1 /*
   2  * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/barrierSet.hpp"
  27 #include "gc/shared/c2/barrierSetC2.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "memory/resourceArea.hpp"
  30 #include "opto/addnode.hpp"
  31 #include "opto/callnode.hpp"
  32 #include "opto/castnode.hpp"
  33 #include "opto/connode.hpp"
  34 #include "opto/castnode.hpp"
  35 #include "opto/divnode.hpp"
  36 #include "opto/loopnode.hpp"
  37 #include "opto/matcher.hpp"
  38 #include "opto/mulnode.hpp"
  39 #include "opto/movenode.hpp"
  40 #include "opto/opaquenode.hpp"
  41 #include "opto/rootnode.hpp"
  42 #include "opto/subnode.hpp"
  43 #include "opto/valuetypenode.hpp"
  44 #include "utilities/macros.hpp"
  45 #if INCLUDE_ZGC
  46 #include "gc/z/c2/zBarrierSetC2.hpp"
  47 #endif
  48 
  49 //=============================================================================
  50 //------------------------------split_thru_phi---------------------------------
  51 // Split Node 'n' through merge point if there is enough win.
  52 Node *PhaseIdealLoop::split_thru_phi( Node *n, Node *region, int policy ) {
  53   if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
  54     // ConvI2L may have type information on it which is unsafe to push up
  55     // so disable this for now
  56     return NULL;
  57   }
  58 
  59   // Splitting range check CastIIs through a loop induction Phi can
  60   // cause new Phis to be created that are left unrelated to the loop
  61   // induction Phi and prevent optimizations (vectorization)
  62   if (n->Opcode() == Op_CastII && n->as_CastII()->has_range_check() &&
  63       region->is_CountedLoop() && n->in(1) == region->as_CountedLoop()->phi()) {
  64     return NULL;
  65   }
  66 
  67   // Value types should not be split through Phis because they cannot be merged
  68   // through Phi nodes but each value input needs to be merged individually.
  69   if (n->is_ValueType()) {
  70     return NULL;
  71   }
  72 
  73   int wins = 0;
  74   assert(!n->is_CFG(), "");
  75   assert(region->is_Region(), "");
  76 
  77   const Type* type = n->bottom_type();
  78   const TypeOopPtr *t_oop = _igvn.type(n)->isa_oopptr();
  79   Node *phi;
  80   if (t_oop != NULL && t_oop->is_known_instance_field()) {
  81     int iid    = t_oop->instance_id();
  82     int index  = C->get_alias_index(t_oop);
  83     int offset = t_oop->offset();
  84     phi = new PhiNode(region, type, NULL, iid, index, offset);
  85   } else {
  86     phi = PhiNode::make_blank(region, n);
  87   }
  88   uint old_unique = C->unique();
  89   for (uint i = 1; i < region->req(); i++) {
  90     Node *x;
  91     Node* the_clone = NULL;
  92     if (region->in(i) == C->top()) {
  93       x = C->top();             // Dead path?  Use a dead data op
  94     } else {
  95       x = n->clone();           // Else clone up the data op
  96       the_clone = x;            // Remember for possible deletion.
  97       // Alter data node to use pre-phi inputs
  98       if (n->in(0) == region)
  99         x->set_req( 0, region->in(i) );
 100       for (uint j = 1; j < n->req(); j++) {
 101         Node *in = n->in(j);
 102         if (in->is_Phi() && in->in(0) == region)
 103           x->set_req( j, in->in(i) ); // Use pre-Phi input for the clone
 104       }
 105     }
 106     // Check for a 'win' on some paths
 107     const Type *t = x->Value(&_igvn);
 108 
 109     bool singleton = t->singleton();
 110 
 111     // A TOP singleton indicates that there are no possible values incoming
 112     // along a particular edge. In most cases, this is OK, and the Phi will
 113     // be eliminated later in an Ideal call. However, we can't allow this to
 114     // happen if the singleton occurs on loop entry, as the elimination of
 115     // the PhiNode may cause the resulting node to migrate back to a previous
 116     // loop iteration.
 117     if (singleton && t == Type::TOP) {
 118       // Is_Loop() == false does not confirm the absence of a loop (e.g., an
 119       // irreducible loop may not be indicated by an affirmative is_Loop());
 120       // therefore, the only top we can split thru a phi is on a backedge of
 121       // a loop.
 122       singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
 123     }
 124 
 125     if (singleton) {
 126       wins++;
 127       x = ((PhaseGVN&)_igvn).makecon(t);
 128     } else {
 129       // We now call Identity to try to simplify the cloned node.
 130       // Note that some Identity methods call phase->type(this).
 131       // Make sure that the type array is big enough for
 132       // our new node, even though we may throw the node away.
 133       // (Note: This tweaking with igvn only works because x is a new node.)
 134       _igvn.set_type(x, t);
 135       // If x is a TypeNode, capture any more-precise type permanently into Node
 136       // otherwise it will be not updated during igvn->transform since
 137       // igvn->type(x) is set to x->Value() already.
 138       x->raise_bottom_type(t);
 139       Node *y = _igvn.apply_identity(x);
 140       if (y != x) {
 141         wins++;
 142         x = y;
 143       } else {
 144         y = _igvn.hash_find(x);
 145         if (y) {
 146           wins++;
 147           x = y;
 148         } else {
 149           // Else x is a new node we are keeping
 150           // We do not need register_new_node_with_optimizer
 151           // because set_type has already been called.
 152           _igvn._worklist.push(x);
 153         }
 154       }
 155     }
 156     if (x != the_clone && the_clone != NULL)
 157       _igvn.remove_dead_node(the_clone);
 158     phi->set_req( i, x );
 159   }
 160   // Too few wins?
 161   if (wins <= policy) {
 162     _igvn.remove_dead_node(phi);
 163     return NULL;
 164   }
 165 
 166   // Record Phi
 167   register_new_node( phi, region );
 168 
 169   for (uint i2 = 1; i2 < phi->req(); i2++) {
 170     Node *x = phi->in(i2);
 171     // If we commoned up the cloned 'x' with another existing Node,
 172     // the existing Node picks up a new use.  We need to make the
 173     // existing Node occur higher up so it dominates its uses.
 174     Node *old_ctrl;
 175     IdealLoopTree *old_loop;
 176 
 177     if (x->is_Con()) {
 178       // Constant's control is always root.
 179       set_ctrl(x, C->root());
 180       continue;
 181     }
 182     // The occasional new node
 183     if (x->_idx >= old_unique) {     // Found a new, unplaced node?
 184       old_ctrl = NULL;
 185       old_loop = NULL;               // Not in any prior loop
 186     } else {
 187       old_ctrl = get_ctrl(x);
 188       old_loop = get_loop(old_ctrl); // Get prior loop
 189     }
 190     // New late point must dominate new use
 191     Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
 192     if (new_ctrl == old_ctrl) // Nothing is changed
 193       continue;
 194 
 195     IdealLoopTree *new_loop = get_loop(new_ctrl);
 196 
 197     // Don't move x into a loop if its uses are
 198     // outside of loop. Otherwise x will be cloned
 199     // for each use outside of this loop.
 200     IdealLoopTree *use_loop = get_loop(region);
 201     if (!new_loop->is_member(use_loop) &&
 202         (old_loop == NULL || !new_loop->is_member(old_loop))) {
 203       // Take early control, later control will be recalculated
 204       // during next iteration of loop optimizations.
 205       new_ctrl = get_early_ctrl(x);
 206       new_loop = get_loop(new_ctrl);
 207     }
 208     // Set new location
 209     set_ctrl(x, new_ctrl);
 210     // If changing loop bodies, see if we need to collect into new body
 211     if (old_loop != new_loop) {
 212       if (old_loop && !old_loop->_child)
 213         old_loop->_body.yank(x);
 214       if (!new_loop->_child)
 215         new_loop->_body.push(x);  // Collect body info
 216     }
 217   }
 218 
 219   return phi;
 220 }
 221 
 222 //------------------------------dominated_by------------------------------------
 223 // Replace the dominated test with an obvious true or false.  Place it on the
 224 // IGVN worklist for later cleanup.  Move control-dependent data Nodes on the
 225 // live path up to the dominating control.
 226 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
 227   if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
 228 
 229   // prevdom is the dominating projection of the dominating test.
 230   assert( iff->is_If(), "" );
 231   assert(iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd || iff->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
 232   int pop = prevdom->Opcode();
 233   assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
 234   if (flip) {
 235     if (pop == Op_IfTrue)
 236       pop = Op_IfFalse;
 237     else
 238       pop = Op_IfTrue;
 239   }
 240   // 'con' is set to true or false to kill the dominated test.
 241   Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
 242   set_ctrl(con, C->root()); // Constant gets a new use
 243   // Hack the dominated test
 244   _igvn.replace_input_of(iff, 1, con);
 245 
 246   // If I dont have a reachable TRUE and FALSE path following the IfNode then
 247   // I can assume this path reaches an infinite loop.  In this case it's not
 248   // important to optimize the data Nodes - either the whole compilation will
 249   // be tossed or this path (and all data Nodes) will go dead.
 250   if (iff->outcnt() != 2) return;
 251 
 252   // Make control-dependent data Nodes on the live path (path that will remain
 253   // once the dominated IF is removed) become control-dependent on the
 254   // dominating projection.
 255   Node* dp = iff->as_If()->proj_out_or_null(pop == Op_IfTrue);
 256 
 257   // Loop predicates may have depending checks which should not
 258   // be skipped. For example, range check predicate has two checks
 259   // for lower and upper bounds.
 260   if (dp == NULL)
 261     return;
 262 
 263   ProjNode* dp_proj  = dp->as_Proj();
 264   ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
 265   if (exclude_loop_predicate &&
 266       (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
 267        unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != NULL ||
 268        unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
 269     // If this is a range check (IfNode::is_range_check), do not
 270     // reorder because Compile::allow_range_check_smearing might have
 271     // changed the check.
 272     return; // Let IGVN transformation change control dependence.
 273   }
 274 
 275   IdealLoopTree *old_loop = get_loop(dp);
 276 
 277   for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
 278     Node* cd = dp->fast_out(i); // Control-dependent node
 279     if (cd->depends_only_on_test()) {
 280       assert(cd->in(0) == dp, "");
 281       _igvn.replace_input_of(cd, 0, prevdom);
 282       set_early_ctrl(cd);
 283       IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
 284       if (old_loop != new_loop) {
 285         if (!old_loop->_child) old_loop->_body.yank(cd);
 286         if (!new_loop->_child) new_loop->_body.push(cd);
 287       }
 288       --i;
 289       --imax;
 290     }
 291   }
 292 }
 293 
 294 //------------------------------has_local_phi_input----------------------------
 295 // Return TRUE if 'n' has Phi inputs from its local block and no other
 296 // block-local inputs (all non-local-phi inputs come from earlier blocks)
 297 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
 298   Node *n_ctrl = get_ctrl(n);
 299   // See if some inputs come from a Phi in this block, or from before
 300   // this block.
 301   uint i;
 302   for( i = 1; i < n->req(); i++ ) {
 303     Node *phi = n->in(i);
 304     if( phi->is_Phi() && phi->in(0) == n_ctrl )
 305       break;
 306   }
 307   if( i >= n->req() )
 308     return NULL;                // No Phi inputs; nowhere to clone thru
 309 
 310   // Check for inputs created between 'n' and the Phi input.  These
 311   // must split as well; they have already been given the chance
 312   // (courtesy of a post-order visit) and since they did not we must
 313   // recover the 'cost' of splitting them by being very profitable
 314   // when splitting 'n'.  Since this is unlikely we simply give up.
 315   for( i = 1; i < n->req(); i++ ) {
 316     Node *m = n->in(i);
 317     if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
 318       // We allow the special case of AddP's with no local inputs.
 319       // This allows us to split-up address expressions.
 320       if (m->is_AddP() &&
 321           get_ctrl(m->in(2)) != n_ctrl &&
 322           get_ctrl(m->in(3)) != n_ctrl) {
 323         // Move the AddP up to dominating point
 324         Node* c = find_non_split_ctrl(idom(n_ctrl));
 325         if (c->is_OuterStripMinedLoop()) {
 326           c->as_Loop()->verify_strip_mined(1);
 327           c = c->in(LoopNode::EntryControl);
 328         }
 329         set_ctrl_and_loop(m, c);
 330         continue;
 331       }
 332       return NULL;
 333     }
 334     assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
 335   }
 336 
 337   return n_ctrl;
 338 }
 339 
 340 //------------------------------remix_address_expressions----------------------
 341 // Rework addressing expressions to get the most loop-invariant stuff
 342 // moved out.  We'd like to do all associative operators, but it's especially
 343 // important (common) to do address expressions.
 344 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
 345   if (!has_ctrl(n))  return NULL;
 346   Node *n_ctrl = get_ctrl(n);
 347   IdealLoopTree *n_loop = get_loop(n_ctrl);
 348 
 349   // See if 'n' mixes loop-varying and loop-invariant inputs and
 350   // itself is loop-varying.
 351 
 352   // Only interested in binary ops (and AddP)
 353   if( n->req() < 3 || n->req() > 4 ) return NULL;
 354 
 355   Node *n1_ctrl = get_ctrl(n->in(                    1));
 356   Node *n2_ctrl = get_ctrl(n->in(                    2));
 357   Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
 358   IdealLoopTree *n1_loop = get_loop( n1_ctrl );
 359   IdealLoopTree *n2_loop = get_loop( n2_ctrl );
 360   IdealLoopTree *n3_loop = get_loop( n3_ctrl );
 361 
 362   // Does one of my inputs spin in a tighter loop than self?
 363   if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
 364       (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
 365       (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
 366     return NULL;                // Leave well enough alone
 367 
 368   // Is at least one of my inputs loop-invariant?
 369   if( n1_loop == n_loop &&
 370       n2_loop == n_loop &&
 371       n3_loop == n_loop )
 372     return NULL;                // No loop-invariant inputs
 373 
 374 
 375   int n_op = n->Opcode();
 376 
 377   // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
 378   if( n_op == Op_LShiftI ) {
 379     // Scale is loop invariant
 380     Node *scale = n->in(2);
 381     Node *scale_ctrl = get_ctrl(scale);
 382     IdealLoopTree *scale_loop = get_loop(scale_ctrl );
 383     if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
 384       return NULL;
 385     const TypeInt *scale_t = scale->bottom_type()->isa_int();
 386     if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
 387       return NULL;              // Dont bother with byte/short masking
 388     // Add must vary with loop (else shift would be loop-invariant)
 389     Node *add = n->in(1);
 390     Node *add_ctrl = get_ctrl(add);
 391     IdealLoopTree *add_loop = get_loop(add_ctrl);
 392     //assert( n_loop == add_loop, "" );
 393     if( n_loop != add_loop ) return NULL;  // happens w/ evil ZKM loops
 394 
 395     // Convert I-V into I+ (0-V); same for V-I
 396     if( add->Opcode() == Op_SubI &&
 397         _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
 398       Node *zero = _igvn.intcon(0);
 399       set_ctrl(zero, C->root());
 400       Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
 401       register_new_node( neg, get_ctrl(add->in(2) ) );
 402       add = new AddINode( add->in(1), neg );
 403       register_new_node( add, add_ctrl );
 404     }
 405     if( add->Opcode() != Op_AddI ) return NULL;
 406     // See if one add input is loop invariant
 407     Node *add_var = add->in(1);
 408     Node *add_var_ctrl = get_ctrl(add_var);
 409     IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
 410     Node *add_invar = add->in(2);
 411     Node *add_invar_ctrl = get_ctrl(add_invar);
 412     IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
 413     if( add_var_loop == n_loop ) {
 414     } else if( add_invar_loop == n_loop ) {
 415       // Swap to find the invariant part
 416       add_invar = add_var;
 417       add_invar_ctrl = add_var_ctrl;
 418       add_invar_loop = add_var_loop;
 419       add_var = add->in(2);
 420       Node *add_var_ctrl = get_ctrl(add_var);
 421       IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
 422     } else                      // Else neither input is loop invariant
 423       return NULL;
 424     if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
 425       return NULL;              // No invariant part of the add?
 426 
 427     // Yes!  Reshape address expression!
 428     Node *inv_scale = new LShiftINode( add_invar, scale );
 429     Node *inv_scale_ctrl =
 430       dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
 431       add_invar_ctrl : scale_ctrl;
 432     register_new_node( inv_scale, inv_scale_ctrl );
 433     Node *var_scale = new LShiftINode( add_var, scale );
 434     register_new_node( var_scale, n_ctrl );
 435     Node *var_add = new AddINode( var_scale, inv_scale );
 436     register_new_node( var_add, n_ctrl );
 437     _igvn.replace_node( n, var_add );
 438     return var_add;
 439   }
 440 
 441   // Replace (I+V) with (V+I)
 442   if( n_op == Op_AddI ||
 443       n_op == Op_AddL ||
 444       n_op == Op_AddF ||
 445       n_op == Op_AddD ||
 446       n_op == Op_MulI ||
 447       n_op == Op_MulL ||
 448       n_op == Op_MulF ||
 449       n_op == Op_MulD ) {
 450     if( n2_loop == n_loop ) {
 451       assert( n1_loop != n_loop, "" );
 452       n->swap_edges(1, 2);
 453     }
 454   }
 455 
 456   // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
 457   // but not if I2 is a constant.
 458   if( n_op == Op_AddP ) {
 459     if( n2_loop == n_loop && n3_loop != n_loop ) {
 460       if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
 461         Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
 462         Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
 463         IdealLoopTree *n22loop = get_loop( n22_ctrl );
 464         IdealLoopTree *n23_loop = get_loop( n23_ctrl );
 465         if( n22loop != n_loop && n22loop->is_member(n_loop) &&
 466             n23_loop == n_loop ) {
 467           Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
 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, n->in(2)->in(3) );
 471           register_new_node( add2, n_ctrl );
 472           _igvn.replace_node( n, add2 );
 473           return add2;
 474         }
 475       }
 476     }
 477 
 478     // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
 479     if (n2_loop != n_loop && n3_loop == n_loop) {
 480       if (n->in(3)->Opcode() == Op_AddX) {
 481         Node *V = n->in(3)->in(1);
 482         Node *I = n->in(3)->in(2);
 483         if (is_member(n_loop,get_ctrl(V))) {
 484         } else {
 485           Node *tmp = V; V = I; I = tmp;
 486         }
 487         if (!is_member(n_loop,get_ctrl(I))) {
 488           Node *add1 = new AddPNode(n->in(1), n->in(2), I);
 489           // Stuff new AddP in the loop preheader
 490           register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
 491           Node *add2 = new AddPNode(n->in(1), add1, V);
 492           register_new_node(add2, n_ctrl);
 493           _igvn.replace_node(n, add2);
 494           return add2;
 495         }
 496       }
 497     }
 498   }
 499 
 500   return NULL;
 501 }
 502 
 503 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
 504 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
 505   assert(n->Opcode() == Op_AddI, "sanity");
 506   Node * nn = NULL;
 507   Node * in1 = n->in(1);
 508   Node * in2 = n->in(2);
 509   if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
 510     IdealLoopTree* loop_n = get_loop(get_ctrl(n));
 511     if (loop_n->_head->as_Loop()->is_valid_counted_loop() &&
 512         Matcher::match_rule_supported(Op_MulAddS2I) &&
 513         Matcher::match_rule_supported(Op_MulAddVS2VI)) {
 514       Node* mul_in1 = in1->in(1);
 515       Node* mul_in2 = in1->in(2);
 516       Node* mul_in3 = in2->in(1);
 517       Node* mul_in4 = in2->in(2);
 518       if (mul_in1->Opcode() == Op_LoadS &&
 519           mul_in2->Opcode() == Op_LoadS &&
 520           mul_in3->Opcode() == Op_LoadS &&
 521           mul_in4->Opcode() == Op_LoadS) {
 522         IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
 523         IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
 524         IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
 525         IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
 526         IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
 527         IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
 528         // All nodes should be in the same counted loop.
 529         if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
 530             loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
 531           Node* adr1 = mul_in1->in(MemNode::Address);
 532           Node* adr2 = mul_in2->in(MemNode::Address);
 533           Node* adr3 = mul_in3->in(MemNode::Address);
 534           Node* adr4 = mul_in4->in(MemNode::Address);
 535           if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
 536             if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
 537                 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
 538               nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
 539               register_new_node(nn, get_ctrl(n));
 540               _igvn.replace_node(n, nn);
 541               return nn;
 542             } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
 543                        (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
 544               nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
 545               register_new_node(nn, get_ctrl(n));
 546               _igvn.replace_node(n, nn);
 547               return nn;
 548             }
 549           }
 550         }
 551       }
 552     }
 553   }
 554   return nn;
 555 }
 556 
 557 //------------------------------conditional_move-------------------------------
 558 // Attempt to replace a Phi with a conditional move.  We have some pretty
 559 // strict profitability requirements.  All Phis at the merge point must
 560 // be converted, so we can remove the control flow.  We need to limit the
 561 // number of c-moves to a small handful.  All code that was in the side-arms
 562 // of the CFG diamond is now speculatively executed.  This code has to be
 563 // "cheap enough".  We are pretty much limited to CFG diamonds that merge
 564 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
 565 Node *PhaseIdealLoop::conditional_move( Node *region ) {
 566 
 567   assert(region->is_Region(), "sanity check");
 568   if (region->req() != 3) return NULL;
 569 
 570   // Check for CFG diamond
 571   Node *lp = region->in(1);
 572   Node *rp = region->in(2);
 573   if (!lp || !rp) return NULL;
 574   Node *lp_c = lp->in(0);
 575   if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
 576   IfNode *iff = lp_c->as_If();
 577 
 578   // Check for ops pinned in an arm of the diamond.
 579   // Can't remove the control flow in this case
 580   if (lp->outcnt() > 1) return NULL;
 581   if (rp->outcnt() > 1) return NULL;
 582 
 583   IdealLoopTree* r_loop = get_loop(region);
 584   assert(r_loop == get_loop(iff), "sanity");
 585   // Always convert to CMOVE if all results are used only outside this loop.
 586   bool used_inside_loop = (r_loop == _ltree_root);
 587 
 588   // Check profitability
 589   int cost = 0;
 590   int phis = 0;
 591   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 592     Node *out = region->fast_out(i);
 593     if (!out->is_Phi()) continue; // Ignore other control edges, etc
 594     phis++;
 595     PhiNode* phi = out->as_Phi();
 596     BasicType bt = phi->type()->basic_type();
 597     switch (bt) {
 598     case T_DOUBLE:
 599     case T_FLOAT:
 600       if (C->use_cmove()) {
 601         continue; //TODO: maybe we want to add some cost
 602       }
 603       cost += Matcher::float_cmove_cost(); // Could be very expensive
 604       break;
 605     case T_LONG: {
 606       cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
 607     }
 608     case T_INT:                 // These all CMOV fine
 609     case T_ADDRESS: {           // (RawPtr)
 610       cost++;
 611       break;
 612     }
 613     case T_NARROWOOP: // Fall through
 614     case T_OBJECT: {            // Base oops are OK, but not derived oops
 615       const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
 616       // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
 617       // CMOVE'd derived pointer?  It's a CMOVE'd derived base.  Thus
 618       // CMOVE'ing a derived pointer requires we also CMOVE the base.  If we
 619       // have a Phi for the base here that we convert to a CMOVE all is well
 620       // and good.  But if the base is dead, we'll not make a CMOVE.  Later
 621       // the allocator will have to produce a base by creating a CMOVE of the
 622       // relevant bases.  This puts the allocator in the business of
 623       // manufacturing expensive instructions, generally a bad plan.
 624       // Just Say No to Conditionally-Moved Derived Pointers.
 625       if (tp && tp->offset() != 0)
 626         return NULL;
 627       cost++;
 628       break;
 629     }
 630     default:
 631       return NULL;              // In particular, can't do memory or I/O
 632     }
 633     // Add in cost any speculative ops
 634     for (uint j = 1; j < region->req(); j++) {
 635       Node *proj = region->in(j);
 636       Node *inp = phi->in(j);
 637       if (get_ctrl(inp) == proj) { // Found local op
 638         cost++;
 639         // Check for a chain of dependent ops; these will all become
 640         // speculative in a CMOV.
 641         for (uint k = 1; k < inp->req(); k++)
 642           if (get_ctrl(inp->in(k)) == proj)
 643             cost += ConditionalMoveLimit; // Too much speculative goo
 644       }
 645     }
 646     // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
 647     // This will likely Split-If, a higher-payoff operation.
 648     for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
 649       Node* use = phi->fast_out(k);
 650       if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
 651         cost += ConditionalMoveLimit;
 652       // Is there a use inside the loop?
 653       // Note: check only basic types since CMoveP is pinned.
 654       if (!used_inside_loop && is_java_primitive(bt)) {
 655         IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
 656         if (r_loop == u_loop || r_loop->is_member(u_loop)) {
 657           used_inside_loop = true;
 658         }
 659       }
 660     }
 661   }//for
 662   Node* bol = iff->in(1);
 663   assert(bol->Opcode() == Op_Bool, "");
 664   int cmp_op = bol->in(1)->Opcode();
 665   // It is expensive to generate flags from a float compare.
 666   // Avoid duplicated float compare.
 667   if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
 668 
 669   float infrequent_prob = PROB_UNLIKELY_MAG(3);
 670   // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
 671   if (used_inside_loop) {
 672     if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
 673 
 674     // BlockLayoutByFrequency optimization moves infrequent branch
 675     // from hot path. No point in CMOV'ing in such case (110 is used
 676     // instead of 100 to take into account not exactness of float value).
 677     if (BlockLayoutByFrequency) {
 678       infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
 679     }
 680   }
 681   // Check for highly predictable branch.  No point in CMOV'ing if
 682   // we are going to predict accurately all the time.
 683   if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
 684     //keep going
 685   } else if (iff->_prob < infrequent_prob ||
 686       iff->_prob > (1.0f - infrequent_prob))
 687     return NULL;
 688 
 689   // --------------
 690   // Now replace all Phis with CMOV's
 691   Node *cmov_ctrl = iff->in(0);
 692   uint flip = (lp->Opcode() == Op_IfTrue);
 693   Node_List wq;
 694   while (1) {
 695     PhiNode* phi = NULL;
 696     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 697       Node *out = region->fast_out(i);
 698       if (out->is_Phi()) {
 699         phi = out->as_Phi();
 700         break;
 701       }
 702     }
 703     if (phi == NULL)  break;
 704     if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
 705     // Move speculative ops
 706     wq.push(phi);
 707     while (wq.size() > 0) {
 708       Node *n = wq.pop();
 709       for (uint j = 1; j < n->req(); j++) {
 710         Node* m = n->in(j);
 711         if (m != NULL && !is_dominator(get_ctrl(m), cmov_ctrl)) {
 712 #ifndef PRODUCT
 713           if (PrintOpto && VerifyLoopOptimizations) {
 714             tty->print("  speculate: ");
 715             m->dump();
 716           }
 717 #endif
 718           set_ctrl(m, cmov_ctrl);
 719           wq.push(m);
 720         }
 721       }
 722     }
 723     Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
 724     register_new_node( cmov, cmov_ctrl );
 725     _igvn.replace_node( phi, cmov );
 726 #ifndef PRODUCT
 727     if (TraceLoopOpts) {
 728       tty->print("CMOV  ");
 729       r_loop->dump_head();
 730       if (Verbose) {
 731         bol->in(1)->dump(1);
 732         cmov->dump(1);
 733       }
 734     }
 735     if (VerifyLoopOptimizations) verify();
 736 #endif
 737   }
 738 
 739   // The useless CFG diamond will fold up later; see the optimization in
 740   // RegionNode::Ideal.
 741   _igvn._worklist.push(region);
 742 
 743   return iff->in(1);
 744 }
 745 
 746 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
 747   for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
 748     Node* u = m->fast_out(i);
 749     if (u->is_CFG()) {
 750       if (u->Opcode() == Op_NeverBranch) {
 751         u = ((NeverBranchNode*)u)->proj_out(0);
 752         enqueue_cfg_uses(u, wq);
 753       } else {
 754         wq.push(u);
 755       }
 756     }
 757   }
 758 }
 759 
 760 // Try moving a store out of a loop, right before the loop
 761 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
 762   // Store has to be first in the loop body
 763   IdealLoopTree *n_loop = get_loop(n_ctrl);
 764   if (n->is_Store() && n_loop != _ltree_root &&
 765       n_loop->is_loop() && n_loop->_head->is_Loop() &&
 766       n->in(0) != NULL) {
 767     Node* address = n->in(MemNode::Address);
 768     Node* value = n->in(MemNode::ValueIn);
 769     Node* mem = n->in(MemNode::Memory);
 770     IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 771     IdealLoopTree* value_loop = get_loop(get_ctrl(value));
 772 
 773     // - address and value must be loop invariant
 774     // - memory must be a memory Phi for the loop
 775     // - Store must be the only store on this memory slice in the
 776     // loop: if there's another store following this one then value
 777     // written at iteration i by the second store could be overwritten
 778     // at iteration i+n by the first store: it's not safe to move the
 779     // first store out of the loop
 780     // - nothing must observe the memory Phi: it guarantees no read
 781     // before the store, we are also guaranteed the store post
 782     // dominates the loop head (ignoring a possible early
 783     // exit). Otherwise there would be extra Phi involved between the
 784     // loop's Phi and the store.
 785     // - there must be no early exit from the loop before the Store
 786     // (such an exit most of the time would be an extra use of the
 787     // memory Phi but sometimes is a bottom memory Phi that takes the
 788     // store as input).
 789 
 790     if (!n_loop->is_member(address_loop) &&
 791         !n_loop->is_member(value_loop) &&
 792         mem->is_Phi() && mem->in(0) == n_loop->_head &&
 793         mem->outcnt() == 1 &&
 794         mem->in(LoopNode::LoopBackControl) == n) {
 795 
 796       assert(n_loop->_tail != NULL, "need a tail");
 797       assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
 798 
 799       // Verify that there's no early exit of the loop before the store.
 800       bool ctrl_ok = false;
 801       {
 802         // Follow control from loop head until n, we exit the loop or
 803         // we reach the tail
 804         ResourceMark rm;
 805         Unique_Node_List wq;
 806         wq.push(n_loop->_head);
 807 
 808         for (uint next = 0; next < wq.size(); ++next) {
 809           Node *m = wq.at(next);
 810           if (m == n->in(0)) {
 811             ctrl_ok = true;
 812             continue;
 813           }
 814           assert(!has_ctrl(m), "should be CFG");
 815           if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
 816             ctrl_ok = false;
 817             break;
 818           }
 819           enqueue_cfg_uses(m, wq);
 820           if (wq.size() > 10) {
 821             ctrl_ok = false;
 822             break;
 823           }
 824         }
 825       }
 826       if (ctrl_ok) {
 827         // move the Store
 828         _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
 829         _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
 830         _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
 831         // Disconnect the phi now. An empty phi can confuse other
 832         // optimizations in this pass of loop opts.
 833         _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
 834         n_loop->_body.yank(mem);
 835 
 836         set_ctrl_and_loop(n, n->in(0));
 837 
 838         return n;
 839       }
 840     }
 841   }
 842   return NULL;
 843 }
 844 
 845 // Try moving a store out of a loop, right after the loop
 846 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
 847   if (n->is_Store() && n->in(0) != NULL) {
 848     Node *n_ctrl = get_ctrl(n);
 849     IdealLoopTree *n_loop = get_loop(n_ctrl);
 850     // Store must be in a loop
 851     if (n_loop != _ltree_root && !n_loop->_irreducible) {
 852       Node* address = n->in(MemNode::Address);
 853       Node* value = n->in(MemNode::ValueIn);
 854       IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 855       // address must be loop invariant
 856       if (!n_loop->is_member(address_loop)) {
 857         // Store must be last on this memory slice in the loop and
 858         // nothing in the loop must observe it
 859         Node* phi = NULL;
 860         for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 861           Node* u = n->fast_out(i);
 862           if (has_ctrl(u)) { // control use?
 863             IdealLoopTree *u_loop = get_loop(get_ctrl(u));
 864             if (!n_loop->is_member(u_loop)) {
 865               continue;
 866             }
 867             if (u->is_Phi() && u->in(0) == n_loop->_head) {
 868               assert(_igvn.type(u) == Type::MEMORY, "bad phi");
 869               // multiple phis on the same slice are possible
 870               if (phi != NULL) {
 871                 return;
 872               }
 873               phi = u;
 874               continue;
 875             }
 876           }
 877           return;
 878         }
 879         if (phi != NULL) {
 880           // Nothing in the loop before the store (next iteration)
 881           // must observe the stored value
 882           bool mem_ok = true;
 883           {
 884             ResourceMark rm;
 885             Unique_Node_List wq;
 886             wq.push(phi);
 887             for (uint next = 0; next < wq.size() && mem_ok; ++next) {
 888               Node *m = wq.at(next);
 889               for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
 890                 Node* u = m->fast_out(i);
 891                 if (u->is_Store() || u->is_Phi()) {
 892                   if (u != n) {
 893                     wq.push(u);
 894                     mem_ok = (wq.size() <= 10);
 895                   }
 896                 } else {
 897                   mem_ok = false;
 898                   break;
 899                 }
 900               }
 901             }
 902           }
 903           if (mem_ok) {
 904             // Move the store out of the loop if the LCA of all
 905             // users (except for the phi) is outside the loop.
 906             Node* hook = new Node(1);
 907             _igvn.rehash_node_delayed(phi);
 908             int count = phi->replace_edge(n, hook);
 909             assert(count > 0, "inconsistent phi");
 910 
 911             // Compute latest point this store can go
 912             Node* lca = get_late_ctrl(n, get_ctrl(n));
 913             if (n_loop->is_member(get_loop(lca))) {
 914               // LCA is in the loop - bail out
 915               _igvn.replace_node(hook, n);
 916               return;
 917             }
 918 #ifdef ASSERT
 919             if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
 920               assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
 921               n_loop->_head->as_Loop()->verify_strip_mined(1);
 922               Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
 923               IdealLoopTree* outer_loop = get_loop(outer);
 924               assert(n_loop->_parent == outer_loop, "broken loop tree");
 925               assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
 926             }
 927 #endif
 928 
 929             // Move store out of the loop
 930             _igvn.replace_node(hook, n->in(MemNode::Memory));
 931             _igvn.replace_input_of(n, 0, lca);
 932             set_ctrl_and_loop(n, lca);
 933 
 934             // Disconnect the phi now. An empty phi can confuse other
 935             // optimizations in this pass of loop opts..
 936             if (phi->in(LoopNode::LoopBackControl) == phi) {
 937               _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
 938               n_loop->_body.yank(phi);
 939             }
 940           }
 941         }
 942       }
 943     }
 944   }
 945 }
 946 
 947 //------------------------------split_if_with_blocks_pre-----------------------
 948 // Do the real work in a non-recursive function.  Data nodes want to be
 949 // cloned in the pre-order so they can feed each other nicely.
 950 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
 951   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 952   Node* bs_res = bs->split_if_pre(this, n);
 953   if (bs_res != NULL) {
 954     return bs_res;
 955   }
 956   // Cloning these guys is unlikely to win
 957   int n_op = n->Opcode();
 958   if( n_op == Op_MergeMem ) return n;
 959   if( n->is_Proj() ) return n;
 960   // Do not clone-up CmpFXXX variations, as these are always
 961   // followed by a CmpI
 962   if( n->is_Cmp() ) return n;
 963   // Attempt to use a conditional move instead of a phi/branch
 964   if( ConditionalMoveLimit > 0 && n_op == Op_Region ) {
 965     Node *cmov = conditional_move( n );
 966     if( cmov ) return cmov;
 967   }
 968   if( n->is_CFG() || n->is_LoadStore() )
 969     return n;
 970   if( n_op == Op_Opaque1 ||     // Opaque nodes cannot be mod'd
 971       n_op == Op_Opaque2 ) {
 972     if( !C->major_progress() )   // If chance of no more loop opts...
 973       _igvn._worklist.push(n);  // maybe we'll remove them
 974     return n;
 975   }
 976 
 977   if( n->is_Con() ) return n;   // No cloning for Con nodes
 978 
 979   Node *n_ctrl = get_ctrl(n);
 980   if( !n_ctrl ) return n;       // Dead node
 981 
 982   Node* res = try_move_store_before_loop(n, n_ctrl);
 983   if (res != NULL) {
 984     return n;
 985   }
 986 
 987   // Attempt to remix address expressions for loop invariants
 988   Node *m = remix_address_expressions( n );
 989   if( m ) return m;
 990 
 991   if (n_op == Op_AddI) {
 992     Node *nn = convert_add_to_muladd( n );
 993     if ( nn ) return nn;
 994   }
 995 
 996   if (n->is_ConstraintCast()) {
 997     Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
 998     // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
 999     // Node control inputs don't necessarily agree with loop control info (due to
1000     // transformations happened in between), thus additional dominance check is needed
1001     // to keep loop info valid.
1002     if (dom_cast != NULL && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1003       _igvn.replace_node(n, dom_cast);
1004       return dom_cast;
1005     }
1006   }
1007 
1008   // Determine if the Node has inputs from some local Phi.
1009   // Returns the block to clone thru.
1010   Node *n_blk = has_local_phi_input( n );
1011   if( !n_blk ) return n;
1012 
1013   // Do not clone the trip counter through on a CountedLoop
1014   // (messes up the canonical shape).
1015   if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
1016 
1017   // Check for having no control input; not pinned.  Allow
1018   // dominating control.
1019   if (n->in(0)) {
1020     Node *dom = idom(n_blk);
1021     if (dom_lca(n->in(0), dom) != n->in(0)) {
1022       return n;
1023     }
1024   }
1025   // Policy: when is it profitable.  You must get more wins than
1026   // policy before it is considered profitable.  Policy is usually 0,
1027   // so 1 win is considered profitable.  Big merges will require big
1028   // cloning, so get a larger policy.
1029   int policy = n_blk->req() >> 2;
1030 
1031   // If the loop is a candidate for range check elimination,
1032   // delay splitting through it's phi until a later loop optimization
1033   if (n_blk->is_CountedLoop()) {
1034     IdealLoopTree *lp = get_loop(n_blk);
1035     if (lp && lp->_rce_candidate) {
1036       return n;
1037     }
1038   }
1039 
1040   if (must_throttle_split_if()) return n;
1041 
1042   // Split 'n' through the merge point if it is profitable
1043   Node *phi = split_thru_phi( n, n_blk, policy );
1044   if (!phi) return n;
1045 
1046   // Found a Phi to split thru!
1047   // Replace 'n' with the new phi
1048   _igvn.replace_node( n, phi );
1049   // Moved a load around the loop, 'en-registering' something.
1050   if (n_blk->is_Loop() && n->is_Load() &&
1051       !phi->in(LoopNode::LoopBackControl)->is_Load())
1052     C->set_major_progress();
1053 
1054   return phi;
1055 }
1056 
1057 static bool merge_point_too_heavy(Compile* C, Node* region) {
1058   // Bail out if the region and its phis have too many users.
1059   int weight = 0;
1060   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1061     weight += region->fast_out(i)->outcnt();
1062   }
1063   int nodes_left = C->max_node_limit() - C->live_nodes();
1064   if (weight * 8 > nodes_left) {
1065     if (PrintOpto) {
1066       tty->print_cr("*** Split-if bails out:  %d nodes, region weight %d", C->unique(), weight);
1067     }
1068     return true;
1069   } else {
1070     return false;
1071   }
1072 }
1073 
1074 static bool merge_point_safe(Node* region) {
1075   // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1076   // having a PhiNode input. This sidesteps the dangerous case where the split
1077   // ConvI2LNode may become TOP if the input Value() does not
1078   // overlap the ConvI2L range, leaving a node which may not dominate its
1079   // uses.
1080   // A better fix for this problem can be found in the BugTraq entry, but
1081   // expediency for Mantis demands this hack.
1082   // 6855164: If the merge point has a FastLockNode with a PhiNode input, we stop
1083   // split_if_with_blocks from splitting a block because we could not move around
1084   // the FastLockNode.
1085   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1086     Node* n = region->fast_out(i);
1087     if (n->is_Phi()) {
1088       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1089         Node* m = n->fast_out(j);
1090         if (m->is_FastLock())
1091           return false;
1092 #ifdef _LP64
1093         if (m->Opcode() == Op_ConvI2L)
1094           return false;
1095         if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1096           return false;
1097         }
1098 #endif
1099       }
1100     }
1101   }
1102   return true;
1103 }
1104 
1105 
1106 //------------------------------place_near_use---------------------------------
1107 // Place some computation next to use but not inside inner loops.
1108 // For inner loop uses move it to the preheader area.
1109 Node *PhaseIdealLoop::place_near_use(Node *useblock) const {
1110   IdealLoopTree *u_loop = get_loop( useblock );
1111   if (u_loop->_irreducible) {
1112     return useblock;
1113   }
1114   if (u_loop->_child) {
1115     if (useblock == u_loop->_head && u_loop->_head->is_OuterStripMinedLoop()) {
1116       return u_loop->_head->in(LoopNode::EntryControl);
1117     }
1118     return useblock;
1119   }
1120   return u_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1121 }
1122 
1123 
1124 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1125   if (!n->is_If() || n->is_CountedLoopEnd()) {
1126     return false;
1127   }
1128   if (!n->in(0)->is_Region()) {
1129     return false;
1130   }
1131   Node* region = n->in(0);
1132   Node* dom = idom(region);
1133   if (!dom->is_If() || dom->in(1) != n->in(1)) {
1134     return false;
1135   }
1136   IfNode* dom_if = dom->as_If();
1137   Node* proj_true = dom_if->proj_out(1);
1138   Node* proj_false = dom_if->proj_out(0);
1139 
1140   for (uint i = 1; i < region->req(); i++) {
1141     if (is_dominator(proj_true, region->in(i))) {
1142       continue;
1143     }
1144     if (is_dominator(proj_false, region->in(i))) {
1145       continue;
1146     }
1147     return false;
1148   }
1149 
1150   return true;
1151 }
1152 
1153 
1154 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1155   if (must_throttle_split_if()) {
1156     return false;
1157   }
1158 
1159   // Do not do 'split-if' if irreducible loops are present.
1160   if (_has_irreducible_loops) {
1161     return false;
1162   }
1163 
1164   if (merge_point_too_heavy(C, n_ctrl)) {
1165     return false;
1166   }
1167 
1168   // Do not do 'split-if' if some paths are dead.  First do dead code
1169   // elimination and then see if its still profitable.
1170   for (uint i = 1; i < n_ctrl->req(); i++) {
1171     if (n_ctrl->in(i) == C->top()) {
1172       return false;
1173     }
1174   }
1175 
1176   // If trying to do a 'Split-If' at the loop head, it is only
1177   // profitable if the cmp folds up on BOTH paths.  Otherwise we
1178   // risk peeling a loop forever.
1179 
1180   // CNC - Disabled for now.  Requires careful handling of loop
1181   // body selection for the cloned code.  Also, make sure we check
1182   // for any input path not being in the same loop as n_ctrl.  For
1183   // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1184   // because the alternative loop entry points won't be converted
1185   // into LoopNodes.
1186   IdealLoopTree *n_loop = get_loop(n_ctrl);
1187   for (uint j = 1; j < n_ctrl->req(); j++) {
1188     if (get_loop(n_ctrl->in(j)) != n_loop) {
1189       return false;
1190     }
1191   }
1192 
1193   // Check for safety of the merge point.
1194   if (!merge_point_safe(n_ctrl)) {
1195     return false;
1196   }
1197 
1198   return true;
1199 }
1200 
1201 // Detect if the node is the inner strip-mined loop
1202 // Return: NULL if it's not the case, or the exit of outer strip-mined loop
1203 static Node* is_inner_of_stripmined_loop(const Node* out) {
1204   Node* out_le = NULL;
1205 
1206   if (out->is_CountedLoopEnd()) {
1207       const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1208 
1209       if (loop != NULL && loop->is_strip_mined()) {
1210         out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1211       }
1212   }
1213 
1214   return out_le;
1215 }
1216 
1217 bool PhaseIdealLoop::flatten_array_element_type_check(Node *n) {
1218   // If the CmpP is a subtype check for a value that has just been
1219   // loaded from an array, the subtype checks guarantees the value
1220   // can't be stored in a flattened array and the load of the value
1221   // happens with a flattened array check then: push the type check
1222   // through the phi of the flattened array check. This needs special
1223   // logic because the subtype check's input is not a phi but a
1224   // LoadKlass that must first be cloned through the phi.
1225   if (n->Opcode() != Op_CmpP) {
1226     return false;
1227   }
1228   
1229   Node* klassptr = n->in(1);
1230   Node* klasscon = n->in(2);
1231 
1232   if (klassptr->is_DecodeNarrowPtr()) {
1233     klassptr = klassptr->in(1);
1234   }
1235   
1236   if (klassptr->Opcode() != Op_LoadKlass && klassptr->Opcode() != Op_LoadNKlass) {
1237     return false;
1238   }
1239   
1240   if (!klasscon->is_Con()) {
1241     return false;
1242   }
1243   
1244   Node* addr = klassptr->in(MemNode::Address);
1245   
1246   if (!addr->is_AddP()) {
1247     return false;
1248   }
1249   
1250   intptr_t offset;
1251   Node* obj = AddPNode::Ideal_base_and_offset(addr, &_igvn, offset);
1252   assert(obj != NULL && addr->in(AddPNode::Base) == addr->in(AddPNode::Address), "malformed AddP?");
1253   if (obj->Opcode() == Op_CastPP) {
1254     obj = obj->in(1);
1255   }
1256 
1257   if (!obj->is_Phi()) {
1258     return false;
1259   }
1260 
1261   Node* region = obj->in(0);
1262   
1263   Node* phi = PhiNode::make_blank(region, n->in(1));
1264   for (uint i = 1; i < region->req(); i++) {
1265     Node* in = obj->in(i);
1266     Node* ctrl = get_ctrl(in);
1267     if (addr->in(AddPNode::Base) != obj) {
1268       Node* cast = addr->in(AddPNode::Base);
1269       assert(cast->Opcode() == Op_CastPP && cast->in(0) != NULL, "inconsistent subgraph");
1270       Node* cast_clone = cast->clone();
1271       cast_clone->set_req(0, region->in(i));
1272       cast_clone->set_req(1, in);
1273       register_new_node(cast_clone, region->in(i));
1274       _igvn.set_type(cast_clone, cast_clone->Value(&_igvn));
1275       in = cast_clone;
1276     }
1277     Node* addr_clone = addr->clone();
1278     addr_clone->set_req(AddPNode::Base, in);
1279     addr_clone->set_req(AddPNode::Address, in);
1280     register_new_node(addr_clone, ctrl);
1281     _igvn.set_type(addr_clone, addr_clone->Value(&_igvn));
1282     Node* klassptr_clone = klassptr->clone();
1283     klassptr_clone->set_req(2, addr_clone);
1284     register_new_node(klassptr_clone, ctrl);
1285     _igvn.set_type(klassptr_clone, klassptr_clone->Value(&_igvn));
1286     if (klassptr != n->in(1)) {
1287       Node* decode = n->in(1);
1288       assert(decode->is_DecodeNarrowPtr(), "inconcistent subgraph");
1289       Node* decode_clone = decode->clone();
1290       decode_clone->set_req(1, klassptr_clone);
1291       register_new_node(decode_clone, ctrl);
1292       _igvn.set_type(decode_clone, decode_clone->Value(&_igvn));
1293       klassptr_clone = decode_clone;
1294     }
1295     phi->set_req(i, klassptr_clone);
1296   }
1297   register_new_node(phi, region);
1298   Node* orig = n->in(1);
1299   _igvn.replace_input_of(n, 1, phi);
1300   split_if_with_blocks_post(n);
1301   if (n->outcnt() != 0) {
1302     _igvn.replace_input_of(n, 1, orig);
1303     _igvn._worklist.push(phi);
1304   }
1305   return true;
1306 }
1307 
1308 //------------------------------split_if_with_blocks_post----------------------
1309 // Do the real work in a non-recursive function.  CFG hackery wants to be
1310 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1311 // info.
1312 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1313 
1314   if (flatten_array_element_type_check(n)) {
1315     return;
1316   }
1317   
1318   // Cloning Cmp through Phi's involves the split-if transform.
1319   // FastLock is not used by an If
1320   if (n->is_Cmp() && !n->is_FastLock()) {
1321     Node *n_ctrl = get_ctrl(n);
1322     // Determine if the Node has inputs from some local Phi.
1323     // Returns the block to clone thru.
1324     Node *n_blk = has_local_phi_input(n);
1325     if (n_blk != n_ctrl) {
1326       return;
1327     }
1328 
1329     if (!can_split_if(n_ctrl)) {
1330       return;
1331     }
1332 
1333     if (n->outcnt() != 1) {
1334       return; // Multiple bool's from 1 compare?
1335     }
1336     Node *bol = n->unique_out();
1337     assert(bol->is_Bool(), "expect a bool here");
1338     if (bol->outcnt() != 1) {
1339       return;// Multiple branches from 1 compare?
1340     }
1341     Node *iff = bol->unique_out();
1342 
1343     // Check some safety conditions
1344     if (iff->is_If()) {        // Classic split-if?
1345       if (iff->in(0) != n_ctrl) {
1346         return; // Compare must be in same blk as if
1347       }
1348     } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1349       // Can't split CMove with different control edge.
1350       if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) {
1351         return;
1352       }
1353       if (get_ctrl(iff->in(2)) == n_ctrl ||
1354           get_ctrl(iff->in(3)) == n_ctrl) {
1355         return;                 // Inputs not yet split-up
1356       }
1357       if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1358         return;                 // Loop-invar test gates loop-varying CMOVE
1359       }
1360     } else {
1361       return;  // some other kind of node, such as an Allocate
1362     }
1363 
1364     // When is split-if profitable?  Every 'win' on means some control flow
1365     // goes dead, so it's almost always a win.
1366     int policy = 0;
1367     // Split compare 'n' through the merge point if it is profitable
1368     Node *phi = split_thru_phi( n, n_ctrl, policy);
1369     if (!phi) {
1370       return;
1371     }
1372 
1373     // Found a Phi to split thru!
1374     // Replace 'n' with the new phi
1375     _igvn.replace_node(n, phi);
1376 
1377     // Now split the bool up thru the phi
1378     Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1379     guarantee(bolphi != NULL, "null boolean phi node");
1380 
1381     _igvn.replace_node(bol, bolphi);
1382     assert(iff->in(1) == bolphi, "");
1383 
1384     if (bolphi->Value(&_igvn)->singleton()) {
1385       return;
1386     }
1387 
1388     // Conditional-move?  Must split up now
1389     if (!iff->is_If()) {
1390       Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1391       _igvn.replace_node(iff, cmovphi);
1392       return;
1393     }
1394 
1395     // Now split the IF
1396     do_split_if(iff);
1397     return;
1398   }
1399 
1400   // Two identical ifs back to back can be merged
1401   if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1402     Node *n_ctrl = n->in(0);
1403     PhiNode* bolphi = PhiNode::make_blank(n_ctrl, n->in(1));
1404     IfNode* dom_if = idom(n_ctrl)->as_If();
1405     Node* proj_true = dom_if->proj_out(1);
1406     Node* proj_false = dom_if->proj_out(0);
1407     Node* con_true = _igvn.makecon(TypeInt::ONE);
1408     Node* con_false = _igvn.makecon(TypeInt::ZERO);
1409 
1410     for (uint i = 1; i < n_ctrl->req(); i++) {
1411       if (is_dominator(proj_true, n_ctrl->in(i))) {
1412         bolphi->init_req(i, con_true);
1413       } else {
1414         assert(is_dominator(proj_false, n_ctrl->in(i)), "bad if");
1415         bolphi->init_req(i, con_false);
1416       }
1417     }
1418     register_new_node(bolphi, n_ctrl);
1419     _igvn.replace_input_of(n, 1, bolphi);
1420 
1421     // Now split the IF
1422     do_split_if(n);
1423     return;
1424   }
1425 
1426   // Check for an IF ready to split; one that has its
1427   // condition codes input coming from a Phi at the block start.
1428   int n_op = n->Opcode();
1429 
1430   // Check for an IF being dominated by another IF same test
1431   if (n_op == Op_If ||
1432       n_op == Op_RangeCheck) {
1433     Node *bol = n->in(1);
1434     uint max = bol->outcnt();
1435     // Check for same test used more than once?
1436     if (max > 1 && bol->is_Bool()) {
1437       // Search up IDOMs to see if this IF is dominated.
1438       Node *cutoff = get_ctrl(bol);
1439 
1440       // Now search up IDOMs till cutoff, looking for a dominating test
1441       Node *prevdom = n;
1442       Node *dom = idom(prevdom);
1443       while (dom != cutoff) {
1444         if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1445           // It's invalid to move control dependent data nodes in the inner
1446           // strip-mined loop, because:
1447           //  1) break validation of LoopNode::verify_strip_mined()
1448           //  2) move code with side-effect in strip-mined loop
1449           // Move to the exit of outer strip-mined loop in that case.
1450           Node* out_le = is_inner_of_stripmined_loop(dom);
1451           if (out_le != NULL) {
1452             prevdom = out_le;
1453           }
1454           // Replace the dominated test with an obvious true or false.
1455           // Place it on the IGVN worklist for later cleanup.
1456           C->set_major_progress();
1457           dominated_by(prevdom, n, false, true);
1458 #ifndef PRODUCT
1459           if( VerifyLoopOptimizations ) verify();
1460 #endif
1461           return;
1462         }
1463         prevdom = dom;
1464         dom = idom(prevdom);
1465       }
1466     }
1467   }
1468 
1469   // See if a shared loop-varying computation has no loop-varying uses.
1470   // Happens if something is only used for JVM state in uncommon trap exits,
1471   // like various versions of induction variable+offset.  Clone the
1472   // computation per usage to allow it to sink out of the loop.
1473   if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1474     Node *n_ctrl = get_ctrl(n);
1475     IdealLoopTree *n_loop = get_loop(n_ctrl);
1476     if( n_loop != _ltree_root ) {
1477       DUIterator_Fast imax, i = n->fast_outs(imax);
1478       for (; i < imax; i++) {
1479         Node* u = n->fast_out(i);
1480         if( !has_ctrl(u) )     break; // Found control user
1481         IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1482         if( u_loop == n_loop ) break; // Found loop-varying use
1483         if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1484         if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1485       }
1486       bool did_break = (i < imax);  // Did we break out of the previous loop?
1487       if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1488         Node *late_load_ctrl = NULL;
1489         if (n->is_Load()) {
1490           // If n is a load, get and save the result from get_late_ctrl(),
1491           // to be later used in calculating the control for n's clones.
1492           clear_dom_lca_tags();
1493           late_load_ctrl = get_late_ctrl(n, n_ctrl);
1494         }
1495         // If n is a load, and the late control is the same as the current
1496         // control, then the cloning of n is a pointless exercise, because
1497         // GVN will ensure that we end up where we started.
1498         if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1499           BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1500           for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1501             Node *u = n->last_out(j); // Clone private computation per use
1502             _igvn.rehash_node_delayed(u);
1503             Node *x = n->clone(); // Clone computation
1504             Node *x_ctrl = NULL;
1505             if( u->is_Phi() ) {
1506               // Replace all uses of normal nodes.  Replace Phi uses
1507               // individually, so the separate Nodes can sink down
1508               // different paths.
1509               uint k = 1;
1510               while( u->in(k) != n ) k++;
1511               u->set_req( k, x );
1512               // x goes next to Phi input path
1513               x_ctrl = u->in(0)->in(k);
1514               --j;
1515             } else {              // Normal use
1516               // Replace all uses
1517               for( uint k = 0; k < u->req(); k++ ) {
1518                 if( u->in(k) == n ) {
1519                   u->set_req( k, x );
1520                   --j;
1521                 }
1522               }
1523               x_ctrl = get_ctrl(u);
1524             }
1525 
1526             // Find control for 'x' next to use but not inside inner loops.
1527             // For inner loop uses get the preheader area.
1528             x_ctrl = place_near_use(x_ctrl);
1529 
1530             if (bs->sink_node(this, n, x, x_ctrl, n_ctrl)) {
1531               continue;
1532             }
1533 
1534             if (n->is_Load()) {
1535               // For loads, add a control edge to a CFG node outside of the loop
1536               // to force them to not combine and return back inside the loop
1537               // during GVN optimization (4641526).
1538               //
1539               // Because we are setting the actual control input, factor in
1540               // the result from get_late_ctrl() so we respect any
1541               // anti-dependences. (6233005).
1542               x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1543 
1544               // Don't allow the control input to be a CFG splitting node.
1545               // Such nodes should only have ProjNodes as outs, e.g. IfNode
1546               // should only have IfTrueNode and IfFalseNode (4985384).
1547               x_ctrl = find_non_split_ctrl(x_ctrl);
1548               assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1549 
1550               x->set_req(0, x_ctrl);
1551             }
1552             register_new_node(x, x_ctrl);
1553 
1554             // Some institutional knowledge is needed here: 'x' is
1555             // yanked because if the optimizer runs GVN on it all the
1556             // cloned x's will common up and undo this optimization and
1557             // be forced back in the loop.
1558             // I tried setting control edges on the x's to force them to
1559             // not combine, but the matching gets worried when it tries
1560             // to fold a StoreP and an AddP together (as part of an
1561             // address expression) and the AddP and StoreP have
1562             // different controls.
1563             if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1564           }
1565           _igvn.remove_dead_node(n);
1566         }
1567       }
1568     }
1569   }
1570 
1571   try_move_store_after_loop(n);
1572 
1573   // Remove multiple allocations of the same value type
1574   if (n->is_ValueType()) {
1575     n->as_ValueType()->remove_redundant_allocations(&_igvn, this);
1576     return; // n is now dead
1577   }
1578 
1579   // Check for Opaque2's who's loop has disappeared - who's input is in the
1580   // same loop nest as their output.  Remove 'em, they are no longer useful.
1581   if( n_op == Op_Opaque2 &&
1582       n->in(1) != NULL &&
1583       get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1584     _igvn.replace_node( n, n->in(1) );
1585   }
1586 }
1587 
1588 //------------------------------split_if_with_blocks---------------------------
1589 // Check for aggressive application of 'split-if' optimization,
1590 // using basic block level info.
1591 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1592   Node* root = C->root();
1593   visited.set(root->_idx); // first, mark root as visited
1594   // Do pre-visit work for root
1595   Node* n   = split_if_with_blocks_pre(root);
1596   uint  cnt = n->outcnt();
1597   uint  i   = 0;
1598 
1599   while (true) {
1600     // Visit all children
1601     if (i < cnt) {
1602       Node* use = n->raw_out(i);
1603       ++i;
1604       if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1605         // Now do pre-visit work for this use
1606         use = split_if_with_blocks_pre(use);
1607         nstack.push(n, i); // Save parent and next use's index.
1608         n   = use;         // Process all children of current use.
1609         cnt = use->outcnt();
1610         i   = 0;
1611       }
1612     }
1613     else {
1614       // All of n's children have been processed, complete post-processing.
1615       if (cnt != 0 && !n->is_Con()) {
1616         assert(has_node(n), "no dead nodes");
1617         split_if_with_blocks_post(n);
1618       }
1619       if (must_throttle_split_if()) {
1620         nstack.clear();
1621       }
1622       if (nstack.is_empty()) {
1623         // Finished all nodes on stack.
1624         break;
1625       }
1626       // Get saved parent node and next use's index. Visit the rest of uses.
1627       n   = nstack.node();
1628       cnt = n->outcnt();
1629       i   = nstack.index();
1630       nstack.pop();
1631     }
1632   }
1633 }
1634 
1635 
1636 //=============================================================================
1637 //
1638 //                   C L O N E   A   L O O P   B O D Y
1639 //
1640 
1641 //------------------------------clone_iff--------------------------------------
1642 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1643 // "Nearly" because all Nodes have been cloned from the original in the loop,
1644 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1645 // through the Phi recursively, and return a Bool.
1646 Node* PhaseIdealLoop::clone_iff(PhiNode *phi, IdealLoopTree *loop) {
1647 
1648   // Convert this Phi into a Phi merging Bools
1649   uint i;
1650   for (i = 1; i < phi->req(); i++) {
1651     Node *b = phi->in(i);
1652     if (b->is_Phi()) {
1653       _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi(), loop));
1654     } else {
1655       assert(b->is_Bool() || b->Opcode() == Op_Opaque4, "");
1656     }
1657   }
1658 
1659   Node* n = phi->in(1);
1660   Node* sample_opaque = NULL;
1661   Node *sample_bool = NULL;
1662   if (n->Opcode() == Op_Opaque4) {
1663     sample_opaque = n;
1664     sample_bool = n->in(1);
1665     assert(sample_bool->is_Bool(), "wrong type");
1666   } else {
1667     sample_bool = n;
1668   }
1669   Node *sample_cmp = sample_bool->in(1);
1670 
1671   // Make Phis to merge the Cmp's inputs.
1672   PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
1673   PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
1674   for (i = 1; i < phi->req(); i++) {
1675     Node *n1 = sample_opaque == NULL ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
1676     Node *n2 = sample_opaque == NULL ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
1677     phi1->set_req(i, n1);
1678     phi2->set_req(i, n2);
1679     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1680     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1681   }
1682   // See if these Phis have been made before.
1683   // Register with optimizer
1684   Node *hit1 = _igvn.hash_find_insert(phi1);
1685   if (hit1) {                   // Hit, toss just made Phi
1686     _igvn.remove_dead_node(phi1); // Remove new phi
1687     assert(hit1->is_Phi(), "" );
1688     phi1 = (PhiNode*)hit1;      // Use existing phi
1689   } else {                      // Miss
1690     _igvn.register_new_node_with_optimizer(phi1);
1691   }
1692   Node *hit2 = _igvn.hash_find_insert(phi2);
1693   if (hit2) {                   // Hit, toss just made Phi
1694     _igvn.remove_dead_node(phi2); // Remove new phi
1695     assert(hit2->is_Phi(), "" );
1696     phi2 = (PhiNode*)hit2;      // Use existing phi
1697   } else {                      // Miss
1698     _igvn.register_new_node_with_optimizer(phi2);
1699   }
1700   // Register Phis with loop/block info
1701   set_ctrl(phi1, phi->in(0));
1702   set_ctrl(phi2, phi->in(0));
1703   // Make a new Cmp
1704   Node *cmp = sample_cmp->clone();
1705   cmp->set_req(1, phi1);
1706   cmp->set_req(2, phi2);
1707   _igvn.register_new_node_with_optimizer(cmp);
1708   set_ctrl(cmp, phi->in(0));
1709 
1710   // Make a new Bool
1711   Node *b = sample_bool->clone();
1712   b->set_req(1,cmp);
1713   _igvn.register_new_node_with_optimizer(b);
1714   set_ctrl(b, phi->in(0));
1715 
1716   if (sample_opaque != NULL) {
1717     Node* opaque = sample_opaque->clone();
1718     opaque->set_req(1, b);
1719     _igvn.register_new_node_with_optimizer(opaque);
1720     set_ctrl(opaque, phi->in(0));
1721     return opaque;
1722   }
1723 
1724   assert(b->is_Bool(), "");
1725   return b;
1726 }
1727 
1728 //------------------------------clone_bool-------------------------------------
1729 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1730 // "Nearly" because all Nodes have been cloned from the original in the loop,
1731 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1732 // through the Phi recursively, and return a Bool.
1733 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1734   uint i;
1735   // Convert this Phi into a Phi merging Bools
1736   for( i = 1; i < phi->req(); i++ ) {
1737     Node *b = phi->in(i);
1738     if( b->is_Phi() ) {
1739       _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1740     } else {
1741       assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1742     }
1743   }
1744 
1745   Node *sample_cmp = phi->in(1);
1746 
1747   // Make Phis to merge the Cmp's inputs.
1748   PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1749   PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1750   for( uint j = 1; j < phi->req(); j++ ) {
1751     Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1752     Node *n1, *n2;
1753     if( cmp_top->is_Cmp() ) {
1754       n1 = cmp_top->in(1);
1755       n2 = cmp_top->in(2);
1756     } else {
1757       n1 = n2 = cmp_top;
1758     }
1759     phi1->set_req( j, n1 );
1760     phi2->set_req( j, n2 );
1761     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1762     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1763   }
1764 
1765   // See if these Phis have been made before.
1766   // Register with optimizer
1767   Node *hit1 = _igvn.hash_find_insert(phi1);
1768   if( hit1 ) {                  // Hit, toss just made Phi
1769     _igvn.remove_dead_node(phi1); // Remove new phi
1770     assert( hit1->is_Phi(), "" );
1771     phi1 = (PhiNode*)hit1;      // Use existing phi
1772   } else {                      // Miss
1773     _igvn.register_new_node_with_optimizer(phi1);
1774   }
1775   Node *hit2 = _igvn.hash_find_insert(phi2);
1776   if( hit2 ) {                  // Hit, toss just made Phi
1777     _igvn.remove_dead_node(phi2); // Remove new phi
1778     assert( hit2->is_Phi(), "" );
1779     phi2 = (PhiNode*)hit2;      // Use existing phi
1780   } else {                      // Miss
1781     _igvn.register_new_node_with_optimizer(phi2);
1782   }
1783   // Register Phis with loop/block info
1784   set_ctrl(phi1, phi->in(0));
1785   set_ctrl(phi2, phi->in(0));
1786   // Make a new Cmp
1787   Node *cmp = sample_cmp->clone();
1788   cmp->set_req( 1, phi1 );
1789   cmp->set_req( 2, phi2 );
1790   _igvn.register_new_node_with_optimizer(cmp);
1791   set_ctrl(cmp, phi->in(0));
1792 
1793   assert( cmp->is_Cmp(), "" );
1794   return (CmpNode*)cmp;
1795 }
1796 
1797 //------------------------------sink_use---------------------------------------
1798 // If 'use' was in the loop-exit block, it now needs to be sunk
1799 // below the post-loop merge point.
1800 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1801   if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1802     set_ctrl(use, post_loop);
1803     for (DUIterator j = use->outs(); use->has_out(j); j++)
1804       sink_use(use->out(j), post_loop);
1805   }
1806 }
1807 
1808 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1809                                                  IdealLoopTree* loop, IdealLoopTree* outer_loop,
1810                                                  Node_List*& split_if_set, Node_List*& split_bool_set,
1811                                                  Node_List*& split_cex_set, Node_List& worklist,
1812                                                  uint new_counter, CloneLoopMode mode) {
1813   Node* nnn = old_new[old->_idx];
1814   // Copy uses to a worklist, so I can munge the def-use info
1815   // with impunity.
1816   for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1817     worklist.push(old->fast_out(j));
1818 
1819   while( worklist.size() ) {
1820     Node *use = worklist.pop();
1821     if (!has_node(use))  continue; // Ignore dead nodes
1822     if (use->in(0) == C->top())  continue;
1823     IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1824     // Check for data-use outside of loop - at least one of OLD or USE
1825     // must not be a CFG node.
1826 #ifdef ASSERT
1827     if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == NULL) {
1828       Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
1829       assert(mode == ControlAroundStripMined && use == sfpt, "missed a node");
1830     }
1831 #endif
1832     if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
1833 
1834       // If the Data use is an IF, that means we have an IF outside of the
1835       // loop that is switching on a condition that is set inside of the
1836       // loop.  Happens if people set a loop-exit flag; then test the flag
1837       // in the loop to break the loop, then test is again outside of the
1838       // loop to determine which way the loop exited.
1839       // Loop predicate If node connects to Bool node through Opaque1 node.
1840       if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use) || use->Opcode() == Op_Opaque4) {
1841         // Since this code is highly unlikely, we lazily build the worklist
1842         // of such Nodes to go split.
1843         if (!split_if_set) {
1844           ResourceArea *area = Thread::current()->resource_area();
1845           split_if_set = new Node_List(area);
1846         }
1847         split_if_set->push(use);
1848       }
1849       if (use->is_Bool()) {
1850         if (!split_bool_set) {
1851           ResourceArea *area = Thread::current()->resource_area();
1852           split_bool_set = new Node_List(area);
1853         }
1854         split_bool_set->push(use);
1855       }
1856       if (use->Opcode() == Op_CreateEx) {
1857         if (!split_cex_set) {
1858           ResourceArea *area = Thread::current()->resource_area();
1859           split_cex_set = new Node_List(area);
1860         }
1861         split_cex_set->push(use);
1862       }
1863 
1864 
1865       // Get "block" use is in
1866       uint idx = 0;
1867       while( use->in(idx) != old ) idx++;
1868       Node *prev = use->is_CFG() ? use : get_ctrl(use);
1869       assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
1870       Node *cfg = prev->_idx >= new_counter
1871         ? prev->in(2)
1872         : idom(prev);
1873       if( use->is_Phi() )     // Phi use is in prior block
1874         cfg = prev->in(idx);  // NOT in block of Phi itself
1875       if (cfg->is_top()) {    // Use is dead?
1876         _igvn.replace_input_of(use, idx, C->top());
1877         continue;
1878       }
1879 
1880       // If use is referenced through control edge... (idx == 0)
1881       if (mode == IgnoreStripMined && idx == 0) {
1882         LoopNode *head = loop->_head->as_Loop();
1883         if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
1884           // That node is outside the inner loop, leave it outside the
1885           // outer loop as well to not confuse verification code.
1886           assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
1887           _igvn.replace_input_of(use, 0, head->outer_loop_exit());
1888           continue;
1889         }
1890       }
1891 
1892       while(!outer_loop->is_member(get_loop(cfg))) {
1893         prev = cfg;
1894         cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1895       }
1896       // If the use occurs after merging several exits from the loop, then
1897       // old value must have dominated all those exits.  Since the same old
1898       // value was used on all those exits we did not need a Phi at this
1899       // merge point.  NOW we do need a Phi here.  Each loop exit value
1900       // is now merged with the peeled body exit; each exit gets its own
1901       // private Phi and those Phis need to be merged here.
1902       Node *phi;
1903       if( prev->is_Region() ) {
1904         if( idx == 0 ) {      // Updating control edge?
1905           phi = prev;         // Just use existing control
1906         } else {              // Else need a new Phi
1907           phi = PhiNode::make( prev, old );
1908           // Now recursively fix up the new uses of old!
1909           for( uint i = 1; i < prev->req(); i++ ) {
1910             worklist.push(phi); // Onto worklist once for each 'old' input
1911           }
1912         }
1913       } else {
1914         // Get new RegionNode merging old and new loop exits
1915         prev = old_new[prev->_idx];
1916         assert( prev, "just made this in step 7" );
1917         if( idx == 0) {      // Updating control edge?
1918           phi = prev;         // Just use existing control
1919         } else {              // Else need a new Phi
1920           // Make a new Phi merging data values properly
1921           phi = PhiNode::make( prev, old );
1922           phi->set_req( 1, nnn );
1923         }
1924       }
1925       // If inserting a new Phi, check for prior hits
1926       if( idx != 0 ) {
1927         Node *hit = _igvn.hash_find_insert(phi);
1928         if( hit == NULL ) {
1929           _igvn.register_new_node_with_optimizer(phi); // Register new phi
1930         } else {                                      // or
1931           // Remove the new phi from the graph and use the hit
1932           _igvn.remove_dead_node(phi);
1933           phi = hit;                                  // Use existing phi
1934         }
1935         set_ctrl(phi, prev);
1936       }
1937       // Make 'use' use the Phi instead of the old loop body exit value
1938       _igvn.replace_input_of(use, idx, phi);
1939       if( use->_idx >= new_counter ) { // If updating new phis
1940         // Not needed for correctness, but prevents a weak assert
1941         // in AddPNode from tripping (when we end up with different
1942         // base & derived Phis that will become the same after
1943         // IGVN does CSE).
1944         Node *hit = _igvn.hash_find_insert(use);
1945         if( hit )             // Go ahead and re-hash for hits.
1946           _igvn.replace_node( use, hit );
1947       }
1948 
1949       // If 'use' was in the loop-exit block, it now needs to be sunk
1950       // below the post-loop merge point.
1951       sink_use( use, prev );
1952     }
1953   }
1954 }
1955 
1956 static void clone_outer_loop_helper(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
1957                                     const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
1958                                     bool check_old_new) {
1959   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1960     Node* u = n->fast_out(j);
1961     assert(check_old_new || old_new[u->_idx] == NULL, "shouldn't have been cloned");
1962     if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == NULL)) {
1963       Node* c = phase->get_ctrl(u);
1964       IdealLoopTree* u_loop = phase->get_loop(c);
1965       assert(!loop->is_member(u_loop), "can be in outer loop or out of both loops only");
1966       if (outer_loop->is_member(u_loop)) {
1967         wq.push(u);
1968       }
1969     }
1970   }
1971 }
1972 
1973 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1974                                       IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1975                                       Node_List& extra_data_nodes) {
1976   if (head->is_strip_mined() && mode != IgnoreStripMined) {
1977     CountedLoopNode* cl = head->as_CountedLoop();
1978     Node* l = cl->outer_loop();
1979     Node* tail = cl->outer_loop_tail();
1980     IfNode* le = cl->outer_loop_end();
1981     Node* sfpt = cl->outer_safepoint();
1982     CountedLoopEndNode* cle = cl->loopexit();
1983     CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
1984     CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
1985     Node* cle_out = cle->proj_out(false);
1986 
1987     Node* new_sfpt = NULL;
1988     Node* new_cle_out = cle_out->clone();
1989     old_new.map(cle_out->_idx, new_cle_out);
1990     if (mode == CloneIncludesStripMined) {
1991       // clone outer loop body
1992       Node* new_l = l->clone();
1993       Node* new_tail = tail->clone();
1994       IfNode* new_le = le->clone()->as_If();
1995       new_sfpt = sfpt->clone();
1996 
1997       set_loop(new_l, outer_loop->_parent);
1998       set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
1999       set_loop(new_cle_out, outer_loop->_parent);
2000       set_idom(new_cle_out, new_cle, dd);
2001       set_loop(new_sfpt, outer_loop->_parent);
2002       set_idom(new_sfpt, new_cle_out, dd);
2003       set_loop(new_le, outer_loop->_parent);
2004       set_idom(new_le, new_sfpt, dd);
2005       set_loop(new_tail, outer_loop->_parent);
2006       set_idom(new_tail, new_le, dd);
2007       set_idom(new_cl, new_l, dd);
2008 
2009       old_new.map(l->_idx, new_l);
2010       old_new.map(tail->_idx, new_tail);
2011       old_new.map(le->_idx, new_le);
2012       old_new.map(sfpt->_idx, new_sfpt);
2013 
2014       new_l->set_req(LoopNode::LoopBackControl, new_tail);
2015       new_l->set_req(0, new_l);
2016       new_tail->set_req(0, new_le);
2017       new_le->set_req(0, new_sfpt);
2018       new_sfpt->set_req(0, new_cle_out);
2019       new_cle_out->set_req(0, new_cle);
2020       new_cl->set_req(LoopNode::EntryControl, new_l);
2021 
2022       _igvn.register_new_node_with_optimizer(new_l);
2023       _igvn.register_new_node_with_optimizer(new_tail);
2024       _igvn.register_new_node_with_optimizer(new_le);
2025     } else {
2026       Node *newhead = old_new[loop->_head->_idx];
2027       newhead->as_Loop()->clear_strip_mined();
2028       _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
2029       set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2030     }
2031     // Look at data node that were assigned a control in the outer
2032     // loop: they are kept in the outer loop by the safepoint so start
2033     // from the safepoint node's inputs.
2034     IdealLoopTree* outer_loop = get_loop(l);
2035     Node_Stack stack(2);
2036     stack.push(sfpt, 1);
2037     uint new_counter = C->unique();
2038     while (stack.size() > 0) {
2039       Node* n = stack.node();
2040       uint i = stack.index();
2041       while (i < n->req() &&
2042              (n->in(i) == NULL ||
2043               !has_ctrl(n->in(i)) ||
2044               get_loop(get_ctrl(n->in(i))) != outer_loop ||
2045               (old_new[n->in(i)->_idx] != NULL && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
2046         i++;
2047       }
2048       if (i < n->req()) {
2049         stack.set_index(i+1);
2050         stack.push(n->in(i), 0);
2051       } else {
2052         assert(old_new[n->_idx] == NULL || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
2053         Node* m = n == sfpt ? new_sfpt : n->clone();
2054         if (m != NULL) {
2055           for (uint i = 0; i < n->req(); i++) {
2056             if (m->in(i) != NULL && old_new[m->in(i)->_idx] != NULL) {
2057               m->set_req(i, old_new[m->in(i)->_idx]);
2058             }
2059           }
2060         } else {
2061           assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2062         }
2063         if (n != sfpt) {
2064           extra_data_nodes.push(n);
2065           _igvn.register_new_node_with_optimizer(m);
2066           assert(get_ctrl(n) == cle_out, "what other control?");
2067           set_ctrl(m, new_cle_out);
2068           old_new.map(n->_idx, m);
2069         }
2070         stack.pop();
2071       }
2072     }
2073     if (mode == CloneIncludesStripMined) {
2074       _igvn.register_new_node_with_optimizer(new_sfpt);
2075       _igvn.register_new_node_with_optimizer(new_cle_out);
2076     }
2077     // Some other transformation may have pessimistically assign some
2078     // data nodes to the outer loop. Set their control so they are out
2079     // of the outer loop.
2080     ResourceMark rm;
2081     Unique_Node_List wq;
2082     for (uint i = 0; i < extra_data_nodes.size(); i++) {
2083       Node* old = extra_data_nodes.at(i);
2084       clone_outer_loop_helper(old, loop, outer_loop, old_new, wq, this, true);
2085     }
2086     Node* new_ctrl = cl->outer_loop_exit();
2087     assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2088     for (uint i = 0; i < wq.size(); i++) {
2089       Node* n = wq.at(i);
2090       set_ctrl(n, new_ctrl);
2091       clone_outer_loop_helper(n, loop, outer_loop, old_new, wq, this, false);
2092     }
2093   } else {
2094     Node *newhead = old_new[loop->_head->_idx];
2095     set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2096   }
2097 }
2098 
2099 //------------------------------clone_loop-------------------------------------
2100 //
2101 //                   C L O N E   A   L O O P   B O D Y
2102 //
2103 // This is the basic building block of the loop optimizations.  It clones an
2104 // entire loop body.  It makes an old_new loop body mapping; with this mapping
2105 // you can find the new-loop equivalent to an old-loop node.  All new-loop
2106 // nodes are exactly equal to their old-loop counterparts, all edges are the
2107 // same.  All exits from the old-loop now have a RegionNode that merges the
2108 // equivalent new-loop path.  This is true even for the normal "loop-exit"
2109 // condition.  All uses of loop-invariant old-loop values now come from (one
2110 // or more) Phis that merge their new-loop equivalents.
2111 //
2112 // This operation leaves the graph in an illegal state: there are two valid
2113 // control edges coming from the loop pre-header to both loop bodies.  I'll
2114 // definitely have to hack the graph after running this transform.
2115 //
2116 // From this building block I will further edit edges to perform loop peeling
2117 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2118 //
2119 // Parameter side_by_size_idom:
2120 //   When side_by_size_idom is NULL, the dominator tree is constructed for
2121 //      the clone loop to dominate the original.  Used in construction of
2122 //      pre-main-post loop sequence.
2123 //   When nonnull, the clone and original are side-by-side, both are
2124 //      dominated by the side_by_side_idom node.  Used in construction of
2125 //      unswitched loops.
2126 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2127                                 CloneLoopMode mode, Node* side_by_side_idom) {
2128 
2129   LoopNode* head = loop->_head->as_Loop();
2130   head->verify_strip_mined(1);
2131 
2132   if (C->do_vector_loop() && PrintOpto) {
2133     const char* mname = C->method()->name()->as_quoted_ascii();
2134     if (mname != NULL) {
2135       tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2136     }
2137   }
2138 
2139   CloneMap& cm = C->clone_map();
2140   Dict* dict = cm.dict();
2141   if (C->do_vector_loop()) {
2142     cm.set_clone_idx(cm.max_gen()+1);
2143 #ifndef PRODUCT
2144     if (PrintOpto) {
2145       tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2146       loop->dump_head();
2147     }
2148 #endif
2149   }
2150 
2151   // Step 1: Clone the loop body.  Make the old->new mapping.
2152   uint i;
2153   for( i = 0; i < loop->_body.size(); i++ ) {
2154     Node *old = loop->_body.at(i);
2155     Node *nnn = old->clone();
2156     old_new.map( old->_idx, nnn );
2157     if (C->do_vector_loop()) {
2158       cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
2159     }
2160     _igvn.register_new_node_with_optimizer(nnn);
2161   }
2162 
2163   IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2164 
2165   // Step 2: Fix the edges in the new body.  If the old input is outside the
2166   // loop use it.  If the old input is INside the loop, use the corresponding
2167   // new node instead.
2168   for( i = 0; i < loop->_body.size(); i++ ) {
2169     Node *old = loop->_body.at(i);
2170     Node *nnn = old_new[old->_idx];
2171     // Fix CFG/Loop controlling the new node
2172     if (has_ctrl(old)) {
2173       set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2174     } else {
2175       set_loop(nnn, outer_loop->_parent);
2176       if (old->outcnt() > 0) {
2177         set_idom( nnn, old_new[idom(old)->_idx], dd );
2178       }
2179     }
2180     // Correct edges to the new node
2181     for( uint j = 0; j < nnn->req(); j++ ) {
2182         Node *n = nnn->in(j);
2183         if( n ) {
2184           IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
2185           if( loop->is_member( old_in_loop ) )
2186             nnn->set_req(j, old_new[n->_idx]);
2187         }
2188     }
2189     _igvn.hash_find_insert(nnn);
2190   }
2191 
2192   ResourceArea *area = Thread::current()->resource_area();
2193   Node_List extra_data_nodes(area); // data nodes in the outer strip mined loop
2194   clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2195 
2196   // Step 3: Now fix control uses.  Loop varying control uses have already
2197   // been fixed up (as part of all input edges in Step 2).  Loop invariant
2198   // control uses must be either an IfFalse or an IfTrue.  Make a merge
2199   // point to merge the old and new IfFalse/IfTrue nodes; make the use
2200   // refer to this.
2201   Node_List worklist(area);
2202   uint new_counter = C->unique();
2203   for( i = 0; i < loop->_body.size(); i++ ) {
2204     Node* old = loop->_body.at(i);
2205     if( !old->is_CFG() ) continue;
2206 
2207     // Copy uses to a worklist, so I can munge the def-use info
2208     // with impunity.
2209     for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2210       worklist.push(old->fast_out(j));
2211 
2212     while( worklist.size() ) {  // Visit all uses
2213       Node *use = worklist.pop();
2214       if (!has_node(use))  continue; // Ignore dead nodes
2215       IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2216       if( !loop->is_member( use_loop ) && use->is_CFG() ) {
2217         // Both OLD and USE are CFG nodes here.
2218         assert( use->is_Proj(), "" );
2219         Node* nnn = old_new[old->_idx];
2220 
2221         Node* newuse = NULL;
2222         if (head->is_strip_mined() && mode != IgnoreStripMined) {
2223           CountedLoopNode* cl = head->as_CountedLoop();
2224           CountedLoopEndNode* cle = cl->loopexit();
2225           Node* cle_out = cle->proj_out_or_null(false);
2226           if (use == cle_out) {
2227             IfNode* le = cl->outer_loop_end();
2228             use = le->proj_out(false);
2229             use_loop = get_loop(use);
2230             if (mode == CloneIncludesStripMined) {
2231               nnn = old_new[le->_idx];
2232             } else {
2233               newuse = old_new[cle_out->_idx];
2234             }
2235           }
2236         }
2237         if (newuse == NULL) {
2238           newuse = use->clone();
2239         }
2240 
2241         // Clone the loop exit control projection
2242         if (C->do_vector_loop()) {
2243           cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
2244         }
2245         newuse->set_req(0,nnn);
2246         _igvn.register_new_node_with_optimizer(newuse);
2247         set_loop(newuse, use_loop);
2248         set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2249 
2250         // We need a Region to merge the exit from the peeled body and the
2251         // exit from the old loop body.
2252         RegionNode *r = new RegionNode(3);
2253         // Map the old use to the new merge point
2254         old_new.map( use->_idx, r );
2255         uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
2256         assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
2257 
2258         // The original user of 'use' uses 'r' instead.
2259         for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2260           Node* useuse = use->last_out(l);
2261           _igvn.rehash_node_delayed(useuse);
2262           uint uses_found = 0;
2263           if( useuse->in(0) == use ) {
2264             useuse->set_req(0, r);
2265             uses_found++;
2266             if( useuse->is_CFG() ) {
2267               assert( dom_depth(useuse) > dd_r, "" );
2268               set_idom(useuse, r, dom_depth(useuse));
2269             }
2270           }
2271           for( uint k = 1; k < useuse->req(); k++ ) {
2272             if( useuse->in(k) == use ) {
2273               useuse->set_req(k, r);
2274               uses_found++;
2275               if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2276                 assert(dom_depth(useuse) > dd_r , "");
2277                 set_idom(useuse, r, dom_depth(useuse));
2278               }
2279             }
2280           }
2281           l -= uses_found;    // we deleted 1 or more copies of this edge
2282         }
2283 
2284         // Now finish up 'r'
2285         r->set_req( 1, newuse );
2286         r->set_req( 2,    use );
2287         _igvn.register_new_node_with_optimizer(r);
2288         set_loop(r, use_loop);
2289         set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
2290       } // End of if a loop-exit test
2291     }
2292   }
2293 
2294   // Step 4: If loop-invariant use is not control, it must be dominated by a
2295   // loop exit IfFalse/IfTrue.  Find "proper" loop exit.  Make a Region
2296   // there if needed.  Make a Phi there merging old and new used values.
2297   Node_List *split_if_set = NULL;
2298   Node_List *split_bool_set = NULL;
2299   Node_List *split_cex_set = NULL;
2300   for( i = 0; i < loop->_body.size(); i++ ) {
2301     Node* old = loop->_body.at(i);
2302     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2303                                 split_bool_set, split_cex_set, worklist, new_counter,
2304                                 mode);
2305   }
2306 
2307   for (i = 0; i < extra_data_nodes.size(); i++) {
2308     Node* old = extra_data_nodes.at(i);
2309     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2310                                 split_bool_set, split_cex_set, worklist, new_counter,
2311                                 mode);
2312   }
2313 
2314   // Check for IFs that need splitting/cloning.  Happens if an IF outside of
2315   // the loop uses a condition set in the loop.  The original IF probably
2316   // takes control from one or more OLD Regions (which in turn get from NEW
2317   // Regions).  In any case, there will be a set of Phis for each merge point
2318   // from the IF up to where the original BOOL def exists the loop.
2319   if (split_if_set) {
2320     while (split_if_set->size()) {
2321       Node *iff = split_if_set->pop();
2322       if (iff->in(1)->is_Phi()) {
2323         Node *b = clone_iff(iff->in(1)->as_Phi(), loop);
2324         _igvn.replace_input_of(iff, 1, b);
2325       }
2326     }
2327   }
2328   if (split_bool_set) {
2329     while (split_bool_set->size()) {
2330       Node *b = split_bool_set->pop();
2331       Node *phi = b->in(1);
2332       assert(phi->is_Phi(), "");
2333       CmpNode *cmp = clone_bool((PhiNode*)phi, loop);
2334       _igvn.replace_input_of(b, 1, cmp);
2335     }
2336   }
2337   if (split_cex_set) {
2338     while (split_cex_set->size()) {
2339       Node *b = split_cex_set->pop();
2340       assert(b->in(0)->is_Region(), "");
2341       assert(b->in(1)->is_Phi(), "");
2342       assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2343       split_up(b, b->in(0), NULL);
2344     }
2345   }
2346 
2347 }
2348 
2349 
2350 //---------------------- stride_of_possible_iv -------------------------------------
2351 // Looks for an iff/bool/comp with one operand of the compare
2352 // being a cycle involving an add and a phi,
2353 // with an optional truncation (left-shift followed by a right-shift)
2354 // of the add. Returns zero if not an iv.
2355 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2356   Node* trunc1 = NULL;
2357   Node* trunc2 = NULL;
2358   const TypeInt* ttype = NULL;
2359   if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
2360     return 0;
2361   }
2362   BoolNode* bl = iff->in(1)->as_Bool();
2363   Node* cmp = bl->in(1);
2364   if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2365     return 0;
2366   }
2367   // Must have an invariant operand
2368   if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2369     return 0;
2370   }
2371   Node* add2 = NULL;
2372   Node* cmp1 = cmp->in(1);
2373   if (cmp1->is_Phi()) {
2374     // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2375     Node* phi = cmp1;
2376     for (uint i = 1; i < phi->req(); i++) {
2377       Node* in = phi->in(i);
2378       Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2379                                 &trunc1, &trunc2, &ttype);
2380       if (add && add->in(1) == phi) {
2381         add2 = add->in(2);
2382         break;
2383       }
2384     }
2385   } else {
2386     // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2387     Node* addtrunc = cmp1;
2388     Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2389                                 &trunc1, &trunc2, &ttype);
2390     if (add && add->in(1)->is_Phi()) {
2391       Node* phi = add->in(1);
2392       for (uint i = 1; i < phi->req(); i++) {
2393         if (phi->in(i) == addtrunc) {
2394           add2 = add->in(2);
2395           break;
2396         }
2397       }
2398     }
2399   }
2400   if (add2 != NULL) {
2401     const TypeInt* add2t = _igvn.type(add2)->is_int();
2402     if (add2t->is_con()) {
2403       return add2t->get_con();
2404     }
2405   }
2406   return 0;
2407 }
2408 
2409 
2410 //---------------------- stay_in_loop -------------------------------------
2411 // Return the (unique) control output node that's in the loop (if it exists.)
2412 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2413   Node* unique = NULL;
2414   if (!n) return NULL;
2415   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2416     Node* use = n->fast_out(i);
2417     if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2418       if (unique != NULL) {
2419         return NULL;
2420       }
2421       unique = use;
2422     }
2423   }
2424   return unique;
2425 }
2426 
2427 //------------------------------ register_node -------------------------------------
2428 // Utility to register node "n" with PhaseIdealLoop
2429 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
2430   _igvn.register_new_node_with_optimizer(n);
2431   loop->_body.push(n);
2432   if (n->is_CFG()) {
2433     set_loop(n, loop);
2434     set_idom(n, pred, ddepth);
2435   } else {
2436     set_ctrl(n, pred);
2437   }
2438 }
2439 
2440 //------------------------------ proj_clone -------------------------------------
2441 // Utility to create an if-projection
2442 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2443   ProjNode* c = p->clone()->as_Proj();
2444   c->set_req(0, iff);
2445   return c;
2446 }
2447 
2448 //------------------------------ short_circuit_if -------------------------------------
2449 // Force the iff control output to be the live_proj
2450 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2451   guarantee(live_proj != NULL, "null projection");
2452   int proj_con = live_proj->_con;
2453   assert(proj_con == 0 || proj_con == 1, "false or true projection");
2454   Node *con = _igvn.intcon(proj_con);
2455   set_ctrl(con, C->root());
2456   if (iff) {
2457     iff->set_req(1, con);
2458   }
2459   return con;
2460 }
2461 
2462 //------------------------------ insert_if_before_proj -------------------------------------
2463 // Insert a new if before an if projection (* - new node)
2464 //
2465 // before
2466 //           if(test)
2467 //           /     \
2468 //          v       v
2469 //    other-proj   proj (arg)
2470 //
2471 // after
2472 //           if(test)
2473 //           /     \
2474 //          /       v
2475 //         |      * proj-clone
2476 //         v          |
2477 //    other-proj      v
2478 //                * new_if(relop(cmp[IU](left,right)))
2479 //                  /  \
2480 //                 v    v
2481 //         * new-proj  proj
2482 //         (returned)
2483 //
2484 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2485   IfNode* iff = proj->in(0)->as_If();
2486   IdealLoopTree *loop = get_loop(proj);
2487   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2488   int ddepth = dom_depth(proj);
2489 
2490   _igvn.rehash_node_delayed(iff);
2491   _igvn.rehash_node_delayed(proj);
2492 
2493   proj->set_req(0, NULL);  // temporary disconnect
2494   ProjNode* proj2 = proj_clone(proj, iff);
2495   register_node(proj2, loop, iff, ddepth);
2496 
2497   Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2498   register_node(cmp, loop, proj2, ddepth);
2499 
2500   BoolNode* bol = new BoolNode(cmp, relop);
2501   register_node(bol, loop, proj2, ddepth);
2502 
2503   int opcode = iff->Opcode();
2504   assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2505   IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2506     new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2507   register_node(new_if, loop, proj2, ddepth);
2508 
2509   proj->set_req(0, new_if); // reattach
2510   set_idom(proj, new_if, ddepth);
2511 
2512   ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2513   guarantee(new_exit != NULL, "null exit node");
2514   register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2515 
2516   return new_exit;
2517 }
2518 
2519 //------------------------------ insert_region_before_proj -------------------------------------
2520 // Insert a region before an if projection (* - new node)
2521 //
2522 // before
2523 //           if(test)
2524 //          /      |
2525 //         v       |
2526 //       proj      v
2527 //               other-proj
2528 //
2529 // after
2530 //           if(test)
2531 //          /      |
2532 //         v       |
2533 // * proj-clone    v
2534 //         |     other-proj
2535 //         v
2536 // * new-region
2537 //         |
2538 //         v
2539 // *      dum_if
2540 //       /     \
2541 //      v       \
2542 // * dum-proj    v
2543 //              proj
2544 //
2545 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2546   IfNode* iff = proj->in(0)->as_If();
2547   IdealLoopTree *loop = get_loop(proj);
2548   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2549   int ddepth = dom_depth(proj);
2550 
2551   _igvn.rehash_node_delayed(iff);
2552   _igvn.rehash_node_delayed(proj);
2553 
2554   proj->set_req(0, NULL);  // temporary disconnect
2555   ProjNode* proj2 = proj_clone(proj, iff);
2556   register_node(proj2, loop, iff, ddepth);
2557 
2558   RegionNode* reg = new RegionNode(2);
2559   reg->set_req(1, proj2);
2560   register_node(reg, loop, iff, ddepth);
2561 
2562   IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2563   register_node(dum_if, loop, reg, ddepth);
2564 
2565   proj->set_req(0, dum_if); // reattach
2566   set_idom(proj, dum_if, ddepth);
2567 
2568   ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2569   register_node(dum_proj, loop, dum_if, ddepth);
2570 
2571   return reg;
2572 }
2573 
2574 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2575 // Clone a signed compare loop exit from an unsigned compare and
2576 // insert it before the unsigned cmp on the stay-in-loop path.
2577 // All new nodes inserted in the dominator tree between the original
2578 // if and it's projections.  The original if test is replaced with
2579 // a constant to force the stay-in-loop path.
2580 //
2581 // This is done to make sure that the original if and it's projections
2582 // still dominate the same set of control nodes, that the ctrl() relation
2583 // from data nodes to them is preserved, and that their loop nesting is
2584 // preserved.
2585 //
2586 // before
2587 //          if(i <u limit)    unsigned compare loop exit
2588 //         /       |
2589 //        v        v
2590 //   exit-proj   stay-in-loop-proj
2591 //
2592 // after
2593 //          if(stay-in-loop-const)  original if
2594 //         /       |
2595 //        /        v
2596 //       /  if(i <  limit)    new signed test
2597 //      /  /       |
2598 //     /  /        v
2599 //    /  /  if(i <u limit)    new cloned unsigned test
2600 //   /  /   /      |
2601 //   v  v  v       |
2602 //    region       |
2603 //        |        |
2604 //      dum-if     |
2605 //     /  |        |
2606 // ether  |        |
2607 //        v        v
2608 //   exit-proj   stay-in-loop-proj
2609 //
2610 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2611   const bool Signed   = true;
2612   const bool Unsigned = false;
2613 
2614   BoolNode* bol = if_cmpu->in(1)->as_Bool();
2615   if (bol->_test._test != BoolTest::lt) return NULL;
2616   CmpNode* cmpu = bol->in(1)->as_Cmp();
2617   if (cmpu->Opcode() != Op_CmpU) return NULL;
2618   int stride = stride_of_possible_iv(if_cmpu);
2619   if (stride == 0) return NULL;
2620 
2621   Node* lp_proj = stay_in_loop(if_cmpu, loop);
2622   guarantee(lp_proj != NULL, "null loop node");
2623 
2624   ProjNode* lp_continue = lp_proj->as_Proj();
2625   ProjNode* lp_exit     = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2626 
2627   Node* limit = NULL;
2628   if (stride > 0) {
2629     limit = cmpu->in(2);
2630   } else {
2631     limit = _igvn.makecon(TypeInt::ZERO);
2632     set_ctrl(limit, C->root());
2633   }
2634   // Create a new region on the exit path
2635   RegionNode* reg = insert_region_before_proj(lp_exit);
2636   guarantee(reg != NULL, "null region node");
2637 
2638   // Clone the if-cmpu-true-false using a signed compare
2639   BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2640   ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2641   reg->add_req(cmpi_exit);
2642 
2643   // Clone the if-cmpu-true-false
2644   BoolTest::mask rel_u = bol->_test._test;
2645   ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2646   reg->add_req(cmpu_exit);
2647 
2648   // Force original if to stay in loop.
2649   short_circuit_if(if_cmpu, lp_continue);
2650 
2651   return cmpi_exit->in(0)->as_If();
2652 }
2653 
2654 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2655 // Remove a previously inserted signed compare loop exit.
2656 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2657   Node* lp_proj = stay_in_loop(if_cmp, loop);
2658   assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2659          stay_in_loop(lp_proj, loop)->is_If() &&
2660          stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2661   Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2662   set_ctrl(con, C->root());
2663   if_cmp->set_req(1, con);
2664 }
2665 
2666 //------------------------------ scheduled_nodelist -------------------------------------
2667 // Create a post order schedule of nodes that are in the
2668 // "member" set.  The list is returned in "sched".
2669 // The first node in "sched" is the loop head, followed by
2670 // nodes which have no inputs in the "member" set, and then
2671 // followed by the nodes that have an immediate input dependence
2672 // on a node in "sched".
2673 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2674 
2675   assert(member.test(loop->_head->_idx), "loop head must be in member set");
2676   Arena *a = Thread::current()->resource_area();
2677   VectorSet visited(a);
2678   Node_Stack nstack(a, loop->_body.size());
2679 
2680   Node* n  = loop->_head;  // top of stack is cached in "n"
2681   uint idx = 0;
2682   visited.set(n->_idx);
2683 
2684   // Initially push all with no inputs from within member set
2685   for(uint i = 0; i < loop->_body.size(); i++ ) {
2686     Node *elt = loop->_body.at(i);
2687     if (member.test(elt->_idx)) {
2688       bool found = false;
2689       for (uint j = 0; j < elt->req(); j++) {
2690         Node* def = elt->in(j);
2691         if (def && member.test(def->_idx) && def != elt) {
2692           found = true;
2693           break;
2694         }
2695       }
2696       if (!found && elt != loop->_head) {
2697         nstack.push(n, idx);
2698         n = elt;
2699         assert(!visited.test(n->_idx), "not seen yet");
2700         visited.set(n->_idx);
2701       }
2702     }
2703   }
2704 
2705   // traverse out's that are in the member set
2706   while (true) {
2707     if (idx < n->outcnt()) {
2708       Node* use = n->raw_out(idx);
2709       idx++;
2710       if (!visited.test_set(use->_idx)) {
2711         if (member.test(use->_idx)) {
2712           nstack.push(n, idx);
2713           n = use;
2714           idx = 0;
2715         }
2716       }
2717     } else {
2718       // All outputs processed
2719       sched.push(n);
2720       if (nstack.is_empty()) break;
2721       n   = nstack.node();
2722       idx = nstack.index();
2723       nstack.pop();
2724     }
2725   }
2726 }
2727 
2728 
2729 //------------------------------ has_use_in_set -------------------------------------
2730 // Has a use in the vector set
2731 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2732   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2733     Node* use = n->fast_out(j);
2734     if (vset.test(use->_idx)) {
2735       return true;
2736     }
2737   }
2738   return false;
2739 }
2740 
2741 
2742 //------------------------------ has_use_internal_to_set -------------------------------------
2743 // Has use internal to the vector set (ie. not in a phi at the loop head)
2744 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2745   Node* head  = loop->_head;
2746   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2747     Node* use = n->fast_out(j);
2748     if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2749       return true;
2750     }
2751   }
2752   return false;
2753 }
2754 
2755 
2756 //------------------------------ clone_for_use_outside_loop -------------------------------------
2757 // clone "n" for uses that are outside of loop
2758 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2759   int cloned = 0;
2760   assert(worklist.size() == 0, "should be empty");
2761   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2762     Node* use = n->fast_out(j);
2763     if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2764       worklist.push(use);
2765     }
2766   }
2767   while( worklist.size() ) {
2768     Node *use = worklist.pop();
2769     if (!has_node(use) || use->in(0) == C->top()) continue;
2770     uint j;
2771     for (j = 0; j < use->req(); j++) {
2772       if (use->in(j) == n) break;
2773     }
2774     assert(j < use->req(), "must be there");
2775 
2776     // clone "n" and insert it between the inputs of "n" and the use outside the loop
2777     Node* n_clone = n->clone();
2778     _igvn.replace_input_of(use, j, n_clone);
2779     cloned++;
2780     Node* use_c;
2781     if (!use->is_Phi()) {
2782       use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2783     } else {
2784       // Use in a phi is considered a use in the associated predecessor block
2785       use_c = use->in(0)->in(j);
2786     }
2787     set_ctrl(n_clone, use_c);
2788     assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2789     get_loop(use_c)->_body.push(n_clone);
2790     _igvn.register_new_node_with_optimizer(n_clone);
2791 #ifndef PRODUCT
2792     if (TracePartialPeeling) {
2793       tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2794     }
2795 #endif
2796   }
2797   return cloned;
2798 }
2799 
2800 
2801 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2802 // clone "n" for special uses that are in the not_peeled region.
2803 // If these def-uses occur in separate blocks, the code generator
2804 // marks the method as not compilable.  For example, if a "BoolNode"
2805 // is in a different basic block than the "IfNode" that uses it, then
2806 // the compilation is aborted in the code generator.
2807 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2808                                                         VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2809   if (n->is_Phi() || n->is_Load()) {
2810     return;
2811   }
2812   assert(worklist.size() == 0, "should be empty");
2813   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2814     Node* use = n->fast_out(j);
2815     if ( not_peel.test(use->_idx) &&
2816          (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2817          use->in(1) == n)  {
2818       worklist.push(use);
2819     }
2820   }
2821   if (worklist.size() > 0) {
2822     // clone "n" and insert it between inputs of "n" and the use
2823     Node* n_clone = n->clone();
2824     loop->_body.push(n_clone);
2825     _igvn.register_new_node_with_optimizer(n_clone);
2826     set_ctrl(n_clone, get_ctrl(n));
2827     sink_list.push(n_clone);
2828     not_peel <<= n_clone->_idx;  // add n_clone to not_peel set.
2829 #ifndef PRODUCT
2830     if (TracePartialPeeling) {
2831       tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2832     }
2833 #endif
2834     while( worklist.size() ) {
2835       Node *use = worklist.pop();
2836       _igvn.rehash_node_delayed(use);
2837       for (uint j = 1; j < use->req(); j++) {
2838         if (use->in(j) == n) {
2839           use->set_req(j, n_clone);
2840         }
2841       }
2842     }
2843   }
2844 }
2845 
2846 
2847 //------------------------------ insert_phi_for_loop -------------------------------------
2848 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2849 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2850   Node *phi = PhiNode::make(lp, back_edge_val);
2851   phi->set_req(LoopNode::EntryControl, lp_entry_val);
2852   // Use existing phi if it already exists
2853   Node *hit = _igvn.hash_find_insert(phi);
2854   if( hit == NULL ) {
2855     _igvn.register_new_node_with_optimizer(phi);
2856     set_ctrl(phi, lp);
2857   } else {
2858     // Remove the new phi from the graph and use the hit
2859     _igvn.remove_dead_node(phi);
2860     phi = hit;
2861   }
2862   _igvn.replace_input_of(use, idx, phi);
2863 }
2864 
2865 #ifdef ASSERT
2866 //------------------------------ is_valid_loop_partition -------------------------------------
2867 // Validate the loop partition sets: peel and not_peel
2868 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2869                                               VectorSet& not_peel ) {
2870   uint i;
2871   // Check that peel_list entries are in the peel set
2872   for (i = 0; i < peel_list.size(); i++) {
2873     if (!peel.test(peel_list.at(i)->_idx)) {
2874       return false;
2875     }
2876   }
2877   // Check at loop members are in one of peel set or not_peel set
2878   for (i = 0; i < loop->_body.size(); i++ ) {
2879     Node *def  = loop->_body.at(i);
2880     uint di = def->_idx;
2881     // Check that peel set elements are in peel_list
2882     if (peel.test(di)) {
2883       if (not_peel.test(di)) {
2884         return false;
2885       }
2886       // Must be in peel_list also
2887       bool found = false;
2888       for (uint j = 0; j < peel_list.size(); j++) {
2889         if (peel_list.at(j)->_idx == di) {
2890           found = true;
2891           break;
2892         }
2893       }
2894       if (!found) {
2895         return false;
2896       }
2897     } else if (not_peel.test(di)) {
2898       if (peel.test(di)) {
2899         return false;
2900       }
2901     } else {
2902       return false;
2903     }
2904   }
2905   return true;
2906 }
2907 
2908 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2909 // Ensure a use outside of loop is of the right form
2910 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2911   Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2912   return (use->is_Phi() &&
2913           use_c->is_Region() && use_c->req() == 3 &&
2914           (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2915            use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2916            use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2917           loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2918 }
2919 
2920 //------------------------------ is_valid_clone_loop_form -------------------------------------
2921 // Ensure that all uses outside of loop are of the right form
2922 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2923                                                uint orig_exit_idx, uint clone_exit_idx) {
2924   uint len = peel_list.size();
2925   for (uint i = 0; i < len; i++) {
2926     Node *def = peel_list.at(i);
2927 
2928     for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2929       Node *use = def->fast_out(j);
2930       Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2931       if (!loop->is_member(get_loop(use_c))) {
2932         // use is not in the loop, check for correct structure
2933         if (use->in(0) == def) {
2934           // Okay
2935         } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2936           return false;
2937         }
2938       }
2939     }
2940   }
2941   return true;
2942 }
2943 #endif
2944 
2945 //------------------------------ partial_peel -------------------------------------
2946 // Partially peel (aka loop rotation) the top portion of a loop (called
2947 // the peel section below) by cloning it and placing one copy just before
2948 // the new loop head and the other copy at the bottom of the new loop.
2949 //
2950 //    before                       after                where it came from
2951 //
2952 //    stmt1                        stmt1
2953 //  loop:                          stmt2                     clone
2954 //    stmt2                        if condA goto exitA       clone
2955 //    if condA goto exitA        new_loop:                   new
2956 //    stmt3                        stmt3                     clone
2957 //    if !condB goto loop          if condB goto exitB       clone
2958 //  exitB:                         stmt2                     orig
2959 //    stmt4                        if !condA goto new_loop   orig
2960 //  exitA:                         goto exitA
2961 //                               exitB:
2962 //                                 stmt4
2963 //                               exitA:
2964 //
2965 // Step 1: find the cut point: an exit test on probable
2966 //         induction variable.
2967 // Step 2: schedule (with cloning) operations in the peel
2968 //         section that can be executed after the cut into
2969 //         the section that is not peeled.  This may need
2970 //         to clone operations into exit blocks.  For
2971 //         instance, a reference to A[i] in the not-peel
2972 //         section and a reference to B[i] in an exit block
2973 //         may cause a left-shift of i by 2 to be placed
2974 //         in the peel block.  This step will clone the left
2975 //         shift into the exit block and sink the left shift
2976 //         from the peel to the not-peel section.
2977 // Step 3: clone the loop, retarget the control, and insert
2978 //         phis for values that are live across the new loop
2979 //         head.  This is very dependent on the graph structure
2980 //         from clone_loop.  It creates region nodes for
2981 //         exit control and associated phi nodes for values
2982 //         flow out of the loop through that exit.  The region
2983 //         node is dominated by the clone's control projection.
2984 //         So the clone's peel section is placed before the
2985 //         new loop head, and the clone's not-peel section is
2986 //         forms the top part of the new loop.  The original
2987 //         peel section forms the tail of the new loop.
2988 // Step 4: update the dominator tree and recompute the
2989 //         dominator depth.
2990 //
2991 //                   orig
2992 //
2993 //                   stmt1
2994 //                     |
2995 //                     v
2996 //               loop predicate
2997 //                     |
2998 //                     v
2999 //                   loop<----+
3000 //                     |      |
3001 //                   stmt2    |
3002 //                     |      |
3003 //                     v      |
3004 //                    ifA     |
3005 //                   / |      |
3006 //                  v  v      |
3007 //               false true   ^  <-- last_peel
3008 //               /     |      |
3009 //              /   ===|==cut |
3010 //             /     stmt3    |  <-- first_not_peel
3011 //            /        |      |
3012 //            |        v      |
3013 //            v       ifB     |
3014 //          exitA:   / \      |
3015 //                  /   \     |
3016 //                 v     v    |
3017 //               false true   |
3018 //               /       \    |
3019 //              /         ----+
3020 //             |
3021 //             v
3022 //           exitB:
3023 //           stmt4
3024 //
3025 //
3026 //            after clone loop
3027 //
3028 //                   stmt1
3029 //                     |
3030 //                     v
3031 //               loop predicate
3032 //                 /       \
3033 //        clone   /         \   orig
3034 //               /           \
3035 //              /             \
3036 //             v               v
3037 //   +---->loop                loop<----+
3038 //   |      |                    |      |
3039 //   |    stmt2                stmt2    |
3040 //   |      |                    |      |
3041 //   |      v                    v      |
3042 //   |      ifA                 ifA     |
3043 //   |      | \                / |      |
3044 //   |      v  v              v  v      |
3045 //   ^    true  false      false true   ^  <-- last_peel
3046 //   |      |   ^   \       /    |      |
3047 //   | cut==|==  \   \     /  ===|==cut |
3048 //   |    stmt3   \   \   /    stmt3    |  <-- first_not_peel
3049 //   |      |    dom   | |       |      |
3050 //   |      v      \  1v v2      v      |
3051 //   |      ifB     regionA     ifB     |
3052 //   |      / \        |       / \      |
3053 //   |     /   \       v      /   \     |
3054 //   |    v     v    exitA:  v     v    |
3055 //   |    true  false      false true   |
3056 //   |    /     ^   \      /       \    |
3057 //   +----       \   \    /         ----+
3058 //               dom  \  /
3059 //                 \  1v v2
3060 //                  regionB
3061 //                     |
3062 //                     v
3063 //                   exitB:
3064 //                   stmt4
3065 //
3066 //
3067 //           after partial peel
3068 //
3069 //                  stmt1
3070 //                     |
3071 //                     v
3072 //               loop predicate
3073 //                 /
3074 //        clone   /             orig
3075 //               /          TOP
3076 //              /             \
3077 //             v               v
3078 //    TOP->loop                loop----+
3079 //          |                    |      |
3080 //        stmt2                stmt2    |
3081 //          |                    |      |
3082 //          v                    v      |
3083 //          ifA                 ifA     |
3084 //          | \                / |      |
3085 //          v  v              v  v      |
3086 //        true  false      false true   |     <-- last_peel
3087 //          |   ^   \       /    +------|---+
3088 //  +->newloop   \   \     /  === ==cut |   |
3089 //  |     stmt3   \   \   /     TOP     |   |
3090 //  |       |    dom   | |      stmt3   |   | <-- first_not_peel
3091 //  |       v      \  1v v2      v      |   |
3092 //  |       ifB     regionA     ifB     ^   v
3093 //  |       / \        |       / \      |   |
3094 //  |      /   \       v      /   \     |   |
3095 //  |     v     v    exitA:  v     v    |   |
3096 //  |     true  false      false true   |   |
3097 //  |     /     ^   \      /       \    |   |
3098 //  |    |       \   \    /         v   |   |
3099 //  |    |       dom  \  /         TOP  |   |
3100 //  |    |         \  1v v2             |   |
3101 //  ^    v          regionB             |   |
3102 //  |    |             |                |   |
3103 //  |    |             v                ^   v
3104 //  |    |           exitB:             |   |
3105 //  |    |           stmt4              |   |
3106 //  |    +------------>-----------------+   |
3107 //  |                                       |
3108 //  +-----------------<---------------------+
3109 //
3110 //
3111 //              final graph
3112 //
3113 //                  stmt1
3114 //                    |
3115 //                    v
3116 //               loop predicate
3117 //                    |
3118 //                    v
3119 //                  stmt2 clone
3120 //                    |
3121 //                    v
3122 //         ........> ifA clone
3123 //         :        / |
3124 //        dom      /  |
3125 //         :      v   v
3126 //         :  false   true
3127 //         :  |       |
3128 //         :  |       v
3129 //         :  |    newloop<-----+
3130 //         :  |        |        |
3131 //         :  |     stmt3 clone |
3132 //         :  |        |        |
3133 //         :  |        v        |
3134 //         :  |       ifB       |
3135 //         :  |      / \        |
3136 //         :  |     v   v       |
3137 //         :  |  false true     |
3138 //         :  |   |     |       |
3139 //         :  |   v    stmt2    |
3140 //         :  | exitB:  |       |
3141 //         :  | stmt4   v       |
3142 //         :  |       ifA orig  |
3143 //         :  |      /  \       |
3144 //         :  |     /    \      |
3145 //         :  |    v     v      |
3146 //         :  |  false  true    |
3147 //         :  |  /        \     |
3148 //         :  v  v         -----+
3149 //          RegionA
3150 //             |
3151 //             v
3152 //           exitA
3153 //
3154 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3155 
3156   assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3157   if (!loop->_head->is_Loop()) {
3158     return false;
3159   }
3160   LoopNode *head = loop->_head->as_Loop();
3161 
3162   if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3163     return false;
3164   }
3165 
3166   // Check for complex exit control
3167   for (uint ii = 0; ii < loop->_body.size(); ii++) {
3168     Node *n = loop->_body.at(ii);
3169     int opc = n->Opcode();
3170     if (n->is_Call()        ||
3171         opc == Op_Catch     ||
3172         opc == Op_CatchProj ||
3173         opc == Op_Jump      ||
3174         opc == Op_JumpProj) {
3175 #ifndef PRODUCT
3176       if (TracePartialPeeling) {
3177         tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3178       }
3179 #endif
3180       return false;
3181     }
3182   }
3183 
3184   int dd = dom_depth(head);
3185 
3186   // Step 1: find cut point
3187 
3188   // Walk up dominators to loop head looking for first loop exit
3189   // which is executed on every path thru loop.
3190   IfNode *peel_if = NULL;
3191   IfNode *peel_if_cmpu = NULL;
3192 
3193   Node *iff = loop->tail();
3194   while (iff != head) {
3195     if (iff->is_If()) {
3196       Node *ctrl = get_ctrl(iff->in(1));
3197       if (ctrl->is_top()) return false; // Dead test on live IF.
3198       // If loop-varying exit-test, check for induction variable
3199       if (loop->is_member(get_loop(ctrl)) &&
3200           loop->is_loop_exit(iff) &&
3201           is_possible_iv_test(iff)) {
3202         Node* cmp = iff->in(1)->in(1);
3203         if (cmp->Opcode() == Op_CmpI) {
3204           peel_if = iff->as_If();
3205         } else {
3206           assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3207           peel_if_cmpu = iff->as_If();
3208         }
3209       }
3210     }
3211     iff = idom(iff);
3212   }
3213 
3214   // Prefer signed compare over unsigned compare.
3215   IfNode* new_peel_if = NULL;
3216   if (peel_if == NULL) {
3217     if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
3218       return false;   // No peel point found
3219     }
3220     new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3221     if (new_peel_if == NULL) {
3222       return false;   // No peel point found
3223     }
3224     peel_if = new_peel_if;
3225   }
3226   Node* last_peel        = stay_in_loop(peel_if, loop);
3227   Node* first_not_peeled = stay_in_loop(last_peel, loop);
3228   if (first_not_peeled == NULL || first_not_peeled == head) {
3229     return false;
3230   }
3231 
3232 #ifndef PRODUCT
3233   if (TraceLoopOpts) {
3234     tty->print("PartialPeel  ");
3235     loop->dump_head();
3236   }
3237 
3238   if (TracePartialPeeling) {
3239     tty->print_cr("before partial peel one iteration");
3240     Node_List wl;
3241     Node* t = head->in(2);
3242     while (true) {
3243       wl.push(t);
3244       if (t == head) break;
3245       t = idom(t);
3246     }
3247     while (wl.size() > 0) {
3248       Node* tt = wl.pop();
3249       tt->dump();
3250       if (tt == last_peel) tty->print_cr("-- cut --");
3251     }
3252   }
3253 #endif
3254   ResourceArea *area = Thread::current()->resource_area();
3255   VectorSet peel(area);
3256   VectorSet not_peel(area);
3257   Node_List peel_list(area);
3258   Node_List worklist(area);
3259   Node_List sink_list(area);
3260 
3261   if (!may_require_nodes(loop->est_loop_clone_sz(2))) {
3262     return false;
3263   }
3264 
3265   // Set of cfg nodes to peel are those that are executable from
3266   // the head through last_peel.
3267   assert(worklist.size() == 0, "should be empty");
3268   worklist.push(head);
3269   peel.set(head->_idx);
3270   while (worklist.size() > 0) {
3271     Node *n = worklist.pop();
3272     if (n != last_peel) {
3273       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3274         Node* use = n->fast_out(j);
3275         if (use->is_CFG() &&
3276             loop->is_member(get_loop(use)) &&
3277             !peel.test_set(use->_idx)) {
3278           worklist.push(use);
3279         }
3280       }
3281     }
3282   }
3283 
3284   // Set of non-cfg nodes to peel are those that are control
3285   // dependent on the cfg nodes.
3286   uint i;
3287   for(i = 0; i < loop->_body.size(); i++ ) {
3288     Node *n = loop->_body.at(i);
3289     Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3290     if (peel.test(n_c->_idx)) {
3291       peel.set(n->_idx);
3292     } else {
3293       not_peel.set(n->_idx);
3294     }
3295   }
3296 
3297   // Step 2: move operations from the peeled section down into the
3298   //         not-peeled section
3299 
3300   // Get a post order schedule of nodes in the peel region
3301   // Result in right-most operand.
3302   scheduled_nodelist(loop, peel, peel_list );
3303 
3304   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3305 
3306   // For future check for too many new phis
3307   uint old_phi_cnt = 0;
3308   for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3309     Node* use = head->fast_out(j);
3310     if (use->is_Phi()) old_phi_cnt++;
3311   }
3312 
3313 #ifndef PRODUCT
3314   if (TracePartialPeeling) {
3315     tty->print_cr("\npeeled list");
3316   }
3317 #endif
3318 
3319   // Evacuate nodes in peel region into the not_peeled region if possible
3320   uint new_phi_cnt = 0;
3321   uint cloned_for_outside_use = 0;
3322   for (i = 0; i < peel_list.size();) {
3323     Node* n = peel_list.at(i);
3324 #ifndef PRODUCT
3325   if (TracePartialPeeling) n->dump();
3326 #endif
3327     bool incr = true;
3328     if ( !n->is_CFG() ) {
3329 
3330       if ( has_use_in_set(n, not_peel) ) {
3331 
3332         // If not used internal to the peeled region,
3333         // move "n" from peeled to not_peeled region.
3334 
3335         if ( !has_use_internal_to_set(n, peel, loop) ) {
3336 
3337           // if not pinned and not a load (which maybe anti-dependent on a store)
3338           // and not a CMove (Matcher expects only bool->cmove).
3339           if (n->in(0) == NULL && !n->is_Load() && !n->is_CMove()) {
3340             cloned_for_outside_use += clone_for_use_outside_loop( loop, n, worklist );
3341             sink_list.push(n);
3342             peel     >>= n->_idx; // delete n from peel set.
3343             not_peel <<= n->_idx; // add n to not_peel set.
3344             peel_list.remove(i);
3345             incr = false;
3346 #ifndef PRODUCT
3347             if (TracePartialPeeling) {
3348               tty->print_cr("sink to not_peeled region: %d newbb: %d",
3349                             n->_idx, get_ctrl(n)->_idx);
3350             }
3351 #endif
3352           }
3353         } else {
3354           // Otherwise check for special def-use cases that span
3355           // the peel/not_peel boundary such as bool->if
3356           clone_for_special_use_inside_loop( loop, n, not_peel, sink_list, worklist );
3357           new_phi_cnt++;
3358         }
3359       }
3360     }
3361     if (incr) i++;
3362   }
3363 
3364   if (new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta) {
3365 #ifndef PRODUCT
3366     if (TracePartialPeeling) {
3367       tty->print_cr("\nToo many new phis: %d  old %d new cmpi: %c",
3368                     new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
3369     }
3370 #endif
3371     if (new_peel_if != NULL) {
3372       remove_cmpi_loop_exit(new_peel_if, loop);
3373     }
3374     // Inhibit more partial peeling on this loop
3375     assert(!head->is_partial_peel_loop(), "not partial peeled");
3376     head->mark_partial_peel_failed();
3377     if (cloned_for_outside_use > 0) {
3378       // Terminate this round of loop opts because
3379       // the graph outside this loop was changed.
3380       C->set_major_progress();
3381       return true;
3382     }
3383     return false;
3384   }
3385 
3386   // Step 3: clone loop, retarget control, and insert new phis
3387 
3388   // Create new loop head for new phis and to hang
3389   // the nodes being moved (sinked) from the peel region.
3390   LoopNode* new_head = new LoopNode(last_peel, last_peel);
3391   new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3392   _igvn.register_new_node_with_optimizer(new_head);
3393   assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3394   _igvn.replace_input_of(first_not_peeled, 0, new_head);
3395   set_loop(new_head, loop);
3396   loop->_body.push(new_head);
3397   not_peel.set(new_head->_idx);
3398   set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3399   set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
3400 
3401   while (sink_list.size() > 0) {
3402     Node* n = sink_list.pop();
3403     set_ctrl(n, new_head);
3404   }
3405 
3406   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3407 
3408   clone_loop(loop, old_new, dd, IgnoreStripMined);
3409 
3410   const uint clone_exit_idx = 1;
3411   const uint orig_exit_idx  = 2;
3412   assert(is_valid_clone_loop_form( loop, peel_list, orig_exit_idx, clone_exit_idx ), "bad clone loop");
3413 
3414   Node* head_clone             = old_new[head->_idx];
3415   LoopNode* new_head_clone     = old_new[new_head->_idx]->as_Loop();
3416   Node* orig_tail_clone        = head_clone->in(2);
3417 
3418   // Add phi if "def" node is in peel set and "use" is not
3419 
3420   for(i = 0; i < peel_list.size(); i++ ) {
3421     Node *def  = peel_list.at(i);
3422     if (!def->is_CFG()) {
3423       for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3424         Node *use = def->fast_out(j);
3425         if (has_node(use) && use->in(0) != C->top() &&
3426             (!peel.test(use->_idx) ||
3427              (use->is_Phi() && use->in(0) == head)) ) {
3428           worklist.push(use);
3429         }
3430       }
3431       while( worklist.size() ) {
3432         Node *use = worklist.pop();
3433         for (uint j = 1; j < use->req(); j++) {
3434           Node* n = use->in(j);
3435           if (n == def) {
3436 
3437             // "def" is in peel set, "use" is not in peel set
3438             // or "use" is in the entry boundary (a phi) of the peel set
3439 
3440             Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
3441 
3442             if ( loop->is_member(get_loop( use_c )) ) {
3443               // use is in loop
3444               if (old_new[use->_idx] != NULL) { // null for dead code
3445                 Node* use_clone = old_new[use->_idx];
3446                 _igvn.replace_input_of(use, j, C->top());
3447                 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
3448               }
3449             } else {
3450               assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
3451               // use is not in the loop, check if the live range includes the cut
3452               Node* lp_if = use_c->in(orig_exit_idx)->in(0);
3453               if (not_peel.test(lp_if->_idx)) {
3454                 assert(j == orig_exit_idx, "use from original loop");
3455                 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3456               }
3457             }
3458           }
3459         }
3460       }
3461     }
3462   }
3463 
3464   // Step 3b: retarget control
3465 
3466   // Redirect control to the new loop head if a cloned node in
3467   // the not_peeled region has control that points into the peeled region.
3468   // This necessary because the cloned peeled region will be outside
3469   // the loop.
3470   //                            from    to
3471   //          cloned-peeled    <---+
3472   //    new_head_clone:            |    <--+
3473   //          cloned-not_peeled  in(0)    in(0)
3474   //          orig-peeled
3475 
3476   for(i = 0; i < loop->_body.size(); i++ ) {
3477     Node *n = loop->_body.at(i);
3478     if (!n->is_CFG()           && n->in(0) != NULL        &&
3479         not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3480       Node* n_clone = old_new[n->_idx];
3481       _igvn.replace_input_of(n_clone, 0, new_head_clone);
3482     }
3483   }
3484 
3485   // Backedge of the surviving new_head (the clone) is original last_peel
3486   _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3487 
3488   // Cut first node in original not_peel set
3489   _igvn.rehash_node_delayed(new_head);                     // Multiple edge updates:
3490   new_head->set_req(LoopNode::EntryControl,    C->top());  //   use rehash_node_delayed / set_req instead of
3491   new_head->set_req(LoopNode::LoopBackControl, C->top());  //   multiple replace_input_of calls
3492 
3493   // Copy head_clone back-branch info to original head
3494   // and remove original head's loop entry and
3495   // clone head's back-branch
3496   _igvn.rehash_node_delayed(head); // Multiple edge updates
3497   head->set_req(LoopNode::EntryControl,    head_clone->in(LoopNode::LoopBackControl));
3498   head->set_req(LoopNode::LoopBackControl, C->top());
3499   _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3500 
3501   // Similarly modify the phis
3502   for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3503     Node* use = head->fast_out(k);
3504     if (use->is_Phi() && use->outcnt() > 0) {
3505       Node* use_clone = old_new[use->_idx];
3506       _igvn.rehash_node_delayed(use); // Multiple edge updates
3507       use->set_req(LoopNode::EntryControl,    use_clone->in(LoopNode::LoopBackControl));
3508       use->set_req(LoopNode::LoopBackControl, C->top());
3509       _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3510     }
3511   }
3512 
3513   // Step 4: update dominator tree and dominator depth
3514 
3515   set_idom(head, orig_tail_clone, dd);
3516   recompute_dom_depth();
3517 
3518   // Inhibit more partial peeling on this loop
3519   new_head_clone->set_partial_peel_loop();
3520   C->set_major_progress();
3521   loop->record_for_igvn();
3522 
3523 #ifndef PRODUCT
3524   if (TracePartialPeeling) {
3525     tty->print_cr("\nafter partial peel one iteration");
3526     Node_List wl(area);
3527     Node* t = last_peel;
3528     while (true) {
3529       wl.push(t);
3530       if (t == head_clone) break;
3531       t = idom(t);
3532     }
3533     while (wl.size() > 0) {
3534       Node* tt = wl.pop();
3535       if (tt == head) tty->print_cr("orig head");
3536       else if (tt == new_head_clone) tty->print_cr("new head");
3537       else if (tt == head_clone) tty->print_cr("clone head");
3538       tt->dump();
3539     }
3540   }
3541 #endif
3542   return true;
3543 }
3544 
3545 //------------------------------reorg_offsets----------------------------------
3546 // Reorganize offset computations to lower register pressure.  Mostly
3547 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3548 // then alive with the post-incremented trip counter forcing an extra
3549 // register move)
3550 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3551   // Perform it only for canonical counted loops.
3552   // Loop's shape could be messed up by iteration_split_impl.
3553   if (!loop->_head->is_CountedLoop())
3554     return;
3555   if (!loop->_head->as_Loop()->is_valid_counted_loop())
3556     return;
3557 
3558   CountedLoopNode *cl = loop->_head->as_CountedLoop();
3559   CountedLoopEndNode *cle = cl->loopexit();
3560   Node *exit = cle->proj_out(false);
3561   Node *phi = cl->phi();
3562 
3563   // Check for the special case when using the pre-incremented trip-counter on
3564   // the fall-out  path (forces the pre-incremented  and post-incremented trip
3565   // counter to be live  at the same time).  Fix this by  adjusting to use the
3566   // post-increment trip counter.
3567 
3568   bool progress = true;
3569   while (progress) {
3570     progress = false;
3571     for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3572       Node* use = phi->fast_out(i);   // User of trip-counter
3573       if (!has_ctrl(use))  continue;
3574       Node *u_ctrl = get_ctrl(use);
3575       if (use->is_Phi()) {
3576         u_ctrl = NULL;
3577         for (uint j = 1; j < use->req(); j++)
3578           if (use->in(j) == phi)
3579             u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3580       }
3581       IdealLoopTree *u_loop = get_loop(u_ctrl);
3582       // Look for loop-invariant use
3583       if (u_loop == loop) continue;
3584       if (loop->is_member(u_loop)) continue;
3585       // Check that use is live out the bottom.  Assuming the trip-counter
3586       // update is right at the bottom, uses of of the loop middle are ok.
3587       if (dom_lca(exit, u_ctrl) != exit) continue;
3588       // Hit!  Refactor use to use the post-incremented tripcounter.
3589       // Compute a post-increment tripcounter.
3590       Node* c = exit;
3591       if (cl->is_strip_mined()) {
3592         IdealLoopTree* outer_loop = get_loop(cl->outer_loop());
3593         if (!outer_loop->is_member(u_loop)) {
3594           c = cl->outer_loop_exit();
3595         }
3596       }
3597       Node *opaq = new Opaque2Node(C, cle->incr());
3598       register_new_node(opaq, c);
3599       Node *neg_stride = _igvn.intcon(-cle->stride_con());
3600       set_ctrl(neg_stride, C->root());
3601       Node *post = new AddINode(opaq, neg_stride);
3602       register_new_node(post, c);
3603       _igvn.rehash_node_delayed(use);
3604       for (uint j = 1; j < use->req(); j++) {
3605         if (use->in(j) == phi)
3606           use->set_req(j, post);
3607       }
3608       // Since DU info changed, rerun loop
3609       progress = true;
3610       break;
3611     }
3612   }
3613 
3614 }