1 /*
2 * Copyright (c) 1997, 2025, 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.
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24 */
25
26 #include "ci/ciFlatArrayKlass.hpp"
27 #include "classfile/javaClasses.hpp"
28 #include "classfile/systemDictionary.hpp"
29 #include "compiler/compileLog.hpp"
30 #include "gc/shared/barrierSet.hpp"
31 #include "gc/shared/c2/barrierSetC2.hpp"
32 #include "gc/shared/tlab_globals.hpp"
33 #include "memory/allocation.inline.hpp"
34 #include "memory/resourceArea.hpp"
35 #include "oops/objArrayKlass.hpp"
36 #include "opto/addnode.hpp"
37 #include "opto/arraycopynode.hpp"
38 #include "opto/cfgnode.hpp"
39 #include "opto/regalloc.hpp"
40 #include "opto/compile.hpp"
41 #include "opto/connode.hpp"
42 #include "opto/convertnode.hpp"
43 #include "opto/inlinetypenode.hpp"
44 #include "opto/loopnode.hpp"
45 #include "opto/machnode.hpp"
46 #include "opto/matcher.hpp"
47 #include "opto/memnode.hpp"
48 #include "opto/mempointer.hpp"
49 #include "opto/mulnode.hpp"
50 #include "opto/narrowptrnode.hpp"
51 #include "opto/phaseX.hpp"
52 #include "opto/regmask.hpp"
53 #include "opto/rootnode.hpp"
54 #include "opto/traceMergeStoresTag.hpp"
55 #include "opto/vectornode.hpp"
56 #include "utilities/align.hpp"
57 #include "utilities/copy.hpp"
58 #include "utilities/macros.hpp"
59 #include "utilities/powerOfTwo.hpp"
60 #include "utilities/vmError.hpp"
61
62 // Portions of code courtesy of Clifford Click
63
64 // Optimization - Graph Style
65
66 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st);
67
68 //=============================================================================
69 uint MemNode::size_of() const { return sizeof(*this); }
70
71 const TypePtr *MemNode::adr_type() const {
72 Node* adr = in(Address);
73 if (adr == nullptr) return nullptr; // node is dead
74 const TypePtr* cross_check = nullptr;
75 DEBUG_ONLY(cross_check = _adr_type);
76 return calculate_adr_type(adr->bottom_type(), cross_check);
77 }
78
79 bool MemNode::check_if_adr_maybe_raw(Node* adr) {
80 if (adr != nullptr) {
81 if (adr->bottom_type()->base() == Type::RawPtr || adr->bottom_type()->base() == Type::AnyPtr) {
82 return true;
83 }
84 }
85 return false;
86 }
87
88 #ifndef PRODUCT
89 void MemNode::dump_spec(outputStream *st) const {
90 if (in(Address) == nullptr) return; // node is dead
91 #ifndef ASSERT
92 // fake the missing field
93 const TypePtr* _adr_type = nullptr;
94 if (in(Address) != nullptr)
95 _adr_type = in(Address)->bottom_type()->isa_ptr();
96 #endif
97 dump_adr_type(this, _adr_type, st);
98
99 Compile* C = Compile::current();
100 if (C->alias_type(_adr_type)->is_volatile()) {
101 st->print(" Volatile!");
102 }
103 if (_unaligned_access) {
104 st->print(" unaligned");
105 }
106 if (_mismatched_access) {
107 st->print(" mismatched");
108 }
109 if (_unsafe_access) {
110 st->print(" unsafe");
111 }
112 }
113
114 void MemNode::dump_adr_type(const Node* mem, const TypePtr* adr_type, outputStream *st) {
115 st->print(" @");
116 if (adr_type == nullptr) {
117 st->print("null");
118 } else {
119 adr_type->dump_on(st);
120 Compile* C = Compile::current();
121 Compile::AliasType* atp = nullptr;
122 if (C->have_alias_type(adr_type)) atp = C->alias_type(adr_type);
123 if (atp == nullptr)
124 st->print(", idx=?\?;");
125 else if (atp->index() == Compile::AliasIdxBot)
126 st->print(", idx=Bot;");
127 else if (atp->index() == Compile::AliasIdxTop)
128 st->print(", idx=Top;");
129 else if (atp->index() == Compile::AliasIdxRaw)
130 st->print(", idx=Raw;");
131 else {
132 ciField* field = atp->field();
133 if (field) {
134 st->print(", name=");
135 field->print_name_on(st);
136 }
137 st->print(", idx=%d;", atp->index());
138 }
139 }
140 }
141
142 extern void print_alias_types();
143
144 #endif
145
146 // Find the memory output corresponding to the fall-through path of a call
147 static Node* find_call_fallthrough_mem_output(CallNode* call) {
148 ResourceMark rm;
149 CallProjections* projs = call->extract_projections(false, false);
150 Node* res = projs->fallthrough_memproj;
151 assert(res != nullptr, "must have a fallthrough mem output");
152 return res;
153 }
154
155 // Try to find a better memory input for a load from a strict final field
156 static Node* try_optimize_strict_final_load_memory(PhaseGVN* phase, Node* adr, ProjNode*& base_local) {
157 intptr_t offset = 0;
158 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
159 if (base == nullptr) {
160 return nullptr;
161 }
162
163 Node* base_uncasted = base->uncast();
164 if (base_uncasted->is_Proj()) {
165 MultiNode* multi = base_uncasted->in(0)->as_Multi();
166 if (multi->is_Allocate()) {
167 base_local = base_uncasted->as_Proj();
168 return nullptr;
169 } else if (multi->is_Call()) {
170 // The oop is returned from a call, the memory can be the fallthrough output of the call
171 return find_call_fallthrough_mem_output(multi->as_Call());
172 } else if (multi->is_Start()) {
173 // The oop is a parameter
174 if (phase->C->method()->is_object_constructor() && base_uncasted->as_Proj()->_con == TypeFunc::Parms) {
175 // The receiver of a constructor is similar to the result of an AllocateNode
176 base_local = base_uncasted->as_Proj();
177 return nullptr;
178 } else {
179 // Use the start memory otherwise
180 return multi->proj_out(TypeFunc::Memory);
181 }
182 }
183 }
184
185 return nullptr;
186 }
187
188 // Whether a call can modify a strict final field, given that the object is allocated inside the
189 // current compilation unit, or is the first parameter when the compilation root is a constructor.
190 // This is equivalent to asking whether 'call' is a constructor invocation and the class declaring
191 // the target method is a subclass of the class declaring 'field'.
192 static bool call_can_modify_local_object(ciField* field, CallNode* call) {
193 if (!call->is_CallJava()) {
194 return false;
195 }
196
197 ciMethod* target = call->as_CallJava()->method();
198 if (target == nullptr || !target->is_object_constructor()) {
199 return false;
200 }
201
202 // If 'field' is declared in a class that is a subclass of the one declaring the constructor,
203 // then the field is set inside the constructor, else the field must be set before the
204 // constructor invocation. E.g. A field Super.x will be set during the execution of Sub::<init>,
205 // while a field Sub.y must be set before Super::<init> is invoked.
206 // We can try to be more heroic and decide if the receiver of the constructor invocation is the
207 // object from which we are loading from. This, however, may be problematic as deciding if 2
208 // nodes are definitely different may not be trivial, especially if the graph is not canonical.
209 // As a result, it is made more conservative for now.
210 assert(call->req() > TypeFunc::Parms, "constructor must have at least 1 argument");
211 return target->holder()->is_subclass_of(field->holder());
212 }
213
214 Node* MemNode::optimize_simple_memory_chain(Node* mchain, const TypeOopPtr* t_oop, Node* load, PhaseGVN* phase) {
215 assert(t_oop != nullptr, "sanity");
216 bool is_instance = t_oop->is_known_instance_field();
217
218 ciField* field = phase->C->alias_type(t_oop)->field();
219 bool is_strict_final_load = false;
220
221 // After macro expansion, an allocation may become a call, changing the memory input to the
222 // memory output of that call would be illegal. As a result, disallow this transformation after
223 // macro expansion.
224 if (phase->is_IterGVN() && phase->C->allow_macro_nodes() && load != nullptr && load->is_Load() && !load->as_Load()->is_mismatched_access()) {
225 if (EnableValhalla) {
226 if (field != nullptr && (field->holder()->is_inlinetype() || field->holder()->is_abstract_value_klass())) {
227 is_strict_final_load = true;
228 }
229 #ifdef ASSERT
230 if (t_oop->is_inlinetypeptr() && t_oop->inline_klass()->contains_field_offset(t_oop->offset())) {
231 assert(is_strict_final_load, "sanity check for basic cases");
232 }
233 #endif
234 } else {
235 is_strict_final_load = field != nullptr && t_oop->is_ptr_to_boxed_value();
236 }
237 }
238
239 if (!is_instance && !is_strict_final_load) {
240 return mchain;
241 }
242
243 Node* result = mchain;
244 ProjNode* base_local = nullptr;
245
246 if (is_strict_final_load) {
247 Node* adr = load->in(MemNode::Address);
248 assert(phase->type(adr) == t_oop, "inconsistent type");
249 Node* tmp = try_optimize_strict_final_load_memory(phase, adr, base_local);
250 if (tmp != nullptr) {
251 result = tmp;
252 }
253 }
254
255 uint instance_id = t_oop->instance_id();
256 Node* start_mem = phase->C->start()->proj_out_or_null(TypeFunc::Memory);
257 Node* prev = nullptr;
258 while (prev != result) {
259 prev = result;
260 if (result == start_mem) {
261 // start_mem is the earliest memory possible
262 break;
263 }
264
265 // skip over a call which does not affect this memory slice
266 if (result->is_Proj() && result->as_Proj()->_con == TypeFunc::Memory) {
267 Node* proj_in = result->in(0);
268 if (proj_in->is_Allocate() && proj_in->_idx == instance_id) {
269 // This is the allocation that creates the object from which we are loading from
270 break;
271 } else if (proj_in->is_Call()) {
272 // ArrayCopyNodes processed here as well
273 CallNode* call = proj_in->as_Call();
274 if (!call->may_modify(t_oop, phase)) {
275 result = call->in(TypeFunc::Memory);
276 } else if (is_strict_final_load && base_local != nullptr && !call_can_modify_local_object(field, call)) {
277 result = call->in(TypeFunc::Memory);
278 }
279 } else if (proj_in->is_Initialize()) {
280 AllocateNode* alloc = proj_in->as_Initialize()->allocation();
281 // Stop if this is the initialization for the object instance which
282 // contains this memory slice, otherwise skip over it.
283 if ((alloc == nullptr) || (alloc->_idx == instance_id)) {
284 break;
285 }
286 if (is_instance) {
287 result = proj_in->in(TypeFunc::Memory);
288 } else if (is_strict_final_load) {
289 Node* klass = alloc->in(AllocateNode::KlassNode);
290 const TypeKlassPtr* tklass = phase->type(klass)->is_klassptr();
291 if (tklass->klass_is_exact() && !tklass->exact_klass()->equals(t_oop->is_instptr()->exact_klass())) {
292 // Allocation of another type, must be another object
293 result = proj_in->in(TypeFunc::Memory);
294 } else if (base_local != nullptr && (base_local->is_Parm() || base_local->in(0) != alloc)) {
295 // Allocation of another object
296 result = proj_in->in(TypeFunc::Memory);
297 }
298 }
299 } else if (proj_in->is_MemBar()) {
300 ArrayCopyNode* ac = nullptr;
301 if (ArrayCopyNode::may_modify(t_oop, proj_in->as_MemBar(), phase, ac)) {
302 break;
303 }
304 result = proj_in->in(TypeFunc::Memory);
305 } else if (proj_in->is_top()) {
306 break; // dead code
307 } else {
308 assert(false, "unexpected projection");
309 }
310 } else if (result->is_ClearArray()) {
311 if (!is_instance || !ClearArrayNode::step_through(&result, instance_id, phase)) {
312 // Can not bypass initialization of the instance
313 // we are looking for.
314 break;
315 }
316 // Otherwise skip it (the call updated 'result' value).
317 } else if (result->is_MergeMem()) {
318 result = step_through_mergemem(phase, result->as_MergeMem(), t_oop, nullptr, tty);
319 }
320 }
321 return result;
322 }
323
324 Node *MemNode::optimize_memory_chain(Node *mchain, const TypePtr *t_adr, Node *load, PhaseGVN *phase) {
325 const TypeOopPtr* t_oop = t_adr->isa_oopptr();
326 if (t_oop == nullptr)
327 return mchain; // don't try to optimize non-oop types
328 Node* result = optimize_simple_memory_chain(mchain, t_oop, load, phase);
329 bool is_instance = t_oop->is_known_instance_field();
330 PhaseIterGVN *igvn = phase->is_IterGVN();
331 if (is_instance && igvn != nullptr && result->is_Phi()) {
332 PhiNode *mphi = result->as_Phi();
333 assert(mphi->bottom_type() == Type::MEMORY, "memory phi required");
334 const TypePtr *t = mphi->adr_type();
335 bool do_split = false;
336 // In the following cases, Load memory input can be further optimized based on
337 // its precise address type
338 if (t == TypePtr::BOTTOM || t == TypeRawPtr::BOTTOM ) {
339 do_split = true;
340 } else if (t->isa_oopptr() && !t->is_oopptr()->is_known_instance()) {
341 const TypeOopPtr* mem_t =
342 t->is_oopptr()->cast_to_exactness(true)
343 ->is_oopptr()->cast_to_ptr_type(t_oop->ptr())
344 ->is_oopptr()->cast_to_instance_id(t_oop->instance_id());
345 if (t_oop->isa_aryptr()) {
346 mem_t = mem_t->is_aryptr()
347 ->cast_to_stable(t_oop->is_aryptr()->is_stable())
348 ->cast_to_size(t_oop->is_aryptr()->size())
349 ->cast_to_not_flat(t_oop->is_aryptr()->is_not_flat())
350 ->cast_to_not_null_free(t_oop->is_aryptr()->is_not_null_free())
351 ->with_offset(t_oop->is_aryptr()->offset())
352 ->is_aryptr();
353 }
354 do_split = mem_t == t_oop;
355 }
356 if (do_split) {
357 // clone the Phi with our address type
358 result = mphi->split_out_instance(t_adr, igvn);
359 } else {
360 assert(phase->C->get_alias_index(t) == phase->C->get_alias_index(t_adr), "correct memory chain");
361 }
362 }
363 return result;
364 }
365
366 static Node *step_through_mergemem(PhaseGVN *phase, MergeMemNode *mmem, const TypePtr *tp, const TypePtr *adr_check, outputStream *st) {
367 uint alias_idx = phase->C->get_alias_index(tp);
368 Node *mem = mmem;
369 #ifdef ASSERT
370 {
371 // Check that current type is consistent with the alias index used during graph construction
372 assert(alias_idx >= Compile::AliasIdxRaw, "must not be a bad alias_idx");
373 bool consistent = adr_check == nullptr || adr_check->empty() ||
374 phase->C->must_alias(adr_check, alias_idx );
375 // Sometimes dead array references collapse to a[-1], a[-2], or a[-3]
376 if( !consistent && adr_check != nullptr && !adr_check->empty() &&
377 tp->isa_aryptr() && tp->offset() == Type::OffsetBot &&
378 adr_check->isa_aryptr() && adr_check->offset() != Type::OffsetBot &&
379 ( adr_check->offset() == arrayOopDesc::length_offset_in_bytes() ||
380 adr_check->offset() == oopDesc::klass_offset_in_bytes() ||
381 adr_check->offset() == oopDesc::mark_offset_in_bytes() ) ) {
382 // don't assert if it is dead code.
383 consistent = true;
384 }
385 if( !consistent ) {
386 st->print("alias_idx==%d, adr_check==", alias_idx);
387 if( adr_check == nullptr ) {
388 st->print("null");
389 } else {
390 adr_check->dump();
391 }
392 st->cr();
393 print_alias_types();
394 assert(consistent, "adr_check must match alias idx");
395 }
396 }
397 #endif
398 // TypeOopPtr::NOTNULL+any is an OOP with unknown offset - generally
399 // means an array I have not precisely typed yet. Do not do any
400 // alias stuff with it any time soon.
401 const TypeOopPtr *toop = tp->isa_oopptr();
402 if (tp->base() != Type::AnyPtr &&
403 !(toop &&
404 toop->isa_instptr() &&
405 toop->is_instptr()->instance_klass()->is_java_lang_Object() &&
406 toop->offset() == Type::OffsetBot)) {
407 // IGVN _delay_transform may be set to true and if that is the case and mmem
408 // is already a registered node then the validation inside transform will
409 // complain.
410 Node* m = mmem;
411 PhaseIterGVN* igvn = phase->is_IterGVN();
412 if (igvn == nullptr || !igvn->delay_transform()) {
413 // compress paths and change unreachable cycles to TOP
414 // If not, we can update the input infinitely along a MergeMem cycle
415 // Equivalent code in PhiNode::Ideal
416 m = phase->transform(mmem);
417 }
418 // If transformed to a MergeMem, get the desired slice
419 // Otherwise the returned node represents memory for every slice
420 mem = (m->is_MergeMem())? m->as_MergeMem()->memory_at(alias_idx) : m;
421 // Update input if it is progress over what we have now
422 }
423 return mem;
424 }
425
426 //--------------------------Ideal_common---------------------------------------
427 // Look for degenerate control and memory inputs. Bypass MergeMem inputs.
428 // Unhook non-raw memories from complete (macro-expanded) initializations.
429 Node *MemNode::Ideal_common(PhaseGVN *phase, bool can_reshape) {
430 // If our control input is a dead region, kill all below the region
431 Node *ctl = in(MemNode::Control);
432 if (ctl && remove_dead_region(phase, can_reshape))
433 return this;
434 ctl = in(MemNode::Control);
435 // Don't bother trying to transform a dead node
436 if (ctl && ctl->is_top()) return NodeSentinel;
437
438 PhaseIterGVN *igvn = phase->is_IterGVN();
439 // Wait if control on the worklist.
440 if (ctl && can_reshape && igvn != nullptr) {
441 Node* bol = nullptr;
442 Node* cmp = nullptr;
443 if (ctl->in(0)->is_If()) {
444 assert(ctl->is_IfTrue() || ctl->is_IfFalse(), "sanity");
445 bol = ctl->in(0)->in(1);
446 if (bol->is_Bool())
447 cmp = ctl->in(0)->in(1)->in(1);
448 }
449 if (igvn->_worklist.member(ctl) ||
450 (bol != nullptr && igvn->_worklist.member(bol)) ||
451 (cmp != nullptr && igvn->_worklist.member(cmp)) ) {
452 // This control path may be dead.
453 // Delay this memory node transformation until the control is processed.
454 igvn->_worklist.push(this);
455 return NodeSentinel; // caller will return null
456 }
457 }
458 // Ignore if memory is dead, or self-loop
459 Node *mem = in(MemNode::Memory);
460 if (phase->type( mem ) == Type::TOP) return NodeSentinel; // caller will return null
461 assert(mem != this, "dead loop in MemNode::Ideal");
462
463 if (can_reshape && igvn != nullptr && igvn->_worklist.member(mem)) {
464 // This memory slice may be dead.
465 // Delay this mem node transformation until the memory is processed.
466 igvn->_worklist.push(this);
467 return NodeSentinel; // caller will return null
468 }
469
470 Node *address = in(MemNode::Address);
471 const Type *t_adr = phase->type(address);
472 if (t_adr == Type::TOP) return NodeSentinel; // caller will return null
473
474 if (can_reshape && is_unsafe_access() && (t_adr == TypePtr::NULL_PTR)) {
475 // Unsafe off-heap access with zero address. Remove access and other control users
476 // to not confuse optimizations and add a HaltNode to fail if this is ever executed.
477 assert(ctl != nullptr, "unsafe accesses should be control dependent");
478 for (DUIterator_Fast imax, i = ctl->fast_outs(imax); i < imax; i++) {
479 Node* u = ctl->fast_out(i);
480 if (u != ctl) {
481 igvn->rehash_node_delayed(u);
482 int nb = u->replace_edge(ctl, phase->C->top(), igvn);
483 --i, imax -= nb;
484 }
485 }
486 Node* frame = igvn->transform(new ParmNode(phase->C->start(), TypeFunc::FramePtr));
487 Node* halt = igvn->transform(new HaltNode(ctl, frame, "unsafe off-heap access with zero address"));
488 phase->C->root()->add_req(halt);
489 return this;
490 }
491
492 if (can_reshape && igvn != nullptr &&
493 (igvn->_worklist.member(address) ||
494 (igvn->_worklist.size() > 0 && t_adr != adr_type())) ) {
495 // The address's base and type may change when the address is processed.
496 // Delay this mem node transformation until the address is processed.
497 igvn->_worklist.push(this);
498 return NodeSentinel; // caller will return null
499 }
500
501 // Do NOT remove or optimize the next lines: ensure a new alias index
502 // is allocated for an oop pointer type before Escape Analysis.
503 // Note: C++ will not remove it since the call has side effect.
504 if (t_adr->isa_oopptr()) {
505 int alias_idx = phase->C->get_alias_index(t_adr->is_ptr());
506 }
507
508 Node* base = nullptr;
509 if (address->is_AddP()) {
510 base = address->in(AddPNode::Base);
511 }
512 if (base != nullptr && phase->type(base)->higher_equal(TypePtr::NULL_PTR) &&
513 !t_adr->isa_rawptr()) {
514 // Note: raw address has TOP base and top->higher_equal(TypePtr::NULL_PTR) is true.
515 // Skip this node optimization if its address has TOP base.
516 return NodeSentinel; // caller will return null
517 }
518
519 // Avoid independent memory operations
520 Node* old_mem = mem;
521
522 // The code which unhooks non-raw memories from complete (macro-expanded)
523 // initializations was removed. After macro-expansion all stores caught
524 // by Initialize node became raw stores and there is no information
525 // which memory slices they modify. So it is unsafe to move any memory
526 // operation above these stores. Also in most cases hooked non-raw memories
527 // were already unhooked by using information from detect_ptr_independence()
528 // and find_previous_store().
529
530 if (mem->is_MergeMem()) {
531 MergeMemNode* mmem = mem->as_MergeMem();
532 const TypePtr *tp = t_adr->is_ptr();
533
534 mem = step_through_mergemem(phase, mmem, tp, adr_type(), tty);
535 }
536
537 if (mem != old_mem) {
538 set_req_X(MemNode::Memory, mem, phase);
539 if (phase->type(mem) == Type::TOP) return NodeSentinel;
540 return this;
541 }
542
543 // let the subclass continue analyzing...
544 return nullptr;
545 }
546
547 // Helper function for proving some simple control dominations.
548 // Attempt to prove that all control inputs of 'dom' dominate 'sub'.
549 // Already assumes that 'dom' is available at 'sub', and that 'sub'
550 // is not a constant (dominated by the method's StartNode).
551 // Used by MemNode::find_previous_store to prove that the
552 // control input of a memory operation predates (dominates)
553 // an allocation it wants to look past.
554 // Returns 'DomResult::Dominate' if all control inputs of 'dom'
555 // dominate 'sub', 'DomResult::NotDominate' if not,
556 // and 'DomResult::EncounteredDeadCode' if we can't decide due to
557 // dead code, but at the end of IGVN, we know the definite result
558 // once the dead code is cleaned up.
559 Node::DomResult MemNode::maybe_all_controls_dominate(Node* dom, Node* sub) {
560 if (dom == nullptr || dom->is_top() || sub == nullptr || sub->is_top()) {
561 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
562 }
563
564 // Check 'dom'. Skip Proj and CatchProj nodes.
565 dom = dom->find_exact_control(dom);
566 if (dom == nullptr || dom->is_top()) {
567 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
568 }
569
570 if (dom == sub) {
571 // For the case when, for example, 'sub' is Initialize and the original
572 // 'dom' is Proj node of the 'sub'.
573 return DomResult::NotDominate;
574 }
575
576 if (dom->is_Con() || dom->is_Start() || dom->is_Root() || dom == sub) {
577 return DomResult::Dominate;
578 }
579
580 // 'dom' dominates 'sub' if its control edge and control edges
581 // of all its inputs dominate or equal to sub's control edge.
582
583 // Currently 'sub' is either Allocate, Initialize or Start nodes.
584 // Or Region for the check in LoadNode::Ideal();
585 // 'sub' should have sub->in(0) != nullptr.
586 assert(sub->is_Allocate() || sub->is_Initialize() || sub->is_Start() ||
587 sub->is_Region() || sub->is_Call(), "expecting only these nodes");
588
589 // Get control edge of 'sub'.
590 Node* orig_sub = sub;
591 sub = sub->find_exact_control(sub->in(0));
592 if (sub == nullptr || sub->is_top()) {
593 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
594 }
595
596 assert(sub->is_CFG(), "expecting control");
597
598 if (sub == dom) {
599 return DomResult::Dominate;
600 }
601
602 if (sub->is_Start() || sub->is_Root()) {
603 return DomResult::NotDominate;
604 }
605
606 {
607 // Check all control edges of 'dom'.
608
609 ResourceMark rm;
610 Node_List nlist;
611 Unique_Node_List dom_list;
612
613 dom_list.push(dom);
614 bool only_dominating_controls = false;
615
616 for (uint next = 0; next < dom_list.size(); next++) {
617 Node* n = dom_list.at(next);
618 if (n == orig_sub) {
619 return DomResult::NotDominate; // One of dom's inputs dominated by sub.
620 }
621 if (!n->is_CFG() && n->pinned()) {
622 // Check only own control edge for pinned non-control nodes.
623 n = n->find_exact_control(n->in(0));
624 if (n == nullptr || n->is_top()) {
625 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
626 }
627 assert(n->is_CFG(), "expecting control");
628 dom_list.push(n);
629 } else if (n->is_Con() || n->is_Start() || n->is_Root()) {
630 only_dominating_controls = true;
631 } else if (n->is_CFG()) {
632 DomResult dom_result = n->dominates(sub, nlist);
633 if (dom_result == DomResult::Dominate) {
634 only_dominating_controls = true;
635 } else {
636 return dom_result;
637 }
638 } else {
639 // First, own control edge.
640 Node* m = n->find_exact_control(n->in(0));
641 if (m != nullptr) {
642 if (m->is_top()) {
643 return DomResult::EncounteredDeadCode; // Conservative answer for dead code
644 }
645 dom_list.push(m);
646 }
647 // Now, the rest of edges.
648 uint cnt = n->req();
649 for (uint i = 1; i < cnt; i++) {
650 m = n->find_exact_control(n->in(i));
651 if (m == nullptr || m->is_top()) {
652 continue;
653 }
654 dom_list.push(m);
655 }
656 }
657 }
658 return only_dominating_controls ? DomResult::Dominate : DomResult::NotDominate;
659 }
660 }
661
662 //---------------------detect_ptr_independence---------------------------------
663 // Used by MemNode::find_previous_store to prove that two base
664 // pointers are never equal.
665 // The pointers are accompanied by their associated allocations,
666 // if any, which have been previously discovered by the caller.
667 bool MemNode::detect_ptr_independence(Node* p1, AllocateNode* a1,
668 Node* p2, AllocateNode* a2,
669 PhaseTransform* phase) {
670 // Attempt to prove that these two pointers cannot be aliased.
671 // They may both manifestly be allocations, and they should differ.
672 // Or, if they are not both allocations, they can be distinct constants.
673 // Otherwise, one is an allocation and the other a pre-existing value.
674 if (a1 == nullptr && a2 == nullptr) { // neither an allocation
675 return (p1 != p2) && p1->is_Con() && p2->is_Con();
676 } else if (a1 != nullptr && a2 != nullptr) { // both allocations
677 return (a1 != a2);
678 } else if (a1 != nullptr) { // one allocation a1
679 // (Note: p2->is_Con implies p2->in(0)->is_Root, which dominates.)
680 return all_controls_dominate(p2, a1);
681 } else { //(a2 != null) // one allocation a2
682 return all_controls_dominate(p1, a2);
683 }
684 return false;
685 }
686
687
688 // Find an arraycopy ac that produces the memory state represented by parameter mem.
689 // Return ac if
690 // (a) can_see_stored_value=true and ac must have set the value for this load or if
691 // (b) can_see_stored_value=false and ac could have set the value for this load or if
692 // (c) can_see_stored_value=false and ac cannot have set the value for this load.
693 // In case (c) change the parameter mem to the memory input of ac to skip it
694 // when searching stored value.
695 // Otherwise return null.
696 Node* LoadNode::find_previous_arraycopy(PhaseValues* phase, Node* ld_alloc, Node*& mem, bool can_see_stored_value) const {
697 ArrayCopyNode* ac = find_array_copy_clone(ld_alloc, mem);
698 if (ac != nullptr) {
699 Node* ld_addp = in(MemNode::Address);
700 Node* src = ac->in(ArrayCopyNode::Src);
701 const TypeAryPtr* ary_t = phase->type(src)->isa_aryptr();
702
703 // This is a load from a cloned array. The corresponding arraycopy ac must
704 // have set the value for the load and we can return ac but only if the load
705 // is known to be within bounds. This is checked below.
706 if (ary_t != nullptr && ld_addp->is_AddP()) {
707 Node* ld_offs = ld_addp->in(AddPNode::Offset);
708 BasicType ary_elem = ary_t->elem()->array_element_basic_type();
709 jlong header = arrayOopDesc::base_offset_in_bytes(ary_elem);
710 jlong elemsize = type2aelembytes(ary_elem);
711
712 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
713 const TypeInt* sizetype = ary_t->size();
714
715 if (ld_offs_t->_lo >= header && ld_offs_t->_hi < (sizetype->_lo * elemsize + header)) {
716 // The load is known to be within bounds. It receives its value from ac.
717 return ac;
718 }
719 // The load is known to be out-of-bounds.
720 }
721 // The load could be out-of-bounds. It must not be hoisted but must remain
722 // dependent on the runtime range check. This is achieved by returning null.
723 } else if (mem->is_Proj() && mem->in(0) != nullptr && mem->in(0)->is_ArrayCopy()) {
724 ArrayCopyNode* ac = mem->in(0)->as_ArrayCopy();
725
726 if (ac->is_arraycopy_validated() ||
727 ac->is_copyof_validated() ||
728 ac->is_copyofrange_validated()) {
729 Node* ld_addp = in(MemNode::Address);
730 if (ld_addp->is_AddP()) {
731 Node* ld_base = ld_addp->in(AddPNode::Address);
732 Node* ld_offs = ld_addp->in(AddPNode::Offset);
733
734 Node* dest = ac->in(ArrayCopyNode::Dest);
735
736 if (dest == ld_base) {
737 const TypeX* ld_offs_t = phase->type(ld_offs)->isa_intptr_t();
738 assert(!ld_offs_t->empty(), "dead reference should be checked already");
739 // Take into account vector or unsafe access size
740 jlong ld_size_in_bytes = (jlong)memory_size();
741 jlong offset_hi = ld_offs_t->_hi + ld_size_in_bytes - 1;
742 offset_hi = MIN2(offset_hi, (jlong)(TypeX::MAX->_hi)); // Take care for overflow in 32-bit VM
743 if (ac->modifies(ld_offs_t->_lo, (intptr_t)offset_hi, phase, can_see_stored_value)) {
744 return ac;
745 }
746 if (!can_see_stored_value) {
747 mem = ac->in(TypeFunc::Memory);
748 return ac;
749 }
750 }
751 }
752 }
753 }
754 return nullptr;
755 }
756
757 ArrayCopyNode* MemNode::find_array_copy_clone(Node* ld_alloc, Node* mem) const {
758 if (mem->is_Proj() && mem->in(0) != nullptr && (mem->in(0)->Opcode() == Op_MemBarStoreStore ||
759 mem->in(0)->Opcode() == Op_MemBarCPUOrder)) {
760 if (ld_alloc != nullptr) {
761 // Check if there is an array copy for a clone
762 Node* mb = mem->in(0);
763 ArrayCopyNode* ac = nullptr;
764 if (mb->in(0) != nullptr && mb->in(0)->is_Proj() &&
765 mb->in(0)->in(0) != nullptr && mb->in(0)->in(0)->is_ArrayCopy()) {
766 ac = mb->in(0)->in(0)->as_ArrayCopy();
767 } else {
768 // Step over GC barrier when ReduceInitialCardMarks is disabled
769 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
770 Node* control_proj_ac = bs->step_over_gc_barrier(mb->in(0));
771
772 if (control_proj_ac->is_Proj() && control_proj_ac->in(0)->is_ArrayCopy()) {
773 ac = control_proj_ac->in(0)->as_ArrayCopy();
774 }
775 }
776
777 if (ac != nullptr && ac->is_clonebasic()) {
778 AllocateNode* alloc = AllocateNode::Ideal_allocation(ac->in(ArrayCopyNode::Dest));
779 if (alloc != nullptr && alloc == ld_alloc) {
780 return ac;
781 }
782 }
783 }
784 }
785 return nullptr;
786 }
787
788 // The logic for reordering loads and stores uses four steps:
789 // (a) Walk carefully past stores and initializations which we
790 // can prove are independent of this load.
791 // (b) Observe that the next memory state makes an exact match
792 // with self (load or store), and locate the relevant store.
793 // (c) Ensure that, if we were to wire self directly to the store,
794 // the optimizer would fold it up somehow.
795 // (d) Do the rewiring, and return, depending on some other part of
796 // the optimizer to fold up the load.
797 // This routine handles steps (a) and (b). Steps (c) and (d) are
798 // specific to loads and stores, so they are handled by the callers.
799 // (Currently, only LoadNode::Ideal has steps (c), (d). More later.)
800 //
801 Node* MemNode::find_previous_store(PhaseValues* phase) {
802 Node* ctrl = in(MemNode::Control);
803 Node* adr = in(MemNode::Address);
804 intptr_t offset = 0;
805 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
806 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
807
808 if (offset == Type::OffsetBot)
809 return nullptr; // cannot unalias unless there are precise offsets
810
811 const bool adr_maybe_raw = check_if_adr_maybe_raw(adr);
812 const TypeOopPtr *addr_t = adr->bottom_type()->isa_oopptr();
813
814 intptr_t size_in_bytes = memory_size();
815
816 Node* mem = in(MemNode::Memory); // start searching here...
817
818 int cnt = 50; // Cycle limiter
819 for (;;) { // While we can dance past unrelated stores...
820 if (--cnt < 0) break; // Caught in cycle or a complicated dance?
821
822 Node* prev = mem;
823 if (mem->is_Store()) {
824 Node* st_adr = mem->in(MemNode::Address);
825 intptr_t st_offset = 0;
826 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_offset);
827 if (st_base == nullptr)
828 break; // inscrutable pointer
829
830 // For raw accesses it's not enough to prove that constant offsets don't intersect.
831 // We need the bases to be the equal in order for the offset check to make sense.
832 if ((adr_maybe_raw || check_if_adr_maybe_raw(st_adr)) && st_base != base) {
833 break;
834 }
835
836 if (st_offset != offset && st_offset != Type::OffsetBot) {
837 const int MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
838 assert(mem->as_Store()->memory_size() <= MAX_STORE, "");
839 if (st_offset >= offset + size_in_bytes ||
840 st_offset <= offset - MAX_STORE ||
841 st_offset <= offset - mem->as_Store()->memory_size()) {
842 // Success: The offsets are provably independent.
843 // (You may ask, why not just test st_offset != offset and be done?
844 // The answer is that stores of different sizes can co-exist
845 // in the same sequence of RawMem effects. We sometimes initialize
846 // a whole 'tile' of array elements with a single jint or jlong.)
847 mem = mem->in(MemNode::Memory);
848 continue; // (a) advance through independent store memory
849 }
850 }
851 if (st_base != base &&
852 detect_ptr_independence(base, alloc,
853 st_base,
854 AllocateNode::Ideal_allocation(st_base),
855 phase)) {
856 // Success: The bases are provably independent.
857 mem = mem->in(MemNode::Memory);
858 continue; // (a) advance through independent store memory
859 }
860
861 // (b) At this point, if the bases or offsets do not agree, we lose,
862 // since we have not managed to prove 'this' and 'mem' independent.
863 if (st_base == base && st_offset == offset) {
864 return mem; // let caller handle steps (c), (d)
865 }
866
867 } else if (mem->is_Proj() && mem->in(0)->is_Initialize()) {
868 InitializeNode* st_init = mem->in(0)->as_Initialize();
869 AllocateNode* st_alloc = st_init->allocation();
870 if (st_alloc == nullptr) {
871 break; // something degenerated
872 }
873 bool known_identical = false;
874 bool known_independent = false;
875 if (alloc == st_alloc) {
876 known_identical = true;
877 } else if (alloc != nullptr) {
878 known_independent = true;
879 } else if (all_controls_dominate(this, st_alloc)) {
880 known_independent = true;
881 }
882
883 if (known_independent) {
884 // The bases are provably independent: Either they are
885 // manifestly distinct allocations, or else the control
886 // of this load dominates the store's allocation.
887 int alias_idx = phase->C->get_alias_index(adr_type());
888 if (alias_idx == Compile::AliasIdxRaw) {
889 mem = st_alloc->in(TypeFunc::Memory);
890 } else {
891 mem = st_init->memory(alias_idx);
892 }
893 continue; // (a) advance through independent store memory
894 }
895
896 // (b) at this point, if we are not looking at a store initializing
897 // the same allocation we are loading from, we lose.
898 if (known_identical) {
899 // From caller, can_see_stored_value will consult find_captured_store.
900 return mem; // let caller handle steps (c), (d)
901 }
902
903 } else if (find_previous_arraycopy(phase, alloc, mem, false) != nullptr) {
904 if (prev != mem) {
905 // Found an arraycopy but it doesn't affect that load
906 continue;
907 }
908 // Found an arraycopy that may affect that load
909 return mem;
910 } else if (addr_t != nullptr && addr_t->is_known_instance_field()) {
911 // Can't use optimize_simple_memory_chain() since it needs PhaseGVN.
912 if (mem->is_Proj() && mem->in(0)->is_Call()) {
913 // ArrayCopyNodes processed here as well.
914 CallNode *call = mem->in(0)->as_Call();
915 if (!call->may_modify(addr_t, phase)) {
916 mem = call->in(TypeFunc::Memory);
917 continue; // (a) advance through independent call memory
918 }
919 } else if (mem->is_Proj() && mem->in(0)->is_MemBar()) {
920 ArrayCopyNode* ac = nullptr;
921 if (ArrayCopyNode::may_modify(addr_t, mem->in(0)->as_MemBar(), phase, ac)) {
922 break;
923 }
924 mem = mem->in(0)->in(TypeFunc::Memory);
925 continue; // (a) advance through independent MemBar memory
926 } else if (mem->is_ClearArray()) {
927 if (ClearArrayNode::step_through(&mem, (uint)addr_t->instance_id(), phase)) {
928 // (the call updated 'mem' value)
929 continue; // (a) advance through independent allocation memory
930 } else {
931 // Can not bypass initialization of the instance
932 // we are looking for.
933 return mem;
934 }
935 } else if (mem->is_MergeMem()) {
936 int alias_idx = phase->C->get_alias_index(adr_type());
937 mem = mem->as_MergeMem()->memory_at(alias_idx);
938 continue; // (a) advance through independent MergeMem memory
939 }
940 }
941
942 // Unless there is an explicit 'continue', we must bail out here,
943 // because 'mem' is an inscrutable memory state (e.g., a call).
944 break;
945 }
946
947 return nullptr; // bail out
948 }
949
950 //----------------------calculate_adr_type-------------------------------------
951 // Helper function. Notices when the given type of address hits top or bottom.
952 // Also, asserts a cross-check of the type against the expected address type.
953 const TypePtr* MemNode::calculate_adr_type(const Type* t, const TypePtr* cross_check) {
954 if (t == Type::TOP) return nullptr; // does not touch memory any more?
955 #ifdef ASSERT
956 if (!VerifyAliases || VMError::is_error_reported() || Node::in_dump()) cross_check = nullptr;
957 #endif
958 const TypePtr* tp = t->isa_ptr();
959 if (tp == nullptr) {
960 assert(cross_check == nullptr || cross_check == TypePtr::BOTTOM, "expected memory type must be wide");
961 return TypePtr::BOTTOM; // touches lots of memory
962 } else {
963 #ifdef ASSERT
964 // %%%% [phh] We don't check the alias index if cross_check is
965 // TypeRawPtr::BOTTOM. Needs to be investigated.
966 if (cross_check != nullptr &&
967 cross_check != TypePtr::BOTTOM &&
968 cross_check != TypeRawPtr::BOTTOM) {
969 // Recheck the alias index, to see if it has changed (due to a bug).
970 Compile* C = Compile::current();
971 assert(C->get_alias_index(cross_check) == C->get_alias_index(tp),
972 "must stay in the original alias category");
973 // The type of the address must be contained in the adr_type,
974 // disregarding "null"-ness.
975 // (We make an exception for TypeRawPtr::BOTTOM, which is a bit bucket.)
976 const TypePtr* tp_notnull = tp->join(TypePtr::NOTNULL)->is_ptr();
977 assert(cross_check->meet(tp_notnull) == cross_check->remove_speculative(),
978 "real address must not escape from expected memory type");
979 }
980 #endif
981 return tp;
982 }
983 }
984
985 uint8_t MemNode::barrier_data(const Node* n) {
986 if (n->is_LoadStore()) {
987 return n->as_LoadStore()->barrier_data();
988 } else if (n->is_Mem()) {
989 return n->as_Mem()->barrier_data();
990 }
991 return 0;
992 }
993
994 //=============================================================================
995 // Should LoadNode::Ideal() attempt to remove control edges?
996 bool LoadNode::can_remove_control() const {
997 return !has_pinned_control_dependency();
998 }
999 uint LoadNode::size_of() const { return sizeof(*this); }
1000 bool LoadNode::cmp(const Node &n) const {
1001 LoadNode& load = (LoadNode &)n;
1002 return Type::equals(_type, load._type) &&
1003 _control_dependency == load._control_dependency &&
1004 _mo == load._mo;
1005 }
1006 const Type *LoadNode::bottom_type() const { return _type; }
1007 uint LoadNode::ideal_reg() const {
1008 return _type->ideal_reg();
1009 }
1010
1011 #ifndef PRODUCT
1012 void LoadNode::dump_spec(outputStream *st) const {
1013 MemNode::dump_spec(st);
1014 if( !Verbose && !WizardMode ) {
1015 // standard dump does this in Verbose and WizardMode
1016 st->print(" #"); _type->dump_on(st);
1017 }
1018 if (!depends_only_on_test()) {
1019 st->print(" (does not depend only on test, ");
1020 if (control_dependency() == UnknownControl) {
1021 st->print("unknown control");
1022 } else if (control_dependency() == Pinned) {
1023 st->print("pinned");
1024 } else if (adr_type() == TypeRawPtr::BOTTOM) {
1025 st->print("raw access");
1026 } else {
1027 st->print("unknown reason");
1028 }
1029 st->print(")");
1030 }
1031 }
1032 #endif
1033
1034 #ifdef ASSERT
1035 //----------------------------is_immutable_value-------------------------------
1036 // Helper function to allow a raw load without control edge for some cases
1037 bool LoadNode::is_immutable_value(Node* adr) {
1038 if (adr->is_AddP() && adr->in(AddPNode::Base)->is_top() &&
1039 adr->in(AddPNode::Address)->Opcode() == Op_ThreadLocal) {
1040
1041 jlong offset = adr->in(AddPNode::Offset)->find_intptr_t_con(-1);
1042 int offsets[] = {
1043 in_bytes(JavaThread::osthread_offset()),
1044 in_bytes(JavaThread::threadObj_offset()),
1045 in_bytes(JavaThread::vthread_offset()),
1046 in_bytes(JavaThread::scopedValueCache_offset()),
1047 };
1048
1049 for (size_t i = 0; i < sizeof offsets / sizeof offsets[0]; i++) {
1050 if (offset == offsets[i]) {
1051 return true;
1052 }
1053 }
1054 }
1055
1056 return false;
1057 }
1058 #endif
1059
1060 //----------------------------LoadNode::make-----------------------------------
1061 // Polymorphic factory method:
1062 Node* LoadNode::make(PhaseGVN& gvn, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, BasicType bt, MemOrd mo,
1063 ControlDependency control_dependency, bool require_atomic_access, bool unaligned, bool mismatched, bool unsafe, uint8_t barrier_data) {
1064 Compile* C = gvn.C;
1065
1066 // sanity check the alias category against the created node type
1067 assert(!(adr_type->isa_oopptr() &&
1068 adr_type->offset() == oopDesc::klass_offset_in_bytes()),
1069 "use LoadKlassNode instead");
1070 assert(!(adr_type->isa_aryptr() &&
1071 adr_type->offset() == arrayOopDesc::length_offset_in_bytes()),
1072 "use LoadRangeNode instead");
1073 // Check control edge of raw loads
1074 assert( ctl != nullptr || C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
1075 // oop will be recorded in oop map if load crosses safepoint
1076 rt->isa_oopptr() || is_immutable_value(adr),
1077 "raw memory operations should have control edge");
1078 LoadNode* load = nullptr;
1079 switch (bt) {
1080 case T_BOOLEAN: load = new LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1081 case T_BYTE: load = new LoadBNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1082 case T_INT: load = new LoadINode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1083 case T_CHAR: load = new LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1084 case T_SHORT: load = new LoadSNode (ctl, mem, adr, adr_type, rt->is_int(), mo, control_dependency); break;
1085 case T_LONG: load = new LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic_access); break;
1086 case T_FLOAT: load = new LoadFNode (ctl, mem, adr, adr_type, rt, mo, control_dependency); break;
1087 case T_DOUBLE: load = new LoadDNode (ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic_access); break;
1088 case T_ADDRESS: load = new LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency); break;
1089 case T_OBJECT:
1090 case T_NARROWOOP:
1091 #ifdef _LP64
1092 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
1093 load = new LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency);
1094 } else
1095 #endif
1096 {
1097 assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
1098 load = new LoadPNode(ctl, mem, adr, adr_type, rt->is_ptr(), mo, control_dependency);
1099 }
1100 break;
1101 default:
1102 ShouldNotReachHere();
1103 break;
1104 }
1105 assert(load != nullptr, "LoadNode should have been created");
1106 if (unaligned) {
1107 load->set_unaligned_access();
1108 }
1109 if (mismatched) {
1110 load->set_mismatched_access();
1111 }
1112 if (unsafe) {
1113 load->set_unsafe_access();
1114 }
1115 load->set_barrier_data(barrier_data);
1116 if (load->Opcode() == Op_LoadN) {
1117 Node* ld = gvn.transform(load);
1118 return new DecodeNNode(ld, ld->bottom_type()->make_ptr());
1119 }
1120
1121 return load;
1122 }
1123
1124 //------------------------------hash-------------------------------------------
1125 uint LoadNode::hash() const {
1126 // unroll addition of interesting fields
1127 return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address);
1128 }
1129
1130 static bool skip_through_membars(Compile::AliasType* atp, const TypeInstPtr* tp, bool eliminate_boxing) {
1131 if ((atp != nullptr) && (atp->index() >= Compile::AliasIdxRaw)) {
1132 bool non_volatile = (atp->field() != nullptr) && !atp->field()->is_volatile();
1133 bool is_stable_ary = FoldStableValues &&
1134 (tp != nullptr) && (tp->isa_aryptr() != nullptr) &&
1135 tp->isa_aryptr()->is_stable();
1136
1137 return (eliminate_boxing && non_volatile) || is_stable_ary || tp->is_inlinetypeptr();
1138 }
1139
1140 return false;
1141 }
1142
1143 LoadNode* LoadNode::pin_array_access_node() const {
1144 const TypePtr* adr_type = this->adr_type();
1145 if (adr_type != nullptr && adr_type->isa_aryptr()) {
1146 return clone_pinned();
1147 }
1148 return nullptr;
1149 }
1150
1151 // Is the value loaded previously stored by an arraycopy? If so return
1152 // a load node that reads from the source array so we may be able to
1153 // optimize out the ArrayCopy node later.
1154 Node* LoadNode::can_see_arraycopy_value(Node* st, PhaseGVN* phase) const {
1155 Node* ld_adr = in(MemNode::Address);
1156 intptr_t ld_off = 0;
1157 AllocateNode* ld_alloc = AllocateNode::Ideal_allocation(ld_adr, phase, ld_off);
1158 Node* ac = find_previous_arraycopy(phase, ld_alloc, st, true);
1159 if (ac != nullptr) {
1160 assert(ac->is_ArrayCopy(), "what kind of node can this be?");
1161
1162 Node* mem = ac->in(TypeFunc::Memory);
1163 Node* ctl = ac->in(0);
1164 Node* src = ac->in(ArrayCopyNode::Src);
1165
1166 if (!ac->as_ArrayCopy()->is_clonebasic() && !phase->type(src)->isa_aryptr()) {
1167 return nullptr;
1168 }
1169
1170 // load depends on the tests that validate the arraycopy
1171 LoadNode* ld = clone_pinned();
1172 Node* addp = in(MemNode::Address)->clone();
1173 if (ac->as_ArrayCopy()->is_clonebasic()) {
1174 assert(ld_alloc != nullptr, "need an alloc");
1175 assert(addp->is_AddP(), "address must be addp");
1176 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1177 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Base)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1178 assert(bs->step_over_gc_barrier(addp->in(AddPNode::Address)) == bs->step_over_gc_barrier(ac->in(ArrayCopyNode::Dest)), "strange pattern");
1179 addp->set_req(AddPNode::Base, src);
1180 addp->set_req(AddPNode::Address, src);
1181 } else {
1182 assert(ac->as_ArrayCopy()->is_arraycopy_validated() ||
1183 ac->as_ArrayCopy()->is_copyof_validated() ||
1184 ac->as_ArrayCopy()->is_copyofrange_validated(), "only supported cases");
1185 assert(addp->in(AddPNode::Base) == addp->in(AddPNode::Address), "should be");
1186 addp->set_req(AddPNode::Base, src);
1187 addp->set_req(AddPNode::Address, src);
1188
1189 const TypeAryPtr* ary_t = phase->type(in(MemNode::Address))->isa_aryptr();
1190 BasicType ary_elem = ary_t->isa_aryptr()->elem()->array_element_basic_type();
1191 if (is_reference_type(ary_elem, true)) ary_elem = T_OBJECT;
1192
1193 uint header = arrayOopDesc::base_offset_in_bytes(ary_elem);
1194 uint shift = ary_t->is_flat() ? ary_t->flat_log_elem_size() : exact_log2(type2aelembytes(ary_elem));
1195
1196 Node* diff = phase->transform(new SubINode(ac->in(ArrayCopyNode::SrcPos), ac->in(ArrayCopyNode::DestPos)));
1197 #ifdef _LP64
1198 diff = phase->transform(new ConvI2LNode(diff));
1199 #endif
1200 diff = phase->transform(new LShiftXNode(diff, phase->intcon(shift)));
1201
1202 Node* offset = phase->transform(new AddXNode(addp->in(AddPNode::Offset), diff));
1203 addp->set_req(AddPNode::Offset, offset);
1204 }
1205 addp = phase->transform(addp);
1206 #ifdef ASSERT
1207 const TypePtr* adr_type = phase->type(addp)->is_ptr();
1208 ld->_adr_type = adr_type;
1209 #endif
1210 ld->set_req(MemNode::Address, addp);
1211 ld->set_req(0, ctl);
1212 ld->set_req(MemNode::Memory, mem);
1213 return ld;
1214 }
1215 return nullptr;
1216 }
1217
1218 static Node* see_through_inline_type(PhaseValues* phase, const MemNode* load, Node* base, int offset) {
1219 if (!load->is_mismatched_access() && base != nullptr && base->is_InlineType() && offset > oopDesc::klass_offset_in_bytes()) {
1220 InlineTypeNode* vt = base->as_InlineType();
1221 Node* value = vt->field_value_by_offset(offset, true);
1222 assert(value != nullptr, "must see some value");
1223 return value;
1224 }
1225
1226 return nullptr;
1227 }
1228
1229 //---------------------------can_see_stored_value------------------------------
1230 // This routine exists to make sure this set of tests is done the same
1231 // everywhere. We need to make a coordinated change: first LoadNode::Ideal
1232 // will change the graph shape in a way which makes memory alive twice at the
1233 // same time (uses the Oracle model of aliasing), then some
1234 // LoadXNode::Identity will fold things back to the equivalence-class model
1235 // of aliasing.
1236 Node* MemNode::can_see_stored_value(Node* st, PhaseValues* phase) const {
1237 Node* ld_adr = in(MemNode::Address);
1238 intptr_t ld_off = 0;
1239 Node* ld_base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ld_off);
1240 // Try to see through an InlineTypeNode
1241 // LoadN is special because the input is not compressed
1242 if (Opcode() != Op_LoadN) {
1243 Node* value = see_through_inline_type(phase, this, ld_base, ld_off);
1244 if (value != nullptr) {
1245 return value;
1246 }
1247 }
1248
1249 Node* ld_alloc = AllocateNode::Ideal_allocation(ld_base);
1250 const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
1251 Compile::AliasType* atp = (tp != nullptr) ? phase->C->alias_type(tp) : nullptr;
1252 // This is more general than load from boxing objects.
1253 if (skip_through_membars(atp, tp, phase->C->eliminate_boxing())) {
1254 uint alias_idx = atp->index();
1255 Node* result = nullptr;
1256 Node* current = st;
1257 // Skip through chains of MemBarNodes checking the MergeMems for
1258 // new states for the slice of this load. Stop once any other
1259 // kind of node is encountered. Loads from final memory can skip
1260 // through any kind of MemBar but normal loads shouldn't skip
1261 // through MemBarAcquire since the could allow them to move out of
1262 // a synchronized region. It is not safe to step over MemBarCPUOrder,
1263 // because alias info above them may be inaccurate (e.g., due to
1264 // mixed/mismatched unsafe accesses).
1265 bool is_final_mem = !atp->is_rewritable();
1266 while (current->is_Proj()) {
1267 int opc = current->in(0)->Opcode();
1268 if ((is_final_mem && (opc == Op_MemBarAcquire ||
1269 opc == Op_MemBarAcquireLock ||
1270 opc == Op_LoadFence)) ||
1271 opc == Op_MemBarRelease ||
1272 opc == Op_StoreFence ||
1273 opc == Op_MemBarReleaseLock ||
1274 opc == Op_MemBarStoreStore ||
1275 opc == Op_StoreStoreFence) {
1276 Node* mem = current->in(0)->in(TypeFunc::Memory);
1277 if (mem->is_MergeMem()) {
1278 MergeMemNode* merge = mem->as_MergeMem();
1279 Node* new_st = merge->memory_at(alias_idx);
1280 if (new_st == merge->base_memory()) {
1281 // Keep searching
1282 current = new_st;
1283 continue;
1284 }
1285 // Save the new memory state for the slice and fall through
1286 // to exit.
1287 result = new_st;
1288 }
1289 }
1290 break;
1291 }
1292 if (result != nullptr) {
1293 st = result;
1294 }
1295 }
1296
1297 // Loop around twice in the case Load -> Initialize -> Store.
1298 // (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
1299 for (int trip = 0; trip <= 1; trip++) {
1300
1301 if (st->is_Store()) {
1302 Node* st_adr = st->in(MemNode::Address);
1303 if (st_adr != ld_adr) {
1304 // Try harder before giving up. Unify base pointers with casts (e.g., raw/non-raw pointers).
1305 intptr_t st_off = 0;
1306 Node* st_base = AddPNode::Ideal_base_and_offset(st_adr, phase, st_off);
1307 if (ld_base == nullptr) return nullptr;
1308 if (st_base == nullptr) return nullptr;
1309 if (!ld_base->eqv_uncast(st_base, /*keep_deps=*/true)) return nullptr;
1310 if (ld_off != st_off) return nullptr;
1311 if (ld_off == Type::OffsetBot) return nullptr;
1312 // Same base, same offset.
1313 // Possible improvement for arrays: check index value instead of absolute offset.
1314
1315 // At this point we have proven something like this setup:
1316 // B = << base >>
1317 // L = LoadQ(AddP(Check/CastPP(B), #Off))
1318 // S = StoreQ(AddP( B , #Off), V)
1319 // (Actually, we haven't yet proven the Q's are the same.)
1320 // In other words, we are loading from a casted version of
1321 // the same pointer-and-offset that we stored to.
1322 // Casted version may carry a dependency and it is respected.
1323 // Thus, we are able to replace L by V.
1324 }
1325 // Now prove that we have a LoadQ matched to a StoreQ, for some Q.
1326 if (store_Opcode() != st->Opcode()) {
1327 return nullptr;
1328 }
1329 // LoadVector/StoreVector needs additional check to ensure the types match.
1330 if (st->is_StoreVector()) {
1331 const TypeVect* in_vt = st->as_StoreVector()->vect_type();
1332 const TypeVect* out_vt = is_Load() ? as_LoadVector()->vect_type() : as_StoreVector()->vect_type();
1333 if (in_vt != out_vt) {
1334 return nullptr;
1335 }
1336 }
1337 return st->in(MemNode::ValueIn);
1338 }
1339
1340 // A load from a freshly-created object always returns zero.
1341 // (This can happen after LoadNode::Ideal resets the load's memory input
1342 // to find_captured_store, which returned InitializeNode::zero_memory.)
1343 if (st->is_Proj() && st->in(0)->is_Allocate() &&
1344 (st->in(0) == ld_alloc) &&
1345 (ld_off >= st->in(0)->as_Allocate()->minimum_header_size())) {
1346 // return a zero value for the load's basic type
1347 // (This is one of the few places where a generic PhaseTransform
1348 // can create new nodes. Think of it as lazily manifesting
1349 // virtually pre-existing constants.)
1350 Node* init_value = ld_alloc->in(AllocateNode::InitValue);
1351 if (init_value != nullptr) {
1352 // TODO 8350865 Scalar replacement does not work well for flat arrays.
1353 // Is this correct for non-all-zero init values? Don't we need field_value_by_offset?
1354 return init_value;
1355 }
1356 assert(ld_alloc->in(AllocateNode::RawInitValue) == nullptr, "init value may not be null");
1357 if (memory_type() != T_VOID) {
1358 if (ReduceBulkZeroing || find_array_copy_clone(ld_alloc, in(MemNode::Memory)) == nullptr) {
1359 // If ReduceBulkZeroing is disabled, we need to check if the allocation does not belong to an
1360 // ArrayCopyNode clone. If it does, then we cannot assume zero since the initialization is done
1361 // by the ArrayCopyNode.
1362 return phase->zerocon(memory_type());
1363 }
1364 } else {
1365 // TODO: materialize all-zero vector constant
1366 assert(!isa_Load() || as_Load()->type()->isa_vect(), "");
1367 }
1368 }
1369
1370 // A load from an initialization barrier can match a captured store.
1371 if (st->is_Proj() && st->in(0)->is_Initialize()) {
1372 InitializeNode* init = st->in(0)->as_Initialize();
1373 AllocateNode* alloc = init->allocation();
1374 if ((alloc != nullptr) && (alloc == ld_alloc)) {
1375 // examine a captured store value
1376 st = init->find_captured_store(ld_off, memory_size(), phase);
1377 if (st != nullptr) {
1378 continue; // take one more trip around
1379 }
1380 }
1381 }
1382
1383 // Load boxed value from result of valueOf() call is input parameter.
1384 if (this->is_Load() && ld_adr->is_AddP() &&
1385 (tp != nullptr) && tp->is_ptr_to_boxed_value()) {
1386 intptr_t ignore = 0;
1387 Node* base = AddPNode::Ideal_base_and_offset(ld_adr, phase, ignore);
1388 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
1389 base = bs->step_over_gc_barrier(base);
1390 if (base != nullptr && base->is_Proj() &&
1391 base->as_Proj()->_con == TypeFunc::Parms &&
1392 base->in(0)->is_CallStaticJava() &&
1393 base->in(0)->as_CallStaticJava()->is_boxing_method()) {
1394 return base->in(0)->in(TypeFunc::Parms);
1395 }
1396 }
1397
1398 break;
1399 }
1400
1401 return nullptr;
1402 }
1403
1404 //----------------------is_instance_field_load_with_local_phi------------------
1405 bool LoadNode::is_instance_field_load_with_local_phi(Node* ctrl) {
1406 if( in(Memory)->is_Phi() && in(Memory)->in(0) == ctrl &&
1407 in(Address)->is_AddP() ) {
1408 const TypeOopPtr* t_oop = in(Address)->bottom_type()->isa_oopptr();
1409 // Only instances and boxed values.
1410 if( t_oop != nullptr &&
1411 (t_oop->is_ptr_to_boxed_value() ||
1412 t_oop->is_known_instance_field()) &&
1413 t_oop->offset() != Type::OffsetBot &&
1414 t_oop->offset() != Type::OffsetTop) {
1415 return true;
1416 }
1417 }
1418 return false;
1419 }
1420
1421 //------------------------------Identity---------------------------------------
1422 // Loads are identity if previous store is to same address
1423 Node* LoadNode::Identity(PhaseGVN* phase) {
1424 // If the previous store-maker is the right kind of Store, and the store is
1425 // to the same address, then we are equal to the value stored.
1426 Node* mem = in(Memory);
1427 Node* value = can_see_stored_value(mem, phase);
1428 if( value ) {
1429 // byte, short & char stores truncate naturally.
1430 // A load has to load the truncated value which requires
1431 // some sort of masking operation and that requires an
1432 // Ideal call instead of an Identity call.
1433 if (memory_size() < BytesPerInt) {
1434 // If the input to the store does not fit with the load's result type,
1435 // it must be truncated via an Ideal call.
1436 if (!phase->type(value)->higher_equal(phase->type(this)))
1437 return this;
1438 }
1439 // (This works even when value is a Con, but LoadNode::Value
1440 // usually runs first, producing the singleton type of the Con.)
1441 if (!has_pinned_control_dependency() || value->is_Con()) {
1442 return value;
1443 } else {
1444 return this;
1445 }
1446 }
1447
1448 if (has_pinned_control_dependency()) {
1449 return this;
1450 }
1451 // Search for an existing data phi which was generated before for the same
1452 // instance's field to avoid infinite generation of phis in a loop.
1453 Node *region = mem->in(0);
1454 if (is_instance_field_load_with_local_phi(region)) {
1455 const TypeOopPtr *addr_t = in(Address)->bottom_type()->isa_oopptr();
1456 int this_index = phase->C->get_alias_index(addr_t);
1457 int this_offset = addr_t->offset();
1458 int this_iid = addr_t->instance_id();
1459 if (!addr_t->is_known_instance() &&
1460 addr_t->is_ptr_to_boxed_value()) {
1461 // Use _idx of address base (could be Phi node) for boxed values.
1462 intptr_t ignore = 0;
1463 Node* base = AddPNode::Ideal_base_and_offset(in(Address), phase, ignore);
1464 if (base == nullptr) {
1465 return this;
1466 }
1467 this_iid = base->_idx;
1468 }
1469 const Type* this_type = bottom_type();
1470 for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
1471 Node* phi = region->fast_out(i);
1472 if (phi->is_Phi() && phi != mem &&
1473 phi->as_Phi()->is_same_inst_field(this_type, (int)mem->_idx, this_iid, this_index, this_offset)) {
1474 return phi;
1475 }
1476 }
1477 }
1478
1479 return this;
1480 }
1481
1482 // Construct an equivalent unsigned load.
1483 Node* LoadNode::convert_to_unsigned_load(PhaseGVN& gvn) {
1484 BasicType bt = T_ILLEGAL;
1485 const Type* rt = nullptr;
1486 switch (Opcode()) {
1487 case Op_LoadUB: return this;
1488 case Op_LoadUS: return this;
1489 case Op_LoadB: bt = T_BOOLEAN; rt = TypeInt::UBYTE; break;
1490 case Op_LoadS: bt = T_CHAR; rt = TypeInt::CHAR; break;
1491 default:
1492 assert(false, "no unsigned variant: %s", Name());
1493 return nullptr;
1494 }
1495 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1496 raw_adr_type(), rt, bt, _mo, _control_dependency,
1497 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1498 }
1499
1500 // Construct an equivalent signed load.
1501 Node* LoadNode::convert_to_signed_load(PhaseGVN& gvn) {
1502 BasicType bt = T_ILLEGAL;
1503 const Type* rt = nullptr;
1504 switch (Opcode()) {
1505 case Op_LoadUB: bt = T_BYTE; rt = TypeInt::BYTE; break;
1506 case Op_LoadUS: bt = T_SHORT; rt = TypeInt::SHORT; break;
1507 case Op_LoadB: // fall through
1508 case Op_LoadS: // fall through
1509 case Op_LoadI: // fall through
1510 case Op_LoadL: return this;
1511 default:
1512 assert(false, "no signed variant: %s", Name());
1513 return nullptr;
1514 }
1515 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1516 raw_adr_type(), rt, bt, _mo, _control_dependency,
1517 false /*require_atomic_access*/, is_unaligned_access(), is_mismatched_access());
1518 }
1519
1520 bool LoadNode::has_reinterpret_variant(const Type* rt) {
1521 BasicType bt = rt->basic_type();
1522 switch (Opcode()) {
1523 case Op_LoadI: return (bt == T_FLOAT);
1524 case Op_LoadL: return (bt == T_DOUBLE);
1525 case Op_LoadF: return (bt == T_INT);
1526 case Op_LoadD: return (bt == T_LONG);
1527
1528 default: return false;
1529 }
1530 }
1531
1532 Node* LoadNode::convert_to_reinterpret_load(PhaseGVN& gvn, const Type* rt) {
1533 BasicType bt = rt->basic_type();
1534 assert(has_reinterpret_variant(rt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1535 bool is_mismatched = is_mismatched_access();
1536 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1537 if (raw_type == nullptr) {
1538 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1539 }
1540 const int op = Opcode();
1541 bool require_atomic_access = (op == Op_LoadL && ((LoadLNode*)this)->require_atomic_access()) ||
1542 (op == Op_LoadD && ((LoadDNode*)this)->require_atomic_access());
1543 return LoadNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1544 raw_adr_type(), rt, bt, _mo, _control_dependency,
1545 require_atomic_access, is_unaligned_access(), is_mismatched);
1546 }
1547
1548 bool StoreNode::has_reinterpret_variant(const Type* vt) {
1549 BasicType bt = vt->basic_type();
1550 switch (Opcode()) {
1551 case Op_StoreI: return (bt == T_FLOAT);
1552 case Op_StoreL: return (bt == T_DOUBLE);
1553 case Op_StoreF: return (bt == T_INT);
1554 case Op_StoreD: return (bt == T_LONG);
1555
1556 default: return false;
1557 }
1558 }
1559
1560 Node* StoreNode::convert_to_reinterpret_store(PhaseGVN& gvn, Node* val, const Type* vt) {
1561 BasicType bt = vt->basic_type();
1562 assert(has_reinterpret_variant(vt), "no reinterpret variant: %s %s", Name(), type2name(bt));
1563 const int op = Opcode();
1564 bool require_atomic_access = (op == Op_StoreL && ((StoreLNode*)this)->require_atomic_access()) ||
1565 (op == Op_StoreD && ((StoreDNode*)this)->require_atomic_access());
1566 StoreNode* st = StoreNode::make(gvn, in(MemNode::Control), in(MemNode::Memory), in(MemNode::Address),
1567 raw_adr_type(), val, bt, _mo, require_atomic_access);
1568
1569 bool is_mismatched = is_mismatched_access();
1570 const TypeRawPtr* raw_type = gvn.type(in(MemNode::Memory))->isa_rawptr();
1571 if (raw_type == nullptr) {
1572 is_mismatched = true; // conservatively match all non-raw accesses as mismatched
1573 }
1574 if (is_mismatched) {
1575 st->set_mismatched_access();
1576 }
1577 return st;
1578 }
1579
1580 // We're loading from an object which has autobox behaviour.
1581 // If this object is result of a valueOf call we'll have a phi
1582 // merging a newly allocated object and a load from the cache.
1583 // We want to replace this load with the original incoming
1584 // argument to the valueOf call.
1585 Node* LoadNode::eliminate_autobox(PhaseIterGVN* igvn) {
1586 assert(igvn->C->eliminate_boxing(), "sanity");
1587 intptr_t ignore = 0;
1588 Node* base = AddPNode::Ideal_base_and_offset(in(Address), igvn, ignore);
1589 if ((base == nullptr) || base->is_Phi()) {
1590 // Push the loads from the phi that comes from valueOf up
1591 // through it to allow elimination of the loads and the recovery
1592 // of the original value. It is done in split_through_phi().
1593 return nullptr;
1594 } else if (base->is_Load() ||
1595 (base->is_DecodeN() && base->in(1)->is_Load())) {
1596 // Eliminate the load of boxed value for integer types from the cache
1597 // array by deriving the value from the index into the array.
1598 // Capture the offset of the load and then reverse the computation.
1599
1600 // Get LoadN node which loads a boxing object from 'cache' array.
1601 if (base->is_DecodeN()) {
1602 base = base->in(1);
1603 }
1604 if (!base->in(Address)->is_AddP()) {
1605 return nullptr; // Complex address
1606 }
1607 AddPNode* address = base->in(Address)->as_AddP();
1608 Node* cache_base = address->in(AddPNode::Base);
1609 if ((cache_base != nullptr) && cache_base->is_DecodeN()) {
1610 // Get ConP node which is static 'cache' field.
1611 cache_base = cache_base->in(1);
1612 }
1613 if ((cache_base != nullptr) && cache_base->is_Con()) {
1614 const TypeAryPtr* base_type = cache_base->bottom_type()->isa_aryptr();
1615 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
1616 Node* elements[4];
1617 int shift = exact_log2(type2aelembytes(T_OBJECT));
1618 int count = address->unpack_offsets(elements, ARRAY_SIZE(elements));
1619 if (count > 0 && elements[0]->is_Con() &&
1620 (count == 1 ||
1621 (count == 2 && elements[1]->Opcode() == Op_LShiftX &&
1622 elements[1]->in(2) == igvn->intcon(shift)))) {
1623 ciObjArray* array = base_type->const_oop()->as_obj_array();
1624 // Fetch the box object cache[0] at the base of the array and get its value
1625 ciInstance* box = array->obj_at(0)->as_instance();
1626 ciInstanceKlass* ik = box->klass()->as_instance_klass();
1627 assert(ik->is_box_klass(), "sanity");
1628 assert(ik->nof_nonstatic_fields() == 1, "change following code");
1629 if (ik->nof_nonstatic_fields() == 1) {
1630 // This should be true nonstatic_field_at requires calling
1631 // nof_nonstatic_fields so check it anyway
1632 ciConstant c = box->field_value(ik->nonstatic_field_at(0));
1633 BasicType bt = c.basic_type();
1634 // Only integer types have boxing cache.
1635 assert(bt == T_BOOLEAN || bt == T_CHAR ||
1636 bt == T_BYTE || bt == T_SHORT ||
1637 bt == T_INT || bt == T_LONG, "wrong type = %s", type2name(bt));
1638 jlong cache_low = (bt == T_LONG) ? c.as_long() : c.as_int();
1639 if (cache_low != (int)cache_low) {
1640 return nullptr; // should not happen since cache is array indexed by value
1641 }
1642 jlong offset = arrayOopDesc::base_offset_in_bytes(T_OBJECT) - (cache_low << shift);
1643 if (offset != (int)offset) {
1644 return nullptr; // should not happen since cache is array indexed by value
1645 }
1646 // Add up all the offsets making of the address of the load
1647 Node* result = elements[0];
1648 for (int i = 1; i < count; i++) {
1649 result = igvn->transform(new AddXNode(result, elements[i]));
1650 }
1651 // Remove the constant offset from the address and then
1652 result = igvn->transform(new AddXNode(result, igvn->MakeConX(-(int)offset)));
1653 // remove the scaling of the offset to recover the original index.
1654 if (result->Opcode() == Op_LShiftX && result->in(2) == igvn->intcon(shift)) {
1655 // Peel the shift off directly but wrap it in a dummy node
1656 // since Ideal can't return existing nodes
1657 igvn->_worklist.push(result); // remove dead node later
1658 result = new RShiftXNode(result->in(1), igvn->intcon(0));
1659 } else if (result->is_Add() && result->in(2)->is_Con() &&
1660 result->in(1)->Opcode() == Op_LShiftX &&
1661 result->in(1)->in(2) == igvn->intcon(shift)) {
1662 // We can't do general optimization: ((X<<Z) + Y) >> Z ==> X + (Y>>Z)
1663 // but for boxing cache access we know that X<<Z will not overflow
1664 // (there is range check) so we do this optimizatrion by hand here.
1665 igvn->_worklist.push(result); // remove dead node later
1666 Node* add_con = new RShiftXNode(result->in(2), igvn->intcon(shift));
1667 result = new AddXNode(result->in(1)->in(1), igvn->transform(add_con));
1668 } else {
1669 result = new RShiftXNode(result, igvn->intcon(shift));
1670 }
1671 #ifdef _LP64
1672 if (bt != T_LONG) {
1673 result = new ConvL2INode(igvn->transform(result));
1674 }
1675 #else
1676 if (bt == T_LONG) {
1677 result = new ConvI2LNode(igvn->transform(result));
1678 }
1679 #endif
1680 // Boxing/unboxing can be done from signed & unsigned loads (e.g. LoadUB -> ... -> LoadB pair).
1681 // Need to preserve unboxing load type if it is unsigned.
1682 switch(this->Opcode()) {
1683 case Op_LoadUB:
1684 result = new AndINode(igvn->transform(result), igvn->intcon(0xFF));
1685 break;
1686 case Op_LoadUS:
1687 result = new AndINode(igvn->transform(result), igvn->intcon(0xFFFF));
1688 break;
1689 }
1690 return result;
1691 }
1692 }
1693 }
1694 }
1695 }
1696 return nullptr;
1697 }
1698
1699 static bool stable_phi(PhiNode* phi, PhaseGVN *phase) {
1700 Node* region = phi->in(0);
1701 if (region == nullptr) {
1702 return false; // Wait stable graph
1703 }
1704 uint cnt = phi->req();
1705 for (uint i = 1; i < cnt; i++) {
1706 Node* rc = region->in(i);
1707 if (rc == nullptr || phase->type(rc) == Type::TOP)
1708 return false; // Wait stable graph
1709 Node* in = phi->in(i);
1710 if (in == nullptr || phase->type(in) == Type::TOP)
1711 return false; // Wait stable graph
1712 }
1713 return true;
1714 }
1715
1716 //------------------------------split_through_phi------------------------------
1717 // Check whether a call to 'split_through_phi' would split this load through the
1718 // Phi *base*. This method is essentially a copy of the validations performed
1719 // by 'split_through_phi'. The first use of this method was in EA code as part
1720 // of simplification of allocation merges.
1721 // Some differences from original method (split_through_phi):
1722 // - If base->is_CastPP(): base = base->in(1)
1723 bool LoadNode::can_split_through_phi_base(PhaseGVN* phase) {
1724 Node* mem = in(Memory);
1725 Node* address = in(Address);
1726 intptr_t ignore = 0;
1727 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1728
1729 if (base->is_CastPP()) {
1730 base = base->in(1);
1731 }
1732
1733 if (req() > 3 || base == nullptr || !base->is_Phi()) {
1734 return false;
1735 }
1736
1737 if (!mem->is_Phi()) {
1738 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1739 return false;
1740 }
1741 } else if (base->in(0) != mem->in(0)) {
1742 if (!MemNode::all_controls_dominate(mem, base->in(0))) {
1743 return false;
1744 }
1745 }
1746
1747 return true;
1748 }
1749
1750 //------------------------------split_through_phi------------------------------
1751 // Split instance or boxed field load through Phi.
1752 Node* LoadNode::split_through_phi(PhaseGVN* phase, bool ignore_missing_instance_id) {
1753 if (req() > 3) {
1754 assert(is_LoadVector() && Opcode() != Op_LoadVector, "load has too many inputs");
1755 // LoadVector subclasses such as LoadVectorMasked have extra inputs that the logic below doesn't take into account
1756 return nullptr;
1757 }
1758 Node* mem = in(Memory);
1759 Node* address = in(Address);
1760 const TypeOopPtr *t_oop = phase->type(address)->isa_oopptr();
1761
1762 assert((t_oop != nullptr) &&
1763 (ignore_missing_instance_id ||
1764 t_oop->is_known_instance_field() ||
1765 t_oop->is_ptr_to_boxed_value()), "invalid conditions");
1766
1767 Compile* C = phase->C;
1768 intptr_t ignore = 0;
1769 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
1770 bool base_is_phi = (base != nullptr) && base->is_Phi();
1771 bool load_boxed_values = t_oop->is_ptr_to_boxed_value() && C->aggressive_unboxing() &&
1772 (base != nullptr) && (base == address->in(AddPNode::Base)) &&
1773 phase->type(base)->higher_equal(TypePtr::NOTNULL);
1774
1775 if (!((mem->is_Phi() || base_is_phi) &&
1776 (ignore_missing_instance_id || load_boxed_values || t_oop->is_known_instance_field()))) {
1777 return nullptr; // Neither memory or base are Phi
1778 }
1779
1780 if (mem->is_Phi()) {
1781 if (!stable_phi(mem->as_Phi(), phase)) {
1782 return nullptr; // Wait stable graph
1783 }
1784 uint cnt = mem->req();
1785 // Check for loop invariant memory.
1786 if (cnt == 3) {
1787 for (uint i = 1; i < cnt; i++) {
1788 Node* in = mem->in(i);
1789 Node* m = optimize_memory_chain(in, t_oop, this, phase);
1790 if (m == mem) {
1791 if (i == 1) {
1792 // if the first edge was a loop, check second edge too.
1793 // If both are replaceable - we are in an infinite loop
1794 Node *n = optimize_memory_chain(mem->in(2), t_oop, this, phase);
1795 if (n == mem) {
1796 break;
1797 }
1798 }
1799 set_req(Memory, mem->in(cnt - i));
1800 return this; // made change
1801 }
1802 }
1803 }
1804 }
1805 if (base_is_phi) {
1806 if (!stable_phi(base->as_Phi(), phase)) {
1807 return nullptr; // Wait stable graph
1808 }
1809 uint cnt = base->req();
1810 // Check for loop invariant memory.
1811 if (cnt == 3) {
1812 for (uint i = 1; i < cnt; i++) {
1813 if (base->in(i) == base) {
1814 return nullptr; // Wait stable graph
1815 }
1816 }
1817 }
1818 }
1819
1820 // Split through Phi (see original code in loopopts.cpp).
1821 assert(ignore_missing_instance_id || C->have_alias_type(t_oop), "instance should have alias type");
1822
1823 // Do nothing here if Identity will find a value
1824 // (to avoid infinite chain of value phis generation).
1825 if (this != Identity(phase)) {
1826 return nullptr;
1827 }
1828
1829 // Select Region to split through.
1830 Node* region;
1831 DomResult dom_result = DomResult::Dominate;
1832 if (!base_is_phi) {
1833 assert(mem->is_Phi(), "sanity");
1834 region = mem->in(0);
1835 // Skip if the region dominates some control edge of the address.
1836 // We will check `dom_result` later.
1837 dom_result = MemNode::maybe_all_controls_dominate(address, region);
1838 } else if (!mem->is_Phi()) {
1839 assert(base_is_phi, "sanity");
1840 region = base->in(0);
1841 // Skip if the region dominates some control edge of the memory.
1842 // We will check `dom_result` later.
1843 dom_result = MemNode::maybe_all_controls_dominate(mem, region);
1844 } else if (base->in(0) != mem->in(0)) {
1845 assert(base_is_phi && mem->is_Phi(), "sanity");
1846 dom_result = MemNode::maybe_all_controls_dominate(mem, base->in(0));
1847 if (dom_result == DomResult::Dominate) {
1848 region = base->in(0);
1849 } else {
1850 dom_result = MemNode::maybe_all_controls_dominate(address, mem->in(0));
1851 if (dom_result == DomResult::Dominate) {
1852 region = mem->in(0);
1853 }
1854 // Otherwise we encountered a complex graph.
1855 }
1856 } else {
1857 assert(base->in(0) == mem->in(0), "sanity");
1858 region = mem->in(0);
1859 }
1860
1861 PhaseIterGVN* igvn = phase->is_IterGVN();
1862 if (dom_result != DomResult::Dominate) {
1863 if (dom_result == DomResult::EncounteredDeadCode) {
1864 // There is some dead code which eventually will be removed in IGVN.
1865 // Once this is the case, we get an unambiguous dominance result.
1866 // Push the node to the worklist again until the dead code is removed.
1867 igvn->_worklist.push(this);
1868 }
1869 return nullptr;
1870 }
1871
1872 Node* phi = nullptr;
1873 const Type* this_type = this->bottom_type();
1874 if (t_oop != nullptr && (t_oop->is_known_instance_field() || load_boxed_values)) {
1875 int this_index = C->get_alias_index(t_oop);
1876 int this_offset = t_oop->offset();
1877 int this_iid = t_oop->is_known_instance_field() ? t_oop->instance_id() : base->_idx;
1878 phi = new PhiNode(region, this_type, nullptr, mem->_idx, this_iid, this_index, this_offset);
1879 } else if (ignore_missing_instance_id) {
1880 phi = new PhiNode(region, this_type, nullptr, mem->_idx);
1881 } else {
1882 return nullptr;
1883 }
1884
1885 for (uint i = 1; i < region->req(); i++) {
1886 Node* x;
1887 Node* the_clone = nullptr;
1888 Node* in = region->in(i);
1889 if (region->is_CountedLoop() && region->as_Loop()->is_strip_mined() && i == LoopNode::EntryControl &&
1890 in != nullptr && in->is_OuterStripMinedLoop()) {
1891 // No node should go in the outer strip mined loop
1892 in = in->in(LoopNode::EntryControl);
1893 }
1894 if (in == nullptr || in == C->top()) {
1895 x = C->top(); // Dead path? Use a dead data op
1896 } else {
1897 x = this->clone(); // Else clone up the data op
1898 the_clone = x; // Remember for possible deletion.
1899 // Alter data node to use pre-phi inputs
1900 if (this->in(0) == region) {
1901 x->set_req(0, in);
1902 } else {
1903 x->set_req(0, nullptr);
1904 }
1905 if (mem->is_Phi() && (mem->in(0) == region)) {
1906 x->set_req(Memory, mem->in(i)); // Use pre-Phi input for the clone.
1907 }
1908 if (address->is_Phi() && address->in(0) == region) {
1909 x->set_req(Address, address->in(i)); // Use pre-Phi input for the clone
1910 }
1911 if (base_is_phi && (base->in(0) == region)) {
1912 Node* base_x = base->in(i); // Clone address for loads from boxed objects.
1913 Node* adr_x = phase->transform(new AddPNode(base_x,base_x,address->in(AddPNode::Offset)));
1914 x->set_req(Address, adr_x);
1915 }
1916 }
1917 // Check for a 'win' on some paths
1918 const Type *t = x->Value(igvn);
1919
1920 bool singleton = t->singleton();
1921
1922 // See comments in PhaseIdealLoop::split_thru_phi().
1923 if (singleton && t == Type::TOP) {
1924 singleton &= region->is_Loop() && (i != LoopNode::EntryControl);
1925 }
1926
1927 if (singleton) {
1928 x = igvn->makecon(t);
1929 } else {
1930 // We now call Identity to try to simplify the cloned node.
1931 // Note that some Identity methods call phase->type(this).
1932 // Make sure that the type array is big enough for
1933 // our new node, even though we may throw the node away.
1934 // (This tweaking with igvn only works because x is a new node.)
1935 igvn->set_type(x, t);
1936 // If x is a TypeNode, capture any more-precise type permanently into Node
1937 // otherwise it will be not updated during igvn->transform since
1938 // igvn->type(x) is set to x->Value() already.
1939 x->raise_bottom_type(t);
1940 Node* y = x->Identity(igvn);
1941 if (y != x) {
1942 x = y;
1943 } else {
1944 y = igvn->hash_find_insert(x);
1945 if (y) {
1946 x = y;
1947 } else {
1948 // Else x is a new node we are keeping
1949 // We do not need register_new_node_with_optimizer
1950 // because set_type has already been called.
1951 igvn->_worklist.push(x);
1952 }
1953 }
1954 }
1955 if (x != the_clone && the_clone != nullptr) {
1956 igvn->remove_dead_node(the_clone);
1957 }
1958 phi->set_req(i, x);
1959 }
1960 // Record Phi
1961 igvn->register_new_node_with_optimizer(phi);
1962 return phi;
1963 }
1964
1965 AllocateNode* LoadNode::is_new_object_mark_load() const {
1966 if (Opcode() == Op_LoadX) {
1967 Node* address = in(MemNode::Address);
1968 AllocateNode* alloc = AllocateNode::Ideal_allocation(address);
1969 Node* mem = in(MemNode::Memory);
1970 if (alloc != nullptr && mem->is_Proj() &&
1971 mem->in(0) != nullptr &&
1972 mem->in(0) == alloc->initialization() &&
1973 alloc->initialization()->proj_out_or_null(0) != nullptr) {
1974 return alloc;
1975 }
1976 }
1977 return nullptr;
1978 }
1979
1980
1981 //------------------------------Ideal------------------------------------------
1982 // If the load is from Field memory and the pointer is non-null, it might be possible to
1983 // zero out the control input.
1984 // If the offset is constant and the base is an object allocation,
1985 // try to hook me up to the exact initializing store.
1986 Node *LoadNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1987 if (has_pinned_control_dependency()) {
1988 return nullptr;
1989 }
1990 Node* p = MemNode::Ideal_common(phase, can_reshape);
1991 if (p) return (p == NodeSentinel) ? nullptr : p;
1992
1993 Node* ctrl = in(MemNode::Control);
1994 Node* address = in(MemNode::Address);
1995 bool progress = false;
1996
1997 bool addr_mark = ((phase->type(address)->isa_oopptr() || phase->type(address)->isa_narrowoop()) &&
1998 phase->type(address)->is_ptr()->offset() == oopDesc::mark_offset_in_bytes());
1999
2000 // Skip up past a SafePoint control. Cannot do this for Stores because
2001 // pointer stores & cardmarks must stay on the same side of a SafePoint.
2002 if( ctrl != nullptr && ctrl->Opcode() == Op_SafePoint &&
2003 phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw &&
2004 !addr_mark &&
2005 (depends_only_on_test() || has_unknown_control_dependency())) {
2006 ctrl = ctrl->in(0);
2007 set_req(MemNode::Control,ctrl);
2008 progress = true;
2009 }
2010
2011 intptr_t ignore = 0;
2012 Node* base = AddPNode::Ideal_base_and_offset(address, phase, ignore);
2013 if (base != nullptr
2014 && phase->C->get_alias_index(phase->type(address)->is_ptr()) != Compile::AliasIdxRaw) {
2015 // Check for useless control edge in some common special cases
2016 if (in(MemNode::Control) != nullptr
2017 && !(phase->type(address)->is_inlinetypeptr() && is_mismatched_access())
2018 && can_remove_control()
2019 && phase->type(base)->higher_equal(TypePtr::NOTNULL)
2020 && all_controls_dominate(base, phase->C->start())) {
2021 // A method-invariant, non-null address (constant or 'this' argument).
2022 set_req(MemNode::Control, nullptr);
2023 progress = true;
2024 }
2025 }
2026
2027 Node* mem = in(MemNode::Memory);
2028 const TypePtr *addr_t = phase->type(address)->isa_ptr();
2029
2030 if (can_reshape && (addr_t != nullptr)) {
2031 // try to optimize our memory input
2032 Node* opt_mem = MemNode::optimize_memory_chain(mem, addr_t, this, phase);
2033 if (opt_mem != mem) {
2034 set_req_X(MemNode::Memory, opt_mem, phase);
2035 if (phase->type( opt_mem ) == Type::TOP) return nullptr;
2036 return this;
2037 }
2038 const TypeOopPtr *t_oop = addr_t->isa_oopptr();
2039 if ((t_oop != nullptr) &&
2040 (t_oop->is_known_instance_field() ||
2041 t_oop->is_ptr_to_boxed_value())) {
2042 PhaseIterGVN *igvn = phase->is_IterGVN();
2043 assert(igvn != nullptr, "must be PhaseIterGVN when can_reshape is true");
2044 if (igvn->_worklist.member(opt_mem)) {
2045 // Delay this transformation until memory Phi is processed.
2046 igvn->_worklist.push(this);
2047 return nullptr;
2048 }
2049 // Split instance field load through Phi.
2050 Node* result = split_through_phi(phase);
2051 if (result != nullptr) return result;
2052
2053 if (t_oop->is_ptr_to_boxed_value()) {
2054 Node* result = eliminate_autobox(igvn);
2055 if (result != nullptr) return result;
2056 }
2057 }
2058 }
2059
2060 // Is there a dominating load that loads the same value? Leave
2061 // anything that is not a load of a field/array element (like
2062 // barriers etc.) alone
2063 if (in(0) != nullptr && !adr_type()->isa_rawptr() && can_reshape) {
2064 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
2065 Node *use = mem->fast_out(i);
2066 if (use != this &&
2067 use->Opcode() == Opcode() &&
2068 use->in(0) != nullptr &&
2069 use->in(0) != in(0) &&
2070 use->in(Address) == in(Address)) {
2071 Node* ctl = in(0);
2072 for (int i = 0; i < 10 && ctl != nullptr; i++) {
2073 ctl = IfNode::up_one_dom(ctl);
2074 if (ctl == use->in(0)) {
2075 set_req(0, use->in(0));
2076 return this;
2077 }
2078 }
2079 }
2080 }
2081 }
2082
2083 // Check for prior store with a different base or offset; make Load
2084 // independent. Skip through any number of them. Bail out if the stores
2085 // are in an endless dead cycle and report no progress. This is a key
2086 // transform for Reflection. However, if after skipping through the Stores
2087 // we can't then fold up against a prior store do NOT do the transform as
2088 // this amounts to using the 'Oracle' model of aliasing. It leaves the same
2089 // array memory alive twice: once for the hoisted Load and again after the
2090 // bypassed Store. This situation only works if EVERYBODY who does
2091 // anti-dependence work knows how to bypass. I.e. we need all
2092 // anti-dependence checks to ask the same Oracle. Right now, that Oracle is
2093 // the alias index stuff. So instead, peek through Stores and IFF we can
2094 // fold up, do so.
2095 Node* prev_mem = find_previous_store(phase);
2096 if (prev_mem != nullptr) {
2097 Node* value = can_see_arraycopy_value(prev_mem, phase);
2098 if (value != nullptr) {
2099 return value;
2100 }
2101 }
2102 // Steps (a), (b): Walk past independent stores to find an exact match.
2103 if (prev_mem != nullptr && prev_mem != in(MemNode::Memory)) {
2104 // (c) See if we can fold up on the spot, but don't fold up here.
2105 // Fold-up might require truncation (for LoadB/LoadS/LoadUS) or
2106 // just return a prior value, which is done by Identity calls.
2107 if (can_see_stored_value(prev_mem, phase)) {
2108 // Make ready for step (d):
2109 set_req_X(MemNode::Memory, prev_mem, phase);
2110 return this;
2111 }
2112 }
2113
2114 if (progress) {
2115 return this;
2116 }
2117
2118 if (!can_reshape) {
2119 phase->record_for_igvn(this);
2120 }
2121 return nullptr;
2122 }
2123
2124 // Helper to recognize certain Klass fields which are invariant across
2125 // some group of array types (e.g., int[] or all T[] where T < Object).
2126 const Type*
2127 LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
2128 ciKlass* klass) const {
2129 assert(!UseCompactObjectHeaders || tkls->offset() != in_bytes(Klass::prototype_header_offset()),
2130 "must not happen");
2131 if (tkls->offset() == in_bytes(Klass::access_flags_offset())) {
2132 // The field is Klass::_access_flags. Return its (constant) value.
2133 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
2134 assert(Opcode() == Op_LoadUS, "must load an unsigned short from _access_flags");
2135 return TypeInt::make(klass->access_flags());
2136 }
2137 if (tkls->offset() == in_bytes(Klass::misc_flags_offset())) {
2138 // The field is Klass::_misc_flags. Return its (constant) value.
2139 // (Folds up the 2nd indirection in Reflection.getClassAccessFlags(aClassConstant).)
2140 assert(Opcode() == Op_LoadUB, "must load an unsigned byte from _misc_flags");
2141 return TypeInt::make(klass->misc_flags());
2142 }
2143 if (tkls->offset() == in_bytes(Klass::layout_helper_offset())) {
2144 // The field is Klass::_layout_helper. Return its constant value if known.
2145 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2146 return TypeInt::make(klass->layout_helper());
2147 }
2148
2149 // No match.
2150 return nullptr;
2151 }
2152
2153 //------------------------------Value-----------------------------------------
2154 const Type* LoadNode::Value(PhaseGVN* phase) const {
2155 // Either input is TOP ==> the result is TOP
2156 Node* mem = in(MemNode::Memory);
2157 const Type *t1 = phase->type(mem);
2158 if (t1 == Type::TOP) return Type::TOP;
2159 Node* adr = in(MemNode::Address);
2160 const TypePtr* tp = phase->type(adr)->isa_ptr();
2161 if (tp == nullptr || tp->empty()) return Type::TOP;
2162 int off = tp->offset();
2163 assert(off != Type::OffsetTop, "case covered by TypePtr::empty");
2164 Compile* C = phase->C;
2165
2166 // If we are loading from a freshly-allocated object, produce a zero,
2167 // if the load is provably beyond the header of the object.
2168 // (Also allow a variable load from a fresh array to produce zero.)
2169 const TypeOopPtr* tinst = tp->isa_oopptr();
2170 bool is_instance = (tinst != nullptr) && tinst->is_known_instance_field();
2171 Node* value = can_see_stored_value(mem, phase);
2172 if (value != nullptr && value->is_Con()) {
2173 assert(value->bottom_type()->higher_equal(_type), "sanity");
2174 return value->bottom_type();
2175 }
2176
2177 // Try to guess loaded type from pointer type
2178 if (tp->isa_aryptr()) {
2179 const TypeAryPtr* ary = tp->is_aryptr();
2180 const Type* t = ary->elem();
2181
2182 // Determine whether the reference is beyond the header or not, by comparing
2183 // the offset against the offset of the start of the array's data.
2184 // Different array types begin at slightly different offsets (12 vs. 16).
2185 // We choose T_BYTE as an example base type that is least restrictive
2186 // as to alignment, which will therefore produce the smallest
2187 // possible base offset.
2188 const int min_base_off = arrayOopDesc::base_offset_in_bytes(T_BYTE);
2189 const bool off_beyond_header = (off >= min_base_off);
2190
2191 // Try to constant-fold a stable array element.
2192 if (FoldStableValues && !is_mismatched_access() && ary->is_stable()) {
2193 // Make sure the reference is not into the header and the offset is constant
2194 ciObject* aobj = ary->const_oop();
2195 if (aobj != nullptr && off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
2196 int stable_dimension = (ary->stable_dimension() > 0 ? ary->stable_dimension() - 1 : 0);
2197 const Type* con_type = Type::make_constant_from_array_element(aobj->as_array(), off,
2198 stable_dimension,
2199 memory_type(), is_unsigned());
2200 if (con_type != nullptr) {
2201 return con_type;
2202 }
2203 }
2204 }
2205
2206 // Don't do this for integer types. There is only potential profit if
2207 // the element type t is lower than _type; that is, for int types, if _type is
2208 // more restrictive than t. This only happens here if one is short and the other
2209 // char (both 16 bits), and in those cases we've made an intentional decision
2210 // to use one kind of load over the other. See AndINode::Ideal and 4965907.
2211 // Also, do not try to narrow the type for a LoadKlass, regardless of offset.
2212 //
2213 // Yes, it is possible to encounter an expression like (LoadKlass p1:(AddP x x 8))
2214 // where the _gvn.type of the AddP is wider than 8. This occurs when an earlier
2215 // copy p0 of (AddP x x 8) has been proven equal to p1, and the p0 has been
2216 // subsumed by p1. If p1 is on the worklist but has not yet been re-transformed,
2217 // it is possible that p1 will have a type like Foo*[int+]:NotNull*+any.
2218 // In fact, that could have been the original type of p1, and p1 could have
2219 // had an original form like p1:(AddP x x (LShiftL quux 3)), where the
2220 // expression (LShiftL quux 3) independently optimized to the constant 8.
2221 if ((t->isa_int() == nullptr) && (t->isa_long() == nullptr)
2222 && (_type->isa_vect() == nullptr)
2223 && !ary->is_flat()
2224 && Opcode() != Op_LoadKlass && Opcode() != Op_LoadNKlass) {
2225 // t might actually be lower than _type, if _type is a unique
2226 // concrete subclass of abstract class t.
2227 if (off_beyond_header || off == Type::OffsetBot) { // is the offset beyond the header?
2228 const Type* jt = t->join_speculative(_type);
2229 // In any case, do not allow the join, per se, to empty out the type.
2230 if (jt->empty() && !t->empty()) {
2231 // This can happen if a interface-typed array narrows to a class type.
2232 jt = _type;
2233 }
2234 #ifdef ASSERT
2235 if (phase->C->eliminate_boxing() && adr->is_AddP()) {
2236 // The pointers in the autobox arrays are always non-null
2237 Node* base = adr->in(AddPNode::Base);
2238 if ((base != nullptr) && base->is_DecodeN()) {
2239 // Get LoadN node which loads IntegerCache.cache field
2240 base = base->in(1);
2241 }
2242 if ((base != nullptr) && base->is_Con()) {
2243 const TypeAryPtr* base_type = base->bottom_type()->isa_aryptr();
2244 if ((base_type != nullptr) && base_type->is_autobox_cache()) {
2245 // It could be narrow oop
2246 assert(jt->make_ptr()->ptr() == TypePtr::NotNull,"sanity");
2247 }
2248 }
2249 }
2250 #endif
2251 return jt;
2252 }
2253 }
2254 } else if (tp->base() == Type::InstPtr) {
2255 assert( off != Type::OffsetBot ||
2256 // arrays can be cast to Objects
2257 !tp->isa_instptr() ||
2258 tp->is_instptr()->instance_klass()->is_java_lang_Object() ||
2259 // Default value load
2260 tp->is_instptr()->instance_klass() == ciEnv::current()->Class_klass() ||
2261 // unsafe field access may not have a constant offset
2262 C->has_unsafe_access(),
2263 "Field accesses must be precise" );
2264 // For oop loads, we expect the _type to be precise.
2265
2266 const TypeInstPtr* tinst = tp->is_instptr();
2267 BasicType bt = memory_type();
2268
2269 // Optimize loads from constant fields.
2270 ciObject* const_oop = tinst->const_oop();
2271 if (!is_mismatched_access() && off != Type::OffsetBot && const_oop != nullptr && const_oop->is_instance()) {
2272 const Type* con_type = Type::make_constant_from_field(const_oop->as_instance(), off, is_unsigned(), bt);
2273 if (con_type != nullptr) {
2274 return con_type;
2275 }
2276 }
2277 } else if (tp->base() == Type::KlassPtr || tp->base() == Type::InstKlassPtr || tp->base() == Type::AryKlassPtr) {
2278 assert(off != Type::OffsetBot ||
2279 !tp->isa_instklassptr() ||
2280 // arrays can be cast to Objects
2281 tp->isa_instklassptr()->instance_klass()->is_java_lang_Object() ||
2282 // also allow array-loading from the primary supertype
2283 // array during subtype checks
2284 Opcode() == Op_LoadKlass,
2285 "Field accesses must be precise");
2286 // For klass/static loads, we expect the _type to be precise
2287 } else if (tp->base() == Type::RawPtr && adr->is_Load() && off == 0) {
2288 /* With mirrors being an indirect in the Klass*
2289 * the VM is now using two loads. LoadKlass(LoadP(LoadP(Klass, mirror_offset), zero_offset))
2290 * The LoadP from the Klass has a RawPtr type (see LibraryCallKit::load_mirror_from_klass).
2291 *
2292 * So check the type and klass of the node before the LoadP.
2293 */
2294 Node* adr2 = adr->in(MemNode::Address);
2295 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2296 if (tkls != nullptr && !StressReflectiveCode) {
2297 if (tkls->is_loaded() && tkls->klass_is_exact() && tkls->offset() == in_bytes(Klass::java_mirror_offset())) {
2298 ciKlass* klass = tkls->exact_klass();
2299 assert(adr->Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2300 assert(Opcode() == Op_LoadP, "must load an oop from _java_mirror");
2301 return TypeInstPtr::make(klass->java_mirror());
2302 }
2303 }
2304 }
2305
2306 const TypeKlassPtr *tkls = tp->isa_klassptr();
2307 if (tkls != nullptr) {
2308 if (tkls->is_loaded() && tkls->klass_is_exact()) {
2309 ciKlass* klass = tkls->exact_klass();
2310 // We are loading a field from a Klass metaobject whose identity
2311 // is known at compile time (the type is "exact" or "precise").
2312 // Check for fields we know are maintained as constants by the VM.
2313 if (tkls->offset() == in_bytes(Klass::super_check_offset_offset())) {
2314 // The field is Klass::_super_check_offset. Return its (constant) value.
2315 // (Folds up type checking code.)
2316 assert(Opcode() == Op_LoadI, "must load an int from _super_check_offset");
2317 return TypeInt::make(klass->super_check_offset());
2318 }
2319 if (UseCompactObjectHeaders) { // TODO: Should EnableValhalla also take this path ?
2320 if (tkls->offset() == in_bytes(Klass::prototype_header_offset())) {
2321 // The field is Klass::_prototype_header. Return its (constant) value.
2322 assert(this->Opcode() == Op_LoadX, "must load a proper type from _prototype_header");
2323 return TypeX::make(klass->prototype_header());
2324 }
2325 }
2326 // Compute index into primary_supers array
2327 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2328 // Check for overflowing; use unsigned compare to handle the negative case.
2329 if( depth < ciKlass::primary_super_limit() ) {
2330 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2331 // (Folds up type checking code.)
2332 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2333 ciKlass *ss = klass->super_of_depth(depth);
2334 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2335 }
2336 const Type* aift = load_array_final_field(tkls, klass);
2337 if (aift != nullptr) return aift;
2338 }
2339
2340 // We can still check if we are loading from the primary_supers array at a
2341 // shallow enough depth. Even though the klass is not exact, entries less
2342 // than or equal to its super depth are correct.
2343 if (tkls->is_loaded()) {
2344 ciKlass* klass = nullptr;
2345 if (tkls->isa_instklassptr()) {
2346 klass = tkls->is_instklassptr()->instance_klass();
2347 } else {
2348 int dims;
2349 const Type* inner = tkls->is_aryklassptr()->base_element_type(dims);
2350 if (inner->isa_instklassptr()) {
2351 klass = inner->is_instklassptr()->instance_klass();
2352 klass = ciObjArrayKlass::make(klass, dims);
2353 }
2354 }
2355 if (klass != nullptr) {
2356 // Compute index into primary_supers array
2357 juint depth = (tkls->offset() - in_bytes(Klass::primary_supers_offset())) / sizeof(Klass*);
2358 // Check for overflowing; use unsigned compare to handle the negative case.
2359 if (depth < ciKlass::primary_super_limit() &&
2360 depth <= klass->super_depth()) { // allow self-depth checks to handle self-check case
2361 // The field is an element of Klass::_primary_supers. Return its (constant) value.
2362 // (Folds up type checking code.)
2363 assert(Opcode() == Op_LoadKlass, "must load a klass from _primary_supers");
2364 ciKlass *ss = klass->super_of_depth(depth);
2365 return ss ? TypeKlassPtr::make(ss, Type::trust_interfaces) : TypePtr::NULL_PTR;
2366 }
2367 }
2368 }
2369
2370 // If the type is enough to determine that the thing is not an array,
2371 // we can give the layout_helper a positive interval type.
2372 // This will help short-circuit some reflective code.
2373 if (tkls->offset() == in_bytes(Klass::layout_helper_offset()) &&
2374 tkls->isa_instklassptr() && // not directly typed as an array
2375 !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
2376 ) {
2377 assert(Opcode() == Op_LoadI, "must load an int from _layout_helper");
2378 jint min_size = Klass::instance_layout_helper(oopDesc::header_size(), false);
2379 // The key property of this type is that it folds up tests
2380 // for array-ness, since it proves that the layout_helper is positive.
2381 // Thus, a generic value like the basic object layout helper works fine.
2382 return TypeInt::make(min_size, max_jint, Type::WidenMin);
2383 }
2384 }
2385
2386 bool is_vect = (_type->isa_vect() != nullptr);
2387 if (is_instance && !is_vect) {
2388 // If we have an instance type and our memory input is the
2389 // programs's initial memory state, there is no matching store,
2390 // so just return a zero of the appropriate type -
2391 // except if it is vectorized - then we have no zero constant.
2392 Node *mem = in(MemNode::Memory);
2393 if (mem->is_Parm() && mem->in(0)->is_Start()) {
2394 assert(mem->as_Parm()->_con == TypeFunc::Memory, "must be memory Parm");
2395 // TODO 8350865 Scalar replacement does not work well for flat arrays.
2396 // Escape Analysis assumes that arrays are always zeroed during allocation which is not true for null-free arrays
2397 // ConnectionGraph::split_unique_types will re-wire the memory of loads from such arrays around the allocation
2398 // TestArrays::test6 and test152 and TestBasicFunctionality::test20 are affected by this.
2399 if (tp->isa_aryptr() && tp->is_aryptr()->is_flat() && tp->is_aryptr()->is_null_free()) {
2400 intptr_t offset = 0;
2401 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2402 AllocateNode* alloc = AllocateNode::Ideal_allocation(base);
2403 if (alloc != nullptr && alloc->is_AllocateArray() && alloc->in(AllocateNode::InitValue) != nullptr) {
2404 return _type;
2405 }
2406 }
2407 return Type::get_zero_type(_type->basic_type());
2408 }
2409 }
2410 if (!UseCompactObjectHeaders) {
2411 Node* alloc = is_new_object_mark_load();
2412 if (alloc != nullptr) {
2413 if (EnableValhalla) {
2414 // The mark word may contain property bits (inline, flat, null-free)
2415 Node* klass_node = alloc->in(AllocateNode::KlassNode);
2416 const TypeKlassPtr* tkls = phase->type(klass_node)->isa_klassptr();
2417 if (tkls != nullptr && tkls->is_loaded() && tkls->klass_is_exact()) {
2418 return TypeX::make(tkls->exact_klass()->prototype_header());
2419 }
2420 } else {
2421 return TypeX::make(markWord::prototype().value());
2422 }
2423 }
2424 }
2425
2426 return _type;
2427 }
2428
2429 //------------------------------match_edge-------------------------------------
2430 // Do we Match on this edge index or not? Match only the address.
2431 uint LoadNode::match_edge(uint idx) const {
2432 return idx == MemNode::Address;
2433 }
2434
2435 //--------------------------LoadBNode::Ideal--------------------------------------
2436 //
2437 // If the previous store is to the same address as this load,
2438 // and the value stored was larger than a byte, replace this load
2439 // with the value stored truncated to a byte. If no truncation is
2440 // needed, the replacement is done in LoadNode::Identity().
2441 //
2442 Node* LoadBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2443 Node* mem = in(MemNode::Memory);
2444 Node* value = can_see_stored_value(mem,phase);
2445 if (value != nullptr) {
2446 Node* narrow = Compile::narrow_value(T_BYTE, value, _type, phase, false);
2447 if (narrow != value) {
2448 return narrow;
2449 }
2450 }
2451 // Identity call will handle the case where truncation is not needed.
2452 return LoadNode::Ideal(phase, can_reshape);
2453 }
2454
2455 const Type* LoadBNode::Value(PhaseGVN* phase) const {
2456 Node* mem = in(MemNode::Memory);
2457 Node* value = can_see_stored_value(mem,phase);
2458 if (value != nullptr && value->is_Con() &&
2459 !value->bottom_type()->higher_equal(_type)) {
2460 // If the input to the store does not fit with the load's result type,
2461 // it must be truncated. We can't delay until Ideal call since
2462 // a singleton Value is needed for split_thru_phi optimization.
2463 int con = value->get_int();
2464 return TypeInt::make((con << 24) >> 24);
2465 }
2466 return LoadNode::Value(phase);
2467 }
2468
2469 //--------------------------LoadUBNode::Ideal-------------------------------------
2470 //
2471 // If the previous store is to the same address as this load,
2472 // and the value stored was larger than a byte, replace this load
2473 // with the value stored truncated to a byte. If no truncation is
2474 // needed, the replacement is done in LoadNode::Identity().
2475 //
2476 Node* LoadUBNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2477 Node* mem = in(MemNode::Memory);
2478 Node* value = can_see_stored_value(mem, phase);
2479 if (value != nullptr) {
2480 Node* narrow = Compile::narrow_value(T_BOOLEAN, value, _type, phase, false);
2481 if (narrow != value) {
2482 return narrow;
2483 }
2484 }
2485 // Identity call will handle the case where truncation is not needed.
2486 return LoadNode::Ideal(phase, can_reshape);
2487 }
2488
2489 const Type* LoadUBNode::Value(PhaseGVN* phase) const {
2490 Node* mem = in(MemNode::Memory);
2491 Node* value = can_see_stored_value(mem,phase);
2492 if (value != nullptr && value->is_Con() &&
2493 !value->bottom_type()->higher_equal(_type)) {
2494 // If the input to the store does not fit with the load's result type,
2495 // it must be truncated. We can't delay until Ideal call since
2496 // a singleton Value is needed for split_thru_phi optimization.
2497 int con = value->get_int();
2498 return TypeInt::make(con & 0xFF);
2499 }
2500 return LoadNode::Value(phase);
2501 }
2502
2503 //--------------------------LoadUSNode::Ideal-------------------------------------
2504 //
2505 // If the previous store is to the same address as this load,
2506 // and the value stored was larger than a char, replace this load
2507 // with the value stored truncated to a char. If no truncation is
2508 // needed, the replacement is done in LoadNode::Identity().
2509 //
2510 Node* LoadUSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2511 Node* mem = in(MemNode::Memory);
2512 Node* value = can_see_stored_value(mem,phase);
2513 if (value != nullptr) {
2514 Node* narrow = Compile::narrow_value(T_CHAR, value, _type, phase, false);
2515 if (narrow != value) {
2516 return narrow;
2517 }
2518 }
2519 // Identity call will handle the case where truncation is not needed.
2520 return LoadNode::Ideal(phase, can_reshape);
2521 }
2522
2523 const Type* LoadUSNode::Value(PhaseGVN* phase) const {
2524 Node* mem = in(MemNode::Memory);
2525 Node* value = can_see_stored_value(mem,phase);
2526 if (value != nullptr && value->is_Con() &&
2527 !value->bottom_type()->higher_equal(_type)) {
2528 // If the input to the store does not fit with the load's result type,
2529 // it must be truncated. We can't delay until Ideal call since
2530 // a singleton Value is needed for split_thru_phi optimization.
2531 int con = value->get_int();
2532 return TypeInt::make(con & 0xFFFF);
2533 }
2534 return LoadNode::Value(phase);
2535 }
2536
2537 //--------------------------LoadSNode::Ideal--------------------------------------
2538 //
2539 // If the previous store is to the same address as this load,
2540 // and the value stored was larger than a short, replace this load
2541 // with the value stored truncated to a short. If no truncation is
2542 // needed, the replacement is done in LoadNode::Identity().
2543 //
2544 Node* LoadSNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2545 Node* mem = in(MemNode::Memory);
2546 Node* value = can_see_stored_value(mem,phase);
2547 if (value != nullptr) {
2548 Node* narrow = Compile::narrow_value(T_SHORT, value, _type, phase, false);
2549 if (narrow != value) {
2550 return narrow;
2551 }
2552 }
2553 // Identity call will handle the case where truncation is not needed.
2554 return LoadNode::Ideal(phase, can_reshape);
2555 }
2556
2557 const Type* LoadSNode::Value(PhaseGVN* phase) const {
2558 Node* mem = in(MemNode::Memory);
2559 Node* value = can_see_stored_value(mem,phase);
2560 if (value != nullptr && value->is_Con() &&
2561 !value->bottom_type()->higher_equal(_type)) {
2562 // If the input to the store does not fit with the load's result type,
2563 // it must be truncated. We can't delay until Ideal call since
2564 // a singleton Value is needed for split_thru_phi optimization.
2565 int con = value->get_int();
2566 return TypeInt::make((con << 16) >> 16);
2567 }
2568 return LoadNode::Value(phase);
2569 }
2570
2571 Node* LoadNNode::Ideal(PhaseGVN* phase, bool can_reshape) {
2572 // Loading from an InlineType, find the input and make an EncodeP
2573 Node* addr = in(Address);
2574 intptr_t offset;
2575 Node* base = AddPNode::Ideal_base_and_offset(addr, phase, offset);
2576 Node* value = see_through_inline_type(phase, this, base, offset);
2577 if (value != nullptr) {
2578 return new EncodePNode(value, type());
2579 }
2580
2581 return LoadNode::Ideal(phase, can_reshape);
2582 }
2583
2584 //=============================================================================
2585 //----------------------------LoadKlassNode::make------------------------------
2586 // Polymorphic factory method:
2587 Node* LoadKlassNode::make(PhaseGVN& gvn, Node* mem, Node* adr, const TypePtr* at, const TypeKlassPtr* tk, bool fold_for_arrays) {
2588 // sanity check the alias category against the created node type
2589 const TypePtr* adr_type = adr->bottom_type()->isa_ptr();
2590 assert(adr_type != nullptr, "expecting TypeKlassPtr");
2591 #ifdef _LP64
2592 if (adr_type->is_ptr_to_narrowklass()) {
2593 assert(UseCompressedClassPointers, "no compressed klasses");
2594 Node* load_klass = gvn.transform(new LoadNKlassNode(mem, adr, at, tk->make_narrowklass(), MemNode::unordered, fold_for_arrays));
2595 return new DecodeNKlassNode(load_klass, load_klass->bottom_type()->make_ptr());
2596 }
2597 #endif
2598 assert(!adr_type->is_ptr_to_narrowklass() && !adr_type->is_ptr_to_narrowoop(), "should have got back a narrow oop");
2599 return new LoadKlassNode(mem, adr, at, tk, MemNode::unordered, fold_for_arrays);
2600 }
2601
2602 //------------------------------Value------------------------------------------
2603 const Type* LoadKlassNode::Value(PhaseGVN* phase) const {
2604 return klass_value_common(phase, _fold_for_arrays);
2605 }
2606
2607 const Type* LoadNode::klass_value_common(PhaseGVN* phase, bool fold_for_arrays) const {
2608 // Either input is TOP ==> the result is TOP
2609 const Type *t1 = phase->type( in(MemNode::Memory) );
2610 if (t1 == Type::TOP) return Type::TOP;
2611 Node *adr = in(MemNode::Address);
2612 const Type *t2 = phase->type( adr );
2613 if (t2 == Type::TOP) return Type::TOP;
2614 const TypePtr *tp = t2->is_ptr();
2615 if (TypePtr::above_centerline(tp->ptr()) ||
2616 tp->ptr() == TypePtr::Null) return Type::TOP;
2617
2618 // Return a more precise klass, if possible
2619 const TypeInstPtr *tinst = tp->isa_instptr();
2620 if (tinst != nullptr) {
2621 ciInstanceKlass* ik = tinst->instance_klass();
2622 int offset = tinst->offset();
2623 if (ik == phase->C->env()->Class_klass()
2624 && (offset == java_lang_Class::klass_offset() ||
2625 offset == java_lang_Class::array_klass_offset())) {
2626 // We are loading a special hidden field from a Class mirror object,
2627 // the field which points to the VM's Klass metaobject.
2628 bool is_null_free_array = false;
2629 ciType* t = tinst->java_mirror_type(&is_null_free_array);
2630 // java_mirror_type returns non-null for compile-time Class constants.
2631 if (t != nullptr) {
2632 // constant oop => constant klass
2633 if (offset == java_lang_Class::array_klass_offset()) {
2634 if (t->is_void()) {
2635 // We cannot create a void array. Since void is a primitive type return null
2636 // klass. Users of this result need to do a null check on the returned klass.
2637 return TypePtr::NULL_PTR;
2638 }
2639 const TypeKlassPtr* tklass = TypeKlassPtr::make(ciArrayKlass::make(t), Type::trust_interfaces);
2640 if (is_null_free_array) {
2641 tklass = tklass->is_aryklassptr()->cast_to_null_free();
2642 }
2643 return tklass;
2644 }
2645 if (!t->is_klass()) {
2646 // a primitive Class (e.g., int.class) has null for a klass field
2647 return TypePtr::NULL_PTR;
2648 }
2649 // Fold up the load of the hidden field
2650 const TypeKlassPtr* tklass = TypeKlassPtr::make(t->as_klass(), Type::trust_interfaces);
2651 if (is_null_free_array) {
2652 tklass = tklass->is_aryklassptr()->cast_to_null_free();
2653 }
2654 return tklass;
2655 }
2656 // non-constant mirror, so we can't tell what's going on
2657 }
2658 if (!tinst->is_loaded())
2659 return _type; // Bail out if not loaded
2660 if (offset == oopDesc::klass_offset_in_bytes()) {
2661 return tinst->as_klass_type(true);
2662 }
2663 }
2664
2665 // Check for loading klass from an array
2666 const TypeAryPtr* tary = tp->isa_aryptr();
2667 if (tary != nullptr && fold_for_arrays &&
2668 tary->offset() == oopDesc::klass_offset_in_bytes()) {
2669 return tary->as_klass_type(true);
2670 }
2671
2672 // Check for loading klass from an array klass
2673 const TypeKlassPtr *tkls = tp->isa_klassptr();
2674 if (tkls != nullptr && !StressReflectiveCode) {
2675 if (!tkls->is_loaded())
2676 return _type; // Bail out if not loaded
2677 if (tkls->isa_aryklassptr() && tkls->is_aryklassptr()->elem()->isa_klassptr() &&
2678 tkls->offset() == in_bytes(ObjArrayKlass::element_klass_offset())) {
2679 // // Always returning precise element type is incorrect,
2680 // // e.g., element type could be object and array may contain strings
2681 // return TypeKlassPtr::make(TypePtr::Constant, elem, 0);
2682
2683 // The array's TypeKlassPtr was declared 'precise' or 'not precise'
2684 // according to the element type's subclassing.
2685 return tkls->is_aryklassptr()->elem()->isa_klassptr()->cast_to_exactness(tkls->klass_is_exact());
2686 }
2687 if (tkls->isa_instklassptr() != nullptr && tkls->klass_is_exact() &&
2688 tkls->offset() == in_bytes(Klass::super_offset())) {
2689 ciKlass* sup = tkls->is_instklassptr()->instance_klass()->super();
2690 // The field is Klass::_super. Return its (constant) value.
2691 // (Folds up the 2nd indirection in aClassConstant.getSuperClass().)
2692 return sup ? TypeKlassPtr::make(sup, Type::trust_interfaces) : TypePtr::NULL_PTR;
2693 }
2694 }
2695
2696 if (tkls != nullptr && !UseSecondarySupersCache
2697 && tkls->offset() == in_bytes(Klass::secondary_super_cache_offset())) {
2698 // Treat Klass::_secondary_super_cache as a constant when the cache is disabled.
2699 return TypePtr::NULL_PTR;
2700 }
2701
2702 // Bailout case
2703 return LoadNode::Value(phase);
2704 }
2705
2706 //------------------------------Identity---------------------------------------
2707 // To clean up reflective code, simplify k.java_mirror.as_klass to plain k.
2708 // Also feed through the klass in Allocate(...klass...)._klass.
2709 Node* LoadKlassNode::Identity(PhaseGVN* phase) {
2710 return klass_identity_common(phase);
2711 }
2712
2713 Node* LoadNode::klass_identity_common(PhaseGVN* phase) {
2714 Node* x = LoadNode::Identity(phase);
2715 if (x != this) return x;
2716
2717 // Take apart the address into an oop and offset.
2718 // Return 'this' if we cannot.
2719 Node* adr = in(MemNode::Address);
2720 intptr_t offset = 0;
2721 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2722 if (base == nullptr) return this;
2723 const TypeOopPtr* toop = phase->type(adr)->isa_oopptr();
2724 if (toop == nullptr) return this;
2725
2726 // Step over potential GC barrier for OopHandle resolve
2727 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
2728 if (bs->is_gc_barrier_node(base)) {
2729 base = bs->step_over_gc_barrier(base);
2730 }
2731
2732 // We can fetch the klass directly through an AllocateNode.
2733 // This works even if the klass is not constant (clone or newArray).
2734 if (offset == oopDesc::klass_offset_in_bytes()) {
2735 Node* allocated_klass = AllocateNode::Ideal_klass(base, phase);
2736 if (allocated_klass != nullptr) {
2737 return allocated_klass;
2738 }
2739 }
2740
2741 // Simplify k.java_mirror.as_klass to plain k, where k is a Klass*.
2742 // See inline_native_Class_query for occurrences of these patterns.
2743 // Java Example: x.getClass().isAssignableFrom(y)
2744 //
2745 // This improves reflective code, often making the Class
2746 // mirror go completely dead. (Current exception: Class
2747 // mirrors may appear in debug info, but we could clean them out by
2748 // introducing a new debug info operator for Klass.java_mirror).
2749
2750 if (toop->isa_instptr() && toop->is_instptr()->instance_klass() == phase->C->env()->Class_klass()
2751 && offset == java_lang_Class::klass_offset()) {
2752 if (base->is_Load()) {
2753 Node* base2 = base->in(MemNode::Address);
2754 if (base2->is_Load()) { /* direct load of a load which is the OopHandle */
2755 Node* adr2 = base2->in(MemNode::Address);
2756 const TypeKlassPtr* tkls = phase->type(adr2)->isa_klassptr();
2757 if (tkls != nullptr && !tkls->empty()
2758 && (tkls->isa_instklassptr() || tkls->isa_aryklassptr())
2759 && adr2->is_AddP()
2760 ) {
2761 int mirror_field = in_bytes(Klass::java_mirror_offset());
2762 if (tkls->offset() == mirror_field) {
2763 return adr2->in(AddPNode::Base);
2764 }
2765 }
2766 }
2767 }
2768 }
2769
2770 return this;
2771 }
2772
2773 LoadNode* LoadNode::clone_pinned() const {
2774 LoadNode* ld = clone()->as_Load();
2775 ld->_control_dependency = UnknownControl;
2776 return ld;
2777 }
2778
2779
2780 //------------------------------Value------------------------------------------
2781 const Type* LoadNKlassNode::Value(PhaseGVN* phase) const {
2782 const Type *t = klass_value_common(phase, _fold_for_arrays);
2783 if (t == Type::TOP)
2784 return t;
2785
2786 return t->make_narrowklass();
2787 }
2788
2789 //------------------------------Identity---------------------------------------
2790 // To clean up reflective code, simplify k.java_mirror.as_klass to narrow k.
2791 // Also feed through the klass in Allocate(...klass...)._klass.
2792 Node* LoadNKlassNode::Identity(PhaseGVN* phase) {
2793 Node *x = klass_identity_common(phase);
2794
2795 const Type *t = phase->type( x );
2796 if( t == Type::TOP ) return x;
2797 if( t->isa_narrowklass()) return x;
2798 assert (!t->isa_narrowoop(), "no narrow oop here");
2799
2800 return phase->transform(new EncodePKlassNode(x, t->make_narrowklass()));
2801 }
2802
2803 //------------------------------Value-----------------------------------------
2804 const Type* LoadRangeNode::Value(PhaseGVN* phase) const {
2805 // Either input is TOP ==> the result is TOP
2806 const Type *t1 = phase->type( in(MemNode::Memory) );
2807 if( t1 == Type::TOP ) return Type::TOP;
2808 Node *adr = in(MemNode::Address);
2809 const Type *t2 = phase->type( adr );
2810 if( t2 == Type::TOP ) return Type::TOP;
2811 const TypePtr *tp = t2->is_ptr();
2812 if (TypePtr::above_centerline(tp->ptr())) return Type::TOP;
2813 const TypeAryPtr *tap = tp->isa_aryptr();
2814 if( !tap ) return _type;
2815 return tap->size();
2816 }
2817
2818 //-------------------------------Ideal---------------------------------------
2819 // Feed through the length in AllocateArray(...length...)._length.
2820 Node *LoadRangeNode::Ideal(PhaseGVN *phase, bool can_reshape) {
2821 Node* p = MemNode::Ideal_common(phase, can_reshape);
2822 if (p) return (p == NodeSentinel) ? nullptr : p;
2823
2824 // Take apart the address into an oop and offset.
2825 // Return 'this' if we cannot.
2826 Node* adr = in(MemNode::Address);
2827 intptr_t offset = 0;
2828 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2829 if (base == nullptr) return nullptr;
2830 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2831 if (tary == nullptr) return nullptr;
2832
2833 // We can fetch the length directly through an AllocateArrayNode.
2834 // This works even if the length is not constant (clone or newArray).
2835 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2836 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2837 if (alloc != nullptr) {
2838 Node* allocated_length = alloc->Ideal_length();
2839 Node* len = alloc->make_ideal_length(tary, phase);
2840 if (allocated_length != len) {
2841 // New CastII improves on this.
2842 return len;
2843 }
2844 }
2845 }
2846
2847 return nullptr;
2848 }
2849
2850 //------------------------------Identity---------------------------------------
2851 // Feed through the length in AllocateArray(...length...)._length.
2852 Node* LoadRangeNode::Identity(PhaseGVN* phase) {
2853 Node* x = LoadINode::Identity(phase);
2854 if (x != this) return x;
2855
2856 // Take apart the address into an oop and offset.
2857 // Return 'this' if we cannot.
2858 Node* adr = in(MemNode::Address);
2859 intptr_t offset = 0;
2860 Node* base = AddPNode::Ideal_base_and_offset(adr, phase, offset);
2861 if (base == nullptr) return this;
2862 const TypeAryPtr* tary = phase->type(adr)->isa_aryptr();
2863 if (tary == nullptr) return this;
2864
2865 // We can fetch the length directly through an AllocateArrayNode.
2866 // This works even if the length is not constant (clone or newArray).
2867 if (offset == arrayOopDesc::length_offset_in_bytes()) {
2868 AllocateArrayNode* alloc = AllocateArrayNode::Ideal_array_allocation(base);
2869 if (alloc != nullptr) {
2870 Node* allocated_length = alloc->Ideal_length();
2871 // Do not allow make_ideal_length to allocate a CastII node.
2872 Node* len = alloc->make_ideal_length(tary, phase, false);
2873 if (allocated_length == len) {
2874 // Return allocated_length only if it would not be improved by a CastII.
2875 return allocated_length;
2876 }
2877 }
2878 }
2879
2880 return this;
2881
2882 }
2883
2884 //=============================================================================
2885 //---------------------------StoreNode::make-----------------------------------
2886 // Polymorphic factory method:
2887 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) {
2888 assert((mo == unordered || mo == release), "unexpected");
2889 Compile* C = gvn.C;
2890 assert(C->get_alias_index(adr_type) != Compile::AliasIdxRaw ||
2891 ctl != nullptr, "raw memory operations should have control edge");
2892
2893 switch (bt) {
2894 case T_BOOLEAN: val = gvn.transform(new AndINode(val, gvn.intcon(0x1))); // Fall through to T_BYTE case
2895 case T_BYTE: return new StoreBNode(ctl, mem, adr, adr_type, val, mo);
2896 case T_INT: return new StoreINode(ctl, mem, adr, adr_type, val, mo);
2897 case T_CHAR:
2898 case T_SHORT: return new StoreCNode(ctl, mem, adr, adr_type, val, mo);
2899 case T_LONG: return new StoreLNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2900 case T_FLOAT: return new StoreFNode(ctl, mem, adr, adr_type, val, mo);
2901 case T_DOUBLE: return new StoreDNode(ctl, mem, adr, adr_type, val, mo, require_atomic_access);
2902 case T_METADATA:
2903 case T_ADDRESS:
2904 case T_OBJECT:
2905 #ifdef _LP64
2906 if (adr->bottom_type()->is_ptr_to_narrowoop()) {
2907 val = gvn.transform(new EncodePNode(val, val->bottom_type()->make_narrowoop()));
2908 return new StoreNNode(ctl, mem, adr, adr_type, val, mo);
2909 } else if (adr->bottom_type()->is_ptr_to_narrowklass() ||
2910 (UseCompressedClassPointers && val->bottom_type()->isa_klassptr() &&
2911 adr->bottom_type()->isa_rawptr())) {
2912 val = gvn.transform(new EncodePKlassNode(val, val->bottom_type()->make_narrowklass()));
2913 return new StoreNKlassNode(ctl, mem, adr, adr_type, val, mo);
2914 }
2915 #endif
2916 {
2917 return new StorePNode(ctl, mem, adr, adr_type, val, mo);
2918 }
2919 default:
2920 ShouldNotReachHere();
2921 return (StoreNode*)nullptr;
2922 }
2923 }
2924
2925 //--------------------------bottom_type----------------------------------------
2926 const Type *StoreNode::bottom_type() const {
2927 return Type::MEMORY;
2928 }
2929
2930 //------------------------------hash-------------------------------------------
2931 uint StoreNode::hash() const {
2932 // unroll addition of interesting fields
2933 //return (uintptr_t)in(Control) + (uintptr_t)in(Memory) + (uintptr_t)in(Address) + (uintptr_t)in(ValueIn);
2934
2935 // Since they are not commoned, do not hash them:
2936 return NO_HASH;
2937 }
2938
2939 // Link together multiple stores (B/S/C/I) into a longer one.
2940 //
2941 // Example: _store = StoreB[i+3]
2942 //
2943 // RangeCheck[i+0] RangeCheck[i+0]
2944 // StoreB[i+0]
2945 // RangeCheck[i+3] RangeCheck[i+3]
2946 // StoreB[i+1] --> pass: fail:
2947 // StoreB[i+2] StoreI[i+0] StoreB[i+0]
2948 // StoreB[i+3]
2949 //
2950 // The 4 StoreB are merged into a single StoreI node. We have to be careful with RangeCheck[i+1]: before
2951 // the optimization, if this RangeCheck[i+1] fails, then we execute only StoreB[i+0], and then trap. After
2952 // the optimization, the new StoreI[i+0] is on the passing path of RangeCheck[i+3], and StoreB[i+0] on the
2953 // failing path.
2954 //
2955 // Note: For normal array stores, every store at first has a RangeCheck. But they can be removed with:
2956 // - RCE (RangeCheck Elimination): the RangeChecks in the loop are hoisted out and before the loop,
2957 // and possibly no RangeChecks remain between the stores.
2958 // - RangeCheck smearing: the earlier RangeChecks are adjusted such that they cover later RangeChecks,
2959 // and those later RangeChecks can be removed. Example:
2960 //
2961 // RangeCheck[i+0] RangeCheck[i+0] <- before first store
2962 // StoreB[i+0] StoreB[i+0] <- first store
2963 // RangeCheck[i+1] --> smeared --> RangeCheck[i+3] <- only RC between first and last store
2964 // StoreB[i+1] StoreB[i+1] <- second store
2965 // RangeCheck[i+2] --> removed
2966 // StoreB[i+2] StoreB[i+2]
2967 // RangeCheck[i+3] --> removed
2968 // StoreB[i+3] StoreB[i+3] <- last store
2969 //
2970 // Thus, it is a common pattern that between the first and last store in a chain
2971 // of adjacent stores there remains exactly one RangeCheck, located between the
2972 // first and the second store (e.g. RangeCheck[i+3]).
2973 //
2974 class MergePrimitiveStores : public StackObj {
2975 private:
2976 PhaseGVN* const _phase;
2977 StoreNode* const _store;
2978 // State machine with initial state Unknown
2979 // Allowed transitions:
2980 // Unknown -> Const
2981 // Unknown -> Platform
2982 // Unknown -> Reverse
2983 // Unknown -> NotAdjacent
2984 // Const -> Const
2985 // Const -> NotAdjacent
2986 // Platform -> Platform
2987 // Platform -> NotAdjacent
2988 // Reverse -> Reverse
2989 // Reverse -> NotAdjacent
2990 // NotAdjacent -> NotAdjacent
2991 enum ValueOrder : uint8_t {
2992 Unknown, // Initial state
2993 Const, // Input values are const
2994 Platform, // Platform order
2995 Reverse, // Reverse platform order
2996 NotAdjacent // Not adjacent
2997 };
2998 ValueOrder _value_order;
2999
3000 NOT_PRODUCT( const CHeapBitMap &_trace_tags; )
3001
3002 public:
3003 MergePrimitiveStores(PhaseGVN* phase, StoreNode* store) :
3004 _phase(phase), _store(store), _value_order(ValueOrder::Unknown)
3005 NOT_PRODUCT( COMMA _trace_tags(Compile::current()->directive()->trace_merge_stores_tags()) )
3006 {}
3007
3008 StoreNode* run();
3009
3010 private:
3011 bool is_compatible_store(const StoreNode* other_store) const;
3012 bool is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const;
3013 bool is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const;
3014 static bool is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase);
3015 enum CFGStatus { SuccessNoRangeCheck, SuccessWithRangeCheck, Failure };
3016 static CFGStatus cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store);
3017
3018 class Status {
3019 private:
3020 StoreNode* _found_store;
3021 bool _found_range_check;
3022
3023 Status(StoreNode* found_store, bool found_range_check)
3024 : _found_store(found_store), _found_range_check(found_range_check) {}
3025
3026 public:
3027 StoreNode* found_store() const { return _found_store; }
3028 bool found_range_check() const { return _found_range_check; }
3029 static Status make_failure() { return Status(nullptr, false); }
3030
3031 static Status make(StoreNode* found_store, const CFGStatus cfg_status) {
3032 if (cfg_status == CFGStatus::Failure) {
3033 return Status::make_failure();
3034 }
3035 return Status(found_store, cfg_status == CFGStatus::SuccessWithRangeCheck);
3036 }
3037
3038 #ifndef PRODUCT
3039 void print_on(outputStream* st) const {
3040 if (_found_store == nullptr) {
3041 st->print_cr("None");
3042 } else {
3043 st->print_cr("Found[%d %s, %s]", _found_store->_idx, _found_store->Name(),
3044 _found_range_check ? "RC" : "no-RC");
3045 }
3046 }
3047 #endif
3048 };
3049
3050 enum ValueOrder find_adjacent_input_value_order(const Node* n1, const Node* n2, const int memory_size) const;
3051 Status find_adjacent_use_store(const StoreNode* def_store) const;
3052 Status find_adjacent_def_store(const StoreNode* use_store) const;
3053 Status find_use_store(const StoreNode* def_store) const;
3054 Status find_def_store(const StoreNode* use_store) const;
3055 Status find_use_store_unidirectional(const StoreNode* def_store) const;
3056 Status find_def_store_unidirectional(const StoreNode* use_store) const;
3057
3058 void collect_merge_list(Node_List& merge_list) const;
3059 Node* make_merged_input_value(const Node_List& merge_list);
3060 StoreNode* make_merged_store(const Node_List& merge_list, Node* merged_input_value);
3061
3062 #ifndef PRODUCT
3063 // Access to TraceMergeStores tags
3064 bool is_trace(TraceMergeStores::Tag tag) const {
3065 return _trace_tags.at(tag);
3066 }
3067
3068 bool is_trace_basic() const {
3069 return is_trace(TraceMergeStores::Tag::BASIC);
3070 }
3071
3072 bool is_trace_pointer_parsing() const {
3073 return is_trace(TraceMergeStores::Tag::POINTER_PARSING);
3074 }
3075
3076 bool is_trace_pointer_aliasing() const {
3077 return is_trace(TraceMergeStores::Tag::POINTER_ALIASING);
3078 }
3079
3080 bool is_trace_pointer_adjacency() const {
3081 return is_trace(TraceMergeStores::Tag::POINTER_ADJACENCY);
3082 }
3083
3084 bool is_trace_success() const {
3085 return is_trace(TraceMergeStores::Tag::SUCCESS);
3086 }
3087 #endif
3088
3089 NOT_PRODUCT( void trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const; )
3090 };
3091
3092 StoreNode* MergePrimitiveStores::run() {
3093 // Check for B/S/C/I
3094 int opc = _store->Opcode();
3095 if (opc != Op_StoreB && opc != Op_StoreC && opc != Op_StoreI) {
3096 return nullptr;
3097 }
3098
3099 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] MergePrimitiveStores::run: "); _store->dump(); })
3100
3101 // The _store must be the "last" store in a chain. If we find a use we could merge with
3102 // then that use or a store further down is the "last" store.
3103 Status status_use = find_adjacent_use_store(_store);
3104 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect no use: "); status_use.print_on(tty); })
3105 if (status_use.found_store() != nullptr) {
3106 return nullptr;
3107 }
3108
3109 // Check if we can merge with at least one def, so that we have at least 2 stores to merge.
3110 Status status_def = find_adjacent_def_store(_store);
3111 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] expect def: "); status_def.print_on(tty); })
3112 Node* def_store = status_def.found_store();
3113 if (def_store == nullptr) {
3114 return nullptr;
3115 }
3116
3117 // Initialize value order
3118 _value_order = find_adjacent_input_value_order(def_store->in(MemNode::ValueIn),
3119 _store->in(MemNode::ValueIn),
3120 _store->memory_size());
3121 assert(_value_order != ValueOrder::NotAdjacent && _value_order != ValueOrder::Unknown, "Order should be checked");
3122
3123 ResourceMark rm;
3124 Node_List merge_list;
3125 collect_merge_list(merge_list);
3126
3127 Node* merged_input_value = make_merged_input_value(merge_list);
3128 if (merged_input_value == nullptr) { return nullptr; }
3129
3130 StoreNode* merged_store = make_merged_store(merge_list, merged_input_value);
3131
3132 NOT_PRODUCT( if (is_trace_success()) { trace(merge_list, merged_input_value, merged_store); } )
3133
3134 return merged_store;
3135 }
3136
3137 // Check compatibility between _store and other_store.
3138 bool MergePrimitiveStores::is_compatible_store(const StoreNode* other_store) const {
3139 int opc = _store->Opcode();
3140 assert(opc == Op_StoreB || opc == Op_StoreC || opc == Op_StoreI, "precondition");
3141
3142 if (other_store == nullptr ||
3143 _store->Opcode() != other_store->Opcode()) {
3144 return false;
3145 }
3146
3147 return true;
3148 }
3149
3150 bool MergePrimitiveStores::is_adjacent_pair(const StoreNode* use_store, const StoreNode* def_store) const {
3151 if (!is_adjacent_input_pair(def_store->in(MemNode::ValueIn),
3152 use_store->in(MemNode::ValueIn),
3153 def_store->memory_size())) {
3154 return false;
3155 }
3156
3157 ResourceMark rm;
3158 #ifndef PRODUCT
3159 const TraceMemPointer trace(is_trace_pointer_parsing(),
3160 is_trace_pointer_aliasing(),
3161 is_trace_pointer_adjacency(),
3162 true);
3163 #endif
3164 const MemPointer pointer_use(use_store NOT_PRODUCT(COMMA trace));
3165 const MemPointer pointer_def(def_store NOT_PRODUCT(COMMA trace));
3166 return pointer_def.is_adjacent_to_and_before(pointer_use);
3167 }
3168
3169 // Check input values n1 and n2 can be merged and return the value order
3170 MergePrimitiveStores::ValueOrder MergePrimitiveStores::find_adjacent_input_value_order(const Node* n1, const Node* n2,
3171 const int memory_size) const {
3172 // Pattern: [n1 = ConI, n2 = ConI]
3173 if (n1->Opcode() == Op_ConI && n2->Opcode() == Op_ConI) {
3174 return ValueOrder::Const;
3175 }
3176
3177 Node const *base_n2;
3178 jint shift_n2;
3179 if (!is_con_RShift(n2, base_n2, shift_n2, _phase)) {
3180 return ValueOrder::NotAdjacent;
3181 }
3182 Node const *base_n1;
3183 jint shift_n1;
3184 if (!is_con_RShift(n1, base_n1, shift_n1, _phase)) {
3185 return ValueOrder::NotAdjacent;
3186 }
3187
3188 int bits_per_store = memory_size * 8;
3189 if (base_n1 != base_n2 ||
3190 abs(shift_n1 - shift_n2) != bits_per_store ||
3191 shift_n1 % bits_per_store != 0) {
3192 // Values are not adjacent
3193 return ValueOrder::NotAdjacent;
3194 }
3195
3196 // Detect value order
3197 #ifdef VM_LITTLE_ENDIAN
3198 return shift_n1 < shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3199 : ValueOrder::Reverse; // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3200 #else
3201 return shift_n1 > shift_n2 ? ValueOrder::Platform // Pattern: [n1 = base >> (shift + memory_size), n2 = base >> shift]
3202 : ValueOrder::Reverse; // Pattern: [n1 = base >> shift, n2 = base >> (shift + memory_size)]
3203 #endif
3204 }
3205
3206 bool MergePrimitiveStores::is_adjacent_input_pair(const Node* n1, const Node* n2, const int memory_size) const {
3207 ValueOrder input_value_order = find_adjacent_input_value_order(n1, n2, memory_size);
3208
3209 switch (input_value_order) {
3210 case ValueOrder::NotAdjacent:
3211 return false;
3212 case ValueOrder::Reverse:
3213 if (memory_size != 1 ||
3214 !Matcher::match_rule_supported(Op_ReverseBytesS) ||
3215 !Matcher::match_rule_supported(Op_ReverseBytesI) ||
3216 !Matcher::match_rule_supported(Op_ReverseBytesL)) {
3217 // ReverseBytes are not supported by platform
3218 return false;
3219 }
3220 // fall-through.
3221 case ValueOrder::Const:
3222 case ValueOrder::Platform:
3223 if (_value_order == ValueOrder::Unknown) {
3224 // Initial state is Unknown, and we find a valid input value order
3225 return true;
3226 }
3227 // The value order can not be changed
3228 return _value_order == input_value_order;
3229 case ValueOrder::Unknown:
3230 default:
3231 ShouldNotReachHere();
3232 }
3233 return false;
3234 }
3235
3236 // Detect pattern: n = base_out >> shift_out
3237 bool MergePrimitiveStores::is_con_RShift(const Node* n, Node const*& base_out, jint& shift_out, PhaseGVN* phase) {
3238 assert(n != nullptr, "precondition");
3239
3240 int opc = n->Opcode();
3241 if (opc == Op_ConvL2I) {
3242 n = n->in(1);
3243 opc = n->Opcode();
3244 }
3245
3246 if ((opc == Op_RShiftI ||
3247 opc == Op_RShiftL ||
3248 opc == Op_URShiftI ||
3249 opc == Op_URShiftL) &&
3250 n->in(2)->is_ConI()) {
3251 base_out = n->in(1);
3252 shift_out = n->in(2)->get_int();
3253 // The shift must be positive:
3254 return shift_out >= 0;
3255 }
3256
3257 if (phase->type(n)->isa_int() != nullptr ||
3258 phase->type(n)->isa_long() != nullptr) {
3259 // (base >> 0)
3260 base_out = n;
3261 shift_out = 0;
3262 return true;
3263 }
3264 return false;
3265 }
3266
3267 // Check if there is nothing between the two stores, except optionally a RangeCheck leading to an uncommon trap.
3268 MergePrimitiveStores::CFGStatus MergePrimitiveStores::cfg_status_for_pair(const StoreNode* use_store, const StoreNode* def_store) {
3269 assert(use_store->in(MemNode::Memory) == def_store, "use-def relationship");
3270
3271 Node* ctrl_use = use_store->in(MemNode::Control);
3272 Node* ctrl_def = def_store->in(MemNode::Control);
3273 if (ctrl_use == nullptr || ctrl_def == nullptr) {
3274 return CFGStatus::Failure;
3275 }
3276
3277 if (ctrl_use == ctrl_def) {
3278 // Same ctrl -> no RangeCheck in between.
3279 // Check: use_store must be the only use of def_store.
3280 if (def_store->outcnt() > 1) {
3281 return CFGStatus::Failure;
3282 }
3283 return CFGStatus::SuccessNoRangeCheck;
3284 }
3285
3286 // Different ctrl -> could have RangeCheck in between.
3287 // Check: 1. def_store only has these uses: use_store and MergeMem for uncommon trap, and
3288 // 2. ctrl separated by RangeCheck.
3289 if (def_store->outcnt() != 2) {
3290 return CFGStatus::Failure; // Cannot have exactly these uses: use_store and MergeMem for uncommon trap.
3291 }
3292 int use_store_out_idx = def_store->raw_out(0) == use_store ? 0 : 1;
3293 Node* merge_mem = def_store->raw_out(1 - use_store_out_idx)->isa_MergeMem();
3294 if (merge_mem == nullptr ||
3295 merge_mem->outcnt() != 1) {
3296 return CFGStatus::Failure; // Does not have MergeMem for uncommon trap.
3297 }
3298 if (!ctrl_use->is_IfProj() ||
3299 !ctrl_use->in(0)->is_RangeCheck() ||
3300 ctrl_use->in(0)->outcnt() != 2) {
3301 return CFGStatus::Failure; // Not RangeCheck.
3302 }
3303 ProjNode* other_proj = ctrl_use->as_IfProj()->other_if_proj();
3304 Node* trap = other_proj->is_uncommon_trap_proj(Deoptimization::Reason_range_check);
3305 if (trap != merge_mem->unique_out() ||
3306 ctrl_use->in(0)->in(0) != ctrl_def) {
3307 return CFGStatus::Failure; // Not RangeCheck with merge_mem leading to uncommon trap.
3308 }
3309
3310 return CFGStatus::SuccessWithRangeCheck;
3311 }
3312
3313 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_use_store(const StoreNode* def_store) const {
3314 Status status_use = find_use_store(def_store);
3315 StoreNode* use_store = status_use.found_store();
3316 if (use_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3317 return Status::make_failure();
3318 }
3319 return status_use;
3320 }
3321
3322 MergePrimitiveStores::Status MergePrimitiveStores::find_adjacent_def_store(const StoreNode* use_store) const {
3323 Status status_def = find_def_store(use_store);
3324 StoreNode* def_store = status_def.found_store();
3325 if (def_store != nullptr && !is_adjacent_pair(use_store, def_store)) {
3326 return Status::make_failure();
3327 }
3328 return status_def;
3329 }
3330
3331 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store(const StoreNode* def_store) const {
3332 Status status_use = find_use_store_unidirectional(def_store);
3333
3334 #ifdef ASSERT
3335 StoreNode* use_store = status_use.found_store();
3336 if (use_store != nullptr) {
3337 Status status_def = find_def_store_unidirectional(use_store);
3338 assert(status_def.found_store() == def_store &&
3339 status_def.found_range_check() == status_use.found_range_check(),
3340 "find_use_store and find_def_store must be symmetric");
3341 }
3342 #endif
3343
3344 return status_use;
3345 }
3346
3347 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store(const StoreNode* use_store) const {
3348 Status status_def = find_def_store_unidirectional(use_store);
3349
3350 #ifdef ASSERT
3351 StoreNode* def_store = status_def.found_store();
3352 if (def_store != nullptr) {
3353 Status status_use = find_use_store_unidirectional(def_store);
3354 assert(status_use.found_store() == use_store &&
3355 status_use.found_range_check() == status_def.found_range_check(),
3356 "find_use_store and find_def_store must be symmetric");
3357 }
3358 #endif
3359
3360 return status_def;
3361 }
3362
3363 MergePrimitiveStores::Status MergePrimitiveStores::find_use_store_unidirectional(const StoreNode* def_store) const {
3364 assert(is_compatible_store(def_store), "precondition: must be compatible with _store");
3365
3366 for (DUIterator_Fast imax, i = def_store->fast_outs(imax); i < imax; i++) {
3367 StoreNode* use_store = def_store->fast_out(i)->isa_Store();
3368 if (is_compatible_store(use_store)) {
3369 return Status::make(use_store, cfg_status_for_pair(use_store, def_store));
3370 }
3371 }
3372
3373 return Status::make_failure();
3374 }
3375
3376 MergePrimitiveStores::Status MergePrimitiveStores::find_def_store_unidirectional(const StoreNode* use_store) const {
3377 assert(is_compatible_store(use_store), "precondition: must be compatible with _store");
3378
3379 StoreNode* def_store = use_store->in(MemNode::Memory)->isa_Store();
3380 if (!is_compatible_store(def_store)) {
3381 return Status::make_failure();
3382 }
3383
3384 return Status::make(def_store, cfg_status_for_pair(use_store, def_store));
3385 }
3386
3387 void MergePrimitiveStores::collect_merge_list(Node_List& merge_list) const {
3388 // The merged store can be at most 8 bytes.
3389 const uint merge_list_max_size = 8 / _store->memory_size();
3390 assert(merge_list_max_size >= 2 &&
3391 merge_list_max_size <= 8 &&
3392 is_power_of_2(merge_list_max_size),
3393 "must be 2, 4 or 8");
3394
3395 // Traverse up the chain of adjacent def stores.
3396 StoreNode* current = _store;
3397 merge_list.push(current);
3398 while (current != nullptr && merge_list.size() < merge_list_max_size) {
3399 Status status = find_adjacent_def_store(current);
3400 NOT_PRODUCT( if (is_trace_basic()) { tty->print("[TraceMergeStores] find def: "); status.print_on(tty); })
3401
3402 current = status.found_store();
3403 if (current != nullptr) {
3404 merge_list.push(current);
3405
3406 // We can have at most one RangeCheck.
3407 if (status.found_range_check()) {
3408 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found RangeCheck, stop traversal."); })
3409 break;
3410 }
3411 }
3412 }
3413
3414 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] found:"); merge_list.dump(); })
3415
3416 // Truncate the merge_list to a power of 2.
3417 const uint pow2size = round_down_power_of_2(merge_list.size());
3418 assert(pow2size >= 2, "must be merging at least 2 stores");
3419 while (merge_list.size() > pow2size) { merge_list.pop(); }
3420
3421 NOT_PRODUCT( if (is_trace_basic()) { tty->print_cr("[TraceMergeStores] truncated:"); merge_list.dump(); })
3422 }
3423
3424 // Merge the input values of the smaller stores to a single larger input value.
3425 Node* MergePrimitiveStores::make_merged_input_value(const Node_List& merge_list) {
3426 int new_memory_size = _store->memory_size() * merge_list.size();
3427 Node* first = merge_list.at(merge_list.size()-1);
3428 Node* merged_input_value = nullptr;
3429 if (_store->in(MemNode::ValueIn)->Opcode() == Op_ConI) {
3430 assert(_value_order == ValueOrder::Const, "must match");
3431 // Pattern: [ConI, ConI, ...] -> new constant
3432 jlong con = 0;
3433 jlong bits_per_store = _store->memory_size() * 8;
3434 jlong mask = (((jlong)1) << bits_per_store) - 1;
3435 for (uint i = 0; i < merge_list.size(); i++) {
3436 jlong con_i = merge_list.at(i)->in(MemNode::ValueIn)->get_int();
3437 #ifdef VM_LITTLE_ENDIAN
3438 con = con << bits_per_store;
3439 con = con | (mask & con_i);
3440 #else // VM_LITTLE_ENDIAN
3441 con_i = (mask & con_i) << (i * bits_per_store);
3442 con = con | con_i;
3443 #endif // VM_LITTLE_ENDIAN
3444 }
3445 merged_input_value = _phase->longcon(con);
3446 } else {
3447 assert(_value_order == ValueOrder::Platform || _value_order == ValueOrder::Reverse, "must match");
3448 // Pattern: [base >> 24, base >> 16, base >> 8, base] -> base
3449 // | |
3450 // _store first
3451 //
3452 Node* hi = _store->in(MemNode::ValueIn);
3453 Node* lo = first->in(MemNode::ValueIn);
3454 #ifndef VM_LITTLE_ENDIAN
3455 // `_store` and `first` are swapped in the diagram above
3456 swap(hi, lo);
3457 #endif // !VM_LITTLE_ENDIAN
3458 if (_value_order == ValueOrder::Reverse) {
3459 swap(hi, lo);
3460 }
3461 Node const* hi_base;
3462 jint hi_shift;
3463 merged_input_value = lo;
3464 bool is_true = is_con_RShift(hi, hi_base, hi_shift, _phase);
3465 assert(is_true, "must detect con RShift");
3466 if (merged_input_value != hi_base && merged_input_value->Opcode() == Op_ConvL2I) {
3467 // look through
3468 merged_input_value = merged_input_value->in(1);
3469 }
3470 if (merged_input_value != hi_base) {
3471 // merged_input_value is not the base
3472 return nullptr;
3473 }
3474 }
3475
3476 if (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size <= 4) {
3477 // Example:
3478 //
3479 // long base = ...;
3480 // a[0] = (byte)(base >> 0);
3481 // a[1] = (byte)(base >> 8);
3482 //
3483 merged_input_value = _phase->transform(new ConvL2INode(merged_input_value));
3484 }
3485
3486 assert((_phase->type(merged_input_value)->isa_int() != nullptr && new_memory_size <= 4) ||
3487 (_phase->type(merged_input_value)->isa_long() != nullptr && new_memory_size == 8),
3488 "merged_input_value is either int or long, and new_memory_size is small enough");
3489
3490 if (_value_order == ValueOrder::Reverse) {
3491 assert(_store->memory_size() == 1, "only implemented for bytes");
3492 if (new_memory_size == 8) {
3493 merged_input_value = _phase->transform(new ReverseBytesLNode(merged_input_value));
3494 } else if (new_memory_size == 4) {
3495 merged_input_value = _phase->transform(new ReverseBytesINode(merged_input_value));
3496 } else {
3497 assert(new_memory_size == 2, "sanity check");
3498 merged_input_value = _phase->transform(new ReverseBytesSNode(merged_input_value));
3499 }
3500 }
3501 return merged_input_value;
3502 }
3503
3504 // //
3505 // first_ctrl first_mem first_adr first_ctrl first_mem first_adr //
3506 // | | | | | | //
3507 // | | | | +---------------+ | //
3508 // | | | | | | | //
3509 // | | +---------+ | | +---------------+ //
3510 // | | | | | | | | //
3511 // +--------------+ | | v1 +------------------------------+ | | v1 //
3512 // | | | | | | | | | | | | //
3513 // RangeCheck first_store RangeCheck | | first_store //
3514 // | | | | | | | //
3515 // last_ctrl | +----> unc_trap last_ctrl | | +----> unc_trap //
3516 // | | ===> | | | //
3517 // +--------------+ | a2 v2 | | | //
3518 // | | | | | | | | //
3519 // | second_store | | | //
3520 // | | | | | [v1 v2 ... vn] //
3521 // ... ... | | | | //
3522 // | | | | | v //
3523 // +--------------+ | an vn +--------------+ | | merged_input_value //
3524 // | | | | | | | | //
3525 // last_store (= _store) merged_store //
3526 // //
3527 StoreNode* MergePrimitiveStores::make_merged_store(const Node_List& merge_list, Node* merged_input_value) {
3528 Node* first_store = merge_list.at(merge_list.size()-1);
3529 Node* last_ctrl = _store->in(MemNode::Control); // after (optional) RangeCheck
3530 Node* first_mem = first_store->in(MemNode::Memory);
3531 Node* first_adr = first_store->in(MemNode::Address);
3532
3533 const TypePtr* new_adr_type = _store->adr_type();
3534
3535 int new_memory_size = _store->memory_size() * merge_list.size();
3536 BasicType bt = T_ILLEGAL;
3537 switch (new_memory_size) {
3538 case 2: bt = T_SHORT; break;
3539 case 4: bt = T_INT; break;
3540 case 8: bt = T_LONG; break;
3541 }
3542
3543 StoreNode* merged_store = StoreNode::make(*_phase, last_ctrl, first_mem, first_adr,
3544 new_adr_type, merged_input_value, bt, MemNode::unordered);
3545
3546 // Marking the store mismatched is sufficient to prevent reordering, since array stores
3547 // are all on the same slice. Hence, we need no barriers.
3548 merged_store->set_mismatched_access();
3549
3550 // Constants above may now also be be packed -> put candidate on worklist
3551 _phase->is_IterGVN()->_worklist.push(first_mem);
3552
3553 return merged_store;
3554 }
3555
3556 #ifndef PRODUCT
3557 void MergePrimitiveStores::trace(const Node_List& merge_list, const Node* merged_input_value, const StoreNode* merged_store) const {
3558 stringStream ss;
3559 ss.print_cr("[TraceMergeStores]: Replace");
3560 for (int i = (int)merge_list.size() - 1; i >= 0; i--) {
3561 merge_list.at(i)->dump("\n", false, &ss);
3562 }
3563 ss.print_cr("[TraceMergeStores]: with");
3564 merged_input_value->dump("\n", false, &ss);
3565 merged_store->dump("\n", false, &ss);
3566 tty->print("%s", ss.as_string());
3567 }
3568 #endif
3569
3570 //------------------------------Ideal------------------------------------------
3571 // Change back-to-back Store(, p, x) -> Store(m, p, y) to Store(m, p, x).
3572 // When a store immediately follows a relevant allocation/initialization,
3573 // try to capture it into the initialization, or hoist it above.
3574 Node *StoreNode::Ideal(PhaseGVN *phase, bool can_reshape) {
3575 Node* p = MemNode::Ideal_common(phase, can_reshape);
3576 if (p) return (p == NodeSentinel) ? nullptr : p;
3577
3578 Node* mem = in(MemNode::Memory);
3579 Node* address = in(MemNode::Address);
3580 Node* value = in(MemNode::ValueIn);
3581 // Back-to-back stores to same address? Fold em up. Generally
3582 // unsafe if I have intervening uses...
3583 if (phase->C->get_adr_type(phase->C->get_alias_index(adr_type())) != TypeAryPtr::INLINES) {
3584 Node* st = mem;
3585 // If Store 'st' has more than one use, we cannot fold 'st' away.
3586 // For example, 'st' might be the final state at a conditional
3587 // return. Or, 'st' might be used by some node which is live at
3588 // the same time 'st' is live, which might be unschedulable. So,
3589 // require exactly ONE user until such time as we clone 'mem' for
3590 // each of 'mem's uses (thus making the exactly-1-user-rule hold
3591 // true).
3592 while (st->is_Store() && st->outcnt() == 1) {
3593 // Looking at a dead closed cycle of memory?
3594 assert(st != st->in(MemNode::Memory), "dead loop in StoreNode::Ideal");
3595 assert(Opcode() == st->Opcode() ||
3596 st->Opcode() == Op_StoreVector ||
3597 Opcode() == Op_StoreVector ||
3598 st->Opcode() == Op_StoreVectorScatter ||
3599 Opcode() == Op_StoreVectorScatter ||
3600 phase->C->get_alias_index(adr_type()) == Compile::AliasIdxRaw ||
3601 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreI) || // expanded ClearArrayNode
3602 (Opcode() == Op_StoreI && st->Opcode() == Op_StoreL) || // initialization by arraycopy
3603 (Opcode() == Op_StoreL && st->Opcode() == Op_StoreN) ||
3604 (st->adr_type()->isa_aryptr() && st->adr_type()->is_aryptr()->is_flat()) || // TODO 8343835
3605 (is_mismatched_access() || st->as_Store()->is_mismatched_access()),
3606 "no mismatched stores, except on raw memory: %s %s", NodeClassNames[Opcode()], NodeClassNames[st->Opcode()]);
3607
3608 if (st->in(MemNode::Address)->eqv_uncast(address) &&
3609 st->as_Store()->memory_size() <= this->memory_size()) {
3610 Node* use = st->raw_out(0);
3611 if (phase->is_IterGVN()) {
3612 phase->is_IterGVN()->rehash_node_delayed(use);
3613 }
3614 // It's OK to do this in the parser, since DU info is always accurate,
3615 // and the parser always refers to nodes via SafePointNode maps.
3616 use->set_req_X(MemNode::Memory, st->in(MemNode::Memory), phase);
3617 return this;
3618 }
3619 st = st->in(MemNode::Memory);
3620 }
3621 }
3622
3623
3624 // Capture an unaliased, unconditional, simple store into an initializer.
3625 // Or, if it is independent of the allocation, hoist it above the allocation.
3626 if (ReduceFieldZeroing && /*can_reshape &&*/
3627 mem->is_Proj() && mem->in(0)->is_Initialize()) {
3628 InitializeNode* init = mem->in(0)->as_Initialize();
3629 intptr_t offset = init->can_capture_store(this, phase, can_reshape);
3630 if (offset > 0) {
3631 Node* moved = init->capture_store(this, offset, phase, can_reshape);
3632 // If the InitializeNode captured me, it made a raw copy of me,
3633 // and I need to disappear.
3634 if (moved != nullptr) {
3635 // %%% hack to ensure that Ideal returns a new node:
3636 mem = MergeMemNode::make(mem);
3637 return mem; // fold me away
3638 }
3639 }
3640 }
3641
3642 // Fold reinterpret cast into memory operation:
3643 // StoreX mem (MoveY2X v) => StoreY mem v
3644 if (value->is_Move()) {
3645 const Type* vt = value->in(1)->bottom_type();
3646 if (has_reinterpret_variant(vt)) {
3647 if (phase->C->post_loop_opts_phase()) {
3648 return convert_to_reinterpret_store(*phase, value->in(1), vt);
3649 } else {
3650 phase->C->record_for_post_loop_opts_igvn(this); // attempt the transformation once loop opts are over
3651 }
3652 }
3653 }
3654
3655 if (MergeStores && UseUnalignedAccesses) {
3656 if (phase->C->merge_stores_phase()) {
3657 MergePrimitiveStores merge(phase, this);
3658 Node* progress = merge.run();
3659 if (progress != nullptr) { return progress; }
3660 } else {
3661 // We need to wait with merging stores until RangeCheck smearing has removed the RangeChecks during
3662 // the post loops IGVN phase. If we do it earlier, then there may still be some RangeChecks between
3663 // the stores, and we merge the wrong sequence of stores.
3664 // Example:
3665 // StoreI RangeCheck StoreI StoreI RangeCheck StoreI
3666 // Apply MergeStores:
3667 // StoreI RangeCheck [ StoreL ] RangeCheck StoreI
3668 // Remove more RangeChecks:
3669 // StoreI [ StoreL ] StoreI
3670 // But now it would have been better to do this instead:
3671 // [ StoreL ] [ StoreL ]
3672 phase->C->record_for_merge_stores_igvn(this);
3673 }
3674 }
3675
3676 return nullptr; // No further progress
3677 }
3678
3679 //------------------------------Value-----------------------------------------
3680 const Type* StoreNode::Value(PhaseGVN* phase) const {
3681 // Either input is TOP ==> the result is TOP
3682 const Type *t1 = phase->type( in(MemNode::Memory) );
3683 if( t1 == Type::TOP ) return Type::TOP;
3684 const Type *t2 = phase->type( in(MemNode::Address) );
3685 if( t2 == Type::TOP ) return Type::TOP;
3686 const Type *t3 = phase->type( in(MemNode::ValueIn) );
3687 if( t3 == Type::TOP ) return Type::TOP;
3688 return Type::MEMORY;
3689 }
3690
3691 //------------------------------Identity---------------------------------------
3692 // Remove redundant stores:
3693 // Store(m, p, Load(m, p)) changes to m.
3694 // Store(, p, x) -> Store(m, p, x) changes to Store(m, p, x).
3695 Node* StoreNode::Identity(PhaseGVN* phase) {
3696 Node* mem = in(MemNode::Memory);
3697 Node* adr = in(MemNode::Address);
3698 Node* val = in(MemNode::ValueIn);
3699
3700 Node* result = this;
3701
3702 // Load then Store? Then the Store is useless
3703 if (val->is_Load() &&
3704 val->in(MemNode::Address)->eqv_uncast(adr) &&
3705 val->in(MemNode::Memory )->eqv_uncast(mem) &&
3706 val->as_Load()->store_Opcode() == Opcode()) {
3707 // Ensure vector type is the same
3708 if (!is_StoreVector() || (mem->is_LoadVector() && as_StoreVector()->vect_type() == mem->as_LoadVector()->vect_type())) {
3709 result = mem;
3710 }
3711 }
3712
3713 // Two stores in a row of the same value?
3714 if (result == this &&
3715 mem->is_Store() &&
3716 mem->in(MemNode::Address)->eqv_uncast(adr) &&
3717 mem->in(MemNode::ValueIn)->eqv_uncast(val) &&
3718 mem->Opcode() == Opcode()) {
3719 if (!is_StoreVector()) {
3720 result = mem;
3721 } else {
3722 const StoreVectorNode* store_vector = as_StoreVector();
3723 const StoreVectorNode* mem_vector = mem->as_StoreVector();
3724 const Node* store_indices = store_vector->indices();
3725 const Node* mem_indices = mem_vector->indices();
3726 const Node* store_mask = store_vector->mask();
3727 const Node* mem_mask = mem_vector->mask();
3728 // Ensure types, indices, and masks match
3729 if (store_vector->vect_type() == mem_vector->vect_type() &&
3730 ((store_indices == nullptr) == (mem_indices == nullptr) &&
3731 (store_indices == nullptr || store_indices->eqv_uncast(mem_indices))) &&
3732 ((store_mask == nullptr) == (mem_mask == nullptr) &&
3733 (store_mask == nullptr || store_mask->eqv_uncast(mem_mask)))) {
3734 result = mem;
3735 }
3736 }
3737 }
3738
3739 // Store of zero anywhere into a freshly-allocated object?
3740 // Then the store is useless.
3741 // (It must already have been captured by the InitializeNode.)
3742 if (result == this && ReduceFieldZeroing) {
3743 // a newly allocated object is already all-zeroes everywhere
3744 if (mem->is_Proj() && mem->in(0)->is_Allocate() &&
3745 (phase->type(val)->is_zero_type() || mem->in(0)->in(AllocateNode::InitValue) == val)) {
3746 result = mem;
3747 }
3748
3749 if (result == this && phase->type(val)->is_zero_type()) {
3750 // the store may also apply to zero-bits in an earlier object
3751 Node* prev_mem = find_previous_store(phase);
3752 // Steps (a), (b): Walk past independent stores to find an exact match.
3753 if (prev_mem != nullptr) {
3754 Node* prev_val = can_see_stored_value(prev_mem, phase);
3755 if (prev_val != nullptr && prev_val == val) {
3756 // prev_val and val might differ by a cast; it would be good
3757 // to keep the more informative of the two.
3758 result = mem;
3759 }
3760 }
3761 }
3762 }
3763
3764 PhaseIterGVN* igvn = phase->is_IterGVN();
3765 if (result != this && igvn != nullptr) {
3766 MemBarNode* trailing = trailing_membar();
3767 if (trailing != nullptr) {
3768 #ifdef ASSERT
3769 const TypeOopPtr* t_oop = phase->type(in(Address))->isa_oopptr();
3770 assert(t_oop == nullptr || t_oop->is_known_instance_field(), "only for non escaping objects");
3771 #endif
3772 trailing->remove(igvn);
3773 }
3774 }
3775
3776 return result;
3777 }
3778
3779 //------------------------------match_edge-------------------------------------
3780 // Do we Match on this edge index or not? Match only memory & value
3781 uint StoreNode::match_edge(uint idx) const {
3782 return idx == MemNode::Address || idx == MemNode::ValueIn;
3783 }
3784
3785 //------------------------------cmp--------------------------------------------
3786 // Do not common stores up together. They generally have to be split
3787 // back up anyways, so do not bother.
3788 bool StoreNode::cmp( const Node &n ) const {
3789 return (&n == this); // Always fail except on self
3790 }
3791
3792 //------------------------------Ideal_masked_input-----------------------------
3793 // Check for a useless mask before a partial-word store
3794 // (StoreB ... (AndI valIn conIa) )
3795 // If (conIa & mask == mask) this simplifies to
3796 // (StoreB ... (valIn) )
3797 Node *StoreNode::Ideal_masked_input(PhaseGVN *phase, uint mask) {
3798 Node *val = in(MemNode::ValueIn);
3799 if( val->Opcode() == Op_AndI ) {
3800 const TypeInt *t = phase->type( val->in(2) )->isa_int();
3801 if( t && t->is_con() && (t->get_con() & mask) == mask ) {
3802 set_req_X(MemNode::ValueIn, val->in(1), phase);
3803 return this;
3804 }
3805 }
3806 return nullptr;
3807 }
3808
3809
3810 //------------------------------Ideal_sign_extended_input----------------------
3811 // Check for useless sign-extension before a partial-word store
3812 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3813 // If (conIL == conIR && conIR <= num_rejected_bits) this simplifies to
3814 // (StoreB ... (v))
3815 // If (conIL > conIR) under some conditions, it can be simplified into
3816 // (StoreB ... (LShiftI _ v (conIL - conIR)))
3817 // This case happens when the value of the store was itself a left shift, that
3818 // gets merged into the inner left shift of the sign-extension. For instance,
3819 // if we have
3820 // array_of_shorts[0] = (short)(v << 2)
3821 // We get a structure such as:
3822 // (StoreB ... (RShiftI _ (LShiftI _ (LShiftI _ v 2) 16) 16))
3823 // that is simplified into
3824 // (StoreB ... (RShiftI _ (LShiftI _ v 18) 16)).
3825 // It is thus useful to handle cases where conIL > conIR. But this simplification
3826 // does not always hold. Let's see in which cases it's valid.
3827 //
3828 // Let's assume we have the following 32 bits integer v:
3829 // +----------------------------------+
3830 // | v[0..31] |
3831 // +----------------------------------+
3832 // 31 0
3833 // that will be stuffed in 8 bits byte after a shift left and a shift right of
3834 // potentially different magnitudes.
3835 // We denote num_rejected_bits the number of bits of the discarded part. In this
3836 // case, num_rejected_bits == 24.
3837 //
3838 // Statement (proved further below in case analysis):
3839 // Given:
3840 // - 0 <= conIL < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3841 // - 0 <= conIR < BitsPerJavaInteger (no wrap in shift, enforced by maskShiftAmount)
3842 // - conIL >= conIR
3843 // - num_rejected_bits >= conIR
3844 // Then this form:
3845 // (RShiftI _ (LShiftI _ v conIL) conIR)
3846 // can be replaced with this form:
3847 // (LShiftI _ v (conIL-conIR))
3848 //
3849 // Note: We only have to show that the non-rejected lowest bits (8 bits for byte)
3850 // have to be correct, as the higher bits are rejected / truncated by the store.
3851 //
3852 // The hypotheses
3853 // 0 <= conIL < BitsPerJavaInteger
3854 // 0 <= conIR < BitsPerJavaInteger
3855 // are ensured by maskShiftAmount (called from ::Ideal of shift nodes). Indeed,
3856 // (v << 31) << 2 must be simplified into 0, not into v << 33 (which is equivalent
3857 // to v << 1).
3858 //
3859 //
3860 // If you don't like case analysis, jump after the conclusion.
3861 // ### Case 1 : conIL == conIR
3862 // ###### Case 1.1: conIL == conIR == num_rejected_bits
3863 // If we do the shift left then right by 24 bits, we get:
3864 // after: v << 24
3865 // +---------+------------------------+
3866 // | v[0..7] | 0 |
3867 // +---------+------------------------+
3868 // 31 24 23 0
3869 // after: (v << 24) >> 24
3870 // +------------------------+---------+
3871 // | sign bit | v[0..7] |
3872 // +------------------------+---------+
3873 // 31 8 7 0
3874 // The non-rejected bits (bits kept by the store, that is the 8 lower bits of the
3875 // result) are the same before and after, so, indeed, simplifying is correct.
3876
3877 // ###### Case 1.2: conIL == conIR < num_rejected_bits
3878 // If we do the shift left then right by 22 bits, we get:
3879 // after: v << 22
3880 // +---------+------------------------+
3881 // | v[0..9] | 0 |
3882 // +---------+------------------------+
3883 // 31 22 21 0
3884 // after: (v << 22) >> 22
3885 // +------------------------+---------+
3886 // | sign bit | v[0..9] |
3887 // +------------------------+---------+
3888 // 31 10 9 0
3889 // The non-rejected bits are the 8 lower bits of v. The bits 8 and 9 of v are still
3890 // present in (v << 22) >> 22 but will be dropped by the store. The simplification is
3891 // still correct.
3892
3893 // ###### But! Case 1.3: conIL == conIR > num_rejected_bits
3894 // If we do the shift left then right by 26 bits, we get:
3895 // after: v << 26
3896 // +---------+------------------------+
3897 // | v[0..5] | 0 |
3898 // +---------+------------------------+
3899 // 31 26 25 0
3900 // after: (v << 26) >> 26
3901 // +------------------------+---------+
3902 // | sign bit | v[0..5] |
3903 // +------------------------+---------+
3904 // 31 6 5 0
3905 // The non-rejected bits are made of
3906 // - 0-5 => the bits 0 to 5 of v
3907 // - 6-7 => the sign bit of v[0..5] (that is v[5])
3908 // Simplifying this as v is not correct.
3909 // The condition conIR <= num_rejected_bits is indeed necessary in Case 1
3910 //
3911 // ### Case 2: conIL > conIR
3912 // ###### Case 2.1: num_rejected_bits == conIR
3913 // We take conIL == 26 for this example.
3914 // after: v << 26
3915 // +---------+------------------------+
3916 // | v[0..5] | 0 |
3917 // +---------+------------------------+
3918 // 31 26 25 0
3919 // after: (v << 26) >> 24
3920 // +------------------+---------+-----+
3921 // | sign bit | v[0..5] | 0 |
3922 // +------------------+---------+-----+
3923 // 31 8 7 2 1 0
3924 // The non-rejected bits are the 8 lower ones of (v << conIL - conIR).
3925 // The bits 6 and 7 of v have been thrown away after the shift left.
3926 // The simplification is still correct.
3927 //
3928 // ###### Case 2.2: num_rejected_bits > conIR.
3929 // Let's say conIL == 26 and conIR == 22.
3930 // after: v << 26
3931 // +---------+------------------------+
3932 // | v[0..5] | 0 |
3933 // +---------+------------------------+
3934 // 31 26 25 0
3935 // after: (v << 26) >> 22
3936 // +------------------+---------+-----+
3937 // | sign bit | v[0..5] | 0 |
3938 // +------------------+---------+-----+
3939 // 31 10 9 4 3 0
3940 // The bits non-rejected by the store are exactly the 8 lower ones of (v << (conIL - conIR)):
3941 // - 0-3 => 0
3942 // - 4-7 => bits 0 to 3 of v
3943 // The simplification is still correct.
3944 // The bits 4 and 5 of v are still present in (v << (conIL - conIR)) but they don't
3945 // matter as they are not in the 8 lower bits: they will be cut out by the store.
3946 //
3947 // ###### But! Case 2.3: num_rejected_bits < conIR.
3948 // Let's see that this case is not as easy to simplify.
3949 // Let's say conIL == 28 and conIR == 26.
3950 // after: v << 28
3951 // +---------+------------------------+
3952 // | v[0..3] | 0 |
3953 // +---------+------------------------+
3954 // 31 28 27 0
3955 // after: (v << 28) >> 26
3956 // +------------------+---------+-----+
3957 // | sign bit | v[0..3] | 0 |
3958 // +------------------+---------+-----+
3959 // 31 6 5 2 1 0
3960 // The non-rejected bits are made of
3961 // - 0-1 => 0
3962 // - 2-5 => the bits 0 to 3 of v
3963 // - 6-7 => the sign bit of v[0..3] (that is v[3])
3964 // Simplifying this as (v << 2) is not correct.
3965 // The condition conIR <= num_rejected_bits is indeed necessary in Case 2.
3966 //
3967 // ### Conclusion:
3968 // Our hypotheses are indeed sufficient:
3969 // - 0 <= conIL < BitsPerJavaInteger
3970 // - 0 <= conIR < BitsPerJavaInteger
3971 // - conIL >= conIR
3972 // - num_rejected_bits >= conIR
3973 //
3974 // ### A rationale without case analysis:
3975 // After the shift left, conIL upper bits of v are discarded and conIL lower bit
3976 // zeroes are added. After the shift right, conIR lower bits of the previous result
3977 // are discarded. If conIL >= conIR, we discard only the zeroes we made up during
3978 // the shift left, but if conIL < conIR, then we discard also lower bits of v. But
3979 // the point of the simplification is to get an expression of the form
3980 // (v << (conIL - conIR)). This expression discard only higher bits of v, thus the
3981 // simplification is not correct if conIL < conIR.
3982 //
3983 // Moreover, after the shift right, the higher bit of (v << conIL) is repeated on the
3984 // conIR higher bits of ((v << conIL) >> conIR), it's the sign-extension. If
3985 // conIR > num_rejected_bits, then at least one artificial copy of this sign bit will
3986 // be in the window of the store. Thus ((v << conIL) >> conIR) is not equivalent to
3987 // (v << (conIL-conIR)) if conIR > num_rejected_bits.
3988 //
3989 // We do not treat the case conIL < conIR here since the point of this function is
3990 // to skip sign-extensions (that is conIL == conIR == num_rejected_bits). The need
3991 // of treating conIL > conIR comes from the cases where the sign-extended value is
3992 // also left-shift expression. Computing the sign-extension of a right-shift expression
3993 // doesn't yield a situation such as
3994 // (StoreB ... (RShiftI _ (LShiftI _ v conIL) conIR))
3995 // where conIL < conIR.
3996 Node* StoreNode::Ideal_sign_extended_input(PhaseGVN* phase, int num_rejected_bits) {
3997 Node* shr = in(MemNode::ValueIn);
3998 if (shr->Opcode() == Op_RShiftI) {
3999 const TypeInt* conIR = phase->type(shr->in(2))->isa_int();
4000 if (conIR != nullptr && conIR->is_con() && conIR->get_con() >= 0 && conIR->get_con() < BitsPerJavaInteger && conIR->get_con() <= num_rejected_bits) {
4001 Node* shl = shr->in(1);
4002 if (shl->Opcode() == Op_LShiftI) {
4003 const TypeInt* conIL = phase->type(shl->in(2))->isa_int();
4004 if (conIL != nullptr && conIL->is_con() && conIL->get_con() >= 0 && conIL->get_con() < BitsPerJavaInteger) {
4005 if (conIL->get_con() == conIR->get_con()) {
4006 set_req_X(MemNode::ValueIn, shl->in(1), phase);
4007 return this;
4008 }
4009 if (conIL->get_con() > conIR->get_con()) {
4010 Node* new_shl = phase->transform(new LShiftINode(shl->in(1), phase->intcon(conIL->get_con() - conIR->get_con())));
4011 set_req_X(MemNode::ValueIn, new_shl, phase);
4012 return this;
4013 }
4014 }
4015 }
4016 }
4017 }
4018 return nullptr;
4019 }
4020
4021 //------------------------------value_never_loaded-----------------------------------
4022 // Determine whether there are any possible loads of the value stored.
4023 // For simplicity, we actually check if there are any loads from the
4024 // address stored to, not just for loads of the value stored by this node.
4025 //
4026 bool StoreNode::value_never_loaded(PhaseValues* phase) const {
4027 Node *adr = in(Address);
4028 const TypeOopPtr *adr_oop = phase->type(adr)->isa_oopptr();
4029 if (adr_oop == nullptr)
4030 return false;
4031 if (!adr_oop->is_known_instance_field())
4032 return false; // if not a distinct instance, there may be aliases of the address
4033 for (DUIterator_Fast imax, i = adr->fast_outs(imax); i < imax; i++) {
4034 Node *use = adr->fast_out(i);
4035 if (use->is_Load() || use->is_LoadStore()) {
4036 return false;
4037 }
4038 }
4039 return true;
4040 }
4041
4042 MemBarNode* StoreNode::trailing_membar() const {
4043 if (is_release()) {
4044 MemBarNode* trailing_mb = nullptr;
4045 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4046 Node* u = fast_out(i);
4047 if (u->is_MemBar()) {
4048 if (u->as_MemBar()->trailing_store()) {
4049 assert(u->Opcode() == Op_MemBarVolatile, "");
4050 assert(trailing_mb == nullptr, "only one");
4051 trailing_mb = u->as_MemBar();
4052 #ifdef ASSERT
4053 Node* leading = u->as_MemBar()->leading_membar();
4054 assert(leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4055 assert(leading->as_MemBar()->leading_store(), "incorrect membar pair");
4056 assert(leading->as_MemBar()->trailing_membar() == u, "incorrect membar pair");
4057 #endif
4058 } else {
4059 assert(u->as_MemBar()->standalone(), "");
4060 }
4061 }
4062 }
4063 return trailing_mb;
4064 }
4065 return nullptr;
4066 }
4067
4068
4069 //=============================================================================
4070 //------------------------------Ideal------------------------------------------
4071 // If the store is from an AND mask that leaves the low bits untouched, then
4072 // we can skip the AND operation. If the store is from a sign-extension
4073 // (a left shift, then right shift) we can skip both.
4074 Node *StoreBNode::Ideal(PhaseGVN *phase, bool can_reshape){
4075 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFF);
4076 if( progress != nullptr ) return progress;
4077
4078 progress = StoreNode::Ideal_sign_extended_input(phase, 24);
4079 if( progress != nullptr ) return progress;
4080
4081 // Finally check the default case
4082 return StoreNode::Ideal(phase, can_reshape);
4083 }
4084
4085 //=============================================================================
4086 //------------------------------Ideal------------------------------------------
4087 // If the store is from an AND mask that leaves the low bits untouched, then
4088 // we can skip the AND operation
4089 Node *StoreCNode::Ideal(PhaseGVN *phase, bool can_reshape){
4090 Node *progress = StoreNode::Ideal_masked_input(phase, 0xFFFF);
4091 if( progress != nullptr ) return progress;
4092
4093 progress = StoreNode::Ideal_sign_extended_input(phase, 16);
4094 if( progress != nullptr ) return progress;
4095
4096 // Finally check the default case
4097 return StoreNode::Ideal(phase, can_reshape);
4098 }
4099
4100 //=============================================================================
4101 //----------------------------------SCMemProjNode------------------------------
4102 const Type* SCMemProjNode::Value(PhaseGVN* phase) const
4103 {
4104 if (in(0) == nullptr || phase->type(in(0)) == Type::TOP) {
4105 return Type::TOP;
4106 }
4107 return bottom_type();
4108 }
4109
4110 //=============================================================================
4111 //----------------------------------LoadStoreNode------------------------------
4112 LoadStoreNode::LoadStoreNode( Node *c, Node *mem, Node *adr, Node *val, const TypePtr* at, const Type* rt, uint required )
4113 : Node(required),
4114 _type(rt),
4115 _adr_type(at),
4116 _barrier_data(0)
4117 {
4118 init_req(MemNode::Control, c );
4119 init_req(MemNode::Memory , mem);
4120 init_req(MemNode::Address, adr);
4121 init_req(MemNode::ValueIn, val);
4122 init_class_id(Class_LoadStore);
4123 }
4124
4125 //------------------------------Value-----------------------------------------
4126 const Type* LoadStoreNode::Value(PhaseGVN* phase) const {
4127 // Either input is TOP ==> the result is TOP
4128 if (!in(MemNode::Control) || phase->type(in(MemNode::Control)) == Type::TOP) {
4129 return Type::TOP;
4130 }
4131 const Type* t = phase->type(in(MemNode::Memory));
4132 if (t == Type::TOP) {
4133 return Type::TOP;
4134 }
4135 t = phase->type(in(MemNode::Address));
4136 if (t == Type::TOP) {
4137 return Type::TOP;
4138 }
4139 t = phase->type(in(MemNode::ValueIn));
4140 if (t == Type::TOP) {
4141 return Type::TOP;
4142 }
4143 return bottom_type();
4144 }
4145
4146 uint LoadStoreNode::ideal_reg() const {
4147 return _type->ideal_reg();
4148 }
4149
4150 // This method conservatively checks if the result of a LoadStoreNode is
4151 // used, that is, if it returns true, then it is definitely the case that
4152 // the result of the node is not needed.
4153 // For example, GetAndAdd can be matched into a lock_add instead of a
4154 // lock_xadd if the result of LoadStoreNode::result_not_used() is true
4155 bool LoadStoreNode::result_not_used() const {
4156 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4157 Node *x = fast_out(i);
4158 if (x->Opcode() == Op_SCMemProj) {
4159 continue;
4160 }
4161 if (x->bottom_type() == TypeTuple::MEMBAR &&
4162 !x->is_Call() &&
4163 x->Opcode() != Op_Blackhole) {
4164 continue;
4165 }
4166 return false;
4167 }
4168 return true;
4169 }
4170
4171 MemBarNode* LoadStoreNode::trailing_membar() const {
4172 MemBarNode* trailing = nullptr;
4173 for (DUIterator_Fast imax, i = fast_outs(imax); i < imax; i++) {
4174 Node* u = fast_out(i);
4175 if (u->is_MemBar()) {
4176 if (u->as_MemBar()->trailing_load_store()) {
4177 assert(u->Opcode() == Op_MemBarAcquire, "");
4178 assert(trailing == nullptr, "only one");
4179 trailing = u->as_MemBar();
4180 #ifdef ASSERT
4181 Node* leading = trailing->leading_membar();
4182 assert(support_IRIW_for_not_multiple_copy_atomic_cpu || leading->Opcode() == Op_MemBarRelease, "incorrect membar");
4183 assert(leading->as_MemBar()->leading_load_store(), "incorrect membar pair");
4184 assert(leading->as_MemBar()->trailing_membar() == trailing, "incorrect membar pair");
4185 #endif
4186 } else {
4187 assert(u->as_MemBar()->standalone(), "wrong barrier kind");
4188 }
4189 }
4190 }
4191
4192 return trailing;
4193 }
4194
4195 uint LoadStoreNode::size_of() const { return sizeof(*this); }
4196
4197 //=============================================================================
4198 //----------------------------------LoadStoreConditionalNode--------------------
4199 LoadStoreConditionalNode::LoadStoreConditionalNode( Node *c, Node *mem, Node *adr, Node *val, Node *ex ) : LoadStoreNode(c, mem, adr, val, nullptr, TypeInt::BOOL, 5) {
4200 init_req(ExpectedIn, ex );
4201 }
4202
4203 const Type* LoadStoreConditionalNode::Value(PhaseGVN* phase) const {
4204 // Either input is TOP ==> the result is TOP
4205 const Type* t = phase->type(in(ExpectedIn));
4206 if (t == Type::TOP) {
4207 return Type::TOP;
4208 }
4209 return LoadStoreNode::Value(phase);
4210 }
4211
4212 //=============================================================================
4213 //-------------------------------adr_type--------------------------------------
4214 const TypePtr* ClearArrayNode::adr_type() const {
4215 Node *adr = in(3);
4216 if (adr == nullptr) return nullptr; // node is dead
4217 return MemNode::calculate_adr_type(adr->bottom_type());
4218 }
4219
4220 //------------------------------match_edge-------------------------------------
4221 // Do we Match on this edge index or not? Do not match memory
4222 uint ClearArrayNode::match_edge(uint idx) const {
4223 return idx > 1;
4224 }
4225
4226 //------------------------------Identity---------------------------------------
4227 // Clearing a zero length array does nothing
4228 Node* ClearArrayNode::Identity(PhaseGVN* phase) {
4229 return phase->type(in(2))->higher_equal(TypeX::ZERO) ? in(1) : this;
4230 }
4231
4232 //------------------------------Idealize---------------------------------------
4233 // Clearing a short array is faster with stores
4234 Node *ClearArrayNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4235 // Already know this is a large node, do not try to ideal it
4236 if (_is_large) return nullptr;
4237
4238 const int unit = BytesPerLong;
4239 const TypeX* t = phase->type(in(2))->isa_intptr_t();
4240 if (!t) return nullptr;
4241 if (!t->is_con()) return nullptr;
4242 intptr_t raw_count = t->get_con();
4243 intptr_t size = raw_count;
4244 if (!Matcher::init_array_count_is_in_bytes) size *= unit;
4245 // Clearing nothing uses the Identity call.
4246 // Negative clears are possible on dead ClearArrays
4247 // (see jck test stmt114.stmt11402.val).
4248 if (size <= 0 || size % unit != 0) return nullptr;
4249 intptr_t count = size / unit;
4250 // Length too long; communicate this to matchers and assemblers.
4251 // Assemblers are responsible to produce fast hardware clears for it.
4252 if (size > InitArrayShortSize) {
4253 return new ClearArrayNode(in(0), in(1), in(2), in(3), in(4), true);
4254 } else if (size > 2 && Matcher::match_rule_supported_vector(Op_ClearArray, 4, T_LONG)) {
4255 return nullptr;
4256 }
4257 if (!IdealizeClearArrayNode) return nullptr;
4258 Node *mem = in(1);
4259 if( phase->type(mem)==Type::TOP ) return nullptr;
4260 Node *adr = in(3);
4261 const Type* at = phase->type(adr);
4262 if( at==Type::TOP ) return nullptr;
4263 const TypePtr* atp = at->isa_ptr();
4264 // adjust atp to be the correct array element address type
4265 if (atp == nullptr) atp = TypePtr::BOTTOM;
4266 else atp = atp->add_offset(Type::OffsetBot);
4267 // Get base for derived pointer purposes
4268 if( adr->Opcode() != Op_AddP ) Unimplemented();
4269 Node *base = adr->in(1);
4270
4271 Node *val = in(4);
4272 Node *off = phase->MakeConX(BytesPerLong);
4273 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
4274 count--;
4275 while( count-- ) {
4276 mem = phase->transform(mem);
4277 adr = phase->transform(new AddPNode(base,adr,off));
4278 mem = new StoreLNode(in(0), mem, adr, atp, val, MemNode::unordered, false);
4279 }
4280 return mem;
4281 }
4282
4283 //----------------------------step_through----------------------------------
4284 // Return allocation input memory edge if it is different instance
4285 // or itself if it is the one we are looking for.
4286 bool ClearArrayNode::step_through(Node** np, uint instance_id, PhaseValues* phase) {
4287 Node* n = *np;
4288 assert(n->is_ClearArray(), "sanity");
4289 intptr_t offset;
4290 AllocateNode* alloc = AllocateNode::Ideal_allocation(n->in(3), phase, offset);
4291 // This method is called only before Allocate nodes are expanded
4292 // during macro nodes expansion. Before that ClearArray nodes are
4293 // only generated in PhaseMacroExpand::generate_arraycopy() (before
4294 // Allocate nodes are expanded) which follows allocations.
4295 assert(alloc != nullptr, "should have allocation");
4296 if (alloc->_idx == instance_id) {
4297 // Can not bypass initialization of the instance we are looking for.
4298 return false;
4299 }
4300 // Otherwise skip it.
4301 InitializeNode* init = alloc->initialization();
4302 if (init != nullptr)
4303 *np = init->in(TypeFunc::Memory);
4304 else
4305 *np = alloc->in(TypeFunc::Memory);
4306 return true;
4307 }
4308
4309 //----------------------------clear_memory-------------------------------------
4310 // Generate code to initialize object storage to zero.
4311 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4312 Node* val,
4313 Node* raw_val,
4314 intptr_t start_offset,
4315 Node* end_offset,
4316 PhaseGVN* phase) {
4317 intptr_t offset = start_offset;
4318
4319 int unit = BytesPerLong;
4320 if ((offset % unit) != 0) {
4321 Node* adr = new AddPNode(dest, dest, phase->MakeConX(offset));
4322 adr = phase->transform(adr);
4323 const TypePtr* atp = TypeRawPtr::BOTTOM;
4324 if (val != nullptr) {
4325 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
4326 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
4327 } else {
4328 assert(raw_val == nullptr, "val may not be null");
4329 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4330 }
4331 mem = phase->transform(mem);
4332 offset += BytesPerInt;
4333 }
4334 assert((offset % unit) == 0, "");
4335
4336 // Initialize the remaining stuff, if any, with a ClearArray.
4337 return clear_memory(ctl, mem, dest, raw_val, phase->MakeConX(offset), end_offset, phase);
4338 }
4339
4340 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4341 Node* raw_val,
4342 Node* start_offset,
4343 Node* end_offset,
4344 PhaseGVN* phase) {
4345 if (start_offset == end_offset) {
4346 // nothing to do
4347 return mem;
4348 }
4349
4350 int unit = BytesPerLong;
4351 Node* zbase = start_offset;
4352 Node* zend = end_offset;
4353
4354 // Scale to the unit required by the CPU:
4355 if (!Matcher::init_array_count_is_in_bytes) {
4356 Node* shift = phase->intcon(exact_log2(unit));
4357 zbase = phase->transform(new URShiftXNode(zbase, shift) );
4358 zend = phase->transform(new URShiftXNode(zend, shift) );
4359 }
4360
4361 // Bulk clear double-words
4362 Node* zsize = phase->transform(new SubXNode(zend, zbase) );
4363 Node* adr = phase->transform(new AddPNode(dest, dest, start_offset) );
4364 if (raw_val == nullptr) {
4365 raw_val = phase->MakeConX(0);
4366 }
4367 mem = new ClearArrayNode(ctl, mem, zsize, adr, raw_val, false);
4368 return phase->transform(mem);
4369 }
4370
4371 Node* ClearArrayNode::clear_memory(Node* ctl, Node* mem, Node* dest,
4372 Node* val,
4373 Node* raw_val,
4374 intptr_t start_offset,
4375 intptr_t end_offset,
4376 PhaseGVN* phase) {
4377 if (start_offset == end_offset) {
4378 // nothing to do
4379 return mem;
4380 }
4381
4382 assert((end_offset % BytesPerInt) == 0, "odd end offset");
4383 intptr_t done_offset = end_offset;
4384 if ((done_offset % BytesPerLong) != 0) {
4385 done_offset -= BytesPerInt;
4386 }
4387 if (done_offset > start_offset) {
4388 mem = clear_memory(ctl, mem, dest, val, raw_val,
4389 start_offset, phase->MakeConX(done_offset), phase);
4390 }
4391 if (done_offset < end_offset) { // emit the final 32-bit store
4392 Node* adr = new AddPNode(dest, dest, phase->MakeConX(done_offset));
4393 adr = phase->transform(adr);
4394 const TypePtr* atp = TypeRawPtr::BOTTOM;
4395 if (val != nullptr) {
4396 assert(phase->type(val)->isa_narrowoop(), "should be narrow oop");
4397 mem = new StoreNNode(ctl, mem, adr, atp, val, MemNode::unordered);
4398 } else {
4399 assert(raw_val == nullptr, "val may not be null");
4400 mem = StoreNode::make(*phase, ctl, mem, adr, atp, phase->zerocon(T_INT), T_INT, MemNode::unordered);
4401 }
4402 mem = phase->transform(mem);
4403 done_offset += BytesPerInt;
4404 }
4405 assert(done_offset == end_offset, "");
4406 return mem;
4407 }
4408
4409 //=============================================================================
4410 MemBarNode::MemBarNode(Compile* C, int alias_idx, Node* precedent)
4411 : MultiNode(TypeFunc::Parms + (precedent == nullptr? 0: 1)),
4412 _adr_type(C->get_adr_type(alias_idx)), _kind(Standalone)
4413 #ifdef ASSERT
4414 , _pair_idx(0)
4415 #endif
4416 {
4417 init_class_id(Class_MemBar);
4418 Node* top = C->top();
4419 init_req(TypeFunc::I_O,top);
4420 init_req(TypeFunc::FramePtr,top);
4421 init_req(TypeFunc::ReturnAdr,top);
4422 if (precedent != nullptr)
4423 init_req(TypeFunc::Parms, precedent);
4424 }
4425
4426 //------------------------------cmp--------------------------------------------
4427 uint MemBarNode::hash() const { return NO_HASH; }
4428 bool MemBarNode::cmp( const Node &n ) const {
4429 return (&n == this); // Always fail except on self
4430 }
4431
4432 //------------------------------make-------------------------------------------
4433 MemBarNode* MemBarNode::make(Compile* C, int opcode, int atp, Node* pn) {
4434 switch (opcode) {
4435 case Op_MemBarAcquire: return new MemBarAcquireNode(C, atp, pn);
4436 case Op_LoadFence: return new LoadFenceNode(C, atp, pn);
4437 case Op_MemBarRelease: return new MemBarReleaseNode(C, atp, pn);
4438 case Op_StoreFence: return new StoreFenceNode(C, atp, pn);
4439 case Op_MemBarStoreStore: return new MemBarStoreStoreNode(C, atp, pn);
4440 case Op_StoreStoreFence: return new StoreStoreFenceNode(C, atp, pn);
4441 case Op_MemBarAcquireLock: return new MemBarAcquireLockNode(C, atp, pn);
4442 case Op_MemBarReleaseLock: return new MemBarReleaseLockNode(C, atp, pn);
4443 case Op_MemBarVolatile: return new MemBarVolatileNode(C, atp, pn);
4444 case Op_MemBarCPUOrder: return new MemBarCPUOrderNode(C, atp, pn);
4445 case Op_OnSpinWait: return new OnSpinWaitNode(C, atp, pn);
4446 case Op_Initialize: return new InitializeNode(C, atp, pn);
4447 default: ShouldNotReachHere(); return nullptr;
4448 }
4449 }
4450
4451 void MemBarNode::remove(PhaseIterGVN *igvn) {
4452 if (outcnt() != 2) {
4453 assert(Opcode() == Op_Initialize, "Only seen when there are no use of init memory");
4454 assert(outcnt() == 1, "Only control then");
4455 }
4456 if (trailing_store() || trailing_load_store()) {
4457 MemBarNode* leading = leading_membar();
4458 if (leading != nullptr) {
4459 assert(leading->trailing_membar() == this, "inconsistent leading/trailing membars");
4460 leading->remove(igvn);
4461 }
4462 }
4463 if (proj_out_or_null(TypeFunc::Memory) != nullptr) {
4464 igvn->replace_node(proj_out(TypeFunc::Memory), in(TypeFunc::Memory));
4465 }
4466 if (proj_out_or_null(TypeFunc::Control) != nullptr) {
4467 igvn->replace_node(proj_out(TypeFunc::Control), in(TypeFunc::Control));
4468 }
4469 }
4470
4471 //------------------------------Ideal------------------------------------------
4472 // Return a node which is more "ideal" than the current node. Strip out
4473 // control copies
4474 Node *MemBarNode::Ideal(PhaseGVN *phase, bool can_reshape) {
4475 if (remove_dead_region(phase, can_reshape)) return this;
4476 // Don't bother trying to transform a dead node
4477 if (in(0) && in(0)->is_top()) {
4478 return nullptr;
4479 }
4480
4481 bool progress = false;
4482 // Eliminate volatile MemBars for scalar replaced objects.
4483 if (can_reshape && req() == (Precedent+1)) {
4484 bool eliminate = false;
4485 int opc = Opcode();
4486 if ((opc == Op_MemBarAcquire || opc == Op_MemBarVolatile)) {
4487 // Volatile field loads and stores.
4488 Node* my_mem = in(MemBarNode::Precedent);
4489 // The MembarAquire may keep an unused LoadNode alive through the Precedent edge
4490 if ((my_mem != nullptr) && (opc == Op_MemBarAcquire) && (my_mem->outcnt() == 1)) {
4491 // if the Precedent is a decodeN and its input (a Load) is used at more than one place,
4492 // replace this Precedent (decodeN) with the Load instead.
4493 if ((my_mem->Opcode() == Op_DecodeN) && (my_mem->in(1)->outcnt() > 1)) {
4494 Node* load_node = my_mem->in(1);
4495 set_req(MemBarNode::Precedent, load_node);
4496 phase->is_IterGVN()->_worklist.push(my_mem);
4497 my_mem = load_node;
4498 } else {
4499 assert(my_mem->unique_out() == this, "sanity");
4500 assert(!trailing_load_store(), "load store node can't be eliminated");
4501 del_req(Precedent);
4502 phase->is_IterGVN()->_worklist.push(my_mem); // remove dead node later
4503 my_mem = nullptr;
4504 }
4505 progress = true;
4506 }
4507 if (my_mem != nullptr && my_mem->is_Mem()) {
4508 const TypeOopPtr* t_oop = my_mem->in(MemNode::Address)->bottom_type()->isa_oopptr();
4509 // Check for scalar replaced object reference.
4510 if( t_oop != nullptr && t_oop->is_known_instance_field() &&
4511 t_oop->offset() != Type::OffsetBot &&
4512 t_oop->offset() != Type::OffsetTop) {
4513 eliminate = true;
4514 }
4515 }
4516 } else if (opc == Op_MemBarRelease || (UseStoreStoreForCtor && opc == Op_MemBarStoreStore)) {
4517 // Final field stores.
4518 Node* alloc = AllocateNode::Ideal_allocation(in(MemBarNode::Precedent));
4519 if ((alloc != nullptr) && alloc->is_Allocate() &&
4520 alloc->as_Allocate()->does_not_escape_thread()) {
4521 // The allocated object does not escape.
4522 eliminate = true;
4523 }
4524 }
4525 if (eliminate) {
4526 // Replace MemBar projections by its inputs.
4527 PhaseIterGVN* igvn = phase->is_IterGVN();
4528 remove(igvn);
4529 // Must return either the original node (now dead) or a new node
4530 // (Do not return a top here, since that would break the uniqueness of top.)
4531 return new ConINode(TypeInt::ZERO);
4532 }
4533 }
4534 return progress ? this : nullptr;
4535 }
4536
4537 //------------------------------Value------------------------------------------
4538 const Type* MemBarNode::Value(PhaseGVN* phase) const {
4539 if( !in(0) ) return Type::TOP;
4540 if( phase->type(in(0)) == Type::TOP )
4541 return Type::TOP;
4542 return TypeTuple::MEMBAR;
4543 }
4544
4545 //------------------------------match------------------------------------------
4546 // Construct projections for memory.
4547 Node *MemBarNode::match(const ProjNode *proj, const Matcher *m, const RegMask* mask) {
4548 switch (proj->_con) {
4549 case TypeFunc::Control:
4550 case TypeFunc::Memory:
4551 return new MachProjNode(this,proj->_con,RegMask::Empty,MachProjNode::unmatched_proj);
4552 }
4553 ShouldNotReachHere();
4554 return nullptr;
4555 }
4556
4557 void MemBarNode::set_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4558 trailing->_kind = TrailingStore;
4559 leading->_kind = LeadingStore;
4560 #ifdef ASSERT
4561 trailing->_pair_idx = leading->_idx;
4562 leading->_pair_idx = leading->_idx;
4563 #endif
4564 }
4565
4566 void MemBarNode::set_load_store_pair(MemBarNode* leading, MemBarNode* trailing) {
4567 trailing->_kind = TrailingLoadStore;
4568 leading->_kind = LeadingLoadStore;
4569 #ifdef ASSERT
4570 trailing->_pair_idx = leading->_idx;
4571 leading->_pair_idx = leading->_idx;
4572 #endif
4573 }
4574
4575 MemBarNode* MemBarNode::trailing_membar() const {
4576 ResourceMark rm;
4577 Node* trailing = (Node*)this;
4578 VectorSet seen;
4579 Node_Stack multis(0);
4580 do {
4581 Node* c = trailing;
4582 uint i = 0;
4583 do {
4584 trailing = nullptr;
4585 for (; i < c->outcnt(); i++) {
4586 Node* next = c->raw_out(i);
4587 if (next != c && next->is_CFG()) {
4588 if (c->is_MultiBranch()) {
4589 if (multis.node() == c) {
4590 multis.set_index(i+1);
4591 } else {
4592 multis.push(c, i+1);
4593 }
4594 }
4595 trailing = next;
4596 break;
4597 }
4598 }
4599 if (trailing != nullptr && !seen.test_set(trailing->_idx)) {
4600 break;
4601 }
4602 while (multis.size() > 0) {
4603 c = multis.node();
4604 i = multis.index();
4605 if (i < c->req()) {
4606 break;
4607 }
4608 multis.pop();
4609 }
4610 } while (multis.size() > 0);
4611 } while (!trailing->is_MemBar() || !trailing->as_MemBar()->trailing());
4612
4613 MemBarNode* mb = trailing->as_MemBar();
4614 assert((mb->_kind == TrailingStore && _kind == LeadingStore) ||
4615 (mb->_kind == TrailingLoadStore && _kind == LeadingLoadStore), "bad trailing membar");
4616 assert(mb->_pair_idx == _pair_idx, "bad trailing membar");
4617 return mb;
4618 }
4619
4620 MemBarNode* MemBarNode::leading_membar() const {
4621 ResourceMark rm;
4622 VectorSet seen;
4623 Node_Stack regions(0);
4624 Node* leading = in(0);
4625 while (leading != nullptr && (!leading->is_MemBar() || !leading->as_MemBar()->leading())) {
4626 while (leading == nullptr || leading->is_top() || seen.test_set(leading->_idx)) {
4627 leading = nullptr;
4628 while (regions.size() > 0 && leading == nullptr) {
4629 Node* r = regions.node();
4630 uint i = regions.index();
4631 if (i < r->req()) {
4632 leading = r->in(i);
4633 regions.set_index(i+1);
4634 } else {
4635 regions.pop();
4636 }
4637 }
4638 if (leading == nullptr) {
4639 assert(regions.size() == 0, "all paths should have been tried");
4640 return nullptr;
4641 }
4642 }
4643 if (leading->is_Region()) {
4644 regions.push(leading, 2);
4645 leading = leading->in(1);
4646 } else {
4647 leading = leading->in(0);
4648 }
4649 }
4650 #ifdef ASSERT
4651 Unique_Node_List wq;
4652 wq.push((Node*)this);
4653 uint found = 0;
4654 for (uint i = 0; i < wq.size(); i++) {
4655 Node* n = wq.at(i);
4656 if (n->is_Region()) {
4657 for (uint j = 1; j < n->req(); j++) {
4658 Node* in = n->in(j);
4659 if (in != nullptr && !in->is_top()) {
4660 wq.push(in);
4661 }
4662 }
4663 } else {
4664 if (n->is_MemBar() && n->as_MemBar()->leading()) {
4665 assert(n == leading, "consistency check failed");
4666 found++;
4667 } else {
4668 Node* in = n->in(0);
4669 if (in != nullptr && !in->is_top()) {
4670 wq.push(in);
4671 }
4672 }
4673 }
4674 }
4675 assert(found == 1 || (found == 0 && leading == nullptr), "consistency check failed");
4676 #endif
4677 if (leading == nullptr) {
4678 return nullptr;
4679 }
4680 MemBarNode* mb = leading->as_MemBar();
4681 assert((mb->_kind == LeadingStore && _kind == TrailingStore) ||
4682 (mb->_kind == LeadingLoadStore && _kind == TrailingLoadStore), "bad leading membar");
4683 assert(mb->_pair_idx == _pair_idx, "bad leading membar");
4684 return mb;
4685 }
4686
4687
4688 //===========================InitializeNode====================================
4689 // SUMMARY:
4690 // This node acts as a memory barrier on raw memory, after some raw stores.
4691 // The 'cooked' oop value feeds from the Initialize, not the Allocation.
4692 // The Initialize can 'capture' suitably constrained stores as raw inits.
4693 // It can coalesce related raw stores into larger units (called 'tiles').
4694 // It can avoid zeroing new storage for memory units which have raw inits.
4695 // At macro-expansion, it is marked 'complete', and does not optimize further.
4696 //
4697 // EXAMPLE:
4698 // The object 'new short[2]' occupies 16 bytes in a 32-bit machine.
4699 // ctl = incoming control; mem* = incoming memory
4700 // (Note: A star * on a memory edge denotes I/O and other standard edges.)
4701 // First allocate uninitialized memory and fill in the header:
4702 // alloc = (Allocate ctl mem* 16 #short[].klass ...)
4703 // ctl := alloc.Control; mem* := alloc.Memory*
4704 // rawmem = alloc.Memory; rawoop = alloc.RawAddress
4705 // Then initialize to zero the non-header parts of the raw memory block:
4706 // init = (Initialize alloc.Control alloc.Memory* alloc.RawAddress)
4707 // ctl := init.Control; mem.SLICE(#short[*]) := init.Memory
4708 // After the initialize node executes, the object is ready for service:
4709 // oop := (CheckCastPP init.Control alloc.RawAddress #short[])
4710 // Suppose its body is immediately initialized as {1,2}:
4711 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
4712 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
4713 // mem.SLICE(#short[*]) := store2
4714 //
4715 // DETAILS:
4716 // An InitializeNode collects and isolates object initialization after
4717 // an AllocateNode and before the next possible safepoint. As a
4718 // memory barrier (MemBarNode), it keeps critical stores from drifting
4719 // down past any safepoint or any publication of the allocation.
4720 // Before this barrier, a newly-allocated object may have uninitialized bits.
4721 // After this barrier, it may be treated as a real oop, and GC is allowed.
4722 //
4723 // The semantics of the InitializeNode include an implicit zeroing of
4724 // the new object from object header to the end of the object.
4725 // (The object header and end are determined by the AllocateNode.)
4726 //
4727 // Certain stores may be added as direct inputs to the InitializeNode.
4728 // These stores must update raw memory, and they must be to addresses
4729 // derived from the raw address produced by AllocateNode, and with
4730 // a constant offset. They must be ordered by increasing offset.
4731 // The first one is at in(RawStores), the last at in(req()-1).
4732 // Unlike most memory operations, they are not linked in a chain,
4733 // but are displayed in parallel as users of the rawmem output of
4734 // the allocation.
4735 //
4736 // (See comments in InitializeNode::capture_store, which continue
4737 // the example given above.)
4738 //
4739 // When the associated Allocate is macro-expanded, the InitializeNode
4740 // may be rewritten to optimize collected stores. A ClearArrayNode
4741 // may also be created at that point to represent any required zeroing.
4742 // The InitializeNode is then marked 'complete', prohibiting further
4743 // capturing of nearby memory operations.
4744 //
4745 // During macro-expansion, all captured initializations which store
4746 // constant values of 32 bits or smaller are coalesced (if advantageous)
4747 // into larger 'tiles' 32 or 64 bits. This allows an object to be
4748 // initialized in fewer memory operations. Memory words which are
4749 // covered by neither tiles nor non-constant stores are pre-zeroed
4750 // by explicit stores of zero. (The code shape happens to do all
4751 // zeroing first, then all other stores, with both sequences occurring
4752 // in order of ascending offsets.)
4753 //
4754 // Alternatively, code may be inserted between an AllocateNode and its
4755 // InitializeNode, to perform arbitrary initialization of the new object.
4756 // E.g., the object copying intrinsics insert complex data transfers here.
4757 // The initialization must then be marked as 'complete' disable the
4758 // built-in zeroing semantics and the collection of initializing stores.
4759 //
4760 // While an InitializeNode is incomplete, reads from the memory state
4761 // produced by it are optimizable if they match the control edge and
4762 // new oop address associated with the allocation/initialization.
4763 // They return a stored value (if the offset matches) or else zero.
4764 // A write to the memory state, if it matches control and address,
4765 // and if it is to a constant offset, may be 'captured' by the
4766 // InitializeNode. It is cloned as a raw memory operation and rewired
4767 // inside the initialization, to the raw oop produced by the allocation.
4768 // Operations on addresses which are provably distinct (e.g., to
4769 // other AllocateNodes) are allowed to bypass the initialization.
4770 //
4771 // The effect of all this is to consolidate object initialization
4772 // (both arrays and non-arrays, both piecewise and bulk) into a
4773 // single location, where it can be optimized as a unit.
4774 //
4775 // Only stores with an offset less than TrackedInitializationLimit words
4776 // will be considered for capture by an InitializeNode. This puts a
4777 // reasonable limit on the complexity of optimized initializations.
4778
4779 //---------------------------InitializeNode------------------------------------
4780 InitializeNode::InitializeNode(Compile* C, int adr_type, Node* rawoop)
4781 : MemBarNode(C, adr_type, rawoop),
4782 _is_complete(Incomplete), _does_not_escape(false)
4783 {
4784 init_class_id(Class_Initialize);
4785
4786 assert(adr_type == Compile::AliasIdxRaw, "only valid atp");
4787 assert(in(RawAddress) == rawoop, "proper init");
4788 // Note: allocation() can be null, for secondary initialization barriers
4789 }
4790
4791 // Since this node is not matched, it will be processed by the
4792 // register allocator. Declare that there are no constraints
4793 // on the allocation of the RawAddress edge.
4794 const RegMask &InitializeNode::in_RegMask(uint idx) const {
4795 // This edge should be set to top, by the set_complete. But be conservative.
4796 if (idx == InitializeNode::RawAddress)
4797 return *(Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()]);
4798 return RegMask::Empty;
4799 }
4800
4801 Node* InitializeNode::memory(uint alias_idx) {
4802 Node* mem = in(Memory);
4803 if (mem->is_MergeMem()) {
4804 return mem->as_MergeMem()->memory_at(alias_idx);
4805 } else {
4806 // incoming raw memory is not split
4807 return mem;
4808 }
4809 }
4810
4811 bool InitializeNode::is_non_zero() {
4812 if (is_complete()) return false;
4813 remove_extra_zeroes();
4814 return (req() > RawStores);
4815 }
4816
4817 void InitializeNode::set_complete(PhaseGVN* phase) {
4818 assert(!is_complete(), "caller responsibility");
4819 _is_complete = Complete;
4820
4821 // After this node is complete, it contains a bunch of
4822 // raw-memory initializations. There is no need for
4823 // it to have anything to do with non-raw memory effects.
4824 // Therefore, tell all non-raw users to re-optimize themselves,
4825 // after skipping the memory effects of this initialization.
4826 PhaseIterGVN* igvn = phase->is_IterGVN();
4827 if (igvn) igvn->add_users_to_worklist(this);
4828 }
4829
4830 // convenience function
4831 // return false if the init contains any stores already
4832 bool AllocateNode::maybe_set_complete(PhaseGVN* phase) {
4833 InitializeNode* init = initialization();
4834 if (init == nullptr || init->is_complete()) {
4835 return false;
4836 }
4837 init->remove_extra_zeroes();
4838 // for now, if this allocation has already collected any inits, bail:
4839 if (init->is_non_zero()) return false;
4840 init->set_complete(phase);
4841 return true;
4842 }
4843
4844 void InitializeNode::remove_extra_zeroes() {
4845 if (req() == RawStores) return;
4846 Node* zmem = zero_memory();
4847 uint fill = RawStores;
4848 for (uint i = fill; i < req(); i++) {
4849 Node* n = in(i);
4850 if (n->is_top() || n == zmem) continue; // skip
4851 if (fill < i) set_req(fill, n); // compact
4852 ++fill;
4853 }
4854 // delete any empty spaces created:
4855 while (fill < req()) {
4856 del_req(fill);
4857 }
4858 }
4859
4860 // Helper for remembering which stores go with which offsets.
4861 intptr_t InitializeNode::get_store_offset(Node* st, PhaseValues* phase) {
4862 if (!st->is_Store()) return -1; // can happen to dead code via subsume_node
4863 intptr_t offset = -1;
4864 Node* base = AddPNode::Ideal_base_and_offset(st->in(MemNode::Address),
4865 phase, offset);
4866 if (base == nullptr) return -1; // something is dead,
4867 if (offset < 0) return -1; // dead, dead
4868 return offset;
4869 }
4870
4871 // Helper for proving that an initialization expression is
4872 // "simple enough" to be folded into an object initialization.
4873 // Attempts to prove that a store's initial value 'n' can be captured
4874 // within the initialization without creating a vicious cycle, such as:
4875 // { Foo p = new Foo(); p.next = p; }
4876 // True for constants and parameters and small combinations thereof.
4877 bool InitializeNode::detect_init_independence(Node* value, PhaseGVN* phase) {
4878 ResourceMark rm;
4879 Unique_Node_List worklist;
4880 worklist.push(value);
4881
4882 uint complexity_limit = 20;
4883 for (uint j = 0; j < worklist.size(); j++) {
4884 if (j >= complexity_limit) {
4885 return false; // Bail out if processed too many nodes
4886 }
4887
4888 Node* n = worklist.at(j);
4889 if (n == nullptr) continue; // (can this really happen?)
4890 if (n->is_Proj()) n = n->in(0);
4891 if (n == this) return false; // found a cycle
4892 if (n->is_Con()) continue;
4893 if (n->is_Start()) continue; // params, etc., are OK
4894 if (n->is_Root()) continue; // even better
4895
4896 // There cannot be any dependency if 'n' is a CFG node that dominates the current allocation
4897 if (n->is_CFG() && phase->is_dominator(n, allocation())) {
4898 continue;
4899 }
4900
4901 Node* ctl = n->in(0);
4902 if (ctl != nullptr && !ctl->is_top()) {
4903 if (ctl->is_Proj()) ctl = ctl->in(0);
4904 if (ctl == this) return false;
4905
4906 // If we already know that the enclosing memory op is pinned right after
4907 // the init, then any control flow that the store has picked up
4908 // must have preceded the init, or else be equal to the init.
4909 // Even after loop optimizations (which might change control edges)
4910 // a store is never pinned *before* the availability of its inputs.
4911 if (!MemNode::all_controls_dominate(n, this)) {
4912 return false; // failed to prove a good control
4913 }
4914 }
4915
4916 // Check data edges for possible dependencies on 'this'.
4917 for (uint i = 1; i < n->req(); i++) {
4918 Node* m = n->in(i);
4919 if (m == nullptr || m == n || m->is_top()) continue;
4920
4921 // Only process data inputs once
4922 worklist.push(m);
4923 }
4924 }
4925
4926 return true;
4927 }
4928
4929 // Here are all the checks a Store must pass before it can be moved into
4930 // an initialization. Returns zero if a check fails.
4931 // On success, returns the (constant) offset to which the store applies,
4932 // within the initialized memory.
4933 intptr_t InitializeNode::can_capture_store(StoreNode* st, PhaseGVN* phase, bool can_reshape) {
4934 const int FAIL = 0;
4935 if (st->req() != MemNode::ValueIn + 1)
4936 return FAIL; // an inscrutable StoreNode (card mark?)
4937 Node* ctl = st->in(MemNode::Control);
4938 if (!(ctl != nullptr && ctl->is_Proj() && ctl->in(0) == this))
4939 return FAIL; // must be unconditional after the initialization
4940 Node* mem = st->in(MemNode::Memory);
4941 if (!(mem->is_Proj() && mem->in(0) == this))
4942 return FAIL; // must not be preceded by other stores
4943 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
4944 if ((st->Opcode() == Op_StoreP || st->Opcode() == Op_StoreN) &&
4945 !bs->can_initialize_object(st)) {
4946 return FAIL;
4947 }
4948 Node* adr = st->in(MemNode::Address);
4949 intptr_t offset;
4950 AllocateNode* alloc = AllocateNode::Ideal_allocation(adr, phase, offset);
4951 if (alloc == nullptr)
4952 return FAIL; // inscrutable address
4953 if (alloc != allocation())
4954 return FAIL; // wrong allocation! (store needs to float up)
4955 int size_in_bytes = st->memory_size();
4956 if ((size_in_bytes != 0) && (offset % size_in_bytes) != 0) {
4957 return FAIL; // mismatched access
4958 }
4959 Node* val = st->in(MemNode::ValueIn);
4960
4961 if (!detect_init_independence(val, phase))
4962 return FAIL; // stored value must be 'simple enough'
4963
4964 // The Store can be captured only if nothing after the allocation
4965 // and before the Store is using the memory location that the store
4966 // overwrites.
4967 bool failed = false;
4968 // If is_complete_with_arraycopy() is true the shape of the graph is
4969 // well defined and is safe so no need for extra checks.
4970 if (!is_complete_with_arraycopy()) {
4971 // We are going to look at each use of the memory state following
4972 // the allocation to make sure nothing reads the memory that the
4973 // Store writes.
4974 const TypePtr* t_adr = phase->type(adr)->isa_ptr();
4975 int alias_idx = phase->C->get_alias_index(t_adr);
4976 ResourceMark rm;
4977 Unique_Node_List mems;
4978 mems.push(mem);
4979 Node* unique_merge = nullptr;
4980 for (uint next = 0; next < mems.size(); ++next) {
4981 Node *m = mems.at(next);
4982 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
4983 Node *n = m->fast_out(j);
4984 if (n->outcnt() == 0) {
4985 continue;
4986 }
4987 if (n == st) {
4988 continue;
4989 } else if (n->in(0) != nullptr && n->in(0) != ctl) {
4990 // If the control of this use is different from the control
4991 // of the Store which is right after the InitializeNode then
4992 // this node cannot be between the InitializeNode and the
4993 // Store.
4994 continue;
4995 } else if (n->is_MergeMem()) {
4996 if (n->as_MergeMem()->memory_at(alias_idx) == m) {
4997 // We can hit a MergeMemNode (that will likely go away
4998 // later) that is a direct use of the memory state
4999 // following the InitializeNode on the same slice as the
5000 // store node that we'd like to capture. We need to check
5001 // the uses of the MergeMemNode.
5002 mems.push(n);
5003 }
5004 } else if (n->is_Mem()) {
5005 Node* other_adr = n->in(MemNode::Address);
5006 if (other_adr == adr) {
5007 failed = true;
5008 break;
5009 } else {
5010 const TypePtr* other_t_adr = phase->type(other_adr)->isa_ptr();
5011 if (other_t_adr != nullptr) {
5012 int other_alias_idx = phase->C->get_alias_index(other_t_adr);
5013 if (other_alias_idx == alias_idx) {
5014 // A load from the same memory slice as the store right
5015 // after the InitializeNode. We check the control of the
5016 // object/array that is loaded from. If it's the same as
5017 // the store control then we cannot capture the store.
5018 assert(!n->is_Store(), "2 stores to same slice on same control?");
5019 Node* base = other_adr;
5020 if (base->is_Phi()) {
5021 // In rare case, base may be a PhiNode and it may read
5022 // the same memory slice between InitializeNode and store.
5023 failed = true;
5024 break;
5025 }
5026 assert(base->is_AddP(), "should be addp but is %s", base->Name());
5027 base = base->in(AddPNode::Base);
5028 if (base != nullptr) {
5029 base = base->uncast();
5030 if (base->is_Proj() && base->in(0) == alloc) {
5031 failed = true;
5032 break;
5033 }
5034 }
5035 }
5036 }
5037 }
5038 } else {
5039 failed = true;
5040 break;
5041 }
5042 }
5043 }
5044 }
5045 if (failed) {
5046 if (!can_reshape) {
5047 // We decided we couldn't capture the store during parsing. We
5048 // should try again during the next IGVN once the graph is
5049 // cleaner.
5050 phase->C->record_for_igvn(st);
5051 }
5052 return FAIL;
5053 }
5054
5055 return offset; // success
5056 }
5057
5058 // Find the captured store in(i) which corresponds to the range
5059 // [start..start+size) in the initialized object.
5060 // If there is one, return its index i. If there isn't, return the
5061 // negative of the index where it should be inserted.
5062 // Return 0 if the queried range overlaps an initialization boundary
5063 // or if dead code is encountered.
5064 // If size_in_bytes is zero, do not bother with overlap checks.
5065 int InitializeNode::captured_store_insertion_point(intptr_t start,
5066 int size_in_bytes,
5067 PhaseValues* phase) {
5068 const int FAIL = 0, MAX_STORE = MAX2(BytesPerLong, (int)MaxVectorSize);
5069
5070 if (is_complete())
5071 return FAIL; // arraycopy got here first; punt
5072
5073 assert(allocation() != nullptr, "must be present");
5074
5075 // no negatives, no header fields:
5076 if (start < (intptr_t) allocation()->minimum_header_size()) return FAIL;
5077
5078 // after a certain size, we bail out on tracking all the stores:
5079 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5080 if (start >= ti_limit) return FAIL;
5081
5082 for (uint i = InitializeNode::RawStores, limit = req(); ; ) {
5083 if (i >= limit) return -(int)i; // not found; here is where to put it
5084
5085 Node* st = in(i);
5086 intptr_t st_off = get_store_offset(st, phase);
5087 if (st_off < 0) {
5088 if (st != zero_memory()) {
5089 return FAIL; // bail out if there is dead garbage
5090 }
5091 } else if (st_off > start) {
5092 // ...we are done, since stores are ordered
5093 if (st_off < start + size_in_bytes) {
5094 return FAIL; // the next store overlaps
5095 }
5096 return -(int)i; // not found; here is where to put it
5097 } else if (st_off < start) {
5098 assert(st->as_Store()->memory_size() <= MAX_STORE, "");
5099 if (size_in_bytes != 0 &&
5100 start < st_off + MAX_STORE &&
5101 start < st_off + st->as_Store()->memory_size()) {
5102 return FAIL; // the previous store overlaps
5103 }
5104 } else {
5105 if (size_in_bytes != 0 &&
5106 st->as_Store()->memory_size() != size_in_bytes) {
5107 return FAIL; // mismatched store size
5108 }
5109 return i;
5110 }
5111
5112 ++i;
5113 }
5114 }
5115
5116 // Look for a captured store which initializes at the offset 'start'
5117 // with the given size. If there is no such store, and no other
5118 // initialization interferes, then return zero_memory (the memory
5119 // projection of the AllocateNode).
5120 Node* InitializeNode::find_captured_store(intptr_t start, int size_in_bytes,
5121 PhaseValues* phase) {
5122 assert(stores_are_sane(phase), "");
5123 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5124 if (i == 0) {
5125 return nullptr; // something is dead
5126 } else if (i < 0) {
5127 return zero_memory(); // just primordial zero bits here
5128 } else {
5129 Node* st = in(i); // here is the store at this position
5130 assert(get_store_offset(st->as_Store(), phase) == start, "sanity");
5131 return st;
5132 }
5133 }
5134
5135 // Create, as a raw pointer, an address within my new object at 'offset'.
5136 Node* InitializeNode::make_raw_address(intptr_t offset,
5137 PhaseGVN* phase) {
5138 Node* addr = in(RawAddress);
5139 if (offset != 0) {
5140 Compile* C = phase->C;
5141 addr = phase->transform( new AddPNode(C->top(), addr,
5142 phase->MakeConX(offset)) );
5143 }
5144 return addr;
5145 }
5146
5147 // Clone the given store, converting it into a raw store
5148 // initializing a field or element of my new object.
5149 // Caller is responsible for retiring the original store,
5150 // with subsume_node or the like.
5151 //
5152 // From the example above InitializeNode::InitializeNode,
5153 // here are the old stores to be captured:
5154 // store1 = (StoreC init.Control init.Memory (+ oop 12) 1)
5155 // store2 = (StoreC init.Control store1 (+ oop 14) 2)
5156 //
5157 // Here is the changed code; note the extra edges on init:
5158 // alloc = (Allocate ...)
5159 // rawoop = alloc.RawAddress
5160 // rawstore1 = (StoreC alloc.Control alloc.Memory (+ rawoop 12) 1)
5161 // rawstore2 = (StoreC alloc.Control alloc.Memory (+ rawoop 14) 2)
5162 // init = (Initialize alloc.Control alloc.Memory rawoop
5163 // rawstore1 rawstore2)
5164 //
5165 Node* InitializeNode::capture_store(StoreNode* st, intptr_t start,
5166 PhaseGVN* phase, bool can_reshape) {
5167 assert(stores_are_sane(phase), "");
5168
5169 if (start < 0) return nullptr;
5170 assert(can_capture_store(st, phase, can_reshape) == start, "sanity");
5171
5172 Compile* C = phase->C;
5173 int size_in_bytes = st->memory_size();
5174 int i = captured_store_insertion_point(start, size_in_bytes, phase);
5175 if (i == 0) return nullptr; // bail out
5176 Node* prev_mem = nullptr; // raw memory for the captured store
5177 if (i > 0) {
5178 prev_mem = in(i); // there is a pre-existing store under this one
5179 set_req(i, C->top()); // temporarily disconnect it
5180 // See StoreNode::Ideal 'st->outcnt() == 1' for the reason to disconnect.
5181 } else {
5182 i = -i; // no pre-existing store
5183 prev_mem = zero_memory(); // a slice of the newly allocated object
5184 if (i > InitializeNode::RawStores && in(i-1) == prev_mem)
5185 set_req(--i, C->top()); // reuse this edge; it has been folded away
5186 else
5187 ins_req(i, C->top()); // build a new edge
5188 }
5189 Node* new_st = st->clone();
5190 BarrierSetC2* bs = BarrierSet::barrier_set()->barrier_set_c2();
5191 new_st->set_req(MemNode::Control, in(Control));
5192 new_st->set_req(MemNode::Memory, prev_mem);
5193 new_st->set_req(MemNode::Address, make_raw_address(start, phase));
5194 bs->eliminate_gc_barrier_data(new_st);
5195 new_st = phase->transform(new_st);
5196
5197 // At this point, new_st might have swallowed a pre-existing store
5198 // at the same offset, or perhaps new_st might have disappeared,
5199 // if it redundantly stored the same value (or zero to fresh memory).
5200
5201 // In any case, wire it in:
5202 PhaseIterGVN* igvn = phase->is_IterGVN();
5203 if (igvn) {
5204 igvn->rehash_node_delayed(this);
5205 }
5206 set_req(i, new_st);
5207
5208 // The caller may now kill the old guy.
5209 DEBUG_ONLY(Node* check_st = find_captured_store(start, size_in_bytes, phase));
5210 assert(check_st == new_st || check_st == nullptr, "must be findable");
5211 assert(!is_complete(), "");
5212 return new_st;
5213 }
5214
5215 static bool store_constant(jlong* tiles, int num_tiles,
5216 intptr_t st_off, int st_size,
5217 jlong con) {
5218 if ((st_off & (st_size-1)) != 0)
5219 return false; // strange store offset (assume size==2**N)
5220 address addr = (address)tiles + st_off;
5221 assert(st_off >= 0 && addr+st_size <= (address)&tiles[num_tiles], "oob");
5222 switch (st_size) {
5223 case sizeof(jbyte): *(jbyte*) addr = (jbyte) con; break;
5224 case sizeof(jchar): *(jchar*) addr = (jchar) con; break;
5225 case sizeof(jint): *(jint*) addr = (jint) con; break;
5226 case sizeof(jlong): *(jlong*) addr = (jlong) con; break;
5227 default: return false; // strange store size (detect size!=2**N here)
5228 }
5229 return true; // return success to caller
5230 }
5231
5232 // Coalesce subword constants into int constants and possibly
5233 // into long constants. The goal, if the CPU permits,
5234 // is to initialize the object with a small number of 64-bit tiles.
5235 // Also, convert floating-point constants to bit patterns.
5236 // Non-constants are not relevant to this pass.
5237 //
5238 // In terms of the running example on InitializeNode::InitializeNode
5239 // and InitializeNode::capture_store, here is the transformation
5240 // of rawstore1 and rawstore2 into rawstore12:
5241 // alloc = (Allocate ...)
5242 // rawoop = alloc.RawAddress
5243 // tile12 = 0x00010002
5244 // rawstore12 = (StoreI alloc.Control alloc.Memory (+ rawoop 12) tile12)
5245 // init = (Initialize alloc.Control alloc.Memory rawoop rawstore12)
5246 //
5247 void
5248 InitializeNode::coalesce_subword_stores(intptr_t header_size,
5249 Node* size_in_bytes,
5250 PhaseGVN* phase) {
5251 Compile* C = phase->C;
5252
5253 assert(stores_are_sane(phase), "");
5254 // Note: After this pass, they are not completely sane,
5255 // since there may be some overlaps.
5256
5257 int old_subword = 0, old_long = 0, new_int = 0, new_long = 0;
5258
5259 intptr_t ti_limit = (TrackedInitializationLimit * HeapWordSize);
5260 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, ti_limit);
5261 size_limit = MIN2(size_limit, ti_limit);
5262 size_limit = align_up(size_limit, BytesPerLong);
5263 int num_tiles = size_limit / BytesPerLong;
5264
5265 // allocate space for the tile map:
5266 const int small_len = DEBUG_ONLY(true ? 3 :) 30; // keep stack frames small
5267 jlong tiles_buf[small_len];
5268 Node* nodes_buf[small_len];
5269 jlong inits_buf[small_len];
5270 jlong* tiles = ((num_tiles <= small_len) ? &tiles_buf[0]
5271 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5272 Node** nodes = ((num_tiles <= small_len) ? &nodes_buf[0]
5273 : NEW_RESOURCE_ARRAY(Node*, num_tiles));
5274 jlong* inits = ((num_tiles <= small_len) ? &inits_buf[0]
5275 : NEW_RESOURCE_ARRAY(jlong, num_tiles));
5276 // tiles: exact bitwise model of all primitive constants
5277 // nodes: last constant-storing node subsumed into the tiles model
5278 // inits: which bytes (in each tile) are touched by any initializations
5279
5280 //// Pass A: Fill in the tile model with any relevant stores.
5281
5282 Copy::zero_to_bytes(tiles, sizeof(tiles[0]) * num_tiles);
5283 Copy::zero_to_bytes(nodes, sizeof(nodes[0]) * num_tiles);
5284 Copy::zero_to_bytes(inits, sizeof(inits[0]) * num_tiles);
5285 Node* zmem = zero_memory(); // initially zero memory state
5286 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5287 Node* st = in(i);
5288 intptr_t st_off = get_store_offset(st, phase);
5289
5290 // Figure out the store's offset and constant value:
5291 if (st_off < header_size) continue; //skip (ignore header)
5292 if (st->in(MemNode::Memory) != zmem) continue; //skip (odd store chain)
5293 int st_size = st->as_Store()->memory_size();
5294 if (st_off + st_size > size_limit) break;
5295
5296 // Record which bytes are touched, whether by constant or not.
5297 if (!store_constant(inits, num_tiles, st_off, st_size, (jlong) -1))
5298 continue; // skip (strange store size)
5299
5300 const Type* val = phase->type(st->in(MemNode::ValueIn));
5301 if (!val->singleton()) continue; //skip (non-con store)
5302 BasicType type = val->basic_type();
5303
5304 jlong con = 0;
5305 switch (type) {
5306 case T_INT: con = val->is_int()->get_con(); break;
5307 case T_LONG: con = val->is_long()->get_con(); break;
5308 case T_FLOAT: con = jint_cast(val->getf()); break;
5309 case T_DOUBLE: con = jlong_cast(val->getd()); break;
5310 default: continue; //skip (odd store type)
5311 }
5312
5313 if (type == T_LONG && Matcher::isSimpleConstant64(con) &&
5314 st->Opcode() == Op_StoreL) {
5315 continue; // This StoreL is already optimal.
5316 }
5317
5318 // Store down the constant.
5319 store_constant(tiles, num_tiles, st_off, st_size, con);
5320
5321 intptr_t j = st_off >> LogBytesPerLong;
5322
5323 if (type == T_INT && st_size == BytesPerInt
5324 && (st_off & BytesPerInt) == BytesPerInt) {
5325 jlong lcon = tiles[j];
5326 if (!Matcher::isSimpleConstant64(lcon) &&
5327 st->Opcode() == Op_StoreI) {
5328 // This StoreI is already optimal by itself.
5329 jint* intcon = (jint*) &tiles[j];
5330 intcon[1] = 0; // undo the store_constant()
5331
5332 // If the previous store is also optimal by itself, back up and
5333 // undo the action of the previous loop iteration... if we can.
5334 // But if we can't, just let the previous half take care of itself.
5335 st = nodes[j];
5336 st_off -= BytesPerInt;
5337 con = intcon[0];
5338 if (con != 0 && st != nullptr && st->Opcode() == Op_StoreI) {
5339 assert(st_off >= header_size, "still ignoring header");
5340 assert(get_store_offset(st, phase) == st_off, "must be");
5341 assert(in(i-1) == zmem, "must be");
5342 DEBUG_ONLY(const Type* tcon = phase->type(st->in(MemNode::ValueIn)));
5343 assert(con == tcon->is_int()->get_con(), "must be");
5344 // Undo the effects of the previous loop trip, which swallowed st:
5345 intcon[0] = 0; // undo store_constant()
5346 set_req(i-1, st); // undo set_req(i, zmem)
5347 nodes[j] = nullptr; // undo nodes[j] = st
5348 --old_subword; // undo ++old_subword
5349 }
5350 continue; // This StoreI is already optimal.
5351 }
5352 }
5353
5354 // This store is not needed.
5355 set_req(i, zmem);
5356 nodes[j] = st; // record for the moment
5357 if (st_size < BytesPerLong) // something has changed
5358 ++old_subword; // includes int/float, but who's counting...
5359 else ++old_long;
5360 }
5361
5362 if ((old_subword + old_long) == 0)
5363 return; // nothing more to do
5364
5365 //// Pass B: Convert any non-zero tiles into optimal constant stores.
5366 // Be sure to insert them before overlapping non-constant stores.
5367 // (E.g., byte[] x = { 1,2,y,4 } => x[int 0] = 0x01020004, x[2]=y.)
5368 for (int j = 0; j < num_tiles; j++) {
5369 jlong con = tiles[j];
5370 jlong init = inits[j];
5371 if (con == 0) continue;
5372 jint con0, con1; // split the constant, address-wise
5373 jint init0, init1; // split the init map, address-wise
5374 { union { jlong con; jint intcon[2]; } u;
5375 u.con = con;
5376 con0 = u.intcon[0];
5377 con1 = u.intcon[1];
5378 u.con = init;
5379 init0 = u.intcon[0];
5380 init1 = u.intcon[1];
5381 }
5382
5383 Node* old = nodes[j];
5384 assert(old != nullptr, "need the prior store");
5385 intptr_t offset = (j * BytesPerLong);
5386
5387 bool split = !Matcher::isSimpleConstant64(con);
5388
5389 if (offset < header_size) {
5390 assert(offset + BytesPerInt >= header_size, "second int counts");
5391 assert(*(jint*)&tiles[j] == 0, "junk in header");
5392 split = true; // only the second word counts
5393 // Example: int a[] = { 42 ... }
5394 } else if (con0 == 0 && init0 == -1) {
5395 split = true; // first word is covered by full inits
5396 // Example: int a[] = { ... foo(), 42 ... }
5397 } else if (con1 == 0 && init1 == -1) {
5398 split = true; // second word is covered by full inits
5399 // Example: int a[] = { ... 42, foo() ... }
5400 }
5401
5402 // Here's a case where init0 is neither 0 nor -1:
5403 // byte a[] = { ... 0,0,foo(),0, 0,0,0,42 ... }
5404 // Assuming big-endian memory, init0, init1 are 0x0000FF00, 0x000000FF.
5405 // In this case the tile is not split; it is (jlong)42.
5406 // The big tile is stored down, and then the foo() value is inserted.
5407 // (If there were foo(),foo() instead of foo(),0, init0 would be -1.)
5408
5409 Node* ctl = old->in(MemNode::Control);
5410 Node* adr = make_raw_address(offset, phase);
5411 const TypePtr* atp = TypeRawPtr::BOTTOM;
5412
5413 // One or two coalesced stores to plop down.
5414 Node* st[2];
5415 intptr_t off[2];
5416 int nst = 0;
5417 if (!split) {
5418 ++new_long;
5419 off[nst] = offset;
5420 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5421 phase->longcon(con), T_LONG, MemNode::unordered);
5422 } else {
5423 // Omit either if it is a zero.
5424 if (con0 != 0) {
5425 ++new_int;
5426 off[nst] = offset;
5427 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5428 phase->intcon(con0), T_INT, MemNode::unordered);
5429 }
5430 if (con1 != 0) {
5431 ++new_int;
5432 offset += BytesPerInt;
5433 adr = make_raw_address(offset, phase);
5434 off[nst] = offset;
5435 st[nst++] = StoreNode::make(*phase, ctl, zmem, adr, atp,
5436 phase->intcon(con1), T_INT, MemNode::unordered);
5437 }
5438 }
5439
5440 // Insert second store first, then the first before the second.
5441 // Insert each one just before any overlapping non-constant stores.
5442 while (nst > 0) {
5443 Node* st1 = st[--nst];
5444 C->copy_node_notes_to(st1, old);
5445 st1 = phase->transform(st1);
5446 offset = off[nst];
5447 assert(offset >= header_size, "do not smash header");
5448 int ins_idx = captured_store_insertion_point(offset, /*size:*/0, phase);
5449 guarantee(ins_idx != 0, "must re-insert constant store");
5450 if (ins_idx < 0) ins_idx = -ins_idx; // never overlap
5451 if (ins_idx > InitializeNode::RawStores && in(ins_idx-1) == zmem)
5452 set_req(--ins_idx, st1);
5453 else
5454 ins_req(ins_idx, st1);
5455 }
5456 }
5457
5458 if (PrintCompilation && WizardMode)
5459 tty->print_cr("Changed %d/%d subword/long constants into %d/%d int/long",
5460 old_subword, old_long, new_int, new_long);
5461 if (C->log() != nullptr)
5462 C->log()->elem("comment that='%d/%d subword/long to %d/%d int/long'",
5463 old_subword, old_long, new_int, new_long);
5464
5465 // Clean up any remaining occurrences of zmem:
5466 remove_extra_zeroes();
5467 }
5468
5469 // Explore forward from in(start) to find the first fully initialized
5470 // word, and return its offset. Skip groups of subword stores which
5471 // together initialize full words. If in(start) is itself part of a
5472 // fully initialized word, return the offset of in(start). If there
5473 // are no following full-word stores, or if something is fishy, return
5474 // a negative value.
5475 intptr_t InitializeNode::find_next_fullword_store(uint start, PhaseGVN* phase) {
5476 int int_map = 0;
5477 intptr_t int_map_off = 0;
5478 const int FULL_MAP = right_n_bits(BytesPerInt); // the int_map we hope for
5479
5480 for (uint i = start, limit = req(); i < limit; i++) {
5481 Node* st = in(i);
5482
5483 intptr_t st_off = get_store_offset(st, phase);
5484 if (st_off < 0) break; // return conservative answer
5485
5486 int st_size = st->as_Store()->memory_size();
5487 if (st_size >= BytesPerInt && (st_off % BytesPerInt) == 0) {
5488 return st_off; // we found a complete word init
5489 }
5490
5491 // update the map:
5492
5493 intptr_t this_int_off = align_down(st_off, BytesPerInt);
5494 if (this_int_off != int_map_off) {
5495 // reset the map:
5496 int_map = 0;
5497 int_map_off = this_int_off;
5498 }
5499
5500 int subword_off = st_off - this_int_off;
5501 int_map |= right_n_bits(st_size) << subword_off;
5502 if ((int_map & FULL_MAP) == FULL_MAP) {
5503 return this_int_off; // we found a complete word init
5504 }
5505
5506 // Did this store hit or cross the word boundary?
5507 intptr_t next_int_off = align_down(st_off + st_size, BytesPerInt);
5508 if (next_int_off == this_int_off + BytesPerInt) {
5509 // We passed the current int, without fully initializing it.
5510 int_map_off = next_int_off;
5511 int_map >>= BytesPerInt;
5512 } else if (next_int_off > this_int_off + BytesPerInt) {
5513 // We passed the current and next int.
5514 return this_int_off + BytesPerInt;
5515 }
5516 }
5517
5518 return -1;
5519 }
5520
5521
5522 // Called when the associated AllocateNode is expanded into CFG.
5523 // At this point, we may perform additional optimizations.
5524 // Linearize the stores by ascending offset, to make memory
5525 // activity as coherent as possible.
5526 Node* InitializeNode::complete_stores(Node* rawctl, Node* rawmem, Node* rawptr,
5527 intptr_t header_size,
5528 Node* size_in_bytes,
5529 PhaseIterGVN* phase) {
5530 assert(!is_complete(), "not already complete");
5531 assert(stores_are_sane(phase), "");
5532 assert(allocation() != nullptr, "must be present");
5533
5534 remove_extra_zeroes();
5535
5536 if (ReduceFieldZeroing || ReduceBulkZeroing)
5537 // reduce instruction count for common initialization patterns
5538 coalesce_subword_stores(header_size, size_in_bytes, phase);
5539
5540 Node* zmem = zero_memory(); // initially zero memory state
5541 Node* inits = zmem; // accumulating a linearized chain of inits
5542 #ifdef ASSERT
5543 intptr_t first_offset = allocation()->minimum_header_size();
5544 intptr_t last_init_off = first_offset; // previous init offset
5545 intptr_t last_init_end = first_offset; // previous init offset+size
5546 intptr_t last_tile_end = first_offset; // previous tile offset+size
5547 #endif
5548 intptr_t zeroes_done = header_size;
5549
5550 bool do_zeroing = true; // we might give up if inits are very sparse
5551 int big_init_gaps = 0; // how many large gaps have we seen?
5552
5553 if (UseTLAB && ZeroTLAB) do_zeroing = false;
5554 if (!ReduceFieldZeroing && !ReduceBulkZeroing) do_zeroing = false;
5555
5556 for (uint i = InitializeNode::RawStores, limit = req(); i < limit; i++) {
5557 Node* st = in(i);
5558 intptr_t st_off = get_store_offset(st, phase);
5559 if (st_off < 0)
5560 break; // unknown junk in the inits
5561 if (st->in(MemNode::Memory) != zmem)
5562 break; // complicated store chains somehow in list
5563
5564 int st_size = st->as_Store()->memory_size();
5565 intptr_t next_init_off = st_off + st_size;
5566
5567 if (do_zeroing && zeroes_done < next_init_off) {
5568 // See if this store needs a zero before it or under it.
5569 intptr_t zeroes_needed = st_off;
5570
5571 if (st_size < BytesPerInt) {
5572 // Look for subword stores which only partially initialize words.
5573 // If we find some, we must lay down some word-level zeroes first,
5574 // underneath the subword stores.
5575 //
5576 // Examples:
5577 // byte[] a = { p,q,r,s } => a[0]=p,a[1]=q,a[2]=r,a[3]=s
5578 // byte[] a = { x,y,0,0 } => a[0..3] = 0, a[0]=x,a[1]=y
5579 // byte[] a = { 0,0,z,0 } => a[0..3] = 0, a[2]=z
5580 //
5581 // Note: coalesce_subword_stores may have already done this,
5582 // if it was prompted by constant non-zero subword initializers.
5583 // But this case can still arise with non-constant stores.
5584
5585 intptr_t next_full_store = find_next_fullword_store(i, phase);
5586
5587 // In the examples above:
5588 // in(i) p q r s x y z
5589 // st_off 12 13 14 15 12 13 14
5590 // st_size 1 1 1 1 1 1 1
5591 // next_full_s. 12 16 16 16 16 16 16
5592 // z's_done 12 16 16 16 12 16 12
5593 // z's_needed 12 16 16 16 16 16 16
5594 // zsize 0 0 0 0 4 0 4
5595 if (next_full_store < 0) {
5596 // Conservative tack: Zero to end of current word.
5597 zeroes_needed = align_up(zeroes_needed, BytesPerInt);
5598 } else {
5599 // Zero to beginning of next fully initialized word.
5600 // Or, don't zero at all, if we are already in that word.
5601 assert(next_full_store >= zeroes_needed, "must go forward");
5602 assert((next_full_store & (BytesPerInt-1)) == 0, "even boundary");
5603 zeroes_needed = next_full_store;
5604 }
5605 }
5606
5607 if (zeroes_needed > zeroes_done) {
5608 intptr_t zsize = zeroes_needed - zeroes_done;
5609 // Do some incremental zeroing on rawmem, in parallel with inits.
5610 zeroes_done = align_down(zeroes_done, BytesPerInt);
5611 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5612 allocation()->in(AllocateNode::InitValue),
5613 allocation()->in(AllocateNode::RawInitValue),
5614 zeroes_done, zeroes_needed,
5615 phase);
5616 zeroes_done = zeroes_needed;
5617 if (zsize > InitArrayShortSize && ++big_init_gaps > 2)
5618 do_zeroing = false; // leave the hole, next time
5619 }
5620 }
5621
5622 // Collect the store and move on:
5623 phase->replace_input_of(st, MemNode::Memory, inits);
5624 inits = st; // put it on the linearized chain
5625 set_req(i, zmem); // unhook from previous position
5626
5627 if (zeroes_done == st_off)
5628 zeroes_done = next_init_off;
5629
5630 assert(!do_zeroing || zeroes_done >= next_init_off, "don't miss any");
5631
5632 #ifdef ASSERT
5633 // Various order invariants. Weaker than stores_are_sane because
5634 // a large constant tile can be filled in by smaller non-constant stores.
5635 assert(st_off >= last_init_off, "inits do not reverse");
5636 last_init_off = st_off;
5637 const Type* val = nullptr;
5638 if (st_size >= BytesPerInt &&
5639 (val = phase->type(st->in(MemNode::ValueIn)))->singleton() &&
5640 (int)val->basic_type() < (int)T_OBJECT) {
5641 assert(st_off >= last_tile_end, "tiles do not overlap");
5642 assert(st_off >= last_init_end, "tiles do not overwrite inits");
5643 last_tile_end = MAX2(last_tile_end, next_init_off);
5644 } else {
5645 intptr_t st_tile_end = align_up(next_init_off, BytesPerLong);
5646 assert(st_tile_end >= last_tile_end, "inits stay with tiles");
5647 assert(st_off >= last_init_end, "inits do not overlap");
5648 last_init_end = next_init_off; // it's a non-tile
5649 }
5650 #endif //ASSERT
5651 }
5652
5653 remove_extra_zeroes(); // clear out all the zmems left over
5654 add_req(inits);
5655
5656 if (!(UseTLAB && ZeroTLAB)) {
5657 // If anything remains to be zeroed, zero it all now.
5658 zeroes_done = align_down(zeroes_done, BytesPerInt);
5659 // if it is the last unused 4 bytes of an instance, forget about it
5660 intptr_t size_limit = phase->find_intptr_t_con(size_in_bytes, max_jint);
5661 if (zeroes_done + BytesPerLong >= size_limit) {
5662 AllocateNode* alloc = allocation();
5663 assert(alloc != nullptr, "must be present");
5664 if (alloc != nullptr && alloc->Opcode() == Op_Allocate) {
5665 Node* klass_node = alloc->in(AllocateNode::KlassNode);
5666 ciKlass* k = phase->type(klass_node)->is_instklassptr()->instance_klass();
5667 if (zeroes_done == k->layout_helper())
5668 zeroes_done = size_limit;
5669 }
5670 }
5671 if (zeroes_done < size_limit) {
5672 rawmem = ClearArrayNode::clear_memory(rawctl, rawmem, rawptr,
5673 allocation()->in(AllocateNode::InitValue),
5674 allocation()->in(AllocateNode::RawInitValue),
5675 zeroes_done, size_in_bytes, phase);
5676 }
5677 }
5678
5679 set_complete(phase);
5680 return rawmem;
5681 }
5682
5683
5684 #ifdef ASSERT
5685 bool InitializeNode::stores_are_sane(PhaseValues* phase) {
5686 if (is_complete())
5687 return true; // stores could be anything at this point
5688 assert(allocation() != nullptr, "must be present");
5689 intptr_t last_off = allocation()->minimum_header_size();
5690 for (uint i = InitializeNode::RawStores; i < req(); i++) {
5691 Node* st = in(i);
5692 intptr_t st_off = get_store_offset(st, phase);
5693 if (st_off < 0) continue; // ignore dead garbage
5694 if (last_off > st_off) {
5695 tty->print_cr("*** bad store offset at %d: %zd > %zd", i, last_off, st_off);
5696 this->dump(2);
5697 assert(false, "ascending store offsets");
5698 return false;
5699 }
5700 last_off = st_off + st->as_Store()->memory_size();
5701 }
5702 return true;
5703 }
5704 #endif //ASSERT
5705
5706
5707
5708
5709 //============================MergeMemNode=====================================
5710 //
5711 // SEMANTICS OF MEMORY MERGES: A MergeMem is a memory state assembled from several
5712 // contributing store or call operations. Each contributor provides the memory
5713 // state for a particular "alias type" (see Compile::alias_type). For example,
5714 // if a MergeMem has an input X for alias category #6, then any memory reference
5715 // to alias category #6 may use X as its memory state input, as an exact equivalent
5716 // to using the MergeMem as a whole.
5717 // Load<6>( MergeMem(<6>: X, ...), p ) <==> Load<6>(X,p)
5718 //
5719 // (Here, the <N> notation gives the index of the relevant adr_type.)
5720 //
5721 // In one special case (and more cases in the future), alias categories overlap.
5722 // The special alias category "Bot" (Compile::AliasIdxBot) includes all memory
5723 // states. Therefore, if a MergeMem has only one contributing input W for Bot,
5724 // it is exactly equivalent to that state W:
5725 // MergeMem(<Bot>: W) <==> W
5726 //
5727 // Usually, the merge has more than one input. In that case, where inputs
5728 // overlap (i.e., one is Bot), the narrower alias type determines the memory
5729 // state for that type, and the wider alias type (Bot) fills in everywhere else:
5730 // Load<5>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<5>(W,p)
5731 // Load<6>( MergeMem(<Bot>: W, <6>: X), p ) <==> Load<6>(X,p)
5732 //
5733 // A merge can take a "wide" memory state as one of its narrow inputs.
5734 // This simply means that the merge observes out only the relevant parts of
5735 // the wide input. That is, wide memory states arriving at narrow merge inputs
5736 // are implicitly "filtered" or "sliced" as necessary. (This is rare.)
5737 //
5738 // These rules imply that MergeMem nodes may cascade (via their <Bot> links),
5739 // and that memory slices "leak through":
5740 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y)) <==> MergeMem(<Bot>: W, <7>: Y)
5741 //
5742 // But, in such a cascade, repeated memory slices can "block the leak":
5743 // MergeMem(<Bot>: MergeMem(<Bot>: W, <7>: Y), <7>: Y') <==> MergeMem(<Bot>: W, <7>: Y')
5744 //
5745 // In the last example, Y is not part of the combined memory state of the
5746 // outermost MergeMem. The system must, of course, prevent unschedulable
5747 // memory states from arising, so you can be sure that the state Y is somehow
5748 // a precursor to state Y'.
5749 //
5750 //
5751 // REPRESENTATION OF MEMORY MERGES: The indexes used to address the Node::in array
5752 // of each MergeMemNode array are exactly the numerical alias indexes, including
5753 // but not limited to AliasIdxTop, AliasIdxBot, and AliasIdxRaw. The functions
5754 // Compile::alias_type (and kin) produce and manage these indexes.
5755 //
5756 // By convention, the value of in(AliasIdxTop) (i.e., in(1)) is always the top node.
5757 // (Note that this provides quick access to the top node inside MergeMem methods,
5758 // without the need to reach out via TLS to Compile::current.)
5759 //
5760 // As a consequence of what was just described, a MergeMem that represents a full
5761 // memory state has an edge in(AliasIdxBot) which is a "wide" memory state,
5762 // containing all alias categories.
5763 //
5764 // MergeMem nodes never (?) have control inputs, so in(0) is null.
5765 //
5766 // All other edges in(N) (including in(AliasIdxRaw), which is in(3)) are either
5767 // a memory state for the alias type <N>, or else the top node, meaning that
5768 // there is no particular input for that alias type. Note that the length of
5769 // a MergeMem is variable, and may be extended at any time to accommodate new
5770 // memory states at larger alias indexes. When merges grow, they are of course
5771 // filled with "top" in the unused in() positions.
5772 //
5773 // This use of top is named "empty_memory()", or "empty_mem" (no-memory) as a variable.
5774 // (Top was chosen because it works smoothly with passes like GCM.)
5775 //
5776 // For convenience, we hardwire the alias index for TypeRawPtr::BOTTOM. (It is
5777 // the type of random VM bits like TLS references.) Since it is always the
5778 // first non-Bot memory slice, some low-level loops use it to initialize an
5779 // index variable: for (i = AliasIdxRaw; i < req(); i++).
5780 //
5781 //
5782 // ACCESSORS: There is a special accessor MergeMemNode::base_memory which returns
5783 // the distinguished "wide" state. The accessor MergeMemNode::memory_at(N) returns
5784 // the memory state for alias type <N>, or (if there is no particular slice at <N>,
5785 // it returns the base memory. To prevent bugs, memory_at does not accept <Top>
5786 // or <Bot> indexes. The iterator MergeMemStream provides robust iteration over
5787 // MergeMem nodes or pairs of such nodes, ensuring that the non-top edges are visited.
5788 //
5789 // %%%% We may get rid of base_memory as a separate accessor at some point; it isn't
5790 // really that different from the other memory inputs. An abbreviation called
5791 // "bot_memory()" for "memory_at(AliasIdxBot)" would keep code tidy.
5792 //
5793 //
5794 // PARTIAL MEMORY STATES: During optimization, MergeMem nodes may arise that represent
5795 // partial memory states. When a Phi splits through a MergeMem, the copy of the Phi
5796 // that "emerges though" the base memory will be marked as excluding the alias types
5797 // of the other (narrow-memory) copies which "emerged through" the narrow edges:
5798 //
5799 // Phi<Bot>(U, MergeMem(<Bot>: W, <8>: Y))
5800 // ==Ideal=> MergeMem(<Bot>: Phi<Bot-8>(U, W), Phi<8>(U, Y))
5801 //
5802 // This strange "subtraction" effect is necessary to ensure IGVN convergence.
5803 // (It is currently unimplemented.) As you can see, the resulting merge is
5804 // actually a disjoint union of memory states, rather than an overlay.
5805 //
5806
5807 //------------------------------MergeMemNode-----------------------------------
5808 Node* MergeMemNode::make_empty_memory() {
5809 Node* empty_memory = (Node*) Compile::current()->top();
5810 assert(empty_memory->is_top(), "correct sentinel identity");
5811 return empty_memory;
5812 }
5813
5814 MergeMemNode::MergeMemNode(Node *new_base) : Node(1+Compile::AliasIdxRaw) {
5815 init_class_id(Class_MergeMem);
5816 // all inputs are nullified in Node::Node(int)
5817 // set_input(0, nullptr); // no control input
5818
5819 // Initialize the edges uniformly to top, for starters.
5820 Node* empty_mem = make_empty_memory();
5821 for (uint i = Compile::AliasIdxTop; i < req(); i++) {
5822 init_req(i,empty_mem);
5823 }
5824 assert(empty_memory() == empty_mem, "");
5825
5826 if( new_base != nullptr && new_base->is_MergeMem() ) {
5827 MergeMemNode* mdef = new_base->as_MergeMem();
5828 assert(mdef->empty_memory() == empty_mem, "consistent sentinels");
5829 for (MergeMemStream mms(this, mdef); mms.next_non_empty2(); ) {
5830 mms.set_memory(mms.memory2());
5831 }
5832 assert(base_memory() == mdef->base_memory(), "");
5833 } else {
5834 set_base_memory(new_base);
5835 }
5836 }
5837
5838 // Make a new, untransformed MergeMem with the same base as 'mem'.
5839 // If mem is itself a MergeMem, populate the result with the same edges.
5840 MergeMemNode* MergeMemNode::make(Node* mem) {
5841 return new MergeMemNode(mem);
5842 }
5843
5844 //------------------------------cmp--------------------------------------------
5845 uint MergeMemNode::hash() const { return NO_HASH; }
5846 bool MergeMemNode::cmp( const Node &n ) const {
5847 return (&n == this); // Always fail except on self
5848 }
5849
5850 //------------------------------Identity---------------------------------------
5851 Node* MergeMemNode::Identity(PhaseGVN* phase) {
5852 // Identity if this merge point does not record any interesting memory
5853 // disambiguations.
5854 Node* base_mem = base_memory();
5855 Node* empty_mem = empty_memory();
5856 if (base_mem != empty_mem) { // Memory path is not dead?
5857 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5858 Node* mem = in(i);
5859 if (mem != empty_mem && mem != base_mem) {
5860 return this; // Many memory splits; no change
5861 }
5862 }
5863 }
5864 return base_mem; // No memory splits; ID on the one true input
5865 }
5866
5867 //------------------------------Ideal------------------------------------------
5868 // This method is invoked recursively on chains of MergeMem nodes
5869 Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
5870 // Remove chain'd MergeMems
5871 //
5872 // This is delicate, because the each "in(i)" (i >= Raw) is interpreted
5873 // relative to the "in(Bot)". Since we are patching both at the same time,
5874 // we have to be careful to read each "in(i)" relative to the old "in(Bot)",
5875 // but rewrite each "in(i)" relative to the new "in(Bot)".
5876 Node *progress = nullptr;
5877
5878
5879 Node* old_base = base_memory();
5880 Node* empty_mem = empty_memory();
5881 if (old_base == empty_mem)
5882 return nullptr; // Dead memory path.
5883
5884 MergeMemNode* old_mbase;
5885 if (old_base != nullptr && old_base->is_MergeMem())
5886 old_mbase = old_base->as_MergeMem();
5887 else
5888 old_mbase = nullptr;
5889 Node* new_base = old_base;
5890
5891 // simplify stacked MergeMems in base memory
5892 if (old_mbase) new_base = old_mbase->base_memory();
5893
5894 // the base memory might contribute new slices beyond my req()
5895 if (old_mbase) grow_to_match(old_mbase);
5896
5897 // Note: We do not call verify_sparse on entry, because inputs
5898 // can normalize to the base_memory via subsume_node or similar
5899 // mechanisms. This method repairs that damage.
5900
5901 assert(!old_mbase || old_mbase->is_empty_memory(empty_mem), "consistent sentinels");
5902
5903 // Look at each slice.
5904 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5905 Node* old_in = in(i);
5906 // calculate the old memory value
5907 Node* old_mem = old_in;
5908 if (old_mem == empty_mem) old_mem = old_base;
5909 assert(old_mem == memory_at(i), "");
5910
5911 // maybe update (reslice) the old memory value
5912
5913 // simplify stacked MergeMems
5914 Node* new_mem = old_mem;
5915 MergeMemNode* old_mmem;
5916 if (old_mem != nullptr && old_mem->is_MergeMem())
5917 old_mmem = old_mem->as_MergeMem();
5918 else
5919 old_mmem = nullptr;
5920 if (old_mmem == this) {
5921 // This can happen if loops break up and safepoints disappear.
5922 // A merge of BotPtr (default) with a RawPtr memory derived from a
5923 // safepoint can be rewritten to a merge of the same BotPtr with
5924 // the BotPtr phi coming into the loop. If that phi disappears
5925 // also, we can end up with a self-loop of the mergemem.
5926 // In general, if loops degenerate and memory effects disappear,
5927 // a mergemem can be left looking at itself. This simply means
5928 // that the mergemem's default should be used, since there is
5929 // no longer any apparent effect on this slice.
5930 // Note: If a memory slice is a MergeMem cycle, it is unreachable
5931 // from start. Update the input to TOP.
5932 new_mem = (new_base == this || new_base == empty_mem)? empty_mem : new_base;
5933 }
5934 else if (old_mmem != nullptr) {
5935 new_mem = old_mmem->memory_at(i);
5936 }
5937 // else preceding memory was not a MergeMem
5938
5939 // maybe store down a new value
5940 Node* new_in = new_mem;
5941 if (new_in == new_base) new_in = empty_mem;
5942
5943 if (new_in != old_in) {
5944 // Warning: Do not combine this "if" with the previous "if"
5945 // A memory slice might have be be rewritten even if it is semantically
5946 // unchanged, if the base_memory value has changed.
5947 set_req_X(i, new_in, phase);
5948 progress = this; // Report progress
5949 }
5950 }
5951
5952 if (new_base != old_base) {
5953 set_req_X(Compile::AliasIdxBot, new_base, phase);
5954 // Don't use set_base_memory(new_base), because we need to update du.
5955 assert(base_memory() == new_base, "");
5956 progress = this;
5957 }
5958
5959 if( base_memory() == this ) {
5960 // a self cycle indicates this memory path is dead
5961 set_req(Compile::AliasIdxBot, empty_mem);
5962 }
5963
5964 // Resolve external cycles by calling Ideal on a MergeMem base_memory
5965 // Recursion must occur after the self cycle check above
5966 if( base_memory()->is_MergeMem() ) {
5967 MergeMemNode *new_mbase = base_memory()->as_MergeMem();
5968 Node *m = phase->transform(new_mbase); // Rollup any cycles
5969 if( m != nullptr &&
5970 (m->is_top() ||
5971 (m->is_MergeMem() && m->as_MergeMem()->base_memory() == empty_mem)) ) {
5972 // propagate rollup of dead cycle to self
5973 set_req(Compile::AliasIdxBot, empty_mem);
5974 }
5975 }
5976
5977 if( base_memory() == empty_mem ) {
5978 progress = this;
5979 // Cut inputs during Parse phase only.
5980 // During Optimize phase a dead MergeMem node will be subsumed by Top.
5981 if( !can_reshape ) {
5982 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
5983 if( in(i) != empty_mem ) { set_req(i, empty_mem); }
5984 }
5985 }
5986 }
5987
5988 if( !progress && base_memory()->is_Phi() && can_reshape ) {
5989 // Check if PhiNode::Ideal's "Split phis through memory merges"
5990 // transform should be attempted. Look for this->phi->this cycle.
5991 uint merge_width = req();
5992 if (merge_width > Compile::AliasIdxRaw) {
5993 PhiNode* phi = base_memory()->as_Phi();
5994 for( uint i = 1; i < phi->req(); ++i ) {// For all paths in
5995 if (phi->in(i) == this) {
5996 phase->is_IterGVN()->_worklist.push(phi);
5997 break;
5998 }
5999 }
6000 }
6001 }
6002
6003 assert(progress || verify_sparse(), "please, no dups of base");
6004 return progress;
6005 }
6006
6007 //-------------------------set_base_memory-------------------------------------
6008 void MergeMemNode::set_base_memory(Node *new_base) {
6009 Node* empty_mem = empty_memory();
6010 set_req(Compile::AliasIdxBot, new_base);
6011 assert(memory_at(req()) == new_base, "must set default memory");
6012 // Clear out other occurrences of new_base:
6013 if (new_base != empty_mem) {
6014 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6015 if (in(i) == new_base) set_req(i, empty_mem);
6016 }
6017 }
6018 }
6019
6020 //------------------------------out_RegMask------------------------------------
6021 const RegMask &MergeMemNode::out_RegMask() const {
6022 return RegMask::Empty;
6023 }
6024
6025 //------------------------------dump_spec--------------------------------------
6026 #ifndef PRODUCT
6027 void MergeMemNode::dump_spec(outputStream *st) const {
6028 st->print(" {");
6029 Node* base_mem = base_memory();
6030 for( uint i = Compile::AliasIdxRaw; i < req(); i++ ) {
6031 Node* mem = (in(i) != nullptr) ? memory_at(i) : base_mem;
6032 if (mem == base_mem) { st->print(" -"); continue; }
6033 st->print( " N%d:", mem->_idx );
6034 Compile::current()->get_adr_type(i)->dump_on(st);
6035 }
6036 st->print(" }");
6037 }
6038 #endif // !PRODUCT
6039
6040
6041 #ifdef ASSERT
6042 static bool might_be_same(Node* a, Node* b) {
6043 if (a == b) return true;
6044 if (!(a->is_Phi() || b->is_Phi())) return false;
6045 // phis shift around during optimization
6046 return true; // pretty stupid...
6047 }
6048
6049 // verify a narrow slice (either incoming or outgoing)
6050 static void verify_memory_slice(const MergeMemNode* m, int alias_idx, Node* n) {
6051 if (!VerifyAliases) return; // don't bother to verify unless requested
6052 if (VMError::is_error_reported()) return; // muzzle asserts when debugging an error
6053 if (Node::in_dump()) return; // muzzle asserts when printing
6054 assert(alias_idx >= Compile::AliasIdxRaw, "must not disturb base_memory or sentinel");
6055 assert(n != nullptr, "");
6056 // Elide intervening MergeMem's
6057 while (n->is_MergeMem()) {
6058 n = n->as_MergeMem()->memory_at(alias_idx);
6059 }
6060 Compile* C = Compile::current();
6061 const TypePtr* n_adr_type = n->adr_type();
6062 if (n == m->empty_memory()) {
6063 // Implicit copy of base_memory()
6064 } else if (n_adr_type != TypePtr::BOTTOM) {
6065 assert(n_adr_type != nullptr, "new memory must have a well-defined adr_type");
6066 assert(C->must_alias(n_adr_type, alias_idx), "new memory must match selected slice");
6067 } else {
6068 // A few places like make_runtime_call "know" that VM calls are narrow,
6069 // and can be used to update only the VM bits stored as TypeRawPtr::BOTTOM.
6070 bool expected_wide_mem = false;
6071 if (n == m->base_memory()) {
6072 expected_wide_mem = true;
6073 } else if (alias_idx == Compile::AliasIdxRaw ||
6074 n == m->memory_at(Compile::AliasIdxRaw)) {
6075 expected_wide_mem = true;
6076 } else if (!C->alias_type(alias_idx)->is_rewritable()) {
6077 // memory can "leak through" calls on channels that
6078 // are write-once. Allow this also.
6079 expected_wide_mem = true;
6080 }
6081 assert(expected_wide_mem, "expected narrow slice replacement");
6082 }
6083 }
6084 #else // !ASSERT
6085 #define verify_memory_slice(m,i,n) (void)(0) // PRODUCT version is no-op
6086 #endif
6087
6088
6089 //-----------------------------memory_at---------------------------------------
6090 Node* MergeMemNode::memory_at(uint alias_idx) const {
6091 assert(alias_idx >= Compile::AliasIdxRaw ||
6092 (alias_idx == Compile::AliasIdxBot && !Compile::current()->do_aliasing()),
6093 "must avoid base_memory and AliasIdxTop");
6094
6095 // Otherwise, it is a narrow slice.
6096 Node* n = alias_idx < req() ? in(alias_idx) : empty_memory();
6097 if (is_empty_memory(n)) {
6098 // the array is sparse; empty slots are the "top" node
6099 n = base_memory();
6100 assert(Node::in_dump()
6101 || n == nullptr || n->bottom_type() == Type::TOP
6102 || n->adr_type() == nullptr // address is TOP
6103 || n->adr_type() == TypePtr::BOTTOM
6104 || n->adr_type() == TypeRawPtr::BOTTOM
6105 || !Compile::current()->do_aliasing(),
6106 "must be a wide memory");
6107 // do_aliasing == false if we are organizing the memory states manually.
6108 // See verify_memory_slice for comments on TypeRawPtr::BOTTOM.
6109 } else {
6110 // make sure the stored slice is sane
6111 #ifdef ASSERT
6112 if (VMError::is_error_reported() || Node::in_dump()) {
6113 } else if (might_be_same(n, base_memory())) {
6114 // Give it a pass: It is a mostly harmless repetition of the base.
6115 // This can arise normally from node subsumption during optimization.
6116 } else {
6117 verify_memory_slice(this, alias_idx, n);
6118 }
6119 #endif
6120 }
6121 return n;
6122 }
6123
6124 //---------------------------set_memory_at-------------------------------------
6125 void MergeMemNode::set_memory_at(uint alias_idx, Node *n) {
6126 verify_memory_slice(this, alias_idx, n);
6127 Node* empty_mem = empty_memory();
6128 if (n == base_memory()) n = empty_mem; // collapse default
6129 uint need_req = alias_idx+1;
6130 if (req() < need_req) {
6131 if (n == empty_mem) return; // already the default, so do not grow me
6132 // grow the sparse array
6133 do {
6134 add_req(empty_mem);
6135 } while (req() < need_req);
6136 }
6137 set_req( alias_idx, n );
6138 }
6139
6140
6141
6142 //--------------------------iteration_setup------------------------------------
6143 void MergeMemNode::iteration_setup(const MergeMemNode* other) {
6144 if (other != nullptr) {
6145 grow_to_match(other);
6146 // invariant: the finite support of mm2 is within mm->req()
6147 #ifdef ASSERT
6148 for (uint i = req(); i < other->req(); i++) {
6149 assert(other->is_empty_memory(other->in(i)), "slice left uncovered");
6150 }
6151 #endif
6152 }
6153 // Replace spurious copies of base_memory by top.
6154 Node* base_mem = base_memory();
6155 if (base_mem != nullptr && !base_mem->is_top()) {
6156 for (uint i = Compile::AliasIdxBot+1, imax = req(); i < imax; i++) {
6157 if (in(i) == base_mem)
6158 set_req(i, empty_memory());
6159 }
6160 }
6161 }
6162
6163 //---------------------------grow_to_match-------------------------------------
6164 void MergeMemNode::grow_to_match(const MergeMemNode* other) {
6165 Node* empty_mem = empty_memory();
6166 assert(other->is_empty_memory(empty_mem), "consistent sentinels");
6167 // look for the finite support of the other memory
6168 for (uint i = other->req(); --i >= req(); ) {
6169 if (other->in(i) != empty_mem) {
6170 uint new_len = i+1;
6171 while (req() < new_len) add_req(empty_mem);
6172 break;
6173 }
6174 }
6175 }
6176
6177 //---------------------------verify_sparse-------------------------------------
6178 #ifndef PRODUCT
6179 bool MergeMemNode::verify_sparse() const {
6180 assert(is_empty_memory(make_empty_memory()), "sane sentinel");
6181 Node* base_mem = base_memory();
6182 // The following can happen in degenerate cases, since empty==top.
6183 if (is_empty_memory(base_mem)) return true;
6184 for (uint i = Compile::AliasIdxRaw; i < req(); i++) {
6185 assert(in(i) != nullptr, "sane slice");
6186 if (in(i) == base_mem) return false; // should have been the sentinel value!
6187 }
6188 return true;
6189 }
6190
6191 bool MergeMemStream::match_memory(Node* mem, const MergeMemNode* mm, int idx) {
6192 Node* n;
6193 n = mm->in(idx);
6194 if (mem == n) return true; // might be empty_memory()
6195 n = (idx == Compile::AliasIdxBot)? mm->base_memory(): mm->memory_at(idx);
6196 if (mem == n) return true;
6197 return false;
6198 }
6199 #endif // !PRODUCT