rev 50711 : ZGC: C2: Remove dead code

   1 /*
   2  * Copyright (c) 2015, 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 #include "precompiled.hpp"
  25 #include "opto/compile.hpp"
  26 #include "opto/castnode.hpp"
  27 #include "opto/graphKit.hpp"
  28 #include "opto/idealKit.hpp"
  29 #include "opto/loopnode.hpp"
  30 #include "opto/macro.hpp"
  31 #include "opto/node.hpp"
  32 #include "opto/type.hpp"
  33 #include "utilities/macros.hpp"
  34 #include "gc/z/c2/zBarrierSetC2.hpp"
  35 #include "gc/z/zThreadLocalData.hpp"
  36 #include "gc/z/zBarrierSetRuntime.hpp"
  37 
  38 ZBarrierSetC2State::ZBarrierSetC2State(Arena* comp_arena)
  39   : _load_barrier_nodes(new (comp_arena) GrowableArray<LoadBarrierNode*>(comp_arena, 8,  0, NULL)) {}
  40 
  41 int ZBarrierSetC2State::load_barrier_count() const {
  42   return _load_barrier_nodes->length();
  43 }
  44 
  45 void ZBarrierSetC2State::add_load_barrier_node(LoadBarrierNode * n) {
  46   assert(!_load_barrier_nodes->contains(n), " duplicate entry in expand list");
  47   _load_barrier_nodes->append(n);
  48 }
  49 
  50 void ZBarrierSetC2State::remove_load_barrier_node(LoadBarrierNode * n) {
  51   // this function may be called twice for a node so check
  52   // that the node is in the array before attempting to remove it
  53   if (_load_barrier_nodes->contains(n)) {
  54     _load_barrier_nodes->remove(n);
  55   }
  56 }
  57 
  58 LoadBarrierNode* ZBarrierSetC2State::load_barrier_node(int idx) const {
  59   return _load_barrier_nodes->at(idx);
  60 }
  61 
  62 void* ZBarrierSetC2::create_barrier_state(Arena* comp_arena) const {
  63   return new(comp_arena) ZBarrierSetC2State(comp_arena);
  64 }
  65 
  66 ZBarrierSetC2State* ZBarrierSetC2::state() const {
  67   return reinterpret_cast<ZBarrierSetC2State*>(Compile::current()->barrier_set_state());
  68 }
  69 
  70 bool ZBarrierSetC2::is_gc_barrier_node(Node* node) const {
  71   return node->is_LoadBarrier();
  72 }
  73 
  74 void ZBarrierSetC2::register_potential_barrier_node(Node* node) const {
  75   if (node->is_LoadBarrier()) {
  76     state()->add_load_barrier_node(node->as_LoadBarrier());
  77   }
  78 }
  79 
  80 void ZBarrierSetC2::unregister_potential_barrier_node(Node* node) const {
  81   if (node->is_LoadBarrier()) {
  82     state()->remove_load_barrier_node(node->as_LoadBarrier());
  83   }
  84 }
  85 
  86 void ZBarrierSetC2::eliminate_useless_gc_barriers(Unique_Node_List &useful) const {
  87   // Remove useless LoadBarrier nodes
  88   ZBarrierSetC2State* s = state();
  89   for (int i = s->load_barrier_count()-1; i >= 0; i--) {
  90     LoadBarrierNode* n = s->load_barrier_node(i);
  91     if (!useful.member(n)) {
  92       unregister_potential_barrier_node(n);
  93     }
  94   }
  95 }
  96 
  97 void ZBarrierSetC2::enqueue_useful_gc_barrier(Unique_Node_List &worklist, Node* node) const {
  98   if (node->is_LoadBarrier() && !node->as_LoadBarrier()->has_true_uses()) {
  99     worklist.push(node);
 100   }
 101 }
 102 
 103 void ZBarrierSetC2::find_dominating_barriers(PhaseIterGVN& igvn) {
 104   // Look for dominating barriers on the same address only once all
 105   // other loop opts are over: loop opts may cause a safepoint to be
 106   // inserted between a barrier and its dominating barrier.
 107   Compile* C = Compile::current();
 108   ZBarrierSetC2* bs = (ZBarrierSetC2*)BarrierSet::barrier_set()->barrier_set_c2();
 109   ZBarrierSetC2State* s = bs->state();
 110   if (s->load_barrier_count() >= 2) {
 111     Compile::TracePhase tp("idealLoop", &C->timers[Phase::_t_idealLoop]);
 112     PhaseIdealLoop ideal_loop(igvn, true, false, true);
 113     if (C->major_progress()) C->print_method(PHASE_PHASEIDEALLOOP_ITERATIONS, 2);
 114   }
 115 }
 116 
 117 void ZBarrierSetC2::add_users_to_worklist(Unique_Node_List* worklist) const {
 118   // Permanent temporary workaround
 119   // Loadbarriers may have non-obvious dead uses keeping them alive during parsing. The use is
 120   // removed by RemoveUseless (after parsing, before optimize) but the barriers won't be added to
 121   // the worklist. Unless we add them explicitly they are not guaranteed to end up there.
 122   ZBarrierSetC2State* s = state();
 123 
 124   for (int i = 0; i < s->load_barrier_count(); i++) {
 125     LoadBarrierNode* n = s->load_barrier_node(i);
 126     worklist->push(n);
 127   }
 128 }
 129 
 130 const TypeFunc* ZBarrierSetC2::load_barrier_Type() const {
 131   const Type** fields;
 132 
 133   // Create input types (domain)
 134   fields = TypeTuple::fields(2);
 135   fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL;
 136   fields[TypeFunc::Parms+1] = TypeOopPtr::BOTTOM;
 137   const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+2, fields);
 138 
 139   // Create result type (range)
 140   fields = TypeTuple::fields(1);
 141   fields[TypeFunc::Parms+0] = TypeInstPtr::BOTTOM;
 142   const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+1, fields);
 143 
 144   return TypeFunc::make(domain, range);
 145 }
 146 
 147 // == LoadBarrierNode ==
 148 
 149 LoadBarrierNode::LoadBarrierNode(Compile* C,
 150                                  Node* c,
 151                                  Node* mem,
 152                                  Node* val,
 153                                  Node* adr,
 154                                  bool weak,
 155                                  bool writeback,
 156                                  bool oop_reload_allowed) :
 157     MultiNode(Number_of_Inputs),
 158     _weak(weak),
 159     _writeback(writeback),
 160     _oop_reload_allowed(oop_reload_allowed) {
 161   init_req(Control, c);
 162   init_req(Memory, mem);
 163   init_req(Oop, val);
 164   init_req(Address, adr);
 165   init_req(Similar, C->top());
 166 
 167   init_class_id(Class_LoadBarrier);
 168   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
 169   bs->register_potential_barrier_node(this);
 170 }
 171 
 172 const Type *LoadBarrierNode::bottom_type() const {
 173   const Type** floadbarrier = (const Type **)(Compile::current()->type_arena()->Amalloc_4((Number_of_Outputs)*sizeof(Type*)));
 174   Node* in_oop = in(Oop);
 175   floadbarrier[Control] = Type::CONTROL;
 176   floadbarrier[Memory] = Type::MEMORY;
 177   floadbarrier[Oop] = in_oop == NULL ? Type::TOP : in_oop->bottom_type();
 178   return TypeTuple::make(Number_of_Outputs, floadbarrier);
 179 }
 180 
 181 const Type *LoadBarrierNode::Value(PhaseGVN *phase) const {
 182   const Type** floadbarrier = (const Type **)(phase->C->type_arena()->Amalloc_4((Number_of_Outputs)*sizeof(Type*)));
 183   const Type* val_t = phase->type(in(Oop));
 184   floadbarrier[Control] = Type::CONTROL;
 185   floadbarrier[Memory] = Type::MEMORY;
 186   floadbarrier[Oop] = val_t;
 187   return TypeTuple::make(Number_of_Outputs, floadbarrier);
 188 }
 189 
 190 bool LoadBarrierNode::is_dominator(PhaseIdealLoop* phase, bool linear_only, Node *d, Node *n) {
 191   if (phase != NULL) {
 192     return phase->is_dominator(d, n);
 193   }
 194 
 195   for (int i = 0; i < 10 && n != NULL; i++) {
 196     n = IfNode::up_one_dom(n, linear_only);
 197     if (n == d) {
 198       return true;
 199     }
 200   }
 201 
 202   return false;
 203 }
 204 
 205 LoadBarrierNode* LoadBarrierNode::has_dominating_barrier(PhaseIdealLoop* phase, bool linear_only, bool look_for_similar) {
 206   Node* val = in(LoadBarrierNode::Oop);
 207   if (in(Similar)->is_Proj() && in(Similar)->in(0)->is_LoadBarrier()) {
 208     LoadBarrierNode* lb = in(Similar)->in(0)->as_LoadBarrier();
 209     assert(lb->in(Address) == in(Address), "");
 210     // Load barrier on Similar edge dominates so if it now has the Oop field it can replace this barrier.
 211     if (lb->in(Oop) == in(Oop)) {
 212       return lb;
 213     }
 214     // Follow chain of load barrier through Similar edges
 215     while (!lb->in(Similar)->is_top()) {
 216       lb = lb->in(Similar)->in(0)->as_LoadBarrier();
 217       assert(lb->in(Address) == in(Address), "");
 218     }
 219     if (lb != in(Similar)->in(0)) {
 220       return lb;
 221     }
 222   }
 223   for (DUIterator_Fast imax, i = val->fast_outs(imax); i < imax; i++) {
 224     Node* u = val->fast_out(i);
 225     if (u != this && u->is_LoadBarrier() && u->in(Oop) == val && u->as_LoadBarrier()->has_true_uses()) {
 226       Node* this_ctrl = in(LoadBarrierNode::Control);
 227       Node* other_ctrl = u->in(LoadBarrierNode::Control);
 228       if (is_dominator(phase, linear_only, other_ctrl, this_ctrl)) {
 229         return u->as_LoadBarrier();
 230       }
 231     }
 232   }
 233 
 234   if (ZVerifyLoadBarriers || can_be_eliminated()) {
 235     return NULL;
 236   }
 237 
 238   if (!look_for_similar) {
 239     return NULL;
 240   }
 241 
 242   Node* addr = in(LoadBarrierNode::Address);
 243   for (DUIterator_Fast imax, i = addr->fast_outs(imax); i < imax; i++) {
 244     Node* u = addr->fast_out(i);
 245     if (u != this && u->is_LoadBarrier() && u->as_LoadBarrier()->has_true_uses()) {
 246       Node* this_ctrl = in(LoadBarrierNode::Control);
 247       Node* other_ctrl = u->in(LoadBarrierNode::Control);
 248       if (is_dominator(phase, linear_only, other_ctrl, this_ctrl)) {
 249         ResourceMark rm;
 250         Unique_Node_List wq;
 251         wq.push(in(LoadBarrierNode::Control));
 252         bool ok = true;
 253         bool dom_found = false;
 254         for (uint next = 0; next < wq.size(); ++next) {
 255           Node *n = wq.at(next);
 256           if (n->is_top()) {
 257             return NULL;
 258           }
 259           assert(n->is_CFG(), "");
 260           if (n->is_SafePoint()) {
 261             ok = false;
 262             break;
 263           }
 264           if (n == u) {
 265             dom_found = true;
 266             continue;
 267           }
 268           if (n->is_Region()) {
 269             for (uint i = 1; i < n->req(); i++) {
 270               Node* m = n->in(i);
 271               if (m != NULL) {
 272                 wq.push(m);
 273               }
 274             }
 275           } else {
 276             Node* m = n->in(0);
 277             if (m != NULL) {
 278               wq.push(m);
 279             }
 280           }
 281         }
 282         if (ok) {
 283           assert(dom_found, "");
 284           return u->as_LoadBarrier();;
 285         }
 286         break;
 287       }
 288     }
 289   }
 290 
 291   return NULL;
 292 }
 293 
 294 void LoadBarrierNode::push_dominated_barriers(PhaseIterGVN* igvn) const {
 295   // change to that barrier may affect a dominated barrier so re-push those
 296   Node* val = in(LoadBarrierNode::Oop);
 297 
 298   for (DUIterator_Fast imax, i = val->fast_outs(imax); i < imax; i++) {
 299     Node* u = val->fast_out(i);
 300     if (u != this && u->is_LoadBarrier() && u->in(Oop) == val) {
 301       Node* this_ctrl = in(Control);
 302       Node* other_ctrl = u->in(Control);
 303       if (is_dominator(NULL, false, this_ctrl, other_ctrl)) {
 304         igvn->_worklist.push(u);
 305       }
 306     }
 307 
 308     Node* addr = in(LoadBarrierNode::Address);
 309     for (DUIterator_Fast imax, i = addr->fast_outs(imax); i < imax; i++) {
 310       Node* u = addr->fast_out(i);
 311       if (u != this && u->is_LoadBarrier() && u->in(Similar)->is_top()) {
 312         Node* this_ctrl = in(Control);
 313         Node* other_ctrl = u->in(Control);
 314         if (is_dominator(NULL, false, this_ctrl, other_ctrl)) {
 315           igvn->_worklist.push(u);
 316         }
 317       }
 318     }
 319   }
 320 }
 321 
 322 Node *LoadBarrierNode::Identity(PhaseGVN *phase) {
 323   if (!phase->C->directive()->ZOptimizeLoadBarriersOption) {
 324     return this;
 325   }
 326 
 327   bool redundant_addr = false;
 328   LoadBarrierNode* dominating_barrier = has_dominating_barrier(NULL, true, false);
 329   if (dominating_barrier != NULL) {
 330     assert(dominating_barrier->in(Oop) == in(Oop), "");
 331     return dominating_barrier;
 332   }
 333 
 334   return this;
 335 }
 336 
 337 Node *LoadBarrierNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 338   if (remove_dead_region(phase, can_reshape)) {
 339     return this;
 340   }
 341 
 342   Node* val = in(Oop);
 343   Node* mem = in(Memory);
 344   Node* ctrl = in(Control);
 345   Node* adr = in(Address);
 346   assert(val->Opcode() != Op_LoadN, "");
 347 
 348   if (mem->is_MergeMem()) {
 349     Node* new_mem = mem->as_MergeMem()->memory_at(Compile::AliasIdxRaw);
 350     set_req(Memory, new_mem);
 351     if (mem->outcnt() == 0 && can_reshape) {
 352       phase->is_IterGVN()->_worklist.push(mem);
 353     }
 354 
 355     return this;
 356   }
 357 
 358   bool optimizeLoadBarriers = phase->C->directive()->ZOptimizeLoadBarriersOption;
 359   LoadBarrierNode* dominating_barrier = optimizeLoadBarriers ? has_dominating_barrier(NULL, !can_reshape, !phase->C->major_progress()) : NULL;
 360   if (dominating_barrier != NULL && dominating_barrier->in(Oop) != in(Oop)) {
 361     assert(in(Address) == dominating_barrier->in(Address), "");
 362     set_req(Similar, dominating_barrier->proj_out(Oop));
 363     return this;
 364   }
 365 
 366   bool eliminate = (optimizeLoadBarriers && !(val->is_Phi() || val->Opcode() == Op_LoadP || val->Opcode() == Op_GetAndSetP || val->is_DecodeN())) ||
 367                    (can_reshape && (dominating_barrier != NULL || !has_true_uses()));
 368 
 369   if (eliminate) {
 370     if (can_reshape) {
 371       PhaseIterGVN* igvn = phase->is_IterGVN();
 372       Node* out_ctrl = proj_out_or_null(Control);
 373       Node* out_res = proj_out_or_null(Oop);
 374 
 375       if (out_ctrl != NULL) {
 376         igvn->replace_node(out_ctrl, ctrl);
 377       }
 378 
 379       // That transformation may cause the Similar edge on the load barrier to be invalid
 380       fix_similar_in_uses(igvn);
 381       if (out_res != NULL) {
 382         if (dominating_barrier != NULL) {
 383           igvn->replace_node(out_res, dominating_barrier->proj_out(Oop));
 384         } else {
 385           igvn->replace_node(out_res, val);
 386         }
 387       }
 388     }
 389 
 390     return new ConINode(TypeInt::ZERO);
 391   }
 392 
 393   // If the Similar edge is no longer a load barrier, clear it
 394   Node* similar = in(Similar);
 395   if (!similar->is_top() && !(similar->is_Proj() && similar->in(0)->is_LoadBarrier())) {
 396     set_req(Similar, phase->C->top());
 397     return this;
 398   }
 399 
 400   if (can_reshape) {
 401     // If this barrier is linked through the Similar edge by a
 402     // dominated barrier and both barriers have the same Oop field,
 403     // the dominated barrier can go away, so push it for reprocessing.
 404     // We also want to avoid a barrier to depend on another dominating
 405     // barrier through its Similar edge that itself depend on another
 406     // barrier through its Similar edge and rather have the first
 407     // depend on the third.
 408     PhaseIterGVN* igvn = phase->is_IterGVN();
 409     Node* out_res = proj_out(Oop);
 410     for (DUIterator_Fast imax, i = out_res->fast_outs(imax); i < imax; i++) {
 411       Node* u = out_res->fast_out(i);
 412       if (u->is_LoadBarrier() && u->in(Similar) == out_res &&
 413           (u->in(Oop) == val || !u->in(Similar)->is_top())) {
 414         igvn->_worklist.push(u);
 415       }
 416     }
 417 
 418     push_dominated_barriers(igvn);
 419   }
 420 
 421   return NULL;
 422 }
 423 
 424 void LoadBarrierNode::fix_similar_in_uses(PhaseIterGVN* igvn) {
 425   Node* out_res = proj_out_or_null(Oop);
 426   if (out_res == NULL) {
 427     return;
 428   }
 429 
 430   for (DUIterator_Fast imax, i = out_res->fast_outs(imax); i < imax; i++) {
 431     Node* u = out_res->fast_out(i);
 432     if (u->is_LoadBarrier() && u->in(Similar) == out_res) {
 433       igvn->replace_input_of(u, Similar, igvn->C->top());
 434       --i;
 435       --imax;
 436     }
 437   }
 438 }
 439 
 440 bool LoadBarrierNode::has_true_uses() const {
 441   Node* out_res = proj_out_or_null(Oop);
 442   if (out_res == NULL) {
 443     return false;
 444   }
 445 
 446   for (DUIterator_Fast imax, i = out_res->fast_outs(imax); i < imax; i++) {
 447     Node* u = out_res->fast_out(i);
 448     if (!u->is_LoadBarrier() || u->in(Similar) != out_res) {
 449       return true;
 450     }
 451   }
 452 
 453   return false;
 454 }
 455 
 456 // == Accesses ==
 457 
 458 Node* ZBarrierSetC2::make_cas_loadbarrier(C2AtomicAccess& access) const {
 459   assert(!UseCompressedOops, "Not allowed");
 460   CompareAndSwapNode* cas = (CompareAndSwapNode*)access.raw_access();
 461   PhaseGVN& gvn = access.kit()->gvn();
 462   Compile* C = Compile::current();
 463   GraphKit* kit = access.kit();
 464 
 465   Node* in_ctrl     = cas->in(MemNode::Control);
 466   Node* in_mem      = cas->in(MemNode::Memory);
 467   Node* in_adr      = cas->in(MemNode::Address);
 468   Node* in_val      = cas->in(MemNode::ValueIn);
 469   Node* in_expected = cas->in(LoadStoreConditionalNode::ExpectedIn);
 470 
 471   float likely                   = PROB_LIKELY(0.999);
 472 
 473   const TypePtr *adr_type        = gvn.type(in_adr)->isa_ptr();
 474   Compile::AliasType* alias_type = C->alias_type(adr_type);
 475   int alias_idx                  = C->get_alias_index(adr_type);
 476 
 477   // Outer check - true: continue, false: load and check
 478   Node* region   = new RegionNode(3);
 479   Node* phi      = new PhiNode(region, TypeInt::BOOL);
 480   Node* phi_mem  = new PhiNode(region, Type::MEMORY, adr_type);
 481 
 482   // Inner check - is the healed ref equal to the expected
 483   Node* region2  = new RegionNode(3);
 484   Node* phi2     = new PhiNode(region2, TypeInt::BOOL);
 485   Node* phi_mem2 = new PhiNode(region2, Type::MEMORY, adr_type);
 486 
 487   // CAS node returns 0 or 1
 488   Node* cmp     = gvn.transform(new CmpINode(cas, kit->intcon(0)));
 489   Node* bol     = gvn.transform(new BoolNode(cmp, BoolTest::ne))->as_Bool();
 490   IfNode* iff   = gvn.transform(new IfNode(in_ctrl, bol, likely, COUNT_UNKNOWN))->as_If();
 491   Node* then    = gvn.transform(new IfTrueNode(iff));
 492   Node* elsen   = gvn.transform(new IfFalseNode(iff));
 493 
 494   Node* scmemproj1   = gvn.transform(new SCMemProjNode(cas));
 495 
 496   kit->set_memory(scmemproj1, alias_idx);
 497   phi_mem->init_req(1, scmemproj1);
 498   phi_mem2->init_req(2, scmemproj1);
 499 
 500   // CAS fail - reload and heal oop
 501   Node* reload      = kit->make_load(elsen, in_adr, TypeOopPtr::BOTTOM, T_OBJECT, MemNode::unordered);
 502   Node* barrier     = gvn.transform(new LoadBarrierNode(C, elsen, scmemproj1, reload, in_adr, false, true, false));
 503   Node* barrierctrl = gvn.transform(new ProjNode(barrier, LoadBarrierNode::Control));
 504   Node* barrierdata = gvn.transform(new ProjNode(barrier, LoadBarrierNode::Oop));
 505 
 506   // Check load
 507   Node* tmpX    = gvn.transform(new CastP2XNode(NULL, barrierdata));
 508   Node* in_expX = gvn.transform(new CastP2XNode(NULL, in_expected));
 509   Node* cmp2    = gvn.transform(new CmpXNode(tmpX, in_expX));
 510   Node *bol2    = gvn.transform(new BoolNode(cmp2, BoolTest::ne))->as_Bool();
 511   IfNode* iff2  = gvn.transform(new IfNode(barrierctrl, bol2, likely, COUNT_UNKNOWN))->as_If();
 512   Node* then2   = gvn.transform(new IfTrueNode(iff2));
 513   Node* elsen2  = gvn.transform(new IfFalseNode(iff2));
 514 
 515   // redo CAS
 516   Node* cas2       = gvn.transform(new CompareAndSwapPNode(elsen2, kit->memory(alias_idx), in_adr, in_val, in_expected, cas->order()));
 517   Node* scmemproj2 = gvn.transform(new SCMemProjNode(cas2));
 518   kit->set_control(elsen2);
 519   kit->set_memory(scmemproj2, alias_idx);
 520 
 521   // Merge inner flow - check if healed oop was equal too expected.
 522   region2->set_req(1, kit->control());
 523   region2->set_req(2, then2);
 524   phi2->set_req(1, cas2);
 525   phi2->set_req(2, kit->intcon(0));
 526   phi_mem2->init_req(1, scmemproj2);
 527   kit->set_memory(phi_mem2, alias_idx);
 528 
 529   // Merge outer flow - then check if first cas succeded
 530   region->set_req(1, then);
 531   region->set_req(2, region2);
 532   phi->set_req(1, kit->intcon(1));
 533   phi->set_req(2, phi2);
 534   phi_mem->init_req(2, phi_mem2);
 535   kit->set_memory(phi_mem, alias_idx);
 536 
 537   gvn.transform(region2);
 538   gvn.transform(phi2);
 539   gvn.transform(phi_mem2);
 540   gvn.transform(region);
 541   gvn.transform(phi);
 542   gvn.transform(phi_mem);
 543 
 544   kit->set_control(region);
 545   kit->insert_mem_bar(Op_MemBarCPUOrder);
 546 
 547   return phi;
 548 }
 549 
 550 Node* ZBarrierSetC2::make_cmpx_loadbarrier(C2AtomicAccess& access) const {
 551   CompareAndExchangePNode* cmpx = (CompareAndExchangePNode*)access.raw_access();
 552   GraphKit* kit = access.kit();
 553   PhaseGVN& gvn = kit->gvn();
 554   Compile* C = Compile::current();
 555 
 556   Node* in_ctrl     = cmpx->in(MemNode::Control);
 557   Node* in_mem      = cmpx->in(MemNode::Memory);
 558   Node* in_adr      = cmpx->in(MemNode::Address);
 559   Node* in_val      = cmpx->in(MemNode::ValueIn);
 560   Node* in_expected = cmpx->in(LoadStoreConditionalNode::ExpectedIn);
 561 
 562   float likely                   = PROB_LIKELY(0.999);
 563 
 564   const TypePtr *adr_type        = cmpx->get_ptr_type();
 565   Compile::AliasType* alias_type = C->alias_type(adr_type);
 566   int alias_idx                  = C->get_alias_index(adr_type);
 567 
 568   // Outer check - true: continue, false: load and check
 569   Node* region  = new RegionNode(3);
 570   Node* phi     = new PhiNode(region, adr_type);
 571 
 572   // Inner check - is the healed ref equal to the expected
 573   Node* region2 = new RegionNode(3);
 574   Node* phi2    = new PhiNode(region2, adr_type);
 575 
 576   // Check if cmpx succeded
 577   Node* cmp     = gvn.transform(new CmpPNode(cmpx, in_expected));
 578   Node* bol     = gvn.transform(new BoolNode(cmp, BoolTest::eq))->as_Bool();
 579   IfNode* iff   = gvn.transform(new IfNode(in_ctrl, bol, likely, COUNT_UNKNOWN))->as_If();
 580   Node* then    = gvn.transform(new IfTrueNode(iff));
 581   Node* elsen   = gvn.transform(new IfFalseNode(iff));
 582 
 583   Node* scmemproj1  = gvn.transform(new SCMemProjNode(cmpx));
 584   kit->set_memory(scmemproj1, alias_idx);
 585 
 586   // CAS fail - reload and heal oop
 587   Node* reload      = kit->make_load(elsen, in_adr, TypeOopPtr::BOTTOM, T_OBJECT, MemNode::unordered);
 588   Node* barrier     = gvn.transform(new LoadBarrierNode(C, elsen, scmemproj1, reload, in_adr, false, true, false));
 589   Node* barrierctrl = gvn.transform(new ProjNode(barrier, LoadBarrierNode::Control));
 590   Node* barrierdata = gvn.transform(new ProjNode(barrier, LoadBarrierNode::Oop));
 591 
 592   // Check load
 593   Node* tmpX    = gvn.transform(new CastP2XNode(NULL, barrierdata));
 594   Node* in_expX = gvn.transform(new CastP2XNode(NULL, in_expected));
 595   Node* cmp2    = gvn.transform(new CmpXNode(tmpX, in_expX));
 596   Node *bol2    = gvn.transform(new BoolNode(cmp2, BoolTest::ne))->as_Bool();
 597   IfNode* iff2  = gvn.transform(new IfNode(barrierctrl, bol2, likely, COUNT_UNKNOWN))->as_If();
 598   Node* then2   = gvn.transform(new IfTrueNode(iff2));
 599   Node* elsen2  = gvn.transform(new IfFalseNode(iff2));
 600 
 601   // Redo CAS
 602   Node* cmpx2      = gvn.transform(new CompareAndExchangePNode(elsen2, kit->memory(alias_idx), in_adr, in_val, in_expected, adr_type, cmpx->get_ptr_type(), cmpx->order()));
 603   Node* scmemproj2 = gvn.transform(new SCMemProjNode(cmpx2));
 604   kit->set_control(elsen2);
 605   kit->set_memory(scmemproj2, alias_idx);
 606 
 607   // Merge inner flow - check if healed oop was equal too expected.
 608   region2->set_req(1, kit->control());
 609   region2->set_req(2, then2);
 610   phi2->set_req(1, cmpx2);
 611   phi2->set_req(2, barrierdata);
 612 
 613   // Merge outer flow - then check if first cas succeded
 614   region->set_req(1, then);
 615   region->set_req(2, region2);
 616   phi->set_req(1, cmpx);
 617   phi->set_req(2, phi2);
 618 
 619   gvn.transform(region2);
 620   gvn.transform(phi2);
 621   gvn.transform(region);
 622   gvn.transform(phi);
 623 
 624   kit->set_control(region);
 625   kit->set_memory(in_mem, alias_idx);
 626   kit->insert_mem_bar(Op_MemBarCPUOrder);
 627 
 628   return phi;
 629 }
 630 
 631 Node* ZBarrierSetC2::load_barrier(GraphKit* kit, Node* val, Node* adr, bool weak, bool writeback, bool oop_reload_allowed) const {
 632   PhaseGVN& gvn = kit->gvn();
 633   Node* barrier = new LoadBarrierNode(Compile::current(), kit->control(), kit->memory(TypeRawPtr::BOTTOM), val, adr, weak, writeback, oop_reload_allowed);
 634   Node* transformed_barrier = gvn.transform(barrier);
 635 
 636   if (transformed_barrier->is_LoadBarrier()) {
 637     if (barrier == transformed_barrier) {
 638       kit->set_control(gvn.transform(new ProjNode(barrier, LoadBarrierNode::Control)));
 639     }
 640     return gvn.transform(new ProjNode(transformed_barrier, LoadBarrierNode::Oop));
 641   } else {
 642     return val;
 643   }
 644 }
 645 
 646 static bool barrier_needed(C2Access access) {
 647   return ZBarrierSet::barrier_needed(access.decorators(), access.type());
 648 }
 649 
 650 Node* ZBarrierSetC2::load_at_resolved(C2Access& access, const Type* val_type) const {
 651   Node* p = BarrierSetC2::load_at_resolved(access, val_type);
 652   if (!barrier_needed(access)) {
 653     return p;
 654   }
 655 
 656   bool conc_root = (access.decorators() & IN_CONCURRENT_ROOT) != 0;
 657   bool weak = (access.decorators() & ON_WEAK_OOP_REF) != 0;
 658 
 659   GraphKit* kit = access.kit();
 660   PhaseGVN& gvn = kit->gvn();
 661   Node* adr = access.addr().node();
 662   Node* heap_base_oop = access.base();
 663   bool unsafe = (access.decorators() & C2_UNSAFE_ACCESS) != 0;
 664   if (unsafe) {
 665     if (!ZVerifyLoadBarriers) {
 666       p = load_barrier(kit, p, adr);
 667     } else {
 668       if (!TypePtr::NULL_PTR->higher_equal(gvn.type(heap_base_oop))) {
 669         p = load_barrier(kit, p, adr);
 670       } else {
 671         IdealKit ideal(kit);
 672         IdealVariable res(ideal);
 673 #define __ ideal.
 674         __ declarations_done();
 675         __ set(res, p);
 676         __ if_then(heap_base_oop, BoolTest::ne, kit->null(), PROB_UNLIKELY(0.999)); {
 677           kit->sync_kit(ideal);
 678           p = load_barrier(kit, p, adr);
 679           __ set(res, p);
 680           __ sync_kit(kit);
 681         } __ end_if();
 682         kit->final_sync(ideal);
 683         p = __ value(res);
 684 #undef __
 685       }
 686     }
 687     return p;
 688   } else {
 689     return load_barrier(access.kit(), p, access.addr().node(), weak, true, true);
 690   }
 691 }
 692 
 693 Node* ZBarrierSetC2::atomic_cmpxchg_val_at_resolved(C2AtomicAccess& access, Node* expected_val,
 694                                                     Node* new_val, const Type* val_type) const {
 695   Node* result = BarrierSetC2::atomic_cmpxchg_val_at_resolved(access, expected_val, new_val, val_type);
 696   if (!barrier_needed(access)) {
 697     return result;
 698   }
 699 
 700   access.set_needs_pinning(false);
 701   return make_cmpx_loadbarrier(access);
 702 }
 703 
 704 Node* ZBarrierSetC2::atomic_cmpxchg_bool_at_resolved(C2AtomicAccess& access, Node* expected_val,
 705                                                      Node* new_val, const Type* value_type) const {
 706   Node* result = BarrierSetC2::atomic_cmpxchg_bool_at_resolved(access, expected_val, new_val, value_type);
 707   if (!barrier_needed(access)) {
 708     return result;
 709   }
 710 
 711   Node* load_store = access.raw_access();
 712   bool weak_cas = (access.decorators() & C2_WEAK_CMPXCHG) != 0;
 713   bool expected_is_null = (expected_val->get_ptr_type() == TypePtr::NULL_PTR);
 714 
 715   if (!expected_is_null) {
 716     if (weak_cas) {
 717       access.set_needs_pinning(false);
 718       load_store = make_cas_loadbarrier(access);
 719     } else {
 720       access.set_needs_pinning(false);
 721       load_store = make_cas_loadbarrier(access);
 722     }
 723   }
 724 
 725   return load_store;
 726 }
 727 
 728 Node* ZBarrierSetC2::atomic_xchg_at_resolved(C2AtomicAccess& access, Node* new_val, const Type* val_type) const {
 729   Node* result = BarrierSetC2::atomic_xchg_at_resolved(access, new_val, val_type);
 730   if (!barrier_needed(access)) {
 731     return result;
 732   }
 733 
 734   Node* load_store = access.raw_access();
 735   Node* adr = access.addr().node();
 736 
 737   return load_barrier(access.kit(), load_store, adr, false, false, false);
 738 }
 739 
 740 // == Macro Expansion ==
 741 
 742 void ZBarrierSetC2::expand_loadbarrier_node(PhaseMacroExpand* phase, LoadBarrierNode* barrier) const {
 743   Node* in_ctrl = barrier->in(LoadBarrierNode::Control);
 744   Node* in_mem  = barrier->in(LoadBarrierNode::Memory);
 745   Node* in_val  = barrier->in(LoadBarrierNode::Oop);
 746   Node* in_adr  = barrier->in(LoadBarrierNode::Address);
 747 
 748   Node* out_ctrl = barrier->proj_out(LoadBarrierNode::Control);
 749   Node* out_res  = barrier->proj_out(LoadBarrierNode::Oop);
 750 
 751   PhaseIterGVN &igvn = phase->igvn();
 752 
 753   if (ZVerifyLoadBarriers) {
 754     igvn.replace_node(out_res, in_val);
 755     igvn.replace_node(out_ctrl, in_ctrl);
 756     return;
 757   }
 758 
 759   if (barrier->can_be_eliminated()) {
 760     // Clone and pin the load for this barrier below the dominating
 761     // barrier: the load cannot be allowed to float above the
 762     // dominating barrier
 763     Node* load = in_val;
 764 




 765     if (load->is_Load()) {
 766       Node* new_load = load->clone();
 767       Node* addp = new_load->in(MemNode::Address);
 768       assert(addp->is_AddP() || addp->is_Phi(), "bad address");
 769       Node* cast = new CastPPNode(addp, igvn.type(addp), true);
 770       Node* ctrl = NULL;
 771       Node* similar = barrier->in(LoadBarrierNode::Similar);
 772       if (similar->is_Phi()) {
 773         // already expanded
 774         ctrl = similar->in(0);
 775       } else {
 776         assert(similar->is_Proj() && similar->in(0)->is_LoadBarrier(), "unexpected graph shape");
 777         ctrl = similar->in(0)->as_LoadBarrier()->proj_out(LoadBarrierNode::Control);
 778       }
 779       assert(ctrl != NULL, "bad control");
 780       cast->set_req(0, ctrl);
 781       igvn.transform(cast);
 782       new_load->set_req(MemNode::Address, cast);
 783       igvn.transform(new_load);
 784 
 785       igvn.replace_node(out_res, new_load);







 786       igvn.replace_node(out_ctrl, in_ctrl);
 787       return;
 788     }
 789     // cannot eliminate
 790   }
 791 
 792   // There are two cases that require the basic loadbarrier
 793   // 1) When the writeback of a healed oop must be avoided (swap)
 794   // 2) When we must guarantee that no reload of is done (swap, cas, cmpx)
 795   if (!barrier->is_writeback()) {
 796     assert(!barrier->oop_reload_allowed(), "writeback barriers should be marked as requires oop");
 797   }
 798 
 799 #ifdef SPARC
 800   bool basic_load_barrier = true;
 801 #else
 802   bool basic_load_barrier = !barrier->oop_reload_allowed();
 803 #endif
 804 
 805   if (basic_load_barrier) {
 806     expand_loadbarrier_basic(phase, barrier);
 807   } else {
 808     expand_loadbarrier_optimized(phase, barrier);
 809   }
 810 }
 811 
 812 // Basic loadbarrier using conventional arg passing
 813 void ZBarrierSetC2::expand_loadbarrier_basic(PhaseMacroExpand* phase, LoadBarrierNode *barrier) const {
 814   PhaseIterGVN &igvn = phase->igvn();
 815 
 816   Node* in_ctrl = barrier->in(LoadBarrierNode::Control);
 817   Node* in_mem  = barrier->in(LoadBarrierNode::Memory);
 818   Node* in_val  = barrier->in(LoadBarrierNode::Oop);
 819   Node* in_adr  = barrier->in(LoadBarrierNode::Address);
 820 
 821   Node* out_ctrl = barrier->proj_out(LoadBarrierNode::Control);
 822   Node* out_res  = barrier->proj_out(LoadBarrierNode::Oop);
 823 
 824   float unlikely  = PROB_UNLIKELY(0.999);
 825   const Type* in_val_maybe_null_t = igvn.type(in_val);
 826 
 827 #ifdef SPARC
 828   Node* bad_mask = igvn.transform(new AddrBadBitNode());
 829 #else
 830   Node* jthread = igvn.transform(new ThreadLocalNode());
 831   Node* adr = phase->basic_plus_adr(jthread, in_bytes(ZThreadLocalData::address_bad_mask_offset()));
 832   Node* bad_mask = igvn.transform(LoadNode::make(igvn, in_ctrl, in_mem, adr, TypeRawPtr::BOTTOM, TypeX_X, TypeX_X->basic_type(), MemNode::unordered));
 833 #endif
 834   Node* cast = igvn.transform(new CastP2XNode(in_ctrl, in_val));
 835   Node* obj_masked = igvn.transform(new AndXNode(cast, bad_mask));
 836   Node* cmp = igvn.transform(new CmpXNode(obj_masked, igvn.zerocon(TypeX_X->basic_type())));
 837   Node *bol = igvn.transform(new BoolNode(cmp, BoolTest::ne))->as_Bool();
 838   IfNode* iff = igvn.transform(new IfNode(in_ctrl, bol, unlikely, COUNT_UNKNOWN))->as_If();
 839   Node* then = igvn.transform(new IfTrueNode(iff));
 840   Node* elsen = igvn.transform(new IfFalseNode(iff));
 841 
 842   Node* result_region;
 843   Node* result_val;
 844 
 845   result_region = new RegionNode(3);
 846   result_val = new PhiNode(result_region, TypeInstPtr::BOTTOM);
 847 
 848   result_region->set_req(1, elsen);
 849   Node* res = igvn.transform(new CastPPNode(in_val, in_val_maybe_null_t));
 850   res->init_req(0, elsen);
 851   result_val->set_req(1, res);
 852 
 853   const TypeFunc *tf = load_barrier_Type();
 854   Node* call;
 855   if (barrier->is_weak()) {
 856     call = new CallLeafNode(tf,
 857                             ZBarrierSetRuntime::load_barrier_on_weak_oop_field_preloaded_addr(),
 858                             "ZBarrierSetRuntime::load_barrier_on_weak_oop_field_preloaded",
 859                             TypeRawPtr::BOTTOM);
 860   } else {
 861     call = new CallLeafNode(tf,
 862                             ZBarrierSetRuntime::load_barrier_on_oop_field_preloaded_addr(),
 863                             "ZBarrierSetRuntime::load_barrier_on_oop_field_preloaded",
 864                             TypeRawPtr::BOTTOM);
 865   }
 866 
 867   call->init_req(TypeFunc::Control, then);
 868   call->init_req(TypeFunc::I_O    , phase->top());
 869   call->init_req(TypeFunc::Memory , in_mem);
 870   call->init_req(TypeFunc::FramePtr, phase->top());
 871   call->init_req(TypeFunc::ReturnAdr, phase->top());
 872   call->init_req(TypeFunc::Parms+0, in_val);
 873   if (barrier->is_writeback()) {
 874     call->init_req(TypeFunc::Parms+1, in_adr);
 875   } else {
 876     // when slow path is called with a null adr, the healed oop will not be written back
 877     call->init_req(TypeFunc::Parms+1, igvn.zerocon(T_OBJECT));
 878   }
 879   call = igvn.transform(call);
 880 
 881   Node* ctrl = igvn.transform(new ProjNode(call, TypeFunc::Control));
 882   res = igvn.transform(new ProjNode(call, TypeFunc::Parms));
 883   res = igvn.transform(new CheckCastPPNode(ctrl, res, in_val_maybe_null_t));
 884 
 885   result_region->set_req(2, ctrl);
 886   result_val->set_req(2, res);
 887 
 888   result_region = igvn.transform(result_region);
 889   result_val = igvn.transform(result_val);
 890 
 891   if (out_ctrl != NULL) { // added if cond
 892     igvn.replace_node(out_ctrl, result_region);
 893   }
 894   igvn.replace_node(out_res, result_val);
 895 }
 896 
 897 // Optimized, low spill, loadbarrier variant using stub specialized on register used
 898 void ZBarrierSetC2::expand_loadbarrier_optimized(PhaseMacroExpand* phase, LoadBarrierNode *barrier) const {
 899   PhaseIterGVN &igvn = phase->igvn();
 900 #ifdef PRINT_NODE_TRAVERSALS
 901   Node* preceding_barrier_node = barrier->in(LoadBarrierNode::Oop);
 902 #endif
 903 
 904   Node* in_ctrl = barrier->in(LoadBarrierNode::Control);
 905   Node* in_mem = barrier->in(LoadBarrierNode::Memory);
 906   Node* in_val = barrier->in(LoadBarrierNode::Oop);
 907   Node* in_adr = barrier->in(LoadBarrierNode::Address);
 908 
 909   Node* out_ctrl = barrier->proj_out(LoadBarrierNode::Control);
 910   Node* out_res = barrier->proj_out(LoadBarrierNode::Oop);
 911 
 912   assert(barrier->in(LoadBarrierNode::Oop) != NULL, "oop to loadbarrier node cannot be null");
 913 
 914 #ifdef PRINT_NODE_TRAVERSALS
 915   tty->print("\n\n\nBefore barrier optimization:\n");
 916   traverse(barrier, out_ctrl, out_res, -1);
 917 
 918   tty->print("\nBefore barrier optimization:  preceding_barrier_node\n");
 919   traverse(preceding_barrier_node, out_ctrl, out_res, -1);
 920 #endif
 921 
 922   float unlikely  = PROB_UNLIKELY(0.999);
 923 
 924   Node* jthread = igvn.transform(new ThreadLocalNode());
 925   Node* adr = phase->basic_plus_adr(jthread, in_bytes(ZThreadLocalData::address_bad_mask_offset()));
 926   Node* bad_mask = igvn.transform(LoadNode::make(igvn, in_ctrl, in_mem, adr,
 927                                                  TypeRawPtr::BOTTOM, TypeX_X, TypeX_X->basic_type(),
 928                                                  MemNode::unordered));
 929   Node* cast = igvn.transform(new CastP2XNode(in_ctrl, in_val));
 930   Node* obj_masked = igvn.transform(new AndXNode(cast, bad_mask));
 931   Node* cmp = igvn.transform(new CmpXNode(obj_masked, igvn.zerocon(TypeX_X->basic_type())));
 932   Node *bol = igvn.transform(new BoolNode(cmp, BoolTest::ne))->as_Bool();
 933   IfNode* iff = igvn.transform(new IfNode(in_ctrl, bol, unlikely, COUNT_UNKNOWN))->as_If();
 934   Node* then = igvn.transform(new IfTrueNode(iff));
 935   Node* elsen = igvn.transform(new IfFalseNode(iff));
 936 
 937   Node* slow_path_surrogate;
 938   if (!barrier->is_weak()) {
 939     slow_path_surrogate = igvn.transform(new LoadBarrierSlowRegNode(then, in_mem, in_adr, in_val->adr_type(),
 940                                                                     (const TypePtr*) in_val->bottom_type(), MemNode::unordered));
 941   } else {
 942     slow_path_surrogate = igvn.transform(new LoadBarrierWeakSlowRegNode(then, in_mem, in_adr, in_val->adr_type(),
 943                                                                         (const TypePtr*) in_val->bottom_type(), MemNode::unordered));
 944   }
 945 
 946   Node *new_loadp;
 947   new_loadp = slow_path_surrogate;
 948   // create the final region/phi pair to converge cntl/data paths to downstream code
 949   Node* result_region = igvn.transform(new RegionNode(3));
 950   result_region->set_req(1, then);
 951   result_region->set_req(2, elsen);
 952 
 953   Node* result_phi = igvn.transform(new PhiNode(result_region, TypeInstPtr::BOTTOM));
 954   result_phi->set_req(1, new_loadp);
 955   result_phi->set_req(2, barrier->in(LoadBarrierNode::Oop));
 956 
 957   // finally, connect the original outputs to the barrier region and phi to complete the expansion/substitution
 958   // igvn.replace_node(out_ctrl, result_region);
 959   if (out_ctrl != NULL) { // added if cond
 960     igvn.replace_node(out_ctrl, result_region);
 961   }
 962   igvn.replace_node(out_res, result_phi);
 963 
 964   assert(barrier->outcnt() == 0,"LoadBarrier macro node has non-null outputs after expansion!");
 965 
 966 #ifdef PRINT_NODE_TRAVERSALS
 967   tty->print("\nAfter barrier optimization:  old out_ctrl\n");
 968   traverse(out_ctrl, out_ctrl, out_res, -1);
 969   tty->print("\nAfter barrier optimization:  old out_res\n");
 970   traverse(out_res, out_ctrl, out_res, -1);
 971   tty->print("\nAfter barrier optimization:  old barrier\n");
 972   traverse(barrier, out_ctrl, out_res, -1);
 973   tty->print("\nAfter barrier optimization:  preceding_barrier_node\n");
 974   traverse(preceding_barrier_node, result_region, result_phi, -1);
 975 #endif
 976 
 977   return;
 978 }
 979 
 980 bool ZBarrierSetC2::expand_macro_nodes(PhaseMacroExpand* macro) const {
 981   Compile* C = Compile::current();
 982   PhaseIterGVN &igvn = macro->igvn();
 983   ZBarrierSetC2State* s = state();
 984   if (s->load_barrier_count() > 0) {
 985 #ifdef ASSERT
 986     verify_gc_barriers(false);
 987 #endif
 988     igvn.set_delay_transform(true);
 989     int skipped = 0;
 990     while (s->load_barrier_count() > skipped) {
 991       int load_barrier_count = s->load_barrier_count();
 992       LoadBarrierNode * n = s->load_barrier_node(load_barrier_count-1-skipped);
 993       if (igvn.type(n) == Type::TOP || (n->in(0) != NULL && n->in(0)->is_top())) {
 994         // node is unreachable, so don't try to expand it
 995         s->remove_load_barrier_node(n);
 996         continue;
 997       }
 998       if (!n->can_be_eliminated()) {
 999         skipped++;
1000         continue;
1001       }
1002       expand_loadbarrier_node(macro, n);
1003       assert(s->load_barrier_count() < load_barrier_count, "must have deleted a node from load barrier list");
1004       if (C->failing())  return true;
1005     }
1006     while (s->load_barrier_count() > 0) {
1007       int load_barrier_count = s->load_barrier_count();
1008       LoadBarrierNode* n = s->load_barrier_node(load_barrier_count - 1);
1009       assert(!(igvn.type(n) == Type::TOP || (n->in(0) != NULL && n->in(0)->is_top())), "should have been processed already");
1010       assert(!n->can_be_eliminated(), "should have been processed already");
1011       expand_loadbarrier_node(macro, n);
1012       assert(s->load_barrier_count() < load_barrier_count, "must have deleted a node from load barrier list");
1013       if (C->failing())  return true;
1014     }
1015     igvn.set_delay_transform(false);
1016     igvn.optimize();
1017     if (C->failing())  return true;
1018   }
1019   return false;
1020 }
1021 
1022 // == Loop optimization ==
1023 
1024 static bool replace_with_dominating_barrier(PhaseIdealLoop* phase, LoadBarrierNode* lb, bool last_round) {
1025   PhaseIterGVN &igvn = phase->igvn();
1026   Compile* C = Compile::current();
1027 
1028   LoadBarrierNode* lb2 = lb->has_dominating_barrier(phase, false, last_round);
1029   if (lb2 != NULL) {
1030     if (lb->in(LoadBarrierNode::Oop) != lb2->in(LoadBarrierNode::Oop)) {
1031       assert(lb->in(LoadBarrierNode::Address) == lb2->in(LoadBarrierNode::Address), "");
1032       igvn.replace_input_of(lb, LoadBarrierNode::Similar, lb2->proj_out(LoadBarrierNode::Oop));
1033       C->set_major_progress();
1034     } else  {
1035       // That transformation may cause the Similar edge on dominated load barriers to be invalid
1036       lb->fix_similar_in_uses(&igvn);
1037 
1038       Node* val = lb->proj_out(LoadBarrierNode::Oop);
1039       assert(lb2->has_true_uses(), "");
1040       assert(lb2->in(LoadBarrierNode::Oop) == lb->in(LoadBarrierNode::Oop), "");
1041 
1042       phase->lazy_update(lb, lb->in(LoadBarrierNode::Control));
1043       phase->lazy_replace(lb->proj_out(LoadBarrierNode::Control), lb->in(LoadBarrierNode::Control));
1044       igvn.replace_node(val, lb2->proj_out(LoadBarrierNode::Oop));
1045 
1046       return true;
1047     }
1048   }
1049   return false;
1050 }
1051 
1052 static Node* find_dominating_memory(PhaseIdealLoop* phase, Node* mem, Node* dom, int i) {
1053   assert(dom->is_Region() || i == -1, "");
1054   Node* m = mem;
1055   while(phase->is_dominator(dom, phase->has_ctrl(m) ? phase->get_ctrl(m) : m->in(0))) {
1056     if (m->is_Mem()) {
1057       assert(m->as_Mem()->adr_type() == TypeRawPtr::BOTTOM, "");
1058       m = m->in(MemNode::Memory);
1059     } else if (m->is_MergeMem()) {
1060       m = m->as_MergeMem()->memory_at(Compile::AliasIdxRaw);
1061     } else if (m->is_Phi()) {
1062       if (m->in(0) == dom && i != -1) {
1063         m = m->in(i);
1064         break;
1065       } else {
1066         m = m->in(LoopNode::EntryControl);
1067       }
1068     } else if (m->is_Proj()) {
1069       m = m->in(0);
1070     } else if (m->is_SafePoint() || m->is_MemBar()) {
1071       m = m->in(TypeFunc::Memory);
1072     } else {
1073 #ifdef ASSERT
1074       m->dump();
1075 #endif
1076       ShouldNotReachHere();
1077     }
1078   }
1079   return m;
1080 }
1081 
1082 static LoadBarrierNode* clone_load_barrier(PhaseIdealLoop* phase, LoadBarrierNode* lb, Node* ctl, Node* mem, Node* oop_in) {
1083   PhaseIterGVN &igvn = phase->igvn();
1084   Compile* C = Compile::current();
1085   Node* the_clone = lb->clone();
1086   the_clone->set_req(LoadBarrierNode::Control, ctl);
1087   the_clone->set_req(LoadBarrierNode::Memory, mem);
1088   if (oop_in != NULL) {
1089     the_clone->set_req(LoadBarrierNode::Oop, oop_in);
1090   }
1091 
1092   LoadBarrierNode* new_lb = the_clone->as_LoadBarrier();
1093   igvn.register_new_node_with_optimizer(new_lb);
1094   IdealLoopTree *loop = phase->get_loop(new_lb->in(0));
1095   phase->set_ctrl(new_lb, new_lb->in(0));
1096   phase->set_loop(new_lb, loop);
1097   phase->set_idom(new_lb, new_lb->in(0), phase->dom_depth(new_lb->in(0))+1);
1098   if (!loop->_child) {
1099     loop->_body.push(new_lb);
1100   }
1101 
1102   Node* proj_ctl = new ProjNode(new_lb, LoadBarrierNode::Control);
1103   igvn.register_new_node_with_optimizer(proj_ctl);
1104   phase->set_ctrl(proj_ctl, proj_ctl->in(0));
1105   phase->set_loop(proj_ctl, loop);
1106   phase->set_idom(proj_ctl, new_lb, phase->dom_depth(new_lb)+1);
1107   if (!loop->_child) {
1108     loop->_body.push(proj_ctl);
1109   }
1110 
1111   Node* proj_oop = new ProjNode(new_lb, LoadBarrierNode::Oop);
1112   phase->register_new_node(proj_oop, new_lb);
1113 
1114   if (!new_lb->in(LoadBarrierNode::Similar)->is_top()) {
1115     LoadBarrierNode* similar = new_lb->in(LoadBarrierNode::Similar)->in(0)->as_LoadBarrier();
1116     if (!phase->is_dominator(similar, ctl)) {
1117       igvn.replace_input_of(new_lb, LoadBarrierNode::Similar, C->top());
1118     }
1119   }
1120 
1121   return new_lb;
1122 }
1123 
1124 static void replace_barrier(PhaseIdealLoop* phase, LoadBarrierNode* lb, Node* new_val) {
1125   PhaseIterGVN &igvn = phase->igvn();
1126   Node* val = lb->proj_out(LoadBarrierNode::Oop);
1127   igvn.replace_node(val, new_val);
1128   phase->lazy_update(lb, lb->in(LoadBarrierNode::Control));
1129   phase->lazy_replace(lb->proj_out(LoadBarrierNode::Control), lb->in(LoadBarrierNode::Control));
1130 }
1131 
1132 static bool split_barrier_thru_phi(PhaseIdealLoop* phase, LoadBarrierNode* lb) {
1133   PhaseIterGVN &igvn = phase->igvn();
1134   Compile* C = Compile::current();
1135 
1136   if (lb->in(LoadBarrierNode::Oop)->is_Phi()) {
1137     Node* oop_phi = lb->in(LoadBarrierNode::Oop);
1138 
1139     if (oop_phi->req() == 2) {
1140       // Ignore phis with only one input
1141       return false;
1142     }
1143 
1144     if (phase->is_dominator(phase->get_ctrl(lb->in(LoadBarrierNode::Address)),
1145                             oop_phi->in(0)) && phase->get_ctrl(lb->in(LoadBarrierNode::Address)) != oop_phi->in(0)) {
1146       // That transformation may cause the Similar edge on dominated load barriers to be invalid
1147       lb->fix_similar_in_uses(&igvn);
1148 
1149       RegionNode* region = oop_phi->in(0)->as_Region();
1150 
1151       int backedge = LoopNode::LoopBackControl;
1152       if (region->is_Loop() && region->in(backedge)->is_Proj() && region->in(backedge)->in(0)->is_If()) {
1153         Node* c = region->in(backedge)->in(0)->in(0);
1154         assert(c->unique_ctrl_out() == region->in(backedge)->in(0), "");
1155         Node* oop = lb->in(LoadBarrierNode::Oop)->in(backedge);
1156         Node* oop_c = phase->has_ctrl(oop) ? phase->get_ctrl(oop) : oop;
1157         if (!phase->is_dominator(oop_c, c)) {
1158           return false;
1159         }
1160       }
1161 
1162       // If the node on the backedge above the phi is the node itself - we have a self loop.
1163       // Don't clone - this will be folded later.
1164       if (oop_phi->in(LoopNode::LoopBackControl) == lb->proj_out(LoadBarrierNode::Oop)) {
1165         return false;
1166       }
1167 
1168       bool is_strip_mined = region->is_CountedLoop() && region->as_CountedLoop()->is_strip_mined();
1169       Node *phi = oop_phi->clone();
1170 
1171       for (uint i = 1; i < region->req(); i++) {
1172         Node* ctrl = region->in(i);
1173         if (ctrl != C->top()) {
1174           assert(!phase->is_dominator(ctrl, region) || region->is_Loop(), "");
1175 
1176           Node* mem = lb->in(LoadBarrierNode::Memory);
1177           Node* m = find_dominating_memory(phase, mem, region, i);
1178 
1179           if (region->is_Loop() && i == LoopNode::LoopBackControl && ctrl->is_Proj() && ctrl->in(0)->is_If()) {
1180             ctrl = ctrl->in(0)->in(0);
1181           } else if (region->is_Loop() && is_strip_mined) {
1182             // If this is a strip mined loop, control must move above OuterStripMinedLoop
1183             assert(i == LoopNode::EntryControl, "check");
1184             assert(ctrl->is_OuterStripMinedLoop(), "sanity");
1185             ctrl = ctrl->as_OuterStripMinedLoop()->in(LoopNode::EntryControl);
1186           }
1187 
1188           LoadBarrierNode* new_lb = clone_load_barrier(phase, lb, ctrl, m, lb->in(LoadBarrierNode::Oop)->in(i));
1189           Node* out_ctrl = new_lb->proj_out(LoadBarrierNode::Control);
1190 
1191           if (is_strip_mined && (i == LoopNode::EntryControl)) {
1192             assert(region->in(i)->is_OuterStripMinedLoop(), "");
1193             igvn.replace_input_of(region->in(i), i, out_ctrl);
1194           } else if (ctrl == region->in(i)) {
1195             igvn.replace_input_of(region, i, out_ctrl);
1196           } else {
1197             Node* iff = region->in(i)->in(0);
1198             igvn.replace_input_of(iff, 0, out_ctrl);
1199             phase->set_idom(iff, out_ctrl, phase->dom_depth(out_ctrl)+1);
1200           }
1201           phi->set_req(i, new_lb->proj_out(LoadBarrierNode::Oop));
1202         }
1203       }
1204       phase->register_new_node(phi, region);
1205       replace_barrier(phase, lb, phi);
1206 
1207       if (region->is_Loop()) {
1208         // Load barrier moved to the back edge of the Loop may now
1209         // have a safepoint on the path to the barrier on the Similar
1210         // edge
1211         igvn.replace_input_of(phi->in(LoopNode::LoopBackControl)->in(0), LoadBarrierNode::Similar, C->top());
1212         Node* head = region->in(LoopNode::EntryControl);
1213         phase->set_idom(region, head, phase->dom_depth(head)+1);
1214         phase->recompute_dom_depth();
1215         if (head->is_CountedLoop() && head->as_CountedLoop()->is_main_loop()) {
1216           head->as_CountedLoop()->set_normal_loop();
1217         }
1218       }
1219 
1220       return true;
1221     }
1222   }
1223 
1224   return false;
1225 }
1226 
1227 static bool move_out_of_loop(PhaseIdealLoop* phase, LoadBarrierNode* lb) {
1228   PhaseIterGVN &igvn = phase->igvn();
1229   IdealLoopTree *lb_loop = phase->get_loop(lb->in(0));
1230   if (lb_loop != phase->ltree_root() && !lb_loop->_irreducible) {
1231     Node* oop_ctrl = phase->get_ctrl(lb->in(LoadBarrierNode::Oop));
1232     IdealLoopTree *oop_loop = phase->get_loop(oop_ctrl);
1233     IdealLoopTree* adr_loop = phase->get_loop(phase->get_ctrl(lb->in(LoadBarrierNode::Address)));
1234     if (!lb_loop->is_member(oop_loop) && !lb_loop->is_member(adr_loop)) {
1235       // That transformation may cause the Similar edge on dominated load barriers to be invalid
1236       lb->fix_similar_in_uses(&igvn);
1237 
1238       Node* head = lb_loop->_head;
1239       assert(head->is_Loop(), "");
1240 
1241       if (phase->is_dominator(head, oop_ctrl)) {
1242         assert(oop_ctrl->Opcode() == Op_CProj && oop_ctrl->in(0)->Opcode() == Op_NeverBranch, "");
1243         assert(lb_loop->is_member(phase->get_loop(oop_ctrl->in(0)->in(0))), "");
1244         return false;
1245       }
1246 
1247       if (head->is_CountedLoop()) {
1248         CountedLoopNode* cloop = head->as_CountedLoop();
1249         if (cloop->is_main_loop()) {
1250           cloop->set_normal_loop();
1251         }
1252         // When we are moving barrier out of a counted loop,
1253         // make sure we move it all the way out of the strip mined outer loop.
1254         if (cloop->is_strip_mined()) {
1255           head = cloop->outer_loop();
1256         }
1257       }
1258 
1259       Node* mem = lb->in(LoadBarrierNode::Memory);
1260       Node* m = find_dominating_memory(phase, mem, head, -1);
1261 
1262       LoadBarrierNode* new_lb = clone_load_barrier(phase, lb, head->in(LoopNode::EntryControl), m, NULL);
1263 
1264       assert(phase->idom(head) == head->in(LoopNode::EntryControl), "");
1265       Node* proj_ctl = new_lb->proj_out(LoadBarrierNode::Control);
1266       igvn.replace_input_of(head, LoopNode::EntryControl, proj_ctl);
1267       phase->set_idom(head, proj_ctl, phase->dom_depth(proj_ctl) + 1);
1268 
1269       replace_barrier(phase, lb, new_lb->proj_out(LoadBarrierNode::Oop));
1270 
1271       phase->recompute_dom_depth();
1272 
1273       return true;
1274     }
1275   }
1276 
1277   return false;
1278 }
1279 
1280 static bool common_barriers(PhaseIdealLoop* phase, LoadBarrierNode* lb) {
1281   PhaseIterGVN &igvn = phase->igvn();
1282   Node* in_val = lb->in(LoadBarrierNode::Oop);
1283   for (DUIterator_Fast imax, i = in_val->fast_outs(imax); i < imax; i++) {
1284     Node* u = in_val->fast_out(i);
1285     if (u != lb && u->is_LoadBarrier() && u->as_LoadBarrier()->has_true_uses()) {
1286       Node* this_ctrl = lb->in(LoadBarrierNode::Control);
1287       Node* other_ctrl = u->in(LoadBarrierNode::Control);
1288 
1289       Node* lca = phase->dom_lca(this_ctrl, other_ctrl);
1290       bool ok = true;
1291 
1292       Node* proj1 = NULL;
1293       Node* proj2 = NULL;
1294 
1295       while (this_ctrl != lca && ok) {
1296         if (this_ctrl->in(0) != NULL &&
1297             this_ctrl->in(0)->is_MultiBranch()) {
1298           if (this_ctrl->in(0)->in(0) == lca) {
1299             assert(proj1 == NULL, "");
1300             assert(this_ctrl->is_Proj(), "");
1301             proj1 = this_ctrl;
1302           } else if (!(this_ctrl->in(0)->is_If() && this_ctrl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none))) {
1303             ok = false;
1304           }
1305         }
1306         this_ctrl = phase->idom(this_ctrl);
1307       }
1308       while (other_ctrl != lca && ok) {
1309         if (other_ctrl->in(0) != NULL &&
1310             other_ctrl->in(0)->is_MultiBranch()) {
1311           if (other_ctrl->in(0)->in(0) == lca) {
1312             assert(other_ctrl->is_Proj(), "");
1313             assert(proj2 == NULL, "");
1314             proj2 = other_ctrl;
1315           } else if (!(other_ctrl->in(0)->is_If() && other_ctrl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none))) {
1316             ok = false;
1317           }
1318         }
1319         other_ctrl = phase->idom(other_ctrl);
1320       }
1321       assert(proj1 == NULL || proj2 == NULL || proj1->in(0) == proj2->in(0), "");
1322       if (ok && proj1 && proj2 && proj1 != proj2 && proj1->in(0)->is_If()) {
1323         // That transformation may cause the Similar edge on dominated load barriers to be invalid
1324         lb->fix_similar_in_uses(&igvn);
1325         u->as_LoadBarrier()->fix_similar_in_uses(&igvn);
1326 
1327         Node* split = lca->unique_ctrl_out();
1328         assert(split->in(0) == lca, "");
1329 
1330         Node* mem = lb->in(LoadBarrierNode::Memory);
1331         Node* m = find_dominating_memory(phase, mem, split, -1);
1332         LoadBarrierNode* new_lb = clone_load_barrier(phase, lb, lca, m, NULL);
1333 
1334         Node* proj_ctl = new_lb->proj_out(LoadBarrierNode::Control);
1335         igvn.replace_input_of(split, 0, new_lb->proj_out(LoadBarrierNode::Control));
1336         phase->set_idom(split, proj_ctl, phase->dom_depth(proj_ctl)+1);
1337 
1338         Node* proj_oop = new_lb->proj_out(LoadBarrierNode::Oop);
1339         replace_barrier(phase, lb, proj_oop);
1340         replace_barrier(phase, u->as_LoadBarrier(), proj_oop);
1341 
1342         phase->recompute_dom_depth();
1343 
1344         return true;
1345       }
1346     }
1347   }
1348 
1349   return false;
1350 }
1351 
1352 static void optimize_load_barrier(PhaseIdealLoop* phase, LoadBarrierNode* lb, bool last_round) {
1353   Compile* C = Compile::current();
1354 
1355   if (!C->directive()->ZOptimizeLoadBarriersOption) {
1356     return;
1357   }
1358 
1359   if (lb->has_true_uses()) {
1360     if (replace_with_dominating_barrier(phase, lb, last_round)) {
1361       return;
1362     }
1363 
1364     if (split_barrier_thru_phi(phase, lb)) {
1365       return;
1366     }
1367 
1368     if (move_out_of_loop(phase, lb)) {
1369       return;
1370     }
1371 
1372     if (common_barriers(phase, lb)) {
1373       return;
1374     }
1375   }
1376 }
1377 
1378 void ZBarrierSetC2::loop_optimize_gc_barrier(PhaseIdealLoop* phase, Node* node, bool last_round) {
1379   if (node->is_LoadBarrier()) {
1380     optimize_load_barrier(phase, node->as_LoadBarrier(), last_round);
1381   }
1382 }
1383 
1384 // == Verification ==
1385 
1386 #ifdef ASSERT
1387 
1388 static bool look_for_barrier(Node* n, bool post_parse, VectorSet& visited) {
1389   if (visited.test_set(n->_idx)) {
1390     return true;
1391   }
1392 
1393   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1394     Node* u = n->fast_out(i);
1395     if (u->is_LoadBarrier()) {
1396     } else if ((u->is_Phi() || u->is_CMove()) && !post_parse) {
1397       if (!look_for_barrier(u, post_parse, visited)) {
1398         return false;
1399       }
1400     } else if (u->Opcode() == Op_EncodeP || u->Opcode() == Op_DecodeN) {
1401       if (!look_for_barrier(u, post_parse, visited)) {
1402         return false;
1403       }
1404     } else if (u->Opcode() != Op_SCMemProj) {
1405       tty->print("bad use"); u->dump();
1406       return false;
1407     }
1408   }
1409 
1410   return true;
1411 }
1412 
1413 void ZBarrierSetC2::verify_gc_barriers(bool post_parse) const {
1414   ZBarrierSetC2State* s = state();
1415   Compile* C = Compile::current();
1416   ResourceMark rm;
1417   VectorSet visited(Thread::current()->resource_area());
1418   for (int i = 0; i < s->load_barrier_count(); i++) {
1419     LoadBarrierNode* n = s->load_barrier_node(i);
1420 
1421     // The dominating barrier on the same address if it exists and
1422     // this barrier must not be applied on the value from the same
1423     // load otherwise the value is not reloaded before it's used the
1424     // second time.
1425     assert(n->in(LoadBarrierNode::Similar)->is_top() ||
1426            (n->in(LoadBarrierNode::Similar)->in(0)->is_LoadBarrier() &&
1427             n->in(LoadBarrierNode::Similar)->in(0)->in(LoadBarrierNode::Address) == n->in(LoadBarrierNode::Address) &&
1428             n->in(LoadBarrierNode::Similar)->in(0)->in(LoadBarrierNode::Oop) != n->in(LoadBarrierNode::Oop)),
1429            "broken similar edge");
1430 
1431     assert(post_parse || n->as_LoadBarrier()->has_true_uses(),
1432            "found unneeded load barrier");
1433 
1434     // Several load barrier nodes chained through their Similar edge
1435     // break the code that remove the barriers in final graph reshape.
1436     assert(n->in(LoadBarrierNode::Similar)->is_top() ||
1437            (n->in(LoadBarrierNode::Similar)->in(0)->is_LoadBarrier() &&
1438             n->in(LoadBarrierNode::Similar)->in(0)->in(LoadBarrierNode::Similar)->is_top()),
1439            "chain of Similar load barriers");
1440 
1441     if (!n->in(LoadBarrierNode::Similar)->is_top()) {
1442       ResourceMark rm;
1443       Unique_Node_List wq;
1444       Node* other = n->in(LoadBarrierNode::Similar)->in(0);
1445       wq.push(n);
1446       bool ok = true;
1447       bool dom_found = false;
1448       for (uint next = 0; next < wq.size(); ++next) {
1449         Node *n = wq.at(next);
1450         assert(n->is_CFG(), "");
1451         assert(!n->is_SafePoint(), "");
1452 
1453         if (n == other) {
1454           continue;
1455         }
1456 
1457         if (n->is_Region()) {
1458           for (uint i = 1; i < n->req(); i++) {
1459             Node* m = n->in(i);
1460             if (m != NULL) {
1461               wq.push(m);
1462             }
1463           }
1464         } else {
1465           Node* m = n->in(0);
1466           if (m != NULL) {
1467             wq.push(m);
1468           }
1469         }
1470       }
1471     }
1472 
1473     if (ZVerifyLoadBarriers) {
1474       if ((n->is_Load() || n->is_LoadStore()) && n->bottom_type()->make_oopptr() != NULL) {
1475         visited.Clear();
1476         bool found = look_for_barrier(n, post_parse, visited);
1477         if (!found) {
1478           n->dump(1);
1479           n->dump(-3);
1480           stringStream ss;
1481           C->method()->print_short_name(&ss);
1482           tty->print_cr("-%s-", ss.as_string());
1483           assert(found, "");
1484         }
1485       }
1486     }
1487   }
1488 }
1489 
1490 #endif
--- EOF ---