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