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