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