1 /*
   2  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "opto/arraycopynode.hpp"
  27 #include "opto/graphKit.hpp"
  28 
  29 ArrayCopyNode::ArrayCopyNode(Compile* C, bool alloc_tightly_coupled)
  30   : CallNode(arraycopy_type(), NULL, TypeRawPtr::BOTTOM),
  31     _alloc_tightly_coupled(alloc_tightly_coupled),
  32     _kind(None),
  33     _arguments_validated(false),
  34     _src_type(TypeOopPtr::BOTTOM),
  35     _dest_type(TypeOopPtr::BOTTOM) {
  36   init_class_id(Class_ArrayCopy);
  37   init_flags(Flag_is_macro);
  38   C->add_macro_node(this);
  39 }
  40 
  41 uint ArrayCopyNode::size_of() const { return sizeof(*this); }
  42 
  43 ArrayCopyNode* ArrayCopyNode::make(GraphKit* kit, bool may_throw,
  44                                    Node* src, Node* src_offset,
  45                                    Node* dest, Node* dest_offset,
  46                                    Node* length,
  47                                    bool alloc_tightly_coupled,
  48                                    Node* src_klass, Node* dest_klass,
  49                                    Node* src_length, Node* dest_length) {
  50 
  51   ArrayCopyNode* ac = new ArrayCopyNode(kit->C, alloc_tightly_coupled);
  52   Node* prev_mem = kit->set_predefined_input_for_runtime_call(ac);
  53 
  54   ac->init_req(ArrayCopyNode::Src, src);
  55   ac->init_req(ArrayCopyNode::SrcPos, src_offset);
  56   ac->init_req(ArrayCopyNode::Dest, dest);
  57   ac->init_req(ArrayCopyNode::DestPos, dest_offset);
  58   ac->init_req(ArrayCopyNode::Length, length);
  59   ac->init_req(ArrayCopyNode::SrcLen, src_length);
  60   ac->init_req(ArrayCopyNode::DestLen, dest_length);
  61   ac->init_req(ArrayCopyNode::SrcKlass, src_klass);
  62   ac->init_req(ArrayCopyNode::DestKlass, dest_klass);
  63 
  64   if (may_throw) {
  65     ac->set_req(TypeFunc::I_O , kit->i_o());
  66     kit->add_safepoint_edges(ac, false);
  67   }
  68 
  69   return ac;
  70 }
  71 
  72 void ArrayCopyNode::connect_outputs(GraphKit* kit) {
  73   kit->set_all_memory_call(this, true);
  74   kit->set_control(kit->gvn().transform(new ProjNode(this,TypeFunc::Control)));
  75   kit->set_i_o(kit->gvn().transform(new ProjNode(this, TypeFunc::I_O)));
  76   kit->make_slow_call_ex(this, kit->env()->Throwable_klass(), true);
  77   kit->set_all_memory_call(this);
  78 }
  79 
  80 #ifndef PRODUCT
  81 const char* ArrayCopyNode::_kind_names[] = {"arraycopy", "arraycopy, validated arguments", "clone", "oop array clone", "CopyOf", "CopyOfRange"};
  82 
  83 void ArrayCopyNode::dump_spec(outputStream *st) const {
  84   CallNode::dump_spec(st);
  85   st->print(" (%s%s)", _kind_names[_kind], _alloc_tightly_coupled ? ", tightly coupled allocation" : "");
  86 }
  87 
  88 void ArrayCopyNode::dump_comp_spec(outputStream* st) const {
  89   st->print("%s%s", _kind_names[_kind], _alloc_tightly_coupled ? ",tight" : "");
  90 }
  91 #endif
  92 
  93 intptr_t ArrayCopyNode::get_length_if_constant(PhaseGVN *phase) const {
  94   // check that length is constant
  95   Node* length = in(ArrayCopyNode::Length);
  96   const Type* length_type = phase->type(length);
  97 
  98   if (length_type == Type::TOP) {
  99     return -1;
 100   }
 101 
 102   assert(is_clonebasic() || is_arraycopy() || is_copyof() || is_copyofrange(), "unexpected array copy type");
 103 
 104   return is_clonebasic() ? length->find_intptr_t_con(-1) : length->find_int_con(-1);
 105 }
 106 
 107 int ArrayCopyNode::get_count(PhaseGVN *phase) const {
 108   Node* src = in(ArrayCopyNode::Src);
 109   const Type* src_type = phase->type(src);
 110 
 111   if (is_clonebasic()) {
 112     if (src_type->isa_instptr()) {
 113       const TypeInstPtr* inst_src = src_type->is_instptr();
 114       ciInstanceKlass* ik = inst_src->klass()->as_instance_klass();
 115       // ciInstanceKlass::nof_nonstatic_fields() doesn't take injected
 116       // fields into account. They are rare anyway so easier to simply
 117       // skip instances with injected fields.
 118       if ((!inst_src->klass_is_exact() && (ik->is_interface() || ik->has_subklass())) || ik->has_injected_fields()) {
 119         return -1;
 120       }
 121       int nb_fields = ik->nof_nonstatic_fields();
 122       return nb_fields;
 123     } else {
 124       const TypeAryPtr* ary_src = src_type->isa_aryptr();
 125       assert (ary_src != NULL, "not an array or instance?");
 126       // clone passes a length as a rounded number of longs. If we're
 127       // cloning an array we'll do it element by element. If the
 128       // length input to ArrayCopyNode is constant, length of input
 129       // array must be too.
 130 
 131       assert((get_length_if_constant(phase) == -1) == !ary_src->size()->is_con() ||
 132              phase->is_IterGVN(), "inconsistent");
 133 
 134       if (ary_src->size()->is_con()) {
 135         return ary_src->size()->get_con();
 136       }
 137       return -1;
 138     }
 139   }
 140 
 141   return get_length_if_constant(phase);
 142 }
 143 
 144 Node* ArrayCopyNode::try_clone_instance(PhaseGVN *phase, bool can_reshape, int count) {
 145   if (!is_clonebasic()) {
 146     return NULL;
 147   }
 148 
 149   Node* src = in(ArrayCopyNode::Src);
 150   Node* dest = in(ArrayCopyNode::Dest);
 151   Node* ctl = in(TypeFunc::Control);
 152   Node* in_mem = in(TypeFunc::Memory);
 153 
 154   const Type* src_type = phase->type(src);
 155 
 156   assert(src->is_AddP(), "should be base + off");
 157   assert(dest->is_AddP(), "should be base + off");
 158   Node* base_src = src->in(AddPNode::Base);
 159   Node* base_dest = dest->in(AddPNode::Base);
 160 
 161   MergeMemNode* mem = MergeMemNode::make(in_mem);
 162 
 163   const TypeInstPtr* inst_src = src_type->isa_instptr();
 164 
 165   if (inst_src == NULL) {
 166     return NULL;
 167   }
 168 
 169   if (!inst_src->klass_is_exact()) {
 170     ciInstanceKlass* ik = inst_src->klass()->as_instance_klass();
 171     assert(!ik->is_interface() && !ik->has_subklass(), "inconsistent klass hierarchy");
 172     phase->C->dependencies()->assert_leaf_type(ik);
 173   }
 174 
 175   ciInstanceKlass* ik = inst_src->klass()->as_instance_klass();
 176   assert(ik->nof_nonstatic_fields() <= ArrayCopyLoadStoreMaxElem, "too many fields");
 177 
 178   for (int i = 0; i < count; i++) {
 179     ciField* field = ik->nonstatic_field_at(i);
 180     int fieldidx = phase->C->alias_type(field)->index();
 181     const TypePtr* adr_type = phase->C->alias_type(field)->adr_type();
 182     Node* off = phase->MakeConX(field->offset());
 183     Node* next_src = phase->transform(new AddPNode(base_src,base_src,off));
 184     Node* next_dest = phase->transform(new AddPNode(base_dest,base_dest,off));
 185     BasicType bt = field->layout_type();
 186 
 187     const Type *type;
 188     if (bt == T_OBJECT) {
 189       if (!field->type()->is_loaded()) {
 190         type = TypeInstPtr::BOTTOM;
 191       } else {
 192         ciType* field_klass = field->type();
 193         type = TypeOopPtr::make_from_klass(field_klass->as_klass());
 194       }
 195     } else {
 196       type = Type::get_const_basic_type(bt);
 197     }
 198 
 199     Node* v = LoadNode::make(*phase, ctl, mem->memory_at(fieldidx), next_src, adr_type, type, bt, MemNode::unordered);
 200     v = phase->transform(v);
 201     Node* s = StoreNode::make(*phase, ctl, mem->memory_at(fieldidx), next_dest, adr_type, v, bt, MemNode::unordered);
 202     s = phase->transform(s);
 203     mem->set_memory_at(fieldidx, s);
 204   }
 205 
 206   if (!finish_transform(phase, can_reshape, ctl, mem)) {
 207     return NULL;
 208   }
 209 
 210   return mem;
 211 }
 212 
 213 bool ArrayCopyNode::prepare_array_copy(PhaseGVN *phase, bool can_reshape,
 214                                        Node*& adr_src,
 215                                        Node*& base_src,
 216                                        Node*& adr_dest,
 217                                        Node*& base_dest,
 218                                        BasicType& copy_type,
 219                                        const Type*& value_type,
 220                                        bool& disjoint_bases) {
 221   Node* src = in(ArrayCopyNode::Src);
 222   Node* dest = in(ArrayCopyNode::Dest);
 223   const Type* src_type = phase->type(src);
 224   const TypeAryPtr* ary_src = src_type->isa_aryptr();
 225 
 226   if (is_arraycopy() || is_copyofrange() || is_copyof()) {
 227     const Type* dest_type = phase->type(dest);
 228     const TypeAryPtr* ary_dest = dest_type->isa_aryptr();
 229     Node* src_offset = in(ArrayCopyNode::SrcPos);
 230     Node* dest_offset = in(ArrayCopyNode::DestPos);
 231 
 232     // newly allocated object is guaranteed to not overlap with source object
 233     disjoint_bases = is_alloc_tightly_coupled();
 234 
 235     if (ary_src  == NULL || ary_src->klass()  == NULL ||
 236         ary_dest == NULL || ary_dest->klass() == NULL) {
 237       // We don't know if arguments are arrays
 238       return false;
 239     }
 240 
 241     BasicType src_elem  = ary_src->klass()->as_array_klass()->element_type()->basic_type();
 242     BasicType dest_elem = ary_dest->klass()->as_array_klass()->element_type()->basic_type();
 243     if (src_elem  == T_ARRAY)  src_elem  = T_OBJECT;
 244     if (dest_elem == T_ARRAY)  dest_elem = T_OBJECT;
 245 
 246     if (src_elem != dest_elem || dest_elem == T_VOID) {
 247       // We don't know if arguments are arrays of the same type
 248       return false;
 249     }
 250 
 251     if (dest_elem == T_OBJECT && (!is_alloc_tightly_coupled() || !GraphKit::use_ReduceInitialCardMarks())) {
 252       // It's an object array copy but we can't emit the card marking
 253       // that is needed
 254       return false;
 255     }
 256 
 257     value_type = ary_src->elem();
 258 
 259     base_src = src;
 260     base_dest = dest;
 261 
 262     uint shift  = exact_log2(type2aelembytes(dest_elem));
 263     uint header = arrayOopDesc::base_offset_in_bytes(dest_elem);
 264 
 265     adr_src = src;
 266     adr_dest = dest;
 267 
 268     src_offset = Compile::conv_I2X_index(phase, src_offset, ary_src->size());
 269     dest_offset = Compile::conv_I2X_index(phase, dest_offset, ary_dest->size());
 270 
 271     Node* src_scale = phase->transform(new LShiftXNode(src_offset, phase->intcon(shift)));
 272     Node* dest_scale = phase->transform(new LShiftXNode(dest_offset, phase->intcon(shift)));
 273 
 274     adr_src = phase->transform(new AddPNode(base_src, adr_src, src_scale));
 275     adr_dest = phase->transform(new AddPNode(base_dest, adr_dest, dest_scale));
 276 
 277     adr_src = new AddPNode(base_src, adr_src, phase->MakeConX(header));
 278     adr_dest = new AddPNode(base_dest, adr_dest, phase->MakeConX(header));
 279 
 280     adr_src = phase->transform(adr_src);
 281     adr_dest = phase->transform(adr_dest);
 282 
 283     copy_type = dest_elem;
 284   } else {
 285     assert (is_clonebasic(), "should be");
 286 
 287     disjoint_bases = true;
 288     assert(src->is_AddP(), "should be base + off");
 289     assert(dest->is_AddP(), "should be base + off");
 290     adr_src = src;
 291     base_src = src->in(AddPNode::Base);
 292     adr_dest = dest;
 293     base_dest = dest->in(AddPNode::Base);
 294 
 295     assert(phase->type(src->in(AddPNode::Offset))->is_intptr_t()->get_con() == phase->type(dest->in(AddPNode::Offset))->is_intptr_t()->get_con(), "same start offset?");
 296     BasicType elem = ary_src->klass()->as_array_klass()->element_type()->basic_type();
 297     if (elem == T_ARRAY)  elem = T_OBJECT;
 298 
 299     int diff = arrayOopDesc::base_offset_in_bytes(elem) - phase->type(src->in(AddPNode::Offset))->is_intptr_t()->get_con();
 300     assert(diff >= 0, "clone should not start after 1st array element");
 301     if (diff > 0) {
 302       adr_src = phase->transform(new AddPNode(base_src, adr_src, phase->MakeConX(diff)));
 303       adr_dest = phase->transform(new AddPNode(base_dest, adr_dest, phase->MakeConX(diff)));
 304     }
 305 
 306     copy_type = elem;
 307     value_type = ary_src->elem();
 308   }
 309   return true;
 310 }
 311 
 312 const TypePtr* ArrayCopyNode::get_address_type(PhaseGVN *phase, Node* n) {
 313   const Type* at = phase->type(n);
 314   assert(at != Type::TOP, "unexpected type");
 315   const TypePtr* atp = at->isa_ptr();
 316   // adjust atp to be the correct array element address type
 317   atp = atp->add_offset(Type::OffsetBot);
 318   return atp;
 319 }
 320 
 321 void ArrayCopyNode::array_copy_test_overlap(PhaseGVN *phase, bool can_reshape, bool disjoint_bases, int count, Node*& forward_ctl, Node*& backward_ctl) {
 322   Node* ctl = in(TypeFunc::Control);
 323   if (!disjoint_bases && count > 1) {
 324     Node* src_offset = in(ArrayCopyNode::SrcPos);
 325     Node* dest_offset = in(ArrayCopyNode::DestPos);
 326     assert(src_offset != NULL && dest_offset != NULL, "should be");
 327     Node* cmp = phase->transform(new CmpINode(src_offset, dest_offset));
 328     Node *bol = phase->transform(new BoolNode(cmp, BoolTest::lt));
 329     IfNode *iff = new IfNode(ctl, bol, PROB_FAIR, COUNT_UNKNOWN);
 330 
 331     phase->transform(iff);
 332 
 333     forward_ctl = phase->transform(new IfFalseNode(iff));
 334     backward_ctl = phase->transform(new IfTrueNode(iff));
 335   } else {
 336     forward_ctl = ctl;
 337   }
 338 }
 339 
 340 Node* ArrayCopyNode::array_copy_forward(PhaseGVN *phase,
 341                                         bool can_reshape,
 342                                         Node* forward_ctl,
 343                                         Node* start_mem_src,
 344                                         Node* start_mem_dest,
 345                                         const TypePtr* atp_src,
 346                                         const TypePtr* atp_dest,
 347                                         Node* adr_src,
 348                                         Node* base_src,
 349                                         Node* adr_dest,
 350                                         Node* base_dest,
 351                                         BasicType copy_type,
 352                                         const Type* value_type,
 353                                         int count) {
 354   Node* mem = phase->C->top();
 355   if (!forward_ctl->is_top()) {
 356     // copy forward
 357     mem = start_mem_dest;
 358 
 359     if (count > 0) {
 360       Node* v = LoadNode::make(*phase, forward_ctl, start_mem_src, adr_src, atp_src, value_type, copy_type, MemNode::unordered);
 361       v = phase->transform(v);
 362       mem = StoreNode::make(*phase, forward_ctl, mem, adr_dest, atp_dest, v, copy_type, MemNode::unordered);
 363       mem = phase->transform(mem);
 364       for (int i = 1; i < count; i++) {
 365         Node* off  = phase->MakeConX(type2aelembytes(copy_type) * i);
 366         Node* next_src = phase->transform(new AddPNode(base_src,adr_src,off));
 367         Node* next_dest = phase->transform(new AddPNode(base_dest,adr_dest,off));
 368         v = LoadNode::make(*phase, forward_ctl, mem, next_src, atp_src, value_type, copy_type, MemNode::unordered);
 369         v = phase->transform(v);
 370         mem = StoreNode::make(*phase, forward_ctl,mem,next_dest,atp_dest,v, copy_type, MemNode::unordered);
 371         mem = phase->transform(mem);
 372       }
 373     } else if(can_reshape) {
 374       PhaseIterGVN* igvn = phase->is_IterGVN();
 375       igvn->_worklist.push(adr_src);
 376       igvn->_worklist.push(adr_dest);
 377     }
 378   }
 379   return mem;
 380 }
 381 
 382 Node* ArrayCopyNode::array_copy_backward(PhaseGVN *phase,
 383                                          bool can_reshape,
 384                                          Node* backward_ctl,
 385                                          Node* start_mem_src,
 386                                          Node* start_mem_dest,
 387                                          const TypePtr* atp_src,
 388                                          const TypePtr* atp_dest,
 389                                          Node* adr_src,
 390                                          Node* base_src,
 391                                          Node* adr_dest,
 392                                          Node* base_dest,
 393                                          BasicType copy_type,
 394                                          const Type* value_type,
 395                                          int count) {
 396   Node* mem = phase->C->top();
 397   if (!backward_ctl->is_top()) {
 398     // copy backward
 399     mem = start_mem_dest;
 400 
 401     if (count > 0) {
 402       for (int i = count-1; i >= 1; i--) {
 403         Node* off  = phase->MakeConX(type2aelembytes(copy_type) * i);
 404         Node* next_src = phase->transform(new AddPNode(base_src,adr_src,off));
 405         Node* next_dest = phase->transform(new AddPNode(base_dest,adr_dest,off));
 406         Node* v = LoadNode::make(*phase, backward_ctl, mem, next_src, atp_src, value_type, copy_type, MemNode::unordered);
 407         v = phase->transform(v);
 408         mem = StoreNode::make(*phase, backward_ctl,mem,next_dest,atp_dest,v, copy_type, MemNode::unordered);
 409         mem = phase->transform(mem);
 410       }
 411       Node* v = LoadNode::make(*phase, backward_ctl, mem, adr_src, atp_src, value_type, copy_type, MemNode::unordered);
 412       v = phase->transform(v);
 413       mem = StoreNode::make(*phase, backward_ctl, mem, adr_dest, atp_dest, v, copy_type, MemNode::unordered);
 414       mem = phase->transform(mem);
 415     } else if(can_reshape) {
 416       PhaseIterGVN* igvn = phase->is_IterGVN();
 417       igvn->_worklist.push(adr_src);
 418       igvn->_worklist.push(adr_dest);
 419     }
 420   }
 421   return mem;
 422 }
 423 
 424 bool ArrayCopyNode::finish_transform(PhaseGVN *phase, bool can_reshape,
 425                                      Node* ctl, Node *mem) {
 426   if (can_reshape) {
 427     PhaseIterGVN* igvn = phase->is_IterGVN();
 428     igvn->set_delay_transform(false);
 429     if (is_clonebasic()) {
 430       Node* out_mem = proj_out(TypeFunc::Memory);
 431 
 432       if (out_mem->outcnt() != 1 || !out_mem->raw_out(0)->is_MergeMem() ||
 433           out_mem->raw_out(0)->outcnt() != 1 || !out_mem->raw_out(0)->raw_out(0)->is_MemBar()) {
 434         assert(!GraphKit::use_ReduceInitialCardMarks(), "can only happen with card marking");
 435         return false;
 436       }
 437 
 438       igvn->replace_node(out_mem->raw_out(0), mem);
 439 
 440       Node* out_ctl = proj_out(TypeFunc::Control);
 441       igvn->replace_node(out_ctl, ctl);
 442     } else {
 443       // replace fallthrough projections of the ArrayCopyNode by the
 444       // new memory, control and the input IO.
 445       CallProjections callprojs;
 446       extract_projections(&callprojs, true, false);
 447 
 448       if (callprojs.fallthrough_ioproj != NULL) {
 449         igvn->replace_node(callprojs.fallthrough_ioproj, in(TypeFunc::I_O));
 450       }
 451       if (callprojs.fallthrough_memproj != NULL) {
 452         igvn->replace_node(callprojs.fallthrough_memproj, mem);
 453       }
 454       if (callprojs.fallthrough_catchproj != NULL) {
 455         igvn->replace_node(callprojs.fallthrough_catchproj, ctl);
 456       }
 457 
 458       // The ArrayCopyNode is not disconnected. It still has the
 459       // projections for the exception case. Replace current
 460       // ArrayCopyNode with a dummy new one with a top() control so
 461       // that this part of the graph stays consistent but is
 462       // eventually removed.
 463 
 464       set_req(0, phase->C->top());
 465       remove_dead_region(phase, can_reshape);
 466     }
 467   } else {
 468     if (in(TypeFunc::Control) != ctl) {
 469       // we can't return new memory and control from Ideal at parse time
 470       assert(!is_clonebasic(), "added control for clone?");
 471       return false;
 472     }
 473   }
 474   return true;
 475 }
 476 
 477 
 478 Node *ArrayCopyNode::Ideal(PhaseGVN *phase, bool can_reshape) {
 479   if (remove_dead_region(phase, can_reshape))  return this;
 480 
 481   if (StressArrayCopyMacroNode && !can_reshape) {
 482     phase->record_for_igvn(this);
 483     return NULL;
 484   }
 485 
 486   // See if it's a small array copy and we can inline it as
 487   // loads/stores
 488   // Here we can only do:
 489   // - arraycopy if all arguments were validated before and we don't
 490   // need card marking
 491   // - clone for which we don't need to do card marking
 492 
 493   if (!is_clonebasic() && !is_arraycopy_validated() &&
 494       !is_copyofrange_validated() && !is_copyof_validated()) {
 495     return NULL;
 496   }
 497 
 498   assert(in(TypeFunc::Control) != NULL &&
 499          in(TypeFunc::Memory) != NULL &&
 500          in(ArrayCopyNode::Src) != NULL &&
 501          in(ArrayCopyNode::Dest) != NULL &&
 502          in(ArrayCopyNode::Length) != NULL &&
 503          ((in(ArrayCopyNode::SrcPos) != NULL && in(ArrayCopyNode::DestPos) != NULL) ||
 504           is_clonebasic()), "broken inputs");
 505 
 506   if (in(TypeFunc::Control)->is_top() ||
 507       in(TypeFunc::Memory)->is_top() ||
 508       phase->type(in(ArrayCopyNode::Src)) == Type::TOP ||
 509       phase->type(in(ArrayCopyNode::Dest)) == Type::TOP ||
 510       (in(ArrayCopyNode::SrcPos) != NULL && in(ArrayCopyNode::SrcPos)->is_top()) ||
 511       (in(ArrayCopyNode::DestPos) != NULL && in(ArrayCopyNode::DestPos)->is_top())) {
 512     return NULL;
 513   }
 514 
 515   int count = get_count(phase);
 516 
 517   if (count < 0 || count > ArrayCopyLoadStoreMaxElem) {
 518     return NULL;
 519   }
 520 
 521   Node* mem = try_clone_instance(phase, can_reshape, count);
 522   if (mem != NULL) {
 523     return mem;
 524   }
 525 
 526   Node* adr_src = NULL;
 527   Node* base_src = NULL;
 528   Node* adr_dest = NULL;
 529   Node* base_dest = NULL;
 530   BasicType copy_type = T_ILLEGAL;
 531   const Type* value_type = NULL;
 532   bool disjoint_bases = false;
 533 
 534   if (!prepare_array_copy(phase, can_reshape,
 535                           adr_src, base_src, adr_dest, base_dest,
 536                           copy_type, value_type, disjoint_bases)) {
 537     return NULL;
 538   }
 539 
 540   Node* src = in(ArrayCopyNode::Src);
 541   Node* dest = in(ArrayCopyNode::Dest);
 542   const TypePtr* atp_src = get_address_type(phase, src);
 543   const TypePtr* atp_dest = get_address_type(phase, dest);
 544   uint alias_idx_src = phase->C->get_alias_index(atp_src);
 545   uint alias_idx_dest = phase->C->get_alias_index(atp_dest);
 546 
 547   Node *in_mem = in(TypeFunc::Memory);
 548   Node *start_mem_src = in_mem;
 549   Node *start_mem_dest = in_mem;
 550   if (in_mem->is_MergeMem()) {
 551     start_mem_src = in_mem->as_MergeMem()->memory_at(alias_idx_src);
 552     start_mem_dest = in_mem->as_MergeMem()->memory_at(alias_idx_dest);
 553   }
 554 
 555 
 556   if (can_reshape) {
 557     assert(!phase->is_IterGVN()->delay_transform(), "cannot delay transforms");
 558     phase->is_IterGVN()->set_delay_transform(true);
 559   }
 560 
 561   Node* backward_ctl = phase->C->top();
 562   Node* forward_ctl = phase->C->top();
 563   array_copy_test_overlap(phase, can_reshape, disjoint_bases, count, forward_ctl, backward_ctl);
 564 
 565   Node* forward_mem = array_copy_forward(phase, can_reshape, forward_ctl,
 566                                          start_mem_src, start_mem_dest,
 567                                          atp_src, atp_dest,
 568                                          adr_src, base_src, adr_dest, base_dest,
 569                                          copy_type, value_type, count);
 570 
 571   Node* backward_mem = array_copy_backward(phase, can_reshape, backward_ctl,
 572                                            start_mem_src, start_mem_dest,
 573                                            atp_src, atp_dest,
 574                                            adr_src, base_src, adr_dest, base_dest,
 575                                            copy_type, value_type, count);
 576 
 577   Node* ctl = NULL;
 578   if (!forward_ctl->is_top() && !backward_ctl->is_top()) {
 579     ctl = new RegionNode(3);
 580     mem = new PhiNode(ctl, Type::MEMORY, atp_dest);
 581     ctl->init_req(1, forward_ctl);
 582     mem->init_req(1, forward_mem);
 583     ctl->init_req(2, backward_ctl);
 584     mem->init_req(2, backward_mem);
 585     ctl = phase->transform(ctl);
 586     mem = phase->transform(mem);
 587   } else if (!forward_ctl->is_top()) {
 588     ctl = forward_ctl;
 589     mem = forward_mem;
 590   } else {
 591     assert(!backward_ctl->is_top(), "no copy?");
 592     ctl = backward_ctl;
 593     mem = backward_mem;
 594   }
 595 
 596   if (can_reshape) {
 597     assert(phase->is_IterGVN()->delay_transform(), "should be delaying transforms");
 598     phase->is_IterGVN()->set_delay_transform(false);
 599   }
 600 
 601   MergeMemNode* out_mem = MergeMemNode::make(in_mem);
 602   out_mem->set_memory_at(alias_idx_dest, mem);
 603   mem = out_mem;
 604 
 605   if (!finish_transform(phase, can_reshape, ctl, mem)) {
 606     return NULL;
 607   }
 608 
 609   return mem;
 610 }
 611 
 612 bool ArrayCopyNode::may_modify(const TypeOopPtr *t_oop, PhaseTransform *phase) {
 613   Node* dest = in(ArrayCopyNode::Dest);
 614   if (dest->is_top()) {
 615     return false;
 616   }
 617   const TypeOopPtr* dest_t = phase->type(dest)->is_oopptr();
 618   assert(!dest_t->is_known_instance() || _dest_type->is_known_instance(), "result of EA not recorded");
 619   assert(in(ArrayCopyNode::Src)->is_top() || !phase->type(in(ArrayCopyNode::Src))->is_oopptr()->is_known_instance() ||
 620          _src_type->is_known_instance(), "result of EA not recorded");
 621 
 622   if (_dest_type != TypeOopPtr::BOTTOM || t_oop->is_known_instance()) {
 623     assert(_dest_type == TypeOopPtr::BOTTOM || _dest_type->is_known_instance(), "result of EA is known instance");
 624     return t_oop->instance_id() == _dest_type->instance_id();
 625   }
 626 
 627   return CallNode::may_modify_arraycopy_helper(dest_t, t_oop, phase);
 628 }