1 /*
   2  * Copyright (c) 1999, 2019, 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   if (must_throttle_split_if()) return n;
1034 
1035   // Split 'n' through the merge point if it is profitable
1036   Node *phi = split_thru_phi( n, n_blk, policy );
1037   if (!phi) return n;
1038 
1039   // Found a Phi to split thru!
1040   // Replace 'n' with the new phi
1041   _igvn.replace_node( n, phi );
1042   // Moved a load around the loop, 'en-registering' something.
1043   if (n_blk->is_Loop() && n->is_Load() &&
1044       !phi->in(LoopNode::LoopBackControl)->is_Load())
1045     C->set_major_progress();
1046 
1047   return phi;
1048 }
1049 
1050 static bool merge_point_too_heavy(Compile* C, Node* region) {
1051   // Bail out if the region and its phis have too many users.
1052   int weight = 0;
1053   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1054     weight += region->fast_out(i)->outcnt();
1055   }
1056   int nodes_left = C->max_node_limit() - C->live_nodes();
1057   if (weight * 8 > nodes_left) {
1058     if (PrintOpto) {
1059       tty->print_cr("*** Split-if bails out:  %d nodes, region weight %d", C->unique(), weight);
1060     }
1061     return true;
1062   } else {
1063     return false;
1064   }
1065 }
1066 
1067 static bool merge_point_safe(Node* region) {
1068   // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1069   // having a PhiNode input. This sidesteps the dangerous case where the split
1070   // ConvI2LNode may become TOP if the input Value() does not
1071   // overlap the ConvI2L range, leaving a node which may not dominate its
1072   // uses.
1073   // A better fix for this problem can be found in the BugTraq entry, but
1074   // expediency for Mantis demands this hack.
1075   // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
1076   // split_if_with_blocks from splitting a block because we could not move around
1077   // the FastLockNode.
1078   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1079     Node* n = region->fast_out(i);
1080     if (n->is_Phi()) {
1081       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1082         Node* m = n->fast_out(j);
1083         if (m->is_FastLock())
1084           return false;
1085 #ifdef _LP64
1086         if (m->Opcode() == Op_ConvI2L)
1087           return false;
1088         if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1089           return false;
1090         }
1091 #endif
1092       }
1093     }
1094   }
1095   return true;
1096 }
1097 
1098 
1099 //------------------------------place_near_use---------------------------------
1100 // Place some computation next to use but not inside inner loops.
1101 // For inner loop uses move it to the preheader area.
1102 Node *PhaseIdealLoop::place_near_use(Node *useblock) const {
1103   IdealLoopTree *u_loop = get_loop( useblock );
1104   if (u_loop->_irreducible) {
1105     return useblock;
1106   }
1107   if (u_loop->_child) {
1108     if (useblock == u_loop->_head && u_loop->_head->is_OuterStripMinedLoop()) {
1109       return u_loop->_head->in(LoopNode::EntryControl);
1110     }
1111     return useblock;
1112   }
1113   return u_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1114 }
1115 
1116 
1117 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1118   if (!n->is_If() || n->is_CountedLoopEnd()) {
1119     return false;
1120   }
1121   if (!n->in(0)->is_Region()) {
1122     return false;
1123   }
1124   Node* region = n->in(0);
1125   Node* dom = idom(region);
1126   if (!dom->is_If() || dom->in(1) != n->in(1)) {
1127     return false;
1128   }
1129   IfNode* dom_if = dom->as_If();
1130   Node* proj_true = dom_if->proj_out(1);
1131   Node* proj_false = dom_if->proj_out(0);
1132 
1133   for (uint i = 1; i < region->req(); i++) {
1134     if (is_dominator(proj_true, region->in(i))) {
1135       continue;
1136     }
1137     if (is_dominator(proj_false, region->in(i))) {
1138       continue;
1139     }
1140     return false;
1141   }
1142 
1143   return true;
1144 }
1145 
1146 
1147 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1148   if (must_throttle_split_if()) {
1149     return false;
1150   }
1151 
1152   // Do not do 'split-if' if irreducible loops are present.
1153   if (_has_irreducible_loops) {
1154     return false;
1155   }
1156 
1157   if (merge_point_too_heavy(C, n_ctrl)) {
1158     return false;
1159   }
1160 
1161   // Do not do 'split-if' if some paths are dead.  First do dead code
1162   // elimination and then see if its still profitable.
1163   for (uint i = 1; i < n_ctrl->req(); i++) {
1164     if (n_ctrl->in(i) == C->top()) {
1165       return false;
1166     }
1167   }
1168 
1169   // If trying to do a 'Split-If' at the loop head, it is only
1170   // profitable if the cmp folds up on BOTH paths.  Otherwise we
1171   // risk peeling a loop forever.
1172 
1173   // CNC - Disabled for now.  Requires careful handling of loop
1174   // body selection for the cloned code.  Also, make sure we check
1175   // for any input path not being in the same loop as n_ctrl.  For
1176   // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1177   // because the alternative loop entry points won't be converted
1178   // into LoopNodes.
1179   IdealLoopTree *n_loop = get_loop(n_ctrl);
1180   for (uint j = 1; j < n_ctrl->req(); j++) {
1181     if (get_loop(n_ctrl->in(j)) != n_loop) {
1182       return false;
1183     }
1184   }
1185 
1186   // Check for safety of the merge point.
1187   if (!merge_point_safe(n_ctrl)) {
1188     return false;
1189   }
1190 
1191   return true;
1192 }
1193 
1194 //------------------------------split_if_with_blocks_post----------------------
1195 // Do the real work in a non-recursive function.  CFG hackery wants to be
1196 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1197 // info.
1198 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1199 
1200   // Cloning Cmp through Phi's involves the split-if transform.
1201   // FastLock is not used by an If
1202   if (n->is_Cmp() && !n->is_FastLock()) {
1203     Node *n_ctrl = get_ctrl(n);
1204     // Determine if the Node has inputs from some local Phi.
1205     // Returns the block to clone thru.
1206     Node *n_blk = has_local_phi_input(n);
1207     if (n_blk != n_ctrl) {
1208       return;
1209     }
1210 
1211     if (!can_split_if(n_ctrl)) {
1212       return;
1213     }
1214 
1215     if (n->outcnt() != 1) {
1216       return; // Multiple bool's from 1 compare?
1217     }
1218     Node *bol = n->unique_out();
1219     assert(bol->is_Bool(), "expect a bool here");
1220     if (bol->outcnt() != 1) {
1221       return;// Multiple branches from 1 compare?
1222     }
1223     Node *iff = bol->unique_out();
1224 
1225     // Check some safety conditions
1226     if (iff->is_If()) {        // Classic split-if?
1227       if (iff->in(0) != n_ctrl) {
1228         return; // Compare must be in same blk as if
1229       }
1230     } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1231       // Can't split CMove with different control edge.
1232       if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) {
1233         return;
1234       }
1235       if (get_ctrl(iff->in(2)) == n_ctrl ||
1236           get_ctrl(iff->in(3)) == n_ctrl) {
1237         return;                 // Inputs not yet split-up
1238       }
1239       if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1240         return;                 // Loop-invar test gates loop-varying CMOVE
1241       }
1242     } else {
1243       return;  // some other kind of node, such as an Allocate
1244     }
1245 
1246     // When is split-if profitable?  Every 'win' on means some control flow
1247     // goes dead, so it's almost always a win.
1248     int policy = 0;
1249     // Split compare 'n' through the merge point if it is profitable
1250     Node *phi = split_thru_phi( n, n_ctrl, policy);
1251     if (!phi) {
1252       return;
1253     }
1254 
1255     // Found a Phi to split thru!
1256     // Replace 'n' with the new phi
1257     _igvn.replace_node(n, phi);
1258 
1259     // Now split the bool up thru the phi
1260     Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1261     guarantee(bolphi != NULL, "null boolean phi node");
1262 
1263     _igvn.replace_node(bol, bolphi);
1264     assert(iff->in(1) == bolphi, "");
1265 
1266     if (bolphi->Value(&_igvn)->singleton()) {
1267       return;
1268     }
1269 
1270     // Conditional-move?  Must split up now
1271     if (!iff->is_If()) {
1272       Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1273       _igvn.replace_node(iff, cmovphi);
1274       return;
1275     }
1276 
1277     // Now split the IF
1278     do_split_if(iff);
1279     return;
1280   }
1281 
1282   // Two identical ifs back to back can be merged
1283   if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1284     Node *n_ctrl = n->in(0);
1285     PhiNode* bolphi = PhiNode::make_blank(n_ctrl, n->in(1));
1286     IfNode* dom_if = idom(n_ctrl)->as_If();
1287     Node* proj_true = dom_if->proj_out(1);
1288     Node* proj_false = dom_if->proj_out(0);
1289     Node* con_true = _igvn.makecon(TypeInt::ONE);
1290     Node* con_false = _igvn.makecon(TypeInt::ZERO);
1291 
1292     for (uint i = 1; i < n_ctrl->req(); i++) {
1293       if (is_dominator(proj_true, n_ctrl->in(i))) {
1294         bolphi->init_req(i, con_true);
1295       } else {
1296         assert(is_dominator(proj_false, n_ctrl->in(i)), "bad if");
1297         bolphi->init_req(i, con_false);
1298       }
1299     }
1300     register_new_node(bolphi, n_ctrl);
1301     _igvn.replace_input_of(n, 1, bolphi);
1302 
1303     // Now split the IF
1304     do_split_if(n);
1305     return;
1306   }
1307 
1308   // Check for an IF ready to split; one that has its
1309   // condition codes input coming from a Phi at the block start.
1310   int n_op = n->Opcode();
1311 
1312   // Check for an IF being dominated by another IF same test
1313   if (n_op == Op_If ||
1314       n_op == Op_RangeCheck) {
1315     Node *bol = n->in(1);
1316     uint max = bol->outcnt();
1317     // Check for same test used more than once?
1318     if (max > 1 && bol->is_Bool()) {
1319       // Search up IDOMs to see if this IF is dominated.
1320       Node *cutoff = get_ctrl(bol);
1321 
1322       // Now search up IDOMs till cutoff, looking for a dominating test
1323       Node *prevdom = n;
1324       Node *dom = idom(prevdom);
1325       while (dom != cutoff) {
1326         if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1327           // Replace the dominated test with an obvious true or false.
1328           // Place it on the IGVN worklist for later cleanup.
1329           C->set_major_progress();
1330           dominated_by(prevdom, n, false, true);
1331 #ifndef PRODUCT
1332           if( VerifyLoopOptimizations ) verify();
1333 #endif
1334           return;
1335         }
1336         prevdom = dom;
1337         dom = idom(prevdom);
1338       }
1339     }
1340   }
1341 
1342   // See if a shared loop-varying computation has no loop-varying uses.
1343   // Happens if something is only used for JVM state in uncommon trap exits,
1344   // like various versions of induction variable+offset.  Clone the
1345   // computation per usage to allow it to sink out of the loop.
1346   if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1347     Node *n_ctrl = get_ctrl(n);
1348     IdealLoopTree *n_loop = get_loop(n_ctrl);
1349     if( n_loop != _ltree_root ) {
1350       DUIterator_Fast imax, i = n->fast_outs(imax);
1351       for (; i < imax; i++) {
1352         Node* u = n->fast_out(i);
1353         if( !has_ctrl(u) )     break; // Found control user
1354         IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1355         if( u_loop == n_loop ) break; // Found loop-varying use
1356         if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1357         if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1358       }
1359       bool did_break = (i < imax);  // Did we break out of the previous loop?
1360       if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1361         Node *late_load_ctrl = NULL;
1362         if (n->is_Load()) {
1363           // If n is a load, get and save the result from get_late_ctrl(),
1364           // to be later used in calculating the control for n's clones.
1365           clear_dom_lca_tags();
1366           late_load_ctrl = get_late_ctrl(n, n_ctrl);
1367         }
1368         // If n is a load, and the late control is the same as the current
1369         // control, then the cloning of n is a pointless exercise, because
1370         // GVN will ensure that we end up where we started.
1371         if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1372           BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1373           for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1374             Node *u = n->last_out(j); // Clone private computation per use
1375             _igvn.rehash_node_delayed(u);
1376             Node *x = n->clone(); // Clone computation
1377             Node *x_ctrl = NULL;
1378             if( u->is_Phi() ) {
1379               // Replace all uses of normal nodes.  Replace Phi uses
1380               // individually, so the separate Nodes can sink down
1381               // different paths.
1382               uint k = 1;
1383               while( u->in(k) != n ) k++;
1384               u->set_req( k, x );
1385               // x goes next to Phi input path
1386               x_ctrl = u->in(0)->in(k);
1387               --j;
1388             } else {              // Normal use
1389               // Replace all uses
1390               for( uint k = 0; k < u->req(); k++ ) {
1391                 if( u->in(k) == n ) {
1392                   u->set_req( k, x );
1393                   --j;
1394                 }
1395               }
1396               x_ctrl = get_ctrl(u);
1397             }
1398 
1399             // Find control for 'x' next to use but not inside inner loops.
1400             // For inner loop uses get the preheader area.
1401             x_ctrl = place_near_use(x_ctrl);
1402 
1403             if (bs->sink_node(this, n, x, x_ctrl, n_ctrl)) {
1404               continue;
1405             }
1406 
1407             if (n->is_Load()) {
1408               // For loads, add a control edge to a CFG node outside of the loop
1409               // to force them to not combine and return back inside the loop
1410               // during GVN optimization (4641526).
1411               //
1412               // Because we are setting the actual control input, factor in
1413               // the result from get_late_ctrl() so we respect any
1414               // anti-dependences. (6233005).
1415               x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1416 
1417               // Don't allow the control input to be a CFG splitting node.
1418               // Such nodes should only have ProjNodes as outs, e.g. IfNode
1419               // should only have IfTrueNode and IfFalseNode (4985384).
1420               x_ctrl = find_non_split_ctrl(x_ctrl);
1421               assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1422 
1423               x->set_req(0, x_ctrl);
1424             }
1425             register_new_node(x, x_ctrl);
1426 
1427             // Some institutional knowledge is needed here: 'x' is
1428             // yanked because if the optimizer runs GVN on it all the
1429             // cloned x's will common up and undo this optimization and
1430             // be forced back in the loop.  This is annoying because it
1431             // makes +VerifyOpto report false-positives on progress.  I
1432             // tried setting control edges on the x's to force them to
1433             // not combine, but the matching gets worried when it tries
1434             // to fold a StoreP and an AddP together (as part of an
1435             // address expression) and the AddP and StoreP have
1436             // different controls.
1437             if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1438           }
1439           _igvn.remove_dead_node(n);
1440         }
1441       }
1442     }
1443   }
1444 
1445   try_move_store_after_loop(n);
1446 
1447   // Check for Opaque2's who's loop has disappeared - who's input is in the
1448   // same loop nest as their output.  Remove 'em, they are no longer useful.
1449   if( n_op == Op_Opaque2 &&
1450       n->in(1) != NULL &&
1451       get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1452     _igvn.replace_node( n, n->in(1) );
1453   }
1454 }
1455 
1456 //------------------------------split_if_with_blocks---------------------------
1457 // Check for aggressive application of 'split-if' optimization,
1458 // using basic block level info.
1459 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1460   Node* root = C->root();
1461   visited.set(root->_idx); // first, mark root as visited
1462   // Do pre-visit work for root
1463   Node* n   = split_if_with_blocks_pre(root);
1464   uint  cnt = n->outcnt();
1465   uint  i   = 0;
1466 
1467   while (true) {
1468     // Visit all children
1469     if (i < cnt) {
1470       Node* use = n->raw_out(i);
1471       ++i;
1472       if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1473         // Now do pre-visit work for this use
1474         use = split_if_with_blocks_pre(use);
1475         nstack.push(n, i); // Save parent and next use's index.
1476         n   = use;         // Process all children of current use.
1477         cnt = use->outcnt();
1478         i   = 0;
1479       }
1480     }
1481     else {
1482       // All of n's children have been processed, complete post-processing.
1483       if (cnt != 0 && !n->is_Con()) {
1484         assert(has_node(n), "no dead nodes");
1485         split_if_with_blocks_post(n);
1486       }
1487       if (must_throttle_split_if()) {
1488         nstack.clear();
1489       }
1490       if (nstack.is_empty()) {
1491         // Finished all nodes on stack.
1492         break;
1493       }
1494       // Get saved parent node and next use's index. Visit the rest of uses.
1495       n   = nstack.node();
1496       cnt = n->outcnt();
1497       i   = nstack.index();
1498       nstack.pop();
1499     }
1500   }
1501 }
1502 
1503 
1504 //=============================================================================
1505 //
1506 //                   C L O N E   A   L O O P   B O D Y
1507 //
1508 
1509 //------------------------------clone_iff--------------------------------------
1510 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1511 // "Nearly" because all Nodes have been cloned from the original in the loop,
1512 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1513 // through the Phi recursively, and return a Bool.
1514 Node* PhaseIdealLoop::clone_iff(PhiNode *phi, IdealLoopTree *loop) {
1515 
1516   // Convert this Phi into a Phi merging Bools
1517   uint i;
1518   for (i = 1; i < phi->req(); i++) {
1519     Node *b = phi->in(i);
1520     if (b->is_Phi()) {
1521       _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi(), loop));
1522     } else {
1523       assert(b->is_Bool() || b->Opcode() == Op_Opaque4, "");
1524     }
1525   }
1526 
1527   Node* n = phi->in(1);
1528   Node* sample_opaque = NULL;
1529   Node *sample_bool = NULL;
1530   if (n->Opcode() == Op_Opaque4) {
1531     sample_opaque = n;
1532     sample_bool = n->in(1);
1533     assert(sample_bool->is_Bool(), "wrong type");
1534   } else {
1535     sample_bool = n;
1536   }
1537   Node *sample_cmp = sample_bool->in(1);
1538 
1539   // Make Phis to merge the Cmp's inputs.
1540   PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
1541   PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
1542   for (i = 1; i < phi->req(); i++) {
1543     Node *n1 = sample_opaque == NULL ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
1544     Node *n2 = sample_opaque == NULL ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
1545     phi1->set_req(i, n1);
1546     phi2->set_req(i, n2);
1547     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1548     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1549   }
1550   // See if these Phis have been made before.
1551   // Register with optimizer
1552   Node *hit1 = _igvn.hash_find_insert(phi1);
1553   if (hit1) {                   // Hit, toss just made Phi
1554     _igvn.remove_dead_node(phi1); // Remove new phi
1555     assert(hit1->is_Phi(), "" );
1556     phi1 = (PhiNode*)hit1;      // Use existing phi
1557   } else {                      // Miss
1558     _igvn.register_new_node_with_optimizer(phi1);
1559   }
1560   Node *hit2 = _igvn.hash_find_insert(phi2);
1561   if (hit2) {                   // Hit, toss just made Phi
1562     _igvn.remove_dead_node(phi2); // Remove new phi
1563     assert(hit2->is_Phi(), "" );
1564     phi2 = (PhiNode*)hit2;      // Use existing phi
1565   } else {                      // Miss
1566     _igvn.register_new_node_with_optimizer(phi2);
1567   }
1568   // Register Phis with loop/block info
1569   set_ctrl(phi1, phi->in(0));
1570   set_ctrl(phi2, phi->in(0));
1571   // Make a new Cmp
1572   Node *cmp = sample_cmp->clone();
1573   cmp->set_req(1, phi1);
1574   cmp->set_req(2, phi2);
1575   _igvn.register_new_node_with_optimizer(cmp);
1576   set_ctrl(cmp, phi->in(0));
1577 
1578   // Make a new Bool
1579   Node *b = sample_bool->clone();
1580   b->set_req(1,cmp);
1581   _igvn.register_new_node_with_optimizer(b);
1582   set_ctrl(b, phi->in(0));
1583 
1584   if (sample_opaque != NULL) {
1585     Node* opaque = sample_opaque->clone();
1586     opaque->set_req(1, b);
1587     _igvn.register_new_node_with_optimizer(opaque);
1588     set_ctrl(opaque, phi->in(0));
1589     return opaque;
1590   }
1591 
1592   assert(b->is_Bool(), "");
1593   return b;
1594 }
1595 
1596 //------------------------------clone_bool-------------------------------------
1597 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1598 // "Nearly" because all Nodes have been cloned from the original in the loop,
1599 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1600 // through the Phi recursively, and return a Bool.
1601 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1602   uint i;
1603   // Convert this Phi into a Phi merging Bools
1604   for( i = 1; i < phi->req(); i++ ) {
1605     Node *b = phi->in(i);
1606     if( b->is_Phi() ) {
1607       _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1608     } else {
1609       assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1610     }
1611   }
1612 
1613   Node *sample_cmp = phi->in(1);
1614 
1615   // Make Phis to merge the Cmp's inputs.
1616   PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1617   PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1618   for( uint j = 1; j < phi->req(); j++ ) {
1619     Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1620     Node *n1, *n2;
1621     if( cmp_top->is_Cmp() ) {
1622       n1 = cmp_top->in(1);
1623       n2 = cmp_top->in(2);
1624     } else {
1625       n1 = n2 = cmp_top;
1626     }
1627     phi1->set_req( j, n1 );
1628     phi2->set_req( j, n2 );
1629     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1630     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1631   }
1632 
1633   // See if these Phis have been made before.
1634   // Register with optimizer
1635   Node *hit1 = _igvn.hash_find_insert(phi1);
1636   if( hit1 ) {                  // Hit, toss just made Phi
1637     _igvn.remove_dead_node(phi1); // Remove new phi
1638     assert( hit1->is_Phi(), "" );
1639     phi1 = (PhiNode*)hit1;      // Use existing phi
1640   } else {                      // Miss
1641     _igvn.register_new_node_with_optimizer(phi1);
1642   }
1643   Node *hit2 = _igvn.hash_find_insert(phi2);
1644   if( hit2 ) {                  // Hit, toss just made Phi
1645     _igvn.remove_dead_node(phi2); // Remove new phi
1646     assert( hit2->is_Phi(), "" );
1647     phi2 = (PhiNode*)hit2;      // Use existing phi
1648   } else {                      // Miss
1649     _igvn.register_new_node_with_optimizer(phi2);
1650   }
1651   // Register Phis with loop/block info
1652   set_ctrl(phi1, phi->in(0));
1653   set_ctrl(phi2, phi->in(0));
1654   // Make a new Cmp
1655   Node *cmp = sample_cmp->clone();
1656   cmp->set_req( 1, phi1 );
1657   cmp->set_req( 2, phi2 );
1658   _igvn.register_new_node_with_optimizer(cmp);
1659   set_ctrl(cmp, phi->in(0));
1660 
1661   assert( cmp->is_Cmp(), "" );
1662   return (CmpNode*)cmp;
1663 }
1664 
1665 //------------------------------sink_use---------------------------------------
1666 // If 'use' was in the loop-exit block, it now needs to be sunk
1667 // below the post-loop merge point.
1668 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1669   if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1670     set_ctrl(use, post_loop);
1671     for (DUIterator j = use->outs(); use->has_out(j); j++)
1672       sink_use(use->out(j), post_loop);
1673   }
1674 }
1675 
1676 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1677                                                  IdealLoopTree* loop, IdealLoopTree* outer_loop,
1678                                                  Node_List*& split_if_set, Node_List*& split_bool_set,
1679                                                  Node_List*& split_cex_set, Node_List& worklist,
1680                                                  uint new_counter, CloneLoopMode mode) {
1681   Node* nnn = old_new[old->_idx];
1682   // Copy uses to a worklist, so I can munge the def-use info
1683   // with impunity.
1684   for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1685     worklist.push(old->fast_out(j));
1686 
1687   while( worklist.size() ) {
1688     Node *use = worklist.pop();
1689     if (!has_node(use))  continue; // Ignore dead nodes
1690     if (use->in(0) == C->top())  continue;
1691     IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1692     // Check for data-use outside of loop - at least one of OLD or USE
1693     // must not be a CFG node.
1694 #ifdef ASSERT
1695     if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == NULL) {
1696       Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
1697       assert(mode == ControlAroundStripMined && use == sfpt, "missed a node");
1698     }
1699 #endif
1700     if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
1701 
1702       // If the Data use is an IF, that means we have an IF outside of the
1703       // loop that is switching on a condition that is set inside of the
1704       // loop.  Happens if people set a loop-exit flag; then test the flag
1705       // in the loop to break the loop, then test is again outside of the
1706       // loop to determine which way the loop exited.
1707       // Loop predicate If node connects to Bool node through Opaque1 node.
1708       if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use) || use->Opcode() == Op_Opaque4) {
1709         // Since this code is highly unlikely, we lazily build the worklist
1710         // of such Nodes to go split.
1711         if (!split_if_set) {
1712           ResourceArea *area = Thread::current()->resource_area();
1713           split_if_set = new Node_List(area);
1714         }
1715         split_if_set->push(use);
1716       }
1717       if (use->is_Bool()) {
1718         if (!split_bool_set) {
1719           ResourceArea *area = Thread::current()->resource_area();
1720           split_bool_set = new Node_List(area);
1721         }
1722         split_bool_set->push(use);
1723       }
1724       if (use->Opcode() == Op_CreateEx) {
1725         if (!split_cex_set) {
1726           ResourceArea *area = Thread::current()->resource_area();
1727           split_cex_set = new Node_List(area);
1728         }
1729         split_cex_set->push(use);
1730       }
1731 
1732 
1733       // Get "block" use is in
1734       uint idx = 0;
1735       while( use->in(idx) != old ) idx++;
1736       Node *prev = use->is_CFG() ? use : get_ctrl(use);
1737       assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
1738       Node *cfg = prev->_idx >= new_counter
1739         ? prev->in(2)
1740         : idom(prev);
1741       if( use->is_Phi() )     // Phi use is in prior block
1742         cfg = prev->in(idx);  // NOT in block of Phi itself
1743       if (cfg->is_top()) {    // Use is dead?
1744         _igvn.replace_input_of(use, idx, C->top());
1745         continue;
1746       }
1747 
1748       // If use is referenced through control edge... (idx == 0)
1749       if (mode == IgnoreStripMined && idx == 0) {
1750         LoopNode *head = loop->_head->as_Loop();
1751         if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
1752           // That node is outside the inner loop, leave it outside the
1753           // outer loop as well to not confuse verification code.
1754           assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
1755           _igvn.replace_input_of(use, 0, head->outer_loop_exit());
1756           continue;
1757         }
1758       }
1759 
1760       while(!outer_loop->is_member(get_loop(cfg))) {
1761         prev = cfg;
1762         cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1763       }
1764       // If the use occurs after merging several exits from the loop, then
1765       // old value must have dominated all those exits.  Since the same old
1766       // value was used on all those exits we did not need a Phi at this
1767       // merge point.  NOW we do need a Phi here.  Each loop exit value
1768       // is now merged with the peeled body exit; each exit gets its own
1769       // private Phi and those Phis need to be merged here.
1770       Node *phi;
1771       if( prev->is_Region() ) {
1772         if( idx == 0 ) {      // Updating control edge?
1773           phi = prev;         // Just use existing control
1774         } else {              // Else need a new Phi
1775           phi = PhiNode::make( prev, old );
1776           // Now recursively fix up the new uses of old!
1777           for( uint i = 1; i < prev->req(); i++ ) {
1778             worklist.push(phi); // Onto worklist once for each 'old' input
1779           }
1780         }
1781       } else {
1782         // Get new RegionNode merging old and new loop exits
1783         prev = old_new[prev->_idx];
1784         assert( prev, "just made this in step 7" );
1785         if( idx == 0) {      // Updating control edge?
1786           phi = prev;         // Just use existing control
1787         } else {              // Else need a new Phi
1788           // Make a new Phi merging data values properly
1789           phi = PhiNode::make( prev, old );
1790           phi->set_req( 1, nnn );
1791         }
1792       }
1793       // If inserting a new Phi, check for prior hits
1794       if( idx != 0 ) {
1795         Node *hit = _igvn.hash_find_insert(phi);
1796         if( hit == NULL ) {
1797           _igvn.register_new_node_with_optimizer(phi); // Register new phi
1798         } else {                                      // or
1799           // Remove the new phi from the graph and use the hit
1800           _igvn.remove_dead_node(phi);
1801           phi = hit;                                  // Use existing phi
1802         }
1803         set_ctrl(phi, prev);
1804       }
1805       // Make 'use' use the Phi instead of the old loop body exit value
1806       _igvn.replace_input_of(use, idx, phi);
1807       if( use->_idx >= new_counter ) { // If updating new phis
1808         // Not needed for correctness, but prevents a weak assert
1809         // in AddPNode from tripping (when we end up with different
1810         // base & derived Phis that will become the same after
1811         // IGVN does CSE).
1812         Node *hit = _igvn.hash_find_insert(use);
1813         if( hit )             // Go ahead and re-hash for hits.
1814           _igvn.replace_node( use, hit );
1815       }
1816 
1817       // If 'use' was in the loop-exit block, it now needs to be sunk
1818       // below the post-loop merge point.
1819       sink_use( use, prev );
1820     }
1821   }
1822 }
1823 
1824 static void clone_outer_loop_helper(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
1825                                     const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
1826                                     bool check_old_new) {
1827   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1828     Node* u = n->fast_out(j);
1829     assert(check_old_new || old_new[u->_idx] == NULL, "shouldn't have been cloned");
1830     if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == NULL)) {
1831       Node* c = phase->get_ctrl(u);
1832       IdealLoopTree* u_loop = phase->get_loop(c);
1833       assert(!loop->is_member(u_loop), "can be in outer loop or out of both loops only");
1834       if (outer_loop->is_member(u_loop)) {
1835         wq.push(u);
1836       }
1837     }
1838   }
1839 }
1840 
1841 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1842                                       IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1843                                       Node_List& extra_data_nodes) {
1844   if (head->is_strip_mined() && mode != IgnoreStripMined) {
1845     CountedLoopNode* cl = head->as_CountedLoop();
1846     Node* l = cl->outer_loop();
1847     Node* tail = cl->outer_loop_tail();
1848     IfNode* le = cl->outer_loop_end();
1849     Node* sfpt = cl->outer_safepoint();
1850     CountedLoopEndNode* cle = cl->loopexit();
1851     CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
1852     CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
1853     Node* cle_out = cle->proj_out(false);
1854 
1855     Node* new_sfpt = NULL;
1856     Node* new_cle_out = cle_out->clone();
1857     old_new.map(cle_out->_idx, new_cle_out);
1858     if (mode == CloneIncludesStripMined) {
1859       // clone outer loop body
1860       Node* new_l = l->clone();
1861       Node* new_tail = tail->clone();
1862       IfNode* new_le = le->clone()->as_If();
1863       new_sfpt = sfpt->clone();
1864 
1865       set_loop(new_l, outer_loop->_parent);
1866       set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
1867       set_loop(new_cle_out, outer_loop->_parent);
1868       set_idom(new_cle_out, new_cle, dd);
1869       set_loop(new_sfpt, outer_loop->_parent);
1870       set_idom(new_sfpt, new_cle_out, dd);
1871       set_loop(new_le, outer_loop->_parent);
1872       set_idom(new_le, new_sfpt, dd);
1873       set_loop(new_tail, outer_loop->_parent);
1874       set_idom(new_tail, new_le, dd);
1875       set_idom(new_cl, new_l, dd);
1876 
1877       old_new.map(l->_idx, new_l);
1878       old_new.map(tail->_idx, new_tail);
1879       old_new.map(le->_idx, new_le);
1880       old_new.map(sfpt->_idx, new_sfpt);
1881 
1882       new_l->set_req(LoopNode::LoopBackControl, new_tail);
1883       new_l->set_req(0, new_l);
1884       new_tail->set_req(0, new_le);
1885       new_le->set_req(0, new_sfpt);
1886       new_sfpt->set_req(0, new_cle_out);
1887       new_cle_out->set_req(0, new_cle);
1888       new_cl->set_req(LoopNode::EntryControl, new_l);
1889 
1890       _igvn.register_new_node_with_optimizer(new_l);
1891       _igvn.register_new_node_with_optimizer(new_tail);
1892       _igvn.register_new_node_with_optimizer(new_le);
1893     } else {
1894       Node *newhead = old_new[loop->_head->_idx];
1895       newhead->as_Loop()->clear_strip_mined();
1896       _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
1897       set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1898     }
1899     // Look at data node that were assigned a control in the outer
1900     // loop: they are kept in the outer loop by the safepoint so start
1901     // from the safepoint node's inputs.
1902     IdealLoopTree* outer_loop = get_loop(l);
1903     Node_Stack stack(2);
1904     stack.push(sfpt, 1);
1905     uint new_counter = C->unique();
1906     while (stack.size() > 0) {
1907       Node* n = stack.node();
1908       uint i = stack.index();
1909       while (i < n->req() &&
1910              (n->in(i) == NULL ||
1911               !has_ctrl(n->in(i)) ||
1912               get_loop(get_ctrl(n->in(i))) != outer_loop ||
1913               (old_new[n->in(i)->_idx] != NULL && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
1914         i++;
1915       }
1916       if (i < n->req()) {
1917         stack.set_index(i+1);
1918         stack.push(n->in(i), 0);
1919       } else {
1920         assert(old_new[n->_idx] == NULL || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
1921         Node* m = n == sfpt ? new_sfpt : n->clone();
1922         if (m != NULL) {
1923           for (uint i = 0; i < n->req(); i++) {
1924             if (m->in(i) != NULL && old_new[m->in(i)->_idx] != NULL) {
1925               m->set_req(i, old_new[m->in(i)->_idx]);
1926             }
1927           }
1928         } else {
1929           assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
1930         }
1931         if (n != sfpt) {
1932           extra_data_nodes.push(n);
1933           _igvn.register_new_node_with_optimizer(m);
1934           assert(get_ctrl(n) == cle_out, "what other control?");
1935           set_ctrl(m, new_cle_out);
1936           old_new.map(n->_idx, m);
1937         }
1938         stack.pop();
1939       }
1940     }
1941     if (mode == CloneIncludesStripMined) {
1942       _igvn.register_new_node_with_optimizer(new_sfpt);
1943       _igvn.register_new_node_with_optimizer(new_cle_out);
1944     }
1945     // Some other transformation may have pessimistically assign some
1946     // data nodes to the outer loop. Set their control so they are out
1947     // of the outer loop.
1948     ResourceMark rm;
1949     Unique_Node_List wq;
1950     for (uint i = 0; i < extra_data_nodes.size(); i++) {
1951       Node* old = extra_data_nodes.at(i);
1952       clone_outer_loop_helper(old, loop, outer_loop, old_new, wq, this, true);
1953     }
1954     Node* new_ctrl = cl->outer_loop_exit();
1955     assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
1956     for (uint i = 0; i < wq.size(); i++) {
1957       Node* n = wq.at(i);
1958       set_ctrl(n, new_ctrl);
1959       clone_outer_loop_helper(n, loop, outer_loop, old_new, wq, this, false);
1960     }
1961   } else {
1962     Node *newhead = old_new[loop->_head->_idx];
1963     set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1964   }
1965 }
1966 
1967 //------------------------------clone_loop-------------------------------------
1968 //
1969 //                   C L O N E   A   L O O P   B O D Y
1970 //
1971 // This is the basic building block of the loop optimizations.  It clones an
1972 // entire loop body.  It makes an old_new loop body mapping; with this mapping
1973 // you can find the new-loop equivalent to an old-loop node.  All new-loop
1974 // nodes are exactly equal to their old-loop counterparts, all edges are the
1975 // same.  All exits from the old-loop now have a RegionNode that merges the
1976 // equivalent new-loop path.  This is true even for the normal "loop-exit"
1977 // condition.  All uses of loop-invariant old-loop values now come from (one
1978 // or more) Phis that merge their new-loop equivalents.
1979 //
1980 // This operation leaves the graph in an illegal state: there are two valid
1981 // control edges coming from the loop pre-header to both loop bodies.  I'll
1982 // definitely have to hack the graph after running this transform.
1983 //
1984 // From this building block I will further edit edges to perform loop peeling
1985 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1986 //
1987 // Parameter side_by_size_idom:
1988 //   When side_by_size_idom is NULL, the dominator tree is constructed for
1989 //      the clone loop to dominate the original.  Used in construction of
1990 //      pre-main-post loop sequence.
1991 //   When nonnull, the clone and original are side-by-side, both are
1992 //      dominated by the side_by_side_idom node.  Used in construction of
1993 //      unswitched loops.
1994 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1995                                 CloneLoopMode mode, Node* side_by_side_idom) {
1996 
1997   LoopNode* head = loop->_head->as_Loop();
1998   head->verify_strip_mined(1);
1999 
2000   if (C->do_vector_loop() && PrintOpto) {
2001     const char* mname = C->method()->name()->as_quoted_ascii();
2002     if (mname != NULL) {
2003       tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2004     }
2005   }
2006 
2007   CloneMap& cm = C->clone_map();
2008   Dict* dict = cm.dict();
2009   if (C->do_vector_loop()) {
2010     cm.set_clone_idx(cm.max_gen()+1);
2011 #ifndef PRODUCT
2012     if (PrintOpto) {
2013       tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2014       loop->dump_head();
2015     }
2016 #endif
2017   }
2018 
2019   // Step 1: Clone the loop body.  Make the old->new mapping.
2020   uint i;
2021   for( i = 0; i < loop->_body.size(); i++ ) {
2022     Node *old = loop->_body.at(i);
2023     Node *nnn = old->clone();
2024     old_new.map( old->_idx, nnn );
2025     if (C->do_vector_loop()) {
2026       cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
2027     }
2028     _igvn.register_new_node_with_optimizer(nnn);
2029   }
2030 
2031   IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2032 
2033   // Step 2: Fix the edges in the new body.  If the old input is outside the
2034   // loop use it.  If the old input is INside the loop, use the corresponding
2035   // new node instead.
2036   for( i = 0; i < loop->_body.size(); i++ ) {
2037     Node *old = loop->_body.at(i);
2038     Node *nnn = old_new[old->_idx];
2039     // Fix CFG/Loop controlling the new node
2040     if (has_ctrl(old)) {
2041       set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2042     } else {
2043       set_loop(nnn, outer_loop->_parent);
2044       if (old->outcnt() > 0) {
2045         set_idom( nnn, old_new[idom(old)->_idx], dd );
2046       }
2047     }
2048     // Correct edges to the new node
2049     for( uint j = 0; j < nnn->req(); j++ ) {
2050         Node *n = nnn->in(j);
2051         if( n ) {
2052           IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
2053           if( loop->is_member( old_in_loop ) )
2054             nnn->set_req(j, old_new[n->_idx]);
2055         }
2056     }
2057     _igvn.hash_find_insert(nnn);
2058   }
2059 
2060   ResourceArea *area = Thread::current()->resource_area();
2061   Node_List extra_data_nodes(area); // data nodes in the outer strip mined loop
2062   clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2063 
2064   // Step 3: Now fix control uses.  Loop varying control uses have already
2065   // been fixed up (as part of all input edges in Step 2).  Loop invariant
2066   // control uses must be either an IfFalse or an IfTrue.  Make a merge
2067   // point to merge the old and new IfFalse/IfTrue nodes; make the use
2068   // refer to this.
2069   Node_List worklist(area);
2070   uint new_counter = C->unique();
2071   for( i = 0; i < loop->_body.size(); i++ ) {
2072     Node* old = loop->_body.at(i);
2073     if( !old->is_CFG() ) continue;
2074 
2075     // Copy uses to a worklist, so I can munge the def-use info
2076     // with impunity.
2077     for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2078       worklist.push(old->fast_out(j));
2079 
2080     while( worklist.size() ) {  // Visit all uses
2081       Node *use = worklist.pop();
2082       if (!has_node(use))  continue; // Ignore dead nodes
2083       IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2084       if( !loop->is_member( use_loop ) && use->is_CFG() ) {
2085         // Both OLD and USE are CFG nodes here.
2086         assert( use->is_Proj(), "" );
2087         Node* nnn = old_new[old->_idx];
2088 
2089         Node* newuse = NULL;
2090         if (head->is_strip_mined() && mode != IgnoreStripMined) {
2091           CountedLoopNode* cl = head->as_CountedLoop();
2092           CountedLoopEndNode* cle = cl->loopexit();
2093           Node* cle_out = cle->proj_out_or_null(false);
2094           if (use == cle_out) {
2095             IfNode* le = cl->outer_loop_end();
2096             use = le->proj_out(false);
2097             use_loop = get_loop(use);
2098             if (mode == CloneIncludesStripMined) {
2099               nnn = old_new[le->_idx];
2100             } else {
2101               newuse = old_new[cle_out->_idx];
2102             }
2103           }
2104         }
2105         if (newuse == NULL) {
2106           newuse = use->clone();
2107         }
2108 
2109         // Clone the loop exit control projection
2110         if (C->do_vector_loop()) {
2111           cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
2112         }
2113         newuse->set_req(0,nnn);
2114         _igvn.register_new_node_with_optimizer(newuse);
2115         set_loop(newuse, use_loop);
2116         set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2117 
2118         // We need a Region to merge the exit from the peeled body and the
2119         // exit from the old loop body.
2120         RegionNode *r = new RegionNode(3);
2121         // Map the old use to the new merge point
2122         old_new.map( use->_idx, r );
2123         uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
2124         assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
2125 
2126         // The original user of 'use' uses 'r' instead.
2127         for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2128           Node* useuse = use->last_out(l);
2129           _igvn.rehash_node_delayed(useuse);
2130           uint uses_found = 0;
2131           if( useuse->in(0) == use ) {
2132             useuse->set_req(0, r);
2133             uses_found++;
2134             if( useuse->is_CFG() ) {
2135               assert( dom_depth(useuse) > dd_r, "" );
2136               set_idom(useuse, r, dom_depth(useuse));
2137             }
2138           }
2139           for( uint k = 1; k < useuse->req(); k++ ) {
2140             if( useuse->in(k) == use ) {
2141               useuse->set_req(k, r);
2142               uses_found++;
2143               if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2144                 assert(dom_depth(useuse) > dd_r , "");
2145                 set_idom(useuse, r, dom_depth(useuse));
2146               }
2147             }
2148           }
2149           l -= uses_found;    // we deleted 1 or more copies of this edge
2150         }
2151 
2152         // Now finish up 'r'
2153         r->set_req( 1, newuse );
2154         r->set_req( 2,    use );
2155         _igvn.register_new_node_with_optimizer(r);
2156         set_loop(r, use_loop);
2157         set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
2158       } // End of if a loop-exit test
2159     }
2160   }
2161 
2162   // Step 4: If loop-invariant use is not control, it must be dominated by a
2163   // loop exit IfFalse/IfTrue.  Find "proper" loop exit.  Make a Region
2164   // there if needed.  Make a Phi there merging old and new used values.
2165   Node_List *split_if_set = NULL;
2166   Node_List *split_bool_set = NULL;
2167   Node_List *split_cex_set = NULL;
2168   for( i = 0; i < loop->_body.size(); i++ ) {
2169     Node* old = loop->_body.at(i);
2170     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2171                                 split_bool_set, split_cex_set, worklist, new_counter,
2172                                 mode);
2173   }
2174 
2175   for (i = 0; i < extra_data_nodes.size(); i++) {
2176     Node* old = extra_data_nodes.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   // Check for IFs that need splitting/cloning.  Happens if an IF outside of
2183   // the loop uses a condition set in the loop.  The original IF probably
2184   // takes control from one or more OLD Regions (which in turn get from NEW
2185   // Regions).  In any case, there will be a set of Phis for each merge point
2186   // from the IF up to where the original BOOL def exists the loop.
2187   if (split_if_set) {
2188     while (split_if_set->size()) {
2189       Node *iff = split_if_set->pop();
2190       if (iff->in(1)->is_Phi()) {
2191         Node *b = clone_iff(iff->in(1)->as_Phi(), loop);
2192         _igvn.replace_input_of(iff, 1, b);
2193       }
2194     }
2195   }
2196   if (split_bool_set) {
2197     while (split_bool_set->size()) {
2198       Node *b = split_bool_set->pop();
2199       Node *phi = b->in(1);
2200       assert(phi->is_Phi(), "");
2201       CmpNode *cmp = clone_bool((PhiNode*)phi, loop);
2202       _igvn.replace_input_of(b, 1, cmp);
2203     }
2204   }
2205   if (split_cex_set) {
2206     while (split_cex_set->size()) {
2207       Node *b = split_cex_set->pop();
2208       assert(b->in(0)->is_Region(), "");
2209       assert(b->in(1)->is_Phi(), "");
2210       assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2211       split_up(b, b->in(0), NULL);
2212     }
2213   }
2214 
2215 }
2216 
2217 
2218 //---------------------- stride_of_possible_iv -------------------------------------
2219 // Looks for an iff/bool/comp with one operand of the compare
2220 // being a cycle involving an add and a phi,
2221 // with an optional truncation (left-shift followed by a right-shift)
2222 // of the add. Returns zero if not an iv.
2223 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2224   Node* trunc1 = NULL;
2225   Node* trunc2 = NULL;
2226   const TypeInt* ttype = NULL;
2227   if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
2228     return 0;
2229   }
2230   BoolNode* bl = iff->in(1)->as_Bool();
2231   Node* cmp = bl->in(1);
2232   if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2233     return 0;
2234   }
2235   // Must have an invariant operand
2236   if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2237     return 0;
2238   }
2239   Node* add2 = NULL;
2240   Node* cmp1 = cmp->in(1);
2241   if (cmp1->is_Phi()) {
2242     // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2243     Node* phi = cmp1;
2244     for (uint i = 1; i < phi->req(); i++) {
2245       Node* in = phi->in(i);
2246       Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2247                                 &trunc1, &trunc2, &ttype);
2248       if (add && add->in(1) == phi) {
2249         add2 = add->in(2);
2250         break;
2251       }
2252     }
2253   } else {
2254     // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2255     Node* addtrunc = cmp1;
2256     Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2257                                 &trunc1, &trunc2, &ttype);
2258     if (add && add->in(1)->is_Phi()) {
2259       Node* phi = add->in(1);
2260       for (uint i = 1; i < phi->req(); i++) {
2261         if (phi->in(i) == addtrunc) {
2262           add2 = add->in(2);
2263           break;
2264         }
2265       }
2266     }
2267   }
2268   if (add2 != NULL) {
2269     const TypeInt* add2t = _igvn.type(add2)->is_int();
2270     if (add2t->is_con()) {
2271       return add2t->get_con();
2272     }
2273   }
2274   return 0;
2275 }
2276 
2277 
2278 //---------------------- stay_in_loop -------------------------------------
2279 // Return the (unique) control output node that's in the loop (if it exists.)
2280 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2281   Node* unique = NULL;
2282   if (!n) return NULL;
2283   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2284     Node* use = n->fast_out(i);
2285     if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2286       if (unique != NULL) {
2287         return NULL;
2288       }
2289       unique = use;
2290     }
2291   }
2292   return unique;
2293 }
2294 
2295 //------------------------------ register_node -------------------------------------
2296 // Utility to register node "n" with PhaseIdealLoop
2297 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
2298   _igvn.register_new_node_with_optimizer(n);
2299   loop->_body.push(n);
2300   if (n->is_CFG()) {
2301     set_loop(n, loop);
2302     set_idom(n, pred, ddepth);
2303   } else {
2304     set_ctrl(n, pred);
2305   }
2306 }
2307 
2308 //------------------------------ proj_clone -------------------------------------
2309 // Utility to create an if-projection
2310 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2311   ProjNode* c = p->clone()->as_Proj();
2312   c->set_req(0, iff);
2313   return c;
2314 }
2315 
2316 //------------------------------ short_circuit_if -------------------------------------
2317 // Force the iff control output to be the live_proj
2318 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2319   guarantee(live_proj != NULL, "null projection");
2320   int proj_con = live_proj->_con;
2321   assert(proj_con == 0 || proj_con == 1, "false or true projection");
2322   Node *con = _igvn.intcon(proj_con);
2323   set_ctrl(con, C->root());
2324   if (iff) {
2325     iff->set_req(1, con);
2326   }
2327   return con;
2328 }
2329 
2330 //------------------------------ insert_if_before_proj -------------------------------------
2331 // Insert a new if before an if projection (* - new node)
2332 //
2333 // before
2334 //           if(test)
2335 //           /     \
2336 //          v       v
2337 //    other-proj   proj (arg)
2338 //
2339 // after
2340 //           if(test)
2341 //           /     \
2342 //          /       v
2343 //         |      * proj-clone
2344 //         v          |
2345 //    other-proj      v
2346 //                * new_if(relop(cmp[IU](left,right)))
2347 //                  /  \
2348 //                 v    v
2349 //         * new-proj  proj
2350 //         (returned)
2351 //
2352 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2353   IfNode* iff = proj->in(0)->as_If();
2354   IdealLoopTree *loop = get_loop(proj);
2355   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2356   int ddepth = dom_depth(proj);
2357 
2358   _igvn.rehash_node_delayed(iff);
2359   _igvn.rehash_node_delayed(proj);
2360 
2361   proj->set_req(0, NULL);  // temporary disconnect
2362   ProjNode* proj2 = proj_clone(proj, iff);
2363   register_node(proj2, loop, iff, ddepth);
2364 
2365   Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2366   register_node(cmp, loop, proj2, ddepth);
2367 
2368   BoolNode* bol = new BoolNode(cmp, relop);
2369   register_node(bol, loop, proj2, ddepth);
2370 
2371   int opcode = iff->Opcode();
2372   assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2373   IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2374     new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2375   register_node(new_if, loop, proj2, ddepth);
2376 
2377   proj->set_req(0, new_if); // reattach
2378   set_idom(proj, new_if, ddepth);
2379 
2380   ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2381   guarantee(new_exit != NULL, "null exit node");
2382   register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2383 
2384   return new_exit;
2385 }
2386 
2387 //------------------------------ insert_region_before_proj -------------------------------------
2388 // Insert a region before an if projection (* - new node)
2389 //
2390 // before
2391 //           if(test)
2392 //          /      |
2393 //         v       |
2394 //       proj      v
2395 //               other-proj
2396 //
2397 // after
2398 //           if(test)
2399 //          /      |
2400 //         v       |
2401 // * proj-clone    v
2402 //         |     other-proj
2403 //         v
2404 // * new-region
2405 //         |
2406 //         v
2407 // *      dum_if
2408 //       /     \
2409 //      v       \
2410 // * dum-proj    v
2411 //              proj
2412 //
2413 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2414   IfNode* iff = proj->in(0)->as_If();
2415   IdealLoopTree *loop = get_loop(proj);
2416   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2417   int ddepth = dom_depth(proj);
2418 
2419   _igvn.rehash_node_delayed(iff);
2420   _igvn.rehash_node_delayed(proj);
2421 
2422   proj->set_req(0, NULL);  // temporary disconnect
2423   ProjNode* proj2 = proj_clone(proj, iff);
2424   register_node(proj2, loop, iff, ddepth);
2425 
2426   RegionNode* reg = new RegionNode(2);
2427   reg->set_req(1, proj2);
2428   register_node(reg, loop, iff, ddepth);
2429 
2430   IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2431   register_node(dum_if, loop, reg, ddepth);
2432 
2433   proj->set_req(0, dum_if); // reattach
2434   set_idom(proj, dum_if, ddepth);
2435 
2436   ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2437   register_node(dum_proj, loop, dum_if, ddepth);
2438 
2439   return reg;
2440 }
2441 
2442 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2443 // Clone a signed compare loop exit from an unsigned compare and
2444 // insert it before the unsigned cmp on the stay-in-loop path.
2445 // All new nodes inserted in the dominator tree between the original
2446 // if and it's projections.  The original if test is replaced with
2447 // a constant to force the stay-in-loop path.
2448 //
2449 // This is done to make sure that the original if and it's projections
2450 // still dominate the same set of control nodes, that the ctrl() relation
2451 // from data nodes to them is preserved, and that their loop nesting is
2452 // preserved.
2453 //
2454 // before
2455 //          if(i <u limit)    unsigned compare loop exit
2456 //         /       |
2457 //        v        v
2458 //   exit-proj   stay-in-loop-proj
2459 //
2460 // after
2461 //          if(stay-in-loop-const)  original if
2462 //         /       |
2463 //        /        v
2464 //       /  if(i <  limit)    new signed test
2465 //      /  /       |
2466 //     /  /        v
2467 //    /  /  if(i <u limit)    new cloned unsigned test
2468 //   /  /   /      |
2469 //   v  v  v       |
2470 //    region       |
2471 //        |        |
2472 //      dum-if     |
2473 //     /  |        |
2474 // ether  |        |
2475 //        v        v
2476 //   exit-proj   stay-in-loop-proj
2477 //
2478 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2479   const bool Signed   = true;
2480   const bool Unsigned = false;
2481 
2482   BoolNode* bol = if_cmpu->in(1)->as_Bool();
2483   if (bol->_test._test != BoolTest::lt) return NULL;
2484   CmpNode* cmpu = bol->in(1)->as_Cmp();
2485   if (cmpu->Opcode() != Op_CmpU) return NULL;
2486   int stride = stride_of_possible_iv(if_cmpu);
2487   if (stride == 0) return NULL;
2488 
2489   Node* lp_proj = stay_in_loop(if_cmpu, loop);
2490   guarantee(lp_proj != NULL, "null loop node");
2491 
2492   ProjNode* lp_continue = lp_proj->as_Proj();
2493   ProjNode* lp_exit     = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2494 
2495   Node* limit = NULL;
2496   if (stride > 0) {
2497     limit = cmpu->in(2);
2498   } else {
2499     limit = _igvn.makecon(TypeInt::ZERO);
2500     set_ctrl(limit, C->root());
2501   }
2502   // Create a new region on the exit path
2503   RegionNode* reg = insert_region_before_proj(lp_exit);
2504   guarantee(reg != NULL, "null region node");
2505 
2506   // Clone the if-cmpu-true-false using a signed compare
2507   BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2508   ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2509   reg->add_req(cmpi_exit);
2510 
2511   // Clone the if-cmpu-true-false
2512   BoolTest::mask rel_u = bol->_test._test;
2513   ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2514   reg->add_req(cmpu_exit);
2515 
2516   // Force original if to stay in loop.
2517   short_circuit_if(if_cmpu, lp_continue);
2518 
2519   return cmpi_exit->in(0)->as_If();
2520 }
2521 
2522 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2523 // Remove a previously inserted signed compare loop exit.
2524 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2525   Node* lp_proj = stay_in_loop(if_cmp, loop);
2526   assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2527          stay_in_loop(lp_proj, loop)->is_If() &&
2528          stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2529   Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2530   set_ctrl(con, C->root());
2531   if_cmp->set_req(1, con);
2532 }
2533 
2534 //------------------------------ scheduled_nodelist -------------------------------------
2535 // Create a post order schedule of nodes that are in the
2536 // "member" set.  The list is returned in "sched".
2537 // The first node in "sched" is the loop head, followed by
2538 // nodes which have no inputs in the "member" set, and then
2539 // followed by the nodes that have an immediate input dependence
2540 // on a node in "sched".
2541 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2542 
2543   assert(member.test(loop->_head->_idx), "loop head must be in member set");
2544   Arena *a = Thread::current()->resource_area();
2545   VectorSet visited(a);
2546   Node_Stack nstack(a, loop->_body.size());
2547 
2548   Node* n  = loop->_head;  // top of stack is cached in "n"
2549   uint idx = 0;
2550   visited.set(n->_idx);
2551 
2552   // Initially push all with no inputs from within member set
2553   for(uint i = 0; i < loop->_body.size(); i++ ) {
2554     Node *elt = loop->_body.at(i);
2555     if (member.test(elt->_idx)) {
2556       bool found = false;
2557       for (uint j = 0; j < elt->req(); j++) {
2558         Node* def = elt->in(j);
2559         if (def && member.test(def->_idx) && def != elt) {
2560           found = true;
2561           break;
2562         }
2563       }
2564       if (!found && elt != loop->_head) {
2565         nstack.push(n, idx);
2566         n = elt;
2567         assert(!visited.test(n->_idx), "not seen yet");
2568         visited.set(n->_idx);
2569       }
2570     }
2571   }
2572 
2573   // traverse out's that are in the member set
2574   while (true) {
2575     if (idx < n->outcnt()) {
2576       Node* use = n->raw_out(idx);
2577       idx++;
2578       if (!visited.test_set(use->_idx)) {
2579         if (member.test(use->_idx)) {
2580           nstack.push(n, idx);
2581           n = use;
2582           idx = 0;
2583         }
2584       }
2585     } else {
2586       // All outputs processed
2587       sched.push(n);
2588       if (nstack.is_empty()) break;
2589       n   = nstack.node();
2590       idx = nstack.index();
2591       nstack.pop();
2592     }
2593   }
2594 }
2595 
2596 
2597 //------------------------------ has_use_in_set -------------------------------------
2598 // Has a use in the vector set
2599 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2600   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2601     Node* use = n->fast_out(j);
2602     if (vset.test(use->_idx)) {
2603       return true;
2604     }
2605   }
2606   return false;
2607 }
2608 
2609 
2610 //------------------------------ has_use_internal_to_set -------------------------------------
2611 // Has use internal to the vector set (ie. not in a phi at the loop head)
2612 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2613   Node* head  = loop->_head;
2614   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2615     Node* use = n->fast_out(j);
2616     if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2617       return true;
2618     }
2619   }
2620   return false;
2621 }
2622 
2623 
2624 //------------------------------ clone_for_use_outside_loop -------------------------------------
2625 // clone "n" for uses that are outside of loop
2626 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2627   int cloned = 0;
2628   assert(worklist.size() == 0, "should be empty");
2629   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2630     Node* use = n->fast_out(j);
2631     if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2632       worklist.push(use);
2633     }
2634   }
2635   while( worklist.size() ) {
2636     Node *use = worklist.pop();
2637     if (!has_node(use) || use->in(0) == C->top()) continue;
2638     uint j;
2639     for (j = 0; j < use->req(); j++) {
2640       if (use->in(j) == n) break;
2641     }
2642     assert(j < use->req(), "must be there");
2643 
2644     // clone "n" and insert it between the inputs of "n" and the use outside the loop
2645     Node* n_clone = n->clone();
2646     _igvn.replace_input_of(use, j, n_clone);
2647     cloned++;
2648     Node* use_c;
2649     if (!use->is_Phi()) {
2650       use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2651     } else {
2652       // Use in a phi is considered a use in the associated predecessor block
2653       use_c = use->in(0)->in(j);
2654     }
2655     set_ctrl(n_clone, use_c);
2656     assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2657     get_loop(use_c)->_body.push(n_clone);
2658     _igvn.register_new_node_with_optimizer(n_clone);
2659 #ifndef PRODUCT
2660     if (TracePartialPeeling) {
2661       tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2662     }
2663 #endif
2664   }
2665   return cloned;
2666 }
2667 
2668 
2669 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2670 // clone "n" for special uses that are in the not_peeled region.
2671 // If these def-uses occur in separate blocks, the code generator
2672 // marks the method as not compilable.  For example, if a "BoolNode"
2673 // is in a different basic block than the "IfNode" that uses it, then
2674 // the compilation is aborted in the code generator.
2675 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2676                                                         VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2677   if (n->is_Phi() || n->is_Load()) {
2678     return;
2679   }
2680   assert(worklist.size() == 0, "should be empty");
2681   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2682     Node* use = n->fast_out(j);
2683     if ( not_peel.test(use->_idx) &&
2684          (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2685          use->in(1) == n)  {
2686       worklist.push(use);
2687     }
2688   }
2689   if (worklist.size() > 0) {
2690     // clone "n" and insert it between inputs of "n" and the use
2691     Node* n_clone = n->clone();
2692     loop->_body.push(n_clone);
2693     _igvn.register_new_node_with_optimizer(n_clone);
2694     set_ctrl(n_clone, get_ctrl(n));
2695     sink_list.push(n_clone);
2696     not_peel <<= n_clone->_idx;  // add n_clone to not_peel set.
2697 #ifndef PRODUCT
2698     if (TracePartialPeeling) {
2699       tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2700     }
2701 #endif
2702     while( worklist.size() ) {
2703       Node *use = worklist.pop();
2704       _igvn.rehash_node_delayed(use);
2705       for (uint j = 1; j < use->req(); j++) {
2706         if (use->in(j) == n) {
2707           use->set_req(j, n_clone);
2708         }
2709       }
2710     }
2711   }
2712 }
2713 
2714 
2715 //------------------------------ insert_phi_for_loop -------------------------------------
2716 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2717 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2718   Node *phi = PhiNode::make(lp, back_edge_val);
2719   phi->set_req(LoopNode::EntryControl, lp_entry_val);
2720   // Use existing phi if it already exists
2721   Node *hit = _igvn.hash_find_insert(phi);
2722   if( hit == NULL ) {
2723     _igvn.register_new_node_with_optimizer(phi);
2724     set_ctrl(phi, lp);
2725   } else {
2726     // Remove the new phi from the graph and use the hit
2727     _igvn.remove_dead_node(phi);
2728     phi = hit;
2729   }
2730   _igvn.replace_input_of(use, idx, phi);
2731 }
2732 
2733 #ifdef ASSERT
2734 //------------------------------ is_valid_loop_partition -------------------------------------
2735 // Validate the loop partition sets: peel and not_peel
2736 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2737                                               VectorSet& not_peel ) {
2738   uint i;
2739   // Check that peel_list entries are in the peel set
2740   for (i = 0; i < peel_list.size(); i++) {
2741     if (!peel.test(peel_list.at(i)->_idx)) {
2742       return false;
2743     }
2744   }
2745   // Check at loop members are in one of peel set or not_peel set
2746   for (i = 0; i < loop->_body.size(); i++ ) {
2747     Node *def  = loop->_body.at(i);
2748     uint di = def->_idx;
2749     // Check that peel set elements are in peel_list
2750     if (peel.test(di)) {
2751       if (not_peel.test(di)) {
2752         return false;
2753       }
2754       // Must be in peel_list also
2755       bool found = false;
2756       for (uint j = 0; j < peel_list.size(); j++) {
2757         if (peel_list.at(j)->_idx == di) {
2758           found = true;
2759           break;
2760         }
2761       }
2762       if (!found) {
2763         return false;
2764       }
2765     } else if (not_peel.test(di)) {
2766       if (peel.test(di)) {
2767         return false;
2768       }
2769     } else {
2770       return false;
2771     }
2772   }
2773   return true;
2774 }
2775 
2776 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2777 // Ensure a use outside of loop is of the right form
2778 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2779   Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2780   return (use->is_Phi() &&
2781           use_c->is_Region() && use_c->req() == 3 &&
2782           (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2783            use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2784            use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2785           loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2786 }
2787 
2788 //------------------------------ is_valid_clone_loop_form -------------------------------------
2789 // Ensure that all uses outside of loop are of the right form
2790 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2791                                                uint orig_exit_idx, uint clone_exit_idx) {
2792   uint len = peel_list.size();
2793   for (uint i = 0; i < len; i++) {
2794     Node *def = peel_list.at(i);
2795 
2796     for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2797       Node *use = def->fast_out(j);
2798       Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2799       if (!loop->is_member(get_loop(use_c))) {
2800         // use is not in the loop, check for correct structure
2801         if (use->in(0) == def) {
2802           // Okay
2803         } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2804           return false;
2805         }
2806       }
2807     }
2808   }
2809   return true;
2810 }
2811 #endif
2812 
2813 //------------------------------ partial_peel -------------------------------------
2814 // Partially peel (aka loop rotation) the top portion of a loop (called
2815 // the peel section below) by cloning it and placing one copy just before
2816 // the new loop head and the other copy at the bottom of the new loop.
2817 //
2818 //    before                       after                where it came from
2819 //
2820 //    stmt1                        stmt1
2821 //  loop:                          stmt2                     clone
2822 //    stmt2                        if condA goto exitA       clone
2823 //    if condA goto exitA        new_loop:                   new
2824 //    stmt3                        stmt3                     clone
2825 //    if !condB goto loop          if condB goto exitB       clone
2826 //  exitB:                         stmt2                     orig
2827 //    stmt4                        if !condA goto new_loop   orig
2828 //  exitA:                         goto exitA
2829 //                               exitB:
2830 //                                 stmt4
2831 //                               exitA:
2832 //
2833 // Step 1: find the cut point: an exit test on probable
2834 //         induction variable.
2835 // Step 2: schedule (with cloning) operations in the peel
2836 //         section that can be executed after the cut into
2837 //         the section that is not peeled.  This may need
2838 //         to clone operations into exit blocks.  For
2839 //         instance, a reference to A[i] in the not-peel
2840 //         section and a reference to B[i] in an exit block
2841 //         may cause a left-shift of i by 2 to be placed
2842 //         in the peel block.  This step will clone the left
2843 //         shift into the exit block and sink the left shift
2844 //         from the peel to the not-peel section.
2845 // Step 3: clone the loop, retarget the control, and insert
2846 //         phis for values that are live across the new loop
2847 //         head.  This is very dependent on the graph structure
2848 //         from clone_loop.  It creates region nodes for
2849 //         exit control and associated phi nodes for values
2850 //         flow out of the loop through that exit.  The region
2851 //         node is dominated by the clone's control projection.
2852 //         So the clone's peel section is placed before the
2853 //         new loop head, and the clone's not-peel section is
2854 //         forms the top part of the new loop.  The original
2855 //         peel section forms the tail of the new loop.
2856 // Step 4: update the dominator tree and recompute the
2857 //         dominator depth.
2858 //
2859 //                   orig
2860 //
2861 //                   stmt1
2862 //                     |
2863 //                     v
2864 //               loop predicate
2865 //                     |
2866 //                     v
2867 //                   loop<----+
2868 //                     |      |
2869 //                   stmt2    |
2870 //                     |      |
2871 //                     v      |
2872 //                    ifA     |
2873 //                   / |      |
2874 //                  v  v      |
2875 //               false true   ^  <-- last_peel
2876 //               /     |      |
2877 //              /   ===|==cut |
2878 //             /     stmt3    |  <-- first_not_peel
2879 //            /        |      |
2880 //            |        v      |
2881 //            v       ifB     |
2882 //          exitA:   / \      |
2883 //                  /   \     |
2884 //                 v     v    |
2885 //               false true   |
2886 //               /       \    |
2887 //              /         ----+
2888 //             |
2889 //             v
2890 //           exitB:
2891 //           stmt4
2892 //
2893 //
2894 //            after clone loop
2895 //
2896 //                   stmt1
2897 //                     |
2898 //                     v
2899 //               loop predicate
2900 //                 /       \
2901 //        clone   /         \   orig
2902 //               /           \
2903 //              /             \
2904 //             v               v
2905 //   +---->loop                loop<----+
2906 //   |      |                    |      |
2907 //   |    stmt2                stmt2    |
2908 //   |      |                    |      |
2909 //   |      v                    v      |
2910 //   |      ifA                 ifA     |
2911 //   |      | \                / |      |
2912 //   |      v  v              v  v      |
2913 //   ^    true  false      false true   ^  <-- last_peel
2914 //   |      |   ^   \       /    |      |
2915 //   | cut==|==  \   \     /  ===|==cut |
2916 //   |    stmt3   \   \   /    stmt3    |  <-- first_not_peel
2917 //   |      |    dom   | |       |      |
2918 //   |      v      \  1v v2      v      |
2919 //   |      ifB     regionA     ifB     |
2920 //   |      / \        |       / \      |
2921 //   |     /   \       v      /   \     |
2922 //   |    v     v    exitA:  v     v    |
2923 //   |    true  false      false true   |
2924 //   |    /     ^   \      /       \    |
2925 //   +----       \   \    /         ----+
2926 //               dom  \  /
2927 //                 \  1v v2
2928 //                  regionB
2929 //                     |
2930 //                     v
2931 //                   exitB:
2932 //                   stmt4
2933 //
2934 //
2935 //           after partial peel
2936 //
2937 //                  stmt1
2938 //                     |
2939 //                     v
2940 //               loop predicate
2941 //                 /
2942 //        clone   /             orig
2943 //               /          TOP
2944 //              /             \
2945 //             v               v
2946 //    TOP->loop                loop----+
2947 //          |                    |      |
2948 //        stmt2                stmt2    |
2949 //          |                    |      |
2950 //          v                    v      |
2951 //          ifA                 ifA     |
2952 //          | \                / |      |
2953 //          v  v              v  v      |
2954 //        true  false      false true   |     <-- last_peel
2955 //          |   ^   \       /    +------|---+
2956 //  +->newloop   \   \     /  === ==cut |   |
2957 //  |     stmt3   \   \   /     TOP     |   |
2958 //  |       |    dom   | |      stmt3   |   | <-- first_not_peel
2959 //  |       v      \  1v v2      v      |   |
2960 //  |       ifB     regionA     ifB     ^   v
2961 //  |       / \        |       / \      |   |
2962 //  |      /   \       v      /   \     |   |
2963 //  |     v     v    exitA:  v     v    |   |
2964 //  |     true  false      false true   |   |
2965 //  |     /     ^   \      /       \    |   |
2966 //  |    |       \   \    /         v   |   |
2967 //  |    |       dom  \  /         TOP  |   |
2968 //  |    |         \  1v v2             |   |
2969 //  ^    v          regionB             |   |
2970 //  |    |             |                |   |
2971 //  |    |             v                ^   v
2972 //  |    |           exitB:             |   |
2973 //  |    |           stmt4              |   |
2974 //  |    +------------>-----------------+   |
2975 //  |                                       |
2976 //  +-----------------<---------------------+
2977 //
2978 //
2979 //              final graph
2980 //
2981 //                  stmt1
2982 //                    |
2983 //                    v
2984 //               loop predicate
2985 //                    |
2986 //                    v
2987 //                  stmt2 clone
2988 //                    |
2989 //                    v
2990 //         ........> ifA clone
2991 //         :        / |
2992 //        dom      /  |
2993 //         :      v   v
2994 //         :  false   true
2995 //         :  |       |
2996 //         :  |       v
2997 //         :  |    newloop<-----+
2998 //         :  |        |        |
2999 //         :  |     stmt3 clone |
3000 //         :  |        |        |
3001 //         :  |        v        |
3002 //         :  |       ifB       |
3003 //         :  |      / \        |
3004 //         :  |     v   v       |
3005 //         :  |  false true     |
3006 //         :  |   |     |       |
3007 //         :  |   v    stmt2    |
3008 //         :  | exitB:  |       |
3009 //         :  | stmt4   v       |
3010 //         :  |       ifA orig  |
3011 //         :  |      /  \       |
3012 //         :  |     /    \      |
3013 //         :  |    v     v      |
3014 //         :  |  false  true    |
3015 //         :  |  /        \     |
3016 //         :  v  v         -----+
3017 //          RegionA
3018 //             |
3019 //             v
3020 //           exitA
3021 //
3022 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3023 
3024   assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3025   if (!loop->_head->is_Loop()) {
3026     return false;
3027   }
3028   LoopNode *head = loop->_head->as_Loop();
3029 
3030   if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3031     return false;
3032   }
3033 
3034   // Check for complex exit control
3035   for (uint ii = 0; ii < loop->_body.size(); ii++) {
3036     Node *n = loop->_body.at(ii);
3037     int opc = n->Opcode();
3038     if (n->is_Call()        ||
3039         opc == Op_Catch     ||
3040         opc == Op_CatchProj ||
3041         opc == Op_Jump      ||
3042         opc == Op_JumpProj) {
3043 #ifndef PRODUCT
3044       if (TracePartialPeeling) {
3045         tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3046       }
3047 #endif
3048       return false;
3049     }
3050   }
3051 
3052   int dd = dom_depth(head);
3053 
3054   // Step 1: find cut point
3055 
3056   // Walk up dominators to loop head looking for first loop exit
3057   // which is executed on every path thru loop.
3058   IfNode *peel_if = NULL;
3059   IfNode *peel_if_cmpu = NULL;
3060 
3061   Node *iff = loop->tail();
3062   while (iff != head) {
3063     if (iff->is_If()) {
3064       Node *ctrl = get_ctrl(iff->in(1));
3065       if (ctrl->is_top()) return false; // Dead test on live IF.
3066       // If loop-varying exit-test, check for induction variable
3067       if (loop->is_member(get_loop(ctrl)) &&
3068           loop->is_loop_exit(iff) &&
3069           is_possible_iv_test(iff)) {
3070         Node* cmp = iff->in(1)->in(1);
3071         if (cmp->Opcode() == Op_CmpI) {
3072           peel_if = iff->as_If();
3073         } else {
3074           assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3075           peel_if_cmpu = iff->as_If();
3076         }
3077       }
3078     }
3079     iff = idom(iff);
3080   }
3081 
3082   // Prefer signed compare over unsigned compare.
3083   IfNode* new_peel_if = NULL;
3084   if (peel_if == NULL) {
3085     if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
3086       return false;   // No peel point found
3087     }
3088     new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3089     if (new_peel_if == NULL) {
3090       return false;   // No peel point found
3091     }
3092     peel_if = new_peel_if;
3093   }
3094   Node* last_peel        = stay_in_loop(peel_if, loop);
3095   Node* first_not_peeled = stay_in_loop(last_peel, loop);
3096   if (first_not_peeled == NULL || first_not_peeled == head) {
3097     return false;
3098   }
3099 
3100 #ifndef PRODUCT
3101   if (TraceLoopOpts) {
3102     tty->print("PartialPeel  ");
3103     loop->dump_head();
3104   }
3105 
3106   if (TracePartialPeeling) {
3107     tty->print_cr("before partial peel one iteration");
3108     Node_List wl;
3109     Node* t = head->in(2);
3110     while (true) {
3111       wl.push(t);
3112       if (t == head) break;
3113       t = idom(t);
3114     }
3115     while (wl.size() > 0) {
3116       Node* tt = wl.pop();
3117       tt->dump();
3118       if (tt == last_peel) tty->print_cr("-- cut --");
3119     }
3120   }
3121 #endif
3122   ResourceArea *area = Thread::current()->resource_area();
3123   VectorSet peel(area);
3124   VectorSet not_peel(area);
3125   Node_List peel_list(area);
3126   Node_List worklist(area);
3127   Node_List sink_list(area);
3128 
3129   if (!may_require_nodes(loop->est_loop_clone_sz(2))) {
3130     return false;
3131   }
3132 
3133   // Set of cfg nodes to peel are those that are executable from
3134   // the head through last_peel.
3135   assert(worklist.size() == 0, "should be empty");
3136   worklist.push(head);
3137   peel.set(head->_idx);
3138   while (worklist.size() > 0) {
3139     Node *n = worklist.pop();
3140     if (n != last_peel) {
3141       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3142         Node* use = n->fast_out(j);
3143         if (use->is_CFG() &&
3144             loop->is_member(get_loop(use)) &&
3145             !peel.test_set(use->_idx)) {
3146           worklist.push(use);
3147         }
3148       }
3149     }
3150   }
3151 
3152   // Set of non-cfg nodes to peel are those that are control
3153   // dependent on the cfg nodes.
3154   uint i;
3155   for(i = 0; i < loop->_body.size(); i++ ) {
3156     Node *n = loop->_body.at(i);
3157     Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3158     if (peel.test(n_c->_idx)) {
3159       peel.set(n->_idx);
3160     } else {
3161       not_peel.set(n->_idx);
3162     }
3163   }
3164 
3165   // Step 2: move operations from the peeled section down into the
3166   //         not-peeled section
3167 
3168   // Get a post order schedule of nodes in the peel region
3169   // Result in right-most operand.
3170   scheduled_nodelist(loop, peel, peel_list );
3171 
3172   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3173 
3174   // For future check for too many new phis
3175   uint old_phi_cnt = 0;
3176   for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3177     Node* use = head->fast_out(j);
3178     if (use->is_Phi()) old_phi_cnt++;
3179   }
3180 
3181 #ifndef PRODUCT
3182   if (TracePartialPeeling) {
3183     tty->print_cr("\npeeled list");
3184   }
3185 #endif
3186 
3187   // Evacuate nodes in peel region into the not_peeled region if possible
3188   uint new_phi_cnt = 0;
3189   uint cloned_for_outside_use = 0;
3190   for (i = 0; i < peel_list.size();) {
3191     Node* n = peel_list.at(i);
3192 #ifndef PRODUCT
3193   if (TracePartialPeeling) n->dump();
3194 #endif
3195     bool incr = true;
3196     if ( !n->is_CFG() ) {
3197 
3198       if ( has_use_in_set(n, not_peel) ) {
3199 
3200         // If not used internal to the peeled region,
3201         // move "n" from peeled to not_peeled region.
3202 
3203         if ( !has_use_internal_to_set(n, peel, loop) ) {
3204 
3205           // if not pinned and not a load (which maybe anti-dependent on a store)
3206           // and not a CMove (Matcher expects only bool->cmove).
3207           if (n->in(0) == NULL && !n->is_Load() && !n->is_CMove()) {
3208             cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
3209             sink_list.push(n);
3210             peel     >>= n->_idx; // delete n from peel set.
3211             not_peel <<= n->_idx; // add n to not_peel set.
3212             peel_list.remove(i);
3213             incr = false;
3214 #ifndef PRODUCT
3215             if (TracePartialPeeling) {
3216               tty->print_cr("sink to not_peeled region: %d newbb: %d",
3217                             n->_idx, get_ctrl(n)->_idx);
3218             }
3219 #endif
3220           }
3221         } else {
3222           // Otherwise check for special def-use cases that span
3223           // the peel/not_peel boundary such as bool->if
3224           clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
3225           new_phi_cnt++;
3226         }
3227       }
3228     }
3229     if (incr) i++;
3230   }
3231 
3232   if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
3233 #ifndef PRODUCT
3234     if (TracePartialPeeling) {
3235       tty->print_cr("\nToo many new phis: %d  old %d new cmpi: %c",
3236                     new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
3237     }
3238 #endif
3239     if (new_peel_if != NULL) {
3240       remove_cmpi_loop_exit(new_peel_if, loop);
3241     }
3242     // Inhibit more partial peeling on this loop
3243     assert(!head->is_partial_peel_loop(), "not partial peeled");
3244     head->mark_partial_peel_failed();
3245     if (cloned_for_outside_use > 0) {
3246       // Terminate this round of loop opts because
3247       // the graph outside this loop was changed.
3248       C->set_major_progress();
3249       return true;
3250     }
3251     return false;
3252   }
3253 
3254   // Step 3: clone loop, retarget control, and insert new phis
3255 
3256   // Create new loop head for new phis and to hang
3257   // the nodes being moved (sinked) from the peel region.
3258   LoopNode* new_head = new LoopNode(last_peel, last_peel);
3259   new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3260   _igvn.register_new_node_with_optimizer(new_head);
3261   assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3262   _igvn.replace_input_of(first_not_peeled, 0, new_head);
3263   set_loop(new_head, loop);
3264   loop->_body.push(new_head);
3265   not_peel.set(new_head->_idx);
3266   set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3267   set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
3268 
3269   while (sink_list.size() > 0) {
3270     Node* n = sink_list.pop();
3271     set_ctrl(n, new_head);
3272   }
3273 
3274   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3275 
3276   clone_loop(loop, old_new, dd, IgnoreStripMined);
3277 
3278   const uint clone_exit_idx = 1;
3279   const uint orig_exit_idx  = 2;
3280   assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
3281 
3282   Node* head_clone             = old_new[head->_idx];
3283   LoopNode* new_head_clone     = old_new[new_head->_idx]->as_Loop();
3284   Node* orig_tail_clone        = head_clone->in(2);
3285 
3286   // Add phi if "def" node is in peel set and "use" is not
3287 
3288   for(i = 0; i < peel_list.size(); i++ ) {
3289     Node *def  = peel_list.at(i);
3290     if (!def->is_CFG()) {
3291       for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3292         Node *use = def->fast_out(j);
3293         if (has_node(use) && use->in(0) != C->top() &&
3294             (!peel.test(use->_idx) ||
3295              (use->is_Phi() && use->in(0) == head)) ) {
3296           worklist.push(use);
3297         }
3298       }
3299       while( worklist.size() ) {
3300         Node *use = worklist.pop();
3301         for (uint j = 1; j < use->req(); j++) {
3302           Node* n = use->in(j);
3303           if (n == def) {
3304 
3305             // "def" is in peel set, "use" is not in peel set
3306             // or "use" is in the entry boundary (a phi) of the peel set
3307 
3308             Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
3309 
3310             if ( loop->is_member(get_loop( use_c )) ) {
3311               // use is in loop
3312               if (old_new[use->_idx] != NULL) { // null for dead code
3313                 Node* use_clone = old_new[use->_idx];
3314                 _igvn.replace_input_of(use, j, C->top());
3315                 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
3316               }
3317             } else {
3318               assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
3319               // use is not in the loop, check if the live range includes the cut
3320               Node* lp_if = use_c->in(orig_exit_idx)->in(0);
3321               if (not_peel.test(lp_if->_idx)) {
3322                 assert(j == orig_exit_idx, "use from original loop");
3323                 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3324               }
3325             }
3326           }
3327         }
3328       }
3329     }
3330   }
3331 
3332   // Step 3b: retarget control
3333 
3334   // Redirect control to the new loop head if a cloned node in
3335   // the not_peeled region has control that points into the peeled region.
3336   // This necessary because the cloned peeled region will be outside
3337   // the loop.
3338   //                            from    to
3339   //          cloned-peeled    <---+
3340   //    new_head_clone:            |    <--+
3341   //          cloned-not_peeled  in(0)    in(0)
3342   //          orig-peeled
3343 
3344   for(i = 0; i < loop->_body.size(); i++ ) {
3345     Node *n = loop->_body.at(i);
3346     if (!n->is_CFG()           && n->in(0) != NULL        &&
3347         not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3348       Node* n_clone = old_new[n->_idx];
3349       _igvn.replace_input_of(n_clone, 0, new_head_clone);
3350     }
3351   }
3352 
3353   // Backedge of the surviving new_head (the clone) is original last_peel
3354   _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3355 
3356   // Cut first node in original not_peel set
3357   _igvn.rehash_node_delayed(new_head);                     // Multiple edge updates:
3358   new_head->set_req(LoopNode::EntryControl,    C->top());  //   use rehash_node_delayed / set_req instead of
3359   new_head->set_req(LoopNode::LoopBackControl, C->top());  //   multiple replace_input_of calls
3360 
3361   // Copy head_clone back-branch info to original head
3362   // and remove original head's loop entry and
3363   // clone head's back-branch
3364   _igvn.rehash_node_delayed(head); // Multiple edge updates
3365   head->set_req(LoopNode::EntryControl,    head_clone->in(LoopNode::LoopBackControl));
3366   head->set_req(LoopNode::LoopBackControl, C->top());
3367   _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3368 
3369   // Similarly modify the phis
3370   for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3371     Node* use = head->fast_out(k);
3372     if (use->is_Phi() && use->outcnt() > 0) {
3373       Node* use_clone = old_new[use->_idx];
3374       _igvn.rehash_node_delayed(use); // Multiple edge updates
3375       use->set_req(LoopNode::EntryControl,    use_clone->in(LoopNode::LoopBackControl));
3376       use->set_req(LoopNode::LoopBackControl, C->top());
3377       _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3378     }
3379   }
3380 
3381   // Step 4: update dominator tree and dominator depth
3382 
3383   set_idom(head, orig_tail_clone, dd);
3384   recompute_dom_depth();
3385 
3386   // Inhibit more partial peeling on this loop
3387   new_head_clone->set_partial_peel_loop();
3388   C->set_major_progress();
3389   loop->record_for_igvn();
3390 
3391 #ifndef PRODUCT
3392   if (TracePartialPeeling) {
3393     tty->print_cr("\nafter partial peel one iteration");
3394     Node_List wl(area);
3395     Node* t = last_peel;
3396     while (true) {
3397       wl.push(t);
3398       if (t == head_clone) break;
3399       t = idom(t);
3400     }
3401     while (wl.size() > 0) {
3402       Node* tt = wl.pop();
3403       if (tt == head) tty->print_cr("orig head");
3404       else if (tt == new_head_clone) tty->print_cr("new head");
3405       else if (tt == head_clone) tty->print_cr("clone head");
3406       tt->dump();
3407     }
3408   }
3409 #endif
3410   return true;
3411 }
3412 
3413 //------------------------------reorg_offsets----------------------------------
3414 // Reorganize offset computations to lower register pressure.  Mostly
3415 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3416 // then alive with the post-incremented trip counter forcing an extra
3417 // register move)
3418 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3419   // Perform it only for canonical counted loops.
3420   // Loop's shape could be messed up by iteration_split_impl.
3421   if (!loop->_head->is_CountedLoop())
3422     return;
3423   if (!loop->_head->as_Loop()->is_valid_counted_loop())
3424     return;
3425 
3426   CountedLoopNode *cl = loop->_head->as_CountedLoop();
3427   CountedLoopEndNode *cle = cl->loopexit();
3428   Node *exit = cle->proj_out(false);
3429   Node *phi = cl->phi();
3430 
3431   // Check for the special case when using the pre-incremented trip-counter on
3432   // the fall-out  path (forces the pre-incremented  and post-incremented trip
3433   // counter to be live  at the same time).  Fix this by  adjusting to use the
3434   // post-increment trip counter.
3435 
3436   bool progress = true;
3437   while (progress) {
3438     progress = false;
3439     for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3440       Node* use = phi->fast_out(i);   // User of trip-counter
3441       if (!has_ctrl(use))  continue;
3442       Node *u_ctrl = get_ctrl(use);
3443       if (use->is_Phi()) {
3444         u_ctrl = NULL;
3445         for (uint j = 1; j < use->req(); j++)
3446           if (use->in(j) == phi)
3447             u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3448       }
3449       IdealLoopTree *u_loop = get_loop(u_ctrl);
3450       // Look for loop-invariant use
3451       if (u_loop == loop) continue;
3452       if (loop->is_member(u_loop)) continue;
3453       // Check that use is live out the bottom.  Assuming the trip-counter
3454       // update is right at the bottom, uses of of the loop middle are ok.
3455       if (dom_lca(exit, u_ctrl) != exit) continue;
3456       // Hit!  Refactor use to use the post-incremented tripcounter.
3457       // Compute a post-increment tripcounter.
3458       Node* c = exit;
3459       if (cl->is_strip_mined()) {
3460         IdealLoopTree* outer_loop = get_loop(cl->outer_loop());
3461         if (!outer_loop->is_member(u_loop)) {
3462           c = cl->outer_loop_exit();
3463         }
3464       }
3465       Node *opaq = new Opaque2Node(C, cle->incr());
3466       register_new_node(opaq, c);
3467       Node *neg_stride = _igvn.intcon(-cle->stride_con());
3468       set_ctrl(neg_stride, C->root());
3469       Node *post = new AddINode(opaq, neg_stride);
3470       register_new_node(post, c);
3471       _igvn.rehash_node_delayed(use);
3472       for (uint j = 1; j < use->req(); j++) {
3473         if (use->in(j) == phi)
3474           use->set_req(j, post);
3475       }
3476       // Since DU info changed, rerun loop
3477       progress = true;
3478       break;
3479     }
3480   }
3481 
3482 }