1 /*
   2  * Copyright (c) 1998, 2014, 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 "memory/allocation.inline.hpp"
  27 #include "opto/ad.hpp"
  28 #include "opto/block.hpp"
  29 #include "opto/c2compiler.hpp"
  30 #include "opto/callnode.hpp"
  31 #include "opto/cfgnode.hpp"
  32 #include "opto/machnode.hpp"
  33 #include "opto/runtime.hpp"
  34 #include "runtime/sharedRuntime.hpp"
  35 
  36 // Optimization - Graph Style
  37 
  38 // Check whether val is not-null-decoded compressed oop,
  39 // i.e. will grab into the base of the heap if it represents NULL.
  40 static bool accesses_heap_base_zone(Node *val) {
  41   if (Universe::narrow_oop_base() > 0) { // Implies UseCompressedOops.
  42     if (val && val->is_Mach()) {
  43       if (val->as_Mach()->ideal_Opcode() == Op_DecodeN) {
  44         // This assumes all Decodes with TypePtr::NotNull are matched to nodes that
  45         // decode NULL to point to the heap base (Decode_NN).
  46         if (val->bottom_type()->is_oopptr()->ptr() == TypePtr::NotNull) {
  47           return true;
  48         }
  49       }
  50       // Must recognize load operation with Decode matched in memory operand.
  51       // We should not reach here exept for PPC/AIX, as os::zero_page_read_protected()
  52       // returns true everywhere else. On PPC, no such memory operands
  53       // exist, therefore we did not yet implement a check for such operands.
  54       NOT_AIX(Unimplemented());
  55     }
  56   }
  57   return false;
  58 }
  59 
  60 static bool needs_explicit_null_check_for_read(Node *val) {
  61   // On some OSes (AIX) the page at address 0 is only write protected.
  62   // If so, only Store operations will trap.
  63   if (os::zero_page_read_protected()) {
  64     return false;  // Implicit null check will work.
  65   }
  66   // Also a read accessing the base of a heap-based compressed heap will trap.
  67   if (accesses_heap_base_zone(val) &&                    // Hits the base zone page.
  68       Universe::narrow_oop_use_implicit_null_checks()) { // Base zone page is protected.
  69     return false;
  70   }
  71 
  72   return true;
  73 }
  74 
  75 //------------------------------implicit_null_check----------------------------
  76 // Detect implicit-null-check opportunities.  Basically, find NULL checks
  77 // with suitable memory ops nearby.  Use the memory op to do the NULL check.
  78 // I can generate a memory op if there is not one nearby.
  79 // The proj is the control projection for the not-null case.
  80 // The val is the pointer being checked for nullness or
  81 // decodeHeapOop_not_null node if it did not fold into address.
  82 void PhaseCFG::implicit_null_check(Block* block, Node *proj, Node *val, int allowed_reasons) {
  83   // Assume if null check need for 0 offset then always needed
  84   // Intel solaris doesn't support any null checks yet and no
  85   // mechanism exists (yet) to set the switches at an os_cpu level
  86   if( !ImplicitNullChecks || MacroAssembler::needs_explicit_null_check(0)) return;
  87 
  88   // Make sure the ptr-is-null path appears to be uncommon!
  89   float f = block->end()->as_MachIf()->_prob;
  90   if( proj->Opcode() == Op_IfTrue ) f = 1.0f - f;
  91   if( f > PROB_UNLIKELY_MAG(4) ) return;
  92 
  93   uint bidx = 0;                // Capture index of value into memop
  94   bool was_store;               // Memory op is a store op
  95 
  96   // Get the successor block for if the test ptr is non-null
  97   Block* not_null_block;  // this one goes with the proj
  98   Block* null_block;
  99   if (block->get_node(block->number_of_nodes()-1) == proj) {
 100     null_block     = block->_succs[0];
 101     not_null_block = block->_succs[1];
 102   } else {
 103     assert(block->get_node(block->number_of_nodes()-2) == proj, "proj is one or the other");
 104     not_null_block = block->_succs[0];
 105     null_block     = block->_succs[1];
 106   }
 107   while (null_block->is_Empty() == Block::empty_with_goto) {
 108     null_block     = null_block->_succs[0];
 109   }
 110 
 111   // Search the exception block for an uncommon trap.
 112   // (See Parse::do_if and Parse::do_ifnull for the reason
 113   // we need an uncommon trap.  Briefly, we need a way to
 114   // detect failure of this optimization, as in 6366351.)
 115   {
 116     bool found_trap = false;
 117     for (uint i1 = 0; i1 < null_block->number_of_nodes(); i1++) {
 118       Node* nn = null_block->get_node(i1);
 119       if (nn->is_MachCall() &&
 120           nn->as_MachCall()->entry_point() == SharedRuntime::uncommon_trap_blob()->entry_point()) {
 121         const Type* trtype = nn->in(TypeFunc::Parms)->bottom_type();
 122         if (trtype->isa_int() && trtype->is_int()->is_con()) {
 123           jint tr_con = trtype->is_int()->get_con();
 124           Deoptimization::DeoptReason reason = Deoptimization::trap_request_reason(tr_con);
 125           Deoptimization::DeoptAction action = Deoptimization::trap_request_action(tr_con);
 126           assert((int)reason < (int)BitsPerInt, "recode bit map");
 127           if (is_set_nth_bit(allowed_reasons, (int) reason)
 128               && action != Deoptimization::Action_none) {
 129             // This uncommon trap is sure to recompile, eventually.
 130             // When that happens, C->too_many_traps will prevent
 131             // this transformation from happening again.
 132             found_trap = true;
 133           }
 134         }
 135         break;
 136       }
 137     }
 138     if (!found_trap) {
 139       // We did not find an uncommon trap.
 140       return;
 141     }
 142   }
 143 
 144   // Check for decodeHeapOop_not_null node which did not fold into address
 145   bool is_decoden = ((intptr_t)val) & 1;
 146   val = (Node*)(((intptr_t)val) & ~1);
 147 
 148   assert(!is_decoden || (val->in(0) == NULL) && val->is_Mach() &&
 149          (val->as_Mach()->ideal_Opcode() == Op_DecodeN), "sanity");
 150 
 151   // Search the successor block for a load or store who's base value is also
 152   // the tested value.  There may be several.
 153   Node_List *out = new Node_List(Thread::current()->resource_area());
 154   MachNode *best = NULL;        // Best found so far
 155   for (DUIterator i = val->outs(); val->has_out(i); i++) {
 156     Node *m = val->out(i);
 157     if( !m->is_Mach() ) continue;
 158     MachNode *mach = m->as_Mach();
 159     was_store = false;
 160     int iop = mach->ideal_Opcode();
 161     switch( iop ) {
 162     case Op_LoadB:
 163     case Op_LoadUB:
 164     case Op_LoadUS:
 165     case Op_LoadD:
 166     case Op_LoadF:
 167     case Op_LoadI:
 168     case Op_LoadL:
 169     case Op_LoadP:
 170     case Op_LoadN:
 171     case Op_LoadS:
 172     case Op_LoadKlass:
 173     case Op_LoadNKlass:
 174     case Op_LoadRange:
 175     case Op_LoadD_unaligned:
 176     case Op_LoadL_unaligned:
 177       assert(mach->in(2) == val, "should be address");
 178       break;
 179     case Op_StoreB:
 180     case Op_StoreC:
 181     case Op_StoreCM:
 182     case Op_StoreD:
 183     case Op_StoreF:
 184     case Op_StoreI:
 185     case Op_StoreL:
 186     case Op_StoreP:
 187     case Op_StoreN:
 188     case Op_StoreNKlass:
 189       was_store = true;         // Memory op is a store op
 190       // Stores will have their address in slot 2 (memory in slot 1).
 191       // If the value being nul-checked is in another slot, it means we
 192       // are storing the checked value, which does NOT check the value!
 193       if( mach->in(2) != val ) continue;
 194       break;                    // Found a memory op?
 195     case Op_StrComp:
 196     case Op_StrEquals:
 197     case Op_StrIndexOf:
 198     case Op_AryEq:
 199     case Op_EncodeISOArray:
 200       // Not a legit memory op for implicit null check regardless of
 201       // embedded loads
 202       continue;
 203     default:                    // Also check for embedded loads
 204       if( !mach->needs_anti_dependence_check() )
 205         continue;               // Not an memory op; skip it
 206       if( must_clone[iop] ) {
 207         // Do not move nodes which produce flags because
 208         // RA will try to clone it to place near branch and
 209         // it will cause recompilation, see clone_node().
 210         continue;
 211       }
 212       {
 213         // Check that value is used in memory address in
 214         // instructions with embedded load (CmpP val1,(val2+off)).
 215         Node* base;
 216         Node* index;
 217         const MachOper* oper = mach->memory_inputs(base, index);
 218         if (oper == NULL || oper == (MachOper*)-1) {
 219           continue;             // Not an memory op; skip it
 220         }
 221         if (val == base ||
 222             val == index && val->bottom_type()->isa_narrowoop()) {
 223           break;                // Found it
 224         } else {
 225           continue;             // Skip it
 226         }
 227       }
 228       break;
 229     }
 230 
 231     // On some OSes (AIX) the page at address 0 is only write protected.
 232     // If so, only Store operations will trap.
 233     // But a read accessing the base of a heap-based compressed heap will trap.
 234     if (!was_store && needs_explicit_null_check_for_read(val)) {
 235       continue;
 236     }
 237 
 238     // check if the offset is not too high for implicit exception
 239     {
 240       intptr_t offset = 0;
 241       const TypePtr *adr_type = NULL;  // Do not need this return value here
 242       const Node* base = mach->get_base_and_disp(offset, adr_type);
 243       if (base == NULL || base == NodeSentinel) {
 244         // Narrow oop address doesn't have base, only index
 245         if( val->bottom_type()->isa_narrowoop() &&
 246             MacroAssembler::needs_explicit_null_check(offset) )
 247           continue;             // Give up if offset is beyond page size
 248         // cannot reason about it; is probably not implicit null exception
 249       } else {
 250         const TypePtr* tptr;
 251         if (UseCompressedOops && (Universe::narrow_oop_shift() == 0 ||
 252                                   Universe::narrow_klass_shift() == 0)) {
 253           // 32-bits narrow oop can be the base of address expressions
 254           tptr = base->get_ptr_type();
 255         } else {
 256           // only regular oops are expected here
 257           tptr = base->bottom_type()->is_ptr();
 258         }
 259         // Give up if offset is not a compile-time constant
 260         if( offset == Type::OffsetBot || tptr->_offset == Type::OffsetBot )
 261           continue;
 262         offset += tptr->_offset; // correct if base is offseted
 263         if( MacroAssembler::needs_explicit_null_check(offset) )
 264           continue;             // Give up is reference is beyond 4K page size
 265       }
 266     }
 267 
 268     // Check ctrl input to see if the null-check dominates the memory op
 269     Block *cb = get_block_for_node(mach);
 270     cb = cb->_idom;             // Always hoist at least 1 block
 271     if( !was_store ) {          // Stores can be hoisted only one block
 272       while( cb->_dom_depth > (block->_dom_depth + 1))
 273         cb = cb->_idom;         // Hoist loads as far as we want
 274       // The non-null-block should dominate the memory op, too. Live
 275       // range spilling will insert a spill in the non-null-block if it is
 276       // needs to spill the memory op for an implicit null check.
 277       if (cb->_dom_depth == (block->_dom_depth + 1)) {
 278         if (cb != not_null_block) continue;
 279         cb = cb->_idom;
 280       }
 281     }
 282     if( cb != block ) continue;
 283 
 284     // Found a memory user; see if it can be hoisted to check-block
 285     uint vidx = 0;              // Capture index of value into memop
 286     uint j;
 287     for( j = mach->req()-1; j > 0; j-- ) {
 288       if( mach->in(j) == val ) {
 289         vidx = j;
 290         // Ignore DecodeN val which could be hoisted to where needed.
 291         if( is_decoden ) continue;
 292       }
 293       // Block of memory-op input
 294       Block *inb = get_block_for_node(mach->in(j));
 295       Block *b = block;          // Start from nul check
 296       while( b != inb && b->_dom_depth > inb->_dom_depth )
 297         b = b->_idom;           // search upwards for input
 298       // See if input dominates null check
 299       if( b != inb )
 300         break;
 301     }
 302     if( j > 0 )
 303       continue;
 304     Block *mb = get_block_for_node(mach);
 305     // Hoisting stores requires more checks for the anti-dependence case.
 306     // Give up hoisting if we have to move the store past any load.
 307     if( was_store ) {
 308       Block *b = mb;            // Start searching here for a local load
 309       // mach use (faulting) trying to hoist
 310       // n might be blocker to hoisting
 311       while( b != block ) {
 312         uint k;
 313         for( k = 1; k < b->number_of_nodes(); k++ ) {
 314           Node *n = b->get_node(k);
 315           if( n->needs_anti_dependence_check() &&
 316               n->in(LoadNode::Memory) == mach->in(StoreNode::Memory) )
 317             break;              // Found anti-dependent load
 318         }
 319         if( k < b->number_of_nodes() )
 320           break;                // Found anti-dependent load
 321         // Make sure control does not do a merge (would have to check allpaths)
 322         if( b->num_preds() != 2 ) break;
 323         b = get_block_for_node(b->pred(1)); // Move up to predecessor block
 324       }
 325       if( b != block ) continue;
 326     }
 327 
 328     // Make sure this memory op is not already being used for a NullCheck
 329     Node *e = mb->end();
 330     if( e->is_MachNullCheck() && e->in(1) == mach )
 331       continue;                 // Already being used as a NULL check
 332 
 333     // Found a candidate!  Pick one with least dom depth - the highest
 334     // in the dom tree should be closest to the null check.
 335     if (best == NULL || get_block_for_node(mach)->_dom_depth < get_block_for_node(best)->_dom_depth) {
 336       best = mach;
 337       bidx = vidx;
 338     }
 339   }
 340   // No candidate!
 341   if (best == NULL) {
 342     return;
 343   }
 344 
 345   // ---- Found an implicit null check
 346   extern int implicit_null_checks;
 347   implicit_null_checks++;
 348 
 349   if( is_decoden ) {
 350     // Check if we need to hoist decodeHeapOop_not_null first.
 351     Block *valb = get_block_for_node(val);
 352     if( block != valb && block->_dom_depth < valb->_dom_depth ) {
 353       // Hoist it up to the end of the test block.
 354       valb->find_remove(val);
 355       block->add_inst(val);
 356       map_node_to_block(val, block);
 357       // DecodeN on x86 may kill flags. Check for flag-killing projections
 358       // that also need to be hoisted.
 359       for (DUIterator_Fast jmax, j = val->fast_outs(jmax); j < jmax; j++) {
 360         Node* n = val->fast_out(j);
 361         if( n->is_MachProj() ) {
 362           get_block_for_node(n)->find_remove(n);
 363           block->add_inst(n);
 364           map_node_to_block(n, block);
 365         }
 366       }
 367     }
 368   }
 369   // Hoist the memory candidate up to the end of the test block.
 370   Block *old_block = get_block_for_node(best);
 371   old_block->find_remove(best);
 372   block->add_inst(best);
 373   map_node_to_block(best, block);
 374 
 375   // Move the control dependence
 376   if (best->in(0) && best->in(0) == old_block->head())
 377     best->set_req(0, block->head());
 378 
 379   // Check for flag-killing projections that also need to be hoisted
 380   // Should be DU safe because no edge updates.
 381   for (DUIterator_Fast jmax, j = best->fast_outs(jmax); j < jmax; j++) {
 382     Node* n = best->fast_out(j);
 383     if( n->is_MachProj() ) {
 384       get_block_for_node(n)->find_remove(n);
 385       block->add_inst(n);
 386       map_node_to_block(n, block);
 387     }
 388   }
 389 
 390   // proj==Op_True --> ne test; proj==Op_False --> eq test.
 391   // One of two graph shapes got matched:
 392   //   (IfTrue  (If (Bool NE (CmpP ptr NULL))))
 393   //   (IfFalse (If (Bool EQ (CmpP ptr NULL))))
 394   // NULL checks are always branch-if-eq.  If we see a IfTrue projection
 395   // then we are replacing a 'ne' test with a 'eq' NULL check test.
 396   // We need to flip the projections to keep the same semantics.
 397   if( proj->Opcode() == Op_IfTrue ) {
 398     // Swap order of projections in basic block to swap branch targets
 399     Node *tmp1 = block->get_node(block->end_idx()+1);
 400     Node *tmp2 = block->get_node(block->end_idx()+2);
 401     block->map_node(tmp2, block->end_idx()+1);
 402     block->map_node(tmp1, block->end_idx()+2);
 403     Node *tmp = new Node(C->top()); // Use not NULL input
 404     tmp1->replace_by(tmp);
 405     tmp2->replace_by(tmp1);
 406     tmp->replace_by(tmp2);
 407     tmp->destruct();
 408   }
 409 
 410   // Remove the existing null check; use a new implicit null check instead.
 411   // Since schedule-local needs precise def-use info, we need to correct
 412   // it as well.
 413   Node *old_tst = proj->in(0);
 414   MachNode *nul_chk = new MachNullCheckNode(old_tst->in(0),best,bidx);
 415   block->map_node(nul_chk, block->end_idx());
 416   map_node_to_block(nul_chk, block);
 417   // Redirect users of old_test to nul_chk
 418   for (DUIterator_Last i2min, i2 = old_tst->last_outs(i2min); i2 >= i2min; --i2)
 419     old_tst->last_out(i2)->set_req(0, nul_chk);
 420   // Clean-up any dead code
 421   for (uint i3 = 0; i3 < old_tst->req(); i3++) {
 422     Node* in = old_tst->in(i3);
 423     old_tst->set_req(i3, NULL);
 424     if (in->outcnt() == 0) {
 425       // Remove dead input node
 426       in->disconnect_inputs(NULL, C);
 427       block->find_remove(in);
 428     }
 429   }
 430 
 431   latency_from_uses(nul_chk);
 432   latency_from_uses(best);
 433 }
 434 
 435 
 436 //------------------------------select-----------------------------------------
 437 // Select a nice fellow from the worklist to schedule next. If there is only
 438 // one choice, then use it. Projections take top priority for correctness
 439 // reasons - if I see a projection, then it is next.  There are a number of
 440 // other special cases, for instructions that consume condition codes, et al.
 441 // These are chosen immediately. Some instructions are required to immediately
 442 // precede the last instruction in the block, and these are taken last. Of the
 443 // remaining cases (most), choose the instruction with the greatest latency
 444 // (that is, the most number of pseudo-cycles required to the end of the
 445 // routine). If there is a tie, choose the instruction with the most inputs.
 446 Node* PhaseCFG::select(Block* block, Node_List &worklist, GrowableArray<int> &ready_cnt, VectorSet &next_call, uint sched_slot) {
 447 
 448   // If only a single entry on the stack, use it
 449   uint cnt = worklist.size();
 450   if (cnt == 1) {
 451     Node *n = worklist[0];
 452     worklist.map(0,worklist.pop());
 453     return n;
 454   }
 455 
 456   uint choice  = 0; // Bigger is most important
 457   uint latency = 0; // Bigger is scheduled first
 458   uint score   = 0; // Bigger is better
 459   int idx = -1;     // Index in worklist
 460   int cand_cnt = 0; // Candidate count
 461 
 462   for( uint i=0; i<cnt; i++ ) { // Inspect entire worklist
 463     // Order in worklist is used to break ties.
 464     // See caller for how this is used to delay scheduling
 465     // of induction variable increments to after the other
 466     // uses of the phi are scheduled.
 467     Node *n = worklist[i];      // Get Node on worklist
 468 
 469     int iop = n->is_Mach() ? n->as_Mach()->ideal_Opcode() : 0;
 470     if( n->is_Proj() ||         // Projections always win
 471         n->Opcode()== Op_Con || // So does constant 'Top'
 472         iop == Op_CreateEx ||   // Create-exception must start block
 473         iop == Op_CheckCastPP
 474         ) {
 475       worklist.map(i,worklist.pop());
 476       return n;
 477     }
 478 
 479     // Final call in a block must be adjacent to 'catch'
 480     Node *e = block->end();
 481     if( e->is_Catch() && e->in(0)->in(0) == n )
 482       continue;
 483 
 484     // Memory op for an implicit null check has to be at the end of the block
 485     if( e->is_MachNullCheck() && e->in(1) == n )
 486       continue;
 487 
 488     // Schedule IV increment last.
 489     if (e->is_Mach() && e->as_Mach()->ideal_Opcode() == Op_CountedLoopEnd &&
 490         e->in(1)->in(1) == n && n->is_iteratively_computed())
 491       continue;
 492 
 493     uint n_choice  = 2;
 494 
 495     // See if this instruction is consumed by a branch. If so, then (as the
 496     // branch is the last instruction in the basic block) force it to the
 497     // end of the basic block
 498     if ( must_clone[iop] ) {
 499       // See if any use is a branch
 500       bool found_machif = false;
 501 
 502       for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
 503         Node* use = n->fast_out(j);
 504 
 505         // The use is a conditional branch, make them adjacent
 506         if (use->is_MachIf() && get_block_for_node(use) == block) {
 507           found_machif = true;
 508           break;
 509         }
 510 
 511         // More than this instruction pending for successor to be ready,
 512         // don't choose this if other opportunities are ready
 513         if (ready_cnt.at(use->_idx) > 1)
 514           n_choice = 1;
 515       }
 516 
 517       // loop terminated, prefer not to use this instruction
 518       if (found_machif)
 519         continue;
 520     }
 521 
 522     // See if this has a predecessor that is "must_clone", i.e. sets the
 523     // condition code. If so, choose this first
 524     for (uint j = 0; j < n->req() ; j++) {
 525       Node *inn = n->in(j);
 526       if (inn) {
 527         if (inn->is_Mach() && must_clone[inn->as_Mach()->ideal_Opcode()] ) {
 528           n_choice = 3;
 529           break;
 530         }
 531       }
 532     }
 533 
 534     // MachTemps should be scheduled last so they are near their uses
 535     if (n->is_MachTemp()) {
 536       n_choice = 1;
 537     }
 538 
 539     uint n_latency = get_latency_for_node(n);
 540     uint n_score   = n->req();   // Many inputs get high score to break ties
 541 
 542     // Keep best latency found
 543     cand_cnt++;
 544     if (choice < n_choice ||
 545         (choice == n_choice &&
 546          ((StressLCM && Compile::randomized_select(cand_cnt)) ||
 547           (!StressLCM &&
 548            (latency < n_latency ||
 549             (latency == n_latency &&
 550              (score < n_score))))))) {
 551       choice  = n_choice;
 552       latency = n_latency;
 553       score   = n_score;
 554       idx     = i;               // Also keep index in worklist
 555     }
 556   } // End of for all ready nodes in worklist
 557 
 558   assert(idx >= 0, "index should be set");
 559   Node *n = worklist[(uint)idx];      // Get the winner
 560 
 561   worklist.map((uint)idx, worklist.pop());     // Compress worklist
 562   return n;
 563 }
 564 
 565 
 566 //------------------------------set_next_call----------------------------------
 567 void PhaseCFG::set_next_call(Block* block, Node* n, VectorSet& next_call) {
 568   if( next_call.test_set(n->_idx) ) return;
 569   for( uint i=0; i<n->len(); i++ ) {
 570     Node *m = n->in(i);
 571     if( !m ) continue;  // must see all nodes in block that precede call
 572     if (get_block_for_node(m) == block) {
 573       set_next_call(block, m, next_call);
 574     }
 575   }
 576 }
 577 
 578 //------------------------------needed_for_next_call---------------------------
 579 // Set the flag 'next_call' for each Node that is needed for the next call to
 580 // be scheduled.  This flag lets me bias scheduling so Nodes needed for the
 581 // next subroutine call get priority - basically it moves things NOT needed
 582 // for the next call till after the call.  This prevents me from trying to
 583 // carry lots of stuff live across a call.
 584 void PhaseCFG::needed_for_next_call(Block* block, Node* this_call, VectorSet& next_call) {
 585   // Find the next control-defining Node in this block
 586   Node* call = NULL;
 587   for (DUIterator_Fast imax, i = this_call->fast_outs(imax); i < imax; i++) {
 588     Node* m = this_call->fast_out(i);
 589     if (get_block_for_node(m) == block && // Local-block user
 590         m != this_call &&       // Not self-start node
 591         m->is_MachCall()) {
 592       call = m;
 593       break;
 594     }
 595   }
 596   if (call == NULL)  return;    // No next call (e.g., block end is near)
 597   // Set next-call for all inputs to this call
 598   set_next_call(block, call, next_call);
 599 }
 600 
 601 //------------------------------add_call_kills-------------------------------------
 602 // helper function that adds caller save registers to MachProjNode
 603 static void add_call_kills(MachProjNode *proj, RegMask& regs, const char* save_policy, bool exclude_soe) {
 604   // Fill in the kill mask for the call
 605   for( OptoReg::Name r = OptoReg::Name(0); r < _last_Mach_Reg; r=OptoReg::add(r,1) ) {
 606     if( !regs.Member(r) ) {     // Not already defined by the call
 607       // Save-on-call register?
 608       if ((save_policy[r] == 'C') ||
 609           (save_policy[r] == 'A') ||
 610           ((save_policy[r] == 'E') && exclude_soe)) {
 611         proj->_rout.Insert(r);
 612       }
 613     }
 614   }
 615 }
 616 
 617 
 618 //------------------------------sched_call-------------------------------------
 619 uint PhaseCFG::sched_call(Block* block, uint node_cnt, Node_List& worklist, GrowableArray<int>& ready_cnt, MachCallNode* mcall, VectorSet& next_call) {
 620   RegMask regs;
 621 
 622   // Schedule all the users of the call right now.  All the users are
 623   // projection Nodes, so they must be scheduled next to the call.
 624   // Collect all the defined registers.
 625   for (DUIterator_Fast imax, i = mcall->fast_outs(imax); i < imax; i++) {
 626     Node* n = mcall->fast_out(i);
 627     assert( n->is_MachProj(), "" );
 628     int n_cnt = ready_cnt.at(n->_idx)-1;
 629     ready_cnt.at_put(n->_idx, n_cnt);
 630     assert( n_cnt == 0, "" );
 631     // Schedule next to call
 632     block->map_node(n, node_cnt++);
 633     // Collect defined registers
 634     regs.OR(n->out_RegMask());
 635     // Check for scheduling the next control-definer
 636     if( n->bottom_type() == Type::CONTROL )
 637       // Warm up next pile of heuristic bits
 638       needed_for_next_call(block, n, next_call);
 639 
 640     // Children of projections are now all ready
 641     for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
 642       Node* m = n->fast_out(j); // Get user
 643       if(get_block_for_node(m) != block) {
 644         continue;
 645       }
 646       if( m->is_Phi() ) continue;
 647       int m_cnt = ready_cnt.at(m->_idx)-1;
 648       ready_cnt.at_put(m->_idx, m_cnt);
 649       if( m_cnt == 0 )
 650         worklist.push(m);
 651     }
 652 
 653   }
 654 
 655   // Act as if the call defines the Frame Pointer.
 656   // Certainly the FP is alive and well after the call.
 657   regs.Insert(_matcher.c_frame_pointer());
 658 
 659   // Set all registers killed and not already defined by the call.
 660   uint r_cnt = mcall->tf()->range()->cnt();
 661   int op = mcall->ideal_Opcode();
 662   MachProjNode *proj = new MachProjNode( mcall, r_cnt+1, RegMask::Empty, MachProjNode::fat_proj );
 663   map_node_to_block(proj, block);
 664   block->insert_node(proj, node_cnt++);
 665 
 666   // Select the right register save policy.
 667   const char * save_policy;
 668   switch (op) {
 669     case Op_CallRuntime:
 670     case Op_CallLeaf:
 671     case Op_CallLeafNoFP:
 672       // Calling C code so use C calling convention
 673       save_policy = _matcher._c_reg_save_policy;
 674       break;
 675 
 676     case Op_CallStaticJava:
 677     case Op_CallDynamicJava:
 678       // Calling Java code so use Java calling convention
 679       save_policy = _matcher._register_save_policy;
 680       break;
 681 
 682     default:
 683       ShouldNotReachHere();
 684   }
 685 
 686   // When using CallRuntime mark SOE registers as killed by the call
 687   // so values that could show up in the RegisterMap aren't live in a
 688   // callee saved register since the register wouldn't know where to
 689   // find them.  CallLeaf and CallLeafNoFP are ok because they can't
 690   // have debug info on them.  Strictly speaking this only needs to be
 691   // done for oops since idealreg2debugmask takes care of debug info
 692   // references but there no way to handle oops differently than other
 693   // pointers as far as the kill mask goes.
 694   bool exclude_soe = op == Op_CallRuntime;
 695 
 696   // If the call is a MethodHandle invoke, we need to exclude the
 697   // register which is used to save the SP value over MH invokes from
 698   // the mask.  Otherwise this register could be used for
 699   // deoptimization information.
 700   if (op == Op_CallStaticJava) {
 701     MachCallStaticJavaNode* mcallstaticjava = (MachCallStaticJavaNode*) mcall;
 702     if (mcallstaticjava->_method_handle_invoke)
 703       proj->_rout.OR(Matcher::method_handle_invoke_SP_save_mask());
 704   }
 705 
 706   add_call_kills(proj, regs, save_policy, exclude_soe);
 707 
 708   return node_cnt;
 709 }
 710 
 711 
 712 //------------------------------schedule_local---------------------------------
 713 // Topological sort within a block.  Someday become a real scheduler.
 714 bool PhaseCFG::schedule_local(Block* block, GrowableArray<int>& ready_cnt, VectorSet& next_call) {
 715   // Already "sorted" are the block start Node (as the first entry), and
 716   // the block-ending Node and any trailing control projections.  We leave
 717   // these alone.  PhiNodes and ParmNodes are made to follow the block start
 718   // Node.  Everything else gets topo-sorted.
 719 
 720 #ifndef PRODUCT
 721     if (trace_opto_pipelining()) {
 722       tty->print_cr("# --- schedule_local B%d, before: ---", block->_pre_order);
 723       for (uint i = 0;i < block->number_of_nodes(); i++) {
 724         tty->print("# ");
 725         block->get_node(i)->fast_dump();
 726       }
 727       tty->print_cr("#");
 728     }
 729 #endif
 730 
 731   // RootNode is already sorted
 732   if (block->number_of_nodes() == 1) {
 733     return true;
 734   }
 735 
 736   // Move PhiNodes and ParmNodes from 1 to cnt up to the start
 737   uint node_cnt = block->end_idx();
 738   uint phi_cnt = 1;
 739   uint i;
 740   for( i = 1; i<node_cnt; i++ ) { // Scan for Phi
 741     Node *n = block->get_node(i);
 742     if( n->is_Phi() ||          // Found a PhiNode or ParmNode
 743         (n->is_Proj()  && n->in(0) == block->head()) ) {
 744       // Move guy at 'phi_cnt' to the end; makes a hole at phi_cnt
 745       block->map_node(block->get_node(phi_cnt), i);
 746       block->map_node(n, phi_cnt++);  // swap Phi/Parm up front
 747     } else {                    // All others
 748       // Count block-local inputs to 'n'
 749       uint cnt = n->len();      // Input count
 750       uint local = 0;
 751       for( uint j=0; j<cnt; j++ ) {
 752         Node *m = n->in(j);
 753         if( m && get_block_for_node(m) == block && !m->is_top() )
 754           local++;              // One more block-local input
 755       }
 756       ready_cnt.at_put(n->_idx, local); // Count em up
 757 
 758 #ifdef ASSERT
 759       if( UseConcMarkSweepGC || UseG1GC ) {
 760         if( n->is_Mach() && n->as_Mach()->ideal_Opcode() == Op_StoreCM ) {
 761           // Check the precedence edges
 762           for (uint prec = n->req(); prec < n->len(); prec++) {
 763             Node* oop_store = n->in(prec);
 764             if (oop_store != NULL) {
 765               assert(get_block_for_node(oop_store)->_dom_depth <= block->_dom_depth, "oop_store must dominate card-mark");
 766             }
 767           }
 768         }
 769       }
 770 #endif
 771 
 772       // A few node types require changing a required edge to a precedence edge
 773       // before allocation.
 774       if( n->is_Mach() && n->req() > TypeFunc::Parms &&
 775           (n->as_Mach()->ideal_Opcode() == Op_MemBarAcquire ||
 776            n->as_Mach()->ideal_Opcode() == Op_MemBarVolatile) ) {
 777         // MemBarAcquire could be created without Precedent edge.
 778         // del_req() replaces the specified edge with the last input edge
 779         // and then removes the last edge. If the specified edge > number of
 780         // edges the last edge will be moved outside of the input edges array
 781         // and the edge will be lost. This is why this code should be
 782         // executed only when Precedent (== TypeFunc::Parms) edge is present.
 783         Node *x = n->in(TypeFunc::Parms);
 784         n->del_req(TypeFunc::Parms);
 785         n->add_prec(x);
 786       }
 787     }
 788   }
 789   for(uint i2=i; i2< block->number_of_nodes(); i2++ ) // Trailing guys get zapped count
 790     ready_cnt.at_put(block->get_node(i2)->_idx, 0);
 791 
 792   // All the prescheduled guys do not hold back internal nodes
 793   uint i3;
 794   for(i3 = 0; i3<phi_cnt; i3++ ) {  // For all pre-scheduled
 795     Node *n = block->get_node(i3);       // Get pre-scheduled
 796     for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
 797       Node* m = n->fast_out(j);
 798       if (get_block_for_node(m) == block) { // Local-block user
 799         int m_cnt = ready_cnt.at(m->_idx)-1;
 800         ready_cnt.at_put(m->_idx, m_cnt);   // Fix ready count
 801       }
 802     }
 803   }
 804 
 805   Node_List delay;
 806   // Make a worklist
 807   Node_List worklist;
 808   for(uint i4=i3; i4<node_cnt; i4++ ) {    // Put ready guys on worklist
 809     Node *m = block->get_node(i4);
 810     if( !ready_cnt.at(m->_idx) ) {   // Zero ready count?
 811       if (m->is_iteratively_computed()) {
 812         // Push induction variable increments last to allow other uses
 813         // of the phi to be scheduled first. The select() method breaks
 814         // ties in scheduling by worklist order.
 815         delay.push(m);
 816       } else if (m->is_Mach() && m->as_Mach()->ideal_Opcode() == Op_CreateEx) {
 817         // Force the CreateEx to the top of the list so it's processed
 818         // first and ends up at the start of the block.
 819         worklist.insert(0, m);
 820       } else {
 821         worklist.push(m);         // Then on to worklist!
 822       }
 823     }
 824   }
 825   while (delay.size()) {
 826     Node* d = delay.pop();
 827     worklist.push(d);
 828   }
 829 
 830   // Warm up the 'next_call' heuristic bits
 831   needed_for_next_call(block, block->head(), next_call);
 832 
 833 #ifndef PRODUCT
 834     if (trace_opto_pipelining()) {
 835       for (uint j=0; j< block->number_of_nodes(); j++) {
 836         Node     *n = block->get_node(j);
 837         int     idx = n->_idx;
 838         tty->print("#   ready cnt:%3d  ", ready_cnt.at(idx));
 839         tty->print("latency:%3d  ", get_latency_for_node(n));
 840         tty->print("%4d: %s\n", idx, n->Name());
 841       }
 842     }
 843 #endif
 844 
 845   uint max_idx = (uint)ready_cnt.length();
 846   // Pull from worklist and schedule
 847   while( worklist.size() ) {    // Worklist is not ready
 848 
 849 #ifndef PRODUCT
 850     if (trace_opto_pipelining()) {
 851       tty->print("#   ready list:");
 852       for( uint i=0; i<worklist.size(); i++ ) { // Inspect entire worklist
 853         Node *n = worklist[i];      // Get Node on worklist
 854         tty->print(" %d", n->_idx);
 855       }
 856       tty->cr();
 857     }
 858 #endif
 859 
 860     // Select and pop a ready guy from worklist
 861     Node* n = select(block, worklist, ready_cnt, next_call, phi_cnt);
 862     block->map_node(n, phi_cnt++);    // Schedule him next
 863 
 864 #ifndef PRODUCT
 865     if (trace_opto_pipelining()) {
 866       tty->print("#    select %d: %s", n->_idx, n->Name());
 867       tty->print(", latency:%d", get_latency_for_node(n));
 868       n->dump();
 869       if (Verbose) {
 870         tty->print("#   ready list:");
 871         for( uint i=0; i<worklist.size(); i++ ) { // Inspect entire worklist
 872           Node *n = worklist[i];      // Get Node on worklist
 873           tty->print(" %d", n->_idx);
 874         }
 875         tty->cr();
 876       }
 877     }
 878 
 879 #endif
 880     if( n->is_MachCall() ) {
 881       MachCallNode *mcall = n->as_MachCall();
 882       phi_cnt = sched_call(block, phi_cnt, worklist, ready_cnt, mcall, next_call);
 883       continue;
 884     }
 885 
 886     if (n->is_Mach() && n->as_Mach()->has_call()) {
 887       RegMask regs;
 888       regs.Insert(_matcher.c_frame_pointer());
 889       regs.OR(n->out_RegMask());
 890 
 891       MachProjNode *proj = new MachProjNode( n, 1, RegMask::Empty, MachProjNode::fat_proj );
 892       map_node_to_block(proj, block);
 893       block->insert_node(proj, phi_cnt++);
 894 
 895       add_call_kills(proj, regs, _matcher._c_reg_save_policy, false);
 896     }
 897 
 898     // Children are now all ready
 899     for (DUIterator_Fast i5max, i5 = n->fast_outs(i5max); i5 < i5max; i5++) {
 900       Node* m = n->fast_out(i5); // Get user
 901       if (get_block_for_node(m) != block) {
 902         continue;
 903       }
 904       if( m->is_Phi() ) continue;
 905       if (m->_idx >= max_idx) { // new node, skip it
 906         assert(m->is_MachProj() && n->is_Mach() && n->as_Mach()->has_call(), "unexpected node types");
 907         continue;
 908       }
 909       int m_cnt = ready_cnt.at(m->_idx)-1;
 910       ready_cnt.at_put(m->_idx, m_cnt);
 911       if( m_cnt == 0 )
 912         worklist.push(m);
 913     }
 914   }
 915 
 916   if( phi_cnt != block->end_idx() ) {
 917     // did not schedule all.  Retry, Bailout, or Die
 918     if (C->subsume_loads() == true && !C->failing()) {
 919       // Retry with subsume_loads == false
 920       // If this is the first failure, the sentinel string will "stick"
 921       // to the Compile object, and the C2Compiler will see it and retry.
 922       C->record_failure(C2Compiler::retry_no_subsuming_loads());
 923     }
 924     // assert( phi_cnt == end_idx(), "did not schedule all" );
 925     return false;
 926   }
 927 
 928 #ifndef PRODUCT
 929   if (trace_opto_pipelining()) {
 930     tty->print_cr("#");
 931     tty->print_cr("# after schedule_local");
 932     for (uint i = 0;i < block->number_of_nodes();i++) {
 933       tty->print("# ");
 934       block->get_node(i)->fast_dump();
 935     }
 936     tty->cr();
 937   }
 938 #endif
 939 
 940 
 941   return true;
 942 }
 943 
 944 //--------------------------catch_cleanup_fix_all_inputs-----------------------
 945 static void catch_cleanup_fix_all_inputs(Node *use, Node *old_def, Node *new_def) {
 946   for (uint l = 0; l < use->len(); l++) {
 947     if (use->in(l) == old_def) {
 948       if (l < use->req()) {
 949         use->set_req(l, new_def);
 950       } else {
 951         use->rm_prec(l);
 952         use->add_prec(new_def);
 953         l--;
 954       }
 955     }
 956   }
 957 }
 958 
 959 //------------------------------catch_cleanup_find_cloned_def------------------
 960 Node* PhaseCFG::catch_cleanup_find_cloned_def(Block *use_blk, Node *def, Block *def_blk, int n_clone_idx) {
 961   assert( use_blk != def_blk, "Inter-block cleanup only");
 962 
 963   // The use is some block below the Catch.  Find and return the clone of the def
 964   // that dominates the use. If there is no clone in a dominating block, then
 965   // create a phi for the def in a dominating block.
 966 
 967   // Find which successor block dominates this use.  The successor
 968   // blocks must all be single-entry (from the Catch only; I will have
 969   // split blocks to make this so), hence they all dominate.
 970   while( use_blk->_dom_depth > def_blk->_dom_depth+1 )
 971     use_blk = use_blk->_idom;
 972 
 973   // Find the successor
 974   Node *fixup = NULL;
 975 
 976   uint j;
 977   for( j = 0; j < def_blk->_num_succs; j++ )
 978     if( use_blk == def_blk->_succs[j] )
 979       break;
 980 
 981   if( j == def_blk->_num_succs ) {
 982     // Block at same level in dom-tree is not a successor.  It needs a
 983     // PhiNode, the PhiNode uses from the def and IT's uses need fixup.
 984     Node_Array inputs = new Node_List(Thread::current()->resource_area());
 985     for(uint k = 1; k < use_blk->num_preds(); k++) {
 986       Block* block = get_block_for_node(use_blk->pred(k));
 987       inputs.map(k, catch_cleanup_find_cloned_def(block, def, def_blk, n_clone_idx));
 988     }
 989 
 990     // Check to see if the use_blk already has an identical phi inserted.
 991     // If it exists, it will be at the first position since all uses of a
 992     // def are processed together.
 993     Node *phi = use_blk->get_node(1);
 994     if( phi->is_Phi() ) {
 995       fixup = phi;
 996       for (uint k = 1; k < use_blk->num_preds(); k++) {
 997         if (phi->in(k) != inputs[k]) {
 998           // Not a match
 999           fixup = NULL;
1000           break;
1001         }
1002       }
1003     }
1004 
1005     // If an existing PhiNode was not found, make a new one.
1006     if (fixup == NULL) {
1007       Node *new_phi = PhiNode::make(use_blk->head(), def);
1008       use_blk->insert_node(new_phi, 1);
1009       map_node_to_block(new_phi, use_blk);
1010       for (uint k = 1; k < use_blk->num_preds(); k++) {
1011         new_phi->set_req(k, inputs[k]);
1012       }
1013       fixup = new_phi;
1014     }
1015 
1016   } else {
1017     // Found the use just below the Catch.  Make it use the clone.
1018     fixup = use_blk->get_node(n_clone_idx);
1019   }
1020 
1021   return fixup;
1022 }
1023 
1024 //--------------------------catch_cleanup_intra_block--------------------------
1025 // Fix all input edges in use that reference "def".  The use is in the same
1026 // block as the def and both have been cloned in each successor block.
1027 static void catch_cleanup_intra_block(Node *use, Node *def, Block *blk, int beg, int n_clone_idx) {
1028 
1029   // Both the use and def have been cloned. For each successor block,
1030   // get the clone of the use, and make its input the clone of the def
1031   // found in that block.
1032 
1033   uint use_idx = blk->find_node(use);
1034   uint offset_idx = use_idx - beg;
1035   for( uint k = 0; k < blk->_num_succs; k++ ) {
1036     // Get clone in each successor block
1037     Block *sb = blk->_succs[k];
1038     Node *clone = sb->get_node(offset_idx+1);
1039     assert( clone->Opcode() == use->Opcode(), "" );
1040 
1041     // Make use-clone reference the def-clone
1042     catch_cleanup_fix_all_inputs(clone, def, sb->get_node(n_clone_idx));
1043   }
1044 }
1045 
1046 //------------------------------catch_cleanup_inter_block---------------------
1047 // Fix all input edges in use that reference "def".  The use is in a different
1048 // block than the def.
1049 void PhaseCFG::catch_cleanup_inter_block(Node *use, Block *use_blk, Node *def, Block *def_blk, int n_clone_idx) {
1050   if( !use_blk ) return;        // Can happen if the use is a precedence edge
1051 
1052   Node *new_def = catch_cleanup_find_cloned_def(use_blk, def, def_blk, n_clone_idx);
1053   catch_cleanup_fix_all_inputs(use, def, new_def);
1054 }
1055 
1056 //------------------------------call_catch_cleanup-----------------------------
1057 // If we inserted any instructions between a Call and his CatchNode,
1058 // clone the instructions on all paths below the Catch.
1059 void PhaseCFG::call_catch_cleanup(Block* block) {
1060 
1061   // End of region to clone
1062   uint end = block->end_idx();
1063   if( !block->get_node(end)->is_Catch() ) return;
1064   // Start of region to clone
1065   uint beg = end;
1066   while(!block->get_node(beg-1)->is_MachProj() ||
1067         !block->get_node(beg-1)->in(0)->is_MachCall() ) {
1068     beg--;
1069     assert(beg > 0,"Catch cleanup walking beyond block boundary");
1070   }
1071   // Range of inserted instructions is [beg, end)
1072   if( beg == end ) return;
1073 
1074   // Clone along all Catch output paths.  Clone area between the 'beg' and
1075   // 'end' indices.
1076   for( uint i = 0; i < block->_num_succs; i++ ) {
1077     Block *sb = block->_succs[i];
1078     // Clone the entire area; ignoring the edge fixup for now.
1079     for( uint j = end; j > beg; j-- ) {
1080       // It is safe here to clone a node with anti_dependence
1081       // since clones dominate on each path.
1082       Node *clone = block->get_node(j-1)->clone();
1083       sb->insert_node(clone, 1);
1084       map_node_to_block(clone, sb);
1085     }
1086   }
1087 
1088 
1089   // Fixup edges.  Check the def-use info per cloned Node
1090   for(uint i2 = beg; i2 < end; i2++ ) {
1091     uint n_clone_idx = i2-beg+1; // Index of clone of n in each successor block
1092     Node *n = block->get_node(i2);        // Node that got cloned
1093     // Need DU safe iterator because of edge manipulation in calls.
1094     Unique_Node_List *out = new Unique_Node_List(Thread::current()->resource_area());
1095     for (DUIterator_Fast j1max, j1 = n->fast_outs(j1max); j1 < j1max; j1++) {
1096       out->push(n->fast_out(j1));
1097     }
1098     uint max = out->size();
1099     for (uint j = 0; j < max; j++) {// For all users
1100       Node *use = out->pop();
1101       Block *buse = get_block_for_node(use);
1102       if( use->is_Phi() ) {
1103         for( uint k = 1; k < use->req(); k++ )
1104           if( use->in(k) == n ) {
1105             Block* b = get_block_for_node(buse->pred(k));
1106             Node *fixup = catch_cleanup_find_cloned_def(b, n, block, n_clone_idx);
1107             use->set_req(k, fixup);
1108           }
1109       } else {
1110         if (block == buse) {
1111           catch_cleanup_intra_block(use, n, block, beg, n_clone_idx);
1112         } else {
1113           catch_cleanup_inter_block(use, buse, n, block, n_clone_idx);
1114         }
1115       }
1116     } // End for all users
1117 
1118   } // End of for all Nodes in cloned area
1119 
1120   // Remove the now-dead cloned ops
1121   for(uint i3 = beg; i3 < end; i3++ ) {
1122     block->get_node(beg)->disconnect_inputs(NULL, C);
1123     block->remove_node(beg);
1124   }
1125 
1126   // If the successor blocks have a CreateEx node, move it back to the top
1127   for(uint i4 = 0; i4 < block->_num_succs; i4++ ) {
1128     Block *sb = block->_succs[i4];
1129     uint new_cnt = end - beg;
1130     // Remove any newly created, but dead, nodes.
1131     for( uint j = new_cnt; j > 0; j-- ) {
1132       Node *n = sb->get_node(j);
1133       if (n->outcnt() == 0 &&
1134           (!n->is_Proj() || n->as_Proj()->in(0)->outcnt() == 1) ){
1135         n->disconnect_inputs(NULL, C);
1136         sb->remove_node(j);
1137         new_cnt--;
1138       }
1139     }
1140     // If any newly created nodes remain, move the CreateEx node to the top
1141     if (new_cnt > 0) {
1142       Node *cex = sb->get_node(1+new_cnt);
1143       if( cex->is_Mach() && cex->as_Mach()->ideal_Opcode() == Op_CreateEx ) {
1144         sb->remove_node(1+new_cnt);
1145         sb->insert_node(cex, 1);
1146       }
1147     }
1148   }
1149 }