1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/systemDictionary.hpp"
  27 #include "memory/allocation.inline.hpp"
  28 #include "memory/resourceArea.hpp"
  29 #include "oops/objArrayKlass.hpp"
  30 #include "opto/addnode.hpp"
  31 #include "opto/castnode.hpp"
  32 #include "opto/cfgnode.hpp"
  33 #include "opto/connode.hpp"
  34 #include "opto/convertnode.hpp"
  35 #include "opto/loopnode.hpp"
  36 #include "opto/machnode.hpp"
  37 #include "opto/movenode.hpp"
  38 #include "opto/narrowptrnode.hpp"
  39 #include "opto/mulnode.hpp"
  40 #include "opto/phaseX.hpp"
  41 #include "opto/regmask.hpp"
  42 #include "opto/runtime.hpp"
  43 #include "opto/subnode.hpp"
  44 #include "utilities/vmError.hpp"
  45 
  46 // Portions of code courtesy of Clifford Click
  47 
  48 // Optimization - Graph Style
  49 
  50 //=============================================================================
  51 //------------------------------Value------------------------------------------
  52 // Compute the type of the RegionNode.
  53 const Type* RegionNode::Value(PhaseGVN* phase) const {
  54   for( uint i=1; i<req(); ++i ) {       // For all paths in
  55     Node *n = in(i);            // Get Control source
  56     if( !n ) continue;          // Missing inputs are TOP
  57     if( phase->type(n) == Type::CONTROL )
  58       return Type::CONTROL;
  59   }
  60   return Type::TOP;             // All paths dead?  Then so are we
  61 }
  62 
  63 //------------------------------Identity---------------------------------------
  64 // Check for Region being Identity.
  65 Node* RegionNode::Identity(PhaseGVN* phase) {
  66   // Cannot have Region be an identity, even if it has only 1 input.
  67   // Phi users cannot have their Region input folded away for them,
  68   // since they need to select the proper data input
  69   return this;
  70 }
  71 
  72 //------------------------------merge_region-----------------------------------
  73 // If a Region flows into a Region, merge into one big happy merge.  This is
  74 // hard to do if there is stuff that has to happen
  75 static Node *merge_region(RegionNode *region, PhaseGVN *phase) {
  76   if( region->Opcode() != Op_Region ) // Do not do to LoopNodes
  77     return NULL;
  78   Node *progress = NULL;        // Progress flag
  79   PhaseIterGVN *igvn = phase->is_IterGVN();
  80 
  81   uint rreq = region->req();
  82   for( uint i = 1; i < rreq; i++ ) {
  83     Node *r = region->in(i);
  84     if( r && r->Opcode() == Op_Region && // Found a region?
  85         r->in(0) == r &&        // Not already collapsed?
  86         r != region &&          // Avoid stupid situations
  87         r->outcnt() == 2 ) {    // Self user and 'region' user only?
  88       assert(!r->as_Region()->has_phi(), "no phi users");
  89       if( !progress ) {         // No progress
  90         if (region->has_phi()) {
  91           return NULL;        // Only flatten if no Phi users
  92           // igvn->hash_delete( phi );
  93         }
  94         igvn->hash_delete( region );
  95         progress = region;      // Making progress
  96       }
  97       igvn->hash_delete( r );
  98 
  99       // Append inputs to 'r' onto 'region'
 100       for( uint j = 1; j < r->req(); j++ ) {
 101         // Move an input from 'r' to 'region'
 102         region->add_req(r->in(j));
 103         r->set_req(j, phase->C->top());
 104         // Update phis of 'region'
 105         //for( uint k = 0; k < max; k++ ) {
 106         //  Node *phi = region->out(k);
 107         //  if( phi->is_Phi() ) {
 108         //    phi->add_req(phi->in(i));
 109         //  }
 110         //}
 111 
 112         rreq++;                 // One more input to Region
 113       } // Found a region to merge into Region
 114       igvn->_worklist.push(r);
 115       // Clobber pointer to the now dead 'r'
 116       region->set_req(i, phase->C->top());
 117     }
 118   }
 119 
 120   return progress;
 121 }
 122 
 123 
 124 
 125 //--------------------------------has_phi--------------------------------------
 126 // Helper function: Return any PhiNode that uses this region or NULL
 127 PhiNode* RegionNode::has_phi() const {
 128   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 129     Node* phi = fast_out(i);
 130     if (phi->is_Phi()) {   // Check for Phi users
 131       assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
 132       return phi->as_Phi();  // this one is good enough
 133     }
 134   }
 135 
 136   return NULL;
 137 }
 138 
 139 
 140 //-----------------------------has_unique_phi----------------------------------
 141 // Helper function: Return the only PhiNode that uses this region or NULL
 142 PhiNode* RegionNode::has_unique_phi() const {
 143   // Check that only one use is a Phi
 144   PhiNode* only_phi = NULL;
 145   for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
 146     Node* phi = fast_out(i);
 147     if (phi->is_Phi()) {   // Check for Phi users
 148       assert(phi->in(0) == (Node*)this, "phi uses region only via in(0)");
 149       if (only_phi == NULL) {
 150         only_phi = phi->as_Phi();
 151       } else {
 152         return NULL;  // multiple phis
 153       }
 154     }
 155   }
 156 
 157   return only_phi;
 158 }
 159 
 160 
 161 //------------------------------check_phi_clipping-----------------------------
 162 // Helper function for RegionNode's identification of FP clipping
 163 // Check inputs to the Phi
 164 static bool check_phi_clipping( PhiNode *phi, ConNode * &min, uint &min_idx, ConNode * &max, uint &max_idx, Node * &val, uint &val_idx ) {
 165   min     = NULL;
 166   max     = NULL;
 167   val     = NULL;
 168   min_idx = 0;
 169   max_idx = 0;
 170   val_idx = 0;
 171   uint  phi_max = phi->req();
 172   if( phi_max == 4 ) {
 173     for( uint j = 1; j < phi_max; ++j ) {
 174       Node *n = phi->in(j);
 175       int opcode = n->Opcode();
 176       switch( opcode ) {
 177       case Op_ConI:
 178         {
 179           if( min == NULL ) {
 180             min     = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
 181             min_idx = j;
 182           } else {
 183             max     = n->Opcode() == Op_ConI ? (ConNode*)n : NULL;
 184             max_idx = j;
 185             if( min->get_int() > max->get_int() ) {
 186               // Swap min and max
 187               ConNode *temp;
 188               uint     temp_idx;
 189               temp     = min;     min     = max;     max     = temp;
 190               temp_idx = min_idx; min_idx = max_idx; max_idx = temp_idx;
 191             }
 192           }
 193         }
 194         break;
 195       default:
 196         {
 197           val = n;
 198           val_idx = j;
 199         }
 200         break;
 201       }
 202     }
 203   }
 204   return ( min && max && val && (min->get_int() <= 0) && (max->get_int() >=0) );
 205 }
 206 
 207 
 208 //------------------------------check_if_clipping------------------------------
 209 // Helper function for RegionNode's identification of FP clipping
 210 // Check that inputs to Region come from two IfNodes,
 211 //
 212 //            If
 213 //      False    True
 214 //       If        |
 215 //  False  True    |
 216 //    |      |     |
 217 //  RegionNode_inputs
 218 //
 219 static bool check_if_clipping( const RegionNode *region, IfNode * &bot_if, IfNode * &top_if ) {
 220   top_if = NULL;
 221   bot_if = NULL;
 222 
 223   // Check control structure above RegionNode for (if  ( if  ) )
 224   Node *in1 = region->in(1);
 225   Node *in2 = region->in(2);
 226   Node *in3 = region->in(3);
 227   // Check that all inputs are projections
 228   if( in1->is_Proj() && in2->is_Proj() && in3->is_Proj() ) {
 229     Node *in10 = in1->in(0);
 230     Node *in20 = in2->in(0);
 231     Node *in30 = in3->in(0);
 232     // Check that #1 and #2 are ifTrue and ifFalse from same If
 233     if( in10 != NULL && in10->is_If() &&
 234         in20 != NULL && in20->is_If() &&
 235         in30 != NULL && in30->is_If() && in10 == in20 &&
 236         (in1->Opcode() != in2->Opcode()) ) {
 237       Node  *in100 = in10->in(0);
 238       Node *in1000 = (in100 != NULL && in100->is_Proj()) ? in100->in(0) : NULL;
 239       // Check that control for in10 comes from other branch of IF from in3
 240       if( in1000 != NULL && in1000->is_If() &&
 241           in30 == in1000 && (in3->Opcode() != in100->Opcode()) ) {
 242         // Control pattern checks
 243         top_if = (IfNode*)in1000;
 244         bot_if = (IfNode*)in10;
 245       }
 246     }
 247   }
 248 
 249   return (top_if != NULL);
 250 }
 251 
 252 
 253 //------------------------------check_convf2i_clipping-------------------------
 254 // Helper function for RegionNode's identification of FP clipping
 255 // Verify that the value input to the phi comes from "ConvF2I; LShift; RShift"
 256 static bool check_convf2i_clipping( PhiNode *phi, uint idx, ConvF2INode * &convf2i, Node *min, Node *max) {
 257   convf2i = NULL;
 258 
 259   // Check for the RShiftNode
 260   Node *rshift = phi->in(idx);
 261   assert( rshift, "Previous checks ensure phi input is present");
 262   if( rshift->Opcode() != Op_RShiftI )  { return false; }
 263 
 264   // Check for the LShiftNode
 265   Node *lshift = rshift->in(1);
 266   assert( lshift, "Previous checks ensure phi input is present");
 267   if( lshift->Opcode() != Op_LShiftI )  { return false; }
 268 
 269   // Check for the ConvF2INode
 270   Node *conv = lshift->in(1);
 271   if( conv->Opcode() != Op_ConvF2I ) { return false; }
 272 
 273   // Check that shift amounts are only to get sign bits set after F2I
 274   jint max_cutoff     = max->get_int();
 275   jint min_cutoff     = min->get_int();
 276   jint left_shift     = lshift->in(2)->get_int();
 277   jint right_shift    = rshift->in(2)->get_int();
 278   jint max_post_shift = nth_bit(BitsPerJavaInteger - left_shift - 1);
 279   if( left_shift != right_shift ||
 280       0 > left_shift || left_shift >= BitsPerJavaInteger ||
 281       max_post_shift < max_cutoff ||
 282       max_post_shift < -min_cutoff ) {
 283     // Shifts are necessary but current transformation eliminates them
 284     return false;
 285   }
 286 
 287   // OK to return the result of ConvF2I without shifting
 288   convf2i = (ConvF2INode*)conv;
 289   return true;
 290 }
 291 
 292 
 293 //------------------------------check_compare_clipping-------------------------
 294 // Helper function for RegionNode's identification of FP clipping
 295 static bool check_compare_clipping( bool less_than, IfNode *iff, ConNode *limit, Node * & input ) {
 296   Node *i1 = iff->in(1);
 297   if ( !i1->is_Bool() ) { return false; }
 298   BoolNode *bool1 = i1->as_Bool();
 299   if(       less_than && bool1->_test._test != BoolTest::le ) { return false; }
 300   else if( !less_than && bool1->_test._test != BoolTest::lt ) { return false; }
 301   const Node *cmpF = bool1->in(1);
 302   if( cmpF->Opcode() != Op_CmpF )      { return false; }
 303   // Test that the float value being compared against
 304   // is equivalent to the int value used as a limit
 305   Node *nodef = cmpF->in(2);
 306   if( nodef->Opcode() != Op_ConF ) { return false; }
 307   jfloat conf = nodef->getf();
 308   jint   coni = limit->get_int();
 309   if( ((int)conf) != coni )        { return false; }
 310   input = cmpF->in(1);
 311   return true;
 312 }
 313 
 314 //------------------------------is_unreachable_region--------------------------
 315 // Find if the Region node is reachable from the root.
 316 bool RegionNode::is_unreachable_region(PhaseGVN *phase) const {
 317   assert(req() == 2, "");
 318 
 319   // First, cut the simple case of fallthrough region when NONE of
 320   // region's phis references itself directly or through a data node.
 321   uint max = outcnt();
 322   uint i;
 323   for (i = 0; i < max; i++) {
 324     Node* phi = raw_out(i);
 325     if (phi != NULL && phi->is_Phi()) {
 326       assert(phase->eqv(phi->in(0), this) && phi->req() == 2, "");
 327       if (phi->outcnt() == 0)
 328         continue; // Safe case - no loops
 329       if (phi->outcnt() == 1) {
 330         Node* u = phi->raw_out(0);
 331         // Skip if only one use is an other Phi or Call or Uncommon trap.
 332         // It is safe to consider this case as fallthrough.
 333         if (u != NULL && (u->is_Phi() || u->is_CFG()))
 334           continue;
 335       }
 336       // Check when phi references itself directly or through an other node.
 337       if (phi->as_Phi()->simple_data_loop_check(phi->in(1)) >= PhiNode::Unsafe)
 338         break; // Found possible unsafe data loop.
 339     }
 340   }
 341   if (i >= max)
 342     return false; // An unsafe case was NOT found - don't need graph walk.
 343 
 344   // Unsafe case - check if the Region node is reachable from root.
 345   ResourceMark rm;
 346 
 347   Arena *a = Thread::current()->resource_area();
 348   Node_List nstack(a);
 349   VectorSet visited(a);
 350 
 351   // Mark all control nodes reachable from root outputs
 352   Node *n = (Node*)phase->C->root();
 353   nstack.push(n);
 354   visited.set(n->_idx);
 355   while (nstack.size() != 0) {
 356     n = nstack.pop();
 357     uint max = n->outcnt();
 358     for (uint i = 0; i < max; i++) {
 359       Node* m = n->raw_out(i);
 360       if (m != NULL && m->is_CFG()) {
 361         if (phase->eqv(m, this)) {
 362           return false; // We reached the Region node - it is not dead.
 363         }
 364         if (!visited.test_set(m->_idx))
 365           nstack.push(m);
 366       }
 367     }
 368   }
 369 
 370   return true; // The Region node is unreachable - it is dead.
 371 }
 372 
 373 bool RegionNode::try_clean_mem_phi(PhaseGVN *phase) {
 374   // Incremental inlining + PhaseStringOpts sometimes produce:
 375   //
 376   // cmpP with 1 top input
 377   //           |
 378   //          If
 379   //         /  \
 380   //   IfFalse  IfTrue  /- Some Node
 381   //         \  /      /    /
 382   //        Region    / /-MergeMem
 383   //             \---Phi
 384   //
 385   //
 386   // It's expected by PhaseStringOpts that the Region goes away and is
 387   // replaced by If's control input but because there's still a Phi,
 388   // the Region stays in the graph. The top input from the cmpP is
 389   // propagated forward and a subgraph that is useful goes away. The
 390   // code below replaces the Phi with the MergeMem so that the Region
 391   // is simplified.
 392 
 393   PhiNode* phi = has_unique_phi();
 394   if (phi && phi->type() == Type::MEMORY && req() == 3 && phi->is_diamond_phi(true)) {
 395     MergeMemNode* m = NULL;
 396     assert(phi->req() == 3, "same as region");
 397     for (uint i = 1; i < 3; ++i) {
 398       Node *mem = phi->in(i);
 399       if (mem && mem->is_MergeMem() && in(i)->outcnt() == 1) {
 400         // Nothing is control-dependent on path #i except the region itself.
 401         m = mem->as_MergeMem();
 402         uint j = 3 - i;
 403         Node* other = phi->in(j);
 404         if (other && other == m->base_memory()) {
 405           // m is a successor memory to other, and is not pinned inside the diamond, so push it out.
 406           // This will allow the diamond to collapse completely.
 407           phase->is_IterGVN()->replace_node(phi, m);
 408           return true;
 409         }
 410       }
 411     }
 412   }
 413   return false;
 414 }
 415 
 416 //------------------------------Ideal------------------------------------------
 417 // Return a node which is more "ideal" than the current node.  Must preserve
 418 // the CFG, but we can still strip out dead paths.
 419 Node *RegionNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 420   if( !can_reshape && !in(0) ) return NULL;     // Already degraded to a Copy
 421   assert(!in(0) || !in(0)->is_Root(), "not a specially hidden merge");
 422 
 423   // Check for RegionNode with no Phi users and both inputs come from either
 424   // arm of the same IF.  If found, then the control-flow split is useless.
 425   bool has_phis = false;
 426   if (can_reshape) {            // Need DU info to check for Phi users
 427     has_phis = (has_phi() != NULL);       // Cache result
 428     if (has_phis && try_clean_mem_phi(phase)) {
 429       has_phis = false;
 430     }
 431 
 432     if (!has_phis) {            // No Phi users?  Nothing merging?
 433       for (uint i = 1; i < req()-1; i++) {
 434         Node *if1 = in(i);
 435         if( !if1 ) continue;
 436         Node *iff = if1->in(0);
 437         if( !iff || !iff->is_If() ) continue;
 438         for( uint j=i+1; j<req(); j++ ) {
 439           if( in(j) && in(j)->in(0) == iff &&
 440               if1->Opcode() != in(j)->Opcode() ) {
 441             // Add the IF Projections to the worklist. They (and the IF itself)
 442             // will be eliminated if dead.
 443             phase->is_IterGVN()->add_users_to_worklist(iff);
 444             set_req(i, iff->in(0));// Skip around the useless IF diamond
 445             set_req(j, NULL);
 446             return this;      // Record progress
 447           }
 448         }
 449       }
 450     }
 451   }
 452 
 453   // Remove TOP or NULL input paths. If only 1 input path remains, this Region
 454   // degrades to a copy.
 455   bool add_to_worklist = false;
 456   bool modified = false;
 457   int cnt = 0;                  // Count of values merging
 458   DEBUG_ONLY( int cnt_orig = req(); ) // Save original inputs count
 459   int del_it = 0;               // The last input path we delete
 460   // For all inputs...
 461   for( uint i=1; i<req(); ++i ){// For all paths in
 462     Node *n = in(i);            // Get the input
 463     if( n != NULL ) {
 464       // Remove useless control copy inputs
 465       if( n->is_Region() && n->as_Region()->is_copy() ) {
 466         set_req(i, n->nonnull_req());
 467         modified = true;
 468         i--;
 469         continue;
 470       }
 471       if( n->is_Proj() ) {      // Remove useless rethrows
 472         Node *call = n->in(0);
 473         if (call->is_Call() && call->as_Call()->entry_point() == OptoRuntime::rethrow_stub()) {
 474           set_req(i, call->in(0));
 475           modified = true;
 476           i--;
 477           continue;
 478         }
 479       }
 480       if( phase->type(n) == Type::TOP ) {
 481         set_req(i, NULL);       // Ignore TOP inputs
 482         modified = true;
 483         i--;
 484         continue;
 485       }
 486       cnt++;                    // One more value merging
 487 
 488     } else if (can_reshape) {   // Else found dead path with DU info
 489       PhaseIterGVN *igvn = phase->is_IterGVN();
 490       del_req(i);               // Yank path from self
 491       del_it = i;
 492       uint max = outcnt();
 493       DUIterator j;
 494       bool progress = true;
 495       while(progress) {         // Need to establish property over all users
 496         progress = false;
 497         for (j = outs(); has_out(j); j++) {
 498           Node *n = out(j);
 499           if( n->req() != req() && n->is_Phi() ) {
 500             assert( n->in(0) == this, "" );
 501             igvn->hash_delete(n); // Yank from hash before hacking edges
 502             n->set_req_X(i,NULL,igvn);// Correct DU info
 503             n->del_req(i);        // Yank path from Phis
 504             if( max != outcnt() ) {
 505               progress = true;
 506               j = refresh_out_pos(j);
 507               max = outcnt();
 508             }
 509           }
 510         }
 511       }
 512       add_to_worklist = true;
 513       i--;
 514     }
 515   }
 516 
 517   if (can_reshape && cnt == 1) {
 518     // Is it dead loop?
 519     // If it is LoopNopde it had 2 (+1 itself) inputs and
 520     // one of them was cut. The loop is dead if it was EntryContol.
 521     // Loop node may have only one input because entry path
 522     // is removed in PhaseIdealLoop::Dominators().
 523     assert(!this->is_Loop() || cnt_orig <= 3, "Loop node should have 3 or less inputs");
 524     if ((this->is_Loop() && (del_it == LoopNode::EntryControl ||
 525                              (del_it == 0 && is_unreachable_region(phase)))) ||
 526         (!this->is_Loop() && has_phis && is_unreachable_region(phase))) {
 527       // Yes,  the region will be removed during the next step below.
 528       // Cut the backedge input and remove phis since no data paths left.
 529       // We don't cut outputs to other nodes here since we need to put them
 530       // on the worklist.
 531       PhaseIterGVN *igvn = phase->is_IterGVN();
 532       if (in(1)->outcnt() == 1) {
 533         igvn->_worklist.push(in(1));
 534       }
 535       del_req(1);
 536       cnt = 0;
 537       assert( req() == 1, "no more inputs expected" );
 538       uint max = outcnt();
 539       bool progress = true;
 540       Node *top = phase->C->top();
 541       DUIterator j;
 542       while(progress) {
 543         progress = false;
 544         for (j = outs(); has_out(j); j++) {
 545           Node *n = out(j);
 546           if( n->is_Phi() ) {
 547             assert( igvn->eqv(n->in(0), this), "" );
 548             assert( n->req() == 2 &&  n->in(1) != NULL, "Only one data input expected" );
 549             // Break dead loop data path.
 550             // Eagerly replace phis with top to avoid phis copies generation.
 551             igvn->replace_node(n, top);
 552             if( max != outcnt() ) {
 553               progress = true;
 554               j = refresh_out_pos(j);
 555               max = outcnt();
 556             }
 557           }
 558         }
 559       }
 560       add_to_worklist = true;
 561     }
 562   }
 563   if (add_to_worklist) {
 564     phase->is_IterGVN()->add_users_to_worklist(this); // Revisit collapsed Phis
 565   }
 566 
 567   if( cnt <= 1 ) {              // Only 1 path in?
 568     set_req(0, NULL);           // Null control input for region copy
 569     if( cnt == 0 && !can_reshape) { // Parse phase - leave the node as it is.
 570       // No inputs or all inputs are NULL.
 571       return NULL;
 572     } else if (can_reshape) {   // Optimization phase - remove the node
 573       PhaseIterGVN *igvn = phase->is_IterGVN();
 574       // Strip mined (inner) loop is going away, remove outer loop.
 575       if (is_CountedLoop() &&
 576           as_Loop()->is_strip_mined()) {
 577         Node* outer_sfpt = as_CountedLoop()->outer_safepoint();
 578         Node* outer_out = as_CountedLoop()->outer_loop_exit();
 579         if (outer_sfpt != NULL && outer_out != NULL) {
 580           Node* in = outer_sfpt->in(0);
 581           igvn->replace_node(outer_out, in);
 582           LoopNode* outer = as_CountedLoop()->outer_loop();
 583           igvn->replace_input_of(outer, LoopNode::LoopBackControl, igvn->C->top());
 584         }
 585       }
 586       Node *parent_ctrl;
 587       if( cnt == 0 ) {
 588         assert( req() == 1, "no inputs expected" );
 589         // During IGVN phase such region will be subsumed by TOP node
 590         // so region's phis will have TOP as control node.
 591         // Kill phis here to avoid it. PhiNode::is_copy() will be always false.
 592         // Also set other user's input to top.
 593         parent_ctrl = phase->C->top();
 594       } else {
 595         // The fallthrough case since we already checked dead loops above.
 596         parent_ctrl = in(1);
 597         assert(parent_ctrl != NULL, "Region is a copy of some non-null control");
 598         assert(!igvn->eqv(parent_ctrl, this), "Close dead loop");
 599       }
 600       if (!add_to_worklist)
 601         igvn->add_users_to_worklist(this); // Check for further allowed opts
 602       for (DUIterator_Last imin, i = last_outs(imin); i >= imin; --i) {
 603         Node* n = last_out(i);
 604         igvn->hash_delete(n); // Remove from worklist before modifying edges
 605         if( n->is_Phi() ) {   // Collapse all Phis
 606           // Eagerly replace phis to avoid copies generation.
 607           Node* in;
 608           if( cnt == 0 ) {
 609             assert( n->req() == 1, "No data inputs expected" );
 610             in = parent_ctrl; // replaced by top
 611           } else {
 612             assert( n->req() == 2 &&  n->in(1) != NULL, "Only one data input expected" );
 613             in = n->in(1);               // replaced by unique input
 614             if( n->as_Phi()->is_unsafe_data_reference(in) )
 615               in = phase->C->top();      // replaced by top
 616           }
 617           igvn->replace_node(n, in);
 618         }
 619         else if( n->is_Region() ) { // Update all incoming edges
 620           assert( !igvn->eqv(n, this), "Must be removed from DefUse edges");
 621           uint uses_found = 0;
 622           for( uint k=1; k < n->req(); k++ ) {
 623             if( n->in(k) == this ) {
 624               n->set_req(k, parent_ctrl);
 625               uses_found++;
 626             }
 627           }
 628           if( uses_found > 1 ) { // (--i) done at the end of the loop.
 629             i -= (uses_found - 1);
 630           }
 631         }
 632         else {
 633           assert( igvn->eqv(n->in(0), this), "Expect RegionNode to be control parent");
 634           n->set_req(0, parent_ctrl);
 635         }
 636 #ifdef ASSERT
 637         for( uint k=0; k < n->req(); k++ ) {
 638           assert( !igvn->eqv(n->in(k), this), "All uses of RegionNode should be gone");
 639         }
 640 #endif
 641       }
 642       // Remove the RegionNode itself from DefUse info
 643       igvn->remove_dead_node(this);
 644       return NULL;
 645     }
 646     return this;                // Record progress
 647   }
 648 
 649 
 650   // If a Region flows into a Region, merge into one big happy merge.
 651   if (can_reshape) {
 652     Node *m = merge_region(this, phase);
 653     if (m != NULL)  return m;
 654   }
 655 
 656   // Check if this region is the root of a clipping idiom on floats
 657   if( ConvertFloat2IntClipping && can_reshape && req() == 4 ) {
 658     // Check that only one use is a Phi and that it simplifies to two constants +
 659     PhiNode* phi = has_unique_phi();
 660     if (phi != NULL) {          // One Phi user
 661       // Check inputs to the Phi
 662       ConNode *min;
 663       ConNode *max;
 664       Node    *val;
 665       uint     min_idx;
 666       uint     max_idx;
 667       uint     val_idx;
 668       if( check_phi_clipping( phi, min, min_idx, max, max_idx, val, val_idx )  ) {
 669         IfNode *top_if;
 670         IfNode *bot_if;
 671         if( check_if_clipping( this, bot_if, top_if ) ) {
 672           // Control pattern checks, now verify compares
 673           Node   *top_in = NULL;   // value being compared against
 674           Node   *bot_in = NULL;
 675           if( check_compare_clipping( true,  bot_if, min, bot_in ) &&
 676               check_compare_clipping( false, top_if, max, top_in ) ) {
 677             if( bot_in == top_in ) {
 678               PhaseIterGVN *gvn = phase->is_IterGVN();
 679               assert( gvn != NULL, "Only had DefUse info in IterGVN");
 680               // Only remaining check is that bot_in == top_in == (Phi's val + mods)
 681 
 682               // Check for the ConvF2INode
 683               ConvF2INode *convf2i;
 684               if( check_convf2i_clipping( phi, val_idx, convf2i, min, max ) &&
 685                 convf2i->in(1) == bot_in ) {
 686                 // Matched pattern, including LShiftI; RShiftI, replace with integer compares
 687                 // max test
 688                 Node *cmp   = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, min ));
 689                 Node *boo   = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::lt ));
 690                 IfNode *iff = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( top_if->in(0), boo, PROB_UNLIKELY_MAG(5), top_if->_fcnt ));
 691                 Node *if_min= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
 692                 Node *ifF   = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
 693                 // min test
 694                 cmp         = gvn->register_new_node_with_optimizer(new CmpINode( convf2i, max ));
 695                 boo         = gvn->register_new_node_with_optimizer(new BoolNode( cmp, BoolTest::gt ));
 696                 iff         = (IfNode*)gvn->register_new_node_with_optimizer(new IfNode( ifF, boo, PROB_UNLIKELY_MAG(5), bot_if->_fcnt ));
 697                 Node *if_max= gvn->register_new_node_with_optimizer(new IfTrueNode (iff));
 698                 ifF         = gvn->register_new_node_with_optimizer(new IfFalseNode(iff));
 699                 // update input edges to region node
 700                 set_req_X( min_idx, if_min, gvn );
 701                 set_req_X( max_idx, if_max, gvn );
 702                 set_req_X( val_idx, ifF,    gvn );
 703                 // remove unnecessary 'LShiftI; RShiftI' idiom
 704                 gvn->hash_delete(phi);
 705                 phi->set_req_X( val_idx, convf2i, gvn );
 706                 gvn->hash_find_insert(phi);
 707                 // Return transformed region node
 708                 return this;
 709               }
 710             }
 711           }
 712         }
 713       }
 714     }
 715   }
 716 
 717   if (can_reshape) {
 718     modified |= optimize_trichotomy(phase->is_IterGVN());
 719   }
 720 
 721   return modified ? this : NULL;
 722 }
 723 
 724 //------------------------------optimize_trichotomy--------------------------
 725 // Optimize nested comparisons of the following kind:
 726 // 
 727 // int compare(int a, int b) {
 728 //   return (a < b) ? -1 : (a == b) ? 0 : 1;
 729 // }
 730 //
 731 // Shape 1:
 732 // if (compare(a, b) == 1) { ... } -> if (a > b) { ... }
 733 //
 734 // Shape 2:
 735 // if (compare(a, b) == 0) { ... } -> if (a == b) { ... }
 736 // 
 737 // Above code leads to the following IR shapes where both Ifs compare the
 738 // same value and two out of three region inputs idx1 and idx2 map to
 739 // the same value and control flow.
 740 //
 741 // (1)   If                 (2)   If
 742 //      /  \                     /  \
 743 //   Proj  Proj               Proj  Proj
 744 //     |      \                |      \
 745 //     |       If              |      If                      If
 746 //     |      /  \             |     /  \                    /  \
 747 //     |   Proj  Proj          |  Proj  Proj      ==>     Proj  Proj
 748 //     |   /      /            \    |    /                  |    /
 749 //    Region     /              \   |   /                   |   /
 750 //         \    /                \  |  /                    |  /
 751 //         Region                Region                    Region
 752 //
 753 // The method returns true if 'this' is modified and false otherwise.
 754 bool RegionNode::optimize_trichotomy(PhaseIterGVN* igvn) {
 755   int idx1 = 1, idx2 = 2;
 756   Node* region = NULL;
 757   if (req() == 3 && in(1) != NULL && in(2) != NULL) {
 758     // Shape 1: Check if one of the inputs is a region that merges two control
 759     // inputs and has no other users (especially no Phi users).
 760     region = in(1)->isa_Region() ? in(1) : in(2)->isa_Region();
 761     if (region == NULL || region->outcnt() != 2 || region->req() != 3) {
 762       return false; // No suitable region input found
 763     }
 764   } else if (req() == 4) {
 765     // Shape 2: Check if two control inputs map to the same value of the unique phi
 766     // user and treat these as if they would come from another region (shape (1)).
 767     PhiNode* phi = has_unique_phi();
 768     if (phi == NULL) {
 769       return false; // No unique phi user
 770     }
 771     if (phi->in(idx1) != phi->in(idx2)) {
 772       idx2 = 3;
 773       if (phi->in(idx1) != phi->in(idx2)) {
 774         idx1 = 2;
 775         if (phi->in(idx1) != phi->in(idx2)) {
 776           return false; // No equal phi inputs found
 777         }
 778       }
 779     }
 780     assert(phi->in(idx1) == phi->in(idx2), "must be"); // Region is merging same value
 781     region = this;
 782   }
 783   if (region == NULL || region->in(idx1) == NULL || region->in(idx2) == NULL) {
 784     return false; // Region does not merge two control inputs
 785   }
 786   // At this point we know that region->in(idx1) and region->(idx2) map to the same
 787   // value and control flow. Now search for ifs that feed into these region inputs.
 788   ProjNode* proj1 = region->in(idx1)->isa_Proj();
 789   ProjNode* proj2 = region->in(idx2)->isa_Proj();
 790   if (proj1 == NULL || proj1->outcnt() != 1 ||
 791       proj2 == NULL || proj2->outcnt() != 1) {
 792     return false; // No projection inputs with region as unique user found
 793   }
 794   IfNode* iff1 = proj1->in(0)->isa_If();
 795   IfNode* iff2 = proj2->in(0)->isa_If();
 796   if (iff1 == NULL || iff1->outcnt() != 2 ||
 797       iff2 == NULL || iff2->outcnt() != 2) {
 798     return false; // No ifs found
 799   }
 800   if (iff1 == iff2) {
 801     igvn->replace_input_of(region, idx1, iff1->in(0));
 802     igvn->replace_input_of(region, idx2, igvn->C->top());
 803     return (region == this); // Remove useless if (both projections map to the same control/value)
 804   }
 805   BoolNode* bol1 = iff1->in(1)->isa_Bool();
 806   BoolNode* bol2 = iff2->in(1)->isa_Bool();
 807   if (bol1 == NULL || bol2 == NULL || bol1->in(1) != bol2->in(1)) {
 808     return false; // Ifs are not comparing the same value
 809   }
 810   proj1 = proj1->other_if_proj();
 811   proj2 = proj2->other_if_proj();
 812   if (!((proj1->unique_ctrl_out() == iff2 &&
 813          proj2->unique_ctrl_out() == this) ||
 814         (proj2->unique_ctrl_out() == iff1 &&
 815          proj1->unique_ctrl_out() == this))) {
 816     return false; // Ifs are not connected through other projs
 817   }
 818   // Found 'iff -> proj -> iff -> proj -> this' shape where all other projs are merged
 819   // through 'region' and map to the same value. Merge the boolean tests and replace
 820   // the ifs by a single comparison.
 821   BoolTest test1 = (proj1->_con == 1) ? bol1->_test : bol1->_test.negate();
 822   BoolTest test2 = (proj2->_con == 1) ? bol2->_test : bol2->_test.negate();
 823   BoolTest::mask res = test1.merge(test2);
 824   // Adjust iff1 to always pass (only iff2 will remain)
 825   igvn->replace_input_of(iff1, 1, igvn->intcon(proj1->_con));
 826   if (res == BoolTest::never) {
 827     // Merged test is always false, adjust iff2 to always fail
 828     igvn->replace_input_of(iff2, 1, igvn->intcon(1 - proj2->_con));
 829   } else {
 830     // Replace bool input of iff2 with merged test
 831     assert(res != BoolTest::illegal, "Unexpected bool result %d", res);
 832     BoolNode* new_bol = new BoolNode(bol2->in(1), res);
 833     igvn->replace_input_of(iff2, 1, igvn->transform((proj2->_con == 1) ? new_bol : new_bol->negate(igvn)));
 834   }
 835   return false;
 836 }
 837 
 838 const RegMask &RegionNode::out_RegMask() const {
 839   return RegMask::Empty;
 840 }
 841 
 842 // Find the one non-null required input.  RegionNode only
 843 Node *Node::nonnull_req() const {
 844   assert( is_Region(), "" );
 845   for( uint i = 1; i < _cnt; i++ )
 846     if( in(i) )
 847       return in(i);
 848   ShouldNotReachHere();
 849   return NULL;
 850 }
 851 
 852 
 853 //=============================================================================
 854 // note that these functions assume that the _adr_type field is flattened
 855 uint PhiNode::hash() const {
 856   const Type* at = _adr_type;
 857   return TypeNode::hash() + (at ? at->hash() : 0);
 858 }
 859 uint PhiNode::cmp( const Node &n ) const {
 860   return TypeNode::cmp(n) && _adr_type == ((PhiNode&)n)._adr_type;
 861 }
 862 static inline
 863 const TypePtr* flatten_phi_adr_type(const TypePtr* at) {
 864   if (at == NULL || at == TypePtr::BOTTOM)  return at;
 865   return Compile::current()->alias_type(at)->adr_type();
 866 }
 867 
 868 //----------------------------make---------------------------------------------
 869 // create a new phi with edges matching r and set (initially) to x
 870 PhiNode* PhiNode::make(Node* r, Node* x, const Type *t, const TypePtr* at) {
 871   uint preds = r->req();   // Number of predecessor paths
 872   assert(t != Type::MEMORY || at == flatten_phi_adr_type(at), "flatten at");
 873   PhiNode* p = new PhiNode(r, t, at);
 874   for (uint j = 1; j < preds; j++) {
 875     // Fill in all inputs, except those which the region does not yet have
 876     if (r->in(j) != NULL)
 877       p->init_req(j, x);
 878   }
 879   return p;
 880 }
 881 PhiNode* PhiNode::make(Node* r, Node* x) {
 882   const Type*    t  = x->bottom_type();
 883   const TypePtr* at = NULL;
 884   if (t == Type::MEMORY)  at = flatten_phi_adr_type(x->adr_type());
 885   return make(r, x, t, at);
 886 }
 887 PhiNode* PhiNode::make_blank(Node* r, Node* x) {
 888   const Type*    t  = x->bottom_type();
 889   const TypePtr* at = NULL;
 890   if (t == Type::MEMORY)  at = flatten_phi_adr_type(x->adr_type());
 891   return new PhiNode(r, t, at);
 892 }
 893 
 894 
 895 //------------------------slice_memory-----------------------------------------
 896 // create a new phi with narrowed memory type
 897 PhiNode* PhiNode::slice_memory(const TypePtr* adr_type) const {
 898   PhiNode* mem = (PhiNode*) clone();
 899   *(const TypePtr**)&mem->_adr_type = adr_type;
 900   // convert self-loops, or else we get a bad graph
 901   for (uint i = 1; i < req(); i++) {
 902     if ((const Node*)in(i) == this)  mem->set_req(i, mem);
 903   }
 904   mem->verify_adr_type();
 905   return mem;
 906 }
 907 
 908 //------------------------split_out_instance-----------------------------------
 909 // Split out an instance type from a bottom phi.
 910 PhiNode* PhiNode::split_out_instance(const TypePtr* at, PhaseIterGVN *igvn) const {
 911   const TypeOopPtr *t_oop = at->isa_oopptr();
 912   assert(t_oop != NULL && t_oop->is_known_instance(), "expecting instance oopptr");
 913   const TypePtr *t = adr_type();
 914   assert(type() == Type::MEMORY &&
 915          (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ||
 916           t->isa_oopptr() && !t->is_oopptr()->is_known_instance() &&
 917           t->is_oopptr()->cast_to_exactness(true)
 918            ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
 919            ->is_oopptr()->cast_to_instance_id(t_oop->instance_id()) == t_oop),
 920          "bottom or raw memory required");
 921 
 922   // Check if an appropriate node already exists.
 923   Node *region = in(0);
 924   for (DUIterator_Fast kmax, k = region->fast_outs(kmax); k < kmax; k++) {
 925     Node* use = region->fast_out(k);
 926     if( use->is_Phi()) {
 927       PhiNode *phi2 = use->as_Phi();
 928       if (phi2->type() == Type::MEMORY && phi2->adr_type() == at) {
 929         return phi2;
 930       }
 931     }
 932   }
 933   Compile *C = igvn->C;
 934   Arena *a = Thread::current()->resource_area();
 935   Node_Array node_map = new Node_Array(a);
 936   Node_Stack stack(a, C->live_nodes() >> 4);
 937   PhiNode *nphi = slice_memory(at);
 938   igvn->register_new_node_with_optimizer( nphi );
 939   node_map.map(_idx, nphi);
 940   stack.push((Node *)this, 1);
 941   while(!stack.is_empty()) {
 942     PhiNode *ophi = stack.node()->as_Phi();
 943     uint i = stack.index();
 944     assert(i >= 1, "not control edge");
 945     stack.pop();
 946     nphi = node_map[ophi->_idx]->as_Phi();
 947     for (; i < ophi->req(); i++) {
 948       Node *in = ophi->in(i);
 949       if (in == NULL || igvn->type(in) == Type::TOP)
 950         continue;
 951       Node *opt = MemNode::optimize_simple_memory_chain(in, t_oop, NULL, igvn);
 952       PhiNode *optphi = opt->is_Phi() ? opt->as_Phi() : NULL;
 953       if (optphi != NULL && optphi->adr_type() == TypePtr::BOTTOM) {
 954         opt = node_map[optphi->_idx];
 955         if (opt == NULL) {
 956           stack.push(ophi, i);
 957           nphi = optphi->slice_memory(at);
 958           igvn->register_new_node_with_optimizer( nphi );
 959           node_map.map(optphi->_idx, nphi);
 960           ophi = optphi;
 961           i = 0; // will get incremented at top of loop
 962           continue;
 963         }
 964       }
 965       nphi->set_req(i, opt);
 966     }
 967   }
 968   return nphi;
 969 }
 970 
 971 //------------------------verify_adr_type--------------------------------------
 972 #ifdef ASSERT
 973 void PhiNode::verify_adr_type(VectorSet& visited, const TypePtr* at) const {
 974   if (visited.test_set(_idx))  return;  //already visited
 975 
 976   // recheck constructor invariants:
 977   verify_adr_type(false);
 978 
 979   // recheck local phi/phi consistency:
 980   assert(_adr_type == at || _adr_type == TypePtr::BOTTOM,
 981          "adr_type must be consistent across phi nest");
 982 
 983   // walk around
 984   for (uint i = 1; i < req(); i++) {
 985     Node* n = in(i);
 986     if (n == NULL)  continue;
 987     const Node* np = in(i);
 988     if (np->is_Phi()) {
 989       np->as_Phi()->verify_adr_type(visited, at);
 990     } else if (n->bottom_type() == Type::TOP
 991                || (n->is_Mem() && n->in(MemNode::Address)->bottom_type() == Type::TOP)) {
 992       // ignore top inputs
 993     } else {
 994       const TypePtr* nat = flatten_phi_adr_type(n->adr_type());
 995       // recheck phi/non-phi consistency at leaves:
 996       assert((nat != NULL) == (at != NULL), "");
 997       assert(nat == at || nat == TypePtr::BOTTOM,
 998              "adr_type must be consistent at leaves of phi nest");
 999     }
1000   }
1001 }
1002 
1003 // Verify a whole nest of phis rooted at this one.
1004 void PhiNode::verify_adr_type(bool recursive) const {
1005   if (VMError::is_error_reported())  return;  // muzzle asserts when debugging an error
1006   if (Node::in_dump())               return;  // muzzle asserts when printing
1007 
1008   assert((_type == Type::MEMORY) == (_adr_type != NULL), "adr_type for memory phis only");
1009 
1010   if (!VerifyAliases)       return;  // verify thoroughly only if requested
1011 
1012   assert(_adr_type == flatten_phi_adr_type(_adr_type),
1013          "Phi::adr_type must be pre-normalized");
1014 
1015   if (recursive) {
1016     VectorSet visited(Thread::current()->resource_area());
1017     verify_adr_type(visited, _adr_type);
1018   }
1019 }
1020 #endif
1021 
1022 
1023 //------------------------------Value------------------------------------------
1024 // Compute the type of the PhiNode
1025 const Type* PhiNode::Value(PhaseGVN* phase) const {
1026   Node *r = in(0);              // RegionNode
1027   if( !r )                      // Copy or dead
1028     return in(1) ? phase->type(in(1)) : Type::TOP;
1029 
1030   // Note: During parsing, phis are often transformed before their regions.
1031   // This means we have to use type_or_null to defend against untyped regions.
1032   if( phase->type_or_null(r) == Type::TOP )  // Dead code?
1033     return Type::TOP;
1034 
1035   // Check for trip-counted loop.  If so, be smarter.
1036   CountedLoopNode* l = r->is_CountedLoop() ? r->as_CountedLoop() : NULL;
1037   if (l && ((const Node*)l->phi() == this)) { // Trip counted loop!
1038     // protect against init_trip() or limit() returning NULL
1039     if (l->can_be_counted_loop(phase)) {
1040       const Node *init   = l->init_trip();
1041       const Node *limit  = l->limit();
1042       const Node* stride = l->stride();
1043       if (init != NULL && limit != NULL && stride != NULL) {
1044         const TypeInt* lo = phase->type(init)->isa_int();
1045         const TypeInt* hi = phase->type(limit)->isa_int();
1046         const TypeInt* stride_t = phase->type(stride)->isa_int();
1047         if (lo != NULL && hi != NULL && stride_t != NULL) { // Dying loops might have TOP here
1048           assert(stride_t->_hi >= stride_t->_lo, "bad stride type");
1049           BoolTest::mask bt = l->loopexit()->test_trip();
1050           // If the loop exit condition is "not equal", the condition
1051           // would not trigger if init > limit (if stride > 0) or if
1052           // init < limit if (stride > 0) so we can't deduce bounds
1053           // for the iv from the exit condition.
1054           if (bt != BoolTest::ne) {
1055             if (stride_t->_hi < 0) {          // Down-counter loop
1056               swap(lo, hi);
1057               return TypeInt::make(MIN2(lo->_lo, hi->_lo) , hi->_hi, 3);
1058             } else if (stride_t->_lo >= 0) {
1059               return TypeInt::make(lo->_lo, MAX2(lo->_hi, hi->_hi), 3);
1060             }
1061           }
1062         }
1063       }
1064     } else if (l->in(LoopNode::LoopBackControl) != NULL &&
1065                in(LoopNode::EntryControl) != NULL &&
1066                phase->type(l->in(LoopNode::LoopBackControl)) == Type::TOP) {
1067       // During CCP, if we saturate the type of a counted loop's Phi
1068       // before the special code for counted loop above has a chance
1069       // to run (that is as long as the type of the backedge's control
1070       // is top), we might end up with non monotonic types
1071       return phase->type(in(LoopNode::EntryControl))->filter_speculative(_type);
1072     }
1073   }
1074 
1075   // Until we have harmony between classes and interfaces in the type
1076   // lattice, we must tread carefully around phis which implicitly
1077   // convert the one to the other.
1078   const TypePtr* ttp = _type->make_ptr();
1079   const TypeInstPtr* ttip = (ttp != NULL) ? ttp->isa_instptr() : NULL;
1080   const TypeKlassPtr* ttkp = (ttp != NULL) ? ttp->isa_klassptr() : NULL;
1081   bool is_intf = false;
1082   if (ttip != NULL) {
1083     ciKlass* k = ttip->klass();
1084     if (k->is_loaded() && k->is_interface())
1085       is_intf = true;
1086   }
1087   if (ttkp != NULL) {
1088     ciKlass* k = ttkp->klass();
1089     if (k->is_loaded() && k->is_interface())
1090       is_intf = true;
1091   }
1092 
1093   // Default case: merge all inputs
1094   const Type *t = Type::TOP;        // Merged type starting value
1095   for (uint i = 1; i < req(); ++i) {// For all paths in
1096     // Reachable control path?
1097     if (r->in(i) && phase->type(r->in(i)) == Type::CONTROL) {
1098       const Type* ti = phase->type(in(i));
1099       // We assume that each input of an interface-valued Phi is a true
1100       // subtype of that interface.  This might not be true of the meet
1101       // of all the input types.  The lattice is not distributive in
1102       // such cases.  Ward off asserts in type.cpp by refusing to do
1103       // meets between interfaces and proper classes.
1104       const TypePtr* tip = ti->make_ptr();
1105       const TypeInstPtr* tiip = (tip != NULL) ? tip->isa_instptr() : NULL;
1106       if (tiip) {
1107         bool ti_is_intf = false;
1108         ciKlass* k = tiip->klass();
1109         if (k->is_loaded() && k->is_interface())
1110           ti_is_intf = true;
1111         if (is_intf != ti_is_intf)
1112           { t = _type; break; }
1113       }
1114       t = t->meet_speculative(ti);
1115     }
1116   }
1117 
1118   // The worst-case type (from ciTypeFlow) should be consistent with "t".
1119   // That is, we expect that "t->higher_equal(_type)" holds true.
1120   // There are various exceptions:
1121   // - Inputs which are phis might in fact be widened unnecessarily.
1122   //   For example, an input might be a widened int while the phi is a short.
1123   // - Inputs might be BotPtrs but this phi is dependent on a null check,
1124   //   and postCCP has removed the cast which encodes the result of the check.
1125   // - The type of this phi is an interface, and the inputs are classes.
1126   // - Value calls on inputs might produce fuzzy results.
1127   //   (Occurrences of this case suggest improvements to Value methods.)
1128   //
1129   // It is not possible to see Type::BOTTOM values as phi inputs,
1130   // because the ciTypeFlow pre-pass produces verifier-quality types.
1131   const Type* ft = t->filter_speculative(_type);  // Worst case type
1132 
1133 #ifdef ASSERT
1134   // The following logic has been moved into TypeOopPtr::filter.
1135   const Type* jt = t->join_speculative(_type);
1136   if (jt->empty()) {           // Emptied out???
1137 
1138     // Check for evil case of 't' being a class and '_type' expecting an
1139     // interface.  This can happen because the bytecodes do not contain
1140     // enough type info to distinguish a Java-level interface variable
1141     // from a Java-level object variable.  If we meet 2 classes which
1142     // both implement interface I, but their meet is at 'j/l/O' which
1143     // doesn't implement I, we have no way to tell if the result should
1144     // be 'I' or 'j/l/O'.  Thus we'll pick 'j/l/O'.  If this then flows
1145     // into a Phi which "knows" it's an Interface type we'll have to
1146     // uplift the type.
1147     if (!t->empty() && ttip && ttip->is_loaded() && ttip->klass()->is_interface()) {
1148       assert(ft == _type, ""); // Uplift to interface
1149     } else if (!t->empty() && ttkp && ttkp->is_loaded() && ttkp->klass()->is_interface()) {
1150       assert(ft == _type, ""); // Uplift to interface
1151     } else {
1152       // We also have to handle 'evil cases' of interface- vs. class-arrays
1153       Type::get_arrays_base_elements(jt, _type, NULL, &ttip);
1154       if (!t->empty() && ttip != NULL && ttip->is_loaded() && ttip->klass()->is_interface()) {
1155           assert(ft == _type, "");   // Uplift to array of interface
1156       } else {
1157         // Otherwise it's something stupid like non-overlapping int ranges
1158         // found on dying counted loops.
1159         assert(ft == Type::TOP, ""); // Canonical empty value
1160       }
1161     }
1162   }
1163 
1164   else {
1165 
1166     // If we have an interface-typed Phi and we narrow to a class type, the join
1167     // should report back the class.  However, if we have a J/L/Object
1168     // class-typed Phi and an interface flows in, it's possible that the meet &
1169     // join report an interface back out.  This isn't possible but happens
1170     // because the type system doesn't interact well with interfaces.
1171     const TypePtr *jtp = jt->make_ptr();
1172     const TypeInstPtr *jtip = (jtp != NULL) ? jtp->isa_instptr() : NULL;
1173     const TypeKlassPtr *jtkp = (jtp != NULL) ? jtp->isa_klassptr() : NULL;
1174     if( jtip && ttip ) {
1175       if( jtip->is_loaded() &&  jtip->klass()->is_interface() &&
1176           ttip->is_loaded() && !ttip->klass()->is_interface() ) {
1177         assert(ft == ttip->cast_to_ptr_type(jtip->ptr()) ||
1178                ft->isa_narrowoop() && ft->make_ptr() == ttip->cast_to_ptr_type(jtip->ptr()), "");
1179         jt = ft;
1180       }
1181     }
1182     if( jtkp && ttkp ) {
1183       if( jtkp->is_loaded() &&  jtkp->klass()->is_interface() &&
1184           !jtkp->klass_is_exact() && // Keep exact interface klass (6894807)
1185           ttkp->is_loaded() && !ttkp->klass()->is_interface() ) {
1186         assert(ft == ttkp->cast_to_ptr_type(jtkp->ptr()) ||
1187                ft->isa_narrowklass() && ft->make_ptr() == ttkp->cast_to_ptr_type(jtkp->ptr()), "");
1188         jt = ft;
1189       }
1190     }
1191     if (jt != ft && jt->base() == ft->base()) {
1192       if (jt->isa_int() &&
1193           jt->is_int()->_lo == ft->is_int()->_lo &&
1194           jt->is_int()->_hi == ft->is_int()->_hi)
1195         jt = ft;
1196       if (jt->isa_long() &&
1197           jt->is_long()->_lo == ft->is_long()->_lo &&
1198           jt->is_long()->_hi == ft->is_long()->_hi)
1199         jt = ft;
1200     }
1201     if (jt != ft) {
1202       tty->print("merge type:  "); t->dump(); tty->cr();
1203       tty->print("kill type:   "); _type->dump(); tty->cr();
1204       tty->print("join type:   "); jt->dump(); tty->cr();
1205       tty->print("filter type: "); ft->dump(); tty->cr();
1206     }
1207     assert(jt == ft, "");
1208   }
1209 #endif //ASSERT
1210 
1211   // Deal with conversion problems found in data loops.
1212   ft = phase->saturate(ft, phase->type_or_null(this), _type);
1213 
1214   return ft;
1215 }
1216 
1217 
1218 //------------------------------is_diamond_phi---------------------------------
1219 // Does this Phi represent a simple well-shaped diamond merge?  Return the
1220 // index of the true path or 0 otherwise.
1221 // If check_control_only is true, do not inspect the If node at the
1222 // top, and return -1 (not an edge number) on success.
1223 int PhiNode::is_diamond_phi(bool check_control_only) const {
1224   // Check for a 2-path merge
1225   Node *region = in(0);
1226   if( !region ) return 0;
1227   if( region->req() != 3 ) return 0;
1228   if(         req() != 3 ) return 0;
1229   // Check that both paths come from the same If
1230   Node *ifp1 = region->in(1);
1231   Node *ifp2 = region->in(2);
1232   if( !ifp1 || !ifp2 ) return 0;
1233   Node *iff = ifp1->in(0);
1234   if( !iff || !iff->is_If() ) return 0;
1235   if( iff != ifp2->in(0) ) return 0;
1236   if (check_control_only)  return -1;
1237   // Check for a proper bool/cmp
1238   const Node *b = iff->in(1);
1239   if( !b->is_Bool() ) return 0;
1240   const Node *cmp = b->in(1);
1241   if( !cmp->is_Cmp() ) return 0;
1242 
1243   // Check for branching opposite expected
1244   if( ifp2->Opcode() == Op_IfTrue ) {
1245     assert( ifp1->Opcode() == Op_IfFalse, "" );
1246     return 2;
1247   } else {
1248     assert( ifp1->Opcode() == Op_IfTrue, "" );
1249     return 1;
1250   }
1251 }
1252 
1253 //----------------------------check_cmove_id-----------------------------------
1254 // Check for CMove'ing a constant after comparing against the constant.
1255 // Happens all the time now, since if we compare equality vs a constant in
1256 // the parser, we "know" the variable is constant on one path and we force
1257 // it.  Thus code like "if( x==0 ) {/*EMPTY*/}" ends up inserting a
1258 // conditional move: "x = (x==0)?0:x;".  Yucko.  This fix is slightly more
1259 // general in that we don't need constants.  Since CMove's are only inserted
1260 // in very special circumstances, we do it here on generic Phi's.
1261 Node* PhiNode::is_cmove_id(PhaseTransform* phase, int true_path) {
1262   assert(true_path !=0, "only diamond shape graph expected");
1263 
1264   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1265   // phi->region->if_proj->ifnode->bool->cmp
1266   Node*     region = in(0);
1267   Node*     iff    = region->in(1)->in(0);
1268   BoolNode* b      = iff->in(1)->as_Bool();
1269   Node*     cmp    = b->in(1);
1270   Node*     tval   = in(true_path);
1271   Node*     fval   = in(3-true_path);
1272   Node*     id     = CMoveNode::is_cmove_id(phase, cmp, tval, fval, b);
1273   if (id == NULL)
1274     return NULL;
1275 
1276   // Either value might be a cast that depends on a branch of 'iff'.
1277   // Since the 'id' value will float free of the diamond, either
1278   // decast or return failure.
1279   Node* ctl = id->in(0);
1280   if (ctl != NULL && ctl->in(0) == iff) {
1281     if (id->is_ConstraintCast()) {
1282       return id->in(1);
1283     } else {
1284       // Don't know how to disentangle this value.
1285       return NULL;
1286     }
1287   }
1288 
1289   return id;
1290 }
1291 
1292 //------------------------------Identity---------------------------------------
1293 // Check for Region being Identity.
1294 Node* PhiNode::Identity(PhaseGVN* phase) {
1295   // Check for no merging going on
1296   // (There used to be special-case code here when this->region->is_Loop.
1297   // It would check for a tributary phi on the backedge that the main phi
1298   // trivially, perhaps with a single cast.  The unique_input method
1299   // does all this and more, by reducing such tributaries to 'this'.)
1300   Node* uin = unique_input(phase, false);
1301   if (uin != NULL) {
1302     return uin;
1303   }
1304 
1305   int true_path = is_diamond_phi();
1306   if (true_path != 0) {
1307     Node* id = is_cmove_id(phase, true_path);
1308     if (id != NULL)  return id;
1309   }
1310 
1311   return this;                     // No identity
1312 }
1313 
1314 //-----------------------------unique_input------------------------------------
1315 // Find the unique value, discounting top, self-loops, and casts.
1316 // Return top if there are no inputs, and self if there are multiple.
1317 Node* PhiNode::unique_input(PhaseTransform* phase, bool uncast) {
1318   //  1) One unique direct input,
1319   // or if uncast is true:
1320   //  2) some of the inputs have an intervening ConstraintCast
1321   //  3) an input is a self loop
1322   //
1323   //  1) input   or   2) input     or   3) input __
1324   //     /   \           /   \               \  /  \
1325   //     \   /          |    cast             phi  cast
1326   //      phi            \   /               /  \  /
1327   //                      phi               /    --
1328 
1329   Node* r = in(0);                      // RegionNode
1330   if (r == NULL)  return in(1);         // Already degraded to a Copy
1331   Node* input = NULL; // The unique direct input (maybe uncasted = ConstraintCasts removed)
1332 
1333   for (uint i = 1, cnt = req(); i < cnt; ++i) {
1334     Node* rc = r->in(i);
1335     if (rc == NULL || phase->type(rc) == Type::TOP)
1336       continue;                 // ignore unreachable control path
1337     Node* n = in(i);
1338     if (n == NULL)
1339       continue;
1340     Node* un = n;
1341     if (uncast) {
1342 #ifdef ASSERT
1343       Node* m = un->uncast();
1344 #endif
1345       while (un != NULL && un->req() == 2 && un->is_ConstraintCast()) {
1346         Node* next = un->in(1);
1347         if (phase->type(next)->isa_rawptr() && phase->type(un)->isa_oopptr()) {
1348           // risk exposing raw ptr at safepoint
1349           break;
1350         }
1351         un = next;
1352       }
1353       assert(m == un || un->in(1) == m, "Only expected at CheckCastPP from allocation");
1354     }
1355     if (un == NULL || un == this || phase->type(un) == Type::TOP) {
1356       continue; // ignore if top, or in(i) and "this" are in a data cycle
1357     }
1358     // Check for a unique input (maybe uncasted)
1359     if (input == NULL) {
1360       input = un;
1361     } else if (input != un) {
1362       input = NodeSentinel; // no unique input
1363     }
1364   }
1365   if (input == NULL) {
1366     return phase->C->top();        // no inputs
1367   }
1368 
1369   if (input != NodeSentinel) {
1370     return input;           // one unique direct input
1371   }
1372 
1373   // Nothing.
1374   return NULL;
1375 }
1376 
1377 //------------------------------is_x2logic-------------------------------------
1378 // Check for simple convert-to-boolean pattern
1379 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)
1380 // Convert Phi to an ConvIB.
1381 static Node *is_x2logic( PhaseGVN *phase, PhiNode *phi, int true_path ) {
1382   assert(true_path !=0, "only diamond shape graph expected");
1383   // Convert the true/false index into an expected 0/1 return.
1384   // Map 2->0 and 1->1.
1385   int flipped = 2-true_path;
1386 
1387   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1388   // phi->region->if_proj->ifnode->bool->cmp
1389   Node *region = phi->in(0);
1390   Node *iff = region->in(1)->in(0);
1391   BoolNode *b = (BoolNode*)iff->in(1);
1392   const CmpNode *cmp = (CmpNode*)b->in(1);
1393 
1394   Node *zero = phi->in(1);
1395   Node *one  = phi->in(2);
1396   const Type *tzero = phase->type( zero );
1397   const Type *tone  = phase->type( one  );
1398 
1399   // Check for compare vs 0
1400   const Type *tcmp = phase->type(cmp->in(2));
1401   if( tcmp != TypeInt::ZERO && tcmp != TypePtr::NULL_PTR ) {
1402     // Allow cmp-vs-1 if the other input is bounded by 0-1
1403     if( !(tcmp == TypeInt::ONE && phase->type(cmp->in(1)) == TypeInt::BOOL) )
1404       return NULL;
1405     flipped = 1-flipped;        // Test is vs 1 instead of 0!
1406   }
1407 
1408   // Check for setting zero/one opposite expected
1409   if( tzero == TypeInt::ZERO ) {
1410     if( tone == TypeInt::ONE ) {
1411     } else return NULL;
1412   } else if( tzero == TypeInt::ONE ) {
1413     if( tone == TypeInt::ZERO ) {
1414       flipped = 1-flipped;
1415     } else return NULL;
1416   } else return NULL;
1417 
1418   // Check for boolean test backwards
1419   if( b->_test._test == BoolTest::ne ) {
1420   } else if( b->_test._test == BoolTest::eq ) {
1421     flipped = 1-flipped;
1422   } else return NULL;
1423 
1424   // Build int->bool conversion
1425   Node *n = new Conv2BNode( cmp->in(1) );
1426   if( flipped )
1427     n = new XorINode( phase->transform(n), phase->intcon(1) );
1428 
1429   return n;
1430 }
1431 
1432 //------------------------------is_cond_add------------------------------------
1433 // Check for simple conditional add pattern:  "(P < Q) ? X+Y : X;"
1434 // To be profitable the control flow has to disappear; there can be no other
1435 // values merging here.  We replace the test-and-branch with:
1436 // "(sgn(P-Q))&Y) + X".  Basically, convert "(P < Q)" into 0 or -1 by
1437 // moving the carry bit from (P-Q) into a register with 'sbb EAX,EAX'.
1438 // Then convert Y to 0-or-Y and finally add.
1439 // This is a key transform for SpecJava _201_compress.
1440 static Node* is_cond_add(PhaseGVN *phase, PhiNode *phi, int true_path) {
1441   assert(true_path !=0, "only diamond shape graph expected");
1442 
1443   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1444   // phi->region->if_proj->ifnode->bool->cmp
1445   RegionNode *region = (RegionNode*)phi->in(0);
1446   Node *iff = region->in(1)->in(0);
1447   BoolNode* b = iff->in(1)->as_Bool();
1448   const CmpNode *cmp = (CmpNode*)b->in(1);
1449 
1450   // Make sure only merging this one phi here
1451   if (region->has_unique_phi() != phi)  return NULL;
1452 
1453   // Make sure each arm of the diamond has exactly one output, which we assume
1454   // is the region.  Otherwise, the control flow won't disappear.
1455   if (region->in(1)->outcnt() != 1) return NULL;
1456   if (region->in(2)->outcnt() != 1) return NULL;
1457 
1458   // Check for "(P < Q)" of type signed int
1459   if (b->_test._test != BoolTest::lt)  return NULL;
1460   if (cmp->Opcode() != Op_CmpI)        return NULL;
1461 
1462   Node *p = cmp->in(1);
1463   Node *q = cmp->in(2);
1464   Node *n1 = phi->in(  true_path);
1465   Node *n2 = phi->in(3-true_path);
1466 
1467   int op = n1->Opcode();
1468   if( op != Op_AddI           // Need zero as additive identity
1469       /*&&op != Op_SubI &&
1470       op != Op_AddP &&
1471       op != Op_XorI &&
1472       op != Op_OrI*/ )
1473     return NULL;
1474 
1475   Node *x = n2;
1476   Node *y = NULL;
1477   if( x == n1->in(1) ) {
1478     y = n1->in(2);
1479   } else if( x == n1->in(2) ) {
1480     y = n1->in(1);
1481   } else return NULL;
1482 
1483   // Not so profitable if compare and add are constants
1484   if( q->is_Con() && phase->type(q) != TypeInt::ZERO && y->is_Con() )
1485     return NULL;
1486 
1487   Node *cmplt = phase->transform( new CmpLTMaskNode(p,q) );
1488   Node *j_and   = phase->transform( new AndINode(cmplt,y) );
1489   return new AddINode(j_and,x);
1490 }
1491 
1492 //------------------------------is_absolute------------------------------------
1493 // Check for absolute value.
1494 static Node* is_absolute( PhaseGVN *phase, PhiNode *phi_root, int true_path) {
1495   assert(true_path !=0, "only diamond shape graph expected");
1496 
1497   int  cmp_zero_idx = 0;        // Index of compare input where to look for zero
1498   int  phi_x_idx = 0;           // Index of phi input where to find naked x
1499 
1500   // ABS ends with the merge of 2 control flow paths.
1501   // Find the false path from the true path. With only 2 inputs, 3 - x works nicely.
1502   int false_path = 3 - true_path;
1503 
1504   // is_diamond_phi() has guaranteed the correctness of the nodes sequence:
1505   // phi->region->if_proj->ifnode->bool->cmp
1506   BoolNode *bol = phi_root->in(0)->in(1)->in(0)->in(1)->as_Bool();
1507 
1508   // Check bool sense
1509   switch( bol->_test._test ) {
1510   case BoolTest::lt: cmp_zero_idx = 1; phi_x_idx = true_path;  break;
1511   case BoolTest::le: cmp_zero_idx = 2; phi_x_idx = false_path; break;
1512   case BoolTest::gt: cmp_zero_idx = 2; phi_x_idx = true_path;  break;
1513   case BoolTest::ge: cmp_zero_idx = 1; phi_x_idx = false_path; break;
1514   default:           return NULL;                              break;
1515   }
1516 
1517   // Test is next
1518   Node *cmp = bol->in(1);
1519   const Type *tzero = NULL;
1520   switch( cmp->Opcode() ) {
1521   case Op_CmpF:    tzero = TypeF::ZERO; break; // Float ABS
1522   case Op_CmpD:    tzero = TypeD::ZERO; break; // Double ABS
1523   default: return NULL;
1524   }
1525 
1526   // Find zero input of compare; the other input is being abs'd
1527   Node *x = NULL;
1528   bool flip = false;
1529   if( phase->type(cmp->in(cmp_zero_idx)) == tzero ) {
1530     x = cmp->in(3 - cmp_zero_idx);
1531   } else if( phase->type(cmp->in(3 - cmp_zero_idx)) == tzero ) {
1532     // The test is inverted, we should invert the result...
1533     x = cmp->in(cmp_zero_idx);
1534     flip = true;
1535   } else {
1536     return NULL;
1537   }
1538 
1539   // Next get the 2 pieces being selected, one is the original value
1540   // and the other is the negated value.
1541   if( phi_root->in(phi_x_idx) != x ) return NULL;
1542 
1543   // Check other phi input for subtract node
1544   Node *sub = phi_root->in(3 - phi_x_idx);
1545 
1546   // Allow only Sub(0,X) and fail out for all others; Neg is not OK
1547   if( tzero == TypeF::ZERO ) {
1548     if( sub->Opcode() != Op_SubF ||
1549         sub->in(2) != x ||
1550         phase->type(sub->in(1)) != tzero ) return NULL;
1551     x = new AbsFNode(x);
1552     if (flip) {
1553       x = new SubFNode(sub->in(1), phase->transform(x));
1554     }
1555   } else {
1556     if( sub->Opcode() != Op_SubD ||
1557         sub->in(2) != x ||
1558         phase->type(sub->in(1)) != tzero ) return NULL;
1559     x = new AbsDNode(x);
1560     if (flip) {
1561       x = new SubDNode(sub->in(1), phase->transform(x));
1562     }
1563   }
1564 
1565   return x;
1566 }
1567 
1568 //------------------------------split_once-------------------------------------
1569 // Helper for split_flow_path
1570 static void split_once(PhaseIterGVN *igvn, Node *phi, Node *val, Node *n, Node *newn) {
1571   igvn->hash_delete(n);         // Remove from hash before hacking edges
1572 
1573   uint j = 1;
1574   for (uint i = phi->req()-1; i > 0; i--) {
1575     if (phi->in(i) == val) {   // Found a path with val?
1576       // Add to NEW Region/Phi, no DU info
1577       newn->set_req( j++, n->in(i) );
1578       // Remove from OLD Region/Phi
1579       n->del_req(i);
1580     }
1581   }
1582 
1583   // Register the new node but do not transform it.  Cannot transform until the
1584   // entire Region/Phi conglomerate has been hacked as a single huge transform.
1585   igvn->register_new_node_with_optimizer( newn );
1586 
1587   // Now I can point to the new node.
1588   n->add_req(newn);
1589   igvn->_worklist.push(n);
1590 }
1591 
1592 //------------------------------split_flow_path--------------------------------
1593 // Check for merging identical values and split flow paths
1594 static Node* split_flow_path(PhaseGVN *phase, PhiNode *phi) {
1595   BasicType bt = phi->type()->basic_type();
1596   if( bt == T_ILLEGAL || type2size[bt] <= 0 )
1597     return NULL;                // Bail out on funny non-value stuff
1598   if( phi->req() <= 3 )         // Need at least 2 matched inputs and a
1599     return NULL;                // third unequal input to be worth doing
1600 
1601   // Scan for a constant
1602   uint i;
1603   for( i = 1; i < phi->req()-1; i++ ) {
1604     Node *n = phi->in(i);
1605     if( !n ) return NULL;
1606     if( phase->type(n) == Type::TOP ) return NULL;
1607     if( n->Opcode() == Op_ConP || n->Opcode() == Op_ConN || n->Opcode() == Op_ConNKlass )
1608       break;
1609   }
1610   if( i >= phi->req() )         // Only split for constants
1611     return NULL;
1612 
1613   Node *val = phi->in(i);       // Constant to split for
1614   uint hit = 0;                 // Number of times it occurs
1615   Node *r = phi->region();
1616 
1617   for( ; i < phi->req(); i++ ){ // Count occurrences of constant
1618     Node *n = phi->in(i);
1619     if( !n ) return NULL;
1620     if( phase->type(n) == Type::TOP ) return NULL;
1621     if( phi->in(i) == val ) {
1622       hit++;
1623       if (PhaseIdealLoop::find_predicate(r->in(i)) != NULL) {
1624         return NULL;            // don't split loop entry path
1625       }
1626     }
1627   }
1628 
1629   if( hit <= 1 ||               // Make sure we find 2 or more
1630       hit == phi->req()-1 )     // and not ALL the same value
1631     return NULL;
1632 
1633   // Now start splitting out the flow paths that merge the same value.
1634   // Split first the RegionNode.
1635   PhaseIterGVN *igvn = phase->is_IterGVN();
1636   RegionNode *newr = new RegionNode(hit+1);
1637   split_once(igvn, phi, val, r, newr);
1638 
1639   // Now split all other Phis than this one
1640   for (DUIterator_Fast kmax, k = r->fast_outs(kmax); k < kmax; k++) {
1641     Node* phi2 = r->fast_out(k);
1642     if( phi2->is_Phi() && phi2->as_Phi() != phi ) {
1643       PhiNode *newphi = PhiNode::make_blank(newr, phi2);
1644       split_once(igvn, phi, val, phi2, newphi);
1645     }
1646   }
1647 
1648   // Clean up this guy
1649   igvn->hash_delete(phi);
1650   for( i = phi->req()-1; i > 0; i-- ) {
1651     if( phi->in(i) == val ) {
1652       phi->del_req(i);
1653     }
1654   }
1655   phi->add_req(val);
1656 
1657   return phi;
1658 }
1659 
1660 //=============================================================================
1661 //------------------------------simple_data_loop_check-------------------------
1662 //  Try to determining if the phi node in a simple safe/unsafe data loop.
1663 //  Returns:
1664 // enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };
1665 // Safe       - safe case when the phi and it's inputs reference only safe data
1666 //              nodes;
1667 // Unsafe     - the phi and it's inputs reference unsafe data nodes but there
1668 //              is no reference back to the phi - need a graph walk
1669 //              to determine if it is in a loop;
1670 // UnsafeLoop - unsafe case when the phi references itself directly or through
1671 //              unsafe data node.
1672 //  Note: a safe data node is a node which could/never reference itself during
1673 //  GVN transformations. For now it is Con, Proj, Phi, CastPP, CheckCastPP.
1674 //  I mark Phi nodes as safe node not only because they can reference itself
1675 //  but also to prevent mistaking the fallthrough case inside an outer loop
1676 //  as dead loop when the phi references itselfs through an other phi.
1677 PhiNode::LoopSafety PhiNode::simple_data_loop_check(Node *in) const {
1678   // It is unsafe loop if the phi node references itself directly.
1679   if (in == (Node*)this)
1680     return UnsafeLoop; // Unsafe loop
1681   // Unsafe loop if the phi node references itself through an unsafe data node.
1682   // Exclude cases with null inputs or data nodes which could reference
1683   // itself (safe for dead loops).
1684   if (in != NULL && !in->is_dead_loop_safe()) {
1685     // Check inputs of phi's inputs also.
1686     // It is much less expensive then full graph walk.
1687     uint cnt = in->req();
1688     uint i = (in->is_Proj() && !in->is_CFG())  ? 0 : 1;
1689     for (; i < cnt; ++i) {
1690       Node* m = in->in(i);
1691       if (m == (Node*)this)
1692         return UnsafeLoop; // Unsafe loop
1693       if (m != NULL && !m->is_dead_loop_safe()) {
1694         // Check the most common case (about 30% of all cases):
1695         // phi->Load/Store->AddP->(ConP ConP Con)/(Parm Parm Con).
1696         Node *m1 = (m->is_AddP() && m->req() > 3) ? m->in(1) : NULL;
1697         if (m1 == (Node*)this)
1698           return UnsafeLoop; // Unsafe loop
1699         if (m1 != NULL && m1 == m->in(2) &&
1700             m1->is_dead_loop_safe() && m->in(3)->is_Con()) {
1701           continue; // Safe case
1702         }
1703         // The phi references an unsafe node - need full analysis.
1704         return Unsafe;
1705       }
1706     }
1707   }
1708   return Safe; // Safe case - we can optimize the phi node.
1709 }
1710 
1711 //------------------------------is_unsafe_data_reference-----------------------
1712 // If phi can be reached through the data input - it is data loop.
1713 bool PhiNode::is_unsafe_data_reference(Node *in) const {
1714   assert(req() > 1, "");
1715   // First, check simple cases when phi references itself directly or
1716   // through an other node.
1717   LoopSafety safety = simple_data_loop_check(in);
1718   if (safety == UnsafeLoop)
1719     return true;  // phi references itself - unsafe loop
1720   else if (safety == Safe)
1721     return false; // Safe case - phi could be replaced with the unique input.
1722 
1723   // Unsafe case when we should go through data graph to determine
1724   // if the phi references itself.
1725 
1726   ResourceMark rm;
1727 
1728   Arena *a = Thread::current()->resource_area();
1729   Node_List nstack(a);
1730   VectorSet visited(a);
1731 
1732   nstack.push(in); // Start with unique input.
1733   visited.set(in->_idx);
1734   while (nstack.size() != 0) {
1735     Node* n = nstack.pop();
1736     uint cnt = n->req();
1737     uint i = (n->is_Proj() && !n->is_CFG()) ? 0 : 1;
1738     for (; i < cnt; i++) {
1739       Node* m = n->in(i);
1740       if (m == (Node*)this) {
1741         return true;    // Data loop
1742       }
1743       if (m != NULL && !m->is_dead_loop_safe()) { // Only look for unsafe cases.
1744         if (!visited.test_set(m->_idx))
1745           nstack.push(m);
1746       }
1747     }
1748   }
1749   return false; // The phi is not reachable from its inputs
1750 }
1751 
1752 
1753 //------------------------------Ideal------------------------------------------
1754 // Return a node which is more "ideal" than the current node.  Must preserve
1755 // the CFG, but we can still strip out dead paths.
1756 Node *PhiNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1757   // The next should never happen after 6297035 fix.
1758   if( is_copy() )               // Already degraded to a Copy ?
1759     return NULL;                // No change
1760 
1761   Node *r = in(0);              // RegionNode
1762   assert(r->in(0) == NULL || !r->in(0)->is_Root(), "not a specially hidden merge");
1763 
1764   // Note: During parsing, phis are often transformed before their regions.
1765   // This means we have to use type_or_null to defend against untyped regions.
1766   if( phase->type_or_null(r) == Type::TOP ) // Dead code?
1767     return NULL;                // No change
1768 
1769   Node *top = phase->C->top();
1770   bool new_phi = (outcnt() == 0); // transforming new Phi
1771   // No change for igvn if new phi is not hooked
1772   if (new_phi && can_reshape)
1773     return NULL;
1774 
1775   // The are 2 situations when only one valid phi's input is left
1776   // (in addition to Region input).
1777   // One: region is not loop - replace phi with this input.
1778   // Two: region is loop - replace phi with top since this data path is dead
1779   //                       and we need to break the dead data loop.
1780   Node* progress = NULL;        // Record if any progress made
1781   for( uint j = 1; j < req(); ++j ){ // For all paths in
1782     // Check unreachable control paths
1783     Node* rc = r->in(j);
1784     Node* n = in(j);            // Get the input
1785     if (rc == NULL || phase->type(rc) == Type::TOP) {
1786       if (n != top) {           // Not already top?
1787         PhaseIterGVN *igvn = phase->is_IterGVN();
1788         if (can_reshape && igvn != NULL) {
1789           igvn->_worklist.push(r);
1790         }
1791         set_req(j, top);        // Nuke it down
1792         progress = this;        // Record progress
1793       }
1794     }
1795   }
1796 
1797   if (can_reshape && outcnt() == 0) {
1798     // set_req() above may kill outputs if Phi is referenced
1799     // only by itself on the dead (top) control path.
1800     return top;
1801   }
1802 
1803   bool uncasted = false;
1804   Node* uin = unique_input(phase, false);
1805   if (uin == NULL && can_reshape) {
1806     uncasted = true;
1807     uin = unique_input(phase, true);
1808   }
1809   if (uin == top) {             // Simplest case: no alive inputs.
1810     if (can_reshape)            // IGVN transformation
1811       return top;
1812     else
1813       return NULL;              // Identity will return TOP
1814   } else if (uin != NULL) {
1815     // Only one not-NULL unique input path is left.
1816     // Determine if this input is backedge of a loop.
1817     // (Skip new phis which have no uses and dead regions).
1818     if (outcnt() > 0 && r->in(0) != NULL) {
1819       // First, take the short cut when we know it is a loop and
1820       // the EntryControl data path is dead.
1821       // Loop node may have only one input because entry path
1822       // is removed in PhaseIdealLoop::Dominators().
1823       assert(!r->is_Loop() || r->req() <= 3, "Loop node should have 3 or less inputs");
1824       bool is_loop = (r->is_Loop() && r->req() == 3);
1825       // Then, check if there is a data loop when phi references itself directly
1826       // or through other data nodes.
1827       if ((is_loop && !uin->eqv_uncast(in(LoopNode::EntryControl))) ||
1828           (!is_loop && is_unsafe_data_reference(uin))) {
1829         // Break this data loop to avoid creation of a dead loop.
1830         if (can_reshape) {
1831           return top;
1832         } else {
1833           // We can't return top if we are in Parse phase - cut inputs only
1834           // let Identity to handle the case.
1835           replace_edge(uin, top);
1836           return NULL;
1837         }
1838       }
1839     }
1840 
1841     if (uncasted) {
1842       // Add cast nodes between the phi to be removed and its unique input.
1843       // Wait until after parsing for the type information to propagate from the casts.
1844       assert(can_reshape, "Invalid during parsing");
1845       const Type* phi_type = bottom_type();
1846       assert(phi_type->isa_int() || phi_type->isa_ptr(), "bad phi type");
1847       // Add casts to carry the control dependency of the Phi that is
1848       // going away
1849       Node* cast = NULL;
1850       if (phi_type->isa_int()) {
1851         cast = ConstraintCastNode::make_cast(Op_CastII, r, uin, phi_type, true);
1852       } else {
1853         const Type* uin_type = phase->type(uin);
1854         if (!phi_type->isa_oopptr() && !uin_type->isa_oopptr()) {
1855           cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1856         } else {
1857           // Use a CastPP for a cast to not null and a CheckCastPP for
1858           // a cast to a new klass (and both if both null-ness and
1859           // klass change).
1860 
1861           // If the type of phi is not null but the type of uin may be
1862           // null, uin's type must be casted to not null
1863           if (phi_type->join(TypePtr::NOTNULL) == phi_type->remove_speculative() &&
1864               uin_type->join(TypePtr::NOTNULL) != uin_type->remove_speculative()) {
1865             cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, TypePtr::NOTNULL, true);
1866           }
1867 
1868           // If the type of phi and uin, both casted to not null,
1869           // differ the klass of uin must be (check)cast'ed to match
1870           // that of phi
1871           if (phi_type->join_speculative(TypePtr::NOTNULL) != uin_type->join_speculative(TypePtr::NOTNULL)) {
1872             Node* n = uin;
1873             if (cast != NULL) {
1874               cast = phase->transform(cast);
1875               n = cast;
1876             }
1877             cast = ConstraintCastNode::make_cast(Op_CheckCastPP, r, n, phi_type, true);
1878           }
1879           if (cast == NULL) {
1880             cast = ConstraintCastNode::make_cast(Op_CastPP, r, uin, phi_type, true);
1881           }
1882         }
1883       }
1884       assert(cast != NULL, "cast should be set");
1885       cast = phase->transform(cast);
1886       // set all inputs to the new cast(s) so the Phi is removed by Identity
1887       PhaseIterGVN* igvn = phase->is_IterGVN();
1888       for (uint i = 1; i < req(); i++) {
1889         set_req_X(i, cast, igvn);
1890       }
1891       uin = cast;
1892     }
1893 
1894     // One unique input.
1895     debug_only(Node* ident = Identity(phase));
1896     // The unique input must eventually be detected by the Identity call.
1897 #ifdef ASSERT
1898     if (ident != uin && !ident->is_top()) {
1899       // print this output before failing assert
1900       r->dump(3);
1901       this->dump(3);
1902       ident->dump();
1903       uin->dump();
1904     }
1905 #endif
1906     assert(ident == uin || ident->is_top(), "Identity must clean this up");
1907     return NULL;
1908   }
1909 
1910   Node* opt = NULL;
1911   int true_path = is_diamond_phi();
1912   if( true_path != 0 ) {
1913     // Check for CMove'ing identity. If it would be unsafe,
1914     // handle it here. In the safe case, let Identity handle it.
1915     Node* unsafe_id = is_cmove_id(phase, true_path);
1916     if( unsafe_id != NULL && is_unsafe_data_reference(unsafe_id) )
1917       opt = unsafe_id;
1918 
1919     // Check for simple convert-to-boolean pattern
1920     if( opt == NULL )
1921       opt = is_x2logic(phase, this, true_path);
1922 
1923     // Check for absolute value
1924     if( opt == NULL )
1925       opt = is_absolute(phase, this, true_path);
1926 
1927     // Check for conditional add
1928     if( opt == NULL && can_reshape )
1929       opt = is_cond_add(phase, this, true_path);
1930 
1931     // These 4 optimizations could subsume the phi:
1932     // have to check for a dead data loop creation.
1933     if( opt != NULL ) {
1934       if( opt == unsafe_id || is_unsafe_data_reference(opt) ) {
1935         // Found dead loop.
1936         if( can_reshape )
1937           return top;
1938         // We can't return top if we are in Parse phase - cut inputs only
1939         // to stop further optimizations for this phi. Identity will return TOP.
1940         assert(req() == 3, "only diamond merge phi here");
1941         set_req(1, top);
1942         set_req(2, top);
1943         return NULL;
1944       } else {
1945         return opt;
1946       }
1947     }
1948   }
1949 
1950   // Check for merging identical values and split flow paths
1951   if (can_reshape) {
1952     opt = split_flow_path(phase, this);
1953     // This optimization only modifies phi - don't need to check for dead loop.
1954     assert(opt == NULL || phase->eqv(opt, this), "do not elide phi");
1955     if (opt != NULL)  return opt;
1956   }
1957 
1958   if (in(1) != NULL && in(1)->Opcode() == Op_AddP && can_reshape) {
1959     // Try to undo Phi of AddP:
1960     // (Phi (AddP base base y) (AddP base2 base2 y))
1961     // becomes:
1962     // newbase := (Phi base base2)
1963     // (AddP newbase newbase y)
1964     //
1965     // This occurs as a result of unsuccessful split_thru_phi and
1966     // interferes with taking advantage of addressing modes. See the
1967     // clone_shift_expressions code in matcher.cpp
1968     Node* addp = in(1);
1969     const Type* type = addp->in(AddPNode::Base)->bottom_type();
1970     Node* y = addp->in(AddPNode::Offset);
1971     if (y != NULL && addp->in(AddPNode::Base) == addp->in(AddPNode::Address)) {
1972       // make sure that all the inputs are similar to the first one,
1973       // i.e. AddP with base == address and same offset as first AddP
1974       bool doit = true;
1975       for (uint i = 2; i < req(); i++) {
1976         if (in(i) == NULL ||
1977             in(i)->Opcode() != Op_AddP ||
1978             in(i)->in(AddPNode::Base) != in(i)->in(AddPNode::Address) ||
1979             in(i)->in(AddPNode::Offset) != y) {
1980           doit = false;
1981           break;
1982         }
1983         // Accumulate type for resulting Phi
1984         type = type->meet_speculative(in(i)->in(AddPNode::Base)->bottom_type());
1985       }
1986       Node* base = NULL;
1987       if (doit) {
1988         // Check for neighboring AddP nodes in a tree.
1989         // If they have a base, use that it.
1990         for (DUIterator_Fast kmax, k = this->fast_outs(kmax); k < kmax; k++) {
1991           Node* u = this->fast_out(k);
1992           if (u->is_AddP()) {
1993             Node* base2 = u->in(AddPNode::Base);
1994             if (base2 != NULL && !base2->is_top()) {
1995               if (base == NULL)
1996                 base = base2;
1997               else if (base != base2)
1998                 { doit = false; break; }
1999             }
2000           }
2001         }
2002       }
2003       if (doit) {
2004         if (base == NULL) {
2005           base = new PhiNode(in(0), type, NULL);
2006           for (uint i = 1; i < req(); i++) {
2007             base->init_req(i, in(i)->in(AddPNode::Base));
2008           }
2009           phase->is_IterGVN()->register_new_node_with_optimizer(base);
2010         }
2011         return new AddPNode(base, base, y);
2012       }
2013     }
2014   }
2015 
2016   // Split phis through memory merges, so that the memory merges will go away.
2017   // Piggy-back this transformation on the search for a unique input....
2018   // It will be as if the merged memory is the unique value of the phi.
2019   // (Do not attempt this optimization unless parsing is complete.
2020   // It would make the parser's memory-merge logic sick.)
2021   // (MergeMemNode is not dead_loop_safe - need to check for dead loop.)
2022   if (progress == NULL && can_reshape && type() == Type::MEMORY) {
2023     // see if this phi should be sliced
2024     uint merge_width = 0;
2025     bool saw_self = false;
2026     for( uint i=1; i<req(); ++i ) {// For all paths in
2027       Node *ii = in(i);
2028       // TOP inputs should not be counted as safe inputs because if the
2029       // Phi references itself through all other inputs then splitting the
2030       // Phi through memory merges would create dead loop at later stage.
2031       if (ii == top) {
2032         return NULL; // Delay optimization until graph is cleaned.
2033       }
2034       if (ii->is_MergeMem()) {
2035         MergeMemNode* n = ii->as_MergeMem();
2036         merge_width = MAX2(merge_width, n->req());
2037         saw_self = saw_self || phase->eqv(n->base_memory(), this);
2038       }
2039     }
2040 
2041     // This restriction is temporarily necessary to ensure termination:
2042     if (!saw_self && adr_type() == TypePtr::BOTTOM)  merge_width = 0;
2043 
2044     if (merge_width > Compile::AliasIdxRaw) {
2045       // found at least one non-empty MergeMem
2046       const TypePtr* at = adr_type();
2047       if (at != TypePtr::BOTTOM) {
2048         // Patch the existing phi to select an input from the merge:
2049         // Phi:AT1(...MergeMem(m0, m1, m2)...) into
2050         //     Phi:AT1(...m1...)
2051         int alias_idx = phase->C->get_alias_index(at);
2052         for (uint i=1; i<req(); ++i) {
2053           Node *ii = in(i);
2054           if (ii->is_MergeMem()) {
2055             MergeMemNode* n = ii->as_MergeMem();
2056             // compress paths and change unreachable cycles to TOP
2057             // If not, we can update the input infinitely along a MergeMem cycle
2058             // Equivalent code is in MemNode::Ideal_common
2059             Node *m  = phase->transform(n);
2060             if (outcnt() == 0) {  // Above transform() may kill us!
2061               return top;
2062             }
2063             // If transformed to a MergeMem, get the desired slice
2064             // Otherwise the returned node represents memory for every slice
2065             Node *new_mem = (m->is_MergeMem()) ?
2066                              m->as_MergeMem()->memory_at(alias_idx) : m;
2067             // Update input if it is progress over what we have now
2068             if (new_mem != ii) {
2069               set_req(i, new_mem);
2070               progress = this;
2071             }
2072           }
2073         }
2074       } else {
2075         // We know that at least one MergeMem->base_memory() == this
2076         // (saw_self == true). If all other inputs also references this phi
2077         // (directly or through data nodes) - it is dead loop.
2078         bool saw_safe_input = false;
2079         for (uint j = 1; j < req(); ++j) {
2080           Node *n = in(j);
2081           if (n->is_MergeMem() && n->as_MergeMem()->base_memory() == this)
2082             continue;              // skip known cases
2083           if (!is_unsafe_data_reference(n)) {
2084             saw_safe_input = true; // found safe input
2085             break;
2086           }
2087         }
2088         if (!saw_safe_input)
2089           return top; // all inputs reference back to this phi - dead loop
2090 
2091         // Phi(...MergeMem(m0, m1:AT1, m2:AT2)...) into
2092         //     MergeMem(Phi(...m0...), Phi:AT1(...m1...), Phi:AT2(...m2...))
2093         PhaseIterGVN *igvn = phase->is_IterGVN();
2094         Node* hook = new Node(1);
2095         PhiNode* new_base = (PhiNode*) clone();
2096         // Must eagerly register phis, since they participate in loops.
2097         if (igvn) {
2098           igvn->register_new_node_with_optimizer(new_base);
2099           hook->add_req(new_base);
2100         }
2101         MergeMemNode* result = MergeMemNode::make(new_base);
2102         for (uint i = 1; i < req(); ++i) {
2103           Node *ii = in(i);
2104           if (ii->is_MergeMem()) {
2105             MergeMemNode* n = ii->as_MergeMem();
2106             for (MergeMemStream mms(result, n); mms.next_non_empty2(); ) {
2107               // If we have not seen this slice yet, make a phi for it.
2108               bool made_new_phi = false;
2109               if (mms.is_empty()) {
2110                 Node* new_phi = new_base->slice_memory(mms.adr_type(phase->C));
2111                 made_new_phi = true;
2112                 if (igvn) {
2113                   igvn->register_new_node_with_optimizer(new_phi);
2114                   hook->add_req(new_phi);
2115                 }
2116                 mms.set_memory(new_phi);
2117               }
2118               Node* phi = mms.memory();
2119               assert(made_new_phi || phi->in(i) == n, "replace the i-th merge by a slice");
2120               phi->set_req(i, mms.memory2());
2121             }
2122           }
2123         }
2124         // Distribute all self-loops.
2125         { // (Extra braces to hide mms.)
2126           for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2127             Node* phi = mms.memory();
2128             for (uint i = 1; i < req(); ++i) {
2129               if (phi->in(i) == this)  phi->set_req(i, phi);
2130             }
2131           }
2132         }
2133         // now transform the new nodes, and return the mergemem
2134         for (MergeMemStream mms(result); mms.next_non_empty(); ) {
2135           Node* phi = mms.memory();
2136           mms.set_memory(phase->transform(phi));
2137         }
2138         if (igvn) { // Unhook.
2139           igvn->hash_delete(hook);
2140           for (uint i = 1; i < hook->req(); i++) {
2141             hook->set_req(i, NULL);
2142           }
2143         }
2144         // Replace self with the result.
2145         return result;
2146       }
2147     }
2148     //
2149     // Other optimizations on the memory chain
2150     //
2151     const TypePtr* at = adr_type();
2152     for( uint i=1; i<req(); ++i ) {// For all paths in
2153       Node *ii = in(i);
2154       Node *new_in = MemNode::optimize_memory_chain(ii, at, NULL, phase);
2155       if (ii != new_in ) {
2156         set_req(i, new_in);
2157         progress = this;
2158       }
2159     }
2160   }
2161 
2162 #ifdef _LP64
2163   // Push DecodeN/DecodeNKlass down through phi.
2164   // The rest of phi graph will transform by split EncodeP node though phis up.
2165   if ((UseCompressedOops || UseCompressedClassPointers) && can_reshape && progress == NULL) {
2166     bool may_push = true;
2167     bool has_decodeN = false;
2168     bool is_decodeN = false;
2169     for (uint i=1; i<req(); ++i) {// For all paths in
2170       Node *ii = in(i);
2171       if (ii->is_DecodeNarrowPtr() && ii->bottom_type() == bottom_type()) {
2172         // Do optimization if a non dead path exist.
2173         if (ii->in(1)->bottom_type() != Type::TOP) {
2174           has_decodeN = true;
2175           is_decodeN = ii->is_DecodeN();
2176         }
2177       } else if (!ii->is_Phi()) {
2178         may_push = false;
2179       }
2180     }
2181 
2182     if (has_decodeN && may_push) {
2183       PhaseIterGVN *igvn = phase->is_IterGVN();
2184       // Make narrow type for new phi.
2185       const Type* narrow_t;
2186       if (is_decodeN) {
2187         narrow_t = TypeNarrowOop::make(this->bottom_type()->is_ptr());
2188       } else {
2189         narrow_t = TypeNarrowKlass::make(this->bottom_type()->is_ptr());
2190       }
2191       PhiNode* new_phi = new PhiNode(r, narrow_t);
2192       uint orig_cnt = req();
2193       for (uint i=1; i<req(); ++i) {// For all paths in
2194         Node *ii = in(i);
2195         Node* new_ii = NULL;
2196         if (ii->is_DecodeNarrowPtr()) {
2197           assert(ii->bottom_type() == bottom_type(), "sanity");
2198           new_ii = ii->in(1);
2199         } else {
2200           assert(ii->is_Phi(), "sanity");
2201           if (ii->as_Phi() == this) {
2202             new_ii = new_phi;
2203           } else {
2204             if (is_decodeN) {
2205               new_ii = new EncodePNode(ii, narrow_t);
2206             } else {
2207               new_ii = new EncodePKlassNode(ii, narrow_t);
2208             }
2209             igvn->register_new_node_with_optimizer(new_ii);
2210           }
2211         }
2212         new_phi->set_req(i, new_ii);
2213       }
2214       igvn->register_new_node_with_optimizer(new_phi, this);
2215       if (is_decodeN) {
2216         progress = new DecodeNNode(new_phi, bottom_type());
2217       } else {
2218         progress = new DecodeNKlassNode(new_phi, bottom_type());
2219       }
2220     }
2221   }
2222 #endif
2223 
2224   return progress;              // Return any progress
2225 }
2226 
2227 //------------------------------is_tripcount-----------------------------------
2228 bool PhiNode::is_tripcount() const {
2229   return (in(0) != NULL && in(0)->is_CountedLoop() &&
2230           in(0)->as_CountedLoop()->phi() == this);
2231 }
2232 
2233 //------------------------------out_RegMask------------------------------------
2234 const RegMask &PhiNode::in_RegMask(uint i) const {
2235   return i ? out_RegMask() : RegMask::Empty;
2236 }
2237 
2238 const RegMask &PhiNode::out_RegMask() const {
2239   uint ideal_reg = _type->ideal_reg();
2240   assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
2241   if( ideal_reg == 0 ) return RegMask::Empty;
2242   assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
2243   return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
2244 }
2245 
2246 #ifndef PRODUCT
2247 void PhiNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2248   // For a PhiNode, the set of related nodes includes all inputs till level 2,
2249   // and all outputs till level 1. In compact mode, inputs till level 1 are
2250   // collected.
2251   this->collect_nodes(in_rel, compact ? 1 : 2, false, false);
2252   this->collect_nodes(out_rel, -1, false, false);
2253 }
2254 
2255 void PhiNode::dump_spec(outputStream *st) const {
2256   TypeNode::dump_spec(st);
2257   if (is_tripcount()) {
2258     st->print(" #tripcount");
2259   }
2260 }
2261 #endif
2262 
2263 
2264 //=============================================================================
2265 const Type* GotoNode::Value(PhaseGVN* phase) const {
2266   // If the input is reachable, then we are executed.
2267   // If the input is not reachable, then we are not executed.
2268   return phase->type(in(0));
2269 }
2270 
2271 Node* GotoNode::Identity(PhaseGVN* phase) {
2272   return in(0);                // Simple copy of incoming control
2273 }
2274 
2275 const RegMask &GotoNode::out_RegMask() const {
2276   return RegMask::Empty;
2277 }
2278 
2279 #ifndef PRODUCT
2280 //-----------------------------related-----------------------------------------
2281 // The related nodes of a GotoNode are all inputs at level 1, as well as the
2282 // outputs at level 1. This is regardless of compact mode.
2283 void GotoNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2284   this->collect_nodes(in_rel, 1, false, false);
2285   this->collect_nodes(out_rel, -1, false, false);
2286 }
2287 #endif
2288 
2289 
2290 //=============================================================================
2291 const RegMask &JumpNode::out_RegMask() const {
2292   return RegMask::Empty;
2293 }
2294 
2295 #ifndef PRODUCT
2296 //-----------------------------related-----------------------------------------
2297 // The related nodes of a JumpNode are all inputs at level 1, as well as the
2298 // outputs at level 2 (to include actual jump targets beyond projection nodes).
2299 // This is regardless of compact mode.
2300 void JumpNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2301   this->collect_nodes(in_rel, 1, false, false);
2302   this->collect_nodes(out_rel, -2, false, false);
2303 }
2304 #endif
2305 
2306 //=============================================================================
2307 const RegMask &JProjNode::out_RegMask() const {
2308   return RegMask::Empty;
2309 }
2310 
2311 //=============================================================================
2312 const RegMask &CProjNode::out_RegMask() const {
2313   return RegMask::Empty;
2314 }
2315 
2316 
2317 
2318 //=============================================================================
2319 
2320 uint PCTableNode::hash() const { return Node::hash() + _size; }
2321 uint PCTableNode::cmp( const Node &n ) const
2322 { return _size == ((PCTableNode&)n)._size; }
2323 
2324 const Type *PCTableNode::bottom_type() const {
2325   const Type** f = TypeTuple::fields(_size);
2326   for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2327   return TypeTuple::make(_size, f);
2328 }
2329 
2330 //------------------------------Value------------------------------------------
2331 // Compute the type of the PCTableNode.  If reachable it is a tuple of
2332 // Control, otherwise the table targets are not reachable
2333 const Type* PCTableNode::Value(PhaseGVN* phase) const {
2334   if( phase->type(in(0)) == Type::CONTROL )
2335     return bottom_type();
2336   return Type::TOP;             // All paths dead?  Then so are we
2337 }
2338 
2339 //------------------------------Ideal------------------------------------------
2340 // Return a node which is more "ideal" than the current node.  Strip out
2341 // control copies
2342 Node *PCTableNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2343   return remove_dead_region(phase, can_reshape) ? this : NULL;
2344 }
2345 
2346 //=============================================================================
2347 uint JumpProjNode::hash() const {
2348   return Node::hash() + _dest_bci;
2349 }
2350 
2351 uint JumpProjNode::cmp( const Node &n ) const {
2352   return ProjNode::cmp(n) &&
2353     _dest_bci == ((JumpProjNode&)n)._dest_bci;
2354 }
2355 
2356 #ifndef PRODUCT
2357 void JumpProjNode::dump_spec(outputStream *st) const {
2358   ProjNode::dump_spec(st);
2359   st->print("@bci %d ",_dest_bci);
2360 }
2361 
2362 void JumpProjNode::dump_compact_spec(outputStream *st) const {
2363   ProjNode::dump_compact_spec(st);
2364   st->print("(%d)%d@%d", _switch_val, _proj_no, _dest_bci);
2365 }
2366 
2367 void JumpProjNode::related(GrowableArray<Node*> *in_rel, GrowableArray<Node*> *out_rel, bool compact) const {
2368   // The related nodes of a JumpProjNode are its inputs and outputs at level 1.
2369   this->collect_nodes(in_rel, 1, false, false);
2370   this->collect_nodes(out_rel, -1, false, false);
2371 }
2372 #endif
2373 
2374 //=============================================================================
2375 //------------------------------Value------------------------------------------
2376 // Check for being unreachable, or for coming from a Rethrow.  Rethrow's cannot
2377 // have the default "fall_through_index" path.
2378 const Type* CatchNode::Value(PhaseGVN* phase) const {
2379   // Unreachable?  Then so are all paths from here.
2380   if( phase->type(in(0)) == Type::TOP ) return Type::TOP;
2381   // First assume all paths are reachable
2382   const Type** f = TypeTuple::fields(_size);
2383   for( uint i = 0; i < _size; i++ ) f[i] = Type::CONTROL;
2384   // Identify cases that will always throw an exception
2385   // () rethrow call
2386   // () virtual or interface call with NULL receiver
2387   // () call is a check cast with incompatible arguments
2388   if( in(1)->is_Proj() ) {
2389     Node *i10 = in(1)->in(0);
2390     if( i10->is_Call() ) {
2391       CallNode *call = i10->as_Call();
2392       // Rethrows always throw exceptions, never return
2393       if (call->entry_point() == OptoRuntime::rethrow_stub()) {
2394         f[CatchProjNode::fall_through_index] = Type::TOP;
2395       } else if( call->req() > TypeFunc::Parms ) {
2396         const Type *arg0 = phase->type( call->in(TypeFunc::Parms) );
2397         // Check for null receiver to virtual or interface calls
2398         if( call->is_CallDynamicJava() &&
2399             arg0->higher_equal(TypePtr::NULL_PTR) ) {
2400           f[CatchProjNode::fall_through_index] = Type::TOP;
2401         }
2402       } // End of if not a runtime stub
2403     } // End of if have call above me
2404   } // End of slot 1 is not a projection
2405   return TypeTuple::make(_size, f);
2406 }
2407 
2408 //=============================================================================
2409 uint CatchProjNode::hash() const {
2410   return Node::hash() + _handler_bci;
2411 }
2412 
2413 
2414 uint CatchProjNode::cmp( const Node &n ) const {
2415   return ProjNode::cmp(n) &&
2416     _handler_bci == ((CatchProjNode&)n)._handler_bci;
2417 }
2418 
2419 
2420 //------------------------------Identity---------------------------------------
2421 // If only 1 target is possible, choose it if it is the main control
2422 Node* CatchProjNode::Identity(PhaseGVN* phase) {
2423   // If my value is control and no other value is, then treat as ID
2424   const TypeTuple *t = phase->type(in(0))->is_tuple();
2425   if (t->field_at(_con) != Type::CONTROL)  return this;
2426   // If we remove the last CatchProj and elide the Catch/CatchProj, then we
2427   // also remove any exception table entry.  Thus we must know the call
2428   // feeding the Catch will not really throw an exception.  This is ok for
2429   // the main fall-thru control (happens when we know a call can never throw
2430   // an exception) or for "rethrow", because a further optimization will
2431   // yank the rethrow (happens when we inline a function that can throw an
2432   // exception and the caller has no handler).  Not legal, e.g., for passing
2433   // a NULL receiver to a v-call, or passing bad types to a slow-check-cast.
2434   // These cases MUST throw an exception via the runtime system, so the VM
2435   // will be looking for a table entry.
2436   Node *proj = in(0)->in(1);    // Expect a proj feeding CatchNode
2437   CallNode *call;
2438   if (_con != TypeFunc::Control && // Bail out if not the main control.
2439       !(proj->is_Proj() &&      // AND NOT a rethrow
2440         proj->in(0)->is_Call() &&
2441         (call = proj->in(0)->as_Call()) &&
2442         call->entry_point() == OptoRuntime::rethrow_stub()))
2443     return this;
2444 
2445   // Search for any other path being control
2446   for (uint i = 0; i < t->cnt(); i++) {
2447     if (i != _con && t->field_at(i) == Type::CONTROL)
2448       return this;
2449   }
2450   // Only my path is possible; I am identity on control to the jump
2451   return in(0)->in(0);
2452 }
2453 
2454 
2455 #ifndef PRODUCT
2456 void CatchProjNode::dump_spec(outputStream *st) const {
2457   ProjNode::dump_spec(st);
2458   st->print("@bci %d ",_handler_bci);
2459 }
2460 #endif
2461 
2462 //=============================================================================
2463 //------------------------------Identity---------------------------------------
2464 // Check for CreateEx being Identity.
2465 Node* CreateExNode::Identity(PhaseGVN* phase) {
2466   if( phase->type(in(1)) == Type::TOP ) return in(1);
2467   if( phase->type(in(0)) == Type::TOP ) return in(0);
2468   // We only come from CatchProj, unless the CatchProj goes away.
2469   // If the CatchProj is optimized away, then we just carry the
2470   // exception oop through.
2471   CallNode *call = in(1)->in(0)->as_Call();
2472 
2473   return ( in(0)->is_CatchProj() && in(0)->in(0)->in(1) == in(1) )
2474     ? this
2475     : call->in(TypeFunc::Parms);
2476 }
2477 
2478 //=============================================================================
2479 //------------------------------Value------------------------------------------
2480 // Check for being unreachable.
2481 const Type* NeverBranchNode::Value(PhaseGVN* phase) const {
2482   if (!in(0) || in(0)->is_top()) return Type::TOP;
2483   return bottom_type();
2484 }
2485 
2486 //------------------------------Ideal------------------------------------------
2487 // Check for no longer being part of a loop
2488 Node *NeverBranchNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2489   if (can_reshape && !in(0)->is_Loop()) {
2490     // Dead code elimination can sometimes delete this projection so
2491     // if it's not there, there's nothing to do.
2492     Node* fallthru = proj_out_or_null(0);
2493     if (fallthru != NULL) {
2494       phase->is_IterGVN()->replace_node(fallthru, in(0));
2495     }
2496     return phase->C->top();
2497   }
2498   return NULL;
2499 }
2500 
2501 #ifndef PRODUCT
2502 void NeverBranchNode::format( PhaseRegAlloc *ra_, outputStream *st) const {
2503   st->print("%s", Name());
2504 }
2505 #endif