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/subtypenode.hpp"
  44 #include "utilities/macros.hpp"
  45 
  46 //=============================================================================
  47 //------------------------------split_thru_phi---------------------------------
  48 // Split Node 'n' through merge point if there is enough win.
  49 Node* PhaseIdealLoop::split_thru_phi(Node* n, Node* region, int policy) {
  50   if (n->Opcode() == Op_ConvI2L && n->bottom_type() != TypeLong::LONG) {
  51     // ConvI2L may have type information on it which is unsafe to push up
  52     // so disable this for now
  53     return NULL;
  54   }
  55 
  56   // Splitting range check CastIIs through a loop induction Phi can
  57   // cause new Phis to be created that are left unrelated to the loop
  58   // induction Phi and prevent optimizations (vectorization)
  59   if (n->Opcode() == Op_CastII && n->as_CastII()->has_range_check() &&
  60       region->is_CountedLoop() && n->in(1) == region->as_CountedLoop()->phi()) {
  61     return NULL;
  62   }
  63 
  64   // Bail out if 'n' is a Div or Mod node whose zero check was removed earlier (i.e. control is NULL) and its divisor is an induction variable
  65   // phi p of a trip-counted (integer) loop whose inputs could be zero (include zero in their type range). p could have a more precise type
  66   // range that does not necessarily include all values of its inputs. Since each of these inputs will be a divisor of the newly cloned nodes
  67   // of 'n', we need to bail out of one of these divisors could be zero (zero in its type range).
  68   if ((n->Opcode() == Op_DivI || n->Opcode() == Op_ModI) && n->in(0) == NULL
  69       && region->is_CountedLoop() && n->in(2) == region->as_CountedLoop()->phi()) {
  70     Node* phi = region->as_CountedLoop()->phi();
  71     for (uint i = 1; i < phi->req(); i++) {
  72       if (_igvn.type(phi->in(i))->filter_speculative(TypeInt::ZERO) != Type::TOP) {
  73         // Zero could be a possible value but we already removed the zero check. Bail out to avoid a possible division by zero at a later point.
  74         return NULL;
  75       }
  76     }
  77   }
  78 
  79   int wins = 0;
  80   assert(!n->is_CFG(), "");
  81   assert(region->is_Region(), "");
  82 
  83   const Type* type = n->bottom_type();
  84   const TypeOopPtr* t_oop = _igvn.type(n)->isa_oopptr();
  85   Node* phi;
  86   if (t_oop != NULL && t_oop->is_known_instance_field()) {
  87     int iid    = t_oop->instance_id();
  88     int index  = C->get_alias_index(t_oop);
  89     int offset = t_oop->offset();
  90     phi = new PhiNode(region, type, NULL, iid, index, offset);
  91   } else {
  92     phi = PhiNode::make_blank(region, n);
  93   }
  94   uint old_unique = C->unique();
  95   for (uint i = 1; i < region->req(); i++) {
  96     Node* x;
  97     Node* the_clone = NULL;
  98     if (region->in(i) == C->top()) {
  99       x = C->top();             // Dead path?  Use a dead data op
 100     } else {
 101       x = n->clone();           // Else clone up the data op
 102       the_clone = x;            // Remember for possible deletion.
 103       // Alter data node to use pre-phi inputs
 104       if (n->in(0) == region)
 105         x->set_req( 0, region->in(i) );
 106       for (uint j = 1; j < n->req(); j++) {
 107         Node* in = n->in(j);
 108         if (in->is_Phi() && in->in(0) == region)
 109           x->set_req(j, in->in(i)); // Use pre-Phi input for the clone
 110       }
 111     }
 112     // Check for a 'win' on some paths
 113     const Type* t = x->Value(&_igvn);
 114 
 115     bool singleton = t->singleton();
 116 
 117     // A TOP singleton indicates that there are no possible values incoming
 118     // along a particular edge. In most cases, this is OK, and the Phi will
 119     // be eliminated later in an Ideal call. However, we can't allow this to
 120     // happen if the singleton occurs on loop entry, as the elimination of
 121     // the PhiNode may cause the resulting node to migrate back to a previous
 122     // loop iteration.
 123     if (singleton && t == Type::TOP) {
 124       // Is_Loop() == false does not confirm the absence of a loop (e.g., an
 125       // irreducible loop may not be indicated by an affirmative is_Loop());
 126       // therefore, the only top we can split thru a phi is on a backedge of
 127       // a loop.
 128       singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
 129     }
 130 
 131     if (singleton) {
 132       wins++;
 133       x = ((PhaseGVN&)_igvn).makecon(t);
 134     } else {
 135       // We now call Identity to try to simplify the cloned node.
 136       // Note that some Identity methods call phase->type(this).
 137       // Make sure that the type array is big enough for
 138       // our new node, even though we may throw the node away.
 139       // (Note: This tweaking with igvn only works because x is a new node.)
 140       _igvn.set_type(x, t);
 141       // If x is a TypeNode, capture any more-precise type permanently into Node
 142       // otherwise it will be not updated during igvn->transform since
 143       // igvn->type(x) is set to x->Value() already.
 144       x->raise_bottom_type(t);
 145       Node* y = x->Identity(&_igvn);
 146       if (y != x) {
 147         wins++;
 148         x = y;
 149       } else {
 150         y = _igvn.hash_find(x);
 151         if (y) {
 152           wins++;
 153           x = y;
 154         } else {
 155           // Else x is a new node we are keeping
 156           // We do not need register_new_node_with_optimizer
 157           // because set_type has already been called.
 158           _igvn._worklist.push(x);
 159         }
 160       }
 161     }
 162     if (x != the_clone && the_clone != NULL)
 163       _igvn.remove_dead_node(the_clone);
 164     phi->set_req( i, x );
 165   }
 166   // Too few wins?
 167   if (wins <= policy) {
 168     _igvn.remove_dead_node(phi);
 169     return NULL;
 170   }
 171 
 172   // Record Phi
 173   register_new_node( phi, region );
 174 
 175   for (uint i2 = 1; i2 < phi->req(); i2++) {
 176     Node *x = phi->in(i2);
 177     // If we commoned up the cloned 'x' with another existing Node,
 178     // the existing Node picks up a new use.  We need to make the
 179     // existing Node occur higher up so it dominates its uses.
 180     Node *old_ctrl;
 181     IdealLoopTree *old_loop;
 182 
 183     if (x->is_Con()) {
 184       // Constant's control is always root.
 185       set_ctrl(x, C->root());
 186       continue;
 187     }
 188     // The occasional new node
 189     if (x->_idx >= old_unique) {     // Found a new, unplaced node?
 190       old_ctrl = NULL;
 191       old_loop = NULL;               // Not in any prior loop
 192     } else {
 193       old_ctrl = get_ctrl(x);
 194       old_loop = get_loop(old_ctrl); // Get prior loop
 195     }
 196     // New late point must dominate new use
 197     Node *new_ctrl = dom_lca(old_ctrl, region->in(i2));
 198     if (new_ctrl == old_ctrl) // Nothing is changed
 199       continue;
 200 
 201     IdealLoopTree *new_loop = get_loop(new_ctrl);
 202 
 203     // Don't move x into a loop if its uses are
 204     // outside of loop. Otherwise x will be cloned
 205     // for each use outside of this loop.
 206     IdealLoopTree *use_loop = get_loop(region);
 207     if (!new_loop->is_member(use_loop) &&
 208         (old_loop == NULL || !new_loop->is_member(old_loop))) {
 209       // Take early control, later control will be recalculated
 210       // during next iteration of loop optimizations.
 211       new_ctrl = get_early_ctrl(x);
 212       new_loop = get_loop(new_ctrl);
 213     }
 214     // Set new location
 215     set_ctrl(x, new_ctrl);
 216     // If changing loop bodies, see if we need to collect into new body
 217     if (old_loop != new_loop) {
 218       if (old_loop && !old_loop->_child)
 219         old_loop->_body.yank(x);
 220       if (!new_loop->_child)
 221         new_loop->_body.push(x);  // Collect body info
 222     }
 223   }
 224 
 225   return phi;
 226 }
 227 
 228 //------------------------------dominated_by------------------------------------
 229 // Replace the dominated test with an obvious true or false.  Place it on the
 230 // IGVN worklist for later cleanup.  Move control-dependent data Nodes on the
 231 // live path up to the dominating control.
 232 void PhaseIdealLoop::dominated_by( Node *prevdom, Node *iff, bool flip, bool exclude_loop_predicate ) {
 233   if (VerifyLoopOptimizations && PrintOpto) { tty->print_cr("dominating test"); }
 234 
 235   // prevdom is the dominating projection of the dominating test.
 236   assert( iff->is_If(), "" );
 237   assert(iff->Opcode() == Op_If || iff->Opcode() == Op_CountedLoopEnd || iff->Opcode() == Op_RangeCheck, "Check this code when new subtype is added");
 238   int pop = prevdom->Opcode();
 239   assert( pop == Op_IfFalse || pop == Op_IfTrue, "" );
 240   if (flip) {
 241     if (pop == Op_IfTrue)
 242       pop = Op_IfFalse;
 243     else
 244       pop = Op_IfTrue;
 245   }
 246   // 'con' is set to true or false to kill the dominated test.
 247   Node *con = _igvn.makecon(pop == Op_IfTrue ? TypeInt::ONE : TypeInt::ZERO);
 248   set_ctrl(con, C->root()); // Constant gets a new use
 249   // Hack the dominated test
 250   _igvn.replace_input_of(iff, 1, con);
 251 
 252   // If I dont have a reachable TRUE and FALSE path following the IfNode then
 253   // I can assume this path reaches an infinite loop.  In this case it's not
 254   // important to optimize the data Nodes - either the whole compilation will
 255   // be tossed or this path (and all data Nodes) will go dead.
 256   if (iff->outcnt() != 2) return;
 257 
 258   // Make control-dependent data Nodes on the live path (path that will remain
 259   // once the dominated IF is removed) become control-dependent on the
 260   // dominating projection.
 261   Node* dp = iff->as_If()->proj_out_or_null(pop == Op_IfTrue);
 262 
 263   // Loop predicates may have depending checks which should not
 264   // be skipped. For example, range check predicate has two checks
 265   // for lower and upper bounds.
 266   if (dp == NULL)
 267     return;
 268 
 269   ProjNode* dp_proj  = dp->as_Proj();
 270   ProjNode* unc_proj = iff->as_If()->proj_out(1 - dp_proj->_con)->as_Proj();
 271   if (exclude_loop_predicate &&
 272       (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL ||
 273        unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_profile_predicate) != NULL ||
 274        unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check) != NULL)) {
 275     // If this is a range check (IfNode::is_range_check), do not
 276     // reorder because Compile::allow_range_check_smearing might have
 277     // changed the check.
 278     return; // Let IGVN transformation change control dependence.
 279   }
 280 
 281   IdealLoopTree *old_loop = get_loop(dp);
 282 
 283   for (DUIterator_Fast imax, i = dp->fast_outs(imax); i < imax; i++) {
 284     Node* cd = dp->fast_out(i); // Control-dependent node
 285     if (cd->depends_only_on_test()) {
 286       assert(cd->in(0) == dp, "");
 287       _igvn.replace_input_of(cd, 0, prevdom);
 288       set_early_ctrl(cd);
 289       IdealLoopTree *new_loop = get_loop(get_ctrl(cd));
 290       if (old_loop != new_loop) {
 291         if (!old_loop->_child) old_loop->_body.yank(cd);
 292         if (!new_loop->_child) new_loop->_body.push(cd);
 293       }
 294       --i;
 295       --imax;
 296     }
 297   }
 298 }
 299 
 300 //------------------------------has_local_phi_input----------------------------
 301 // Return TRUE if 'n' has Phi inputs from its local block and no other
 302 // block-local inputs (all non-local-phi inputs come from earlier blocks)
 303 Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
 304   Node *n_ctrl = get_ctrl(n);
 305   // See if some inputs come from a Phi in this block, or from before
 306   // this block.
 307   uint i;
 308   for( i = 1; i < n->req(); i++ ) {
 309     Node *phi = n->in(i);
 310     if( phi->is_Phi() && phi->in(0) == n_ctrl )
 311       break;
 312   }
 313   if( i >= n->req() )
 314     return NULL;                // No Phi inputs; nowhere to clone thru
 315 
 316   // Check for inputs created between 'n' and the Phi input.  These
 317   // must split as well; they have already been given the chance
 318   // (courtesy of a post-order visit) and since they did not we must
 319   // recover the 'cost' of splitting them by being very profitable
 320   // when splitting 'n'.  Since this is unlikely we simply give up.
 321   for( i = 1; i < n->req(); i++ ) {
 322     Node *m = n->in(i);
 323     if( get_ctrl(m) == n_ctrl && !m->is_Phi() ) {
 324       // We allow the special case of AddP's with no local inputs.
 325       // This allows us to split-up address expressions.
 326       if (m->is_AddP() &&
 327           get_ctrl(m->in(2)) != n_ctrl &&
 328           get_ctrl(m->in(3)) != n_ctrl) {
 329         // Move the AddP up to dominating point
 330         Node* c = find_non_split_ctrl(idom(n_ctrl));
 331         if (c->is_OuterStripMinedLoop()) {
 332           c->as_Loop()->verify_strip_mined(1);
 333           c = c->in(LoopNode::EntryControl);
 334         }
 335         set_ctrl_and_loop(m, c);
 336         continue;
 337       }
 338       return NULL;
 339     }
 340     assert(n->is_Phi() || m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
 341   }
 342 
 343   return n_ctrl;
 344 }
 345 
 346 //------------------------------remix_address_expressions----------------------
 347 // Rework addressing expressions to get the most loop-invariant stuff
 348 // moved out.  We'd like to do all associative operators, but it's especially
 349 // important (common) to do address expressions.
 350 Node *PhaseIdealLoop::remix_address_expressions( Node *n ) {
 351   if (!has_ctrl(n))  return NULL;
 352   Node *n_ctrl = get_ctrl(n);
 353   IdealLoopTree *n_loop = get_loop(n_ctrl);
 354 
 355   // See if 'n' mixes loop-varying and loop-invariant inputs and
 356   // itself is loop-varying.
 357 
 358   // Only interested in binary ops (and AddP)
 359   if( n->req() < 3 || n->req() > 4 ) return NULL;
 360 
 361   Node *n1_ctrl = get_ctrl(n->in(                    1));
 362   Node *n2_ctrl = get_ctrl(n->in(                    2));
 363   Node *n3_ctrl = get_ctrl(n->in(n->req() == 3 ? 2 : 3));
 364   IdealLoopTree *n1_loop = get_loop( n1_ctrl );
 365   IdealLoopTree *n2_loop = get_loop( n2_ctrl );
 366   IdealLoopTree *n3_loop = get_loop( n3_ctrl );
 367 
 368   // Does one of my inputs spin in a tighter loop than self?
 369   if( (n_loop->is_member( n1_loop ) && n_loop != n1_loop) ||
 370       (n_loop->is_member( n2_loop ) && n_loop != n2_loop) ||
 371       (n_loop->is_member( n3_loop ) && n_loop != n3_loop) )
 372     return NULL;                // Leave well enough alone
 373 
 374   // Is at least one of my inputs loop-invariant?
 375   if( n1_loop == n_loop &&
 376       n2_loop == n_loop &&
 377       n3_loop == n_loop )
 378     return NULL;                // No loop-invariant inputs
 379 
 380 
 381   int n_op = n->Opcode();
 382 
 383   // Replace expressions like ((V+I) << 2) with (V<<2 + I<<2).
 384   if( n_op == Op_LShiftI ) {
 385     // Scale is loop invariant
 386     Node *scale = n->in(2);
 387     Node *scale_ctrl = get_ctrl(scale);
 388     IdealLoopTree *scale_loop = get_loop(scale_ctrl );
 389     if( n_loop == scale_loop || !scale_loop->is_member( n_loop ) )
 390       return NULL;
 391     const TypeInt *scale_t = scale->bottom_type()->isa_int();
 392     if( scale_t && scale_t->is_con() && scale_t->get_con() >= 16 )
 393       return NULL;              // Dont bother with byte/short masking
 394     // Add must vary with loop (else shift would be loop-invariant)
 395     Node *add = n->in(1);
 396     Node *add_ctrl = get_ctrl(add);
 397     IdealLoopTree *add_loop = get_loop(add_ctrl);
 398     //assert( n_loop == add_loop, "" );
 399     if( n_loop != add_loop ) return NULL;  // happens w/ evil ZKM loops
 400 
 401     // Convert I-V into I+ (0-V); same for V-I
 402     if( add->Opcode() == Op_SubI &&
 403         _igvn.type( add->in(1) ) != TypeInt::ZERO ) {
 404       Node *zero = _igvn.intcon(0);
 405       set_ctrl(zero, C->root());
 406       Node *neg = new SubINode( _igvn.intcon(0), add->in(2) );
 407       register_new_node( neg, get_ctrl(add->in(2) ) );
 408       add = new AddINode( add->in(1), neg );
 409       register_new_node( add, add_ctrl );
 410     }
 411     if( add->Opcode() != Op_AddI ) return NULL;
 412     // See if one add input is loop invariant
 413     Node *add_var = add->in(1);
 414     Node *add_var_ctrl = get_ctrl(add_var);
 415     IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
 416     Node *add_invar = add->in(2);
 417     Node *add_invar_ctrl = get_ctrl(add_invar);
 418     IdealLoopTree *add_invar_loop = get_loop(add_invar_ctrl );
 419     if( add_var_loop == n_loop ) {
 420     } else if( add_invar_loop == n_loop ) {
 421       // Swap to find the invariant part
 422       add_invar = add_var;
 423       add_invar_ctrl = add_var_ctrl;
 424       add_invar_loop = add_var_loop;
 425       add_var = add->in(2);
 426       Node *add_var_ctrl = get_ctrl(add_var);
 427       IdealLoopTree *add_var_loop = get_loop(add_var_ctrl );
 428     } else                      // Else neither input is loop invariant
 429       return NULL;
 430     if( n_loop == add_invar_loop || !add_invar_loop->is_member( n_loop ) )
 431       return NULL;              // No invariant part of the add?
 432 
 433     // Yes!  Reshape address expression!
 434     Node *inv_scale = new LShiftINode( add_invar, scale );
 435     Node *inv_scale_ctrl =
 436       dom_depth(add_invar_ctrl) > dom_depth(scale_ctrl) ?
 437       add_invar_ctrl : scale_ctrl;
 438     register_new_node( inv_scale, inv_scale_ctrl );
 439     Node *var_scale = new LShiftINode( add_var, scale );
 440     register_new_node( var_scale, n_ctrl );
 441     Node *var_add = new AddINode( var_scale, inv_scale );
 442     register_new_node( var_add, n_ctrl );
 443     _igvn.replace_node( n, var_add );
 444     return var_add;
 445   }
 446 
 447   // Replace (I+V) with (V+I)
 448   if( n_op == Op_AddI ||
 449       n_op == Op_AddL ||
 450       n_op == Op_AddF ||
 451       n_op == Op_AddD ||
 452       n_op == Op_MulI ||
 453       n_op == Op_MulL ||
 454       n_op == Op_MulF ||
 455       n_op == Op_MulD ) {
 456     if( n2_loop == n_loop ) {
 457       assert( n1_loop != n_loop, "" );
 458       n->swap_edges(1, 2);
 459     }
 460   }
 461 
 462   // Replace ((I1 +p V) +p I2) with ((I1 +p I2) +p V),
 463   // but not if I2 is a constant.
 464   if( n_op == Op_AddP ) {
 465     if( n2_loop == n_loop && n3_loop != n_loop ) {
 466       if( n->in(2)->Opcode() == Op_AddP && !n->in(3)->is_Con() ) {
 467         Node *n22_ctrl = get_ctrl(n->in(2)->in(2));
 468         Node *n23_ctrl = get_ctrl(n->in(2)->in(3));
 469         IdealLoopTree *n22loop = get_loop( n22_ctrl );
 470         IdealLoopTree *n23_loop = get_loop( n23_ctrl );
 471         if( n22loop != n_loop && n22loop->is_member(n_loop) &&
 472             n23_loop == n_loop ) {
 473           Node *add1 = new AddPNode( n->in(1), n->in(2)->in(2), n->in(3) );
 474           // Stuff new AddP in the loop preheader
 475           register_new_node( add1, n_loop->_head->in(LoopNode::EntryControl) );
 476           Node *add2 = new AddPNode( n->in(1), add1, n->in(2)->in(3) );
 477           register_new_node( add2, n_ctrl );
 478           _igvn.replace_node( n, add2 );
 479           return add2;
 480         }
 481       }
 482     }
 483 
 484     // Replace (I1 +p (I2 + V)) with ((I1 +p I2) +p V)
 485     if (n2_loop != n_loop && n3_loop == n_loop) {
 486       if (n->in(3)->Opcode() == Op_AddX) {
 487         Node *V = n->in(3)->in(1);
 488         Node *I = n->in(3)->in(2);
 489         if (is_member(n_loop,get_ctrl(V))) {
 490         } else {
 491           Node *tmp = V; V = I; I = tmp;
 492         }
 493         if (!is_member(n_loop,get_ctrl(I))) {
 494           Node *add1 = new AddPNode(n->in(1), n->in(2), I);
 495           // Stuff new AddP in the loop preheader
 496           register_new_node(add1, n_loop->_head->in(LoopNode::EntryControl));
 497           Node *add2 = new AddPNode(n->in(1), add1, V);
 498           register_new_node(add2, n_ctrl);
 499           _igvn.replace_node(n, add2);
 500           return add2;
 501         }
 502       }
 503     }
 504   }
 505 
 506   return NULL;
 507 }
 508 
 509 // Optimize ((in1[2*i] * in2[2*i]) + (in1[2*i+1] * in2[2*i+1]))
 510 Node *PhaseIdealLoop::convert_add_to_muladd(Node* n) {
 511   assert(n->Opcode() == Op_AddI, "sanity");
 512   Node * nn = NULL;
 513   Node * in1 = n->in(1);
 514   Node * in2 = n->in(2);
 515   if (in1->Opcode() == Op_MulI && in2->Opcode() == Op_MulI) {
 516     IdealLoopTree* loop_n = get_loop(get_ctrl(n));
 517     if (loop_n->is_counted() &&
 518         loop_n->_head->as_Loop()->is_valid_counted_loop() &&
 519         Matcher::match_rule_supported(Op_MulAddVS2VI) &&
 520         Matcher::match_rule_supported(Op_MulAddS2I)) {
 521       Node* mul_in1 = in1->in(1);
 522       Node* mul_in2 = in1->in(2);
 523       Node* mul_in3 = in2->in(1);
 524       Node* mul_in4 = in2->in(2);
 525       if (mul_in1->Opcode() == Op_LoadS &&
 526           mul_in2->Opcode() == Op_LoadS &&
 527           mul_in3->Opcode() == Op_LoadS &&
 528           mul_in4->Opcode() == Op_LoadS) {
 529         IdealLoopTree* loop1 = get_loop(get_ctrl(mul_in1));
 530         IdealLoopTree* loop2 = get_loop(get_ctrl(mul_in2));
 531         IdealLoopTree* loop3 = get_loop(get_ctrl(mul_in3));
 532         IdealLoopTree* loop4 = get_loop(get_ctrl(mul_in4));
 533         IdealLoopTree* loop5 = get_loop(get_ctrl(in1));
 534         IdealLoopTree* loop6 = get_loop(get_ctrl(in2));
 535         // All nodes should be in the same counted loop.
 536         if (loop_n == loop1 && loop_n == loop2 && loop_n == loop3 &&
 537             loop_n == loop4 && loop_n == loop5 && loop_n == loop6) {
 538           Node* adr1 = mul_in1->in(MemNode::Address);
 539           Node* adr2 = mul_in2->in(MemNode::Address);
 540           Node* adr3 = mul_in3->in(MemNode::Address);
 541           Node* adr4 = mul_in4->in(MemNode::Address);
 542           if (adr1->is_AddP() && adr2->is_AddP() && adr3->is_AddP() && adr4->is_AddP()) {
 543             if ((adr1->in(AddPNode::Base) == adr3->in(AddPNode::Base)) &&
 544                 (adr2->in(AddPNode::Base) == adr4->in(AddPNode::Base))) {
 545               nn = new MulAddS2INode(mul_in1, mul_in2, mul_in3, mul_in4);
 546               register_new_node(nn, get_ctrl(n));
 547               _igvn.replace_node(n, nn);
 548               return nn;
 549             } else if ((adr1->in(AddPNode::Base) == adr4->in(AddPNode::Base)) &&
 550                        (adr2->in(AddPNode::Base) == adr3->in(AddPNode::Base))) {
 551               nn = new MulAddS2INode(mul_in1, mul_in2, mul_in4, mul_in3);
 552               register_new_node(nn, get_ctrl(n));
 553               _igvn.replace_node(n, nn);
 554               return nn;
 555             }
 556           }
 557         }
 558       }
 559     }
 560   }
 561   return nn;
 562 }
 563 
 564 //------------------------------conditional_move-------------------------------
 565 // Attempt to replace a Phi with a conditional move.  We have some pretty
 566 // strict profitability requirements.  All Phis at the merge point must
 567 // be converted, so we can remove the control flow.  We need to limit the
 568 // number of c-moves to a small handful.  All code that was in the side-arms
 569 // of the CFG diamond is now speculatively executed.  This code has to be
 570 // "cheap enough".  We are pretty much limited to CFG diamonds that merge
 571 // 1 or 2 items with a total of 1 or 2 ops executed speculatively.
 572 Node *PhaseIdealLoop::conditional_move( Node *region ) {
 573 
 574   assert(region->is_Region(), "sanity check");
 575   if (region->req() != 3) return NULL;
 576 
 577   // Check for CFG diamond
 578   Node *lp = region->in(1);
 579   Node *rp = region->in(2);
 580   if (!lp || !rp) return NULL;
 581   Node *lp_c = lp->in(0);
 582   if (lp_c == NULL || lp_c != rp->in(0) || !lp_c->is_If()) return NULL;
 583   IfNode *iff = lp_c->as_If();
 584 
 585   // Check for ops pinned in an arm of the diamond.
 586   // Can't remove the control flow in this case
 587   if (lp->outcnt() > 1) return NULL;
 588   if (rp->outcnt() > 1) return NULL;
 589 
 590   IdealLoopTree* r_loop = get_loop(region);
 591   assert(r_loop == get_loop(iff), "sanity");
 592   // Always convert to CMOVE if all results are used only outside this loop.
 593   bool used_inside_loop = (r_loop == _ltree_root);
 594 
 595   // Check profitability
 596   int cost = 0;
 597   int phis = 0;
 598   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 599     Node *out = region->fast_out(i);
 600     if (!out->is_Phi()) continue; // Ignore other control edges, etc
 601     phis++;
 602     PhiNode* phi = out->as_Phi();
 603     BasicType bt = phi->type()->basic_type();
 604     switch (bt) {
 605     case T_DOUBLE:
 606     case T_FLOAT:
 607       if (C->use_cmove()) {
 608         continue; //TODO: maybe we want to add some cost
 609       }
 610       cost += Matcher::float_cmove_cost(); // Could be very expensive
 611       break;
 612     case T_LONG: {
 613       cost += Matcher::long_cmove_cost(); // May encodes as 2 CMOV's
 614     }
 615     case T_INT:                 // These all CMOV fine
 616     case T_ADDRESS: {           // (RawPtr)
 617       cost++;
 618       break;
 619     }
 620     case T_NARROWOOP: // Fall through
 621     case T_OBJECT: {            // Base oops are OK, but not derived oops
 622       const TypeOopPtr *tp = phi->type()->make_ptr()->isa_oopptr();
 623       // Derived pointers are Bad (tm): what's the Base (for GC purposes) of a
 624       // CMOVE'd derived pointer?  It's a CMOVE'd derived base.  Thus
 625       // CMOVE'ing a derived pointer requires we also CMOVE the base.  If we
 626       // have a Phi for the base here that we convert to a CMOVE all is well
 627       // and good.  But if the base is dead, we'll not make a CMOVE.  Later
 628       // the allocator will have to produce a base by creating a CMOVE of the
 629       // relevant bases.  This puts the allocator in the business of
 630       // manufacturing expensive instructions, generally a bad plan.
 631       // Just Say No to Conditionally-Moved Derived Pointers.
 632       if (tp && tp->offset() != 0)
 633         return NULL;
 634       cost++;
 635       break;
 636     }
 637     default:
 638       return NULL;              // In particular, can't do memory or I/O
 639     }
 640     // Add in cost any speculative ops
 641     for (uint j = 1; j < region->req(); j++) {
 642       Node *proj = region->in(j);
 643       Node *inp = phi->in(j);
 644       if (get_ctrl(inp) == proj) { // Found local op
 645         cost++;
 646         // Check for a chain of dependent ops; these will all become
 647         // speculative in a CMOV.
 648         for (uint k = 1; k < inp->req(); k++)
 649           if (get_ctrl(inp->in(k)) == proj)
 650             cost += ConditionalMoveLimit; // Too much speculative goo
 651       }
 652     }
 653     // See if the Phi is used by a Cmp or Narrow oop Decode/Encode.
 654     // This will likely Split-If, a higher-payoff operation.
 655     for (DUIterator_Fast kmax, k = phi->fast_outs(kmax); k < kmax; k++) {
 656       Node* use = phi->fast_out(k);
 657       if (use->is_Cmp() || use->is_DecodeNarrowPtr() || use->is_EncodeNarrowPtr())
 658         cost += ConditionalMoveLimit;
 659       // Is there a use inside the loop?
 660       // Note: check only basic types since CMoveP is pinned.
 661       if (!used_inside_loop && is_java_primitive(bt)) {
 662         IdealLoopTree* u_loop = get_loop(has_ctrl(use) ? get_ctrl(use) : use);
 663         if (r_loop == u_loop || r_loop->is_member(u_loop)) {
 664           used_inside_loop = true;
 665         }
 666       }
 667     }
 668   }//for
 669   Node* bol = iff->in(1);
 670   if (bol->Opcode() == Op_Opaque4) {
 671     return NULL; // Ignore loop predicate checks (the Opaque4 ensures they will go away)
 672   }
 673   assert(bol->Opcode() == Op_Bool, "Unexpected node");
 674   int cmp_op = bol->in(1)->Opcode();
 675   if (cmp_op == Op_SubTypeCheck) { // SubTypeCheck expansion expects an IfNode
 676     return NULL;
 677   }
 678   // It is expensive to generate flags from a float compare.
 679   // Avoid duplicated float compare.
 680   if (phis > 1 && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) return NULL;
 681 
 682   float infrequent_prob = PROB_UNLIKELY_MAG(3);
 683   // Ignore cost and blocks frequency if CMOVE can be moved outside the loop.
 684   if (used_inside_loop) {
 685     if (cost >= ConditionalMoveLimit) return NULL; // Too much goo
 686 
 687     // BlockLayoutByFrequency optimization moves infrequent branch
 688     // from hot path. No point in CMOV'ing in such case (110 is used
 689     // instead of 100 to take into account not exactness of float value).
 690     if (BlockLayoutByFrequency) {
 691       infrequent_prob = MAX2(infrequent_prob, (float)BlockLayoutMinDiamondPercentage/110.0f);
 692     }
 693   }
 694   // Check for highly predictable branch.  No point in CMOV'ing if
 695   // we are going to predict accurately all the time.
 696   if (C->use_cmove() && (cmp_op == Op_CmpF || cmp_op == Op_CmpD)) {
 697     //keep going
 698   } else if (iff->_prob < infrequent_prob ||
 699       iff->_prob > (1.0f - infrequent_prob))
 700     return NULL;
 701 
 702   // --------------
 703   // Now replace all Phis with CMOV's
 704   Node *cmov_ctrl = iff->in(0);
 705   uint flip = (lp->Opcode() == Op_IfTrue);
 706   Node_List wq;
 707   while (1) {
 708     PhiNode* phi = NULL;
 709     for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
 710       Node *out = region->fast_out(i);
 711       if (out->is_Phi()) {
 712         phi = out->as_Phi();
 713         break;
 714       }
 715     }
 716     if (phi == NULL)  break;
 717     if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
 718     // Move speculative ops
 719     wq.push(phi);
 720     while (wq.size() > 0) {
 721       Node *n = wq.pop();
 722       for (uint j = 1; j < n->req(); j++) {
 723         Node* m = n->in(j);
 724         if (m != NULL && !is_dominator(get_ctrl(m), cmov_ctrl)) {
 725 #ifndef PRODUCT
 726           if (PrintOpto && VerifyLoopOptimizations) {
 727             tty->print("  speculate: ");
 728             m->dump();
 729           }
 730 #endif
 731           set_ctrl(m, cmov_ctrl);
 732           wq.push(m);
 733         }
 734       }
 735     }
 736     Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));
 737     register_new_node( cmov, cmov_ctrl );
 738     _igvn.replace_node( phi, cmov );
 739 #ifndef PRODUCT
 740     if (TraceLoopOpts) {
 741       tty->print("CMOV  ");
 742       r_loop->dump_head();
 743       if (Verbose) {
 744         bol->in(1)->dump(1);
 745         cmov->dump(1);
 746       }
 747     }
 748     if (VerifyLoopOptimizations) verify();
 749 #endif
 750   }
 751 
 752   // The useless CFG diamond will fold up later; see the optimization in
 753   // RegionNode::Ideal.
 754   _igvn._worklist.push(region);
 755 
 756   return iff->in(1);
 757 }
 758 
 759 static void enqueue_cfg_uses(Node* m, Unique_Node_List& wq) {
 760   for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
 761     Node* u = m->fast_out(i);
 762     if (u->is_CFG()) {
 763       if (u->Opcode() == Op_NeverBranch) {
 764         u = ((NeverBranchNode*)u)->proj_out(0);
 765         enqueue_cfg_uses(u, wq);
 766       } else {
 767         wq.push(u);
 768       }
 769     }
 770   }
 771 }
 772 
 773 // Try moving a store out of a loop, right before the loop
 774 Node* PhaseIdealLoop::try_move_store_before_loop(Node* n, Node *n_ctrl) {
 775   // Store has to be first in the loop body
 776   IdealLoopTree *n_loop = get_loop(n_ctrl);
 777   if (n->is_Store() && n_loop != _ltree_root &&
 778       n_loop->is_loop() && n_loop->_head->is_Loop() &&
 779       n->in(0) != NULL) {
 780     Node* address = n->in(MemNode::Address);
 781     Node* value = n->in(MemNode::ValueIn);
 782     Node* mem = n->in(MemNode::Memory);
 783     IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 784     IdealLoopTree* value_loop = get_loop(get_ctrl(value));
 785 
 786     // - address and value must be loop invariant
 787     // - memory must be a memory Phi for the loop
 788     // - Store must be the only store on this memory slice in the
 789     // loop: if there's another store following this one then value
 790     // written at iteration i by the second store could be overwritten
 791     // at iteration i+n by the first store: it's not safe to move the
 792     // first store out of the loop
 793     // - nothing must observe the memory Phi: it guarantees no read
 794     // before the store, we are also guaranteed the store post
 795     // dominates the loop head (ignoring a possible early
 796     // exit). Otherwise there would be extra Phi involved between the
 797     // loop's Phi and the store.
 798     // - there must be no early exit from the loop before the Store
 799     // (such an exit most of the time would be an extra use of the
 800     // memory Phi but sometimes is a bottom memory Phi that takes the
 801     // store as input).
 802 
 803     if (!n_loop->is_member(address_loop) &&
 804         !n_loop->is_member(value_loop) &&
 805         mem->is_Phi() && mem->in(0) == n_loop->_head &&
 806         mem->outcnt() == 1 &&
 807         mem->in(LoopNode::LoopBackControl) == n) {
 808 
 809       assert(n_loop->_tail != NULL, "need a tail");
 810       assert(is_dominator(n_ctrl, n_loop->_tail), "store control must not be in a branch in the loop");
 811 
 812       // Verify that there's no early exit of the loop before the store.
 813       bool ctrl_ok = false;
 814       {
 815         // Follow control from loop head until n, we exit the loop or
 816         // we reach the tail
 817         ResourceMark rm;
 818         Unique_Node_List wq;
 819         wq.push(n_loop->_head);
 820 
 821         for (uint next = 0; next < wq.size(); ++next) {
 822           Node *m = wq.at(next);
 823           if (m == n->in(0)) {
 824             ctrl_ok = true;
 825             continue;
 826           }
 827           assert(!has_ctrl(m), "should be CFG");
 828           if (!n_loop->is_member(get_loop(m)) || m == n_loop->_tail) {
 829             ctrl_ok = false;
 830             break;
 831           }
 832           enqueue_cfg_uses(m, wq);
 833           if (wq.size() > 10) {
 834             ctrl_ok = false;
 835             break;
 836           }
 837         }
 838       }
 839       if (ctrl_ok) {
 840         // move the Store
 841         _igvn.replace_input_of(mem, LoopNode::LoopBackControl, mem);
 842         _igvn.replace_input_of(n, 0, n_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl));
 843         _igvn.replace_input_of(n, MemNode::Memory, mem->in(LoopNode::EntryControl));
 844         // Disconnect the phi now. An empty phi can confuse other
 845         // optimizations in this pass of loop opts.
 846         _igvn.replace_node(mem, mem->in(LoopNode::EntryControl));
 847         n_loop->_body.yank(mem);
 848 
 849         set_ctrl_and_loop(n, n->in(0));
 850 
 851         return n;
 852       }
 853     }
 854   }
 855   return NULL;
 856 }
 857 
 858 // Try moving a store out of a loop, right after the loop
 859 void PhaseIdealLoop::try_move_store_after_loop(Node* n) {
 860   if (n->is_Store() && n->in(0) != NULL) {
 861     Node *n_ctrl = get_ctrl(n);
 862     IdealLoopTree *n_loop = get_loop(n_ctrl);
 863     // Store must be in a loop
 864     if (n_loop != _ltree_root && !n_loop->_irreducible) {
 865       Node* address = n->in(MemNode::Address);
 866       Node* value = n->in(MemNode::ValueIn);
 867       IdealLoopTree* address_loop = get_loop(get_ctrl(address));
 868       // address must be loop invariant
 869       if (!n_loop->is_member(address_loop)) {
 870         // Store must be last on this memory slice in the loop and
 871         // nothing in the loop must observe it
 872         Node* phi = NULL;
 873         for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 874           Node* u = n->fast_out(i);
 875           if (has_ctrl(u)) { // control use?
 876             IdealLoopTree *u_loop = get_loop(get_ctrl(u));
 877             if (!n_loop->is_member(u_loop)) {
 878               continue;
 879             }
 880             if (u->is_Phi() && u->in(0) == n_loop->_head) {
 881               assert(_igvn.type(u) == Type::MEMORY, "bad phi");
 882               // multiple phis on the same slice are possible
 883               if (phi != NULL) {
 884                 return;
 885               }
 886               phi = u;
 887               continue;
 888             }
 889           }
 890           return;
 891         }
 892         if (phi != NULL) {
 893           // Nothing in the loop before the store (next iteration)
 894           // must observe the stored value
 895           bool mem_ok = true;
 896           {
 897             ResourceMark rm;
 898             Unique_Node_List wq;
 899             wq.push(phi);
 900             for (uint next = 0; next < wq.size() && mem_ok; ++next) {
 901               Node *m = wq.at(next);
 902               for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax && mem_ok; i++) {
 903                 Node* u = m->fast_out(i);
 904                 if (u->is_Store() || u->is_Phi()) {
 905                   if (u != n) {
 906                     wq.push(u);
 907                     mem_ok = (wq.size() <= 10);
 908                   }
 909                 } else {
 910                   mem_ok = false;
 911                   break;
 912                 }
 913               }
 914             }
 915           }
 916           if (mem_ok) {
 917             // Move the store out of the loop if the LCA of all
 918             // users (except for the phi) is outside the loop.
 919             Node* hook = new Node(1);
 920             hook->init_req(0, n_ctrl); // Add an input to prevent hook from being dead
 921             _igvn.rehash_node_delayed(phi);
 922             int count = phi->replace_edge(n, hook);
 923             assert(count > 0, "inconsistent phi");
 924 
 925             // Compute latest point this store can go
 926             Node* lca = get_late_ctrl(n, get_ctrl(n));
 927             if (lca->is_OuterStripMinedLoop()) {
 928               lca = lca->in(LoopNode::EntryControl);
 929             }
 930             if (n_loop->is_member(get_loop(lca))) {
 931               // LCA is in the loop - bail out
 932               _igvn.replace_node(hook, n);
 933               return;
 934             }
 935 #ifdef ASSERT
 936             if (n_loop->_head->is_Loop() && n_loop->_head->as_Loop()->is_strip_mined()) {
 937               assert(n_loop->_head->Opcode() == Op_CountedLoop, "outer loop is a strip mined");
 938               n_loop->_head->as_Loop()->verify_strip_mined(1);
 939               Node* outer = n_loop->_head->as_CountedLoop()->outer_loop();
 940               IdealLoopTree* outer_loop = get_loop(outer);
 941               assert(n_loop->_parent == outer_loop, "broken loop tree");
 942               assert(get_loop(lca) == outer_loop, "safepoint in outer loop consume all memory state");
 943             }
 944 #endif
 945 
 946             // Move store out of the loop
 947             _igvn.replace_node(hook, n->in(MemNode::Memory));
 948             _igvn.replace_input_of(n, 0, lca);
 949             set_ctrl_and_loop(n, lca);
 950 
 951             // Disconnect the phi now. An empty phi can confuse other
 952             // optimizations in this pass of loop opts..
 953             if (phi->in(LoopNode::LoopBackControl) == phi) {
 954               _igvn.replace_node(phi, phi->in(LoopNode::EntryControl));
 955               n_loop->_body.yank(phi);
 956             }
 957           }
 958         }
 959       }
 960     }
 961   }
 962 }
 963 
 964 //------------------------------split_if_with_blocks_pre-----------------------
 965 // Do the real work in a non-recursive function.  Data nodes want to be
 966 // cloned in the pre-order so they can feed each other nicely.
 967 Node *PhaseIdealLoop::split_if_with_blocks_pre( Node *n ) {
 968   // Cloning these guys is unlikely to win
 969   int n_op = n->Opcode();
 970   if (n_op == Op_MergeMem) {
 971     return n;
 972   }
 973   if (n->is_Proj()) {
 974     return n;
 975   }
 976   // Do not clone-up CmpFXXX variations, as these are always
 977   // followed by a CmpI
 978   if (n->is_Cmp()) {
 979     return n;
 980   }
 981   // Attempt to use a conditional move instead of a phi/branch
 982   if (ConditionalMoveLimit > 0 && n_op == Op_Region) {
 983     Node *cmov = conditional_move( n );
 984     if (cmov) {
 985       return cmov;
 986     }
 987   }
 988   if (n->is_CFG() || n->is_LoadStore()) {
 989     return n;
 990   }
 991   if (n->is_Opaque1() ||     // Opaque nodes cannot be mod'd
 992       n_op == Op_Opaque2) {
 993     if (!C->major_progress()) {   // If chance of no more loop opts...
 994       _igvn._worklist.push(n);  // maybe we'll remove them
 995     }
 996     return n;
 997   }
 998 
 999   if (n->is_Con()) {
1000     return n;   // No cloning for Con nodes
1001   }
1002 
1003   Node *n_ctrl = get_ctrl(n);
1004   if (!n_ctrl) {
1005     return n;       // Dead node
1006   }
1007 
1008   Node* res = try_move_store_before_loop(n, n_ctrl);
1009   if (res != NULL) {
1010     return n;
1011   }
1012 
1013   // Attempt to remix address expressions for loop invariants
1014   Node *m = remix_address_expressions( n );
1015   if( m ) return m;
1016 
1017   if (n_op == Op_AddI) {
1018     Node *nn = convert_add_to_muladd( n );
1019     if ( nn ) return nn;
1020   }
1021 
1022   if (n->is_ConstraintCast()) {
1023     Node* dom_cast = n->as_ConstraintCast()->dominating_cast(&_igvn, this);
1024     // ConstraintCastNode::dominating_cast() uses node control input to determine domination.
1025     // Node control inputs don't necessarily agree with loop control info (due to
1026     // transformations happened in between), thus additional dominance check is needed
1027     // to keep loop info valid.
1028     if (dom_cast != NULL && is_dominator(get_ctrl(dom_cast), get_ctrl(n))) {
1029       _igvn.replace_node(n, dom_cast);
1030       return dom_cast;
1031     }
1032   }
1033 
1034   // Determine if the Node has inputs from some local Phi.
1035   // Returns the block to clone thru.
1036   Node *n_blk = has_local_phi_input( n );
1037   if( !n_blk ) return n;
1038 
1039   // Do not clone the trip counter through on a CountedLoop
1040   // (messes up the canonical shape).
1041   if( n_blk->is_CountedLoop() && n->Opcode() == Op_AddI ) return n;
1042 
1043   // Check for having no control input; not pinned.  Allow
1044   // dominating control.
1045   if (n->in(0)) {
1046     Node *dom = idom(n_blk);
1047     if (dom_lca(n->in(0), dom) != n->in(0)) {
1048       return n;
1049     }
1050   }
1051   // Policy: when is it profitable.  You must get more wins than
1052   // policy before it is considered profitable.  Policy is usually 0,
1053   // so 1 win is considered profitable.  Big merges will require big
1054   // cloning, so get a larger policy.
1055   int policy = n_blk->req() >> 2;
1056 
1057   // If the loop is a candidate for range check elimination,
1058   // delay splitting through it's phi until a later loop optimization
1059   if (n_blk->is_CountedLoop()) {
1060     IdealLoopTree *lp = get_loop(n_blk);
1061     if (lp && lp->_rce_candidate) {
1062       return n;
1063     }
1064   }
1065 
1066   if (must_throttle_split_if()) return n;
1067 
1068   // Split 'n' through the merge point if it is profitable
1069   Node *phi = split_thru_phi( n, n_blk, policy );
1070   if (!phi) return n;
1071 
1072   // Found a Phi to split thru!
1073   // Replace 'n' with the new phi
1074   _igvn.replace_node( n, phi );
1075   // Moved a load around the loop, 'en-registering' something.
1076   if (n_blk->is_Loop() && n->is_Load() &&
1077       !phi->in(LoopNode::LoopBackControl)->is_Load())
1078     C->set_major_progress();
1079 
1080   return phi;
1081 }
1082 
1083 static bool merge_point_too_heavy(Compile* C, Node* region) {
1084   // Bail out if the region and its phis have too many users.
1085   int weight = 0;
1086   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1087     weight += region->fast_out(i)->outcnt();
1088   }
1089   int nodes_left = C->max_node_limit() - C->live_nodes();
1090   if (weight * 8 > nodes_left) {
1091     if (PrintOpto) {
1092       tty->print_cr("*** Split-if bails out:  %d nodes, region weight %d", C->unique(), weight);
1093     }
1094     return true;
1095   } else {
1096     return false;
1097   }
1098 }
1099 
1100 static bool merge_point_safe(Node* region) {
1101   // 4799512: Stop split_if_with_blocks from splitting a block with a ConvI2LNode
1102   // having a PhiNode input. This sidesteps the dangerous case where the split
1103   // ConvI2LNode may become TOP if the input Value() does not
1104   // overlap the ConvI2L range, leaving a node which may not dominate its
1105   // uses.
1106   // A better fix for this problem can be found in the BugTraq entry, but
1107   // expediency for Mantis demands this hack.
1108 #ifdef _LP64
1109   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1110     Node* n = region->fast_out(i);
1111     if (n->is_Phi()) {
1112       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1113         Node* m = n->fast_out(j);
1114         if (m->Opcode() == Op_ConvI2L)
1115           return false;
1116         if (m->is_CastII() && m->isa_CastII()->has_range_check()) {
1117           return false;
1118         }
1119       }
1120     }
1121   }
1122 #endif
1123   return true;
1124 }
1125 
1126 
1127 //------------------------------place_near_use---------------------------------
1128 // Place some computation next to use but not inside inner loops.
1129 // For inner loop uses move it to the preheader area.
1130 Node *PhaseIdealLoop::place_near_use(Node *useblock) const {
1131   IdealLoopTree *u_loop = get_loop( useblock );
1132   if (u_loop->_irreducible) {
1133     return useblock;
1134   }
1135   if (u_loop->_child) {
1136     if (useblock == u_loop->_head && u_loop->_head->is_OuterStripMinedLoop()) {
1137       return u_loop->_head->in(LoopNode::EntryControl);
1138     }
1139     return useblock;
1140   }
1141   return u_loop->_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1142 }
1143 
1144 
1145 bool PhaseIdealLoop::identical_backtoback_ifs(Node *n) {
1146   if (!n->is_If() || n->is_CountedLoopEnd()) {
1147     return false;
1148   }
1149   if (!n->in(0)->is_Region()) {
1150     return false;
1151   }
1152   Node* region = n->in(0);
1153   Node* dom = idom(region);
1154   if (!dom->is_If() || dom->in(1) != n->in(1)) {
1155     return false;
1156   }
1157   IfNode* dom_if = dom->as_If();
1158   Node* proj_true = dom_if->proj_out(1);
1159   Node* proj_false = dom_if->proj_out(0);
1160 
1161   for (uint i = 1; i < region->req(); i++) {
1162     if (is_dominator(proj_true, region->in(i))) {
1163       continue;
1164     }
1165     if (is_dominator(proj_false, region->in(i))) {
1166       continue;
1167     }
1168     return false;
1169   }
1170 
1171   return true;
1172 }
1173 
1174 
1175 bool PhaseIdealLoop::can_split_if(Node* n_ctrl) {
1176   if (must_throttle_split_if()) {
1177     return false;
1178   }
1179 
1180   // Do not do 'split-if' if irreducible loops are present.
1181   if (_has_irreducible_loops) {
1182     return false;
1183   }
1184 
1185   if (merge_point_too_heavy(C, n_ctrl)) {
1186     return false;
1187   }
1188 
1189   // Do not do 'split-if' if some paths are dead.  First do dead code
1190   // elimination and then see if its still profitable.
1191   for (uint i = 1; i < n_ctrl->req(); i++) {
1192     if (n_ctrl->in(i) == C->top()) {
1193       return false;
1194     }
1195   }
1196 
1197   // If trying to do a 'Split-If' at the loop head, it is only
1198   // profitable if the cmp folds up on BOTH paths.  Otherwise we
1199   // risk peeling a loop forever.
1200 
1201   // CNC - Disabled for now.  Requires careful handling of loop
1202   // body selection for the cloned code.  Also, make sure we check
1203   // for any input path not being in the same loop as n_ctrl.  For
1204   // irreducible loops we cannot check for 'n_ctrl->is_Loop()'
1205   // because the alternative loop entry points won't be converted
1206   // into LoopNodes.
1207   IdealLoopTree *n_loop = get_loop(n_ctrl);
1208   for (uint j = 1; j < n_ctrl->req(); j++) {
1209     if (get_loop(n_ctrl->in(j)) != n_loop) {
1210       return false;
1211     }
1212   }
1213 
1214   // Check for safety of the merge point.
1215   if (!merge_point_safe(n_ctrl)) {
1216     return false;
1217   }
1218 
1219   return true;
1220 }
1221 
1222 // Detect if the node is the inner strip-mined loop
1223 // Return: NULL if it's not the case, or the exit of outer strip-mined loop
1224 static Node* is_inner_of_stripmined_loop(const Node* out) {
1225   Node* out_le = NULL;
1226 
1227   if (out->is_CountedLoopEnd()) {
1228       const CountedLoopNode* loop = out->as_CountedLoopEnd()->loopnode();
1229 
1230       if (loop != NULL && loop->is_strip_mined()) {
1231         out_le = loop->in(LoopNode::EntryControl)->as_OuterStripMinedLoop()->outer_loop_exit();
1232       }
1233   }
1234 
1235   return out_le;
1236 }
1237 
1238 //------------------------------split_if_with_blocks_post----------------------
1239 // Do the real work in a non-recursive function.  CFG hackery wants to be
1240 // in the post-order, so it can dirty the I-DOM info and not use the dirtied
1241 // info.
1242 void PhaseIdealLoop::split_if_with_blocks_post(Node *n) {
1243 
1244   // Cloning Cmp through Phi's involves the split-if transform.
1245   // FastLock is not used by an If
1246   if (n->is_Cmp() && !n->is_FastLock()) {
1247     Node *n_ctrl = get_ctrl(n);
1248     // Determine if the Node has inputs from some local Phi.
1249     // Returns the block to clone thru.
1250     Node *n_blk = has_local_phi_input(n);
1251     if (n_blk != n_ctrl) {
1252       return;
1253     }
1254 
1255     if (!can_split_if(n_ctrl)) {
1256       return;
1257     }
1258 
1259     if (n->outcnt() != 1) {
1260       return; // Multiple bool's from 1 compare?
1261     }
1262     Node *bol = n->unique_out();
1263     assert(bol->is_Bool(), "expect a bool here");
1264     if (bol->outcnt() != 1) {
1265       return;// Multiple branches from 1 compare?
1266     }
1267     Node *iff = bol->unique_out();
1268 
1269     // Check some safety conditions
1270     if (iff->is_If()) {        // Classic split-if?
1271       if (iff->in(0) != n_ctrl) {
1272         return; // Compare must be in same blk as if
1273       }
1274     } else if (iff->is_CMove()) { // Trying to split-up a CMOVE
1275       // Can't split CMove with different control edge.
1276       if (iff->in(0) != NULL && iff->in(0) != n_ctrl ) {
1277         return;
1278       }
1279       if (get_ctrl(iff->in(2)) == n_ctrl ||
1280           get_ctrl(iff->in(3)) == n_ctrl) {
1281         return;                 // Inputs not yet split-up
1282       }
1283       if (get_loop(n_ctrl) != get_loop(get_ctrl(iff))) {
1284         return;                 // Loop-invar test gates loop-varying CMOVE
1285       }
1286     } else {
1287       return;  // some other kind of node, such as an Allocate
1288     }
1289 
1290     // When is split-if profitable?  Every 'win' on means some control flow
1291     // goes dead, so it's almost always a win.
1292     int policy = 0;
1293     // Split compare 'n' through the merge point if it is profitable
1294     Node *phi = split_thru_phi( n, n_ctrl, policy);
1295     if (!phi) {
1296       return;
1297     }
1298 
1299     // Found a Phi to split thru!
1300     // Replace 'n' with the new phi
1301     _igvn.replace_node(n, phi);
1302 
1303     // Now split the bool up thru the phi
1304     Node *bolphi = split_thru_phi(bol, n_ctrl, -1);
1305     guarantee(bolphi != NULL, "null boolean phi node");
1306 
1307     _igvn.replace_node(bol, bolphi);
1308     assert(iff->in(1) == bolphi, "");
1309 
1310     if (bolphi->Value(&_igvn)->singleton()) {
1311       return;
1312     }
1313 
1314     // Conditional-move?  Must split up now
1315     if (!iff->is_If()) {
1316       Node *cmovphi = split_thru_phi(iff, n_ctrl, -1);
1317       _igvn.replace_node(iff, cmovphi);
1318       return;
1319     }
1320 
1321     // Now split the IF
1322     do_split_if(iff);
1323     return;
1324   }
1325 
1326   // Two identical ifs back to back can be merged
1327   if (identical_backtoback_ifs(n) && can_split_if(n->in(0))) {
1328     Node *n_ctrl = n->in(0);
1329     PhiNode* bolphi = PhiNode::make_blank(n_ctrl, n->in(1));
1330     IfNode* dom_if = idom(n_ctrl)->as_If();
1331     Node* proj_true = dom_if->proj_out(1);
1332     Node* proj_false = dom_if->proj_out(0);
1333     Node* con_true = _igvn.makecon(TypeInt::ONE);
1334     Node* con_false = _igvn.makecon(TypeInt::ZERO);
1335 
1336     for (uint i = 1; i < n_ctrl->req(); i++) {
1337       if (is_dominator(proj_true, n_ctrl->in(i))) {
1338         bolphi->init_req(i, con_true);
1339       } else {
1340         assert(is_dominator(proj_false, n_ctrl->in(i)), "bad if");
1341         bolphi->init_req(i, con_false);
1342       }
1343     }
1344     register_new_node(bolphi, n_ctrl);
1345     _igvn.replace_input_of(n, 1, bolphi);
1346 
1347     // Now split the IF
1348     do_split_if(n);
1349     return;
1350   }
1351 
1352   // Check for an IF ready to split; one that has its
1353   // condition codes input coming from a Phi at the block start.
1354   int n_op = n->Opcode();
1355 
1356   // Check for an IF being dominated by another IF same test
1357   if (n_op == Op_If ||
1358       n_op == Op_RangeCheck) {
1359     Node *bol = n->in(1);
1360     uint max = bol->outcnt();
1361     // Check for same test used more than once?
1362     if (max > 1 && bol->is_Bool()) {
1363       // Search up IDOMs to see if this IF is dominated.
1364       Node *cutoff = get_ctrl(bol);
1365 
1366       // Now search up IDOMs till cutoff, looking for a dominating test
1367       Node *prevdom = n;
1368       Node *dom = idom(prevdom);
1369       while (dom != cutoff) {
1370         if (dom->req() > 1 && dom->in(1) == bol && prevdom->in(0) == dom) {
1371           // It's invalid to move control dependent data nodes in the inner
1372           // strip-mined loop, because:
1373           //  1) break validation of LoopNode::verify_strip_mined()
1374           //  2) move code with side-effect in strip-mined loop
1375           // Move to the exit of outer strip-mined loop in that case.
1376           Node* out_le = is_inner_of_stripmined_loop(dom);
1377           if (out_le != NULL) {
1378             prevdom = out_le;
1379           }
1380           // Replace the dominated test with an obvious true or false.
1381           // Place it on the IGVN worklist for later cleanup.
1382           C->set_major_progress();
1383           dominated_by(prevdom, n, false, true);
1384 #ifndef PRODUCT
1385           if( VerifyLoopOptimizations ) verify();
1386 #endif
1387           return;
1388         }
1389         prevdom = dom;
1390         dom = idom(prevdom);
1391       }
1392     }
1393   }
1394 
1395   // See if a shared loop-varying computation has no loop-varying uses.
1396   // Happens if something is only used for JVM state in uncommon trap exits,
1397   // like various versions of induction variable+offset.  Clone the
1398   // computation per usage to allow it to sink out of the loop.
1399   if (has_ctrl(n) && !n->in(0)) {// n not dead and has no control edge (can float about)
1400     Node *n_ctrl = get_ctrl(n);
1401     IdealLoopTree *n_loop = get_loop(n_ctrl);
1402     if( n_loop != _ltree_root ) {
1403       DUIterator_Fast imax, i = n->fast_outs(imax);
1404       for (; i < imax; i++) {
1405         Node* u = n->fast_out(i);
1406         if( !has_ctrl(u) )     break; // Found control user
1407         IdealLoopTree *u_loop = get_loop(get_ctrl(u));
1408         if( u_loop == n_loop ) break; // Found loop-varying use
1409         if( n_loop->is_member( u_loop ) ) break; // Found use in inner loop
1410         if( u->Opcode() == Op_Opaque1 ) break; // Found loop limit, bugfix for 4677003
1411       }
1412       bool did_break = (i < imax);  // Did we break out of the previous loop?
1413       if (!did_break && n->outcnt() > 1) { // All uses in outer loops!
1414         Node* late_load_ctrl = NULL;
1415         Node* outer_strip_mined_loop_exit = NULL;
1416         if (n->is_Load()) {
1417           // If n is a load, get and save the result from get_late_ctrl(),
1418           // to be later used in calculating the control for n's clones.
1419           clear_dom_lca_tags();
1420           late_load_ctrl = get_late_ctrl(n, n_ctrl);
1421           if (n_loop->head()->is_Loop() && n_loop->head()->as_Loop()->is_strip_mined() && !n_loop->head()->is_OuterStripMinedLoop()
1422               && n_loop->tail()->in(0) == late_load_ctrl->in(0)) {
1423              // late_load_ctrl is a loop exit of an inner loop of an outer strip mined loop.
1424              // Use the outer strip mined loop exit instead later if it dominates x_ctrl.
1425              outer_strip_mined_loop_exit = n_loop->_parent->head()->as_OuterStripMinedLoop()->outer_loop_exit();
1426           }
1427         }
1428 
1429         // If n is a load, and the late control is the same as the current
1430         // control, then the cloning of n is a pointless exercise, because
1431         // GVN will ensure that we end up where we started.
1432         if (!n->is_Load() || late_load_ctrl != n_ctrl) {
1433           for (DUIterator_Last jmin, j = n->last_outs(jmin); j >= jmin; ) {
1434             Node *u = n->last_out(j); // Clone private computation per use
1435             _igvn.rehash_node_delayed(u);
1436             Node *x = n->clone(); // Clone computation
1437             Node *x_ctrl = NULL;
1438             if( u->is_Phi() ) {
1439               // Replace all uses of normal nodes.  Replace Phi uses
1440               // individually, so the separate Nodes can sink down
1441               // different paths.
1442               uint k = 1;
1443               while( u->in(k) != n ) k++;
1444               u->set_req( k, x );
1445               // x goes next to Phi input path
1446               x_ctrl = u->in(0)->in(k);
1447               --j;
1448             } else {              // Normal use
1449               // Replace all uses
1450               for( uint k = 0; k < u->req(); k++ ) {
1451                 if( u->in(k) == n ) {
1452                   u->set_req( k, x );
1453                   --j;
1454                 }
1455               }
1456               x_ctrl = get_ctrl(u);
1457             }
1458 
1459             // Find control for 'x' next to use but not inside inner loops.
1460             // For inner loop uses get the preheader area.
1461             x_ctrl = place_near_use(x_ctrl);
1462 
1463             if (n->is_Load()) {
1464               // For loads, add a control edge to a CFG node outside of the loop
1465               // to force them to not combine and return back inside the loop
1466               // during GVN optimization (4641526).
1467               //
1468               // Because we are setting the actual control input, factor in the result from get_late_ctrl() so we respect
1469               // any anti-dependences (6233005). If late_load_ctrl is an inner loop exit inside an outer strip mined loop
1470               // whose exit dominates the latest possible placement for x, then use this outer strip mined loop exit
1471               // instead of the inner loop exit (= late_load_ctrl) to move the load completely out of the loop.
1472               // This still respects any anti-dependencies in get_late_ctrl().
1473               if (outer_strip_mined_loop_exit != NULL && is_dominator(outer_strip_mined_loop_exit, get_late_ctrl(x, late_load_ctrl))) {
1474                 assert(dom_lca(outer_strip_mined_loop_exit, x_ctrl) == outer_strip_mined_loop_exit, "must be the same result");
1475                 x_ctrl = outer_strip_mined_loop_exit;
1476               } else {
1477                 x_ctrl = dom_lca(late_load_ctrl, x_ctrl);
1478               }
1479 
1480               // Don't allow the control input to be a CFG splitting node.
1481               // Such nodes should only have ProjNodes as outs, e.g. IfNode
1482               // should only have IfTrueNode and IfFalseNode (4985384).
1483               x_ctrl = find_non_split_ctrl(x_ctrl);
1484 
1485               IdealLoopTree* x_loop = get_loop(x_ctrl);
1486               Node* x_head = x_loop->_head;
1487               if (x_head->is_Loop() && (x_head->is_OuterStripMinedLoop() || x_head->as_Loop()->is_strip_mined()) && is_dominator(n_ctrl, x_head)) {
1488                 // Anti dependence analysis is sometimes too
1489                 // conservative: a store in the outer strip mined loop
1490                 // can prevent a load from floating out of the outer
1491                 // strip mined loop but the load may not be referenced
1492                 // from the safepoint: loop strip mining verification
1493                 // code reports a problem in that case. Make sure the
1494                 // load is not moved in the outer strip mined loop in
1495                 // that case.
1496                 x_ctrl = x_head->as_Loop()->skip_strip_mined()->in(LoopNode::EntryControl);
1497               }
1498               assert(dom_depth(n_ctrl) <= dom_depth(x_ctrl), "n is later than its clone");
1499 
1500               x->set_req(0, x_ctrl);
1501             }
1502             register_new_node(x, x_ctrl);
1503 
1504             // Some institutional knowledge is needed here: 'x' is
1505             // yanked because if the optimizer runs GVN on it all the
1506             // cloned x's will common up and undo this optimization and
1507             // be forced back in the loop.
1508             // I tried setting control edges on the x's to force them to
1509             // not combine, but the matching gets worried when it tries
1510             // to fold a StoreP and an AddP together (as part of an
1511             // address expression) and the AddP and StoreP have
1512             // different controls.
1513             if (!x->is_Load() && !x->is_DecodeNarrowPtr()) _igvn._worklist.yank(x);
1514           }
1515           _igvn.remove_dead_node(n);
1516         }
1517       }
1518     }
1519   }
1520 
1521   try_move_store_after_loop(n);
1522 
1523   // Check for Opaque2's who's loop has disappeared - who's input is in the
1524   // same loop nest as their output.  Remove 'em, they are no longer useful.
1525   if( n_op == Op_Opaque2 &&
1526       n->in(1) != NULL &&
1527       get_loop(get_ctrl(n)) == get_loop(get_ctrl(n->in(1))) ) {
1528     _igvn.replace_node( n, n->in(1) );
1529   }
1530 }
1531 
1532 //------------------------------split_if_with_blocks---------------------------
1533 // Check for aggressive application of 'split-if' optimization,
1534 // using basic block level info.
1535 void PhaseIdealLoop::split_if_with_blocks(VectorSet &visited, Node_Stack &nstack) {
1536   Node* root = C->root();
1537   visited.set(root->_idx); // first, mark root as visited
1538   // Do pre-visit work for root
1539   Node* n   = split_if_with_blocks_pre(root);
1540   uint  cnt = n->outcnt();
1541   uint  i   = 0;
1542 
1543   while (true) {
1544     // Visit all children
1545     if (i < cnt) {
1546       Node* use = n->raw_out(i);
1547       ++i;
1548       if (use->outcnt() != 0 && !visited.test_set(use->_idx)) {
1549         // Now do pre-visit work for this use
1550         use = split_if_with_blocks_pre(use);
1551         nstack.push(n, i); // Save parent and next use's index.
1552         n   = use;         // Process all children of current use.
1553         cnt = use->outcnt();
1554         i   = 0;
1555       }
1556     }
1557     else {
1558       // All of n's children have been processed, complete post-processing.
1559       if (cnt != 0 && !n->is_Con()) {
1560         assert(has_node(n), "no dead nodes");
1561         split_if_with_blocks_post(n);
1562       }
1563       if (must_throttle_split_if()) {
1564         nstack.clear();
1565       }
1566       if (nstack.is_empty()) {
1567         // Finished all nodes on stack.
1568         break;
1569       }
1570       // Get saved parent node and next use's index. Visit the rest of uses.
1571       n   = nstack.node();
1572       cnt = n->outcnt();
1573       i   = nstack.index();
1574       nstack.pop();
1575     }
1576   }
1577 }
1578 
1579 
1580 //=============================================================================
1581 //
1582 //                   C L O N E   A   L O O P   B O D Y
1583 //
1584 
1585 //------------------------------clone_iff--------------------------------------
1586 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1587 // "Nearly" because all Nodes have been cloned from the original in the loop,
1588 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1589 // through the Phi recursively, and return a Bool.
1590 Node* PhaseIdealLoop::clone_iff(PhiNode *phi, IdealLoopTree *loop) {
1591 
1592   // Convert this Phi into a Phi merging Bools
1593   uint i;
1594   for (i = 1; i < phi->req(); i++) {
1595     Node *b = phi->in(i);
1596     if (b->is_Phi()) {
1597       _igvn.replace_input_of(phi, i, clone_iff(b->as_Phi(), loop));
1598     } else {
1599       assert(b->is_Bool() || b->Opcode() == Op_Opaque4, "");
1600     }
1601   }
1602 
1603   Node* n = phi->in(1);
1604   Node* sample_opaque = NULL;
1605   Node *sample_bool = NULL;
1606   if (n->Opcode() == Op_Opaque4) {
1607     sample_opaque = n;
1608     sample_bool = n->in(1);
1609     assert(sample_bool->is_Bool(), "wrong type");
1610   } else {
1611     sample_bool = n;
1612   }
1613   Node *sample_cmp = sample_bool->in(1);
1614 
1615   // Make Phis to merge the Cmp's inputs.
1616   PhiNode *phi1 = new PhiNode(phi->in(0), Type::TOP);
1617   PhiNode *phi2 = new PhiNode(phi->in(0), Type::TOP);
1618   for (i = 1; i < phi->req(); i++) {
1619     Node *n1 = sample_opaque == NULL ? phi->in(i)->in(1)->in(1) : phi->in(i)->in(1)->in(1)->in(1);
1620     Node *n2 = sample_opaque == NULL ? phi->in(i)->in(1)->in(2) : phi->in(i)->in(1)->in(1)->in(2);
1621     phi1->set_req(i, n1);
1622     phi2->set_req(i, n2);
1623     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1624     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1625   }
1626   // See if these Phis have been made before.
1627   // Register with optimizer
1628   Node *hit1 = _igvn.hash_find_insert(phi1);
1629   if (hit1) {                   // Hit, toss just made Phi
1630     _igvn.remove_dead_node(phi1); // Remove new phi
1631     assert(hit1->is_Phi(), "" );
1632     phi1 = (PhiNode*)hit1;      // Use existing phi
1633   } else {                      // Miss
1634     _igvn.register_new_node_with_optimizer(phi1);
1635   }
1636   Node *hit2 = _igvn.hash_find_insert(phi2);
1637   if (hit2) {                   // Hit, toss just made Phi
1638     _igvn.remove_dead_node(phi2); // Remove new phi
1639     assert(hit2->is_Phi(), "" );
1640     phi2 = (PhiNode*)hit2;      // Use existing phi
1641   } else {                      // Miss
1642     _igvn.register_new_node_with_optimizer(phi2);
1643   }
1644   // Register Phis with loop/block info
1645   set_ctrl(phi1, phi->in(0));
1646   set_ctrl(phi2, phi->in(0));
1647   // Make a new Cmp
1648   Node *cmp = sample_cmp->clone();
1649   cmp->set_req(1, phi1);
1650   cmp->set_req(2, phi2);
1651   _igvn.register_new_node_with_optimizer(cmp);
1652   set_ctrl(cmp, phi->in(0));
1653 
1654   // Make a new Bool
1655   Node *b = sample_bool->clone();
1656   b->set_req(1,cmp);
1657   _igvn.register_new_node_with_optimizer(b);
1658   set_ctrl(b, phi->in(0));
1659 
1660   if (sample_opaque != NULL) {
1661     Node* opaque = sample_opaque->clone();
1662     opaque->set_req(1, b);
1663     _igvn.register_new_node_with_optimizer(opaque);
1664     set_ctrl(opaque, phi->in(0));
1665     return opaque;
1666   }
1667 
1668   assert(b->is_Bool(), "");
1669   return b;
1670 }
1671 
1672 //------------------------------clone_bool-------------------------------------
1673 // Passed in a Phi merging (recursively) some nearly equivalent Bool/Cmps.
1674 // "Nearly" because all Nodes have been cloned from the original in the loop,
1675 // but the fall-in edges to the Cmp are different.  Clone bool/Cmp pairs
1676 // through the Phi recursively, and return a Bool.
1677 CmpNode *PhaseIdealLoop::clone_bool( PhiNode *phi, IdealLoopTree *loop ) {
1678   uint i;
1679   // Convert this Phi into a Phi merging Bools
1680   for( i = 1; i < phi->req(); i++ ) {
1681     Node *b = phi->in(i);
1682     if( b->is_Phi() ) {
1683       _igvn.replace_input_of(phi, i, clone_bool( b->as_Phi(), loop ));
1684     } else {
1685       assert( b->is_Cmp() || b->is_top(), "inputs are all Cmp or TOP" );
1686     }
1687   }
1688 
1689   Node *sample_cmp = phi->in(1);
1690 
1691   // Make Phis to merge the Cmp's inputs.
1692   PhiNode *phi1 = new PhiNode( phi->in(0), Type::TOP );
1693   PhiNode *phi2 = new PhiNode( phi->in(0), Type::TOP );
1694   for( uint j = 1; j < phi->req(); j++ ) {
1695     Node *cmp_top = phi->in(j); // Inputs are all Cmp or TOP
1696     Node *n1, *n2;
1697     if( cmp_top->is_Cmp() ) {
1698       n1 = cmp_top->in(1);
1699       n2 = cmp_top->in(2);
1700     } else {
1701       n1 = n2 = cmp_top;
1702     }
1703     phi1->set_req( j, n1 );
1704     phi2->set_req( j, n2 );
1705     phi1->set_type(phi1->type()->meet_speculative(n1->bottom_type()));
1706     phi2->set_type(phi2->type()->meet_speculative(n2->bottom_type()));
1707   }
1708 
1709   // See if these Phis have been made before.
1710   // Register with optimizer
1711   Node *hit1 = _igvn.hash_find_insert(phi1);
1712   if( hit1 ) {                  // Hit, toss just made Phi
1713     _igvn.remove_dead_node(phi1); // Remove new phi
1714     assert( hit1->is_Phi(), "" );
1715     phi1 = (PhiNode*)hit1;      // Use existing phi
1716   } else {                      // Miss
1717     _igvn.register_new_node_with_optimizer(phi1);
1718   }
1719   Node *hit2 = _igvn.hash_find_insert(phi2);
1720   if( hit2 ) {                  // Hit, toss just made Phi
1721     _igvn.remove_dead_node(phi2); // Remove new phi
1722     assert( hit2->is_Phi(), "" );
1723     phi2 = (PhiNode*)hit2;      // Use existing phi
1724   } else {                      // Miss
1725     _igvn.register_new_node_with_optimizer(phi2);
1726   }
1727   // Register Phis with loop/block info
1728   set_ctrl(phi1, phi->in(0));
1729   set_ctrl(phi2, phi->in(0));
1730   // Make a new Cmp
1731   Node *cmp = sample_cmp->clone();
1732   cmp->set_req( 1, phi1 );
1733   cmp->set_req( 2, phi2 );
1734   _igvn.register_new_node_with_optimizer(cmp);
1735   set_ctrl(cmp, phi->in(0));
1736 
1737   assert( cmp->is_Cmp(), "" );
1738   return (CmpNode*)cmp;
1739 }
1740 
1741 //------------------------------sink_use---------------------------------------
1742 // If 'use' was in the loop-exit block, it now needs to be sunk
1743 // below the post-loop merge point.
1744 void PhaseIdealLoop::sink_use( Node *use, Node *post_loop ) {
1745   if (!use->is_CFG() && get_ctrl(use) == post_loop->in(2)) {
1746     set_ctrl(use, post_loop);
1747     for (DUIterator j = use->outs(); use->has_out(j); j++)
1748       sink_use(use->out(j), post_loop);
1749   }
1750 }
1751 
1752 void PhaseIdealLoop::clone_loop_handle_data_uses(Node* old, Node_List &old_new,
1753                                                  IdealLoopTree* loop, IdealLoopTree* outer_loop,
1754                                                  Node_List*& split_if_set, Node_List*& split_bool_set,
1755                                                  Node_List*& split_cex_set, Node_List& worklist,
1756                                                  uint new_counter, CloneLoopMode mode) {
1757   Node* nnn = old_new[old->_idx];
1758   // Copy uses to a worklist, so I can munge the def-use info
1759   // with impunity.
1760   for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
1761     worklist.push(old->fast_out(j));
1762 
1763   while( worklist.size() ) {
1764     Node *use = worklist.pop();
1765     if (!has_node(use))  continue; // Ignore dead nodes
1766     if (use->in(0) == C->top())  continue;
1767     IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
1768     // Check for data-use outside of loop - at least one of OLD or USE
1769     // must not be a CFG node.
1770 #ifdef ASSERT
1771     if (loop->_head->as_Loop()->is_strip_mined() && outer_loop->is_member(use_loop) && !loop->is_member(use_loop) && old_new[use->_idx] == NULL) {
1772       Node* sfpt = loop->_head->as_CountedLoop()->outer_safepoint();
1773       assert(mode != IgnoreStripMined, "incorrect cloning mode");
1774       assert((mode == ControlAroundStripMined && use == sfpt) || !use->is_reachable_from_root(), "missed a node");
1775     }
1776 #endif
1777     if (!loop->is_member(use_loop) && !outer_loop->is_member(use_loop) && (!old->is_CFG() || !use->is_CFG())) {
1778 
1779       // If the Data use is an IF, that means we have an IF outside of the
1780       // loop that is switching on a condition that is set inside of the
1781       // loop.  Happens if people set a loop-exit flag; then test the flag
1782       // in the loop to break the loop, then test is again outside of the
1783       // loop to determine which way the loop exited.
1784       // Loop predicate If node connects to Bool node through Opaque1 node.
1785       if (use->is_If() || use->is_CMove() || C->is_predicate_opaq(use) || use->Opcode() == Op_Opaque4) {
1786         // Since this code is highly unlikely, we lazily build the worklist
1787         // of such Nodes to go split.
1788         if (!split_if_set) {
1789           split_if_set = new Node_List();
1790         }
1791         split_if_set->push(use);
1792       }
1793       if (use->is_Bool()) {
1794         if (!split_bool_set) {
1795           split_bool_set = new Node_List();
1796         }
1797         split_bool_set->push(use);
1798       }
1799       if (use->Opcode() == Op_CreateEx) {
1800         if (!split_cex_set) {
1801           split_cex_set = new Node_List();
1802         }
1803         split_cex_set->push(use);
1804       }
1805 
1806 
1807       // Get "block" use is in
1808       uint idx = 0;
1809       while( use->in(idx) != old ) idx++;
1810       Node *prev = use->is_CFG() ? use : get_ctrl(use);
1811       assert(!loop->is_member(get_loop(prev)) && !outer_loop->is_member(get_loop(prev)), "" );
1812       Node *cfg = prev->_idx >= new_counter
1813         ? prev->in(2)
1814         : idom(prev);
1815       if( use->is_Phi() )     // Phi use is in prior block
1816         cfg = prev->in(idx);  // NOT in block of Phi itself
1817       if (cfg->is_top()) {    // Use is dead?
1818         _igvn.replace_input_of(use, idx, C->top());
1819         continue;
1820       }
1821 
1822       // If use is referenced through control edge... (idx == 0)
1823       if (mode == IgnoreStripMined && idx == 0) {
1824         LoopNode *head = loop->_head->as_Loop();
1825         if (head->is_strip_mined() && is_dominator(head->outer_loop_exit(), prev)) {
1826           // That node is outside the inner loop, leave it outside the
1827           // outer loop as well to not confuse verification code.
1828           assert(!loop->_parent->is_member(use_loop), "should be out of the outer loop");
1829           _igvn.replace_input_of(use, 0, head->outer_loop_exit());
1830           continue;
1831         }
1832       }
1833 
1834       while(!outer_loop->is_member(get_loop(cfg))) {
1835         prev = cfg;
1836         cfg = cfg->_idx >= new_counter ? cfg->in(2) : idom(cfg);
1837       }
1838       // If the use occurs after merging several exits from the loop, then
1839       // old value must have dominated all those exits.  Since the same old
1840       // value was used on all those exits we did not need a Phi at this
1841       // merge point.  NOW we do need a Phi here.  Each loop exit value
1842       // is now merged with the peeled body exit; each exit gets its own
1843       // private Phi and those Phis need to be merged here.
1844       Node *phi;
1845       if( prev->is_Region() ) {
1846         if( idx == 0 ) {      // Updating control edge?
1847           phi = prev;         // Just use existing control
1848         } else {              // Else need a new Phi
1849           phi = PhiNode::make( prev, old );
1850           // Now recursively fix up the new uses of old!
1851           for( uint i = 1; i < prev->req(); i++ ) {
1852             worklist.push(phi); // Onto worklist once for each 'old' input
1853           }
1854         }
1855       } else {
1856         // Get new RegionNode merging old and new loop exits
1857         prev = old_new[prev->_idx];
1858         assert( prev, "just made this in step 7" );
1859         if( idx == 0) {      // Updating control edge?
1860           phi = prev;         // Just use existing control
1861         } else {              // Else need a new Phi
1862           // Make a new Phi merging data values properly
1863           phi = PhiNode::make( prev, old );
1864           phi->set_req( 1, nnn );
1865         }
1866       }
1867       // If inserting a new Phi, check for prior hits
1868       if( idx != 0 ) {
1869         Node *hit = _igvn.hash_find_insert(phi);
1870         if( hit == NULL ) {
1871           _igvn.register_new_node_with_optimizer(phi); // Register new phi
1872         } else {                                      // or
1873           // Remove the new phi from the graph and use the hit
1874           _igvn.remove_dead_node(phi);
1875           phi = hit;                                  // Use existing phi
1876         }
1877         set_ctrl(phi, prev);
1878       }
1879       // Make 'use' use the Phi instead of the old loop body exit value
1880       _igvn.replace_input_of(use, idx, phi);
1881       if( use->_idx >= new_counter ) { // If updating new phis
1882         // Not needed for correctness, but prevents a weak assert
1883         // in AddPNode from tripping (when we end up with different
1884         // base & derived Phis that will become the same after
1885         // IGVN does CSE).
1886         Node *hit = _igvn.hash_find_insert(use);
1887         if( hit )             // Go ahead and re-hash for hits.
1888           _igvn.replace_node( use, hit );
1889       }
1890 
1891       // If 'use' was in the loop-exit block, it now needs to be sunk
1892       // below the post-loop merge point.
1893       sink_use( use, prev );
1894     }
1895   }
1896 }
1897 
1898 static void clone_outer_loop_helper(Node* n, const IdealLoopTree *loop, const IdealLoopTree* outer_loop,
1899                                     const Node_List &old_new, Unique_Node_List& wq, PhaseIdealLoop* phase,
1900                                     bool check_old_new) {
1901   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
1902     Node* u = n->fast_out(j);
1903     assert(check_old_new || old_new[u->_idx] == NULL, "shouldn't have been cloned");
1904     if (!u->is_CFG() && (!check_old_new || old_new[u->_idx] == NULL)) {
1905       Node* c = phase->get_ctrl(u);
1906       IdealLoopTree* u_loop = phase->get_loop(c);
1907       assert(!loop->is_member(u_loop), "can be in outer loop or out of both loops only");
1908       if (outer_loop->is_member(u_loop)) {
1909         wq.push(u);
1910       }
1911     }
1912   }
1913 }
1914 
1915 void PhaseIdealLoop::clone_outer_loop(LoopNode* head, CloneLoopMode mode, IdealLoopTree *loop,
1916                                       IdealLoopTree* outer_loop, int dd, Node_List &old_new,
1917                                       Node_List& extra_data_nodes) {
1918   if (head->is_strip_mined() && mode != IgnoreStripMined) {
1919     CountedLoopNode* cl = head->as_CountedLoop();
1920     Node* l = cl->outer_loop();
1921     Node* tail = cl->outer_loop_tail();
1922     IfNode* le = cl->outer_loop_end();
1923     Node* sfpt = cl->outer_safepoint();
1924     CountedLoopEndNode* cle = cl->loopexit();
1925     CountedLoopNode* new_cl = old_new[cl->_idx]->as_CountedLoop();
1926     CountedLoopEndNode* new_cle = new_cl->as_CountedLoop()->loopexit_or_null();
1927     Node* cle_out = cle->proj_out(false);
1928 
1929     Node* new_sfpt = NULL;
1930     Node* new_cle_out = cle_out->clone();
1931     old_new.map(cle_out->_idx, new_cle_out);
1932     if (mode == CloneIncludesStripMined) {
1933       // clone outer loop body
1934       Node* new_l = l->clone();
1935       Node* new_tail = tail->clone();
1936       IfNode* new_le = le->clone()->as_If();
1937       new_sfpt = sfpt->clone();
1938 
1939       set_loop(new_l, outer_loop->_parent);
1940       set_idom(new_l, new_l->in(LoopNode::EntryControl), dd);
1941       set_loop(new_cle_out, outer_loop->_parent);
1942       set_idom(new_cle_out, new_cle, dd);
1943       set_loop(new_sfpt, outer_loop->_parent);
1944       set_idom(new_sfpt, new_cle_out, dd);
1945       set_loop(new_le, outer_loop->_parent);
1946       set_idom(new_le, new_sfpt, dd);
1947       set_loop(new_tail, outer_loop->_parent);
1948       set_idom(new_tail, new_le, dd);
1949       set_idom(new_cl, new_l, dd);
1950 
1951       old_new.map(l->_idx, new_l);
1952       old_new.map(tail->_idx, new_tail);
1953       old_new.map(le->_idx, new_le);
1954       old_new.map(sfpt->_idx, new_sfpt);
1955 
1956       new_l->set_req(LoopNode::LoopBackControl, new_tail);
1957       new_l->set_req(0, new_l);
1958       new_tail->set_req(0, new_le);
1959       new_le->set_req(0, new_sfpt);
1960       new_sfpt->set_req(0, new_cle_out);
1961       new_cle_out->set_req(0, new_cle);
1962       new_cl->set_req(LoopNode::EntryControl, new_l);
1963 
1964       _igvn.register_new_node_with_optimizer(new_l);
1965       _igvn.register_new_node_with_optimizer(new_tail);
1966       _igvn.register_new_node_with_optimizer(new_le);
1967     } else {
1968       Node *newhead = old_new[loop->_head->_idx];
1969       newhead->as_Loop()->clear_strip_mined();
1970       _igvn.replace_input_of(newhead, LoopNode::EntryControl, newhead->in(LoopNode::EntryControl)->in(LoopNode::EntryControl));
1971       set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
1972     }
1973     // Look at data node that were assigned a control in the outer
1974     // loop: they are kept in the outer loop by the safepoint so start
1975     // from the safepoint node's inputs.
1976     IdealLoopTree* outer_loop = get_loop(l);
1977     Node_Stack stack(2);
1978     stack.push(sfpt, 1);
1979     uint new_counter = C->unique();
1980     while (stack.size() > 0) {
1981       Node* n = stack.node();
1982       uint i = stack.index();
1983       while (i < n->req() &&
1984              (n->in(i) == NULL ||
1985               !has_ctrl(n->in(i)) ||
1986               get_loop(get_ctrl(n->in(i))) != outer_loop ||
1987               (old_new[n->in(i)->_idx] != NULL && old_new[n->in(i)->_idx]->_idx >= new_counter))) {
1988         i++;
1989       }
1990       if (i < n->req()) {
1991         stack.set_index(i+1);
1992         stack.push(n->in(i), 0);
1993       } else {
1994         assert(old_new[n->_idx] == NULL || n == sfpt || old_new[n->_idx]->_idx < new_counter, "no clone yet");
1995         Node* m = n == sfpt ? new_sfpt : n->clone();
1996         if (m != NULL) {
1997           for (uint i = 0; i < n->req(); i++) {
1998             if (m->in(i) != NULL && old_new[m->in(i)->_idx] != NULL) {
1999               m->set_req(i, old_new[m->in(i)->_idx]);
2000             }
2001           }
2002         } else {
2003           assert(n == sfpt && mode != CloneIncludesStripMined, "where's the safepoint clone?");
2004         }
2005         if (n != sfpt) {
2006           extra_data_nodes.push(n);
2007           _igvn.register_new_node_with_optimizer(m);
2008           assert(get_ctrl(n) == cle_out, "what other control?");
2009           set_ctrl(m, new_cle_out);
2010           old_new.map(n->_idx, m);
2011         }
2012         stack.pop();
2013       }
2014     }
2015     if (mode == CloneIncludesStripMined) {
2016       _igvn.register_new_node_with_optimizer(new_sfpt);
2017       _igvn.register_new_node_with_optimizer(new_cle_out);
2018     }
2019     // Some other transformation may have pessimistically assign some
2020     // data nodes to the outer loop. Set their control so they are out
2021     // of the outer loop.
2022     ResourceMark rm;
2023     Unique_Node_List wq;
2024     for (uint i = 0; i < extra_data_nodes.size(); i++) {
2025       Node* old = extra_data_nodes.at(i);
2026       clone_outer_loop_helper(old, loop, outer_loop, old_new, wq, this, true);
2027     }
2028     Node* new_ctrl = cl->outer_loop_exit();
2029     assert(get_loop(new_ctrl) != outer_loop, "must be out of the loop nest");
2030     for (uint i = 0; i < wq.size(); i++) {
2031       Node* n = wq.at(i);
2032       set_ctrl(n, new_ctrl);
2033       clone_outer_loop_helper(n, loop, outer_loop, old_new, wq, this, false);
2034     }
2035   } else {
2036     Node *newhead = old_new[loop->_head->_idx];
2037     set_idom(newhead, newhead->in(LoopNode::EntryControl), dd);
2038   }
2039 }
2040 
2041 //------------------------------clone_loop-------------------------------------
2042 //
2043 //                   C L O N E   A   L O O P   B O D Y
2044 //
2045 // This is the basic building block of the loop optimizations.  It clones an
2046 // entire loop body.  It makes an old_new loop body mapping; with this mapping
2047 // you can find the new-loop equivalent to an old-loop node.  All new-loop
2048 // nodes are exactly equal to their old-loop counterparts, all edges are the
2049 // same.  All exits from the old-loop now have a RegionNode that merges the
2050 // equivalent new-loop path.  This is true even for the normal "loop-exit"
2051 // condition.  All uses of loop-invariant old-loop values now come from (one
2052 // or more) Phis that merge their new-loop equivalents.
2053 //
2054 // This operation leaves the graph in an illegal state: there are two valid
2055 // control edges coming from the loop pre-header to both loop bodies.  I'll
2056 // definitely have to hack the graph after running this transform.
2057 //
2058 // From this building block I will further edit edges to perform loop peeling
2059 // or loop unrolling or iteration splitting (Range-Check-Elimination), etc.
2060 //
2061 // Parameter side_by_size_idom:
2062 //   When side_by_size_idom is NULL, the dominator tree is constructed for
2063 //      the clone loop to dominate the original.  Used in construction of
2064 //      pre-main-post loop sequence.
2065 //   When nonnull, the clone and original are side-by-side, both are
2066 //      dominated by the side_by_side_idom node.  Used in construction of
2067 //      unswitched loops.
2068 void PhaseIdealLoop::clone_loop( IdealLoopTree *loop, Node_List &old_new, int dd,
2069                                 CloneLoopMode mode, Node* side_by_side_idom) {
2070 
2071   LoopNode* head = loop->_head->as_Loop();
2072   head->verify_strip_mined(1);
2073 
2074   if (C->do_vector_loop() && PrintOpto) {
2075     const char* mname = C->method()->name()->as_quoted_ascii();
2076     if (mname != NULL) {
2077       tty->print("PhaseIdealLoop::clone_loop: for vectorize method %s\n", mname);
2078     }
2079   }
2080 
2081   CloneMap& cm = C->clone_map();
2082   Dict* dict = cm.dict();
2083   if (C->do_vector_loop()) {
2084     cm.set_clone_idx(cm.max_gen()+1);
2085 #ifndef PRODUCT
2086     if (PrintOpto) {
2087       tty->print_cr("PhaseIdealLoop::clone_loop: _clone_idx %d", cm.clone_idx());
2088       loop->dump_head();
2089     }
2090 #endif
2091   }
2092 
2093   // Step 1: Clone the loop body.  Make the old->new mapping.
2094   uint i;
2095   for( i = 0; i < loop->_body.size(); i++ ) {
2096     Node *old = loop->_body.at(i);
2097     Node *nnn = old->clone();
2098     old_new.map( old->_idx, nnn );
2099     if (C->do_vector_loop()) {
2100       cm.verify_insert_and_clone(old, nnn, cm.clone_idx());
2101     }
2102     _igvn.register_new_node_with_optimizer(nnn);
2103   }
2104 
2105   IdealLoopTree* outer_loop = (head->is_strip_mined() && mode != IgnoreStripMined) ? get_loop(head->as_CountedLoop()->outer_loop()) : loop;
2106 
2107   // Step 2: Fix the edges in the new body.  If the old input is outside the
2108   // loop use it.  If the old input is INside the loop, use the corresponding
2109   // new node instead.
2110   for( i = 0; i < loop->_body.size(); i++ ) {
2111     Node *old = loop->_body.at(i);
2112     Node *nnn = old_new[old->_idx];
2113     // Fix CFG/Loop controlling the new node
2114     if (has_ctrl(old)) {
2115       set_ctrl(nnn, old_new[get_ctrl(old)->_idx]);
2116     } else {
2117       set_loop(nnn, outer_loop->_parent);
2118       if (old->outcnt() > 0) {
2119         set_idom( nnn, old_new[idom(old)->_idx], dd );
2120       }
2121     }
2122     // Correct edges to the new node
2123     for( uint j = 0; j < nnn->req(); j++ ) {
2124         Node *n = nnn->in(j);
2125         if( n ) {
2126           IdealLoopTree *old_in_loop = get_loop( has_ctrl(n) ? get_ctrl(n) : n );
2127           if( loop->is_member( old_in_loop ) )
2128             nnn->set_req(j, old_new[n->_idx]);
2129         }
2130     }
2131     _igvn.hash_find_insert(nnn);
2132   }
2133 
2134   Node_List extra_data_nodes; // data nodes in the outer strip mined loop
2135   clone_outer_loop(head, mode, loop, outer_loop, dd, old_new, extra_data_nodes);
2136 
2137   // Step 3: Now fix control uses.  Loop varying control uses have already
2138   // been fixed up (as part of all input edges in Step 2).  Loop invariant
2139   // control uses must be either an IfFalse or an IfTrue.  Make a merge
2140   // point to merge the old and new IfFalse/IfTrue nodes; make the use
2141   // refer to this.
2142   Node_List worklist;
2143   uint new_counter = C->unique();
2144   for( i = 0; i < loop->_body.size(); i++ ) {
2145     Node* old = loop->_body.at(i);
2146     if( !old->is_CFG() ) continue;
2147 
2148     // Copy uses to a worklist, so I can munge the def-use info
2149     // with impunity.
2150     for (DUIterator_Fast jmax, j = old->fast_outs(jmax); j < jmax; j++)
2151       worklist.push(old->fast_out(j));
2152 
2153     while( worklist.size() ) {  // Visit all uses
2154       Node *use = worklist.pop();
2155       if (!has_node(use))  continue; // Ignore dead nodes
2156       IdealLoopTree *use_loop = get_loop( has_ctrl(use) ? get_ctrl(use) : use );
2157       if( !loop->is_member( use_loop ) && use->is_CFG() ) {
2158         // Both OLD and USE are CFG nodes here.
2159         assert( use->is_Proj(), "" );
2160         Node* nnn = old_new[old->_idx];
2161 
2162         Node* newuse = NULL;
2163         if (head->is_strip_mined() && mode != IgnoreStripMined) {
2164           CountedLoopNode* cl = head->as_CountedLoop();
2165           CountedLoopEndNode* cle = cl->loopexit();
2166           Node* cle_out = cle->proj_out_or_null(false);
2167           if (use == cle_out) {
2168             IfNode* le = cl->outer_loop_end();
2169             use = le->proj_out(false);
2170             use_loop = get_loop(use);
2171             if (mode == CloneIncludesStripMined) {
2172               nnn = old_new[le->_idx];
2173             } else {
2174               newuse = old_new[cle_out->_idx];
2175             }
2176           }
2177         }
2178         if (newuse == NULL) {
2179           newuse = use->clone();
2180         }
2181 
2182         // Clone the loop exit control projection
2183         if (C->do_vector_loop()) {
2184           cm.verify_insert_and_clone(use, newuse, cm.clone_idx());
2185         }
2186         newuse->set_req(0,nnn);
2187         _igvn.register_new_node_with_optimizer(newuse);
2188         set_loop(newuse, use_loop);
2189         set_idom(newuse, nnn, dom_depth(nnn) + 1 );
2190 
2191         // We need a Region to merge the exit from the peeled body and the
2192         // exit from the old loop body.
2193         RegionNode *r = new RegionNode(3);
2194         // Map the old use to the new merge point
2195         old_new.map( use->_idx, r );
2196         uint dd_r = MIN2(dom_depth(newuse),dom_depth(use));
2197         assert( dd_r >= dom_depth(dom_lca(newuse,use)), "" );
2198 
2199         // The original user of 'use' uses 'r' instead.
2200         for (DUIterator_Last lmin, l = use->last_outs(lmin); l >= lmin;) {
2201           Node* useuse = use->last_out(l);
2202           _igvn.rehash_node_delayed(useuse);
2203           uint uses_found = 0;
2204           if( useuse->in(0) == use ) {
2205             useuse->set_req(0, r);
2206             uses_found++;
2207             if( useuse->is_CFG() ) {
2208               // This is not a dom_depth > dd_r because when new
2209               // control flow is constructed by a loop opt, a node and
2210               // its dominator can end up at the same dom_depth
2211               assert(dom_depth(useuse) >= dd_r, "");
2212               set_idom(useuse, r, dom_depth(useuse));
2213             }
2214           }
2215           for( uint k = 1; k < useuse->req(); k++ ) {
2216             if( useuse->in(k) == use ) {
2217               useuse->set_req(k, r);
2218               uses_found++;
2219               if (useuse->is_Loop() && k == LoopNode::EntryControl) {
2220                 // This is not a dom_depth > dd_r because when new
2221                 // control flow is constructed by a loop opt, a node
2222                 // and its dominator can end up at the same dom_depth
2223                 assert(dom_depth(useuse) >= dd_r , "");
2224                 set_idom(useuse, r, dom_depth(useuse));
2225               }
2226             }
2227           }
2228           l -= uses_found;    // we deleted 1 or more copies of this edge
2229         }
2230 
2231         // Now finish up 'r'
2232         r->set_req( 1, newuse );
2233         r->set_req( 2,    use );
2234         _igvn.register_new_node_with_optimizer(r);
2235         set_loop(r, use_loop);
2236         set_idom(r, !side_by_side_idom ? newuse->in(0) : side_by_side_idom, dd_r);
2237       } // End of if a loop-exit test
2238     }
2239   }
2240 
2241   // Step 4: If loop-invariant use is not control, it must be dominated by a
2242   // loop exit IfFalse/IfTrue.  Find "proper" loop exit.  Make a Region
2243   // there if needed.  Make a Phi there merging old and new used values.
2244   Node_List *split_if_set = NULL;
2245   Node_List *split_bool_set = NULL;
2246   Node_List *split_cex_set = NULL;
2247   for( i = 0; i < loop->_body.size(); i++ ) {
2248     Node* old = loop->_body.at(i);
2249     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2250                                 split_bool_set, split_cex_set, worklist, new_counter,
2251                                 mode);
2252   }
2253 
2254   for (i = 0; i < extra_data_nodes.size(); i++) {
2255     Node* old = extra_data_nodes.at(i);
2256     clone_loop_handle_data_uses(old, old_new, loop, outer_loop, split_if_set,
2257                                 split_bool_set, split_cex_set, worklist, new_counter,
2258                                 mode);
2259   }
2260 
2261   // Check for IFs that need splitting/cloning.  Happens if an IF outside of
2262   // the loop uses a condition set in the loop.  The original IF probably
2263   // takes control from one or more OLD Regions (which in turn get from NEW
2264   // Regions).  In any case, there will be a set of Phis for each merge point
2265   // from the IF up to where the original BOOL def exists the loop.
2266   if (split_if_set) {
2267     while (split_if_set->size()) {
2268       Node *iff = split_if_set->pop();
2269       if (iff->in(1)->is_Phi()) {
2270         Node *b = clone_iff(iff->in(1)->as_Phi(), loop);
2271         _igvn.replace_input_of(iff, 1, b);
2272       }
2273     }
2274   }
2275   if (split_bool_set) {
2276     while (split_bool_set->size()) {
2277       Node *b = split_bool_set->pop();
2278       Node *phi = b->in(1);
2279       assert(phi->is_Phi(), "");
2280       CmpNode *cmp = clone_bool((PhiNode*)phi, loop);
2281       _igvn.replace_input_of(b, 1, cmp);
2282     }
2283   }
2284   if (split_cex_set) {
2285     while (split_cex_set->size()) {
2286       Node *b = split_cex_set->pop();
2287       assert(b->in(0)->is_Region(), "");
2288       assert(b->in(1)->is_Phi(), "");
2289       assert(b->in(0)->in(0) == b->in(1)->in(0), "");
2290       split_up(b, b->in(0), NULL);
2291     }
2292   }
2293 
2294 }
2295 
2296 
2297 //---------------------- stride_of_possible_iv -------------------------------------
2298 // Looks for an iff/bool/comp with one operand of the compare
2299 // being a cycle involving an add and a phi,
2300 // with an optional truncation (left-shift followed by a right-shift)
2301 // of the add. Returns zero if not an iv.
2302 int PhaseIdealLoop::stride_of_possible_iv(Node* iff) {
2303   Node* trunc1 = NULL;
2304   Node* trunc2 = NULL;
2305   const TypeInt* ttype = NULL;
2306   if (!iff->is_If() || iff->in(1) == NULL || !iff->in(1)->is_Bool()) {
2307     return 0;
2308   }
2309   BoolNode* bl = iff->in(1)->as_Bool();
2310   Node* cmp = bl->in(1);
2311   if (!cmp || (cmp->Opcode() != Op_CmpI && cmp->Opcode() != Op_CmpU)) {
2312     return 0;
2313   }
2314   // Must have an invariant operand
2315   if (is_member(get_loop(iff), get_ctrl(cmp->in(2)))) {
2316     return 0;
2317   }
2318   Node* add2 = NULL;
2319   Node* cmp1 = cmp->in(1);
2320   if (cmp1->is_Phi()) {
2321     // (If (Bool (CmpX phi:(Phi ...(Optional-trunc(AddI phi add2))) )))
2322     Node* phi = cmp1;
2323     for (uint i = 1; i < phi->req(); i++) {
2324       Node* in = phi->in(i);
2325       Node* add = CountedLoopNode::match_incr_with_optional_truncation(in,
2326                                 &trunc1, &trunc2, &ttype);
2327       if (add && add->in(1) == phi) {
2328         add2 = add->in(2);
2329         break;
2330       }
2331     }
2332   } else {
2333     // (If (Bool (CmpX addtrunc:(Optional-trunc((AddI (Phi ...addtrunc...) add2)) )))
2334     Node* addtrunc = cmp1;
2335     Node* add = CountedLoopNode::match_incr_with_optional_truncation(addtrunc,
2336                                 &trunc1, &trunc2, &ttype);
2337     if (add && add->in(1)->is_Phi()) {
2338       Node* phi = add->in(1);
2339       for (uint i = 1; i < phi->req(); i++) {
2340         if (phi->in(i) == addtrunc) {
2341           add2 = add->in(2);
2342           break;
2343         }
2344       }
2345     }
2346   }
2347   if (add2 != NULL) {
2348     const TypeInt* add2t = _igvn.type(add2)->is_int();
2349     if (add2t->is_con()) {
2350       return add2t->get_con();
2351     }
2352   }
2353   return 0;
2354 }
2355 
2356 
2357 //---------------------- stay_in_loop -------------------------------------
2358 // Return the (unique) control output node that's in the loop (if it exists.)
2359 Node* PhaseIdealLoop::stay_in_loop( Node* n, IdealLoopTree *loop) {
2360   Node* unique = NULL;
2361   if (!n) return NULL;
2362   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2363     Node* use = n->fast_out(i);
2364     if (!has_ctrl(use) && loop->is_member(get_loop(use))) {
2365       if (unique != NULL) {
2366         return NULL;
2367       }
2368       unique = use;
2369     }
2370   }
2371   return unique;
2372 }
2373 
2374 //------------------------------ register_node -------------------------------------
2375 // Utility to register node "n" with PhaseIdealLoop
2376 void PhaseIdealLoop::register_node(Node* n, IdealLoopTree *loop, Node* pred, int ddepth) {
2377   _igvn.register_new_node_with_optimizer(n);
2378   loop->_body.push(n);
2379   if (n->is_CFG()) {
2380     set_loop(n, loop);
2381     set_idom(n, pred, ddepth);
2382   } else {
2383     set_ctrl(n, pred);
2384   }
2385 }
2386 
2387 //------------------------------ proj_clone -------------------------------------
2388 // Utility to create an if-projection
2389 ProjNode* PhaseIdealLoop::proj_clone(ProjNode* p, IfNode* iff) {
2390   ProjNode* c = p->clone()->as_Proj();
2391   c->set_req(0, iff);
2392   return c;
2393 }
2394 
2395 //------------------------------ short_circuit_if -------------------------------------
2396 // Force the iff control output to be the live_proj
2397 Node* PhaseIdealLoop::short_circuit_if(IfNode* iff, ProjNode* live_proj) {
2398   guarantee(live_proj != NULL, "null projection");
2399   int proj_con = live_proj->_con;
2400   assert(proj_con == 0 || proj_con == 1, "false or true projection");
2401   Node *con = _igvn.intcon(proj_con);
2402   set_ctrl(con, C->root());
2403   if (iff) {
2404     iff->set_req(1, con);
2405   }
2406   return con;
2407 }
2408 
2409 //------------------------------ insert_if_before_proj -------------------------------------
2410 // Insert a new if before an if projection (* - new node)
2411 //
2412 // before
2413 //           if(test)
2414 //           /     \
2415 //          v       v
2416 //    other-proj   proj (arg)
2417 //
2418 // after
2419 //           if(test)
2420 //           /     \
2421 //          /       v
2422 //         |      * proj-clone
2423 //         v          |
2424 //    other-proj      v
2425 //                * new_if(relop(cmp[IU](left,right)))
2426 //                  /  \
2427 //                 v    v
2428 //         * new-proj  proj
2429 //         (returned)
2430 //
2431 ProjNode* PhaseIdealLoop::insert_if_before_proj(Node* left, bool Signed, BoolTest::mask relop, Node* right, ProjNode* proj) {
2432   IfNode* iff = proj->in(0)->as_If();
2433   IdealLoopTree *loop = get_loop(proj);
2434   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2435   int ddepth = dom_depth(proj);
2436 
2437   _igvn.rehash_node_delayed(iff);
2438   _igvn.rehash_node_delayed(proj);
2439 
2440   proj->set_req(0, NULL);  // temporary disconnect
2441   ProjNode* proj2 = proj_clone(proj, iff);
2442   register_node(proj2, loop, iff, ddepth);
2443 
2444   Node* cmp = Signed ? (Node*) new CmpINode(left, right) : (Node*) new CmpUNode(left, right);
2445   register_node(cmp, loop, proj2, ddepth);
2446 
2447   BoolNode* bol = new BoolNode(cmp, relop);
2448   register_node(bol, loop, proj2, ddepth);
2449 
2450   int opcode = iff->Opcode();
2451   assert(opcode == Op_If || opcode == Op_RangeCheck, "unexpected opcode");
2452   IfNode* new_if = (opcode == Op_If) ? new IfNode(proj2, bol, iff->_prob, iff->_fcnt):
2453     new RangeCheckNode(proj2, bol, iff->_prob, iff->_fcnt);
2454   register_node(new_if, loop, proj2, ddepth);
2455 
2456   proj->set_req(0, new_if); // reattach
2457   set_idom(proj, new_if, ddepth);
2458 
2459   ProjNode* new_exit = proj_clone(other_proj, new_if)->as_Proj();
2460   guarantee(new_exit != NULL, "null exit node");
2461   register_node(new_exit, get_loop(other_proj), new_if, ddepth);
2462 
2463   return new_exit;
2464 }
2465 
2466 //------------------------------ insert_region_before_proj -------------------------------------
2467 // Insert a region before an if projection (* - new node)
2468 //
2469 // before
2470 //           if(test)
2471 //          /      |
2472 //         v       |
2473 //       proj      v
2474 //               other-proj
2475 //
2476 // after
2477 //           if(test)
2478 //          /      |
2479 //         v       |
2480 // * proj-clone    v
2481 //         |     other-proj
2482 //         v
2483 // * new-region
2484 //         |
2485 //         v
2486 // *      dum_if
2487 //       /     \
2488 //      v       \
2489 // * dum-proj    v
2490 //              proj
2491 //
2492 RegionNode* PhaseIdealLoop::insert_region_before_proj(ProjNode* proj) {
2493   IfNode* iff = proj->in(0)->as_If();
2494   IdealLoopTree *loop = get_loop(proj);
2495   ProjNode *other_proj = iff->proj_out(!proj->is_IfTrue())->as_Proj();
2496   int ddepth = dom_depth(proj);
2497 
2498   _igvn.rehash_node_delayed(iff);
2499   _igvn.rehash_node_delayed(proj);
2500 
2501   proj->set_req(0, NULL);  // temporary disconnect
2502   ProjNode* proj2 = proj_clone(proj, iff);
2503   register_node(proj2, loop, iff, ddepth);
2504 
2505   RegionNode* reg = new RegionNode(2);
2506   reg->set_req(1, proj2);
2507   register_node(reg, loop, iff, ddepth);
2508 
2509   IfNode* dum_if = new IfNode(reg, short_circuit_if(NULL, proj), iff->_prob, iff->_fcnt);
2510   register_node(dum_if, loop, reg, ddepth);
2511 
2512   proj->set_req(0, dum_if); // reattach
2513   set_idom(proj, dum_if, ddepth);
2514 
2515   ProjNode* dum_proj = proj_clone(other_proj, dum_if);
2516   register_node(dum_proj, loop, dum_if, ddepth);
2517 
2518   return reg;
2519 }
2520 
2521 //------------------------------ insert_cmpi_loop_exit -------------------------------------
2522 // Clone a signed compare loop exit from an unsigned compare and
2523 // insert it before the unsigned cmp on the stay-in-loop path.
2524 // All new nodes inserted in the dominator tree between the original
2525 // if and it's projections.  The original if test is replaced with
2526 // a constant to force the stay-in-loop path.
2527 //
2528 // This is done to make sure that the original if and it's projections
2529 // still dominate the same set of control nodes, that the ctrl() relation
2530 // from data nodes to them is preserved, and that their loop nesting is
2531 // preserved.
2532 //
2533 // before
2534 //          if(i <u limit)    unsigned compare loop exit
2535 //         /       |
2536 //        v        v
2537 //   exit-proj   stay-in-loop-proj
2538 //
2539 // after
2540 //          if(stay-in-loop-const)  original if
2541 //         /       |
2542 //        /        v
2543 //       /  if(i <  limit)    new signed test
2544 //      /  /       |
2545 //     /  /        v
2546 //    /  /  if(i <u limit)    new cloned unsigned test
2547 //   /  /   /      |
2548 //   v  v  v       |
2549 //    region       |
2550 //        |        |
2551 //      dum-if     |
2552 //     /  |        |
2553 // ether  |        |
2554 //        v        v
2555 //   exit-proj   stay-in-loop-proj
2556 //
2557 IfNode* PhaseIdealLoop::insert_cmpi_loop_exit(IfNode* if_cmpu, IdealLoopTree *loop) {
2558   const bool Signed   = true;
2559   const bool Unsigned = false;
2560 
2561   BoolNode* bol = if_cmpu->in(1)->as_Bool();
2562   if (bol->_test._test != BoolTest::lt) return NULL;
2563   CmpNode* cmpu = bol->in(1)->as_Cmp();
2564   if (cmpu->Opcode() != Op_CmpU) return NULL;
2565   int stride = stride_of_possible_iv(if_cmpu);
2566   if (stride == 0) return NULL;
2567 
2568   Node* lp_proj = stay_in_loop(if_cmpu, loop);
2569   guarantee(lp_proj != NULL, "null loop node");
2570 
2571   ProjNode* lp_continue = lp_proj->as_Proj();
2572   ProjNode* lp_exit     = if_cmpu->proj_out(!lp_continue->is_IfTrue())->as_Proj();
2573 
2574   Node* limit = NULL;
2575   if (stride > 0) {
2576     limit = cmpu->in(2);
2577   } else {
2578     limit = _igvn.makecon(TypeInt::ZERO);
2579     set_ctrl(limit, C->root());
2580   }
2581   // Create a new region on the exit path
2582   RegionNode* reg = insert_region_before_proj(lp_exit);
2583   guarantee(reg != NULL, "null region node");
2584 
2585   // Clone the if-cmpu-true-false using a signed compare
2586   BoolTest::mask rel_i = stride > 0 ? bol->_test._test : BoolTest::ge;
2587   ProjNode* cmpi_exit = insert_if_before_proj(cmpu->in(1), Signed, rel_i, limit, lp_continue);
2588   reg->add_req(cmpi_exit);
2589 
2590   // Clone the if-cmpu-true-false
2591   BoolTest::mask rel_u = bol->_test._test;
2592   ProjNode* cmpu_exit = insert_if_before_proj(cmpu->in(1), Unsigned, rel_u, cmpu->in(2), lp_continue);
2593   reg->add_req(cmpu_exit);
2594 
2595   // Force original if to stay in loop.
2596   short_circuit_if(if_cmpu, lp_continue);
2597 
2598   return cmpi_exit->in(0)->as_If();
2599 }
2600 
2601 //------------------------------ remove_cmpi_loop_exit -------------------------------------
2602 // Remove a previously inserted signed compare loop exit.
2603 void PhaseIdealLoop::remove_cmpi_loop_exit(IfNode* if_cmp, IdealLoopTree *loop) {
2604   Node* lp_proj = stay_in_loop(if_cmp, loop);
2605   assert(if_cmp->in(1)->in(1)->Opcode() == Op_CmpI &&
2606          stay_in_loop(lp_proj, loop)->is_If() &&
2607          stay_in_loop(lp_proj, loop)->in(1)->in(1)->Opcode() == Op_CmpU, "inserted cmpi before cmpu");
2608   Node *con = _igvn.makecon(lp_proj->is_IfTrue() ? TypeInt::ONE : TypeInt::ZERO);
2609   set_ctrl(con, C->root());
2610   if_cmp->set_req(1, con);
2611 }
2612 
2613 //------------------------------ scheduled_nodelist -------------------------------------
2614 // Create a post order schedule of nodes that are in the
2615 // "member" set.  The list is returned in "sched".
2616 // The first node in "sched" is the loop head, followed by
2617 // nodes which have no inputs in the "member" set, and then
2618 // followed by the nodes that have an immediate input dependence
2619 // on a node in "sched".
2620 void PhaseIdealLoop::scheduled_nodelist( IdealLoopTree *loop, VectorSet& member, Node_List &sched ) {
2621 
2622   assert(member.test(loop->_head->_idx), "loop head must be in member set");
2623   VectorSet visited;
2624   Node_Stack nstack(loop->_body.size());
2625 
2626   Node* n  = loop->_head;  // top of stack is cached in "n"
2627   uint idx = 0;
2628   visited.set(n->_idx);
2629 
2630   // Initially push all with no inputs from within member set
2631   for(uint i = 0; i < loop->_body.size(); i++ ) {
2632     Node *elt = loop->_body.at(i);
2633     if (member.test(elt->_idx)) {
2634       bool found = false;
2635       for (uint j = 0; j < elt->req(); j++) {
2636         Node* def = elt->in(j);
2637         if (def && member.test(def->_idx) && def != elt) {
2638           found = true;
2639           break;
2640         }
2641       }
2642       if (!found && elt != loop->_head) {
2643         nstack.push(n, idx);
2644         n = elt;
2645         assert(!visited.test(n->_idx), "not seen yet");
2646         visited.set(n->_idx);
2647       }
2648     }
2649   }
2650 
2651   // traverse out's that are in the member set
2652   while (true) {
2653     if (idx < n->outcnt()) {
2654       Node* use = n->raw_out(idx);
2655       idx++;
2656       if (!visited.test_set(use->_idx)) {
2657         if (member.test(use->_idx)) {
2658           nstack.push(n, idx);
2659           n = use;
2660           idx = 0;
2661         }
2662       }
2663     } else {
2664       // All outputs processed
2665       sched.push(n);
2666       if (nstack.is_empty()) break;
2667       n   = nstack.node();
2668       idx = nstack.index();
2669       nstack.pop();
2670     }
2671   }
2672 }
2673 
2674 
2675 //------------------------------ has_use_in_set -------------------------------------
2676 // Has a use in the vector set
2677 bool PhaseIdealLoop::has_use_in_set( Node* n, VectorSet& vset ) {
2678   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2679     Node* use = n->fast_out(j);
2680     if (vset.test(use->_idx)) {
2681       return true;
2682     }
2683   }
2684   return false;
2685 }
2686 
2687 
2688 //------------------------------ has_use_internal_to_set -------------------------------------
2689 // Has use internal to the vector set (ie. not in a phi at the loop head)
2690 bool PhaseIdealLoop::has_use_internal_to_set( Node* n, VectorSet& vset, IdealLoopTree *loop ) {
2691   Node* head  = loop->_head;
2692   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2693     Node* use = n->fast_out(j);
2694     if (vset.test(use->_idx) && !(use->is_Phi() && use->in(0) == head)) {
2695       return true;
2696     }
2697   }
2698   return false;
2699 }
2700 
2701 
2702 //------------------------------ clone_for_use_outside_loop -------------------------------------
2703 // clone "n" for uses that are outside of loop
2704 int PhaseIdealLoop::clone_for_use_outside_loop( IdealLoopTree *loop, Node* n, Node_List& worklist ) {
2705   int cloned = 0;
2706   assert(worklist.size() == 0, "should be empty");
2707   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2708     Node* use = n->fast_out(j);
2709     if( !loop->is_member(get_loop(has_ctrl(use) ? get_ctrl(use) : use)) ) {
2710       worklist.push(use);
2711     }
2712   }
2713   while( worklist.size() ) {
2714     Node *use = worklist.pop();
2715     if (!has_node(use) || use->in(0) == C->top()) continue;
2716     uint j;
2717     for (j = 0; j < use->req(); j++) {
2718       if (use->in(j) == n) break;
2719     }
2720     assert(j < use->req(), "must be there");
2721 
2722     // clone "n" and insert it between the inputs of "n" and the use outside the loop
2723     Node* n_clone = n->clone();
2724     _igvn.replace_input_of(use, j, n_clone);
2725     cloned++;
2726     Node* use_c;
2727     if (!use->is_Phi()) {
2728       use_c = has_ctrl(use) ? get_ctrl(use) : use->in(0);
2729     } else {
2730       // Use in a phi is considered a use in the associated predecessor block
2731       use_c = use->in(0)->in(j);
2732     }
2733     set_ctrl(n_clone, use_c);
2734     assert(!loop->is_member(get_loop(use_c)), "should be outside loop");
2735     get_loop(use_c)->_body.push(n_clone);
2736     _igvn.register_new_node_with_optimizer(n_clone);
2737 #ifndef PRODUCT
2738     if (TracePartialPeeling) {
2739       tty->print_cr("loop exit cloning old: %d new: %d newbb: %d", n->_idx, n_clone->_idx, get_ctrl(n_clone)->_idx);
2740     }
2741 #endif
2742   }
2743   return cloned;
2744 }
2745 
2746 
2747 //------------------------------ clone_for_special_use_inside_loop -------------------------------------
2748 // clone "n" for special uses that are in the not_peeled region.
2749 // If these def-uses occur in separate blocks, the code generator
2750 // marks the method as not compilable.  For example, if a "BoolNode"
2751 // is in a different basic block than the "IfNode" that uses it, then
2752 // the compilation is aborted in the code generator.
2753 void PhaseIdealLoop::clone_for_special_use_inside_loop( IdealLoopTree *loop, Node* n,
2754                                                         VectorSet& not_peel, Node_List& sink_list, Node_List& worklist ) {
2755   if (n->is_Phi() || n->is_Load()) {
2756     return;
2757   }
2758   assert(worklist.size() == 0, "should be empty");
2759   for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
2760     Node* use = n->fast_out(j);
2761     if ( not_peel.test(use->_idx) &&
2762          (use->is_If() || use->is_CMove() || use->is_Bool()) &&
2763          use->in(1) == n)  {
2764       worklist.push(use);
2765     }
2766   }
2767   if (worklist.size() > 0) {
2768     // clone "n" and insert it between inputs of "n" and the use
2769     Node* n_clone = n->clone();
2770     loop->_body.push(n_clone);
2771     _igvn.register_new_node_with_optimizer(n_clone);
2772     set_ctrl(n_clone, get_ctrl(n));
2773     sink_list.push(n_clone);
2774     not_peel.set(n_clone->_idx);
2775 #ifndef PRODUCT
2776     if (TracePartialPeeling) {
2777       tty->print_cr("special not_peeled cloning old: %d new: %d", n->_idx, n_clone->_idx);
2778     }
2779 #endif
2780     while( worklist.size() ) {
2781       Node *use = worklist.pop();
2782       _igvn.rehash_node_delayed(use);
2783       for (uint j = 1; j < use->req(); j++) {
2784         if (use->in(j) == n) {
2785           use->set_req(j, n_clone);
2786         }
2787       }
2788     }
2789   }
2790 }
2791 
2792 
2793 //------------------------------ insert_phi_for_loop -------------------------------------
2794 // Insert phi(lp_entry_val, back_edge_val) at use->in(idx) for loop lp if phi does not already exist
2795 void PhaseIdealLoop::insert_phi_for_loop( Node* use, uint idx, Node* lp_entry_val, Node* back_edge_val, LoopNode* lp ) {
2796   Node *phi = PhiNode::make(lp, back_edge_val);
2797   phi->set_req(LoopNode::EntryControl, lp_entry_val);
2798   // Use existing phi if it already exists
2799   Node *hit = _igvn.hash_find_insert(phi);
2800   if( hit == NULL ) {
2801     _igvn.register_new_node_with_optimizer(phi);
2802     set_ctrl(phi, lp);
2803   } else {
2804     // Remove the new phi from the graph and use the hit
2805     _igvn.remove_dead_node(phi);
2806     phi = hit;
2807   }
2808   _igvn.replace_input_of(use, idx, phi);
2809 }
2810 
2811 #ifdef ASSERT
2812 //------------------------------ is_valid_loop_partition -------------------------------------
2813 // Validate the loop partition sets: peel and not_peel
2814 bool PhaseIdealLoop::is_valid_loop_partition( IdealLoopTree *loop, VectorSet& peel, Node_List& peel_list,
2815                                               VectorSet& not_peel ) {
2816   uint i;
2817   // Check that peel_list entries are in the peel set
2818   for (i = 0; i < peel_list.size(); i++) {
2819     if (!peel.test(peel_list.at(i)->_idx)) {
2820       return false;
2821     }
2822   }
2823   // Check at loop members are in one of peel set or not_peel set
2824   for (i = 0; i < loop->_body.size(); i++ ) {
2825     Node *def  = loop->_body.at(i);
2826     uint di = def->_idx;
2827     // Check that peel set elements are in peel_list
2828     if (peel.test(di)) {
2829       if (not_peel.test(di)) {
2830         return false;
2831       }
2832       // Must be in peel_list also
2833       bool found = false;
2834       for (uint j = 0; j < peel_list.size(); j++) {
2835         if (peel_list.at(j)->_idx == di) {
2836           found = true;
2837           break;
2838         }
2839       }
2840       if (!found) {
2841         return false;
2842       }
2843     } else if (not_peel.test(di)) {
2844       if (peel.test(di)) {
2845         return false;
2846       }
2847     } else {
2848       return false;
2849     }
2850   }
2851   return true;
2852 }
2853 
2854 //------------------------------ is_valid_clone_loop_exit_use -------------------------------------
2855 // Ensure a use outside of loop is of the right form
2856 bool PhaseIdealLoop::is_valid_clone_loop_exit_use( IdealLoopTree *loop, Node* use, uint exit_idx) {
2857   Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2858   return (use->is_Phi() &&
2859           use_c->is_Region() && use_c->req() == 3 &&
2860           (use_c->in(exit_idx)->Opcode() == Op_IfTrue ||
2861            use_c->in(exit_idx)->Opcode() == Op_IfFalse ||
2862            use_c->in(exit_idx)->Opcode() == Op_JumpProj) &&
2863           loop->is_member( get_loop( use_c->in(exit_idx)->in(0) ) ) );
2864 }
2865 
2866 //------------------------------ is_valid_clone_loop_form -------------------------------------
2867 // Ensure that all uses outside of loop are of the right form
2868 bool PhaseIdealLoop::is_valid_clone_loop_form( IdealLoopTree *loop, Node_List& peel_list,
2869                                                uint orig_exit_idx, uint clone_exit_idx) {
2870   uint len = peel_list.size();
2871   for (uint i = 0; i < len; i++) {
2872     Node *def = peel_list.at(i);
2873 
2874     for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
2875       Node *use = def->fast_out(j);
2876       Node *use_c = has_ctrl(use) ? get_ctrl(use) : use;
2877       if (!loop->is_member(get_loop(use_c))) {
2878         // use is not in the loop, check for correct structure
2879         if (use->in(0) == def) {
2880           // Okay
2881         } else if (!is_valid_clone_loop_exit_use(loop, use, orig_exit_idx)) {
2882           return false;
2883         }
2884       }
2885     }
2886   }
2887   return true;
2888 }
2889 #endif
2890 
2891 //------------------------------ partial_peel -------------------------------------
2892 // Partially peel (aka loop rotation) the top portion of a loop (called
2893 // the peel section below) by cloning it and placing one copy just before
2894 // the new loop head and the other copy at the bottom of the new loop.
2895 //
2896 //    before                       after                where it came from
2897 //
2898 //    stmt1                        stmt1
2899 //  loop:                          stmt2                     clone
2900 //    stmt2                        if condA goto exitA       clone
2901 //    if condA goto exitA        new_loop:                   new
2902 //    stmt3                        stmt3                     clone
2903 //    if !condB goto loop          if condB goto exitB       clone
2904 //  exitB:                         stmt2                     orig
2905 //    stmt4                        if !condA goto new_loop   orig
2906 //  exitA:                         goto exitA
2907 //                               exitB:
2908 //                                 stmt4
2909 //                               exitA:
2910 //
2911 // Step 1: find the cut point: an exit test on probable
2912 //         induction variable.
2913 // Step 2: schedule (with cloning) operations in the peel
2914 //         section that can be executed after the cut into
2915 //         the section that is not peeled.  This may need
2916 //         to clone operations into exit blocks.  For
2917 //         instance, a reference to A[i] in the not-peel
2918 //         section and a reference to B[i] in an exit block
2919 //         may cause a left-shift of i by 2 to be placed
2920 //         in the peel block.  This step will clone the left
2921 //         shift into the exit block and sink the left shift
2922 //         from the peel to the not-peel section.
2923 // Step 3: clone the loop, retarget the control, and insert
2924 //         phis for values that are live across the new loop
2925 //         head.  This is very dependent on the graph structure
2926 //         from clone_loop.  It creates region nodes for
2927 //         exit control and associated phi nodes for values
2928 //         flow out of the loop through that exit.  The region
2929 //         node is dominated by the clone's control projection.
2930 //         So the clone's peel section is placed before the
2931 //         new loop head, and the clone's not-peel section is
2932 //         forms the top part of the new loop.  The original
2933 //         peel section forms the tail of the new loop.
2934 // Step 4: update the dominator tree and recompute the
2935 //         dominator depth.
2936 //
2937 //                   orig
2938 //
2939 //                   stmt1
2940 //                     |
2941 //                     v
2942 //               loop predicate
2943 //                     |
2944 //                     v
2945 //                   loop<----+
2946 //                     |      |
2947 //                   stmt2    |
2948 //                     |      |
2949 //                     v      |
2950 //                    ifA     |
2951 //                   / |      |
2952 //                  v  v      |
2953 //               false true   ^  <-- last_peel
2954 //               /     |      |
2955 //              /   ===|==cut |
2956 //             /     stmt3    |  <-- first_not_peel
2957 //            /        |      |
2958 //            |        v      |
2959 //            v       ifB     |
2960 //          exitA:   / \      |
2961 //                  /   \     |
2962 //                 v     v    |
2963 //               false true   |
2964 //               /       \    |
2965 //              /         ----+
2966 //             |
2967 //             v
2968 //           exitB:
2969 //           stmt4
2970 //
2971 //
2972 //            after clone loop
2973 //
2974 //                   stmt1
2975 //                     |
2976 //                     v
2977 //               loop predicate
2978 //                 /       \
2979 //        clone   /         \   orig
2980 //               /           \
2981 //              /             \
2982 //             v               v
2983 //   +---->loop                loop<----+
2984 //   |      |                    |      |
2985 //   |    stmt2                stmt2    |
2986 //   |      |                    |      |
2987 //   |      v                    v      |
2988 //   |      ifA                 ifA     |
2989 //   |      | \                / |      |
2990 //   |      v  v              v  v      |
2991 //   ^    true  false      false true   ^  <-- last_peel
2992 //   |      |   ^   \       /    |      |
2993 //   | cut==|==  \   \     /  ===|==cut |
2994 //   |    stmt3   \   \   /    stmt3    |  <-- first_not_peel
2995 //   |      |    dom   | |       |      |
2996 //   |      v      \  1v v2      v      |
2997 //   |      ifB     regionA     ifB     |
2998 //   |      / \        |       / \      |
2999 //   |     /   \       v      /   \     |
3000 //   |    v     v    exitA:  v     v    |
3001 //   |    true  false      false true   |
3002 //   |    /     ^   \      /       \    |
3003 //   +----       \   \    /         ----+
3004 //               dom  \  /
3005 //                 \  1v v2
3006 //                  regionB
3007 //                     |
3008 //                     v
3009 //                   exitB:
3010 //                   stmt4
3011 //
3012 //
3013 //           after partial peel
3014 //
3015 //                  stmt1
3016 //                     |
3017 //                     v
3018 //               loop predicate
3019 //                 /
3020 //        clone   /             orig
3021 //               /          TOP
3022 //              /             \
3023 //             v               v
3024 //    TOP->loop                loop----+
3025 //          |                    |      |
3026 //        stmt2                stmt2    |
3027 //          |                    |      |
3028 //          v                    v      |
3029 //          ifA                 ifA     |
3030 //          | \                / |      |
3031 //          v  v              v  v      |
3032 //        true  false      false true   |     <-- last_peel
3033 //          |   ^   \       /    +------|---+
3034 //  +->newloop   \   \     /  === ==cut |   |
3035 //  |     stmt3   \   \   /     TOP     |   |
3036 //  |       |    dom   | |      stmt3   |   | <-- first_not_peel
3037 //  |       v      \  1v v2      v      |   |
3038 //  |       ifB     regionA     ifB     ^   v
3039 //  |       / \        |       / \      |   |
3040 //  |      /   \       v      /   \     |   |
3041 //  |     v     v    exitA:  v     v    |   |
3042 //  |     true  false      false true   |   |
3043 //  |     /     ^   \      /       \    |   |
3044 //  |    |       \   \    /         v   |   |
3045 //  |    |       dom  \  /         TOP  |   |
3046 //  |    |         \  1v v2             |   |
3047 //  ^    v          regionB             |   |
3048 //  |    |             |                |   |
3049 //  |    |             v                ^   v
3050 //  |    |           exitB:             |   |
3051 //  |    |           stmt4              |   |
3052 //  |    +------------>-----------------+   |
3053 //  |                                       |
3054 //  +-----------------<---------------------+
3055 //
3056 //
3057 //              final graph
3058 //
3059 //                  stmt1
3060 //                    |
3061 //                    v
3062 //               loop predicate
3063 //                    |
3064 //                    v
3065 //                  stmt2 clone
3066 //                    |
3067 //                    v
3068 //         ........> ifA clone
3069 //         :        / |
3070 //        dom      /  |
3071 //         :      v   v
3072 //         :  false   true
3073 //         :  |       |
3074 //         :  |       v
3075 //         :  |    newloop<-----+
3076 //         :  |        |        |
3077 //         :  |     stmt3 clone |
3078 //         :  |        |        |
3079 //         :  |        v        |
3080 //         :  |       ifB       |
3081 //         :  |      / \        |
3082 //         :  |     v   v       |
3083 //         :  |  false true     |
3084 //         :  |   |     |       |
3085 //         :  |   v    stmt2    |
3086 //         :  | exitB:  |       |
3087 //         :  | stmt4   v       |
3088 //         :  |       ifA orig  |
3089 //         :  |      /  \       |
3090 //         :  |     /    \      |
3091 //         :  |    v     v      |
3092 //         :  |  false  true    |
3093 //         :  |  /        \     |
3094 //         :  v  v         -----+
3095 //          RegionA
3096 //             |
3097 //             v
3098 //           exitA
3099 //
3100 bool PhaseIdealLoop::partial_peel( IdealLoopTree *loop, Node_List &old_new ) {
3101 
3102   assert(!loop->_head->is_CountedLoop(), "Non-counted loop only");
3103   if (!loop->_head->is_Loop()) {
3104     return false;
3105   }
3106   LoopNode *head = loop->_head->as_Loop();
3107 
3108   if (head->is_partial_peel_loop() || head->partial_peel_has_failed()) {
3109     return false;
3110   }
3111 
3112   // Check for complex exit control
3113   for (uint ii = 0; ii < loop->_body.size(); ii++) {
3114     Node *n = loop->_body.at(ii);
3115     int opc = n->Opcode();
3116     if (n->is_Call()        ||
3117         opc == Op_Catch     ||
3118         opc == Op_CatchProj ||
3119         opc == Op_Jump      ||
3120         opc == Op_JumpProj) {
3121 #ifndef PRODUCT
3122       if (TracePartialPeeling) {
3123         tty->print_cr("\nExit control too complex: lp: %d", head->_idx);
3124       }
3125 #endif
3126       return false;
3127     }
3128   }
3129 
3130   int dd = dom_depth(head);
3131 
3132   // Step 1: find cut point
3133 
3134   // Walk up dominators to loop head looking for first loop exit
3135   // which is executed on every path thru loop.
3136   IfNode *peel_if = NULL;
3137   IfNode *peel_if_cmpu = NULL;
3138 
3139   Node *iff = loop->tail();
3140   while (iff != head) {
3141     if (iff->is_If()) {
3142       Node *ctrl = get_ctrl(iff->in(1));
3143       if (ctrl->is_top()) return false; // Dead test on live IF.
3144       // If loop-varying exit-test, check for induction variable
3145       if (loop->is_member(get_loop(ctrl)) &&
3146           loop->is_loop_exit(iff) &&
3147           is_possible_iv_test(iff)) {
3148         Node* cmp = iff->in(1)->in(1);
3149         if (cmp->Opcode() == Op_CmpI) {
3150           peel_if = iff->as_If();
3151         } else {
3152           assert(cmp->Opcode() == Op_CmpU, "must be CmpI or CmpU");
3153           peel_if_cmpu = iff->as_If();
3154         }
3155       }
3156     }
3157     iff = idom(iff);
3158   }
3159 
3160   // Prefer signed compare over unsigned compare.
3161   IfNode* new_peel_if = NULL;
3162   if (peel_if == NULL) {
3163     if (!PartialPeelAtUnsignedTests || peel_if_cmpu == NULL) {
3164       return false;   // No peel point found
3165     }
3166     new_peel_if = insert_cmpi_loop_exit(peel_if_cmpu, loop);
3167     if (new_peel_if == NULL) {
3168       return false;   // No peel point found
3169     }
3170     peel_if = new_peel_if;
3171   }
3172   Node* last_peel        = stay_in_loop(peel_if, loop);
3173   Node* first_not_peeled = stay_in_loop(last_peel, loop);
3174   if (first_not_peeled == NULL || first_not_peeled == head) {
3175     return false;
3176   }
3177 
3178 #ifndef PRODUCT
3179   if (TraceLoopOpts) {
3180     tty->print("PartialPeel  ");
3181     loop->dump_head();
3182   }
3183 
3184   if (TracePartialPeeling) {
3185     tty->print_cr("before partial peel one iteration");
3186     Node_List wl;
3187     Node* t = head->in(2);
3188     while (true) {
3189       wl.push(t);
3190       if (t == head) break;
3191       t = idom(t);
3192     }
3193     while (wl.size() > 0) {
3194       Node* tt = wl.pop();
3195       tt->dump();
3196       if (tt == last_peel) tty->print_cr("-- cut --");
3197     }
3198   }
3199 #endif
3200   VectorSet peel;
3201   VectorSet not_peel;
3202   Node_List peel_list;
3203   Node_List worklist;
3204   Node_List sink_list;
3205 
3206   uint estimate = loop->est_loop_clone_sz(1);
3207   if (exceeding_node_budget(estimate)) {
3208     return false;
3209   }
3210 
3211   // Set of cfg nodes to peel are those that are executable from
3212   // the head through last_peel.
3213   assert(worklist.size() == 0, "should be empty");
3214   worklist.push(head);
3215   peel.set(head->_idx);
3216   while (worklist.size() > 0) {
3217     Node *n = worklist.pop();
3218     if (n != last_peel) {
3219       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
3220         Node* use = n->fast_out(j);
3221         if (use->is_CFG() &&
3222             loop->is_member(get_loop(use)) &&
3223             !peel.test_set(use->_idx)) {
3224           worklist.push(use);
3225         }
3226       }
3227     }
3228   }
3229 
3230   // Set of non-cfg nodes to peel are those that are control
3231   // dependent on the cfg nodes.
3232   for (uint i = 0; i < loop->_body.size(); i++) {
3233     Node *n = loop->_body.at(i);
3234     Node *n_c = has_ctrl(n) ? get_ctrl(n) : n;
3235     if (peel.test(n_c->_idx)) {
3236       peel.set(n->_idx);
3237     } else {
3238       not_peel.set(n->_idx);
3239     }
3240   }
3241 
3242   // Step 2: move operations from the peeled section down into the
3243   //         not-peeled section
3244 
3245   // Get a post order schedule of nodes in the peel region
3246   // Result in right-most operand.
3247   scheduled_nodelist(loop, peel, peel_list);
3248 
3249   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3250 
3251   // For future check for too many new phis
3252   uint old_phi_cnt = 0;
3253   for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
3254     Node* use = head->fast_out(j);
3255     if (use->is_Phi()) old_phi_cnt++;
3256   }
3257 
3258 #ifndef PRODUCT
3259   if (TracePartialPeeling) {
3260     tty->print_cr("\npeeled list");
3261   }
3262 #endif
3263 
3264   // Evacuate nodes in peel region into the not_peeled region if possible
3265   uint new_phi_cnt = 0;
3266   uint cloned_for_outside_use = 0;
3267   for (uint i = 0; i < peel_list.size();) {
3268     Node* n = peel_list.at(i);
3269 #ifndef PRODUCT
3270   if (TracePartialPeeling) n->dump();
3271 #endif
3272     bool incr = true;
3273     if (!n->is_CFG()) {
3274       if (has_use_in_set(n, not_peel)) {
3275         // If not used internal to the peeled region,
3276         // move "n" from peeled to not_peeled region.
3277         if (!has_use_internal_to_set(n, peel, loop)) {
3278           // if not pinned and not a load (which maybe anti-dependent on a store)
3279           // and not a CMove (Matcher expects only bool->cmove).
3280           if (n->in(0) == NULL && !n->is_Load() && !n->is_CMove()) {
3281             cloned_for_outside_use += clone_for_use_outside_loop(loop, n, worklist);
3282             sink_list.push(n);
3283             peel.remove(n->_idx);
3284             not_peel.set(n->_idx);
3285             peel_list.remove(i);
3286             incr = false;
3287 #ifndef PRODUCT
3288             if (TracePartialPeeling) {
3289               tty->print_cr("sink to not_peeled region: %d newbb: %d",
3290                             n->_idx, get_ctrl(n)->_idx);
3291             }
3292 #endif
3293           }
3294         } else {
3295           // Otherwise check for special def-use cases that span
3296           // the peel/not_peel boundary such as bool->if
3297           clone_for_special_use_inside_loop(loop, n, not_peel, sink_list, worklist);
3298           new_phi_cnt++;
3299         }
3300       }
3301     }
3302     if (incr) i++;
3303   }
3304 
3305   estimate += cloned_for_outside_use + new_phi_cnt;
3306   bool exceed_node_budget = !may_require_nodes(estimate);
3307   bool exceed_phi_limit = new_phi_cnt > old_phi_cnt + PartialPeelNewPhiDelta;
3308 
3309   if (exceed_node_budget || exceed_phi_limit) {
3310 #ifndef PRODUCT
3311     if (TracePartialPeeling) {
3312       tty->print_cr("\nToo many new phis: %d  old %d new cmpi: %c",
3313                     new_phi_cnt, old_phi_cnt, new_peel_if != NULL?'T':'F');
3314     }
3315 #endif
3316     if (new_peel_if != NULL) {
3317       remove_cmpi_loop_exit(new_peel_if, loop);
3318     }
3319     // Inhibit more partial peeling on this loop
3320     assert(!head->is_partial_peel_loop(), "not partial peeled");
3321     head->mark_partial_peel_failed();
3322     if (cloned_for_outside_use > 0) {
3323       // Terminate this round of loop opts because
3324       // the graph outside this loop was changed.
3325       C->set_major_progress();
3326       return true;
3327     }
3328     return false;
3329   }
3330 
3331   // Step 3: clone loop, retarget control, and insert new phis
3332 
3333   // Create new loop head for new phis and to hang
3334   // the nodes being moved (sinked) from the peel region.
3335   LoopNode* new_head = new LoopNode(last_peel, last_peel);
3336   new_head->set_unswitch_count(head->unswitch_count()); // Preserve
3337   _igvn.register_new_node_with_optimizer(new_head);
3338   assert(first_not_peeled->in(0) == last_peel, "last_peel <- first_not_peeled");
3339   _igvn.replace_input_of(first_not_peeled, 0, new_head);
3340   set_loop(new_head, loop);
3341   loop->_body.push(new_head);
3342   not_peel.set(new_head->_idx);
3343   set_idom(new_head, last_peel, dom_depth(first_not_peeled));
3344   set_idom(first_not_peeled, new_head, dom_depth(first_not_peeled));
3345 
3346   while (sink_list.size() > 0) {
3347     Node* n = sink_list.pop();
3348     set_ctrl(n, new_head);
3349   }
3350 
3351   assert(is_valid_loop_partition(loop, peel, peel_list, not_peel), "bad partition");
3352 
3353   clone_loop(loop, old_new, dd, IgnoreStripMined);
3354 
3355   const uint clone_exit_idx = 1;
3356   const uint orig_exit_idx  = 2;
3357   assert(is_valid_clone_loop_form(loop, peel_list, orig_exit_idx, clone_exit_idx), "bad clone loop");
3358 
3359   Node* head_clone             = old_new[head->_idx];
3360   LoopNode* new_head_clone     = old_new[new_head->_idx]->as_Loop();
3361   Node* orig_tail_clone        = head_clone->in(2);
3362 
3363   // Add phi if "def" node is in peel set and "use" is not
3364 
3365   for (uint i = 0; i < peel_list.size(); i++) {
3366     Node *def  = peel_list.at(i);
3367     if (!def->is_CFG()) {
3368       for (DUIterator_Fast jmax, j = def->fast_outs(jmax); j < jmax; j++) {
3369         Node *use = def->fast_out(j);
3370         if (has_node(use) && use->in(0) != C->top() &&
3371             (!peel.test(use->_idx) ||
3372              (use->is_Phi() && use->in(0) == head)) ) {
3373           worklist.push(use);
3374         }
3375       }
3376       while( worklist.size() ) {
3377         Node *use = worklist.pop();
3378         for (uint j = 1; j < use->req(); j++) {
3379           Node* n = use->in(j);
3380           if (n == def) {
3381 
3382             // "def" is in peel set, "use" is not in peel set
3383             // or "use" is in the entry boundary (a phi) of the peel set
3384 
3385             Node* use_c = has_ctrl(use) ? get_ctrl(use) : use;
3386 
3387             if ( loop->is_member(get_loop( use_c )) ) {
3388               // use is in loop
3389               if (old_new[use->_idx] != NULL) { // null for dead code
3390                 Node* use_clone = old_new[use->_idx];
3391                 _igvn.replace_input_of(use, j, C->top());
3392                 insert_phi_for_loop( use_clone, j, old_new[def->_idx], def, new_head_clone );
3393               }
3394             } else {
3395               assert(is_valid_clone_loop_exit_use(loop, use, orig_exit_idx), "clone loop format");
3396               // use is not in the loop, check if the live range includes the cut
3397               Node* lp_if = use_c->in(orig_exit_idx)->in(0);
3398               if (not_peel.test(lp_if->_idx)) {
3399                 assert(j == orig_exit_idx, "use from original loop");
3400                 insert_phi_for_loop( use, clone_exit_idx, old_new[def->_idx], def, new_head_clone );
3401               }
3402             }
3403           }
3404         }
3405       }
3406     }
3407   }
3408 
3409   // Step 3b: retarget control
3410 
3411   // Redirect control to the new loop head if a cloned node in
3412   // the not_peeled region has control that points into the peeled region.
3413   // This necessary because the cloned peeled region will be outside
3414   // the loop.
3415   //                            from    to
3416   //          cloned-peeled    <---+
3417   //    new_head_clone:            |    <--+
3418   //          cloned-not_peeled  in(0)    in(0)
3419   //          orig-peeled
3420 
3421   for (uint i = 0; i < loop->_body.size(); i++) {
3422     Node *n = loop->_body.at(i);
3423     if (!n->is_CFG()           && n->in(0) != NULL        &&
3424         not_peel.test(n->_idx) && peel.test(n->in(0)->_idx)) {
3425       Node* n_clone = old_new[n->_idx];
3426       _igvn.replace_input_of(n_clone, 0, new_head_clone);
3427     }
3428   }
3429 
3430   // Backedge of the surviving new_head (the clone) is original last_peel
3431   _igvn.replace_input_of(new_head_clone, LoopNode::LoopBackControl, last_peel);
3432 
3433   // Cut first node in original not_peel set
3434   _igvn.rehash_node_delayed(new_head);                     // Multiple edge updates:
3435   new_head->set_req(LoopNode::EntryControl,    C->top());  //   use rehash_node_delayed / set_req instead of
3436   new_head->set_req(LoopNode::LoopBackControl, C->top());  //   multiple replace_input_of calls
3437 
3438   // Copy head_clone back-branch info to original head
3439   // and remove original head's loop entry and
3440   // clone head's back-branch
3441   _igvn.rehash_node_delayed(head); // Multiple edge updates
3442   head->set_req(LoopNode::EntryControl,    head_clone->in(LoopNode::LoopBackControl));
3443   head->set_req(LoopNode::LoopBackControl, C->top());
3444   _igvn.replace_input_of(head_clone, LoopNode::LoopBackControl, C->top());
3445 
3446   // Similarly modify the phis
3447   for (DUIterator_Fast kmax, k = head->fast_outs(kmax); k < kmax; k++) {
3448     Node* use = head->fast_out(k);
3449     if (use->is_Phi() && use->outcnt() > 0) {
3450       Node* use_clone = old_new[use->_idx];
3451       _igvn.rehash_node_delayed(use); // Multiple edge updates
3452       use->set_req(LoopNode::EntryControl,    use_clone->in(LoopNode::LoopBackControl));
3453       use->set_req(LoopNode::LoopBackControl, C->top());
3454       _igvn.replace_input_of(use_clone, LoopNode::LoopBackControl, C->top());
3455     }
3456   }
3457 
3458   // Step 4: update dominator tree and dominator depth
3459 
3460   set_idom(head, orig_tail_clone, dd);
3461   recompute_dom_depth();
3462 
3463   // Inhibit more partial peeling on this loop
3464   new_head_clone->set_partial_peel_loop();
3465   C->set_major_progress();
3466   loop->record_for_igvn();
3467 
3468 #ifndef PRODUCT
3469   if (TracePartialPeeling) {
3470     tty->print_cr("\nafter partial peel one iteration");
3471     Node_List wl;
3472     Node* t = last_peel;
3473     while (true) {
3474       wl.push(t);
3475       if (t == head_clone) break;
3476       t = idom(t);
3477     }
3478     while (wl.size() > 0) {
3479       Node* tt = wl.pop();
3480       if (tt == head) tty->print_cr("orig head");
3481       else if (tt == new_head_clone) tty->print_cr("new head");
3482       else if (tt == head_clone) tty->print_cr("clone head");
3483       tt->dump();
3484     }
3485   }
3486 #endif
3487   return true;
3488 }
3489 
3490 //------------------------------reorg_offsets----------------------------------
3491 // Reorganize offset computations to lower register pressure.  Mostly
3492 // prevent loop-fallout uses of the pre-incremented trip counter (which are
3493 // then alive with the post-incremented trip counter forcing an extra
3494 // register move)
3495 void PhaseIdealLoop::reorg_offsets(IdealLoopTree *loop) {
3496   // Perform it only for canonical counted loops.
3497   // Loop's shape could be messed up by iteration_split_impl.
3498   if (!loop->_head->is_CountedLoop())
3499     return;
3500   if (!loop->_head->as_Loop()->is_valid_counted_loop())
3501     return;
3502 
3503   CountedLoopNode *cl = loop->_head->as_CountedLoop();
3504   CountedLoopEndNode *cle = cl->loopexit();
3505   Node *exit = cle->proj_out(false);
3506   Node *phi = cl->phi();
3507 
3508   // Check for the special case when using the pre-incremented trip-counter on
3509   // the fall-out  path (forces the pre-incremented  and post-incremented trip
3510   // counter to be live  at the same time).  Fix this by  adjusting to use the
3511   // post-increment trip counter.
3512 
3513   bool progress = true;
3514   while (progress) {
3515     progress = false;
3516     for (DUIterator_Fast imax, i = phi->fast_outs(imax); i < imax; i++) {
3517       Node* use = phi->fast_out(i);   // User of trip-counter
3518       if (!has_ctrl(use))  continue;
3519       Node *u_ctrl = get_ctrl(use);
3520       if (use->is_Phi()) {
3521         u_ctrl = NULL;
3522         for (uint j = 1; j < use->req(); j++)
3523           if (use->in(j) == phi)
3524             u_ctrl = dom_lca(u_ctrl, use->in(0)->in(j));
3525       }
3526       IdealLoopTree *u_loop = get_loop(u_ctrl);
3527       // Look for loop-invariant use
3528       if (u_loop == loop) continue;
3529       if (loop->is_member(u_loop)) continue;
3530       // Check that use is live out the bottom.  Assuming the trip-counter
3531       // update is right at the bottom, uses of of the loop middle are ok.
3532       if (dom_lca(exit, u_ctrl) != exit) continue;
3533       // Hit!  Refactor use to use the post-incremented tripcounter.
3534       // Compute a post-increment tripcounter.
3535       Node* c = exit;
3536       if (cl->is_strip_mined()) {
3537         IdealLoopTree* outer_loop = get_loop(cl->outer_loop());
3538         if (!outer_loop->is_member(u_loop)) {
3539           c = cl->outer_loop_exit();
3540         }
3541       }
3542       Node *opaq = new Opaque2Node(C, cle->incr());
3543       register_new_node(opaq, c);
3544       Node *neg_stride = _igvn.intcon(-cle->stride_con());
3545       set_ctrl(neg_stride, C->root());
3546       Node *post = new AddINode(opaq, neg_stride);
3547       register_new_node(post, c);
3548       _igvn.rehash_node_delayed(use);
3549       for (uint j = 1; j < use->req(); j++) {
3550         if (use->in(j) == phi)
3551           use->set_req(j, post);
3552       }
3553       // Since DU info changed, rerun loop
3554       progress = true;
3555       break;
3556     }
3557   }
3558 
3559 }
--- EOF ---