1 /*
   2  * Copyright (c) 2000, 2015, 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 "ci/ciTypeFlow.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "opto/addnode.hpp"
  29 #include "opto/castnode.hpp"
  30 #include "opto/cfgnode.hpp"
  31 #include "opto/connode.hpp"
  32 #include "opto/loopnode.hpp"
  33 #include "opto/phaseX.hpp"
  34 #include "opto/runtime.hpp"
  35 #include "opto/rootnode.hpp"
  36 #include "opto/subnode.hpp"
  37 
  38 // Portions of code courtesy of Clifford Click
  39 
  40 // Optimization - Graph Style
  41 
  42 
  43 extern int explicit_null_checks_elided;
  44 
  45 //=============================================================================
  46 //------------------------------Value------------------------------------------
  47 // Return a tuple for whichever arm of the IF is reachable
  48 const Type *IfNode::Value( PhaseTransform *phase ) const {
  49   if( !in(0) ) return Type::TOP;
  50   if( phase->type(in(0)) == Type::TOP )
  51     return Type::TOP;
  52   const Type *t = phase->type(in(1));
  53   if( t == Type::TOP )          // data is undefined
  54     return TypeTuple::IFNEITHER; // unreachable altogether
  55   if( t == TypeInt::ZERO )      // zero, or false
  56     return TypeTuple::IFFALSE;  // only false branch is reachable
  57   if( t == TypeInt::ONE )       // 1, or true
  58     return TypeTuple::IFTRUE;   // only true branch is reachable
  59   assert( t == TypeInt::BOOL, "expected boolean type" );
  60 
  61   return TypeTuple::IFBOTH;     // No progress
  62 }
  63 
  64 const RegMask &IfNode::out_RegMask() const {
  65   return RegMask::Empty;
  66 }
  67 
  68 //------------------------------split_if---------------------------------------
  69 // Look for places where we merge constants, then test on the merged value.
  70 // If the IF test will be constant folded on the path with the constant, we
  71 // win by splitting the IF to before the merge point.
  72 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
  73   // I could be a lot more general here, but I'm trying to squeeze this
  74   // in before the Christmas '98 break so I'm gonna be kinda restrictive
  75   // on the patterns I accept.  CNC
  76 
  77   // Look for a compare of a constant and a merged value
  78   Node *i1 = iff->in(1);
  79   if( !i1->is_Bool() ) return NULL;
  80   BoolNode *b = i1->as_Bool();
  81   Node *cmp = b->in(1);
  82   if( !cmp->is_Cmp() ) return NULL;
  83   i1 = cmp->in(1);
  84   if( i1 == NULL || !i1->is_Phi() ) return NULL;
  85   PhiNode *phi = i1->as_Phi();
  86   if( phi->is_copy() ) return NULL;
  87   Node *con2 = cmp->in(2);
  88   if( !con2->is_Con() ) return NULL;
  89   // See that the merge point contains some constants
  90   Node *con1=NULL;
  91   uint i4;
  92   for( i4 = 1; i4 < phi->req(); i4++ ) {
  93     con1 = phi->in(i4);
  94     if( !con1 ) return NULL;    // Do not optimize partially collapsed merges
  95     if( con1->is_Con() ) break; // Found a constant
  96     // Also allow null-vs-not-null checks
  97     const TypePtr *tp = igvn->type(con1)->isa_ptr();
  98     if( tp && tp->_ptr == TypePtr::NotNull )
  99       break;
 100   }
 101   if( i4 >= phi->req() ) return NULL; // Found no constants
 102 
 103   igvn->C->set_has_split_ifs(true); // Has chance for split-if
 104 
 105   // Make sure that the compare can be constant folded away
 106   Node *cmp2 = cmp->clone();
 107   cmp2->set_req(1,con1);
 108   cmp2->set_req(2,con2);
 109   const Type *t = cmp2->Value(igvn);
 110   // This compare is dead, so whack it!
 111   igvn->remove_dead_node(cmp2);
 112   if( !t->singleton() ) return NULL;
 113 
 114   // No intervening control, like a simple Call
 115   Node *r = iff->in(0);
 116   if( !r->is_Region() ) return NULL;
 117   if( phi->region() != r ) return NULL;
 118   // No other users of the cmp/bool
 119   if (b->outcnt() != 1 || cmp->outcnt() != 1) {
 120     //tty->print_cr("many users of cmp/bool");
 121     return NULL;
 122   }
 123 
 124   // Make sure we can determine where all the uses of merged values go
 125   for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {
 126     Node* u = r->fast_out(j);
 127     if( u == r ) continue;
 128     if( u == iff ) continue;
 129     if( u->outcnt() == 0 ) continue; // use is dead & ignorable
 130     if( !u->is_Phi() ) {
 131       /*
 132       if( u->is_Start() ) {
 133         tty->print_cr("Region has inlined start use");
 134       } else {
 135         tty->print_cr("Region has odd use");
 136         u->dump(2);
 137       }*/
 138       return NULL;
 139     }
 140     if( u != phi ) {
 141       // CNC - do not allow any other merged value
 142       //tty->print_cr("Merging another value");
 143       //u->dump(2);
 144       return NULL;
 145     }
 146     // Make sure we can account for all Phi uses
 147     for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) {
 148       Node* v = u->fast_out(k); // User of the phi
 149       // CNC - Allow only really simple patterns.
 150       // In particular I disallow AddP of the Phi, a fairly common pattern
 151       if (v == cmp) continue;  // The compare is OK
 152       if (v->is_ConstraintCast()) {
 153         // If the cast is derived from data flow edges, it may not have a control edge.
 154         // If so, it should be safe to split. But follow-up code can not deal with
 155         // this (l. 359). So skip.
 156         if (v->in(0) == NULL) {
 157           return NULL;
 158         }
 159         if (v->in(0)->in(0) == iff) {
 160           continue;               // CastPP/II of the IfNode is OK
 161         }
 162       }
 163       // Disabled following code because I cannot tell if exactly one
 164       // path dominates without a real dominator check. CNC 9/9/1999
 165       //uint vop = v->Opcode();
 166       //if( vop == Op_Phi ) {     // Phi from another merge point might be OK
 167       //  Node *r = v->in(0);     // Get controlling point
 168       //  if( !r ) return NULL;   // Degraded to a copy
 169       //  // Find exactly one path in (either True or False doms, but not IFF)
 170       //  int cnt = 0;
 171       //  for( uint i = 1; i < r->req(); i++ )
 172       //    if( r->in(i) && r->in(i)->in(0) == iff )
 173       //      cnt++;
 174       //  if( cnt == 1 ) continue; // Exactly one of True or False guards Phi
 175       //}
 176       if( !v->is_Call() ) {
 177         /*
 178         if( v->Opcode() == Op_AddP ) {
 179           tty->print_cr("Phi has AddP use");
 180         } else if( v->Opcode() == Op_CastPP ) {
 181           tty->print_cr("Phi has CastPP use");
 182         } else if( v->Opcode() == Op_CastII ) {
 183           tty->print_cr("Phi has CastII use");
 184         } else {
 185           tty->print_cr("Phi has use I cant be bothered with");
 186         }
 187         */
 188       }
 189       return NULL;
 190 
 191       /* CNC - Cut out all the fancy acceptance tests
 192       // Can we clone this use when doing the transformation?
 193       // If all uses are from Phis at this merge or constants, then YES.
 194       if( !v->in(0) && v != cmp ) {
 195         tty->print_cr("Phi has free-floating use");
 196         v->dump(2);
 197         return NULL;
 198       }
 199       for( uint l = 1; l < v->req(); l++ ) {
 200         if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) &&
 201             !v->in(l)->is_Con() ) {
 202           tty->print_cr("Phi has use");
 203           v->dump(2);
 204           return NULL;
 205         } // End of if Phi-use input is neither Phi nor Constant
 206       } // End of for all inputs to Phi-use
 207       */
 208     } // End of for all uses of Phi
 209   } // End of for all uses of Region
 210 
 211   // Only do this if the IF node is in a sane state
 212   if (iff->outcnt() != 2)
 213     return NULL;
 214 
 215   // Got a hit!  Do the Mondo Hack!
 216   //
 217   //ABC  a1c   def   ghi            B     1     e     h   A C   a c   d f   g i
 218   // R - Phi - Phi - Phi            Rc - Phi - Phi - Phi   Rx - Phi - Phi - Phi
 219   //     cmp - 2                         cmp - 2               cmp - 2
 220   //       bool                            bool_c                bool_x
 221   //       if                               if_c                  if_x
 222   //      T  F                              T  F                  T  F
 223   // ..s..    ..t ..                   ..s..    ..t..        ..s..    ..t..
 224   //
 225   // Split the paths coming into the merge point into 2 separate groups of
 226   // merges.  On the left will be all the paths feeding constants into the
 227   // Cmp's Phi.  On the right will be the remaining paths.  The Cmp's Phi
 228   // will fold up into a constant; this will let the Cmp fold up as well as
 229   // all the control flow.  Below the original IF we have 2 control
 230   // dependent regions, 's' and 't'.  Now we will merge the two paths
 231   // just prior to 's' and 't' from the two IFs.  At least 1 path (and quite
 232   // likely 2 or more) will promptly constant fold away.
 233   PhaseGVN *phase = igvn;
 234 
 235   // Make a region merging constants and a region merging the rest
 236   uint req_c = 0;
 237   Node* predicate_proj = NULL;
 238   int nb_predicate_proj = 0;
 239   for (uint ii = 1; ii < r->req(); ii++) {
 240     if (phi->in(ii) == con1) {
 241       req_c++;
 242     }
 243     Node* proj = PhaseIdealLoop::find_predicate(r->in(ii));
 244     if (proj != NULL) {
 245       nb_predicate_proj++;
 246       predicate_proj = proj;
 247     }
 248   }
 249   if (nb_predicate_proj > 1) {
 250     // Can happen in case of loop unswitching and when the loop is
 251     // optimized out: it's not a loop anymore so we don't care about
 252     // predicates.
 253     assert(!r->is_Loop(), "this must not be a loop anymore");
 254     predicate_proj = NULL;
 255   }
 256   Node* predicate_c = NULL;
 257   Node* predicate_x = NULL;
 258   bool counted_loop = r->is_CountedLoop();
 259 
 260   Node *region_c = new RegionNode(req_c + 1);
 261   Node *phi_c    = con1;
 262   uint  len      = r->req();
 263   Node *region_x = new RegionNode(len - req_c);
 264   Node *phi_x    = PhiNode::make_blank(region_x, phi);
 265   for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
 266     if (phi->in(i) == con1) {
 267       region_c->init_req( i_c++, r  ->in(i) );
 268       if (r->in(i) == predicate_proj)
 269         predicate_c = predicate_proj;
 270     } else {
 271       region_x->init_req( i_x,   r  ->in(i) );
 272       phi_x   ->init_req( i_x++, phi->in(i) );
 273       if (r->in(i) == predicate_proj)
 274         predicate_x = predicate_proj;
 275     }
 276   }
 277   if (predicate_c != NULL && (req_c > 1)) {
 278     assert(predicate_x == NULL, "only one predicate entry expected");
 279     predicate_c = NULL; // Do not clone predicate below merge point
 280   }
 281   if (predicate_x != NULL && ((len - req_c) > 2)) {
 282     assert(predicate_c == NULL, "only one predicate entry expected");
 283     predicate_x = NULL; // Do not clone predicate below merge point
 284   }
 285 
 286   // Register the new RegionNodes but do not transform them.  Cannot
 287   // transform until the entire Region/Phi conglomerate has been hacked
 288   // as a single huge transform.
 289   igvn->register_new_node_with_optimizer( region_c );
 290   igvn->register_new_node_with_optimizer( region_x );
 291   // Prevent the untimely death of phi_x.  Currently he has no uses.  He is
 292   // about to get one.  If this only use goes away, then phi_x will look dead.
 293   // However, he will be picking up some more uses down below.
 294   Node *hook = new Node(4);
 295   hook->init_req(0, phi_x);
 296   hook->init_req(1, phi_c);
 297   phi_x = phase->transform( phi_x );
 298 
 299   // Make the compare
 300   Node *cmp_c = phase->makecon(t);
 301   Node *cmp_x = cmp->clone();
 302   cmp_x->set_req(1,phi_x);
 303   cmp_x->set_req(2,con2);
 304   cmp_x = phase->transform(cmp_x);
 305   // Make the bool
 306   Node *b_c = phase->transform(new BoolNode(cmp_c,b->_test._test));
 307   Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test));
 308   // Make the IfNode
 309   IfNode *iff_c = new IfNode(region_c,b_c,iff->_prob,iff->_fcnt);
 310   igvn->set_type_bottom(iff_c);
 311   igvn->_worklist.push(iff_c);
 312   hook->init_req(2, iff_c);
 313 
 314   IfNode *iff_x = new IfNode(region_x,b_x,iff->_prob, iff->_fcnt);
 315   igvn->set_type_bottom(iff_x);
 316   igvn->_worklist.push(iff_x);
 317   hook->init_req(3, iff_x);
 318 
 319   // Make the true/false arms
 320   Node *iff_c_t = phase->transform(new IfTrueNode (iff_c));
 321   Node *iff_c_f = phase->transform(new IfFalseNode(iff_c));
 322   if (predicate_c != NULL) {
 323     assert(predicate_x == NULL, "only one predicate entry expected");
 324     // Clone loop predicates to each path
 325     iff_c_t = igvn->clone_loop_predicates(predicate_c, iff_c_t, !counted_loop);
 326     iff_c_f = igvn->clone_loop_predicates(predicate_c, iff_c_f, !counted_loop);
 327   }
 328   Node *iff_x_t = phase->transform(new IfTrueNode (iff_x));
 329   Node *iff_x_f = phase->transform(new IfFalseNode(iff_x));
 330   if (predicate_x != NULL) {
 331     assert(predicate_c == NULL, "only one predicate entry expected");
 332     // Clone loop predicates to each path
 333     iff_x_t = igvn->clone_loop_predicates(predicate_x, iff_x_t, !counted_loop);
 334     iff_x_f = igvn->clone_loop_predicates(predicate_x, iff_x_f, !counted_loop);
 335   }
 336 
 337   // Merge the TRUE paths
 338   Node *region_s = new RegionNode(3);
 339   igvn->_worklist.push(region_s);
 340   region_s->init_req(1, iff_c_t);
 341   region_s->init_req(2, iff_x_t);
 342   igvn->register_new_node_with_optimizer( region_s );
 343 
 344   // Merge the FALSE paths
 345   Node *region_f = new RegionNode(3);
 346   igvn->_worklist.push(region_f);
 347   region_f->init_req(1, iff_c_f);
 348   region_f->init_req(2, iff_x_f);
 349   igvn->register_new_node_with_optimizer( region_f );
 350 
 351   igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
 352   cmp->set_req(1,NULL);  // Whack the inputs to cmp because it will be dead
 353   cmp->set_req(2,NULL);
 354   // Check for all uses of the Phi and give them a new home.
 355   // The 'cmp' got cloned, but CastPP/IIs need to be moved.
 356   Node *phi_s = NULL;     // do not construct unless needed
 357   Node *phi_f = NULL;     // do not construct unless needed
 358   for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {
 359     Node* v = phi->last_out(i2);// User of the phi
 360     igvn->rehash_node_delayed(v); // Have to fixup other Phi users
 361     uint vop = v->Opcode();
 362     Node *proj = NULL;
 363     if( vop == Op_Phi ) {       // Remote merge point
 364       Node *r = v->in(0);
 365       for (uint i3 = 1; i3 < r->req(); i3++)
 366         if (r->in(i3) && r->in(i3)->in(0) == iff) {
 367           proj = r->in(i3);
 368           break;
 369         }
 370     } else if( v->is_ConstraintCast() ) {
 371       proj = v->in(0);          // Controlling projection
 372     } else {
 373       assert( 0, "do not know how to handle this guy" );
 374     }
 375 
 376     Node *proj_path_data, *proj_path_ctrl;
 377     if( proj->Opcode() == Op_IfTrue ) {
 378       if( phi_s == NULL ) {
 379         // Only construct phi_s if needed, otherwise provides
 380         // interfering use.
 381         phi_s = PhiNode::make_blank(region_s,phi);
 382         phi_s->init_req( 1, phi_c );
 383         phi_s->init_req( 2, phi_x );
 384         hook->add_req(phi_s);
 385         phi_s = phase->transform(phi_s);
 386       }
 387       proj_path_data = phi_s;
 388       proj_path_ctrl = region_s;
 389     } else {
 390       if( phi_f == NULL ) {
 391         // Only construct phi_f if needed, otherwise provides
 392         // interfering use.
 393         phi_f = PhiNode::make_blank(region_f,phi);
 394         phi_f->init_req( 1, phi_c );
 395         phi_f->init_req( 2, phi_x );
 396         hook->add_req(phi_f);
 397         phi_f = phase->transform(phi_f);
 398       }
 399       proj_path_data = phi_f;
 400       proj_path_ctrl = region_f;
 401     }
 402 
 403     // Fixup 'v' for for the split
 404     if( vop == Op_Phi ) {       // Remote merge point
 405       uint i;
 406       for( i = 1; i < v->req(); i++ )
 407         if( v->in(i) == phi )
 408           break;
 409       v->set_req(i, proj_path_data );
 410     } else if( v->is_ConstraintCast() ) {
 411       v->set_req(0, proj_path_ctrl );
 412       v->set_req(1, proj_path_data );
 413     } else
 414       ShouldNotReachHere();
 415   }
 416 
 417   // Now replace the original iff's True/False with region_s/region_t.
 418   // This makes the original iff go dead.
 419   for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {
 420     Node* p = iff->last_out(i3);
 421     assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
 422     Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
 423     // Replace p with u
 424     igvn->add_users_to_worklist(p);
 425     for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {
 426       Node* x = p->last_out(l);
 427       igvn->hash_delete(x);
 428       uint uses_found = 0;
 429       for( uint j = 0; j < x->req(); j++ ) {
 430         if( x->in(j) == p ) {
 431           x->set_req(j, u);
 432           uses_found++;
 433         }
 434       }
 435       l -= uses_found;    // we deleted 1 or more copies of this edge
 436     }
 437     igvn->remove_dead_node(p);
 438   }
 439 
 440   // Force the original merge dead
 441   igvn->hash_delete(r);
 442   // First, remove region's dead users.
 443   for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {
 444     Node* u = r->last_out(l);
 445     if( u == r ) {
 446       r->set_req(0, NULL);
 447     } else {
 448       assert(u->outcnt() == 0, "only dead users");
 449       igvn->remove_dead_node(u);
 450     }
 451     l -= 1;
 452   }
 453   igvn->remove_dead_node(r);
 454 
 455   // Now remove the bogus extra edges used to keep things alive
 456   igvn->remove_dead_node( hook );
 457 
 458   // Must return either the original node (now dead) or a new node
 459   // (Do not return a top here, since that would break the uniqueness of top.)
 460   return new ConINode(TypeInt::ZERO);
 461 }
 462 
 463 // if this IfNode follows a range check pattern return the projection
 464 // for the failed path
 465 ProjNode* IfNode::range_check_trap_proj(int& flip_test, Node*& l, Node*& r) {
 466   Node* b = in(1);
 467   if (b == NULL || !b->is_Bool())  return NULL;
 468   BoolNode* bn = b->as_Bool();
 469   Node* cmp = bn->in(1);
 470   if (cmp == NULL)  return NULL;
 471   if (cmp->Opcode() != Op_CmpU)  return NULL;
 472 
 473   l = cmp->in(1);
 474   r = cmp->in(2);
 475   flip_test = 1;
 476   if (bn->_test._test == BoolTest::le) {
 477     l = cmp->in(2);
 478     r = cmp->in(1);
 479     flip_test = 2;
 480   } else if (bn->_test._test != BoolTest::lt) {
 481     return NULL;
 482   }
 483   if (l->is_top())  return NULL;   // Top input means dead test
 484   if (r->Opcode() != Op_LoadRange)  return NULL;
 485 
 486   // We have recognized one of these forms:
 487   //  Flip 1:  If (Bool[<] CmpU(l, LoadRange)) ...
 488   //  Flip 2:  If (Bool[<=] CmpU(LoadRange, l)) ...
 489 
 490   ProjNode* iftrap = proj_out(flip_test == 2 ? true : false);
 491   return iftrap;
 492 }
 493 
 494 
 495 //------------------------------is_range_check---------------------------------
 496 // Return 0 if not a range check.  Return 1 if a range check and set index and
 497 // offset.  Return 2 if we had to negate the test.  Index is NULL if the check
 498 // is versus a constant.
 499 int IfNode::is_range_check(Node* &range, Node* &index, jint &offset) {
 500   int flip_test = 0;
 501   Node* l = NULL;
 502   Node* r = NULL;
 503   ProjNode* iftrap = range_check_trap_proj(flip_test, l, r);
 504 
 505   if (iftrap == NULL) {
 506     return 0;
 507   }
 508 
 509   // Make sure it's a real range check by requiring an uncommon trap
 510   // along the OOB path.  Otherwise, it's possible that the user wrote
 511   // something which optimized to look like a range check but behaves
 512   // in some other way.
 513   if (iftrap->is_uncommon_trap_proj(Deoptimization::Reason_range_check) == NULL) {
 514     return 0;
 515   }
 516 
 517   // Look for index+offset form
 518   Node* ind = l;
 519   jint  off = 0;
 520   if (l->is_top()) {
 521     return 0;
 522   } else if (l->Opcode() == Op_AddI) {
 523     if ((off = l->in(1)->find_int_con(0)) != 0) {
 524       ind = l->in(2);
 525     } else if ((off = l->in(2)->find_int_con(0)) != 0) {
 526       ind = l->in(1);
 527     }
 528   } else if ((off = l->find_int_con(-1)) >= 0) {
 529     // constant offset with no variable index
 530     ind = NULL;
 531   } else {
 532     // variable index with no constant offset (or dead negative index)
 533     off = 0;
 534   }
 535 
 536   // Return all the values:
 537   index  = ind;
 538   offset = off;
 539   range  = r;
 540   return flip_test;
 541 }
 542 
 543 //------------------------------adjust_check-----------------------------------
 544 // Adjust (widen) a prior range check
 545 static void adjust_check(Node* proj, Node* range, Node* index,
 546                          int flip, jint off_lo, PhaseIterGVN* igvn) {
 547   PhaseGVN *gvn = igvn;
 548   // Break apart the old check
 549   Node *iff = proj->in(0);
 550   Node *bol = iff->in(1);
 551   if( bol->is_top() ) return;   // In case a partially dead range check appears
 552   // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
 553   DEBUG_ONLY( if( !bol->is_Bool() ) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )
 554   if( !bol->is_Bool() ) return;
 555 
 556   Node *cmp = bol->in(1);
 557   // Compute a new check
 558   Node *new_add = gvn->intcon(off_lo);
 559   if( index ) {
 560     new_add = off_lo ? gvn->transform(new AddINode( index, new_add )) : index;
 561   }
 562   Node *new_cmp = (flip == 1)
 563     ? new CmpUNode( new_add, range )
 564     : new CmpUNode( range, new_add );
 565   new_cmp = gvn->transform(new_cmp);
 566   // See if no need to adjust the existing check
 567   if( new_cmp == cmp ) return;
 568   // Else, adjust existing check
 569   Node *new_bol = gvn->transform( new BoolNode( new_cmp, bol->as_Bool()->_test._test ) );
 570   igvn->rehash_node_delayed( iff );
 571   iff->set_req_X( 1, new_bol, igvn );
 572 }
 573 
 574 //------------------------------up_one_dom-------------------------------------
 575 // Walk up the dominator tree one step.  Return NULL at root or true
 576 // complex merges.  Skips through small diamonds.
 577 Node* IfNode::up_one_dom(Node *curr, bool linear_only) {
 578   Node *dom = curr->in(0);
 579   if( !dom )                    // Found a Region degraded to a copy?
 580     return curr->nonnull_req(); // Skip thru it
 581 
 582   if( curr != dom )             // Normal walk up one step?
 583     return dom;
 584 
 585   // Use linear_only if we are still parsing, since we cannot
 586   // trust the regions to be fully filled in.
 587   if (linear_only)
 588     return NULL;
 589 
 590   if( dom->is_Root() )
 591     return NULL;
 592 
 593   // Else hit a Region.  Check for a loop header
 594   if( dom->is_Loop() )
 595     return dom->in(1);          // Skip up thru loops
 596 
 597   // Check for small diamonds
 598   Node *din1, *din2, *din3, *din4;
 599   if( dom->req() == 3 &&        // 2-path merge point
 600       (din1 = dom ->in(1)) &&   // Left  path exists
 601       (din2 = dom ->in(2)) &&   // Right path exists
 602       (din3 = din1->in(0)) &&   // Left  path up one
 603       (din4 = din2->in(0)) ) {  // Right path up one
 604     if( din3->is_Call() &&      // Handle a slow-path call on either arm
 605         (din3 = din3->in(0)) )
 606       din3 = din3->in(0);
 607     if( din4->is_Call() &&      // Handle a slow-path call on either arm
 608         (din4 = din4->in(0)) )
 609       din4 = din4->in(0);
 610     if( din3 == din4 && din3->is_If() )
 611       return din3;              // Skip around diamonds
 612   }
 613 
 614   // Give up the search at true merges
 615   return NULL;                  // Dead loop?  Or hit root?
 616 }
 617 
 618 
 619 //------------------------------filtered_int_type--------------------------------
 620 // Return a possibly more restrictive type for val based on condition control flow for an if
 621 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node *val, Node* if_proj) {
 622   assert(if_proj &&
 623          (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
 624   if (if_proj->in(0) && if_proj->in(0)->is_If()) {
 625     IfNode* iff = if_proj->in(0)->as_If();
 626     if (iff->in(1) && iff->in(1)->is_Bool()) {
 627       BoolNode* bol = iff->in(1)->as_Bool();
 628       if (bol->in(1) && bol->in(1)->is_Cmp()) {
 629         const CmpNode* cmp  = bol->in(1)->as_Cmp();
 630         if (cmp->in(1) == val) {
 631           const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
 632           if (cmp2_t != NULL) {
 633             jint lo = cmp2_t->_lo;
 634             jint hi = cmp2_t->_hi;
 635             BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
 636             switch (msk) {
 637             case BoolTest::ne:
 638               // Can't refine type
 639               return NULL;
 640             case BoolTest::eq:
 641               return cmp2_t;
 642             case BoolTest::lt:
 643               lo = TypeInt::INT->_lo;
 644               if (hi - 1 < hi) {
 645                 hi = hi - 1;
 646               }
 647               break;
 648             case BoolTest::le:
 649               lo = TypeInt::INT->_lo;
 650               break;
 651             case BoolTest::gt:
 652               if (lo + 1 > lo) {
 653                 lo = lo + 1;
 654               }
 655               hi = TypeInt::INT->_hi;
 656               break;
 657             case BoolTest::ge:
 658               // lo unchanged
 659               hi = TypeInt::INT->_hi;
 660               break;
 661             }
 662             const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
 663             return rtn_t;
 664           }
 665         }
 666       }
 667     }
 668   }
 669   return NULL;
 670 }
 671 
 672 //------------------------------fold_compares----------------------------
 673 // See if a pair of CmpIs can be converted into a CmpU.  In some cases
 674 // the direction of this if is determined by the preceding if so it
 675 // can be eliminate entirely.
 676 //
 677 // Given an if testing (CmpI n v) check for an immediately control
 678 // dependent if that is testing (CmpI n v2) and has one projection
 679 // leading to this if and the other projection leading to a region
 680 // that merges one of this ifs control projections.
 681 //
 682 //                   If
 683 //                  / |
 684 //                 /  |
 685 //                /   |
 686 //              If    |
 687 //              /\    |
 688 //             /  \   |
 689 //            /    \  |
 690 //           /    Region
 691 //
 692 // Or given an if testing (CmpI n v) check for a dominating if that is
 693 // testing (CmpI n v2), both having one projection leading to an
 694 // uncommon trap. Allow Another independent guard in between to cover
 695 // an explicit range check:
 696 // if (index < 0 || index >= array.length) {
 697 // which may need a null check to guard the LoadRange
 698 //
 699 //                   If
 700 //                  / \
 701 //                 /   \
 702 //                /     \
 703 //              If      unc
 704 //              /\
 705 //             /  \
 706 //            /    \
 707 //           /      unc
 708 //
 709 
 710 // Is the comparison for this If suitable for folding?
 711 bool IfNode::cmpi_folds(PhaseIterGVN* igvn) {
 712   return in(1) != NULL &&
 713     in(1)->is_Bool() &&
 714     in(1)->in(1) != NULL &&
 715     in(1)->in(1)->Opcode() == Op_CmpI &&
 716     in(1)->in(1)->in(2) != NULL &&
 717     in(1)->in(1)->in(2) != igvn->C->top() &&
 718     (in(1)->as_Bool()->_test.is_less() ||
 719      in(1)->as_Bool()->_test.is_greater());
 720 }
 721 
 722 // Is a dominating control suitable for folding with this if?
 723 bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) {
 724   return ctrl != NULL &&
 725     ctrl->is_Proj() &&
 726     ctrl->in(0) != NULL &&
 727     ctrl->in(0)->is_If() &&
 728     ctrl->in(0)->outcnt() == 2 &&
 729     ctrl->in(0)->as_If()->cmpi_folds(igvn) &&
 730     // Must compare same value
 731     ctrl->in(0)->in(1)->in(1)->in(1) != NULL &&
 732     ctrl->in(0)->in(1)->in(1)->in(1) == in(1)->in(1)->in(1);
 733 }
 734 
 735 // Do this If and the dominating If share a region?
 736 bool IfNode::has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail) {
 737   ProjNode* otherproj = proj->other_if_proj();
 738   Node* otherproj_ctrl_use = otherproj->unique_ctrl_out();
 739   RegionNode* region = (otherproj_ctrl_use != NULL && otherproj_ctrl_use->is_Region()) ? otherproj_ctrl_use->as_Region() : NULL;
 740   success = NULL;
 741   fail = NULL;
 742 
 743   if (otherproj->outcnt() == 1 && region != NULL && !region->has_phi()) {
 744     for (int i = 0; i < 2; i++) {
 745       ProjNode* proj = proj_out(i);
 746       if (success == NULL && proj->outcnt() == 1 && proj->unique_out() == region) {
 747         success = proj;
 748       } else if (fail == NULL) {
 749         fail = proj;
 750       } else {
 751         success = fail = NULL;
 752       }
 753     }
 754   }
 755   return success != NULL && fail != NULL;
 756 }
 757 
 758 // Return projection that leads to an uncommon trap if any
 759 ProjNode* IfNode::uncommon_trap_proj(CallStaticJavaNode*& call) const {
 760   for (int i = 0; i < 2; i++) {
 761     call = proj_out(i)->is_uncommon_trap_proj(Deoptimization::Reason_none);
 762     if (call != NULL) {
 763       return proj_out(i);
 764     }
 765   }
 766   return NULL;
 767 }
 768 
 769 // Do this If and the dominating If both branch out to an uncommon trap
 770 bool IfNode::has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn) {
 771   ProjNode* otherproj = proj->other_if_proj();
 772   // Dominating uncommon trap must have 'Reason_unstable_if' to ensure re-execution of folded Ifs
 773   CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_unstable_if);
 774 
 775   if (otherproj->outcnt() == 1 && dom_unc != NULL) {
 776     CallStaticJavaNode* unc = NULL;
 777     ProjNode* unc_proj = uncommon_trap_proj(unc);
 778     if (unc_proj != NULL && unc_proj->outcnt() == 1) {
 779       if (dom_unc == unc) {
 780         // Allow the uncommon trap to be shared through a region
 781         RegionNode* r = unc->in(0)->as_Region();
 782         if (r->outcnt() != 2 || r->req() != 3 || r->find_edge(otherproj) == -1 || r->find_edge(unc_proj) == -1) {
 783           return false;
 784         }
 785         assert(r->has_phi() == NULL, "simple region shouldn't have a phi");
 786       } else if (dom_unc->in(0) != otherproj || unc->in(0) != unc_proj) {
 787         return false;
 788       }
 789 
 790       // Check if the bci of the dominating uncommon trap dominates the bci
 791       // of the dominated uncommon trap. Otherwise we may not re-execute
 792       // the dominated check after deoptimization from the merged uncommon trap.
 793       ciMethod* method = unc->jvms()->method();
 794       ciMethod* dom_method = dom_unc->jvms()->method();
 795       if (method != dom_method) {
 796         return false;
 797       }
 798       ciTypeFlow* flow = dom_method->get_flow_analysis();
 799       int bci = unc->jvms()->bci();
 800       int dom_bci = dom_unc->jvms()->bci();
 801       if (!flow->is_dominated_by(bci, dom_bci)) {
 802         return false;
 803       }
 804 
 805       // See merge_uncommon_traps: the reason of the uncommon trap
 806       // will be changed and the state of the dominating If will be
 807       // used. Checked that we didn't apply this transformation in a
 808       // previous compilation and it didn't cause too many traps
 809       if (!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_unstable_fused_if) &&
 810           !igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_range_check)) {
 811         success = unc_proj;
 812         fail = unc_proj->other_if_proj();
 813         return true;
 814       }
 815     }
 816   }
 817   return false;
 818 }
 819 
 820 // Check that the 2 CmpI can be folded into as single CmpU and proceed with the folding
 821 bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
 822   Node* this_cmp = in(1)->in(1);
 823   BoolNode* this_bool = in(1)->as_Bool();
 824   IfNode* dom_iff = proj->in(0)->as_If();
 825   BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
 826   Node* lo = dom_iff->in(1)->in(1)->in(2);
 827   Node* hi = this_cmp->in(2);
 828   Node* n = this_cmp->in(1);
 829   ProjNode* otherproj = proj->other_if_proj();
 830 
 831   const TypeInt* lo_type = IfNode::filtered_int_type(igvn, n, otherproj);
 832   const TypeInt* hi_type = IfNode::filtered_int_type(igvn, n, success);
 833 
 834   BoolTest::mask lo_test = dom_bool->_test._test;
 835   BoolTest::mask hi_test = this_bool->_test._test;
 836   BoolTest::mask cond = hi_test;
 837 
 838   // convert:
 839   //
 840   //          dom_bool = x {<,<=,>,>=} a
 841   //                           / \
 842   //     proj = {True,False}  /   \ otherproj = {False,True}
 843   //                         /
 844   //        this_bool = x {<,<=} b
 845   //                       / \
 846   //  fail = {True,False} /   \ success = {False,True}
 847   //                     /
 848   //
 849   // (Second test guaranteed canonicalized, first one may not have
 850   // been canonicalized yet)
 851   //
 852   // into:
 853   //
 854   // cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim
 855   //                       / \
 856   //                 fail /   \ success
 857   //                     /
 858   //
 859 
 860   // Figure out which of the two tests sets the upper bound and which
 861   // sets the lower bound if any.
 862   Node* adjusted_lim = NULL;
 863   if (hi_type->_lo > lo_type->_hi && hi_type->_hi == max_jint && lo_type->_lo == min_jint) {
 864     assert((dom_bool->_test.is_less() && !proj->_con) ||
 865            (dom_bool->_test.is_greater() && proj->_con), "incorrect test");
 866     // this test was canonicalized
 867     assert(this_bool->_test.is_less() && fail->_con, "incorrect test");
 868 
 869     // this_bool = <
 870     //   dom_bool = >= (proj = True) or dom_bool = < (proj = False)
 871     //     x in [a, b[ on the fail (= True) projection, b > a-1 (because of hi_type->_lo > lo_type->_hi test above):
 872     //     lo = a, hi = b, adjusted_lim = b-a, cond = <u
 873     //   dom_bool = > (proj = True) or dom_bool = <= (proj = False)
 874     //     x in ]a, b[ on the fail (= True) projection, b > a:
 875     //     lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <u
 876     // this_bool = <=
 877     //   dom_bool = >= (proj = True) or dom_bool = < (proj = False)
 878     //     x in [a, b] on the fail (= True) projection, b+1 > a-1:
 879     //     lo = a, hi = b, adjusted_lim = b-a+1, cond = <u
 880     //     lo = a, hi = b, adjusted_lim = b-a, cond = <=u doesn't work because b = a - 1 is possible, then b-a = -1
 881     //   dom_bool = > (proj = True) or dom_bool = <= (proj = False)
 882     //     x in ]a, b] on the fail (= True) projection b+1 > a:
 883     //     lo = a+1, hi = b, adjusted_lim = b-a, cond = <u
 884     //     lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <=u doesn't work because a = b is possible, then b-a-1 = -1
 885 
 886     if (hi_test == BoolTest::lt) {
 887       if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
 888         lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
 889       }
 890     } else {
 891       assert(hi_test == BoolTest::le, "bad test");
 892       if (lo_test == BoolTest::ge || lo_test == BoolTest::lt) {
 893         adjusted_lim = igvn->transform(new SubINode(hi, lo));
 894         adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
 895         cond = BoolTest::lt;
 896       } else {
 897         assert(lo_test == BoolTest::gt || lo_test == BoolTest::le, "bad test");
 898         adjusted_lim = igvn->transform(new SubINode(hi, lo));
 899         lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
 900         cond = BoolTest::lt;
 901       }
 902     }
 903   } else if (lo_type->_lo > hi_type->_hi && lo_type->_hi == max_jint && hi_type->_lo == min_jint) {
 904 
 905     // this_bool = <
 906     //   dom_bool = < (proj = True) or dom_bool = >= (proj = False)
 907     //     x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above):
 908     //     lo = b, hi = a, adjusted_lim = a-b, cond = >=u
 909     //   dom_bool = <= (proj = True) or dom_bool = > (proj = False)
 910     //     x in [b, a] on the fail (= False) projection, a+1 > b-1:
 911     //     lo = b, hi = a, adjusted_lim = a-b+1, cond = >=u
 912     //     lo = b, hi = a, adjusted_lim = a-b, cond = >u doesn't work because a = b - 1 is possible, then b-a = -1
 913     // this_bool = <=
 914     //   dom_bool = < (proj = True) or dom_bool = >= (proj = False)
 915     //     x in ]b, a[ on the fail (= False) projection, a > b:
 916     //     lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u
 917     //   dom_bool = <= (proj = True) or dom_bool = > (proj = False)
 918     //     x in ]b, a] on the fail (= False) projection, a+1 > b:
 919     //     lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u
 920     //     lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >u doesn't work because a = b is possible, then b-a-1 = -1
 921 
 922     swap(lo, hi);
 923     swap(lo_type, hi_type);
 924     swap(lo_test, hi_test);
 925 
 926     assert((dom_bool->_test.is_less() && proj->_con) ||
 927            (dom_bool->_test.is_greater() && !proj->_con), "incorrect test");
 928     // this test was canonicalized
 929     assert(this_bool->_test.is_less() && !fail->_con, "incorrect test");
 930 
 931     cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge;
 932 
 933     if (lo_test == BoolTest::lt) {
 934       if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
 935         cond = BoolTest::ge;
 936       } else {
 937         assert(hi_test == BoolTest::le || hi_test == BoolTest::gt, "bad test");
 938         adjusted_lim = igvn->transform(new SubINode(hi, lo));
 939         adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
 940         cond = BoolTest::ge;
 941       }
 942     } else if (lo_test == BoolTest::le) {
 943       if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
 944         lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
 945         cond = BoolTest::ge;
 946       } else {
 947         assert(hi_test == BoolTest::le || hi_test == BoolTest::gt, "bad test");
 948         adjusted_lim = igvn->transform(new SubINode(hi, lo));
 949         lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
 950         cond = BoolTest::ge;
 951       }
 952     }
 953   } else {
 954     const TypeInt* failtype  = filtered_int_type(igvn, n, proj);
 955     if (failtype != NULL) {
 956       const TypeInt* type2 = filtered_int_type(igvn, n, fail);
 957       if (type2 != NULL) {
 958         failtype = failtype->join(type2)->is_int();
 959         if (failtype->_lo > failtype->_hi) {
 960           // previous if determines the result of this if so
 961           // replace Bool with constant
 962           igvn->hash_delete(this);
 963           set_req(1, igvn->intcon(success->_con));
 964           return true;
 965         }
 966       }
 967     }
 968     lo = NULL;
 969     hi = NULL;
 970   }
 971 
 972   if (lo && hi) {
 973     // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo))
 974     Node* adjusted_val = igvn->transform(new SubINode(n,  lo));
 975     if (adjusted_lim == NULL) {
 976       adjusted_lim = igvn->transform(new SubINode(hi, lo));
 977     }
 978     Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim));
 979     Node* newbool = igvn->transform(new BoolNode(newcmp, cond));
 980 
 981     igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con));
 982     set_req(1, newbool);
 983 
 984     return true;
 985   }
 986   return false;
 987 }
 988 
 989 // Merge the branches that trap for this If and the dominating If into
 990 // a single region that branches to the uncommon trap for the
 991 // dominating If
 992 void IfNode::merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
 993   ProjNode* otherproj = proj->other_if_proj();
 994 
 995   CallStaticJavaNode* unc = success->is_uncommon_trap_proj(Deoptimization::Reason_none);
 996   CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj(Deoptimization::Reason_none);
 997 
 998   if (unc != dom_unc) {
 999     Node* r = new RegionNode(3);
1000 
1001     r->set_req(1, otherproj);
1002     r->set_req(2, success);
1003     r = igvn->transform(r);
1004     assert(r->is_Region(), "can't go away");
1005 
1006     // Make both If trap at the state of the first If: once the CmpI
1007     // nodes are merged, if we trap we don't know which of the CmpI
1008     // nodes would have caused the trap so we have to restart
1009     // execution at the first one
1010     igvn->replace_input_of(dom_unc, 0, r);
1011     igvn->replace_input_of(unc, 0, igvn->C->top());
1012   }
1013   int trap_request = dom_unc->uncommon_trap_request();
1014   Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1015   Deoptimization::DeoptAction action = Deoptimization::trap_request_action(trap_request);
1016 
1017   int flip_test = 0;
1018   Node* l = NULL;
1019   Node* r = NULL;
1020 
1021   if (success->in(0)->as_If()->range_check_trap_proj(flip_test, l, r) != NULL) {
1022     // If this looks like a range check, change the trap to
1023     // Reason_range_check so the compiler recognizes it as a range
1024     // check and applies the corresponding optimizations
1025     trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_range_check, action);
1026 
1027     improve_address_types(l, r, fail, igvn);
1028   } else if (unc != dom_unc) {
1029     // If we trap we won't know what CmpI would have caused the trap
1030     // so use a special trap reason to mark this pair of CmpI nodes as
1031     // bad candidate for folding. On recompilation we won't fold them
1032     // and we may trap again but this time we'll know what branch
1033     // traps
1034     trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_unstable_fused_if, action);
1035   }
1036   igvn->replace_input_of(dom_unc, TypeFunc::Parms, igvn->intcon(trap_request));
1037 }
1038 
1039 // If we are turning 2 CmpI nodes into a CmpU that follows the pattern
1040 // of a rangecheck on index i, on 64 bit the compares may be followed
1041 // by memory accesses using i as index. In that case, the CmpU tells
1042 // us something about the values taken by i that can help the compiler
1043 // (see Compile::conv_I2X_index())
1044 void IfNode::improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn) {
1045 #ifdef _LP64
1046   ResourceMark rm;
1047   Node_Stack stack(2);
1048 
1049   assert(r->Opcode() == Op_LoadRange, "unexpected range check");
1050   const TypeInt* array_size = igvn->type(r)->is_int();
1051 
1052   stack.push(l, 0);
1053 
1054   while(stack.size() > 0) {
1055     Node* n = stack.node();
1056     uint start = stack.index();
1057 
1058     uint i = start;
1059     for (; i < n->outcnt(); i++) {
1060       Node* use = n->raw_out(i);
1061       if (stack.size() == 1) {
1062         if (use->Opcode() == Op_ConvI2L) {
1063           const TypeLong* bounds = use->as_Type()->type()->is_long();
1064           if (bounds->_lo <= array_size->_lo && bounds->_hi >= array_size->_hi &&
1065               (bounds->_lo != array_size->_lo || bounds->_hi != array_size->_hi)) {
1066             stack.set_index(i+1);
1067             stack.push(use, 0);
1068             break;
1069           }
1070         }
1071       } else if (use->is_Mem()) {
1072         Node* ctrl = use->in(0);
1073         for (int i = 0; i < 10 && ctrl != NULL && ctrl != fail; i++) {
1074           ctrl = up_one_dom(ctrl);
1075         }
1076         if (ctrl == fail) {
1077           Node* init_n = stack.node_at(1);
1078           assert(init_n->Opcode() == Op_ConvI2L, "unexpected first node");
1079           Node* new_n = igvn->C->conv_I2X_index(igvn, l, array_size);
1080 
1081           // The type of the ConvI2L may be widen and so the new
1082           // ConvI2L may not be better than an existing ConvI2L
1083           if (new_n != init_n) {
1084             for (uint j = 2; j < stack.size(); j++) {
1085               Node* n = stack.node_at(j);
1086               Node* clone = n->clone();
1087               int rep = clone->replace_edge(init_n, new_n);
1088               assert(rep > 0, "can't find expected node?");
1089               clone = igvn->transform(clone);
1090               init_n = n;
1091               new_n = clone;
1092             }
1093             igvn->hash_delete(use);
1094             int rep = use->replace_edge(init_n, new_n);
1095             assert(rep > 0, "can't find expected node?");
1096             igvn->transform(use);
1097             if (init_n->outcnt() == 0) {
1098               igvn->_worklist.push(init_n);
1099             }
1100           }
1101         }
1102       } else if (use->in(0) == NULL && (igvn->type(use)->isa_long() ||
1103                                         igvn->type(use)->isa_ptr())) {
1104         stack.set_index(i+1);
1105         stack.push(use, 0);
1106         break;
1107       }
1108     }
1109     if (i == n->outcnt()) {
1110       stack.pop();
1111     }
1112   }
1113 #endif
1114 }
1115 
1116 bool IfNode::is_cmp_with_loadrange(ProjNode* proj) {
1117   if (in(1) != NULL &&
1118       in(1)->in(1) != NULL &&
1119       in(1)->in(1)->in(2) != NULL) {
1120     Node* other = in(1)->in(1)->in(2);
1121     if (other->Opcode() == Op_LoadRange &&
1122         ((other->in(0) != NULL && other->in(0) == proj) ||
1123          (other->in(0) == NULL &&
1124           other->in(2) != NULL &&
1125           other->in(2)->is_AddP() &&
1126           other->in(2)->in(1) != NULL &&
1127           other->in(2)->in(1)->Opcode() == Op_CastPP &&
1128           other->in(2)->in(1)->in(0) == proj))) {
1129       return true;
1130     }
1131   }
1132   return false;
1133 }
1134 
1135 bool IfNode::is_null_check(ProjNode* proj, PhaseIterGVN* igvn) {
1136   Node* other = in(1)->in(1)->in(2);
1137   if (other->in(MemNode::Address) != NULL &&
1138       proj->in(0)->in(1) != NULL &&
1139       proj->in(0)->in(1)->is_Bool() &&
1140       proj->in(0)->in(1)->in(1) != NULL &&
1141       proj->in(0)->in(1)->in(1)->Opcode() == Op_CmpP &&
1142       proj->in(0)->in(1)->in(1)->in(2) != NULL &&
1143       proj->in(0)->in(1)->in(1)->in(1) == other->in(MemNode::Address)->in(AddPNode::Address)->uncast() &&
1144       igvn->type(proj->in(0)->in(1)->in(1)->in(2)) == TypePtr::NULL_PTR) {
1145     return true;
1146   }
1147   return false;
1148 }
1149 
1150 // Check that the If that is in between the 2 integer comparisons has
1151 // no side effect
1152 bool IfNode::is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn) {
1153   if (proj != NULL &&
1154       proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) &&
1155       proj->outcnt() <= 2) {
1156     if (proj->outcnt() == 1 ||
1157         // Allow simple null check from LoadRange
1158         (is_cmp_with_loadrange(proj) && is_null_check(proj, igvn))) {
1159       CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1160       CallStaticJavaNode* dom_unc = proj->in(0)->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1161 
1162       // reroute_side_effect_free_unc changes the state of this
1163       // uncommon trap to restart execution at the previous
1164       // CmpI. Check that this change in a previous compilation didn't
1165       // cause too many traps.
1166       int trap_request = unc->uncommon_trap_request();
1167       Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1168 
1169       if (igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), reason)) {
1170         return false;
1171       }
1172 
1173       return true;
1174     }
1175   }
1176   return false;
1177 }
1178 
1179 // Make the If between the 2 integer comparisons trap at the state of
1180 // the first If: the last CmpI is the one replaced by a CmpU and the
1181 // first CmpI is eliminated, so the test between the 2 CmpI nodes
1182 // won't be guarded by the first CmpI anymore. It can trap in cases
1183 // where the first CmpI would have prevented it from executing: on a
1184 // trap, we need to restart execution at the state of the first CmpI
1185 void IfNode::reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn) {
1186   CallStaticJavaNode* dom_unc = dom_proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1187   ProjNode* otherproj = proj->other_if_proj();
1188   CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
1189   Node* call_proj = dom_unc->unique_ctrl_out();
1190   Node* halt = call_proj->unique_ctrl_out();
1191 
1192   Node* new_unc = dom_unc->clone();
1193   call_proj = call_proj->clone();
1194   halt = halt->clone();
1195   Node* c = otherproj->clone();
1196 
1197   c = igvn->transform(c);
1198   new_unc->set_req(TypeFunc::Parms, unc->in(TypeFunc::Parms));
1199   new_unc->set_req(0, c);
1200   new_unc = igvn->transform(new_unc);
1201   call_proj->set_req(0, new_unc);
1202   call_proj = igvn->transform(call_proj);
1203   halt->set_req(0, call_proj);
1204   halt = igvn->transform(halt);
1205 
1206   igvn->replace_node(otherproj, igvn->C->top());
1207   igvn->C->root()->add_req(halt);
1208 }
1209 
1210 Node* IfNode::fold_compares(PhaseIterGVN* igvn) {
1211   if (Opcode() != Op_If) return NULL;
1212 
1213   if (cmpi_folds(igvn)) {
1214     Node* ctrl = in(0);
1215     if (is_ctrl_folds(ctrl, igvn) &&
1216         ctrl->outcnt() == 1) {
1217       // A integer comparison immediately dominated by another integer
1218       // comparison
1219       ProjNode* success = NULL;
1220       ProjNode* fail = NULL;
1221       ProjNode* dom_cmp = ctrl->as_Proj();
1222       if (has_shared_region(dom_cmp, success, fail) &&
1223           // Next call modifies graph so must be last
1224           fold_compares_helper(dom_cmp, success, fail, igvn)) {
1225         return this;
1226       }
1227       if (has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1228           // Next call modifies graph so must be last
1229           fold_compares_helper(dom_cmp, success, fail, igvn)) {
1230         merge_uncommon_traps(dom_cmp, success, fail, igvn);
1231         return this;
1232       }
1233       return NULL;
1234     } else if (ctrl->in(0) != NULL &&
1235                ctrl->in(0)->in(0) != NULL) {
1236       ProjNode* success = NULL;
1237       ProjNode* fail = NULL;
1238       Node* dom = ctrl->in(0)->in(0);
1239       ProjNode* dom_cmp = dom->isa_Proj();
1240       ProjNode* other_cmp = ctrl->isa_Proj();
1241 
1242       // Check if it's an integer comparison dominated by another
1243       // integer comparison with another test in between
1244       if (is_ctrl_folds(dom, igvn) &&
1245           has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1246           is_side_effect_free_test(other_cmp, igvn) &&
1247           // Next call modifies graph so must be last
1248           fold_compares_helper(dom_cmp, success, fail, igvn)) {
1249         reroute_side_effect_free_unc(other_cmp, dom_cmp, igvn);
1250         merge_uncommon_traps(dom_cmp, success, fail, igvn);
1251         return this;
1252       }
1253     }
1254   }
1255   return NULL;
1256 }
1257 
1258 //------------------------------remove_useless_bool----------------------------
1259 // Check for people making a useless boolean: things like
1260 // if( (x < y ? true : false) ) { ... }
1261 // Replace with if( x < y ) { ... }
1262 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {
1263   Node *i1 = iff->in(1);
1264   if( !i1->is_Bool() ) return NULL;
1265   BoolNode *bol = i1->as_Bool();
1266 
1267   Node *cmp = bol->in(1);
1268   if( cmp->Opcode() != Op_CmpI ) return NULL;
1269 
1270   // Must be comparing against a bool
1271   const Type *cmp2_t = phase->type( cmp->in(2) );
1272   if( cmp2_t != TypeInt::ZERO &&
1273       cmp2_t != TypeInt::ONE )
1274     return NULL;
1275 
1276   // Find a prior merge point merging the boolean
1277   i1 = cmp->in(1);
1278   if( !i1->is_Phi() ) return NULL;
1279   PhiNode *phi = i1->as_Phi();
1280   if( phase->type( phi ) != TypeInt::BOOL )
1281     return NULL;
1282 
1283   // Check for diamond pattern
1284   int true_path = phi->is_diamond_phi();
1285   if( true_path == 0 ) return NULL;
1286 
1287   // Make sure that iff and the control of the phi are different. This
1288   // should really only happen for dead control flow since it requires
1289   // an illegal cycle.
1290   if (phi->in(0)->in(1)->in(0) == iff) return NULL;
1291 
1292   // phi->region->if_proj->ifnode->bool->cmp
1293   BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
1294 
1295   // Now get the 'sense' of the test correct so we can plug in
1296   // either iff2->in(1) or its complement.
1297   int flip = 0;
1298   if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
1299   else if( bol->_test._test != BoolTest::eq ) return NULL;
1300   if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
1301 
1302   const Type *phi1_t = phase->type( phi->in(1) );
1303   const Type *phi2_t = phase->type( phi->in(2) );
1304   // Check for Phi(0,1) and flip
1305   if( phi1_t == TypeInt::ZERO ) {
1306     if( phi2_t != TypeInt::ONE ) return NULL;
1307     flip = 1-flip;
1308   } else {
1309     // Check for Phi(1,0)
1310     if( phi1_t != TypeInt::ONE  ) return NULL;
1311     if( phi2_t != TypeInt::ZERO ) return NULL;
1312   }
1313   if( true_path == 2 ) {
1314     flip = 1-flip;
1315   }
1316 
1317   Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
1318   assert(new_bol != iff->in(1), "must make progress");
1319   iff->set_req(1, new_bol);
1320   // Intervening diamond probably goes dead
1321   phase->C->set_major_progress();
1322   return iff;
1323 }
1324 
1325 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
1326 
1327 struct RangeCheck {
1328   Node* ctl;
1329   jint off;
1330 };
1331 
1332 //------------------------------Ideal------------------------------------------
1333 // Return a node which is more "ideal" than the current node.  Strip out
1334 // control copies
1335 Node *IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1336   if (remove_dead_region(phase, can_reshape))  return this;
1337   // No Def-Use info?
1338   if (!can_reshape)  return NULL;
1339   PhaseIterGVN *igvn = phase->is_IterGVN();
1340 
1341   // Don't bother trying to transform a dead if
1342   if (in(0)->is_top())  return NULL;
1343   // Don't bother trying to transform an if with a dead test
1344   if (in(1)->is_top())  return NULL;
1345   // Another variation of a dead test
1346   if (in(1)->is_Con())  return NULL;
1347   // Another variation of a dead if
1348   if (outcnt() < 2)  return NULL;
1349 
1350   // Canonicalize the test.
1351   Node* idt_if = idealize_test(phase, this);
1352   if (idt_if != NULL)  return idt_if;
1353 
1354   // Try to split the IF
1355   Node *s = split_if(this, igvn);
1356   if (s != NULL)  return s;
1357 
1358   // Check for people making a useless boolean: things like
1359   // if( (x < y ? true : false) ) { ... }
1360   // Replace with if( x < y ) { ... }
1361   Node *bol2 = remove_useless_bool(this, phase);
1362   if( bol2 ) return bol2;
1363 
1364   // Setup to scan up the CFG looking for a dominating test
1365   Node *dom = in(0);
1366   Node *prev_dom = this;
1367 
1368   // Check for range-check vs other kinds of tests
1369   Node *index1, *range1;
1370   jint offset1;
1371   int flip1 = is_range_check(range1, index1, offset1);
1372   if( flip1 ) {
1373     // Try to remove extra range checks.  All 'up_one_dom' gives up at merges
1374     // so all checks we inspect post-dominate the top-most check we find.
1375     // If we are going to fail the current check and we reach the top check
1376     // then we are guaranteed to fail, so just start interpreting there.
1377     // We 'expand' the top 3 range checks to include all post-dominating
1378     // checks.
1379 
1380     // The top 3 range checks seen
1381     const int NRC =3;
1382     RangeCheck prev_checks[NRC];
1383     int nb_checks = 0;
1384 
1385     // Low and high offsets seen so far
1386     jint off_lo = offset1;
1387     jint off_hi = offset1;
1388 
1389     bool found_immediate_dominator = false;
1390 
1391     // Scan for the top checks and collect range of offsets
1392     for (int dist = 0; dist < 999; dist++) { // Range-Check scan limit
1393       if (dom->Opcode() == Op_If &&  // Not same opcode?
1394           prev_dom->in(0) == dom) { // One path of test does dominate?
1395         if (dom == this) return NULL; // dead loop
1396         // See if this is a range check
1397         Node *index2, *range2;
1398         jint offset2;
1399         int flip2 = dom->as_If()->is_range_check(range2, index2, offset2);
1400         // See if this is a _matching_ range check, checking against
1401         // the same array bounds.
1402         if (flip2 == flip1 && range2 == range1 && index2 == index1 &&
1403             dom->outcnt() == 2) {
1404           if (nb_checks == 0 && dom->in(1) == in(1)) {
1405             // Found an immediately dominating test at the same offset.
1406             // This kind of back-to-back test can be eliminated locally,
1407             // and there is no need to search further for dominating tests.
1408             assert(offset2 == offset1, "Same test but different offsets");
1409             found_immediate_dominator = true;
1410             break;
1411           }
1412           // Gather expanded bounds
1413           off_lo = MIN2(off_lo,offset2);
1414           off_hi = MAX2(off_hi,offset2);
1415           // Record top NRC range checks
1416           prev_checks[nb_checks%NRC].ctl = prev_dom;
1417           prev_checks[nb_checks%NRC].off = offset2;
1418           nb_checks++;
1419         }
1420       }
1421       prev_dom = dom;
1422       dom = up_one_dom(dom);
1423       if (!dom) break;
1424     }
1425 
1426     if (!found_immediate_dominator) {
1427       // Attempt to widen the dominating range check to cover some later
1428       // ones.  Since range checks "fail" by uncommon-trapping to the
1429       // interpreter, widening a check can make us speculatively enter
1430       // the interpreter.  If we see range-check deopt's, do not widen!
1431       if (!phase->C->allow_range_check_smearing())  return NULL;
1432 
1433       // Didn't find prior covering check, so cannot remove anything.
1434       if (nb_checks == 0) {
1435         return NULL;
1436       }
1437       // Constant indices only need to check the upper bound.
1438       // Non-constant indices must check both low and high.
1439       int chk0 = (nb_checks - 1) % NRC;
1440       if (index1) {
1441         if (nb_checks == 1) {
1442           return NULL;
1443         } else {
1444           // If the top range check's constant is the min or max of
1445           // all constants we widen the next one to cover the whole
1446           // range of constants.
1447           RangeCheck rc0 = prev_checks[chk0];
1448           int chk1 = (nb_checks - 2) % NRC;
1449           RangeCheck rc1 = prev_checks[chk1];
1450           if (rc0.off == off_lo) {
1451             adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
1452             prev_dom = rc1.ctl;
1453           } else if (rc0.off == off_hi) {
1454             adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
1455             prev_dom = rc1.ctl;
1456           } else {
1457             // If the top test's constant is not the min or max of all
1458             // constants, we need 3 range checks. We must leave the
1459             // top test unchanged because widening it would allow the
1460             // accesses it protects to successfully read/write out of
1461             // bounds.
1462             if (nb_checks == 2) {
1463               return NULL;
1464             }
1465             int chk2 = (nb_checks - 3) % NRC;
1466             RangeCheck rc2 = prev_checks[chk2];
1467             // The top range check a+i covers interval: -a <= i < length-a
1468             // The second range check b+i covers interval: -b <= i < length-b
1469             if (rc1.off <= rc0.off) {
1470               // if b <= a, we change the second range check to:
1471               // -min_of_all_constants <= i < length-min_of_all_constants
1472               // Together top and second range checks now cover:
1473               // -min_of_all_constants <= i < length-a
1474               // which is more restrictive than -b <= i < length-b:
1475               // -b <= -min_of_all_constants <= i < length-a <= length-b
1476               // The third check is then changed to:
1477               // -max_of_all_constants <= i < length-max_of_all_constants
1478               // so 2nd and 3rd checks restrict allowed values of i to:
1479               // -min_of_all_constants <= i < length-max_of_all_constants
1480               adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
1481               adjust_check(rc2.ctl, range1, index1, flip1, off_hi, igvn);
1482             } else {
1483               // if b > a, we change the second range check to:
1484               // -max_of_all_constants <= i < length-max_of_all_constants
1485               // Together top and second range checks now cover:
1486               // -a <= i < length-max_of_all_constants
1487               // which is more restrictive than -b <= i < length-b:
1488               // -b < -a <= i < length-max_of_all_constants <= length-b
1489               // The third check is then changed to:
1490               // -max_of_all_constants <= i < length-max_of_all_constants
1491               // so 2nd and 3rd checks restrict allowed values of i to:
1492               // -min_of_all_constants <= i < length-max_of_all_constants
1493               adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
1494               adjust_check(rc2.ctl, range1, index1, flip1, off_lo, igvn);
1495             }
1496             prev_dom = rc2.ctl;
1497           }
1498         }
1499       } else {
1500         RangeCheck rc0 = prev_checks[chk0];
1501         // 'Widen' the offset of the 1st and only covering check
1502         adjust_check(rc0.ctl, range1, index1, flip1, off_hi, igvn);
1503         // Test is now covered by prior checks, dominate it out
1504         prev_dom = rc0.ctl;
1505       }
1506     }
1507 
1508   } else {                      // Scan for an equivalent test
1509 
1510     Node *cmp;
1511     int dist = 0;               // Cutoff limit for search
1512     int op = Opcode();
1513     if( op == Op_If &&
1514         (cmp=in(1)->in(1))->Opcode() == Op_CmpP ) {
1515       if( cmp->in(2) != NULL && // make sure cmp is not already dead
1516           cmp->in(2)->bottom_type() == TypePtr::NULL_PTR ) {
1517         dist = 64;              // Limit for null-pointer scans
1518       } else {
1519         dist = 4;               // Do not bother for random pointer tests
1520       }
1521     } else {
1522       dist = 4;                 // Limit for random junky scans
1523     }
1524 
1525     // Normal equivalent-test check.
1526     if( !dom ) return NULL;     // Dead loop?
1527 
1528     Node* result = fold_compares(igvn);
1529     if (result != NULL) {
1530       return result;
1531     }
1532 
1533     // Search up the dominator tree for an If with an identical test
1534     while( dom->Opcode() != op    ||  // Not same opcode?
1535            dom->in(1)    != in(1) ||  // Not same input 1?
1536            (req() == 3 && dom->in(2) != in(2)) || // Not same input 2?
1537            prev_dom->in(0) != dom ) { // One path of test does not dominate?
1538       if( dist < 0 ) return NULL;
1539 
1540       dist--;
1541       prev_dom = dom;
1542       dom = up_one_dom( dom );
1543       if( !dom ) return NULL;
1544     }
1545 
1546     // Check that we did not follow a loop back to ourselves
1547     if( this == dom )
1548       return NULL;
1549 
1550     if( dist > 2 )              // Add to count of NULL checks elided
1551       explicit_null_checks_elided++;
1552 
1553   } // End of Else scan for an equivalent test
1554 
1555   // Hit!  Remove this IF
1556 #ifndef PRODUCT
1557   if( TraceIterativeGVN ) {
1558     tty->print("   Removing IfNode: "); this->dump();
1559   }
1560   if( VerifyOpto && !phase->allow_progress() ) {
1561     // Found an equivalent dominating test,
1562     // we can not guarantee reaching a fix-point for these during iterativeGVN
1563     // since intervening nodes may not change.
1564     return NULL;
1565   }
1566 #endif
1567 
1568   // Replace dominated IfNode
1569   dominated_by( prev_dom, igvn );
1570 
1571   // Must return either the original node (now dead) or a new node
1572   // (Do not return a top here, since that would break the uniqueness of top.)
1573   return new ConINode(TypeInt::ZERO);
1574 }
1575 
1576 //------------------------------dominated_by-----------------------------------
1577 void IfNode::dominated_by( Node *prev_dom, PhaseIterGVN *igvn ) {
1578   igvn->hash_delete(this);      // Remove self to prevent spurious V-N
1579   Node *idom = in(0);
1580   // Need opcode to decide which way 'this' test goes
1581   int prev_op = prev_dom->Opcode();
1582   Node *top = igvn->C->top(); // Shortcut to top
1583 
1584   // Loop predicates may have depending checks which should not
1585   // be skipped. For example, range check predicate has two checks
1586   // for lower and upper bounds.
1587   ProjNode* unc_proj = proj_out(1 - prev_dom->as_Proj()->_con)->as_Proj();
1588   if (unc_proj->is_uncommon_trap_proj(Deoptimization::Reason_predicate) != NULL)
1589    prev_dom = idom;
1590 
1591   // Now walk the current IfNode's projections.
1592   // Loop ends when 'this' has no more uses.
1593   for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1594     Node *ifp = last_out(i);     // Get IfTrue/IfFalse
1595     igvn->add_users_to_worklist(ifp);
1596     // Check which projection it is and set target.
1597     // Data-target is either the dominating projection of the same type
1598     // or TOP if the dominating projection is of opposite type.
1599     // Data-target will be used as the new control edge for the non-CFG
1600     // nodes like Casts and Loads.
1601     Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top;
1602     // Control-target is just the If's immediate dominator or TOP.
1603     Node *ctrl_target = (ifp->Opcode() == prev_op) ?     idom : top;
1604 
1605     // For each child of an IfTrue/IfFalse projection, reroute.
1606     // Loop ends when projection has no more uses.
1607     for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1608       Node* s = ifp->last_out(j);   // Get child of IfTrue/IfFalse
1609       if( !s->depends_only_on_test() ) {
1610         // Find the control input matching this def-use edge.
1611         // For Regions it may not be in slot 0.
1612         uint l;
1613         for( l = 0; s->in(l) != ifp; l++ ) { }
1614         igvn->replace_input_of(s, l, ctrl_target);
1615       } else {                      // Else, for control producers,
1616         igvn->replace_input_of(s, 0, data_target); // Move child to data-target
1617       }
1618     } // End for each child of a projection
1619 
1620     igvn->remove_dead_node(ifp);
1621   } // End for each IfTrue/IfFalse child of If
1622 
1623   // Kill the IfNode
1624   igvn->remove_dead_node(this);
1625 }
1626 
1627 //------------------------------Identity---------------------------------------
1628 // If the test is constant & we match, then we are the input Control
1629 Node *IfProjNode::Identity(PhaseTransform *phase) {
1630   // Can only optimize if cannot go the other way
1631   const TypeTuple *t = phase->type(in(0))->is_tuple();
1632   if (t == TypeTuple::IFNEITHER ||
1633       // kill dead branch first otherwise the IfNode's control will
1634       // have 2 control uses (the IfNode that doesn't go away because
1635       // it still has uses and this branch of the
1636       // If). Node::has_special_unique_user() will cause this node to
1637       // be reprocessed once the dead branch is killed.
1638       (always_taken(t) && in(0)->outcnt() == 1)) {
1639     // IfNode control
1640     return in(0)->in(0);
1641   }
1642   // no progress
1643   return this;
1644 }
1645 
1646 #ifndef PRODUCT
1647 //-------------------------------related---------------------------------------
1648 // An IfProjNode's related node set consists of its input (an IfNode) including
1649 // the IfNode's condition, plus all of its outputs at level 1. In compact mode,
1650 // the restrictions for IfNode apply (see IfNode::rel).
1651 void IfProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
1652   Node* ifNode = this->in(0);
1653   in_rel->append(ifNode);
1654   if (compact) {
1655     ifNode->collect_nodes(in_rel, 3, false, true);
1656   } else {
1657     ifNode->collect_nodes_in_all_data(in_rel, false);
1658   }
1659   this->collect_nodes(out_rel, -1, false, false);
1660 }
1661 
1662 //------------------------------dump_spec--------------------------------------
1663 void IfNode::dump_spec(outputStream *st) const {
1664   st->print("P=%f, C=%f",_prob,_fcnt);
1665 }
1666 
1667 //-------------------------------related---------------------------------------
1668 // For an IfNode, the set of related output nodes is just the output nodes till
1669 // depth 2, i.e, the IfTrue/IfFalse projection nodes plus the nodes they refer.
1670 // The related input nodes contain no control nodes, but all data nodes
1671 // pertaining to the condition. In compact mode, the input nodes are collected
1672 // up to a depth of 3.
1673 void IfNode::related(GrowableArray <Node *> *in_rel, GrowableArray <Node *> *out_rel, bool compact) const {
1674   if (compact) {
1675     this->collect_nodes(in_rel, 3, false, true);
1676   } else {
1677     this->collect_nodes_in_all_data(in_rel, false);
1678   }
1679   this->collect_nodes(out_rel, -2, false, false);
1680 }
1681 #endif
1682 
1683 //------------------------------idealize_test----------------------------------
1684 // Try to canonicalize tests better.  Peek at the Cmp/Bool/If sequence and
1685 // come up with a canonical sequence.  Bools getting 'eq', 'gt' and 'ge' forms
1686 // converted to 'ne', 'le' and 'lt' forms.  IfTrue/IfFalse get swapped as
1687 // needed.
1688 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) {
1689   assert(iff->in(0) != NULL, "If must be live");
1690 
1691   if (iff->outcnt() != 2)  return NULL; // Malformed projections.
1692   Node* old_if_f = iff->proj_out(false);
1693   Node* old_if_t = iff->proj_out(true);
1694 
1695   // CountedLoopEnds want the back-control test to be TRUE, irregardless of
1696   // whether they are testing a 'gt' or 'lt' condition.  The 'gt' condition
1697   // happens in count-down loops
1698   if (iff->is_CountedLoopEnd())  return NULL;
1699   if (!iff->in(1)->is_Bool())  return NULL; // Happens for partially optimized IF tests
1700   BoolNode *b = iff->in(1)->as_Bool();
1701   BoolTest bt = b->_test;
1702   // Test already in good order?
1703   if( bt.is_canonical() )
1704     return NULL;
1705 
1706   // Flip test to be canonical.  Requires flipping the IfFalse/IfTrue and
1707   // cloning the IfNode.
1708   Node* new_b = phase->transform( new BoolNode(b->in(1), bt.negate()) );
1709   if( !new_b->is_Bool() ) return NULL;
1710   b = new_b->as_Bool();
1711 
1712   PhaseIterGVN *igvn = phase->is_IterGVN();
1713   assert( igvn, "Test is not canonical in parser?" );
1714 
1715   // The IF node never really changes, but it needs to be cloned
1716   iff = new IfNode( iff->in(0), b, 1.0-iff->_prob, iff->_fcnt);
1717 
1718   Node *prior = igvn->hash_find_insert(iff);
1719   if( prior ) {
1720     igvn->remove_dead_node(iff);
1721     iff = (IfNode*)prior;
1722   } else {
1723     // Cannot call transform on it just yet
1724     igvn->set_type_bottom(iff);
1725   }
1726   igvn->_worklist.push(iff);
1727 
1728   // Now handle projections.  Cloning not required.
1729   Node* new_if_f = (Node*)(new IfFalseNode( iff ));
1730   Node* new_if_t = (Node*)(new IfTrueNode ( iff ));
1731 
1732   igvn->register_new_node_with_optimizer(new_if_f);
1733   igvn->register_new_node_with_optimizer(new_if_t);
1734   // Flip test, so flip trailing control
1735   igvn->replace_node(old_if_f, new_if_t);
1736   igvn->replace_node(old_if_t, new_if_f);
1737 
1738   // Progress
1739   return iff;
1740 }