1 /*
   2  * Copyright (c) 2015, 2019, Red Hat, Inc. 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 
  27 #include "classfile/javaClasses.hpp"
  28 #include "gc/shenandoah/c2/shenandoahSupport.hpp"
  29 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
  30 #include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"
  31 #include "gc/shenandoah/shenandoahForwarding.hpp"
  32 #include "gc/shenandoah/shenandoahHeap.hpp"
  33 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
  34 #include "gc/shenandoah/shenandoahRuntime.hpp"
  35 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
  36 #include "opto/arraycopynode.hpp"
  37 #include "opto/block.hpp"
  38 #include "opto/callnode.hpp"
  39 #include "opto/castnode.hpp"
  40 #include "opto/movenode.hpp"
  41 #include "opto/phaseX.hpp"
  42 #include "opto/rootnode.hpp"
  43 #include "opto/runtime.hpp"
  44 #include "opto/subnode.hpp"
  45 
  46 bool ShenandoahBarrierC2Support::expand(Compile* C, PhaseIterGVN& igvn) {
  47   ShenandoahBarrierSetC2State* state = ShenandoahBarrierSetC2::bsc2()->state();
  48   if ((state->enqueue_barriers_count() +
  49        state->load_reference_barriers_count()) > 0) {
  50     bool attempt_more_loopopts = ShenandoahLoopOptsAfterExpansion;
  51     C->clear_major_progress();
  52     PhaseIdealLoop ideal_loop(igvn, LoopOptsShenandoahExpand);
  53     if (C->failing()) return false;
  54     PhaseIdealLoop::verify(igvn);
  55     DEBUG_ONLY(verify_raw_mem(C->root());)
  56     if (attempt_more_loopopts) {
  57       C->set_major_progress();
  58       if (!C->optimize_loops(igvn, LoopOptsShenandoahPostExpand)) {
  59         return false;
  60       }
  61       C->clear_major_progress();
  62       if (C->range_check_cast_count() > 0) {
  63         // No more loop optimizations. Remove all range check dependent CastIINodes.
  64         C->remove_range_check_casts(igvn);
  65         igvn.optimize();
  66       }
  67     }
  68   }
  69   return true;
  70 }
  71 
  72 bool ShenandoahBarrierC2Support::is_gc_state_test(Node* iff, int mask) {
  73   if (!UseShenandoahGC) {
  74     return false;
  75   }
  76   assert(iff->is_If(), "bad input");
  77   if (iff->Opcode() != Op_If) {
  78     return false;
  79   }
  80   Node* bol = iff->in(1);
  81   if (!bol->is_Bool() || bol->as_Bool()->_test._test != BoolTest::ne) {
  82     return false;
  83   }
  84   Node* cmp = bol->in(1);
  85   if (cmp->Opcode() != Op_CmpI) {
  86     return false;
  87   }
  88   Node* in1 = cmp->in(1);
  89   Node* in2 = cmp->in(2);
  90   if (in2->find_int_con(-1) != 0) {
  91     return false;
  92   }
  93   if (in1->Opcode() != Op_AndI) {
  94     return false;
  95   }
  96   in2 = in1->in(2);
  97   if (in2->find_int_con(-1) != mask) {
  98     return false;
  99   }
 100   in1 = in1->in(1);
 101 
 102   return is_gc_state_load(in1);
 103 }
 104 
 105 bool ShenandoahBarrierC2Support::is_heap_stable_test(Node* iff) {
 106   return is_gc_state_test(iff, ShenandoahHeap::HAS_FORWARDED);
 107 }
 108 
 109 bool ShenandoahBarrierC2Support::is_gc_state_load(Node *n) {
 110   if (!UseShenandoahGC) {
 111     return false;
 112   }
 113   if (n->Opcode() != Op_LoadB && n->Opcode() != Op_LoadUB) {
 114     return false;
 115   }
 116   Node* addp = n->in(MemNode::Address);
 117   if (!addp->is_AddP()) {
 118     return false;
 119   }
 120   Node* base = addp->in(AddPNode::Address);
 121   Node* off = addp->in(AddPNode::Offset);
 122   if (base->Opcode() != Op_ThreadLocal) {
 123     return false;
 124   }
 125   if (off->find_intptr_t_con(-1) != in_bytes(ShenandoahThreadLocalData::gc_state_offset())) {
 126     return false;
 127   }
 128   return true;
 129 }
 130 
 131 bool ShenandoahBarrierC2Support::has_safepoint_between(Node* start, Node* stop, PhaseIdealLoop *phase) {
 132   assert(phase->is_dominator(stop, start), "bad inputs");
 133   ResourceMark rm;
 134   Unique_Node_List wq;
 135   wq.push(start);
 136   for (uint next = 0; next < wq.size(); next++) {
 137     Node *m = wq.at(next);
 138     if (m == stop) {
 139       continue;
 140     }
 141     if (m->is_SafePoint() && !m->is_CallLeaf()) {
 142       return true;
 143     }
 144     if (m->is_Region()) {
 145       for (uint i = 1; i < m->req(); i++) {
 146         wq.push(m->in(i));
 147       }
 148     } else {
 149       wq.push(m->in(0));
 150     }
 151   }
 152   return false;
 153 }
 154 
 155 #ifdef ASSERT
 156 bool ShenandoahBarrierC2Support::verify_helper(Node* in, Node_Stack& phis, VectorSet& visited, verify_type t, bool trace, Unique_Node_List& barriers_used) {
 157   assert(phis.size() == 0, "");
 158 
 159   while (true) {
 160     if (in->bottom_type() == TypePtr::NULL_PTR) {
 161       if (trace) {tty->print_cr("NULL");}
 162     } else if (!in->bottom_type()->make_ptr()->make_oopptr()) {
 163       if (trace) {tty->print_cr("Non oop");}
 164     } else {
 165       if (in->is_ConstraintCast()) {
 166         in = in->in(1);
 167         continue;
 168       } else if (in->is_AddP()) {
 169         assert(!in->in(AddPNode::Address)->is_top(), "no raw memory access");
 170         in = in->in(AddPNode::Address);
 171         continue;
 172       } else if (in->is_Con()) {
 173         if (trace) {
 174           tty->print("Found constant");
 175           in->dump();
 176         }
 177       } else if (in->Opcode() == Op_Parm) {
 178         if (trace) {
 179           tty->print("Found argument");
 180         }
 181       } else if (in->Opcode() == Op_CreateEx) {
 182         if (trace) {
 183           tty->print("Found create-exception");
 184         }
 185       } else if (in->Opcode() == Op_LoadP && in->adr_type() == TypeRawPtr::BOTTOM) {
 186         if (trace) {
 187           tty->print("Found raw LoadP (OSR argument?)");
 188         }
 189       } else if (in->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
 190         if (t == ShenandoahOopStore) {
 191           uint i = 0;
 192           for (; i < phis.size(); i++) {
 193             Node* n = phis.node_at(i);
 194             if (n->Opcode() == Op_ShenandoahEnqueueBarrier) {
 195               break;
 196             }
 197           }
 198           if (i == phis.size()) {
 199             return false;
 200           }
 201         }
 202         barriers_used.push(in);
 203         if (trace) {tty->print("Found barrier"); in->dump();}
 204       } else if (in->Opcode() == Op_ShenandoahEnqueueBarrier) {
 205         if (t != ShenandoahOopStore) {
 206           in = in->in(1);
 207           continue;
 208         }
 209         if (trace) {tty->print("Found enqueue barrier"); in->dump();}
 210         phis.push(in, in->req());
 211         in = in->in(1);
 212         continue;
 213       } else if (in->is_Proj() && in->in(0)->is_Allocate()) {
 214         if (trace) {
 215           tty->print("Found alloc");
 216           in->in(0)->dump();
 217         }
 218       } else if (in->is_Proj() && (in->in(0)->Opcode() == Op_CallStaticJava || in->in(0)->Opcode() == Op_CallDynamicJava)) {
 219         if (trace) {
 220           tty->print("Found Java call");
 221         }
 222       } else if (in->is_Phi()) {
 223         if (!visited.test_set(in->_idx)) {
 224           if (trace) {tty->print("Pushed phi:"); in->dump();}
 225           phis.push(in, 2);
 226           in = in->in(1);
 227           continue;
 228         }
 229         if (trace) {tty->print("Already seen phi:"); in->dump();}
 230       } else if (in->Opcode() == Op_CMoveP || in->Opcode() == Op_CMoveN) {
 231         if (!visited.test_set(in->_idx)) {
 232           if (trace) {tty->print("Pushed cmovep:"); in->dump();}
 233           phis.push(in, CMoveNode::IfTrue);
 234           in = in->in(CMoveNode::IfFalse);
 235           continue;
 236         }
 237         if (trace) {tty->print("Already seen cmovep:"); in->dump();}
 238       } else if (in->Opcode() == Op_EncodeP || in->Opcode() == Op_DecodeN) {
 239         in = in->in(1);
 240         continue;
 241       } else {
 242         return false;
 243       }
 244     }
 245     bool cont = false;
 246     while (phis.is_nonempty()) {
 247       uint idx = phis.index();
 248       Node* phi = phis.node();
 249       if (idx >= phi->req()) {
 250         if (trace) {tty->print("Popped phi:"); phi->dump();}
 251         phis.pop();
 252         continue;
 253       }
 254       if (trace) {tty->print("Next entry(%d) for phi:", idx); phi->dump();}
 255       in = phi->in(idx);
 256       phis.set_index(idx+1);
 257       cont = true;
 258       break;
 259     }
 260     if (!cont) {
 261       break;
 262     }
 263   }
 264   return true;
 265 }
 266 
 267 void ShenandoahBarrierC2Support::report_verify_failure(const char* msg, Node* n1, Node* n2) {
 268   if (n1 != NULL) {
 269     n1->dump(+10);
 270   }
 271   if (n2 != NULL) {
 272     n2->dump(+10);
 273   }
 274   fatal("%s", msg);
 275 }
 276 
 277 void ShenandoahBarrierC2Support::verify(RootNode* root) {
 278   ResourceMark rm;
 279   Unique_Node_List wq;
 280   GrowableArray<Node*> barriers;
 281   Unique_Node_List barriers_used;
 282   Node_Stack phis(0);
 283   VectorSet visited;
 284   const bool trace = false;
 285   const bool verify_no_useless_barrier = false;
 286 
 287   wq.push(root);
 288   for (uint next = 0; next < wq.size(); next++) {
 289     Node *n = wq.at(next);
 290     if (n->is_Load()) {
 291       const bool trace = false;
 292       if (trace) {tty->print("Verifying"); n->dump();}
 293       if (n->Opcode() == Op_LoadRange || n->Opcode() == Op_LoadKlass || n->Opcode() == Op_LoadNKlass) {
 294         if (trace) {tty->print_cr("Load range/klass");}
 295       } else {
 296         const TypePtr* adr_type = n->as_Load()->adr_type();
 297 
 298         if (adr_type->isa_oopptr() && adr_type->is_oopptr()->offset() == oopDesc::mark_offset_in_bytes()) {
 299           if (trace) {tty->print_cr("Mark load");}
 300         } else if (adr_type->isa_instptr() &&
 301                    adr_type->is_instptr()->klass()->is_subtype_of(Compile::current()->env()->Reference_klass()) &&
 302                    adr_type->is_instptr()->offset() == java_lang_ref_Reference::referent_offset()) {
 303           if (trace) {tty->print_cr("Reference.get()");}
 304         } else if (!verify_helper(n->in(MemNode::Address), phis, visited, ShenandoahLoad, trace, barriers_used)) {
 305           report_verify_failure("Shenandoah verification: Load should have barriers", n);
 306         }
 307       }
 308     } else if (n->is_Store()) {
 309       const bool trace = false;
 310 
 311       if (trace) {tty->print("Verifying"); n->dump();}
 312       if (n->in(MemNode::ValueIn)->bottom_type()->make_oopptr()) {
 313         Node* adr = n->in(MemNode::Address);
 314         bool verify = true;
 315 
 316         if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top()) {
 317           adr = adr->in(AddPNode::Address);
 318           if (adr->is_AddP()) {
 319             assert(adr->in(AddPNode::Base)->is_top(), "");
 320             adr = adr->in(AddPNode::Address);
 321             if (adr->Opcode() == Op_LoadP &&
 322                 adr->in(MemNode::Address)->in(AddPNode::Base)->is_top() &&
 323                 adr->in(MemNode::Address)->in(AddPNode::Address)->Opcode() == Op_ThreadLocal &&
 324                 adr->in(MemNode::Address)->in(AddPNode::Offset)->find_intptr_t_con(-1) == in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset())) {
 325               if (trace) {tty->print_cr("SATB prebarrier");}
 326               verify = false;
 327             }
 328           }
 329         }
 330 
 331         if (verify && !verify_helper(n->in(MemNode::ValueIn), phis, visited, ShenandoahStoreValEnqueueBarrier ? ShenandoahOopStore : ShenandoahValue, trace, barriers_used)) {
 332           report_verify_failure("Shenandoah verification: Store should have barriers", n);
 333         }
 334       }
 335       if (!verify_helper(n->in(MemNode::Address), phis, visited, ShenandoahStore, trace, barriers_used)) {
 336         report_verify_failure("Shenandoah verification: Store (address) should have barriers", n);
 337       }
 338     } else if (n->Opcode() == Op_CmpP) {
 339       const bool trace = false;
 340 
 341       Node* in1 = n->in(1);
 342       Node* in2 = n->in(2);
 343       if (in1->bottom_type()->isa_oopptr()) {
 344         if (trace) {tty->print("Verifying"); n->dump();}
 345 
 346         bool mark_inputs = false;
 347         if (in1->bottom_type() == TypePtr::NULL_PTR || in2->bottom_type() == TypePtr::NULL_PTR ||
 348             (in1->is_Con() || in2->is_Con())) {
 349           if (trace) {tty->print_cr("Comparison against a constant");}
 350           mark_inputs = true;
 351         } else if ((in1->is_CheckCastPP() && in1->in(1)->is_Proj() && in1->in(1)->in(0)->is_Allocate()) ||
 352                    (in2->is_CheckCastPP() && in2->in(1)->is_Proj() && in2->in(1)->in(0)->is_Allocate())) {
 353           if (trace) {tty->print_cr("Comparison with newly alloc'ed object");}
 354           mark_inputs = true;
 355         } else {
 356           assert(in2->bottom_type()->isa_oopptr(), "");
 357 
 358           if (!verify_helper(in1, phis, visited, ShenandoahStore, trace, barriers_used) ||
 359               !verify_helper(in2, phis, visited, ShenandoahStore, trace, barriers_used)) {
 360             report_verify_failure("Shenandoah verification: Cmp should have barriers", n);
 361           }
 362         }
 363         if (verify_no_useless_barrier &&
 364             mark_inputs &&
 365             (!verify_helper(in1, phis, visited, ShenandoahValue, trace, barriers_used) ||
 366              !verify_helper(in2, phis, visited, ShenandoahValue, trace, barriers_used))) {
 367           phis.clear();
 368           visited.reset();
 369         }
 370       }
 371     } else if (n->is_LoadStore()) {
 372       if (n->in(MemNode::ValueIn)->bottom_type()->make_ptr() &&
 373           !verify_helper(n->in(MemNode::ValueIn), phis, visited, ShenandoahStoreValEnqueueBarrier ? ShenandoahOopStore : ShenandoahValue, trace, barriers_used)) {
 374         report_verify_failure("Shenandoah verification: LoadStore (value) should have barriers", n);
 375       }
 376 
 377       if (n->in(MemNode::Address)->bottom_type()->make_oopptr() && !verify_helper(n->in(MemNode::Address), phis, visited, ShenandoahStore, trace, barriers_used)) {
 378         report_verify_failure("Shenandoah verification: LoadStore (address) should have barriers", n);
 379       }
 380     } else if (n->Opcode() == Op_CallLeafNoFP || n->Opcode() == Op_CallLeaf) {
 381       CallNode* call = n->as_Call();
 382 
 383       static struct {
 384         const char* name;
 385         struct {
 386           int pos;
 387           verify_type t;
 388         } args[6];
 389       } calls[] = {
 390         "aescrypt_encryptBlock",
 391         { { TypeFunc::Parms, ShenandoahLoad },   { TypeFunc::Parms+1, ShenandoahStore },  { TypeFunc::Parms+2, ShenandoahLoad },
 392           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 393         "aescrypt_decryptBlock",
 394         { { TypeFunc::Parms, ShenandoahLoad },   { TypeFunc::Parms+1, ShenandoahStore },  { TypeFunc::Parms+2, ShenandoahLoad },
 395           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 396         "multiplyToLen",
 397         { { TypeFunc::Parms, ShenandoahLoad },   { TypeFunc::Parms+2, ShenandoahLoad },   { TypeFunc::Parms+4, ShenandoahStore },
 398           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 399         "squareToLen",
 400         { { TypeFunc::Parms, ShenandoahLoad },   { TypeFunc::Parms+2, ShenandoahLoad },   { -1,  ShenandoahNone},
 401           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 402         "montgomery_multiply",
 403         { { TypeFunc::Parms, ShenandoahLoad },   { TypeFunc::Parms+1, ShenandoahLoad },   { TypeFunc::Parms+2, ShenandoahLoad },
 404           { TypeFunc::Parms+6, ShenandoahStore }, { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 405         "montgomery_square",
 406         { { TypeFunc::Parms, ShenandoahLoad },   { TypeFunc::Parms+1, ShenandoahLoad },   { TypeFunc::Parms+5, ShenandoahStore },
 407           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 408         "mulAdd",
 409         { { TypeFunc::Parms, ShenandoahStore },  { TypeFunc::Parms+1, ShenandoahLoad },   { -1,  ShenandoahNone},
 410           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 411         "vectorizedMismatch",
 412         { { TypeFunc::Parms, ShenandoahLoad },   { TypeFunc::Parms+1, ShenandoahLoad },   { -1,  ShenandoahNone},
 413           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 414         "updateBytesCRC32",
 415         { { TypeFunc::Parms+1, ShenandoahLoad }, { -1,  ShenandoahNone},                  { -1,  ShenandoahNone},
 416           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 417         "updateBytesAdler32",
 418         { { TypeFunc::Parms+1, ShenandoahLoad }, { -1,  ShenandoahNone},                  { -1,  ShenandoahNone},
 419           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 420         "updateBytesCRC32C",
 421         { { TypeFunc::Parms+1, ShenandoahLoad }, { TypeFunc::Parms+3, ShenandoahLoad},    { -1,  ShenandoahNone},
 422           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 423         "counterMode_AESCrypt",
 424         { { TypeFunc::Parms, ShenandoahLoad },   { TypeFunc::Parms+1, ShenandoahStore },  { TypeFunc::Parms+2, ShenandoahLoad },
 425           { TypeFunc::Parms+3, ShenandoahStore }, { TypeFunc::Parms+5, ShenandoahStore }, { TypeFunc::Parms+6, ShenandoahStore } },
 426         "cipherBlockChaining_encryptAESCrypt",
 427         { { TypeFunc::Parms, ShenandoahLoad },   { TypeFunc::Parms+1, ShenandoahStore },  { TypeFunc::Parms+2, ShenandoahLoad },
 428           { TypeFunc::Parms+3, ShenandoahLoad },  { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 429         "cipherBlockChaining_decryptAESCrypt",
 430         { { TypeFunc::Parms, ShenandoahLoad },   { TypeFunc::Parms+1, ShenandoahStore },  { TypeFunc::Parms+2, ShenandoahLoad },
 431           { TypeFunc::Parms+3, ShenandoahLoad },  { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 432         "shenandoah_clone_barrier",
 433         { { TypeFunc::Parms, ShenandoahLoad },   { -1,  ShenandoahNone},                  { -1,  ShenandoahNone},
 434           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 435         "ghash_processBlocks",
 436         { { TypeFunc::Parms, ShenandoahStore },  { TypeFunc::Parms+1, ShenandoahLoad },   { TypeFunc::Parms+2, ShenandoahLoad },
 437           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 438         "sha1_implCompress",
 439         { { TypeFunc::Parms, ShenandoahLoad },  { TypeFunc::Parms+1, ShenandoahStore },   { -1, ShenandoahNone },
 440           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 441         "sha256_implCompress",
 442         { { TypeFunc::Parms, ShenandoahLoad },  { TypeFunc::Parms+1, ShenandoahStore },   { -1, ShenandoahNone },
 443           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 444         "sha512_implCompress",
 445         { { TypeFunc::Parms, ShenandoahLoad },  { TypeFunc::Parms+1, ShenandoahStore },   { -1, ShenandoahNone },
 446           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 447         "sha1_implCompressMB",
 448         { { TypeFunc::Parms, ShenandoahLoad },  { TypeFunc::Parms+1, ShenandoahStore },   { -1, ShenandoahNone },
 449           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 450         "sha256_implCompressMB",
 451         { { TypeFunc::Parms, ShenandoahLoad },  { TypeFunc::Parms+1, ShenandoahStore },   { -1, ShenandoahNone },
 452           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 453         "sha512_implCompressMB",
 454         { { TypeFunc::Parms, ShenandoahLoad },  { TypeFunc::Parms+1, ShenandoahStore },   { -1, ShenandoahNone },
 455           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 456         "encodeBlock",
 457         { { TypeFunc::Parms, ShenandoahLoad },  { TypeFunc::Parms+3, ShenandoahStore },   { -1, ShenandoahNone },
 458           { -1,  ShenandoahNone},                 { -1,  ShenandoahNone},                 { -1,  ShenandoahNone} },
 459       };
 460 
 461       if (call->is_call_to_arraycopystub()) {
 462         Node* dest = NULL;
 463         const TypeTuple* args = n->as_Call()->_tf->domain_sig();
 464         for (uint i = TypeFunc::Parms, j = 0; i < args->cnt(); i++) {
 465           if (args->field_at(i)->isa_ptr()) {
 466             j++;
 467             if (j == 2) {
 468               dest = n->in(i);
 469               break;
 470             }
 471           }
 472         }
 473         if (!verify_helper(n->in(TypeFunc::Parms), phis, visited, ShenandoahLoad, trace, barriers_used) ||
 474             !verify_helper(dest, phis, visited, ShenandoahStore, trace, barriers_used)) {
 475           report_verify_failure("Shenandoah verification: ArrayCopy should have barriers", n);
 476         }
 477       } else if (strlen(call->_name) > 5 &&
 478                  !strcmp(call->_name + strlen(call->_name) - 5, "_fill")) {
 479         if (!verify_helper(n->in(TypeFunc::Parms), phis, visited, ShenandoahStore, trace, barriers_used)) {
 480           report_verify_failure("Shenandoah verification: _fill should have barriers", n);
 481         }
 482       } else if (!strcmp(call->_name, "shenandoah_wb_pre")) {
 483         // skip
 484       } else {
 485         const int calls_len = sizeof(calls) / sizeof(calls[0]);
 486         int i = 0;
 487         for (; i < calls_len; i++) {
 488           if (!strcmp(calls[i].name, call->_name)) {
 489             break;
 490           }
 491         }
 492         if (i != calls_len) {
 493           const uint args_len = sizeof(calls[0].args) / sizeof(calls[0].args[0]);
 494           for (uint j = 0; j < args_len; j++) {
 495             int pos = calls[i].args[j].pos;
 496             if (pos == -1) {
 497               break;
 498             }
 499             if (!verify_helper(call->in(pos), phis, visited, calls[i].args[j].t, trace, barriers_used)) {
 500               report_verify_failure("Shenandoah verification: intrinsic calls should have barriers", n);
 501             }
 502           }
 503           for (uint j = TypeFunc::Parms; j < call->req(); j++) {
 504             if (call->in(j)->bottom_type()->make_ptr() &&
 505                 call->in(j)->bottom_type()->make_ptr()->isa_oopptr()) {
 506               uint k = 0;
 507               for (; k < args_len && calls[i].args[k].pos != (int)j; k++);
 508               if (k == args_len) {
 509                 fatal("arg %d for call %s not covered", j, call->_name);
 510               }
 511             }
 512           }
 513         } else {
 514           for (uint j = TypeFunc::Parms; j < call->req(); j++) {
 515             if (call->in(j)->bottom_type()->make_ptr() &&
 516                 call->in(j)->bottom_type()->make_ptr()->isa_oopptr()) {
 517               fatal("%s not covered", call->_name);
 518             }
 519           }
 520         }
 521       }
 522     } else if (n->Opcode() == Op_ShenandoahEnqueueBarrier || n->Opcode() == Op_ShenandoahLoadReferenceBarrier) {
 523       // skip
 524     } else if (n->is_AddP()
 525                || n->is_Phi()
 526                || n->is_ConstraintCast()
 527                || n->Opcode() == Op_Return
 528                || n->Opcode() == Op_CMoveP
 529                || n->Opcode() == Op_CMoveN
 530                || n->Opcode() == Op_Rethrow
 531                || n->is_MemBar()
 532                || n->Opcode() == Op_Conv2B
 533                || n->Opcode() == Op_SafePoint
 534                || n->is_CallJava()
 535                || n->Opcode() == Op_Unlock
 536                || n->Opcode() == Op_EncodeP
 537                || n->Opcode() == Op_DecodeN) {
 538       // nothing to do
 539     } else {
 540       static struct {
 541         int opcode;
 542         struct {
 543           int pos;
 544           verify_type t;
 545         } inputs[2];
 546       } others[] = {
 547         Op_FastLock,
 548         { { 1, ShenandoahLoad },                  { -1, ShenandoahNone} },
 549         Op_Lock,
 550         { { TypeFunc::Parms, ShenandoahLoad },    { -1, ShenandoahNone} },
 551         Op_ArrayCopy,
 552         { { ArrayCopyNode::Src, ShenandoahLoad }, { ArrayCopyNode::Dest, ShenandoahStore } },
 553         Op_StrCompressedCopy,
 554         { { 2, ShenandoahLoad },                  { 3, ShenandoahStore } },
 555         Op_StrInflatedCopy,
 556         { { 2, ShenandoahLoad },                  { 3, ShenandoahStore } },
 557         Op_AryEq,
 558         { { 2, ShenandoahLoad },                  { 3, ShenandoahLoad } },
 559         Op_StrIndexOf,
 560         { { 2, ShenandoahLoad },                  { 4, ShenandoahLoad } },
 561         Op_StrComp,
 562         { { 2, ShenandoahLoad },                  { 4, ShenandoahLoad } },
 563         Op_StrEquals,
 564         { { 2, ShenandoahLoad },                  { 3, ShenandoahLoad } },
 565         Op_EncodeISOArray,
 566         { { 2, ShenandoahLoad },                  { 3, ShenandoahStore } },
 567         Op_HasNegatives,
 568         { { 2, ShenandoahLoad },                  { -1, ShenandoahNone} },
 569         Op_CastP2X,
 570         { { 1, ShenandoahLoad },                  { -1, ShenandoahNone} },
 571         Op_StrIndexOfChar,
 572         { { 2, ShenandoahLoad },                  { -1, ShenandoahNone } },
 573       };
 574 
 575       const int others_len = sizeof(others) / sizeof(others[0]);
 576       int i = 0;
 577       for (; i < others_len; i++) {
 578         if (others[i].opcode == n->Opcode()) {
 579           break;
 580         }
 581       }
 582       uint stop = n->is_Call() ? n->as_Call()->tf()->domain_sig()->cnt() : n->req();
 583       if (i != others_len) {
 584         const uint inputs_len = sizeof(others[0].inputs) / sizeof(others[0].inputs[0]);
 585         for (uint j = 0; j < inputs_len; j++) {
 586           int pos = others[i].inputs[j].pos;
 587           if (pos == -1) {
 588             break;
 589           }
 590           if (!verify_helper(n->in(pos), phis, visited, others[i].inputs[j].t, trace, barriers_used)) {
 591             report_verify_failure("Shenandoah verification: intrinsic calls should have barriers", n);
 592           }
 593         }
 594         for (uint j = 1; j < stop; j++) {
 595           if (n->in(j) != NULL && n->in(j)->bottom_type()->make_ptr() &&
 596               n->in(j)->bottom_type()->make_ptr()->make_oopptr()) {
 597             uint k = 0;
 598             for (; k < inputs_len && others[i].inputs[k].pos != (int)j; k++);
 599             if (k == inputs_len) {
 600               fatal("arg %d for node %s not covered", j, n->Name());
 601             }
 602           }
 603         }
 604       } else {
 605         for (uint j = 1; j < stop; j++) {
 606           if (n->in(j) != NULL && n->in(j)->bottom_type()->make_ptr() &&
 607               n->in(j)->bottom_type()->make_ptr()->make_oopptr()) {
 608             fatal("%s not covered", n->Name());
 609           }
 610         }
 611       }
 612     }
 613 
 614     if (n->is_SafePoint()) {
 615       SafePointNode* sfpt = n->as_SafePoint();
 616       if (verify_no_useless_barrier && sfpt->jvms() != NULL) {
 617         for (uint i = sfpt->jvms()->scloff(); i < sfpt->jvms()->endoff(); i++) {
 618           if (!verify_helper(sfpt->in(i), phis, visited, ShenandoahLoad, trace, barriers_used)) {
 619             phis.clear();
 620             visited.reset();
 621           }
 622         }
 623       }
 624     }
 625   }
 626 
 627   if (verify_no_useless_barrier) {
 628     for (int i = 0; i < barriers.length(); i++) {
 629       Node* n = barriers.at(i);
 630       if (!barriers_used.member(n)) {
 631         tty->print("XXX useless barrier"); n->dump(-2);
 632         ShouldNotReachHere();
 633       }
 634     }
 635   }
 636 }
 637 #endif
 638 
 639 bool ShenandoahBarrierC2Support::is_dominator_same_ctrl(Node* c, Node* d, Node* n, PhaseIdealLoop* phase) {
 640   // That both nodes have the same control is not sufficient to prove
 641   // domination, verify that there's no path from d to n
 642   ResourceMark rm;
 643   Unique_Node_List wq;
 644   wq.push(d);
 645   for (uint next = 0; next < wq.size(); next++) {
 646     Node *m = wq.at(next);
 647     if (m == n) {
 648       return false;
 649     }
 650     if (m->is_Phi() && m->in(0)->is_Loop()) {
 651       assert(phase->ctrl_or_self(m->in(LoopNode::EntryControl)) != c, "following loop entry should lead to new control");
 652     } else {
 653       if (m->is_Store() || m->is_LoadStore()) {
 654         // Take anti-dependencies into account
 655         Node* mem = m->in(MemNode::Memory);
 656         for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
 657           Node* u = mem->fast_out(i);
 658           if (u->is_Load() && phase->C->can_alias(m->adr_type(), phase->C->get_alias_index(u->adr_type())) &&
 659               phase->ctrl_or_self(u) == c) {
 660             wq.push(u);
 661           }
 662         }
 663       }
 664       for (uint i = 0; i < m->req(); i++) {
 665         if (m->in(i) != NULL && phase->ctrl_or_self(m->in(i)) == c) {
 666           wq.push(m->in(i));
 667         }
 668       }
 669     }
 670   }
 671   return true;
 672 }
 673 
 674 bool ShenandoahBarrierC2Support::is_dominator(Node* d_c, Node* n_c, Node* d, Node* n, PhaseIdealLoop* phase) {
 675   if (d_c != n_c) {
 676     return phase->is_dominator(d_c, n_c);
 677   }
 678   return is_dominator_same_ctrl(d_c, d, n, phase);
 679 }
 680 
 681 Node* next_mem(Node* mem, int alias) {
 682   Node* res = NULL;
 683   if (mem->is_Proj()) {
 684     res = mem->in(0);
 685   } else if (mem->is_SafePoint() || mem->is_MemBar()) {
 686     res = mem->in(TypeFunc::Memory);
 687   } else if (mem->is_Phi()) {
 688     res = mem->in(1);
 689   } else if (mem->is_MergeMem()) {
 690     res = mem->as_MergeMem()->memory_at(alias);
 691   } else if (mem->is_Store() || mem->is_LoadStore() || mem->is_ClearArray()) {
 692     assert(alias = Compile::AliasIdxRaw, "following raw memory can't lead to a barrier");
 693     res = mem->in(MemNode::Memory);
 694   } else {
 695 #ifdef ASSERT
 696     mem->dump();
 697 #endif
 698     ShouldNotReachHere();
 699   }
 700   return res;
 701 }
 702 
 703 Node* ShenandoahBarrierC2Support::no_branches(Node* c, Node* dom, bool allow_one_proj, PhaseIdealLoop* phase) {
 704   Node* iffproj = NULL;
 705   while (c != dom) {
 706     Node* next = phase->idom(c);
 707     assert(next->unique_ctrl_out() == c || c->is_Proj() || c->is_Region(), "multiple control flow out but no proj or region?");
 708     if (c->is_Region()) {
 709       ResourceMark rm;
 710       Unique_Node_List wq;
 711       wq.push(c);
 712       for (uint i = 0; i < wq.size(); i++) {
 713         Node *n = wq.at(i);
 714         if (n == next) {
 715           continue;
 716         }
 717         if (n->is_Region()) {
 718           for (uint j = 1; j < n->req(); j++) {
 719             wq.push(n->in(j));
 720           }
 721         } else {
 722           wq.push(n->in(0));
 723         }
 724       }
 725       for (uint i = 0; i < wq.size(); i++) {
 726         Node *n = wq.at(i);
 727         assert(n->is_CFG(), "");
 728         if (n->is_Multi()) {
 729           for (DUIterator_Fast jmax, j = n->fast_outs(jmax); j < jmax; j++) {
 730             Node* u = n->fast_out(j);
 731             if (u->is_CFG()) {
 732               if (!wq.member(u) && !u->as_Proj()->is_uncommon_trap_proj(Deoptimization::Reason_none)) {
 733                 return NodeSentinel;
 734               }
 735             }
 736           }
 737         }
 738       }
 739     } else  if (c->is_Proj()) {
 740       if (c->is_IfProj()) {
 741         if (c->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) != NULL) {
 742           // continue;
 743         } else {
 744           if (!allow_one_proj) {
 745             return NodeSentinel;
 746           }
 747           if (iffproj == NULL) {
 748             iffproj = c;
 749           } else {
 750             return NodeSentinel;
 751           }
 752         }
 753       } else if (c->Opcode() == Op_JumpProj) {
 754         return NodeSentinel; // unsupported
 755       } else if (c->Opcode() == Op_CatchProj) {
 756         return NodeSentinel; // unsupported
 757       } else if (c->Opcode() == Op_CProj && next->Opcode() == Op_NeverBranch) {
 758         return NodeSentinel; // unsupported
 759       } else {
 760         assert(next->unique_ctrl_out() == c, "unsupported branch pattern");
 761       }
 762     }
 763     c = next;
 764   }
 765   return iffproj;
 766 }
 767 
 768 Node* ShenandoahBarrierC2Support::dom_mem(Node* mem, Node* ctrl, int alias, Node*& mem_ctrl, PhaseIdealLoop* phase) {
 769   ResourceMark rm;
 770   VectorSet wq;
 771   wq.set(mem->_idx);
 772   mem_ctrl = phase->ctrl_or_self(mem);
 773   while (!phase->is_dominator(mem_ctrl, ctrl) || mem_ctrl == ctrl) {
 774     mem = next_mem(mem, alias);
 775     if (wq.test_set(mem->_idx)) {
 776       return NULL;
 777     }
 778     mem_ctrl = phase->ctrl_or_self(mem);
 779   }
 780   if (mem->is_MergeMem()) {
 781     mem = mem->as_MergeMem()->memory_at(alias);
 782     mem_ctrl = phase->ctrl_or_self(mem);
 783   }
 784   return mem;
 785 }
 786 
 787 Node* ShenandoahBarrierC2Support::find_bottom_mem(Node* ctrl, PhaseIdealLoop* phase) {
 788   Node* mem = NULL;
 789   Node* c = ctrl;
 790   do {
 791     if (c->is_Region()) {
 792       for (DUIterator_Fast imax, i = c->fast_outs(imax); i < imax && mem == NULL; i++) {
 793         Node* u = c->fast_out(i);
 794         if (u->is_Phi() && u->bottom_type() == Type::MEMORY) {
 795           if (u->adr_type() == TypePtr::BOTTOM) {
 796             mem = u;
 797           }
 798         }
 799       }
 800     } else {
 801       if (c->is_Call() && c->as_Call()->adr_type() != NULL) {
 802         CallProjections* projs = c->as_Call()->extract_projections(true, false);
 803         if (projs->fallthrough_memproj != NULL) {
 804           if (projs->fallthrough_memproj->adr_type() == TypePtr::BOTTOM) {
 805             if (projs->catchall_memproj == NULL) {
 806               mem = projs->fallthrough_memproj;
 807             } else {
 808               if (phase->is_dominator(projs->fallthrough_catchproj, ctrl)) {
 809                 mem = projs->fallthrough_memproj;
 810               } else {
 811                 assert(phase->is_dominator(projs->catchall_catchproj, ctrl), "one proj must dominate barrier");
 812                 mem = projs->catchall_memproj;
 813               }
 814             }
 815           }
 816         } else {
 817           Node* proj = c->as_Call()->proj_out(TypeFunc::Memory);
 818           if (proj != NULL &&
 819               proj->adr_type() == TypePtr::BOTTOM) {
 820             mem = proj;
 821           }
 822         }
 823       } else {
 824         for (DUIterator_Fast imax, i = c->fast_outs(imax); i < imax; i++) {
 825           Node* u = c->fast_out(i);
 826           if (u->is_Proj() &&
 827               u->bottom_type() == Type::MEMORY &&
 828               u->adr_type() == TypePtr::BOTTOM) {
 829               assert(c->is_SafePoint() || c->is_MemBar() || c->is_Start(), "");
 830               assert(mem == NULL, "only one proj");
 831               mem = u;
 832           }
 833         }
 834         assert(!c->is_Call() || c->as_Call()->adr_type() != NULL || mem == NULL, "no mem projection expected");
 835       }
 836     }
 837     c = phase->idom(c);
 838   } while (mem == NULL);
 839   return mem;
 840 }
 841 
 842 void ShenandoahBarrierC2Support::follow_barrier_uses(Node* n, Node* ctrl, Unique_Node_List& uses, PhaseIdealLoop* phase) {
 843   for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
 844     Node* u = n->fast_out(i);
 845     if (!u->is_CFG() && phase->get_ctrl(u) == ctrl && (!u->is_Phi() || !u->in(0)->is_Loop() || u->in(LoopNode::LoopBackControl) != n)) {
 846       uses.push(u);
 847     }
 848   }
 849 }
 850 
 851 static void hide_strip_mined_loop(OuterStripMinedLoopNode* outer, CountedLoopNode* inner, PhaseIdealLoop* phase) {
 852   OuterStripMinedLoopEndNode* le = inner->outer_loop_end();
 853   Node* new_outer = new LoopNode(outer->in(LoopNode::EntryControl), outer->in(LoopNode::LoopBackControl));
 854   phase->register_control(new_outer, phase->get_loop(outer), outer->in(LoopNode::EntryControl));
 855   Node* new_le = new IfNode(le->in(0), le->in(1), le->_prob, le->_fcnt);
 856   phase->register_control(new_le, phase->get_loop(le), le->in(0));
 857   phase->lazy_replace(outer, new_outer);
 858   phase->lazy_replace(le, new_le);
 859   inner->clear_strip_mined();
 860 }
 861 
 862 void ShenandoahBarrierC2Support::test_gc_state(Node*& ctrl, Node* raw_mem, Node*& test_fail_ctrl,
 863                                                PhaseIdealLoop* phase, int flags) {
 864   PhaseIterGVN& igvn = phase->igvn();
 865   Node* old_ctrl = ctrl;
 866 
 867   Node* thread          = new ThreadLocalNode();
 868   Node* gc_state_offset = igvn.MakeConX(in_bytes(ShenandoahThreadLocalData::gc_state_offset()));
 869   Node* gc_state_addr   = new AddPNode(phase->C->top(), thread, gc_state_offset);
 870   Node* gc_state        = new LoadBNode(old_ctrl, raw_mem, gc_state_addr,
 871                                         DEBUG_ONLY(phase->C->get_adr_type(Compile::AliasIdxRaw)) NOT_DEBUG(NULL),
 872                                         TypeInt::BYTE, MemNode::unordered);
 873   Node* gc_state_and    = new AndINode(gc_state, igvn.intcon(flags));
 874   Node* gc_state_cmp    = new CmpINode(gc_state_and, igvn.zerocon(T_INT));
 875   Node* gc_state_bool   = new BoolNode(gc_state_cmp, BoolTest::ne);
 876 
 877   IfNode* gc_state_iff  = new IfNode(old_ctrl, gc_state_bool, PROB_UNLIKELY(0.999), COUNT_UNKNOWN);
 878   ctrl                  = new IfTrueNode(gc_state_iff);
 879   test_fail_ctrl        = new IfFalseNode(gc_state_iff);
 880 
 881   IdealLoopTree* loop = phase->get_loop(old_ctrl);
 882   phase->register_control(gc_state_iff,   loop, old_ctrl);
 883   phase->register_control(ctrl,           loop, gc_state_iff);
 884   phase->register_control(test_fail_ctrl, loop, gc_state_iff);
 885 
 886   phase->register_new_node(thread,        old_ctrl);
 887   phase->register_new_node(gc_state_addr, old_ctrl);
 888   phase->register_new_node(gc_state,      old_ctrl);
 889   phase->register_new_node(gc_state_and,  old_ctrl);
 890   phase->register_new_node(gc_state_cmp,  old_ctrl);
 891   phase->register_new_node(gc_state_bool, old_ctrl);
 892 
 893   phase->set_ctrl(gc_state_offset, phase->C->root());
 894 
 895   assert(is_gc_state_test(gc_state_iff, flags), "Should match the shape");
 896 }
 897 
 898 void ShenandoahBarrierC2Support::test_null(Node*& ctrl, Node* val, Node*& null_ctrl, PhaseIdealLoop* phase) {
 899   Node* old_ctrl = ctrl;
 900   PhaseIterGVN& igvn = phase->igvn();
 901 
 902   const Type* val_t = igvn.type(val);
 903   if (val_t->meet(TypePtr::NULL_PTR) == val_t) {
 904     Node* null_cmp   = new CmpPNode(val, igvn.zerocon(T_OBJECT));
 905     Node* null_test  = new BoolNode(null_cmp, BoolTest::ne);
 906 
 907     IfNode* null_iff = new IfNode(old_ctrl, null_test, PROB_LIKELY(0.999), COUNT_UNKNOWN);
 908     ctrl             = new IfTrueNode(null_iff);
 909     null_ctrl        = new IfFalseNode(null_iff);
 910 
 911     IdealLoopTree* loop = phase->get_loop(old_ctrl);
 912     phase->register_control(null_iff,  loop, old_ctrl);
 913     phase->register_control(ctrl,      loop, null_iff);
 914     phase->register_control(null_ctrl, loop, null_iff);
 915 
 916     phase->register_new_node(null_cmp,  old_ctrl);
 917     phase->register_new_node(null_test, old_ctrl);
 918   }
 919 }
 920 
 921 void ShenandoahBarrierC2Support::test_in_cset(Node*& ctrl, Node*& not_cset_ctrl, Node* val, Node* raw_mem, PhaseIdealLoop* phase) {
 922   Node* old_ctrl = ctrl;
 923   PhaseIterGVN& igvn = phase->igvn();
 924 
 925   Node* raw_val        = new CastP2XNode(old_ctrl, val);
 926   Node* cset_idx       = new URShiftXNode(raw_val, igvn.intcon(ShenandoahHeapRegion::region_size_bytes_shift_jint()));
 927 
 928   // Figure out the target cset address with raw pointer math.
 929   // This avoids matching AddP+LoadB that would emit inefficient code.
 930   // See JDK-8245465.
 931   Node* cset_addr_ptr  = igvn.makecon(TypeRawPtr::make(ShenandoahHeap::in_cset_fast_test_addr()));
 932   Node* cset_addr      = new CastP2XNode(old_ctrl, cset_addr_ptr);
 933   Node* cset_load_addr = new AddXNode(cset_addr, cset_idx);
 934   Node* cset_load_ptr  = new CastX2PNode(cset_load_addr);
 935 
 936   Node* cset_load      = new LoadBNode(old_ctrl, raw_mem, cset_load_ptr,
 937                                        DEBUG_ONLY(phase->C->get_adr_type(Compile::AliasIdxRaw)) NOT_DEBUG(NULL),
 938                                        TypeInt::BYTE, MemNode::unordered);
 939   Node* cset_cmp       = new CmpINode(cset_load, igvn.zerocon(T_INT));
 940   Node* cset_bool      = new BoolNode(cset_cmp, BoolTest::ne);
 941 
 942   IfNode* cset_iff     = new IfNode(old_ctrl, cset_bool, PROB_UNLIKELY(0.999), COUNT_UNKNOWN);
 943   ctrl                 = new IfTrueNode(cset_iff);
 944   not_cset_ctrl        = new IfFalseNode(cset_iff);
 945 
 946   IdealLoopTree *loop = phase->get_loop(old_ctrl);
 947   phase->register_control(cset_iff,      loop, old_ctrl);
 948   phase->register_control(ctrl,          loop, cset_iff);
 949   phase->register_control(not_cset_ctrl, loop, cset_iff);
 950 
 951   phase->set_ctrl(cset_addr_ptr, phase->C->root());
 952 
 953   phase->register_new_node(raw_val,        old_ctrl);
 954   phase->register_new_node(cset_idx,       old_ctrl);
 955   phase->register_new_node(cset_addr,      old_ctrl);
 956   phase->register_new_node(cset_load_addr, old_ctrl);
 957   phase->register_new_node(cset_load_ptr,  old_ctrl);
 958   phase->register_new_node(cset_load,      old_ctrl);
 959   phase->register_new_node(cset_cmp,       old_ctrl);
 960   phase->register_new_node(cset_bool,      old_ctrl);
 961 }
 962 
 963 void ShenandoahBarrierC2Support::call_lrb_stub(Node*& ctrl, Node*& val, Node* load_addr, Node*& result_mem, Node* raw_mem, bool is_native, PhaseIdealLoop* phase) {
 964   IdealLoopTree*loop = phase->get_loop(ctrl);
 965   const TypePtr* obj_type = phase->igvn().type(val)->is_oopptr();
 966 
 967   // The slow path stub consumes and produces raw memory in addition
 968   // to the existing memory edges
 969   Node* base = find_bottom_mem(ctrl, phase);
 970   MergeMemNode* mm = MergeMemNode::make(base);
 971   mm->set_memory_at(Compile::AliasIdxRaw, raw_mem);
 972   phase->register_new_node(mm, ctrl);
 973 
 974   address target = LP64_ONLY(UseCompressedOops) NOT_LP64(false) ?
 975           CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_narrow) :
 976           CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier);
 977 
 978   address calladdr = is_native ? CAST_FROM_FN_PTR(address, ShenandoahRuntime::load_reference_barrier_native)
 979                                : target;
 980   const char* name = is_native ? "load_reference_barrier_native" : "load_reference_barrier";
 981   Node* call = new CallLeafNode(ShenandoahBarrierSetC2::shenandoah_load_reference_barrier_Type(), calladdr, name, TypeRawPtr::BOTTOM);
 982 
 983   call->init_req(TypeFunc::Control, ctrl);
 984   call->init_req(TypeFunc::I_O, phase->C->top());
 985   call->init_req(TypeFunc::Memory, mm);
 986   call->init_req(TypeFunc::FramePtr, phase->C->top());
 987   call->init_req(TypeFunc::ReturnAdr, phase->C->top());
 988   call->init_req(TypeFunc::Parms, val);
 989   call->init_req(TypeFunc::Parms+1, load_addr);
 990   phase->register_control(call, loop, ctrl);
 991   ctrl = new ProjNode(call, TypeFunc::Control);
 992   phase->register_control(ctrl, loop, call);
 993   result_mem = new ProjNode(call, TypeFunc::Memory);
 994   phase->register_new_node(result_mem, call);
 995   val = new ProjNode(call, TypeFunc::Parms);
 996   phase->register_new_node(val, call);
 997   val = new CheckCastPPNode(ctrl, val, obj_type);
 998   phase->register_new_node(val, ctrl);
 999 }
1000 
1001 void ShenandoahBarrierC2Support::fix_ctrl(Node* barrier, Node* region, const MemoryGraphFixer& fixer, Unique_Node_List& uses, Unique_Node_List& uses_to_ignore, uint last, PhaseIdealLoop* phase) {
1002   Node* ctrl = phase->get_ctrl(barrier);
1003   Node* init_raw_mem = fixer.find_mem(ctrl, barrier);
1004 
1005   // Update the control of all nodes that should be after the
1006   // barrier control flow
1007   uses.clear();
1008   // Every node that is control dependent on the barrier's input
1009   // control will be after the expanded barrier. The raw memory (if
1010   // its memory is control dependent on the barrier's input control)
1011   // must stay above the barrier.
1012   uses_to_ignore.clear();
1013   if (phase->has_ctrl(init_raw_mem) && phase->get_ctrl(init_raw_mem) == ctrl && !init_raw_mem->is_Phi()) {
1014     uses_to_ignore.push(init_raw_mem);
1015   }
1016   for (uint next = 0; next < uses_to_ignore.size(); next++) {
1017     Node *n = uses_to_ignore.at(next);
1018     for (uint i = 0; i < n->req(); i++) {
1019       Node* in = n->in(i);
1020       if (in != NULL && phase->has_ctrl(in) && phase->get_ctrl(in) == ctrl) {
1021         uses_to_ignore.push(in);
1022       }
1023     }
1024   }
1025   for (DUIterator_Fast imax, i = ctrl->fast_outs(imax); i < imax; i++) {
1026     Node* u = ctrl->fast_out(i);
1027     if (u->_idx < last &&
1028         u != barrier &&
1029         !uses_to_ignore.member(u) &&
1030         (u->in(0) != ctrl || (!u->is_Region() && !u->is_Phi())) &&
1031         (ctrl->Opcode() != Op_CatchProj || u->Opcode() != Op_CreateEx)) {
1032       Node* old_c = phase->ctrl_or_self(u);
1033       Node* c = old_c;
1034       if (c != ctrl ||
1035           is_dominator_same_ctrl(old_c, barrier, u, phase) ||
1036           ShenandoahBarrierSetC2::is_shenandoah_state_load(u)) {
1037         phase->igvn().rehash_node_delayed(u);
1038         int nb = u->replace_edge(ctrl, region);
1039         if (u->is_CFG()) {
1040           if (phase->idom(u) == ctrl) {
1041             phase->set_idom(u, region, phase->dom_depth(region));
1042           }
1043         } else if (phase->get_ctrl(u) == ctrl) {
1044           assert(u != init_raw_mem, "should leave input raw mem above the barrier");
1045           uses.push(u);
1046         }
1047         assert(nb == 1, "more than 1 ctrl input?");
1048         --i, imax -= nb;
1049       }
1050     }
1051   }
1052 }
1053 
1054 static Node* create_phis_on_call_return(Node* ctrl, Node* c, Node* n, Node* n_clone, const CallProjections* projs, PhaseIdealLoop* phase) {
1055   Node* region = NULL;
1056   while (c != ctrl) {
1057     if (c->is_Region()) {
1058       region = c;
1059     }
1060     c = phase->idom(c);
1061   }
1062   assert(region != NULL, "");
1063   Node* phi = new PhiNode(region, n->bottom_type());
1064   for (uint j = 1; j < region->req(); j++) {
1065     Node* in = region->in(j);
1066     if (phase->is_dominator(projs->fallthrough_catchproj, in)) {
1067       phi->init_req(j, n);
1068     } else if (phase->is_dominator(projs->catchall_catchproj, in)) {
1069       phi->init_req(j, n_clone);
1070     } else {
1071       phi->init_req(j, create_phis_on_call_return(ctrl, in, n, n_clone, projs, phase));
1072     }
1073   }
1074   phase->register_new_node(phi, region);
1075   return phi;
1076 }
1077 
1078 void ShenandoahBarrierC2Support::pin_and_expand(PhaseIdealLoop* phase) {
1079   ShenandoahBarrierSetC2State* state = ShenandoahBarrierSetC2::bsc2()->state();
1080 
1081   Unique_Node_List uses;
1082   for (int i = 0; i < state->enqueue_barriers_count(); i++) {
1083     Node* barrier = state->enqueue_barrier(i);
1084     Node* ctrl = phase->get_ctrl(barrier);
1085     IdealLoopTree* loop = phase->get_loop(ctrl);
1086     Node* head = loop->head();
1087     if (head->is_OuterStripMinedLoop()) {
1088       // Expanding a barrier here will break loop strip mining
1089       // verification. Transform the loop so the loop nest doesn't
1090       // appear as strip mined.
1091       OuterStripMinedLoopNode* outer = head->as_OuterStripMinedLoop();
1092       hide_strip_mined_loop(outer, outer->unique_ctrl_out()->as_CountedLoop(), phase);
1093     }
1094   }
1095 
1096   Node_Stack stack(0);
1097   Node_List clones;
1098   for (int i = state->load_reference_barriers_count() - 1; i >= 0; i--) {
1099     ShenandoahLoadReferenceBarrierNode* lrb = state->load_reference_barrier(i);
1100 
1101     Node* ctrl = phase->get_ctrl(lrb);
1102     Node* val = lrb->in(ShenandoahLoadReferenceBarrierNode::ValueIn);
1103 
1104     CallStaticJavaNode* unc = NULL;
1105     Node* unc_ctrl = NULL;
1106     Node* uncasted_val = val;
1107 
1108     for (DUIterator_Fast imax, i = lrb->fast_outs(imax); i < imax; i++) {
1109       Node* u = lrb->fast_out(i);
1110       if (u->Opcode() == Op_CastPP &&
1111           u->in(0) != NULL &&
1112           phase->is_dominator(u->in(0), ctrl)) {
1113         const Type* u_t = phase->igvn().type(u);
1114 
1115         if (u_t->meet(TypePtr::NULL_PTR) != u_t &&
1116             u->in(0)->Opcode() == Op_IfTrue &&
1117             u->in(0)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none) &&
1118             u->in(0)->in(0)->is_If() &&
1119             u->in(0)->in(0)->in(1)->Opcode() == Op_Bool &&
1120             u->in(0)->in(0)->in(1)->as_Bool()->_test._test == BoolTest::ne &&
1121             u->in(0)->in(0)->in(1)->in(1)->Opcode() == Op_CmpP &&
1122             u->in(0)->in(0)->in(1)->in(1)->in(1) == val &&
1123             u->in(0)->in(0)->in(1)->in(1)->in(2)->bottom_type() == TypePtr::NULL_PTR) {
1124           IdealLoopTree* loop = phase->get_loop(ctrl);
1125           IdealLoopTree* unc_loop = phase->get_loop(u->in(0));
1126 
1127           if (!unc_loop->is_member(loop)) {
1128             continue;
1129           }
1130 
1131           Node* branch = no_branches(ctrl, u->in(0), false, phase);
1132           assert(branch == NULL || branch == NodeSentinel, "was not looking for a branch");
1133           if (branch == NodeSentinel) {
1134             continue;
1135           }
1136 
1137           Node* iff = u->in(0)->in(0);
1138           Node* bol = iff->in(1)->clone();
1139           Node* cmp = bol->in(1)->clone();
1140           cmp->set_req(1, lrb);
1141           bol->set_req(1, cmp);
1142           phase->igvn().replace_input_of(iff, 1, bol);
1143           phase->set_ctrl(lrb, iff->in(0));
1144           phase->register_new_node(cmp, iff->in(0));
1145           phase->register_new_node(bol, iff->in(0));
1146           break;
1147         }
1148       }
1149     }
1150     if ((ctrl->is_Proj() && ctrl->in(0)->is_CallJava()) || ctrl->is_CallJava()) {
1151       CallNode* call = ctrl->is_Proj() ? ctrl->in(0)->as_CallJava() : ctrl->as_CallJava();
1152       if (call->entry_point() == OptoRuntime::rethrow_stub()) {
1153         // The rethrow call may have too many projections to be
1154         // properly handled here. Given there's no reason for a
1155         // barrier to depend on the call, move it above the call
1156         stack.push(lrb, 0);
1157         do {
1158           Node* n = stack.node();
1159           uint idx = stack.index();
1160           if (idx < n->req()) {
1161             Node* in = n->in(idx);
1162             stack.set_index(idx+1);
1163             if (in != NULL) {
1164               if (phase->has_ctrl(in)) {
1165                 if (phase->is_dominator(call, phase->get_ctrl(in))) {
1166 #ifdef ASSERT
1167                   for (uint i = 0; i < stack.size(); i++) {
1168                     assert(stack.node_at(i) != in, "node shouldn't have been seen yet");
1169                   }
1170 #endif
1171                   stack.push(in, 0);
1172                 }
1173               } else {
1174                 assert(phase->is_dominator(in, call->in(0)), "no dependency on the call");
1175               }
1176             }
1177           } else {
1178             phase->set_ctrl(n, call->in(0));
1179             stack.pop();
1180           }
1181         } while(stack.size() > 0);
1182         continue;
1183       }
1184       CallProjections* projs = call->extract_projections(false, false);
1185 #ifdef ASSERT
1186       VectorSet cloned;
1187 #endif
1188       Node* lrb_clone = lrb->clone();
1189       phase->register_new_node(lrb_clone, projs->catchall_catchproj);
1190       phase->set_ctrl(lrb, projs->fallthrough_catchproj);
1191 
1192       stack.push(lrb, 0);
1193       clones.push(lrb_clone);
1194 
1195       do {
1196         assert(stack.size() == clones.size(), "");
1197         Node* n = stack.node();
1198 #ifdef ASSERT
1199         if (n->is_Load()) {
1200           Node* mem = n->in(MemNode::Memory);
1201           for (DUIterator_Fast jmax, j = mem->fast_outs(jmax); j < jmax; j++) {
1202             Node* u = mem->fast_out(j);
1203             assert(!u->is_Store() || !u->is_LoadStore() || phase->get_ctrl(u) != ctrl, "anti dependent store?");
1204           }
1205         }
1206 #endif
1207         uint idx = stack.index();
1208         Node* n_clone = clones.at(clones.size()-1);
1209         if (idx < n->outcnt()) {
1210           Node* u = n->raw_out(idx);
1211           Node* c = phase->ctrl_or_self(u);
1212           if (phase->is_dominator(call, c) && phase->is_dominator(c, projs->fallthrough_proj)) {
1213             stack.set_index(idx+1);
1214             assert(!u->is_CFG(), "");
1215             stack.push(u, 0);
1216             assert(!cloned.test_set(u->_idx), "only one clone");
1217             Node* u_clone = u->clone();
1218             int nb = u_clone->replace_edge(n, n_clone);
1219             assert(nb > 0, "should have replaced some uses");
1220             phase->register_new_node(u_clone, projs->catchall_catchproj);
1221             clones.push(u_clone);
1222             phase->set_ctrl(u, projs->fallthrough_catchproj);
1223           } else {
1224             bool replaced = false;
1225             if (u->is_Phi()) {
1226               for (uint k = 1; k < u->req(); k++) {
1227                 if (u->in(k) == n) {
1228                   if (phase->is_dominator(projs->catchall_catchproj, u->in(0)->in(k))) {
1229                     phase->igvn().replace_input_of(u, k, n_clone);
1230                     replaced = true;
1231                   } else if (!phase->is_dominator(projs->fallthrough_catchproj, u->in(0)->in(k))) {
1232                     phase->igvn().replace_input_of(u, k, create_phis_on_call_return(ctrl, u->in(0)->in(k), n, n_clone, projs, phase));
1233                     replaced = true;
1234                   }
1235                 }
1236               }
1237             } else {
1238               if (phase->is_dominator(projs->catchall_catchproj, c)) {
1239                 phase->igvn().rehash_node_delayed(u);
1240                 int nb = u->replace_edge(n, n_clone);
1241                 assert(nb > 0, "should have replaced some uses");
1242                 replaced = true;
1243               } else if (!phase->is_dominator(projs->fallthrough_catchproj, c)) {
1244                 if (u->is_If()) {
1245                   // Can't break If/Bool/Cmp chain
1246                   assert(n->is_Bool(), "unexpected If shape");
1247                   assert(stack.node_at(stack.size()-2)->is_Cmp(), "unexpected If shape");
1248                   assert(n_clone->is_Bool(), "unexpected clone");
1249                   assert(clones.at(clones.size()-2)->is_Cmp(), "unexpected clone");
1250                   Node* bol_clone = n->clone();
1251                   Node* cmp_clone = stack.node_at(stack.size()-2)->clone();
1252                   bol_clone->set_req(1, cmp_clone);
1253 
1254                   Node* nn = stack.node_at(stack.size()-3);
1255                   Node* nn_clone = clones.at(clones.size()-3);
1256                   assert(nn->Opcode() == nn_clone->Opcode(), "mismatch");
1257 
1258                   int nb = cmp_clone->replace_edge(nn, create_phis_on_call_return(ctrl, c, nn, nn_clone, projs, phase));
1259                   assert(nb > 0, "should have replaced some uses");
1260 
1261                   phase->register_new_node(bol_clone, u->in(0));
1262                   phase->register_new_node(cmp_clone, u->in(0));
1263 
1264                   phase->igvn().replace_input_of(u, 1, bol_clone);
1265 
1266                 } else {
1267                   phase->igvn().rehash_node_delayed(u);
1268                   int nb = u->replace_edge(n, create_phis_on_call_return(ctrl, c, n, n_clone, projs, phase));
1269                   assert(nb > 0, "should have replaced some uses");
1270                 }
1271                 replaced = true;
1272               }
1273             }
1274             if (!replaced) {
1275               stack.set_index(idx+1);
1276             }
1277           }
1278         } else {
1279           stack.pop();
1280           clones.pop();
1281         }
1282       } while (stack.size() > 0);
1283       assert(stack.size() == 0 && clones.size() == 0, "");
1284     }
1285   }
1286 
1287   for (int i = 0; i < state->load_reference_barriers_count(); i++) {
1288     ShenandoahLoadReferenceBarrierNode* lrb = state->load_reference_barrier(i);
1289     Node* ctrl = phase->get_ctrl(lrb);
1290     IdealLoopTree* loop = phase->get_loop(ctrl);
1291     Node* head = loop->head();
1292     if (head->is_OuterStripMinedLoop()) {
1293       // Expanding a barrier here will break loop strip mining
1294       // verification. Transform the loop so the loop nest doesn't
1295       // appear as strip mined.
1296       OuterStripMinedLoopNode* outer = head->as_OuterStripMinedLoop();
1297       hide_strip_mined_loop(outer, outer->unique_ctrl_out()->as_CountedLoop(), phase);
1298     }
1299   }
1300 
1301   // Expand load-reference-barriers
1302   MemoryGraphFixer fixer(Compile::AliasIdxRaw, true, phase);
1303   Unique_Node_List uses_to_ignore;
1304   for (int i = state->load_reference_barriers_count() - 1; i >= 0; i--) {
1305     ShenandoahLoadReferenceBarrierNode* lrb = state->load_reference_barrier(i);
1306     uint last = phase->C->unique();
1307     Node* ctrl = phase->get_ctrl(lrb);
1308     Node* val = lrb->in(ShenandoahLoadReferenceBarrierNode::ValueIn);
1309 
1310 
1311     Node* orig_ctrl = ctrl;
1312 
1313     Node* raw_mem = fixer.find_mem(ctrl, lrb);
1314     Node* init_raw_mem = raw_mem;
1315     Node* raw_mem_for_ctrl = fixer.find_mem(ctrl, NULL);
1316 
1317     IdealLoopTree *loop = phase->get_loop(ctrl);
1318 
1319     Node* heap_stable_ctrl = NULL;
1320     Node* null_ctrl = NULL;
1321 
1322     assert(val->bottom_type()->make_oopptr(), "need oop");
1323     assert(val->bottom_type()->make_oopptr()->const_oop() == NULL, "expect non-constant");
1324 
1325     enum { _heap_stable = 1, _not_cset, _evac_path, PATH_LIMIT };
1326     Node* region = new RegionNode(PATH_LIMIT);
1327     Node* val_phi = new PhiNode(region, val->bottom_type()->is_oopptr());
1328     Node* raw_mem_phi = PhiNode::make(region, raw_mem, Type::MEMORY, TypeRawPtr::BOTTOM);
1329 
1330     // Stable path.
1331     test_gc_state(ctrl, raw_mem, heap_stable_ctrl, phase, ShenandoahHeap::HAS_FORWARDED);
1332     IfNode* heap_stable_iff = heap_stable_ctrl->in(0)->as_If();
1333 
1334     // Heap stable case
1335     region->init_req(_heap_stable, heap_stable_ctrl);
1336     val_phi->init_req(_heap_stable, val);
1337     raw_mem_phi->init_req(_heap_stable, raw_mem);
1338 
1339     // Test for in-cset.
1340     // Wires !in_cset(obj) to slot 2 of region and phis
1341     Node* not_cset_ctrl = NULL;
1342     test_in_cset(ctrl, not_cset_ctrl, val, raw_mem, phase);
1343     if (not_cset_ctrl != NULL) {
1344       region->init_req(_not_cset, not_cset_ctrl);
1345       val_phi->init_req(_not_cset, val);
1346       raw_mem_phi->init_req(_not_cset, raw_mem);
1347     }
1348 
1349     // Resolve object when orig-value is in cset.
1350     // Make the unconditional resolve for fwdptr.
1351 
1352     // Call lrb-stub and wire up that path in slots 4
1353     Node* result_mem = NULL;
1354 
1355     Node* addr;
1356     if (ShenandoahSelfFixing) {
1357       VectorSet visited;
1358       addr = get_load_addr(phase, visited, lrb);
1359     } else {
1360       addr = phase->igvn().zerocon(T_OBJECT);
1361     }
1362     if (addr->Opcode() == Op_AddP) {
1363       Node* orig_base = addr->in(AddPNode::Base);
1364       Node* base = new CheckCastPPNode(ctrl, orig_base, orig_base->bottom_type(), true);
1365       phase->register_new_node(base, ctrl);
1366       if (addr->in(AddPNode::Base) == addr->in((AddPNode::Address))) {
1367         // Field access
1368         addr = addr->clone();
1369         addr->set_req(AddPNode::Base, base);
1370         addr->set_req(AddPNode::Address, base);
1371         phase->register_new_node(addr, ctrl);
1372       } else {
1373         Node* addr2 = addr->in(AddPNode::Address);
1374         if (addr2->Opcode() == Op_AddP && addr2->in(AddPNode::Base) == addr2->in(AddPNode::Address) &&
1375               addr2->in(AddPNode::Base) == orig_base) {
1376           addr2 = addr2->clone();
1377           addr2->set_req(AddPNode::Base, base);
1378           addr2->set_req(AddPNode::Address, base);
1379           phase->register_new_node(addr2, ctrl);
1380           addr = addr->clone();
1381           addr->set_req(AddPNode::Base, base);
1382           addr->set_req(AddPNode::Address, addr2);
1383           phase->register_new_node(addr, ctrl);
1384         }
1385       }
1386     }
1387     call_lrb_stub(ctrl, val, addr, result_mem, raw_mem, lrb->is_native(), phase);
1388     region->init_req(_evac_path, ctrl);
1389     val_phi->init_req(_evac_path, val);
1390     raw_mem_phi->init_req(_evac_path, result_mem);
1391 
1392     phase->register_control(region, loop, heap_stable_iff);
1393     Node* out_val = val_phi;
1394     phase->register_new_node(val_phi, region);
1395     phase->register_new_node(raw_mem_phi, region);
1396 
1397     fix_ctrl(lrb, region, fixer, uses, uses_to_ignore, last, phase);
1398 
1399     ctrl = orig_ctrl;
1400 
1401     phase->igvn().replace_node(lrb, out_val);
1402 
1403     follow_barrier_uses(out_val, ctrl, uses, phase);
1404 
1405     for(uint next = 0; next < uses.size(); next++ ) {
1406       Node *n = uses.at(next);
1407       assert(phase->get_ctrl(n) == ctrl, "bad control");
1408       assert(n != init_raw_mem, "should leave input raw mem above the barrier");
1409       phase->set_ctrl(n, region);
1410       follow_barrier_uses(n, ctrl, uses, phase);
1411     }
1412 
1413     // The slow path call produces memory: hook the raw memory phi
1414     // from the expanded load reference barrier with the rest of the graph
1415     // which may require adding memory phis at every post dominated
1416     // region and at enclosing loop heads. Use the memory state
1417     // collected in memory_nodes to fix the memory graph. Update that
1418     // memory state as we go.
1419     fixer.fix_mem(ctrl, region, init_raw_mem, raw_mem_for_ctrl, raw_mem_phi, uses);
1420   }
1421   // Done expanding load-reference-barriers.
1422   assert(ShenandoahBarrierSetC2::bsc2()->state()->load_reference_barriers_count() == 0, "all load reference barrier nodes should have been replaced");
1423 
1424   for (int i = state->enqueue_barriers_count() - 1; i >= 0; i--) {
1425     Node* barrier = state->enqueue_barrier(i);
1426     Node* pre_val = barrier->in(1);
1427 
1428     if (phase->igvn().type(pre_val)->higher_equal(TypePtr::NULL_PTR)) {
1429       ShouldNotReachHere();
1430       continue;
1431     }
1432 
1433     Node* ctrl = phase->get_ctrl(barrier);
1434 
1435     if (ctrl->is_Proj() && ctrl->in(0)->is_CallJava()) {
1436       assert(is_dominator(phase->get_ctrl(pre_val), ctrl->in(0)->in(0), pre_val, ctrl->in(0), phase), "can't move");
1437       ctrl = ctrl->in(0)->in(0);
1438       phase->set_ctrl(barrier, ctrl);
1439     } else if (ctrl->is_CallRuntime()) {
1440       assert(is_dominator(phase->get_ctrl(pre_val), ctrl->in(0), pre_val, ctrl, phase), "can't move");
1441       ctrl = ctrl->in(0);
1442       phase->set_ctrl(barrier, ctrl);
1443     }
1444 
1445     Node* init_ctrl = ctrl;
1446     IdealLoopTree* loop = phase->get_loop(ctrl);
1447     Node* raw_mem = fixer.find_mem(ctrl, barrier);
1448     Node* init_raw_mem = raw_mem;
1449     Node* raw_mem_for_ctrl = fixer.find_mem(ctrl, NULL);
1450     Node* heap_stable_ctrl = NULL;
1451     Node* null_ctrl = NULL;
1452     uint last = phase->C->unique();
1453 
1454     enum { _heap_stable = 1, _heap_unstable, PATH_LIMIT };
1455     Node* region = new RegionNode(PATH_LIMIT);
1456     Node* phi = PhiNode::make(region, raw_mem, Type::MEMORY, TypeRawPtr::BOTTOM);
1457 
1458     enum { _fast_path = 1, _slow_path, _null_path, PATH_LIMIT2 };
1459     Node* region2 = new RegionNode(PATH_LIMIT2);
1460     Node* phi2 = PhiNode::make(region2, raw_mem, Type::MEMORY, TypeRawPtr::BOTTOM);
1461 
1462     // Stable path.
1463     test_gc_state(ctrl, raw_mem, heap_stable_ctrl, phase, ShenandoahHeap::MARKING);
1464     region->init_req(_heap_stable, heap_stable_ctrl);
1465     phi->init_req(_heap_stable, raw_mem);
1466 
1467     // Null path
1468     Node* reg2_ctrl = NULL;
1469     test_null(ctrl, pre_val, null_ctrl, phase);
1470     if (null_ctrl != NULL) {
1471       reg2_ctrl = null_ctrl->in(0);
1472       region2->init_req(_null_path, null_ctrl);
1473       phi2->init_req(_null_path, raw_mem);
1474     } else {
1475       region2->del_req(_null_path);
1476       phi2->del_req(_null_path);
1477     }
1478 
1479     const int index_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset());
1480     const int buffer_offset = in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset());
1481     Node* thread = new ThreadLocalNode();
1482     phase->register_new_node(thread, ctrl);
1483     Node* buffer_adr = new AddPNode(phase->C->top(), thread, phase->igvn().MakeConX(buffer_offset));
1484     phase->register_new_node(buffer_adr, ctrl);
1485     Node* index_adr = new AddPNode(phase->C->top(), thread, phase->igvn().MakeConX(index_offset));
1486     phase->register_new_node(index_adr, ctrl);
1487 
1488     BasicType index_bt = TypeX_X->basic_type();
1489     assert(sizeof(size_t) == type2aelembytes(index_bt), "Loading G1 SATBMarkQueue::_index with wrong size.");
1490     const TypePtr* adr_type = TypeRawPtr::BOTTOM;
1491     Node* index = new LoadXNode(ctrl, raw_mem, index_adr, adr_type, TypeX_X, MemNode::unordered);
1492     phase->register_new_node(index, ctrl);
1493     Node* index_cmp = new CmpXNode(index, phase->igvn().MakeConX(0));
1494     phase->register_new_node(index_cmp, ctrl);
1495     Node* index_test = new BoolNode(index_cmp, BoolTest::ne);
1496     phase->register_new_node(index_test, ctrl);
1497     IfNode* queue_full_iff = new IfNode(ctrl, index_test, PROB_LIKELY(0.999), COUNT_UNKNOWN);
1498     if (reg2_ctrl == NULL) reg2_ctrl = queue_full_iff;
1499     phase->register_control(queue_full_iff, loop, ctrl);
1500     Node* not_full = new IfTrueNode(queue_full_iff);
1501     phase->register_control(not_full, loop, queue_full_iff);
1502     Node* full = new IfFalseNode(queue_full_iff);
1503     phase->register_control(full, loop, queue_full_iff);
1504 
1505     ctrl = not_full;
1506 
1507     Node* next_index = new SubXNode(index, phase->igvn().MakeConX(sizeof(intptr_t)));
1508     phase->register_new_node(next_index, ctrl);
1509 
1510     Node* buffer  = new LoadPNode(ctrl, raw_mem, buffer_adr, adr_type, TypeRawPtr::NOTNULL, MemNode::unordered);
1511     phase->register_new_node(buffer, ctrl);
1512     Node *log_addr = new AddPNode(phase->C->top(), buffer, next_index);
1513     phase->register_new_node(log_addr, ctrl);
1514     Node* log_store = new StorePNode(ctrl, raw_mem, log_addr, adr_type, pre_val, MemNode::unordered);
1515     phase->register_new_node(log_store, ctrl);
1516     // update the index
1517     Node* index_update = new StoreXNode(ctrl, log_store, index_adr, adr_type, next_index, MemNode::unordered);
1518     phase->register_new_node(index_update, ctrl);
1519 
1520     // Fast-path case
1521     region2->init_req(_fast_path, ctrl);
1522     phi2->init_req(_fast_path, index_update);
1523 
1524     ctrl = full;
1525 
1526     Node* base = find_bottom_mem(ctrl, phase);
1527 
1528     MergeMemNode* mm = MergeMemNode::make(base);
1529     mm->set_memory_at(Compile::AliasIdxRaw, raw_mem);
1530     phase->register_new_node(mm, ctrl);
1531 
1532     Node* call = new CallLeafNode(ShenandoahBarrierSetC2::write_ref_field_pre_entry_Type(), CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), "shenandoah_wb_pre", TypeRawPtr::BOTTOM);
1533     call->init_req(TypeFunc::Control, ctrl);
1534     call->init_req(TypeFunc::I_O, phase->C->top());
1535     call->init_req(TypeFunc::Memory, mm);
1536     call->init_req(TypeFunc::FramePtr, phase->C->top());
1537     call->init_req(TypeFunc::ReturnAdr, phase->C->top());
1538     call->init_req(TypeFunc::Parms, pre_val);
1539     call->init_req(TypeFunc::Parms+1, thread);
1540     phase->register_control(call, loop, ctrl);
1541 
1542     Node* ctrl_proj = new ProjNode(call, TypeFunc::Control);
1543     phase->register_control(ctrl_proj, loop, call);
1544     Node* mem_proj = new ProjNode(call, TypeFunc::Memory);
1545     phase->register_new_node(mem_proj, call);
1546 
1547     // Slow-path case
1548     region2->init_req(_slow_path, ctrl_proj);
1549     phi2->init_req(_slow_path, mem_proj);
1550 
1551     phase->register_control(region2, loop, reg2_ctrl);
1552     phase->register_new_node(phi2, region2);
1553 
1554     region->init_req(_heap_unstable, region2);
1555     phi->init_req(_heap_unstable, phi2);
1556 
1557     phase->register_control(region, loop, heap_stable_ctrl->in(0));
1558     phase->register_new_node(phi, region);
1559 
1560     fix_ctrl(barrier, region, fixer, uses, uses_to_ignore, last, phase);
1561     for(uint next = 0; next < uses.size(); next++ ) {
1562       Node *n = uses.at(next);
1563       assert(phase->get_ctrl(n) == init_ctrl, "bad control");
1564       assert(n != init_raw_mem, "should leave input raw mem above the barrier");
1565       phase->set_ctrl(n, region);
1566       follow_barrier_uses(n, init_ctrl, uses, phase);
1567     }
1568     fixer.fix_mem(init_ctrl, region, init_raw_mem, raw_mem_for_ctrl, phi, uses);
1569 
1570     phase->igvn().replace_node(barrier, pre_val);
1571   }
1572   assert(state->enqueue_barriers_count() == 0, "all enqueue barrier nodes should have been replaced");
1573 
1574 }
1575 
1576 Node* ShenandoahBarrierC2Support::get_load_addr(PhaseIdealLoop* phase, VectorSet& visited, Node* in) {
1577   if (visited.test_set(in->_idx)) {
1578     return NULL;
1579   }
1580   switch (in->Opcode()) {
1581     case Op_Proj:
1582       return get_load_addr(phase, visited, in->in(0));
1583     case Op_CastPP:
1584     case Op_CheckCastPP:
1585     case Op_DecodeN:
1586     case Op_EncodeP:
1587       return get_load_addr(phase, visited, in->in(1));
1588     case Op_LoadN:
1589     case Op_LoadP:
1590       return in->in(MemNode::Address);
1591     case Op_CompareAndExchangeN:
1592     case Op_CompareAndExchangeP:
1593     case Op_GetAndSetN:
1594     case Op_GetAndSetP:
1595     case Op_ShenandoahCompareAndExchangeP:
1596     case Op_ShenandoahCompareAndExchangeN:
1597       // Those instructions would just have stored a different
1598       // value into the field. No use to attempt to fix it at this point.
1599       return phase->igvn().zerocon(T_OBJECT);
1600     case Op_CMoveP:
1601     case Op_CMoveN: {
1602       Node* t = get_load_addr(phase, visited, in->in(CMoveNode::IfTrue));
1603       Node* f = get_load_addr(phase, visited, in->in(CMoveNode::IfFalse));
1604       // Handle unambiguous cases: single address reported on both branches.
1605       if (t != NULL && f == NULL) return t;
1606       if (t == NULL && f != NULL) return f;
1607       if (t != NULL && t == f)    return t;
1608       // Ambiguity.
1609       return phase->igvn().zerocon(T_OBJECT);
1610     }
1611     case Op_Phi: {
1612       Node* addr = NULL;
1613       for (uint i = 1; i < in->req(); i++) {
1614         Node* addr1 = get_load_addr(phase, visited, in->in(i));
1615         if (addr == NULL) {
1616           addr = addr1;
1617         }
1618         if (addr != addr1) {
1619           return phase->igvn().zerocon(T_OBJECT);
1620         }
1621       }
1622       return addr;
1623     }
1624     case Op_ShenandoahLoadReferenceBarrier:
1625       return get_load_addr(phase, visited, in->in(ShenandoahLoadReferenceBarrierNode::ValueIn));
1626     case Op_ShenandoahEnqueueBarrier:
1627       return get_load_addr(phase, visited, in->in(1));
1628     case Op_CallDynamicJava:
1629     case Op_CallLeaf:
1630     case Op_CallStaticJava:
1631     case Op_ConN:
1632     case Op_ConP:
1633     case Op_Parm:
1634     case Op_CreateEx:
1635       return phase->igvn().zerocon(T_OBJECT);
1636     default:
1637 #ifdef ASSERT
1638       fatal("Unknown node in get_load_addr: %s", NodeClassNames[in->Opcode()]);
1639 #endif
1640       return phase->igvn().zerocon(T_OBJECT);
1641   }
1642 
1643 }
1644 
1645 void ShenandoahBarrierC2Support::move_gc_state_test_out_of_loop(IfNode* iff, PhaseIdealLoop* phase) {
1646   IdealLoopTree *loop = phase->get_loop(iff);
1647   Node* loop_head = loop->_head;
1648   Node* entry_c = loop_head->in(LoopNode::EntryControl);
1649 
1650   Node* bol = iff->in(1);
1651   Node* cmp = bol->in(1);
1652   Node* andi = cmp->in(1);
1653   Node* load = andi->in(1);
1654 
1655   assert(is_gc_state_load(load), "broken");
1656   if (!phase->is_dominator(load->in(0), entry_c)) {
1657     Node* mem_ctrl = NULL;
1658     Node* mem = dom_mem(load->in(MemNode::Memory), loop_head, Compile::AliasIdxRaw, mem_ctrl, phase);
1659     load = load->clone();
1660     load->set_req(MemNode::Memory, mem);
1661     load->set_req(0, entry_c);
1662     phase->register_new_node(load, entry_c);
1663     andi = andi->clone();
1664     andi->set_req(1, load);
1665     phase->register_new_node(andi, entry_c);
1666     cmp = cmp->clone();
1667     cmp->set_req(1, andi);
1668     phase->register_new_node(cmp, entry_c);
1669     bol = bol->clone();
1670     bol->set_req(1, cmp);
1671     phase->register_new_node(bol, entry_c);
1672 
1673     phase->igvn().replace_input_of(iff, 1, bol);
1674   }
1675 }
1676 
1677 bool ShenandoahBarrierC2Support::identical_backtoback_ifs(Node* n, PhaseIdealLoop* phase) {
1678   if (!n->is_If() || n->is_CountedLoopEnd()) {
1679     return false;
1680   }
1681   Node* region = n->in(0);
1682 
1683   if (!region->is_Region()) {
1684     return false;
1685   }
1686   Node* dom = phase->idom(region);
1687   if (!dom->is_If()) {
1688     return false;
1689   }
1690 
1691   if (!is_heap_stable_test(n) || !is_heap_stable_test(dom)) {
1692     return false;
1693   }
1694 
1695   IfNode* dom_if = dom->as_If();
1696   Node* proj_true = dom_if->proj_out(1);
1697   Node* proj_false = dom_if->proj_out(0);
1698 
1699   for (uint i = 1; i < region->req(); i++) {
1700     if (phase->is_dominator(proj_true, region->in(i))) {
1701       continue;
1702     }
1703     if (phase->is_dominator(proj_false, region->in(i))) {
1704       continue;
1705     }
1706     return false;
1707   }
1708 
1709   return true;
1710 }
1711 
1712 void ShenandoahBarrierC2Support::merge_back_to_back_tests(Node* n, PhaseIdealLoop* phase) {
1713   assert(is_heap_stable_test(n), "no other tests");
1714   if (identical_backtoback_ifs(n, phase)) {
1715     Node* n_ctrl = n->in(0);
1716     if (phase->can_split_if(n_ctrl)) {
1717       IfNode* dom_if = phase->idom(n_ctrl)->as_If();
1718       if (is_heap_stable_test(n)) {
1719         Node* gc_state_load = n->in(1)->in(1)->in(1)->in(1);
1720         assert(is_gc_state_load(gc_state_load), "broken");
1721         Node* dom_gc_state_load = dom_if->in(1)->in(1)->in(1)->in(1);
1722         assert(is_gc_state_load(dom_gc_state_load), "broken");
1723         if (gc_state_load != dom_gc_state_load) {
1724           phase->igvn().replace_node(gc_state_load, dom_gc_state_load);
1725         }
1726       }
1727       PhiNode* bolphi = PhiNode::make_blank(n_ctrl, n->in(1));
1728       Node* proj_true = dom_if->proj_out(1);
1729       Node* proj_false = dom_if->proj_out(0);
1730       Node* con_true = phase->igvn().makecon(TypeInt::ONE);
1731       Node* con_false = phase->igvn().makecon(TypeInt::ZERO);
1732 
1733       for (uint i = 1; i < n_ctrl->req(); i++) {
1734         if (phase->is_dominator(proj_true, n_ctrl->in(i))) {
1735           bolphi->init_req(i, con_true);
1736         } else {
1737           assert(phase->is_dominator(proj_false, n_ctrl->in(i)), "bad if");
1738           bolphi->init_req(i, con_false);
1739         }
1740       }
1741       phase->register_new_node(bolphi, n_ctrl);
1742       phase->igvn().replace_input_of(n, 1, bolphi);
1743       phase->do_split_if(n);
1744     }
1745   }
1746 }
1747 
1748 IfNode* ShenandoahBarrierC2Support::find_unswitching_candidate(const IdealLoopTree* loop, PhaseIdealLoop* phase) {
1749   // Find first invariant test that doesn't exit the loop
1750   LoopNode *head = loop->_head->as_Loop();
1751   IfNode* unswitch_iff = NULL;
1752   Node* n = head->in(LoopNode::LoopBackControl);
1753   int loop_has_sfpts = -1;
1754   while (n != head) {
1755     Node* n_dom = phase->idom(n);
1756     if (n->is_Region()) {
1757       if (n_dom->is_If()) {
1758         IfNode* iff = n_dom->as_If();
1759         if (iff->in(1)->is_Bool()) {
1760           BoolNode* bol = iff->in(1)->as_Bool();
1761           if (bol->in(1)->is_Cmp()) {
1762             // If condition is invariant and not a loop exit,
1763             // then found reason to unswitch.
1764             if (is_heap_stable_test(iff) &&
1765                 (loop_has_sfpts == -1 || loop_has_sfpts == 0)) {
1766               assert(!loop->is_loop_exit(iff), "both branches should be in the loop");
1767               if (loop_has_sfpts == -1) {
1768                 for(uint i = 0; i < loop->_body.size(); i++) {
1769                   Node *m = loop->_body[i];
1770                   if (m->is_SafePoint() && !m->is_CallLeaf()) {
1771                     loop_has_sfpts = 1;
1772                     break;
1773                   }
1774                 }
1775                 if (loop_has_sfpts == -1) {
1776                   loop_has_sfpts = 0;
1777                 }
1778               }
1779               if (!loop_has_sfpts) {
1780                 unswitch_iff = iff;
1781               }
1782             }
1783           }
1784         }
1785       }
1786     }
1787     n = n_dom;
1788   }
1789   return unswitch_iff;
1790 }
1791 
1792 
1793 void ShenandoahBarrierC2Support::optimize_after_expansion(VectorSet &visited, Node_Stack &stack, Node_List &old_new, PhaseIdealLoop* phase) {
1794   Node_List heap_stable_tests;
1795   stack.push(phase->C->start(), 0);
1796   do {
1797     Node* n = stack.node();
1798     uint i = stack.index();
1799 
1800     if (i < n->outcnt()) {
1801       Node* u = n->raw_out(i);
1802       stack.set_index(i+1);
1803       if (!visited.test_set(u->_idx)) {
1804         stack.push(u, 0);
1805       }
1806     } else {
1807       stack.pop();
1808       if (n->is_If() && is_heap_stable_test(n)) {
1809         heap_stable_tests.push(n);
1810       }
1811     }
1812   } while (stack.size() > 0);
1813 
1814   for (uint i = 0; i < heap_stable_tests.size(); i++) {
1815     Node* n = heap_stable_tests.at(i);
1816     assert(is_heap_stable_test(n), "only evacuation test");
1817     merge_back_to_back_tests(n, phase);
1818   }
1819 
1820   if (!phase->C->major_progress()) {
1821     VectorSet seen;
1822     for (uint i = 0; i < heap_stable_tests.size(); i++) {
1823       Node* n = heap_stable_tests.at(i);
1824       IdealLoopTree* loop = phase->get_loop(n);
1825       if (loop != phase->ltree_root() &&
1826           loop->_child == NULL &&
1827           !loop->_irreducible) {
1828         Node* head = loop->_head;
1829         if (head->is_Loop() &&
1830             (!head->is_CountedLoop() || head->as_CountedLoop()->is_main_loop() || head->as_CountedLoop()->is_normal_loop()) &&
1831             !seen.test_set(head->_idx)) {
1832           IfNode* iff = find_unswitching_candidate(loop, phase);
1833           if (iff != NULL) {
1834             Node* bol = iff->in(1);
1835             if (head->as_Loop()->is_strip_mined()) {
1836               head->as_Loop()->verify_strip_mined(0);
1837             }
1838             move_gc_state_test_out_of_loop(iff, phase);
1839 
1840             AutoNodeBudget node_budget(phase);
1841 
1842             if (loop->policy_unswitching(phase)) {
1843               if (head->as_Loop()->is_strip_mined()) {
1844                 OuterStripMinedLoopNode* outer = head->as_CountedLoop()->outer_loop();
1845                 hide_strip_mined_loop(outer, head->as_CountedLoop(), phase);
1846               }
1847               phase->do_unswitching(loop, old_new);
1848             } else {
1849               // Not proceeding with unswitching. Move load back in
1850               // the loop.
1851               phase->igvn().replace_input_of(iff, 1, bol);
1852             }
1853           }
1854         }
1855       }
1856     }
1857   }
1858 }
1859 
1860 #ifdef ASSERT
1861 void ShenandoahBarrierC2Support::verify_raw_mem(RootNode* root) {
1862   const bool trace = false;
1863   ResourceMark rm;
1864   Unique_Node_List nodes;
1865   Unique_Node_List controls;
1866   Unique_Node_List memories;
1867 
1868   nodes.push(root);
1869   for (uint next = 0; next < nodes.size(); next++) {
1870     Node *n  = nodes.at(next);
1871     if (ShenandoahBarrierSetC2::is_shenandoah_lrb_call(n)) {
1872       controls.push(n);
1873       if (trace) { tty->print("XXXXXX verifying"); n->dump(); }
1874       for (uint next2 = 0; next2 < controls.size(); next2++) {
1875         Node *m = controls.at(next2);
1876         for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
1877           Node* u = m->fast_out(i);
1878           if (u->is_CFG() && !u->is_Root() &&
1879               !(u->Opcode() == Op_CProj && u->in(0)->Opcode() == Op_NeverBranch && u->as_Proj()->_con == 1) &&
1880               !(u->is_Region() && u->unique_ctrl_out()->Opcode() == Op_Halt)) {
1881             if (trace) { tty->print("XXXXXX pushing control"); u->dump(); }
1882             controls.push(u);
1883           }
1884         }
1885       }
1886       memories.push(n->as_Call()->proj_out(TypeFunc::Memory));
1887       for (uint next2 = 0; next2 < memories.size(); next2++) {
1888         Node *m = memories.at(next2);
1889         assert(m->bottom_type() == Type::MEMORY, "");
1890         for (DUIterator_Fast imax, i = m->fast_outs(imax); i < imax; i++) {
1891           Node* u = m->fast_out(i);
1892           if (u->bottom_type() == Type::MEMORY && (u->is_Mem() || u->is_ClearArray())) {
1893             if (trace) { tty->print("XXXXXX pushing memory"); u->dump(); }
1894             memories.push(u);
1895           } else if (u->is_LoadStore()) {
1896             if (trace) { tty->print("XXXXXX pushing memory"); u->find_out_with(Op_SCMemProj)->dump(); }
1897             memories.push(u->find_out_with(Op_SCMemProj));
1898           } else if (u->is_MergeMem() && u->as_MergeMem()->memory_at(Compile::AliasIdxRaw) == m) {
1899             if (trace) { tty->print("XXXXXX pushing memory"); u->dump(); }
1900             memories.push(u);
1901           } else if (u->is_Phi()) {
1902             assert(u->bottom_type() == Type::MEMORY, "");
1903             if (u->adr_type() == TypeRawPtr::BOTTOM || u->adr_type() == TypePtr::BOTTOM) {
1904               assert(controls.member(u->in(0)), "");
1905               if (trace) { tty->print("XXXXXX pushing memory"); u->dump(); }
1906               memories.push(u);
1907             }
1908           } else if (u->is_SafePoint() || u->is_MemBar()) {
1909             for (DUIterator_Fast jmax, j = u->fast_outs(jmax); j < jmax; j++) {
1910               Node* uu = u->fast_out(j);
1911               if (uu->bottom_type() == Type::MEMORY) {
1912                 if (trace) { tty->print("XXXXXX pushing memory"); uu->dump(); }
1913                 memories.push(uu);
1914               }
1915             }
1916           }
1917         }
1918       }
1919       for (uint next2 = 0; next2 < controls.size(); next2++) {
1920         Node *m = controls.at(next2);
1921         if (m->is_Region()) {
1922           bool all_in = true;
1923           for (uint i = 1; i < m->req(); i++) {
1924             if (!controls.member(m->in(i))) {
1925               all_in = false;
1926               break;
1927             }
1928           }
1929           if (trace) { tty->print("XXX verifying %s", all_in ? "all in" : ""); m->dump(); }
1930           bool found_phi = false;
1931           for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax && !found_phi; j++) {
1932             Node* u = m->fast_out(j);
1933             if (u->is_Phi() && memories.member(u)) {
1934               found_phi = true;
1935               for (uint i = 1; i < u->req() && found_phi; i++) {
1936                 Node* k = u->in(i);
1937                 if (memories.member(k) != controls.member(m->in(i))) {
1938                   found_phi = false;
1939                 }
1940               }
1941             }
1942           }
1943           assert(found_phi || all_in, "");
1944         }
1945       }
1946       controls.clear();
1947       memories.clear();
1948     }
1949     for( uint i = 0; i < n->len(); ++i ) {
1950       Node *m = n->in(i);
1951       if (m != NULL) {
1952         nodes.push(m);
1953       }
1954     }
1955   }
1956 }
1957 #endif
1958 
1959 ShenandoahEnqueueBarrierNode::ShenandoahEnqueueBarrierNode(Node* val) : Node(NULL, val) {
1960   ShenandoahBarrierSetC2::bsc2()->state()->add_enqueue_barrier(this);
1961 }
1962 
1963 const Type* ShenandoahEnqueueBarrierNode::bottom_type() const {
1964   if (in(1) == NULL || in(1)->is_top()) {
1965     return Type::TOP;
1966   }
1967   const Type* t = in(1)->bottom_type();
1968   if (t == TypePtr::NULL_PTR) {
1969     return t;
1970   }
1971   return t->is_oopptr();
1972 }
1973 
1974 const Type* ShenandoahEnqueueBarrierNode::Value(PhaseGVN* phase) const {
1975   if (in(1) == NULL) {
1976     return Type::TOP;
1977   }
1978   const Type* t = phase->type(in(1));
1979   if (t == Type::TOP) {
1980     return Type::TOP;
1981   }
1982   if (t == TypePtr::NULL_PTR) {
1983     return t;
1984   }
1985   return t->is_oopptr();
1986 }
1987 
1988 int ShenandoahEnqueueBarrierNode::needed(Node* n) {
1989   if (n == NULL ||
1990       n->is_Allocate() ||
1991       n->Opcode() == Op_ShenandoahEnqueueBarrier ||
1992       n->bottom_type() == TypePtr::NULL_PTR ||
1993       (n->bottom_type()->make_oopptr() != NULL && n->bottom_type()->make_oopptr()->const_oop() != NULL)) {
1994     return NotNeeded;
1995   }
1996   if (n->is_Phi() ||
1997       n->is_CMove()) {
1998     return MaybeNeeded;
1999   }
2000   return Needed;
2001 }
2002 
2003 Node* ShenandoahEnqueueBarrierNode::next(Node* n) {
2004   for (;;) {
2005     if (n == NULL) {
2006       return n;
2007     } else if (n->bottom_type() == TypePtr::NULL_PTR) {
2008       return n;
2009     } else if (n->bottom_type()->make_oopptr() != NULL && n->bottom_type()->make_oopptr()->const_oop() != NULL) {
2010       return n;
2011     } else if (n->is_ConstraintCast() ||
2012                n->Opcode() == Op_DecodeN ||
2013                n->Opcode() == Op_EncodeP) {
2014       n = n->in(1);
2015     } else if (n->is_Proj()) {
2016       n = n->in(0);
2017     } else {
2018       return n;
2019     }
2020   }
2021   ShouldNotReachHere();
2022   return NULL;
2023 }
2024 
2025 Node* ShenandoahEnqueueBarrierNode::Identity(PhaseGVN* phase) {
2026   PhaseIterGVN* igvn = phase->is_IterGVN();
2027 
2028   Node* n = next(in(1));
2029 
2030   int cont = needed(n);
2031 
2032   if (cont == NotNeeded) {
2033     return in(1);
2034   } else if (cont == MaybeNeeded) {
2035     if (igvn == NULL) {
2036       phase->record_for_igvn(this);
2037       return this;
2038     } else {
2039       ResourceMark rm;
2040       Unique_Node_List wq;
2041       uint wq_i = 0;
2042 
2043       for (;;) {
2044         if (n->is_Phi()) {
2045           for (uint i = 1; i < n->req(); i++) {
2046             Node* m = n->in(i);
2047             if (m != NULL) {
2048               wq.push(m);
2049             }
2050           }
2051         } else {
2052           assert(n->is_CMove(), "nothing else here");
2053           Node* m = n->in(CMoveNode::IfFalse);
2054           wq.push(m);
2055           m = n->in(CMoveNode::IfTrue);
2056           wq.push(m);
2057         }
2058         Node* orig_n = NULL;
2059         do {
2060           if (wq_i >= wq.size()) {
2061             return in(1);
2062           }
2063           n = wq.at(wq_i);
2064           wq_i++;
2065           orig_n = n;
2066           n = next(n);
2067           cont = needed(n);
2068           if (cont == Needed) {
2069             return this;
2070           }
2071         } while (cont != MaybeNeeded || (orig_n != n && wq.member(n)));
2072       }
2073     }
2074   }
2075 
2076   return this;
2077 }
2078 
2079 #ifdef ASSERT
2080 static bool has_never_branch(Node* root) {
2081   for (uint i = 1; i < root->req(); i++) {
2082     Node* in = root->in(i);
2083     if (in != NULL && in->Opcode() == Op_Halt && in->in(0)->is_Proj() && in->in(0)->in(0)->Opcode() == Op_NeverBranch) {
2084       return true;
2085     }
2086   }
2087   return false;
2088 }
2089 #endif
2090 
2091 void MemoryGraphFixer::collect_memory_nodes() {
2092   Node_Stack stack(0);
2093   VectorSet visited;
2094   Node_List regions;
2095 
2096   // Walk the raw memory graph and create a mapping from CFG node to
2097   // memory node. Exclude phis for now.
2098   stack.push(_phase->C->root(), 1);
2099   do {
2100     Node* n = stack.node();
2101     int opc = n->Opcode();
2102     uint i = stack.index();
2103     if (i < n->req()) {
2104       Node* mem = NULL;
2105       if (opc == Op_Root) {
2106         Node* in = n->in(i);
2107         int in_opc = in->Opcode();
2108         if (in_opc == Op_Return || in_opc == Op_Rethrow) {
2109           mem = in->in(TypeFunc::Memory);
2110         } else if (in_opc == Op_Halt) {
2111           if (in->in(0)->is_Region()) {
2112             Node* r = in->in(0);
2113             for (uint j = 1; j < r->req(); j++) {
2114               assert(r->in(j)->Opcode() != Op_NeverBranch, "");
2115             }
2116           } else {
2117             Node* proj = in->in(0);
2118             assert(proj->is_Proj(), "");
2119             Node* in = proj->in(0);
2120             assert(in->is_CallStaticJava() || in->Opcode() == Op_NeverBranch || in->Opcode() == Op_Catch || proj->is_IfProj(), "");
2121             if (in->is_CallStaticJava()) {
2122               mem = in->in(TypeFunc::Memory);
2123             } else if (in->Opcode() == Op_Catch) {
2124               Node* call = in->in(0)->in(0);
2125               assert(call->is_Call(), "");
2126               mem = call->in(TypeFunc::Memory);
2127             } else if (in->Opcode() == Op_NeverBranch) {
2128               Node* head = in->in(0);
2129               assert(head->is_Region(), "unexpected infinite loop graph shape");
2130 
2131               Node* phi_mem = NULL;
2132               for (DUIterator_Fast jmax, j = head->fast_outs(jmax); j < jmax; j++) {
2133                 Node* u = head->fast_out(j);
2134                 if (u->is_Phi() && u->bottom_type() == Type::MEMORY) {
2135                   if (_phase->C->get_alias_index(u->adr_type()) == _alias) {
2136                     assert(phi_mem == NULL || phi_mem->adr_type() == TypePtr::BOTTOM, "");
2137                     phi_mem = u;
2138                   } else if (u->adr_type() == TypePtr::BOTTOM) {
2139                     assert(phi_mem == NULL || _phase->C->get_alias_index(phi_mem->adr_type()) == _alias, "");
2140                     if (phi_mem == NULL) {
2141                       phi_mem = u;
2142                     }
2143                   }
2144                 }
2145               }
2146               if (phi_mem == NULL) {
2147                 for (uint j = 1; j < head->req(); j++) {
2148                   Node* tail = head->in(j);
2149                   if (!_phase->is_dominator(head, tail)) {
2150                     continue;
2151                   }
2152                   Node* c = tail;
2153                   while (c != head) {
2154                     if (c->is_SafePoint() && !c->is_CallLeaf()) {
2155                       Node* m =c->in(TypeFunc::Memory);
2156                       if (m->is_MergeMem()) {
2157                         m = m->as_MergeMem()->memory_at(_alias);
2158                       }
2159                       assert(mem == NULL || mem == m, "several memory states");
2160                       mem = m;
2161                     }
2162                     c = _phase->idom(c);
2163                   }
2164                   assert(mem != NULL, "should have found safepoint");
2165                 }
2166                 assert(mem != NULL, "should have found safepoint");
2167               } else {
2168                 mem = phi_mem;
2169               }
2170             }
2171           }
2172         } else {
2173 #ifdef ASSERT
2174           n->dump();
2175           in->dump();
2176 #endif
2177           ShouldNotReachHere();
2178         }
2179       } else {
2180         assert(n->is_Phi() && n->bottom_type() == Type::MEMORY, "");
2181         assert(n->adr_type() == TypePtr::BOTTOM || _phase->C->get_alias_index(n->adr_type()) == _alias, "");
2182         mem = n->in(i);
2183       }
2184       i++;
2185       stack.set_index(i);
2186       if (mem == NULL) {
2187         continue;
2188       }
2189       for (;;) {
2190         if (visited.test_set(mem->_idx) || mem->is_Start()) {
2191           break;
2192         }
2193         if (mem->is_Phi()) {
2194           stack.push(mem, 2);
2195           mem = mem->in(1);
2196         } else if (mem->is_Proj()) {
2197           stack.push(mem, mem->req());
2198           mem = mem->in(0);
2199         } else if (mem->is_SafePoint() || mem->is_MemBar()) {
2200           mem = mem->in(TypeFunc::Memory);
2201         } else if (mem->is_MergeMem()) {
2202           MergeMemNode* mm = mem->as_MergeMem();
2203           mem = mm->memory_at(_alias);
2204         } else if (mem->is_Store() || mem->is_LoadStore() || mem->is_ClearArray()) {
2205           assert(_alias == Compile::AliasIdxRaw, "");
2206           stack.push(mem, mem->req());
2207           mem = mem->in(MemNode::Memory);
2208         } else {
2209 #ifdef ASSERT
2210           mem->dump();
2211 #endif
2212           ShouldNotReachHere();
2213         }
2214       }
2215     } else {
2216       if (n->is_Phi()) {
2217         // Nothing
2218       } else if (!n->is_Root()) {
2219         Node* c = get_ctrl(n);
2220         _memory_nodes.map(c->_idx, n);
2221       }
2222       stack.pop();
2223     }
2224   } while(stack.is_nonempty());
2225 
2226   // Iterate over CFG nodes in rpo and propagate memory state to
2227   // compute memory state at regions, creating new phis if needed.
2228   Node_List rpo_list;
2229   visited.clear();
2230   _phase->rpo(_phase->C->root(), stack, visited, rpo_list);
2231   Node* root = rpo_list.pop();
2232   assert(root == _phase->C->root(), "");
2233 
2234   const bool trace = false;
2235 #ifdef ASSERT
2236   if (trace) {
2237     for (int i = rpo_list.size() - 1; i >= 0; i--) {
2238       Node* c = rpo_list.at(i);
2239       if (_memory_nodes[c->_idx] != NULL) {
2240         tty->print("X %d", c->_idx);  _memory_nodes[c->_idx]->dump();
2241       }
2242     }
2243   }
2244 #endif
2245   uint last = _phase->C->unique();
2246 
2247 #ifdef ASSERT
2248   uint8_t max_depth = 0;
2249   for (LoopTreeIterator iter(_phase->ltree_root()); !iter.done(); iter.next()) {
2250     IdealLoopTree* lpt = iter.current();
2251     max_depth = MAX2(max_depth, lpt->_nest);
2252   }
2253 #endif
2254 
2255   bool progress = true;
2256   int iteration = 0;
2257   Node_List dead_phis;
2258   while (progress) {
2259     progress = false;
2260     iteration++;
2261     assert(iteration <= 2+max_depth || _phase->C->has_irreducible_loop() || has_never_branch(_phase->C->root()), "");
2262     if (trace) { tty->print_cr("XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"); }
2263 
2264     for (int i = rpo_list.size() - 1; i >= 0; i--) {
2265       Node* c = rpo_list.at(i);
2266 
2267       Node* prev_mem = _memory_nodes[c->_idx];
2268       if (c->is_Region() && (_include_lsm || !c->is_OuterStripMinedLoop())) {
2269         Node* prev_region = regions[c->_idx];
2270         Node* unique = NULL;
2271         for (uint j = 1; j < c->req() && unique != NodeSentinel; j++) {
2272           Node* m = _memory_nodes[c->in(j)->_idx];
2273           assert(m != NULL || (c->is_Loop() && j == LoopNode::LoopBackControl && iteration == 1) || _phase->C->has_irreducible_loop() || has_never_branch(_phase->C->root()), "expect memory state");
2274           if (m != NULL) {
2275             if (m == prev_region && ((c->is_Loop() && j == LoopNode::LoopBackControl) || (prev_region->is_Phi() && prev_region->in(0) == c))) {
2276               assert(c->is_Loop() && j == LoopNode::LoopBackControl || _phase->C->has_irreducible_loop() || has_never_branch(_phase->C->root()), "");
2277               // continue
2278             } else if (unique == NULL) {
2279               unique = m;
2280             } else if (m == unique) {
2281               // continue
2282             } else {
2283               unique = NodeSentinel;
2284             }
2285           }
2286         }
2287         assert(unique != NULL, "empty phi???");
2288         if (unique != NodeSentinel) {
2289           if (prev_region != NULL && prev_region->is_Phi() && prev_region->in(0) == c) {
2290             dead_phis.push(prev_region);
2291           }
2292           regions.map(c->_idx, unique);
2293         } else {
2294           Node* phi = NULL;
2295           if (prev_region != NULL && prev_region->is_Phi() && prev_region->in(0) == c && prev_region->_idx >= last) {
2296             phi = prev_region;
2297             for (uint k = 1; k < c->req(); k++) {
2298               Node* m = _memory_nodes[c->in(k)->_idx];
2299               assert(m != NULL, "expect memory state");
2300               phi->set_req(k, m);
2301             }
2302           } else {
2303             for (DUIterator_Fast jmax, j = c->fast_outs(jmax); j < jmax && phi == NULL; j++) {
2304               Node* u = c->fast_out(j);
2305               if (u->is_Phi() && u->bottom_type() == Type::MEMORY &&
2306                   (u->adr_type() == TypePtr::BOTTOM || _phase->C->get_alias_index(u->adr_type()) == _alias)) {
2307                 phi = u;
2308                 for (uint k = 1; k < c->req() && phi != NULL; k++) {
2309                   Node* m = _memory_nodes[c->in(k)->_idx];
2310                   assert(m != NULL, "expect memory state");
2311                   if (u->in(k) != m) {
2312                     phi = NULL;
2313                   }
2314                 }
2315               }
2316             }
2317             if (phi == NULL) {
2318               phi = new PhiNode(c, Type::MEMORY, _phase->C->get_adr_type(_alias));
2319               for (uint k = 1; k < c->req(); k++) {
2320                 Node* m = _memory_nodes[c->in(k)->_idx];
2321                 assert(m != NULL, "expect memory state");
2322                 phi->init_req(k, m);
2323               }
2324             }
2325           }
2326           assert(phi != NULL, "");
2327           regions.map(c->_idx, phi);
2328         }
2329         Node* current_region = regions[c->_idx];
2330         if (current_region != prev_region) {
2331           progress = true;
2332           if (prev_region == prev_mem) {
2333             _memory_nodes.map(c->_idx, current_region);
2334           }
2335         }
2336       } else if (prev_mem == NULL || prev_mem->is_Phi() || ctrl_or_self(prev_mem) != c) {
2337         Node* m = _memory_nodes[_phase->idom(c)->_idx];
2338         assert(m != NULL, "expect memory state");
2339         if (m != prev_mem) {
2340           _memory_nodes.map(c->_idx, m);
2341           progress = true;
2342         }
2343       }
2344 #ifdef ASSERT
2345       if (trace) { tty->print("X %d", c->_idx);  _memory_nodes[c->_idx]->dump(); }
2346 #endif
2347     }
2348   }
2349 
2350   // Replace existing phi with computed memory state for that region
2351   // if different (could be a new phi or a dominating memory node if
2352   // that phi was found to be useless).
2353   while (dead_phis.size() > 0) {
2354     Node* n = dead_phis.pop();
2355     n->replace_by(_phase->C->top());
2356     n->destruct();
2357   }
2358   for (int i = rpo_list.size() - 1; i >= 0; i--) {
2359     Node* c = rpo_list.at(i);
2360     if (c->is_Region() && (_include_lsm || !c->is_OuterStripMinedLoop())) {
2361       Node* n = regions[c->_idx];
2362       if (n->is_Phi() && n->_idx >= last && n->in(0) == c) {
2363         _phase->register_new_node(n, c);
2364       }
2365     }
2366   }
2367   for (int i = rpo_list.size() - 1; i >= 0; i--) {
2368     Node* c = rpo_list.at(i);
2369     if (c->is_Region() && (_include_lsm || !c->is_OuterStripMinedLoop())) {
2370       Node* n = regions[c->_idx];
2371       for (DUIterator_Fast imax, i = c->fast_outs(imax); i < imax; i++) {
2372         Node* u = c->fast_out(i);
2373         if (u->is_Phi() && u->bottom_type() == Type::MEMORY &&
2374             u != n) {
2375           if (u->adr_type() == TypePtr::BOTTOM) {
2376             fix_memory_uses(u, n, n, c);
2377           } else if (_phase->C->get_alias_index(u->adr_type()) == _alias) {
2378             _phase->lazy_replace(u, n);
2379             --i; --imax;
2380           }
2381         }
2382       }
2383     }
2384   }
2385 }
2386 
2387 Node* MemoryGraphFixer::get_ctrl(Node* n) const {
2388   Node* c = _phase->get_ctrl(n);
2389   if (n->is_Proj() && n->in(0) != NULL && n->in(0)->is_Call()) {
2390     assert(c == n->in(0), "");
2391     CallNode* call = c->as_Call();
2392     CallProjections* projs = call->extract_projections(true, false);
2393     if (projs->catchall_memproj != NULL) {
2394       if (projs->fallthrough_memproj == n) {
2395         c = projs->fallthrough_catchproj;
2396       } else {
2397         assert(projs->catchall_memproj == n, "");
2398         c = projs->catchall_catchproj;
2399       }
2400     }
2401   }
2402   return c;
2403 }
2404 
2405 Node* MemoryGraphFixer::ctrl_or_self(Node* n) const {
2406   if (_phase->has_ctrl(n))
2407     return get_ctrl(n);
2408   else {
2409     assert (n->is_CFG(), "must be a CFG node");
2410     return n;
2411   }
2412 }
2413 
2414 bool MemoryGraphFixer::mem_is_valid(Node* m, Node* c) const {
2415   return m != NULL && get_ctrl(m) == c;
2416 }
2417 
2418 Node* MemoryGraphFixer::find_mem(Node* ctrl, Node* n) const {
2419   assert(n == NULL || _phase->ctrl_or_self(n) == ctrl, "");
2420   Node* mem = _memory_nodes[ctrl->_idx];
2421   Node* c = ctrl;
2422   while (!mem_is_valid(mem, c) &&
2423          (!c->is_CatchProj() || mem == NULL || c->in(0)->in(0)->in(0) != get_ctrl(mem))) {
2424     c = _phase->idom(c);
2425     mem = _memory_nodes[c->_idx];
2426   }
2427   if (n != NULL && mem_is_valid(mem, c)) {
2428     while (!ShenandoahBarrierC2Support::is_dominator_same_ctrl(c, mem, n, _phase) && _phase->ctrl_or_self(mem) == ctrl) {
2429       mem = next_mem(mem, _alias);
2430     }
2431     if (mem->is_MergeMem()) {
2432       mem = mem->as_MergeMem()->memory_at(_alias);
2433     }
2434     if (!mem_is_valid(mem, c)) {
2435       do {
2436         c = _phase->idom(c);
2437         mem = _memory_nodes[c->_idx];
2438       } while (!mem_is_valid(mem, c) &&
2439                (!c->is_CatchProj() || mem == NULL || c->in(0)->in(0)->in(0) != get_ctrl(mem)));
2440     }
2441   }
2442   assert(mem->bottom_type() == Type::MEMORY, "");
2443   return mem;
2444 }
2445 
2446 bool MemoryGraphFixer::has_mem_phi(Node* region) const {
2447   for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
2448     Node* use = region->fast_out(i);
2449     if (use->is_Phi() && use->bottom_type() == Type::MEMORY &&
2450         (_phase->C->get_alias_index(use->adr_type()) == _alias)) {
2451       return true;
2452     }
2453   }
2454   return false;
2455 }
2456 
2457 void MemoryGraphFixer::fix_mem(Node* ctrl, Node* new_ctrl, Node* mem, Node* mem_for_ctrl, Node* new_mem, Unique_Node_List& uses) {
2458   assert(_phase->ctrl_or_self(new_mem) == new_ctrl, "");
2459   const bool trace = false;
2460   DEBUG_ONLY(if (trace) { tty->print("ZZZ control is"); ctrl->dump(); });
2461   DEBUG_ONLY(if (trace) { tty->print("ZZZ mem is"); mem->dump(); });
2462   GrowableArray<Node*> phis;
2463   if (mem_for_ctrl != mem) {
2464     Node* old = mem_for_ctrl;
2465     Node* prev = NULL;
2466     while (old != mem) {
2467       prev = old;
2468       if (old->is_Store() || old->is_ClearArray() || old->is_LoadStore()) {
2469         assert(_alias == Compile::AliasIdxRaw, "");
2470         old = old->in(MemNode::Memory);
2471       } else if (old->Opcode() == Op_SCMemProj) {
2472         assert(_alias == Compile::AliasIdxRaw, "");
2473         old = old->in(0);
2474       } else {
2475         ShouldNotReachHere();
2476       }
2477     }
2478     assert(prev != NULL, "");
2479     if (new_ctrl != ctrl) {
2480       _memory_nodes.map(ctrl->_idx, mem);
2481       _memory_nodes.map(new_ctrl->_idx, mem_for_ctrl);
2482     }
2483     uint input = (uint)MemNode::Memory;
2484     _phase->igvn().replace_input_of(prev, input, new_mem);
2485   } else {
2486     uses.clear();
2487     _memory_nodes.map(new_ctrl->_idx, new_mem);
2488     uses.push(new_ctrl);
2489     for(uint next = 0; next < uses.size(); next++ ) {
2490       Node *n = uses.at(next);
2491       assert(n->is_CFG(), "");
2492       DEBUG_ONLY(if (trace) { tty->print("ZZZ ctrl"); n->dump(); });
2493       for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
2494         Node* u = n->fast_out(i);
2495         if (!u->is_Root() && u->is_CFG() && u != n) {
2496           Node* m = _memory_nodes[u->_idx];
2497           if (u->is_Region() && (!u->is_OuterStripMinedLoop() || _include_lsm) &&
2498               !has_mem_phi(u) &&
2499               u->unique_ctrl_out()->Opcode() != Op_Halt) {
2500             DEBUG_ONLY(if (trace) { tty->print("ZZZ region"); u->dump(); });
2501             DEBUG_ONLY(if (trace && m != NULL) { tty->print("ZZZ mem"); m->dump(); });
2502 
2503             if (!mem_is_valid(m, u) || !m->is_Phi()) {
2504               bool push = true;
2505               bool create_phi = true;
2506               if (_phase->is_dominator(new_ctrl, u)) {
2507                 create_phi = false;
2508               }
2509               if (create_phi) {
2510                 Node* phi = new PhiNode(u, Type::MEMORY, _phase->C->get_adr_type(_alias));
2511                 _phase->register_new_node(phi, u);
2512                 phis.push(phi);
2513                 DEBUG_ONLY(if (trace) { tty->print("ZZZ new phi"); phi->dump(); });
2514                 if (!mem_is_valid(m, u)) {
2515                   DEBUG_ONLY(if (trace) { tty->print("ZZZ setting mem"); phi->dump(); });
2516                   _memory_nodes.map(u->_idx, phi);
2517                 } else {
2518                   DEBUG_ONLY(if (trace) { tty->print("ZZZ NOT setting mem"); m->dump(); });
2519                   for (;;) {
2520                     assert(m->is_Mem() || m->is_LoadStore() || m->is_Proj(), "");
2521                     Node* next = NULL;
2522                     if (m->is_Proj()) {
2523                       next = m->in(0);
2524                     } else {
2525                       assert(m->is_Mem() || m->is_LoadStore(), "");
2526                       assert(_alias == Compile::AliasIdxRaw, "");
2527                       next = m->in(MemNode::Memory);
2528                     }
2529                     if (_phase->get_ctrl(next) != u) {
2530                       break;
2531                     }
2532                     if (next->is_MergeMem()) {
2533                       assert(_phase->get_ctrl(next->as_MergeMem()->memory_at(_alias)) != u, "");
2534                       break;
2535                     }
2536                     if (next->is_Phi()) {
2537                       assert(next->adr_type() == TypePtr::BOTTOM && next->in(0) == u, "");
2538                       break;
2539                     }
2540                     m = next;
2541                   }
2542 
2543                   DEBUG_ONLY(if (trace) { tty->print("ZZZ setting to phi"); m->dump(); });
2544                   assert(m->is_Mem() || m->is_LoadStore(), "");
2545                   uint input = (uint)MemNode::Memory;
2546                   _phase->igvn().replace_input_of(m, input, phi);
2547                   push = false;
2548                 }
2549               } else {
2550                 DEBUG_ONLY(if (trace) { tty->print("ZZZ skipping region"); u->dump(); });
2551               }
2552               if (push) {
2553                 uses.push(u);
2554               }
2555             }
2556           } else if (!mem_is_valid(m, u) &&
2557                      !(u->Opcode() == Op_CProj && u->in(0)->Opcode() == Op_NeverBranch && u->as_Proj()->_con == 1)) {
2558             uses.push(u);
2559           }
2560         }
2561       }
2562     }
2563     for (int i = 0; i < phis.length(); i++) {
2564       Node* n = phis.at(i);
2565       Node* r = n->in(0);
2566       DEBUG_ONLY(if (trace) { tty->print("ZZZ fixing new phi"); n->dump(); });
2567       for (uint j = 1; j < n->req(); j++) {
2568         Node* m = find_mem(r->in(j), NULL);
2569         _phase->igvn().replace_input_of(n, j, m);
2570         DEBUG_ONLY(if (trace) { tty->print("ZZZ fixing new phi: %d", j); m->dump(); });
2571       }
2572     }
2573   }
2574   uint last = _phase->C->unique();
2575   MergeMemNode* mm = NULL;
2576   int alias = _alias;
2577   DEBUG_ONLY(if (trace) { tty->print("ZZZ raw mem is"); mem->dump(); });
2578   // Process loads first to not miss an anti-dependency: if the memory
2579   // edge of a store is updated before a load is processed then an
2580   // anti-dependency may be missed.
2581   for (DUIterator i = mem->outs(); mem->has_out(i); i++) {
2582     Node* u = mem->out(i);
2583     if (u->_idx < last && u->is_Load() && _phase->C->get_alias_index(u->adr_type()) == alias) {
2584       Node* m = find_mem(_phase->get_ctrl(u), u);
2585       if (m != mem) {
2586         DEBUG_ONLY(if (trace) { tty->print("ZZZ setting memory of use"); u->dump(); });
2587         _phase->igvn().replace_input_of(u, MemNode::Memory, m);
2588         --i;
2589       }
2590     }
2591   }
2592   for (DUIterator i = mem->outs(); mem->has_out(i); i++) {
2593     Node* u = mem->out(i);
2594     if (u->_idx < last) {
2595       if (u->is_Mem()) {
2596         if (_phase->C->get_alias_index(u->adr_type()) == alias) {
2597           Node* m = find_mem(_phase->get_ctrl(u), u);
2598           if (m != mem) {
2599             DEBUG_ONLY(if (trace) { tty->print("ZZZ setting memory of use"); u->dump(); });
2600             _phase->igvn().replace_input_of(u, MemNode::Memory, m);
2601             --i;
2602           }
2603         }
2604       } else if (u->is_MergeMem()) {
2605         MergeMemNode* u_mm = u->as_MergeMem();
2606         if (u_mm->memory_at(alias) == mem) {
2607           MergeMemNode* newmm = NULL;
2608           for (DUIterator_Fast jmax, j = u->fast_outs(jmax); j < jmax; j++) {
2609             Node* uu = u->fast_out(j);
2610             assert(!uu->is_MergeMem(), "chain of MergeMems?");
2611             if (uu->is_Phi()) {
2612               assert(uu->adr_type() == TypePtr::BOTTOM, "");
2613               Node* region = uu->in(0);
2614               int nb = 0;
2615               for (uint k = 1; k < uu->req(); k++) {
2616                 if (uu->in(k) == u) {
2617                   Node* m = find_mem(region->in(k), NULL);
2618                   if (m != mem) {
2619                     DEBUG_ONLY(if (trace) { tty->print("ZZZ setting memory of phi %d", k); uu->dump(); });
2620                     newmm = clone_merge_mem(u, mem, m, _phase->ctrl_or_self(m), i);
2621                     if (newmm != u) {
2622                       _phase->igvn().replace_input_of(uu, k, newmm);
2623                       nb++;
2624                       --jmax;
2625                     }
2626                   }
2627                 }
2628               }
2629               if (nb > 0) {
2630                 --j;
2631               }
2632             } else {
2633               Node* m = find_mem(_phase->ctrl_or_self(uu), uu);
2634               if (m != mem) {
2635                 DEBUG_ONLY(if (trace) { tty->print("ZZZ setting memory of use"); uu->dump(); });
2636                 newmm = clone_merge_mem(u, mem, m, _phase->ctrl_or_self(m), i);
2637                 if (newmm != u) {
2638                   _phase->igvn().replace_input_of(uu, uu->find_edge(u), newmm);
2639                   --j, --jmax;
2640                 }
2641               }
2642             }
2643           }
2644         }
2645       } else if (u->is_Phi()) {
2646         assert(u->bottom_type() == Type::MEMORY, "what else?");
2647         if (_phase->C->get_alias_index(u->adr_type()) == alias || u->adr_type() == TypePtr::BOTTOM) {
2648           Node* region = u->in(0);
2649           bool replaced = false;
2650           for (uint j = 1; j < u->req(); j++) {
2651             if (u->in(j) == mem) {
2652               Node* m = find_mem(region->in(j), NULL);
2653               Node* nnew = m;
2654               if (m != mem) {
2655                 if (u->adr_type() == TypePtr::BOTTOM) {
2656                   mm = allocate_merge_mem(mem, m, _phase->ctrl_or_self(m));
2657                   nnew = mm;
2658                 }
2659                 DEBUG_ONLY(if (trace) { tty->print("ZZZ setting memory of phi %d", j); u->dump(); });
2660                 _phase->igvn().replace_input_of(u, j, nnew);
2661                 replaced = true;
2662               }
2663             }
2664           }
2665           if (replaced) {
2666             --i;
2667           }
2668         }
2669       } else if ((u->adr_type() == TypePtr::BOTTOM && u->Opcode() != Op_StrInflatedCopy) ||
2670                  u->adr_type() == NULL) {
2671         assert(u->adr_type() != NULL ||
2672                u->Opcode() == Op_Rethrow ||
2673                u->Opcode() == Op_Return ||
2674                u->Opcode() == Op_SafePoint ||
2675                (u->is_CallStaticJava() && u->as_CallStaticJava()->uncommon_trap_request() != 0) ||
2676                (u->is_CallStaticJava() && u->as_CallStaticJava()->_entry_point == OptoRuntime::rethrow_stub()) ||
2677                u->Opcode() == Op_CallLeaf, "");
2678         Node* m = find_mem(_phase->ctrl_or_self(u), u);
2679         if (m != mem) {
2680           mm = allocate_merge_mem(mem, m, _phase->get_ctrl(m));
2681           _phase->igvn().replace_input_of(u, u->find_edge(mem), mm);
2682           --i;
2683         }
2684       } else if (_phase->C->get_alias_index(u->adr_type()) == alias) {
2685         Node* m = find_mem(_phase->ctrl_or_self(u), u);
2686         if (m != mem) {
2687           DEBUG_ONLY(if (trace) { tty->print("ZZZ setting memory of use"); u->dump(); });
2688           _phase->igvn().replace_input_of(u, u->find_edge(mem), m);
2689           --i;
2690         }
2691       } else if (u->adr_type() != TypePtr::BOTTOM &&
2692                  _memory_nodes[_phase->ctrl_or_self(u)->_idx] == u) {
2693         Node* m = find_mem(_phase->ctrl_or_self(u), u);
2694         assert(m != mem, "");
2695         // u is on the wrong slice...
2696         assert(u->is_ClearArray(), "");
2697         DEBUG_ONLY(if (trace) { tty->print("ZZZ setting memory of use"); u->dump(); });
2698         _phase->igvn().replace_input_of(u, u->find_edge(mem), m);
2699         --i;
2700       }
2701     }
2702   }
2703 #ifdef ASSERT
2704   assert(new_mem->outcnt() > 0, "");
2705   for (int i = 0; i < phis.length(); i++) {
2706     Node* n = phis.at(i);
2707     assert(n->outcnt() > 0, "new phi must have uses now");
2708   }
2709 #endif
2710 }
2711 
2712 MergeMemNode* MemoryGraphFixer::allocate_merge_mem(Node* mem, Node* rep_proj, Node* rep_ctrl) const {
2713   MergeMemNode* mm = MergeMemNode::make(mem);
2714   mm->set_memory_at(_alias, rep_proj);
2715   _phase->register_new_node(mm, rep_ctrl);
2716   return mm;
2717 }
2718 
2719 MergeMemNode* MemoryGraphFixer::clone_merge_mem(Node* u, Node* mem, Node* rep_proj, Node* rep_ctrl, DUIterator& i) const {
2720   MergeMemNode* newmm = NULL;
2721   MergeMemNode* u_mm = u->as_MergeMem();
2722   Node* c = _phase->get_ctrl(u);
2723   if (_phase->is_dominator(c, rep_ctrl)) {
2724     c = rep_ctrl;
2725   } else {
2726     assert(_phase->is_dominator(rep_ctrl, c), "one must dominate the other");
2727   }
2728   if (u->outcnt() == 1) {
2729     if (u->req() > (uint)_alias && u->in(_alias) == mem) {
2730       _phase->igvn().replace_input_of(u, _alias, rep_proj);
2731       --i;
2732     } else {
2733       _phase->igvn().rehash_node_delayed(u);
2734       u_mm->set_memory_at(_alias, rep_proj);
2735     }
2736     newmm = u_mm;
2737     _phase->set_ctrl_and_loop(u, c);
2738   } else {
2739     // can't simply clone u and then change one of its input because
2740     // it adds and then removes an edge which messes with the
2741     // DUIterator
2742     newmm = MergeMemNode::make(u_mm->base_memory());
2743     for (uint j = 0; j < u->req(); j++) {
2744       if (j < newmm->req()) {
2745         if (j == (uint)_alias) {
2746           newmm->set_req(j, rep_proj);
2747         } else if (newmm->in(j) != u->in(j)) {
2748           newmm->set_req(j, u->in(j));
2749         }
2750       } else if (j == (uint)_alias) {
2751         newmm->add_req(rep_proj);
2752       } else {
2753         newmm->add_req(u->in(j));
2754       }
2755     }
2756     if ((uint)_alias >= u->req()) {
2757       newmm->set_memory_at(_alias, rep_proj);
2758     }
2759     _phase->register_new_node(newmm, c);
2760   }
2761   return newmm;
2762 }
2763 
2764 bool MemoryGraphFixer::should_process_phi(Node* phi) const {
2765   if (phi->adr_type() == TypePtr::BOTTOM) {
2766     Node* region = phi->in(0);
2767     for (DUIterator_Fast jmax, j = region->fast_outs(jmax); j < jmax; j++) {
2768       Node* uu = region->fast_out(j);
2769       if (uu->is_Phi() && uu != phi && uu->bottom_type() == Type::MEMORY && _phase->C->get_alias_index(uu->adr_type()) == _alias) {
2770         return false;
2771       }
2772     }
2773     return true;
2774   }
2775   return _phase->C->get_alias_index(phi->adr_type()) == _alias;
2776 }
2777 
2778 void MemoryGraphFixer::fix_memory_uses(Node* mem, Node* replacement, Node* rep_proj, Node* rep_ctrl) const {
2779   uint last = _phase-> C->unique();
2780   MergeMemNode* mm = NULL;
2781   assert(mem->bottom_type() == Type::MEMORY, "");
2782   for (DUIterator i = mem->outs(); mem->has_out(i); i++) {
2783     Node* u = mem->out(i);
2784     if (u != replacement && u->_idx < last) {
2785       if (u->is_MergeMem()) {
2786         MergeMemNode* u_mm = u->as_MergeMem();
2787         if (u_mm->memory_at(_alias) == mem) {
2788           MergeMemNode* newmm = NULL;
2789           for (DUIterator_Fast jmax, j = u->fast_outs(jmax); j < jmax; j++) {
2790             Node* uu = u->fast_out(j);
2791             assert(!uu->is_MergeMem(), "chain of MergeMems?");
2792             if (uu->is_Phi()) {
2793               if (should_process_phi(uu)) {
2794                 Node* region = uu->in(0);
2795                 int nb = 0;
2796                 for (uint k = 1; k < uu->req(); k++) {
2797                   if (uu->in(k) == u && _phase->is_dominator(rep_ctrl, region->in(k))) {
2798                     if (newmm == NULL) {
2799                       newmm = clone_merge_mem(u, mem, rep_proj, rep_ctrl, i);
2800                     }
2801                     if (newmm != u) {
2802                       _phase->igvn().replace_input_of(uu, k, newmm);
2803                       nb++;
2804                       --jmax;
2805                     }
2806                   }
2807                 }
2808                 if (nb > 0) {
2809                   --j;
2810                 }
2811               }
2812             } else {
2813               if (rep_ctrl != uu && ShenandoahBarrierC2Support::is_dominator(rep_ctrl, _phase->ctrl_or_self(uu), replacement, uu, _phase)) {
2814                 if (newmm == NULL) {
2815                   newmm = clone_merge_mem(u, mem, rep_proj, rep_ctrl, i);
2816                 }
2817                 if (newmm != u) {
2818                   _phase->igvn().replace_input_of(uu, uu->find_edge(u), newmm);
2819                   --j, --jmax;
2820                 }
2821               }
2822             }
2823           }
2824         }
2825       } else if (u->is_Phi()) {
2826         assert(u->bottom_type() == Type::MEMORY, "what else?");
2827         Node* region = u->in(0);
2828         if (should_process_phi(u)) {
2829           bool replaced = false;
2830           for (uint j = 1; j < u->req(); j++) {
2831             if (u->in(j) == mem && _phase->is_dominator(rep_ctrl, region->in(j))) {
2832               Node* nnew = rep_proj;
2833               if (u->adr_type() == TypePtr::BOTTOM) {
2834                 if (mm == NULL) {
2835                   mm = allocate_merge_mem(mem, rep_proj, rep_ctrl);
2836                 }
2837                 nnew = mm;
2838               }
2839               _phase->igvn().replace_input_of(u, j, nnew);
2840               replaced = true;
2841             }
2842           }
2843           if (replaced) {
2844             --i;
2845           }
2846 
2847         }
2848       } else if ((u->adr_type() == TypePtr::BOTTOM && u->Opcode() != Op_StrInflatedCopy) ||
2849                  u->adr_type() == NULL) {
2850         assert(u->adr_type() != NULL ||
2851                u->Opcode() == Op_Rethrow ||
2852                u->Opcode() == Op_Return ||
2853                u->Opcode() == Op_SafePoint ||
2854                u->Opcode() == Op_StoreIConditional ||
2855                u->Opcode() == Op_StoreLConditional ||
2856                (u->is_CallStaticJava() && u->as_CallStaticJava()->uncommon_trap_request() != 0) ||
2857                (u->is_CallStaticJava() && u->as_CallStaticJava()->_entry_point == OptoRuntime::rethrow_stub()) ||
2858                u->Opcode() == Op_CallLeaf, "%s", u->Name());
2859         if (ShenandoahBarrierC2Support::is_dominator(rep_ctrl, _phase->ctrl_or_self(u), replacement, u, _phase)) {
2860           if (mm == NULL) {
2861             mm = allocate_merge_mem(mem, rep_proj, rep_ctrl);
2862           }
2863           _phase->igvn().replace_input_of(u, u->find_edge(mem), mm);
2864           --i;
2865         }
2866       } else if (_phase->C->get_alias_index(u->adr_type()) == _alias) {
2867         if (ShenandoahBarrierC2Support::is_dominator(rep_ctrl, _phase->ctrl_or_self(u), replacement, u, _phase)) {
2868           _phase->igvn().replace_input_of(u, u->find_edge(mem), rep_proj);
2869           --i;
2870         }
2871       }
2872     }
2873   }
2874 }
2875 
2876 ShenandoahLoadReferenceBarrierNode::ShenandoahLoadReferenceBarrierNode(Node* ctrl, Node* obj, bool native)
2877 : Node(ctrl, obj), _native(native) {
2878   ShenandoahBarrierSetC2::bsc2()->state()->add_load_reference_barrier(this);
2879 }
2880 
2881 bool ShenandoahLoadReferenceBarrierNode::is_native() const {
2882   return _native;
2883 }
2884 
2885 uint ShenandoahLoadReferenceBarrierNode::size_of() const {
2886   return sizeof(*this);
2887 }
2888 
2889 uint ShenandoahLoadReferenceBarrierNode::hash() const {
2890   return Node::hash() + (_native ? 1 : 0);
2891 }
2892 
2893 bool ShenandoahLoadReferenceBarrierNode::cmp( const Node &n ) const {
2894   return Node::cmp(n) && n.Opcode() == Op_ShenandoahLoadReferenceBarrier &&
2895          _native == ((const ShenandoahLoadReferenceBarrierNode&)n)._native;
2896 }
2897 
2898 const Type* ShenandoahLoadReferenceBarrierNode::bottom_type() const {
2899   if (in(ValueIn) == NULL || in(ValueIn)->is_top()) {
2900     return Type::TOP;
2901   }
2902   const Type* t = in(ValueIn)->bottom_type();
2903   if (t == TypePtr::NULL_PTR) {
2904     return t;
2905   }
2906   return t->is_oopptr();
2907 }
2908 
2909 const Type* ShenandoahLoadReferenceBarrierNode::Value(PhaseGVN* phase) const {
2910   // Either input is TOP ==> the result is TOP
2911   const Type *t2 = phase->type(in(ValueIn));
2912   if( t2 == Type::TOP ) return Type::TOP;
2913 
2914   if (t2 == TypePtr::NULL_PTR) {
2915     return t2;
2916   }
2917 
2918   const Type* type = t2->is_oopptr();
2919   return type;
2920 }
2921 
2922 Node* ShenandoahLoadReferenceBarrierNode::Identity(PhaseGVN* phase) {
2923   Node* value = in(ValueIn);
2924   if (!needs_barrier(phase, value)) {
2925     return value;
2926   }
2927   return this;
2928 }
2929 
2930 bool ShenandoahLoadReferenceBarrierNode::needs_barrier(PhaseGVN* phase, Node* n) {
2931   Unique_Node_List visited;
2932   return needs_barrier_impl(phase, n, visited);
2933 }
2934 
2935 bool ShenandoahLoadReferenceBarrierNode::needs_barrier_impl(PhaseGVN* phase, Node* n, Unique_Node_List &visited) {
2936   if (n == NULL) return false;
2937   if (visited.member(n)) {
2938     return false; // Been there.
2939   }
2940   visited.push(n);
2941 
2942   if (n->is_Allocate()) {
2943     // tty->print_cr("optimize barrier on alloc");
2944     return false;
2945   }
2946   if (n->is_Call()) {
2947     // tty->print_cr("optimize barrier on call");
2948     return false;
2949   }
2950 
2951   const Type* type = phase->type(n);
2952   if (type == Type::TOP) {
2953     return false;
2954   }
2955   if (type->make_ptr()->higher_equal(TypePtr::NULL_PTR)) {
2956     // tty->print_cr("optimize barrier on null");
2957     return false;
2958   }
2959   if (type->make_oopptr() && type->make_oopptr()->const_oop() != NULL) {
2960     // tty->print_cr("optimize barrier on constant");
2961     return false;
2962   }
2963 
2964   switch (n->Opcode()) {
2965     case Op_AddP:
2966       return true; // TODO: Can refine?
2967     case Op_LoadP:
2968     case Op_ShenandoahCompareAndExchangeN:
2969     case Op_ShenandoahCompareAndExchangeP:
2970     case Op_CompareAndExchangeN:
2971     case Op_CompareAndExchangeP:
2972     case Op_GetAndSetN:
2973     case Op_GetAndSetP:
2974       return true;
2975     case Op_Phi: {
2976       for (uint i = 1; i < n->req(); i++) {
2977         if (needs_barrier_impl(phase, n->in(i), visited)) return true;
2978       }
2979       return false;
2980     }
2981     case Op_CheckCastPP:
2982     case Op_CastPP:
2983       return needs_barrier_impl(phase, n->in(1), visited);
2984     case Op_Proj:
2985       return needs_barrier_impl(phase, n->in(0), visited);
2986     case Op_ShenandoahLoadReferenceBarrier:
2987       // tty->print_cr("optimize barrier on barrier");
2988       return false;
2989     case Op_Parm:
2990       // tty->print_cr("optimize barrier on input arg");
2991       return false;
2992     case Op_DecodeN:
2993     case Op_EncodeP:
2994       return needs_barrier_impl(phase, n->in(1), visited);
2995     case Op_LoadN:
2996       return true;
2997     case Op_CMoveN:
2998     case Op_CMoveP:
2999       return needs_barrier_impl(phase, n->in(2), visited) ||
3000              needs_barrier_impl(phase, n->in(3), visited);
3001     case Op_ShenandoahEnqueueBarrier:
3002       return needs_barrier_impl(phase, n->in(1), visited);
3003     case Op_CreateEx:
3004       return false;
3005     default:
3006       break;
3007   }
3008 #ifdef ASSERT
3009   tty->print("need barrier on?: ");
3010   tty->print_cr("ins:");
3011   n->dump(2);
3012   tty->print_cr("outs:");
3013   n->dump(-2);
3014   ShouldNotReachHere();
3015 #endif
3016   return true;
3017 }