1 /*
   2  * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/barrierSet.hpp"
  27 #include "gc/shared/c2/barrierSetC2.hpp"
  28 #include "memory/allocation.inline.hpp"
  29 #include "memory/resourceArea.hpp"
  30 #include "oops/objArrayKlass.hpp"
  31 #include "opto/addnode.hpp"
  32 #include "opto/castnode.hpp"
  33 #include "opto/cfgnode.hpp"
  34 #include "opto/connode.hpp"
  35 #include "opto/convertnode.hpp"
  36 #include "opto/inlinetypenode.hpp"
  37 #include "opto/loopnode.hpp"
  38 #include "opto/machnode.hpp"
  39 #include "opto/movenode.hpp"
  40 #include "opto/narrowptrnode.hpp"
  41 #include "opto/mulnode.hpp"
  42 #include "opto/phaseX.hpp"
  43 #include "opto/regmask.hpp"
  44 #include "opto/runtime.hpp"
  45 #include "opto/subnode.hpp"
  46 #include "opto/vectornode.hpp"
  47 #include "utilities/vmError.hpp"
  48 
  49 // Portions of code courtesy of Clifford Click
  50 
  51 // Optimization - Graph Style
  52 
  53 //=============================================================================
  54 //------------------------------Value------------------------------------------
  55 // Compute the type of the RegionNode.
  56 const Type* RegionNode::Value(PhaseGVN* phase) const {
  57   for( uint i=1; i<req(); ++i ) {       // For all paths in
  58     Node *n = in(i);            // Get Control source
  59     if( !n ) continue;          // Missing inputs are TOP
  60     if( phase->type(n) == Type::CONTROL )
  61       return Type::CONTROL;
  62   }
  63   return Type::TOP;             // All paths dead?  Then so are we
  64 }
  65 
  66 //------------------------------Identity---------------------------------------
  67 // Check for Region being Identity.
  68 Node* RegionNode::Identity(PhaseGVN* phase) {
  69   // Cannot have Region be an identity, even if it has only 1 input.
  70   // Phi users cannot have their Region input folded away for them,
  71   // since they need to select the proper data input
  72   return this;
  73 }
  74 
  75 //------------------------------merge_region-----------------------------------
  76 // If a Region flows into a Region, merge into one big happy merge.  This is
  77 // hard to do if there is stuff that has to happen
  78 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
  79   if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
  80     return NULL;
  81   Node *progress = NULL;        // Progress flag
  82   PhaseIterGVN *igvn = phase->is_IterGVN();
  83 
  84   uint rreq = region->req();
  85   for( uint i = 1; i < rreq; i++ ) {
  86     Node *r = region->in(i);
  87     if( r && r->Opcode() == Op_Region && // Found a region?
  88         r->in(0) == r &&        // Not already collapsed?
  89         r != region &&          // Avoid stupid situations
  90         r->outcnt() == 2 ) {    // Self user and 'region' user only?
  91       assert(!r->as_Region()->has_phi(), "no phi users");
  92       if( !progress ) {         // No progress
  93         if (region->has_phi()) {
  94           return NULL;        // Only flatten if no Phi users
  95           // igvn->hash_delete( phi );
  96         }
  97         igvn->hash_delete( region );
  98         progress = region;      // Making progress
  99       }
 100       igvn->hash_delete( r );
 101 
 102       // Append inputs to 'r' onto 'region'
 103       for( uint j = 1; j < r->req(); j++ ) {
 104         // Move an input from 'r' to 'region'
 105         region->add_req(r->in(j));
 106         r->set_req(j, phase->C->top());
 107         // Update phis of 'region'
 108         //for( uint k = 0; k < max; k++ ) {
 109         //  Node *phi = region->out(k);
 110         //  if( phi->is_Phi() ) {
 111         //    phi->add_req(phi->in(i));
 112         //  }
 113         //}
 114 
 115         rreq++;                 // One more input to Region
 116       } // Found a region to merge into Region
 117       igvn->_worklist.push(r);
 118       // Clobber pointer to the now dead 'r'
 119       region->set_req(i, phase->C->top());
 120     }
 121   }
 122 
 123   return progress;
 124 }
 125 
 126 
 127 
 128 //--------------------------------has_phi--------------------------------------
 129 // Helper function: Return any PhiNode that uses this region or NULL
 130 PhiNode* RegionNode::has_phi() const {
 131   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 132     Node* phi = fast_out(i);
 133     if (phi->is_Phi()) {   // Check for Phi users
 134       assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
 135       return phi->as_Phi();  // this one is good enough
 136     }
 137   }
 138 
 139   return NULL;
 140 }
 141 
 142 
 143 //-----------------------------has_unique_phi----------------------------------
 144 // Helper function: Return the only PhiNode that uses this region or NULL
 145 PhiNode* RegionNode::has_unique_phi() const {
 146   // Check that only one use is a Phi
 147   PhiNode* only_phi = NULL;
 148   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 149     Node* phi = fast_out(i);
 150     if (phi->is_Phi()) {   // Check for Phi users
 151       assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
 152       if (only_phi == NULL) {
 153         only_phi = phi->as_Phi();
 154       } else {
 155         return NULL;  // multiple phis
 156       }
 157     }
 158   }
 159 
 160   return only_phi;
 161 }
 162 
 163 
 164 //------------------------------check_phi_clipping-----------------------------
 165 // Helper function for RegionNode's identification of FP clipping
 166 // Check inputs to the Phi
 167 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
 168   min     = NULL;
 169   max     = NULL;
 170   val     = NULL;
 171   min_idx = 0;
 172   max_idx = 0;
 173   val_idx = 0;
 174   uint  phi_max = phi->req();
 175   if( phi_max == 4 ) {
 176     for( uint j = 1; j < phi_max; ++j ) {
 177       Node *n = phi->in(j);
 178       int opcode = n->Opcode();
 179       switch( opcode ) {
 180       case Op_ConI:
 181         {
 182           if( min == NULL ) {
 183             min     = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
 184             min_idx = j;
 185           } else {
 186             max     = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
 187             max_idx = j;
 188             if( min->get_int() > max->get_int() ) {
 189               // Swap min and max
 190               ConNode *temp;
 191               uint     temp_idx;
 192               temp     = min;     min     = max;     max     = temp;
 193               temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
 194             }
 195           }
 196         }
 197         break;
 198       default:
 199         {
 200           val = n;
 201           val_idx = j;
 202         }
 203         break;
 204       }
 205     }
 206   }
 207   return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
 208 }
 209 
 210 
 211 //------------------------------check_if_clipping------------------------------
 212 // Helper function for RegionNode's identification of FP clipping
 213 // Check that inputs to Region come from two IfNodes,
 214 //
 215 //            If
 216 //      False    True
 217 //       If        |
 218 //  False  True    |
 219 //    |      |     |
 220 //  RegionNode_inputs
 221 //
 222 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
 223   top_if = NULL;
 224   bot_if = NULL;
 225 
 226   // Check control structure above RegionNode for (if  ( if  ) )
 227   Node *in1 = region->in(1);
 228   Node *in2 = region->in(2);
 229   Node *in3 = region->in(3);
 230   // Check that all inputs are projections
 231   if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
 232     Node *in10 = in1->in(0);
 233     Node *in20 = in2->in(0);
 234     Node *in30 = in3->in(0);
 235     // Check that #1 and #2 are ifTrue and ifFalse from same If
 236     if( in10 != NULL && in10->is_If() &&
 237         in20 != NULL && in20->is_If() &&
 238         in30 != NULL && in30->is_If() && in10 == in20 &&
 239         (in1->Opcode() != in2->Opcode()) ) {
 240       Node  *in100 = in10->in(0);
 241       Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
 242       // Check that control for in10 comes from other branch of IF from in3
 243       if( in1000 != NULL && in1000->is_If() &&
 244           in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
 245         // Control pattern checks
 246         top_if = (IfNode*)in1000;
 247         bot_if = (IfNode*)in10;
 248       }
 249     }
 250   }
 251 
 252   return (top_if != NULL);
 253 }
 254 
 255 
 256 //------------------------------check_convf2i_clipping-------------------------
 257 // Helper function for RegionNode's identification of FP clipping
 258 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
 259 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
 260   convf2i = NULL;
 261 
 262   // Check for the RShiftNode
 263   Node *rshift = phi->in(idx);
 264   assert( rshift, "Previous checks ensure phi input is present");
 265   if( rshift->Opcode() != Op_RShiftI )  { return false; }
 266 
 267   // Check for the LShiftNode
 268   Node *lshift = rshift->in(1);
 269   assert( lshift, "Previous checks ensure phi input is present");
 270   if( lshift->Opcode() != Op_LShiftI )  { return false; }
 271 
 272   // Check for the ConvF2INode
 273   Node *conv = lshift->in(1);
 274   if( conv->Opcode() != Op_ConvF2I ) { return false; }
 275 
 276   // Check that shift amounts are only to get sign bits set after F2I
 277   jint max_cutoff     = max->get_int();
 278   jint min_cutoff     = min->get_int();
 279   jint left_shift     = lshift->in(2)->get_int();
 280   jint right_shift    = rshift->in(2)->get_int();
 281   jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
 282   if( left_shift != right_shift ||
 283       0 > left_shift || left_shift >= BitsPerJavaInteger ||
 284       max_post_shift < max_cutoff ||
 285       max_post_shift < -min_cutoff ) {
 286     // Shifts are necessary but current transformation eliminates them
 287     return false;
 288   }
 289 
 290   // OK to return the result of ConvF2I without shifting
 291   convf2i = (ConvF2INode*)conv;
 292   return true;
 293 }
 294 
 295 
 296 //------------------------------check_compare_clipping-------------------------
 297 // Helper function for RegionNode's identification of FP clipping
 298 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
 299   Node *i1 = iff->in(1);
 300   if ( !i1->is_Bool() ) { return false; }
 301   BoolNode *bool1 = i1->as_Bool();
 302   if(       less_than && bool1->_test._test != BoolTest::le ) { return false; }
 303   else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
 304   const Node *cmpF = bool1->in(1);
 305   if( cmpF->Opcode() != Op_CmpF )      { return false; }
 306   // Test that the float value being compared against
 307   // is equivalent to the int value used as a limit
 308   Node *nodef = cmpF->in(2);
 309   if( nodef->Opcode() != Op_ConF ) { return false; }
 310   jfloat conf = nodef->getf();
 311   jint   coni = limit->get_int();
 312   if( ((int)conf) != coni )        { return false; }
 313   input = cmpF->in(1);
 314   return true;
 315 }
 316 
 317 //------------------------------is_unreachable_region--------------------------
 318 // Find if the Region node is reachable from the root.
 319 bool RegionNode::is_unreachable_region(const PhaseGVN* phase) {
 320   Node* top = phase->C->top();
 321   assert(req() == 2 || (req() == 3 && in(1) != NULL && in(2) == top), "sanity check arguments");
 322   if (_is_unreachable_region) {
 323     // Return cached result from previous evaluation which should still be valid
 324     assert(is_unreachable_from_root(phase), "walk the graph again and check if its indeed unreachable");
 325     return true;
 326   }
 327 
 328   // First, cut the simple case of fallthrough region when NONE of
 329   // region's phis references itself directly or through a data node.
 330   if (is_possible_unsafe_loop(phase)) {
 331     // If we have a possible unsafe loop, check if the region node is actually unreachable from root.
 332     if (is_unreachable_from_root(phase)) {
 333       _is_unreachable_region = true;
 334       return true;
 335     }
 336   }
 337   return false;
 338 }
 339 
 340 bool RegionNode::is_possible_unsafe_loop(const PhaseGVN* phase) const {
 341   uint max = outcnt();
 342   uint i;
 343   for (i = 0; i < max; i++) {
 344     Node* n = raw_out(i);
 345     if (n != NULL && n->is_Phi()) {
 346       PhiNode* phi = n->as_Phi();
 347       assert(phi->in(0) == this, "sanity check phi");
 348       if (phi->outcnt() == 0) {
 349         continue; // Safe case - no loops
 350       }
 351       if (phi->outcnt() == 1) {
 352         Node* u = phi->raw_out(0);
 353         // Skip if only one use is an other Phi or Call or Uncommon trap.
 354         // It is safe to consider this case as fallthrough.
 355         if (u != NULL && (u->is_Phi() || u->is_CFG())) {
 356           continue;
 357         }
 358       }
 359       // Check when phi references itself directly or through an other node.
 360       if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe) {
 361         break; // Found possible unsafe data loop.
 362       }
 363     }
 364   }
 365   if (i >= max) {
 366     return false; // An unsafe case was NOT found - don't need graph walk.
 367   }
 368   return true;
 369 }
 370 
 371 bool RegionNode::is_unreachable_from_root(const PhaseGVN* phase) const {
 372   ResourceMark rm;
 373   Node_List nstack;
 374   VectorSet visited;
 375 
 376   // Mark all control nodes reachable from root outputs
 377   Node *n = (Node*)phase->C->root();
 378   nstack.push(n);
 379   visited.set(n->_idx);
 380   while (nstack.size() != 0) {
 381     n = nstack.pop();
 382     uint max = n->outcnt();
 383     for (uint i = 0; i < max; i++) {
 384       Node* m = n->raw_out(i);
 385       if (m != NULL && m->is_CFG()) {
 386         if (m == this) {
 387           return false; // We reached the Region node - it is not dead.
 388         }
 389         if (!visited.test_set(m->_idx))
 390           nstack.push(m);
 391       }
 392     }
 393   }
 394   return true; // The Region node is unreachable - it is dead.
 395 }
 396 
 397 Node* PhiNode::try_clean_mem_phi(PhaseGVN *phase) {
 398   // Incremental inlining + PhaseStringOpts sometimes produce:
 399   //
 400   // cmpP with 1 top input
 401   //           |
 402   //          If
 403   //         /  \
 404   //   IfFalse  IfTrue  /- Some Node
 405   //         \  /      /    /
 406   //        Region    / /-MergeMem
 407   //             \---Phi
 408   //
 409   //
 410   // It's expected by PhaseStringOpts that the Region goes away and is
 411   // replaced by If's control input but because there's still a Phi,
 412   // the Region stays in the graph. The top input from the cmpP is
 413   // propagated forward and a subgraph that is useful goes away. The
 414   // code below replaces the Phi with the MergeMem so that the Region
 415   // is simplified.
 416 
 417   if (type() == Type::MEMORY && is_diamond_phi(true)) {
 418     MergeMemNode* m = NULL;
 419     assert(req() == 3, "same as region");
 420     Node* r = in(0);
 421     for (uint i = 1; i < 3; ++i) {
 422       Node *mem = in(i);
 423       if (mem && mem->is_MergeMem() && r->in(i)->outcnt() == 1) {
 424         // Nothing is control-dependent on path #i except the region itself.
 425         m = mem->as_MergeMem();
 426         uint j = 3 - i;
 427         Node* other = in(j);
 428         if (other && other == m->base_memory()) {
 429           // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
 430           // This will allow the diamond to collapse completely.
 431           return m;
 432         }
 433       }
 434     }
 435   }
 436   return NULL;
 437 }
 438 
 439 //------------------------------Ideal------------------------------------------
 440 // Return a node which is more "ideal" than the current node.  Must preserve
 441 // the CFG, but we can still strip out dead paths.
 442 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 443   if( !can_reshape && !in(0) ) return NULL;     // Already degraded to a Copy
 444   assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
 445 
 446   // Check for RegionNode with no Phi users and both inputs come from either
 447   // arm of the same IF.  If found, then the control-flow split is useless.
 448   bool has_phis = false;
 449   if (can_reshape) {            // Need DU info to check for Phi users
 450     has_phis = (has_phi() != NULL);       // Cache result
 451     if (has_phis) {
 452       PhiNode* phi = has_unique_phi();
 453       if (phi != NULL) {
 454         Node* m = phi->try_clean_mem_phi(phase);
 455         if (m != NULL) {
 456           phase->is_IterGVN()->replace_node(phi, m);
 457           has_phis = false;
 458         }
 459       }
 460     }
 461 
 462     if (!has_phis) {            // No Phi users?  Nothing merging?
 463       for (uint i = 1; i < req()-1; i++) {
 464         Node *if1 = in(i);
 465         if( !if1 ) continue;
 466         Node *iff = if1->in(0);
 467         if( !iff || !iff->is_If() ) continue;
 468         for( uint j=i+1; j<req(); j++ ) {
 469           if( in(j) && in(j)->in(0) == iff &&
 470               if1->Opcode() != in(j)->Opcode() ) {
 471             // Add the IF Projections to the worklist. They (and the IF itself)
 472             // will be eliminated if dead.
 473             phase->is_IterGVN()->add_users_to_worklist(iff);
 474             set_req(i, iff->in(0));// Skip around the useless IF diamond
 475             set_req(j, NULL);
 476             return this;      // Record progress
 477           }
 478         }
 479       }
 480     }
 481   }
 482 
 483   // Remove TOP or NULL input paths. If only 1 input path remains, this Region
 484   // degrades to a copy.
 485   bool add_to_worklist = false;
 486   bool modified = false;
 487   int cnt = 0;                  // Count of values merging
 488   DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
 489   int del_it = 0;               // The last input path we delete
 490   // For all inputs...
 491   for( uint i=1; i<req(); ++i ){// For all paths in
 492     Node *n = in(i);            // Get the input
 493     if( n != NULL ) {
 494       // Remove useless control copy inputs
 495       if( n->is_Region() && n->as_Region()->is_copy() ) {
 496         set_req(i, n->nonnull_req());
 497         modified = true;
 498         i--;
 499         continue;
 500       }
 501       if( n->is_Proj() ) {      // Remove useless rethrows
 502         Node *call = n->in(0);
 503         if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
 504           set_req(i, call->in(0));
 505           modified = true;
 506           i--;
 507           continue;
 508         }
 509       }
 510       if( phase->type(n) == Type::TOP ) {
 511         set_req(i, NULL);       // Ignore TOP inputs
 512         modified = true;
 513         i--;
 514         continue;
 515       }
 516       cnt++;                    // One more value merging
 517 
 518     } else if (can_reshape) {   // Else found dead path with DU info
 519       PhaseIterGVN *igvn = phase->is_IterGVN();
 520       del_req(i);               // Yank path from self
 521       del_it = i;
 522       uint max = outcnt();
 523       DUIterator j;
 524       bool progress = true;
 525       while(progress) {         // Need to establish property over all users
 526         progress = false;
 527         for (j = outs(); has_out(j); j++) {
 528           Node *n = out(j);
 529           if( n->req() != req() && n->is_Phi() ) {
 530             assert( n->in(0) == this, "" );
 531             igvn->hash_delete(n); // Yank from hash before hacking edges
 532             n->set_req_X(i,NULL,igvn);// Correct DU info
 533             n->del_req(i);        // Yank path from Phis
 534             if( max != outcnt() ) {
 535               progress = true;
 536               j = refresh_out_pos(j);
 537               max = outcnt();
 538             }
 539           }
 540         }
 541       }
 542       add_to_worklist = true;
 543       i--;
 544     }
 545   }
 546 
 547   if (can_reshape && cnt == 1) {
 548     // Is it dead loop?
 549     // If it is LoopNopde it had 2 (+1 itself) inputs and
 550     // one of them was cut. The loop is dead if it was EntryContol.
 551     // Loop node may have only one input because entry path
 552     // is removed in PhaseIdealLoop::Dominators().
 553     assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
 554     if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
 555                              (del_it == 0 && is_unreachable_region(phase)))) ||
 556         (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
 557       // Yes,  the region will be removed during the next step below.
 558       // Cut the backedge input and remove phis since no data paths left.
 559       // We don't cut outputs to other nodes here since we need to put them
 560       // on the worklist.
 561       PhaseIterGVN *igvn = phase->is_IterGVN();
 562       if (in(1)->outcnt() == 1) {
 563         igvn->_worklist.push(in(1));
 564       }
 565       del_req(1);
 566       cnt = 0;
 567       assert( req() == 1, "no more inputs expected" );
 568       uint max = outcnt();
 569       bool progress = true;
 570       Node *top = phase->C->top();
 571       DUIterator j;
 572       while(progress) {
 573         progress = false;
 574         for (j = outs(); has_out(j); j++) {
 575           Node *n = out(j);
 576           if( n->is_Phi() ) {
 577             assert(n->in(0) == this, "");
 578             assert( n->req() == 2 &&  n->in(1) != NULL, "Only one data input expected" );
 579             // Break dead loop data path.
 580             // Eagerly replace phis with top to avoid regionless phis.
 581             igvn->replace_node(n, top);
 582             if( max != outcnt() ) {
 583               progress = true;
 584               j = refresh_out_pos(j);
 585               max = outcnt();
 586             }
 587           }
 588         }
 589       }
 590       add_to_worklist = true;
 591     }
 592   }
 593   if (add_to_worklist) {
 594     phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
 595   }
 596 
 597   if( cnt <= 1 ) {              // Only 1 path in?
 598     set_req(0, NULL);           // Null control input for region copy
 599     if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
 600       // No inputs or all inputs are NULL.
 601       return NULL;
 602     } else if (can_reshape) {   // Optimization phase - remove the node
 603       PhaseIterGVN *igvn = phase->is_IterGVN();
 604       // Strip mined (inner) loop is going away, remove outer loop.
 605       if (is_CountedLoop() &&
 606           as_Loop()->is_strip_mined()) {
 607         Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
 608         Node* outer_out = as_CountedLoop()->outer_loop_exit();
 609         if (outer_sfpt != NULL && outer_out != NULL) {
 610           Node* in = outer_sfpt->in(0);
 611           igvn->replace_node(outer_out, in);
 612           LoopNode* outer = as_CountedLoop()->outer_loop();
 613           igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
 614         }
 615       }
 616       if (is_CountedLoop()) {
 617         Node* opaq = as_CountedLoop()->is_canonical_loop_entry();
 618         if (opaq != NULL) {
 619           // This is not a loop anymore. No need to keep the Opaque1 node on the test that guards the loop as it won't be
 620           // subject to further loop opts.
 621           assert(opaq->Opcode() == Op_Opaque1, "");
 622           igvn->replace_node(opaq, opaq->in(1));
 623         }
 624       }
 625       Node *parent_ctrl;
 626       if( cnt == 0 ) {
 627         assert( req() == 1, "no inputs expected" );
 628         // During IGVN phase such region will be subsumed by TOP node
 629         // so region's phis will have TOP as control node.
 630         // Kill phis here to avoid it.
 631         // Also set other user's input to top.
 632         parent_ctrl = phase->C->top();
 633       } else {
 634         // The fallthrough case since we already checked dead loops above.
 635         parent_ctrl = in(1);
 636         assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
 637         assert(parent_ctrl != this, "Close dead loop");
 638       }
 639       if (!add_to_worklist)
 640         igvn->add_users_to_worklist(this); // Check for further allowed opts
 641       for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
 642         Node* n = last_out(i);
 643         igvn->hash_delete(n); // Remove from worklist before modifying edges
 644         if (n->outcnt() == 0) {
 645           int uses_found = n->replace_edge(this, phase->C->top(), igvn);
 646           if (uses_found > 1) { // (--i) done at the end of the loop.
 647             i -= (uses_found - 1);
 648           }
 649           continue;
 650         }
 651         if( n->is_Phi() ) {   // Collapse all Phis
 652           // Eagerly replace phis to avoid regionless phis.
 653           Node* in;
 654           if( cnt == 0 ) {
 655             assert( n->req() == 1, "No data inputs expected" );
 656             in = parent_ctrl; // replaced by top
 657           } else {
 658             assert( n->req() == 2 &&  n->in(1) != NULL, "Only one data input expected" );
 659             in = n->in(1);               // replaced by unique input
 660             if( n->as_Phi()->is_unsafe_data_reference(in) )
 661               in = phase->C->top();      // replaced by top
 662           }
 663           igvn->replace_node(n, in);
 664         }
 665         else if( n->is_Region() ) { // Update all incoming edges
 666           assert(n != this, "Must be removed from DefUse edges");
 667           int uses_found = n->replace_edge(this, parent_ctrl, igvn);
 668           if (uses_found > 1) { // (--i) done at the end of the loop.
 669             i -= (uses_found - 1);
 670           }
 671         }
 672         else {
 673           assert(n->in(0) == this, "Expect RegionNode to be control parent");
 674           n->set_req(0, parent_ctrl);
 675         }
 676 #ifdef ASSERT
 677         for( uint k=0; k < n->req(); k++ ) {
 678           assert(n->in(k) != this, "All uses of RegionNode should be gone");
 679         }
 680 #endif
 681       }
 682       // Remove the RegionNode itself from DefUse info
 683       igvn->remove_dead_node(this);
 684       return NULL;
 685     }
 686     return this;                // Record progress
 687   }
 688 
 689 
 690   // If a Region flows into a Region, merge into one big happy merge.
 691   if (can_reshape) {
 692     Node *m = merge_region(this, phase);
 693     if (m != NULL)  return m;
 694   }
 695 
 696   // Check if this region is the root of a clipping idiom on floats
 697   if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
 698     // Check that only one use is a Phi and that it simplifies to two constants +
 699     PhiNode* phi = has_unique_phi();
 700     if (phi != NULL) {          // One Phi user
 701       // Check inputs to the Phi
 702       ConNode *min;
 703       ConNode *max;
 704       Node    *val;
 705       uint     min_idx;
 706       uint     max_idx;
 707       uint     val_idx;
 708       if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx )  ) {
 709         IfNode *top_if;
 710         IfNode *bot_if;
 711         if( check_if_clipping( this, bot_if, top_if ) ) {
 712           // Control pattern checks, now verify compares
 713           Node   *top_in = NULL;   // value being compared against
 714           Node   *bot_in = NULL;
 715           if( check_compare_clipping( true,  bot_if, min, bot_in ) &&
 716               check_compare_clipping( false, top_if, max, top_in ) ) {
 717             if( bot_in == top_in ) {
 718               PhaseIterGVN *gvn = phase->is_IterGVN();
 719               assert( gvn != NULL, "Only had DefUse info in IterGVN");
 720               // Only remaining check is that bot_in == top_in == (Phi's val + mods)
 721 
 722               // Check for the ConvF2INode
 723               ConvF2INode *convf2i;
 724               if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
 725                 convf2i->in(1) == bot_in ) {
 726                 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
 727                 // max test
 728                 Node *cmp   = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
 729                 Node *boo   = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
 730                 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
 731                 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
 732                 Node *ifF   = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
 733                 // min test
 734                 cmp         = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
 735                 boo         = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
 736                 iff         = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
 737                 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
 738                 ifF         = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
 739                 // update input edges to region node
 740                 set_req_X( min_idx, if_min, gvn );
 741                 set_req_X( max_idx, if_max, gvn );
 742                 set_req_X( val_idx, ifF,    gvn );
 743                 // remove unnecessary 'LShiftI; RShiftI' idiom
 744                 gvn->hash_delete(phi);
 745                 phi->set_req_X( val_idx, convf2i, gvn );
 746                 gvn->hash_find_insert(phi);
 747                 // Return transformed region node
 748                 return this;
 749               }
 750             }
 751           }
 752         }
 753       }
 754     }
 755   }
 756 
 757   if (can_reshape) {
 758     modified |= optimize_trichotomy(phase->is_IterGVN());
 759   }
 760 
 761   return modified ? this : NULL;
 762 }
 763 
 764 //------------------------------optimize_trichotomy--------------------------
 765 // Optimize nested comparisons of the following kind:
 766 //
 767 // int compare(int a, int b) {
 768 //   return (a < b) ? -1 : (a == b) ? 0 : 1;
 769 // }
 770 //
 771 // Shape 1:
 772 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
 773 //
 774 // Shape 2:
 775 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
 776 //
 777 // Above code leads to the following IR shapes where both Ifs compare the
 778 // same value and two out of three region inputs idx1 and idx2 map to
 779 // the same value and control flow.
 780 //
 781 // (1)   If                 (2)   If
 782 //      /  \                     /  \
 783 //   Proj  Proj               Proj  Proj
 784 //     |      \                |      \
 785 //     |       If              |      If                      If
 786 //     |      /  \             |     /  \                    /  \
 787 //     |   Proj  Proj          |  Proj  Proj      ==>     Proj  Proj
 788 //     |   /      /            \    |    /                  |    /
 789 //    Region     /              \   |   /                   |   /
 790 //         \    /                \  |  /                    |  /
 791 //         Region                Region                    Region
 792 //
 793 // The method returns true if 'this' is modified and false otherwise.
 794 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
 795   int idx1 = 1, idx2 = 2;
 796   Node* region = NULL;
 797   if (req() == 3 && in(1) != NULL && in(2) != NULL) {
 798     // Shape 1: Check if one of the inputs is a region that merges two control
 799     // inputs and has no other users (especially no Phi users).
 800     region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
 801     if (region == NULL || region->outcnt() != 2 || region->req() != 3) {
 802       return false; // No suitable region input found
 803     }
 804   } else if (req() == 4) {
 805     // Shape 2: Check if two control inputs map to the same value of the unique phi
 806     // user and treat these as if they would come from another region (shape (1)).
 807     PhiNode* phi = has_unique_phi();
 808     if (phi == NULL) {
 809       return false; // No unique phi user
 810     }
 811     if (phi->in(idx1) != phi->in(idx2)) {
 812       idx2 = 3;
 813       if (phi->in(idx1) != phi->in(idx2)) {
 814         idx1 = 2;
 815         if (phi->in(idx1) != phi->in(idx2)) {
 816           return false; // No equal phi inputs found
 817         }
 818       }
 819     }
 820     assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
 821     region = this;
 822   }
 823   if (region == NULL || region->in(idx1) == NULL || region->in(idx2) == NULL) {
 824     return false; // Region does not merge two control inputs
 825   }
 826   // At this point we know that region->in(idx1) and region->(idx2) map to the same
 827   // value and control flow. Now search for ifs that feed into these region inputs.
 828   ProjNode* proj1 = region->in(idx1)->isa_Proj();
 829   ProjNode* proj2 = region->in(idx2)->isa_Proj();
 830   if (proj1 == NULL || proj1->outcnt() != 1 ||
 831       proj2 == NULL || proj2->outcnt() != 1) {
 832     return false; // No projection inputs with region as unique user found
 833   }
 834   assert(proj1 != proj2, "should be different projections");
 835   IfNode* iff1 = proj1->in(0)->isa_If();
 836   IfNode* iff2 = proj2->in(0)->isa_If();
 837   if (iff1 == NULL || iff1->outcnt() != 2 ||
 838       iff2 == NULL || iff2->outcnt() != 2) {
 839     return false; // No ifs found
 840   }
 841   if (iff1 == iff2) {
 842     igvn->add_users_to_worklist(iff1); // Make sure dead if is eliminated
 843     igvn->replace_input_of(region, idx1, iff1->in(0));
 844     igvn->replace_input_of(region, idx2, igvn->C->top());
 845     return (region == this); // Remove useless if (both projections map to the same control/value)
 846   }
 847   BoolNode* bol1 = iff1->in(1)->isa_Bool();
 848   BoolNode* bol2 = iff2->in(1)->isa_Bool();
 849   if (bol1 == NULL || bol2 == NULL) {
 850     return false; // No bool inputs found
 851   }
 852   Node* cmp1 = bol1->in(1);
 853   Node* cmp2 = bol2->in(1);
 854   bool commute = false;
 855   if (!cmp1->is_Cmp() || !cmp2->is_Cmp()) {
 856     return false; // No comparison
 857   } else if (cmp1->Opcode() == Op_CmpF || cmp1->Opcode() == Op_CmpD ||
 858              cmp2->Opcode() == Op_CmpF || cmp2->Opcode() == Op_CmpD ||
 859              cmp1->Opcode() == Op_CmpP || cmp1->Opcode() == Op_CmpN ||
 860              cmp2->Opcode() == Op_CmpP || cmp2->Opcode() == Op_CmpN ||
 861              cmp1->is_SubTypeCheck() || cmp2->is_SubTypeCheck() ||
 862              cmp1->is_FlatArrayCheck() || cmp2->is_FlatArrayCheck()) {
 863     // Floats and pointers don't exactly obey trichotomy. To be on the safe side, don't transform their tests.
 864     // SubTypeCheck is not commutative
 865     return false;
 866   } else if (cmp1 != cmp2) {
 867     if (cmp1->in(1) == cmp2->in(2) &&
 868         cmp1->in(2) == cmp2->in(1)) {
 869       commute = true; // Same but swapped inputs, commute the test
 870     } else {
 871       return false; // Ifs are not comparing the same values
 872     }
 873   }
 874   proj1 = proj1->other_if_proj();
 875   proj2 = proj2->other_if_proj();
 876   if (!((proj1->unique_ctrl_out() == iff2 &&
 877          proj2->unique_ctrl_out() == this) ||
 878         (proj2->unique_ctrl_out() == iff1 &&
 879          proj1->unique_ctrl_out() == this))) {
 880     return false; // Ifs are not connected through other projs
 881   }
 882   // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
 883   // through 'region' and map to the same value. Merge the boolean tests and replace
 884   // the ifs by a single comparison.
 885   BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
 886   BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
 887   test1 = commute ? test1.commute() : test1;
 888   // After possibly commuting test1, if we can merge test1 & test2, then proj2/iff2/bol2 are the nodes to refine.
 889   BoolTest::mask res = test1.merge(test2);
 890   if (res == BoolTest::illegal) {
 891     return false; // Unable to merge tests
 892   }
 893   // Adjust iff1 to always pass (only iff2 will remain)
 894   igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
 895   if (res == BoolTest::never) {
 896     // Merged test is always false, adjust iff2 to always fail
 897     igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
 898   } else {
 899     // Replace bool input of iff2 with merged test
 900     BoolNode* new_bol = new BoolNode(bol2->in(1), res);
 901     igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
 902     if (new_bol->outcnt() == 0) {
 903       igvn->remove_dead_node(new_bol);
 904     }
 905   }
 906   return false;
 907 }
 908 
 909 const RegMask &RegionNode::out_RegMask() const {
 910   return RegMask::Empty;
 911 }
 912 
 913 // Find the one non-null required input.  RegionNode only
 914 Node *Node::nonnull_req() const {
 915   assert( is_Region(), "" );
 916   for( uint i = 1; i < _cnt; i++ )
 917     if( in(i) )
 918       return in(i);
 919   ShouldNotReachHere();
 920   return NULL;
 921 }
 922 
 923 
 924 //=============================================================================
 925 // note that these functions assume that the _adr_type field is flattened
 926 uint PhiNode::hash() const {
 927   const Type* at = _adr_type;
 928   return TypeNode::hash() + (at ? at->hash() : 0);
 929 }
 930 bool PhiNode::cmp( const Node &n ) const {
 931   return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
 932 }
 933 static inline
 934 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
 935   if (at == NULL || at == TypePtr::BOTTOM)  return at;
 936   return Compile::current()->alias_type(at)->adr_type();
 937 }
 938 
 939 //----------------------------make---------------------------------------------
 940 // create a new phi with edges matching r and set (initially) to x
 941 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
 942   uint preds = r->req();   // Number of predecessor paths
 943   assert(t != Type::MEMORY || at == flatten_phi_adr_type(at) || (flatten_phi_adr_type(at) == TypeAryPtr::INLINES && Compile::current()->flattened_accesses_share_alias()), "flatten at");
 944   PhiNode* p = new PhiNode(r, t, at);
 945   for (uint j = 1; j < preds; j++) {
 946     // Fill in all inputs, except those which the region does not yet have
 947     if (r->in(j) != NULL)
 948       p->init_req(j, x);
 949   }
 950   return p;
 951 }
 952 PhiNode* PhiNode::make(Node* r, Node* x) {
 953   const Type*    t  = x->bottom_type();
 954   const TypePtr* at = NULL;
 955   if (t == Type::MEMORY)  at = flatten_phi_adr_type(x->adr_type());
 956   return make(r, x, t, at);
 957 }
 958 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
 959   const Type*    t  = x->bottom_type();
 960   const TypePtr* at = NULL;
 961   if (t == Type::MEMORY)  at = flatten_phi_adr_type(x->adr_type());
 962   return new PhiNode(r, t, at);
 963 }
 964 
 965 
 966 //------------------------slice_memory-----------------------------------------
 967 // create a new phi with narrowed memory type
 968 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
 969   PhiNode* mem = (PhiNode*) clone();
 970   *(const TypePtr**)&mem->_adr_type = adr_type;
 971   // convert self-loops, or else we get a bad graph
 972   for (uint i = 1; i < req(); i++) {
 973     if ((const Node*)in(i) == this)  mem->set_req(i, mem);
 974   }
 975   mem->verify_adr_type();
 976   return mem;
 977 }
 978 
 979 //------------------------split_out_instance-----------------------------------
 980 // Split out an instance type from a bottom phi.
 981 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
 982   const TypeOopPtr *t_oop = at->isa_oopptr();
 983   assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
 984   const TypePtr *t = adr_type();
 985   assert(type() == Type::MEMORY &&
 986          (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
 987           t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
 988           t->is_oopptr()->cast_to_exactness(true)
 989            ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
 990            ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
 991          "bottom or raw memory required");
 992 
 993   // Check if an appropriate node already exists.
 994   Node *region = in(0);
 995   for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
 996     Node* use = region->fast_out(k);
 997     if( use->is_Phi()) {
 998       PhiNode *phi2 = use->as_Phi();
 999       if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
1000         return phi2;
1001       }
1002     }
1003   }
1004   Compile *C = igvn->C;
1005   Arena *a = Thread::current()->resource_area();
1006   Node_Array node_map = new Node_Array(a);
1007   Node_Stack stack(a, C->live_nodes() >> 4);
1008   PhiNode *nphi = slice_memory(at);
1009   igvn->register_new_node_with_optimizer( nphi );
1010   node_map.map(_idx, nphi);
1011   stack.push((Node *)this, 1);
1012   while(!stack.is_empty()) {
1013     PhiNode *ophi = stack.node()->as_Phi();
1014     uint i = stack.index();
1015     assert(i >= 1, "not control edge");
1016     stack.pop();
1017     nphi = node_map[ophi->_idx]->as_Phi();
1018     for (; i < ophi->req(); i++) {
1019       Node *in = ophi->in(i);
1020       if (in == NULL || igvn->type(in) == Type::TOP)
1021         continue;
1022       Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
1023       PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
1024       if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
1025         opt = node_map[optphi->_idx];
1026         if (opt == NULL) {
1027           stack.push(ophi, i);
1028           nphi = optphi->slice_memory(at);
1029           igvn->register_new_node_with_optimizer( nphi );
1030           node_map.map(optphi->_idx, nphi);
1031           ophi = optphi;
1032           i = 0; // will get incremented at top of loop
1033           continue;
1034         }
1035       }
1036       nphi->set_req(i, opt);
1037     }
1038   }
1039   return nphi;
1040 }
1041 
1042 //------------------------verify_adr_type--------------------------------------
1043 #ifdef ASSERT
1044 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
1045   if (visited.test_set(_idx))  return;  //already visited
1046 
1047   // recheck constructor invariants:
1048   verify_adr_type(false);
1049 
1050   // recheck local phi/phi consistency:
1051   assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
1052          "adr_type must be consistent across phi nest");
1053 
1054   // walk around
1055   for (uint i = 1; i < req(); i++) {
1056     Node* n = in(i);
1057     if (n == NULL)  continue;
1058     const Node* np = in(i);
1059     if (np->is_Phi()) {
1060       np->as_Phi()->verify_adr_type(visited, at);
1061     } else if (n->bottom_type() == Type::TOP
1062                || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
1063       // ignore top inputs
1064     } else {
1065       const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
1066       // recheck phi/non-phi consistency at leaves:
1067       assert((nat != NULL) == (at != NULL), "");
1068       assert(nat == at || nat == TypePtr::BOTTOM,
1069              "adr_type must be consistent at leaves of phi nest");
1070     }
1071   }
1072 }
1073 
1074 // Verify a whole nest of phis rooted at this one.
1075 void PhiNode::verify_adr_type(bool recursive) const {
1076   if (VMError::is_error_reported())  return;  // muzzle asserts when debugging an error
1077   if (Node::in_dump())               return;  // muzzle asserts when printing
1078 
1079   assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
1080   // Flat array element shouldn't get their own memory slice until flattened_accesses_share_alias is cleared.
1081   // It could be the graph has no loads/stores and flattened_accesses_share_alias is never cleared. EA could still
1082   // creates per element Phis but that wouldn't be a problem as there are no memory accesses for that array.
1083   assert(_adr_type == NULL || _adr_type->isa_aryptr() == NULL ||
1084          _adr_type->is_aryptr()->is_known_instance() ||
1085          !_adr_type->is_aryptr()->is_flat() ||
1086          !Compile::current()->flattened_accesses_share_alias() ||
1087          _adr_type == TypeAryPtr::INLINES, "flat array element shouldn't get its own slice yet");
1088 
1089   if (!VerifyAliases)       return;  // verify thoroughly only if requested
1090 
1091   assert(_adr_type == flatten_phi_adr_type(_adr_type),
1092          "Phi::adr_type must be pre-normalized");
1093 
1094   if (recursive) {
1095     VectorSet visited;
1096     verify_adr_type(visited, _adr_type);
1097   }
1098 }
1099 #endif
1100 
1101 
1102 //------------------------------Value------------------------------------------
1103 // Compute the type of the PhiNode
1104 const Type* PhiNode::Value(PhaseGVN* phase) const {
1105   Node *r = in(0);              // RegionNode
1106   if( !r )                      // Copy or dead
1107     return in(1) ? phase->type(in(1)) : Type::TOP;
1108 
1109   // Note: During parsing, phis are often transformed before their regions.
1110   // This means we have to use type_or_null to defend against untyped regions.
1111   if( phase->type_or_null(r) == Type::TOP )  // Dead code?
1112     return Type::TOP;
1113 
1114   // Check for trip-counted loop.  If so, be smarter.
1115   BaseCountedLoopNode* l = r->is_BaseCountedLoop() ? r->as_BaseCountedLoop() : NULL;
1116   if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1117     // protect against init_trip() or limit() returning NULL
1118     if (l->can_be_counted_loop(phase)) {
1119       const Node* init = l->init_trip();
1120       const Node* limit = l->limit();
1121       const Node* stride = l->stride();
1122       if (init != NULL && limit != NULL && stride != NULL) {
1123         const TypeInteger* lo = phase->type(init)->isa_integer(l->bt());
1124         const TypeInteger* hi = phase->type(limit)->isa_integer(l->bt());
1125         const TypeInteger* stride_t = phase->type(stride)->isa_integer(l->bt());
1126         if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
1127           assert(stride_t->hi_as_long() >= stride_t->lo_as_long(), "bad stride type");
1128           BoolTest::mask bt = l->loopexit()->test_trip();
1129           // If the loop exit condition is "not equal", the condition
1130           // would not trigger if init > limit (if stride > 0) or if
1131           // init < limit if (stride > 0) so we can't deduce bounds
1132           // for the iv from the exit condition.
1133           if (bt != BoolTest::ne) {
1134             if (stride_t->hi_as_long() < 0) {          // Down-counter loop
1135               swap(lo, hi);
1136               return TypeInteger::make(MIN2(lo->lo_as_long(), hi->lo_as_long()), hi->hi_as_long(), 3, l->bt())->filter_speculative(_type);
1137             } else if (stride_t->lo_as_long() >= 0) {
1138               return TypeInteger::make(lo->lo_as_long(), MAX2(lo->hi_as_long(), hi->hi_as_long()), 3, l->bt())->filter_speculative(_type);
1139             }
1140           }
1141         }
1142       }
1143     } else if (l->in(LoopNode::LoopBackControl) != NULL &&
1144                in(LoopNode::EntryControl) != NULL &&
1145                phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1146       // During CCP, if we saturate the type of a counted loop's Phi
1147       // before the special code for counted loop above has a chance
1148       // to run (that is as long as the type of the backedge's control
1149       // is top), we might end up with non monotonic types
1150       return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1151     }
1152   }
1153 
1154   // Until we have harmony between classes and interfaces in the type
1155   // lattice, we must tread carefully around phis which implicitly
1156   // convert the one to the other.
1157   const TypePtr* ttp = _type->make_ptr();
1158   const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
1159   const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_instklassptr() : NULL;
1160   bool is_intf = false;
1161   if (ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1162     is_intf = true;
1163   } else if (ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1164     is_intf = true;
1165   }
1166 
1167   // Default case: merge all inputs
1168   const Type *t = Type::TOP;        // Merged type starting value
1169   for (uint i = 1; i < req(); ++i) {// For all paths in
1170     // Reachable control path?
1171     if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1172       const Type* ti = phase->type(in(i));
1173       // We assume that each input of an interface-valued Phi is a true
1174       // subtype of that interface.  This might not be true of the meet
1175       // of all the input types.  The lattice is not distributive in
1176       // such cases.  Ward off asserts in type.cpp by refusing to do
1177       // meets between interfaces and proper classes.
1178       const TypePtr* tip = ti->make_ptr();
1179       const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
1180       if (tiip) {
1181         bool ti_is_intf = false;
1182         ciKlass* k = tiip->klass();
1183         if (k->is_loaded() && k->is_interface())
1184           ti_is_intf = true;
1185         if (is_intf != ti_is_intf)
1186           { t = _type; break; }
1187       }
1188       t = t->meet_speculative(ti);
1189     }
1190   }
1191 
1192   // The worst-case type (from ciTypeFlow) should be consistent with "t".
1193   // That is, we expect that "t->higher_equal(_type)" holds true.
1194   // There are various exceptions:
1195   // - Inputs which are phis might in fact be widened unnecessarily.
1196   //   For example, an input might be a widened int while the phi is a short.
1197   // - Inputs might be BotPtrs but this phi is dependent on a null check,
1198   //   and postCCP has removed the cast which encodes the result of the check.
1199   // - The type of this phi is an interface, and the inputs are classes.
1200   // - Value calls on inputs might produce fuzzy results.
1201   //   (Occurrences of this case suggest improvements to Value methods.)
1202   //
1203   // It is not possible to see Type::BOTTOM values as phi inputs,
1204   // because the ciTypeFlow pre-pass produces verifier-quality types.
1205   const Type* ft = t->filter_speculative(_type);  // Worst case type
1206 
1207 #ifdef ASSERT
1208   // The following logic has been moved into TypeOopPtr::filter.
1209   const Type* jt = t->join_speculative(_type);
1210   if (jt->empty()) {           // Emptied out???
1211 
1212     // Check for evil case of 't' being a class and '_type' expecting an
1213     // interface.  This can happen because the bytecodes do not contain
1214     // enough type info to distinguish a Java-level interface variable
1215     // from a Java-level object variable.  If we meet 2 classes which
1216     // both implement interface I, but their meet is at 'j/l/O' which
1217     // doesn't implement I, we have no way to tell if the result should
1218     // be 'I' or 'j/l/O'.  Thus we'll pick 'j/l/O'.  If this then flows
1219     // into a Phi which "knows" it's an Interface type we'll have to
1220     // uplift the type.
1221     if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1222       assert(ft == _type, ""); // Uplift to interface
1223     } else if (!t->empty() && ttkp != NULL && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1224       assert(ft == _type, ""); // Uplift to interface
1225     } else {
1226       // We also have to handle 'evil cases' of interface- vs. class-arrays
1227       Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1228       if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1229           assert(ft == _type, "");   // Uplift to array of interface
1230       } else {
1231         // Otherwise it's something stupid like non-overlapping int ranges
1232         // found on dying counted loops.
1233         assert(ft == Type::TOP, ""); // Canonical empty value
1234       }
1235     }
1236   }
1237 
1238   else {
1239 
1240     // If we have an interface-typed Phi and we narrow to a class type, the join
1241     // should report back the class.  However, if we have a J/L/Object
1242     // class-typed Phi and an interface flows in, it's possible that the meet &
1243     // join report an interface back out.  This isn't possible but happens
1244     // because the type system doesn't interact well with interfaces.
1245     const TypePtr *jtp = jt->make_ptr();
1246     const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1247     const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_instklassptr() : NULL;
1248     if( jtip && ttip ) {
1249       if( jtip->is_loaded() &&  jtip->klass()->is_interface() &&
1250           ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1251         assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1252                ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1253         jt = ft;
1254       }
1255     }
1256     if( jtkp && ttkp ) {
1257       if( jtkp->is_loaded() &&  jtkp->klass()->is_interface() &&
1258           !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1259           ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1260         assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1261                ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1262         jt = ft;
1263       }
1264     }
1265     if (jt != ft && jt->base() == ft->base()) {
1266       if (jt->isa_int() &&
1267           jt->is_int()->_lo == ft->is_int()->_lo &&
1268           jt->is_int()->_hi == ft->is_int()->_hi)
1269         jt = ft;
1270       if (jt->isa_long() &&
1271           jt->is_long()->_lo == ft->is_long()->_lo &&
1272           jt->is_long()->_hi == ft->is_long()->_hi)
1273         jt = ft;
1274     }
1275     if (jt != ft) {
1276       tty->print("merge type:  "); t->dump(); tty->cr();
1277       tty->print("kill type:   "); _type->dump(); tty->cr();
1278       tty->print("join type:   "); jt->dump(); tty->cr();
1279       tty->print("filter type: "); ft->dump(); tty->cr();
1280     }
1281     assert(jt == ft, "");
1282   }
1283 #endif //ASSERT
1284 
1285   // Deal with conversion problems found in data loops.
1286   ft = phase->saturate(ft, phase->type_or_null(this), _type);
1287 
1288   return ft;
1289 }
1290 
1291 
1292 //------------------------------is_diamond_phi---------------------------------
1293 // Does this Phi represent a simple well-shaped diamond merge?  Return the
1294 // index of the true path or 0 otherwise.
1295 // If check_control_only is true, do not inspect the If node at the
1296 // top, and return -1 (not an edge number) on success.
1297 int PhiNode::is_diamond_phi(bool check_control_only) const {
1298   // Check for a 2-path merge
1299   Node *region = in(0);
1300   if( !region ) return 0;
1301   if( region->req() != 3 ) return 0;
1302   if(         req() != 3 ) return 0;
1303   // Check that both paths come from the same If
1304   Node *ifp1 = region->in(1);
1305   Node *ifp2 = region->in(2);
1306   if( !ifp1 || !ifp2 ) return 0;
1307   Node *iff = ifp1->in(0);
1308   if( !iff || !iff->is_If() ) return 0;
1309   if( iff != ifp2->in(0) ) return 0;
1310   if (check_control_only)  return -1;
1311   // Check for a proper bool/cmp
1312   const Node *b = iff->in(1);
1313   if( !b->is_Bool() ) return 0;
1314   const Node *cmp = b->in(1);
1315   if( !cmp->is_Cmp() ) return 0;
1316 
1317   // Check for branching opposite expected
1318   if( ifp2->Opcode() == Op_IfTrue ) {
1319     assert( ifp1->Opcode() == Op_IfFalse, "" );
1320     return 2;
1321   } else {
1322     assert( ifp1->Opcode() == Op_IfTrue, "" );
1323     return 1;
1324   }
1325 }
1326 
1327 //----------------------------check_cmove_id-----------------------------------
1328 // Check for CMove'ing a constant after comparing against the constant.
1329 // Happens all the time now, since if we compare equality vs a constant in
1330 // the parser, we "know" the variable is constant on one path and we force
1331 // it.  Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1332 // conditional move: "x = (x==0)?0:x;".  Yucko.  This fix is slightly more
1333 // general in that we don't need constants.  Since CMove's are only inserted
1334 // in very special circumstances, we do it here on generic Phi's.
1335 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1336   assert(true_path !=0, "only diamond shape graph expected");
1337 
1338   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1339   // phi->region->if_proj->ifnode->bool->cmp
1340   Node*     region = in(0);
1341   Node*     iff    = region->in(1)->in(0);
1342   BoolNode* b      = iff->in(1)->as_Bool();
1343   Node*     cmp    = b->in(1);
1344   Node*     tval   = in(true_path);
1345   Node*     fval   = in(3-true_path);
1346   Node*     id     = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1347   if (id == NULL)
1348     return NULL;
1349 
1350   // Either value might be a cast that depends on a branch of 'iff'.
1351   // Since the 'id' value will float free of the diamond, either
1352   // decast or return failure.
1353   Node* ctl = id->in(0);
1354   if (ctl != NULL && ctl->in(0) == iff) {
1355     if (id->is_ConstraintCast()) {
1356       return id->in(1);
1357     } else {
1358       // Don't know how to disentangle this value.
1359       return NULL;
1360     }
1361   }
1362 
1363   return id;
1364 }
1365 
1366 //------------------------------Identity---------------------------------------
1367 // Check for Region being Identity.
1368 Node* PhiNode::Identity(PhaseGVN* phase) {
1369   // Check for no merging going on
1370   // (There used to be special-case code here when this->region->is_Loop.
1371   // It would check for a tributary phi on the backedge that the main phi
1372   // trivially, perhaps with a single cast.  The unique_input method
1373   // does all this and more, by reducing such tributaries to 'this'.)
1374   Node* uin = unique_input(phase, false);
1375   if (uin != NULL) {
1376     return uin;
1377   }
1378 
1379   int true_path = is_diamond_phi();
1380   if (true_path != 0) {
1381     Node* id = is_cmove_id(phase, true_path);
1382     if (id != NULL)  return id;
1383   }
1384 
1385   if (phase->is_IterGVN()) {
1386     Node* m = try_clean_mem_phi(phase);
1387     if (m != NULL) {
1388       return m;
1389     }
1390   }
1391 
1392 
1393   // Looking for phis with identical inputs.  If we find one that has
1394   // type TypePtr::BOTTOM, replace the current phi with the bottom phi.
1395   if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() !=
1396       TypePtr::BOTTOM && !adr_type()->is_known_instance()) {
1397     uint phi_len = req();
1398     Node* phi_reg = region();
1399     for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) {
1400       Node* u = phi_reg->fast_out(i);
1401       if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY &&
1402           u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg &&
1403           u->req() == phi_len) {
1404         for (uint j = 1; j < phi_len; j++) {
1405           if (in(j) != u->in(j)) {
1406             u = NULL;
1407             break;
1408           }
1409         }
1410         if (u != NULL) {
1411           return u;
1412         }
1413       }
1414     }
1415   }
1416 
1417   return this;                     // No identity
1418 }
1419 
1420 //-----------------------------unique_input------------------------------------
1421 // Find the unique value, discounting top, self-loops, and casts.
1422 // Return top if there are no inputs, and self if there are multiple.
1423 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1424   //  1) One unique direct input,
1425   // or if uncast is true:
1426   //  2) some of the inputs have an intervening ConstraintCast
1427   //  3) an input is a self loop
1428   //
1429   //  1) input   or   2) input     or   3) input __
1430   //     /   \           /   \               \  /  \
1431   //     \   /          |    cast             phi  cast
1432   //      phi            \   /               /  \  /
1433   //                      phi               /    --
1434 
1435   Node* r = in(0);                      // RegionNode
1436   Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1437 
1438   for (uint i = 1, cnt = req(); i < cnt; ++i) {
1439     Node* rc = r->in(i);
1440     if (rc == NULL || phase->type(rc) == Type::TOP)
1441       continue;                 // ignore unreachable control path
1442     Node* n = in(i);
1443     if (n == NULL)
1444       continue;
1445     Node* un = n;
1446     if (uncast) {
1447 #ifdef ASSERT
1448       Node* m = un->uncast();
1449 #endif
1450       while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1451         Node* next = un->in(1);
1452         if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1453           // risk exposing raw ptr at safepoint
1454           break;
1455         }
1456         un = next;
1457       }
1458       assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1459     }
1460     if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1461       continue; // ignore if top, or in(i) and "this" are in a data cycle
1462     }
1463     // Check for a unique input (maybe uncasted)
1464     if (input == NULL) {
1465       input = un;
1466     } else if (input != un) {
1467       input = NodeSentinel; // no unique input
1468     }
1469   }
1470   if (input == NULL) {
1471     return phase->C->top();        // no inputs
1472   }
1473 
1474   if (input != NodeSentinel) {
1475     return input;           // one unique direct input
1476   }
1477 
1478   // Nothing.
1479   return NULL;
1480 }
1481 
1482 //------------------------------is_x2logic-------------------------------------
1483 // Check for simple convert-to-boolean pattern
1484 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1485 // Convert Phi to an ConvIB.
1486 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1487   assert(true_path !=0, "only diamond shape graph expected");
1488   // Convert the true/false index into an expected 0/1 return.
1489   // Map 2->0 and 1->1.
1490   int flipped = 2-true_path;
1491 
1492   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1493   // phi->region->if_proj->ifnode->bool->cmp
1494   Node *region = phi->in(0);
1495   Node *iff = region->in(1)->in(0);
1496   BoolNode *b = (BoolNode*)iff->in(1);
1497   const CmpNode *cmp = (CmpNode*)b->in(1);
1498 
1499   Node *zero = phi->in(1);
1500   Node *one  = phi->in(2);
1501   const Type *tzero = phase->type( zero );
1502   const Type *tone  = phase->type( one  );
1503 
1504   // Check for compare vs 0
1505   const Type *tcmp = phase->type(cmp->in(2));
1506   if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1507     // Allow cmp-vs-1 if the other input is bounded by 0-1
1508     if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1509       return NULL;
1510     flipped = 1-flipped;        // Test is vs 1 instead of 0!
1511   }
1512 
1513   // Check for setting zero/one opposite expected
1514   if( tzero == TypeInt::ZERO ) {
1515     if( tone == TypeInt::ONE ) {
1516     } else return NULL;
1517   } else if( tzero == TypeInt::ONE ) {
1518     if( tone == TypeInt::ZERO ) {
1519       flipped = 1-flipped;
1520     } else return NULL;
1521   } else return NULL;
1522 
1523   // Check for boolean test backwards
1524   if( b->_test._test == BoolTest::ne ) {
1525   } else if( b->_test._test == BoolTest::eq ) {
1526     flipped = 1-flipped;
1527   } else return NULL;
1528 
1529   // Build int->bool conversion
1530   Node *n = new Conv2BNode(cmp->in(1));
1531   if( flipped )
1532     n = new XorINode( phase->transform(n), phase->intcon(1) );
1533 
1534   return n;
1535 }
1536 
1537 //------------------------------is_cond_add------------------------------------
1538 // Check for simple conditional add pattern:  "(P < Q) ? X+Y : X;"
1539 // To be profitable the control flow has to disappear; there can be no other
1540 // values merging here.  We replace the test-and-branch with:
1541 // "(sgn(P-Q))&Y) + X".  Basically, convert "(P < Q)" into 0 or -1 by
1542 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1543 // Then convert Y to 0-or-Y and finally add.
1544 // This is a key transform for SpecJava _201_compress.
1545 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1546   assert(true_path !=0, "only diamond shape graph expected");
1547 
1548   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1549   // phi->region->if_proj->ifnode->bool->cmp
1550   RegionNode *region = (RegionNode*)phi->in(0);
1551   Node *iff = region->in(1)->in(0);
1552   BoolNode* b = iff->in(1)->as_Bool();
1553   const CmpNode *cmp = (CmpNode*)b->in(1);
1554 
1555   // Make sure only merging this one phi here
1556   if (region->has_unique_phi() != phi)  return NULL;
1557 
1558   // Make sure each arm of the diamond has exactly one output, which we assume
1559   // is the region.  Otherwise, the control flow won't disappear.
1560   if (region->in(1)->outcnt() != 1) return NULL;
1561   if (region->in(2)->outcnt() != 1) return NULL;
1562 
1563   // Check for "(P < Q)" of type signed int
1564   if (b->_test._test != BoolTest::lt)  return NULL;
1565   if (cmp->Opcode() != Op_CmpI)        return NULL;
1566 
1567   Node *p = cmp->in(1);
1568   Node *q = cmp->in(2);
1569   Node *n1 = phi->in(  true_path);
1570   Node *n2 = phi->in(3-true_path);
1571 
1572   int op = n1->Opcode();
1573   if( op != Op_AddI           // Need zero as additive identity
1574       /*&&op != Op_SubI &&
1575       op != Op_AddP &&
1576       op != Op_XorI &&
1577       op != Op_OrI*/ )
1578     return NULL;
1579 
1580   Node *x = n2;
1581   Node *y = NULL;
1582   if( x == n1->in(1) ) {
1583     y = n1->in(2);
1584   } else if( x == n1->in(2) ) {
1585     y = n1->in(1);
1586   } else return NULL;
1587 
1588   // Not so profitable if compare and add are constants
1589   if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1590     return NULL;
1591 
1592   Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1593   Node *j_and   = phase->transform( new AndINode(cmplt,y) );
1594   return new AddINode(j_and,x);
1595 }
1596 
1597 //------------------------------is_absolute------------------------------------
1598 // Check for absolute value.
1599 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1600   assert(true_path !=0, "only diamond shape graph expected");
1601 
1602   int  cmp_zero_idx = 0;        // Index of compare input where to look for zero
1603   int  phi_x_idx = 0;           // Index of phi input where to find naked x
1604 
1605   // ABS ends with the merge of 2 control flow paths.
1606   // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1607   int false_path = 3 - true_path;
1608 
1609   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1610   // phi->region->if_proj->ifnode->bool->cmp
1611   BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1612   Node *cmp = bol->in(1);
1613 
1614   // Check bool sense
1615   if (cmp->Opcode() == Op_CmpF || cmp->Opcode() == Op_CmpD) {
1616     switch (bol->_test._test) {
1617     case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path;  break;
1618     case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1619     case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path;  break;
1620     case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1621     default:           return NULL;                              break;
1622     }
1623   } else if (cmp->Opcode() == Op_CmpI || cmp->Opcode() == Op_CmpL) {
1624     switch (bol->_test._test) {
1625     case BoolTest::lt:
1626     case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1627     case BoolTest::gt:
1628     case BoolTest::ge: cmp_zero_idx = 2; phi_x_idx = true_path;  break;
1629     default:           return NULL;                              break;
1630     }
1631   }
1632 
1633   // Test is next
1634   const Type *tzero = NULL;
1635   switch (cmp->Opcode()) {
1636   case Op_CmpI:    tzero = TypeInt::ZERO; break;  // Integer ABS
1637   case Op_CmpL:    tzero = TypeLong::ZERO; break; // Long ABS
1638   case Op_CmpF:    tzero = TypeF::ZERO; break; // Float ABS
1639   case Op_CmpD:    tzero = TypeD::ZERO; break; // Double ABS
1640   default: return NULL;
1641   }
1642 
1643   // Find zero input of compare; the other input is being abs'd
1644   Node *x = NULL;
1645   bool flip = false;
1646   if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1647     x = cmp->in(3 - cmp_zero_idx);
1648   } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1649     // The test is inverted, we should invert the result...
1650     x = cmp->in(cmp_zero_idx);
1651     flip = true;
1652   } else {
1653     return NULL;
1654   }
1655 
1656   // Next get the 2 pieces being selected, one is the original value
1657   // and the other is the negated value.
1658   if( phi_root->in(phi_x_idx) != x ) return NULL;
1659 
1660   // Check other phi input for subtract node
1661   Node *sub = phi_root->in(3 - phi_x_idx);
1662 
1663   bool is_sub = sub->Opcode() == Op_SubF || sub->Opcode() == Op_SubD ||
1664                 sub->Opcode() == Op_SubI || sub->Opcode() == Op_SubL;
1665 
1666   // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1667   if (!is_sub || phase->type(sub->in(1)) != tzero || sub->in(2) != x) return NULL;
1668 
1669   if (tzero == TypeF::ZERO) {
1670     x = new AbsFNode(x);
1671     if (flip) {
1672       x = new SubFNode(sub->in(1), phase->transform(x));
1673     }
1674   } else if (tzero == TypeD::ZERO) {
1675     x = new AbsDNode(x);
1676     if (flip) {
1677       x = new SubDNode(sub->in(1), phase->transform(x));
1678     }
1679   } else if (tzero == TypeInt::ZERO && Matcher::match_rule_supported(Op_AbsI)) {
1680     x = new AbsINode(x);
1681     if (flip) {
1682       x = new SubINode(sub->in(1), phase->transform(x));
1683     }
1684   } else if (tzero == TypeLong::ZERO && Matcher::match_rule_supported(Op_AbsL)) {
1685     x = new AbsLNode(x);
1686     if (flip) {
1687       x = new SubLNode(sub->in(1), phase->transform(x));
1688     }
1689   } else return NULL;
1690 
1691   return x;
1692 }
1693 
1694 //------------------------------split_once-------------------------------------
1695 // Helper for split_flow_path
1696 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1697   igvn->hash_delete(n);         // Remove from hash before hacking edges
1698 
1699   uint j = 1;
1700   for (uint i = phi->req()-1; i > 0; i--) {
1701     if (phi->in(i) == val) {   // Found a path with val?
1702       // Add to NEW Region/Phi, no DU info
1703       newn->set_req( j++, n->in(i) );
1704       // Remove from OLD Region/Phi
1705       n->del_req(i);
1706     }
1707   }
1708 
1709   // Register the new node but do not transform it.  Cannot transform until the
1710   // entire Region/Phi conglomerate has been hacked as a single huge transform.
1711   igvn->register_new_node_with_optimizer( newn );
1712 
1713   // Now I can point to the new node.
1714   n->add_req(newn);
1715   igvn->_worklist.push(n);
1716 }
1717 
1718 //------------------------------split_flow_path--------------------------------
1719 // Check for merging identical values and split flow paths
1720 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1721   BasicType bt = phi->type()->basic_type();
1722   if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1723     return NULL;                // Bail out on funny non-value stuff
1724   if( phi->req() <= 3 )         // Need at least 2 matched inputs and a
1725     return NULL;                // third unequal input to be worth doing
1726 
1727   // Scan for a constant
1728   uint i;
1729   for( i = 1; i < phi->req()-1; i++ ) {
1730     Node *n = phi->in(i);
1731     if( !n ) return NULL;
1732     if( phase->type(n) == Type::TOP ) return NULL;
1733     if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1734       break;
1735   }
1736   if( i >= phi->req() )         // Only split for constants
1737     return NULL;
1738 
1739   Node *val = phi->in(i);       // Constant to split for
1740   uint hit = 0;                 // Number of times it occurs
1741   Node *r = phi->region();
1742 
1743   for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1744     Node *n = phi->in(i);
1745     if( !n ) return NULL;
1746     if( phase->type(n) == Type::TOP ) return NULL;
1747     if( phi->in(i) == val ) {
1748       hit++;
1749       if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1750         return NULL;            // don't split loop entry path
1751       }
1752     }
1753   }
1754 
1755   if( hit <= 1 ||               // Make sure we find 2 or more
1756       hit == phi->req()-1 )     // and not ALL the same value
1757     return NULL;
1758 
1759   // Now start splitting out the flow paths that merge the same value.
1760   // Split first the RegionNode.
1761   PhaseIterGVN *igvn = phase->is_IterGVN();
1762   RegionNode *newr = new RegionNode(hit+1);
1763   split_once(igvn, phi, val, r, newr);
1764 
1765   // Now split all other Phis than this one
1766   for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1767     Node* phi2 = r->fast_out(k);
1768     if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1769       PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1770       split_once(igvn, phi, val, phi2, newphi);
1771     }
1772   }
1773 
1774   // Clean up this guy
1775   igvn->hash_delete(phi);
1776   for( i = phi->req()-1; i > 0; i-- ) {
1777     if( phi->in(i) == val ) {
1778       phi->del_req(i);
1779     }
1780   }
1781   phi->add_req(val);
1782 
1783   return phi;
1784 }
1785 
1786 //=============================================================================
1787 //------------------------------simple_data_loop_check-------------------------
1788 //  Try to determining if the phi node in a simple safe/unsafe data loop.
1789 //  Returns:
1790 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1791 // Safe       - safe case when the phi and it's inputs reference only safe data
1792 //              nodes;
1793 // Unsafe     - the phi and it's inputs reference unsafe data nodes but there
1794 //              is no reference back to the phi - need a graph walk
1795 //              to determine if it is in a loop;
1796 // UnsafeLoop - unsafe case when the phi references itself directly or through
1797 //              unsafe data node.
1798 //  Note: a safe data node is a node which could/never reference itself during
1799 //  GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1800 //  I mark Phi nodes as safe node not only because they can reference itself
1801 //  but also to prevent mistaking the fallthrough case inside an outer loop
1802 //  as dead loop when the phi references itselfs through an other phi.
1803 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1804   // It is unsafe loop if the phi node references itself directly.
1805   if (in == (Node*)this)
1806     return UnsafeLoop; // Unsafe loop
1807   // Unsafe loop if the phi node references itself through an unsafe data node.
1808   // Exclude cases with null inputs or data nodes which could reference
1809   // itself (safe for dead loops).
1810   if (in != NULL && !in->is_dead_loop_safe()) {
1811     // Check inputs of phi's inputs also.
1812     // It is much less expensive then full graph walk.
1813     uint cnt = in->req();
1814     uint i = (in->is_Proj() && !in->is_CFG())  ? 0 : 1;
1815     for (; i < cnt; ++i) {
1816       Node* m = in->in(i);
1817       if (m == (Node*)this)
1818         return UnsafeLoop; // Unsafe loop
1819       if (m != NULL && !m->is_dead_loop_safe()) {
1820         // Check the most common case (about 30% of all cases):
1821         // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1822         Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1823         if (m1 == (Node*)this)
1824           return UnsafeLoop; // Unsafe loop
1825         if (m1 != NULL && m1 == m->in(2) &&
1826             m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1827           continue; // Safe case
1828         }
1829         // The phi references an unsafe node - need full analysis.
1830         return Unsafe;
1831       }
1832     }
1833   }
1834   return Safe; // Safe case - we can optimize the phi node.
1835 }
1836 
1837 //------------------------------is_unsafe_data_reference-----------------------
1838 // If phi can be reached through the data input - it is data loop.
1839 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1840   assert(req() > 1, "");
1841   // First, check simple cases when phi references itself directly or
1842   // through an other node.
1843   LoopSafety safety = simple_data_loop_check(in);
1844   if (safety == UnsafeLoop)
1845     return true;  // phi references itself - unsafe loop
1846   else if (safety == Safe)
1847     return false; // Safe case - phi could be replaced with the unique input.
1848 
1849   // Unsafe case when we should go through data graph to determine
1850   // if the phi references itself.
1851 
1852   ResourceMark rm;
1853 
1854   Node_List nstack;
1855   VectorSet visited;
1856 
1857   nstack.push(in); // Start with unique input.
1858   visited.set(in->_idx);
1859   while (nstack.size() != 0) {
1860     Node* n = nstack.pop();
1861     uint cnt = n->req();
1862     uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1863     for (; i < cnt; i++) {
1864       Node* m = n->in(i);
1865       if (m == (Node*)this) {
1866         return true;    // Data loop
1867       }
1868       if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1869         if (!visited.test_set(m->_idx))
1870           nstack.push(m);
1871       }
1872     }
1873   }
1874   return false; // The phi is not reachable from its inputs
1875 }
1876 
1877 // Is this Phi's region or some inputs to the region enqueued for IGVN
1878 // and so could cause the region to be optimized out?
1879 bool PhiNode::wait_for_region_igvn(PhaseGVN* phase) {
1880   PhaseIterGVN* igvn = phase->is_IterGVN();
1881   Unique_Node_List& worklist = igvn->_worklist;
1882   bool delay = false;
1883   Node* r = in(0);
1884   for (uint j = 1; j < req(); j++) {
1885     Node* rc = r->in(j);
1886     Node* n = in(j);
1887     if (rc != NULL &&
1888         rc->is_Proj()) {
1889       if (worklist.member(rc)) {
1890         delay = true;
1891       } else if (rc->in(0) != NULL &&
1892                  rc->in(0)->is_If()) {
1893         if (worklist.member(rc->in(0))) {
1894           delay = true;
1895         } else if (rc->in(0)->in(1) != NULL &&
1896                    rc->in(0)->in(1)->is_Bool()) {
1897           if (worklist.member(rc->in(0)->in(1))) {
1898             delay = true;
1899           } else if (rc->in(0)->in(1)->in(1) != NULL &&
1900                      rc->in(0)->in(1)->in(1)->is_Cmp()) {
1901             if (worklist.member(rc->in(0)->in(1)->in(1))) {
1902               delay = true;
1903             }
1904           }
1905         }
1906       }
1907     }
1908   }
1909   if (delay) {
1910     worklist.push(this);
1911   }
1912   return delay;
1913 }
1914 
1915 // Push inline type input nodes (and null) down through the phi recursively (can handle data loops).
1916 InlineTypeBaseNode* PhiNode::push_inline_types_through(PhaseGVN* phase, bool can_reshape, ciInlineKlass* vk, bool is_init) {
1917   InlineTypeBaseNode* vt = NULL;
1918   if (_type->isa_ptr()) {
1919     vt = InlineTypePtrNode::make_null(*phase, vk)->clone_with_phis(phase, in(0), is_init);
1920   } else {
1921     vt = InlineTypeNode::make_null(*phase, vk)->clone_with_phis(phase, in(0), is_init);
1922   }
1923   if (can_reshape) {
1924     // Replace phi right away to be able to use the inline
1925     // type node when reaching the phi again through data loops.
1926     PhaseIterGVN* igvn = phase->is_IterGVN();
1927     for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
1928       Node* u = fast_out(i);
1929       igvn->rehash_node_delayed(u);
1930       imax -= u->replace_edge(this, vt);
1931       --i;
1932     }
1933     assert(outcnt() == 0, "should be dead now");
1934   }
1935   ResourceMark rm;
1936   Node_List casts;
1937   for (uint i = 1; i < req(); ++i) {
1938     Node* n = in(i);
1939     while (n->is_ConstraintCast()) {
1940       casts.push(n);
1941       n = n->in(1);
1942     }
1943     if (phase->type(n)->is_zero_type()) {
1944       n = InlineTypePtrNode::make_null(*phase, vk);
1945     } else if (n->is_Phi()) {
1946       assert(can_reshape, "can only handle phis during IGVN");
1947       n = phase->transform(n->as_Phi()->push_inline_types_through(phase, can_reshape, vk, is_init));
1948     }
1949     while (casts.size() != 0) {
1950       // Update the cast input and let ConstraintCastNode::Ideal push it through the InlineTypePtrNode
1951       Node* cast = casts.pop();
1952       phase->hash_delete(cast);
1953       cast->set_req(1, n);
1954       n = phase->transform(cast);
1955       assert(n->is_InlineTypePtr(), "Failed to push cast through InlineTypePtr");
1956     }
1957     bool transform = !can_reshape && (i == (req()-1)); // Transform phis on last merge
1958     vt->merge_with(phase, n->as_InlineTypeBase(), i, transform);
1959   }
1960   return vt;
1961 }
1962 
1963 //------------------------------Ideal------------------------------------------
1964 // Return a node which is more "ideal" than the current node.  Must preserve
1965 // the CFG, but we can still strip out dead paths.
1966 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1967   Node *r = in(0);              // RegionNode
1968   assert(r != NULL && r->is_Region(), "this phi must have a region");
1969   assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1970 
1971   // Note: During parsing, phis are often transformed before their regions.
1972   // This means we have to use type_or_null to defend against untyped regions.
1973   if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1974     return NULL;                // No change
1975 
1976   Node *top = phase->C->top();
1977   bool new_phi = (outcnt() == 0); // transforming new Phi
1978   // No change for igvn if new phi is not hooked
1979   if (new_phi && can_reshape)
1980     return NULL;
1981 
1982   // The are 2 situations when only one valid phi's input is left
1983   // (in addition to Region input).
1984   // One: region is not loop - replace phi with this input.
1985   // Two: region is loop - replace phi with top since this data path is dead
1986   //                       and we need to break the dead data loop.
1987   Node* progress = NULL;        // Record if any progress made
1988   for( uint j = 1; j < req(); ++j ){ // For all paths in
1989     // Check unreachable control paths
1990     Node* rc = r->in(j);
1991     Node* n = in(j);            // Get the input
1992     if (rc == NULL || phase->type(rc) == Type::TOP) {
1993       if (n != top) {           // Not already top?
1994         PhaseIterGVN *igvn = phase->is_IterGVN();
1995         if (can_reshape && igvn != NULL) {
1996           igvn->_worklist.push(r);
1997         }
1998         // Nuke it down
1999         set_req_X(j, top, phase);
2000         progress = this;        // Record progress
2001       }
2002     }
2003   }
2004 
2005   if (can_reshape && outcnt() == 0) {
2006     // set_req() above may kill outputs if Phi is referenced
2007     // only by itself on the dead (top) control path.
2008     return top;
2009   }
2010 
2011   bool uncasted = false;
2012   Node* uin = unique_input(phase, false);
2013   if (uin == NULL && can_reshape &&
2014       // If there is a chance that the region can be optimized out do
2015       // not add a cast node that we can't remove yet.
2016       !wait_for_region_igvn(phase)) {
2017     uncasted = true;
2018     uin = unique_input(phase, true);
2019   }
2020   if (uin == top) {             // Simplest case: no alive inputs.
2021     if (can_reshape)            // IGVN transformation
2022       return top;
2023     else
2024       return NULL;              // Identity will return TOP
2025   } else if (uin != NULL) {
2026     // Only one not-NULL unique input path is left.
2027     // Determine if this input is backedge of a loop.
2028     // (Skip new phis which have no uses and dead regions).
2029     if (outcnt() > 0 && r->in(0) != NULL) {
2030       if (is_data_loop(r->as_Region(), uin, phase)) {
2031         // Break this data loop to avoid creation of a dead loop.
2032         if (can_reshape) {
2033           return top;
2034         } else {
2035           // We can't return top if we are in Parse phase - cut inputs only
2036           // let Identity to handle the case.
2037           replace_edge(uin, top, phase);
2038           return NULL;
2039         }
2040       }
2041     }
2042 
2043     if (uncasted) {
2044       // Add cast nodes between the phi to be removed and its unique input.
2045       // Wait until after parsing for the type information to propagate from the casts.
2046       assert(can_reshape, "Invalid during parsing");
2047       const Type* phi_type = bottom_type();
2048       // Add casts to carry the control dependency of the Phi that is
2049       // going away
2050       Node* cast = NULL;
2051       if (phi_type->isa_ptr()) {
2052         const Type* uin_type = phase->type(uin);
2053         if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
2054           cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, ConstraintCastNode::StrongDependency);
2055         } else {
2056           // Use a CastPP for a cast to not null and a CheckCastPP for
2057           // a cast to a new klass (and both if both null-ness and
2058           // klass change).
2059 
2060           // If the type of phi is not null but the type of uin may be
2061           // null, uin's type must be casted to not null
2062           if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
2063               uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
2064             cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, ConstraintCastNode::StrongDependency);
2065           }
2066 
2067           // If the type of phi and uin, both casted to not null,
2068           // differ the klass of uin must be (check)cast'ed to match
2069           // that of phi
2070           if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
2071             Node* n = uin;
2072             if (cast != NULL) {
2073               cast = phase->transform(cast);
2074               n = cast;
2075             }
2076             cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, ConstraintCastNode::StrongDependency);
2077           }
2078           if (cast == NULL) {
2079             cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, ConstraintCastNode::StrongDependency);
2080           }
2081         }
2082       } else {
2083         cast = ConstraintCastNode::make_cast_for_type(r, uin, phi_type, ConstraintCastNode::StrongDependency);
2084       }
2085       assert(cast != NULL, "cast should be set");
2086       cast = phase->transform(cast);
2087       // set all inputs to the new cast(s) so the Phi is removed by Identity
2088       PhaseIterGVN* igvn = phase->is_IterGVN();
2089       for (uint i = 1; i < req(); i++) {
2090         set_req_X(i, cast, igvn);
2091       }
2092       uin = cast;
2093     }
2094 
2095     // One unique input.
2096     debug_only(Node* ident = Identity(phase));
2097     // The unique input must eventually be detected by the Identity call.
2098 #ifdef ASSERT
2099     if (ident != uin && !ident->is_top()) {
2100       // print this output before failing assert
2101       r->dump(3);
2102       this->dump(3);
2103       ident->dump();
2104       uin->dump();
2105     }
2106 #endif
2107     assert(ident == uin || ident->is_top(), "Identity must clean this up");
2108     return NULL;
2109   }
2110 
2111   Node* opt = NULL;
2112   int true_path = is_diamond_phi();
2113   if (true_path != 0 &&
2114       // If one of the diamond's branch is in the process of dying then, the Phi's input for that branch might transform
2115       // to top. If that happens replacing the Phi with an operation that consumes the Phi's inputs will cause the Phi
2116       // to be replaced by top. To prevent that, delay the transformation until the branch has a chance to be removed.
2117       !(can_reshape && wait_for_region_igvn(phase))) {
2118     // Check for CMove'ing identity. If it would be unsafe,
2119     // handle it here. In the safe case, let Identity handle it.
2120     Node* unsafe_id = is_cmove_id(phase, true_path);
2121     if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
2122       opt = unsafe_id;
2123 
2124     // Check for simple convert-to-boolean pattern
2125     if( opt == NULL )
2126       opt = is_x2logic(phase, this, true_path);
2127 
2128     // Check for absolute value
2129     if( opt == NULL )
2130       opt = is_absolute(phase, this, true_path);
2131 
2132     // Check for conditional add
2133     if( opt == NULL && can_reshape )
2134       opt = is_cond_add(phase, this, true_path);
2135 
2136     // These 4 optimizations could subsume the phi:
2137     // have to check for a dead data loop creation.
2138     if( opt != NULL ) {
2139       if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
2140         // Found dead loop.
2141         if( can_reshape )
2142           return top;
2143         // We can't return top if we are in Parse phase - cut inputs only
2144         // to stop further optimizations for this phi. Identity will return TOP.
2145         assert(req() == 3, "only diamond merge phi here");
2146         set_req(1, top);
2147         set_req(2, top);
2148         return NULL;
2149       } else {
2150         return opt;
2151       }
2152     }
2153   }
2154 
2155   // Check for merging identical values and split flow paths
2156   if (can_reshape) {
2157     opt = split_flow_path(phase, this);
2158     // This optimization only modifies phi - don't need to check for dead loop.
2159     assert(opt == NULL || opt == this, "do not elide phi");
2160     if (opt != NULL)  return opt;
2161   }
2162 
2163   if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
2164     // Try to undo Phi of AddP:
2165     // (Phi (AddP base address offset) (AddP base2 address2 offset2))
2166     // becomes:
2167     // newbase := (Phi base base2)
2168     // newaddress := (Phi address address2)
2169     // newoffset := (Phi offset offset2)
2170     // (AddP newbase newaddress newoffset)
2171     //
2172     // This occurs as a result of unsuccessful split_thru_phi and
2173     // interferes with taking advantage of addressing modes. See the
2174     // clone_shift_expressions code in matcher.cpp
2175     Node* addp = in(1);
2176     Node* base = addp->in(AddPNode::Base);
2177     Node* address = addp->in(AddPNode::Address);
2178     Node* offset = addp->in(AddPNode::Offset);
2179     if (base != NULL && address != NULL && offset != NULL &&
2180         !base->is_top() && !address->is_top() && !offset->is_top()) {
2181       const Type* base_type = base->bottom_type();
2182       const Type* address_type = address->bottom_type();
2183       // make sure that all the inputs are similar to the first one,
2184       // i.e. AddP with base == address and same offset as first AddP
2185       bool doit = true;
2186       for (uint i = 2; i < req(); i++) {
2187         if (in(i) == NULL ||
2188             in(i)->Opcode() != Op_AddP ||
2189             in(i)->in(AddPNode::Base) == NULL ||
2190             in(i)->in(AddPNode::Address) == NULL ||
2191             in(i)->in(AddPNode::Offset) == NULL ||
2192             in(i)->in(AddPNode::Base)->is_top() ||
2193             in(i)->in(AddPNode::Address)->is_top() ||
2194             in(i)->in(AddPNode::Offset)->is_top()) {
2195           doit = false;
2196           break;
2197         }
2198         if (in(i)->in(AddPNode::Offset) != base) {
2199           base = NULL;
2200         }
2201         if (in(i)->in(AddPNode::Offset) != offset) {
2202           offset = NULL;
2203         }
2204         if (in(i)->in(AddPNode::Address) != address) {
2205           address = NULL;
2206         }
2207         // Accumulate type for resulting Phi
2208         base_type = base_type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
2209         address_type = address_type->meet_speculative(in(i)->in(AddPNode::Address)->bottom_type());
2210       }
2211       if (doit && base == NULL) {
2212         // Check for neighboring AddP nodes in a tree.
2213         // If they have a base, use that it.
2214         for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
2215           Node* u = this->fast_out(k);
2216           if (u->is_AddP()) {
2217             Node* base2 = u->in(AddPNode::Base);
2218             if (base2 != NULL && !base2->is_top()) {
2219               if (base == NULL)
2220                 base = base2;
2221               else if (base != base2)
2222                 { doit = false; break; }
2223             }
2224           }
2225         }
2226       }
2227       if (doit) {
2228         if (base == NULL) {
2229           base = new PhiNode(in(0), base_type, NULL);
2230           for (uint i = 1; i < req(); i++) {
2231             base->init_req(i, in(i)->in(AddPNode::Base));
2232           }
2233           phase->is_IterGVN()->register_new_node_with_optimizer(base);
2234         }
2235         if (address == NULL) {
2236           address = new PhiNode(in(0), address_type, NULL);
2237           for (uint i = 1; i < req(); i++) {
2238             address->init_req(i, in(i)->in(AddPNode::Address));
2239           }
2240           phase->is_IterGVN()->register_new_node_with_optimizer(address);
2241         }
2242         if (offset == NULL) {
2243           offset = new PhiNode(in(0), TypeX_X, NULL);
2244           for (uint i = 1; i < req(); i++) {
2245             offset->init_req(i, in(i)->in(AddPNode::Offset));
2246           }
2247           phase->is_IterGVN()->register_new_node_with_optimizer(offset);
2248         }
2249         return new AddPNode(base, address, offset);
2250       }
2251     }
2252   }
2253 
2254   // Split phis through memory merges, so that the memory merges will go away.
2255   // Piggy-back this transformation on the search for a unique input....
2256   // It will be as if the merged memory is the unique value of the phi.
2257   // (Do not attempt this optimization unless parsing is complete.
2258   // It would make the parser's memory-merge logic sick.)
2259   // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2260   if (progress == NULL && can_reshape && type() == Type::MEMORY) {
2261     // see if this phi should be sliced
2262     uint merge_width = 0;
2263     bool saw_self = false;
2264     // TODO revisit this with JDK-8247216
2265     bool mergemem_only = true;
2266     for( uint i=1; i<req(); ++i ) {// For all paths in
2267       Node *ii = in(i);
2268       // TOP inputs should not be counted as safe inputs because if the
2269       // Phi references itself through all other inputs then splitting the
2270       // Phi through memory merges would create dead loop at later stage.
2271       if (ii == top) {
2272         return NULL; // Delay optimization until graph is cleaned.
2273       }
2274       if (ii->is_MergeMem()) {
2275         MergeMemNode* n = ii->as_MergeMem();
2276         merge_width = MAX2(merge_width, n->req());
2277         saw_self = saw_self || (n->base_memory() == this);
2278       } else {
2279         mergemem_only = false;
2280       }
2281     }
2282 
2283     // This restriction is temporarily necessary to ensure termination:
2284     if (!mergemem_only && !saw_self && adr_type() == TypePtr::BOTTOM)  merge_width = 0;
2285 
2286     if (merge_width > Compile::AliasIdxRaw) {
2287       // found at least one non-empty MergeMem
2288       const TypePtr* at = adr_type();
2289       if (at != TypePtr::BOTTOM) {
2290         // Patch the existing phi to select an input from the merge:
2291         // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2292         //     Phi:AT1(...m1...)
2293         int alias_idx = phase->C->get_alias_index(at);
2294         for (uint i=1; i<req(); ++i) {
2295           Node *ii = in(i);
2296           if (ii->is_MergeMem()) {
2297             MergeMemNode* n = ii->as_MergeMem();
2298             // compress paths and change unreachable cycles to TOP
2299             // If not, we can update the input infinitely along a MergeMem cycle
2300             // Equivalent code is in MemNode::Ideal_common
2301             Node *m  = phase->transform(n);
2302             if (outcnt() == 0) {  // Above transform() may kill us!
2303               return top;
2304             }
2305             // If transformed to a MergeMem, get the desired slice
2306             // Otherwise the returned node represents memory for every slice
2307             Node *new_mem = (m->is_MergeMem()) ?
2308                              m->as_MergeMem()->memory_at(alias_idx) : m;
2309             // Update input if it is progress over what we have now
2310             if (new_mem != ii) {
2311               set_req_X(i, new_mem, phase->is_IterGVN());
2312               progress = this;
2313             }
2314           }
2315         }
2316       } else {
2317         // We know that at least one MergeMem->base_memory() == this
2318         // (saw_self == true). If all other inputs also references this phi
2319         // (directly or through data nodes) - it is a dead loop.
2320         bool saw_safe_input = false;
2321         for (uint j = 1; j < req(); ++j) {
2322           Node* n = in(j);
2323           if (n->is_MergeMem()) {
2324             MergeMemNode* mm = n->as_MergeMem();
2325             if (mm->base_memory() == this || mm->base_memory() == mm->empty_memory()) {
2326               // Skip this input if it references back to this phi or if the memory path is dead
2327               continue;
2328             }
2329           }
2330           if (!is_unsafe_data_reference(n)) {
2331             saw_safe_input = true; // found safe input
2332             break;
2333           }
2334         }
2335         if (!saw_safe_input) {
2336           // There is a dead loop: All inputs are either dead or reference back to this phi
2337           return top;
2338         }
2339 
2340         // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2341         //     MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2342         PhaseIterGVN* igvn = phase->is_IterGVN();
2343         Node* hook = new Node(1);
2344         PhiNode* new_base = (PhiNode*) clone();
2345         // Must eagerly register phis, since they participate in loops.
2346         if (igvn) {
2347           igvn->register_new_node_with_optimizer(new_base);
2348           hook->add_req(new_base);
2349         }
2350         MergeMemNode* result = MergeMemNode::make(new_base);
2351         for (uint i = 1; i < req(); ++i) {
2352           Node *ii = in(i);
2353           if (ii->is_MergeMem()) {
2354             MergeMemNode* n = ii->as_MergeMem();
2355             if (igvn) {
2356               // TODO revisit this with JDK-8247216
2357               // Put 'n' on the worklist because it might be modified by MergeMemStream::iteration_setup
2358               igvn->_worklist.push(n);
2359             }
2360             for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2361               // If we have not seen this slice yet, make a phi for it.
2362               bool made_new_phi = false;
2363               if (mms.is_empty()) {
2364                 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2365                 made_new_phi = true;
2366                 if (igvn) {
2367                   igvn->register_new_node_with_optimizer(new_phi);
2368                   hook->add_req(new_phi);
2369                 }
2370                 mms.set_memory(new_phi);
2371               }
2372               Node* phi = mms.memory();
2373               assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2374               phi->set_req(i, mms.memory2());
2375             }
2376           }
2377         }
2378         // Distribute all self-loops.
2379         { // (Extra braces to hide mms.)
2380           for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2381             Node* phi = mms.memory();
2382             for (uint i = 1; i < req(); ++i) {
2383               if (phi->in(i) == this)  phi->set_req(i, phi);
2384             }
2385           }
2386         }
2387         // now transform the new nodes, and return the mergemem
2388         for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2389           Node* phi = mms.memory();
2390           mms.set_memory(phase->transform(phi));
2391         }
2392         hook->destruct(igvn);
2393         // Replace self with the result.
2394         return result;
2395       }
2396     }
2397     //
2398     // Other optimizations on the memory chain
2399     //
2400     const TypePtr* at = adr_type();
2401     for( uint i=1; i<req(); ++i ) {// For all paths in
2402       Node *ii = in(i);
2403       Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2404       if (ii != new_in ) {
2405         set_req(i, new_in);
2406         progress = this;
2407       }
2408     }
2409   }
2410 
2411 #ifdef _LP64
2412   // Push DecodeN/DecodeNKlass down through phi.
2413   // The rest of phi graph will transform by split EncodeP node though phis up.
2414   if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2415     bool may_push = true;
2416     bool has_decodeN = false;
2417     bool is_decodeN = false;
2418     for (uint i=1; i<req(); ++i) {// For all paths in
2419       Node *ii = in(i);
2420       if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2421         // Do optimization if a non dead path exist.
2422         if (ii->in(1)->bottom_type() != Type::TOP) {
2423           has_decodeN = true;
2424           is_decodeN = ii->is_DecodeN();
2425         }
2426       } else if (!ii->is_Phi()) {
2427         may_push = false;
2428       }
2429     }
2430 
2431     if (has_decodeN && may_push) {
2432       PhaseIterGVN *igvn = phase->is_IterGVN();
2433       // Make narrow type for new phi.
2434       const Type* narrow_t;
2435       if (is_decodeN) {
2436         narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2437       } else {
2438         narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2439       }
2440       PhiNode* new_phi = new PhiNode(r, narrow_t);
2441       uint orig_cnt = req();
2442       for (uint i=1; i<req(); ++i) {// For all paths in
2443         Node *ii = in(i);
2444         Node* new_ii = NULL;
2445         if (ii->is_DecodeNarrowPtr()) {
2446           assert(ii->bottom_type() == bottom_type(), "sanity");
2447           new_ii = ii->in(1);
2448         } else {
2449           assert(ii->is_Phi(), "sanity");
2450           if (ii->as_Phi() == this) {
2451             new_ii = new_phi;
2452           } else {
2453             if (is_decodeN) {
2454               new_ii = new EncodePNode(ii, narrow_t);
2455             } else {
2456               new_ii = new EncodePKlassNode(ii, narrow_t);
2457             }
2458             igvn->register_new_node_with_optimizer(new_ii);
2459           }
2460         }
2461         new_phi->set_req(i, new_ii);
2462       }
2463       igvn->register_new_node_with_optimizer(new_phi, this);
2464       if (is_decodeN) {
2465         progress = new DecodeNNode(new_phi, bottom_type());
2466       } else {
2467         progress = new DecodeNKlassNode(new_phi, bottom_type());
2468       }
2469     }
2470   }
2471 #endif
2472 
2473   // Phi (VB ... VB) => VB (Phi ...) (Phi ...)
2474   if (EnableVectorReboxing && can_reshape && progress == NULL) {
2475     PhaseIterGVN* igvn = phase->is_IterGVN();
2476 
2477     bool all_inputs_are_equiv_vboxes = true;
2478     for (uint i = 1; i < req(); ++i) {
2479       Node* n = in(i);
2480       if (in(i)->Opcode() != Op_VectorBox) {
2481         all_inputs_are_equiv_vboxes = false;
2482         break;
2483       }
2484       // Check that vector type of vboxes is equivalent
2485       if (i != 1) {
2486         if (Type::cmp(in(i-0)->in(VectorBoxNode::Value)->bottom_type(),
2487                       in(i-1)->in(VectorBoxNode::Value)->bottom_type()) != 0) {
2488           all_inputs_are_equiv_vboxes = false;
2489           break;
2490         }
2491         if (Type::cmp(in(i-0)->in(VectorBoxNode::Box)->bottom_type(),
2492                       in(i-1)->in(VectorBoxNode::Box)->bottom_type()) != 0) {
2493           all_inputs_are_equiv_vboxes = false;
2494           break;
2495         }
2496       }
2497     }
2498 
2499     if (all_inputs_are_equiv_vboxes) {
2500       VectorBoxNode* vbox = static_cast<VectorBoxNode*>(in(1));
2501       PhiNode* new_vbox_phi = new PhiNode(r, vbox->box_type());
2502       PhiNode* new_vect_phi = new PhiNode(r, vbox->vec_type());
2503       for (uint i = 1; i < req(); ++i) {
2504         VectorBoxNode* old_vbox = static_cast<VectorBoxNode*>(in(i));
2505         new_vbox_phi->set_req(i, old_vbox->in(VectorBoxNode::Box));
2506         new_vect_phi->set_req(i, old_vbox->in(VectorBoxNode::Value));
2507       }
2508       igvn->register_new_node_with_optimizer(new_vbox_phi, this);
2509       igvn->register_new_node_with_optimizer(new_vect_phi, this);
2510       progress = new VectorBoxNode(igvn->C, new_vbox_phi, new_vect_phi, vbox->box_type(), vbox->vec_type());
2511     }
2512   }
2513 
2514   // Check recursively if inputs are either an inline type, constant null
2515   // or another Phi (including self references through data loops). If so,
2516   // push the inline types down through the phis to enable folding of loads.
2517   if (EnableValhalla && (_type->isa_ptr() || _type->isa_inlinetype()) && req() > 2 && progress == NULL) {
2518     ResourceMark rm;
2519     Unique_Node_List worklist;
2520     worklist.push(this);
2521     bool can_optimize = true;
2522     ciInlineKlass* vk = NULL;
2523     // true if all IsInit inputs of all InlineType* nodes are true
2524     bool is_init = true;
2525     Node_List casts;
2526 
2527     for (uint next = 0; next < worklist.size() && can_optimize; next++) {
2528       Node* phi = worklist.at(next);
2529       for (uint i = 1; i < phi->req() && can_optimize; i++) {
2530         Node* n = phi->in(i);
2531         if (n == NULL) {
2532           can_optimize = false;
2533           break;
2534         }
2535         while (n->is_ConstraintCast()) {
2536           casts.push(n);
2537           n = n->in(1);
2538         }
2539         const Type* t = phase->type(n);
2540         if (n->is_InlineTypeBase() && n->as_InlineTypeBase()->can_merge() &&
2541             (vk == NULL || vk == t->inline_klass())) {
2542           vk = (vk == NULL) ? t->inline_klass() : vk;
2543           if (phase->find_int_con(n->as_InlineTypeBase()->get_is_init(), 0) != 1) {
2544             is_init = false;
2545           }
2546         } else if (n->is_Phi() && can_reshape && (n->bottom_type()->isa_ptr() || n->bottom_type()->isa_inlinetype())) {
2547           worklist.push(n);
2548         } else if (t->is_zero_type()) {
2549           is_init = false;
2550         } else {
2551           can_optimize = false;
2552         }
2553       }
2554     }
2555     // Check if cast nodes can be pushed through
2556     const Type* t = Type::get_const_type(vk);
2557     while (casts.size() != 0 && can_optimize && t != NULL) {
2558       Node* cast = casts.pop();
2559       if (t->filter(cast->bottom_type()) == Type::TOP) {
2560         can_optimize = false;
2561       }
2562     }
2563     if (can_optimize && vk != NULL) {
2564 // TODO 8275400
2565 //      assert(!_type->isa_ptr() || _type->maybe_null() || is_init, "Phi not null but a possible null was seen");
2566       progress = push_inline_types_through(phase, can_reshape, vk, is_init);
2567     }
2568   }
2569 
2570   return progress;              // Return any progress
2571 }
2572 
2573 bool PhiNode::is_data_loop(RegionNode* r, Node* uin, const PhaseGVN* phase) {
2574   // First, take the short cut when we know it is a loop and the EntryControl data path is dead.
2575   // The loop node may only have one input because the entry path was removed in PhaseIdealLoop::Dominators().
2576   // Then, check if there is a data loop when the phi references itself directly or through other data nodes.
2577   assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
2578   const bool is_loop = (r->is_Loop() && r->req() == 3);
2579   const Node* top = phase->C->top();
2580   if (is_loop) {
2581     return !uin->eqv_uncast(in(LoopNode::EntryControl));
2582   } else {
2583     // We have a data loop either with an unsafe data reference or if a region is unreachable.
2584     return is_unsafe_data_reference(uin)
2585            || (r->req() == 3 && (r->in(1) != top && r->in(2) == top && r->is_unreachable_region(phase)));
2586   }
2587 }
2588 
2589 //------------------------------is_tripcount-----------------------------------
2590 bool PhiNode::is_tripcount(BasicType bt) const {
2591   return (in(0) != NULL && in(0)->is_BaseCountedLoop() &&
2592           in(0)->as_BaseCountedLoop()->operates_on(bt, true) &&
2593           in(0)->as_BaseCountedLoop()->phi() == this);
2594 }
2595 
2596 //------------------------------out_RegMask------------------------------------
2597 const RegMask &PhiNode::in_RegMask(uint i) const {
2598   return i ? out_RegMask() : RegMask::Empty;
2599 }
2600 
2601 const RegMask &PhiNode::out_RegMask() const {
2602   uint ideal_reg = _type->ideal_reg();
2603   assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2604   if( ideal_reg == 0 ) return RegMask::Empty;
2605   assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2606   return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2607 }
2608 
2609 #ifndef PRODUCT
2610 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2611   // For a PhiNode, the set of related nodes includes all inputs till level 2,
2612   // and all outputs till level 1. In compact mode, inputs till level 1 are
2613   // collected.
2614   this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2615   this->collect_nodes(out_rel, -1, false, false);
2616 }
2617 
2618 void PhiNode::dump_spec(outputStream *st) const {
2619   TypeNode::dump_spec(st);
2620   if (is_tripcount(T_INT) || is_tripcount(T_LONG)) {
2621     st->print(" #tripcount");
2622   }
2623 }
2624 #endif
2625 
2626 
2627 //=============================================================================
2628 const Type* GotoNode::Value(PhaseGVN* phase) const {
2629   // If the input is reachable, then we are executed.
2630   // If the input is not reachable, then we are not executed.
2631   return phase->type(in(0));
2632 }
2633 
2634 Node* GotoNode::Identity(PhaseGVN* phase) {
2635   return in(0);                // Simple copy of incoming control
2636 }
2637 
2638 const RegMask &GotoNode::out_RegMask() const {
2639   return RegMask::Empty;
2640 }
2641 
2642 #ifndef PRODUCT
2643 //-----------------------------related-----------------------------------------
2644 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2645 // outputs at level 1. This is regardless of compact mode.
2646 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2647   this->collect_nodes(in_rel, 1, false, false);
2648   this->collect_nodes(out_rel, -1, false, false);
2649 }
2650 #endif
2651 
2652 
2653 //=============================================================================
2654 const RegMask &JumpNode::out_RegMask() const {
2655   return RegMask::Empty;
2656 }
2657 
2658 #ifndef PRODUCT
2659 //-----------------------------related-----------------------------------------
2660 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2661 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2662 // This is regardless of compact mode.
2663 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2664   this->collect_nodes(in_rel, 1, false, false);
2665   this->collect_nodes(out_rel, -2, false, false);
2666 }
2667 #endif
2668 
2669 //=============================================================================
2670 const RegMask &JProjNode::out_RegMask() const {
2671   return RegMask::Empty;
2672 }
2673 
2674 //=============================================================================
2675 const RegMask &CProjNode::out_RegMask() const {
2676   return RegMask::Empty;
2677 }
2678 
2679 
2680 
2681 //=============================================================================
2682 
2683 uint PCTableNode::hash() const { return Node::hash() + _size; }
2684 bool PCTableNode::cmp( const Node &n ) const
2685 { return _size == ((PCTableNode&)n)._size; }
2686 
2687 const Type *PCTableNode::bottom_type() const {
2688   const Type** f = TypeTuple::fields(_size);
2689   for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2690   return TypeTuple::make(_size, f);
2691 }
2692 
2693 //------------------------------Value------------------------------------------
2694 // Compute the type of the PCTableNode.  If reachable it is a tuple of
2695 // Control, otherwise the table targets are not reachable
2696 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2697   if( phase->type(in(0)) == Type::CONTROL )
2698     return bottom_type();
2699   return Type::TOP;             // All paths dead?  Then so are we
2700 }
2701 
2702 //------------------------------Ideal------------------------------------------
2703 // Return a node which is more "ideal" than the current node.  Strip out
2704 // control copies
2705 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2706   return remove_dead_region(phase, can_reshape) ? this : NULL;
2707 }
2708 
2709 //=============================================================================
2710 uint JumpProjNode::hash() const {
2711   return Node::hash() + _dest_bci;
2712 }
2713 
2714 bool JumpProjNode::cmp( const Node &n ) const {
2715   return ProjNode::cmp(n) &&
2716     _dest_bci == ((JumpProjNode&)n)._dest_bci;
2717 }
2718 
2719 #ifndef PRODUCT
2720 void JumpProjNode::dump_spec(outputStream *st) const {
2721   ProjNode::dump_spec(st);
2722   st->print("@bci %d ",_dest_bci);
2723 }
2724 
2725 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2726   ProjNode::dump_compact_spec(st);
2727   st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2728 }
2729 
2730 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2731   // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2732   this->collect_nodes(in_rel, 1, false, false);
2733   this->collect_nodes(out_rel, -1, false, false);
2734 }
2735 #endif
2736 
2737 //=============================================================================
2738 //------------------------------Value------------------------------------------
2739 // Check for being unreachable, or for coming from a Rethrow.  Rethrow's cannot
2740 // have the default "fall_through_index" path.
2741 const Type* CatchNode::Value(PhaseGVN* phase) const {
2742   // Unreachable?  Then so are all paths from here.
2743   if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2744   // First assume all paths are reachable
2745   const Type** f = TypeTuple::fields(_size);
2746   for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2747   // Identify cases that will always throw an exception
2748   // () rethrow call
2749   // () virtual or interface call with NULL receiver
2750   // () call is a check cast with incompatible arguments
2751   if( in(1)->is_Proj() ) {
2752     Node *i10 = in(1)->in(0);
2753     if( i10->is_Call() ) {
2754       CallNode *call = i10->as_Call();
2755       // Rethrows always throw exceptions, never return
2756       if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2757         f[CatchProjNode::fall_through_index] = Type::TOP;
2758       } else if( call->req() > TypeFunc::Parms ) {
2759         const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2760         // Check for null receiver to virtual or interface calls
2761         if( call->is_CallDynamicJava() &&
2762             arg0->higher_equal(TypePtr::NULL_PTR) ) {
2763           f[CatchProjNode::fall_through_index] = Type::TOP;
2764         }
2765       } // End of if not a runtime stub
2766     } // End of if have call above me
2767   } // End of slot 1 is not a projection
2768   return TypeTuple::make(_size, f);
2769 }
2770 
2771 //=============================================================================
2772 uint CatchProjNode::hash() const {
2773   return Node::hash() + _handler_bci;
2774 }
2775 
2776 
2777 bool CatchProjNode::cmp( const Node &n ) const {
2778   return ProjNode::cmp(n) &&
2779     _handler_bci == ((CatchProjNode&)n)._handler_bci;
2780 }
2781 
2782 
2783 //------------------------------Identity---------------------------------------
2784 // If only 1 target is possible, choose it if it is the main control
2785 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2786   // If my value is control and no other value is, then treat as ID
2787   const TypeTuple *t = phase->type(in(0))->is_tuple();
2788   if (t->field_at(_con) != Type::CONTROL)  return this;
2789   // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2790   // also remove any exception table entry.  Thus we must know the call
2791   // feeding the Catch will not really throw an exception.  This is ok for
2792   // the main fall-thru control (happens when we know a call can never throw
2793   // an exception) or for "rethrow", because a further optimization will
2794   // yank the rethrow (happens when we inline a function that can throw an
2795   // exception and the caller has no handler).  Not legal, e.g., for passing
2796   // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2797   // These cases MUST throw an exception via the runtime system, so the VM
2798   // will be looking for a table entry.
2799   Node *proj = in(0)->in(1);    // Expect a proj feeding CatchNode
2800   CallNode *call;
2801   if (_con != TypeFunc::Control && // Bail out if not the main control.
2802       !(proj->is_Proj() &&      // AND NOT a rethrow
2803         proj->in(0)->is_Call() &&
2804         (call = proj->in(0)->as_Call()) &&
2805         call->entry_point() == OptoRuntime::rethrow_stub()))
2806     return this;
2807 
2808   // Search for any other path being control
2809   for (uint i = 0; i < t->cnt(); i++) {
2810     if (i != _con && t->field_at(i) == Type::CONTROL)
2811       return this;
2812   }
2813   // Only my path is possible; I am identity on control to the jump
2814   return in(0)->in(0);
2815 }
2816 
2817 
2818 #ifndef PRODUCT
2819 void CatchProjNode::dump_spec(outputStream *st) const {
2820   ProjNode::dump_spec(st);
2821   st->print("@bci %d ",_handler_bci);
2822 }
2823 #endif
2824 
2825 //=============================================================================
2826 //------------------------------Identity---------------------------------------
2827 // Check for CreateEx being Identity.
2828 Node* CreateExNode::Identity(PhaseGVN* phase) {
2829   if( phase->type(in(1)) == Type::TOP ) return in(1);
2830   if( phase->type(in(0)) == Type::TOP ) return in(0);
2831   // We only come from CatchProj, unless the CatchProj goes away.
2832   // If the CatchProj is optimized away, then we just carry the
2833   // exception oop through.
2834 
2835   // CheckCastPPNode::Ideal() for inline types reuses the exception
2836   // paths of a call to perform an allocation: we can see a Phi here.
2837   if (in(1)->is_Phi()) {
2838     return this;
2839   }
2840   CallNode *call = in(1)->in(0)->as_Call();
2841 
2842   return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2843     ? this
2844     : call->in(TypeFunc::Parms);
2845 }
2846 
2847 //=============================================================================
2848 //------------------------------Value------------------------------------------
2849 // Check for being unreachable.
2850 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2851   if (!in(0) || in(0)->is_top()) return Type::TOP;
2852   return bottom_type();
2853 }
2854 
2855 //------------------------------Ideal------------------------------------------
2856 // Check for no longer being part of a loop
2857 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2858   if (can_reshape && !in(0)->is_Region()) {
2859     // Dead code elimination can sometimes delete this projection so
2860     // if it's not there, there's nothing to do.
2861     Node* fallthru = proj_out_or_null(0);
2862     if (fallthru != NULL) {
2863       phase->is_IterGVN()->replace_node(fallthru, in(0));
2864     }
2865     return phase->C->top();
2866   }
2867   return NULL;
2868 }
2869 
2870 #ifndef PRODUCT
2871 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2872   st->print("%s", Name());
2873 }
2874 #endif