1 /*
   2  * Copyright (c) 1997, 2016, 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 "classfile/systemDictionary.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "memory/resourceArea.hpp"
  29 #include "oops/objArrayKlass.hpp"
  30 #include "opto/addnode.hpp"
  31 #include "opto/castnode.hpp"
  32 #include "opto/cfgnode.hpp"
  33 #include "opto/connode.hpp"
  34 #include "opto/convertnode.hpp"
  35 #include "opto/loopnode.hpp"
  36 #include "opto/machnode.hpp"
  37 #include "opto/movenode.hpp"
  38 #include "opto/narrowptrnode.hpp"
  39 #include "opto/mulnode.hpp"
  40 #include "opto/phaseX.hpp"
  41 #include "opto/regmask.hpp"
  42 #include "opto/runtime.hpp"
  43 #include "opto/subnode.hpp"
  44 #include "utilities/vmError.hpp"
  45 
  46 // Portions of code courtesy of Clifford Click
  47 
  48 // Optimization - Graph Style
  49 
  50 //=============================================================================
  51 //------------------------------Value------------------------------------------
  52 // Compute the type of the RegionNode.
  53 const Type* RegionNode::Value(PhaseGVN* phase) const {
  54   for( uint i=1; i<req(); ++i ) {       // For all paths in
  55     Node *n = in(i);            // Get Control source
  56     if( !n ) continue;          // Missing inputs are TOP
  57     if( phase->type(n) == Type::CONTROL )
  58       return Type::CONTROL;
  59   }
  60   return Type::TOP;             // All paths dead?  Then so are we
  61 }
  62 
  63 //------------------------------Identity---------------------------------------
  64 // Check for Region being Identity.
  65 Node* RegionNode::Identity(PhaseGVN* phase) {
  66   // Cannot have Region be an identity, even if it has only 1 input.
  67   // Phi users cannot have their Region input folded away for them,
  68   // since they need to select the proper data input
  69   return this;
  70 }
  71 
  72 //------------------------------merge_region-----------------------------------
  73 // If a Region flows into a Region, merge into one big happy merge.  This is
  74 // hard to do if there is stuff that has to happen
  75 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
  76   if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
  77     return NULL;
  78   Node *progress = NULL;        // Progress flag
  79   PhaseIterGVN *igvn = phase->is_IterGVN();
  80 
  81   uint rreq = region->req();
  82   for( uint i = 1; i < rreq; i++ ) {
  83     Node *r = region->in(i);
  84     if( r && r->Opcode() == Op_Region && // Found a region?
  85         r->in(0) == r &&        // Not already collapsed?
  86         r != region &&          // Avoid stupid situations
  87         r->outcnt() == 2 ) {    // Self user and 'region' user only?
  88       assert(!r->as_Region()->has_phi(), "no phi users");
  89       if( !progress ) {         // No progress
  90         if (region->has_phi()) {
  91           return NULL;        // Only flatten if no Phi users
  92           // igvn->hash_delete( phi );
  93         }
  94         igvn->hash_delete( region );
  95         progress = region;      // Making progress
  96       }
  97       igvn->hash_delete( r );
  98 
  99       // Append inputs to 'r' onto 'region'
 100       for( uint j = 1; j < r->req(); j++ ) {
 101         // Move an input from 'r' to 'region'
 102         region->add_req(r->in(j));
 103         r->set_req(j, phase->C->top());
 104         // Update phis of 'region'
 105         //for( uint k = 0; k < max; k++ ) {
 106         //  Node *phi = region->out(k);
 107         //  if( phi->is_Phi() ) {
 108         //    phi->add_req(phi->in(i));
 109         //  }
 110         //}
 111 
 112         rreq++;                 // One more input to Region
 113       } // Found a region to merge into Region
 114       igvn->_worklist.push(r);
 115       // Clobber pointer to the now dead 'r'
 116       region->set_req(i, phase->C->top());
 117     }
 118   }
 119 
 120   return progress;
 121 }
 122 
 123 
 124 
 125 //--------------------------------has_phi--------------------------------------
 126 // Helper function: Return any PhiNode that uses this region or NULL
 127 PhiNode* RegionNode::has_phi() const {
 128   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 129     Node* phi = fast_out(i);
 130     if (phi->is_Phi()) {   // Check for Phi users
 131       assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
 132       return phi->as_Phi();  // this one is good enough
 133     }
 134   }
 135 
 136   return NULL;
 137 }
 138 
 139 
 140 //-----------------------------has_unique_phi----------------------------------
 141 // Helper function: Return the only PhiNode that uses this region or NULL
 142 PhiNode* RegionNode::has_unique_phi() const {
 143   // Check that only one use is a Phi
 144   PhiNode* only_phi = NULL;
 145   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 146     Node* phi = fast_out(i);
 147     if (phi->is_Phi()) {   // Check for Phi users
 148       assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
 149       if (only_phi == NULL) {
 150         only_phi = phi->as_Phi();
 151       } else {
 152         return NULL;  // multiple phis
 153       }
 154     }
 155   }
 156 
 157   return only_phi;
 158 }
 159 
 160 
 161 //------------------------------check_phi_clipping-----------------------------
 162 // Helper function for RegionNode's identification of FP clipping
 163 // Check inputs to the Phi
 164 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
 165   min     = NULL;
 166   max     = NULL;
 167   val     = NULL;
 168   min_idx = 0;
 169   max_idx = 0;
 170   val_idx = 0;
 171   uint  phi_max = phi->req();
 172   if( phi_max == 4 ) {
 173     for( uint j = 1; j < phi_max; ++j ) {
 174       Node *n = phi->in(j);
 175       int opcode = n->Opcode();
 176       switch( opcode ) {
 177       case Op_ConI:
 178         {
 179           if( min == NULL ) {
 180             min     = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
 181             min_idx = j;
 182           } else {
 183             max     = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
 184             max_idx = j;
 185             if( min->get_int() > max->get_int() ) {
 186               // Swap min and max
 187               ConNode *temp;
 188               uint     temp_idx;
 189               temp     = min;     min     = max;     max     = temp;
 190               temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
 191             }
 192           }
 193         }
 194         break;
 195       default:
 196         {
 197           val = n;
 198           val_idx = j;
 199         }
 200         break;
 201       }
 202     }
 203   }
 204   return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
 205 }
 206 
 207 
 208 //------------------------------check_if_clipping------------------------------
 209 // Helper function for RegionNode's identification of FP clipping
 210 // Check that inputs to Region come from two IfNodes,
 211 //
 212 //            If
 213 //      False    True
 214 //       If        |
 215 //  False  True    |
 216 //    |      |     |
 217 //  RegionNode_inputs
 218 //
 219 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
 220   top_if = NULL;
 221   bot_if = NULL;
 222 
 223   // Check control structure above RegionNode for (if  ( if  ) )
 224   Node *in1 = region->in(1);
 225   Node *in2 = region->in(2);
 226   Node *in3 = region->in(3);
 227   // Check that all inputs are projections
 228   if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
 229     Node *in10 = in1->in(0);
 230     Node *in20 = in2->in(0);
 231     Node *in30 = in3->in(0);
 232     // Check that #1 and #2 are ifTrue and ifFalse from same If
 233     if( in10 != NULL && in10->is_If() &&
 234         in20 != NULL && in20->is_If() &&
 235         in30 != NULL && in30->is_If() && in10 == in20 &&
 236         (in1->Opcode() != in2->Opcode()) ) {
 237       Node  *in100 = in10->in(0);
 238       Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
 239       // Check that control for in10 comes from other branch of IF from in3
 240       if( in1000 != NULL && in1000->is_If() &&
 241           in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
 242         // Control pattern checks
 243         top_if = (IfNode*)in1000;
 244         bot_if = (IfNode*)in10;
 245       }
 246     }
 247   }
 248 
 249   return (top_if != NULL);
 250 }
 251 
 252 
 253 //------------------------------check_convf2i_clipping-------------------------
 254 // Helper function for RegionNode's identification of FP clipping
 255 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
 256 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
 257   convf2i = NULL;
 258 
 259   // Check for the RShiftNode
 260   Node *rshift = phi->in(idx);
 261   assert( rshift, "Previous checks ensure phi input is present");
 262   if( rshift->Opcode() != Op_RShiftI )  { return false; }
 263 
 264   // Check for the LShiftNode
 265   Node *lshift = rshift->in(1);
 266   assert( lshift, "Previous checks ensure phi input is present");
 267   if( lshift->Opcode() != Op_LShiftI )  { return false; }
 268 
 269   // Check for the ConvF2INode
 270   Node *conv = lshift->in(1);
 271   if( conv->Opcode() != Op_ConvF2I ) { return false; }
 272 
 273   // Check that shift amounts are only to get sign bits set after F2I
 274   jint max_cutoff     = max->get_int();
 275   jint min_cutoff     = min->get_int();
 276   jint left_shift     = lshift->in(2)->get_int();
 277   jint right_shift    = rshift->in(2)->get_int();
 278   jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
 279   if( left_shift != right_shift ||
 280       0 > left_shift || left_shift >= BitsPerJavaInteger ||
 281       max_post_shift < max_cutoff ||
 282       max_post_shift < -min_cutoff ) {
 283     // Shifts are necessary but current transformation eliminates them
 284     return false;
 285   }
 286 
 287   // OK to return the result of ConvF2I without shifting
 288   convf2i = (ConvF2INode*)conv;
 289   return true;
 290 }
 291 
 292 
 293 //------------------------------check_compare_clipping-------------------------
 294 // Helper function for RegionNode's identification of FP clipping
 295 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
 296   Node *i1 = iff->in(1);
 297   if ( !i1->is_Bool() ) { return false; }
 298   BoolNode *bool1 = i1->as_Bool();
 299   if(       less_than && bool1->_test._test != BoolTest::le ) { return false; }
 300   else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
 301   const Node *cmpF = bool1->in(1);
 302   if( cmpF->Opcode() != Op_CmpF )      { return false; }
 303   // Test that the float value being compared against
 304   // is equivalent to the int value used as a limit
 305   Node *nodef = cmpF->in(2);
 306   if( nodef->Opcode() != Op_ConF ) { return false; }
 307   jfloat conf = nodef->getf();
 308   jint   coni = limit->get_int();
 309   if( ((int)conf) != coni )        { return false; }
 310   input = cmpF->in(1);
 311   return true;
 312 }
 313 
 314 //------------------------------is_unreachable_region--------------------------
 315 // Find if the Region node is reachable from the root.
 316 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
 317   assert(req() == 2, "");
 318 
 319   // First, cut the simple case of fallthrough region when NONE of
 320   // region's phis references itself directly or through a data node.
 321   uint max = outcnt();
 322   uint i;
 323   for (i = 0; i < max; i++) {
 324     Node* phi = raw_out(i);
 325     if (phi != NULL && phi->is_Phi()) {
 326       assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
 327       if (phi->outcnt() == 0)
 328         continue; // Safe case - no loops
 329       if (phi->outcnt() == 1) {
 330         Node* u = phi->raw_out(0);
 331         // Skip if only one use is an other Phi or Call or Uncommon trap.
 332         // It is safe to consider this case as fallthrough.
 333         if (u != NULL && (u->is_Phi() || u->is_CFG()))
 334           continue;
 335       }
 336       // Check when phi references itself directly or through an other node.
 337       if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
 338         break; // Found possible unsafe data loop.
 339     }
 340   }
 341   if (i >= max)
 342     return false; // An unsafe case was NOT found - don't need graph walk.
 343 
 344   // Unsafe case - check if the Region node is reachable from root.
 345   ResourceMark rm;
 346 
 347   Arena *a = Thread::current()->resource_area();
 348   Node_List nstack(a);
 349   VectorSet visited(a);
 350 
 351   // Mark all control nodes reachable from root outputs
 352   Node *n = (Node*)phase->C->root();
 353   nstack.push(n);
 354   visited.set(n->_idx);
 355   while (nstack.size() != 0) {
 356     n = nstack.pop();
 357     uint max = n->outcnt();
 358     for (uint i = 0; i < max; i++) {
 359       Node* m = n->raw_out(i);
 360       if (m != NULL && m->is_CFG()) {
 361         if (phase->eqv(m, this)) {
 362           return false; // We reached the Region node - it is not dead.
 363         }
 364         if (!visited.test_set(m->_idx))
 365           nstack.push(m);
 366       }
 367     }
 368   }
 369 
 370   return true; // The Region node is unreachable - it is dead.
 371 }
 372 
 373 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) {
 374   // Incremental inlining + PhaseStringOpts sometimes produce:
 375   //
 376   // cmpP with 1 top input
 377   //           |
 378   //          If
 379   //         /  \
 380   //   IfFalse  IfTrue  /- Some Node
 381   //         \  /      /    /
 382   //        Region    / /-MergeMem
 383   //             \---Phi
 384   //
 385   //
 386   // It's expected by PhaseStringOpts that the Region goes away and is
 387   // replaced by If's control input but because there's still a Phi,
 388   // the Region stays in the graph. The top input from the cmpP is
 389   // propagated forward and a subgraph that is useful goes away. The
 390   // code below replaces the Phi with the MergeMem so that the Region
 391   // is simplified.
 392 
 393   PhiNode* phi = has_unique_phi();
 394   if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) {
 395     MergeMemNode* m = NULL;
 396     assert(phi->req() == 3, "same as region");
 397     for (uint i = 1; i < 3; ++i) {
 398       Node *mem = phi->in(i);
 399       if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) {
 400         // Nothing is control-dependent on path #i except the region itself.
 401         m = mem->as_MergeMem();
 402         uint j = 3 - i;
 403         Node* other = phi->in(j);
 404         if (other && other == m->base_memory()) {
 405           // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
 406           // This will allow the diamond to collapse completely.
 407           phase->is_IterGVN()->replace_node(phi, m);
 408           return true;
 409         }
 410       }
 411     }
 412   }
 413   return false;
 414 }
 415 
 416 //------------------------------Ideal------------------------------------------
 417 // Return a node which is more "ideal" than the current node.  Must preserve
 418 // the CFG, but we can still strip out dead paths.
 419 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 420   if( !can_reshape && !in(0) ) return NULL;     // Already degraded to a Copy
 421   assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
 422 
 423   // Check for RegionNode with no Phi users and both inputs come from either
 424   // arm of the same IF.  If found, then the control-flow split is useless.
 425   bool has_phis = false;
 426   if (can_reshape) {            // Need DU info to check for Phi users
 427     has_phis = (has_phi() != NULL);       // Cache result
 428     if (has_phis && try_clean_mem_phi(phase)) {
 429       has_phis = false;
 430     }
 431 
 432     if (!has_phis) {            // No Phi users?  Nothing merging?
 433       for (uint i = 1; i < req()-1; i++) {
 434         Node *if1 = in(i);
 435         if( !if1 ) continue;
 436         Node *iff = if1->in(0);
 437         if( !iff || !iff->is_If() ) continue;
 438         for( uint j=i+1; j<req(); j++ ) {
 439           if( in(j) && in(j)->in(0) == iff &&
 440               if1->Opcode() != in(j)->Opcode() ) {
 441             // Add the IF Projections to the worklist. They (and the IF itself)
 442             // will be eliminated if dead.
 443             phase->is_IterGVN()->add_users_to_worklist(iff);
 444             set_req(i, iff->in(0));// Skip around the useless IF diamond
 445             set_req(j, NULL);
 446             return this;      // Record progress
 447           }
 448         }
 449       }
 450     }
 451   }
 452 
 453   // Remove TOP or NULL input paths. If only 1 input path remains, this Region
 454   // degrades to a copy.
 455   bool add_to_worklist = false;
 456   bool modified = false;
 457   int cnt = 0;                  // Count of values merging
 458   DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
 459   int del_it = 0;               // The last input path we delete
 460   // For all inputs...
 461   for( uint i=1; i<req(); ++i ){// For all paths in
 462     Node *n = in(i);            // Get the input
 463     if( n != NULL ) {
 464       // Remove useless control copy inputs
 465       if( n->is_Region() && n->as_Region()->is_copy() ) {
 466         set_req(i, n->nonnull_req());
 467         modified = true;
 468         i--;
 469         continue;
 470       }
 471       if( n->is_Proj() ) {      // Remove useless rethrows
 472         Node *call = n->in(0);
 473         if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
 474           set_req(i, call->in(0));
 475           modified = true;
 476           i--;
 477           continue;
 478         }
 479       }
 480       if( phase->type(n) == Type::TOP ) {
 481         set_req(i, NULL);       // Ignore TOP inputs
 482         modified = true;
 483         i--;
 484         continue;
 485       }
 486       cnt++;                    // One more value merging
 487 
 488     } else if (can_reshape) {   // Else found dead path with DU info
 489       PhaseIterGVN *igvn = phase->is_IterGVN();
 490       del_req(i);               // Yank path from self
 491       del_it = i;
 492       uint max = outcnt();
 493       DUIterator j;
 494       bool progress = true;
 495       while(progress) {         // Need to establish property over all users
 496         progress = false;
 497         for (j = outs(); has_out(j); j++) {
 498           Node *n = out(j);
 499           if( n->req() != req() && n->is_Phi() ) {
 500             assert( n->in(0) == this, "" );
 501             igvn->hash_delete(n); // Yank from hash before hacking edges
 502             n->set_req_X(i,NULL,igvn);// Correct DU info
 503             n->del_req(i);        // Yank path from Phis
 504             if( max != outcnt() ) {
 505               progress = true;
 506               j = refresh_out_pos(j);
 507               max = outcnt();
 508             }
 509           }
 510         }
 511       }
 512       add_to_worklist = true;
 513       i--;
 514     }
 515   }
 516 
 517   if (can_reshape && cnt == 1) {
 518     // Is it dead loop?
 519     // If it is LoopNopde it had 2 (+1 itself) inputs and
 520     // one of them was cut. The loop is dead if it was EntryContol.
 521     // Loop node may have only one input because entry path
 522     // is removed in PhaseIdealLoop::Dominators().
 523     assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
 524     if (this->is_Loop() && (del_it == LoopNode::EntryControl ||
 525                             del_it == 0 && is_unreachable_region(phase)) ||
 526        !this->is_Loop() && has_phis && is_unreachable_region(phase)) {
 527       // Yes,  the region will be removed during the next step below.
 528       // Cut the backedge input and remove phis since no data paths left.
 529       // We don't cut outputs to other nodes here since we need to put them
 530       // on the worklist.
 531       PhaseIterGVN *igvn = phase->is_IterGVN();
 532       if (in(1)->outcnt() == 1) {
 533         igvn->_worklist.push(in(1));
 534       }
 535       del_req(1);
 536       cnt = 0;
 537       assert( req() == 1, "no more inputs expected" );
 538       uint max = outcnt();
 539       bool progress = true;
 540       Node *top = phase->C->top();
 541       DUIterator j;
 542       while(progress) {
 543         progress = false;
 544         for (j = outs(); has_out(j); j++) {
 545           Node *n = out(j);
 546           if( n->is_Phi() ) {
 547             assert( igvn->eqv(n->in(0), this), "" );
 548             assert( n->req() == 2 &&  n->in(1) != NULL, "Only one data input expected" );
 549             // Break dead loop data path.
 550             // Eagerly replace phis with top to avoid phis copies generation.
 551             igvn->replace_node(n, top);
 552             if( max != outcnt() ) {
 553               progress = true;
 554               j = refresh_out_pos(j);
 555               max = outcnt();
 556             }
 557           }
 558         }
 559       }
 560       add_to_worklist = true;
 561     }
 562   }
 563   if (add_to_worklist) {
 564     phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
 565   }
 566 
 567   if( cnt <= 1 ) {              // Only 1 path in?
 568     set_req(0, NULL);           // Null control input for region copy
 569     if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
 570       // No inputs or all inputs are NULL.
 571       return NULL;
 572     } else if (can_reshape) {   // Optimization phase - remove the node
 573       PhaseIterGVN *igvn = phase->is_IterGVN();
 574       Node *parent_ctrl;
 575       if( cnt == 0 ) {
 576         assert( req() == 1, "no inputs expected" );
 577         // During IGVN phase such region will be subsumed by TOP node
 578         // so region's phis will have TOP as control node.
 579         // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
 580         // Also set other user's input to top.
 581         parent_ctrl = phase->C->top();
 582       } else {
 583         // The fallthrough case since we already checked dead loops above.
 584         parent_ctrl = in(1);
 585         assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
 586         assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
 587       }
 588       if (!add_to_worklist)
 589         igvn->add_users_to_worklist(this); // Check for further allowed opts
 590       for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
 591         Node* n = last_out(i);
 592         igvn->hash_delete(n); // Remove from worklist before modifying edges
 593         if( n->is_Phi() ) {   // Collapse all Phis
 594           // Eagerly replace phis to avoid copies generation.
 595           Node* in;
 596           if( cnt == 0 ) {
 597             assert( n->req() == 1, "No data inputs expected" );
 598             in = parent_ctrl; // replaced by top
 599           } else {
 600             assert( n->req() == 2 &&  n->in(1) != NULL, "Only one data input expected" );
 601             in = n->in(1);               // replaced by unique input
 602             if( n->as_Phi()->is_unsafe_data_reference(in) )
 603               in = phase->C->top();      // replaced by top
 604           }
 605           igvn->replace_node(n, in);
 606         }
 607         else if( n->is_Region() ) { // Update all incoming edges
 608           assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
 609           uint uses_found = 0;
 610           for( uint k=1; k < n->req(); k++ ) {
 611             if( n->in(k) == this ) {
 612               n->set_req(k, parent_ctrl);
 613               uses_found++;
 614             }
 615           }
 616           if( uses_found > 1 ) { // (--i) done at the end of the loop.
 617             i -= (uses_found - 1);
 618           }
 619         }
 620         else {
 621           assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
 622           n->set_req(0, parent_ctrl);
 623         }
 624 #ifdef ASSERT
 625         for( uint k=0; k < n->req(); k++ ) {
 626           assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
 627         }
 628 #endif
 629       }
 630       // Remove the RegionNode itself from DefUse info
 631       igvn->remove_dead_node(this);
 632       return NULL;
 633     }
 634     return this;                // Record progress
 635   }
 636 
 637 
 638   // If a Region flows into a Region, merge into one big happy merge.
 639   if (can_reshape) {
 640     Node *m = merge_region(this, phase);
 641     if (m != NULL)  return m;
 642   }
 643 
 644   // Check if this region is the root of a clipping idiom on floats
 645   if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
 646     // Check that only one use is a Phi and that it simplifies to two constants +
 647     PhiNode* phi = has_unique_phi();
 648     if (phi != NULL) {          // One Phi user
 649       // Check inputs to the Phi
 650       ConNode *min;
 651       ConNode *max;
 652       Node    *val;
 653       uint     min_idx;
 654       uint     max_idx;
 655       uint     val_idx;
 656       if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx )  ) {
 657         IfNode *top_if;
 658         IfNode *bot_if;
 659         if( check_if_clipping( this, bot_if, top_if ) ) {
 660           // Control pattern checks, now verify compares
 661           Node   *top_in = NULL;   // value being compared against
 662           Node   *bot_in = NULL;
 663           if( check_compare_clipping( true,  bot_if, min, bot_in ) &&
 664               check_compare_clipping( false, top_if, max, top_in ) ) {
 665             if( bot_in == top_in ) {
 666               PhaseIterGVN *gvn = phase->is_IterGVN();
 667               assert( gvn != NULL, "Only had DefUse info in IterGVN");
 668               // Only remaining check is that bot_in == top_in == (Phi's val + mods)
 669 
 670               // Check for the ConvF2INode
 671               ConvF2INode *convf2i;
 672               if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
 673                 convf2i->in(1) == bot_in ) {
 674                 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
 675                 // max test
 676                 Node *cmp   = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
 677                 Node *boo   = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
 678                 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
 679                 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
 680                 Node *ifF   = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
 681                 // min test
 682                 cmp         = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
 683                 boo         = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
 684                 iff         = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
 685                 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
 686                 ifF         = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
 687                 // update input edges to region node
 688                 set_req_X( min_idx, if_min, gvn );
 689                 set_req_X( max_idx, if_max, gvn );
 690                 set_req_X( val_idx, ifF,    gvn );
 691                 // remove unnecessary 'LShiftI; RShiftI' idiom
 692                 gvn->hash_delete(phi);
 693                 phi->set_req_X( val_idx, convf2i, gvn );
 694                 gvn->hash_find_insert(phi);
 695                 // Return transformed region node
 696                 return this;
 697               }
 698             }
 699           }
 700         }
 701       }
 702     }
 703   }
 704 
 705   return modified ? this : NULL;
 706 }
 707 
 708 
 709 
 710 const RegMask &RegionNode::out_RegMask() const {
 711   return RegMask::Empty;
 712 }
 713 
 714 // Find the one non-null required input.  RegionNode only
 715 Node *Node::nonnull_req() const {
 716   assert( is_Region(), "" );
 717   for( uint i = 1; i < _cnt; i++ )
 718     if( in(i) )
 719       return in(i);
 720   ShouldNotReachHere();
 721   return NULL;
 722 }
 723 
 724 
 725 //=============================================================================
 726 // note that these functions assume that the _adr_type field is flattened
 727 uint PhiNode::hash() const {
 728   const Type* at = _adr_type;
 729   return TypeNode::hash() + (at ? at->hash() : 0);
 730 }
 731 uint PhiNode::cmp( const Node &n ) const {
 732   return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
 733 }
 734 static inline
 735 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
 736   if (at == NULL || at == TypePtr::BOTTOM)  return at;
 737   return Compile::current()->alias_type(at)->adr_type();
 738 }
 739 
 740 //----------------------------make---------------------------------------------
 741 // create a new phi with edges matching r and set (initially) to x
 742 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
 743   uint preds = r->req();   // Number of predecessor paths
 744   assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
 745   PhiNode* p = new PhiNode(r, t, at);
 746   for (uint j = 1; j < preds; j++) {
 747     // Fill in all inputs, except those which the region does not yet have
 748     if (r->in(j) != NULL)
 749       p->init_req(j, x);
 750   }
 751   return p;
 752 }
 753 PhiNode* PhiNode::make(Node* r, Node* x) {
 754   const Type*    t  = x->bottom_type();
 755   const TypePtr* at = NULL;
 756   if (t == Type::MEMORY)  at = flatten_phi_adr_type(x->adr_type());
 757   return make(r, x, t, at);
 758 }
 759 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
 760   const Type*    t  = x->bottom_type();
 761   const TypePtr* at = NULL;
 762   if (t == Type::MEMORY)  at = flatten_phi_adr_type(x->adr_type());
 763   return new PhiNode(r, t, at);
 764 }
 765 
 766 
 767 //------------------------slice_memory-----------------------------------------
 768 // create a new phi with narrowed memory type
 769 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
 770   PhiNode* mem = (PhiNode*) clone();
 771   *(const TypePtr**)&mem->_adr_type = adr_type;
 772   // convert self-loops, or else we get a bad graph
 773   for (uint i = 1; i < req(); i++) {
 774     if ((const Node*)in(i) == this)  mem->set_req(i, mem);
 775   }
 776   mem->verify_adr_type();
 777   return mem;
 778 }
 779 
 780 //------------------------split_out_instance-----------------------------------
 781 // Split out an instance type from a bottom phi.
 782 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
 783   const TypeOopPtr *t_oop = at->isa_oopptr();
 784   assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
 785   const TypePtr *t = adr_type();
 786   assert(type() == Type::MEMORY &&
 787          (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
 788           t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
 789           t->is_oopptr()->cast_to_exactness(true)
 790            ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
 791            ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
 792          "bottom or raw memory required");
 793 
 794   // Check if an appropriate node already exists.
 795   Node *region = in(0);
 796   for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
 797     Node* use = region->fast_out(k);
 798     if( use->is_Phi()) {
 799       PhiNode *phi2 = use->as_Phi();
 800       if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
 801         return phi2;
 802       }
 803     }
 804   }
 805   Compile *C = igvn->C;
 806   Arena *a = Thread::current()->resource_area();
 807   Node_Array node_map = new Node_Array(a);
 808   Node_Stack stack(a, C->live_nodes() >> 4);
 809   PhiNode *nphi = slice_memory(at);
 810   igvn->register_new_node_with_optimizer( nphi );
 811   node_map.map(_idx, nphi);
 812   stack.push((Node *)this, 1);
 813   while(!stack.is_empty()) {
 814     PhiNode *ophi = stack.node()->as_Phi();
 815     uint i = stack.index();
 816     assert(i >= 1, "not control edge");
 817     stack.pop();
 818     nphi = node_map[ophi->_idx]->as_Phi();
 819     for (; i < ophi->req(); i++) {
 820       Node *in = ophi->in(i);
 821       if (in == NULL || igvn->type(in) == Type::TOP)
 822         continue;
 823       Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
 824       PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
 825       if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
 826         opt = node_map[optphi->_idx];
 827         if (opt == NULL) {
 828           stack.push(ophi, i);
 829           nphi = optphi->slice_memory(at);
 830           igvn->register_new_node_with_optimizer( nphi );
 831           node_map.map(optphi->_idx, nphi);
 832           ophi = optphi;
 833           i = 0; // will get incremented at top of loop
 834           continue;
 835         }
 836       }
 837       nphi->set_req(i, opt);
 838     }
 839   }
 840   return nphi;
 841 }
 842 
 843 //------------------------verify_adr_type--------------------------------------
 844 #ifdef ASSERT
 845 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
 846   if (visited.test_set(_idx))  return;  //already visited
 847 
 848   // recheck constructor invariants:
 849   verify_adr_type(false);
 850 
 851   // recheck local phi/phi consistency:
 852   assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
 853          "adr_type must be consistent across phi nest");
 854 
 855   // walk around
 856   for (uint i = 1; i < req(); i++) {
 857     Node* n = in(i);
 858     if (n == NULL)  continue;
 859     const Node* np = in(i);
 860     if (np->is_Phi()) {
 861       np->as_Phi()->verify_adr_type(visited, at);
 862     } else if (n->bottom_type() == Type::TOP
 863                || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
 864       // ignore top inputs
 865     } else {
 866       const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
 867       // recheck phi/non-phi consistency at leaves:
 868       assert((nat != NULL) == (at != NULL), "");
 869       assert(nat == at || nat == TypePtr::BOTTOM,
 870              "adr_type must be consistent at leaves of phi nest");
 871     }
 872   }
 873 }
 874 
 875 // Verify a whole nest of phis rooted at this one.
 876 void PhiNode::verify_adr_type(bool recursive) const {
 877   if (VMError::is_error_reported())  return;  // muzzle asserts when debugging an error
 878   if (Node::in_dump())               return;  // muzzle asserts when printing
 879 
 880   assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
 881 
 882   if (!VerifyAliases)       return;  // verify thoroughly only if requested
 883 
 884   assert(_adr_type == flatten_phi_adr_type(_adr_type),
 885          "Phi::adr_type must be pre-normalized");
 886 
 887   if (recursive) {
 888     VectorSet visited(Thread::current()->resource_area());
 889     verify_adr_type(visited, _adr_type);
 890   }
 891 }
 892 #endif
 893 
 894 
 895 //------------------------------Value------------------------------------------
 896 // Compute the type of the PhiNode
 897 const Type* PhiNode::Value(PhaseGVN* phase) const {
 898   Node *r = in(0);              // RegionNode
 899   if( !r )                      // Copy or dead
 900     return in(1) ? phase->type(in(1)) : Type::TOP;
 901 
 902   // Note: During parsing, phis are often transformed before their regions.
 903   // This means we have to use type_or_null to defend against untyped regions.
 904   if( phase->type_or_null(r) == Type::TOP )  // Dead code?
 905     return Type::TOP;
 906 
 907   // Check for trip-counted loop.  If so, be smarter.
 908   CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
 909   if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
 910     // protect against init_trip() or limit() returning NULL
 911     if (l->can_be_counted_loop(phase)) {
 912       const Node *init   = l->init_trip();
 913       const Node *limit  = l->limit();
 914       const Node* stride = l->stride();
 915       if (init != NULL && limit != NULL && stride != NULL) {
 916         const TypeInt* lo = phase->type(init)->isa_int();
 917         const TypeInt* hi = phase->type(limit)->isa_int();
 918         const TypeInt* stride_t = phase->type(stride)->isa_int();
 919         if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
 920           assert(stride_t->_hi >= stride_t->_lo, "bad stride type");
 921           if (stride_t->_hi < 0) {          // Down-counter loop
 922             swap(lo, hi);
 923             return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3);
 924           } else if (stride_t->_lo >= 0) {
 925             return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3);
 926           }
 927         }
 928       }
 929     } else if (l->in(LoopNode::LoopBackControl) != NULL &&
 930                in(LoopNode::EntryControl) != NULL &&
 931                phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
 932       // During CCP, if we saturate the type of a counted loop's Phi
 933       // before the special code for counted loop above has a chance
 934       // to run (that is as long as the type of the backedge's control
 935       // is top), we might end up with non monotonic types
 936       return phase->type(in(LoopNode::EntryControl));
 937     }
 938   }
 939 
 940   // Until we have harmony between classes and interfaces in the type
 941   // lattice, we must tread carefully around phis which implicitly
 942   // convert the one to the other.
 943   const TypePtr* ttp = _type->make_ptr();
 944   const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
 945   const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
 946   bool is_intf = false;
 947   if (ttip != NULL) {
 948     ciKlass* k = ttip->klass();
 949     if (k->is_loaded() && k->is_interface())
 950       is_intf = true;
 951   }
 952   if (ttkp != NULL) {
 953     ciKlass* k = ttkp->klass();
 954     if (k->is_loaded() && k->is_interface())
 955       is_intf = true;
 956   }
 957 
 958   // Default case: merge all inputs
 959   const Type *t = Type::TOP;        // Merged type starting value
 960   for (uint i = 1; i < req(); ++i) {// For all paths in
 961     // Reachable control path?
 962     if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
 963       const Type* ti = phase->type(in(i));
 964       // We assume that each input of an interface-valued Phi is a true
 965       // subtype of that interface.  This might not be true of the meet
 966       // of all the input types.  The lattice is not distributive in
 967       // such cases.  Ward off asserts in type.cpp by refusing to do
 968       // meets between interfaces and proper classes.
 969       const TypePtr* tip = ti->make_ptr();
 970       const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
 971       if (tiip) {
 972         bool ti_is_intf = false;
 973         ciKlass* k = tiip->klass();
 974         if (k->is_loaded() && k->is_interface())
 975           ti_is_intf = true;
 976         if (is_intf != ti_is_intf)
 977           { t = _type; break; }
 978       }
 979       t = t->meet_speculative(ti);
 980     }
 981   }
 982 
 983   // The worst-case type (from ciTypeFlow) should be consistent with "t".
 984   // That is, we expect that "t->higher_equal(_type)" holds true.
 985   // There are various exceptions:
 986   // - Inputs which are phis might in fact be widened unnecessarily.
 987   //   For example, an input might be a widened int while the phi is a short.
 988   // - Inputs might be BotPtrs but this phi is dependent on a null check,
 989   //   and postCCP has removed the cast which encodes the result of the check.
 990   // - The type of this phi is an interface, and the inputs are classes.
 991   // - Value calls on inputs might produce fuzzy results.
 992   //   (Occurrences of this case suggest improvements to Value methods.)
 993   //
 994   // It is not possible to see Type::BOTTOM values as phi inputs,
 995   // because the ciTypeFlow pre-pass produces verifier-quality types.
 996   const Type* ft = t->filter_speculative(_type);  // Worst case type
 997 
 998 #ifdef ASSERT
 999   // The following logic has been moved into TypeOopPtr::filter.
1000   const Type* jt = t->join_speculative(_type);
1001   if (jt->empty()) {           // Emptied out???
1002 
1003     // Check for evil case of 't' being a class and '_type' expecting an
1004     // interface.  This can happen because the bytecodes do not contain
1005     // enough type info to distinguish a Java-level interface variable
1006     // from a Java-level object variable.  If we meet 2 classes which
1007     // both implement interface I, but their meet is at 'j/l/O' which
1008     // doesn't implement I, we have no way to tell if the result should
1009     // be 'I' or 'j/l/O'.  Thus we'll pick 'j/l/O'.  If this then flows
1010     // into a Phi which "knows" it's an Interface type we'll have to
1011     // uplift the type.
1012     if (!t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface()) {
1013       assert(ft == _type, ""); // Uplift to interface
1014     } else if (!t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1015       assert(ft == _type, ""); // Uplift to interface
1016     } else {
1017       // We also have to handle 'evil cases' of interface- vs. class-arrays
1018       Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1019       if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1020           assert(ft == _type, "");   // Uplift to array of interface
1021       } else {
1022         // Otherwise it's something stupid like non-overlapping int ranges
1023         // found on dying counted loops.
1024         assert(ft == Type::TOP, ""); // Canonical empty value
1025       }
1026     }
1027   }
1028 
1029   else {
1030 
1031     // If we have an interface-typed Phi and we narrow to a class type, the join
1032     // should report back the class.  However, if we have a J/L/Object
1033     // class-typed Phi and an interface flows in, it's possible that the meet &
1034     // join report an interface back out.  This isn't possible but happens
1035     // because the type system doesn't interact well with interfaces.
1036     const TypePtr *jtp = jt->make_ptr();
1037     const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1038     const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1039     if( jtip && ttip ) {
1040       if( jtip->is_loaded() &&  jtip->klass()->is_interface() &&
1041           ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1042         assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1043                ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1044         jt = ft;
1045       }
1046     }
1047     if( jtkp && ttkp ) {
1048       if( jtkp->is_loaded() &&  jtkp->klass()->is_interface() &&
1049           !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1050           ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1051         assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1052                ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1053         jt = ft;
1054       }
1055     }
1056     if (jt != ft && jt->base() == ft->base()) {
1057       if (jt->isa_int() &&
1058           jt->is_int()->_lo == ft->is_int()->_lo &&
1059           jt->is_int()->_hi == ft->is_int()->_hi)
1060         jt = ft;
1061       if (jt->isa_long() &&
1062           jt->is_long()->_lo == ft->is_long()->_lo &&
1063           jt->is_long()->_hi == ft->is_long()->_hi)
1064         jt = ft;
1065     }
1066     if (jt != ft) {
1067       tty->print("merge type:  "); t->dump(); tty->cr();
1068       tty->print("kill type:   "); _type->dump(); tty->cr();
1069       tty->print("join type:   "); jt->dump(); tty->cr();
1070       tty->print("filter type: "); ft->dump(); tty->cr();
1071     }
1072     assert(jt == ft, "");
1073   }
1074 #endif //ASSERT
1075 
1076   // Deal with conversion problems found in data loops.
1077   ft = phase->saturate(ft, phase->type_or_null(this), _type);
1078 
1079   return ft;
1080 }
1081 
1082 
1083 //------------------------------is_diamond_phi---------------------------------
1084 // Does this Phi represent a simple well-shaped diamond merge?  Return the
1085 // index of the true path or 0 otherwise.
1086 // If check_control_only is true, do not inspect the If node at the
1087 // top, and return -1 (not an edge number) on success.
1088 int PhiNode::is_diamond_phi(bool check_control_only) const {
1089   // Check for a 2-path merge
1090   Node *region = in(0);
1091   if( !region ) return 0;
1092   if( region->req() != 3 ) return 0;
1093   if(         req() != 3 ) return 0;
1094   // Check that both paths come from the same If
1095   Node *ifp1 = region->in(1);
1096   Node *ifp2 = region->in(2);
1097   if( !ifp1 || !ifp2 ) return 0;
1098   Node *iff = ifp1->in(0);
1099   if( !iff || !iff->is_If() ) return 0;
1100   if( iff != ifp2->in(0) ) return 0;
1101   if (check_control_only)  return -1;
1102   // Check for a proper bool/cmp
1103   const Node *b = iff->in(1);
1104   if( !b->is_Bool() ) return 0;
1105   const Node *cmp = b->in(1);
1106   if( !cmp->is_Cmp() ) return 0;
1107 
1108   // Check for branching opposite expected
1109   if( ifp2->Opcode() == Op_IfTrue ) {
1110     assert( ifp1->Opcode() == Op_IfFalse, "" );
1111     return 2;
1112   } else {
1113     assert( ifp1->Opcode() == Op_IfTrue, "" );
1114     return 1;
1115   }
1116 }
1117 
1118 //----------------------------check_cmove_id-----------------------------------
1119 // Check for CMove'ing a constant after comparing against the constant.
1120 // Happens all the time now, since if we compare equality vs a constant in
1121 // the parser, we "know" the variable is constant on one path and we force
1122 // it.  Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1123 // conditional move: "x = (x==0)?0:x;".  Yucko.  This fix is slightly more
1124 // general in that we don't need constants.  Since CMove's are only inserted
1125 // in very special circumstances, we do it here on generic Phi's.
1126 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1127   assert(true_path !=0, "only diamond shape graph expected");
1128 
1129   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1130   // phi->region->if_proj->ifnode->bool->cmp
1131   Node*     region = in(0);
1132   Node*     iff    = region->in(1)->in(0);
1133   BoolNode* b      = iff->in(1)->as_Bool();
1134   Node*     cmp    = b->in(1);
1135   Node*     tval   = in(true_path);
1136   Node*     fval   = in(3-true_path);
1137   Node*     id     = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1138   if (id == NULL)
1139     return NULL;
1140 
1141   // Either value might be a cast that depends on a branch of 'iff'.
1142   // Since the 'id' value will float free of the diamond, either
1143   // decast or return failure.
1144   Node* ctl = id->in(0);
1145   if (ctl != NULL && ctl->in(0) == iff) {
1146     if (id->is_ConstraintCast()) {
1147       return id->in(1);
1148     } else {
1149       // Don't know how to disentangle this value.
1150       return NULL;
1151     }
1152   }
1153 
1154   return id;
1155 }
1156 
1157 //------------------------------Identity---------------------------------------
1158 // Check for Region being Identity.
1159 Node* PhiNode::Identity(PhaseGVN* phase) {
1160   // Check for no merging going on
1161   // (There used to be special-case code here when this->region->is_Loop.
1162   // It would check for a tributary phi on the backedge that the main phi
1163   // trivially, perhaps with a single cast.  The unique_input method
1164   // does all this and more, by reducing such tributaries to 'this'.)
1165   Node* uin = unique_input(phase, false);
1166   if (uin != NULL) {
1167     return uin;
1168   }
1169 
1170   int true_path = is_diamond_phi();
1171   if (true_path != 0) {
1172     Node* id = is_cmove_id(phase, true_path);
1173     if (id != NULL)  return id;
1174   }
1175 
1176   return this;                     // No identity
1177 }
1178 
1179 //-----------------------------unique_input------------------------------------
1180 // Find the unique value, discounting top, self-loops, and casts.
1181 // Return top if there are no inputs, and self if there are multiple.
1182 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1183   //  1) One unique direct input,
1184   // or if uncast is true:
1185   //  2) some of the inputs have an intervening ConstraintCast
1186   //  3) an input is a self loop
1187   //
1188   //  1) input   or   2) input     or   3) input __
1189   //     /   \           /   \               \  /  \
1190   //     \   /          |    cast             phi  cast
1191   //      phi            \   /               /  \  /
1192   //                      phi               /    --
1193 
1194   Node* r = in(0);                      // RegionNode
1195   if (r == NULL)  return in(1);         // Already degraded to a Copy
1196   Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1197 
1198   for (uint i = 1, cnt = req(); i < cnt; ++i) {
1199     Node* rc = r->in(i);
1200     if (rc == NULL || phase->type(rc) == Type::TOP)
1201       continue;                 // ignore unreachable control path
1202     Node* n = in(i);
1203     if (n == NULL)
1204       continue;
1205     Node* un = n;
1206     if (uncast) {
1207 #ifdef ASSERT
1208       Node* m = un->uncast();
1209 #endif
1210       while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1211         Node* next = un->in(1);
1212         if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1213           // risk exposing raw ptr at safepoint
1214           break;
1215         }
1216         un = next;
1217       }
1218       assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1219     }
1220     if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1221       continue; // ignore if top, or in(i) and "this" are in a data cycle
1222     }
1223     // Check for a unique input (maybe uncasted)
1224     if (input == NULL) {
1225       input = un;
1226     } else if (input != un) {
1227       input = NodeSentinel; // no unique input
1228     }
1229   }
1230   if (input == NULL) {
1231     return phase->C->top();        // no inputs
1232   }
1233 
1234   if (input != NodeSentinel) {
1235     return input;           // one unique direct input
1236   }
1237 
1238   // Nothing.
1239   return NULL;
1240 }
1241 
1242 //------------------------------is_x2logic-------------------------------------
1243 // Check for simple convert-to-boolean pattern
1244 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1245 // Convert Phi to an ConvIB.
1246 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1247   assert(true_path !=0, "only diamond shape graph expected");
1248   // Convert the true/false index into an expected 0/1 return.
1249   // Map 2->0 and 1->1.
1250   int flipped = 2-true_path;
1251 
1252   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1253   // phi->region->if_proj->ifnode->bool->cmp
1254   Node *region = phi->in(0);
1255   Node *iff = region->in(1)->in(0);
1256   BoolNode *b = (BoolNode*)iff->in(1);
1257   const CmpNode *cmp = (CmpNode*)b->in(1);
1258 
1259   Node *zero = phi->in(1);
1260   Node *one  = phi->in(2);
1261   const Type *tzero = phase->type( zero );
1262   const Type *tone  = phase->type( one  );
1263 
1264   // Check for compare vs 0
1265   const Type *tcmp = phase->type(cmp->in(2));
1266   if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1267     // Allow cmp-vs-1 if the other input is bounded by 0-1
1268     if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1269       return NULL;
1270     flipped = 1-flipped;        // Test is vs 1 instead of 0!
1271   }
1272 
1273   // Check for setting zero/one opposite expected
1274   if( tzero == TypeInt::ZERO ) {
1275     if( tone == TypeInt::ONE ) {
1276     } else return NULL;
1277   } else if( tzero == TypeInt::ONE ) {
1278     if( tone == TypeInt::ZERO ) {
1279       flipped = 1-flipped;
1280     } else return NULL;
1281   } else return NULL;
1282 
1283   // Check for boolean test backwards
1284   if( b->_test._test == BoolTest::ne ) {
1285   } else if( b->_test._test == BoolTest::eq ) {
1286     flipped = 1-flipped;
1287   } else return NULL;
1288 
1289   // Build int->bool conversion
1290   Node *n = new Conv2BNode( cmp->in(1) );
1291   if( flipped )
1292     n = new XorINode( phase->transform(n), phase->intcon(1) );
1293 
1294   return n;
1295 }
1296 
1297 //------------------------------is_cond_add------------------------------------
1298 // Check for simple conditional add pattern:  "(P < Q) ? X+Y : X;"
1299 // To be profitable the control flow has to disappear; there can be no other
1300 // values merging here.  We replace the test-and-branch with:
1301 // "(sgn(P-Q))&Y) + X".  Basically, convert "(P < Q)" into 0 or -1 by
1302 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1303 // Then convert Y to 0-or-Y and finally add.
1304 // This is a key transform for SpecJava _201_compress.
1305 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1306   assert(true_path !=0, "only diamond shape graph expected");
1307 
1308   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1309   // phi->region->if_proj->ifnode->bool->cmp
1310   RegionNode *region = (RegionNode*)phi->in(0);
1311   Node *iff = region->in(1)->in(0);
1312   BoolNode* b = iff->in(1)->as_Bool();
1313   const CmpNode *cmp = (CmpNode*)b->in(1);
1314 
1315   // Make sure only merging this one phi here
1316   if (region->has_unique_phi() != phi)  return NULL;
1317 
1318   // Make sure each arm of the diamond has exactly one output, which we assume
1319   // is the region.  Otherwise, the control flow won't disappear.
1320   if (region->in(1)->outcnt() != 1) return NULL;
1321   if (region->in(2)->outcnt() != 1) return NULL;
1322 
1323   // Check for "(P < Q)" of type signed int
1324   if (b->_test._test != BoolTest::lt)  return NULL;
1325   if (cmp->Opcode() != Op_CmpI)        return NULL;
1326 
1327   Node *p = cmp->in(1);
1328   Node *q = cmp->in(2);
1329   Node *n1 = phi->in(  true_path);
1330   Node *n2 = phi->in(3-true_path);
1331 
1332   int op = n1->Opcode();
1333   if( op != Op_AddI           // Need zero as additive identity
1334       /*&&op != Op_SubI &&
1335       op != Op_AddP &&
1336       op != Op_XorI &&
1337       op != Op_OrI*/ )
1338     return NULL;
1339 
1340   Node *x = n2;
1341   Node *y = NULL;
1342   if( x == n1->in(1) ) {
1343     y = n1->in(2);
1344   } else if( x == n1->in(2) ) {
1345     y = n1->in(1);
1346   } else return NULL;
1347 
1348   // Not so profitable if compare and add are constants
1349   if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1350     return NULL;
1351 
1352   Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1353   Node *j_and   = phase->transform( new AndINode(cmplt,y) );
1354   return new AddINode(j_and,x);
1355 }
1356 
1357 //------------------------------is_absolute------------------------------------
1358 // Check for absolute value.
1359 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1360   assert(true_path !=0, "only diamond shape graph expected");
1361 
1362   int  cmp_zero_idx = 0;        // Index of compare input where to look for zero
1363   int  phi_x_idx = 0;           // Index of phi input where to find naked x
1364 
1365   // ABS ends with the merge of 2 control flow paths.
1366   // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1367   int false_path = 3 - true_path;
1368 
1369   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1370   // phi->region->if_proj->ifnode->bool->cmp
1371   BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1372 
1373   // Check bool sense
1374   switch( bol->_test._test ) {
1375   case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path;  break;
1376   case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1377   case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path;  break;
1378   case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1379   default:           return NULL;                              break;
1380   }
1381 
1382   // Test is next
1383   Node *cmp = bol->in(1);
1384   const Type *tzero = NULL;
1385   switch( cmp->Opcode() ) {
1386   case Op_CmpF:    tzero = TypeF::ZERO; break; // Float ABS
1387   case Op_CmpD:    tzero = TypeD::ZERO; break; // Double ABS
1388   default: return NULL;
1389   }
1390 
1391   // Find zero input of compare; the other input is being abs'd
1392   Node *x = NULL;
1393   bool flip = false;
1394   if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1395     x = cmp->in(3 - cmp_zero_idx);
1396   } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1397     // The test is inverted, we should invert the result...
1398     x = cmp->in(cmp_zero_idx);
1399     flip = true;
1400   } else {
1401     return NULL;
1402   }
1403 
1404   // Next get the 2 pieces being selected, one is the original value
1405   // and the other is the negated value.
1406   if( phi_root->in(phi_x_idx) != x ) return NULL;
1407 
1408   // Check other phi input for subtract node
1409   Node *sub = phi_root->in(3 - phi_x_idx);
1410 
1411   // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1412   if( tzero == TypeF::ZERO ) {
1413     if( sub->Opcode() != Op_SubF ||
1414         sub->in(2) != x ||
1415         phase->type(sub->in(1)) != tzero ) return NULL;
1416     x = new AbsFNode(x);
1417     if (flip) {
1418       x = new SubFNode(sub->in(1), phase->transform(x));
1419     }
1420   } else {
1421     if( sub->Opcode() != Op_SubD ||
1422         sub->in(2) != x ||
1423         phase->type(sub->in(1)) != tzero ) return NULL;
1424     x = new AbsDNode(x);
1425     if (flip) {
1426       x = new SubDNode(sub->in(1), phase->transform(x));
1427     }
1428   }
1429 
1430   return x;
1431 }
1432 
1433 //------------------------------split_once-------------------------------------
1434 // Helper for split_flow_path
1435 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1436   igvn->hash_delete(n);         // Remove from hash before hacking edges
1437 
1438   uint j = 1;
1439   for (uint i = phi->req()-1; i > 0; i--) {
1440     if (phi->in(i) == val) {   // Found a path with val?
1441       // Add to NEW Region/Phi, no DU info
1442       newn->set_req( j++, n->in(i) );
1443       // Remove from OLD Region/Phi
1444       n->del_req(i);
1445     }
1446   }
1447 
1448   // Register the new node but do not transform it.  Cannot transform until the
1449   // entire Region/Phi conglomerate has been hacked as a single huge transform.
1450   igvn->register_new_node_with_optimizer( newn );
1451 
1452   // Now I can point to the new node.
1453   n->add_req(newn);
1454   igvn->_worklist.push(n);
1455 }
1456 
1457 //------------------------------split_flow_path--------------------------------
1458 // Check for merging identical values and split flow paths
1459 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1460   BasicType bt = phi->type()->basic_type();
1461   if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1462     return NULL;                // Bail out on funny non-value stuff
1463   if( phi->req() <= 3 )         // Need at least 2 matched inputs and a
1464     return NULL;                // third unequal input to be worth doing
1465 
1466   // Scan for a constant
1467   uint i;
1468   for( i = 1; i < phi->req()-1; i++ ) {
1469     Node *n = phi->in(i);
1470     if( !n ) return NULL;
1471     if( phase->type(n) == Type::TOP ) return NULL;
1472     if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1473       break;
1474   }
1475   if( i >= phi->req() )         // Only split for constants
1476     return NULL;
1477 
1478   Node *val = phi->in(i);       // Constant to split for
1479   uint hit = 0;                 // Number of times it occurs
1480   Node *r = phi->region();
1481 
1482   for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1483     Node *n = phi->in(i);
1484     if( !n ) return NULL;
1485     if( phase->type(n) == Type::TOP ) return NULL;
1486     if( phi->in(i) == val ) {
1487       hit++;
1488       if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1489         return NULL;            // don't split loop entry path
1490       }
1491     }
1492   }
1493 
1494   if( hit <= 1 ||               // Make sure we find 2 or more
1495       hit == phi->req()-1 )     // and not ALL the same value
1496     return NULL;
1497 
1498   // Now start splitting out the flow paths that merge the same value.
1499   // Split first the RegionNode.
1500   PhaseIterGVN *igvn = phase->is_IterGVN();
1501   RegionNode *newr = new RegionNode(hit+1);
1502   split_once(igvn, phi, val, r, newr);
1503 
1504   // Now split all other Phis than this one
1505   for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1506     Node* phi2 = r->fast_out(k);
1507     if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1508       PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1509       split_once(igvn, phi, val, phi2, newphi);
1510     }
1511   }
1512 
1513   // Clean up this guy
1514   igvn->hash_delete(phi);
1515   for( i = phi->req()-1; i > 0; i-- ) {
1516     if( phi->in(i) == val ) {
1517       phi->del_req(i);
1518     }
1519   }
1520   phi->add_req(val);
1521 
1522   return phi;
1523 }
1524 
1525 //=============================================================================
1526 //------------------------------simple_data_loop_check-------------------------
1527 //  Try to determining if the phi node in a simple safe/unsafe data loop.
1528 //  Returns:
1529 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1530 // Safe       - safe case when the phi and it's inputs reference only safe data
1531 //              nodes;
1532 // Unsafe     - the phi and it's inputs reference unsafe data nodes but there
1533 //              is no reference back to the phi - need a graph walk
1534 //              to determine if it is in a loop;
1535 // UnsafeLoop - unsafe case when the phi references itself directly or through
1536 //              unsafe data node.
1537 //  Note: a safe data node is a node which could/never reference itself during
1538 //  GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1539 //  I mark Phi nodes as safe node not only because they can reference itself
1540 //  but also to prevent mistaking the fallthrough case inside an outer loop
1541 //  as dead loop when the phi references itselfs through an other phi.
1542 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1543   // It is unsafe loop if the phi node references itself directly.
1544   if (in == (Node*)this)
1545     return UnsafeLoop; // Unsafe loop
1546   // Unsafe loop if the phi node references itself through an unsafe data node.
1547   // Exclude cases with null inputs or data nodes which could reference
1548   // itself (safe for dead loops).
1549   if (in != NULL && !in->is_dead_loop_safe()) {
1550     // Check inputs of phi's inputs also.
1551     // It is much less expensive then full graph walk.
1552     uint cnt = in->req();
1553     uint i = (in->is_Proj() && !in->is_CFG())  ? 0 : 1;
1554     for (; i < cnt; ++i) {
1555       Node* m = in->in(i);
1556       if (m == (Node*)this)
1557         return UnsafeLoop; // Unsafe loop
1558       if (m != NULL && !m->is_dead_loop_safe()) {
1559         // Check the most common case (about 30% of all cases):
1560         // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1561         Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1562         if (m1 == (Node*)this)
1563           return UnsafeLoop; // Unsafe loop
1564         if (m1 != NULL && m1 == m->in(2) &&
1565             m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1566           continue; // Safe case
1567         }
1568         // The phi references an unsafe node - need full analysis.
1569         return Unsafe;
1570       }
1571     }
1572   }
1573   return Safe; // Safe case - we can optimize the phi node.
1574 }
1575 
1576 //------------------------------is_unsafe_data_reference-----------------------
1577 // If phi can be reached through the data input - it is data loop.
1578 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1579   assert(req() > 1, "");
1580   // First, check simple cases when phi references itself directly or
1581   // through an other node.
1582   LoopSafety safety = simple_data_loop_check(in);
1583   if (safety == UnsafeLoop)
1584     return true;  // phi references itself - unsafe loop
1585   else if (safety == Safe)
1586     return false; // Safe case - phi could be replaced with the unique input.
1587 
1588   // Unsafe case when we should go through data graph to determine
1589   // if the phi references itself.
1590 
1591   ResourceMark rm;
1592 
1593   Arena *a = Thread::current()->resource_area();
1594   Node_List nstack(a);
1595   VectorSet visited(a);
1596 
1597   nstack.push(in); // Start with unique input.
1598   visited.set(in->_idx);
1599   while (nstack.size() != 0) {
1600     Node* n = nstack.pop();
1601     uint cnt = n->req();
1602     uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1603     for (; i < cnt; i++) {
1604       Node* m = n->in(i);
1605       if (m == (Node*)this) {
1606         return true;    // Data loop
1607       }
1608       if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1609         if (!visited.test_set(m->_idx))
1610           nstack.push(m);
1611       }
1612     }
1613   }
1614   return false; // The phi is not reachable from its inputs
1615 }
1616 
1617 
1618 //------------------------------Ideal------------------------------------------
1619 // Return a node which is more "ideal" than the current node.  Must preserve
1620 // the CFG, but we can still strip out dead paths.
1621 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1622   // The next should never happen after 6297035 fix.
1623   if( is_copy() )               // Already degraded to a Copy ?
1624     return NULL;                // No change
1625 
1626   Node *r = in(0);              // RegionNode
1627   assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1628 
1629   // Note: During parsing, phis are often transformed before their regions.
1630   // This means we have to use type_or_null to defend against untyped regions.
1631   if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1632     return NULL;                // No change
1633 
1634   Node *top = phase->C->top();
1635   bool new_phi = (outcnt() == 0); // transforming new Phi
1636   // No change for igvn if new phi is not hooked
1637   if (new_phi && can_reshape)
1638     return NULL;
1639 
1640   // The are 2 situations when only one valid phi's input is left
1641   // (in addition to Region input).
1642   // One: region is not loop - replace phi with this input.
1643   // Two: region is loop - replace phi with top since this data path is dead
1644   //                       and we need to break the dead data loop.
1645   Node* progress = NULL;        // Record if any progress made
1646   for( uint j = 1; j < req(); ++j ){ // For all paths in
1647     // Check unreachable control paths
1648     Node* rc = r->in(j);
1649     Node* n = in(j);            // Get the input
1650     if (rc == NULL || phase->type(rc) == Type::TOP) {
1651       if (n != top) {           // Not already top?
1652         PhaseIterGVN *igvn = phase->is_IterGVN();
1653         if (can_reshape && igvn != NULL) {
1654           igvn->_worklist.push(r);
1655         }
1656         set_req(j, top);        // Nuke it down
1657         progress = this;        // Record progress
1658       }
1659     }
1660   }
1661 
1662   if (can_reshape && outcnt() == 0) {
1663     // set_req() above may kill outputs if Phi is referenced
1664     // only by itself on the dead (top) control path.
1665     return top;
1666   }
1667 
1668   bool uncasted = false;
1669   Node* uin = unique_input(phase, false);
1670   if (uin == NULL && can_reshape) {
1671     uncasted = true;
1672     uin = unique_input(phase, true);
1673   }
1674   if (uin == top) {             // Simplest case: no alive inputs.
1675     if (can_reshape)            // IGVN transformation
1676       return top;
1677     else
1678       return NULL;              // Identity will return TOP
1679   } else if (uin != NULL) {
1680     // Only one not-NULL unique input path is left.
1681     // Determine if this input is backedge of a loop.
1682     // (Skip new phis which have no uses and dead regions).
1683     if (outcnt() > 0 && r->in(0) != NULL) {
1684       // First, take the short cut when we know it is a loop and
1685       // the EntryControl data path is dead.
1686       // Loop node may have only one input because entry path
1687       // is removed in PhaseIdealLoop::Dominators().
1688       assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1689       bool is_loop = (r->is_Loop() && r->req() == 3);
1690       // Then, check if there is a data loop when phi references itself directly
1691       // or through other data nodes.
1692       if (is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl)) ||
1693          !is_loop && is_unsafe_data_reference(uin)) {
1694         // Break this data loop to avoid creation of a dead loop.
1695         if (can_reshape) {
1696           return top;
1697         } else {
1698           // We can't return top if we are in Parse phase - cut inputs only
1699           // let Identity to handle the case.
1700           replace_edge(uin, top);
1701           return NULL;
1702         }
1703       }
1704     }
1705 
1706     if (uncasted) {
1707       // Add cast nodes between the phi to be removed and its unique input.
1708       // Wait until after parsing for the type information to propagate from the casts.
1709       assert(can_reshape, "Invalid during parsing");
1710       const Type* phi_type = bottom_type();
1711       assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type");
1712       // Add casts to carry the control dependency of the Phi that is
1713       // going away
1714       Node* cast = NULL;
1715       if (phi_type->isa_int()) {
1716         cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true);
1717       } else {
1718         const Type* uin_type = phase->type(uin);
1719         if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
1720           cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1721         } else {
1722           // Use a CastPP for a cast to not null and a CheckCastPP for
1723           // a cast to a new klass (and both if both null-ness and
1724           // klass change).
1725 
1726           // If the type of phi is not null but the type of uin may be
1727           // null, uin's type must be casted to not null
1728           if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
1729               uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
1730             cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true);
1731           }
1732 
1733           // If the type of phi and uin, both casted to not null,
1734           // differ the klass of uin must be (check)cast'ed to match
1735           // that of phi
1736           if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
1737             Node* n = uin;
1738             if (cast != NULL) {
1739               cast = phase->transform(cast);
1740               n = cast;
1741             }
1742             cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true);
1743           }
1744           if (cast == NULL) {
1745             cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1746           }
1747         }
1748       }
1749       assert(cast != NULL, "cast should be set");
1750       cast = phase->transform(cast);
1751       // set all inputs to the new cast(s) so the Phi is removed by Identity
1752       PhaseIterGVN* igvn = phase->is_IterGVN();
1753       for (uint i = 1; i < req(); i++) {
1754         set_req_X(i, cast, igvn);
1755       }
1756       uin = cast;
1757     }
1758 
1759     // One unique input.
1760     debug_only(Node* ident = Identity(phase));
1761     // The unique input must eventually be detected by the Identity call.
1762 #ifdef ASSERT
1763     if (ident != uin && !ident->is_top()) {
1764       // print this output before failing assert
1765       r->dump(3);
1766       this->dump(3);
1767       ident->dump();
1768       uin->dump();
1769     }
1770 #endif
1771     assert(ident == uin || ident->is_top(), "Identity must clean this up");
1772     return NULL;
1773   }
1774 
1775   Node* opt = NULL;
1776   int true_path = is_diamond_phi();
1777   if( true_path != 0 ) {
1778     // Check for CMove'ing identity. If it would be unsafe,
1779     // handle it here. In the safe case, let Identity handle it.
1780     Node* unsafe_id = is_cmove_id(phase, true_path);
1781     if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1782       opt = unsafe_id;
1783 
1784     // Check for simple convert-to-boolean pattern
1785     if( opt == NULL )
1786       opt = is_x2logic(phase, this, true_path);
1787 
1788     // Check for absolute value
1789     if( opt == NULL )
1790       opt = is_absolute(phase, this, true_path);
1791 
1792     // Check for conditional add
1793     if( opt == NULL && can_reshape )
1794       opt = is_cond_add(phase, this, true_path);
1795 
1796     // These 4 optimizations could subsume the phi:
1797     // have to check for a dead data loop creation.
1798     if( opt != NULL ) {
1799       if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1800         // Found dead loop.
1801         if( can_reshape )
1802           return top;
1803         // We can't return top if we are in Parse phase - cut inputs only
1804         // to stop further optimizations for this phi. Identity will return TOP.
1805         assert(req() == 3, "only diamond merge phi here");
1806         set_req(1, top);
1807         set_req(2, top);
1808         return NULL;
1809       } else {
1810         return opt;
1811       }
1812     }
1813   }
1814 
1815   // Check for merging identical values and split flow paths
1816   if (can_reshape) {
1817     opt = split_flow_path(phase, this);
1818     // This optimization only modifies phi - don't need to check for dead loop.
1819     assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1820     if (opt != NULL)  return opt;
1821   }
1822 
1823   if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1824     // Try to undo Phi of AddP:
1825     // (Phi (AddP base base y) (AddP base2 base2 y))
1826     // becomes:
1827     // newbase := (Phi base base2)
1828     // (AddP newbase newbase y)
1829     //
1830     // This occurs as a result of unsuccessful split_thru_phi and
1831     // interferes with taking advantage of addressing modes. See the
1832     // clone_shift_expressions code in matcher.cpp
1833     Node* addp = in(1);
1834     const Type* type = addp->in(AddPNode::Base)->bottom_type();
1835     Node* y = addp->in(AddPNode::Offset);
1836     if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
1837       // make sure that all the inputs are similar to the first one,
1838       // i.e. AddP with base == address and same offset as first AddP
1839       bool doit = true;
1840       for (uint i = 2; i < req(); i++) {
1841         if (in(i) == NULL ||
1842             in(i)->Opcode() != Op_AddP ||
1843             in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
1844             in(i)->in(AddPNode::Offset) != y) {
1845           doit = false;
1846           break;
1847         }
1848         // Accumulate type for resulting Phi
1849         type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
1850       }
1851       Node* base = NULL;
1852       if (doit) {
1853         // Check for neighboring AddP nodes in a tree.
1854         // If they have a base, use that it.
1855         for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
1856           Node* u = this->fast_out(k);
1857           if (u->is_AddP()) {
1858             Node* base2 = u->in(AddPNode::Base);
1859             if (base2 != NULL && !base2->is_top()) {
1860               if (base == NULL)
1861                 base = base2;
1862               else if (base != base2)
1863                 { doit = false; break; }
1864             }
1865           }
1866         }
1867       }
1868       if (doit) {
1869         if (base == NULL) {
1870           base = new PhiNode(in(0), type, NULL);
1871           for (uint i = 1; i < req(); i++) {
1872             base->init_req(i, in(i)->in(AddPNode::Base));
1873           }
1874           phase->is_IterGVN()->register_new_node_with_optimizer(base);
1875         }
1876         return new AddPNode(base, base, y);
1877       }
1878     }
1879   }
1880 
1881   // Split phis through memory merges, so that the memory merges will go away.
1882   // Piggy-back this transformation on the search for a unique input....
1883   // It will be as if the merged memory is the unique value of the phi.
1884   // (Do not attempt this optimization unless parsing is complete.
1885   // It would make the parser's memory-merge logic sick.)
1886   // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
1887   if (progress == NULL && can_reshape && type() == Type::MEMORY) {
1888     // see if this phi should be sliced
1889     uint merge_width = 0;
1890     bool saw_self = false;
1891     for( uint i=1; i<req(); ++i ) {// For all paths in
1892       Node *ii = in(i);
1893       // TOP inputs should not be counted as safe inputs because if the
1894       // Phi references itself through all other inputs then splitting the
1895       // Phi through memory merges would create dead loop at later stage.
1896       if (ii == top) {
1897         return NULL; // Delay optimization until graph is cleaned.
1898       }
1899       if (ii->is_MergeMem()) {
1900         MergeMemNode* n = ii->as_MergeMem();
1901         merge_width = MAX2(merge_width, n->req());
1902         saw_self = saw_self || phase->eqv(n->base_memory(), this);
1903       }
1904     }
1905 
1906     // This restriction is temporarily necessary to ensure termination:
1907     if (!saw_self && adr_type() == TypePtr::BOTTOM)  merge_width = 0;
1908 
1909     if (merge_width > Compile::AliasIdxRaw) {
1910       // found at least one non-empty MergeMem
1911       const TypePtr* at = adr_type();
1912       if (at != TypePtr::BOTTOM) {
1913         // Patch the existing phi to select an input from the merge:
1914         // Phi:AT1(...MergeMem(m0, m1, m2)...) into
1915         //     Phi:AT1(...m1...)
1916         int alias_idx = phase->C->get_alias_index(at);
1917         for (uint i=1; i<req(); ++i) {
1918           Node *ii = in(i);
1919           if (ii->is_MergeMem()) {
1920             MergeMemNode* n = ii->as_MergeMem();
1921             // compress paths and change unreachable cycles to TOP
1922             // If not, we can update the input infinitely along a MergeMem cycle
1923             // Equivalent code is in MemNode::Ideal_common
1924             Node *m  = phase->transform(n);
1925             if (outcnt() == 0) {  // Above transform() may kill us!
1926               return top;
1927             }
1928             // If transformed to a MergeMem, get the desired slice
1929             // Otherwise the returned node represents memory for every slice
1930             Node *new_mem = (m->is_MergeMem()) ?
1931                              m->as_MergeMem()->memory_at(alias_idx) : m;
1932             // Update input if it is progress over what we have now
1933             if (new_mem != ii) {
1934               set_req(i, new_mem);
1935               progress = this;
1936             }
1937           }
1938         }
1939       } else {
1940         // We know that at least one MergeMem->base_memory() == this
1941         // (saw_self == true). If all other inputs also references this phi
1942         // (directly or through data nodes) - it is dead loop.
1943         bool saw_safe_input = false;
1944         for (uint j = 1; j < req(); ++j) {
1945           Node *n = in(j);
1946           if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
1947             continue;              // skip known cases
1948           if (!is_unsafe_data_reference(n)) {
1949             saw_safe_input = true; // found safe input
1950             break;
1951           }
1952         }
1953         if (!saw_safe_input)
1954           return top; // all inputs reference back to this phi - dead loop
1955 
1956         // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
1957         //     MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
1958         PhaseIterGVN *igvn = phase->is_IterGVN();
1959         Node* hook = new Node(1);
1960         PhiNode* new_base = (PhiNode*) clone();
1961         // Must eagerly register phis, since they participate in loops.
1962         if (igvn) {
1963           igvn->register_new_node_with_optimizer(new_base);
1964           hook->add_req(new_base);
1965         }
1966         MergeMemNode* result = MergeMemNode::make(new_base);
1967         for (uint i = 1; i < req(); ++i) {
1968           Node *ii = in(i);
1969           if (ii->is_MergeMem()) {
1970             MergeMemNode* n = ii->as_MergeMem();
1971             for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
1972               // If we have not seen this slice yet, make a phi for it.
1973               bool made_new_phi = false;
1974               if (mms.is_empty()) {
1975                 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
1976                 made_new_phi = true;
1977                 if (igvn) {
1978                   igvn->register_new_node_with_optimizer(new_phi);
1979                   hook->add_req(new_phi);
1980                 }
1981                 mms.set_memory(new_phi);
1982               }
1983               Node* phi = mms.memory();
1984               assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
1985               phi->set_req(i, mms.memory2());
1986             }
1987           }
1988         }
1989         // Distribute all self-loops.
1990         { // (Extra braces to hide mms.)
1991           for (MergeMemStream mms(result); mms.next_non_empty(); ) {
1992             Node* phi = mms.memory();
1993             for (uint i = 1; i < req(); ++i) {
1994               if (phi->in(i) == this)  phi->set_req(i, phi);
1995             }
1996           }
1997         }
1998         // now transform the new nodes, and return the mergemem
1999         for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2000           Node* phi = mms.memory();
2001           mms.set_memory(phase->transform(phi));
2002         }
2003         if (igvn) { // Unhook.
2004           igvn->hash_delete(hook);
2005           for (uint i = 1; i < hook->req(); i++) {
2006             hook->set_req(i, NULL);
2007           }
2008         }
2009         // Replace self with the result.
2010         return result;
2011       }
2012     }
2013     //
2014     // Other optimizations on the memory chain
2015     //
2016     const TypePtr* at = adr_type();
2017     for( uint i=1; i<req(); ++i ) {// For all paths in
2018       Node *ii = in(i);
2019       Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2020       if (ii != new_in ) {
2021         set_req(i, new_in);
2022         progress = this;
2023       }
2024     }
2025   }
2026 
2027 #ifdef _LP64
2028   // Push DecodeN/DecodeNKlass down through phi.
2029   // The rest of phi graph will transform by split EncodeP node though phis up.
2030   if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2031     bool may_push = true;
2032     bool has_decodeN = false;
2033     bool is_decodeN = false;
2034     for (uint i=1; i<req(); ++i) {// For all paths in
2035       Node *ii = in(i);
2036       if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2037         // Do optimization if a non dead path exist.
2038         if (ii->in(1)->bottom_type() != Type::TOP) {
2039           has_decodeN = true;
2040           is_decodeN = ii->is_DecodeN();
2041         }
2042       } else if (!ii->is_Phi()) {
2043         may_push = false;
2044       }
2045     }
2046 
2047     if (has_decodeN && may_push) {
2048       PhaseIterGVN *igvn = phase->is_IterGVN();
2049       // Make narrow type for new phi.
2050       const Type* narrow_t;
2051       if (is_decodeN) {
2052         narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2053       } else {
2054         narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2055       }
2056       PhiNode* new_phi = new PhiNode(r, narrow_t);
2057       uint orig_cnt = req();
2058       for (uint i=1; i<req(); ++i) {// For all paths in
2059         Node *ii = in(i);
2060         Node* new_ii = NULL;
2061         if (ii->is_DecodeNarrowPtr()) {
2062           assert(ii->bottom_type() == bottom_type(), "sanity");
2063           new_ii = ii->in(1);
2064         } else {
2065           assert(ii->is_Phi(), "sanity");
2066           if (ii->as_Phi() == this) {
2067             new_ii = new_phi;
2068           } else {
2069             if (is_decodeN) {
2070               new_ii = new EncodePNode(ii, narrow_t);
2071             } else {
2072               new_ii = new EncodePKlassNode(ii, narrow_t);
2073             }
2074             igvn->register_new_node_with_optimizer(new_ii);
2075           }
2076         }
2077         new_phi->set_req(i, new_ii);
2078       }
2079       igvn->register_new_node_with_optimizer(new_phi, this);
2080       if (is_decodeN) {
2081         progress = new DecodeNNode(new_phi, bottom_type());
2082       } else {
2083         progress = new DecodeNKlassNode(new_phi, bottom_type());
2084       }
2085     }
2086   }
2087 #endif
2088 
2089   return progress;              // Return any progress
2090 }
2091 
2092 //------------------------------is_tripcount-----------------------------------
2093 bool PhiNode::is_tripcount() const {
2094   return (in(0) != NULL && in(0)->is_CountedLoop() &&
2095           in(0)->as_CountedLoop()->phi() == this);
2096 }
2097 
2098 //------------------------------out_RegMask------------------------------------
2099 const RegMask &PhiNode::in_RegMask(uint i) const {
2100   return i ? out_RegMask() : RegMask::Empty;
2101 }
2102 
2103 const RegMask &PhiNode::out_RegMask() const {
2104   uint ideal_reg = _type->ideal_reg();
2105   assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2106   if( ideal_reg == 0 ) return RegMask::Empty;
2107   assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2108   return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2109 }
2110 
2111 #ifndef PRODUCT
2112 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2113   // For a PhiNode, the set of related nodes includes all inputs till level 2,
2114   // and all outputs till level 1. In compact mode, inputs till level 1 are
2115   // collected.
2116   this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2117   this->collect_nodes(out_rel, -1, false, false);
2118 }
2119 
2120 void PhiNode::dump_spec(outputStream *st) const {
2121   TypeNode::dump_spec(st);
2122   if (is_tripcount()) {
2123     st->print(" #tripcount");
2124   }
2125 }
2126 #endif
2127 
2128 
2129 //=============================================================================
2130 const Type* GotoNode::Value(PhaseGVN* phase) const {
2131   // If the input is reachable, then we are executed.
2132   // If the input is not reachable, then we are not executed.
2133   return phase->type(in(0));
2134 }
2135 
2136 Node* GotoNode::Identity(PhaseGVN* phase) {
2137   return in(0);                // Simple copy of incoming control
2138 }
2139 
2140 const RegMask &GotoNode::out_RegMask() const {
2141   return RegMask::Empty;
2142 }
2143 
2144 #ifndef PRODUCT
2145 //-----------------------------related-----------------------------------------
2146 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2147 // outputs at level 1. This is regardless of compact mode.
2148 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2149   this->collect_nodes(in_rel, 1, false, false);
2150   this->collect_nodes(out_rel, -1, false, false);
2151 }
2152 #endif
2153 
2154 
2155 //=============================================================================
2156 const RegMask &JumpNode::out_RegMask() const {
2157   return RegMask::Empty;
2158 }
2159 
2160 #ifndef PRODUCT
2161 //-----------------------------related-----------------------------------------
2162 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2163 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2164 // This is regardless of compact mode.
2165 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2166   this->collect_nodes(in_rel, 1, false, false);
2167   this->collect_nodes(out_rel, -2, false, false);
2168 }
2169 #endif
2170 
2171 //=============================================================================
2172 const RegMask &JProjNode::out_RegMask() const {
2173   return RegMask::Empty;
2174 }
2175 
2176 //=============================================================================
2177 const RegMask &CProjNode::out_RegMask() const {
2178   return RegMask::Empty;
2179 }
2180 
2181 
2182 
2183 //=============================================================================
2184 
2185 uint PCTableNode::hash() const { return Node::hash() + _size; }
2186 uint PCTableNode::cmp( const Node &n ) const
2187 { return _size == ((PCTableNode&)n)._size; }
2188 
2189 const Type *PCTableNode::bottom_type() const {
2190   const Type** f = TypeTuple::fields(_size);
2191   for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2192   return TypeTuple::make(_size, f);
2193 }
2194 
2195 //------------------------------Value------------------------------------------
2196 // Compute the type of the PCTableNode.  If reachable it is a tuple of
2197 // Control, otherwise the table targets are not reachable
2198 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2199   if( phase->type(in(0)) == Type::CONTROL )
2200     return bottom_type();
2201   return Type::TOP;             // All paths dead?  Then so are we
2202 }
2203 
2204 //------------------------------Ideal------------------------------------------
2205 // Return a node which is more "ideal" than the current node.  Strip out
2206 // control copies
2207 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2208   return remove_dead_region(phase, can_reshape) ? this : NULL;
2209 }
2210 
2211 //=============================================================================
2212 uint JumpProjNode::hash() const {
2213   return Node::hash() + _dest_bci;
2214 }
2215 
2216 uint JumpProjNode::cmp( const Node &n ) const {
2217   return ProjNode::cmp(n) &&
2218     _dest_bci == ((JumpProjNode&)n)._dest_bci;
2219 }
2220 
2221 #ifndef PRODUCT
2222 void JumpProjNode::dump_spec(outputStream *st) const {
2223   ProjNode::dump_spec(st);
2224   st->print("@bci %d ",_dest_bci);
2225 }
2226 
2227 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2228   ProjNode::dump_compact_spec(st);
2229   st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2230 }
2231 
2232 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2233   // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2234   this->collect_nodes(in_rel, 1, false, false);
2235   this->collect_nodes(out_rel, -1, false, false);
2236 }
2237 #endif
2238 
2239 //=============================================================================
2240 //------------------------------Value------------------------------------------
2241 // Check for being unreachable, or for coming from a Rethrow.  Rethrow's cannot
2242 // have the default "fall_through_index" path.
2243 const Type* CatchNode::Value(PhaseGVN* phase) const {
2244   // Unreachable?  Then so are all paths from here.
2245   if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2246   // First assume all paths are reachable
2247   const Type** f = TypeTuple::fields(_size);
2248   for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2249   // Identify cases that will always throw an exception
2250   // () rethrow call
2251   // () virtual or interface call with NULL receiver
2252   // () call is a check cast with incompatible arguments
2253   if( in(1)->is_Proj() ) {
2254     Node *i10 = in(1)->in(0);
2255     if( i10->is_Call() ) {
2256       CallNode *call = i10->as_Call();
2257       // Rethrows always throw exceptions, never return
2258       if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2259         f[CatchProjNode::fall_through_index] = Type::TOP;
2260       } else if( call->req() > TypeFunc::Parms ) {
2261         const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2262         // Check for null receiver to virtual or interface calls
2263         if( call->is_CallDynamicJava() &&
2264             arg0->higher_equal(TypePtr::NULL_PTR) ) {
2265           f[CatchProjNode::fall_through_index] = Type::TOP;
2266         }
2267       } // End of if not a runtime stub
2268     } // End of if have call above me
2269   } // End of slot 1 is not a projection
2270   return TypeTuple::make(_size, f);
2271 }
2272 
2273 //=============================================================================
2274 uint CatchProjNode::hash() const {
2275   return Node::hash() + _handler_bci;
2276 }
2277 
2278 
2279 uint CatchProjNode::cmp( const Node &n ) const {
2280   return ProjNode::cmp(n) &&
2281     _handler_bci == ((CatchProjNode&)n)._handler_bci;
2282 }
2283 
2284 
2285 //------------------------------Identity---------------------------------------
2286 // If only 1 target is possible, choose it if it is the main control
2287 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2288   // If my value is control and no other value is, then treat as ID
2289   const TypeTuple *t = phase->type(in(0))->is_tuple();
2290   if (t->field_at(_con) != Type::CONTROL)  return this;
2291   // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2292   // also remove any exception table entry.  Thus we must know the call
2293   // feeding the Catch will not really throw an exception.  This is ok for
2294   // the main fall-thru control (happens when we know a call can never throw
2295   // an exception) or for "rethrow", because a further optimization will
2296   // yank the rethrow (happens when we inline a function that can throw an
2297   // exception and the caller has no handler).  Not legal, e.g., for passing
2298   // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2299   // These cases MUST throw an exception via the runtime system, so the VM
2300   // will be looking for a table entry.
2301   Node *proj = in(0)->in(1);    // Expect a proj feeding CatchNode
2302   CallNode *call;
2303   if (_con != TypeFunc::Control && // Bail out if not the main control.
2304       !(proj->is_Proj() &&      // AND NOT a rethrow
2305         proj->in(0)->is_Call() &&
2306         (call = proj->in(0)->as_Call()) &&
2307         call->entry_point() == OptoRuntime::rethrow_stub()))
2308     return this;
2309 
2310   // Search for any other path being control
2311   for (uint i = 0; i < t->cnt(); i++) {
2312     if (i != _con && t->field_at(i) == Type::CONTROL)
2313       return this;
2314   }
2315   // Only my path is possible; I am identity on control to the jump
2316   return in(0)->in(0);
2317 }
2318 
2319 
2320 #ifndef PRODUCT
2321 void CatchProjNode::dump_spec(outputStream *st) const {
2322   ProjNode::dump_spec(st);
2323   st->print("@bci %d ",_handler_bci);
2324 }
2325 #endif
2326 
2327 //=============================================================================
2328 //------------------------------Identity---------------------------------------
2329 // Check for CreateEx being Identity.
2330 Node* CreateExNode::Identity(PhaseGVN* phase) {
2331   if( phase->type(in(1)) == Type::TOP ) return in(1);
2332   if( phase->type(in(0)) == Type::TOP ) return in(0);
2333   // We only come from CatchProj, unless the CatchProj goes away.
2334   // If the CatchProj is optimized away, then we just carry the
2335   // exception oop through.
2336   CallNode *call = in(1)->in(0)->as_Call();
2337 
2338   return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2339     ? this
2340     : call->in(TypeFunc::Parms);
2341 }
2342 
2343 //=============================================================================
2344 //------------------------------Value------------------------------------------
2345 // Check for being unreachable.
2346 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2347   if (!in(0) || in(0)->is_top()) return Type::TOP;
2348   return bottom_type();
2349 }
2350 
2351 //------------------------------Ideal------------------------------------------
2352 // Check for no longer being part of a loop
2353 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2354   if (can_reshape && !in(0)->is_Loop()) {
2355     // Dead code elimination can sometimes delete this projection so
2356     // if it's not there, there's nothing to do.
2357     Node* fallthru = proj_out(0);
2358     if (fallthru != NULL) {
2359       phase->is_IterGVN()->replace_node(fallthru, in(0));
2360     }
2361     return phase->C->top();
2362   }
2363   return NULL;
2364 }
2365 
2366 #ifndef PRODUCT
2367 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2368   st->print("%s", Name());
2369 }
2370 #endif