in2 = n->in(2);
 502   if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
 503     IdealLoopTree* loop_n = get_loop(get_ctrl(n));
 504     if (loop_n->_head->as_Loop()->is_valid_counted_loop() &&
 505         Matcher::match_rule_supported(Op_MulAddS2I) &&
 506         Matcher::match_rule_supported(Op_MulAddVS2VI)) {
 507       Node* mul_in1 = in1->in(1);
 508       Node* mul_in2 = in1->in(2);
 509       Node* mul_in3 = in2->in(1);
 510       Node* mul_in4 = in2->in(2);
 511       if (mul_in1->Opcode() == Op_LoadS &&
 512           mul_in2->Opcode() == Op_LoadS &&
 513           mul_in3->Opcode() == Op_LoadS &&
 514           mul_in4->Opcode() == Op_LoadS) {
 515         IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
 516         IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
 517         IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
 518         IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
 519         IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
 520         IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
 521         // All nodes should be in the same counted loop.
 522         if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
 523             loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
 524           Node* adr1 = mul_in1->in(MemNode::Address);
 525           Node* adr2 = mul_in2->in(MemNode::Address);
 526           Node* adr3 = mul_in3->in(MemNode::Address);
 527           Node* adr4 = mul_in4->in(MemNode::Address);
 528           if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
 529             if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
 530                 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
 531               nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
 532               register_new_node(nn, get_ctrl(n));
 533               _igvn.replace_node(n, nn);
 534               return nn;
 535             } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
 536                        (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
 537               nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
 538               register_new_node(nn, get_ctrl(n));
 539               _igvn.replace_node(n, nn);
 540               return nn;
 541             }
 542           }
 543         }
 544       }
 545     }
 546   }
 547   return nn;
 548 }
 549 
 550 //------------------------------conditional_move-------------------------------
 551 // Attempt to replace a Phi with a conditional move.  We have some pretty
 552 // strict profitability requirements.  All Phis at the merge point must
 553 // be converted, so we can remove the control flow.  We need to limit the
 554 // number of c-moves to a small handful.  All code that was in the side-arms
 555 // of the CFG diamond is now speculatively executed.  This code has to be
 556 // "cheap enough".  We are pretty much limited to CFG diamonds that merge
 557 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
 558 Node *PhaseIdealLoop::conditional_move( Node *region ) {
 559 
 560   assert(region->is_Region(), "sanity check");
 561   if (region->req() != 3) return NULL;
 562 
 563   // Check for CFG diamond
 564   Node *lp = region->in(1);
 565   Node *rp = region->in(2);
 566   if (!lp || !rp) return NULL;
 567   Node *lp_c = lp->in(0);
 568   if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
 569   IfNode *iff = lp_c->as_If();
 570 
 571   // Check for ops pinned in an arm of the diamond.
 572   // Can't remove the control flow in this case
 573   if (lp->outcnt() > 1) return NULL;
 574   if (rp->outcnt() > 1) return NULL;
 575 
 576   IdealLoopTree* r_loop = get_loop(region);
 577   assert(r_loop == get_loop(iff), "sanity");
 578   // Always convert to CMOVE if all results are used only outside this loop.
 579   bool used_inside_loop = (r_loop == _ltree_root);
 580 
 581   // Check profitability
 582   int cost = 0;
 583   int phis = 0;
 584   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 585     Node *out = region->fast_out(i);
 586     if (!out->is_Phi()) continue; // Ignore other control edges, etc
 587     phis++;
 588     PhiNode* phi = out->as_Phi();
 589     BasicType bt = phi->type()->basic_type();
 590     switch (bt) {
 591     case T_DOUBLE:
 592     case T_FLOAT:
 593       if (C->use_cmove()) {
 594         continue; //TODO: maybe we want to add some cost
 595       }
 596       cost += Matcher::float_cmove_cost(); // Could be very expensive
 597       break;
 598     case T_LONG: {
 599       cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
 600     }
 601     case T_INT:                 // These all CMOV fine
 602     case T_ADDRESS: {           // (RawPtr)
 603       cost++;
 604       break;
 605     }
 606     case T_NARROWOOP: // Fall through
 607     case T_OBJECT: {            // Base oops are OK, but not derived oops
 608       const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
 609       // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
 610       // CMOVE'd derived pointer?  It's a CMOVE'd derived base.  Thus
 611       // CMOVE'ing a derived pointer requires we also CMOVE the base.  If we
 612       // have a Phi for the base here that we convert to a CMOVE all is well
 613       // and good.  But if the base is dead, we'll not make a CMOVE.  Later
 614       // the allocator will have to produce a base by creating a CMOVE of the
 615       // relevant bases.  This puts the allocator in the business of
 616       // manufacturing expensive instructions, generally a bad plan.
 617       // Just Say No to Conditionally-Moved Derived Pointers.
 618       if (tp && tp->offset() != 0)
 619         return NULL;
 620       cost++;
 621       break;
 622     }
 623     default:
 624       return NULL;              // In particular, can't do memory or I/O
 625     }
 626     // Add in cost any speculative ops
 627     for (uint j = 1; j < region->req(); j++) {
 628       Node *proj = region->in(j);
 629       Node *inp = phi->in(j);
 630       if (get_ctrl(inp) == proj) { // Found local op
 631         cost++;
 632         // Check for a chain of dependent ops; these will all become
 633         // speculative in a CMOV.
 634         for (uint k = 1; k < inp->req(); k++)
 635           if (get_ctrl(inp->in(k)) == proj)
 636             cost += ConditionalMoveLimit; // Too much speculative goo
 637       }
 638     }
 639     // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
 640     // This will likely Split-If, a higher-payoff operation.
 641     for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
 642       Node* use = phi->fast_out(k);
 643       if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
 644         cost += ConditionalMoveLimit;
 645       // Is there a use inside the loop?
 646       // Note: check only basic types since CMoveP is pinned.
 647       if (!used_inside_loop && is_java_primitive(bt)) {
 648         IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
 649         if (r_loop == u_loop || r_loop->is_member(u_loop)) {
 650           used_inside_loop = true;
 651         }
 652       }
 653     }
 654   }//for
 655   Node* bol = iff->in(1);
 656   assert(bol->Opcode() == Op_Bool, "");
 657   int cmp_op = bol->in(1)->Opcode();
 658   // It is expensive to generate flags from a float compare.
 659   // Avoid duplicated float compare.
 660   if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
 661 
 662   float infrequent_prob = PROB_UNLIKELY_MAG(3);
 663   // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
 664   if (used_inside_loop) {
 665     if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
 666 
 667     // BlockLayoutByFrequency optimization moves infrequent branch
 668     // from hot path. No point in CMOV'ing in such case (110 is used
 669     // instead of 100 to take into account not exactness of float value).
 670     if (BlockLayoutByFrequency) {
 671       infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
 672     }
 673   }
 674   // Check for highly predictable branch.  No point in CMOV'ing if
 675   // we are going to predict accurately all the time.
 676   if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
 677     //keep going
 678   } else if (iff->_prob < infrequent_prob ||
 679       iff->_prob > (1.0f - infrequent_prob))
 680     return NULL;
 681 
 682   // --------------
 683   // Now replace all Phis with CMOV's
 684   Node *cmov_ctrl = iff->in(0);
 685   uint flip = (lp->Opcode() == Op_IfTrue);
 686   Node_List wq;
 687   while (1) {
 688     PhiNode* phi = NULL;
 689     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 690       Node *out = region->fast_out(i);
 691       if (out->is_Phi()) {
 692         phi = out->as_Phi();
 693         break;
 694       }
 695     }
 696     if (phi == NULL)  break;
 697     if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
 698     // Move speculative ops
 699     wq.push(phi);
 700     while (wq.size() > 0) {
 701       Node *n = wq.pop();
 702       for (uint j = 1; j < n->req(); j++) {
 703         Node* m = n->in(j);
 704         if (m != NULL && !is_dominator(get_ctrl(m), cmov_ctrl)) {
 705 #ifndef PRODUCT
 706           if (PrintOpto && VerifyLoopOptimizations) {
 707             tty->print("  speculate: ");
 708             m->dump();
 709           }
 710 #endif
 711           set_ctrl(m, cmov_ctrl);
 712           wq.push(m);
 713         }
 714       }
 715     }
 716     Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
 717     register_new_node( cmov, cmov_ctrl );
 718     _igvn.replace_node( phi, cmov );
 719 #ifndef PRODUCT
 720     if (TraceLoopOpts) {
 721       tty->print("CMOV  ");
 722       r_loop->dump_head();
 723       if (Verbose) {
 724         bol->in(1)->dump(1);
 725         cmov->dump(1);
 726       }
 727     }
 728     if (VerifyLoopOptimizations) verify();
 729 #endif
 730   }
 731 
 732   // The useless CFG diamond will fold up later; see the optimization in
 733   // RegionNode::Ideal.
 734   _igvn._worklist.push(region);
 735 
 736   return iff->in(1);
 737 }
 738 
 739 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
 740   for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
 741     Node* u = m->fast_out(i);
 742     if (u->is_CFG()) {
 743       if (u->Opcode() == Op_NeverBranch) {
 744         u = ((NeverBranchNode*)u)->proj_out(0);
 745         enqueue_cfg_uses(u, wq);
 746       } else {
 747         wq.push(u);
 748       }
 749     }
 750   }
 751 }
 752 
 753 // Try moving a store out of a loop, right before the loop
 754 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
 755   // Store has to be first in the loop body
 756   IdealLoopTree *n_loop = get_loop(n_ctrl);
 757   if (n->is_Store() && n_loop != _ltree_root &&
 758       n_loop->is_loop() && n_loop->_head->is_Loop() &&
 759       n->in(0) != NULL) {
 760     Node* address = n->in(MemNode::Address);
 761     Node* value = n->in(MemNode::ValueIn);
 762     Node* mem = n->in(MemNode::Memory);
 763     IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 764     IdealLoopTree* value_loop = get_loop(get_ctrl(value));
 765 
 766     // - address and value must be loop invariant
 767     // - memory must be a memory Phi for the loop
 768     // - Store must be the only store on this memory slice in the
 769     // loop: if there's another store following this one then value
 770     // written at iteration i by the second store could be overwritten
 771     // at iteration i+n by the first store: it's not safe to move the
 772     // first store out of the loop
 773     // - nothing must observe the memory Phi: it guarantees no read
 774     // before the store, we are also guaranteed the store post
 775     // dominates the loop head (ignoring a possible early
 776     // exit). Otherwise there would be extra Phi involved between the
 777     // loop's Phi and the store.
 778     // - there must be no early exit from the loop before the Store
 779     // (such an exit most of the time would be an extra use of the
 780     // memory Phi but sometimes is a bottom memory Phi that takes the
 781     // store as input).
 782 
 783     if (!n_loop->is_member(address_loop) &&
 784         !n_loop->is_member(value_loop) &&
 785         mem->is_Phi() && mem->in(0) == n_loop->_head &&
 786         mem->outcnt() == 1 &&
 787         mem->in(LoopNode::LoopBackControl) == n) {
 788 
 789       assert(n_loop->_tail != NULL, "need a tail");
 790       assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
 791 
 792       // Verify that there's no early exit of the loop before the store.
 793       bool ctrl_ok = false;
 794       {
 795         // Follow control from loop head until n, we exit the loop or
 796         // we reach the tail
 797         ResourceMark rm;
 798         Unique_Node_List wq;
 799         wq.push(n_loop->_head);
 800 
 801         for (uint next = 0; next < wq.size(); ++next) {
 802           Node *m = wq.at(next);
 803           if (m == n->in(0)) {
 804             ctrl_ok = true;
 805             continue;
 806           }
 807           assert(!has_ctrl(m), "should be CFG");
 808           if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
 809             ctrl_ok = false;
 810             break;
 811           }
 812           enqueue_cfg_uses(m, wq);
 813           if (wq.size() > 10) {
 814             ctrl_ok = false;
 815             break;
 816           }
 817         }
 818       }
 819       if (ctrl_ok) {
 820         // move the Store
 821         _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
 822         _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
 823         _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
 824         // Disconnect the phi now. An empty phi can confuse other
 825         // optimizations in this pass of loop opts.
 826         _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
 827         n_loop->_body.yank(mem);
 828 
 829         set_ctrl_and_loop(n, n->in(0));
 830 
 831         return n;
 832       }
 833     }
 834   }
 835   return NULL;
 836 }
 837 
 838 // Try moving a store out of a loop, right after the loop
 839 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
 840   if (n->is_Store() && n->in(0) != NULL) {
 841     Node *n_ctrl = get_ctrl(n);
 842     IdealLoopTree *n_loop = get_loop(n_ctrl);
 843     // Store must be in a loop
 844     if (n_loop != _ltree_root && !n_loop->_irreducible) {
 845       Node* address = n->in(MemNode::Address);
 846       Node* value = n->in(MemNode::ValueIn);
 847       IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 848       // address must be loop invariant
 849       if (!n_loop->is_member(address_loop)) {
 850         // Store must be last on this memory slice in the loop and
 851         // nothing in the loop must observe it
 852         Node* phi = NULL;
 853         for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 854           Node* u = n->fast_out(i);
 855           if (has_ctrl(u)) { // control use?
 856             IdealLoopTree *u_loop = get_loop(get_ctrl(u));
 857             if (!n_loop->is_member(u_loop)) {
 858               continue;
 859             }
 860             if (u->is_Phi() && u->in(0) == n_loop->_head) {
 861               assert(_igvn.type(u) == Type::MEMORY, "bad phi");
 862               // multiple phis on the same slice are possible
 863               if (phi != NULL) {
 864                 return;
 865               }
 866               phi = u;
 867               continue;
 868             }
 869           }
 870           return;
 871         }
 872         if (phi != NULL) {
 873           // Nothing in the loop before the store (next iteration)
 874           // must observe the stored value
 875           bool mem_ok = true;
 876           {
 877             ResourceMark rm;
 878             Unique_Node_List wq;
 879             wq.push(phi);
 880             for (uint next = 0; next < wq.size() && mem_ok; ++next) {
 881               Node *m = wq.at(next);
 882               for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
 883                 Node* u = m->fast_out(i);
 884                 if (u->is_Store() || u->is_Phi()) {
 885                   if (u != n) {
 886                     wq.push(u);
 887                     mem_ok = (wq.size() <= 10);
 888                   }
 889                 } else {
 890                   mem_ok = false;
 891                   break;
 892                 }
 893               }
 894             }
 895           }
 896           if (mem_ok) {
 897             // Move the store out of the loop if the LCA of all
 898             // users (except for the phi) is outside the loop.
 899             Node* hook = new Node(1);
 900             _igvn.rehash_node_delayed(phi);
 901             int count = phi->replace_edge(n, hook);
 902             assert(count > 0, "inconsistent phi");
 903 
 904             // Compute latest point this store can go
 905             Node* lca = get_late_ctrl(n, get_ctrl(n));
 906             if (n_loop->is_member(get_loop(lca))) {
 907               // LCA is in the loop - bail out
 908               _igvn.replace_node(hook, n);
 909               return;
 910             }
 911 #ifdef ASSERT
 912             if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
 913               assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
 914               n_loop->_head->as_Loop()->verify_strip_mined(1);
 915               Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
 916               IdealLoopTree* outer_loop = get_loop(outer);
 917               assert(n_loop->_parent == outer_loop, "broken loop tree");
 918               assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
 919             }
 920 #endif
 921 
 922             // Move store out of the loop
 923             _igvn.replace_node(hook, n->in(MemNode::Memory));
 924             _igvn.replace_input_of(n, 0, lca);
 925             set_ctrl_and_loop(n, lca);
 926 
 927             // Disconnect the phi now. An empty phi can confuse other
 928             // optimizations in this pass of loop opts..
 929             if (phi->in(LoopNode::LoopBackControl) == phi) {
 930               _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
 931               n_loop->_body.yank(phi);
 932             }
 933           }
 934         }
 935       }
 936     }
 937   }
 938 }
 939 
 940 //------------------------------split_if_with_blocks_pre-----------------------
 941 // Do the real work in a non-recursive function.  Data nodes want to be
 942 // cloned in the pre-order so they can feed each other nicely.
 943 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
 944   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 945   Node* bs_res = bs->split_if_pre(this, n);
 946   if (bs_res != NULL) {
 947     return bs_res;
 948   }
 949   // Cloning these guys is unlikely to win
 950   int n_op = n->Opcode();
 951   if( n_op == Op_MergeMem ) return n;
 952   if( n->is_Proj() ) return n;
 953   // Do not clone-up CmpFXXX variations, as these are always
 954   // followed by a CmpI
 955   if( n->is_Cmp() ) return n;
 956   // Attempt to use a conditional move instead of a phi/branch
 957   if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
 958     Node *cmov = conditional_move( n );
 959     if( cmov ) return cmov;
 960   }
 961   if( n->is_CFG() || n->is_LoadStore() )
 962     return n;
 963   if( n_op == Op_Opaque1 ||     // Opaque nodes cannot be mod'd
 964       n_op == Op_Opaque2 ) {
 965     if( !C->major_progress() )   // If chance of no more loop opts...
 966       _igvn._worklist.push(n);  // maybe we'll remove them
 967     return n;
 968   }
 969 
 970   if( n->is_Con() ) return n;   // No cloning for Con nodes
 971 
 972   Node *n_ctrl = get_ctrl(n);
 973   if( !n_ctrl ) return n;       // Dead node
 974 
 975   Node* res = try_move_store_before_loop(n, n_ctrl);
 976   if (res != NULL) {
 977     return n;
 978   }
 979 
 980   // Attempt to remix address expressions for loop invariants
 981   Node *m = remix_address_expressions( n );
 982   if( m ) return m;
 983 
 984   if (n_op == Op_AddI) {
 985     Node *nn = convert_add_to_muladd( n );
 986     if ( nn ) return nn;
 987   }
 988 
 989   if (n->is_ConstraintCast()) {
 990     Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
 991     // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
 992     // Node control inputs don't necessarily agree with loop control info (due to
 993     // transformations happened in between), thus additional dominance check is needed
 994     // to keep loop info valid.
 995     if (dom_cast != NULL && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
 996       _igvn.replace_node(n, dom_cast);
 997       return dom_cast;
 998     }
 999   }
1000 
1001   // Determine if the Node has inputs from some local Phi.
1002   // Returns the block to clone thru.
1003   Node *n_blk = has_local_phi_input( n );
1004   if( !n_blk ) return n;
1005 
1006   // Do not clone the trip counter through on a CountedLoop
1007   // (messes up the canonical shape).
1008   if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
1009 
1010   // Check for having no control input; not pinned.  Allow
1011   // dominating control.
1012   if (n->in(0)) {
1013     Node *dom = idom(n_blk);
1014     if (dom_lca(n->in(0), dom) != n->in(0)) {
1015       return n;
1016     }
1017   }
1018   // Policy: when is it profitable.  You must get more wins than
1019   // policy before it is considered profitable.  Policy is usually 0,
1020   // so 1 win is considered profitable.  Big merges will require big
1021   // cloning, so get a larger policy.
1022   int policy = n_blk->req() >> 2;
1023 
1024   // If the loop is a candidate for range check elimination,
1025   // delay splitting through it's phi until a later loop optimization
1026   if (n_blk->is_CountedLoop()) {
1027     IdealLoopTree *lp = get_loop(n_blk);
1028     if (lp && lp->_rce_candidate) {
1029       return n;
1030     }
1031   }
1032 
1033   // Use same limit as split_if_with_blocks_post
1034   if( C->live_nodes() > 35000 ) return n; // Method too big
1035 
1036   // Split 'n' through the merge point if it is profitable
1037   Node *phi = split_thru_phi( n, n_blk, policy );
1038   if (!phi) return n;
1039 
1040   // Found a Phi to split thru!
1041   // Replace 'n' with the new phi
1042   _igvn.replace_node( n, phi );
1043   // Moved a load around the loop, 'en-registering' something.
1044   if (n_blk->is_Loop() && n->is_Load() &&
1045       !phi->in(LoopNode::LoopBackControl)->is_Load())
1046     C->set_major_progress();
1047 
1048   return phi;
1049 }
1050 
1051 static bool merge_point_too_heavy(Compile* C, Node* region) {
1052   // Bail out if the region and its phis have too many users.
1053   int weight = 0;
1054   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1055     weight += region->fast_out(i)->outcnt();
1056   }
1057   int nodes_left = C->max_node_limit() - C->live_nodes();
1058   if (weight * 8 > nodes_left) {
1059     if (PrintOpto) {
1060       tty->print_cr("*** Split-if bails out:  %d nodes, region weight %d", C->unique(), weight);
1061     }
1062     return true;
1063   } else {
1064     return false;
1065   }
1066 }
1067 
1068 static bool merge_point_safe(Node* region) {
1069   // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1070   // having a PhiNode input. This sidesteps the dangerous case where the split
1071   // ConvI2LNode may become TOP if the input Value() does not
1072   // overlap the ConvI2L range, leaving a node which may not dominate its
1073   // uses.
1074   // A better fix for this problem can be found in the BugTraq entry, but
1075   // expediency for Mantis demands this hack.
1076   // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
1077   // split_if_with_blocks from splitting a block because we could not move around
1078   // the FastLockNode.
1079   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1080     Node* n = region->fast_out(i);
1081     if (n->is_Phi()) {
1082       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1083         Node* m = n->fast_out(j);
1084         if (m->is_FastLock())
1085           return false;
1086 #if INCLUDE_SHENANDOAHGC
1087         if (m->is_ShenandoahBarrier() && m->has_out_with(Op_FastLock)) {
1088           return false;
1089         }
1090 #endif
1091 #ifdef _LP64
1092         if (m->Opcode() == Op_ConvI2L)
1093           return false;
1094         if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1095           return false;
1096         }
1097 #endif
1098       }
1099     }
1100   }
1101   return true;
1102 }
1103 
1104 
1105 //------------------------------place_near_use---------------------------------
1106 // Place some computation next to use but not inside inner loops.
1107 // For inner loop uses move it to the preheader area.
1108 Node *PhaseIdealLoop::place_near_use(Node *useblock) const {
1109   IdealLoopTree *u_loop = get_loop( useblock );
1110   if (u_loop->_irreducible) {
1111     return useblock;
1112   }
1113   if (u_loop->_child) {
1114     if (useblock == u_loop->_head && u_loop->_head->is_OuterStripMinedLoop()) {
1115       return u_loop->_head->in(LoopNode::EntryControl);
1116     }
1117     return useblock;
1118   }
1119   return u_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1120 }
1121 
1122 
1123 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1124   if (!n->is_If() || n->is_CountedLoopEnd()) {
1125     return false;
1126   }
1127   if (!n->in(0)->is_Region()) {
1128     return false;
1129   }
1130   Node* region = n->in(0);
1131   Node* dom = idom(region);
1132   if (!dom->is_If() || dom->in(1) != n->in(1)) {
1133     return false;
1134   }
1135   IfNode* dom_if = dom->as_If();
1136   Node* proj_true = dom_if->proj_out(1);
1137   Node* proj_false = dom_if->proj_out(0);
1138 
1139   for (uint i = 1; i < region->req(); i++) {
1140     if (is_dominator(proj_true, region->in(i))) {
1141       continue;
1142     }
1143     if (is_dominator(proj_false, region->in(i))) {
1144       continue;
1145     }
1146     return false;
1147   }
1148 
1149   return true;
1150 }
1151 
1152 bool PhaseIdealLoop::can_split_if(Node *n_ctrl) {
1153   if (C->live_nodes() > 35000) {
1154     return false; // Method too big
1155   }
1156 
1157   // Do not do 'split-if' if irreducible loops are present.
1158   if (_has_irreducible_loops) {
1159     return false;
1160   }
1161 
1162   if (merge_point_too_heavy(C, n_ctrl)) {
1163     return false;
1164   }
1165 
1166   // Do not do 'split-if' if some paths are dead.  First do dead code
1167   // elimination and then see if its still profitable.
1168   for (uint i = 1; i < n_ctrl->req(); i++) {
1169     if (n_ctrl->in(i) == C->top()) {
1170       return false;
1171     }
1172   }
1173 
1174   // If trying to do a 'Split-If' at the loop head, it is only
1175   // profitable if the cmp folds up on BOTH paths.  Otherwise we
1176   // risk peeling a loop forever.
1177 
1178   // CNC - Disabled for now.  Requires careful handling of loop
1179   // body selection for the cloned code.  Also, make sure we check
1180   // for any input path not being in the same loop as n_ctrl.  For
1181   // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1182   // because the alternative loop entry points won't be converted
1183   // into LoopNodes.
1184   IdealLoopTree *n_loop = get_loop(n_ctrl);
1185   for (uint j = 1; j < n_ctrl->req(); j++) {
1186     if (get_loop(n_ctrl->in(j)) != n_loop) {
1187       return false;
1188     }
1189   }
1190 
1191   // Check for safety of the merge point.
1192   if (!merge_point_safe(n_ctrl)) {
1193     return false;
1194   }
1195 
1196   return true;
1197 }
1198 
1199 //------------------------------split_if_with_blocks_post----------------------
1200 // Do the real work in a non-recursive function.  CFG hackery wants to be
1201 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1202 // info.
1203 void PhaseIdealLoop::split_if_with_blocks_post(Node *n, bool last_round) {
1204 
1205   // Cloning Cmp through Phi's involves the split-if transform.
1206   // FastLock is not used by an If
1207   if (n->is_Cmp() && !n->is_FastLock() && !last_round) {
1208     Node *n_ctrl = get_ctrl(n);
1209     // Determine if the Node has inputs from some local Phi.
1210     // Returns the block to clone thru.
1211     Node *n_blk = has_local_phi_input(n);
1212     if (n_blk != n_ctrl) {
1213       return;
1214     }
1215 
1216     if (!can_split_if(n_ctrl)) {
1217       return;
1218     }
1219 
1220     if (n->outcnt() != 1) {
1221       return; // Multiple bool's from 1 compare?
1222     }
1223     Node *bol = n->unique_out();
1224     assert(bol->is_Bool(), "expect a bool here");
1225     if (bol->outcnt() != 1) {
1226       return;// Multiple branches from 1 compare?
1227     }
1228     Node *iff = bol->unique_out();
1229 
1230     // Check some safety conditions
1231     if (iff->is_If()) {        // Classic split-if?
1232       if (iff->in(0) != n_ctrl) {
1233         return; // Compare must be in same blk as if
1234       }
1235     } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1236       // Can't split CMove with different control edge.
1237       if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) {
1238         return;
1239       }
1240       if (get_ctrl(iff->in(2)) == n_ctrl ||
1241           get_ctrl(iff->in(3)) == n_ctrl) {
1242         return;                 // Inputs not yet split-up
1243       }
1244       if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1245         return;                 // Loop-invar test gates loop-varying CMOVE
1246       }
1247     } else {
1248       return;  // some other kind of node, such as an Allocate
1249     }
1250 
1251     // When is split-if profitable?  Every 'win' on means some control flow
1252     // goes dead, so it's almost always a win.
1253     int policy = 0;
1254     // Split compare 'n' through the merge point if it is profitable
1255     Node *phi = split_thru_phi( n, n_ctrl, policy);
1256     if (!phi) {
1257       return;
1258     }
1259 
1260     // Found a Phi to split thru!
1261     // Replace 'n' with the new phi
1262     _igvn.replace_node(n, phi);
1263 
1264     // Now split the bool up thru the phi
1265     Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1266     guarantee(bolphi != NULL, "null boolean phi node");
1267 
1268     _igvn.replace_node(bol, bolphi);
1269     assert(iff->in(1) == bolphi, "");
1270 
1271     if (bolphi->Value(&_igvn)->singleton()) {
1272       return;
1273     }
1274 
1275     // Conditional-move?  Must split up now
1276     if (!iff->is_If()) {
1277       Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1278       _igvn.replace_node(iff, cmovphi);
1279       return;
1280     }
1281 
1282     // Now split the IF
1283     do_split_if(iff);
1284     return;
1285   }
1286 
1287   // Two identical ifs back to back can be merged
1288   if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1289     Node *n_ctrl = n->in(0);
1290     PhiNode* bolphi = PhiNode::make_blank(n_ctrl, n->in(1));
1291     IfNode* dom_if = idom(n_ctrl)->as_If();
1292     Node* proj_true = dom_if->proj_out(1);
1293     Node* proj_false = dom_if->proj_out(0);
1294     Node* con_true = _igvn.makecon(TypeInt::ONE);
1295     Node* con_false = _igvn.makecon(TypeInt::ZERO);
1296 
1297     for (uint i = 1; i < n_ctrl->req(); i++) {
1298       if (is_dominator(proj_true, n_ctrl->in(i))) {
1299         bolphi->init_req(i, con_true);
1300       } else {
1301         assert(is_dominator(proj_false, n_ctrl->in(i)), "bad if");
1302         bolphi->init_req(i, con_false);
1303       }
1304     }
1305     register_new_node(bolphi, n_ctrl);
1306     _igvn.replace_input_of(n, 1, bolphi);
1307 
1308     // Now split the IF
1309     do_split_if(n);
1310     return;
1311   }
1312 
1313   // Check for an IF ready to split; one that has its
1314   // condition codes input coming from a Phi at the block start.
1315   int n_op = n->Opcode();
1316 
1317   // Check for an IF being dominated by another IF same test
1318   if (n_op == Op_If ||
1319       n_op == Op_RangeCheck) {
1320     Node *bol = n->in(1);
1321     uint max = bol->outcnt();
1322     // Check for same test used more than once?
1323     if (max > 1 && bol->is_Bool()) {
1324       // Search up IDOMs to see if this IF is dominated.
1325       Node *cutoff = get_ctrl(bol);
1326 
1327       // Now search up IDOMs till cutoff, looking for a dominating test
1328       Node *prevdom = n;
1329       Node *dom = idom(prevdom);
1330       while (dom != cutoff) {
1331         if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1332           // Replace the dominated test with an obvious true or false.
1333           // Place it on the IGVN worklist for later cleanup.
1334           C->set_major_progress();
1335           dominated_by(prevdom, n, false, true);
1336 #ifndef PRODUCT
1337           if( VerifyLoopOptimizations ) verify();
1338 #endif
1339           return;
1340         }
1341         prevdom = dom;
1342         dom = idom(prevdom);
1343       }
1344     }
1345   }
1346 
1347   // See if a shared loop-varying computation has no loop-varying uses.
1348   // Happens if something is only used for JVM state in uncommon trap exits,
1349   // like various versions of induction variable+offset.  Clone the
1350   // computation per usage to allow it to sink out of the loop.
1351   if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1352     Node *n_ctrl = get_ctrl(n);
1353     IdealLoopTree *n_loop = get_loop(n_ctrl);
1354     if( n_loop != _ltree_root ) {
1355       DUIterator_Fast imax, i = n->fast_outs(imax);
1356       for (; i < imax; i++) {
1357         Node* u = n->fast_out(i);
1358         if( !has_ctrl(u) )     break; // Found control user
1359         IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1360         if( u_loop == n_loop ) break; // Found loop-varying use
1361         if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1362         if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1363       }
1364       bool did_break = (i < imax);  // Did we break out of the previous loop?
1365       if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1366         Node *late_load_ctrl = NULL;
1367         if (n->is_Load()) {
1368           // If n is a load, get and save the result from get_late_ctrl(),
1369           // to be later used in calculating the control for n's clones.
1370           clear_dom_lca_tags();
1371           late_load_ctrl = get_late_ctrl(n, n_ctrl);
1372         }
1373         // If n is a load, and the late control is the same as the current
1374         // control, then the cloning of n is a pointless exercise, because
1375         // GVN will ensure that we end up where we started.
1376         if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1377           BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1378           for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1379             Node *u = n->last_out(j); // Clone private computation per use
1380             _igvn.rehash_node_delayed(u);
1381             Node *x = n->clone(); // Clone computation
1382             Node *x_ctrl = NULL;
1383             if( u->is_Phi() ) {
1384               // Replace all uses of normal nodes.  Replace Phi uses
1385               // individually, so the separate Nodes can sink down
1386               // different paths.
1387               uint k = 1;
1388               while( u->in(k) != n ) k++;
1389               u->set_req( k, x );
1390               // x goes next to Phi input path
1391               x_ctrl = u->in(0)->in(k);
1392               --j;
1393             } else {              // Normal use
1394               // Replace all uses
1395               for( uint k = 0; k < u->req(); k++ ) {
1396                 if( u->in(k) == n ) {
1397                   u->set_req( k, x );
1398                   --j;
1399                 }
1400               }
1401               x_ctrl = get_ctrl(u);
1402             }
1403 
1404             // Find control for 'x' next to use but not inside inner loops.
1405             // For inner loop uses get the preheader area.
1406             x_ctrl = place_near_use(x_ctrl);
1407 
1408             if (bs->sink_node(this, n, x, x_ctrl, n_ctrl)) {
1409               continue;
1410             }
1411 
1412             if (n->is_Load()) {
1413               // For loads, add a control edge to a CFG node outside of the loop
1414               // to force them to not combine and return back inside the loop
1415               // during GVN optimization (4641526).
1416               //
1417               // Because we are setting the actual control input, factor in
1418               // the result from get_late_ctrl() so we respect any
1419               // anti-dependences. (6233005).
1420               x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1421 
1422               // Don't allow the control input to be a CFG splitting node.
1423               // Such nodes should only have ProjNodes as outs, e.g. IfNode
1424               // should only have IfTrueNode and IfFalseNode (4985384).
1425               x_ctrl = find_non_split_ctrl(x_ctrl);
1426               assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1427 
1428               x->set_req(0, x_ctrl);
1429             }
1430             register_new_node(x, x_ctrl);
1431 
1432             // Some institutional knowledge is needed here: 'x' is
1433             // yanked because if the optimizer runs GVN on it all the
1434             // cloned x's will common up and undo this optimization and
1435             // be forced back in the loop.  This is annoying because it
1436             // makes +VerifyOpto report false-positives on progress.  I
1437             // tried setting control edges on the x's to force them to
1438             // not combine, but the matching gets worried when it tries
1439             // to fold a StoreP and an AddP together (as part of an
1440             // address expression) and the AddP and StoreP have
1441             // different controls.
1442             if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1443           }
1444           _igvn.remove_dead_node(n);
1445         }
1446       }
1447     }
1448   }
1449 
1450   try_move_store_after_loop(n);
1451 
1452   // Check for Opaque2's who's loop has disappeared - who's input is in the
1453   // same loop nest as their output.  Remove 'em, they are no longer useful.
1454   if( n_op == Op_Opaque2 &&
1455       n->in(1) != NULL &&
1456       get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1457     _igvn.replace_node( n, n->in(1) );
1458   }
1459 
1460 #if INCLUDE_ZGC
1461   if (UseZGC) {
1462     ZBarrierSetC2::loop_optimize_gc_barrier(this, n, last_round);
1463   }
1464 #endif
1465 }
1466 
1467 //------------------------------split_if_with_blocks---------------------------
1468 // Check for aggressive application of 'split-if' optimization,
1469 // using basic block level info.
1470 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack, bool last_round) {
1471   Node *n = C->root();
1472   visited.set(n->_idx); // first, mark node as visited
1473   // Do pre-visit work for root
1474   n = split_if_with_blocks_pre( n );
1475   uint cnt = n->outcnt();
1476   uint i   = 0;
1477   while (true) {
1478     // Visit all children
1479     if (i < cnt) {
1480       Node* use = n->raw_out(i);
1481       ++i;
1482       if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1483         // Now do pre-visit work for this use
1484         use = split_if_with_blocks_pre( use );
1485         nstack.push(n, i); // Save parent and next use's index.
1486         n   = use;         // Process all children of current use.
1487         cnt = use->outcnt();
1488         i   = 0;
1489       }
1490     }
1491     else {
1492       // All of n's children have been processed, complete post-processing.
1493       if (cnt != 0 && !n->is_Con()) {
1494         assert(has_node(n), "no dead nodes");
1495         split_if_with_blocks_post( n, last_round );
1496       }
1497       if (nstack.is_empty()) {
1498         // Finished all nodes on stack.
1499         break;
1500       }
1501       // Get saved parent node and next use's index. Visit the rest of uses.
1502       n   = nstack.node();
1503       cnt = n->outcnt();
1504       i   = nstack.index();
1505       nstack.pop();
1506     }
1507   }
1508 }
1509 
1510 
1511 //=============================================================================
1512 //
1513 //                   C L O N E   A   L O O P   B O D Y
1514 //
1515 
1516 //------------------------------clone_iff--------------------------------------
1517 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1518 // "Nearly" because all Nodes have been cloned from the original in the loop,
1519 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1520 // through the Phi recursively, and return a Bool.
1521 Node* PhaseIdealLoop::clone_iff(PhiNode *phi, IdealLoopTree *loop) {
1522 
1523   // Convert this Phi into a Phi merging Bools
1524   uint i;
1525   for (i = 1; i < phi->req(); i++) {
1526     Node *b = phi->in(i);
1527     if (b->is_Phi()) {
1528       _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi(), loop));
1529     } else {
1530       assert(b->is_Bool() || b->Opcode() == Op_Opaque4, "");
1531     }
1532   }
1533 
1534   Node* n = phi->in(1);
1535   Node* sample_opaque = NULL;
1536   Node *sample_bool = NULL;
1537   if (n->Opcode() == Op_Opaque4) {
1538     sample_opaque = n;
1539     sample_bool = n->in(1);
1540     assert(sample_bool->is_Bool(), "wrong type");
1541   } else {
1542     sample_bool = n;
1543   }
1544   Node *sample_cmp = sample_bool->in(1);
1545 
1546   // Make Phis to merge the Cmp's inputs.
1547   PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
1548   PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
1549   for (i = 1; i < phi->req(); i++) {
1550     Node *n1 = sample_opaque == NULL ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
1551     Node *n2 = sample_opaque == NULL ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
1552     phi1->set_req(i, n1);
1553     phi2->set_req(i, n2);
1554     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1555     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1556   }
1557   // See if these Phis have been made before.
1558   // Register with optimizer
1559   Node *hit1 = _igvn.hash_find_insert(phi1);
1560   if (hit1) {                   // Hit, toss just made Phi
1561     _igvn.remove_dead_node(phi1); // Remove new phi
1562     assert(hit1->is_Phi(), "" );
1563     phi1 = (PhiNode*)hit1;      // Use existing phi
1564   } else {                      // Miss
1565     _igvn.register_new_node_with_optimizer(phi1);
1566   }
1567   Node *hit2 = _igvn.hash_find_insert(phi2);
1568   if (hit2) {                   // Hit, toss just made Phi
1569     _igvn.remove_dead_node(phi2); // Remove new phi
1570     assert(hit2->is_Phi(), "" );
1571     phi2 = (PhiNode*)hit2;      // Use existing phi
1572   } else {                      // Miss
1573     _igvn.register_new_node_with_optimizer(phi2);
1574   }
1575   // Register Phis with loop/block info
1576   set_ctrl(phi1, phi->in(0));
1577   set_ctrl(phi2, phi->in(0));
1578   // Make a new Cmp
1579   Node *cmp = sample_cmp->clone();
1580   cmp->set_req(1, phi1);
1581   cmp->set_req(2, phi2);
1582   _igvn.register_new_node_with_optimizer(cmp);
1583   set_ctrl(cmp, phi->in(0));
1584 
1585   // Make a new Bool
1586   Node *b = sample_bool->clone();
1587   b->set_req(1,cmp);
1588   _igvn.register_new_node_with_optimizer(b);
1589   set_ctrl(b, phi->in(0));
1590 
1591   if (sample_opaque != NULL) {
1592     Node* opaque = sample_opaque->clone();
1593     opaque->set_req(1, b);
1594     _igvn.register_new_node_with_optimizer(opaque);
1595     set_ctrl(opaque, phi->in(0));
1596     return opaque;
1597   }
1598 
1599   assert(b->is_Bool(), "");
1600   return b;
1601 }
1602 
1603 //------------------------------clone_bool-------------------------------------
1604 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1605 // "Nearly" because all Nodes have been cloned from the original in the loop,
1606 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1607 // through the Phi recursively, and return a Bool.
1608 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1609   uint i;
1610   // Convert this Phi into a Phi merging Bools
1611   for( i = 1; i < phi->req(); i++ ) {
1612     Node *b = phi->in(i);
1613     if( b->is_Phi() ) {
1614       _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1615     } else {
1616       assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1617     }
1618   }
1619 
1620   Node *sample_cmp = phi->in(1);
1621 
1622   // Make Phis to merge the Cmp's inputs.
1623   PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1624   PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1625   for( uint j = 1; j < phi->req(); j++ ) {
1626     Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1627     Node *n1, *n2;
1628     if( cmp_top->is_Cmp() ) {
1629       n1 = cmp_top->in(1);
1630       n2 = cmp_top->in(2);
1631     } else {
1632       n1 = n2 = cmp_top;
1633     }
1634     phi1->set_req( j, n1 );
1635     phi2->set_req( j, n2 );
1636     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1637     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1638   }
1639 
1640   // See if these Phis have been made before.
1641   // Register with optimizer
1642   Node *hit1 = _igvn.hash_find_insert(phi1);
1643   if( hit1 ) {                  // Hit, toss just made Phi
1644     _igvn.remove_dead_node(phi1); // Remove new phi
1645     assert( hit1->is_Phi(), "" );
1646     phi1 = (PhiNode*)hit1;      // Use existing phi
1647   } else {                      // Miss
1648     _igvn.register_new_node_with_optimizer(phi1);
1649   }
1650   Node *hit2 = _igvn.hash_find_insert(phi2);
1651   if( hit2 ) {                  // Hit, toss just made Phi
1652     _igvn.remove_dead_node(phi2); // Remove new phi
1653     assert( hit2->is_Phi(), "" );
1654     phi2 = (PhiNode*)hit2;      // Use existing phi
1655   } else {                      // Miss
1656     _igvn.register_new_node_with_optimizer(phi2);
1657   }
1658   // Register Phis with loop/block info
1659   set_ctrl(phi1, phi->in(0));
1660   set_ctrl(phi2, phi->in(0));
1661   // Make a new Cmp
1662   Node *cmp = sample_cmp->clone();
1663   cmp->set_req( 1, phi1 );
1664   cmp->set_req( 2, phi2 );
1665   _igvn.register_new_node_with_optimizer(cmp);
1666   set_ctrl(cmp, phi->in(0));
1667 
1668   assert( cmp->is_Cmp(), "" );
1669   return (CmpNode*)cmp;
1670 }
1671 
1672 //------------------------------sink_use---------------------------------------
1673 // If 'use' was in the loop-exit block, it now needs to be sunk
1674 // below the post-loop merge point.
1675 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1676   if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1677     set_ctrl(use, post_loop);
1678     for (DUIterator j = use->outs(); use->has_out(j); j++)
1679       sink_use(use->out(j), post_loop);
1680   }
1681 }
1682 
1683 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1684                                                  IdealLoopTree* loop, IdealLoopTree* outer_loop,
1685                                                  Node_List*& split_if_set, Node_List*& split_bool_set,
1686                                                  Node_List*& split_cex_set, Node_List& worklist,
1687                                                  uint new_counter, CloneLoopMode mode) {
1688   Node* nnn = old_new[old->_idx];
1689   // Copy uses to a worklist, so I can munge the def-use info
1690   // with impunity.
1691   for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1692     worklist.push(old->fast_out(j));
1693 
1694   while( worklist.size() ) {
1695     Node *use = worklist.pop();
1696     if (!has_node(use))  continue; // Ignore dead nodes
1697     if (use->in(0) == C->top())  continue;
1698     IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1699     // Check for data-use outside of loop - at least one of OLD or USE
1700     // must not be a CFG node.
1701 #ifdef ASSERT
1702     if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == NULL) {
1703       Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
1704       assert(mode == ControlAroundStripMined && use == sfpt, "missed a node");
1705     }
1706 #endif
1707     if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
1708 
1709       // If the Data use is an IF, that means we have an IF outside of the
1710       // loop that is switching on a condition that is set inside of the
1711       // loop.  Happens if people set a loop-exit flag; then test the flag
1712       // in the loop to break the loop, then test is again outside of the
1713       // loop to determine which way the loop exited.
1714       // Loop predicate If node connects to Bool node through Opaque1 node.
1715       if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use) || use->Opcode() == Op_Opaque4) {
1716         // Since this code is highly unlikely, we lazily build the worklist
1717         // of such Nodes to go split.
1718         if (!split_if_set) {
1719           ResourceArea *area = Thread::current()->resource_area();
1720           split_if_set = new Node_List(area);
1721         }
1722         split_if_set->push(use);
1723       }
1724       if (use->is_Bool()) {
1725         if (!split_bool_set) {
1726           ResourceArea *area = Thread::current()->resource_area();
1727           split_bool_set = new Node_List(area);
1728         }
1729         split_bool_set->push(use);
1730       }
1731       if (use->Opcode() == Op_CreateEx) {
1732         if (!split_cex_set) {
1733           ResourceArea *area = Thread::current()->resource_area();
1734           split_cex_set = new Node_List(area);
1735         }
1736         split_cex_set->push(use);
1737       }
1738 
1739 
1740       // Get "block" use is in
1741       uint idx = 0;
1742       while( use->in(idx) != old ) idx++;
1743       Node *prev = use->is_CFG() ? use : get_ctrl(use);
1744       assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
1745       Node *cfg = prev->_idx >= new_counter
1746         ? prev->in(2)
1747         : idom(prev);
1748       if( use->is_Phi() )     // Phi use is in prior block
1749         cfg = prev->in(idx);  // NOT in block of Phi itself
1750       if (cfg->is_top()) {    // Use is dead?
1751         _igvn.replace_input_of(use, idx, C->top());
1752         continue;
1753       }
1754 
1755       // If use is referenced through control edge... (idx == 0)
1756       if (mode == IgnoreStripMined && idx == 0) {
1757         LoopNode *head = loop->_head->as_Loop();
1758         if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
1759           // That node is outside the inner loop, leave it outside the
1760           // outer loop as well to not confuse verification code.
1761           assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
1762           _igvn.replace_input_of(use, 0, head->outer_loop_exit());
1763           continue;
1764         }
1765       }
1766 
1767       while(!outer_loop->is_member(get_loop(cfg))) {
1768         prev = cfg;
1769         cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1770       }
1771       // If the use occurs after merging several exits from the loop, then
1772       // old value must have dominated all those exits.  Since the same old
1773       // value was used on all those exits we did not need a Phi at this
1774       // merge point.  NOW we do need a Phi here.  Each loop exit value
1775       // is now merged with the peeled body exit; each exit gets its own
1776       // private Phi and those Phis need to be merged here.
1777       Node *phi;
1778       if( prev->is_Region() ) {
1779         if( idx == 0 ) {      // Updating control edge?
1780           phi = prev;         // Just use existing control
1781         } else {              // Else need a new Phi
1782           phi = PhiNode::make( prev, old );
1783           // Now recursively fix up the new uses of old!
1784           for( uint i = 1; i < prev->req(); i++ ) {
1785             worklist.push(phi); // Onto worklist once for each 'old' input
1786           }
1787         }
1788       } else {
1789         // Get new RegionNode merging old and new loop exits
1790         prev = old_new[prev->_idx];
1791         assert( prev, "just made this in step 7" );
1792         if( idx == 0) {      // Updating control edge?
1793           phi = prev;         // Just use existing control
1794         } else {              // Else need a new Phi
1795           // Make a new Phi merging data values properly
1796           phi = PhiNode::make( prev, old );
1797           phi->set_req( 1, nnn );
1798         }
1799       }
1800       // If inserting a new Phi, check for prior hits
1801       if( idx != 0 ) {
1802         Node *hit = _igvn.hash_find_insert(phi);
1803         if( hit == NULL ) {
1804           _igvn.register_new_node_with_optimizer(phi); // Register new phi
1805         } else {                                      // or
1806           // Remove the new phi from the graph and use the hit
1807           _igvn.remove_dead_node(phi);
1808           phi = hit;                                  // Use existing phi
1809         }
1810         set_ctrl(phi, prev);
1811       }
1812       // Make 'use' use the Phi instead of the old loop body exit value
1813       _igvn.replace_input_of(use, idx, phi);
1814       if( use->_idx >= new_counter ) { // If updating new phis
1815         // Not needed for correctness, but prevents a weak assert
1816         // in AddPNode from tripping (when we end up with different
1817         // base & derived Phis that will become the same after
1818         // IGVN does CSE).
1819         Node *hit = _igvn.hash_find_insert(use);
1820         if( hit )             // Go ahead and re-hash for hits.
1821           _igvn.replace_node( use, hit );
1822       }
1823 
1824       // If 'use' was in the loop-exit block, it now needs to be sunk
1825       // below the post-loop merge point.
1826       sink_use( use, prev );
1827     }
1828   }
1829 }
1830 
1831 static void clone_outer_loop_helper(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
1832                                     const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
1833                                     bool check_old_new) {
1834   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1835     Node* u = n->fast_out(j);
1836     assert(check_old_new || old_new[u->_idx] == NULL, "shouldn't have been cloned");
1837     if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == NULL)) {
1838       Node* c = phase->get_ctrl(u);
1839       IdealLoopTree* u_loop = phase->get_loop(c);
1840       assert(!loop->is_member(u_loop), "can be in outer loop or out of both loops only");
1841       if (outer_loop->is_member(u_loop)) {
1842         wq.push(u);
1843       }
1844     }
1845   }
1846 }
1847 
1848 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1849                                       IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1850                                       Node_List& extra_data_nodes) {
1851   if (head->is_strip_mined() && mode != IgnoreStripMined) {
1852     CountedLoopNode* cl = head->as_CountedLoop();
1853     Node* l = cl->outer_loop();
1854     Node* tail = cl->outer_loop_tail();
1855     IfNode* le = cl->outer_loop_end();
1856     Node* sfpt = cl->outer_safepoint();
1857     CountedLoopEndNode* cle = cl->loopexit();
1858     CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
1859     CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
1860     Node* cle_out = cle->proj_out(false);
1861 
1862     Node* new_sfpt = NULL;
1863     Node* new_cle_out = cle_out->clone();
1864     old_new.map(cle_out->_idx, new_cle_out);
1865     if (mode == CloneIncludesStripMined) {
1866       // clone outer loop body
1867       Node* new_l = l->clone();
1868       Node* new_tail = tail->clone();
1869       IfNode* new_le = le->clone()->as_If();
1870       new_sfpt = sfpt->clone();
1871 
1872       set_loop(new_l, outer_loop->_parent);
1873       set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
1874       set_loop(new_cle_out, outer_loop->_parent);
1875       set_idom(new_cle_out, new_cle, dd);
1876       set_loop(new_sfpt, outer_loop->_parent);
1877       set_idom(new_sfpt, new_cle_out, dd);
1878       set_loop(new_le, outer_loop->_parent);
1879       set_idom(new_le, new_sfpt, dd);
1880       set_loop(new_tail, outer_loop->_parent);
1881       set_idom(new_tail, new_le, dd);
1882       set_idom(new_cl, new_l, dd);
1883 
1884       old_new.map(l->_idx, new_l);
1885       old_new.map(tail->_idx, new_tail);
1886       old_new.map(le->_idx, new_le);
1887       old_new.map(sfpt->_idx, new_sfpt);
1888 
1889       new_l->set_req(LoopNode::LoopBackControl, new_tail);
1890       new_l->set_req(0, new_l);
1891       new_tail->set_req(0, new_le);
1892       new_le->set_req(0, new_sfpt);
1893       new_sfpt->set_req(0, new_cle_out);
1894       new_cle_out->set_req(0, new_cle);
1895       new_cl->set_req(LoopNode::EntryControl, new_l);
1896 
1897       _igvn.register_new_node_with_optimizer(new_l);
1898       _igvn.register_new_node_with_optimizer(new_tail);
1899       _igvn.register_new_node_with_optimizer(new_le);
1900     } else {
1901       Node *newhead = old_new[loop->_head->_idx];
1902       newhead->as_Loop()->clear_strip_mined();
1903       _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
1904       set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1905     }
1906     // Look at data node that were assigned a control in the outer
1907     // loop: they are kept in the outer loop by the safepoint so start
1908     // from the safepoint node's inputs.
1909     IdealLoopTree* outer_loop = get_loop(l);
1910     Node_Stack stack(2);
1911     stack.push(sfpt, 1);
1912     uint new_counter = C->unique();
1913     while (stack.size() > 0) {
1914       Node* n = stack.node();
1915       uint i = stack.index();
1916       while (i < n->req() &&
1917              (n->in(i) == NULL ||
1918               !has_ctrl(n->in(i)) ||
1919               get_loop(get_ctrl(n->in(i))) != outer_loop ||
1920               (old_new[n->in(i)->_idx] != NULL && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
1921         i++;
1922       }
1923       if (i < n->req()) {
1924         stack.set_index(i+1);
1925         stack.push(n->in(i), 0);
1926       } else {
1927         assert(old_new[n->_idx] == NULL || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
1928         Node* m = n == sfpt ? new_sfpt : n->clone();
1929         if (m != NULL) {
1930           for (uint i = 0; i < n->req(); i++) {
1931             if (m->in(i) != NULL && old_new[m->in(i)->_idx] != NULL) {
1932               m->set_req(i, old_new[m->in(i)->_idx]);
1933             }
1934           }
1935         } else {
1936           assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
1937         }
1938         if (n != sfpt) {
1939           extra_data_nodes.push(n);
1940           _igvn.register_new_node_with_optimizer(m);
1941           assert(get_ctrl(n) == cle_out, "what other control?");
1942           set_ctrl(m, new_cle_out);
1943           old_new.map(n->_idx, m);
1944         }
1945         stack.pop();
1946       }
1947     }
1948     if (mode == CloneIncludesStripMined) {
1949       _igvn.register_new_node_with_optimizer(new_sfpt);
1950       _igvn.register_new_node_with_optimizer(new_cle_out);
1951     }
1952     // Some other transformation may have pessimistically assign some
1953     // data nodes to the outer loop. Set their control so they are out
1954     // of the outer loop.
1955     ResourceMark rm;
1956     Unique_Node_List wq;
1957     for (uint i = 0; i < extra_data_nodes.size(); i++) {
1958       Node* old = extra_data_nodes.at(i);
1959       clone_outer_loop_helper(old, loop, outer_loop, old_new, wq, this, true);
1960     }
1961     Node* new_ctrl = cl->outer_loop_exit();
1962     assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
1963     for (uint i = 0; i < wq.size(); i++) {
1964       Node* n = wq.at(i);
1965       set_ctrl(n, new_ctrl);
1966       clone_outer_loop_helper(n, loop, outer_loop, old_new, wq, this, false);
1967     }
1968   } else {
1969     Node *newhead = old_new[loop->_head->_idx];
1970     set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1971   }
1972 }
1973 
1974 //------------------------------clone_loop-------------------------------------
1975 //
1976 //                   C L O N E   A   L O O P   B O D Y
1977 //
1978 // This is the basic building block of the loop optimizations.  It clones an
1979 // entire loop body.  It makes an old_new loop body mapping; with this mapping
1980 // you can find the new-loop equivalent to an old-loop node.  All new-loop
1981 // nodes are exactly equal to their old-loop counterparts, all edges are the
1982 // same.  All exits from the old-loop now have a RegionNode that merges the
1983 // equivalent new-loop path.  This is true even for the normal "loop-exit"
1984 // condition.  All uses of loop-invariant old-loop values now come from (one
1985 // or more) Phis that merge their new-loop equivalents.
1986 //
1987 // This operation leaves the graph in an illegal state: there are two valid
1988 // control edges coming from the loop pre-header to both loop bodies.  I'll
1989 // definitely have to hack the graph after running this transform.
1990 //
1991 // From this building block I will further edit edges to perform loop peeling
1992 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1993 //
1994 // Parameter side_by_size_idom:
1995 //   When side_by_size_idom is NULL, the dominator tree is constructed for
1996 //      the clone loop to dominate the original.  Used in construction of
1997 //      pre-main-post loop sequence.
1998 //   When nonnull, the clone and original are side-by-side, both are
1999 //      dominated by the side_by_side_idom node.  Used in construction of
2000 //      unswitched loops.
2001 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2002                                 CloneLoopMode mode, Node* side_by_side_idom) {
2003 
2004   LoopNode* head = loop->_head->as_Loop();
2005   head->verify_strip_mined(1);
2006 
2007   if (C->do_vector_loop() && PrintOpto) {
2008     const char* mname = C->method()->name()->as_quoted_ascii();
2009     if (mname != NULL) {
2010       tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2011     }
2012   }
2013 
2014   CloneMap& cm = C->clone_map();
2015   Dict* dict = cm.dict();
2016   if (C->do_vector_loop()) {
2017     cm.set_clone_idx(cm.max_gen()+1);
2018 #ifndef PRODUCT
2019     if (PrintOpto) {
2020       tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2021       loop->dump_head();
2022     }
2023 #endif
2024   }
2025 
2026   // Step 1: Clone the loop body.  Make the old->new mapping.
2027   uint i;
2028   for( i = 0; i < loop->_body.size(); i++ ) {
2029     Node *old = loop->_body.at(i);
2030     Node *nnn = old->clone();
2031     old_new.map( old->_idx, nnn );
2032     if (C->do_vector_loop()) {
2033       cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
2034     }
2035     _igvn.register_new_node_with_optimizer(nnn);
2036   }
2037 
2038   IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2039 
2040   // Step 2: Fix the edges in the new body.  If the old input is outside the
2041   // loop use it.  If the old input is INside the loop, use the corresponding
2042   // new node instead.
2043   for( i = 0; i < loop->_body.size(); i++ ) {
2044     Node *old = loop->_body.at(i);
2045     Node *nnn = old_new[old->_idx];
2046     // Fix CFG/Loop controlling the new node
2047     if (has_ctrl(old)) {
2048       set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2049     } else {
2050       set_loop(nnn, outer_loop->_parent);
2051       if (old->outcnt() > 0) {
2052         set_idom( nnn, old_new[idom(old)->_idx], dd );
2053       }
2054     }
2055     // Correct edges to the new node
2056     for( uint j = 0; j < nnn->req(); j++ ) {
2057         Node *n = nnn->in(j);
2058         if( n ) {
2059           IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
2060           if( loop->is_member( old_in_loop ) )
2061             nnn->set_req(j, old_new[n->_idx]);
2062         }
2063     }
2064     _igvn.hash_find_insert(nnn);
2065   }
2066 
2067   ResourceArea *area = Thread::current()->resource_area();
2068   Node_List extra_data_nodes(area); // data nodes in the outer strip mined loop
2069   clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2070 
2071   // Step 3: Now fix control uses.  Loop varying control uses have already
2072   // been fixed up (as part of all input edges in Step 2).  Loop invariant
2073   // control uses must be either an IfFalse or an IfTrue.  Make a merge
2074   // point to merge the old and new IfFalse/IfTrue nodes; make the use
2075   // refer to this.
2076   Node_List worklist(area);
2077   uint new_counter = C->unique();
2078   for( i = 0; i < loop->_body.size(); i++ ) {
2079     Node* old = loop->_body.at(i);
2080     if( !old->is_CFG() ) continue;
2081 
2082     // Copy uses to a worklist, so I can munge the def-use info
2083     // with impunity.
2084     for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2085       worklist.push(old->fast_out(j));
2086 
2087     while( worklist.size() ) {  // Visit all uses
2088       Node *use = worklist.pop();
2089       if (!has_node(use))  continue; // Ignore dead nodes
2090       IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2091       if( !loop->is_member( use_loop ) && use->is_CFG() ) {
2092         // Both OLD and USE are CFG nodes here.
2093         assert( use->is_Proj(), "" );
2094         Node* nnn = old_new[old->_idx];
2095 
2096         Node* newuse = NULL;
2097         if (head->is_strip_mined() && mode != IgnoreStripMined) {
2098           CountedLoopNode* cl = head->as_CountedLoop();
2099           CountedLoopEndNode* cle = cl->loopexit();
2100           Node* cle_out = cle->proj_out_or_null(false);
2101           if (use == cle_out) {
2102             IfNode* le = cl->outer_loop_end();
2103             use = le->proj_out(false);
2104             use_loop = get_loop(use);
2105             if (mode == CloneIncludesStripMined) {
2106               nnn = old_new[le->_idx];
2107             } else {
2108               newuse = old_new[cle_out->_idx];
2109             }
2110           }
2111         }
2112         if (newuse == NULL) {
2113           newuse = use->clone();
2114         }
2115 
2116         // Clone the loop exit control projection
2117         if (C->do_vector_loop()) {
2118           cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
2119         }
2120         newuse->set_req(0,nnn);
2121         _igvn.register_new_node_with_optimizer(newuse);
2122         set_loop(newuse, use_loop);
2123         set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2124 
2125         // We need a Region to merge the exit from the peeled body and the
2126         // exit from the old loop body.
2127         RegionNode *r = new RegionNode(3);
2128         // Map the old use to the new merge point
2129         old_new.map( use->_idx, r );
2130         uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
2131         assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
2132 
2133         // The original user of 'use' uses 'r' instead.
2134         for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2135           Node* useuse = use->last_out(l);
2136           _igvn.rehash_node_delayed(useuse);
2137           uint uses_found = 0;
2138           if( useuse->in(0) == use ) {
2139             useuse->set_req(0, r);
2140             uses_found++;
2141             if( useuse->is_CFG() ) {
2142               assert( dom_depth(useuse) > dd_r, "" );
2143               set_idom(useuse, r, dom_depth(useuse));
2144             }
2145           }
2146           for( uint k = 1; k < useuse->req(); k++ ) {
2147             if( useuse->in(k) == use ) {
2148               useuse->set_req(k, r);
2149               uses_found++;
2150               if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2151                 assert(dom_depth(useuse) > dd_r , "");
2152                 set_idom(useuse, r, dom_depth(useuse));
2153               }
2154             }
2155           }
2156           l -= uses_found;    // we deleted 1 or more copies of this edge
2157         }
2158 
2159         // Now finish up 'r'
2160         r->set_req( 1, newuse );
2161         r->set_req( 2,    use );
2162         _igvn.register_new_node_with_optimizer(r);
2163         set_loop(r, use_loop);
2164         set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
2165       } // End of if a loop-exit test
2166     }
2167   }
2168 
2169   // Step 4: If loop-invariant use is not control, it must be dominated by a
2170   // loop exit IfFalse/IfTrue.  Find "proper" loop exit.  Make a Region
2171   // there if needed.  Make a Phi there merging old and new used values.
2172   Node_List *split_if_set = NULL;
2173   Node_List *split_bool_set = NULL;
2174   Node_List *split_cex_set = NULL;
2175   for( i = 0; i < loop->_body.size(); i++ ) {
2176     Node* old = loop->_body.at(i);
2177     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2178                                 split_bool_set, split_cex_set, worklist, new_counter,
2179                                 mode);
2180   }
2181 
2182   for (i = 0; i < extra_data_nodes.size(); i++) {
2183     Node* old = extra_data_nodes.at(i);
2184     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2185                                 split_bool_set, split_cex_set, worklist, new_counter,
2186                                 mode);
2187   }
2188 
2189   // Check for IFs that need splitting/cloning.  Happens if an IF outside of
2190   // the loop uses a condition set in the loop.  The original IF probably
2191   // takes control from one or more OLD Regions (which in turn get from NEW
2192   // Regions).  In any case, there will be a set of Phis for each merge point
2193   // from the IF up to where the original BOOL def exists the loop.
2194   if (split_if_set) {
2195     while (split_if_set->size()) {
2196       Node *iff = split_if_set->pop();
2197       if (iff->in(1)->is_Phi()) {
2198         Node *b = clone_iff(iff->in(1)->as_Phi(), loop);
2199         _igvn.replace_input_of(iff, 1, b);
2200       }
2201     }
2202   }
2203   if (split_bool_set) {
2204     while (split_bool_set->size()) {
2205       Node *b = split_bool_set->pop();
2206       Node *phi = b->in(1);
2207       assert(phi->is_Phi(), "");
2208       CmpNode *cmp = clone_bool((PhiNode*)phi, loop);
2209       _igvn.replace_input_of(b, 1, cmp);
2210     }
2211   }
2212   if (split_cex_set) {
2213     while (split_cex_set->size()) {
2214       Node *b = split_cex_set->pop();
2215       assert(b->in(0)->is_Region(), "");
2216       assert(b->in(1)->is_Phi(), "");
2217       assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2218       split_up(b, b->in(0), NULL);
2219     }
2220   }
2221 
2222 }
2223 
2224 
2225 //---------------------- stride_of_possible_iv -------------------------------------
2226 // Looks for an iff/bool/comp with one operand of the compare
2227 // being a cycle involving an add and a phi,
2228 // with an optional truncation (left-shift followed by a right-shift)
2229 // of the add. Returns zero if not an iv.
2230 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2231   Node* trunc1 = NULL;
2232   Node* trunc2 = NULL;
2233   const TypeInt* ttype = NULL;
2234   if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
2235     return 0;
2236   }
2237   BoolNode* bl = iff->in(1)->as_Bool();
2238   Node* cmp = bl->in(1);
2239   if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2240     return 0;
2241   }
2242   // Must have an invariant operand
2243   if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2244     return 0;
2245   }
2246   Node* add2 = NULL;
2247   Node* cmp1 = cmp->in(1);
2248   if (cmp1->is_Phi()) {
2249     // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2250     Node* phi = cmp1;
2251     for (uint i = 1; i < phi->req(); i++) {
2252       Node* in = phi->in(i);
2253       Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2254                                 &trunc1, &trunc2, &ttype);
2255       if (add && add->in(1) == phi) {
2256         add2 = add->in(2);
2257         break;
2258       }
2259     }
2260   } else {
2261     // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2262     Node* addtrunc = cmp1;
2263     Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2264                                 &trunc1, &trunc2, &ttype);
2265     if (add && add->in(1)->is_Phi()) {
2266       Node* phi = add->in(1);
2267       for (uint i = 1; i < phi->req(); i++) {
2268         if (phi->in(i) == addtrunc) {
2269           add2 = add->in(2);
2270           break;
2271         }
2272       }
2273     }
2274   }
2275   if (add2 != NULL) {
2276     const TypeInt* add2t = _igvn.type(add2)->is_int();
2277     if (add2t->is_con()) {
2278       return add2t->get_con();
2279     }
2280   }
2281   return 0;
2282 }
2283 
2284 
2285 //---------------------- stay_in_loop -------------------------------------
2286 // Return the (unique) control output node that's in the loop (if it exists.)
2287 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2288   Node* unique = NULL;
2289   if (!n) return NULL;
2290   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2291     Node* use = n->fast_out(i);
2292     if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2293       if (unique != NULL) {
2294         return NULL;
2295       }
2296       unique = use;
2297     }
2298   }
2299   return unique;
2300 }
2301 
2302 //------------------------------ register_node -------------------------------------
2303 // Utility to register node "n" with PhaseIdealLoop
2304 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
2305   _igvn.register_new_node_with_optimizer(n);
2306   loop->_body.push(n);
2307   if (n->is_CFG()) {
2308     set_loop(n, loop);
2309     set_idom(n, pred, ddepth);
2310   } else {
2311     set_ctrl(n, pred);
2312   }
2313 }
2314 
2315 //------------------------------ proj_clone -------------------------------------
2316 // Utility to create an if-projection
2317 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2318   ProjNode* c = p->clone()->as_Proj();
2319   c->set_req(0, iff);
2320   return c;
2321 }
2322 
2323 //------------------------------ short_circuit_if -------------------------------------
2324 // Force the iff control output to be the live_proj
2325 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2326   guarantee(live_proj != NULL, "null projection");
2327   int proj_con = live_proj->_con;
2328   assert(proj_con == 0 || proj_con == 1, "false or true projection");
2329   Node *con = _igvn.intcon(proj_con);
2330   set_ctrl(con, C->root());
2331   if (iff) {
2332     iff->set_req(1, con);
2333   }
2334   return con;
2335 }
2336 
2337 //------------------------------ insert_if_before_proj -------------------------------------
2338 // Insert a new if before an if projection (* - new node)
2339 //
2340 // before
2341 //           if(test)
2342 //           /     \
2343 //          v       v
2344 //    other-proj   proj (arg)
2345 //
2346 // after
2347 //           if(test)
2348 //           /     \
2349 //          /       v
2350 //         |      * proj-clone
2351 //         v          |
2352 //    other-proj      v
2353 //                * new_if(relop(cmp[IU](left,right)))
2354 //                  /  \
2355 //                 v    v
2356 //         * new-proj  proj
2357 //         (returned)
2358 //
2359 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2360   IfNode* iff = proj->in(0)->as_If();
2361   IdealLoopTree *loop = get_loop(proj);
2362   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2363   int ddepth = dom_depth(proj);
2364 
2365   _igvn.rehash_node_delayed(iff);
2366   _igvn.rehash_node_delayed(proj);
2367 
2368   proj->set_req(0, NULL);  // temporary disconnect
2369   ProjNode* proj2 = proj_clone(proj, iff);
2370   register_node(proj2, loop, iff, ddepth);
2371 
2372   Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2373   register_node(cmp, loop, proj2, ddepth);
2374 
2375   BoolNode* bol = new BoolNode(cmp, relop);
2376   register_node(bol, loop, proj2, ddepth);
2377 
2378   int opcode = iff->Opcode();
2379   assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2380   IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2381     new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2382   register_node(new_if, loop, proj2, ddepth);
2383 
2384   proj->set_req(0, new_if); // reattach
2385   set_idom(proj, new_if, ddepth);
2386 
2387   ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2388   guarantee(new_exit != NULL, "null exit node");
2389   register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2390 
2391   return new_exit;
2392 }
2393 
2394 //------------------------------ insert_region_before_proj -------------------------------------
2395 // Insert a region before an if projection (* - new node)
2396 //
2397 // before
2398 //           if(test)
2399 //          /      |
2400 //         v       |
2401 //       proj      v
2402 //               other-proj
2403 //
2404 // after
2405 //           if(test)
2406 //          /      |
2407 //         v       |
2408 // * proj-clone    v
2409 //         |     other-proj
2410 //         v
2411 // * new-region
2412 //         |
2413 //         v
2414 // *      dum_if
2415 //       /     \
2416 //      v       \
2417 // * dum-proj    v
2418 //              proj
2419 //
2420 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2421   IfNode* iff = proj->in(0)->as_If();
2422   IdealLoopTree *loop = get_loop(proj);
2423   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2424   int ddepth = dom_depth(proj);
2425 
2426   _igvn.rehash_node_delayed(iff);
2427   _igvn.rehash_node_delayed(proj);
2428 
2429   proj->set_req(0, NULL);  // temporary disconnect
2430   ProjNode* proj2 = proj_clone(proj, iff);
2431   register_node(proj2, loop, iff, ddepth);
2432 
2433   RegionNode* reg = new RegionNode(2);
2434   reg->set_req(1, proj2);
2435   register_node(reg, loop, iff, ddepth);
2436 
2437   IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2438   register_node(dum_if, loop, reg, ddepth);
2439 
2440   proj->set_req(0, dum_if); // reattach
2441   set_idom(proj, dum_if, ddepth);
2442 
2443   ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2444   register_node(dum_proj, loop, dum_if, ddepth);
2445 
2446   return reg;
2447 }
2448 
2449 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2450 // Clone a signed compare loop exit from an unsigned compare and
2451 // insert it before the unsigned cmp on the stay-in-loop path.
2452 // All new nodes inserted in the dominator tree between the original
2453 // if and it's projections.  The original if test is replaced with
2454 // a constant to force the stay-in-loop path.
2455 //
2456 // This is done to make sure that the original if and it's projections
2457 // still dominate the same set of control nodes, that the ctrl() relation
2458 // from data nodes to them is preserved, and that their loop nesting is
2459 // preserved.
2460 //
2461 // before
2462 //          if(i <u limit)    unsigned compare loop exit
2463 //         /       |
2464 //        v        v
2465 //   exit-proj   stay-in-loop-proj
2466 //
2467 // after
2468 //          if(stay-in-loop-const)  original if
2469 //         /       |
2470 //        /        v
2471 //       /  if(i <  limit)    new signed test
2472 //      /  /       |
2473 //     /  /        v
2474 //    /  /  if(i <u limit)    new cloned unsigned test
2475 //   /  /   /      |
2476 //   v  v  v       |
2477 //    region       |
2478 //        |        |
2479 //      dum-if     |
2480 //     /  |        |
2481 // ether  |        |
2482 //        v        v
2483 //   exit-proj   stay-in-loop-proj
2484 //
2485 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2486   const bool Signed   = true;
2487   const bool Unsigned = false;
2488 
2489   BoolNode* bol = if_cmpu->in(1)->as_Bool();
2490   if (bol->_test._test != BoolTest::lt) return NULL;
2491   CmpNode* cmpu = bol->in(1)->as_Cmp();
2492   if (cmpu->Opcode() != Op_CmpU) return NULL;
2493   int stride = stride_of_possible_iv(if_cmpu);
2494   if (stride == 0) return NULL;
2495 
2496   Node* lp_proj = stay_in_loop(if_cmpu, loop);
2497   guarantee(lp_proj != NULL, "null loop node");
2498 
2499   ProjNode* lp_continue = lp_proj->as_Proj();
2500   ProjNode* lp_exit     = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2501 
2502   Node* limit = NULL;
2503   if (stride > 0) {
2504     limit = cmpu->in(2);
2505   } else {
2506     limit = _igvn.makecon(TypeInt::ZERO);
2507     set_ctrl(limit, C->root());
2508   }
2509   // Create a new region on the exit path
2510   RegionNode* reg = insert_region_before_proj(lp_exit);
2511   guarantee(reg != NULL, "null region node");
2512 
2513   // Clone the if-cmpu-true-false using a signed compare
2514   BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2515   ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2516   reg->add_req(cmpi_exit);
2517 
2518   // Clone the if-cmpu-true-false
2519   BoolTest::mask rel_u = bol->_test._test;
2520   ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2521   reg->add_req(cmpu_exit);
2522 
2523   // Force original if to stay in loop.
2524   short_circuit_if(if_cmpu, lp_continue);
2525 
2526   return cmpi_exit->in(0)->as_If();
2527 }
2528 
2529 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2530 // Remove a previously inserted signed compare loop exit.
2531 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2532   Node* lp_proj = stay_in_loop(if_cmp, loop);
2533   assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2534          stay_in_loop(lp_proj, loop)->is_If() &&
2535          stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2536   Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2537   set_ctrl(con, C->root());
2538   if_cmp->set_req(1, con);
2539 }
2540 
2541 //------------------------------ scheduled_nodelist -------------------------------------
2542 // Create a post order schedule of nodes that are in the
2543 // "member" set.  The list is returned in "sched".
2544 // The first node in "sched" is the loop head, followed by
2545 // nodes which have no inputs in the "member" set, and then
2546 // followed by the nodes that have an immediate input dependence
2547 // on a node in "sched".
2548 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2549 
2550   assert(member.test(loop->_head->_idx), "loop head must be in member set");
2551   Arena *a = Thread::current()->resource_area();
2552   VectorSet visited(a);
2553   Node_Stack nstack(a, loop->_body.size());
2554 
2555   Node* n  = loop->_head;  // top of stack is cached in "n"
2556   uint idx = 0;
2557   visited.set(n->_idx);
2558 
2559   // Initially push all with no inputs from within member set
2560   for(uint i = 0; i < loop->_body.size(); i++ ) {
2561     Node *elt = loop->_body.at(i);
2562     if (member.test(elt->_idx)) {
2563       bool found = false;
2564       for (uint j = 0; j < elt->req(); j++) {
2565         Node* def = elt->in(j);
2566         if (def && member.test(def->_idx) && def != elt) {
2567           found = true;
2568           break;
2569         }
2570       }
2571       if (!found && elt != loop->_head) {
2572         nstack.push(n, idx);
2573         n = elt;
2574         assert(!visited.test(n->_idx), "not seen yet");
2575         visited.set(n->_idx);
2576       }
2577     }
2578   }
2579 
2580   // traverse out's that are in the member set
2581   while (true) {
2582     if (idx < n->outcnt()) {
2583       Node* use = n->raw_out(idx);
2584       idx++;
2585       if (!visited.test_set(use->_idx)) {
2586         if (member.test(use->_idx)) {
2587           nstack.push(n, idx);
2588           n = use;
2589           idx = 0;
2590         }
2591       }
2592     } else {
2593       // All outputs processed
2594       sched.push(n);
2595       if (nstack.is_empty()) break;
2596       n   = nstack.node();
2597       idx = nstack.index();
2598       nstack.pop();
2599     }
2600   }
2601 }
2602 
2603 
2604 //------------------------------ has_use_in_set -------------------------------------
2605 // Has a use in the vector set
2606 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2607   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2608     Node* use = n->fast_out(j);
2609     if (vset.test(use->_idx)) {
2610       return true;
2611     }
2612   }
2613   return false;
2614 }
2615 
2616 
2617 //------------------------------ has_use_internal_to_set -------------------------------------
2618 // Has use internal to the vector set (ie. not in a phi at the loop head)
2619 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2620   Node* head  = loop->_head;
2621   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2622     Node* use = n->fast_out(j);
2623     if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2624       return true;
2625     }
2626   }
2627   return false;
2628 }
2629 
2630 
2631 //------------------------------ clone_for_use_outside_loop -------------------------------------
2632 // clone "n" for uses that are outside of loop
2633 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2634   int cloned = 0;
2635   assert(worklist.size() == 0, "should be empty");
2636   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2637     Node* use = n->fast_out(j);
2638     if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2639       worklist.push(use);
2640     }
2641   }
2642   while( worklist.size() ) {
2643     Node *use = worklist.pop();
2644     if (!has_node(use) || use->in(0) == C->top()) continue;
2645     uint j;
2646     for (j = 0; j < use->req(); j++) {
2647       if (use->in(j) == n) break;
2648     }
2649     assert(j < use->req(), "must be there");
2650 
2651     // clone "n" and insert it between the inputs of "n" and the use outside the loop
2652     Node* n_clone = n->clone();
2653     _igvn.replace_input_of(use, j, n_clone);
2654     cloned++;
2655     Node* use_c;
2656     if (!use->is_Phi()) {
2657       use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2658     } else {
2659       // Use in a phi is considered a use in the associated predecessor block
2660       use_c = use->in(0)->in(j);
2661     }
2662     set_ctrl(n_clone, use_c);
2663     assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2664     get_loop(use_c)->_body.push(n_clone);
2665     _igvn.register_new_node_with_optimizer(n_clone);
2666 #if !defined(PRODUCT)
2667     if (TracePartialPeeling) {
2668       tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2669     }
2670 #endif
2671   }
2672   return cloned;
2673 }
2674 
2675 
2676 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2677 // clone "n" for special uses that are in the not_peeled region.
2678 // If these def-uses occur in separate blocks, the code generator
2679 // marks the method as not compilable.  For example, if a "BoolNode"
2680 // is in a different basic block than the "IfNode" that uses it, then
2681 // the compilation is aborted in the code generator.
2682 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2683                                                         VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2684   if (n->is_Phi() || n->is_Load()) {
2685     return;
2686   }
2687   assert(worklist.size() == 0, "should be empty");
2688   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2689     Node* use = n->fast_out(j);
2690     if ( not_peel.test(use->_idx) &&
2691          (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2692          use->in(1) == n)  {
2693       worklist.push(use);
2694     }
2695   }
2696   if (worklist.size() > 0) {
2697     // clone "n" and insert it between inputs of "n" and the use
2698     Node* n_clone = n->clone();
2699     loop->_body.push(n_clone);
2700     _igvn.register_new_node_with_optimizer(n_clone);
2701     set_ctrl(n_clone, get_ctrl(n));
2702     sink_list.push(n_clone);
2703     not_peel <<= n_clone->_idx;  // add n_clone to not_peel set.
2704 #if !defined(PRODUCT)
2705     if (TracePartialPeeling) {
2706       tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2707     }
2708 #endif
2709     while( worklist.size() ) {
2710       Node *use = worklist.pop();
2711       _igvn.rehash_node_delayed(use);
2712       for (uint j = 1; j < use->req(); j++) {
2713         if (use->in(j) == n) {
2714           use->set_req(j, n_clone);
2715         }
2716       }
2717     }
2718   }
2719 }
2720 
2721 
2722 //------------------------------ insert_phi_for_loop -------------------------------------
2723 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2724 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2725   Node *phi = PhiNode::make(lp, back_edge_val);
2726   phi->set_req(LoopNode::EntryControl, lp_entry_val);
2727   // Use existing phi if it already exists
2728   Node *hit = _igvn.hash_find_insert(phi);
2729   if( hit == NULL ) {
2730     _igvn.register_new_node_with_optimizer(phi);
2731     set_ctrl(phi, lp);
2732   } else {
2733     // Remove the new phi from the graph and use the hit
2734     _igvn.remove_dead_node(phi);
2735     phi = hit;
2736   }
2737   _igvn.replace_input_of(use, idx, phi);
2738 }
2739 
2740 #ifdef ASSERT
2741 //------------------------------ is_valid_loop_partition -------------------------------------
2742 // Validate the loop partition sets: peel and not_peel
2743 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2744                                               VectorSet& not_peel ) {
2745   uint i;
2746   // Check that peel_list entries are in the peel set
2747   for (i = 0; i < peel_list.size(); i++) {
2748     if (!peel.test(peel_list.at(i)->_idx)) {
2749       return false;
2750     }
2751   }
2752   // Check at loop members are in one of peel set or not_peel set
2753   for (i = 0; i < loop->_body.size(); i++ ) {
2754     Node *def  = loop->_body.at(i);
2755     uint di = def->_idx;
2756     // Check that peel set elements are in peel_list
2757     if (peel.test(di)) {
2758       if (not_peel.test(di)) {
2759         return false;
2760       }
2761       // Must be in peel_list also
2762       bool found = false;
2763       for (uint j = 0; j < peel_list.size(); j++) {
2764         if (peel_list.at(j)->_idx == di) {
2765           found = true;
2766           break;
2767         }
2768       }
2769       if (!found) {
2770         return false;
2771       }
2772     } else if (not_peel.test(di)) {
2773       if (peel.test(di)) {
2774         return false;
2775       }
2776     } else {
2777       return false;
2778     }
2779   }
2780   return true;
2781 }
2782 
2783 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2784 // Ensure a use outside of loop is of the right form
2785 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2786   Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2787   return (use->is_Phi() &&
2788           use_c->is_Region() && use_c->req() == 3 &&
2789           (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2790            use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2791            use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2792           loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2793 }
2794 
2795 //------------------------------ is_valid_clone_loop_form -------------------------------------
2796 // Ensure that all uses outside of loop are of the right form
2797 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2798                                                uint orig_exit_idx, uint clone_exit_idx) {
2799   uint len = peel_list.size();
2800   for (uint i = 0; i < len; i++) {
2801     Node *def = peel_list.at(i);
2802 
2803     for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2804       Node *use = def->fast_out(j);
2805       Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2806       if (!loop->is_member(get_loop(use_c))) {
2807         // use is not in the loop, check for correct structure
2808         if (use->in(0) == def) {
2809           // Okay
2810         } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2811           return false;
2812         }
2813       }
2814     }
2815   }
2816   return true;
2817 }
2818 #endif
2819 
2820 //------------------------------ partial_peel -------------------------------------
2821 // Partially peel (aka loop rotation) the top portion of a loop (called
2822 // the peel section below) by cloning it and placing one copy just before
2823 // the new loop head and the other copy at the bottom of the new loop.
2824 //
2825 //    before                       after                where it came from
2826 //
2827 //    stmt1                        stmt1
2828 //  loop:                          stmt2                     clone
2829 //    stmt2                        if condA goto exitA       clone
2830 //    if condA goto exitA        new_loop:                   new
2831 //    stmt3                        stmt3                     clone
2832 //    if !condB goto loop          if condB goto exitB       clone
2833 //  exitB:                         stmt2                     orig
2834 //    stmt4                        if !condA goto new_loop   orig
2835 //  exitA:                         goto exitA
2836 //                               exitB:
2837 //                                 stmt4
2838 //                               exitA:
2839 //
2840 // Step 1: find the cut point: an exit test on probable
2841 //         induction variable.
2842 // Step 2: schedule (with cloning) operations in the peel
2843 //         section that can be executed after the cut into
2844 //         the section that is not peeled.  This may need
2845 //         to clone operations into exit blocks.  For
2846 //         instance, a reference to A[i] in the not-peel
2847 //         section and a reference to B[i] in an exit block
2848 //         may cause a left-shift of i by 2 to be placed
2849 //         in the peel block.  This step will clone the left
2850 //         shift into the exit block and sink the left shift
2851 //         from the peel to the not-peel section.
2852 // Step 3: clone the loop, retarget the control, and insert
2853 //         phis for values that are live across the new loop
2854 //         head.  This is very dependent on the graph structure
2855 //         from clone_loop.  It creates region nodes for
2856 //         exit control and associated phi nodes for values
2857 //         flow out of the loop through that exit.  The region
2858 //         node is dominated by the clone's control projection.
2859 //         So the clone's peel section is placed before the
2860 //         new loop head, and the clone's not-peel section is
2861 //         forms the top part of the new loop.  The original
2862 //         peel section forms the tail of the new loop.
2863 // Step 4: update the dominator tree and recompute the
2864 //         dominator depth.
2865 //
2866 //                   orig
2867 //
2868 //                   stmt1
2869 //                     |
2870 //                     v
2871 //               loop predicate
2872 //                     |
2873 //                     v
2874 //                   loop<----+
2875 //                     |      |
2876 //                   stmt2    |
2877 //                     |      |
2878 //                     v      |
2879 //                    ifA     |
2880 //                   / |      |
2881 //                  v  v      |
2882 //               false true   ^  <-- last_peel
2883 //               /     |      |
2884 //              /   ===|==cut |
2885 //             /     stmt3    |  <-- first_not_peel
2886 //            /        |      |
2887 //            |        v      |
2888 //            v       ifB     |
2889 //          exitA:   / \      |
2890 //                  /   \     |
2891 //                 v     v    |
2892 //               false true   |
2893 //               /       \    |
2894 //              /         ----+
2895 //             |
2896 //             v
2897 //           exitB:
2898 //           stmt4
2899 //
2900 //
2901 //            after clone loop
2902 //
2903 //                   stmt1
2904 //                     |
2905 //                     v
2906 //               loop predicate
2907 //                 /       \
2908 //        clone   /         \   orig
2909 //               /           \
2910 //              /             \
2911 //             v               v
2912 //   +---->loop                loop<----+
2913 //   |      |                    |      |
2914 //   |    stmt2                stmt2    |
2915 //   |      |                    |      |
2916 //   |      v                    v      |
2917 //   |      ifA                 ifA     |
2918 //   |      | \                / |      |
2919 //   |      v  v              v  v      |
2920 //   ^    true  false      false true   ^  <-- last_peel
2921 //   |      |   ^   \       /    |      |
2922 //   | cut==|==  \   \     /  ===|==cut |
2923 //   |    stmt3   \   \   /    stmt3    |  <-- first_not_peel
2924 //   |      |    dom   | |       |      |
2925 //   |      v      \  1v v2      v      |
2926 //   |      ifB     regionA     ifB     |
2927 //   |      / \        |       / \      |
2928 //   |     /   \       v      /   \     |
2929 //   |    v     v    exitA:  v     v    |
2930 //   |    true  false      false true   |
2931 //   |    /     ^   \      /       \    |
2932 //   +----       \   \    /         ----+
2933 //               dom  \  /
2934 //                 \  1v v2
2935 //                  regionB
2936 //                     |
2937 //                     v
2938 //                   exitB:
2939 //                   stmt4
2940 //
2941 //
2942 //           after partial peel
2943 //
2944 //                  stmt1
2945 //                     |
2946 //                     v
2947 //               loop predicate
2948 //                 /
2949 //        clone   /             orig
2950 //               /          TOP
2951 //              /             \
2952 //             v               v
2953 //    TOP->loop                loop----+
2954 //          |                    |      |
2955 //        stmt2                stmt2    |
2956 //          |                    |      |
2957 //          v                    v      |
2958 //          ifA                 ifA     |
2959 //          | \                / |      |
2960 //          v  v              v  v      |
2961 //        true  false      false true   |     <-- last_peel
2962 //          |   ^   \       /    +------|---+
2963 //  +->newloop   \   \     /  === ==cut |   |
2964 //  |     stmt3   \   \   /     TOP     |   |
2965 //  |       |    dom   | |      stmt3   |   | <-- first_not_peel
2966 //  |       v      \  1v v2      v      |   |
2967 //  |       ifB     regionA     ifB     ^   v
2968 //  |       / \        |       / \      |   |
2969 //  |      /   \       v      /   \     |   |
2970 //  |     v     v    exitA:  v     v    |   |
2971 //  |     true  false      false true   |   |
2972 //  |     /     ^   \      /       \    |   |
2973 //  |    |       \   \    /         v   |   |
2974 //  |    |       dom  \  /         TOP  |   |
2975 //  |    |         \  1v v2             |   |
2976 //  ^    v          regionB             |   |
2977 //  |    |             |                |   |
2978 //  |    |             v                ^   v
2979 //  |    |           exitB:             |   |
2980 //  |    |           stmt4              |   |
2981 //  |    +------------>-----------------+   |
2982 //  |                                       |
2983 //  +-----------------<---------------------+
2984 //
2985 //
2986 //              final graph
2987 //
2988 //                  stmt1
2989 //                    |
2990 //                    v
2991 //               loop predicate
2992 //                    |
2993 //                    v
2994 //                  stmt2 clone
2995 //                    |
2996 //                    v
2997 //         ........> ifA clone
2998 //         :        / |
2999 //        dom      /  |
3000 //         :      v   v
3001 //         :  false   true
3002 //         :  |       |
3003 //         :  |       v
3004 //         :  |    newloop<-----+
3005 //         :  |        |        |
3006 //         :  |     stmt3 clone |
3007 //         :  |        |        |
3008 //         :  |        v        |
3009 //         :  |       ifB       |
3010 //         :  |      / \        |
3011 //         :  |     v   v       |
3012 //         :  |  false true     |
3013 //         :  |   |     |       |
3014 //         :  |   v    stmt2    |
3015 //         :  | exitB:  |       |
3016 //         :  | stmt4   v       |
3017 //         :  |       ifA orig  |
3018 //         :  |      /  \       |
3019 //         :  |     /    \      |
3020 //         :  |    v     v      |
3021 //         :  |  false  true    |
3022 //         :  |  /        \     |
3023 //         :  v  v         -----+
3024 //          RegionA
3025 //             |
3026 //             v
3027 //           exitA
3028 //
3029 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3030 
3031   assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3032   if (!loop->_head->is_Loop()) {
3033     return false;  }
3034 
3035   LoopNode *head  = loop->_head->as_Loop();
3036 
3037   if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3038     return false;
3039   }
3040 
3041   // Check for complex exit control
3042   for(uint ii = 0; ii < loop->_body.size(); ii++ ) {
3043     Node *n = loop->_body.at(ii);
3044     int opc = n->Opcode();
3045     if (n->is_Call()        ||
3046         opc == Op_Catch     ||
3047         opc == Op_CatchProj ||
3048         opc == Op_Jump      ||
3049         opc == Op_JumpProj) {
3050 #if !defined(PRODUCT)
3051       if (TracePartialPeeling) {
3052         tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3053       }
3054 #endif
3055       return false;
3056     }
3057   }
3058 
3059   int dd = dom_depth(head);
3060 
3061   // Step 1: find cut point
3062 
3063   // Walk up dominators to loop head looking for first loop exit
3064   // which is executed on every path thru loop.
3065   IfNode *peel_if = NULL;
3066   IfNode *peel_if_cmpu = NULL;
3067 
3068   Node *iff = loop->tail();
3069   while( iff != head ) {
3070     if( iff->is_If() ) {
3071       Node *ctrl = get_ctrl(iff->in(1));
3072       if (ctrl->is_top()) return false; // Dead test on live IF.
3073       // If loop-varying exit-test, check for induction variable
3074       if( loop->is_member(get_loop(ctrl)) &&
3075           loop->is_loop_exit(iff) &&
3076           is_possible_iv_test(iff)) {
3077         Node* cmp = iff->in(1)->in(1);
3078         if (cmp->Opcode() == Op_CmpI) {
3079           peel_if = iff->as_If();
3080         } else {
3081           assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3082           peel_if_cmpu = iff->as_If();
3083         }
3084       }
3085     }
3086     iff = idom(iff);
3087   }
3088   // Prefer signed compare over unsigned compare.
3089   IfNode* new_peel_if = NULL;
3090   if (peel_if == NULL) {
3091     if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
3092       return false;   // No peel point found
3093     }
3094     new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3095     if (new_peel_if == NULL) {
3096       return false;   // No peel point found
3097     }
3098     peel_if = new_peel_if;
3099   }
3100   Node* last_peel        = stay_in_loop(peel_if, loop);
3101   Node* first_not_peeled = stay_in_loop(last_peel, loop);
3102   if (first_not_peeled == NULL || first_not_peeled == head) {
3103     return false;
3104   }
3105 
3106 #if !defined(PRODUCT)
3107   if (TraceLoopOpts) {
3108     tty->print("PartialPeel  ");
3109     loop->dump_head();
3110   }
3111 
3112   if (TracePartialPeeling) {
3113     tty->print_cr("before partial peel one iteration");
3114     Node_List wl;
3115     Node* t = head->in(2);
3116     while (true) {
3117       wl.push(t);
3118       if (t == head) break;
3119       t = idom(t);
3120     }
3121     while (wl.size() > 0) {
3122       Node* tt = wl.pop();
3123       tt->dump();
3124       if (tt == last_peel) tty->print_cr("-- cut --");
3125     }
3126   }
3127 #endif
3128   ResourceArea *area = Thread::current()->resource_area();
3129   VectorSet peel(area);
3130   VectorSet not_peel(area);
3131   Node_List peel_list(area);
3132   Node_List worklist(area);
3133   Node_List sink_list(area);
3134 
3135   // Set of cfg nodes to peel are those that are executable from
3136   // the head through last_peel.
3137   assert(worklist.size() == 0, "should be empty");
3138   worklist.push(head);
3139   peel.set(head->_idx);
3140   while (worklist.size() > 0) {
3141     Node *n = worklist.pop();
3142     if (n != last_peel) {
3143       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3144         Node* use = n->fast_out(j);
3145         if (use->is_CFG() &&
3146             loop->is_member(get_loop(use)) &&
3147             !peel.test_set(use->_idx)) {
3148           worklist.push(use);
3149         }
3150       }
3151     }
3152   }
3153 
3154   // Set of non-cfg nodes to peel are those that are control
3155   // dependent on the cfg nodes.
3156   uint i;
3157   for(i = 0; i < loop->_body.size(); i++ ) {
3158     Node *n = loop->_body.at(i);
3159     Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3160     if (peel.test(n_c->_idx)) {
3161       peel.set(n->_idx);
3162     } else {
3163       not_peel.set(n->_idx);
3164     }
3165   }
3166 
3167   // Step 2: move operations from the peeled section down into the
3168   //         not-peeled section
3169 
3170   // Get a post order schedule of nodes in the peel region
3171   // Result in right-most operand.
3172   scheduled_nodelist(loop, peel, peel_list );
3173 
3174   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3175 
3176   // For future check for too many new phis
3177   uint old_phi_cnt = 0;
3178   for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3179     Node* use = head->fast_out(j);
3180     if (use->is_Phi()) old_phi_cnt++;
3181   }
3182 
3183 #if !defined(PRODUCT)
3184   if (TracePartialPeeling) {
3185     tty->print_cr("\npeeled list");
3186   }
3187 #endif
3188 
3189   // Evacuate nodes in peel region into the not_peeled region if possible
3190   uint new_phi_cnt = 0;
3191   uint cloned_for_outside_use = 0;
3192   for (i = 0; i < peel_list.size();) {
3193     Node* n = peel_list.at(i);
3194 #if !defined(PRODUCT)
3195   if (TracePartialPeeling) n->dump();
3196 #endif
3197     bool incr = true;
3198     if ( !n->is_CFG() ) {
3199 
3200       if ( has_use_in_set(n, not_peel) ) {
3201 
3202         // If not used internal to the peeled region,
3203         // move "n" from peeled to not_peeled region.
3204 
3205         if ( !has_use_internal_to_set(n, peel, loop) ) {
3206 
3207           // if not pinned and not a load (which maybe anti-dependent on a store)
3208           // and not a CMove (Matcher expects only bool->cmove).
3209           if (n->in(0) == NULL && !n->is_Load() && !n->is_CMove() && n->Opcode() != Op_ShenandoahWBMemProj) {
3210             cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
3211             sink_list.push(n);
3212             peel     >>= n->_idx; // delete n from peel set.
3213             not_peel <<= n->_idx; // add n to not_peel set.
3214             peel_list.remove(i);
3215             incr = false;
3216 #if !defined(PRODUCT)
3217             if (TracePartialPeeling) {
3218               tty->print_cr("sink to not_peeled region: %d newbb: %d",
3219                             n->_idx, get_ctrl(n)->_idx);
3220             }
3221 #endif
3222           }
3223         } else {
3224           // Otherwise check for special def-use cases that span
3225           // the peel/not_peel boundary such as bool->if
3226           clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
3227           new_phi_cnt++;
3228         }
3229       }
3230     }
3231     if (incr) i++;
3232   }
3233 
3234   if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
3235 #if !defined(PRODUCT)
3236     if (TracePartialPeeling) {
3237       tty->print_cr("\nToo many new phis: %d  old %d new cmpi: %c",
3238                     new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
3239     }
3240 #endif
3241     if (new_peel_if != NULL) {
3242       remove_cmpi_loop_exit(new_peel_if, loop);
3243     }
3244     // Inhibit more partial peeling on this loop
3245     assert(!head->is_partial_peel_loop(), "not partial peeled");
3246     head->mark_partial_peel_failed();
3247     if (cloned_for_outside_use > 0) {
3248       // Terminate this round of loop opts because
3249       // the graph outside this loop was changed.
3250       C->set_major_progress();
3251       return true;
3252     }
3253     return false;
3254   }
3255 
3256   // Step 3: clone loop, retarget control, and insert new phis
3257 
3258   // Create new loop head for new phis and to hang
3259   // the nodes being moved (sinked) from the peel region.
3260   LoopNode* new_head = new LoopNode(last_peel, last_peel);
3261   new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3262   _igvn.register_new_node_with_optimizer(new_head);
3263   assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3264   _igvn.replace_input_of(first_not_peeled, 0, new_head);
3265   set_loop(new_head, loop);
3266   loop->_body.push(new_head);
3267   not_peel.set(new_head->_idx);
3268   set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3269   set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
3270 
3271   while (sink_list.size() > 0) {
3272     Node* n = sink_list.pop();
3273     set_ctrl(n, new_head);
3274   }
3275 
3276   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3277 
3278   clone_loop(loop, old_new, dd, IgnoreStripMined);
3279 
3280   const uint clone_exit_idx = 1;
3281   const uint orig_exit_idx  = 2;
3282   assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
3283 
3284   Node* head_clone             = old_new[head->_idx];
3285   LoopNode* new_head_clone     = old_new[new_head->_idx]->as_Loop();
3286   Node* orig_tail_clone        = head_clone->in(2);
3287 
3288   // Add phi if "def" node is in peel set and "use" is not
3289 
3290   for(i = 0; i < peel_list.size(); i++ ) {
3291     Node *def  = peel_list.at(i);
3292     if (!def->is_CFG()) {
3293       for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3294         Node *use = def->fast_out(j);
3295         if (has_node(use) && use->in(0) != C->top() &&
3296             (!peel.test(use->_idx) ||
3297              (use->is_Phi() && use->in(0) == head)) ) {
3298           worklist.push(use);
3299         }
3300       }
3301       while( worklist.size() ) {
3302         Node *use = worklist.pop();
3303         for (uint j = 1; j < use->req(); j++) {
3304           Node* n = use->in(j);
3305           if (n == def) {
3306 
3307             // "def" is in peel set, "use" is not in peel set
3308             // or "use" is in the entry boundary (a phi) of the peel set
3309 
3310             Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
3311 
3312             if ( loop->is_member(get_loop( use_c )) ) {
3313               // use is in loop
3314               if (old_new[use->_idx] != NULL) { // null for dead code
3315                 Node* use_clone = old_new[use->_idx];
3316                 _igvn.replace_input_of(use, j, C->top());
3317                 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
3318               }
3319             } else {
3320               assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
3321               // use is not in the loop, check if the live range includes the cut
3322               Node* lp_if = use_c->in(orig_exit_idx)->in(0);
3323               if (not_peel.test(lp_if->_idx)) {
3324                 assert(j == orig_exit_idx, "use from original loop");
3325                 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3326               }
3327             }
3328           }
3329         }
3330       }
3331     }
3332   }
3333 
3334   // Step 3b: retarget control
3335 
3336   // Redirect control to the new loop head if a cloned node in
3337   // the not_peeled region has control that points into the peeled region.
3338   // This necessary because the cloned peeled region will be outside
3339   // the loop.
3340   //                            from    to
3341   //          cloned-peeled    <---+
3342   //    new_head_clone:            |    <--+
3343   //          cloned-not_peeled  in(0)    in(0)
3344   //          orig-peeled
3345 
3346   for(i = 0; i < loop->_body.size(); i++ ) {
3347     Node *n = loop->_body.at(i);
3348     if (!n->is_CFG()           && n->in(0) != NULL        &&
3349         not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3350       Node* n_clone = old_new[n->_idx];
3351       _igvn.replace_input_of(n_clone, 0, new_head_clone);
3352     }
3353   }
3354 
3355   // Backedge of the surviving new_head (the clone) is original last_peel
3356   _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3357 
3358   // Cut first node in original not_peel set
3359   _igvn.rehash_node_delayed(new_head);                     // Multiple edge updates:
3360   new_head->set_req(LoopNode::EntryControl,    C->top());  //   use rehash_node_delayed / set_req instead of
3361   new_head->set_req(LoopNode::LoopBackControl, C->top());  //   multiple replace_input_of calls
3362 
3363   // Copy head_clone back-branch info to original head
3364   // and remove original head's loop entry and
3365   // clone head's back-branch
3366   _igvn.rehash_node_delayed(head); // Multiple edge updates
3367   head->set_req(LoopNode::EntryControl,    head_clone->in(LoopNode::LoopBackControl));
3368   head->set_req(LoopNode::LoopBackControl, C->top());
3369   _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3370 
3371   // Similarly modify the phis
3372   for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3373     Node* use = head->fast_out(k);
3374     if (use->is_Phi() && use->outcnt() > 0) {
3375       Node* use_clone = old_new[use->_idx];
3376       _igvn.rehash_node_delayed(use); // Multiple edge updates
3377       use->set_req(LoopNode::EntryControl,    use_clone->in(LoopNode::LoopBackControl));
3378       use->set_req(LoopNode::LoopBackControl, C->top());
3379       _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3380     }
3381   }
3382 
3383   // Step 4: update dominator tree and dominator depth
3384 
3385   set_idom(head, orig_tail_clone, dd);
3386   recompute_dom_depth();
3387 
3388   // Inhibit more partial peeling on this loop
3389   new_head_clone->set_partial_peel_loop();
3390   C->set_major_progress();
3391   loop->record_for_igvn();
3392 
3393 #if !defined(PRODUCT)
3394   if (TracePartialPeeling) {
3395     tty->print_cr("\nafter partial peel one iteration");
3396     Node_List wl(area);
3397     Node* t = last_peel;
3398     while (true) {
3399       wl.push(t);
3400       if (t == head_clone) break;
3401       t = idom(t);
3402     }
3403     while (wl.size() > 0) {
3404       Node* tt = wl.pop();
3405       if (tt == head) tty->print_cr("orig head");
3406       else if (tt == new_head_clone) tty->print_cr("new head");
3407       else if (tt == head_clone) tty->print_cr("clone head");
3408       tt->dump();
3409     }
3410   }
3411 #endif
3412   return true;
3413 }
3414 
3415 //------------------------------reorg_offsets----------------------------------
3416 // Reorganize offset computations to lower register pressure.  Mostly
3417 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3418 // then alive with the post-incremented trip counter forcing an extra
3419 // register move)
3420 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3421   // Perform it only for canonical counted loops.
3422   // Loop's shape could be messed up by iteration_split_impl.
3423   if (!loop->_head->is_CountedLoop())
3424     return;
3425   if (!loop->_head->as_Loop()->is_valid_counted_loop())
3426     return;
3427 
3428   CountedLoopNode *cl = loop->_head->as_CountedLoop();
3429   CountedLoopEndNode *cle = cl->loopexit();
3430   Node *exit = cle->proj_out(false);
3431   Node *phi = cl->phi();
3432 
3433   // Check for the special case of folks using the pre-incremented
3434   // trip-counter on the fall-out path (forces the pre-incremented
3435   // and post-incremented trip counter to be live at the same time).
3436   // Fix this by adjusting to use the post-increment trip counter.
3437 
3438   bool progress = true;
3439   while (progress) {
3440     progress = false;
3441     for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3442       Node* use = phi->fast_out(i);   // User of trip-counter
3443       if (!has_ctrl(use))  continue;
3444       Node *u_ctrl = get_ctrl(use);
3445       if (use->is_Phi()) {
3446         u_ctrl = NULL;
3447         for (uint j = 1; j < use->req(); j++)
3448           if (use->in(j) == phi)
3449             u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3450       }
3451       IdealLoopTree *u_loop = get_loop(u_ctrl);
3452       // Look for loop-invariant use
3453       if (u_loop == loop) continue;
3454       if (loop->is_member(u_loop)) continue;
3455       // Check that use is live out the bottom.  Assuming the trip-counter
3456       // update is right at the bottom, uses of of the loop middle are ok.
3457       if (dom_lca(exit, u_ctrl) != exit) continue;
3458       // Hit!  Refactor use to use the post-incremented tripcounter.
3459       // Compute a post-increment tripcounter.
3460       Node* c = exit;
3461       if (cl->is_strip_mined()) {
3462         IdealLoopTree* outer_loop = get_loop(cl->outer_loop());
3463         if (!outer_loop->is_member(u_loop)) {
3464           c = cl->outer_loop_exit();
3465         }
3466       }
3467       Node *opaq = new Opaque2Node(C, cle->incr());
3468       register_new_node(opaq, c);
3469       Node *neg_stride = _igvn.intcon(-cle->stride_con());
3470       set_ctrl(neg_stride, C->root());
3471       Node *post = new AddINode(opaq, neg_stride);
3472       register_new_node(post, c);
3473       _igvn.rehash_node_delayed(use);
3474       for (uint j = 1; j < use->req(); j++) {
3475         if (use->in(j) == phi)
3476           use->set_req(j, post);
3477       }
3478       // Since DU info changed, rerun loop
3479       progress = true;
3480       break;
3481     }
3482   }
3483 
3484 }