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.
1431             // I tried setting control edges on the x's to force them to
1432             // not combine, but the matching gets worried when it tries
1433             // to fold a StoreP and an AddP together (as part of an
1434             // address expression) and the AddP and StoreP have
1435             // different controls.
1436             if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1437           }
1438           _igvn.remove_dead_node(n);
1439         }
1440       }
1441     }
1442   }
1443 
1444   try_move_store_after_loop(n);
1445 
1446   // Check for Opaque2's who's loop has disappeared - who's input is in the
1447   // same loop nest as their output.  Remove 'em, they are no longer useful.
1448   if( n_op == Op_Opaque2 &&
1449       n->in(1) != NULL &&
1450       get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1451     _igvn.replace_node( n, n->in(1) );
1452   }
1453 }
1454 
1455 //------------------------------split_if_with_blocks---------------------------
1456 // Check for aggressive application of 'split-if' optimization,
1457 // using basic block level info.
1458 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1459   Node* root = C->root();
1460   visited.set(root->_idx); // first, mark root as visited
1461   // Do pre-visit work for root
1462   Node* n   = split_if_with_blocks_pre(root);
1463   uint  cnt = n->outcnt();
1464   uint  i   = 0;
1465 
1466   while (true) {
1467     // Visit all children
1468     if (i < cnt) {
1469       Node* use = n->raw_out(i);
1470       ++i;
1471       if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1472         // Now do pre-visit work for this use
1473         use = split_if_with_blocks_pre(use);
1474         nstack.push(n, i); // Save parent and next use's index.
1475         n   = use;         // Process all children of current use.
1476         cnt = use->outcnt();
1477         i   = 0;
1478       }
1479     }
1480     else {
1481       // All of n's children have been processed, complete post-processing.
1482       if (cnt != 0 && !n->is_Con()) {
1483         assert(has_node(n), "no dead nodes");
1484         split_if_with_blocks_post(n);
1485       }
1486       if (must_throttle_split_if()) {
1487         nstack.clear();
1488       }
1489       if (nstack.is_empty()) {
1490         // Finished all nodes on stack.
1491         break;
1492       }
1493       // Get saved parent node and next use's index. Visit the rest of uses.
1494       n   = nstack.node();
1495       cnt = n->outcnt();
1496       i   = nstack.index();
1497       nstack.pop();
1498     }
1499   }
1500 }
1501 
1502 
1503 //=============================================================================
1504 //
1505 //                   C L O N E   A   L O O P   B O D Y
1506 //
1507 
1508 //------------------------------clone_iff--------------------------------------
1509 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1510 // "Nearly" because all Nodes have been cloned from the original in the loop,
1511 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1512 // through the Phi recursively, and return a Bool.
1513 Node* PhaseIdealLoop::clone_iff(PhiNode *phi, IdealLoopTree *loop) {
1514 
1515   // Convert this Phi into a Phi merging Bools
1516   uint i;
1517   for (i = 1; i < phi->req(); i++) {
1518     Node *b = phi->in(i);
1519     if (b->is_Phi()) {
1520       _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi(), loop));
1521     } else {
1522       assert(b->is_Bool() || b->Opcode() == Op_Opaque4, "");
1523     }
1524   }
1525 
1526   Node* n = phi->in(1);
1527   Node* sample_opaque = NULL;
1528   Node *sample_bool = NULL;
1529   if (n->Opcode() == Op_Opaque4) {
1530     sample_opaque = n;
1531     sample_bool = n->in(1);
1532     assert(sample_bool->is_Bool(), "wrong type");
1533   } else {
1534     sample_bool = n;
1535   }
1536   Node *sample_cmp = sample_bool->in(1);
1537 
1538   // Make Phis to merge the Cmp's inputs.
1539   PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
1540   PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
1541   for (i = 1; i < phi->req(); i++) {
1542     Node *n1 = sample_opaque == NULL ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
1543     Node *n2 = sample_opaque == NULL ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
1544     phi1->set_req(i, n1);
1545     phi2->set_req(i, n2);
1546     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1547     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1548   }
1549   // See if these Phis have been made before.
1550   // Register with optimizer
1551   Node *hit1 = _igvn.hash_find_insert(phi1);
1552   if (hit1) {                   // Hit, toss just made Phi
1553     _igvn.remove_dead_node(phi1); // Remove new phi
1554     assert(hit1->is_Phi(), "" );
1555     phi1 = (PhiNode*)hit1;      // Use existing phi
1556   } else {                      // Miss
1557     _igvn.register_new_node_with_optimizer(phi1);
1558   }
1559   Node *hit2 = _igvn.hash_find_insert(phi2);
1560   if (hit2) {                   // Hit, toss just made Phi
1561     _igvn.remove_dead_node(phi2); // Remove new phi
1562     assert(hit2->is_Phi(), "" );
1563     phi2 = (PhiNode*)hit2;      // Use existing phi
1564   } else {                      // Miss
1565     _igvn.register_new_node_with_optimizer(phi2);
1566   }
1567   // Register Phis with loop/block info
1568   set_ctrl(phi1, phi->in(0));
1569   set_ctrl(phi2, phi->in(0));
1570   // Make a new Cmp
1571   Node *cmp = sample_cmp->clone();
1572   cmp->set_req(1, phi1);
1573   cmp->set_req(2, phi2);
1574   _igvn.register_new_node_with_optimizer(cmp);
1575   set_ctrl(cmp, phi->in(0));
1576 
1577   // Make a new Bool
1578   Node *b = sample_bool->clone();
1579   b->set_req(1,cmp);
1580   _igvn.register_new_node_with_optimizer(b);
1581   set_ctrl(b, phi->in(0));
1582 
1583   if (sample_opaque != NULL) {
1584     Node* opaque = sample_opaque->clone();
1585     opaque->set_req(1, b);
1586     _igvn.register_new_node_with_optimizer(opaque);
1587     set_ctrl(opaque, phi->in(0));
1588     return opaque;
1589   }
1590 
1591   assert(b->is_Bool(), "");
1592   return b;
1593 }
1594 
1595 //------------------------------clone_bool-------------------------------------
1596 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1597 // "Nearly" because all Nodes have been cloned from the original in the loop,
1598 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1599 // through the Phi recursively, and return a Bool.
1600 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1601   uint i;
1602   // Convert this Phi into a Phi merging Bools
1603   for( i = 1; i < phi->req(); i++ ) {
1604     Node *b = phi->in(i);
1605     if( b->is_Phi() ) {
1606       _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1607     } else {
1608       assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1609     }
1610   }
1611 
1612   Node *sample_cmp = phi->in(1);
1613 
1614   // Make Phis to merge the Cmp's inputs.
1615   PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1616   PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1617   for( uint j = 1; j < phi->req(); j++ ) {
1618     Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1619     Node *n1, *n2;
1620     if( cmp_top->is_Cmp() ) {
1621       n1 = cmp_top->in(1);
1622       n2 = cmp_top->in(2);
1623     } else {
1624       n1 = n2 = cmp_top;
1625     }
1626     phi1->set_req( j, n1 );
1627     phi2->set_req( j, n2 );
1628     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1629     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1630   }
1631 
1632   // See if these Phis have been made before.
1633   // Register with optimizer
1634   Node *hit1 = _igvn.hash_find_insert(phi1);
1635   if( hit1 ) {                  // Hit, toss just made Phi
1636     _igvn.remove_dead_node(phi1); // Remove new phi
1637     assert( hit1->is_Phi(), "" );
1638     phi1 = (PhiNode*)hit1;      // Use existing phi
1639   } else {                      // Miss
1640     _igvn.register_new_node_with_optimizer(phi1);
1641   }
1642   Node *hit2 = _igvn.hash_find_insert(phi2);
1643   if( hit2 ) {                  // Hit, toss just made Phi
1644     _igvn.remove_dead_node(phi2); // Remove new phi
1645     assert( hit2->is_Phi(), "" );
1646     phi2 = (PhiNode*)hit2;      // Use existing phi
1647   } else {                      // Miss
1648     _igvn.register_new_node_with_optimizer(phi2);
1649   }
1650   // Register Phis with loop/block info
1651   set_ctrl(phi1, phi->in(0));
1652   set_ctrl(phi2, phi->in(0));
1653   // Make a new Cmp
1654   Node *cmp = sample_cmp->clone();
1655   cmp->set_req( 1, phi1 );
1656   cmp->set_req( 2, phi2 );
1657   _igvn.register_new_node_with_optimizer(cmp);
1658   set_ctrl(cmp, phi->in(0));
1659 
1660   assert( cmp->is_Cmp(), "" );
1661   return (CmpNode*)cmp;
1662 }
1663 
1664 //------------------------------sink_use---------------------------------------
1665 // If 'use' was in the loop-exit block, it now needs to be sunk
1666 // below the post-loop merge point.
1667 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1668   if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1669     set_ctrl(use, post_loop);
1670     for (DUIterator j = use->outs(); use->has_out(j); j++)
1671       sink_use(use->out(j), post_loop);
1672   }
1673 }
1674 
1675 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1676                                                  IdealLoopTree* loop, IdealLoopTree* outer_loop,
1677                                                  Node_List*& split_if_set, Node_List*& split_bool_set,
1678                                                  Node_List*& split_cex_set, Node_List& worklist,
1679                                                  uint new_counter, CloneLoopMode mode) {
1680   Node* nnn = old_new[old->_idx];
1681   // Copy uses to a worklist, so I can munge the def-use info
1682   // with impunity.
1683   for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1684     worklist.push(old->fast_out(j));
1685 
1686   while( worklist.size() ) {
1687     Node *use = worklist.pop();
1688     if (!has_node(use))  continue; // Ignore dead nodes
1689     if (use->in(0) == C->top())  continue;
1690     IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1691     // Check for data-use outside of loop - at least one of OLD or USE
1692     // must not be a CFG node.
1693 #ifdef ASSERT
1694     if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == NULL) {
1695       Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
1696       assert(mode == ControlAroundStripMined && use == sfpt, "missed a node");
1697     }
1698 #endif
1699     if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
1700 
1701       // If the Data use is an IF, that means we have an IF outside of the
1702       // loop that is switching on a condition that is set inside of the
1703       // loop.  Happens if people set a loop-exit flag; then test the flag
1704       // in the loop to break the loop, then test is again outside of the
1705       // loop to determine which way the loop exited.
1706       // Loop predicate If node connects to Bool node through Opaque1 node.
1707       if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use) || use->Opcode() == Op_Opaque4) {
1708         // Since this code is highly unlikely, we lazily build the worklist
1709         // of such Nodes to go split.
1710         if (!split_if_set) {
1711           ResourceArea *area = Thread::current()->resource_area();
1712           split_if_set = new Node_List(area);
1713         }
1714         split_if_set->push(use);
1715       }
1716       if (use->is_Bool()) {
1717         if (!split_bool_set) {
1718           ResourceArea *area = Thread::current()->resource_area();
1719           split_bool_set = new Node_List(area);
1720         }
1721         split_bool_set->push(use);
1722       }
1723       if (use->Opcode() == Op_CreateEx) {
1724         if (!split_cex_set) {
1725           ResourceArea *area = Thread::current()->resource_area();
1726           split_cex_set = new Node_List(area);
1727         }
1728         split_cex_set->push(use);
1729       }
1730 
1731 
1732       // Get "block" use is in
1733       uint idx = 0;
1734       while( use->in(idx) != old ) idx++;
1735       Node *prev = use->is_CFG() ? use : get_ctrl(use);
1736       assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
1737       Node *cfg = prev->_idx >= new_counter
1738         ? prev->in(2)
1739         : idom(prev);
1740       if( use->is_Phi() )     // Phi use is in prior block
1741         cfg = prev->in(idx);  // NOT in block of Phi itself
1742       if (cfg->is_top()) {    // Use is dead?
1743         _igvn.replace_input_of(use, idx, C->top());
1744         continue;
1745       }
1746 
1747       // If use is referenced through control edge... (idx == 0)
1748       if (mode == IgnoreStripMined && idx == 0) {
1749         LoopNode *head = loop->_head->as_Loop();
1750         if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
1751           // That node is outside the inner loop, leave it outside the
1752           // outer loop as well to not confuse verification code.
1753           assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
1754           _igvn.replace_input_of(use, 0, head->outer_loop_exit());
1755           continue;
1756         }
1757       }
1758 
1759       while(!outer_loop->is_member(get_loop(cfg))) {
1760         prev = cfg;
1761         cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1762       }
1763       // If the use occurs after merging several exits from the loop, then
1764       // old value must have dominated all those exits.  Since the same old
1765       // value was used on all those exits we did not need a Phi at this
1766       // merge point.  NOW we do need a Phi here.  Each loop exit value
1767       // is now merged with the peeled body exit; each exit gets its own
1768       // private Phi and those Phis need to be merged here.
1769       Node *phi;
1770       if( prev->is_Region() ) {
1771         if( idx == 0 ) {      // Updating control edge?
1772           phi = prev;         // Just use existing control
1773         } else {              // Else need a new Phi
1774           phi = PhiNode::make( prev, old );
1775           // Now recursively fix up the new uses of old!
1776           for( uint i = 1; i < prev->req(); i++ ) {
1777             worklist.push(phi); // Onto worklist once for each 'old' input
1778           }
1779         }
1780       } else {
1781         // Get new RegionNode merging old and new loop exits
1782         prev = old_new[prev->_idx];
1783         assert( prev, "just made this in step 7" );
1784         if( idx == 0) {      // Updating control edge?
1785           phi = prev;         // Just use existing control
1786         } else {              // Else need a new Phi
1787           // Make a new Phi merging data values properly
1788           phi = PhiNode::make( prev, old );
1789           phi->set_req( 1, nnn );
1790         }
1791       }
1792       // If inserting a new Phi, check for prior hits
1793       if( idx != 0 ) {
1794         Node *hit = _igvn.hash_find_insert(phi);
1795         if( hit == NULL ) {
1796           _igvn.register_new_node_with_optimizer(phi); // Register new phi
1797         } else {                                      // or
1798           // Remove the new phi from the graph and use the hit
1799           _igvn.remove_dead_node(phi);
1800           phi = hit;                                  // Use existing phi
1801         }
1802         set_ctrl(phi, prev);
1803       }
1804       // Make 'use' use the Phi instead of the old loop body exit value
1805       _igvn.replace_input_of(use, idx, phi);
1806       if( use->_idx >= new_counter ) { // If updating new phis
1807         // Not needed for correctness, but prevents a weak assert
1808         // in AddPNode from tripping (when we end up with different
1809         // base & derived Phis that will become the same after
1810         // IGVN does CSE).
1811         Node *hit = _igvn.hash_find_insert(use);
1812         if( hit )             // Go ahead and re-hash for hits.
1813           _igvn.replace_node( use, hit );
1814       }
1815 
1816       // If 'use' was in the loop-exit block, it now needs to be sunk
1817       // below the post-loop merge point.
1818       sink_use( use, prev );
1819     }
1820   }
1821 }
1822 
1823 static void clone_outer_loop_helper(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
1824                                     const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
1825                                     bool check_old_new) {
1826   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1827     Node* u = n->fast_out(j);
1828     assert(check_old_new || old_new[u->_idx] == NULL, "shouldn't have been cloned");
1829     if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == NULL)) {
1830       Node* c = phase->get_ctrl(u);
1831       IdealLoopTree* u_loop = phase->get_loop(c);
1832       assert(!loop->is_member(u_loop), "can be in outer loop or out of both loops only");
1833       if (outer_loop->is_member(u_loop)) {
1834         wq.push(u);
1835       }
1836     }
1837   }
1838 }
1839 
1840 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1841                                       IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1842                                       Node_List& extra_data_nodes) {
1843   if (head->is_strip_mined() && mode != IgnoreStripMined) {
1844     CountedLoopNode* cl = head->as_CountedLoop();
1845     Node* l = cl->outer_loop();
1846     Node* tail = cl->outer_loop_tail();
1847     IfNode* le = cl->outer_loop_end();
1848     Node* sfpt = cl->outer_safepoint();
1849     CountedLoopEndNode* cle = cl->loopexit();
1850     CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
1851     CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
1852     Node* cle_out = cle->proj_out(false);
1853 
1854     Node* new_sfpt = NULL;
1855     Node* new_cle_out = cle_out->clone();
1856     old_new.map(cle_out->_idx, new_cle_out);
1857     if (mode == CloneIncludesStripMined) {
1858       // clone outer loop body
1859       Node* new_l = l->clone();
1860       Node* new_tail = tail->clone();
1861       IfNode* new_le = le->clone()->as_If();
1862       new_sfpt = sfpt->clone();
1863 
1864       set_loop(new_l, outer_loop->_parent);
1865       set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
1866       set_loop(new_cle_out, outer_loop->_parent);
1867       set_idom(new_cle_out, new_cle, dd);
1868       set_loop(new_sfpt, outer_loop->_parent);
1869       set_idom(new_sfpt, new_cle_out, dd);
1870       set_loop(new_le, outer_loop->_parent);
1871       set_idom(new_le, new_sfpt, dd);
1872       set_loop(new_tail, outer_loop->_parent);
1873       set_idom(new_tail, new_le, dd);
1874       set_idom(new_cl, new_l, dd);
1875 
1876       old_new.map(l->_idx, new_l);
1877       old_new.map(tail->_idx, new_tail);
1878       old_new.map(le->_idx, new_le);
1879       old_new.map(sfpt->_idx, new_sfpt);
1880 
1881       new_l->set_req(LoopNode::LoopBackControl, new_tail);
1882       new_l->set_req(0, new_l);
1883       new_tail->set_req(0, new_le);
1884       new_le->set_req(0, new_sfpt);
1885       new_sfpt->set_req(0, new_cle_out);
1886       new_cle_out->set_req(0, new_cle);
1887       new_cl->set_req(LoopNode::EntryControl, new_l);
1888 
1889       _igvn.register_new_node_with_optimizer(new_l);
1890       _igvn.register_new_node_with_optimizer(new_tail);
1891       _igvn.register_new_node_with_optimizer(new_le);
1892     } else {
1893       Node *newhead = old_new[loop->_head->_idx];
1894       newhead->as_Loop()->clear_strip_mined();
1895       _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
1896       set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1897     }
1898     // Look at data node that were assigned a control in the outer
1899     // loop: they are kept in the outer loop by the safepoint so start
1900     // from the safepoint node's inputs.
1901     IdealLoopTree* outer_loop = get_loop(l);
1902     Node_Stack stack(2);
1903     stack.push(sfpt, 1);
1904     uint new_counter = C->unique();
1905     while (stack.size() > 0) {
1906       Node* n = stack.node();
1907       uint i = stack.index();
1908       while (i < n->req() &&
1909              (n->in(i) == NULL ||
1910               !has_ctrl(n->in(i)) ||
1911               get_loop(get_ctrl(n->in(i))) != outer_loop ||
1912               (old_new[n->in(i)->_idx] != NULL && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
1913         i++;
1914       }
1915       if (i < n->req()) {
1916         stack.set_index(i+1);
1917         stack.push(n->in(i), 0);
1918       } else {
1919         assert(old_new[n->_idx] == NULL || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
1920         Node* m = n == sfpt ? new_sfpt : n->clone();
1921         if (m != NULL) {
1922           for (uint i = 0; i < n->req(); i++) {
1923             if (m->in(i) != NULL && old_new[m->in(i)->_idx] != NULL) {
1924               m->set_req(i, old_new[m->in(i)->_idx]);
1925             }
1926           }
1927         } else {
1928           assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
1929         }
1930         if (n != sfpt) {
1931           extra_data_nodes.push(n);
1932           _igvn.register_new_node_with_optimizer(m);
1933           assert(get_ctrl(n) == cle_out, "what other control?");
1934           set_ctrl(m, new_cle_out);
1935           old_new.map(n->_idx, m);
1936         }
1937         stack.pop();
1938       }
1939     }
1940     if (mode == CloneIncludesStripMined) {
1941       _igvn.register_new_node_with_optimizer(new_sfpt);
1942       _igvn.register_new_node_with_optimizer(new_cle_out);
1943     }
1944     // Some other transformation may have pessimistically assign some
1945     // data nodes to the outer loop. Set their control so they are out
1946     // of the outer loop.
1947     ResourceMark rm;
1948     Unique_Node_List wq;
1949     for (uint i = 0; i < extra_data_nodes.size(); i++) {
1950       Node* old = extra_data_nodes.at(i);
1951       clone_outer_loop_helper(old, loop, outer_loop, old_new, wq, this, true);
1952     }
1953     Node* new_ctrl = cl->outer_loop_exit();
1954     assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
1955     for (uint i = 0; i < wq.size(); i++) {
1956       Node* n = wq.at(i);
1957       set_ctrl(n, new_ctrl);
1958       clone_outer_loop_helper(n, loop, outer_loop, old_new, wq, this, false);
1959     }
1960   } else {
1961     Node *newhead = old_new[loop->_head->_idx];
1962     set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1963   }
1964 }
1965 
1966 //------------------------------clone_loop-------------------------------------
1967 //
1968 //                   C L O N E   A   L O O P   B O D Y
1969 //
1970 // This is the basic building block of the loop optimizations.  It clones an
1971 // entire loop body.  It makes an old_new loop body mapping; with this mapping
1972 // you can find the new-loop equivalent to an old-loop node.  All new-loop
1973 // nodes are exactly equal to their old-loop counterparts, all edges are the
1974 // same.  All exits from the old-loop now have a RegionNode that merges the
1975 // equivalent new-loop path.  This is true even for the normal "loop-exit"
1976 // condition.  All uses of loop-invariant old-loop values now come from (one
1977 // or more) Phis that merge their new-loop equivalents.
1978 //
1979 // This operation leaves the graph in an illegal state: there are two valid
1980 // control edges coming from the loop pre-header to both loop bodies.  I'll
1981 // definitely have to hack the graph after running this transform.
1982 //
1983 // From this building block I will further edit edges to perform loop peeling
1984 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
1985 //
1986 // Parameter side_by_size_idom:
1987 //   When side_by_size_idom is NULL, the dominator tree is constructed for
1988 //      the clone loop to dominate the original.  Used in construction of
1989 //      pre-main-post loop sequence.
1990 //   When nonnull, the clone and original are side-by-side, both are
1991 //      dominated by the side_by_side_idom node.  Used in construction of
1992 //      unswitched loops.
1993 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
1994                                 CloneLoopMode mode, Node* side_by_side_idom) {
1995 
1996   LoopNode* head = loop->_head->as_Loop();
1997   head->verify_strip_mined(1);
1998 
1999   if (C->do_vector_loop() && PrintOpto) {
2000     const char* mname = C->method()->name()->as_quoted_ascii();
2001     if (mname != NULL) {
2002       tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2003     }
2004   }
2005 
2006   CloneMap& cm = C->clone_map();
2007   Dict* dict = cm.dict();
2008   if (C->do_vector_loop()) {
2009     cm.set_clone_idx(cm.max_gen()+1);
2010 #ifndef PRODUCT
2011     if (PrintOpto) {
2012       tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2013       loop->dump_head();
2014     }
2015 #endif
2016   }
2017 
2018   // Step 1: Clone the loop body.  Make the old->new mapping.
2019   uint i;
2020   for( i = 0; i < loop->_body.size(); i++ ) {
2021     Node *old = loop->_body.at(i);
2022     Node *nnn = old->clone();
2023     old_new.map( old->_idx, nnn );
2024     if (C->do_vector_loop()) {
2025       cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
2026     }
2027     _igvn.register_new_node_with_optimizer(nnn);
2028   }
2029 
2030   IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2031 
2032   // Step 2: Fix the edges in the new body.  If the old input is outside the
2033   // loop use it.  If the old input is INside the loop, use the corresponding
2034   // new node instead.
2035   for( i = 0; i < loop->_body.size(); i++ ) {
2036     Node *old = loop->_body.at(i);
2037     Node *nnn = old_new[old->_idx];
2038     // Fix CFG/Loop controlling the new node
2039     if (has_ctrl(old)) {
2040       set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2041     } else {
2042       set_loop(nnn, outer_loop->_parent);
2043       if (old->outcnt() > 0) {
2044         set_idom( nnn, old_new[idom(old)->_idx], dd );
2045       }
2046     }
2047     // Correct edges to the new node
2048     for( uint j = 0; j < nnn->req(); j++ ) {
2049         Node *n = nnn->in(j);
2050         if( n ) {
2051           IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
2052           if( loop->is_member( old_in_loop ) )
2053             nnn->set_req(j, old_new[n->_idx]);
2054         }
2055     }
2056     _igvn.hash_find_insert(nnn);
2057   }
2058 
2059   ResourceArea *area = Thread::current()->resource_area();
2060   Node_List extra_data_nodes(area); // data nodes in the outer strip mined loop
2061   clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2062 
2063   // Step 3: Now fix control uses.  Loop varying control uses have already
2064   // been fixed up (as part of all input edges in Step 2).  Loop invariant
2065   // control uses must be either an IfFalse or an IfTrue.  Make a merge
2066   // point to merge the old and new IfFalse/IfTrue nodes; make the use
2067   // refer to this.
2068   Node_List worklist(area);
2069   uint new_counter = C->unique();
2070   for( i = 0; i < loop->_body.size(); i++ ) {
2071     Node* old = loop->_body.at(i);
2072     if( !old->is_CFG() ) continue;
2073 
2074     // Copy uses to a worklist, so I can munge the def-use info
2075     // with impunity.
2076     for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2077       worklist.push(old->fast_out(j));
2078 
2079     while( worklist.size() ) {  // Visit all uses
2080       Node *use = worklist.pop();
2081       if (!has_node(use))  continue; // Ignore dead nodes
2082       IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2083       if( !loop->is_member( use_loop ) && use->is_CFG() ) {
2084         // Both OLD and USE are CFG nodes here.
2085         assert( use->is_Proj(), "" );
2086         Node* nnn = old_new[old->_idx];
2087 
2088         Node* newuse = NULL;
2089         if (head->is_strip_mined() && mode != IgnoreStripMined) {
2090           CountedLoopNode* cl = head->as_CountedLoop();
2091           CountedLoopEndNode* cle = cl->loopexit();
2092           Node* cle_out = cle->proj_out_or_null(false);
2093           if (use == cle_out) {
2094             IfNode* le = cl->outer_loop_end();
2095             use = le->proj_out(false);
2096             use_loop = get_loop(use);
2097             if (mode == CloneIncludesStripMined) {
2098               nnn = old_new[le->_idx];
2099             } else {
2100               newuse = old_new[cle_out->_idx];
2101             }
2102           }
2103         }
2104         if (newuse == NULL) {
2105           newuse = use->clone();
2106         }
2107 
2108         // Clone the loop exit control projection
2109         if (C->do_vector_loop()) {
2110           cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
2111         }
2112         newuse->set_req(0,nnn);
2113         _igvn.register_new_node_with_optimizer(newuse);
2114         set_loop(newuse, use_loop);
2115         set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2116 
2117         // We need a Region to merge the exit from the peeled body and the
2118         // exit from the old loop body.
2119         RegionNode *r = new RegionNode(3);
2120         // Map the old use to the new merge point
2121         old_new.map( use->_idx, r );
2122         uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
2123         assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
2124 
2125         // The original user of 'use' uses 'r' instead.
2126         for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2127           Node* useuse = use->last_out(l);
2128           _igvn.rehash_node_delayed(useuse);
2129           uint uses_found = 0;
2130           if( useuse->in(0) == use ) {
2131             useuse->set_req(0, r);
2132             uses_found++;
2133             if( useuse->is_CFG() ) {
2134               assert( dom_depth(useuse) > dd_r, "" );
2135               set_idom(useuse, r, dom_depth(useuse));
2136             }
2137           }
2138           for( uint k = 1; k < useuse->req(); k++ ) {
2139             if( useuse->in(k) == use ) {
2140               useuse->set_req(k, r);
2141               uses_found++;
2142               if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2143                 assert(dom_depth(useuse) > dd_r , "");
2144                 set_idom(useuse, r, dom_depth(useuse));
2145               }
2146             }
2147           }
2148           l -= uses_found;    // we deleted 1 or more copies of this edge
2149         }
2150 
2151         // Now finish up 'r'
2152         r->set_req( 1, newuse );
2153         r->set_req( 2,    use );
2154         _igvn.register_new_node_with_optimizer(r);
2155         set_loop(r, use_loop);
2156         set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
2157       } // End of if a loop-exit test
2158     }
2159   }
2160 
2161   // Step 4: If loop-invariant use is not control, it must be dominated by a
2162   // loop exit IfFalse/IfTrue.  Find "proper" loop exit.  Make a Region
2163   // there if needed.  Make a Phi there merging old and new used values.
2164   Node_List *split_if_set = NULL;
2165   Node_List *split_bool_set = NULL;
2166   Node_List *split_cex_set = NULL;
2167   for( i = 0; i < loop->_body.size(); i++ ) {
2168     Node* old = loop->_body.at(i);
2169     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2170                                 split_bool_set, split_cex_set, worklist, new_counter,
2171                                 mode);
2172   }
2173 
2174   for (i = 0; i < extra_data_nodes.size(); i++) {
2175     Node* old = extra_data_nodes.at(i);
2176     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2177                                 split_bool_set, split_cex_set, worklist, new_counter,
2178                                 mode);
2179   }
2180 
2181   // Check for IFs that need splitting/cloning.  Happens if an IF outside of
2182   // the loop uses a condition set in the loop.  The original IF probably
2183   // takes control from one or more OLD Regions (which in turn get from NEW
2184   // Regions).  In any case, there will be a set of Phis for each merge point
2185   // from the IF up to where the original BOOL def exists the loop.
2186   if (split_if_set) {
2187     while (split_if_set->size()) {
2188       Node *iff = split_if_set->pop();
2189       if (iff->in(1)->is_Phi()) {
2190         Node *b = clone_iff(iff->in(1)->as_Phi(), loop);
2191         _igvn.replace_input_of(iff, 1, b);
2192       }
2193     }
2194   }
2195   if (split_bool_set) {
2196     while (split_bool_set->size()) {
2197       Node *b = split_bool_set->pop();
2198       Node *phi = b->in(1);
2199       assert(phi->is_Phi(), "");
2200       CmpNode *cmp = clone_bool((PhiNode*)phi, loop);
2201       _igvn.replace_input_of(b, 1, cmp);
2202     }
2203   }
2204   if (split_cex_set) {
2205     while (split_cex_set->size()) {
2206       Node *b = split_cex_set->pop();
2207       assert(b->in(0)->is_Region(), "");
2208       assert(b->in(1)->is_Phi(), "");
2209       assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2210       split_up(b, b->in(0), NULL);
2211     }
2212   }
2213 
2214 }
2215 
2216 
2217 //---------------------- stride_of_possible_iv -------------------------------------
2218 // Looks for an iff/bool/comp with one operand of the compare
2219 // being a cycle involving an add and a phi,
2220 // with an optional truncation (left-shift followed by a right-shift)
2221 // of the add. Returns zero if not an iv.
2222 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2223   Node* trunc1 = NULL;
2224   Node* trunc2 = NULL;
2225   const TypeInt* ttype = NULL;
2226   if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
2227     return 0;
2228   }
2229   BoolNode* bl = iff->in(1)->as_Bool();
2230   Node* cmp = bl->in(1);
2231   if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2232     return 0;
2233   }
2234   // Must have an invariant operand
2235   if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2236     return 0;
2237   }
2238   Node* add2 = NULL;
2239   Node* cmp1 = cmp->in(1);
2240   if (cmp1->is_Phi()) {
2241     // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2242     Node* phi = cmp1;
2243     for (uint i = 1; i < phi->req(); i++) {
2244       Node* in = phi->in(i);
2245       Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2246                                 &trunc1, &trunc2, &ttype);
2247       if (add && add->in(1) == phi) {
2248         add2 = add->in(2);
2249         break;
2250       }
2251     }
2252   } else {
2253     // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2254     Node* addtrunc = cmp1;
2255     Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2256                                 &trunc1, &trunc2, &ttype);
2257     if (add && add->in(1)->is_Phi()) {
2258       Node* phi = add->in(1);
2259       for (uint i = 1; i < phi->req(); i++) {
2260         if (phi->in(i) == addtrunc) {
2261           add2 = add->in(2);
2262           break;
2263         }
2264       }
2265     }
2266   }
2267   if (add2 != NULL) {
2268     const TypeInt* add2t = _igvn.type(add2)->is_int();
2269     if (add2t->is_con()) {
2270       return add2t->get_con();
2271     }
2272   }
2273   return 0;
2274 }
2275 
2276 
2277 //---------------------- stay_in_loop -------------------------------------
2278 // Return the (unique) control output node that's in the loop (if it exists.)
2279 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2280   Node* unique = NULL;
2281   if (!n) return NULL;
2282   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2283     Node* use = n->fast_out(i);
2284     if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2285       if (unique != NULL) {
2286         return NULL;
2287       }
2288       unique = use;
2289     }
2290   }
2291   return unique;
2292 }
2293 
2294 //------------------------------ register_node -------------------------------------
2295 // Utility to register node "n" with PhaseIdealLoop
2296 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
2297   _igvn.register_new_node_with_optimizer(n);
2298   loop->_body.push(n);
2299   if (n->is_CFG()) {
2300     set_loop(n, loop);
2301     set_idom(n, pred, ddepth);
2302   } else {
2303     set_ctrl(n, pred);
2304   }
2305 }
2306 
2307 //------------------------------ proj_clone -------------------------------------
2308 // Utility to create an if-projection
2309 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2310   ProjNode* c = p->clone()->as_Proj();
2311   c->set_req(0, iff);
2312   return c;
2313 }
2314 
2315 //------------------------------ short_circuit_if -------------------------------------
2316 // Force the iff control output to be the live_proj
2317 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2318   guarantee(live_proj != NULL, "null projection");
2319   int proj_con = live_proj->_con;
2320   assert(proj_con == 0 || proj_con == 1, "false or true projection");
2321   Node *con = _igvn.intcon(proj_con);
2322   set_ctrl(con, C->root());
2323   if (iff) {
2324     iff->set_req(1, con);
2325   }
2326   return con;
2327 }
2328 
2329 //------------------------------ insert_if_before_proj -------------------------------------
2330 // Insert a new if before an if projection (* - new node)
2331 //
2332 // before
2333 //           if(test)
2334 //           /     \
2335 //          v       v
2336 //    other-proj   proj (arg)
2337 //
2338 // after
2339 //           if(test)
2340 //           /     \
2341 //          /       v
2342 //         |      * proj-clone
2343 //         v          |
2344 //    other-proj      v
2345 //                * new_if(relop(cmp[IU](left,right)))
2346 //                  /  \
2347 //                 v    v
2348 //         * new-proj  proj
2349 //         (returned)
2350 //
2351 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2352   IfNode* iff = proj->in(0)->as_If();
2353   IdealLoopTree *loop = get_loop(proj);
2354   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2355   int ddepth = dom_depth(proj);
2356 
2357   _igvn.rehash_node_delayed(iff);
2358   _igvn.rehash_node_delayed(proj);
2359 
2360   proj->set_req(0, NULL);  // temporary disconnect
2361   ProjNode* proj2 = proj_clone(proj, iff);
2362   register_node(proj2, loop, iff, ddepth);
2363 
2364   Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2365   register_node(cmp, loop, proj2, ddepth);
2366 
2367   BoolNode* bol = new BoolNode(cmp, relop);
2368   register_node(bol, loop, proj2, ddepth);
2369 
2370   int opcode = iff->Opcode();
2371   assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2372   IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2373     new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2374   register_node(new_if, loop, proj2, ddepth);
2375 
2376   proj->set_req(0, new_if); // reattach
2377   set_idom(proj, new_if, ddepth);
2378 
2379   ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2380   guarantee(new_exit != NULL, "null exit node");
2381   register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2382 
2383   return new_exit;
2384 }
2385 
2386 //------------------------------ insert_region_before_proj -------------------------------------
2387 // Insert a region before an if projection (* - new node)
2388 //
2389 // before
2390 //           if(test)
2391 //          /      |
2392 //         v       |
2393 //       proj      v
2394 //               other-proj
2395 //
2396 // after
2397 //           if(test)
2398 //          /      |
2399 //         v       |
2400 // * proj-clone    v
2401 //         |     other-proj
2402 //         v
2403 // * new-region
2404 //         |
2405 //         v
2406 // *      dum_if
2407 //       /     \
2408 //      v       \
2409 // * dum-proj    v
2410 //              proj
2411 //
2412 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2413   IfNode* iff = proj->in(0)->as_If();
2414   IdealLoopTree *loop = get_loop(proj);
2415   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2416   int ddepth = dom_depth(proj);
2417 
2418   _igvn.rehash_node_delayed(iff);
2419   _igvn.rehash_node_delayed(proj);
2420 
2421   proj->set_req(0, NULL);  // temporary disconnect
2422   ProjNode* proj2 = proj_clone(proj, iff);
2423   register_node(proj2, loop, iff, ddepth);
2424 
2425   RegionNode* reg = new RegionNode(2);
2426   reg->set_req(1, proj2);
2427   register_node(reg, loop, iff, ddepth);
2428 
2429   IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2430   register_node(dum_if, loop, reg, ddepth);
2431 
2432   proj->set_req(0, dum_if); // reattach
2433   set_idom(proj, dum_if, ddepth);
2434 
2435   ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2436   register_node(dum_proj, loop, dum_if, ddepth);
2437 
2438   return reg;
2439 }
2440 
2441 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2442 // Clone a signed compare loop exit from an unsigned compare and
2443 // insert it before the unsigned cmp on the stay-in-loop path.
2444 // All new nodes inserted in the dominator tree between the original
2445 // if and it's projections.  The original if test is replaced with
2446 // a constant to force the stay-in-loop path.
2447 //
2448 // This is done to make sure that the original if and it's projections
2449 // still dominate the same set of control nodes, that the ctrl() relation
2450 // from data nodes to them is preserved, and that their loop nesting is
2451 // preserved.
2452 //
2453 // before
2454 //          if(i <u limit)    unsigned compare loop exit
2455 //         /       |
2456 //        v        v
2457 //   exit-proj   stay-in-loop-proj
2458 //
2459 // after
2460 //          if(stay-in-loop-const)  original if
2461 //         /       |
2462 //        /        v
2463 //       /  if(i <  limit)    new signed test
2464 //      /  /       |
2465 //     /  /        v
2466 //    /  /  if(i <u limit)    new cloned unsigned test
2467 //   /  /   /      |
2468 //   v  v  v       |
2469 //    region       |
2470 //        |        |
2471 //      dum-if     |
2472 //     /  |        |
2473 // ether  |        |
2474 //        v        v
2475 //   exit-proj   stay-in-loop-proj
2476 //
2477 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2478   const bool Signed   = true;
2479   const bool Unsigned = false;
2480 
2481   BoolNode* bol = if_cmpu->in(1)->as_Bool();
2482   if (bol->_test._test != BoolTest::lt) return NULL;
2483   CmpNode* cmpu = bol->in(1)->as_Cmp();
2484   if (cmpu->Opcode() != Op_CmpU) return NULL;
2485   int stride = stride_of_possible_iv(if_cmpu);
2486   if (stride == 0) return NULL;
2487 
2488   Node* lp_proj = stay_in_loop(if_cmpu, loop);
2489   guarantee(lp_proj != NULL, "null loop node");
2490 
2491   ProjNode* lp_continue = lp_proj->as_Proj();
2492   ProjNode* lp_exit     = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2493 
2494   Node* limit = NULL;
2495   if (stride > 0) {
2496     limit = cmpu->in(2);
2497   } else {
2498     limit = _igvn.makecon(TypeInt::ZERO);
2499     set_ctrl(limit, C->root());
2500   }
2501   // Create a new region on the exit path
2502   RegionNode* reg = insert_region_before_proj(lp_exit);
2503   guarantee(reg != NULL, "null region node");
2504 
2505   // Clone the if-cmpu-true-false using a signed compare
2506   BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2507   ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2508   reg->add_req(cmpi_exit);
2509 
2510   // Clone the if-cmpu-true-false
2511   BoolTest::mask rel_u = bol->_test._test;
2512   ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2513   reg->add_req(cmpu_exit);
2514 
2515   // Force original if to stay in loop.
2516   short_circuit_if(if_cmpu, lp_continue);
2517 
2518   return cmpi_exit->in(0)->as_If();
2519 }
2520 
2521 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2522 // Remove a previously inserted signed compare loop exit.
2523 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2524   Node* lp_proj = stay_in_loop(if_cmp, loop);
2525   assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2526          stay_in_loop(lp_proj, loop)->is_If() &&
2527          stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2528   Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2529   set_ctrl(con, C->root());
2530   if_cmp->set_req(1, con);
2531 }
2532 
2533 //------------------------------ scheduled_nodelist -------------------------------------
2534 // Create a post order schedule of nodes that are in the
2535 // "member" set.  The list is returned in "sched".
2536 // The first node in "sched" is the loop head, followed by
2537 // nodes which have no inputs in the "member" set, and then
2538 // followed by the nodes that have an immediate input dependence
2539 // on a node in "sched".
2540 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2541 
2542   assert(member.test(loop->_head->_idx), "loop head must be in member set");
2543   Arena *a = Thread::current()->resource_area();
2544   VectorSet visited(a);
2545   Node_Stack nstack(a, loop->_body.size());
2546 
2547   Node* n  = loop->_head;  // top of stack is cached in "n"
2548   uint idx = 0;
2549   visited.set(n->_idx);
2550 
2551   // Initially push all with no inputs from within member set
2552   for(uint i = 0; i < loop->_body.size(); i++ ) {
2553     Node *elt = loop->_body.at(i);
2554     if (member.test(elt->_idx)) {
2555       bool found = false;
2556       for (uint j = 0; j < elt->req(); j++) {
2557         Node* def = elt->in(j);
2558         if (def && member.test(def->_idx) && def != elt) {
2559           found = true;
2560           break;
2561         }
2562       }
2563       if (!found && elt != loop->_head) {
2564         nstack.push(n, idx);
2565         n = elt;
2566         assert(!visited.test(n->_idx), "not seen yet");
2567         visited.set(n->_idx);
2568       }
2569     }
2570   }
2571 
2572   // traverse out's that are in the member set
2573   while (true) {
2574     if (idx < n->outcnt()) {
2575       Node* use = n->raw_out(idx);
2576       idx++;
2577       if (!visited.test_set(use->_idx)) {
2578         if (member.test(use->_idx)) {
2579           nstack.push(n, idx);
2580           n = use;
2581           idx = 0;
2582         }
2583       }
2584     } else {
2585       // All outputs processed
2586       sched.push(n);
2587       if (nstack.is_empty()) break;
2588       n   = nstack.node();
2589       idx = nstack.index();
2590       nstack.pop();
2591     }
2592   }
2593 }
2594 
2595 
2596 //------------------------------ has_use_in_set -------------------------------------
2597 // Has a use in the vector set
2598 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2599   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2600     Node* use = n->fast_out(j);
2601     if (vset.test(use->_idx)) {
2602       return true;
2603     }
2604   }
2605   return false;
2606 }
2607 
2608 
2609 //------------------------------ has_use_internal_to_set -------------------------------------
2610 // Has use internal to the vector set (ie. not in a phi at the loop head)
2611 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2612   Node* head  = loop->_head;
2613   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2614     Node* use = n->fast_out(j);
2615     if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2616       return true;
2617     }
2618   }
2619   return false;
2620 }
2621 
2622 
2623 //------------------------------ clone_for_use_outside_loop -------------------------------------
2624 // clone "n" for uses that are outside of loop
2625 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2626   int cloned = 0;
2627   assert(worklist.size() == 0, "should be empty");
2628   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2629     Node* use = n->fast_out(j);
2630     if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2631       worklist.push(use);
2632     }
2633   }
2634   while( worklist.size() ) {
2635     Node *use = worklist.pop();
2636     if (!has_node(use) || use->in(0) == C->top()) continue;
2637     uint j;
2638     for (j = 0; j < use->req(); j++) {
2639       if (use->in(j) == n) break;
2640     }
2641     assert(j < use->req(), "must be there");
2642 
2643     // clone "n" and insert it between the inputs of "n" and the use outside the loop
2644     Node* n_clone = n->clone();
2645     _igvn.replace_input_of(use, j, n_clone);
2646     cloned++;
2647     Node* use_c;
2648     if (!use->is_Phi()) {
2649       use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2650     } else {
2651       // Use in a phi is considered a use in the associated predecessor block
2652       use_c = use->in(0)->in(j);
2653     }
2654     set_ctrl(n_clone, use_c);
2655     assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2656     get_loop(use_c)->_body.push(n_clone);
2657     _igvn.register_new_node_with_optimizer(n_clone);
2658 #ifndef PRODUCT
2659     if (TracePartialPeeling) {
2660       tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2661     }
2662 #endif
2663   }
2664   return cloned;
2665 }
2666 
2667 
2668 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2669 // clone "n" for special uses that are in the not_peeled region.
2670 // If these def-uses occur in separate blocks, the code generator
2671 // marks the method as not compilable.  For example, if a "BoolNode"
2672 // is in a different basic block than the "IfNode" that uses it, then
2673 // the compilation is aborted in the code generator.
2674 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2675                                                         VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2676   if (n->is_Phi() || n->is_Load()) {
2677     return;
2678   }
2679   assert(worklist.size() == 0, "should be empty");
2680   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2681     Node* use = n->fast_out(j);
2682     if ( not_peel.test(use->_idx) &&
2683          (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2684          use->in(1) == n)  {
2685       worklist.push(use);
2686     }
2687   }
2688   if (worklist.size() > 0) {
2689     // clone "n" and insert it between inputs of "n" and the use
2690     Node* n_clone = n->clone();
2691     loop->_body.push(n_clone);
2692     _igvn.register_new_node_with_optimizer(n_clone);
2693     set_ctrl(n_clone, get_ctrl(n));
2694     sink_list.push(n_clone);
2695     not_peel <<= n_clone->_idx;  // add n_clone to not_peel set.
2696 #ifndef PRODUCT
2697     if (TracePartialPeeling) {
2698       tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2699     }
2700 #endif
2701     while( worklist.size() ) {
2702       Node *use = worklist.pop();
2703       _igvn.rehash_node_delayed(use);
2704       for (uint j = 1; j < use->req(); j++) {
2705         if (use->in(j) == n) {
2706           use->set_req(j, n_clone);
2707         }
2708       }
2709     }
2710   }
2711 }
2712 
2713 
2714 //------------------------------ insert_phi_for_loop -------------------------------------
2715 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2716 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2717   Node *phi = PhiNode::make(lp, back_edge_val);
2718   phi->set_req(LoopNode::EntryControl, lp_entry_val);
2719   // Use existing phi if it already exists
2720   Node *hit = _igvn.hash_find_insert(phi);
2721   if( hit == NULL ) {
2722     _igvn.register_new_node_with_optimizer(phi);
2723     set_ctrl(phi, lp);
2724   } else {
2725     // Remove the new phi from the graph and use the hit
2726     _igvn.remove_dead_node(phi);
2727     phi = hit;
2728   }
2729   _igvn.replace_input_of(use, idx, phi);
2730 }
2731 
2732 #ifdef ASSERT
2733 //------------------------------ is_valid_loop_partition -------------------------------------
2734 // Validate the loop partition sets: peel and not_peel
2735 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2736                                               VectorSet& not_peel ) {
2737   uint i;
2738   // Check that peel_list entries are in the peel set
2739   for (i = 0; i < peel_list.size(); i++) {
2740     if (!peel.test(peel_list.at(i)->_idx)) {
2741       return false;
2742     }
2743   }
2744   // Check at loop members are in one of peel set or not_peel set
2745   for (i = 0; i < loop->_body.size(); i++ ) {
2746     Node *def  = loop->_body.at(i);
2747     uint di = def->_idx;
2748     // Check that peel set elements are in peel_list
2749     if (peel.test(di)) {
2750       if (not_peel.test(di)) {
2751         return false;
2752       }
2753       // Must be in peel_list also
2754       bool found = false;
2755       for (uint j = 0; j < peel_list.size(); j++) {
2756         if (peel_list.at(j)->_idx == di) {
2757           found = true;
2758           break;
2759         }
2760       }
2761       if (!found) {
2762         return false;
2763       }
2764     } else if (not_peel.test(di)) {
2765       if (peel.test(di)) {
2766         return false;
2767       }
2768     } else {
2769       return false;
2770     }
2771   }
2772   return true;
2773 }
2774 
2775 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2776 // Ensure a use outside of loop is of the right form
2777 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2778   Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2779   return (use->is_Phi() &&
2780           use_c->is_Region() && use_c->req() == 3 &&
2781           (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2782            use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2783            use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2784           loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2785 }
2786 
2787 //------------------------------ is_valid_clone_loop_form -------------------------------------
2788 // Ensure that all uses outside of loop are of the right form
2789 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2790                                                uint orig_exit_idx, uint clone_exit_idx) {
2791   uint len = peel_list.size();
2792   for (uint i = 0; i < len; i++) {
2793     Node *def = peel_list.at(i);
2794 
2795     for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2796       Node *use = def->fast_out(j);
2797       Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2798       if (!loop->is_member(get_loop(use_c))) {
2799         // use is not in the loop, check for correct structure
2800         if (use->in(0) == def) {
2801           // Okay
2802         } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2803           return false;
2804         }
2805       }
2806     }
2807   }
2808   return true;
2809 }
2810 #endif
2811 
2812 //------------------------------ partial_peel -------------------------------------
2813 // Partially peel (aka loop rotation) the top portion of a loop (called
2814 // the peel section below) by cloning it and placing one copy just before
2815 // the new loop head and the other copy at the bottom of the new loop.
2816 //
2817 //    before                       after                where it came from
2818 //
2819 //    stmt1                        stmt1
2820 //  loop:                          stmt2                     clone
2821 //    stmt2                        if condA goto exitA       clone
2822 //    if condA goto exitA        new_loop:                   new
2823 //    stmt3                        stmt3                     clone
2824 //    if !condB goto loop          if condB goto exitB       clone
2825 //  exitB:                         stmt2                     orig
2826 //    stmt4                        if !condA goto new_loop   orig
2827 //  exitA:                         goto exitA
2828 //                               exitB:
2829 //                                 stmt4
2830 //                               exitA:
2831 //
2832 // Step 1: find the cut point: an exit test on probable
2833 //         induction variable.
2834 // Step 2: schedule (with cloning) operations in the peel
2835 //         section that can be executed after the cut into
2836 //         the section that is not peeled.  This may need
2837 //         to clone operations into exit blocks.  For
2838 //         instance, a reference to A[i] in the not-peel
2839 //         section and a reference to B[i] in an exit block
2840 //         may cause a left-shift of i by 2 to be placed
2841 //         in the peel block.  This step will clone the left
2842 //         shift into the exit block and sink the left shift
2843 //         from the peel to the not-peel section.
2844 // Step 3: clone the loop, retarget the control, and insert
2845 //         phis for values that are live across the new loop
2846 //         head.  This is very dependent on the graph structure
2847 //         from clone_loop.  It creates region nodes for
2848 //         exit control and associated phi nodes for values
2849 //         flow out of the loop through that exit.  The region
2850 //         node is dominated by the clone's control projection.
2851 //         So the clone's peel section is placed before the
2852 //         new loop head, and the clone's not-peel section is
2853 //         forms the top part of the new loop.  The original
2854 //         peel section forms the tail of the new loop.
2855 // Step 4: update the dominator tree and recompute the
2856 //         dominator depth.
2857 //
2858 //                   orig
2859 //
2860 //                   stmt1
2861 //                     |
2862 //                     v
2863 //               loop predicate
2864 //                     |
2865 //                     v
2866 //                   loop<----+
2867 //                     |      |
2868 //                   stmt2    |
2869 //                     |      |
2870 //                     v      |
2871 //                    ifA     |
2872 //                   / |      |
2873 //                  v  v      |
2874 //               false true   ^  <-- last_peel
2875 //               /     |      |
2876 //              /   ===|==cut |
2877 //             /     stmt3    |  <-- first_not_peel
2878 //            /        |      |
2879 //            |        v      |
2880 //            v       ifB     |
2881 //          exitA:   / \      |
2882 //                  /   \     |
2883 //                 v     v    |
2884 //               false true   |
2885 //               /       \    |
2886 //              /         ----+
2887 //             |
2888 //             v
2889 //           exitB:
2890 //           stmt4
2891 //
2892 //
2893 //            after clone loop
2894 //
2895 //                   stmt1
2896 //                     |
2897 //                     v
2898 //               loop predicate
2899 //                 /       \
2900 //        clone   /         \   orig
2901 //               /           \
2902 //              /             \
2903 //             v               v
2904 //   +---->loop                loop<----+
2905 //   |      |                    |      |
2906 //   |    stmt2                stmt2    |
2907 //   |      |                    |      |
2908 //   |      v                    v      |
2909 //   |      ifA                 ifA     |
2910 //   |      | \                / |      |
2911 //   |      v  v              v  v      |
2912 //   ^    true  false      false true   ^  <-- last_peel
2913 //   |      |   ^   \       /    |      |
2914 //   | cut==|==  \   \     /  ===|==cut |
2915 //   |    stmt3   \   \   /    stmt3    |  <-- first_not_peel
2916 //   |      |    dom   | |       |      |
2917 //   |      v      \  1v v2      v      |
2918 //   |      ifB     regionA     ifB     |
2919 //   |      / \        |       / \      |
2920 //   |     /   \       v      /   \     |
2921 //   |    v     v    exitA:  v     v    |
2922 //   |    true  false      false true   |
2923 //   |    /     ^   \      /       \    |
2924 //   +----       \   \    /         ----+
2925 //               dom  \  /
2926 //                 \  1v v2
2927 //                  regionB
2928 //                     |
2929 //                     v
2930 //                   exitB:
2931 //                   stmt4
2932 //
2933 //
2934 //           after partial peel
2935 //
2936 //                  stmt1
2937 //                     |
2938 //                     v
2939 //               loop predicate
2940 //                 /
2941 //        clone   /             orig
2942 //               /          TOP
2943 //              /             \
2944 //             v               v
2945 //    TOP->loop                loop----+
2946 //          |                    |      |
2947 //        stmt2                stmt2    |
2948 //          |                    |      |
2949 //          v                    v      |
2950 //          ifA                 ifA     |
2951 //          | \                / |      |
2952 //          v  v              v  v      |
2953 //        true  false      false true   |     <-- last_peel
2954 //          |   ^   \       /    +------|---+
2955 //  +->newloop   \   \     /  === ==cut |   |
2956 //  |     stmt3   \   \   /     TOP     |   |
2957 //  |       |    dom   | |      stmt3   |   | <-- first_not_peel
2958 //  |       v      \  1v v2      v      |   |
2959 //  |       ifB     regionA     ifB     ^   v
2960 //  |       / \        |       / \      |   |
2961 //  |      /   \       v      /   \     |   |
2962 //  |     v     v    exitA:  v     v    |   |
2963 //  |     true  false      false true   |   |
2964 //  |     /     ^   \      /       \    |   |
2965 //  |    |       \   \    /         v   |   |
2966 //  |    |       dom  \  /         TOP  |   |
2967 //  |    |         \  1v v2             |   |
2968 //  ^    v          regionB             |   |
2969 //  |    |             |                |   |
2970 //  |    |             v                ^   v
2971 //  |    |           exitB:             |   |
2972 //  |    |           stmt4              |   |
2973 //  |    +------------>-----------------+   |
2974 //  |                                       |
2975 //  +-----------------<---------------------+
2976 //
2977 //
2978 //              final graph
2979 //
2980 //                  stmt1
2981 //                    |
2982 //                    v
2983 //               loop predicate
2984 //                    |
2985 //                    v
2986 //                  stmt2 clone
2987 //                    |
2988 //                    v
2989 //         ........> ifA clone
2990 //         :        / |
2991 //        dom      /  |
2992 //         :      v   v
2993 //         :  false   true
2994 //         :  |       |
2995 //         :  |       v
2996 //         :  |    newloop<-----+
2997 //         :  |        |        |
2998 //         :  |     stmt3 clone |
2999 //         :  |        |        |
3000 //         :  |        v        |
3001 //         :  |       ifB       |
3002 //         :  |      / \        |
3003 //         :  |     v   v       |
3004 //         :  |  false true     |
3005 //         :  |   |     |       |
3006 //         :  |   v    stmt2    |
3007 //         :  | exitB:  |       |
3008 //         :  | stmt4   v       |
3009 //         :  |       ifA orig  |
3010 //         :  |      /  \       |
3011 //         :  |     /    \      |
3012 //         :  |    v     v      |
3013 //         :  |  false  true    |
3014 //         :  |  /        \     |
3015 //         :  v  v         -----+
3016 //          RegionA
3017 //             |
3018 //             v
3019 //           exitA
3020 //
3021 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3022 
3023   assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3024   if (!loop->_head->is_Loop()) {
3025     return false;
3026   }
3027   LoopNode *head = loop->_head->as_Loop();
3028 
3029   if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3030     return false;
3031   }
3032 
3033   // Check for complex exit control
3034   for (uint ii = 0; ii < loop->_body.size(); ii++) {
3035     Node *n = loop->_body.at(ii);
3036     int opc = n->Opcode();
3037     if (n->is_Call()        ||
3038         opc == Op_Catch     ||
3039         opc == Op_CatchProj ||
3040         opc == Op_Jump      ||
3041         opc == Op_JumpProj) {
3042 #ifndef PRODUCT
3043       if (TracePartialPeeling) {
3044         tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3045       }
3046 #endif
3047       return false;
3048     }
3049   }
3050 
3051   int dd = dom_depth(head);
3052 
3053   // Step 1: find cut point
3054 
3055   // Walk up dominators to loop head looking for first loop exit
3056   // which is executed on every path thru loop.
3057   IfNode *peel_if = NULL;
3058   IfNode *peel_if_cmpu = NULL;
3059 
3060   Node *iff = loop->tail();
3061   while (iff != head) {
3062     if (iff->is_If()) {
3063       Node *ctrl = get_ctrl(iff->in(1));
3064       if (ctrl->is_top()) return false; // Dead test on live IF.
3065       // If loop-varying exit-test, check for induction variable
3066       if (loop->is_member(get_loop(ctrl)) &&
3067           loop->is_loop_exit(iff) &&
3068           is_possible_iv_test(iff)) {
3069         Node* cmp = iff->in(1)->in(1);
3070         if (cmp->Opcode() == Op_CmpI) {
3071           peel_if = iff->as_If();
3072         } else {
3073           assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3074           peel_if_cmpu = iff->as_If();
3075         }
3076       }
3077     }
3078     iff = idom(iff);
3079   }
3080 
3081   // Prefer signed compare over unsigned compare.
3082   IfNode* new_peel_if = NULL;
3083   if (peel_if == NULL) {
3084     if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
3085       return false;   // No peel point found
3086     }
3087     new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3088     if (new_peel_if == NULL) {
3089       return false;   // No peel point found
3090     }
3091     peel_if = new_peel_if;
3092   }
3093   Node* last_peel        = stay_in_loop(peel_if, loop);
3094   Node* first_not_peeled = stay_in_loop(last_peel, loop);
3095   if (first_not_peeled == NULL || first_not_peeled == head) {
3096     return false;
3097   }
3098 
3099 #ifndef PRODUCT
3100   if (TraceLoopOpts) {
3101     tty->print("PartialPeel  ");
3102     loop->dump_head();
3103   }
3104 
3105   if (TracePartialPeeling) {
3106     tty->print_cr("before partial peel one iteration");
3107     Node_List wl;
3108     Node* t = head->in(2);
3109     while (true) {
3110       wl.push(t);
3111       if (t == head) break;
3112       t = idom(t);
3113     }
3114     while (wl.size() > 0) {
3115       Node* tt = wl.pop();
3116       tt->dump();
3117       if (tt == last_peel) tty->print_cr("-- cut --");
3118     }
3119   }
3120 #endif
3121   ResourceArea *area = Thread::current()->resource_area();
3122   VectorSet peel(area);
3123   VectorSet not_peel(area);
3124   Node_List peel_list(area);
3125   Node_List worklist(area);
3126   Node_List sink_list(area);
3127 
3128   if (!may_require_nodes(loop->est_loop_clone_sz(2))) {
3129     return false;
3130   }
3131 
3132   // Set of cfg nodes to peel are those that are executable from
3133   // the head through last_peel.
3134   assert(worklist.size() == 0, "should be empty");
3135   worklist.push(head);
3136   peel.set(head->_idx);
3137   while (worklist.size() > 0) {
3138     Node *n = worklist.pop();
3139     if (n != last_peel) {
3140       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3141         Node* use = n->fast_out(j);
3142         if (use->is_CFG() &&
3143             loop->is_member(get_loop(use)) &&
3144             !peel.test_set(use->_idx)) {
3145           worklist.push(use);
3146         }
3147       }
3148     }
3149   }
3150 
3151   // Set of non-cfg nodes to peel are those that are control
3152   // dependent on the cfg nodes.
3153   uint i;
3154   for(i = 0; i < loop->_body.size(); i++ ) {
3155     Node *n = loop->_body.at(i);
3156     Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3157     if (peel.test(n_c->_idx)) {
3158       peel.set(n->_idx);
3159     } else {
3160       not_peel.set(n->_idx);
3161     }
3162   }
3163 
3164   // Step 2: move operations from the peeled section down into the
3165   //         not-peeled section
3166 
3167   // Get a post order schedule of nodes in the peel region
3168   // Result in right-most operand.
3169   scheduled_nodelist(loop, peel, peel_list );
3170 
3171   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3172 
3173   // For future check for too many new phis
3174   uint old_phi_cnt = 0;
3175   for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3176     Node* use = head->fast_out(j);
3177     if (use->is_Phi()) old_phi_cnt++;
3178   }
3179 
3180 #ifndef PRODUCT
3181   if (TracePartialPeeling) {
3182     tty->print_cr("\npeeled list");
3183   }
3184 #endif
3185 
3186   // Evacuate nodes in peel region into the not_peeled region if possible
3187   uint new_phi_cnt = 0;
3188   uint cloned_for_outside_use = 0;
3189   for (i = 0; i < peel_list.size();) {
3190     Node* n = peel_list.at(i);
3191 #ifndef PRODUCT
3192   if (TracePartialPeeling) n->dump();
3193 #endif
3194     bool incr = true;
3195     if ( !n->is_CFG() ) {
3196 
3197       if ( has_use_in_set(n, not_peel) ) {
3198 
3199         // If not used internal to the peeled region,
3200         // move "n" from peeled to not_peeled region.
3201 
3202         if ( !has_use_internal_to_set(n, peel, loop) ) {
3203 
3204           // if not pinned and not a load (which maybe anti-dependent on a store)
3205           // and not a CMove (Matcher expects only bool->cmove).
3206           if (n->in(0) == NULL && !n->is_Load() && !n->is_CMove()) {
3207             cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
3208             sink_list.push(n);
3209             peel     >>= n->_idx; // delete n from peel set.
3210             not_peel <<= n->_idx; // add n to not_peel set.
3211             peel_list.remove(i);
3212             incr = false;
3213 #ifndef PRODUCT
3214             if (TracePartialPeeling) {
3215               tty->print_cr("sink to not_peeled region: %d newbb: %d",
3216                             n->_idx, get_ctrl(n)->_idx);
3217             }
3218 #endif
3219           }
3220         } else {
3221           // Otherwise check for special def-use cases that span
3222           // the peel/not_peel boundary such as bool->if
3223           clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
3224           new_phi_cnt++;
3225         }
3226       }
3227     }
3228     if (incr) i++;
3229   }
3230 
3231   if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
3232 #ifndef PRODUCT
3233     if (TracePartialPeeling) {
3234       tty->print_cr("\nToo many new phis: %d  old %d new cmpi: %c",
3235                     new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
3236     }
3237 #endif
3238     if (new_peel_if != NULL) {
3239       remove_cmpi_loop_exit(new_peel_if, loop);
3240     }
3241     // Inhibit more partial peeling on this loop
3242     assert(!head->is_partial_peel_loop(), "not partial peeled");
3243     head->mark_partial_peel_failed();
3244     if (cloned_for_outside_use > 0) {
3245       // Terminate this round of loop opts because
3246       // the graph outside this loop was changed.
3247       C->set_major_progress();
3248       return true;
3249     }
3250     return false;
3251   }
3252 
3253   // Step 3: clone loop, retarget control, and insert new phis
3254 
3255   // Create new loop head for new phis and to hang
3256   // the nodes being moved (sinked) from the peel region.
3257   LoopNode* new_head = new LoopNode(last_peel, last_peel);
3258   new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3259   _igvn.register_new_node_with_optimizer(new_head);
3260   assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3261   _igvn.replace_input_of(first_not_peeled, 0, new_head);
3262   set_loop(new_head, loop);
3263   loop->_body.push(new_head);
3264   not_peel.set(new_head->_idx);
3265   set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3266   set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
3267 
3268   while (sink_list.size() > 0) {
3269     Node* n = sink_list.pop();
3270     set_ctrl(n, new_head);
3271   }
3272 
3273   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3274 
3275   clone_loop(loop, old_new, dd, IgnoreStripMined);
3276 
3277   const uint clone_exit_idx = 1;
3278   const uint orig_exit_idx  = 2;
3279   assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
3280 
3281   Node* head_clone             = old_new[head->_idx];
3282   LoopNode* new_head_clone     = old_new[new_head->_idx]->as_Loop();
3283   Node* orig_tail_clone        = head_clone->in(2);
3284 
3285   // Add phi if "def" node is in peel set and "use" is not
3286 
3287   for(i = 0; i < peel_list.size(); i++ ) {
3288     Node *def  = peel_list.at(i);
3289     if (!def->is_CFG()) {
3290       for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3291         Node *use = def->fast_out(j);
3292         if (has_node(use) && use->in(0) != C->top() &&
3293             (!peel.test(use->_idx) ||
3294              (use->is_Phi() && use->in(0) == head)) ) {
3295           worklist.push(use);
3296         }
3297       }
3298       while( worklist.size() ) {
3299         Node *use = worklist.pop();
3300         for (uint j = 1; j < use->req(); j++) {
3301           Node* n = use->in(j);
3302           if (n == def) {
3303 
3304             // "def" is in peel set, "use" is not in peel set
3305             // or "use" is in the entry boundary (a phi) of the peel set
3306 
3307             Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
3308 
3309             if ( loop->is_member(get_loop( use_c )) ) {
3310               // use is in loop
3311               if (old_new[use->_idx] != NULL) { // null for dead code
3312                 Node* use_clone = old_new[use->_idx];
3313                 _igvn.replace_input_of(use, j, C->top());
3314                 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
3315               }
3316             } else {
3317               assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
3318               // use is not in the loop, check if the live range includes the cut
3319               Node* lp_if = use_c->in(orig_exit_idx)->in(0);
3320               if (not_peel.test(lp_if->_idx)) {
3321                 assert(j == orig_exit_idx, "use from original loop");
3322                 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3323               }
3324             }
3325           }
3326         }
3327       }
3328     }
3329   }
3330 
3331   // Step 3b: retarget control
3332 
3333   // Redirect control to the new loop head if a cloned node in
3334   // the not_peeled region has control that points into the peeled region.
3335   // This necessary because the cloned peeled region will be outside
3336   // the loop.
3337   //                            from    to
3338   //          cloned-peeled    <---+
3339   //    new_head_clone:            |    <--+
3340   //          cloned-not_peeled  in(0)    in(0)
3341   //          orig-peeled
3342 
3343   for(i = 0; i < loop->_body.size(); i++ ) {
3344     Node *n = loop->_body.at(i);
3345     if (!n->is_CFG()           && n->in(0) != NULL        &&
3346         not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3347       Node* n_clone = old_new[n->_idx];
3348       _igvn.replace_input_of(n_clone, 0, new_head_clone);
3349     }
3350   }
3351 
3352   // Backedge of the surviving new_head (the clone) is original last_peel
3353   _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3354 
3355   // Cut first node in original not_peel set
3356   _igvn.rehash_node_delayed(new_head);                     // Multiple edge updates:
3357   new_head->set_req(LoopNode::EntryControl,    C->top());  //   use rehash_node_delayed / set_req instead of
3358   new_head->set_req(LoopNode::LoopBackControl, C->top());  //   multiple replace_input_of calls
3359 
3360   // Copy head_clone back-branch info to original head
3361   // and remove original head's loop entry and
3362   // clone head's back-branch
3363   _igvn.rehash_node_delayed(head); // Multiple edge updates
3364   head->set_req(LoopNode::EntryControl,    head_clone->in(LoopNode::LoopBackControl));
3365   head->set_req(LoopNode::LoopBackControl, C->top());
3366   _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3367 
3368   // Similarly modify the phis
3369   for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3370     Node* use = head->fast_out(k);
3371     if (use->is_Phi() && use->outcnt() > 0) {
3372       Node* use_clone = old_new[use->_idx];
3373       _igvn.rehash_node_delayed(use); // Multiple edge updates
3374       use->set_req(LoopNode::EntryControl,    use_clone->in(LoopNode::LoopBackControl));
3375       use->set_req(LoopNode::LoopBackControl, C->top());
3376       _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3377     }
3378   }
3379 
3380   // Step 4: update dominator tree and dominator depth
3381 
3382   set_idom(head, orig_tail_clone, dd);
3383   recompute_dom_depth();
3384 
3385   // Inhibit more partial peeling on this loop
3386   new_head_clone->set_partial_peel_loop();
3387   C->set_major_progress();
3388   loop->record_for_igvn();
3389 
3390 #ifndef PRODUCT
3391   if (TracePartialPeeling) {
3392     tty->print_cr("\nafter partial peel one iteration");
3393     Node_List wl(area);
3394     Node* t = last_peel;
3395     while (true) {
3396       wl.push(t);
3397       if (t == head_clone) break;
3398       t = idom(t);
3399     }
3400     while (wl.size() > 0) {
3401       Node* tt = wl.pop();
3402       if (tt == head) tty->print_cr("orig head");
3403       else if (tt == new_head_clone) tty->print_cr("new head");
3404       else if (tt == head_clone) tty->print_cr("clone head");
3405       tt->dump();
3406     }
3407   }
3408 #endif
3409   return true;
3410 }
3411 
3412 //------------------------------reorg_offsets----------------------------------
3413 // Reorganize offset computations to lower register pressure.  Mostly
3414 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3415 // then alive with the post-incremented trip counter forcing an extra
3416 // register move)
3417 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3418   // Perform it only for canonical counted loops.
3419   // Loop's shape could be messed up by iteration_split_impl.
3420   if (!loop->_head->is_CountedLoop())
3421     return;
3422   if (!loop->_head->as_Loop()->is_valid_counted_loop())
3423     return;
3424 
3425   CountedLoopNode *cl = loop->_head->as_CountedLoop();
3426   CountedLoopEndNode *cle = cl->loopexit();
3427   Node *exit = cle->proj_out(false);
3428   Node *phi = cl->phi();
3429 
3430   // Check for the special case when using the pre-incremented trip-counter on
3431   // the fall-out  path (forces the pre-incremented  and post-incremented trip
3432   // counter to be live  at the same time).  Fix this by  adjusting to use the
3433   // post-increment trip counter.
3434 
3435   bool progress = true;
3436   while (progress) {
3437     progress = false;
3438     for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3439       Node* use = phi->fast_out(i);   // User of trip-counter
3440       if (!has_ctrl(use))  continue;
3441       Node *u_ctrl = get_ctrl(use);
3442       if (use->is_Phi()) {
3443         u_ctrl = NULL;
3444         for (uint j = 1; j < use->req(); j++)
3445           if (use->in(j) == phi)
3446             u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3447       }
3448       IdealLoopTree *u_loop = get_loop(u_ctrl);
3449       // Look for loop-invariant use
3450       if (u_loop == loop) continue;
3451       if (loop->is_member(u_loop)) continue;
3452       // Check that use is live out the bottom.  Assuming the trip-counter
3453       // update is right at the bottom, uses of of the loop middle are ok.
3454       if (dom_lca(exit, u_ctrl) != exit) continue;
3455       // Hit!  Refactor use to use the post-incremented tripcounter.
3456       // Compute a post-increment tripcounter.
3457       Node* c = exit;
3458       if (cl->is_strip_mined()) {
3459         IdealLoopTree* outer_loop = get_loop(cl->outer_loop());
3460         if (!outer_loop->is_member(u_loop)) {
3461           c = cl->outer_loop_exit();
3462         }
3463       }
3464       Node *opaq = new Opaque2Node(C, cle->incr());
3465       register_new_node(opaq, c);
3466       Node *neg_stride = _igvn.intcon(-cle->stride_con());
3467       set_ctrl(neg_stride, C->root());
3468       Node *post = new AddINode(opaq, neg_stride);
3469       register_new_node(post, c);
3470       _igvn.rehash_node_delayed(use);
3471       for (uint j = 1; j < use->req(); j++) {
3472         if (use->in(j) == phi)
3473           use->set_req(j, post);
3474       }
3475       // Since DU info changed, rerun loop
3476       progress = true;
3477       break;
3478     }
3479   }
3480 
3481 }