1 /*
   2  * Copyright (c) 2000, 2023, 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 "memory/resourceArea.hpp"
  29 #include "opto/addnode.hpp"
  30 #include "opto/castnode.hpp"
  31 #include "opto/cfgnode.hpp"
  32 #include "opto/connode.hpp"
  33 #include "opto/loopnode.hpp"
  34 #include "opto/phaseX.hpp"
  35 #include "opto/predicates.hpp"
  36 #include "opto/runtime.hpp"
  37 #include "opto/rootnode.hpp"
  38 #include "opto/subnode.hpp"
  39 #include "opto/subtypenode.hpp"
  40 
  41 // Portions of code courtesy of Clifford Click
  42 
  43 // Optimization - Graph Style
  44 
  45 
  46 #ifndef PRODUCT
  47 extern uint explicit_null_checks_elided;
  48 #endif
  49 
  50 //=============================================================================
  51 //------------------------------Value------------------------------------------
  52 // Return a tuple for whichever arm of the IF is reachable
  53 const Type* IfNode::Value(PhaseGVN* phase) const {
  54   if( !in(0) ) return Type::TOP;
  55   if( phase->type(in(0)) == Type::TOP )
  56     return Type::TOP;
  57   const Type *t = phase->type(in(1));
  58   if( t == Type::TOP )          // data is undefined
  59     return TypeTuple::IFNEITHER; // unreachable altogether
  60   if( t == TypeInt::ZERO )      // zero, or false
  61     return TypeTuple::IFFALSE;  // only false branch is reachable
  62   if( t == TypeInt::ONE )       // 1, or true
  63     return TypeTuple::IFTRUE;   // only true branch is reachable
  64   assert( t == TypeInt::BOOL, "expected boolean type" );
  65 
  66   return TypeTuple::IFBOTH;     // No progress
  67 }
  68 
  69 const RegMask &IfNode::out_RegMask() const {
  70   return RegMask::Empty;
  71 }
  72 
  73 //------------------------------split_if---------------------------------------
  74 // Look for places where we merge constants, then test on the merged value.
  75 // If the IF test will be constant folded on the path with the constant, we
  76 // win by splitting the IF to before the merge point.
  77 static Node* split_if(IfNode *iff, PhaseIterGVN *igvn) {
  78   // I could be a lot more general here, but I'm trying to squeeze this
  79   // in before the Christmas '98 break so I'm gonna be kinda restrictive
  80   // on the patterns I accept.  CNC
  81 
  82   // Look for a compare of a constant and a merged value
  83   Node *i1 = iff->in(1);
  84   if( !i1->is_Bool() ) return nullptr;
  85   BoolNode *b = i1->as_Bool();
  86   Node *cmp = b->in(1);
  87   if( !cmp->is_Cmp() ) return nullptr;
  88   i1 = cmp->in(1);
  89   if( i1 == nullptr || !i1->is_Phi() ) return nullptr;
  90   PhiNode *phi = i1->as_Phi();
  91   Node *con2 = cmp->in(2);
  92   if( !con2->is_Con() ) return nullptr;
  93   // See that the merge point contains some constants
  94   Node *con1=nullptr;
  95   uint i4;
  96   RegionNode* phi_region = phi->region();
  97   for (i4 = 1; i4 < phi->req(); i4++ ) {
  98     con1 = phi->in(i4);
  99     // Do not optimize partially collapsed merges
 100     if (con1 == nullptr || phi_region->in(i4) == nullptr || igvn->type(phi_region->in(i4)) == Type::TOP) {
 101       igvn->_worklist.push(iff);
 102       return nullptr;
 103     }
 104     if( con1->is_Con() ) break; // Found a constant
 105     // Also allow null-vs-not-null checks
 106     const TypePtr *tp = igvn->type(con1)->isa_ptr();
 107     if( tp && tp->_ptr == TypePtr::NotNull )
 108       break;
 109   }
 110   if( i4 >= phi->req() ) return nullptr; // Found no constants
 111 
 112   igvn->C->set_has_split_ifs(true); // Has chance for split-if
 113 
 114   // Make sure that the compare can be constant folded away
 115   Node *cmp2 = cmp->clone();
 116   cmp2->set_req(1,con1);
 117   cmp2->set_req(2,con2);
 118   const Type *t = cmp2->Value(igvn);
 119   // This compare is dead, so whack it!
 120   igvn->remove_dead_node(cmp2);
 121   if( !t->singleton() ) return nullptr;
 122 
 123   // No intervening control, like a simple Call
 124   Node* r = iff->in(0);
 125   if (!r->is_Region() || r->is_Loop() || phi_region != r || r->as_Region()->is_copy()) {
 126     return nullptr;
 127   }
 128 
 129   // No other users of the cmp/bool
 130   if (b->outcnt() != 1 || cmp->outcnt() != 1) {
 131     //tty->print_cr("many users of cmp/bool");
 132     return nullptr;
 133   }
 134 
 135   // Make sure we can determine where all the uses of merged values go
 136   for (DUIterator_Fast jmax, j = r->fast_outs(jmax); j < jmax; j++) {
 137     Node* u = r->fast_out(j);
 138     if( u == r ) continue;
 139     if( u == iff ) continue;
 140     if( u->outcnt() == 0 ) continue; // use is dead & ignorable
 141     if( !u->is_Phi() ) {
 142       /*
 143       if( u->is_Start() ) {
 144         tty->print_cr("Region has inlined start use");
 145       } else {
 146         tty->print_cr("Region has odd use");
 147         u->dump(2);
 148       }*/
 149       return nullptr;
 150     }
 151     if( u != phi ) {
 152       // CNC - do not allow any other merged value
 153       //tty->print_cr("Merging another value");
 154       //u->dump(2);
 155       return nullptr;
 156     }
 157     // Make sure we can account for all Phi uses
 158     for (DUIterator_Fast kmax, k = u->fast_outs(kmax); k < kmax; k++) {
 159       Node* v = u->fast_out(k); // User of the phi
 160       // CNC - Allow only really simple patterns.
 161       // In particular I disallow AddP of the Phi, a fairly common pattern
 162       if (v == cmp) continue;  // The compare is OK
 163       if (v->is_ConstraintCast()) {
 164         // If the cast is derived from data flow edges, it may not have a control edge.
 165         // If so, it should be safe to split. But follow-up code can not deal with
 166         // this (l. 359). So skip.
 167         if (v->in(0) == nullptr) {
 168           return nullptr;
 169         }
 170         if (v->in(0)->in(0) == iff) {
 171           continue;               // CastPP/II of the IfNode is OK
 172         }
 173       }
 174       // Disabled following code because I cannot tell if exactly one
 175       // path dominates without a real dominator check. CNC 9/9/1999
 176       //uint vop = v->Opcode();
 177       //if( vop == Op_Phi ) {        // Phi from another merge point might be OK
 178       //  Node *r = v->in(0);        // Get controlling point
 179       //  if( !r ) return nullptr;   // Degraded to a copy
 180       //  // Find exactly one path in (either True or False doms, but not IFF)
 181       //  int cnt = 0;
 182       //  for( uint i = 1; i < r->req(); i++ )
 183       //    if( r->in(i) && r->in(i)->in(0) == iff )
 184       //      cnt++;
 185       //  if( cnt == 1 ) continue; // Exactly one of True or False guards Phi
 186       //}
 187       if( !v->is_Call() ) {
 188         /*
 189         if( v->Opcode() == Op_AddP ) {
 190           tty->print_cr("Phi has AddP use");
 191         } else if( v->Opcode() == Op_CastPP ) {
 192           tty->print_cr("Phi has CastPP use");
 193         } else if( v->Opcode() == Op_CastII ) {
 194           tty->print_cr("Phi has CastII use");
 195         } else {
 196           tty->print_cr("Phi has use I can't be bothered with");
 197         }
 198         */
 199       }
 200       return nullptr;
 201 
 202       /* CNC - Cut out all the fancy acceptance tests
 203       // Can we clone this use when doing the transformation?
 204       // If all uses are from Phis at this merge or constants, then YES.
 205       if( !v->in(0) && v != cmp ) {
 206         tty->print_cr("Phi has free-floating use");
 207         v->dump(2);
 208         return nullptr;
 209       }
 210       for( uint l = 1; l < v->req(); l++ ) {
 211         if( (!v->in(l)->is_Phi() || v->in(l)->in(0) != r) &&
 212             !v->in(l)->is_Con() ) {
 213           tty->print_cr("Phi has use");
 214           v->dump(2);
 215           return nullptr;
 216         } // End of if Phi-use input is neither Phi nor Constant
 217       } // End of for all inputs to Phi-use
 218       */
 219     } // End of for all uses of Phi
 220   } // End of for all uses of Region
 221 
 222   // Only do this if the IF node is in a sane state
 223   if (iff->outcnt() != 2)
 224     return nullptr;
 225 
 226   // Got a hit!  Do the Mondo Hack!
 227   //
 228   //ABC  a1c   def   ghi            B     1     e     h   A C   a c   d f   g i
 229   // R - Phi - Phi - Phi            Rc - Phi - Phi - Phi   Rx - Phi - Phi - Phi
 230   //     cmp - 2                         cmp - 2               cmp - 2
 231   //       bool                            bool_c                bool_x
 232   //       if                               if_c                  if_x
 233   //      T  F                              T  F                  T  F
 234   // ..s..    ..t ..                   ..s..    ..t..        ..s..    ..t..
 235   //
 236   // Split the paths coming into the merge point into 2 separate groups of
 237   // merges.  On the left will be all the paths feeding constants into the
 238   // Cmp's Phi.  On the right will be the remaining paths.  The Cmp's Phi
 239   // will fold up into a constant; this will let the Cmp fold up as well as
 240   // all the control flow.  Below the original IF we have 2 control
 241   // dependent regions, 's' and 't'.  Now we will merge the two paths
 242   // just prior to 's' and 't' from the two IFs.  At least 1 path (and quite
 243   // likely 2 or more) will promptly constant fold away.
 244   PhaseGVN *phase = igvn;
 245 
 246   // Make a region merging constants and a region merging the rest
 247   uint req_c = 0;
 248   for (uint ii = 1; ii < r->req(); ii++) {
 249     if (phi->in(ii) == con1) {
 250       req_c++;
 251     }
 252     if (Node::may_be_loop_entry(r->in(ii))) {
 253       // Bail out if splitting through a region with a Parse Predicate input (could
 254       // also be a loop header before loop opts creates a LoopNode for it).
 255       return nullptr;
 256     }
 257   }
 258 
 259   // If all the defs of the phi are the same constant, we already have the desired end state.
 260   // Skip the split that would create empty phi and region nodes.
 261   if ((r->req() - req_c) == 1) {
 262     return nullptr;
 263   }
 264 
 265   // At this point we know that we can apply the split if optimization. If the region is still on the worklist,
 266   // we should wait until it is processed. The region might be removed which makes this optimization redundant.
 267   // This also avoids the creation of dead data loops when rewiring data nodes below when a region is dying.
 268   if (igvn->_worklist.member(r)) {
 269     igvn->_worklist.push(iff); // retry split if later again
 270     return nullptr;
 271   }
 272 
 273   Node *region_c = new RegionNode(req_c + 1);
 274   Node *phi_c    = con1;
 275   uint  len      = r->req();
 276   Node *region_x = new RegionNode(len - req_c);
 277   Node *phi_x    = PhiNode::make_blank(region_x, phi);
 278   for (uint i = 1, i_c = 1, i_x = 1; i < len; i++) {
 279     if (phi->in(i) == con1) {
 280       region_c->init_req( i_c++, r  ->in(i) );
 281     } else {
 282       region_x->init_req( i_x,   r  ->in(i) );
 283       phi_x   ->init_req( i_x++, phi->in(i) );
 284     }
 285   }
 286 
 287   // Register the new RegionNodes but do not transform them.  Cannot
 288   // transform until the entire Region/Phi conglomerate has been hacked
 289   // as a single huge transform.
 290   igvn->register_new_node_with_optimizer( region_c );
 291   igvn->register_new_node_with_optimizer( region_x );
 292   // Prevent the untimely death of phi_x.  Currently he has no uses.  He is
 293   // about to get one.  If this only use goes away, then phi_x will look dead.
 294   // However, he will be picking up some more uses down below.
 295   Node *hook = new Node(4);
 296   hook->init_req(0, phi_x);
 297   hook->init_req(1, phi_c);
 298   phi_x = phase->transform( phi_x );
 299 
 300   // Make the compare
 301   Node *cmp_c = phase->makecon(t);
 302   Node *cmp_x = cmp->clone();
 303   cmp_x->set_req(1,phi_x);
 304   cmp_x->set_req(2,con2);
 305   cmp_x = phase->transform(cmp_x);
 306   // Make the bool
 307   Node *b_c = phase->transform(new BoolNode(cmp_c,b->_test._test));
 308   Node *b_x = phase->transform(new BoolNode(cmp_x,b->_test._test));
 309   // Make the IfNode
 310   IfNode* iff_c = iff->clone()->as_If();
 311   iff_c->set_req(0, region_c);
 312   iff_c->set_req(1, b_c);
 313   igvn->set_type_bottom(iff_c);
 314   igvn->_worklist.push(iff_c);
 315   hook->init_req(2, iff_c);
 316 
 317   IfNode* iff_x = iff->clone()->as_If();
 318   iff_x->set_req(0, region_x);
 319   iff_x->set_req(1, b_x);
 320   igvn->set_type_bottom(iff_x);
 321   igvn->_worklist.push(iff_x);
 322   hook->init_req(3, iff_x);
 323 
 324   // Make the true/false arms
 325   Node *iff_c_t = phase->transform(new IfTrueNode (iff_c));
 326   Node *iff_c_f = phase->transform(new IfFalseNode(iff_c));
 327   Node *iff_x_t = phase->transform(new IfTrueNode (iff_x));
 328   Node *iff_x_f = phase->transform(new IfFalseNode(iff_x));
 329 
 330   // Merge the TRUE paths
 331   Node *region_s = new RegionNode(3);
 332   igvn->_worklist.push(region_s);
 333   region_s->init_req(1, iff_c_t);
 334   region_s->init_req(2, iff_x_t);
 335   igvn->register_new_node_with_optimizer( region_s );
 336 
 337   // Merge the FALSE paths
 338   Node *region_f = new RegionNode(3);
 339   igvn->_worklist.push(region_f);
 340   region_f->init_req(1, iff_c_f);
 341   region_f->init_req(2, iff_x_f);
 342   igvn->register_new_node_with_optimizer( region_f );
 343 
 344   igvn->hash_delete(cmp);// Remove soon-to-be-dead node from hash table.
 345   cmp->set_req(1,nullptr);  // Whack the inputs to cmp because it will be dead
 346   cmp->set_req(2,nullptr);
 347   // Check for all uses of the Phi and give them a new home.
 348   // The 'cmp' got cloned, but CastPP/IIs need to be moved.
 349   Node *phi_s = nullptr;     // do not construct unless needed
 350   Node *phi_f = nullptr;     // do not construct unless needed
 351   for (DUIterator_Last i2min, i2 = phi->last_outs(i2min); i2 >= i2min; --i2) {
 352     Node* v = phi->last_out(i2);// User of the phi
 353     igvn->rehash_node_delayed(v); // Have to fixup other Phi users
 354     uint vop = v->Opcode();
 355     Node *proj = nullptr;
 356     if( vop == Op_Phi ) {       // Remote merge point
 357       Node *r = v->in(0);
 358       for (uint i3 = 1; i3 < r->req(); i3++)
 359         if (r->in(i3) && r->in(i3)->in(0) == iff) {
 360           proj = r->in(i3);
 361           break;
 362         }
 363     } else if( v->is_ConstraintCast() ) {
 364       proj = v->in(0);          // Controlling projection
 365     } else {
 366       assert( 0, "do not know how to handle this guy" );
 367     }
 368     guarantee(proj != nullptr, "sanity");
 369 
 370     Node *proj_path_data, *proj_path_ctrl;
 371     if( proj->Opcode() == Op_IfTrue ) {
 372       if( phi_s == nullptr ) {
 373         // Only construct phi_s if needed, otherwise provides
 374         // interfering use.
 375         phi_s = PhiNode::make_blank(region_s,phi);
 376         phi_s->init_req( 1, phi_c );
 377         phi_s->init_req( 2, phi_x );
 378         hook->add_req(phi_s);
 379         phi_s = phase->transform(phi_s);
 380       }
 381       proj_path_data = phi_s;
 382       proj_path_ctrl = region_s;
 383     } else {
 384       if( phi_f == nullptr ) {
 385         // Only construct phi_f if needed, otherwise provides
 386         // interfering use.
 387         phi_f = PhiNode::make_blank(region_f,phi);
 388         phi_f->init_req( 1, phi_c );
 389         phi_f->init_req( 2, phi_x );
 390         hook->add_req(phi_f);
 391         phi_f = phase->transform(phi_f);
 392       }
 393       proj_path_data = phi_f;
 394       proj_path_ctrl = region_f;
 395     }
 396 
 397     // Fixup 'v' for for the split
 398     if( vop == Op_Phi ) {       // Remote merge point
 399       uint i;
 400       for( i = 1; i < v->req(); i++ )
 401         if( v->in(i) == phi )
 402           break;
 403       v->set_req(i, proj_path_data );
 404     } else if( v->is_ConstraintCast() ) {
 405       v->set_req(0, proj_path_ctrl );
 406       v->set_req(1, proj_path_data );
 407     } else
 408       ShouldNotReachHere();
 409   }
 410 
 411   // Now replace the original iff's True/False with region_s/region_t.
 412   // This makes the original iff go dead.
 413   for (DUIterator_Last i3min, i3 = iff->last_outs(i3min); i3 >= i3min; --i3) {
 414     Node* p = iff->last_out(i3);
 415     assert( p->Opcode() == Op_IfTrue || p->Opcode() == Op_IfFalse, "" );
 416     Node *u = (p->Opcode() == Op_IfTrue) ? region_s : region_f;
 417     // Replace p with u
 418     igvn->add_users_to_worklist(p);
 419     for (DUIterator_Last lmin, l = p->last_outs(lmin); l >= lmin;) {
 420       Node* x = p->last_out(l);
 421       igvn->hash_delete(x);
 422       uint uses_found = 0;
 423       for( uint j = 0; j < x->req(); j++ ) {
 424         if( x->in(j) == p ) {
 425           x->set_req(j, u);
 426           uses_found++;
 427         }
 428       }
 429       l -= uses_found;    // we deleted 1 or more copies of this edge
 430     }
 431     igvn->remove_dead_node(p);
 432   }
 433 
 434   // Force the original merge dead
 435   igvn->hash_delete(r);
 436   // First, remove region's dead users.
 437   for (DUIterator_Last lmin, l = r->last_outs(lmin); l >= lmin;) {
 438     Node* u = r->last_out(l);
 439     if( u == r ) {
 440       r->set_req(0, nullptr);
 441     } else {
 442       assert(u->outcnt() == 0, "only dead users");
 443       igvn->remove_dead_node(u);
 444     }
 445     l -= 1;
 446   }
 447   igvn->remove_dead_node(r);
 448 
 449   // Now remove the bogus extra edges used to keep things alive
 450   igvn->remove_dead_node( hook );
 451 
 452   // Must return either the original node (now dead) or a new node
 453   // (Do not return a top here, since that would break the uniqueness of top.)
 454   return new ConINode(TypeInt::ZERO);
 455 }
 456 
 457 IfNode* IfNode::make_with_same_profile(IfNode* if_node_profile, Node* ctrl, BoolNode* bol) {
 458   // Assert here that we only try to create a clone from an If node with the same profiling if that actually makes sense.
 459   // Some If node subtypes should not be cloned in this way. In theory, we should not clone BaseCountedLoopEndNodes.
 460   // But they can end up being used as normal If nodes when peeling a loop - they serve as zero-trip guard.
 461   // Allow them as well.
 462   assert(if_node_profile->Opcode() == Op_If || if_node_profile->is_RangeCheck()
 463          || if_node_profile->is_BaseCountedLoopEnd(), "should not clone other nodes");
 464   if (if_node_profile->is_RangeCheck()) {
 465     // RangeCheck nodes could be further optimized.
 466     return new RangeCheckNode(ctrl, bol, if_node_profile->_prob, if_node_profile->_fcnt);
 467   } else {
 468     // Not a RangeCheckNode? Fall back to IfNode.
 469     return new IfNode(ctrl, bol, if_node_profile->_prob, if_node_profile->_fcnt);
 470   }
 471 }
 472 
 473 // if this IfNode follows a range check pattern return the projection
 474 // for the failed path
 475 ProjNode* IfNode::range_check_trap_proj(int& flip_test, Node*& l, Node*& r) {
 476   if (outcnt() != 2) {
 477     return nullptr;
 478   }
 479   Node* b = in(1);
 480   if (b == nullptr || !b->is_Bool())  return nullptr;
 481   BoolNode* bn = b->as_Bool();
 482   Node* cmp = bn->in(1);
 483   if (cmp == nullptr)  return nullptr;
 484   if (cmp->Opcode() != Op_CmpU)  return nullptr;
 485 
 486   l = cmp->in(1);
 487   r = cmp->in(2);
 488   flip_test = 1;
 489   if (bn->_test._test == BoolTest::le) {
 490     l = cmp->in(2);
 491     r = cmp->in(1);
 492     flip_test = 2;
 493   } else if (bn->_test._test != BoolTest::lt) {
 494     return nullptr;
 495   }
 496   if (l->is_top())  return nullptr;   // Top input means dead test
 497   if (r->Opcode() != Op_LoadRange && !is_RangeCheck())  return nullptr;
 498 
 499   // We have recognized one of these forms:
 500   //  Flip 1:  If (Bool[<] CmpU(l, LoadRange)) ...
 501   //  Flip 2:  If (Bool[<=] CmpU(LoadRange, l)) ...
 502 
 503   ProjNode* iftrap = proj_out_or_null(flip_test == 2 ? true : false);
 504   return iftrap;
 505 }
 506 
 507 
 508 //------------------------------is_range_check---------------------------------
 509 // Return 0 if not a range check.  Return 1 if a range check and set index and
 510 // offset.  Return 2 if we had to negate the test.  Index is null if the check
 511 // is versus a constant.
 512 int RangeCheckNode::is_range_check(Node* &range, Node* &index, jint &offset) {
 513   int flip_test = 0;
 514   Node* l = nullptr;
 515   Node* r = nullptr;
 516   ProjNode* iftrap = range_check_trap_proj(flip_test, l, r);
 517 
 518   if (iftrap == nullptr) {
 519     return 0;
 520   }
 521 
 522   // Make sure it's a real range check by requiring an uncommon trap
 523   // along the OOB path.  Otherwise, it's possible that the user wrote
 524   // something which optimized to look like a range check but behaves
 525   // in some other way.
 526   if (iftrap->is_uncommon_trap_proj(Deoptimization::Reason_range_check) == nullptr) {
 527     return 0;
 528   }
 529 
 530   // Look for index+offset form
 531   Node* ind = l;
 532   jint  off = 0;
 533   if (l->is_top()) {
 534     return 0;
 535   } else if (l->Opcode() == Op_AddI) {
 536     if ((off = l->in(1)->find_int_con(0)) != 0) {
 537       ind = l->in(2)->uncast();
 538     } else if ((off = l->in(2)->find_int_con(0)) != 0) {
 539       ind = l->in(1)->uncast();
 540     }
 541   } else if ((off = l->find_int_con(-1)) >= 0) {
 542     // constant offset with no variable index
 543     ind = nullptr;
 544   } else {
 545     // variable index with no constant offset (or dead negative index)
 546     off = 0;
 547   }
 548 
 549   // Return all the values:
 550   index  = ind;
 551   offset = off;
 552   range  = r;
 553   return flip_test;
 554 }
 555 
 556 //------------------------------adjust_check-----------------------------------
 557 // Adjust (widen) a prior range check
 558 static void adjust_check(IfProjNode* proj, Node* range, Node* index,
 559                          int flip, jint off_lo, PhaseIterGVN* igvn) {
 560   PhaseGVN *gvn = igvn;
 561   // Break apart the old check
 562   Node *iff = proj->in(0);
 563   Node *bol = iff->in(1);
 564   if( bol->is_top() ) return;   // In case a partially dead range check appears
 565   // bail (or bomb[ASSERT/DEBUG]) if NOT projection-->IfNode-->BoolNode
 566   DEBUG_ONLY( if (!bol->is_Bool()) { proj->dump(3); fatal("Expect projection-->IfNode-->BoolNode"); } )
 567   if (!bol->is_Bool()) return;
 568 
 569   Node *cmp = bol->in(1);
 570   // Compute a new check
 571   Node *new_add = gvn->intcon(off_lo);
 572   if (index) {
 573     new_add = off_lo ? gvn->transform(new AddINode(index, new_add)) : index;
 574   }
 575   Node *new_cmp = (flip == 1)
 576     ? new CmpUNode(new_add, range)
 577     : new CmpUNode(range, new_add);
 578   new_cmp = gvn->transform(new_cmp);
 579   // See if no need to adjust the existing check
 580   if (new_cmp == cmp) return;
 581   // Else, adjust existing check
 582   Node* new_bol = gvn->transform(new BoolNode(new_cmp, bol->as_Bool()->_test._test));
 583   igvn->rehash_node_delayed(iff);
 584   iff->set_req_X(1, new_bol, igvn);
 585   // As part of range check smearing, this range check is widened. Loads and range check Cast nodes that are control
 586   // dependent on this range check now depend on multiple dominating range checks. These control dependent nodes end up
 587   // at the lowest/nearest dominating check in the graph. To ensure that these Loads/Casts do not float above any of the
 588   // dominating checks (even when the lowest dominating check is later replaced by yet another dominating check), we
 589   // need to pin them at the lowest dominating check.
 590   proj->pin_array_access_nodes(igvn);
 591 }
 592 
 593 //------------------------------up_one_dom-------------------------------------
 594 // Walk up the dominator tree one step.  Return null at root or true
 595 // complex merges.  Skips through small diamonds.
 596 Node* IfNode::up_one_dom(Node *curr, bool linear_only) {
 597   Node *dom = curr->in(0);
 598   if( !dom )                    // Found a Region degraded to a copy?
 599     return curr->nonnull_req(); // Skip thru it
 600 
 601   if( curr != dom )             // Normal walk up one step?
 602     return dom;
 603 
 604   // Use linear_only if we are still parsing, since we cannot
 605   // trust the regions to be fully filled in.
 606   if (linear_only)
 607     return nullptr;
 608 
 609   if( dom->is_Root() )
 610     return nullptr;
 611 
 612   // Else hit a Region.  Check for a loop header
 613   if( dom->is_Loop() )
 614     return dom->in(1);          // Skip up thru loops
 615 
 616   // Check for small diamonds
 617   Node *din1, *din2, *din3, *din4;
 618   if( dom->req() == 3 &&        // 2-path merge point
 619       (din1 = dom ->in(1)) &&   // Left  path exists
 620       (din2 = dom ->in(2)) &&   // Right path exists
 621       (din3 = din1->in(0)) &&   // Left  path up one
 622       (din4 = din2->in(0)) ) {  // Right path up one
 623     if( din3->is_Call() &&      // Handle a slow-path call on either arm
 624         (din3 = din3->in(0)) )
 625       din3 = din3->in(0);
 626     if( din4->is_Call() &&      // Handle a slow-path call on either arm
 627         (din4 = din4->in(0)) )
 628       din4 = din4->in(0);
 629     if (din3 != nullptr && din3 == din4 && din3->is_If()) // Regions not degraded to a copy
 630       return din3;              // Skip around diamonds
 631   }
 632 
 633   // Give up the search at true merges
 634   return nullptr;                  // Dead loop?  Or hit root?
 635 }
 636 
 637 
 638 //------------------------------filtered_int_type--------------------------------
 639 // Return a possibly more restrictive type for val based on condition control flow for an if
 640 const TypeInt* IfNode::filtered_int_type(PhaseGVN* gvn, Node* val, Node* if_proj) {
 641   assert(if_proj &&
 642          (if_proj->Opcode() == Op_IfTrue || if_proj->Opcode() == Op_IfFalse), "expecting an if projection");
 643   if (if_proj->in(0) && if_proj->in(0)->is_If()) {
 644     IfNode* iff = if_proj->in(0)->as_If();
 645     if (iff->in(1) && iff->in(1)->is_Bool()) {
 646       BoolNode* bol = iff->in(1)->as_Bool();
 647       if (bol->in(1) && bol->in(1)->is_Cmp()) {
 648         const CmpNode* cmp  = bol->in(1)->as_Cmp();
 649         if (cmp->in(1) == val) {
 650           const TypeInt* cmp2_t = gvn->type(cmp->in(2))->isa_int();
 651           if (cmp2_t != nullptr) {
 652             jint lo = cmp2_t->_lo;
 653             jint hi = cmp2_t->_hi;
 654             BoolTest::mask msk = if_proj->Opcode() == Op_IfTrue ? bol->_test._test : bol->_test.negate();
 655             switch (msk) {
 656             case BoolTest::ne: {
 657               // If val is compared to its lower or upper bound, we can narrow the type
 658               const TypeInt* val_t = gvn->type(val)->isa_int();
 659               if (val_t != nullptr && !val_t->singleton() && cmp2_t->is_con()) {
 660                 if (val_t->_lo == lo) {
 661                   return TypeInt::make(val_t->_lo + 1, val_t->_hi, val_t->_widen);
 662                 } else if (val_t->_hi == hi) {
 663                   return TypeInt::make(val_t->_lo, val_t->_hi - 1, val_t->_widen);
 664                 }
 665               }
 666               // Can't refine type
 667               return nullptr;
 668             }
 669             case BoolTest::eq:
 670               return cmp2_t;
 671             case BoolTest::lt:
 672               lo = TypeInt::INT->_lo;
 673               if (hi != min_jint) {
 674                 hi = hi - 1;
 675               }
 676               break;
 677             case BoolTest::le:
 678               lo = TypeInt::INT->_lo;
 679               break;
 680             case BoolTest::gt:
 681               if (lo != max_jint) {
 682                 lo = lo + 1;
 683               }
 684               hi = TypeInt::INT->_hi;
 685               break;
 686             case BoolTest::ge:
 687               // lo unchanged
 688               hi = TypeInt::INT->_hi;
 689               break;
 690             default:
 691               break;
 692             }
 693             const TypeInt* rtn_t = TypeInt::make(lo, hi, cmp2_t->_widen);
 694             return rtn_t;
 695           }
 696         }
 697       }
 698     }
 699   }
 700   return nullptr;
 701 }
 702 
 703 //------------------------------fold_compares----------------------------
 704 // See if a pair of CmpIs can be converted into a CmpU.  In some cases
 705 // the direction of this if is determined by the preceding if so it
 706 // can be eliminate entirely.
 707 //
 708 // Given an if testing (CmpI n v) check for an immediately control
 709 // dependent if that is testing (CmpI n v2) and has one projection
 710 // leading to this if and the other projection leading to a region
 711 // that merges one of this ifs control projections.
 712 //
 713 //                   If
 714 //                  / |
 715 //                 /  |
 716 //                /   |
 717 //              If    |
 718 //              /\    |
 719 //             /  \   |
 720 //            /    \  |
 721 //           /    Region
 722 //
 723 // Or given an if testing (CmpI n v) check for a dominating if that is
 724 // testing (CmpI n v2), both having one projection leading to an
 725 // uncommon trap. Allow Another independent guard in between to cover
 726 // an explicit range check:
 727 // if (index < 0 || index >= array.length) {
 728 // which may need a null check to guard the LoadRange
 729 //
 730 //                   If
 731 //                  / \
 732 //                 /   \
 733 //                /     \
 734 //              If      unc
 735 //              /\
 736 //             /  \
 737 //            /    \
 738 //           /      unc
 739 //
 740 
 741 // Is the comparison for this If suitable for folding?
 742 bool IfNode::cmpi_folds(PhaseIterGVN* igvn, bool fold_ne) {
 743   return in(1) != nullptr &&
 744     in(1)->is_Bool() &&
 745     in(1)->in(1) != nullptr &&
 746     in(1)->in(1)->Opcode() == Op_CmpI &&
 747     in(1)->in(1)->in(2) != nullptr &&
 748     in(1)->in(1)->in(2) != igvn->C->top() &&
 749     (in(1)->as_Bool()->_test.is_less() ||
 750      in(1)->as_Bool()->_test.is_greater() ||
 751      (fold_ne && in(1)->as_Bool()->_test._test == BoolTest::ne));
 752 }
 753 
 754 // Is a dominating control suitable for folding with this if?
 755 bool IfNode::is_ctrl_folds(Node* ctrl, PhaseIterGVN* igvn) {
 756   return ctrl != nullptr &&
 757     ctrl->is_Proj() &&
 758     ctrl->in(0) != nullptr &&
 759     ctrl->in(0)->Opcode() == Op_If &&
 760     ctrl->in(0)->outcnt() == 2 &&
 761     ctrl->in(0)->as_If()->cmpi_folds(igvn, true) &&
 762     // Must compare same value
 763     ctrl->in(0)->in(1)->in(1)->in(1) != nullptr &&
 764     ctrl->in(0)->in(1)->in(1)->in(1) != igvn->C->top() &&
 765     ctrl->in(0)->in(1)->in(1)->in(1) == in(1)->in(1)->in(1);
 766 }
 767 
 768 // Do this If and the dominating If share a region?
 769 bool IfNode::has_shared_region(ProjNode* proj, ProjNode*& success, ProjNode*& fail) {
 770   ProjNode* otherproj = proj->other_if_proj();
 771   Node* otherproj_ctrl_use = otherproj->unique_ctrl_out_or_null();
 772   RegionNode* region = (otherproj_ctrl_use != nullptr && otherproj_ctrl_use->is_Region()) ? otherproj_ctrl_use->as_Region() : nullptr;
 773   success = nullptr;
 774   fail = nullptr;
 775 
 776   if (otherproj->outcnt() == 1 && region != nullptr && !region->has_phi()) {
 777     for (int i = 0; i < 2; i++) {
 778       ProjNode* proj = proj_out(i);
 779       if (success == nullptr && proj->outcnt() == 1 && proj->unique_out() == region) {
 780         success = proj;
 781       } else if (fail == nullptr) {
 782         fail = proj;
 783       } else {
 784         success = fail = nullptr;
 785       }
 786     }
 787   }
 788   return success != nullptr && fail != nullptr;
 789 }
 790 
 791 bool IfNode::is_dominator_unc(CallStaticJavaNode* dom_unc, CallStaticJavaNode* unc) {
 792   // Different methods and methods containing jsrs are not supported.
 793   ciMethod* method = unc->jvms()->method();
 794   ciMethod* dom_method = dom_unc->jvms()->method();
 795   if (method != dom_method || method->has_jsrs()) {
 796     return false;
 797   }
 798   // Check that both traps are in the same activation of the method (instead
 799   // of two activations being inlined through different call sites) by verifying
 800   // that the call stacks are equal for both JVMStates.
 801   JVMState* dom_caller = dom_unc->jvms()->caller();
 802   JVMState* caller = unc->jvms()->caller();
 803   if ((dom_caller == nullptr) != (caller == nullptr)) {
 804     // The current method must either be inlined into both dom_caller and
 805     // caller or must not be inlined at all (top method). Bail out otherwise.
 806     return false;
 807   } else if (dom_caller != nullptr && !dom_caller->same_calls_as(caller)) {
 808     return false;
 809   }
 810   // Check that the bci of the dominating uncommon trap dominates the bci
 811   // of the dominated uncommon trap. Otherwise we may not re-execute
 812   // the dominated check after deoptimization from the merged uncommon trap.
 813   ciTypeFlow* flow = dom_method->get_flow_analysis();
 814   int bci = unc->jvms()->bci();
 815   int dom_bci = dom_unc->jvms()->bci();
 816   if (!flow->is_dominated_by(bci, dom_bci)) {
 817     return false;
 818   }
 819 
 820   return true;
 821 }
 822 
 823 // Return projection that leads to an uncommon trap if any
 824 ProjNode* IfNode::uncommon_trap_proj(CallStaticJavaNode*& call) const {
 825   for (int i = 0; i < 2; i++) {
 826     call = proj_out(i)->is_uncommon_trap_proj();
 827     if (call != nullptr) {
 828       return proj_out(i);
 829     }
 830   }
 831   return nullptr;
 832 }
 833 
 834 // Do this If and the dominating If both branch out to an uncommon trap
 835 bool IfNode::has_only_uncommon_traps(ProjNode* proj, ProjNode*& success, ProjNode*& fail, PhaseIterGVN* igvn) {
 836   ProjNode* otherproj = proj->other_if_proj();
 837   CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj();
 838 
 839   if (otherproj->outcnt() == 1 && dom_unc != nullptr) {
 840     // We need to re-execute the folded Ifs after deoptimization from the merged traps
 841     if (!dom_unc->jvms()->should_reexecute()) {
 842       return false;
 843     }
 844 
 845     CallStaticJavaNode* unc = nullptr;
 846     ProjNode* unc_proj = uncommon_trap_proj(unc);
 847     if (unc_proj != nullptr && unc_proj->outcnt() == 1) {
 848       if (dom_unc == unc) {
 849         // Allow the uncommon trap to be shared through a region
 850         RegionNode* r = unc->in(0)->as_Region();
 851         if (r->outcnt() != 2 || r->req() != 3 || r->find_edge(otherproj) == -1 || r->find_edge(unc_proj) == -1) {
 852           return false;
 853         }
 854         assert(r->has_phi() == nullptr, "simple region shouldn't have a phi");
 855       } else if (dom_unc->in(0) != otherproj || unc->in(0) != unc_proj) {
 856         return false;
 857       }
 858 
 859       if (!is_dominator_unc(dom_unc, unc)) {
 860         return false;
 861       }
 862 
 863       // See merge_uncommon_traps: the reason of the uncommon trap
 864       // will be changed and the state of the dominating If will be
 865       // used. Checked that we didn't apply this transformation in a
 866       // previous compilation and it didn't cause too many traps
 867       ciMethod* dom_method = dom_unc->jvms()->method();
 868       int dom_bci = dom_unc->jvms()->bci();
 869       if (!igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_unstable_fused_if) &&
 870           !igvn->C->too_many_traps(dom_method, dom_bci, Deoptimization::Reason_range_check) &&
 871           // Return true if c2 manages to reconcile with UnstableIf optimization. See the comments for it.
 872           igvn->C->remove_unstable_if_trap(dom_unc, true/*yield*/)) {
 873         success = unc_proj;
 874         fail = unc_proj->other_if_proj();
 875         return true;
 876       }
 877     }
 878   }
 879   return false;
 880 }
 881 
 882 // Check that the 2 CmpI can be folded into as single CmpU and proceed with the folding
 883 bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
 884   Node* this_cmp = in(1)->in(1);
 885   BoolNode* this_bool = in(1)->as_Bool();
 886   IfNode* dom_iff = proj->in(0)->as_If();
 887   BoolNode* dom_bool = dom_iff->in(1)->as_Bool();
 888   Node* lo = dom_iff->in(1)->in(1)->in(2);
 889   Node* hi = this_cmp->in(2);
 890   Node* n = this_cmp->in(1);
 891   ProjNode* otherproj = proj->other_if_proj();
 892 
 893   const TypeInt* lo_type = IfNode::filtered_int_type(igvn, n, otherproj);
 894   const TypeInt* hi_type = IfNode::filtered_int_type(igvn, n, success);
 895 
 896   BoolTest::mask lo_test = dom_bool->_test._test;
 897   BoolTest::mask hi_test = this_bool->_test._test;
 898   BoolTest::mask cond = hi_test;
 899 
 900   // convert:
 901   //
 902   //          dom_bool = x {<,<=,>,>=} a
 903   //                           / \
 904   //     proj = {True,False}  /   \ otherproj = {False,True}
 905   //                         /
 906   //        this_bool = x {<,<=} b
 907   //                       / \
 908   //  fail = {True,False} /   \ success = {False,True}
 909   //                     /
 910   //
 911   // (Second test guaranteed canonicalized, first one may not have
 912   // been canonicalized yet)
 913   //
 914   // into:
 915   //
 916   // cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim
 917   //                       / \
 918   //                 fail /   \ success
 919   //                     /
 920   //
 921 
 922   // Figure out which of the two tests sets the upper bound and which
 923   // sets the lower bound if any.
 924   Node* adjusted_lim = nullptr;
 925   if (lo_type != nullptr && hi_type != nullptr && hi_type->_lo > lo_type->_hi &&
 926       hi_type->_hi == max_jint && lo_type->_lo == min_jint && lo_test != BoolTest::ne) {
 927     assert((dom_bool->_test.is_less() && !proj->_con) ||
 928            (dom_bool->_test.is_greater() && proj->_con), "incorrect test");
 929 
 930     // this_bool = <
 931     //   dom_bool = >= (proj = True) or dom_bool = < (proj = False)
 932     //     x in [a, b[ on the fail (= True) projection, b > a-1 (because of hi_type->_lo > lo_type->_hi test above):
 933     //     lo = a, hi = b, adjusted_lim = b-a, cond = <u
 934     //   dom_bool = > (proj = True) or dom_bool = <= (proj = False)
 935     //     x in ]a, b[ on the fail (= True) projection, b > a:
 936     //     lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <u
 937     // this_bool = <=
 938     //   dom_bool = >= (proj = True) or dom_bool = < (proj = False)
 939     //     x in [a, b] on the fail (= True) projection, b+1 > a-1:
 940     //     lo = a, hi = b, adjusted_lim = b-a+1, cond = <u
 941     //     lo = a, hi = b, adjusted_lim = b-a, cond = <=u doesn't work because b = a - 1 is possible, then b-a = -1
 942     //   dom_bool = > (proj = True) or dom_bool = <= (proj = False)
 943     //     x in ]a, b] on the fail (= True) projection b+1 > a:
 944     //     lo = a+1, hi = b, adjusted_lim = b-a, cond = <u
 945     //     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
 946 
 947     if (hi_test == BoolTest::lt) {
 948       if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
 949         lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
 950       }
 951     } else if (hi_test == BoolTest::le) {
 952       if (lo_test == BoolTest::ge || lo_test == BoolTest::lt) {
 953         adjusted_lim = igvn->transform(new SubINode(hi, lo));
 954         adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
 955         cond = BoolTest::lt;
 956       } else if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
 957         adjusted_lim = igvn->transform(new SubINode(hi, lo));
 958         lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
 959         cond = BoolTest::lt;
 960       } else {
 961         assert(false, "unhandled lo_test: %d", lo_test);
 962         return false;
 963       }
 964     } else {
 965       assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled hi_test: %d", hi_test);
 966       return false;
 967     }
 968     // this test was canonicalized
 969     assert(this_bool->_test.is_less() && fail->_con, "incorrect test");
 970   } else if (lo_type != nullptr && hi_type != nullptr && lo_type->_lo > hi_type->_hi &&
 971              lo_type->_hi == max_jint && hi_type->_lo == min_jint && lo_test != BoolTest::ne) {
 972 
 973     // this_bool = <
 974     //   dom_bool = < (proj = True) or dom_bool = >= (proj = False)
 975     //     x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above):
 976     //     lo = b, hi = a, adjusted_lim = a-b, cond = >=u
 977     //   dom_bool = <= (proj = True) or dom_bool = > (proj = False)
 978     //     x in [b, a] on the fail (= False) projection, a+1 > b-1:
 979     //     lo = b, hi = a, adjusted_lim = a-b+1, cond = >=u
 980     //     lo = b, hi = a, adjusted_lim = a-b, cond = >u doesn't work because a = b - 1 is possible, then b-a = -1
 981     // this_bool = <=
 982     //   dom_bool = < (proj = True) or dom_bool = >= (proj = False)
 983     //     x in ]b, a[ on the fail (= False) projection, a > b:
 984     //     lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u
 985     //   dom_bool = <= (proj = True) or dom_bool = > (proj = False)
 986     //     x in ]b, a] on the fail (= False) projection, a+1 > b:
 987     //     lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u
 988     //     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
 989 
 990     swap(lo, hi);
 991     swap(lo_type, hi_type);
 992     swap(lo_test, hi_test);
 993 
 994     assert((dom_bool->_test.is_less() && proj->_con) ||
 995            (dom_bool->_test.is_greater() && !proj->_con), "incorrect test");
 996 
 997     cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge;
 998 
 999     if (lo_test == BoolTest::lt) {
1000       if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
1001         cond = BoolTest::ge;
1002       } else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {
1003         adjusted_lim = igvn->transform(new SubINode(hi, lo));
1004         adjusted_lim = igvn->transform(new AddINode(adjusted_lim, igvn->intcon(1)));
1005         cond = BoolTest::ge;
1006       } else {
1007         assert(false, "unhandled hi_test: %d", hi_test);
1008         return false;
1009       }
1010     } else if (lo_test == BoolTest::le) {
1011       if (hi_test == BoolTest::lt || hi_test == BoolTest::ge) {
1012         lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
1013         cond = BoolTest::ge;
1014       } else if (hi_test == BoolTest::le || hi_test == BoolTest::gt) {
1015         adjusted_lim = igvn->transform(new SubINode(hi, lo));
1016         lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
1017         cond = BoolTest::ge;
1018       } else {
1019         assert(false, "unhandled hi_test: %d", hi_test);
1020         return false;
1021       }
1022     } else {
1023       assert(igvn->_worklist.member(in(1)) && in(1)->Value(igvn) != igvn->type(in(1)), "unhandled lo_test: %d", lo_test);
1024       return false;
1025     }
1026     // this test was canonicalized
1027     assert(this_bool->_test.is_less() && !fail->_con, "incorrect test");
1028   } else {
1029     const TypeInt* failtype = filtered_int_type(igvn, n, proj);
1030     if (failtype != nullptr) {
1031       const TypeInt* type2 = filtered_int_type(igvn, n, fail);
1032       if (type2 != nullptr) {
1033         failtype = failtype->join(type2)->is_int();
1034         if (failtype->empty()) {
1035           // previous if determines the result of this if so
1036           // replace Bool with constant
1037           igvn->replace_input_of(this, 1, igvn->intcon(success->_con));
1038           return true;
1039         }
1040       }
1041     }
1042     return false;
1043   }
1044 
1045   assert(lo != nullptr && hi != nullptr, "sanity");
1046   Node* hook = new Node(lo); // Add a use to lo to prevent him from dying
1047   // Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo))
1048   Node* adjusted_val = igvn->transform(new SubINode(n,  lo));
1049   if (adjusted_lim == nullptr) {
1050     adjusted_lim = igvn->transform(new SubINode(hi, lo));
1051   }
1052   hook->destruct(igvn);
1053 
1054   if (adjusted_val->is_top() || adjusted_lim->is_top()) {
1055     return false;
1056   }
1057 
1058   if (igvn->type(adjusted_lim)->is_int()->_lo < 0 &&
1059       !igvn->C->post_loop_opts_phase()) {
1060     // If range check elimination applies to this comparison, it includes code to protect from overflows that may
1061     // cause the main loop to be skipped entirely. Delay this transformation.
1062     // Example:
1063     // for (int i = 0; i < limit; i++) {
1064     //   if (i < max_jint && i > min_jint) {...
1065     // }
1066     // Comparisons folded as:
1067     // i - min_jint - 1 <u -2
1068     // when RC applies, main loop limit becomes:
1069     // min(limit, max(-2 + min_jint + 1, min_jint))
1070     // = min(limit, min_jint)
1071     // = min_jint
1072     if (adjusted_val->outcnt() == 0) {
1073       igvn->remove_dead_node(adjusted_val);
1074     }
1075     if (adjusted_lim->outcnt() == 0) {
1076       igvn->remove_dead_node(adjusted_lim);
1077     }
1078     igvn->C->record_for_post_loop_opts_igvn(this);
1079     return false;
1080   }
1081 
1082   Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim));
1083   Node* newbool = igvn->transform(new BoolNode(newcmp, cond));
1084 
1085   igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con));
1086   igvn->replace_input_of(this, 1, newbool);
1087 
1088   return true;
1089 }
1090 
1091 // Merge the branches that trap for this If and the dominating If into
1092 // a single region that branches to the uncommon trap for the
1093 // dominating If
1094 Node* IfNode::merge_uncommon_traps(ProjNode* proj, ProjNode* success, ProjNode* fail, PhaseIterGVN* igvn) {
1095   Node* res = this;
1096   assert(success->in(0) == this, "bad projection");
1097 
1098   ProjNode* otherproj = proj->other_if_proj();
1099 
1100   CallStaticJavaNode* unc = success->is_uncommon_trap_proj();
1101   CallStaticJavaNode* dom_unc = otherproj->is_uncommon_trap_proj();
1102 
1103   if (unc != dom_unc) {
1104     Node* r = new RegionNode(3);
1105 
1106     r->set_req(1, otherproj);
1107     r->set_req(2, success);
1108     r = igvn->transform(r);
1109     assert(r->is_Region(), "can't go away");
1110 
1111     // Make both If trap at the state of the first If: once the CmpI
1112     // nodes are merged, if we trap we don't know which of the CmpI
1113     // nodes would have caused the trap so we have to restart
1114     // execution at the first one
1115     igvn->replace_input_of(dom_unc, 0, r);
1116     igvn->replace_input_of(unc, 0, igvn->C->top());
1117   }
1118   int trap_request = dom_unc->uncommon_trap_request();
1119   Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1120   Deoptimization::DeoptAction action = Deoptimization::trap_request_action(trap_request);
1121 
1122   int flip_test = 0;
1123   Node* l = nullptr;
1124   Node* r = nullptr;
1125 
1126   if (success->in(0)->as_If()->range_check_trap_proj(flip_test, l, r) != nullptr) {
1127     // If this looks like a range check, change the trap to
1128     // Reason_range_check so the compiler recognizes it as a range
1129     // check and applies the corresponding optimizations
1130     trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_range_check, action);
1131 
1132     improve_address_types(l, r, fail, igvn);
1133 
1134     res = igvn->transform(new RangeCheckNode(in(0), in(1), _prob, _fcnt));
1135   } else if (unc != dom_unc) {
1136     // If we trap we won't know what CmpI would have caused the trap
1137     // so use a special trap reason to mark this pair of CmpI nodes as
1138     // bad candidate for folding. On recompilation we won't fold them
1139     // and we may trap again but this time we'll know what branch
1140     // traps
1141     trap_request = Deoptimization::make_trap_request(Deoptimization::Reason_unstable_fused_if, action);
1142   }
1143   igvn->replace_input_of(dom_unc, TypeFunc::Parms, igvn->intcon(trap_request));
1144   return res;
1145 }
1146 
1147 // If we are turning 2 CmpI nodes into a CmpU that follows the pattern
1148 // of a rangecheck on index i, on 64 bit the compares may be followed
1149 // by memory accesses using i as index. In that case, the CmpU tells
1150 // us something about the values taken by i that can help the compiler
1151 // (see Compile::conv_I2X_index())
1152 void IfNode::improve_address_types(Node* l, Node* r, ProjNode* fail, PhaseIterGVN* igvn) {
1153 #ifdef _LP64
1154   ResourceMark rm;
1155   Node_Stack stack(2);
1156 
1157   assert(r->Opcode() == Op_LoadRange, "unexpected range check");
1158   const TypeInt* array_size = igvn->type(r)->is_int();
1159 
1160   stack.push(l, 0);
1161 
1162   while(stack.size() > 0) {
1163     Node* n = stack.node();
1164     uint start = stack.index();
1165 
1166     uint i = start;
1167     for (; i < n->outcnt(); i++) {
1168       Node* use = n->raw_out(i);
1169       if (stack.size() == 1) {
1170         if (use->Opcode() == Op_ConvI2L) {
1171           const TypeLong* bounds = use->as_Type()->type()->is_long();
1172           if (bounds->_lo <= array_size->_lo && bounds->_hi >= array_size->_hi &&
1173               (bounds->_lo != array_size->_lo || bounds->_hi != array_size->_hi)) {
1174             stack.set_index(i+1);
1175             stack.push(use, 0);
1176             break;
1177           }
1178         }
1179       } else if (use->is_Mem()) {
1180         Node* ctrl = use->in(0);
1181         for (int i = 0; i < 10 && ctrl != nullptr && ctrl != fail; i++) {
1182           ctrl = up_one_dom(ctrl);
1183         }
1184         if (ctrl == fail) {
1185           Node* init_n = stack.node_at(1);
1186           assert(init_n->Opcode() == Op_ConvI2L, "unexpected first node");
1187           // Create a new narrow ConvI2L node that is dependent on the range check
1188           Node* new_n = igvn->C->conv_I2X_index(igvn, l, array_size, fail);
1189 
1190           // The type of the ConvI2L may be widen and so the new
1191           // ConvI2L may not be better than an existing ConvI2L
1192           if (new_n != init_n) {
1193             for (uint j = 2; j < stack.size(); j++) {
1194               Node* n = stack.node_at(j);
1195               Node* clone = n->clone();
1196               int rep = clone->replace_edge(init_n, new_n, igvn);
1197               assert(rep > 0, "can't find expected node?");
1198               clone = igvn->transform(clone);
1199               init_n = n;
1200               new_n = clone;
1201             }
1202             igvn->hash_delete(use);
1203             int rep = use->replace_edge(init_n, new_n, igvn);
1204             assert(rep > 0, "can't find expected node?");
1205             igvn->transform(use);
1206             if (init_n->outcnt() == 0) {
1207               igvn->_worklist.push(init_n);
1208             }
1209           }
1210         }
1211       } else if (use->in(0) == nullptr && (igvn->type(use)->isa_long() ||
1212                                         igvn->type(use)->isa_ptr())) {
1213         stack.set_index(i+1);
1214         stack.push(use, 0);
1215         break;
1216       }
1217     }
1218     if (i == n->outcnt()) {
1219       stack.pop();
1220     }
1221   }
1222 #endif
1223 }
1224 
1225 bool IfNode::is_cmp_with_loadrange(ProjNode* proj) {
1226   if (in(1) != nullptr &&
1227       in(1)->in(1) != nullptr &&
1228       in(1)->in(1)->in(2) != nullptr) {
1229     Node* other = in(1)->in(1)->in(2);
1230     if (other->Opcode() == Op_LoadRange &&
1231         ((other->in(0) != nullptr && other->in(0) == proj) ||
1232          (other->in(0) == nullptr &&
1233           other->in(2) != nullptr &&
1234           other->in(2)->is_AddP() &&
1235           other->in(2)->in(1) != nullptr &&
1236           other->in(2)->in(1)->Opcode() == Op_CastPP &&
1237           other->in(2)->in(1)->in(0) == proj))) {
1238       return true;
1239     }
1240   }
1241   return false;
1242 }
1243 
1244 bool IfNode::is_null_check(ProjNode* proj, PhaseIterGVN* igvn) {
1245   Node* other = in(1)->in(1)->in(2);
1246   if (other->in(MemNode::Address) != nullptr &&
1247       proj->in(0)->in(1) != nullptr &&
1248       proj->in(0)->in(1)->is_Bool() &&
1249       proj->in(0)->in(1)->in(1) != nullptr &&
1250       proj->in(0)->in(1)->in(1)->Opcode() == Op_CmpP &&
1251       proj->in(0)->in(1)->in(1)->in(2) != nullptr &&
1252       proj->in(0)->in(1)->in(1)->in(1) == other->in(MemNode::Address)->in(AddPNode::Address)->uncast() &&
1253       igvn->type(proj->in(0)->in(1)->in(1)->in(2)) == TypePtr::NULL_PTR) {
1254     return true;
1255   }
1256   return false;
1257 }
1258 
1259 // Check that the If that is in between the 2 integer comparisons has
1260 // no side effect
1261 bool IfNode::is_side_effect_free_test(ProjNode* proj, PhaseIterGVN* igvn) {
1262   if (proj == nullptr) {
1263     return false;
1264   }
1265   CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern();
1266   if (unc != nullptr && proj->outcnt() <= 2) {
1267     if (proj->outcnt() == 1 ||
1268         // Allow simple null check from LoadRange
1269         (is_cmp_with_loadrange(proj) && is_null_check(proj, igvn))) {
1270       CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern();
1271       CallStaticJavaNode* dom_unc = proj->in(0)->in(0)->as_Proj()->is_uncommon_trap_if_pattern();
1272       assert(dom_unc != nullptr, "is_uncommon_trap_if_pattern returned null");
1273 
1274       // reroute_side_effect_free_unc changes the state of this
1275       // uncommon trap to restart execution at the previous
1276       // CmpI. Check that this change in a previous compilation didn't
1277       // cause too many traps.
1278       int trap_request = unc->uncommon_trap_request();
1279       Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(trap_request);
1280 
1281       if (igvn->C->too_many_traps(dom_unc->jvms()->method(), dom_unc->jvms()->bci(), reason)) {
1282         return false;
1283       }
1284 
1285       if (!is_dominator_unc(dom_unc, unc)) {
1286         return false;
1287       }
1288 
1289       return true;
1290     }
1291   }
1292   return false;
1293 }
1294 
1295 // Make the If between the 2 integer comparisons trap at the state of
1296 // the first If: the last CmpI is the one replaced by a CmpU and the
1297 // first CmpI is eliminated, so the test between the 2 CmpI nodes
1298 // won't be guarded by the first CmpI anymore. It can trap in cases
1299 // where the first CmpI would have prevented it from executing: on a
1300 // trap, we need to restart execution at the state of the first CmpI
1301 void IfNode::reroute_side_effect_free_unc(ProjNode* proj, ProjNode* dom_proj, PhaseIterGVN* igvn) {
1302   CallStaticJavaNode* dom_unc = dom_proj->is_uncommon_trap_if_pattern();
1303   ProjNode* otherproj = proj->other_if_proj();
1304   CallStaticJavaNode* unc = proj->is_uncommon_trap_if_pattern();
1305   Node* call_proj = dom_unc->unique_ctrl_out();
1306   Node* halt = call_proj->unique_ctrl_out();
1307 
1308   Node* new_unc = dom_unc->clone();
1309   call_proj = call_proj->clone();
1310   halt = halt->clone();
1311   Node* c = otherproj->clone();
1312 
1313   c = igvn->transform(c);
1314   new_unc->set_req(TypeFunc::Parms, unc->in(TypeFunc::Parms));
1315   new_unc->set_req(0, c);
1316   new_unc = igvn->transform(new_unc);
1317   call_proj->set_req(0, new_unc);
1318   call_proj = igvn->transform(call_proj);
1319   halt->set_req(0, call_proj);
1320   halt = igvn->transform(halt);
1321 
1322   igvn->replace_node(otherproj, igvn->C->top());
1323   igvn->C->root()->add_req(halt);
1324 }
1325 
1326 Node* IfNode::fold_compares(PhaseIterGVN* igvn) {
1327   if (Opcode() != Op_If) return nullptr;
1328 
1329   if (cmpi_folds(igvn)) {
1330     Node* ctrl = in(0);
1331     if (is_ctrl_folds(ctrl, igvn) && ctrl->outcnt() == 1) {
1332       // A integer comparison immediately dominated by another integer
1333       // comparison
1334       ProjNode* success = nullptr;
1335       ProjNode* fail = nullptr;
1336       ProjNode* dom_cmp = ctrl->as_Proj();
1337       if (has_shared_region(dom_cmp, success, fail) &&
1338           // Next call modifies graph so must be last
1339           fold_compares_helper(dom_cmp, success, fail, igvn)) {
1340         return this;
1341       }
1342       if (has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1343           // Next call modifies graph so must be last
1344           fold_compares_helper(dom_cmp, success, fail, igvn)) {
1345         return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1346       }
1347       return nullptr;
1348     } else if (ctrl->in(0) != nullptr &&
1349                ctrl->in(0)->in(0) != nullptr) {
1350       ProjNode* success = nullptr;
1351       ProjNode* fail = nullptr;
1352       Node* dom = ctrl->in(0)->in(0);
1353       ProjNode* dom_cmp = dom->isa_Proj();
1354       ProjNode* other_cmp = ctrl->isa_Proj();
1355 
1356       // Check if it's an integer comparison dominated by another
1357       // integer comparison with another test in between
1358       if (is_ctrl_folds(dom, igvn) &&
1359           has_only_uncommon_traps(dom_cmp, success, fail, igvn) &&
1360           is_side_effect_free_test(other_cmp, igvn) &&
1361           // Next call modifies graph so must be last
1362           fold_compares_helper(dom_cmp, success, fail, igvn)) {
1363         reroute_side_effect_free_unc(other_cmp, dom_cmp, igvn);
1364         return merge_uncommon_traps(dom_cmp, success, fail, igvn);
1365       }
1366     }
1367   }
1368   return nullptr;
1369 }
1370 
1371 //------------------------------remove_useless_bool----------------------------
1372 // Check for people making a useless boolean: things like
1373 // if( (x < y ? true : false) ) { ... }
1374 // Replace with if( x < y ) { ... }
1375 static Node *remove_useless_bool(IfNode *iff, PhaseGVN *phase) {
1376   Node *i1 = iff->in(1);
1377   if( !i1->is_Bool() ) return nullptr;
1378   BoolNode *bol = i1->as_Bool();
1379 
1380   Node *cmp = bol->in(1);
1381   if( cmp->Opcode() != Op_CmpI ) return nullptr;
1382 
1383   // Must be comparing against a bool
1384   const Type *cmp2_t = phase->type( cmp->in(2) );
1385   if( cmp2_t != TypeInt::ZERO &&
1386       cmp2_t != TypeInt::ONE )
1387     return nullptr;
1388 
1389   // Find a prior merge point merging the boolean
1390   i1 = cmp->in(1);
1391   if( !i1->is_Phi() ) return nullptr;
1392   PhiNode *phi = i1->as_Phi();
1393   if( phase->type( phi ) != TypeInt::BOOL )
1394     return nullptr;
1395 
1396   // Check for diamond pattern
1397   int true_path = phi->is_diamond_phi();
1398   if( true_path == 0 ) return nullptr;
1399 
1400   // Make sure that iff and the control of the phi are different. This
1401   // should really only happen for dead control flow since it requires
1402   // an illegal cycle.
1403   if (phi->in(0)->in(1)->in(0) == iff) return nullptr;
1404 
1405   // phi->region->if_proj->ifnode->bool->cmp
1406   BoolNode *bol2 = phi->in(0)->in(1)->in(0)->in(1)->as_Bool();
1407 
1408   // Now get the 'sense' of the test correct so we can plug in
1409   // either iff2->in(1) or its complement.
1410   int flip = 0;
1411   if( bol->_test._test == BoolTest::ne ) flip = 1-flip;
1412   else if( bol->_test._test != BoolTest::eq ) return nullptr;
1413   if( cmp2_t == TypeInt::ZERO ) flip = 1-flip;
1414 
1415   const Type *phi1_t = phase->type( phi->in(1) );
1416   const Type *phi2_t = phase->type( phi->in(2) );
1417   // Check for Phi(0,1) and flip
1418   if( phi1_t == TypeInt::ZERO ) {
1419     if( phi2_t != TypeInt::ONE ) return nullptr;
1420     flip = 1-flip;
1421   } else {
1422     // Check for Phi(1,0)
1423     if( phi1_t != TypeInt::ONE  ) return nullptr;
1424     if( phi2_t != TypeInt::ZERO ) return nullptr;
1425   }
1426   if( true_path == 2 ) {
1427     flip = 1-flip;
1428   }
1429 
1430   Node* new_bol = (flip ? phase->transform( bol2->negate(phase) ) : bol2);
1431   assert(new_bol != iff->in(1), "must make progress");
1432   iff->set_req_X(1, new_bol, phase);
1433   // Intervening diamond probably goes dead
1434   phase->C->set_major_progress();
1435   return iff;
1436 }
1437 
1438 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff);
1439 
1440 struct RangeCheck {
1441   IfProjNode* ctl;
1442   jint off;
1443 };
1444 
1445 Node* IfNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
1446   if (remove_dead_region(phase, can_reshape))  return this;
1447   // No Def-Use info?
1448   if (!can_reshape)  return nullptr;
1449 
1450   // Don't bother trying to transform a dead if
1451   if (in(0)->is_top())  return nullptr;
1452   // Don't bother trying to transform an if with a dead test
1453   if (in(1)->is_top())  return nullptr;
1454   // Another variation of a dead test
1455   if (in(1)->is_Con())  return nullptr;
1456   // Another variation of a dead if
1457   if (outcnt() < 2)  return nullptr;
1458 
1459   // Canonicalize the test.
1460   Node* idt_if = idealize_test(phase, this);
1461   if (idt_if != nullptr)  return idt_if;
1462 
1463   // Try to split the IF
1464   PhaseIterGVN *igvn = phase->is_IterGVN();
1465   Node *s = split_if(this, igvn);
1466   if (s != nullptr)  return s;
1467 
1468   return NodeSentinel;
1469 }
1470 
1471 //------------------------------Ideal------------------------------------------
1472 // Return a node which is more "ideal" than the current node.  Strip out
1473 // control copies
1474 Node* IfNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1475   Node* res = Ideal_common(phase, can_reshape);
1476   if (res != NodeSentinel) {
1477     return res;
1478   }
1479 
1480   // Check for people making a useless boolean: things like
1481   // if( (x < y ? true : false) ) { ... }
1482   // Replace with if( x < y ) { ... }
1483   Node* bol2 = remove_useless_bool(this, phase);
1484   if (bol2) return bol2;
1485 
1486   if (in(0) == nullptr) return nullptr;     // Dead loop?
1487 
1488   PhaseIterGVN* igvn = phase->is_IterGVN();
1489   Node* result = fold_compares(igvn);
1490   if (result != nullptr) {
1491     return result;
1492   }
1493 
1494   // Scan for an equivalent test
1495   int dist = 4;               // Cutoff limit for search
1496   if (is_If() && in(1)->is_Bool()) {
1497     Node* cmp = in(1)->in(1);
1498     if (cmp->Opcode() == Op_CmpP &&
1499         cmp->in(2) != nullptr && // make sure cmp is not already dead
1500         cmp->in(2)->bottom_type() == TypePtr::NULL_PTR) {
1501       dist = 64;              // Limit for null-pointer scans
1502     }
1503   }
1504 
1505   Node* prev_dom = search_identical(dist, igvn);
1506 
1507   if (prev_dom != nullptr) {
1508     // Replace dominated IfNode
1509     return dominated_by(prev_dom, igvn, false);
1510   }
1511 
1512   return simple_subsuming(igvn);
1513 }
1514 
1515 //------------------------------dominated_by-----------------------------------
1516 Node* IfNode::dominated_by(Node* prev_dom, PhaseIterGVN* igvn, bool pin_array_access_nodes) {
1517 #ifndef PRODUCT
1518   if (TraceIterativeGVN) {
1519     tty->print("   Removing IfNode: "); this->dump();
1520   }
1521 #endif
1522 
1523   igvn->hash_delete(this);      // Remove self to prevent spurious V-N
1524   Node *idom = in(0);
1525   // Need opcode to decide which way 'this' test goes
1526   int prev_op = prev_dom->Opcode();
1527   Node *top = igvn->C->top(); // Shortcut to top
1528 
1529   // Now walk the current IfNode's projections.
1530   // Loop ends when 'this' has no more uses.
1531   for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
1532     Node *ifp = last_out(i);     // Get IfTrue/IfFalse
1533     igvn->add_users_to_worklist(ifp);
1534     // Check which projection it is and set target.
1535     // Data-target is either the dominating projection of the same type
1536     // or TOP if the dominating projection is of opposite type.
1537     // Data-target will be used as the new control edge for the non-CFG
1538     // nodes like Casts and Loads.
1539     Node *data_target = (ifp->Opcode() == prev_op) ? prev_dom : top;
1540     // Control-target is just the If's immediate dominator or TOP.
1541     Node *ctrl_target = (ifp->Opcode() == prev_op) ?     idom : top;
1542 
1543     // For each child of an IfTrue/IfFalse projection, reroute.
1544     // Loop ends when projection has no more uses.
1545     for (DUIterator_Last jmin, j = ifp->last_outs(jmin); j >= jmin; --j) {
1546       Node* s = ifp->last_out(j);   // Get child of IfTrue/IfFalse
1547       if (s->depends_only_on_test() && igvn->no_dependent_zero_check(s)) {
1548         // For control producers.
1549         // Do not rewire Div and Mod nodes which could have a zero divisor to avoid skipping their zero check.
1550         igvn->replace_input_of(s, 0, data_target); // Move child to data-target
1551         if (pin_array_access_nodes && data_target != top) {
1552           // As a result of range check smearing, Loads and range check Cast nodes that are control dependent on this
1553           // range check (that is about to be removed) now depend on multiple dominating range checks. After the removal
1554           // of this range check, these control dependent nodes end up at the lowest/nearest dominating check in the
1555           // graph. To ensure that these Loads/Casts do not float above any of the dominating checks (even when the
1556           // lowest dominating check is later replaced by yet another dominating check), we need to pin them at the
1557           // lowest dominating check.
1558           Node* clone = s->pin_array_access_node();
1559           if (clone != nullptr) {
1560             clone = igvn->transform(clone);
1561             igvn->replace_node(s, clone);
1562           }
1563         }
1564       } else {
1565         // Find the control input matching this def-use edge.
1566         // For Regions it may not be in slot 0.
1567         uint l;
1568         for (l = 0; s->in(l) != ifp; l++) { }
1569         igvn->replace_input_of(s, l, ctrl_target);
1570       }
1571     } // End for each child of a projection
1572 
1573     igvn->remove_dead_node(ifp);
1574   } // End for each IfTrue/IfFalse child of If
1575 
1576   // Kill the IfNode
1577   igvn->remove_dead_node(this);
1578 
1579   // Must return either the original node (now dead) or a new node
1580   // (Do not return a top here, since that would break the uniqueness of top.)
1581   return new ConINode(TypeInt::ZERO);
1582 }
1583 
1584 Node* IfNode::search_identical(int dist, PhaseIterGVN* igvn) {
1585   // Setup to scan up the CFG looking for a dominating test
1586   Node* dom = in(0);
1587   Node* prev_dom = this;
1588   int op = Opcode();
1589   // Search up the dominator tree for an If with an identical test
1590   while (dom->Opcode() != op ||  // Not same opcode?
1591          !same_condition(dom, igvn) ||  // Not same input 1?
1592          prev_dom->in(0) != dom) {  // One path of test does not dominate?
1593     if (dist < 0) return nullptr;
1594 
1595     dist--;
1596     prev_dom = dom;
1597     dom = up_one_dom(dom);
1598     if (!dom) return nullptr;
1599   }
1600 
1601   // Check that we did not follow a loop back to ourselves
1602   if (this == dom) {
1603     return nullptr;
1604   }
1605 
1606 #ifndef PRODUCT
1607   if (dist > 2) { // Add to count of null checks elided
1608     explicit_null_checks_elided++;
1609   }
1610 #endif
1611 
1612   return prev_dom;
1613 }
1614 
1615 bool IfNode::same_condition(const Node* dom, PhaseIterGVN* igvn) const {
1616   Node* dom_bool = dom->in(1);
1617   Node* this_bool = in(1);
1618   if (dom_bool == this_bool) {
1619     return true;
1620   }
1621 
1622   if (dom_bool == nullptr || !dom_bool->is_Bool() ||
1623       this_bool == nullptr || !this_bool->is_Bool()) {
1624     return false;
1625   }
1626   Node* dom_cmp = dom_bool->in(1);
1627   Node* this_cmp = this_bool->in(1);
1628 
1629   // If the comparison is a subtype check, then SubTypeCheck nodes may have profile data attached to them and may be
1630   // different nodes even-though they perform the same subtype check
1631   if (dom_cmp == nullptr || !dom_cmp->is_SubTypeCheck() ||
1632       this_cmp == nullptr || !this_cmp->is_SubTypeCheck()) {
1633     return false;
1634   }
1635 
1636   if (dom_cmp->in(1) != this_cmp->in(1) ||
1637       dom_cmp->in(2) != this_cmp->in(2) ||
1638       dom_bool->as_Bool()->_test._test != this_bool->as_Bool()->_test._test) {
1639     return false;
1640   }
1641 
1642   return true;
1643 }
1644 
1645 
1646 static int subsuming_bool_test_encode(Node*);
1647 
1648 // Check if dominating test is subsuming 'this' one.
1649 //
1650 //              cmp
1651 //              / \
1652 //     (r1)  bool  \
1653 //            /    bool (r2)
1654 //    (dom) if       \
1655 //            \       )
1656 //    (pre)  if[TF]  /
1657 //               \  /
1658 //                if (this)
1659 //   \r1
1660 //  r2\  eqT  eqF  neT  neF  ltT  ltF  leT  leF  gtT  gtF  geT  geF
1661 //  eq    t    f    f    t    f    -    -    f    f    -    -    f
1662 //  ne    f    t    t    f    t    -    -    t    t    -    -    t
1663 //  lt    f    -    -    f    t    f    -    f    f    -    f    t
1664 //  le    t    -    -    t    t    -    t    f    f    t    -    t
1665 //  gt    f    -    -    f    f    -    f    t    t    f    -    f
1666 //  ge    t    -    -    t    f    t    -    t    t    -    t    f
1667 //
1668 Node* IfNode::simple_subsuming(PhaseIterGVN* igvn) {
1669   // Table encoding: N/A (na), True-branch (tb), False-branch (fb).
1670   static enum { na, tb, fb } s_short_circuit_map[6][12] = {
1671   /*rel: eq+T eq+F ne+T ne+F lt+T lt+F le+T le+F gt+T gt+F ge+T ge+F*/
1672   /*eq*/{ tb,  fb,  fb,  tb,  fb,  na,  na,  fb,  fb,  na,  na,  fb },
1673   /*ne*/{ fb,  tb,  tb,  fb,  tb,  na,  na,  tb,  tb,  na,  na,  tb },
1674   /*lt*/{ fb,  na,  na,  fb,  tb,  fb,  na,  fb,  fb,  na,  fb,  tb },
1675   /*le*/{ tb,  na,  na,  tb,  tb,  na,  tb,  fb,  fb,  tb,  na,  tb },
1676   /*gt*/{ fb,  na,  na,  fb,  fb,  na,  fb,  tb,  tb,  fb,  na,  fb },
1677   /*ge*/{ tb,  na,  na,  tb,  fb,  tb,  na,  tb,  tb,  na,  tb,  fb }};
1678 
1679   Node* pre = in(0);
1680   if (!pre->is_IfTrue() && !pre->is_IfFalse()) {
1681     return nullptr;
1682   }
1683   Node* dom = pre->in(0);
1684   if (!dom->is_If()) {
1685     return nullptr;
1686   }
1687   Node* bol = in(1);
1688   if (!bol->is_Bool()) {
1689     return nullptr;
1690   }
1691   Node* cmp = in(1)->in(1);
1692   if (!cmp->is_Cmp()) {
1693     return nullptr;
1694   }
1695 
1696   if (!dom->in(1)->is_Bool()) {
1697     return nullptr;
1698   }
1699   if (dom->in(1)->in(1) != cmp) {  // Not same cond?
1700     return nullptr;
1701   }
1702 
1703   int drel = subsuming_bool_test_encode(dom->in(1));
1704   int trel = subsuming_bool_test_encode(bol);
1705   int bout = pre->is_IfFalse() ? 1 : 0;
1706 
1707   if (drel < 0 || trel < 0) {
1708     return nullptr;
1709   }
1710   int br = s_short_circuit_map[trel][2*drel+bout];
1711   if (br == na) {
1712     return nullptr;
1713   }
1714 #ifndef PRODUCT
1715   if (TraceIterativeGVN) {
1716     tty->print("   Subsumed IfNode: "); dump();
1717   }
1718 #endif
1719   // Replace condition with constant True(1)/False(0).
1720   bool is_always_true = br == tb;
1721   set_req(1, igvn->intcon(is_always_true ? 1 : 0));
1722 
1723   // Update any data dependencies to the directly dominating test. This subsumed test is not immediately removed by igvn
1724   // and therefore subsequent optimizations might miss these data dependencies otherwise. There might be a dead loop
1725   // ('always_taken_proj' == 'pre') that is cleaned up later. Skip this case to make the iterator work properly.
1726   Node* always_taken_proj = proj_out(is_always_true);
1727   if (always_taken_proj != pre) {
1728     for (DUIterator_Fast imax, i = always_taken_proj->fast_outs(imax); i < imax; i++) {
1729       Node* u = always_taken_proj->fast_out(i);
1730       if (!u->is_CFG()) {
1731         igvn->replace_input_of(u, 0, pre);
1732         --i;
1733         --imax;
1734       }
1735     }
1736   }
1737 
1738   if (bol->outcnt() == 0) {
1739     igvn->remove_dead_node(bol);    // Kill the BoolNode.
1740   }
1741   return this;
1742 }
1743 
1744 // Map BoolTest to local table encoding. The BoolTest (e)numerals
1745 //   { eq = 0, ne = 4, le = 5, ge = 7, lt = 3, gt = 1 }
1746 // are mapped to table indices, while the remaining (e)numerals in BoolTest
1747 //   { overflow = 2, no_overflow = 6, never = 8, illegal = 9 }
1748 // are ignored (these are not modeled in the table).
1749 //
1750 static int subsuming_bool_test_encode(Node* node) {
1751   precond(node->is_Bool());
1752   BoolTest::mask x = node->as_Bool()->_test._test;
1753   switch (x) {
1754     case BoolTest::eq: return 0;
1755     case BoolTest::ne: return 1;
1756     case BoolTest::lt: return 2;
1757     case BoolTest::le: return 3;
1758     case BoolTest::gt: return 4;
1759     case BoolTest::ge: return 5;
1760     case BoolTest::overflow:
1761     case BoolTest::no_overflow:
1762     case BoolTest::never:
1763     case BoolTest::illegal:
1764     default:
1765       return -1;
1766   }
1767 }
1768 
1769 //------------------------------Identity---------------------------------------
1770 // If the test is constant & we match, then we are the input Control
1771 Node* IfProjNode::Identity(PhaseGVN* phase) {
1772   // Can only optimize if cannot go the other way
1773   const TypeTuple *t = phase->type(in(0))->is_tuple();
1774   if (t == TypeTuple::IFNEITHER || (always_taken(t) &&
1775        // During parsing (GVN) we don't remove dead code aggressively.
1776        // Cut off dead branch and let PhaseRemoveUseless take care of it.
1777       (!phase->is_IterGVN() ||
1778        // During IGVN, first wait for the dead branch to be killed.
1779        // Otherwise, the IfNode's control will have two control uses (the IfNode
1780        // that doesn't go away because it still has uses and this branch of the
1781        // If) which breaks other optimizations. Node::has_special_unique_user()
1782        // will cause this node to be reprocessed once the dead branch is killed.
1783        in(0)->outcnt() == 1))) {
1784     // IfNode control
1785     if (in(0)->is_BaseCountedLoopEnd()) {
1786       // CountedLoopEndNode may be eliminated by if subsuming, replace CountedLoopNode with LoopNode to
1787       // avoid mismatching between CountedLoopNode and CountedLoopEndNode in the following optimization.
1788       Node* head = unique_ctrl_out_or_null();
1789       if (head != nullptr && head->is_BaseCountedLoop() && head->in(LoopNode::LoopBackControl) == this) {
1790         Node* new_head = new LoopNode(head->in(LoopNode::EntryControl), this);
1791         phase->is_IterGVN()->register_new_node_with_optimizer(new_head);
1792         phase->is_IterGVN()->replace_node(head, new_head);
1793       }
1794     }
1795     return in(0)->in(0);
1796   }
1797   // no progress
1798   return this;
1799 }
1800 
1801 bool IfNode::is_zero_trip_guard() const {
1802   if (in(1)->is_Bool() && in(1)->in(1)->is_Cmp()) {
1803     return in(1)->in(1)->in(1)->Opcode() == Op_OpaqueZeroTripGuard;
1804   }
1805   return false;
1806 }
1807 
1808 void IfProjNode::pin_array_access_nodes(PhaseIterGVN* igvn) {
1809   for (DUIterator i = outs(); has_out(i); i++) {
1810     Node* u = out(i);
1811     if (!u->depends_only_on_test()) {
1812       continue;
1813     }
1814     Node* clone = u->pin_array_access_node();
1815     if (clone != nullptr) {
1816       clone = igvn->transform(clone);
1817       assert(clone != u, "shouldn't common");
1818       igvn->replace_node(u, clone);
1819       --i;
1820     }
1821   }
1822 }
1823 
1824 #ifndef PRODUCT
1825 //------------------------------dump_spec--------------------------------------
1826 void IfNode::dump_spec(outputStream *st) const {
1827   st->print("P=%f, C=%f",_prob,_fcnt);
1828 }
1829 #endif
1830 
1831 //------------------------------idealize_test----------------------------------
1832 // Try to canonicalize tests better.  Peek at the Cmp/Bool/If sequence and
1833 // come up with a canonical sequence.  Bools getting 'eq', 'gt' and 'ge' forms
1834 // converted to 'ne', 'le' and 'lt' forms.  IfTrue/IfFalse get swapped as
1835 // needed.
1836 static IfNode* idealize_test(PhaseGVN* phase, IfNode* iff) {
1837   assert(iff->in(0) != nullptr, "If must be live");
1838 
1839   if (iff->outcnt() != 2)  return nullptr; // Malformed projections.
1840   Node* old_if_f = iff->proj_out(false);
1841   Node* old_if_t = iff->proj_out(true);
1842 
1843   // CountedLoopEnds want the back-control test to be TRUE, regardless of
1844   // whether they are testing a 'gt' or 'lt' condition.  The 'gt' condition
1845   // happens in count-down loops
1846   if (iff->is_BaseCountedLoopEnd())  return nullptr;
1847   if (!iff->in(1)->is_Bool())  return nullptr; // Happens for partially optimized IF tests
1848   BoolNode *b = iff->in(1)->as_Bool();
1849   BoolTest bt = b->_test;
1850   // Test already in good order?
1851   if( bt.is_canonical() )
1852     return nullptr;
1853 
1854   // Flip test to be canonical.  Requires flipping the IfFalse/IfTrue and
1855   // cloning the IfNode.
1856   Node* new_b = phase->transform( new BoolNode(b->in(1), bt.negate()) );
1857   if( !new_b->is_Bool() ) return nullptr;
1858   b = new_b->as_Bool();
1859 
1860   PhaseIterGVN *igvn = phase->is_IterGVN();
1861   assert( igvn, "Test is not canonical in parser?" );
1862 
1863   // The IF node never really changes, but it needs to be cloned
1864   iff = iff->clone()->as_If();
1865   iff->set_req(1, b);
1866   iff->_prob = 1.0-iff->_prob;
1867 
1868   Node *prior = igvn->hash_find_insert(iff);
1869   if( prior ) {
1870     igvn->remove_dead_node(iff);
1871     iff = (IfNode*)prior;
1872   } else {
1873     // Cannot call transform on it just yet
1874     igvn->set_type_bottom(iff);
1875   }
1876   igvn->_worklist.push(iff);
1877 
1878   // Now handle projections.  Cloning not required.
1879   Node* new_if_f = (Node*)(new IfFalseNode( iff ));
1880   Node* new_if_t = (Node*)(new IfTrueNode ( iff ));
1881 
1882   igvn->register_new_node_with_optimizer(new_if_f);
1883   igvn->register_new_node_with_optimizer(new_if_t);
1884   // Flip test, so flip trailing control
1885   igvn->replace_node(old_if_f, new_if_t);
1886   igvn->replace_node(old_if_t, new_if_f);
1887 
1888   // Progress
1889   return iff;
1890 }
1891 
1892 Node* RangeCheckNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1893   Node* res = Ideal_common(phase, can_reshape);
1894   if (res != NodeSentinel) {
1895     return res;
1896   }
1897 
1898   PhaseIterGVN *igvn = phase->is_IterGVN();
1899   // Setup to scan up the CFG looking for a dominating test
1900   Node* prev_dom = this;
1901 
1902   // Check for range-check vs other kinds of tests
1903   Node* index1;
1904   Node* range1;
1905   jint offset1;
1906   int flip1 = is_range_check(range1, index1, offset1);
1907   if (flip1) {
1908     Node* dom = in(0);
1909     // Try to remove extra range checks.  All 'up_one_dom' gives up at merges
1910     // so all checks we inspect post-dominate the top-most check we find.
1911     // If we are going to fail the current check and we reach the top check
1912     // then we are guaranteed to fail, so just start interpreting there.
1913     // We 'expand' the top 3 range checks to include all post-dominating
1914     // checks.
1915     //
1916     // Example:
1917     // a[i+x] // (1) 1 < x < 6
1918     // a[i+3] // (2)
1919     // a[i+4] // (3)
1920     // a[i+6] // max = max of all constants
1921     // a[i+2]
1922     // a[i+1] // min = min of all constants
1923     //
1924     // If x < 3:
1925     //   (1) a[i+x]: Leave unchanged
1926     //   (2) a[i+3]: Replace with a[i+max] = a[i+6]: i+x < i+3 <= i+6  -> (2) is covered
1927     //   (3) a[i+4]: Replace with a[i+min] = a[i+1]: i+1 < i+4 <= i+6  -> (3) and all following checks are covered
1928     //   Remove all other a[i+c] checks
1929     //
1930     // If x >= 3:
1931     //   (1) a[i+x]: Leave unchanged
1932     //   (2) a[i+3]: Replace with a[i+min] = a[i+1]: i+1 < i+3 <= i+x  -> (2) is covered
1933     //   (3) a[i+4]: Replace with a[i+max] = a[i+6]: i+1 < i+4 <= i+6  -> (3) and all following checks are covered
1934     //   Remove all other a[i+c] checks
1935     //
1936     // We only need the top 2 range checks if x is the min or max of all constants.
1937     //
1938     // This, however, only works if the interval [i+min,i+max] is not larger than max_int (i.e. abs(max - min) < max_int):
1939     // The theoretical max size of an array is max_int with:
1940     // - Valid index space: [0,max_int-1]
1941     // - Invalid index space: [max_int,-1] // max_int, min_int, min_int - 1 ..., -1
1942     //
1943     // The size of the consecutive valid index space is smaller than the size of the consecutive invalid index space.
1944     // If we choose min and max in such a way that:
1945     // - abs(max - min) < max_int
1946     // - i+max and i+min are inside the valid index space
1947     // then all indices [i+min,i+max] must be in the valid index space. Otherwise, the invalid index space must be
1948     // smaller than the valid index space which is never the case for any array size.
1949     //
1950     // Choosing a smaller array size only makes the valid index space smaller and the invalid index space larger and
1951     // the argument above still holds.
1952     //
1953     // Note that the same optimization with the same maximal accepted interval size can also be found in C1.
1954     const jlong maximum_number_of_min_max_interval_indices = (jlong)max_jint;
1955 
1956     // The top 3 range checks seen
1957     const int NRC = 3;
1958     RangeCheck prev_checks[NRC];
1959     int nb_checks = 0;
1960 
1961     // Low and high offsets seen so far
1962     jint off_lo = offset1;
1963     jint off_hi = offset1;
1964 
1965     bool found_immediate_dominator = false;
1966 
1967     // Scan for the top checks and collect range of offsets
1968     for (int dist = 0; dist < 999; dist++) { // Range-Check scan limit
1969       if (dom->Opcode() == Op_RangeCheck &&  // Not same opcode?
1970           prev_dom->in(0) == dom) { // One path of test does dominate?
1971         if (dom == this) return nullptr; // dead loop
1972         // See if this is a range check
1973         Node* index2;
1974         Node* range2;
1975         jint offset2;
1976         int flip2 = dom->as_RangeCheck()->is_range_check(range2, index2, offset2);
1977         // See if this is a _matching_ range check, checking against
1978         // the same array bounds.
1979         if (flip2 == flip1 && range2 == range1 && index2 == index1 &&
1980             dom->outcnt() == 2) {
1981           if (nb_checks == 0 && dom->in(1) == in(1)) {
1982             // Found an immediately dominating test at the same offset.
1983             // This kind of back-to-back test can be eliminated locally,
1984             // and there is no need to search further for dominating tests.
1985             assert(offset2 == offset1, "Same test but different offsets");
1986             found_immediate_dominator = true;
1987             break;
1988           }
1989 
1990           // "x - y" -> must add one to the difference for number of elements in [x,y]
1991           const jlong diff = (jlong)MIN2(offset2, off_lo) - (jlong)MAX2(offset2, off_hi);
1992           if (ABS(diff) < maximum_number_of_min_max_interval_indices) {
1993             // Gather expanded bounds
1994             off_lo = MIN2(off_lo, offset2);
1995             off_hi = MAX2(off_hi, offset2);
1996             // Record top NRC range checks
1997             prev_checks[nb_checks % NRC].ctl = prev_dom->as_IfProj();
1998             prev_checks[nb_checks % NRC].off = offset2;
1999             nb_checks++;
2000           }
2001         }
2002       }
2003       prev_dom = dom;
2004       dom = up_one_dom(dom);
2005       if (!dom) break;
2006     }
2007 
2008     if (!found_immediate_dominator) {
2009       // Attempt to widen the dominating range check to cover some later
2010       // ones.  Since range checks "fail" by uncommon-trapping to the
2011       // interpreter, widening a check can make us speculatively enter
2012       // the interpreter.  If we see range-check deopt's, do not widen!
2013       if (!phase->C->allow_range_check_smearing())  return nullptr;
2014 
2015       if (can_reshape && !phase->C->post_loop_opts_phase()) {
2016         // We are about to perform range check smearing (i.e. remove this RangeCheck if it is dominated by
2017         // a series of RangeChecks which have a range that covers this RangeCheck). This can cause array access nodes to
2018         // be pinned. We want to avoid that and first allow range check elimination a chance to remove the RangeChecks
2019         // from loops. Hence, we delay range check smearing until after loop opts.
2020         phase->C->record_for_post_loop_opts_igvn(this);
2021         return nullptr;
2022       }
2023 
2024       // Didn't find prior covering check, so cannot remove anything.
2025       if (nb_checks == 0) {
2026         return nullptr;
2027       }
2028       // Constant indices only need to check the upper bound.
2029       // Non-constant indices must check both low and high.
2030       int chk0 = (nb_checks - 1) % NRC;
2031       if (index1) {
2032         if (nb_checks == 1) {
2033           return nullptr;
2034         } else {
2035           // If the top range check's constant is the min or max of
2036           // all constants we widen the next one to cover the whole
2037           // range of constants.
2038           RangeCheck rc0 = prev_checks[chk0];
2039           int chk1 = (nb_checks - 2) % NRC;
2040           RangeCheck rc1 = prev_checks[chk1];
2041           if (rc0.off == off_lo) {
2042             adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
2043             prev_dom = rc1.ctl;
2044           } else if (rc0.off == off_hi) {
2045             adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
2046             prev_dom = rc1.ctl;
2047           } else {
2048             // If the top test's constant is not the min or max of all
2049             // constants, we need 3 range checks. We must leave the
2050             // top test unchanged because widening it would allow the
2051             // accesses it protects to successfully read/write out of
2052             // bounds.
2053             if (nb_checks == 2) {
2054               return nullptr;
2055             }
2056             int chk2 = (nb_checks - 3) % NRC;
2057             RangeCheck rc2 = prev_checks[chk2];
2058             // The top range check a+i covers interval: -a <= i < length-a
2059             // The second range check b+i covers interval: -b <= i < length-b
2060             if (rc1.off <= rc0.off) {
2061               // if b <= a, we change the second range check to:
2062               // -min_of_all_constants <= i < length-min_of_all_constants
2063               // Together top and second range checks now cover:
2064               // -min_of_all_constants <= i < length-a
2065               // which is more restrictive than -b <= i < length-b:
2066               // -b <= -min_of_all_constants <= i < length-a <= length-b
2067               // The third check is then changed to:
2068               // -max_of_all_constants <= i < length-max_of_all_constants
2069               // so 2nd and 3rd checks restrict allowed values of i to:
2070               // -min_of_all_constants <= i < length-max_of_all_constants
2071               adjust_check(rc1.ctl, range1, index1, flip1, off_lo, igvn);
2072               adjust_check(rc2.ctl, range1, index1, flip1, off_hi, igvn);
2073             } else {
2074               // if b > a, we change the second range check to:
2075               // -max_of_all_constants <= i < length-max_of_all_constants
2076               // Together top and second range checks now cover:
2077               // -a <= i < length-max_of_all_constants
2078               // which is more restrictive than -b <= i < length-b:
2079               // -b < -a <= i < length-max_of_all_constants <= length-b
2080               // The third check is then changed to:
2081               // -max_of_all_constants <= i < length-max_of_all_constants
2082               // so 2nd and 3rd checks restrict allowed values of i to:
2083               // -min_of_all_constants <= i < length-max_of_all_constants
2084               adjust_check(rc1.ctl, range1, index1, flip1, off_hi, igvn);
2085               adjust_check(rc2.ctl, range1, index1, flip1, off_lo, igvn);
2086             }
2087             prev_dom = rc2.ctl;
2088           }
2089         }
2090       } else {
2091         RangeCheck rc0 = prev_checks[chk0];
2092         // 'Widen' the offset of the 1st and only covering check
2093         adjust_check(rc0.ctl, range1, index1, flip1, off_hi, igvn);
2094         // Test is now covered by prior checks, dominate it out
2095         prev_dom = rc0.ctl;
2096       }
2097       // The last RangeCheck is found to be redundant with a sequence of n (n >= 2) preceding RangeChecks.
2098       // If an array load is control dependent on the eliminated range check, the array load nodes (CastII and Load)
2099       // become control dependent on the last range check of the sequence, but they are really dependent on the entire
2100       // sequence of RangeChecks. If RangeCheck#n is later replaced by a dominating identical check, the array load
2101       // nodes must not float above the n-1 other RangeCheck in the sequence. We pin the array load nodes here to
2102       // guarantee it doesn't happen.
2103       //
2104       // RangeCheck#1                 RangeCheck#1
2105       //    |      \                     |      \
2106       //    |      uncommon trap         |      uncommon trap
2107       //    ..                           ..
2108       // RangeCheck#n              -> RangeCheck#n
2109       //    |      \                     |      \
2110       //    |      uncommon trap        CastII  uncommon trap
2111       // RangeCheck                     Load
2112       //    |      \
2113       //   CastII  uncommon trap
2114       //   Load
2115 
2116       return dominated_by(prev_dom, igvn, true);
2117     }
2118   } else {
2119     prev_dom = search_identical(4, igvn);
2120 
2121     if (prev_dom == nullptr) {
2122       return nullptr;
2123     }
2124   }
2125 
2126   // Replace dominated IfNode
2127   return dominated_by(prev_dom, igvn, false);
2128 }
2129 
2130 ParsePredicateNode::ParsePredicateNode(Node* control, Deoptimization::DeoptReason deopt_reason, PhaseGVN* gvn)
2131     : IfNode(control, gvn->intcon(1), PROB_MAX, COUNT_UNKNOWN),
2132       _deopt_reason(deopt_reason),
2133       _useless(false) {
2134   init_class_id(Class_ParsePredicate);
2135   gvn->C->add_parse_predicate(this);
2136   gvn->C->record_for_post_loop_opts_igvn(this);
2137 #ifdef ASSERT
2138   switch (deopt_reason) {
2139     case Deoptimization::Reason_predicate:
2140     case Deoptimization::Reason_profile_predicate:
2141     case Deoptimization::Reason_loop_limit_check:
2142       break;
2143     default:
2144       assert(false, "unsupported deoptimization reason for Parse Predicate");
2145   }
2146 #endif // ASSERT
2147 }
2148 
2149 Node* ParsePredicateNode::uncommon_trap() const {
2150   ParsePredicateUncommonProj* uncommon_proj = proj_out(0)->as_IfFalse();
2151   Node* uct_region_or_call = uncommon_proj->unique_ctrl_out();
2152   assert(uct_region_or_call->is_Region() || uct_region_or_call->is_Call(), "must be a region or call uct");
2153   return uct_region_or_call;
2154 }
2155 
2156 // Fold this node away once it becomes useless or at latest in post loop opts IGVN.
2157 const Type* ParsePredicateNode::Value(PhaseGVN* phase) const {
2158   if (phase->type(in(0)) == Type::TOP) {
2159     return Type::TOP;
2160   }
2161   if (_useless || phase->C->post_loop_opts_phase()) {
2162     return TypeTuple::IFTRUE;
2163   } else {
2164     return bottom_type();
2165   }
2166 }
2167 
2168 #ifndef PRODUCT
2169 void ParsePredicateNode::dump_spec(outputStream* st) const {
2170   st->print(" #");
2171   switch (_deopt_reason) {
2172     case Deoptimization::DeoptReason::Reason_predicate:
2173       st->print("Loop ");
2174       break;
2175     case Deoptimization::DeoptReason::Reason_profile_predicate:
2176       st->print("Profiled_Loop ");
2177       break;
2178     case Deoptimization::DeoptReason::Reason_loop_limit_check:
2179       st->print("Loop_Limit_Check ");
2180       break;
2181     default:
2182       fatal("unknown kind");
2183   }
2184 }
2185 
2186 #endif // NOT PRODUCT