1 /*
  2  * Copyright (c) 2016, 2023, 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 "gc/shared/barrierSet.hpp"
 27 #include "gc/shared/c2/barrierSetC2.hpp"
 28 #include "gc/shared/c2/cardTableBarrierSetC2.hpp"
 29 #include "gc/shared/gc_globals.hpp"
 30 #include "opto/arraycopynode.hpp"
 31 #include "opto/graphKit.hpp"
 32 #include "runtime/sharedRuntime.hpp"
 33 #include "utilities/macros.hpp"
 34 #include "utilities/powerOfTwo.hpp"
 35 
 36 ArrayCopyNode::ArrayCopyNode(Compile* C, bool alloc_tightly_coupled, bool has_negative_length_guard)
 37   : CallNode(arraycopy_type(), nullptr, TypePtr::BOTTOM),
 38     _kind(None),
 39     _alloc_tightly_coupled(alloc_tightly_coupled),
 40     _has_negative_length_guard(has_negative_length_guard),
 41     _arguments_validated(false),
 42     _src_type(TypeOopPtr::BOTTOM),
 43     _dest_type(TypeOopPtr::BOTTOM) {
 44   init_class_id(Class_ArrayCopy);
 45   init_flags(Flag_is_macro);
 46   C->add_macro_node(this);
 47 }
 48 
 49 uint ArrayCopyNode::size_of() const { return sizeof(*this); }
 50 
 51 ArrayCopyNode* ArrayCopyNode::make(GraphKit* kit, bool may_throw,
 52                                    Node* src, Node* src_offset,
 53                                    Node* dest, Node* dest_offset,
 54                                    Node* length,
 55                                    bool alloc_tightly_coupled,
 56                                    bool has_negative_length_guard,
 57                                    Node* src_klass, Node* dest_klass,
 58                                    Node* src_length, Node* dest_length) {
 59 
 60   ArrayCopyNode* ac = new ArrayCopyNode(kit->C, alloc_tightly_coupled, has_negative_length_guard);
 61   kit->set_predefined_input_for_runtime_call(ac);
 62 
 63   ac->init_req(ArrayCopyNode::Src, src);
 64   ac->init_req(ArrayCopyNode::SrcPos, src_offset);
 65   ac->init_req(ArrayCopyNode::Dest, dest);
 66   ac->init_req(ArrayCopyNode::DestPos, dest_offset);
 67   ac->init_req(ArrayCopyNode::Length, length);
 68   ac->init_req(ArrayCopyNode::SrcLen, src_length);
 69   ac->init_req(ArrayCopyNode::DestLen, dest_length);
 70   ac->init_req(ArrayCopyNode::SrcKlass, src_klass);
 71   ac->init_req(ArrayCopyNode::DestKlass, dest_klass);
 72 
 73   if (may_throw) {
 74     ac->set_req(TypeFunc::I_O , kit->i_o());
 75     kit->add_safepoint_edges(ac, false);
 76   }
 77 
 78   return ac;
 79 }
 80 
 81 void ArrayCopyNode::connect_outputs(GraphKit* kit, bool deoptimize_on_exception) {
 82   kit->set_all_memory_call(this, true);
 83   kit->set_control(kit->gvn().transform(new ProjNode(this,TypeFunc::Control)));
 84   kit->set_i_o(kit->gvn().transform(new ProjNode(this, TypeFunc::I_O)));
 85   kit->make_slow_call_ex(this, kit->env()->Throwable_klass(), true, deoptimize_on_exception);
 86   kit->set_all_memory_call(this);
 87 }
 88 
 89 #ifndef PRODUCT
 90 const char* ArrayCopyNode::_kind_names[] = {"arraycopy", "arraycopy, validated arguments", "clone", "oop array clone", "CopyOf", "CopyOfRange"};
 91 
 92 void ArrayCopyNode::dump_spec(outputStream *st) const {
 93   CallNode::dump_spec(st);
 94   st->print(" (%s%s)", _kind_names[_kind], _alloc_tightly_coupled ? ", tightly coupled allocation" : "");
 95 }
 96 
 97 void ArrayCopyNode::dump_compact_spec(outputStream* st) const {
 98   st->print("%s%s", _kind_names[_kind], _alloc_tightly_coupled ? ",tight" : "");
 99 }
100 #endif
101 
102 intptr_t ArrayCopyNode::get_length_if_constant(PhaseGVN *phase) const {
103   // check that length is constant
104   Node* length = in(ArrayCopyNode::Length);
105   const Type* length_type = phase->type(length);
106 
107   if (length_type == Type::TOP) {
108     return -1;
109   }
110 
111   assert(is_clonebasic() || is_arraycopy() || is_copyof() || is_copyofrange(), "unexpected array copy type");
112 
113   return is_clonebasic() ? length->find_intptr_t_con(-1) : length->find_int_con(-1);
114 }
115 
116 int ArrayCopyNode::get_count(PhaseGVN *phase) const {
117   Node* src = in(ArrayCopyNode::Src);
118   const Type* src_type = phase->type(src);
119 
120   if (is_clonebasic()) {
121     if (src_type->isa_instptr()) {
122       const TypeInstPtr* inst_src = src_type->is_instptr();
123       ciInstanceKlass* ik = inst_src->instance_klass();
124       // ciInstanceKlass::nof_nonstatic_fields() doesn't take injected
125       // fields into account. They are rare anyway so easier to simply
126       // skip instances with injected fields.
127       if ((!inst_src->klass_is_exact() && (ik->is_interface() || ik->has_subklass())) || ik->has_injected_fields()) {
128         return -1;
129       }
130       int nb_fields = ik->nof_nonstatic_fields();
131       return nb_fields;
132     } else {
133       const TypeAryPtr* ary_src = src_type->isa_aryptr();
134       assert (ary_src != nullptr, "not an array or instance?");
135       // clone passes a length as a rounded number of longs. If we're
136       // cloning an array we'll do it element by element. If the
137       // length of the input array is constant, ArrayCopyNode::Length
138       // must be too. Note that the opposite does not need to hold,
139       // because different input array lengths (e.g. int arrays with
140       // 3 or 4 elements) might lead to the same length input
141       // (e.g. 2 double-words).
142       assert(!ary_src->size()->is_con() || (get_length_if_constant(phase) >= 0) ||
143              phase->is_IterGVN() || phase->C->inlining_incrementally() || StressReflectiveCode, "inconsistent");
144       if (ary_src->size()->is_con()) {
145         return ary_src->size()->get_con();
146       }
147       return -1;
148     }
149   }
150 
151   return get_length_if_constant(phase);
152 }
153 
154 Node* ArrayCopyNode::load(BarrierSetC2* bs, PhaseGVN *phase, Node*& ctl, MergeMemNode* mem, Node* adr, const TypePtr* adr_type, const Type *type, BasicType bt) {
155   DecoratorSet decorators = C2_READ_ACCESS | C2_CONTROL_DEPENDENT_LOAD | IN_HEAP | C2_ARRAY_COPY;
156   C2AccessValuePtr addr(adr, adr_type);
157   C2OptAccess access(*phase, ctl, mem, decorators, bt, adr->in(AddPNode::Base), addr);
158   Node* res = bs->load_at(access, type);
159   ctl = access.ctl();
160   return res;
161 }
162 
163 void ArrayCopyNode::store(BarrierSetC2* bs, PhaseGVN *phase, Node*& ctl, MergeMemNode* mem, Node* adr, const TypePtr* adr_type, Node* val, const Type *type, BasicType bt) {
164   DecoratorSet decorators = C2_WRITE_ACCESS | IN_HEAP | C2_ARRAY_COPY;
165   if (is_alloc_tightly_coupled()) {
166     decorators |= C2_TIGHTLY_COUPLED_ALLOC;
167   }
168   C2AccessValuePtr addr(adr, adr_type);
169   C2AccessValue value(val, type);
170   C2OptAccess access(*phase, ctl, mem, decorators, bt, adr->in(AddPNode::Base), addr);
171   bs->store_at(access, value);
172   ctl = access.ctl();
173 }
174 
175 
176 Node* ArrayCopyNode::try_clone_instance(PhaseGVN *phase, bool can_reshape, int count) {
177   if (!is_clonebasic()) {
178     return nullptr;
179   }
180 
181   Node* base_src = in(ArrayCopyNode::Src);
182   Node* base_dest = in(ArrayCopyNode::Dest);
183   Node* ctl = in(TypeFunc::Control);
184   Node* in_mem = in(TypeFunc::Memory);
185 
186   const Type* src_type = phase->type(base_src);
187   const TypeInstPtr* inst_src = src_type->isa_instptr();
188   if (inst_src == nullptr) {
189     return nullptr;
190   }
191 
192   MergeMemNode* mem = phase->transform(MergeMemNode::make(in_mem))->as_MergeMem();
193   if (can_reshape) {
194     phase->is_IterGVN()->_worklist.push(mem);
195   }
196 
197 
198   ciInstanceKlass* ik = inst_src->instance_klass();
199 
200   if (!inst_src->klass_is_exact()) {
201     assert(!ik->is_interface(), "inconsistent klass hierarchy");
202     if (ik->has_subklass()) {
203       // Concurrent class loading.
204       // Fail fast and return NodeSentinel to indicate that the transform failed.
205       return NodeSentinel;
206     } else {
207       phase->C->dependencies()->assert_leaf_type(ik);
208     }
209   }
210 
211   assert(ik->nof_nonstatic_fields() <= ArrayCopyLoadStoreMaxElem, "too many fields");
212 
213   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
214   for (int i = 0; i < count; i++) {
215     ciField* field = ik->nonstatic_field_at(i);
216     const TypePtr* adr_type = phase->C->alias_type(field)->adr_type();
217     Node* off = phase->MakeConX(field->offset_in_bytes());
218     Node* next_src = phase->transform(new AddPNode(base_src,base_src,off));
219     Node* next_dest = phase->transform(new AddPNode(base_dest,base_dest,off));
220     BasicType bt = field->layout_type();
221 
222     const Type *type;
223     if (bt == T_OBJECT) {
224       if (!field->type()->is_loaded()) {
225         type = TypeInstPtr::BOTTOM;
226       } else {
227         ciType* field_klass = field->type();
228         type = TypeOopPtr::make_from_klass(field_klass->as_klass());
229       }
230     } else {
231       type = Type::get_const_basic_type(bt);
232     }
233 
234     Node* v = load(bs, phase, ctl, mem, next_src, adr_type, type, bt);
235     store(bs, phase, ctl, mem, next_dest, adr_type, v, type, bt);
236   }
237 
238   if (!finish_transform(phase, can_reshape, ctl, mem)) {
239     // Return NodeSentinel to indicate that the transform failed
240     return NodeSentinel;
241   }
242 
243   return mem;
244 }
245 
246 bool ArrayCopyNode::prepare_array_copy(PhaseGVN *phase, bool can_reshape,
247                                        Node*& adr_src,
248                                        Node*& base_src,
249                                        Node*& adr_dest,
250                                        Node*& base_dest,
251                                        BasicType& copy_type,
252                                        const Type*& value_type,
253                                        bool& disjoint_bases) {
254   base_src = in(ArrayCopyNode::Src);
255   base_dest = in(ArrayCopyNode::Dest);
256   const Type* src_type = phase->type(base_src);
257   const TypeAryPtr* ary_src = src_type->isa_aryptr();
258 
259   Node* src_offset = in(ArrayCopyNode::SrcPos);
260   Node* dest_offset = in(ArrayCopyNode::DestPos);
261 
262   if (is_arraycopy() || is_copyofrange() || is_copyof()) {
263     const Type* dest_type = phase->type(base_dest);
264     const TypeAryPtr* ary_dest = dest_type->isa_aryptr();
265 
266     // newly allocated object is guaranteed to not overlap with source object
267     disjoint_bases = is_alloc_tightly_coupled();
268     if (ary_src  == nullptr || ary_src->elem()  == Type::BOTTOM ||
269         ary_dest == nullptr || ary_dest->elem() == Type::BOTTOM) {
270       // We don't know if arguments are arrays
271       return false;
272     }
273 
274     BasicType src_elem = ary_src->elem()->array_element_basic_type();
275     BasicType dest_elem = ary_dest->elem()->array_element_basic_type();
276     if (is_reference_type(src_elem, true)) src_elem = T_OBJECT;
277     if (is_reference_type(dest_elem, true)) dest_elem = T_OBJECT;
278 
279     if (src_elem != dest_elem || dest_elem == T_VOID) {
280       // We don't know if arguments are arrays of the same type
281       return false;
282     }
283 
284     BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
285     if (bs->array_copy_requires_gc_barriers(is_alloc_tightly_coupled(), dest_elem, false, false, BarrierSetC2::Optimization)) {
286       // It's an object array copy but we can't emit the card marking
287       // that is needed
288       return false;
289     }
290 
291     value_type = ary_src->elem();
292 
293     uint shift  = exact_log2(type2aelembytes(dest_elem));
294     uint header = arrayOopDesc::base_offset_in_bytes(dest_elem);
295 
296     src_offset = Compile::conv_I2X_index(phase, src_offset, ary_src->size());
297     if (src_offset->is_top()) {
298       // Offset is out of bounds (the ArrayCopyNode will be removed)
299       return false;
300     }
301     dest_offset = Compile::conv_I2X_index(phase, dest_offset, ary_dest->size());
302     if (dest_offset->is_top()) {
303       // Offset is out of bounds (the ArrayCopyNode will be removed)
304       if (can_reshape) {
305         // record src_offset, so it can be deleted later (if it is dead)
306         phase->is_IterGVN()->_worklist.push(src_offset);
307       }
308       return false;
309     }
310 
311     Node* hook = new Node(1);
312     hook->init_req(0, dest_offset);
313 
314     Node* src_scale  = phase->transform(new LShiftXNode(src_offset, phase->intcon(shift)));
315 
316     hook->destruct(phase);
317 
318     Node* dest_scale = phase->transform(new LShiftXNode(dest_offset, phase->intcon(shift)));
319 
320     adr_src          = phase->transform(new AddPNode(base_src, base_src, src_scale));
321     adr_dest         = phase->transform(new AddPNode(base_dest, base_dest, dest_scale));
322 
323     adr_src          = phase->transform(new AddPNode(base_src, adr_src, phase->MakeConX(header)));
324     adr_dest         = phase->transform(new AddPNode(base_dest, adr_dest, phase->MakeConX(header)));
325 
326     copy_type = dest_elem;
327   } else {
328     assert(ary_src != nullptr, "should be a clone");
329     assert(is_clonebasic(), "should be");
330 
331     disjoint_bases = true;
332 
333     BasicType elem = ary_src->isa_aryptr()->elem()->array_element_basic_type();
334     if (is_reference_type(elem, true)) {
335       elem = T_OBJECT;
336     }
337 
338     BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
339     if (bs->array_copy_requires_gc_barriers(true, elem, true, is_clone_inst(), BarrierSetC2::Optimization)) {
340       return false;
341     }
342 
343     adr_src  = phase->transform(new AddPNode(base_src, base_src, src_offset));
344     adr_dest = phase->transform(new AddPNode(base_dest, base_dest, dest_offset));
345 
346     // The address is offsetted to an aligned address where a raw copy would start.
347     // If the clone copy is decomposed into load-stores - the address is adjusted to
348     // point at where the array starts.
349     const Type* toff = phase->type(src_offset);
350     int offset = toff->isa_long() ? (int) toff->is_long()->get_con() : (int) toff->is_int()->get_con();
351     int diff = arrayOopDesc::base_offset_in_bytes(elem) - offset;
352     assert(diff >= 0, "clone should not start after 1st array element");
353     if (diff > 0) {
354       adr_src = phase->transform(new AddPNode(base_src, adr_src, phase->MakeConX(diff)));
355       adr_dest = phase->transform(new AddPNode(base_dest, adr_dest, phase->MakeConX(diff)));
356     }
357     copy_type = elem;
358     value_type = ary_src->elem();
359   }
360   return true;
361 }
362 
363 const TypePtr* ArrayCopyNode::get_address_type(PhaseGVN* phase, const TypePtr* atp, Node* n) {
364   if (atp == TypeOopPtr::BOTTOM) {
365     atp = phase->type(n)->isa_ptr();
366   }
367   // adjust atp to be the correct array element address type
368   return atp->add_offset(Type::OffsetBot);
369 }
370 
371 void ArrayCopyNode::array_copy_test_overlap(PhaseGVN *phase, bool can_reshape, bool disjoint_bases, int count, Node*& forward_ctl, Node*& backward_ctl) {
372   Node* ctl = in(TypeFunc::Control);
373   if (!disjoint_bases && count > 1) {
374     Node* src_offset = in(ArrayCopyNode::SrcPos);
375     Node* dest_offset = in(ArrayCopyNode::DestPos);
376     assert(src_offset != nullptr && dest_offset != nullptr, "should be");
377     Node* cmp = phase->transform(new CmpINode(src_offset, dest_offset));
378     Node *bol = phase->transform(new BoolNode(cmp, BoolTest::lt));
379     IfNode *iff = new IfNode(ctl, bol, PROB_FAIR, COUNT_UNKNOWN);
380 
381     phase->transform(iff);
382 
383     forward_ctl = phase->transform(new IfFalseNode(iff));
384     backward_ctl = phase->transform(new IfTrueNode(iff));
385   } else {
386     forward_ctl = ctl;
387   }
388 }
389 
390 Node* ArrayCopyNode::array_copy_forward(PhaseGVN *phase,
391                                         bool can_reshape,
392                                         Node*& forward_ctl,
393                                         Node* mem,
394                                         const TypePtr* atp_src,
395                                         const TypePtr* atp_dest,
396                                         Node* adr_src,
397                                         Node* base_src,
398                                         Node* adr_dest,
399                                         Node* base_dest,
400                                         BasicType copy_type,
401                                         const Type* value_type,
402                                         int count) {
403   if (!forward_ctl->is_top()) {
404     // copy forward
405     MergeMemNode* mm = MergeMemNode::make(mem);
406 
407     if (count > 0) {
408       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
409       Node* v = load(bs, phase, forward_ctl, mm, adr_src, atp_src, value_type, copy_type);
410       store(bs, phase, forward_ctl, mm, adr_dest, atp_dest, v, value_type, copy_type);
411       for (int i = 1; i < count; i++) {
412         Node* off  = phase->MakeConX(type2aelembytes(copy_type) * i);
413         Node* next_src = phase->transform(new AddPNode(base_src,adr_src,off));
414         Node* next_dest = phase->transform(new AddPNode(base_dest,adr_dest,off));
415         v = load(bs, phase, forward_ctl, mm, next_src, atp_src, value_type, copy_type);
416         store(bs, phase, forward_ctl, mm, next_dest, atp_dest, v, value_type, copy_type);
417       }
418     } else if (can_reshape) {
419       PhaseIterGVN* igvn = phase->is_IterGVN();
420       igvn->_worklist.push(adr_src);
421       igvn->_worklist.push(adr_dest);
422     }
423     return mm;
424   }
425   return phase->C->top();
426 }
427 
428 Node* ArrayCopyNode::array_copy_backward(PhaseGVN *phase,
429                                          bool can_reshape,
430                                          Node*& backward_ctl,
431                                          Node* mem,
432                                          const TypePtr* atp_src,
433                                          const TypePtr* atp_dest,
434                                          Node* adr_src,
435                                          Node* base_src,
436                                          Node* adr_dest,
437                                          Node* base_dest,
438                                          BasicType copy_type,
439                                          const Type* value_type,
440                                          int count) {
441   if (!backward_ctl->is_top()) {
442     // copy backward
443     MergeMemNode* mm = MergeMemNode::make(mem);
444 
445     BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
446     assert(copy_type != T_OBJECT || !bs->array_copy_requires_gc_barriers(false, T_OBJECT, false, false, BarrierSetC2::Optimization), "only tightly coupled allocations for object arrays");
447 
448     if (count > 0) {
449       for (int i = count-1; i >= 1; i--) {
450         Node* off  = phase->MakeConX(type2aelembytes(copy_type) * i);
451         Node* next_src = phase->transform(new AddPNode(base_src,adr_src,off));
452         Node* next_dest = phase->transform(new AddPNode(base_dest,adr_dest,off));
453         Node* v = load(bs, phase, backward_ctl, mm, next_src, atp_src, value_type, copy_type);
454         store(bs, phase, backward_ctl, mm, next_dest, atp_dest, v, value_type, copy_type);
455       }
456       Node* v = load(bs, phase, backward_ctl, mm, adr_src, atp_src, value_type, copy_type);
457       store(bs, phase, backward_ctl, mm, adr_dest, atp_dest, v, value_type, copy_type);
458     } else if (can_reshape) {
459       PhaseIterGVN* igvn = phase->is_IterGVN();
460       igvn->_worklist.push(adr_src);
461       igvn->_worklist.push(adr_dest);
462     }
463     return phase->transform(mm);
464   }
465   return phase->C->top();
466 }
467 
468 bool ArrayCopyNode::finish_transform(PhaseGVN *phase, bool can_reshape,
469                                      Node* ctl, Node *mem) {
470   if (can_reshape) {
471     PhaseIterGVN* igvn = phase->is_IterGVN();
472     igvn->set_delay_transform(false);
473     if (is_clonebasic()) {
474       Node* out_mem = proj_out(TypeFunc::Memory);
475 
476       BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
477       if (out_mem->outcnt() != 1 || !out_mem->raw_out(0)->is_MergeMem() ||
478           out_mem->raw_out(0)->outcnt() != 1 || !out_mem->raw_out(0)->raw_out(0)->is_MemBar()) {
479         assert(bs->array_copy_requires_gc_barriers(true, T_OBJECT, true, is_clone_inst(), BarrierSetC2::Optimization), "can only happen with card marking");
480         return false;
481       }
482 
483       igvn->replace_node(out_mem->raw_out(0), mem);
484 
485       Node* out_ctl = proj_out(TypeFunc::Control);
486       igvn->replace_node(out_ctl, ctl);
487     } else {
488       // replace fallthrough projections of the ArrayCopyNode by the
489       // new memory, control and the input IO.
490       CallProjections callprojs;
491       extract_projections(&callprojs, true, false);
492 
493       if (callprojs.fallthrough_ioproj != nullptr) {
494         igvn->replace_node(callprojs.fallthrough_ioproj, in(TypeFunc::I_O));
495       }
496       if (callprojs.fallthrough_memproj != nullptr) {
497         igvn->replace_node(callprojs.fallthrough_memproj, mem);
498       }
499       if (callprojs.fallthrough_catchproj != nullptr) {
500         igvn->replace_node(callprojs.fallthrough_catchproj, ctl);
501       }
502 
503       // The ArrayCopyNode is not disconnected. It still has the
504       // projections for the exception case. Replace current
505       // ArrayCopyNode with a dummy new one with a top() control so
506       // that this part of the graph stays consistent but is
507       // eventually removed.
508 
509       set_req(0, phase->C->top());
510       remove_dead_region(phase, can_reshape);
511     }
512   } else {
513     if (in(TypeFunc::Control) != ctl) {
514       // we can't return new memory and control from Ideal at parse time
515       assert(!is_clonebasic() || UseShenandoahGC, "added control for clone?");
516       phase->record_for_igvn(this);
517       return false;
518     }
519   }
520   return true;
521 }
522 
523 
524 Node *ArrayCopyNode::Ideal(PhaseGVN *phase, bool can_reshape) {
525   if (remove_dead_region(phase, can_reshape))  return this;
526 
527   if (StressArrayCopyMacroNode && !can_reshape) {
528     phase->record_for_igvn(this);
529     return nullptr;
530   }
531 
532   // See if it's a small array copy and we can inline it as
533   // loads/stores
534   // Here we can only do:
535   // - arraycopy if all arguments were validated before and we don't
536   // need card marking
537   // - clone for which we don't need to do card marking
538 
539   if (!is_clonebasic() && !is_arraycopy_validated() &&
540       !is_copyofrange_validated() && !is_copyof_validated()) {
541     return nullptr;
542   }
543 
544   assert(in(TypeFunc::Control) != nullptr &&
545          in(TypeFunc::Memory) != nullptr &&
546          in(ArrayCopyNode::Src) != nullptr &&
547          in(ArrayCopyNode::Dest) != nullptr &&
548          in(ArrayCopyNode::Length) != nullptr &&
549          in(ArrayCopyNode::SrcPos) != nullptr &&
550          in(ArrayCopyNode::DestPos) != nullptr, "broken inputs");
551 
552   if (in(TypeFunc::Control)->is_top() ||
553       in(TypeFunc::Memory)->is_top() ||
554       phase->type(in(ArrayCopyNode::Src)) == Type::TOP ||
555       phase->type(in(ArrayCopyNode::Dest)) == Type::TOP ||
556       (in(ArrayCopyNode::SrcPos) != nullptr && in(ArrayCopyNode::SrcPos)->is_top()) ||
557       (in(ArrayCopyNode::DestPos) != nullptr && in(ArrayCopyNode::DestPos)->is_top())) {
558     return nullptr;
559   }
560 
561   int count = get_count(phase);
562 
563   if (count < 0 || count > ArrayCopyLoadStoreMaxElem) {
564     return nullptr;
565   }
566 
567   Node* mem = try_clone_instance(phase, can_reshape, count);
568   if (mem != nullptr) {
569     return (mem == NodeSentinel) ? nullptr : mem;
570   }
571 
572   Node* adr_src = nullptr;
573   Node* base_src = nullptr;
574   Node* adr_dest = nullptr;
575   Node* base_dest = nullptr;
576   BasicType copy_type = T_ILLEGAL;
577   const Type* value_type = nullptr;
578   bool disjoint_bases = false;
579 
580   if (!prepare_array_copy(phase, can_reshape,
581                           adr_src, base_src, adr_dest, base_dest,
582                           copy_type, value_type, disjoint_bases)) {
583     assert(adr_src == nullptr, "no node can be left behind");
584     assert(adr_dest == nullptr, "no node can be left behind");
585     return nullptr;
586   }
587 
588   Node* src = in(ArrayCopyNode::Src);
589   Node* dest = in(ArrayCopyNode::Dest);
590   const TypePtr* atp_src = get_address_type(phase, _src_type, src);
591   const TypePtr* atp_dest = get_address_type(phase, _dest_type, dest);
592   Node* in_mem = in(TypeFunc::Memory);
593 
594   if (can_reshape) {
595     assert(!phase->is_IterGVN()->delay_transform(), "cannot delay transforms");
596     phase->is_IterGVN()->set_delay_transform(true);
597   }
598 
599   Node* backward_ctl = phase->C->top();
600   Node* forward_ctl = phase->C->top();
601   array_copy_test_overlap(phase, can_reshape, disjoint_bases, count, forward_ctl, backward_ctl);
602 
603   Node* forward_mem = array_copy_forward(phase, can_reshape, forward_ctl,
604                                          in_mem,
605                                          atp_src, atp_dest,
606                                          adr_src, base_src, adr_dest, base_dest,
607                                          copy_type, value_type, count);
608 
609   Node* backward_mem = array_copy_backward(phase, can_reshape, backward_ctl,
610                                            in_mem,
611                                            atp_src, atp_dest,
612                                            adr_src, base_src, adr_dest, base_dest,
613                                            copy_type, value_type, count);
614 
615   Node* ctl = nullptr;
616   if (!forward_ctl->is_top() && !backward_ctl->is_top()) {
617     ctl = new RegionNode(3);
618     ctl->init_req(1, forward_ctl);
619     ctl->init_req(2, backward_ctl);
620     ctl = phase->transform(ctl);
621     MergeMemNode* forward_mm = forward_mem->as_MergeMem();
622     MergeMemNode* backward_mm = backward_mem->as_MergeMem();
623     for (MergeMemStream mms(forward_mm, backward_mm); mms.next_non_empty2(); ) {
624       if (mms.memory() != mms.memory2()) {
625         Node* phi = new PhiNode(ctl, Type::MEMORY, phase->C->get_adr_type(mms.alias_idx()));
626         phi->init_req(1, mms.memory());
627         phi->init_req(2, mms.memory2());
628         phi = phase->transform(phi);
629         mms.set_memory(phi);
630       }
631     }
632     mem = forward_mem;
633   } else if (!forward_ctl->is_top()) {
634     ctl = forward_ctl;
635     mem = forward_mem;
636   } else {
637     assert(!backward_ctl->is_top(), "no copy?");
638     ctl = backward_ctl;
639     mem = backward_mem;
640   }
641 
642   if (can_reshape) {
643     assert(phase->is_IterGVN()->delay_transform(), "should be delaying transforms");
644     phase->is_IterGVN()->set_delay_transform(false);
645   }
646 
647   if (!finish_transform(phase, can_reshape, ctl, mem)) {
648     if (can_reshape) {
649       // put in worklist, so that if it happens to be dead it is removed
650       phase->is_IterGVN()->_worklist.push(mem);
651     }
652     return nullptr;
653   }
654 
655   return mem;
656 }
657 
658 bool ArrayCopyNode::may_modify(const TypeOopPtr* t_oop, PhaseValues* phase) {
659   Node* dest = in(ArrayCopyNode::Dest);
660   if (dest->is_top()) {
661     return false;
662   }
663   const TypeOopPtr* dest_t = phase->type(dest)->is_oopptr();
664   assert(!dest_t->is_known_instance() || _dest_type->is_known_instance(), "result of EA not recorded");
665   assert(in(ArrayCopyNode::Src)->is_top() || !phase->type(in(ArrayCopyNode::Src))->is_oopptr()->is_known_instance() ||
666          _src_type->is_known_instance(), "result of EA not recorded");
667 
668   if (_dest_type != TypeOopPtr::BOTTOM || t_oop->is_known_instance()) {
669     assert(_dest_type == TypeOopPtr::BOTTOM || _dest_type->is_known_instance(), "result of EA is known instance");
670     return t_oop->instance_id() == _dest_type->instance_id();
671   }
672 
673   return CallNode::may_modify_arraycopy_helper(dest_t, t_oop, phase);
674 }
675 
676 bool ArrayCopyNode::may_modify_helper(const TypeOopPtr* t_oop, Node* n, PhaseValues* phase, CallNode*& call) {
677   if (n != nullptr &&
678       n->is_Call() &&
679       n->as_Call()->may_modify(t_oop, phase) &&
680       (n->as_Call()->is_ArrayCopy() || n->as_Call()->is_call_to_arraycopystub())) {
681     call = n->as_Call();
682     return true;
683   }
684   return false;
685 }
686 
687 bool ArrayCopyNode::may_modify(const TypeOopPtr* t_oop, MemBarNode* mb, PhaseValues* phase, ArrayCopyNode*& ac) {
688   Node* c = mb->in(0);
689 
690   BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
691   // step over g1 gc barrier if we're at e.g. a clone with ReduceInitialCardMarks off
692   c = bs->step_over_gc_barrier(c);
693 
694   CallNode* call = nullptr;
695   guarantee(c != nullptr, "step_over_gc_barrier failed, there must be something to step to.");
696   if (c->is_Region()) {
697     for (uint i = 1; i < c->req(); i++) {
698       if (c->in(i) != nullptr) {
699         Node* n = c->in(i)->in(0);
700         if (may_modify_helper(t_oop, n, phase, call)) {
701           ac = call->isa_ArrayCopy();
702           assert(c == mb->in(0), "only for clone");
703           return true;
704         }
705       }
706     }
707   } else if (may_modify_helper(t_oop, c->in(0), phase, call)) {
708     ac = call->isa_ArrayCopy();
709 #ifdef ASSERT
710     bool use_ReduceInitialCardMarks = BarrierSet::barrier_set()->is_a(BarrierSet::CardTableBarrierSet) &&
711       static_cast<CardTableBarrierSetC2*>(bs)->use_ReduceInitialCardMarks();
712     assert(c == mb->in(0) || (ac != nullptr && ac->is_clonebasic() && !use_ReduceInitialCardMarks), "only for clone");
713 #endif
714     return true;
715   } else if (mb->trailing_partial_array_copy()) {
716     return true;
717   }
718 
719   return false;
720 }
721 
722 // Does this array copy modify offsets between offset_lo and offset_hi
723 // in the destination array
724 // if must_modify is false, return true if the copy could write
725 // between offset_lo and offset_hi
726 // if must_modify is true, return true if the copy is guaranteed to
727 // write between offset_lo and offset_hi
728 bool ArrayCopyNode::modifies(intptr_t offset_lo, intptr_t offset_hi, PhaseValues* phase, bool must_modify) const {
729   assert(_kind == ArrayCopy || _kind == CopyOf || _kind == CopyOfRange, "only for real array copies");
730 
731   Node* dest = in(Dest);
732   Node* dest_pos = in(DestPos);
733   Node* len = in(Length);
734 
735   const TypeInt *dest_pos_t = phase->type(dest_pos)->isa_int();
736   const TypeInt *len_t = phase->type(len)->isa_int();
737   const TypeAryPtr* ary_t = phase->type(dest)->isa_aryptr();
738 
739   if (dest_pos_t == nullptr || len_t == nullptr || ary_t == nullptr) {
740     return !must_modify;
741   }
742 
743   BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
744   if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
745 
746   uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
747   uint elemsize = type2aelembytes(ary_elem);
748 
749   jlong dest_pos_plus_len_lo = (((jlong)dest_pos_t->_lo) + len_t->_lo) * elemsize + header;
750   jlong dest_pos_plus_len_hi = (((jlong)dest_pos_t->_hi) + len_t->_hi) * elemsize + header;
751   jlong dest_pos_lo = ((jlong)dest_pos_t->_lo) * elemsize + header;
752   jlong dest_pos_hi = ((jlong)dest_pos_t->_hi) * elemsize + header;
753 
754   if (must_modify) {
755     if (offset_lo >= dest_pos_hi && offset_hi < dest_pos_plus_len_lo) {
756       return true;
757     }
758   } else {
759     if (offset_hi >= dest_pos_lo && offset_lo < dest_pos_plus_len_hi) {
760       return true;
761     }
762   }
763   return false;
764 }
765 
766 // As an optimization, choose optimum vector size for copy length known at compile time.
767 int ArrayCopyNode::get_partial_inline_vector_lane_count(BasicType type, int const_len) {
768   int lane_count = ArrayOperationPartialInlineSize/type2aelembytes(type);
769   if (const_len > 0) {
770     int size_in_bytes = const_len * type2aelembytes(type);
771     if (size_in_bytes <= 16)
772       lane_count = 16/type2aelembytes(type);
773     else if (size_in_bytes > 16 && size_in_bytes <= 32)
774       lane_count = 32/type2aelembytes(type);
775   }
776   return lane_count;
777 }