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