1 /*
2 * Copyright (c) 1997, 2026, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2024, Alibaba Group Holding Limited. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #include "ci/ciFlatArrayKlass.hpp"
27 #include "ci/ciInlineKlass.hpp"
28 #include "classfile/javaClasses.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmIntrinsics.hpp"
31 #include "compiler/compileLog.hpp"
32 #include "gc/shared/barrierSet.hpp"
33 #include "gc/shared/c2/barrierSetC2.hpp"
34 #include "gc/shared/tlab_globals.hpp"
35 #include "memory/allocation.inline.hpp"
36 #include "memory/resourceArea.hpp"
37 #include "oops/flatArrayKlass.hpp"
38 #include "oops/objArrayKlass.hpp"
39 #include "opto/addnode.hpp"
40 #include "opto/arraycopynode.hpp"
41 #include "opto/callnode.hpp"
42 #include "opto/cfgnode.hpp"
43 #include "opto/compile.hpp"
44 #include "opto/connode.hpp"
45 #include "opto/convertnode.hpp"
46 #include "opto/inlinetypenode.hpp"
47 #include "opto/loopnode.hpp"
48 #include "opto/machnode.hpp"
49 #include "opto/matcher.hpp"
50 #include "opto/memnode.hpp"
51 #include "opto/mempointer.hpp"
52 #include "opto/mulnode.hpp"
53 #include "opto/narrowptrnode.hpp"
54 #include "opto/opcodes.hpp"
55 #include "opto/phaseX.hpp"
56 #include "opto/regalloc.hpp"
57 #include "opto/regmask.hpp"
58 #include "opto/rootnode.hpp"
59 #include "opto/traceMergeStoresTag.hpp"
60 #include "opto/vectornode.hpp"
61 #include "runtime/arguments.hpp"
62 #include "utilities/align.hpp"
63 #include "utilities/copy.hpp"
64 #include "utilities/globalDefinitions.hpp"
65 #include "utilities/macros.hpp"
66 #include "utilities/powerOfTwo.hpp"
67 #include "utilities/vmError.hpp"
68
69 // Portions of code courtesy of Clifford Click
70
71 // Optimization - Graph Style
72
73 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
74
75 //=============================================================================
76 uint MemNode::size_of() const { return sizeof(*this); }
77
78 const TypePtr *MemNode::adr_type() const {
79 Node* adr = in(Address);
80 if (adr == nullptr) return nullptr; // node is dead
81 const TypePtr* cross_check = nullptr;
82 DEBUG_ONLY(cross_check = _adr_type);
83 return calculate_adr_type(adr->bottom_type(), cross_check);
84 }
85
86 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
87 if (adr != nullptr) {
88 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
89 return true;
90 }
91 }
92 return false;
93 }
94
95 #ifndef PRODUCT
96 void MemNode::dump_spec(outputStream *st) const {
97 if (in(Address) == nullptr) return; // node is dead
98 #ifndef ASSERT
99 // fake the missing field
100 const TypePtr* _adr_type = nullptr;
101 if (in(Address) != nullptr)
102 _adr_type = in(Address)->bottom_type()->isa_ptr();
103 #endif
104 dump_adr_type(_adr_type, st);
105
106 Compile* C = Compile::current();
107 if (C->alias_type(_adr_type)->is_volatile()) {
108 st->print(" Volatile!");
109 }
110 if (_unaligned_access) {
111 st->print(" unaligned");
112 }
113 if (_mismatched_access) {
114 st->print(" mismatched");
115 }
116 if (_unsafe_access) {
117 st->print(" unsafe");
118 }
119 }
120
121 void MemNode::dump_adr_type(const TypePtr* adr_type, outputStream* st) {
122 st->print(" @");
123 if (adr_type == nullptr) {
124 st->print("null");
125 } else {
126 adr_type->dump_on(st);
127 Compile* C = Compile::current();
128 Compile::AliasType* atp = nullptr;
129 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
130 if (atp == nullptr)
131 st->print(", idx=?\?;");
132 else if (atp->index() == Compile::AliasIdxBot)
133 st->print(", idx=Bot;");
134 else if (atp->index() == Compile::AliasIdxTop)
135 st->print(", idx=Top;");
136 else if (atp->index() == Compile::AliasIdxRaw)
137 st->print(", idx=Raw;");
138 else {
139 ciField* field = atp->field();
140 if (field) {
141 st->print(", name=");
142 field->print_name_on(st);
143 }
144 st->print(", idx=%d;", atp->index());
145 }
146 }
147 }
148
149 extern void print_alias_types();
150
151 #endif
152
153 // Find the memory output corresponding to the fall-through path of a call
154 static Node* find_call_fallthrough_mem_output(CallNode* call) {
155 ResourceMark rm;
156 CallProjections* projs = call->extract_projections(false, false);
157 Node* res = projs->fallthrough_memproj;
158 assert(res != nullptr, "must have a fallthrough mem output");
159 return res;
160 }
161
162 // Try to find a better memory input for a load from a strict final field
163 static Node* try_optimize_strict_final_load_memory(PhaseGVN* phase, Node* adr, ProjNode*& base_local) {
164 intptr_t offset = 0;
165 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
166 if (base == nullptr) {
167 return nullptr;
168 }
169
170 Node* base_uncasted = base->uncast();
171 if (base_uncasted->is_Proj()) {
172 Node* multi = base_uncasted->in(0);
173 if (multi->is_top()) {
174 // The pointer dies, make the memory die, too
175 return multi;
176 } else if (multi->is_Allocate()) {
177 base_local = base_uncasted->as_Proj();
178 return nullptr;
179 } else if (multi->is_Call()) {
180 if (!multi->is_CallJava() || multi->as_CallJava()->method() == nullptr || !multi->as_CallJava()->method()->return_value_is_larval()) {
181 // The oop is returned from a call, the memory can be the fallthrough output of the call
182 return find_call_fallthrough_mem_output(multi->as_Call());
183 }
184 } else if (multi->is_Start()) {
185 // The oop is a parameter
186 if (base_uncasted->as_Proj()->_con == TypeFunc::Parms && phase->C->method()->receiver_maybe_larval()) {
187 // The receiver of a constructor is similar to the result of an AllocateNode
188 base_local = base_uncasted->as_Proj();
189 return nullptr;
190 } else {
191 // Use the start memory otherwise
192 return multi->as_Start()->proj_out(TypeFunc::Memory);
193 }
194 }
195 }
196
197 return nullptr;
198 }
199
200 // Whether a call can modify a strict final field, given that the object is allocated inside the
201 // current compilation unit, or is the first parameter when the compilation root is a constructor.
202 // This is equivalent to asking whether 'call' is a constructor invocation and the class declaring
203 // the target method is a subclass of the class declaring 'field'.
204 static bool call_can_modify_local_object(ciField* field, CallNode* call) {
205 if (!call->is_CallJava()) {
206 return false;
207 }
208
209 ciMethod* target = call->as_CallJava()->method();
210 if (target == nullptr) {
211 return false;
212 } else if (target->intrinsic_id() == vmIntrinsicID::_linkToSpecial) {
213 // linkToSpecial can be used to call a constructor, used in the construction of objects in the
214 // reflection API
215 return true;
216 } else if (!target->is_object_constructor()) {
217 return false;
218 }
219
220 // If 'field' is declared in a class that is a subclass of the one declaring the constructor,
221 // then the field is set inside the constructor, else the field must be set before the
222 // constructor invocation. E.g. A field Super.x will be set during the execution of Sub::<init>,
223 // while a field Sub.y must be set before Super::<init> is invoked.
224 // We can try to be more heroic and decide if the receiver of the constructor invocation is the
225 // object from which we are loading from. This, however, may be problematic as deciding if 2
226 // nodes are definitely different may not be trivial, especially if the graph is not canonical.
227 // As a result, it is made more conservative for now.
228 assert(call->req() > TypeFunc::Parms, "constructor must have at least 1 argument");
229 return target->holder()->is_subclass_of(field->holder());
230 }
231
232 Node* MemNode::optimize_simple_memory_chain(Node* mchain, const TypeOopPtr* t_oop, Node* load, PhaseGVN* phase) {
233 assert(t_oop != nullptr, "sanity");
234 bool is_known_instance = t_oop->is_known_instance_field();
235 bool is_strict_final_load = false;
236
237 // After macro expansion, an allocation may become a call, changing the memory input to the
238 // memory output of that call would be illegal. As a result, disallow this transformation after
239 // macro expansion.
240 if (phase->is_IterGVN() && phase->C->allow_macro_nodes() && load != nullptr && load->is_Load() && !load->as_Load()->is_mismatched_access()) {
241 is_strict_final_load = t_oop->is_ptr_to_strict_final_field();
242 #ifdef ASSERT
243 if ((t_oop->is_inlinetypeptr() && t_oop->inline_klass()->contains_field_offset(t_oop->offset())) || t_oop->is_ptr_to_boxed_value()) {
244 assert(is_strict_final_load, "sanity check for basic cases");
245 }
246 #endif // ASSERT
247 }
248
249 if (!is_known_instance && !is_strict_final_load) {
250 return mchain;
251 }
252
253 Node* result = mchain;
254 ProjNode* base_local = nullptr;
255
256 ciField* field = nullptr;
257 if (is_strict_final_load) {
258 field = phase->C->alias_type(t_oop)->field();
259 assert(field != nullptr, "must point to a field");
260
261 Node* adr = load->in(MemNode::Address);
262 assert(phase->type(adr) == t_oop, "inconsistent type");
263 Node* tmp = try_optimize_strict_final_load_memory(phase, adr, base_local);
264 if (tmp != nullptr) {
265 result = tmp;
266 }
267 }
268
269 uint instance_id = t_oop->instance_id();
270 Node* start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
271 Node* prev = nullptr;
272 while (prev != result) {
273 prev = result;
274 if (result == start_mem) {
275 // start_mem is the earliest memory possible
276 break;
277 }
278
279 // skip over a call which does not affect this memory slice
280 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
281 Node* proj_in = result->in(0);
282 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
283 // This is the allocation that creates the object from which we are loading from
284 break;
285 } else if (proj_in->is_Call()) {
286 // ArrayCopyNodes processed here as well
287 CallNode* call = proj_in->as_Call();
288 if (!call->may_modify(t_oop, phase)) {
289 result = call->in(TypeFunc::Memory);
290 } else if (is_strict_final_load && base_local != nullptr && !call_can_modify_local_object(field, call)) {
291 result = call->in(TypeFunc::Memory);
292 }
293 } else if (proj_in->Opcode() == Op_Tuple) {
294 // The call will be folded, skip over it.
295 break;
296 } else if (proj_in->is_Initialize()) {
297 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
298 // Stop if this is the initialization for the object instance which
299 // contains this memory slice, otherwise skip over it.
300 if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
301 break;
302 }
303 if (is_known_instance) {
304 result = proj_in->in(TypeFunc::Memory);
305 } else if (is_strict_final_load) {
306 Node* klass = alloc->in(AllocateNode::KlassNode);
307 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
308 if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
309 // Allocation of another type, must be another object
310 result = proj_in->in(TypeFunc::Memory);
311 } else if (base_local != nullptr && (base_local->is_Parm() || base_local->in(0) != alloc)) {
312 // Allocation of another object
313 result = proj_in->in(TypeFunc::Memory);
314 }
315 }
316 } else if (proj_in->is_MemBar()) {
317 ArrayCopyNode* ac = nullptr;
318 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
319 break;
320 }
321 result = proj_in->in(TypeFunc::Memory);
322 } else if (proj_in->is_LoadFlat() || proj_in->is_StoreFlat()) {
323 if (is_strict_final_load) {
324 // LoadFlat and StoreFlat cannot happen to strict final fields
325 result = proj_in->in(TypeFunc::Memory);
326 }
327 } else if (proj_in->is_top()) {
328 break; // dead code
329 } else {
330 assert(false, "unexpected projection of %s", proj_in->Name());
331 }
332 } else if (result->is_ClearArray()) {
333 if (!is_known_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
334 // Can not bypass initialization of the instance
335 // we are looking for.
336 break;
337 }
338 // Otherwise skip it (the call updated 'result' value).
339 } else if (result->is_MergeMem()) {
340 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
341 }
342 }
343 return result;
344 }
345
346 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
347 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
348 if (t_oop == nullptr)
349 return mchain; // don't try to optimize non-oop types
350 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
351 bool is_instance = t_oop->is_known_instance_field();
352 PhaseIterGVN *igvn = phase->is_IterGVN();
353 if (is_instance && igvn != nullptr && result->is_Phi()) {
354 PhiNode *mphi = result->as_Phi();
355 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
356 const TypePtr *t = mphi->adr_type();
357 bool do_split = false;
358 // In the following cases, Load memory input can be further optimized based on
359 // its precise address type
360 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
361 do_split = true;
362 } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
363 const TypeOopPtr* mem_t =
364 t->is_oopptr()->cast_to_exactness(true)
365 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
366 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
367 if (t_oop->isa_aryptr()) {
368 mem_t = mem_t->is_aryptr()
369 ->cast_to_stable(t_oop->is_aryptr()->is_stable())
370 ->cast_to_size(t_oop->is_aryptr()->size())
371 ->cast_to_not_flat(t_oop->is_aryptr()->is_not_flat())
372 ->cast_to_not_null_free(t_oop->is_aryptr()->is_not_null_free())
373 ->with_offset(t_oop->is_aryptr()->offset())
374 ->is_aryptr();
375 }
376 do_split = mem_t == t_oop;
377 }
378 if (do_split) {
379 // clone the Phi with our address type
380 result = mphi->split_out_instance(t_adr, igvn);
381 } else {
382 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
383 }
384 }
385 return result;
386 }
387
388 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
389 uint alias_idx = phase->C->get_alias_index(tp);
390 Node *mem = mmem;
391 #ifdef ASSERT
392 {
393 // Check that current type is consistent with the alias index used during graph construction
394 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
395 bool consistent = adr_check == nullptr || adr_check->empty() ||
396 phase->C->must_alias(adr_check, alias_idx );
397 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
398 if( !consistent && adr_check != nullptr && !adr_check->empty() &&
399 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
400 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
401 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
402 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
403 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
404 // don't assert if it is dead code.
405 consistent = true;
406 }
407 if( !consistent ) {
408 st->print("alias_idx==%d, adr_check==", alias_idx);
409 if( adr_check == nullptr ) {
410 st->print("null");
411 } else {
412 adr_check->dump();
413 }
414 st->cr();
415 print_alias_types();
416 assert(consistent, "adr_check must match alias idx");
417 }
418 }
419 #endif
420 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
421 // means an array I have not precisely typed yet. Do not do any
422 // alias stuff with it any time soon.
423 const TypeOopPtr *toop = tp->isa_oopptr();
424 if (tp->base() != Type::AnyPtr &&
425 !(toop &&
426 toop->isa_instptr() &&
427 toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
428 toop->offset() == Type::OffsetBot)) {
429 // IGVN _delay_transform may be set to true and if that is the case and mmem
430 // is already a registered node then the validation inside transform will
431 // complain.
432 Node* m = mmem;
433 PhaseIterGVN* igvn = phase->is_IterGVN();
434 if (igvn == nullptr || !igvn->delay_transform()) {
435 // compress paths and change unreachable cycles to TOP
436 // If not, we can update the input infinitely along a MergeMem cycle
437 // Equivalent code in PhiNode::Ideal
438 m = phase->transform(mmem);
439 }
440 // If transformed to a MergeMem, get the desired slice
441 // Otherwise the returned node represents memory for every slice
442 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
443 // Update input if it is progress over what we have now
444 }
445 return mem;
446 }
447
448 //--------------------------Ideal_common---------------------------------------
449 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
450 // Unhook non-raw memories from complete (macro-expanded) initializations.
451 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
452 // If our control input is a dead region, kill all below the region
453 Node *ctl = in(MemNode::Control);
454 if (ctl && remove_dead_region(phase, can_reshape))
455 return this;
456 ctl = in(MemNode::Control);
457 // Don't bother trying to transform a dead node
458 if (ctl && ctl->is_top()) return NodeSentinel;
459
460 PhaseIterGVN *igvn = phase->is_IterGVN();
461 // Wait if control on the worklist.
462 if (ctl && can_reshape && igvn != nullptr) {
463 Node* bol = nullptr;
464 Node* cmp = nullptr;
465 if (ctl->in(0)->is_If()) {
466 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
467 bol = ctl->in(0)->in(1);
468 if (bol->is_Bool())
469 cmp = ctl->in(0)->in(1)->in(1);
470 }
471 if (igvn->_worklist.member(ctl) ||
472 (bol != nullptr && igvn->_worklist.member(bol)) ||
473 (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
474 // This control path may be dead.
475 // Delay this memory node transformation until the control is processed.
476 igvn->_worklist.push(this);
477 return NodeSentinel; // caller will return null
478 }
479 }
480 // Ignore if memory is dead, or self-loop
481 Node *mem = in(MemNode::Memory);
482 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
483 assert(mem != this, "dead loop in MemNode::Ideal");
484
485 if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
486 // This memory slice may be dead.
487 // Delay this mem node transformation until the memory is processed.
488 igvn->_worklist.push(this);
489 return NodeSentinel; // caller will return null
490 }
491
492 Node *address = in(MemNode::Address);
493 const Type *t_adr = phase->type(address);
494 if (t_adr == Type::TOP) return NodeSentinel; // caller will return null
495
496 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
497 // Unsafe off-heap access with zero address. Remove access and other control users
498 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
499 assert(ctl != nullptr, "unsafe accesses should be control dependent");
500 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
501 Node* u = ctl->fast_out(i);
502 if (u != ctl) {
503 igvn->rehash_node_delayed(u);
504 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
505 --i, imax -= nb;
506 }
507 }
508 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
509 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
510 phase->C->root()->add_req(halt);
511 return this;
512 }
513
514 if (can_reshape && igvn != nullptr &&
515 (igvn->_worklist.member(address) ||
516 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
517 // The address's base and type may change when the address is processed.
518 // Delay this mem node transformation until the address is processed.
519 igvn->_worklist.push(this);
520 return NodeSentinel; // caller will return null
521 }
522
523 // Do NOT remove or optimize the next lines: ensure a new alias index
524 // is allocated for an oop pointer type before Escape Analysis.
525 // Note: C++ will not remove it since the call has side effect.
526 if (t_adr->isa_oopptr()) {
527 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
528 }
529
530 Node* base = nullptr;
531 if (address->is_AddP()) {
532 base = address->in(AddPNode::Base);
533 }
534 if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
535 !t_adr->isa_rawptr()) {
536 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
537 // Skip this node optimization if its address has TOP base.
538 return NodeSentinel; // caller will return null
539 }
540
541 // Avoid independent memory operations
542 Node* old_mem = mem;
543
544 // The code which unhooks non-raw memories from complete (macro-expanded)
545 // initializations was removed. After macro-expansion all stores caught
546 // by Initialize node became raw stores and there is no information
547 // which memory slices they modify. So it is unsafe to move any memory
548 // operation above these stores. Also in most cases hooked non-raw memories
549 // were already unhooked by using information from detect_ptr_independence()
550 // and find_previous_store().
551
552 if (mem->is_MergeMem()) {
553 MergeMemNode* mmem = mem->as_MergeMem();
554 const TypePtr *tp = t_adr->is_ptr();
555
556 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
557 }
558
559 if (mem != old_mem) {
560 set_req_X(MemNode::Memory, mem, phase);
561 if (phase->type(mem) == Type::TOP) return NodeSentinel;
562 return this;
563 }
564
565 // let the subclass continue analyzing...
566 return nullptr;
567 }
568
569 // Helper function for proving some simple control dominations.
570 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
571 // Already assumes that 'dom' is available at 'sub', and that 'sub'
572 // is not a constant (dominated by the method's StartNode).
573 // Used by MemNode::find_previous_store to prove that the
574 // control input of a memory operation predates (dominates)
575 // an allocation it wants to look past.
576 // Returns 'DomResult::Dominate' if all control inputs of 'dom'
577 // dominate 'sub', 'DomResult::NotDominate' if not,
578 // and 'DomResult::EncounteredDeadCode' if we can't decide due to
579 // dead code, but at the end of IGVN, we know the definite result
580 // once the dead code is cleaned up.
581 Node::DomResult MemNode::maybe_all_controls_dominate(Node* dom, Node* sub, PhaseGVN* phase) {
582 if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top()) {
583 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
584 }
585
586 // Check 'dom'. Skip Proj and CatchProj nodes.
587 dom = dom->find_exact_control(dom);
588 if (dom == nullptr || dom->is_top()) {
589 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
590 }
591
592 if (dom == sub) {
593 // For the case when, for example, 'sub' is Initialize and the original
594 // 'dom' is Proj node of the 'sub'.
595 return DomResult::NotDominate;
596 }
597
598 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) {
599 return DomResult::Dominate;
600 }
601
602 // 'dom' dominates 'sub' if its control edge and control edges
603 // of all its inputs dominate or equal to sub's control edge.
604
605 // Currently 'sub' is either Allocate, Initialize or Start nodes.
606 // Or Region for the check in LoadNode::Ideal();
607 // 'sub' should have sub->in(0) != nullptr.
608 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
609 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
610
611 // Get control edge of 'sub'.
612 Node* orig_sub = sub;
613 sub = sub->find_exact_control(sub->in(0));
614 if (sub == nullptr || sub->is_top()) {
615 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
616 }
617
618 assert(sub->is_CFG(), "expecting control");
619
620 if (sub == dom) {
621 return DomResult::Dominate;
622 }
623
624 if (sub->is_Start() || sub->is_Root()) {
625 return DomResult::NotDominate;
626 }
627
628 {
629 // Check all control edges of 'dom'.
630
631 ResourceMark rm;
632 Node_List nlist;
633 Unique_Node_List dom_list;
634
635 dom_list.push(dom);
636 bool only_dominating_controls = false;
637
638 for (uint next = 0; next < dom_list.size(); next++) {
639 Node* n = dom_list.at(next);
640 if (n == orig_sub) {
641 return DomResult::NotDominate; // One of dom's inputs dominated by sub.
642 }
643 if (!n->is_CFG() && n->pinned()) {
644 // Check only own control edge for pinned non-control nodes.
645 n = n->find_exact_control(n->in(0));
646 if (n == nullptr || n->is_top()) {
647 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
648 }
649 assert(n->is_CFG(), "expecting control");
650 dom_list.push(n);
651 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
652 only_dominating_controls = true;
653 } else if (n->is_CFG()) {
654 DomResult dom_result = n->dominates(sub, nlist);
655 if (dom_result == DomResult::Dominate) {
656 only_dominating_controls = true;
657 } else {
658 return dom_result;
659 }
660 } else {
661 if (n->Value(phase) == Type::TOP) {
662 return DomResult::EncounteredDeadCode;
663 }
664 // First, own control edge.
665 Node* m = n->find_exact_control(n->in(0));
666 if (m != nullptr) {
667 if (m->is_top()) {
668 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
669 }
670 dom_list.push(m);
671 }
672 // Now, the rest of edges.
673 uint cnt = n->req();
674 for (uint i = 1; i < cnt; i++) {
675 m = n->find_exact_control(n->in(i));
676 if (m == nullptr || m->is_top()) {
677 continue;
678 }
679 dom_list.push(m);
680 }
681 }
682 }
683 return only_dominating_controls ? DomResult::Dominate : DomResult::NotDominate;
684 }
685 }
686
687 //---------------------detect_ptr_independence---------------------------------
688 // Used by MemNode::find_previous_store to prove that two base
689 // pointers are never equal.
690 // The pointers are accompanied by their associated allocations,
691 // if any, which have been previously discovered by the caller.
692 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
693 Node* p2, AllocateNode* a2,
694 PhaseGVN* phase) {
695 // Trivial case: Non-overlapping values. Be careful, we can cast a raw pointer to an oop (e.g. in
696 // the allocation pattern) so joining the types only works if both are oops. join may also give
697 // an incorrect result when both pointers are nullable and the result is supposed to be
698 // TypePtr::NULL_PTR, so we exclude that case.
699 const Type* p1_type = p1->bottom_type();
700 const Type* p2_type = p2->bottom_type();
701 if (p1_type->isa_oopptr() && p2_type->isa_oopptr() &&
702 (!p1_type->maybe_null() || !p2_type->maybe_null()) &&
703 p1_type->join(p2_type)->empty()) {
704 return true;
705 }
706
707 // Attempt to prove that these two pointers cannot be aliased.
708 // They may both manifestly be allocations, and they should differ.
709 // Or, if they are not both allocations, they can be distinct constants.
710 // Otherwise, one is an allocation and the other a pre-existing value.
711 if (a1 == nullptr && a2 == nullptr) { // neither an allocation
712 return (p1 != p2) && p1->is_Con() && p2->is_Con();
713 } else if (a1 != nullptr && a2 != nullptr) { // both allocations
714 return (a1 != a2);
715 } else if (a1 != nullptr) { // one allocation a1
716 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
717 return all_controls_dominate(p2, a1, phase);
718 } else { //(a2 != null) // one allocation a2
719 return all_controls_dominate(p1, a2, phase);
720 }
721 return false;
722 }
723
724 // Find an arraycopy ac that produces the memory state represented by parameter mem.
725 // Return ac if
726 // (a) can_see_stored_value=true and ac must have set the value for this load or if
727 // (b) can_see_stored_value=false and ac could have set the value for this load or if
728 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
729 // In case (c) change the parameter mem to the memory input of ac to skip it
730 // when searching stored value.
731 // Otherwise return null.
732 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
733 ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
734 if (ac != nullptr) {
735 Node* ld_addp = in(MemNode::Address);
736 Node* src = ac->in(ArrayCopyNode::Src);
737 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
738
739 // This is a load from a cloned array. The corresponding arraycopy ac must
740 // have set the value for the load and we can return ac but only if the load
741 // is known to be within bounds. This is checked below.
742 if (ary_t != nullptr && ld_addp->is_AddP()) {
743 Node* ld_offs = ld_addp->in(AddPNode::Offset);
744 BasicType ary_elem = ary_t->elem()->array_element_basic_type();
745 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
746 jlong elemsize = type2aelembytes(ary_elem);
747
748 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
749 const TypeInt* sizetype = ary_t->size();
750
751 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
752 // The load is known to be within bounds. It receives its value from ac.
753 return ac;
754 }
755 // The load is known to be out-of-bounds.
756 }
757 // The load could be out-of-bounds. It must not be hoisted but must remain
758 // dependent on the runtime range check. This is achieved by returning null.
759 } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
760 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
761
762 if (ac->is_arraycopy_validated() ||
763 ac->is_copyof_validated() ||
764 ac->is_copyofrange_validated()) {
765 Node* ld_addp = in(MemNode::Address);
766 if (ld_addp->is_AddP()) {
767 Node* ld_base = ld_addp->in(AddPNode::Address);
768 Node* ld_offs = ld_addp->in(AddPNode::Offset);
769
770 Node* dest = ac->in(ArrayCopyNode::Dest);
771
772 if (dest == ld_base) {
773 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
774 assert(!ld_offs_t->empty(), "dead reference should be checked already");
775 // Take into account vector or unsafe access size
776 jlong ld_size_in_bytes = (jlong)memory_size();
777 jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
778 offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
779 if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
780 return ac;
781 }
782 if (!can_see_stored_value) {
783 mem = ac->in(TypeFunc::Memory);
784 return ac;
785 }
786 }
787 }
788 }
789 }
790 return nullptr;
791 }
792
793 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
794 if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
795 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
796 if (ld_alloc != nullptr) {
797 // Check if there is an array copy for a clone
798 Node* mb = mem->in(0);
799 ArrayCopyNode* ac = nullptr;
800 if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
801 mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
802 ac = mb->in(0)->in(0)->as_ArrayCopy();
803 } else {
804 // Step over GC barrier when ReduceInitialCardMarks is disabled
805 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
806 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
807
808 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
809 ac = control_proj_ac->in(0)->as_ArrayCopy();
810 }
811 }
812
813 if (ac != nullptr && ac->is_clonebasic()) {
814 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
815 if (alloc != nullptr && alloc == ld_alloc) {
816 return ac;
817 }
818 }
819 }
820 }
821 return nullptr;
822 }
823
824 // The logic for reordering loads and stores uses four steps:
825 // (a) Walk carefully past stores and initializations which we
826 // can prove are independent of this load.
827 // (b) Observe that the next memory state makes an exact match
828 // with self (load or store), and locate the relevant store.
829 // (c) Ensure that, if we were to wire self directly to the store,
830 // the optimizer would fold it up somehow.
831 // (d) Do the rewiring, and return, depending on some other part of
832 // the optimizer to fold up the load.
833 // This routine handles steps (a) and (b). Steps (c) and (d) are
834 // specific to loads and stores, so they are handled by the callers.
835 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
836 //
837 Node* MemNode::find_previous_store(PhaseGVN* phase) {
838 AccessAnalyzer analyzer(phase, this);
839
840 Node* mem = in(MemNode::Memory); // start searching here...
841 int cnt = 50; // Cycle limiter
842 for (;; cnt--) {
843 // While we can dance past unrelated stores...
844 if (phase->type(mem) == Type::TOP) {
845 // Encounter a dead node
846 return phase->C->top();
847 } else if (cnt <= 0) {
848 // Caught in cycle or a complicated dance?
849 return nullptr;
850 } else if (mem->is_Phi()) {
851 return nullptr;
852 }
853
854 AccessAnalyzer::AccessIndependence independence = analyzer.detect_access_independence(mem);
855 if (independence.independent) {
856 // (a) advance through the independent store
857 mem = independence.mem;
858 assert(mem != nullptr, "must not be nullptr");
859 } else {
860 // (b) found the store that this access observes if this is not null
861 // Otherwise, give up if it is null
862 return independence.mem;
863 }
864 }
865
866 return nullptr; // bail out
867 }
868
869 //----------------------calculate_adr_type-------------------------------------
870 // Helper function. Notices when the given type of address hits top or bottom.
871 // Also, asserts a cross-check of the type against the expected address type.
872 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
873 if (t == Type::TOP) return nullptr; // does not touch memory any more?
874 #ifdef ASSERT
875 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = nullptr;
876 #endif
877 const TypePtr* tp = t->isa_ptr();
878 if (tp == nullptr) {
879 assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
880 return TypePtr::BOTTOM; // touches lots of memory
881 } else {
882 #ifdef ASSERT
883 // %%%% [phh] We don't check the alias index if cross_check is
884 // TypeRawPtr::BOTTOM. Needs to be investigated.
885 if (cross_check != nullptr &&
886 cross_check != TypePtr::BOTTOM &&
887 cross_check != TypeRawPtr::BOTTOM) {
888 // Recheck the alias index, to see if it has changed (due to a bug).
889 Compile* C = Compile::current();
890 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
891 "must stay in the original alias category");
892 // The type of the address must be contained in the adr_type,
893 // disregarding "null"-ness.
894 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
895 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
896 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
897 "real address must not escape from expected memory type");
898 }
899 #endif
900 return tp;
901 }
902 }
903
904 uint8_t MemNode::barrier_data(const Node* n) {
905 if (n->is_LoadStore()) {
906 return n->as_LoadStore()->barrier_data();
907 } else if (n->is_Mem()) {
908 return n->as_Mem()->barrier_data();
909 }
910 return 0;
911 }
912
913 AccessAnalyzer::AccessAnalyzer(PhaseGVN* phase, MemNode* n)
914 : _phase(phase), _n(n), _memory_size(n->memory_size()), _alias_idx(-1) {
915 Node* adr = _n->in(MemNode::Address);
916 _offset = 0;
917 _base = AddPNode::Ideal_base_and_offset(adr, _phase, _offset);
918 _maybe_raw = MemNode::check_if_adr_maybe_raw(adr);
919 _alloc = AllocateNode::Ideal_allocation(_base);
920 _adr_type = _n->adr_type();
921
922 if (_adr_type != nullptr && _adr_type->base() != TypePtr::AnyPtr) {
923 // Avoid the cases that will upset Compile::get_alias_index
924 _alias_idx = _phase->C->get_alias_index(_adr_type);
925 assert(_alias_idx != Compile::AliasIdxTop, "must not be a dead node");
926 assert(_alias_idx != Compile::AliasIdxBot || !phase->C->do_aliasing(), "must not be a very wide access");
927 }
928 }
929
930 // Decide whether the memory accessed by '_n' and 'other' may overlap. This function may be used
931 // when we want to walk the memory graph to fold a load, or when we want to hoist a load above a
932 // loop when there are no stores that may overlap with the load inside the loop.
933 AccessAnalyzer::AccessIndependence AccessAnalyzer::detect_access_independence(Node* other) const {
934 assert(_phase->type(other) == Type::MEMORY, "must be a memory node %s", other->Name());
935 assert(!other->is_Phi(), "caller must handle Phi");
936
937 if (_adr_type == nullptr) {
938 // This means the access is dead
939 return {false, _phase->C->top()};
940 } else if (_adr_type->base() == TypePtr::AnyPtr) {
941 // An example for this case is an access into the memory address 0 performed using Unsafe
942 assert(_adr_type->ptr() == TypePtr::Null, "MemNode should never access a wide memory");
943 return {false, nullptr};
944 }
945
946 if (_offset == Type::OffsetBot) {
947 // cannot unalias unless there are precise offsets
948 return {false, nullptr};
949 }
950
951 const TypeOopPtr* adr_oop_type = _adr_type->isa_oopptr();
952 Node* prev = other;
953 if (other->is_Store()) {
954 Node* st_adr = other->in(MemNode::Address);
955 intptr_t st_offset = 0;
956 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, _phase, st_offset);
957 if (st_base == nullptr) {
958 // inscrutable pointer
959 return {false, nullptr};
960 }
961
962 // If the bases are the same and the offsets are the same, it seems that this is the exact
963 // store we are looking for, the caller will check if the type of the store matches using
964 // MemNode::can_see_stored_value
965 if (st_base == _base && st_offset == _offset) {
966 return {false, other};
967 }
968
969 // If it is provable that the memory accessed by 'other' does not overlap the memory accessed
970 // by '_n', we may walk past 'other'.
971 // For raw accesses, 2 accesses are independent if they have the same base and the offsets
972 // say that they do not overlap.
973 // For heap accesses, 2 accesses are independent if either the bases are provably different
974 // at runtime or the offsets say that the accesses do not overlap.
975 if ((_maybe_raw || MemNode::check_if_adr_maybe_raw(st_adr)) && st_base != _base) {
976 // Raw accesses can only be provably independent if they have the same base
977 return {false, nullptr};
978 }
979
980 // If the offsets say that the accesses do not overlap, then it is provable that 'other' and
981 // '_n' do not overlap. For example, a LoadI from Object+8 is independent from a StoreL into
982 // Object+12, no matter what the bases are.
983 if (st_offset != _offset && st_offset != Type::OffsetBot) {
984 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
985 assert(other->as_Store()->memory_size() <= MAX_STORE, "");
986 if (st_offset >= _offset + _memory_size ||
987 st_offset <= _offset - MAX_STORE ||
988 st_offset <= _offset - other->as_Store()->memory_size()) {
989 // Success: The offsets are provably independent.
990 // (You may ask, why not just test st_offset != offset and be done?
991 // The answer is that stores of different sizes can co-exist
992 // in the same sequence of RawMem effects. We sometimes initialize
993 // a whole 'tile' of array elements with a single jint or jlong.)
994 return {true, other->in(MemNode::Memory)};
995 }
996 }
997
998 // Same base and overlapping offsets, it seems provable that the accesses overlap, give up
999 if (st_base == _base) {
1000 return {false, nullptr};
1001 }
1002
1003 // Try to prove that 2 different base nodes at compile time are different values at runtime
1004 bool known_independent = false;
1005 if (MemNode::detect_ptr_independence(_base, _alloc, st_base, AllocateNode::Ideal_allocation(st_base), _phase)) {
1006 known_independent = true;
1007 }
1008
1009 if (known_independent) {
1010 return {true, other->in(MemNode::Memory)};
1011 }
1012 } else if (other->is_Proj() && other->in(0)->is_Initialize()) {
1013 InitializeNode* st_init = other->in(0)->as_Initialize();
1014 AllocateNode* st_alloc = st_init->allocation();
1015 if (st_alloc == nullptr) {
1016 // Something degenerated
1017 return {false, nullptr};
1018 }
1019 bool known_identical = false;
1020 bool known_independent = false;
1021 if (_alloc == st_alloc) {
1022 known_identical = true;
1023 } else if (_alloc != nullptr) {
1024 known_independent = true;
1025 } else if (MemNode::all_controls_dominate(_n, st_alloc, _phase)) {
1026 known_independent = true;
1027 }
1028
1029 if (known_independent) {
1030 // The bases are provably independent: Either they are
1031 // manifestly distinct allocations, or else the control
1032 // of _n dominates the store's allocation.
1033 if (_alias_idx == Compile::AliasIdxRaw) {
1034 other = st_alloc->in(TypeFunc::Memory);
1035 } else {
1036 other = st_init->memory(_alias_idx);
1037 }
1038 return {true, other};
1039 }
1040
1041 // If we are not looking at a store initializing the same
1042 // allocation we are loading from, we lose.
1043 if (known_identical) {
1044 // From caller, can_see_stored_value will consult find_captured_store.
1045 return {false, other};
1046 }
1047
1048 } else if (_n->find_previous_arraycopy(_phase, _alloc, other, false) != nullptr) {
1049 // Find an arraycopy that may or may not affect the MemNode
1050 return {prev != other, other};
1051 } else if (other->is_MergeMem()) {
1052 return {true, other->as_MergeMem()->memory_at(_alias_idx)};
1053 } else if (adr_oop_type != nullptr && adr_oop_type->is_known_instance_field()) {
1054 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
1055 if (other->is_Proj() && other->in(0)->is_Call()) {
1056 // ArrayCopyNodes processed here as well.
1057 CallNode* call = other->in(0)->as_Call();
1058 if (!call->may_modify(adr_oop_type, _phase)) {
1059 return {true, call->in(TypeFunc::Memory)};
1060 }
1061 } else if (other->is_Proj() && other->in(0)->is_MemBar()) {
1062 ArrayCopyNode* ac = nullptr;
1063 if (!ArrayCopyNode::may_modify(adr_oop_type, other->in(0)->as_MemBar(), _phase, ac)) {
1064 return {true, other->in(0)->in(TypeFunc::Memory)};
1065 }
1066 } else if (other->is_ClearArray()) {
1067 if (ClearArrayNode::step_through(&other, (uint)adr_oop_type->instance_id(), _phase)) {
1068 // (the call updated 'other' value)
1069 return {true, other};
1070 } else {
1071 // Can not bypass initialization of the instance
1072 // we are looking for.
1073 return {false, other};
1074 }
1075 }
1076 }
1077
1078 return {false, nullptr};
1079 }
1080
1081 //=============================================================================
1082 // Should LoadNode::Ideal() attempt to remove control edges?
1083 bool LoadNode::can_remove_control() const {
1084 return !has_pinned_control_dependency();
1085 }
1086 uint LoadNode::size_of() const { return sizeof(*this); }
1087 bool LoadNode::cmp(const Node &n) const {
1088 LoadNode& load = (LoadNode &)n;
1089 return Type::equals(_type, load._type) &&
1090 _control_dependency == load._control_dependency &&
1091 _mo == load._mo;
1092 }
1093 const Type *LoadNode::bottom_type() const { return _type; }
1094 uint LoadNode::ideal_reg() const {
1095 return _type->ideal_reg();
1096 }
1097
1098 #ifndef PRODUCT
1099 void LoadNode::dump_spec(outputStream *st) const {
1100 MemNode::dump_spec(st);
1101 if( !Verbose && !WizardMode ) {
1102 // standard dump does this in Verbose and WizardMode
1103 st->print(" #"); _type->dump_on(st);
1104 }
1105 if (in(0) != nullptr && !depends_only_on_test()) {
1106 st->print(" (does not depend only on test, ");
1107 if (control_dependency() == UnknownControl) {
1108 st->print("unknown control");
1109 } else if (control_dependency() == Pinned) {
1110 st->print("pinned");
1111 } else if (adr_type() == TypeRawPtr::BOTTOM) {
1112 st->print("raw access");
1113 } else {
1114 st->print("unknown reason");
1115 }
1116 st->print(")");
1117 }
1118 }
1119 #endif
1120
1121 #ifdef ASSERT
1122 //----------------------------is_immutable_value-------------------------------
1123 // Helper function to allow a raw load without control edge for some cases
1124 bool LoadNode::is_immutable_value(Node* adr) {
1125 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
1126 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
1127
1128 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
1129 int offsets[] = {
1130 in_bytes(JavaThread::osthread_offset()),
1131 in_bytes(JavaThread::threadObj_offset()),
1132 in_bytes(JavaThread::vthread_offset()),
1133 in_bytes(JavaThread::scopedValueCache_offset()),
1134 };
1135
1136 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
1137 if (offset == offsets[i]) {
1138 return true;
1139 }
1140 }
1141 }
1142
1143 return false;
1144 }
1145 #endif
1146
1147 //----------------------------LoadNode::make-----------------------------------
1148 // Polymorphic factory method:
1149 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
1150 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
1151 Compile* C = gvn.C;
1152 assert(adr->is_top() || C->get_alias_index(gvn.type(adr)->is_ptr(), true) == C->get_alias_index(adr_type, true), "adr and adr_type must agree");
1153
1154 // sanity check the alias category against the created node type
1155 assert(!(adr_type->isa_oopptr() &&
1156 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
1157 "use LoadKlassNode instead");
1158 assert(!(adr_type->isa_aryptr() &&
1159 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
1160 "use LoadRangeNode instead");
1161 // Check control edge of raw loads
1162 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
1163 // oop will be recorded in oop map if load crosses safepoint
1164 rt->isa_oopptr() || is_immutable_value(adr),
1165 "raw memory operations should have control edge");
1166 LoadNode* load = nullptr;
1167 switch (bt) {
1168 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1169 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1170 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1171 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1172 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1173 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
1174 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
1175 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
1176 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
1177 case T_ARRAY:
1178 case T_OBJECT:
1179 case T_NARROWOOP:
1180 #ifdef _LP64
1181 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1182 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
1183 } else
1184 #endif
1185 {
1186 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
1187 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
1188 }
1189 break;
1190 default:
1191 guarantee(false, "unexpected basic type %s", type2name(bt));
1192 break;
1193 }
1194 assert(load != nullptr, "LoadNode should have been created");
1195 if (unaligned) {
1196 load->set_unaligned_access();
1197 }
1198 if (mismatched) {
1199 load->set_mismatched_access();
1200 }
1201 if (unsafe) {
1202 load->set_unsafe_access();
1203 }
1204 load->set_barrier_data(barrier_data);
1205 if (load->Opcode() == Op_LoadN) {
1206 Node* ld = gvn.transform(load);
1207 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
1208 }
1209
1210 return load;
1211 }
1212
1213 //------------------------------hash-------------------------------------------
1214 uint LoadNode::hash() const {
1215 // unroll addition of interesting fields
1216 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
1217 }
1218
1219 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
1220 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
1221 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
1222 bool is_stable_ary = FoldStableValues &&
1223 (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
1224 tp->isa_aryptr()->is_stable();
1225
1226 return (eliminate_boxing && non_volatile) || is_stable_ary || tp->is_inlinetypeptr();
1227 }
1228
1229 return false;
1230 }
1231
1232 // Is the value loaded previously stored by an arraycopy? If so return
1233 // a load node that reads from the source array so we may be able to
1234 // optimize out the ArrayCopy node later.
1235 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1236 Node* ld_adr = in(MemNode::Address);
1237 intptr_t ld_off = 0;
1238 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1239 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1240 if (ac != nullptr) {
1241 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1242
1243 Node* mem = ac->in(TypeFunc::Memory);
1244 Node* ctl = ac->in(0);
1245 Node* src = ac->in(ArrayCopyNode::Src);
1246
1247 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1248 return nullptr;
1249 }
1250
1251 // load depends on the tests that validate the arraycopy
1252 LoadNode* ld = clone_pinned();
1253 Node* addp = in(MemNode::Address)->clone();
1254 if (ac->as_ArrayCopy()->is_clonebasic()) {
1255 assert(ld_alloc != nullptr, "need an alloc");
1256 assert(addp->is_AddP(), "address must be addp");
1257 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1258 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1259 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1260 addp->set_req(AddPNode::Base, src);
1261 addp->set_req(AddPNode::Address, src);
1262 } else {
1263 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1264 ac->as_ArrayCopy()->is_copyof_validated() ||
1265 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1266 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1267 addp->set_req(AddPNode::Base, src);
1268 addp->set_req(AddPNode::Address, src);
1269
1270 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1271 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1272 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1273
1274 uint shift = ary_t->is_flat() ? ary_t->flat_log_elem_size() : exact_log2(type2aelembytes(ary_elem));
1275
1276 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1277 #ifdef _LP64
1278 diff = phase->transform(new ConvI2LNode(diff));
1279 #endif
1280 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1281
1282 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1283 addp->set_req(AddPNode::Offset, offset);
1284 }
1285 addp = phase->transform(addp);
1286 #ifdef ASSERT
1287 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1288 ld->_adr_type = adr_type;
1289 #endif
1290 ld->set_req(MemNode::Address, addp);
1291 ld->set_req(0, ctl);
1292 ld->set_req(MemNode::Memory, mem);
1293 return ld;
1294 }
1295 return nullptr;
1296 }
1297
1298 static Node* see_through_inline_type(PhaseValues* phase, const MemNode* load, Node* base, int offset) {
1299 if (!load->is_mismatched_access() && base != nullptr && base->is_InlineType() && offset > oopDesc::klass_offset_in_bytes()) {
1300 InlineTypeNode* vt = base->as_InlineType();
1301 Node* value = vt->field_value_by_offset(offset, true);
1302 assert(value != nullptr, "must see some value");
1303 return value;
1304 }
1305
1306 return nullptr;
1307 }
1308
1309 // This routine exists to make sure this set of tests is done the same
1310 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1311 // will change the graph shape in a way which makes memory alive twice at the
1312 // same time (uses the Oracle model of aliasing), then some
1313 // LoadXNode::Identity will fold things back to the equivalence-class model
1314 // of aliasing.
1315 // This method may find an unencoded node instead of the corresponding encoded one.
1316 Node* LoadNode::can_see_stored_value_through_membars(Node* st, PhaseValues* phase) const {
1317 Node* ld_adr = in(MemNode::Address);
1318 intptr_t ld_off = 0;
1319 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1320 // Try to see through an InlineTypeNode
1321 // LoadN is special because the input is not compressed
1322 if (Opcode() != Op_LoadN) {
1323 Node* value = see_through_inline_type(phase, this, ld_base, ld_off);
1324 if (value != nullptr) {
1325 return value;
1326 }
1327 }
1328
1329 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1330 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1331
1332 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1333 uint alias_idx = atp->index();
1334 Node* result = nullptr;
1335 Node* current = st;
1336 // Skip through chains of MemBarNodes checking the MergeMems for new states for the slice of
1337 // this load. Stop once any other kind of node is encountered.
1338 //
1339 // In principle, folding a load is moving it up until it meets a matching store.
1340 //
1341 // store(ptr, v); store(ptr, v); store(ptr, v);
1342 // membar1; -> membar1; -> load(ptr);
1343 // membar2; load(ptr); membar1;
1344 // load(ptr); membar2; membar2;
1345 //
1346 // So, we can decide which kinds of barriers we can walk past. It is not safe to step over
1347 // MemBarCPUOrder, even if the memory is not rewritable, because alias info above them may be
1348 // inaccurate (e.g., due to mixed/mismatched unsafe accesses).
1349 bool is_final_mem = !atp->is_rewritable();
1350 while (current->is_Proj()) {
1351 int opc = current->in(0)->Opcode();
1352 if ((is_final_mem && (opc == Op_MemBarAcquire || opc == Op_MemBarAcquireLock || opc == Op_LoadFence)) ||
1353 opc == Op_MemBarRelease ||
1354 opc == Op_StoreFence ||
1355 opc == Op_MemBarReleaseLock ||
1356 opc == Op_MemBarStoreStore ||
1357 opc == Op_StoreStoreFence) {
1358 Node* mem = current->in(0)->in(TypeFunc::Memory);
1359 if (mem->is_MergeMem()) {
1360 MergeMemNode* merge = mem->as_MergeMem();
1361 Node* new_st = merge->memory_at(alias_idx);
1362 if (new_st == merge->base_memory()) {
1363 // Keep searching
1364 current = new_st;
1365 continue;
1366 }
1367 // Save the new memory state for the slice and fall through
1368 // to exit.
1369 result = new_st;
1370 }
1371 }
1372 break;
1373 }
1374 if (result != nullptr) {
1375 st = result;
1376 }
1377 }
1378
1379 return can_see_stored_value(st, phase);
1380 }
1381
1382 // If st is a store to the same location as this, return the stored value
1383 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1384 Node* ld_adr = in(MemNode::Address);
1385 intptr_t ld_off = 0;
1386 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1387 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1388 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1389
1390 // Loop around twice in the case Load -> Initialize -> Store.
1391 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1392 for (int trip = 0; trip <= 1; trip++) {
1393
1394 if (st->is_Store()) {
1395 Node* st_adr = st->in(MemNode::Address);
1396 if (st_adr != ld_adr) {
1397 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1398 intptr_t st_off = 0;
1399 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1400 if (ld_base == nullptr) return nullptr;
1401 if (st_base == nullptr) return nullptr;
1402 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1403 if (ld_off != st_off) return nullptr;
1404 if (ld_off == Type::OffsetBot) return nullptr;
1405 // Same base, same offset.
1406 // Possible improvement for arrays: check index value instead of absolute offset.
1407
1408 // At this point we have proven something like this setup:
1409 // B = << base >>
1410 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1411 // S = StoreQ(AddP( B , #Off), V)
1412 // (Actually, we haven't yet proven the Q's are the same.)
1413 // In other words, we are loading from a casted version of
1414 // the same pointer-and-offset that we stored to.
1415 // Casted version may carry a dependency and it is respected.
1416 // Thus, we are able to replace L by V.
1417 }
1418 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1419 if (store_Opcode() != st->Opcode()) {
1420 return nullptr;
1421 }
1422 // LoadVector/StoreVector needs additional check to ensure the types match.
1423 if (st->is_StoreVector()) {
1424 if ((Opcode() != Op_LoadVector && Opcode() != Op_StoreVector) || st->Opcode() != Op_StoreVector) {
1425 // Some kind of masked access or gather/scatter
1426 return nullptr;
1427 }
1428
1429 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1430 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1431 if (in_vt != out_vt) {
1432 return nullptr;
1433 }
1434 }
1435 return st->in(MemNode::ValueIn);
1436 }
1437
1438 // A load from a freshly-created object always returns zero.
1439 // (This can happen after LoadNode::Ideal resets the load's memory input
1440 // to find_captured_store, which returned InitializeNode::zero_memory.)
1441 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1442 (st->in(0) == ld_alloc) &&
1443 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1444 // return a zero value for the load's basic type
1445 // (This is one of the few places where a generic PhaseTransform
1446 // can create new nodes. Think of it as lazily manifesting
1447 // virtually pre-existing constants.)
1448 Node* init_value = ld_alloc->in(AllocateNode::InitValue);
1449 if (init_value != nullptr) {
1450 const TypeAryPtr* ld_adr_type = phase->type(ld_adr)->isa_aryptr();
1451 if (ld_adr_type == nullptr) {
1452 return nullptr;
1453 }
1454
1455 // We know that this is not a flat array, the load should return the whole oop
1456 if (ld_adr_type->is_not_flat()) {
1457 return init_value;
1458 }
1459
1460 // If this is a flat array, try to see through init_value
1461 if (init_value->is_EncodeP()) {
1462 init_value = init_value->in(1);
1463 }
1464 if (!init_value->is_InlineType() || ld_adr_type->field_offset() == Type::Offset::bottom) {
1465 return nullptr;
1466 }
1467
1468 ciInlineKlass* vk = phase->type(init_value)->inline_klass();
1469 int field_offset_in_payload = ld_adr_type->field_offset().get();
1470 if (field_offset_in_payload == vk->null_marker_offset_in_payload()) {
1471 return init_value->as_InlineType()->get_null_marker();
1472 } else {
1473 return init_value->as_InlineType()->field_value_by_offset(field_offset_in_payload + vk->payload_offset(), true);
1474 }
1475 }
1476 assert(ld_alloc->in(AllocateNode::RawInitValue) == nullptr, "init value may not be null");
1477 if (value_basic_type() != T_VOID) {
1478 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1479 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1480 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1481 // by the ArrayCopyNode.
1482 return phase->zerocon(value_basic_type());
1483 }
1484 } else {
1485 // TODO: materialize all-zero vector constant
1486 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1487 }
1488 }
1489
1490 // A load from an initialization barrier can match a captured store.
1491 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1492 InitializeNode* init = st->in(0)->as_Initialize();
1493 AllocateNode* alloc = init->allocation();
1494 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1495 // examine a captured store value
1496 st = init->find_captured_store(ld_off, memory_size(), phase);
1497 if (st != nullptr) {
1498 continue; // take one more trip around
1499 }
1500 }
1501 }
1502
1503 // Load boxed value from result of valueOf() call is input parameter.
1504 if (this->is_Load() && ld_adr->is_AddP() &&
1505 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1506 intptr_t ignore = 0;
1507 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1508 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1509 base = bs->step_over_gc_barrier(base);
1510 if (base != nullptr && base->is_Proj() &&
1511 base->as_Proj()->_con == TypeFunc::Parms &&
1512 base->in(0)->is_CallStaticJava() &&
1513 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1514 return base->in(0)->in(TypeFunc::Parms);
1515 }
1516 }
1517
1518 break;
1519 }
1520
1521 return nullptr;
1522 }
1523
1524 //----------------------is_instance_field_load_with_local_phi------------------
1525 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1526 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1527 in(Address)->is_AddP() ) {
1528 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1529 // Only known instances and immutable fields
1530 if( t_oop != nullptr &&
1531 (t_oop->is_ptr_to_strict_final_field() ||
1532 t_oop->is_known_instance_field()) &&
1533 t_oop->offset() != Type::OffsetBot &&
1534 t_oop->offset() != Type::OffsetTop) {
1535 return true;
1536 }
1537 }
1538 return false;
1539 }
1540
1541 //------------------------------Identity---------------------------------------
1542 // Loads are identity if previous store is to same address
1543 Node* LoadNode::Identity(PhaseGVN* phase) {
1544 // If the previous store-maker is the right kind of Store, and the store is
1545 // to the same address, then we are equal to the value stored.
1546 Node* mem = in(Memory);
1547 Node* value = can_see_stored_value_through_membars(mem, phase);
1548 if( value ) {
1549 // byte, short & char stores truncate naturally.
1550 // A load has to load the truncated value which requires
1551 // some sort of masking operation and that requires an
1552 // Ideal call instead of an Identity call.
1553 if (memory_size() < BytesPerInt) {
1554 // If the input to the store does not fit with the load's result type,
1555 // it must be truncated via an Ideal call.
1556 if (!phase->type(value)->higher_equal(phase->type(this)))
1557 return this;
1558 }
1559
1560 if (phase->type(value)->isa_ptr() && phase->type(this)->isa_narrowoop()) {
1561 return this;
1562 }
1563 // (This works even when value is a Con, but LoadNode::Value
1564 // usually runs first, producing the singleton type of the Con.)
1565 if (!has_pinned_control_dependency() || value->is_Con()) {
1566 return value;
1567 } else {
1568 return this;
1569 }
1570 }
1571
1572 if (has_pinned_control_dependency()) {
1573 return this;
1574 }
1575 // Search for an existing data phi which was generated before for the same
1576 // instance's field to avoid infinite generation of phis in a loop.
1577 Node *region = mem->in(0);
1578 if (is_instance_field_load_with_local_phi(region)) {
1579 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1580 int this_index = phase->C->get_alias_index(addr_t);
1581 int this_offset = addr_t->offset();
1582 int this_iid = addr_t->instance_id();
1583 if (!addr_t->is_known_instance() &&
1584 addr_t->is_ptr_to_strict_final_field()) {
1585 // Use _idx of address base (could be Phi node) for immutable fields in unknown instances
1586 intptr_t ignore = 0;
1587 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1588 if (base == nullptr) {
1589 return this;
1590 }
1591 this_iid = base->_idx;
1592 }
1593 const Type* this_type = bottom_type();
1594 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1595 Node* phi = region->fast_out(i);
1596 if (phi->is_Phi() && phi != mem &&
1597 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1598 return phi;
1599 }
1600 }
1601 }
1602
1603 return this;
1604 }
1605
1606 // Construct an equivalent unsigned load.
1607 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1608 BasicType bt = T_ILLEGAL;
1609 const Type* rt = nullptr;
1610 switch (Opcode()) {
1611 case Op_LoadUB: return this;
1612 case Op_LoadUS: return this;
1613 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1614 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1615 default:
1616 assert(false, "no unsigned variant: %s", Name());
1617 return nullptr;
1618 }
1619 const Type* mem_t = gvn.type(in(MemNode::Address));
1620 if (mem_t == Type::TOP) {
1621 return gvn.C->top();
1622 }
1623 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1624 mem_t->is_ptr(), rt, bt, _mo, _control_dependency,
1625 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1626 }
1627
1628 // Construct an equivalent signed load.
1629 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1630 BasicType bt = T_ILLEGAL;
1631 const Type* rt = nullptr;
1632 switch (Opcode()) {
1633 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1634 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1635 case Op_LoadB: // fall through
1636 case Op_LoadS: // fall through
1637 case Op_LoadI: // fall through
1638 case Op_LoadL: return this;
1639 default:
1640 assert(false, "no signed variant: %s", Name());
1641 return nullptr;
1642 }
1643 const Type* mem_t = gvn.type(in(MemNode::Address));
1644 if (mem_t == Type::TOP) {
1645 return gvn.C->top();
1646 }
1647 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1648 mem_t->is_ptr(), rt, bt, _mo, _control_dependency,
1649 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1650 }
1651
1652 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1653 BasicType bt = rt->basic_type();
1654 switch (Opcode()) {
1655 case Op_LoadI: return (bt == T_FLOAT);
1656 case Op_LoadL: return (bt == T_DOUBLE);
1657 case Op_LoadF: return (bt == T_INT);
1658 case Op_LoadD: return (bt == T_LONG);
1659
1660 default: return false;
1661 }
1662 }
1663
1664 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1665 BasicType bt = rt->basic_type();
1666 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1667 bool is_mismatched = is_mismatched_access();
1668 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1669 if (raw_type == nullptr) {
1670 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1671 }
1672 const int op = Opcode();
1673 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1674 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1675 const Type* mem_t = gvn.type(in(MemNode::Address));
1676 if (mem_t == Type::TOP) {
1677 return gvn.C->top();
1678 }
1679 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1680 mem_t->is_ptr(), rt, bt, _mo, _control_dependency,
1681 require_atomic_access, is_unaligned_access(), is_mismatched);
1682 }
1683
1684 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1685 BasicType bt = vt->basic_type();
1686 switch (Opcode()) {
1687 case Op_StoreI: return (bt == T_FLOAT);
1688 case Op_StoreL: return (bt == T_DOUBLE);
1689 case Op_StoreF: return (bt == T_INT);
1690 case Op_StoreD: return (bt == T_LONG);
1691
1692 default: return false;
1693 }
1694 }
1695
1696 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1697 BasicType bt = vt->basic_type();
1698 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1699 const int op = Opcode();
1700 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1701 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1702 const Type* mem_t = gvn.type(in(MemNode::Address));
1703 if (mem_t == Type::TOP) {
1704 return gvn.C->top();
1705 }
1706 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1707 mem_t->is_ptr(), val, bt, _mo, require_atomic_access);
1708
1709 bool is_mismatched = is_mismatched_access();
1710 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1711 if (raw_type == nullptr) {
1712 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1713 }
1714 if (is_mismatched) {
1715 st->set_mismatched_access();
1716 }
1717 return st;
1718 }
1719
1720 // We're loading from an object which has autobox behaviour.
1721 // If this object is result of a valueOf call we'll have a phi
1722 // merging a newly allocated object and a load from the cache.
1723 // We want to replace this load with the original incoming
1724 // argument to the valueOf call.
1725 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1726 assert(igvn->C->eliminate_boxing(), "sanity");
1727 intptr_t ignore = 0;
1728 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1729 if ((base == nullptr) || base->is_Phi()) {
1730 // Push the loads from the phi that comes from valueOf up
1731 // through it to allow elimination of the loads and the recovery
1732 // of the original value. It is done in split_through_phi().
1733 return nullptr;
1734 } else if (base->is_Load() ||
1735 (base->is_DecodeN() && base->in(1)->is_Load())) {
1736 // Eliminate the load of boxed value for integer types from the cache
1737 // array by deriving the value from the index into the array.
1738 // Capture the offset of the load and then reverse the computation.
1739
1740 // Get LoadN node which loads a boxing object from 'cache' array.
1741 if (base->is_DecodeN()) {
1742 base = base->in(1);
1743 }
1744 if (!base->in(Address)->is_AddP()) {
1745 return nullptr; // Complex address
1746 }
1747 AddPNode* address = base->in(Address)->as_AddP();
1748 Node* cache_base = address->in(AddPNode::Base);
1749 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1750 // Get ConP node which is static 'cache' field.
1751 cache_base = cache_base->in(1);
1752 }
1753 if ((cache_base != nullptr) && cache_base->is_Con()) {
1754 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1755 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1756 Node* elements[4];
1757 int shift = exact_log2(type2aelembytes(T_OBJECT));
1758 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1759 if (count > 0 && elements[0]->is_Con() &&
1760 (count == 1 ||
1761 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1762 elements[1]->in(2) == igvn->intcon(shift)))) {
1763 ciObjArray* array = base_type->const_oop()->as_obj_array();
1764 // Fetch the box object cache[0] at the base of the array and get its value
1765 ciInstance* box = array->obj_at(0)->as_instance();
1766 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1767 assert(ik->is_box_klass(), "sanity");
1768 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1769 if (ik->nof_nonstatic_fields() == 1) {
1770 // This should be true nonstatic_field_at requires calling
1771 // nof_nonstatic_fields so check it anyway
1772 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1773 BasicType bt = c.basic_type();
1774 // Only integer types have boxing cache.
1775 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1776 bt == T_BYTE || bt == T_SHORT ||
1777 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1778 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1779 if (cache_low != (int)cache_low) {
1780 return nullptr; // should not happen since cache is array indexed by value
1781 }
1782 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1783 if (offset != (int)offset) {
1784 return nullptr; // should not happen since cache is array indexed by value
1785 }
1786 // Add up all the offsets making of the address of the load
1787 Node* result = elements[0];
1788 for (int i = 1; i < count; i++) {
1789 result = igvn->transform(new AddXNode(result, elements[i]));
1790 }
1791 // Remove the constant offset from the address and then
1792 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1793 // remove the scaling of the offset to recover the original index.
1794 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1795 // Peel the shift off directly but wrap it in a dummy node
1796 // since Ideal can't return existing nodes
1797 igvn->_worklist.push(result); // remove dead node later
1798 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1799 } else if (result->is_Add() && result->in(2)->is_Con() &&
1800 result->in(1)->Opcode() == Op_LShiftX &&
1801 result->in(1)->in(2) == igvn->intcon(shift)) {
1802 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1803 // but for boxing cache access we know that X<<Z will not overflow
1804 // (there is range check) so we do this optimizatrion by hand here.
1805 igvn->_worklist.push(result); // remove dead node later
1806 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1807 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1808 } else {
1809 result = new RShiftXNode(result, igvn->intcon(shift));
1810 }
1811 #ifdef _LP64
1812 if (bt != T_LONG) {
1813 result = new ConvL2INode(igvn->transform(result));
1814 }
1815 #else
1816 if (bt == T_LONG) {
1817 result = new ConvI2LNode(igvn->transform(result));
1818 }
1819 #endif
1820 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1821 // Need to preserve unboxing load type if it is unsigned.
1822 switch(this->Opcode()) {
1823 case Op_LoadUB:
1824 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1825 break;
1826 case Op_LoadUS:
1827 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1828 break;
1829 }
1830 return result;
1831 }
1832 }
1833 }
1834 }
1835 }
1836 return nullptr;
1837 }
1838
1839 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1840 Node* region = phi->in(0);
1841 if (region == nullptr) {
1842 return false; // Wait stable graph
1843 }
1844 uint cnt = phi->req();
1845 for (uint i = 1; i < cnt; i++) {
1846 Node* rc = region->in(i);
1847 if (rc == nullptr || phase->type(rc) == Type::TOP)
1848 return false; // Wait stable graph
1849 Node* in = phi->in(i);
1850 if (in == nullptr || phase->type(in) == Type::TOP)
1851 return false; // Wait stable graph
1852 }
1853 return true;
1854 }
1855
1856 //------------------------------split_through_phi------------------------------
1857 // Check whether a call to 'split_through_phi' would split this load through the
1858 // Phi *base*. This method is essentially a copy of the validations performed
1859 // by 'split_through_phi'. The first use of this method was in EA code as part
1860 // of simplification of allocation merges.
1861 // Some differences from original method (split_through_phi):
1862 // - If base->is_CastPP(): base = base->in(1)
1863 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1864 Node* mem = in(Memory);
1865 Node* address = in(Address);
1866 intptr_t ignore = 0;
1867 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1868
1869 if (base == nullptr) {
1870 return false;
1871 }
1872
1873 if (base->is_CastPP()) {
1874 base = base->in(1);
1875 }
1876
1877 if (req() > 3 || !base->is_Phi()) {
1878 return false;
1879 }
1880
1881 if (!mem->is_Phi()) {
1882 if (!MemNode::all_controls_dominate(mem, base->in(0), phase)) {
1883 return false;
1884 }
1885 } else if (base->in(0) != mem->in(0)) {
1886 if (!MemNode::all_controls_dominate(mem, base->in(0), phase)) {
1887 return false;
1888 }
1889 }
1890
1891 return true;
1892 }
1893
1894 //------------------------------split_through_phi------------------------------
1895 // Split instance or boxed field load through Phi.
1896 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1897 if (req() > 3) {
1898 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1899 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1900 return nullptr;
1901 }
1902 Node* mem = in(Memory);
1903 Node* address = in(Address);
1904 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1905
1906 assert((t_oop != nullptr) &&
1907 (ignore_missing_instance_id ||
1908 t_oop->is_known_instance_field() ||
1909 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1910
1911 Compile* C = phase->C;
1912 intptr_t ignore = 0;
1913 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1914 bool base_is_phi = (base != nullptr) && base->is_Phi();
1915 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1916 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1917 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1918
1919 if (!((mem->is_Phi() || base_is_phi) &&
1920 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1921 return nullptr; // Neither memory or base are Phi
1922 }
1923
1924 if (mem->is_Phi()) {
1925 if (!stable_phi(mem->as_Phi(), phase)) {
1926 return nullptr; // Wait stable graph
1927 }
1928 uint cnt = mem->req();
1929 // Check for loop invariant memory.
1930 if (cnt == 3) {
1931 for (uint i = 1; i < cnt; i++) {
1932 Node* in = mem->in(i);
1933 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1934 if (m == mem) {
1935 if (i == 1) {
1936 // if the first edge was a loop, check second edge too.
1937 // If both are replaceable - we are in an infinite loop
1938 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1939 if (n == mem) {
1940 break;
1941 }
1942 }
1943 set_req(Memory, mem->in(cnt - i));
1944 return this; // made change
1945 }
1946 }
1947 }
1948 }
1949 if (base_is_phi) {
1950 if (!stable_phi(base->as_Phi(), phase)) {
1951 return nullptr; // Wait stable graph
1952 }
1953 uint cnt = base->req();
1954 // Check for loop invariant memory.
1955 if (cnt == 3) {
1956 for (uint i = 1; i < cnt; i++) {
1957 if (base->in(i) == base) {
1958 return nullptr; // Wait stable graph
1959 }
1960 }
1961 }
1962 }
1963
1964 // Split through Phi (see original code in loopopts.cpp).
1965 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1966
1967 // Do nothing here if Identity will find a value
1968 // (to avoid infinite chain of value phis generation).
1969 if (this != Identity(phase)) {
1970 return nullptr;
1971 }
1972
1973 // Select Region to split through.
1974 Node* region;
1975 DomResult dom_result = DomResult::Dominate;
1976 if (!base_is_phi) {
1977 assert(mem->is_Phi(), "sanity");
1978 region = mem->in(0);
1979 // Skip if the region dominates some control edge of the address.
1980 // We will check `dom_result` later.
1981 dom_result = MemNode::maybe_all_controls_dominate(address, region, phase);
1982 } else if (!mem->is_Phi()) {
1983 assert(base_is_phi, "sanity");
1984 region = base->in(0);
1985 // Skip if the region dominates some control edge of the memory.
1986 // We will check `dom_result` later.
1987 dom_result = MemNode::maybe_all_controls_dominate(mem, region, phase);
1988 } else if (base->in(0) != mem->in(0)) {
1989 assert(base_is_phi && mem->is_Phi(), "sanity");
1990 dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0), phase);
1991 if (dom_result == DomResult::Dominate) {
1992 region = base->in(0);
1993 } else {
1994 dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0), phase);
1995 if (dom_result == DomResult::Dominate) {
1996 region = mem->in(0);
1997 }
1998 // Otherwise we encountered a complex graph.
1999 }
2000 } else {
2001 assert(base->in(0) == mem->in(0), "sanity");
2002 region = mem->in(0);
2003 }
2004
2005 PhaseIterGVN* igvn = phase->is_IterGVN();
2006 if (dom_result != DomResult::Dominate) {
2007 if (dom_result == DomResult::EncounteredDeadCode) {
2008 // There is some dead code which eventually will be removed in IGVN.
2009 // Once this is the case, we get an unambiguous dominance result.
2010 // Push the node to the worklist again until the dead code is removed.
2011 igvn->_worklist.push(this);
2012 }
2013 return nullptr;
2014 }
2015
2016 Node* phi = nullptr;
2017 const Type* this_type = this->bottom_type();
2018 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
2019 int this_index = C->get_alias_index(t_oop);
2020 int this_offset = t_oop->offset();
2021 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
2022 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
2023 } else if (ignore_missing_instance_id) {
2024 phi = new PhiNode(region, this_type, nullptr, mem->_idx);
2025 } else {
2026 return nullptr;
2027 }
2028
2029 for (uint i = 1; i < region->req(); i++) {
2030 Node* x;
2031 Node* the_clone = nullptr;
2032 Node* in = region->in(i);
2033 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
2034 in != nullptr && in->is_OuterStripMinedLoop()) {
2035 // No node should go in the outer strip mined loop
2036 in = in->in(LoopNode::EntryControl);
2037 }
2038 if (in == nullptr || in == C->top()) {
2039 x = C->top(); // Dead path? Use a dead data op
2040 } else {
2041 x = this->clone(); // Else clone up the data op
2042 the_clone = x; // Remember for possible deletion.
2043 // Alter data node to use pre-phi inputs
2044 if (this->in(0) == region) {
2045 x->set_req(0, in);
2046 } else {
2047 x->set_req(0, nullptr);
2048 }
2049 if (mem->is_Phi() && (mem->in(0) == region)) {
2050 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
2051 }
2052 if (address->is_Phi() && address->in(0) == region) {
2053 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
2054 }
2055 if (base_is_phi && (base->in(0) == region)) {
2056 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
2057 Node* adr_x = phase->transform(AddPNode::make_with_base(base_x, address->in(AddPNode::Offset)));
2058 x->set_req(Address, adr_x);
2059 }
2060 }
2061 // Check for a 'win' on some paths
2062 const Type *t = x->Value(igvn);
2063
2064 bool singleton = t->singleton();
2065
2066 // See comments in PhaseIdealLoop::split_thru_phi().
2067 if (singleton && t == Type::TOP) {
2068 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
2069 }
2070
2071 if (singleton) {
2072 x = igvn->makecon(t);
2073 } else {
2074 // We now call Identity to try to simplify the cloned node.
2075 // Note that some Identity methods call phase->type(this).
2076 // Make sure that the type array is big enough for
2077 // our new node, even though we may throw the node away.
2078 // (This tweaking with igvn only works because x is a new node.)
2079 igvn->set_type(x, t);
2080 // If x is a TypeNode, capture any more-precise type permanently into Node
2081 // otherwise it will be not updated during igvn->transform since
2082 // igvn->type(x) is set to x->Value() already.
2083 x->raise_bottom_type(t);
2084 Node* y = x->Identity(igvn);
2085 if (y != x) {
2086 x = y;
2087 } else {
2088 y = igvn->hash_find_insert(x);
2089 if (y) {
2090 x = y;
2091 } else {
2092 // Else x is a new node we are keeping
2093 // We do not need register_new_node_with_optimizer
2094 // because set_type has already been called.
2095 igvn->_worklist.push(x);
2096 }
2097 }
2098 }
2099 if (x != the_clone && the_clone != nullptr) {
2100 igvn->remove_dead_node(the_clone, PhaseIterGVN::NodeOrigin::Speculative);
2101 }
2102 phi->set_req(i, x);
2103 }
2104 // Record Phi
2105 igvn->register_new_node_with_optimizer(phi);
2106 return phi;
2107 }
2108
2109 AllocateNode* LoadNode::is_new_object_mark_load() const {
2110 if (Opcode() == Op_LoadX) {
2111 Node* address = in(MemNode::Address);
2112 AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
2113 Node* mem = in(MemNode::Memory);
2114 if (alloc != nullptr && mem->is_Proj() &&
2115 mem->in(0) != nullptr &&
2116 mem->in(0) == alloc->initialization() &&
2117 alloc->initialization()->proj_out_or_null(0) != nullptr) {
2118 return alloc;
2119 }
2120 }
2121 return nullptr;
2122 }
2123
2124
2125 //------------------------------Ideal------------------------------------------
2126 // If the load is from Field memory and the pointer is non-null, it might be possible to
2127 // zero out the control input.
2128 // If the offset is constant and the base is an object allocation,
2129 // try to hook me up to the exact initializing store.
2130 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2131 if (has_pinned_control_dependency()) {
2132 return nullptr;
2133 }
2134 Node* p = MemNode::Ideal_common(phase, can_reshape);
2135 if (p) return (p == NodeSentinel) ? nullptr : p;
2136
2137 Node* ctrl = in(MemNode::Control);
2138 Node* address = in(MemNode::Address);
2139
2140 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
2141 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
2142
2143 // Skip up past a SafePoint control. Cannot do this for Stores because
2144 // pointer stores & cardmarks must stay on the same side of a SafePoint.
2145 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
2146 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
2147 !addr_mark &&
2148 (depends_only_on_test() || has_unknown_control_dependency())) {
2149 ctrl = ctrl->in(0);
2150 set_req(MemNode::Control,ctrl);
2151 return this;
2152 }
2153
2154 intptr_t ignore = 0;
2155 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
2156 if (base != nullptr
2157 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
2158 // Check for useless control edge in some common special cases
2159 if (in(MemNode::Control) != nullptr
2160 // TODO 8350865 Can we re-enable this?
2161 && !(phase->type(address)->is_inlinetypeptr() && is_mismatched_access())
2162 && can_remove_control()
2163 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
2164 && all_controls_dominate(base, phase->C->start(), phase)) {
2165 // A method-invariant, non-null address (constant or 'this' argument).
2166 set_req(MemNode::Control, nullptr);
2167 return this;
2168 }
2169 }
2170
2171 Node* mem = in(MemNode::Memory);
2172 const TypePtr *addr_t = phase->type(address)->isa_ptr();
2173
2174 if (can_reshape && (addr_t != nullptr)) {
2175 // try to optimize our memory input
2176 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
2177 if (opt_mem != mem) {
2178 set_req_X(MemNode::Memory, opt_mem, phase);
2179 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
2180 return this;
2181 }
2182 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
2183 if ((t_oop != nullptr) &&
2184 (t_oop->is_known_instance_field() ||
2185 t_oop->is_ptr_to_boxed_value())) {
2186 PhaseIterGVN *igvn = phase->is_IterGVN();
2187 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
2188 if (igvn->_worklist.member(opt_mem)) {
2189 // Delay this transformation until memory Phi is processed.
2190 igvn->_worklist.push(this);
2191 return nullptr;
2192 }
2193 // Split instance field load through Phi.
2194 Node* result = split_through_phi(phase);
2195 if (result != nullptr) return result;
2196
2197 if (t_oop->is_ptr_to_boxed_value()) {
2198 Node* result = eliminate_autobox(igvn);
2199 if (result != nullptr) return result;
2200 }
2201 }
2202 }
2203
2204 // Is there a dominating load that loads the same value? Leave
2205 // anything that is not a load of a field/array element (like
2206 // barriers etc.) alone
2207 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
2208 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
2209 Node *use = mem->fast_out(i);
2210 if (use != this &&
2211 use->Opcode() == Opcode() &&
2212 use->in(0) != nullptr &&
2213 use->in(0) != in(0) &&
2214 use->in(Address) == in(Address)) {
2215 Node* ctl = in(0);
2216 for (int i = 0; i < 10 && ctl != nullptr; i++) {
2217 ctl = IfNode::up_one_dom(ctl);
2218 if (ctl == use->in(0)) {
2219 set_req(0, use->in(0));
2220 return this;
2221 }
2222 }
2223 }
2224 }
2225 }
2226
2227 // Check for prior store with a different base or offset; make Load
2228 // independent. Skip through any number of them. Bail out if the stores
2229 // are in an endless dead cycle and report no progress. This is a key
2230 // transform for Reflection. However, if after skipping through the Stores
2231 // we can't then fold up against a prior store do NOT do the transform as
2232 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
2233 // array memory alive twice: once for the hoisted Load and again after the
2234 // bypassed Store. This situation only works if EVERYBODY who does
2235 // anti-dependence work knows how to bypass. I.e. we need all
2236 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
2237 // the alias index stuff. So instead, peek through Stores and IFF we can
2238 // fold up, do so.
2239 Node* prev_mem = find_previous_store(phase);
2240 if (prev_mem != nullptr && prev_mem->is_top()) {
2241 // find_previous_store returns top when the access is dead
2242 return prev_mem;
2243 }
2244 if (prev_mem != nullptr) {
2245 Node* value = can_see_arraycopy_value(prev_mem, phase);
2246 if (value != nullptr) {
2247 return value;
2248 }
2249 }
2250 // Steps (a), (b): Walk past independent stores to find an exact match.
2251 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
2252 // (c) See if we can fold up on the spot, but don't fold up here.
2253 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
2254 // just return a prior value, which is done by Identity calls.
2255 if (can_see_stored_value_through_membars(prev_mem, phase)) {
2256 // Make ready for step (d):
2257 set_req_X(MemNode::Memory, prev_mem, phase);
2258 return this;
2259 }
2260 }
2261
2262 if (!can_reshape) {
2263 phase->record_for_igvn(this);
2264 }
2265
2266 return nullptr;
2267 }
2268
2269 // Helper to recognize certain Klass fields which are invariant across
2270 // some group of array types (e.g., int[] or all T[] where T < Object).
2271 const Type*
2272 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
2273 ciKlass* klass) const {
2274 assert(!UseCompactObjectHeaders || tkls->offset() != in_bytes(Klass::prototype_header_offset()),
2275 "must not happen");
2276
2277 if (tkls->isa_instklassptr() && tkls->offset() == in_bytes(InstanceKlass::access_flags_offset())) {
2278 // The field is InstanceKlass::_access_flags. Return its (constant) value.
2279 assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags");
2280 ciInstanceKlass* iklass = tkls->is_instklassptr()->instance_klass();
2281 return TypeInt::make(iklass->access_flags());
2282 }
2283 if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) {
2284 // The field is Klass::_misc_flags. Return its (constant) value.
2285 assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags");
2286 return TypeInt::make(klass->misc_flags());
2287 }
2288 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
2289 // The field is Klass::_layout_helper. Return its constant value if known.
2290 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2291 return TypeInt::make(klass->layout_helper());
2292 }
2293
2294 // No match.
2295 return nullptr;
2296 }
2297
2298 //------------------------------Value-----------------------------------------
2299 const Type* LoadNode::Value(PhaseGVN* phase) const {
2300 // Either input is TOP ==> the result is TOP
2301 Node* mem = in(MemNode::Memory);
2302 const Type *t1 = phase->type(mem);
2303 if (t1 == Type::TOP) return Type::TOP;
2304 Node* adr = in(MemNode::Address);
2305 const TypePtr* tp = phase->type(adr)->isa_ptr();
2306 if (tp == nullptr || tp->empty()) return Type::TOP;
2307 int off = tp->offset();
2308 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
2309 Compile* C = phase->C;
2310
2311 // If load can see a previous constant store, use that.
2312 Node* value = can_see_stored_value_through_membars(mem, phase);
2313 if (value != nullptr && value->is_Con()) {
2314 if (phase->type(value)->isa_ptr() && _type->isa_narrowoop()) {
2315 return phase->type(value)->make_narrowoop();
2316 } else {
2317 assert(value->bottom_type()->higher_equal(_type), "sanity");
2318 return phase->type(value);
2319 }
2320 }
2321 // Try to guess loaded type from pointer type
2322 if (tp->isa_aryptr()) {
2323 const TypeAryPtr* ary = tp->is_aryptr();
2324 const Type* t = ary->elem();
2325
2326 // Determine whether the reference is beyond the header or not, by comparing
2327 // the offset against the offset of the start of the array's data.
2328 // Different array types begin at slightly different offsets (12 vs. 16).
2329 // We choose T_BYTE as an example base type that is least restrictive
2330 // as to alignment, which will therefore produce the smallest
2331 // possible base offset.
2332 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2333 const bool off_beyond_header = (off >= min_base_off);
2334
2335 // Try to constant-fold a stable array element.
2336 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2337 // Make sure the reference is not into the header and the offset is constant
2338 ciObject* aobj = ary->const_oop();
2339 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2340 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2341 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off, ary->field_offset().get(),
2342 stable_dimension,
2343 value_basic_type(), is_unsigned());
2344 if (con_type != nullptr) {
2345 return con_type;
2346 }
2347 }
2348 }
2349
2350 // Don't do this for integer types. There is only potential profit if
2351 // the element type t is lower than _type; that is, for int types, if _type is
2352 // more restrictive than t. This only happens here if one is short and the other
2353 // char (both 16 bits), and in those cases we've made an intentional decision
2354 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2355 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2356 //
2357 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2358 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
2359 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2360 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
2361 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2362 // In fact, that could have been the original type of p1, and p1 could have
2363 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2364 // expression (LShiftL quux 3) independently optimized to the constant 8.
2365 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2366 && (_type->isa_vect() == nullptr)
2367 && !ary->is_flat()
2368 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2369 // t might actually be lower than _type, if _type is a unique
2370 // concrete subclass of abstract class t.
2371 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
2372 const Type* jt = t->join_speculative(_type);
2373 // In any case, do not allow the join, per se, to empty out the type.
2374 if (jt->empty() && !t->empty()) {
2375 // This can happen if a interface-typed array narrows to a class type.
2376 jt = _type;
2377 }
2378 #ifdef ASSERT
2379 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2380 // The pointers in the autobox arrays are always non-null
2381 Node* base = adr->in(AddPNode::Base);
2382 if ((base != nullptr) && base->is_DecodeN()) {
2383 // Get LoadN node which loads IntegerCache.cache field
2384 base = base->in(1);
2385 }
2386 if ((base != nullptr) && base->is_Con()) {
2387 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2388 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2389 // It could be narrow oop
2390 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2391 }
2392 }
2393 }
2394 #endif
2395 return jt;
2396 }
2397 }
2398 } else if (tp->base() == Type::InstPtr) {
2399 assert( off != Type::OffsetBot ||
2400 // arrays can be cast to Objects
2401 !tp->isa_instptr() ||
2402 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2403 // Default value load
2404 tp->is_instptr()->instance_klass() == ciEnv::current()->Class_klass() ||
2405 // unsafe field access may not have a constant offset
2406 C->has_unsafe_access(),
2407 "Field accesses must be precise" );
2408 // For oop loads, we expect the _type to be precise.
2409
2410 const TypeInstPtr* tinst = tp->is_instptr();
2411 BasicType bt = value_basic_type();
2412
2413 // Fold loads of the field map
2414 if (tinst != nullptr) {
2415 ciInstanceKlass* ik = tinst->instance_klass();
2416 int offset = tinst->offset();
2417 if (ik == phase->C->env()->Class_klass()) {
2418 ciType* t = tinst->java_mirror_type();
2419 if (t != nullptr && t->is_inlinetype() && offset == t->as_inline_klass()->field_map_offset()) {
2420 ciConstant map = t->as_inline_klass()->get_field_map();
2421 bool is_narrow_oop = (bt == T_NARROWOOP);
2422 return Type::make_from_constant(map, true, 1, is_narrow_oop);
2423 }
2424 }
2425 }
2426
2427 // Optimize loads from constant fields.
2428 ciObject* const_oop = tinst->const_oop();
2429 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2430 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
2431 if (con_type != nullptr) {
2432 return con_type;
2433 }
2434 }
2435 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2436 assert(off != Type::OffsetBot ||
2437 !tp->isa_instklassptr() ||
2438 // arrays can be cast to Objects
2439 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2440 // also allow array-loading from the primary supertype
2441 // array during subtype checks
2442 Opcode() == Op_LoadKlass,
2443 "Field accesses must be precise");
2444 // For klass/static loads, we expect the _type to be precise
2445 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2446 /* With mirrors being an indirect in the Klass*
2447 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2448 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2449 *
2450 * So check the type and klass of the node before the LoadP.
2451 */
2452 Node* adr2 = adr->in(MemNode::Address);
2453 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2454 if (tkls != nullptr && !StressReflectiveCode) {
2455 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2456 ciKlass* klass = tkls->exact_klass();
2457 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2458 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2459 return TypeInstPtr::make(klass->java_mirror());
2460 }
2461 }
2462 }
2463
2464 const TypeKlassPtr *tkls = tp->isa_klassptr();
2465 if (tkls != nullptr) {
2466 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2467 ciKlass* klass = tkls->exact_klass();
2468 // We are loading a field from a Klass metaobject whose identity
2469 // is known at compile time (the type is "exact" or "precise").
2470 // Check for fields we know are maintained as constants by the VM.
2471 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2472 // The field is Klass::_super_check_offset. Return its (constant) value.
2473 // (Folds up type checking code.)
2474 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2475 return TypeInt::make(klass->super_check_offset());
2476 }
2477 if (klass->is_inlinetype() && tkls->offset() == in_bytes(InstanceKlass::acmp_maps_offset_offset())) {
2478 return TypeInt::make(klass->as_inline_klass()->field_map_offset());
2479 }
2480 if (klass->is_obj_array_klass() && tkls->offset() == in_bytes(ObjArrayKlass::next_refined_array_klass_offset())) {
2481 // Fold loads from LibraryCallKit::load_default_refined_array_klass
2482 return tkls->is_aryklassptr()->cast_to_refined_array_klass_ptr();
2483 }
2484 if (klass->is_array_klass() && tkls->offset() == in_bytes(ObjArrayKlass::properties_offset())) {
2485 assert(klass->is_type_array_klass() || tkls->is_aryklassptr()->is_refined_type(), "Must be a refined array klass pointer");
2486 return TypeInt::make((jint)klass->as_array_klass()->properties().value());
2487 }
2488 if (klass->is_flat_array_klass() && tkls->offset() == in_bytes(FlatArrayKlass::layout_kind_offset())) {
2489 assert(Opcode() == Op_LoadI, "must load an int from _layout_kind");
2490 return TypeInt::make(static_cast<jint>(klass->as_flat_array_klass()->layout_kind()));
2491 }
2492 if (UseCompactObjectHeaders && tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2493 // The field is Klass::_prototype_header. Return its (constant) value.
2494 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2495 return TypeX::make(klass->prototype_header());
2496 }
2497 // Compute index into primary_supers array
2498 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2499 // Check for overflowing; use unsigned compare to handle the negative case.
2500 if( depth < ciKlass::primary_super_limit() ) {
2501 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2502 // (Folds up type checking code.)
2503 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2504 ciKlass *ss = klass->super_of_depth(depth);
2505 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2506 }
2507 const Type* aift = load_array_final_field(tkls, klass);
2508 if (aift != nullptr) return aift;
2509 }
2510
2511 // We can still check if we are loading from the primary_supers array at a
2512 // shallow enough depth. Even though the klass is not exact, entries less
2513 // than or equal to its super depth are correct.
2514 if (tkls->is_loaded()) {
2515 ciKlass* klass = nullptr;
2516 if (tkls->isa_instklassptr()) {
2517 klass = tkls->is_instklassptr()->instance_klass();
2518 } else {
2519 int dims;
2520 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2521 if (inner->isa_instklassptr()) {
2522 klass = inner->is_instklassptr()->instance_klass();
2523 klass = ciObjArrayKlass::make(klass, dims);
2524 }
2525 }
2526 if (klass != nullptr) {
2527 // Compute index into primary_supers array
2528 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2529 // Check for overflowing; use unsigned compare to handle the negative case.
2530 if (depth < ciKlass::primary_super_limit() &&
2531 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2532 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2533 // (Folds up type checking code.)
2534 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2535 ciKlass *ss = klass->super_of_depth(depth);
2536 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2537 }
2538 }
2539 }
2540
2541 // If the type is enough to determine that the thing is not an array,
2542 // we can give the layout_helper a positive interval type.
2543 // This will help short-circuit some reflective code.
2544 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2545 tkls->isa_instklassptr() && // not directly typed as an array
2546 !tkls->is_instklassptr()->might_be_an_array() // not the supertype of all T[] (java.lang.Object) or has an interface that is not Serializable or Cloneable
2547 ) {
2548 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2549 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2550 // The key property of this type is that it folds up tests
2551 // for array-ness, since it proves that the layout_helper is positive.
2552 // Thus, a generic value like the basic object layout helper works fine.
2553 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2554 }
2555 }
2556
2557 // If we are loading from a freshly-allocated object/array, produce a zero.
2558 // Things to check:
2559 // 1. Load is beyond the header: headers are not guaranteed to be zero
2560 // 2. Load is not vectorized: vectors have no zero constant
2561 // 3. Load has no matching store, i.e. the input is the initial memory state
2562 const TypeOopPtr* tinst = tp->isa_oopptr();
2563 bool is_not_header = (tinst != nullptr) && tinst->is_known_instance_field();
2564 bool is_not_vect = (_type->isa_vect() == nullptr);
2565 if (is_not_header && is_not_vect) {
2566 Node* mem = in(MemNode::Memory);
2567 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2568 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2569 // TODO 8350865 Scalar replacement does not work well for flat arrays.
2570 // Escape Analysis assumes that arrays are always zeroed during allocation which is not true for null-free arrays
2571 // ConnectionGraph::split_unique_types will re-wire the memory of loads from such arrays around the allocation
2572 // TestArrays::test6 and test152 and TestBasicFunctionality::test20 are affected by this.
2573 if (tp->isa_aryptr() && tp->is_aryptr()->is_flat() && tp->is_aryptr()->is_null_free()) {
2574 intptr_t offset = 0;
2575 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2576 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
2577 if (alloc != nullptr && alloc->is_AllocateArray() && alloc->in(AllocateNode::InitValue) != nullptr) {
2578 return _type;
2579 }
2580 }
2581 return Type::get_zero_type(_type->basic_type());
2582 }
2583 }
2584 if (!UseCompactObjectHeaders) {
2585 Node* alloc = is_new_object_mark_load();
2586 if (alloc != nullptr) {
2587 if (Arguments::is_valhalla_enabled()) {
2588 // The mark word may contain property bits (inline, flat, null-free)
2589 Node* klass_node = alloc->in(AllocateNode::KlassNode);
2590 const TypeKlassPtr* tkls = phase->type(klass_node)->isa_klassptr();
2591 if (tkls != nullptr && tkls->is_loaded() && tkls->klass_is_exact()) {
2592 return TypeX::make(tkls->exact_klass()->prototype_header());
2593 }
2594 } else {
2595 return TypeX::make(markWord::prototype().value());
2596 }
2597 }
2598 }
2599
2600 return _type;
2601 }
2602
2603 //------------------------------match_edge-------------------------------------
2604 // Do we Match on this edge index or not? Match only the address.
2605 uint LoadNode::match_edge(uint idx) const {
2606 return idx == MemNode::Address;
2607 }
2608
2609 //--------------------------LoadBNode::Ideal--------------------------------------
2610 //
2611 // If the previous store is to the same address as this load,
2612 // and the value stored was larger than a byte, replace this load
2613 // with the value stored truncated to a byte. If no truncation is
2614 // needed, the replacement is done in LoadNode::Identity().
2615 //
2616 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2617 Node* mem = in(MemNode::Memory);
2618 Node* value = can_see_stored_value_through_membars(mem, phase);
2619 if (value != nullptr) {
2620 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2621 if (narrow != value) {
2622 return narrow;
2623 }
2624 }
2625 // Identity call will handle the case where truncation is not needed.
2626 return LoadNode::Ideal(phase, can_reshape);
2627 }
2628
2629 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2630 Node* mem = in(MemNode::Memory);
2631 Node* value = can_see_stored_value_through_membars(mem, phase);
2632 if (value != nullptr && value->is_Con() &&
2633 !value->bottom_type()->higher_equal(_type)) {
2634 // If the input to the store does not fit with the load's result type,
2635 // it must be truncated. We can't delay until Ideal call since
2636 // a singleton Value is needed for split_thru_phi optimization.
2637 int con = value->get_int();
2638 return TypeInt::make((con << 24) >> 24);
2639 }
2640 return LoadNode::Value(phase);
2641 }
2642
2643 //--------------------------LoadUBNode::Ideal-------------------------------------
2644 //
2645 // If the previous store is to the same address as this load,
2646 // and the value stored was larger than a byte, replace this load
2647 // with the value stored truncated to a byte. If no truncation is
2648 // needed, the replacement is done in LoadNode::Identity().
2649 //
2650 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2651 Node* mem = in(MemNode::Memory);
2652 Node* value = can_see_stored_value_through_membars(mem, phase);
2653 if (value != nullptr) {
2654 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2655 if (narrow != value) {
2656 return narrow;
2657 }
2658 }
2659 // Identity call will handle the case where truncation is not needed.
2660 return LoadNode::Ideal(phase, can_reshape);
2661 }
2662
2663 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2664 Node* mem = in(MemNode::Memory);
2665 Node* value = can_see_stored_value_through_membars(mem, phase);
2666 if (value != nullptr && value->is_Con() &&
2667 !value->bottom_type()->higher_equal(_type)) {
2668 // If the input to the store does not fit with the load's result type,
2669 // it must be truncated. We can't delay until Ideal call since
2670 // a singleton Value is needed for split_thru_phi optimization.
2671 int con = value->get_int();
2672 return TypeInt::make(con & 0xFF);
2673 }
2674 return LoadNode::Value(phase);
2675 }
2676
2677 //--------------------------LoadUSNode::Ideal-------------------------------------
2678 //
2679 // If the previous store is to the same address as this load,
2680 // and the value stored was larger than a char, replace this load
2681 // with the value stored truncated to a char. If no truncation is
2682 // needed, the replacement is done in LoadNode::Identity().
2683 //
2684 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2685 Node* mem = in(MemNode::Memory);
2686 Node* value = can_see_stored_value_through_membars(mem, phase);
2687 if (value != nullptr) {
2688 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2689 if (narrow != value) {
2690 return narrow;
2691 }
2692 }
2693 // Identity call will handle the case where truncation is not needed.
2694 return LoadNode::Ideal(phase, can_reshape);
2695 }
2696
2697 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2698 Node* mem = in(MemNode::Memory);
2699 Node* value = can_see_stored_value_through_membars(mem, phase);
2700 if (value != nullptr && value->is_Con() &&
2701 !value->bottom_type()->higher_equal(_type)) {
2702 // If the input to the store does not fit with the load's result type,
2703 // it must be truncated. We can't delay until Ideal call since
2704 // a singleton Value is needed for split_thru_phi optimization.
2705 int con = value->get_int();
2706 return TypeInt::make(con & 0xFFFF);
2707 }
2708 return LoadNode::Value(phase);
2709 }
2710
2711 //--------------------------LoadSNode::Ideal--------------------------------------
2712 //
2713 // If the previous store is to the same address as this load,
2714 // and the value stored was larger than a short, replace this load
2715 // with the value stored truncated to a short. If no truncation is
2716 // needed, the replacement is done in LoadNode::Identity().
2717 //
2718 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2719 Node* mem = in(MemNode::Memory);
2720 Node* value = can_see_stored_value_through_membars(mem, phase);
2721 if (value != nullptr) {
2722 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2723 if (narrow != value) {
2724 return narrow;
2725 }
2726 }
2727 // Identity call will handle the case where truncation is not needed.
2728 return LoadNode::Ideal(phase, can_reshape);
2729 }
2730
2731 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2732 Node* mem = in(MemNode::Memory);
2733 Node* value = can_see_stored_value_through_membars(mem, phase);
2734 if (value != nullptr && value->is_Con() &&
2735 !value->bottom_type()->higher_equal(_type)) {
2736 // If the input to the store does not fit with the load's result type,
2737 // it must be truncated. We can't delay until Ideal call since
2738 // a singleton Value is needed for split_thru_phi optimization.
2739 int con = value->get_int();
2740 return TypeInt::make((con << 16) >> 16);
2741 }
2742 return LoadNode::Value(phase);
2743 }
2744
2745 Node* LoadNNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2746 // Loading from an InlineType, find the input and make an EncodeP
2747 Node* addr = in(Address);
2748 intptr_t offset;
2749 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
2750 Node* value = see_through_inline_type(phase, this, base, offset);
2751 if (value != nullptr) {
2752 return new EncodePNode(value, type());
2753 }
2754
2755 // Can see the corresponding value, may need to add an EncodeP
2756 value = can_see_stored_value(in(Memory), phase);
2757 if (value != nullptr && phase->type(value)->isa_ptr() && type()->isa_narrowoop()) {
2758 return new EncodePNode(value, type());
2759 }
2760
2761 // Identity call will handle the case where EncodeP is unnecessary
2762 return LoadNode::Ideal(phase, can_reshape);
2763 }
2764
2765 //=============================================================================
2766 //----------------------------LoadKlassNode::make------------------------------
2767 // Polymorphic factory method:
2768 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk) {
2769 // sanity check the alias category against the created node type
2770 const TypePtr* adr_type = adr->bottom_type()->isa_ptr();
2771 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2772 #ifdef _LP64
2773 if (adr_type->is_ptr_to_narrowklass()) {
2774 Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered));
2775 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2776 }
2777 #endif
2778 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2779 return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered);
2780 }
2781
2782 //------------------------------Value------------------------------------------
2783 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2784 return klass_value_common(phase);
2785 }
2786
2787 const Type* LoadNode::klass_value_common(PhaseGVN* phase) const {
2788 // Either input is TOP ==> the result is TOP
2789 const Type *t1 = phase->type( in(MemNode::Memory) );
2790 if (t1 == Type::TOP) return Type::TOP;
2791 Node *adr = in(MemNode::Address);
2792 const Type *t2 = phase->type( adr );
2793 if (t2 == Type::TOP) return Type::TOP;
2794 const TypePtr *tp = t2->is_ptr();
2795 if (TypePtr::above_centerline(tp->ptr()) ||
2796 tp->ptr() == TypePtr::Null) return Type::TOP;
2797
2798 // Return a more precise klass, if possible
2799 const TypeInstPtr *tinst = tp->isa_instptr();
2800 if (tinst != nullptr) {
2801 ciInstanceKlass* ik = tinst->instance_klass();
2802 int offset = tinst->offset();
2803 if (ik == phase->C->env()->Class_klass()
2804 && (offset == java_lang_Class::klass_offset() ||
2805 offset == java_lang_Class::array_klass_offset())) {
2806 // We are loading a special hidden field from a Class mirror object,
2807 // the field which points to the VM's Klass metaobject.
2808 ciType* t = tinst->java_mirror_type();
2809 // java_mirror_type returns non-null for compile-time Class constants.
2810 if (t != nullptr) {
2811 // constant oop => constant klass
2812 if (offset == java_lang_Class::array_klass_offset()) {
2813 if (t->is_void()) {
2814 // We cannot create a void array. Since void is a primitive type return null
2815 // klass. Users of this result need to do a null check on the returned klass.
2816 return TypePtr::NULL_PTR;
2817 }
2818 return TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2819 }
2820 if (!t->is_klass()) {
2821 // a primitive Class (e.g., int.class) has null for a klass field
2822 return TypePtr::NULL_PTR;
2823 }
2824 // Fold up the load of the hidden field
2825 return TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2826 }
2827 // non-constant mirror, so we can't tell what's going on
2828 }
2829 if (!tinst->is_loaded())
2830 return _type; // Bail out if not loaded
2831 if (offset == oopDesc::klass_offset_in_bytes()) {
2832 return tinst->as_klass_type(true);
2833 }
2834 }
2835
2836 // Check for loading klass from an array
2837 const TypeAryPtr* tary = tp->isa_aryptr();
2838 if (tary != nullptr &&
2839 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2840 return tary->as_klass_type(true)->is_aryklassptr();
2841 }
2842
2843 // Check for loading klass from an array klass
2844 const TypeKlassPtr *tkls = tp->isa_klassptr();
2845 if (tkls != nullptr && !StressReflectiveCode) {
2846 if (!tkls->is_loaded())
2847 return _type; // Bail out if not loaded
2848 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2849 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2850 // // Always returning precise element type is incorrect,
2851 // // e.g., element type could be object and array may contain strings
2852 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2853
2854 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2855 // according to the element type's subclassing.
2856 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2857 }
2858 if (tkls->isa_aryklassptr() != nullptr && tkls->klass_is_exact() &&
2859 !tkls->exact_klass()->is_type_array_klass() &&
2860 tkls->offset() == in_bytes(Klass::super_offset())) {
2861 // We are loading the super klass of a refined array klass, return the non-refined klass pointer
2862 assert(tkls->is_aryklassptr()->is_refined_type(), "Must be a refined array klass pointer");
2863 return tkls->is_aryklassptr()->with_offset(0)->cast_to_non_refined();
2864 }
2865 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2866 tkls->offset() == in_bytes(Klass::super_offset())) {
2867 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2868 // The field is Klass::_super. Return its (constant) value.
2869 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2870 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2871 }
2872 }
2873
2874 if (tkls != nullptr && !UseSecondarySupersCache
2875 && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset())) {
2876 // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2877 return TypePtr::NULL_PTR;
2878 }
2879
2880 // Bailout case
2881 return LoadNode::Value(phase);
2882 }
2883
2884 //------------------------------Identity---------------------------------------
2885 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2886 // Also feed through the klass in Allocate(...klass...)._klass.
2887 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2888 return klass_identity_common(phase);
2889 }
2890
2891 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2892 Node* x = LoadNode::Identity(phase);
2893 if (x != this) return x;
2894
2895 // Take apart the address into an oop and offset.
2896 // Return 'this' if we cannot.
2897 Node* adr = in(MemNode::Address);
2898 intptr_t offset = 0;
2899 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2900 if (base == nullptr) return this;
2901 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2902 if (toop == nullptr) return this;
2903
2904 // Step over potential GC barrier for OopHandle resolve
2905 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2906 if (bs->is_gc_barrier_node(base)) {
2907 base = bs->step_over_gc_barrier(base);
2908 }
2909
2910 // We can fetch the klass directly through an AllocateNode.
2911 // This works even if the klass is not constant (clone or newArray).
2912 if (offset == oopDesc::klass_offset_in_bytes()) {
2913 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2914 if (allocated_klass != nullptr) {
2915 return allocated_klass;
2916 }
2917 }
2918
2919 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2920 // See inline_native_Class_query for occurrences of these patterns.
2921 // Java Example: x.getClass().isAssignableFrom(y)
2922 //
2923 // This improves reflective code, often making the Class
2924 // mirror go completely dead. (Current exception: Class
2925 // mirrors may appear in debug info, but we could clean them out by
2926 // introducing a new debug info operator for Klass.java_mirror).
2927 //
2928 // This optimization does not apply to arrays because if k is not a
2929 // constant, it was obtained via load_klass which returns the VM type
2930 // and '.java_mirror.as_klass' should return the Java type instead.
2931
2932 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2933 && offset == java_lang_Class::klass_offset()) {
2934 if (base->is_Load()) {
2935 Node* base2 = base->in(MemNode::Address);
2936 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2937 Node* adr2 = base2->in(MemNode::Address);
2938 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2939 if (tkls != nullptr && !tkls->empty()
2940 && ((tkls->isa_instklassptr() && !tkls->is_instklassptr()->might_be_an_array()))
2941 && adr2->is_AddP()) {
2942 int mirror_field = in_bytes(Klass::java_mirror_offset());
2943 if (tkls->offset() == mirror_field) {
2944 #ifdef ASSERT
2945 const TypeKlassPtr* tkls2 = phase->type(adr2->in(AddPNode::Address))->is_klassptr();
2946 assert(tkls2->offset() == 0, "not a load of java_mirror");
2947 #endif
2948 assert(adr2->in(AddPNode::Base)->is_top(), "not an off heap load");
2949 assert(adr2->in(AddPNode::Offset)->find_intptr_t_con(-1) == in_bytes(Klass::java_mirror_offset()), "incorrect offset");
2950 return adr2->in(AddPNode::Address);
2951 }
2952 }
2953 }
2954 }
2955 }
2956
2957 return this;
2958 }
2959
2960 LoadNode* LoadNode::clone_pinned() const {
2961 LoadNode* ld = clone()->as_Load();
2962 ld->_control_dependency = UnknownControl;
2963 return ld;
2964 }
2965
2966 // Pin a LoadNode if it carries a dependency on its control input. There are cases when the node
2967 // does not actually have any dependency on its control input. For example, if we have a LoadNode
2968 // being used only outside a loop but it must be scheduled inside the loop, we can clone the node
2969 // for each of its use so that all the clones can be scheduled outside the loop. Then, to prevent
2970 // the clones from being GVN-ed again, we add a control input for each of them at the loop exit. In
2971 // those case, since there is not a dependency between the node and its control input, we do not
2972 // need to pin it.
2973 LoadNode* LoadNode::pin_node_under_control_impl() const {
2974 const TypePtr* adr_type = this->adr_type();
2975 if (adr_type != nullptr && adr_type->isa_aryptr()) {
2976 // Only array accesses have dependencies on their control input
2977 return clone_pinned();
2978 }
2979 return nullptr;
2980 }
2981
2982 //------------------------------Value------------------------------------------
2983 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2984 const Type *t = klass_value_common(phase);
2985 if (t == Type::TOP)
2986 return t;
2987
2988 return t->make_narrowklass();
2989 }
2990
2991 //------------------------------Identity---------------------------------------
2992 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2993 // Also feed through the klass in Allocate(...klass...)._klass.
2994 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2995 Node *x = klass_identity_common(phase);
2996
2997 const Type *t = phase->type( x );
2998 if( t == Type::TOP ) return x;
2999 if( t->isa_narrowklass()) return x;
3000 assert (!t->isa_narrowoop(), "no narrow oop here");
3001
3002 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
3003 }
3004
3005 //------------------------------Value-----------------------------------------
3006 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
3007 // Either input is TOP ==> the result is TOP
3008 const Type *t1 = phase->type( in(MemNode::Memory) );
3009 if( t1 == Type::TOP ) return Type::TOP;
3010 Node *adr = in(MemNode::Address);
3011 const Type *t2 = phase->type( adr );
3012 if( t2 == Type::TOP ) return Type::TOP;
3013 const TypePtr *tp = t2->is_ptr();
3014 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
3015 const TypeAryPtr *tap = tp->isa_aryptr();
3016 if( !tap ) return _type;
3017 return tap->size();
3018 }
3019
3020 //-------------------------------Ideal---------------------------------------
3021 // Feed through the length in AllocateArray(...length...)._length.
3022 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3023 Node* p = MemNode::Ideal_common(phase, can_reshape);
3024 if (p) return (p == NodeSentinel) ? nullptr : p;
3025
3026 // Take apart the address into an oop and offset.
3027 // Return 'this' if we cannot.
3028 Node* adr = in(MemNode::Address);
3029 intptr_t offset = 0;
3030 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
3031 if (base == nullptr) return nullptr;
3032 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
3033 if (tary == nullptr) return nullptr;
3034
3035 // We can fetch the length directly through an AllocateArrayNode.
3036 // This works even if the length is not constant (clone or newArray).
3037 if (offset == arrayOopDesc::length_offset_in_bytes()) {
3038 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
3039 if (alloc != nullptr) {
3040 Node* allocated_length = alloc->Ideal_length();
3041 Node* len = alloc->make_ideal_length(tary, phase);
3042 if (allocated_length != len) {
3043 // New CastII improves on this.
3044 return len;
3045 }
3046 }
3047 }
3048
3049 return nullptr;
3050 }
3051
3052 //------------------------------Identity---------------------------------------
3053 // Feed through the length in AllocateArray(...length...)._length.
3054 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
3055 Node* x = LoadINode::Identity(phase);
3056 if (x != this) return x;
3057
3058 // Take apart the address into an oop and offset.
3059 // Return 'this' if we cannot.
3060 Node* adr = in(MemNode::Address);
3061 intptr_t offset = 0;
3062 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
3063 if (base == nullptr) return this;
3064 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
3065 if (tary == nullptr) return this;
3066
3067 // We can fetch the length directly through an AllocateArrayNode.
3068 // This works even if the length is not constant (clone or newArray).
3069 if (offset == arrayOopDesc::length_offset_in_bytes()) {
3070 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
3071 if (alloc != nullptr) {
3072 Node* allocated_length = alloc->Ideal_length();
3073 // Do not allow make_ideal_length to allocate a CastII node.
3074 Node* len = alloc->make_ideal_length(tary, phase, false);
3075 if (allocated_length == len) {
3076 // Return allocated_length only if it would not be improved by a CastII.
3077 return allocated_length;
3078 }
3079 }
3080 }
3081
3082 return this;
3083
3084 }
3085
3086 //=============================================================================
3087 //---------------------------StoreNode::make-----------------------------------
3088 // Polymorphic factory method:
3089 StoreNode* StoreNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, Node* val, BasicType bt, MemOrd mo, bool require_atomic_access) {
3090 assert((mo == unordered || mo == release), "unexpected");
3091 Compile* C = gvn.C;
3092 assert(adr_type == nullptr || adr->is_top() || C->get_alias_index(gvn.type(adr)->is_ptr()) == C->get_alias_index(adr_type), "adr and adr_type must agree");
3093 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
3094 ctl != nullptr, "raw memory operations should have control edge");
3095
3096 switch (bt) {
3097 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
3098 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
3099 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
3100 case T_CHAR:
3101 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
3102 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
3103 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
3104 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
3105 case T_METADATA:
3106 case T_ADDRESS:
3107 case T_OBJECT:
3108 case T_ARRAY:
3109 #ifdef _LP64
3110 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
3111 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
3112 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
3113 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
3114 (val->bottom_type()->isa_klassptr() && adr->bottom_type()->isa_rawptr())) {
3115 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
3116 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
3117 }
3118 #endif
3119 {
3120 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
3121 }
3122 default:
3123 guarantee(false, "unexpected basic type %s", type2name(bt));
3124 return (StoreNode*)nullptr;
3125 }
3126 }
3127
3128 //--------------------------bottom_type----------------------------------------
3129 const Type *StoreNode::bottom_type() const {
3130 return Type::MEMORY;
3131 }
3132
3133 //------------------------------hash-------------------------------------------
3134 uint StoreNode::hash() const {
3135 // unroll addition of interesting fields
3136 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
3137
3138 // Since they are not commoned, do not hash them:
3139 return NO_HASH;
3140 }
3141
3142 // Link together multiple stores (B/S/C/I) into a longer one.
3143 //
3144 // Example: _store = StoreB[i+3]
3145 //
3146 // RangeCheck[i+0] RangeCheck[i+0]
3147 // StoreB[i+0]
3148 // RangeCheck[i+3] RangeCheck[i+3]
3149 // StoreB[i+1] --> pass: fail:
3150 // StoreB[i+2] StoreI[i+0] StoreB[i+0]
3151 // StoreB[i+3]
3152 //
3153 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
3154 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
3155 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
3156 // failing path.
3157 //
3158 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
3159 // - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
3160 // and possibly no RangeChecks remain between the stores.
3161 // - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
3162 // and those later RangeChecks can be removed. Example:
3163 //
3164 // RangeCheck[i+0] RangeCheck[i+0] <- before first store
3165 // StoreB[i+0] StoreB[i+0] <- first store
3166 // RangeCheck[i+1] --> smeared --> RangeCheck[i+3] <- only RC between first and last store
3167 // StoreB[i+1] StoreB[i+1] <- second store
3168 // RangeCheck[i+2] --> removed
3169 // StoreB[i+2] StoreB[i+2]
3170 // RangeCheck[i+3] --> removed
3171 // StoreB[i+3] StoreB[i+3] <- last store
3172 //
3173 // Thus, it is a common pattern that between the first and last store in a chain
3174 // of adjacent stores there remains exactly one RangeCheck, located between the
3175 // first and the second store (e.g. RangeCheck[i+3]).
3176 //
3177 class MergePrimitiveStores : public StackObj {
3178 private:
3179 PhaseGVN* const _phase;
3180 StoreNode* const _store;
3181 // State machine with initial state Unknown
3182 // Allowed transitions:
3183 // Unknown -> Const
3184 // Unknown -> Platform
3185 // Unknown -> Reverse
3186 // Unknown -> NotAdjacent
3187 // Const -> Const
3188 // Const -> NotAdjacent
3189 // Platform -> Platform
3190 // Platform -> NotAdjacent
3191 // Reverse -> Reverse
3192 // Reverse -> NotAdjacent
3193 // NotAdjacent -> NotAdjacent
3194 enum ValueOrder : uint8_t {
3195 Unknown, // Initial state
3196 Const, // Input values are const
3197 Platform, // Platform order
3198 Reverse, // Reverse platform order
3199 NotAdjacent // Not adjacent
3200 };
3201 ValueOrder _value_order;
3202
3203 NOT_PRODUCT( const CHeapBitMap &_trace_tags; )
3204
3205 public:
3206 MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) :
3207 _phase(phase), _store(store), _value_order(ValueOrder::Unknown)
3208 NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) )
3209 {}
3210
3211 StoreNode* run();
3212
3213 private:
3214 bool is_compatible_store(const StoreNode* other_store) const;
3215 bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
3216 bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
3217 static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase);
3218 enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
3219 static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
3220
3221 class Status {
3222 private:
3223 StoreNode* _found_store;
3224 bool _found_range_check;
3225
3226 Status(StoreNode* found_store, bool found_range_check)
3227 : _found_store(found_store), _found_range_check(found_range_check) {}
3228
3229 public:
3230 StoreNode* found_store() const { return _found_store; }
3231 bool found_range_check() const { return _found_range_check; }
3232 static Status make_failure() { return Status(nullptr, false); }
3233
3234 static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
3235 if (cfg_status == CFGStatus::Failure) {
3236 return Status::make_failure();
3237 }
3238 return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
3239 }
3240
3241 #ifndef PRODUCT
3242 void print_on(outputStream* st) const {
3243 if (_found_store == nullptr) {
3244 st->print_cr("None");
3245 } else {
3246 st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(),
3247 _found_range_check ? "RC" : "no-RC");
3248 }
3249 }
3250 #endif
3251 };
3252
3253 enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const;
3254 Status find_adjacent_use_store(const StoreNode* def_store) const;
3255 Status find_adjacent_def_store(const StoreNode* use_store) const;
3256 Status find_use_store(const StoreNode* def_store) const;
3257 Status find_def_store(const StoreNode* use_store) const;
3258 Status find_use_store_unidirectional(const StoreNode* def_store) const;
3259 Status find_def_store_unidirectional(const StoreNode* use_store) const;
3260
3261 void collect_merge_list(Node_List& merge_list) const;
3262 Node* make_merged_input_value(const Node_List& merge_list);
3263 StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
3264
3265 #ifndef PRODUCT
3266 // Access to TraceMergeStores tags
3267 bool is_trace(TraceMergeStores::Tag tag) const {
3268 return _trace_tags.at(tag);
3269 }
3270
3271 bool is_trace_basic() const {
3272 return is_trace(TraceMergeStores::Tag::BASIC);
3273 }
3274
3275 bool is_trace_pointer_parsing() const {
3276 return is_trace(TraceMergeStores::Tag::POINTER_PARSING);
3277 }
3278
3279 bool is_trace_pointer_aliasing() const {
3280 return is_trace(TraceMergeStores::Tag::POINTER_ALIASING);
3281 }
3282
3283 bool is_trace_pointer_adjacency() const {
3284 return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY);
3285 }
3286
3287 bool is_trace_success() const {
3288 return is_trace(TraceMergeStores::Tag::SUCCESS);
3289 }
3290 #endif
3291
3292 NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
3293 };
3294
3295 StoreNode* MergePrimitiveStores::run() {
3296 // Check for B/S/C/I
3297 int opc = _store->Opcode();
3298 if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
3299 return nullptr;
3300 }
3301
3302 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); })
3303
3304 // The _store must be the "last" store in a chain. If we find a use we could merge with
3305 // then that use or a store further down is the "last" store.
3306 Status status_use = find_adjacent_use_store(_store);
3307 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); })
3308 if (status_use.found_store() != nullptr) {
3309 return nullptr;
3310 }
3311
3312 // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
3313 Status status_def = find_adjacent_def_store(_store);
3314 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); })
3315 Node* def_store = status_def.found_store();
3316 if (def_store == nullptr) {
3317 return nullptr;
3318 }
3319
3320 // Initialize value order
3321 _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn),
3322 _store->in(MemNode::ValueIn),
3323 _store->memory_size());
3324 assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked");
3325
3326 ResourceMark rm;
3327 Node_List merge_list;
3328 collect_merge_list(merge_list);
3329
3330 Node* merged_input_value = make_merged_input_value(merge_list);
3331 if (merged_input_value == nullptr) { return nullptr; }
3332
3333 StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
3334
3335 NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } )
3336
3337 return merged_store;
3338 }
3339
3340 // Check compatibility between _store and other_store.
3341 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const {
3342 int opc = _store->Opcode();
3343 assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
3344
3345 if (other_store == nullptr ||
3346 _store->Opcode() != other_store->Opcode()) {
3347 return false;
3348 }
3349
3350 return true;
3351 }
3352
3353 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
3354 if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
3355 use_store->in(MemNode::ValueIn),
3356 def_store->memory_size())) {
3357 return false;
3358 }
3359
3360 ResourceMark rm;
3361 #ifndef PRODUCT
3362 const TraceMemPointer trace(is_trace_pointer_parsing(),
3363 is_trace_pointer_aliasing(),
3364 is_trace_pointer_adjacency(),
3365 true);
3366 #endif
3367 const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace));
3368 const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace));
3369 return pointer_def.is_adjacent_to_and_before(pointer_use);
3370 }
3371
3372 // Check input values n1 and n2 can be merged and return the value order
3373 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2,
3374 const int memory_size) const {
3375 // Pattern: [n1 = ConI, n2 = ConI]
3376 if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) {
3377 return ValueOrder::Const;
3378 }
3379
3380 Node const *base_n2;
3381 jint shift_n2;
3382 if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) {
3383 return ValueOrder::NotAdjacent;
3384 }
3385 Node const *base_n1;
3386 jint shift_n1;
3387 if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) {
3388 return ValueOrder::NotAdjacent;
3389 }
3390
3391 int bits_per_store = memory_size * 8;
3392 if (base_n1 != base_n2 ||
3393 abs(shift_n1 - shift_n2) != bits_per_store ||
3394 shift_n1 % bits_per_store != 0) {
3395 // Values are not adjacent
3396 return ValueOrder::NotAdjacent;
3397 }
3398
3399 // Detect value order
3400 #ifdef VM_LITTLE_ENDIAN
3401 return shift_n1 < shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3402 : ValueOrder::Reverse; // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3403 #else
3404 return shift_n1 > shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3405 : ValueOrder::Reverse; // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3406 #endif
3407 }
3408
3409 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3410 ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size);
3411
3412 switch (input_value_order) {
3413 case ValueOrder::NotAdjacent:
3414 return false;
3415 case ValueOrder::Reverse:
3416 if (memory_size != 1 ||
3417 !Matcher::match_rule_supported(Op_ReverseBytesS) ||
3418 !Matcher::match_rule_supported(Op_ReverseBytesI) ||
3419 !Matcher::match_rule_supported(Op_ReverseBytesL)) {
3420 // ReverseBytes are not supported by platform
3421 return false;
3422 }
3423 // fall-through.
3424 case ValueOrder::Const:
3425 case ValueOrder::Platform:
3426 if (_value_order == ValueOrder::Unknown) {
3427 // Initial state is Unknown, and we find a valid input value order
3428 return true;
3429 }
3430 // The value order can not be changed
3431 return _value_order == input_value_order;
3432 case ValueOrder::Unknown:
3433 default:
3434 ShouldNotReachHere();
3435 }
3436 return false;
3437 }
3438
3439 // Detect pattern: n = base_out >> shift_out
3440 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) {
3441 assert(n != nullptr, "precondition");
3442
3443 int opc = n->Opcode();
3444 if (opc == Op_ConvL2I) {
3445 n = n->in(1);
3446 opc = n->Opcode();
3447 }
3448
3449 if ((opc == Op_RShiftI ||
3450 opc == Op_RShiftL ||
3451 opc == Op_URShiftI ||
3452 opc == Op_URShiftL) &&
3453 n->in(2)->is_ConI()) {
3454 base_out = n->in(1);
3455 shift_out = n->in(2)->get_int();
3456 // The shift must be positive:
3457 return shift_out >= 0;
3458 }
3459
3460 if (phase->type(n)->isa_int() != nullptr ||
3461 phase->type(n)->isa_long() != nullptr) {
3462 // (base >> 0)
3463 base_out = n;
3464 shift_out = 0;
3465 return true;
3466 }
3467 return false;
3468 }
3469
3470 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3471 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3472 assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3473
3474 Node* ctrl_use = use_store->in(MemNode::Control);
3475 Node* ctrl_def = def_store->in(MemNode::Control);
3476 if (ctrl_use == nullptr || ctrl_def == nullptr) {
3477 return CFGStatus::Failure;
3478 }
3479
3480 if (ctrl_use == ctrl_def) {
3481 // Same ctrl -> no RangeCheck in between.
3482 // Check: use_store must be the only use of def_store.
3483 if (def_store->outcnt() > 1) {
3484 return CFGStatus::Failure;
3485 }
3486 return CFGStatus::SuccessNoRangeCheck;
3487 }
3488
3489 // Different ctrl -> could have RangeCheck in between.
3490 // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3491 // 2. ctrl separated by RangeCheck.
3492 if (def_store->outcnt() != 2) {
3493 return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3494 }
3495 int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3496 Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3497 if (merge_mem == nullptr ||
3498 merge_mem->outcnt() != 1) {
3499 return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3500 }
3501 if (!ctrl_use->is_IfProj() ||
3502 !ctrl_use->in(0)->is_RangeCheck() ||
3503 ctrl_use->in(0)->outcnt() != 2) {
3504 return CFGStatus::Failure; // Not RangeCheck.
3505 }
3506 IfProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3507 Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3508 if (trap != merge_mem->unique_out() ||
3509 ctrl_use->in(0)->in(0) != ctrl_def) {
3510 return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3511 }
3512
3513 return CFGStatus::SuccessWithRangeCheck;
3514 }
3515
3516 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const {
3517 Status status_use = find_use_store(def_store);
3518 StoreNode* use_store = status_use.found_store();
3519 if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3520 return Status::make_failure();
3521 }
3522 return status_use;
3523 }
3524
3525 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const {
3526 Status status_def = find_def_store(use_store);
3527 StoreNode* def_store = status_def.found_store();
3528 if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3529 return Status::make_failure();
3530 }
3531 return status_def;
3532 }
3533
3534 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const {
3535 Status status_use = find_use_store_unidirectional(def_store);
3536
3537 #ifdef ASSERT
3538 StoreNode* use_store = status_use.found_store();
3539 if (use_store != nullptr) {
3540 Status status_def = find_def_store_unidirectional(use_store);
3541 assert(status_def.found_store() == def_store &&
3542 status_def.found_range_check() == status_use.found_range_check(),
3543 "find_use_store and find_def_store must be symmetric");
3544 }
3545 #endif
3546
3547 return status_use;
3548 }
3549
3550 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const {
3551 Status status_def = find_def_store_unidirectional(use_store);
3552
3553 #ifdef ASSERT
3554 StoreNode* def_store = status_def.found_store();
3555 if (def_store != nullptr) {
3556 Status status_use = find_use_store_unidirectional(def_store);
3557 assert(status_use.found_store() == use_store &&
3558 status_use.found_range_check() == status_def.found_range_check(),
3559 "find_use_store and find_def_store must be symmetric");
3560 }
3561 #endif
3562
3563 return status_def;
3564 }
3565
3566 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3567 assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3568
3569 for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3570 StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3571 if (is_compatible_store(use_store)) {
3572 return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3573 }
3574 }
3575
3576 return Status::make_failure();
3577 }
3578
3579 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3580 assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3581
3582 StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3583 if (!is_compatible_store(def_store)) {
3584 return Status::make_failure();
3585 }
3586
3587 return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3588 }
3589
3590 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const {
3591 // The merged store can be at most 8 bytes.
3592 const uint merge_list_max_size = 8 / _store->memory_size();
3593 assert(merge_list_max_size >= 2 &&
3594 merge_list_max_size <= 8 &&
3595 is_power_of_2(merge_list_max_size),
3596 "must be 2, 4 or 8");
3597
3598 // Traverse up the chain of adjacent def stores.
3599 StoreNode* current = _store;
3600 merge_list.push(current);
3601 while (current != nullptr && merge_list.size() < merge_list_max_size) {
3602 Status status = find_adjacent_def_store(current);
3603 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); })
3604
3605 current = status.found_store();
3606 if (current != nullptr) {
3607 merge_list.push(current);
3608
3609 // We can have at most one RangeCheck.
3610 if (status.found_range_check()) {
3611 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); })
3612 break;
3613 }
3614 }
3615 }
3616
3617 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); })
3618
3619 // Truncate the merge_list to a power of 2.
3620 const uint pow2size = round_down_power_of_2(merge_list.size());
3621 assert(pow2size >= 2, "must be merging at least 2 stores");
3622 while (merge_list.size() > pow2size) { merge_list.pop(); }
3623
3624 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); })
3625 }
3626
3627 // Merge the input values of the smaller stores to a single larger input value.
3628 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) {
3629 int new_memory_size = _store->memory_size() * merge_list.size();
3630 Node* first = merge_list.at(merge_list.size()-1);
3631 Node* merged_input_value = nullptr;
3632 if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3633 assert(_value_order == ValueOrder::Const, "must match");
3634 // Pattern: [ConI, ConI, ...] -> new constant
3635 jlong con = 0;
3636 jlong bits_per_store = _store->memory_size() * 8;
3637 jlong mask = (((jlong)1) << bits_per_store) - 1;
3638 for (uint i = 0; i < merge_list.size(); i++) {
3639 jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3640 #ifdef VM_LITTLE_ENDIAN
3641 con = con << bits_per_store;
3642 con = con | (mask & con_i);
3643 #else // VM_LITTLE_ENDIAN
3644 con_i = (mask & con_i) << (i * bits_per_store);
3645 con = con | con_i;
3646 #endif // VM_LITTLE_ENDIAN
3647 }
3648 merged_input_value = _phase->longcon(con);
3649 } else {
3650 assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match");
3651 // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3652 // | |
3653 // _store first
3654 //
3655 Node* hi = _store->in(MemNode::ValueIn);
3656 Node* lo = first->in(MemNode::ValueIn);
3657 #ifndef VM_LITTLE_ENDIAN
3658 // `_store` and `first` are swapped in the diagram above
3659 swap(hi, lo);
3660 #endif // !VM_LITTLE_ENDIAN
3661 if (_value_order == ValueOrder::Reverse) {
3662 swap(hi, lo);
3663 }
3664 Node const* hi_base;
3665 jint hi_shift;
3666 merged_input_value = lo;
3667 bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase);
3668 assert(is_true, "must detect con RShift");
3669 if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3670 // look through
3671 merged_input_value = merged_input_value->in(1);
3672 }
3673 if (merged_input_value != hi_base) {
3674 // merged_input_value is not the base
3675 return nullptr;
3676 }
3677 }
3678
3679 if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3680 // Example:
3681 //
3682 // long base = ...;
3683 // a[0] = (byte)(base >> 0);
3684 // a[1] = (byte)(base >> 8);
3685 //
3686 merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3687 }
3688
3689 assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3690 (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3691 "merged_input_value is either int or long, and new_memory_size is small enough");
3692
3693 if (_value_order == ValueOrder::Reverse) {
3694 assert(_store->memory_size() == 1, "only implemented for bytes");
3695 if (new_memory_size == 8) {
3696 merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value));
3697 } else if (new_memory_size == 4) {
3698 merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value));
3699 } else {
3700 assert(new_memory_size == 2, "sanity check");
3701 merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value));
3702 }
3703 }
3704 return merged_input_value;
3705 }
3706
3707 // //
3708 // first_ctrl first_mem first_adr first_ctrl first_mem first_adr //
3709 // | | | | | | //
3710 // | | | | +---------------+ | //
3711 // | | | | | | | //
3712 // | | +---------+ | | +---------------+ //
3713 // | | | | | | | | //
3714 // +--------------+ | | v1 +------------------------------+ | | v1 //
3715 // | | | | | | | | | | | | //
3716 // RangeCheck first_store RangeCheck | | first_store //
3717 // | | | | | | | //
3718 // last_ctrl | +----> unc_trap last_ctrl | | +----> unc_trap //
3719 // | | ===> | | | //
3720 // +--------------+ | a2 v2 | | | //
3721 // | | | | | | | | //
3722 // | second_store | | | //
3723 // | | | | | [v1 v2 ... vn] //
3724 // ... ... | | | | //
3725 // | | | | | v //
3726 // +--------------+ | an vn +--------------+ | | merged_input_value //
3727 // | | | | | | | | //
3728 // last_store (= _store) merged_store //
3729 // //
3730 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3731 Node* first_store = merge_list.at(merge_list.size()-1);
3732 Node* last_ctrl = _store->in(MemNode::Control); // after (optional) RangeCheck
3733 Node* first_mem = first_store->in(MemNode::Memory);
3734 Node* first_adr = first_store->in(MemNode::Address);
3735
3736 const TypePtr* new_adr_type = _store->adr_type();
3737
3738 int new_memory_size = _store->memory_size() * merge_list.size();
3739 BasicType bt = T_ILLEGAL;
3740 switch (new_memory_size) {
3741 case 2: bt = T_SHORT; break;
3742 case 4: bt = T_INT; break;
3743 case 8: bt = T_LONG; break;
3744 }
3745
3746 StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3747 new_adr_type, merged_input_value, bt, MemNode::unordered);
3748
3749 // Marking the store mismatched is sufficient to prevent reordering, since array stores
3750 // are all on the same slice. Hence, we need no barriers.
3751 merged_store->set_mismatched_access();
3752
3753 // Constants above may now also be be packed -> put candidate on worklist
3754 _phase->is_IterGVN()->_worklist.push(first_mem);
3755
3756 return merged_store;
3757 }
3758
3759 #ifndef PRODUCT
3760 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3761 stringStream ss;
3762 ss.print_cr("[TraceMergeStores]: Replace");
3763 for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3764 merge_list.at(i)->dump("\n", false, &ss);
3765 }
3766 ss.print_cr("[TraceMergeStores]: with");
3767 merged_input_value->dump("\n", false, &ss);
3768 merged_store->dump("\n", false, &ss);
3769 tty->print("%s", ss.as_string());
3770 }
3771 #endif
3772
3773 //------------------------------Ideal------------------------------------------
3774 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3775 // When a store immediately follows a relevant allocation/initialization,
3776 // try to capture it into the initialization, or hoist it above.
3777 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3778 Node* p = MemNode::Ideal_common(phase, can_reshape);
3779 if (p) return (p == NodeSentinel) ? nullptr : p;
3780
3781 Node* mem = in(MemNode::Memory);
3782 Node* address = in(MemNode::Address);
3783 Node* value = in(MemNode::ValueIn);
3784 // Back-to-back stores to same address? Fold em up. Generally
3785 // unsafe if I have intervening uses...
3786 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) {
3787 Node* st = mem;
3788 // If Store 'st' has more than one use, we cannot fold 'st' away.
3789 // For example, 'st' might be the final state at a conditional
3790 // return. Or, 'st' might be used by some node which is live at
3791 // the same time 'st' is live, which might be unschedulable. So,
3792 // require exactly ONE user until such time as we clone 'mem' for
3793 // each of 'mem's uses (thus making the exactly-1-user-rule hold
3794 // true).
3795 while (st->is_Store() && st->outcnt() == 1) {
3796 // Looking at a dead closed cycle of memory?
3797 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3798 assert(Opcode() == st->Opcode() ||
3799 st->Opcode() == Op_StoreVector ||
3800 Opcode() == Op_StoreVector ||
3801 st->Opcode() == Op_StoreVectorScatter ||
3802 Opcode() == Op_StoreVectorScatter ||
3803 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3804 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3805 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3806 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
3807 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3808 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3809
3810 if (st->in(MemNode::Address)->eqv_uncast(address) &&
3811 st->as_Store()->memory_size() <= this->memory_size()) {
3812 Node* use = st->raw_out(0);
3813 if (phase->is_IterGVN()) {
3814 phase->is_IterGVN()->rehash_node_delayed(use);
3815 }
3816 // It's OK to do this in the parser, since DU info is always accurate,
3817 // and the parser always refers to nodes via SafePointNode maps.
3818 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3819 return this;
3820 }
3821 st = st->in(MemNode::Memory);
3822 }
3823 }
3824
3825
3826 // Capture an unaliased, unconditional, simple store into an initializer.
3827 // Or, if it is independent of the allocation, hoist it above the allocation.
3828 if (ReduceFieldZeroing && /*can_reshape &&*/
3829 mem->is_Proj() && mem->in(0)->is_Initialize()) {
3830 InitializeNode* init = mem->in(0)->as_Initialize();
3831 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3832 if (offset > 0) {
3833 Node* moved = init->capture_store(this, offset, phase, can_reshape);
3834 // If the InitializeNode captured me, it made a raw copy of me,
3835 // and I need to disappear.
3836 if (moved != nullptr) {
3837 // %%% hack to ensure that Ideal returns a new node:
3838 mem = MergeMemNode::make(mem);
3839 return mem; // fold me away
3840 }
3841 }
3842 }
3843
3844 // Fold reinterpret cast into memory operation:
3845 // StoreX mem (MoveY2X v) => StoreY mem v
3846 if (value->is_Move()) {
3847 const Type* vt = value->in(1)->bottom_type();
3848 if (has_reinterpret_variant(vt)) {
3849 if (phase->C->post_loop_opts_phase()) {
3850 return convert_to_reinterpret_store(*phase, value->in(1), vt);
3851 } else {
3852 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3853 }
3854 }
3855 }
3856
3857 if (MergeStores && UseUnalignedAccesses) {
3858 if (phase->C->merge_stores_phase()) {
3859 MergePrimitiveStores merge(phase, this);
3860 Node* progress = merge.run();
3861 if (progress != nullptr) { return progress; }
3862 } else {
3863 // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during
3864 // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between
3865 // the stores, and we merge the wrong sequence of stores.
3866 // Example:
3867 // StoreI RangeCheck StoreI StoreI RangeCheck StoreI
3868 // Apply MergeStores:
3869 // StoreI RangeCheck [ StoreL ] RangeCheck StoreI
3870 // Remove more RangeChecks:
3871 // StoreI [ StoreL ] StoreI
3872 // But now it would have been better to do this instead:
3873 // [ StoreL ] [ StoreL ]
3874 phase->C->record_for_merge_stores_igvn(this);
3875 }
3876 }
3877
3878 return nullptr; // No further progress
3879 }
3880
3881 //------------------------------Value-----------------------------------------
3882 const Type* StoreNode::Value(PhaseGVN* phase) const {
3883 // Either input is TOP ==> the result is TOP
3884 const Type *t1 = phase->type( in(MemNode::Memory) );
3885 if( t1 == Type::TOP ) return Type::TOP;
3886 const Type *t2 = phase->type( in(MemNode::Address) );
3887 if( t2 == Type::TOP ) return Type::TOP;
3888 const Type *t3 = phase->type( in(MemNode::ValueIn) );
3889 if( t3 == Type::TOP ) return Type::TOP;
3890 return Type::MEMORY;
3891 }
3892
3893 //------------------------------Identity---------------------------------------
3894 // Remove redundant stores:
3895 // Store(m, p, Load(m, p)) changes to m.
3896 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3897 Node* StoreNode::Identity(PhaseGVN* phase) {
3898 Node* mem = in(MemNode::Memory);
3899 Node* adr = in(MemNode::Address);
3900 Node* val = in(MemNode::ValueIn);
3901
3902 Node* result = this;
3903
3904 // Load then Store? Then the Store is useless
3905 if (val->is_Load() &&
3906 val->in(MemNode::Address)->eqv_uncast(adr) &&
3907 val->in(MemNode::Memory )->eqv_uncast(mem) &&
3908 val->as_Load()->store_Opcode() == Opcode()) {
3909 if (!is_StoreVector()) {
3910 result = mem;
3911 } else if (Opcode() == Op_StoreVector && val->Opcode() == Op_LoadVector &&
3912 as_StoreVector()->vect_type() == val->as_LoadVector()->vect_type()) {
3913 // Ensure both are not masked accesses or gathers/scatters and vector types are the same
3914 result = mem;
3915 }
3916 }
3917
3918 // Two stores in a row of the same value?
3919 if (result == this &&
3920 mem->is_Store() &&
3921 mem->in(MemNode::Address)->eqv_uncast(adr) &&
3922 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3923 mem->Opcode() == Opcode()) {
3924 if (!is_StoreVector()) {
3925 result = mem;
3926 } else {
3927 const StoreVectorNode* store_vector = as_StoreVector();
3928 const StoreVectorNode* mem_vector = mem->as_StoreVector();
3929 const Node* store_indices = store_vector->indices();
3930 const Node* mem_indices = mem_vector->indices();
3931 const Node* store_mask = store_vector->mask();
3932 const Node* mem_mask = mem_vector->mask();
3933 // Ensure types, indices, and masks match
3934 if (store_vector->vect_type() == mem_vector->vect_type() &&
3935 ((store_indices == nullptr) == (mem_indices == nullptr) &&
3936 (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3937 ((store_mask == nullptr) == (mem_mask == nullptr) &&
3938 (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3939 result = mem;
3940 }
3941 }
3942 }
3943
3944 // Store of zero anywhere into a freshly-allocated object?
3945 // Then the store is useless.
3946 // (It must already have been captured by the InitializeNode.)
3947 if (result == this && ReduceFieldZeroing) {
3948 // a newly allocated object is already all-zeroes everywhere
3949 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
3950 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::InitValue) == val)) {
3951 result = mem;
3952 }
3953
3954 if (result == this && phase->type(val)->is_zero_type()) {
3955 // the store may also apply to zero-bits in an earlier object
3956 Node* prev_mem = find_previous_store(phase);
3957 // Steps (a), (b): Walk past independent stores to find an exact match.
3958 if (prev_mem != nullptr) {
3959 if (prev_mem->is_top()) {
3960 // find_previous_store returns top when the access is dead
3961 return prev_mem;
3962 }
3963 Node* prev_val = can_see_stored_value(prev_mem, phase);
3964 if (prev_val != nullptr && prev_val == val) {
3965 // prev_val and val might differ by a cast; it would be good
3966 // to keep the more informative of the two.
3967 result = mem;
3968 }
3969 }
3970 }
3971 }
3972
3973 PhaseIterGVN* igvn = phase->is_IterGVN();
3974 if (result != this && igvn != nullptr) {
3975 MemBarNode* trailing = trailing_membar();
3976 if (trailing != nullptr) {
3977 #ifdef ASSERT
3978 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3979 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3980 #endif
3981 trailing->remove(igvn);
3982 }
3983 }
3984
3985 return result;
3986 }
3987
3988 //------------------------------match_edge-------------------------------------
3989 // Do we Match on this edge index or not? Match only memory & value
3990 uint StoreNode::match_edge(uint idx) const {
3991 return idx == MemNode::Address || idx == MemNode::ValueIn;
3992 }
3993
3994 //------------------------------cmp--------------------------------------------
3995 // Do not common stores up together. They generally have to be split
3996 // back up anyways, so do not bother.
3997 bool StoreNode::cmp( const Node &n ) const {
3998 return (&n == this); // Always fail except on self
3999 }
4000
4001 //------------------------------Ideal_masked_input-----------------------------
4002 // Check for a useless mask before a partial-word store
4003 // (StoreB ... (AndI valIn conIa) )
4004 // If (conIa & mask == mask) this simplifies to
4005 // (StoreB ... (valIn) )
4006 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
4007 Node *val = in(MemNode::ValueIn);
4008 if( val->Opcode() == Op_AndI ) {
4009 const TypeInt *t = phase->type( val->in(2) )->isa_int();
4010 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
4011 set_req_X(MemNode::ValueIn, val->in(1), phase);
4012 return this;
4013 }
4014 }
4015 return nullptr;
4016 }
4017
4018
4019 //------------------------------Ideal_sign_extended_input----------------------
4020 // Check for useless sign-extension before a partial-word store
4021 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
4022 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to
4023 // (StoreB ... (v))
4024 // If (conIL > conIR) under some conditions, it can be simplified into
4025 // (StoreB ... (LShiftI _ v (conIL - conIR)))
4026 // This case happens when the value of the store was itself a left shift, that
4027 // gets merged into the inner left shift of the sign-extension. For instance,
4028 // if we have
4029 // array_of_shorts[0] = (short)(v << 2)
4030 // We get a structure such as:
4031 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16))
4032 // that is simplified into
4033 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)).
4034 // It is thus useful to handle cases where conIL > conIR. But this simplification
4035 // does not always hold. Let's see in which cases it's valid.
4036 //
4037 // Let's assume we have the following 32 bits integer v:
4038 // +----------------------------------+
4039 // | v[0..31] |
4040 // +----------------------------------+
4041 // 31 0
4042 // that will be stuffed in 8 bits byte after a shift left and a shift right of
4043 // potentially different magnitudes.
4044 // We denote num_rejected_bits the number of bits of the discarded part. In this
4045 // case, num_rejected_bits == 24.
4046 //
4047 // Statement (proved further below in case analysis):
4048 // Given:
4049 // - 0 <= conIL < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
4050 // - 0 <= conIR < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
4051 // - conIL >= conIR
4052 // - num_rejected_bits >= conIR
4053 // Then this form:
4054 // (RShiftI _ (LShiftI _ v conIL) conIR)
4055 // can be replaced with this form:
4056 // (LShiftI _ v (conIL-conIR))
4057 //
4058 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte)
4059 // have to be correct, as the higher bits are rejected / truncated by the store.
4060 //
4061 // The hypotheses
4062 // 0 <= conIL < BitsPerJavaInteger
4063 // 0 <= conIR < BitsPerJavaInteger
4064 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed,
4065 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent
4066 // to v << 1).
4067 //
4068 //
4069 // If you don't like case analysis, jump after the conclusion.
4070 // ### Case 1 : conIL == conIR
4071 // ###### Case 1.1: conIL == conIR == num_rejected_bits
4072 // If we do the shift left then right by 24 bits, we get:
4073 // after: v << 24
4074 // +---------+------------------------+
4075 // | v[0..7] | 0 |
4076 // +---------+------------------------+
4077 // 31 24 23 0
4078 // after: (v << 24) >> 24
4079 // +------------------------+---------+
4080 // | sign bit | v[0..7] |
4081 // +------------------------+---------+
4082 // 31 8 7 0
4083 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the
4084 // result) are the same before and after, so, indeed, simplifying is correct.
4085
4086 // ###### Case 1.2: conIL == conIR < num_rejected_bits
4087 // If we do the shift left then right by 22 bits, we get:
4088 // after: v << 22
4089 // +---------+------------------------+
4090 // | v[0..9] | 0 |
4091 // +---------+------------------------+
4092 // 31 22 21 0
4093 // after: (v << 22) >> 22
4094 // +------------------------+---------+
4095 // | sign bit | v[0..9] |
4096 // +------------------------+---------+
4097 // 31 10 9 0
4098 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still
4099 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is
4100 // still correct.
4101
4102 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits
4103 // If we do the shift left then right by 26 bits, we get:
4104 // after: v << 26
4105 // +---------+------------------------+
4106 // | v[0..5] | 0 |
4107 // +---------+------------------------+
4108 // 31 26 25 0
4109 // after: (v << 26) >> 26
4110 // +------------------------+---------+
4111 // | sign bit | v[0..5] |
4112 // +------------------------+---------+
4113 // 31 6 5 0
4114 // The non-rejected bits are made of
4115 // - 0-5 => the bits 0 to 5 of v
4116 // - 6-7 => the sign bit of v[0..5] (that is v[5])
4117 // Simplifying this as v is not correct.
4118 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1
4119 //
4120 // ### Case 2: conIL > conIR
4121 // ###### Case 2.1: num_rejected_bits == conIR
4122 // We take conIL == 26 for this example.
4123 // after: v << 26
4124 // +---------+------------------------+
4125 // | v[0..5] | 0 |
4126 // +---------+------------------------+
4127 // 31 26 25 0
4128 // after: (v << 26) >> 24
4129 // +------------------+---------+-----+
4130 // | sign bit | v[0..5] | 0 |
4131 // +------------------+---------+-----+
4132 // 31 8 7 2 1 0
4133 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR).
4134 // The bits 6 and 7 of v have been thrown away after the shift left.
4135 // The simplification is still correct.
4136 //
4137 // ###### Case 2.2: num_rejected_bits > conIR.
4138 // Let's say conIL == 26 and conIR == 22.
4139 // after: v << 26
4140 // +---------+------------------------+
4141 // | v[0..5] | 0 |
4142 // +---------+------------------------+
4143 // 31 26 25 0
4144 // after: (v << 26) >> 22
4145 // +------------------+---------+-----+
4146 // | sign bit | v[0..5] | 0 |
4147 // +------------------+---------+-----+
4148 // 31 10 9 4 3 0
4149 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)):
4150 // - 0-3 => 0
4151 // - 4-7 => bits 0 to 3 of v
4152 // The simplification is still correct.
4153 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't
4154 // matter as they are not in the 8 lower bits: they will be cut out by the store.
4155 //
4156 // ###### But! Case 2.3: num_rejected_bits < conIR.
4157 // Let's see that this case is not as easy to simplify.
4158 // Let's say conIL == 28 and conIR == 26.
4159 // after: v << 28
4160 // +---------+------------------------+
4161 // | v[0..3] | 0 |
4162 // +---------+------------------------+
4163 // 31 28 27 0
4164 // after: (v << 28) >> 26
4165 // +------------------+---------+-----+
4166 // | sign bit | v[0..3] | 0 |
4167 // +------------------+---------+-----+
4168 // 31 6 5 2 1 0
4169 // The non-rejected bits are made of
4170 // - 0-1 => 0
4171 // - 2-5 => the bits 0 to 3 of v
4172 // - 6-7 => the sign bit of v[0..3] (that is v[3])
4173 // Simplifying this as (v << 2) is not correct.
4174 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2.
4175 //
4176 // ### Conclusion:
4177 // Our hypotheses are indeed sufficient:
4178 // - 0 <= conIL < BitsPerJavaInteger
4179 // - 0 <= conIR < BitsPerJavaInteger
4180 // - conIL >= conIR
4181 // - num_rejected_bits >= conIR
4182 //
4183 // ### A rationale without case analysis:
4184 // After the shift left, conIL upper bits of v are discarded and conIL lower bit
4185 // zeroes are added. After the shift right, conIR lower bits of the previous result
4186 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during
4187 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But
4188 // the point of the simplification is to get an expression of the form
4189 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the
4190 // simplification is not correct if conIL < conIR.
4191 //
4192 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the
4193 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If
4194 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will
4195 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to
4196 // (v << (conIL-conIR)) if conIR > num_rejected_bits.
4197 //
4198 // We do not treat the case conIL < conIR here since the point of this function is
4199 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need
4200 // of treating conIL > conIR comes from the cases where the sign-extended value is
4201 // also left-shift expression. Computing the sign-extension of a right-shift expression
4202 // doesn't yield a situation such as
4203 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
4204 // where conIL < conIR.
4205 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) {
4206 Node* shr = in(MemNode::ValueIn);
4207 if (shr->Opcode() == Op_RShiftI) {
4208 const TypeInt* conIR = phase->type(shr->in(2))->isa_int();
4209 if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) {
4210 Node* shl = shr->in(1);
4211 if (shl->Opcode() == Op_LShiftI) {
4212 const TypeInt* conIL = phase->type(shl->in(2))->isa_int();
4213 if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) {
4214 if (conIL->get_con() == conIR->get_con()) {
4215 set_req_X(MemNode::ValueIn, shl->in(1), phase);
4216 return this;
4217 }
4218 if (conIL->get_con() > conIR->get_con()) {
4219 Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con())));
4220 set_req_X(MemNode::ValueIn, new_shl, phase);
4221 return this;
4222 }
4223 }
4224 }
4225 }
4226 }
4227 return nullptr;
4228 }
4229
4230 //------------------------------value_never_loaded-----------------------------------
4231 // Determine whether there are any possible loads of the value stored.
4232 // For simplicity, we actually check if there are any loads from the
4233 // address stored to, not just for loads of the value stored by this node.
4234 //
4235 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
4236 Node *adr = in(Address);
4237 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
4238 if (adr_oop == nullptr)
4239 return false;
4240 if (!adr_oop->is_known_instance_field())
4241 return false; // if not a distinct instance, there may be aliases of the address
4242 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
4243 Node *use = adr->fast_out(i);
4244 if (use->is_Load() || use->is_LoadStore()) {
4245 return false;
4246 }
4247 }
4248 return true;
4249 }
4250
4251 MemBarNode* StoreNode::trailing_membar() const {
4252 if (is_release()) {
4253 MemBarNode* trailing_mb = nullptr;
4254 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4255 Node* u = fast_out(i);
4256 if (u->is_MemBar()) {
4257 if (u->as_MemBar()->trailing_store()) {
4258 assert(u->Opcode() == Op_MemBarVolatile, "");
4259 assert(trailing_mb == nullptr, "only one");
4260 trailing_mb = u->as_MemBar();
4261 #ifdef ASSERT
4262 Node* leading = u->as_MemBar()->leading_membar();
4263 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4264 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
4265 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
4266 #endif
4267 } else {
4268 assert(u->as_MemBar()->standalone(), "");
4269 }
4270 }
4271 }
4272 return trailing_mb;
4273 }
4274 return nullptr;
4275 }
4276
4277
4278 //=============================================================================
4279 //------------------------------Ideal------------------------------------------
4280 // If the store is from an AND mask that leaves the low bits untouched, then
4281 // we can skip the AND operation. If the store is from a sign-extension
4282 // (a left shift, then right shift) we can skip both.
4283 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
4284 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
4285 if( progress != nullptr ) return progress;
4286
4287 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
4288 if( progress != nullptr ) return progress;
4289
4290 // Finally check the default case
4291 return StoreNode::Ideal(phase, can_reshape);
4292 }
4293
4294 //=============================================================================
4295 //------------------------------Ideal------------------------------------------
4296 // If the store is from an AND mask that leaves the low bits untouched, then
4297 // we can skip the AND operation
4298 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
4299 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
4300 if( progress != nullptr ) return progress;
4301
4302 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
4303 if( progress != nullptr ) return progress;
4304
4305 // Finally check the default case
4306 return StoreNode::Ideal(phase, can_reshape);
4307 }
4308
4309 //=============================================================================
4310 //----------------------------------SCMemProjNode------------------------------
4311 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
4312 {
4313 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
4314 return Type::TOP;
4315 }
4316 return bottom_type();
4317 }
4318
4319 //=============================================================================
4320 //----------------------------------LoadStoreNode------------------------------
4321 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
4322 : Node(required),
4323 _type(rt),
4324 _barrier_data(0)
4325 {
4326 init_req(MemNode::Control, c );
4327 init_req(MemNode::Memory , mem);
4328 init_req(MemNode::Address, adr);
4329 init_req(MemNode::ValueIn, val);
4330 init_class_id(Class_LoadStore);
4331 DEBUG_ONLY(_adr_type = at; adr_type();)
4332 }
4333
4334 //------------------------------Value-----------------------------------------
4335 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
4336 // Either input is TOP ==> the result is TOP
4337 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
4338 return Type::TOP;
4339 }
4340 const Type* t = phase->type(in(MemNode::Memory));
4341 if (t == Type::TOP) {
4342 return Type::TOP;
4343 }
4344 t = phase->type(in(MemNode::Address));
4345 if (t == Type::TOP) {
4346 return Type::TOP;
4347 }
4348 t = phase->type(in(MemNode::ValueIn));
4349 if (t == Type::TOP) {
4350 return Type::TOP;
4351 }
4352 return bottom_type();
4353 }
4354
4355 const TypePtr* LoadStoreNode::adr_type() const {
4356 const TypePtr* cross_check = DEBUG_ONLY(_adr_type) NOT_DEBUG(nullptr);
4357 return MemNode::calculate_adr_type(in(MemNode::Address)->bottom_type(), cross_check);
4358 }
4359
4360 uint LoadStoreNode::ideal_reg() const {
4361 return _type->ideal_reg();
4362 }
4363
4364 // This method conservatively checks if the result of a LoadStoreNode is
4365 // used, that is, if it returns true, then it is definitely the case that
4366 // the result of the node is not needed.
4367 // For example, GetAndAdd can be matched into a lock_add instead of a
4368 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
4369 bool LoadStoreNode::result_not_used() const {
4370 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4371 Node *x = fast_out(i);
4372 if (x->Opcode() == Op_SCMemProj || x->is_ReachabilityFence()) {
4373 continue;
4374 }
4375 if (x->bottom_type() == TypeTuple::MEMBAR &&
4376 !x->is_Call() &&
4377 x->Opcode() != Op_Blackhole) {
4378 continue;
4379 }
4380 return false;
4381 }
4382 return true;
4383 }
4384
4385 MemBarNode* LoadStoreNode::trailing_membar() const {
4386 MemBarNode* trailing = nullptr;
4387 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4388 Node* u = fast_out(i);
4389 if (u->is_MemBar()) {
4390 if (u->as_MemBar()->trailing_load_store()) {
4391 assert(u->Opcode() == Op_MemBarAcquire, "");
4392 assert(trailing == nullptr, "only one");
4393 trailing = u->as_MemBar();
4394 #ifdef ASSERT
4395 Node* leading = trailing->leading_membar();
4396 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4397 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
4398 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
4399 #endif
4400 } else {
4401 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
4402 }
4403 }
4404 }
4405
4406 return trailing;
4407 }
4408
4409 uint LoadStoreNode::size_of() const { return sizeof(*this); }
4410
4411 //=============================================================================
4412 //----------------------------------LoadStoreConditionalNode--------------------
4413 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
4414 init_req(ExpectedIn, ex );
4415 }
4416
4417 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
4418 // Either input is TOP ==> the result is TOP
4419 const Type* t = phase->type(in(ExpectedIn));
4420 if (t == Type::TOP) {
4421 return Type::TOP;
4422 }
4423 return LoadStoreNode::Value(phase);
4424 }
4425
4426 //=============================================================================
4427 //-------------------------------adr_type--------------------------------------
4428 const TypePtr* ClearArrayNode::adr_type() const {
4429 Node *adr = in(3);
4430 if (adr == nullptr) return nullptr; // node is dead
4431 return MemNode::calculate_adr_type(adr->bottom_type());
4432 }
4433
4434 //------------------------------match_edge-------------------------------------
4435 // Do we Match on this edge index or not? Do not match memory
4436 uint ClearArrayNode::match_edge(uint idx) const {
4437 return idx > 1;
4438 }
4439
4440 //------------------------------Identity---------------------------------------
4441 // Clearing a zero length array does nothing
4442 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
4443 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
4444 }
4445
4446 //------------------------------Idealize---------------------------------------
4447 // Clearing a short array is faster with stores
4448 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4449 // Already know this is a large node, do not try to ideal it
4450 if (_is_large) return nullptr;
4451
4452 const int unit = BytesPerLong;
4453 const TypeX* t = phase->type(in(2))->isa_intptr_t();
4454 if (!t) return nullptr;
4455 if (!t->is_con()) return nullptr;
4456 intptr_t raw_count = t->get_con();
4457 intptr_t size = raw_count;
4458 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
4459 // Clearing nothing uses the Identity call.
4460 // Negative clears are possible on dead ClearArrays
4461 // (see jck test stmt114.stmt11402.val).
4462 if (size <= 0 || size % unit != 0) return nullptr;
4463 intptr_t count = size / unit;
4464 // Length too long; communicate this to matchers and assemblers.
4465 // Assemblers are responsible to produce fast hardware clears for it.
4466 if (size > InitArrayShortSize) {
4467 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
4468 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
4469 return nullptr;
4470 }
4471 if (!IdealizeClearArrayNode) return nullptr;
4472 Node *mem = in(1);
4473 if( phase->type(mem)==Type::TOP ) return nullptr;
4474 Node *adr = in(3);
4475 const Type* at = phase->type(adr);
4476 if( at==Type::TOP ) return nullptr;
4477 const TypePtr* atp = at->isa_ptr();
4478 // adjust atp to be the correct array element address type
4479 if (atp == nullptr) atp = TypePtr::BOTTOM;
4480 else atp = atp->add_offset(Type::OffsetBot);
4481 // Get base for derived pointer purposes
4482 if( adr->Opcode() != Op_AddP ) Unimplemented();
4483 Node *base = adr->in(1);
4484
4485 Node *val = in(4);
4486 Node *off = phase->MakeConX(BytesPerLong);
4487 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
4488 count--;
4489 while (count--) {
4490 mem = phase->transform(mem);
4491 adr = phase->transform(AddPNode::make_with_base(base,adr,off));
4492 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
4493 }
4494 return mem;
4495 }
4496
4497 //----------------------------step_through----------------------------------
4498 // Return allocation input memory edge if it is different instance
4499 // or itself if it is the one we are looking for.
4500 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
4501 Node* n = *np;
4502 assert(n->is_ClearArray(), "sanity");
4503 intptr_t offset;
4504 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
4505 // This method is called only before Allocate nodes are expanded
4506 // during macro nodes expansion. Before that ClearArray nodes are
4507 // only generated in PhaseMacroExpand::generate_arraycopy() (before
4508 // Allocate nodes are expanded) which follows allocations.
4509 assert(alloc != nullptr, "should have allocation");
4510 if (alloc->_idx == instance_id) {
4511 // Can not bypass initialization of the instance we are looking for.
4512 return false;
4513 }
4514 // Otherwise skip it.
4515 InitializeNode* init = alloc->initialization();
4516 if (init != nullptr)
4517 *np = init->in(TypeFunc::Memory);
4518 else
4519 *np = alloc->in(TypeFunc::Memory);
4520 return true;
4521 }
4522
4523 Node* ClearArrayNode::make_address(Node* dest, Node* offset, bool raw_base, PhaseGVN* phase) {
4524 Node* base = dest;
4525 if (raw_base) {
4526 // May be called as part of the initialization of a just allocated object
4527 base = phase->C->top();
4528 }
4529 return phase->transform(AddPNode::make_with_base(base, dest, offset));
4530 }
4531
4532 //----------------------------clear_memory-------------------------------------
4533 // Generate code to initialize object storage to zero.
4534 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4535 Node* val,
4536 Node* raw_val,
4537 intptr_t start_offset,
4538 Node* end_offset,
4539 bool raw_base,
4540 PhaseGVN* phase) {
4541 intptr_t offset = start_offset;
4542
4543 int unit = BytesPerLong;
4544 if ((offset % unit) != 0) {
4545 Node* adr = make_address(dest, phase->MakeConX(offset), raw_base, phase);
4546 const TypePtr* atp = TypeRawPtr::BOTTOM;
4547 if (val != nullptr) {
4548 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
4549 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
4550 } else {
4551 assert(raw_val == nullptr, "val may not be null");
4552 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4553 }
4554 mem = phase->transform(mem);
4555 offset += BytesPerInt;
4556 }
4557 assert((offset % unit) == 0, "");
4558
4559 // Initialize the remaining stuff, if any, with a ClearArray.
4560 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, raw_base, phase);
4561 }
4562
4563 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4564 Node* raw_val,
4565 Node* start_offset,
4566 Node* end_offset,
4567 bool raw_base,
4568 PhaseGVN* phase) {
4569 if (start_offset == end_offset) {
4570 // nothing to do
4571 return mem;
4572 }
4573
4574 int unit = BytesPerLong;
4575 Node* zbase = start_offset;
4576 Node* zend = end_offset;
4577
4578 // Scale to the unit required by the CPU:
4579 if (!Matcher::init_array_count_is_in_bytes) {
4580 Node* shift = phase->intcon(exact_log2(unit));
4581 zbase = phase->transform(new URShiftXNode(zbase, shift) );
4582 zend = phase->transform(new URShiftXNode(zend, shift) );
4583 }
4584
4585 // Bulk clear double-words
4586 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4587 Node* adr = make_address(dest, start_offset, raw_base, phase);
4588 if (raw_val == nullptr) {
4589 raw_val = phase->MakeConX(0);
4590 }
4591 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
4592 return phase->transform(mem);
4593 }
4594
4595 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4596 Node* val,
4597 Node* raw_val,
4598 intptr_t start_offset,
4599 intptr_t end_offset,
4600 bool raw_base,
4601 PhaseGVN* phase) {
4602 if (start_offset == end_offset) {
4603 // nothing to do
4604 return mem;
4605 }
4606
4607 assert((end_offset % BytesPerInt) == 0, "odd end offset");
4608 intptr_t done_offset = end_offset;
4609 if ((done_offset % BytesPerLong) != 0) {
4610 done_offset -= BytesPerInt;
4611 }
4612 if (done_offset > start_offset) {
4613 mem = clear_memory(ctl, mem, dest, val, raw_val,
4614 start_offset, phase->MakeConX(done_offset), raw_base, phase);
4615 }
4616 if (done_offset < end_offset) { // emit the final 32-bit store
4617 Node* adr = make_address(dest, phase->MakeConX(done_offset), raw_base, phase);
4618 const TypePtr* atp = TypeRawPtr::BOTTOM;
4619 if (val != nullptr) {
4620 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
4621 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
4622 } else {
4623 assert(raw_val == nullptr, "val may not be null");
4624 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4625 }
4626 mem = phase->transform(mem);
4627 done_offset += BytesPerInt;
4628 }
4629 assert(done_offset == end_offset, "");
4630 return mem;
4631 }
4632
4633 //=============================================================================
4634 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4635 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4636 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4637 #ifdef ASSERT
4638 , _pair_idx(0)
4639 #endif
4640 {
4641 init_class_id(Class_MemBar);
4642 Node* top = C->top();
4643 init_req(TypeFunc::I_O,top);
4644 init_req(TypeFunc::FramePtr,top);
4645 init_req(TypeFunc::ReturnAdr,top);
4646 if (precedent != nullptr)
4647 init_req(TypeFunc::Parms, precedent);
4648 }
4649
4650 //------------------------------cmp--------------------------------------------
4651 uint MemBarNode::hash() const { return NO_HASH; }
4652 bool MemBarNode::cmp( const Node &n ) const {
4653 return (&n == this); // Always fail except on self
4654 }
4655
4656 //------------------------------make-------------------------------------------
4657 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4658 switch (opcode) {
4659 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
4660 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
4661 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
4662 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
4663 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
4664 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
4665 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4666 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4667 case Op_MemBarStoreLoad: return new MemBarStoreLoadNode(C, atp, pn);
4668 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
4669 case Op_MemBarFull: return new MemBarFullNode(C, atp, pn);
4670 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
4671 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
4672 case Op_Initialize: return new InitializeNode(C, atp, pn);
4673 default: ShouldNotReachHere(); return nullptr;
4674 }
4675 }
4676
4677 void MemBarNode::remove(PhaseIterGVN *igvn) {
4678 assert(outcnt() > 0 && (outcnt() <= 2 || Opcode() == Op_Initialize), "Only one or two out edges allowed");
4679 if (trailing_store() || trailing_load_store()) {
4680 MemBarNode* leading = leading_membar();
4681 if (leading != nullptr) {
4682 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4683 leading->remove(igvn);
4684 }
4685 }
4686 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4687 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4688 }
4689 if (is_Initialize()) {
4690 as_Initialize()->replace_mem_projs_by(in(TypeFunc::Memory), igvn);
4691 } else {
4692 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4693 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4694 }
4695 }
4696 }
4697
4698 //------------------------------Ideal------------------------------------------
4699 // Return a node which is more "ideal" than the current node. Strip out
4700 // control copies
4701 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4702 if (remove_dead_region(phase, can_reshape)) return this;
4703 // Don't bother trying to transform a dead node
4704 if (in(0) && in(0)->is_top()) {
4705 return nullptr;
4706 }
4707
4708 bool progress = false;
4709 // Eliminate volatile MemBars for scalar replaced objects.
4710 if (can_reshape && req() == (Precedent+1)) {
4711 bool eliminate = false;
4712 int opc = Opcode();
4713 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4714 // Volatile field loads and stores.
4715 Node* my_mem = in(MemBarNode::Precedent);
4716 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4717 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4718 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4719 // replace this Precedent (decodeN) with the Load instead.
4720 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
4721 Node* load_node = my_mem->in(1);
4722 set_req(MemBarNode::Precedent, load_node);
4723 phase->is_IterGVN()->_worklist.push(my_mem);
4724 my_mem = load_node;
4725 } else {
4726 assert(my_mem->unique_out() == this, "sanity");
4727 assert(!trailing_load_store(), "load store node can't be eliminated");
4728 del_req(Precedent);
4729 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4730 my_mem = nullptr;
4731 }
4732 progress = true;
4733 }
4734 if (my_mem != nullptr && my_mem->is_Mem()) {
4735 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4736 // Check for scalar replaced object reference.
4737 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4738 t_oop->offset() != Type::OffsetBot &&
4739 t_oop->offset() != Type::OffsetTop) {
4740 eliminate = true;
4741 }
4742 }
4743 } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4744 // Final field stores.
4745 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4746 if ((alloc != nullptr) && alloc->is_Allocate() &&
4747 alloc->as_Allocate()->does_not_escape_thread()) {
4748 // The allocated object does not escape.
4749 eliminate = true;
4750 }
4751 }
4752 if (eliminate) {
4753 // Replace MemBar projections by its inputs.
4754 PhaseIterGVN* igvn = phase->is_IterGVN();
4755 remove(igvn);
4756 // Must return either the original node (now dead) or a new node
4757 // (Do not return a top here, since that would break the uniqueness of top.)
4758 return new ConINode(TypeInt::ZERO);
4759 }
4760 }
4761 return progress ? this : nullptr;
4762 }
4763
4764 //------------------------------Value------------------------------------------
4765 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4766 if( !in(0) ) return Type::TOP;
4767 if( phase->type(in(0)) == Type::TOP )
4768 return Type::TOP;
4769 return TypeTuple::MEMBAR;
4770 }
4771
4772 //------------------------------match------------------------------------------
4773 // Construct projections for memory.
4774 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
4775 switch (proj->_con) {
4776 case TypeFunc::Control:
4777 case TypeFunc::Memory:
4778 return new MachProjNode(this, proj->_con, RegMask::EMPTY, MachProjNode::unmatched_proj);
4779 }
4780 ShouldNotReachHere();
4781 return nullptr;
4782 }
4783
4784 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4785 trailing->_kind = TrailingStore;
4786 leading->_kind = LeadingStore;
4787 #ifdef ASSERT
4788 trailing->_pair_idx = leading->_idx;
4789 leading->_pair_idx = leading->_idx;
4790 #endif
4791 }
4792
4793 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4794 trailing->_kind = TrailingLoadStore;
4795 leading->_kind = LeadingLoadStore;
4796 #ifdef ASSERT
4797 trailing->_pair_idx = leading->_idx;
4798 leading->_pair_idx = leading->_idx;
4799 #endif
4800 }
4801
4802 MemBarNode* MemBarNode::trailing_membar() const {
4803 ResourceMark rm;
4804 Node* trailing = (Node*)this;
4805 VectorSet seen;
4806 Node_Stack multis(0);
4807 do {
4808 Node* c = trailing;
4809 uint i = 0;
4810 do {
4811 trailing = nullptr;
4812 for (; i < c->outcnt(); i++) {
4813 Node* next = c->raw_out(i);
4814 if (next != c && next->is_CFG()) {
4815 if (c->is_MultiBranch()) {
4816 if (multis.node() == c) {
4817 multis.set_index(i+1);
4818 } else {
4819 multis.push(c, i+1);
4820 }
4821 }
4822 trailing = next;
4823 break;
4824 }
4825 }
4826 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4827 break;
4828 }
4829 while (multis.size() > 0) {
4830 c = multis.node();
4831 i = multis.index();
4832 if (i < c->req()) {
4833 break;
4834 }
4835 multis.pop();
4836 }
4837 } while (multis.size() > 0);
4838 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4839
4840 MemBarNode* mb = trailing->as_MemBar();
4841 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4842 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4843 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4844 return mb;
4845 }
4846
4847 MemBarNode* MemBarNode::leading_membar() const {
4848 ResourceMark rm;
4849 VectorSet seen;
4850 Node_Stack regions(0);
4851 Node* leading = in(0);
4852 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4853 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4854 leading = nullptr;
4855 while (regions.size() > 0 && leading == nullptr) {
4856 Node* r = regions.node();
4857 uint i = regions.index();
4858 if (i < r->req()) {
4859 leading = r->in(i);
4860 regions.set_index(i+1);
4861 } else {
4862 regions.pop();
4863 }
4864 }
4865 if (leading == nullptr) {
4866 assert(regions.size() == 0, "all paths should have been tried");
4867 return nullptr;
4868 }
4869 }
4870 if (leading->is_Region()) {
4871 regions.push(leading, 2);
4872 leading = leading->in(1);
4873 } else {
4874 leading = leading->in(0);
4875 }
4876 }
4877 #ifdef ASSERT
4878 Unique_Node_List wq;
4879 wq.push((Node*)this);
4880 uint found = 0;
4881 for (uint i = 0; i < wq.size(); i++) {
4882 Node* n = wq.at(i);
4883 if (n->is_Region()) {
4884 for (uint j = 1; j < n->req(); j++) {
4885 Node* in = n->in(j);
4886 if (in != nullptr && !in->is_top()) {
4887 wq.push(in);
4888 }
4889 }
4890 } else {
4891 if (n->is_MemBar() && n->as_MemBar()->leading()) {
4892 assert(n == leading, "consistency check failed");
4893 found++;
4894 } else {
4895 Node* in = n->in(0);
4896 if (in != nullptr && !in->is_top()) {
4897 wq.push(in);
4898 }
4899 }
4900 }
4901 }
4902 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4903 #endif
4904 if (leading == nullptr) {
4905 return nullptr;
4906 }
4907 MemBarNode* mb = leading->as_MemBar();
4908 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4909 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4910 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4911 return mb;
4912 }
4913
4914
4915 //===========================InitializeNode====================================
4916 // SUMMARY:
4917 // This node acts as a memory barrier on raw memory, after some raw stores.
4918 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4919 // The Initialize can 'capture' suitably constrained stores as raw inits.
4920 // It can coalesce related raw stores into larger units (called 'tiles').
4921 // It can avoid zeroing new storage for memory units which have raw inits.
4922 // At macro-expansion, it is marked 'complete', and does not optimize further.
4923 //
4924 // EXAMPLE:
4925 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4926 // ctl = incoming control; mem* = incoming memory
4927 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
4928 // First allocate uninitialized memory and fill in the header:
4929 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
4930 // ctl := alloc.Control; mem* := alloc.Memory*
4931 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
4932 // Then initialize to zero the non-header parts of the raw memory block:
4933 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4934 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4935 // After the initialize node executes, the object is ready for service:
4936 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4937 // Suppose its body is immediately initialized as {1,2}:
4938 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4939 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4940 // mem.SLICE(#short[*]) := store2
4941 //
4942 // DETAILS:
4943 // An InitializeNode collects and isolates object initialization after
4944 // an AllocateNode and before the next possible safepoint. As a
4945 // memory barrier (MemBarNode), it keeps critical stores from drifting
4946 // down past any safepoint or any publication of the allocation.
4947 // Before this barrier, a newly-allocated object may have uninitialized bits.
4948 // After this barrier, it may be treated as a real oop, and GC is allowed.
4949 //
4950 // The semantics of the InitializeNode include an implicit zeroing of
4951 // the new object from object header to the end of the object.
4952 // (The object header and end are determined by the AllocateNode.)
4953 //
4954 // Certain stores may be added as direct inputs to the InitializeNode.
4955 // These stores must update raw memory, and they must be to addresses
4956 // derived from the raw address produced by AllocateNode, and with
4957 // a constant offset. They must be ordered by increasing offset.
4958 // The first one is at in(RawStores), the last at in(req()-1).
4959 // Unlike most memory operations, they are not linked in a chain,
4960 // but are displayed in parallel as users of the rawmem output of
4961 // the allocation.
4962 //
4963 // (See comments in InitializeNode::capture_store, which continue
4964 // the example given above.)
4965 //
4966 // When the associated Allocate is macro-expanded, the InitializeNode
4967 // may be rewritten to optimize collected stores. A ClearArrayNode
4968 // may also be created at that point to represent any required zeroing.
4969 // The InitializeNode is then marked 'complete', prohibiting further
4970 // capturing of nearby memory operations.
4971 //
4972 // During macro-expansion, all captured initializations which store
4973 // constant values of 32 bits or smaller are coalesced (if advantageous)
4974 // into larger 'tiles' 32 or 64 bits. This allows an object to be
4975 // initialized in fewer memory operations. Memory words which are
4976 // covered by neither tiles nor non-constant stores are pre-zeroed
4977 // by explicit stores of zero. (The code shape happens to do all
4978 // zeroing first, then all other stores, with both sequences occurring
4979 // in order of ascending offsets.)
4980 //
4981 // Alternatively, code may be inserted between an AllocateNode and its
4982 // InitializeNode, to perform arbitrary initialization of the new object.
4983 // E.g., the object copying intrinsics insert complex data transfers here.
4984 // The initialization must then be marked as 'complete' disable the
4985 // built-in zeroing semantics and the collection of initializing stores.
4986 //
4987 // While an InitializeNode is incomplete, reads from the memory state
4988 // produced by it are optimizable if they match the control edge and
4989 // new oop address associated with the allocation/initialization.
4990 // They return a stored value (if the offset matches) or else zero.
4991 // A write to the memory state, if it matches control and address,
4992 // and if it is to a constant offset, may be 'captured' by the
4993 // InitializeNode. It is cloned as a raw memory operation and rewired
4994 // inside the initialization, to the raw oop produced by the allocation.
4995 // Operations on addresses which are provably distinct (e.g., to
4996 // other AllocateNodes) are allowed to bypass the initialization.
4997 //
4998 // The effect of all this is to consolidate object initialization
4999 // (both arrays and non-arrays, both piecewise and bulk) into a
5000 // single location, where it can be optimized as a unit.
5001 //
5002 // Only stores with an offset less than TrackedInitializationLimit words
5003 // will be considered for capture by an InitializeNode. This puts a
5004 // reasonable limit on the complexity of optimized initializations.
5005
5006 //---------------------------InitializeNode------------------------------------
5007 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
5008 : MemBarNode(C, adr_type, rawoop),
5009 _is_complete(Incomplete), _does_not_escape(false)
5010 {
5011 init_class_id(Class_Initialize);
5012
5013 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
5014 assert(in(RawAddress) == rawoop, "proper init");
5015 // Note: allocation() can be null, for secondary initialization barriers
5016 }
5017
5018 // Since this node is not matched, it will be processed by the
5019 // register allocator. Declare that there are no constraints
5020 // on the allocation of the RawAddress edge.
5021 const RegMask &InitializeNode::in_RegMask(uint idx) const {
5022 // This edge should be set to top, by the set_complete. But be conservative.
5023 if (idx == InitializeNode::RawAddress)
5024 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
5025 return RegMask::EMPTY;
5026 }
5027
5028 Node* InitializeNode::memory(uint alias_idx) {
5029 Node* mem = in(Memory);
5030 if (mem->is_MergeMem()) {
5031 return mem->as_MergeMem()->memory_at(alias_idx);
5032 } else {
5033 // incoming raw memory is not split
5034 return mem;
5035 }
5036 }
5037
5038 bool InitializeNode::is_non_zero() {
5039 if (is_complete()) return false;
5040 remove_extra_zeroes();
5041 return (req() > RawStores);
5042 }
5043
5044 void InitializeNode::set_complete(PhaseGVN* phase) {
5045 assert(!is_complete(), "caller responsibility");
5046 _is_complete = Complete;
5047
5048 // After this node is complete, it contains a bunch of
5049 // raw-memory initializations. There is no need for
5050 // it to have anything to do with non-raw memory effects.
5051 // Therefore, tell all non-raw users to re-optimize themselves,
5052 // after skipping the memory effects of this initialization.
5053 PhaseIterGVN* igvn = phase->is_IterGVN();
5054 if (igvn) igvn->add_users_to_worklist(this);
5055 }
5056
5057 // convenience function
5058 // return false if the init contains any stores already
5059 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
5060 InitializeNode* init = initialization();
5061 if (init == nullptr || init->is_complete()) {
5062 return false;
5063 }
5064 init->remove_extra_zeroes();
5065 // for now, if this allocation has already collected any inits, bail:
5066 if (init->is_non_zero()) return false;
5067 init->set_complete(phase);
5068 return true;
5069 }
5070
5071 void InitializeNode::remove_extra_zeroes() {
5072 if (req() == RawStores) return;
5073 Node* zmem = zero_memory();
5074 uint fill = RawStores;
5075 for (uint i = fill; i < req(); i++) {
5076 Node* n = in(i);
5077 if (n->is_top() || n == zmem) continue; // skip
5078 if (fill < i) set_req(fill, n); // compact
5079 ++fill;
5080 }
5081 // delete any empty spaces created:
5082 while (fill < req()) {
5083 del_req(fill);
5084 }
5085 }
5086
5087 // Helper for remembering which stores go with which offsets.
5088 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
5089 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
5090 intptr_t offset = -1;
5091 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
5092 phase, offset);
5093 if (base == nullptr) return -1; // something is dead,
5094 if (offset < 0) return -1; // dead, dead
5095 return offset;
5096 }
5097
5098 // Helper for proving that an initialization expression is
5099 // "simple enough" to be folded into an object initialization.
5100 // Attempts to prove that a store's initial value 'n' can be captured
5101 // within the initialization without creating a vicious cycle, such as:
5102 // { Foo p = new Foo(); p.next = p; }
5103 // True for constants and parameters and small combinations thereof.
5104 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
5105 ResourceMark rm;
5106 Unique_Node_List worklist;
5107 worklist.push(value);
5108
5109 uint complexity_limit = 20;
5110 for (uint j = 0; j < worklist.size(); j++) {
5111 if (j >= complexity_limit) {
5112 return false; // Bail out if processed too many nodes
5113 }
5114
5115 Node* n = worklist.at(j);
5116 if (n == nullptr) continue; // (can this really happen?)
5117 if (n->is_Proj()) n = n->in(0);
5118 if (n == this) return false; // found a cycle
5119 if (n->is_Con()) continue;
5120 if (n->is_Start()) continue; // params, etc., are OK
5121 if (n->is_Root()) continue; // even better
5122
5123 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
5124 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
5125 continue;
5126 }
5127
5128 Node* ctl = n->in(0);
5129 if (ctl != nullptr && !ctl->is_top()) {
5130 if (ctl->is_Proj()) ctl = ctl->in(0);
5131 if (ctl == this) return false;
5132
5133 // If we already know that the enclosing memory op is pinned right after
5134 // the init, then any control flow that the store has picked up
5135 // must have preceded the init, or else be equal to the init.
5136 // Even after loop optimizations (which might change control edges)
5137 // a store is never pinned *before* the availability of its inputs.
5138 if (!MemNode::all_controls_dominate(n, this, phase)) {
5139 return false; // failed to prove a good control
5140 }
5141 }
5142
5143 // Check data edges for possible dependencies on 'this'.
5144 for (uint i = 1; i < n->req(); i++) {
5145 Node* m = n->in(i);
5146 if (m == nullptr || m == n || m->is_top()) continue;
5147
5148 // Only process data inputs once
5149 worklist.push(m);
5150 }
5151 }
5152
5153 return true;
5154 }
5155
5156 // Here are all the checks a Store must pass before it can be moved into
5157 // an initialization. Returns zero if a check fails.
5158 // On success, returns the (constant) offset to which the store applies,
5159 // within the initialized memory.
5160 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
5161 const int FAIL = 0;
5162 if (st->req() != MemNode::ValueIn + 1)
5163 return FAIL; // an inscrutable StoreNode (card mark?)
5164 Node* ctl = st->in(MemNode::Control);
5165 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
5166 return FAIL; // must be unconditional after the initialization
5167 Node* mem = st->in(MemNode::Memory);
5168 if (!(mem->is_Proj() && mem->in(0) == this))
5169 return FAIL; // must not be preceded by other stores
5170 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
5171 if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) &&
5172 !bs->can_initialize_object(st)) {
5173 return FAIL;
5174 }
5175 Node* adr = st->in(MemNode::Address);
5176 intptr_t offset;
5177 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
5178 if (alloc == nullptr)
5179 return FAIL; // inscrutable address
5180 if (alloc != allocation())
5181 return FAIL; // wrong allocation! (store needs to float up)
5182 int size_in_bytes = st->memory_size();
5183 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
5184 return FAIL; // mismatched access
5185 }
5186 Node* val = st->in(MemNode::ValueIn);
5187
5188 if (!detect_init_independence(val, phase))
5189 return FAIL; // stored value must be 'simple enough'
5190
5191 // The Store can be captured only if nothing after the allocation
5192 // and before the Store is using the memory location that the store
5193 // overwrites.
5194 bool failed = false;
5195 // If is_complete_with_arraycopy() is true the shape of the graph is
5196 // well defined and is safe so no need for extra checks.
5197 if (!is_complete_with_arraycopy()) {
5198 // We are going to look at each use of the memory state following
5199 // the allocation to make sure nothing reads the memory that the
5200 // Store writes.
5201 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
5202 int alias_idx = phase->C->get_alias_index(t_adr);
5203 ResourceMark rm;
5204 Unique_Node_List mems;
5205 mems.push(mem);
5206 Node* unique_merge = nullptr;
5207 for (uint next = 0; next < mems.size(); ++next) {
5208 Node *m = mems.at(next);
5209 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
5210 Node *n = m->fast_out(j);
5211 if (n->outcnt() == 0) {
5212 continue;
5213 }
5214 if (n == st) {
5215 continue;
5216 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
5217 // If the control of this use is different from the control
5218 // of the Store which is right after the InitializeNode then
5219 // this node cannot be between the InitializeNode and the
5220 // Store.
5221 continue;
5222 } else if (n->is_MergeMem()) {
5223 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
5224 // We can hit a MergeMemNode (that will likely go away
5225 // later) that is a direct use of the memory state
5226 // following the InitializeNode on the same slice as the
5227 // store node that we'd like to capture. We need to check
5228 // the uses of the MergeMemNode.
5229 mems.push(n);
5230 }
5231 } else if (n->is_Mem()) {
5232 Node* other_adr = n->in(MemNode::Address);
5233 if (other_adr == adr) {
5234 failed = true;
5235 break;
5236 } else {
5237 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
5238 if (other_t_adr != nullptr) {
5239 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
5240 if (other_alias_idx == alias_idx) {
5241 // A load from the same memory slice as the store right
5242 // after the InitializeNode. We check the control of the
5243 // object/array that is loaded from. If it's the same as
5244 // the store control then we cannot capture the store.
5245 assert(!n->is_Store(), "2 stores to same slice on same control?");
5246 Node* base = other_adr;
5247 if (base->is_Phi()) {
5248 // In rare case, base may be a PhiNode and it may read
5249 // the same memory slice between InitializeNode and store.
5250 failed = true;
5251 break;
5252 }
5253 assert(base->is_AddP(), "should be addp but is %s", base->Name());
5254 base = base->in(AddPNode::Base);
5255 if (base != nullptr) {
5256 base = base->uncast();
5257 if (base->is_Proj() && base->in(0) == alloc) {
5258 failed = true;
5259 break;
5260 }
5261 }
5262 }
5263 }
5264 }
5265 } else {
5266 failed = true;
5267 break;
5268 }
5269 }
5270 }
5271 }
5272 if (failed) {
5273 if (!can_reshape) {
5274 // We decided we couldn't capture the store during parsing. We
5275 // should try again during the next IGVN once the graph is
5276 // cleaner.
5277 phase->C->record_for_igvn(st);
5278 }
5279 return FAIL;
5280 }
5281
5282 return offset; // success
5283 }
5284
5285 // Find the captured store in(i) which corresponds to the range
5286 // [start..start+size) in the initialized object.
5287 // If there is one, return its index i. If there isn't, return the
5288 // negative of the index where it should be inserted.
5289 // Return 0 if the queried range overlaps an initialization boundary
5290 // or if dead code is encountered.
5291 // If size_in_bytes is zero, do not bother with overlap checks.
5292 int InitializeNode::captured_store_insertion_point(intptr_t start,
5293 int size_in_bytes,
5294 PhaseValues* phase) {
5295 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
5296
5297 if (is_complete())
5298 return FAIL; // arraycopy got here first; punt
5299
5300 assert(allocation() != nullptr, "must be present");
5301
5302 // no negatives, no header fields:
5303 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
5304
5305 // after a certain size, we bail out on tracking all the stores:
5306 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5307 if (start >= ti_limit) return FAIL;
5308
5309 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
5310 if (i >= limit) return -(int)i; // not found; here is where to put it
5311
5312 Node* st = in(i);
5313 intptr_t st_off = get_store_offset(st, phase);
5314 if (st_off < 0) {
5315 if (st != zero_memory()) {
5316 return FAIL; // bail out if there is dead garbage
5317 }
5318 } else if (st_off > start) {
5319 // ...we are done, since stores are ordered
5320 if (st_off < start + size_in_bytes) {
5321 return FAIL; // the next store overlaps
5322 }
5323 return -(int)i; // not found; here is where to put it
5324 } else if (st_off < start) {
5325 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
5326 if (size_in_bytes != 0 &&
5327 start < st_off + MAX_STORE &&
5328 start < st_off + st->as_Store()->memory_size()) {
5329 return FAIL; // the previous store overlaps
5330 }
5331 } else {
5332 if (size_in_bytes != 0 &&
5333 st->as_Store()->memory_size() != size_in_bytes) {
5334 return FAIL; // mismatched store size
5335 }
5336 return i;
5337 }
5338
5339 ++i;
5340 }
5341 }
5342
5343 // Look for a captured store which initializes at the offset 'start'
5344 // with the given size. If there is no such store, and no other
5345 // initialization interferes, then return zero_memory (the memory
5346 // projection of the AllocateNode).
5347 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
5348 PhaseValues* phase) {
5349 assert(stores_are_sane(phase), "");
5350 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5351 if (i == 0) {
5352 return nullptr; // something is dead
5353 } else if (i < 0) {
5354 return zero_memory(); // just primordial zero bits here
5355 } else {
5356 Node* st = in(i); // here is the store at this position
5357 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
5358 return st;
5359 }
5360 }
5361
5362 // Create, as a raw pointer, an address within my new object at 'offset'.
5363 Node* InitializeNode::make_raw_address(intptr_t offset,
5364 PhaseGVN* phase) {
5365 Node* addr = in(RawAddress);
5366 if (offset != 0) {
5367 Compile* C = phase->C;
5368 addr = phase->transform(AddPNode::make_off_heap(addr, phase->MakeConX(offset)));
5369 }
5370 return addr;
5371 }
5372
5373 // Clone the given store, converting it into a raw store
5374 // initializing a field or element of my new object.
5375 // Caller is responsible for retiring the original store,
5376 // with subsume_node or the like.
5377 //
5378 // From the example above InitializeNode::InitializeNode,
5379 // here are the old stores to be captured:
5380 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
5381 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
5382 //
5383 // Here is the changed code; note the extra edges on init:
5384 // alloc = (Allocate ...)
5385 // rawoop = alloc.RawAddress
5386 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
5387 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
5388 // init = (Initialize alloc.Control alloc.Memory rawoop
5389 // rawstore1 rawstore2)
5390 //
5391 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
5392 PhaseGVN* phase, bool can_reshape) {
5393 assert(stores_are_sane(phase), "");
5394
5395 if (start < 0) return nullptr;
5396 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
5397
5398 Compile* C = phase->C;
5399 int size_in_bytes = st->memory_size();
5400 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5401 if (i == 0) return nullptr; // bail out
5402 Node* prev_mem = nullptr; // raw memory for the captured store
5403 if (i > 0) {
5404 prev_mem = in(i); // there is a pre-existing store under this one
5405 set_req(i, C->top()); // temporarily disconnect it
5406 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
5407 } else {
5408 i = -i; // no pre-existing store
5409 prev_mem = zero_memory(); // a slice of the newly allocated object
5410 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
5411 set_req(--i, C->top()); // reuse this edge; it has been folded away
5412 else
5413 ins_req(i, C->top()); // build a new edge
5414 }
5415 Node* new_st = st->clone_with_adr_type(TypeRawPtr::BOTTOM);
5416 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
5417 new_st->set_req(MemNode::Control, in(Control));
5418 new_st->set_req(MemNode::Memory, prev_mem);
5419 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
5420 bs->eliminate_gc_barrier_data(new_st);
5421 new_st = phase->transform(new_st);
5422
5423 // At this point, new_st might have swallowed a pre-existing store
5424 // at the same offset, or perhaps new_st might have disappeared,
5425 // if it redundantly stored the same value (or zero to fresh memory).
5426
5427 // In any case, wire it in:
5428 PhaseIterGVN* igvn = phase->is_IterGVN();
5429 if (igvn) {
5430 igvn->rehash_node_delayed(this);
5431 }
5432 set_req(i, new_st);
5433
5434 // The caller may now kill the old guy.
5435 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
5436 assert(check_st == new_st || check_st == nullptr, "must be findable");
5437 assert(!is_complete(), "");
5438 return new_st;
5439 }
5440
5441 static bool store_constant(jlong* tiles, int num_tiles,
5442 intptr_t st_off, int st_size,
5443 jlong con) {
5444 if ((st_off & (st_size-1)) != 0)
5445 return false; // strange store offset (assume size==2**N)
5446 address addr = (address)tiles + st_off;
5447 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
5448 switch (st_size) {
5449 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
5450 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
5451 case sizeof(jint): *(jint*) addr = (jint) con; break;
5452 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
5453 default: return false; // strange store size (detect size!=2**N here)
5454 }
5455 return true; // return success to caller
5456 }
5457
5458 // Coalesce subword constants into int constants and possibly
5459 // into long constants. The goal, if the CPU permits,
5460 // is to initialize the object with a small number of 64-bit tiles.
5461 // Also, convert floating-point constants to bit patterns.
5462 // Non-constants are not relevant to this pass.
5463 //
5464 // In terms of the running example on InitializeNode::InitializeNode
5465 // and InitializeNode::capture_store, here is the transformation
5466 // of rawstore1 and rawstore2 into rawstore12:
5467 // alloc = (Allocate ...)
5468 // rawoop = alloc.RawAddress
5469 // tile12 = 0x00010002
5470 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
5471 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
5472 //
5473 void
5474 InitializeNode::coalesce_subword_stores(intptr_t header_size,
5475 Node* size_in_bytes,
5476 PhaseGVN* phase) {
5477 Compile* C = phase->C;
5478
5479 assert(stores_are_sane(phase), "");
5480 // Note: After this pass, they are not completely sane,
5481 // since there may be some overlaps.
5482
5483 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
5484
5485 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5486 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
5487 size_limit = MIN2(size_limit, ti_limit);
5488 size_limit = align_up(size_limit, BytesPerLong);
5489 int num_tiles = size_limit / BytesPerLong;
5490
5491 // allocate space for the tile map:
5492 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
5493 jlong tiles_buf[small_len];
5494 Node* nodes_buf[small_len];
5495 jlong inits_buf[small_len];
5496 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
5497 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5498 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
5499 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
5500 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
5501 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5502 // tiles: exact bitwise model of all primitive constants
5503 // nodes: last constant-storing node subsumed into the tiles model
5504 // inits: which bytes (in each tile) are touched by any initializations
5505
5506 //// Pass A: Fill in the tile model with any relevant stores.
5507
5508 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
5509 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
5510 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
5511 Node* zmem = zero_memory(); // initially zero memory state
5512 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5513 Node* st = in(i);
5514 intptr_t st_off = get_store_offset(st, phase);
5515
5516 // Figure out the store's offset and constant value:
5517 if (st_off < header_size) continue; //skip (ignore header)
5518 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
5519 int st_size = st->as_Store()->memory_size();
5520 if (st_off + st_size > size_limit) break;
5521
5522 // Record which bytes are touched, whether by constant or not.
5523 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
5524 continue; // skip (strange store size)
5525
5526 const Type* val = phase->type(st->in(MemNode::ValueIn));
5527 if (!val->singleton()) continue; //skip (non-con store)
5528 BasicType type = val->basic_type();
5529
5530 jlong con = 0;
5531 switch (type) {
5532 case T_INT: con = val->is_int()->get_con(); break;
5533 case T_LONG: con = val->is_long()->get_con(); break;
5534 case T_FLOAT: con = jint_cast(val->getf()); break;
5535 case T_DOUBLE: con = jlong_cast(val->getd()); break;
5536 default: continue; //skip (odd store type)
5537 }
5538
5539 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
5540 st->Opcode() == Op_StoreL) {
5541 continue; // This StoreL is already optimal.
5542 }
5543
5544 // Store down the constant.
5545 store_constant(tiles, num_tiles, st_off, st_size, con);
5546
5547 intptr_t j = st_off >> LogBytesPerLong;
5548
5549 if (type == T_INT && st_size == BytesPerInt
5550 && (st_off & BytesPerInt) == BytesPerInt) {
5551 jlong lcon = tiles[j];
5552 if (!Matcher::isSimpleConstant64(lcon) &&
5553 st->Opcode() == Op_StoreI) {
5554 // This StoreI is already optimal by itself.
5555 jint* intcon = (jint*) &tiles[j];
5556 intcon[1] = 0; // undo the store_constant()
5557
5558 // If the previous store is also optimal by itself, back up and
5559 // undo the action of the previous loop iteration... if we can.
5560 // But if we can't, just let the previous half take care of itself.
5561 st = nodes[j];
5562 st_off -= BytesPerInt;
5563 con = intcon[0];
5564 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
5565 assert(st_off >= header_size, "still ignoring header");
5566 assert(get_store_offset(st, phase) == st_off, "must be");
5567 assert(in(i-1) == zmem, "must be");
5568 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
5569 assert(con == tcon->is_int()->get_con(), "must be");
5570 // Undo the effects of the previous loop trip, which swallowed st:
5571 intcon[0] = 0; // undo store_constant()
5572 set_req(i-1, st); // undo set_req(i, zmem)
5573 nodes[j] = nullptr; // undo nodes[j] = st
5574 --old_subword; // undo ++old_subword
5575 }
5576 continue; // This StoreI is already optimal.
5577 }
5578 }
5579
5580 // This store is not needed.
5581 set_req(i, zmem);
5582 nodes[j] = st; // record for the moment
5583 if (st_size < BytesPerLong) // something has changed
5584 ++old_subword; // includes int/float, but who's counting...
5585 else ++old_long;
5586 }
5587
5588 if ((old_subword + old_long) == 0)
5589 return; // nothing more to do
5590
5591 //// Pass B: Convert any non-zero tiles into optimal constant stores.
5592 // Be sure to insert them before overlapping non-constant stores.
5593 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
5594 for (int j = 0; j < num_tiles; j++) {
5595 jlong con = tiles[j];
5596 jlong init = inits[j];
5597 if (con == 0) continue;
5598 jint con0, con1; // split the constant, address-wise
5599 jint init0, init1; // split the init map, address-wise
5600 { union { jlong con; jint intcon[2]; } u;
5601 u.con = con;
5602 con0 = u.intcon[0];
5603 con1 = u.intcon[1];
5604 u.con = init;
5605 init0 = u.intcon[0];
5606 init1 = u.intcon[1];
5607 }
5608
5609 Node* old = nodes[j];
5610 assert(old != nullptr, "need the prior store");
5611 intptr_t offset = (j * BytesPerLong);
5612
5613 bool split = !Matcher::isSimpleConstant64(con);
5614
5615 if (offset < header_size) {
5616 assert(offset + BytesPerInt >= header_size, "second int counts");
5617 assert(*(jint*)&tiles[j] == 0, "junk in header");
5618 split = true; // only the second word counts
5619 // Example: int a[] = { 42 ... }
5620 } else if (con0 == 0 && init0 == -1) {
5621 split = true; // first word is covered by full inits
5622 // Example: int a[] = { ... foo(), 42 ... }
5623 } else if (con1 == 0 && init1 == -1) {
5624 split = true; // second word is covered by full inits
5625 // Example: int a[] = { ... 42, foo() ... }
5626 }
5627
5628 // Here's a case where init0 is neither 0 nor -1:
5629 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
5630 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5631 // In this case the tile is not split; it is (jlong)42.
5632 // The big tile is stored down, and then the foo() value is inserted.
5633 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5634
5635 Node* ctl = old->in(MemNode::Control);
5636 Node* adr = make_raw_address(offset, phase);
5637 const TypePtr* atp = TypeRawPtr::BOTTOM;
5638
5639 // One or two coalesced stores to plop down.
5640 Node* st[2];
5641 intptr_t off[2];
5642 int nst = 0;
5643 if (!split) {
5644 ++new_long;
5645 off[nst] = offset;
5646 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5647 phase->longcon(con), T_LONG, MemNode::unordered);
5648 } else {
5649 // Omit either if it is a zero.
5650 if (con0 != 0) {
5651 ++new_int;
5652 off[nst] = offset;
5653 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5654 phase->intcon(con0), T_INT, MemNode::unordered);
5655 }
5656 if (con1 != 0) {
5657 ++new_int;
5658 offset += BytesPerInt;
5659 adr = make_raw_address(offset, phase);
5660 off[nst] = offset;
5661 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5662 phase->intcon(con1), T_INT, MemNode::unordered);
5663 }
5664 }
5665
5666 // Insert second store first, then the first before the second.
5667 // Insert each one just before any overlapping non-constant stores.
5668 while (nst > 0) {
5669 Node* st1 = st[--nst];
5670 C->copy_node_notes_to(st1, old);
5671 st1 = phase->transform(st1);
5672 offset = off[nst];
5673 assert(offset >= header_size, "do not smash header");
5674 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5675 guarantee(ins_idx != 0, "must re-insert constant store");
5676 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
5677 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5678 set_req(--ins_idx, st1);
5679 else
5680 ins_req(ins_idx, st1);
5681 }
5682 }
5683
5684 if (PrintCompilation && WizardMode)
5685 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5686 old_subword, old_long, new_int, new_long);
5687 if (C->log() != nullptr)
5688 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5689 old_subword, old_long, new_int, new_long);
5690
5691 // Clean up any remaining occurrences of zmem:
5692 remove_extra_zeroes();
5693 }
5694
5695 // Explore forward from in(start) to find the first fully initialized
5696 // word, and return its offset. Skip groups of subword stores which
5697 // together initialize full words. If in(start) is itself part of a
5698 // fully initialized word, return the offset of in(start). If there
5699 // are no following full-word stores, or if something is fishy, return
5700 // a negative value.
5701 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5702 int int_map = 0;
5703 intptr_t int_map_off = 0;
5704 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
5705
5706 for (uint i = start, limit = req(); i < limit; i++) {
5707 Node* st = in(i);
5708
5709 intptr_t st_off = get_store_offset(st, phase);
5710 if (st_off < 0) break; // return conservative answer
5711
5712 int st_size = st->as_Store()->memory_size();
5713 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5714 return st_off; // we found a complete word init
5715 }
5716
5717 // update the map:
5718
5719 intptr_t this_int_off = align_down(st_off, BytesPerInt);
5720 if (this_int_off != int_map_off) {
5721 // reset the map:
5722 int_map = 0;
5723 int_map_off = this_int_off;
5724 }
5725
5726 int subword_off = st_off - this_int_off;
5727 int_map |= right_n_bits(st_size) << subword_off;
5728 if ((int_map & FULL_MAP) == FULL_MAP) {
5729 return this_int_off; // we found a complete word init
5730 }
5731
5732 // Did this store hit or cross the word boundary?
5733 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5734 if (next_int_off == this_int_off + BytesPerInt) {
5735 // We passed the current int, without fully initializing it.
5736 int_map_off = next_int_off;
5737 int_map >>= BytesPerInt;
5738 } else if (next_int_off > this_int_off + BytesPerInt) {
5739 // We passed the current and next int.
5740 return this_int_off + BytesPerInt;
5741 }
5742 }
5743
5744 return -1;
5745 }
5746
5747
5748 // Called when the associated AllocateNode is expanded into CFG.
5749 // At this point, we may perform additional optimizations.
5750 // Linearize the stores by ascending offset, to make memory
5751 // activity as coherent as possible.
5752 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5753 intptr_t header_size,
5754 Node* size_in_bytes,
5755 PhaseIterGVN* phase) {
5756 assert(!is_complete(), "not already complete");
5757 assert(stores_are_sane(phase), "");
5758 assert(allocation() != nullptr, "must be present");
5759
5760 remove_extra_zeroes();
5761
5762 if (ReduceFieldZeroing || ReduceBulkZeroing)
5763 // reduce instruction count for common initialization patterns
5764 coalesce_subword_stores(header_size, size_in_bytes, phase);
5765
5766 Node* zmem = zero_memory(); // initially zero memory state
5767 Node* inits = zmem; // accumulating a linearized chain of inits
5768 #ifdef ASSERT
5769 intptr_t first_offset = allocation()->minimum_header_size();
5770 intptr_t last_init_off = first_offset; // previous init offset
5771 intptr_t last_init_end = first_offset; // previous init offset+size
5772 intptr_t last_tile_end = first_offset; // previous tile offset+size
5773 #endif
5774 intptr_t zeroes_done = header_size;
5775
5776 bool do_zeroing = true; // we might give up if inits are very sparse
5777 int big_init_gaps = 0; // how many large gaps have we seen?
5778
5779 if (UseTLAB && ZeroTLAB) do_zeroing = false;
5780 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
5781
5782 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5783 Node* st = in(i);
5784 intptr_t st_off = get_store_offset(st, phase);
5785 if (st_off < 0)
5786 break; // unknown junk in the inits
5787 if (st->in(MemNode::Memory) != zmem)
5788 break; // complicated store chains somehow in list
5789
5790 int st_size = st->as_Store()->memory_size();
5791 intptr_t next_init_off = st_off + st_size;
5792
5793 if (do_zeroing && zeroes_done < next_init_off) {
5794 // See if this store needs a zero before it or under it.
5795 intptr_t zeroes_needed = st_off;
5796
5797 if (st_size < BytesPerInt) {
5798 // Look for subword stores which only partially initialize words.
5799 // If we find some, we must lay down some word-level zeroes first,
5800 // underneath the subword stores.
5801 //
5802 // Examples:
5803 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
5804 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
5805 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
5806 //
5807 // Note: coalesce_subword_stores may have already done this,
5808 // if it was prompted by constant non-zero subword initializers.
5809 // But this case can still arise with non-constant stores.
5810
5811 intptr_t next_full_store = find_next_fullword_store(i, phase);
5812
5813 // In the examples above:
5814 // in(i) p q r s x y z
5815 // st_off 12 13 14 15 12 13 14
5816 // st_size 1 1 1 1 1 1 1
5817 // next_full_s. 12 16 16 16 16 16 16
5818 // z's_done 12 16 16 16 12 16 12
5819 // z's_needed 12 16 16 16 16 16 16
5820 // zsize 0 0 0 0 4 0 4
5821 if (next_full_store < 0) {
5822 // Conservative tack: Zero to end of current word.
5823 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5824 } else {
5825 // Zero to beginning of next fully initialized word.
5826 // Or, don't zero at all, if we are already in that word.
5827 assert(next_full_store >= zeroes_needed, "must go forward");
5828 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5829 zeroes_needed = next_full_store;
5830 }
5831 }
5832
5833 if (zeroes_needed > zeroes_done) {
5834 intptr_t zsize = zeroes_needed - zeroes_done;
5835 // Do some incremental zeroing on rawmem, in parallel with inits.
5836 zeroes_done = align_down(zeroes_done, BytesPerInt);
5837 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5838 allocation()->in(AllocateNode::InitValue),
5839 allocation()->in(AllocateNode::RawInitValue),
5840 zeroes_done, zeroes_needed,
5841 true,
5842 phase);
5843 zeroes_done = zeroes_needed;
5844 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5845 do_zeroing = false; // leave the hole, next time
5846 }
5847 }
5848
5849 // Collect the store and move on:
5850 phase->replace_input_of(st, MemNode::Memory, inits);
5851 inits = st; // put it on the linearized chain
5852 set_req(i, zmem); // unhook from previous position
5853
5854 if (zeroes_done == st_off)
5855 zeroes_done = next_init_off;
5856
5857 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5858
5859 #ifdef ASSERT
5860 // Various order invariants. Weaker than stores_are_sane because
5861 // a large constant tile can be filled in by smaller non-constant stores.
5862 assert(st_off >= last_init_off, "inits do not reverse");
5863 last_init_off = st_off;
5864 const Type* val = nullptr;
5865 if (st_size >= BytesPerInt &&
5866 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5867 (int)val->basic_type() < (int)T_OBJECT) {
5868 assert(st_off >= last_tile_end, "tiles do not overlap");
5869 assert(st_off >= last_init_end, "tiles do not overwrite inits");
5870 last_tile_end = MAX2(last_tile_end, next_init_off);
5871 } else {
5872 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5873 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5874 assert(st_off >= last_init_end, "inits do not overlap");
5875 last_init_end = next_init_off; // it's a non-tile
5876 }
5877 #endif //ASSERT
5878 }
5879
5880 remove_extra_zeroes(); // clear out all the zmems left over
5881 add_req(inits);
5882
5883 if (!(UseTLAB && ZeroTLAB)) {
5884 // If anything remains to be zeroed, zero it all now.
5885 zeroes_done = align_down(zeroes_done, BytesPerInt);
5886 // if it is the last unused 4 bytes of an instance, forget about it
5887 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5888 if (zeroes_done + BytesPerLong >= size_limit) {
5889 AllocateNode* alloc = allocation();
5890 assert(alloc != nullptr, "must be present");
5891 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5892 Node* klass_node = alloc->in(AllocateNode::KlassNode);
5893 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5894 if (zeroes_done == k->layout_helper())
5895 zeroes_done = size_limit;
5896 }
5897 }
5898 if (zeroes_done < size_limit) {
5899 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5900 allocation()->in(AllocateNode::InitValue),
5901 allocation()->in(AllocateNode::RawInitValue),
5902 zeroes_done, size_in_bytes, true, phase);
5903 }
5904 }
5905
5906 set_complete(phase);
5907 return rawmem;
5908 }
5909
5910 void InitializeNode::replace_mem_projs_by(Node* mem, Compile* C) {
5911 auto replace_proj = [&](ProjNode* proj) {
5912 C->gvn_replace_by(proj, mem);
5913 return CONTINUE;
5914 };
5915 apply_to_projs(replace_proj, TypeFunc::Memory);
5916 }
5917
5918 void InitializeNode::replace_mem_projs_by(Node* mem, PhaseIterGVN* igvn) {
5919 DUIterator_Fast imax, i = fast_outs(imax);
5920 auto replace_proj = [&](ProjNode* proj) {
5921 igvn->replace_node(proj, mem);
5922 --i; --imax;
5923 return CONTINUE;
5924 };
5925 apply_to_projs(imax, i, replace_proj, TypeFunc::Memory);
5926 }
5927
5928 bool InitializeNode::already_has_narrow_mem_proj_with_adr_type(const TypePtr* adr_type) const {
5929 auto find_proj = [&](ProjNode* proj) {
5930 if (proj->adr_type() == adr_type) {
5931 return BREAK_AND_RETURN_CURRENT_PROJ;
5932 }
5933 return CONTINUE;
5934 };
5935 DUIterator_Fast imax, i = fast_outs(imax);
5936 return apply_to_narrow_mem_projs_any_iterator(UsesIteratorFast(imax, i, this), find_proj) != nullptr;
5937 }
5938
5939 MachProjNode* InitializeNode::mem_mach_proj() const {
5940 auto find_proj = [](ProjNode* proj) {
5941 if (proj->is_MachProj()) {
5942 return BREAK_AND_RETURN_CURRENT_PROJ;
5943 }
5944 return CONTINUE;
5945 };
5946 ProjNode* proj = apply_to_projs(find_proj, TypeFunc::Memory);
5947 if (proj == nullptr) {
5948 return nullptr;
5949 }
5950 return proj->as_MachProj();
5951 }
5952
5953 #ifdef ASSERT
5954 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5955 if (is_complete())
5956 return true; // stores could be anything at this point
5957 assert(allocation() != nullptr, "must be present");
5958 intptr_t last_off = allocation()->minimum_header_size();
5959 for (uint i = InitializeNode::RawStores; i < req(); i++) {
5960 Node* st = in(i);
5961 intptr_t st_off = get_store_offset(st, phase);
5962 if (st_off < 0) continue; // ignore dead garbage
5963 if (last_off > st_off) {
5964 tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off);
5965 this->dump(2);
5966 assert(false, "ascending store offsets");
5967 return false;
5968 }
5969 last_off = st_off + st->as_Store()->memory_size();
5970 }
5971 return true;
5972 }
5973 #endif //ASSERT
5974
5975
5976
5977
5978 //============================MergeMemNode=====================================
5979 //
5980 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
5981 // contributing store or call operations. Each contributor provides the memory
5982 // state for a particular "alias type" (see Compile::alias_type). For example,
5983 // if a MergeMem has an input X for alias category #6, then any memory reference
5984 // to alias category #6 may use X as its memory state input, as an exact equivalent
5985 // to using the MergeMem as a whole.
5986 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5987 //
5988 // (Here, the <N> notation gives the index of the relevant adr_type.)
5989 //
5990 // In one special case (and more cases in the future), alias categories overlap.
5991 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5992 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
5993 // it is exactly equivalent to that state W:
5994 // MergeMem(<Bot>: W) <==> W
5995 //
5996 // Usually, the merge has more than one input. In that case, where inputs
5997 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5998 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5999 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
6000 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
6001 //
6002 // A merge can take a "wide" memory state as one of its narrow inputs.
6003 // This simply means that the merge observes out only the relevant parts of
6004 // the wide input. That is, wide memory states arriving at narrow merge inputs
6005 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
6006 //
6007 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
6008 // and that memory slices "leak through":
6009 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
6010 //
6011 // But, in such a cascade, repeated memory slices can "block the leak":
6012 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
6013 //
6014 // In the last example, Y is not part of the combined memory state of the
6015 // outermost MergeMem. The system must, of course, prevent unschedulable
6016 // memory states from arising, so you can be sure that the state Y is somehow
6017 // a precursor to state Y'.
6018 //
6019 //
6020 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
6021 // of each MergeMemNode array are exactly the numerical alias indexes, including
6022 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
6023 // Compile::alias_type (and kin) produce and manage these indexes.
6024 //
6025 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
6026 // (Note that this provides quick access to the top node inside MergeMem methods,
6027 // without the need to reach out via TLS to Compile::current.)
6028 //
6029 // As a consequence of what was just described, a MergeMem that represents a full
6030 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
6031 // containing all alias categories.
6032 //
6033 // MergeMem nodes never (?) have control inputs, so in(0) is null.
6034 //
6035 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
6036 // a memory state for the alias type <N>, or else the top node, meaning that
6037 // there is no particular input for that alias type. Note that the length of
6038 // a MergeMem is variable, and may be extended at any time to accommodate new
6039 // memory states at larger alias indexes. When merges grow, they are of course
6040 // filled with "top" in the unused in() positions.
6041 //
6042 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
6043 // (Top was chosen because it works smoothly with passes like GCM.)
6044 //
6045 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
6046 // the type of random VM bits like TLS references.) Since it is always the
6047 // first non-Bot memory slice, some low-level loops use it to initialize an
6048 // index variable: for (i = AliasIdxRaw; i < req(); i++).
6049 //
6050 //
6051 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
6052 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
6053 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
6054 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
6055 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
6056 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
6057 //
6058 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
6059 // really that different from the other memory inputs. An abbreviation called
6060 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
6061 //
6062 //
6063 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
6064 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
6065 // that "emerges though" the base memory will be marked as excluding the alias types
6066 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
6067 //
6068 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
6069 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
6070 //
6071 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
6072 // (It is currently unimplemented.) As you can see, the resulting merge is
6073 // actually a disjoint union of memory states, rather than an overlay.
6074 //
6075
6076 //------------------------------MergeMemNode-----------------------------------
6077 Node* MergeMemNode::make_empty_memory() {
6078 Node* empty_memory = (Node*) Compile::current()->top();
6079 assert(empty_memory->is_top(), "correct sentinel identity");
6080 return empty_memory;
6081 }
6082
6083 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
6084 init_class_id(Class_MergeMem);
6085 // all inputs are nullified in Node::Node(int)
6086 // set_input(0, nullptr); // no control input
6087
6088 // Initialize the edges uniformly to top, for starters.
6089 Node* empty_mem = make_empty_memory();
6090 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
6091 init_req(i,empty_mem);
6092 }
6093 assert(empty_memory() == empty_mem, "");
6094
6095 if( new_base != nullptr && new_base->is_MergeMem() ) {
6096 MergeMemNode* mdef = new_base->as_MergeMem();
6097 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
6098 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
6099 mms.set_memory(mms.memory2());
6100 }
6101 assert(base_memory() == mdef->base_memory(), "");
6102 } else {
6103 set_base_memory(new_base);
6104 }
6105 }
6106
6107 // Make a new, untransformed MergeMem with the same base as 'mem'.
6108 // If mem is itself a MergeMem, populate the result with the same edges.
6109 MergeMemNode* MergeMemNode::make(Node* mem) {
6110 return new MergeMemNode(mem);
6111 }
6112
6113 //------------------------------cmp--------------------------------------------
6114 uint MergeMemNode::hash() const { return NO_HASH; }
6115 bool MergeMemNode::cmp( const Node &n ) const {
6116 return (&n == this); // Always fail except on self
6117 }
6118
6119 //------------------------------Identity---------------------------------------
6120 Node* MergeMemNode::Identity(PhaseGVN* phase) {
6121 // Identity if this merge point does not record any interesting memory
6122 // disambiguations.
6123 Node* base_mem = base_memory();
6124 Node* empty_mem = empty_memory();
6125 if (base_mem != empty_mem) { // Memory path is not dead?
6126 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6127 Node* mem = in(i);
6128 if (mem != empty_mem && mem != base_mem) {
6129 return this; // Many memory splits; no change
6130 }
6131 }
6132 }
6133 return base_mem; // No memory splits; ID on the one true input
6134 }
6135
6136 //------------------------------Ideal------------------------------------------
6137 // This method is invoked recursively on chains of MergeMem nodes
6138 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
6139 // Remove chain'd MergeMems
6140 //
6141 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
6142 // relative to the "in(Bot)". Since we are patching both at the same time,
6143 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
6144 // but rewrite each "in(i)" relative to the new "in(Bot)".
6145 Node *progress = nullptr;
6146
6147
6148 Node* old_base = base_memory();
6149 Node* empty_mem = empty_memory();
6150 if (old_base == empty_mem)
6151 return nullptr; // Dead memory path.
6152
6153 MergeMemNode* old_mbase;
6154 if (old_base != nullptr && old_base->is_MergeMem())
6155 old_mbase = old_base->as_MergeMem();
6156 else
6157 old_mbase = nullptr;
6158 Node* new_base = old_base;
6159
6160 // simplify stacked MergeMems in base memory
6161 if (old_mbase) new_base = old_mbase->base_memory();
6162
6163 // the base memory might contribute new slices beyond my req()
6164 if (old_mbase) grow_to_match(old_mbase);
6165
6166 // Note: We do not call verify_sparse on entry, because inputs
6167 // can normalize to the base_memory via subsume_node or similar
6168 // mechanisms. This method repairs that damage.
6169
6170 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
6171
6172 // Look at each slice.
6173 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6174 Node* old_in = in(i);
6175 // calculate the old memory value
6176 Node* old_mem = old_in;
6177 if (old_mem == empty_mem) old_mem = old_base;
6178 assert(old_mem == memory_at(i), "");
6179
6180 // maybe update (reslice) the old memory value
6181
6182 // simplify stacked MergeMems
6183 Node* new_mem = old_mem;
6184 MergeMemNode* old_mmem;
6185 if (old_mem != nullptr && old_mem->is_MergeMem())
6186 old_mmem = old_mem->as_MergeMem();
6187 else
6188 old_mmem = nullptr;
6189 if (old_mmem == this) {
6190 // This can happen if loops break up and safepoints disappear.
6191 // A merge of BotPtr (default) with a RawPtr memory derived from a
6192 // safepoint can be rewritten to a merge of the same BotPtr with
6193 // the BotPtr phi coming into the loop. If that phi disappears
6194 // also, we can end up with a self-loop of the mergemem.
6195 // In general, if loops degenerate and memory effects disappear,
6196 // a mergemem can be left looking at itself. This simply means
6197 // that the mergemem's default should be used, since there is
6198 // no longer any apparent effect on this slice.
6199 // Note: If a memory slice is a MergeMem cycle, it is unreachable
6200 // from start. Update the input to TOP.
6201 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
6202 }
6203 else if (old_mmem != nullptr) {
6204 new_mem = old_mmem->memory_at(i);
6205 }
6206 // else preceding memory was not a MergeMem
6207
6208 // maybe store down a new value
6209 Node* new_in = new_mem;
6210 if (new_in == new_base) new_in = empty_mem;
6211
6212 if (new_in != old_in) {
6213 // Warning: Do not combine this "if" with the previous "if"
6214 // A memory slice might have be be rewritten even if it is semantically
6215 // unchanged, if the base_memory value has changed.
6216 set_req_X(i, new_in, phase);
6217 progress = this; // Report progress
6218 }
6219 }
6220
6221 if (new_base != old_base) {
6222 set_req_X(Compile::AliasIdxBot, new_base, phase);
6223 // Don't use set_base_memory(new_base), because we need to update du.
6224 assert(base_memory() == new_base, "");
6225 progress = this;
6226 }
6227
6228 if( base_memory() == this ) {
6229 // a self cycle indicates this memory path is dead
6230 set_req(Compile::AliasIdxBot, empty_mem);
6231 }
6232
6233 // Resolve external cycles by calling Ideal on a MergeMem base_memory
6234 // Recursion must occur after the self cycle check above
6235 if( base_memory()->is_MergeMem() ) {
6236 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
6237 Node *m = phase->transform(new_mbase); // Rollup any cycles
6238 if( m != nullptr &&
6239 (m->is_top() ||
6240 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
6241 // propagate rollup of dead cycle to self
6242 set_req(Compile::AliasIdxBot, empty_mem);
6243 }
6244 }
6245
6246 if( base_memory() == empty_mem ) {
6247 progress = this;
6248 // Cut inputs during Parse phase only.
6249 // During Optimize phase a dead MergeMem node will be subsumed by Top.
6250 if( !can_reshape ) {
6251 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6252 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
6253 }
6254 }
6255 }
6256
6257 if( !progress && base_memory()->is_Phi() && can_reshape ) {
6258 // Check if PhiNode::Ideal's "Split phis through memory merges"
6259 // transform should be attempted. Look for this->phi->this cycle.
6260 uint merge_width = req();
6261 if (merge_width > Compile::AliasIdxRaw) {
6262 PhiNode* phi = base_memory()->as_Phi();
6263 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
6264 if (phi->in(i) == this) {
6265 phase->is_IterGVN()->_worklist.push(phi);
6266 break;
6267 }
6268 }
6269 }
6270 }
6271
6272 assert(progress || verify_sparse(), "please, no dups of base");
6273 return progress;
6274 }
6275
6276 //-------------------------set_base_memory-------------------------------------
6277 void MergeMemNode::set_base_memory(Node *new_base) {
6278 Node* empty_mem = empty_memory();
6279 set_req(Compile::AliasIdxBot, new_base);
6280 assert(memory_at(req()) == new_base, "must set default memory");
6281 // Clear out other occurrences of new_base:
6282 if (new_base != empty_mem) {
6283 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6284 if (in(i) == new_base) set_req(i, empty_mem);
6285 }
6286 }
6287 }
6288
6289 //------------------------------out_RegMask------------------------------------
6290 const RegMask &MergeMemNode::out_RegMask() const {
6291 return RegMask::EMPTY;
6292 }
6293
6294 //------------------------------dump_spec--------------------------------------
6295 #ifndef PRODUCT
6296 void MergeMemNode::dump_spec(outputStream *st) const {
6297 st->print(" {");
6298 Node* base_mem = base_memory();
6299 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
6300 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
6301 if (mem == base_mem) { st->print(" -"); continue; }
6302 st->print( " N%d:", mem->_idx );
6303 Compile::current()->get_adr_type(i)->dump_on(st);
6304 }
6305 st->print(" }");
6306 }
6307 #endif // !PRODUCT
6308
6309
6310 #ifdef ASSERT
6311 static bool might_be_same(Node* a, Node* b) {
6312 if (a == b) return true;
6313 if (!(a->is_Phi() || b->is_Phi())) return false;
6314 // phis shift around during optimization
6315 return true; // pretty stupid...
6316 }
6317
6318 // verify a narrow slice (either incoming or outgoing)
6319 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
6320 if (!VerifyAliases) return; // don't bother to verify unless requested
6321 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
6322 if (Node::in_dump()) return; // muzzle asserts when printing
6323 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
6324 assert(n != nullptr, "");
6325 // Elide intervening MergeMem's
6326 while (n->is_MergeMem()) {
6327 n = n->as_MergeMem()->memory_at(alias_idx);
6328 }
6329 Compile* C = Compile::current();
6330 const TypePtr* n_adr_type = n->adr_type();
6331 if (n == m->empty_memory()) {
6332 // Implicit copy of base_memory()
6333 } else if (n_adr_type != TypePtr::BOTTOM) {
6334 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
6335 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
6336 } else {
6337 // A few places like make_runtime_call "know" that VM calls are narrow,
6338 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
6339 bool expected_wide_mem = false;
6340 if (n == m->base_memory()) {
6341 expected_wide_mem = true;
6342 } else if (alias_idx == Compile::AliasIdxRaw ||
6343 n == m->memory_at(Compile::AliasIdxRaw)) {
6344 expected_wide_mem = true;
6345 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
6346 // memory can "leak through" calls on channels that
6347 // are write-once. Allow this also.
6348 expected_wide_mem = true;
6349 }
6350 assert(expected_wide_mem, "expected narrow slice replacement");
6351 }
6352 }
6353 #else // !ASSERT
6354 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
6355 #endif
6356
6357
6358 //-----------------------------memory_at---------------------------------------
6359 Node* MergeMemNode::memory_at(uint alias_idx) const {
6360 assert(alias_idx >= Compile::AliasIdxRaw ||
6361 (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
6362 "must avoid base_memory and AliasIdxTop");
6363
6364 // Otherwise, it is a narrow slice.
6365 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
6366 if (is_empty_memory(n)) {
6367 // the array is sparse; empty slots are the "top" node
6368 n = base_memory();
6369 assert(Node::in_dump()
6370 || n == nullptr || n->bottom_type() == Type::TOP
6371 || n->adr_type() == nullptr // address is TOP
6372 || n->adr_type() == TypePtr::BOTTOM
6373 || n->adr_type() == TypeRawPtr::BOTTOM
6374 || n->is_NarrowMemProj()
6375 || !Compile::current()->do_aliasing(),
6376 "must be a wide memory");
6377 // do_aliasing == false if we are organizing the memory states manually.
6378 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
6379 } else {
6380 // make sure the stored slice is sane
6381 #ifdef ASSERT
6382 if (VMError::is_error_reported() || Node::in_dump()) {
6383 } else if (might_be_same(n, base_memory())) {
6384 // Give it a pass: It is a mostly harmless repetition of the base.
6385 // This can arise normally from node subsumption during optimization.
6386 } else {
6387 verify_memory_slice(this, alias_idx, n);
6388 }
6389 #endif
6390 }
6391 return n;
6392 }
6393
6394 //---------------------------set_memory_at-------------------------------------
6395 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
6396 verify_memory_slice(this, alias_idx, n);
6397 Node* empty_mem = empty_memory();
6398 if (n == base_memory()) n = empty_mem; // collapse default
6399 uint need_req = alias_idx+1;
6400 if (req() < need_req) {
6401 if (n == empty_mem) return; // already the default, so do not grow me
6402 // grow the sparse array
6403 do {
6404 add_req(empty_mem);
6405 } while (req() < need_req);
6406 }
6407 set_req( alias_idx, n );
6408 }
6409
6410
6411
6412 //--------------------------iteration_setup------------------------------------
6413 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
6414 if (other != nullptr) {
6415 grow_to_match(other);
6416 // invariant: the finite support of mm2 is within mm->req()
6417 #ifdef ASSERT
6418 for (uint i = req(); i < other->req(); i++) {
6419 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
6420 }
6421 #endif
6422 }
6423 // Replace spurious copies of base_memory by top.
6424 Node* base_mem = base_memory();
6425 if (base_mem != nullptr && !base_mem->is_top()) {
6426 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
6427 if (in(i) == base_mem)
6428 set_req(i, empty_memory());
6429 }
6430 }
6431 }
6432
6433 //---------------------------grow_to_match-------------------------------------
6434 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
6435 Node* empty_mem = empty_memory();
6436 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
6437 // look for the finite support of the other memory
6438 for (uint i = other->req(); --i >= req(); ) {
6439 if (other->in(i) != empty_mem) {
6440 uint new_len = i+1;
6441 while (req() < new_len) add_req(empty_mem);
6442 break;
6443 }
6444 }
6445 }
6446
6447 //---------------------------verify_sparse-------------------------------------
6448 #ifndef PRODUCT
6449 bool MergeMemNode::verify_sparse() const {
6450 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
6451 Node* base_mem = base_memory();
6452 // The following can happen in degenerate cases, since empty==top.
6453 if (is_empty_memory(base_mem)) return true;
6454 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6455 assert(in(i) != nullptr, "sane slice");
6456 if (in(i) == base_mem) return false; // should have been the sentinel value!
6457 }
6458 return true;
6459 }
6460
6461 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
6462 Node* n;
6463 n = mm->in(idx);
6464 if (mem == n) return true; // might be empty_memory()
6465 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
6466 if (mem == n) return true;
6467 return false;
6468 }
6469 #endif // !PRODUCT